11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namei.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Some corrections by tytso. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 121da177e4SLinus Torvalds * lookup logic. 131da177e4SLinus Torvalds */ 141da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 151da177e4SLinus Torvalds */ 161da177e4SLinus Torvalds 171da177e4SLinus Torvalds #include <linux/init.h> 18630d9c47SPaul Gortmaker #include <linux/export.h> 1944696908SDavid S. Miller #include <linux/kernel.h> 201da177e4SLinus Torvalds #include <linux/slab.h> 211da177e4SLinus Torvalds #include <linux/fs.h> 221da177e4SLinus Torvalds #include <linux/namei.h> 231da177e4SLinus Torvalds #include <linux/pagemap.h> 240eeca283SRobert Love #include <linux/fsnotify.h> 251da177e4SLinus Torvalds #include <linux/personality.h> 261da177e4SLinus Torvalds #include <linux/security.h> 276146f0d5SMimi Zohar #include <linux/ima.h> 281da177e4SLinus Torvalds #include <linux/syscalls.h> 291da177e4SLinus Torvalds #include <linux/mount.h> 301da177e4SLinus Torvalds #include <linux/audit.h> 3116f7e0feSRandy Dunlap #include <linux/capability.h> 32834f2a4aSTrond Myklebust #include <linux/file.h> 335590ff0dSUlrich Drepper #include <linux/fcntl.h> 3408ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 355ad4e53bSAl Viro #include <linux/fs_struct.h> 36e77819e5SLinus Torvalds #include <linux/posix_acl.h> 3799d263d4SLinus Torvalds #include <linux/hash.h> 382a18da7aSGeorge Spelvin #include <linux/bitops.h> 39aeaa4a79SEric W. Biederman #include <linux/init_task.h> 407c0f6ba6SLinus Torvalds #include <linux/uaccess.h> 411da177e4SLinus Torvalds 42e81e3f4dSEric Paris #include "internal.h" 43c7105365SAl Viro #include "mount.h" 44e81e3f4dSEric Paris 451da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 461da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 471da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 481da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 491da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 501da177e4SLinus Torvalds * 511da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 521da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 531da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 541da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 551da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 561da177e4SLinus Torvalds * the special cases of the former code. 571da177e4SLinus Torvalds * 581da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 591da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 601da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 611da177e4SLinus Torvalds * 621da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 631da177e4SLinus Torvalds * resolution to correspond with current state of the code. 641da177e4SLinus Torvalds * 651da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 661da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 671da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 681da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 691da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 701da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 711da177e4SLinus Torvalds */ 721da177e4SLinus Torvalds 731da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 741da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 751da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 761da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 771da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 781da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7925985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 801da177e4SLinus Torvalds * 811da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 821da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 831da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 841da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 851da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 861da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 871da177e4SLinus Torvalds * and in the old Linux semantics. 881da177e4SLinus Torvalds */ 891da177e4SLinus Torvalds 901da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 911da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 921da177e4SLinus Torvalds * 931da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 941da177e4SLinus Torvalds */ 951da177e4SLinus Torvalds 961da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 971da177e4SLinus Torvalds * inside the path - always follow. 981da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 991da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 1001da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 1011da177e4SLinus Torvalds * otherwise - don't follow. 1021da177e4SLinus Torvalds * (applied in that order). 1031da177e4SLinus Torvalds * 1041da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1051da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1061da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1071da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1081da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1091da177e4SLinus Torvalds */ 1101da177e4SLinus Torvalds /* 1111da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 112a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1131da177e4SLinus Torvalds * any extra contention... 1141da177e4SLinus Torvalds */ 1151da177e4SLinus Torvalds 1161da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1171da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1181da177e4SLinus Torvalds * kernel data space before using them.. 1191da177e4SLinus Torvalds * 1201da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1211da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1221da177e4SLinus Torvalds */ 1237950e385SJeff Layton 124fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12591a27b2aSJeff Layton 12651f39a1fSDavid Drysdale struct filename * 12791a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12891a27b2aSJeff Layton { 12994b5d262SAl Viro struct filename *result; 1307950e385SJeff Layton char *kname; 13194b5d262SAl Viro int len; 1321da177e4SLinus Torvalds 1337ac86265SJeff Layton result = audit_reusename(filename); 1347ac86265SJeff Layton if (result) 1357ac86265SJeff Layton return result; 1367ac86265SJeff Layton 1377950e385SJeff Layton result = __getname(); 1383f9f0aa6SLinus Torvalds if (unlikely(!result)) 1394043cde8SEric Paris return ERR_PTR(-ENOMEM); 1401da177e4SLinus Torvalds 1417950e385SJeff Layton /* 1427950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1437950e385SJeff Layton * allocation 1447950e385SJeff Layton */ 145fd2f7cb5SAl Viro kname = (char *)result->iname; 14691a27b2aSJeff Layton result->name = kname; 1477950e385SJeff Layton 14894b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 14991a27b2aSJeff Layton if (unlikely(len < 0)) { 15094b5d262SAl Viro __putname(result); 15194b5d262SAl Viro return ERR_PTR(len); 15291a27b2aSJeff Layton } 1533f9f0aa6SLinus Torvalds 1547950e385SJeff Layton /* 1557950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1567950e385SJeff Layton * separate struct filename so we can dedicate the entire 1577950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1587950e385SJeff Layton * userland. 1597950e385SJeff Layton */ 16094b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 161fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1627950e385SJeff Layton kname = (char *)result; 1637950e385SJeff Layton 164fd2f7cb5SAl Viro /* 165fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 166fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 167fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 168fd2f7cb5SAl Viro */ 169fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 17094b5d262SAl Viro if (unlikely(!result)) { 17194b5d262SAl Viro __putname(kname); 17294b5d262SAl Viro return ERR_PTR(-ENOMEM); 1737950e385SJeff Layton } 1747950e385SJeff Layton result->name = kname; 17594b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17694b5d262SAl Viro if (unlikely(len < 0)) { 17794b5d262SAl Viro __putname(kname); 17894b5d262SAl Viro kfree(result); 17994b5d262SAl Viro return ERR_PTR(len); 18094b5d262SAl Viro } 18194b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18294b5d262SAl Viro __putname(kname); 18394b5d262SAl Viro kfree(result); 18494b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18594b5d262SAl Viro } 1867950e385SJeff Layton } 1877950e385SJeff Layton 18894b5d262SAl Viro result->refcnt = 1; 1893f9f0aa6SLinus Torvalds /* The empty path is special. */ 1903f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1913f9f0aa6SLinus Torvalds if (empty) 1921fa1e7f6SAndy Whitcroft *empty = 1; 19394b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19494b5d262SAl Viro putname(result); 19594b5d262SAl Viro return ERR_PTR(-ENOENT); 1961da177e4SLinus Torvalds } 19794b5d262SAl Viro } 1987950e385SJeff Layton 1997950e385SJeff Layton result->uptr = filename; 200c4ad8f98SLinus Torvalds result->aname = NULL; 2011da177e4SLinus Torvalds audit_getname(result); 2021da177e4SLinus Torvalds return result; 2033f9f0aa6SLinus Torvalds } 2043f9f0aa6SLinus Torvalds 20591a27b2aSJeff Layton struct filename * 20691a27b2aSJeff Layton getname(const char __user * filename) 207f52e0c11SAl Viro { 208f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 209f52e0c11SAl Viro } 210f52e0c11SAl Viro 211c4ad8f98SLinus Torvalds struct filename * 212c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 213c4ad8f98SLinus Torvalds { 214c4ad8f98SLinus Torvalds struct filename *result; 21508518549SPaul Moore int len = strlen(filename) + 1; 216c4ad8f98SLinus Torvalds 217c4ad8f98SLinus Torvalds result = __getname(); 218c4ad8f98SLinus Torvalds if (unlikely(!result)) 219c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 220c4ad8f98SLinus Torvalds 22108518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 222fd2f7cb5SAl Viro result->name = (char *)result->iname; 22308518549SPaul Moore } else if (len <= PATH_MAX) { 22408518549SPaul Moore struct filename *tmp; 22508518549SPaul Moore 22608518549SPaul Moore tmp = kmalloc(sizeof(*tmp), GFP_KERNEL); 22708518549SPaul Moore if (unlikely(!tmp)) { 22808518549SPaul Moore __putname(result); 22908518549SPaul Moore return ERR_PTR(-ENOMEM); 23008518549SPaul Moore } 23108518549SPaul Moore tmp->name = (char *)result; 23208518549SPaul Moore result = tmp; 23308518549SPaul Moore } else { 23408518549SPaul Moore __putname(result); 23508518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23608518549SPaul Moore } 23708518549SPaul Moore memcpy((char *)result->name, filename, len); 238c4ad8f98SLinus Torvalds result->uptr = NULL; 239c4ad8f98SLinus Torvalds result->aname = NULL; 24055422d0bSPaul Moore result->refcnt = 1; 241fd3522fdSPaul Moore audit_getname(result); 242c4ad8f98SLinus Torvalds 243c4ad8f98SLinus Torvalds return result; 244c4ad8f98SLinus Torvalds } 245c4ad8f98SLinus Torvalds 24691a27b2aSJeff Layton void putname(struct filename *name) 2471da177e4SLinus Torvalds { 24855422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 24955422d0bSPaul Moore 25055422d0bSPaul Moore if (--name->refcnt > 0) 25155422d0bSPaul Moore return; 25255422d0bSPaul Moore 253fd2f7cb5SAl Viro if (name->name != name->iname) { 25455422d0bSPaul Moore __putname(name->name); 25555422d0bSPaul Moore kfree(name); 25655422d0bSPaul Moore } else 25755422d0bSPaul Moore __putname(name); 2581da177e4SLinus Torvalds } 2591da177e4SLinus Torvalds 260e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 261e77819e5SLinus Torvalds { 26284635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 263e77819e5SLinus Torvalds struct posix_acl *acl; 264e77819e5SLinus Torvalds 265e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2663567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2673567866bSAl Viro if (!acl) 268e77819e5SLinus Torvalds return -EAGAIN; 2693567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 270b8a7a3a6SAndreas Gruenbacher if (is_uncached_acl(acl)) 271e77819e5SLinus Torvalds return -ECHILD; 272206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 273e77819e5SLinus Torvalds } 274e77819e5SLinus Torvalds 2752982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2764e34e719SChristoph Hellwig if (IS_ERR(acl)) 2774e34e719SChristoph Hellwig return PTR_ERR(acl); 278e77819e5SLinus Torvalds if (acl) { 279e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 280e77819e5SLinus Torvalds posix_acl_release(acl); 281e77819e5SLinus Torvalds return error; 282e77819e5SLinus Torvalds } 28384635d68SLinus Torvalds #endif 284e77819e5SLinus Torvalds 285e77819e5SLinus Torvalds return -EAGAIN; 286e77819e5SLinus Torvalds } 287e77819e5SLinus Torvalds 2885909ccaaSLinus Torvalds /* 289948409c7SAndreas Gruenbacher * This does the basic permission checking 2905909ccaaSLinus Torvalds */ 2917e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2925909ccaaSLinus Torvalds { 29326cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2945909ccaaSLinus Torvalds 2958e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2965909ccaaSLinus Torvalds mode >>= 6; 2975909ccaaSLinus Torvalds else { 298e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2997e40145eSAl Viro int error = check_acl(inode, mask); 3005909ccaaSLinus Torvalds if (error != -EAGAIN) 3015909ccaaSLinus Torvalds return error; 3025909ccaaSLinus Torvalds } 3035909ccaaSLinus Torvalds 3045909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3055909ccaaSLinus Torvalds mode >>= 3; 3065909ccaaSLinus Torvalds } 3075909ccaaSLinus Torvalds 3085909ccaaSLinus Torvalds /* 3095909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3105909ccaaSLinus Torvalds */ 3119c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3125909ccaaSLinus Torvalds return 0; 3135909ccaaSLinus Torvalds return -EACCES; 3145909ccaaSLinus Torvalds } 3151da177e4SLinus Torvalds 3161da177e4SLinus Torvalds /** 3171da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3181da177e4SLinus Torvalds * @inode: inode to check access rights for 3198fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3201da177e4SLinus Torvalds * 3211da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3221da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3231da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 324b74c79e9SNick Piggin * are used for other things. 325b74c79e9SNick Piggin * 326b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 327b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 328b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3291da177e4SLinus Torvalds */ 3302830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3311da177e4SLinus Torvalds { 3325909ccaaSLinus Torvalds int ret; 3331da177e4SLinus Torvalds 3341da177e4SLinus Torvalds /* 335948409c7SAndreas Gruenbacher * Do the basic permission checks. 3361da177e4SLinus Torvalds */ 3377e40145eSAl Viro ret = acl_permission_check(inode, mask); 3385909ccaaSLinus Torvalds if (ret != -EACCES) 3395909ccaaSLinus Torvalds return ret; 3401da177e4SLinus Torvalds 341d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 342d594e7ecSAl Viro /* DACs are overridable for directories */ 34323adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 344d594e7ecSAl Viro return 0; 345d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34623adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34723adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 348d594e7ecSAl Viro return 0; 349d594e7ecSAl Viro return -EACCES; 350d594e7ecSAl Viro } 3511da177e4SLinus Torvalds /* 3521da177e4SLinus Torvalds * Read/write DACs are always overridable. 353d594e7ecSAl Viro * Executable DACs are overridable when there is 354d594e7ecSAl Viro * at least one exec bit set. 3551da177e4SLinus Torvalds */ 356d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 35723adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3581da177e4SLinus Torvalds return 0; 3591da177e4SLinus Torvalds 3601da177e4SLinus Torvalds /* 3611da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3621da177e4SLinus Torvalds */ 3637ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 364d594e7ecSAl Viro if (mask == MAY_READ) 36523adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3661da177e4SLinus Torvalds return 0; 3671da177e4SLinus Torvalds 3681da177e4SLinus Torvalds return -EACCES; 3691da177e4SLinus Torvalds } 3704d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3711da177e4SLinus Torvalds 3723ddcd056SLinus Torvalds /* 3733ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3743ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3753ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3763ddcd056SLinus Torvalds * permission function, use the fast case". 3773ddcd056SLinus Torvalds */ 3783ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3793ddcd056SLinus Torvalds { 3803ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3813ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3823ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3833ddcd056SLinus Torvalds 3843ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3853ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3863ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3873ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3883ddcd056SLinus Torvalds } 3893ddcd056SLinus Torvalds return generic_permission(inode, mask); 3903ddcd056SLinus Torvalds } 3913ddcd056SLinus Torvalds 392cb23beb5SChristoph Hellwig /** 3930bdaea90SDavid Howells * __inode_permission - Check for access rights to a given inode 3940bdaea90SDavid Howells * @inode: Inode to check permission on 3950bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 396cb23beb5SChristoph Hellwig * 3970bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. 398948409c7SAndreas Gruenbacher * 399948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4000bdaea90SDavid Howells * 4010bdaea90SDavid Howells * This does not check for a read-only file system. You probably want 4020bdaea90SDavid Howells * inode_permission(). 403cb23beb5SChristoph Hellwig */ 4040bdaea90SDavid Howells int __inode_permission(struct inode *inode, int mask) 4051da177e4SLinus Torvalds { 406e6305c43SAl Viro int retval; 4071da177e4SLinus Torvalds 4083ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 4091da177e4SLinus Torvalds /* 4101da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 4111da177e4SLinus Torvalds */ 4121da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 413337684a1SEryu Guan return -EPERM; 4140bd23d09SEric W. Biederman 4150bd23d09SEric W. Biederman /* 4160bd23d09SEric W. Biederman * Updating mtime will likely cause i_uid and i_gid to be 4170bd23d09SEric W. Biederman * written back improperly if their true value is unknown 4180bd23d09SEric W. Biederman * to the vfs. 4190bd23d09SEric W. Biederman */ 4200bd23d09SEric W. Biederman if (HAS_UNMAPPED_ID(inode)) 4210bd23d09SEric W. Biederman return -EACCES; 4221da177e4SLinus Torvalds } 4231da177e4SLinus Torvalds 4243ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 4251da177e4SLinus Torvalds if (retval) 4261da177e4SLinus Torvalds return retval; 4271da177e4SLinus Torvalds 42808ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 42908ce5f16SSerge E. Hallyn if (retval) 43008ce5f16SSerge E. Hallyn return retval; 43108ce5f16SSerge E. Hallyn 432d09ca739SEric Paris return security_inode_permission(inode, mask); 4331da177e4SLinus Torvalds } 434bd5d0856SMiklos Szeredi EXPORT_SYMBOL(__inode_permission); 4351da177e4SLinus Torvalds 436f4d6ff89SAl Viro /** 4370bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 4380bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 43955852635SRandy Dunlap * @inode: Inode to check permission on 4400bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4410bdaea90SDavid Howells * 4420bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4430bdaea90SDavid Howells */ 4440bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4450bdaea90SDavid Howells { 4460bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4470bdaea90SDavid Howells umode_t mode = inode->i_mode; 4480bdaea90SDavid Howells 4490bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 4500bdaea90SDavid Howells if ((sb->s_flags & MS_RDONLY) && 4510bdaea90SDavid Howells (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4520bdaea90SDavid Howells return -EROFS; 4530bdaea90SDavid Howells } 4540bdaea90SDavid Howells return 0; 4550bdaea90SDavid Howells } 4560bdaea90SDavid Howells 4570bdaea90SDavid Howells /** 4580bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4590bdaea90SDavid Howells * @inode: Inode to check permission on 4600bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4610bdaea90SDavid Howells * 4620bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4630bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4640bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4650bdaea90SDavid Howells * 4660bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4670bdaea90SDavid Howells */ 4680bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4690bdaea90SDavid Howells { 4700bdaea90SDavid Howells int retval; 4710bdaea90SDavid Howells 4720bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4730bdaea90SDavid Howells if (retval) 4740bdaea90SDavid Howells return retval; 4750bdaea90SDavid Howells return __inode_permission(inode, mask); 4760bdaea90SDavid Howells } 4774d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4780bdaea90SDavid Howells 4790bdaea90SDavid Howells /** 4805dd784d0SJan Blunck * path_get - get a reference to a path 4815dd784d0SJan Blunck * @path: path to get the reference to 4825dd784d0SJan Blunck * 4835dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4845dd784d0SJan Blunck */ 485dcf787f3SAl Viro void path_get(const struct path *path) 4865dd784d0SJan Blunck { 4875dd784d0SJan Blunck mntget(path->mnt); 4885dd784d0SJan Blunck dget(path->dentry); 4895dd784d0SJan Blunck } 4905dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4915dd784d0SJan Blunck 4925dd784d0SJan Blunck /** 4931d957f9bSJan Blunck * path_put - put a reference to a path 4941d957f9bSJan Blunck * @path: path to put the reference to 4951d957f9bSJan Blunck * 4961d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4971d957f9bSJan Blunck */ 498dcf787f3SAl Viro void path_put(const struct path *path) 4991da177e4SLinus Torvalds { 5001d957f9bSJan Blunck dput(path->dentry); 5011d957f9bSJan Blunck mntput(path->mnt); 5021da177e4SLinus Torvalds } 5031d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 5041da177e4SLinus Torvalds 505894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 5061f55a6ecSAl Viro struct nameidata { 5071f55a6ecSAl Viro struct path path; 5081f55a6ecSAl Viro struct qstr last; 5091f55a6ecSAl Viro struct path root; 5101f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 5111f55a6ecSAl Viro unsigned int flags; 5129883d185SAl Viro unsigned seq, m_seq; 5131f55a6ecSAl Viro int last_type; 5141f55a6ecSAl Viro unsigned depth; 515756daf26SNeilBrown int total_link_count; 516697fc6caSAl Viro struct saved { 517697fc6caSAl Viro struct path link; 518fceef393SAl Viro struct delayed_call done; 519697fc6caSAl Viro const char *name; 5200450b2d1SAl Viro unsigned seq; 521894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5229883d185SAl Viro struct filename *name; 5239883d185SAl Viro struct nameidata *saved; 524fceef393SAl Viro struct inode *link_inode; 5259883d185SAl Viro unsigned root_seq; 5269883d185SAl Viro int dfd; 5271f55a6ecSAl Viro }; 5281f55a6ecSAl Viro 5299883d185SAl Viro static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) 530894bc8c4SAl Viro { 531756daf26SNeilBrown struct nameidata *old = current->nameidata; 532756daf26SNeilBrown p->stack = p->internal; 533c8a53ee5SAl Viro p->dfd = dfd; 534c8a53ee5SAl Viro p->name = name; 535756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 5369883d185SAl Viro p->saved = old; 537756daf26SNeilBrown current->nameidata = p; 538894bc8c4SAl Viro } 539894bc8c4SAl Viro 5409883d185SAl Viro static void restore_nameidata(void) 541894bc8c4SAl Viro { 5429883d185SAl Viro struct nameidata *now = current->nameidata, *old = now->saved; 543756daf26SNeilBrown 544756daf26SNeilBrown current->nameidata = old; 545756daf26SNeilBrown if (old) 546756daf26SNeilBrown old->total_link_count = now->total_link_count; 547e1a63bbcSAl Viro if (now->stack != now->internal) 548756daf26SNeilBrown kfree(now->stack); 549894bc8c4SAl Viro } 550894bc8c4SAl Viro 551894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 552894bc8c4SAl Viro { 553bc40aee0SAl Viro struct saved *p; 554bc40aee0SAl Viro 555bc40aee0SAl Viro if (nd->flags & LOOKUP_RCU) { 556bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 557bc40aee0SAl Viro GFP_ATOMIC); 558bc40aee0SAl Viro if (unlikely(!p)) 559bc40aee0SAl Viro return -ECHILD; 560bc40aee0SAl Viro } else { 561bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 562894bc8c4SAl Viro GFP_KERNEL); 563894bc8c4SAl Viro if (unlikely(!p)) 564894bc8c4SAl Viro return -ENOMEM; 565bc40aee0SAl Viro } 566894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 567894bc8c4SAl Viro nd->stack = p; 568894bc8c4SAl Viro return 0; 569894bc8c4SAl Viro } 570894bc8c4SAl Viro 571397d425dSEric W. Biederman /** 572397d425dSEric W. Biederman * path_connected - Verify that a path->dentry is below path->mnt.mnt_root 573397d425dSEric W. Biederman * @path: nameidate to verify 574397d425dSEric W. Biederman * 575397d425dSEric W. Biederman * Rename can sometimes move a file or directory outside of a bind 576397d425dSEric W. Biederman * mount, path_connected allows those cases to be detected. 