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 */ 34323adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 344d594e7ecSAl Viro return 0; 345d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34623adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34723adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 348d594e7ecSAl Viro return 0; 349d594e7ecSAl Viro return -EACCES; 350d594e7ecSAl Viro } 3511da177e4SLinus Torvalds /* 3521da177e4SLinus Torvalds * Read/write DACs are always overridable. 353d594e7ecSAl Viro * Executable DACs are overridable when there is 354d594e7ecSAl Viro * at least one exec bit set. 3551da177e4SLinus Torvalds */ 356d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 35723adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3581da177e4SLinus Torvalds return 0; 3591da177e4SLinus Torvalds 3601da177e4SLinus Torvalds /* 3611da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3621da177e4SLinus Torvalds */ 3637ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 364d594e7ecSAl Viro if (mask == MAY_READ) 36523adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3661da177e4SLinus Torvalds 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. */ 4500bdaea90SDavid Howells if ((sb->s_flags & MS_RDONLY) && 4510bdaea90SDavid Howells (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4520bdaea90SDavid Howells return -EROFS; 4530bdaea90SDavid Howells } 4540bdaea90SDavid Howells return 0; 4550bdaea90SDavid Howells } 4560bdaea90SDavid Howells 4570bdaea90SDavid Howells /** 4580bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4590bdaea90SDavid Howells * @inode: Inode to check permission on 4600bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4610bdaea90SDavid Howells * 4620bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4630bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4640bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4650bdaea90SDavid Howells * 4660bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4670bdaea90SDavid Howells */ 4680bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4690bdaea90SDavid Howells { 4700bdaea90SDavid Howells int retval; 4710bdaea90SDavid Howells 4720bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4730bdaea90SDavid Howells if (retval) 4740bdaea90SDavid Howells return retval; 4750bdaea90SDavid Howells return __inode_permission(inode, mask); 4760bdaea90SDavid Howells } 4774d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4780bdaea90SDavid Howells 4790bdaea90SDavid Howells /** 4805dd784d0SJan Blunck * path_get - get a reference to a path 4815dd784d0SJan Blunck * @path: path to get the reference to 4825dd784d0SJan Blunck * 4835dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4845dd784d0SJan Blunck */ 485dcf787f3SAl Viro void path_get(const struct path *path) 4865dd784d0SJan Blunck { 4875dd784d0SJan Blunck mntget(path->mnt); 4885dd784d0SJan Blunck dget(path->dentry); 4895dd784d0SJan Blunck } 4905dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4915dd784d0SJan Blunck 4925dd784d0SJan Blunck /** 4931d957f9bSJan Blunck * path_put - put a reference to a path 4941d957f9bSJan Blunck * @path: path to put the reference to 4951d957f9bSJan Blunck * 4961d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4971d957f9bSJan Blunck */ 498dcf787f3SAl Viro void path_put(const struct path *path) 4991da177e4SLinus Torvalds { 5001d957f9bSJan Blunck dput(path->dentry); 5011d957f9bSJan Blunck mntput(path->mnt); 5021da177e4SLinus Torvalds } 5031d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 5041da177e4SLinus Torvalds 505894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 5061f55a6ecSAl Viro struct nameidata { 5071f55a6ecSAl Viro struct path path; 5081f55a6ecSAl Viro struct qstr last; 5091f55a6ecSAl Viro struct path root; 5101f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 5111f55a6ecSAl Viro unsigned int flags; 5129883d185SAl Viro unsigned seq, m_seq; 5131f55a6ecSAl Viro int last_type; 5141f55a6ecSAl Viro unsigned depth; 515756daf26SNeilBrown int total_link_count; 516697fc6caSAl Viro struct saved { 517697fc6caSAl Viro struct path link; 518fceef393SAl Viro struct delayed_call done; 519697fc6caSAl Viro const char *name; 5200450b2d1SAl Viro unsigned seq; 521894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5229883d185SAl Viro struct filename *name; 5239883d185SAl Viro struct nameidata *saved; 524fceef393SAl Viro struct inode *link_inode; 5259883d185SAl Viro unsigned root_seq; 5269883d185SAl Viro int dfd; 5271f55a6ecSAl Viro }; 5281f55a6ecSAl Viro 5299883d185SAl Viro static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) 530894bc8c4SAl Viro { 531756daf26SNeilBrown struct nameidata *old = current->nameidata; 532756daf26SNeilBrown p->stack = p->internal; 533c8a53ee5SAl Viro p->dfd = dfd; 534c8a53ee5SAl Viro p->name = name; 535756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 5369883d185SAl Viro p->saved = old; 537756daf26SNeilBrown current->nameidata = p; 538894bc8c4SAl Viro } 539894bc8c4SAl Viro 5409883d185SAl Viro static void restore_nameidata(void) 541894bc8c4SAl Viro { 5429883d185SAl Viro struct nameidata *now = current->nameidata, *old = now->saved; 543756daf26SNeilBrown 544756daf26SNeilBrown current->nameidata = old; 545756daf26SNeilBrown if (old) 546756daf26SNeilBrown old->total_link_count = now->total_link_count; 547e1a63bbcSAl Viro if (now->stack != now->internal) 548756daf26SNeilBrown kfree(now->stack); 549894bc8c4SAl Viro } 550894bc8c4SAl Viro 551894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 552894bc8c4SAl Viro { 553bc40aee0SAl Viro struct saved *p; 554bc40aee0SAl Viro 555bc40aee0SAl Viro if (nd->flags & LOOKUP_RCU) { 556bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 557bc40aee0SAl Viro GFP_ATOMIC); 558bc40aee0SAl Viro if (unlikely(!p)) 559bc40aee0SAl Viro return -ECHILD; 560bc40aee0SAl Viro } else { 561bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 562894bc8c4SAl Viro GFP_KERNEL); 563894bc8c4SAl Viro if (unlikely(!p)) 564894bc8c4SAl Viro return -ENOMEM; 565bc40aee0SAl Viro } 566894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 567894bc8c4SAl Viro nd->stack = p; 568894bc8c4SAl Viro return 0; 569894bc8c4SAl Viro } 570894bc8c4SAl Viro 571397d425dSEric W. Biederman /** 572397d425dSEric W. Biederman * path_connected - Verify that a path->dentry is below path->mnt.mnt_root 573397d425dSEric W. Biederman * @path: nameidate to verify 574397d425dSEric W. Biederman * 575397d425dSEric W. Biederman * Rename can sometimes move a file or directory outside of a bind 576397d425dSEric W. Biederman * mount, path_connected allows those cases to be detected. 577397d425dSEric W. Biederman */ 578397d425dSEric W. Biederman static bool path_connected(const struct path *path) 579397d425dSEric W. Biederman { 580397d425dSEric W. Biederman struct vfsmount *mnt = path->mnt; 581397d425dSEric W. Biederman 582397d425dSEric W. Biederman /* Only bind mounts can have disconnected paths */ 583397d425dSEric W. Biederman if (mnt->mnt_root == mnt->mnt_sb->s_root) 584397d425dSEric W. Biederman return true; 585397d425dSEric W. Biederman 586397d425dSEric W. Biederman return is_subdir(path->dentry, mnt->mnt_root); 587397d425dSEric W. Biederman } 588397d425dSEric W. Biederman 589894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 590894bc8c4SAl Viro { 591da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 592894bc8c4SAl Viro return 0; 593894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 594894bc8c4SAl Viro return 0; 595894bc8c4SAl Viro return __nd_alloc_stack(nd); 596894bc8c4SAl Viro } 597894bc8c4SAl Viro 5987973387aSAl Viro static void drop_links(struct nameidata *nd) 5997973387aSAl Viro { 6007973387aSAl Viro int i = nd->depth; 6017973387aSAl Viro while (i--) { 6027973387aSAl Viro struct saved *last = nd->stack + i; 603fceef393SAl Viro do_delayed_call(&last->done); 604fceef393SAl Viro clear_delayed_call(&last->done); 6057973387aSAl Viro } 6067973387aSAl Viro } 6077973387aSAl Viro 6087973387aSAl Viro static void terminate_walk(struct nameidata *nd) 6097973387aSAl Viro { 6107973387aSAl Viro drop_links(nd); 6117973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 6127973387aSAl Viro int i; 6137973387aSAl Viro path_put(&nd->path); 6147973387aSAl Viro for (i = 0; i < nd->depth; i++) 6157973387aSAl Viro path_put(&nd->stack[i].link); 616102b8af2SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 617102b8af2SAl Viro path_put(&nd->root); 618102b8af2SAl Viro nd->root.mnt = NULL; 619102b8af2SAl Viro } 6207973387aSAl Viro } else { 6217973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 6227973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6237973387aSAl Viro nd->root.mnt = NULL; 6247973387aSAl Viro rcu_read_unlock(); 6257973387aSAl Viro } 6267973387aSAl Viro nd->depth = 0; 6277973387aSAl Viro } 6287973387aSAl Viro 6297973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 6307973387aSAl Viro static bool legitimize_path(struct nameidata *nd, 6317973387aSAl Viro struct path *path, unsigned seq) 6327973387aSAl Viro { 6337973387aSAl Viro int res = __legitimize_mnt(path->mnt, nd->m_seq); 6347973387aSAl Viro if (unlikely(res)) { 6357973387aSAl Viro if (res > 0) 6367973387aSAl Viro path->mnt = NULL; 6377973387aSAl Viro path->dentry = NULL; 6387973387aSAl Viro return false; 6397973387aSAl Viro } 6407973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 6417973387aSAl Viro path->dentry = NULL; 6427973387aSAl Viro return false; 6437973387aSAl Viro } 6447973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6457973387aSAl Viro } 6467973387aSAl Viro 6477973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6487973387aSAl Viro { 6497973387aSAl Viro int i; 6507973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6517973387aSAl Viro struct saved *last = nd->stack + i; 6527973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6537973387aSAl Viro drop_links(nd); 6547973387aSAl Viro nd->depth = i + 1; 6557973387aSAl Viro return false; 6567973387aSAl Viro } 6577973387aSAl Viro } 6587973387aSAl Viro return true; 6597973387aSAl Viro } 6607973387aSAl Viro 66119660af7SAl Viro /* 66231e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 66319660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 66419660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 66557e3715cSMike Marshall * normal reference counts on dentries and vfsmounts to transition to ref-walk 66619660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 66719660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 66819660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 66919660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 67031e6b01fSNick Piggin */ 67131e6b01fSNick Piggin 67231e6b01fSNick Piggin /** 67319660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 67419660af7SAl Viro * @nd: nameidata pathwalk data 67519660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 6766e9918b7SAl Viro * @seq: seq number to check dentry against 67739191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 67831e6b01fSNick Piggin * 67919660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 68019660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 68119660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 6827973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6837973387aSAl Viro * terminate_walk(). 68431e6b01fSNick Piggin */ 6856e9918b7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry, unsigned seq) 68631e6b01fSNick Piggin { 68731e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 68831e6b01fSNick Piggin 68931e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 690e5c832d5SLinus Torvalds 691e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6927973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6937973387aSAl Viro goto out2; 6947973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 6957973387aSAl Viro goto out2; 6967973387aSAl Viro if (unlikely(!lockref_get_not_dead(&parent->d_lockref))) 6977973387aSAl Viro goto out1; 69848a066e7SAl Viro 69915570086SLinus Torvalds /* 70015570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 70115570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 70215570086SLinus Torvalds * 70315570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 70415570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 70515570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 70615570086SLinus Torvalds * since we checked the sequence number of the parent after we got 70715570086SLinus Torvalds * the child sequence number. So we know the parent must still 70815570086SLinus Torvalds * be valid if the child sequence number is still valid. 70915570086SLinus Torvalds */ 71019660af7SAl Viro if (!dentry) { 711e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 712e5c832d5SLinus Torvalds goto out; 71319660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 71419660af7SAl Viro } else { 715e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 716e5c832d5SLinus Torvalds goto out; 7176e9918b7SAl Viro if (read_seqcount_retry(&dentry->d_seq, seq)) 718e5c832d5SLinus Torvalds goto drop_dentry; 71919660af7SAl Viro } 720e5c832d5SLinus Torvalds 721e5c832d5SLinus Torvalds /* 722e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 723e5c832d5SLinus Torvalds * still valid and get it if required. 724e5c832d5SLinus Torvalds */ 725e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 7265a8d87e8SAl Viro if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq))) { 7275a8d87e8SAl Viro rcu_read_unlock(); 7285a8d87e8SAl Viro dput(dentry); 7295a8d87e8SAl Viro return -ECHILD; 7307973387aSAl Viro } 73131e6b01fSNick Piggin } 73231e6b01fSNick Piggin 7338b61e74fSAl Viro rcu_read_unlock(); 73431e6b01fSNick Piggin return 0; 73519660af7SAl Viro 736e5c832d5SLinus Torvalds drop_dentry: 7378b61e74fSAl Viro rcu_read_unlock(); 738e5c832d5SLinus Torvalds dput(dentry); 739d0d27277SLinus Torvalds goto drop_root_mnt; 7407973387aSAl Viro out2: 7417973387aSAl Viro nd->path.mnt = NULL; 7427973387aSAl Viro out1: 7437973387aSAl Viro nd->path.dentry = NULL; 744e5c832d5SLinus Torvalds out: 7458b61e74fSAl Viro rcu_read_unlock(); 746d0d27277SLinus Torvalds drop_root_mnt: 747d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 748d0d27277SLinus Torvalds nd->root.mnt = NULL; 74931e6b01fSNick Piggin return -ECHILD; 75031e6b01fSNick Piggin } 75131e6b01fSNick Piggin 7524ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 75334286d66SNick Piggin { 7544ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 75534286d66SNick Piggin } 75634286d66SNick Piggin 7579f1fafeeSAl Viro /** 7589f1fafeeSAl Viro * complete_walk - successful completion of path walk 7599f1fafeeSAl Viro * @nd: pointer nameidata 76039159de2SJeff Layton * 7619f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7629f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7639f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7649f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7659f1fafeeSAl Viro * need to drop nd->path. 76639159de2SJeff Layton */ 7679f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 76839159de2SJeff Layton { 76916c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 77039159de2SJeff Layton int status; 77139159de2SJeff Layton 7729f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 7739f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7749f1fafeeSAl Viro nd->root.mnt = NULL; 7756e9918b7SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 77648a066e7SAl Viro return -ECHILD; 77748a066e7SAl Viro } 7789f1fafeeSAl Viro 77916c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 78039159de2SJeff Layton return 0; 78139159de2SJeff Layton 782ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 78316c2cd71SAl Viro return 0; 78416c2cd71SAl Viro 785ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 78639159de2SJeff Layton if (status > 0) 78739159de2SJeff Layton return 0; 78839159de2SJeff Layton 78916c2cd71SAl Viro if (!status) 79039159de2SJeff Layton status = -ESTALE; 79116c2cd71SAl Viro 79239159de2SJeff Layton return status; 79339159de2SJeff Layton } 79439159de2SJeff Layton 79518d8c860SAl Viro static void set_root(struct nameidata *nd) 7962a737871SAl Viro { 79731e6b01fSNick Piggin struct fs_struct *fs = current->fs; 7989e6697e2SAl Viro 7999e6697e2SAl Viro if (nd->flags & LOOKUP_RCU) { 8008f47a016SAl Viro unsigned seq; 801c28cc364SNick Piggin 802c28cc364SNick Piggin do { 803c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 80431e6b01fSNick Piggin nd->root = fs->root; 8058f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 806c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 8079e6697e2SAl Viro } else { 8089e6697e2SAl Viro get_fs_root(fs, &nd->root); 8099e6697e2SAl Viro } 81031e6b01fSNick Piggin } 81131e6b01fSNick Piggin 8121d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 813051d3812SIan Kent { 814051d3812SIan Kent dput(path->dentry); 8154ac91378SJan Blunck if (path->mnt != nd->path.mnt) 816051d3812SIan Kent mntput(path->mnt); 817051d3812SIan Kent } 818051d3812SIan Kent 8197b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8207b9337aaSNick Piggin struct nameidata *nd) 821051d3812SIan Kent { 82231e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8234ac91378SJan Blunck dput(nd->path.dentry); 82431e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8254ac91378SJan Blunck mntput(nd->path.mnt); 8269a229683SHuang Shijie } 82731e6b01fSNick Piggin nd->path.mnt = path->mnt; 8284ac91378SJan Blunck nd->path.dentry = path->dentry; 829051d3812SIan Kent } 830051d3812SIan Kent 831248fb5b9SAl Viro static int nd_jump_root(struct nameidata *nd) 832248fb5b9SAl Viro { 833248fb5b9SAl Viro if (nd->flags & LOOKUP_RCU) { 834248fb5b9SAl Viro struct dentry *d; 835248fb5b9SAl Viro nd->path = nd->root; 836248fb5b9SAl Viro d = nd->path.dentry; 837248fb5b9SAl Viro nd->inode = d->d_inode; 838248fb5b9SAl Viro nd->seq = nd->root_seq; 839248fb5b9SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 840248fb5b9SAl Viro return -ECHILD; 841248fb5b9SAl Viro } else { 842248fb5b9SAl Viro path_put(&nd->path); 843248fb5b9SAl Viro nd->path = nd->root; 844248fb5b9SAl Viro path_get(&nd->path); 845248fb5b9SAl Viro nd->inode = nd->path.dentry->d_inode; 846248fb5b9SAl Viro } 847248fb5b9SAl Viro nd->flags |= LOOKUP_JUMPED; 848248fb5b9SAl Viro return 0; 849248fb5b9SAl Viro } 850248fb5b9SAl Viro 851b5fb63c1SChristoph Hellwig /* 8526b255391SAl Viro * Helper to directly jump to a known parsed path from ->get_link, 853b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 854b5fb63c1SChristoph Hellwig */ 8556e77137bSAl Viro void nd_jump_link(struct path *path) 856b5fb63c1SChristoph Hellwig { 8576e77137bSAl Viro struct nameidata *nd = current->nameidata; 858b5fb63c1SChristoph Hellwig path_put(&nd->path); 859b5fb63c1SChristoph Hellwig 860b5fb63c1SChristoph Hellwig nd->path = *path; 861b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 862b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 863b5fb63c1SChristoph Hellwig } 864b5fb63c1SChristoph Hellwig 865b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 866574197e0SAl Viro { 86721c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 868fceef393SAl Viro do_delayed_call(&last->done); 8696548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 870b9ff4429SAl Viro path_put(&last->link); 871574197e0SAl Viro } 872574197e0SAl Viro 873561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 874561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 875800179c9SKees Cook 876800179c9SKees Cook /** 877800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 87855852635SRandy Dunlap * @nd: nameidata pathwalk data 879800179c9SKees Cook * 880800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 881800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 882800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 883800179c9SKees Cook * processes from failing races against path names that may change out 884800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 885800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 886800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 887800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 888800179c9SKees Cook * 889800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 890800179c9SKees Cook */ 891fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 892800179c9SKees Cook { 893800179c9SKees Cook const struct inode *inode; 894800179c9SKees Cook const struct inode *parent; 8952d7f9e2aSSeth Forshee kuid_t puid; 896800179c9SKees Cook 897800179c9SKees Cook if (!sysctl_protected_symlinks) 898800179c9SKees Cook return 0; 899800179c9SKees Cook 900800179c9SKees Cook /* Allowed if owner and follower match. */ 901fceef393SAl Viro inode = nd->link_inode; 90281abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 903800179c9SKees Cook return 0; 904800179c9SKees Cook 905800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 906aa65fa35SAl Viro parent = nd->inode; 907800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 908800179c9SKees Cook return 0; 909800179c9SKees Cook 910800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 9112d7f9e2aSSeth Forshee puid = parent->i_uid; 9122d7f9e2aSSeth Forshee if (uid_valid(puid) && uid_eq(puid, inode->i_uid)) 913800179c9SKees Cook return 0; 914800179c9SKees Cook 91531956502SAl Viro if (nd->flags & LOOKUP_RCU) 91631956502SAl Viro return -ECHILD; 91731956502SAl Viro 9181cf2665bSAl Viro audit_log_link_denied("follow_link", &nd->stack[0].link); 919800179c9SKees Cook return -EACCES; 920800179c9SKees Cook } 921800179c9SKees Cook 922800179c9SKees Cook /** 923800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 924800179c9SKees Cook * @inode: the source inode to hardlink from 925800179c9SKees Cook * 926800179c9SKees Cook * Return false if at least one of the following conditions: 927800179c9SKees Cook * - inode is not a regular file 928800179c9SKees Cook * - inode is setuid 929800179c9SKees Cook * - inode is setgid and group-exec 930800179c9SKees Cook * - access failure for read and write 931800179c9SKees Cook * 932800179c9SKees Cook * Otherwise returns true. 933800179c9SKees Cook */ 934800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 935800179c9SKees Cook { 936800179c9SKees Cook umode_t mode = inode->i_mode; 937800179c9SKees Cook 938800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 939800179c9SKees Cook if (!S_ISREG(mode)) 940800179c9SKees Cook return false; 941800179c9SKees Cook 942800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 943800179c9SKees Cook if (mode & S_ISUID) 944800179c9SKees Cook return false; 945800179c9SKees Cook 946800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 947800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 948800179c9SKees Cook return false; 949800179c9SKees Cook 950800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 951800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 952800179c9SKees Cook return false; 953800179c9SKees Cook 954800179c9SKees Cook return true; 955800179c9SKees Cook } 956800179c9SKees Cook 957800179c9SKees Cook /** 958800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 959800179c9SKees Cook * @link: the source to hardlink from 960800179c9SKees Cook * 961800179c9SKees Cook * Block hardlink when all of: 962800179c9SKees Cook * - sysctl_protected_hardlinks enabled 963800179c9SKees Cook * - fsuid does not match inode 964800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 965f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 966800179c9SKees Cook * 967800179c9SKees Cook * Returns 0 if successful, -ve on error. 968800179c9SKees Cook */ 969800179c9SKees Cook static int may_linkat(struct path *link) 970800179c9SKees Cook { 971800179c9SKees Cook struct inode *inode; 972800179c9SKees Cook 973800179c9SKees Cook if (!sysctl_protected_hardlinks) 974800179c9SKees Cook return 0; 975800179c9SKees Cook 976800179c9SKees Cook inode = link->dentry->d_inode; 977800179c9SKees Cook 978800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 979800179c9SKees Cook * otherwise, it must be a safe source. 