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> 401da177e4SLinus Torvalds #include <asm/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)) 4131da177e4SLinus Torvalds return -EACCES; 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 7527973387aSAl Viro static int unlazy_link(struct nameidata *nd, struct path *link, unsigned seq) 7537973387aSAl Viro { 7547973387aSAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 7557973387aSAl Viro drop_links(nd); 7567973387aSAl Viro nd->depth = 0; 7577973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 7587973387aSAl Viro nd->path.mnt = NULL; 7597973387aSAl Viro nd->path.dentry = NULL; 7607973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7617973387aSAl Viro nd->root.mnt = NULL; 7627973387aSAl Viro rcu_read_unlock(); 7637973387aSAl Viro } else if (likely(unlazy_walk(nd, NULL, 0)) == 0) { 7647973387aSAl Viro return 0; 7657973387aSAl Viro } 7667973387aSAl Viro path_put(link); 7677973387aSAl Viro return -ECHILD; 7687973387aSAl Viro } 7697973387aSAl Viro 7704ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 77134286d66SNick Piggin { 7724ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 77334286d66SNick Piggin } 77434286d66SNick Piggin 7759f1fafeeSAl Viro /** 7769f1fafeeSAl Viro * complete_walk - successful completion of path walk 7779f1fafeeSAl Viro * @nd: pointer nameidata 77839159de2SJeff Layton * 7799f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7809f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7819f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7829f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7839f1fafeeSAl Viro * need to drop nd->path. 78439159de2SJeff Layton */ 7859f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 78639159de2SJeff Layton { 78716c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 78839159de2SJeff Layton int status; 78939159de2SJeff Layton 7909f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 7919f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7929f1fafeeSAl Viro nd->root.mnt = NULL; 7936e9918b7SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 79448a066e7SAl Viro return -ECHILD; 79548a066e7SAl Viro } 7969f1fafeeSAl Viro 79716c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 79839159de2SJeff Layton return 0; 79939159de2SJeff Layton 800ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 80116c2cd71SAl Viro return 0; 80216c2cd71SAl Viro 803ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 80439159de2SJeff Layton if (status > 0) 80539159de2SJeff Layton return 0; 80639159de2SJeff Layton 80716c2cd71SAl Viro if (!status) 80839159de2SJeff Layton status = -ESTALE; 80916c2cd71SAl Viro 81039159de2SJeff Layton return status; 81139159de2SJeff Layton } 81239159de2SJeff Layton 81318d8c860SAl Viro static void set_root(struct nameidata *nd) 8142a737871SAl Viro { 81531e6b01fSNick Piggin struct fs_struct *fs = current->fs; 8169e6697e2SAl Viro 8179e6697e2SAl Viro if (nd->flags & LOOKUP_RCU) { 8188f47a016SAl Viro unsigned seq; 819c28cc364SNick Piggin 820c28cc364SNick Piggin do { 821c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 82231e6b01fSNick Piggin nd->root = fs->root; 8238f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 824c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 8259e6697e2SAl Viro } else { 8269e6697e2SAl Viro get_fs_root(fs, &nd->root); 8279e6697e2SAl Viro } 82831e6b01fSNick Piggin } 82931e6b01fSNick Piggin 8301d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 831051d3812SIan Kent { 832051d3812SIan Kent dput(path->dentry); 8334ac91378SJan Blunck if (path->mnt != nd->path.mnt) 834051d3812SIan Kent mntput(path->mnt); 835051d3812SIan Kent } 836051d3812SIan Kent 8377b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8387b9337aaSNick Piggin struct nameidata *nd) 839051d3812SIan Kent { 84031e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8414ac91378SJan Blunck dput(nd->path.dentry); 84231e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8434ac91378SJan Blunck mntput(nd->path.mnt); 8449a229683SHuang Shijie } 84531e6b01fSNick Piggin nd->path.mnt = path->mnt; 8464ac91378SJan Blunck nd->path.dentry = path->dentry; 847051d3812SIan Kent } 848051d3812SIan Kent 849248fb5b9SAl Viro static int nd_jump_root(struct nameidata *nd) 850248fb5b9SAl Viro { 851248fb5b9SAl Viro if (nd->flags & LOOKUP_RCU) { 852248fb5b9SAl Viro struct dentry *d; 853248fb5b9SAl Viro nd->path = nd->root; 854248fb5b9SAl Viro d = nd->path.dentry; 855248fb5b9SAl Viro nd->inode = d->d_inode; 856248fb5b9SAl Viro nd->seq = nd->root_seq; 857248fb5b9SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 858248fb5b9SAl Viro return -ECHILD; 859248fb5b9SAl Viro } else { 860248fb5b9SAl Viro path_put(&nd->path); 861248fb5b9SAl Viro nd->path = nd->root; 862248fb5b9SAl Viro path_get(&nd->path); 863248fb5b9SAl Viro nd->inode = nd->path.dentry->d_inode; 864248fb5b9SAl Viro } 865248fb5b9SAl Viro nd->flags |= LOOKUP_JUMPED; 866248fb5b9SAl Viro return 0; 867248fb5b9SAl Viro } 868248fb5b9SAl Viro 869b5fb63c1SChristoph Hellwig /* 8706b255391SAl Viro * Helper to directly jump to a known parsed path from ->get_link, 871b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 872b5fb63c1SChristoph Hellwig */ 8736e77137bSAl Viro void nd_jump_link(struct path *path) 874b5fb63c1SChristoph Hellwig { 8756e77137bSAl Viro struct nameidata *nd = current->nameidata; 876b5fb63c1SChristoph Hellwig path_put(&nd->path); 877b5fb63c1SChristoph Hellwig 878b5fb63c1SChristoph Hellwig nd->path = *path; 879b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 880b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 881b5fb63c1SChristoph Hellwig } 882b5fb63c1SChristoph Hellwig 883b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 884574197e0SAl Viro { 88521c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 886fceef393SAl Viro do_delayed_call(&last->done); 8876548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 888b9ff4429SAl Viro path_put(&last->link); 889574197e0SAl Viro } 890574197e0SAl Viro 891561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 892561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 893800179c9SKees Cook 894800179c9SKees Cook /** 895800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 89655852635SRandy Dunlap * @nd: nameidata pathwalk data 897800179c9SKees Cook * 898800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 899800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 900800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 901800179c9SKees Cook * processes from failing races against path names that may change out 902800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 903800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 904800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 905800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 906800179c9SKees Cook * 907800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 908800179c9SKees Cook */ 909fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 910800179c9SKees Cook { 911800179c9SKees Cook const struct inode *inode; 912800179c9SKees Cook const struct inode *parent; 9132d7f9e2aSSeth Forshee kuid_t puid; 914800179c9SKees Cook 915800179c9SKees Cook if (!sysctl_protected_symlinks) 916800179c9SKees Cook return 0; 917800179c9SKees Cook 918800179c9SKees Cook /* Allowed if owner and follower match. */ 919fceef393SAl Viro inode = nd->link_inode; 92081abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 921800179c9SKees Cook return 0; 922800179c9SKees Cook 923800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 924aa65fa35SAl Viro parent = nd->inode; 925800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 926800179c9SKees Cook return 0; 927800179c9SKees Cook 928800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 9292d7f9e2aSSeth Forshee puid = parent->i_uid; 9302d7f9e2aSSeth Forshee if (uid_valid(puid) && uid_eq(puid, inode->i_uid)) 931800179c9SKees Cook return 0; 932800179c9SKees Cook 93331956502SAl Viro if (nd->flags & LOOKUP_RCU) 93431956502SAl Viro return -ECHILD; 93531956502SAl Viro 9361cf2665bSAl Viro audit_log_link_denied("follow_link", &nd->stack[0].link); 937800179c9SKees Cook return -EACCES; 938800179c9SKees Cook } 939800179c9SKees Cook 940800179c9SKees Cook /** 941800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 942800179c9SKees Cook * @inode: the source inode to hardlink from 943800179c9SKees Cook * 944800179c9SKees Cook * Return false if at least one of the following conditions: 945800179c9SKees Cook * - inode is not a regular file 946800179c9SKees Cook * - inode is setuid 947800179c9SKees Cook * - inode is setgid and group-exec 948800179c9SKees Cook * - access failure for read and write 949800179c9SKees Cook * 950800179c9SKees Cook * Otherwise returns true. 951800179c9SKees Cook */ 952800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 953800179c9SKees Cook { 954800179c9SKees Cook umode_t mode = inode->i_mode; 955800179c9SKees Cook 956800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 957800179c9SKees Cook if (!S_ISREG(mode)) 958800179c9SKees Cook return false; 959800179c9SKees Cook 960800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 961800179c9SKees Cook if (mode & S_ISUID) 962800179c9SKees Cook return false; 963800179c9SKees Cook 964800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 965800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 966800179c9SKees Cook return false; 967800179c9SKees Cook 968800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 969800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 970800179c9SKees Cook return false; 971800179c9SKees Cook 972800179c9SKees Cook return true; 973800179c9SKees Cook } 974800179c9SKees Cook 975800179c9SKees Cook /** 976800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 977800179c9SKees Cook * @link: the source to hardlink from 978800179c9SKees Cook * 979800179c9SKees Cook * Block hardlink when all of: 980800179c9SKees Cook * - sysctl_protected_hardlinks enabled 981800179c9SKees Cook * - fsuid does not match inode 982800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 983f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 984800179c9SKees Cook * 985800179c9SKees Cook * Returns 0 if successful, -ve on error. 986800179c9SKees Cook */ 987800179c9SKees Cook static int may_linkat(struct path *link) 988800179c9SKees Cook { 989800179c9SKees Cook struct inode *inode; 990800179c9SKees Cook 991800179c9SKees Cook if (!sysctl_protected_hardlinks) 992800179c9SKees Cook return 0; 993800179c9SKees Cook 994800179c9SKees Cook inode = link->dentry->d_inode; 995800179c9SKees Cook 996800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 997800179c9SKees Cook * otherwise, it must be a safe source. 998800179c9SKees Cook */ 999f2ca3796SDirk Steinmetz if (inode_owner_or_capable(inode) || safe_hardlink_source(inode)) 1000800179c9SKees Cook return 0; 1001800179c9SKees Cook 1002a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 1003800179c9SKees Cook return -EPERM; 1004800179c9SKees Cook } 1005800179c9SKees Cook 10063b2e7f75SAl Viro static __always_inline 10073b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 10081da177e4SLinus Torvalds { 1009ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 10101cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 1011fceef393SAl Viro struct inode *inode = nd->link_inode; 10126d7b5aaeSAl Viro int error; 10130a959df5SAl Viro const char *res; 10141da177e4SLinus Torvalds 10158fa9dd24SNeilBrown if (!(nd->flags & LOOKUP_RCU)) { 10168fa9dd24SNeilBrown touch_atime(&last->link); 10178fa9dd24SNeilBrown cond_resched(); 10188fa9dd24SNeilBrown } else if (atime_needs_update(&last->link, inode)) { 10198fa9dd24SNeilBrown if (unlikely(unlazy_walk(nd, NULL, 0))) 10208fa9dd24SNeilBrown return ERR_PTR(-ECHILD); 10218fa9dd24SNeilBrown touch_atime(&last->link); 10228fa9dd24SNeilBrown } 10238fa9dd24SNeilBrown 1024bda0be7aSNeilBrown error = security_inode_follow_link(dentry, inode, 1025bda0be7aSNeilBrown nd->flags & LOOKUP_RCU); 1026bda0be7aSNeilBrown if (unlikely(error)) 10276920a440SAl Viro return ERR_PTR(error); 102836f3b4f6SAl Viro 102986acdca1SAl Viro nd->last_type = LAST_BIND; 1030d4dee48bSAl Viro res = inode->i_link; 1031d4dee48bSAl Viro if (!res) { 1032fceef393SAl Viro const char * (*get)(struct dentry *, struct inode *, 1033fceef393SAl Viro struct delayed_call *); 1034fceef393SAl Viro get = inode->i_op->get_link; 10358c1b4566SAl Viro if (nd->flags & LOOKUP_RCU) { 1036fceef393SAl Viro res = get(NULL, inode, &last->done); 10376b255391SAl Viro if (res == ERR_PTR(-ECHILD)) { 10388c1b4566SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 10398c1b4566SAl Viro return ERR_PTR(-ECHILD); 1040fceef393SAl Viro res = get(dentry, inode, &last->done); 10418c1b4566SAl Viro } 10426b255391SAl Viro } else { 1043fceef393SAl Viro res = get(dentry, inode, &last->done); 10446b255391SAl Viro } 1045fceef393SAl Viro if (IS_ERR_OR_NULL(res)) 1046fab51e8aSAl Viro return res; 10470a959df5SAl Viro } 1048fab51e8aSAl Viro if (*res == '/') { 1049fab51e8aSAl Viro if (!nd->root.mnt) 1050fab51e8aSAl Viro set_root(nd); 1051248fb5b9SAl Viro if (unlikely(nd_jump_root(nd))) 1052fab51e8aSAl Viro return ERR_PTR(-ECHILD); 1053fab51e8aSAl Viro while (unlikely(*++res == '/')) 1054fab51e8aSAl Viro ; 1055fab51e8aSAl Viro } 1056fab51e8aSAl Viro if (!*res) 1057fab51e8aSAl Viro res = NULL; 10580a959df5SAl Viro return res; 10590a959df5SAl Viro } 10606d7b5aaeSAl Viro 1061f015f126SDavid Howells /* 1062f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1063f015f126SDavid Howells * 1064f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1065f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1066f015f126SDavid Howells * Up is towards /. 1067f015f126SDavid Howells * 1068f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1069f015f126SDavid Howells * root. 1070f015f126SDavid Howells */ 1071bab77ebfSAl Viro int follow_up(struct path *path) 10721da177e4SLinus Torvalds { 10730714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 10740714a533SAl Viro struct mount *parent; 10751da177e4SLinus Torvalds struct dentry *mountpoint; 107699b7db7bSNick Piggin 107748a066e7SAl Viro read_seqlock_excl(&mount_lock); 10780714a533SAl Viro parent = mnt->mnt_parent; 10793c0a6163SAl Viro if (parent == mnt) { 108048a066e7SAl Viro read_sequnlock_excl(&mount_lock); 10811da177e4SLinus Torvalds return 0; 10821da177e4SLinus Torvalds } 10830714a533SAl Viro mntget(&parent->mnt); 1084a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 108548a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1086bab77ebfSAl Viro dput(path->dentry); 1087bab77ebfSAl Viro path->dentry = mountpoint; 1088bab77ebfSAl Viro mntput(path->mnt); 10890714a533SAl Viro path->mnt = &parent->mnt; 10901da177e4SLinus Torvalds return 1; 10911da177e4SLinus Torvalds } 10924d359507SAl Viro EXPORT_SYMBOL(follow_up); 10931da177e4SLinus Torvalds 1094b5c84bf6SNick Piggin /* 10959875cf80SDavid Howells * Perform an automount 10969875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 10979875cf80SDavid Howells * were called with. 10981da177e4SLinus Torvalds */ 1099756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 11009875cf80SDavid Howells bool *need_mntput) 110131e6b01fSNick Piggin { 11029875cf80SDavid Howells struct vfsmount *mnt; 1103aeaa4a79SEric W. Biederman const struct cred *old_cred; 1104ea5b778aSDavid Howells int err; 11059875cf80SDavid Howells 11069875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 11079875cf80SDavid Howells return -EREMOTE; 11089875cf80SDavid Howells 11090ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 11100ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 11110ec26fd0SMiklos Szeredi * the name. 11120ec26fd0SMiklos Szeredi * 11130ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 11145a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 11150ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 11160ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 11170ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 11180ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 11195a30d8a2SDavid Howells */ 1120756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 1121d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 11225a30d8a2SDavid Howells path->dentry->d_inode) 11239875cf80SDavid Howells return -EISDIR; 11240ec26fd0SMiklos Szeredi 1125aeaa4a79SEric W. Biederman if (path->dentry->d_sb->s_user_ns != &init_user_ns) 1126aeaa4a79SEric W. Biederman return -EACCES; 1127aeaa4a79SEric W. Biederman 1128756daf26SNeilBrown nd->total_link_count++; 1129756daf26SNeilBrown if (nd->total_link_count >= 40) 11309875cf80SDavid Howells return -ELOOP; 11319875cf80SDavid Howells 1132aeaa4a79SEric W. Biederman old_cred = override_creds(&init_cred); 11339875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 1134aeaa4a79SEric W. Biederman revert_creds(old_cred); 11359875cf80SDavid Howells if (IS_ERR(mnt)) { 11369875cf80SDavid Howells /* 11379875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 11389875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 11399875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 11409875cf80SDavid Howells * 11419875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 11429875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 11439875cf80SDavid Howells * the path is inaccessible and we should say so. 11449875cf80SDavid Howells */ 1145756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 11469875cf80SDavid Howells return -EREMOTE; 11479875cf80SDavid Howells return PTR_ERR(mnt); 114831e6b01fSNick Piggin } 1149ea5b778aSDavid Howells 11509875cf80SDavid Howells if (!mnt) /* mount collision */ 11519875cf80SDavid Howells return 0; 11529875cf80SDavid Howells 11538aef1884SAl Viro if (!*need_mntput) { 11548aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 11558aef1884SAl Viro mntget(path->mnt); 11568aef1884SAl Viro *need_mntput = true; 11578aef1884SAl Viro } 115819a167afSAl Viro err = finish_automount(mnt, path); 1159ea5b778aSDavid Howells 1160ea5b778aSDavid Howells switch (err) { 1161ea5b778aSDavid Howells case -EBUSY: 1162ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 116319a167afSAl Viro return 0; 1164ea5b778aSDavid Howells case 0: 11658aef1884SAl Viro path_put(path); 11669875cf80SDavid Howells path->mnt = mnt; 11679875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 11689875cf80SDavid Howells return 0; 116919a167afSAl Viro default: 117019a167afSAl Viro return err; 11719875cf80SDavid Howells } 117219a167afSAl Viro 1173ea5b778aSDavid Howells } 11749875cf80SDavid Howells 11759875cf80SDavid Howells /* 11769875cf80SDavid Howells * Handle a dentry that is managed in some way. 1177cc53ce53SDavid Howells * - Flagged for transit management (autofs) 11789875cf80SDavid Howells * - Flagged as mountpoint 11799875cf80SDavid Howells * - Flagged as automount point 11809875cf80SDavid Howells * 11819875cf80SDavid Howells * This may only be called in refwalk mode. 11829875cf80SDavid Howells * 11839875cf80SDavid Howells * Serialization is taken care of in namespace.c 11849875cf80SDavid Howells */ 1185756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 11869875cf80SDavid Howells { 11878aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 11889875cf80SDavid Howells unsigned managed; 11899875cf80SDavid Howells bool need_mntput = false; 11908aef1884SAl Viro int ret = 0; 11919875cf80SDavid Howells 11929875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 11939875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 11949875cf80SDavid Howells * the components of that value change under us */ 11959875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 11969875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 11979875cf80SDavid Howells unlikely(managed != 0)) { 1198cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1199cc53ce53SDavid Howells * being held. */ 1200cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1201cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1202cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 12031aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1204cc53ce53SDavid Howells if (ret < 0) 12058aef1884SAl Viro break; 1206cc53ce53SDavid Howells } 1207cc53ce53SDavid Howells 12089875cf80SDavid Howells /* Transit to a mounted filesystem. */ 12099875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 12109875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12119875cf80SDavid Howells if (mounted) { 12129875cf80SDavid Howells dput(path->dentry); 12139875cf80SDavid Howells if (need_mntput) 1214463ffb2eSAl Viro mntput(path->mnt); 1215463ffb2eSAl Viro path->mnt = mounted; 1216463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 12179875cf80SDavid Howells need_mntput = true; 12189875cf80SDavid Howells continue; 1219463ffb2eSAl Viro } 1220463ffb2eSAl Viro 12219875cf80SDavid Howells /* Something is mounted on this dentry in another 12229875cf80SDavid Howells * namespace and/or whatever was mounted there in this 122348a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 122448a066e7SAl Viro * get it */ 12251da177e4SLinus Torvalds } 12269875cf80SDavid Howells 12279875cf80SDavid Howells /* Handle an automount point */ 12289875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1229756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 12309875cf80SDavid Howells if (ret < 0) 12318aef1884SAl Viro break; 12329875cf80SDavid Howells continue; 12339875cf80SDavid Howells } 12349875cf80SDavid Howells 12359875cf80SDavid Howells /* We didn't change the current path point */ 12369875cf80SDavid Howells break; 12379875cf80SDavid Howells } 12388aef1884SAl Viro 12398aef1884SAl Viro if (need_mntput && path->mnt == mnt) 12408aef1884SAl Viro mntput(path->mnt); 1241e9742b53SAl Viro if (ret == -EISDIR || !ret) 1242e9742b53SAl Viro ret = 1; 12438402752eSAl Viro if (need_mntput) 12448402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 12458402752eSAl Viro if (unlikely(ret < 0)) 12468402752eSAl Viro path_put_conditional(path, nd); 12478402752eSAl Viro return ret; 12481da177e4SLinus Torvalds } 12491da177e4SLinus Torvalds 1250cc53ce53SDavid Howells int follow_down_one(struct path *path) 12511da177e4SLinus Torvalds { 12521da177e4SLinus Torvalds struct vfsmount *mounted; 12531da177e4SLinus Torvalds 12541c755af4SAl Viro mounted = lookup_mnt(path); 12551da177e4SLinus Torvalds if (mounted) { 12569393bd07SAl Viro dput(path->dentry); 12579393bd07SAl Viro mntput(path->mnt); 12589393bd07SAl Viro path->mnt = mounted; 12599393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12601da177e4SLinus Torvalds return 1; 12611da177e4SLinus Torvalds } 12621da177e4SLinus Torvalds return 0; 12631da177e4SLinus Torvalds } 12644d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12651da177e4SLinus Torvalds 1266b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 126762a7375eSIan Kent { 1268b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1269b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 127062a7375eSIan Kent } 127162a7375eSIan Kent 12729875cf80SDavid Howells /* 1273287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1274287548e4SAl Viro * we meet a managed dentry that would need blocking. 