1b2441318SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0 21da177e4SLinus Torvalds /* 31da177e4SLinus Torvalds * linux/fs/namei.c 41da177e4SLinus Torvalds * 51da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 61da177e4SLinus Torvalds */ 71da177e4SLinus Torvalds 81da177e4SLinus Torvalds /* 91da177e4SLinus Torvalds * Some corrections by tytso. 101da177e4SLinus Torvalds */ 111da177e4SLinus Torvalds 121da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 131da177e4SLinus Torvalds * lookup logic. 141da177e4SLinus Torvalds */ 151da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 161da177e4SLinus Torvalds */ 171da177e4SLinus Torvalds 181da177e4SLinus Torvalds #include <linux/init.h> 19630d9c47SPaul Gortmaker #include <linux/export.h> 2044696908SDavid S. Miller #include <linux/kernel.h> 211da177e4SLinus Torvalds #include <linux/slab.h> 221da177e4SLinus Torvalds #include <linux/fs.h> 231da177e4SLinus Torvalds #include <linux/namei.h> 241da177e4SLinus Torvalds #include <linux/pagemap.h> 250eeca283SRobert Love #include <linux/fsnotify.h> 261da177e4SLinus Torvalds #include <linux/personality.h> 271da177e4SLinus Torvalds #include <linux/security.h> 286146f0d5SMimi Zohar #include <linux/ima.h> 291da177e4SLinus Torvalds #include <linux/syscalls.h> 301da177e4SLinus Torvalds #include <linux/mount.h> 311da177e4SLinus Torvalds #include <linux/audit.h> 3216f7e0feSRandy Dunlap #include <linux/capability.h> 33834f2a4aSTrond Myklebust #include <linux/file.h> 345590ff0dSUlrich Drepper #include <linux/fcntl.h> 3508ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 365ad4e53bSAl Viro #include <linux/fs_struct.h> 37e77819e5SLinus Torvalds #include <linux/posix_acl.h> 3899d263d4SLinus Torvalds #include <linux/hash.h> 392a18da7aSGeorge Spelvin #include <linux/bitops.h> 40aeaa4a79SEric W. Biederman #include <linux/init_task.h> 417c0f6ba6SLinus Torvalds #include <linux/uaccess.h> 421da177e4SLinus Torvalds 43e81e3f4dSEric Paris #include "internal.h" 44c7105365SAl Viro #include "mount.h" 45e81e3f4dSEric Paris 461da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 471da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 481da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 491da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 501da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 511da177e4SLinus Torvalds * 521da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 531da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 541da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 551da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 561da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 571da177e4SLinus Torvalds * the special cases of the former code. 581da177e4SLinus Torvalds * 591da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 601da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 611da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 621da177e4SLinus Torvalds * 631da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 641da177e4SLinus Torvalds * resolution to correspond with current state of the code. 651da177e4SLinus Torvalds * 661da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 671da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 681da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 691da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 701da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 711da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 721da177e4SLinus Torvalds */ 731da177e4SLinus Torvalds 741da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 751da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 761da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 771da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 781da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 791da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 8025985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 811da177e4SLinus Torvalds * 821da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 831da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 841da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 851da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 861da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 871da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 881da177e4SLinus Torvalds * and in the old Linux semantics. 891da177e4SLinus Torvalds */ 901da177e4SLinus Torvalds 911da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 921da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 931da177e4SLinus Torvalds * 941da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 951da177e4SLinus Torvalds */ 961da177e4SLinus Torvalds 971da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 981da177e4SLinus Torvalds * inside the path - always follow. 991da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 1001da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 1011da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 1021da177e4SLinus Torvalds * otherwise - don't follow. 1031da177e4SLinus Torvalds * (applied in that order). 1041da177e4SLinus Torvalds * 1051da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1061da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1071da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1081da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1091da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1101da177e4SLinus Torvalds */ 1111da177e4SLinus Torvalds /* 1121da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 113a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1141da177e4SLinus Torvalds * any extra contention... 1151da177e4SLinus Torvalds */ 1161da177e4SLinus Torvalds 1171da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1181da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1191da177e4SLinus Torvalds * kernel data space before using them.. 1201da177e4SLinus Torvalds * 1211da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1221da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1231da177e4SLinus Torvalds */ 1247950e385SJeff Layton 125fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12691a27b2aSJeff Layton 12751f39a1fSDavid Drysdale struct filename * 12891a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12991a27b2aSJeff Layton { 13094b5d262SAl Viro struct filename *result; 1317950e385SJeff Layton char *kname; 13294b5d262SAl Viro int len; 1331da177e4SLinus Torvalds 1347ac86265SJeff Layton result = audit_reusename(filename); 1357ac86265SJeff Layton if (result) 1367ac86265SJeff Layton return result; 1377ac86265SJeff Layton 1387950e385SJeff Layton result = __getname(); 1393f9f0aa6SLinus Torvalds if (unlikely(!result)) 1404043cde8SEric Paris return ERR_PTR(-ENOMEM); 1411da177e4SLinus Torvalds 1427950e385SJeff Layton /* 1437950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1447950e385SJeff Layton * allocation 1457950e385SJeff Layton */ 146fd2f7cb5SAl Viro kname = (char *)result->iname; 14791a27b2aSJeff Layton result->name = kname; 1487950e385SJeff Layton 14994b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 15091a27b2aSJeff Layton if (unlikely(len < 0)) { 15194b5d262SAl Viro __putname(result); 15294b5d262SAl Viro return ERR_PTR(len); 15391a27b2aSJeff Layton } 1543f9f0aa6SLinus Torvalds 1557950e385SJeff Layton /* 1567950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1577950e385SJeff Layton * separate struct filename so we can dedicate the entire 1587950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1597950e385SJeff Layton * userland. 1607950e385SJeff Layton */ 16194b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 162fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1637950e385SJeff Layton kname = (char *)result; 1647950e385SJeff Layton 165fd2f7cb5SAl Viro /* 166fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 167fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 168fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 169fd2f7cb5SAl Viro */ 170fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 17194b5d262SAl Viro if (unlikely(!result)) { 17294b5d262SAl Viro __putname(kname); 17394b5d262SAl Viro return ERR_PTR(-ENOMEM); 1747950e385SJeff Layton } 1757950e385SJeff Layton result->name = kname; 17694b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17794b5d262SAl Viro if (unlikely(len < 0)) { 17894b5d262SAl Viro __putname(kname); 17994b5d262SAl Viro kfree(result); 18094b5d262SAl Viro return ERR_PTR(len); 18194b5d262SAl Viro } 18294b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18394b5d262SAl Viro __putname(kname); 18494b5d262SAl Viro kfree(result); 18594b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18694b5d262SAl Viro } 1877950e385SJeff Layton } 1887950e385SJeff Layton 18994b5d262SAl Viro result->refcnt = 1; 1903f9f0aa6SLinus Torvalds /* The empty path is special. */ 1913f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1923f9f0aa6SLinus Torvalds if (empty) 1931fa1e7f6SAndy Whitcroft *empty = 1; 19494b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19594b5d262SAl Viro putname(result); 19694b5d262SAl Viro return ERR_PTR(-ENOENT); 1971da177e4SLinus Torvalds } 19894b5d262SAl Viro } 1997950e385SJeff Layton 2007950e385SJeff Layton result->uptr = filename; 201c4ad8f98SLinus Torvalds result->aname = NULL; 2021da177e4SLinus Torvalds audit_getname(result); 2031da177e4SLinus Torvalds return result; 2043f9f0aa6SLinus Torvalds } 2053f9f0aa6SLinus Torvalds 20691a27b2aSJeff Layton struct filename * 20791a27b2aSJeff Layton getname(const char __user * filename) 208f52e0c11SAl Viro { 209f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 210f52e0c11SAl Viro } 211f52e0c11SAl Viro 212c4ad8f98SLinus Torvalds struct filename * 213c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 214c4ad8f98SLinus Torvalds { 215c4ad8f98SLinus Torvalds struct filename *result; 21608518549SPaul Moore int len = strlen(filename) + 1; 217c4ad8f98SLinus Torvalds 218c4ad8f98SLinus Torvalds result = __getname(); 219c4ad8f98SLinus Torvalds if (unlikely(!result)) 220c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 221c4ad8f98SLinus Torvalds 22208518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 223fd2f7cb5SAl Viro result->name = (char *)result->iname; 22408518549SPaul Moore } else if (len <= PATH_MAX) { 22530ce4d19SAl Viro const size_t size = offsetof(struct filename, iname[1]); 22608518549SPaul Moore struct filename *tmp; 22708518549SPaul Moore 22830ce4d19SAl Viro tmp = kmalloc(size, GFP_KERNEL); 22908518549SPaul Moore if (unlikely(!tmp)) { 23008518549SPaul Moore __putname(result); 23108518549SPaul Moore return ERR_PTR(-ENOMEM); 23208518549SPaul Moore } 23308518549SPaul Moore tmp->name = (char *)result; 23408518549SPaul Moore result = tmp; 23508518549SPaul Moore } else { 23608518549SPaul Moore __putname(result); 23708518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23808518549SPaul Moore } 23908518549SPaul Moore memcpy((char *)result->name, filename, len); 240c4ad8f98SLinus Torvalds result->uptr = NULL; 241c4ad8f98SLinus Torvalds result->aname = NULL; 24255422d0bSPaul Moore result->refcnt = 1; 243fd3522fdSPaul Moore audit_getname(result); 244c4ad8f98SLinus Torvalds 245c4ad8f98SLinus Torvalds return result; 246c4ad8f98SLinus Torvalds } 247c4ad8f98SLinus Torvalds 24891a27b2aSJeff Layton void putname(struct filename *name) 2491da177e4SLinus Torvalds { 25055422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 25155422d0bSPaul Moore 25255422d0bSPaul Moore if (--name->refcnt > 0) 25355422d0bSPaul Moore return; 25455422d0bSPaul Moore 255fd2f7cb5SAl Viro if (name->name != name->iname) { 25655422d0bSPaul Moore __putname(name->name); 25755422d0bSPaul Moore kfree(name); 25855422d0bSPaul Moore } else 25955422d0bSPaul Moore __putname(name); 2601da177e4SLinus Torvalds } 2611da177e4SLinus Torvalds 262e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 263e77819e5SLinus Torvalds { 26484635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 265e77819e5SLinus Torvalds struct posix_acl *acl; 266e77819e5SLinus Torvalds 267e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2683567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2693567866bSAl Viro if (!acl) 270e77819e5SLinus Torvalds return -EAGAIN; 2713567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 272b8a7a3a6SAndreas Gruenbacher if (is_uncached_acl(acl)) 273e77819e5SLinus Torvalds return -ECHILD; 274206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 275e77819e5SLinus Torvalds } 276e77819e5SLinus Torvalds 2772982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2784e34e719SChristoph Hellwig if (IS_ERR(acl)) 2794e34e719SChristoph Hellwig return PTR_ERR(acl); 280e77819e5SLinus Torvalds if (acl) { 281e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 282e77819e5SLinus Torvalds posix_acl_release(acl); 283e77819e5SLinus Torvalds return error; 284e77819e5SLinus Torvalds } 28584635d68SLinus Torvalds #endif 286e77819e5SLinus Torvalds 287e77819e5SLinus Torvalds return -EAGAIN; 288e77819e5SLinus Torvalds } 289e77819e5SLinus Torvalds 2905909ccaaSLinus Torvalds /* 291948409c7SAndreas Gruenbacher * This does the basic permission checking 2925909ccaaSLinus Torvalds */ 2937e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2945909ccaaSLinus Torvalds { 29526cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2965909ccaaSLinus Torvalds 2978e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2985909ccaaSLinus Torvalds mode >>= 6; 2995909ccaaSLinus Torvalds else { 300e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 3017e40145eSAl Viro int error = check_acl(inode, mask); 3025909ccaaSLinus Torvalds if (error != -EAGAIN) 3035909ccaaSLinus Torvalds return error; 3045909ccaaSLinus Torvalds } 3055909ccaaSLinus Torvalds 3065909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3075909ccaaSLinus Torvalds mode >>= 3; 3085909ccaaSLinus Torvalds } 3095909ccaaSLinus Torvalds 3105909ccaaSLinus Torvalds /* 3115909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3125909ccaaSLinus Torvalds */ 3139c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3145909ccaaSLinus Torvalds return 0; 3155909ccaaSLinus Torvalds return -EACCES; 3165909ccaaSLinus Torvalds } 3171da177e4SLinus Torvalds 3181da177e4SLinus Torvalds /** 3191da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3201da177e4SLinus Torvalds * @inode: inode to check access rights for 3218fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3221da177e4SLinus Torvalds * 3231da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3241da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3251da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 326b74c79e9SNick Piggin * are used for other things. 327b74c79e9SNick Piggin * 328b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 329b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 330b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3311da177e4SLinus Torvalds */ 3322830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3331da177e4SLinus Torvalds { 3345909ccaaSLinus Torvalds int ret; 3351da177e4SLinus Torvalds 3361da177e4SLinus Torvalds /* 337948409c7SAndreas Gruenbacher * Do the basic permission checks. 3381da177e4SLinus Torvalds */ 3397e40145eSAl Viro ret = acl_permission_check(inode, mask); 3405909ccaaSLinus Torvalds if (ret != -EACCES) 3415909ccaaSLinus Torvalds return ret; 3421da177e4SLinus Torvalds 343d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 344d594e7ecSAl Viro /* DACs are overridable for directories */ 345d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34623adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34723adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 348d594e7ecSAl Viro return 0; 34923adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3501da177e4SLinus Torvalds return 0; 3512a4c2242SStephen Smalley return -EACCES; 3522a4c2242SStephen Smalley } 3531da177e4SLinus Torvalds 3541da177e4SLinus Torvalds /* 3551da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3561da177e4SLinus Torvalds */ 3577ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 358d594e7ecSAl Viro if (mask == MAY_READ) 35923adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3601da177e4SLinus Torvalds return 0; 3612a4c2242SStephen Smalley /* 3622a4c2242SStephen Smalley * Read/write DACs are always overridable. 3632a4c2242SStephen Smalley * Executable DACs are overridable when there is 3642a4c2242SStephen Smalley * at least one exec bit set. 3652a4c2242SStephen Smalley */ 3662a4c2242SStephen Smalley if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 3672a4c2242SStephen Smalley if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3682a4c2242SStephen Smalley return 0; 3691da177e4SLinus Torvalds 3701da177e4SLinus Torvalds return -EACCES; 3711da177e4SLinus Torvalds } 3724d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3731da177e4SLinus Torvalds 3743ddcd056SLinus Torvalds /* 3753ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3763ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3773ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3783ddcd056SLinus Torvalds * permission function, use the fast case". 3793ddcd056SLinus Torvalds */ 3803ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3813ddcd056SLinus Torvalds { 3823ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3833ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3843ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3853ddcd056SLinus Torvalds 3863ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3873ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3883ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3893ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3903ddcd056SLinus Torvalds } 3913ddcd056SLinus Torvalds return generic_permission(inode, mask); 3923ddcd056SLinus Torvalds } 3933ddcd056SLinus Torvalds 394cb23beb5SChristoph Hellwig /** 3950bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 3960bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 39755852635SRandy Dunlap * @inode: Inode to check permission on 3980bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 3990bdaea90SDavid Howells * 4000bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4010bdaea90SDavid Howells */ 4020bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4030bdaea90SDavid Howells { 4040bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4050bdaea90SDavid Howells umode_t mode = inode->i_mode; 4060bdaea90SDavid Howells 4070bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 408bc98a42cSDavid Howells if (sb_rdonly(sb) && (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4090bdaea90SDavid Howells return -EROFS; 4100bdaea90SDavid Howells } 4110bdaea90SDavid Howells return 0; 4120bdaea90SDavid Howells } 4130bdaea90SDavid Howells 4140bdaea90SDavid Howells /** 4150bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4160bdaea90SDavid Howells * @inode: Inode to check permission on 4170bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4180bdaea90SDavid Howells * 4190bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4200bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4210bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4220bdaea90SDavid Howells * 4230bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4240bdaea90SDavid Howells */ 4250bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4260bdaea90SDavid Howells { 4270bdaea90SDavid Howells int retval; 4280bdaea90SDavid Howells 4290bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4300bdaea90SDavid Howells if (retval) 4310bdaea90SDavid Howells return retval; 4324bfd054aSEric Biggers 4334bfd054aSEric Biggers if (unlikely(mask & MAY_WRITE)) { 4344bfd054aSEric Biggers /* 4354bfd054aSEric Biggers * Nobody gets write access to an immutable file. 4364bfd054aSEric Biggers */ 4374bfd054aSEric Biggers if (IS_IMMUTABLE(inode)) 4384bfd054aSEric Biggers return -EPERM; 4394bfd054aSEric Biggers 4404bfd054aSEric Biggers /* 4414bfd054aSEric Biggers * Updating mtime will likely cause i_uid and i_gid to be 4424bfd054aSEric Biggers * written back improperly if their true value is unknown 4434bfd054aSEric Biggers * to the vfs. 4444bfd054aSEric Biggers */ 4454bfd054aSEric Biggers if (HAS_UNMAPPED_ID(inode)) 4464bfd054aSEric Biggers return -EACCES; 4474bfd054aSEric Biggers } 4484bfd054aSEric Biggers 4494bfd054aSEric Biggers retval = do_inode_permission(inode, mask); 4504bfd054aSEric Biggers if (retval) 4514bfd054aSEric Biggers return retval; 4524bfd054aSEric Biggers 4534bfd054aSEric Biggers retval = devcgroup_inode_permission(inode, mask); 4544bfd054aSEric Biggers if (retval) 4554bfd054aSEric Biggers return retval; 4564bfd054aSEric Biggers 4574bfd054aSEric Biggers return security_inode_permission(inode, mask); 4580bdaea90SDavid Howells } 4594d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4600bdaea90SDavid Howells 4610bdaea90SDavid Howells /** 4625dd784d0SJan Blunck * path_get - get a reference to a path 4635dd784d0SJan Blunck * @path: path to get the reference to 4645dd784d0SJan Blunck * 4655dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4665dd784d0SJan Blunck */ 467dcf787f3SAl Viro void path_get(const struct path *path) 4685dd784d0SJan Blunck { 4695dd784d0SJan Blunck mntget(path->mnt); 4705dd784d0SJan Blunck dget(path->dentry); 4715dd784d0SJan Blunck } 4725dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4735dd784d0SJan Blunck 4745dd784d0SJan Blunck /** 4751d957f9bSJan Blunck * path_put - put a reference to a path 4761d957f9bSJan Blunck * @path: path to put the reference to 4771d957f9bSJan Blunck * 4781d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4791d957f9bSJan Blunck */ 480dcf787f3SAl Viro void path_put(const struct path *path) 4811da177e4SLinus Torvalds { 4821d957f9bSJan Blunck dput(path->dentry); 4831d957f9bSJan Blunck mntput(path->mnt); 4841da177e4SLinus Torvalds } 4851d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4861da177e4SLinus Torvalds 487894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 4881f55a6ecSAl Viro struct nameidata { 4891f55a6ecSAl Viro struct path path; 4901f55a6ecSAl Viro struct qstr last; 4911f55a6ecSAl Viro struct path root; 4921f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 4931f55a6ecSAl Viro unsigned int flags; 494ab87f9a5SAleksa Sarai unsigned seq, m_seq, r_seq; 4951f55a6ecSAl Viro int last_type; 4961f55a6ecSAl Viro unsigned depth; 497756daf26SNeilBrown int total_link_count; 498697fc6caSAl Viro struct saved { 499697fc6caSAl Viro struct path link; 500fceef393SAl Viro struct delayed_call done; 501697fc6caSAl Viro const char *name; 5020450b2d1SAl Viro unsigned seq; 503894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5049883d185SAl Viro struct filename *name; 5059883d185SAl Viro struct nameidata *saved; 5069883d185SAl Viro unsigned root_seq; 5079883d185SAl Viro int dfd; 5083859a271SKees Cook } __randomize_layout; 5091f55a6ecSAl Viro 5109883d185SAl Viro static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) 511894bc8c4SAl Viro { 512756daf26SNeilBrown struct nameidata *old = current->nameidata; 513756daf26SNeilBrown p->stack = p->internal; 514c8a53ee5SAl Viro p->dfd = dfd; 515c8a53ee5SAl Viro p->name = name; 516756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 5179883d185SAl Viro p->saved = old; 518756daf26SNeilBrown current->nameidata = p; 519894bc8c4SAl Viro } 520894bc8c4SAl Viro 5219883d185SAl Viro static void restore_nameidata(void) 522894bc8c4SAl Viro { 5239883d185SAl Viro struct nameidata *now = current->nameidata, *old = now->saved; 524756daf26SNeilBrown 525756daf26SNeilBrown current->nameidata = old; 526756daf26SNeilBrown if (old) 527756daf26SNeilBrown old->total_link_count = now->total_link_count; 528e1a63bbcSAl Viro if (now->stack != now->internal) 529756daf26SNeilBrown kfree(now->stack); 530894bc8c4SAl Viro } 531894bc8c4SAl Viro 532894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 533894bc8c4SAl Viro { 534bc40aee0SAl Viro struct saved *p; 535bc40aee0SAl Viro 536bc40aee0SAl Viro if (nd->flags & LOOKUP_RCU) { 5376da2ec56SKees Cook p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved), 538bc40aee0SAl Viro GFP_ATOMIC); 539bc40aee0SAl Viro if (unlikely(!p)) 540bc40aee0SAl Viro return -ECHILD; 541bc40aee0SAl Viro } else { 5426da2ec56SKees Cook p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved), 543894bc8c4SAl Viro GFP_KERNEL); 544894bc8c4SAl Viro if (unlikely(!p)) 545894bc8c4SAl Viro return -ENOMEM; 546bc40aee0SAl Viro } 547894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 548894bc8c4SAl Viro nd->stack = p; 549894bc8c4SAl Viro return 0; 550894bc8c4SAl Viro } 551894bc8c4SAl Viro 552397d425dSEric W. Biederman /** 5536b03f7edSAl Viro * path_connected - Verify that a dentry is below mnt.mnt_root 554397d425dSEric W. Biederman * 555397d425dSEric W. Biederman * Rename can sometimes move a file or directory outside of a bind 556397d425dSEric W. Biederman * mount, path_connected allows those cases to be detected. 557397d425dSEric W. Biederman */ 5586b03f7edSAl Viro static bool path_connected(struct vfsmount *mnt, struct dentry *dentry) 559397d425dSEric W. Biederman { 56095dd7758SEric W. Biederman struct super_block *sb = mnt->mnt_sb; 561397d425dSEric W. Biederman 56295dd7758SEric W. Biederman /* Bind mounts and multi-root filesystems can have disconnected paths */ 56395dd7758SEric W. Biederman if (!