577397d425dSEric W. Biederman */ 578397d425dSEric W. Biederman static bool path_connected(const struct path *path) 579397d425dSEric W. Biederman { 580397d425dSEric W. Biederman struct vfsmount *mnt = path->mnt; 581397d425dSEric W. Biederman 582397d425dSEric W. Biederman /* Only bind mounts can have disconnected paths */ 583397d425dSEric W. Biederman if (mnt->mnt_root == mnt->mnt_sb->s_root) 584397d425dSEric W. Biederman return true; 585397d425dSEric W. Biederman 586397d425dSEric W. Biederman return is_subdir(path->dentry, mnt->mnt_root); 587397d425dSEric W. Biederman } 588397d425dSEric W. Biederman 589894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 590894bc8c4SAl Viro { 591da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 592894bc8c4SAl Viro return 0; 593894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 594894bc8c4SAl Viro return 0; 595894bc8c4SAl Viro return __nd_alloc_stack(nd); 596894bc8c4SAl Viro } 597894bc8c4SAl Viro 5987973387aSAl Viro static void drop_links(struct nameidata *nd) 5997973387aSAl Viro { 6007973387aSAl Viro int i = nd->depth; 6017973387aSAl Viro while (i--) { 6027973387aSAl Viro struct saved *last = nd->stack + i; 603fceef393SAl Viro do_delayed_call(&last->done); 604fceef393SAl Viro clear_delayed_call(&last->done); 6057973387aSAl Viro } 6067973387aSAl Viro } 6077973387aSAl Viro 6087973387aSAl Viro static void terminate_walk(struct nameidata *nd) 6097973387aSAl Viro { 6107973387aSAl Viro drop_links(nd); 6117973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 6127973387aSAl Viro int i; 6137973387aSAl Viro path_put(&nd->path); 6147973387aSAl Viro for (i = 0; i < nd->depth; i++) 6157973387aSAl Viro path_put(&nd->stack[i].link); 616102b8af2SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 617102b8af2SAl Viro path_put(&nd->root); 618102b8af2SAl Viro nd->root.mnt = NULL; 619102b8af2SAl Viro } 6207973387aSAl Viro } else { 6217973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 6227973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6237973387aSAl Viro nd->root.mnt = NULL; 6247973387aSAl Viro rcu_read_unlock(); 6257973387aSAl Viro } 6267973387aSAl Viro nd->depth = 0; 6277973387aSAl Viro } 6287973387aSAl Viro 6297973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 6307973387aSAl Viro static bool legitimize_path(struct nameidata *nd, 6317973387aSAl Viro struct path *path, unsigned seq) 6327973387aSAl Viro { 6337973387aSAl Viro int res = __legitimize_mnt(path->mnt, nd->m_seq); 6347973387aSAl Viro if (unlikely(res)) { 6357973387aSAl Viro if (res > 0) 6367973387aSAl Viro path->mnt = NULL; 6377973387aSAl Viro path->dentry = NULL; 6387973387aSAl Viro return false; 6397973387aSAl Viro } 6407973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 6417973387aSAl Viro path->dentry = NULL; 6427973387aSAl Viro return false; 6437973387aSAl Viro } 6447973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6457973387aSAl Viro } 6467973387aSAl Viro 6477973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6487973387aSAl Viro { 6497973387aSAl Viro int i; 6507973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6517973387aSAl Viro struct saved *last = nd->stack + i; 6527973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6537973387aSAl Viro drop_links(nd); 6547973387aSAl Viro nd->depth = i + 1; 6557973387aSAl Viro return false; 6567973387aSAl Viro } 6577973387aSAl Viro } 6587973387aSAl Viro return true; 6597973387aSAl Viro } 6607973387aSAl Viro 66119660af7SAl Viro /* 66231e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 66319660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 66419660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 66557e3715cSMike Marshall * normal reference counts on dentries and vfsmounts to transition to ref-walk 66619660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 66719660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 66819660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 66919660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 67031e6b01fSNick Piggin */ 67131e6b01fSNick Piggin 67231e6b01fSNick Piggin /** 67319660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 67419660af7SAl Viro * @nd: nameidata pathwalk data 67519660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 6766e9918b7SAl Viro * @seq: seq number to check dentry against 67739191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 67831e6b01fSNick Piggin * 67919660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 68019660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 68119660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 6827973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6837973387aSAl Viro * terminate_walk(). 68431e6b01fSNick Piggin */ 6856e9918b7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry, unsigned seq) 68631e6b01fSNick Piggin { 68731e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 68831e6b01fSNick Piggin 68931e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 690e5c832d5SLinus Torvalds 691e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6927973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6937973387aSAl Viro goto out2; 6947973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 6957973387aSAl Viro goto out2; 6967973387aSAl Viro if (unlikely(!lockref_get_not_dead(&parent->d_lockref))) 6977973387aSAl Viro goto out1; 69848a066e7SAl Viro 69915570086SLinus Torvalds /* 70015570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 70115570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 70215570086SLinus Torvalds * 70315570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 70415570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 70515570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 70615570086SLinus Torvalds * since we checked the sequence number of the parent after we got 70715570086SLinus Torvalds * the child sequence number. So we know the parent must still 70815570086SLinus Torvalds * be valid if the child sequence number is still valid. 70915570086SLinus Torvalds */ 71019660af7SAl Viro if (!dentry) { 711e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 712e5c832d5SLinus Torvalds goto out; 71319660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 71419660af7SAl Viro } else { 715e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 716e5c832d5SLinus Torvalds goto out; 7176e9918b7SAl Viro if (read_seqcount_retry(&dentry->d_seq, seq)) 718e5c832d5SLinus Torvalds goto drop_dentry; 71919660af7SAl Viro } 720e5c832d5SLinus Torvalds 721e5c832d5SLinus Torvalds /* 722e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 723e5c832d5SLinus Torvalds * still valid and get it if required. 724e5c832d5SLinus Torvalds */ 725e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 7265a8d87e8SAl Viro if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq))) { 7275a8d87e8SAl Viro rcu_read_unlock(); 7285a8d87e8SAl Viro dput(dentry); 7295a8d87e8SAl Viro return -ECHILD; 7307973387aSAl Viro } 73131e6b01fSNick Piggin } 73231e6b01fSNick Piggin 7338b61e74fSAl Viro rcu_read_unlock(); 73431e6b01fSNick Piggin return 0; 73519660af7SAl Viro 736e5c832d5SLinus Torvalds drop_dentry: 7378b61e74fSAl Viro rcu_read_unlock(); 738e5c832d5SLinus Torvalds dput(dentry); 739d0d27277SLinus Torvalds goto drop_root_mnt; 7407973387aSAl Viro out2: 7417973387aSAl Viro nd->path.mnt = NULL; 7427973387aSAl Viro out1: 7437973387aSAl Viro nd->path.dentry = NULL; 744e5c832d5SLinus Torvalds out: 7458b61e74fSAl Viro rcu_read_unlock(); 746d0d27277SLinus Torvalds drop_root_mnt: 747d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 748d0d27277SLinus Torvalds nd->root.mnt = NULL; 74931e6b01fSNick Piggin return -ECHILD; 75031e6b01fSNick Piggin } 75131e6b01fSNick Piggin 7524ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 75334286d66SNick Piggin { 754a89f8337SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 7554ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 756a89f8337SAl Viro else 757a89f8337SAl Viro return 1; 75834286d66SNick Piggin } 75934286d66SNick Piggin 7609f1fafeeSAl Viro /** 7619f1fafeeSAl Viro * complete_walk - successful completion of path walk 7629f1fafeeSAl Viro * @nd: pointer nameidata 76339159de2SJeff Layton * 7649f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7659f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7669f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7679f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7689f1fafeeSAl Viro * need to drop nd->path. 76939159de2SJeff Layton */ 7709f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 77139159de2SJeff Layton { 77216c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 77339159de2SJeff Layton int status; 77439159de2SJeff Layton 7759f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 7769f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7779f1fafeeSAl Viro nd->root.mnt = NULL; 7786e9918b7SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 77948a066e7SAl Viro return -ECHILD; 78048a066e7SAl Viro } 7819f1fafeeSAl Viro 78216c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 78339159de2SJeff Layton return 0; 78439159de2SJeff Layton 785ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 78616c2cd71SAl Viro return 0; 78716c2cd71SAl Viro 788ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 78939159de2SJeff Layton if (status > 0) 79039159de2SJeff Layton return 0; 79139159de2SJeff Layton 79216c2cd71SAl Viro if (!status) 79339159de2SJeff Layton status = -ESTALE; 79416c2cd71SAl Viro 79539159de2SJeff Layton return status; 79639159de2SJeff Layton } 79739159de2SJeff Layton 79818d8c860SAl Viro static void set_root(struct nameidata *nd) 7992a737871SAl Viro { 80031e6b01fSNick Piggin struct fs_struct *fs = current->fs; 8019e6697e2SAl Viro 8029e6697e2SAl Viro if (nd->flags & LOOKUP_RCU) { 8038f47a016SAl Viro unsigned seq; 804c28cc364SNick Piggin 805c28cc364SNick Piggin do { 806c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 80731e6b01fSNick Piggin nd->root = fs->root; 8088f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 809c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 8109e6697e2SAl Viro } else { 8119e6697e2SAl Viro get_fs_root(fs, &nd->root); 8129e6697e2SAl Viro } 81331e6b01fSNick Piggin } 81431e6b01fSNick Piggin 8151d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 816051d3812SIan Kent { 817051d3812SIan Kent dput(path->dentry); 8184ac91378SJan Blunck if (path->mnt != nd->path.mnt) 819051d3812SIan Kent mntput(path->mnt); 820051d3812SIan Kent } 821051d3812SIan Kent 8227b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8237b9337aaSNick Piggin struct nameidata *nd) 824051d3812SIan Kent { 82531e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8264ac91378SJan Blunck dput(nd->path.dentry); 82731e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8284ac91378SJan Blunck mntput(nd->path.mnt); 8299a229683SHuang Shijie } 83031e6b01fSNick Piggin nd->path.mnt = path->mnt; 8314ac91378SJan Blunck nd->path.dentry = path->dentry; 832051d3812SIan Kent } 833051d3812SIan Kent 834248fb5b9SAl Viro static int nd_jump_root(struct nameidata *nd) 835248fb5b9SAl Viro { 836248fb5b9SAl Viro if (nd->flags & LOOKUP_RCU) { 837248fb5b9SAl Viro struct dentry *d; 838248fb5b9SAl Viro nd->path = nd->root; 839248fb5b9SAl Viro d = nd->path.dentry; 840248fb5b9SAl Viro nd->inode = d->d_inode; 841248fb5b9SAl Viro nd->seq = nd->root_seq; 842248fb5b9SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 843248fb5b9SAl Viro return -ECHILD; 844248fb5b9SAl Viro } else { 845248fb5b9SAl Viro path_put(&nd->path); 846248fb5b9SAl Viro nd->path = nd->root; 847248fb5b9SAl Viro path_get(&nd->path); 848248fb5b9SAl Viro nd->inode = nd->path.dentry->d_inode; 849248fb5b9SAl Viro } 850248fb5b9SAl Viro nd->flags |= LOOKUP_JUMPED; 851248fb5b9SAl Viro return 0; 852248fb5b9SAl Viro } 853248fb5b9SAl Viro 854b5fb63c1SChristoph Hellwig /* 8556b255391SAl Viro * Helper to directly jump to a known parsed path from ->get_link, 856b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 857b5fb63c1SChristoph Hellwig */ 8586e77137bSAl Viro void nd_jump_link(struct path *path) 859b5fb63c1SChristoph Hellwig { 8606e77137bSAl Viro struct nameidata *nd = current->nameidata; 861b5fb63c1SChristoph Hellwig path_put(&nd->path); 862b5fb63c1SChristoph Hellwig 863b5fb63c1SChristoph Hellwig nd->path = *path; 864b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 865b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 866b5fb63c1SChristoph Hellwig } 867b5fb63c1SChristoph Hellwig 868b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 869574197e0SAl Viro { 87021c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 871fceef393SAl Viro do_delayed_call(&last->done); 8726548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 873b9ff4429SAl Viro path_put(&last->link); 874574197e0SAl Viro } 875574197e0SAl Viro 876561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 877561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 878800179c9SKees Cook 879800179c9SKees Cook /** 880800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 88155852635SRandy Dunlap * @nd: nameidata pathwalk data 882800179c9SKees Cook * 883800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 884800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 885800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 886800179c9SKees Cook * processes from failing races against path names that may change out 887800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 888800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 889800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 890800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 891800179c9SKees Cook * 892800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 893800179c9SKees Cook */ 894fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 895800179c9SKees Cook { 896800179c9SKees Cook const struct inode *inode; 897800179c9SKees Cook const struct inode *parent; 8982d7f9e2aSSeth Forshee kuid_t puid; 899800179c9SKees Cook 900800179c9SKees Cook if (!sysctl_protected_symlinks) 901800179c9SKees Cook return 0; 902800179c9SKees Cook 903800179c9SKees Cook /* Allowed if owner and follower match. */ 904fceef393SAl Viro inode = nd->link_inode; 90581abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 906800179c9SKees Cook return 0; 907800179c9SKees Cook 908800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 909aa65fa35SAl Viro parent = nd->inode; 910800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 911800179c9SKees Cook return 0; 912800179c9SKees Cook 913800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 9142d7f9e2aSSeth Forshee puid = parent->i_uid; 9152d7f9e2aSSeth Forshee if (uid_valid(puid) && uid_eq(puid, inode->i_uid)) 916800179c9SKees Cook return 0; 917800179c9SKees Cook 91831956502SAl Viro if (nd->flags & LOOKUP_RCU) 91931956502SAl Viro return -ECHILD; 92031956502SAl Viro 9211cf2665bSAl Viro audit_log_link_denied("follow_link", &nd->stack[0].link); 922800179c9SKees Cook return -EACCES; 923800179c9SKees Cook } 924800179c9SKees Cook 925800179c9SKees Cook /** 926800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 927800179c9SKees Cook * @inode: the source inode to hardlink from 928800179c9SKees Cook * 929800179c9SKees Cook * Return false if at least one of the following conditions: 930800179c9SKees Cook * - inode is not a regular file 931800179c9SKees Cook * - inode is setuid 932800179c9SKees Cook * - inode is setgid and group-exec 933800179c9SKees Cook * - access failure for read and write 934800179c9SKees Cook * 935800179c9SKees Cook * Otherwise returns true. 936800179c9SKees Cook */ 937800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 938800179c9SKees Cook { 939800179c9SKees Cook umode_t mode = inode->i_mode; 940800179c9SKees Cook 941800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 942800179c9SKees Cook if (!S_ISREG(mode)) 943800179c9SKees Cook return false; 944800179c9SKees Cook 945800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 946800179c9SKees Cook if (mode & S_ISUID) 947800179c9SKees Cook return false; 948800179c9SKees Cook 949800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 950800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 951800179c9SKees Cook return false; 952800179c9SKees Cook 953800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 954800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 955800179c9SKees Cook return false; 956800179c9SKees Cook 957800179c9SKees Cook return true; 958800179c9SKees Cook } 959800179c9SKees Cook 960800179c9SKees Cook /** 961800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 962800179c9SKees Cook * @link: the source to hardlink from 963800179c9SKees Cook * 964800179c9SKees Cook * Block hardlink when all of: 965800179c9SKees Cook * - sysctl_protected_hardlinks enabled 966800179c9SKees Cook * - fsuid does not match inode 967800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 968f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 969800179c9SKees Cook * 970800179c9SKees Cook * Returns 0 if successful, -ve on error. 971800179c9SKees Cook */ 972800179c9SKees Cook static int may_linkat(struct path *link) 973800179c9SKees Cook { 974800179c9SKees Cook struct inode *inode; 975800179c9SKees Cook 976800179c9SKees Cook if (!sysctl_protected_hardlinks) 977800179c9SKees Cook return 0; 978800179c9SKees Cook 979800179c9SKees Cook inode = link->dentry->d_inode; 980800179c9SKees Cook 981800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 982800179c9SKees Cook * otherwise, it must be a safe source. 983800179c9SKees Cook */ 984f2ca3796SDirk Steinmetz if (inode_owner_or_capable(inode) || safe_hardlink_source(inode)) 985800179c9SKees Cook return 0; 986800179c9SKees Cook 987a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 988800179c9SKees Cook return -EPERM; 989800179c9SKees Cook } 990800179c9SKees Cook 9913b2e7f75SAl Viro static __always_inline 9923b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 9931da177e4SLinus Torvalds { 994ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 9951cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 996fceef393SAl Viro struct inode *inode = nd->link_inode; 9976d7b5aaeSAl Viro int error; 9980a959df5SAl Viro const char *res; 9991da177e4SLinus Torvalds 10008fa9dd24SNeilBrown if (!(nd->flags & LOOKUP_RCU)) { 10018fa9dd24SNeilBrown touch_atime(&last->link); 10028fa9dd24SNeilBrown cond_resched(); 1003598e3c8fSMiklos Szeredi } else if (atime_needs_update_rcu(&last->link, inode)) { 10048fa9dd24SNeilBrown if (unlikely(unlazy_walk(nd, NULL, 0))) 10058fa9dd24SNeilBrown return ERR_PTR(-ECHILD); 10068fa9dd24SNeilBrown touch_atime(&last->link); 10078fa9dd24SNeilBrown } 10088fa9dd24SNeilBrown 1009bda0be7aSNeilBrown error = security_inode_follow_link(dentry, inode, 1010bda0be7aSNeilBrown nd->flags & LOOKUP_RCU); 1011bda0be7aSNeilBrown if (unlikely(error)) 10126920a440SAl Viro return ERR_PTR(error); 101336f3b4f6SAl Viro 101486acdca1SAl Viro nd->last_type = LAST_BIND; 1015d4dee48bSAl Viro res = inode->i_link; 1016d4dee48bSAl Viro if (!res) { 1017fceef393SAl Viro const char * (*get)(struct dentry *, struct inode *, 1018fceef393SAl Viro struct delayed_call *); 1019fceef393SAl Viro get = inode->i_op->get_link; 10208c1b4566SAl Viro if (nd->flags & LOOKUP_RCU) { 1021fceef393SAl Viro res = get(NULL, inode, &last->done); 10226b255391SAl Viro if (res == ERR_PTR(-ECHILD)) { 10238c1b4566SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 10248c1b4566SAl Viro return ERR_PTR(-ECHILD); 1025fceef393SAl Viro res = get(dentry, inode, &last->done); 10268c1b4566SAl Viro } 10276b255391SAl Viro } else { 1028fceef393SAl Viro res = get(dentry, inode, &last->done); 10296b255391SAl Viro } 1030fceef393SAl Viro if (IS_ERR_OR_NULL(res)) 1031fab51e8aSAl Viro return res; 10320a959df5SAl Viro } 1033fab51e8aSAl Viro if (*res == '/') { 1034fab51e8aSAl Viro if (!nd->root.mnt) 1035fab51e8aSAl Viro set_root(nd); 1036248fb5b9SAl Viro if (unlikely(nd_jump_root(nd))) 1037fab51e8aSAl Viro return ERR_PTR(-ECHILD); 1038fab51e8aSAl Viro while (unlikely(*++res == '/')) 1039fab51e8aSAl Viro ; 1040fab51e8aSAl Viro } 1041fab51e8aSAl Viro if (!*res) 1042fab51e8aSAl Viro res = NULL; 10430a959df5SAl Viro return res; 10440a959df5SAl Viro } 10456d7b5aaeSAl Viro 1046f015f126SDavid Howells /* 1047f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1048f015f126SDavid Howells * 1049f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1050f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1051f015f126SDavid Howells * Up is towards /. 1052f015f126SDavid Howells * 1053f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1054f015f126SDavid Howells * root. 1055f015f126SDavid Howells */ 1056bab77ebfSAl Viro int follow_up(struct path *path) 10571da177e4SLinus Torvalds { 10580714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 10590714a533SAl Viro struct mount *parent; 10601da177e4SLinus Torvalds struct dentry *mountpoint; 106199b7db7bSNick Piggin 106248a066e7SAl Viro read_seqlock_excl(&mount_lock); 10630714a533SAl Viro parent = mnt->mnt_parent; 10643c0a6163SAl Viro if (parent == mnt) { 106548a066e7SAl Viro read_sequnlock_excl(&mount_lock); 10661da177e4SLinus Torvalds return 0; 10671da177e4SLinus Torvalds } 10680714a533SAl Viro mntget(&parent->mnt); 1069a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 107048a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1071bab77ebfSAl Viro dput(path->dentry); 1072bab77ebfSAl Viro path->dentry = mountpoint; 1073bab77ebfSAl Viro mntput(path->mnt); 10740714a533SAl Viro path->mnt = &parent->mnt; 10751da177e4SLinus Torvalds return 1; 10761da177e4SLinus Torvalds } 10774d359507SAl Viro EXPORT_SYMBOL(follow_up); 10781da177e4SLinus Torvalds 1079b5c84bf6SNick Piggin /* 10809875cf80SDavid Howells * Perform an automount 10819875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 10829875cf80SDavid Howells * were called with. 10831da177e4SLinus Torvalds */ 1084756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 10859875cf80SDavid Howells bool *need_mntput) 108631e6b01fSNick Piggin { 10879875cf80SDavid Howells struct vfsmount *mnt; 1088aeaa4a79SEric W. Biederman const struct cred *old_cred; 1089ea5b778aSDavid Howells int err; 10909875cf80SDavid Howells 10919875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 10929875cf80SDavid Howells return -EREMOTE; 10939875cf80SDavid Howells 10940ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 10950ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 10960ec26fd0SMiklos Szeredi * the name. 10970ec26fd0SMiklos Szeredi * 10980ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 10995a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 11000ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 11010ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 11020ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 11030ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 11045a30d8a2SDavid Howells */ 1105756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 1106d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 11075a30d8a2SDavid Howells path->dentry->d_inode) 11089875cf80SDavid Howells return -EISDIR; 11090ec26fd0SMiklos Szeredi 1110aeaa4a79SEric W. Biederman if (path->dentry->d_sb->s_user_ns != &init_user_ns) 1111aeaa4a79SEric W. Biederman return -EACCES; 1112aeaa4a79SEric W. Biederman 1113756daf26SNeilBrown nd->total_link_count++; 1114756daf26SNeilBrown if (nd->total_link_count >= 40) 11159875cf80SDavid Howells return -ELOOP; 11169875cf80SDavid Howells 1117aeaa4a79SEric W. Biederman old_cred = override_creds(&init_cred); 11189875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 1119aeaa4a79SEric W. Biederman revert_creds(old_cred); 11209875cf80SDavid Howells if (IS_ERR(mnt)) { 11219875cf80SDavid Howells /* 11229875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 11239875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 11249875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 11259875cf80SDavid Howells * 11269875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 11279875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 11289875cf80SDavid Howells * the path is inaccessible and we should say so. 11299875cf80SDavid Howells */ 1130756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 11319875cf80SDavid Howells return -EREMOTE; 11329875cf80SDavid Howells return PTR_ERR(mnt); 113331e6b01fSNick Piggin } 1134ea5b778aSDavid Howells 11359875cf80SDavid Howells if (!mnt) /* mount collision */ 11369875cf80SDavid Howells return 0; 11379875cf80SDavid Howells 11388aef1884SAl Viro if (!