12759875cf80SDavid Howells */ 12769875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1277254cf582SAl Viro struct inode **inode, unsigned *seqp) 12789875cf80SDavid Howells { 127962a7375eSIan Kent for (;;) { 1280c7105365SAl Viro struct mount *mounted; 128162a7375eSIan Kent /* 128262a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 128362a7375eSIan Kent * that wants to block transit. 128462a7375eSIan Kent */ 1285b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1286b8faf035SNeilBrown case -ECHILD: 1287b8faf035SNeilBrown default: 1288ab90911fSDavid Howells return false; 1289b8faf035SNeilBrown case -EISDIR: 1290b8faf035SNeilBrown return true; 1291b8faf035SNeilBrown case 0: 1292b8faf035SNeilBrown break; 1293b8faf035SNeilBrown } 129462a7375eSIan Kent 129562a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1296b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 129762a7375eSIan Kent 1298474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 12999875cf80SDavid Howells if (!mounted) 13009875cf80SDavid Howells break; 1301c7105365SAl Viro path->mnt = &mounted->mnt; 1302c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1303a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1304254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 130559430262SLinus Torvalds /* 130659430262SLinus Torvalds * Update the inode too. We don't need to re-check the 130759430262SLinus Torvalds * dentry sequence number here after this d_inode read, 130859430262SLinus Torvalds * because a mount-point is always pinned. 130959430262SLinus Torvalds */ 131059430262SLinus Torvalds *inode = path->dentry->d_inode; 13119875cf80SDavid Howells } 1312f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1313b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1314287548e4SAl Viro } 1315287548e4SAl Viro 131631e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 131731e6b01fSNick Piggin { 13184023bfc9SAl Viro struct inode *inode = nd->inode; 131931e6b01fSNick Piggin 132031e6b01fSNick Piggin while (1) { 1321aed434adSAl Viro if (path_equal(&nd->path, &nd->root)) 132231e6b01fSNick Piggin break; 132331e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 132431e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 132531e6b01fSNick Piggin struct dentry *parent = old->d_parent; 132631e6b01fSNick Piggin unsigned seq; 132731e6b01fSNick Piggin 13284023bfc9SAl Viro inode = parent->d_inode; 132931e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 1330aed434adSAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 1331aed434adSAl Viro return -ECHILD; 133231e6b01fSNick Piggin nd->path.dentry = parent; 133331e6b01fSNick Piggin nd->seq = seq; 1334397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 1335397d425dSEric W. Biederman return -ENOENT; 133631e6b01fSNick Piggin break; 1337aed434adSAl Viro } else { 1338aed434adSAl Viro struct mount *mnt = real_mount(nd->path.mnt); 1339aed434adSAl Viro struct mount *mparent = mnt->mnt_parent; 1340aed434adSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1341aed434adSAl Viro struct inode *inode2 = mountpoint->d_inode; 1342aed434adSAl Viro unsigned seq = read_seqcount_begin(&mountpoint->d_seq); 1343aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1344aed434adSAl Viro return -ECHILD; 1345aed434adSAl Viro if (&mparent->mnt == nd->path.mnt) 134631e6b01fSNick Piggin break; 1347aed434adSAl Viro /* we know that mountpoint was pinned */ 1348aed434adSAl Viro nd->path.dentry = mountpoint; 1349aed434adSAl Viro nd->path.mnt = &mparent->mnt; 1350aed434adSAl Viro inode = inode2; 1351aed434adSAl Viro nd->seq = seq; 135231e6b01fSNick Piggin } 1353aed434adSAl Viro } 1354aed434adSAl Viro while (unlikely(d_mountpoint(nd->path.dentry))) { 1355b37199e6SAl Viro struct mount *mounted; 1356b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1357aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1358aed434adSAl Viro return -ECHILD; 1359b37199e6SAl Viro if (!mounted) 1360b37199e6SAl Viro break; 1361b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1362b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 13634023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1364b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1365b37199e6SAl Viro } 13664023bfc9SAl Viro nd->inode = inode; 136731e6b01fSNick Piggin return 0; 136831e6b01fSNick Piggin } 136931e6b01fSNick Piggin 13709875cf80SDavid Howells /* 1371cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1372cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1373cc53ce53SDavid Howells * caller is permitted to proceed or not. 1374cc53ce53SDavid Howells */ 13757cc90cc3SAl Viro int follow_down(struct path *path) 1376cc53ce53SDavid Howells { 1377cc53ce53SDavid Howells unsigned managed; 1378cc53ce53SDavid Howells int ret; 1379cc53ce53SDavid Howells 1380cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1381cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1382cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1383cc53ce53SDavid Howells * being held. 1384cc53ce53SDavid Howells * 1385cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1386cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1387cc53ce53SDavid Howells * other than its daemon the right to mount on its 1388cc53ce53SDavid Howells * superstructure. 1389cc53ce53SDavid Howells * 1390cc53ce53SDavid Howells * The filesystem may sleep at this point. 1391cc53ce53SDavid Howells */ 1392cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1393cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1394cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1395ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 13961aed3e42SAl Viro path->dentry, false); 1397cc53ce53SDavid Howells if (ret < 0) 1398cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1399cc53ce53SDavid Howells } 1400cc53ce53SDavid Howells 1401cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1402cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1403cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1404cc53ce53SDavid Howells if (!mounted) 1405cc53ce53SDavid Howells break; 1406cc53ce53SDavid Howells dput(path->dentry); 1407cc53ce53SDavid Howells mntput(path->mnt); 1408cc53ce53SDavid Howells path->mnt = mounted; 1409cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1410cc53ce53SDavid Howells continue; 1411cc53ce53SDavid Howells } 1412cc53ce53SDavid Howells 1413cc53ce53SDavid Howells /* Don't handle automount points here */ 1414cc53ce53SDavid Howells break; 1415cc53ce53SDavid Howells } 1416cc53ce53SDavid Howells return 0; 1417cc53ce53SDavid Howells } 14184d359507SAl Viro EXPORT_SYMBOL(follow_down); 1419cc53ce53SDavid Howells 1420cc53ce53SDavid Howells /* 14219875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 14229875cf80SDavid Howells */ 14239875cf80SDavid Howells static void follow_mount(struct path *path) 14249875cf80SDavid Howells { 14259875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 14269875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 14279875cf80SDavid Howells if (!mounted) 14289875cf80SDavid Howells break; 14299875cf80SDavid Howells dput(path->dentry); 14309875cf80SDavid Howells mntput(path->mnt); 14319875cf80SDavid Howells path->mnt = mounted; 14329875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 14339875cf80SDavid Howells } 14349875cf80SDavid Howells } 14359875cf80SDavid Howells 1436eedf265aSEric W. Biederman static int path_parent_directory(struct path *path) 1437eedf265aSEric W. Biederman { 1438eedf265aSEric W. Biederman struct dentry *old = path->dentry; 1439eedf265aSEric W. Biederman /* rare case of legitimate dget_parent()... */ 1440eedf265aSEric W. Biederman path->dentry = dget_parent(path->dentry); 1441eedf265aSEric W. Biederman dput(old); 1442eedf265aSEric W. Biederman if (unlikely(!path_connected(path))) 1443eedf265aSEric W. Biederman return -ENOENT; 1444eedf265aSEric W. Biederman return 0; 1445eedf265aSEric W. Biederman } 1446eedf265aSEric W. Biederman 1447397d425dSEric W. Biederman static int follow_dotdot(struct nameidata *nd) 14481da177e4SLinus Torvalds { 14491da177e4SLinus Torvalds while(1) { 14502a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 14512a737871SAl Viro nd->path.mnt == nd->root.mnt) { 14521da177e4SLinus Torvalds break; 14531da177e4SLinus Torvalds } 14544ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 1455eedf265aSEric W. Biederman int ret = path_parent_directory(&nd->path); 1456eedf265aSEric W. Biederman if (ret) 1457eedf265aSEric W. Biederman return ret; 14581da177e4SLinus Torvalds break; 14591da177e4SLinus Torvalds } 14603088dd70SAl Viro if (!follow_up(&nd->path)) 14611da177e4SLinus Torvalds break; 14621da177e4SLinus Torvalds } 146379ed0226SAl Viro follow_mount(&nd->path); 146431e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 1465397d425dSEric W. Biederman return 0; 14661da177e4SLinus Torvalds } 14671da177e4SLinus Torvalds 14681da177e4SLinus Torvalds /* 1469bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1470bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1471bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1472baa03890SNick Piggin */ 1473e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1474e3c13928SAl Viro struct dentry *dir, 14756c51e513SAl Viro unsigned int flags) 1476baa03890SNick Piggin { 1477baa03890SNick Piggin struct dentry *dentry; 1478bad61189SMiklos Szeredi int error; 1479baa03890SNick Piggin 1480bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1481bad61189SMiklos Szeredi if (dentry) { 148239e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1483201f956eSAl Viro error = d_revalidate(dentry, flags); 1484bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 148574ff0ffcSAl Viro if (!error) 14865542aa2fSEric W. Biederman d_invalidate(dentry); 1487bad61189SMiklos Szeredi dput(dentry); 148874ff0ffcSAl Viro return ERR_PTR(error); 1489bad61189SMiklos Szeredi } 1490bad61189SMiklos Szeredi } 1491bad61189SMiklos Szeredi } 1492baa03890SNick Piggin return dentry; 1493baa03890SNick Piggin } 1494baa03890SNick Piggin 1495baa03890SNick Piggin /* 149613a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 149713a2c3beSJ. Bruce Fields * unhashed. 1498bad61189SMiklos Szeredi * 1499bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 150044396f4bSJosef Bacik */ 1501bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 150272bd866aSAl Viro unsigned int flags) 150344396f4bSJosef Bacik { 150444396f4bSJosef Bacik struct dentry *old; 150544396f4bSJosef Bacik 150644396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1507bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1508e188dc02SMiklos Szeredi dput(dentry); 150944396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1510e188dc02SMiklos Szeredi } 151144396f4bSJosef Bacik 151272bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 151344396f4bSJosef Bacik if (unlikely(old)) { 151444396f4bSJosef Bacik dput(dentry); 151544396f4bSJosef Bacik dentry = old; 151644396f4bSJosef Bacik } 151744396f4bSJosef Bacik return dentry; 151844396f4bSJosef Bacik } 151944396f4bSJosef Bacik 1520e3c13928SAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 152172bd866aSAl Viro struct dentry *base, unsigned int flags) 1522a3255546SAl Viro { 15236c51e513SAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 1524a3255546SAl Viro 15256c51e513SAl Viro if (dentry) 1526a3255546SAl Viro return dentry; 1527bad61189SMiklos Szeredi 15286c51e513SAl Viro dentry = d_alloc(base, name); 15296c51e513SAl Viro if (unlikely(!dentry)) 15306c51e513SAl Viro return ERR_PTR(-ENOMEM); 15316c51e513SAl Viro 153272bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1533a3255546SAl Viro } 1534a3255546SAl Viro 1535e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 1536254cf582SAl Viro struct path *path, struct inode **inode, 1537254cf582SAl Viro unsigned *seqp) 15381da177e4SLinus Torvalds { 15394ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 154031e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 15415a18fff2SAl Viro int status = 1; 15429875cf80SDavid Howells int err; 15439875cf80SDavid Howells 15443cac260aSAl Viro /* 1545b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 15465d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 15475d0f49c1SAl Viro * going to fall back to non-racy lookup. 1548b04f784eSNick Piggin */ 154931e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 155031e6b01fSNick Piggin unsigned seq; 1551766c4cbfSAl Viro bool negative; 1552da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15535d0f49c1SAl Viro if (unlikely(!dentry)) { 15545d0f49c1SAl Viro if (unlazy_walk(nd, NULL, 0)) 15555d0f49c1SAl Viro return -ECHILD; 1556e9742b53SAl Viro return 0; 15575d0f49c1SAl Viro } 15585a18fff2SAl Viro 155912f8ad4bSLinus Torvalds /* 156012f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 156112f8ad4bSLinus Torvalds * the dentry name information from lookup. 156212f8ad4bSLinus Torvalds */ 156363afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1564766c4cbfSAl Viro negative = d_is_negative(dentry); 15655d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 156612f8ad4bSLinus Torvalds return -ECHILD; 156712f8ad4bSLinus Torvalds 156812f8ad4bSLinus Torvalds /* 156912f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 157012f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 157112f8ad4bSLinus Torvalds * 157212f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 157312f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 157412f8ad4bSLinus Torvalds */ 15755d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 157631e6b01fSNick Piggin return -ECHILD; 15775a18fff2SAl Viro 1578254cf582SAl Viro *seqp = seq; 15795d0f49c1SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 15804ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15815a18fff2SAl Viro if (unlikely(status <= 0)) { 15825d0f49c1SAl Viro if (unlazy_walk(nd, dentry, seq)) 15835d0f49c1SAl Viro return -ECHILD; 15845d0f49c1SAl Viro if (status == -ECHILD) 15855d0f49c1SAl Viro status = d_revalidate(dentry, nd->flags); 15865d0f49c1SAl Viro } else { 1587daf3761cSTrond Myklebust /* 1588daf3761cSTrond Myklebust * Note: do negative dentry check after revalidation in 1589daf3761cSTrond Myklebust * case that drops it. 1590daf3761cSTrond Myklebust */ 15915d0f49c1SAl Viro if (unlikely(negative)) 1592daf3761cSTrond Myklebust return -ENOENT; 159331e6b01fSNick Piggin path->mnt = mnt; 159431e6b01fSNick Piggin path->dentry = dentry; 1595254cf582SAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 1596e9742b53SAl Viro return 1; 1597254cf582SAl Viro if (unlazy_walk(nd, dentry, seq)) 15985a18fff2SAl Viro return -ECHILD; 15995d0f49c1SAl Viro } 16005a18fff2SAl Viro } else { 1601e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 160281e6f520SAl Viro if (unlikely(!dentry)) 1603e9742b53SAl Viro return 0; 16045d0f49c1SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 16054ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 16065d0f49c1SAl Viro } 16075a18fff2SAl Viro if (unlikely(status <= 0)) { 1608e9742b53SAl Viro if (!status) 16095d0f49c1SAl Viro d_invalidate(dentry); 16105a18fff2SAl Viro dput(dentry); 16115a18fff2SAl Viro return status; 16125a18fff2SAl Viro } 1613766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1614766c4cbfSAl Viro dput(dentry); 1615766c4cbfSAl Viro return -ENOENT; 1616766c4cbfSAl Viro } 16175d0f49c1SAl Viro 16181da177e4SLinus Torvalds path->mnt = mnt; 16191da177e4SLinus Torvalds path->dentry = dentry; 1620756daf26SNeilBrown err = follow_managed(path, nd); 1621e9742b53SAl Viro if (likely(err > 0)) 162263afdfc7SDavid Howells *inode = d_backing_inode(path->dentry); 16238402752eSAl Viro return err; 1624697f514dSMiklos Szeredi } 1625697f514dSMiklos Szeredi 1626697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1627e3c13928SAl Viro static struct dentry *lookup_slow(const struct qstr *name, 1628e3c13928SAl Viro struct dentry *dir, 1629e3c13928SAl Viro unsigned int flags) 1630697f514dSMiklos Szeredi { 163194bdd655SAl Viro struct dentry *dentry = ERR_PTR(-ENOENT), *old; 16321936386eSAl Viro struct inode *inode = dir->d_inode; 1633d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 16341936386eSAl Viro 16359902af79SAl Viro inode_lock_shared(inode); 16361936386eSAl Viro /* Don't go there if it's already dead */ 163794bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 163894bdd655SAl Viro goto out; 163994bdd655SAl Viro again: 1640d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 164194bdd655SAl Viro if (IS_ERR(dentry)) 164294bdd655SAl Viro goto out; 164394bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1644949a852eSAl Viro if ((dentry->d_flags & DCACHE_OP_REVALIDATE) && 1645949a852eSAl Viro !(flags & LOOKUP_NO_REVAL)) { 1646949a852eSAl Viro int error = d_revalidate(dentry, flags); 1647949a852eSAl Viro if (unlikely(error <= 0)) { 164894bdd655SAl Viro if (!error) { 1649949a852eSAl Viro d_invalidate(dentry); 1650949a852eSAl Viro dput(dentry); 165194bdd655SAl Viro goto again; 165294bdd655SAl Viro } 165394bdd655SAl Viro dput(dentry); 1654949a852eSAl Viro dentry = ERR_PTR(error); 1655949a852eSAl Viro } 1656949a852eSAl Viro } 165794bdd655SAl Viro } else { 16581936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 165985c7f810SAl Viro d_lookup_done(dentry); 16601936386eSAl Viro if (unlikely(old)) { 16611936386eSAl Viro dput(dentry); 16621936386eSAl Viro dentry = old; 1663949a852eSAl Viro } 1664949a852eSAl Viro } 166594bdd655SAl Viro out: 16669902af79SAl Viro inode_unlock_shared(inode); 1667e3c13928SAl Viro return dentry; 16681da177e4SLinus Torvalds } 16691da177e4SLinus Torvalds 167052094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 167152094c8aSAl Viro { 167252094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16734ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 167452094c8aSAl Viro if (err != -ECHILD) 167552094c8aSAl Viro return err; 16766e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 167752094c8aSAl Viro return -ECHILD; 167852094c8aSAl Viro } 16794ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 168052094c8aSAl Viro } 168152094c8aSAl Viro 16829856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 16839856fa1bSAl Viro { 16849856fa1bSAl Viro if (type == LAST_DOTDOT) { 16859e6697e2SAl Viro if (!nd->root.mnt) 16869e6697e2SAl Viro set_root(nd); 16879856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 168870291aecSAl Viro return follow_dotdot_rcu(nd); 16899856fa1bSAl Viro } else 1690397d425dSEric W. Biederman return follow_dotdot(nd); 16919856fa1bSAl Viro } 16929856fa1bSAl Viro return 0; 16939856fa1bSAl Viro } 16949856fa1bSAl Viro 1695181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1696181548c0SAl Viro struct inode *inode, unsigned seq) 1697d63ff28fSAl Viro { 1698626de996SAl Viro int error; 16991cf2665bSAl Viro struct saved *last; 1700756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1701626de996SAl Viro path_to_nameidata(link, nd); 1702626de996SAl Viro return -ELOOP; 1703626de996SAl Viro } 1704bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1705cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1706cd179f44SAl Viro mntget(link->mnt); 17077973387aSAl Viro } 1708626de996SAl Viro error = nd_alloc_stack(nd); 1709626de996SAl Viro if (unlikely(error)) { 1710bc40aee0SAl Viro if (error == -ECHILD) { 1711bc40aee0SAl Viro if (unlikely(unlazy_link(nd, link, seq))) 1712bc40aee0SAl Viro return -ECHILD; 1713bc40aee0SAl Viro error = nd_alloc_stack(nd); 1714bc40aee0SAl Viro } 1715bc40aee0SAl Viro if (error) { 1716cd179f44SAl Viro path_put(link); 1717626de996SAl Viro return error; 1718626de996SAl Viro } 1719bc40aee0SAl Viro } 1720626de996SAl Viro 1721ab104923SAl Viro last = nd->stack + nd->depth++; 17221cf2665bSAl Viro last->link = *link; 1723fceef393SAl Viro clear_delayed_call(&last->done); 1724fceef393SAl Viro nd->link_inode = inode; 17250450b2d1SAl Viro last->seq = seq; 1726d63ff28fSAl Viro return 1; 1727d63ff28fSAl Viro } 1728d63ff28fSAl Viro 17293ddcd056SLinus Torvalds /* 17303ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 17313ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 17323ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 17333ddcd056SLinus Torvalds * for the common case. 17343ddcd056SLinus Torvalds */ 1735254cf582SAl Viro static inline int should_follow_link(struct nameidata *nd, struct path *link, 1736181548c0SAl Viro int follow, 1737181548c0SAl Viro struct inode *inode, unsigned seq) 17383ddcd056SLinus Torvalds { 1739d63ff28fSAl Viro if (likely(!d_is_symlink(link->dentry))) 1740d63ff28fSAl Viro return 0; 1741d63ff28fSAl Viro if (!follow) 1742d63ff28fSAl Viro return 0; 1743a7f77542SAl Viro /* make sure that d_is_symlink above matches inode */ 1744a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 1745a7f77542SAl Viro if (read_seqcount_retry(&link->dentry->d_seq, seq)) 1746a7f77542SAl Viro return -ECHILD; 1747a7f77542SAl Viro } 1748181548c0SAl Viro return pick_link(nd, link, inode, seq); 17493ddcd056SLinus Torvalds } 17503ddcd056SLinus Torvalds 17514693a547SAl Viro enum {WALK_GET = 1, WALK_PUT = 2}; 17524693a547SAl Viro 17534693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1754ce57dfc1SAl Viro { 1755caa85634SAl Viro struct path path; 1756ce57dfc1SAl Viro struct inode *inode; 1757254cf582SAl Viro unsigned seq; 1758ce57dfc1SAl Viro int err; 1759ce57dfc1SAl Viro /* 1760ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1761ce57dfc1SAl Viro * to be able to know about the current root directory and 1762ce57dfc1SAl Viro * parent relationships. 