(sb->s_iflags & SB_I_MULTIROOT) && (mnt->mnt_root == sb->s_root)) 564397d425dSEric W. Biederman return true; 565397d425dSEric W. Biederman 5666b03f7edSAl Viro return is_subdir(dentry, mnt->mnt_root); 567397d425dSEric W. Biederman } 568397d425dSEric W. Biederman 569894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 570894bc8c4SAl Viro { 571da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 572894bc8c4SAl Viro return 0; 573894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 574894bc8c4SAl Viro return 0; 575894bc8c4SAl Viro return __nd_alloc_stack(nd); 576894bc8c4SAl Viro } 577894bc8c4SAl Viro 5787973387aSAl Viro static void drop_links(struct nameidata *nd) 5797973387aSAl Viro { 5807973387aSAl Viro int i = nd->depth; 5817973387aSAl Viro while (i--) { 5827973387aSAl Viro struct saved *last = nd->stack + i; 583fceef393SAl Viro do_delayed_call(&last->done); 584fceef393SAl Viro clear_delayed_call(&last->done); 5857973387aSAl Viro } 5867973387aSAl Viro } 5877973387aSAl Viro 5887973387aSAl Viro static void terminate_walk(struct nameidata *nd) 5897973387aSAl Viro { 5907973387aSAl Viro drop_links(nd); 5917973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 5927973387aSAl Viro int i; 5937973387aSAl Viro path_put(&nd->path); 5947973387aSAl Viro for (i = 0; i < nd->depth; i++) 5957973387aSAl Viro path_put(&nd->stack[i].link); 59684a2bd39SAl Viro if (nd->flags & LOOKUP_ROOT_GRABBED) { 597102b8af2SAl Viro path_put(&nd->root); 59884a2bd39SAl Viro nd->flags &= ~LOOKUP_ROOT_GRABBED; 599102b8af2SAl Viro } 6007973387aSAl Viro } else { 6017973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 6027973387aSAl Viro rcu_read_unlock(); 6037973387aSAl Viro } 6047973387aSAl Viro nd->depth = 0; 6057973387aSAl Viro } 6067973387aSAl Viro 6077973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 6082aa38470SAl Viro static bool __legitimize_path(struct path *path, unsigned seq, unsigned mseq) 6097973387aSAl Viro { 6102aa38470SAl Viro int res = __legitimize_mnt(path->mnt, mseq); 6117973387aSAl Viro if (unlikely(res)) { 6127973387aSAl Viro if (res > 0) 6137973387aSAl Viro path->mnt = NULL; 6147973387aSAl Viro path->dentry = NULL; 6157973387aSAl Viro return false; 6167973387aSAl Viro } 6177973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 6187973387aSAl Viro path->dentry = NULL; 6197973387aSAl Viro return false; 6207973387aSAl Viro } 6217973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6227973387aSAl Viro } 6237973387aSAl Viro 6242aa38470SAl Viro static inline bool legitimize_path(struct nameidata *nd, 6252aa38470SAl Viro struct path *path, unsigned seq) 6262aa38470SAl Viro { 6272aa38470SAl Viro return __legitimize_path(path, nd->m_seq, seq); 6282aa38470SAl Viro } 6292aa38470SAl Viro 6307973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6317973387aSAl Viro { 6327973387aSAl Viro int i; 6337973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6347973387aSAl Viro struct saved *last = nd->stack + i; 6357973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6367973387aSAl Viro drop_links(nd); 6377973387aSAl Viro nd->depth = i + 1; 6387973387aSAl Viro return false; 6397973387aSAl Viro } 6407973387aSAl Viro } 6417973387aSAl Viro return true; 6427973387aSAl Viro } 6437973387aSAl Viro 644ee594bffSAl Viro static bool legitimize_root(struct nameidata *nd) 645ee594bffSAl Viro { 646adb21d2bSAleksa Sarai /* 647adb21d2bSAleksa Sarai * For scoped-lookups (where nd->root has been zeroed), we need to 648adb21d2bSAleksa Sarai * restart the whole lookup from scratch -- because set_root() is wrong 649adb21d2bSAleksa Sarai * for these lookups (nd->dfd is the root, not the filesystem root). 650adb21d2bSAleksa Sarai */ 651adb21d2bSAleksa Sarai if (!nd->root.mnt && (nd->flags & LOOKUP_IS_SCOPED)) 652adb21d2bSAleksa Sarai return false; 653adb21d2bSAleksa Sarai /* Nothing to do if nd->root is zero or is managed by the VFS user. */ 654ee594bffSAl Viro if (!nd->root.mnt || (nd->flags & LOOKUP_ROOT)) 655ee594bffSAl Viro return true; 65684a2bd39SAl Viro nd->flags |= LOOKUP_ROOT_GRABBED; 657ee594bffSAl Viro return legitimize_path(nd, &nd->root, nd->root_seq); 658ee594bffSAl Viro } 659ee594bffSAl Viro 66019660af7SAl Viro /* 66131e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 66219660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 66319660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 66457e3715cSMike Marshall * normal reference counts on dentries and vfsmounts to transition to ref-walk 66519660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 66619660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 66719660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 66819660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 66931e6b01fSNick Piggin */ 67031e6b01fSNick Piggin 67131e6b01fSNick Piggin /** 67219660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 67319660af7SAl Viro * @nd: nameidata pathwalk data 67439191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 67531e6b01fSNick Piggin * 6764675ac39SAl Viro * unlazy_walk attempts to legitimize the current nd->path and nd->root 6774675ac39SAl Viro * for ref-walk mode. 6784675ac39SAl Viro * Must be called from rcu-walk context. 6797973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6807973387aSAl Viro * terminate_walk(). 68131e6b01fSNick Piggin */ 6824675ac39SAl Viro static int unlazy_walk(struct nameidata *nd) 68331e6b01fSNick Piggin { 68431e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 68531e6b01fSNick Piggin 68631e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 687e5c832d5SLinus Torvalds 688e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6897973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6904675ac39SAl Viro goto out1; 69184a2bd39SAl Viro if (unlikely(!legitimize_path(nd, &nd->path, nd->seq))) 69284a2bd39SAl Viro goto out; 693ee594bffSAl Viro if (unlikely(!legitimize_root(nd))) 6944675ac39SAl Viro goto out; 6954675ac39SAl Viro rcu_read_unlock(); 6964675ac39SAl Viro BUG_ON(nd->inode != parent->d_inode); 6974675ac39SAl Viro return 0; 6984675ac39SAl Viro 69984a2bd39SAl Viro out1: 7004675ac39SAl Viro nd->path.mnt = NULL; 7014675ac39SAl Viro nd->path.dentry = NULL; 7024675ac39SAl Viro out: 7034675ac39SAl Viro rcu_read_unlock(); 7044675ac39SAl Viro return -ECHILD; 7054675ac39SAl Viro } 7064675ac39SAl Viro 7074675ac39SAl Viro /** 7084675ac39SAl Viro * unlazy_child - try to switch to ref-walk mode. 7094675ac39SAl Viro * @nd: nameidata pathwalk data 7104675ac39SAl Viro * @dentry: child of nd->path.dentry 7114675ac39SAl Viro * @seq: seq number to check dentry against 7124675ac39SAl Viro * Returns: 0 on success, -ECHILD on failure 7134675ac39SAl Viro * 7144675ac39SAl Viro * unlazy_child attempts to legitimize the current nd->path, nd->root and dentry 7154675ac39SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 7164675ac39SAl Viro * @nd. Must be called from rcu-walk context. 7174675ac39SAl Viro * Nothing should touch nameidata between unlazy_child() failure and 7184675ac39SAl Viro * terminate_walk(). 7194675ac39SAl Viro */ 7204675ac39SAl Viro static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned seq) 7214675ac39SAl Viro { 7224675ac39SAl Viro BUG_ON(!(nd->flags & LOOKUP_RCU)); 7234675ac39SAl Viro 7244675ac39SAl Viro nd->flags &= ~LOOKUP_RCU; 7254675ac39SAl Viro if (unlikely(!legitimize_links(nd))) 7264675ac39SAl Viro goto out2; 7277973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 7287973387aSAl Viro goto out2; 7294675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&nd->path.dentry->d_lockref))) 7307973387aSAl Viro goto out1; 73148a066e7SAl Viro 73215570086SLinus Torvalds /* 7334675ac39SAl Viro * We need to move both the parent and the dentry from the RCU domain 7344675ac39SAl Viro * to be properly refcounted. And the sequence number in the dentry 7354675ac39SAl Viro * validates *both* dentry counters, since we checked the sequence 7364675ac39SAl Viro * number of the parent after we got the child sequence number. So we 7374675ac39SAl Viro * know the parent must still be valid if the child sequence number is 73815570086SLinus Torvalds */ 7394675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) 740e5c832d5SLinus Torvalds goto out; 74184a2bd39SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 74284a2bd39SAl Viro goto out_dput; 743e5c832d5SLinus Torvalds /* 744e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 745e5c832d5SLinus Torvalds * still valid and get it if required. 746e5c832d5SLinus Torvalds */ 74784a2bd39SAl Viro if (unlikely(!legitimize_root(nd))) 74884a2bd39SAl Viro goto out_dput; 7498b61e74fSAl Viro rcu_read_unlock(); 75031e6b01fSNick Piggin return 0; 75119660af7SAl Viro 7527973387aSAl Viro out2: 7537973387aSAl Viro nd->path.mnt = NULL; 7547973387aSAl Viro out1: 7557973387aSAl Viro nd->path.dentry = NULL; 756e5c832d5SLinus Torvalds out: 7578b61e74fSAl Viro rcu_read_unlock(); 75884a2bd39SAl Viro return -ECHILD; 75984a2bd39SAl Viro out_dput: 76084a2bd39SAl Viro rcu_read_unlock(); 76184a2bd39SAl Viro dput(dentry); 76231e6b01fSNick Piggin return -ECHILD; 76331e6b01fSNick Piggin } 76431e6b01fSNick Piggin 7654ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 76634286d66SNick Piggin { 767a89f8337SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 7684ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 769a89f8337SAl Viro else 770a89f8337SAl Viro return 1; 77134286d66SNick Piggin } 77234286d66SNick Piggin 7739f1fafeeSAl Viro /** 7749f1fafeeSAl Viro * complete_walk - successful completion of path walk 7759f1fafeeSAl Viro * @nd: pointer nameidata 77639159de2SJeff Layton * 7779f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7789f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7799f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7809f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7819f1fafeeSAl Viro * need to drop nd->path. 78239159de2SJeff Layton */ 7839f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 78439159de2SJeff Layton { 78516c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 78639159de2SJeff Layton int status; 78739159de2SJeff Layton 7889f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 789adb21d2bSAleksa Sarai /* 790adb21d2bSAleksa Sarai * We don't want to zero nd->root for scoped-lookups or 791adb21d2bSAleksa Sarai * externally-managed nd->root. 792adb21d2bSAleksa Sarai */ 793adb21d2bSAleksa Sarai if (!(nd->flags & (LOOKUP_ROOT | LOOKUP_IS_SCOPED))) 7949f1fafeeSAl Viro nd->root.mnt = NULL; 7954675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 79648a066e7SAl Viro return -ECHILD; 79748a066e7SAl Viro } 7989f1fafeeSAl Viro 799adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) { 800adb21d2bSAleksa Sarai /* 801adb21d2bSAleksa Sarai * While the guarantee of LOOKUP_IS_SCOPED is (roughly) "don't 802adb21d2bSAleksa Sarai * ever step outside the root during lookup" and should already 803adb21d2bSAleksa Sarai * be guaranteed by the rest of namei, we want to avoid a namei 804adb21d2bSAleksa Sarai * BUG resulting in userspace being given a path that was not 805adb21d2bSAleksa Sarai * scoped within the root at some point during the lookup. 806adb21d2bSAleksa Sarai * 807adb21d2bSAleksa Sarai * So, do a final sanity-check to make sure that in the 808adb21d2bSAleksa Sarai * worst-case scenario (a complete bypass of LOOKUP_IS_SCOPED) 809adb21d2bSAleksa Sarai * we won't silently return an fd completely outside of the 810adb21d2bSAleksa Sarai * requested root to userspace. 811adb21d2bSAleksa Sarai * 812adb21d2bSAleksa Sarai * Userspace could move the path outside the root after this 813adb21d2bSAleksa Sarai * check, but as discussed elsewhere this is not a concern (the 814adb21d2bSAleksa Sarai * resolved file was inside the root at some point). 815adb21d2bSAleksa Sarai */ 816adb21d2bSAleksa Sarai if (!path_is_under(&nd->path, &nd->root)) 817adb21d2bSAleksa Sarai return -EXDEV; 818adb21d2bSAleksa Sarai } 819adb21d2bSAleksa Sarai 82016c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 82139159de2SJeff Layton return 0; 82239159de2SJeff Layton 823ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 82416c2cd71SAl Viro return 0; 82516c2cd71SAl Viro 826ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 82739159de2SJeff Layton if (status > 0) 82839159de2SJeff Layton return 0; 82939159de2SJeff Layton 83016c2cd71SAl Viro if (!status) 83139159de2SJeff Layton status = -ESTALE; 83216c2cd71SAl Viro 83339159de2SJeff Layton return status; 83439159de2SJeff Layton } 83539159de2SJeff Layton 836740a1678SAleksa Sarai static int set_root(struct nameidata *nd) 8372a737871SAl Viro { 83831e6b01fSNick Piggin struct fs_struct *fs = current->fs; 8399e6697e2SAl Viro 840adb21d2bSAleksa Sarai /* 841adb21d2bSAleksa Sarai * Jumping to the real root in a scoped-lookup is a BUG in namei, but we 842adb21d2bSAleksa Sarai * still have to ensure it doesn't happen because it will cause a breakout 843adb21d2bSAleksa Sarai * from the dirfd. 844adb21d2bSAleksa Sarai */ 845adb21d2bSAleksa Sarai if (WARN_ON(nd->flags & LOOKUP_IS_SCOPED)) 846adb21d2bSAleksa Sarai return -ENOTRECOVERABLE; 847adb21d2bSAleksa Sarai 8489e6697e2SAl Viro if (nd->flags & LOOKUP_RCU) { 8498f47a016SAl Viro unsigned seq; 850c28cc364SNick Piggin 851c28cc364SNick Piggin do { 852c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 85331e6b01fSNick Piggin nd->root = fs->root; 8548f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 855c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 8569e6697e2SAl Viro } else { 8579e6697e2SAl Viro get_fs_root(fs, &nd->root); 85884a2bd39SAl Viro nd->flags |= LOOKUP_ROOT_GRABBED; 8599e6697e2SAl Viro } 860740a1678SAleksa Sarai return 0; 86131e6b01fSNick Piggin } 86231e6b01fSNick Piggin 8637b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8647b9337aaSNick Piggin struct nameidata *nd) 865051d3812SIan Kent { 86631e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8674ac91378SJan Blunck dput(nd->path.dentry); 86831e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8694ac91378SJan Blunck mntput(nd->path.mnt); 8709a229683SHuang Shijie } 87131e6b01fSNick Piggin nd->path.mnt = path->mnt; 8724ac91378SJan Blunck nd->path.dentry = path->dentry; 873051d3812SIan Kent } 874051d3812SIan Kent 875248fb5b9SAl Viro static int nd_jump_root(struct nameidata *nd) 876248fb5b9SAl Viro { 877adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_BENEATH)) 878adb21d2bSAleksa Sarai return -EXDEV; 87972ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) { 88072ba2929SAleksa Sarai /* Absolute path arguments to path_init() are allowed. */ 88172ba2929SAleksa Sarai if (nd->path.mnt != NULL && nd->path.mnt != nd->root.mnt) 88272ba2929SAleksa Sarai return -EXDEV; 88372ba2929SAleksa Sarai } 884740a1678SAleksa Sarai if (!nd->root.mnt) { 885740a1678SAleksa Sarai int error = set_root(nd); 886740a1678SAleksa Sarai if (error) 887740a1678SAleksa Sarai return error; 888740a1678SAleksa Sarai } 889248fb5b9SAl Viro if (nd->flags & LOOKUP_RCU) { 890248fb5b9SAl Viro struct dentry *d; 891248fb5b9SAl Viro nd->path = nd->root; 892248fb5b9SAl Viro d = nd->path.dentry; 893248fb5b9SAl Viro nd->inode = d->d_inode; 894248fb5b9SAl Viro nd->seq = nd->root_seq; 895248fb5b9SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 896248fb5b9SAl Viro return -ECHILD; 897248fb5b9SAl Viro } else { 898248fb5b9SAl Viro path_put(&nd->path); 899248fb5b9SAl Viro nd->path = nd->root; 900248fb5b9SAl Viro path_get(&nd->path); 901248fb5b9SAl Viro nd->inode = nd->path.dentry->d_inode; 902248fb5b9SAl Viro } 903248fb5b9SAl Viro nd->flags |= LOOKUP_JUMPED; 904248fb5b9SAl Viro return 0; 905248fb5b9SAl Viro } 906248fb5b9SAl Viro 907b5fb63c1SChristoph Hellwig /* 9086b255391SAl Viro * Helper to directly jump to a known parsed path from ->get_link, 909b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 910b5fb63c1SChristoph Hellwig */ 9111bc82070SAleksa Sarai int nd_jump_link(struct path *path) 912b5fb63c1SChristoph Hellwig { 9134b99d499SAleksa Sarai int error = -ELOOP; 9146e77137bSAl Viro struct nameidata *nd = current->nameidata; 915b5fb63c1SChristoph Hellwig 9164b99d499SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_MAGICLINKS)) 9174b99d499SAleksa Sarai goto err; 9184b99d499SAleksa Sarai 91972ba2929SAleksa Sarai error = -EXDEV; 92072ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) { 92172ba2929SAleksa Sarai if (nd->path.mnt != path->mnt) 92272ba2929SAleksa Sarai goto err; 92372ba2929SAleksa Sarai } 924adb21d2bSAleksa Sarai /* Not currently safe for scoped-lookups. */ 925adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) 926adb21d2bSAleksa Sarai goto err; 92772ba2929SAleksa Sarai 9284b99d499SAleksa Sarai path_put(&nd->path); 929b5fb63c1SChristoph Hellwig nd->path = *path; 930b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 931b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 9321bc82070SAleksa Sarai return 0; 9334b99d499SAleksa Sarai 9344b99d499SAleksa Sarai err: 9354b99d499SAleksa Sarai path_put(path); 9364b99d499SAleksa Sarai return error; 937b5fb63c1SChristoph Hellwig } 938b5fb63c1SChristoph Hellwig 939b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 940574197e0SAl Viro { 94121c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 942fceef393SAl Viro do_delayed_call(&last->done); 9436548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 944b9ff4429SAl Viro path_put(&last->link); 945574197e0SAl Viro } 946574197e0SAl Viro 947561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 948561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 94930aba665SSalvatore Mesoraca int sysctl_protected_fifos __read_mostly; 95030aba665SSalvatore Mesoraca int sysctl_protected_regular __read_mostly; 951800179c9SKees Cook 952800179c9SKees Cook /** 953800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 95455852635SRandy Dunlap * @nd: nameidata pathwalk data 955800179c9SKees Cook * 956800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 957800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 958800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 959800179c9SKees Cook * processes from failing races against path names that may change out 960800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 961800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 962800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 963800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 964800179c9SKees Cook * 965800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 966800179c9SKees Cook */ 967ad6cc4c3SAl Viro static inline int may_follow_link(struct nameidata *nd, const struct inode *inode) 968800179c9SKees Cook { 969800179c9SKees Cook const struct inode *parent; 9702d7f9e2aSSeth Forshee kuid_t puid; 971800179c9SKees Cook 972800179c9SKees Cook if (!sysctl_protected_symlinks) 973800179c9SKees Cook return 0; 974800179c9SKees Cook 975800179c9SKees Cook /* Allowed if owner and follower match. */ 97681abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 977800179c9SKees Cook return 0; 978800179c9SKees Cook 979800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 980aa65fa35SAl Viro parent = nd->inode; 981800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 982800179c9SKees Cook return 0; 983800179c9SKees Cook 984800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 9852d7f9e2aSSeth Forshee puid = parent->i_uid; 9862d7f9e2aSSeth Forshee if (uid_valid(puid) && uid_eq(puid, inode->i_uid)) 987800179c9SKees Cook return 0; 988800179c9SKees Cook 98931956502SAl Viro if (nd->flags & LOOKUP_RCU) 99031956502SAl Viro return -ECHILD; 99131956502SAl Viro 992ea841bafSRichard Guy Briggs audit_inode(nd->name, nd->stack[0].link.dentry, 0); 993245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "follow_link"); 994800179c9SKees Cook return -EACCES; 995800179c9SKees Cook } 996800179c9SKees Cook 997800179c9SKees Cook /** 998800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 999800179c9SKees Cook * @inode: the source inode to hardlink from 1000800179c9SKees Cook * 1001800179c9SKees Cook * Return false if at least one of the following conditions: 1002800179c9SKees Cook * - inode is not a regular file 1003800179c9SKees Cook * - inode is setuid 1004800179c9SKees Cook * - inode is setgid and group-exec 1005800179c9SKees Cook * - access failure for read and write 1006800179c9SKees Cook * 1007800179c9SKees Cook * Otherwise returns true. 1008800179c9SKees Cook */ 1009800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 1010800179c9SKees Cook { 1011800179c9SKees Cook umode_t mode = inode->i_mode; 1012800179c9SKees Cook 1013800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 1014800179c9SKees Cook if (!S_ISREG(mode)) 1015800179c9SKees Cook return false; 1016800179c9SKees Cook 1017800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 1018800179c9SKees Cook if (mode & S_ISUID) 1019800179c9SKees Cook return false; 1020800179c9SKees Cook 1021800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 1022800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 1023800179c9SKees Cook return false; 1024800179c9SKees Cook 1025800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 1026800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 1027800179c9SKees Cook return false; 1028800179c9SKees Cook 1029800179c9SKees Cook return true; 1030800179c9SKees Cook } 1031800179c9SKees Cook 1032800179c9SKees Cook /** 1033800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 1034800179c9SKees Cook * @link: the source to hardlink from 1035800179c9SKees Cook * 1036800179c9SKees Cook * Block hardlink when all of: 1037800179c9SKees Cook * - sysctl_protected_hardlinks enabled 1038800179c9SKees Cook * - fsuid does not match inode 1039800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 1040f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 1041800179c9SKees Cook * 1042800179c9SKees Cook * Returns 0 if successful, -ve on error. 1043800179c9SKees Cook */ 1044800179c9SKees Cook static int may_linkat(struct path *link) 1045800179c9SKees Cook { 1046593d1ce8SEric W. Biederman struct inode *inode = link->dentry->d_inode; 1047593d1ce8SEric W. Biederman 1048593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 1049593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 1050593d1ce8SEric W. Biederman return -EOVERFLOW; 1051800179c9SKees Cook 1052800179c9SKees Cook if (!sysctl_protected_hardlinks) 1053800179c9SKees Cook return 0; 1054800179c9SKees Cook 1055800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 1056800179c9SKees Cook * otherwise, it must be a safe source. 1057800179c9SKees Cook */ 1058cc658db4SKees Cook if (safe_hardlink_source(inode) || inode_owner_or_capable(inode)) 1059800179c9SKees Cook return 0; 1060800179c9SKees Cook 1061245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "linkat"); 1062800179c9SKees Cook return -EPERM; 1063800179c9SKees Cook } 1064800179c9SKees Cook 106530aba665SSalvatore Mesoraca /** 106630aba665SSalvatore Mesoraca * may_create_in_sticky - Check whether an O_CREAT open in a sticky directory 106730aba665SSalvatore Mesoraca * should be allowed, or not, on files that already 106830aba665SSalvatore Mesoraca * exist. 1069d0cb5018SAl Viro * @dir_mode: mode bits of directory 1070d0cb5018SAl Viro * @dir_uid: owner of directory 107130aba665SSalvatore Mesoraca * @inode: the inode of the file to open 107230aba665SSalvatore Mesoraca * 107330aba665SSalvatore Mesoraca * Block an O_CREAT open of a FIFO (or a regular file) when: 107430aba665SSalvatore Mesoraca * - sysctl_protected_fifos (or sysctl_protected_regular) is enabled 107530aba665SSalvatore Mesoraca * - the file already exists 107630aba665SSalvatore Mesoraca * - we are in a sticky directory 107730aba665SSalvatore Mesoraca * - we don't own the file 107830aba665SSalvatore Mesoraca * - the owner of the directory doesn't own the file 107930aba665SSalvatore Mesoraca * - the directory is world writable 108030aba665SSalvatore Mesoraca * If the sysctl_protected_fifos (or sysctl_protected_regular) is set to 2 108130aba665SSalvatore Mesoraca * the directory doesn't have to be world writable: being group writable will 108230aba665SSalvatore Mesoraca * be enough. 108330aba665SSalvatore Mesoraca * 108430aba665SSalvatore Mesoraca * Returns 0 if the open is allowed, -ve on error. 108530aba665SSalvatore Mesoraca */ 1086d0cb5018SAl Viro static int may_create_in_sticky(umode_t dir_mode, kuid_t dir_uid, 108730aba665SSalvatore Mesoraca struct inode * const inode) 108830aba665SSalvatore Mesoraca { 108930aba665SSalvatore Mesoraca if ((!sysctl_protected_fifos && S_ISFIFO(inode->i_mode)) || 109030aba665SSalvatore Mesoraca (!sysctl_protected_regular && S_ISREG(inode->i_mode)) || 1091d0cb5018SAl Viro likely(!(dir_mode & S_ISVTX)) || 1092d0cb5018SAl Viro uid_eq(inode->i_uid, dir_uid) || 109330aba665SSalvatore Mesoraca uid_eq(current_fsuid(), inode->i_uid)) 109430aba665SSalvatore Mesoraca return 0; 109530aba665SSalvatore Mesoraca 1096d0cb5018SAl Viro if (likely(dir_mode & 0002) || 1097d0cb5018SAl Viro (dir_mode & 0020 && 109830aba665SSalvatore Mesoraca ((sysctl_protected_fifos >= 2 && S_ISFIFO(inode->i_mode)) || 109930aba665SSalvatore Mesoraca (sysctl_protected_regular >= 2 && S_ISREG(inode->i_mode))))) { 1100245d7369SKees Cook const char *operation = S_ISFIFO(inode->i_mode) ? 1101245d7369SKees Cook "sticky_create_fifo" : 1102245d7369SKees Cook "sticky_create_regular"; 1103245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_CREAT, operation); 110430aba665SSalvatore Mesoraca return -EACCES; 110530aba665SSalvatore Mesoraca } 110630aba665SSalvatore Mesoraca return 0; 110730aba665SSalvatore Mesoraca } 110830aba665SSalvatore Mesoraca 1109f015f126SDavid Howells /* 1110f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1111f015f126SDavid Howells * 1112f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1113f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1114f015f126SDavid Howells * Up is towards /. 1115f015f126SDavid Howells * 1116f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1117f015f126SDavid Howells * root. 1118f015f126SDavid Howells */ 1119bab77ebfSAl Viro int follow_up(struct path *path) 11201da177e4SLinus Torvalds { 11210714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 11220714a533SAl Viro struct mount *parent; 11231da177e4SLinus Torvalds struct dentry *mountpoint; 112499b7db7bSNick Piggin 112548a066e7SAl Viro read_seqlock_excl(&mount_lock); 11260714a533SAl Viro parent = mnt->mnt_parent; 11273c0a6163SAl Viro if (parent == mnt) { 112848a066e7SAl Viro read_sequnlock_excl(&mount_lock); 11291da177e4SLinus Torvalds return 0; 11301da177e4SLinus Torvalds } 11310714a533SAl Viro mntget(&parent->mnt); 1132a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 113348a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1134bab77ebfSAl Viro dput(path->dentry); 1135bab77ebfSAl Viro path->dentry = mountpoint; 1136bab77ebfSAl Viro mntput(path->mnt); 11370714a533SAl Viro path->mnt = &parent->mnt; 11381da177e4SLinus Torvalds return 1; 11391da177e4SLinus Torvalds } 11404d359507SAl Viro EXPORT_SYMBOL(follow_up); 11411da177e4SLinus Torvalds 11427ef482faSAl Viro static bool choose_mountpoint_rcu(struct mount *m, const struct path *root, 11437ef482faSAl Viro struct path *path, unsigned *seqp) 11447ef482faSAl Viro { 11457ef482faSAl Viro while (mnt_has_parent(m)) { 11467ef482faSAl Viro struct dentry *mountpoint = m->mnt_mountpoint; 11477ef482faSAl Viro 11487ef482faSAl Viro m = m->mnt_parent; 11497ef482faSAl Viro if (unlikely(root->dentry == mountpoint && 11507ef482faSAl Viro root->mnt == &m->mnt)) 11517ef482faSAl Viro break; 11527ef482faSAl Viro if (mountpoint != m->mnt.mnt_root) { 11537ef482faSAl Viro path->mnt = &m->mnt; 11547ef482faSAl Viro path->dentry = mountpoint; 11557ef482faSAl Viro *seqp = read_seqcount_begin(&mountpoint->d_seq); 11567ef482faSAl Viro return true; 11577ef482faSAl Viro } 11587ef482faSAl Viro } 11597ef482faSAl Viro return false; 11607ef482faSAl Viro } 11617ef482faSAl Viro 11622aa38470SAl Viro static bool choose_mountpoint(struct mount *m, const struct path *root, 11632aa38470SAl Viro struct path *path) 11642aa38470SAl Viro { 11652aa38470SAl Viro bool found; 11662aa38470SAl Viro 11672aa38470SAl Viro rcu_read_lock(); 11682aa38470SAl Viro while (1) { 11692aa38470SAl Viro unsigned seq, mseq = read_seqbegin(&mount_lock); 11702aa38470SAl Viro 11712aa38470SAl Viro found = choose_mountpoint_rcu(m, root, path, &seq); 11722aa38470SAl Viro if (unlikely(!found)) { 11732aa38470SAl Viro if (!read_seqretry(&mount_lock, mseq)) 11742aa38470SAl Viro break; 11752aa38470SAl Viro } else { 11762aa38470SAl Viro if (likely(__legitimize_path(path, seq, mseq))) 11772aa38470SAl Viro break; 11782aa38470SAl Viro rcu_read_unlock(); 11792aa38470SAl Viro path_put(path); 11802aa38470SAl Viro rcu_read_lock(); 11812aa38470SAl Viro } 11822aa38470SAl Viro } 11832aa38470SAl Viro rcu_read_unlock(); 11842aa38470SAl Viro return found; 11852aa38470SAl Viro } 11862aa38470SAl Viro 1187b5c84bf6SNick Piggin /* 11889875cf80SDavid Howells * Perform an automount 11899875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 11909875cf80SDavid Howells * were called with. 11911da177e4SLinus Torvalds */ 11921c9f5e06SAl Viro static int follow_automount(struct path *path, int *count, unsigned lookup_flags) 119331e6b01fSNick Piggin { 119425e195aaSAl Viro struct dentry *dentry = path->dentry; 11959875cf80SDavid Howells 11960ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 11970ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 11980ec26fd0SMiklos Szeredi * the name. 11990ec26fd0SMiklos Szeredi * 12000ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 12015a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 12020ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 12030ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 12040ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 12050ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 12065a30d8a2SDavid Howells */ 12071c9f5e06SAl Viro if (!