11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namei.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Some corrections by tytso. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 121da177e4SLinus Torvalds * lookup logic. 131da177e4SLinus Torvalds */ 141da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 151da177e4SLinus Torvalds */ 161da177e4SLinus Torvalds 171da177e4SLinus Torvalds #include <linux/init.h> 18630d9c47SPaul Gortmaker #include <linux/export.h> 1944696908SDavid S. Miller #include <linux/kernel.h> 201da177e4SLinus Torvalds #include <linux/slab.h> 211da177e4SLinus Torvalds #include <linux/fs.h> 221da177e4SLinus Torvalds #include <linux/namei.h> 231da177e4SLinus Torvalds #include <linux/pagemap.h> 240eeca283SRobert Love #include <linux/fsnotify.h> 251da177e4SLinus Torvalds #include <linux/personality.h> 261da177e4SLinus Torvalds #include <linux/security.h> 276146f0d5SMimi Zohar #include <linux/ima.h> 281da177e4SLinus Torvalds #include <linux/syscalls.h> 291da177e4SLinus Torvalds #include <linux/mount.h> 301da177e4SLinus Torvalds #include <linux/audit.h> 3116f7e0feSRandy Dunlap #include <linux/capability.h> 32834f2a4aSTrond Myklebust #include <linux/file.h> 335590ff0dSUlrich Drepper #include <linux/fcntl.h> 3408ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 355ad4e53bSAl Viro #include <linux/fs_struct.h> 36e77819e5SLinus Torvalds #include <linux/posix_acl.h> 3799d263d4SLinus Torvalds #include <linux/hash.h> 382a18da7aSGeorge Spelvin #include <linux/bitops.h> 39aeaa4a79SEric W. Biederman #include <linux/init_task.h> 401da177e4SLinus Torvalds #include <asm/uaccess.h> 411da177e4SLinus Torvalds 42e81e3f4dSEric Paris #include "internal.h" 43c7105365SAl Viro #include "mount.h" 44e81e3f4dSEric Paris 451da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 461da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 471da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 481da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 491da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 501da177e4SLinus Torvalds * 511da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 521da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 531da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 541da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 551da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 561da177e4SLinus Torvalds * the special cases of the former code. 571da177e4SLinus Torvalds * 581da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 591da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 601da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 611da177e4SLinus Torvalds * 621da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 631da177e4SLinus Torvalds * resolution to correspond with current state of the code. 641da177e4SLinus Torvalds * 651da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 661da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 671da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 681da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 691da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 701da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 711da177e4SLinus Torvalds */ 721da177e4SLinus Torvalds 731da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 741da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 751da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 761da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 771da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 781da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7925985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 801da177e4SLinus Torvalds * 811da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 821da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 831da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 841da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 851da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 861da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 871da177e4SLinus Torvalds * and in the old Linux semantics. 881da177e4SLinus Torvalds */ 891da177e4SLinus Torvalds 901da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 911da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 921da177e4SLinus Torvalds * 931da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 941da177e4SLinus Torvalds */ 951da177e4SLinus Torvalds 961da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 971da177e4SLinus Torvalds * inside the path - always follow. 981da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 991da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 1001da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 1011da177e4SLinus Torvalds * otherwise - don't follow. 1021da177e4SLinus Torvalds * (applied in that order). 1031da177e4SLinus Torvalds * 1041da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1051da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1061da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1071da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1081da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1091da177e4SLinus Torvalds */ 1101da177e4SLinus Torvalds /* 1111da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 112a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1131da177e4SLinus Torvalds * any extra contention... 