1763ce57dfc1SAl Viro */ 17644693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 17654693a547SAl Viro err = handle_dots(nd, nd->last_type); 17664693a547SAl Viro if (flags & WALK_PUT) 17674693a547SAl Viro put_link(nd); 17684693a547SAl Viro return err; 17694693a547SAl Viro } 1770254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1771e9742b53SAl Viro if (unlikely(err <= 0)) { 1772697f514dSMiklos Szeredi if (err < 0) 1773f0a9ba70SAl Viro return err; 1774e3c13928SAl Viro path.dentry = lookup_slow(&nd->last, nd->path.dentry, 1775e3c13928SAl Viro nd->flags); 1776e3c13928SAl Viro if (IS_ERR(path.dentry)) 1777e3c13928SAl Viro return PTR_ERR(path.dentry); 17787500c38aSAl Viro 1779e3c13928SAl Viro path.mnt = nd->path.mnt; 1780e3c13928SAl Viro err = follow_managed(&path, nd); 1781e3c13928SAl Viro if (unlikely(err < 0)) 1782f0a9ba70SAl Viro return err; 1783697f514dSMiklos Szeredi 17847500c38aSAl Viro if (unlikely(d_is_negative(path.dentry))) { 17857500c38aSAl Viro path_to_nameidata(&path, nd); 17867500c38aSAl Viro return -ENOENT; 17877500c38aSAl Viro } 17887500c38aSAl Viro 1789254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1790d4565649SAl Viro inode = d_backing_inode(path.dentry); 1791766c4cbfSAl Viro } 1792697f514dSMiklos Szeredi 17934693a547SAl Viro if (flags & WALK_PUT) 17944693a547SAl Viro put_link(nd); 1795181548c0SAl Viro err = should_follow_link(nd, &path, flags & WALK_GET, inode, seq); 1796d63ff28fSAl Viro if (unlikely(err)) 1797d63ff28fSAl Viro return err; 1798caa85634SAl Viro path_to_nameidata(&path, nd); 1799ce57dfc1SAl Viro nd->inode = inode; 1800254cf582SAl Viro nd->seq = seq; 1801ce57dfc1SAl Viro return 0; 1802ce57dfc1SAl Viro } 1803ce57dfc1SAl Viro 18041da177e4SLinus Torvalds /* 1805bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1806bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1807bfcfaa77SLinus Torvalds * 1808bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1809bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1810bfcfaa77SLinus Torvalds * fast. 1811bfcfaa77SLinus Torvalds * 1812bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1813bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1814bfcfaa77SLinus Torvalds * crossing operation. 1815bfcfaa77SLinus Torvalds * 1816bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1817bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1818bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1819bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1820bfcfaa77SLinus Torvalds */ 1821bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1822bfcfaa77SLinus Torvalds 1823f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1824bfcfaa77SLinus Torvalds 1825468a9428SGeorge Spelvin #ifdef HASH_MIX 1826bfcfaa77SLinus Torvalds 1827468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1828468a9428SGeorge Spelvin 1829468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 18302a18da7aSGeorge Spelvin /* 18312a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 18322a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 18332a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 18342a18da7aSGeorge Spelvin * and no temporaries. 18352a18da7aSGeorge Spelvin * 18362a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 18372a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 18382a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 18392a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 18402a18da7aSGeorge Spelvin * 18412a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 18422a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 18432a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 18442a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 18452a18da7aSGeorge Spelvin * 18462a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 18472a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 18482a18da7aSGeorge Spelvin * toggling any given output bit. 18492a18da7aSGeorge Spelvin * 18502a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 18512a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18522a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 18532a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 18542a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 18552a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 18562a18da7aSGeorge Spelvin * Perfect: 8192 258048 18572a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 18582a18da7aSGeorge Spelvin */ 18592a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18602a18da7aSGeorge Spelvin ( x ^= (a), \ 18612a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 18622a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 18632a18da7aSGeorge Spelvin y *= 9 ) 1864bfcfaa77SLinus Torvalds 18650fed3ac8SGeorge Spelvin /* 18662a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 18672a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 18682a18da7aSGeorge Spelvin * work done before the hash value is used. 18690fed3ac8SGeorge Spelvin */ 18702a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18710fed3ac8SGeorge Spelvin { 18722a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 18732a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 18742a18da7aSGeorge Spelvin return y >> 32; 18750fed3ac8SGeorge Spelvin } 18760fed3ac8SGeorge Spelvin 1877bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1878bfcfaa77SLinus Torvalds 18792a18da7aSGeorge Spelvin /* 18802a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 18812a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18822a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 18832a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 18842a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 18852a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 18862a18da7aSGeorge Spelvin * Perfect: 2048 31744 18872a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 18882a18da7aSGeorge Spelvin */ 18892a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18902a18da7aSGeorge Spelvin ( x ^= (a), \ 18912a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 18922a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 18932a18da7aSGeorge Spelvin y *= 9 ) 1894bfcfaa77SLinus Torvalds 18952a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18960fed3ac8SGeorge Spelvin { 18972a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 18982a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 18990fed3ac8SGeorge Spelvin } 19000fed3ac8SGeorge Spelvin 1901bfcfaa77SLinus Torvalds #endif 1902bfcfaa77SLinus Torvalds 19032a18da7aSGeorge Spelvin /* 19042a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 19052a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 19062a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 19072a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 19082a18da7aSGeorge Spelvin * finds the delimiter after the name. 19092a18da7aSGeorge Spelvin */ 1910fcfd2fbfSGeorge Spelvin unsigned int full_name_hash(const char *name, unsigned int len) 1911bfcfaa77SLinus Torvalds { 19122a18da7aSGeorge Spelvin unsigned long a, x = 0, y = 0; 1913bfcfaa77SLinus Torvalds 1914bfcfaa77SLinus Torvalds for (;;) { 1915fcfd2fbfSGeorge Spelvin if (!len) 1916fcfd2fbfSGeorge Spelvin goto done; 1917e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1918bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1919bfcfaa77SLinus Torvalds break; 19202a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1921bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1922bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1923bfcfaa77SLinus Torvalds } 19242a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 1925bfcfaa77SLinus Torvalds done: 19262a18da7aSGeorge Spelvin return fold_hash(x, y); 1927bfcfaa77SLinus Torvalds } 1928bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1929bfcfaa77SLinus Torvalds 1930fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 1931fcfd2fbfSGeorge Spelvin u64 hashlen_string(const char *name) 1932fcfd2fbfSGeorge Spelvin { 19332a18da7aSGeorge Spelvin unsigned long a = 0, x = 0, y = 0, adata, mask, len; 1934fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1935fcfd2fbfSGeorge Spelvin 1936fcfd2fbfSGeorge Spelvin len = -sizeof(unsigned long); 1937fcfd2fbfSGeorge Spelvin do { 19382a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1939fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 1940fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 1941fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 1942fcfd2fbfSGeorge Spelvin 1943fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 1944fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 19452a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 1946fcfd2fbfSGeorge Spelvin 19472a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1948fcfd2fbfSGeorge Spelvin } 1949fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 1950fcfd2fbfSGeorge Spelvin 1951bfcfaa77SLinus Torvalds /* 1952bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1953d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1954bfcfaa77SLinus Torvalds */ 1955d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1956bfcfaa77SLinus Torvalds { 19572a18da7aSGeorge Spelvin unsigned long a = 0, b, x = 0, y = 0, adata, bdata, mask, len; 195836126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1959bfcfaa77SLinus Torvalds 1960bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1961bfcfaa77SLinus Torvalds do { 19622a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1963bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1964e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 196536126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 196636126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1967bfcfaa77SLinus Torvalds 196836126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 196936126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 197036126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 19712a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 197236126f8fSLinus Torvalds 19732a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1974bfcfaa77SLinus Torvalds } 1975bfcfaa77SLinus Torvalds 19762a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 1977bfcfaa77SLinus Torvalds 1978fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 1979fcfd2fbfSGeorge Spelvin unsigned int full_name_hash(const char *name, unsigned int len) 19800145acc2SLinus Torvalds { 19810145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 19820145acc2SLinus Torvalds while (len--) 1983fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 19840145acc2SLinus Torvalds return end_name_hash(hash); 19850145acc2SLinus Torvalds } 1986ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 19870145acc2SLinus Torvalds 1988fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 1989f2a031b6SGeorge Spelvin u64 hashlen_string(const char *name) 1990fcfd2fbfSGeorge Spelvin { 1991fcfd2fbfSGeorge Spelvin unsigned long hash = init_name_hash(); 1992fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 1993fcfd2fbfSGeorge Spelvin 1994fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 1995e0ab7af9SGeorge Spelvin while (c) { 1996fcfd2fbfSGeorge Spelvin len++; 1997fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 1998fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 1999e0ab7af9SGeorge Spelvin } 2000fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 2001fcfd2fbfSGeorge Spelvin } 2002f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2003fcfd2fbfSGeorge Spelvin 20043ddcd056SLinus Torvalds /* 2005200e9ef7SLinus Torvalds * We know there's a real path component here of at least 2006200e9ef7SLinus Torvalds * one character. 2007200e9ef7SLinus Torvalds */ 2008d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 2009200e9ef7SLinus Torvalds { 2010200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 2011200e9ef7SLinus Torvalds unsigned long len = 0, c; 2012200e9ef7SLinus Torvalds 2013200e9ef7SLinus Torvalds c = (unsigned char)*name; 2014200e9ef7SLinus Torvalds do { 2015200e9ef7SLinus Torvalds len++; 2016200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2017200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2018200e9ef7SLinus Torvalds } while (c && c != '/'); 2019d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2020200e9ef7SLinus Torvalds } 2021200e9ef7SLinus Torvalds 2022bfcfaa77SLinus Torvalds #endif 2023bfcfaa77SLinus Torvalds 2024200e9ef7SLinus Torvalds /* 20251da177e4SLinus Torvalds * Name resolution. 2026ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2027ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 20281da177e4SLinus Torvalds * 2029ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2030ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 20311da177e4SLinus Torvalds */ 20326de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 20331da177e4SLinus Torvalds { 20341da177e4SLinus Torvalds int err; 20351da177e4SLinus Torvalds 20361da177e4SLinus Torvalds while (*name=='/') 20371da177e4SLinus Torvalds name++; 20381da177e4SLinus Torvalds if (!*name) 20399e18f10aSAl Viro return 0; 20401da177e4SLinus Torvalds 20411da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 20421da177e4SLinus Torvalds for(;;) { 2043d6bb3e90SLinus Torvalds u64 hash_len; 2044fe479a58SAl Viro int type; 20451da177e4SLinus Torvalds 204652094c8aSAl Viro err = may_lookup(nd); 20471da177e4SLinus Torvalds if (err) 20483595e234SAl Viro return err; 20491da177e4SLinus Torvalds 2050d6bb3e90SLinus Torvalds hash_len = hash_name(name); 20511da177e4SLinus Torvalds 2052fe479a58SAl Viro type = LAST_NORM; 2053d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2054fe479a58SAl Viro case 2: 2055200e9ef7SLinus Torvalds if (name[1] == '.') { 2056fe479a58SAl Viro type = LAST_DOTDOT; 205716c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 205816c2cd71SAl Viro } 2059fe479a58SAl Viro break; 2060fe479a58SAl Viro case 1: 2061fe479a58SAl Viro type = LAST_DOT; 2062fe479a58SAl Viro } 20635a202bcdSAl Viro if (likely(type == LAST_NORM)) { 20645a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 206516c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 20665a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2067a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2068da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 20695a202bcdSAl Viro if (err < 0) 20703595e234SAl Viro return err; 2071d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2072d6bb3e90SLinus Torvalds name = this.name; 20735a202bcdSAl Viro } 20745a202bcdSAl Viro } 2075fe479a58SAl Viro 2076d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2077d6bb3e90SLinus Torvalds nd->last.name = name; 20785f4a6a69SAl Viro nd->last_type = type; 20795f4a6a69SAl Viro 2080d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2081d6bb3e90SLinus Torvalds if (!*name) 2082bdf6cbf1SAl Viro goto OK; 2083200e9ef7SLinus Torvalds /* 2084200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2085200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2086200e9ef7SLinus Torvalds */ 2087200e9ef7SLinus Torvalds do { 2088d6bb3e90SLinus Torvalds name++; 2089d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 20908620c238SAl Viro if (unlikely(!*name)) { 20918620c238SAl Viro OK: 2092368ee9baSAl Viro /* pathname body, done */ 20938620c238SAl Viro if (!nd->depth) 20948620c238SAl Viro return 0; 20958620c238SAl Viro name = nd->stack[nd->depth - 1].name; 2096368ee9baSAl Viro /* trailing symlink, done */ 20978620c238SAl Viro if (!name) 20988620c238SAl Viro return 0; 20998620c238SAl Viro /* last component of nested symlink */ 21004693a547SAl Viro err = walk_component(nd, WALK_GET | WALK_PUT); 21018620c238SAl Viro } else { 21024693a547SAl Viro err = walk_component(nd, WALK_GET); 21038620c238SAl Viro } 2104ce57dfc1SAl Viro if (err < 0) 21053595e234SAl Viro return err; 2106fe479a58SAl Viro 2107ce57dfc1SAl Viro if (err) { 2108626de996SAl Viro const char *s = get_link(nd); 21095a460275SAl Viro 2110a1c83681SViresh Kumar if (IS_ERR(s)) 21113595e234SAl Viro return PTR_ERR(s); 2112172a39a0SAl Viro err = 0; 211312b09578SAl Viro if (unlikely(!s)) { 211412b09578SAl Viro /* jumped */ 2115b9ff4429SAl Viro put_link(nd); 211612b09578SAl Viro } else { 2117071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 211832cd7468SAl Viro name = s; 21199e18f10aSAl Viro continue; 212048c8b0c5SAl Viro } 212131e6b01fSNick Piggin } 212297242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 212397242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 212497242f99SAl Viro if (unlazy_walk(nd, NULL, 0)) 212597242f99SAl Viro return -ECHILD; 212697242f99SAl Viro } 21273595e234SAl Viro return -ENOTDIR; 21285f4a6a69SAl Viro } 2129ce57dfc1SAl Viro } 213097242f99SAl Viro } 21311da177e4SLinus Torvalds 2132c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 213331e6b01fSNick Piggin { 213431e6b01fSNick Piggin int retval = 0; 2135c8a53ee5SAl Viro const char *s = nd->name->name; 213631e6b01fSNick Piggin 213731e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 2138980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 213931e6b01fSNick Piggin nd->depth = 0; 21405b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2141b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2142b18825a7SDavid Howells struct inode *inode = root->d_inode; 2143fd2f7cb5SAl Viro if (*s) { 214444b1d530SMiklos Szeredi if (!d_can_lookup(root)) 2145368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 21465b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 21475b6ca027SAl Viro if (retval) 2148368ee9baSAl Viro return ERR_PTR(retval); 214973d049a4SAl Viro } 21505b6ca027SAl Viro nd->path = nd->root; 21515b6ca027SAl Viro nd->inode = inode; 21525b6ca027SAl Viro if (flags & LOOKUP_RCU) { 21538b61e74fSAl Viro rcu_read_lock(); 21545b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 21558f47a016SAl Viro nd->root_seq = nd->seq; 215648a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 21575b6ca027SAl Viro } else { 21585b6ca027SAl Viro path_get(&nd->path); 21595b6ca027SAl Viro } 2160368ee9baSAl Viro return s; 21615b6ca027SAl Viro } 21625b6ca027SAl Viro 216331e6b01fSNick Piggin nd->root.mnt = NULL; 2164248fb5b9SAl Viro nd->path.mnt = NULL; 2165248fb5b9SAl Viro nd->path.dentry = NULL; 216631e6b01fSNick Piggin 216748a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 2168fd2f7cb5SAl Viro if (*s == '/') { 21699e6697e2SAl Viro if (flags & LOOKUP_RCU) 21708b61e74fSAl Viro rcu_read_lock(); 2171e41f7d4eSAl Viro set_root(nd); 2172248fb5b9SAl Viro if (likely(!nd_jump_root(nd))) 2173ef55d917SAl Viro return s; 2174ef55d917SAl Viro nd->root.mnt = NULL; 2175ef55d917SAl Viro rcu_read_unlock(); 2176ef55d917SAl Viro return ERR_PTR(-ECHILD); 2177c8a53ee5SAl Viro } else if (nd->dfd == AT_FDCWD) { 2178e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 217931e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2180c28cc364SNick Piggin unsigned seq; 218131e6b01fSNick Piggin 21828b61e74fSAl Viro rcu_read_lock(); 218331e6b01fSNick Piggin 2184c28cc364SNick Piggin do { 2185c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 218631e6b01fSNick Piggin nd->path = fs->pwd; 2187ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2188c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2189c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2190e41f7d4eSAl Viro } else { 2191e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2192ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2193e41f7d4eSAl Viro } 2194ef55d917SAl Viro return s; 219531e6b01fSNick Piggin } else { 2196582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2197c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 219831e6b01fSNick Piggin struct dentry *dentry; 219931e6b01fSNick Piggin 22002903ff01SAl Viro if (!f.file) 2201368ee9baSAl Viro return ERR_PTR(-EBADF); 220231e6b01fSNick Piggin 22032903ff01SAl Viro dentry = f.file->f_path.dentry; 220431e6b01fSNick Piggin 2205fd2f7cb5SAl Viro if (*s) { 220644b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 22072903ff01SAl Viro fdput(f); 2208368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2209f52e0c11SAl Viro } 22102903ff01SAl Viro } 22112903ff01SAl Viro 22122903ff01SAl Viro nd->path = f.file->f_path; 2213e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 22148b61e74fSAl Viro rcu_read_lock(); 221534a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 221634a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22175590ff0dSUlrich Drepper } else { 22182903ff01SAl Viro path_get(&nd->path); 221934a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 22201da177e4SLinus Torvalds } 222134a26b99SAl Viro fdput(f); 2222368ee9baSAl Viro return s; 2223e41f7d4eSAl Viro } 22249b4a9b14SAl Viro } 22259b4a9b14SAl Viro 22263bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 222795fa25d9SAl Viro { 222895fa25d9SAl Viro const char *s; 2229fec2fa24SAl Viro int error = may_follow_link(nd); 2230deb106c6SAl Viro if (unlikely(error)) 22313bdba28bSAl Viro return ERR_PTR(error); 223295fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2233fab51e8aSAl Viro nd->stack[0].name = NULL; 22343b2e7f75SAl Viro s = get_link(nd); 2235deb106c6SAl Viro return s ? s : ""; 223695fa25d9SAl Viro } 223795fa25d9SAl Viro 2238caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2239bd92d7feSAl Viro { 2240bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2241bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2242bd92d7feSAl Viro 2243bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 2244deb106c6SAl Viro return walk_component(nd, 22454693a547SAl Viro nd->flags & LOOKUP_FOLLOW 22464693a547SAl Viro ? nd->depth 22474693a547SAl Viro ? WALK_PUT | WALK_GET 22484693a547SAl Viro : WALK_GET 22494693a547SAl Viro : 0); 2250bd92d7feSAl Viro } 2251bd92d7feSAl Viro 22529b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2253c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 22549b4a9b14SAl Viro { 2255c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2256bd92d7feSAl Viro int err; 225731e6b01fSNick Piggin 2258368ee9baSAl Viro if (IS_ERR(s)) 2259368ee9baSAl Viro return PTR_ERR(s); 22603bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 22613bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 22623bdba28bSAl Viro s = trailing_symlink(nd); 22633bdba28bSAl Viro if (IS_ERR(s)) { 22643bdba28bSAl Viro err = PTR_ERR(s); 22656d7b5aaeSAl Viro break; 2266bd92d7feSAl Viro } 2267bd92d7feSAl Viro } 22689f1fafeeSAl Viro if (!err) 22699f1fafeeSAl Viro err = complete_walk(nd); 2270bd92d7feSAl Viro 2271deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2272deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2273bd23a539SAl Viro err = -ENOTDIR; 2274625b6d10SAl Viro if (!err) { 2275625b6d10SAl Viro *path = nd->path; 2276625b6d10SAl Viro nd->path.mnt = NULL; 2277625b6d10SAl Viro nd->path.dentry = NULL; 2278625b6d10SAl Viro } 2279deb106c6SAl Viro terminate_walk(nd); 2280bd92d7feSAl Viro return err; 228131e6b01fSNick Piggin } 228231e6b01fSNick Piggin 2283625b6d10SAl Viro static int filename_lookup(int dfd, struct filename *name, unsigned flags, 22849ad1aaa6SAl Viro struct path *path, struct path *root) 2285873f1eedSJeff Layton { 2286894bc8c4SAl Viro int retval; 22879883d185SAl Viro struct nameidata nd; 2288abc9f5beSAl Viro if (IS_ERR(name)) 2289abc9f5beSAl Viro return PTR_ERR(name); 22909ad1aaa6SAl Viro if (unlikely(root)) { 22919ad1aaa6SAl Viro nd.root = *root; 22929ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 22939ad1aaa6SAl Viro } 22949883d185SAl Viro set_nameidata(&nd, dfd, name); 2295c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2296873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2297c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2298873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2299c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2300873f1eedSJeff Layton 2301873f1eedSJeff Layton if (likely(!retval)) 2302625b6d10SAl Viro audit_inode(name, path->dentry, flags & LOOKUP_PARENT); 23039883d185SAl Viro restore_nameidata(); 2304e4bd1c1aSAl Viro putname(name); 2305873f1eedSJeff Layton return retval; 2306873f1eedSJeff Layton } 2307873f1eedSJeff Layton 23088bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2309c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2310391172c4SAl Viro struct path *parent) 23118bcb77faSAl Viro { 2312c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2313368ee9baSAl Viro int err; 2314368ee9baSAl Viro if (IS_ERR(s)) 2315368ee9baSAl Viro return PTR_ERR(s); 2316368ee9baSAl Viro err = link_path_walk(s, nd); 23178bcb77faSAl Viro if (!err) 23188bcb77faSAl Viro err = complete_walk(nd); 2319391172c4SAl Viro if (!err) { 2320391172c4SAl Viro *parent = nd->path; 2321391172c4SAl Viro nd->path.mnt = NULL; 2322391172c4SAl Viro nd->path.dentry = NULL; 2323391172c4SAl Viro } 2324deb106c6SAl Viro terminate_walk(nd); 23258bcb77faSAl Viro return err; 23268bcb77faSAl Viro } 23278bcb77faSAl Viro 23285c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2329391172c4SAl Viro unsigned int flags, struct path *parent, 2330391172c4SAl Viro struct qstr *last, int *type) 23318bcb77faSAl Viro { 23328bcb77faSAl Viro int retval; 23339883d185SAl Viro struct nameidata nd; 23348bcb77faSAl Viro 23355c31b6ceSAl Viro if (IS_ERR(name)) 23365c31b6ceSAl Viro return name; 23379883d185SAl Viro set_nameidata(&nd, dfd, name); 2338c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 23398bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2340c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 23418bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2342c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2343391172c4SAl Viro if (likely(!retval)) { 2344391172c4SAl Viro *last = nd.last; 2345391172c4SAl Viro *type = nd.last_type; 2346391172c4SAl Viro audit_inode(name, parent->dentry, LOOKUP_PARENT); 23475c31b6ceSAl Viro } else { 23485c31b6ceSAl Viro putname(name); 23495c31b6ceSAl Viro name = ERR_PTR(retval); 2350391172c4SAl Viro } 23519883d185SAl Viro restore_nameidata(); 23525c31b6ceSAl Viro return name; 23538bcb77faSAl Viro } 23548bcb77faSAl Viro 235579714f72SAl Viro /* does lookup, returns the object with parent locked */ 235679714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 23575590ff0dSUlrich Drepper { 23585c31b6ceSAl Viro struct filename *filename; 23595c31b6ceSAl Viro struct dentry *d; 2360391172c4SAl Viro struct qstr last; 2361391172c4SAl Viro int type; 236251689104SPaul Moore 23635c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 23645c31b6ceSAl Viro &last, &type); 236551689104SPaul Moore if (IS_ERR(filename)) 236651689104SPaul Moore return ERR_CAST(filename); 23675c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2368391172c4SAl Viro path_put(path); 23695c31b6ceSAl Viro putname(filename); 23705c31b6ceSAl Viro return ERR_PTR(-EINVAL); 237179714f72SAl Viro } 23725955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2373391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 237479714f72SAl Viro if (IS_ERR(d)) { 23755955102cSAl Viro inode_unlock(path->dentry->d_inode); 2376391172c4SAl Viro path_put(path); 237779714f72SAl Viro } 237851689104SPaul Moore putname(filename); 237979714f72SAl Viro return d; 23805590ff0dSUlrich Drepper } 23815590ff0dSUlrich Drepper 2382d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2383d1811465SAl Viro { 2384abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2385abc9f5beSAl Viro flags, path, NULL); 2386d1811465SAl Viro } 23874d359507SAl Viro EXPORT_SYMBOL(kern_path); 2388d1811465SAl Viro 238916f18200SJosef 'Jeff' Sipek /** 239016f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 239116f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 239216f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 239316f18200SJosef 'Jeff' Sipek * @name: pointer to file name 239416f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2395e0a01249SAl Viro * @path: pointer to struct path to fill 239616f18200SJosef 'Jeff' Sipek */ 239716f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 239816f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2399e0a01249SAl Viro struct path *path) 240016f18200SJosef 'Jeff' Sipek { 24019ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 24029ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2403abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2404abc9f5beSAl Viro flags , path, &root); 240516f18200SJosef 'Jeff' Sipek } 24064d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 240716f18200SJosef 'Jeff' Sipek 2408eead1911SChristoph Hellwig /** 24093c9fe8cdSMiklos Szeredi * lookup_hash - lookup single pathname component on already hashed name 24103c9fe8cdSMiklos Szeredi * @name: name and hash to lookup 24113c9fe8cdSMiklos Szeredi * @base: base directory to lookup from 24123c9fe8cdSMiklos Szeredi * 24133c9fe8cdSMiklos Szeredi * The name must have been verified and hashed (see lookup_one_len()). Using 24143c9fe8cdSMiklos Szeredi * this after just full_name_hash() is unsafe. 24153c9fe8cdSMiklos Szeredi * 24163c9fe8cdSMiklos Szeredi * This function also doesn't check for search permission on base directory. 24173c9fe8cdSMiklos Szeredi * 24183c9fe8cdSMiklos Szeredi * Use lookup_one_len_unlocked() instead, unless you really know what you are 24193c9fe8cdSMiklos Szeredi * doing. 24203c9fe8cdSMiklos Szeredi * 24213c9fe8cdSMiklos Szeredi * Do not hold i_mutex; this helper takes i_mutex if necessary. 24223c9fe8cdSMiklos Szeredi */ 24233c9fe8cdSMiklos Szeredi struct dentry *lookup_hash(const struct qstr *name, struct dentry *base) 24243c9fe8cdSMiklos Szeredi { 24253c9fe8cdSMiklos Szeredi struct dentry *ret; 24263c9fe8cdSMiklos Szeredi 24273c9fe8cdSMiklos Szeredi ret = lookup_dcache(name, base, 0); 24283c9fe8cdSMiklos Szeredi if (!ret) 24293c9fe8cdSMiklos Szeredi ret = lookup_slow(name, base, 0); 24303c9fe8cdSMiklos Szeredi 24313c9fe8cdSMiklos Szeredi return ret; 24323c9fe8cdSMiklos Szeredi } 24333c9fe8cdSMiklos Szeredi EXPORT_SYMBOL(lookup_hash); 24343c9fe8cdSMiklos Szeredi 24353c9fe8cdSMiklos Szeredi /** 2436a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2437eead1911SChristoph Hellwig * @name: pathname component to lookup 2438eead1911SChristoph Hellwig * @base: base directory to lookup from 2439eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2440eead1911SChristoph Hellwig * 2441a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 24429e7543e9SAl Viro * not be called by generic code. 2443bbddca8eSNeilBrown * 2444bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2445eead1911SChristoph Hellwig */ 2446057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2447057f6c01SJames Morris { 2448057f6c01SJames Morris struct qstr this; 24496a96ba54SAl Viro unsigned int c; 2450cda309deSMiklos Szeredi int err; 2451057f6c01SJames Morris 24525955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 24532f9092e1SDavid Woodhouse 24546a96ba54SAl Viro this.name = name; 24556a96ba54SAl Viro this.len = len; 24560145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 24576a96ba54SAl Viro if (!len) 24586a96ba54SAl Viro return ERR_PTR(-EACCES); 24596a96ba54SAl Viro 246021d8a15aSAl Viro if (unlikely(name[0] == '.')) { 246121d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 246221d8a15aSAl Viro return ERR_PTR(-EACCES); 246321d8a15aSAl Viro } 246421d8a15aSAl Viro 24656a96ba54SAl Viro while (len--) { 24666a96ba54SAl Viro c = *(const unsigned char *)name++; 24676a96ba54SAl Viro if (c == '/' || c == '\0') 24686a96ba54SAl Viro return ERR_PTR(-EACCES); 24696a96ba54SAl Viro } 24705a202bcdSAl Viro /* 24715a202bcdSAl Viro * See if the low-level filesystem might want 24725a202bcdSAl Viro * to use its own hash.. 24735a202bcdSAl Viro */ 24745a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2475da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 24765a202bcdSAl Viro if (err < 0) 24775a202bcdSAl Viro return ERR_PTR(err); 24785a202bcdSAl Viro } 2479eead1911SChristoph Hellwig 2480cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2481cda309deSMiklos Szeredi if (err) 2482cda309deSMiklos Szeredi return ERR_PTR(err); 2483cda309deSMiklos Szeredi 248472bd866aSAl Viro return __lookup_hash(&this, base, 0); 2485057f6c01SJames Morris } 24864d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2487057f6c01SJames Morris 2488bbddca8eSNeilBrown /** 2489bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2490bbddca8eSNeilBrown * @name: pathname component to lookup 2491bbddca8eSNeilBrown * @base: base directory to lookup from 2492bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2493bbddca8eSNeilBrown * 2494bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2495bbddca8eSNeilBrown * not be called by generic code. 2496bbddca8eSNeilBrown * 2497bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2498bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2499bbddca8eSNeilBrown */ 2500bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2501bbddca8eSNeilBrown struct dentry *base, int len) 2502bbddca8eSNeilBrown { 2503bbddca8eSNeilBrown struct qstr this; 2504bbddca8eSNeilBrown unsigned int c; 2505bbddca8eSNeilBrown int err; 2506bbddca8eSNeilBrown 2507bbddca8eSNeilBrown this.name = name; 2508bbddca8eSNeilBrown this.len = len; 2509bbddca8eSNeilBrown this.hash = full_name_hash(name, len); 2510bbddca8eSNeilBrown if (!len) 2511bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2512bbddca8eSNeilBrown 2513bbddca8eSNeilBrown if (unlikely(name[0] == '.')) { 2514bbddca8eSNeilBrown if (len < 2 || (len == 2 && name[1] == '.')) 2515bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2516bbddca8eSNeilBrown } 2517bbddca8eSNeilBrown 2518bbddca8eSNeilBrown while (len--) { 2519bbddca8eSNeilBrown c = *(const unsigned char *)name++; 2520bbddca8eSNeilBrown if (c == '/' || c == '\0') 2521bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2522bbddca8eSNeilBrown } 2523bbddca8eSNeilBrown /* 2524bbddca8eSNeilBrown * See if the low-level filesystem might want 2525bbddca8eSNeilBrown * to use its own hash.. 2526bbddca8eSNeilBrown */ 2527bbddca8eSNeilBrown if (base->d_flags & DCACHE_OP_HASH) { 2528bbddca8eSNeilBrown int err = base->d_op->d_hash(base, &this); 2529bbddca8eSNeilBrown if (err < 0) 2530bbddca8eSNeilBrown return ERR_PTR(err); 2531bbddca8eSNeilBrown } 2532bbddca8eSNeilBrown 2533bbddca8eSNeilBrown err = inode_permission(base->d_inode, MAY_EXEC); 2534bbddca8eSNeilBrown if (err) 2535bbddca8eSNeilBrown return ERR_PTR(err); 2536bbddca8eSNeilBrown 25373c9fe8cdSMiklos Szeredi return lookup_hash(&this, base); 2538bbddca8eSNeilBrown } 2539bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2540bbddca8eSNeilBrown 2541eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2542eedf265aSEric W. Biederman int path_pts(struct path *path) 2543eedf265aSEric W. Biederman { 2544eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2545eedf265aSEric W. Biederman * the input path. 2546eedf265aSEric W. Biederman */ 2547eedf265aSEric W. Biederman struct dentry *child, *parent; 2548eedf265aSEric W. Biederman struct qstr this; 2549eedf265aSEric W. Biederman int ret; 2550eedf265aSEric W. Biederman 2551eedf265aSEric W. Biederman ret = path_parent_directory(path); 2552eedf265aSEric W. Biederman if (ret) 2553eedf265aSEric W. Biederman return ret; 2554eedf265aSEric W. Biederman 2555eedf265aSEric W. Biederman parent = path->dentry; 2556eedf265aSEric W. Biederman this.name = "pts"; 2557eedf265aSEric W. Biederman this.len = 3; 2558eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2559eedf265aSEric W. Biederman if (!child) 2560eedf265aSEric W. Biederman return -ENOENT; 2561eedf265aSEric W. Biederman 2562eedf265aSEric W. Biederman path->dentry = child; 2563eedf265aSEric W. Biederman dput(parent); 2564eedf265aSEric W. Biederman follow_mount(path); 2565eedf265aSEric W. Biederman return 0; 2566eedf265aSEric W. Biederman } 2567eedf265aSEric W. Biederman #endif 2568eedf265aSEric W. Biederman 25691fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 25701fa1e7f6SAndy Whitcroft struct path *path, int *empty) 25711da177e4SLinus Torvalds { 2572abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2573abc9f5beSAl Viro flags, path, NULL); 25741da177e4SLinus Torvalds } 2575b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 25761fa1e7f6SAndy Whitcroft 2577873f1eedSJeff Layton /* 2578873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2579873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2580873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2581873f1eedSJeff Layton * path-walking is complete. 2582873f1eedSJeff Layton */ 2583a2ec4a2dSAl Viro static inline struct filename * 2584f5beed75SAl Viro user_path_parent(int dfd, const char __user *path, 2585f5beed75SAl Viro struct path *parent, 2586f5beed75SAl Viro struct qstr *last, 2587f5beed75SAl Viro int *type, 25889e790bd6SJeff Layton unsigned int flags) 25892ad94ae6SAl Viro { 25909e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 25915c31b6ceSAl Viro return filename_parentat(dfd, getname(path), flags & LOOKUP_REVAL, 25925c31b6ceSAl Viro parent, last, type); 25932ad94ae6SAl Viro } 25942ad94ae6SAl Viro 25958033426eSJeff Layton /** 2596197df04cSAl Viro * mountpoint_last - look up last component for umount 25978033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 25988033426eSJeff Layton * @path: pointer to container for result 25998033426eSJeff Layton * 26008033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 26018033426eSJeff Layton * need to resolve the path without doing any revalidation. 26028033426eSJeff Layton * 26038033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 26048033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 26058033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 26068033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 26078033426eSJeff Layton * bogus and it doesn't exist. 26088033426eSJeff Layton * 26098033426eSJeff Layton * Returns: 26108033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 26118033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 26128033426eSJeff Layton * put in this case. 26138033426eSJeff Layton * 26148033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 26158033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 26168033426eSJeff Layton * The nd->path reference will also be put. 26178033426eSJeff Layton * 26188033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 26198033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 26208033426eSJeff Layton * to the link, and nd->path will *not* be put. 26218033426eSJeff Layton */ 26228033426eSJeff Layton static int 2623197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 26248033426eSJeff Layton { 26258033426eSJeff Layton int error = 0; 26268033426eSJeff Layton struct dentry *dentry; 26278033426eSJeff Layton struct dentry *dir = nd->path.dentry; 26288033426eSJeff Layton 262935759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 263035759521SAl Viro if (nd->flags & LOOKUP_RCU) { 26316e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 2632deb106c6SAl Viro return -ECHILD; 26338033426eSJeff Layton } 26348033426eSJeff Layton 26358033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 26368033426eSJeff Layton 26378033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 26388033426eSJeff Layton error = handle_dots(nd, nd->last_type); 263935759521SAl Viro if (error) 2640deb106c6SAl Viro return error; 26418033426eSJeff Layton dentry = dget(nd->path.dentry); 2642949a852eSAl Viro } else { 26438033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 26448033426eSJeff Layton if (!dentry) { 26458033426eSJeff Layton /* 2646949a852eSAl Viro * No cached dentry. Mounted dentries are pinned in the 2647949a852eSAl Viro * cache, so that means that this dentry is probably 2648949a852eSAl Viro * a symlink or the path doesn't actually point 2649949a852eSAl Viro * to a mounted dentry. 26508033426eSJeff Layton */ 2651949a852eSAl Viro dentry = lookup_slow(&nd->last, dir, 2652949a852eSAl Viro nd->flags | LOOKUP_NO_REVAL); 2653949a852eSAl Viro if (IS_ERR(dentry)) 2654deb106c6SAl Viro return PTR_ERR(dentry); 26558033426eSJeff Layton } 2656bcceeebaSDave Jones } 2657698934dfSDavid Howells if (d_is_negative(dentry)) { 26588033426eSJeff Layton dput(dentry); 2659deb106c6SAl Viro return -ENOENT; 266035759521SAl Viro } 2661191d7f73SAl Viro if (nd->depth) 2662191d7f73SAl Viro put_link(nd); 26638033426eSJeff Layton path->dentry = dentry; 2664295dc39dSVasily Averin path->mnt = nd->path.mnt; 2665181548c0SAl Viro error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW, 2666181548c0SAl Viro d_backing_inode(dentry), 0); 2667deb106c6SAl Viro if (unlikely(error)) 2668d63ff28fSAl Viro return error; 2669295dc39dSVasily Averin mntget(path->mnt); 26708033426eSJeff Layton follow_mount(path); 2671deb106c6SAl Viro return 0; 26728033426eSJeff Layton } 26738033426eSJeff Layton 26748033426eSJeff Layton /** 2675197df04cSAl Viro * path_mountpoint - look up a path to be umounted 26762a78b857SMasanari Iida * @nd: lookup context 26778033426eSJeff Layton * @flags: lookup flags 2678c8a53ee5SAl Viro * @path: pointer to container for result 26798033426eSJeff Layton * 26808033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2681606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 26828033426eSJeff Layton */ 26838033426eSJeff Layton static int 2684c8a53ee5SAl Viro path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) 26858033426eSJeff Layton { 2686c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2687368ee9baSAl Viro int err; 2688368ee9baSAl Viro if (IS_ERR(s)) 2689368ee9baSAl Viro return PTR_ERR(s); 26903bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 26913bdba28bSAl Viro (err = mountpoint_last(nd, path)) > 0) { 26923bdba28bSAl Viro s = trailing_symlink(nd); 26933bdba28bSAl Viro if (IS_ERR(s)) { 26943bdba28bSAl Viro err = PTR_ERR(s); 26958033426eSJeff Layton break; 26968033426eSJeff Layton } 26973bdba28bSAl Viro } 2698deb106c6SAl Viro terminate_walk(nd); 26998033426eSJeff Layton return err; 27008033426eSJeff Layton } 27018033426eSJeff Layton 27022d864651SAl Viro static int 2703668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 27042d864651SAl Viro unsigned int flags) 27052d864651SAl Viro { 27069883d185SAl Viro struct nameidata nd; 2707cbaab2dbSAl Viro int error; 2708668696dcSAl Viro if (IS_ERR(name)) 2709668696dcSAl Viro return PTR_ERR(name); 27109883d185SAl Viro set_nameidata(&nd, dfd, name); 2711c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); 27122d864651SAl Viro if (unlikely(error == -ECHILD)) 2713c8a53ee5SAl Viro error = path_mountpoint(&nd, flags, path); 27142d864651SAl Viro if (unlikely(error == -ESTALE)) 2715c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); 27162d864651SAl Viro if (likely(!error)) 2717668696dcSAl Viro audit_inode(name, path->dentry, 0); 27189883d185SAl Viro restore_nameidata(); 2719668696dcSAl Viro putname(name); 27202d864651SAl Viro return error; 27212d864651SAl Viro } 27222d864651SAl Viro 27238033426eSJeff Layton /** 2724197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 27258033426eSJeff Layton * @dfd: directory file descriptor 27268033426eSJeff Layton * @name: pathname from userland 27278033426eSJeff Layton * @flags: lookup flags 27288033426eSJeff Layton * @path: pointer to container to hold result 27298033426eSJeff Layton * 27308033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 27318033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 27328033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 27338033426eSJeff Layton * and avoid revalidating the last component. 27348033426eSJeff Layton * 27358033426eSJeff Layton * Returns 0 and populates "path" on success. 27368033426eSJeff Layton */ 27378033426eSJeff Layton int 2738197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 27398033426eSJeff Layton struct path *path) 27408033426eSJeff Layton { 2741cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 27428033426eSJeff Layton } 27438033426eSJeff Layton 27442d864651SAl Viro int 27452d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 27462d864651SAl Viro unsigned int flags) 27472d864651SAl Viro { 2748cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 27492d864651SAl Viro } 27502d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 27512d864651SAl Viro 2752cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 27531da177e4SLinus Torvalds { 27548e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2755da9592edSDavid Howells 27568e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 27571da177e4SLinus Torvalds return 0; 27588e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 27591da177e4SLinus Torvalds return 0; 276023adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 27611da177e4SLinus Torvalds } 2762cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 27631da177e4SLinus Torvalds 27641da177e4SLinus Torvalds /* 27651da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 27661da177e4SLinus Torvalds * whether the type of victim is right. 27671da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 27681da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 27691da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 27701da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 27711da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 27721da177e4SLinus Torvalds * a. be owner of dir, or 27731da177e4SLinus Torvalds * b. be owner of victim, or 27741da177e4SLinus Torvalds * c. have CAP_FOWNER capability 27751da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 27761da177e4SLinus Torvalds * links pointing to it. 27770bd23d09SEric W. Biederman * 7. If the victim has an unknown uid or gid we can't change the inode. 27780bd23d09SEric W. Biederman * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. 27790bd23d09SEric W. Biederman * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. 27800bd23d09SEric W. Biederman * 10. We can't remove a root or mountpoint. 