(lookup_flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 12085d38f049SIan Kent LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 120925e195aaSAl Viro dentry->d_inode) 12109875cf80SDavid Howells return -EISDIR; 12110ec26fd0SMiklos Szeredi 12121c9f5e06SAl Viro if (count && (*count)++ >= MAXSYMLINKS) 12139875cf80SDavid Howells return -ELOOP; 12149875cf80SDavid Howells 121525e195aaSAl Viro return finish_automount(dentry->d_op->d_automount(path), path); 1216ea5b778aSDavid Howells } 12179875cf80SDavid Howells 12189875cf80SDavid Howells /* 12199deed3ebSAl Viro * mount traversal - out-of-line part. One note on ->d_flags accesses - 12209deed3ebSAl Viro * dentries are pinned but not locked here, so negative dentry can go 12219deed3ebSAl Viro * positive right under us. Use of smp_load_acquire() provides a barrier 12229deed3ebSAl Viro * sufficient for ->d_inode and ->d_flags consistency. 12239875cf80SDavid Howells */ 12249deed3ebSAl Viro static int __traverse_mounts(struct path *path, unsigned flags, bool *jumped, 12259deed3ebSAl Viro int *count, unsigned lookup_flags) 12269875cf80SDavid Howells { 12279deed3ebSAl Viro struct vfsmount *mnt = path->mnt; 12289875cf80SDavid Howells bool need_mntput = false; 12298aef1884SAl Viro int ret = 0; 12309875cf80SDavid Howells 12319deed3ebSAl Viro while (flags & DCACHE_MANAGED_DENTRY) { 1232cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1233cc53ce53SDavid Howells * being held. */ 1234d41efb52SAl Viro if (flags & DCACHE_MANAGE_TRANSIT) { 1235fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1236508c8772SAl Viro flags = smp_load_acquire(&path->dentry->d_flags); 1237cc53ce53SDavid Howells if (ret < 0) 12388aef1884SAl Viro break; 1239cc53ce53SDavid Howells } 1240cc53ce53SDavid Howells 12419deed3ebSAl Viro if (flags & DCACHE_MOUNTED) { // something's mounted on it.. 12429875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12439deed3ebSAl Viro if (mounted) { // ... in our namespace 12449875cf80SDavid Howells dput(path->dentry); 12459875cf80SDavid Howells if (need_mntput) 1246463ffb2eSAl Viro mntput(path->mnt); 1247463ffb2eSAl Viro path->mnt = mounted; 1248463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 12499deed3ebSAl Viro // here we know it's positive 12509deed3ebSAl Viro flags = path->dentry->d_flags; 12519875cf80SDavid Howells need_mntput = true; 12529875cf80SDavid Howells continue; 1253463ffb2eSAl Viro } 12541da177e4SLinus Torvalds } 12559875cf80SDavid Howells 12569deed3ebSAl Viro if (!(flags & DCACHE_NEED_AUTOMOUNT)) 12579deed3ebSAl Viro break; 12589deed3ebSAl Viro 12599deed3ebSAl Viro // uncovered automount point 12609deed3ebSAl Viro ret = follow_automount(path, count, lookup_flags); 12619deed3ebSAl Viro flags = smp_load_acquire(&path->dentry->d_flags); 12629875cf80SDavid Howells if (ret < 0) 12638aef1884SAl Viro break; 12649875cf80SDavid Howells } 12659875cf80SDavid Howells 12669deed3ebSAl Viro if (ret == -EISDIR) 12679deed3ebSAl Viro ret = 0; 12689deed3ebSAl Viro // possible if you race with several mount --move 12699deed3ebSAl Viro if (need_mntput && path->mnt == mnt) 12708aef1884SAl Viro mntput(path->mnt); 12719deed3ebSAl Viro if (!ret && unlikely(d_flags_negative(flags))) 1272d41efb52SAl Viro ret = -ENOENT; 12739deed3ebSAl Viro *jumped = need_mntput; 12748402752eSAl Viro return ret; 12751da177e4SLinus Torvalds } 12761da177e4SLinus Torvalds 12779deed3ebSAl Viro static inline int traverse_mounts(struct path *path, bool *jumped, 12789deed3ebSAl Viro int *count, unsigned lookup_flags) 12799deed3ebSAl Viro { 12809deed3ebSAl Viro unsigned flags = smp_load_acquire(&path->dentry->d_flags); 12819deed3ebSAl Viro 12829deed3ebSAl Viro /* fastpath */ 12839deed3ebSAl Viro if (likely(!(flags & DCACHE_MANAGED_DENTRY))) { 12849deed3ebSAl Viro *jumped = false; 12859deed3ebSAl Viro if (unlikely(d_flags_negative(flags))) 12869deed3ebSAl Viro return -ENOENT; 12879deed3ebSAl Viro return 0; 12889deed3ebSAl Viro } 12899deed3ebSAl Viro return __traverse_mounts(path, flags, jumped, count, lookup_flags); 12909deed3ebSAl Viro } 12919deed3ebSAl Viro 1292cc53ce53SDavid Howells int follow_down_one(struct path *path) 12931da177e4SLinus Torvalds { 12941da177e4SLinus Torvalds struct vfsmount *mounted; 12951da177e4SLinus Torvalds 12961c755af4SAl Viro mounted = lookup_mnt(path); 12971da177e4SLinus Torvalds if (mounted) { 12989393bd07SAl Viro dput(path->dentry); 12999393bd07SAl Viro mntput(path->mnt); 13009393bd07SAl Viro path->mnt = mounted; 13019393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 13021da177e4SLinus Torvalds return 1; 13031da177e4SLinus Torvalds } 13041da177e4SLinus Torvalds return 0; 13051da177e4SLinus Torvalds } 13064d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 13071da177e4SLinus Torvalds 13089875cf80SDavid Howells /* 13099deed3ebSAl Viro * Follow down to the covering mount currently visible to userspace. At each 13109deed3ebSAl Viro * point, the filesystem owning that dentry may be queried as to whether the 13119deed3ebSAl Viro * caller is permitted to proceed or not. 13129deed3ebSAl Viro */ 13139deed3ebSAl Viro int follow_down(struct path *path) 13149deed3ebSAl Viro { 13159deed3ebSAl Viro struct vfsmount *mnt = path->mnt; 13169deed3ebSAl Viro bool jumped; 13179deed3ebSAl Viro int ret = traverse_mounts(path, &jumped, NULL, 0); 13189deed3ebSAl Viro 13199deed3ebSAl Viro if (path->mnt != mnt) 13209deed3ebSAl Viro mntput(mnt); 13219deed3ebSAl Viro return ret; 13229deed3ebSAl Viro } 13239deed3ebSAl Viro EXPORT_SYMBOL(follow_down); 13249deed3ebSAl Viro 13259deed3ebSAl Viro /* 1326287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1327287548e4SAl Viro * we meet a managed dentry that would need blocking. 13289875cf80SDavid Howells */ 13299875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1330254cf582SAl Viro struct inode **inode, unsigned *seqp) 13319875cf80SDavid Howells { 1332ea936aebSAl Viro struct dentry *dentry = path->dentry; 1333ea936aebSAl Viro unsigned int flags = dentry->d_flags; 1334ea936aebSAl Viro 1335ea936aebSAl Viro if (likely(!(flags & DCACHE_MANAGED_DENTRY))) 1336ea936aebSAl Viro return true; 1337ea936aebSAl Viro 1338ea936aebSAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 1339ea936aebSAl Viro return false; 1340ea936aebSAl Viro 134162a7375eSIan Kent for (;;) { 134262a7375eSIan Kent /* 134362a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 134462a7375eSIan Kent * that wants to block transit. 134562a7375eSIan Kent */ 1346ea936aebSAl Viro if (unlikely(flags & DCACHE_MANAGE_TRANSIT)) { 1347ea936aebSAl Viro int res = dentry->d_op->d_manage(path, true); 1348ea936aebSAl Viro if (res) 1349ea936aebSAl Viro return res == -EISDIR; 1350ea936aebSAl Viro flags = dentry->d_flags; 1351b8faf035SNeilBrown } 135262a7375eSIan Kent 1353ea936aebSAl Viro if (flags & DCACHE_MOUNTED) { 1354ea936aebSAl Viro struct mount *mounted = __lookup_mnt(path->mnt, dentry); 1355ea936aebSAl Viro if (mounted) { 1356c7105365SAl Viro path->mnt = &mounted->mnt; 1357ea936aebSAl Viro dentry = path->dentry = mounted->mnt.mnt_root; 1358a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1359ea936aebSAl Viro *seqp = read_seqcount_begin(&dentry->d_seq); 1360ea936aebSAl Viro *inode = dentry->d_inode; 136159430262SLinus Torvalds /* 1362ea936aebSAl Viro * We don't need to re-check ->d_seq after this 1363ea936aebSAl Viro * ->d_inode read - there will be an RCU delay 1364ea936aebSAl Viro * between mount hash removal and ->mnt_root 1365ea936aebSAl Viro * becoming unpinned. 136659430262SLinus Torvalds */ 1367ea936aebSAl Viro flags = dentry->d_flags; 1368ea936aebSAl Viro continue; 13699875cf80SDavid Howells } 1370ea936aebSAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1371ea936aebSAl Viro return false; 1372ea936aebSAl Viro } 1373ea936aebSAl Viro return !(flags & DCACHE_NEED_AUTOMOUNT); 1374ea936aebSAl Viro } 1375287548e4SAl Viro } 1376287548e4SAl Viro 1377db3c9adeSAl Viro static inline int handle_mounts(struct nameidata *nd, struct dentry *dentry, 1378db3c9adeSAl Viro struct path *path, struct inode **inode, 1379db3c9adeSAl Viro unsigned int *seqp) 1380bd7c4b50SAl Viro { 13819deed3ebSAl Viro bool jumped; 1382db3c9adeSAl Viro int ret; 1383bd7c4b50SAl Viro 1384db3c9adeSAl Viro path->mnt = nd->path.mnt; 1385db3c9adeSAl Viro path->dentry = dentry; 1386c153007bSAl Viro if (nd->flags & LOOKUP_RCU) { 1387c153007bSAl Viro unsigned int seq = *seqp; 1388c153007bSAl Viro if (unlikely(!*inode)) 1389c153007bSAl Viro return -ENOENT; 1390c153007bSAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 13919deed3ebSAl Viro return 0; 1392c153007bSAl Viro if (unlazy_child(nd, dentry, seq)) 1393c153007bSAl Viro return -ECHILD; 1394c153007bSAl Viro // *path might've been clobbered by __follow_mount_rcu() 1395c153007bSAl Viro path->mnt = nd->path.mnt; 1396c153007bSAl Viro path->dentry = dentry; 1397c153007bSAl Viro } 13989deed3ebSAl Viro ret = traverse_mounts(path, &jumped, &nd->total_link_count, nd->flags); 13999deed3ebSAl Viro if (jumped) { 14009deed3ebSAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 14019deed3ebSAl Viro ret = -EXDEV; 14029deed3ebSAl Viro else 14039deed3ebSAl Viro nd->flags |= LOOKUP_JUMPED; 14049deed3ebSAl Viro } 14059deed3ebSAl Viro if (unlikely(ret)) { 14069deed3ebSAl Viro dput(path->dentry); 14079deed3ebSAl Viro if (path->mnt != nd->path.mnt) 14089deed3ebSAl Viro mntput(path->mnt); 14099deed3ebSAl Viro } else { 1410bd7c4b50SAl Viro *inode = d_backing_inode(path->dentry); 1411bd7c4b50SAl Viro *seqp = 0; /* out of RCU mode, so the value doesn't matter */ 1412bd7c4b50SAl Viro } 1413bd7c4b50SAl Viro return ret; 1414bd7c4b50SAl Viro } 1415bd7c4b50SAl Viro 14169875cf80SDavid Howells /* 14179875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 14189875cf80SDavid Howells */ 14199875cf80SDavid Howells static void follow_mount(struct path *path) 14209875cf80SDavid Howells { 14219875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 14229875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 14239875cf80SDavid Howells if (!mounted) 14249875cf80SDavid Howells break; 14259875cf80SDavid Howells dput(path->dentry); 14269875cf80SDavid Howells mntput(path->mnt); 14279875cf80SDavid Howells path->mnt = mounted; 14289875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 14299875cf80SDavid Howells } 14309875cf80SDavid Howells } 14319875cf80SDavid Howells 14321da177e4SLinus Torvalds /* 1433f4fdace9SOleg Drokin * This looks up the name in dcache and possibly revalidates the found dentry. 1434f4fdace9SOleg Drokin * NULL is returned if the dentry does not exist in the cache. 1435baa03890SNick Piggin */ 1436e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1437e3c13928SAl Viro struct dentry *dir, 14386c51e513SAl Viro unsigned int flags) 1439baa03890SNick Piggin { 1440a89f8337SAl Viro struct dentry *dentry = d_lookup(dir, name); 1441bad61189SMiklos Szeredi if (dentry) { 1442a89f8337SAl Viro int error = d_revalidate(dentry, flags); 1443bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 144474ff0ffcSAl Viro if (!error) 14455542aa2fSEric W. Biederman d_invalidate(dentry); 1446bad61189SMiklos Szeredi dput(dentry); 144774ff0ffcSAl Viro return ERR_PTR(error); 1448bad61189SMiklos Szeredi } 1449bad61189SMiklos Szeredi } 1450baa03890SNick Piggin return dentry; 1451baa03890SNick Piggin } 1452baa03890SNick Piggin 1453baa03890SNick Piggin /* 1454a03ece5fSAl Viro * Parent directory has inode locked exclusive. This is one 1455a03ece5fSAl Viro * and only case when ->lookup() gets called on non in-lookup 1456a03ece5fSAl Viro * dentries - as the matter of fact, this only gets called 1457a03ece5fSAl Viro * when directory is guaranteed to have no in-lookup children 1458a03ece5fSAl Viro * at all. 145944396f4bSJosef Bacik */ 1460a03ece5fSAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 1461a03ece5fSAl Viro struct dentry *base, unsigned int flags) 146244396f4bSJosef Bacik { 1463a03ece5fSAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 146444396f4bSJosef Bacik struct dentry *old; 1465a03ece5fSAl Viro struct inode *dir = base->d_inode; 1466a03ece5fSAl Viro 1467a03ece5fSAl Viro if (dentry) 1468a03ece5fSAl Viro return dentry; 146944396f4bSJosef Bacik 147044396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1471a03ece5fSAl Viro if (unlikely(IS_DEADDIR(dir))) 147244396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1473a03ece5fSAl Viro 1474a03ece5fSAl Viro dentry = d_alloc(base, name); 1475a03ece5fSAl Viro if (unlikely(!dentry)) 1476a03ece5fSAl Viro return ERR_PTR(-ENOMEM); 147744396f4bSJosef Bacik 147872bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 147944396f4bSJosef Bacik if (unlikely(old)) { 148044396f4bSJosef Bacik dput(dentry); 148144396f4bSJosef Bacik dentry = old; 148244396f4bSJosef Bacik } 148344396f4bSJosef Bacik return dentry; 148444396f4bSJosef Bacik } 148544396f4bSJosef Bacik 148620e34357SAl Viro static struct dentry *lookup_fast(struct nameidata *nd, 148720e34357SAl Viro struct inode **inode, 1488254cf582SAl Viro unsigned *seqp) 14891da177e4SLinus Torvalds { 149031e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 14915a18fff2SAl Viro int status = 1; 14929875cf80SDavid Howells 14933cac260aSAl Viro /* 1494b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 14955d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 14965d0f49c1SAl Viro * going to fall back to non-racy lookup. 1497b04f784eSNick Piggin */ 149831e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 149931e6b01fSNick Piggin unsigned seq; 1500da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15015d0f49c1SAl Viro if (unlikely(!dentry)) { 15024675ac39SAl Viro if (unlazy_walk(nd)) 150320e34357SAl Viro return ERR_PTR(-ECHILD); 150420e34357SAl Viro return NULL; 15055d0f49c1SAl Viro } 15065a18fff2SAl Viro 150712f8ad4bSLinus Torvalds /* 150812f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 150912f8ad4bSLinus Torvalds * the dentry name information from lookup. 151012f8ad4bSLinus Torvalds */ 151163afdfc7SDavid Howells *inode = d_backing_inode(dentry); 15125d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 151320e34357SAl Viro return ERR_PTR(-ECHILD); 151412f8ad4bSLinus Torvalds 151512f8ad4bSLinus Torvalds /* 151612f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 151712f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 151812f8ad4bSLinus Torvalds * 151912f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 152012f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 152112f8ad4bSLinus Torvalds */ 15225d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 152320e34357SAl Viro return ERR_PTR(-ECHILD); 15245a18fff2SAl Viro 1525254cf582SAl Viro *seqp = seq; 15264ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 1527c153007bSAl Viro if (likely(status > 0)) 152820e34357SAl Viro return dentry; 15294675ac39SAl Viro if (unlazy_child(nd, dentry, seq)) 153020e34357SAl Viro return ERR_PTR(-ECHILD); 1531209a7fb2SAl Viro if (unlikely(status == -ECHILD)) 1532209a7fb2SAl Viro /* we'd been told to redo it in non-rcu mode */ 1533209a7fb2SAl Viro status = d_revalidate(dentry, nd->flags); 15345a18fff2SAl Viro } else { 1535e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 153681e6f520SAl Viro if (unlikely(!dentry)) 153720e34357SAl Viro return NULL; 15384ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15395d0f49c1SAl Viro } 15405a18fff2SAl Viro if (unlikely(status <= 0)) { 1541e9742b53SAl Viro if (!status) 15425d0f49c1SAl Viro d_invalidate(dentry); 15435a18fff2SAl Viro dput(dentry); 154420e34357SAl Viro return ERR_PTR(status); 15455a18fff2SAl Viro } 154620e34357SAl Viro return dentry; 1547697f514dSMiklos Szeredi } 1548697f514dSMiklos Szeredi 1549697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 155088d8331aSAl Viro static struct dentry *__lookup_slow(const struct qstr *name, 1551e3c13928SAl Viro struct dentry *dir, 1552e3c13928SAl Viro unsigned int flags) 1553697f514dSMiklos Szeredi { 155488d8331aSAl Viro struct dentry *dentry, *old; 15551936386eSAl Viro struct inode *inode = dir->d_inode; 1556d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 15571936386eSAl Viro 15581936386eSAl Viro /* Don't go there if it's already dead */ 155994bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 156088d8331aSAl Viro return ERR_PTR(-ENOENT); 156194bdd655SAl Viro again: 1562d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 156394bdd655SAl Viro if (IS_ERR(dentry)) 156488d8331aSAl Viro return dentry; 156594bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1566949a852eSAl Viro int error = d_revalidate(dentry, flags); 1567949a852eSAl Viro if (unlikely(error <= 0)) { 156894bdd655SAl Viro if (!error) { 1569949a852eSAl Viro d_invalidate(dentry); 1570949a852eSAl Viro dput(dentry); 157194bdd655SAl Viro goto again; 157294bdd655SAl Viro } 157394bdd655SAl Viro dput(dentry); 1574949a852eSAl Viro dentry = ERR_PTR(error); 1575949a852eSAl Viro } 157694bdd655SAl Viro } else { 15771936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 157885c7f810SAl Viro d_lookup_done(dentry); 15791936386eSAl Viro if (unlikely(old)) { 15801936386eSAl Viro dput(dentry); 15811936386eSAl Viro dentry = old; 1582949a852eSAl Viro } 1583949a852eSAl Viro } 1584e3c13928SAl Viro return dentry; 15851da177e4SLinus Torvalds } 15861da177e4SLinus Torvalds 158788d8331aSAl Viro static struct dentry *lookup_slow(const struct qstr *name, 158888d8331aSAl Viro struct dentry *dir, 158988d8331aSAl Viro unsigned int flags) 159088d8331aSAl Viro { 159188d8331aSAl Viro struct inode *inode = dir->d_inode; 159288d8331aSAl Viro struct dentry *res; 159388d8331aSAl Viro inode_lock_shared(inode); 159488d8331aSAl Viro res = __lookup_slow(name, dir, flags); 159588d8331aSAl Viro inode_unlock_shared(inode); 159688d8331aSAl Viro return res; 159788d8331aSAl Viro } 159888d8331aSAl Viro 159952094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 160052094c8aSAl Viro { 160152094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16024ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 160352094c8aSAl Viro if (err != -ECHILD) 160452094c8aSAl Viro return err; 16054675ac39SAl Viro if (unlazy_walk(nd)) 160652094c8aSAl Viro return -ECHILD; 160752094c8aSAl Viro } 16084ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 160952094c8aSAl Viro } 161052094c8aSAl Viro 1611b1a81972SAl Viro enum {WALK_TRAILING = 1, WALK_MORE = 2, WALK_NOFOLLOW = 4}; 1612b1a81972SAl Viro 161306708adbSAl Viro static const char *pick_link(struct nameidata *nd, struct path *link, 1614b1a81972SAl Viro struct inode *inode, unsigned seq, int flags) 1615d63ff28fSAl Viro { 16161cf2665bSAl Viro struct saved *last; 1617ad6cc4c3SAl Viro const char *res; 1618ad6cc4c3SAl Viro int error; 1619ad6cc4c3SAl Viro 1620756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1621626de996SAl Viro path_to_nameidata(link, nd); 162206708adbSAl Viro return ERR_PTR(-ELOOP); 1623626de996SAl Viro } 1624bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1625cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1626cd179f44SAl Viro mntget(link->mnt); 16277973387aSAl Viro } 1628626de996SAl Viro error = nd_alloc_stack(nd); 1629626de996SAl Viro if (unlikely(error)) { 1630bc40aee0SAl Viro if (error == -ECHILD) { 1631ad1633a1SAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 1632ad1633a1SAl Viro drop_links(nd); 1633ad1633a1SAl Viro nd->depth = 0; 1634ad1633a1SAl Viro nd->flags &= ~LOOKUP_RCU; 1635ad1633a1SAl Viro nd->path.mnt = NULL; 1636ad1633a1SAl Viro nd->path.dentry = NULL; 1637ad1633a1SAl Viro rcu_read_unlock(); 16384675ac39SAl Viro } else if (likely(unlazy_walk(nd)) == 0) 1639bc40aee0SAl Viro error = nd_alloc_stack(nd); 1640bc40aee0SAl Viro } 1641bc40aee0SAl Viro if (error) { 1642cd179f44SAl Viro path_put(link); 164306708adbSAl Viro return ERR_PTR(error); 1644626de996SAl Viro } 1645bc40aee0SAl Viro } 1646626de996SAl Viro 1647ab104923SAl Viro last = nd->stack + nd->depth++; 16481cf2665bSAl Viro last->link = *link; 1649fceef393SAl Viro clear_delayed_call(&last->done); 16500450b2d1SAl Viro last->seq = seq; 1651ad6cc4c3SAl Viro 1652b1a81972SAl Viro if (flags & WALK_TRAILING) { 1653ad6cc4c3SAl Viro error = may_follow_link(nd, inode); 1654ad6cc4c3SAl Viro if (unlikely(error)) 1655ad6cc4c3SAl Viro return ERR_PTR(error); 1656ad6cc4c3SAl Viro } 1657ad6cc4c3SAl Viro 1658ad6cc4c3SAl Viro if (unlikely(nd->flags & LOOKUP_NO_SYMLINKS)) 1659ad6cc4c3SAl Viro return ERR_PTR(-ELOOP); 1660ad6cc4c3SAl Viro 1661ad6cc4c3SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1662ad6cc4c3SAl Viro touch_atime(&last->link); 1663ad6cc4c3SAl Viro cond_resched(); 1664ad6cc4c3SAl Viro } else if (atime_needs_update(&last->link, inode)) { 1665ad6cc4c3SAl Viro if (unlikely(unlazy_walk(nd))) 1666ad6cc4c3SAl Viro return ERR_PTR(-ECHILD); 1667ad6cc4c3SAl Viro touch_atime(&last->link); 1668ad6cc4c3SAl Viro } 1669ad6cc4c3SAl Viro 1670ad6cc4c3SAl Viro error = security_inode_follow_link(link->dentry, inode, 1671ad6cc4c3SAl Viro nd->flags & LOOKUP_RCU); 1672ad6cc4c3SAl Viro if (unlikely(error)) 1673ad6cc4c3SAl Viro return ERR_PTR(error); 1674ad6cc4c3SAl Viro 1675ad6cc4c3SAl Viro res = READ_ONCE(inode->i_link); 1676ad6cc4c3SAl Viro if (!res) { 1677ad6cc4c3SAl Viro const char * (*get)(struct dentry *, struct inode *, 1678ad6cc4c3SAl Viro struct delayed_call *); 1679ad6cc4c3SAl Viro get = inode->i_op->get_link; 1680ad6cc4c3SAl Viro if (nd->flags & LOOKUP_RCU) { 1681ad6cc4c3SAl Viro res = get(NULL, inode, &last->done); 1682ad6cc4c3SAl Viro if (res == ERR_PTR(-ECHILD)) { 1683ad6cc4c3SAl Viro if (unlikely(unlazy_walk(nd))) 1684ad6cc4c3SAl Viro return ERR_PTR(-ECHILD); 1685ad6cc4c3SAl Viro res = get(link->dentry, inode, &last->done); 1686ad6cc4c3SAl Viro } 1687ad6cc4c3SAl Viro } else { 1688ad6cc4c3SAl Viro res = get(link->dentry, inode, &last->done); 1689ad6cc4c3SAl Viro } 1690ad6cc4c3SAl Viro if (!res) 1691ad6cc4c3SAl Viro goto all_done; 1692ad6cc4c3SAl Viro if (IS_ERR(res)) 1693ad6cc4c3SAl Viro return res; 1694ad6cc4c3SAl Viro } 1695ad6cc4c3SAl Viro if (*res == '/') { 1696ad6cc4c3SAl Viro error = nd_jump_root(nd); 1697ad6cc4c3SAl Viro if (unlikely(error)) 1698ad6cc4c3SAl Viro return ERR_PTR(error); 1699ad6cc4c3SAl Viro while (unlikely(*++res == '/')) 1700ad6cc4c3SAl Viro ; 1701ad6cc4c3SAl Viro } 1702ad6cc4c3SAl Viro if (*res) 1703ad6cc4c3SAl Viro return res; 1704ad6cc4c3SAl Viro all_done: // pure jump 1705ad6cc4c3SAl Viro put_link(nd); 1706ad6cc4c3SAl Viro return NULL; 1707d63ff28fSAl Viro } 1708d63ff28fSAl Viro 17093ddcd056SLinus Torvalds /* 17103ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 17113ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 17123ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 17133ddcd056SLinus Torvalds * for the common case. 17143ddcd056SLinus Torvalds */ 1715b0417d2cSAl Viro static const char *step_into(struct nameidata *nd, int flags, 1716cbae4d12SAl Viro struct dentry *dentry, struct inode *inode, unsigned seq) 17173ddcd056SLinus Torvalds { 1718cbae4d12SAl Viro struct path path; 1719cbae4d12SAl Viro int err = handle_mounts(nd, dentry, &path, &inode, &seq); 1720cbae4d12SAl Viro 1721cbae4d12SAl Viro if (err < 0) 1722b0417d2cSAl Viro return ERR_PTR(err); 1723cbae4d12SAl Viro if (likely(!d_is_symlink(path.dentry)) || 17248c4efe22SAl Viro ((flags & WALK_TRAILING) && !