*need_mntput) { 11398aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 11408aef1884SAl Viro mntget(path->mnt); 11418aef1884SAl Viro *need_mntput = true; 11428aef1884SAl Viro } 114319a167afSAl Viro err = finish_automount(mnt, path); 1144ea5b778aSDavid Howells 1145ea5b778aSDavid Howells switch (err) { 1146ea5b778aSDavid Howells case -EBUSY: 1147ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 114819a167afSAl Viro return 0; 1149ea5b778aSDavid Howells case 0: 11508aef1884SAl Viro path_put(path); 11519875cf80SDavid Howells path->mnt = mnt; 11529875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 11539875cf80SDavid Howells return 0; 115419a167afSAl Viro default: 115519a167afSAl Viro return err; 11569875cf80SDavid Howells } 115719a167afSAl Viro 1158ea5b778aSDavid Howells } 11599875cf80SDavid Howells 11609875cf80SDavid Howells /* 11619875cf80SDavid Howells * Handle a dentry that is managed in some way. 1162cc53ce53SDavid Howells * - Flagged for transit management (autofs) 11639875cf80SDavid Howells * - Flagged as mountpoint 11649875cf80SDavid Howells * - Flagged as automount point 11659875cf80SDavid Howells * 11669875cf80SDavid Howells * This may only be called in refwalk mode. 11679875cf80SDavid Howells * 11689875cf80SDavid Howells * Serialization is taken care of in namespace.c 11699875cf80SDavid Howells */ 1170756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 11719875cf80SDavid Howells { 11728aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 11739875cf80SDavid Howells unsigned managed; 11749875cf80SDavid Howells bool need_mntput = false; 11758aef1884SAl Viro int ret = 0; 11769875cf80SDavid Howells 11779875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 11789875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 11799875cf80SDavid Howells * the components of that value change under us */ 11809875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 11819875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 11829875cf80SDavid Howells unlikely(managed != 0)) { 1183cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1184cc53ce53SDavid Howells * being held. */ 1185cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1186cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1187cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1188fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1189cc53ce53SDavid Howells if (ret < 0) 11908aef1884SAl Viro break; 1191cc53ce53SDavid Howells } 1192cc53ce53SDavid Howells 11939875cf80SDavid Howells /* Transit to a mounted filesystem. */ 11949875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 11959875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 11969875cf80SDavid Howells if (mounted) { 11979875cf80SDavid Howells dput(path->dentry); 11989875cf80SDavid Howells if (need_mntput) 1199463ffb2eSAl Viro mntput(path->mnt); 1200463ffb2eSAl Viro path->mnt = mounted; 1201463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 12029875cf80SDavid Howells need_mntput = true; 12039875cf80SDavid Howells continue; 1204463ffb2eSAl Viro } 1205463ffb2eSAl Viro 12069875cf80SDavid Howells /* Something is mounted on this dentry in another 12079875cf80SDavid Howells * namespace and/or whatever was mounted there in this 120848a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 120948a066e7SAl Viro * get it */ 12101da177e4SLinus Torvalds } 12119875cf80SDavid Howells 12129875cf80SDavid Howells /* Handle an automount point */ 12139875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1214756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 12159875cf80SDavid Howells if (ret < 0) 12168aef1884SAl Viro break; 12179875cf80SDavid Howells continue; 12189875cf80SDavid Howells } 12199875cf80SDavid Howells 12209875cf80SDavid Howells /* We didn't change the current path point */ 12219875cf80SDavid Howells break; 12229875cf80SDavid Howells } 12238aef1884SAl Viro 12248aef1884SAl Viro if (need_mntput && path->mnt == mnt) 12258aef1884SAl Viro mntput(path->mnt); 1226e9742b53SAl Viro if (ret == -EISDIR || !ret) 1227e9742b53SAl Viro ret = 1; 12288402752eSAl Viro if (need_mntput) 12298402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 12308402752eSAl Viro if (unlikely(ret < 0)) 12318402752eSAl Viro path_put_conditional(path, nd); 12328402752eSAl Viro return ret; 12331da177e4SLinus Torvalds } 12341da177e4SLinus Torvalds 1235cc53ce53SDavid Howells int follow_down_one(struct path *path) 12361da177e4SLinus Torvalds { 12371da177e4SLinus Torvalds struct vfsmount *mounted; 12381da177e4SLinus Torvalds 12391c755af4SAl Viro mounted = lookup_mnt(path); 12401da177e4SLinus Torvalds if (mounted) { 12419393bd07SAl Viro dput(path->dentry); 12429393bd07SAl Viro mntput(path->mnt); 12439393bd07SAl Viro path->mnt = mounted; 12449393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12451da177e4SLinus Torvalds return 1; 12461da177e4SLinus Torvalds } 12471da177e4SLinus Torvalds return 0; 12481da177e4SLinus Torvalds } 12494d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12501da177e4SLinus Torvalds 1251fb5f51c7SIan Kent static inline int managed_dentry_rcu(const struct path *path) 125262a7375eSIan Kent { 1253fb5f51c7SIan Kent return (path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1254fb5f51c7SIan Kent path->dentry->d_op->d_manage(path, true) : 0; 125562a7375eSIan Kent } 125662a7375eSIan Kent 12579875cf80SDavid Howells /* 1258287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1259287548e4SAl Viro * we meet a managed dentry that would need blocking. 12609875cf80SDavid Howells */ 12619875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1262254cf582SAl Viro struct inode **inode, unsigned *seqp) 12639875cf80SDavid Howells { 126462a7375eSIan Kent for (;;) { 1265c7105365SAl Viro struct mount *mounted; 126662a7375eSIan Kent /* 126762a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 126862a7375eSIan Kent * that wants to block transit. 126962a7375eSIan Kent */ 1270fb5f51c7SIan Kent switch (managed_dentry_rcu(path)) { 1271b8faf035SNeilBrown case -ECHILD: 1272b8faf035SNeilBrown default: 1273ab90911fSDavid Howells return false; 1274b8faf035SNeilBrown case -EISDIR: 1275b8faf035SNeilBrown return true; 1276b8faf035SNeilBrown case 0: 1277b8faf035SNeilBrown break; 1278b8faf035SNeilBrown } 127962a7375eSIan Kent 128062a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1281b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 128262a7375eSIan Kent 1283474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 12849875cf80SDavid Howells if (!mounted) 12859875cf80SDavid Howells break; 1286c7105365SAl Viro path->mnt = &mounted->mnt; 1287c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1288a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1289254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 129059430262SLinus Torvalds /* 129159430262SLinus Torvalds * Update the inode too. We don't need to re-check the 129259430262SLinus Torvalds * dentry sequence number here after this d_inode read, 129359430262SLinus Torvalds * because a mount-point is always pinned. 129459430262SLinus Torvalds */ 129559430262SLinus Torvalds *inode = path->dentry->d_inode; 12969875cf80SDavid Howells } 1297f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1298b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1299287548e4SAl Viro } 1300287548e4SAl Viro 130131e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 130231e6b01fSNick Piggin { 13034023bfc9SAl Viro struct inode *inode = nd->inode; 130431e6b01fSNick Piggin 130531e6b01fSNick Piggin while (1) { 1306aed434adSAl Viro if (path_equal(&nd->path, &nd->root)) 130731e6b01fSNick Piggin break; 130831e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 130931e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 131031e6b01fSNick Piggin struct dentry *parent = old->d_parent; 131131e6b01fSNick Piggin unsigned seq; 131231e6b01fSNick Piggin 13134023bfc9SAl Viro inode = parent->d_inode; 131431e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 1315aed434adSAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 1316aed434adSAl Viro return -ECHILD; 131731e6b01fSNick Piggin nd->path.dentry = parent; 131831e6b01fSNick Piggin nd->seq = seq; 1319397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 1320397d425dSEric W. Biederman return -ENOENT; 132131e6b01fSNick Piggin break; 1322aed434adSAl Viro } else { 1323aed434adSAl Viro struct mount *mnt = real_mount(nd->path.mnt); 1324aed434adSAl Viro struct mount *mparent = mnt->mnt_parent; 1325aed434adSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1326aed434adSAl Viro struct inode *inode2 = mountpoint->d_inode; 1327aed434adSAl Viro unsigned seq = read_seqcount_begin(&mountpoint->d_seq); 1328aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1329aed434adSAl Viro return -ECHILD; 1330aed434adSAl Viro if (&mparent->mnt == nd->path.mnt) 133131e6b01fSNick Piggin break; 1332aed434adSAl Viro /* we know that mountpoint was pinned */ 1333aed434adSAl Viro nd->path.dentry = mountpoint; 1334aed434adSAl Viro nd->path.mnt = &mparent->mnt; 1335aed434adSAl Viro inode = inode2; 1336aed434adSAl Viro nd->seq = seq; 133731e6b01fSNick Piggin } 1338aed434adSAl Viro } 1339aed434adSAl Viro while (unlikely(d_mountpoint(nd->path.dentry))) { 1340b37199e6SAl Viro struct mount *mounted; 1341b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1342aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1343aed434adSAl Viro return -ECHILD; 1344b37199e6SAl Viro if (!mounted) 1345b37199e6SAl Viro break; 1346b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1347b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 13484023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1349b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1350b37199e6SAl Viro } 13514023bfc9SAl Viro nd->inode = inode; 135231e6b01fSNick Piggin return 0; 135331e6b01fSNick Piggin } 135431e6b01fSNick Piggin 13559875cf80SDavid Howells /* 1356cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1357cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1358cc53ce53SDavid Howells * caller is permitted to proceed or not. 1359cc53ce53SDavid Howells */ 13607cc90cc3SAl Viro int follow_down(struct path *path) 1361cc53ce53SDavid Howells { 1362cc53ce53SDavid Howells unsigned managed; 1363cc53ce53SDavid Howells int ret; 1364cc53ce53SDavid Howells 1365cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1366cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1367cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1368cc53ce53SDavid Howells * being held. 1369cc53ce53SDavid Howells * 1370cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1371cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1372cc53ce53SDavid Howells * other than its daemon the right to mount on its 1373cc53ce53SDavid Howells * superstructure. 1374cc53ce53SDavid Howells * 1375cc53ce53SDavid Howells * The filesystem may sleep at this point. 1376cc53ce53SDavid Howells */ 1377cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1378cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1379cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1380fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1381cc53ce53SDavid Howells if (ret < 0) 1382cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1383cc53ce53SDavid Howells } 1384cc53ce53SDavid Howells 1385cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1386cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1387cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1388cc53ce53SDavid Howells if (!mounted) 1389cc53ce53SDavid Howells break; 1390cc53ce53SDavid Howells dput(path->dentry); 1391cc53ce53SDavid Howells mntput(path->mnt); 1392cc53ce53SDavid Howells path->mnt = mounted; 1393cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1394cc53ce53SDavid Howells continue; 1395cc53ce53SDavid Howells } 1396cc53ce53SDavid Howells 1397cc53ce53SDavid Howells /* Don't handle automount points here */ 1398cc53ce53SDavid Howells break; 1399cc53ce53SDavid Howells } 1400cc53ce53SDavid Howells return 0; 1401cc53ce53SDavid Howells } 14024d359507SAl Viro EXPORT_SYMBOL(follow_down); 1403cc53ce53SDavid Howells 1404cc53ce53SDavid Howells /* 14059875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 14069875cf80SDavid Howells */ 14079875cf80SDavid Howells static void follow_mount(struct path *path) 14089875cf80SDavid Howells { 14099875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 14109875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 14119875cf80SDavid Howells if (!mounted) 14129875cf80SDavid Howells break; 14139875cf80SDavid Howells dput(path->dentry); 14149875cf80SDavid Howells mntput(path->mnt); 14159875cf80SDavid Howells path->mnt = mounted; 14169875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 14179875cf80SDavid Howells } 14189875cf80SDavid Howells } 14199875cf80SDavid Howells 1420eedf265aSEric W. Biederman static int path_parent_directory(struct path *path) 1421eedf265aSEric W. Biederman { 1422eedf265aSEric W. Biederman struct dentry *old = path->dentry; 1423eedf265aSEric W. Biederman /* rare case of legitimate dget_parent()... */ 1424eedf265aSEric W. Biederman path->dentry = dget_parent(path->dentry); 1425eedf265aSEric W. Biederman dput(old); 1426eedf265aSEric W. Biederman if (unlikely(!path_connected(path))) 1427eedf265aSEric W. Biederman return -ENOENT; 1428eedf265aSEric W. Biederman return 0; 1429eedf265aSEric W. Biederman } 1430eedf265aSEric W. Biederman 1431397d425dSEric W. Biederman static int follow_dotdot(struct nameidata *nd) 14321da177e4SLinus Torvalds { 14331da177e4SLinus Torvalds while(1) { 14342a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 14352a737871SAl Viro nd->path.mnt == nd->root.mnt) { 14361da177e4SLinus Torvalds break; 14371da177e4SLinus Torvalds } 14384ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 1439eedf265aSEric W. Biederman int ret = path_parent_directory(&nd->path); 1440eedf265aSEric W. Biederman if (ret) 1441eedf265aSEric W. Biederman return ret; 14421da177e4SLinus Torvalds break; 14431da177e4SLinus Torvalds } 14443088dd70SAl Viro if (!follow_up(&nd->path)) 14451da177e4SLinus Torvalds break; 14461da177e4SLinus Torvalds } 144779ed0226SAl Viro follow_mount(&nd->path); 144831e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 1449397d425dSEric W. Biederman return 0; 14501da177e4SLinus Torvalds } 14511da177e4SLinus Torvalds 14521da177e4SLinus Torvalds /* 1453f4fdace9SOleg Drokin * This looks up the name in dcache and possibly revalidates the found dentry. 1454f4fdace9SOleg Drokin * NULL is returned if the dentry does not exist in the cache. 1455baa03890SNick Piggin */ 1456e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1457e3c13928SAl Viro struct dentry *dir, 14586c51e513SAl Viro unsigned int flags) 1459baa03890SNick Piggin { 1460a89f8337SAl Viro struct dentry *dentry = d_lookup(dir, name); 1461bad61189SMiklos Szeredi if (dentry) { 1462a89f8337SAl Viro int error = d_revalidate(dentry, flags); 1463bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 146474ff0ffcSAl Viro if (!error) 14655542aa2fSEric W. Biederman d_invalidate(dentry); 1466bad61189SMiklos Szeredi dput(dentry); 146774ff0ffcSAl Viro return ERR_PTR(error); 1468bad61189SMiklos Szeredi } 1469bad61189SMiklos Szeredi } 1470baa03890SNick Piggin return dentry; 1471baa03890SNick Piggin } 1472baa03890SNick Piggin 1473baa03890SNick Piggin /* 147413a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 147513a2c3beSJ. Bruce Fields * unhashed. 1476bad61189SMiklos Szeredi * 1477bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 147844396f4bSJosef Bacik */ 1479bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 148072bd866aSAl Viro unsigned int flags) 148144396f4bSJosef Bacik { 148244396f4bSJosef Bacik struct dentry *old; 148344396f4bSJosef Bacik 148444396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1485bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1486e188dc02SMiklos Szeredi dput(dentry); 148744396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1488e188dc02SMiklos Szeredi } 148944396f4bSJosef Bacik 149072bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 149144396f4bSJosef Bacik if (unlikely(old)) { 149244396f4bSJosef Bacik dput(dentry); 149344396f4bSJosef Bacik dentry = old; 149444396f4bSJosef Bacik } 149544396f4bSJosef Bacik return dentry; 149644396f4bSJosef Bacik } 149744396f4bSJosef Bacik 1498e3c13928SAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 149972bd866aSAl Viro struct dentry *base, unsigned int flags) 1500a3255546SAl Viro { 15016c51e513SAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 1502a3255546SAl Viro 15036c51e513SAl Viro if (dentry) 1504a3255546SAl Viro return dentry; 1505bad61189SMiklos Szeredi 15066c51e513SAl Viro dentry = d_alloc(base, name); 15076c51e513SAl Viro if (unlikely(!dentry)) 15086c51e513SAl Viro return ERR_PTR(-ENOMEM); 15096c51e513SAl Viro 151072bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1511a3255546SAl Viro } 1512a3255546SAl Viro 1513e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 1514254cf582SAl Viro struct path *path, struct inode **inode, 1515254cf582SAl Viro unsigned *seqp) 15161da177e4SLinus Torvalds { 15174ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 151831e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 15195a18fff2SAl Viro int status = 1; 15209875cf80SDavid Howells int err; 15219875cf80SDavid Howells 15223cac260aSAl Viro /* 1523b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 15245d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 15255d0f49c1SAl Viro * going to fall back to non-racy lookup. 1526b04f784eSNick Piggin */ 152731e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 152831e6b01fSNick Piggin unsigned seq; 1529766c4cbfSAl Viro bool negative; 1530da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15315d0f49c1SAl Viro if (unlikely(!dentry)) { 15325d0f49c1SAl Viro if (unlazy_walk(nd, NULL, 0)) 15335d0f49c1SAl Viro return -ECHILD; 1534e9742b53SAl Viro return 0; 15355d0f49c1SAl Viro } 15365a18fff2SAl Viro 153712f8ad4bSLinus Torvalds /* 153812f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 153912f8ad4bSLinus Torvalds * the dentry name information from lookup. 154012f8ad4bSLinus Torvalds */ 154163afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1542766c4cbfSAl Viro negative = d_is_negative(dentry); 15435d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 154412f8ad4bSLinus Torvalds return -ECHILD; 154512f8ad4bSLinus Torvalds 154612f8ad4bSLinus Torvalds /* 154712f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 154812f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 154912f8ad4bSLinus Torvalds * 155012f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 155112f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 155212f8ad4bSLinus Torvalds */ 15535d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 155431e6b01fSNick Piggin return -ECHILD; 15555a18fff2SAl Viro 1556254cf582SAl Viro *seqp = seq; 15574ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 1558209a7fb2SAl Viro if (likely(status > 0)) { 1559daf3761cSTrond Myklebust /* 1560daf3761cSTrond Myklebust * Note: do negative dentry check after revalidation in 1561daf3761cSTrond Myklebust * case that drops it. 1562daf3761cSTrond Myklebust */ 15635d0f49c1SAl Viro if (unlikely(negative)) 1564daf3761cSTrond Myklebust return -ENOENT; 156531e6b01fSNick Piggin path->mnt = mnt; 156631e6b01fSNick Piggin path->dentry = dentry; 1567254cf582SAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 1568e9742b53SAl Viro return 1; 1569209a7fb2SAl Viro } 1570254cf582SAl Viro if (unlazy_walk(nd, dentry, seq)) 15715a18fff2SAl Viro return -ECHILD; 1572209a7fb2SAl Viro if (unlikely(status == -ECHILD)) 1573209a7fb2SAl Viro /* we'd been told to redo it in non-rcu mode */ 1574209a7fb2SAl Viro status = d_revalidate(dentry, nd->flags); 15755a18fff2SAl Viro } else { 1576e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 157781e6f520SAl Viro if (unlikely(!dentry)) 1578e9742b53SAl Viro return 0; 15794ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15805d0f49c1SAl Viro } 15815a18fff2SAl Viro if (unlikely(status <= 0)) { 1582e9742b53SAl Viro if (!status) 15835d0f49c1SAl Viro d_invalidate(dentry); 15845a18fff2SAl Viro dput(dentry); 15855a18fff2SAl Viro return status; 15865a18fff2SAl Viro } 1587766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1588766c4cbfSAl Viro dput(dentry); 1589766c4cbfSAl Viro return -ENOENT; 1590766c4cbfSAl Viro } 15915d0f49c1SAl Viro 15921da177e4SLinus Torvalds path->mnt = mnt; 15931da177e4SLinus Torvalds path->dentry = dentry; 1594756daf26SNeilBrown err = follow_managed(path, nd); 1595e9742b53SAl Viro if (likely(err > 0)) 159663afdfc7SDavid Howells *inode = d_backing_inode(path->dentry); 15978402752eSAl Viro return err; 1598697f514dSMiklos Szeredi } 1599697f514dSMiklos Szeredi 1600697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1601e3c13928SAl Viro static struct dentry *lookup_slow(const struct qstr *name, 1602e3c13928SAl Viro struct dentry *dir, 1603e3c13928SAl Viro unsigned int flags) 1604697f514dSMiklos Szeredi { 160594bdd655SAl Viro struct dentry *dentry = ERR_PTR(-ENOENT), *old; 16061936386eSAl Viro struct inode *inode = dir->d_inode; 1607d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 16081936386eSAl Viro 16099902af79SAl Viro inode_lock_shared(inode); 16101936386eSAl Viro /* Don't go there if it's already dead */ 161194bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 161294bdd655SAl Viro goto out; 161394bdd655SAl Viro again: 1614d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 161594bdd655SAl Viro if (IS_ERR(dentry)) 161694bdd655SAl Viro goto out; 161794bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1618a89f8337SAl Viro if (!(flags & LOOKUP_NO_REVAL)) { 1619949a852eSAl Viro int error = d_revalidate(dentry, flags); 1620949a852eSAl Viro if (unlikely(error <= 0)) { 162194bdd655SAl Viro if (!error) { 1622949a852eSAl Viro d_invalidate(dentry); 1623949a852eSAl Viro dput(dentry); 162494bdd655SAl Viro goto again; 162594bdd655SAl Viro } 162694bdd655SAl Viro dput(dentry); 1627949a852eSAl Viro dentry = ERR_PTR(error); 1628949a852eSAl Viro } 1629949a852eSAl Viro } 163094bdd655SAl Viro } else { 16311936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 163285c7f810SAl Viro d_lookup_done(dentry); 16331936386eSAl Viro if (unlikely(old)) { 16341936386eSAl Viro dput(dentry); 16351936386eSAl Viro dentry = old; 1636949a852eSAl Viro } 1637949a852eSAl Viro } 163894bdd655SAl Viro out: 16399902af79SAl Viro inode_unlock_shared(inode); 1640e3c13928SAl Viro return dentry; 16411da177e4SLinus Torvalds } 16421da177e4SLinus Torvalds 164352094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 164452094c8aSAl Viro { 164552094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16464ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 164752094c8aSAl Viro if (err != -ECHILD) 164852094c8aSAl Viro return err; 16496e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 165052094c8aSAl Viro return -ECHILD; 165152094c8aSAl Viro } 16524ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 165352094c8aSAl Viro } 165452094c8aSAl Viro 16559856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 16569856fa1bSAl Viro { 16579856fa1bSAl Viro if (type == LAST_DOTDOT) { 16589e6697e2SAl Viro if (!nd->root.mnt) 16599e6697e2SAl Viro set_root(nd); 16609856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 166170291aecSAl Viro return follow_dotdot_rcu(nd); 16629856fa1bSAl Viro } else 1663397d425dSEric W. Biederman return follow_dotdot(nd); 16649856fa1bSAl Viro } 16659856fa1bSAl Viro return 0; 16669856fa1bSAl Viro } 16679856fa1bSAl Viro 1668181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1669181548c0SAl Viro struct inode *inode, unsigned seq) 1670d63ff28fSAl Viro { 1671626de996SAl Viro int error; 16721cf2665bSAl Viro struct saved *last; 1673756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1674626de996SAl Viro path_to_nameidata(link, nd); 1675626de996SAl Viro return -ELOOP; 1676626de996SAl Viro } 1677bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1678cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1679cd179f44SAl Viro mntget(link->mnt); 16807973387aSAl Viro } 1681626de996SAl Viro error = nd_alloc_stack(nd); 1682626de996SAl Viro if (unlikely(error)) { 1683bc40aee0SAl Viro if (error == -ECHILD) { 1684ad1633a1SAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 1685ad1633a1SAl Viro drop_links(nd); 1686ad1633a1SAl Viro nd->depth = 0; 1687ad1633a1SAl Viro nd->flags &= ~LOOKUP_RCU; 1688ad1633a1SAl Viro nd->path.mnt = NULL; 1689ad1633a1SAl Viro nd->path.dentry = NULL; 1690ad1633a1SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1691ad1633a1SAl Viro nd->root.mnt = NULL; 1692ad1633a1SAl Viro rcu_read_unlock(); 1693ad1633a1SAl Viro } else if (likely(unlazy_walk(nd, NULL, 0)) == 0) 1694bc40aee0SAl Viro error = nd_alloc_stack(nd); 1695bc40aee0SAl Viro } 1696bc40aee0SAl Viro if (error) { 1697cd179f44SAl Viro path_put(link); 1698626de996SAl Viro return error; 1699626de996SAl Viro } 1700bc40aee0SAl Viro } 1701626de996SAl Viro 1702ab104923SAl Viro last = nd->stack + nd->depth++; 17031cf2665bSAl Viro last->link = *link; 1704fceef393SAl Viro clear_delayed_call(&last->done); 1705fceef393SAl Viro nd->link_inode = inode; 17060450b2d1SAl Viro last->seq = seq; 1707d63ff28fSAl Viro return 1; 1708d63ff28fSAl Viro } 1709d63ff28fSAl Viro 17108f64fb1cSAl Viro enum {WALK_FOLLOW = 1, WALK_MORE = 2}; 171131d66bcdSAl Viro 17123ddcd056SLinus Torvalds /* 17133ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 17143ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 17153ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 17163ddcd056SLinus Torvalds * for the common case. 17173ddcd056SLinus Torvalds */ 17188f64fb1cSAl Viro static inline int step_into(struct nameidata *nd, struct path *path, 17198f64fb1cSAl Viro int flags, struct inode *inode, unsigned seq) 17203ddcd056SLinus Torvalds { 172131d66bcdSAl Viro if (!(flags & WALK_MORE) && nd->depth) 172231d66bcdSAl Viro put_link(nd); 17238f64fb1cSAl Viro if (likely(!d_is_symlink(path->dentry)) || 17248f64fb1cSAl Viro !(flags & WALK_FOLLOW || nd->flags & LOOKUP_FOLLOW)) { 17258f64fb1cSAl Viro /* not a symlink or should not follow */ 17268f64fb1cSAl Viro path_to_nameidata(path, nd); 17278f64fb1cSAl Viro nd->inode = inode; 17288f64fb1cSAl Viro nd->seq = seq; 1729d63ff28fSAl Viro return 0; 17308f64fb1cSAl Viro } 1731a7f77542SAl Viro /* make sure that d_is_symlink above matches inode */ 1732a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 17338f64fb1cSAl Viro if (read_seqcount_retry(&path->dentry->d_seq, seq)) 1734a7f77542SAl Viro return -ECHILD; 1735a7f77542SAl Viro } 17368f64fb1cSAl Viro return pick_link(nd, path, inode, seq); 17373ddcd056SLinus Torvalds } 17383ddcd056SLinus Torvalds 17394693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1740ce57dfc1SAl Viro { 1741caa85634SAl Viro struct path path; 1742ce57dfc1SAl Viro struct inode *inode; 1743254cf582SAl Viro unsigned seq; 1744ce57dfc1SAl Viro int err; 1745ce57dfc1SAl Viro /* 1746ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1747ce57dfc1SAl Viro * to be able to know about the current root directory and 1748ce57dfc1SAl Viro * parent relationships. 1749ce57dfc1SAl Viro */ 17504693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 17514693a547SAl Viro err = handle_dots(nd, nd->last_type); 17521c4ff1a8SAl Viro if (!(flags & WALK_MORE) && nd->depth) 17534693a547SAl Viro put_link(nd); 17544693a547SAl Viro return err; 17554693a547SAl Viro } 1756254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1757e9742b53SAl Viro if (unlikely(err <= 0)) { 1758697f514dSMiklos Szeredi if (err < 0) 1759f0a9ba70SAl Viro return err; 1760e3c13928SAl Viro path.dentry = lookup_slow(&nd->last, nd->path.dentry, 1761e3c13928SAl Viro nd->flags); 1762e3c13928SAl Viro if (IS_ERR(path.dentry)) 1763e3c13928SAl Viro return PTR_ERR(path.dentry); 17647500c38aSAl Viro 1765e3c13928SAl Viro path.mnt = nd->path.mnt; 1766e3c13928SAl Viro err = follow_managed(&path, nd); 1767e3c13928SAl Viro if (unlikely(err < 0)) 1768f0a9ba70SAl Viro return err; 1769697f514dSMiklos Szeredi 17707500c38aSAl Viro if (unlikely(d_is_negative(path.dentry))) { 17717500c38aSAl Viro path_to_nameidata(&path, nd); 17727500c38aSAl Viro return -ENOENT; 17737500c38aSAl Viro } 17747500c38aSAl Viro 1775254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1776d4565649SAl Viro inode = d_backing_inode(path.dentry); 1777766c4cbfSAl Viro } 1778697f514dSMiklos Szeredi 17798f64fb1cSAl Viro return step_into(nd, &path, flags, inode, seq); 1780ce57dfc1SAl Viro } 1781ce57dfc1SAl Viro 17821da177e4SLinus Torvalds /* 1783bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1784bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1785bfcfaa77SLinus Torvalds * 1786bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1787bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1788bfcfaa77SLinus Torvalds * fast. 1789bfcfaa77SLinus Torvalds * 1790bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1791bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1792bfcfaa77SLinus Torvalds * crossing operation. 