27810bd23d09SEric W. Biederman * 11. We don't allow removal of NFS sillyrenamed files; it's handled by 27821da177e4SLinus Torvalds * nfs_async_unlink(). 27831da177e4SLinus Torvalds */ 2784b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 27851da177e4SLinus Torvalds { 278663afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 27871da177e4SLinus Torvalds int error; 27881da177e4SLinus Torvalds 2789b18825a7SDavid Howells if (d_is_negative(victim)) 27901da177e4SLinus Torvalds return -ENOENT; 2791b18825a7SDavid Howells BUG_ON(!inode); 27921da177e4SLinus Torvalds 27931da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 27944fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 27951da177e4SLinus Torvalds 2796f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 27971da177e4SLinus Torvalds if (error) 27981da177e4SLinus Torvalds return error; 27991da177e4SLinus Torvalds if (IS_APPEND(dir)) 28001da177e4SLinus Torvalds return -EPERM; 2801b18825a7SDavid Howells 2802b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 28030bd23d09SEric W. Biederman IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) 28041da177e4SLinus Torvalds return -EPERM; 28051da177e4SLinus Torvalds if (isdir) { 280644b1d530SMiklos Szeredi if (!d_is_dir(victim)) 28071da177e4SLinus Torvalds return -ENOTDIR; 28081da177e4SLinus Torvalds if (IS_ROOT(victim)) 28091da177e4SLinus Torvalds return -EBUSY; 281044b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 28111da177e4SLinus Torvalds return -EISDIR; 28121da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 28131da177e4SLinus Torvalds return -ENOENT; 28141da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 28151da177e4SLinus Torvalds return -EBUSY; 28161da177e4SLinus Torvalds return 0; 28171da177e4SLinus Torvalds } 28181da177e4SLinus Torvalds 28191da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 28201da177e4SLinus Torvalds * dir. 28211da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 28221da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 28231da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 2824036d5236SEric W. Biederman * 3. We can't do it if the fs can't represent the fsuid or fsgid. 2825036d5236SEric W. Biederman * 4. We should have write and exec permissions on dir 2826036d5236SEric W. Biederman * 5. We can't do it if dir is immutable (done in permission()) 28271da177e4SLinus Torvalds */ 2828a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 28291da177e4SLinus Torvalds { 2830036d5236SEric W. Biederman struct user_namespace *s_user_ns; 283114e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 28321da177e4SLinus Torvalds if (child->d_inode) 28331da177e4SLinus Torvalds return -EEXIST; 28341da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 28351da177e4SLinus Torvalds return -ENOENT; 2836036d5236SEric W. Biederman s_user_ns = dir->i_sb->s_user_ns; 2837036d5236SEric W. Biederman if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 2838036d5236SEric W. Biederman !kgid_has_mapping(s_user_ns, current_fsgid())) 2839036d5236SEric W. Biederman return -EOVERFLOW; 2840f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 28411da177e4SLinus Torvalds } 28421da177e4SLinus Torvalds 28431da177e4SLinus Torvalds /* 28441da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 28451da177e4SLinus Torvalds */ 28461da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 28471da177e4SLinus Torvalds { 28481da177e4SLinus Torvalds struct dentry *p; 28491da177e4SLinus Torvalds 28501da177e4SLinus Torvalds if (p1 == p2) { 28515955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28521da177e4SLinus Torvalds return NULL; 28531da177e4SLinus Torvalds } 28541da177e4SLinus Torvalds 2855fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 28561da177e4SLinus Torvalds 2857e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2858e2761a11SOGAWA Hirofumi if (p) { 28595955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 28605955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 28611da177e4SLinus Torvalds return p; 28621da177e4SLinus Torvalds } 28631da177e4SLinus Torvalds 2864e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2865e2761a11SOGAWA Hirofumi if (p) { 28665955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28675955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 28681da177e4SLinus Torvalds return p; 28691da177e4SLinus Torvalds } 28701da177e4SLinus Torvalds 28715955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28725955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 28731da177e4SLinus Torvalds return NULL; 28741da177e4SLinus Torvalds } 28754d359507SAl Viro EXPORT_SYMBOL(lock_rename); 28761da177e4SLinus Torvalds 28771da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 28781da177e4SLinus Torvalds { 28795955102cSAl Viro inode_unlock(p1->d_inode); 28801da177e4SLinus Torvalds if (p1 != p2) { 28815955102cSAl Viro inode_unlock(p2->d_inode); 2882fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 28831da177e4SLinus Torvalds } 28841da177e4SLinus Torvalds } 28854d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 28861da177e4SLinus Torvalds 28874acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2888312b63fbSAl Viro bool want_excl) 28891da177e4SLinus Torvalds { 2890a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28911da177e4SLinus Torvalds if (error) 28921da177e4SLinus Torvalds return error; 28931da177e4SLinus Torvalds 2894acfa4380SAl Viro if (!dir->i_op->create) 28951da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 28961da177e4SLinus Torvalds mode &= S_IALLUGO; 28971da177e4SLinus Torvalds mode |= S_IFREG; 28981da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 28991da177e4SLinus Torvalds if (error) 29001da177e4SLinus Torvalds return error; 2901312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2902a74574aaSStephen Smalley if (!error) 2903f38aa942SAmy Griffis fsnotify_create(dir, dentry); 29041da177e4SLinus Torvalds return error; 29051da177e4SLinus Torvalds } 29064d359507SAl Viro EXPORT_SYMBOL(vfs_create); 29071da177e4SLinus Torvalds 2908a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 2909a2982cc9SEric W. Biederman { 2910a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 2911a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 2912a2982cc9SEric W. Biederman } 2913a2982cc9SEric W. Biederman 291473d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 29151da177e4SLinus Torvalds { 29163fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 29171da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 29181da177e4SLinus Torvalds int error; 29191da177e4SLinus Torvalds 29201da177e4SLinus Torvalds if (!inode) 29211da177e4SLinus Torvalds return -ENOENT; 29221da177e4SLinus Torvalds 2923c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2924c8fe8f30SChristoph Hellwig case S_IFLNK: 29251da177e4SLinus Torvalds return -ELOOP; 2926c8fe8f30SChristoph Hellwig case S_IFDIR: 2927c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 29281da177e4SLinus Torvalds return -EISDIR; 2929c8fe8f30SChristoph Hellwig break; 2930c8fe8f30SChristoph Hellwig case S_IFBLK: 2931c8fe8f30SChristoph Hellwig case S_IFCHR: 2932a2982cc9SEric W. Biederman if (!may_open_dev(path)) 29331da177e4SLinus Torvalds return -EACCES; 2934c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2935c8fe8f30SChristoph Hellwig case S_IFIFO: 2936c8fe8f30SChristoph Hellwig case S_IFSOCK: 29371da177e4SLinus Torvalds flag &= ~O_TRUNC; 2938c8fe8f30SChristoph Hellwig break; 29394a3fd211SDave Hansen } 2940b41572e9SDave Hansen 294162fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2942b41572e9SDave Hansen if (error) 2943b41572e9SDave Hansen return error; 29446146f0d5SMimi Zohar 29451da177e4SLinus Torvalds /* 29461da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 29471da177e4SLinus Torvalds */ 29481da177e4SLinus Torvalds if (IS_APPEND(inode)) { 29498737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 29507715b521SAl Viro return -EPERM; 29511da177e4SLinus Torvalds if (flag & O_TRUNC) 29527715b521SAl Viro return -EPERM; 29531da177e4SLinus Torvalds } 29541da177e4SLinus Torvalds 29551da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 29562e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 29577715b521SAl Viro return -EPERM; 29581da177e4SLinus Torvalds 2959f3c7691eSJ. Bruce Fields return 0; 29607715b521SAl Viro } 29617715b521SAl Viro 2962e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 29637715b521SAl Viro { 2964e1181ee6SJeff Layton struct path *path = &filp->f_path; 29657715b521SAl Viro struct inode *inode = path->dentry->d_inode; 29667715b521SAl Viro int error = get_write_access(inode); 29671da177e4SLinus Torvalds if (error) 29687715b521SAl Viro return error; 29691da177e4SLinus Torvalds /* 29701da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 29711da177e4SLinus Torvalds */ 2972d7a06983SJeff Layton error = locks_verify_locked(filp); 2973be6d3e56SKentaro Takeda if (!error) 2974ea0d3ab2STetsuo Handa error = security_path_truncate(path); 29751da177e4SLinus Torvalds if (!error) { 29767715b521SAl Viro error = do_truncate(path->dentry, 0, 2977d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2978e1181ee6SJeff Layton filp); 29791da177e4SLinus Torvalds } 29801da177e4SLinus Torvalds put_write_access(inode); 2981acd0c935SMimi Zohar return error; 29821da177e4SLinus Torvalds } 29831da177e4SLinus Torvalds 2984d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2985d57999e1SDave Hansen { 29868a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 29878a5e929dSAl Viro flag--; 2988d57999e1SDave Hansen return flag; 2989d57999e1SDave Hansen } 2990d57999e1SDave Hansen 2991d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 2992d18e9008SMiklos Szeredi { 2993d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2994d18e9008SMiklos Szeredi if (error) 2995d18e9008SMiklos Szeredi return error; 2996d18e9008SMiklos Szeredi 2997d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2998d18e9008SMiklos Szeredi if (error) 2999d18e9008SMiklos Szeredi return error; 3000d18e9008SMiklos Szeredi 3001d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 3002d18e9008SMiklos Szeredi } 3003d18e9008SMiklos Szeredi 30041acf0af9SDavid Howells /* 30051acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 30061acf0af9SDavid Howells * dentry. 30071acf0af9SDavid Howells * 30081acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 30091acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 30101acf0af9SDavid Howells * 30111acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 30121acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 30131acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 30141acf0af9SDavid Howells * 30151acf0af9SDavid Howells * Returns an error code otherwise. 30161acf0af9SDavid Howells */ 30172675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 301830d90494SAl Viro struct path *path, struct file *file, 3019015c3bbcSMiklos Szeredi const struct open_flags *op, 30201643b43fSAl Viro int open_flag, umode_t mode, 302147237687SAl Viro int *opened) 3022d18e9008SMiklos Szeredi { 3023d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 3024d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 3025d18e9008SMiklos Szeredi int error; 3026d18e9008SMiklos Szeredi 3027384f26e2SAl Viro if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ 3028d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 3029d18e9008SMiklos Szeredi 3030d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 3031d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 3032d18e9008SMiklos Szeredi 303330d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 303430d90494SAl Viro file->f_path.mnt = nd->path.mnt; 30350fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 30360fb1ea09SAl Viro open_to_namei_flags(open_flag), 30370fb1ea09SAl Viro mode, opened); 30386fbd0714SAl Viro d_lookup_done(dentry); 3039384f26e2SAl Viro if (!error) { 3040d18e9008SMiklos Szeredi /* 3041384f26e2SAl Viro * We didn't have the inode before the open, so check open 3042384f26e2SAl Viro * permission here. 3043d18e9008SMiklos Szeredi */ 3044384f26e2SAl Viro int acc_mode = op->acc_mode; 304503da633aSAl Viro if (*opened & FILE_CREATED) { 304603da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 304703da633aSAl Viro fsnotify_create(dir, dentry); 304862fb4a15SAl Viro acc_mode = 0; 304903da633aSAl Viro } 30502675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 3051384f26e2SAl Viro if (WARN_ON(error > 0)) 3052384f26e2SAl Viro error = -EINVAL; 3053384f26e2SAl Viro } else if (error > 0) { 3054d18e9008SMiklos Szeredi if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 3055d18e9008SMiklos Szeredi error = -EIO; 3056384f26e2SAl Viro } else { 3057d18e9008SMiklos Szeredi if (file->f_path.dentry) { 3058d18e9008SMiklos Szeredi dput(dentry); 3059d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 306010c64ceaSAl Viro } 3061d18e9008SMiklos Szeredi if (*opened & FILE_CREATED) 3062d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 3063d18e9008SMiklos Szeredi path->dentry = dentry; 3064d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 30652675a4ebSAl Viro return 1; 3066d18e9008SMiklos Szeredi } 3067d18e9008SMiklos Szeredi } 3068d18e9008SMiklos Szeredi dput(dentry); 3069d18e9008SMiklos Szeredi return error; 3070d18e9008SMiklos Szeredi } 3071d18e9008SMiklos Szeredi 307231e6b01fSNick Piggin /* 30731acf0af9SDavid Howells * Look up and maybe create and open the last component. 3074d58ffd35SMiklos Szeredi * 3075d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 3076d58ffd35SMiklos Szeredi * 30771acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 30781acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 30791acf0af9SDavid Howells * 30801acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 30811acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 30821acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 30831acf0af9SDavid Howells * specified then a negative dentry may be returned. 30841acf0af9SDavid Howells * 30851acf0af9SDavid Howells * An error code is returned otherwise. 30861acf0af9SDavid Howells * 30871acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 30881acf0af9SDavid Howells * cleared otherwise prior to returning. 3089d58ffd35SMiklos Szeredi */ 30902675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 309130d90494SAl Viro struct file *file, 3092d58ffd35SMiklos Szeredi const struct open_flags *op, 309364894cf8SAl Viro bool got_write, int *opened) 3094d58ffd35SMiklos Szeredi { 3095d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 309654ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 30971643b43fSAl Viro int open_flag = op->open_flag; 3098d58ffd35SMiklos Szeredi struct dentry *dentry; 30991643b43fSAl Viro int error, create_error = 0; 31001643b43fSAl Viro umode_t mode = op->mode; 31016fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3102d58ffd35SMiklos Szeredi 3103ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3104ce8644fcSAl Viro return -ENOENT; 3105d58ffd35SMiklos Szeredi 310647237687SAl Viro *opened &= ~FILE_CREATED; 31076fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 31086fbd0714SAl Viro for (;;) { 31096fbd0714SAl Viro if (!dentry) { 31106fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3111d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 31122675a4ebSAl Viro return PTR_ERR(dentry); 31136fbd0714SAl Viro } 31146fbd0714SAl Viro if (d_in_lookup(dentry)) 31156fbd0714SAl Viro break; 3116d58ffd35SMiklos Szeredi 31176fbd0714SAl Viro if (!(dentry->d_flags & DCACHE_OP_REVALIDATE)) 31186fbd0714SAl Viro break; 31196fbd0714SAl Viro 31206fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 31216fbd0714SAl Viro if (likely(error > 0)) 31226fbd0714SAl Viro break; 31236fbd0714SAl Viro if (error) 31246fbd0714SAl Viro goto out_dput; 31256fbd0714SAl Viro d_invalidate(dentry); 31266fbd0714SAl Viro dput(dentry); 31276fbd0714SAl Viro dentry = NULL; 31286fbd0714SAl Viro } 31296fbd0714SAl Viro if (dentry->d_inode) { 3130d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3131d18e9008SMiklos Szeredi goto out_no_open; 31326c51e513SAl Viro } 3133d18e9008SMiklos Szeredi 31341643b43fSAl Viro /* 31351643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 31361643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 31371643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 31381643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 31391643b43fSAl Viro * 31401643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 31411643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 31421643b43fSAl Viro */ 31431643b43fSAl Viro if (open_flag & O_CREAT) { 31441643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 31451643b43fSAl Viro mode &= ~current_umask(); 31461643b43fSAl Viro if (unlikely(!got_write)) { 31471643b43fSAl Viro create_error = -EROFS; 31481643b43fSAl Viro open_flag &= ~O_CREAT; 31491643b43fSAl Viro if (open_flag & (O_EXCL | O_TRUNC)) 31501643b43fSAl Viro goto no_open; 31511643b43fSAl Viro /* No side effects, safe to clear O_CREAT */ 31521643b43fSAl Viro } else { 31531643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 31541643b43fSAl Viro if (create_error) { 31551643b43fSAl Viro open_flag &= ~O_CREAT; 31561643b43fSAl Viro if (open_flag & O_EXCL) 31571643b43fSAl Viro goto no_open; 31581643b43fSAl Viro } 31591643b43fSAl Viro } 31601643b43fSAl Viro } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && 31611643b43fSAl Viro unlikely(!got_write)) { 31621643b43fSAl Viro /* 31631643b43fSAl Viro * No O_CREATE -> atomicity not a requirement -> fall 31641643b43fSAl Viro * back to lookup + open 31651643b43fSAl Viro */ 31661643b43fSAl Viro goto no_open; 3167d18e9008SMiklos Szeredi } 3168d18e9008SMiklos Szeredi 31691643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 31701643b43fSAl Viro error = atomic_open(nd, dentry, path, file, op, open_flag, 31711643b43fSAl Viro mode, opened); 31721643b43fSAl Viro if (unlikely(error == -ENOENT) && create_error) 31731643b43fSAl Viro error = create_error; 31741643b43fSAl Viro return error; 31751643b43fSAl Viro } 317654ef4872SMiklos Szeredi 31771643b43fSAl Viro no_open: 31786fbd0714SAl Viro if (d_in_lookup(dentry)) { 317912fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 318012fa5e24SAl Viro nd->flags); 31816fbd0714SAl Viro d_lookup_done(dentry); 318212fa5e24SAl Viro if (unlikely(res)) { 318312fa5e24SAl Viro if (IS_ERR(res)) { 318412fa5e24SAl Viro error = PTR_ERR(res); 318512fa5e24SAl Viro goto out_dput; 318612fa5e24SAl Viro } 318712fa5e24SAl Viro dput(dentry); 318812fa5e24SAl Viro dentry = res; 318912fa5e24SAl Viro } 319054ef4872SMiklos Szeredi } 319154ef4872SMiklos Szeredi 3192d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 31931643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 319447237687SAl Viro *opened |= FILE_CREATED; 3195ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3196ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3197ce8644fcSAl Viro error = -EACCES; 3198d58ffd35SMiklos Szeredi goto out_dput; 319977d660a8SMiklos Szeredi } 3200ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 32011643b43fSAl Viro open_flag & O_EXCL); 3202d58ffd35SMiklos Szeredi if (error) 3203d58ffd35SMiklos Szeredi goto out_dput; 3204ce8644fcSAl Viro fsnotify_create(dir_inode, dentry); 3205d58ffd35SMiklos Szeredi } 32061643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 32071643b43fSAl Viro error = create_error; 3208d58ffd35SMiklos Szeredi goto out_dput; 3209d58ffd35SMiklos Szeredi } 3210d18e9008SMiklos Szeredi out_no_open: 3211d58ffd35SMiklos Szeredi path->dentry = dentry; 3212d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 32132675a4ebSAl Viro return 1; 3214d58ffd35SMiklos Szeredi 3215d58ffd35SMiklos Szeredi out_dput: 3216d58ffd35SMiklos Szeredi dput(dentry); 32172675a4ebSAl Viro return error; 3218d58ffd35SMiklos Szeredi } 3219d58ffd35SMiklos Szeredi 3220d58ffd35SMiklos Szeredi /* 3221fe2d35ffSAl Viro * Handle the last step of open() 322231e6b01fSNick Piggin */ 3223896475d5SAl Viro static int do_last(struct nameidata *nd, 322430d90494SAl Viro struct file *file, const struct open_flags *op, 322576ae2a5aSAl Viro int *opened) 3226fb1cc555SAl Viro { 3227a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3228ca344a89SAl Viro int open_flag = op->open_flag; 322977d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 323064894cf8SAl Viro bool got_write = false; 3231bcda7652SAl Viro int acc_mode = op->acc_mode; 3232254cf582SAl Viro unsigned seq; 3233a1eb3315SMiklos Szeredi struct inode *inode; 323416b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 3235896475d5SAl Viro struct path path; 323616b1c1cdSMiklos Szeredi bool retried = false; 323716c2cd71SAl Viro int error; 3238fb1cc555SAl Viro 3239c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3240c3e380b0SAl Viro nd->flags |= op->intent; 3241c3e380b0SAl Viro 3242bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3243fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3244deb106c6SAl Viro if (unlikely(error)) 32452675a4ebSAl Viro return error; 3246e83db167SMiklos Szeredi goto finish_open; 32471f36f774SAl Viro } 3248a2c36b45SAl Viro 3249ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3250fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3251fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3252fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3253254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 3254e9742b53SAl Viro if (likely(error > 0)) 325571574865SMiklos Szeredi goto finish_lookup; 325671574865SMiklos Szeredi 3257ce57dfc1SAl Viro if (error < 0) 3258deb106c6SAl Viro return error; 3259a1eb3315SMiklos Szeredi 326037d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 32616583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3262b6183df7SMiklos Szeredi } else { 3263fe2d35ffSAl Viro /* create side of things */ 3264a3fbbde7SAl Viro /* 3265b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3266b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3267b6183df7SMiklos Szeredi * about to look up 3268a3fbbde7SAl Viro */ 32699f1fafeeSAl Viro error = complete_walk(nd); 3270e8bb73dfSAl Viro if (error) 32712675a4ebSAl Viro return error; 3272fe2d35ffSAl Viro 327376ae2a5aSAl Viro audit_inode(nd->name, dir, LOOKUP_PARENT); 32741f36f774SAl Viro /* trailing slashes? */ 3275deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3276deb106c6SAl Viro return -EISDIR; 3277b6183df7SMiklos Szeredi } 32781f36f774SAl Viro 327916b1c1cdSMiklos Szeredi retry_lookup: 32809cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 328164894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 328264894cf8SAl Viro if (!error) 328364894cf8SAl Viro got_write = true; 328464894cf8SAl Viro /* 328564894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 328664894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 328764894cf8SAl Viro * dropping this one anyway. 