1141da177e4SLinus Torvalds */ 1151da177e4SLinus Torvalds 1161da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1171da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1181da177e4SLinus Torvalds * kernel data space before using them.. 1191da177e4SLinus Torvalds * 1201da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1211da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1221da177e4SLinus Torvalds */ 1237950e385SJeff Layton 124fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12591a27b2aSJeff Layton 12651f39a1fSDavid Drysdale struct filename * 12791a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12891a27b2aSJeff Layton { 12994b5d262SAl Viro struct filename *result; 1307950e385SJeff Layton char *kname; 13194b5d262SAl Viro int len; 1321da177e4SLinus Torvalds 1337ac86265SJeff Layton result = audit_reusename(filename); 1347ac86265SJeff Layton if (result) 1357ac86265SJeff Layton return result; 1367ac86265SJeff Layton 1377950e385SJeff Layton result = __getname(); 1383f9f0aa6SLinus Torvalds if (unlikely(!result)) 1394043cde8SEric Paris return ERR_PTR(-ENOMEM); 1401da177e4SLinus Torvalds 1417950e385SJeff Layton /* 1427950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1437950e385SJeff Layton * allocation 1447950e385SJeff Layton */ 145fd2f7cb5SAl Viro kname = (char *)result->iname; 14691a27b2aSJeff Layton result->name = kname; 1477950e385SJeff Layton 14894b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 14991a27b2aSJeff Layton if (unlikely(len < 0)) { 15094b5d262SAl Viro __putname(result); 15194b5d262SAl Viro return ERR_PTR(len); 15291a27b2aSJeff Layton } 1533f9f0aa6SLinus Torvalds 1547950e385SJeff Layton /* 1557950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1567950e385SJeff Layton * separate struct filename so we can dedicate the entire 1577950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1587950e385SJeff Layton * userland. 1597950e385SJeff Layton */ 16094b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 161fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1627950e385SJeff Layton kname = (char *)result; 1637950e385SJeff Layton 164fd2f7cb5SAl Viro /* 165fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 166fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 167fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 168fd2f7cb5SAl Viro */ 169fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 17094b5d262SAl Viro if (unlikely(!result)) { 17194b5d262SAl Viro __putname(kname); 17294b5d262SAl Viro return ERR_PTR(-ENOMEM); 1737950e385SJeff Layton } 1747950e385SJeff Layton result->name = kname; 17594b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17694b5d262SAl Viro if (unlikely(len < 0)) { 17794b5d262SAl Viro __putname(kname); 17894b5d262SAl Viro kfree(result); 17994b5d262SAl Viro return ERR_PTR(len); 18094b5d262SAl Viro } 18194b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18294b5d262SAl Viro __putname(kname); 18394b5d262SAl Viro kfree(result); 18494b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18594b5d262SAl Viro } 1867950e385SJeff Layton } 1877950e385SJeff Layton 18894b5d262SAl Viro result->refcnt = 1; 1893f9f0aa6SLinus Torvalds /* The empty path is special. */ 1903f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1913f9f0aa6SLinus Torvalds if (empty) 1921fa1e7f6SAndy Whitcroft *empty = 1; 19394b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19494b5d262SAl Viro putname(result); 19594b5d262SAl Viro return ERR_PTR(-ENOENT); 1961da177e4SLinus Torvalds } 19794b5d262SAl Viro } 1987950e385SJeff Layton 1997950e385SJeff Layton result->uptr = filename; 200c4ad8f98SLinus Torvalds result->aname = NULL; 2011da177e4SLinus Torvalds audit_getname(result); 2021da177e4SLinus Torvalds return result; 2033f9f0aa6SLinus Torvalds } 2043f9f0aa6SLinus Torvalds 20591a27b2aSJeff Layton struct filename * 20691a27b2aSJeff Layton getname(const char __user * filename) 207f52e0c11SAl Viro { 208f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 209f52e0c11SAl Viro } 210f52e0c11SAl Viro 211c4ad8f98SLinus Torvalds struct filename * 212c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 213c4ad8f98SLinus Torvalds { 214c4ad8f98SLinus Torvalds struct filename *result; 21508518549SPaul Moore int len = strlen(filename) + 1; 216c4ad8f98SLinus Torvalds 217c4ad8f98SLinus Torvalds result = __getname(); 218c4ad8f98SLinus Torvalds if (unlikely(!result)) 219c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 220c4ad8f98SLinus Torvalds 22108518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 222fd2f7cb5SAl Viro result->name = (char *)result->iname; 22308518549SPaul Moore } else if (len <= PATH_MAX) { 22408518549SPaul Moore struct filename *tmp; 22508518549SPaul Moore 22608518549SPaul Moore tmp = kmalloc(sizeof(*tmp), GFP_KERNEL); 22708518549SPaul Moore if (unlikely(!tmp)) { 22808518549SPaul Moore __putname(result); 22908518549SPaul Moore return ERR_PTR(-ENOMEM); 23008518549SPaul Moore } 23108518549SPaul Moore tmp->name = (char *)result; 23208518549SPaul Moore result = tmp; 23308518549SPaul Moore } else { 23408518549SPaul Moore __putname(result); 23508518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23608518549SPaul Moore } 23708518549SPaul Moore memcpy((char *)result->name, filename, len); 238c4ad8f98SLinus Torvalds result->uptr = NULL; 239c4ad8f98SLinus Torvalds result->aname = NULL; 24055422d0bSPaul Moore result->refcnt = 1; 241fd3522fdSPaul Moore audit_getname(result); 242c4ad8f98SLinus Torvalds 243c4ad8f98SLinus Torvalds return result; 244c4ad8f98SLinus Torvalds } 245c4ad8f98SLinus Torvalds 24691a27b2aSJeff Layton void putname(struct filename *name) 2471da177e4SLinus Torvalds { 24855422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 24955422d0bSPaul Moore 25055422d0bSPaul Moore if (--name->refcnt > 0) 25155422d0bSPaul Moore return; 25255422d0bSPaul Moore 253fd2f7cb5SAl Viro if (name->name != name->iname) { 25455422d0bSPaul Moore __putname(name->name); 25555422d0bSPaul Moore kfree(name); 25655422d0bSPaul Moore } else 25755422d0bSPaul Moore __putname(name); 2581da177e4SLinus Torvalds } 2591da177e4SLinus Torvalds 260e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 261e77819e5SLinus Torvalds { 26284635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 263e77819e5SLinus Torvalds struct posix_acl *acl; 264e77819e5SLinus Torvalds 265e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2663567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2673567866bSAl Viro if (!acl) 268e77819e5SLinus Torvalds return -EAGAIN; 2693567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 270b8a7a3a6SAndreas Gruenbacher if (is_uncached_acl(acl)) 271e77819e5SLinus Torvalds return -ECHILD; 272206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 273e77819e5SLinus Torvalds } 274e77819e5SLinus Torvalds 2752982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2764e34e719SChristoph Hellwig if (IS_ERR(acl)) 2774e34e719SChristoph Hellwig return PTR_ERR(acl); 278e77819e5SLinus Torvalds if (acl) { 279e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 280e77819e5SLinus Torvalds posix_acl_release(acl); 281e77819e5SLinus Torvalds return error; 282e77819e5SLinus Torvalds } 28384635d68SLinus Torvalds #endif 284e77819e5SLinus Torvalds 285e77819e5SLinus Torvalds return -EAGAIN; 286e77819e5SLinus Torvalds } 287e77819e5SLinus Torvalds 2885909ccaaSLinus Torvalds /* 289948409c7SAndreas Gruenbacher * This does the basic permission checking 2905909ccaaSLinus Torvalds */ 2917e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2925909ccaaSLinus Torvalds { 29326cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2945909ccaaSLinus Torvalds 2958e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2965909ccaaSLinus Torvalds mode >>= 6; 2975909ccaaSLinus Torvalds else { 298e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2997e40145eSAl Viro int error = check_acl(inode, mask); 3005909ccaaSLinus Torvalds if (error != -EAGAIN) 3015909ccaaSLinus Torvalds return error; 3025909ccaaSLinus Torvalds } 3035909ccaaSLinus Torvalds 3045909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3055909ccaaSLinus Torvalds mode >>= 3; 3065909ccaaSLinus Torvalds } 3075909ccaaSLinus Torvalds 3085909ccaaSLinus Torvalds /* 3095909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3105909ccaaSLinus Torvalds */ 3119c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3125909ccaaSLinus Torvalds return 0; 3135909ccaaSLinus Torvalds return -EACCES; 3145909ccaaSLinus Torvalds } 3151da177e4SLinus Torvalds 3161da177e4SLinus Torvalds /** 3171da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3181da177e4SLinus Torvalds * @inode: inode to check access rights for 3198fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3201da177e4SLinus Torvalds * 3211da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3221da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3231da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 324b74c79e9SNick Piggin * are used for other things. 325b74c79e9SNick Piggin * 326b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 327b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 328b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3291da177e4SLinus Torvalds */ 3302830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3311da177e4SLinus Torvalds { 3325909ccaaSLinus Torvalds int ret; 3331da177e4SLinus Torvalds 3341da177e4SLinus Torvalds /* 335948409c7SAndreas Gruenbacher * Do the basic permission checks. 3361da177e4SLinus Torvalds */ 3377e40145eSAl Viro ret = acl_permission_check(inode, mask); 3385909ccaaSLinus Torvalds if (ret != -EACCES) 3395909ccaaSLinus Torvalds return ret; 3401da177e4SLinus Torvalds 341d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 342d594e7ecSAl Viro /* DACs are overridable for directories */ 34323adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 344d594e7ecSAl Viro return 0; 345d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34623adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34723adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 348d594e7ecSAl Viro return 0; 349d594e7ecSAl Viro return -EACCES; 350d594e7ecSAl Viro } 3511da177e4SLinus Torvalds /* 3521da177e4SLinus Torvalds * Read/write DACs are always overridable. 353d594e7ecSAl Viro * Executable DACs are overridable when there is 354d594e7ecSAl Viro * at least one exec bit set. 3551da177e4SLinus Torvalds */ 356d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 35723adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3581da177e4SLinus Torvalds return 0; 3591da177e4SLinus Torvalds 3601da177e4SLinus Torvalds /* 3611da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3621da177e4SLinus Torvalds */ 3637ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 364d594e7ecSAl Viro if (mask == MAY_READ) 36523adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3661da177e4SLinus Torvalds return 0; 3671da177e4SLinus Torvalds 3681da177e4SLinus Torvalds return -EACCES; 3691da177e4SLinus Torvalds } 3704d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3711da177e4SLinus Torvalds 3723ddcd056SLinus Torvalds /* 3733ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3743ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3753ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3763ddcd056SLinus Torvalds * permission function, use the fast case". 3773ddcd056SLinus Torvalds */ 3783ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3793ddcd056SLinus Torvalds { 3803ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3813ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3823ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3833ddcd056SLinus Torvalds 3843ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3853ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3863ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3873ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3883ddcd056SLinus Torvalds } 3893ddcd056SLinus Torvalds return generic_permission(inode, mask); 3903ddcd056SLinus Torvalds } 3913ddcd056SLinus Torvalds 392cb23beb5SChristoph Hellwig /** 3930bdaea90SDavid Howells * __inode_permission - Check for access rights to a given inode 3940bdaea90SDavid Howells * @inode: Inode to check permission on 3950bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 396cb23beb5SChristoph Hellwig * 3970bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. 398948409c7SAndreas Gruenbacher * 399948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4000bdaea90SDavid Howells * 4010bdaea90SDavid Howells * This does not check for a read-only file system. You probably want 4020bdaea90SDavid Howells * inode_permission(). 