(nd->flags & LOOKUP_FOLLOW)) || 1725aca2903eSAl Viro (flags & WALK_NOFOLLOW)) { 17268f64fb1cSAl Viro /* not a symlink or should not follow */ 1727cbae4d12SAl Viro path_to_nameidata(&path, nd); 17288f64fb1cSAl Viro nd->inode = inode; 17298f64fb1cSAl Viro nd->seq = seq; 1730b0417d2cSAl Viro return NULL; 17318f64fb1cSAl Viro } 1732a7f77542SAl Viro /* make sure that d_is_symlink above matches inode */ 1733a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 1734cbae4d12SAl Viro if (read_seqcount_retry(&path.dentry->d_seq, seq)) 1735b0417d2cSAl Viro return ERR_PTR(-ECHILD); 1736a7f77542SAl Viro } 1737b1a81972SAl Viro return pick_link(nd, &path, inode, seq, flags); 17383ddcd056SLinus Torvalds } 17393ddcd056SLinus Torvalds 1740c2df1968SAl Viro static struct dentry *follow_dotdot_rcu(struct nameidata *nd, 1741c2df1968SAl Viro struct inode **inodep, 1742c2df1968SAl Viro unsigned *seqp) 1743957dd41dSAl Viro { 174412487f30SAl Viro struct dentry *parent, *old; 1745957dd41dSAl Viro 174612487f30SAl Viro if (path_equal(&nd->path, &nd->root)) 174712487f30SAl Viro goto in_root; 174812487f30SAl Viro if (unlikely(nd->path.dentry == nd->path.mnt->mnt_root)) { 17497ef482faSAl Viro struct path path; 1750efe772d6SAl Viro unsigned seq; 17517ef482faSAl Viro if (!choose_mountpoint_rcu(real_mount(nd->path.mnt), 17527ef482faSAl Viro &nd->root, &path, &seq)) 175312487f30SAl Viro goto in_root; 1754efe772d6SAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 1755efe772d6SAl Viro return ERR_PTR(-ECHILD); 1756efe772d6SAl Viro nd->path = path; 1757efe772d6SAl Viro nd->inode = path.dentry->d_inode; 1758efe772d6SAl Viro nd->seq = seq; 1759efe772d6SAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1760efe772d6SAl Viro return ERR_PTR(-ECHILD); 1761efe772d6SAl Viro /* we know that mountpoint was pinned */ 1762957dd41dSAl Viro } 176312487f30SAl Viro old = nd->path.dentry; 176412487f30SAl Viro parent = old->d_parent; 176512487f30SAl Viro *inodep = parent->d_inode; 176612487f30SAl Viro *seqp = read_seqcount_begin(&parent->d_seq); 176712487f30SAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 176812487f30SAl Viro return ERR_PTR(-ECHILD); 176912487f30SAl Viro if (unlikely(!path_connected(nd->path.mnt, parent))) 177012487f30SAl Viro return ERR_PTR(-ECHILD); 177112487f30SAl Viro return parent; 177212487f30SAl Viro in_root: 1773efe772d6SAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1774efe772d6SAl Viro return ERR_PTR(-ECHILD); 1775957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_BENEATH)) 17767521f22bSAl Viro return ERR_PTR(-ECHILD); 1777c2df1968SAl Viro return NULL; 1778957dd41dSAl Viro } 1779957dd41dSAl Viro 1780c2df1968SAl Viro static struct dentry *follow_dotdot(struct nameidata *nd, 1781c2df1968SAl Viro struct inode **inodep, 1782c2df1968SAl Viro unsigned *seqp) 1783957dd41dSAl Viro { 178412487f30SAl Viro struct dentry *parent; 178512487f30SAl Viro 1786957dd41dSAl Viro if (path_equal(&nd->path, &nd->root)) 178712487f30SAl Viro goto in_root; 178812487f30SAl Viro if (unlikely(nd->path.dentry == nd->path.mnt->mnt_root)) { 17892aa38470SAl Viro struct path path; 17902aa38470SAl Viro 17912aa38470SAl Viro if (!choose_mountpoint(real_mount(nd->path.mnt), 17922aa38470SAl Viro &nd->root, &path)) 179312487f30SAl Viro goto in_root; 1794165200d6SAl Viro path_put(&nd->path); 1795165200d6SAl Viro nd->path = path; 17962aa38470SAl Viro nd->inode = path.dentry->d_inode; 1797165200d6SAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 1798165200d6SAl Viro return ERR_PTR(-EXDEV); 179912487f30SAl Viro } 1800957dd41dSAl Viro /* rare case of legitimate dget_parent()... */ 180112487f30SAl Viro parent = dget_parent(nd->path.dentry); 1802957dd41dSAl Viro if (unlikely(!path_connected(nd->path.mnt, parent))) { 1803957dd41dSAl Viro dput(parent); 18047521f22bSAl Viro return ERR_PTR(-ENOENT); 1805957dd41dSAl Viro } 1806c2df1968SAl Viro *seqp = 0; 1807c2df1968SAl Viro *inodep = parent->d_inode; 1808c2df1968SAl Viro return parent; 180912487f30SAl Viro 181012487f30SAl Viro in_root: 1811957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_BENEATH)) 18127521f22bSAl Viro return ERR_PTR(-EXDEV); 1813c2df1968SAl Viro dget(nd->path.dentry); 1814c2df1968SAl Viro return NULL; 1815957dd41dSAl Viro } 1816957dd41dSAl Viro 18177521f22bSAl Viro static const char *handle_dots(struct nameidata *nd, int type) 1818957dd41dSAl Viro { 1819957dd41dSAl Viro if (type == LAST_DOTDOT) { 18207521f22bSAl Viro const char *error = NULL; 1821c2df1968SAl Viro struct dentry *parent; 1822c2df1968SAl Viro struct inode *inode; 1823c2df1968SAl Viro unsigned seq; 1824957dd41dSAl Viro 1825957dd41dSAl Viro if (!nd->root.mnt) { 18267521f22bSAl Viro error = ERR_PTR(set_root(nd)); 1827957dd41dSAl Viro if (error) 1828957dd41dSAl Viro return error; 1829957dd41dSAl Viro } 1830957dd41dSAl Viro if (nd->flags & LOOKUP_RCU) 1831c2df1968SAl Viro parent = follow_dotdot_rcu(nd, &inode, &seq); 1832957dd41dSAl Viro else 1833c2df1968SAl Viro parent = follow_dotdot(nd, &inode, &seq); 1834c2df1968SAl Viro if (IS_ERR(parent)) 1835c2df1968SAl Viro return ERR_CAST(parent); 1836c2df1968SAl Viro if (unlikely(!parent)) 1837c2df1968SAl Viro error = step_into(nd, WALK_NOFOLLOW, 1838c2df1968SAl Viro nd->path.dentry, nd->inode, nd->seq); 1839c2df1968SAl Viro else 1840c2df1968SAl Viro error = step_into(nd, WALK_NOFOLLOW, 1841c2df1968SAl Viro parent, inode, seq); 1842c2df1968SAl Viro if (unlikely(error)) 1843957dd41dSAl Viro return error; 1844957dd41dSAl Viro 1845957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) { 1846957dd41dSAl Viro /* 1847957dd41dSAl Viro * If there was a racing rename or mount along our 1848957dd41dSAl Viro * path, then we can't be sure that ".." hasn't jumped 1849957dd41dSAl Viro * above nd->root (and so userspace should retry or use 1850957dd41dSAl Viro * some fallback). 1851957dd41dSAl Viro */ 1852957dd41dSAl Viro smp_rmb(); 1853957dd41dSAl Viro if (unlikely(__read_seqcount_retry(&mount_lock.seqcount, nd->m_seq))) 18547521f22bSAl Viro return ERR_PTR(-EAGAIN); 1855957dd41dSAl Viro if (unlikely(__read_seqcount_retry(&rename_lock.seqcount, nd->r_seq))) 18567521f22bSAl Viro return ERR_PTR(-EAGAIN); 1857957dd41dSAl Viro } 1858957dd41dSAl Viro } 18597521f22bSAl Viro return NULL; 1860957dd41dSAl Viro } 1861957dd41dSAl Viro 186292d27016SAl Viro static const char *walk_component(struct nameidata *nd, int flags) 1863ce57dfc1SAl Viro { 1864db3c9adeSAl Viro struct dentry *dentry; 1865ce57dfc1SAl Viro struct inode *inode; 1866254cf582SAl Viro unsigned seq; 1867ce57dfc1SAl Viro /* 1868ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1869ce57dfc1SAl Viro * to be able to know about the current root directory and 1870ce57dfc1SAl Viro * parent relationships. 1871ce57dfc1SAl Viro */ 18724693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 18731c4ff1a8SAl Viro if (!(flags & WALK_MORE) && nd->depth) 18744693a547SAl Viro put_link(nd); 18757521f22bSAl Viro return handle_dots(nd, nd->last_type); 18764693a547SAl Viro } 187720e34357SAl Viro dentry = lookup_fast(nd, &inode, &seq); 187820e34357SAl Viro if (IS_ERR(dentry)) 187992d27016SAl Viro return ERR_CAST(dentry); 188020e34357SAl Viro if (unlikely(!dentry)) { 1881db3c9adeSAl Viro dentry = lookup_slow(&nd->last, nd->path.dentry, nd->flags); 1882db3c9adeSAl Viro if (IS_ERR(dentry)) 188392d27016SAl Viro return ERR_CAST(dentry); 188420e34357SAl Viro } 188556676ec3SAl Viro if (!(flags & WALK_MORE) && nd->depth) 188656676ec3SAl Viro put_link(nd); 1887b0417d2cSAl Viro return step_into(nd, flags, dentry, inode, seq); 1888ce57dfc1SAl Viro } 1889ce57dfc1SAl Viro 18901da177e4SLinus Torvalds /* 1891bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1892bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1893bfcfaa77SLinus Torvalds * 1894bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1895bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1896bfcfaa77SLinus Torvalds * fast. 1897bfcfaa77SLinus Torvalds * 1898bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1899bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1900bfcfaa77SLinus Torvalds * crossing operation. 1901bfcfaa77SLinus Torvalds * 1902bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1903bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1904bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1905bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1906bfcfaa77SLinus Torvalds */ 1907bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1908bfcfaa77SLinus Torvalds 1909f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1910bfcfaa77SLinus Torvalds 1911468a9428SGeorge Spelvin #ifdef HASH_MIX 1912bfcfaa77SLinus Torvalds 1913468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1914468a9428SGeorge Spelvin 1915468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 19162a18da7aSGeorge Spelvin /* 19172a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 19182a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 19192a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 19202a18da7aSGeorge Spelvin * and no temporaries. 19212a18da7aSGeorge Spelvin * 19222a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 19232a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 19242a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 19252a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 19262a18da7aSGeorge Spelvin * 19272a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 19282a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 19292a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 19302a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 19312a18da7aSGeorge Spelvin * 19322a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 19332a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 19342a18da7aSGeorge Spelvin * toggling any given output bit. 19352a18da7aSGeorge Spelvin * 19362a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 19372a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 19382a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 19392a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 19402a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 19412a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 19422a18da7aSGeorge Spelvin * Perfect: 8192 258048 19432a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 19442a18da7aSGeorge Spelvin */ 19452a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 19462a18da7aSGeorge Spelvin ( x ^= (a), \ 19472a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 19482a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 19492a18da7aSGeorge Spelvin y *= 9 ) 1950bfcfaa77SLinus Torvalds 19510fed3ac8SGeorge Spelvin /* 19522a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 19532a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 19542a18da7aSGeorge Spelvin * work done before the hash value is used. 19550fed3ac8SGeorge Spelvin */ 19562a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 19570fed3ac8SGeorge Spelvin { 19582a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 19592a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 19602a18da7aSGeorge Spelvin return y >> 32; 19610fed3ac8SGeorge Spelvin } 19620fed3ac8SGeorge Spelvin 1963bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1964bfcfaa77SLinus Torvalds 19652a18da7aSGeorge Spelvin /* 19662a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 19672a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 19682a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 19692a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 19702a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 19712a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 19722a18da7aSGeorge Spelvin * Perfect: 2048 31744 19732a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 19742a18da7aSGeorge Spelvin */ 19752a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 19762a18da7aSGeorge Spelvin ( x ^= (a), \ 19772a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 19782a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 19792a18da7aSGeorge Spelvin y *= 9 ) 1980bfcfaa77SLinus Torvalds 19812a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 19820fed3ac8SGeorge Spelvin { 19832a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 19842a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 19850fed3ac8SGeorge Spelvin } 19860fed3ac8SGeorge Spelvin 1987bfcfaa77SLinus Torvalds #endif 1988bfcfaa77SLinus Torvalds 19892a18da7aSGeorge Spelvin /* 19902a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 19912a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 19922a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 19932a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 19942a18da7aSGeorge Spelvin * finds the delimiter after the name. 19952a18da7aSGeorge Spelvin */ 19968387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 1997bfcfaa77SLinus Torvalds { 19988387ff25SLinus Torvalds unsigned long a, x = 0, y = (unsigned long)salt; 1999bfcfaa77SLinus Torvalds 2000bfcfaa77SLinus Torvalds for (;;) { 2001fcfd2fbfSGeorge Spelvin if (!len) 2002fcfd2fbfSGeorge Spelvin goto done; 2003e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 2004bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 2005bfcfaa77SLinus Torvalds break; 20062a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2007bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 2008bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 2009bfcfaa77SLinus Torvalds } 20102a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 2011bfcfaa77SLinus Torvalds done: 20122a18da7aSGeorge Spelvin return fold_hash(x, y); 2013bfcfaa77SLinus Torvalds } 2014bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 2015bfcfaa77SLinus Torvalds 2016fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 20178387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2018fcfd2fbfSGeorge Spelvin { 20198387ff25SLinus Torvalds unsigned long a = 0, x = 0, y = (unsigned long)salt; 20208387ff25SLinus Torvalds unsigned long adata, mask, len; 2021fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 2022fcfd2fbfSGeorge Spelvin 20238387ff25SLinus Torvalds len = 0; 20248387ff25SLinus Torvalds goto inside; 20258387ff25SLinus Torvalds 2026fcfd2fbfSGeorge Spelvin do { 20272a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2028fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 20298387ff25SLinus Torvalds inside: 2030fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 2031fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 2032fcfd2fbfSGeorge Spelvin 2033fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 2034fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 20352a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 2036fcfd2fbfSGeorge Spelvin 20372a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2038fcfd2fbfSGeorge Spelvin } 2039fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2040fcfd2fbfSGeorge Spelvin 2041bfcfaa77SLinus Torvalds /* 2042bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 2043d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 2044bfcfaa77SLinus Torvalds */ 20458387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2046bfcfaa77SLinus Torvalds { 20478387ff25SLinus Torvalds unsigned long a = 0, b, x = 0, y = (unsigned long)salt; 20488387ff25SLinus Torvalds unsigned long adata, bdata, mask, len; 204936126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 2050bfcfaa77SLinus Torvalds 20518387ff25SLinus Torvalds len = 0; 20528387ff25SLinus Torvalds goto inside; 20538387ff25SLinus Torvalds 2054bfcfaa77SLinus Torvalds do { 20552a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2056bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 20578387ff25SLinus Torvalds inside: 2058e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 205936126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 206036126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 2061bfcfaa77SLinus Torvalds 206236126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 206336126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 206436126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 20652a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 206636126f8fSLinus Torvalds 20672a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2068bfcfaa77SLinus Torvalds } 2069bfcfaa77SLinus Torvalds 20702a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 2071bfcfaa77SLinus Torvalds 2072fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 20738387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 20740145acc2SLinus Torvalds { 20758387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 20760145acc2SLinus Torvalds while (len--) 2077fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 20780145acc2SLinus Torvalds return end_name_hash(hash); 20790145acc2SLinus Torvalds } 2080ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 20810145acc2SLinus Torvalds 2082fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 20838387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2084fcfd2fbfSGeorge Spelvin { 20858387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2086fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 2087fcfd2fbfSGeorge Spelvin 2088fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 2089e0ab7af9SGeorge Spelvin while (c) { 2090fcfd2fbfSGeorge Spelvin len++; 2091fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 2092fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 2093e0ab7af9SGeorge Spelvin } 2094fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 2095fcfd2fbfSGeorge Spelvin } 2096f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2097fcfd2fbfSGeorge Spelvin 20983ddcd056SLinus Torvalds /* 2099200e9ef7SLinus Torvalds * We know there's a real path component here of at least 2100200e9ef7SLinus Torvalds * one character. 2101200e9ef7SLinus Torvalds */ 21028387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2103200e9ef7SLinus Torvalds { 21048387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2105200e9ef7SLinus Torvalds unsigned long len = 0, c; 2106200e9ef7SLinus Torvalds 2107200e9ef7SLinus Torvalds c = (unsigned char)*name; 2108200e9ef7SLinus Torvalds do { 2109200e9ef7SLinus Torvalds len++; 2110200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2111200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2112200e9ef7SLinus Torvalds } while (c && c != '/'); 2113d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2114200e9ef7SLinus Torvalds } 2115200e9ef7SLinus Torvalds 2116bfcfaa77SLinus Torvalds #endif 2117bfcfaa77SLinus Torvalds 2118200e9ef7SLinus Torvalds /* 21191da177e4SLinus Torvalds * Name resolution. 2120ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2121ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 21221da177e4SLinus Torvalds * 2123ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2124ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 21251da177e4SLinus Torvalds */ 21266de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 21271da177e4SLinus Torvalds { 2128d8d4611aSAl Viro int depth = 0; // depth <= nd->depth 21291da177e4SLinus Torvalds int err; 21301da177e4SLinus Torvalds 2131b4c03536SAl Viro nd->last_type = LAST_ROOT; 2132c108837eSAl Viro nd->flags |= LOOKUP_PARENT; 21339b5858e9SAl Viro if (IS_ERR(name)) 21349b5858e9SAl Viro return PTR_ERR(name); 21351da177e4SLinus Torvalds while (*name=='/') 21361da177e4SLinus Torvalds name++; 21371da177e4SLinus Torvalds if (!*name) 21389e18f10aSAl Viro return 0; 21391da177e4SLinus Torvalds 21401da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 21411da177e4SLinus Torvalds for(;;) { 214292d27016SAl Viro const char *link; 2143d6bb3e90SLinus Torvalds u64 hash_len; 2144fe479a58SAl Viro int type; 21451da177e4SLinus Torvalds 214652094c8aSAl Viro err = may_lookup(nd); 21471da177e4SLinus Torvalds if (err) 21483595e234SAl Viro return err; 21491da177e4SLinus Torvalds 21508387ff25SLinus Torvalds hash_len = hash_name(nd->path.dentry, name); 21511da177e4SLinus Torvalds 2152fe479a58SAl Viro type = LAST_NORM; 2153d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2154fe479a58SAl Viro case 2: 2155200e9ef7SLinus Torvalds if (name[1] == '.') { 2156fe479a58SAl Viro type = LAST_DOTDOT; 215716c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 215816c2cd71SAl Viro } 2159fe479a58SAl Viro break; 2160fe479a58SAl Viro case 1: 2161fe479a58SAl Viro type = LAST_DOT; 2162fe479a58SAl Viro } 21635a202bcdSAl Viro if (likely(type == LAST_NORM)) { 21645a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 216516c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 21665a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2167a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2168da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 21695a202bcdSAl Viro if (err < 0) 21703595e234SAl Viro return err; 2171d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2172d6bb3e90SLinus Torvalds name = this.name; 21735a202bcdSAl Viro } 21745a202bcdSAl Viro } 2175fe479a58SAl Viro 2176d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2177d6bb3e90SLinus Torvalds nd->last.name = name; 21785f4a6a69SAl Viro nd->last_type = type; 21795f4a6a69SAl Viro 2180d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2181d6bb3e90SLinus Torvalds if (!*name) 2182bdf6cbf1SAl Viro goto OK; 2183200e9ef7SLinus Torvalds /* 2184200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2185200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2186200e9ef7SLinus Torvalds */ 2187200e9ef7SLinus Torvalds do { 2188d6bb3e90SLinus Torvalds name++; 2189d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 21908620c238SAl Viro if (unlikely(!*name)) { 21918620c238SAl Viro OK: 2192d8d4611aSAl Viro /* pathname or trailing symlink, done */ 2193c108837eSAl Viro if (!depth) { 2194c108837eSAl Viro nd->flags &= ~LOOKUP_PARENT; 21958620c238SAl Viro return 0; 2196c108837eSAl Viro } 21978620c238SAl Viro /* last component of nested symlink */ 2198d8d4611aSAl Viro name = nd->stack[--depth].name; 21998c4efe22SAl Viro link = walk_component(nd, 0); 22001c4ff1a8SAl Viro } else { 22011c4ff1a8SAl Viro /* not the last component */ 22028c4efe22SAl Viro link = walk_component(nd, WALK_MORE); 22038620c238SAl Viro } 220492d27016SAl Viro if (unlikely(link)) { 220592d27016SAl Viro if (IS_ERR(link)) 220692d27016SAl Viro return PTR_ERR(link); 220792d27016SAl Viro /* a symlink to follow */ 2208d8d4611aSAl Viro nd->stack[depth++].name = name; 220992d27016SAl Viro name = link; 22109e18f10aSAl Viro continue; 221148c8b0c5SAl Viro } 221297242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 221397242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 22144675ac39SAl Viro if (unlazy_walk(nd)) 221597242f99SAl Viro return -ECHILD; 221697242f99SAl Viro } 22173595e234SAl Viro return -ENOTDIR; 22185f4a6a69SAl Viro } 2219ce57dfc1SAl Viro } 222097242f99SAl Viro } 22211da177e4SLinus Torvalds 2222edc2b1daSAl Viro /* must be paired with terminate_walk() */ 2223c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 222431e6b01fSNick Piggin { 2225740a1678SAleksa Sarai int error; 2226c8a53ee5SAl Viro const char *s = nd->name->name; 222731e6b01fSNick Piggin 2228c0eb027eSLinus Torvalds if (!*s) 2229c0eb027eSLinus Torvalds flags &= ~LOOKUP_RCU; 2230edc2b1daSAl Viro if (flags & LOOKUP_RCU) 2231edc2b1daSAl Viro rcu_read_lock(); 2232c0eb027eSLinus Torvalds 2233c108837eSAl Viro nd->flags = flags | LOOKUP_JUMPED; 223431e6b01fSNick Piggin nd->depth = 0; 2235ab87f9a5SAleksa Sarai 2236ab87f9a5SAleksa Sarai nd->m_seq = __read_seqcount_begin(&mount_lock.seqcount); 2237ab87f9a5SAleksa Sarai nd->r_seq = __read_seqcount_begin(&rename_lock.seqcount); 2238ab87f9a5SAleksa Sarai smp_rmb(); 2239ab87f9a5SAleksa Sarai 22405b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2241b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2242b18825a7SDavid Howells struct inode *inode = root->d_inode; 224393893862SAl Viro if (*s && unlikely(!d_can_lookup(root))) 2244368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 22455b6ca027SAl Viro nd->path = nd->root; 22465b6ca027SAl Viro nd->inode = inode; 22475b6ca027SAl Viro if (flags & LOOKUP_RCU) { 2248ab87f9a5SAleksa Sarai nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22498f47a016SAl Viro nd->root_seq = nd->seq; 22505b6ca027SAl Viro } else { 22515b6ca027SAl Viro path_get(&nd->path); 22525b6ca027SAl Viro } 2253368ee9baSAl Viro return s; 22545b6ca027SAl Viro } 22555b6ca027SAl Viro 225631e6b01fSNick Piggin nd->root.mnt = NULL; 2257248fb5b9SAl Viro nd->path.mnt = NULL; 2258248fb5b9SAl Viro nd->path.dentry = NULL; 225931e6b01fSNick Piggin 22608db52c7eSAleksa Sarai /* Absolute pathname -- fetch the root (LOOKUP_IN_ROOT uses nd->dfd). */ 22618db52c7eSAleksa Sarai if (*s == '/' && !(flags & LOOKUP_IN_ROOT)) { 2262740a1678SAleksa Sarai error = nd_jump_root(nd); 2263740a1678SAleksa Sarai if (unlikely(error)) 2264740a1678SAleksa Sarai return ERR_PTR(error); 2265ef55d917SAl Viro return s; 22668db52c7eSAleksa Sarai } 22678db52c7eSAleksa Sarai 22688db52c7eSAleksa Sarai /* Relative pathname -- get the starting-point it is relative to. */ 22698db52c7eSAleksa Sarai if (nd->dfd == AT_FDCWD) { 2270e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 227131e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2272c28cc364SNick Piggin unsigned seq; 227331e6b01fSNick Piggin 2274c28cc364SNick Piggin do { 2275c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 227631e6b01fSNick Piggin nd->path = fs->pwd; 2277ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2278c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2279c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2280e41f7d4eSAl Viro } else { 2281e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2282ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2283e41f7d4eSAl Viro } 228431e6b01fSNick Piggin } else { 2285582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2286c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 228731e6b01fSNick Piggin struct dentry *dentry; 228831e6b01fSNick Piggin 22892903ff01SAl Viro if (!f.file) 2290368ee9baSAl Viro return ERR_PTR(-EBADF); 229131e6b01fSNick Piggin 22922903ff01SAl Viro dentry = f.file->f_path.dentry; 229331e6b01fSNick Piggin 2294edc2b1daSAl Viro if (*s && unlikely(!d_can_lookup(dentry))) { 22952903ff01SAl Viro fdput(f); 2296368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2297f52e0c11SAl Viro } 22982903ff01SAl Viro 22992903ff01SAl Viro nd->path = f.file->f_path; 2300e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 230134a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 230234a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 23035590ff0dSUlrich Drepper } else { 23042903ff01SAl Viro path_get(&nd->path); 230534a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 23061da177e4SLinus Torvalds } 230734a26b99SAl Viro fdput(f); 2308e41f7d4eSAl Viro } 23098db52c7eSAleksa Sarai 2310adb21d2bSAleksa Sarai /* For scoped-lookups we need to set the root to the dirfd as well. */ 2311adb21d2bSAleksa Sarai if (flags & LOOKUP_IS_SCOPED) { 2312adb21d2bSAleksa Sarai nd->root = nd->path; 2313adb21d2bSAleksa Sarai if (flags & LOOKUP_RCU) { 2314adb21d2bSAleksa Sarai nd->root_seq = nd->seq; 2315adb21d2bSAleksa Sarai } else { 2316adb21d2bSAleksa Sarai path_get(&nd->root); 2317adb21d2bSAleksa Sarai nd->flags |= LOOKUP_ROOT_GRABBED; 2318adb21d2bSAleksa Sarai } 2319adb21d2bSAleksa Sarai } 2320adb21d2bSAleksa Sarai return s; 23219b4a9b14SAl Viro } 23229b4a9b14SAl Viro 23231ccac622SAl Viro static inline const char *lookup_last(struct nameidata *nd) 232495fa25d9SAl Viro { 2325bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2326bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2327bd92d7feSAl Viro 2328c108837eSAl Viro return walk_component(nd, WALK_TRAILING); 2329bd92d7feSAl Viro } 2330bd92d7feSAl Viro 23314f757f3cSAl Viro static int handle_lookup_down(struct nameidata *nd) 23324f757f3cSAl Viro { 2333c153007bSAl Viro if (!(nd->flags & LOOKUP_RCU)) 2334db3c9adeSAl Viro dget(nd->path.dentry); 2335b0417d2cSAl Viro return PTR_ERR(step_into(nd, WALK_NOFOLLOW, 2336b0417d2cSAl Viro nd->path.dentry, nd->inode, nd->seq)); 23374f757f3cSAl Viro } 23384f757f3cSAl Viro 23399b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2340c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 23419b4a9b14SAl Viro { 2342c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2343bd92d7feSAl Viro int err; 234431e6b01fSNick Piggin 23459b5858e9SAl Viro if (unlikely(flags & LOOKUP_DOWN) && !IS_ERR(s)) { 23464f757f3cSAl Viro err = handle_lookup_down(nd); 23475f336e72SAl Viro if (unlikely(err < 0)) 23485f336e72SAl Viro s = ERR_PTR(err); 23494f757f3cSAl Viro } 23504f757f3cSAl Viro 23511ccac622SAl Viro while (!(err = link_path_walk(s, nd)) && 23521ccac622SAl Viro (s = lookup_last(nd)) != NULL) 23531ccac622SAl Viro ; 23549f1fafeeSAl Viro if (!err) 23559f1fafeeSAl Viro err = complete_walk(nd); 2356bd92d7feSAl Viro 2357deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2358deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2359bd23a539SAl Viro err = -ENOTDIR; 2360161aff1dSAl Viro if (!err && unlikely(nd->flags & LOOKUP_MOUNTPOINT)) { 2361161aff1dSAl Viro err = handle_lookup_down(nd); 2362161aff1dSAl Viro nd->flags &= ~LOOKUP_JUMPED; // no d_weak_revalidate(), please... 