328864894cf8SAl Viro */ 328964894cf8SAl Viro } 32909cf843e3SAl Viro if (open_flag & O_CREAT) 32915955102cSAl Viro inode_lock(dir->d_inode); 32929cf843e3SAl Viro else 32939cf843e3SAl Viro inode_lock_shared(dir->d_inode); 3294896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 32959cf843e3SAl Viro if (open_flag & O_CREAT) 32965955102cSAl Viro inode_unlock(dir->d_inode); 32979cf843e3SAl Viro else 32989cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3299fb1cc555SAl Viro 33002675a4ebSAl Viro if (error <= 0) { 33012675a4ebSAl Viro if (error) 3302d58ffd35SMiklos Szeredi goto out; 33036c0d46c4SAl Viro 330447237687SAl Viro if ((*opened & FILE_CREATED) || 3305496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 330677d660a8SMiklos Szeredi will_truncate = false; 3307d18e9008SMiklos Szeredi 330876ae2a5aSAl Viro audit_inode(nd->name, file->f_path.dentry, 0); 3309d18e9008SMiklos Szeredi goto opened; 3310d18e9008SMiklos Szeredi } 3311d18e9008SMiklos Szeredi 331247237687SAl Viro if (*opened & FILE_CREATED) { 33139b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3314ca344a89SAl Viro open_flag &= ~O_TRUNC; 331577d660a8SMiklos Szeredi will_truncate = false; 331662fb4a15SAl Viro acc_mode = 0; 3317896475d5SAl Viro path_to_nameidata(&path, nd); 3318e83db167SMiklos Szeredi goto finish_open_created; 3319fb1cc555SAl Viro } 3320fb1cc555SAl Viro 3321fb1cc555SAl Viro /* 3322d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3323d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3324d18e9008SMiklos Szeredi * necessary...) 3325d18e9008SMiklos Szeredi */ 332664894cf8SAl Viro if (got_write) { 3327d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 332864894cf8SAl Viro got_write = false; 3329d18e9008SMiklos Szeredi } 3330d18e9008SMiklos Szeredi 33316583fe22SAl Viro if (unlikely(d_is_negative(path.dentry))) { 33326583fe22SAl Viro path_to_nameidata(&path, nd); 33336583fe22SAl Viro return -ENOENT; 33346583fe22SAl Viro } 33356583fe22SAl Viro 33366583fe22SAl Viro /* 33376583fe22SAl Viro * create/update audit record if it already exists. 33386583fe22SAl Viro */ 33396583fe22SAl Viro audit_inode(nd->name, path.dentry, 0); 33406583fe22SAl Viro 3341deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3342deb106c6SAl Viro path_to_nameidata(&path, nd); 3343deb106c6SAl Viro return -EEXIST; 3344deb106c6SAl Viro } 3345fb1cc555SAl Viro 3346756daf26SNeilBrown error = follow_managed(&path, nd); 3347deb106c6SAl Viro if (unlikely(error < 0)) 3348deb106c6SAl Viro return error; 3349a3fbbde7SAl Viro 3350254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3351d4565649SAl Viro inode = d_backing_inode(path.dentry); 3352766c4cbfSAl Viro finish_lookup: 3353191d7f73SAl Viro if (nd->depth) 3354191d7f73SAl Viro put_link(nd); 3355181548c0SAl Viro error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW, 3356181548c0SAl Viro inode, seq); 3357deb106c6SAl Viro if (unlikely(error)) 3358d63ff28fSAl Viro return error; 3359fb1cc555SAl Viro 3360896475d5SAl Viro if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { 3361896475d5SAl Viro path_to_nameidata(&path, nd); 336216b1c1cdSMiklos Szeredi } else { 336316b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 3364896475d5SAl Viro save_parent.mnt = mntget(path.mnt); 3365896475d5SAl Viro nd->path.dentry = path.dentry; 336616b1c1cdSMiklos Szeredi 336716b1c1cdSMiklos Szeredi } 3368decf3400SMiklos Szeredi nd->inode = inode; 3369254cf582SAl Viro nd->seq = seq; 3370a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3371bc77daa7SAl Viro finish_open: 3372a3fbbde7SAl Viro error = complete_walk(nd); 337316b1c1cdSMiklos Szeredi if (error) { 337416b1c1cdSMiklos Szeredi path_put(&save_parent); 33752675a4ebSAl Viro return error; 337616b1c1cdSMiklos Szeredi } 337776ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 3378fb1cc555SAl Viro error = -EISDIR; 337944b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 33802675a4ebSAl Viro goto out; 3381af2f5542SMiklos Szeredi error = -ENOTDIR; 338244b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 33832675a4ebSAl Viro goto out; 33844bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 338577d660a8SMiklos Szeredi will_truncate = false; 33866c0d46c4SAl Viro 33870f9d1a10SAl Viro if (will_truncate) { 33880f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 33890f9d1a10SAl Viro if (error) 33902675a4ebSAl Viro goto out; 339164894cf8SAl Viro got_write = true; 33920f9d1a10SAl Viro } 3393e83db167SMiklos Szeredi finish_open_created: 3394bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3395ca344a89SAl Viro if (error) 33962675a4ebSAl Viro goto out; 33974aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 33984aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 33994aa7c634SMiklos Szeredi if (!error) { 34004aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 34014aa7c634SMiklos Szeredi } else { 340230d90494SAl Viro if (error == -EOPENSTALE) 3403f60dc3dbSMiklos Szeredi goto stale_open; 3404015c3bbcSMiklos Szeredi goto out; 3405f60dc3dbSMiklos Szeredi } 3406a8277b9bSMiklos Szeredi opened: 34072675a4ebSAl Viro error = open_check_o_direct(file); 3408fe9ec829SAl Viro if (!error) 34093034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3410fe9ec829SAl Viro if (!error && will_truncate) 34112675a4ebSAl Viro error = handle_truncate(file); 3412ca344a89SAl Viro out: 3413fe9ec829SAl Viro if (unlikely(error) && (*opened & FILE_OPENED)) 3414fe9ec829SAl Viro fput(file); 3415c80567c8SAl Viro if (unlikely(error > 0)) { 3416c80567c8SAl Viro WARN_ON(1); 3417c80567c8SAl Viro error = -EINVAL; 3418c80567c8SAl Viro } 341964894cf8SAl Viro if (got_write) 34200f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 342116b1c1cdSMiklos Szeredi path_put(&save_parent); 34222675a4ebSAl Viro return error; 3423fb1cc555SAl Viro 3424f60dc3dbSMiklos Szeredi stale_open: 3425f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3426f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3427f60dc3dbSMiklos Szeredi goto out; 3428f60dc3dbSMiklos Szeredi 3429f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3430f60dc3dbSMiklos Szeredi path_put(&nd->path); 3431f60dc3dbSMiklos Szeredi nd->path = save_parent; 3432f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3433f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3434f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 343564894cf8SAl Viro if (got_write) { 3436f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 343764894cf8SAl Viro got_write = false; 3438f60dc3dbSMiklos Szeredi } 3439f60dc3dbSMiklos Szeredi retried = true; 3440f60dc3dbSMiklos Szeredi goto retry_lookup; 3441fb1cc555SAl Viro } 3442fb1cc555SAl Viro 3443c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 344460545d0dSAl Viro const struct open_flags *op, 344560545d0dSAl Viro struct file *file, int *opened) 344660545d0dSAl Viro { 344760545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 3448625b6d10SAl Viro struct dentry *child; 344960545d0dSAl Viro struct inode *dir; 3450625b6d10SAl Viro struct path path; 3451c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 345260545d0dSAl Viro if (unlikely(error)) 345360545d0dSAl Viro return error; 3454625b6d10SAl Viro error = mnt_want_write(path.mnt); 345560545d0dSAl Viro if (unlikely(error)) 345660545d0dSAl Viro goto out; 3457625b6d10SAl Viro dir = path.dentry->d_inode; 345860545d0dSAl Viro /* we want directory to be writable */ 3459625b6d10SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 346060545d0dSAl Viro if (error) 346160545d0dSAl Viro goto out2; 346260545d0dSAl Viro if (!dir->i_op->tmpfile) { 346360545d0dSAl Viro error = -EOPNOTSUPP; 346460545d0dSAl Viro goto out2; 346560545d0dSAl Viro } 3466625b6d10SAl Viro child = d_alloc(path.dentry, &name); 346760545d0dSAl Viro if (unlikely(!child)) { 346860545d0dSAl Viro error = -ENOMEM; 346960545d0dSAl Viro goto out2; 347060545d0dSAl Viro } 3471625b6d10SAl Viro dput(path.dentry); 3472625b6d10SAl Viro path.dentry = child; 3473625b6d10SAl Viro error = dir->i_op->tmpfile(dir, child, op->mode); 347460545d0dSAl Viro if (error) 347560545d0dSAl Viro goto out2; 3476c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 347769a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 347862fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 347960545d0dSAl Viro if (error) 348060545d0dSAl Viro goto out2; 3481625b6d10SAl Viro file->f_path.mnt = path.mnt; 3482625b6d10SAl Viro error = finish_open(file, child, NULL, opened); 348360545d0dSAl Viro if (error) 348460545d0dSAl Viro goto out2; 348560545d0dSAl Viro error = open_check_o_direct(file); 3486f4e0c30cSAl Viro if (error) { 348760545d0dSAl Viro fput(file); 3488f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3489f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3490f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3491f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3492f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3493f4e0c30cSAl Viro } 349460545d0dSAl Viro out2: 3495625b6d10SAl Viro mnt_drop_write(path.mnt); 349660545d0dSAl Viro out: 3497625b6d10SAl Viro path_put(&path); 349860545d0dSAl Viro return error; 349960545d0dSAl Viro } 350060545d0dSAl Viro 35016ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 35026ac08709SAl Viro { 35036ac08709SAl Viro struct path path; 35046ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 35056ac08709SAl Viro if (!error) { 35066ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 35076ac08709SAl Viro error = vfs_open(&path, file, current_cred()); 35086ac08709SAl Viro path_put(&path); 35096ac08709SAl Viro } 35106ac08709SAl Viro return error; 35116ac08709SAl Viro } 35126ac08709SAl Viro 3513c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3514c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 35151da177e4SLinus Torvalds { 3516368ee9baSAl Viro const char *s; 351730d90494SAl Viro struct file *file; 351847237687SAl Viro int opened = 0; 351913aab428SAl Viro int error; 352031e6b01fSNick Piggin 352130d90494SAl Viro file = get_empty_filp(); 35221afc99beSAl Viro if (IS_ERR(file)) 35231afc99beSAl Viro return file; 352431e6b01fSNick Piggin 352530d90494SAl Viro file->f_flags = op->open_flag; 352631e6b01fSNick Piggin 3527bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 3528c8a53ee5SAl Viro error = do_tmpfile(nd, flags, op, file, &opened); 3529f15133dfSAl Viro goto out2; 353060545d0dSAl Viro } 353160545d0dSAl Viro 35326ac08709SAl Viro if (unlikely(file->f_flags & O_PATH)) { 35336ac08709SAl Viro error = do_o_path(nd, flags, file); 35346ac08709SAl Viro if (!error) 35356ac08709SAl Viro opened |= FILE_OPENED; 35366ac08709SAl Viro goto out2; 35376ac08709SAl Viro } 35386ac08709SAl Viro 3539c8a53ee5SAl Viro s = path_init(nd, flags); 3540368ee9baSAl Viro if (IS_ERR(s)) { 3541368ee9baSAl Viro put_filp(file); 3542368ee9baSAl Viro return ERR_CAST(s); 3543368ee9baSAl Viro } 35443bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 354576ae2a5aSAl Viro (error = do_last(nd, file, op, &opened)) > 0) { 354673d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 35473bdba28bSAl Viro s = trailing_symlink(nd); 35483bdba28bSAl Viro if (IS_ERR(s)) { 35493bdba28bSAl Viro error = PTR_ERR(s); 35502675a4ebSAl Viro break; 3551806b681cSAl Viro } 35523bdba28bSAl Viro } 3553deb106c6SAl Viro terminate_walk(nd); 3554f15133dfSAl Viro out2: 35552675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 35562675a4ebSAl Viro BUG_ON(!error); 355730d90494SAl Viro put_filp(file); 3558015c3bbcSMiklos Szeredi } 35592675a4ebSAl Viro if (unlikely(error)) { 35602675a4ebSAl Viro if (error == -EOPENSTALE) { 35612675a4ebSAl Viro if (flags & LOOKUP_RCU) 35622675a4ebSAl Viro error = -ECHILD; 35632675a4ebSAl Viro else 35642675a4ebSAl Viro error = -ESTALE; 35652675a4ebSAl Viro } 35662675a4ebSAl Viro file = ERR_PTR(error); 35672675a4ebSAl Viro } 35682675a4ebSAl Viro return file; 3569de459215SKirill Korotaev } 35701da177e4SLinus Torvalds 3571669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3572f9652e10SAl Viro const struct open_flags *op) 357313aab428SAl Viro { 35749883d185SAl Viro struct nameidata nd; 3575f9652e10SAl Viro int flags = op->lookup_flags; 357613aab428SAl Viro struct file *filp; 357713aab428SAl Viro 35789883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3579c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 358013aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3581c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 358213aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3583c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 35849883d185SAl Viro restore_nameidata(); 358513aab428SAl Viro return filp; 358613aab428SAl Viro } 358713aab428SAl Viro 358873d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3589f9652e10SAl Viro const char *name, const struct open_flags *op) 359073d049a4SAl Viro { 35919883d185SAl Viro struct nameidata nd; 359273d049a4SAl Viro struct file *file; 359351689104SPaul Moore struct filename *filename; 3594f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 359573d049a4SAl Viro 359673d049a4SAl Viro nd.root.mnt = mnt; 359773d049a4SAl Viro nd.root.dentry = dentry; 359873d049a4SAl Viro 3599b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 360073d049a4SAl Viro return ERR_PTR(-ELOOP); 360173d049a4SAl Viro 360251689104SPaul Moore filename = getname_kernel(name); 3603a1c83681SViresh Kumar if (IS_ERR(filename)) 360451689104SPaul Moore return ERR_CAST(filename); 360551689104SPaul Moore 36069883d185SAl Viro set_nameidata(&nd, -1, filename); 3607c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 360873d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3609c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 361073d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3611c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 36129883d185SAl Viro restore_nameidata(); 361351689104SPaul Moore putname(filename); 361473d049a4SAl Viro return file; 361573d049a4SAl Viro } 361673d049a4SAl Viro 3617fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 36181ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 36191da177e4SLinus Torvalds { 3620c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3621391172c4SAl Viro struct qstr last; 3622391172c4SAl Viro int type; 3623c30dabfeSJan Kara int err2; 36241ac12b4bSJeff Layton int error; 36251ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 36261ac12b4bSJeff Layton 36271ac12b4bSJeff Layton /* 36281ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 36291ac12b4bSJeff Layton * other flags passed in are ignored! 36301ac12b4bSJeff Layton */ 36311ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 36321ac12b4bSJeff Layton 36335c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 36345c31b6ceSAl Viro if (IS_ERR(name)) 36355c31b6ceSAl Viro return ERR_CAST(name); 36361da177e4SLinus Torvalds 3637c663e5d8SChristoph Hellwig /* 3638c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3639c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3640c663e5d8SChristoph Hellwig */ 36415c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3642ed75e95dSAl Viro goto out; 3643c663e5d8SChristoph Hellwig 3644c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3645391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3646c663e5d8SChristoph Hellwig /* 3647c663e5d8SChristoph Hellwig * Do the final lookup. 3648c663e5d8SChristoph Hellwig */ 3649391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 36505955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3651391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 36521da177e4SLinus Torvalds if (IS_ERR(dentry)) 3653a8104a9fSAl Viro goto unlock; 3654c663e5d8SChristoph Hellwig 3655a8104a9fSAl Viro error = -EEXIST; 3656b18825a7SDavid Howells if (d_is_positive(dentry)) 3657a8104a9fSAl Viro goto fail; 3658b18825a7SDavid Howells 3659c663e5d8SChristoph Hellwig /* 3660c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3661c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3662c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3663c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3664c663e5d8SChristoph Hellwig */ 3665391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3666a8104a9fSAl Viro error = -ENOENT; 3667ed75e95dSAl Viro goto fail; 3668e9baf6e5SAl Viro } 3669c30dabfeSJan Kara if (unlikely(err2)) { 3670c30dabfeSJan Kara error = err2; 3671a8104a9fSAl Viro goto fail; 3672c30dabfeSJan Kara } 3673181c37b6SAl Viro putname(name); 3674e9baf6e5SAl Viro return dentry; 36751da177e4SLinus Torvalds fail: 3676a8104a9fSAl Viro dput(dentry); 3677a8104a9fSAl Viro dentry = ERR_PTR(error); 3678a8104a9fSAl Viro unlock: 36795955102cSAl Viro inode_unlock(path->dentry->d_inode); 3680c30dabfeSJan Kara if (!err2) 3681391172c4SAl Viro mnt_drop_write(path->mnt); 3682ed75e95dSAl Viro out: 3683391172c4SAl Viro path_put(path); 3684181c37b6SAl Viro putname(name); 3685ed75e95dSAl Viro return dentry; 3686dae6ad8fSAl Viro } 3687fa14a0b8SAl Viro 3688fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3689fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3690fa14a0b8SAl Viro { 3691181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3692181c37b6SAl Viro path, lookup_flags); 3693fa14a0b8SAl Viro } 3694dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3695dae6ad8fSAl Viro 3696921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3697921a1650SAl Viro { 3698921a1650SAl Viro dput(dentry); 36995955102cSAl Viro inode_unlock(path->dentry->d_inode); 3700a8104a9fSAl Viro mnt_drop_write(path->mnt); 3701921a1650SAl Viro path_put(path); 3702921a1650SAl Viro } 3703921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3704921a1650SAl Viro 3705520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 37061ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3707dae6ad8fSAl Viro { 3708181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3709dae6ad8fSAl Viro } 3710dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3711dae6ad8fSAl Viro 37121a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 37131da177e4SLinus Torvalds { 3714a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 37151da177e4SLinus Torvalds 37161da177e4SLinus Torvalds if (error) 37171da177e4SLinus Torvalds return error; 37181da177e4SLinus Torvalds 3719975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 37201da177e4SLinus Torvalds return -EPERM; 37211da177e4SLinus Torvalds 3722acfa4380SAl Viro if (!dir->i_op->mknod) 37231da177e4SLinus Torvalds return -EPERM; 37241da177e4SLinus Torvalds 372508ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 372608ce5f16SSerge E. Hallyn if (error) 372708ce5f16SSerge E. Hallyn return error; 372808ce5f16SSerge E. Hallyn 37291da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 37301da177e4SLinus Torvalds if (error) 37311da177e4SLinus Torvalds return error; 37321da177e4SLinus Torvalds 37331da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3734a74574aaSStephen Smalley if (!error) 3735f38aa942SAmy Griffis fsnotify_create(dir, dentry); 37361da177e4SLinus Torvalds return error; 37371da177e4SLinus Torvalds } 37384d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 37391da177e4SLinus Torvalds 3740f69aac00SAl Viro static int may_mknod(umode_t mode) 3741463c3197SDave Hansen { 3742463c3197SDave Hansen switch (mode & S_IFMT) { 3743463c3197SDave Hansen case S_IFREG: 3744463c3197SDave Hansen case S_IFCHR: 3745463c3197SDave Hansen case S_IFBLK: 3746463c3197SDave Hansen case S_IFIFO: 3747463c3197SDave Hansen case S_IFSOCK: 3748463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3749463c3197SDave Hansen return 0; 3750463c3197SDave Hansen case S_IFDIR: 3751463c3197SDave Hansen return -EPERM; 3752463c3197SDave Hansen default: 3753463c3197SDave Hansen return -EINVAL; 3754463c3197SDave Hansen } 3755463c3197SDave Hansen } 3756463c3197SDave Hansen 37578208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 37582e4d0924SHeiko Carstens unsigned, dev) 37591da177e4SLinus Torvalds { 37601da177e4SLinus Torvalds struct dentry *dentry; 3761dae6ad8fSAl Viro struct path path; 3762dae6ad8fSAl Viro int error; 3763972567f1SJeff Layton unsigned int lookup_flags = 0; 37641da177e4SLinus Torvalds 37658e4bfca1SAl Viro error = may_mknod(mode); 37668e4bfca1SAl Viro if (error) 37678e4bfca1SAl Viro return error; 3768972567f1SJeff Layton retry: 3769972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3770dae6ad8fSAl Viro if (IS_ERR(dentry)) 3771dae6ad8fSAl Viro return PTR_ERR(dentry); 37722ad94ae6SAl Viro 3773dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3774ce3b0f8dSAl Viro mode &= ~current_umask(); 3775dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3776be6d3e56SKentaro Takeda if (error) 3777a8104a9fSAl Viro goto out; 37781da177e4SLinus Torvalds switch (mode & S_IFMT) { 37791da177e4SLinus Torvalds case 0: case S_IFREG: 3780312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 378105d1a717SMimi Zohar if (!error) 378205d1a717SMimi Zohar ima_post_path_mknod(dentry); 37831da177e4SLinus Torvalds break; 37841da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3785dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 37861da177e4SLinus Torvalds new_decode_dev(dev)); 37871da177e4SLinus Torvalds break; 37881da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3789dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 37901da177e4SLinus Torvalds break; 37911da177e4SLinus Torvalds } 3792a8104a9fSAl Viro out: 3793921a1650SAl Viro done_path_create(&path, dentry); 3794972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3795972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3796972567f1SJeff Layton goto retry; 3797972567f1SJeff Layton } 37981da177e4SLinus Torvalds return error; 37991da177e4SLinus Torvalds } 38001da177e4SLinus Torvalds 38018208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 38025590ff0dSUlrich Drepper { 38035590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 38045590ff0dSUlrich Drepper } 38055590ff0dSUlrich Drepper 380618bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 38071da177e4SLinus Torvalds { 3808a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 38098de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 38101da177e4SLinus Torvalds 38111da177e4SLinus Torvalds if (error) 38121da177e4SLinus Torvalds return error; 38131da177e4SLinus Torvalds 3814acfa4380SAl Viro if (!dir->i_op->mkdir) 38151da177e4SLinus Torvalds return -EPERM; 38161da177e4SLinus Torvalds 38171da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 