403cb23beb5SChristoph Hellwig */ 4040bdaea90SDavid Howells int __inode_permission(struct inode *inode, int mask) 4051da177e4SLinus Torvalds { 406e6305c43SAl Viro int retval; 4071da177e4SLinus Torvalds 4083ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 4091da177e4SLinus Torvalds /* 4101da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 4111da177e4SLinus Torvalds */ 4121da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 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 7527973387aSAl Viro static int unlazy_link(struct nameidata *nd, struct path *link, unsigned seq) 7537973387aSAl Viro { 7547973387aSAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 7557973387aSAl Viro drop_links(nd); 7567973387aSAl Viro nd->depth = 0; 7577973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 7587973387aSAl Viro nd->path.mnt = NULL; 7597973387aSAl Viro nd->path.dentry = NULL; 7607973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7617973387aSAl Viro nd->root.mnt = NULL; 7627973387aSAl Viro rcu_read_unlock(); 7637973387aSAl Viro } else if (likely(unlazy_walk(nd, NULL, 0)) == 0) { 7647973387aSAl Viro return 0; 7657973387aSAl Viro } 7667973387aSAl Viro path_put(link); 7677973387aSAl Viro return -ECHILD; 7687973387aSAl Viro } 7697973387aSAl Viro 7704ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 77134286d66SNick Piggin { 7724ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 77334286d66SNick Piggin } 77434286d66SNick Piggin 7759f1fafeeSAl Viro /** 7769f1fafeeSAl Viro * complete_walk - successful completion of path walk 7779f1fafeeSAl Viro * @nd: pointer nameidata 77839159de2SJeff Layton * 7799f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7809f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7819f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7829f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7839f1fafeeSAl Viro * need to drop nd->path. 78439159de2SJeff Layton */ 7859f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 78639159de2SJeff Layton { 78716c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 78839159de2SJeff Layton int status; 78939159de2SJeff Layton 7909f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 7919f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7929f1fafeeSAl Viro nd->root.mnt = NULL; 7936e9918b7SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 79448a066e7SAl Viro return -ECHILD; 79548a066e7SAl Viro } 7969f1fafeeSAl Viro 79716c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 79839159de2SJeff Layton return 0; 79939159de2SJeff Layton 800ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 80116c2cd71SAl Viro return 0; 80216c2cd71SAl Viro 803ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 80439159de2SJeff Layton if (status > 0) 80539159de2SJeff Layton return 0; 80639159de2SJeff Layton 80716c2cd71SAl Viro if (!status) 80839159de2SJeff Layton status = -ESTALE; 80916c2cd71SAl Viro 81039159de2SJeff Layton return status; 81139159de2SJeff Layton } 81239159de2SJeff Layton 81318d8c860SAl Viro static void set_root(struct nameidata *nd) 8142a737871SAl Viro { 81531e6b01fSNick Piggin struct fs_struct *fs = current->fs; 8169e6697e2SAl Viro 8179e6697e2SAl Viro if (nd->flags & LOOKUP_RCU) { 8188f47a016SAl Viro unsigned seq; 819c28cc364SNick Piggin 820c28cc364SNick Piggin do { 821c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 82231e6b01fSNick Piggin nd->root = fs->root; 8238f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 824c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 8259e6697e2SAl Viro } else { 8269e6697e2SAl Viro get_fs_root(fs, &nd->root); 8279e6697e2SAl Viro } 82831e6b01fSNick Piggin } 82931e6b01fSNick Piggin 8301d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 831051d3812SIan Kent { 832051d3812SIan Kent dput(path->dentry); 8334ac91378SJan Blunck if (path->mnt != nd->path.mnt) 834051d3812SIan Kent mntput(path->mnt); 835051d3812SIan Kent } 836051d3812SIan Kent 8377b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8387b9337aaSNick Piggin struct nameidata *nd) 839051d3812SIan Kent { 84031e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8414ac91378SJan Blunck dput(nd->path.dentry); 84231e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8434ac91378SJan Blunck mntput(nd->path.mnt); 8449a229683SHuang Shijie } 84531e6b01fSNick Piggin nd->path.mnt = path->mnt; 8464ac91378SJan Blunck nd->path.dentry = path->dentry; 847051d3812SIan Kent } 848051d3812SIan Kent 849248fb5b9SAl Viro static int nd_jump_root(struct nameidata *nd) 850248fb5b9SAl Viro { 851248fb5b9SAl Viro if (nd->flags & LOOKUP_RCU) { 852248fb5b9SAl Viro struct dentry *d; 853248fb5b9SAl Viro nd->path = nd->root; 854248fb5b9SAl Viro d = nd->path.dentry; 855248fb5b9SAl Viro nd->inode = d->d_inode; 856248fb5b9SAl Viro nd->seq = nd->root_seq; 857248fb5b9SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 858248fb5b9SAl Viro return -ECHILD; 859248fb5b9SAl Viro } else { 860248fb5b9SAl Viro path_put(&nd->path); 861248fb5b9SAl Viro nd->path = nd->root; 862248fb5b9SAl Viro path_get(&nd->path); 863248fb5b9SAl Viro nd->inode = nd->path.dentry->d_inode; 864248fb5b9SAl Viro } 865248fb5b9SAl Viro nd->flags |= LOOKUP_JUMPED; 866248fb5b9SAl Viro return 0; 867248fb5b9SAl Viro } 868248fb5b9SAl Viro 869b5fb63c1SChristoph Hellwig /* 8706b255391SAl Viro * Helper to directly jump to a known parsed path from ->get_link, 871b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 872b5fb63c1SChristoph Hellwig */ 8736e77137bSAl Viro void nd_jump_link(struct path *path) 874b5fb63c1SChristoph Hellwig { 8756e77137bSAl Viro struct nameidata *nd = current->nameidata; 876b5fb63c1SChristoph Hellwig path_put(&nd->path); 877b5fb63c1SChristoph Hellwig 878b5fb63c1SChristoph Hellwig nd->path = *path; 879b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 880b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 881b5fb63c1SChristoph Hellwig } 882b5fb63c1SChristoph Hellwig 883b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 884574197e0SAl Viro { 88521c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 886fceef393SAl Viro