11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namei.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Some corrections by tytso. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 121da177e4SLinus Torvalds * lookup logic. 131da177e4SLinus Torvalds */ 141da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 151da177e4SLinus Torvalds */ 161da177e4SLinus Torvalds 171da177e4SLinus Torvalds #include <linux/init.h> 18630d9c47SPaul Gortmaker #include <linux/export.h> 1944696908SDavid S. Miller #include <linux/kernel.h> 201da177e4SLinus Torvalds #include <linux/slab.h> 211da177e4SLinus Torvalds #include <linux/fs.h> 221da177e4SLinus Torvalds #include <linux/namei.h> 231da177e4SLinus Torvalds #include <linux/pagemap.h> 240eeca283SRobert Love #include <linux/fsnotify.h> 251da177e4SLinus Torvalds #include <linux/personality.h> 261da177e4SLinus Torvalds #include <linux/security.h> 276146f0d5SMimi Zohar #include <linux/ima.h> 281da177e4SLinus Torvalds #include <linux/syscalls.h> 291da177e4SLinus Torvalds #include <linux/mount.h> 301da177e4SLinus Torvalds #include <linux/audit.h> 3116f7e0feSRandy Dunlap #include <linux/capability.h> 32834f2a4aSTrond Myklebust #include <linux/file.h> 335590ff0dSUlrich Drepper #include <linux/fcntl.h> 3408ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 355ad4e53bSAl Viro #include <linux/fs_struct.h> 36e77819e5SLinus Torvalds #include <linux/posix_acl.h> 3799d263d4SLinus Torvalds #include <linux/hash.h> 382a18da7aSGeorge Spelvin #include <linux/bitops.h> 39aeaa4a79SEric W. Biederman #include <linux/init_task.h> 407c0f6ba6SLinus Torvalds #include <linux/uaccess.h> 411da177e4SLinus Torvalds 42e81e3f4dSEric Paris #include "internal.h" 43c7105365SAl Viro #include "mount.h" 44e81e3f4dSEric Paris 451da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 461da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 471da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 481da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 491da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 501da177e4SLinus Torvalds * 511da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 521da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 531da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 541da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 551da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 561da177e4SLinus Torvalds * the special cases of the former code. 571da177e4SLinus Torvalds * 581da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 591da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 601da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 611da177e4SLinus Torvalds * 621da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 631da177e4SLinus Torvalds * resolution to correspond with current state of the code. 641da177e4SLinus Torvalds * 651da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 661da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 671da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 681da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 691da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 701da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 711da177e4SLinus Torvalds */ 721da177e4SLinus Torvalds 731da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 741da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 751da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 761da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 771da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 781da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7925985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 801da177e4SLinus Torvalds * 811da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 821da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 831da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 841da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 851da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 861da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 871da177e4SLinus Torvalds * and in the old Linux semantics. 881da177e4SLinus Torvalds */ 891da177e4SLinus Torvalds 901da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 911da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 921da177e4SLinus Torvalds * 931da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 941da177e4SLinus Torvalds */ 951da177e4SLinus Torvalds 961da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 971da177e4SLinus Torvalds * inside the path - always follow. 981da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 991da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 1001da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 1011da177e4SLinus Torvalds * otherwise - don't follow. 1021da177e4SLinus Torvalds * (applied in that order). 1031da177e4SLinus Torvalds * 1041da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1051da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1061da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1071da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1081da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1091da177e4SLinus Torvalds */ 1101da177e4SLinus Torvalds /* 1111da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 112a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1131da177e4SLinus Torvalds * any extra contention... 1141da177e4SLinus Torvalds */ 1151da177e4SLinus Torvalds 1161da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1171da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1181da177e4SLinus Torvalds * kernel data space before using them.. 1191da177e4SLinus Torvalds * 1201da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1211da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1221da177e4SLinus Torvalds */ 1237950e385SJeff Layton 124fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12591a27b2aSJeff Layton 12651f39a1fSDavid Drysdale struct filename * 12791a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12891a27b2aSJeff Layton { 12994b5d262SAl Viro struct filename *result; 1307950e385SJeff Layton char *kname; 13194b5d262SAl Viro int len; 1321da177e4SLinus Torvalds 1337ac86265SJeff Layton result = audit_reusename(filename); 1347ac86265SJeff Layton if (result) 1357ac86265SJeff Layton return result; 1367ac86265SJeff Layton 1377950e385SJeff Layton result = __getname(); 1383f9f0aa6SLinus Torvalds if (unlikely(!result)) 1394043cde8SEric Paris return ERR_PTR(-ENOMEM); 1401da177e4SLinus Torvalds 1417950e385SJeff Layton /* 1427950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1437950e385SJeff Layton * allocation 1447950e385SJeff Layton */ 145fd2f7cb5SAl Viro kname = (char *)result->iname; 14691a27b2aSJeff Layton result->name = kname; 1477950e385SJeff Layton 14894b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 14991a27b2aSJeff Layton if (unlikely(len < 0)) { 15094b5d262SAl Viro __putname(result); 15194b5d262SAl Viro return ERR_PTR(len); 15291a27b2aSJeff Layton } 1533f9f0aa6SLinus Torvalds 1547950e385SJeff Layton /* 1557950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1567950e385SJeff Layton * separate struct filename so we can dedicate the entire 1577950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1587950e385SJeff Layton * userland. 1597950e385SJeff Layton */ 16094b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 161fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1627950e385SJeff Layton kname = (char *)result; 1637950e385SJeff Layton 164fd2f7cb5SAl Viro /* 165fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 166fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 167fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 168fd2f7cb5SAl Viro */ 169fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 17094b5d262SAl Viro if (unlikely(!result)) { 17194b5d262SAl Viro __putname(kname); 17294b5d262SAl Viro return ERR_PTR(-ENOMEM); 1737950e385SJeff Layton } 1747950e385SJeff Layton result->name = kname; 17594b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17694b5d262SAl Viro if (unlikely(len < 0)) { 17794b5d262SAl Viro __putname(kname); 17894b5d262SAl Viro kfree(result); 17994b5d262SAl Viro return ERR_PTR(len); 18094b5d262SAl Viro } 18194b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18294b5d262SAl Viro __putname(kname); 18394b5d262SAl Viro kfree(result); 18494b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18594b5d262SAl Viro } 1867950e385SJeff Layton } 1877950e385SJeff Layton 18894b5d262SAl Viro result->refcnt = 1; 1893f9f0aa6SLinus Torvalds /* The empty path is special. */ 1903f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1913f9f0aa6SLinus Torvalds if (empty) 1921fa1e7f6SAndy Whitcroft *empty = 1; 19394b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19494b5d262SAl Viro putname(result); 19594b5d262SAl Viro return ERR_PTR(-ENOENT); 1961da177e4SLinus Torvalds } 19794b5d262SAl Viro } 1987950e385SJeff Layton 1997950e385SJeff Layton result->uptr = filename; 200c4ad8f98SLinus Torvalds result->aname = NULL; 2011da177e4SLinus Torvalds audit_getname(result); 2021da177e4SLinus Torvalds return result; 2033f9f0aa6SLinus Torvalds } 2043f9f0aa6SLinus Torvalds 20591a27b2aSJeff Layton struct filename * 20691a27b2aSJeff Layton getname(const char __user * filename) 207f52e0c11SAl Viro { 208f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 209f52e0c11SAl Viro } 210f52e0c11SAl Viro 211c4ad8f98SLinus Torvalds struct filename * 212c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 213c4ad8f98SLinus Torvalds { 214c4ad8f98SLinus Torvalds struct filename *result; 21508518549SPaul Moore int len = strlen(filename) + 1; 216c4ad8f98SLinus Torvalds 217c4ad8f98SLinus Torvalds result = __getname(); 218c4ad8f98SLinus Torvalds if (unlikely(!result)) 219c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 220c4ad8f98SLinus Torvalds 22108518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 222fd2f7cb5SAl Viro result->name = (char *)result->iname; 22308518549SPaul Moore } else if (len <= PATH_MAX) { 22408518549SPaul Moore struct filename *tmp; 22508518549SPaul Moore 22608518549SPaul Moore tmp = kmalloc(sizeof(*tmp), GFP_KERNEL); 22708518549SPaul Moore if (unlikely(!tmp)) { 22808518549SPaul Moore __putname(result); 22908518549SPaul Moore return ERR_PTR(-ENOMEM); 23008518549SPaul Moore } 23108518549SPaul Moore tmp->name = (char *)result; 23208518549SPaul Moore result = tmp; 23308518549SPaul Moore } else { 23408518549SPaul Moore __putname(result); 23508518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23608518549SPaul Moore } 23708518549SPaul Moore memcpy((char *)result->name, filename, len); 238c4ad8f98SLinus Torvalds result->uptr = NULL; 239c4ad8f98SLinus Torvalds result->aname = NULL; 24055422d0bSPaul Moore result->refcnt = 1; 241fd3522fdSPaul Moore audit_getname(result); 242c4ad8f98SLinus Torvalds 243c4ad8f98SLinus Torvalds return result; 244c4ad8f98SLinus Torvalds } 245c4ad8f98SLinus Torvalds 24691a27b2aSJeff Layton void putname(struct filename *name) 2471da177e4SLinus Torvalds { 24855422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 24955422d0bSPaul Moore 25055422d0bSPaul Moore if (--name->refcnt > 0) 25155422d0bSPaul Moore return; 25255422d0bSPaul Moore 253fd2f7cb5SAl Viro if (name->name != name->iname) { 25455422d0bSPaul Moore __putname(name->name); 25555422d0bSPaul Moore kfree(name); 25655422d0bSPaul Moore } else 25755422d0bSPaul Moore __putname(name); 2581da177e4SLinus Torvalds } 2591da177e4SLinus Torvalds 260e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 261e77819e5SLinus Torvalds { 26284635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 263e77819e5SLinus Torvalds struct posix_acl *acl; 264e77819e5SLinus Torvalds 265e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2663567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2673567866bSAl Viro if (!acl) 268e77819e5SLinus Torvalds return -EAGAIN; 2693567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 270b8a7a3a6SAndreas Gruenbacher if (is_uncached_acl(acl)) 271e77819e5SLinus Torvalds return -ECHILD; 272206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 273e77819e5SLinus Torvalds } 274e77819e5SLinus Torvalds 2752982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2764e34e719SChristoph Hellwig if (IS_ERR(acl)) 2774e34e719SChristoph Hellwig return PTR_ERR(acl); 278e77819e5SLinus Torvalds if (acl) { 279e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 280e77819e5SLinus Torvalds posix_acl_release(acl); 281e77819e5SLinus Torvalds return error; 282e77819e5SLinus Torvalds } 28384635d68SLinus Torvalds #endif 284e77819e5SLinus Torvalds 285e77819e5SLinus Torvalds return -EAGAIN; 286e77819e5SLinus Torvalds } 287e77819e5SLinus Torvalds 2885909ccaaSLinus Torvalds /* 289948409c7SAndreas Gruenbacher * This does the basic permission checking 2905909ccaaSLinus Torvalds */ 2917e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2925909ccaaSLinus Torvalds { 29326cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2945909ccaaSLinus Torvalds 2958e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2965909ccaaSLinus Torvalds mode >>= 6; 2975909ccaaSLinus Torvalds else { 298e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2997e40145eSAl Viro int error = check_acl(inode, mask); 3005909ccaaSLinus Torvalds if (error != -EAGAIN) 3015909ccaaSLinus Torvalds return error; 3025909ccaaSLinus Torvalds } 3035909ccaaSLinus Torvalds 3045909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3055909ccaaSLinus Torvalds mode >>= 3; 3065909ccaaSLinus Torvalds } 3075909ccaaSLinus Torvalds 3085909ccaaSLinus Torvalds /* 3095909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3105909ccaaSLinus Torvalds */ 3119c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3125909ccaaSLinus Torvalds return 0; 3135909ccaaSLinus Torvalds return -EACCES; 3145909ccaaSLinus Torvalds } 3151da177e4SLinus Torvalds 3161da177e4SLinus Torvalds /** 3171da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3181da177e4SLinus Torvalds * @inode: inode to check access rights for 3198fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3201da177e4SLinus Torvalds * 3211da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3221da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3231da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 324b74c79e9SNick Piggin * are used for other things. 325b74c79e9SNick Piggin * 326b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 327b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 328b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3291da177e4SLinus Torvalds */ 3302830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3311da177e4SLinus Torvalds { 3325909ccaaSLinus Torvalds int ret; 3331da177e4SLinus Torvalds 3341da177e4SLinus Torvalds /* 335948409c7SAndreas Gruenbacher * Do the basic permission checks. 3361da177e4SLinus Torvalds */ 3377e40145eSAl Viro ret = acl_permission_check(inode, mask); 3385909ccaaSLinus Torvalds if (ret != -EACCES) 3395909ccaaSLinus Torvalds return ret; 3401da177e4SLinus Torvalds 341d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 342d594e7ecSAl Viro /* DACs are overridable for directories */ 343d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34423adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34523adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 346d594e7ecSAl Viro return 0; 34723adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3481da177e4SLinus Torvalds return 0; 3492a4c2242SStephen Smalley return -EACCES; 3502a4c2242SStephen Smalley } 3511da177e4SLinus Torvalds 3521da177e4SLinus Torvalds /* 3531da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3541da177e4SLinus Torvalds */ 3557ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 356d594e7ecSAl Viro if (mask == MAY_READ) 35723adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3581da177e4SLinus Torvalds return 0; 3592a4c2242SStephen Smalley /* 3602a4c2242SStephen Smalley * Read/write DACs are always overridable. 3612a4c2242SStephen Smalley * Executable DACs are overridable when there is 3622a4c2242SStephen Smalley * at least one exec bit set. 3632a4c2242SStephen Smalley */ 3642a4c2242SStephen Smalley if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 3652a4c2242SStephen Smalley if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3662a4c2242SStephen Smalley return 0; 3671da177e4SLinus Torvalds 3681da177e4SLinus Torvalds return -EACCES; 3691da177e4SLinus Torvalds } 3704d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3711da177e4SLinus Torvalds 3723ddcd056SLinus Torvalds /* 3733ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3743ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3753ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3763ddcd056SLinus Torvalds * permission function, use the fast case". 3773ddcd056SLinus Torvalds */ 3783ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3793ddcd056SLinus Torvalds { 3803ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3813ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3823ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3833ddcd056SLinus Torvalds 3843ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3853ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3863ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3873ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3883ddcd056SLinus Torvalds } 3893ddcd056SLinus Torvalds return generic_permission(inode, mask); 3903ddcd056SLinus Torvalds } 3913ddcd056SLinus Torvalds 392cb23beb5SChristoph Hellwig /** 3930bdaea90SDavid Howells * __inode_permission - Check for access rights to a given inode 3940bdaea90SDavid Howells * @inode: Inode to check permission on 3950bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 396cb23beb5SChristoph Hellwig * 3970bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. 398948409c7SAndreas Gruenbacher * 399948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4000bdaea90SDavid Howells * 4010bdaea90SDavid Howells * This does not check for a read-only file system. You probably want 4020bdaea90SDavid Howells * inode_permission(). 403cb23beb5SChristoph Hellwig */ 4040bdaea90SDavid Howells int __inode_permission(struct inode *inode, int mask) 4051da177e4SLinus Torvalds { 406e6305c43SAl Viro int retval; 4071da177e4SLinus Torvalds 4083ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 4091da177e4SLinus Torvalds /* 4101da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 4111da177e4SLinus Torvalds */ 4121da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 413337684a1SEryu Guan return -EPERM; 4140bd23d09SEric W. Biederman 4150bd23d09SEric W. Biederman /* 4160bd23d09SEric W. Biederman * Updating mtime will likely cause i_uid and i_gid to be 4170bd23d09SEric W. Biederman * written back improperly if their true value is unknown 4180bd23d09SEric W. Biederman * to the vfs. 4190bd23d09SEric W. Biederman */ 4200bd23d09SEric W. Biederman if (HAS_UNMAPPED_ID(inode)) 4210bd23d09SEric W. Biederman return -EACCES; 4221da177e4SLinus Torvalds } 4231da177e4SLinus Torvalds 4243ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 4251da177e4SLinus Torvalds if (retval) 4261da177e4SLinus Torvalds return retval; 4271da177e4SLinus Torvalds 42808ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 42908ce5f16SSerge E. Hallyn if (retval) 43008ce5f16SSerge E. Hallyn return retval; 43108ce5f16SSerge E. Hallyn 432d09ca739SEric Paris return security_inode_permission(inode, mask); 4331da177e4SLinus Torvalds } 434bd5d0856SMiklos Szeredi EXPORT_SYMBOL(__inode_permission); 4351da177e4SLinus Torvalds 436f4d6ff89SAl Viro /** 4370bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 4380bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 43955852635SRandy Dunlap * @inode: Inode to check permission on 4400bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4410bdaea90SDavid Howells * 4420bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4430bdaea90SDavid Howells */ 4440bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4450bdaea90SDavid Howells { 4460bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4470bdaea90SDavid Howells umode_t mode = inode->i_mode; 4480bdaea90SDavid Howells 4490bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 450bc98a42cSDavid Howells if (sb_rdonly(sb) && (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4510bdaea90SDavid Howells return -EROFS; 4520bdaea90SDavid Howells } 4530bdaea90SDavid Howells return 0; 4540bdaea90SDavid Howells } 4550bdaea90SDavid Howells 4560bdaea90SDavid Howells /** 4570bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4580bdaea90SDavid Howells * @inode: Inode to check permission on 4590bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4600bdaea90SDavid Howells * 4610bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4620bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4630bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4640bdaea90SDavid Howells * 4650bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4660bdaea90SDavid Howells */ 4670bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4680bdaea90SDavid Howells { 4690bdaea90SDavid Howells int retval; 4700bdaea90SDavid Howells 4710bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4720bdaea90SDavid Howells if (retval) 4730bdaea90SDavid Howells return retval; 4740bdaea90SDavid Howells return __inode_permission(inode, mask); 4750bdaea90SDavid Howells } 4764d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4770bdaea90SDavid Howells 4780bdaea90SDavid Howells /** 4795dd784d0SJan Blunck * path_get - get a reference to a path 4805dd784d0SJan Blunck * @path: path to get the reference to 4815dd784d0SJan Blunck * 4825dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4835dd784d0SJan Blunck */ 484dcf787f3SAl Viro void path_get(const struct path *path) 4855dd784d0SJan Blunck { 4865dd784d0SJan Blunck mntget(path->mnt); 4875dd784d0SJan Blunck dget(path->dentry); 4885dd784d0SJan Blunck } 4895dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4905dd784d0SJan Blunck 4915dd784d0SJan Blunck /** 4921d957f9bSJan Blunck * path_put - put a reference to a path 4931d957f9bSJan Blunck * @path: path to put the reference to 4941d957f9bSJan Blunck * 4951d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4961d957f9bSJan Blunck */ 497dcf787f3SAl Viro void path_put(const struct path *path) 4981da177e4SLinus Torvalds { 4991d957f9bSJan Blunck dput(path->dentry); 5001d957f9bSJan Blunck mntput(path->mnt); 5011da177e4SLinus Torvalds } 5021d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 5031da177e4SLinus Torvalds 504894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 5051f55a6ecSAl Viro struct nameidata { 5061f55a6ecSAl Viro struct path path; 5071f55a6ecSAl Viro struct qstr last; 5081f55a6ecSAl Viro struct path root; 5091f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 5101f55a6ecSAl Viro unsigned int flags; 5119883d185SAl Viro unsigned seq, m_seq; 5121f55a6ecSAl Viro int last_type; 5131f55a6ecSAl Viro unsigned depth; 514756daf26SNeilBrown int total_link_count; 515697fc6caSAl Viro struct saved { 516697fc6caSAl Viro struct path link; 517fceef393SAl Viro struct delayed_call done; 518697fc6caSAl Viro const char *name; 5190450b2d1SAl Viro unsigned seq; 520894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5219883d185SAl Viro struct filename *name; 5229883d185SAl Viro struct nameidata *saved; 523fceef393SAl Viro struct inode *link_inode; 5249883d185SAl Viro unsigned root_seq; 5259883d185SAl Viro int dfd; 5263859a271SKees Cook } __randomize_layout; 5271f55a6ecSAl Viro 5289883d185SAl Viro static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) 529894bc8c4SAl Viro { 530756daf26SNeilBrown struct nameidata *old = current->nameidata; 531756daf26SNeilBrown p->stack = p->internal; 532c8a53ee5SAl Viro p->dfd = dfd; 533c8a53ee5SAl Viro p->name = name; 534756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 5359883d185SAl Viro p->saved = old; 536756daf26SNeilBrown current->nameidata = p; 537894bc8c4SAl Viro } 538894bc8c4SAl Viro 5399883d185SAl Viro static void restore_nameidata(void) 540894bc8c4SAl Viro { 5419883d185SAl Viro struct nameidata *now = current->nameidata, *old = now->saved; 542756daf26SNeilBrown 543756daf26SNeilBrown current->nameidata = old; 544756daf26SNeilBrown if (old) 545756daf26SNeilBrown old->total_link_count = now->total_link_count; 546e1a63bbcSAl Viro if (now->stack != now->internal) 547756daf26SNeilBrown kfree(now->stack); 548894bc8c4SAl Viro } 549894bc8c4SAl Viro 550894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 551894bc8c4SAl Viro { 552bc40aee0SAl Viro struct saved *p; 553bc40aee0SAl Viro 554bc40aee0SAl Viro if (nd->flags & LOOKUP_RCU) { 555bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 556bc40aee0SAl Viro GFP_ATOMIC); 557bc40aee0SAl Viro if (unlikely(!p)) 558bc40aee0SAl Viro return -ECHILD; 559bc40aee0SAl Viro } else { 560bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 561894bc8c4SAl Viro GFP_KERNEL); 562894bc8c4SAl Viro if (unlikely(!p)) 563894bc8c4SAl Viro return -ENOMEM; 564bc40aee0SAl Viro } 565894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 566894bc8c4SAl Viro nd->stack = p; 567894bc8c4SAl Viro return 0; 568894bc8c4SAl Viro } 569894bc8c4SAl Viro 570397d425dSEric W. Biederman /** 571397d425dSEric W. Biederman * path_connected - Verify that a path->dentry is below path->mnt.mnt_root 572397d425dSEric W. Biederman * @path: nameidate to verify 573397d425dSEric W. Biederman * 574397d425dSEric W. Biederman * Rename can sometimes move a file or directory outside of a bind 575397d425dSEric W. Biederman * mount, path_connected allows those cases to be detected. 