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 /** 553397d425dSEric W. Biederman * path_connected - Verify that a path->dentry is below path->mnt.mnt_root 554397d425dSEric W. Biederman * @path: nameidate to verify 555397d425dSEric W. Biederman * 556397d425dSEric W. Biederman * Rename can sometimes move a file or directory outside of a bind 557397d425dSEric W. Biederman * mount, path_connected allows those cases to be detected. 558397d425dSEric W. Biederman */ 559397d425dSEric W. Biederman static bool path_connected(const struct path *path) 560397d425dSEric W. Biederman { 561397d425dSEric W. Biederman struct vfsmount *mnt = path->mnt; 56295dd7758SEric W. Biederman struct super_block *sb = mnt->mnt_sb; 563397d425dSEric W. Biederman 56495dd7758SEric W. Biederman /* Bind mounts and multi-root filesystems can have disconnected paths */ 56595dd7758SEric W. Biederman if (!(sb->s_iflags & SB_I_MULTIROOT) && (mnt->mnt_root == sb->s_root)) 566397d425dSEric W. Biederman return true; 567397d425dSEric W. Biederman 568397d425dSEric W. Biederman return is_subdir(path->dentry, mnt->mnt_root); 569397d425dSEric W. Biederman } 570397d425dSEric W. Biederman 571894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 572894bc8c4SAl Viro { 573da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 574894bc8c4SAl Viro return 0; 575894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 576894bc8c4SAl Viro return 0; 577894bc8c4SAl Viro return __nd_alloc_stack(nd); 578894bc8c4SAl Viro } 579894bc8c4SAl Viro 5807973387aSAl Viro static void drop_links(struct nameidata *nd) 5817973387aSAl Viro { 5827973387aSAl Viro int i = nd->depth; 5837973387aSAl Viro while (i--) { 5847973387aSAl Viro struct saved *last = nd->stack + i; 585fceef393SAl Viro do_delayed_call(&last->done); 586fceef393SAl Viro clear_delayed_call(&last->done); 5877973387aSAl Viro } 5887973387aSAl Viro } 5897973387aSAl Viro 5907973387aSAl Viro static void terminate_walk(struct nameidata *nd) 5917973387aSAl Viro { 5927973387aSAl Viro drop_links(nd); 5937973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 5947973387aSAl Viro int i; 5957973387aSAl Viro path_put(&nd->path); 5967973387aSAl Viro for (i = 0; i < nd->depth; i++) 5977973387aSAl Viro path_put(&nd->stack[i].link); 59884a2bd39SAl Viro if (nd->flags & LOOKUP_ROOT_GRABBED) { 599102b8af2SAl Viro path_put(&nd->root); 60084a2bd39SAl Viro nd->flags &= ~LOOKUP_ROOT_GRABBED; 601102b8af2SAl Viro } 6027973387aSAl Viro } else { 6037973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 6047973387aSAl Viro rcu_read_unlock(); 6057973387aSAl Viro } 6067973387aSAl Viro nd->depth = 0; 6077973387aSAl Viro } 6087973387aSAl Viro 6097973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 6107973387aSAl Viro static bool legitimize_path(struct nameidata *nd, 6117973387aSAl Viro struct path *path, unsigned seq) 6127973387aSAl Viro { 6137973387aSAl Viro int res = __legitimize_mnt(path->mnt, nd->m_seq); 6147973387aSAl Viro if (unlikely(res)) { 6157973387aSAl Viro if (res > 0) 6167973387aSAl Viro path->mnt = NULL; 6177973387aSAl Viro path->dentry = NULL; 6187973387aSAl Viro return false; 6197973387aSAl Viro } 6207973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 6217973387aSAl Viro path->dentry = NULL; 6227973387aSAl Viro return false; 6237973387aSAl Viro } 6247973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6257973387aSAl Viro } 6267973387aSAl Viro 6277973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6287973387aSAl Viro { 6297973387aSAl Viro int i; 6307973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6317973387aSAl Viro struct saved *last = nd->stack + i; 6327973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6337973387aSAl Viro drop_links(nd); 6347973387aSAl Viro nd->depth = i + 1; 6357973387aSAl Viro return false; 6367973387aSAl Viro } 6377973387aSAl Viro } 6387973387aSAl Viro return true; 6397973387aSAl Viro } 6407973387aSAl Viro 641ee594bffSAl Viro static bool legitimize_root(struct nameidata *nd) 642ee594bffSAl Viro { 643adb21d2bSAleksa Sarai /* 644adb21d2bSAleksa Sarai * For scoped-lookups (where nd->root has been zeroed), we need to 645adb21d2bSAleksa Sarai * restart the whole lookup from scratch -- because set_root() is wrong 646adb21d2bSAleksa Sarai * for these lookups (nd->dfd is the root, not the filesystem root). 647adb21d2bSAleksa Sarai */ 648adb21d2bSAleksa Sarai if (!nd->root.mnt && (nd->flags & LOOKUP_IS_SCOPED)) 649adb21d2bSAleksa Sarai return false; 650adb21d2bSAleksa Sarai /* Nothing to do if nd->root is zero or is managed by the VFS user. */ 651ee594bffSAl Viro if (!nd->root.mnt || (nd->flags & LOOKUP_ROOT)) 652ee594bffSAl Viro return true; 65384a2bd39SAl Viro nd->flags |= LOOKUP_ROOT_GRABBED; 654ee594bffSAl Viro return legitimize_path(nd, &nd->root, nd->root_seq); 655ee594bffSAl Viro } 656ee594bffSAl Viro 65719660af7SAl Viro /* 65831e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 65919660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 66019660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 66157e3715cSMike Marshall * normal reference counts on dentries and vfsmounts to transition to ref-walk 66219660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 66319660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 66419660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 66519660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 66631e6b01fSNick Piggin */ 66731e6b01fSNick Piggin 66831e6b01fSNick Piggin /** 66919660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 67019660af7SAl Viro * @nd: nameidata pathwalk data 67139191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 67231e6b01fSNick Piggin * 6734675ac39SAl Viro * unlazy_walk attempts to legitimize the current nd->path and nd->root 6744675ac39SAl Viro * for ref-walk mode. 6754675ac39SAl Viro * Must be called from rcu-walk context. 6767973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6777973387aSAl Viro * terminate_walk(). 67831e6b01fSNick Piggin */ 6794675ac39SAl Viro static int unlazy_walk(struct nameidata *nd) 68031e6b01fSNick Piggin { 68131e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 68231e6b01fSNick Piggin 68331e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 684e5c832d5SLinus Torvalds 685e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6867973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6874675ac39SAl Viro goto out1; 68884a2bd39SAl Viro if (unlikely(!legitimize_path(nd, &nd->path, nd->seq))) 68984a2bd39SAl Viro goto out; 690ee594bffSAl Viro if (unlikely(!legitimize_root(nd))) 6914675ac39SAl Viro goto out; 6924675ac39SAl Viro rcu_read_unlock(); 6934675ac39SAl Viro BUG_ON(nd->inode != parent->d_inode); 6944675ac39SAl Viro return 0; 6954675ac39SAl Viro 69684a2bd39SAl Viro out1: 6974675ac39SAl Viro nd->path.mnt = NULL; 6984675ac39SAl Viro nd->path.dentry = NULL; 6994675ac39SAl Viro out: 7004675ac39SAl Viro rcu_read_unlock(); 7014675ac39SAl Viro return -ECHILD; 7024675ac39SAl Viro } 7034675ac39SAl Viro 7044675ac39SAl Viro /** 7054675ac39SAl Viro * unlazy_child - try to switch to ref-walk mode. 7064675ac39SAl Viro * @nd: nameidata pathwalk data 7074675ac39SAl Viro * @dentry: child of nd->path.dentry 7084675ac39SAl Viro * @seq: seq number to check dentry against 7094675ac39SAl Viro * Returns: 0 on success, -ECHILD on failure 7104675ac39SAl Viro * 7114675ac39SAl Viro * unlazy_child attempts to legitimize the current nd->path, nd->root and dentry 7124675ac39SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 7134675ac39SAl Viro * @nd. Must be called from rcu-walk context. 7144675ac39SAl Viro * Nothing should touch nameidata between unlazy_child() failure and 7154675ac39SAl Viro * terminate_walk(). 7164675ac39SAl Viro */ 7174675ac39SAl Viro static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned seq) 7184675ac39SAl Viro { 7194675ac39SAl Viro BUG_ON(!(nd->flags & LOOKUP_RCU)); 7204675ac39SAl Viro 7214675ac39SAl Viro nd->flags &= ~LOOKUP_RCU; 7224675ac39SAl Viro if (unlikely(!legitimize_links(nd))) 7234675ac39SAl Viro goto out2; 7247973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 7257973387aSAl Viro goto out2; 7264675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&nd->path.dentry->d_lockref))) 7277973387aSAl Viro goto out1; 72848a066e7SAl Viro 72915570086SLinus Torvalds /* 7304675ac39SAl Viro * We need to move both the parent and the dentry from the RCU domain 7314675ac39SAl Viro * to be properly refcounted. And the sequence number in the dentry 7324675ac39SAl Viro * validates *both* dentry counters, since we checked the sequence 7334675ac39SAl Viro * number of the parent after we got the child sequence number. So we 7344675ac39SAl Viro * know the parent must still be valid if the child sequence number is 73515570086SLinus Torvalds */ 7364675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) 737e5c832d5SLinus Torvalds goto out; 73884a2bd39SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 73984a2bd39SAl Viro goto out_dput; 740e5c832d5SLinus Torvalds /* 741e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 742e5c832d5SLinus Torvalds * still valid and get it if required. 743e5c832d5SLinus Torvalds */ 74484a2bd39SAl Viro if (unlikely(!legitimize_root(nd))) 74584a2bd39SAl Viro goto out_dput; 7468b61e74fSAl Viro rcu_read_unlock(); 74731e6b01fSNick Piggin return 0; 74819660af7SAl Viro 7497973387aSAl Viro out2: 7507973387aSAl Viro nd->path.mnt = NULL; 7517973387aSAl Viro out1: 7527973387aSAl Viro nd->path.dentry = NULL; 753e5c832d5SLinus Torvalds out: 7548b61e74fSAl Viro rcu_read_unlock(); 75584a2bd39SAl Viro return -ECHILD; 75684a2bd39SAl Viro out_dput: 75784a2bd39SAl Viro rcu_read_unlock(); 75884a2bd39SAl Viro dput(dentry); 75931e6b01fSNick Piggin return -ECHILD; 76031e6b01fSNick Piggin } 76131e6b01fSNick Piggin 7624ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 76334286d66SNick Piggin { 764a89f8337SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 7654ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 766a89f8337SAl Viro else 767a89f8337SAl Viro return 1; 76834286d66SNick Piggin } 76934286d66SNick Piggin 7709f1fafeeSAl Viro /** 7719f1fafeeSAl Viro * complete_walk - successful completion of path walk 7729f1fafeeSAl Viro * @nd: pointer nameidata 77339159de2SJeff Layton * 7749f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7759f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7769f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7779f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7789f1fafeeSAl Viro * need to drop nd->path. 77939159de2SJeff Layton */ 7809f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 78139159de2SJeff Layton { 78216c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 78339159de2SJeff Layton int status; 78439159de2SJeff Layton 7859f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 786adb21d2bSAleksa Sarai /* 787adb21d2bSAleksa Sarai * We don't want to zero nd->root for scoped-lookups or 788adb21d2bSAleksa Sarai * externally-managed nd->root. 789adb21d2bSAleksa Sarai */ 790adb21d2bSAleksa Sarai if (!(nd->flags & (LOOKUP_ROOT | LOOKUP_IS_SCOPED))) 7919f1fafeeSAl Viro nd->root.mnt = NULL; 7924675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 79348a066e7SAl Viro return -ECHILD; 79448a066e7SAl Viro } 7959f1fafeeSAl Viro 796adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) { 797adb21d2bSAleksa Sarai /* 798adb21d2bSAleksa Sarai * While the guarantee of LOOKUP_IS_SCOPED is (roughly) "don't 799adb21d2bSAleksa Sarai * ever step outside the root during lookup" and should already 800adb21d2bSAleksa Sarai * be guaranteed by the rest of namei, we want to avoid a namei 801adb21d2bSAleksa Sarai * BUG resulting in userspace being given a path that was not 802adb21d2bSAleksa Sarai * scoped within the root at some point during the lookup. 803adb21d2bSAleksa Sarai * 804adb21d2bSAleksa Sarai * So, do a final sanity-check to make sure that in the 805adb21d2bSAleksa Sarai * worst-case scenario (a complete bypass of LOOKUP_IS_SCOPED) 806adb21d2bSAleksa Sarai * we won't silently return an fd completely outside of the 807adb21d2bSAleksa Sarai * requested root to userspace. 808adb21d2bSAleksa Sarai * 809adb21d2bSAleksa Sarai * Userspace could move the path outside the root after this 810adb21d2bSAleksa Sarai * check, but as discussed elsewhere this is not a concern (the 811adb21d2bSAleksa Sarai * resolved file was inside the root at some point). 812adb21d2bSAleksa Sarai */ 813adb21d2bSAleksa Sarai if (!path_is_under(&nd->path, &nd->root)) 814adb21d2bSAleksa Sarai return -EXDEV; 815adb21d2bSAleksa Sarai } 816adb21d2bSAleksa Sarai 81716c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 81839159de2SJeff Layton return 0; 81939159de2SJeff Layton 820ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 82116c2cd71SAl Viro return 0; 82216c2cd71SAl Viro 823ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 82439159de2SJeff Layton if (status > 0) 82539159de2SJeff Layton return 0; 82639159de2SJeff Layton 82716c2cd71SAl Viro if (!status) 82839159de2SJeff Layton status = -ESTALE; 82916c2cd71SAl Viro 83039159de2SJeff Layton return status; 83139159de2SJeff Layton } 83239159de2SJeff Layton 833740a1678SAleksa Sarai static int set_root(struct nameidata *nd) 8342a737871SAl Viro { 83531e6b01fSNick Piggin struct fs_struct *fs = current->fs; 8369e6697e2SAl Viro 837adb21d2bSAleksa Sarai /* 838adb21d2bSAleksa Sarai * Jumping to the real root in a scoped-lookup is a BUG in namei, but we 839adb21d2bSAleksa Sarai * still have to ensure it doesn't happen because it will cause a breakout 840adb21d2bSAleksa Sarai * from the dirfd. 841adb21d2bSAleksa Sarai */ 842adb21d2bSAleksa Sarai if (WARN_ON(nd->flags & LOOKUP_IS_SCOPED)) 843adb21d2bSAleksa Sarai return -ENOTRECOVERABLE; 844adb21d2bSAleksa Sarai 8459e6697e2SAl Viro if (nd->flags & LOOKUP_RCU) { 8468f47a016SAl Viro unsigned seq; 847c28cc364SNick Piggin 848c28cc364SNick Piggin do { 849c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 85031e6b01fSNick Piggin nd->root = fs->root; 8518f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 852c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 8539e6697e2SAl Viro } else { 8549e6697e2SAl Viro get_fs_root(fs, &nd->root); 85584a2bd39SAl Viro nd->flags |= LOOKUP_ROOT_GRABBED; 8569e6697e2SAl Viro } 857740a1678SAleksa Sarai return 0; 85831e6b01fSNick Piggin } 85931e6b01fSNick Piggin 8607b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8617b9337aaSNick Piggin struct nameidata *nd) 862051d3812SIan Kent { 86331e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8644ac91378SJan Blunck dput(nd->path.dentry); 86531e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8664ac91378SJan Blunck mntput(nd->path.mnt); 8679a229683SHuang Shijie } 86831e6b01fSNick Piggin nd->path.mnt = path->mnt; 8694ac91378SJan Blunck nd->path.dentry = path->dentry; 870051d3812SIan Kent } 871051d3812SIan Kent 872248fb5b9SAl Viro static int nd_jump_root(struct nameidata *nd) 873248fb5b9SAl Viro { 874adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_BENEATH)) 875adb21d2bSAleksa Sarai return -EXDEV; 87672ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) { 87772ba2929SAleksa Sarai /* Absolute path arguments to path_init() are allowed. */ 87872ba2929SAleksa Sarai if (nd->path.mnt != NULL && nd->path.mnt != nd->root.mnt) 87972ba2929SAleksa Sarai return -EXDEV; 88072ba2929SAleksa Sarai } 881740a1678SAleksa Sarai if (!nd->root.mnt) { 882740a1678SAleksa Sarai int error = set_root(nd); 883740a1678SAleksa Sarai if (error) 884740a1678SAleksa Sarai return error; 885740a1678SAleksa Sarai } 886248fb5b9SAl Viro if (nd->flags & LOOKUP_RCU) { 887248fb5b9SAl Viro struct dentry *d; 888248fb5b9SAl Viro nd->path = nd->root; 889248fb5b9SAl Viro d = nd->path.dentry; 890248fb5b9SAl Viro nd->inode = d->d_inode; 891248fb5b9SAl Viro nd->seq = nd->root_seq; 892248fb5b9SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 893248fb5b9SAl Viro return -ECHILD; 894248fb5b9SAl Viro } else { 895248fb5b9SAl Viro path_put(&nd->path); 896248fb5b9SAl Viro nd->path = nd->root; 897248fb5b9SAl Viro path_get(&nd->path); 898248fb5b9SAl Viro nd->inode = nd->path.dentry->d_inode; 899248fb5b9SAl Viro } 900248fb5b9SAl Viro nd->flags |= LOOKUP_JUMPED; 901248fb5b9SAl Viro return 0; 902248fb5b9SAl Viro } 903248fb5b9SAl Viro 904b5fb63c1SChristoph Hellwig /* 9056b255391SAl Viro * Helper to directly jump to a known parsed path from ->get_link, 906b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 907b5fb63c1SChristoph Hellwig */ 9081bc82070SAleksa Sarai int nd_jump_link(struct path *path) 909b5fb63c1SChristoph Hellwig { 9104b99d499SAleksa Sarai int error = -ELOOP; 9116e77137bSAl Viro struct nameidata *nd = current->nameidata; 912b5fb63c1SChristoph Hellwig 9134b99d499SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_MAGICLINKS)) 9144b99d499SAleksa Sarai goto err; 9154b99d499SAleksa Sarai 91672ba2929SAleksa Sarai error = -EXDEV; 91772ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) { 91872ba2929SAleksa Sarai if (nd->path.mnt != path->mnt) 91972ba2929SAleksa Sarai goto err; 92072ba2929SAleksa Sarai } 921adb21d2bSAleksa Sarai /* Not currently safe for scoped-lookups. */ 922adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) 923adb21d2bSAleksa Sarai goto err; 92472ba2929SAleksa Sarai 9254b99d499SAleksa Sarai path_put(&nd->path); 926b5fb63c1SChristoph Hellwig nd->path = *path; 927b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 928b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 9291bc82070SAleksa Sarai return 0; 9304b99d499SAleksa Sarai 9314b99d499SAleksa Sarai err: 9324b99d499SAleksa Sarai path_put(path); 9334b99d499SAleksa Sarai return error; 934b5fb63c1SChristoph Hellwig } 935b5fb63c1SChristoph Hellwig 936b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 937574197e0SAl Viro { 93821c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 939fceef393SAl Viro do_delayed_call(&last->done); 9406548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 941b9ff4429SAl Viro path_put(&last->link); 942574197e0SAl Viro } 943574197e0SAl Viro 944561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 945561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 94630aba665SSalvatore Mesoraca int sysctl_protected_fifos __read_mostly; 94730aba665SSalvatore Mesoraca int sysctl_protected_regular __read_mostly; 948800179c9SKees Cook 949800179c9SKees Cook /** 950800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 95155852635SRandy Dunlap * @nd: nameidata pathwalk data 952800179c9SKees Cook * 953800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 954800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 955800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 956800179c9SKees Cook * processes from failing races against path names that may change out 957800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 958800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 959800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 960800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 961800179c9SKees Cook * 962800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 963800179c9SKees Cook */ 964ad6cc4c3SAl Viro static inline int may_follow_link(struct nameidata *nd, const struct inode *inode) 965800179c9SKees Cook { 966800179c9SKees Cook const struct inode *parent; 9672d7f9e2aSSeth Forshee kuid_t puid; 968800179c9SKees Cook 969800179c9SKees Cook if (!sysctl_protected_symlinks) 970800179c9SKees Cook return 0; 971800179c9SKees Cook 972800179c9SKees Cook /* Allowed if owner and follower match. */ 97381abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 974800179c9SKees Cook return 0; 975800179c9SKees Cook 976800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 977aa65fa35SAl Viro parent = nd->inode; 978800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 979800179c9SKees Cook return 0; 980800179c9SKees Cook 981800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 9822d7f9e2aSSeth Forshee puid = parent->i_uid; 9832d7f9e2aSSeth Forshee if (uid_valid(puid) && uid_eq(puid, inode->i_uid)) 984800179c9SKees Cook return 0; 985800179c9SKees Cook 98631956502SAl Viro if (nd->flags & LOOKUP_RCU) 98731956502SAl Viro return -ECHILD; 98831956502SAl Viro 989ea841bafSRichard Guy Briggs audit_inode(nd->name, nd->stack[0].link.dentry, 0); 990245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "follow_link"); 991800179c9SKees Cook return -EACCES; 992800179c9SKees Cook } 993800179c9SKees Cook 994800179c9SKees Cook /** 995800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 996800179c9SKees Cook * @inode: the source inode to hardlink from 997800179c9SKees Cook * 998800179c9SKees Cook * Return false if at least one of the following conditions: 999800179c9SKees Cook * - inode is not a regular file 1000800179c9SKees Cook * - inode is setuid 1001800179c9SKees Cook * - inode is setgid and group-exec 1002800179c9SKees Cook * - access failure for read and write 1003800179c9SKees Cook * 1004800179c9SKees Cook * Otherwise returns true. 1005800179c9SKees Cook */ 1006800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 1007800179c9SKees Cook { 1008800179c9SKees Cook umode_t mode = inode->i_mode; 1009800179c9SKees Cook 1010800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 1011800179c9SKees Cook if (!S_ISREG(mode)) 1012800179c9SKees Cook return false; 1013800179c9SKees Cook 1014800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 1015800179c9SKees Cook if (mode & S_ISUID) 1016800179c9SKees Cook return false; 1017800179c9SKees Cook 1018800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 1019800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 1020800179c9SKees Cook return false; 1021800179c9SKees Cook 1022800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 1023800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 1024800179c9SKees Cook return false; 1025800179c9SKees Cook 1026800179c9SKees Cook return true; 1027800179c9SKees Cook } 1028800179c9SKees Cook 1029800179c9SKees Cook /** 1030800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 1031800179c9SKees Cook * @link: the source to hardlink from 1032800179c9SKees Cook * 1033800179c9SKees Cook * Block hardlink when all of: 1034800179c9SKees Cook * - sysctl_protected_hardlinks enabled 1035800179c9SKees Cook * - fsuid does not match inode 1036800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 1037f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 1038800179c9SKees Cook * 1039800179c9SKees Cook * Returns 0 if successful, -ve on error. 1040800179c9SKees Cook */ 1041800179c9SKees Cook static int may_linkat(struct path *link) 1042800179c9SKees Cook { 1043593d1ce8SEric W. Biederman struct inode *inode = link->dentry->d_inode; 1044593d1ce8SEric W. Biederman 1045593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 1046593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 1047593d1ce8SEric W. Biederman return -EOVERFLOW; 1048800179c9SKees Cook 1049800179c9SKees Cook if (!sysctl_protected_hardlinks) 1050800179c9SKees Cook return 0; 1051800179c9SKees Cook 1052800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 1053800179c9SKees Cook * otherwise, it must be a safe source. 1054800179c9SKees Cook */ 1055cc658db4SKees Cook if (safe_hardlink_source(inode) || inode_owner_or_capable(inode)) 1056800179c9SKees Cook return 0; 1057800179c9SKees Cook 1058245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "linkat"); 1059800179c9SKees Cook return -EPERM; 1060800179c9SKees Cook } 1061800179c9SKees Cook 106230aba665SSalvatore Mesoraca /** 106330aba665SSalvatore Mesoraca * may_create_in_sticky - Check whether an O_CREAT open in a sticky directory 106430aba665SSalvatore Mesoraca * should be allowed, or not, on files that already 106530aba665SSalvatore Mesoraca * exist. 