do_delayed_call(&last->done); 8876548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 888b9ff4429SAl Viro path_put(&last->link); 889574197e0SAl Viro } 890574197e0SAl Viro 891561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 892561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 893800179c9SKees Cook 894800179c9SKees Cook /** 895800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 89655852635SRandy Dunlap * @nd: nameidata pathwalk data 897800179c9SKees Cook * 898800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 899800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 900800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 901800179c9SKees Cook * processes from failing races against path names that may change out 902800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 903800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 904800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 905800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 906800179c9SKees Cook * 907800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 908800179c9SKees Cook */ 909fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 910800179c9SKees Cook { 911800179c9SKees Cook const struct inode *inode; 912800179c9SKees Cook const struct inode *parent; 9132d7f9e2aSSeth Forshee kuid_t puid; 914800179c9SKees Cook 915800179c9SKees Cook if (!sysctl_protected_symlinks) 916800179c9SKees Cook return 0; 917800179c9SKees Cook 918800179c9SKees Cook /* Allowed if owner and follower match. */ 919fceef393SAl Viro inode = nd->link_inode; 92081abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 921800179c9SKees Cook return 0; 922800179c9SKees Cook 923800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 924aa65fa35SAl Viro parent = nd->inode; 925800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 926800179c9SKees Cook return 0; 927800179c9SKees Cook 928800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 9292d7f9e2aSSeth Forshee puid = parent->i_uid; 9302d7f9e2aSSeth Forshee if (uid_valid(puid) && uid_eq(puid, inode->i_uid)) 931800179c9SKees Cook return 0; 932800179c9SKees Cook 93331956502SAl Viro if (nd->flags & LOOKUP_RCU) 93431956502SAl Viro return -ECHILD; 93531956502SAl Viro 9361cf2665bSAl Viro audit_log_link_denied("follow_link", &nd->stack[0].link); 937800179c9SKees Cook return -EACCES; 938800179c9SKees Cook } 939800179c9SKees Cook 940800179c9SKees Cook /** 941800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 942800179c9SKees Cook * @inode: the source inode to hardlink from 943800179c9SKees Cook * 944800179c9SKees Cook * Return false if at least one of the following conditions: 945800179c9SKees Cook * - inode is not a regular file 946800179c9SKees Cook * - inode is setuid 947800179c9SKees Cook * - inode is setgid and group-exec 948800179c9SKees Cook * - access failure for read and write 949800179c9SKees Cook * 950800179c9SKees Cook * Otherwise returns true. 951800179c9SKees Cook */ 952800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 953800179c9SKees Cook { 954800179c9SKees Cook umode_t mode = inode->i_mode; 955800179c9SKees Cook 956800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 957800179c9SKees Cook if (!S_ISREG(mode)) 958800179c9SKees Cook return false; 959800179c9SKees Cook 960800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 961800179c9SKees Cook if (mode & S_ISUID) 962800179c9SKees Cook return false; 963800179c9SKees Cook 964800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 965800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 966800179c9SKees Cook return false; 967800179c9SKees Cook 968800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 969800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 970800179c9SKees Cook return false; 971800179c9SKees Cook 972800179c9SKees Cook return true; 973800179c9SKees Cook } 974800179c9SKees Cook 975800179c9SKees Cook /** 976800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 977800179c9SKees Cook * @link: the source to hardlink from 978800179c9SKees Cook * 979800179c9SKees Cook * Block hardlink when all of: 980800179c9SKees Cook * - sysctl_protected_hardlinks enabled 981800179c9SKees Cook * - fsuid does not match inode 982800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 983f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 984800179c9SKees Cook * 985800179c9SKees Cook * Returns 0 if successful, -ve on error. 986800179c9SKees Cook */ 987800179c9SKees Cook static int may_linkat(struct path *link) 988800179c9SKees Cook { 989800179c9SKees Cook struct inode *inode; 990800179c9SKees Cook 991800179c9SKees Cook if (!sysctl_protected_hardlinks) 992800179c9SKees Cook return 0; 993800179c9SKees Cook 994800179c9SKees Cook inode = link->dentry->d_inode; 995800179c9SKees Cook 996800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 997800179c9SKees Cook * otherwise, it must be a safe source. 998800179c9SKees Cook */ 999f2ca3796SDirk Steinmetz if (inode_owner_or_capable(inode) || safe_hardlink_source(inode)) 1000800179c9SKees Cook return 0; 1001800179c9SKees Cook 1002a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 1003800179c9SKees Cook return -EPERM; 1004800179c9SKees Cook } 1005800179c9SKees Cook 10063b2e7f75SAl Viro static __always_inline 10073b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 10081da177e4SLinus Torvalds { 1009ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 10101cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 1011fceef393SAl Viro struct inode *inode = nd->link_inode; 10126d7b5aaeSAl Viro int error; 10130a959df5SAl Viro const char *res; 10141da177e4SLinus Torvalds 10158fa9dd24SNeilBrown if (!