576397d425dSEric W. Biederman */ 577397d425dSEric W. Biederman static bool path_connected(const struct path *path) 578397d425dSEric W. Biederman { 579397d425dSEric W. Biederman struct vfsmount *mnt = path->mnt; 580397d425dSEric W. Biederman 581397d425dSEric W. Biederman /* Only bind mounts can have disconnected paths */ 582397d425dSEric W. Biederman if (mnt->mnt_root == mnt->mnt_sb->s_root) 583397d425dSEric W. Biederman return true; 584397d425dSEric W. Biederman 585397d425dSEric W. Biederman return is_subdir(path->dentry, mnt->mnt_root); 586397d425dSEric W. Biederman } 587397d425dSEric W. Biederman 588894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 589894bc8c4SAl Viro { 590da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 591894bc8c4SAl Viro return 0; 592894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 593894bc8c4SAl Viro return 0; 594894bc8c4SAl Viro return __nd_alloc_stack(nd); 595894bc8c4SAl Viro } 596894bc8c4SAl Viro 5977973387aSAl Viro static void drop_links(struct nameidata *nd) 5987973387aSAl Viro { 5997973387aSAl Viro int i = nd->depth; 6007973387aSAl Viro while (i--) { 6017973387aSAl Viro struct saved *last = nd->stack + i; 602fceef393SAl Viro do_delayed_call(&last->done); 603fceef393SAl Viro clear_delayed_call(&last->done); 6047973387aSAl Viro } 6057973387aSAl Viro } 6067973387aSAl Viro 6077973387aSAl Viro static void terminate_walk(struct nameidata *nd) 6087973387aSAl Viro { 6097973387aSAl Viro drop_links(nd); 6107973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 6117973387aSAl Viro int i; 6127973387aSAl Viro path_put(&nd->path); 6137973387aSAl Viro for (i = 0; i < nd->depth; i++) 6147973387aSAl Viro path_put(&nd->stack[i].link); 615102b8af2SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 616102b8af2SAl Viro path_put(&nd->root); 617102b8af2SAl Viro nd->root.mnt = NULL; 618102b8af2SAl Viro } 6197973387aSAl Viro } else { 6207973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 6217973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6227973387aSAl Viro nd->root.mnt = NULL; 6237973387aSAl Viro rcu_read_unlock(); 6247973387aSAl Viro } 6257973387aSAl Viro nd->depth = 0; 6267973387aSAl Viro } 6277973387aSAl Viro 6287973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 6297973387aSAl Viro static bool legitimize_path(struct nameidata *nd, 6307973387aSAl Viro struct path *path, unsigned seq) 6317973387aSAl Viro { 6327973387aSAl Viro int res = __legitimize_mnt(path->mnt, nd->m_seq); 6337973387aSAl Viro if (unlikely(res)) { 6347973387aSAl Viro if (res > 0) 6357973387aSAl Viro path->mnt = NULL; 6367973387aSAl Viro path->dentry = NULL; 6377973387aSAl Viro return false; 6387973387aSAl Viro } 6397973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 6407973387aSAl Viro path->dentry = NULL; 6417973387aSAl Viro return false; 6427973387aSAl Viro } 6437973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6447973387aSAl Viro } 6457973387aSAl Viro 6467973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6477973387aSAl Viro { 6487973387aSAl Viro int i; 6497973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6507973387aSAl Viro struct saved *last = nd->stack + i; 6517973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6527973387aSAl Viro drop_links(nd); 6537973387aSAl Viro nd->depth = i + 1; 6547973387aSAl Viro return false; 6557973387aSAl Viro } 6567973387aSAl Viro } 6577973387aSAl Viro return true; 6587973387aSAl Viro } 6597973387aSAl Viro 66019660af7SAl Viro /* 66131e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 66219660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 66319660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 66457e3715cSMike Marshall * normal reference counts on dentries and vfsmounts to transition to ref-walk 66519660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 66619660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 66719660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 66819660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 66931e6b01fSNick Piggin */ 67031e6b01fSNick Piggin 67131e6b01fSNick Piggin /** 67219660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 67319660af7SAl Viro * @nd: nameidata pathwalk data 67439191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 67531e6b01fSNick Piggin * 6764675ac39SAl Viro * unlazy_walk attempts to legitimize the current nd->path and nd->root 6774675ac39SAl Viro * for ref-walk mode. 6784675ac39SAl Viro * Must be called from rcu-walk context. 6797973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6807973387aSAl Viro * terminate_walk(). 68131e6b01fSNick Piggin */ 6824675ac39SAl Viro static int unlazy_walk(struct nameidata *nd) 68331e6b01fSNick Piggin { 68431e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 68531e6b01fSNick Piggin 68631e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 687e5c832d5SLinus Torvalds 688e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6897973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6907973387aSAl Viro goto out2; 6914675ac39SAl Viro if (unlikely(!legitimize_path(nd, &nd->path, nd->seq))) 6924675ac39SAl Viro goto out1; 6934675ac39SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 6944675ac39SAl Viro if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq))) 6954675ac39SAl Viro goto out; 6964675ac39SAl Viro } 6974675ac39SAl Viro rcu_read_unlock(); 6984675ac39SAl Viro BUG_ON(nd->inode != parent->d_inode); 6994675ac39SAl Viro return 0; 7004675ac39SAl Viro 7014675ac39SAl Viro out2: 7024675ac39SAl Viro nd->path.mnt = NULL; 7034675ac39SAl Viro nd->path.dentry = NULL; 7044675ac39SAl Viro out1: 7054675ac39SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7064675ac39SAl Viro nd->root.mnt = NULL; 7074675ac39SAl Viro out: 7084675ac39SAl Viro rcu_read_unlock(); 7094675ac39SAl Viro return -ECHILD; 7104675ac39SAl Viro } 7114675ac39SAl Viro 7124675ac39SAl Viro /** 7134675ac39SAl Viro * unlazy_child - try to switch to ref-walk mode. 7144675ac39SAl Viro * @nd: nameidata pathwalk data 7154675ac39SAl Viro * @dentry: child of nd->path.dentry 7164675ac39SAl Viro * @seq: seq number to check dentry against 7174675ac39SAl Viro * Returns: 0 on success, -ECHILD on failure 7184675ac39SAl Viro * 7194675ac39SAl Viro * unlazy_child attempts to legitimize the current nd->path, nd->root and dentry 7204675ac39SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 7214675ac39SAl Viro * @nd. Must be called from rcu-walk context. 7224675ac39SAl Viro * Nothing should touch nameidata between unlazy_child() failure and 7234675ac39SAl Viro * terminate_walk(). 7244675ac39SAl Viro */ 7254675ac39SAl Viro static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned seq) 7264675ac39SAl Viro { 7274675ac39SAl Viro BUG_ON(!(nd->flags & LOOKUP_RCU)); 7284675ac39SAl Viro 7294675ac39SAl Viro nd->flags &= ~LOOKUP_RCU; 7304675ac39SAl Viro if (unlikely(!legitimize_links(nd))) 7314675ac39SAl Viro goto out2; 7327973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 7337973387aSAl Viro goto out2; 7344675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&nd->path.dentry->d_lockref))) 7357973387aSAl Viro goto out1; 73648a066e7SAl Viro 73715570086SLinus Torvalds /* 7384675ac39SAl Viro * We need to move both the parent and the dentry from the RCU domain 7394675ac39SAl Viro * to be properly refcounted. And the sequence number in the dentry 7404675ac39SAl Viro * validates *both* dentry counters, since we checked the sequence 7414675ac39SAl Viro * number of the parent after we got the child sequence number. So we 7424675ac39SAl Viro * know the parent must still be valid if the child sequence number is 74315570086SLinus Torvalds */ 7444675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) 745e5c832d5SLinus Torvalds goto out; 7464675ac39SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) { 7474675ac39SAl Viro rcu_read_unlock(); 7484675ac39SAl Viro dput(dentry); 7494675ac39SAl Viro goto drop_root_mnt; 75019660af7SAl Viro } 751e5c832d5SLinus Torvalds /* 752e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 753e5c832d5SLinus Torvalds * still valid and get it if required. 754e5c832d5SLinus Torvalds */ 755e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 7565a8d87e8SAl Viro if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq))) { 7575a8d87e8SAl Viro rcu_read_unlock(); 7585a8d87e8SAl Viro dput(dentry); 7595a8d87e8SAl Viro return -ECHILD; 7607973387aSAl Viro } 76131e6b01fSNick Piggin } 76231e6b01fSNick Piggin 7638b61e74fSAl Viro rcu_read_unlock(); 76431e6b01fSNick Piggin return 0; 76519660af7SAl Viro 7667973387aSAl Viro out2: 7677973387aSAl Viro nd->path.mnt = NULL; 7687973387aSAl Viro out1: 7697973387aSAl Viro nd->path.dentry = NULL; 770e5c832d5SLinus Torvalds out: 7718b61e74fSAl Viro rcu_read_unlock(); 772d0d27277SLinus Torvalds drop_root_mnt: 773d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 774d0d27277SLinus Torvalds nd->root.mnt = NULL; 77531e6b01fSNick Piggin return -ECHILD; 77631e6b01fSNick Piggin } 77731e6b01fSNick Piggin 7784ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 77934286d66SNick Piggin { 780a89f8337SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 7814ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 782a89f8337SAl Viro else 783a89f8337SAl Viro return 1; 78434286d66SNick Piggin } 78534286d66SNick Piggin 7869f1fafeeSAl Viro /** 7879f1fafeeSAl Viro * complete_walk - successful completion of path walk 7889f1fafeeSAl Viro * @nd: pointer nameidata 78939159de2SJeff Layton * 7909f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7919f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7929f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7939f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7949f1fafeeSAl Viro * need to drop nd->path. 79539159de2SJeff Layton */ 7969f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 79739159de2SJeff Layton { 79816c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 79939159de2SJeff Layton int status; 80039159de2SJeff Layton 8019f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 8029f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 8039f1fafeeSAl Viro nd->root.mnt = NULL; 8044675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 80548a066e7SAl Viro return -ECHILD; 80648a066e7SAl Viro } 8079f1fafeeSAl Viro 80816c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 80939159de2SJeff Layton return 0; 81039159de2SJeff Layton 811ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 81216c2cd71SAl Viro return 0; 81316c2cd71SAl Viro 814ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 81539159de2SJeff Layton if (status > 0) 81639159de2SJeff Layton return 0; 81739159de2SJeff Layton 81816c2cd71SAl Viro if (!status) 81939159de2SJeff Layton status = -ESTALE; 82016c2cd71SAl Viro 82139159de2SJeff Layton return status; 82239159de2SJeff Layton } 82339159de2SJeff Layton 82418d8c860SAl Viro static void set_root(struct nameidata *nd) 8252a737871SAl Viro { 82631e6b01fSNick Piggin struct fs_struct *fs = current->fs; 8279e6697e2SAl Viro 8289e6697e2SAl Viro if (nd->flags & LOOKUP_RCU) { 8298f47a016SAl Viro unsigned seq; 830c28cc364SNick Piggin 831c28cc364SNick Piggin do { 832c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 83331e6b01fSNick Piggin nd->root = fs->root; 8348f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 835c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 8369e6697e2SAl Viro } else { 8379e6697e2SAl Viro get_fs_root(fs, &nd->root); 8389e6697e2SAl Viro } 83931e6b01fSNick Piggin } 84031e6b01fSNick Piggin 8411d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 842051d3812SIan Kent { 843051d3812SIan Kent dput(path->dentry); 8444ac91378SJan Blunck if (path->mnt != nd->path.mnt) 845051d3812SIan Kent mntput(path->mnt); 846051d3812SIan Kent } 847051d3812SIan Kent 8487b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8497b9337aaSNick Piggin struct nameidata *nd) 850051d3812SIan Kent { 85131e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8524ac91378SJan Blunck dput(nd->path.dentry); 85331e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8544ac91378SJan Blunck mntput(nd->path.mnt); 8559a229683SHuang Shijie } 85631e6b01fSNick Piggin nd->path.mnt = path->mnt; 8574ac91378SJan Blunck nd->path.dentry = path->dentry; 858051d3812SIan Kent } 859051d3812SIan Kent 860248fb5b9SAl Viro static int nd_jump_root(struct nameidata *nd) 861248fb5b9SAl Viro { 862248fb5b9SAl Viro if (nd->flags & LOOKUP_RCU) { 863248fb5b9SAl Viro struct dentry *d; 864248fb5b9SAl Viro nd->path = nd->root; 865248fb5b9SAl Viro d = nd->path.dentry; 866248fb5b9SAl Viro nd->inode = d->d_inode; 867248fb5b9SAl Viro nd->seq = nd->root_seq; 868248fb5b9SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 869248fb5b9SAl Viro return -ECHILD; 870248fb5b9SAl Viro } else { 871248fb5b9SAl Viro path_put(&nd->path); 872248fb5b9SAl Viro nd->path = nd->root; 873248fb5b9SAl Viro path_get(&nd->path); 874248fb5b9SAl Viro nd->inode = nd->path.dentry->d_inode; 875248fb5b9SAl Viro } 876248fb5b9SAl Viro nd->flags |= LOOKUP_JUMPED; 877248fb5b9SAl Viro return 0; 878248fb5b9SAl Viro } 879248fb5b9SAl Viro 880b5fb63c1SChristoph Hellwig /* 8816b255391SAl Viro * Helper to directly jump to a known parsed path from ->get_link, 882b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 883b5fb63c1SChristoph Hellwig */ 8846e77137bSAl Viro void nd_jump_link(struct path *path) 885b5fb63c1SChristoph Hellwig { 8866e77137bSAl Viro struct nameidata *nd = current->nameidata; 887b5fb63c1SChristoph Hellwig path_put(&nd->path); 888b5fb63c1SChristoph Hellwig 889b5fb63c1SChristoph Hellwig nd->path = *path; 890b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 891b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 892b5fb63c1SChristoph Hellwig } 893b5fb63c1SChristoph Hellwig 894b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 895574197e0SAl Viro { 89621c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 897fceef393SAl Viro do_delayed_call(&last->done); 8986548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 899b9ff4429SAl Viro path_put(&last->link); 900574197e0SAl Viro } 901574197e0SAl Viro 902561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 903561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 904800179c9SKees Cook 905800179c9SKees Cook /** 906800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 90755852635SRandy Dunlap * @nd: nameidata pathwalk data 908800179c9SKees Cook * 909800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 910800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 911800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 912800179c9SKees Cook * processes from failing races against path names that may change out 913800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 914800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 915800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 916800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 917800179c9SKees Cook * 918800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 919800179c9SKees Cook */ 920fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 921800179c9SKees Cook { 922800179c9SKees Cook const struct inode *inode; 923800179c9SKees Cook const struct inode *parent; 9242d7f9e2aSSeth Forshee kuid_t puid; 925800179c9SKees Cook 926800179c9SKees Cook if (!sysctl_protected_symlinks) 927800179c9SKees Cook return 0; 928800179c9SKees Cook 929800179c9SKees Cook /* Allowed if owner and follower match. */ 930fceef393SAl Viro inode = nd->link_inode; 93181abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 932800179c9SKees Cook return 0; 933800179c9SKees Cook 934800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 935aa65fa35SAl Viro parent = nd->inode; 936800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 937800179c9SKees Cook return 0; 938800179c9SKees Cook 939800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 9402d7f9e2aSSeth Forshee puid = parent->i_uid; 9412d7f9e2aSSeth Forshee if (uid_valid(puid) && uid_eq(puid, inode->i_uid)) 942800179c9SKees Cook return 0; 943800179c9SKees Cook 94431956502SAl Viro if (nd->flags & LOOKUP_RCU) 94531956502SAl Viro return -ECHILD; 94631956502SAl Viro 9471cf2665bSAl Viro audit_log_link_denied("follow_link", &nd->stack[0].link); 948800179c9SKees Cook return -EACCES; 949800179c9SKees Cook } 950800179c9SKees Cook 951800179c9SKees Cook /** 952800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 953800179c9SKees Cook * @inode: the source inode to hardlink from 954800179c9SKees Cook * 955800179c9SKees Cook * Return false if at least one of the following conditions: 956800179c9SKees Cook * - inode is not a regular file 957800179c9SKees Cook * - inode is setuid 958800179c9SKees Cook * - inode is setgid and group-exec 959800179c9SKees Cook * - access failure for read and write 960800179c9SKees Cook * 961800179c9SKees Cook * Otherwise returns true. 962800179c9SKees Cook */ 963800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 964800179c9SKees Cook { 965800179c9SKees Cook umode_t mode = inode->i_mode; 966800179c9SKees Cook 967800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 968800179c9SKees Cook if (!S_ISREG(mode)) 969800179c9SKees Cook return false; 970800179c9SKees Cook 971800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 972800179c9SKees Cook if (mode & S_ISUID) 973800179c9SKees Cook return false; 974800179c9SKees Cook 975800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 976800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 977800179c9SKees Cook return false; 978800179c9SKees Cook 979800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 980800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 981800179c9SKees Cook return false; 982800179c9SKees Cook 983800179c9SKees Cook return true; 984800179c9SKees Cook } 985800179c9SKees Cook 986800179c9SKees Cook /** 987800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 988800179c9SKees Cook * @link: the source to hardlink from 989800179c9SKees Cook * 990800179c9SKees Cook * Block hardlink when all of: 991800179c9SKees Cook * - sysctl_protected_hardlinks enabled 992800179c9SKees Cook * - fsuid does not match inode 993800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 994f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 995800179c9SKees Cook * 996800179c9SKees Cook * Returns 0 if successful, -ve on error. 997800179c9SKees Cook */ 998800179c9SKees Cook static int may_linkat(struct path *link) 999800179c9SKees Cook { 1000800179c9SKees Cook struct inode *inode; 1001800179c9SKees Cook 1002800179c9SKees Cook if (!sysctl_protected_hardlinks) 1003800179c9SKees Cook return 0; 1004800179c9SKees Cook 1005800179c9SKees Cook inode = link->dentry->d_inode; 1006800179c9SKees Cook 1007800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 1008800179c9SKees Cook * otherwise, it must be a safe source. 1009800179c9SKees Cook */ 1010cc658db4SKees Cook if (safe_hardlink_source(inode) || inode_owner_or_capable(inode)) 1011800179c9SKees Cook return 0; 1012800179c9SKees Cook 1013a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 1014800179c9SKees Cook return -EPERM; 1015800179c9SKees Cook } 1016800179c9SKees Cook 10173b2e7f75SAl Viro static __always_inline 10183b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 10191da177e4SLinus Torvalds { 1020ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 10211cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 1022fceef393SAl Viro struct inode *inode = nd->link_inode; 10236d7b5aaeSAl Viro int error; 10240a959df5SAl Viro const char *res; 10251da177e4SLinus Torvalds 10268fa9dd24SNeilBrown if (!(nd->flags & LOOKUP_RCU)) { 10278fa9dd24SNeilBrown touch_atime(&last->link); 10288fa9dd24SNeilBrown cond_resched(); 1029598e3c8fSMiklos Szeredi } else if (atime_needs_update_rcu(&last->link, inode)) { 10304675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 10318fa9dd24SNeilBrown return ERR_PTR(-ECHILD); 10328fa9dd24SNeilBrown touch_atime(&last->link); 10338fa9dd24SNeilBrown } 10348fa9dd24SNeilBrown 1035bda0be7aSNeilBrown error = security_inode_follow_link(dentry, inode, 1036bda0be7aSNeilBrown nd->flags & LOOKUP_RCU); 1037bda0be7aSNeilBrown if (unlikely(error)) 10386920a440SAl Viro return ERR_PTR(error); 103936f3b4f6SAl Viro 104086acdca1SAl Viro nd->last_type = LAST_BIND; 1041d4dee48bSAl Viro res = inode->i_link; 1042d4dee48bSAl Viro if (!res) { 1043fceef393SAl Viro const char * (*get)(struct dentry *, struct inode *, 1044fceef393SAl Viro struct delayed_call *); 1045fceef393SAl Viro get = inode->i_op->get_link; 10468c1b4566SAl Viro if (nd->flags & LOOKUP_RCU) { 1047fceef393SAl Viro res = get(NULL, inode, &last->done); 10486b255391SAl Viro if (res == ERR_PTR(-ECHILD)) { 10494675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 10508c1b4566SAl Viro return ERR_PTR(-ECHILD); 1051fceef393SAl Viro res = get(dentry, inode, &last->done); 10528c1b4566SAl Viro } 10536b255391SAl Viro } else { 1054fceef393SAl Viro res = get(dentry, inode, &last->done); 10556b255391SAl Viro } 1056fceef393SAl Viro if (IS_ERR_OR_NULL(res)) 1057fab51e8aSAl Viro return res; 10580a959df5SAl Viro } 1059fab51e8aSAl Viro if (*res == '/') { 1060fab51e8aSAl Viro if (!nd->root.mnt) 1061fab51e8aSAl Viro set_root(nd); 1062248fb5b9SAl Viro if (unlikely(nd_jump_root(nd))) 1063fab51e8aSAl Viro return ERR_PTR(-ECHILD); 1064fab51e8aSAl Viro while (unlikely(*++res == '/')) 1065fab51e8aSAl Viro ; 1066fab51e8aSAl Viro } 1067fab51e8aSAl Viro if (!*res) 1068fab51e8aSAl Viro res = NULL; 10690a959df5SAl Viro return res; 10700a959df5SAl Viro } 10716d7b5aaeSAl Viro 1072f015f126SDavid Howells /* 1073f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1074f015f126SDavid Howells * 1075f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1076f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1077f015f126SDavid Howells * Up is towards /. 1078f015f126SDavid Howells * 1079f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1080f015f126SDavid Howells * root. 1081f015f126SDavid Howells */ 1082bab77ebfSAl Viro int follow_up(struct path *path) 10831da177e4SLinus Torvalds { 10840714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 10850714a533SAl Viro struct mount *parent; 10861da177e4SLinus Torvalds struct dentry *mountpoint; 108799b7db7bSNick Piggin 108848a066e7SAl Viro read_seqlock_excl(&mount_lock); 10890714a533SAl Viro parent = mnt->mnt_parent; 10903c0a6163SAl Viro if (parent == mnt) { 109148a066e7SAl Viro read_sequnlock_excl(&mount_lock); 10921da177e4SLinus Torvalds return 0; 10931da177e4SLinus Torvalds } 10940714a533SAl Viro mntget(&parent->mnt); 1095a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 109648a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1097bab77ebfSAl Viro dput(path->dentry); 1098bab77ebfSAl Viro path->dentry = mountpoint; 1099bab77ebfSAl Viro mntput(path->mnt); 11000714a533SAl Viro path->mnt = &parent->mnt; 11011da177e4SLinus Torvalds return 1; 11021da177e4SLinus Torvalds } 11034d359507SAl Viro EXPORT_SYMBOL(follow_up); 11041da177e4SLinus Torvalds 1105b5c84bf6SNick Piggin /* 11069875cf80SDavid Howells * Perform an automount 11079875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 11089875cf80SDavid Howells * were called with. 11091da177e4SLinus Torvalds */ 1110756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 11119875cf80SDavid Howells bool *need_mntput) 111231e6b01fSNick Piggin { 11139875cf80SDavid Howells struct vfsmount *mnt; 1114ea5b778aSDavid Howells int err; 11159875cf80SDavid Howells 11169875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 11179875cf80SDavid Howells return -EREMOTE; 11189875cf80SDavid Howells 11190ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 11200ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 11210ec26fd0SMiklos Szeredi * the name. 11220ec26fd0SMiklos Szeredi * 11230ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 11245a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 11250ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 11260ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 11270ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 11280ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 11295a30d8a2SDavid Howells */ 1130756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 113142f46148SIan Kent LOOKUP_OPEN | LOOKUP_CREATE | 113242f46148SIan Kent LOOKUP_AUTOMOUNT))) { 113342f46148SIan Kent /* Positive dentry that isn't meant to trigger an 113442f46148SIan Kent * automount, EISDIR will allow it to be used, 113542f46148SIan Kent * otherwise there's no mount here "now" so return 113642f46148SIan Kent * ENOENT. 113742f46148SIan Kent */ 113842f46148SIan Kent if (path->dentry->d_inode) 11399875cf80SDavid Howells return -EISDIR; 114042f46148SIan Kent else 114142f46148SIan Kent return -ENOENT; 114242f46148SIan Kent } 11430ec26fd0SMiklos Szeredi 1144aeaa4a79SEric W. Biederman if (path->dentry->d_sb->s_user_ns != &init_user_ns) 1145aeaa4a79SEric W. Biederman return -EACCES; 1146aeaa4a79SEric W. Biederman 1147756daf26SNeilBrown nd->total_link_count++; 1148756daf26SNeilBrown if (nd->total_link_count >= 40) 11499875cf80SDavid Howells return -ELOOP; 11509875cf80SDavid Howells 11519875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 11529875cf80SDavid Howells if (IS_ERR(mnt)) { 11539875cf80SDavid Howells /* 11549875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 11559875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 11569875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 11579875cf80SDavid Howells * 11589875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 11599875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 11609875cf80SDavid Howells * the path is inaccessible and we should say so. 11619875cf80SDavid Howells */ 1162756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 11639875cf80SDavid Howells return -EREMOTE; 11649875cf80SDavid Howells return PTR_ERR(mnt); 116531e6b01fSNick Piggin } 1166ea5b778aSDavid Howells 11679875cf80SDavid Howells if (!mnt) /* mount collision */ 11689875cf80SDavid Howells return 0; 11699875cf80SDavid Howells 11708aef1884SAl Viro if (!