38181da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 38191da177e4SLinus Torvalds if (error) 38201da177e4SLinus Torvalds return error; 38211da177e4SLinus Torvalds 38228de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 38238de52778SAl Viro return -EMLINK; 38248de52778SAl Viro 38251da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3826a74574aaSStephen Smalley if (!error) 3827f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 38281da177e4SLinus Torvalds return error; 38291da177e4SLinus Torvalds } 38304d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 38311da177e4SLinus Torvalds 3832a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 38331da177e4SLinus Torvalds { 38346902d925SDave Hansen struct dentry *dentry; 3835dae6ad8fSAl Viro struct path path; 3836dae6ad8fSAl Viro int error; 3837b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 38381da177e4SLinus Torvalds 3839b76d8b82SJeff Layton retry: 3840b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 38416902d925SDave Hansen if (IS_ERR(dentry)) 3842dae6ad8fSAl Viro return PTR_ERR(dentry); 38436902d925SDave Hansen 3844dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3845ce3b0f8dSAl Viro mode &= ~current_umask(); 3846dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3847a8104a9fSAl Viro if (!error) 3848dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3849921a1650SAl Viro done_path_create(&path, dentry); 3850b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3851b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3852b76d8b82SJeff Layton goto retry; 3853b76d8b82SJeff Layton } 38541da177e4SLinus Torvalds return error; 38551da177e4SLinus Torvalds } 38561da177e4SLinus Torvalds 3857a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 38585590ff0dSUlrich Drepper { 38595590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 38605590ff0dSUlrich Drepper } 38615590ff0dSUlrich Drepper 38621da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 38631da177e4SLinus Torvalds { 38641da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 38651da177e4SLinus Torvalds 38661da177e4SLinus Torvalds if (error) 38671da177e4SLinus Torvalds return error; 38681da177e4SLinus Torvalds 3869acfa4380SAl Viro if (!dir->i_op->rmdir) 38701da177e4SLinus Torvalds return -EPERM; 38711da177e4SLinus Torvalds 38721d2ef590SAl Viro dget(dentry); 38735955102cSAl Viro inode_lock(dentry->d_inode); 3874912dbc15SSage Weil 38751da177e4SLinus Torvalds error = -EBUSY; 38767af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3877912dbc15SSage Weil goto out; 3878912dbc15SSage Weil 38791da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3880912dbc15SSage Weil if (error) 3881912dbc15SSage Weil goto out; 3882912dbc15SSage Weil 38833cebde24SSage Weil shrink_dcache_parent(dentry); 38841da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3885912dbc15SSage Weil if (error) 3886912dbc15SSage Weil goto out; 3887912dbc15SSage Weil 38881da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3889d83c49f3SAl Viro dont_mount(dentry); 38908ed936b5SEric W. Biederman detach_mounts(dentry); 38911da177e4SLinus Torvalds 3892912dbc15SSage Weil out: 38935955102cSAl Viro inode_unlock(dentry->d_inode); 38941d2ef590SAl Viro dput(dentry); 3895912dbc15SSage Weil if (!error) 3896912dbc15SSage Weil d_delete(dentry); 38971da177e4SLinus Torvalds return error; 38981da177e4SLinus Torvalds } 38994d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 39001da177e4SLinus Torvalds 39015590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 39021da177e4SLinus Torvalds { 39031da177e4SLinus Torvalds int error = 0; 390491a27b2aSJeff Layton struct filename *name; 39051da177e4SLinus Torvalds struct dentry *dentry; 3906f5beed75SAl Viro struct path path; 3907f5beed75SAl Viro struct qstr last; 3908f5beed75SAl Viro int type; 3909c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3910c6ee9206SJeff Layton retry: 3911f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3912f5beed75SAl Viro &path, &last, &type, lookup_flags); 391391a27b2aSJeff Layton if (IS_ERR(name)) 391491a27b2aSJeff Layton return PTR_ERR(name); 39151da177e4SLinus Torvalds 3916f5beed75SAl Viro switch (type) { 39171da177e4SLinus Torvalds case LAST_DOTDOT: 39181da177e4SLinus Torvalds error = -ENOTEMPTY; 39191da177e4SLinus Torvalds goto exit1; 39201da177e4SLinus Torvalds case LAST_DOT: 39211da177e4SLinus Torvalds error = -EINVAL; 39221da177e4SLinus Torvalds goto exit1; 39231da177e4SLinus Torvalds case LAST_ROOT: 39241da177e4SLinus Torvalds error = -EBUSY; 39251da177e4SLinus Torvalds goto exit1; 39261da177e4SLinus Torvalds } 39270612d9fbSOGAWA Hirofumi 3928f5beed75SAl Viro error = mnt_want_write(path.mnt); 3929c30dabfeSJan Kara if (error) 3930c30dabfeSJan Kara goto exit1; 39310612d9fbSOGAWA Hirofumi 39325955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3933f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 39341da177e4SLinus Torvalds error = PTR_ERR(dentry); 39356902d925SDave Hansen if (IS_ERR(dentry)) 39366902d925SDave Hansen goto exit2; 3937e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3938e6bc45d6STheodore Ts'o error = -ENOENT; 3939e6bc45d6STheodore Ts'o goto exit3; 3940e6bc45d6STheodore Ts'o } 3941f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3942be6d3e56SKentaro Takeda if (error) 3943c30dabfeSJan Kara goto exit3; 3944f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 39450622753bSDave Hansen exit3: 39461da177e4SLinus Torvalds dput(dentry); 39476902d925SDave Hansen exit2: 39485955102cSAl Viro inode_unlock(path.dentry->d_inode); 3949f5beed75SAl Viro mnt_drop_write(path.mnt); 39501da177e4SLinus Torvalds exit1: 3951f5beed75SAl Viro path_put(&path); 39521da177e4SLinus Torvalds putname(name); 3953c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3954c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3955c6ee9206SJeff Layton goto retry; 3956c6ee9206SJeff Layton } 39571da177e4SLinus Torvalds return error; 39581da177e4SLinus Torvalds } 39591da177e4SLinus Torvalds 39603cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 39615590ff0dSUlrich Drepper { 39625590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 39635590ff0dSUlrich Drepper } 39645590ff0dSUlrich Drepper 3965b21996e3SJ. Bruce Fields /** 3966b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3967b21996e3SJ. Bruce Fields * @dir: parent directory 3968b21996e3SJ. Bruce Fields * @dentry: victim 3969b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3970b21996e3SJ. Bruce Fields * 3971b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3972b21996e3SJ. Bruce Fields * 3973b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3974b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3975b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3976b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3977b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3978b21996e3SJ. Bruce Fields * 3979b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3980b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3981b21996e3SJ. Bruce Fields * to be NFS exported. 3982b21996e3SJ. Bruce Fields */ 3983b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 39841da177e4SLinus Torvalds { 39859accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 39861da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 39871da177e4SLinus Torvalds 39881da177e4SLinus Torvalds if (error) 39891da177e4SLinus Torvalds return error; 39901da177e4SLinus Torvalds 3991acfa4380SAl Viro if (!dir->i_op->unlink) 39921da177e4SLinus Torvalds return -EPERM; 39931da177e4SLinus Torvalds 39945955102cSAl Viro inode_lock(target); 39958ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 39961da177e4SLinus Torvalds error = -EBUSY; 39971da177e4SLinus Torvalds else { 39981da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3999bec1052eSAl Viro if (!error) { 40005a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 40015a14696cSJ. Bruce Fields if (error) 4002b21996e3SJ. Bruce Fields goto out; 40031da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 40048ed936b5SEric W. Biederman if (!error) { 4005d83c49f3SAl Viro dont_mount(dentry); 40068ed936b5SEric W. Biederman detach_mounts(dentry); 40078ed936b5SEric W. Biederman } 4008bec1052eSAl Viro } 40091da177e4SLinus Torvalds } 4010b21996e3SJ. Bruce Fields out: 40115955102cSAl Viro inode_unlock(target); 40121da177e4SLinus Torvalds 40131da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 40141da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 40159accbb97SJ. Bruce Fields fsnotify_link_count(target); 40161da177e4SLinus Torvalds d_delete(dentry); 40171da177e4SLinus Torvalds } 40180eeca283SRobert Love 40191da177e4SLinus Torvalds return error; 40201da177e4SLinus Torvalds } 40214d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 40221da177e4SLinus Torvalds 40231da177e4SLinus Torvalds /* 40241da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 40251b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 40261da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 40271da177e4SLinus Torvalds * while waiting on the I/O. 40281da177e4SLinus Torvalds */ 40295590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 40301da177e4SLinus Torvalds { 40312ad94ae6SAl Viro int error; 403291a27b2aSJeff Layton struct filename *name; 40331da177e4SLinus Torvalds struct dentry *dentry; 4034f5beed75SAl Viro struct path path; 4035f5beed75SAl Viro struct qstr last; 4036f5beed75SAl Viro int type; 40371da177e4SLinus Torvalds struct inode *inode = NULL; 4038b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 40395d18f813SJeff Layton unsigned int lookup_flags = 0; 40405d18f813SJeff Layton retry: 4041f5beed75SAl Viro name = user_path_parent(dfd, pathname, 4042f5beed75SAl Viro &path, &last, &type, lookup_flags); 404391a27b2aSJeff Layton if (IS_ERR(name)) 404491a27b2aSJeff Layton return PTR_ERR(name); 40452ad94ae6SAl Viro 40461da177e4SLinus Torvalds error = -EISDIR; 4047f5beed75SAl Viro if (type != LAST_NORM) 40481da177e4SLinus Torvalds goto exit1; 40490612d9fbSOGAWA Hirofumi 4050f5beed75SAl Viro error = mnt_want_write(path.mnt); 4051c30dabfeSJan Kara if (error) 4052c30dabfeSJan Kara goto exit1; 4053b21996e3SJ. Bruce Fields retry_deleg: 40545955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 4055f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 40561da177e4SLinus Torvalds error = PTR_ERR(dentry); 40571da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 40581da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 4059f5beed75SAl Viro if (last.name[last.len]) 406050338b88STörök Edwin goto slashes; 40611da177e4SLinus Torvalds inode = dentry->d_inode; 4062b18825a7SDavid Howells if (d_is_negative(dentry)) 4063e6bc45d6STheodore Ts'o goto slashes; 40647de9c6eeSAl Viro ihold(inode); 4065f5beed75SAl Viro error = security_path_unlink(&path, dentry); 4066be6d3e56SKentaro Takeda if (error) 4067c30dabfeSJan Kara goto exit2; 4068f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 40691da177e4SLinus Torvalds exit2: 40701da177e4SLinus Torvalds dput(dentry); 40711da177e4SLinus Torvalds } 40725955102cSAl Viro inode_unlock(path.dentry->d_inode); 40731da177e4SLinus Torvalds if (inode) 40741da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 4075b21996e3SJ. Bruce Fields inode = NULL; 4076b21996e3SJ. Bruce Fields if (delegated_inode) { 40775a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4078b21996e3SJ. Bruce Fields if (!error) 4079b21996e3SJ. Bruce Fields goto retry_deleg; 4080b21996e3SJ. Bruce Fields } 4081f5beed75SAl Viro mnt_drop_write(path.mnt); 40821da177e4SLinus Torvalds exit1: 4083f5beed75SAl Viro path_put(&path); 40841da177e4SLinus Torvalds putname(name); 40855d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 40865d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 40875d18f813SJeff Layton inode = NULL; 40885d18f813SJeff Layton goto retry; 40895d18f813SJeff Layton } 40901da177e4SLinus Torvalds return error; 40911da177e4SLinus Torvalds 40921da177e4SLinus Torvalds slashes: 4093b18825a7SDavid Howells if (d_is_negative(dentry)) 4094b18825a7SDavid Howells error = -ENOENT; 409544b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 4096b18825a7SDavid Howells error = -EISDIR; 4097b18825a7SDavid Howells else 4098b18825a7SDavid Howells error = -ENOTDIR; 40991da177e4SLinus Torvalds goto exit2; 41001da177e4SLinus Torvalds } 41011da177e4SLinus Torvalds 41022e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 41035590ff0dSUlrich Drepper { 41045590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 41055590ff0dSUlrich Drepper return -EINVAL; 41065590ff0dSUlrich Drepper 41075590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 41085590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 41095590ff0dSUlrich Drepper 41105590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 41115590ff0dSUlrich Drepper } 41125590ff0dSUlrich Drepper 41133480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 41145590ff0dSUlrich Drepper { 41155590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 41165590ff0dSUlrich Drepper } 41175590ff0dSUlrich Drepper 4118db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 41191da177e4SLinus Torvalds { 4120a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 41211da177e4SLinus Torvalds 41221da177e4SLinus Torvalds if (error) 41231da177e4SLinus Torvalds return error; 41241da177e4SLinus Torvalds 4125acfa4380SAl Viro if (!dir->i_op->symlink) 41261da177e4SLinus Torvalds return -EPERM; 41271da177e4SLinus Torvalds 41281da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 41291da177e4SLinus Torvalds if (error) 41301da177e4SLinus Torvalds return error; 41311da177e4SLinus Torvalds 41321da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 4133a74574aaSStephen Smalley if (!error) 4134f38aa942SAmy Griffis fsnotify_create(dir, dentry); 41351da177e4SLinus Torvalds return error; 41361da177e4SLinus Torvalds } 41374d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 41381da177e4SLinus Torvalds 41392e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 41402e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 41411da177e4SLinus Torvalds { 41422ad94ae6SAl Viro int error; 414391a27b2aSJeff Layton struct filename *from; 41446902d925SDave Hansen struct dentry *dentry; 4145dae6ad8fSAl Viro struct path path; 4146f46d3567SJeff Layton unsigned int lookup_flags = 0; 41471da177e4SLinus Torvalds 41481da177e4SLinus Torvalds from = getname(oldname); 41491da177e4SLinus Torvalds if (IS_ERR(from)) 41501da177e4SLinus Torvalds return PTR_ERR(from); 4151f46d3567SJeff Layton retry: 4152f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 41531da177e4SLinus Torvalds error = PTR_ERR(dentry); 41546902d925SDave Hansen if (IS_ERR(dentry)) 4155dae6ad8fSAl Viro goto out_putname; 41566902d925SDave Hansen 415791a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4158a8104a9fSAl Viro if (!error) 415991a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4160921a1650SAl Viro done_path_create(&path, dentry); 4161f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4162f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4163f46d3567SJeff Layton goto retry; 4164f46d3567SJeff Layton } 41656902d925SDave Hansen out_putname: 41661da177e4SLinus Torvalds putname(from); 41671da177e4SLinus Torvalds return error; 41681da177e4SLinus Torvalds } 41691da177e4SLinus Torvalds 41703480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 41715590ff0dSUlrich Drepper { 41725590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 41735590ff0dSUlrich Drepper } 41745590ff0dSUlrich Drepper 4175146a8595SJ. Bruce Fields /** 4176146a8595SJ. Bruce Fields * vfs_link - create a new link 4177146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4178146a8595SJ. Bruce Fields * @dir: new parent 4179146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4180146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4181146a8595SJ. Bruce Fields * 4182146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4183146a8595SJ. Bruce Fields * 4184146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4185146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4186146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4187146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4188146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4189146a8595SJ. Bruce Fields * 4190146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4191146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4192146a8595SJ. Bruce Fields * to be NFS exported. 4193146a8595SJ. Bruce Fields */ 4194146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 41951da177e4SLinus Torvalds { 41961da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 41978de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 41981da177e4SLinus Torvalds int error; 41991da177e4SLinus Torvalds 42001da177e4SLinus Torvalds if (!inode) 42011da177e4SLinus Torvalds return -ENOENT; 42021da177e4SLinus Torvalds 4203a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 42041da177e4SLinus Torvalds if (error) 42051da177e4SLinus Torvalds return error; 42061da177e4SLinus Torvalds 42071da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 42081da177e4SLinus Torvalds return -EXDEV; 42091da177e4SLinus Torvalds 42101da177e4SLinus Torvalds /* 42111da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 42121da177e4SLinus Torvalds */ 42131da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 42141da177e4SLinus Torvalds return -EPERM; 42150bd23d09SEric W. Biederman /* 42160bd23d09SEric W. Biederman * Updating the link count will likely cause i_uid and i_gid to 42170bd23d09SEric W. Biederman * be writen back improperly if their true value is unknown to 42180bd23d09SEric W. Biederman * the vfs. 42190bd23d09SEric W. Biederman */ 42200bd23d09SEric W. Biederman if (HAS_UNMAPPED_ID(inode)) 42210bd23d09SEric W. Biederman return -EPERM; 4222acfa4380SAl Viro if (!dir->i_op->link) 42231da177e4SLinus Torvalds return -EPERM; 42247e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 42251da177e4SLinus Torvalds return -EPERM; 42261da177e4SLinus Torvalds 42271da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 42281da177e4SLinus Torvalds if (error) 42291da177e4SLinus Torvalds return error; 42301da177e4SLinus Torvalds 42315955102cSAl Viro inode_lock(inode); 4232aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4233f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4234aae8a97dSAneesh Kumar K.V error = -ENOENT; 42358de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 42368de52778SAl Viro error = -EMLINK; 4237146a8595SJ. Bruce Fields else { 4238146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4239146a8595SJ. Bruce Fields if (!error) 42401da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4241146a8595SJ. Bruce Fields } 4242f4e0c30cSAl Viro 4243f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4244f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4245f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4246f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4247f4e0c30cSAl Viro } 42485955102cSAl Viro inode_unlock(inode); 4249e31e14ecSStephen Smalley if (!error) 42507e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 42511da177e4SLinus Torvalds return error; 42521da177e4SLinus Torvalds } 42534d359507SAl Viro EXPORT_SYMBOL(vfs_link); 42541da177e4SLinus Torvalds 42551da177e4SLinus Torvalds /* 42561da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 42571da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 42581da177e4SLinus Torvalds * newname. --KAB 42591da177e4SLinus Torvalds * 42601da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 42611da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 42621da177e4SLinus Torvalds * and other special files. --ADM 42631da177e4SLinus Torvalds */ 42642e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 42652e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 42661da177e4SLinus Torvalds { 42671da177e4SLinus Torvalds struct dentry *new_dentry; 4268dae6ad8fSAl Viro struct path old_path, new_path; 4269146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 427011a7b371SAneesh Kumar K.V int how = 0; 42711da177e4SLinus Torvalds int error; 42721da177e4SLinus Torvalds 427311a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4274c04030e1SUlrich Drepper return -EINVAL; 427511a7b371SAneesh Kumar K.V /* 4276f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4277f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4278f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 427911a7b371SAneesh Kumar K.V */ 4280f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4281f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4282f0cc6ffbSLinus Torvalds return -ENOENT; 428311a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4284f0cc6ffbSLinus Torvalds } 4285c04030e1SUlrich Drepper 428611a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 428711a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4288442e31caSJeff Layton retry: 428911a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 42901da177e4SLinus Torvalds if (error) 42912ad94ae6SAl Viro return error; 42922ad94ae6SAl Viro 4293442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4294442e31caSJeff Layton (how & LOOKUP_REVAL)); 42951da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 42966902d925SDave Hansen if (IS_ERR(new_dentry)) 4297dae6ad8fSAl Viro goto out; 4298dae6ad8fSAl Viro 4299dae6ad8fSAl Viro error = -EXDEV; 4300dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4301dae6ad8fSAl Viro goto out_dput; 4302800179c9SKees Cook error = may_linkat(&old_path); 4303800179c9SKees Cook if (unlikely(error)) 4304800179c9SKees Cook goto out_dput; 4305dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4306be6d3e56SKentaro Takeda if (error) 4307a8104a9fSAl Viro goto out_dput; 4308146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 430975c3f29dSDave Hansen out_dput: 4310921a1650SAl Viro done_path_create(&new_path, new_dentry); 4311146a8595SJ. Bruce Fields if (delegated_inode) { 4312146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4313d22e6338SOleg Drokin if (!error) { 4314d22e6338SOleg Drokin path_put(&old_path); 4315146a8595SJ. Bruce Fields goto retry; 4316146a8595SJ. Bruce Fields } 4317d22e6338SOleg Drokin } 4318442e31caSJeff Layton if (retry_estale(error, how)) { 4319d22e6338SOleg Drokin path_put(&old_path); 4320442e31caSJeff Layton how |= LOOKUP_REVAL; 4321442e31caSJeff Layton goto retry; 4322442e31caSJeff Layton } 43231da177e4SLinus Torvalds out: 43242d8f3038SAl Viro path_put(&old_path); 43251da177e4SLinus Torvalds 43261da177e4SLinus Torvalds return error; 43271da177e4SLinus Torvalds } 43281da177e4SLinus Torvalds 43293480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 43305590ff0dSUlrich Drepper { 4331c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 43325590ff0dSUlrich Drepper } 43335590ff0dSUlrich Drepper 4334bc27027aSMiklos Szeredi /** 4335bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4336bc27027aSMiklos Szeredi * @old_dir: parent of source 4337bc27027aSMiklos Szeredi * @old_dentry: source 4338bc27027aSMiklos Szeredi * @new_dir: parent of destination 4339bc27027aSMiklos Szeredi * @new_dentry: destination 4340bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4341520c8b16SMiklos Szeredi * @flags: rename flags 4342bc27027aSMiklos Szeredi * 4343bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4344bc27027aSMiklos Szeredi * 4345bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4346bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4347bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4348bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4349bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4350bc27027aSMiklos Szeredi * so. 4351bc27027aSMiklos Szeredi * 4352bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4353bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4354bc27027aSMiklos Szeredi * to be NFS exported. 