980800179c9SKees Cook */ 981f2ca3796SDirk Steinmetz if (inode_owner_or_capable(inode) || safe_hardlink_source(inode)) 982800179c9SKees Cook return 0; 983800179c9SKees Cook 984a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 985800179c9SKees Cook return -EPERM; 986800179c9SKees Cook } 987800179c9SKees Cook 9883b2e7f75SAl Viro static __always_inline 9893b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 9901da177e4SLinus Torvalds { 991ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 9921cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 993fceef393SAl Viro struct inode *inode = nd->link_inode; 9946d7b5aaeSAl Viro int error; 9950a959df5SAl Viro const char *res; 9961da177e4SLinus Torvalds 9978fa9dd24SNeilBrown if (!(nd->flags & LOOKUP_RCU)) { 9988fa9dd24SNeilBrown touch_atime(&last->link); 9998fa9dd24SNeilBrown cond_resched(); 1000598e3c8fSMiklos Szeredi } else if (atime_needs_update_rcu(&last->link, inode)) { 10018fa9dd24SNeilBrown if (unlikely(unlazy_walk(nd, NULL, 0))) 10028fa9dd24SNeilBrown return ERR_PTR(-ECHILD); 10038fa9dd24SNeilBrown touch_atime(&last->link); 10048fa9dd24SNeilBrown } 10058fa9dd24SNeilBrown 1006bda0be7aSNeilBrown error = security_inode_follow_link(dentry, inode, 1007bda0be7aSNeilBrown nd->flags & LOOKUP_RCU); 1008bda0be7aSNeilBrown if (unlikely(error)) 10096920a440SAl Viro return ERR_PTR(error); 101036f3b4f6SAl Viro 101186acdca1SAl Viro nd->last_type = LAST_BIND; 1012d4dee48bSAl Viro res = inode->i_link; 1013d4dee48bSAl Viro if (!res) { 1014fceef393SAl Viro const char * (*get)(struct dentry *, struct inode *, 1015fceef393SAl Viro struct delayed_call *); 1016fceef393SAl Viro get = inode->i_op->get_link; 10178c1b4566SAl Viro if (nd->flags & LOOKUP_RCU) { 1018fceef393SAl Viro res = get(NULL, inode, &last->done); 10196b255391SAl Viro if (res == ERR_PTR(-ECHILD)) { 10208c1b4566SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 10218c1b4566SAl Viro return ERR_PTR(-ECHILD); 1022fceef393SAl Viro res = get(dentry, inode, &last->done); 10238c1b4566SAl Viro } 10246b255391SAl Viro } else { 1025fceef393SAl Viro res = get(dentry, inode, &last->done); 10266b255391SAl Viro } 1027fceef393SAl Viro if (IS_ERR_OR_NULL(res)) 1028fab51e8aSAl Viro return res; 10290a959df5SAl Viro } 1030fab51e8aSAl Viro if (*res == '/') { 1031fab51e8aSAl Viro if (!nd->root.mnt) 1032fab51e8aSAl Viro set_root(nd); 1033248fb5b9SAl Viro if (unlikely(nd_jump_root(nd))) 1034fab51e8aSAl Viro return ERR_PTR(-ECHILD); 1035fab51e8aSAl Viro while (unlikely(*++res == '/')) 1036fab51e8aSAl Viro ; 1037fab51e8aSAl Viro } 1038fab51e8aSAl Viro if (!*res) 1039fab51e8aSAl Viro res = NULL; 10400a959df5SAl Viro return res; 10410a959df5SAl Viro } 10426d7b5aaeSAl Viro 1043f015f126SDavid Howells /* 1044f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1045f015f126SDavid Howells * 1046f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1047f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1048f015f126SDavid Howells * Up is towards /. 1049f015f126SDavid Howells * 1050f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1051f015f126SDavid Howells * root. 1052f015f126SDavid Howells */ 1053bab77ebfSAl Viro int follow_up(struct path *path) 10541da177e4SLinus Torvalds { 10550714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 10560714a533SAl Viro struct mount *parent; 10571da177e4SLinus Torvalds struct dentry *mountpoint; 105899b7db7bSNick Piggin 105948a066e7SAl Viro read_seqlock_excl(&mount_lock); 10600714a533SAl Viro parent = mnt->mnt_parent; 10613c0a6163SAl Viro if (parent == mnt) { 106248a066e7SAl Viro read_sequnlock_excl(&mount_lock); 10631da177e4SLinus Torvalds return 0; 10641da177e4SLinus Torvalds } 10650714a533SAl Viro mntget(&parent->mnt); 1066a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 106748a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1068bab77ebfSAl Viro dput(path->dentry); 1069bab77ebfSAl Viro path->dentry = mountpoint; 1070bab77ebfSAl Viro mntput(path->mnt); 10710714a533SAl Viro path->mnt = &parent->mnt; 10721da177e4SLinus Torvalds return 1; 10731da177e4SLinus Torvalds } 10744d359507SAl Viro EXPORT_SYMBOL(follow_up); 10751da177e4SLinus Torvalds 1076b5c84bf6SNick Piggin /* 10779875cf80SDavid Howells * Perform an automount 10789875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 10799875cf80SDavid Howells * were called with. 10801da177e4SLinus Torvalds */ 1081756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 10829875cf80SDavid Howells bool *need_mntput) 108331e6b01fSNick Piggin { 10849875cf80SDavid Howells struct vfsmount *mnt; 1085aeaa4a79SEric W. Biederman const struct cred *old_cred; 1086ea5b778aSDavid Howells int err; 10879875cf80SDavid Howells 10889875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 10899875cf80SDavid Howells return -EREMOTE; 10909875cf80SDavid Howells 10910ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 10920ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 10930ec26fd0SMiklos Szeredi * the name. 10940ec26fd0SMiklos Szeredi * 10950ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 10965a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 10970ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 10980ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 10990ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 11000ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 11015a30d8a2SDavid Howells */ 1102756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 1103d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 11045a30d8a2SDavid Howells path->dentry->d_inode) 11059875cf80SDavid Howells return -EISDIR; 11060ec26fd0SMiklos Szeredi 1107aeaa4a79SEric W. Biederman if (path->dentry->d_sb->s_user_ns != &init_user_ns) 1108aeaa4a79SEric W. Biederman return -EACCES; 1109aeaa4a79SEric W. Biederman 1110756daf26SNeilBrown nd->total_link_count++; 1111756daf26SNeilBrown if (nd->total_link_count >= 40) 11129875cf80SDavid Howells return -ELOOP; 11139875cf80SDavid Howells 1114aeaa4a79SEric W. Biederman old_cred = override_creds(&init_cred); 11159875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 1116aeaa4a79SEric W. Biederman revert_creds(old_cred); 11179875cf80SDavid Howells if (IS_ERR(mnt)) { 11189875cf80SDavid Howells /* 11199875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 11209875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 11219875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 11229875cf80SDavid Howells * 11239875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 11249875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 11259875cf80SDavid Howells * the path is inaccessible and we should say so. 11269875cf80SDavid Howells */ 1127756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 11289875cf80SDavid Howells return -EREMOTE; 11299875cf80SDavid Howells return PTR_ERR(mnt); 113031e6b01fSNick Piggin } 1131ea5b778aSDavid Howells 11329875cf80SDavid Howells if (!mnt) /* mount collision */ 11339875cf80SDavid Howells return 0; 11349875cf80SDavid Howells 11358aef1884SAl Viro if (!*need_mntput) { 11368aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 11378aef1884SAl Viro mntget(path->mnt); 11388aef1884SAl Viro *need_mntput = true; 11398aef1884SAl Viro } 114019a167afSAl Viro err = finish_automount(mnt, path); 1141ea5b778aSDavid Howells 1142ea5b778aSDavid Howells switch (err) { 1143ea5b778aSDavid Howells case -EBUSY: 1144ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 114519a167afSAl Viro return 0; 1146ea5b778aSDavid Howells case 0: 11478aef1884SAl Viro path_put(path); 11489875cf80SDavid Howells path->mnt = mnt; 11499875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 11509875cf80SDavid Howells return 0; 115119a167afSAl Viro default: 115219a167afSAl Viro return err; 11539875cf80SDavid Howells } 115419a167afSAl Viro 1155ea5b778aSDavid Howells } 11569875cf80SDavid Howells 11579875cf80SDavid Howells /* 11589875cf80SDavid Howells * Handle a dentry that is managed in some way. 1159cc53ce53SDavid Howells * - Flagged for transit management (autofs) 11609875cf80SDavid Howells * - Flagged as mountpoint 11619875cf80SDavid Howells * - Flagged as automount point 11629875cf80SDavid Howells * 11639875cf80SDavid Howells * This may only be called in refwalk mode. 11649875cf80SDavid Howells * 11659875cf80SDavid Howells * Serialization is taken care of in namespace.c 11669875cf80SDavid Howells */ 1167756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 11689875cf80SDavid Howells { 11698aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 11709875cf80SDavid Howells unsigned managed; 11719875cf80SDavid Howells bool need_mntput = false; 11728aef1884SAl Viro int ret = 0; 11739875cf80SDavid Howells 11749875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 11759875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 11769875cf80SDavid Howells * the components of that value change under us */ 11779875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 11789875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 11799875cf80SDavid Howells unlikely(managed != 0)) { 1180cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1181cc53ce53SDavid Howells * being held. */ 1182cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1183cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1184cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1185fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1186cc53ce53SDavid Howells if (ret < 0) 11878aef1884SAl Viro break; 1188cc53ce53SDavid Howells } 1189cc53ce53SDavid Howells 11909875cf80SDavid Howells /* Transit to a mounted filesystem. */ 11919875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 11929875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 11939875cf80SDavid Howells if (mounted) { 11949875cf80SDavid Howells dput(path->dentry); 11959875cf80SDavid Howells if (need_mntput) 1196463ffb2eSAl Viro mntput(path->mnt); 1197463ffb2eSAl Viro path->mnt = mounted; 1198463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 11999875cf80SDavid Howells need_mntput = true; 12009875cf80SDavid Howells continue; 1201463ffb2eSAl Viro } 1202463ffb2eSAl Viro 12039875cf80SDavid Howells /* Something is mounted on this dentry in another 12049875cf80SDavid Howells * namespace and/or whatever was mounted there in this 120548a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 120648a066e7SAl Viro * get it */ 12071da177e4SLinus Torvalds } 12089875cf80SDavid Howells 12099875cf80SDavid Howells /* Handle an automount point */ 12109875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1211756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 12129875cf80SDavid Howells if (ret < 0) 12138aef1884SAl Viro break; 12149875cf80SDavid Howells continue; 12159875cf80SDavid Howells } 12169875cf80SDavid Howells 12179875cf80SDavid Howells /* We didn't change the current path point */ 12189875cf80SDavid Howells break; 12199875cf80SDavid Howells } 12208aef1884SAl Viro 12218aef1884SAl Viro if (need_mntput && path->mnt == mnt) 12228aef1884SAl Viro mntput(path->mnt); 1223e9742b53SAl Viro if (ret == -EISDIR || !ret) 1224e9742b53SAl Viro ret = 1; 12258402752eSAl Viro if (need_mntput) 12268402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 12278402752eSAl Viro if (unlikely(ret < 0)) 12288402752eSAl Viro path_put_conditional(path, nd); 12298402752eSAl Viro return ret; 12301da177e4SLinus Torvalds } 12311da177e4SLinus Torvalds 1232cc53ce53SDavid Howells int follow_down_one(struct path *path) 12331da177e4SLinus Torvalds { 12341da177e4SLinus Torvalds struct vfsmount *mounted; 12351da177e4SLinus Torvalds 12361c755af4SAl Viro mounted = lookup_mnt(path); 12371da177e4SLinus Torvalds if (mounted) { 12389393bd07SAl Viro dput(path->dentry); 12399393bd07SAl Viro mntput(path->mnt); 12409393bd07SAl Viro path->mnt = mounted; 12419393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12421da177e4SLinus Torvalds return 1; 12431da177e4SLinus Torvalds } 12441da177e4SLinus Torvalds return 0; 12451da177e4SLinus Torvalds } 12464d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12471da177e4SLinus Torvalds 1248fb5f51c7SIan Kent static inline int managed_dentry_rcu(const struct path *path) 124962a7375eSIan Kent { 1250fb5f51c7SIan Kent return (path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1251fb5f51c7SIan Kent path->dentry->d_op->d_manage(path, true) : 0; 125262a7375eSIan Kent } 125362a7375eSIan Kent 12549875cf80SDavid Howells /* 1255287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1256287548e4SAl Viro * we meet a managed dentry that would need blocking. 12579875cf80SDavid Howells */ 12589875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1259254cf582SAl Viro struct inode **inode, unsigned *seqp) 12609875cf80SDavid Howells { 126162a7375eSIan Kent for (;;) { 1262c7105365SAl Viro struct mount *mounted; 126362a7375eSIan Kent /* 126462a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 126562a7375eSIan Kent * that wants to block transit. 126662a7375eSIan Kent */ 1267fb5f51c7SIan Kent switch (managed_dentry_rcu(path)) { 1268b8faf035SNeilBrown case -ECHILD: 1269b8faf035SNeilBrown default: 1270ab90911fSDavid Howells return false; 1271b8faf035SNeilBrown case -EISDIR: 1272b8faf035SNeilBrown return true; 1273b8faf035SNeilBrown case 0: 1274b8faf035SNeilBrown break; 1275b8faf035SNeilBrown } 127662a7375eSIan Kent 127762a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1278b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 127962a7375eSIan Kent 1280474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 12819875cf80SDavid Howells if (!mounted) 12829875cf80SDavid Howells break; 1283c7105365SAl Viro path->mnt = &mounted->mnt; 1284c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1285a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1286254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 128759430262SLinus Torvalds /* 128859430262SLinus Torvalds * Update the inode too. We don't need to re-check the 128959430262SLinus Torvalds * dentry sequence number here after this d_inode read, 129059430262SLinus Torvalds * because a mount-point is always pinned. 129159430262SLinus Torvalds */ 129259430262SLinus Torvalds *inode = path->dentry->d_inode; 12939875cf80SDavid Howells } 1294f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1295b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1296287548e4SAl Viro } 1297287548e4SAl Viro 129831e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 129931e6b01fSNick Piggin { 13004023bfc9SAl Viro struct inode *inode = nd->inode; 130131e6b01fSNick Piggin 130231e6b01fSNick Piggin while (1) { 1303aed434adSAl Viro if (path_equal(&nd->path, &nd->root)) 130431e6b01fSNick Piggin break; 130531e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 130631e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 130731e6b01fSNick Piggin struct dentry *parent = old->d_parent; 130831e6b01fSNick Piggin unsigned seq; 130931e6b01fSNick Piggin 13104023bfc9SAl Viro inode = parent->d_inode; 131131e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 1312aed434adSAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 1313aed434adSAl Viro return -ECHILD; 131431e6b01fSNick Piggin nd->path.dentry = parent; 131531e6b01fSNick Piggin nd->seq = seq; 1316397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 1317397d425dSEric W. Biederman return -ENOENT; 131831e6b01fSNick Piggin break; 1319aed434adSAl Viro } else { 1320aed434adSAl Viro struct mount *mnt = real_mount(nd->path.mnt); 1321aed434adSAl Viro struct mount *mparent = mnt->mnt_parent; 1322aed434adSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1323aed434adSAl Viro struct inode *inode2 = mountpoint->d_inode; 1324aed434adSAl Viro unsigned seq = read_seqcount_begin(&mountpoint->d_seq); 1325aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1326aed434adSAl Viro return -ECHILD; 1327aed434adSAl Viro if (&mparent->mnt == nd->path.mnt) 132831e6b01fSNick Piggin break; 1329aed434adSAl Viro /* we know that mountpoint was pinned */ 1330aed434adSAl Viro nd->path.dentry = mountpoint; 1331aed434adSAl Viro nd->path.mnt = &mparent->mnt; 1332aed434adSAl Viro inode = inode2; 1333aed434adSAl Viro nd->seq = seq; 133431e6b01fSNick Piggin } 1335aed434adSAl Viro } 1336aed434adSAl Viro while (unlikely(d_mountpoint(nd->path.dentry))) { 1337b37199e6SAl Viro struct mount *mounted; 1338b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1339aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1340aed434adSAl Viro return -ECHILD; 1341b37199e6SAl Viro if (!mounted) 1342b37199e6SAl Viro break; 1343b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1344b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 13454023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1346b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1347b37199e6SAl Viro } 13484023bfc9SAl Viro nd->inode = inode; 134931e6b01fSNick Piggin return 0; 135031e6b01fSNick Piggin } 135131e6b01fSNick Piggin 13529875cf80SDavid Howells /* 1353cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1354cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1355cc53ce53SDavid Howells * caller is permitted to proceed or not. 1356cc53ce53SDavid Howells */ 13577cc90cc3SAl Viro int follow_down(struct path *path) 1358cc53ce53SDavid Howells { 1359cc53ce53SDavid Howells unsigned managed; 1360cc53ce53SDavid Howells int ret; 1361cc53ce53SDavid Howells 1362cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1363cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1364cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1365cc53ce53SDavid Howells * being held. 1366cc53ce53SDavid Howells * 1367cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1368cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1369cc53ce53SDavid Howells * other than its daemon the right to mount on its 1370cc53ce53SDavid Howells * superstructure. 1371cc53ce53SDavid Howells * 1372cc53ce53SDavid Howells * The filesystem may sleep at this point. 1373cc53ce53SDavid Howells */ 1374cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1375cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1376cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1377fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1378cc53ce53SDavid Howells if (ret < 0) 1379cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1380cc53ce53SDavid Howells } 1381cc53ce53SDavid Howells 1382cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1383cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1384cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1385cc53ce53SDavid Howells if (!mounted) 1386cc53ce53SDavid Howells break; 1387cc53ce53SDavid Howells dput(path->dentry); 1388cc53ce53SDavid Howells mntput(path->mnt); 1389cc53ce53SDavid Howells path->mnt = mounted; 1390cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1391cc53ce53SDavid Howells continue; 1392cc53ce53SDavid Howells } 1393cc53ce53SDavid Howells 1394cc53ce53SDavid Howells /* Don't handle automount points here */ 1395cc53ce53SDavid Howells break; 1396cc53ce53SDavid Howells } 1397cc53ce53SDavid Howells return 0; 1398cc53ce53SDavid Howells } 13994d359507SAl Viro EXPORT_SYMBOL(follow_down); 1400cc53ce53SDavid Howells 1401cc53ce53SDavid Howells /* 14029875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 14039875cf80SDavid Howells */ 14049875cf80SDavid Howells static void follow_mount(struct path *path) 14059875cf80SDavid Howells { 14069875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 14079875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 14089875cf80SDavid Howells if (!mounted) 14099875cf80SDavid Howells break; 14109875cf80SDavid Howells dput(path->dentry); 14119875cf80SDavid Howells mntput(path->mnt); 14129875cf80SDavid Howells path->mnt = mounted; 14139875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 14149875cf80SDavid Howells } 14159875cf80SDavid Howells } 14169875cf80SDavid Howells 1417eedf265aSEric W. Biederman static int path_parent_directory(struct path *path) 1418eedf265aSEric W. Biederman { 1419eedf265aSEric W. Biederman struct dentry *old = path->dentry; 1420eedf265aSEric W. Biederman /* rare case of legitimate dget_parent()... */ 1421eedf265aSEric W. Biederman path->dentry = dget_parent(path->dentry); 1422eedf265aSEric W. Biederman dput(old); 1423eedf265aSEric W. Biederman if (unlikely(!path_connected(path))) 1424eedf265aSEric W. Biederman return -ENOENT; 1425eedf265aSEric W. Biederman return 0; 1426eedf265aSEric W. Biederman } 1427eedf265aSEric W. Biederman 1428397d425dSEric W. Biederman static int follow_dotdot(struct nameidata *nd) 14291da177e4SLinus Torvalds { 14301da177e4SLinus Torvalds while(1) { 14312a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 14322a737871SAl Viro nd->path.mnt == nd->root.mnt) { 14331da177e4SLinus Torvalds break; 14341da177e4SLinus Torvalds } 14354ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 1436eedf265aSEric W. Biederman int ret = path_parent_directory(&nd->path); 1437eedf265aSEric W. Biederman if (ret) 1438eedf265aSEric W. Biederman return ret; 14391da177e4SLinus Torvalds break; 14401da177e4SLinus Torvalds } 14413088dd70SAl Viro if (!follow_up(&nd->path)) 14421da177e4SLinus Torvalds break; 14431da177e4SLinus Torvalds } 144479ed0226SAl Viro follow_mount(&nd->path); 144531e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 1446397d425dSEric W. Biederman return 0; 14471da177e4SLinus Torvalds } 14481da177e4SLinus Torvalds 14491da177e4SLinus Torvalds /* 1450f4fdace9SOleg Drokin * This looks up the name in dcache and possibly revalidates the found dentry. 1451f4fdace9SOleg Drokin * NULL is returned if the dentry does not exist in the cache. 1452baa03890SNick Piggin */ 1453e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1454e3c13928SAl Viro struct dentry *dir, 14556c51e513SAl Viro unsigned int flags) 1456baa03890SNick Piggin { 1457baa03890SNick Piggin struct dentry *dentry; 1458bad61189SMiklos Szeredi int error; 1459baa03890SNick Piggin 1460bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1461bad61189SMiklos Szeredi if (dentry) { 146239e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1463201f956eSAl Viro error = d_revalidate(dentry, flags); 1464bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 146574ff0ffcSAl Viro if (!error) 14665542aa2fSEric W. Biederman d_invalidate(dentry); 1467bad61189SMiklos Szeredi dput(dentry); 146874ff0ffcSAl Viro return ERR_PTR(error); 1469bad61189SMiklos Szeredi } 1470bad61189SMiklos Szeredi } 1471bad61189SMiklos Szeredi } 1472baa03890SNick Piggin return dentry; 1473baa03890SNick Piggin } 1474baa03890SNick Piggin 1475baa03890SNick Piggin /* 147613a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 147713a2c3beSJ. Bruce Fields * unhashed. 1478bad61189SMiklos Szeredi * 1479bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 148044396f4bSJosef Bacik */ 1481bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 148272bd866aSAl Viro unsigned int flags) 148344396f4bSJosef Bacik { 148444396f4bSJosef Bacik struct dentry *old; 148544396f4bSJosef Bacik 148644396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1487bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1488e188dc02SMiklos Szeredi dput(dentry); 148944396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1490e188dc02SMiklos Szeredi } 149144396f4bSJosef Bacik 149272bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 149344396f4bSJosef Bacik if (unlikely(old)) { 149444396f4bSJosef Bacik dput(dentry); 149544396f4bSJosef Bacik dentry = old; 149644396f4bSJosef Bacik } 149744396f4bSJosef Bacik return dentry; 149844396f4bSJosef Bacik } 149944396f4bSJosef Bacik 1500e3c13928SAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 150172bd866aSAl Viro struct dentry *base, unsigned int flags) 1502a3255546SAl Viro { 15036c51e513SAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 1504a3255546SAl Viro 15056c51e513SAl Viro if (dentry) 1506a3255546SAl Viro return dentry; 1507bad61189SMiklos Szeredi 15086c51e513SAl Viro dentry = d_alloc(base, name); 15096c51e513SAl Viro if (unlikely(!dentry)) 15106c51e513SAl Viro return ERR_PTR(-ENOMEM); 15116c51e513SAl Viro 151272bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1513a3255546SAl Viro } 1514a3255546SAl Viro 1515e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 1516254cf582SAl Viro struct path *path, struct inode **inode, 1517254cf582SAl Viro unsigned *seqp) 15181da177e4SLinus Torvalds { 15194ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 152031e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 15215a18fff2SAl Viro int status = 1; 15229875cf80SDavid Howells int err; 15239875cf80SDavid Howells 15243cac260aSAl Viro /* 1525b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 15265d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 15275d0f49c1SAl Viro * going to fall back to non-racy lookup. 