*need_mntput) { 11718aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 11728aef1884SAl Viro mntget(path->mnt); 11738aef1884SAl Viro *need_mntput = true; 11748aef1884SAl Viro } 117519a167afSAl Viro err = finish_automount(mnt, path); 1176ea5b778aSDavid Howells 1177ea5b778aSDavid Howells switch (err) { 1178ea5b778aSDavid Howells case -EBUSY: 1179ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 118019a167afSAl Viro return 0; 1181ea5b778aSDavid Howells case 0: 11828aef1884SAl Viro path_put(path); 11839875cf80SDavid Howells path->mnt = mnt; 11849875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 11859875cf80SDavid Howells return 0; 118619a167afSAl Viro default: 118719a167afSAl Viro return err; 11889875cf80SDavid Howells } 118919a167afSAl Viro 1190ea5b778aSDavid Howells } 11919875cf80SDavid Howells 11929875cf80SDavid Howells /* 11939875cf80SDavid Howells * Handle a dentry that is managed in some way. 1194cc53ce53SDavid Howells * - Flagged for transit management (autofs) 11959875cf80SDavid Howells * - Flagged as mountpoint 11969875cf80SDavid Howells * - Flagged as automount point 11979875cf80SDavid Howells * 11989875cf80SDavid Howells * This may only be called in refwalk mode. 11999875cf80SDavid Howells * 12009875cf80SDavid Howells * Serialization is taken care of in namespace.c 12019875cf80SDavid Howells */ 1202756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 12039875cf80SDavid Howells { 12048aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 12059875cf80SDavid Howells unsigned managed; 12069875cf80SDavid Howells bool need_mntput = false; 12078aef1884SAl Viro int ret = 0; 12089875cf80SDavid Howells 12099875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 12109875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 12119875cf80SDavid Howells * the components of that value change under us */ 12129875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 12139875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 12149875cf80SDavid Howells unlikely(managed != 0)) { 1215cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1216cc53ce53SDavid Howells * being held. */ 1217cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1218cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1219cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1220fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1221cc53ce53SDavid Howells if (ret < 0) 12228aef1884SAl Viro break; 1223cc53ce53SDavid Howells } 1224cc53ce53SDavid Howells 12259875cf80SDavid Howells /* Transit to a mounted filesystem. */ 12269875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 12279875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12289875cf80SDavid Howells if (mounted) { 12299875cf80SDavid Howells dput(path->dentry); 12309875cf80SDavid Howells if (need_mntput) 1231463ffb2eSAl Viro mntput(path->mnt); 1232463ffb2eSAl Viro path->mnt = mounted; 1233463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 12349875cf80SDavid Howells need_mntput = true; 12359875cf80SDavid Howells continue; 1236463ffb2eSAl Viro } 1237463ffb2eSAl Viro 12389875cf80SDavid Howells /* Something is mounted on this dentry in another 12399875cf80SDavid Howells * namespace and/or whatever was mounted there in this 124048a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 124148a066e7SAl Viro * get it */ 12421da177e4SLinus Torvalds } 12439875cf80SDavid Howells 12449875cf80SDavid Howells /* Handle an automount point */ 12459875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1246756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 12479875cf80SDavid Howells if (ret < 0) 12488aef1884SAl Viro break; 12499875cf80SDavid Howells continue; 12509875cf80SDavid Howells } 12519875cf80SDavid Howells 12529875cf80SDavid Howells /* We didn't change the current path point */ 12539875cf80SDavid Howells break; 12549875cf80SDavid Howells } 12558aef1884SAl Viro 12568aef1884SAl Viro if (need_mntput && path->mnt == mnt) 12578aef1884SAl Viro mntput(path->mnt); 1258e9742b53SAl Viro if (ret == -EISDIR || !ret) 1259e9742b53SAl Viro ret = 1; 12608402752eSAl Viro if (need_mntput) 12618402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 12628402752eSAl Viro if (unlikely(ret < 0)) 12638402752eSAl Viro path_put_conditional(path, nd); 12648402752eSAl Viro return ret; 12651da177e4SLinus Torvalds } 12661da177e4SLinus Torvalds 1267cc53ce53SDavid Howells int follow_down_one(struct path *path) 12681da177e4SLinus Torvalds { 12691da177e4SLinus Torvalds struct vfsmount *mounted; 12701da177e4SLinus Torvalds 12711c755af4SAl Viro mounted = lookup_mnt(path); 12721da177e4SLinus Torvalds if (mounted) { 12739393bd07SAl Viro dput(path->dentry); 12749393bd07SAl Viro mntput(path->mnt); 12759393bd07SAl Viro path->mnt = mounted; 12769393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12771da177e4SLinus Torvalds return 1; 12781da177e4SLinus Torvalds } 12791da177e4SLinus Torvalds return 0; 12801da177e4SLinus Torvalds } 12814d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12821da177e4SLinus Torvalds 1283fb5f51c7SIan Kent static inline int managed_dentry_rcu(const struct path *path) 128462a7375eSIan Kent { 1285fb5f51c7SIan Kent return (path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1286fb5f51c7SIan Kent path->dentry->d_op->d_manage(path, true) : 0; 128762a7375eSIan Kent } 128862a7375eSIan Kent 12899875cf80SDavid Howells /* 1290287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1291287548e4SAl Viro * we meet a managed dentry that would need blocking. 12929875cf80SDavid Howells */ 12939875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1294254cf582SAl Viro struct inode **inode, unsigned *seqp) 12959875cf80SDavid Howells { 129662a7375eSIan Kent for (;;) { 1297c7105365SAl Viro struct mount *mounted; 129862a7375eSIan Kent /* 129962a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 130062a7375eSIan Kent * that wants to block transit. 130162a7375eSIan Kent */ 1302fb5f51c7SIan Kent switch (managed_dentry_rcu(path)) { 1303b8faf035SNeilBrown case -ECHILD: 1304b8faf035SNeilBrown default: 1305ab90911fSDavid Howells return false; 1306b8faf035SNeilBrown case -EISDIR: 1307b8faf035SNeilBrown return true; 1308b8faf035SNeilBrown case 0: 1309b8faf035SNeilBrown break; 1310b8faf035SNeilBrown } 131162a7375eSIan Kent 131262a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1313b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 131462a7375eSIan Kent 1315474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 13169875cf80SDavid Howells if (!mounted) 13179875cf80SDavid Howells break; 1318c7105365SAl Viro path->mnt = &mounted->mnt; 1319c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1320a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1321254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 132259430262SLinus Torvalds /* 132359430262SLinus Torvalds * Update the inode too. We don't need to re-check the 132459430262SLinus Torvalds * dentry sequence number here after this d_inode read, 132559430262SLinus Torvalds * because a mount-point is always pinned. 132659430262SLinus Torvalds */ 132759430262SLinus Torvalds *inode = path->dentry->d_inode; 13289875cf80SDavid Howells } 1329f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1330b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1331287548e4SAl Viro } 1332287548e4SAl Viro 133331e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 133431e6b01fSNick Piggin { 13354023bfc9SAl Viro struct inode *inode = nd->inode; 133631e6b01fSNick Piggin 133731e6b01fSNick Piggin while (1) { 1338aed434adSAl Viro if (path_equal(&nd->path, &nd->root)) 133931e6b01fSNick Piggin break; 134031e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 134131e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 134231e6b01fSNick Piggin struct dentry *parent = old->d_parent; 134331e6b01fSNick Piggin unsigned seq; 134431e6b01fSNick Piggin 13454023bfc9SAl Viro inode = parent->d_inode; 134631e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 1347aed434adSAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 1348aed434adSAl Viro return -ECHILD; 134931e6b01fSNick Piggin nd->path.dentry = parent; 135031e6b01fSNick Piggin nd->seq = seq; 1351397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 1352397d425dSEric W. Biederman return -ENOENT; 135331e6b01fSNick Piggin break; 1354aed434adSAl Viro } else { 1355aed434adSAl Viro struct mount *mnt = real_mount(nd->path.mnt); 1356aed434adSAl Viro struct mount *mparent = mnt->mnt_parent; 1357aed434adSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1358aed434adSAl Viro struct inode *inode2 = mountpoint->d_inode; 1359aed434adSAl Viro unsigned seq = read_seqcount_begin(&mountpoint->d_seq); 1360aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1361aed434adSAl Viro return -ECHILD; 1362aed434adSAl Viro if (&mparent->mnt == nd->path.mnt) 136331e6b01fSNick Piggin break; 1364aed434adSAl Viro /* we know that mountpoint was pinned */ 1365aed434adSAl Viro nd->path.dentry = mountpoint; 1366aed434adSAl Viro nd->path.mnt = &mparent->mnt; 1367aed434adSAl Viro inode = inode2; 1368aed434adSAl Viro nd->seq = seq; 136931e6b01fSNick Piggin } 1370aed434adSAl Viro } 1371aed434adSAl Viro while (unlikely(d_mountpoint(nd->path.dentry))) { 1372b37199e6SAl Viro struct mount *mounted; 1373b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1374aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1375aed434adSAl Viro return -ECHILD; 1376b37199e6SAl Viro if (!mounted) 1377b37199e6SAl Viro break; 1378b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1379b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 13804023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1381b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1382b37199e6SAl Viro } 13834023bfc9SAl Viro nd->inode = inode; 138431e6b01fSNick Piggin return 0; 138531e6b01fSNick Piggin } 138631e6b01fSNick Piggin 13879875cf80SDavid Howells /* 1388cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1389cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1390cc53ce53SDavid Howells * caller is permitted to proceed or not. 1391cc53ce53SDavid Howells */ 13927cc90cc3SAl Viro int follow_down(struct path *path) 1393cc53ce53SDavid Howells { 1394cc53ce53SDavid Howells unsigned managed; 1395cc53ce53SDavid Howells int ret; 1396cc53ce53SDavid Howells 1397cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1398cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1399cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1400cc53ce53SDavid Howells * being held. 1401cc53ce53SDavid Howells * 1402cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1403cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1404cc53ce53SDavid Howells * other than its daemon the right to mount on its 1405cc53ce53SDavid Howells * superstructure. 1406cc53ce53SDavid Howells * 1407cc53ce53SDavid Howells * The filesystem may sleep at this point. 1408cc53ce53SDavid Howells */ 1409cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1410cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1411cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1412fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1413cc53ce53SDavid Howells if (ret < 0) 1414cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1415cc53ce53SDavid Howells } 1416cc53ce53SDavid Howells 1417cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1418cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1419cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1420cc53ce53SDavid Howells if (!mounted) 1421cc53ce53SDavid Howells break; 1422cc53ce53SDavid Howells dput(path->dentry); 1423cc53ce53SDavid Howells mntput(path->mnt); 1424cc53ce53SDavid Howells path->mnt = mounted; 1425cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1426cc53ce53SDavid Howells continue; 1427cc53ce53SDavid Howells } 1428cc53ce53SDavid Howells 1429cc53ce53SDavid Howells /* Don't handle automount points here */ 1430cc53ce53SDavid Howells break; 1431cc53ce53SDavid Howells } 1432cc53ce53SDavid Howells return 0; 1433cc53ce53SDavid Howells } 14344d359507SAl Viro EXPORT_SYMBOL(follow_down); 1435cc53ce53SDavid Howells 1436cc53ce53SDavid Howells /* 14379875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 14389875cf80SDavid Howells */ 14399875cf80SDavid Howells static void follow_mount(struct path *path) 14409875cf80SDavid Howells { 14419875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 14429875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 14439875cf80SDavid Howells if (!mounted) 14449875cf80SDavid Howells break; 14459875cf80SDavid Howells dput(path->dentry); 14469875cf80SDavid Howells mntput(path->mnt); 14479875cf80SDavid Howells path->mnt = mounted; 14489875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 14499875cf80SDavid Howells } 14509875cf80SDavid Howells } 14519875cf80SDavid Howells 1452eedf265aSEric W. Biederman static int path_parent_directory(struct path *path) 1453eedf265aSEric W. Biederman { 1454eedf265aSEric W. Biederman struct dentry *old = path->dentry; 1455eedf265aSEric W. Biederman /* rare case of legitimate dget_parent()... */ 1456eedf265aSEric W. Biederman path->dentry = dget_parent(path->dentry); 1457eedf265aSEric W. Biederman dput(old); 1458eedf265aSEric W. Biederman if (unlikely(!path_connected(path))) 1459eedf265aSEric W. Biederman return -ENOENT; 1460eedf265aSEric W. Biederman return 0; 1461eedf265aSEric W. Biederman } 1462eedf265aSEric W. Biederman 1463397d425dSEric W. Biederman static int follow_dotdot(struct nameidata *nd) 14641da177e4SLinus Torvalds { 14651da177e4SLinus Torvalds while(1) { 14662a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 14672a737871SAl Viro nd->path.mnt == nd->root.mnt) { 14681da177e4SLinus Torvalds break; 14691da177e4SLinus Torvalds } 14704ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 1471eedf265aSEric W. Biederman int ret = path_parent_directory(&nd->path); 1472eedf265aSEric W. Biederman if (ret) 1473eedf265aSEric W. Biederman return ret; 14741da177e4SLinus Torvalds break; 14751da177e4SLinus Torvalds } 14763088dd70SAl Viro if (!follow_up(&nd->path)) 14771da177e4SLinus Torvalds break; 14781da177e4SLinus Torvalds } 147979ed0226SAl Viro follow_mount(&nd->path); 148031e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 1481397d425dSEric W. Biederman return 0; 14821da177e4SLinus Torvalds } 14831da177e4SLinus Torvalds 14841da177e4SLinus Torvalds /* 1485f4fdace9SOleg Drokin * This looks up the name in dcache and possibly revalidates the found dentry. 1486f4fdace9SOleg Drokin * NULL is returned if the dentry does not exist in the cache. 1487baa03890SNick Piggin */ 1488e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1489e3c13928SAl Viro struct dentry *dir, 14906c51e513SAl Viro unsigned int flags) 1491baa03890SNick Piggin { 1492a89f8337SAl Viro struct dentry *dentry = d_lookup(dir, name); 1493bad61189SMiklos Szeredi if (dentry) { 1494a89f8337SAl Viro int error = d_revalidate(dentry, flags); 1495bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 149674ff0ffcSAl Viro if (!error) 14975542aa2fSEric W. Biederman d_invalidate(dentry); 1498bad61189SMiklos Szeredi dput(dentry); 149974ff0ffcSAl Viro return ERR_PTR(error); 1500bad61189SMiklos Szeredi } 1501bad61189SMiklos Szeredi } 1502baa03890SNick Piggin return dentry; 1503baa03890SNick Piggin } 1504baa03890SNick Piggin 1505baa03890SNick Piggin /* 150613a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 150713a2c3beSJ. Bruce Fields * unhashed. 1508bad61189SMiklos Szeredi * 1509bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 151044396f4bSJosef Bacik */ 1511bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 151272bd866aSAl Viro unsigned int flags) 151344396f4bSJosef Bacik { 151444396f4bSJosef Bacik struct dentry *old; 151544396f4bSJosef Bacik 151644396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1517bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1518e188dc02SMiklos Szeredi dput(dentry); 151944396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1520e188dc02SMiklos Szeredi } 152144396f4bSJosef Bacik 152272bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 152344396f4bSJosef Bacik if (unlikely(old)) { 152444396f4bSJosef Bacik dput(dentry); 152544396f4bSJosef Bacik dentry = old; 152644396f4bSJosef Bacik } 152744396f4bSJosef Bacik return dentry; 152844396f4bSJosef Bacik } 152944396f4bSJosef Bacik 1530e3c13928SAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 153172bd866aSAl Viro struct dentry *base, unsigned int flags) 1532a3255546SAl Viro { 15336c51e513SAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 1534a3255546SAl Viro 15356c51e513SAl Viro if (dentry) 1536a3255546SAl Viro return dentry; 1537bad61189SMiklos Szeredi 15386c51e513SAl Viro dentry = d_alloc(base, name); 15396c51e513SAl Viro if (unlikely(!dentry)) 15406c51e513SAl Viro return ERR_PTR(-ENOMEM); 15416c51e513SAl Viro 154272bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1543a3255546SAl Viro } 1544a3255546SAl Viro 1545e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 1546254cf582SAl Viro struct path *path, struct inode **inode, 1547254cf582SAl Viro unsigned *seqp) 15481da177e4SLinus Torvalds { 15494ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 155031e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 15515a18fff2SAl Viro int status = 1; 15529875cf80SDavid Howells int err; 15539875cf80SDavid Howells 15543cac260aSAl Viro /* 1555b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 15565d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 15575d0f49c1SAl Viro * going to fall back to non-racy lookup. 1558b04f784eSNick Piggin */ 155931e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 156031e6b01fSNick Piggin unsigned seq; 1561766c4cbfSAl Viro bool negative; 1562da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15635d0f49c1SAl Viro if (unlikely(!dentry)) { 15644675ac39SAl Viro if (unlazy_walk(nd)) 15655d0f49c1SAl Viro return -ECHILD; 1566e9742b53SAl Viro return 0; 15675d0f49c1SAl Viro } 15685a18fff2SAl Viro 156912f8ad4bSLinus Torvalds /* 157012f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 157112f8ad4bSLinus Torvalds * the dentry name information from lookup. 157212f8ad4bSLinus Torvalds */ 157363afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1574766c4cbfSAl Viro negative = d_is_negative(dentry); 15755d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 157612f8ad4bSLinus Torvalds return -ECHILD; 157712f8ad4bSLinus Torvalds 157812f8ad4bSLinus Torvalds /* 157912f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 158012f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 158112f8ad4bSLinus Torvalds * 158212f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 158312f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 158412f8ad4bSLinus Torvalds */ 15855d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 158631e6b01fSNick Piggin return -ECHILD; 15875a18fff2SAl Viro 1588254cf582SAl Viro *seqp = seq; 15894ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 1590209a7fb2SAl Viro if (likely(status > 0)) { 1591daf3761cSTrond Myklebust /* 1592daf3761cSTrond Myklebust * Note: do negative dentry check after revalidation in 1593daf3761cSTrond Myklebust * case that drops it. 1594daf3761cSTrond Myklebust */ 15955d0f49c1SAl Viro if (unlikely(negative)) 1596daf3761cSTrond Myklebust return -ENOENT; 159731e6b01fSNick Piggin path->mnt = mnt; 159831e6b01fSNick Piggin path->dentry = dentry; 1599254cf582SAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 1600e9742b53SAl Viro return 1; 16015d0f49c1SAl Viro } 16024675ac39SAl Viro if (unlazy_child(nd, dentry, seq)) 1603254cf582SAl Viro return -ECHILD; 1604209a7fb2SAl Viro if (unlikely(status == -ECHILD)) 1605209a7fb2SAl Viro /* we'd been told to redo it in non-rcu mode */ 1606209a7fb2SAl Viro status = d_revalidate(dentry, nd->flags); 16075a18fff2SAl Viro } else { 1608e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 160981e6f520SAl Viro if (unlikely(!dentry)) 1610e9742b53SAl Viro return 0; 16114ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 16125d0f49c1SAl Viro } 16135a18fff2SAl Viro if (unlikely(status <= 0)) { 1614e9742b53SAl Viro if (!status) 16155d0f49c1SAl Viro d_invalidate(dentry); 16165a18fff2SAl Viro dput(dentry); 16175a18fff2SAl Viro return status; 16185a18fff2SAl Viro } 1619766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1620766c4cbfSAl Viro dput(dentry); 1621766c4cbfSAl Viro return -ENOENT; 1622766c4cbfSAl Viro } 16235d0f49c1SAl Viro 16241da177e4SLinus Torvalds path->mnt = mnt; 16251da177e4SLinus Torvalds path->dentry = dentry; 1626756daf26SNeilBrown err = follow_managed(path, nd); 1627e9742b53SAl Viro if (likely(err > 0)) 162863afdfc7SDavid Howells *inode = d_backing_inode(path->dentry); 16298402752eSAl Viro return err; 1630697f514dSMiklos Szeredi } 1631697f514dSMiklos Szeredi 1632697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1633e3c13928SAl Viro static struct dentry *lookup_slow(const struct qstr *name, 1634e3c13928SAl Viro struct dentry *dir, 1635e3c13928SAl Viro unsigned int flags) 1636697f514dSMiklos Szeredi { 163794bdd655SAl Viro struct dentry *dentry = ERR_PTR(-ENOENT), *old; 16381936386eSAl Viro struct inode *inode = dir->d_inode; 1639d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 16401936386eSAl Viro 16419902af79SAl Viro inode_lock_shared(inode); 16421936386eSAl Viro /* Don't go there if it's already dead */ 164394bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 164494bdd655SAl Viro goto out; 164594bdd655SAl Viro again: 1646d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 164794bdd655SAl Viro if (IS_ERR(dentry)) 164894bdd655SAl Viro goto out; 164994bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1650a89f8337SAl Viro if (!(flags & LOOKUP_NO_REVAL)) { 1651949a852eSAl Viro int error = d_revalidate(dentry, flags); 1652949a852eSAl Viro if (unlikely(error <= 0)) { 165394bdd655SAl Viro if (!error) { 1654949a852eSAl Viro d_invalidate(dentry); 1655949a852eSAl Viro dput(dentry); 165694bdd655SAl Viro goto again; 165794bdd655SAl Viro } 165894bdd655SAl Viro dput(dentry); 1659949a852eSAl Viro dentry = ERR_PTR(error); 1660949a852eSAl Viro } 1661949a852eSAl Viro } 166294bdd655SAl Viro } else { 16631936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 166485c7f810SAl Viro d_lookup_done(dentry); 16651936386eSAl Viro if (unlikely(old)) { 16661936386eSAl Viro dput(dentry); 16671936386eSAl Viro dentry = old; 1668949a852eSAl Viro } 1669949a852eSAl Viro } 167094bdd655SAl Viro out: 16719902af79SAl Viro inode_unlock_shared(inode); 1672e3c13928SAl Viro return dentry; 16731da177e4SLinus Torvalds } 16741da177e4SLinus Torvalds 167552094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 167652094c8aSAl Viro { 167752094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16784ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 167952094c8aSAl Viro if (err != -ECHILD) 168052094c8aSAl Viro return err; 16814675ac39SAl Viro if (unlazy_walk(nd)) 168252094c8aSAl Viro return -ECHILD; 168352094c8aSAl Viro } 16844ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 168552094c8aSAl Viro } 168652094c8aSAl Viro 16879856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 16889856fa1bSAl Viro { 16899856fa1bSAl Viro if (type == LAST_DOTDOT) { 16909e6697e2SAl Viro if (!nd->root.mnt) 16919e6697e2SAl Viro set_root(nd); 16929856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 169370291aecSAl Viro return follow_dotdot_rcu(nd); 16949856fa1bSAl Viro } else 1695397d425dSEric W. Biederman return follow_dotdot(nd); 16969856fa1bSAl Viro } 16979856fa1bSAl Viro return 0; 16989856fa1bSAl Viro } 16999856fa1bSAl Viro 1700181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1701181548c0SAl Viro struct inode *inode, unsigned seq) 1702d63ff28fSAl Viro { 1703626de996SAl Viro int error; 17041cf2665bSAl Viro struct saved *last; 1705756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1706626de996SAl Viro path_to_nameidata(link, nd); 1707626de996SAl Viro return -ELOOP; 1708626de996SAl Viro } 1709bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1710cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1711cd179f44SAl Viro mntget(link->mnt); 17127973387aSAl Viro } 1713626de996SAl Viro error = nd_alloc_stack(nd); 1714626de996SAl Viro if (unlikely(error)) { 1715bc40aee0SAl Viro if (error == -ECHILD) { 1716ad1633a1SAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 1717ad1633a1SAl Viro drop_links(nd); 1718ad1633a1SAl Viro nd->depth = 0; 1719ad1633a1SAl Viro nd->flags &= ~LOOKUP_RCU; 1720ad1633a1SAl Viro nd->path.mnt = NULL; 1721ad1633a1SAl Viro nd->path.dentry = NULL; 1722ad1633a1SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1723ad1633a1SAl Viro nd->root.mnt = NULL; 1724ad1633a1SAl Viro rcu_read_unlock(); 17254675ac39SAl Viro } else if (likely(unlazy_walk(nd)) == 0) 1726bc40aee0SAl Viro error = nd_alloc_stack(nd); 1727bc40aee0SAl Viro } 1728bc40aee0SAl Viro if (error) { 1729cd179f44SAl Viro path_put(link); 1730626de996SAl Viro return error; 1731626de996SAl Viro } 1732bc40aee0SAl Viro } 1733626de996SAl Viro 1734ab104923SAl Viro last = nd->stack + nd->depth++; 17351cf2665bSAl Viro last->link = *link; 1736fceef393SAl Viro clear_delayed_call(&last->done); 1737fceef393SAl Viro nd->link_inode = inode; 17380450b2d1SAl Viro last->seq = seq; 1739d63ff28fSAl Viro return 1; 1740d63ff28fSAl Viro } 1741d63ff28fSAl Viro 17428f64fb1cSAl Viro enum {WALK_FOLLOW = 1, WALK_MORE = 2}; 174331d66bcdSAl Viro 17443ddcd056SLinus Torvalds /* 17453ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 17463ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 17473ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 17483ddcd056SLinus Torvalds * for the common case. 17493ddcd056SLinus Torvalds */ 17508f64fb1cSAl Viro static inline int step_into(struct nameidata *nd, struct path *path, 17518f64fb1cSAl Viro int flags, struct inode *inode, unsigned seq) 17523ddcd056SLinus Torvalds { 175331d66bcdSAl Viro if (!(flags & WALK_MORE) && nd->depth) 175431d66bcdSAl Viro put_link(nd); 17558f64fb1cSAl Viro if (likely(!d_is_symlink(path->dentry)) || 17568f64fb1cSAl Viro !(flags & WALK_FOLLOW || nd->flags & LOOKUP_FOLLOW)) { 17578f64fb1cSAl Viro /* not a symlink or should not follow */ 17588f64fb1cSAl Viro path_to_nameidata(path, nd); 17598f64fb1cSAl Viro nd->inode = inode; 17608f64fb1cSAl Viro nd->seq = seq; 1761d63ff28fSAl Viro return 0; 17628f64fb1cSAl Viro } 1763a7f77542SAl Viro /* make sure that d_is_symlink above matches inode */ 1764a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 17658f64fb1cSAl Viro if (read_seqcount_retry(&path->dentry->d_seq, seq)) 1766a7f77542SAl Viro return -ECHILD; 1767a7f77542SAl Viro } 17688f64fb1cSAl Viro return pick_link(nd, path, inode, seq); 17693ddcd056SLinus Torvalds } 17703ddcd056SLinus Torvalds 17714693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1772ce57dfc1SAl Viro { 1773caa85634SAl Viro struct path path; 1774ce57dfc1SAl Viro struct inode *inode; 1775254cf582SAl Viro unsigned seq; 1776ce57dfc1SAl Viro int err; 1777ce57dfc1SAl Viro /* 1778ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1779ce57dfc1SAl Viro * to be able to know about the current root directory and 1780ce57dfc1SAl Viro * parent relationships. 1781ce57dfc1SAl Viro */ 17824693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 17834693a547SAl Viro err = handle_dots(nd, nd->last_type); 17841c4ff1a8SAl Viro if (!(flags & WALK_MORE) && nd->depth) 17854693a547SAl Viro put_link(nd); 17864693a547SAl Viro return err; 17874693a547SAl Viro } 1788254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1789e9742b53SAl Viro if (unlikely(err <= 0)) { 1790697f514dSMiklos Szeredi if (err < 0) 1791f0a9ba70SAl Viro return err; 1792e3c13928SAl Viro path.dentry = lookup_slow(&nd->last, nd->path.dentry, 1793e3c13928SAl Viro nd->flags); 1794e3c13928SAl Viro if (IS_ERR(path.dentry)) 1795e3c13928SAl Viro return PTR_ERR(path.dentry); 17967500c38aSAl Viro 1797e3c13928SAl Viro path.mnt = nd->path.mnt; 1798e3c13928SAl Viro err = follow_managed(&path, nd); 1799e3c13928SAl Viro if (unlikely(err < 0)) 1800f0a9ba70SAl Viro return err; 1801697f514dSMiklos Szeredi 18027500c38aSAl Viro if (unlikely(d_is_negative(path.dentry))) { 18037500c38aSAl Viro path_to_nameidata(&path, nd); 18047500c38aSAl Viro return -ENOENT; 18057500c38aSAl Viro } 18067500c38aSAl Viro 1807254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1808d4565649SAl Viro inode = d_backing_inode(path.dentry); 1809766c4cbfSAl Viro } 1810697f514dSMiklos Szeredi 18118f64fb1cSAl Viro return step_into(nd, &path, flags, inode, seq); 1812ce57dfc1SAl Viro } 1813ce57dfc1SAl Viro 18141da177e4SLinus Torvalds /* 1815bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1816bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1817bfcfaa77SLinus Torvalds * 1818bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1819bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1820bfcfaa77SLinus Torvalds * fast. 1821bfcfaa77SLinus Torvalds * 1822bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1823bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1824bfcfaa77SLinus Torvalds * crossing operation. 