1066d0cb5018SAl Viro * @dir_mode: mode bits of directory 1067d0cb5018SAl Viro * @dir_uid: owner of directory 106830aba665SSalvatore Mesoraca * @inode: the inode of the file to open 106930aba665SSalvatore Mesoraca * 107030aba665SSalvatore Mesoraca * Block an O_CREAT open of a FIFO (or a regular file) when: 107130aba665SSalvatore Mesoraca * - sysctl_protected_fifos (or sysctl_protected_regular) is enabled 107230aba665SSalvatore Mesoraca * - the file already exists 107330aba665SSalvatore Mesoraca * - we are in a sticky directory 107430aba665SSalvatore Mesoraca * - we don't own the file 107530aba665SSalvatore Mesoraca * - the owner of the directory doesn't own the file 107630aba665SSalvatore Mesoraca * - the directory is world writable 107730aba665SSalvatore Mesoraca * If the sysctl_protected_fifos (or sysctl_protected_regular) is set to 2 107830aba665SSalvatore Mesoraca * the directory doesn't have to be world writable: being group writable will 107930aba665SSalvatore Mesoraca * be enough. 108030aba665SSalvatore Mesoraca * 108130aba665SSalvatore Mesoraca * Returns 0 if the open is allowed, -ve on error. 108230aba665SSalvatore Mesoraca */ 1083d0cb5018SAl Viro static int may_create_in_sticky(umode_t dir_mode, kuid_t dir_uid, 108430aba665SSalvatore Mesoraca struct inode * const inode) 108530aba665SSalvatore Mesoraca { 108630aba665SSalvatore Mesoraca if ((!sysctl_protected_fifos && S_ISFIFO(inode->i_mode)) || 108730aba665SSalvatore Mesoraca (!sysctl_protected_regular && S_ISREG(inode->i_mode)) || 1088d0cb5018SAl Viro likely(!(dir_mode & S_ISVTX)) || 1089d0cb5018SAl Viro uid_eq(inode->i_uid, dir_uid) || 109030aba665SSalvatore Mesoraca uid_eq(current_fsuid(), inode->i_uid)) 109130aba665SSalvatore Mesoraca return 0; 109230aba665SSalvatore Mesoraca 1093d0cb5018SAl Viro if (likely(dir_mode & 0002) || 1094d0cb5018SAl Viro (dir_mode & 0020 && 109530aba665SSalvatore Mesoraca ((sysctl_protected_fifos >= 2 && S_ISFIFO(inode->i_mode)) || 109630aba665SSalvatore Mesoraca (sysctl_protected_regular >= 2 && S_ISREG(inode->i_mode))))) { 1097245d7369SKees Cook const char *operation = S_ISFIFO(inode->i_mode) ? 1098245d7369SKees Cook "sticky_create_fifo" : 1099245d7369SKees Cook "sticky_create_regular"; 1100245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_CREAT, operation); 110130aba665SSalvatore Mesoraca return -EACCES; 110230aba665SSalvatore Mesoraca } 110330aba665SSalvatore Mesoraca return 0; 110430aba665SSalvatore Mesoraca } 110530aba665SSalvatore Mesoraca 1106f015f126SDavid Howells /* 1107f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1108f015f126SDavid Howells * 1109f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1110f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1111f015f126SDavid Howells * Up is towards /. 1112f015f126SDavid Howells * 1113f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1114f015f126SDavid Howells * root. 1115f015f126SDavid Howells */ 1116bab77ebfSAl Viro int follow_up(struct path *path) 11171da177e4SLinus Torvalds { 11180714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 11190714a533SAl Viro struct mount *parent; 11201da177e4SLinus Torvalds struct dentry *mountpoint; 112199b7db7bSNick Piggin 112248a066e7SAl Viro read_seqlock_excl(&mount_lock); 11230714a533SAl Viro parent = mnt->mnt_parent; 11243c0a6163SAl Viro if (parent == mnt) { 112548a066e7SAl Viro read_sequnlock_excl(&mount_lock); 11261da177e4SLinus Torvalds return 0; 11271da177e4SLinus Torvalds } 11280714a533SAl Viro mntget(&parent->mnt); 1129a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 113048a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1131bab77ebfSAl Viro dput(path->dentry); 1132bab77ebfSAl Viro path->dentry = mountpoint; 1133bab77ebfSAl Viro mntput(path->mnt); 11340714a533SAl Viro path->mnt = &parent->mnt; 11351da177e4SLinus Torvalds return 1; 11361da177e4SLinus Torvalds } 11374d359507SAl Viro EXPORT_SYMBOL(follow_up); 11381da177e4SLinus Torvalds 1139b5c84bf6SNick Piggin /* 11409875cf80SDavid Howells * Perform an automount 11419875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 11429875cf80SDavid Howells * were called with. 11431da177e4SLinus Torvalds */ 11441c9f5e06SAl Viro static int follow_automount(struct path *path, int *count, unsigned lookup_flags) 114531e6b01fSNick Piggin { 114625e195aaSAl Viro struct dentry *dentry = path->dentry; 11479875cf80SDavid Howells 11480ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 11490ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 11500ec26fd0SMiklos Szeredi * the name. 11510ec26fd0SMiklos Szeredi * 11520ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 11535a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 11540ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 11550ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 11560ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 11570ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 11585a30d8a2SDavid Howells */ 11591c9f5e06SAl Viro if (!(lookup_flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 11605d38f049SIan Kent LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 116125e195aaSAl Viro dentry->d_inode) 11629875cf80SDavid Howells return -EISDIR; 11630ec26fd0SMiklos Szeredi 11641c9f5e06SAl Viro if (count && (*count)++ >= MAXSYMLINKS) 11659875cf80SDavid Howells return -ELOOP; 11669875cf80SDavid Howells 116725e195aaSAl Viro return finish_automount(dentry->d_op->d_automount(path), path); 1168ea5b778aSDavid Howells } 11699875cf80SDavid Howells 11709875cf80SDavid Howells /* 11719875cf80SDavid Howells * Handle a dentry that is managed in some way. 1172cc53ce53SDavid Howells * - Flagged for transit management (autofs) 11739875cf80SDavid Howells * - Flagged as mountpoint 11749875cf80SDavid Howells * - Flagged as automount point 11759875cf80SDavid Howells * 11769875cf80SDavid Howells * This may only be called in refwalk mode. 1177d41efb52SAl Viro * On success path->dentry is known positive. 11789875cf80SDavid Howells * 11799875cf80SDavid Howells * Serialization is taken care of in namespace.c 11809875cf80SDavid Howells */ 1181756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 11829875cf80SDavid Howells { 11838aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 1184d41efb52SAl Viro unsigned flags; 11859875cf80SDavid Howells bool need_mntput = false; 11868aef1884SAl Viro int ret = 0; 11879875cf80SDavid Howells 11889875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 11899875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 11909875cf80SDavid Howells * the components of that value change under us */ 11912fa6b1e0SAl Viro while (flags = smp_load_acquire(&path->dentry->d_flags), 1192d41efb52SAl Viro unlikely(flags & DCACHE_MANAGED_DENTRY)) { 1193cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1194cc53ce53SDavid Howells * being held. */ 1195d41efb52SAl Viro if (flags & DCACHE_MANAGE_TRANSIT) { 1196cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1197cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1198fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1199508c8772SAl Viro flags = smp_load_acquire(&path->dentry->d_flags); 1200cc53ce53SDavid Howells if (ret < 0) 12018aef1884SAl Viro break; 1202cc53ce53SDavid Howells } 1203cc53ce53SDavid Howells 12049875cf80SDavid Howells /* Transit to a mounted filesystem. */ 1205d41efb52SAl Viro if (flags & DCACHE_MOUNTED) { 12069875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12079875cf80SDavid Howells if (mounted) { 12089875cf80SDavid Howells dput(path->dentry); 12099875cf80SDavid Howells if (need_mntput) 1210463ffb2eSAl Viro mntput(path->mnt); 1211463ffb2eSAl Viro path->mnt = mounted; 1212463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 12139875cf80SDavid Howells need_mntput = true; 12149875cf80SDavid Howells continue; 1215463ffb2eSAl Viro } 1216463ffb2eSAl Viro 12179875cf80SDavid Howells /* Something is mounted on this dentry in another 12189875cf80SDavid Howells * namespace and/or whatever was mounted there in this 121948a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 122048a066e7SAl Viro * get it */ 12211da177e4SLinus Torvalds } 12229875cf80SDavid Howells 12239875cf80SDavid Howells /* Handle an automount point */ 1224d41efb52SAl Viro if (flags & DCACHE_NEED_AUTOMOUNT) { 12251c9f5e06SAl Viro ret = follow_automount(path, &nd->total_link_count, 12261c9f5e06SAl Viro nd->flags); 12279875cf80SDavid Howells if (ret < 0) 12288aef1884SAl Viro break; 12299875cf80SDavid Howells continue; 12309875cf80SDavid Howells } 12319875cf80SDavid Howells 12329875cf80SDavid Howells /* We didn't change the current path point */ 12339875cf80SDavid Howells break; 12349875cf80SDavid Howells } 12358aef1884SAl Viro 123672ba2929SAleksa Sarai if (need_mntput) { 123772ba2929SAleksa Sarai if (path->mnt == mnt) 12388aef1884SAl Viro mntput(path->mnt); 123972ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 124072ba2929SAleksa Sarai ret = -EXDEV; 124172ba2929SAleksa Sarai else 12428402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 124372ba2929SAleksa Sarai } 1244d41efb52SAl Viro if (ret == -EISDIR || !ret) 1245d41efb52SAl Viro ret = 1; 1246d41efb52SAl Viro if (ret > 0 && unlikely(d_flags_negative(flags))) 1247d41efb52SAl Viro ret = -ENOENT; 1248a9dc1494SAl Viro if (unlikely(ret < 0)) { 1249a9dc1494SAl Viro dput(path->dentry); 1250a9dc1494SAl Viro if (path->mnt != nd->path.mnt) 1251a9dc1494SAl Viro mntput(path->mnt); 1252a9dc1494SAl Viro } 12538402752eSAl Viro return ret; 12541da177e4SLinus Torvalds } 12551da177e4SLinus Torvalds 1256cc53ce53SDavid Howells int follow_down_one(struct path *path) 12571da177e4SLinus Torvalds { 12581da177e4SLinus Torvalds struct vfsmount *mounted; 12591da177e4SLinus Torvalds 12601c755af4SAl Viro mounted = lookup_mnt(path); 12611da177e4SLinus Torvalds if (mounted) { 12629393bd07SAl Viro dput(path->dentry); 12639393bd07SAl Viro mntput(path->mnt); 12649393bd07SAl Viro path->mnt = mounted; 12659393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12661da177e4SLinus Torvalds return 1; 12671da177e4SLinus Torvalds } 12681da177e4SLinus Torvalds return 0; 12691da177e4SLinus Torvalds } 12704d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12711da177e4SLinus Torvalds 1272fb5f51c7SIan Kent static inline int managed_dentry_rcu(const struct path *path) 127362a7375eSIan Kent { 1274fb5f51c7SIan Kent return (path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1275fb5f51c7SIan Kent path->dentry->d_op->d_manage(path, true) : 0; 127662a7375eSIan Kent } 127762a7375eSIan Kent 12789875cf80SDavid Howells /* 1279287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1280287548e4SAl Viro * we meet a managed dentry that would need blocking. 12819875cf80SDavid Howells */ 12829875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1283254cf582SAl Viro struct inode **inode, unsigned *seqp) 12849875cf80SDavid Howells { 128562a7375eSIan Kent for (;;) { 1286c7105365SAl Viro struct mount *mounted; 128762a7375eSIan Kent /* 128862a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 128962a7375eSIan Kent * that wants to block transit. 129062a7375eSIan Kent */ 1291fb5f51c7SIan Kent switch (managed_dentry_rcu(path)) { 1292b8faf035SNeilBrown case -ECHILD: 1293b8faf035SNeilBrown default: 1294ab90911fSDavid Howells return false; 1295b8faf035SNeilBrown case -EISDIR: 1296b8faf035SNeilBrown return true; 1297b8faf035SNeilBrown case 0: 1298b8faf035SNeilBrown break; 1299b8faf035SNeilBrown } 130062a7375eSIan Kent 130162a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1302b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 130362a7375eSIan Kent 1304474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 13059875cf80SDavid Howells if (!mounted) 13069875cf80SDavid Howells break; 130772ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 130872ba2929SAleksa Sarai return false; 1309c7105365SAl Viro path->mnt = &mounted->mnt; 1310c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1311a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1312254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 131359430262SLinus Torvalds /* 131459430262SLinus Torvalds * Update the inode too. We don't need to re-check the 131559430262SLinus Torvalds * dentry sequence number here after this d_inode read, 131659430262SLinus Torvalds * because a mount-point is always pinned. 131759430262SLinus Torvalds */ 131859430262SLinus Torvalds *inode = path->dentry->d_inode; 13199875cf80SDavid Howells } 1320f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1321b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1322287548e4SAl Viro } 1323287548e4SAl Viro 1324db3c9adeSAl Viro static inline int handle_mounts(struct nameidata *nd, struct dentry *dentry, 1325db3c9adeSAl Viro struct path *path, struct inode **inode, 1326db3c9adeSAl Viro unsigned int *seqp) 1327bd7c4b50SAl Viro { 1328db3c9adeSAl Viro int ret; 1329bd7c4b50SAl Viro 1330db3c9adeSAl Viro path->mnt = nd->path.mnt; 1331db3c9adeSAl Viro path->dentry = dentry; 1332c153007bSAl Viro if (nd->flags & LOOKUP_RCU) { 1333c153007bSAl Viro unsigned int seq = *seqp; 1334c153007bSAl Viro if (unlikely(!*inode)) 1335c153007bSAl Viro return -ENOENT; 1336c153007bSAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 1337c153007bSAl Viro return 1; 1338c153007bSAl Viro if (unlazy_child(nd, dentry, seq)) 1339c153007bSAl Viro return -ECHILD; 1340c153007bSAl Viro // *path might've been clobbered by __follow_mount_rcu() 1341c153007bSAl Viro path->mnt = nd->path.mnt; 1342c153007bSAl Viro path->dentry = dentry; 1343c153007bSAl Viro } 1344db3c9adeSAl Viro ret = follow_managed(path, nd); 1345bd7c4b50SAl Viro if (likely(ret >= 0)) { 1346bd7c4b50SAl Viro *inode = d_backing_inode(path->dentry); 1347bd7c4b50SAl Viro *seqp = 0; /* out of RCU mode, so the value doesn't matter */ 1348bd7c4b50SAl Viro } 1349bd7c4b50SAl Viro return ret; 1350bd7c4b50SAl Viro } 1351bd7c4b50SAl Viro 135231e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 135331e6b01fSNick Piggin { 13544023bfc9SAl Viro struct inode *inode = nd->inode; 135531e6b01fSNick Piggin 135631e6b01fSNick Piggin while (1) { 1357adb21d2bSAleksa Sarai if (path_equal(&nd->path, &nd->root)) { 1358adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_BENEATH)) 1359adb21d2bSAleksa Sarai return -ECHILD; 136031e6b01fSNick Piggin break; 1361adb21d2bSAleksa Sarai } 136231e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 136331e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 136431e6b01fSNick Piggin struct dentry *parent = old->d_parent; 136531e6b01fSNick Piggin unsigned seq; 136631e6b01fSNick Piggin 13674023bfc9SAl Viro inode = parent->d_inode; 136831e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 1369aed434adSAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 1370aed434adSAl Viro return -ECHILD; 137131e6b01fSNick Piggin nd->path.dentry = parent; 137231e6b01fSNick Piggin nd->seq = seq; 1373397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 13742b98149cSAleksa Sarai return -ECHILD; 137531e6b01fSNick Piggin break; 1376aed434adSAl Viro } else { 1377aed434adSAl Viro struct mount *mnt = real_mount(nd->path.mnt); 1378aed434adSAl Viro struct mount *mparent = mnt->mnt_parent; 1379aed434adSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1380aed434adSAl Viro struct inode *inode2 = mountpoint->d_inode; 1381aed434adSAl Viro unsigned seq = read_seqcount_begin(&mountpoint->d_seq); 1382aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1383aed434adSAl Viro return -ECHILD; 1384aed434adSAl Viro if (&mparent->mnt == nd->path.mnt) 138531e6b01fSNick Piggin break; 138672ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 138772ba2929SAleksa Sarai return -ECHILD; 1388aed434adSAl Viro /* we know that mountpoint was pinned */ 1389aed434adSAl Viro nd->path.dentry = mountpoint; 1390aed434adSAl Viro nd->path.mnt = &mparent->mnt; 1391aed434adSAl Viro inode = inode2; 1392aed434adSAl Viro nd->seq = seq; 139331e6b01fSNick Piggin } 1394aed434adSAl Viro } 1395aed434adSAl Viro while (unlikely(d_mountpoint(nd->path.dentry))) { 1396b37199e6SAl Viro struct mount *mounted; 1397b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1398aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1399aed434adSAl Viro return -ECHILD; 1400b37199e6SAl Viro if (!mounted) 1401b37199e6SAl Viro break; 140272ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 140372ba2929SAleksa Sarai return -ECHILD; 1404b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1405b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 14064023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1407b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1408b37199e6SAl Viro } 14094023bfc9SAl Viro nd->inode = inode; 141031e6b01fSNick Piggin return 0; 141131e6b01fSNick Piggin } 141231e6b01fSNick Piggin 14139875cf80SDavid Howells /* 1414cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1415cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1416cc53ce53SDavid Howells * caller is permitted to proceed or not. 1417cc53ce53SDavid Howells */ 14187cc90cc3SAl Viro int follow_down(struct path *path) 1419cc53ce53SDavid Howells { 1420cc53ce53SDavid Howells unsigned managed; 1421cc53ce53SDavid Howells int ret; 1422cc53ce53SDavid Howells 14236aa7de05SMark Rutland while (managed = READ_ONCE(path->dentry->d_flags), 1424cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1425cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1426cc53ce53SDavid Howells * being held. 1427cc53ce53SDavid Howells * 1428cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1429cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1430cc53ce53SDavid Howells * other than its daemon the right to mount on its 1431cc53ce53SDavid Howells * superstructure. 1432cc53ce53SDavid Howells * 1433cc53ce53SDavid Howells * The filesystem may sleep at this point. 1434cc53ce53SDavid Howells */ 1435cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1436cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1437cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1438fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1439cc53ce53SDavid Howells if (ret < 0) 1440cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1441cc53ce53SDavid Howells } 1442cc53ce53SDavid Howells 1443cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1444cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1445cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1446cc53ce53SDavid Howells if (!mounted) 1447cc53ce53SDavid Howells break; 1448cc53ce53SDavid Howells dput(path->dentry); 1449cc53ce53SDavid Howells mntput(path->mnt); 1450cc53ce53SDavid Howells path->mnt = mounted; 1451cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1452cc53ce53SDavid Howells continue; 1453cc53ce53SDavid Howells } 1454cc53ce53SDavid Howells 1455cc53ce53SDavid Howells /* Don't handle automount points here */ 1456cc53ce53SDavid Howells break; 1457cc53ce53SDavid Howells } 1458cc53ce53SDavid Howells return 0; 1459cc53ce53SDavid Howells } 14604d359507SAl Viro EXPORT_SYMBOL(follow_down); 1461cc53ce53SDavid Howells 1462cc53ce53SDavid Howells /* 14639875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 14649875cf80SDavid Howells */ 14659875cf80SDavid Howells static void follow_mount(struct path *path) 14669875cf80SDavid Howells { 14679875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 14689875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 14699875cf80SDavid Howells if (!mounted) 14709875cf80SDavid Howells break; 14719875cf80SDavid Howells dput(path->dentry); 14729875cf80SDavid Howells mntput(path->mnt); 14739875cf80SDavid Howells path->mnt = mounted; 14749875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 14759875cf80SDavid Howells } 14769875cf80SDavid Howells } 14779875cf80SDavid Howells 1478eedf265aSEric W. Biederman static int path_parent_directory(struct path *path) 1479eedf265aSEric W. Biederman { 1480eedf265aSEric W. Biederman struct dentry *old = path->dentry; 1481eedf265aSEric W. Biederman /* rare case of legitimate dget_parent()... */ 1482eedf265aSEric W. Biederman path->dentry = dget_parent(path->dentry); 1483eedf265aSEric W. Biederman dput(old); 1484eedf265aSEric W. Biederman if (unlikely(!path_connected(path))) 1485eedf265aSEric W. Biederman return -ENOENT; 1486eedf265aSEric W. Biederman return 0; 1487eedf265aSEric W. Biederman } 1488eedf265aSEric W. Biederman 1489397d425dSEric W. Biederman static int follow_dotdot(struct nameidata *nd) 14901da177e4SLinus Torvalds { 14911da177e4SLinus Torvalds while (1) { 1492adb21d2bSAleksa Sarai if (path_equal(&nd->path, &nd->root)) { 1493adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_BENEATH)) 1494adb21d2bSAleksa Sarai return -EXDEV; 14951da177e4SLinus Torvalds break; 1496adb21d2bSAleksa Sarai } 14974ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 1498eedf265aSEric W. Biederman int ret = path_parent_directory(&nd->path); 1499eedf265aSEric W. Biederman if (ret) 1500eedf265aSEric W. Biederman return ret; 15011da177e4SLinus Torvalds break; 15021da177e4SLinus Torvalds } 15033088dd70SAl Viro if (!follow_up(&nd->path)) 15041da177e4SLinus Torvalds break; 150572ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 150672ba2929SAleksa Sarai return -EXDEV; 15071da177e4SLinus Torvalds } 150879ed0226SAl Viro follow_mount(&nd->path); 150931e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 1510397d425dSEric W. Biederman return 0; 15111da177e4SLinus Torvalds } 15121da177e4SLinus Torvalds 15131da177e4SLinus Torvalds /* 1514f4fdace9SOleg Drokin * This looks up the name in dcache and possibly revalidates the found dentry. 1515f4fdace9SOleg Drokin * NULL is returned if the dentry does not exist in the cache. 1516baa03890SNick Piggin */ 1517e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1518e3c13928SAl Viro struct dentry *dir, 15196c51e513SAl Viro unsigned int flags) 1520baa03890SNick Piggin { 1521a89f8337SAl Viro struct dentry *dentry = d_lookup(dir, name); 1522bad61189SMiklos Szeredi if (dentry) { 1523a89f8337SAl Viro int error = d_revalidate(dentry, flags); 1524bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 152574ff0ffcSAl Viro if (!error) 15265542aa2fSEric W. Biederman d_invalidate(dentry); 1527bad61189SMiklos Szeredi dput(dentry); 152874ff0ffcSAl Viro return ERR_PTR(error); 1529bad61189SMiklos Szeredi } 1530bad61189SMiklos Szeredi } 1531baa03890SNick Piggin return dentry; 1532baa03890SNick Piggin } 1533baa03890SNick Piggin 1534baa03890SNick Piggin /* 1535a03ece5fSAl Viro * Parent directory has inode locked exclusive. This is one 1536a03ece5fSAl Viro * and only case when ->lookup() gets called on non in-lookup 1537a03ece5fSAl Viro * dentries - as the matter of fact, this only gets called 1538a03ece5fSAl Viro * when directory is guaranteed to have no in-lookup children 1539a03ece5fSAl Viro * at all. 154044396f4bSJosef Bacik */ 1541a03ece5fSAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 1542a03ece5fSAl Viro struct dentry *base, unsigned int flags) 154344396f4bSJosef Bacik { 1544a03ece5fSAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 154544396f4bSJosef Bacik struct dentry *old; 1546a03ece5fSAl Viro struct inode *dir = base->d_inode; 1547a03ece5fSAl Viro 1548a03ece5fSAl Viro if (dentry) 1549a03ece5fSAl Viro return dentry; 155044396f4bSJosef Bacik 155144396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1552a03ece5fSAl Viro if (unlikely(IS_DEADDIR(dir))) 155344396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1554a03ece5fSAl Viro 1555a03ece5fSAl Viro dentry = d_alloc(base, name); 1556a03ece5fSAl Viro if (unlikely(!dentry)) 1557a03ece5fSAl Viro return ERR_PTR(-ENOMEM); 155844396f4bSJosef Bacik 155972bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 156044396f4bSJosef Bacik if (unlikely(old)) { 156144396f4bSJosef Bacik dput(dentry); 156244396f4bSJosef Bacik dentry = old; 156344396f4bSJosef Bacik } 156444396f4bSJosef Bacik return dentry; 156544396f4bSJosef Bacik } 156644396f4bSJosef Bacik 156720e34357SAl Viro static struct dentry *lookup_fast(struct nameidata *nd, 156820e34357SAl Viro struct inode **inode, 1569254cf582SAl Viro unsigned *seqp) 15701da177e4SLinus Torvalds { 157131e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 15725a18fff2SAl Viro int status = 1; 15739875cf80SDavid Howells 15743cac260aSAl Viro /* 1575b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 15765d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 15775d0f49c1SAl Viro * going to fall back to non-racy lookup. 