1528b04f784eSNick Piggin */ 152931e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 153031e6b01fSNick Piggin unsigned seq; 1531766c4cbfSAl Viro bool negative; 1532da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15335d0f49c1SAl Viro if (unlikely(!dentry)) { 15345d0f49c1SAl Viro if (unlazy_walk(nd, NULL, 0)) 15355d0f49c1SAl Viro return -ECHILD; 1536e9742b53SAl Viro return 0; 15375d0f49c1SAl Viro } 15385a18fff2SAl Viro 153912f8ad4bSLinus Torvalds /* 154012f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 154112f8ad4bSLinus Torvalds * the dentry name information from lookup. 154212f8ad4bSLinus Torvalds */ 154363afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1544766c4cbfSAl Viro negative = d_is_negative(dentry); 15455d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 154612f8ad4bSLinus Torvalds return -ECHILD; 154712f8ad4bSLinus Torvalds 154812f8ad4bSLinus Torvalds /* 154912f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 155012f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 155112f8ad4bSLinus Torvalds * 155212f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 155312f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 155412f8ad4bSLinus Torvalds */ 15555d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 155631e6b01fSNick Piggin return -ECHILD; 15575a18fff2SAl Viro 1558254cf582SAl Viro *seqp = seq; 15595d0f49c1SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 15604ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 1561209a7fb2SAl Viro if (likely(status > 0)) { 1562daf3761cSTrond Myklebust /* 1563daf3761cSTrond Myklebust * Note: do negative dentry check after revalidation in 1564daf3761cSTrond Myklebust * case that drops it. 1565daf3761cSTrond Myklebust */ 15665d0f49c1SAl Viro if (unlikely(negative)) 1567daf3761cSTrond Myklebust return -ENOENT; 156831e6b01fSNick Piggin path->mnt = mnt; 156931e6b01fSNick Piggin path->dentry = dentry; 1570254cf582SAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 1571e9742b53SAl Viro return 1; 1572209a7fb2SAl Viro } 1573254cf582SAl Viro if (unlazy_walk(nd, dentry, seq)) 15745a18fff2SAl Viro return -ECHILD; 1575209a7fb2SAl Viro if (unlikely(status == -ECHILD)) 1576209a7fb2SAl Viro /* we'd been told to redo it in non-rcu mode */ 1577209a7fb2SAl Viro status = d_revalidate(dentry, nd->flags); 15785a18fff2SAl Viro } else { 1579e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 158081e6f520SAl Viro if (unlikely(!dentry)) 1581e9742b53SAl Viro return 0; 15825d0f49c1SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 15834ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15845d0f49c1SAl Viro } 15855a18fff2SAl Viro if (unlikely(status <= 0)) { 1586e9742b53SAl Viro if (!status) 15875d0f49c1SAl Viro d_invalidate(dentry); 15885a18fff2SAl Viro dput(dentry); 15895a18fff2SAl Viro return status; 15905a18fff2SAl Viro } 1591766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1592766c4cbfSAl Viro dput(dentry); 1593766c4cbfSAl Viro return -ENOENT; 1594766c4cbfSAl Viro } 15955d0f49c1SAl Viro 15961da177e4SLinus Torvalds path->mnt = mnt; 15971da177e4SLinus Torvalds path->dentry = dentry; 1598756daf26SNeilBrown err = follow_managed(path, nd); 1599e9742b53SAl Viro if (likely(err > 0)) 160063afdfc7SDavid Howells *inode = d_backing_inode(path->dentry); 16018402752eSAl Viro return err; 1602697f514dSMiklos Szeredi } 1603697f514dSMiklos Szeredi 1604697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1605e3c13928SAl Viro static struct dentry *lookup_slow(const struct qstr *name, 1606e3c13928SAl Viro struct dentry *dir, 1607e3c13928SAl Viro unsigned int flags) 1608697f514dSMiklos Szeredi { 160994bdd655SAl Viro struct dentry *dentry = ERR_PTR(-ENOENT), *old; 16101936386eSAl Viro struct inode *inode = dir->d_inode; 1611d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 16121936386eSAl Viro 16139902af79SAl Viro inode_lock_shared(inode); 16141936386eSAl Viro /* Don't go there if it's already dead */ 161594bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 161694bdd655SAl Viro goto out; 161794bdd655SAl Viro again: 1618d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 161994bdd655SAl Viro if (IS_ERR(dentry)) 162094bdd655SAl Viro goto out; 162194bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1622949a852eSAl Viro if ((dentry->d_flags & DCACHE_OP_REVALIDATE) && 1623949a852eSAl Viro !(flags & LOOKUP_NO_REVAL)) { 1624949a852eSAl Viro int error = d_revalidate(dentry, flags); 1625949a852eSAl Viro if (unlikely(error <= 0)) { 162694bdd655SAl Viro if (!error) { 1627949a852eSAl Viro d_invalidate(dentry); 1628949a852eSAl Viro dput(dentry); 162994bdd655SAl Viro goto again; 163094bdd655SAl Viro } 163194bdd655SAl Viro dput(dentry); 1632949a852eSAl Viro dentry = ERR_PTR(error); 1633949a852eSAl Viro } 1634949a852eSAl Viro } 163594bdd655SAl Viro } else { 16361936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 163785c7f810SAl Viro d_lookup_done(dentry); 16381936386eSAl Viro if (unlikely(old)) { 16391936386eSAl Viro dput(dentry); 16401936386eSAl Viro dentry = old; 1641949a852eSAl Viro } 1642949a852eSAl Viro } 164394bdd655SAl Viro out: 16449902af79SAl Viro inode_unlock_shared(inode); 1645e3c13928SAl Viro return dentry; 16461da177e4SLinus Torvalds } 16471da177e4SLinus Torvalds 164852094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 164952094c8aSAl Viro { 165052094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16514ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 165252094c8aSAl Viro if (err != -ECHILD) 165352094c8aSAl Viro return err; 16546e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 165552094c8aSAl Viro return -ECHILD; 165652094c8aSAl Viro } 16574ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 165852094c8aSAl Viro } 165952094c8aSAl Viro 16609856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 16619856fa1bSAl Viro { 16629856fa1bSAl Viro if (type == LAST_DOTDOT) { 16639e6697e2SAl Viro if (!nd->root.mnt) 16649e6697e2SAl Viro set_root(nd); 16659856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 166670291aecSAl Viro return follow_dotdot_rcu(nd); 16679856fa1bSAl Viro } else 1668397d425dSEric W. Biederman return follow_dotdot(nd); 16699856fa1bSAl Viro } 16709856fa1bSAl Viro return 0; 16719856fa1bSAl Viro } 16729856fa1bSAl Viro 1673181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1674181548c0SAl Viro struct inode *inode, unsigned seq) 1675d63ff28fSAl Viro { 1676626de996SAl Viro int error; 16771cf2665bSAl Viro struct saved *last; 1678756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1679626de996SAl Viro path_to_nameidata(link, nd); 1680626de996SAl Viro return -ELOOP; 1681626de996SAl Viro } 1682bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1683cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1684cd179f44SAl Viro mntget(link->mnt); 16857973387aSAl Viro } 1686626de996SAl Viro error = nd_alloc_stack(nd); 1687626de996SAl Viro if (unlikely(error)) { 1688bc40aee0SAl Viro if (error == -ECHILD) { 1689ad1633a1SAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 1690ad1633a1SAl Viro drop_links(nd); 1691ad1633a1SAl Viro nd->depth = 0; 1692ad1633a1SAl Viro nd->flags &= ~LOOKUP_RCU; 1693ad1633a1SAl Viro nd->path.mnt = NULL; 1694ad1633a1SAl Viro nd->path.dentry = NULL; 1695ad1633a1SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1696ad1633a1SAl Viro nd->root.mnt = NULL; 1697ad1633a1SAl Viro rcu_read_unlock(); 1698ad1633a1SAl Viro } else if (likely(unlazy_walk(nd, NULL, 0)) == 0) 1699bc40aee0SAl Viro error = nd_alloc_stack(nd); 1700bc40aee0SAl Viro } 1701bc40aee0SAl Viro if (error) { 1702cd179f44SAl Viro path_put(link); 1703626de996SAl Viro return error; 1704626de996SAl Viro } 1705bc40aee0SAl Viro } 1706626de996SAl Viro 1707ab104923SAl Viro last = nd->stack + nd->depth++; 17081cf2665bSAl Viro last->link = *link; 1709fceef393SAl Viro clear_delayed_call(&last->done); 1710fceef393SAl Viro nd->link_inode = inode; 17110450b2d1SAl Viro last->seq = seq; 1712d63ff28fSAl Viro return 1; 1713d63ff28fSAl Viro } 1714d63ff28fSAl Viro 17158f64fb1cSAl Viro enum {WALK_FOLLOW = 1, WALK_MORE = 2}; 171631d66bcdSAl Viro 17173ddcd056SLinus Torvalds /* 17183ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 17193ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 17203ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 17213ddcd056SLinus Torvalds * for the common case. 17223ddcd056SLinus Torvalds */ 17238f64fb1cSAl Viro static inline int step_into(struct nameidata *nd, struct path *path, 17248f64fb1cSAl Viro int flags, struct inode *inode, unsigned seq) 17253ddcd056SLinus Torvalds { 172631d66bcdSAl Viro if (!(flags & WALK_MORE) && nd->depth) 172731d66bcdSAl Viro put_link(nd); 17288f64fb1cSAl Viro if (likely(!d_is_symlink(path->dentry)) || 17298f64fb1cSAl Viro !(flags & WALK_FOLLOW || nd->flags & LOOKUP_FOLLOW)) { 17308f64fb1cSAl Viro /* not a symlink or should not follow */ 17318f64fb1cSAl Viro path_to_nameidata(path, nd); 17328f64fb1cSAl Viro nd->inode = inode; 17338f64fb1cSAl Viro nd->seq = seq; 1734d63ff28fSAl Viro return 0; 17358f64fb1cSAl Viro } 1736a7f77542SAl Viro /* make sure that d_is_symlink above matches inode */ 1737a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 17388f64fb1cSAl Viro if (read_seqcount_retry(&path->dentry->d_seq, seq)) 1739a7f77542SAl Viro return -ECHILD; 1740a7f77542SAl Viro } 17418f64fb1cSAl Viro return pick_link(nd, path, inode, seq); 17423ddcd056SLinus Torvalds } 17433ddcd056SLinus Torvalds 17444693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1745ce57dfc1SAl Viro { 1746caa85634SAl Viro struct path path; 1747ce57dfc1SAl Viro struct inode *inode; 1748254cf582SAl Viro unsigned seq; 1749ce57dfc1SAl Viro int err; 1750ce57dfc1SAl Viro /* 1751ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1752ce57dfc1SAl Viro * to be able to know about the current root directory and 1753ce57dfc1SAl Viro * parent relationships. 1754ce57dfc1SAl Viro */ 17554693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 17564693a547SAl Viro err = handle_dots(nd, nd->last_type); 17571c4ff1a8SAl Viro if (!(flags & WALK_MORE) && nd->depth) 17584693a547SAl Viro put_link(nd); 17594693a547SAl Viro return err; 17604693a547SAl Viro } 1761254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1762e9742b53SAl Viro if (unlikely(err <= 0)) { 1763697f514dSMiklos Szeredi if (err < 0) 1764f0a9ba70SAl Viro return err; 1765e3c13928SAl Viro path.dentry = lookup_slow(&nd->last, nd->path.dentry, 1766e3c13928SAl Viro nd->flags); 1767e3c13928SAl Viro if (IS_ERR(path.dentry)) 1768e3c13928SAl Viro return PTR_ERR(path.dentry); 17697500c38aSAl Viro 1770e3c13928SAl Viro path.mnt = nd->path.mnt; 1771e3c13928SAl Viro err = follow_managed(&path, nd); 1772e3c13928SAl Viro if (unlikely(err < 0)) 1773f0a9ba70SAl Viro return err; 1774697f514dSMiklos Szeredi 17757500c38aSAl Viro if (unlikely(d_is_negative(path.dentry))) { 17767500c38aSAl Viro path_to_nameidata(&path, nd); 17777500c38aSAl Viro return -ENOENT; 17787500c38aSAl Viro } 17797500c38aSAl Viro 1780254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1781d4565649SAl Viro inode = d_backing_inode(path.dentry); 1782766c4cbfSAl Viro } 1783697f514dSMiklos Szeredi 17848f64fb1cSAl Viro return step_into(nd, &path, flags, inode, seq); 1785ce57dfc1SAl Viro } 1786ce57dfc1SAl Viro 17871da177e4SLinus Torvalds /* 1788bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1789bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1790bfcfaa77SLinus Torvalds * 1791bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1792bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1793bfcfaa77SLinus Torvalds * fast. 1794bfcfaa77SLinus Torvalds * 1795bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1796bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1797bfcfaa77SLinus Torvalds * crossing operation. 1798bfcfaa77SLinus Torvalds * 1799bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1800bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1801bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1802bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1803bfcfaa77SLinus Torvalds */ 1804bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1805bfcfaa77SLinus Torvalds 1806f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1807bfcfaa77SLinus Torvalds 1808468a9428SGeorge Spelvin #ifdef HASH_MIX 1809bfcfaa77SLinus Torvalds 1810468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1811468a9428SGeorge Spelvin 1812468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 18132a18da7aSGeorge Spelvin /* 18142a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 18152a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 18162a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 18172a18da7aSGeorge Spelvin * and no temporaries. 18182a18da7aSGeorge Spelvin * 18192a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 18202a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 18212a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 18222a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 18232a18da7aSGeorge Spelvin * 18242a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 18252a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 18262a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 18272a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 18282a18da7aSGeorge Spelvin * 18292a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 18302a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 18312a18da7aSGeorge Spelvin * toggling any given output bit. 18322a18da7aSGeorge Spelvin * 18332a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 18342a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18352a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 18362a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 18372a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 18382a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 18392a18da7aSGeorge Spelvin * Perfect: 8192 258048 18402a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 18412a18da7aSGeorge Spelvin */ 18422a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18432a18da7aSGeorge Spelvin ( x ^= (a), \ 18442a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 18452a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 18462a18da7aSGeorge Spelvin y *= 9 ) 1847bfcfaa77SLinus Torvalds 18480fed3ac8SGeorge Spelvin /* 18492a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 18502a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 18512a18da7aSGeorge Spelvin * work done before the hash value is used. 18520fed3ac8SGeorge Spelvin */ 18532a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18540fed3ac8SGeorge Spelvin { 18552a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 18562a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 18572a18da7aSGeorge Spelvin return y >> 32; 18580fed3ac8SGeorge Spelvin } 18590fed3ac8SGeorge Spelvin 1860bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1861bfcfaa77SLinus Torvalds 18622a18da7aSGeorge Spelvin /* 18632a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 18642a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18652a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 18662a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 18672a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 18682a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 18692a18da7aSGeorge Spelvin * Perfect: 2048 31744 18702a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 18712a18da7aSGeorge Spelvin */ 18722a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18732a18da7aSGeorge Spelvin ( x ^= (a), \ 18742a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 18752a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 18762a18da7aSGeorge Spelvin y *= 9 ) 1877bfcfaa77SLinus Torvalds 18782a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18790fed3ac8SGeorge Spelvin { 18802a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 18812a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 18820fed3ac8SGeorge Spelvin } 18830fed3ac8SGeorge Spelvin 1884bfcfaa77SLinus Torvalds #endif 1885bfcfaa77SLinus Torvalds 18862a18da7aSGeorge Spelvin /* 18872a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 18882a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 18892a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 18902a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 18912a18da7aSGeorge Spelvin * finds the delimiter after the name. 18922a18da7aSGeorge Spelvin */ 18938387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 1894bfcfaa77SLinus Torvalds { 18958387ff25SLinus Torvalds unsigned long a, x = 0, y = (unsigned long)salt; 1896bfcfaa77SLinus Torvalds 1897bfcfaa77SLinus Torvalds for (;;) { 1898fcfd2fbfSGeorge Spelvin if (!len) 1899fcfd2fbfSGeorge Spelvin goto done; 1900e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1901bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1902bfcfaa77SLinus Torvalds break; 19032a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1904bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1905bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1906bfcfaa77SLinus Torvalds } 19072a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 1908bfcfaa77SLinus Torvalds done: 19092a18da7aSGeorge Spelvin return fold_hash(x, y); 1910bfcfaa77SLinus Torvalds } 1911bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1912bfcfaa77SLinus Torvalds 1913fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 19148387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 1915fcfd2fbfSGeorge Spelvin { 19168387ff25SLinus Torvalds unsigned long a = 0, x = 0, y = (unsigned long)salt; 19178387ff25SLinus Torvalds unsigned long adata, mask, len; 1918fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1919fcfd2fbfSGeorge Spelvin 19208387ff25SLinus Torvalds len = 0; 19218387ff25SLinus Torvalds goto inside; 19228387ff25SLinus Torvalds 1923fcfd2fbfSGeorge Spelvin do { 19242a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1925fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 19268387ff25SLinus Torvalds inside: 1927fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 1928fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 1929fcfd2fbfSGeorge Spelvin 1930fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 1931fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 19322a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 1933fcfd2fbfSGeorge Spelvin 19342a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1935fcfd2fbfSGeorge Spelvin } 1936fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 1937fcfd2fbfSGeorge Spelvin 1938bfcfaa77SLinus Torvalds /* 1939bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1940d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1941bfcfaa77SLinus Torvalds */ 19428387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 1943bfcfaa77SLinus Torvalds { 19448387ff25SLinus Torvalds unsigned long a = 0, b, x = 0, y = (unsigned long)salt; 19458387ff25SLinus Torvalds unsigned long adata, bdata, mask, len; 194636126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1947bfcfaa77SLinus Torvalds 19488387ff25SLinus Torvalds len = 0; 19498387ff25SLinus Torvalds goto inside; 19508387ff25SLinus Torvalds 1951bfcfaa77SLinus Torvalds do { 19522a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1953bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 19548387ff25SLinus Torvalds inside: 1955e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 195636126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 195736126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1958bfcfaa77SLinus Torvalds 195936126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 196036126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 196136126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 19622a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 196336126f8fSLinus Torvalds 19642a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1965bfcfaa77SLinus Torvalds } 1966bfcfaa77SLinus Torvalds 19672a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 1968bfcfaa77SLinus Torvalds 1969fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 19708387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 19710145acc2SLinus Torvalds { 19728387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 19730145acc2SLinus Torvalds while (len--) 1974fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 19750145acc2SLinus Torvalds return end_name_hash(hash); 19760145acc2SLinus Torvalds } 1977ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 19780145acc2SLinus Torvalds 1979fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 19808387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 1981fcfd2fbfSGeorge Spelvin { 19828387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 1983fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 1984fcfd2fbfSGeorge Spelvin 1985fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 1986e0ab7af9SGeorge Spelvin while (c) { 1987fcfd2fbfSGeorge Spelvin len++; 1988fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 1989fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 1990e0ab7af9SGeorge Spelvin } 1991fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 1992fcfd2fbfSGeorge Spelvin } 1993f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 1994fcfd2fbfSGeorge Spelvin 19953ddcd056SLinus Torvalds /* 1996200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1997200e9ef7SLinus Torvalds * one character. 1998200e9ef7SLinus Torvalds */ 19998387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2000200e9ef7SLinus Torvalds { 20018387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2002200e9ef7SLinus Torvalds unsigned long len = 0, c; 2003200e9ef7SLinus Torvalds 2004200e9ef7SLinus Torvalds c = (unsigned char)*name; 2005200e9ef7SLinus Torvalds do { 2006200e9ef7SLinus Torvalds len++; 2007200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2008200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2009200e9ef7SLinus Torvalds } while (c && c != '/'); 2010d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2011200e9ef7SLinus Torvalds } 2012200e9ef7SLinus Torvalds 2013bfcfaa77SLinus Torvalds #endif 2014bfcfaa77SLinus Torvalds 2015200e9ef7SLinus Torvalds /* 20161da177e4SLinus Torvalds * Name resolution. 2017ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2018ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 20191da177e4SLinus Torvalds * 2020ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2021ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 20221da177e4SLinus Torvalds */ 20236de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 20241da177e4SLinus Torvalds { 20251da177e4SLinus Torvalds int err; 20261da177e4SLinus Torvalds 20271da177e4SLinus Torvalds while (*name=='/') 20281da177e4SLinus Torvalds name++; 20291da177e4SLinus Torvalds if (!