4355bc27027aSMiklos Szeredi * 43561da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 43571da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 43581da177e4SLinus Torvalds * Problems: 4359d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 43601da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 43611da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4362a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 43631da177e4SLinus Torvalds * story. 43646cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 43656cedba89SJ. Bruce Fields * and source (if it is not a directory). 43661b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 43671da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 43681da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4369a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 43701da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 43711da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 43721da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4373a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 43741da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 43751da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 43761da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4377e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 43781b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 43791da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4380c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 43811da177e4SLinus Torvalds * locking]. 43821da177e4SLinus Torvalds */ 43831da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 43848e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4385520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 43861da177e4SLinus Torvalds { 43871da177e4SLinus Torvalds int error; 4388bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 438959b0df21SEric Paris const unsigned char *old_name; 4390bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4391bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4392da1ce067SMiklos Szeredi bool new_is_dir = false; 4393da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 43941da177e4SLinus Torvalds 43959409e22aSMiklos Szeredi /* 43969409e22aSMiklos Szeredi * Check source == target. 43979409e22aSMiklos Szeredi * On overlayfs need to look at underlying inodes. 43989409e22aSMiklos Szeredi */ 43999409e22aSMiklos Szeredi if (vfs_select_inode(old_dentry, 0) == vfs_select_inode(new_dentry, 0)) 44001da177e4SLinus Torvalds return 0; 44011da177e4SLinus Torvalds 44021da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 44031da177e4SLinus Torvalds if (error) 44041da177e4SLinus Torvalds return error; 44051da177e4SLinus Torvalds 4406da1ce067SMiklos Szeredi if (!target) { 4407a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4408da1ce067SMiklos Szeredi } else { 4409da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4410da1ce067SMiklos Szeredi 4411da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 44121da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4413da1ce067SMiklos Szeredi else 4414da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4415da1ce067SMiklos Szeredi } 44161da177e4SLinus Torvalds if (error) 44171da177e4SLinus Torvalds return error; 44181da177e4SLinus Torvalds 44197177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 44201da177e4SLinus Torvalds return -EPERM; 44211da177e4SLinus Torvalds 4422520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4423520c8b16SMiklos Szeredi return -EINVAL; 4424520c8b16SMiklos Szeredi 4425bc27027aSMiklos Szeredi /* 4426bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4427bc27027aSMiklos Szeredi * we'll need to flip '..'. 4428bc27027aSMiklos Szeredi */ 4429da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4430da1ce067SMiklos Szeredi if (is_dir) { 4431bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4432bc27027aSMiklos Szeredi if (error) 4433bc27027aSMiklos Szeredi return error; 4434bc27027aSMiklos Szeredi } 4435da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4436da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4437da1ce067SMiklos Szeredi if (error) 4438da1ce067SMiklos Szeredi return error; 4439da1ce067SMiklos Szeredi } 4440da1ce067SMiklos Szeredi } 44410eeca283SRobert Love 44420b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 44430b3974ebSMiklos Szeredi flags); 4444bc27027aSMiklos Szeredi if (error) 4445bc27027aSMiklos Szeredi return error; 4446bc27027aSMiklos Szeredi 4447bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4448bc27027aSMiklos Szeredi dget(new_dentry); 4449da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4450bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4451bc27027aSMiklos Szeredi else if (target) 44525955102cSAl Viro inode_lock(target); 4453bc27027aSMiklos Szeredi 4454bc27027aSMiklos Szeredi error = -EBUSY; 44557af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4456bc27027aSMiklos Szeredi goto out; 4457bc27027aSMiklos Szeredi 4458da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4459bc27027aSMiklos Szeredi error = -EMLINK; 4460da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4461bc27027aSMiklos Szeredi goto out; 4462da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4463da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4464da1ce067SMiklos Szeredi goto out; 4465da1ce067SMiklos Szeredi } 4466da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4467bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4468da1ce067SMiklos Szeredi if (!is_dir) { 4469bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4470bc27027aSMiklos Szeredi if (error) 4471bc27027aSMiklos Szeredi goto out; 4472da1ce067SMiklos Szeredi } 4473da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4474bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4475bc27027aSMiklos Szeredi if (error) 4476bc27027aSMiklos Szeredi goto out; 4477bc27027aSMiklos Szeredi } 44787177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4479520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4480520c8b16SMiklos Szeredi new_dir, new_dentry); 4481520c8b16SMiklos Szeredi } else { 44827177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4483520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4484520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4485520c8b16SMiklos Szeredi } 4486bc27027aSMiklos Szeredi if (error) 4487bc27027aSMiklos Szeredi goto out; 4488bc27027aSMiklos Szeredi 4489da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 44901da177e4SLinus Torvalds if (is_dir) 4491bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4492bc27027aSMiklos Szeredi dont_mount(new_dentry); 44938ed936b5SEric W. Biederman detach_mounts(new_dentry); 4494bc27027aSMiklos Szeredi } 4495da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4496da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4497bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4498da1ce067SMiklos Szeredi else 4499da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4500da1ce067SMiklos Szeredi } 4501bc27027aSMiklos Szeredi out: 4502da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4503bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4504bc27027aSMiklos Szeredi else if (target) 45055955102cSAl Viro inode_unlock(target); 4506bc27027aSMiklos Szeredi dput(new_dentry); 4507da1ce067SMiklos Szeredi if (!error) { 4508123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4509da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4510da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4511da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4512da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4513da1ce067SMiklos Szeredi } 4514da1ce067SMiklos Szeredi } 45150eeca283SRobert Love fsnotify_oldname_free(old_name); 45160eeca283SRobert Love 45171da177e4SLinus Torvalds return error; 45181da177e4SLinus Torvalds } 45194d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 45201da177e4SLinus Torvalds 4521520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4522520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 45231da177e4SLinus Torvalds { 45241da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 45251da177e4SLinus Torvalds struct dentry *trap; 4526f5beed75SAl Viro struct path old_path, new_path; 4527f5beed75SAl Viro struct qstr old_last, new_last; 4528f5beed75SAl Viro int old_type, new_type; 45298e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 453091a27b2aSJeff Layton struct filename *from; 453191a27b2aSJeff Layton struct filename *to; 4532f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4533c6a94284SJeff Layton bool should_retry = false; 45342ad94ae6SAl Viro int error; 4535520c8b16SMiklos Szeredi 45360d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4537da1ce067SMiklos Szeredi return -EINVAL; 4538da1ce067SMiklos Szeredi 45390d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 45400d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4541520c8b16SMiklos Szeredi return -EINVAL; 4542520c8b16SMiklos Szeredi 45430d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 45440d7a8555SMiklos Szeredi return -EPERM; 45450d7a8555SMiklos Szeredi 4546f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4547f5beed75SAl Viro target_flags = 0; 4548f5beed75SAl Viro 4549c6a94284SJeff Layton retry: 4550f5beed75SAl Viro from = user_path_parent(olddfd, oldname, 4551f5beed75SAl Viro &old_path, &old_last, &old_type, lookup_flags); 455291a27b2aSJeff Layton if (IS_ERR(from)) { 455391a27b2aSJeff Layton error = PTR_ERR(from); 45541da177e4SLinus Torvalds goto exit; 455591a27b2aSJeff Layton } 45561da177e4SLinus Torvalds 4557f5beed75SAl Viro to = user_path_parent(newdfd, newname, 4558f5beed75SAl Viro &new_path, &new_last, &new_type, lookup_flags); 455991a27b2aSJeff Layton if (IS_ERR(to)) { 456091a27b2aSJeff Layton error = PTR_ERR(to); 45611da177e4SLinus Torvalds goto exit1; 456291a27b2aSJeff Layton } 45631da177e4SLinus Torvalds 45641da177e4SLinus Torvalds error = -EXDEV; 4565f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 45661da177e4SLinus Torvalds goto exit2; 45671da177e4SLinus Torvalds 45681da177e4SLinus Torvalds error = -EBUSY; 4569f5beed75SAl Viro if (old_type != LAST_NORM) 45701da177e4SLinus Torvalds goto exit2; 45711da177e4SLinus Torvalds 45720a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 45730a7c3937SMiklos Szeredi error = -EEXIST; 4574f5beed75SAl Viro if (new_type != LAST_NORM) 45751da177e4SLinus Torvalds goto exit2; 45761da177e4SLinus Torvalds 4577f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4578c30dabfeSJan Kara if (error) 4579c30dabfeSJan Kara goto exit2; 4580c30dabfeSJan Kara 45818e6d782cSJ. Bruce Fields retry_deleg: 4582f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 45831da177e4SLinus Torvalds 4584f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 45851da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 45861da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 45871da177e4SLinus Torvalds goto exit3; 45881da177e4SLinus Torvalds /* source must exist */ 45891da177e4SLinus Torvalds error = -ENOENT; 4590b18825a7SDavid Howells if (d_is_negative(old_dentry)) 45911da177e4SLinus Torvalds goto exit4; 4592f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 45931da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 45941da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 45951da177e4SLinus Torvalds goto exit4; 45960a7c3937SMiklos Szeredi error = -EEXIST; 45970a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 45980a7c3937SMiklos Szeredi goto exit5; 4599da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4600da1ce067SMiklos Szeredi error = -ENOENT; 4601da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4602da1ce067SMiklos Szeredi goto exit5; 4603da1ce067SMiklos Szeredi 4604da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4605da1ce067SMiklos Szeredi error = -ENOTDIR; 4606f5beed75SAl Viro if (new_last.name[new_last.len]) 4607da1ce067SMiklos Szeredi goto exit5; 4608da1ce067SMiklos Szeredi } 4609da1ce067SMiklos Szeredi } 46100a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 46110a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 46120a7c3937SMiklos Szeredi error = -ENOTDIR; 4613f5beed75SAl Viro if (old_last.name[old_last.len]) 46140a7c3937SMiklos Szeredi goto exit5; 4615f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 46160a7c3937SMiklos Szeredi goto exit5; 46170a7c3937SMiklos Szeredi } 46180a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 46190a7c3937SMiklos Szeredi error = -EINVAL; 46200a7c3937SMiklos Szeredi if (old_dentry == trap) 46210a7c3937SMiklos Szeredi goto exit5; 46221da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4623da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 46241da177e4SLinus Torvalds error = -ENOTEMPTY; 46251da177e4SLinus Torvalds if (new_dentry == trap) 46261da177e4SLinus Torvalds goto exit5; 46271da177e4SLinus Torvalds 4628f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4629f5beed75SAl Viro &new_path, new_dentry, flags); 4630be6d3e56SKentaro Takeda if (error) 4631c30dabfeSJan Kara goto exit5; 4632f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4633f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4634520c8b16SMiklos Szeredi &delegated_inode, flags); 46351da177e4SLinus Torvalds exit5: 46361da177e4SLinus Torvalds dput(new_dentry); 46371da177e4SLinus Torvalds exit4: 46381da177e4SLinus Torvalds dput(old_dentry); 46391da177e4SLinus Torvalds exit3: 4640f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 46418e6d782cSJ. Bruce Fields if (delegated_inode) { 46428e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 46438e6d782cSJ. Bruce Fields if (!error) 46448e6d782cSJ. Bruce Fields goto retry_deleg; 46458e6d782cSJ. Bruce Fields } 4646f5beed75SAl Viro mnt_drop_write(old_path.mnt); 46471da177e4SLinus Torvalds exit2: 4648c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4649c6a94284SJeff Layton should_retry = true; 4650f5beed75SAl Viro path_put(&new_path); 46512ad94ae6SAl Viro putname(to); 46521da177e4SLinus Torvalds exit1: 4653f5beed75SAl Viro path_put(&old_path); 46541da177e4SLinus Torvalds putname(from); 4655c6a94284SJeff Layton if (should_retry) { 4656c6a94284SJeff Layton should_retry = false; 4657c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4658c6a94284SJeff Layton goto retry; 4659c6a94284SJeff Layton } 46602ad94ae6SAl Viro exit: 46611da177e4SLinus Torvalds return error; 46621da177e4SLinus Torvalds } 46631da177e4SLinus Torvalds 4664520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4665520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4666520c8b16SMiklos Szeredi { 4667520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4668520c8b16SMiklos Szeredi } 4669520c8b16SMiklos Szeredi 4670a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 46715590ff0dSUlrich Drepper { 4672520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 46735590ff0dSUlrich Drepper } 46745590ff0dSUlrich Drepper 4675787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4676787fb6bcSMiklos Szeredi { 4677787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4678787fb6bcSMiklos Szeredi if (error) 4679787fb6bcSMiklos Szeredi return error; 4680787fb6bcSMiklos Szeredi 4681787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4682787fb6bcSMiklos Szeredi return -EPERM; 4683787fb6bcSMiklos Szeredi 4684787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4685787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4686787fb6bcSMiklos Szeredi } 4687787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4688787fb6bcSMiklos Szeredi 46895d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 46901da177e4SLinus Torvalds { 46915d826c84SAl Viro int len = PTR_ERR(link); 46921da177e4SLinus Torvalds if (IS_ERR(link)) 46931da177e4SLinus Torvalds goto out; 46941da177e4SLinus Torvalds 46951da177e4SLinus Torvalds len = strlen(link); 46961da177e4SLinus Torvalds if (len > (unsigned) buflen) 46971da177e4SLinus Torvalds len = buflen; 46981da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 46991da177e4SLinus Torvalds len = -EFAULT; 47001da177e4SLinus Torvalds out: 47011da177e4SLinus Torvalds return len; 47021da177e4SLinus Torvalds } 47031da177e4SLinus Torvalds 47041da177e4SLinus Torvalds /* 47051da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 47066b255391SAl Viro * have ->get_link() not calling nd_jump_link(). Using (or not using) it 47076b255391SAl Viro * for any given inode is up to filesystem. 47081da177e4SLinus Torvalds */ 47091da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 47101da177e4SLinus Torvalds { 4711fceef393SAl Viro DEFINE_DELAYED_CALL(done); 47125f2c4179SAl Viro struct inode *inode = d_inode(dentry); 47135f2c4179SAl Viro const char *link = inode->i_link; 4714694a1764SMarcin Slusarz int res; 4715cc314eefSLinus Torvalds 4716d4dee48bSAl Viro if (!link) { 4717fceef393SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4718680baacbSAl Viro if (IS_ERR(link)) 4719680baacbSAl Viro return PTR_ERR(link); 4720d4dee48bSAl Viro } 4721680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 4722fceef393SAl Viro do_delayed_call(&done); 4723694a1764SMarcin Slusarz return res; 47241da177e4SLinus Torvalds } 47254d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 47261da177e4SLinus Torvalds 47271da177e4SLinus Torvalds /* get the link contents into pagecache */ 47286b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4729fceef393SAl Viro struct delayed_call *callback) 47301da177e4SLinus Torvalds { 4731ebd09abbSDuane Griffin char *kaddr; 47321da177e4SLinus Torvalds struct page *page; 47336b255391SAl Viro struct address_space *mapping = inode->i_mapping; 47346b255391SAl Viro 4735d3883d4fSAl Viro if (!dentry) { 4736d3883d4fSAl Viro page = find_get_page(mapping, 0); 4737d3883d4fSAl Viro if (!page) 47386b255391SAl Viro return ERR_PTR(-ECHILD); 4739d3883d4fSAl Viro if (!PageUptodate(page)) { 4740d3883d4fSAl Viro put_page(page); 4741d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4742d3883d4fSAl Viro } 4743d3883d4fSAl Viro } else { 4744090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 47451da177e4SLinus Torvalds if (IS_ERR(page)) 47466fe6900eSNick Piggin return (char*)page; 4747d3883d4fSAl Viro } 4748fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 474921fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 475021fc61c7SAl Viro kaddr = page_address(page); 47516b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4752ebd09abbSDuane Griffin return kaddr; 47531da177e4SLinus Torvalds } 47541da177e4SLinus Torvalds 47556b255391SAl Viro EXPORT_SYMBOL(page_get_link); 47561da177e4SLinus Torvalds 4757fceef393SAl Viro void page_put_link(void *arg) 47581da177e4SLinus Torvalds { 4759fceef393SAl Viro put_page(arg); 47601da177e4SLinus Torvalds } 47614d359507SAl Viro EXPORT_SYMBOL(page_put_link); 47621da177e4SLinus Torvalds 4763aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4764aa80deabSAl Viro { 4765fceef393SAl Viro DEFINE_DELAYED_CALL(done); 47666b255391SAl Viro int res = readlink_copy(buffer, buflen, 47676b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4768fceef393SAl Viro &done)); 4769fceef393SAl Viro do_delayed_call(&done); 4770aa80deabSAl Viro return res; 4771aa80deabSAl Viro } 4772aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4773aa80deabSAl Viro 477454566b2cSNick Piggin /* 477554566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 477654566b2cSNick Piggin */ 477754566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 47781da177e4SLinus Torvalds { 47791da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 47800adb25d2SKirill Korotaev struct page *page; 4781afddba49SNick Piggin void *fsdata; 4782beb497abSDmitriy Monakhov int err; 478354566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 478454566b2cSNick Piggin if (nofs) 478554566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 47861da177e4SLinus Torvalds 47877e53cac4SNeilBrown retry: 4788afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 478954566b2cSNick Piggin flags, &page, &fsdata); 47901da177e4SLinus Torvalds if (err) 4791afddba49SNick Piggin goto fail; 4792afddba49SNick Piggin 479321fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4794afddba49SNick Piggin 4795afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4796afddba49SNick Piggin page, fsdata); 47971da177e4SLinus Torvalds if (err < 0) 47981da177e4SLinus Torvalds goto fail; 4799afddba49SNick Piggin if (err < len-1) 4800afddba49SNick Piggin goto retry; 4801afddba49SNick Piggin 48021da177e4SLinus Torvalds mark_inode_dirty(inode); 48031da177e4SLinus Torvalds return 0; 48041da177e4SLinus Torvalds fail: 48051da177e4SLinus Torvalds return err; 48061da177e4SLinus Torvalds } 48074d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 48081da177e4SLinus Torvalds 48090adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 48100adb25d2SKirill Korotaev { 48110adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4812c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 48130adb25d2SKirill Korotaev } 48144d359507SAl Viro EXPORT_SYMBOL(page_symlink); 48150adb25d2SKirill Korotaev 481692e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 48171da177e4SLinus Torvalds .readlink = generic_readlink, 48186b255391SAl Viro .get_link = page_get_link, 48191da177e4SLinus Torvalds }; 48201da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4821