1578b04f784eSNick Piggin */ 157931e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 158031e6b01fSNick Piggin unsigned seq; 1581da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15825d0f49c1SAl Viro if (unlikely(!dentry)) { 15834675ac39SAl Viro if (unlazy_walk(nd)) 158420e34357SAl Viro return ERR_PTR(-ECHILD); 158520e34357SAl Viro return NULL; 15865d0f49c1SAl Viro } 15875a18fff2SAl Viro 158812f8ad4bSLinus Torvalds /* 158912f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 159012f8ad4bSLinus Torvalds * the dentry name information from lookup. 159112f8ad4bSLinus Torvalds */ 159263afdfc7SDavid Howells *inode = d_backing_inode(dentry); 15935d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 159420e34357SAl Viro return ERR_PTR(-ECHILD); 159512f8ad4bSLinus Torvalds 159612f8ad4bSLinus Torvalds /* 159712f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 159812f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 159912f8ad4bSLinus Torvalds * 160012f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 160112f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 160212f8ad4bSLinus Torvalds */ 16035d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 160420e34357SAl Viro return ERR_PTR(-ECHILD); 16055a18fff2SAl Viro 1606254cf582SAl Viro *seqp = seq; 16074ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 1608c153007bSAl Viro if (likely(status > 0)) 160920e34357SAl Viro return dentry; 16104675ac39SAl Viro if (unlazy_child(nd, dentry, seq)) 161120e34357SAl Viro return ERR_PTR(-ECHILD); 1612209a7fb2SAl Viro if (unlikely(status == -ECHILD)) 1613209a7fb2SAl Viro /* we'd been told to redo it in non-rcu mode */ 1614209a7fb2SAl Viro status = d_revalidate(dentry, nd->flags); 16155a18fff2SAl Viro } else { 1616e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 161781e6f520SAl Viro if (unlikely(!dentry)) 161820e34357SAl Viro return NULL; 16194ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 16205d0f49c1SAl Viro } 16215a18fff2SAl Viro if (unlikely(status <= 0)) { 1622e9742b53SAl Viro if (!status) 16235d0f49c1SAl Viro d_invalidate(dentry); 16245a18fff2SAl Viro dput(dentry); 162520e34357SAl Viro return ERR_PTR(status); 16265a18fff2SAl Viro } 162720e34357SAl Viro return dentry; 1628697f514dSMiklos Szeredi } 1629697f514dSMiklos Szeredi 1630697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 163188d8331aSAl Viro static struct dentry *__lookup_slow(const struct qstr *name, 1632e3c13928SAl Viro struct dentry *dir, 1633e3c13928SAl Viro unsigned int flags) 1634697f514dSMiklos Szeredi { 163588d8331aSAl Viro struct dentry *dentry, *old; 16361936386eSAl Viro struct inode *inode = dir->d_inode; 1637d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 16381936386eSAl Viro 16391936386eSAl Viro /* Don't go there if it's already dead */ 164094bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 164188d8331aSAl Viro return ERR_PTR(-ENOENT); 164294bdd655SAl Viro again: 1643d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 164494bdd655SAl Viro if (IS_ERR(dentry)) 164588d8331aSAl Viro return dentry; 164694bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1647949a852eSAl Viro int error = d_revalidate(dentry, flags); 1648949a852eSAl Viro if (unlikely(error <= 0)) { 164994bdd655SAl Viro if (!error) { 1650949a852eSAl Viro d_invalidate(dentry); 1651949a852eSAl Viro dput(dentry); 165294bdd655SAl Viro goto again; 165394bdd655SAl Viro } 165494bdd655SAl Viro dput(dentry); 1655949a852eSAl Viro dentry = ERR_PTR(error); 1656949a852eSAl Viro } 165794bdd655SAl Viro } else { 16581936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 165985c7f810SAl Viro d_lookup_done(dentry); 16601936386eSAl Viro if (unlikely(old)) { 16611936386eSAl Viro dput(dentry); 16621936386eSAl Viro dentry = old; 1663949a852eSAl Viro } 1664949a852eSAl Viro } 1665e3c13928SAl Viro return dentry; 16661da177e4SLinus Torvalds } 16671da177e4SLinus Torvalds 166888d8331aSAl Viro static struct dentry *lookup_slow(const struct qstr *name, 166988d8331aSAl Viro struct dentry *dir, 167088d8331aSAl Viro unsigned int flags) 167188d8331aSAl Viro { 167288d8331aSAl Viro struct inode *inode = dir->d_inode; 167388d8331aSAl Viro struct dentry *res; 167488d8331aSAl Viro inode_lock_shared(inode); 167588d8331aSAl Viro res = __lookup_slow(name, dir, flags); 167688d8331aSAl Viro inode_unlock_shared(inode); 167788d8331aSAl Viro return res; 167888d8331aSAl Viro } 167988d8331aSAl Viro 168052094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 168152094c8aSAl Viro { 168252094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16834ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 168452094c8aSAl Viro if (err != -ECHILD) 168552094c8aSAl Viro return err; 16864675ac39SAl Viro if (unlazy_walk(nd)) 168752094c8aSAl Viro return -ECHILD; 168852094c8aSAl Viro } 16894ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 169052094c8aSAl Viro } 169152094c8aSAl Viro 16929856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 16939856fa1bSAl Viro { 16949856fa1bSAl Viro if (type == LAST_DOTDOT) { 1695740a1678SAleksa Sarai int error = 0; 1696740a1678SAleksa Sarai 1697740a1678SAleksa Sarai if (!nd->root.mnt) { 1698740a1678SAleksa Sarai error = set_root(nd); 1699740a1678SAleksa Sarai if (error) 1700740a1678SAleksa Sarai return error; 1701740a1678SAleksa Sarai } 1702ab87f9a5SAleksa Sarai if (nd->flags & LOOKUP_RCU) 1703ab87f9a5SAleksa Sarai error = follow_dotdot_rcu(nd); 1704ab87f9a5SAleksa Sarai else 1705ab87f9a5SAleksa Sarai error = follow_dotdot(nd); 1706ab87f9a5SAleksa Sarai if (error) 1707ab87f9a5SAleksa Sarai return error; 1708ab87f9a5SAleksa Sarai 1709ab87f9a5SAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) { 1710ab87f9a5SAleksa Sarai /* 1711ab87f9a5SAleksa Sarai * If there was a racing rename or mount along our 1712ab87f9a5SAleksa Sarai * path, then we can't be sure that ".." hasn't jumped 1713ab87f9a5SAleksa Sarai * above nd->root (and so userspace should retry or use 1714ab87f9a5SAleksa Sarai * some fallback). 1715ab87f9a5SAleksa Sarai */ 1716ab87f9a5SAleksa Sarai smp_rmb(); 1717ab87f9a5SAleksa Sarai if (unlikely(__read_seqcount_retry(&mount_lock.seqcount, nd->m_seq))) 1718ab87f9a5SAleksa Sarai return -EAGAIN; 1719ab87f9a5SAleksa Sarai if (unlikely(__read_seqcount_retry(&rename_lock.seqcount, nd->r_seq))) 1720ab87f9a5SAleksa Sarai return -EAGAIN; 1721ab87f9a5SAleksa Sarai } 17229856fa1bSAl Viro } 17239856fa1bSAl Viro return 0; 17249856fa1bSAl Viro } 17259856fa1bSAl Viro 1726b1a81972SAl Viro enum {WALK_TRAILING = 1, WALK_MORE = 2, WALK_NOFOLLOW = 4}; 1727b1a81972SAl Viro 172806708adbSAl Viro static const char *pick_link(struct nameidata *nd, struct path *link, 1729b1a81972SAl Viro struct inode *inode, unsigned seq, int flags) 1730d63ff28fSAl Viro { 17311cf2665bSAl Viro struct saved *last; 1732ad6cc4c3SAl Viro const char *res; 1733ad6cc4c3SAl Viro int error; 1734ad6cc4c3SAl Viro 1735756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1736626de996SAl Viro path_to_nameidata(link, nd); 173706708adbSAl Viro return ERR_PTR(-ELOOP); 1738626de996SAl Viro } 1739bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1740cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1741cd179f44SAl Viro mntget(link->mnt); 17427973387aSAl Viro } 1743626de996SAl Viro error = nd_alloc_stack(nd); 1744626de996SAl Viro if (unlikely(error)) { 1745bc40aee0SAl Viro if (error == -ECHILD) { 1746ad1633a1SAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 1747ad1633a1SAl Viro drop_links(nd); 1748ad1633a1SAl Viro nd->depth = 0; 1749ad1633a1SAl Viro nd->flags &= ~LOOKUP_RCU; 1750ad1633a1SAl Viro nd->path.mnt = NULL; 1751ad1633a1SAl Viro nd->path.dentry = NULL; 1752ad1633a1SAl Viro rcu_read_unlock(); 17534675ac39SAl Viro } else if (likely(unlazy_walk(nd)) == 0) 1754bc40aee0SAl Viro error = nd_alloc_stack(nd); 1755bc40aee0SAl Viro } 1756bc40aee0SAl Viro if (error) { 1757cd179f44SAl Viro path_put(link); 175806708adbSAl Viro return ERR_PTR(error); 1759626de996SAl Viro } 1760bc40aee0SAl Viro } 1761626de996SAl Viro 1762ab104923SAl Viro last = nd->stack + nd->depth++; 17631cf2665bSAl Viro last->link = *link; 1764fceef393SAl Viro clear_delayed_call(&last->done); 17650450b2d1SAl Viro last->seq = seq; 1766ad6cc4c3SAl Viro 1767b1a81972SAl Viro if (flags & WALK_TRAILING) { 1768ad6cc4c3SAl Viro error = may_follow_link(nd, inode); 1769ad6cc4c3SAl Viro if (unlikely(error)) 1770ad6cc4c3SAl Viro return ERR_PTR(error); 1771ad6cc4c3SAl Viro } 1772ad6cc4c3SAl Viro 1773ad6cc4c3SAl Viro if (unlikely(nd->flags & LOOKUP_NO_SYMLINKS)) 1774ad6cc4c3SAl Viro return ERR_PTR(-ELOOP); 1775ad6cc4c3SAl Viro 1776ad6cc4c3SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1777ad6cc4c3SAl Viro touch_atime(&last->link); 1778ad6cc4c3SAl Viro cond_resched(); 1779ad6cc4c3SAl Viro } else if (atime_needs_update(&last->link, inode)) { 1780ad6cc4c3SAl Viro if (unlikely(unlazy_walk(nd))) 1781ad6cc4c3SAl Viro return ERR_PTR(-ECHILD); 1782ad6cc4c3SAl Viro touch_atime(&last->link); 1783ad6cc4c3SAl Viro } 1784ad6cc4c3SAl Viro 1785ad6cc4c3SAl Viro error = security_inode_follow_link(link->dentry, inode, 1786ad6cc4c3SAl Viro nd->flags & LOOKUP_RCU); 1787ad6cc4c3SAl Viro if (unlikely(error)) 1788ad6cc4c3SAl Viro return ERR_PTR(error); 1789ad6cc4c3SAl Viro 1790ad6cc4c3SAl Viro res = READ_ONCE(inode->i_link); 1791ad6cc4c3SAl Viro if (!res) { 1792ad6cc4c3SAl Viro const char * (*get)(struct dentry *, struct inode *, 1793ad6cc4c3SAl Viro struct delayed_call *); 1794ad6cc4c3SAl Viro get = inode->i_op->get_link; 1795ad6cc4c3SAl Viro if (nd->flags & LOOKUP_RCU) { 1796ad6cc4c3SAl Viro res = get(NULL, inode, &last->done); 1797ad6cc4c3SAl Viro if (res == ERR_PTR(-ECHILD)) { 1798ad6cc4c3SAl Viro if (unlikely(unlazy_walk(nd))) 1799ad6cc4c3SAl Viro return ERR_PTR(-ECHILD); 1800ad6cc4c3SAl Viro res = get(link->dentry, inode, &last->done); 1801ad6cc4c3SAl Viro } 1802ad6cc4c3SAl Viro } else { 1803ad6cc4c3SAl Viro res = get(link->dentry, inode, &last->done); 1804ad6cc4c3SAl Viro } 1805ad6cc4c3SAl Viro if (!res) 1806ad6cc4c3SAl Viro goto all_done; 1807ad6cc4c3SAl Viro if (IS_ERR(res)) 1808ad6cc4c3SAl Viro return res; 1809ad6cc4c3SAl Viro } 1810ad6cc4c3SAl Viro if (*res == '/') { 1811ad6cc4c3SAl Viro error = nd_jump_root(nd); 1812ad6cc4c3SAl Viro if (unlikely(error)) 1813ad6cc4c3SAl Viro return ERR_PTR(error); 1814ad6cc4c3SAl Viro while (unlikely(*++res == '/')) 1815ad6cc4c3SAl Viro ; 1816ad6cc4c3SAl Viro } 1817ad6cc4c3SAl Viro if (*res) 1818ad6cc4c3SAl Viro return res; 1819ad6cc4c3SAl Viro all_done: // pure jump 1820ad6cc4c3SAl Viro put_link(nd); 1821ad6cc4c3SAl Viro return NULL; 1822d63ff28fSAl Viro } 1823d63ff28fSAl Viro 18243ddcd056SLinus Torvalds /* 18253ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 18263ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 18273ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 18283ddcd056SLinus Torvalds * for the common case. 18293ddcd056SLinus Torvalds */ 1830b0417d2cSAl Viro static const char *step_into(struct nameidata *nd, int flags, 1831cbae4d12SAl Viro struct dentry *dentry, struct inode *inode, unsigned seq) 18323ddcd056SLinus Torvalds { 1833cbae4d12SAl Viro struct path path; 1834cbae4d12SAl Viro int err = handle_mounts(nd, dentry, &path, &inode, &seq); 1835cbae4d12SAl Viro 1836cbae4d12SAl Viro if (err < 0) 1837b0417d2cSAl Viro return ERR_PTR(err); 1838cbae4d12SAl Viro if (likely(!d_is_symlink(path.dentry)) || 18398c4efe22SAl Viro ((flags & WALK_TRAILING) && !(nd->flags & LOOKUP_FOLLOW)) || 1840aca2903eSAl Viro (flags & WALK_NOFOLLOW)) { 18418f64fb1cSAl Viro /* not a symlink or should not follow */ 1842cbae4d12SAl Viro path_to_nameidata(&path, nd); 18438f64fb1cSAl Viro nd->inode = inode; 18448f64fb1cSAl Viro nd->seq = seq; 1845b0417d2cSAl Viro return NULL; 18468f64fb1cSAl Viro } 1847a7f77542SAl Viro /* make sure that d_is_symlink above matches inode */ 1848a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 1849cbae4d12SAl Viro if (read_seqcount_retry(&path.dentry->d_seq, seq)) 1850b0417d2cSAl Viro return ERR_PTR(-ECHILD); 1851a7f77542SAl Viro } 1852b1a81972SAl Viro return pick_link(nd, &path, inode, seq, flags); 18533ddcd056SLinus Torvalds } 18543ddcd056SLinus Torvalds 185592d27016SAl Viro static const char *walk_component(struct nameidata *nd, int flags) 1856ce57dfc1SAl Viro { 1857db3c9adeSAl Viro struct dentry *dentry; 1858ce57dfc1SAl Viro struct inode *inode; 1859254cf582SAl Viro unsigned seq; 1860ce57dfc1SAl Viro int err; 1861ce57dfc1SAl Viro /* 1862ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1863ce57dfc1SAl Viro * to be able to know about the current root directory and 1864ce57dfc1SAl Viro * parent relationships. 1865ce57dfc1SAl Viro */ 18664693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 18671c4ff1a8SAl Viro if (!(flags & WALK_MORE) && nd->depth) 18684693a547SAl Viro put_link(nd); 186956676ec3SAl Viro err = handle_dots(nd, nd->last_type); 187092d27016SAl Viro return ERR_PTR(err); 18714693a547SAl Viro } 187220e34357SAl Viro dentry = lookup_fast(nd, &inode, &seq); 187320e34357SAl Viro if (IS_ERR(dentry)) 187492d27016SAl Viro return ERR_CAST(dentry); 187520e34357SAl Viro if (unlikely(!dentry)) { 1876db3c9adeSAl Viro dentry = lookup_slow(&nd->last, nd->path.dentry, nd->flags); 1877db3c9adeSAl Viro if (IS_ERR(dentry)) 187892d27016SAl Viro return ERR_CAST(dentry); 187920e34357SAl Viro } 188056676ec3SAl Viro if (!(flags & WALK_MORE) && nd->depth) 188156676ec3SAl Viro put_link(nd); 1882b0417d2cSAl Viro return step_into(nd, flags, dentry, inode, seq); 1883ce57dfc1SAl Viro } 1884ce57dfc1SAl Viro 18851da177e4SLinus Torvalds /* 1886bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1887bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1888bfcfaa77SLinus Torvalds * 1889bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1890bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1891bfcfaa77SLinus Torvalds * fast. 1892bfcfaa77SLinus Torvalds * 1893bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1894bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1895bfcfaa77SLinus Torvalds * crossing operation. 1896bfcfaa77SLinus Torvalds * 1897bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1898bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1899bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1900bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1901bfcfaa77SLinus Torvalds */ 1902bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1903bfcfaa77SLinus Torvalds 1904f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1905bfcfaa77SLinus Torvalds 1906468a9428SGeorge Spelvin #ifdef HASH_MIX 1907bfcfaa77SLinus Torvalds 1908468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1909468a9428SGeorge Spelvin 1910468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 19112a18da7aSGeorge Spelvin /* 19122a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 19132a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 19142a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 19152a18da7aSGeorge Spelvin * and no temporaries. 19162a18da7aSGeorge Spelvin * 19172a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 19182a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 19192a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 19202a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 19212a18da7aSGeorge Spelvin * 19222a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 19232a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 19242a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 19252a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 19262a18da7aSGeorge Spelvin * 19272a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 19282a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 19292a18da7aSGeorge Spelvin * toggling any given output bit. 19302a18da7aSGeorge Spelvin * 19312a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 19322a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 19332a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 19342a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 19352a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 19362a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 19372a18da7aSGeorge Spelvin * Perfect: 8192 258048 19382a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 19392a18da7aSGeorge Spelvin */ 19402a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 19412a18da7aSGeorge Spelvin ( x ^= (a), \ 19422a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 19432a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 19442a18da7aSGeorge Spelvin y *= 9 ) 1945bfcfaa77SLinus Torvalds 19460fed3ac8SGeorge Spelvin /* 19472a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 19482a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 19492a18da7aSGeorge Spelvin * work done before the hash value is used. 19500fed3ac8SGeorge Spelvin */ 19512a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 19520fed3ac8SGeorge Spelvin { 19532a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 19542a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 19552a18da7aSGeorge Spelvin return y >> 32; 19560fed3ac8SGeorge Spelvin } 19570fed3ac8SGeorge Spelvin 1958bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1959bfcfaa77SLinus Torvalds 19602a18da7aSGeorge Spelvin /* 19612a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 19622a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 19632a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 19642a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 19652a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 19662a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 19672a18da7aSGeorge Spelvin * Perfect: 2048 31744 19682a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 19692a18da7aSGeorge Spelvin */ 19702a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 19712a18da7aSGeorge Spelvin ( x ^= (a), \ 19722a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 19732a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 19742a18da7aSGeorge Spelvin y *= 9 ) 1975bfcfaa77SLinus Torvalds 19762a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 19770fed3ac8SGeorge Spelvin { 19782a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 19792a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 19800fed3ac8SGeorge Spelvin } 19810fed3ac8SGeorge Spelvin 1982bfcfaa77SLinus Torvalds #endif 1983bfcfaa77SLinus Torvalds 19842a18da7aSGeorge Spelvin /* 19852a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 19862a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 19872a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 19882a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 19892a18da7aSGeorge Spelvin * finds the delimiter after the name. 19902a18da7aSGeorge Spelvin */ 19918387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 1992bfcfaa77SLinus Torvalds { 19938387ff25SLinus Torvalds unsigned long a, x = 0, y = (unsigned long)salt; 1994bfcfaa77SLinus Torvalds 1995bfcfaa77SLinus Torvalds for (;;) { 1996fcfd2fbfSGeorge Spelvin if (!len) 1997fcfd2fbfSGeorge Spelvin goto done; 1998e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1999bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 2000bfcfaa77SLinus Torvalds break; 20012a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2002bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 2003bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 2004bfcfaa77SLinus Torvalds } 20052a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 2006bfcfaa77SLinus Torvalds done: 20072a18da7aSGeorge Spelvin return fold_hash(x, y); 2008bfcfaa77SLinus Torvalds } 2009bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 2010bfcfaa77SLinus Torvalds 2011fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 20128387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2013fcfd2fbfSGeorge Spelvin { 20148387ff25SLinus Torvalds unsigned long a = 0, x = 0, y = (unsigned long)salt; 20158387ff25SLinus Torvalds unsigned long adata, mask, len; 2016fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 2017fcfd2fbfSGeorge Spelvin 20188387ff25SLinus Torvalds len = 0; 20198387ff25SLinus Torvalds goto inside; 20208387ff25SLinus Torvalds 2021fcfd2fbfSGeorge Spelvin do { 20222a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2023fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 20248387ff25SLinus Torvalds inside: 2025fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 2026fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 2027fcfd2fbfSGeorge Spelvin 2028fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 2029fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 20302a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 2031fcfd2fbfSGeorge Spelvin 20322a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2033fcfd2fbfSGeorge Spelvin } 2034fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2035fcfd2fbfSGeorge Spelvin 2036bfcfaa77SLinus Torvalds /* 2037bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 2038d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 2039bfcfaa77SLinus Torvalds */ 20408387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2041bfcfaa77SLinus Torvalds { 20428387ff25SLinus Torvalds unsigned long a = 0, b, x = 0, y = (unsigned long)salt; 20438387ff25SLinus Torvalds unsigned long adata, bdata, mask, len; 204436126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 2045bfcfaa77SLinus Torvalds 20468387ff25SLinus Torvalds len = 0; 20478387ff25SLinus Torvalds goto inside; 20488387ff25SLinus Torvalds 2049bfcfaa77SLinus Torvalds do { 20502a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2051bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 20528387ff25SLinus Torvalds inside: 2053e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 205436126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 205536126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 2056bfcfaa77SLinus Torvalds 205736126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 205836126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 205936126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 20602a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 206136126f8fSLinus Torvalds 20622a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2063bfcfaa77SLinus Torvalds } 2064bfcfaa77SLinus Torvalds 20652a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 2066bfcfaa77SLinus Torvalds 2067fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 20688387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 20690145acc2SLinus Torvalds { 20708387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 20710145acc2SLinus Torvalds while (len--) 2072fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 20730145acc2SLinus Torvalds return end_name_hash(hash); 20740145acc2SLinus Torvalds } 2075ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 20760145acc2SLinus Torvalds 2077fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 20788387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2079fcfd2fbfSGeorge Spelvin { 20808387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2081fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 2082fcfd2fbfSGeorge Spelvin 2083fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 2084e0ab7af9SGeorge Spelvin while (c) { 2085fcfd2fbfSGeorge Spelvin len++; 2086fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 2087fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 2088e0ab7af9SGeorge Spelvin } 2089fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 2090fcfd2fbfSGeorge Spelvin } 2091f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2092fcfd2fbfSGeorge Spelvin 20933ddcd056SLinus Torvalds /* 2094200e9ef7SLinus Torvalds * We know there's a real path component here of at least 2095200e9ef7SLinus Torvalds * one character. 2096200e9ef7SLinus Torvalds */ 20978387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2098200e9ef7SLinus Torvalds { 20998387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2100200e9ef7SLinus Torvalds unsigned long len = 0, c; 2101200e9ef7SLinus Torvalds 2102200e9ef7SLinus Torvalds c = (unsigned char)*name; 2103200e9ef7SLinus Torvalds do { 2104200e9ef7SLinus Torvalds len++; 2105200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2106200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2107200e9ef7SLinus Torvalds } while (c && c != '/'); 2108d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2109200e9ef7SLinus Torvalds } 2110200e9ef7SLinus Torvalds 2111bfcfaa77SLinus Torvalds #endif 2112bfcfaa77SLinus Torvalds 2113200e9ef7SLinus Torvalds /* 21141da177e4SLinus Torvalds * Name resolution. 