(nd->flags & LOOKUP_RCU)) { 10168fa9dd24SNeilBrown touch_atime(&last->link); 10178fa9dd24SNeilBrown cond_resched(); 10188fa9dd24SNeilBrown } else if (atime_needs_update(&last->link, inode)) { 10198fa9dd24SNeilBrown if (unlikely(unlazy_walk(nd, NULL, 0))) 10208fa9dd24SNeilBrown return ERR_PTR(-ECHILD); 10218fa9dd24SNeilBrown touch_atime(&last->link); 10228fa9dd24SNeilBrown } 10238fa9dd24SNeilBrown 1024bda0be7aSNeilBrown error = security_inode_follow_link(dentry, inode, 1025bda0be7aSNeilBrown nd->flags & LOOKUP_RCU); 1026bda0be7aSNeilBrown if (unlikely(error)) 10276920a440SAl Viro return ERR_PTR(error); 102836f3b4f6SAl Viro 102986acdca1SAl Viro nd->last_type = LAST_BIND; 1030d4dee48bSAl Viro res = inode->i_link; 1031d4dee48bSAl Viro if (!res) { 1032fceef393SAl Viro const char * (*get)(struct dentry *, struct inode *, 1033fceef393SAl Viro struct delayed_call *); 1034fceef393SAl Viro get = inode->i_op->get_link; 10358c1b4566SAl Viro if (nd->flags & LOOKUP_RCU) { 1036fceef393SAl Viro res = get(NULL, inode, &last->done); 10376b255391SAl Viro if (res == ERR_PTR(-ECHILD)) { 10388c1b4566SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 10398c1b4566SAl Viro return ERR_PTR(-ECHILD); 1040fceef393SAl Viro res = get(dentry, inode, &last->done); 10418c1b4566SAl Viro } 10426b255391SAl Viro } else { 1043fceef393SAl Viro res = get(dentry, inode, &last->done); 10446b255391SAl Viro } 1045fceef393SAl Viro if (IS_ERR_OR_NULL(res)) 1046fab51e8aSAl Viro return res; 10470a959df5SAl Viro } 1048fab51e8aSAl Viro if (*res == '/') { 1049fab51e8aSAl Viro if (!nd->root.mnt) 1050fab51e8aSAl Viro set_root(nd); 1051248fb5b9SAl Viro if (unlikely(nd_jump_root(nd))) 1052fab51e8aSAl Viro return ERR_PTR(-ECHILD); 1053fab51e8aSAl Viro while (unlikely(*++res == '/')) 1054fab51e8aSAl Viro ; 1055fab51e8aSAl Viro } 1056fab51e8aSAl Viro if (!*res) 1057fab51e8aSAl Viro res = NULL; 10580a959df5SAl Viro return res; 10590a959df5SAl Viro } 10606d7b5aaeSAl Viro 1061f015f126SDavid Howells /* 1062f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1063f015f126SDavid Howells * 1064f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1065f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1066f015f126SDavid Howells * Up is towards /. 1067f015f126SDavid Howells * 1068f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1069f015f126SDavid Howells * root. 1070f015f126SDavid Howells */ 1071bab77ebfSAl Viro int follow_up(struct path *path) 10721da177e4SLinus Torvalds { 10730714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 10740714a533SAl Viro struct mount *parent; 10751da177e4SLinus Torvalds struct dentry *mountpoint; 107699b7db7bSNick Piggin 107748a066e7SAl Viro read_seqlock_excl(&mount_lock); 10780714a533SAl Viro parent = mnt->mnt_parent; 10793c0a6163SAl Viro if (parent == mnt) { 108048a066e7SAl Viro read_sequnlock_excl(&mount_lock); 10811da177e4SLinus Torvalds return 0; 10821da177e4SLinus Torvalds } 10830714a533SAl Viro mntget(&parent->mnt); 1084a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 108548a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1086bab77ebfSAl Viro dput(path->dentry); 1087bab77ebfSAl Viro path->dentry = mountpoint; 1088bab77ebfSAl Viro mntput(path->mnt); 10890714a533SAl Viro path->mnt = &parent->mnt; 10901da177e4SLinus Torvalds return 1; 10911da177e4SLinus Torvalds } 10924d359507SAl Viro EXPORT_SYMBOL(follow_up); 10931da177e4SLinus Torvalds 1094b5c84bf6SNick Piggin /* 10959875cf80SDavid Howells * Perform an automount 10969875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 10979875cf80SDavid Howells * were called with. 10981da177e4SLinus Torvalds */ 1099756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 11009875cf80SDavid Howells bool *need_mntput) 110131e6b01fSNick Piggin { 11029875cf80SDavid Howells struct vfsmount *mnt; 1103aeaa4a79SEric W. Biederman const struct cred *old_cred; 1104ea5b778aSDavid Howells int err; 11059875cf80SDavid Howells 11069875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 11079875cf80SDavid Howells return -EREMOTE; 11089875cf80SDavid Howells 11090ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 11100ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 11110ec26fd0SMiklos Szeredi * the name. 11120ec26fd0SMiklos Szeredi * 11130ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 11145a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 11150ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 11160ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 11170ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 11180ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 11195a30d8a2SDavid Howells */ 1120756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 1121d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 11225a30d8a2SDavid Howells path->dentry->d_inode) 11239875cf80SDavid Howells return -EISDIR; 11240ec26fd0SMiklos Szeredi 1125aeaa4a79SEric W. Biederman if (path->dentry->d_sb->s_user_ns != &init_user_ns) 1126aeaa4a79SEric W. Biederman return -EACCES; 1127aeaa4a79SEric W. Biederman 1128756daf26SNeilBrown nd->total_link_count++; 1129756daf26SNeilBrown if (nd->total_link_count >= 40) 11309875cf80SDavid Howells return -ELOOP; 11319875cf80SDavid Howells 1132aeaa4a79SEric W. Biederman old_cred = override_creds(&init_cred); 11339875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 1134aeaa4a79SEric W. Biederman revert_creds(old_cred); 11359875cf80SDavid Howells if (IS_ERR(mnt)) { 11369875cf80SDavid Howells /* 11379875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 11389875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 11399875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 11409875cf80SDavid Howells * 11419875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 11429875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 11439875cf80SDavid Howells * the path is inaccessible and we should say so. 11449875cf80SDavid Howells */ 1145756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 11469875cf80SDavid Howells return -EREMOTE; 11479875cf80SDavid Howells return PTR_ERR(mnt); 114831e6b01fSNick Piggin } 1149ea5b778aSDavid Howells 11509875cf80SDavid Howells if (!mnt) /* mount collision */ 11519875cf80SDavid Howells return 0; 11529875cf80SDavid Howells 11538aef1884SAl Viro if (!