1825bfcfaa77SLinus Torvalds * 1826bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1827bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1828bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1829bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1830bfcfaa77SLinus Torvalds */ 1831bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1832bfcfaa77SLinus Torvalds 1833f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1834bfcfaa77SLinus Torvalds 1835468a9428SGeorge Spelvin #ifdef HASH_MIX 1836bfcfaa77SLinus Torvalds 1837468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1838468a9428SGeorge Spelvin 1839468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 18402a18da7aSGeorge Spelvin /* 18412a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 18422a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 18432a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 18442a18da7aSGeorge Spelvin * and no temporaries. 18452a18da7aSGeorge Spelvin * 18462a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 18472a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 18482a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 18492a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 18502a18da7aSGeorge Spelvin * 18512a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 18522a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 18532a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 18542a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 18552a18da7aSGeorge Spelvin * 18562a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 18572a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 18582a18da7aSGeorge Spelvin * toggling any given output bit. 18592a18da7aSGeorge Spelvin * 18602a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 18612a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18622a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 18632a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 18642a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 18652a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 18662a18da7aSGeorge Spelvin * Perfect: 8192 258048 18672a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 18682a18da7aSGeorge Spelvin */ 18692a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18702a18da7aSGeorge Spelvin ( x ^= (a), \ 18712a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 18722a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 18732a18da7aSGeorge Spelvin y *= 9 ) 1874bfcfaa77SLinus Torvalds 18750fed3ac8SGeorge Spelvin /* 18762a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 18772a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 18782a18da7aSGeorge Spelvin * work done before the hash value is used. 18790fed3ac8SGeorge Spelvin */ 18802a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18810fed3ac8SGeorge Spelvin { 18822a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 18832a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 18842a18da7aSGeorge Spelvin return y >> 32; 18850fed3ac8SGeorge Spelvin } 18860fed3ac8SGeorge Spelvin 1887bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1888bfcfaa77SLinus Torvalds 18892a18da7aSGeorge Spelvin /* 18902a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 18912a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18922a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 18932a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 18942a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 18952a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 18962a18da7aSGeorge Spelvin * Perfect: 2048 31744 18972a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 18982a18da7aSGeorge Spelvin */ 18992a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 19002a18da7aSGeorge Spelvin ( x ^= (a), \ 19012a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 19022a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 19032a18da7aSGeorge Spelvin y *= 9 ) 1904bfcfaa77SLinus Torvalds 19052a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 19060fed3ac8SGeorge Spelvin { 19072a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 19082a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 19090fed3ac8SGeorge Spelvin } 19100fed3ac8SGeorge Spelvin 1911bfcfaa77SLinus Torvalds #endif 1912bfcfaa77SLinus Torvalds 19132a18da7aSGeorge Spelvin /* 19142a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 19152a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 19162a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 19172a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 19182a18da7aSGeorge Spelvin * finds the delimiter after the name. 19192a18da7aSGeorge Spelvin */ 19208387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 1921bfcfaa77SLinus Torvalds { 19228387ff25SLinus Torvalds unsigned long a, x = 0, y = (unsigned long)salt; 1923bfcfaa77SLinus Torvalds 1924bfcfaa77SLinus Torvalds for (;;) { 1925fcfd2fbfSGeorge Spelvin if (!len) 1926fcfd2fbfSGeorge Spelvin goto done; 1927e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1928bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1929bfcfaa77SLinus Torvalds break; 19302a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1931bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1932bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1933bfcfaa77SLinus Torvalds } 19342a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 1935bfcfaa77SLinus Torvalds done: 19362a18da7aSGeorge Spelvin return fold_hash(x, y); 1937bfcfaa77SLinus Torvalds } 1938bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1939bfcfaa77SLinus Torvalds 1940fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 19418387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 1942fcfd2fbfSGeorge Spelvin { 19438387ff25SLinus Torvalds unsigned long a = 0, x = 0, y = (unsigned long)salt; 19448387ff25SLinus Torvalds unsigned long adata, mask, len; 1945fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1946fcfd2fbfSGeorge Spelvin 19478387ff25SLinus Torvalds len = 0; 19488387ff25SLinus Torvalds goto inside; 19498387ff25SLinus Torvalds 1950fcfd2fbfSGeorge Spelvin do { 19512a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1952fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 19538387ff25SLinus Torvalds inside: 1954fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 1955fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 1956fcfd2fbfSGeorge Spelvin 1957fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 1958fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 19592a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 1960fcfd2fbfSGeorge Spelvin 19612a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1962fcfd2fbfSGeorge Spelvin } 1963fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 1964fcfd2fbfSGeorge Spelvin 1965bfcfaa77SLinus Torvalds /* 1966bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1967d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1968bfcfaa77SLinus Torvalds */ 19698387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 1970bfcfaa77SLinus Torvalds { 19718387ff25SLinus Torvalds unsigned long a = 0, b, x = 0, y = (unsigned long)salt; 19728387ff25SLinus Torvalds unsigned long adata, bdata, mask, len; 197336126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1974bfcfaa77SLinus Torvalds 19758387ff25SLinus Torvalds len = 0; 19768387ff25SLinus Torvalds goto inside; 19778387ff25SLinus Torvalds 1978bfcfaa77SLinus Torvalds do { 19792a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1980bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 19818387ff25SLinus Torvalds inside: 1982e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 198336126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 198436126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1985bfcfaa77SLinus Torvalds 198636126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 198736126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 198836126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 19892a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 199036126f8fSLinus Torvalds 19912a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1992bfcfaa77SLinus Torvalds } 1993bfcfaa77SLinus Torvalds 19942a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 1995bfcfaa77SLinus Torvalds 1996fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 19978387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 19980145acc2SLinus Torvalds { 19998387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 20000145acc2SLinus Torvalds while (len--) 2001fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 20020145acc2SLinus Torvalds return end_name_hash(hash); 20030145acc2SLinus Torvalds } 2004ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 20050145acc2SLinus Torvalds 2006fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 20078387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2008fcfd2fbfSGeorge Spelvin { 20098387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2010fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 2011fcfd2fbfSGeorge Spelvin 2012fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 2013e0ab7af9SGeorge Spelvin while (c) { 2014fcfd2fbfSGeorge Spelvin len++; 2015fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 2016fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 2017e0ab7af9SGeorge Spelvin } 2018fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 2019fcfd2fbfSGeorge Spelvin } 2020f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2021fcfd2fbfSGeorge Spelvin 20223ddcd056SLinus Torvalds /* 2023200e9ef7SLinus Torvalds * We know there's a real path component here of at least 2024200e9ef7SLinus Torvalds * one character. 2025200e9ef7SLinus Torvalds */ 20268387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2027200e9ef7SLinus Torvalds { 20288387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2029200e9ef7SLinus Torvalds unsigned long len = 0, c; 2030200e9ef7SLinus Torvalds 2031200e9ef7SLinus Torvalds c = (unsigned char)*name; 2032200e9ef7SLinus Torvalds do { 2033200e9ef7SLinus Torvalds len++; 2034200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2035200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2036200e9ef7SLinus Torvalds } while (c && c != '/'); 2037d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2038200e9ef7SLinus Torvalds } 2039200e9ef7SLinus Torvalds 2040bfcfaa77SLinus Torvalds #endif 2041bfcfaa77SLinus Torvalds 2042200e9ef7SLinus Torvalds /* 20431da177e4SLinus Torvalds * Name resolution. 2044ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2045ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 20461da177e4SLinus Torvalds * 2047ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2048ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 20491da177e4SLinus Torvalds */ 20506de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 20511da177e4SLinus Torvalds { 20521da177e4SLinus Torvalds int err; 20531da177e4SLinus Torvalds 20541da177e4SLinus Torvalds while (*name=='/') 20551da177e4SLinus Torvalds name++; 20561da177e4SLinus Torvalds if (!*name) 20579e18f10aSAl Viro return 0; 20581da177e4SLinus Torvalds 20591da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 20601da177e4SLinus Torvalds for(;;) { 2061d6bb3e90SLinus Torvalds u64 hash_len; 2062fe479a58SAl Viro int type; 20631da177e4SLinus Torvalds 206452094c8aSAl Viro err = may_lookup(nd); 20651da177e4SLinus Torvalds if (err) 20663595e234SAl Viro return err; 20671da177e4SLinus Torvalds 20688387ff25SLinus Torvalds hash_len = hash_name(nd->path.dentry, name); 20691da177e4SLinus Torvalds 2070fe479a58SAl Viro type = LAST_NORM; 2071d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2072fe479a58SAl Viro case 2: 2073200e9ef7SLinus Torvalds if (name[1] == '.') { 2074fe479a58SAl Viro type = LAST_DOTDOT; 207516c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 207616c2cd71SAl Viro } 2077fe479a58SAl Viro break; 2078fe479a58SAl Viro case 1: 2079fe479a58SAl Viro type = LAST_DOT; 2080fe479a58SAl Viro } 20815a202bcdSAl Viro if (likely(type == LAST_NORM)) { 20825a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 208316c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 20845a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2085a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2086da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 20875a202bcdSAl Viro if (err < 0) 20883595e234SAl Viro return err; 2089d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2090d6bb3e90SLinus Torvalds name = this.name; 20915a202bcdSAl Viro } 20925a202bcdSAl Viro } 2093fe479a58SAl Viro 2094d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2095d6bb3e90SLinus Torvalds nd->last.name = name; 20965f4a6a69SAl Viro nd->last_type = type; 20975f4a6a69SAl Viro 2098d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2099d6bb3e90SLinus Torvalds if (!*name) 2100bdf6cbf1SAl Viro goto OK; 2101200e9ef7SLinus Torvalds /* 2102200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2103200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2104200e9ef7SLinus Torvalds */ 2105200e9ef7SLinus Torvalds do { 2106d6bb3e90SLinus Torvalds name++; 2107d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 21088620c238SAl Viro if (unlikely(!*name)) { 21098620c238SAl Viro OK: 2110368ee9baSAl Viro /* pathname body, done */ 21118620c238SAl Viro if (!nd->depth) 21128620c238SAl Viro return 0; 21138620c238SAl Viro name = nd->stack[nd->depth - 1].name; 2114368ee9baSAl Viro /* trailing symlink, done */ 21158620c238SAl Viro if (!name) 21168620c238SAl Viro return 0; 21178620c238SAl Viro /* last component of nested symlink */ 21188f64fb1cSAl Viro err = walk_component(nd, WALK_FOLLOW); 21191c4ff1a8SAl Viro } else { 21201c4ff1a8SAl Viro /* not the last component */ 21218f64fb1cSAl Viro err = walk_component(nd, WALK_FOLLOW | WALK_MORE); 21228620c238SAl Viro } 2123ce57dfc1SAl Viro if (err < 0) 21243595e234SAl Viro return err; 2125fe479a58SAl Viro 2126ce57dfc1SAl Viro if (err) { 2127626de996SAl Viro const char *s = get_link(nd); 21285a460275SAl Viro 2129a1c83681SViresh Kumar if (IS_ERR(s)) 21303595e234SAl Viro return PTR_ERR(s); 2131172a39a0SAl Viro err = 0; 213212b09578SAl Viro if (unlikely(!s)) { 213312b09578SAl Viro /* jumped */ 2134b9ff4429SAl Viro put_link(nd); 213512b09578SAl Viro } else { 2136071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 213732cd7468SAl Viro name = s; 21389e18f10aSAl Viro continue; 213948c8b0c5SAl Viro } 214031e6b01fSNick Piggin } 214197242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 214297242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 21434675ac39SAl Viro if (unlazy_walk(nd)) 214497242f99SAl Viro return -ECHILD; 214597242f99SAl Viro } 21463595e234SAl Viro return -ENOTDIR; 21475f4a6a69SAl Viro } 2148ce57dfc1SAl Viro } 214997242f99SAl Viro } 21501da177e4SLinus Torvalds 2151c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 215231e6b01fSNick Piggin { 2153c8a53ee5SAl Viro const char *s = nd->name->name; 215431e6b01fSNick Piggin 2155c0eb027eSLinus Torvalds if (!*s) 2156c0eb027eSLinus Torvalds flags &= ~LOOKUP_RCU; 2157c0eb027eSLinus Torvalds 215831e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 2159980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 216031e6b01fSNick Piggin nd->depth = 0; 21615b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2162b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2163b18825a7SDavid Howells struct inode *inode = root->d_inode; 216493893862SAl Viro if (*s && unlikely(!d_can_lookup(root))) 2165368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 21665b6ca027SAl Viro nd->path = nd->root; 21675b6ca027SAl Viro nd->inode = inode; 21685b6ca027SAl Viro if (flags & LOOKUP_RCU) { 21698b61e74fSAl Viro rcu_read_lock(); 21705b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 21718f47a016SAl Viro nd->root_seq = nd->seq; 217248a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 21735b6ca027SAl Viro } else { 21745b6ca027SAl Viro path_get(&nd->path); 21755b6ca027SAl Viro } 2176368ee9baSAl Viro return s; 21775b6ca027SAl Viro } 21785b6ca027SAl Viro 217931e6b01fSNick Piggin nd->root.mnt = NULL; 2180248fb5b9SAl Viro nd->path.mnt = NULL; 2181248fb5b9SAl Viro nd->path.dentry = NULL; 218231e6b01fSNick Piggin 218348a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 2184fd2f7cb5SAl Viro if (*s == '/') { 21859e6697e2SAl Viro if (flags & LOOKUP_RCU) 21868b61e74fSAl Viro rcu_read_lock(); 2187e41f7d4eSAl Viro set_root(nd); 2188248fb5b9SAl Viro if (likely(!nd_jump_root(nd))) 2189ef55d917SAl Viro return s; 2190ef55d917SAl Viro nd->root.mnt = NULL; 2191ef55d917SAl Viro rcu_read_unlock(); 2192ef55d917SAl Viro return ERR_PTR(-ECHILD); 2193c8a53ee5SAl Viro } else if (nd->dfd == AT_FDCWD) { 2194e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 219531e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2196c28cc364SNick Piggin unsigned seq; 219731e6b01fSNick Piggin 21988b61e74fSAl Viro rcu_read_lock(); 219931e6b01fSNick Piggin 2200c28cc364SNick Piggin do { 2201c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 220231e6b01fSNick Piggin nd->path = fs->pwd; 2203ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2204c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2205c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2206e41f7d4eSAl Viro } else { 2207e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2208ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2209e41f7d4eSAl Viro } 2210ef55d917SAl Viro return s; 221131e6b01fSNick Piggin } else { 2212582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2213c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 221431e6b01fSNick Piggin struct dentry *dentry; 221531e6b01fSNick Piggin 22162903ff01SAl Viro if (!f.file) 2217368ee9baSAl Viro return ERR_PTR(-EBADF); 221831e6b01fSNick Piggin 22192903ff01SAl Viro dentry = f.file->f_path.dentry; 222031e6b01fSNick Piggin 2221fd2f7cb5SAl Viro if (*s) { 222244b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 22232903ff01SAl Viro fdput(f); 2224368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2225f52e0c11SAl Viro } 22262903ff01SAl Viro } 22272903ff01SAl Viro 22282903ff01SAl Viro nd->path = f.file->f_path; 2229e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 22308b61e74fSAl Viro rcu_read_lock(); 223134a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 223234a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22335590ff0dSUlrich Drepper } else { 22342903ff01SAl Viro path_get(&nd->path); 223534a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 22361da177e4SLinus Torvalds } 223734a26b99SAl Viro fdput(f); 2238368ee9baSAl Viro return s; 2239e41f7d4eSAl Viro } 22409b4a9b14SAl Viro } 22419b4a9b14SAl Viro 22423bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 224395fa25d9SAl Viro { 224495fa25d9SAl Viro const char *s; 2245fec2fa24SAl Viro int error = may_follow_link(nd); 2246deb106c6SAl Viro if (unlikely(error)) 22473bdba28bSAl Viro return ERR_PTR(error); 224895fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2249fab51e8aSAl Viro nd->stack[0].name = NULL; 22503b2e7f75SAl Viro s = get_link(nd); 2251deb106c6SAl Viro return s ? s : ""; 225295fa25d9SAl Viro } 225395fa25d9SAl Viro 2254caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2255bd92d7feSAl Viro { 2256bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2257bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2258bd92d7feSAl Viro 2259bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 22601c4ff1a8SAl Viro return walk_component(nd, 0); 2261bd92d7feSAl Viro } 2262bd92d7feSAl Viro 22634f757f3cSAl Viro static int handle_lookup_down(struct nameidata *nd) 22644f757f3cSAl Viro { 22654f757f3cSAl Viro struct path path = nd->path; 22664f757f3cSAl Viro struct inode *inode = nd->inode; 22674f757f3cSAl Viro unsigned seq = nd->seq; 22684f757f3cSAl Viro int err; 22694f757f3cSAl Viro 22704f757f3cSAl Viro if (nd->flags & LOOKUP_RCU) { 22714f757f3cSAl Viro /* 22724f757f3cSAl Viro * don't bother with unlazy_walk on failure - we are 22734f757f3cSAl Viro * at the very beginning of walk, so we lose nothing 22744f757f3cSAl Viro * if we simply redo everything in non-RCU mode 22754f757f3cSAl Viro */ 22764f757f3cSAl Viro if (unlikely(!__follow_mount_rcu(nd, &path, &inode, &seq))) 22774f757f3cSAl Viro return -ECHILD; 22784f757f3cSAl Viro } else { 22794f757f3cSAl Viro dget(path.dentry); 22804f757f3cSAl Viro err = follow_managed(&path, nd); 22814f757f3cSAl Viro if (unlikely(err < 0)) 22824f757f3cSAl Viro return err; 22834f757f3cSAl Viro inode = d_backing_inode(path.dentry); 22844f757f3cSAl Viro seq = 0; 22854f757f3cSAl Viro } 22864f757f3cSAl Viro path_to_nameidata(&path, nd); 22874f757f3cSAl Viro nd->inode = inode; 22884f757f3cSAl Viro nd->seq = seq; 22894f757f3cSAl Viro return 0; 22904f757f3cSAl Viro } 22914f757f3cSAl Viro 22929b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2293c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 22949b4a9b14SAl Viro { 2295c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2296bd92d7feSAl Viro int err; 229731e6b01fSNick Piggin 2298368ee9baSAl Viro if (IS_ERR(s)) 2299368ee9baSAl Viro return PTR_ERR(s); 23004f757f3cSAl Viro 23014f757f3cSAl Viro if (unlikely(flags & LOOKUP_DOWN)) { 23024f757f3cSAl Viro err = handle_lookup_down(nd); 23034f757f3cSAl Viro if (unlikely(err < 0)) { 23044f757f3cSAl Viro terminate_walk(nd); 23054f757f3cSAl Viro return err; 23064f757f3cSAl Viro } 23074f757f3cSAl Viro } 23084f757f3cSAl Viro 23093bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 23103bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 23113bdba28bSAl Viro s = trailing_symlink(nd); 23123bdba28bSAl Viro if (IS_ERR(s)) { 23133bdba28bSAl Viro err = PTR_ERR(s); 23146d7b5aaeSAl Viro break; 2315bd92d7feSAl Viro } 2316bd92d7feSAl Viro } 23179f1fafeeSAl Viro if (!err) 23189f1fafeeSAl Viro err = complete_walk(nd); 2319bd92d7feSAl Viro 2320deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2321deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2322bd23a539SAl Viro err = -ENOTDIR; 2323625b6d10SAl Viro if (!err) { 2324625b6d10SAl Viro *path = nd->path; 2325625b6d10SAl Viro nd->path.mnt = NULL; 2326625b6d10SAl Viro nd->path.dentry = NULL; 2327625b6d10SAl Viro } 2328deb106c6SAl Viro terminate_walk(nd); 2329bd92d7feSAl Viro return err; 233031e6b01fSNick Piggin } 233131e6b01fSNick Piggin 2332625b6d10SAl Viro static int filename_lookup(int dfd, struct filename *name, unsigned flags, 23339ad1aaa6SAl Viro struct path *path, struct path *root) 2334873f1eedSJeff Layton { 2335894bc8c4SAl Viro int retval; 23369883d185SAl Viro struct nameidata nd; 2337abc9f5beSAl Viro if (IS_ERR(name)) 2338abc9f5beSAl Viro return PTR_ERR(name); 23399ad1aaa6SAl Viro if (unlikely(root)) { 23409ad1aaa6SAl Viro nd.root = *root; 23419ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 23429ad1aaa6SAl Viro } 23439883d185SAl Viro set_nameidata(&nd, dfd, name); 2344c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2345873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2346c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2347873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2348c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2349873f1eedSJeff Layton 2350873f1eedSJeff Layton if (likely(!retval)) 2351625b6d10SAl Viro audit_inode(name, path->dentry, flags & LOOKUP_PARENT); 23529883d185SAl Viro restore_nameidata(); 2353e4bd1c1aSAl Viro putname(name); 2354873f1eedSJeff Layton return retval; 2355873f1eedSJeff Layton } 2356873f1eedSJeff Layton 23578bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2358c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2359391172c4SAl Viro struct path *parent) 23608bcb77faSAl Viro { 2361c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2362368ee9baSAl Viro int err; 2363368ee9baSAl Viro if (IS_ERR(s)) 2364368ee9baSAl Viro return PTR_ERR(s); 2365368ee9baSAl Viro err = link_path_walk(s, nd); 23668bcb77faSAl Viro if (!err) 23678bcb77faSAl Viro err = complete_walk(nd); 2368391172c4SAl Viro if (!err) { 2369391172c4SAl Viro *parent = nd->path; 2370391172c4SAl Viro nd->path.mnt = NULL; 2371391172c4SAl Viro nd->path.dentry = NULL; 2372391172c4SAl Viro } 2373deb106c6SAl Viro terminate_walk(nd); 23748bcb77faSAl Viro return err; 23758bcb77faSAl Viro } 23768bcb77faSAl Viro 23775c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2378391172c4SAl Viro unsigned int flags, struct path *parent, 2379391172c4SAl Viro struct qstr *last, int *type) 23808bcb77faSAl Viro { 23818bcb77faSAl Viro int retval; 23829883d185SAl Viro struct nameidata nd; 23838bcb77faSAl Viro 23845c31b6ceSAl Viro if (IS_ERR(name)) 23855c31b6ceSAl Viro return name; 23869883d185SAl Viro set_nameidata(&nd, dfd, name); 2387c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 23888bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2389c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 23908bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2391c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2392391172c4SAl Viro if (likely(!retval)) { 2393391172c4SAl Viro *last = nd.last; 2394391172c4SAl Viro *type = nd.last_type; 2395391172c4SAl Viro audit_inode(name, parent->dentry, LOOKUP_PARENT); 23965c31b6ceSAl Viro } else { 23975c31b6ceSAl Viro putname(name); 23985c31b6ceSAl Viro name = ERR_PTR(retval); 2399391172c4SAl Viro } 24009883d185SAl Viro restore_nameidata(); 24015c31b6ceSAl Viro return name; 24028bcb77faSAl Viro } 24038bcb77faSAl Viro 240479714f72SAl Viro /* does lookup, returns the object with parent locked */ 240579714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 24065590ff0dSUlrich Drepper { 24075c31b6ceSAl Viro struct filename *filename; 24085c31b6ceSAl Viro struct dentry *d; 2409391172c4SAl Viro struct qstr last; 2410391172c4SAl Viro int type; 241151689104SPaul Moore 24125c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 24135c31b6ceSAl Viro &last, &type); 241451689104SPaul Moore if (IS_ERR(filename)) 241551689104SPaul Moore return ERR_CAST(filename); 24165c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2417391172c4SAl Viro path_put(path); 24185c31b6ceSAl Viro putname(filename); 24195c31b6ceSAl Viro return ERR_PTR(-EINVAL); 242079714f72SAl Viro } 24215955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2422391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 242379714f72SAl Viro if (IS_ERR(d)) { 24245955102cSAl Viro inode_unlock(path->dentry->d_inode); 2425391172c4SAl Viro path_put(path); 242679714f72SAl Viro } 242751689104SPaul Moore putname(filename); 242879714f72SAl Viro return d; 24295590ff0dSUlrich Drepper } 24305590ff0dSUlrich Drepper 2431d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2432d1811465SAl Viro { 2433abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2434abc9f5beSAl Viro flags, path, NULL); 2435d1811465SAl Viro } 24364d359507SAl Viro EXPORT_SYMBOL(kern_path); 2437d1811465SAl Viro 243816f18200SJosef 'Jeff' Sipek /** 243916f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 244016f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 244116f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 244216f18200SJosef 'Jeff' Sipek * @name: pointer to