1793bfcfaa77SLinus Torvalds * 1794bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1795bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1796bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1797bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1798bfcfaa77SLinus Torvalds */ 1799bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1800bfcfaa77SLinus Torvalds 1801f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1802bfcfaa77SLinus Torvalds 1803468a9428SGeorge Spelvin #ifdef HASH_MIX 1804bfcfaa77SLinus Torvalds 1805468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1806468a9428SGeorge Spelvin 1807468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 18082a18da7aSGeorge Spelvin /* 18092a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 18102a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 18112a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 18122a18da7aSGeorge Spelvin * and no temporaries. 18132a18da7aSGeorge Spelvin * 18142a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 18152a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 18162a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 18172a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 18182a18da7aSGeorge Spelvin * 18192a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 18202a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 18212a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 18222a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 18232a18da7aSGeorge Spelvin * 18242a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 18252a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 18262a18da7aSGeorge Spelvin * toggling any given output bit. 18272a18da7aSGeorge Spelvin * 18282a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 18292a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18302a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 18312a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 18322a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 18332a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 18342a18da7aSGeorge Spelvin * Perfect: 8192 258048 18352a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 18362a18da7aSGeorge Spelvin */ 18372a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18382a18da7aSGeorge Spelvin ( x ^= (a), \ 18392a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 18402a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 18412a18da7aSGeorge Spelvin y *= 9 ) 1842bfcfaa77SLinus Torvalds 18430fed3ac8SGeorge Spelvin /* 18442a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 18452a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 18462a18da7aSGeorge Spelvin * work done before the hash value is used. 18470fed3ac8SGeorge Spelvin */ 18482a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18490fed3ac8SGeorge Spelvin { 18502a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 18512a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 18522a18da7aSGeorge Spelvin return y >> 32; 18530fed3ac8SGeorge Spelvin } 18540fed3ac8SGeorge Spelvin 1855bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1856bfcfaa77SLinus Torvalds 18572a18da7aSGeorge Spelvin /* 18582a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 18592a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18602a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 18612a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 18622a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 18632a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 18642a18da7aSGeorge Spelvin * Perfect: 2048 31744 18652a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 18662a18da7aSGeorge Spelvin */ 18672a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18682a18da7aSGeorge Spelvin ( x ^= (a), \ 18692a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 18702a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 18712a18da7aSGeorge Spelvin y *= 9 ) 1872bfcfaa77SLinus Torvalds 18732a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18740fed3ac8SGeorge Spelvin { 18752a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 18762a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 18770fed3ac8SGeorge Spelvin } 18780fed3ac8SGeorge Spelvin 1879bfcfaa77SLinus Torvalds #endif 1880bfcfaa77SLinus Torvalds 18812a18da7aSGeorge Spelvin /* 18822a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 18832a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 18842a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 18852a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 18862a18da7aSGeorge Spelvin * finds the delimiter after the name. 18872a18da7aSGeorge Spelvin */ 18888387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 1889bfcfaa77SLinus Torvalds { 18908387ff25SLinus Torvalds unsigned long a, x = 0, y = (unsigned long)salt; 1891bfcfaa77SLinus Torvalds 1892bfcfaa77SLinus Torvalds for (;;) { 1893fcfd2fbfSGeorge Spelvin if (!len) 1894fcfd2fbfSGeorge Spelvin goto done; 1895e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1896bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1897bfcfaa77SLinus Torvalds break; 18982a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1899bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1900bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1901bfcfaa77SLinus Torvalds } 19022a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 1903bfcfaa77SLinus Torvalds done: 19042a18da7aSGeorge Spelvin return fold_hash(x, y); 1905bfcfaa77SLinus Torvalds } 1906bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1907bfcfaa77SLinus Torvalds 1908fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 19098387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 1910fcfd2fbfSGeorge Spelvin { 19118387ff25SLinus Torvalds unsigned long a = 0, x = 0, y = (unsigned long)salt; 19128387ff25SLinus Torvalds unsigned long adata, mask, len; 1913fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1914fcfd2fbfSGeorge Spelvin 19158387ff25SLinus Torvalds len = 0; 19168387ff25SLinus Torvalds goto inside; 19178387ff25SLinus Torvalds 1918fcfd2fbfSGeorge Spelvin do { 19192a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1920fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 19218387ff25SLinus Torvalds inside: 1922fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 1923fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 1924fcfd2fbfSGeorge Spelvin 1925fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 1926fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 19272a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 1928fcfd2fbfSGeorge Spelvin 19292a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1930fcfd2fbfSGeorge Spelvin } 1931fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 1932fcfd2fbfSGeorge Spelvin 1933bfcfaa77SLinus Torvalds /* 1934bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1935d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1936bfcfaa77SLinus Torvalds */ 19378387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 1938bfcfaa77SLinus Torvalds { 19398387ff25SLinus Torvalds unsigned long a = 0, b, x = 0, y = (unsigned long)salt; 19408387ff25SLinus Torvalds unsigned long adata, bdata, mask, len; 194136126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1942bfcfaa77SLinus Torvalds 19438387ff25SLinus Torvalds len = 0; 19448387ff25SLinus Torvalds goto inside; 19458387ff25SLinus Torvalds 1946bfcfaa77SLinus Torvalds do { 19472a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1948bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 19498387ff25SLinus Torvalds inside: 1950e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 195136126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 195236126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1953bfcfaa77SLinus Torvalds 195436126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 195536126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 195636126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 19572a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 195836126f8fSLinus Torvalds 19592a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1960bfcfaa77SLinus Torvalds } 1961bfcfaa77SLinus Torvalds 19622a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 1963bfcfaa77SLinus Torvalds 1964fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 19658387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 19660145acc2SLinus Torvalds { 19678387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 19680145acc2SLinus Torvalds while (len--) 1969fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 19700145acc2SLinus Torvalds return end_name_hash(hash); 19710145acc2SLinus Torvalds } 1972ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 19730145acc2SLinus Torvalds 1974fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 19758387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 1976fcfd2fbfSGeorge Spelvin { 19778387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 1978fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 1979fcfd2fbfSGeorge Spelvin 1980fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 1981e0ab7af9SGeorge Spelvin while (c) { 1982fcfd2fbfSGeorge Spelvin len++; 1983fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 1984fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 1985e0ab7af9SGeorge Spelvin } 1986fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 1987fcfd2fbfSGeorge Spelvin } 1988f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 1989fcfd2fbfSGeorge Spelvin 19903ddcd056SLinus Torvalds /* 1991200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1992200e9ef7SLinus Torvalds * one character. 1993200e9ef7SLinus Torvalds */ 19948387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 1995200e9ef7SLinus Torvalds { 19968387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 1997200e9ef7SLinus Torvalds unsigned long len = 0, c; 1998200e9ef7SLinus Torvalds 1999200e9ef7SLinus Torvalds c = (unsigned char)*name; 2000200e9ef7SLinus Torvalds do { 2001200e9ef7SLinus Torvalds len++; 2002200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2003200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2004200e9ef7SLinus Torvalds } while (c && c != '/'); 2005d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2006200e9ef7SLinus Torvalds } 2007200e9ef7SLinus Torvalds 2008bfcfaa77SLinus Torvalds #endif 2009bfcfaa77SLinus Torvalds 2010200e9ef7SLinus Torvalds /* 20111da177e4SLinus Torvalds * Name resolution. 2012ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2013ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 20141da177e4SLinus Torvalds * 2015ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2016ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 20171da177e4SLinus Torvalds */ 20186de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 20191da177e4SLinus Torvalds { 20201da177e4SLinus Torvalds int err; 20211da177e4SLinus Torvalds 20221da177e4SLinus Torvalds while (*name=='/') 20231da177e4SLinus Torvalds name++; 20241da177e4SLinus Torvalds if (!*name) 20259e18f10aSAl Viro return 0; 20261da177e4SLinus Torvalds 20271da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 20281da177e4SLinus Torvalds for(;;) { 2029d6bb3e90SLinus Torvalds u64 hash_len; 2030fe479a58SAl Viro int type; 20311da177e4SLinus Torvalds 203252094c8aSAl Viro err = may_lookup(nd); 20331da177e4SLinus Torvalds if (err) 20343595e234SAl Viro return err; 20351da177e4SLinus Torvalds 20368387ff25SLinus Torvalds hash_len = hash_name(nd->path.dentry, name); 20371da177e4SLinus Torvalds 2038fe479a58SAl Viro type = LAST_NORM; 2039d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2040fe479a58SAl Viro case 2: 2041200e9ef7SLinus Torvalds if (name[1] == '.') { 2042fe479a58SAl Viro type = LAST_DOTDOT; 204316c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 204416c2cd71SAl Viro } 2045fe479a58SAl Viro break; 2046fe479a58SAl Viro case 1: 2047fe479a58SAl Viro type = LAST_DOT; 2048fe479a58SAl Viro } 20495a202bcdSAl Viro if (likely(type == LAST_NORM)) { 20505a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 205116c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 20525a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2053a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2054da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 20555a202bcdSAl Viro if (err < 0) 20563595e234SAl Viro return err; 2057d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2058d6bb3e90SLinus Torvalds name = this.name; 20595a202bcdSAl Viro } 20605a202bcdSAl Viro } 2061fe479a58SAl Viro 2062d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2063d6bb3e90SLinus Torvalds nd->last.name = name; 20645f4a6a69SAl Viro nd->last_type = type; 20655f4a6a69SAl Viro 2066d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2067d6bb3e90SLinus Torvalds if (!*name) 2068bdf6cbf1SAl Viro goto OK; 2069200e9ef7SLinus Torvalds /* 2070200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2071200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2072200e9ef7SLinus Torvalds */ 2073200e9ef7SLinus Torvalds do { 2074d6bb3e90SLinus Torvalds name++; 2075d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 20768620c238SAl Viro if (unlikely(!*name)) { 20778620c238SAl Viro OK: 2078368ee9baSAl Viro /* pathname body, done */ 20798620c238SAl Viro if (!nd->depth) 20808620c238SAl Viro return 0; 20818620c238SAl Viro name = nd->stack[nd->depth - 1].name; 2082368ee9baSAl Viro /* trailing symlink, done */ 20838620c238SAl Viro if (!name) 20848620c238SAl Viro return 0; 20858620c238SAl Viro /* last component of nested symlink */ 20868f64fb1cSAl Viro err = walk_component(nd, WALK_FOLLOW); 20871c4ff1a8SAl Viro } else { 20881c4ff1a8SAl Viro /* not the last component */ 20898f64fb1cSAl Viro err = walk_component(nd, WALK_FOLLOW | WALK_MORE); 20908620c238SAl Viro } 2091ce57dfc1SAl Viro if (err < 0) 20923595e234SAl Viro return err; 2093fe479a58SAl Viro 2094ce57dfc1SAl Viro if (err) { 2095626de996SAl Viro const char *s = get_link(nd); 20965a460275SAl Viro 2097a1c83681SViresh Kumar if (IS_ERR(s)) 20983595e234SAl Viro return PTR_ERR(s); 2099172a39a0SAl Viro err = 0; 210012b09578SAl Viro if (unlikely(!s)) { 210112b09578SAl Viro /* jumped */ 2102b9ff4429SAl Viro put_link(nd); 210312b09578SAl Viro } else { 2104071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 210532cd7468SAl Viro name = s; 21069e18f10aSAl Viro continue; 210748c8b0c5SAl Viro } 210831e6b01fSNick Piggin } 210997242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 211097242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 211197242f99SAl Viro if (unlazy_walk(nd, NULL, 0)) 211297242f99SAl Viro return -ECHILD; 211397242f99SAl Viro } 21143595e234SAl Viro return -ENOTDIR; 21155f4a6a69SAl Viro } 2116ce57dfc1SAl Viro } 211797242f99SAl Viro } 21181da177e4SLinus Torvalds 2119c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 212031e6b01fSNick Piggin { 212131e6b01fSNick Piggin int retval = 0; 2122c8a53ee5SAl Viro const char *s = nd->name->name; 212331e6b01fSNick Piggin 212431e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 2125980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 212631e6b01fSNick Piggin nd->depth = 0; 21275b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2128b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2129b18825a7SDavid Howells struct inode *inode = root->d_inode; 2130fd2f7cb5SAl Viro if (*s) { 213144b1d530SMiklos Szeredi if (!d_can_lookup(root)) 2132368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 21335b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 21345b6ca027SAl Viro if (retval) 2135368ee9baSAl Viro return ERR_PTR(retval); 213673d049a4SAl Viro } 21375b6ca027SAl Viro nd->path = nd->root; 21385b6ca027SAl Viro nd->inode = inode; 21395b6ca027SAl Viro if (flags & LOOKUP_RCU) { 21408b61e74fSAl Viro rcu_read_lock(); 21415b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 21428f47a016SAl Viro nd->root_seq = nd->seq; 214348a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 21445b6ca027SAl Viro } else { 21455b6ca027SAl Viro path_get(&nd->path); 21465b6ca027SAl Viro } 2147368ee9baSAl Viro return s; 21485b6ca027SAl Viro } 21495b6ca027SAl Viro 215031e6b01fSNick Piggin nd->root.mnt = NULL; 2151248fb5b9SAl Viro nd->path.mnt = NULL; 2152248fb5b9SAl Viro nd->path.dentry = NULL; 215331e6b01fSNick Piggin 215448a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 2155fd2f7cb5SAl Viro if (*s == '/') { 21569e6697e2SAl Viro if (flags & LOOKUP_RCU) 21578b61e74fSAl Viro rcu_read_lock(); 2158e41f7d4eSAl Viro set_root(nd); 2159248fb5b9SAl Viro if (likely(!nd_jump_root(nd))) 2160ef55d917SAl Viro return s; 2161ef55d917SAl Viro nd->root.mnt = NULL; 2162ef55d917SAl Viro rcu_read_unlock(); 2163ef55d917SAl Viro return ERR_PTR(-ECHILD); 2164c8a53ee5SAl Viro } else if (nd->dfd == AT_FDCWD) { 2165e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 216631e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2167c28cc364SNick Piggin unsigned seq; 216831e6b01fSNick Piggin 21698b61e74fSAl Viro rcu_read_lock(); 217031e6b01fSNick Piggin 2171c28cc364SNick Piggin do { 2172c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 217331e6b01fSNick Piggin nd->path = fs->pwd; 2174ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2175c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2176c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2177e41f7d4eSAl Viro } else { 2178e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2179ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2180e41f7d4eSAl Viro } 2181ef55d917SAl Viro return s; 218231e6b01fSNick Piggin } else { 2183582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2184c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 218531e6b01fSNick Piggin struct dentry *dentry; 218631e6b01fSNick Piggin 21872903ff01SAl Viro if (!f.file) 2188368ee9baSAl Viro return ERR_PTR(-EBADF); 218931e6b01fSNick Piggin 21902903ff01SAl Viro dentry = f.file->f_path.dentry; 219131e6b01fSNick Piggin 2192fd2f7cb5SAl Viro if (*s) { 219344b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 21942903ff01SAl Viro fdput(f); 2195368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2196f52e0c11SAl Viro } 21972903ff01SAl Viro } 21982903ff01SAl Viro 21992903ff01SAl Viro nd->path = f.file->f_path; 2200e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 22018b61e74fSAl Viro rcu_read_lock(); 220234a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 220334a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22045590ff0dSUlrich Drepper } else { 22052903ff01SAl Viro path_get(&nd->path); 220634a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 22071da177e4SLinus Torvalds } 220834a26b99SAl Viro fdput(f); 2209368ee9baSAl Viro return s; 2210e41f7d4eSAl Viro } 22119b4a9b14SAl Viro } 22129b4a9b14SAl Viro 22133bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 221495fa25d9SAl Viro { 221595fa25d9SAl Viro const char *s; 2216fec2fa24SAl Viro int error = may_follow_link(nd); 2217deb106c6SAl Viro if (unlikely(error)) 22183bdba28bSAl Viro return ERR_PTR(error); 221995fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2220fab51e8aSAl Viro nd->stack[0].name = NULL; 22213b2e7f75SAl Viro s = get_link(nd); 2222deb106c6SAl Viro return s ? s : ""; 222395fa25d9SAl Viro } 222495fa25d9SAl Viro 2225caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2226bd92d7feSAl Viro { 2227bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2228bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2229bd92d7feSAl Viro 2230bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 22311c4ff1a8SAl Viro return walk_component(nd, 0); 2232bd92d7feSAl Viro } 2233bd92d7feSAl Viro 22349b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2235c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 22369b4a9b14SAl Viro { 2237c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2238bd92d7feSAl Viro int err; 223931e6b01fSNick Piggin 2240368ee9baSAl Viro if (IS_ERR(s)) 2241368ee9baSAl Viro return PTR_ERR(s); 22423bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 22433bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 22443bdba28bSAl Viro s = trailing_symlink(nd); 22453bdba28bSAl Viro if (IS_ERR(s)) { 22463bdba28bSAl Viro err = PTR_ERR(s); 22476d7b5aaeSAl Viro break; 2248bd92d7feSAl Viro } 2249bd92d7feSAl Viro } 22509f1fafeeSAl Viro if (!err) 22519f1fafeeSAl Viro err = complete_walk(nd); 2252bd92d7feSAl Viro 2253deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2254deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2255bd23a539SAl Viro err = -ENOTDIR; 2256625b6d10SAl Viro if (!err) { 2257625b6d10SAl Viro *path = nd->path; 2258625b6d10SAl Viro nd->path.mnt = NULL; 2259625b6d10SAl Viro nd->path.dentry = NULL; 2260625b6d10SAl Viro } 2261deb106c6SAl Viro terminate_walk(nd); 2262bd92d7feSAl Viro return err; 226331e6b01fSNick Piggin } 226431e6b01fSNick Piggin 2265625b6d10SAl Viro static int filename_lookup(int dfd, struct filename *name, unsigned flags, 22669ad1aaa6SAl Viro struct path *path, struct path *root) 2267873f1eedSJeff Layton { 2268894bc8c4SAl Viro int retval; 22699883d185SAl Viro struct nameidata nd; 2270abc9f5beSAl Viro if (IS_ERR(name)) 2271abc9f5beSAl Viro return PTR_ERR(name); 22729ad1aaa6SAl Viro if (unlikely(root)) { 22739ad1aaa6SAl Viro nd.root = *root; 22749ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 22759ad1aaa6SAl Viro } 22769883d185SAl Viro set_nameidata(&nd, dfd, name); 2277c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2278873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2279c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2280873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2281c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2282873f1eedSJeff Layton 2283873f1eedSJeff Layton if (likely(!retval)) 2284625b6d10SAl Viro audit_inode(name, path->dentry, flags & LOOKUP_PARENT); 22859883d185SAl Viro restore_nameidata(); 2286e4bd1c1aSAl Viro putname(name); 2287873f1eedSJeff Layton return retval; 2288873f1eedSJeff Layton } 2289873f1eedSJeff Layton 22908bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2291c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2292391172c4SAl Viro struct path *parent) 22938bcb77faSAl Viro { 2294c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2295368ee9baSAl Viro int err; 2296368ee9baSAl Viro if (IS_ERR(s)) 2297368ee9baSAl Viro return PTR_ERR(s); 2298368ee9baSAl Viro err = link_path_walk(s, nd); 22998bcb77faSAl Viro if (!err) 23008bcb77faSAl Viro err = complete_walk(nd); 2301391172c4SAl Viro if (!err) { 2302391172c4SAl Viro *parent = nd->path; 2303391172c4SAl Viro nd->path.mnt = NULL; 2304391172c4SAl Viro nd->path.dentry = NULL; 2305391172c4SAl Viro } 2306deb106c6SAl Viro terminate_walk(nd); 23078bcb77faSAl Viro return err; 23088bcb77faSAl Viro } 23098bcb77faSAl Viro 23105c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2311391172c4SAl Viro unsigned int flags, struct path *parent, 2312391172c4SAl Viro struct qstr *last, int *type) 23138bcb77faSAl Viro { 23148bcb77faSAl Viro int retval; 23159883d185SAl Viro struct nameidata nd; 23168bcb77faSAl Viro 23175c31b6ceSAl Viro if (IS_ERR(name)) 23185c31b6ceSAl Viro return name; 23199883d185SAl Viro set_nameidata(&nd, dfd, name); 2320c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 23218bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2322c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 23238bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2324c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2325391172c4SAl Viro if (likely(!retval)) { 2326391172c4SAl Viro *last = nd.last; 2327391172c4SAl Viro *type = nd.last_type; 2328391172c4SAl Viro audit_inode(name, parent->dentry, LOOKUP_PARENT); 23295c31b6ceSAl Viro } else { 23305c31b6ceSAl Viro putname(name); 23315c31b6ceSAl Viro name = ERR_PTR(retval); 2332391172c4SAl Viro } 23339883d185SAl Viro restore_nameidata(); 23345c31b6ceSAl Viro return name; 23358bcb77faSAl Viro } 23368bcb77faSAl Viro 233779714f72SAl Viro /* does lookup, returns the object with parent locked */ 233879714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 23395590ff0dSUlrich Drepper { 23405c31b6ceSAl Viro struct filename *filename; 23415c31b6ceSAl Viro struct dentry *d; 2342391172c4SAl Viro struct qstr last; 2343391172c4SAl Viro int type; 234451689104SPaul Moore 23455c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 23465c31b6ceSAl Viro &last, &type); 234751689104SPaul Moore if (IS_ERR(filename)) 234851689104SPaul Moore return ERR_CAST(filename); 23495c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2350391172c4SAl Viro path_put(path); 23515c31b6ceSAl Viro putname(filename); 23525c31b6ceSAl Viro return ERR_PTR(-EINVAL); 235379714f72SAl Viro } 23545955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2355391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 235679714f72SAl Viro if (IS_ERR(d)) { 23575955102cSAl Viro inode_unlock(path->dentry->d_inode); 2358391172c4SAl Viro path_put(path); 235979714f72SAl Viro } 236051689104SPaul Moore putname(filename); 236179714f72SAl Viro return d; 23625590ff0dSUlrich Drepper } 23635590ff0dSUlrich Drepper 2364d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2365d1811465SAl Viro { 2366abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2367abc9f5beSAl Viro flags, path, NULL); 2368d1811465SAl Viro } 23694d359507SAl Viro EXPORT_SYMBOL(kern_path); 2370d1811465SAl Viro 237116f18200SJosef 'Jeff' Sipek /** 237216f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 237316f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 237416f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 237516f18200SJosef 'Jeff' Sipek * @name: pointer to file name 237616f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2377e0a01249SAl Viro * @path: pointer to struct path to fill 237816f18200SJosef 'Jeff' Sipek */ 237916f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 238016f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2381e0a01249SAl Viro struct path *path) 238216f18200SJosef 'Jeff' Sipek { 23839ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 23849ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2385abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2386abc9f5beSAl Viro flags , path, &root); 238716f18200SJosef 'Jeff' Sipek } 23884d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 238916f18200SJosef 'Jeff' Sipek 2390eead1911SChristoph Hellwig /** 2391a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2392eead1911SChristoph Hellwig * @name: pathname component to lookup 2393eead1911SChristoph Hellwig * @base: base directory to lookup from 2394eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2395eead1911SChristoph Hellwig * 2396a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 23979e7543e9SAl Viro * not be called by generic code. 2398bbddca8eSNeilBrown * 2399bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2400eead1911SChristoph Hellwig */ 2401057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2402057f6c01SJames Morris { 2403057f6c01SJames Morris struct qstr this; 24046a96ba54SAl Viro unsigned int c; 2405cda309deSMiklos Szeredi int err; 2406057f6c01SJames Morris 24075955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 24082f9092e1SDavid Woodhouse 24096a96ba54SAl Viro this.name = name; 24106a96ba54SAl Viro this.len = len; 24118387ff25SLinus Torvalds this.hash = full_name_hash(base, name, len); 24126a96ba54SAl Viro if (!len) 24136a96ba54SAl Viro return ERR_PTR(-EACCES); 24146a96ba54SAl Viro 241521d8a15aSAl Viro if (unlikely(name[0] == '.')) { 241621d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 241721d8a15aSAl Viro return ERR_PTR(-EACCES); 241821d8a15aSAl Viro } 241921d8a15aSAl Viro 24206a96ba54SAl Viro while (len--) { 24216a96ba54SAl Viro c = *(const unsigned char *)name++; 24226a96ba54SAl Viro if (c == '/' || c == '\0') 24236a96ba54SAl Viro return ERR_PTR(-EACCES); 24246a96ba54SAl Viro } 24255a202bcdSAl Viro /* 24265a202bcdSAl Viro * See if the low-level filesystem might want 24275a202bcdSAl Viro * to use its own hash.. 24285a202bcdSAl Viro */ 24295a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2430da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 24315a202bcdSAl Viro if (err < 0) 24325a202bcdSAl Viro return ERR_PTR(err); 24335a202bcdSAl Viro } 2434eead1911SChristoph Hellwig 2435cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2436cda309deSMiklos Szeredi if (err) 2437cda309deSMiklos Szeredi return ERR_PTR(err); 2438cda309deSMiklos Szeredi 243972bd866aSAl Viro return __lookup_hash(&this, base, 0); 2440057f6c01SJames Morris } 24414d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2442057f6c01SJames Morris 2443bbddca8eSNeilBrown /** 2444bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2445bbddca8eSNeilBrown * @name: pathname component to lookup 2446bbddca8eSNeilBrown * @base: base directory to lookup from 2447bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2448bbddca8eSNeilBrown * 2449bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2450bbddca8eSNeilBrown * not be called by generic code. 2451bbddca8eSNeilBrown * 2452bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2453bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2454bbddca8eSNeilBrown */ 2455bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2456bbddca8eSNeilBrown struct dentry *base, int len) 2457bbddca8eSNeilBrown { 2458bbddca8eSNeilBrown struct qstr this; 2459bbddca8eSNeilBrown unsigned int c; 2460bbddca8eSNeilBrown int err; 246120d00ee8SLinus Torvalds struct dentry *ret; 2462bbddca8eSNeilBrown 2463bbddca8eSNeilBrown this.name = name; 2464bbddca8eSNeilBrown this.len = len; 24658387ff25SLinus Torvalds this.hash = full_name_hash(base, name, len); 2466bbddca8eSNeilBrown if (!len) 2467bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2468bbddca8eSNeilBrown 2469bbddca8eSNeilBrown if (unlikely(name[0] == '.')) { 2470bbddca8eSNeilBrown if (len < 2 || (len == 2 && name[1] == '.')) 