*name) 20309e18f10aSAl Viro return 0; 20311da177e4SLinus Torvalds 20321da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 20331da177e4SLinus Torvalds for(;;) { 2034d6bb3e90SLinus Torvalds u64 hash_len; 2035fe479a58SAl Viro int type; 20361da177e4SLinus Torvalds 203752094c8aSAl Viro err = may_lookup(nd); 20381da177e4SLinus Torvalds if (err) 20393595e234SAl Viro return err; 20401da177e4SLinus Torvalds 20418387ff25SLinus Torvalds hash_len = hash_name(nd->path.dentry, name); 20421da177e4SLinus Torvalds 2043fe479a58SAl Viro type = LAST_NORM; 2044d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2045fe479a58SAl Viro case 2: 2046200e9ef7SLinus Torvalds if (name[1] == '.') { 2047fe479a58SAl Viro type = LAST_DOTDOT; 204816c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 204916c2cd71SAl Viro } 2050fe479a58SAl Viro break; 2051fe479a58SAl Viro case 1: 2052fe479a58SAl Viro type = LAST_DOT; 2053fe479a58SAl Viro } 20545a202bcdSAl Viro if (likely(type == LAST_NORM)) { 20555a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 205616c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 20575a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2058a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2059da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 20605a202bcdSAl Viro if (err < 0) 20613595e234SAl Viro return err; 2062d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2063d6bb3e90SLinus Torvalds name = this.name; 20645a202bcdSAl Viro } 20655a202bcdSAl Viro } 2066fe479a58SAl Viro 2067d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2068d6bb3e90SLinus Torvalds nd->last.name = name; 20695f4a6a69SAl Viro nd->last_type = type; 20705f4a6a69SAl Viro 2071d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2072d6bb3e90SLinus Torvalds if (!*name) 2073bdf6cbf1SAl Viro goto OK; 2074200e9ef7SLinus Torvalds /* 2075200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2076200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2077200e9ef7SLinus Torvalds */ 2078200e9ef7SLinus Torvalds do { 2079d6bb3e90SLinus Torvalds name++; 2080d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 20818620c238SAl Viro if (unlikely(!*name)) { 20828620c238SAl Viro OK: 2083368ee9baSAl Viro /* pathname body, done */ 20848620c238SAl Viro if (!nd->depth) 20858620c238SAl Viro return 0; 20868620c238SAl Viro name = nd->stack[nd->depth - 1].name; 2087368ee9baSAl Viro /* trailing symlink, done */ 20888620c238SAl Viro if (!name) 20898620c238SAl Viro return 0; 20908620c238SAl Viro /* last component of nested symlink */ 20918f64fb1cSAl Viro err = walk_component(nd, WALK_FOLLOW); 20921c4ff1a8SAl Viro } else { 20931c4ff1a8SAl Viro /* not the last component */ 20948f64fb1cSAl Viro err = walk_component(nd, WALK_FOLLOW | WALK_MORE); 20958620c238SAl Viro } 2096ce57dfc1SAl Viro if (err < 0) 20973595e234SAl Viro return err; 2098fe479a58SAl Viro 2099ce57dfc1SAl Viro if (err) { 2100626de996SAl Viro const char *s = get_link(nd); 21015a460275SAl Viro 2102a1c83681SViresh Kumar if (IS_ERR(s)) 21033595e234SAl Viro return PTR_ERR(s); 2104172a39a0SAl Viro err = 0; 210512b09578SAl Viro if (unlikely(!s)) { 210612b09578SAl Viro /* jumped */ 2107b9ff4429SAl Viro put_link(nd); 210812b09578SAl Viro } else { 2109071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 211032cd7468SAl Viro name = s; 21119e18f10aSAl Viro continue; 211248c8b0c5SAl Viro } 211331e6b01fSNick Piggin } 211497242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 211597242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 211697242f99SAl Viro if (unlazy_walk(nd, NULL, 0)) 211797242f99SAl Viro return -ECHILD; 211897242f99SAl Viro } 21193595e234SAl Viro return -ENOTDIR; 21205f4a6a69SAl Viro } 2121ce57dfc1SAl Viro } 212297242f99SAl Viro } 21231da177e4SLinus Torvalds 2124c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 212531e6b01fSNick Piggin { 212631e6b01fSNick Piggin int retval = 0; 2127c8a53ee5SAl Viro const char *s = nd->name->name; 212831e6b01fSNick Piggin 212931e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 2130980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 213131e6b01fSNick Piggin nd->depth = 0; 21325b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2133b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2134b18825a7SDavid Howells struct inode *inode = root->d_inode; 2135fd2f7cb5SAl Viro if (*s) { 213644b1d530SMiklos Szeredi if (!d_can_lookup(root)) 2137368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 21385b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 21395b6ca027SAl Viro if (retval) 2140368ee9baSAl Viro return ERR_PTR(retval); 214173d049a4SAl Viro } 21425b6ca027SAl Viro nd->path = nd->root; 21435b6ca027SAl Viro nd->inode = inode; 21445b6ca027SAl Viro if (flags & LOOKUP_RCU) { 21458b61e74fSAl Viro rcu_read_lock(); 21465b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 21478f47a016SAl Viro nd->root_seq = nd->seq; 214848a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 21495b6ca027SAl Viro } else { 21505b6ca027SAl Viro path_get(&nd->path); 21515b6ca027SAl Viro } 2152368ee9baSAl Viro return s; 21535b6ca027SAl Viro } 21545b6ca027SAl Viro 215531e6b01fSNick Piggin nd->root.mnt = NULL; 2156248fb5b9SAl Viro nd->path.mnt = NULL; 2157248fb5b9SAl Viro nd->path.dentry = NULL; 215831e6b01fSNick Piggin 215948a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 2160fd2f7cb5SAl Viro if (*s == '/') { 21619e6697e2SAl Viro if (flags & LOOKUP_RCU) 21628b61e74fSAl Viro rcu_read_lock(); 2163e41f7d4eSAl Viro set_root(nd); 2164248fb5b9SAl Viro if (likely(!nd_jump_root(nd))) 2165ef55d917SAl Viro return s; 2166ef55d917SAl Viro nd->root.mnt = NULL; 2167ef55d917SAl Viro rcu_read_unlock(); 2168ef55d917SAl Viro return ERR_PTR(-ECHILD); 2169c8a53ee5SAl Viro } else if (nd->dfd == AT_FDCWD) { 2170e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 217131e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2172c28cc364SNick Piggin unsigned seq; 217331e6b01fSNick Piggin 21748b61e74fSAl Viro rcu_read_lock(); 217531e6b01fSNick Piggin 2176c28cc364SNick Piggin do { 2177c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 217831e6b01fSNick Piggin nd->path = fs->pwd; 2179ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2180c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2181c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2182e41f7d4eSAl Viro } else { 2183e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2184ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2185e41f7d4eSAl Viro } 2186ef55d917SAl Viro return s; 218731e6b01fSNick Piggin } else { 2188582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2189c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 219031e6b01fSNick Piggin struct dentry *dentry; 219131e6b01fSNick Piggin 21922903ff01SAl Viro if (!f.file) 2193368ee9baSAl Viro return ERR_PTR(-EBADF); 219431e6b01fSNick Piggin 21952903ff01SAl Viro dentry = f.file->f_path.dentry; 219631e6b01fSNick Piggin 2197fd2f7cb5SAl Viro if (*s) { 219844b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 21992903ff01SAl Viro fdput(f); 2200368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2201f52e0c11SAl Viro } 22022903ff01SAl Viro } 22032903ff01SAl Viro 22042903ff01SAl Viro nd->path = f.file->f_path; 2205e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 22068b61e74fSAl Viro rcu_read_lock(); 220734a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 220834a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22095590ff0dSUlrich Drepper } else { 22102903ff01SAl Viro path_get(&nd->path); 221134a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 22121da177e4SLinus Torvalds } 221334a26b99SAl Viro fdput(f); 2214368ee9baSAl Viro return s; 2215e41f7d4eSAl Viro } 22169b4a9b14SAl Viro } 22179b4a9b14SAl Viro 22183bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 221995fa25d9SAl Viro { 222095fa25d9SAl Viro const char *s; 2221fec2fa24SAl Viro int error = may_follow_link(nd); 2222deb106c6SAl Viro if (unlikely(error)) 22233bdba28bSAl Viro return ERR_PTR(error); 222495fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2225fab51e8aSAl Viro nd->stack[0].name = NULL; 22263b2e7f75SAl Viro s = get_link(nd); 2227deb106c6SAl Viro return s ? s : ""; 222895fa25d9SAl Viro } 222995fa25d9SAl Viro 2230caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2231bd92d7feSAl Viro { 2232bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2233bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2234bd92d7feSAl Viro 2235bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 22361c4ff1a8SAl Viro return walk_component(nd, 0); 2237bd92d7feSAl Viro } 2238bd92d7feSAl Viro 22399b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2240c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 22419b4a9b14SAl Viro { 2242c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2243bd92d7feSAl Viro int err; 224431e6b01fSNick Piggin 2245368ee9baSAl Viro if (IS_ERR(s)) 2246368ee9baSAl Viro return PTR_ERR(s); 22473bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 22483bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 22493bdba28bSAl Viro s = trailing_symlink(nd); 22503bdba28bSAl Viro if (IS_ERR(s)) { 22513bdba28bSAl Viro err = PTR_ERR(s); 22526d7b5aaeSAl Viro break; 2253bd92d7feSAl Viro } 2254bd92d7feSAl Viro } 22559f1fafeeSAl Viro if (!err) 22569f1fafeeSAl Viro err = complete_walk(nd); 2257bd92d7feSAl Viro 2258deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2259deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2260bd23a539SAl Viro err = -ENOTDIR; 2261625b6d10SAl Viro if (!err) { 2262625b6d10SAl Viro *path = nd->path; 2263625b6d10SAl Viro nd->path.mnt = NULL; 2264625b6d10SAl Viro nd->path.dentry = NULL; 2265625b6d10SAl Viro } 2266deb106c6SAl Viro terminate_walk(nd); 2267bd92d7feSAl Viro return err; 226831e6b01fSNick Piggin } 226931e6b01fSNick Piggin 2270625b6d10SAl Viro static int filename_lookup(int dfd, struct filename *name, unsigned flags, 22719ad1aaa6SAl Viro struct path *path, struct path *root) 2272873f1eedSJeff Layton { 2273894bc8c4SAl Viro int retval; 22749883d185SAl Viro struct nameidata nd; 2275abc9f5beSAl Viro if (IS_ERR(name)) 2276abc9f5beSAl Viro return PTR_ERR(name); 22779ad1aaa6SAl Viro if (unlikely(root)) { 22789ad1aaa6SAl Viro nd.root = *root; 22799ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 22809ad1aaa6SAl Viro } 22819883d185SAl Viro set_nameidata(&nd, dfd, name); 2282c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2283873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2284c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2285873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2286c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2287873f1eedSJeff Layton 2288873f1eedSJeff Layton if (likely(!retval)) 2289625b6d10SAl Viro audit_inode(name, path->dentry, flags & LOOKUP_PARENT); 22909883d185SAl Viro restore_nameidata(); 2291e4bd1c1aSAl Viro putname(name); 2292873f1eedSJeff Layton return retval; 2293873f1eedSJeff Layton } 2294873f1eedSJeff Layton 22958bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2296c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2297391172c4SAl Viro struct path *parent) 22988bcb77faSAl Viro { 2299c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2300368ee9baSAl Viro int err; 2301368ee9baSAl Viro if (IS_ERR(s)) 2302368ee9baSAl Viro return PTR_ERR(s); 2303368ee9baSAl Viro err = link_path_walk(s, nd); 23048bcb77faSAl Viro if (!err) 23058bcb77faSAl Viro err = complete_walk(nd); 2306391172c4SAl Viro if (!err) { 2307391172c4SAl Viro *parent = nd->path; 2308391172c4SAl Viro nd->path.mnt = NULL; 2309391172c4SAl Viro nd->path.dentry = NULL; 2310391172c4SAl Viro } 2311deb106c6SAl Viro terminate_walk(nd); 23128bcb77faSAl Viro return err; 23138bcb77faSAl Viro } 23148bcb77faSAl Viro 23155c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2316391172c4SAl Viro unsigned int flags, struct path *parent, 2317391172c4SAl Viro struct qstr *last, int *type) 23188bcb77faSAl Viro { 23198bcb77faSAl Viro int retval; 23209883d185SAl Viro struct nameidata nd; 23218bcb77faSAl Viro 23225c31b6ceSAl Viro if (IS_ERR(name)) 23235c31b6ceSAl Viro return name; 23249883d185SAl Viro set_nameidata(&nd, dfd, name); 2325c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 23268bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2327c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 23288bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2329c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2330391172c4SAl Viro if (likely(!retval)) { 2331391172c4SAl Viro *last = nd.last; 2332391172c4SAl Viro *type = nd.last_type; 2333391172c4SAl Viro audit_inode(name, parent->dentry, LOOKUP_PARENT); 23345c31b6ceSAl Viro } else { 23355c31b6ceSAl Viro putname(name); 23365c31b6ceSAl Viro name = ERR_PTR(retval); 2337391172c4SAl Viro } 23389883d185SAl Viro restore_nameidata(); 23395c31b6ceSAl Viro return name; 23408bcb77faSAl Viro } 23418bcb77faSAl Viro 234279714f72SAl Viro /* does lookup, returns the object with parent locked */ 234379714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 23445590ff0dSUlrich Drepper { 23455c31b6ceSAl Viro struct filename *filename; 23465c31b6ceSAl Viro struct dentry *d; 2347391172c4SAl Viro struct qstr last; 2348391172c4SAl Viro int type; 234951689104SPaul Moore 23505c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 23515c31b6ceSAl Viro &last, &type); 235251689104SPaul Moore if (IS_ERR(filename)) 235351689104SPaul Moore return ERR_CAST(filename); 23545c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2355391172c4SAl Viro path_put(path); 23565c31b6ceSAl Viro putname(filename); 23575c31b6ceSAl Viro return ERR_PTR(-EINVAL); 235879714f72SAl Viro } 23595955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2360391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 236179714f72SAl Viro if (IS_ERR(d)) { 23625955102cSAl Viro inode_unlock(path->dentry->d_inode); 2363391172c4SAl Viro path_put(path); 236479714f72SAl Viro } 236551689104SPaul Moore putname(filename); 236679714f72SAl Viro return d; 23675590ff0dSUlrich Drepper } 23685590ff0dSUlrich Drepper 2369d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2370d1811465SAl Viro { 2371abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2372abc9f5beSAl Viro flags, path, NULL); 2373d1811465SAl Viro } 23744d359507SAl Viro EXPORT_SYMBOL(kern_path); 2375d1811465SAl Viro 237616f18200SJosef 'Jeff' Sipek /** 237716f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 237816f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 237916f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 238016f18200SJosef 'Jeff' Sipek * @name: pointer to file name 238116f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2382e0a01249SAl Viro * @path: pointer to struct path to fill 238316f18200SJosef 'Jeff' Sipek */ 238416f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 238516f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2386e0a01249SAl Viro struct path *path) 238716f18200SJosef 'Jeff' Sipek { 23889ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 23899ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2390abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2391abc9f5beSAl Viro flags , path, &root); 239216f18200SJosef 'Jeff' Sipek } 23934d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 239416f18200SJosef 'Jeff' Sipek 2395eead1911SChristoph Hellwig /** 2396a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2397eead1911SChristoph Hellwig * @name: pathname component to lookup 2398eead1911SChristoph Hellwig * @base: base directory to lookup from 2399eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2400eead1911SChristoph Hellwig * 2401a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 24029e7543e9SAl Viro * not be called by generic code. 2403bbddca8eSNeilBrown * 2404bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2405eead1911SChristoph Hellwig */ 2406057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2407057f6c01SJames Morris { 2408057f6c01SJames Morris struct qstr this; 24096a96ba54SAl Viro unsigned int c; 2410cda309deSMiklos Szeredi int err; 2411057f6c01SJames Morris 24125955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 24132f9092e1SDavid Woodhouse 24146a96ba54SAl Viro this.name = name; 24156a96ba54SAl Viro this.len = len; 24168387ff25SLinus Torvalds this.hash = full_name_hash(base, name, len); 24176a96ba54SAl Viro if (!len) 24186a96ba54SAl Viro return ERR_PTR(-EACCES); 24196a96ba54SAl Viro 242021d8a15aSAl Viro if (unlikely(name[0] == '.')) { 242121d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 242221d8a15aSAl Viro return ERR_PTR(-EACCES); 242321d8a15aSAl Viro } 242421d8a15aSAl Viro 24256a96ba54SAl Viro while (len--) { 24266a96ba54SAl Viro c = *(const unsigned char *)name++; 24276a96ba54SAl Viro if (c == '/' || c == '\0') 24286a96ba54SAl Viro return ERR_PTR(-EACCES); 24296a96ba54SAl Viro } 24305a202bcdSAl Viro /* 24315a202bcdSAl Viro * See if the low-level filesystem might want 24325a202bcdSAl Viro * to use its own hash.. 24335a202bcdSAl Viro */ 24345a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2435da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 24365a202bcdSAl Viro if (err < 0) 24375a202bcdSAl Viro return ERR_PTR(err); 24385a202bcdSAl Viro } 2439eead1911SChristoph Hellwig 2440cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2441cda309deSMiklos Szeredi if (err) 2442cda309deSMiklos Szeredi return ERR_PTR(err); 2443cda309deSMiklos Szeredi 244472bd866aSAl Viro return __lookup_hash(&this, base, 0); 2445057f6c01SJames Morris } 24464d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2447057f6c01SJames Morris 2448bbddca8eSNeilBrown /** 2449bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2450bbddca8eSNeilBrown * @name: pathname component to lookup 2451bbddca8eSNeilBrown * @base: base directory to lookup from 2452bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2453bbddca8eSNeilBrown * 2454bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2455bbddca8eSNeilBrown * not be called by generic code. 2456bbddca8eSNeilBrown * 2457bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2458bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2459bbddca8eSNeilBrown */ 2460bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2461bbddca8eSNeilBrown struct dentry *base, int len) 2462bbddca8eSNeilBrown { 2463bbddca8eSNeilBrown struct qstr this; 2464bbddca8eSNeilBrown unsigned int c; 2465bbddca8eSNeilBrown int err; 246620d00ee8SLinus Torvalds struct dentry *ret; 2467bbddca8eSNeilBrown 2468bbddca8eSNeilBrown this.name = name; 2469bbddca8eSNeilBrown this.len = len; 24708387ff25SLinus Torvalds this.hash = full_name_hash(base, name, len); 2471bbddca8eSNeilBrown if (!len) 2472bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2473bbddca8eSNeilBrown 2474bbddca8eSNeilBrown if (unlikely(name[0] == '.')) { 2475bbddca8eSNeilBrown if (len < 2 || (len == 2 && name[1] == '.')) 2476bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2477bbddca8eSNeilBrown } 2478bbddca8eSNeilBrown 2479bbddca8eSNeilBrown while (len--) { 2480bbddca8eSNeilBrown c = *(const unsigned char *)name++; 2481bbddca8eSNeilBrown if (c == '/' || c == '\0') 2482bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2483bbddca8eSNeilBrown } 2484bbddca8eSNeilBrown /* 2485bbddca8eSNeilBrown * See if the low-level filesystem might want 2486bbddca8eSNeilBrown * to use its own hash.. 2487bbddca8eSNeilBrown */ 2488bbddca8eSNeilBrown if (base->d_flags & DCACHE_OP_HASH) { 2489bbddca8eSNeilBrown int err = base->d_op->d_hash(base, &this); 2490bbddca8eSNeilBrown if (err < 0) 2491bbddca8eSNeilBrown return ERR_PTR(err); 2492bbddca8eSNeilBrown } 2493bbddca8eSNeilBrown 2494bbddca8eSNeilBrown err = inode_permission(base->d_inode, MAY_EXEC); 2495bbddca8eSNeilBrown if (err) 2496bbddca8eSNeilBrown return ERR_PTR(err); 2497bbddca8eSNeilBrown 249820d00ee8SLinus Torvalds ret = lookup_dcache(&this, base, 0); 249920d00ee8SLinus Torvalds if (!ret) 250020d00ee8SLinus Torvalds ret = lookup_slow(&this, base, 0); 250120d00ee8SLinus Torvalds return ret; 2502bbddca8eSNeilBrown } 2503bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2504bbddca8eSNeilBrown 2505eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2506eedf265aSEric W. Biederman int path_pts(struct path *path) 2507eedf265aSEric W. Biederman { 2508eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2509eedf265aSEric W. Biederman * the input path. 2510eedf265aSEric W. Biederman */ 2511eedf265aSEric W. Biederman struct dentry *child, *parent; 2512eedf265aSEric W. Biederman struct qstr this; 2513eedf265aSEric W. Biederman int ret; 2514eedf265aSEric W. Biederman 2515eedf265aSEric W. Biederman ret = path_parent_directory(path); 2516eedf265aSEric W. Biederman if (ret) 2517eedf265aSEric W. Biederman return ret; 2518eedf265aSEric W. Biederman 2519eedf265aSEric W. Biederman parent = path->dentry; 2520eedf265aSEric W. Biederman this.name = "pts"; 2521eedf265aSEric W. Biederman this.len = 3; 2522eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2523eedf265aSEric W. Biederman if (!child) 2524eedf265aSEric W. Biederman return -ENOENT; 2525eedf265aSEric W. Biederman 2526eedf265aSEric W. Biederman path->dentry = child; 2527eedf265aSEric W. Biederman dput(parent); 2528eedf265aSEric W. Biederman follow_mount(path); 2529eedf265aSEric W. Biederman return 0; 2530eedf265aSEric W. Biederman } 2531eedf265aSEric W. Biederman #endif 2532eedf265aSEric W. Biederman 25331fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 25341fa1e7f6SAndy Whitcroft struct path *path, int *empty) 25351da177e4SLinus Torvalds { 2536abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2537abc9f5beSAl Viro flags, path, NULL); 25381da177e4SLinus Torvalds } 2539b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 25401fa1e7f6SAndy Whitcroft 25418033426eSJeff Layton /** 2542197df04cSAl Viro * mountpoint_last - look up last component for umount 25438033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 25448033426eSJeff Layton * 25458033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 25468033426eSJeff Layton * need to resolve the path without doing any revalidation. 25478033426eSJeff Layton * 25488033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 25498033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 25508033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 25518033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 25528033426eSJeff Layton * bogus and it doesn't exist. 25538033426eSJeff Layton * 25548033426eSJeff Layton * Returns: 25558033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 2556ba8f4613SAl Viro * lookup found a negative dentry. 25578033426eSJeff Layton * 2558ba8f4613SAl Viro * 0: if we successfully resolved nd->last and found it to not to be a 2559ba8f4613SAl Viro * symlink that needs to be followed. 25608033426eSJeff Layton * 25618033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 2562ba8f4613SAl Viro * that needs to be followed. 25638033426eSJeff Layton */ 25648033426eSJeff Layton static int 2565ba8f4613SAl Viro mountpoint_last(struct nameidata *nd) 25668033426eSJeff Layton { 25678033426eSJeff Layton int error = 0; 25688033426eSJeff Layton struct dentry *dir = nd->path.dentry; 2569ba8f4613SAl Viro struct path path; 25708033426eSJeff Layton 257135759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 257235759521SAl Viro if (nd->flags & LOOKUP_RCU) { 25736e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 2574deb106c6SAl Viro return -ECHILD; 25758033426eSJeff Layton } 25768033426eSJeff Layton 25778033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 25788033426eSJeff Layton 25798033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 25808033426eSJeff Layton error = handle_dots(nd, nd->last_type); 258135759521SAl Viro if (error) 2582deb106c6SAl Viro return error; 2583ba8f4613SAl Viro path.dentry = dget(nd->path.dentry); 2584949a852eSAl Viro } else { 2585ba8f4613SAl Viro path.dentry = d_lookup(dir, &nd->last); 2586ba8f4613SAl Viro if (!path.dentry) { 25878033426eSJeff Layton /* 2588949a852eSAl Viro * No cached dentry. Mounted dentries are pinned in the 2589949a852eSAl Viro * cache, so that means that this dentry is probably 2590949a852eSAl Viro * a symlink or the path doesn't actually point 2591949a852eSAl Viro * to a mounted dentry. 