file name 244316f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2444e0a01249SAl Viro * @path: pointer to struct path to fill 244516f18200SJosef 'Jeff' Sipek */ 244616f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 244716f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2448e0a01249SAl Viro struct path *path) 244916f18200SJosef 'Jeff' Sipek { 24509ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 24519ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2452abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2453abc9f5beSAl Viro flags , path, &root); 245416f18200SJosef 'Jeff' Sipek } 24554d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 245616f18200SJosef 'Jeff' Sipek 2457eead1911SChristoph Hellwig /** 2458a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2459eead1911SChristoph Hellwig * @name: pathname component to lookup 2460eead1911SChristoph Hellwig * @base: base directory to lookup from 2461eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2462eead1911SChristoph Hellwig * 2463a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 24649e7543e9SAl Viro * not be called by generic code. 2465bbddca8eSNeilBrown * 2466bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2467eead1911SChristoph Hellwig */ 2468057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2469057f6c01SJames Morris { 2470057f6c01SJames Morris struct qstr this; 24716a96ba54SAl Viro unsigned int c; 2472cda309deSMiklos Szeredi int err; 2473057f6c01SJames Morris 24745955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 24752f9092e1SDavid Woodhouse 24766a96ba54SAl Viro this.name = name; 24776a96ba54SAl Viro this.len = len; 24788387ff25SLinus Torvalds this.hash = full_name_hash(base, name, len); 24796a96ba54SAl Viro if (!len) 24806a96ba54SAl Viro return ERR_PTR(-EACCES); 24816a96ba54SAl Viro 248221d8a15aSAl Viro if (unlikely(name[0] == '.')) { 248321d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 248421d8a15aSAl Viro return ERR_PTR(-EACCES); 248521d8a15aSAl Viro } 248621d8a15aSAl Viro 24876a96ba54SAl Viro while (len--) { 24886a96ba54SAl Viro c = *(const unsigned char *)name++; 24896a96ba54SAl Viro if (c == '/' || c == '\0') 24906a96ba54SAl Viro return ERR_PTR(-EACCES); 24916a96ba54SAl Viro } 24925a202bcdSAl Viro /* 24935a202bcdSAl Viro * See if the low-level filesystem might want 24945a202bcdSAl Viro * to use its own hash.. 24955a202bcdSAl Viro */ 24965a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2497da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 24985a202bcdSAl Viro if (err < 0) 24995a202bcdSAl Viro return ERR_PTR(err); 25005a202bcdSAl Viro } 2501eead1911SChristoph Hellwig 2502cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2503cda309deSMiklos Szeredi if (err) 2504cda309deSMiklos Szeredi return ERR_PTR(err); 2505cda309deSMiklos Szeredi 250672bd866aSAl Viro return __lookup_hash(&this, base, 0); 2507057f6c01SJames Morris } 25084d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2509057f6c01SJames Morris 2510bbddca8eSNeilBrown /** 2511bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2512bbddca8eSNeilBrown * @name: pathname component to lookup 2513bbddca8eSNeilBrown * @base: base directory to lookup from 2514bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2515bbddca8eSNeilBrown * 2516bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2517bbddca8eSNeilBrown * not be called by generic code. 2518bbddca8eSNeilBrown * 2519bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2520bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2521bbddca8eSNeilBrown */ 2522bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2523bbddca8eSNeilBrown struct dentry *base, int len) 2524bbddca8eSNeilBrown { 2525bbddca8eSNeilBrown struct qstr this; 2526bbddca8eSNeilBrown unsigned int c; 2527bbddca8eSNeilBrown int err; 252820d00ee8SLinus Torvalds struct dentry *ret; 2529bbddca8eSNeilBrown 2530bbddca8eSNeilBrown this.name = name; 2531bbddca8eSNeilBrown this.len = len; 25328387ff25SLinus Torvalds this.hash = full_name_hash(base, name, len); 2533bbddca8eSNeilBrown if (!len) 2534bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2535bbddca8eSNeilBrown 2536bbddca8eSNeilBrown if (unlikely(name[0] == '.')) { 2537bbddca8eSNeilBrown if (len < 2 || (len == 2 && name[1] == '.')) 2538bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2539bbddca8eSNeilBrown } 2540bbddca8eSNeilBrown 2541bbddca8eSNeilBrown while (len--) { 2542bbddca8eSNeilBrown c = *(const unsigned char *)name++; 2543bbddca8eSNeilBrown if (c == '/' || c == '\0') 2544bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2545bbddca8eSNeilBrown } 2546bbddca8eSNeilBrown /* 2547bbddca8eSNeilBrown * See if the low-level filesystem might want 2548bbddca8eSNeilBrown * to use its own hash.. 2549bbddca8eSNeilBrown */ 2550bbddca8eSNeilBrown if (base->d_flags & DCACHE_OP_HASH) { 2551bbddca8eSNeilBrown int err = base->d_op->d_hash(base, &this); 2552bbddca8eSNeilBrown if (err < 0) 2553bbddca8eSNeilBrown return ERR_PTR(err); 2554bbddca8eSNeilBrown } 2555bbddca8eSNeilBrown 2556bbddca8eSNeilBrown err = inode_permission(base->d_inode, MAY_EXEC); 2557bbddca8eSNeilBrown if (err) 2558bbddca8eSNeilBrown return ERR_PTR(err); 2559bbddca8eSNeilBrown 256020d00ee8SLinus Torvalds ret = lookup_dcache(&this, base, 0); 256120d00ee8SLinus Torvalds if (!ret) 256220d00ee8SLinus Torvalds ret = lookup_slow(&this, base, 0); 256320d00ee8SLinus Torvalds return ret; 2564bbddca8eSNeilBrown } 2565bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2566bbddca8eSNeilBrown 2567eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2568eedf265aSEric W. Biederman int path_pts(struct path *path) 2569eedf265aSEric W. Biederman { 2570eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2571eedf265aSEric W. Biederman * the input path. 2572eedf265aSEric W. Biederman */ 2573eedf265aSEric W. Biederman struct dentry *child, *parent; 2574eedf265aSEric W. Biederman struct qstr this; 2575eedf265aSEric W. Biederman int ret; 2576eedf265aSEric W. Biederman 2577eedf265aSEric W. Biederman ret = path_parent_directory(path); 2578eedf265aSEric W. Biederman if (ret) 2579eedf265aSEric W. Biederman return ret; 2580eedf265aSEric W. Biederman 2581eedf265aSEric W. Biederman parent = path->dentry; 2582eedf265aSEric W. Biederman this.name = "pts"; 2583eedf265aSEric W. Biederman this.len = 3; 2584eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2585eedf265aSEric W. Biederman if (!child) 2586eedf265aSEric W. Biederman return -ENOENT; 2587eedf265aSEric W. Biederman 2588eedf265aSEric W. Biederman path->dentry = child; 2589eedf265aSEric W. Biederman dput(parent); 2590eedf265aSEric W. Biederman follow_mount(path); 2591eedf265aSEric W. Biederman return 0; 2592eedf265aSEric W. Biederman } 2593eedf265aSEric W. Biederman #endif 2594eedf265aSEric W. Biederman 25951fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 25961fa1e7f6SAndy Whitcroft struct path *path, int *empty) 25971da177e4SLinus Torvalds { 2598abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2599abc9f5beSAl Viro flags, path, NULL); 26001da177e4SLinus Torvalds } 2601b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 26021fa1e7f6SAndy Whitcroft 26038033426eSJeff Layton /** 2604197df04cSAl Viro * mountpoint_last - look up last component for umount 26058033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 26068033426eSJeff Layton * 26078033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 26088033426eSJeff Layton * need to resolve the path without doing any revalidation. 26098033426eSJeff Layton * 26108033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 26118033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 26128033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 26138033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 26148033426eSJeff Layton * bogus and it doesn't exist. 26158033426eSJeff Layton * 26168033426eSJeff Layton * Returns: 26178033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 2618ba8f4613SAl Viro * lookup found a negative dentry. 26198033426eSJeff Layton * 2620ba8f4613SAl Viro * 0: if we successfully resolved nd->last and found it to not to be a 2621ba8f4613SAl Viro * symlink that needs to be followed. 26228033426eSJeff Layton * 26238033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 2624ba8f4613SAl Viro * that needs to be followed. 26258033426eSJeff Layton */ 26268033426eSJeff Layton static int 2627ba8f4613SAl Viro mountpoint_last(struct nameidata *nd) 26288033426eSJeff Layton { 26298033426eSJeff Layton int error = 0; 26308033426eSJeff Layton struct dentry *dir = nd->path.dentry; 2631ba8f4613SAl Viro struct path path; 26328033426eSJeff Layton 263335759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 263435759521SAl Viro if (nd->flags & LOOKUP_RCU) { 26354675ac39SAl Viro if (unlazy_walk(nd)) 2636deb106c6SAl Viro return -ECHILD; 26378033426eSJeff Layton } 26388033426eSJeff Layton 26398033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 26408033426eSJeff Layton 26418033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 26428033426eSJeff Layton error = handle_dots(nd, nd->last_type); 264335759521SAl Viro if (error) 2644deb106c6SAl Viro return error; 2645ba8f4613SAl Viro path.dentry = dget(nd->path.dentry); 2646949a852eSAl Viro } else { 2647ba8f4613SAl Viro path.dentry = d_lookup(dir, &nd->last); 2648ba8f4613SAl Viro if (!path.dentry) { 26498033426eSJeff Layton /* 2650949a852eSAl Viro * No cached dentry. Mounted dentries are pinned in the 2651949a852eSAl Viro * cache, so that means that this dentry is probably 2652949a852eSAl Viro * a symlink or the path doesn't actually point 2653949a852eSAl Viro * to a mounted dentry. 26548033426eSJeff Layton */ 2655ba8f4613SAl Viro path.dentry = lookup_slow(&nd->last, dir, 2656949a852eSAl Viro nd->flags | LOOKUP_NO_REVAL); 2657ba8f4613SAl Viro if (IS_ERR(path.dentry)) 2658ba8f4613SAl Viro return PTR_ERR(path.dentry); 26598033426eSJeff Layton } 2660bcceeebaSDave Jones } 2661ba8f4613SAl Viro if (d_is_negative(path.dentry)) { 2662ba8f4613SAl Viro dput(path.dentry); 2663deb106c6SAl Viro return -ENOENT; 266435759521SAl Viro } 2665ba8f4613SAl Viro path.mnt = nd->path.mnt; 26668f64fb1cSAl Viro return step_into(nd, &path, 0, d_backing_inode(path.dentry), 0); 26678033426eSJeff Layton } 26688033426eSJeff Layton 26698033426eSJeff Layton /** 2670197df04cSAl Viro * path_mountpoint - look up a path to be umounted 26712a78b857SMasanari Iida * @nd: lookup context 26728033426eSJeff Layton * @flags: lookup flags 2673c8a53ee5SAl Viro * @path: pointer to container for result 26748033426eSJeff Layton * 26758033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2676606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 26778033426eSJeff Layton */ 26788033426eSJeff Layton static int 2679c8a53ee5SAl Viro path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) 26808033426eSJeff Layton { 2681c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2682368ee9baSAl Viro int err; 2683368ee9baSAl Viro if (IS_ERR(s)) 2684368ee9baSAl Viro return PTR_ERR(s); 26853bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 2686ba8f4613SAl Viro (err = mountpoint_last(nd)) > 0) { 26873bdba28bSAl Viro s = trailing_symlink(nd); 26883bdba28bSAl Viro if (IS_ERR(s)) { 26893bdba28bSAl Viro err = PTR_ERR(s); 26908033426eSJeff Layton break; 26918033426eSJeff Layton } 26923bdba28bSAl Viro } 2693ba8f4613SAl Viro if (!err) { 2694ba8f4613SAl Viro *path = nd->path; 2695ba8f4613SAl Viro nd->path.mnt = NULL; 2696ba8f4613SAl Viro nd->path.dentry = NULL; 2697ba8f4613SAl Viro follow_mount(path); 2698ba8f4613SAl Viro } 2699deb106c6SAl Viro terminate_walk(nd); 27008033426eSJeff Layton return err; 27018033426eSJeff Layton } 27028033426eSJeff Layton 27032d864651SAl Viro static int 2704668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 27052d864651SAl Viro unsigned int flags) 27062d864651SAl Viro { 27079883d185SAl Viro struct nameidata nd; 2708cbaab2dbSAl Viro int error; 2709668696dcSAl Viro if (IS_ERR(name)) 2710668696dcSAl Viro return PTR_ERR(name); 27119883d185SAl Viro set_nameidata(&nd, dfd, name); 2712c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); 27132d864651SAl Viro if (unlikely(error == -ECHILD)) 2714c8a53ee5SAl Viro error = path_mountpoint(&nd, flags, path); 27152d864651SAl Viro if (unlikely(error == -ESTALE)) 2716c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); 27172d864651SAl Viro if (likely(!error)) 2718668696dcSAl Viro audit_inode(name, path->dentry, 0); 27199883d185SAl Viro restore_nameidata(); 2720668696dcSAl Viro putname(name); 27212d864651SAl Viro return error; 27222d864651SAl Viro } 27232d864651SAl Viro 27248033426eSJeff Layton /** 2725197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 27268033426eSJeff Layton * @dfd: directory file descriptor 27278033426eSJeff Layton * @name: pathname from userland 27288033426eSJeff Layton * @flags: lookup flags 27298033426eSJeff Layton * @path: pointer to container to hold result 27308033426eSJeff Layton * 27318033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 27328033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 27338033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 27348033426eSJeff Layton * and avoid revalidating the last component. 27358033426eSJeff Layton * 27368033426eSJeff Layton * Returns 0 and populates "path" on success. 27378033426eSJeff Layton */ 27388033426eSJeff Layton int 2739197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 27408033426eSJeff Layton struct path *path) 27418033426eSJeff Layton { 2742cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 27438033426eSJeff Layton } 27448033426eSJeff Layton 27452d864651SAl Viro int 27462d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 27472d864651SAl Viro unsigned int flags) 27482d864651SAl Viro { 2749cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 27502d864651SAl Viro } 27512d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 27522d864651SAl Viro 2753cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 27541da177e4SLinus Torvalds { 27558e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2756da9592edSDavid Howells 27578e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 27581da177e4SLinus Torvalds return 0; 27598e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 27601da177e4SLinus Torvalds return 0; 276123adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 27621da177e4SLinus Torvalds } 2763cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 27641da177e4SLinus Torvalds 27651da177e4SLinus Torvalds /* 27661da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 27671da177e4SLinus Torvalds * whether the type of victim is right. 27681da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 27691da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 27701da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 27711da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 27721da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 27731da177e4SLinus Torvalds * a. be owner of dir, or 27741da177e4SLinus Torvalds * b. be owner of victim, or 27751da177e4SLinus Torvalds * c. have CAP_FOWNER capability 27761da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 27771da177e4SLinus Torvalds * links pointing to it. 27780bd23d09SEric W. Biederman * 7. If the victim has an unknown uid or gid we can't change the inode. 27790bd23d09SEric W. Biederman * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. 27800bd23d09SEric W. Biederman * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. 27810bd23d09SEric W. Biederman * 10. We can't remove a root or mountpoint. 27820bd23d09SEric W. Biederman * 11. We don't allow removal of NFS sillyrenamed files; it's handled by 27831da177e4SLinus Torvalds * nfs_async_unlink(). 27841da177e4SLinus Torvalds */ 2785b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 27861da177e4SLinus Torvalds { 278763afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 27881da177e4SLinus Torvalds int error; 27891da177e4SLinus Torvalds 2790b18825a7SDavid Howells if (d_is_negative(victim)) 27911da177e4SLinus Torvalds return -ENOENT; 2792b18825a7SDavid Howells BUG_ON(!inode); 27931da177e4SLinus Torvalds 27941da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 27954fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 27961da177e4SLinus Torvalds 2797f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 27981da177e4SLinus Torvalds if (error) 27991da177e4SLinus Torvalds return error; 28001da177e4SLinus Torvalds if (IS_APPEND(dir)) 28011da177e4SLinus Torvalds return -EPERM; 2802b18825a7SDavid Howells 2803b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 28040bd23d09SEric W. Biederman IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) 28051da177e4SLinus Torvalds return -EPERM; 28061da177e4SLinus Torvalds if (isdir) { 280744b1d530SMiklos Szeredi if (!d_is_dir(victim)) 28081da177e4SLinus Torvalds return -ENOTDIR; 28091da177e4SLinus Torvalds if (IS_ROOT(victim)) 28101da177e4SLinus Torvalds return -EBUSY; 281144b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 28121da177e4SLinus Torvalds return -EISDIR; 28131da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 28141da177e4SLinus Torvalds return -ENOENT; 28151da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 28161da177e4SLinus Torvalds return -EBUSY; 28171da177e4SLinus Torvalds return 0; 28181da177e4SLinus Torvalds } 28191da177e4SLinus Torvalds 28201da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 28211da177e4SLinus Torvalds * dir. 28221da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 28231da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 28241da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 2825036d5236SEric W. Biederman * 3. We can't do it if the fs can't represent the fsuid or fsgid. 2826036d5236SEric W. Biederman * 4. We should have write and exec permissions on dir 2827036d5236SEric W. Biederman * 5. We can't do it if dir is immutable (done in permission()) 28281da177e4SLinus Torvalds */ 2829a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 28301da177e4SLinus Torvalds { 2831036d5236SEric W. Biederman struct user_namespace *s_user_ns; 283214e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 28331da177e4SLinus Torvalds if (child->d_inode) 28341da177e4SLinus Torvalds return -EEXIST; 28351da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 28361da177e4SLinus Torvalds return -ENOENT; 2837036d5236SEric W. Biederman s_user_ns = dir->i_sb->s_user_ns; 2838036d5236SEric W. Biederman if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 2839036d5236SEric W. Biederman !kgid_has_mapping(s_user_ns, current_fsgid())) 2840036d5236SEric W. Biederman return -EOVERFLOW; 2841f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 28421da177e4SLinus Torvalds } 28431da177e4SLinus Torvalds 28441da177e4SLinus Torvalds /* 28451da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 28461da177e4SLinus Torvalds */ 28471da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 28481da177e4SLinus Torvalds { 28491da177e4SLinus Torvalds struct dentry *p; 28501da177e4SLinus Torvalds 28511da177e4SLinus Torvalds if (p1 == p2) { 28525955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28531da177e4SLinus Torvalds return NULL; 28541da177e4SLinus Torvalds } 28551da177e4SLinus Torvalds 2856fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 28571da177e4SLinus Torvalds 2858e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2859e2761a11SOGAWA Hirofumi if (p) { 28605955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 28615955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 28621da177e4SLinus Torvalds return p; 28631da177e4SLinus Torvalds } 28641da177e4SLinus Torvalds 2865e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2866e2761a11SOGAWA Hirofumi if (p) { 28675955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28685955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 28691da177e4SLinus Torvalds return p; 28701da177e4SLinus Torvalds } 28711da177e4SLinus Torvalds 28725955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28735955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 28741da177e4SLinus Torvalds return NULL; 28751da177e4SLinus Torvalds } 28764d359507SAl Viro EXPORT_SYMBOL(lock_rename); 28771da177e4SLinus Torvalds 28781da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 28791da177e4SLinus Torvalds { 28805955102cSAl Viro inode_unlock(p1->d_inode); 28811da177e4SLinus Torvalds if (p1 != p2) { 28825955102cSAl Viro inode_unlock(p2->d_inode); 2883fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 28841da177e4SLinus Torvalds } 28851da177e4SLinus Torvalds } 28864d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 28871da177e4SLinus Torvalds 28884acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2889312b63fbSAl Viro bool want_excl) 28901da177e4SLinus Torvalds { 2891a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28921da177e4SLinus Torvalds if (error) 28931da177e4SLinus Torvalds return error; 28941da177e4SLinus Torvalds 2895acfa4380SAl Viro if (!dir->i_op->create) 28961da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 28971da177e4SLinus Torvalds mode &= S_IALLUGO; 28981da177e4SLinus Torvalds mode |= S_IFREG; 28991da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 29001da177e4SLinus Torvalds if (error) 29011da177e4SLinus Torvalds return error; 2902312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2903a74574aaSStephen Smalley if (!error) 2904f38aa942SAmy Griffis fsnotify_create(dir, dentry); 29051da177e4SLinus Torvalds return error; 29061da177e4SLinus Torvalds } 29074d359507SAl Viro EXPORT_SYMBOL(vfs_create); 29081da177e4SLinus Torvalds 2909a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 2910a2982cc9SEric W. Biederman { 2911a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 2912a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 2913a2982cc9SEric W. Biederman } 2914a2982cc9SEric W. Biederman 2915f0bb5aafSAl Viro static int may_open(const struct path *path, int acc_mode, int flag) 29161da177e4SLinus Torvalds { 29173fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 29181da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 29191da177e4SLinus Torvalds int error; 29201da177e4SLinus Torvalds 29211da177e4SLinus Torvalds if (!inode) 29221da177e4SLinus Torvalds return -ENOENT; 29231da177e4SLinus Torvalds 2924c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2925c8fe8f30SChristoph Hellwig case S_IFLNK: 29261da177e4SLinus Torvalds return -ELOOP; 2927c8fe8f30SChristoph Hellwig case S_IFDIR: 2928c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 29291da177e4SLinus Torvalds return -EISDIR; 2930c8fe8f30SChristoph Hellwig break; 2931c8fe8f30SChristoph Hellwig case S_IFBLK: 2932c8fe8f30SChristoph Hellwig case S_IFCHR: 2933a2982cc9SEric W. Biederman if (!may_open_dev(path)) 29341da177e4SLinus Torvalds return -EACCES; 2935c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2936c8fe8f30SChristoph Hellwig case S_IFIFO: 2937c8fe8f30SChristoph Hellwig case S_IFSOCK: 29381da177e4SLinus Torvalds flag &= ~O_TRUNC; 2939c8fe8f30SChristoph Hellwig break; 29404a3fd211SDave Hansen } 2941b41572e9SDave Hansen 294262fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2943b41572e9SDave Hansen if (error) 2944b41572e9SDave Hansen return error; 29456146f0d5SMimi Zohar 29461da177e4SLinus Torvalds /* 29471da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 29481da177e4SLinus Torvalds */ 29491da177e4SLinus Torvalds if (IS_APPEND(inode)) { 29508737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 29517715b521SAl Viro return -EPERM; 29521da177e4SLinus Torvalds if (flag & O_TRUNC) 29537715b521SAl Viro return -EPERM; 29541da177e4SLinus Torvalds } 29551da177e4SLinus Torvalds 29561da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 29572e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 29587715b521SAl Viro return -EPERM; 29591da177e4SLinus Torvalds 2960f3c7691eSJ. Bruce Fields return 0; 29617715b521SAl Viro } 29627715b521SAl Viro 2963e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 29647715b521SAl Viro { 2965f0bb5aafSAl Viro const struct path *path = &filp->f_path; 29667715b521SAl Viro struct inode *inode = path->dentry->d_inode; 29677715b521SAl Viro int error = get_write_access(inode); 29681da177e4SLinus Torvalds if (error) 29697715b521SAl Viro return error; 29701da177e4SLinus Torvalds /* 29711da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 29721da177e4SLinus Torvalds */ 2973d7a06983SJeff Layton error = locks_verify_locked(filp); 2974be6d3e56SKentaro Takeda if (!error) 2975ea0d3ab2STetsuo Handa error = security_path_truncate(path); 29761da177e4SLinus Torvalds if (!error) { 29777715b521SAl Viro error = do_truncate(path->dentry, 0, 2978d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2979e1181ee6SJeff Layton filp); 29801da177e4SLinus Torvalds } 29811da177e4SLinus Torvalds put_write_access(inode); 2982acd0c935SMimi Zohar return error; 29831da177e4SLinus Torvalds } 29841da177e4SLinus Torvalds 2985d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2986d57999e1SDave Hansen { 29878a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 29888a5e929dSAl Viro flag--; 2989d57999e1SDave Hansen return flag; 2990d57999e1SDave Hansen } 2991d57999e1SDave Hansen 2992d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 2993d18e9008SMiklos Szeredi { 29941328c727SSeth Forshee struct user_namespace *s_user_ns; 2995d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2996d18e9008SMiklos Szeredi if (error) 2997d18e9008SMiklos Szeredi return error; 2998d18e9008SMiklos Szeredi 29991328c727SSeth Forshee s_user_ns = dir->dentry->d_sb->s_user_ns; 30001328c727SSeth Forshee if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 30011328c727SSeth Forshee !kgid_has_mapping(s_user_ns, current_fsgid())) 30021328c727SSeth Forshee return -EOVERFLOW; 30031328c727SSeth Forshee 3004d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 3005d18e9008SMiklos Szeredi if (error) 3006d18e9008SMiklos Szeredi return error; 3007d18e9008SMiklos Szeredi 3008d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 3009d18e9008SMiklos Szeredi } 3010d18e9008SMiklos Szeredi 30111acf0af9SDavid Howells /* 30121acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 30131acf0af9SDavid Howells * dentry. 30141acf0af9SDavid Howells * 30151acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 30161acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 30171acf0af9SDavid Howells * 30181acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 30191acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 30201acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 30211acf0af9SDavid Howells * 30221acf0af9SDavid Howells * Returns an error code otherwise. 