2115ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2116ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 21171da177e4SLinus Torvalds * 2118ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2119ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 21201da177e4SLinus Torvalds */ 21216de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 21221da177e4SLinus Torvalds { 2123d8d4611aSAl Viro int depth = 0; // depth <= nd->depth 21241da177e4SLinus Torvalds int err; 21251da177e4SLinus Torvalds 2126b4c03536SAl Viro nd->last_type = LAST_ROOT; 21279b5858e9SAl Viro if (IS_ERR(name)) 21289b5858e9SAl Viro return PTR_ERR(name); 21291da177e4SLinus Torvalds while (*name=='/') 21301da177e4SLinus Torvalds name++; 21311da177e4SLinus Torvalds if (!*name) 21329e18f10aSAl Viro return 0; 21331da177e4SLinus Torvalds 21341da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 21351da177e4SLinus Torvalds for(;;) { 213692d27016SAl Viro const char *link; 2137d6bb3e90SLinus Torvalds u64 hash_len; 2138fe479a58SAl Viro int type; 21391da177e4SLinus Torvalds 214052094c8aSAl Viro err = may_lookup(nd); 21411da177e4SLinus Torvalds if (err) 21423595e234SAl Viro return err; 21431da177e4SLinus Torvalds 21448387ff25SLinus Torvalds hash_len = hash_name(nd->path.dentry, name); 21451da177e4SLinus Torvalds 2146fe479a58SAl Viro type = LAST_NORM; 2147d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2148fe479a58SAl Viro case 2: 2149200e9ef7SLinus Torvalds if (name[1] == '.') { 2150fe479a58SAl Viro type = LAST_DOTDOT; 215116c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 215216c2cd71SAl Viro } 2153fe479a58SAl Viro break; 2154fe479a58SAl Viro case 1: 2155fe479a58SAl Viro type = LAST_DOT; 2156fe479a58SAl Viro } 21575a202bcdSAl Viro if (likely(type == LAST_NORM)) { 21585a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 215916c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 21605a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2161a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2162da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 21635a202bcdSAl Viro if (err < 0) 21643595e234SAl Viro return err; 2165d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2166d6bb3e90SLinus Torvalds name = this.name; 21675a202bcdSAl Viro } 21685a202bcdSAl Viro } 2169fe479a58SAl Viro 2170d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2171d6bb3e90SLinus Torvalds nd->last.name = name; 21725f4a6a69SAl Viro nd->last_type = type; 21735f4a6a69SAl Viro 2174d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2175d6bb3e90SLinus Torvalds if (!*name) 2176bdf6cbf1SAl Viro goto OK; 2177200e9ef7SLinus Torvalds /* 2178200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2179200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2180200e9ef7SLinus Torvalds */ 2181200e9ef7SLinus Torvalds do { 2182d6bb3e90SLinus Torvalds name++; 2183d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 21848620c238SAl Viro if (unlikely(!*name)) { 21858620c238SAl Viro OK: 2186d8d4611aSAl Viro /* pathname or trailing symlink, done */ 2187d8d4611aSAl Viro if (!depth) 21888620c238SAl Viro return 0; 21898620c238SAl Viro /* last component of nested symlink */ 2190d8d4611aSAl Viro name = nd->stack[--depth].name; 21918c4efe22SAl Viro link = walk_component(nd, 0); 21921c4ff1a8SAl Viro } else { 21931c4ff1a8SAl Viro /* not the last component */ 21948c4efe22SAl Viro link = walk_component(nd, WALK_MORE); 21958620c238SAl Viro } 219692d27016SAl Viro if (unlikely(link)) { 219792d27016SAl Viro if (IS_ERR(link)) 219892d27016SAl Viro return PTR_ERR(link); 219992d27016SAl Viro /* a symlink to follow */ 2200d8d4611aSAl Viro nd->stack[depth++].name = name; 220192d27016SAl Viro name = link; 22029e18f10aSAl Viro continue; 220348c8b0c5SAl Viro } 220497242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 220597242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 22064675ac39SAl Viro if (unlazy_walk(nd)) 220797242f99SAl Viro return -ECHILD; 220897242f99SAl Viro } 22093595e234SAl Viro return -ENOTDIR; 22105f4a6a69SAl Viro } 2211ce57dfc1SAl Viro } 221297242f99SAl Viro } 22131da177e4SLinus Torvalds 2214edc2b1daSAl Viro /* must be paired with terminate_walk() */ 2215c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 221631e6b01fSNick Piggin { 2217740a1678SAleksa Sarai int error; 2218c8a53ee5SAl Viro const char *s = nd->name->name; 221931e6b01fSNick Piggin 2220c0eb027eSLinus Torvalds if (!*s) 2221c0eb027eSLinus Torvalds flags &= ~LOOKUP_RCU; 2222edc2b1daSAl Viro if (flags & LOOKUP_RCU) 2223edc2b1daSAl Viro rcu_read_lock(); 2224c0eb027eSLinus Torvalds 2225980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 222631e6b01fSNick Piggin nd->depth = 0; 2227ab87f9a5SAleksa Sarai 2228ab87f9a5SAleksa Sarai nd->m_seq = __read_seqcount_begin(&mount_lock.seqcount); 2229ab87f9a5SAleksa Sarai nd->r_seq = __read_seqcount_begin(&rename_lock.seqcount); 2230ab87f9a5SAleksa Sarai smp_rmb(); 2231ab87f9a5SAleksa Sarai 22325b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2233b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2234b18825a7SDavid Howells struct inode *inode = root->d_inode; 223593893862SAl Viro if (*s && unlikely(!d_can_lookup(root))) 2236368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 22375b6ca027SAl Viro nd->path = nd->root; 22385b6ca027SAl Viro nd->inode = inode; 22395b6ca027SAl Viro if (flags & LOOKUP_RCU) { 2240ab87f9a5SAleksa Sarai nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22418f47a016SAl Viro nd->root_seq = nd->seq; 22425b6ca027SAl Viro } else { 22435b6ca027SAl Viro path_get(&nd->path); 22445b6ca027SAl Viro } 2245368ee9baSAl Viro return s; 22465b6ca027SAl Viro } 22475b6ca027SAl Viro 224831e6b01fSNick Piggin nd->root.mnt = NULL; 2249248fb5b9SAl Viro nd->path.mnt = NULL; 2250248fb5b9SAl Viro nd->path.dentry = NULL; 225131e6b01fSNick Piggin 22528db52c7eSAleksa Sarai /* Absolute pathname -- fetch the root (LOOKUP_IN_ROOT uses nd->dfd). */ 22538db52c7eSAleksa Sarai if (*s == '/' && !(flags & LOOKUP_IN_ROOT)) { 2254740a1678SAleksa Sarai error = nd_jump_root(nd); 2255740a1678SAleksa Sarai if (unlikely(error)) 2256740a1678SAleksa Sarai return ERR_PTR(error); 2257ef55d917SAl Viro return s; 22588db52c7eSAleksa Sarai } 22598db52c7eSAleksa Sarai 22608db52c7eSAleksa Sarai /* Relative pathname -- get the starting-point it is relative to. */ 22618db52c7eSAleksa Sarai if (nd->dfd == AT_FDCWD) { 2262e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 226331e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2264c28cc364SNick Piggin unsigned seq; 226531e6b01fSNick Piggin 2266c28cc364SNick Piggin do { 2267c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 226831e6b01fSNick Piggin nd->path = fs->pwd; 2269ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2270c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2271c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2272e41f7d4eSAl Viro } else { 2273e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2274ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2275e41f7d4eSAl Viro } 227631e6b01fSNick Piggin } else { 2277582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2278c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 227931e6b01fSNick Piggin struct dentry *dentry; 228031e6b01fSNick Piggin 22812903ff01SAl Viro if (!f.file) 2282368ee9baSAl Viro return ERR_PTR(-EBADF); 228331e6b01fSNick Piggin 22842903ff01SAl Viro dentry = f.file->f_path.dentry; 228531e6b01fSNick Piggin 2286edc2b1daSAl Viro if (*s && unlikely(!d_can_lookup(dentry))) { 22872903ff01SAl Viro fdput(f); 2288368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2289f52e0c11SAl Viro } 22902903ff01SAl Viro 22912903ff01SAl Viro nd->path = f.file->f_path; 2292e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 229334a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 229434a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22955590ff0dSUlrich Drepper } else { 22962903ff01SAl Viro path_get(&nd->path); 229734a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 22981da177e4SLinus Torvalds } 229934a26b99SAl Viro fdput(f); 2300e41f7d4eSAl Viro } 23018db52c7eSAleksa Sarai 2302adb21d2bSAleksa Sarai /* For scoped-lookups we need to set the root to the dirfd as well. */ 2303adb21d2bSAleksa Sarai if (flags & LOOKUP_IS_SCOPED) { 2304adb21d2bSAleksa Sarai nd->root = nd->path; 2305adb21d2bSAleksa Sarai if (flags & LOOKUP_RCU) { 2306adb21d2bSAleksa Sarai nd->root_seq = nd->seq; 2307adb21d2bSAleksa Sarai } else { 2308adb21d2bSAleksa Sarai path_get(&nd->root); 2309adb21d2bSAleksa Sarai nd->flags |= LOOKUP_ROOT_GRABBED; 2310adb21d2bSAleksa Sarai } 2311adb21d2bSAleksa Sarai } 2312adb21d2bSAleksa Sarai return s; 23139b4a9b14SAl Viro } 23149b4a9b14SAl Viro 23151ccac622SAl Viro static inline const char *lookup_last(struct nameidata *nd) 231695fa25d9SAl Viro { 231792d27016SAl Viro const char *link; 2318bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2319bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2320bd92d7feSAl Viro 2321bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 23228c4efe22SAl Viro link = walk_component(nd, WALK_TRAILING); 232392d27016SAl Viro if (link) { 23241ccac622SAl Viro nd->flags |= LOOKUP_PARENT; 23251ccac622SAl Viro } 232692d27016SAl Viro return link; 2327bd92d7feSAl Viro } 2328bd92d7feSAl Viro 23294f757f3cSAl Viro static int handle_lookup_down(struct nameidata *nd) 23304f757f3cSAl Viro { 2331c153007bSAl Viro if (!(nd->flags & LOOKUP_RCU)) 2332db3c9adeSAl Viro dget(nd->path.dentry); 2333b0417d2cSAl Viro return PTR_ERR(step_into(nd, WALK_NOFOLLOW, 2334b0417d2cSAl Viro nd->path.dentry, nd->inode, nd->seq)); 23354f757f3cSAl Viro } 23364f757f3cSAl Viro 23379b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2338c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 23399b4a9b14SAl Viro { 2340c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2341bd92d7feSAl Viro int err; 234231e6b01fSNick Piggin 23439b5858e9SAl Viro if (unlikely(flags & LOOKUP_DOWN) && !IS_ERR(s)) { 23444f757f3cSAl Viro err = handle_lookup_down(nd); 23455f336e72SAl Viro if (unlikely(err < 0)) 23465f336e72SAl Viro s = ERR_PTR(err); 23474f757f3cSAl Viro } 23484f757f3cSAl Viro 23491ccac622SAl Viro while (!(err = link_path_walk(s, nd)) && 23501ccac622SAl Viro (s = lookup_last(nd)) != NULL) 23511ccac622SAl Viro ; 23529f1fafeeSAl Viro if (!err) 23539f1fafeeSAl Viro err = complete_walk(nd); 2354bd92d7feSAl Viro 2355deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2356deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2357bd23a539SAl Viro err = -ENOTDIR; 2358161aff1dSAl Viro if (!err && unlikely(nd->flags & LOOKUP_MOUNTPOINT)) { 2359161aff1dSAl Viro err = handle_lookup_down(nd); 2360161aff1dSAl Viro nd->flags &= ~LOOKUP_JUMPED; // no d_weak_revalidate(), please... 2361161aff1dSAl Viro } 2362625b6d10SAl Viro if (!err) { 2363625b6d10SAl Viro *path = nd->path; 2364625b6d10SAl Viro nd->path.mnt = NULL; 2365625b6d10SAl Viro nd->path.dentry = NULL; 2366625b6d10SAl Viro } 2367deb106c6SAl Viro terminate_walk(nd); 2368bd92d7feSAl Viro return err; 236931e6b01fSNick Piggin } 237031e6b01fSNick Piggin 237131d921c7SDavid Howells int filename_lookup(int dfd, struct filename *name, unsigned flags, 23729ad1aaa6SAl Viro struct path *path, struct path *root) 2373873f1eedSJeff Layton { 2374894bc8c4SAl Viro int retval; 23759883d185SAl Viro struct nameidata nd; 2376abc9f5beSAl Viro if (IS_ERR(name)) 2377abc9f5beSAl Viro return PTR_ERR(name); 23789ad1aaa6SAl Viro if (unlikely(root)) { 23799ad1aaa6SAl Viro nd.root = *root; 23809ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 23819ad1aaa6SAl Viro } 23829883d185SAl Viro set_nameidata(&nd, dfd, name); 2383c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2384873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2385c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2386873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2387c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2388873f1eedSJeff Layton 2389873f1eedSJeff Layton if (likely(!retval)) 2390161aff1dSAl Viro audit_inode(name, path->dentry, 2391161aff1dSAl Viro flags & LOOKUP_MOUNTPOINT ? AUDIT_INODE_NOEVAL : 0); 23929883d185SAl Viro restore_nameidata(); 2393e4bd1c1aSAl Viro putname(name); 2394873f1eedSJeff Layton return retval; 2395873f1eedSJeff Layton } 2396873f1eedSJeff Layton 23978bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2398c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2399391172c4SAl Viro struct path *parent) 24008bcb77faSAl Viro { 2401c8a53ee5SAl Viro const char *s = path_init(nd, flags); 24029b5858e9SAl Viro int err = link_path_walk(s, nd); 24038bcb77faSAl Viro if (!err) 24048bcb77faSAl Viro err = complete_walk(nd); 2405391172c4SAl Viro if (!err) { 2406391172c4SAl Viro *parent = nd->path; 2407391172c4SAl Viro nd->path.mnt = NULL; 2408391172c4SAl Viro nd->path.dentry = NULL; 2409391172c4SAl Viro } 2410deb106c6SAl Viro terminate_walk(nd); 24118bcb77faSAl Viro return err; 24128bcb77faSAl Viro } 24138bcb77faSAl Viro 24145c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2415391172c4SAl Viro unsigned int flags, struct path *parent, 2416391172c4SAl Viro struct qstr *last, int *type) 24178bcb77faSAl Viro { 24188bcb77faSAl Viro int retval; 24199883d185SAl Viro struct nameidata nd; 24208bcb77faSAl Viro 24215c31b6ceSAl Viro if (IS_ERR(name)) 24225c31b6ceSAl Viro return name; 24239883d185SAl Viro set_nameidata(&nd, dfd, name); 2424c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 24258bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2426c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 24278bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2428c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2429391172c4SAl Viro if (likely(!retval)) { 2430391172c4SAl Viro *last = nd.last; 2431391172c4SAl Viro *type = nd.last_type; 2432c9b07eabSAl Viro audit_inode(name, parent->dentry, AUDIT_INODE_PARENT); 24335c31b6ceSAl Viro } else { 24345c31b6ceSAl Viro putname(name); 24355c31b6ceSAl Viro name = ERR_PTR(retval); 2436391172c4SAl Viro } 24379883d185SAl Viro restore_nameidata(); 24385c31b6ceSAl Viro return name; 24398bcb77faSAl Viro } 24408bcb77faSAl Viro 244179714f72SAl Viro /* does lookup, returns the object with parent locked */ 244279714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 24435590ff0dSUlrich Drepper { 24445c31b6ceSAl Viro struct filename *filename; 24455c31b6ceSAl Viro struct dentry *d; 2446391172c4SAl Viro struct qstr last; 2447391172c4SAl Viro int type; 244851689104SPaul Moore 24495c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 24505c31b6ceSAl Viro &last, &type); 245151689104SPaul Moore if (IS_ERR(filename)) 245251689104SPaul Moore return ERR_CAST(filename); 24535c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2454391172c4SAl Viro path_put(path); 24555c31b6ceSAl Viro putname(filename); 24565c31b6ceSAl Viro return ERR_PTR(-EINVAL); 245779714f72SAl Viro } 24585955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2459391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 246079714f72SAl Viro if (IS_ERR(d)) { 24615955102cSAl Viro inode_unlock(path->dentry->d_inode); 2462391172c4SAl Viro path_put(path); 246379714f72SAl Viro } 246451689104SPaul Moore putname(filename); 246579714f72SAl Viro return d; 24665590ff0dSUlrich Drepper } 24675590ff0dSUlrich Drepper 2468d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2469d1811465SAl Viro { 2470abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2471abc9f5beSAl Viro flags, path, NULL); 2472d1811465SAl Viro } 24734d359507SAl Viro EXPORT_SYMBOL(kern_path); 2474d1811465SAl Viro 247516f18200SJosef 'Jeff' Sipek /** 247616f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 247716f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 247816f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 247916f18200SJosef 'Jeff' Sipek * @name: pointer to file name 248016f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2481e0a01249SAl Viro * @path: pointer to struct path to fill 248216f18200SJosef 'Jeff' Sipek */ 248316f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 248416f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2485e0a01249SAl Viro struct path *path) 248616f18200SJosef 'Jeff' Sipek { 24879ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 24889ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2489abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2490abc9f5beSAl Viro flags , path, &root); 249116f18200SJosef 'Jeff' Sipek } 24924d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 249316f18200SJosef 'Jeff' Sipek 24943c95f0dcSAl Viro static int lookup_one_len_common(const char *name, struct dentry *base, 24953c95f0dcSAl Viro int len, struct qstr *this) 24963c95f0dcSAl Viro { 24973c95f0dcSAl Viro this->name = name; 24983c95f0dcSAl Viro this->len = len; 24993c95f0dcSAl Viro this->hash = full_name_hash(base, name, len); 25003c95f0dcSAl Viro if (!len) 25013c95f0dcSAl Viro return -EACCES; 25023c95f0dcSAl Viro 25033c95f0dcSAl Viro if (unlikely(name[0] == '.')) { 25043c95f0dcSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 25053c95f0dcSAl Viro return -EACCES; 25063c95f0dcSAl Viro } 25073c95f0dcSAl Viro 25083c95f0dcSAl Viro while (len--) { 25093c95f0dcSAl Viro unsigned int c = *(const unsigned char *)name++; 25103c95f0dcSAl Viro if (c == '/' || c == '\0') 25113c95f0dcSAl Viro return -EACCES; 25123c95f0dcSAl Viro } 25133c95f0dcSAl Viro /* 25143c95f0dcSAl Viro * See if the low-level filesystem might want 25153c95f0dcSAl Viro * to use its own hash.. 25163c95f0dcSAl Viro */ 25173c95f0dcSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 25183c95f0dcSAl Viro int err = base->d_op->d_hash(base, this); 25193c95f0dcSAl Viro if (err < 0) 25203c95f0dcSAl Viro return err; 25213c95f0dcSAl Viro } 25223c95f0dcSAl Viro 25233c95f0dcSAl Viro return inode_permission(base->d_inode, MAY_EXEC); 25243c95f0dcSAl Viro } 25253c95f0dcSAl Viro 2526eead1911SChristoph Hellwig /** 25270da0b7fdSDavid Howells * try_lookup_one_len - filesystem helper to lookup single pathname component 25280da0b7fdSDavid Howells * @name: pathname component to lookup 25290da0b7fdSDavid Howells * @base: base directory to lookup from 25300da0b7fdSDavid Howells * @len: maximum length @len should be interpreted to 25310da0b7fdSDavid Howells * 25320da0b7fdSDavid Howells * Look up a dentry by name in the dcache, returning NULL if it does not 25330da0b7fdSDavid Howells * currently exist. The function does not try to create a dentry. 25340da0b7fdSDavid Howells * 25350da0b7fdSDavid Howells * Note that this routine is purely a helper for filesystem usage and should 25360da0b7fdSDavid Howells * not be called by generic code. 25370da0b7fdSDavid Howells * 25380da0b7fdSDavid Howells * The caller must hold base->i_mutex. 25390da0b7fdSDavid Howells */ 25400da0b7fdSDavid Howells struct dentry *try_lookup_one_len(const char *name, struct dentry *base, int len) 25410da0b7fdSDavid Howells { 25420da0b7fdSDavid Howells struct qstr this; 25430da0b7fdSDavid Howells int err; 25440da0b7fdSDavid Howells 25450da0b7fdSDavid Howells WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 25460da0b7fdSDavid Howells 25470da0b7fdSDavid Howells err = lookup_one_len_common(name, base, len, &this); 25480da0b7fdSDavid Howells if (err) 25490da0b7fdSDavid Howells return ERR_PTR(err); 25500da0b7fdSDavid Howells 25510da0b7fdSDavid Howells return lookup_dcache(&this, base, 0); 25520da0b7fdSDavid Howells } 25530da0b7fdSDavid Howells EXPORT_SYMBOL(try_lookup_one_len); 25540da0b7fdSDavid Howells 25550da0b7fdSDavid Howells /** 2556a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2557eead1911SChristoph Hellwig * @name: pathname component to lookup 2558eead1911SChristoph Hellwig * @base: base directory to lookup from 2559eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2560eead1911SChristoph Hellwig * 2561a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 25629e7543e9SAl Viro * not be called by generic code. 2563bbddca8eSNeilBrown * 2564bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2565eead1911SChristoph Hellwig */ 2566057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2567057f6c01SJames Morris { 25688613a209SAl Viro struct dentry *dentry; 2569057f6c01SJames Morris struct qstr this; 2570cda309deSMiklos Szeredi int err; 2571057f6c01SJames Morris 25725955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 25732f9092e1SDavid Woodhouse 25743c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2575cda309deSMiklos Szeredi if (err) 2576cda309deSMiklos Szeredi return ERR_PTR(err); 2577cda309deSMiklos Szeredi 25788613a209SAl Viro dentry = lookup_dcache(&this, base, 0); 25798613a209SAl Viro return dentry ? dentry : __lookup_slow(&this, base, 0); 2580057f6c01SJames Morris } 25814d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2582057f6c01SJames Morris 2583bbddca8eSNeilBrown /** 2584bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2585bbddca8eSNeilBrown * @name: pathname component to lookup 2586bbddca8eSNeilBrown * @base: base directory to lookup from 2587bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2588bbddca8eSNeilBrown * 2589bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2590bbddca8eSNeilBrown * not be called by generic code. 2591bbddca8eSNeilBrown * 2592bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2593bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2594bbddca8eSNeilBrown */ 2595bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2596bbddca8eSNeilBrown struct dentry *base, int len) 2597bbddca8eSNeilBrown { 2598bbddca8eSNeilBrown struct qstr this; 2599bbddca8eSNeilBrown int err; 260020d00ee8SLinus Torvalds struct dentry *ret; 2601bbddca8eSNeilBrown 26023c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2603bbddca8eSNeilBrown if (err) 2604bbddca8eSNeilBrown return ERR_PTR(err); 2605bbddca8eSNeilBrown 260620d00ee8SLinus Torvalds ret = lookup_dcache(&this, base, 0); 260720d00ee8SLinus Torvalds if (!ret) 260820d00ee8SLinus Torvalds ret = lookup_slow(&this, base, 0); 260920d00ee8SLinus Torvalds return ret; 2610bbddca8eSNeilBrown } 2611bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2612bbddca8eSNeilBrown 26136c2d4798SAl Viro /* 26146c2d4798SAl Viro * Like lookup_one_len_unlocked(), except that it yields ERR_PTR(-ENOENT) 26156c2d4798SAl Viro * on negatives. Returns known positive or ERR_PTR(); that's what 26166c2d4798SAl Viro * most of the users want. Note that pinned negative with unlocked parent 26176c2d4798SAl Viro * _can_ become positive at any time, so callers of lookup_one_len_unlocked() 26186c2d4798SAl Viro * need to be very careful; pinned positives have ->d_inode stable, so 26196c2d4798SAl Viro * this one avoids such problems. 