25928033426eSJeff Layton */ 2593ba8f4613SAl Viro path.dentry = lookup_slow(&nd->last, dir, 2594949a852eSAl Viro nd->flags | LOOKUP_NO_REVAL); 2595ba8f4613SAl Viro if (IS_ERR(path.dentry)) 2596ba8f4613SAl Viro return PTR_ERR(path.dentry); 25978033426eSJeff Layton } 2598bcceeebaSDave Jones } 2599ba8f4613SAl Viro if (d_is_negative(path.dentry)) { 2600ba8f4613SAl Viro dput(path.dentry); 2601deb106c6SAl Viro return -ENOENT; 260235759521SAl Viro } 2603ba8f4613SAl Viro path.mnt = nd->path.mnt; 26048f64fb1cSAl Viro return step_into(nd, &path, 0, d_backing_inode(path.dentry), 0); 26058033426eSJeff Layton } 26068033426eSJeff Layton 26078033426eSJeff Layton /** 2608197df04cSAl Viro * path_mountpoint - look up a path to be umounted 26092a78b857SMasanari Iida * @nd: lookup context 26108033426eSJeff Layton * @flags: lookup flags 2611c8a53ee5SAl Viro * @path: pointer to container for result 26128033426eSJeff Layton * 26138033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2614606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 26158033426eSJeff Layton */ 26168033426eSJeff Layton static int 2617c8a53ee5SAl Viro path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) 26188033426eSJeff Layton { 2619c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2620368ee9baSAl Viro int err; 2621368ee9baSAl Viro if (IS_ERR(s)) 2622368ee9baSAl Viro return PTR_ERR(s); 26233bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 2624ba8f4613SAl Viro (err = mountpoint_last(nd)) > 0) { 26253bdba28bSAl Viro s = trailing_symlink(nd); 26263bdba28bSAl Viro if (IS_ERR(s)) { 26273bdba28bSAl Viro err = PTR_ERR(s); 26288033426eSJeff Layton break; 26298033426eSJeff Layton } 26303bdba28bSAl Viro } 2631ba8f4613SAl Viro if (!err) { 2632ba8f4613SAl Viro *path = nd->path; 2633ba8f4613SAl Viro nd->path.mnt = NULL; 2634ba8f4613SAl Viro nd->path.dentry = NULL; 2635ba8f4613SAl Viro follow_mount(path); 2636ba8f4613SAl Viro } 2637deb106c6SAl Viro terminate_walk(nd); 26388033426eSJeff Layton return err; 26398033426eSJeff Layton } 26408033426eSJeff Layton 26412d864651SAl Viro static int 2642668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 26432d864651SAl Viro unsigned int flags) 26442d864651SAl Viro { 26459883d185SAl Viro struct nameidata nd; 2646cbaab2dbSAl Viro int error; 2647668696dcSAl Viro if (IS_ERR(name)) 2648668696dcSAl Viro return PTR_ERR(name); 26499883d185SAl Viro set_nameidata(&nd, dfd, name); 2650c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); 26512d864651SAl Viro if (unlikely(error == -ECHILD)) 2652c8a53ee5SAl Viro error = path_mountpoint(&nd, flags, path); 26532d864651SAl Viro if (unlikely(error == -ESTALE)) 2654c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); 26552d864651SAl Viro if (likely(!error)) 2656668696dcSAl Viro audit_inode(name, path->dentry, 0); 26579883d185SAl Viro restore_nameidata(); 2658668696dcSAl Viro putname(name); 26592d864651SAl Viro return error; 26602d864651SAl Viro } 26612d864651SAl Viro 26628033426eSJeff Layton /** 2663197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 26648033426eSJeff Layton * @dfd: directory file descriptor 26658033426eSJeff Layton * @name: pathname from userland 26668033426eSJeff Layton * @flags: lookup flags 26678033426eSJeff Layton * @path: pointer to container to hold result 26688033426eSJeff Layton * 26698033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 26708033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 26718033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 26728033426eSJeff Layton * and avoid revalidating the last component. 26738033426eSJeff Layton * 26748033426eSJeff Layton * Returns 0 and populates "path" on success. 26758033426eSJeff Layton */ 26768033426eSJeff Layton int 2677197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 26788033426eSJeff Layton struct path *path) 26798033426eSJeff Layton { 2680cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 26818033426eSJeff Layton } 26828033426eSJeff Layton 26832d864651SAl Viro int 26842d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 26852d864651SAl Viro unsigned int flags) 26862d864651SAl Viro { 2687cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 26882d864651SAl Viro } 26892d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 26902d864651SAl Viro 2691cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 26921da177e4SLinus Torvalds { 26938e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2694da9592edSDavid Howells 26958e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 26961da177e4SLinus Torvalds return 0; 26978e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 26981da177e4SLinus Torvalds return 0; 269923adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 27001da177e4SLinus Torvalds } 2701cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 27021da177e4SLinus Torvalds 27031da177e4SLinus Torvalds /* 27041da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 27051da177e4SLinus Torvalds * whether the type of victim is right. 27061da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 27071da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 27081da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 27091da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 27101da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 27111da177e4SLinus Torvalds * a. be owner of dir, or 27121da177e4SLinus Torvalds * b. be owner of victim, or 27131da177e4SLinus Torvalds * c. have CAP_FOWNER capability 27141da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 27151da177e4SLinus Torvalds * links pointing to it. 27160bd23d09SEric W. Biederman * 7. If the victim has an unknown uid or gid we can't change the inode. 27170bd23d09SEric W. Biederman * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. 27180bd23d09SEric W. Biederman * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. 27190bd23d09SEric W. Biederman * 10. We can't remove a root or mountpoint. 27200bd23d09SEric W. Biederman * 11. We don't allow removal of NFS sillyrenamed files; it's handled by 27211da177e4SLinus Torvalds * nfs_async_unlink(). 27221da177e4SLinus Torvalds */ 2723b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 27241da177e4SLinus Torvalds { 272563afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 27261da177e4SLinus Torvalds int error; 27271da177e4SLinus Torvalds 2728b18825a7SDavid Howells if (d_is_negative(victim)) 27291da177e4SLinus Torvalds return -ENOENT; 2730b18825a7SDavid Howells BUG_ON(!inode); 27311da177e4SLinus Torvalds 27321da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 27334fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 27341da177e4SLinus Torvalds 2735f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 27361da177e4SLinus Torvalds if (error) 27371da177e4SLinus Torvalds return error; 27381da177e4SLinus Torvalds if (IS_APPEND(dir)) 27391da177e4SLinus Torvalds return -EPERM; 2740b18825a7SDavid Howells 2741b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 27420bd23d09SEric W. Biederman IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) 27431da177e4SLinus Torvalds return -EPERM; 27441da177e4SLinus Torvalds if (isdir) { 274544b1d530SMiklos Szeredi if (!d_is_dir(victim)) 27461da177e4SLinus Torvalds return -ENOTDIR; 27471da177e4SLinus Torvalds if (IS_ROOT(victim)) 27481da177e4SLinus Torvalds return -EBUSY; 274944b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 27501da177e4SLinus Torvalds return -EISDIR; 27511da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27521da177e4SLinus Torvalds return -ENOENT; 27531da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 27541da177e4SLinus Torvalds return -EBUSY; 27551da177e4SLinus Torvalds return 0; 27561da177e4SLinus Torvalds } 27571da177e4SLinus Torvalds 27581da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 27591da177e4SLinus Torvalds * dir. 27601da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 27611da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 27621da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 2763036d5236SEric W. Biederman * 3. We can't do it if the fs can't represent the fsuid or fsgid. 2764036d5236SEric W. Biederman * 4. We should have write and exec permissions on dir 2765036d5236SEric W. Biederman * 5. We can't do it if dir is immutable (done in permission()) 27661da177e4SLinus Torvalds */ 2767a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 27681da177e4SLinus Torvalds { 2769036d5236SEric W. Biederman struct user_namespace *s_user_ns; 277014e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 27711da177e4SLinus Torvalds if (child->d_inode) 27721da177e4SLinus Torvalds return -EEXIST; 27731da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27741da177e4SLinus Torvalds return -ENOENT; 2775036d5236SEric W. Biederman s_user_ns = dir->i_sb->s_user_ns; 2776036d5236SEric W. Biederman if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 2777036d5236SEric W. Biederman !kgid_has_mapping(s_user_ns, current_fsgid())) 2778036d5236SEric W. Biederman return -EOVERFLOW; 2779f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 27801da177e4SLinus Torvalds } 27811da177e4SLinus Torvalds 27821da177e4SLinus Torvalds /* 27831da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 27841da177e4SLinus Torvalds */ 27851da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 27861da177e4SLinus Torvalds { 27871da177e4SLinus Torvalds struct dentry *p; 27881da177e4SLinus Torvalds 27891da177e4SLinus Torvalds if (p1 == p2) { 27905955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27911da177e4SLinus Torvalds return NULL; 27921da177e4SLinus Torvalds } 27931da177e4SLinus Torvalds 2794fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 27951da177e4SLinus Torvalds 2796e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2797e2761a11SOGAWA Hirofumi if (p) { 27985955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 27995955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 28001da177e4SLinus Torvalds return p; 28011da177e4SLinus Torvalds } 28021da177e4SLinus Torvalds 2803e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2804e2761a11SOGAWA Hirofumi if (p) { 28055955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28065955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 28071da177e4SLinus Torvalds return p; 28081da177e4SLinus Torvalds } 28091da177e4SLinus Torvalds 28105955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28115955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 28121da177e4SLinus Torvalds return NULL; 28131da177e4SLinus Torvalds } 28144d359507SAl Viro EXPORT_SYMBOL(lock_rename); 28151da177e4SLinus Torvalds 28161da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 28171da177e4SLinus Torvalds { 28185955102cSAl Viro inode_unlock(p1->d_inode); 28191da177e4SLinus Torvalds if (p1 != p2) { 28205955102cSAl Viro inode_unlock(p2->d_inode); 2821fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 28221da177e4SLinus Torvalds } 28231da177e4SLinus Torvalds } 28244d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 28251da177e4SLinus Torvalds 28264acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2827312b63fbSAl Viro bool want_excl) 28281da177e4SLinus Torvalds { 2829a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28301da177e4SLinus Torvalds if (error) 28311da177e4SLinus Torvalds return error; 28321da177e4SLinus Torvalds 2833acfa4380SAl Viro if (!dir->i_op->create) 28341da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 28351da177e4SLinus Torvalds mode &= S_IALLUGO; 28361da177e4SLinus Torvalds mode |= S_IFREG; 28371da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 28381da177e4SLinus Torvalds if (error) 28391da177e4SLinus Torvalds return error; 2840312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2841a74574aaSStephen Smalley if (!error) 2842f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28431da177e4SLinus Torvalds return error; 28441da177e4SLinus Torvalds } 28454d359507SAl Viro EXPORT_SYMBOL(vfs_create); 28461da177e4SLinus Torvalds 2847a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 2848a2982cc9SEric W. Biederman { 2849a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 2850a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 2851a2982cc9SEric W. Biederman } 2852a2982cc9SEric W. Biederman 2853f0bb5aafSAl Viro static int may_open(const struct path *path, int acc_mode, int flag) 28541da177e4SLinus Torvalds { 28553fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 28561da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 28571da177e4SLinus Torvalds int error; 28581da177e4SLinus Torvalds 28591da177e4SLinus Torvalds if (!inode) 28601da177e4SLinus Torvalds return -ENOENT; 28611da177e4SLinus Torvalds 2862c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2863c8fe8f30SChristoph Hellwig case S_IFLNK: 28641da177e4SLinus Torvalds return -ELOOP; 2865c8fe8f30SChristoph Hellwig case S_IFDIR: 2866c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 28671da177e4SLinus Torvalds return -EISDIR; 2868c8fe8f30SChristoph Hellwig break; 2869c8fe8f30SChristoph Hellwig case S_IFBLK: 2870c8fe8f30SChristoph Hellwig case S_IFCHR: 2871a2982cc9SEric W. Biederman if (!may_open_dev(path)) 28721da177e4SLinus Torvalds return -EACCES; 2873c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2874c8fe8f30SChristoph Hellwig case S_IFIFO: 2875c8fe8f30SChristoph Hellwig case S_IFSOCK: 28761da177e4SLinus Torvalds flag &= ~O_TRUNC; 2877c8fe8f30SChristoph Hellwig break; 28784a3fd211SDave Hansen } 2879b41572e9SDave Hansen 288062fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2881b41572e9SDave Hansen if (error) 2882b41572e9SDave Hansen return error; 28836146f0d5SMimi Zohar 28841da177e4SLinus Torvalds /* 28851da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 28861da177e4SLinus Torvalds */ 28871da177e4SLinus Torvalds if (IS_APPEND(inode)) { 28888737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 28897715b521SAl Viro return -EPERM; 28901da177e4SLinus Torvalds if (flag & O_TRUNC) 28917715b521SAl Viro return -EPERM; 28921da177e4SLinus Torvalds } 28931da177e4SLinus Torvalds 28941da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 28952e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 28967715b521SAl Viro return -EPERM; 28971da177e4SLinus Torvalds 2898f3c7691eSJ. Bruce Fields return 0; 28997715b521SAl Viro } 29007715b521SAl Viro 2901e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 29027715b521SAl Viro { 2903f0bb5aafSAl Viro const struct path *path = &filp->f_path; 29047715b521SAl Viro struct inode *inode = path->dentry->d_inode; 29057715b521SAl Viro int error = get_write_access(inode); 29061da177e4SLinus Torvalds if (error) 29077715b521SAl Viro return error; 29081da177e4SLinus Torvalds /* 29091da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 29101da177e4SLinus Torvalds */ 2911d7a06983SJeff Layton error = locks_verify_locked(filp); 2912be6d3e56SKentaro Takeda if (!error) 2913ea0d3ab2STetsuo Handa error = security_path_truncate(path); 29141da177e4SLinus Torvalds if (!error) { 29157715b521SAl Viro error = do_truncate(path->dentry, 0, 2916d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2917e1181ee6SJeff Layton filp); 29181da177e4SLinus Torvalds } 29191da177e4SLinus Torvalds put_write_access(inode); 2920acd0c935SMimi Zohar return error; 29211da177e4SLinus Torvalds } 29221da177e4SLinus Torvalds 2923d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2924d57999e1SDave Hansen { 29258a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 29268a5e929dSAl Viro flag--; 2927d57999e1SDave Hansen return flag; 2928d57999e1SDave Hansen } 2929d57999e1SDave Hansen 2930d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 2931d18e9008SMiklos Szeredi { 2932d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2933d18e9008SMiklos Szeredi if (error) 2934d18e9008SMiklos Szeredi return error; 2935d18e9008SMiklos Szeredi 2936d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2937d18e9008SMiklos Szeredi if (error) 2938d18e9008SMiklos Szeredi return error; 2939d18e9008SMiklos Szeredi 2940d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2941d18e9008SMiklos Szeredi } 2942d18e9008SMiklos Szeredi 29431acf0af9SDavid Howells /* 29441acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 29451acf0af9SDavid Howells * dentry. 29461acf0af9SDavid Howells * 29471acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 29481acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 29491acf0af9SDavid Howells * 29501acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 29511acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 29521acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 29531acf0af9SDavid Howells * 29541acf0af9SDavid Howells * Returns an error code otherwise. 29551acf0af9SDavid Howells */ 29562675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 295730d90494SAl Viro struct path *path, struct file *file, 2958015c3bbcSMiklos Szeredi const struct open_flags *op, 29591643b43fSAl Viro int open_flag, umode_t mode, 296047237687SAl Viro int *opened) 2961d18e9008SMiklos Szeredi { 2962d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2963d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2964d18e9008SMiklos Szeredi int error; 2965d18e9008SMiklos Szeredi 2966384f26e2SAl Viro if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ 2967d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2968d18e9008SMiklos Szeredi 2969d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2970d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2971d18e9008SMiklos Szeredi 297230d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 297330d90494SAl Viro file->f_path.mnt = nd->path.mnt; 29740fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 29750fb1ea09SAl Viro open_to_namei_flags(open_flag), 29760fb1ea09SAl Viro mode, opened); 29776fbd0714SAl Viro d_lookup_done(dentry); 2978384f26e2SAl Viro if (!error) { 2979d18e9008SMiklos Szeredi /* 2980384f26e2SAl Viro * We didn't have the inode before the open, so check open 2981384f26e2SAl Viro * permission here. 2982d18e9008SMiklos Szeredi */ 2983384f26e2SAl Viro int acc_mode = op->acc_mode; 298403da633aSAl Viro if (*opened & FILE_CREATED) { 298503da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 298603da633aSAl Viro fsnotify_create(dir, dentry); 298762fb4a15SAl Viro acc_mode = 0; 298803da633aSAl Viro } 29892675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 2990384f26e2SAl Viro if (WARN_ON(error > 0)) 2991384f26e2SAl Viro error = -EINVAL; 2992384f26e2SAl Viro } else if (error > 0) { 2993d18e9008SMiklos Szeredi if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 2994d18e9008SMiklos Szeredi error = -EIO; 2995384f26e2SAl Viro } else { 2996d18e9008SMiklos Szeredi if (file->f_path.dentry) { 2997d18e9008SMiklos Szeredi dput(dentry); 2998d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 299910c64ceaSAl Viro } 3000d18e9008SMiklos Szeredi if (*opened & FILE_CREATED) 3001d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 3002a01e718fSAl Viro if (unlikely(d_is_negative(dentry))) { 3003a01e718fSAl Viro error = -ENOENT; 3004a01e718fSAl Viro } else { 3005d18e9008SMiklos Szeredi path->dentry = dentry; 3006d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 30072675a4ebSAl Viro return 1; 3008d18e9008SMiklos Szeredi } 3009d18e9008SMiklos Szeredi } 3010a01e718fSAl Viro } 3011d18e9008SMiklos Szeredi dput(dentry); 3012d18e9008SMiklos Szeredi return error; 3013d18e9008SMiklos Szeredi } 3014d18e9008SMiklos Szeredi 301531e6b01fSNick Piggin /* 30161acf0af9SDavid Howells * Look up and maybe create and open the last component. 3017d58ffd35SMiklos Szeredi * 3018d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 3019d58ffd35SMiklos Szeredi * 30201acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 30211acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 30221acf0af9SDavid Howells * 30231acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 30241acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 30251acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 30261acf0af9SDavid Howells * specified then a negative dentry may be returned. 30271acf0af9SDavid Howells * 30281acf0af9SDavid Howells * An error code is returned otherwise. 30291acf0af9SDavid Howells * 30301acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 30311acf0af9SDavid Howells * cleared otherwise prior to returning. 3032d58ffd35SMiklos Szeredi */ 30332675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 303430d90494SAl Viro struct file *file, 3035d58ffd35SMiklos Szeredi const struct open_flags *op, 303664894cf8SAl Viro bool got_write, int *opened) 3037d58ffd35SMiklos Szeredi { 3038d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 303954ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 30401643b43fSAl Viro int open_flag = op->open_flag; 3041d58ffd35SMiklos Szeredi struct dentry *dentry; 30421643b43fSAl Viro int error, create_error = 0; 30431643b43fSAl Viro umode_t mode = op->mode; 30446fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3045d58ffd35SMiklos Szeredi 3046ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3047ce8644fcSAl Viro return -ENOENT; 3048d58ffd35SMiklos Szeredi 304947237687SAl Viro *opened &= ~FILE_CREATED; 30506fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 30516fbd0714SAl Viro for (;;) { 30526fbd0714SAl Viro if (!dentry) { 30536fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3054d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 30552675a4ebSAl Viro return PTR_ERR(dentry); 30566fbd0714SAl Viro } 30576fbd0714SAl Viro if (d_in_lookup(dentry)) 30586fbd0714SAl Viro break; 3059d58ffd35SMiklos Szeredi 30606fbd0714SAl Viro if (!