30231acf0af9SDavid Howells */ 30242675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 302530d90494SAl Viro struct path *path, struct file *file, 3026015c3bbcSMiklos Szeredi const struct open_flags *op, 30271643b43fSAl Viro int open_flag, umode_t mode, 302847237687SAl Viro int *opened) 3029d18e9008SMiklos Szeredi { 3030d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 3031d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 3032d18e9008SMiklos Szeredi int error; 3033d18e9008SMiklos Szeredi 3034384f26e2SAl Viro if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ 3035d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 3036d18e9008SMiklos Szeredi 3037d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 3038d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 3039d18e9008SMiklos Szeredi 304030d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 304130d90494SAl Viro file->f_path.mnt = nd->path.mnt; 30420fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 30430fb1ea09SAl Viro open_to_namei_flags(open_flag), 30440fb1ea09SAl Viro mode, opened); 30456fbd0714SAl Viro d_lookup_done(dentry); 3046384f26e2SAl Viro if (!error) { 3047d18e9008SMiklos Szeredi /* 3048384f26e2SAl Viro * We didn't have the inode before the open, so check open 3049384f26e2SAl Viro * permission here. 3050d18e9008SMiklos Szeredi */ 3051384f26e2SAl Viro int acc_mode = op->acc_mode; 305203da633aSAl Viro if (*opened & FILE_CREATED) { 305303da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 305403da633aSAl Viro fsnotify_create(dir, dentry); 305562fb4a15SAl Viro acc_mode = 0; 305603da633aSAl Viro } 30572675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 3058384f26e2SAl Viro if (WARN_ON(error > 0)) 3059384f26e2SAl Viro error = -EINVAL; 3060384f26e2SAl Viro } else if (error > 0) { 3061d18e9008SMiklos Szeredi if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 3062d18e9008SMiklos Szeredi error = -EIO; 3063384f26e2SAl Viro } else { 3064d18e9008SMiklos Szeredi if (file->f_path.dentry) { 3065d18e9008SMiklos Szeredi dput(dentry); 3066d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 306710c64ceaSAl Viro } 3068d18e9008SMiklos Szeredi if (*opened & FILE_CREATED) 3069d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 3070a01e718fSAl Viro if (unlikely(d_is_negative(dentry))) { 3071a01e718fSAl Viro error = -ENOENT; 3072a01e718fSAl Viro } else { 3073d18e9008SMiklos Szeredi path->dentry = dentry; 3074d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 30752675a4ebSAl Viro return 1; 3076d18e9008SMiklos Szeredi } 3077d18e9008SMiklos Szeredi } 3078a01e718fSAl Viro } 3079d18e9008SMiklos Szeredi dput(dentry); 3080d18e9008SMiklos Szeredi return error; 3081d18e9008SMiklos Szeredi } 3082d18e9008SMiklos Szeredi 308331e6b01fSNick Piggin /* 30841acf0af9SDavid Howells * Look up and maybe create and open the last component. 3085d58ffd35SMiklos Szeredi * 3086d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 3087d58ffd35SMiklos Szeredi * 30881acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 30891acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 30901acf0af9SDavid Howells * 30911acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 30921acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 30931acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 30941acf0af9SDavid Howells * specified then a negative dentry may be returned. 30951acf0af9SDavid Howells * 30961acf0af9SDavid Howells * An error code is returned otherwise. 30971acf0af9SDavid Howells * 30981acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 30991acf0af9SDavid Howells * cleared otherwise prior to returning. 3100d58ffd35SMiklos Szeredi */ 31012675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 310230d90494SAl Viro struct file *file, 3103d58ffd35SMiklos Szeredi const struct open_flags *op, 310464894cf8SAl Viro bool got_write, int *opened) 3105d58ffd35SMiklos Szeredi { 3106d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 310754ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 31081643b43fSAl Viro int open_flag = op->open_flag; 3109d58ffd35SMiklos Szeredi struct dentry *dentry; 31101643b43fSAl Viro int error, create_error = 0; 31111643b43fSAl Viro umode_t mode = op->mode; 31126fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3113d58ffd35SMiklos Szeredi 3114ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3115ce8644fcSAl Viro return -ENOENT; 3116d58ffd35SMiklos Szeredi 311747237687SAl Viro *opened &= ~FILE_CREATED; 31186fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 31196fbd0714SAl Viro for (;;) { 31206fbd0714SAl Viro if (!dentry) { 31216fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3122d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 31232675a4ebSAl Viro return PTR_ERR(dentry); 31246fbd0714SAl Viro } 31256fbd0714SAl Viro if (d_in_lookup(dentry)) 31266fbd0714SAl Viro break; 3127d58ffd35SMiklos Szeredi 31286fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 31296fbd0714SAl Viro if (likely(error > 0)) 31306fbd0714SAl Viro break; 31316fbd0714SAl Viro if (error) 31326fbd0714SAl Viro goto out_dput; 31336fbd0714SAl Viro d_invalidate(dentry); 31346fbd0714SAl Viro dput(dentry); 31356fbd0714SAl Viro dentry = NULL; 31366fbd0714SAl Viro } 31376fbd0714SAl Viro if (dentry->d_inode) { 3138d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3139d18e9008SMiklos Szeredi goto out_no_open; 31406c51e513SAl Viro } 3141d18e9008SMiklos Szeredi 31421643b43fSAl Viro /* 31431643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 31441643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 31451643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 31461643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 31471643b43fSAl Viro * 31481643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 31491643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 31501643b43fSAl Viro */ 31511643b43fSAl Viro if (open_flag & O_CREAT) { 31521643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 31531643b43fSAl Viro mode &= ~current_umask(); 31541643b43fSAl Viro if (unlikely(!got_write)) { 31551643b43fSAl Viro create_error = -EROFS; 31561643b43fSAl Viro open_flag &= ~O_CREAT; 31571643b43fSAl Viro if (open_flag & (O_EXCL | O_TRUNC)) 31581643b43fSAl Viro goto no_open; 31591643b43fSAl Viro /* No side effects, safe to clear O_CREAT */ 31601643b43fSAl Viro } else { 31611643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 31621643b43fSAl Viro if (create_error) { 31631643b43fSAl Viro open_flag &= ~O_CREAT; 31641643b43fSAl Viro if (open_flag & O_EXCL) 31651643b43fSAl Viro goto no_open; 31661643b43fSAl Viro } 31671643b43fSAl Viro } 31681643b43fSAl Viro } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && 31691643b43fSAl Viro unlikely(!got_write)) { 31701643b43fSAl Viro /* 31711643b43fSAl Viro * No O_CREATE -> atomicity not a requirement -> fall 31721643b43fSAl Viro * back to lookup + open 31731643b43fSAl Viro */ 31741643b43fSAl Viro goto no_open; 3175d18e9008SMiklos Szeredi } 3176d18e9008SMiklos Szeredi 31771643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 31781643b43fSAl Viro error = atomic_open(nd, dentry, path, file, op, open_flag, 31791643b43fSAl Viro mode, opened); 31801643b43fSAl Viro if (unlikely(error == -ENOENT) && create_error) 31811643b43fSAl Viro error = create_error; 31821643b43fSAl Viro return error; 31831643b43fSAl Viro } 318454ef4872SMiklos Szeredi 31851643b43fSAl Viro no_open: 31866fbd0714SAl Viro if (d_in_lookup(dentry)) { 318712fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 318812fa5e24SAl Viro nd->flags); 31896fbd0714SAl Viro d_lookup_done(dentry); 319012fa5e24SAl Viro if (unlikely(res)) { 319112fa5e24SAl Viro if (IS_ERR(res)) { 319212fa5e24SAl Viro error = PTR_ERR(res); 319312fa5e24SAl Viro goto out_dput; 319412fa5e24SAl Viro } 319512fa5e24SAl Viro dput(dentry); 319612fa5e24SAl Viro dentry = res; 319712fa5e24SAl Viro } 319854ef4872SMiklos Szeredi } 319954ef4872SMiklos Szeredi 3200d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 32011643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 320247237687SAl Viro *opened |= FILE_CREATED; 3203ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3204ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3205ce8644fcSAl Viro error = -EACCES; 3206d58ffd35SMiklos Szeredi goto out_dput; 320777d660a8SMiklos Szeredi } 3208ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 32091643b43fSAl Viro open_flag & O_EXCL); 3210d58ffd35SMiklos Szeredi if (error) 3211d58ffd35SMiklos Szeredi goto out_dput; 3212ce8644fcSAl Viro fsnotify_create(dir_inode, dentry); 3213d58ffd35SMiklos Szeredi } 32141643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 32151643b43fSAl Viro error = create_error; 3216d58ffd35SMiklos Szeredi goto out_dput; 3217d58ffd35SMiklos Szeredi } 3218d18e9008SMiklos Szeredi out_no_open: 3219d58ffd35SMiklos Szeredi path->dentry = dentry; 3220d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 32212675a4ebSAl Viro return 1; 3222d58ffd35SMiklos Szeredi 3223d58ffd35SMiklos Szeredi out_dput: 3224d58ffd35SMiklos Szeredi dput(dentry); 32252675a4ebSAl Viro return error; 3226d58ffd35SMiklos Szeredi } 3227d58ffd35SMiklos Szeredi 3228d58ffd35SMiklos Szeredi /* 3229fe2d35ffSAl Viro * Handle the last step of open() 323031e6b01fSNick Piggin */ 3231896475d5SAl Viro static int do_last(struct nameidata *nd, 323230d90494SAl Viro struct file *file, const struct open_flags *op, 323376ae2a5aSAl Viro int *opened) 3234fb1cc555SAl Viro { 3235a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3236ca344a89SAl Viro int open_flag = op->open_flag; 323777d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 323864894cf8SAl Viro bool got_write = false; 3239bcda7652SAl Viro int acc_mode = op->acc_mode; 3240254cf582SAl Viro unsigned seq; 3241a1eb3315SMiklos Szeredi struct inode *inode; 3242896475d5SAl Viro struct path path; 324316c2cd71SAl Viro int error; 3244fb1cc555SAl Viro 3245c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3246c3e380b0SAl Viro nd->flags |= op->intent; 3247c3e380b0SAl Viro 3248bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3249fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3250deb106c6SAl Viro if (unlikely(error)) 32512675a4ebSAl Viro return error; 3252e83db167SMiklos Szeredi goto finish_open; 32531f36f774SAl Viro } 3254a2c36b45SAl Viro 3255ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3256fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3257fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3258fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3259254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 3260e9742b53SAl Viro if (likely(error > 0)) 326171574865SMiklos Szeredi goto finish_lookup; 326271574865SMiklos Szeredi 3263ce57dfc1SAl Viro if (error < 0) 3264deb106c6SAl Viro return error; 3265a1eb3315SMiklos Szeredi 326637d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 32676583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3268b6183df7SMiklos Szeredi } else { 3269fe2d35ffSAl Viro /* create side of things */ 3270a3fbbde7SAl Viro /* 3271b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3272b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3273b6183df7SMiklos Szeredi * about to look up 3274a3fbbde7SAl Viro */ 32759f1fafeeSAl Viro error = complete_walk(nd); 3276e8bb73dfSAl Viro if (error) 32772675a4ebSAl Viro return error; 3278fe2d35ffSAl Viro 327976ae2a5aSAl Viro audit_inode(nd->name, dir, LOOKUP_PARENT); 32801f36f774SAl Viro /* trailing slashes? */ 3281deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3282deb106c6SAl Viro return -EISDIR; 3283b6183df7SMiklos Szeredi } 32841f36f774SAl Viro 32859cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 328664894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 328764894cf8SAl Viro if (!error) 328864894cf8SAl Viro got_write = true; 328964894cf8SAl Viro /* 329064894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 329164894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 329264894cf8SAl Viro * dropping this one anyway. 329364894cf8SAl Viro */ 329464894cf8SAl Viro } 32959cf843e3SAl Viro if (open_flag & O_CREAT) 32965955102cSAl Viro inode_lock(dir->d_inode); 32979cf843e3SAl Viro else 32989cf843e3SAl Viro inode_lock_shared(dir->d_inode); 3299896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 33009cf843e3SAl Viro if (open_flag & O_CREAT) 33015955102cSAl Viro inode_unlock(dir->d_inode); 33029cf843e3SAl Viro else 33039cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3304fb1cc555SAl Viro 33052675a4ebSAl Viro if (error <= 0) { 33062675a4ebSAl Viro if (error) 3307d58ffd35SMiklos Szeredi goto out; 33086c0d46c4SAl Viro 330947237687SAl Viro if ((*opened & FILE_CREATED) || 3310496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 331177d660a8SMiklos Szeredi will_truncate = false; 3312d18e9008SMiklos Szeredi 331376ae2a5aSAl Viro audit_inode(nd->name, file->f_path.dentry, 0); 3314d18e9008SMiklos Szeredi goto opened; 3315d18e9008SMiklos Szeredi } 3316d18e9008SMiklos Szeredi 331747237687SAl Viro if (*opened & FILE_CREATED) { 33189b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3319ca344a89SAl Viro open_flag &= ~O_TRUNC; 332077d660a8SMiklos Szeredi will_truncate = false; 332162fb4a15SAl Viro acc_mode = 0; 3322896475d5SAl Viro path_to_nameidata(&path, nd); 3323e83db167SMiklos Szeredi goto finish_open_created; 3324fb1cc555SAl Viro } 3325fb1cc555SAl Viro 3326fb1cc555SAl Viro /* 3327d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3328d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3329d18e9008SMiklos Szeredi * necessary...) 3330d18e9008SMiklos Szeredi */ 333164894cf8SAl Viro if (got_write) { 3332d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 333364894cf8SAl Viro got_write = false; 3334d18e9008SMiklos Szeredi } 3335d18e9008SMiklos Szeredi 3336e6ec03a2SAl Viro error = follow_managed(&path, nd); 3337e6ec03a2SAl Viro if (unlikely(error < 0)) 3338e6ec03a2SAl Viro return error; 3339e6ec03a2SAl Viro 33406583fe22SAl Viro if (unlikely(d_is_negative(path.dentry))) { 33416583fe22SAl Viro path_to_nameidata(&path, nd); 33426583fe22SAl Viro return -ENOENT; 33436583fe22SAl Viro } 33446583fe22SAl Viro 33456583fe22SAl Viro /* 33466583fe22SAl Viro * create/update audit record if it already exists. 33476583fe22SAl Viro */ 33486583fe22SAl Viro audit_inode(nd->name, path.dentry, 0); 33496583fe22SAl Viro 3350deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3351deb106c6SAl Viro path_to_nameidata(&path, nd); 3352deb106c6SAl Viro return -EEXIST; 3353deb106c6SAl Viro } 3354fb1cc555SAl Viro 3355254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3356d4565649SAl Viro inode = d_backing_inode(path.dentry); 3357766c4cbfSAl Viro finish_lookup: 33588f64fb1cSAl Viro error = step_into(nd, &path, 0, inode, seq); 3359deb106c6SAl Viro if (unlikely(error)) 3360d63ff28fSAl Viro return error; 3361bc77daa7SAl Viro finish_open: 33628f64fb1cSAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3363a3fbbde7SAl Viro error = complete_walk(nd); 3364fac7d191SAl Viro if (error) 33652675a4ebSAl Viro return error; 336676ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 3367fb1cc555SAl Viro error = -EISDIR; 336844b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 33692675a4ebSAl Viro goto out; 3370af2f5542SMiklos Szeredi error = -ENOTDIR; 337144b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 33722675a4ebSAl Viro goto out; 33734bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 337477d660a8SMiklos Szeredi will_truncate = false; 33756c0d46c4SAl Viro 33760f9d1a10SAl Viro if (will_truncate) { 33770f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 33780f9d1a10SAl Viro if (error) 33792675a4ebSAl Viro goto out; 338064894cf8SAl Viro got_write = true; 33810f9d1a10SAl Viro } 3382e83db167SMiklos Szeredi finish_open_created: 3383bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3384ca344a89SAl Viro if (error) 33852675a4ebSAl Viro goto out; 33864aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 33874aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 3388fac7d191SAl Viro if (error) 3389015c3bbcSMiklos Szeredi goto out; 3390fac7d191SAl Viro *opened |= FILE_OPENED; 3391a8277b9bSMiklos Szeredi opened: 33922675a4ebSAl Viro error = open_check_o_direct(file); 3393fe9ec829SAl Viro if (!error) 33943034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3395fe9ec829SAl Viro if (!error && will_truncate) 33962675a4ebSAl Viro error = handle_truncate(file); 3397ca344a89SAl Viro out: 3398fe9ec829SAl Viro if (unlikely(error) && (*opened & FILE_OPENED)) 3399fe9ec829SAl Viro fput(file); 3400c80567c8SAl Viro if (unlikely(error > 0)) { 3401c80567c8SAl Viro WARN_ON(1); 3402c80567c8SAl Viro error = -EINVAL; 3403c80567c8SAl Viro } 340464894cf8SAl Viro if (got_write) 34050f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 34062675a4ebSAl Viro return error; 3407fb1cc555SAl Viro } 3408fb1cc555SAl Viro 3409af7bd4dcSAmir Goldstein struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode, int open_flag) 3410af7bd4dcSAmir Goldstein { 3411af7bd4dcSAmir Goldstein struct dentry *child = NULL; 3412af7bd4dcSAmir Goldstein struct inode *dir = dentry->d_inode; 3413af7bd4dcSAmir Goldstein struct inode *inode; 3414af7bd4dcSAmir Goldstein int error; 3415af7bd4dcSAmir Goldstein 3416af7bd4dcSAmir Goldstein /* we want directory to be writable */ 3417af7bd4dcSAmir Goldstein error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 3418af7bd4dcSAmir Goldstein if (error) 3419af7bd4dcSAmir Goldstein goto out_err; 3420af7bd4dcSAmir Goldstein error = -EOPNOTSUPP; 3421af7bd4dcSAmir Goldstein if (!dir->i_op->tmpfile) 3422af7bd4dcSAmir Goldstein goto out_err; 3423af7bd4dcSAmir Goldstein error = -ENOMEM; 3424cdf01226SDavid Howells child = d_alloc(dentry, &slash_name); 3425af7bd4dcSAmir Goldstein if (unlikely(!child)) 3426af7bd4dcSAmir Goldstein goto out_err; 3427af7bd4dcSAmir Goldstein error = dir->i_op->tmpfile(dir, child, mode); 3428af7bd4dcSAmir Goldstein if (error) 3429af7bd4dcSAmir Goldstein goto out_err; 3430af7bd4dcSAmir Goldstein error = -ENOENT; 3431af7bd4dcSAmir Goldstein inode = child->d_inode; 3432af7bd4dcSAmir Goldstein if (unlikely(!inode)) 3433af7bd4dcSAmir Goldstein goto out_err; 3434af7bd4dcSAmir Goldstein if (!(open_flag & O_EXCL)) { 3435af7bd4dcSAmir Goldstein spin_lock(&inode->i_lock); 3436af7bd4dcSAmir Goldstein inode->i_state |= I_LINKABLE; 3437af7bd4dcSAmir Goldstein spin_unlock(&inode->i_lock); 3438af7bd4dcSAmir Goldstein } 3439af7bd4dcSAmir Goldstein return child; 3440af7bd4dcSAmir Goldstein 3441af7bd4dcSAmir Goldstein out_err: 3442af7bd4dcSAmir Goldstein dput(child); 3443af7bd4dcSAmir Goldstein return ERR_PTR(error); 3444af7bd4dcSAmir Goldstein } 3445af7bd4dcSAmir Goldstein EXPORT_SYMBOL(vfs_tmpfile); 3446af7bd4dcSAmir Goldstein 3447c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 344860545d0dSAl Viro const struct open_flags *op, 344960545d0dSAl Viro struct file *file, int *opened) 345060545d0dSAl Viro { 3451625b6d10SAl Viro struct dentry *child; 3452625b6d10SAl Viro struct path path; 3453c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 345460545d0dSAl Viro if (unlikely(error)) 345560545d0dSAl Viro return error; 3456625b6d10SAl Viro error = mnt_want_write(path.mnt); 345760545d0dSAl Viro if (unlikely(error)) 345860545d0dSAl Viro goto out; 3459af7bd4dcSAmir Goldstein child = vfs_tmpfile(path.dentry, op->mode, op->open_flag); 3460af7bd4dcSAmir Goldstein error = PTR_ERR(child); 3461af7bd4dcSAmir Goldstein if (unlikely(IS_ERR(child))) 346260545d0dSAl Viro goto out2; 3463625b6d10SAl Viro dput(path.dentry); 3464625b6d10SAl Viro path.dentry = child; 3465c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 346669a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 346762fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 346860545d0dSAl Viro if (error) 346960545d0dSAl Viro goto out2; 3470625b6d10SAl Viro file->f_path.mnt = path.mnt; 3471625b6d10SAl Viro error = finish_open(file, child, NULL, opened); 347260545d0dSAl Viro if (error) 347360545d0dSAl Viro goto out2; 347460545d0dSAl Viro error = open_check_o_direct(file); 3475af7bd4dcSAmir Goldstein if (error) 347660545d0dSAl Viro fput(file); 347760545d0dSAl Viro out2: 3478625b6d10SAl Viro mnt_drop_write(path.mnt); 347960545d0dSAl Viro out: 3480625b6d10SAl Viro path_put(&path); 348160545d0dSAl Viro return error; 348260545d0dSAl Viro } 348360545d0dSAl Viro 34846ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 34856ac08709SAl Viro { 34866ac08709SAl Viro struct path path; 34876ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 34886ac08709SAl Viro if (!error) { 34896ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 34906ac08709SAl Viro error = vfs_open(&path, file, current_cred()); 34916ac08709SAl Viro path_put(&path); 34926ac08709SAl Viro } 34936ac08709SAl Viro return error; 34946ac08709SAl Viro } 34956ac08709SAl Viro 3496c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3497c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 34981da177e4SLinus Torvalds { 3499368ee9baSAl Viro const char *s; 350030d90494SAl Viro struct file *file; 350147237687SAl Viro int opened = 0; 350213aab428SAl Viro int error; 350331e6b01fSNick Piggin 350430d90494SAl Viro file = get_empty_filp(); 35051afc99beSAl Viro if (IS_ERR(file)) 35061afc99beSAl Viro return file; 350731e6b01fSNick Piggin 350830d90494SAl Viro file->f_flags = op->open_flag; 350931e6b01fSNick Piggin 3510bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 3511c8a53ee5SAl Viro error = do_tmpfile(nd, flags, op, file, &opened); 3512f15133dfSAl Viro goto out2; 351360545d0dSAl Viro } 351460545d0dSAl Viro 35156ac08709SAl Viro if (unlikely(file->f_flags & O_PATH)) { 35166ac08709SAl Viro error = do_o_path(nd, flags, file); 35176ac08709SAl Viro if (!error) 35186ac08709SAl Viro opened |= FILE_OPENED; 35196ac08709SAl Viro goto out2; 35206ac08709SAl Viro } 35216ac08709SAl Viro 3522c8a53ee5SAl Viro s = path_init(nd, flags); 3523368ee9baSAl Viro if (IS_ERR(s)) { 3524368ee9baSAl Viro put_filp(file); 3525368ee9baSAl Viro return ERR_CAST(s); 3526368ee9baSAl Viro } 35273bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 352876ae2a5aSAl Viro (error = do_last(nd, file, op, &opened)) > 0) { 352973d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 35303bdba28bSAl Viro s = trailing_symlink(nd); 35313bdba28bSAl Viro if (IS_ERR(s)) { 35323bdba28bSAl Viro error = PTR_ERR(s); 35332675a4ebSAl Viro break; 3534806b681cSAl Viro } 35353bdba28bSAl Viro } 3536deb106c6SAl Viro terminate_walk(nd); 3537f15133dfSAl Viro out2: 35382675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 35392675a4ebSAl Viro BUG_ON(!error); 354030d90494SAl Viro put_filp(file); 3541015c3bbcSMiklos Szeredi } 35422675a4ebSAl Viro if (unlikely(error)) { 35432675a4ebSAl Viro if (error == -EOPENSTALE) { 35442675a4ebSAl Viro if (flags & LOOKUP_RCU) 35452675a4ebSAl Viro error = -ECHILD; 35462675a4ebSAl Viro else 35472675a4ebSAl Viro error = -ESTALE; 35482675a4ebSAl Viro } 35492675a4ebSAl Viro file = ERR_PTR(error); 35502675a4ebSAl Viro } 35512675a4ebSAl Viro return file; 3552de459215SKirill Korotaev } 35531da177e4SLinus Torvalds 3554669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3555f9652e10SAl Viro const struct open_flags *op) 355613aab428SAl Viro { 35579883d185SAl Viro struct nameidata nd; 3558f9652e10SAl Viro int flags = op->lookup_flags; 355913aab428SAl Viro struct file *filp; 356013aab428SAl Viro 35619883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3562c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 356313aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3564c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 356513aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3566c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 35679883d185SAl Viro restore_nameidata(); 356813aab428SAl Viro return filp; 356913aab428SAl Viro } 357013aab428SAl Viro 357173d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3572f9652e10SAl Viro const char *name, const struct open_flags *op) 357373d049a4SAl Viro { 35749883d185SAl Viro struct nameidata nd; 357573d049a4SAl Viro struct file *file; 357651689104SPaul Moore struct filename *filename; 3577f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 357873d049a4SAl Viro 357973d049a4SAl Viro nd.root.mnt = mnt; 358073d049a4SAl Viro nd.root.dentry = dentry; 358173d049a4SAl Viro 3582b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 358373d049a4SAl Viro return ERR_PTR(-ELOOP); 358473d049a4SAl Viro 358551689104SPaul Moore filename = getname_kernel(name); 3586a1c83681SViresh Kumar if (IS_ERR(filename)) 358751689104SPaul Moore return ERR_CAST(filename); 358851689104SPaul Moore 35899883d185SAl Viro set_nameidata(&nd, -1, filename); 3590c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 359173d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3592c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 359373d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3594c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 35959883d185SAl Viro restore_nameidata(); 359651689104SPaul Moore putname(filename); 359773d049a4SAl Viro return file; 359873d049a4SAl Viro } 359973d049a4SAl Viro 3600fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 36011ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 36021da177e4SLinus Torvalds { 3603c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3604391172c4SAl Viro struct qstr last; 3605391172c4SAl Viro int type; 3606c30dabfeSJan Kara int err2; 36071ac12b4bSJeff Layton int error; 36081ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 36091ac12b4bSJeff Layton 36101ac12b4bSJeff Layton /* 36111ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 36121ac12b4bSJeff Layton * other flags passed in are ignored! 36131ac12b4bSJeff Layton */ 36141ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 36151ac12b4bSJeff Layton 36165c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 36175c31b6ceSAl Viro if (IS_ERR(name)) 36185c31b6ceSAl Viro return ERR_CAST(name); 36191da177e4SLinus Torvalds 3620c663e5d8SChristoph Hellwig /* 3621c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3622c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3623c663e5d8SChristoph Hellwig */ 36245c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3625ed75e95dSAl Viro goto out; 3626c663e5d8SChristoph Hellwig 3627c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3628391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3629c663e5d8SChristoph Hellwig /* 3630c663e5d8SChristoph Hellwig * Do the final lookup. 