2471bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2472bbddca8eSNeilBrown } 2473bbddca8eSNeilBrown 2474bbddca8eSNeilBrown while (len--) { 2475bbddca8eSNeilBrown c = *(const unsigned char *)name++; 2476bbddca8eSNeilBrown if (c == '/' || c == '\0') 2477bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2478bbddca8eSNeilBrown } 2479bbddca8eSNeilBrown /* 2480bbddca8eSNeilBrown * See if the low-level filesystem might want 2481bbddca8eSNeilBrown * to use its own hash.. 2482bbddca8eSNeilBrown */ 2483bbddca8eSNeilBrown if (base->d_flags & DCACHE_OP_HASH) { 2484bbddca8eSNeilBrown int err = base->d_op->d_hash(base, &this); 2485bbddca8eSNeilBrown if (err < 0) 2486bbddca8eSNeilBrown return ERR_PTR(err); 2487bbddca8eSNeilBrown } 2488bbddca8eSNeilBrown 2489bbddca8eSNeilBrown err = inode_permission(base->d_inode, MAY_EXEC); 2490bbddca8eSNeilBrown if (err) 2491bbddca8eSNeilBrown return ERR_PTR(err); 2492bbddca8eSNeilBrown 249320d00ee8SLinus Torvalds ret = lookup_dcache(&this, base, 0); 249420d00ee8SLinus Torvalds if (!ret) 249520d00ee8SLinus Torvalds ret = lookup_slow(&this, base, 0); 249620d00ee8SLinus Torvalds return ret; 2497bbddca8eSNeilBrown } 2498bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2499bbddca8eSNeilBrown 2500eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2501eedf265aSEric W. Biederman int path_pts(struct path *path) 2502eedf265aSEric W. Biederman { 2503eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2504eedf265aSEric W. Biederman * the input path. 2505eedf265aSEric W. Biederman */ 2506eedf265aSEric W. Biederman struct dentry *child, *parent; 2507eedf265aSEric W. Biederman struct qstr this; 2508eedf265aSEric W. Biederman int ret; 2509eedf265aSEric W. Biederman 2510eedf265aSEric W. Biederman ret = path_parent_directory(path); 2511eedf265aSEric W. Biederman if (ret) 2512eedf265aSEric W. Biederman return ret; 2513eedf265aSEric W. Biederman 2514eedf265aSEric W. Biederman parent = path->dentry; 2515eedf265aSEric W. Biederman this.name = "pts"; 2516eedf265aSEric W. Biederman this.len = 3; 2517eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2518eedf265aSEric W. Biederman if (!child) 2519eedf265aSEric W. Biederman return -ENOENT; 2520eedf265aSEric W. Biederman 2521eedf265aSEric W. Biederman path->dentry = child; 2522eedf265aSEric W. Biederman dput(parent); 2523eedf265aSEric W. Biederman follow_mount(path); 2524eedf265aSEric W. Biederman return 0; 2525eedf265aSEric W. Biederman } 2526eedf265aSEric W. Biederman #endif 2527eedf265aSEric W. Biederman 25281fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 25291fa1e7f6SAndy Whitcroft struct path *path, int *empty) 25301da177e4SLinus Torvalds { 2531abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2532abc9f5beSAl Viro flags, path, NULL); 25331da177e4SLinus Torvalds } 2534b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 25351fa1e7f6SAndy Whitcroft 25368033426eSJeff Layton /** 2537197df04cSAl Viro * mountpoint_last - look up last component for umount 25388033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 25398033426eSJeff Layton * 25408033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 25418033426eSJeff Layton * need to resolve the path without doing any revalidation. 25428033426eSJeff Layton * 25438033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 25448033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 25458033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 25468033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 25478033426eSJeff Layton * bogus and it doesn't exist. 25488033426eSJeff Layton * 25498033426eSJeff Layton * Returns: 25508033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 2551ba8f4613SAl Viro * lookup found a negative dentry. 25528033426eSJeff Layton * 2553ba8f4613SAl Viro * 0: if we successfully resolved nd->last and found it to not to be a 2554ba8f4613SAl Viro * symlink that needs to be followed. 25558033426eSJeff Layton * 25568033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 2557ba8f4613SAl Viro * that needs to be followed. 25588033426eSJeff Layton */ 25598033426eSJeff Layton static int 2560ba8f4613SAl Viro mountpoint_last(struct nameidata *nd) 25618033426eSJeff Layton { 25628033426eSJeff Layton int error = 0; 25638033426eSJeff Layton struct dentry *dir = nd->path.dentry; 2564ba8f4613SAl Viro struct path path; 25658033426eSJeff Layton 256635759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 256735759521SAl Viro if (nd->flags & LOOKUP_RCU) { 25686e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 2569deb106c6SAl Viro return -ECHILD; 25708033426eSJeff Layton } 25718033426eSJeff Layton 25728033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 25738033426eSJeff Layton 25748033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 25758033426eSJeff Layton error = handle_dots(nd, nd->last_type); 257635759521SAl Viro if (error) 2577deb106c6SAl Viro return error; 2578ba8f4613SAl Viro path.dentry = dget(nd->path.dentry); 2579949a852eSAl Viro } else { 2580ba8f4613SAl Viro path.dentry = d_lookup(dir, &nd->last); 2581ba8f4613SAl Viro if (!path.dentry) { 25828033426eSJeff Layton /* 2583949a852eSAl Viro * No cached dentry. Mounted dentries are pinned in the 2584949a852eSAl Viro * cache, so that means that this dentry is probably 2585949a852eSAl Viro * a symlink or the path doesn't actually point 2586949a852eSAl Viro * to a mounted dentry. 25878033426eSJeff Layton */ 2588ba8f4613SAl Viro path.dentry = lookup_slow(&nd->last, dir, 2589949a852eSAl Viro nd->flags | LOOKUP_NO_REVAL); 2590ba8f4613SAl Viro if (IS_ERR(path.dentry)) 2591ba8f4613SAl Viro return PTR_ERR(path.dentry); 25928033426eSJeff Layton } 2593bcceeebaSDave Jones } 2594ba8f4613SAl Viro if (d_is_negative(path.dentry)) { 2595ba8f4613SAl Viro dput(path.dentry); 2596deb106c6SAl Viro return -ENOENT; 259735759521SAl Viro } 2598ba8f4613SAl Viro path.mnt = nd->path.mnt; 25998f64fb1cSAl Viro return step_into(nd, &path, 0, d_backing_inode(path.dentry), 0); 26008033426eSJeff Layton } 26018033426eSJeff Layton 26028033426eSJeff Layton /** 2603197df04cSAl Viro * path_mountpoint - look up a path to be umounted 26042a78b857SMasanari Iida * @nd: lookup context 26058033426eSJeff Layton * @flags: lookup flags 2606c8a53ee5SAl Viro * @path: pointer to container for result 26078033426eSJeff Layton * 26088033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2609606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 26108033426eSJeff Layton */ 26118033426eSJeff Layton static int 2612c8a53ee5SAl Viro path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) 26138033426eSJeff Layton { 2614c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2615368ee9baSAl Viro int err; 2616368ee9baSAl Viro if (IS_ERR(s)) 2617368ee9baSAl Viro return PTR_ERR(s); 26183bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 2619ba8f4613SAl Viro (err = mountpoint_last(nd)) > 0) { 26203bdba28bSAl Viro s = trailing_symlink(nd); 26213bdba28bSAl Viro if (IS_ERR(s)) { 26223bdba28bSAl Viro err = PTR_ERR(s); 26238033426eSJeff Layton break; 26248033426eSJeff Layton } 26253bdba28bSAl Viro } 2626ba8f4613SAl Viro if (!err) { 2627ba8f4613SAl Viro *path = nd->path; 2628ba8f4613SAl Viro nd->path.mnt = NULL; 2629ba8f4613SAl Viro nd->path.dentry = NULL; 2630ba8f4613SAl Viro follow_mount(path); 2631ba8f4613SAl Viro } 2632deb106c6SAl Viro terminate_walk(nd); 26338033426eSJeff Layton return err; 26348033426eSJeff Layton } 26358033426eSJeff Layton 26362d864651SAl Viro static int 2637668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 26382d864651SAl Viro unsigned int flags) 26392d864651SAl Viro { 26409883d185SAl Viro struct nameidata nd; 2641cbaab2dbSAl Viro int error; 2642668696dcSAl Viro if (IS_ERR(name)) 2643668696dcSAl Viro return PTR_ERR(name); 26449883d185SAl Viro set_nameidata(&nd, dfd, name); 2645c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); 26462d864651SAl Viro if (unlikely(error == -ECHILD)) 2647c8a53ee5SAl Viro error = path_mountpoint(&nd, flags, path); 26482d864651SAl Viro if (unlikely(error == -ESTALE)) 2649c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); 26502d864651SAl Viro if (likely(!error)) 2651668696dcSAl Viro audit_inode(name, path->dentry, 0); 26529883d185SAl Viro restore_nameidata(); 2653668696dcSAl Viro putname(name); 26542d864651SAl Viro return error; 26552d864651SAl Viro } 26562d864651SAl Viro 26578033426eSJeff Layton /** 2658197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 26598033426eSJeff Layton * @dfd: directory file descriptor 26608033426eSJeff Layton * @name: pathname from userland 26618033426eSJeff Layton * @flags: lookup flags 26628033426eSJeff Layton * @path: pointer to container to hold result 26638033426eSJeff Layton * 26648033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 26658033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 26668033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 26678033426eSJeff Layton * and avoid revalidating the last component. 26688033426eSJeff Layton * 26698033426eSJeff Layton * Returns 0 and populates "path" on success. 26708033426eSJeff Layton */ 26718033426eSJeff Layton int 2672197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 26738033426eSJeff Layton struct path *path) 26748033426eSJeff Layton { 2675cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 26768033426eSJeff Layton } 26778033426eSJeff Layton 26782d864651SAl Viro int 26792d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 26802d864651SAl Viro unsigned int flags) 26812d864651SAl Viro { 2682cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 26832d864651SAl Viro } 26842d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 26852d864651SAl Viro 2686cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 26871da177e4SLinus Torvalds { 26888e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2689da9592edSDavid Howells 26908e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 26911da177e4SLinus Torvalds return 0; 26928e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 26931da177e4SLinus Torvalds return 0; 269423adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 26951da177e4SLinus Torvalds } 2696cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 26971da177e4SLinus Torvalds 26981da177e4SLinus Torvalds /* 26991da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 27001da177e4SLinus Torvalds * whether the type of victim is right. 27011da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 27021da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 27031da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 27041da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 27051da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 27061da177e4SLinus Torvalds * a. be owner of dir, or 27071da177e4SLinus Torvalds * b. be owner of victim, or 27081da177e4SLinus Torvalds * c. have CAP_FOWNER capability 27091da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 27101da177e4SLinus Torvalds * links pointing to it. 27110bd23d09SEric W. Biederman * 7. If the victim has an unknown uid or gid we can't change the inode. 27120bd23d09SEric W. Biederman * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. 27130bd23d09SEric W. Biederman * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. 27140bd23d09SEric W. Biederman * 10. We can't remove a root or mountpoint. 27150bd23d09SEric W. Biederman * 11. We don't allow removal of NFS sillyrenamed files; it's handled by 27161da177e4SLinus Torvalds * nfs_async_unlink(). 27171da177e4SLinus Torvalds */ 2718b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 27191da177e4SLinus Torvalds { 272063afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 27211da177e4SLinus Torvalds int error; 27221da177e4SLinus Torvalds 2723b18825a7SDavid Howells if (d_is_negative(victim)) 27241da177e4SLinus Torvalds return -ENOENT; 2725b18825a7SDavid Howells BUG_ON(!inode); 27261da177e4SLinus Torvalds 27271da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 27284fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 27291da177e4SLinus Torvalds 2730f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 27311da177e4SLinus Torvalds if (error) 27321da177e4SLinus Torvalds return error; 27331da177e4SLinus Torvalds if (IS_APPEND(dir)) 27341da177e4SLinus Torvalds return -EPERM; 2735b18825a7SDavid Howells 2736b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 27370bd23d09SEric W. Biederman IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) 27381da177e4SLinus Torvalds return -EPERM; 27391da177e4SLinus Torvalds if (isdir) { 274044b1d530SMiklos Szeredi if (!d_is_dir(victim)) 27411da177e4SLinus Torvalds return -ENOTDIR; 27421da177e4SLinus Torvalds if (IS_ROOT(victim)) 27431da177e4SLinus Torvalds return -EBUSY; 274444b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 27451da177e4SLinus Torvalds return -EISDIR; 27461da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27471da177e4SLinus Torvalds return -ENOENT; 27481da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 27491da177e4SLinus Torvalds return -EBUSY; 27501da177e4SLinus Torvalds return 0; 27511da177e4SLinus Torvalds } 27521da177e4SLinus Torvalds 27531da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 27541da177e4SLinus Torvalds * dir. 27551da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 27561da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 27571da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 2758036d5236SEric W. Biederman * 3. We can't do it if the fs can't represent the fsuid or fsgid. 2759036d5236SEric W. Biederman * 4. We should have write and exec permissions on dir 2760036d5236SEric W. Biederman * 5. We can't do it if dir is immutable (done in permission()) 27611da177e4SLinus Torvalds */ 2762a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 27631da177e4SLinus Torvalds { 2764036d5236SEric W. Biederman struct user_namespace *s_user_ns; 276514e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 27661da177e4SLinus Torvalds if (child->d_inode) 27671da177e4SLinus Torvalds return -EEXIST; 27681da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27691da177e4SLinus Torvalds return -ENOENT; 2770036d5236SEric W. Biederman s_user_ns = dir->i_sb->s_user_ns; 2771036d5236SEric W. Biederman if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 2772036d5236SEric W. Biederman !kgid_has_mapping(s_user_ns, current_fsgid())) 2773036d5236SEric W. Biederman return -EOVERFLOW; 2774f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 27751da177e4SLinus Torvalds } 27761da177e4SLinus Torvalds 27771da177e4SLinus Torvalds /* 27781da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 27791da177e4SLinus Torvalds */ 27801da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 27811da177e4SLinus Torvalds { 27821da177e4SLinus Torvalds struct dentry *p; 27831da177e4SLinus Torvalds 27841da177e4SLinus Torvalds if (p1 == p2) { 27855955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27861da177e4SLinus Torvalds return NULL; 27871da177e4SLinus Torvalds } 27881da177e4SLinus Torvalds 2789fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 27901da177e4SLinus Torvalds 2791e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2792e2761a11SOGAWA Hirofumi if (p) { 27935955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 27945955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 27951da177e4SLinus Torvalds return p; 27961da177e4SLinus Torvalds } 27971da177e4SLinus Torvalds 2798e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2799e2761a11SOGAWA Hirofumi if (p) { 28005955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28015955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 28021da177e4SLinus Torvalds return p; 28031da177e4SLinus Torvalds } 28041da177e4SLinus Torvalds 28055955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28065955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 28071da177e4SLinus Torvalds return NULL; 28081da177e4SLinus Torvalds } 28094d359507SAl Viro EXPORT_SYMBOL(lock_rename); 28101da177e4SLinus Torvalds 28111da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 28121da177e4SLinus Torvalds { 28135955102cSAl Viro inode_unlock(p1->d_inode); 28141da177e4SLinus Torvalds if (p1 != p2) { 28155955102cSAl Viro inode_unlock(p2->d_inode); 2816fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 28171da177e4SLinus Torvalds } 28181da177e4SLinus Torvalds } 28194d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 28201da177e4SLinus Torvalds 28214acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2822312b63fbSAl Viro bool want_excl) 28231da177e4SLinus Torvalds { 2824a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28251da177e4SLinus Torvalds if (error) 28261da177e4SLinus Torvalds return error; 28271da177e4SLinus Torvalds 2828acfa4380SAl Viro if (!dir->i_op->create) 28291da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 28301da177e4SLinus Torvalds mode &= S_IALLUGO; 28311da177e4SLinus Torvalds mode |= S_IFREG; 28321da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 28331da177e4SLinus Torvalds if (error) 28341da177e4SLinus Torvalds return error; 2835312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2836a74574aaSStephen Smalley if (!error) 2837f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28381da177e4SLinus Torvalds return error; 28391da177e4SLinus Torvalds } 28404d359507SAl Viro EXPORT_SYMBOL(vfs_create); 28411da177e4SLinus Torvalds 2842a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 2843a2982cc9SEric W. Biederman { 2844a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 2845a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 2846a2982cc9SEric W. Biederman } 2847a2982cc9SEric W. Biederman 2848f0bb5aafSAl Viro static int may_open(const struct path *path, int acc_mode, int flag) 28491da177e4SLinus Torvalds { 28503fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 28511da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 28521da177e4SLinus Torvalds int error; 28531da177e4SLinus Torvalds 28541da177e4SLinus Torvalds if (!inode) 28551da177e4SLinus Torvalds return -ENOENT; 28561da177e4SLinus Torvalds 2857c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2858c8fe8f30SChristoph Hellwig case S_IFLNK: 28591da177e4SLinus Torvalds return -ELOOP; 2860c8fe8f30SChristoph Hellwig case S_IFDIR: 2861c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 28621da177e4SLinus Torvalds return -EISDIR; 2863c8fe8f30SChristoph Hellwig break; 2864c8fe8f30SChristoph Hellwig case S_IFBLK: 2865c8fe8f30SChristoph Hellwig case S_IFCHR: 2866a2982cc9SEric W. Biederman if (!may_open_dev(path)) 28671da177e4SLinus Torvalds return -EACCES; 2868c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2869c8fe8f30SChristoph Hellwig case S_IFIFO: 2870c8fe8f30SChristoph Hellwig case S_IFSOCK: 28711da177e4SLinus Torvalds flag &= ~O_TRUNC; 2872c8fe8f30SChristoph Hellwig break; 28734a3fd211SDave Hansen } 2874b41572e9SDave Hansen 287562fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2876b41572e9SDave Hansen if (error) 2877b41572e9SDave Hansen return error; 28786146f0d5SMimi Zohar 28791da177e4SLinus Torvalds /* 28801da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 28811da177e4SLinus Torvalds */ 28821da177e4SLinus Torvalds if (IS_APPEND(inode)) { 28838737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 28847715b521SAl Viro return -EPERM; 28851da177e4SLinus Torvalds if (flag & O_TRUNC) 28867715b521SAl Viro return -EPERM; 28871da177e4SLinus Torvalds } 28881da177e4SLinus Torvalds 28891da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 28902e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 28917715b521SAl Viro return -EPERM; 28921da177e4SLinus Torvalds 2893f3c7691eSJ. Bruce Fields return 0; 28947715b521SAl Viro } 28957715b521SAl Viro 2896e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 28977715b521SAl Viro { 2898f0bb5aafSAl Viro const struct path *path = &filp->f_path; 28997715b521SAl Viro struct inode *inode = path->dentry->d_inode; 29007715b521SAl Viro int error = get_write_access(inode); 29011da177e4SLinus Torvalds if (error) 29027715b521SAl Viro return error; 29031da177e4SLinus Torvalds /* 29041da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 29051da177e4SLinus Torvalds */ 2906d7a06983SJeff Layton error = locks_verify_locked(filp); 2907be6d3e56SKentaro Takeda if (!error) 2908ea0d3ab2STetsuo Handa error = security_path_truncate(path); 29091da177e4SLinus Torvalds if (!error) { 29107715b521SAl Viro error = do_truncate(path->dentry, 0, 2911d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2912e1181ee6SJeff Layton filp); 29131da177e4SLinus Torvalds } 29141da177e4SLinus Torvalds put_write_access(inode); 2915acd0c935SMimi Zohar return error; 29161da177e4SLinus Torvalds } 29171da177e4SLinus Torvalds 2918d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2919d57999e1SDave Hansen { 29208a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 29218a5e929dSAl Viro flag--; 2922d57999e1SDave Hansen return flag; 2923d57999e1SDave Hansen } 2924d57999e1SDave Hansen 2925d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 2926d18e9008SMiklos Szeredi { 2927d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2928d18e9008SMiklos Szeredi if (error) 2929d18e9008SMiklos Szeredi return error; 2930d18e9008SMiklos Szeredi 2931d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2932d18e9008SMiklos Szeredi if (error) 2933d18e9008SMiklos Szeredi return error; 2934d18e9008SMiklos Szeredi 2935d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2936d18e9008SMiklos Szeredi } 2937d18e9008SMiklos Szeredi 29381acf0af9SDavid Howells /* 29391acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 29401acf0af9SDavid Howells * dentry. 29411acf0af9SDavid Howells * 29421acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 29431acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 29441acf0af9SDavid Howells * 29451acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 29461acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 29471acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 29481acf0af9SDavid Howells * 29491acf0af9SDavid Howells * Returns an error code otherwise. 