2363161aff1dSAl Viro } 2364625b6d10SAl Viro if (!err) { 2365625b6d10SAl Viro *path = nd->path; 2366625b6d10SAl Viro nd->path.mnt = NULL; 2367625b6d10SAl Viro nd->path.dentry = NULL; 2368625b6d10SAl Viro } 2369deb106c6SAl Viro terminate_walk(nd); 2370bd92d7feSAl Viro return err; 237131e6b01fSNick Piggin } 237231e6b01fSNick Piggin 237331d921c7SDavid Howells int filename_lookup(int dfd, struct filename *name, unsigned flags, 23749ad1aaa6SAl Viro struct path *path, struct path *root) 2375873f1eedSJeff Layton { 2376894bc8c4SAl Viro int retval; 23779883d185SAl Viro struct nameidata nd; 2378abc9f5beSAl Viro if (IS_ERR(name)) 2379abc9f5beSAl Viro return PTR_ERR(name); 23809ad1aaa6SAl Viro if (unlikely(root)) { 23819ad1aaa6SAl Viro nd.root = *root; 23829ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 23839ad1aaa6SAl Viro } 23849883d185SAl Viro set_nameidata(&nd, dfd, name); 2385c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2386873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2387c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2388873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2389c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2390873f1eedSJeff Layton 2391873f1eedSJeff Layton if (likely(!retval)) 2392161aff1dSAl Viro audit_inode(name, path->dentry, 2393161aff1dSAl Viro flags & LOOKUP_MOUNTPOINT ? AUDIT_INODE_NOEVAL : 0); 23949883d185SAl Viro restore_nameidata(); 2395e4bd1c1aSAl Viro putname(name); 2396873f1eedSJeff Layton return retval; 2397873f1eedSJeff Layton } 2398873f1eedSJeff Layton 23998bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2400c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2401391172c4SAl Viro struct path *parent) 24028bcb77faSAl Viro { 2403c8a53ee5SAl Viro const char *s = path_init(nd, flags); 24049b5858e9SAl Viro int err = link_path_walk(s, nd); 24058bcb77faSAl Viro if (!err) 24068bcb77faSAl Viro err = complete_walk(nd); 2407391172c4SAl Viro if (!err) { 2408391172c4SAl Viro *parent = nd->path; 2409391172c4SAl Viro nd->path.mnt = NULL; 2410391172c4SAl Viro nd->path.dentry = NULL; 2411391172c4SAl Viro } 2412deb106c6SAl Viro terminate_walk(nd); 24138bcb77faSAl Viro return err; 24148bcb77faSAl Viro } 24158bcb77faSAl Viro 24165c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2417391172c4SAl Viro unsigned int flags, struct path *parent, 2418391172c4SAl Viro struct qstr *last, int *type) 24198bcb77faSAl Viro { 24208bcb77faSAl Viro int retval; 24219883d185SAl Viro struct nameidata nd; 24228bcb77faSAl Viro 24235c31b6ceSAl Viro if (IS_ERR(name)) 24245c31b6ceSAl Viro return name; 24259883d185SAl Viro set_nameidata(&nd, dfd, name); 2426c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 24278bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2428c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 24298bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2430c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2431391172c4SAl Viro if (likely(!retval)) { 2432391172c4SAl Viro *last = nd.last; 2433391172c4SAl Viro *type = nd.last_type; 2434c9b07eabSAl Viro audit_inode(name, parent->dentry, AUDIT_INODE_PARENT); 24355c31b6ceSAl Viro } else { 24365c31b6ceSAl Viro putname(name); 24375c31b6ceSAl Viro name = ERR_PTR(retval); 2438391172c4SAl Viro } 24399883d185SAl Viro restore_nameidata(); 24405c31b6ceSAl Viro return name; 24418bcb77faSAl Viro } 24428bcb77faSAl Viro 244379714f72SAl Viro /* does lookup, returns the object with parent locked */ 244479714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 24455590ff0dSUlrich Drepper { 24465c31b6ceSAl Viro struct filename *filename; 24475c31b6ceSAl Viro struct dentry *d; 2448391172c4SAl Viro struct qstr last; 2449391172c4SAl Viro int type; 245051689104SPaul Moore 24515c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 24525c31b6ceSAl Viro &last, &type); 245351689104SPaul Moore if (IS_ERR(filename)) 245451689104SPaul Moore return ERR_CAST(filename); 24555c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2456391172c4SAl Viro path_put(path); 24575c31b6ceSAl Viro putname(filename); 24585c31b6ceSAl Viro return ERR_PTR(-EINVAL); 245979714f72SAl Viro } 24605955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2461391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 246279714f72SAl Viro if (IS_ERR(d)) { 24635955102cSAl Viro inode_unlock(path->dentry->d_inode); 2464391172c4SAl Viro path_put(path); 246579714f72SAl Viro } 246651689104SPaul Moore putname(filename); 246779714f72SAl Viro return d; 24685590ff0dSUlrich Drepper } 24695590ff0dSUlrich Drepper 2470d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2471d1811465SAl Viro { 2472abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2473abc9f5beSAl Viro flags, path, NULL); 2474d1811465SAl Viro } 24754d359507SAl Viro EXPORT_SYMBOL(kern_path); 2476d1811465SAl Viro 247716f18200SJosef 'Jeff' Sipek /** 247816f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 247916f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 248016f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 248116f18200SJosef 'Jeff' Sipek * @name: pointer to file name 248216f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2483e0a01249SAl Viro * @path: pointer to struct path to fill 248416f18200SJosef 'Jeff' Sipek */ 248516f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 248616f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2487e0a01249SAl Viro struct path *path) 248816f18200SJosef 'Jeff' Sipek { 24899ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 24909ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2491abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2492abc9f5beSAl Viro flags , path, &root); 249316f18200SJosef 'Jeff' Sipek } 24944d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 249516f18200SJosef 'Jeff' Sipek 24963c95f0dcSAl Viro static int lookup_one_len_common(const char *name, struct dentry *base, 24973c95f0dcSAl Viro int len, struct qstr *this) 24983c95f0dcSAl Viro { 24993c95f0dcSAl Viro this->name = name; 25003c95f0dcSAl Viro this->len = len; 25013c95f0dcSAl Viro this->hash = full_name_hash(base, name, len); 25023c95f0dcSAl Viro if (!len) 25033c95f0dcSAl Viro return -EACCES; 25043c95f0dcSAl Viro 25053c95f0dcSAl Viro if (unlikely(name[0] == '.')) { 25063c95f0dcSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 25073c95f0dcSAl Viro return -EACCES; 25083c95f0dcSAl Viro } 25093c95f0dcSAl Viro 25103c95f0dcSAl Viro while (len--) { 25113c95f0dcSAl Viro unsigned int c = *(const unsigned char *)name++; 25123c95f0dcSAl Viro if (c == '/' || c == '\0') 25133c95f0dcSAl Viro return -EACCES; 25143c95f0dcSAl Viro } 25153c95f0dcSAl Viro /* 25163c95f0dcSAl Viro * See if the low-level filesystem might want 25173c95f0dcSAl Viro * to use its own hash.. 25183c95f0dcSAl Viro */ 25193c95f0dcSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 25203c95f0dcSAl Viro int err = base->d_op->d_hash(base, this); 25213c95f0dcSAl Viro if (err < 0) 25223c95f0dcSAl Viro return err; 25233c95f0dcSAl Viro } 25243c95f0dcSAl Viro 25253c95f0dcSAl Viro return inode_permission(base->d_inode, MAY_EXEC); 25263c95f0dcSAl Viro } 25273c95f0dcSAl Viro 2528eead1911SChristoph Hellwig /** 25290da0b7fdSDavid Howells * try_lookup_one_len - filesystem helper to lookup single pathname component 25300da0b7fdSDavid Howells * @name: pathname component to lookup 25310da0b7fdSDavid Howells * @base: base directory to lookup from 25320da0b7fdSDavid Howells * @len: maximum length @len should be interpreted to 25330da0b7fdSDavid Howells * 25340da0b7fdSDavid Howells * Look up a dentry by name in the dcache, returning NULL if it does not 25350da0b7fdSDavid Howells * currently exist. The function does not try to create a dentry. 25360da0b7fdSDavid Howells * 25370da0b7fdSDavid Howells * Note that this routine is purely a helper for filesystem usage and should 25380da0b7fdSDavid Howells * not be called by generic code. 25390da0b7fdSDavid Howells * 25400da0b7fdSDavid Howells * The caller must hold base->i_mutex. 25410da0b7fdSDavid Howells */ 25420da0b7fdSDavid Howells struct dentry *try_lookup_one_len(const char *name, struct dentry *base, int len) 25430da0b7fdSDavid Howells { 25440da0b7fdSDavid Howells struct qstr this; 25450da0b7fdSDavid Howells int err; 25460da0b7fdSDavid Howells 25470da0b7fdSDavid Howells WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 25480da0b7fdSDavid Howells 25490da0b7fdSDavid Howells err = lookup_one_len_common(name, base, len, &this); 25500da0b7fdSDavid Howells if (err) 25510da0b7fdSDavid Howells return ERR_PTR(err); 25520da0b7fdSDavid Howells 25530da0b7fdSDavid Howells return lookup_dcache(&this, base, 0); 25540da0b7fdSDavid Howells } 25550da0b7fdSDavid Howells EXPORT_SYMBOL(try_lookup_one_len); 25560da0b7fdSDavid Howells 25570da0b7fdSDavid Howells /** 2558a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2559eead1911SChristoph Hellwig * @name: pathname component to lookup 2560eead1911SChristoph Hellwig * @base: base directory to lookup from 2561eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2562eead1911SChristoph Hellwig * 2563a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 25649e7543e9SAl Viro * not be called by generic code. 2565bbddca8eSNeilBrown * 2566bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2567eead1911SChristoph Hellwig */ 2568057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2569057f6c01SJames Morris { 25708613a209SAl Viro struct dentry *dentry; 2571057f6c01SJames Morris struct qstr this; 2572cda309deSMiklos Szeredi int err; 2573057f6c01SJames Morris 25745955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 25752f9092e1SDavid Woodhouse 25763c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2577cda309deSMiklos Szeredi if (err) 2578cda309deSMiklos Szeredi return ERR_PTR(err); 2579cda309deSMiklos Szeredi 25808613a209SAl Viro dentry = lookup_dcache(&this, base, 0); 25818613a209SAl Viro return dentry ? dentry : __lookup_slow(&this, base, 0); 2582057f6c01SJames Morris } 25834d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2584057f6c01SJames Morris 2585bbddca8eSNeilBrown /** 2586bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2587bbddca8eSNeilBrown * @name: pathname component to lookup 2588bbddca8eSNeilBrown * @base: base directory to lookup from 2589bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2590bbddca8eSNeilBrown * 2591bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2592bbddca8eSNeilBrown * not be called by generic code. 2593bbddca8eSNeilBrown * 2594bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2595bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2596bbddca8eSNeilBrown */ 2597bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2598bbddca8eSNeilBrown struct dentry *base, int len) 2599bbddca8eSNeilBrown { 2600bbddca8eSNeilBrown struct qstr this; 2601bbddca8eSNeilBrown int err; 260220d00ee8SLinus Torvalds struct dentry *ret; 2603bbddca8eSNeilBrown 26043c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2605bbddca8eSNeilBrown if (err) 2606bbddca8eSNeilBrown return ERR_PTR(err); 2607bbddca8eSNeilBrown 260820d00ee8SLinus Torvalds ret = lookup_dcache(&this, base, 0); 260920d00ee8SLinus Torvalds if (!ret) 261020d00ee8SLinus Torvalds ret = lookup_slow(&this, base, 0); 261120d00ee8SLinus Torvalds return ret; 2612bbddca8eSNeilBrown } 2613bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2614bbddca8eSNeilBrown 26156c2d4798SAl Viro /* 26166c2d4798SAl Viro * Like lookup_one_len_unlocked(), except that it yields ERR_PTR(-ENOENT) 26176c2d4798SAl Viro * on negatives. Returns known positive or ERR_PTR(); that's what 26186c2d4798SAl Viro * most of the users want. Note that pinned negative with unlocked parent 26196c2d4798SAl Viro * _can_ become positive at any time, so callers of lookup_one_len_unlocked() 26206c2d4798SAl Viro * need to be very careful; pinned positives have ->d_inode stable, so 26216c2d4798SAl Viro * this one avoids such problems. 26226c2d4798SAl Viro */ 26236c2d4798SAl Viro struct dentry *lookup_positive_unlocked(const char *name, 26246c2d4798SAl Viro struct dentry *base, int len) 26256c2d4798SAl Viro { 26266c2d4798SAl Viro struct dentry *ret = lookup_one_len_unlocked(name, base, len); 26272fa6b1e0SAl Viro if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) { 26286c2d4798SAl Viro dput(ret); 26296c2d4798SAl Viro ret = ERR_PTR(-ENOENT); 26306c2d4798SAl Viro } 26316c2d4798SAl Viro return ret; 26326c2d4798SAl Viro } 26336c2d4798SAl Viro EXPORT_SYMBOL(lookup_positive_unlocked); 26346c2d4798SAl Viro 2635eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2636eedf265aSEric W. Biederman int path_pts(struct path *path) 2637eedf265aSEric W. Biederman { 2638eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2639eedf265aSEric W. Biederman * the input path. 2640eedf265aSEric W. Biederman */ 2641a6a7eb76SAl Viro struct dentry *parent = dget_parent(path->dentry); 2642a6a7eb76SAl Viro struct dentry *child; 2643eedf265aSEric W. Biederman struct qstr this; 2644eedf265aSEric W. Biederman 2645a6a7eb76SAl Viro if (unlikely(!path_connected(path->mnt, parent))) { 2646a6a7eb76SAl Viro dput(parent); 264763b27720SAl Viro return -ENOENT; 2648a6a7eb76SAl Viro } 264963b27720SAl Viro dput(path->dentry); 265063b27720SAl Viro path->dentry = parent; 2651eedf265aSEric W. Biederman this.name = "pts"; 2652eedf265aSEric W. Biederman this.len = 3; 2653eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2654eedf265aSEric W. Biederman if (!child) 2655eedf265aSEric W. Biederman return -ENOENT; 2656eedf265aSEric W. Biederman 2657eedf265aSEric W. Biederman path->dentry = child; 2658eedf265aSEric W. Biederman dput(parent); 2659eedf265aSEric W. Biederman follow_mount(path); 2660eedf265aSEric W. Biederman return 0; 2661eedf265aSEric W. Biederman } 2662eedf265aSEric W. Biederman #endif 2663eedf265aSEric W. Biederman 26641fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 26651fa1e7f6SAndy Whitcroft struct path *path, int *empty) 26661da177e4SLinus Torvalds { 2667abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2668abc9f5beSAl Viro flags, path, NULL); 26691da177e4SLinus Torvalds } 2670b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 26711fa1e7f6SAndy Whitcroft 2672cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 26731da177e4SLinus Torvalds { 26748e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2675da9592edSDavid Howells 26768e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 26771da177e4SLinus Torvalds return 0; 26788e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 26791da177e4SLinus Torvalds return 0; 268023adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 26811da177e4SLinus Torvalds } 2682cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 26831da177e4SLinus Torvalds 26841da177e4SLinus Torvalds /* 26851da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 26861da177e4SLinus Torvalds * whether the type of victim is right. 26871da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 26881da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 26891da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 26901da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 26911da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 26921da177e4SLinus Torvalds * a. be owner of dir, or 26931da177e4SLinus Torvalds * b. be owner of victim, or 26941da177e4SLinus Torvalds * c. have CAP_FOWNER capability 26951da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 26961da177e4SLinus Torvalds * links pointing to it. 26970bd23d09SEric W. Biederman * 7. If the victim has an unknown uid or gid we can't change the inode. 26980bd23d09SEric W. Biederman * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. 26990bd23d09SEric W. Biederman * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. 27000bd23d09SEric W. Biederman * 10. We can't remove a root or mountpoint. 27010bd23d09SEric W. Biederman * 11. We don't allow removal of NFS sillyrenamed files; it's handled by 27021da177e4SLinus Torvalds * nfs_async_unlink(). 27031da177e4SLinus Torvalds */ 2704b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 27051da177e4SLinus Torvalds { 270663afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 27071da177e4SLinus Torvalds int error; 27081da177e4SLinus Torvalds 2709b18825a7SDavid Howells if (d_is_negative(victim)) 27101da177e4SLinus Torvalds return -ENOENT; 2711b18825a7SDavid Howells BUG_ON(!inode); 27121da177e4SLinus Torvalds 27131da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 2714593d1ce8SEric W. Biederman 2715593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 2716593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 2717593d1ce8SEric W. Biederman return -EOVERFLOW; 2718593d1ce8SEric W. Biederman 27194fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 27201da177e4SLinus Torvalds 2721f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 27221da177e4SLinus Torvalds if (error) 27231da177e4SLinus Torvalds return error; 27241da177e4SLinus Torvalds if (IS_APPEND(dir)) 27251da177e4SLinus Torvalds return -EPERM; 2726b18825a7SDavid Howells 2727b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 27280bd23d09SEric W. Biederman IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) 27291da177e4SLinus Torvalds return -EPERM; 27301da177e4SLinus Torvalds if (isdir) { 273144b1d530SMiklos Szeredi if (!d_is_dir(victim)) 27321da177e4SLinus Torvalds return -ENOTDIR; 27331da177e4SLinus Torvalds if (IS_ROOT(victim)) 27341da177e4SLinus Torvalds return -EBUSY; 273544b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 27361da177e4SLinus Torvalds return -EISDIR; 27371da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27381da177e4SLinus Torvalds return -ENOENT; 27391da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 27401da177e4SLinus Torvalds return -EBUSY; 27411da177e4SLinus Torvalds return 0; 27421da177e4SLinus Torvalds } 27431da177e4SLinus Torvalds 27441da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 27451da177e4SLinus Torvalds * dir. 27461da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 27471da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 27481da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 2749036d5236SEric W. Biederman * 3. We can't do it if the fs can't represent the fsuid or fsgid. 2750036d5236SEric W. Biederman * 4. We should have write and exec permissions on dir 2751036d5236SEric W. Biederman * 5. We can't do it if dir is immutable (done in permission()) 27521da177e4SLinus Torvalds */ 2753a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 27541da177e4SLinus Torvalds { 2755036d5236SEric W. Biederman struct user_namespace *s_user_ns; 275614e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 27571da177e4SLinus Torvalds if (child->d_inode) 27581da177e4SLinus Torvalds return -EEXIST; 27591da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27601da177e4SLinus Torvalds return -ENOENT; 2761036d5236SEric W. Biederman s_user_ns = dir->i_sb->s_user_ns; 2762036d5236SEric W. Biederman if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 2763036d5236SEric W. Biederman !kgid_has_mapping(s_user_ns, current_fsgid())) 2764036d5236SEric W. Biederman return -EOVERFLOW; 2765f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 27661da177e4SLinus Torvalds } 27671da177e4SLinus Torvalds 27681da177e4SLinus Torvalds /* 27691da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 27701da177e4SLinus Torvalds */ 27711da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 27721da177e4SLinus Torvalds { 27731da177e4SLinus Torvalds struct dentry *p; 27741da177e4SLinus Torvalds 27751da177e4SLinus Torvalds if (p1 == p2) { 27765955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27771da177e4SLinus Torvalds return NULL; 27781da177e4SLinus Torvalds } 27791da177e4SLinus Torvalds 2780fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 27811da177e4SLinus Torvalds 2782e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2783e2761a11SOGAWA Hirofumi if (p) { 27845955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 27855955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 27861da177e4SLinus Torvalds return p; 27871da177e4SLinus Torvalds } 27881da177e4SLinus Torvalds 2789e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2790e2761a11SOGAWA Hirofumi if (p) { 27915955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27925955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 27931da177e4SLinus Torvalds return p; 27941da177e4SLinus Torvalds } 27951da177e4SLinus Torvalds 27965955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27975955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 27981da177e4SLinus Torvalds return NULL; 27991da177e4SLinus Torvalds } 28004d359507SAl Viro EXPORT_SYMBOL(lock_rename); 28011da177e4SLinus Torvalds 28021da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 28031da177e4SLinus Torvalds { 28045955102cSAl Viro inode_unlock(p1->d_inode); 28051da177e4SLinus Torvalds if (p1 != p2) { 28065955102cSAl Viro inode_unlock(p2->d_inode); 2807fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 28081da177e4SLinus Torvalds } 28091da177e4SLinus Torvalds } 28104d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 28111da177e4SLinus Torvalds 28124acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2813312b63fbSAl Viro bool want_excl) 28141da177e4SLinus Torvalds { 2815a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28161da177e4SLinus Torvalds if (error) 28171da177e4SLinus Torvalds return error; 28181da177e4SLinus Torvalds 2819acfa4380SAl Viro if (!dir->i_op->create) 28201da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 28211da177e4SLinus Torvalds mode &= S_IALLUGO; 28221da177e4SLinus Torvalds mode |= S_IFREG; 28231da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 28241da177e4SLinus Torvalds if (error) 28251da177e4SLinus Torvalds return error; 2826312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2827a74574aaSStephen Smalley if (!error) 2828f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28291da177e4SLinus Torvalds return error; 28301da177e4SLinus Torvalds } 28314d359507SAl Viro EXPORT_SYMBOL(vfs_create); 28321da177e4SLinus Torvalds 28338e6c848eSAl Viro int vfs_mkobj(struct dentry *dentry, umode_t mode, 28348e6c848eSAl Viro int (*f)(struct dentry *, umode_t, void *), 28358e6c848eSAl Viro void *arg) 28368e6c848eSAl Viro { 28378e6c848eSAl Viro struct inode *dir = dentry->d_parent->d_inode; 28388e6c848eSAl Viro int error = may_create(dir, dentry); 28398e6c848eSAl Viro if (error) 28408e6c848eSAl Viro return error; 28418e6c848eSAl Viro 28428e6c848eSAl Viro mode &= S_IALLUGO; 28438e6c848eSAl Viro mode |= S_IFREG; 28448e6c848eSAl Viro error = security_inode_create(dir, dentry, mode); 28458e6c848eSAl Viro if (error) 28468e6c848eSAl Viro return error; 28478e6c848eSAl Viro error = f(dentry, mode, arg); 28488e6c848eSAl Viro if (!error) 28498e6c848eSAl Viro fsnotify_create(dir, dentry); 28508e6c848eSAl Viro return error; 28518e6c848eSAl Viro } 28528e6c848eSAl Viro EXPORT_SYMBOL(vfs_mkobj); 28538e6c848eSAl Viro 2854a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 2855a2982cc9SEric W. Biederman { 2856a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 2857a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 2858a2982cc9SEric W. Biederman } 2859a2982cc9SEric W. Biederman 2860f0bb5aafSAl Viro static int may_open(const struct path *path, int acc_mode, int flag) 28611da177e4SLinus Torvalds { 28623fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 28631da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 28641da177e4SLinus Torvalds int error; 28651da177e4SLinus Torvalds 28661da177e4SLinus Torvalds if (!inode) 28671da177e4SLinus Torvalds return -ENOENT; 28681da177e4SLinus Torvalds 2869c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2870c8fe8f30SChristoph Hellwig case S_IFLNK: 28711da177e4SLinus Torvalds return -ELOOP; 2872c8fe8f30SChristoph Hellwig case S_IFDIR: 2873c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 28741da177e4SLinus Torvalds return -EISDIR; 2875c8fe8f30SChristoph Hellwig break; 2876c8fe8f30SChristoph Hellwig case S_IFBLK: 2877c8fe8f30SChristoph Hellwig case S_IFCHR: 2878a2982cc9SEric W. Biederman if (!may_open_dev(path)) 28791da177e4SLinus Torvalds return -EACCES; 2880c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2881c8fe8f30SChristoph Hellwig case S_IFIFO: 2882c8fe8f30SChristoph Hellwig case S_IFSOCK: 28831da177e4SLinus Torvalds flag &= ~O_TRUNC; 2884c8fe8f30SChristoph Hellwig break; 28854a3fd211SDave Hansen } 2886b41572e9SDave Hansen 288762fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2888b41572e9SDave Hansen if (error) 2889b41572e9SDave Hansen return error; 28906146f0d5SMimi Zohar 28911da177e4SLinus Torvalds /* 28921da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 28931da177e4SLinus Torvalds */ 28941da177e4SLinus Torvalds if (IS_APPEND(inode)) { 28958737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 28967715b521SAl Viro return -EPERM; 28971da177e4SLinus Torvalds if (flag & O_TRUNC) 28987715b521SAl Viro return -EPERM; 28991da177e4SLinus Torvalds } 29001da177e4SLinus Torvalds 29011da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 29022e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 29037715b521SAl Viro return -EPERM; 29041da177e4SLinus Torvalds 2905f3c7691eSJ. Bruce Fields return 0; 29067715b521SAl Viro } 29077715b521SAl Viro 2908e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 29097715b521SAl Viro { 2910f0bb5aafSAl Viro const struct path *path = &filp->f_path; 29117715b521SAl Viro struct inode *inode = path->dentry->d_inode; 29127715b521SAl Viro int error = get_write_access(inode); 29131da177e4SLinus Torvalds if (error) 29147715b521SAl Viro return error; 29151da177e4SLinus Torvalds /* 29161da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 29171da177e4SLinus Torvalds */ 2918d7a06983SJeff Layton error = locks_verify_locked(filp); 2919be6d3e56SKentaro Takeda if (!error) 2920ea0d3ab2STetsuo Handa error = security_path_truncate(path); 29211da177e4SLinus Torvalds if (!error) { 29227715b521SAl Viro error = do_truncate(path->dentry, 0, 2923d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2924e1181ee6SJeff Layton filp); 29251da177e4SLinus Torvalds } 29261da177e4SLinus Torvalds put_write_access(inode); 2927acd0c935SMimi Zohar return error; 29281da177e4SLinus Torvalds } 29291da177e4SLinus Torvalds 2930d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2931d57999e1SDave Hansen { 29328a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 29338a5e929dSAl Viro flag--; 2934d57999e1SDave Hansen return flag; 2935d57999e1SDave Hansen } 2936d57999e1SDave Hansen 2937d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 2938d18e9008SMiklos Szeredi { 29391328c727SSeth Forshee struct user_namespace *s_user_ns; 2940d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2941d18e9008SMiklos Szeredi if (error) 2942d18e9008SMiklos Szeredi return error; 2943d18e9008SMiklos Szeredi 29441328c727SSeth Forshee s_user_ns = dir->dentry->d_sb->s_user_ns; 29451328c727SSeth Forshee if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 29461328c727SSeth Forshee !kgid_has_mapping(s_user_ns, current_fsgid())) 29471328c727SSeth Forshee return -EOVERFLOW; 29481328c727SSeth Forshee 2949d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2950d18e9008SMiklos Szeredi if (error) 2951d18e9008SMiklos Szeredi return error; 2952d18e9008SMiklos Szeredi 2953d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2954d18e9008SMiklos Szeredi } 2955d18e9008SMiklos Szeredi 29561acf0af9SDavid Howells /* 29571acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 29581acf0af9SDavid Howells * dentry. 