(dentry->d_flags & DCACHE_OP_REVALIDATE)) 30616fbd0714SAl Viro break; 30626fbd0714SAl Viro 30636fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 30646fbd0714SAl Viro if (likely(error > 0)) 30656fbd0714SAl Viro break; 30666fbd0714SAl Viro if (error) 30676fbd0714SAl Viro goto out_dput; 30686fbd0714SAl Viro d_invalidate(dentry); 30696fbd0714SAl Viro dput(dentry); 30706fbd0714SAl Viro dentry = NULL; 30716fbd0714SAl Viro } 30726fbd0714SAl Viro if (dentry->d_inode) { 3073d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3074d18e9008SMiklos Szeredi goto out_no_open; 30756c51e513SAl Viro } 3076d18e9008SMiklos Szeredi 30771643b43fSAl Viro /* 30781643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 30791643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 30801643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 30811643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 30821643b43fSAl Viro * 30831643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 30841643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 30851643b43fSAl Viro */ 30861643b43fSAl Viro if (open_flag & O_CREAT) { 30871643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 30881643b43fSAl Viro mode &= ~current_umask(); 30891643b43fSAl Viro if (unlikely(!got_write)) { 30901643b43fSAl Viro create_error = -EROFS; 30911643b43fSAl Viro open_flag &= ~O_CREAT; 30921643b43fSAl Viro if (open_flag & (O_EXCL | O_TRUNC)) 30931643b43fSAl Viro goto no_open; 30941643b43fSAl Viro /* No side effects, safe to clear O_CREAT */ 30951643b43fSAl Viro } else { 30961643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 30971643b43fSAl Viro if (create_error) { 30981643b43fSAl Viro open_flag &= ~O_CREAT; 30991643b43fSAl Viro if (open_flag & O_EXCL) 31001643b43fSAl Viro goto no_open; 31011643b43fSAl Viro } 31021643b43fSAl Viro } 31031643b43fSAl Viro } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && 31041643b43fSAl Viro unlikely(!got_write)) { 31051643b43fSAl Viro /* 31061643b43fSAl Viro * No O_CREATE -> atomicity not a requirement -> fall 31071643b43fSAl Viro * back to lookup + open 31081643b43fSAl Viro */ 31091643b43fSAl Viro goto no_open; 3110d18e9008SMiklos Szeredi } 3111d18e9008SMiklos Szeredi 31121643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 31131643b43fSAl Viro error = atomic_open(nd, dentry, path, file, op, open_flag, 31141643b43fSAl Viro mode, opened); 31151643b43fSAl Viro if (unlikely(error == -ENOENT) && create_error) 31161643b43fSAl Viro error = create_error; 31171643b43fSAl Viro return error; 31181643b43fSAl Viro } 311954ef4872SMiklos Szeredi 31201643b43fSAl Viro no_open: 31216fbd0714SAl Viro if (d_in_lookup(dentry)) { 312212fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 312312fa5e24SAl Viro nd->flags); 31246fbd0714SAl Viro d_lookup_done(dentry); 312512fa5e24SAl Viro if (unlikely(res)) { 312612fa5e24SAl Viro if (IS_ERR(res)) { 312712fa5e24SAl Viro error = PTR_ERR(res); 312812fa5e24SAl Viro goto out_dput; 312912fa5e24SAl Viro } 313012fa5e24SAl Viro dput(dentry); 313112fa5e24SAl Viro dentry = res; 313212fa5e24SAl Viro } 313354ef4872SMiklos Szeredi } 313454ef4872SMiklos Szeredi 3135d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 31361643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 313747237687SAl Viro *opened |= FILE_CREATED; 3138ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3139ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3140ce8644fcSAl Viro error = -EACCES; 3141d58ffd35SMiklos Szeredi goto out_dput; 314277d660a8SMiklos Szeredi } 3143ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 31441643b43fSAl Viro open_flag & O_EXCL); 3145d58ffd35SMiklos Szeredi if (error) 3146d58ffd35SMiklos Szeredi goto out_dput; 3147ce8644fcSAl Viro fsnotify_create(dir_inode, dentry); 3148d58ffd35SMiklos Szeredi } 31491643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 31501643b43fSAl Viro error = create_error; 3151d58ffd35SMiklos Szeredi goto out_dput; 3152d58ffd35SMiklos Szeredi } 3153d18e9008SMiklos Szeredi out_no_open: 3154d58ffd35SMiklos Szeredi path->dentry = dentry; 3155d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 31562675a4ebSAl Viro return 1; 3157d58ffd35SMiklos Szeredi 3158d58ffd35SMiklos Szeredi out_dput: 3159d58ffd35SMiklos Szeredi dput(dentry); 31602675a4ebSAl Viro return error; 3161d58ffd35SMiklos Szeredi } 3162d58ffd35SMiklos Szeredi 3163d58ffd35SMiklos Szeredi /* 3164fe2d35ffSAl Viro * Handle the last step of open() 316531e6b01fSNick Piggin */ 3166896475d5SAl Viro static int do_last(struct nameidata *nd, 316730d90494SAl Viro struct file *file, const struct open_flags *op, 316876ae2a5aSAl Viro int *opened) 3169fb1cc555SAl Viro { 3170a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3171ca344a89SAl Viro int open_flag = op->open_flag; 317277d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 317364894cf8SAl Viro bool got_write = false; 3174bcda7652SAl Viro int acc_mode = op->acc_mode; 3175254cf582SAl Viro unsigned seq; 3176a1eb3315SMiklos Szeredi struct inode *inode; 3177896475d5SAl Viro struct path path; 317816c2cd71SAl Viro int error; 3179fb1cc555SAl Viro 3180c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3181c3e380b0SAl Viro nd->flags |= op->intent; 3182c3e380b0SAl Viro 3183bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3184fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3185deb106c6SAl Viro if (unlikely(error)) 31862675a4ebSAl Viro return error; 3187e83db167SMiklos Szeredi goto finish_open; 31881f36f774SAl Viro } 3189a2c36b45SAl Viro 3190ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3191fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3192fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3193fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3194254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 3195e9742b53SAl Viro if (likely(error > 0)) 319671574865SMiklos Szeredi goto finish_lookup; 319771574865SMiklos Szeredi 3198ce57dfc1SAl Viro if (error < 0) 3199deb106c6SAl Viro return error; 3200a1eb3315SMiklos Szeredi 320137d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 32026583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3203b6183df7SMiklos Szeredi } else { 3204fe2d35ffSAl Viro /* create side of things */ 3205a3fbbde7SAl Viro /* 3206b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3207b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3208b6183df7SMiklos Szeredi * about to look up 3209a3fbbde7SAl Viro */ 32109f1fafeeSAl Viro error = complete_walk(nd); 3211e8bb73dfSAl Viro if (error) 32122675a4ebSAl Viro return error; 3213fe2d35ffSAl Viro 321476ae2a5aSAl Viro audit_inode(nd->name, dir, LOOKUP_PARENT); 32151f36f774SAl Viro /* trailing slashes? */ 3216deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3217deb106c6SAl Viro return -EISDIR; 3218b6183df7SMiklos Szeredi } 32191f36f774SAl Viro 32209cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 322164894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 322264894cf8SAl Viro if (!error) 322364894cf8SAl Viro got_write = true; 322464894cf8SAl Viro /* 322564894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 322664894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 322764894cf8SAl Viro * dropping this one anyway. 322864894cf8SAl Viro */ 322964894cf8SAl Viro } 32309cf843e3SAl Viro if (open_flag & O_CREAT) 32315955102cSAl Viro inode_lock(dir->d_inode); 32329cf843e3SAl Viro else 32339cf843e3SAl Viro inode_lock_shared(dir->d_inode); 3234896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 32359cf843e3SAl Viro if (open_flag & O_CREAT) 32365955102cSAl Viro inode_unlock(dir->d_inode); 32379cf843e3SAl Viro else 32389cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3239fb1cc555SAl Viro 32402675a4ebSAl Viro if (error <= 0) { 32412675a4ebSAl Viro if (error) 3242d58ffd35SMiklos Szeredi goto out; 32436c0d46c4SAl Viro 324447237687SAl Viro if ((*opened & FILE_CREATED) || 3245496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 324677d660a8SMiklos Szeredi will_truncate = false; 3247d18e9008SMiklos Szeredi 324876ae2a5aSAl Viro audit_inode(nd->name, file->f_path.dentry, 0); 3249d18e9008SMiklos Szeredi goto opened; 3250d18e9008SMiklos Szeredi } 3251d18e9008SMiklos Szeredi 325247237687SAl Viro if (*opened & FILE_CREATED) { 32539b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3254ca344a89SAl Viro open_flag &= ~O_TRUNC; 325577d660a8SMiklos Szeredi will_truncate = false; 325662fb4a15SAl Viro acc_mode = 0; 3257896475d5SAl Viro path_to_nameidata(&path, nd); 3258e83db167SMiklos Szeredi goto finish_open_created; 3259fb1cc555SAl Viro } 3260fb1cc555SAl Viro 3261fb1cc555SAl Viro /* 3262d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3263d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3264d18e9008SMiklos Szeredi * necessary...) 3265d18e9008SMiklos Szeredi */ 326664894cf8SAl Viro if (got_write) { 3267d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 326864894cf8SAl Viro got_write = false; 3269d18e9008SMiklos Szeredi } 3270d18e9008SMiklos Szeredi 3271e6ec03a2SAl Viro error = follow_managed(&path, nd); 3272e6ec03a2SAl Viro if (unlikely(error < 0)) 3273e6ec03a2SAl Viro return error; 3274e6ec03a2SAl Viro 32756583fe22SAl Viro if (unlikely(d_is_negative(path.dentry))) { 32766583fe22SAl Viro path_to_nameidata(&path, nd); 32776583fe22SAl Viro return -ENOENT; 32786583fe22SAl Viro } 32796583fe22SAl Viro 32806583fe22SAl Viro /* 32816583fe22SAl Viro * create/update audit record if it already exists. 32826583fe22SAl Viro */ 32836583fe22SAl Viro audit_inode(nd->name, path.dentry, 0); 32846583fe22SAl Viro 3285deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3286deb106c6SAl Viro path_to_nameidata(&path, nd); 3287deb106c6SAl Viro return -EEXIST; 3288deb106c6SAl Viro } 3289fb1cc555SAl Viro 3290254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3291d4565649SAl Viro inode = d_backing_inode(path.dentry); 3292766c4cbfSAl Viro finish_lookup: 32938f64fb1cSAl Viro error = step_into(nd, &path, 0, inode, seq); 3294deb106c6SAl Viro if (unlikely(error)) 3295d63ff28fSAl Viro return error; 3296bc77daa7SAl Viro finish_open: 32978f64fb1cSAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3298a3fbbde7SAl Viro error = complete_walk(nd); 3299fac7d191SAl Viro if (error) 33002675a4ebSAl Viro return error; 330176ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 3302fb1cc555SAl Viro error = -EISDIR; 330344b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 33042675a4ebSAl Viro goto out; 3305af2f5542SMiklos Szeredi error = -ENOTDIR; 330644b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 33072675a4ebSAl Viro goto out; 33084bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 330977d660a8SMiklos Szeredi will_truncate = false; 33106c0d46c4SAl Viro 33110f9d1a10SAl Viro if (will_truncate) { 33120f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 33130f9d1a10SAl Viro if (error) 33142675a4ebSAl Viro goto out; 331564894cf8SAl Viro got_write = true; 33160f9d1a10SAl Viro } 3317e83db167SMiklos Szeredi finish_open_created: 3318bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3319ca344a89SAl Viro if (error) 33202675a4ebSAl Viro goto out; 33214aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 33224aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 3323fac7d191SAl Viro if (error) 3324015c3bbcSMiklos Szeredi goto out; 3325fac7d191SAl Viro *opened |= FILE_OPENED; 3326a8277b9bSMiklos Szeredi opened: 33272675a4ebSAl Viro error = open_check_o_direct(file); 3328fe9ec829SAl Viro if (!error) 33293034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3330fe9ec829SAl Viro if (!error && will_truncate) 33312675a4ebSAl Viro error = handle_truncate(file); 3332ca344a89SAl Viro out: 3333fe9ec829SAl Viro if (unlikely(error) && (*opened & FILE_OPENED)) 3334fe9ec829SAl Viro fput(file); 3335c80567c8SAl Viro if (unlikely(error > 0)) { 3336c80567c8SAl Viro WARN_ON(1); 3337c80567c8SAl Viro error = -EINVAL; 3338c80567c8SAl Viro } 333964894cf8SAl Viro if (got_write) 33400f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 33412675a4ebSAl Viro return error; 3342fb1cc555SAl Viro } 3343fb1cc555SAl Viro 3344c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 334560545d0dSAl Viro const struct open_flags *op, 334660545d0dSAl Viro struct file *file, int *opened) 334760545d0dSAl Viro { 334860545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 3349625b6d10SAl Viro struct dentry *child; 335060545d0dSAl Viro struct inode *dir; 3351625b6d10SAl Viro struct path path; 3352c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 335360545d0dSAl Viro if (unlikely(error)) 335460545d0dSAl Viro return error; 3355625b6d10SAl Viro error = mnt_want_write(path.mnt); 335660545d0dSAl Viro if (unlikely(error)) 335760545d0dSAl Viro goto out; 3358625b6d10SAl Viro dir = path.dentry->d_inode; 335960545d0dSAl Viro /* we want directory to be writable */ 3360625b6d10SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 336160545d0dSAl Viro if (error) 336260545d0dSAl Viro goto out2; 336360545d0dSAl Viro if (!dir->i_op->tmpfile) { 336460545d0dSAl Viro error = -EOPNOTSUPP; 336560545d0dSAl Viro goto out2; 336660545d0dSAl Viro } 3367625b6d10SAl Viro child = d_alloc(path.dentry, &name); 336860545d0dSAl Viro if (unlikely(!child)) { 336960545d0dSAl Viro error = -ENOMEM; 337060545d0dSAl Viro goto out2; 337160545d0dSAl Viro } 3372625b6d10SAl Viro dput(path.dentry); 3373625b6d10SAl Viro path.dentry = child; 3374625b6d10SAl Viro error = dir->i_op->tmpfile(dir, child, op->mode); 337560545d0dSAl Viro if (error) 337660545d0dSAl Viro goto out2; 3377c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 337869a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 337962fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 338060545d0dSAl Viro if (error) 338160545d0dSAl Viro goto out2; 3382625b6d10SAl Viro file->f_path.mnt = path.mnt; 3383625b6d10SAl Viro error = finish_open(file, child, NULL, opened); 338460545d0dSAl Viro if (error) 338560545d0dSAl Viro goto out2; 338660545d0dSAl Viro error = open_check_o_direct(file); 3387f4e0c30cSAl Viro if (error) { 338860545d0dSAl Viro fput(file); 3389f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3390f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3391f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3392f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3393f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3394f4e0c30cSAl Viro } 339560545d0dSAl Viro out2: 3396625b6d10SAl Viro mnt_drop_write(path.mnt); 339760545d0dSAl Viro out: 3398625b6d10SAl Viro path_put(&path); 339960545d0dSAl Viro return error; 340060545d0dSAl Viro } 340160545d0dSAl Viro 34026ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 34036ac08709SAl Viro { 34046ac08709SAl Viro struct path path; 34056ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 34066ac08709SAl Viro if (!error) { 34076ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 34086ac08709SAl Viro error = vfs_open(&path, file, current_cred()); 34096ac08709SAl Viro path_put(&path); 34106ac08709SAl Viro } 34116ac08709SAl Viro return error; 34126ac08709SAl Viro } 34136ac08709SAl Viro 3414c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3415c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 34161da177e4SLinus Torvalds { 3417368ee9baSAl Viro const char *s; 341830d90494SAl Viro struct file *file; 341947237687SAl Viro int opened = 0; 342013aab428SAl Viro int error; 342131e6b01fSNick Piggin 342230d90494SAl Viro file = get_empty_filp(); 34231afc99beSAl Viro if (IS_ERR(file)) 34241afc99beSAl Viro return file; 342531e6b01fSNick Piggin 342630d90494SAl Viro file->f_flags = op->open_flag; 342731e6b01fSNick Piggin 3428bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 3429c8a53ee5SAl Viro error = do_tmpfile(nd, flags, op, file, &opened); 3430f15133dfSAl Viro goto out2; 343160545d0dSAl Viro } 343260545d0dSAl Viro 34336ac08709SAl Viro if (unlikely(file->f_flags & O_PATH)) { 34346ac08709SAl Viro error = do_o_path(nd, flags, file); 34356ac08709SAl Viro if (!error) 34366ac08709SAl Viro opened |= FILE_OPENED; 34376ac08709SAl Viro goto out2; 34386ac08709SAl Viro } 34396ac08709SAl Viro 3440c8a53ee5SAl Viro s = path_init(nd, flags); 3441368ee9baSAl Viro if (IS_ERR(s)) { 3442368ee9baSAl Viro put_filp(file); 3443368ee9baSAl Viro return ERR_CAST(s); 3444368ee9baSAl Viro } 34453bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 344676ae2a5aSAl Viro (error = do_last(nd, file, op, &opened)) > 0) { 344773d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 34483bdba28bSAl Viro s = trailing_symlink(nd); 34493bdba28bSAl Viro if (IS_ERR(s)) { 34503bdba28bSAl Viro error = PTR_ERR(s); 34512675a4ebSAl Viro break; 3452806b681cSAl Viro } 34533bdba28bSAl Viro } 3454deb106c6SAl Viro terminate_walk(nd); 3455f15133dfSAl Viro out2: 34562675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 34572675a4ebSAl Viro BUG_ON(!error); 345830d90494SAl Viro put_filp(file); 3459015c3bbcSMiklos Szeredi } 34602675a4ebSAl Viro if (unlikely(error)) { 34612675a4ebSAl Viro if (error == -EOPENSTALE) { 34622675a4ebSAl Viro if (flags & LOOKUP_RCU) 34632675a4ebSAl Viro error = -ECHILD; 34642675a4ebSAl Viro else 34652675a4ebSAl Viro error = -ESTALE; 34662675a4ebSAl Viro } 34672675a4ebSAl Viro file = ERR_PTR(error); 34682675a4ebSAl Viro } 34692675a4ebSAl Viro return file; 3470de459215SKirill Korotaev } 34711da177e4SLinus Torvalds 3472669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3473f9652e10SAl Viro const struct open_flags *op) 347413aab428SAl Viro { 34759883d185SAl Viro struct nameidata nd; 3476f9652e10SAl Viro int flags = op->lookup_flags; 347713aab428SAl Viro struct file *filp; 347813aab428SAl Viro 34799883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3480c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 348113aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3482c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 348313aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3484c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 34859883d185SAl Viro restore_nameidata(); 348613aab428SAl Viro return filp; 348713aab428SAl Viro } 348813aab428SAl Viro 348973d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3490f9652e10SAl Viro const char *name, const struct open_flags *op) 349173d049a4SAl Viro { 34929883d185SAl Viro struct nameidata nd; 349373d049a4SAl Viro struct file *file; 349451689104SPaul Moore struct filename *filename; 3495f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 349673d049a4SAl Viro 349773d049a4SAl Viro nd.root.mnt = mnt; 349873d049a4SAl Viro nd.root.dentry = dentry; 349973d049a4SAl Viro 3500b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 350173d049a4SAl Viro return ERR_PTR(-ELOOP); 350273d049a4SAl Viro 350351689104SPaul Moore filename = getname_kernel(name); 3504a1c83681SViresh Kumar if (IS_ERR(filename)) 350551689104SPaul Moore return ERR_CAST(filename); 350651689104SPaul Moore 35079883d185SAl Viro set_nameidata(&nd, -1, filename); 3508c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 350973d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3510c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 351173d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3512c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 35139883d185SAl Viro restore_nameidata(); 351451689104SPaul Moore putname(filename); 351573d049a4SAl Viro return file; 351673d049a4SAl Viro } 351773d049a4SAl Viro 3518fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 35191ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 35201da177e4SLinus Torvalds { 3521c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3522391172c4SAl Viro struct qstr last; 3523391172c4SAl Viro int type; 3524c30dabfeSJan Kara int err2; 35251ac12b4bSJeff Layton int error; 35261ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 35271ac12b4bSJeff Layton 35281ac12b4bSJeff Layton /* 35291ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 35301ac12b4bSJeff Layton * other flags passed in are ignored! 35311ac12b4bSJeff Layton */ 35321ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 35331ac12b4bSJeff Layton 35345c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 35355c31b6ceSAl Viro if (IS_ERR(name)) 35365c31b6ceSAl Viro return ERR_CAST(name); 35371da177e4SLinus Torvalds 3538c663e5d8SChristoph Hellwig /* 3539c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3540c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3541c663e5d8SChristoph Hellwig */ 35425c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3543ed75e95dSAl Viro goto out; 3544c663e5d8SChristoph Hellwig 3545c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3546391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3547c663e5d8SChristoph Hellwig /* 3548c663e5d8SChristoph Hellwig * Do the final lookup. 3549c663e5d8SChristoph Hellwig */ 3550391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 35515955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3552391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 35531da177e4SLinus Torvalds if (IS_ERR(dentry)) 3554a8104a9fSAl Viro goto unlock; 3555c663e5d8SChristoph Hellwig 3556a8104a9fSAl Viro error = -EEXIST; 3557b18825a7SDavid Howells if (d_is_positive(dentry)) 3558a8104a9fSAl Viro goto fail; 3559b18825a7SDavid Howells 3560c663e5d8SChristoph Hellwig /* 3561c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3562c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3563c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3564c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3565c663e5d8SChristoph Hellwig */ 3566391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3567a8104a9fSAl Viro error = -ENOENT; 3568ed75e95dSAl Viro goto fail; 3569e9baf6e5SAl Viro } 3570c30dabfeSJan Kara if (unlikely(err2)) { 3571c30dabfeSJan Kara error = err2; 3572a8104a9fSAl Viro goto fail; 3573c30dabfeSJan Kara } 3574181c37b6SAl Viro putname(name); 3575e9baf6e5SAl Viro return dentry; 35761da177e4SLinus Torvalds fail: 3577a8104a9fSAl Viro dput(dentry); 3578a8104a9fSAl Viro dentry = ERR_PTR(error); 3579a8104a9fSAl Viro unlock: 35805955102cSAl Viro inode_unlock(path->dentry->d_inode); 3581c30dabfeSJan Kara if (!err2) 3582391172c4SAl Viro mnt_drop_write(path->mnt); 3583ed75e95dSAl Viro out: 3584391172c4SAl Viro path_put(path); 3585181c37b6SAl Viro putname(name); 3586ed75e95dSAl Viro return dentry; 3587dae6ad8fSAl Viro } 3588fa14a0b8SAl Viro 3589fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3590fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3591fa14a0b8SAl Viro { 3592181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3593181c37b6SAl Viro path, lookup_flags); 3594fa14a0b8SAl Viro } 3595dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3596dae6ad8fSAl Viro 3597921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3598921a1650SAl Viro { 3599921a1650SAl Viro dput(dentry); 36005955102cSAl Viro inode_unlock(path->dentry->d_inode); 3601a8104a9fSAl Viro mnt_drop_write(path->mnt); 3602921a1650SAl Viro path_put(path); 3603921a1650SAl Viro } 3604921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3605921a1650SAl Viro 3606520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 36071ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3608dae6ad8fSAl Viro { 3609181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3610dae6ad8fSAl Viro } 3611dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3612dae6ad8fSAl Viro 36131a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 36141da177e4SLinus Torvalds { 3615a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36161da177e4SLinus Torvalds 36171da177e4SLinus Torvalds if (error) 36181da177e4SLinus Torvalds return error; 36191da177e4SLinus Torvalds 3620975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 36211da177e4SLinus Torvalds return -EPERM; 36221da177e4SLinus Torvalds 3623acfa4380SAl Viro if (!dir->i_op->mknod) 36241da177e4SLinus Torvalds return -EPERM; 36251da177e4SLinus Torvalds 362608ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 362708ce5f16SSerge E. Hallyn if (error) 362808ce5f16SSerge E. Hallyn return error; 362908ce5f16SSerge E. Hallyn 36301da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 36311da177e4SLinus Torvalds if (error) 36321da177e4SLinus Torvalds return error; 36331da177e4SLinus Torvalds 36341da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3635a74574aaSStephen Smalley if (!error) 3636f38aa942SAmy Griffis fsnotify_create(dir, dentry); 36371da177e4SLinus Torvalds return error; 36381da177e4SLinus Torvalds } 36394d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 36401da177e4SLinus Torvalds 3641f69aac00SAl Viro static int may_mknod(umode_t mode) 3642463c3197SDave Hansen { 3643463c3197SDave Hansen switch (mode & S_IFMT) { 3644463c3197SDave Hansen case S_IFREG: 3645463c3197SDave Hansen case S_IFCHR: 3646463c3197SDave Hansen case S_IFBLK: 3647463c3197SDave Hansen case S_IFIFO: 3648463c3197SDave Hansen case S_IFSOCK: 3649463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3650463c3197SDave Hansen return 0; 3651463c3197SDave Hansen case S_IFDIR: 3652463c3197SDave Hansen return -EPERM; 3653463c3197SDave Hansen default: 3654463c3197SDave Hansen return -EINVAL; 3655463c3197SDave Hansen } 3656463c3197SDave Hansen } 3657463c3197SDave Hansen 36588208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 36592e4d0924SHeiko Carstens unsigned, dev) 36601da177e4SLinus Torvalds { 36611da177e4SLinus Torvalds struct dentry *dentry; 3662dae6ad8fSAl Viro struct path path; 3663dae6ad8fSAl Viro int error; 3664972567f1SJeff Layton unsigned int lookup_flags = 0; 36651da177e4SLinus Torvalds 36668e4bfca1SAl Viro error = may_mknod(mode); 36678e4bfca1SAl Viro if (error) 36688e4bfca1SAl Viro return error; 3669972567f1SJeff Layton retry: 3670972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3671dae6ad8fSAl Viro if (IS_ERR(dentry)) 3672dae6ad8fSAl Viro return PTR_ERR(dentry); 36732ad94ae6SAl Viro 3674dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3675ce3b0f8dSAl Viro mode &= ~current_umask(); 3676dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3677be6d3e56SKentaro Takeda if (error) 3678a8104a9fSAl Viro goto out; 36791da177e4SLinus Torvalds switch (mode & S_IFMT) { 36801da177e4SLinus Torvalds case 0: case S_IFREG: 3681312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 368205d1a717SMimi Zohar if (!error) 368305d1a717SMimi Zohar ima_post_path_mknod(dentry); 36841da177e4SLinus Torvalds break; 36851da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3686dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 36871da177e4SLinus Torvalds new_decode_dev(dev)); 36881da177e4SLinus Torvalds break; 36891da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3690dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 36911da177e4SLinus Torvalds break; 36921da177e4SLinus Torvalds } 3693a8104a9fSAl Viro out: 3694921a1650SAl Viro done_path_create(&path, dentry); 3695972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3696972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3697972567f1SJeff Layton goto retry; 3698972567f1SJeff Layton } 36991da177e4SLinus Torvalds return error; 37001da177e4SLinus Torvalds } 37011da177e4SLinus Torvalds 