*need_mntput) { 11548aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 11558aef1884SAl Viro mntget(path->mnt); 11568aef1884SAl Viro *need_mntput = true; 11578aef1884SAl Viro } 115819a167afSAl Viro err = finish_automount(mnt, path); 1159ea5b778aSDavid Howells 1160ea5b778aSDavid Howells switch (err) { 1161ea5b778aSDavid Howells case -EBUSY: 1162ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 116319a167afSAl Viro return 0; 1164ea5b778aSDavid Howells case 0: 11658aef1884SAl Viro path_put(path); 11669875cf80SDavid Howells path->mnt = mnt; 11679875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 11689875cf80SDavid Howells return 0; 116919a167afSAl Viro default: 117019a167afSAl Viro return err; 11719875cf80SDavid Howells } 117219a167afSAl Viro 1173ea5b778aSDavid Howells } 11749875cf80SDavid Howells 11759875cf80SDavid Howells /* 11769875cf80SDavid Howells * Handle a dentry that is managed in some way. 1177cc53ce53SDavid Howells * - Flagged for transit management (autofs) 11789875cf80SDavid Howells * - Flagged as mountpoint 11799875cf80SDavid Howells * - Flagged as automount point 11809875cf80SDavid Howells * 11819875cf80SDavid Howells * This may only be called in refwalk mode. 11829875cf80SDavid Howells * 11839875cf80SDavid Howells * Serialization is taken care of in namespace.c 11849875cf80SDavid Howells */ 1185756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 11869875cf80SDavid Howells { 11878aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 11889875cf80SDavid Howells unsigned managed; 11899875cf80SDavid Howells bool need_mntput = false; 11908aef1884SAl Viro int ret = 0; 11919875cf80SDavid Howells 11929875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 11939875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 11949875cf80SDavid Howells * the components of that value change under us */ 11959875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 11969875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 11979875cf80SDavid Howells unlikely(managed != 0)) { 1198cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1199cc53ce53SDavid Howells * being held. */ 1200cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1201cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1202cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 12031aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1204cc53ce53SDavid Howells if (ret < 0) 12058aef1884SAl Viro break; 1206cc53ce53SDavid Howells } 1207cc53ce53SDavid Howells 12089875cf80SDavid Howells /* Transit to a mounted filesystem. */ 12099875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 12109875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12119875cf80SDavid Howells if (mounted) { 12129875cf80SDavid Howells dput(path->dentry); 12139875cf80SDavid Howells if (need_mntput) 1214463ffb2eSAl Viro mntput(path->mnt); 1215463ffb2eSAl Viro path->mnt = mounted; 1216463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 12179875cf80SDavid Howells need_mntput = true; 12189875cf80SDavid Howells continue; 1219463ffb2eSAl Viro } 1220463ffb2eSAl Viro 12219875cf80SDavid Howells /* Something is mounted on this dentry in another 12229875cf80SDavid Howells * namespace and/or whatever was mounted there in this 122348a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 122448a066e7SAl Viro * get it */ 12251da177e4SLinus Torvalds } 12269875cf80SDavid Howells 12279875cf80SDavid Howells /* Handle an automount point */ 12289875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1229756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 12309875cf80SDavid Howells if (ret < 0) 12318aef1884SAl Viro break; 12329875cf80SDavid Howells continue; 12339875cf80SDavid Howells } 12349875cf80SDavid Howells 12359875cf80SDavid Howells /* We didn't change the current path point */ 12369875cf80SDavid Howells break; 12379875cf80SDavid Howells } 12388aef1884SAl Viro 12398aef1884SAl Viro if (need_mntput && path->mnt == mnt) 12408aef1884SAl Viro mntput(path->mnt); 1241e9742b53SAl Viro if (ret == -EISDIR || !ret) 1242e9742b53SAl Viro ret = 1; 12438402752eSAl Viro if (need_mntput) 12448402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 12458402752eSAl Viro if (unlikely(ret < 0)) 12468402752eSAl Viro path_put_conditional(path, nd); 12478402752eSAl Viro return ret; 12481da177e4SLinus Torvalds } 12491da177e4SLinus Torvalds 1250cc53ce53SDavid Howells int follow_down_one(struct path *path) 12511da177e4SLinus Torvalds { 12521da177e4SLinus Torvalds struct vfsmount *mounted; 12531da177e4SLinus Torvalds 12541c755af4SAl Viro mounted = lookup_mnt(path); 12551da177e4SLinus Torvalds if (mounted) { 12569393bd07SAl Viro dput(path->dentry); 12579393bd07SAl Viro mntput(path->mnt); 12589393bd07SAl Viro path->mnt = mounted; 12599393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12601da177e4SLinus Torvalds return 1; 12611da177e4SLinus Torvalds } 12621da177e4SLinus Torvalds return 0; 12631da177e4SLinus Torvalds } 12644d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12651da177e4SLinus Torvalds 1266b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 126762a7375eSIan Kent { 1268b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1269b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 127062a7375eSIan Kent } 127162a7375eSIan Kent 12729875cf80SDavid Howells /* 1273287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1274287548e4SAl Viro * we meet a managed dentry that would need blocking. 12759875cf80SDavid Howells */ 12769875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1277254cf582SAl Viro struct inode **inode, unsigned *seqp) 12789875cf80SDavid Howells { 127962a7375eSIan Kent for (;;) { 1280c7105365SAl Viro struct mount *mounted; 128162a7375eSIan Kent /* 128262a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 128362a7375eSIan Kent * that wants to block transit. 