26206c2d4798SAl Viro */ 26216c2d4798SAl Viro struct dentry *lookup_positive_unlocked(const char *name, 26226c2d4798SAl Viro struct dentry *base, int len) 26236c2d4798SAl Viro { 26246c2d4798SAl Viro struct dentry *ret = lookup_one_len_unlocked(name, base, len); 26252fa6b1e0SAl Viro if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) { 26266c2d4798SAl Viro dput(ret); 26276c2d4798SAl Viro ret = ERR_PTR(-ENOENT); 26286c2d4798SAl Viro } 26296c2d4798SAl Viro return ret; 26306c2d4798SAl Viro } 26316c2d4798SAl Viro EXPORT_SYMBOL(lookup_positive_unlocked); 26326c2d4798SAl Viro 2633eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2634eedf265aSEric W. Biederman int path_pts(struct path *path) 2635eedf265aSEric W. Biederman { 2636eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2637eedf265aSEric W. Biederman * the input path. 2638eedf265aSEric W. Biederman */ 2639eedf265aSEric W. Biederman struct dentry *child, *parent; 2640eedf265aSEric W. Biederman struct qstr this; 2641eedf265aSEric W. Biederman int ret; 2642eedf265aSEric W. Biederman 2643eedf265aSEric W. Biederman ret = path_parent_directory(path); 2644eedf265aSEric W. Biederman if (ret) 2645eedf265aSEric W. Biederman return ret; 2646eedf265aSEric W. Biederman 2647eedf265aSEric W. Biederman parent = path->dentry; 2648eedf265aSEric W. Biederman this.name = "pts"; 2649eedf265aSEric W. Biederman this.len = 3; 2650eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2651eedf265aSEric W. Biederman if (!child) 2652eedf265aSEric W. Biederman return -ENOENT; 2653eedf265aSEric W. Biederman 2654eedf265aSEric W. Biederman path->dentry = child; 2655eedf265aSEric W. Biederman dput(parent); 2656eedf265aSEric W. Biederman follow_mount(path); 2657eedf265aSEric W. Biederman return 0; 2658eedf265aSEric W. Biederman } 2659eedf265aSEric W. Biederman #endif 2660eedf265aSEric W. Biederman 26611fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 26621fa1e7f6SAndy Whitcroft struct path *path, int *empty) 26631da177e4SLinus Torvalds { 2664abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2665abc9f5beSAl Viro flags, path, NULL); 26661da177e4SLinus Torvalds } 2667b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 26681fa1e7f6SAndy Whitcroft 2669cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 26701da177e4SLinus Torvalds { 26718e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2672da9592edSDavid Howells 26738e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 26741da177e4SLinus Torvalds return 0; 26758e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 26761da177e4SLinus Torvalds return 0; 267723adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 26781da177e4SLinus Torvalds } 2679cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 26801da177e4SLinus Torvalds 26811da177e4SLinus Torvalds /* 26821da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 26831da177e4SLinus Torvalds * whether the type of victim is right. 26841da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 26851da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 26861da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 26871da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 26881da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 26891da177e4SLinus Torvalds * a. be owner of dir, or 26901da177e4SLinus Torvalds * b. be owner of victim, or 26911da177e4SLinus Torvalds * c. have CAP_FOWNER capability 26921da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 26931da177e4SLinus Torvalds * links pointing to it. 26940bd23d09SEric W. Biederman * 7. If the victim has an unknown uid or gid we can't change the inode. 26950bd23d09SEric W. Biederman * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. 26960bd23d09SEric W. Biederman * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. 26970bd23d09SEric W. Biederman * 10. We can't remove a root or mountpoint. 26980bd23d09SEric W. Biederman * 11. We don't allow removal of NFS sillyrenamed files; it's handled by 26991da177e4SLinus Torvalds * nfs_async_unlink(). 27001da177e4SLinus Torvalds */ 2701b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 27021da177e4SLinus Torvalds { 270363afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 27041da177e4SLinus Torvalds int error; 27051da177e4SLinus Torvalds 2706b18825a7SDavid Howells if (d_is_negative(victim)) 27071da177e4SLinus Torvalds return -ENOENT; 2708b18825a7SDavid Howells BUG_ON(!inode); 27091da177e4SLinus Torvalds 27101da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 2711593d1ce8SEric W. Biederman 2712593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 2713593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 2714593d1ce8SEric W. Biederman return -EOVERFLOW; 2715593d1ce8SEric W. Biederman 27164fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 27171da177e4SLinus Torvalds 2718f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 27191da177e4SLinus Torvalds if (error) 27201da177e4SLinus Torvalds return error; 27211da177e4SLinus Torvalds if (IS_APPEND(dir)) 27221da177e4SLinus Torvalds return -EPERM; 2723b18825a7SDavid Howells 2724b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 27250bd23d09SEric W. Biederman IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) 27261da177e4SLinus Torvalds return -EPERM; 27271da177e4SLinus Torvalds if (isdir) { 272844b1d530SMiklos Szeredi if (!d_is_dir(victim)) 27291da177e4SLinus Torvalds return -ENOTDIR; 27301da177e4SLinus Torvalds if (IS_ROOT(victim)) 27311da177e4SLinus Torvalds return -EBUSY; 273244b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 27331da177e4SLinus Torvalds return -EISDIR; 27341da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27351da177e4SLinus Torvalds return -ENOENT; 27361da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 27371da177e4SLinus Torvalds return -EBUSY; 27381da177e4SLinus Torvalds return 0; 27391da177e4SLinus Torvalds } 27401da177e4SLinus Torvalds 27411da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 27421da177e4SLinus Torvalds * dir. 27431da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 27441da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 27451da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 2746036d5236SEric W. Biederman * 3. We can't do it if the fs can't represent the fsuid or fsgid. 2747036d5236SEric W. Biederman * 4. We should have write and exec permissions on dir 2748036d5236SEric W. Biederman * 5. We can't do it if dir is immutable (done in permission()) 27491da177e4SLinus Torvalds */ 2750a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 27511da177e4SLinus Torvalds { 2752036d5236SEric W. Biederman struct user_namespace *s_user_ns; 275314e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 27541da177e4SLinus Torvalds if (child->d_inode) 27551da177e4SLinus Torvalds return -EEXIST; 27561da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27571da177e4SLinus Torvalds return -ENOENT; 2758036d5236SEric W. Biederman s_user_ns = dir->i_sb->s_user_ns; 2759036d5236SEric W. Biederman if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 2760036d5236SEric W. Biederman !kgid_has_mapping(s_user_ns, current_fsgid())) 2761036d5236SEric W. Biederman return -EOVERFLOW; 2762f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 27631da177e4SLinus Torvalds } 27641da177e4SLinus Torvalds 27651da177e4SLinus Torvalds /* 27661da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 27671da177e4SLinus Torvalds */ 27681da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 27691da177e4SLinus Torvalds { 27701da177e4SLinus Torvalds struct dentry *p; 27711da177e4SLinus Torvalds 27721da177e4SLinus Torvalds if (p1 == p2) { 27735955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27741da177e4SLinus Torvalds return NULL; 27751da177e4SLinus Torvalds } 27761da177e4SLinus Torvalds 2777fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 27781da177e4SLinus Torvalds 2779e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2780e2761a11SOGAWA Hirofumi if (p) { 27815955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 27825955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 27831da177e4SLinus Torvalds return p; 27841da177e4SLinus Torvalds } 27851da177e4SLinus Torvalds 2786e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2787e2761a11SOGAWA Hirofumi if (p) { 27885955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27895955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 27901da177e4SLinus Torvalds return p; 27911da177e4SLinus Torvalds } 27921da177e4SLinus Torvalds 27935955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27945955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 27951da177e4SLinus Torvalds return NULL; 27961da177e4SLinus Torvalds } 27974d359507SAl Viro EXPORT_SYMBOL(lock_rename); 27981da177e4SLinus Torvalds 27991da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 28001da177e4SLinus Torvalds { 28015955102cSAl Viro inode_unlock(p1->d_inode); 28021da177e4SLinus Torvalds if (p1 != p2) { 28035955102cSAl Viro inode_unlock(p2->d_inode); 2804fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 28051da177e4SLinus Torvalds } 28061da177e4SLinus Torvalds } 28074d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 28081da177e4SLinus Torvalds 28094acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2810312b63fbSAl Viro bool want_excl) 28111da177e4SLinus Torvalds { 2812a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28131da177e4SLinus Torvalds if (error) 28141da177e4SLinus Torvalds return error; 28151da177e4SLinus Torvalds 2816acfa4380SAl Viro if (!dir->i_op->create) 28171da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 28181da177e4SLinus Torvalds mode &= S_IALLUGO; 28191da177e4SLinus Torvalds mode |= S_IFREG; 28201da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 28211da177e4SLinus Torvalds if (error) 28221da177e4SLinus Torvalds return error; 2823312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2824a74574aaSStephen Smalley if (!error) 2825f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28261da177e4SLinus Torvalds return error; 28271da177e4SLinus Torvalds } 28284d359507SAl Viro EXPORT_SYMBOL(vfs_create); 28291da177e4SLinus Torvalds 28308e6c848eSAl Viro int vfs_mkobj(struct dentry *dentry, umode_t mode, 28318e6c848eSAl Viro int (*f)(struct dentry *, umode_t, void *), 28328e6c848eSAl Viro void *arg) 28338e6c848eSAl Viro { 28348e6c848eSAl Viro struct inode *dir = dentry->d_parent->d_inode; 28358e6c848eSAl Viro int error = may_create(dir, dentry); 28368e6c848eSAl Viro if (error) 28378e6c848eSAl Viro return error; 28388e6c848eSAl Viro 28398e6c848eSAl Viro mode &= S_IALLUGO; 28408e6c848eSAl Viro mode |= S_IFREG; 28418e6c848eSAl Viro error = security_inode_create(dir, dentry, mode); 28428e6c848eSAl Viro if (error) 28438e6c848eSAl Viro return error; 28448e6c848eSAl Viro error = f(dentry, mode, arg); 28458e6c848eSAl Viro if (!error) 28468e6c848eSAl Viro fsnotify_create(dir, dentry); 28478e6c848eSAl Viro return error; 28488e6c848eSAl Viro } 28498e6c848eSAl Viro EXPORT_SYMBOL(vfs_mkobj); 28508e6c848eSAl Viro 2851a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 2852a2982cc9SEric W. Biederman { 2853a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 2854a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 2855a2982cc9SEric W. Biederman } 2856a2982cc9SEric W. Biederman 2857f0bb5aafSAl Viro static int may_open(const struct path *path, int acc_mode, int flag) 28581da177e4SLinus Torvalds { 28593fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 28601da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 28611da177e4SLinus Torvalds int error; 28621da177e4SLinus Torvalds 28631da177e4SLinus Torvalds if (!inode) 28641da177e4SLinus Torvalds return -ENOENT; 28651da177e4SLinus Torvalds 2866c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2867c8fe8f30SChristoph Hellwig case S_IFLNK: 28681da177e4SLinus Torvalds return -ELOOP; 2869c8fe8f30SChristoph Hellwig case S_IFDIR: 2870c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 28711da177e4SLinus Torvalds return -EISDIR; 2872c8fe8f30SChristoph Hellwig break; 2873c8fe8f30SChristoph Hellwig case S_IFBLK: 2874c8fe8f30SChristoph Hellwig case S_IFCHR: 2875a2982cc9SEric W. Biederman if (!may_open_dev(path)) 28761da177e4SLinus Torvalds return -EACCES; 2877c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2878c8fe8f30SChristoph Hellwig case S_IFIFO: 2879c8fe8f30SChristoph Hellwig case S_IFSOCK: 28801da177e4SLinus Torvalds flag &= ~O_TRUNC; 2881c8fe8f30SChristoph Hellwig break; 28824a3fd211SDave Hansen } 2883b41572e9SDave Hansen 288462fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2885b41572e9SDave Hansen if (error) 2886b41572e9SDave Hansen return error; 28876146f0d5SMimi Zohar 28881da177e4SLinus Torvalds /* 28891da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 28901da177e4SLinus Torvalds */ 28911da177e4SLinus Torvalds if (IS_APPEND(inode)) { 28928737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 28937715b521SAl Viro return -EPERM; 28941da177e4SLinus Torvalds if (flag & O_TRUNC) 28957715b521SAl Viro return -EPERM; 28961da177e4SLinus Torvalds } 28971da177e4SLinus Torvalds 28981da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 28992e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 29007715b521SAl Viro return -EPERM; 29011da177e4SLinus Torvalds 2902f3c7691eSJ. Bruce Fields return 0; 29037715b521SAl Viro } 29047715b521SAl Viro 2905e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 29067715b521SAl Viro { 2907f0bb5aafSAl Viro const struct path *path = &filp->f_path; 29087715b521SAl Viro struct inode *inode = path->dentry->d_inode; 29097715b521SAl Viro int error = get_write_access(inode); 29101da177e4SLinus Torvalds if (error) 29117715b521SAl Viro return error; 29121da177e4SLinus Torvalds /* 29131da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 29141da177e4SLinus Torvalds */ 2915d7a06983SJeff Layton error = locks_verify_locked(filp); 2916be6d3e56SKentaro Takeda if (!error) 2917ea0d3ab2STetsuo Handa error = security_path_truncate(path); 29181da177e4SLinus Torvalds if (!error) { 29197715b521SAl Viro error = do_truncate(path->dentry, 0, 2920d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2921e1181ee6SJeff Layton filp); 29221da177e4SLinus Torvalds } 29231da177e4SLinus Torvalds put_write_access(inode); 2924acd0c935SMimi Zohar return error; 29251da177e4SLinus Torvalds } 29261da177e4SLinus Torvalds 2927d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2928d57999e1SDave Hansen { 29298a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 29308a5e929dSAl Viro flag--; 2931d57999e1SDave Hansen return flag; 2932d57999e1SDave Hansen } 2933d57999e1SDave Hansen 2934d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 2935d18e9008SMiklos Szeredi { 29361328c727SSeth Forshee struct user_namespace *s_user_ns; 2937d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2938d18e9008SMiklos Szeredi if (error) 2939d18e9008SMiklos Szeredi return error; 2940d18e9008SMiklos Szeredi 29411328c727SSeth Forshee s_user_ns = dir->dentry->d_sb->s_user_ns; 29421328c727SSeth Forshee if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 29431328c727SSeth Forshee !kgid_has_mapping(s_user_ns, current_fsgid())) 29441328c727SSeth Forshee return -EOVERFLOW; 29451328c727SSeth Forshee 2946d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2947d18e9008SMiklos Szeredi if (error) 2948d18e9008SMiklos Szeredi return error; 2949d18e9008SMiklos Szeredi 2950d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2951d18e9008SMiklos Szeredi } 2952d18e9008SMiklos Szeredi 29531acf0af9SDavid Howells /* 29541acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 29551acf0af9SDavid Howells * dentry. 29561acf0af9SDavid Howells * 29571acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 29581acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 29591acf0af9SDavid Howells * 296000a07c15SAl Viro * If the file was looked up only or didn't need creating, FMODE_OPENED won't 296100a07c15SAl Viro * be set. The caller will need to perform the open themselves. @path will 296200a07c15SAl Viro * have been updated to point to the new dentry. This may be negative. 29631acf0af9SDavid Howells * 29641acf0af9SDavid Howells * Returns an error code otherwise. 29651acf0af9SDavid Howells */ 2966239eb983SAl Viro static struct dentry *atomic_open(struct nameidata *nd, struct dentry *dentry, 2967239eb983SAl Viro struct file *file, 2968015c3bbcSMiklos Szeredi const struct open_flags *op, 29693ec2eef1SAl Viro int open_flag, umode_t mode) 2970d18e9008SMiklos Szeredi { 2971d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2972d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2973d18e9008SMiklos Szeredi int error; 2974d18e9008SMiklos Szeredi 2975384f26e2SAl Viro if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ 2976d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2977d18e9008SMiklos Szeredi 2978d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2979d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2980d18e9008SMiklos Szeredi 298130d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 298230d90494SAl Viro file->f_path.mnt = nd->path.mnt; 29830fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 298444907d79SAl Viro open_to_namei_flags(open_flag), mode); 29856fbd0714SAl Viro d_lookup_done(dentry); 2986384f26e2SAl Viro if (!error) { 298764e1ac4dSAl Viro if (file->f_mode & FMODE_OPENED) { 2988d18e9008SMiklos Szeredi /* 2989384f26e2SAl Viro * We didn't have the inode before the open, so check open 2990384f26e2SAl Viro * permission here. 2991d18e9008SMiklos Szeredi */ 2992384f26e2SAl Viro int acc_mode = op->acc_mode; 299373a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) { 299403da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 299503da633aSAl Viro fsnotify_create(dir, dentry); 299662fb4a15SAl Viro acc_mode = 0; 299703da633aSAl Viro } 29982675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 2999384f26e2SAl Viro if (WARN_ON(error > 0)) 3000384f26e2SAl Viro error = -EINVAL; 300164e1ac4dSAl Viro } else if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 3002d18e9008SMiklos Szeredi error = -EIO; 3003384f26e2SAl Viro } else { 3004d18e9008SMiklos Szeredi if (file->f_path.dentry) { 3005d18e9008SMiklos Szeredi dput(dentry); 3006d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 300710c64ceaSAl Viro } 300873a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) 3009d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 3010239eb983SAl Viro if (unlikely(d_is_negative(dentry))) 3011a01e718fSAl Viro error = -ENOENT; 3012d18e9008SMiklos Szeredi } 3013d18e9008SMiklos Szeredi } 3014239eb983SAl Viro if (error) { 3015d18e9008SMiklos Szeredi dput(dentry); 3016239eb983SAl Viro dentry = ERR_PTR(error); 3017239eb983SAl Viro } 3018239eb983SAl Viro return dentry; 3019d18e9008SMiklos Szeredi } 3020d18e9008SMiklos Szeredi 302131e6b01fSNick Piggin /* 30221acf0af9SDavid Howells * Look up and maybe create and open the last component. 3023d58ffd35SMiklos Szeredi * 302400a07c15SAl Viro * Must be called with parent locked (exclusive in O_CREAT case). 3025d58ffd35SMiklos Szeredi * 302600a07c15SAl Viro * Returns 0 on success, that is, if 302700a07c15SAl Viro * the file was successfully atomically created (if necessary) and opened, or 302800a07c15SAl Viro * the file was not completely opened at this time, though lookups and 302900a07c15SAl Viro * creations were performed. 303000a07c15SAl Viro * These case are distinguished by presence of FMODE_OPENED on file->f_mode. 303100a07c15SAl Viro * In the latter case dentry returned in @path might be negative if O_CREAT 303200a07c15SAl Viro * hadn't been specified. 30331acf0af9SDavid Howells * 303400a07c15SAl Viro * An error code is returned on failure. 3035d58ffd35SMiklos Szeredi */ 3036da5ebf5aSAl Viro static struct dentry *lookup_open(struct nameidata *nd, struct file *file, 3037d58ffd35SMiklos Szeredi const struct open_flags *op, 30383ec2eef1SAl Viro bool got_write) 3039d58ffd35SMiklos Szeredi { 3040d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 304154ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 30421643b43fSAl Viro int open_flag = op->open_flag; 3043d58ffd35SMiklos Szeredi struct dentry *dentry; 30441643b43fSAl Viro int error, create_error = 0; 30451643b43fSAl Viro umode_t mode = op->mode; 30466fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3047d58ffd35SMiklos Szeredi 3048ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3049da5ebf5aSAl Viro return ERR_PTR(-ENOENT); 3050d58ffd35SMiklos Szeredi 305173a09dd9SAl Viro file->f_mode &= ~FMODE_CREATED; 30526fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 30536fbd0714SAl Viro for (;;) { 30546fbd0714SAl Viro if (!dentry) { 30556fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3056d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 3057da5ebf5aSAl Viro return dentry; 30586fbd0714SAl Viro } 30596fbd0714SAl Viro if (d_in_lookup(dentry)) 30606fbd0714SAl Viro break; 3061d58ffd35SMiklos Szeredi 30626fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 30636fbd0714SAl Viro if (likely(error > 0)) 30646fbd0714SAl Viro break; 30656fbd0714SAl Viro if (error) 30666fbd0714SAl Viro goto out_dput; 30676fbd0714SAl Viro d_invalidate(dentry); 30686fbd0714SAl Viro dput(dentry); 30696fbd0714SAl Viro dentry = NULL; 30706fbd0714SAl Viro } 30716fbd0714SAl Viro if (dentry->d_inode) { 3072d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3073da5ebf5aSAl Viro return dentry; 30746c51e513SAl Viro } 3075d18e9008SMiklos Szeredi 30761643b43fSAl Viro /* 30771643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 30781643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 30791643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 30801643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 30811643b43fSAl Viro * 30821643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 30831643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 30841643b43fSAl Viro */ 30851643b43fSAl Viro if (open_flag & O_CREAT) { 30861643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 30871643b43fSAl Viro mode &= ~current_umask(); 30881643b43fSAl Viro if (unlikely(!got_write)) { 30891643b43fSAl Viro create_error = -EROFS; 30901643b43fSAl Viro open_flag &= ~O_CREAT; 30911643b43fSAl Viro if (open_flag & (O_EXCL | O_TRUNC)) 30921643b43fSAl Viro goto no_open; 30931643b43fSAl Viro /* No side effects, safe to clear O_CREAT */ 30941643b43fSAl Viro } else { 30951643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 30961643b43fSAl Viro if (create_error) { 30971643b43fSAl Viro open_flag &= ~O_CREAT; 30981643b43fSAl Viro if (open_flag & O_EXCL) 30991643b43fSAl Viro goto no_open; 31001643b43fSAl Viro } 31011643b43fSAl Viro } 31021643b43fSAl Viro } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && 31031643b43fSAl Viro unlikely(!got_write)) { 31041643b43fSAl Viro /* 31051643b43fSAl Viro * No O_CREATE -> atomicity not a requirement -> fall 31061643b43fSAl Viro * back to lookup + open 31071643b43fSAl Viro */ 31081643b43fSAl Viro goto no_open; 3109d18e9008SMiklos Szeredi } 3110d18e9008SMiklos Szeredi 31111643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 3112239eb983SAl Viro dentry = atomic_open(nd, dentry, file, op, open_flag, mode); 3113da5ebf5aSAl Viro if (unlikely(create_error) && dentry == ERR_PTR(-ENOENT)) 3114da5ebf5aSAl Viro dentry = ERR_PTR(create_error); 3115da5ebf5aSAl Viro return dentry; 3116239eb983SAl Viro } 311754ef4872SMiklos Szeredi 31181643b43fSAl Viro no_open: 31196fbd0714SAl Viro if (d_in_lookup(dentry)) { 312012fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 312112fa5e24SAl Viro nd->flags); 31226fbd0714SAl Viro d_lookup_done(dentry); 312312fa5e24SAl Viro if (unlikely(res)) { 312412fa5e24SAl Viro if (IS_ERR(res)) { 312512fa5e24SAl Viro error = PTR_ERR(res); 312612fa5e24SAl Viro goto out_dput; 312712fa5e24SAl Viro } 312812fa5e24SAl Viro dput(dentry); 312912fa5e24SAl Viro dentry = res; 313012fa5e24SAl Viro } 313154ef4872SMiklos Szeredi } 313254ef4872SMiklos Szeredi 3133d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 31341643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 313573a09dd9SAl Viro file->f_mode |= FMODE_CREATED; 3136ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3137ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3138ce8644fcSAl Viro error = -EACCES; 3139d58ffd35SMiklos Szeredi goto out_dput; 314064894cf8SAl Viro } 3141ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 31421643b43fSAl Viro open_flag & O_EXCL); 3143d58ffd35SMiklos Szeredi if (error) 3144d58ffd35SMiklos Szeredi goto out_dput; 3145ce8644fcSAl Viro fsnotify_create(dir_inode, dentry); 3146d58ffd35SMiklos Szeredi } 31471643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 31481643b43fSAl Viro error = create_error; 3149d58ffd35SMiklos Szeredi goto out_dput; 3150d58ffd35SMiklos Szeredi } 3151da5ebf5aSAl Viro return dentry; 3152d58ffd35SMiklos Szeredi 3153d58ffd35SMiklos Szeredi out_dput: 3154d58ffd35SMiklos Szeredi dput(dentry); 3155da5ebf5aSAl Viro return ERR_PTR(error); 3156d58ffd35SMiklos Szeredi } 3157d58ffd35SMiklos Szeredi 3158d58ffd35SMiklos Szeredi /* 3159fe2d35ffSAl Viro * Handle the last step of open() 316031e6b01fSNick Piggin */ 31611ccac622SAl Viro static const char *do_last(struct nameidata *nd, 31623ec2eef1SAl Viro struct file *file, const struct open_flags *op) 3163fb1cc555SAl Viro { 3164a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 31656404674aSAl Viro kuid_t dir_uid = nd->inode->i_uid; 31666404674aSAl Viro umode_t dir_mode = nd->inode->i_mode; 3167ca344a89SAl Viro int open_flag = op->open_flag; 316877d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 316964894cf8SAl Viro bool got_write = false; 3170bcda7652SAl Viro int acc_mode = op->acc_mode; 3171254cf582SAl Viro unsigned seq; 3172a1eb3315SMiklos Szeredi struct inode *inode; 3173da5ebf5aSAl Viro struct dentry *dentry; 3174b0417d2cSAl Viro const char *res; 317516c2cd71SAl Viro int error; 3176fb1cc555SAl Viro 3177c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3178c3e380b0SAl Viro nd->flags |= op->intent; 3179c3e380b0SAl Viro 3180bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 318156676ec3SAl Viro if (nd->depth) 318256676ec3SAl Viro put_link(nd); 3183fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3184deb106c6SAl Viro if (unlikely(error)) 31851ccac622SAl Viro return ERR_PTR(error); 3186e83db167SMiklos Szeredi goto finish_open; 31871f36f774SAl Viro } 3188a2c36b45SAl Viro 3189ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3190fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3191fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3192fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 319320e34357SAl Viro dentry = lookup_fast(nd, &inode, &seq); 319420e34357SAl Viro if (IS_ERR(dentry)) 31951ccac622SAl Viro return ERR_CAST(dentry); 319620e34357SAl Viro if (likely(dentry)) 319771574865SMiklos Szeredi goto finish_lookup; 319871574865SMiklos Szeredi 319937d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 32006583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3201b6183df7SMiklos Szeredi } else { 3202fe2d35ffSAl Viro /* create side of things */ 3203a3fbbde7SAl Viro /* 3204b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3205b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3206b6183df7SMiklos Szeredi * about to look up 3207a3fbbde7SAl Viro */ 32089f1fafeeSAl Viro error = complete_walk(nd); 3209e8bb73dfSAl Viro if (error) 32101ccac622SAl Viro return ERR_PTR(error); 3211fe2d35ffSAl Viro 3212c9b07eabSAl Viro audit_inode(nd->name, dir, AUDIT_INODE_PARENT); 32131f36f774SAl Viro /* trailing slashes? */ 3214deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 32151ccac622SAl Viro return ERR_PTR(-EISDIR); 3216b6183df7SMiklos Szeredi } 32171f36f774SAl Viro 32189cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 321964894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 322064894cf8SAl Viro if (!error) 322164894cf8SAl Viro got_write = true; 322264894cf8SAl Viro /* 322364894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 322464894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 322564894cf8SAl Viro * dropping this one anyway. 