29591acf0af9SDavid Howells * 29601acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 29611acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 29621acf0af9SDavid Howells * 296300a07c15SAl Viro * If the file was looked up only or didn't need creating, FMODE_OPENED won't 296400a07c15SAl Viro * be set. The caller will need to perform the open themselves. @path will 296500a07c15SAl Viro * have been updated to point to the new dentry. This may be negative. 29661acf0af9SDavid Howells * 29671acf0af9SDavid Howells * Returns an error code otherwise. 29681acf0af9SDavid Howells */ 2969239eb983SAl Viro static struct dentry *atomic_open(struct nameidata *nd, struct dentry *dentry, 2970239eb983SAl Viro struct file *file, 2971015c3bbcSMiklos Szeredi const struct open_flags *op, 29723ec2eef1SAl Viro int open_flag, umode_t mode) 2973d18e9008SMiklos Szeredi { 2974d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2975d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2976d18e9008SMiklos Szeredi int error; 2977d18e9008SMiklos Szeredi 2978384f26e2SAl Viro if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ 2979d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2980d18e9008SMiklos Szeredi 2981d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2982d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2983d18e9008SMiklos Szeredi 298430d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 298530d90494SAl Viro file->f_path.mnt = nd->path.mnt; 29860fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 298744907d79SAl Viro open_to_namei_flags(open_flag), mode); 29886fbd0714SAl Viro d_lookup_done(dentry); 2989384f26e2SAl Viro if (!error) { 299064e1ac4dSAl Viro if (file->f_mode & FMODE_OPENED) { 29916fb968cdSAl Viro if (unlikely(dentry != file->f_path.dentry)) { 29926fb968cdSAl Viro dput(dentry); 29936fb968cdSAl Viro dentry = dget(file->f_path.dentry); 29946fb968cdSAl Viro } 29957be219b4SAl Viro if (file->f_mode & FMODE_CREATED) 299603da633aSAl Viro fsnotify_create(dir, dentry); 299764e1ac4dSAl Viro } else if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 2998116cc022SMiklos Szeredi error = -EIO; 2999384f26e2SAl Viro } else { 3000d18e9008SMiklos Szeredi if (file->f_path.dentry) { 3001d18e9008SMiklos Szeredi dput(dentry); 3002d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 300310c64ceaSAl Viro } 300473a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) 3005d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 3006239eb983SAl Viro if (unlikely(d_is_negative(dentry))) 3007a01e718fSAl Viro error = -ENOENT; 3008d18e9008SMiklos Szeredi } 3009d18e9008SMiklos Szeredi } 3010239eb983SAl Viro if (error) { 3011d18e9008SMiklos Szeredi dput(dentry); 3012239eb983SAl Viro dentry = ERR_PTR(error); 3013239eb983SAl Viro } 3014239eb983SAl Viro return dentry; 3015d18e9008SMiklos Szeredi } 3016d18e9008SMiklos Szeredi 301731e6b01fSNick Piggin /* 30181acf0af9SDavid Howells * Look up and maybe create and open the last component. 3019d58ffd35SMiklos Szeredi * 302000a07c15SAl Viro * Must be called with parent locked (exclusive in O_CREAT case). 3021d58ffd35SMiklos Szeredi * 302200a07c15SAl Viro * Returns 0 on success, that is, if 302300a07c15SAl Viro * the file was successfully atomically created (if necessary) and opened, or 302400a07c15SAl Viro * the file was not completely opened at this time, though lookups and 302500a07c15SAl Viro * creations were performed. 302600a07c15SAl Viro * These case are distinguished by presence of FMODE_OPENED on file->f_mode. 302700a07c15SAl Viro * In the latter case dentry returned in @path might be negative if O_CREAT 302800a07c15SAl Viro * hadn't been specified. 30291acf0af9SDavid Howells * 303000a07c15SAl Viro * An error code is returned on failure. 3031d58ffd35SMiklos Szeredi */ 3032da5ebf5aSAl Viro static struct dentry *lookup_open(struct nameidata *nd, struct file *file, 3033d58ffd35SMiklos Szeredi const struct open_flags *op, 30343ec2eef1SAl Viro bool got_write) 3035d58ffd35SMiklos Szeredi { 3036d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 303754ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 30381643b43fSAl Viro int open_flag = op->open_flag; 3039d58ffd35SMiklos Szeredi struct dentry *dentry; 30401643b43fSAl Viro int error, create_error = 0; 30411643b43fSAl Viro umode_t mode = op->mode; 30426fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3043d58ffd35SMiklos Szeredi 3044ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3045da5ebf5aSAl Viro return ERR_PTR(-ENOENT); 3046d58ffd35SMiklos Szeredi 304773a09dd9SAl Viro file->f_mode &= ~FMODE_CREATED; 30486fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 30496fbd0714SAl Viro for (;;) { 30506fbd0714SAl Viro if (!dentry) { 30516fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3052d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 3053da5ebf5aSAl Viro return dentry; 30546fbd0714SAl Viro } 30556fbd0714SAl Viro if (d_in_lookup(dentry)) 30566fbd0714SAl Viro break; 3057d58ffd35SMiklos Szeredi 30586fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 30596fbd0714SAl Viro if (likely(error > 0)) 30606fbd0714SAl Viro break; 30616fbd0714SAl Viro if (error) 30626fbd0714SAl Viro goto out_dput; 30636fbd0714SAl Viro d_invalidate(dentry); 30646fbd0714SAl Viro dput(dentry); 30656fbd0714SAl Viro dentry = NULL; 30666fbd0714SAl Viro } 30676fbd0714SAl Viro if (dentry->d_inode) { 3068d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3069da5ebf5aSAl Viro return dentry; 30706c51e513SAl Viro } 3071d18e9008SMiklos Szeredi 30721643b43fSAl Viro /* 30731643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 30741643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 30751643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 30761643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 30771643b43fSAl Viro * 30781643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 30791643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 30801643b43fSAl Viro */ 30811643b43fSAl Viro if (open_flag & O_CREAT) { 30821643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 30831643b43fSAl Viro mode &= ~current_umask(); 30841643b43fSAl Viro if (unlikely(!got_write)) { 30851643b43fSAl Viro create_error = -EROFS; 30861643b43fSAl Viro open_flag &= ~O_CREAT; 30871643b43fSAl Viro if (open_flag & (O_EXCL | O_TRUNC)) 30881643b43fSAl Viro goto no_open; 30891643b43fSAl Viro /* No side effects, safe to clear O_CREAT */ 30901643b43fSAl Viro } else { 30911643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 30921643b43fSAl Viro if (create_error) { 30931643b43fSAl Viro open_flag &= ~O_CREAT; 30941643b43fSAl Viro if (open_flag & O_EXCL) 30951643b43fSAl Viro goto no_open; 30961643b43fSAl Viro } 30971643b43fSAl Viro } 30981643b43fSAl Viro } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && 30991643b43fSAl Viro unlikely(!got_write)) { 31001643b43fSAl Viro /* 31011643b43fSAl Viro * No O_CREATE -> atomicity not a requirement -> fall 31021643b43fSAl Viro * back to lookup + open 31031643b43fSAl Viro */ 31041643b43fSAl Viro goto no_open; 3105d18e9008SMiklos Szeredi } 3106d18e9008SMiklos Szeredi 31071643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 3108239eb983SAl Viro dentry = atomic_open(nd, dentry, file, op, open_flag, mode); 3109da5ebf5aSAl Viro if (unlikely(create_error) && dentry == ERR_PTR(-ENOENT)) 3110da5ebf5aSAl Viro dentry = ERR_PTR(create_error); 3111da5ebf5aSAl Viro return dentry; 3112239eb983SAl Viro } 311354ef4872SMiklos Szeredi 31141643b43fSAl Viro no_open: 31156fbd0714SAl Viro if (d_in_lookup(dentry)) { 311612fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 311712fa5e24SAl Viro nd->flags); 31186fbd0714SAl Viro d_lookup_done(dentry); 311912fa5e24SAl Viro if (unlikely(res)) { 312012fa5e24SAl Viro if (IS_ERR(res)) { 312112fa5e24SAl Viro error = PTR_ERR(res); 312212fa5e24SAl Viro goto out_dput; 312312fa5e24SAl Viro } 312412fa5e24SAl Viro dput(dentry); 312512fa5e24SAl Viro dentry = res; 312612fa5e24SAl Viro } 312754ef4872SMiklos Szeredi } 312854ef4872SMiklos Szeredi 3129d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 31301643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 313173a09dd9SAl Viro file->f_mode |= FMODE_CREATED; 3132ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3133ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3134ce8644fcSAl Viro error = -EACCES; 3135d58ffd35SMiklos Szeredi goto out_dput; 313664894cf8SAl Viro } 3137ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 31381643b43fSAl Viro open_flag & O_EXCL); 3139d58ffd35SMiklos Szeredi if (error) 3140d58ffd35SMiklos Szeredi goto out_dput; 3141ce8644fcSAl Viro fsnotify_create(dir_inode, dentry); 3142d58ffd35SMiklos Szeredi } 31431643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 31441643b43fSAl Viro error = create_error; 3145d58ffd35SMiklos Szeredi goto out_dput; 3146d58ffd35SMiklos Szeredi } 3147da5ebf5aSAl Viro return dentry; 3148d58ffd35SMiklos Szeredi 3149d58ffd35SMiklos Szeredi out_dput: 3150d58ffd35SMiklos Szeredi dput(dentry); 3151da5ebf5aSAl Viro return ERR_PTR(error); 3152d58ffd35SMiklos Szeredi } 3153d58ffd35SMiklos Szeredi 3154c981a482SAl Viro static const char *open_last_lookups(struct nameidata *nd, 31553ec2eef1SAl Viro struct file *file, const struct open_flags *op) 3156fb1cc555SAl Viro { 3157a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3158ca344a89SAl Viro int open_flag = op->open_flag; 315964894cf8SAl Viro bool got_write = false; 3160254cf582SAl Viro unsigned seq; 3161a1eb3315SMiklos Szeredi struct inode *inode; 3162da5ebf5aSAl Viro struct dentry *dentry; 3163b0417d2cSAl Viro const char *res; 316416c2cd71SAl Viro int error; 3165fb1cc555SAl Viro 3166c3e380b0SAl Viro nd->flags |= op->intent; 3167c3e380b0SAl Viro 3168bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 316956676ec3SAl Viro if (nd->depth) 317056676ec3SAl Viro put_link(nd); 31717521f22bSAl Viro res = handle_dots(nd, nd->last_type); 31727521f22bSAl Viro if (likely(!res)) 31737521f22bSAl Viro res = ERR_PTR(complete_walk(nd)); 31747521f22bSAl Viro return res; 31751f36f774SAl Viro } 3176a2c36b45SAl Viro 3177ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3178fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3179fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3180fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 318120e34357SAl Viro dentry = lookup_fast(nd, &inode, &seq); 318220e34357SAl Viro if (IS_ERR(dentry)) 31831ccac622SAl Viro return ERR_CAST(dentry); 318420e34357SAl Viro if (likely(dentry)) 318571574865SMiklos Szeredi goto finish_lookup; 318671574865SMiklos Szeredi 31876583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3188b6183df7SMiklos Szeredi } else { 3189fe2d35ffSAl Viro /* create side of things */ 3190a3fbbde7SAl Viro /* 3191b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3192b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3193b6183df7SMiklos Szeredi * about to look up 3194a3fbbde7SAl Viro */ 31959f1fafeeSAl Viro error = complete_walk(nd); 3196c981a482SAl Viro if (unlikely(error)) 31971ccac622SAl Viro return ERR_PTR(error); 3198fe2d35ffSAl Viro 3199c9b07eabSAl Viro audit_inode(nd->name, dir, AUDIT_INODE_PARENT); 32001f36f774SAl Viro /* trailing slashes? */ 3201deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 32021ccac622SAl Viro return ERR_PTR(-EISDIR); 3203b6183df7SMiklos Szeredi } 32041f36f774SAl Viro 32059cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 320664894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 320764894cf8SAl Viro if (!error) 320864894cf8SAl Viro got_write = true; 320964894cf8SAl Viro /* 321064894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 321164894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 321264894cf8SAl Viro * dropping this one anyway. 321364894cf8SAl Viro */ 321464894cf8SAl Viro } 32159cf843e3SAl Viro if (open_flag & O_CREAT) 32165955102cSAl Viro inode_lock(dir->d_inode); 32179cf843e3SAl Viro else 32189cf843e3SAl Viro inode_lock_shared(dir->d_inode); 3219da5ebf5aSAl Viro dentry = lookup_open(nd, file, op, got_write); 32209cf843e3SAl Viro if (open_flag & O_CREAT) 32215955102cSAl Viro inode_unlock(dir->d_inode); 32229cf843e3SAl Viro else 32239cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3224fb1cc555SAl Viro 3225c981a482SAl Viro if (got_write) 322659e96e65SAl Viro mnt_drop_write(nd->path.mnt); 32276c0d46c4SAl Viro 322859e96e65SAl Viro if (IS_ERR(dentry)) 322959e96e65SAl Viro return ERR_CAST(dentry); 323059e96e65SAl Viro 3231973d4b73SAl Viro if (file->f_mode & (FMODE_OPENED | FMODE_CREATED)) { 3232e73cabffSAl Viro dput(nd->path.dentry); 3233e73cabffSAl Viro nd->path.dentry = dentry; 3234c981a482SAl Viro return NULL; 3235fb1cc555SAl Viro } 3236fb1cc555SAl Viro 323720e34357SAl Viro finish_lookup: 323856676ec3SAl Viro if (nd->depth) 323956676ec3SAl Viro put_link(nd); 32408c4efe22SAl Viro res = step_into(nd, WALK_TRAILING, dentry, inode, seq); 3241b0417d2cSAl Viro if (unlikely(res)) { 32421ccac622SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 3243b0417d2cSAl Viro return res; 32441ccac622SAl Viro } 324531d1726dSAl Viro 324631d1726dSAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 324731d1726dSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 32481ccac622SAl Viro return ERR_PTR(-EEXIST); 324931d1726dSAl Viro } 3250c981a482SAl Viro 32518f64fb1cSAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3252c981a482SAl Viro return ERR_PTR(complete_walk(nd)); 3253c981a482SAl Viro } 3254c981a482SAl Viro 3255c981a482SAl Viro /* 3256c981a482SAl Viro * Handle the last step of open() 3257c981a482SAl Viro */ 3258c981a482SAl Viro static const char *do_last(struct nameidata *nd, 3259c981a482SAl Viro struct file *file, const struct open_flags *op) 3260c981a482SAl Viro { 3261c981a482SAl Viro kuid_t dir_uid = nd->inode->i_uid; 3262c981a482SAl Viro umode_t dir_mode = nd->inode->i_mode; 3263c981a482SAl Viro int open_flag = op->open_flag; 3264c981a482SAl Viro bool do_truncate; 3265c981a482SAl Viro int acc_mode; 3266c981a482SAl Viro const char *link; 3267c981a482SAl Viro int error; 3268c981a482SAl Viro 3269c981a482SAl Viro link = open_last_lookups(nd, file, op); 3270c981a482SAl Viro if (unlikely(link)) 3271c981a482SAl Viro return link; 3272c981a482SAl Viro 3273973d4b73SAl Viro if (!(file->f_mode & FMODE_CREATED)) 327476ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 327530aba665SSalvatore Mesoraca if (open_flag & O_CREAT) { 327630aba665SSalvatore Mesoraca if (d_is_dir(nd->path.dentry)) 327759e96e65SAl Viro return ERR_PTR(-EISDIR); 3278d0cb5018SAl Viro error = may_create_in_sticky(dir_mode, dir_uid, 327930aba665SSalvatore Mesoraca d_backing_inode(nd->path.dentry)); 328030aba665SSalvatore Mesoraca if (unlikely(error)) 328159e96e65SAl Viro return ERR_PTR(error); 328230aba665SSalvatore Mesoraca } 328344b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 328459e96e65SAl Viro return ERR_PTR(-ENOTDIR); 32856c0d46c4SAl Viro 32868795e7d4SAl Viro do_truncate = false; 32878795e7d4SAl Viro acc_mode = op->acc_mode; 32885a2d3eddSAl Viro if (file->f_mode & FMODE_CREATED) { 32895a2d3eddSAl Viro /* Don't check for write permission, don't truncate */ 32905a2d3eddSAl Viro open_flag &= ~O_TRUNC; 32915a2d3eddSAl Viro acc_mode = 0; 32928795e7d4SAl Viro } else if (d_is_reg(nd->path.dentry) && open_flag & O_TRUNC) { 32930f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 32940f9d1a10SAl Viro if (error) 329559e96e65SAl Viro return ERR_PTR(error); 32968795e7d4SAl Viro do_truncate = true; 32970f9d1a10SAl Viro } 3298bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 32998795e7d4SAl Viro if (!error && !(file->f_mode & FMODE_OPENED)) 3300ae2bb293SAl Viro error = vfs_open(&nd->path, file); 33018795e7d4SAl Viro if (!error) 33026035a27bSAl Viro error = ima_file_check(file, op->acc_mode); 33038795e7d4SAl Viro if (!error && do_truncate) 33042675a4ebSAl Viro error = handle_truncate(file); 3305c80567c8SAl Viro if (unlikely(error > 0)) { 3306c80567c8SAl Viro WARN_ON(1); 3307c80567c8SAl Viro error = -EINVAL; 3308c80567c8SAl Viro } 33098795e7d4SAl Viro if (do_truncate) 33100f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 33111ccac622SAl Viro return ERR_PTR(error); 3312fb1cc555SAl Viro } 3313fb1cc555SAl Viro 3314af7bd4dcSAmir Goldstein struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode, int open_flag) 3315af7bd4dcSAmir Goldstein { 3316af7bd4dcSAmir Goldstein struct dentry *child = NULL; 3317af7bd4dcSAmir Goldstein struct inode *dir = dentry->d_inode; 3318af7bd4dcSAmir Goldstein struct inode *inode; 3319af7bd4dcSAmir Goldstein int error; 3320af7bd4dcSAmir Goldstein 3321af7bd4dcSAmir Goldstein /* we want directory to be writable */ 3322af7bd4dcSAmir Goldstein error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 3323af7bd4dcSAmir Goldstein if (error) 3324af7bd4dcSAmir Goldstein goto out_err; 3325af7bd4dcSAmir Goldstein error = -EOPNOTSUPP; 3326af7bd4dcSAmir Goldstein if (!dir->i_op->tmpfile) 3327af7bd4dcSAmir Goldstein goto out_err; 3328af7bd4dcSAmir Goldstein error = -ENOMEM; 3329cdf01226SDavid Howells child = d_alloc(dentry, &slash_name); 3330af7bd4dcSAmir Goldstein if (unlikely(!child)) 3331af7bd4dcSAmir Goldstein goto out_err; 3332af7bd4dcSAmir Goldstein error = dir->i_op->tmpfile(dir, child, mode); 3333af7bd4dcSAmir Goldstein if (error) 3334af7bd4dcSAmir Goldstein goto out_err; 3335af7bd4dcSAmir Goldstein error = -ENOENT; 3336af7bd4dcSAmir Goldstein inode = child->d_inode; 3337af7bd4dcSAmir Goldstein if (unlikely(!inode)) 3338af7bd4dcSAmir Goldstein goto out_err; 3339af7bd4dcSAmir Goldstein if (!(open_flag & O_EXCL)) { 3340af7bd4dcSAmir Goldstein spin_lock(&inode->i_lock); 3341af7bd4dcSAmir Goldstein inode->i_state |= I_LINKABLE; 3342af7bd4dcSAmir Goldstein spin_unlock(&inode->i_lock); 3343af7bd4dcSAmir Goldstein } 3344fdb2410fSMimi Zohar ima_post_create_tmpfile(inode); 3345af7bd4dcSAmir Goldstein return child; 3346af7bd4dcSAmir Goldstein 3347af7bd4dcSAmir Goldstein out_err: 3348af7bd4dcSAmir Goldstein dput(child); 3349af7bd4dcSAmir Goldstein return ERR_PTR(error); 3350af7bd4dcSAmir Goldstein } 3351af7bd4dcSAmir Goldstein EXPORT_SYMBOL(vfs_tmpfile); 3352af7bd4dcSAmir Goldstein 3353c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 335460545d0dSAl Viro const struct open_flags *op, 33553ec2eef1SAl Viro struct file *file) 335660545d0dSAl Viro { 3357625b6d10SAl Viro struct dentry *child; 3358625b6d10SAl Viro struct path path; 3359c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 336060545d0dSAl Viro if (unlikely(error)) 336160545d0dSAl Viro return error; 3362625b6d10SAl Viro error = mnt_want_write(path.mnt); 336360545d0dSAl Viro if (unlikely(error)) 336460545d0dSAl Viro goto out; 3365af7bd4dcSAmir Goldstein child = vfs_tmpfile(path.dentry, op->mode, op->open_flag); 3366af7bd4dcSAmir Goldstein error = PTR_ERR(child); 3367684e73beSHirofumi Nakagawa if (IS_ERR(child)) 336860545d0dSAl Viro goto out2; 3369625b6d10SAl Viro dput(path.dentry); 3370625b6d10SAl Viro path.dentry = child; 3371c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 337269a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 337362fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 337460545d0dSAl Viro if (error) 337560545d0dSAl Viro goto out2; 3376625b6d10SAl Viro file->f_path.mnt = path.mnt; 3377be12af3eSAl Viro error = finish_open(file, child, NULL); 337860545d0dSAl Viro out2: 3379625b6d10SAl Viro mnt_drop_write(path.mnt); 338060545d0dSAl Viro out: 3381625b6d10SAl Viro path_put(&path); 338260545d0dSAl Viro return error; 338360545d0dSAl Viro } 338460545d0dSAl Viro 33856ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 33866ac08709SAl Viro { 33876ac08709SAl Viro struct path path; 33886ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 33896ac08709SAl Viro if (!error) { 33906ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 3391ae2bb293SAl Viro error = vfs_open(&path, file); 33926ac08709SAl Viro path_put(&path); 33936ac08709SAl Viro } 33946ac08709SAl Viro return error; 33956ac08709SAl Viro } 33966ac08709SAl Viro 3397c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3398c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 33991da177e4SLinus Torvalds { 340030d90494SAl Viro struct file *file; 340113aab428SAl Viro int error; 340231e6b01fSNick Piggin 3403ea73ea72SAl Viro file = alloc_empty_file(op->open_flag, current_cred()); 34041afc99beSAl Viro if (IS_ERR(file)) 34051afc99beSAl Viro return file; 340631e6b01fSNick Piggin 3407bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 34083ec2eef1SAl Viro error = do_tmpfile(nd, flags, op, file); 34095f336e72SAl Viro } else if (unlikely(file->f_flags & O_PATH)) { 34106ac08709SAl Viro error = do_o_path(nd, flags, file); 34115f336e72SAl Viro } else { 34125f336e72SAl Viro const char *s = path_init(nd, flags); 34133bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 34141ccac622SAl Viro (s = do_last(nd, file, op)) != NULL) 34151ccac622SAl Viro ; 3416deb106c6SAl Viro terminate_walk(nd); 34175f336e72SAl Viro } 34187c1c01ecSAl Viro if (likely(!error)) { 3419aad888f8SAl Viro if (likely(file->f_mode & FMODE_OPENED)) 34207c1c01ecSAl Viro return file; 34217c1c01ecSAl Viro WARN_ON(1); 34227c1c01ecSAl Viro error = -EINVAL; 3423015c3bbcSMiklos Szeredi } 34247c1c01ecSAl Viro fput(file); 34252675a4ebSAl Viro if (error == -EOPENSTALE) { 34262675a4ebSAl Viro if (flags & LOOKUP_RCU) 34272675a4ebSAl Viro error = -ECHILD; 34282675a4ebSAl Viro else 34292675a4ebSAl Viro error = -ESTALE; 34302675a4ebSAl Viro } 34317c1c01ecSAl Viro return ERR_PTR(error); 3432de459215SKirill Korotaev } 34331da177e4SLinus Torvalds 3434669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3435f9652e10SAl Viro const struct open_flags *op) 343613aab428SAl Viro { 34379883d185SAl Viro struct nameidata nd; 3438f9652e10SAl Viro int flags = op->lookup_flags; 343913aab428SAl Viro struct file *filp; 344013aab428SAl Viro 34419883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3442c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 344313aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3444c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 344513aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3446c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 34479883d185SAl Viro restore_nameidata(); 344813aab428SAl Viro return filp; 344913aab428SAl Viro } 345013aab428SAl Viro 345173d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3452f9652e10SAl Viro const char *name, const struct open_flags *op) 345373d049a4SAl Viro { 34549883d185SAl Viro struct nameidata nd; 345573d049a4SAl Viro struct file *file; 345651689104SPaul Moore struct filename *filename; 3457f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 345873d049a4SAl Viro 345973d049a4SAl Viro nd.root.mnt = mnt; 346073d049a4SAl Viro nd.root.dentry = dentry; 346173d049a4SAl Viro 3462b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 346373d049a4SAl Viro return ERR_PTR(-ELOOP); 346473d049a4SAl Viro 346551689104SPaul Moore filename = getname_kernel(name); 3466a1c83681SViresh Kumar if (IS_ERR(filename)) 346751689104SPaul Moore return ERR_CAST(filename); 346851689104SPaul Moore 34699883d185SAl Viro set_nameidata(&nd, -1, filename); 3470c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 347173d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3472c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 347373d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3474c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 34759883d185SAl Viro restore_nameidata(); 347651689104SPaul Moore putname(filename); 347773d049a4SAl Viro return file; 347873d049a4SAl Viro } 347973d049a4SAl Viro 3480fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 34811ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 34821da177e4SLinus Torvalds { 3483c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3484391172c4SAl Viro struct qstr last; 3485391172c4SAl Viro int type; 3486c30dabfeSJan Kara int err2; 34871ac12b4bSJeff Layton int error; 34881ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 34891ac12b4bSJeff Layton 34901ac12b4bSJeff Layton /* 34911ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 34921ac12b4bSJeff Layton * other flags passed in are ignored! 34931ac12b4bSJeff Layton */ 34941ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 34951ac12b4bSJeff Layton 34965c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 34975c31b6ceSAl Viro if (IS_ERR(name)) 34985c31b6ceSAl Viro return ERR_CAST(name); 34991da177e4SLinus Torvalds 3500c663e5d8SChristoph Hellwig /* 3501c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3502c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3503c663e5d8SChristoph Hellwig */ 35045c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3505ed75e95dSAl Viro goto out; 3506c663e5d8SChristoph Hellwig 3507c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3508391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3509c663e5d8SChristoph Hellwig /* 3510c663e5d8SChristoph Hellwig * Do the final lookup. 