29501acf0af9SDavid Howells */ 29512675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 295230d90494SAl Viro struct path *path, struct file *file, 2953015c3bbcSMiklos Szeredi const struct open_flags *op, 29541643b43fSAl Viro int open_flag, umode_t mode, 295547237687SAl Viro int *opened) 2956d18e9008SMiklos Szeredi { 2957d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2958d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2959d18e9008SMiklos Szeredi int error; 2960d18e9008SMiklos Szeredi 2961384f26e2SAl Viro if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ 2962d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2963d18e9008SMiklos Szeredi 2964d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2965d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2966d18e9008SMiklos Szeredi 296730d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 296830d90494SAl Viro file->f_path.mnt = nd->path.mnt; 29690fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 29700fb1ea09SAl Viro open_to_namei_flags(open_flag), 29710fb1ea09SAl Viro mode, opened); 29726fbd0714SAl Viro d_lookup_done(dentry); 2973384f26e2SAl Viro if (!error) { 2974d18e9008SMiklos Szeredi /* 2975384f26e2SAl Viro * We didn't have the inode before the open, so check open 2976384f26e2SAl Viro * permission here. 2977d18e9008SMiklos Szeredi */ 2978384f26e2SAl Viro int acc_mode = op->acc_mode; 297903da633aSAl Viro if (*opened & FILE_CREATED) { 298003da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 298103da633aSAl Viro fsnotify_create(dir, dentry); 298262fb4a15SAl Viro acc_mode = 0; 298303da633aSAl Viro } 29842675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 2985384f26e2SAl Viro if (WARN_ON(error > 0)) 2986384f26e2SAl Viro error = -EINVAL; 2987384f26e2SAl Viro } else if (error > 0) { 2988d18e9008SMiklos Szeredi if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 2989d18e9008SMiklos Szeredi error = -EIO; 2990384f26e2SAl Viro } else { 2991d18e9008SMiklos Szeredi if (file->f_path.dentry) { 2992d18e9008SMiklos Szeredi dput(dentry); 2993d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 299410c64ceaSAl Viro } 2995d18e9008SMiklos Szeredi if (*opened & FILE_CREATED) 2996d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 2997a01e718fSAl Viro if (unlikely(d_is_negative(dentry))) { 2998a01e718fSAl Viro error = -ENOENT; 2999a01e718fSAl Viro } else { 3000d18e9008SMiklos Szeredi path->dentry = dentry; 3001d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 30022675a4ebSAl Viro return 1; 3003d18e9008SMiklos Szeredi } 3004d18e9008SMiklos Szeredi } 3005a01e718fSAl Viro } 3006d18e9008SMiklos Szeredi dput(dentry); 3007d18e9008SMiklos Szeredi return error; 3008d18e9008SMiklos Szeredi } 3009d18e9008SMiklos Szeredi 301031e6b01fSNick Piggin /* 30111acf0af9SDavid Howells * Look up and maybe create and open the last component. 3012d58ffd35SMiklos Szeredi * 3013d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 3014d58ffd35SMiklos Szeredi * 30151acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 30161acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 30171acf0af9SDavid Howells * 30181acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 30191acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 30201acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 30211acf0af9SDavid Howells * specified then a negative dentry may be returned. 30221acf0af9SDavid Howells * 30231acf0af9SDavid Howells * An error code is returned otherwise. 30241acf0af9SDavid Howells * 30251acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 30261acf0af9SDavid Howells * cleared otherwise prior to returning. 3027d58ffd35SMiklos Szeredi */ 30282675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 302930d90494SAl Viro struct file *file, 3030d58ffd35SMiklos Szeredi const struct open_flags *op, 303164894cf8SAl Viro bool got_write, int *opened) 3032d58ffd35SMiklos Szeredi { 3033d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 303454ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 30351643b43fSAl Viro int open_flag = op->open_flag; 3036d58ffd35SMiklos Szeredi struct dentry *dentry; 30371643b43fSAl Viro int error, create_error = 0; 30381643b43fSAl Viro umode_t mode = op->mode; 30396fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3040d58ffd35SMiklos Szeredi 3041ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3042ce8644fcSAl Viro return -ENOENT; 3043d58ffd35SMiklos Szeredi 304447237687SAl Viro *opened &= ~FILE_CREATED; 30456fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 30466fbd0714SAl Viro for (;;) { 30476fbd0714SAl Viro if (!dentry) { 30486fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3049d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 30502675a4ebSAl Viro return PTR_ERR(dentry); 30516fbd0714SAl Viro } 30526fbd0714SAl Viro if (d_in_lookup(dentry)) 30536fbd0714SAl Viro break; 3054d58ffd35SMiklos Szeredi 30556fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 30566fbd0714SAl Viro if (likely(error > 0)) 30576fbd0714SAl Viro break; 30586fbd0714SAl Viro if (error) 30596fbd0714SAl Viro goto out_dput; 30606fbd0714SAl Viro d_invalidate(dentry); 30616fbd0714SAl Viro dput(dentry); 30626fbd0714SAl Viro dentry = NULL; 30636fbd0714SAl Viro } 30646fbd0714SAl Viro if (dentry->d_inode) { 3065d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3066d18e9008SMiklos Szeredi goto out_no_open; 30676c51e513SAl Viro } 3068d18e9008SMiklos Szeredi 30691643b43fSAl Viro /* 30701643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 30711643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 30721643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 30731643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 30741643b43fSAl Viro * 30751643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 30761643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 30771643b43fSAl Viro */ 30781643b43fSAl Viro if (open_flag & O_CREAT) { 30791643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 30801643b43fSAl Viro mode &= ~current_umask(); 30811643b43fSAl Viro if (unlikely(!got_write)) { 30821643b43fSAl Viro create_error = -EROFS; 30831643b43fSAl Viro open_flag &= ~O_CREAT; 30841643b43fSAl Viro if (open_flag & (O_EXCL | O_TRUNC)) 30851643b43fSAl Viro goto no_open; 30861643b43fSAl Viro /* No side effects, safe to clear O_CREAT */ 30871643b43fSAl Viro } else { 30881643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 30891643b43fSAl Viro if (create_error) { 30901643b43fSAl Viro open_flag &= ~O_CREAT; 30911643b43fSAl Viro if (open_flag & O_EXCL) 30921643b43fSAl Viro goto no_open; 30931643b43fSAl Viro } 30941643b43fSAl Viro } 30951643b43fSAl Viro } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && 30961643b43fSAl Viro unlikely(!got_write)) { 30971643b43fSAl Viro /* 30981643b43fSAl Viro * No O_CREATE -> atomicity not a requirement -> fall 30991643b43fSAl Viro * back to lookup + open 31001643b43fSAl Viro */ 31011643b43fSAl Viro goto no_open; 3102d18e9008SMiklos Szeredi } 3103d18e9008SMiklos Szeredi 31041643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 31051643b43fSAl Viro error = atomic_open(nd, dentry, path, file, op, open_flag, 31061643b43fSAl Viro mode, opened); 31071643b43fSAl Viro if (unlikely(error == -ENOENT) && create_error) 31081643b43fSAl Viro error = create_error; 31091643b43fSAl Viro return error; 31101643b43fSAl Viro } 311154ef4872SMiklos Szeredi 31121643b43fSAl Viro no_open: 31136fbd0714SAl Viro if (d_in_lookup(dentry)) { 311412fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 311512fa5e24SAl Viro nd->flags); 31166fbd0714SAl Viro d_lookup_done(dentry); 311712fa5e24SAl Viro if (unlikely(res)) { 311812fa5e24SAl Viro if (IS_ERR(res)) { 311912fa5e24SAl Viro error = PTR_ERR(res); 312012fa5e24SAl Viro goto out_dput; 312112fa5e24SAl Viro } 312212fa5e24SAl Viro dput(dentry); 312312fa5e24SAl Viro dentry = res; 312412fa5e24SAl Viro } 312554ef4872SMiklos Szeredi } 312654ef4872SMiklos Szeredi 3127d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 31281643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 312947237687SAl Viro *opened |= FILE_CREATED; 3130ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3131ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3132ce8644fcSAl Viro error = -EACCES; 3133d58ffd35SMiklos Szeredi goto out_dput; 313477d660a8SMiklos Szeredi } 3135ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 31361643b43fSAl Viro open_flag & O_EXCL); 3137d58ffd35SMiklos Szeredi if (error) 3138d58ffd35SMiklos Szeredi goto out_dput; 3139ce8644fcSAl Viro fsnotify_create(dir_inode, dentry); 3140d58ffd35SMiklos Szeredi } 31411643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 31421643b43fSAl Viro error = create_error; 3143d58ffd35SMiklos Szeredi goto out_dput; 3144d58ffd35SMiklos Szeredi } 3145d18e9008SMiklos Szeredi out_no_open: 3146d58ffd35SMiklos Szeredi path->dentry = dentry; 3147d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 31482675a4ebSAl Viro return 1; 3149d58ffd35SMiklos Szeredi 3150d58ffd35SMiklos Szeredi out_dput: 3151d58ffd35SMiklos Szeredi dput(dentry); 31522675a4ebSAl Viro return error; 3153d58ffd35SMiklos Szeredi } 3154d58ffd35SMiklos Szeredi 3155d58ffd35SMiklos Szeredi /* 3156fe2d35ffSAl Viro * Handle the last step of open() 315731e6b01fSNick Piggin */ 3158896475d5SAl Viro static int do_last(struct nameidata *nd, 315930d90494SAl Viro struct file *file, const struct open_flags *op, 316076ae2a5aSAl Viro int *opened) 3161fb1cc555SAl Viro { 3162a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3163ca344a89SAl Viro int open_flag = op->open_flag; 316477d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 316564894cf8SAl Viro bool got_write = false; 3166bcda7652SAl Viro int acc_mode = op->acc_mode; 3167254cf582SAl Viro unsigned seq; 3168a1eb3315SMiklos Szeredi struct inode *inode; 3169896475d5SAl Viro struct path path; 317016c2cd71SAl Viro int error; 3171fb1cc555SAl Viro 3172c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3173c3e380b0SAl Viro nd->flags |= op->intent; 3174c3e380b0SAl Viro 3175bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3176fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3177deb106c6SAl Viro if (unlikely(error)) 31782675a4ebSAl Viro return error; 3179e83db167SMiklos Szeredi goto finish_open; 31801f36f774SAl Viro } 3181a2c36b45SAl Viro 3182ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3183fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3184fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3185fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3186254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 3187e9742b53SAl Viro if (likely(error > 0)) 318871574865SMiklos Szeredi goto finish_lookup; 318971574865SMiklos Szeredi 3190ce57dfc1SAl Viro if (error < 0) 3191deb106c6SAl Viro return error; 3192a1eb3315SMiklos Szeredi 319337d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 31946583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3195b6183df7SMiklos Szeredi } else { 3196fe2d35ffSAl Viro /* create side of things */ 3197a3fbbde7SAl Viro /* 3198b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3199b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3200b6183df7SMiklos Szeredi * about to look up 3201a3fbbde7SAl Viro */ 32029f1fafeeSAl Viro error = complete_walk(nd); 3203e8bb73dfSAl Viro if (error) 32042675a4ebSAl Viro return error; 3205fe2d35ffSAl Viro 320676ae2a5aSAl Viro audit_inode(nd->name, dir, LOOKUP_PARENT); 32071f36f774SAl Viro /* trailing slashes? */ 3208deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3209deb106c6SAl Viro return -EISDIR; 3210b6183df7SMiklos Szeredi } 32111f36f774SAl Viro 32129cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 321364894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 321464894cf8SAl Viro if (!error) 321564894cf8SAl Viro got_write = true; 321664894cf8SAl Viro /* 321764894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 321864894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 321964894cf8SAl Viro * dropping this one anyway. 322064894cf8SAl Viro */ 322164894cf8SAl Viro } 32229cf843e3SAl Viro if (open_flag & O_CREAT) 32235955102cSAl Viro inode_lock(dir->d_inode); 32249cf843e3SAl Viro else 32259cf843e3SAl Viro inode_lock_shared(dir->d_inode); 3226896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 32279cf843e3SAl Viro if (open_flag & O_CREAT) 32285955102cSAl Viro inode_unlock(dir->d_inode); 32299cf843e3SAl Viro else 32309cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3231fb1cc555SAl Viro 32322675a4ebSAl Viro if (error <= 0) { 32332675a4ebSAl Viro if (error) 3234d58ffd35SMiklos Szeredi goto out; 32356c0d46c4SAl Viro 323647237687SAl Viro if ((*opened & FILE_CREATED) || 3237496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 323877d660a8SMiklos Szeredi will_truncate = false; 3239d18e9008SMiklos Szeredi 324076ae2a5aSAl Viro audit_inode(nd->name, file->f_path.dentry, 0); 3241d18e9008SMiklos Szeredi goto opened; 3242d18e9008SMiklos Szeredi } 3243d18e9008SMiklos Szeredi 324447237687SAl Viro if (*opened & FILE_CREATED) { 32459b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3246ca344a89SAl Viro open_flag &= ~O_TRUNC; 324777d660a8SMiklos Szeredi will_truncate = false; 324862fb4a15SAl Viro acc_mode = 0; 3249896475d5SAl Viro path_to_nameidata(&path, nd); 3250e83db167SMiklos Szeredi goto finish_open_created; 3251fb1cc555SAl Viro } 3252fb1cc555SAl Viro 3253fb1cc555SAl Viro /* 3254d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3255d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3256d18e9008SMiklos Szeredi * necessary...) 3257d18e9008SMiklos Szeredi */ 325864894cf8SAl Viro if (got_write) { 3259d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 326064894cf8SAl Viro got_write = false; 3261d18e9008SMiklos Szeredi } 3262d18e9008SMiklos Szeredi 3263e6ec03a2SAl Viro error = follow_managed(&path, nd); 3264e6ec03a2SAl Viro if (unlikely(error < 0)) 3265e6ec03a2SAl Viro return error; 3266e6ec03a2SAl Viro 32676583fe22SAl Viro if (unlikely(d_is_negative(path.dentry))) { 32686583fe22SAl Viro path_to_nameidata(&path, nd); 32696583fe22SAl Viro return -ENOENT; 32706583fe22SAl Viro } 32716583fe22SAl Viro 32726583fe22SAl Viro /* 32736583fe22SAl Viro * create/update audit record if it already exists. 32746583fe22SAl Viro */ 32756583fe22SAl Viro audit_inode(nd->name, path.dentry, 0); 32766583fe22SAl Viro 3277deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3278deb106c6SAl Viro path_to_nameidata(&path, nd); 3279deb106c6SAl Viro return -EEXIST; 3280deb106c6SAl Viro } 3281fb1cc555SAl Viro 3282254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3283d4565649SAl Viro inode = d_backing_inode(path.dentry); 3284766c4cbfSAl Viro finish_lookup: 32858f64fb1cSAl Viro error = step_into(nd, &path, 0, inode, seq); 3286deb106c6SAl Viro if (unlikely(error)) 3287d63ff28fSAl Viro return error; 3288bc77daa7SAl Viro finish_open: 32898f64fb1cSAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3290a3fbbde7SAl Viro error = complete_walk(nd); 3291fac7d191SAl Viro if (error) 32922675a4ebSAl Viro return error; 329376ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 3294fb1cc555SAl Viro error = -EISDIR; 329544b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 32962675a4ebSAl Viro goto out; 3297af2f5542SMiklos Szeredi error = -ENOTDIR; 329844b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 32992675a4ebSAl Viro goto out; 33004bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 330177d660a8SMiklos Szeredi will_truncate = false; 33026c0d46c4SAl Viro 33030f9d1a10SAl Viro if (will_truncate) { 33040f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 33050f9d1a10SAl Viro if (error) 33062675a4ebSAl Viro goto out; 330764894cf8SAl Viro got_write = true; 33080f9d1a10SAl Viro } 3309e83db167SMiklos Szeredi finish_open_created: 3310bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3311ca344a89SAl Viro if (error) 33122675a4ebSAl Viro goto out; 33134aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 33144aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 3315fac7d191SAl Viro if (error) 3316015c3bbcSMiklos Szeredi goto out; 3317fac7d191SAl Viro *opened |= FILE_OPENED; 3318a8277b9bSMiklos Szeredi opened: 33192675a4ebSAl Viro error = open_check_o_direct(file); 3320fe9ec829SAl Viro if (!error) 33213034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3322fe9ec829SAl Viro if (!error && will_truncate) 33232675a4ebSAl Viro error = handle_truncate(file); 3324ca344a89SAl Viro out: 3325fe9ec829SAl Viro if (unlikely(error) && (*opened & FILE_OPENED)) 3326fe9ec829SAl Viro fput(file); 3327c80567c8SAl Viro if (unlikely(error > 0)) { 3328c80567c8SAl Viro WARN_ON(1); 3329c80567c8SAl Viro error = -EINVAL; 3330c80567c8SAl Viro } 333164894cf8SAl Viro if (got_write) 33320f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 33332675a4ebSAl Viro return error; 3334fb1cc555SAl Viro } 3335fb1cc555SAl Viro 3336c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 333760545d0dSAl Viro const struct open_flags *op, 333860545d0dSAl Viro struct file *file, int *opened) 333960545d0dSAl Viro { 334060545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 3341625b6d10SAl Viro struct dentry *child; 334260545d0dSAl Viro struct inode *dir; 3343625b6d10SAl Viro struct path path; 3344c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 334560545d0dSAl Viro if (unlikely(error)) 334660545d0dSAl Viro return error; 3347625b6d10SAl Viro error = mnt_want_write(path.mnt); 334860545d0dSAl Viro if (unlikely(error)) 334960545d0dSAl Viro goto out; 3350625b6d10SAl Viro dir = path.dentry->d_inode; 335160545d0dSAl Viro /* we want directory to be writable */ 3352625b6d10SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 335360545d0dSAl Viro if (error) 335460545d0dSAl Viro goto out2; 335560545d0dSAl Viro if (!dir->i_op->tmpfile) { 335660545d0dSAl Viro error = -EOPNOTSUPP; 335760545d0dSAl Viro goto out2; 335860545d0dSAl Viro } 3359625b6d10SAl Viro child = d_alloc(path.dentry, &name); 336060545d0dSAl Viro if (unlikely(!child)) { 336160545d0dSAl Viro error = -ENOMEM; 336260545d0dSAl Viro goto out2; 336360545d0dSAl Viro } 3364625b6d10SAl Viro dput(path.dentry); 3365625b6d10SAl Viro path.dentry = child; 3366625b6d10SAl Viro error = dir->i_op->tmpfile(dir, child, op->mode); 336760545d0dSAl Viro if (error) 336860545d0dSAl Viro goto out2; 3369c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 337069a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 337162fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 337260545d0dSAl Viro if (error) 337360545d0dSAl Viro goto out2; 3374625b6d10SAl Viro file->f_path.mnt = path.mnt; 3375625b6d10SAl Viro error = finish_open(file, child, NULL, opened); 337660545d0dSAl Viro if (error) 337760545d0dSAl Viro goto out2; 337860545d0dSAl Viro error = open_check_o_direct(file); 3379f4e0c30cSAl Viro if (error) { 338060545d0dSAl Viro fput(file); 3381f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3382f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3383f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3384f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3385f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3386f4e0c30cSAl Viro } 338760545d0dSAl Viro out2: 3388625b6d10SAl Viro mnt_drop_write(path.mnt); 338960545d0dSAl Viro out: 3390625b6d10SAl Viro path_put(&path); 339160545d0dSAl Viro return error; 339260545d0dSAl Viro } 339360545d0dSAl Viro 33946ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 33956ac08709SAl Viro { 33966ac08709SAl Viro struct path path; 33976ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 33986ac08709SAl Viro if (!error) { 33996ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 34006ac08709SAl Viro error = vfs_open(&path, file, current_cred()); 34016ac08709SAl Viro path_put(&path); 34026ac08709SAl Viro } 34036ac08709SAl Viro return error; 34046ac08709SAl Viro } 34056ac08709SAl Viro 3406c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3407c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 34081da177e4SLinus Torvalds { 3409368ee9baSAl Viro const char *s; 341030d90494SAl Viro struct file *file; 341147237687SAl Viro int opened = 0; 341213aab428SAl Viro int error; 341331e6b01fSNick Piggin 341430d90494SAl Viro file = get_empty_filp(); 34151afc99beSAl Viro if (IS_ERR(file)) 34161afc99beSAl Viro return file; 341731e6b01fSNick Piggin 341830d90494SAl Viro file->f_flags = op->open_flag; 341931e6b01fSNick Piggin 3420bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 3421c8a53ee5SAl Viro error = do_tmpfile(nd, flags, op, file, &opened); 3422f15133dfSAl Viro goto out2; 342360545d0dSAl Viro } 342460545d0dSAl Viro 34256ac08709SAl Viro if (unlikely(file->f_flags & O_PATH)) { 34266ac08709SAl Viro error = do_o_path(nd, flags, file); 34276ac08709SAl Viro if (!error) 34286ac08709SAl Viro opened |= FILE_OPENED; 34296ac08709SAl Viro goto out2; 34306ac08709SAl Viro } 34316ac08709SAl Viro 3432c8a53ee5SAl Viro s = path_init(nd, flags); 3433368ee9baSAl Viro if (IS_ERR(s)) { 3434368ee9baSAl Viro put_filp(file); 3435368ee9baSAl Viro return ERR_CAST(s); 3436368ee9baSAl Viro } 34373bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 343876ae2a5aSAl Viro (error = do_last(nd, file, op, &opened)) > 0) { 343973d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 34403bdba28bSAl Viro s = trailing_symlink(nd); 34413bdba28bSAl Viro if (IS_ERR(s)) { 34423bdba28bSAl Viro error = PTR_ERR(s); 34432675a4ebSAl Viro break; 3444806b681cSAl Viro } 34453bdba28bSAl Viro } 3446deb106c6SAl Viro terminate_walk(nd); 3447f15133dfSAl Viro out2: 34482675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 34492675a4ebSAl Viro BUG_ON(!error); 345030d90494SAl Viro put_filp(file); 3451015c3bbcSMiklos Szeredi } 34522675a4ebSAl Viro if (unlikely(error)) { 34532675a4ebSAl Viro if (error == -EOPENSTALE) { 34542675a4ebSAl Viro if (flags & LOOKUP_RCU) 34552675a4ebSAl Viro error = -ECHILD; 34562675a4ebSAl Viro else 34572675a4ebSAl Viro error = -ESTALE; 34582675a4ebSAl Viro } 34592675a4ebSAl Viro file = ERR_PTR(error); 34602675a4ebSAl Viro } 34612675a4ebSAl Viro return file; 3462de459215SKirill Korotaev } 34631da177e4SLinus Torvalds 3464669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3465f9652e10SAl Viro const struct open_flags *op) 346613aab428SAl Viro { 34679883d185SAl Viro struct nameidata nd; 3468f9652e10SAl Viro int flags = op->lookup_flags; 346913aab428SAl Viro struct file *filp; 347013aab428SAl Viro 34719883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3472c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 347313aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3474c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 347513aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3476c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 34779883d185SAl Viro restore_nameidata(); 347813aab428SAl Viro return filp; 347913aab428SAl Viro } 348013aab428SAl Viro 348173d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3482f9652e10SAl Viro const char *name, const struct open_flags *op) 348373d049a4SAl Viro { 34849883d185SAl Viro struct nameidata nd; 348573d049a4SAl Viro struct file *file; 348651689104SPaul Moore struct filename *filename; 3487f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 348873d049a4SAl Viro 348973d049a4SAl Viro nd.root.mnt = mnt; 349073d049a4SAl Viro nd.root.dentry = dentry; 349173d049a4SAl Viro 3492b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 349373d049a4SAl Viro return ERR_PTR(-ELOOP); 349473d049a4SAl Viro 349551689104SPaul Moore filename = getname_kernel(name); 3496a1c83681SViresh Kumar if (IS_ERR(filename)) 349751689104SPaul Moore return ERR_CAST(filename); 349851689104SPaul Moore 34999883d185SAl Viro set_nameidata(&nd, -1, filename); 3500c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 350173d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3502c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 350373d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3504c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 35059883d185SAl Viro restore_nameidata(); 350651689104SPaul Moore putname(filename); 350773d049a4SAl Viro return file; 350873d049a4SAl Viro } 350973d049a4SAl Viro 3510fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 35111ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 35121da177e4SLinus Torvalds { 3513c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3514391172c4SAl Viro struct qstr last; 3515391172c4SAl Viro int type; 3516c30dabfeSJan Kara int err2; 35171ac12b4bSJeff Layton int error; 35181ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 35191ac12b4bSJeff Layton 35201ac12b4bSJeff Layton /* 35211ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 35221ac12b4bSJeff Layton * other flags passed in are ignored! 35231ac12b4bSJeff Layton */ 35241ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 35251ac12b4bSJeff Layton 35265c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 35275c31b6ceSAl Viro if (IS_ERR(name)) 35285c31b6ceSAl Viro return ERR_CAST(name); 35291da177e4SLinus Torvalds 3530c663e5d8SChristoph Hellwig /* 3531c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3532c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3533c663e5d8SChristoph Hellwig */ 35345c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3535ed75e95dSAl Viro goto out; 3536c663e5d8SChristoph Hellwig 3537c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3538391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3539c663e5d8SChristoph Hellwig /* 3540c663e5d8SChristoph Hellwig * Do the final lookup. 