3631c663e5d8SChristoph Hellwig */ 3632391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 36335955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3634391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 36351da177e4SLinus Torvalds if (IS_ERR(dentry)) 3636a8104a9fSAl Viro goto unlock; 3637c663e5d8SChristoph Hellwig 3638a8104a9fSAl Viro error = -EEXIST; 3639b18825a7SDavid Howells if (d_is_positive(dentry)) 3640a8104a9fSAl Viro goto fail; 3641b18825a7SDavid Howells 3642c663e5d8SChristoph Hellwig /* 3643c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3644c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3645c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3646c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3647c663e5d8SChristoph Hellwig */ 3648391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3649a8104a9fSAl Viro error = -ENOENT; 3650ed75e95dSAl Viro goto fail; 3651e9baf6e5SAl Viro } 3652c30dabfeSJan Kara if (unlikely(err2)) { 3653c30dabfeSJan Kara error = err2; 3654a8104a9fSAl Viro goto fail; 3655c30dabfeSJan Kara } 3656181c37b6SAl Viro putname(name); 3657e9baf6e5SAl Viro return dentry; 36581da177e4SLinus Torvalds fail: 3659a8104a9fSAl Viro dput(dentry); 3660a8104a9fSAl Viro dentry = ERR_PTR(error); 3661a8104a9fSAl Viro unlock: 36625955102cSAl Viro inode_unlock(path->dentry->d_inode); 3663c30dabfeSJan Kara if (!err2) 3664391172c4SAl Viro mnt_drop_write(path->mnt); 3665ed75e95dSAl Viro out: 3666391172c4SAl Viro path_put(path); 3667181c37b6SAl Viro putname(name); 3668ed75e95dSAl Viro return dentry; 3669dae6ad8fSAl Viro } 3670fa14a0b8SAl Viro 3671fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3672fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3673fa14a0b8SAl Viro { 3674181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3675181c37b6SAl Viro path, lookup_flags); 3676fa14a0b8SAl Viro } 3677dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3678dae6ad8fSAl Viro 3679921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3680921a1650SAl Viro { 3681921a1650SAl Viro dput(dentry); 36825955102cSAl Viro inode_unlock(path->dentry->d_inode); 3683a8104a9fSAl Viro mnt_drop_write(path->mnt); 3684921a1650SAl Viro path_put(path); 3685921a1650SAl Viro } 3686921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3687921a1650SAl Viro 3688520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 36891ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3690dae6ad8fSAl Viro { 3691181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3692dae6ad8fSAl Viro } 3693dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3694dae6ad8fSAl Viro 36951a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 36961da177e4SLinus Torvalds { 3697a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36981da177e4SLinus Torvalds 36991da177e4SLinus Torvalds if (error) 37001da177e4SLinus Torvalds return error; 37011da177e4SLinus Torvalds 3702975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 37031da177e4SLinus Torvalds return -EPERM; 37041da177e4SLinus Torvalds 3705acfa4380SAl Viro if (!dir->i_op->mknod) 37061da177e4SLinus Torvalds return -EPERM; 37071da177e4SLinus Torvalds 370808ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 370908ce5f16SSerge E. Hallyn if (error) 371008ce5f16SSerge E. Hallyn return error; 371108ce5f16SSerge E. Hallyn 37121da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 37131da177e4SLinus Torvalds if (error) 37141da177e4SLinus Torvalds return error; 37151da177e4SLinus Torvalds 37161da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3717a74574aaSStephen Smalley if (!error) 3718f38aa942SAmy Griffis fsnotify_create(dir, dentry); 37191da177e4SLinus Torvalds return error; 37201da177e4SLinus Torvalds } 37214d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 37221da177e4SLinus Torvalds 3723f69aac00SAl Viro static int may_mknod(umode_t mode) 3724463c3197SDave Hansen { 3725463c3197SDave Hansen switch (mode & S_IFMT) { 3726463c3197SDave Hansen case S_IFREG: 3727463c3197SDave Hansen case S_IFCHR: 3728463c3197SDave Hansen case S_IFBLK: 3729463c3197SDave Hansen case S_IFIFO: 3730463c3197SDave Hansen case S_IFSOCK: 3731463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3732463c3197SDave Hansen return 0; 3733463c3197SDave Hansen case S_IFDIR: 3734463c3197SDave Hansen return -EPERM; 3735463c3197SDave Hansen default: 3736463c3197SDave Hansen return -EINVAL; 3737463c3197SDave Hansen } 3738463c3197SDave Hansen } 3739463c3197SDave Hansen 37408208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 37412e4d0924SHeiko Carstens unsigned, dev) 37421da177e4SLinus Torvalds { 37431da177e4SLinus Torvalds struct dentry *dentry; 3744dae6ad8fSAl Viro struct path path; 3745dae6ad8fSAl Viro int error; 3746972567f1SJeff Layton unsigned int lookup_flags = 0; 37471da177e4SLinus Torvalds 37488e4bfca1SAl Viro error = may_mknod(mode); 37498e4bfca1SAl Viro if (error) 37508e4bfca1SAl Viro return error; 3751972567f1SJeff Layton retry: 3752972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3753dae6ad8fSAl Viro if (IS_ERR(dentry)) 3754dae6ad8fSAl Viro return PTR_ERR(dentry); 37552ad94ae6SAl Viro 3756dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3757ce3b0f8dSAl Viro mode &= ~current_umask(); 3758dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3759be6d3e56SKentaro Takeda if (error) 3760a8104a9fSAl Viro goto out; 37611da177e4SLinus Torvalds switch (mode & S_IFMT) { 37621da177e4SLinus Torvalds case 0: case S_IFREG: 3763312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 376405d1a717SMimi Zohar if (!error) 376505d1a717SMimi Zohar ima_post_path_mknod(dentry); 37661da177e4SLinus Torvalds break; 37671da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3768dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 37691da177e4SLinus Torvalds new_decode_dev(dev)); 37701da177e4SLinus Torvalds break; 37711da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3772dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 37731da177e4SLinus Torvalds break; 37741da177e4SLinus Torvalds } 3775a8104a9fSAl Viro out: 3776921a1650SAl Viro done_path_create(&path, dentry); 3777972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3778972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3779972567f1SJeff Layton goto retry; 3780972567f1SJeff Layton } 37811da177e4SLinus Torvalds return error; 37821da177e4SLinus Torvalds } 37831da177e4SLinus Torvalds 37848208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 37855590ff0dSUlrich Drepper { 37865590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 37875590ff0dSUlrich Drepper } 37885590ff0dSUlrich Drepper 378918bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 37901da177e4SLinus Torvalds { 3791a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 37928de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 37931da177e4SLinus Torvalds 37941da177e4SLinus Torvalds if (error) 37951da177e4SLinus Torvalds return error; 37961da177e4SLinus Torvalds 3797acfa4380SAl Viro if (!dir->i_op->mkdir) 37981da177e4SLinus Torvalds return -EPERM; 37991da177e4SLinus Torvalds 38001da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 38011da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 38021da177e4SLinus Torvalds if (error) 38031da177e4SLinus Torvalds return error; 38041da177e4SLinus Torvalds 38058de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 38068de52778SAl Viro return -EMLINK; 38078de52778SAl Viro 38081da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3809a74574aaSStephen Smalley if (!error) 3810f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 38111da177e4SLinus Torvalds return error; 38121da177e4SLinus Torvalds } 38134d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 38141da177e4SLinus Torvalds 3815a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 38161da177e4SLinus Torvalds { 38176902d925SDave Hansen struct dentry *dentry; 3818dae6ad8fSAl Viro struct path path; 3819dae6ad8fSAl Viro int error; 3820b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 38211da177e4SLinus Torvalds 3822b76d8b82SJeff Layton retry: 3823b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 38246902d925SDave Hansen if (IS_ERR(dentry)) 3825dae6ad8fSAl Viro return PTR_ERR(dentry); 38266902d925SDave Hansen 3827dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3828ce3b0f8dSAl Viro mode &= ~current_umask(); 3829dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3830a8104a9fSAl Viro if (!error) 3831dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3832921a1650SAl Viro done_path_create(&path, dentry); 3833b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3834b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3835b76d8b82SJeff Layton goto retry; 3836b76d8b82SJeff Layton } 38371da177e4SLinus Torvalds return error; 38381da177e4SLinus Torvalds } 38391da177e4SLinus Torvalds 3840a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 38415590ff0dSUlrich Drepper { 38425590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 38435590ff0dSUlrich Drepper } 38445590ff0dSUlrich Drepper 38451da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 38461da177e4SLinus Torvalds { 38471da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 38481da177e4SLinus Torvalds 38491da177e4SLinus Torvalds if (error) 38501da177e4SLinus Torvalds return error; 38511da177e4SLinus Torvalds 3852acfa4380SAl Viro if (!dir->i_op->rmdir) 38531da177e4SLinus Torvalds return -EPERM; 38541da177e4SLinus Torvalds 38551d2ef590SAl Viro dget(dentry); 38565955102cSAl Viro inode_lock(dentry->d_inode); 3857912dbc15SSage Weil 38581da177e4SLinus Torvalds error = -EBUSY; 38597af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3860912dbc15SSage Weil goto out; 3861912dbc15SSage Weil 38621da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3863912dbc15SSage Weil if (error) 3864912dbc15SSage Weil goto out; 3865912dbc15SSage Weil 38663cebde24SSage Weil shrink_dcache_parent(dentry); 38671da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3868912dbc15SSage Weil if (error) 3869912dbc15SSage Weil goto out; 3870912dbc15SSage Weil 38711da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3872d83c49f3SAl Viro dont_mount(dentry); 38738ed936b5SEric W. Biederman detach_mounts(dentry); 38741da177e4SLinus Torvalds 3875912dbc15SSage Weil out: 38765955102cSAl Viro inode_unlock(dentry->d_inode); 38771d2ef590SAl Viro dput(dentry); 3878912dbc15SSage Weil if (!error) 3879912dbc15SSage Weil d_delete(dentry); 38801da177e4SLinus Torvalds return error; 38811da177e4SLinus Torvalds } 38824d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 38831da177e4SLinus Torvalds 38845590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 38851da177e4SLinus Torvalds { 38861da177e4SLinus Torvalds int error = 0; 388791a27b2aSJeff Layton struct filename *name; 38881da177e4SLinus Torvalds struct dentry *dentry; 3889f5beed75SAl Viro struct path path; 3890f5beed75SAl Viro struct qstr last; 3891f5beed75SAl Viro int type; 3892c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3893c6ee9206SJeff Layton retry: 3894c1d4dd27SAl Viro name = filename_parentat(dfd, getname(pathname), lookup_flags, 3895c1d4dd27SAl Viro &path, &last, &type); 389691a27b2aSJeff Layton if (IS_ERR(name)) 389791a27b2aSJeff Layton return PTR_ERR(name); 38981da177e4SLinus Torvalds 3899f5beed75SAl Viro switch (type) { 39001da177e4SLinus Torvalds case LAST_DOTDOT: 39011da177e4SLinus Torvalds error = -ENOTEMPTY; 39021da177e4SLinus Torvalds goto exit1; 39031da177e4SLinus Torvalds case LAST_DOT: 39041da177e4SLinus Torvalds error = -EINVAL; 39051da177e4SLinus Torvalds goto exit1; 39061da177e4SLinus Torvalds case LAST_ROOT: 39071da177e4SLinus Torvalds error = -EBUSY; 39081da177e4SLinus Torvalds goto exit1; 39091da177e4SLinus Torvalds } 39100612d9fbSOGAWA Hirofumi 3911f5beed75SAl Viro error = mnt_want_write(path.mnt); 3912c30dabfeSJan Kara if (error) 3913c30dabfeSJan Kara goto exit1; 39140612d9fbSOGAWA Hirofumi 39155955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3916f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 39171da177e4SLinus Torvalds error = PTR_ERR(dentry); 39186902d925SDave Hansen if (IS_ERR(dentry)) 39196902d925SDave Hansen goto exit2; 3920e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3921e6bc45d6STheodore Ts'o error = -ENOENT; 3922e6bc45d6STheodore Ts'o goto exit3; 3923e6bc45d6STheodore Ts'o } 3924f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3925be6d3e56SKentaro Takeda if (error) 3926c30dabfeSJan Kara goto exit3; 3927f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 39280622753bSDave Hansen exit3: 39291da177e4SLinus Torvalds dput(dentry); 39306902d925SDave Hansen exit2: 39315955102cSAl Viro inode_unlock(path.dentry->d_inode); 3932f5beed75SAl Viro mnt_drop_write(path.mnt); 39331da177e4SLinus Torvalds exit1: 3934f5beed75SAl Viro path_put(&path); 39351da177e4SLinus Torvalds putname(name); 3936c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3937c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3938c6ee9206SJeff Layton goto retry; 3939c6ee9206SJeff Layton } 39401da177e4SLinus Torvalds return error; 39411da177e4SLinus Torvalds } 39421da177e4SLinus Torvalds 39433cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 39445590ff0dSUlrich Drepper { 39455590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 39465590ff0dSUlrich Drepper } 39475590ff0dSUlrich Drepper 3948b21996e3SJ. Bruce Fields /** 3949b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3950b21996e3SJ. Bruce Fields * @dir: parent directory 3951b21996e3SJ. Bruce Fields * @dentry: victim 3952b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3953b21996e3SJ. Bruce Fields * 3954b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3955b21996e3SJ. Bruce Fields * 3956b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3957b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3958b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3959b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3960b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3961b21996e3SJ. Bruce Fields * 3962b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3963b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3964b21996e3SJ. Bruce Fields * to be NFS exported. 3965b21996e3SJ. Bruce Fields */ 3966b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 39671da177e4SLinus Torvalds { 39689accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 39691da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 39701da177e4SLinus Torvalds 39711da177e4SLinus Torvalds if (error) 39721da177e4SLinus Torvalds return error; 39731da177e4SLinus Torvalds 3974acfa4380SAl Viro if (!dir->i_op->unlink) 39751da177e4SLinus Torvalds return -EPERM; 39761da177e4SLinus Torvalds 39775955102cSAl Viro inode_lock(target); 39788ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 39791da177e4SLinus Torvalds error = -EBUSY; 39801da177e4SLinus Torvalds else { 39811da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3982bec1052eSAl Viro if (!error) { 39835a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 39845a14696cSJ. Bruce Fields if (error) 3985b21996e3SJ. Bruce Fields goto out; 39861da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 39878ed936b5SEric W. Biederman if (!error) { 3988d83c49f3SAl Viro dont_mount(dentry); 39898ed936b5SEric W. Biederman detach_mounts(dentry); 39908ed936b5SEric W. Biederman } 3991bec1052eSAl Viro } 39921da177e4SLinus Torvalds } 3993b21996e3SJ. Bruce Fields out: 39945955102cSAl Viro inode_unlock(target); 39951da177e4SLinus Torvalds 39961da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 39971da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 39989accbb97SJ. Bruce Fields fsnotify_link_count(target); 39991da177e4SLinus Torvalds d_delete(dentry); 40001da177e4SLinus Torvalds } 40010eeca283SRobert Love 40021da177e4SLinus Torvalds return error; 40031da177e4SLinus Torvalds } 40044d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 40051da177e4SLinus Torvalds 40061da177e4SLinus Torvalds /* 40071da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 40081b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 40091da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 40101da177e4SLinus Torvalds * while waiting on the I/O. 40111da177e4SLinus Torvalds */ 4012da2f1362SChristoph Hellwig long do_unlinkat(int dfd, struct filename *name) 40131da177e4SLinus Torvalds { 40142ad94ae6SAl Viro int error; 40151da177e4SLinus Torvalds struct dentry *dentry; 4016f5beed75SAl Viro struct path path; 4017f5beed75SAl Viro struct qstr last; 4018f5beed75SAl Viro int type; 40191da177e4SLinus Torvalds struct inode *inode = NULL; 4020b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 40215d18f813SJeff Layton unsigned int lookup_flags = 0; 40225d18f813SJeff Layton retry: 4023da2f1362SChristoph Hellwig name = filename_parentat(dfd, name, lookup_flags, &path, &last, &type); 402491a27b2aSJeff Layton if (IS_ERR(name)) 402591a27b2aSJeff Layton return PTR_ERR(name); 40262ad94ae6SAl Viro 40271da177e4SLinus Torvalds error = -EISDIR; 4028f5beed75SAl Viro if (type != LAST_NORM) 40291da177e4SLinus Torvalds goto exit1; 40300612d9fbSOGAWA Hirofumi 4031f5beed75SAl Viro error = mnt_want_write(path.mnt); 4032c30dabfeSJan Kara if (error) 4033c30dabfeSJan Kara goto exit1; 4034b21996e3SJ. Bruce Fields retry_deleg: 40355955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 4036f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 40371da177e4SLinus Torvalds error = PTR_ERR(dentry); 40381da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 40391da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 4040f5beed75SAl Viro if (last.name[last.len]) 404150338b88STörök Edwin goto slashes; 40421da177e4SLinus Torvalds inode = dentry->d_inode; 4043b18825a7SDavid Howells if (d_is_negative(dentry)) 4044e6bc45d6STheodore Ts'o goto slashes; 40457de9c6eeSAl Viro ihold(inode); 4046f5beed75SAl Viro error = security_path_unlink(&path, dentry); 4047be6d3e56SKentaro Takeda if (error) 4048c30dabfeSJan Kara goto exit2; 4049f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 40501da177e4SLinus Torvalds exit2: 40511da177e4SLinus Torvalds dput(dentry); 40521da177e4SLinus Torvalds } 40535955102cSAl Viro inode_unlock(path.dentry->d_inode); 40541da177e4SLinus Torvalds if (inode) 40551da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 4056b21996e3SJ. Bruce Fields inode = NULL; 4057b21996e3SJ. Bruce Fields if (delegated_inode) { 40585a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4059b21996e3SJ. Bruce Fields if (!error) 4060b21996e3SJ. Bruce Fields goto retry_deleg; 4061b21996e3SJ. Bruce Fields } 4062f5beed75SAl Viro mnt_drop_write(path.mnt); 40631da177e4SLinus Torvalds exit1: 4064f5beed75SAl Viro path_put(&path); 40655d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 40665d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 40675d18f813SJeff Layton inode = NULL; 40685d18f813SJeff Layton goto retry; 40695d18f813SJeff Layton } 4070da2f1362SChristoph Hellwig putname(name); 40711da177e4SLinus Torvalds return error; 40721da177e4SLinus Torvalds 40731da177e4SLinus Torvalds slashes: 4074b18825a7SDavid Howells if (d_is_negative(dentry)) 4075b18825a7SDavid Howells error = -ENOENT; 407644b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 4077b18825a7SDavid Howells error = -EISDIR; 4078b18825a7SDavid Howells else 4079b18825a7SDavid Howells error = -ENOTDIR; 40801da177e4SLinus Torvalds goto exit2; 40811da177e4SLinus Torvalds } 40821da177e4SLinus Torvalds 40832e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 40845590ff0dSUlrich Drepper { 40855590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 40865590ff0dSUlrich Drepper return -EINVAL; 40875590ff0dSUlrich Drepper 40885590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 40895590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 40905590ff0dSUlrich Drepper 4091da2f1362SChristoph Hellwig return do_unlinkat(dfd, getname(pathname)); 40925590ff0dSUlrich Drepper } 40935590ff0dSUlrich Drepper 40943480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 40955590ff0dSUlrich Drepper { 4096da2f1362SChristoph Hellwig return do_unlinkat(AT_FDCWD, getname(pathname)); 40975590ff0dSUlrich Drepper } 40985590ff0dSUlrich Drepper 4099db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 41001da177e4SLinus Torvalds { 4101a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 41021da177e4SLinus Torvalds 41031da177e4SLinus Torvalds if (error) 41041da177e4SLinus Torvalds return error; 41051da177e4SLinus Torvalds 4106acfa4380SAl Viro if (!dir->i_op->symlink) 41071da177e4SLinus Torvalds return -EPERM; 41081da177e4SLinus Torvalds 41091da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 41101da177e4SLinus Torvalds if (error) 41111da177e4SLinus Torvalds return error; 41121da177e4SLinus Torvalds 41131da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 4114a74574aaSStephen Smalley if (!error) 4115f38aa942SAmy Griffis fsnotify_create(dir, dentry); 41161da177e4SLinus Torvalds return error; 41171da177e4SLinus Torvalds } 41184d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 41191da177e4SLinus Torvalds 41202e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 41212e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 41221da177e4SLinus Torvalds { 41232ad94ae6SAl Viro int error; 412491a27b2aSJeff Layton struct filename *from; 41256902d925SDave Hansen struct dentry *dentry; 4126dae6ad8fSAl Viro struct path path; 4127f46d3567SJeff Layton unsigned int lookup_flags = 0; 41281da177e4SLinus Torvalds 41291da177e4SLinus Torvalds from = getname(oldname); 41301da177e4SLinus Torvalds if (IS_ERR(from)) 41311da177e4SLinus Torvalds return PTR_ERR(from); 4132f46d3567SJeff Layton retry: 4133f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 41341da177e4SLinus Torvalds error = PTR_ERR(dentry); 41356902d925SDave Hansen if (IS_ERR(dentry)) 4136dae6ad8fSAl Viro goto out_putname; 41376902d925SDave Hansen 413891a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4139a8104a9fSAl Viro if (!error) 414091a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4141921a1650SAl Viro done_path_create(&path, dentry); 4142f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4143f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4144f46d3567SJeff Layton goto retry; 4145f46d3567SJeff Layton } 41466902d925SDave Hansen out_putname: 41471da177e4SLinus Torvalds putname(from); 41481da177e4SLinus Torvalds return error; 41491da177e4SLinus Torvalds } 41501da177e4SLinus Torvalds 41513480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 41525590ff0dSUlrich Drepper { 41535590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 41545590ff0dSUlrich Drepper } 41555590ff0dSUlrich Drepper 4156146a8595SJ. Bruce Fields /** 4157146a8595SJ. Bruce Fields * vfs_link - create a new link 4158146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4159146a8595SJ. Bruce Fields * @dir: new parent 4160146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4161146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4162146a8595SJ. Bruce Fields * 4163146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4164146a8595SJ. Bruce Fields * 4165146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4166146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4167146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4168146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4169146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4170146a8595SJ. Bruce Fields * 4171146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4172146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4173146a8595SJ. Bruce Fields * to be NFS exported. 4174146a8595SJ. Bruce Fields */ 4175146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 41761da177e4SLinus Torvalds { 41771da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 41788de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 41791da177e4SLinus Torvalds int error; 41801da177e4SLinus Torvalds 41811da177e4SLinus Torvalds if (!inode) 41821da177e4SLinus Torvalds return -ENOENT; 41831da177e4SLinus Torvalds 4184a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 41851da177e4SLinus Torvalds if (error) 41861da177e4SLinus Torvalds return error; 41871da177e4SLinus Torvalds 41881da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 41891da177e4SLinus Torvalds return -EXDEV; 41901da177e4SLinus Torvalds 41911da177e4SLinus Torvalds /* 41921da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 41931da177e4SLinus Torvalds */ 41941da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 41951da177e4SLinus Torvalds return -EPERM; 41960bd23d09SEric W. Biederman /* 41970bd23d09SEric W. Biederman * Updating the link count will likely cause i_uid and i_gid to 41980bd23d09SEric W. Biederman * be writen back improperly if their true value is unknown to 41990bd23d09SEric W. Biederman * the vfs. 42000bd23d09SEric W. Biederman */ 42010bd23d09SEric W. Biederman if (HAS_UNMAPPED_ID(inode)) 42020bd23d09SEric W. Biederman return -EPERM; 4203acfa4380SAl Viro if (!dir->i_op->link) 42041da177e4SLinus Torvalds return -EPERM; 42057e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 42061da177e4SLinus Torvalds return -EPERM; 42071da177e4SLinus Torvalds 42081da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 42091da177e4SLinus Torvalds if (error) 42101da177e4SLinus Torvalds return error; 42111da177e4SLinus Torvalds 42125955102cSAl Viro inode_lock(inode); 4213aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4214f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4215aae8a97dSAneesh Kumar K.V error = -ENOENT; 42168de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 42178de52778SAl Viro error = -EMLINK; 4218146a8595SJ. Bruce Fields else { 4219146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4220146a8595SJ. Bruce Fields if (!error) 42211da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4222146a8595SJ. Bruce Fields } 4223f4e0c30cSAl Viro 4224f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4225f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4226f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4227f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4228f4e0c30cSAl Viro } 42295955102cSAl Viro inode_unlock(inode); 4230e31e14ecSStephen Smalley if (!error) 42317e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 42321da177e4SLinus Torvalds return error; 42331da177e4SLinus Torvalds } 42344d359507SAl Viro EXPORT_SYMBOL(vfs_link); 42351da177e4SLinus Torvalds 42361da177e4SLinus Torvalds /* 42371da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 42381da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 42391da177e4SLinus Torvalds * newname. --KAB 42401da177e4SLinus Torvalds * 42411da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 42421da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 42431da177e4SLinus Torvalds * and other special files. --ADM 42441da177e4SLinus Torvalds */ 42452e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 42462e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 42471da177e4SLinus Torvalds { 42481da177e4SLinus Torvalds struct dentry *new_dentry; 4249dae6ad8fSAl Viro struct path old_path, new_path; 4250146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 425111a7b371SAneesh Kumar K.V int how = 0; 42521da177e4SLinus Torvalds int error; 42531da177e4SLinus Torvalds 425411a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4255c04030e1SUlrich Drepper return -EINVAL; 425611a7b371SAneesh Kumar K.V /* 4257f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4258f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4259f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 426011a7b371SAneesh Kumar K.V */ 4261f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4262f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4263f0cc6ffbSLinus Torvalds return -ENOENT; 426411a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4265f0cc6ffbSLinus Torvalds } 4266c04030e1SUlrich Drepper 426711a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 426811a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4269442e31caSJeff Layton retry: 427011a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 42711da177e4SLinus Torvalds if (error) 42722ad94ae6SAl Viro return error; 42732ad94ae6SAl Viro 4274442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4275442e31caSJeff Layton (how & LOOKUP_REVAL)); 42761da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 42776902d925SDave Hansen if (IS_ERR(new_dentry)) 4278dae6ad8fSAl Viro goto out; 4279dae6ad8fSAl Viro 4280dae6ad8fSAl Viro error = -EXDEV; 4281dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4282dae6ad8fSAl Viro goto out_dput; 4283800179c9SKees Cook error = may_linkat(&old_path); 4284800179c9SKees Cook if (unlikely(error)) 4285800179c9SKees Cook goto out_dput; 4286dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4287be6d3e56SKentaro Takeda if (error) 4288a8104a9fSAl Viro goto out_dput; 4289146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 429075c3f29dSDave Hansen out_dput: 4291921a1650SAl Viro done_path_create(&new_path, new_dentry); 4292146a8595SJ. Bruce Fields if (delegated_inode) { 4293146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4294d22e6338SOleg Drokin if (!error) { 4295d22e6338SOleg Drokin path_put(&old_path); 4296146a8595SJ. Bruce Fields goto retry; 4297146a8595SJ. Bruce Fields } 4298d22e6338SOleg Drokin } 4299442e31caSJeff Layton if (retry_estale(error, how)) { 4300d22e6338SOleg Drokin path_put(&old_path); 4301442e31caSJeff Layton how |= LOOKUP_REVAL; 4302442e31caSJeff Layton goto retry; 4303442e31caSJeff Layton } 43041da177e4SLinus Torvalds out: 43052d8f3038SAl Viro path_put(&old_path); 43061da177e4SLinus Torvalds 43071da177e4SLinus Torvalds return error; 43081da177e4SLinus Torvalds } 43091da177e4SLinus Torvalds 43103480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 43115590ff0dSUlrich Drepper { 4312c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 43135590ff0dSUlrich Drepper } 43145590ff0dSUlrich Drepper 4315bc27027aSMiklos Szeredi /** 4316bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4317bc27027aSMiklos Szeredi * @old_dir: parent of source 4318bc27027aSMiklos Szeredi * @old_dentry: source 4319bc27027aSMiklos Szeredi * @new_dir: parent of destination 4320bc27027aSMiklos Szeredi * @new_dentry: destination 4321bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4322520c8b16SMiklos Szeredi * @flags: rename flags 4323bc27027aSMiklos Szeredi * 4324bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4325bc27027aSMiklos Szeredi * 4326bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4327bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4328bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4329bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4330bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4331bc27027aSMiklos Szeredi * so. 4332bc27027aSMiklos Szeredi * 4333bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4334bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4335bc27027aSMiklos Szeredi * to be NFS exported. 