3511c663e5d8SChristoph Hellwig */ 3512391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 35135955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3514391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 35151da177e4SLinus Torvalds if (IS_ERR(dentry)) 3516a8104a9fSAl Viro goto unlock; 3517c663e5d8SChristoph Hellwig 3518a8104a9fSAl Viro error = -EEXIST; 3519b18825a7SDavid Howells if (d_is_positive(dentry)) 3520a8104a9fSAl Viro goto fail; 3521b18825a7SDavid Howells 3522c663e5d8SChristoph Hellwig /* 3523c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3524c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3525c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3526c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3527c663e5d8SChristoph Hellwig */ 3528391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3529a8104a9fSAl Viro error = -ENOENT; 3530ed75e95dSAl Viro goto fail; 3531e9baf6e5SAl Viro } 3532c30dabfeSJan Kara if (unlikely(err2)) { 3533c30dabfeSJan Kara error = err2; 3534a8104a9fSAl Viro goto fail; 3535c30dabfeSJan Kara } 3536181c37b6SAl Viro putname(name); 3537e9baf6e5SAl Viro return dentry; 35381da177e4SLinus Torvalds fail: 3539a8104a9fSAl Viro dput(dentry); 3540a8104a9fSAl Viro dentry = ERR_PTR(error); 3541a8104a9fSAl Viro unlock: 35425955102cSAl Viro inode_unlock(path->dentry->d_inode); 3543c30dabfeSJan Kara if (!err2) 3544391172c4SAl Viro mnt_drop_write(path->mnt); 3545ed75e95dSAl Viro out: 3546391172c4SAl Viro path_put(path); 3547181c37b6SAl Viro putname(name); 3548ed75e95dSAl Viro return dentry; 3549dae6ad8fSAl Viro } 3550fa14a0b8SAl Viro 3551fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3552fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3553fa14a0b8SAl Viro { 3554181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3555181c37b6SAl Viro path, lookup_flags); 3556fa14a0b8SAl Viro } 3557dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3558dae6ad8fSAl Viro 3559921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3560921a1650SAl Viro { 3561921a1650SAl Viro dput(dentry); 35625955102cSAl Viro inode_unlock(path->dentry->d_inode); 3563a8104a9fSAl Viro mnt_drop_write(path->mnt); 3564921a1650SAl Viro path_put(path); 3565921a1650SAl Viro } 3566921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3567921a1650SAl Viro 3568520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 35691ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3570dae6ad8fSAl Viro { 3571181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3572dae6ad8fSAl Viro } 3573dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3574dae6ad8fSAl Viro 35751a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 35761da177e4SLinus Torvalds { 3577a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35781da177e4SLinus Torvalds 35791da177e4SLinus Torvalds if (error) 35801da177e4SLinus Torvalds return error; 35811da177e4SLinus Torvalds 358294f82008SChristian Brauner if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 35831da177e4SLinus Torvalds return -EPERM; 35841da177e4SLinus Torvalds 3585acfa4380SAl Viro if (!dir->i_op->mknod) 35861da177e4SLinus Torvalds return -EPERM; 35871da177e4SLinus Torvalds 358808ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 358908ce5f16SSerge E. Hallyn if (error) 359008ce5f16SSerge E. Hallyn return error; 359108ce5f16SSerge E. Hallyn 35921da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 35931da177e4SLinus Torvalds if (error) 35941da177e4SLinus Torvalds return error; 35951da177e4SLinus Torvalds 35961da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3597a74574aaSStephen Smalley if (!error) 3598f38aa942SAmy Griffis fsnotify_create(dir, dentry); 35991da177e4SLinus Torvalds return error; 36001da177e4SLinus Torvalds } 36014d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 36021da177e4SLinus Torvalds 3603f69aac00SAl Viro static int may_mknod(umode_t mode) 3604463c3197SDave Hansen { 3605463c3197SDave Hansen switch (mode & S_IFMT) { 3606463c3197SDave Hansen case S_IFREG: 3607463c3197SDave Hansen case S_IFCHR: 3608463c3197SDave Hansen case S_IFBLK: 3609463c3197SDave Hansen case S_IFIFO: 3610463c3197SDave Hansen case S_IFSOCK: 3611463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3612463c3197SDave Hansen return 0; 3613463c3197SDave Hansen case S_IFDIR: 3614463c3197SDave Hansen return -EPERM; 3615463c3197SDave Hansen default: 3616463c3197SDave Hansen return -EINVAL; 3617463c3197SDave Hansen } 3618463c3197SDave Hansen } 3619463c3197SDave Hansen 362087c4e192SDominik Brodowski long do_mknodat(int dfd, const char __user *filename, umode_t mode, 362187c4e192SDominik Brodowski unsigned int dev) 36221da177e4SLinus Torvalds { 36231da177e4SLinus Torvalds struct dentry *dentry; 3624dae6ad8fSAl Viro struct path path; 3625dae6ad8fSAl Viro int error; 3626972567f1SJeff Layton unsigned int lookup_flags = 0; 36271da177e4SLinus Torvalds 36288e4bfca1SAl Viro error = may_mknod(mode); 36298e4bfca1SAl Viro if (error) 36308e4bfca1SAl Viro return error; 3631972567f1SJeff Layton retry: 3632972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3633dae6ad8fSAl Viro if (IS_ERR(dentry)) 3634dae6ad8fSAl Viro return PTR_ERR(dentry); 36352ad94ae6SAl Viro 3636dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3637ce3b0f8dSAl Viro mode &= ~current_umask(); 3638dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3639be6d3e56SKentaro Takeda if (error) 3640a8104a9fSAl Viro goto out; 36411da177e4SLinus Torvalds switch (mode & S_IFMT) { 36421da177e4SLinus Torvalds case 0: case S_IFREG: 3643312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 364405d1a717SMimi Zohar if (!error) 364505d1a717SMimi Zohar ima_post_path_mknod(dentry); 36461da177e4SLinus Torvalds break; 36471da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3648dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 36491da177e4SLinus Torvalds new_decode_dev(dev)); 36501da177e4SLinus Torvalds break; 36511da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3652dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 36531da177e4SLinus Torvalds break; 36541da177e4SLinus Torvalds } 3655a8104a9fSAl Viro out: 3656921a1650SAl Viro done_path_create(&path, dentry); 3657972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3658972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3659972567f1SJeff Layton goto retry; 3660972567f1SJeff Layton } 36611da177e4SLinus Torvalds return error; 36621da177e4SLinus Torvalds } 36631da177e4SLinus Torvalds 366487c4e192SDominik Brodowski SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 366587c4e192SDominik Brodowski unsigned int, dev) 366687c4e192SDominik Brodowski { 366787c4e192SDominik Brodowski return do_mknodat(dfd, filename, mode, dev); 366887c4e192SDominik Brodowski } 366987c4e192SDominik Brodowski 36708208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 36715590ff0dSUlrich Drepper { 367287c4e192SDominik Brodowski return do_mknodat(AT_FDCWD, filename, mode, dev); 36735590ff0dSUlrich Drepper } 36745590ff0dSUlrich Drepper 367518bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 36761da177e4SLinus Torvalds { 3677a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36788de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 36791da177e4SLinus Torvalds 36801da177e4SLinus Torvalds if (error) 36811da177e4SLinus Torvalds return error; 36821da177e4SLinus Torvalds 3683acfa4380SAl Viro if (!dir->i_op->mkdir) 36841da177e4SLinus Torvalds return -EPERM; 36851da177e4SLinus Torvalds 36861da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 36871da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 36881da177e4SLinus Torvalds if (error) 36891da177e4SLinus Torvalds return error; 36901da177e4SLinus Torvalds 36918de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 36928de52778SAl Viro return -EMLINK; 36938de52778SAl Viro 36941da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3695a74574aaSStephen Smalley if (!error) 3696f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 36971da177e4SLinus Torvalds return error; 36981da177e4SLinus Torvalds } 36994d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 37001da177e4SLinus Torvalds 37010101db7aSDominik Brodowski long do_mkdirat(int dfd, const char __user *pathname, umode_t mode) 37021da177e4SLinus Torvalds { 37036902d925SDave Hansen struct dentry *dentry; 3704dae6ad8fSAl Viro struct path path; 3705dae6ad8fSAl Viro int error; 3706b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 37071da177e4SLinus Torvalds 3708b76d8b82SJeff Layton retry: 3709b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 37106902d925SDave Hansen if (IS_ERR(dentry)) 3711dae6ad8fSAl Viro return PTR_ERR(dentry); 37126902d925SDave Hansen 3713dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3714ce3b0f8dSAl Viro mode &= ~current_umask(); 3715dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3716a8104a9fSAl Viro if (!error) 3717dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3718921a1650SAl Viro done_path_create(&path, dentry); 3719b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3720b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3721b76d8b82SJeff Layton goto retry; 3722b76d8b82SJeff Layton } 37231da177e4SLinus Torvalds return error; 37241da177e4SLinus Torvalds } 37251da177e4SLinus Torvalds 37260101db7aSDominik Brodowski SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 37270101db7aSDominik Brodowski { 37280101db7aSDominik Brodowski return do_mkdirat(dfd, pathname, mode); 37290101db7aSDominik Brodowski } 37300101db7aSDominik Brodowski 3731a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 37325590ff0dSUlrich Drepper { 37330101db7aSDominik Brodowski return do_mkdirat(AT_FDCWD, pathname, mode); 37345590ff0dSUlrich Drepper } 37355590ff0dSUlrich Drepper 37361da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 37371da177e4SLinus Torvalds { 37381da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 37391da177e4SLinus Torvalds 37401da177e4SLinus Torvalds if (error) 37411da177e4SLinus Torvalds return error; 37421da177e4SLinus Torvalds 3743acfa4380SAl Viro if (!dir->i_op->rmdir) 37441da177e4SLinus Torvalds return -EPERM; 37451da177e4SLinus Torvalds 37461d2ef590SAl Viro dget(dentry); 37475955102cSAl Viro inode_lock(dentry->d_inode); 3748912dbc15SSage Weil 37491da177e4SLinus Torvalds error = -EBUSY; 37507af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3751912dbc15SSage Weil goto out; 3752912dbc15SSage Weil 37531da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3754912dbc15SSage Weil if (error) 3755912dbc15SSage Weil goto out; 3756912dbc15SSage Weil 37571da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3758912dbc15SSage Weil if (error) 3759912dbc15SSage Weil goto out; 3760912dbc15SSage Weil 37618767712fSAl Viro shrink_dcache_parent(dentry); 37621da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3763d83c49f3SAl Viro dont_mount(dentry); 37648ed936b5SEric W. Biederman detach_mounts(dentry); 3765116b9731SAmir Goldstein fsnotify_rmdir(dir, dentry); 37661da177e4SLinus Torvalds 3767912dbc15SSage Weil out: 37685955102cSAl Viro inode_unlock(dentry->d_inode); 37691d2ef590SAl Viro dput(dentry); 3770912dbc15SSage Weil if (!error) 3771912dbc15SSage Weil d_delete(dentry); 37721da177e4SLinus Torvalds return error; 37731da177e4SLinus Torvalds } 37744d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 37751da177e4SLinus Torvalds 3776f459dffaSDominik Brodowski long do_rmdir(int dfd, const char __user *pathname) 37771da177e4SLinus Torvalds { 37781da177e4SLinus Torvalds int error = 0; 377991a27b2aSJeff Layton struct filename *name; 37801da177e4SLinus Torvalds struct dentry *dentry; 3781f5beed75SAl Viro struct path path; 3782f5beed75SAl Viro struct qstr last; 3783f5beed75SAl Viro int type; 3784c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3785c6ee9206SJeff Layton retry: 3786c1d4dd27SAl Viro name = filename_parentat(dfd, getname(pathname), lookup_flags, 3787c1d4dd27SAl Viro &path, &last, &type); 378891a27b2aSJeff Layton if (IS_ERR(name)) 378991a27b2aSJeff Layton return PTR_ERR(name); 37901da177e4SLinus Torvalds 3791f5beed75SAl Viro switch (type) { 37921da177e4SLinus Torvalds case LAST_DOTDOT: 37931da177e4SLinus Torvalds error = -ENOTEMPTY; 37941da177e4SLinus Torvalds goto exit1; 37951da177e4SLinus Torvalds case LAST_DOT: 37961da177e4SLinus Torvalds error = -EINVAL; 37971da177e4SLinus Torvalds goto exit1; 37981da177e4SLinus Torvalds case LAST_ROOT: 37991da177e4SLinus Torvalds error = -EBUSY; 38001da177e4SLinus Torvalds goto exit1; 38011da177e4SLinus Torvalds } 38020612d9fbSOGAWA Hirofumi 3803f5beed75SAl Viro error = mnt_want_write(path.mnt); 3804c30dabfeSJan Kara if (error) 3805c30dabfeSJan Kara goto exit1; 38060612d9fbSOGAWA Hirofumi 38075955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3808f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38091da177e4SLinus Torvalds error = PTR_ERR(dentry); 38106902d925SDave Hansen if (IS_ERR(dentry)) 38116902d925SDave Hansen goto exit2; 3812e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3813e6bc45d6STheodore Ts'o error = -ENOENT; 3814e6bc45d6STheodore Ts'o goto exit3; 3815e6bc45d6STheodore Ts'o } 3816f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3817be6d3e56SKentaro Takeda if (error) 3818c30dabfeSJan Kara goto exit3; 3819f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 38200622753bSDave Hansen exit3: 38211da177e4SLinus Torvalds dput(dentry); 38226902d925SDave Hansen exit2: 38235955102cSAl Viro inode_unlock(path.dentry->d_inode); 3824f5beed75SAl Viro mnt_drop_write(path.mnt); 38251da177e4SLinus Torvalds exit1: 3826f5beed75SAl Viro path_put(&path); 38271da177e4SLinus Torvalds putname(name); 3828c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3829c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3830c6ee9206SJeff Layton goto retry; 3831c6ee9206SJeff Layton } 38321da177e4SLinus Torvalds return error; 38331da177e4SLinus Torvalds } 38341da177e4SLinus Torvalds 38353cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 38365590ff0dSUlrich Drepper { 38375590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 38385590ff0dSUlrich Drepper } 38395590ff0dSUlrich Drepper 3840b21996e3SJ. Bruce Fields /** 3841b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3842b21996e3SJ. Bruce Fields * @dir: parent directory 3843b21996e3SJ. Bruce Fields * @dentry: victim 3844b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3845b21996e3SJ. Bruce Fields * 3846b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3847b21996e3SJ. Bruce Fields * 3848b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3849b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3850b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3851b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3852b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3853b21996e3SJ. Bruce Fields * 3854b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3855b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3856b21996e3SJ. Bruce Fields * to be NFS exported. 3857b21996e3SJ. Bruce Fields */ 3858b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 38591da177e4SLinus Torvalds { 38609accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 38611da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 38621da177e4SLinus Torvalds 38631da177e4SLinus Torvalds if (error) 38641da177e4SLinus Torvalds return error; 38651da177e4SLinus Torvalds 3866acfa4380SAl Viro if (!dir->i_op->unlink) 38671da177e4SLinus Torvalds return -EPERM; 38681da177e4SLinus Torvalds 38695955102cSAl Viro inode_lock(target); 38708ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 38711da177e4SLinus Torvalds error = -EBUSY; 38721da177e4SLinus Torvalds else { 38731da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3874bec1052eSAl Viro if (!error) { 38755a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 38765a14696cSJ. Bruce Fields if (error) 3877b21996e3SJ. Bruce Fields goto out; 38781da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 38798ed936b5SEric W. Biederman if (!error) { 3880d83c49f3SAl Viro dont_mount(dentry); 38818ed936b5SEric W. Biederman detach_mounts(dentry); 3882116b9731SAmir Goldstein fsnotify_unlink(dir, dentry); 38838ed936b5SEric W. Biederman } 3884bec1052eSAl Viro } 38851da177e4SLinus Torvalds } 3886b21996e3SJ. Bruce Fields out: 38875955102cSAl Viro inode_unlock(target); 38881da177e4SLinus Torvalds 38891da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 38901da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 38919accbb97SJ. Bruce Fields fsnotify_link_count(target); 38921da177e4SLinus Torvalds d_delete(dentry); 38931da177e4SLinus Torvalds } 38940eeca283SRobert Love 38951da177e4SLinus Torvalds return error; 38961da177e4SLinus Torvalds } 38974d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 38981da177e4SLinus Torvalds 38991da177e4SLinus Torvalds /* 39001da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 39011b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 39021da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 39031da177e4SLinus Torvalds * while waiting on the I/O. 39041da177e4SLinus Torvalds */ 3905da2f1362SChristoph Hellwig long do_unlinkat(int dfd, struct filename *name) 39061da177e4SLinus Torvalds { 39072ad94ae6SAl Viro int error; 39081da177e4SLinus Torvalds struct dentry *dentry; 3909f5beed75SAl Viro struct path path; 3910f5beed75SAl Viro struct qstr last; 3911f5beed75SAl Viro int type; 39121da177e4SLinus Torvalds struct inode *inode = NULL; 3913b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 39145d18f813SJeff Layton unsigned int lookup_flags = 0; 39155d18f813SJeff Layton retry: 3916da2f1362SChristoph Hellwig name = filename_parentat(dfd, name, lookup_flags, &path, &last, &type); 391791a27b2aSJeff Layton if (IS_ERR(name)) 391891a27b2aSJeff Layton return PTR_ERR(name); 39192ad94ae6SAl Viro 39201da177e4SLinus Torvalds error = -EISDIR; 3921f5beed75SAl Viro if (type != LAST_NORM) 39221da177e4SLinus Torvalds goto exit1; 39230612d9fbSOGAWA Hirofumi 3924f5beed75SAl Viro error = mnt_want_write(path.mnt); 3925c30dabfeSJan Kara if (error) 3926c30dabfeSJan Kara goto exit1; 3927b21996e3SJ. Bruce Fields retry_deleg: 39285955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3929f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 39301da177e4SLinus Torvalds error = PTR_ERR(dentry); 39311da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 39321da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3933f5beed75SAl Viro if (last.name[last.len]) 393450338b88STörök Edwin goto slashes; 39351da177e4SLinus Torvalds inode = dentry->d_inode; 3936b18825a7SDavid Howells if (d_is_negative(dentry)) 3937e6bc45d6STheodore Ts'o goto slashes; 39387de9c6eeSAl Viro ihold(inode); 3939f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3940be6d3e56SKentaro Takeda if (error) 3941c30dabfeSJan Kara goto exit2; 3942f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 39431da177e4SLinus Torvalds exit2: 39441da177e4SLinus Torvalds dput(dentry); 39451da177e4SLinus Torvalds } 39465955102cSAl Viro inode_unlock(path.dentry->d_inode); 39471da177e4SLinus Torvalds if (inode) 39481da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3949b21996e3SJ. Bruce Fields inode = NULL; 3950b21996e3SJ. Bruce Fields if (delegated_inode) { 39515a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3952b21996e3SJ. Bruce Fields if (!error) 3953b21996e3SJ. Bruce Fields goto retry_deleg; 3954b21996e3SJ. Bruce Fields } 3955f5beed75SAl Viro mnt_drop_write(path.mnt); 39561da177e4SLinus Torvalds exit1: 3957f5beed75SAl Viro path_put(&path); 39585d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 39595d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 39605d18f813SJeff Layton inode = NULL; 39615d18f813SJeff Layton goto retry; 39625d18f813SJeff Layton } 3963da2f1362SChristoph Hellwig putname(name); 39641da177e4SLinus Torvalds return error; 39651da177e4SLinus Torvalds 39661da177e4SLinus Torvalds slashes: 3967b18825a7SDavid Howells if (d_is_negative(dentry)) 3968b18825a7SDavid Howells error = -ENOENT; 396944b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3970b18825a7SDavid Howells error = -EISDIR; 3971b18825a7SDavid Howells else 3972b18825a7SDavid Howells error = -ENOTDIR; 39731da177e4SLinus Torvalds goto exit2; 39741da177e4SLinus Torvalds } 39751da177e4SLinus Torvalds 39762e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 39775590ff0dSUlrich Drepper { 39785590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 39795590ff0dSUlrich Drepper return -EINVAL; 39805590ff0dSUlrich Drepper 39815590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 39825590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 39835590ff0dSUlrich Drepper 3984da2f1362SChristoph Hellwig return do_unlinkat(dfd, getname(pathname)); 39855590ff0dSUlrich Drepper } 39865590ff0dSUlrich Drepper 39873480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 39885590ff0dSUlrich Drepper { 3989da2f1362SChristoph Hellwig return do_unlinkat(AT_FDCWD, getname(pathname)); 39905590ff0dSUlrich Drepper } 39915590ff0dSUlrich Drepper 3992db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 39931da177e4SLinus Torvalds { 3994a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 39951da177e4SLinus Torvalds 39961da177e4SLinus Torvalds if (error) 39971da177e4SLinus Torvalds return error; 39981da177e4SLinus Torvalds 3999acfa4380SAl Viro if (!dir->i_op->symlink) 40001da177e4SLinus Torvalds return -EPERM; 40011da177e4SLinus Torvalds 40021da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 40031da177e4SLinus Torvalds if (error) 40041da177e4SLinus Torvalds return error; 40051da177e4SLinus Torvalds 40061da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 4007a74574aaSStephen Smalley if (!error) 4008f38aa942SAmy Griffis fsnotify_create(dir, dentry); 40091da177e4SLinus Torvalds return error; 40101da177e4SLinus Torvalds } 40114d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 40121da177e4SLinus Torvalds 4013b724e846SDominik Brodowski long do_symlinkat(const char __user *oldname, int newdfd, 4014b724e846SDominik Brodowski const char __user *newname) 40151da177e4SLinus Torvalds { 40162ad94ae6SAl Viro int error; 401791a27b2aSJeff Layton struct filename *from; 40186902d925SDave Hansen struct dentry *dentry; 4019dae6ad8fSAl Viro struct path path; 4020f46d3567SJeff Layton unsigned int lookup_flags = 0; 40211da177e4SLinus Torvalds 40221da177e4SLinus Torvalds from = getname(oldname); 40231da177e4SLinus Torvalds if (IS_ERR(from)) 40241da177e4SLinus Torvalds return PTR_ERR(from); 4025f46d3567SJeff Layton retry: 4026f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 40271da177e4SLinus Torvalds error = PTR_ERR(dentry); 40286902d925SDave Hansen if (IS_ERR(dentry)) 4029dae6ad8fSAl Viro goto out_putname; 40306902d925SDave Hansen 403191a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4032a8104a9fSAl Viro if (!error) 403391a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4034921a1650SAl Viro done_path_create(&path, dentry); 4035f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4036f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4037f46d3567SJeff Layton goto retry; 4038f46d3567SJeff Layton } 40396902d925SDave Hansen out_putname: 40401da177e4SLinus Torvalds putname(from); 40411da177e4SLinus Torvalds return error; 40421da177e4SLinus Torvalds } 40431da177e4SLinus Torvalds 4044b724e846SDominik Brodowski SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 4045b724e846SDominik Brodowski int, newdfd, const char __user *, newname) 4046b724e846SDominik Brodowski { 4047b724e846SDominik Brodowski return do_symlinkat(oldname, newdfd, newname); 4048b724e846SDominik Brodowski } 4049b724e846SDominik Brodowski 40503480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 40515590ff0dSUlrich Drepper { 4052b724e846SDominik Brodowski return do_symlinkat(oldname, AT_FDCWD, newname); 40535590ff0dSUlrich Drepper } 40545590ff0dSUlrich Drepper 4055146a8595SJ. Bruce Fields /** 4056146a8595SJ. Bruce Fields * vfs_link - create a new link 4057146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4058146a8595SJ. Bruce Fields * @dir: new parent 4059146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4060146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4061146a8595SJ. Bruce Fields * 4062146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4063146a8595SJ. Bruce Fields * 4064146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4065146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4066146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4067146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4068146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4069146a8595SJ. Bruce Fields * 4070146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4071146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4072146a8595SJ. Bruce Fields * to be NFS exported. 4073146a8595SJ. Bruce Fields */ 4074146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 40751da177e4SLinus Torvalds { 40761da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 40778de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 40781da177e4SLinus Torvalds int error; 40791da177e4SLinus Torvalds 40801da177e4SLinus Torvalds if (!inode) 40811da177e4SLinus Torvalds return -ENOENT; 40821da177e4SLinus Torvalds 4083a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 40841da177e4SLinus Torvalds if (error) 40851da177e4SLinus Torvalds return error; 40861da177e4SLinus Torvalds 40871da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 40881da177e4SLinus Torvalds return -EXDEV; 40891da177e4SLinus Torvalds 40901da177e4SLinus Torvalds /* 40911da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 40921da177e4SLinus Torvalds */ 40931da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 40941da177e4SLinus Torvalds return -EPERM; 40950bd23d09SEric W. Biederman /* 40960bd23d09SEric W. Biederman * Updating the link count will likely cause i_uid and i_gid to 40970bd23d09SEric W. Biederman * be writen back improperly if their true value is unknown to 40980bd23d09SEric W. Biederman * the vfs. 40990bd23d09SEric W. Biederman */ 41000bd23d09SEric W. Biederman if (HAS_UNMAPPED_ID(inode)) 41010bd23d09SEric W. Biederman return -EPERM; 4102acfa4380SAl Viro if (!dir->i_op->link) 41031da177e4SLinus Torvalds return -EPERM; 41047e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 41051da177e4SLinus Torvalds return -EPERM; 41061da177e4SLinus Torvalds 41071da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 41081da177e4SLinus Torvalds if (error) 41091da177e4SLinus Torvalds return error; 41101da177e4SLinus Torvalds 41115955102cSAl Viro inode_lock(inode); 4112aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4113f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4114aae8a97dSAneesh Kumar K.V error = -ENOENT; 41158de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 41168de52778SAl Viro error = -EMLINK; 4117146a8595SJ. Bruce Fields else { 4118146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4119146a8595SJ. Bruce Fields if (!error) 41201da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4121146a8595SJ. Bruce Fields } 4122f4e0c30cSAl Viro 4123f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4124f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4125f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4126f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4127f4e0c30cSAl Viro } 41285955102cSAl Viro inode_unlock(inode); 4129e31e14ecSStephen Smalley if (!error) 41307e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 41311da177e4SLinus Torvalds return error; 41321da177e4SLinus Torvalds } 41334d359507SAl Viro EXPORT_SYMBOL(vfs_link); 41341da177e4SLinus Torvalds 41351da177e4SLinus Torvalds /* 41361da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 41371da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 41381da177e4SLinus Torvalds * newname. --KAB 41391da177e4SLinus Torvalds * 41401da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 41411da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 41421da177e4SLinus Torvalds * and other special files. --ADM 41431da177e4SLinus Torvalds */ 414446ea89ebSDominik Brodowski int do_linkat(int olddfd, const char __user *oldname, int newdfd, 414546ea89ebSDominik Brodowski const char __user *newname, int flags) 41461da177e4SLinus Torvalds { 41471da177e4SLinus Torvalds struct dentry *new_dentry; 4148dae6ad8fSAl Viro struct path old_path, new_path; 4149146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 415011a7b371SAneesh Kumar K.V int how = 0; 41511da177e4SLinus Torvalds int error; 41521da177e4SLinus Torvalds 415311a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4154c04030e1SUlrich Drepper return -EINVAL; 415511a7b371SAneesh Kumar K.V /* 4156f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4157f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4158f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 415911a7b371SAneesh Kumar K.V */ 4160f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4161f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4162f0cc6ffbSLinus Torvalds return -ENOENT; 416311a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4164f0cc6ffbSLinus Torvalds } 4165c04030e1SUlrich Drepper 416611a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 416711a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4168442e31caSJeff Layton retry: 416911a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 41701da177e4SLinus Torvalds if (error) 41712ad94ae6SAl Viro return error; 41722ad94ae6SAl Viro 4173442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4174442e31caSJeff Layton (how & LOOKUP_REVAL)); 41751da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 41766902d925SDave Hansen if (IS_ERR(new_dentry)) 4177dae6ad8fSAl Viro goto out; 4178dae6ad8fSAl Viro 4179dae6ad8fSAl Viro error = -EXDEV; 4180dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4181dae6ad8fSAl Viro goto out_dput; 4182800179c9SKees Cook error = may_linkat(&old_path); 4183800179c9SKees Cook if (unlikely(error)) 4184800179c9SKees Cook goto out_dput; 4185dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4186be6d3e56SKentaro Takeda if (error) 4187a8104a9fSAl Viro goto out_dput; 4188146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 418975c3f29dSDave Hansen out_dput: 4190921a1650SAl Viro done_path_create(&new_path, new_dentry); 4191146a8595SJ. Bruce Fields if (delegated_inode) { 4192146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4193d22e6338SOleg Drokin if (!error) { 4194d22e6338SOleg Drokin path_put(&old_path); 4195146a8595SJ. Bruce Fields goto retry; 4196146a8595SJ. Bruce Fields } 4197d22e6338SOleg Drokin } 4198442e31caSJeff Layton if (retry_estale(error, how)) { 4199d22e6338SOleg Drokin path_put(&old_path); 4200442e31caSJeff Layton how |= LOOKUP_REVAL; 4201442e31caSJeff Layton goto retry; 4202442e31caSJeff Layton } 42031da177e4SLinus Torvalds out: 42042d8f3038SAl Viro path_put(&old_path); 42051da177e4SLinus Torvalds 42061da177e4SLinus Torvalds return error; 42071da177e4SLinus Torvalds } 42081da177e4SLinus Torvalds 420946ea89ebSDominik Brodowski SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 421046ea89ebSDominik Brodowski int, newdfd, const char __user *, newname, int, flags) 421146ea89ebSDominik Brodowski { 421246ea89ebSDominik Brodowski return do_linkat(olddfd, oldname, newdfd, newname, flags); 421346ea89ebSDominik Brodowski } 421446ea89ebSDominik Brodowski 42153480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 42165590ff0dSUlrich Drepper { 421746ea89ebSDominik Brodowski return do_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 42185590ff0dSUlrich Drepper } 42195590ff0dSUlrich Drepper 4220bc27027aSMiklos Szeredi /** 4221bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4222bc27027aSMiklos Szeredi * @old_dir: parent of source 4223bc27027aSMiklos Szeredi * @old_dentry: source 4224bc27027aSMiklos Szeredi * @new_dir: parent of destination 4225bc27027aSMiklos Szeredi * @new_dentry: destination 4226bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4227520c8b16SMiklos Szeredi * @flags: rename flags 4228bc27027aSMiklos Szeredi * 4229bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4230bc27027aSMiklos Szeredi * 4231bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4232bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4233bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4234bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4235bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4236bc27027aSMiklos Szeredi * so. 4237bc27027aSMiklos Szeredi * 4238bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4239bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4240bc27027aSMiklos Szeredi * to be NFS exported. 