322664894cf8SAl Viro */ 322764894cf8SAl Viro } 32289cf843e3SAl Viro if (open_flag & O_CREAT) 32295955102cSAl Viro inode_lock(dir->d_inode); 32309cf843e3SAl Viro else 32319cf843e3SAl Viro inode_lock_shared(dir->d_inode); 3232da5ebf5aSAl Viro dentry = lookup_open(nd, file, op, got_write); 32339cf843e3SAl Viro if (open_flag & O_CREAT) 32345955102cSAl Viro inode_unlock(dir->d_inode); 32359cf843e3SAl Viro else 32369cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3237fb1cc555SAl Viro 3238da5ebf5aSAl Viro if (IS_ERR(dentry)) { 3239da5ebf5aSAl Viro error = PTR_ERR(dentry); 3240d58ffd35SMiklos Szeredi goto out; 3241da5ebf5aSAl Viro } 32426c0d46c4SAl Viro 324300a07c15SAl Viro if (file->f_mode & FMODE_OPENED) { 324473a09dd9SAl Viro if ((file->f_mode & FMODE_CREATED) || 3245496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 324677d660a8SMiklos Szeredi will_truncate = false; 3247d18e9008SMiklos Szeredi 324876ae2a5aSAl Viro audit_inode(nd->name, file->f_path.dentry, 0); 3249da5ebf5aSAl Viro dput(dentry); 3250d18e9008SMiklos Szeredi goto opened; 3251d18e9008SMiklos Szeredi } 3252d18e9008SMiklos Szeredi 325373a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) { 32549b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3255ca344a89SAl Viro open_flag &= ~O_TRUNC; 325677d660a8SMiklos Szeredi will_truncate = false; 325762fb4a15SAl Viro acc_mode = 0; 3258e73cabffSAl Viro dput(nd->path.dentry); 3259e73cabffSAl Viro nd->path.dentry = dentry; 3260e83db167SMiklos Szeredi goto finish_open_created; 3261fb1cc555SAl Viro } 3262fb1cc555SAl Viro 3263fb1cc555SAl Viro /* 3264d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3265d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3266d18e9008SMiklos Szeredi * necessary...) 3267d18e9008SMiklos Szeredi */ 326864894cf8SAl Viro if (got_write) { 3269d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 327064894cf8SAl Viro got_write = false; 3271d18e9008SMiklos Szeredi } 3272d18e9008SMiklos Szeredi 327320e34357SAl Viro finish_lookup: 327456676ec3SAl Viro if (nd->depth) 327556676ec3SAl Viro put_link(nd); 32768c4efe22SAl Viro res = step_into(nd, WALK_TRAILING, dentry, inode, seq); 3277b0417d2cSAl Viro if (unlikely(res)) { 32781ccac622SAl Viro nd->flags |= LOOKUP_PARENT; 32791ccac622SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 3280b0417d2cSAl Viro return res; 32811ccac622SAl Viro } 328231d1726dSAl Viro 328331d1726dSAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 328431d1726dSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 32851ccac622SAl Viro return ERR_PTR(-EEXIST); 328631d1726dSAl Viro } 3287bc77daa7SAl Viro finish_open: 32888f64fb1cSAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3289a3fbbde7SAl Viro error = complete_walk(nd); 3290fac7d191SAl Viro if (error) 32911ccac622SAl Viro return ERR_PTR(error); 329276ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 329330aba665SSalvatore Mesoraca if (open_flag & O_CREAT) { 3294fb1cc555SAl Viro error = -EISDIR; 329530aba665SSalvatore Mesoraca if (d_is_dir(nd->path.dentry)) 32962675a4ebSAl Viro goto out; 3297d0cb5018SAl Viro error = may_create_in_sticky(dir_mode, dir_uid, 329830aba665SSalvatore Mesoraca d_backing_inode(nd->path.dentry)); 329930aba665SSalvatore Mesoraca if (unlikely(error)) 330030aba665SSalvatore Mesoraca goto out; 330130aba665SSalvatore Mesoraca } 3302af2f5542SMiklos Szeredi error = -ENOTDIR; 330344b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 33042675a4ebSAl Viro goto out; 33054bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 330677d660a8SMiklos Szeredi will_truncate = false; 33076c0d46c4SAl Viro 33080f9d1a10SAl Viro if (will_truncate) { 33090f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 33100f9d1a10SAl Viro if (error) 33112675a4ebSAl Viro goto out; 331264894cf8SAl Viro got_write = true; 33130f9d1a10SAl Viro } 3314e83db167SMiklos Szeredi finish_open_created: 3315bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3316ca344a89SAl Viro if (error) 33172675a4ebSAl Viro goto out; 3318aad888f8SAl Viro BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */ 3319ae2bb293SAl Viro error = vfs_open(&nd->path, file); 3320fac7d191SAl Viro if (error) 3321015c3bbcSMiklos Szeredi goto out; 3322a8277b9bSMiklos Szeredi opened: 33236035a27bSAl Viro error = ima_file_check(file, op->acc_mode); 3324fe9ec829SAl Viro if (!error && will_truncate) 33252675a4ebSAl Viro error = handle_truncate(file); 3326ca344a89SAl Viro out: 3327c80567c8SAl Viro if (unlikely(error > 0)) { 3328c80567c8SAl Viro WARN_ON(1); 3329c80567c8SAl Viro error = -EINVAL; 3330c80567c8SAl Viro } 333164894cf8SAl Viro if (got_write) 33320f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 33331ccac622SAl Viro return ERR_PTR(error); 3334fb1cc555SAl Viro } 3335fb1cc555SAl Viro 3336af7bd4dcSAmir Goldstein struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode, int open_flag) 3337af7bd4dcSAmir Goldstein { 3338af7bd4dcSAmir Goldstein struct dentry *child = NULL; 3339af7bd4dcSAmir Goldstein struct inode *dir = dentry->d_inode; 3340af7bd4dcSAmir Goldstein struct inode *inode; 3341af7bd4dcSAmir Goldstein int error; 3342af7bd4dcSAmir Goldstein 3343af7bd4dcSAmir Goldstein /* we want directory to be writable */ 3344af7bd4dcSAmir Goldstein error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 3345af7bd4dcSAmir Goldstein if (error) 3346af7bd4dcSAmir Goldstein goto out_err; 3347af7bd4dcSAmir Goldstein error = -EOPNOTSUPP; 3348af7bd4dcSAmir Goldstein if (!dir->i_op->tmpfile) 3349af7bd4dcSAmir Goldstein goto out_err; 3350af7bd4dcSAmir Goldstein error = -ENOMEM; 3351cdf01226SDavid Howells child = d_alloc(dentry, &slash_name); 3352af7bd4dcSAmir Goldstein if (unlikely(!child)) 3353af7bd4dcSAmir Goldstein goto out_err; 3354af7bd4dcSAmir Goldstein error = dir->i_op->tmpfile(dir, child, mode); 3355af7bd4dcSAmir Goldstein if (error) 3356af7bd4dcSAmir Goldstein goto out_err; 3357af7bd4dcSAmir Goldstein error = -ENOENT; 3358af7bd4dcSAmir Goldstein inode = child->d_inode; 3359af7bd4dcSAmir Goldstein if (unlikely(!inode)) 3360af7bd4dcSAmir Goldstein goto out_err; 3361af7bd4dcSAmir Goldstein if (!(open_flag & O_EXCL)) { 3362af7bd4dcSAmir Goldstein spin_lock(&inode->i_lock); 3363af7bd4dcSAmir Goldstein inode->i_state |= I_LINKABLE; 3364af7bd4dcSAmir Goldstein spin_unlock(&inode->i_lock); 3365af7bd4dcSAmir Goldstein } 3366fdb2410fSMimi Zohar ima_post_create_tmpfile(inode); 3367af7bd4dcSAmir Goldstein return child; 3368af7bd4dcSAmir Goldstein 3369af7bd4dcSAmir Goldstein out_err: 3370af7bd4dcSAmir Goldstein dput(child); 3371af7bd4dcSAmir Goldstein return ERR_PTR(error); 3372af7bd4dcSAmir Goldstein } 3373af7bd4dcSAmir Goldstein EXPORT_SYMBOL(vfs_tmpfile); 3374af7bd4dcSAmir Goldstein 3375c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 337660545d0dSAl Viro const struct open_flags *op, 33773ec2eef1SAl Viro struct file *file) 337860545d0dSAl Viro { 3379625b6d10SAl Viro struct dentry *child; 3380625b6d10SAl Viro struct path path; 3381c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 338260545d0dSAl Viro if (unlikely(error)) 338360545d0dSAl Viro return error; 3384625b6d10SAl Viro error = mnt_want_write(path.mnt); 338560545d0dSAl Viro if (unlikely(error)) 338660545d0dSAl Viro goto out; 3387af7bd4dcSAmir Goldstein child = vfs_tmpfile(path.dentry, op->mode, op->open_flag); 3388af7bd4dcSAmir Goldstein error = PTR_ERR(child); 3389684e73beSHirofumi Nakagawa if (IS_ERR(child)) 339060545d0dSAl Viro goto out2; 3391625b6d10SAl Viro dput(path.dentry); 3392625b6d10SAl Viro path.dentry = child; 3393c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 339469a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 339562fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 339660545d0dSAl Viro if (error) 339760545d0dSAl Viro goto out2; 3398625b6d10SAl Viro file->f_path.mnt = path.mnt; 3399be12af3eSAl Viro error = finish_open(file, child, NULL); 340060545d0dSAl Viro out2: 3401625b6d10SAl Viro mnt_drop_write(path.mnt); 340260545d0dSAl Viro out: 3403625b6d10SAl Viro path_put(&path); 340460545d0dSAl Viro return error; 340560545d0dSAl Viro } 340660545d0dSAl Viro 34076ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 34086ac08709SAl Viro { 34096ac08709SAl Viro struct path path; 34106ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 34116ac08709SAl Viro if (!error) { 34126ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 3413ae2bb293SAl Viro error = vfs_open(&path, file); 34146ac08709SAl Viro path_put(&path); 34156ac08709SAl Viro } 34166ac08709SAl Viro return error; 34176ac08709SAl Viro } 34186ac08709SAl Viro 3419c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3420c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 34211da177e4SLinus Torvalds { 342230d90494SAl Viro struct file *file; 342313aab428SAl Viro int error; 342431e6b01fSNick Piggin 3425ea73ea72SAl Viro file = alloc_empty_file(op->open_flag, current_cred()); 34261afc99beSAl Viro if (IS_ERR(file)) 34271afc99beSAl Viro return file; 342831e6b01fSNick Piggin 3429bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 34303ec2eef1SAl Viro error = do_tmpfile(nd, flags, op, file); 34315f336e72SAl Viro } else if (unlikely(file->f_flags & O_PATH)) { 34326ac08709SAl Viro error = do_o_path(nd, flags, file); 34335f336e72SAl Viro } else { 34345f336e72SAl Viro const char *s = path_init(nd, flags); 34353bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 34361ccac622SAl Viro (s = do_last(nd, file, op)) != NULL) 34371ccac622SAl Viro ; 3438deb106c6SAl Viro terminate_walk(nd); 34395f336e72SAl Viro } 34407c1c01ecSAl Viro if (likely(!error)) { 3441aad888f8SAl Viro if (likely(file->f_mode & FMODE_OPENED)) 34427c1c01ecSAl Viro return file; 34437c1c01ecSAl Viro WARN_ON(1); 34447c1c01ecSAl Viro error = -EINVAL; 3445015c3bbcSMiklos Szeredi } 34467c1c01ecSAl Viro fput(file); 34472675a4ebSAl Viro if (error == -EOPENSTALE) { 34482675a4ebSAl Viro if (flags & LOOKUP_RCU) 34492675a4ebSAl Viro error = -ECHILD; 34502675a4ebSAl Viro else 34512675a4ebSAl Viro error = -ESTALE; 34522675a4ebSAl Viro } 34537c1c01ecSAl Viro return ERR_PTR(error); 3454de459215SKirill Korotaev } 34551da177e4SLinus Torvalds 3456669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3457f9652e10SAl Viro const struct open_flags *op) 345813aab428SAl Viro { 34599883d185SAl Viro struct nameidata nd; 3460f9652e10SAl Viro int flags = op->lookup_flags; 346113aab428SAl Viro struct file *filp; 346213aab428SAl Viro 34639883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3464c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 346513aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3466c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 346713aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3468c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 34699883d185SAl Viro restore_nameidata(); 347013aab428SAl Viro return filp; 347113aab428SAl Viro } 347213aab428SAl Viro 347373d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3474f9652e10SAl Viro const char *name, const struct open_flags *op) 347573d049a4SAl Viro { 34769883d185SAl Viro struct nameidata nd; 347773d049a4SAl Viro struct file *file; 347851689104SPaul Moore struct filename *filename; 3479f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 348073d049a4SAl Viro 348173d049a4SAl Viro nd.root.mnt = mnt; 348273d049a4SAl Viro nd.root.dentry = dentry; 348373d049a4SAl Viro 3484b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 348573d049a4SAl Viro return ERR_PTR(-ELOOP); 348673d049a4SAl Viro 348751689104SPaul Moore filename = getname_kernel(name); 3488a1c83681SViresh Kumar if (IS_ERR(filename)) 348951689104SPaul Moore return ERR_CAST(filename); 349051689104SPaul Moore 34919883d185SAl Viro set_nameidata(&nd, -1, filename); 3492c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 349373d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3494c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 349573d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3496c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 34979883d185SAl Viro restore_nameidata(); 349851689104SPaul Moore putname(filename); 349973d049a4SAl Viro return file; 350073d049a4SAl Viro } 350173d049a4SAl Viro 3502fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 35031ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 35041da177e4SLinus Torvalds { 3505c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3506391172c4SAl Viro struct qstr last; 3507391172c4SAl Viro int type; 3508c30dabfeSJan Kara int err2; 35091ac12b4bSJeff Layton int error; 35101ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 35111ac12b4bSJeff Layton 35121ac12b4bSJeff Layton /* 35131ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 35141ac12b4bSJeff Layton * other flags passed in are ignored! 35151ac12b4bSJeff Layton */ 35161ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 35171ac12b4bSJeff Layton 35185c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 35195c31b6ceSAl Viro if (IS_ERR(name)) 35205c31b6ceSAl Viro return ERR_CAST(name); 35211da177e4SLinus Torvalds 3522c663e5d8SChristoph Hellwig /* 3523c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3524c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3525c663e5d8SChristoph Hellwig */ 35265c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3527ed75e95dSAl Viro goto out; 3528c663e5d8SChristoph Hellwig 3529c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3530391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3531c663e5d8SChristoph Hellwig /* 3532c663e5d8SChristoph Hellwig * Do the final lookup. 3533c663e5d8SChristoph Hellwig */ 3534391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 35355955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3536391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 35371da177e4SLinus Torvalds if (IS_ERR(dentry)) 3538a8104a9fSAl Viro goto unlock; 3539c663e5d8SChristoph Hellwig 3540a8104a9fSAl Viro error = -EEXIST; 3541b18825a7SDavid Howells if (d_is_positive(dentry)) 3542a8104a9fSAl Viro goto fail; 3543b18825a7SDavid Howells 3544c663e5d8SChristoph Hellwig /* 3545c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3546c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3547c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3548c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3549c663e5d8SChristoph Hellwig */ 3550391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3551a8104a9fSAl Viro error = -ENOENT; 3552ed75e95dSAl Viro goto fail; 3553e9baf6e5SAl Viro } 3554c30dabfeSJan Kara if (unlikely(err2)) { 3555c30dabfeSJan Kara error = err2; 3556a8104a9fSAl Viro goto fail; 3557c30dabfeSJan Kara } 3558181c37b6SAl Viro putname(name); 3559e9baf6e5SAl Viro return dentry; 35601da177e4SLinus Torvalds fail: 3561a8104a9fSAl Viro dput(dentry); 3562a8104a9fSAl Viro dentry = ERR_PTR(error); 3563a8104a9fSAl Viro unlock: 35645955102cSAl Viro inode_unlock(path->dentry->d_inode); 3565c30dabfeSJan Kara if (!err2) 3566391172c4SAl Viro mnt_drop_write(path->mnt); 3567ed75e95dSAl Viro out: 3568391172c4SAl Viro path_put(path); 3569181c37b6SAl Viro putname(name); 3570ed75e95dSAl Viro return dentry; 3571dae6ad8fSAl Viro } 3572fa14a0b8SAl Viro 3573fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3574fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3575fa14a0b8SAl Viro { 3576181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3577181c37b6SAl Viro path, lookup_flags); 3578fa14a0b8SAl Viro } 3579dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3580dae6ad8fSAl Viro 3581921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3582921a1650SAl Viro { 3583921a1650SAl Viro dput(dentry); 35845955102cSAl Viro inode_unlock(path->dentry->d_inode); 3585a8104a9fSAl Viro mnt_drop_write(path->mnt); 3586921a1650SAl Viro path_put(path); 3587921a1650SAl Viro } 3588921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3589921a1650SAl Viro 3590520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 35911ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3592dae6ad8fSAl Viro { 3593181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3594dae6ad8fSAl Viro } 3595dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3596dae6ad8fSAl Viro 35971a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 35981da177e4SLinus Torvalds { 3599a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36001da177e4SLinus Torvalds 36011da177e4SLinus Torvalds if (error) 36021da177e4SLinus Torvalds return error; 36031da177e4SLinus Torvalds 360494f82008SChristian Brauner if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 36051da177e4SLinus Torvalds return -EPERM; 36061da177e4SLinus Torvalds 3607acfa4380SAl Viro if (!dir->i_op->mknod) 36081da177e4SLinus Torvalds return -EPERM; 36091da177e4SLinus Torvalds 361008ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 361108ce5f16SSerge E. Hallyn if (error) 361208ce5f16SSerge E. Hallyn return error; 361308ce5f16SSerge E. Hallyn 36141da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 36151da177e4SLinus Torvalds if (error) 36161da177e4SLinus Torvalds return error; 36171da177e4SLinus Torvalds 36181da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3619a74574aaSStephen Smalley if (!error) 3620f38aa942SAmy Griffis fsnotify_create(dir, dentry); 36211da177e4SLinus Torvalds return error; 36221da177e4SLinus Torvalds } 36234d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 36241da177e4SLinus Torvalds 3625f69aac00SAl Viro static int may_mknod(umode_t mode) 3626463c3197SDave Hansen { 3627463c3197SDave Hansen switch (mode & S_IFMT) { 3628463c3197SDave Hansen case S_IFREG: 3629463c3197SDave Hansen case S_IFCHR: 3630463c3197SDave Hansen case S_IFBLK: 3631463c3197SDave Hansen case S_IFIFO: 3632463c3197SDave Hansen case S_IFSOCK: 3633463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3634463c3197SDave Hansen return 0; 3635463c3197SDave Hansen case S_IFDIR: 3636463c3197SDave Hansen return -EPERM; 3637463c3197SDave Hansen default: 3638463c3197SDave Hansen return -EINVAL; 3639463c3197SDave Hansen } 3640463c3197SDave Hansen } 3641463c3197SDave Hansen 364287c4e192SDominik Brodowski long do_mknodat(int dfd, const char __user *filename, umode_t mode, 364387c4e192SDominik Brodowski unsigned int dev) 36441da177e4SLinus Torvalds { 36451da177e4SLinus Torvalds struct dentry *dentry; 3646dae6ad8fSAl Viro struct path path; 3647dae6ad8fSAl Viro int error; 3648972567f1SJeff Layton unsigned int lookup_flags = 0; 36491da177e4SLinus Torvalds 36508e4bfca1SAl Viro error = may_mknod(mode); 36518e4bfca1SAl Viro if (error) 36528e4bfca1SAl Viro return error; 3653972567f1SJeff Layton retry: 3654972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3655dae6ad8fSAl Viro if (IS_ERR(dentry)) 3656dae6ad8fSAl Viro return PTR_ERR(dentry); 36572ad94ae6SAl Viro 3658dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3659ce3b0f8dSAl Viro mode &= ~current_umask(); 3660dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3661be6d3e56SKentaro Takeda if (error) 3662a8104a9fSAl Viro goto out; 36631da177e4SLinus Torvalds switch (mode & S_IFMT) { 36641da177e4SLinus Torvalds case 0: case S_IFREG: 3665312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 366605d1a717SMimi Zohar if (!error) 366705d1a717SMimi Zohar ima_post_path_mknod(dentry); 36681da177e4SLinus Torvalds break; 36691da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3670dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 36711da177e4SLinus Torvalds new_decode_dev(dev)); 36721da177e4SLinus Torvalds break; 36731da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3674dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 36751da177e4SLinus Torvalds break; 36761da177e4SLinus Torvalds } 3677a8104a9fSAl Viro out: 3678921a1650SAl Viro done_path_create(&path, dentry); 3679972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3680972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3681972567f1SJeff Layton goto retry; 3682972567f1SJeff Layton } 36831da177e4SLinus Torvalds return error; 36841da177e4SLinus Torvalds } 36851da177e4SLinus Torvalds 368687c4e192SDominik Brodowski SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 368787c4e192SDominik Brodowski unsigned int, dev) 368887c4e192SDominik Brodowski { 368987c4e192SDominik Brodowski return do_mknodat(dfd, filename, mode, dev); 369087c4e192SDominik Brodowski } 369187c4e192SDominik Brodowski 36928208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 36935590ff0dSUlrich Drepper { 369487c4e192SDominik Brodowski return do_mknodat(AT_FDCWD, filename, mode, dev); 36955590ff0dSUlrich Drepper } 36965590ff0dSUlrich Drepper 369718bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 36981da177e4SLinus Torvalds { 3699a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 37008de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 37011da177e4SLinus Torvalds 37021da177e4SLinus Torvalds if (error) 37031da177e4SLinus Torvalds return error; 37041da177e4SLinus Torvalds 3705acfa4380SAl Viro if (!dir->i_op->mkdir) 37061da177e4SLinus Torvalds return -EPERM; 37071da177e4SLinus Torvalds 37081da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 37091da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 37101da177e4SLinus Torvalds if (error) 37111da177e4SLinus Torvalds return error; 37121da177e4SLinus Torvalds 37138de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 37148de52778SAl Viro return -EMLINK; 37158de52778SAl Viro 