3541c663e5d8SChristoph Hellwig */ 3542391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 35435955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3544391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 35451da177e4SLinus Torvalds if (IS_ERR(dentry)) 3546a8104a9fSAl Viro goto unlock; 3547c663e5d8SChristoph Hellwig 3548a8104a9fSAl Viro error = -EEXIST; 3549b18825a7SDavid Howells if (d_is_positive(dentry)) 3550a8104a9fSAl Viro goto fail; 3551b18825a7SDavid Howells 3552c663e5d8SChristoph Hellwig /* 3553c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3554c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3555c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3556c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3557c663e5d8SChristoph Hellwig */ 3558391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3559a8104a9fSAl Viro error = -ENOENT; 3560ed75e95dSAl Viro goto fail; 3561e9baf6e5SAl Viro } 3562c30dabfeSJan Kara if (unlikely(err2)) { 3563c30dabfeSJan Kara error = err2; 3564a8104a9fSAl Viro goto fail; 3565c30dabfeSJan Kara } 3566181c37b6SAl Viro putname(name); 3567e9baf6e5SAl Viro return dentry; 35681da177e4SLinus Torvalds fail: 3569a8104a9fSAl Viro dput(dentry); 3570a8104a9fSAl Viro dentry = ERR_PTR(error); 3571a8104a9fSAl Viro unlock: 35725955102cSAl Viro inode_unlock(path->dentry->d_inode); 3573c30dabfeSJan Kara if (!err2) 3574391172c4SAl Viro mnt_drop_write(path->mnt); 3575ed75e95dSAl Viro out: 3576391172c4SAl Viro path_put(path); 3577181c37b6SAl Viro putname(name); 3578ed75e95dSAl Viro return dentry; 3579dae6ad8fSAl Viro } 3580fa14a0b8SAl Viro 3581fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3582fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3583fa14a0b8SAl Viro { 3584181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3585181c37b6SAl Viro path, lookup_flags); 3586fa14a0b8SAl Viro } 3587dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3588dae6ad8fSAl Viro 3589921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3590921a1650SAl Viro { 3591921a1650SAl Viro dput(dentry); 35925955102cSAl Viro inode_unlock(path->dentry->d_inode); 3593a8104a9fSAl Viro mnt_drop_write(path->mnt); 3594921a1650SAl Viro path_put(path); 3595921a1650SAl Viro } 3596921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3597921a1650SAl Viro 3598520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 35991ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3600dae6ad8fSAl Viro { 3601181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3602dae6ad8fSAl Viro } 3603dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3604dae6ad8fSAl Viro 36051a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 36061da177e4SLinus Torvalds { 3607a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36081da177e4SLinus Torvalds 36091da177e4SLinus Torvalds if (error) 36101da177e4SLinus Torvalds return error; 36111da177e4SLinus Torvalds 3612975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 36131da177e4SLinus Torvalds return -EPERM; 36141da177e4SLinus Torvalds 3615acfa4380SAl Viro if (!dir->i_op->mknod) 36161da177e4SLinus Torvalds return -EPERM; 36171da177e4SLinus Torvalds 361808ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 361908ce5f16SSerge E. Hallyn if (error) 362008ce5f16SSerge E. Hallyn return error; 362108ce5f16SSerge E. Hallyn 36221da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 36231da177e4SLinus Torvalds if (error) 36241da177e4SLinus Torvalds return error; 36251da177e4SLinus Torvalds 36261da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3627a74574aaSStephen Smalley if (!error) 3628f38aa942SAmy Griffis fsnotify_create(dir, dentry); 36291da177e4SLinus Torvalds return error; 36301da177e4SLinus Torvalds } 36314d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 36321da177e4SLinus Torvalds 3633f69aac00SAl Viro static int may_mknod(umode_t mode) 3634463c3197SDave Hansen { 3635463c3197SDave Hansen switch (mode & S_IFMT) { 3636463c3197SDave Hansen case S_IFREG: 3637463c3197SDave Hansen case S_IFCHR: 3638463c3197SDave Hansen case S_IFBLK: 3639463c3197SDave Hansen case S_IFIFO: 3640463c3197SDave Hansen case S_IFSOCK: 3641463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3642463c3197SDave Hansen return 0; 3643463c3197SDave Hansen case S_IFDIR: 3644463c3197SDave Hansen return -EPERM; 3645463c3197SDave Hansen default: 3646463c3197SDave Hansen return -EINVAL; 3647463c3197SDave Hansen } 3648463c3197SDave Hansen } 3649463c3197SDave Hansen 36508208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 36512e4d0924SHeiko Carstens unsigned, dev) 36521da177e4SLinus Torvalds { 36531da177e4SLinus Torvalds struct dentry *dentry; 3654dae6ad8fSAl Viro struct path path; 3655dae6ad8fSAl Viro int error; 3656972567f1SJeff Layton unsigned int lookup_flags = 0; 36571da177e4SLinus Torvalds 36588e4bfca1SAl Viro error = may_mknod(mode); 36598e4bfca1SAl Viro if (error) 36608e4bfca1SAl Viro return error; 3661972567f1SJeff Layton retry: 3662972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3663dae6ad8fSAl Viro if (IS_ERR(dentry)) 3664dae6ad8fSAl Viro return PTR_ERR(dentry); 36652ad94ae6SAl Viro 3666dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3667ce3b0f8dSAl Viro mode &= ~current_umask(); 3668dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3669be6d3e56SKentaro Takeda if (error) 3670a8104a9fSAl Viro goto out; 36711da177e4SLinus Torvalds switch (mode & S_IFMT) { 36721da177e4SLinus Torvalds case 0: case S_IFREG: 3673312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 367405d1a717SMimi Zohar if (!error) 367505d1a717SMimi Zohar ima_post_path_mknod(dentry); 36761da177e4SLinus Torvalds break; 36771da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3678dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 36791da177e4SLinus Torvalds new_decode_dev(dev)); 36801da177e4SLinus Torvalds break; 36811da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3682dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 36831da177e4SLinus Torvalds break; 36841da177e4SLinus Torvalds } 3685a8104a9fSAl Viro out: 3686921a1650SAl Viro done_path_create(&path, dentry); 3687972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3688972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3689972567f1SJeff Layton goto retry; 3690972567f1SJeff Layton } 36911da177e4SLinus Torvalds return error; 36921da177e4SLinus Torvalds } 36931da177e4SLinus Torvalds 36948208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 36955590ff0dSUlrich Drepper { 36965590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 36975590ff0dSUlrich Drepper } 36985590ff0dSUlrich Drepper 369918bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 37001da177e4SLinus Torvalds { 3701a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 37028de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 37031da177e4SLinus Torvalds 37041da177e4SLinus Torvalds if (error) 37051da177e4SLinus Torvalds return error; 37061da177e4SLinus Torvalds 3707acfa4380SAl Viro if (!dir->i_op->mkdir) 37081da177e4SLinus Torvalds return -EPERM; 37091da177e4SLinus Torvalds 37101da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 37111da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 37121da177e4SLinus Torvalds if (error) 37131da177e4SLinus Torvalds return error; 37141da177e4SLinus Torvalds 37158de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 37168de52778SAl Viro return -EMLINK; 37178de52778SAl Viro 37181da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3719a74574aaSStephen Smalley if (!error) 3720f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 37211da177e4SLinus Torvalds return error; 37221da177e4SLinus Torvalds } 37234d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 37241da177e4SLinus Torvalds 3725a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 37261da177e4SLinus Torvalds { 37276902d925SDave Hansen struct dentry *dentry; 3728dae6ad8fSAl Viro struct path path; 3729dae6ad8fSAl Viro int error; 3730b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 37311da177e4SLinus Torvalds 3732b76d8b82SJeff Layton retry: 3733b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 37346902d925SDave Hansen if (IS_ERR(dentry)) 3735dae6ad8fSAl Viro return PTR_ERR(dentry); 37366902d925SDave Hansen 3737dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3738ce3b0f8dSAl Viro mode &= ~current_umask(); 3739dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3740a8104a9fSAl Viro if (!error) 3741dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3742921a1650SAl Viro done_path_create(&path, dentry); 3743b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3744b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3745b76d8b82SJeff Layton goto retry; 3746b76d8b82SJeff Layton } 37471da177e4SLinus Torvalds return error; 37481da177e4SLinus Torvalds } 37491da177e4SLinus Torvalds 3750a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 37515590ff0dSUlrich Drepper { 37525590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 37535590ff0dSUlrich Drepper } 37545590ff0dSUlrich Drepper 37551da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 37561da177e4SLinus Torvalds { 37571da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 37581da177e4SLinus Torvalds 37591da177e4SLinus Torvalds if (error) 37601da177e4SLinus Torvalds return error; 37611da177e4SLinus Torvalds 3762acfa4380SAl Viro if (!dir->i_op->rmdir) 37631da177e4SLinus Torvalds return -EPERM; 37641da177e4SLinus Torvalds 37651d2ef590SAl Viro dget(dentry); 37665955102cSAl Viro inode_lock(dentry->d_inode); 3767912dbc15SSage Weil 37681da177e4SLinus Torvalds error = -EBUSY; 37697af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3770912dbc15SSage Weil goto out; 3771912dbc15SSage Weil 37721da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3773912dbc15SSage Weil if (error) 3774912dbc15SSage Weil goto out; 3775912dbc15SSage Weil 37763cebde24SSage Weil shrink_dcache_parent(dentry); 37771da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3778912dbc15SSage Weil if (error) 3779912dbc15SSage Weil goto out; 3780912dbc15SSage Weil 37811da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3782d83c49f3SAl Viro dont_mount(dentry); 37838ed936b5SEric W. Biederman detach_mounts(dentry); 37841da177e4SLinus Torvalds 3785912dbc15SSage Weil out: 37865955102cSAl Viro inode_unlock(dentry->d_inode); 37871d2ef590SAl Viro dput(dentry); 3788912dbc15SSage Weil if (!error) 3789912dbc15SSage Weil d_delete(dentry); 37901da177e4SLinus Torvalds return error; 37911da177e4SLinus Torvalds } 37924d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 37931da177e4SLinus Torvalds 37945590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 37951da177e4SLinus Torvalds { 37961da177e4SLinus Torvalds int error = 0; 379791a27b2aSJeff Layton struct filename *name; 37981da177e4SLinus Torvalds struct dentry *dentry; 3799f5beed75SAl Viro struct path path; 3800f5beed75SAl Viro struct qstr last; 3801f5beed75SAl Viro int type; 3802c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3803c6ee9206SJeff Layton retry: 3804c1d4dd27SAl Viro name = filename_parentat(dfd, getname(pathname), lookup_flags, 3805c1d4dd27SAl Viro &path, &last, &type); 380691a27b2aSJeff Layton if (IS_ERR(name)) 380791a27b2aSJeff Layton return PTR_ERR(name); 38081da177e4SLinus Torvalds 3809f5beed75SAl Viro switch (type) { 38101da177e4SLinus Torvalds case LAST_DOTDOT: 38111da177e4SLinus Torvalds error = -ENOTEMPTY; 38121da177e4SLinus Torvalds goto exit1; 38131da177e4SLinus Torvalds case LAST_DOT: 38141da177e4SLinus Torvalds error = -EINVAL; 38151da177e4SLinus Torvalds goto exit1; 38161da177e4SLinus Torvalds case LAST_ROOT: 38171da177e4SLinus Torvalds error = -EBUSY; 38181da177e4SLinus Torvalds goto exit1; 38191da177e4SLinus Torvalds } 38200612d9fbSOGAWA Hirofumi 3821f5beed75SAl Viro error = mnt_want_write(path.mnt); 3822c30dabfeSJan Kara if (error) 3823c30dabfeSJan Kara goto exit1; 38240612d9fbSOGAWA Hirofumi 38255955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3826f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38271da177e4SLinus Torvalds error = PTR_ERR(dentry); 38286902d925SDave Hansen if (IS_ERR(dentry)) 38296902d925SDave Hansen goto exit2; 3830e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3831e6bc45d6STheodore Ts'o error = -ENOENT; 3832e6bc45d6STheodore Ts'o goto exit3; 3833e6bc45d6STheodore Ts'o } 3834f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3835be6d3e56SKentaro Takeda if (error) 3836c30dabfeSJan Kara goto exit3; 3837f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 38380622753bSDave Hansen exit3: 38391da177e4SLinus Torvalds dput(dentry); 38406902d925SDave Hansen exit2: 38415955102cSAl Viro inode_unlock(path.dentry->d_inode); 3842f5beed75SAl Viro mnt_drop_write(path.mnt); 38431da177e4SLinus Torvalds exit1: 3844f5beed75SAl Viro path_put(&path); 38451da177e4SLinus Torvalds putname(name); 3846c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3847c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3848c6ee9206SJeff Layton goto retry; 3849c6ee9206SJeff Layton } 38501da177e4SLinus Torvalds return error; 38511da177e4SLinus Torvalds } 38521da177e4SLinus Torvalds 38533cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 38545590ff0dSUlrich Drepper { 38555590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 38565590ff0dSUlrich Drepper } 38575590ff0dSUlrich Drepper 3858b21996e3SJ. Bruce Fields /** 3859b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3860b21996e3SJ. Bruce Fields * @dir: parent directory 3861b21996e3SJ. Bruce Fields * @dentry: victim 3862b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3863b21996e3SJ. Bruce Fields * 3864b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3865b21996e3SJ. Bruce Fields * 3866b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3867b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3868b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3869b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3870b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3871b21996e3SJ. Bruce Fields * 3872b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3873b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3874b21996e3SJ. Bruce Fields * to be NFS exported. 3875b21996e3SJ. Bruce Fields */ 3876b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 38771da177e4SLinus Torvalds { 38789accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 38791da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 38801da177e4SLinus Torvalds 38811da177e4SLinus Torvalds if (error) 38821da177e4SLinus Torvalds return error; 38831da177e4SLinus Torvalds 3884acfa4380SAl Viro if (!dir->i_op->unlink) 38851da177e4SLinus Torvalds return -EPERM; 38861da177e4SLinus Torvalds 38875955102cSAl Viro inode_lock(target); 38888ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 38891da177e4SLinus Torvalds error = -EBUSY; 38901da177e4SLinus Torvalds else { 38911da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3892bec1052eSAl Viro if (!error) { 38935a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 38945a14696cSJ. Bruce Fields if (error) 3895b21996e3SJ. Bruce Fields goto out; 38961da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 38978ed936b5SEric W. Biederman if (!error) { 3898d83c49f3SAl Viro dont_mount(dentry); 38998ed936b5SEric W. Biederman detach_mounts(dentry); 39008ed936b5SEric W. Biederman } 3901bec1052eSAl Viro } 39021da177e4SLinus Torvalds } 3903b21996e3SJ. Bruce Fields out: 39045955102cSAl Viro inode_unlock(target); 39051da177e4SLinus Torvalds 39061da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 39071da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 39089accbb97SJ. Bruce Fields fsnotify_link_count(target); 39091da177e4SLinus Torvalds d_delete(dentry); 39101da177e4SLinus Torvalds } 39110eeca283SRobert Love 39121da177e4SLinus Torvalds return error; 39131da177e4SLinus Torvalds } 39144d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 39151da177e4SLinus Torvalds 39161da177e4SLinus Torvalds /* 39171da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 39181b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 39191da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 39201da177e4SLinus Torvalds * while waiting on the I/O. 39211da177e4SLinus Torvalds */ 39225590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 39231da177e4SLinus Torvalds { 39242ad94ae6SAl Viro int error; 392591a27b2aSJeff Layton struct filename *name; 39261da177e4SLinus Torvalds struct dentry *dentry; 3927f5beed75SAl Viro struct path path; 3928f5beed75SAl Viro struct qstr last; 3929f5beed75SAl Viro int type; 39301da177e4SLinus Torvalds struct inode *inode = NULL; 3931b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 39325d18f813SJeff Layton unsigned int lookup_flags = 0; 39335d18f813SJeff Layton retry: 3934c1d4dd27SAl Viro name = filename_parentat(dfd, getname(pathname), lookup_flags, 3935c1d4dd27SAl Viro &path, &last, &type); 393691a27b2aSJeff Layton if (IS_ERR(name)) 393791a27b2aSJeff Layton return PTR_ERR(name); 39382ad94ae6SAl Viro 39391da177e4SLinus Torvalds error = -EISDIR; 3940f5beed75SAl Viro if (type != LAST_NORM) 39411da177e4SLinus Torvalds goto exit1; 39420612d9fbSOGAWA Hirofumi 3943f5beed75SAl Viro error = mnt_want_write(path.mnt); 3944c30dabfeSJan Kara if (error) 3945c30dabfeSJan Kara goto exit1; 3946b21996e3SJ. Bruce Fields retry_deleg: 39475955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3948f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 39491da177e4SLinus Torvalds error = PTR_ERR(dentry); 39501da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 39511da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3952f5beed75SAl Viro if (last.name[last.len]) 395350338b88STörök Edwin goto slashes; 39541da177e4SLinus Torvalds inode = dentry->d_inode; 3955b18825a7SDavid Howells if (d_is_negative(dentry)) 3956e6bc45d6STheodore Ts'o goto slashes; 39577de9c6eeSAl Viro ihold(inode); 3958f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3959be6d3e56SKentaro Takeda if (error) 3960c30dabfeSJan Kara goto exit2; 3961f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 39621da177e4SLinus Torvalds exit2: 39631da177e4SLinus Torvalds dput(dentry); 39641da177e4SLinus Torvalds } 39655955102cSAl Viro inode_unlock(path.dentry->d_inode); 39661da177e4SLinus Torvalds if (inode) 39671da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3968b21996e3SJ. Bruce Fields inode = NULL; 3969b21996e3SJ. Bruce Fields if (delegated_inode) { 39705a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3971b21996e3SJ. Bruce Fields if (!error) 3972b21996e3SJ. Bruce Fields goto retry_deleg; 3973b21996e3SJ. Bruce Fields } 3974f5beed75SAl Viro mnt_drop_write(path.mnt); 39751da177e4SLinus Torvalds exit1: 3976f5beed75SAl Viro path_put(&path); 39771da177e4SLinus Torvalds putname(name); 39785d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 39795d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 39805d18f813SJeff Layton inode = NULL; 39815d18f813SJeff Layton goto retry; 39825d18f813SJeff Layton } 39831da177e4SLinus Torvalds return error; 39841da177e4SLinus Torvalds 39851da177e4SLinus Torvalds slashes: 3986b18825a7SDavid Howells if (d_is_negative(dentry)) 3987b18825a7SDavid Howells error = -ENOENT; 398844b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3989b18825a7SDavid Howells error = -EISDIR; 3990b18825a7SDavid Howells else 3991b18825a7SDavid Howells error = -ENOTDIR; 39921da177e4SLinus Torvalds goto exit2; 39931da177e4SLinus Torvalds } 39941da177e4SLinus Torvalds 39952e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 39965590ff0dSUlrich Drepper { 39975590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 39985590ff0dSUlrich Drepper return -EINVAL; 39995590ff0dSUlrich Drepper 40005590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 40015590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 40025590ff0dSUlrich Drepper 40035590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 40045590ff0dSUlrich Drepper } 40055590ff0dSUlrich Drepper 40063480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 40075590ff0dSUlrich Drepper { 40085590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 40095590ff0dSUlrich Drepper } 40105590ff0dSUlrich Drepper 4011db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 40121da177e4SLinus Torvalds { 4013a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 40141da177e4SLinus Torvalds 40151da177e4SLinus Torvalds if (error) 40161da177e4SLinus Torvalds return error; 40171da177e4SLinus Torvalds 4018acfa4380SAl Viro if (!dir->i_op->symlink) 40191da177e4SLinus Torvalds return -EPERM; 40201da177e4SLinus Torvalds 40211da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 40221da177e4SLinus Torvalds if (error) 40231da177e4SLinus Torvalds return error; 40241da177e4SLinus Torvalds 40251da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 4026a74574aaSStephen Smalley if (!error) 4027f38aa942SAmy Griffis fsnotify_create(dir, dentry); 40281da177e4SLinus Torvalds return error; 40291da177e4SLinus Torvalds } 40304d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 40311da177e4SLinus Torvalds 40322e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 40332e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 40341da177e4SLinus Torvalds { 40352ad94ae6SAl Viro int error; 403691a27b2aSJeff Layton struct filename *from; 40376902d925SDave Hansen struct dentry *dentry; 4038dae6ad8fSAl Viro struct path path; 4039f46d3567SJeff Layton unsigned int lookup_flags = 0; 40401da177e4SLinus Torvalds 40411da177e4SLinus Torvalds from = getname(oldname); 40421da177e4SLinus Torvalds if (IS_ERR(from)) 40431da177e4SLinus Torvalds return PTR_ERR(from); 4044f46d3567SJeff Layton retry: 4045f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 40461da177e4SLinus Torvalds error = PTR_ERR(dentry); 40476902d925SDave Hansen if (IS_ERR(dentry)) 4048dae6ad8fSAl Viro goto out_putname; 40496902d925SDave Hansen 405091a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4051a8104a9fSAl Viro if (!error) 405291a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4053921a1650SAl Viro done_path_create(&path, dentry); 4054f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4055f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4056f46d3567SJeff Layton goto retry; 4057f46d3567SJeff Layton } 40586902d925SDave Hansen out_putname: 40591da177e4SLinus Torvalds putname(from); 40601da177e4SLinus Torvalds return error; 40611da177e4SLinus Torvalds } 40621da177e4SLinus Torvalds 40633480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 40645590ff0dSUlrich Drepper { 40655590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 40665590ff0dSUlrich Drepper } 40675590ff0dSUlrich Drepper 4068146a8595SJ. Bruce Fields /** 4069146a8595SJ. Bruce Fields * vfs_link - create a new link 4070146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4071146a8595SJ. Bruce Fields * @dir: new parent 4072146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4073146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4074146a8595SJ. Bruce Fields * 4075146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4076146a8595SJ. Bruce Fields * 4077146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4078146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4079146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4080146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4081146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4082146a8595SJ. Bruce Fields * 4083146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4084146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4085146a8595SJ. Bruce Fields * to be NFS exported. 4086146a8595SJ. Bruce Fields */ 4087146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 40881da177e4SLinus Torvalds { 40891da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 40908de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 40911da177e4SLinus Torvalds int error; 40921da177e4SLinus Torvalds 40931da177e4SLinus Torvalds if (!inode) 40941da177e4SLinus Torvalds return -ENOENT; 40951da177e4SLinus Torvalds 4096a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 40971da177e4SLinus Torvalds if (error) 40981da177e4SLinus Torvalds return error; 40991da177e4SLinus Torvalds 41001da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 41011da177e4SLinus Torvalds return -EXDEV; 41021da177e4SLinus Torvalds 41031da177e4SLinus Torvalds /* 41041da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 41051da177e4SLinus Torvalds */ 41061da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 41071da177e4SLinus Torvalds return -EPERM; 41080bd23d09SEric W. Biederman /* 41090bd23d09SEric W. Biederman * Updating the link count will likely cause i_uid and i_gid to 41100bd23d09SEric W. Biederman * be writen back improperly if their true value is unknown to 41110bd23d09SEric W. Biederman * the vfs. 41120bd23d09SEric W. Biederman */ 41130bd23d09SEric W. Biederman if (HAS_UNMAPPED_ID(inode)) 41140bd23d09SEric W. Biederman return -EPERM; 4115acfa4380SAl Viro if (!dir->i_op->link) 41161da177e4SLinus Torvalds return -EPERM; 41177e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 41181da177e4SLinus Torvalds return -EPERM; 41191da177e4SLinus Torvalds 41201da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 41211da177e4SLinus Torvalds if (error) 41221da177e4SLinus Torvalds return error; 41231da177e4SLinus Torvalds 41245955102cSAl Viro inode_lock(inode); 4125aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4126f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4127aae8a97dSAneesh Kumar K.V error = -ENOENT; 41288de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 41298de52778SAl Viro error = -EMLINK; 4130146a8595SJ. Bruce Fields else { 4131146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4132146a8595SJ. Bruce Fields if (!error) 41331da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4134146a8595SJ. Bruce Fields } 4135f4e0c30cSAl Viro 4136f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4137f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4138f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4139f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4140f4e0c30cSAl Viro } 41415955102cSAl Viro inode_unlock(inode); 4142e31e14ecSStephen Smalley if (!error) 41437e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 41441da177e4SLinus Torvalds return error; 41451da177e4SLinus Torvalds } 41464d359507SAl Viro EXPORT_SYMBOL(vfs_link); 41471da177e4SLinus Torvalds 41481da177e4SLinus Torvalds /* 41491da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 41501da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 41511da177e4SLinus Torvalds * newname. --KAB 41521da177e4SLinus Torvalds * 41531da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 41541da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 41551da177e4SLinus Torvalds * and other special files. --ADM 41561da177e4SLinus Torvalds */ 41572e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 41582e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 41591da177e4SLinus Torvalds { 41601da177e4SLinus Torvalds struct dentry *new_dentry; 4161dae6ad8fSAl Viro struct path old_path, new_path; 4162146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 416311a7b371SAneesh Kumar K.V int how = 0; 41641da177e4SLinus Torvalds int error; 41651da177e4SLinus Torvalds 416611a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4167c04030e1SUlrich Drepper return -EINVAL; 416811a7b371SAneesh Kumar K.V /* 4169f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4170f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4171f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 417211a7b371SAneesh Kumar K.V */ 4173f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4174f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4175f0cc6ffbSLinus Torvalds return -ENOENT; 417611a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4177f0cc6ffbSLinus Torvalds } 4178c04030e1SUlrich Drepper 417911a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 418011a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4181442e31caSJeff Layton retry: 418211a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 41831da177e4SLinus Torvalds if (error) 41842ad94ae6SAl Viro return error; 41852ad94ae6SAl Viro 4186442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4187442e31caSJeff Layton (how & LOOKUP_REVAL)); 41881da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 41896902d925SDave Hansen if (IS_ERR(new_dentry)) 4190dae6ad8fSAl Viro goto out; 4191dae6ad8fSAl Viro 4192dae6ad8fSAl Viro error = -EXDEV; 4193dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4194dae6ad8fSAl Viro goto out_dput; 4195800179c9SKees Cook error = may_linkat(&old_path); 4196800179c9SKees Cook if (unlikely(error)) 4197800179c9SKees Cook goto out_dput; 4198dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4199be6d3e56SKentaro Takeda if (error) 4200a8104a9fSAl Viro goto out_dput; 4201146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 420275c3f29dSDave Hansen out_dput: 4203921a1650SAl Viro done_path_create(&new_path, new_dentry); 4204146a8595SJ. Bruce Fields if (delegated_inode) { 4205146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4206d22e6338SOleg Drokin if (!error) { 4207d22e6338SOleg Drokin path_put(&old_path); 4208146a8595SJ. Bruce Fields goto retry; 4209146a8595SJ. Bruce Fields } 4210d22e6338SOleg Drokin } 4211442e31caSJeff Layton if (retry_estale(error, how)) { 4212d22e6338SOleg Drokin path_put(&old_path); 4213442e31caSJeff Layton how |= LOOKUP_REVAL; 4214442e31caSJeff Layton goto retry; 4215442e31caSJeff Layton } 42161da177e4SLinus Torvalds out: 42172d8f3038SAl Viro path_put(&old_path); 42181da177e4SLinus Torvalds 42191da177e4SLinus Torvalds return error; 42201da177e4SLinus Torvalds } 42211da177e4SLinus Torvalds 42223480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 42235590ff0dSUlrich Drepper { 4224c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 42255590ff0dSUlrich Drepper } 42265590ff0dSUlrich Drepper 4227bc27027aSMiklos Szeredi /** 4228bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4229bc27027aSMiklos Szeredi * @old_dir: parent of source 4230bc27027aSMiklos Szeredi * @old_dentry: source 4231bc27027aSMiklos Szeredi * @new_dir: parent of destination 4232bc27027aSMiklos Szeredi * @new_dentry: destination 4233bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4234520c8b16SMiklos Szeredi * @flags: rename flags 4235bc27027aSMiklos Szeredi * 4236bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4237bc27027aSMiklos Szeredi * 4238bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4239bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4240bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4241bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4242bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4243bc27027aSMiklos Szeredi * so. 4244bc27027aSMiklos Szeredi * 4245bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4246bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4247bc27027aSMiklos Szeredi * to be NFS exported. 