37028208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 37035590ff0dSUlrich Drepper { 37045590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 37055590ff0dSUlrich Drepper } 37065590ff0dSUlrich Drepper 370718bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 37081da177e4SLinus Torvalds { 3709a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 37108de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 37111da177e4SLinus Torvalds 37121da177e4SLinus Torvalds if (error) 37131da177e4SLinus Torvalds return error; 37141da177e4SLinus Torvalds 3715acfa4380SAl Viro if (!dir->i_op->mkdir) 37161da177e4SLinus Torvalds return -EPERM; 37171da177e4SLinus Torvalds 37181da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 37191da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 37201da177e4SLinus Torvalds if (error) 37211da177e4SLinus Torvalds return error; 37221da177e4SLinus Torvalds 37238de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 37248de52778SAl Viro return -EMLINK; 37258de52778SAl Viro 37261da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3727a74574aaSStephen Smalley if (!error) 3728f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 37291da177e4SLinus Torvalds return error; 37301da177e4SLinus Torvalds } 37314d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 37321da177e4SLinus Torvalds 3733a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 37341da177e4SLinus Torvalds { 37356902d925SDave Hansen struct dentry *dentry; 3736dae6ad8fSAl Viro struct path path; 3737dae6ad8fSAl Viro int error; 3738b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 37391da177e4SLinus Torvalds 3740b76d8b82SJeff Layton retry: 3741b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 37426902d925SDave Hansen if (IS_ERR(dentry)) 3743dae6ad8fSAl Viro return PTR_ERR(dentry); 37446902d925SDave Hansen 3745dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3746ce3b0f8dSAl Viro mode &= ~current_umask(); 3747dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3748a8104a9fSAl Viro if (!error) 3749dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3750921a1650SAl Viro done_path_create(&path, dentry); 3751b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3752b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3753b76d8b82SJeff Layton goto retry; 3754b76d8b82SJeff Layton } 37551da177e4SLinus Torvalds return error; 37561da177e4SLinus Torvalds } 37571da177e4SLinus Torvalds 3758a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 37595590ff0dSUlrich Drepper { 37605590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 37615590ff0dSUlrich Drepper } 37625590ff0dSUlrich Drepper 37631da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 37641da177e4SLinus Torvalds { 37651da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 37661da177e4SLinus Torvalds 37671da177e4SLinus Torvalds if (error) 37681da177e4SLinus Torvalds return error; 37691da177e4SLinus Torvalds 3770acfa4380SAl Viro if (!dir->i_op->rmdir) 37711da177e4SLinus Torvalds return -EPERM; 37721da177e4SLinus Torvalds 37731d2ef590SAl Viro dget(dentry); 37745955102cSAl Viro inode_lock(dentry->d_inode); 3775912dbc15SSage Weil 37761da177e4SLinus Torvalds error = -EBUSY; 37777af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3778912dbc15SSage Weil goto out; 3779912dbc15SSage Weil 37801da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3781912dbc15SSage Weil if (error) 3782912dbc15SSage Weil goto out; 3783912dbc15SSage Weil 37843cebde24SSage Weil shrink_dcache_parent(dentry); 37851da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3786912dbc15SSage Weil if (error) 3787912dbc15SSage Weil goto out; 3788912dbc15SSage Weil 37891da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3790d83c49f3SAl Viro dont_mount(dentry); 37918ed936b5SEric W. Biederman detach_mounts(dentry); 37921da177e4SLinus Torvalds 3793912dbc15SSage Weil out: 37945955102cSAl Viro inode_unlock(dentry->d_inode); 37951d2ef590SAl Viro dput(dentry); 3796912dbc15SSage Weil if (!error) 3797912dbc15SSage Weil d_delete(dentry); 37981da177e4SLinus Torvalds return error; 37991da177e4SLinus Torvalds } 38004d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 38011da177e4SLinus Torvalds 38025590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 38031da177e4SLinus Torvalds { 38041da177e4SLinus Torvalds int error = 0; 380591a27b2aSJeff Layton struct filename *name; 38061da177e4SLinus Torvalds struct dentry *dentry; 3807f5beed75SAl Viro struct path path; 3808f5beed75SAl Viro struct qstr last; 3809f5beed75SAl Viro int type; 3810c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3811c6ee9206SJeff Layton retry: 3812c1d4dd27SAl Viro name = filename_parentat(dfd, getname(pathname), lookup_flags, 3813c1d4dd27SAl Viro &path, &last, &type); 381491a27b2aSJeff Layton if (IS_ERR(name)) 381591a27b2aSJeff Layton return PTR_ERR(name); 38161da177e4SLinus Torvalds 3817f5beed75SAl Viro switch (type) { 38181da177e4SLinus Torvalds case LAST_DOTDOT: 38191da177e4SLinus Torvalds error = -ENOTEMPTY; 38201da177e4SLinus Torvalds goto exit1; 38211da177e4SLinus Torvalds case LAST_DOT: 38221da177e4SLinus Torvalds error = -EINVAL; 38231da177e4SLinus Torvalds goto exit1; 38241da177e4SLinus Torvalds case LAST_ROOT: 38251da177e4SLinus Torvalds error = -EBUSY; 38261da177e4SLinus Torvalds goto exit1; 38271da177e4SLinus Torvalds } 38280612d9fbSOGAWA Hirofumi 3829f5beed75SAl Viro error = mnt_want_write(path.mnt); 3830c30dabfeSJan Kara if (error) 3831c30dabfeSJan Kara goto exit1; 38320612d9fbSOGAWA Hirofumi 38335955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3834f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38351da177e4SLinus Torvalds error = PTR_ERR(dentry); 38366902d925SDave Hansen if (IS_ERR(dentry)) 38376902d925SDave Hansen goto exit2; 3838e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3839e6bc45d6STheodore Ts'o error = -ENOENT; 3840e6bc45d6STheodore Ts'o goto exit3; 3841e6bc45d6STheodore Ts'o } 3842f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3843be6d3e56SKentaro Takeda if (error) 3844c30dabfeSJan Kara goto exit3; 3845f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 38460622753bSDave Hansen exit3: 38471da177e4SLinus Torvalds dput(dentry); 38486902d925SDave Hansen exit2: 38495955102cSAl Viro inode_unlock(path.dentry->d_inode); 3850f5beed75SAl Viro mnt_drop_write(path.mnt); 38511da177e4SLinus Torvalds exit1: 3852f5beed75SAl Viro path_put(&path); 38531da177e4SLinus Torvalds putname(name); 3854c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3855c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3856c6ee9206SJeff Layton goto retry; 3857c6ee9206SJeff Layton } 38581da177e4SLinus Torvalds return error; 38591da177e4SLinus Torvalds } 38601da177e4SLinus Torvalds 38613cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 38625590ff0dSUlrich Drepper { 38635590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 38645590ff0dSUlrich Drepper } 38655590ff0dSUlrich Drepper 3866b21996e3SJ. Bruce Fields /** 3867b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3868b21996e3SJ. Bruce Fields * @dir: parent directory 3869b21996e3SJ. Bruce Fields * @dentry: victim 3870b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3871b21996e3SJ. Bruce Fields * 3872b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3873b21996e3SJ. Bruce Fields * 3874b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3875b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3876b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3877b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3878b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3879b21996e3SJ. Bruce Fields * 3880b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3881b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3882b21996e3SJ. Bruce Fields * to be NFS exported. 3883b21996e3SJ. Bruce Fields */ 3884b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 38851da177e4SLinus Torvalds { 38869accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 38871da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 38881da177e4SLinus Torvalds 38891da177e4SLinus Torvalds if (error) 38901da177e4SLinus Torvalds return error; 38911da177e4SLinus Torvalds 3892acfa4380SAl Viro if (!dir->i_op->unlink) 38931da177e4SLinus Torvalds return -EPERM; 38941da177e4SLinus Torvalds 38955955102cSAl Viro inode_lock(target); 38968ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 38971da177e4SLinus Torvalds error = -EBUSY; 38981da177e4SLinus Torvalds else { 38991da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3900bec1052eSAl Viro if (!error) { 39015a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 39025a14696cSJ. Bruce Fields if (error) 3903b21996e3SJ. Bruce Fields goto out; 39041da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 39058ed936b5SEric W. Biederman if (!error) { 3906d83c49f3SAl Viro dont_mount(dentry); 39078ed936b5SEric W. Biederman detach_mounts(dentry); 39088ed936b5SEric W. Biederman } 3909bec1052eSAl Viro } 39101da177e4SLinus Torvalds } 3911b21996e3SJ. Bruce Fields out: 39125955102cSAl Viro inode_unlock(target); 39131da177e4SLinus Torvalds 39141da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 39151da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 39169accbb97SJ. Bruce Fields fsnotify_link_count(target); 39171da177e4SLinus Torvalds d_delete(dentry); 39181da177e4SLinus Torvalds } 39190eeca283SRobert Love 39201da177e4SLinus Torvalds return error; 39211da177e4SLinus Torvalds } 39224d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 39231da177e4SLinus Torvalds 39241da177e4SLinus Torvalds /* 39251da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 39261b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 39271da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 39281da177e4SLinus Torvalds * while waiting on the I/O. 39291da177e4SLinus Torvalds */ 39305590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 39311da177e4SLinus Torvalds { 39322ad94ae6SAl Viro int error; 393391a27b2aSJeff Layton struct filename *name; 39341da177e4SLinus Torvalds struct dentry *dentry; 3935f5beed75SAl Viro struct path path; 3936f5beed75SAl Viro struct qstr last; 3937f5beed75SAl Viro int type; 39381da177e4SLinus Torvalds struct inode *inode = NULL; 3939b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 39405d18f813SJeff Layton unsigned int lookup_flags = 0; 39415d18f813SJeff Layton retry: 3942c1d4dd27SAl Viro name = filename_parentat(dfd, getname(pathname), lookup_flags, 3943c1d4dd27SAl Viro &path, &last, &type); 394491a27b2aSJeff Layton if (IS_ERR(name)) 394591a27b2aSJeff Layton return PTR_ERR(name); 39462ad94ae6SAl Viro 39471da177e4SLinus Torvalds error = -EISDIR; 3948f5beed75SAl Viro if (type != LAST_NORM) 39491da177e4SLinus Torvalds goto exit1; 39500612d9fbSOGAWA Hirofumi 3951f5beed75SAl Viro error = mnt_want_write(path.mnt); 3952c30dabfeSJan Kara if (error) 3953c30dabfeSJan Kara goto exit1; 3954b21996e3SJ. Bruce Fields retry_deleg: 39555955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3956f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 39571da177e4SLinus Torvalds error = PTR_ERR(dentry); 39581da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 39591da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3960f5beed75SAl Viro if (last.name[last.len]) 396150338b88STörök Edwin goto slashes; 39621da177e4SLinus Torvalds inode = dentry->d_inode; 3963b18825a7SDavid Howells if (d_is_negative(dentry)) 3964e6bc45d6STheodore Ts'o goto slashes; 39657de9c6eeSAl Viro ihold(inode); 3966f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3967be6d3e56SKentaro Takeda if (error) 3968c30dabfeSJan Kara goto exit2; 3969f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 39701da177e4SLinus Torvalds exit2: 39711da177e4SLinus Torvalds dput(dentry); 39721da177e4SLinus Torvalds } 39735955102cSAl Viro inode_unlock(path.dentry->d_inode); 39741da177e4SLinus Torvalds if (inode) 39751da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3976b21996e3SJ. Bruce Fields inode = NULL; 3977b21996e3SJ. Bruce Fields if (delegated_inode) { 39785a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3979b21996e3SJ. Bruce Fields if (!error) 3980b21996e3SJ. Bruce Fields goto retry_deleg; 3981b21996e3SJ. Bruce Fields } 3982f5beed75SAl Viro mnt_drop_write(path.mnt); 39831da177e4SLinus Torvalds exit1: 3984f5beed75SAl Viro path_put(&path); 39851da177e4SLinus Torvalds putname(name); 39865d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 39875d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 39885d18f813SJeff Layton inode = NULL; 39895d18f813SJeff Layton goto retry; 39905d18f813SJeff Layton } 39911da177e4SLinus Torvalds return error; 39921da177e4SLinus Torvalds 39931da177e4SLinus Torvalds slashes: 3994b18825a7SDavid Howells if (d_is_negative(dentry)) 3995b18825a7SDavid Howells error = -ENOENT; 399644b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3997b18825a7SDavid Howells error = -EISDIR; 3998b18825a7SDavid Howells else 3999b18825a7SDavid Howells error = -ENOTDIR; 40001da177e4SLinus Torvalds goto exit2; 40011da177e4SLinus Torvalds } 40021da177e4SLinus Torvalds 40032e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 40045590ff0dSUlrich Drepper { 40055590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 40065590ff0dSUlrich Drepper return -EINVAL; 40075590ff0dSUlrich Drepper 40085590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 40095590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 40105590ff0dSUlrich Drepper 40115590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 40125590ff0dSUlrich Drepper } 40135590ff0dSUlrich Drepper 40143480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 40155590ff0dSUlrich Drepper { 40165590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 40175590ff0dSUlrich Drepper } 40185590ff0dSUlrich Drepper 4019db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 40201da177e4SLinus Torvalds { 4021a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 40221da177e4SLinus Torvalds 40231da177e4SLinus Torvalds if (error) 40241da177e4SLinus Torvalds return error; 40251da177e4SLinus Torvalds 4026acfa4380SAl Viro if (!dir->i_op->symlink) 40271da177e4SLinus Torvalds return -EPERM; 40281da177e4SLinus Torvalds 40291da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 40301da177e4SLinus Torvalds if (error) 40311da177e4SLinus Torvalds return error; 40321da177e4SLinus Torvalds 40331da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 4034a74574aaSStephen Smalley if (!error) 4035f38aa942SAmy Griffis fsnotify_create(dir, dentry); 40361da177e4SLinus Torvalds return error; 40371da177e4SLinus Torvalds } 40384d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 40391da177e4SLinus Torvalds 40402e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 40412e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 40421da177e4SLinus Torvalds { 40432ad94ae6SAl Viro int error; 404491a27b2aSJeff Layton struct filename *from; 40456902d925SDave Hansen struct dentry *dentry; 4046dae6ad8fSAl Viro struct path path; 4047f46d3567SJeff Layton unsigned int lookup_flags = 0; 40481da177e4SLinus Torvalds 40491da177e4SLinus Torvalds from = getname(oldname); 40501da177e4SLinus Torvalds if (IS_ERR(from)) 40511da177e4SLinus Torvalds return PTR_ERR(from); 4052f46d3567SJeff Layton retry: 4053f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 40541da177e4SLinus Torvalds error = PTR_ERR(dentry); 40556902d925SDave Hansen if (IS_ERR(dentry)) 4056dae6ad8fSAl Viro goto out_putname; 40576902d925SDave Hansen 405891a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4059a8104a9fSAl Viro if (!error) 406091a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4061921a1650SAl Viro done_path_create(&path, dentry); 4062f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4063f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4064f46d3567SJeff Layton goto retry; 4065f46d3567SJeff Layton } 40666902d925SDave Hansen out_putname: 40671da177e4SLinus Torvalds putname(from); 40681da177e4SLinus Torvalds return error; 40691da177e4SLinus Torvalds } 40701da177e4SLinus Torvalds 40713480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 40725590ff0dSUlrich Drepper { 40735590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 40745590ff0dSUlrich Drepper } 40755590ff0dSUlrich Drepper 4076146a8595SJ. Bruce Fields /** 4077146a8595SJ. Bruce Fields * vfs_link - create a new link 4078146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4079146a8595SJ. Bruce Fields * @dir: new parent 4080146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4081146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4082146a8595SJ. Bruce Fields * 4083146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4084146a8595SJ. Bruce Fields * 4085146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4086146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4087146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4088146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4089146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4090146a8595SJ. Bruce Fields * 4091146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4092146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4093146a8595SJ. Bruce Fields * to be NFS exported. 4094146a8595SJ. Bruce Fields */ 4095146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 40961da177e4SLinus Torvalds { 40971da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 40988de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 40991da177e4SLinus Torvalds int error; 41001da177e4SLinus Torvalds 41011da177e4SLinus Torvalds if (!inode) 41021da177e4SLinus Torvalds return -ENOENT; 41031da177e4SLinus Torvalds 4104a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 41051da177e4SLinus Torvalds if (error) 41061da177e4SLinus Torvalds return error; 41071da177e4SLinus Torvalds 41081da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 41091da177e4SLinus Torvalds return -EXDEV; 41101da177e4SLinus Torvalds 41111da177e4SLinus Torvalds /* 41121da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 41131da177e4SLinus Torvalds */ 41141da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 41151da177e4SLinus Torvalds return -EPERM; 41160bd23d09SEric W. Biederman /* 41170bd23d09SEric W. Biederman * Updating the link count will likely cause i_uid and i_gid to 41180bd23d09SEric W. Biederman * be writen back improperly if their true value is unknown to 41190bd23d09SEric W. Biederman * the vfs. 41200bd23d09SEric W. Biederman */ 41210bd23d09SEric W. Biederman if (HAS_UNMAPPED_ID(inode)) 41220bd23d09SEric W. Biederman return -EPERM; 4123acfa4380SAl Viro if (!dir->i_op->link) 41241da177e4SLinus Torvalds return -EPERM; 41257e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 41261da177e4SLinus Torvalds return -EPERM; 41271da177e4SLinus Torvalds 41281da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 41291da177e4SLinus Torvalds if (error) 41301da177e4SLinus Torvalds return error; 41311da177e4SLinus Torvalds 41325955102cSAl Viro inode_lock(inode); 4133aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4134f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4135aae8a97dSAneesh Kumar K.V error = -ENOENT; 41368de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 41378de52778SAl Viro error = -EMLINK; 4138146a8595SJ. Bruce Fields else { 4139146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4140146a8595SJ. Bruce Fields if (!error) 41411da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4142146a8595SJ. Bruce Fields } 4143f4e0c30cSAl Viro 4144f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4145f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4146f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4147f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4148f4e0c30cSAl Viro } 41495955102cSAl Viro inode_unlock(inode); 4150e31e14ecSStephen Smalley if (!error) 41517e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 41521da177e4SLinus Torvalds return error; 41531da177e4SLinus Torvalds } 41544d359507SAl Viro EXPORT_SYMBOL(vfs_link); 41551da177e4SLinus Torvalds 41561da177e4SLinus Torvalds /* 41571da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 41581da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 41591da177e4SLinus Torvalds * newname. --KAB 41601da177e4SLinus Torvalds * 41611da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 41621da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 41631da177e4SLinus Torvalds * and other special files. --ADM 41641da177e4SLinus Torvalds */ 41652e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 41662e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 41671da177e4SLinus Torvalds { 41681da177e4SLinus Torvalds struct dentry *new_dentry; 4169dae6ad8fSAl Viro struct path old_path, new_path; 4170146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 417111a7b371SAneesh Kumar K.V int how = 0; 41721da177e4SLinus Torvalds int error; 41731da177e4SLinus Torvalds 417411a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4175c04030e1SUlrich Drepper return -EINVAL; 417611a7b371SAneesh Kumar K.V /* 4177f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4178f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4179f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 418011a7b371SAneesh Kumar K.V */ 4181f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4182f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4183f0cc6ffbSLinus Torvalds return -ENOENT; 418411a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4185f0cc6ffbSLinus Torvalds } 4186c04030e1SUlrich Drepper 418711a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 418811a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4189442e31caSJeff Layton retry: 419011a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 41911da177e4SLinus Torvalds if (error) 41922ad94ae6SAl Viro return error; 41932ad94ae6SAl Viro 4194442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4195442e31caSJeff Layton (how & LOOKUP_REVAL)); 41961da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 41976902d925SDave Hansen if (IS_ERR(new_dentry)) 4198dae6ad8fSAl Viro goto out; 4199dae6ad8fSAl Viro 4200dae6ad8fSAl Viro error = -EXDEV; 4201dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4202dae6ad8fSAl Viro goto out_dput; 4203800179c9SKees Cook error = may_linkat(&old_path); 4204800179c9SKees Cook if (unlikely(error)) 4205800179c9SKees Cook goto out_dput; 4206dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4207be6d3e56SKentaro Takeda if (error) 4208a8104a9fSAl Viro goto out_dput; 4209146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 421075c3f29dSDave Hansen out_dput: 4211921a1650SAl Viro done_path_create(&new_path, new_dentry); 4212146a8595SJ. Bruce Fields if (delegated_inode) { 4213146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4214d22e6338SOleg Drokin if (!error) { 4215d22e6338SOleg Drokin path_put(&old_path); 4216146a8595SJ. Bruce Fields goto retry; 4217146a8595SJ. Bruce Fields } 4218d22e6338SOleg Drokin } 4219442e31caSJeff Layton if (retry_estale(error, how)) { 4220d22e6338SOleg Drokin path_put(&old_path); 4221442e31caSJeff Layton how |= LOOKUP_REVAL; 4222442e31caSJeff Layton goto retry; 4223442e31caSJeff Layton } 42241da177e4SLinus Torvalds out: 42252d8f3038SAl Viro path_put(&old_path); 42261da177e4SLinus Torvalds 42271da177e4SLinus Torvalds return error; 42281da177e4SLinus Torvalds } 42291da177e4SLinus Torvalds 42303480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 42315590ff0dSUlrich Drepper { 4232c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 42335590ff0dSUlrich Drepper } 42345590ff0dSUlrich Drepper 4235bc27027aSMiklos Szeredi /** 4236bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4237bc27027aSMiklos Szeredi * @old_dir: parent of source 4238bc27027aSMiklos Szeredi * @old_dentry: source 4239bc27027aSMiklos Szeredi * @new_dir: parent of destination 4240bc27027aSMiklos Szeredi * @new_dentry: destination 4241bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4242520c8b16SMiklos Szeredi * @flags: rename flags 4243bc27027aSMiklos Szeredi * 4244bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4245bc27027aSMiklos Szeredi * 4246bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4247bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4248bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4249bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4250bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4251bc27027aSMiklos Szeredi * so. 4252bc27027aSMiklos Szeredi * 4253bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4254bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4255bc27027aSMiklos Szeredi * to be NFS exported. 