37161da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3717a74574aaSStephen Smalley if (!error) 3718f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 37191da177e4SLinus Torvalds return error; 37201da177e4SLinus Torvalds } 37214d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 37221da177e4SLinus Torvalds 37230101db7aSDominik Brodowski long do_mkdirat(int dfd, const char __user *pathname, umode_t mode) 37241da177e4SLinus Torvalds { 37256902d925SDave Hansen struct dentry *dentry; 3726dae6ad8fSAl Viro struct path path; 3727dae6ad8fSAl Viro int error; 3728b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 37291da177e4SLinus Torvalds 3730b76d8b82SJeff Layton retry: 3731b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 37326902d925SDave Hansen if (IS_ERR(dentry)) 3733dae6ad8fSAl Viro return PTR_ERR(dentry); 37346902d925SDave Hansen 3735dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3736ce3b0f8dSAl Viro mode &= ~current_umask(); 3737dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3738a8104a9fSAl Viro if (!error) 3739dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3740921a1650SAl Viro done_path_create(&path, dentry); 3741b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3742b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3743b76d8b82SJeff Layton goto retry; 3744b76d8b82SJeff Layton } 37451da177e4SLinus Torvalds return error; 37461da177e4SLinus Torvalds } 37471da177e4SLinus Torvalds 37480101db7aSDominik Brodowski SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 37490101db7aSDominik Brodowski { 37500101db7aSDominik Brodowski return do_mkdirat(dfd, pathname, mode); 37510101db7aSDominik Brodowski } 37520101db7aSDominik Brodowski 3753a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 37545590ff0dSUlrich Drepper { 37550101db7aSDominik Brodowski return do_mkdirat(AT_FDCWD, pathname, mode); 37565590ff0dSUlrich Drepper } 37575590ff0dSUlrich Drepper 37581da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 37591da177e4SLinus Torvalds { 37601da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 37611da177e4SLinus Torvalds 37621da177e4SLinus Torvalds if (error) 37631da177e4SLinus Torvalds return error; 37641da177e4SLinus Torvalds 3765acfa4380SAl Viro if (!dir->i_op->rmdir) 37661da177e4SLinus Torvalds return -EPERM; 37671da177e4SLinus Torvalds 37681d2ef590SAl Viro dget(dentry); 37695955102cSAl Viro inode_lock(dentry->d_inode); 3770912dbc15SSage Weil 37711da177e4SLinus Torvalds error = -EBUSY; 37727af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3773912dbc15SSage Weil goto out; 3774912dbc15SSage Weil 37751da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3776912dbc15SSage Weil if (error) 3777912dbc15SSage Weil goto out; 3778912dbc15SSage Weil 37791da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3780912dbc15SSage Weil if (error) 3781912dbc15SSage Weil goto out; 3782912dbc15SSage Weil 37838767712fSAl Viro shrink_dcache_parent(dentry); 37841da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3785d83c49f3SAl Viro dont_mount(dentry); 37868ed936b5SEric W. Biederman detach_mounts(dentry); 3787116b9731SAmir Goldstein fsnotify_rmdir(dir, dentry); 37881da177e4SLinus Torvalds 3789912dbc15SSage Weil out: 37905955102cSAl Viro inode_unlock(dentry->d_inode); 37911d2ef590SAl Viro dput(dentry); 3792912dbc15SSage Weil if (!error) 3793912dbc15SSage Weil d_delete(dentry); 37941da177e4SLinus Torvalds return error; 37951da177e4SLinus Torvalds } 37964d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 37971da177e4SLinus Torvalds 3798f459dffaSDominik Brodowski long do_rmdir(int dfd, const char __user *pathname) 37991da177e4SLinus Torvalds { 38001da177e4SLinus Torvalds int error = 0; 380191a27b2aSJeff Layton struct filename *name; 38021da177e4SLinus Torvalds struct dentry *dentry; 3803f5beed75SAl Viro struct path path; 3804f5beed75SAl Viro struct qstr last; 3805f5beed75SAl Viro int type; 3806c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3807c6ee9206SJeff Layton retry: 3808c1d4dd27SAl Viro name = filename_parentat(dfd, getname(pathname), lookup_flags, 3809c1d4dd27SAl Viro &path, &last, &type); 381091a27b2aSJeff Layton if (IS_ERR(name)) 381191a27b2aSJeff Layton return PTR_ERR(name); 38121da177e4SLinus Torvalds 3813f5beed75SAl Viro switch (type) { 38141da177e4SLinus Torvalds case LAST_DOTDOT: 38151da177e4SLinus Torvalds error = -ENOTEMPTY; 38161da177e4SLinus Torvalds goto exit1; 38171da177e4SLinus Torvalds case LAST_DOT: 38181da177e4SLinus Torvalds error = -EINVAL; 38191da177e4SLinus Torvalds goto exit1; 38201da177e4SLinus Torvalds case LAST_ROOT: 38211da177e4SLinus Torvalds error = -EBUSY; 38221da177e4SLinus Torvalds goto exit1; 38231da177e4SLinus Torvalds } 38240612d9fbSOGAWA Hirofumi 3825f5beed75SAl Viro error = mnt_want_write(path.mnt); 3826c30dabfeSJan Kara if (error) 3827c30dabfeSJan Kara goto exit1; 38280612d9fbSOGAWA Hirofumi 38295955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3830f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38311da177e4SLinus Torvalds error = PTR_ERR(dentry); 38326902d925SDave Hansen if (IS_ERR(dentry)) 38336902d925SDave Hansen goto exit2; 3834e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3835e6bc45d6STheodore Ts'o error = -ENOENT; 3836e6bc45d6STheodore Ts'o goto exit3; 3837e6bc45d6STheodore Ts'o } 3838f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3839be6d3e56SKentaro Takeda if (error) 3840c30dabfeSJan Kara goto exit3; 3841f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 38420622753bSDave Hansen exit3: 38431da177e4SLinus Torvalds dput(dentry); 38446902d925SDave Hansen exit2: 38455955102cSAl Viro inode_unlock(path.dentry->d_inode); 3846f5beed75SAl Viro mnt_drop_write(path.mnt); 38471da177e4SLinus Torvalds exit1: 3848f5beed75SAl Viro path_put(&path); 38491da177e4SLinus Torvalds putname(name); 3850c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3851c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3852c6ee9206SJeff Layton goto retry; 3853c6ee9206SJeff Layton } 38541da177e4SLinus Torvalds return error; 38551da177e4SLinus Torvalds } 38561da177e4SLinus Torvalds 38573cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 38585590ff0dSUlrich Drepper { 38595590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 38605590ff0dSUlrich Drepper } 38615590ff0dSUlrich Drepper 3862b21996e3SJ. Bruce Fields /** 3863b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3864b21996e3SJ. Bruce Fields * @dir: parent directory 3865b21996e3SJ. Bruce Fields * @dentry: victim 3866b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3867b21996e3SJ. Bruce Fields * 3868b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3869b21996e3SJ. Bruce Fields * 3870b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3871b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3872b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3873b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3874b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3875b21996e3SJ. Bruce Fields * 3876b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3877b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3878b21996e3SJ. Bruce Fields * to be NFS exported. 3879b21996e3SJ. Bruce Fields */ 3880b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 38811da177e4SLinus Torvalds { 38829accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 38831da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 38841da177e4SLinus Torvalds 38851da177e4SLinus Torvalds if (error) 38861da177e4SLinus Torvalds return error; 38871da177e4SLinus Torvalds 3888acfa4380SAl Viro if (!dir->i_op->unlink) 38891da177e4SLinus Torvalds return -EPERM; 38901da177e4SLinus Torvalds 38915955102cSAl Viro inode_lock(target); 38928ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 38931da177e4SLinus Torvalds error = -EBUSY; 38941da177e4SLinus Torvalds else { 38951da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3896bec1052eSAl Viro if (!error) { 38975a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 38985a14696cSJ. Bruce Fields if (error) 3899b21996e3SJ. Bruce Fields goto out; 39001da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 39018ed936b5SEric W. Biederman if (!error) { 3902d83c49f3SAl Viro dont_mount(dentry); 39038ed936b5SEric W. Biederman detach_mounts(dentry); 3904116b9731SAmir Goldstein fsnotify_unlink(dir, dentry); 39058ed936b5SEric W. Biederman } 3906bec1052eSAl Viro } 39071da177e4SLinus Torvalds } 3908b21996e3SJ. Bruce Fields out: 39095955102cSAl Viro inode_unlock(target); 39101da177e4SLinus Torvalds 39111da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 39121da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 39139accbb97SJ. Bruce Fields fsnotify_link_count(target); 39141da177e4SLinus Torvalds d_delete(dentry); 39151da177e4SLinus Torvalds } 39160eeca283SRobert Love 39171da177e4SLinus Torvalds return error; 39181da177e4SLinus Torvalds } 39194d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 39201da177e4SLinus Torvalds 39211da177e4SLinus Torvalds /* 39221da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 39231b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 39241da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 39251da177e4SLinus Torvalds * while waiting on the I/O. 39261da177e4SLinus Torvalds */ 3927da2f1362SChristoph Hellwig long do_unlinkat(int dfd, struct filename *name) 39281da177e4SLinus Torvalds { 39292ad94ae6SAl Viro int error; 39301da177e4SLinus Torvalds struct dentry *dentry; 3931f5beed75SAl Viro struct path path; 3932f5beed75SAl Viro struct qstr last; 3933f5beed75SAl Viro int type; 39341da177e4SLinus Torvalds struct inode *inode = NULL; 3935b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 39365d18f813SJeff Layton unsigned int lookup_flags = 0; 39375d18f813SJeff Layton retry: 3938da2f1362SChristoph Hellwig name = filename_parentat(dfd, name, lookup_flags, &path, &last, &type); 393991a27b2aSJeff Layton if (IS_ERR(name)) 394091a27b2aSJeff Layton return PTR_ERR(name); 39412ad94ae6SAl Viro 39421da177e4SLinus Torvalds error = -EISDIR; 3943f5beed75SAl Viro if (type != LAST_NORM) 39441da177e4SLinus Torvalds goto exit1; 39450612d9fbSOGAWA Hirofumi 3946f5beed75SAl Viro error = mnt_want_write(path.mnt); 3947c30dabfeSJan Kara if (error) 3948c30dabfeSJan Kara goto exit1; 3949b21996e3SJ. Bruce Fields retry_deleg: 39505955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3951f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 39521da177e4SLinus Torvalds error = PTR_ERR(dentry); 39531da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 39541da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3955f5beed75SAl Viro if (last.name[last.len]) 395650338b88STörök Edwin goto slashes; 39571da177e4SLinus Torvalds inode = dentry->d_inode; 3958b18825a7SDavid Howells if (d_is_negative(dentry)) 3959e6bc45d6STheodore Ts'o goto slashes; 39607de9c6eeSAl Viro ihold(inode); 3961f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3962be6d3e56SKentaro Takeda if (error) 3963c30dabfeSJan Kara goto exit2; 3964f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 39651da177e4SLinus Torvalds exit2: 39661da177e4SLinus Torvalds dput(dentry); 39671da177e4SLinus Torvalds } 39685955102cSAl Viro inode_unlock(path.dentry->d_inode); 39691da177e4SLinus Torvalds if (inode) 39701da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3971b21996e3SJ. Bruce Fields inode = NULL; 3972b21996e3SJ. Bruce Fields if (delegated_inode) { 39735a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3974b21996e3SJ. Bruce Fields if (!error) 3975b21996e3SJ. Bruce Fields goto retry_deleg; 3976b21996e3SJ. Bruce Fields } 3977f5beed75SAl Viro mnt_drop_write(path.mnt); 39781da177e4SLinus Torvalds exit1: 3979f5beed75SAl Viro path_put(&path); 39805d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 39815d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 39825d18f813SJeff Layton inode = NULL; 39835d18f813SJeff Layton goto retry; 39845d18f813SJeff Layton } 3985da2f1362SChristoph Hellwig putname(name); 39861da177e4SLinus Torvalds return error; 39871da177e4SLinus Torvalds 39881da177e4SLinus Torvalds slashes: 3989b18825a7SDavid Howells if (d_is_negative(dentry)) 3990b18825a7SDavid Howells error = -ENOENT; 399144b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3992b18825a7SDavid Howells error = -EISDIR; 3993b18825a7SDavid Howells else 3994b18825a7SDavid Howells error = -ENOTDIR; 39951da177e4SLinus Torvalds goto exit2; 39961da177e4SLinus Torvalds } 39971da177e4SLinus Torvalds 39982e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 39995590ff0dSUlrich Drepper { 40005590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 40015590ff0dSUlrich Drepper return -EINVAL; 40025590ff0dSUlrich Drepper 40035590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 40045590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 40055590ff0dSUlrich Drepper 4006da2f1362SChristoph Hellwig return do_unlinkat(dfd, getname(pathname)); 40075590ff0dSUlrich Drepper } 40085590ff0dSUlrich Drepper 40093480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 40105590ff0dSUlrich Drepper { 4011da2f1362SChristoph Hellwig return do_unlinkat(AT_FDCWD, getname(pathname)); 40125590ff0dSUlrich Drepper } 40135590ff0dSUlrich Drepper 4014db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 40151da177e4SLinus Torvalds { 4016a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 40171da177e4SLinus Torvalds 40181da177e4SLinus Torvalds if (error) 40191da177e4SLinus Torvalds return error; 40201da177e4SLinus Torvalds 4021acfa4380SAl Viro if (!dir->i_op->symlink) 40221da177e4SLinus Torvalds return -EPERM; 40231da177e4SLinus Torvalds 40241da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 40251da177e4SLinus Torvalds if (error) 40261da177e4SLinus Torvalds return error; 40271da177e4SLinus Torvalds 40281da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 4029a74574aaSStephen Smalley if (!error) 4030f38aa942SAmy Griffis fsnotify_create(dir, dentry); 40311da177e4SLinus Torvalds return error; 40321da177e4SLinus Torvalds } 40334d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 40341da177e4SLinus Torvalds 4035b724e846SDominik Brodowski long do_symlinkat(const char __user *oldname, int newdfd, 4036b724e846SDominik Brodowski const char __user *newname) 40371da177e4SLinus Torvalds { 40382ad94ae6SAl Viro int error; 403991a27b2aSJeff Layton struct filename *from; 40406902d925SDave Hansen struct dentry *dentry; 4041dae6ad8fSAl Viro struct path path; 4042f46d3567SJeff Layton unsigned int lookup_flags = 0; 40431da177e4SLinus Torvalds 40441da177e4SLinus Torvalds from = getname(oldname); 40451da177e4SLinus Torvalds if (IS_ERR(from)) 40461da177e4SLinus Torvalds return PTR_ERR(from); 4047f46d3567SJeff Layton retry: 4048f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 40491da177e4SLinus Torvalds error = PTR_ERR(dentry); 40506902d925SDave Hansen if (IS_ERR(dentry)) 4051dae6ad8fSAl Viro goto out_putname; 40526902d925SDave Hansen 405391a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4054a8104a9fSAl Viro if (!error) 405591a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4056921a1650SAl Viro done_path_create(&path, dentry); 4057f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4058f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4059f46d3567SJeff Layton goto retry; 4060f46d3567SJeff Layton } 40616902d925SDave Hansen out_putname: 40621da177e4SLinus Torvalds putname(from); 40631da177e4SLinus Torvalds return error; 40641da177e4SLinus Torvalds } 40651da177e4SLinus Torvalds 4066b724e846SDominik Brodowski SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 4067b724e846SDominik Brodowski int, newdfd, const char __user *, newname) 4068b724e846SDominik Brodowski { 4069b724e846SDominik Brodowski return do_symlinkat(oldname, newdfd, newname); 4070b724e846SDominik Brodowski } 4071b724e846SDominik Brodowski 40723480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 40735590ff0dSUlrich Drepper { 4074b724e846SDominik Brodowski return do_symlinkat(oldname, AT_FDCWD, newname); 40755590ff0dSUlrich Drepper } 40765590ff0dSUlrich Drepper 4077146a8595SJ. Bruce Fields /** 4078146a8595SJ. Bruce Fields * vfs_link - create a new link 4079146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4080146a8595SJ. Bruce Fields * @dir: new parent 4081146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4082146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4083146a8595SJ. Bruce Fields * 4084146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4085146a8595SJ. Bruce Fields * 4086146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4087146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4088146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4089146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4090146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4091146a8595SJ. Bruce Fields * 4092146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4093146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4094146a8595SJ. Bruce Fields * to be NFS exported. 4095146a8595SJ. Bruce Fields */ 4096146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 40971da177e4SLinus Torvalds { 40981da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 40998de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 41001da177e4SLinus Torvalds int error; 41011da177e4SLinus Torvalds 41021da177e4SLinus Torvalds if (!inode) 41031da177e4SLinus Torvalds return -ENOENT; 41041da177e4SLinus Torvalds 4105a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 41061da177e4SLinus Torvalds if (error) 41071da177e4SLinus Torvalds return error; 41081da177e4SLinus Torvalds 41091da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 41101da177e4SLinus Torvalds return -EXDEV; 41111da177e4SLinus Torvalds 41121da177e4SLinus Torvalds /* 41131da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 41141da177e4SLinus Torvalds */ 41151da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 41161da177e4SLinus Torvalds return -EPERM; 41170bd23d09SEric W. Biederman /* 41180bd23d09SEric W. Biederman * Updating the link count will likely cause i_uid and i_gid to 41190bd23d09SEric W. Biederman * be writen back improperly if their true value is unknown to 41200bd23d09SEric W. Biederman * the vfs. 41210bd23d09SEric W. Biederman */ 41220bd23d09SEric W. Biederman if (HAS_UNMAPPED_ID(inode)) 41230bd23d09SEric W. Biederman return -EPERM; 4124acfa4380SAl Viro if (!dir->i_op->link) 41251da177e4SLinus Torvalds return -EPERM; 41267e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 41271da177e4SLinus Torvalds return -EPERM; 41281da177e4SLinus Torvalds 41291da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 41301da177e4SLinus Torvalds if (error) 41311da177e4SLinus Torvalds return error; 41321da177e4SLinus Torvalds 41335955102cSAl Viro inode_lock(inode); 4134aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4135f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4136aae8a97dSAneesh Kumar K.V error = -ENOENT; 41378de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 41388de52778SAl Viro error = -EMLINK; 4139146a8595SJ. Bruce Fields else { 4140146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4141146a8595SJ. Bruce Fields if (!error) 41421da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4143146a8595SJ. Bruce Fields } 4144f4e0c30cSAl Viro 4145f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4146f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4147f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4148f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4149f4e0c30cSAl Viro } 41505955102cSAl Viro inode_unlock(inode); 4151e31e14ecSStephen Smalley if (!error) 41527e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 41531da177e4SLinus Torvalds return error; 41541da177e4SLinus Torvalds } 41554d359507SAl Viro EXPORT_SYMBOL(vfs_link); 41561da177e4SLinus Torvalds 41571da177e4SLinus Torvalds /* 41581da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 41591da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 41601da177e4SLinus Torvalds * newname. --KAB 41611da177e4SLinus Torvalds * 41621da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 41631da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 41641da177e4SLinus Torvalds * and other special files. --ADM 41651da177e4SLinus Torvalds */ 416646ea89ebSDominik Brodowski int do_linkat(int olddfd, const char __user *oldname, int newdfd, 416746ea89ebSDominik Brodowski const char __user *newname, int flags) 41681da177e4SLinus Torvalds { 41691da177e4SLinus Torvalds struct dentry *new_dentry; 4170dae6ad8fSAl Viro struct path old_path, new_path; 4171146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 417211a7b371SAneesh Kumar K.V int how = 0; 41731da177e4SLinus Torvalds int error; 41741da177e4SLinus Torvalds 417511a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4176c04030e1SUlrich Drepper return -EINVAL; 417711a7b371SAneesh Kumar K.V /* 4178f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4179f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4180f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 418111a7b371SAneesh Kumar K.V */ 4182f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4183f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4184f0cc6ffbSLinus Torvalds return -ENOENT; 418511a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4186f0cc6ffbSLinus Torvalds } 4187c04030e1SUlrich Drepper 418811a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 418911a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4190442e31caSJeff Layton retry: 419111a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 41921da177e4SLinus Torvalds if (error) 41932ad94ae6SAl Viro return error; 41942ad94ae6SAl Viro 4195442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4196442e31caSJeff Layton (how & LOOKUP_REVAL)); 41971da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 41986902d925SDave Hansen if (IS_ERR(new_dentry)) 4199dae6ad8fSAl Viro goto out; 4200dae6ad8fSAl Viro 4201dae6ad8fSAl Viro error = -EXDEV; 4202dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4203dae6ad8fSAl Viro goto out_dput; 4204800179c9SKees Cook error = may_linkat(&old_path); 4205800179c9SKees Cook if (unlikely(error)) 4206800179c9SKees Cook goto out_dput; 4207dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4208be6d3e56SKentaro Takeda if (error) 4209a8104a9fSAl Viro goto out_dput; 4210146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 421175c3f29dSDave Hansen out_dput: 4212921a1650SAl Viro done_path_create(&new_path, new_dentry); 4213146a8595SJ. Bruce Fields if (delegated_inode) { 4214146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4215d22e6338SOleg Drokin if (!error) { 4216d22e6338SOleg Drokin path_put(&old_path); 4217146a8595SJ. Bruce Fields goto retry; 4218146a8595SJ. Bruce Fields } 4219d22e6338SOleg Drokin } 4220442e31caSJeff Layton if (retry_estale(error, how)) { 4221d22e6338SOleg Drokin path_put(&old_path); 4222442e31caSJeff Layton how |= LOOKUP_REVAL; 4223442e31caSJeff Layton goto retry; 4224442e31caSJeff Layton } 42251da177e4SLinus Torvalds out: 42262d8f3038SAl Viro path_put(&old_path); 42271da177e4SLinus Torvalds 42281da177e4SLinus Torvalds return error; 42291da177e4SLinus Torvalds } 42301da177e4SLinus Torvalds 423146ea89ebSDominik Brodowski SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 423246ea89ebSDominik Brodowski int, newdfd, const char __user *, newname, int, flags) 423346ea89ebSDominik Brodowski { 423446ea89ebSDominik Brodowski return do_linkat(olddfd, oldname, newdfd, newname, flags); 423546ea89ebSDominik Brodowski } 423646ea89ebSDominik Brodowski 42373480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 42385590ff0dSUlrich Drepper { 423946ea89ebSDominik Brodowski return do_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 42405590ff0dSUlrich Drepper } 42415590ff0dSUlrich Drepper 4242bc27027aSMiklos Szeredi /** 4243bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4244bc27027aSMiklos Szeredi * @old_dir: parent of source 4245bc27027aSMiklos Szeredi * @old_dentry: source 4246bc27027aSMiklos Szeredi * @new_dir: parent of destination 4247bc27027aSMiklos Szeredi * @new_dentry: destination 4248bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4249520c8b16SMiklos Szeredi * @flags: rename flags 4250bc27027aSMiklos Szeredi * 4251bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4252bc27027aSMiklos Szeredi * 4253bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4254bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4255bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4256bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4257bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4258bc27027aSMiklos Szeredi * so. 4259bc27027aSMiklos Szeredi * 4260bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4261bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4262bc27027aSMiklos Szeredi * to be NFS exported. 