4248bc27027aSMiklos Szeredi * 42491da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 42501da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 42511da177e4SLinus Torvalds * Problems: 4252d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 42531da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 42541da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4255a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 42561da177e4SLinus Torvalds * story. 42576cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 42586cedba89SJ. Bruce Fields * and source (if it is not a directory). 42591b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 42601da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 42611da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4262a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 42631da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 42641da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 42651da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4266a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 42671da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 42681da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 42691da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4270e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 42711b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 42721da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4273c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 42741da177e4SLinus Torvalds * locking]. 42751da177e4SLinus Torvalds */ 42761da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 42778e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4278520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 42791da177e4SLinus Torvalds { 42801da177e4SLinus Torvalds int error; 4281bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 428259b0df21SEric Paris const unsigned char *old_name; 4283bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4284bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4285da1ce067SMiklos Szeredi bool new_is_dir = false; 4286da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 42871da177e4SLinus Torvalds 42888d3e2936SMiklos Szeredi if (source == target) 42891da177e4SLinus Torvalds return 0; 42901da177e4SLinus Torvalds 42911da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 42921da177e4SLinus Torvalds if (error) 42931da177e4SLinus Torvalds return error; 42941da177e4SLinus Torvalds 4295da1ce067SMiklos Szeredi if (!target) { 4296a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4297da1ce067SMiklos Szeredi } else { 4298da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4299da1ce067SMiklos Szeredi 4300da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43011da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4302da1ce067SMiklos Szeredi else 4303da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4304da1ce067SMiklos Szeredi } 43051da177e4SLinus Torvalds if (error) 43061da177e4SLinus Torvalds return error; 43071da177e4SLinus Torvalds 43082773bf00SMiklos Szeredi if (!old_dir->i_op->rename) 43091da177e4SLinus Torvalds return -EPERM; 43101da177e4SLinus Torvalds 4311bc27027aSMiklos Szeredi /* 4312bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4313bc27027aSMiklos Szeredi * we'll need to flip '..'. 4314bc27027aSMiklos Szeredi */ 4315da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4316da1ce067SMiklos Szeredi if (is_dir) { 4317bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4318bc27027aSMiklos Szeredi if (error) 4319bc27027aSMiklos Szeredi return error; 4320bc27027aSMiklos Szeredi } 4321da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4322da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4323da1ce067SMiklos Szeredi if (error) 4324da1ce067SMiklos Szeredi return error; 4325da1ce067SMiklos Szeredi } 4326da1ce067SMiklos Szeredi } 43270eeca283SRobert Love 43280b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 43290b3974ebSMiklos Szeredi flags); 4330bc27027aSMiklos Szeredi if (error) 4331bc27027aSMiklos Szeredi return error; 4332bc27027aSMiklos Szeredi 4333bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4334bc27027aSMiklos Szeredi dget(new_dentry); 4335da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4336bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4337bc27027aSMiklos Szeredi else if (target) 43385955102cSAl Viro inode_lock(target); 4339bc27027aSMiklos Szeredi 4340bc27027aSMiklos Szeredi error = -EBUSY; 43417af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4342bc27027aSMiklos Szeredi goto out; 4343bc27027aSMiklos Szeredi 4344da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4345bc27027aSMiklos Szeredi error = -EMLINK; 4346da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4347bc27027aSMiklos Szeredi goto out; 4348da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4349da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4350da1ce067SMiklos Szeredi goto out; 4351da1ce067SMiklos Szeredi } 4352da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4353bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4354da1ce067SMiklos Szeredi if (!is_dir) { 4355bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4356bc27027aSMiklos Szeredi if (error) 4357bc27027aSMiklos Szeredi goto out; 4358da1ce067SMiklos Szeredi } 4359da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4360bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4361bc27027aSMiklos Szeredi if (error) 4362bc27027aSMiklos Szeredi goto out; 4363bc27027aSMiklos Szeredi } 4364520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4365520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4366bc27027aSMiklos Szeredi if (error) 4367bc27027aSMiklos Szeredi goto out; 4368bc27027aSMiklos Szeredi 4369da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 43701da177e4SLinus Torvalds if (is_dir) 4371bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4372bc27027aSMiklos Szeredi dont_mount(new_dentry); 43738ed936b5SEric W. Biederman detach_mounts(new_dentry); 4374bc27027aSMiklos Szeredi } 4375da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4376da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4377bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4378da1ce067SMiklos Szeredi else 4379da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4380da1ce067SMiklos Szeredi } 4381bc27027aSMiklos Szeredi out: 4382da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4383bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4384bc27027aSMiklos Szeredi else if (target) 43855955102cSAl Viro inode_unlock(target); 4386bc27027aSMiklos Szeredi dput(new_dentry); 4387da1ce067SMiklos Szeredi if (!error) { 4388123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4389da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4390da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4391da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4392da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4393da1ce067SMiklos Szeredi } 4394da1ce067SMiklos Szeredi } 43950eeca283SRobert Love fsnotify_oldname_free(old_name); 43960eeca283SRobert Love 43971da177e4SLinus Torvalds return error; 43981da177e4SLinus Torvalds } 43994d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 44001da177e4SLinus Torvalds 4401520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4402520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 44031da177e4SLinus Torvalds { 44041da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 44051da177e4SLinus Torvalds struct dentry *trap; 4406f5beed75SAl Viro struct path old_path, new_path; 4407f5beed75SAl Viro struct qstr old_last, new_last; 4408f5beed75SAl Viro int old_type, new_type; 44098e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 441091a27b2aSJeff Layton struct filename *from; 441191a27b2aSJeff Layton struct filename *to; 4412f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4413c6a94284SJeff Layton bool should_retry = false; 44142ad94ae6SAl Viro int error; 4415520c8b16SMiklos Szeredi 44160d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4417da1ce067SMiklos Szeredi return -EINVAL; 4418da1ce067SMiklos Szeredi 44190d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 44200d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4421520c8b16SMiklos Szeredi return -EINVAL; 4422520c8b16SMiklos Szeredi 44230d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 44240d7a8555SMiklos Szeredi return -EPERM; 44250d7a8555SMiklos Szeredi 4426f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4427f5beed75SAl Viro target_flags = 0; 4428f5beed75SAl Viro 4429c6a94284SJeff Layton retry: 4430c1d4dd27SAl Viro from = filename_parentat(olddfd, getname(oldname), lookup_flags, 4431c1d4dd27SAl Viro &old_path, &old_last, &old_type); 443291a27b2aSJeff Layton if (IS_ERR(from)) { 443391a27b2aSJeff Layton error = PTR_ERR(from); 44341da177e4SLinus Torvalds goto exit; 443591a27b2aSJeff Layton } 44361da177e4SLinus Torvalds 4437c1d4dd27SAl Viro to = filename_parentat(newdfd, getname(newname), lookup_flags, 4438c1d4dd27SAl Viro &new_path, &new_last, &new_type); 443991a27b2aSJeff Layton if (IS_ERR(to)) { 444091a27b2aSJeff Layton error = PTR_ERR(to); 44411da177e4SLinus Torvalds goto exit1; 444291a27b2aSJeff Layton } 44431da177e4SLinus Torvalds 44441da177e4SLinus Torvalds error = -EXDEV; 4445f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 44461da177e4SLinus Torvalds goto exit2; 44471da177e4SLinus Torvalds 44481da177e4SLinus Torvalds error = -EBUSY; 4449f5beed75SAl Viro if (old_type != LAST_NORM) 44501da177e4SLinus Torvalds goto exit2; 44511da177e4SLinus Torvalds 44520a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 44530a7c3937SMiklos Szeredi error = -EEXIST; 4454f5beed75SAl Viro if (new_type != LAST_NORM) 44551da177e4SLinus Torvalds goto exit2; 44561da177e4SLinus Torvalds 4457f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4458c30dabfeSJan Kara if (error) 4459c30dabfeSJan Kara goto exit2; 4460c30dabfeSJan Kara 44618e6d782cSJ. Bruce Fields retry_deleg: 4462f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 44631da177e4SLinus Torvalds 4464f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 44651da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 44661da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 44671da177e4SLinus Torvalds goto exit3; 44681da177e4SLinus Torvalds /* source must exist */ 44691da177e4SLinus Torvalds error = -ENOENT; 4470b18825a7SDavid Howells if (d_is_negative(old_dentry)) 44711da177e4SLinus Torvalds goto exit4; 4472f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 44731da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 44741da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 44751da177e4SLinus Torvalds goto exit4; 44760a7c3937SMiklos Szeredi error = -EEXIST; 44770a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 44780a7c3937SMiklos Szeredi goto exit5; 4479da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4480da1ce067SMiklos Szeredi error = -ENOENT; 4481da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4482da1ce067SMiklos Szeredi goto exit5; 4483da1ce067SMiklos Szeredi 4484da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4485da1ce067SMiklos Szeredi error = -ENOTDIR; 4486f5beed75SAl Viro if (new_last.name[new_last.len]) 4487da1ce067SMiklos Szeredi goto exit5; 4488da1ce067SMiklos Szeredi } 4489da1ce067SMiklos Szeredi } 44900a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 44910a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 44920a7c3937SMiklos Szeredi error = -ENOTDIR; 4493f5beed75SAl Viro if (old_last.name[old_last.len]) 44940a7c3937SMiklos Szeredi goto exit5; 4495f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 44960a7c3937SMiklos Szeredi goto exit5; 44970a7c3937SMiklos Szeredi } 44980a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 44990a7c3937SMiklos Szeredi error = -EINVAL; 45000a7c3937SMiklos Szeredi if (old_dentry == trap) 45010a7c3937SMiklos Szeredi goto exit5; 45021da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4503da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 45041da177e4SLinus Torvalds error = -ENOTEMPTY; 45051da177e4SLinus Torvalds if (new_dentry == trap) 45061da177e4SLinus Torvalds goto exit5; 45071da177e4SLinus Torvalds 4508f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4509f5beed75SAl Viro &new_path, new_dentry, flags); 4510be6d3e56SKentaro Takeda if (error) 4511c30dabfeSJan Kara goto exit5; 4512f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4513f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4514520c8b16SMiklos Szeredi &delegated_inode, flags); 45151da177e4SLinus Torvalds exit5: 45161da177e4SLinus Torvalds dput(new_dentry); 45171da177e4SLinus Torvalds exit4: 45181da177e4SLinus Torvalds dput(old_dentry); 45191da177e4SLinus Torvalds exit3: 4520f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 45218e6d782cSJ. Bruce Fields if (delegated_inode) { 45228e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 45238e6d782cSJ. Bruce Fields if (!error) 45248e6d782cSJ. Bruce Fields goto retry_deleg; 45258e6d782cSJ. Bruce Fields } 4526f5beed75SAl Viro mnt_drop_write(old_path.mnt); 45271da177e4SLinus Torvalds exit2: 4528c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4529c6a94284SJeff Layton should_retry = true; 4530f5beed75SAl Viro path_put(&new_path); 45312ad94ae6SAl Viro putname(to); 45321da177e4SLinus Torvalds exit1: 4533f5beed75SAl Viro path_put(&old_path); 45341da177e4SLinus Torvalds putname(from); 4535c6a94284SJeff Layton if (should_retry) { 4536c6a94284SJeff Layton should_retry = false; 4537c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4538c6a94284SJeff Layton goto retry; 4539c6a94284SJeff Layton } 45402ad94ae6SAl Viro exit: 45411da177e4SLinus Torvalds return error; 45421da177e4SLinus Torvalds } 45431da177e4SLinus Torvalds 4544520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4545520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4546520c8b16SMiklos Szeredi { 4547520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4548520c8b16SMiklos Szeredi } 4549520c8b16SMiklos Szeredi 4550a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 45515590ff0dSUlrich Drepper { 4552520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 45535590ff0dSUlrich Drepper } 45545590ff0dSUlrich Drepper 4555787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4556787fb6bcSMiklos Szeredi { 4557787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4558787fb6bcSMiklos Szeredi if (error) 4559787fb6bcSMiklos Szeredi return error; 4560787fb6bcSMiklos Szeredi 4561787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4562787fb6bcSMiklos Szeredi return -EPERM; 4563787fb6bcSMiklos Szeredi 4564787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4565787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4566787fb6bcSMiklos Szeredi } 4567787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4568787fb6bcSMiklos Szeredi 45695d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 45701da177e4SLinus Torvalds { 45715d826c84SAl Viro int len = PTR_ERR(link); 45721da177e4SLinus Torvalds if (IS_ERR(link)) 45731da177e4SLinus Torvalds goto out; 45741da177e4SLinus Torvalds 45751da177e4SLinus Torvalds len = strlen(link); 45761da177e4SLinus Torvalds if (len > (unsigned) buflen) 45771da177e4SLinus Torvalds len = buflen; 45781da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 45791da177e4SLinus Torvalds len = -EFAULT; 45801da177e4SLinus Torvalds out: 45811da177e4SLinus Torvalds return len; 45821da177e4SLinus Torvalds } 45831da177e4SLinus Torvalds 45841da177e4SLinus Torvalds /* 45851da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 45866b255391SAl Viro * have ->get_link() not calling nd_jump_link(). Using (or not using) it 45876b255391SAl Viro * for any given inode is up to filesystem. 45881da177e4SLinus Torvalds */ 4589d16744ecSMiklos Szeredi static int generic_readlink(struct dentry *dentry, char __user *buffer, 4590d16744ecSMiklos Szeredi int buflen) 45911da177e4SLinus Torvalds { 4592fceef393SAl Viro DEFINE_DELAYED_CALL(done); 45935f2c4179SAl Viro struct inode *inode = d_inode(dentry); 45945f2c4179SAl Viro const char *link = inode->i_link; 4595694a1764SMarcin Slusarz int res; 4596cc314eefSLinus Torvalds 4597d4dee48bSAl Viro if (!link) { 4598fceef393SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4599680baacbSAl Viro if (IS_ERR(link)) 4600680baacbSAl Viro return PTR_ERR(link); 4601d4dee48bSAl Viro } 4602680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 4603fceef393SAl Viro do_delayed_call(&done); 4604694a1764SMarcin Slusarz return res; 46051da177e4SLinus Torvalds } 46061da177e4SLinus Torvalds 4607d60874cdSMiklos Szeredi /** 4608fd4a0edfSMiklos Szeredi * vfs_readlink - copy symlink body into userspace buffer 4609fd4a0edfSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4610fd4a0edfSMiklos Szeredi * @buffer: user memory pointer 4611fd4a0edfSMiklos Szeredi * @buflen: size of buffer 4612fd4a0edfSMiklos Szeredi * 4613fd4a0edfSMiklos Szeredi * Does not touch atime. That's up to the caller if necessary 4614fd4a0edfSMiklos Szeredi * 4615fd4a0edfSMiklos Szeredi * Does not call security hook. 4616fd4a0edfSMiklos Szeredi */ 4617fd4a0edfSMiklos Szeredi int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4618fd4a0edfSMiklos Szeredi { 4619fd4a0edfSMiklos Szeredi struct inode *inode = d_inode(dentry); 4620fd4a0edfSMiklos Szeredi 462176fca90eSMiklos Szeredi if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) { 462276fca90eSMiklos Szeredi if (unlikely(inode->i_op->readlink)) 462376fca90eSMiklos Szeredi return inode->i_op->readlink(dentry, buffer, buflen); 462476fca90eSMiklos Szeredi 462576fca90eSMiklos Szeredi if (!d_is_symlink(dentry)) 4626fd4a0edfSMiklos Szeredi return -EINVAL; 4627fd4a0edfSMiklos Szeredi 462876fca90eSMiklos Szeredi spin_lock(&inode->i_lock); 462976fca90eSMiklos Szeredi inode->i_opflags |= IOP_DEFAULT_READLINK; 463076fca90eSMiklos Szeredi spin_unlock(&inode->i_lock); 463176fca90eSMiklos Szeredi } 463276fca90eSMiklos Szeredi 463376fca90eSMiklos Szeredi return generic_readlink(dentry, buffer, buflen); 4634fd4a0edfSMiklos Szeredi } 4635fd4a0edfSMiklos Szeredi EXPORT_SYMBOL(vfs_readlink); 46361da177e4SLinus Torvalds 4637d60874cdSMiklos Szeredi /** 4638d60874cdSMiklos Szeredi * vfs_get_link - get symlink body 4639d60874cdSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4640d60874cdSMiklos Szeredi * @done: caller needs to free returned data with this 4641d60874cdSMiklos Szeredi * 4642d60874cdSMiklos Szeredi * Calls security hook and i_op->get_link() on the supplied inode. 4643d60874cdSMiklos Szeredi * 4644d60874cdSMiklos Szeredi * It does not touch atime. That's up to the caller if necessary. 4645d60874cdSMiklos Szeredi * 4646d60874cdSMiklos Szeredi * Does not work on "special" symlinks like /proc/$$/fd/N 4647d60874cdSMiklos Szeredi */ 4648d60874cdSMiklos Szeredi const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done) 4649d60874cdSMiklos Szeredi { 4650d60874cdSMiklos Szeredi const char *res = ERR_PTR(-EINVAL); 4651d60874cdSMiklos Szeredi struct inode *inode = d_inode(dentry); 4652d60874cdSMiklos Szeredi 4653d60874cdSMiklos Szeredi if (d_is_symlink(dentry)) { 4654d60874cdSMiklos Szeredi res = ERR_PTR(security_inode_readlink(dentry)); 4655d60874cdSMiklos Szeredi if (!res) 4656d60874cdSMiklos Szeredi res = inode->i_op->get_link(dentry, inode, done); 4657d60874cdSMiklos Szeredi } 4658d60874cdSMiklos Szeredi return res; 4659d60874cdSMiklos Szeredi } 4660d60874cdSMiklos Szeredi EXPORT_SYMBOL(vfs_get_link); 4661d60874cdSMiklos Szeredi 46621da177e4SLinus Torvalds /* get the link contents into pagecache */ 46636b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4664fceef393SAl Viro struct delayed_call *callback) 46651da177e4SLinus Torvalds { 4666ebd09abbSDuane Griffin char *kaddr; 46671da177e4SLinus Torvalds struct page *page; 46686b255391SAl Viro struct address_space *mapping = inode->i_mapping; 46696b255391SAl Viro 4670d3883d4fSAl Viro if (!dentry) { 4671d3883d4fSAl Viro page = find_get_page(mapping, 0); 4672d3883d4fSAl Viro if (!page) 46736b255391SAl Viro return ERR_PTR(-ECHILD); 4674d3883d4fSAl Viro if (!PageUptodate(page)) { 4675d3883d4fSAl Viro put_page(page); 4676d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4677d3883d4fSAl Viro } 4678d3883d4fSAl Viro } else { 4679090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 46801da177e4SLinus Torvalds if (IS_ERR(page)) 46816fe6900eSNick Piggin return (char*)page; 4682d3883d4fSAl Viro } 4683fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 468421fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 468521fc61c7SAl Viro kaddr = page_address(page); 46866b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4687ebd09abbSDuane Griffin return kaddr; 46881da177e4SLinus Torvalds } 46891da177e4SLinus Torvalds 46906b255391SAl Viro EXPORT_SYMBOL(page_get_link); 46911da177e4SLinus Torvalds 4692fceef393SAl Viro void page_put_link(void *arg) 46931da177e4SLinus Torvalds { 4694fceef393SAl Viro put_page(arg); 46951da177e4SLinus Torvalds } 46964d359507SAl Viro EXPORT_SYMBOL(page_put_link); 46971da177e4SLinus Torvalds 4698aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4699aa80deabSAl Viro { 4700fceef393SAl Viro DEFINE_DELAYED_CALL(done); 47016b255391SAl Viro int res = readlink_copy(buffer, buflen, 47026b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4703fceef393SAl Viro &done)); 4704fceef393SAl Viro do_delayed_call(&done); 4705aa80deabSAl Viro return res; 4706aa80deabSAl Viro } 4707aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4708aa80deabSAl Viro 470954566b2cSNick Piggin /* 471054566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 471154566b2cSNick Piggin */ 471254566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 47131da177e4SLinus Torvalds { 47141da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 47150adb25d2SKirill Korotaev struct page *page; 4716afddba49SNick Piggin void *fsdata; 4717beb497abSDmitriy Monakhov int err; 471854566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 471954566b2cSNick Piggin if (nofs) 472054566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 47211da177e4SLinus Torvalds 47227e53cac4SNeilBrown retry: 4723afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 472454566b2cSNick Piggin flags, &page, &fsdata); 47251da177e4SLinus Torvalds if (err) 4726afddba49SNick Piggin goto fail; 4727afddba49SNick Piggin 472821fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4729afddba49SNick Piggin 4730afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4731afddba49SNick Piggin page, fsdata); 47321da177e4SLinus Torvalds if (err < 0) 47331da177e4SLinus Torvalds goto fail; 4734afddba49SNick Piggin if (err < len-1) 4735afddba49SNick Piggin goto retry; 4736afddba49SNick Piggin 47371da177e4SLinus Torvalds mark_inode_dirty(inode); 47381da177e4SLinus Torvalds return 0; 47391da177e4SLinus Torvalds fail: 47401da177e4SLinus Torvalds return err; 47411da177e4SLinus Torvalds } 47424d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 47431da177e4SLinus Torvalds 47440adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 47450adb25d2SKirill Korotaev { 47460adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4747c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 47480adb25d2SKirill Korotaev } 47494d359507SAl Viro EXPORT_SYMBOL(page_symlink); 47500adb25d2SKirill Korotaev 475192e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 47526b255391SAl Viro .get_link = page_get_link, 47531da177e4SLinus Torvalds }; 47541da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4755