4256bc27027aSMiklos Szeredi * 42571da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 42581da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 42591da177e4SLinus Torvalds * Problems: 4260d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 42611da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 42621da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4263a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 42641da177e4SLinus Torvalds * story. 42656cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 42666cedba89SJ. Bruce Fields * and source (if it is not a directory). 42671b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 42681da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 42691da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4270a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 42711da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 42721da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 42731da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4274a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 42751da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 42761da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 42771da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4278e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 42791b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 42801da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4281c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 42821da177e4SLinus Torvalds * locking]. 42831da177e4SLinus Torvalds */ 42841da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 42858e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4286520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 42871da177e4SLinus Torvalds { 42881da177e4SLinus Torvalds int error; 4289bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 429059b0df21SEric Paris const unsigned char *old_name; 4291bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4292bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4293da1ce067SMiklos Szeredi bool new_is_dir = false; 4294da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 42951da177e4SLinus Torvalds 42968d3e2936SMiklos Szeredi if (source == target) 42971da177e4SLinus Torvalds return 0; 42981da177e4SLinus Torvalds 42991da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 43001da177e4SLinus Torvalds if (error) 43011da177e4SLinus Torvalds return error; 43021da177e4SLinus Torvalds 4303da1ce067SMiklos Szeredi if (!target) { 4304a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4305da1ce067SMiklos Szeredi } else { 4306da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4307da1ce067SMiklos Szeredi 4308da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43091da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4310da1ce067SMiklos Szeredi else 4311da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4312da1ce067SMiklos Szeredi } 43131da177e4SLinus Torvalds if (error) 43141da177e4SLinus Torvalds return error; 43151da177e4SLinus Torvalds 43162773bf00SMiklos Szeredi if (!old_dir->i_op->rename) 43171da177e4SLinus Torvalds return -EPERM; 43181da177e4SLinus Torvalds 4319bc27027aSMiklos Szeredi /* 4320bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4321bc27027aSMiklos Szeredi * we'll need to flip '..'. 4322bc27027aSMiklos Szeredi */ 4323da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4324da1ce067SMiklos Szeredi if (is_dir) { 4325bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4326bc27027aSMiklos Szeredi if (error) 4327bc27027aSMiklos Szeredi return error; 4328bc27027aSMiklos Szeredi } 4329da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4330da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4331da1ce067SMiklos Szeredi if (error) 4332da1ce067SMiklos Szeredi return error; 4333da1ce067SMiklos Szeredi } 4334da1ce067SMiklos Szeredi } 43350eeca283SRobert Love 43360b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 43370b3974ebSMiklos Szeredi flags); 4338bc27027aSMiklos Szeredi if (error) 4339bc27027aSMiklos Szeredi return error; 4340bc27027aSMiklos Szeredi 4341bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4342bc27027aSMiklos Szeredi dget(new_dentry); 4343da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4344bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4345bc27027aSMiklos Szeredi else if (target) 43465955102cSAl Viro inode_lock(target); 4347bc27027aSMiklos Szeredi 4348bc27027aSMiklos Szeredi error = -EBUSY; 43497af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4350bc27027aSMiklos Szeredi goto out; 4351bc27027aSMiklos Szeredi 4352da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4353bc27027aSMiklos Szeredi error = -EMLINK; 4354da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4355bc27027aSMiklos Szeredi goto out; 4356da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4357da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4358da1ce067SMiklos Szeredi goto out; 4359da1ce067SMiklos Szeredi } 4360da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4361bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4362da1ce067SMiklos Szeredi if (!is_dir) { 4363bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4364bc27027aSMiklos Szeredi if (error) 4365bc27027aSMiklos Szeredi goto out; 4366da1ce067SMiklos Szeredi } 4367da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4368bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4369bc27027aSMiklos Szeredi if (error) 4370bc27027aSMiklos Szeredi goto out; 4371bc27027aSMiklos Szeredi } 4372520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4373520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4374bc27027aSMiklos Szeredi if (error) 4375bc27027aSMiklos Szeredi goto out; 4376bc27027aSMiklos Szeredi 4377da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 43781da177e4SLinus Torvalds if (is_dir) 4379bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4380bc27027aSMiklos Szeredi dont_mount(new_dentry); 43818ed936b5SEric W. Biederman detach_mounts(new_dentry); 4382bc27027aSMiklos Szeredi } 4383da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4384da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4385bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4386da1ce067SMiklos Szeredi else 4387da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4388da1ce067SMiklos Szeredi } 4389bc27027aSMiklos Szeredi out: 4390da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4391bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4392bc27027aSMiklos Szeredi else if (target) 43935955102cSAl Viro inode_unlock(target); 4394bc27027aSMiklos Szeredi dput(new_dentry); 4395da1ce067SMiklos Szeredi if (!error) { 4396123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4397da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4398da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4399da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4400da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4401da1ce067SMiklos Szeredi } 4402da1ce067SMiklos Szeredi } 44030eeca283SRobert Love fsnotify_oldname_free(old_name); 44040eeca283SRobert Love 44051da177e4SLinus Torvalds return error; 44061da177e4SLinus Torvalds } 44074d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 44081da177e4SLinus Torvalds 4409520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4410520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 44111da177e4SLinus Torvalds { 44121da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 44131da177e4SLinus Torvalds struct dentry *trap; 4414f5beed75SAl Viro struct path old_path, new_path; 4415f5beed75SAl Viro struct qstr old_last, new_last; 4416f5beed75SAl Viro int old_type, new_type; 44178e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 441891a27b2aSJeff Layton struct filename *from; 441991a27b2aSJeff Layton struct filename *to; 4420f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4421c6a94284SJeff Layton bool should_retry = false; 44222ad94ae6SAl Viro int error; 4423520c8b16SMiklos Szeredi 44240d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4425da1ce067SMiklos Szeredi return -EINVAL; 4426da1ce067SMiklos Szeredi 44270d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 44280d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4429520c8b16SMiklos Szeredi return -EINVAL; 4430520c8b16SMiklos Szeredi 44310d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 44320d7a8555SMiklos Szeredi return -EPERM; 44330d7a8555SMiklos Szeredi 4434f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4435f5beed75SAl Viro target_flags = 0; 4436f5beed75SAl Viro 4437c6a94284SJeff Layton retry: 4438c1d4dd27SAl Viro from = filename_parentat(olddfd, getname(oldname), lookup_flags, 4439c1d4dd27SAl Viro &old_path, &old_last, &old_type); 444091a27b2aSJeff Layton if (IS_ERR(from)) { 444191a27b2aSJeff Layton error = PTR_ERR(from); 44421da177e4SLinus Torvalds goto exit; 444391a27b2aSJeff Layton } 44441da177e4SLinus Torvalds 4445c1d4dd27SAl Viro to = filename_parentat(newdfd, getname(newname), lookup_flags, 4446c1d4dd27SAl Viro &new_path, &new_last, &new_type); 444791a27b2aSJeff Layton if (IS_ERR(to)) { 444891a27b2aSJeff Layton error = PTR_ERR(to); 44491da177e4SLinus Torvalds goto exit1; 445091a27b2aSJeff Layton } 44511da177e4SLinus Torvalds 44521da177e4SLinus Torvalds error = -EXDEV; 4453f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 44541da177e4SLinus Torvalds goto exit2; 44551da177e4SLinus Torvalds 44561da177e4SLinus Torvalds error = -EBUSY; 4457f5beed75SAl Viro if (old_type != LAST_NORM) 44581da177e4SLinus Torvalds goto exit2; 44591da177e4SLinus Torvalds 44600a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 44610a7c3937SMiklos Szeredi error = -EEXIST; 4462f5beed75SAl Viro if (new_type != LAST_NORM) 44631da177e4SLinus Torvalds goto exit2; 44641da177e4SLinus Torvalds 4465f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4466c30dabfeSJan Kara if (error) 4467c30dabfeSJan Kara goto exit2; 4468c30dabfeSJan Kara 44698e6d782cSJ. Bruce Fields retry_deleg: 4470f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 44711da177e4SLinus Torvalds 4472f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 44731da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 44741da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 44751da177e4SLinus Torvalds goto exit3; 44761da177e4SLinus Torvalds /* source must exist */ 44771da177e4SLinus Torvalds error = -ENOENT; 4478b18825a7SDavid Howells if (d_is_negative(old_dentry)) 44791da177e4SLinus Torvalds goto exit4; 4480f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 44811da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 44821da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 44831da177e4SLinus Torvalds goto exit4; 44840a7c3937SMiklos Szeredi error = -EEXIST; 44850a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 44860a7c3937SMiklos Szeredi goto exit5; 4487da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4488da1ce067SMiklos Szeredi error = -ENOENT; 4489da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4490da1ce067SMiklos Szeredi goto exit5; 4491da1ce067SMiklos Szeredi 4492da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4493da1ce067SMiklos Szeredi error = -ENOTDIR; 4494f5beed75SAl Viro if (new_last.name[new_last.len]) 4495da1ce067SMiklos Szeredi goto exit5; 4496da1ce067SMiklos Szeredi } 4497da1ce067SMiklos Szeredi } 44980a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 44990a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 45000a7c3937SMiklos Szeredi error = -ENOTDIR; 4501f5beed75SAl Viro if (old_last.name[old_last.len]) 45020a7c3937SMiklos Szeredi goto exit5; 4503f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 45040a7c3937SMiklos Szeredi goto exit5; 45050a7c3937SMiklos Szeredi } 45060a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 45070a7c3937SMiklos Szeredi error = -EINVAL; 45080a7c3937SMiklos Szeredi if (old_dentry == trap) 45090a7c3937SMiklos Szeredi goto exit5; 45101da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4511da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 45121da177e4SLinus Torvalds error = -ENOTEMPTY; 45131da177e4SLinus Torvalds if (new_dentry == trap) 45141da177e4SLinus Torvalds goto exit5; 45151da177e4SLinus Torvalds 4516f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4517f5beed75SAl Viro &new_path, new_dentry, flags); 4518be6d3e56SKentaro Takeda if (error) 4519c30dabfeSJan Kara goto exit5; 4520f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4521f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4522520c8b16SMiklos Szeredi &delegated_inode, flags); 45231da177e4SLinus Torvalds exit5: 45241da177e4SLinus Torvalds dput(new_dentry); 45251da177e4SLinus Torvalds exit4: 45261da177e4SLinus Torvalds dput(old_dentry); 45271da177e4SLinus Torvalds exit3: 4528f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 45298e6d782cSJ. Bruce Fields if (delegated_inode) { 45308e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 45318e6d782cSJ. Bruce Fields if (!error) 45328e6d782cSJ. Bruce Fields goto retry_deleg; 45338e6d782cSJ. Bruce Fields } 4534f5beed75SAl Viro mnt_drop_write(old_path.mnt); 45351da177e4SLinus Torvalds exit2: 4536c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4537c6a94284SJeff Layton should_retry = true; 4538f5beed75SAl Viro path_put(&new_path); 45392ad94ae6SAl Viro putname(to); 45401da177e4SLinus Torvalds exit1: 4541f5beed75SAl Viro path_put(&old_path); 45421da177e4SLinus Torvalds putname(from); 4543c6a94284SJeff Layton if (should_retry) { 4544c6a94284SJeff Layton should_retry = false; 4545c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4546c6a94284SJeff Layton goto retry; 4547c6a94284SJeff Layton } 45482ad94ae6SAl Viro exit: 45491da177e4SLinus Torvalds return error; 45501da177e4SLinus Torvalds } 45511da177e4SLinus Torvalds 4552520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4553520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4554520c8b16SMiklos Szeredi { 4555520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4556520c8b16SMiklos Szeredi } 4557520c8b16SMiklos Szeredi 4558a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 45595590ff0dSUlrich Drepper { 4560520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 45615590ff0dSUlrich Drepper } 45625590ff0dSUlrich Drepper 4563787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4564787fb6bcSMiklos Szeredi { 4565787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4566787fb6bcSMiklos Szeredi if (error) 4567787fb6bcSMiklos Szeredi return error; 4568787fb6bcSMiklos Szeredi 4569787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4570787fb6bcSMiklos Szeredi return -EPERM; 4571787fb6bcSMiklos Szeredi 4572787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4573787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4574787fb6bcSMiklos Szeredi } 4575787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4576787fb6bcSMiklos Szeredi 45775d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 45781da177e4SLinus Torvalds { 45795d826c84SAl Viro int len = PTR_ERR(link); 45801da177e4SLinus Torvalds if (IS_ERR(link)) 45811da177e4SLinus Torvalds goto out; 45821da177e4SLinus Torvalds 45831da177e4SLinus Torvalds len = strlen(link); 45841da177e4SLinus Torvalds if (len > (unsigned) buflen) 45851da177e4SLinus Torvalds len = buflen; 45861da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 45871da177e4SLinus Torvalds len = -EFAULT; 45881da177e4SLinus Torvalds out: 45891da177e4SLinus Torvalds return len; 45901da177e4SLinus Torvalds } 45911da177e4SLinus Torvalds 45921da177e4SLinus Torvalds /* 45931da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 45946b255391SAl Viro * have ->get_link() not calling nd_jump_link(). Using (or not using) it 45956b255391SAl Viro * for any given inode is up to filesystem. 45961da177e4SLinus Torvalds */ 4597d16744ecSMiklos Szeredi static int generic_readlink(struct dentry *dentry, char __user *buffer, 4598d16744ecSMiklos Szeredi int buflen) 45991da177e4SLinus Torvalds { 4600fceef393SAl Viro DEFINE_DELAYED_CALL(done); 46015f2c4179SAl Viro struct inode *inode = d_inode(dentry); 46025f2c4179SAl Viro const char *link = inode->i_link; 4603694a1764SMarcin Slusarz int res; 4604cc314eefSLinus Torvalds 4605d4dee48bSAl Viro if (!link) { 4606fceef393SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4607680baacbSAl Viro if (IS_ERR(link)) 4608680baacbSAl Viro return PTR_ERR(link); 4609d4dee48bSAl Viro } 4610680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 4611fceef393SAl Viro do_delayed_call(&done); 4612694a1764SMarcin Slusarz return res; 46131da177e4SLinus Torvalds } 46141da177e4SLinus Torvalds 4615d60874cdSMiklos Szeredi /** 4616fd4a0edfSMiklos Szeredi * vfs_readlink - copy symlink body into userspace buffer 4617fd4a0edfSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4618fd4a0edfSMiklos Szeredi * @buffer: user memory pointer 4619fd4a0edfSMiklos Szeredi * @buflen: size of buffer 4620fd4a0edfSMiklos Szeredi * 4621fd4a0edfSMiklos Szeredi * Does not touch atime. That's up to the caller if necessary 4622fd4a0edfSMiklos Szeredi * 4623fd4a0edfSMiklos Szeredi * Does not call security hook. 4624fd4a0edfSMiklos Szeredi */ 4625fd4a0edfSMiklos Szeredi int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4626fd4a0edfSMiklos Szeredi { 4627fd4a0edfSMiklos Szeredi struct inode *inode = d_inode(dentry); 4628fd4a0edfSMiklos Szeredi 462976fca90eSMiklos Szeredi if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) { 463076fca90eSMiklos Szeredi if (unlikely(inode->i_op->readlink)) 463176fca90eSMiklos Szeredi return inode->i_op->readlink(dentry, buffer, buflen); 463276fca90eSMiklos Szeredi 463376fca90eSMiklos Szeredi if (!d_is_symlink(dentry)) 4634fd4a0edfSMiklos Szeredi return -EINVAL; 4635fd4a0edfSMiklos Szeredi 463676fca90eSMiklos Szeredi spin_lock(&inode->i_lock); 463776fca90eSMiklos Szeredi inode->i_opflags |= IOP_DEFAULT_READLINK; 463876fca90eSMiklos Szeredi spin_unlock(&inode->i_lock); 463976fca90eSMiklos Szeredi } 464076fca90eSMiklos Szeredi 464176fca90eSMiklos Szeredi return generic_readlink(dentry, buffer, buflen); 4642fd4a0edfSMiklos Szeredi } 4643fd4a0edfSMiklos Szeredi EXPORT_SYMBOL(vfs_readlink); 46441da177e4SLinus Torvalds 4645d60874cdSMiklos Szeredi /** 4646d60874cdSMiklos Szeredi * vfs_get_link - get symlink body 4647d60874cdSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4648d60874cdSMiklos Szeredi * @done: caller needs to free returned data with this 4649d60874cdSMiklos Szeredi * 4650d60874cdSMiklos Szeredi * Calls security hook and i_op->get_link() on the supplied inode. 4651d60874cdSMiklos Szeredi * 4652d60874cdSMiklos Szeredi * It does not touch atime. That's up to the caller if necessary. 4653d60874cdSMiklos Szeredi * 4654d60874cdSMiklos Szeredi * Does not work on "special" symlinks like /proc/$$/fd/N 4655d60874cdSMiklos Szeredi */ 4656d60874cdSMiklos Szeredi const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done) 4657d60874cdSMiklos Szeredi { 4658d60874cdSMiklos Szeredi const char *res = ERR_PTR(-EINVAL); 4659d60874cdSMiklos Szeredi struct inode *inode = d_inode(dentry); 4660d60874cdSMiklos Szeredi 4661d60874cdSMiklos Szeredi if (d_is_symlink(dentry)) { 4662d60874cdSMiklos Szeredi res = ERR_PTR(security_inode_readlink(dentry)); 4663d60874cdSMiklos Szeredi if (!res) 4664d60874cdSMiklos Szeredi res = inode->i_op->get_link(dentry, inode, done); 4665d60874cdSMiklos Szeredi } 4666d60874cdSMiklos Szeredi return res; 4667d60874cdSMiklos Szeredi } 4668d60874cdSMiklos Szeredi EXPORT_SYMBOL(vfs_get_link); 4669d60874cdSMiklos Szeredi 46701da177e4SLinus Torvalds /* get the link contents into pagecache */ 46716b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4672fceef393SAl Viro struct delayed_call *callback) 46731da177e4SLinus Torvalds { 4674ebd09abbSDuane Griffin char *kaddr; 46751da177e4SLinus Torvalds struct page *page; 46766b255391SAl Viro struct address_space *mapping = inode->i_mapping; 46776b255391SAl Viro 4678d3883d4fSAl Viro if (!dentry) { 4679d3883d4fSAl Viro page = find_get_page(mapping, 0); 4680d3883d4fSAl Viro if (!page) 46816b255391SAl Viro return ERR_PTR(-ECHILD); 4682d3883d4fSAl Viro if (!PageUptodate(page)) { 4683d3883d4fSAl Viro put_page(page); 4684d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4685d3883d4fSAl Viro } 4686d3883d4fSAl Viro } else { 4687090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 46881da177e4SLinus Torvalds if (IS_ERR(page)) 46896fe6900eSNick Piggin return (char*)page; 4690d3883d4fSAl Viro } 4691fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 469221fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 469321fc61c7SAl Viro kaddr = page_address(page); 46946b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4695ebd09abbSDuane Griffin return kaddr; 46961da177e4SLinus Torvalds } 46971da177e4SLinus Torvalds 46986b255391SAl Viro EXPORT_SYMBOL(page_get_link); 46991da177e4SLinus Torvalds 4700fceef393SAl Viro void page_put_link(void *arg) 47011da177e4SLinus Torvalds { 4702fceef393SAl Viro put_page(arg); 47031da177e4SLinus Torvalds } 47044d359507SAl Viro EXPORT_SYMBOL(page_put_link); 47051da177e4SLinus Torvalds 4706aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4707aa80deabSAl Viro { 4708fceef393SAl Viro DEFINE_DELAYED_CALL(done); 47096b255391SAl Viro int res = readlink_copy(buffer, buflen, 47106b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4711fceef393SAl Viro &done)); 4712fceef393SAl Viro do_delayed_call(&done); 4713aa80deabSAl Viro return res; 4714aa80deabSAl Viro } 4715aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4716aa80deabSAl Viro 471754566b2cSNick Piggin /* 471854566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 471954566b2cSNick Piggin */ 472054566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 47211da177e4SLinus Torvalds { 47221da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 47230adb25d2SKirill Korotaev struct page *page; 4724afddba49SNick Piggin void *fsdata; 4725beb497abSDmitriy Monakhov int err; 472654566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 472754566b2cSNick Piggin if (nofs) 472854566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 47291da177e4SLinus Torvalds 47307e53cac4SNeilBrown retry: 4731afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 473254566b2cSNick Piggin flags, &page, &fsdata); 47331da177e4SLinus Torvalds if (err) 4734afddba49SNick Piggin goto fail; 4735afddba49SNick Piggin 473621fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4737afddba49SNick Piggin 4738afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4739afddba49SNick Piggin page, fsdata); 47401da177e4SLinus Torvalds if (err < 0) 47411da177e4SLinus Torvalds goto fail; 4742afddba49SNick Piggin if (err < len-1) 4743afddba49SNick Piggin goto retry; 4744afddba49SNick Piggin 47451da177e4SLinus Torvalds mark_inode_dirty(inode); 47461da177e4SLinus Torvalds return 0; 47471da177e4SLinus Torvalds fail: 47481da177e4SLinus Torvalds return err; 47491da177e4SLinus Torvalds } 47504d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 47511da177e4SLinus Torvalds 47520adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 47530adb25d2SKirill Korotaev { 47540adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4755c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 47560adb25d2SKirill Korotaev } 47574d359507SAl Viro EXPORT_SYMBOL(page_symlink); 47580adb25d2SKirill Korotaev 475992e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 47606b255391SAl Viro .get_link = page_get_link, 47611da177e4SLinus Torvalds }; 47621da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4763