4263bc27027aSMiklos Szeredi * 42641da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 42651da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 42661da177e4SLinus Torvalds * Problems: 42670117d427SMauro Carvalho Chehab * 4268d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 42691da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 42701da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4271a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 42721da177e4SLinus Torvalds * story. 42736cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 42746cedba89SJ. Bruce Fields * and source (if it is not a directory). 42751b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 42761da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 42771da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4278a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 42791da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 42801da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 42811da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4282a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 42831da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 42841da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 42851da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4286e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 42871b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 42881da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4289c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 42901da177e4SLinus Torvalds * locking]. 42911da177e4SLinus Torvalds */ 42921da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 42938e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4294520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 42951da177e4SLinus Torvalds { 42961da177e4SLinus Torvalds int error; 4297bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 4298bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4299bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4300da1ce067SMiklos Szeredi bool new_is_dir = false; 4301da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 430249d31c2fSAl Viro struct name_snapshot old_name; 43031da177e4SLinus Torvalds 43048d3e2936SMiklos Szeredi if (source == target) 43051da177e4SLinus Torvalds return 0; 43061da177e4SLinus Torvalds 43071da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 43081da177e4SLinus Torvalds if (error) 43091da177e4SLinus Torvalds return error; 43101da177e4SLinus Torvalds 4311da1ce067SMiklos Szeredi if (!target) { 4312a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4313da1ce067SMiklos Szeredi } else { 4314da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4315da1ce067SMiklos Szeredi 4316da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43171da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4318da1ce067SMiklos Szeredi else 4319da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4320da1ce067SMiklos Szeredi } 43211da177e4SLinus Torvalds if (error) 43221da177e4SLinus Torvalds return error; 43231da177e4SLinus Torvalds 43242773bf00SMiklos Szeredi if (!old_dir->i_op->rename) 43251da177e4SLinus Torvalds return -EPERM; 43261da177e4SLinus Torvalds 4327bc27027aSMiklos Szeredi /* 4328bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4329bc27027aSMiklos Szeredi * we'll need to flip '..'. 4330bc27027aSMiklos Szeredi */ 4331da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4332da1ce067SMiklos Szeredi if (is_dir) { 4333bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4334bc27027aSMiklos Szeredi if (error) 4335bc27027aSMiklos Szeredi return error; 4336bc27027aSMiklos Szeredi } 4337da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4338da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4339da1ce067SMiklos Szeredi if (error) 4340da1ce067SMiklos Szeredi return error; 4341da1ce067SMiklos Szeredi } 4342da1ce067SMiklos Szeredi } 43430eeca283SRobert Love 43440b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 43450b3974ebSMiklos Szeredi flags); 4346bc27027aSMiklos Szeredi if (error) 4347bc27027aSMiklos Szeredi return error; 4348bc27027aSMiklos Szeredi 434949d31c2fSAl Viro take_dentry_name_snapshot(&old_name, old_dentry); 4350bc27027aSMiklos Szeredi dget(new_dentry); 4351da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4352bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4353bc27027aSMiklos Szeredi else if (target) 43545955102cSAl Viro inode_lock(target); 4355bc27027aSMiklos Szeredi 4356bc27027aSMiklos Szeredi error = -EBUSY; 43577af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4358bc27027aSMiklos Szeredi goto out; 4359bc27027aSMiklos Szeredi 4360da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4361bc27027aSMiklos Szeredi error = -EMLINK; 4362da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4363bc27027aSMiklos Szeredi goto out; 4364da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4365da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4366da1ce067SMiklos Szeredi goto out; 4367da1ce067SMiklos Szeredi } 4368da1ce067SMiklos Szeredi if (!is_dir) { 4369bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4370bc27027aSMiklos Szeredi if (error) 4371bc27027aSMiklos Szeredi goto out; 4372da1ce067SMiklos Szeredi } 4373da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4374bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4375bc27027aSMiklos Szeredi if (error) 4376bc27027aSMiklos Szeredi goto out; 4377bc27027aSMiklos Szeredi } 4378520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4379520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4380bc27027aSMiklos Szeredi if (error) 4381bc27027aSMiklos Szeredi goto out; 4382bc27027aSMiklos Szeredi 4383da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 43848767712fSAl Viro if (is_dir) { 43858767712fSAl Viro shrink_dcache_parent(new_dentry); 4386bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 43878767712fSAl Viro } 4388bc27027aSMiklos Szeredi dont_mount(new_dentry); 43898ed936b5SEric W. Biederman detach_mounts(new_dentry); 4390bc27027aSMiklos Szeredi } 4391da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4392da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4393bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4394da1ce067SMiklos Szeredi else 4395da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4396da1ce067SMiklos Szeredi } 4397bc27027aSMiklos Szeredi out: 4398da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4399bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4400bc27027aSMiklos Szeredi else if (target) 44015955102cSAl Viro inode_unlock(target); 4402bc27027aSMiklos Szeredi dput(new_dentry); 4403da1ce067SMiklos Szeredi if (!error) { 4404f4ec3a3dSAl Viro fsnotify_move(old_dir, new_dir, &old_name.name, is_dir, 4405da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4406da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4407f4ec3a3dSAl Viro fsnotify_move(new_dir, old_dir, &old_dentry->d_name, 4408da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4409da1ce067SMiklos Szeredi } 4410da1ce067SMiklos Szeredi } 441149d31c2fSAl Viro release_dentry_name_snapshot(&old_name); 44120eeca283SRobert Love 44131da177e4SLinus Torvalds return error; 44141da177e4SLinus Torvalds } 44154d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 44161da177e4SLinus Torvalds 4417ee81feb6SDominik Brodowski static int do_renameat2(int olddfd, const char __user *oldname, int newdfd, 4418ee81feb6SDominik Brodowski const char __user *newname, unsigned int flags) 44191da177e4SLinus Torvalds { 44201da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 44211da177e4SLinus Torvalds struct dentry *trap; 4422f5beed75SAl Viro struct path old_path, new_path; 4423f5beed75SAl Viro struct qstr old_last, new_last; 4424f5beed75SAl Viro int old_type, new_type; 44258e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 442691a27b2aSJeff Layton struct filename *from; 442791a27b2aSJeff Layton struct filename *to; 4428f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4429c6a94284SJeff Layton bool should_retry = false; 44302ad94ae6SAl Viro int error; 4431520c8b16SMiklos Szeredi 44320d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4433da1ce067SMiklos Szeredi return -EINVAL; 4434da1ce067SMiklos Szeredi 44350d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 44360d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4437520c8b16SMiklos Szeredi return -EINVAL; 4438520c8b16SMiklos Szeredi 44390d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 44400d7a8555SMiklos Szeredi return -EPERM; 44410d7a8555SMiklos Szeredi 4442f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4443f5beed75SAl Viro target_flags = 0; 4444f5beed75SAl Viro 4445c6a94284SJeff Layton retry: 4446c1d4dd27SAl Viro from = filename_parentat(olddfd, getname(oldname), lookup_flags, 4447c1d4dd27SAl Viro &old_path, &old_last, &old_type); 444891a27b2aSJeff Layton if (IS_ERR(from)) { 444991a27b2aSJeff Layton error = PTR_ERR(from); 44501da177e4SLinus Torvalds goto exit; 445191a27b2aSJeff Layton } 44521da177e4SLinus Torvalds 4453c1d4dd27SAl Viro to = filename_parentat(newdfd, getname(newname), lookup_flags, 4454c1d4dd27SAl Viro &new_path, &new_last, &new_type); 445591a27b2aSJeff Layton if (IS_ERR(to)) { 445691a27b2aSJeff Layton error = PTR_ERR(to); 44571da177e4SLinus Torvalds goto exit1; 445891a27b2aSJeff Layton } 44591da177e4SLinus Torvalds 44601da177e4SLinus Torvalds error = -EXDEV; 4461f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 44621da177e4SLinus Torvalds goto exit2; 44631da177e4SLinus Torvalds 44641da177e4SLinus Torvalds error = -EBUSY; 4465f5beed75SAl Viro if (old_type != LAST_NORM) 44661da177e4SLinus Torvalds goto exit2; 44671da177e4SLinus Torvalds 44680a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 44690a7c3937SMiklos Szeredi error = -EEXIST; 4470f5beed75SAl Viro if (new_type != LAST_NORM) 44711da177e4SLinus Torvalds goto exit2; 44721da177e4SLinus Torvalds 4473f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4474c30dabfeSJan Kara if (error) 4475c30dabfeSJan Kara goto exit2; 4476c30dabfeSJan Kara 44778e6d782cSJ. Bruce Fields retry_deleg: 4478f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 44791da177e4SLinus Torvalds 4480f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 44811da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 44821da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 44831da177e4SLinus Torvalds goto exit3; 44841da177e4SLinus Torvalds /* source must exist */ 44851da177e4SLinus Torvalds error = -ENOENT; 4486b18825a7SDavid Howells if (d_is_negative(old_dentry)) 44871da177e4SLinus Torvalds goto exit4; 4488f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 44891da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 44901da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 44911da177e4SLinus Torvalds goto exit4; 44920a7c3937SMiklos Szeredi error = -EEXIST; 44930a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 44940a7c3937SMiklos Szeredi goto exit5; 4495da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4496da1ce067SMiklos Szeredi error = -ENOENT; 4497da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4498da1ce067SMiklos Szeredi goto exit5; 4499da1ce067SMiklos Szeredi 4500da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4501da1ce067SMiklos Szeredi error = -ENOTDIR; 4502f5beed75SAl Viro if (new_last.name[new_last.len]) 4503da1ce067SMiklos Szeredi goto exit5; 4504da1ce067SMiklos Szeredi } 4505da1ce067SMiklos Szeredi } 45060a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 45070a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 45080a7c3937SMiklos Szeredi error = -ENOTDIR; 4509f5beed75SAl Viro if (old_last.name[old_last.len]) 45100a7c3937SMiklos Szeredi goto exit5; 4511f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 45120a7c3937SMiklos Szeredi goto exit5; 45130a7c3937SMiklos Szeredi } 45140a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 45150a7c3937SMiklos Szeredi error = -EINVAL; 45160a7c3937SMiklos Szeredi if (old_dentry == trap) 45170a7c3937SMiklos Szeredi goto exit5; 45181da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4519da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 45201da177e4SLinus Torvalds error = -ENOTEMPTY; 45211da177e4SLinus Torvalds if (new_dentry == trap) 45221da177e4SLinus Torvalds goto exit5; 45231da177e4SLinus Torvalds 4524f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4525f5beed75SAl Viro &new_path, new_dentry, flags); 4526be6d3e56SKentaro Takeda if (error) 4527c30dabfeSJan Kara goto exit5; 4528f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4529f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4530520c8b16SMiklos Szeredi &delegated_inode, flags); 45311da177e4SLinus Torvalds exit5: 45321da177e4SLinus Torvalds dput(new_dentry); 45331da177e4SLinus Torvalds exit4: 45341da177e4SLinus Torvalds dput(old_dentry); 45351da177e4SLinus Torvalds exit3: 4536f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 45378e6d782cSJ. Bruce Fields if (delegated_inode) { 45388e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 45398e6d782cSJ. Bruce Fields if (!error) 45408e6d782cSJ. Bruce Fields goto retry_deleg; 45418e6d782cSJ. Bruce Fields } 4542f5beed75SAl Viro mnt_drop_write(old_path.mnt); 45431da177e4SLinus Torvalds exit2: 4544c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4545c6a94284SJeff Layton should_retry = true; 4546f5beed75SAl Viro path_put(&new_path); 45472ad94ae6SAl Viro putname(to); 45481da177e4SLinus Torvalds exit1: 4549f5beed75SAl Viro path_put(&old_path); 45501da177e4SLinus Torvalds putname(from); 4551c6a94284SJeff Layton if (should_retry) { 4552c6a94284SJeff Layton should_retry = false; 4553c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4554c6a94284SJeff Layton goto retry; 4555c6a94284SJeff Layton } 45562ad94ae6SAl Viro exit: 45571da177e4SLinus Torvalds return error; 45581da177e4SLinus Torvalds } 45591da177e4SLinus Torvalds 4560ee81feb6SDominik Brodowski SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4561ee81feb6SDominik Brodowski int, newdfd, const char __user *, newname, unsigned int, flags) 4562ee81feb6SDominik Brodowski { 4563ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, flags); 4564ee81feb6SDominik Brodowski } 4565ee81feb6SDominik Brodowski 4566520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4567520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4568520c8b16SMiklos Szeredi { 4569ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, 0); 4570520c8b16SMiklos Szeredi } 4571520c8b16SMiklos Szeredi 4572a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 45735590ff0dSUlrich Drepper { 4574ee81feb6SDominik Brodowski return do_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 45755590ff0dSUlrich Drepper } 45765590ff0dSUlrich Drepper 4577787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4578787fb6bcSMiklos Szeredi { 4579787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4580787fb6bcSMiklos Szeredi if (error) 4581787fb6bcSMiklos Szeredi return error; 4582787fb6bcSMiklos Szeredi 4583787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4584787fb6bcSMiklos Szeredi return -EPERM; 4585787fb6bcSMiklos Szeredi 4586787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4587787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4588787fb6bcSMiklos Szeredi } 4589787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4590787fb6bcSMiklos Szeredi 45915d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 45921da177e4SLinus Torvalds { 45935d826c84SAl Viro int len = PTR_ERR(link); 45941da177e4SLinus Torvalds if (IS_ERR(link)) 45951da177e4SLinus Torvalds goto out; 45961da177e4SLinus Torvalds 45971da177e4SLinus Torvalds len = strlen(link); 45981da177e4SLinus Torvalds if (len > (unsigned) buflen) 45991da177e4SLinus Torvalds len = buflen; 46001da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 46011da177e4SLinus Torvalds len = -EFAULT; 46021da177e4SLinus Torvalds out: 46031da177e4SLinus Torvalds return len; 46041da177e4SLinus Torvalds } 46051da177e4SLinus Torvalds 4606d60874cdSMiklos Szeredi /** 4607fd4a0edfSMiklos Szeredi * vfs_readlink - copy symlink body into userspace buffer 4608fd4a0edfSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4609fd4a0edfSMiklos Szeredi * @buffer: user memory pointer 4610fd4a0edfSMiklos Szeredi * @buflen: size of buffer 4611fd4a0edfSMiklos Szeredi * 4612fd4a0edfSMiklos Szeredi * Does not touch atime. That's up to the caller if necessary 4613fd4a0edfSMiklos Szeredi * 4614fd4a0edfSMiklos Szeredi * Does not call security hook. 4615fd4a0edfSMiklos Szeredi */ 4616fd4a0edfSMiklos Szeredi int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4617fd4a0edfSMiklos Szeredi { 4618fd4a0edfSMiklos Szeredi struct inode *inode = d_inode(dentry); 4619f2df5da6SAl Viro DEFINE_DELAYED_CALL(done); 4620f2df5da6SAl Viro const char *link; 4621f2df5da6SAl Viro int res; 4622fd4a0edfSMiklos Szeredi 462376fca90eSMiklos Szeredi if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) { 462476fca90eSMiklos Szeredi if (unlikely(inode->i_op->readlink)) 462576fca90eSMiklos Szeredi return inode->i_op->readlink(dentry, buffer, buflen); 462676fca90eSMiklos Szeredi 462776fca90eSMiklos Szeredi if (!d_is_symlink(dentry)) 4628fd4a0edfSMiklos Szeredi return -EINVAL; 4629fd4a0edfSMiklos Szeredi 463076fca90eSMiklos Szeredi spin_lock(&inode->i_lock); 463176fca90eSMiklos Szeredi inode->i_opflags |= IOP_DEFAULT_READLINK; 463276fca90eSMiklos Szeredi spin_unlock(&inode->i_lock); 463376fca90eSMiklos Szeredi } 463476fca90eSMiklos Szeredi 46354c4f7c19SEric Biggers link = READ_ONCE(inode->i_link); 4636f2df5da6SAl Viro if (!link) { 4637f2df5da6SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4638f2df5da6SAl Viro if (IS_ERR(link)) 4639f2df5da6SAl Viro return PTR_ERR(link); 4640f2df5da6SAl Viro } 4641f2df5da6SAl Viro res = readlink_copy(buffer, buflen, link); 4642f2df5da6SAl Viro do_delayed_call(&done); 4643f2df5da6SAl Viro return res; 4644fd4a0edfSMiklos Szeredi } 4645fd4a0edfSMiklos Szeredi EXPORT_SYMBOL(vfs_readlink); 46461da177e4SLinus Torvalds 4647d60874cdSMiklos Szeredi /** 4648d60874cdSMiklos Szeredi * vfs_get_link - get symlink body 4649d60874cdSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4650d60874cdSMiklos Szeredi * @done: caller needs to free returned data with this 4651d60874cdSMiklos Szeredi * 4652d60874cdSMiklos Szeredi * Calls security hook and i_op->get_link() on the supplied inode. 4653d60874cdSMiklos Szeredi * 4654d60874cdSMiklos Szeredi * It does not touch atime. That's up to the caller if necessary. 4655d60874cdSMiklos Szeredi * 4656d60874cdSMiklos Szeredi * Does not work on "special" symlinks like /proc/$$/fd/N 4657d60874cdSMiklos Szeredi */ 4658d60874cdSMiklos Szeredi const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done) 4659d60874cdSMiklos Szeredi { 4660d60874cdSMiklos Szeredi const char *res = ERR_PTR(-EINVAL); 4661d60874cdSMiklos Szeredi struct inode *inode = d_inode(dentry); 4662d60874cdSMiklos Szeredi 4663d60874cdSMiklos Szeredi if (d_is_symlink(dentry)) { 4664d60874cdSMiklos Szeredi res = ERR_PTR(security_inode_readlink(dentry)); 4665d60874cdSMiklos Szeredi if (!res) 4666d60874cdSMiklos Szeredi res = inode->i_op->get_link(dentry, inode, done); 4667d60874cdSMiklos Szeredi } 4668d60874cdSMiklos Szeredi return res; 4669d60874cdSMiklos Szeredi } 4670d60874cdSMiklos Szeredi EXPORT_SYMBOL(vfs_get_link); 4671d60874cdSMiklos Szeredi 46721da177e4SLinus Torvalds /* get the link contents into pagecache */ 46736b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4674fceef393SAl Viro struct delayed_call *callback) 46751da177e4SLinus Torvalds { 4676ebd09abbSDuane Griffin char *kaddr; 46771da177e4SLinus Torvalds struct page *page; 46786b255391SAl Viro struct address_space *mapping = inode->i_mapping; 46796b255391SAl Viro 4680d3883d4fSAl Viro if (!dentry) { 4681d3883d4fSAl Viro page = find_get_page(mapping, 0); 4682d3883d4fSAl Viro if (!page) 46836b255391SAl Viro return ERR_PTR(-ECHILD); 4684d3883d4fSAl Viro if (!PageUptodate(page)) { 4685d3883d4fSAl Viro put_page(page); 4686d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4687d3883d4fSAl Viro } 4688d3883d4fSAl Viro } else { 4689090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 46901da177e4SLinus Torvalds if (IS_ERR(page)) 46916fe6900eSNick Piggin return (char*)page; 4692d3883d4fSAl Viro } 4693fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 469421fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 469521fc61c7SAl Viro kaddr = page_address(page); 46966b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4697ebd09abbSDuane Griffin return kaddr; 46981da177e4SLinus Torvalds } 46991da177e4SLinus Torvalds 47006b255391SAl Viro EXPORT_SYMBOL(page_get_link); 47011da177e4SLinus Torvalds 4702fceef393SAl Viro void page_put_link(void *arg) 47031da177e4SLinus Torvalds { 4704fceef393SAl Viro put_page(arg); 47051da177e4SLinus Torvalds } 47064d359507SAl Viro EXPORT_SYMBOL(page_put_link); 47071da177e4SLinus Torvalds 4708aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4709aa80deabSAl Viro { 4710fceef393SAl Viro DEFINE_DELAYED_CALL(done); 47116b255391SAl Viro int res = readlink_copy(buffer, buflen, 47126b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4713fceef393SAl Viro &done)); 4714fceef393SAl Viro do_delayed_call(&done); 4715aa80deabSAl Viro return res; 4716aa80deabSAl Viro } 4717aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4718aa80deabSAl Viro 471954566b2cSNick Piggin /* 472054566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 472154566b2cSNick Piggin */ 472254566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 47231da177e4SLinus Torvalds { 47241da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 47250adb25d2SKirill Korotaev struct page *page; 4726afddba49SNick Piggin void *fsdata; 4727beb497abSDmitriy Monakhov int err; 4728c718a975STetsuo Handa unsigned int flags = 0; 472954566b2cSNick Piggin if (nofs) 473054566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 47311da177e4SLinus Torvalds 47327e53cac4SNeilBrown retry: 4733afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 473454566b2cSNick Piggin flags, &page, &fsdata); 47351da177e4SLinus Torvalds if (err) 4736afddba49SNick Piggin goto fail; 4737afddba49SNick Piggin 473821fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4739afddba49SNick Piggin 4740afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4741afddba49SNick Piggin page, fsdata); 47421da177e4SLinus Torvalds if (err < 0) 47431da177e4SLinus Torvalds goto fail; 4744afddba49SNick Piggin if (err < len-1) 4745afddba49SNick Piggin goto retry; 4746afddba49SNick Piggin 47471da177e4SLinus Torvalds mark_inode_dirty(inode); 47481da177e4SLinus Torvalds return 0; 47491da177e4SLinus Torvalds fail: 47501da177e4SLinus Torvalds return err; 47511da177e4SLinus Torvalds } 47524d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 47531da177e4SLinus Torvalds 47540adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 47550adb25d2SKirill Korotaev { 47560adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4757c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 47580adb25d2SKirill Korotaev } 47594d359507SAl Viro EXPORT_SYMBOL(page_symlink); 47600adb25d2SKirill Korotaev 476192e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 47626b255391SAl Viro .get_link = page_get_link, 47631da177e4SLinus Torvalds }; 47641da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4765