4241bc27027aSMiklos Szeredi * 42421da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 42431da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 42441da177e4SLinus Torvalds * Problems: 42450117d427SMauro Carvalho Chehab * 4246d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 42471da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 42481da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4249a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 42501da177e4SLinus Torvalds * story. 42516cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 42526cedba89SJ. Bruce Fields * and source (if it is not a directory). 42531b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 42541da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 42551da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4256a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 42571da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 42581da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 42591da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4260a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 42611da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 42621da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 42631da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4264e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 42651b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 42661da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4267c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 42681da177e4SLinus Torvalds * locking]. 42691da177e4SLinus Torvalds */ 42701da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 42718e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4272520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 42731da177e4SLinus Torvalds { 42741da177e4SLinus Torvalds int error; 4275bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 4276bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4277bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4278da1ce067SMiklos Szeredi bool new_is_dir = false; 4279da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 428049d31c2fSAl Viro struct name_snapshot old_name; 42811da177e4SLinus Torvalds 42828d3e2936SMiklos Szeredi if (source == target) 42831da177e4SLinus Torvalds return 0; 42841da177e4SLinus Torvalds 42851da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 42861da177e4SLinus Torvalds if (error) 42871da177e4SLinus Torvalds return error; 42881da177e4SLinus Torvalds 4289da1ce067SMiklos Szeredi if (!target) { 4290a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4291da1ce067SMiklos Szeredi } else { 4292da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4293da1ce067SMiklos Szeredi 4294da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 42951da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4296da1ce067SMiklos Szeredi else 4297da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4298da1ce067SMiklos Szeredi } 42991da177e4SLinus Torvalds if (error) 43001da177e4SLinus Torvalds return error; 43011da177e4SLinus Torvalds 43022773bf00SMiklos Szeredi if (!old_dir->i_op->rename) 43031da177e4SLinus Torvalds return -EPERM; 43041da177e4SLinus Torvalds 4305bc27027aSMiklos Szeredi /* 4306bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4307bc27027aSMiklos Szeredi * we'll need to flip '..'. 4308bc27027aSMiklos Szeredi */ 4309da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4310da1ce067SMiklos Szeredi if (is_dir) { 4311bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4312bc27027aSMiklos Szeredi if (error) 4313bc27027aSMiklos Szeredi return error; 4314bc27027aSMiklos Szeredi } 4315da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4316da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4317da1ce067SMiklos Szeredi if (error) 4318da1ce067SMiklos Szeredi return error; 4319da1ce067SMiklos Szeredi } 4320da1ce067SMiklos Szeredi } 43210eeca283SRobert Love 43220b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 43230b3974ebSMiklos Szeredi flags); 4324bc27027aSMiklos Szeredi if (error) 4325bc27027aSMiklos Szeredi return error; 4326bc27027aSMiklos Szeredi 432749d31c2fSAl Viro take_dentry_name_snapshot(&old_name, old_dentry); 4328bc27027aSMiklos Szeredi dget(new_dentry); 4329da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4330bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4331bc27027aSMiklos Szeredi else if (target) 43325955102cSAl Viro inode_lock(target); 4333bc27027aSMiklos Szeredi 4334bc27027aSMiklos Szeredi error = -EBUSY; 43357af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4336bc27027aSMiklos Szeredi goto out; 4337bc27027aSMiklos Szeredi 4338da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4339bc27027aSMiklos Szeredi error = -EMLINK; 4340da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4341bc27027aSMiklos Szeredi goto out; 4342da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4343da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4344da1ce067SMiklos Szeredi goto out; 4345da1ce067SMiklos Szeredi } 4346da1ce067SMiklos Szeredi if (!is_dir) { 4347bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4348bc27027aSMiklos Szeredi if (error) 4349bc27027aSMiklos Szeredi goto out; 4350da1ce067SMiklos Szeredi } 4351da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4352bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4353bc27027aSMiklos Szeredi if (error) 4354bc27027aSMiklos Szeredi goto out; 4355bc27027aSMiklos Szeredi } 4356520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4357520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4358bc27027aSMiklos Szeredi if (error) 4359bc27027aSMiklos Szeredi goto out; 4360bc27027aSMiklos Szeredi 4361da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 43628767712fSAl Viro if (is_dir) { 43638767712fSAl Viro shrink_dcache_parent(new_dentry); 4364bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 43658767712fSAl Viro } 4366bc27027aSMiklos Szeredi dont_mount(new_dentry); 43678ed936b5SEric W. Biederman detach_mounts(new_dentry); 4368bc27027aSMiklos Szeredi } 4369da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4370da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4371bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4372da1ce067SMiklos Szeredi else 4373da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4374da1ce067SMiklos Szeredi } 4375bc27027aSMiklos Szeredi out: 4376da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4377bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4378bc27027aSMiklos Szeredi else if (target) 43795955102cSAl Viro inode_unlock(target); 4380bc27027aSMiklos Szeredi dput(new_dentry); 4381da1ce067SMiklos Szeredi if (!error) { 4382f4ec3a3dSAl Viro fsnotify_move(old_dir, new_dir, &old_name.name, is_dir, 4383da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4384da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4385f4ec3a3dSAl Viro fsnotify_move(new_dir, old_dir, &old_dentry->d_name, 4386da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4387da1ce067SMiklos Szeredi } 4388da1ce067SMiklos Szeredi } 438949d31c2fSAl Viro release_dentry_name_snapshot(&old_name); 43900eeca283SRobert Love 43911da177e4SLinus Torvalds return error; 43921da177e4SLinus Torvalds } 43934d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 43941da177e4SLinus Torvalds 4395ee81feb6SDominik Brodowski static int do_renameat2(int olddfd, const char __user *oldname, int newdfd, 4396ee81feb6SDominik Brodowski const char __user *newname, unsigned int flags) 43971da177e4SLinus Torvalds { 43981da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 43991da177e4SLinus Torvalds struct dentry *trap; 4400f5beed75SAl Viro struct path old_path, new_path; 4401f5beed75SAl Viro struct qstr old_last, new_last; 4402f5beed75SAl Viro int old_type, new_type; 44038e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 440491a27b2aSJeff Layton struct filename *from; 440591a27b2aSJeff Layton struct filename *to; 4406f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4407c6a94284SJeff Layton bool should_retry = false; 44082ad94ae6SAl Viro int error; 4409520c8b16SMiklos Szeredi 44100d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4411da1ce067SMiklos Szeredi return -EINVAL; 4412da1ce067SMiklos Szeredi 44130d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 44140d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4415520c8b16SMiklos Szeredi return -EINVAL; 4416520c8b16SMiklos Szeredi 44170d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 44180d7a8555SMiklos Szeredi return -EPERM; 44190d7a8555SMiklos Szeredi 4420f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4421f5beed75SAl Viro target_flags = 0; 4422f5beed75SAl Viro 4423c6a94284SJeff Layton retry: 4424c1d4dd27SAl Viro from = filename_parentat(olddfd, getname(oldname), lookup_flags, 4425c1d4dd27SAl Viro &old_path, &old_last, &old_type); 442691a27b2aSJeff Layton if (IS_ERR(from)) { 442791a27b2aSJeff Layton error = PTR_ERR(from); 44281da177e4SLinus Torvalds goto exit; 442991a27b2aSJeff Layton } 44301da177e4SLinus Torvalds 4431c1d4dd27SAl Viro to = filename_parentat(newdfd, getname(newname), lookup_flags, 4432c1d4dd27SAl Viro &new_path, &new_last, &new_type); 443391a27b2aSJeff Layton if (IS_ERR(to)) { 443491a27b2aSJeff Layton error = PTR_ERR(to); 44351da177e4SLinus Torvalds goto exit1; 443691a27b2aSJeff Layton } 44371da177e4SLinus Torvalds 44381da177e4SLinus Torvalds error = -EXDEV; 4439f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 44401da177e4SLinus Torvalds goto exit2; 44411da177e4SLinus Torvalds 44421da177e4SLinus Torvalds error = -EBUSY; 4443f5beed75SAl Viro if (old_type != LAST_NORM) 44441da177e4SLinus Torvalds goto exit2; 44451da177e4SLinus Torvalds 44460a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 44470a7c3937SMiklos Szeredi error = -EEXIST; 4448f5beed75SAl Viro if (new_type != LAST_NORM) 44491da177e4SLinus Torvalds goto exit2; 44501da177e4SLinus Torvalds 4451f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4452c30dabfeSJan Kara if (error) 4453c30dabfeSJan Kara goto exit2; 4454c30dabfeSJan Kara 44558e6d782cSJ. Bruce Fields retry_deleg: 4456f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 44571da177e4SLinus Torvalds 4458f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 44591da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 44601da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 44611da177e4SLinus Torvalds goto exit3; 44621da177e4SLinus Torvalds /* source must exist */ 44631da177e4SLinus Torvalds error = -ENOENT; 4464b18825a7SDavid Howells if (d_is_negative(old_dentry)) 44651da177e4SLinus Torvalds goto exit4; 4466f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 44671da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 44681da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 44691da177e4SLinus Torvalds goto exit4; 44700a7c3937SMiklos Szeredi error = -EEXIST; 44710a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 44720a7c3937SMiklos Szeredi goto exit5; 4473da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4474da1ce067SMiklos Szeredi error = -ENOENT; 4475da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4476da1ce067SMiklos Szeredi goto exit5; 4477da1ce067SMiklos Szeredi 4478da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4479da1ce067SMiklos Szeredi error = -ENOTDIR; 4480f5beed75SAl Viro if (new_last.name[new_last.len]) 4481da1ce067SMiklos Szeredi goto exit5; 4482da1ce067SMiklos Szeredi } 4483da1ce067SMiklos Szeredi } 44840a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 44850a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 44860a7c3937SMiklos Szeredi error = -ENOTDIR; 4487f5beed75SAl Viro if (old_last.name[old_last.len]) 44880a7c3937SMiklos Szeredi goto exit5; 4489f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 44900a7c3937SMiklos Szeredi goto exit5; 44910a7c3937SMiklos Szeredi } 44920a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 44930a7c3937SMiklos Szeredi error = -EINVAL; 44940a7c3937SMiklos Szeredi if (old_dentry == trap) 44950a7c3937SMiklos Szeredi goto exit5; 44961da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4497da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 44981da177e4SLinus Torvalds error = -ENOTEMPTY; 44991da177e4SLinus Torvalds if (new_dentry == trap) 45001da177e4SLinus Torvalds goto exit5; 45011da177e4SLinus Torvalds 4502f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4503f5beed75SAl Viro &new_path, new_dentry, flags); 4504be6d3e56SKentaro Takeda if (error) 4505c30dabfeSJan Kara goto exit5; 4506f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4507f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4508520c8b16SMiklos Szeredi &delegated_inode, flags); 45091da177e4SLinus Torvalds exit5: 45101da177e4SLinus Torvalds dput(new_dentry); 45111da177e4SLinus Torvalds exit4: 45121da177e4SLinus Torvalds dput(old_dentry); 45131da177e4SLinus Torvalds exit3: 4514f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 45158e6d782cSJ. Bruce Fields if (delegated_inode) { 45168e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 45178e6d782cSJ. Bruce Fields if (!error) 45188e6d782cSJ. Bruce Fields goto retry_deleg; 45198e6d782cSJ. Bruce Fields } 4520f5beed75SAl Viro mnt_drop_write(old_path.mnt); 45211da177e4SLinus Torvalds exit2: 4522c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4523c6a94284SJeff Layton should_retry = true; 4524f5beed75SAl Viro path_put(&new_path); 45252ad94ae6SAl Viro putname(to); 45261da177e4SLinus Torvalds exit1: 4527f5beed75SAl Viro path_put(&old_path); 45281da177e4SLinus Torvalds putname(from); 4529c6a94284SJeff Layton if (should_retry) { 4530c6a94284SJeff Layton should_retry = false; 4531c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4532c6a94284SJeff Layton goto retry; 4533c6a94284SJeff Layton } 45342ad94ae6SAl Viro exit: 45351da177e4SLinus Torvalds return error; 45361da177e4SLinus Torvalds } 45371da177e4SLinus Torvalds 4538ee81feb6SDominik Brodowski SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4539ee81feb6SDominik Brodowski int, newdfd, const char __user *, newname, unsigned int, flags) 4540ee81feb6SDominik Brodowski { 4541ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, flags); 4542ee81feb6SDominik Brodowski } 4543ee81feb6SDominik Brodowski 4544520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4545520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4546520c8b16SMiklos Szeredi { 4547ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, 0); 4548520c8b16SMiklos Szeredi } 4549520c8b16SMiklos Szeredi 4550a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 45515590ff0dSUlrich Drepper { 4552ee81feb6SDominik Brodowski return do_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 45535590ff0dSUlrich Drepper } 45545590ff0dSUlrich Drepper 4555787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4556787fb6bcSMiklos Szeredi { 4557787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4558787fb6bcSMiklos Szeredi if (error) 4559787fb6bcSMiklos Szeredi return error; 4560787fb6bcSMiklos Szeredi 4561787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4562787fb6bcSMiklos Szeredi return -EPERM; 4563787fb6bcSMiklos Szeredi 4564787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4565787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4566787fb6bcSMiklos Szeredi } 4567787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4568787fb6bcSMiklos Szeredi 45695d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 45701da177e4SLinus Torvalds { 45715d826c84SAl Viro int len = PTR_ERR(link); 45721da177e4SLinus Torvalds if (IS_ERR(link)) 45731da177e4SLinus Torvalds goto out; 45741da177e4SLinus Torvalds 45751da177e4SLinus Torvalds len = strlen(link); 45761da177e4SLinus Torvalds if (len > (unsigned) buflen) 45771da177e4SLinus Torvalds len = buflen; 45781da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 45791da177e4SLinus Torvalds len = -EFAULT; 45801da177e4SLinus Torvalds out: 45811da177e4SLinus Torvalds return len; 45821da177e4SLinus Torvalds } 45831da177e4SLinus Torvalds 4584d60874cdSMiklos Szeredi /** 4585fd4a0edfSMiklos Szeredi * vfs_readlink - copy symlink body into userspace buffer 4586fd4a0edfSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4587fd4a0edfSMiklos Szeredi * @buffer: user memory pointer 4588fd4a0edfSMiklos Szeredi * @buflen: size of buffer 4589fd4a0edfSMiklos Szeredi * 4590fd4a0edfSMiklos Szeredi * Does not touch atime. That's up to the caller if necessary 4591fd4a0edfSMiklos Szeredi * 4592fd4a0edfSMiklos Szeredi * Does not call security hook. 4593fd4a0edfSMiklos Szeredi */ 4594fd4a0edfSMiklos Szeredi int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4595fd4a0edfSMiklos Szeredi { 4596fd4a0edfSMiklos Szeredi struct inode *inode = d_inode(dentry); 4597f2df5da6SAl Viro DEFINE_DELAYED_CALL(done); 4598f2df5da6SAl Viro const char *link; 4599f2df5da6SAl Viro int res; 4600fd4a0edfSMiklos Szeredi 460176fca90eSMiklos Szeredi if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) { 460276fca90eSMiklos Szeredi if (unlikely(inode->i_op->readlink)) 460376fca90eSMiklos Szeredi return inode->i_op->readlink(dentry, buffer, buflen); 460476fca90eSMiklos Szeredi 460576fca90eSMiklos Szeredi if (!d_is_symlink(dentry)) 4606fd4a0edfSMiklos Szeredi return -EINVAL; 4607fd4a0edfSMiklos Szeredi 460876fca90eSMiklos Szeredi spin_lock(&inode->i_lock); 460976fca90eSMiklos Szeredi inode->i_opflags |= IOP_DEFAULT_READLINK; 461076fca90eSMiklos Szeredi spin_unlock(&inode->i_lock); 461176fca90eSMiklos Szeredi } 461276fca90eSMiklos Szeredi 46134c4f7c19SEric Biggers link = READ_ONCE(inode->i_link); 4614f2df5da6SAl Viro if (!link) { 4615f2df5da6SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4616f2df5da6SAl Viro if (IS_ERR(link)) 4617f2df5da6SAl Viro return PTR_ERR(link); 4618f2df5da6SAl Viro } 4619f2df5da6SAl Viro res = readlink_copy(buffer, buflen, link); 4620f2df5da6SAl Viro do_delayed_call(&done); 4621f2df5da6SAl Viro return res; 4622fd4a0edfSMiklos Szeredi } 4623fd4a0edfSMiklos Szeredi EXPORT_SYMBOL(vfs_readlink); 46241da177e4SLinus Torvalds 4625d60874cdSMiklos Szeredi /** 4626d60874cdSMiklos Szeredi * vfs_get_link - get symlink body 4627d60874cdSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4628d60874cdSMiklos Szeredi * @done: caller needs to free returned data with this 4629d60874cdSMiklos Szeredi * 4630d60874cdSMiklos Szeredi * Calls security hook and i_op->get_link() on the supplied inode. 4631d60874cdSMiklos Szeredi * 4632d60874cdSMiklos Szeredi * It does not touch atime. That's up to the caller if necessary. 4633d60874cdSMiklos Szeredi * 4634d60874cdSMiklos Szeredi * Does not work on "special" symlinks like /proc/$$/fd/N 4635d60874cdSMiklos Szeredi */ 4636d60874cdSMiklos Szeredi const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done) 4637d60874cdSMiklos Szeredi { 4638d60874cdSMiklos Szeredi const char *res = ERR_PTR(-EINVAL); 4639d60874cdSMiklos Szeredi struct inode *inode = d_inode(dentry); 4640d60874cdSMiklos Szeredi 4641d60874cdSMiklos Szeredi if (d_is_symlink(dentry)) { 4642d60874cdSMiklos Szeredi res = ERR_PTR(security_inode_readlink(dentry)); 4643d60874cdSMiklos Szeredi if (!res) 4644d60874cdSMiklos Szeredi res = inode->i_op->get_link(dentry, inode, done); 4645d60874cdSMiklos Szeredi } 4646d60874cdSMiklos Szeredi return res; 4647d60874cdSMiklos Szeredi } 4648d60874cdSMiklos Szeredi EXPORT_SYMBOL(vfs_get_link); 4649d60874cdSMiklos Szeredi 46501da177e4SLinus Torvalds /* get the link contents into pagecache */ 46516b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4652fceef393SAl Viro struct delayed_call *callback) 46531da177e4SLinus Torvalds { 4654ebd09abbSDuane Griffin char *kaddr; 46551da177e4SLinus Torvalds struct page *page; 46566b255391SAl Viro struct address_space *mapping = inode->i_mapping; 46576b255391SAl Viro 4658d3883d4fSAl Viro if (!dentry) { 4659d3883d4fSAl Viro page = find_get_page(mapping, 0); 4660d3883d4fSAl Viro if (!page) 46616b255391SAl Viro return ERR_PTR(-ECHILD); 4662d3883d4fSAl Viro if (!PageUptodate(page)) { 4663d3883d4fSAl Viro put_page(page); 4664d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4665d3883d4fSAl Viro } 4666d3883d4fSAl Viro } else { 4667090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 46681da177e4SLinus Torvalds if (IS_ERR(page)) 46696fe6900eSNick Piggin return (char*)page; 4670d3883d4fSAl Viro } 4671fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 467221fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 467321fc61c7SAl Viro kaddr = page_address(page); 46746b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4675ebd09abbSDuane Griffin return kaddr; 46761da177e4SLinus Torvalds } 46771da177e4SLinus Torvalds 46786b255391SAl Viro EXPORT_SYMBOL(page_get_link); 46791da177e4SLinus Torvalds 4680fceef393SAl Viro void page_put_link(void *arg) 46811da177e4SLinus Torvalds { 4682fceef393SAl Viro put_page(arg); 46831da177e4SLinus Torvalds } 46844d359507SAl Viro EXPORT_SYMBOL(page_put_link); 46851da177e4SLinus Torvalds 4686aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4687aa80deabSAl Viro { 4688fceef393SAl Viro DEFINE_DELAYED_CALL(done); 46896b255391SAl Viro int res = readlink_copy(buffer, buflen, 46906b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4691fceef393SAl Viro &done)); 4692fceef393SAl Viro do_delayed_call(&done); 4693aa80deabSAl Viro return res; 4694aa80deabSAl Viro } 4695aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4696aa80deabSAl Viro 469754566b2cSNick Piggin /* 469854566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 469954566b2cSNick Piggin */ 470054566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 47011da177e4SLinus Torvalds { 47021da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 47030adb25d2SKirill Korotaev struct page *page; 4704afddba49SNick Piggin void *fsdata; 4705beb497abSDmitriy Monakhov int err; 4706c718a975STetsuo Handa unsigned int flags = 0; 470754566b2cSNick Piggin if (nofs) 470854566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 47091da177e4SLinus Torvalds 47107e53cac4SNeilBrown retry: 4711afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 471254566b2cSNick Piggin flags, &page, &fsdata); 47131da177e4SLinus Torvalds if (err) 4714afddba49SNick Piggin goto fail; 4715afddba49SNick Piggin 471621fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4717afddba49SNick Piggin 4718afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4719afddba49SNick Piggin page, fsdata); 47201da177e4SLinus Torvalds if (err < 0) 47211da177e4SLinus Torvalds goto fail; 4722afddba49SNick Piggin if (err < len-1) 4723afddba49SNick Piggin goto retry; 4724afddba49SNick Piggin 47251da177e4SLinus Torvalds mark_inode_dirty(inode); 47261da177e4SLinus Torvalds return 0; 47271da177e4SLinus Torvalds fail: 47281da177e4SLinus Torvalds return err; 47291da177e4SLinus Torvalds } 47304d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 47311da177e4SLinus Torvalds 47320adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 47330adb25d2SKirill Korotaev { 47340adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4735c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 47360adb25d2SKirill Korotaev } 47374d359507SAl Viro EXPORT_SYMBOL(page_symlink); 47380adb25d2SKirill Korotaev 473992e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 47406b255391SAl Viro .get_link = page_get_link, 47411da177e4SLinus Torvalds }; 47421da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4743