4336bc27027aSMiklos Szeredi * 43371da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 43381da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 43391da177e4SLinus Torvalds * Problems: 43400117d427SMauro Carvalho Chehab * 4341d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 43421da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 43431da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4344a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 43451da177e4SLinus Torvalds * story. 43466cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 43476cedba89SJ. Bruce Fields * and source (if it is not a directory). 43481b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 43491da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 43501da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4351a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 43521da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 43531da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 43541da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4355a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 43561da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 43571da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 43581da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4359e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 43601b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 43611da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4362c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 43631da177e4SLinus Torvalds * locking]. 43641da177e4SLinus Torvalds */ 43651da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 43668e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4367520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 43681da177e4SLinus Torvalds { 43691da177e4SLinus Torvalds int error; 4370bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 4371bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4372bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4373da1ce067SMiklos Szeredi bool new_is_dir = false; 4374da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 437549d31c2fSAl Viro struct name_snapshot old_name; 43761da177e4SLinus Torvalds 43778d3e2936SMiklos Szeredi if (source == target) 43781da177e4SLinus Torvalds return 0; 43791da177e4SLinus Torvalds 43801da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 43811da177e4SLinus Torvalds if (error) 43821da177e4SLinus Torvalds return error; 43831da177e4SLinus Torvalds 4384da1ce067SMiklos Szeredi if (!target) { 4385a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4386da1ce067SMiklos Szeredi } else { 4387da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4388da1ce067SMiklos Szeredi 4389da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43901da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4391da1ce067SMiklos Szeredi else 4392da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4393da1ce067SMiklos Szeredi } 43941da177e4SLinus Torvalds if (error) 43951da177e4SLinus Torvalds return error; 43961da177e4SLinus Torvalds 43972773bf00SMiklos Szeredi if (!old_dir->i_op->rename) 43981da177e4SLinus Torvalds return -EPERM; 43991da177e4SLinus Torvalds 4400bc27027aSMiklos Szeredi /* 4401bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4402bc27027aSMiklos Szeredi * we'll need to flip '..'. 4403bc27027aSMiklos Szeredi */ 4404da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4405da1ce067SMiklos Szeredi if (is_dir) { 4406bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4407bc27027aSMiklos Szeredi if (error) 4408bc27027aSMiklos Szeredi return error; 4409bc27027aSMiklos Szeredi } 4410da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4411da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4412da1ce067SMiklos Szeredi if (error) 4413da1ce067SMiklos Szeredi return error; 4414da1ce067SMiklos Szeredi } 4415da1ce067SMiklos Szeredi } 44160eeca283SRobert Love 44170b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 44180b3974ebSMiklos Szeredi flags); 4419bc27027aSMiklos Szeredi if (error) 4420bc27027aSMiklos Szeredi return error; 4421bc27027aSMiklos Szeredi 442249d31c2fSAl Viro take_dentry_name_snapshot(&old_name, old_dentry); 4423bc27027aSMiklos Szeredi dget(new_dentry); 4424da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4425bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4426bc27027aSMiklos Szeredi else if (target) 44275955102cSAl Viro inode_lock(target); 4428bc27027aSMiklos Szeredi 4429bc27027aSMiklos Szeredi error = -EBUSY; 44307af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4431bc27027aSMiklos Szeredi goto out; 4432bc27027aSMiklos Szeredi 4433da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4434bc27027aSMiklos Szeredi error = -EMLINK; 4435da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4436bc27027aSMiklos Szeredi goto out; 4437da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4438da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4439da1ce067SMiklos Szeredi goto out; 4440da1ce067SMiklos Szeredi } 4441da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4442bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4443da1ce067SMiklos Szeredi if (!is_dir) { 4444bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4445bc27027aSMiklos Szeredi if (error) 4446bc27027aSMiklos Szeredi goto out; 4447da1ce067SMiklos Szeredi } 4448da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4449bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4450bc27027aSMiklos Szeredi if (error) 4451bc27027aSMiklos Szeredi goto out; 4452bc27027aSMiklos Szeredi } 4453520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4454520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4455bc27027aSMiklos Szeredi if (error) 4456bc27027aSMiklos Szeredi goto out; 4457bc27027aSMiklos Szeredi 4458da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 44591da177e4SLinus Torvalds if (is_dir) 4460bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4461bc27027aSMiklos Szeredi dont_mount(new_dentry); 44628ed936b5SEric W. Biederman detach_mounts(new_dentry); 4463bc27027aSMiklos Szeredi } 4464da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4465da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4466bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4467da1ce067SMiklos Szeredi else 4468da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4469da1ce067SMiklos Szeredi } 4470bc27027aSMiklos Szeredi out: 4471da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4472bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4473bc27027aSMiklos Szeredi else if (target) 44745955102cSAl Viro inode_unlock(target); 4475bc27027aSMiklos Szeredi dput(new_dentry); 4476da1ce067SMiklos Szeredi if (!error) { 447749d31c2fSAl Viro fsnotify_move(old_dir, new_dir, old_name.name, is_dir, 4478da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4479da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4480da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4481da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4482da1ce067SMiklos Szeredi } 4483da1ce067SMiklos Szeredi } 448449d31c2fSAl Viro release_dentry_name_snapshot(&old_name); 44850eeca283SRobert Love 44861da177e4SLinus Torvalds return error; 44871da177e4SLinus Torvalds } 44884d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 44891da177e4SLinus Torvalds 4490520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4491520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 44921da177e4SLinus Torvalds { 44931da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 44941da177e4SLinus Torvalds struct dentry *trap; 4495f5beed75SAl Viro struct path old_path, new_path; 4496f5beed75SAl Viro struct qstr old_last, new_last; 4497f5beed75SAl Viro int old_type, new_type; 44988e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 449991a27b2aSJeff Layton struct filename *from; 450091a27b2aSJeff Layton struct filename *to; 4501f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4502c6a94284SJeff Layton bool should_retry = false; 45032ad94ae6SAl Viro int error; 4504520c8b16SMiklos Szeredi 45050d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4506da1ce067SMiklos Szeredi return -EINVAL; 4507da1ce067SMiklos Szeredi 45080d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 45090d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4510520c8b16SMiklos Szeredi return -EINVAL; 4511520c8b16SMiklos Szeredi 45120d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 45130d7a8555SMiklos Szeredi return -EPERM; 45140d7a8555SMiklos Szeredi 4515f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4516f5beed75SAl Viro target_flags = 0; 4517f5beed75SAl Viro 4518c6a94284SJeff Layton retry: 4519c1d4dd27SAl Viro from = filename_parentat(olddfd, getname(oldname), lookup_flags, 4520c1d4dd27SAl Viro &old_path, &old_last, &old_type); 452191a27b2aSJeff Layton if (IS_ERR(from)) { 452291a27b2aSJeff Layton error = PTR_ERR(from); 45231da177e4SLinus Torvalds goto exit; 452491a27b2aSJeff Layton } 45251da177e4SLinus Torvalds 4526c1d4dd27SAl Viro to = filename_parentat(newdfd, getname(newname), lookup_flags, 4527c1d4dd27SAl Viro &new_path, &new_last, &new_type); 452891a27b2aSJeff Layton if (IS_ERR(to)) { 452991a27b2aSJeff Layton error = PTR_ERR(to); 45301da177e4SLinus Torvalds goto exit1; 453191a27b2aSJeff Layton } 45321da177e4SLinus Torvalds 45331da177e4SLinus Torvalds error = -EXDEV; 4534f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 45351da177e4SLinus Torvalds goto exit2; 45361da177e4SLinus Torvalds 45371da177e4SLinus Torvalds error = -EBUSY; 4538f5beed75SAl Viro if (old_type != LAST_NORM) 45391da177e4SLinus Torvalds goto exit2; 45401da177e4SLinus Torvalds 45410a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 45420a7c3937SMiklos Szeredi error = -EEXIST; 4543f5beed75SAl Viro if (new_type != LAST_NORM) 45441da177e4SLinus Torvalds goto exit2; 45451da177e4SLinus Torvalds 4546f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4547c30dabfeSJan Kara if (error) 4548c30dabfeSJan Kara goto exit2; 4549c30dabfeSJan Kara 45508e6d782cSJ. Bruce Fields retry_deleg: 4551f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 45521da177e4SLinus Torvalds 4553f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 45541da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 45551da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 45561da177e4SLinus Torvalds goto exit3; 45571da177e4SLinus Torvalds /* source must exist */ 45581da177e4SLinus Torvalds error = -ENOENT; 4559b18825a7SDavid Howells if (d_is_negative(old_dentry)) 45601da177e4SLinus Torvalds goto exit4; 4561f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 45621da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 45631da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 45641da177e4SLinus Torvalds goto exit4; 45650a7c3937SMiklos Szeredi error = -EEXIST; 45660a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 45670a7c3937SMiklos Szeredi goto exit5; 4568da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4569da1ce067SMiklos Szeredi error = -ENOENT; 4570da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4571da1ce067SMiklos Szeredi goto exit5; 4572da1ce067SMiklos Szeredi 4573da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4574da1ce067SMiklos Szeredi error = -ENOTDIR; 4575f5beed75SAl Viro if (new_last.name[new_last.len]) 4576da1ce067SMiklos Szeredi goto exit5; 4577da1ce067SMiklos Szeredi } 4578da1ce067SMiklos Szeredi } 45790a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 45800a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 45810a7c3937SMiklos Szeredi error = -ENOTDIR; 4582f5beed75SAl Viro if (old_last.name[old_last.len]) 45830a7c3937SMiklos Szeredi goto exit5; 4584f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 45850a7c3937SMiklos Szeredi goto exit5; 45860a7c3937SMiklos Szeredi } 45870a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 45880a7c3937SMiklos Szeredi error = -EINVAL; 45890a7c3937SMiklos Szeredi if (old_dentry == trap) 45900a7c3937SMiklos Szeredi goto exit5; 45911da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4592da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 45931da177e4SLinus Torvalds error = -ENOTEMPTY; 45941da177e4SLinus Torvalds if (new_dentry == trap) 45951da177e4SLinus Torvalds goto exit5; 45961da177e4SLinus Torvalds 4597f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4598f5beed75SAl Viro &new_path, new_dentry, flags); 4599be6d3e56SKentaro Takeda if (error) 4600c30dabfeSJan Kara goto exit5; 4601f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4602f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4603520c8b16SMiklos Szeredi &delegated_inode, flags); 46041da177e4SLinus Torvalds exit5: 46051da177e4SLinus Torvalds dput(new_dentry); 46061da177e4SLinus Torvalds exit4: 46071da177e4SLinus Torvalds dput(old_dentry); 46081da177e4SLinus Torvalds exit3: 4609f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 46108e6d782cSJ. Bruce Fields if (delegated_inode) { 46118e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 46128e6d782cSJ. Bruce Fields if (!error) 46138e6d782cSJ. Bruce Fields goto retry_deleg; 46148e6d782cSJ. Bruce Fields } 4615f5beed75SAl Viro mnt_drop_write(old_path.mnt); 46161da177e4SLinus Torvalds exit2: 4617c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4618c6a94284SJeff Layton should_retry = true; 4619f5beed75SAl Viro path_put(&new_path); 46202ad94ae6SAl Viro putname(to); 46211da177e4SLinus Torvalds exit1: 4622f5beed75SAl Viro path_put(&old_path); 46231da177e4SLinus Torvalds putname(from); 4624c6a94284SJeff Layton if (should_retry) { 4625c6a94284SJeff Layton should_retry = false; 4626c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4627c6a94284SJeff Layton goto retry; 4628c6a94284SJeff Layton } 46292ad94ae6SAl Viro exit: 46301da177e4SLinus Torvalds return error; 46311da177e4SLinus Torvalds } 46321da177e4SLinus Torvalds 4633520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4634520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4635520c8b16SMiklos Szeredi { 4636520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4637520c8b16SMiklos Szeredi } 4638520c8b16SMiklos Szeredi 4639a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 46405590ff0dSUlrich Drepper { 4641520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 46425590ff0dSUlrich Drepper } 46435590ff0dSUlrich Drepper 4644787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4645787fb6bcSMiklos Szeredi { 4646787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4647787fb6bcSMiklos Szeredi if (error) 4648787fb6bcSMiklos Szeredi return error; 4649787fb6bcSMiklos Szeredi 4650787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4651787fb6bcSMiklos Szeredi return -EPERM; 4652787fb6bcSMiklos Szeredi 4653787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4654787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4655787fb6bcSMiklos Szeredi } 4656787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4657787fb6bcSMiklos Szeredi 46585d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 46591da177e4SLinus Torvalds { 46605d826c84SAl Viro int len = PTR_ERR(link); 46611da177e4SLinus Torvalds if (IS_ERR(link)) 46621da177e4SLinus Torvalds goto out; 46631da177e4SLinus Torvalds 46641da177e4SLinus Torvalds len = strlen(link); 46651da177e4SLinus Torvalds if (len > (unsigned) buflen) 46661da177e4SLinus Torvalds len = buflen; 46671da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 46681da177e4SLinus Torvalds len = -EFAULT; 46691da177e4SLinus Torvalds out: 46701da177e4SLinus Torvalds return len; 46711da177e4SLinus Torvalds } 46721da177e4SLinus Torvalds 46731da177e4SLinus Torvalds /* 46741da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 46756b255391SAl Viro * have ->get_link() not calling nd_jump_link(). Using (or not using) it 46766b255391SAl Viro * for any given inode is up to filesystem. 46771da177e4SLinus Torvalds */ 4678d16744ecSMiklos Szeredi static int generic_readlink(struct dentry *dentry, char __user *buffer, 4679d16744ecSMiklos Szeredi int buflen) 46801da177e4SLinus Torvalds { 4681fceef393SAl Viro DEFINE_DELAYED_CALL(done); 46825f2c4179SAl Viro struct inode *inode = d_inode(dentry); 46835f2c4179SAl Viro const char *link = inode->i_link; 4684694a1764SMarcin Slusarz int res; 4685cc314eefSLinus Torvalds 4686d4dee48bSAl Viro if (!link) { 4687fceef393SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4688680baacbSAl Viro if (IS_ERR(link)) 4689680baacbSAl Viro return PTR_ERR(link); 4690d4dee48bSAl Viro } 4691680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 4692fceef393SAl Viro do_delayed_call(&done); 4693694a1764SMarcin Slusarz return res; 46941da177e4SLinus Torvalds } 46951da177e4SLinus Torvalds 4696d60874cdSMiklos Szeredi /** 4697fd4a0edfSMiklos Szeredi * vfs_readlink - copy symlink body into userspace buffer 4698fd4a0edfSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4699fd4a0edfSMiklos Szeredi * @buffer: user memory pointer 4700fd4a0edfSMiklos Szeredi * @buflen: size of buffer 4701fd4a0edfSMiklos Szeredi * 4702fd4a0edfSMiklos Szeredi * Does not touch atime. That's up to the caller if necessary 4703fd4a0edfSMiklos Szeredi * 4704fd4a0edfSMiklos Szeredi * Does not call security hook. 4705fd4a0edfSMiklos Szeredi */ 4706fd4a0edfSMiklos Szeredi int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4707fd4a0edfSMiklos Szeredi { 4708fd4a0edfSMiklos Szeredi struct inode *inode = d_inode(dentry); 4709fd4a0edfSMiklos Szeredi 471076fca90eSMiklos Szeredi if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) { 471176fca90eSMiklos Szeredi if (unlikely(inode->i_op->readlink)) 471276fca90eSMiklos Szeredi return inode->i_op->readlink(dentry, buffer, buflen); 471376fca90eSMiklos Szeredi 471476fca90eSMiklos Szeredi if (!d_is_symlink(dentry)) 4715fd4a0edfSMiklos Szeredi return -EINVAL; 4716fd4a0edfSMiklos Szeredi 471776fca90eSMiklos Szeredi spin_lock(&inode->i_lock); 471876fca90eSMiklos Szeredi inode->i_opflags |= IOP_DEFAULT_READLINK; 471976fca90eSMiklos Szeredi spin_unlock(&inode->i_lock); 472076fca90eSMiklos Szeredi } 472176fca90eSMiklos Szeredi 472276fca90eSMiklos Szeredi return generic_readlink(dentry, buffer, buflen); 4723fd4a0edfSMiklos Szeredi } 4724fd4a0edfSMiklos Szeredi EXPORT_SYMBOL(vfs_readlink); 47251da177e4SLinus Torvalds 4726d60874cdSMiklos Szeredi /** 4727d60874cdSMiklos Szeredi * vfs_get_link - get symlink body 4728d60874cdSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4729d60874cdSMiklos Szeredi * @done: caller needs to free returned data with this 4730d60874cdSMiklos Szeredi * 4731d60874cdSMiklos Szeredi * Calls security hook and i_op->get_link() on the supplied inode. 4732d60874cdSMiklos Szeredi * 4733d60874cdSMiklos Szeredi * It does not touch atime. That's up to the caller if necessary. 4734d60874cdSMiklos Szeredi * 4735d60874cdSMiklos Szeredi * Does not work on "special" symlinks like /proc/$$/fd/N 4736d60874cdSMiklos Szeredi */ 4737d60874cdSMiklos Szeredi const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done) 4738d60874cdSMiklos Szeredi { 4739d60874cdSMiklos Szeredi const char *res = ERR_PTR(-EINVAL); 4740d60874cdSMiklos Szeredi struct inode *inode = d_inode(dentry); 4741d60874cdSMiklos Szeredi 4742d60874cdSMiklos Szeredi if (d_is_symlink(dentry)) { 4743d60874cdSMiklos Szeredi res = ERR_PTR(security_inode_readlink(dentry)); 4744d60874cdSMiklos Szeredi if (!res) 4745d60874cdSMiklos Szeredi res = inode->i_op->get_link(dentry, inode, done); 4746d60874cdSMiklos Szeredi } 4747d60874cdSMiklos Szeredi return res; 4748d60874cdSMiklos Szeredi } 4749d60874cdSMiklos Szeredi EXPORT_SYMBOL(vfs_get_link); 4750d60874cdSMiklos Szeredi 47511da177e4SLinus Torvalds /* get the link contents into pagecache */ 47526b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4753fceef393SAl Viro struct delayed_call *callback) 47541da177e4SLinus Torvalds { 4755ebd09abbSDuane Griffin char *kaddr; 47561da177e4SLinus Torvalds struct page *page; 47576b255391SAl Viro struct address_space *mapping = inode->i_mapping; 47586b255391SAl Viro 4759d3883d4fSAl Viro if (!dentry) { 4760d3883d4fSAl Viro page = find_get_page(mapping, 0); 4761d3883d4fSAl Viro if (!page) 47626b255391SAl Viro return ERR_PTR(-ECHILD); 4763d3883d4fSAl Viro if (!PageUptodate(page)) { 4764d3883d4fSAl Viro put_page(page); 4765d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4766d3883d4fSAl Viro } 4767d3883d4fSAl Viro } else { 4768090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 47691da177e4SLinus Torvalds if (IS_ERR(page)) 47706fe6900eSNick Piggin return (char*)page; 4771d3883d4fSAl Viro } 4772fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 477321fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 477421fc61c7SAl Viro kaddr = page_address(page); 47756b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4776ebd09abbSDuane Griffin return kaddr; 47771da177e4SLinus Torvalds } 47781da177e4SLinus Torvalds 47796b255391SAl Viro EXPORT_SYMBOL(page_get_link); 47801da177e4SLinus Torvalds 4781fceef393SAl Viro void page_put_link(void *arg) 47821da177e4SLinus Torvalds { 4783fceef393SAl Viro put_page(arg); 47841da177e4SLinus Torvalds } 47854d359507SAl Viro EXPORT_SYMBOL(page_put_link); 47861da177e4SLinus Torvalds 4787aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4788aa80deabSAl Viro { 4789fceef393SAl Viro DEFINE_DELAYED_CALL(done); 47906b255391SAl Viro int res = readlink_copy(buffer, buflen, 47916b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4792fceef393SAl Viro &done)); 4793fceef393SAl Viro do_delayed_call(&done); 4794aa80deabSAl Viro return res; 4795aa80deabSAl Viro } 4796aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4797aa80deabSAl Viro 479854566b2cSNick Piggin /* 479954566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 480054566b2cSNick Piggin */ 480154566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 48021da177e4SLinus Torvalds { 48031da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 48040adb25d2SKirill Korotaev struct page *page; 4805afddba49SNick Piggin void *fsdata; 4806beb497abSDmitriy Monakhov int err; 4807c718a975STetsuo Handa unsigned int flags = 0; 480854566b2cSNick Piggin if (nofs) 480954566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 48101da177e4SLinus Torvalds 48117e53cac4SNeilBrown retry: 4812afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 481354566b2cSNick Piggin flags, &page, &fsdata); 48141da177e4SLinus Torvalds if (err) 4815afddba49SNick Piggin goto fail; 4816afddba49SNick Piggin 481721fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4818afddba49SNick Piggin 4819afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4820afddba49SNick Piggin page, fsdata); 48211da177e4SLinus Torvalds if (err < 0) 48221da177e4SLinus Torvalds goto fail; 4823afddba49SNick Piggin if (err < len-1) 4824afddba49SNick Piggin goto retry; 4825afddba49SNick Piggin 48261da177e4SLinus Torvalds mark_inode_dirty(inode); 48271da177e4SLinus Torvalds return 0; 48281da177e4SLinus Torvalds fail: 48291da177e4SLinus Torvalds return err; 48301da177e4SLinus Torvalds } 48314d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 48321da177e4SLinus Torvalds 48330adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 48340adb25d2SKirill Korotaev { 48350adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4836c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 48370adb25d2SKirill Korotaev } 48384d359507SAl Viro EXPORT_SYMBOL(page_symlink); 48390adb25d2SKirill Korotaev 484092e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 48416b255391SAl Viro .get_link = page_get_link, 48421da177e4SLinus Torvalds }; 48431da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4844