128462a7375eSIan Kent */ 1285b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1286b8faf035SNeilBrown case -ECHILD: 1287b8faf035SNeilBrown default: 1288ab90911fSDavid Howells return false; 1289b8faf035SNeilBrown case -EISDIR: 1290b8faf035SNeilBrown return true; 1291b8faf035SNeilBrown case 0: 1292b8faf035SNeilBrown break; 1293b8faf035SNeilBrown } 129462a7375eSIan Kent 129562a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1296b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 129762a7375eSIan Kent 1298474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 12999875cf80SDavid Howells if (!mounted) 13009875cf80SDavid Howells break; 1301c7105365SAl Viro path->mnt = &mounted->mnt; 1302c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1303a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1304254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 130559430262SLinus Torvalds /* 130659430262SLinus Torvalds * Update the inode too. We don't need to re-check the 130759430262SLinus Torvalds * dentry sequence number here after this d_inode read, 130859430262SLinus Torvalds * because a mount-point is always pinned. 130959430262SLinus Torvalds */ 131059430262SLinus Torvalds *inode = path->dentry->d_inode; 13119875cf80SDavid Howells } 1312f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1313b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1314287548e4SAl Viro } 1315287548e4SAl Viro 131631e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 131731e6b01fSNick Piggin { 13184023bfc9SAl Viro struct inode *inode = nd->inode; 131931e6b01fSNick Piggin 132031e6b01fSNick Piggin while (1) { 1321aed434adSAl Viro if (path_equal(&nd->path, &nd->root)) 132231e6b01fSNick Piggin break; 132331e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 132431e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 132531e6b01fSNick Piggin struct dentry *parent = old->d_parent; 132631e6b01fSNick Piggin unsigned seq; 132731e6b01fSNick Piggin 13284023bfc9SAl Viro inode = parent->d_inode; 132931e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 1330aed434adSAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 1331aed434adSAl Viro return -ECHILD; 133231e6b01fSNick Piggin nd->path.dentry = parent; 133331e6b01fSNick Piggin nd->seq = seq; 1334397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 1335397d425dSEric W. Biederman return -ENOENT; 133631e6b01fSNick Piggin break; 1337aed434adSAl Viro } else { 1338aed434adSAl Viro struct mount *mnt = real_mount(nd->path.mnt); 1339aed434adSAl Viro struct mount *mparent = mnt->mnt_parent; 1340aed434adSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1341aed434adSAl Viro struct inode *inode2 = mountpoint->d_inode; 1342aed434adSAl Viro unsigned seq = read_seqcount_begin(&mountpoint->d_seq); 1343aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1344aed434adSAl Viro return -ECHILD; 1345aed434adSAl Viro if (&mparent->mnt == nd->path.mnt) 134631e6b01fSNick Piggin break; 1347aed434adSAl Viro /* we know that mountpoint was pinned */ 1348aed434adSAl Viro nd->path.dentry = mountpoint; 1349aed434adSAl Viro nd->path.mnt = &mparent->mnt; 1350aed434adSAl Viro inode = inode2; 1351aed434adSAl Viro nd->seq = seq; 135231e6b01fSNick Piggin } 1353aed434adSAl Viro } 1354aed434adSAl Viro while (unlikely(d_mountpoint(nd->path.dentry))) { 1355b37199e6SAl Viro struct mount *mounted; 1356b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1357aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1358aed434adSAl Viro return -ECHILD; 1359b37199e6SAl Viro if (!mounted) 1360b37199e6SAl Viro break; 1361b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1362b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 13634023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1364b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1365b37199e6SAl Viro } 13664023bfc9SAl Viro nd->inode = inode; 136731e6b01fSNick Piggin return 0; 136831e6b01fSNick Piggin } 136931e6b01fSNick Piggin 13709875cf80SDavid Howells /* 1371cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1372cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1373cc53ce53SDavid Howells * caller is permitted to proceed or not. 1374cc53ce53SDavid Howells */ 13757cc90cc3SAl Viro int follow_down(struct path *path) 1376cc53ce53SDavid Howells { 1377cc53ce53SDavid Howells unsigned managed; 1378cc53ce53SDavid Howells int ret; 1379cc53ce53SDavid Howells 1380cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1381cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1382cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1383cc53ce53SDavid Howells * being held. 1384cc53ce53SDavid Howells * 1385cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1386cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1387cc53ce53SDavid Howells * other than its daemon the right to mount on its 1388cc53ce53SDavid Howells * superstructure. 1389cc53ce53SDavid Howells * 1390cc53ce53SDavid Howells * The filesystem may sleep at this point. 1391cc53ce53SDavid Howells */ 1392cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1393cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1394cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1395ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 13961aed3e42SAl Viro path->dentry, false); 1397cc53ce53SDavid Howells if (ret < 0) 1398cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1399cc53ce53SDavid Howells } 1400cc53ce53SDavid Howells 1401cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1402cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1403cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1404cc53ce53SDavid Howells if (!mounted) 1405cc53ce53SDavid Howells break; 1406cc53ce53SDavid Howells dput(path->dentry); 1407cc53ce53SDavid Howells mntput(path->mnt); 1408cc53ce53SDavid Howells path->mnt = mounted; 1409cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1410cc53ce53SDavid Howells continue; 1411cc53ce53SDavid Howells } 1412cc53ce53SDavid Howells 1413cc53ce53SDavid Howells /* Don't handle automount points here */ 1414cc53ce53SDavid Howells break; 1415cc53ce53SDavid Howells } 1416cc53ce53SDavid Howells return 0; 1417cc53ce53SDavid Howells } 14184d359507SAl Viro EXPORT_SYMBOL(follow_down); 1419cc53ce53SDavid Howells 1420cc53ce53SDavid Howells /* 14219875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 14229875cf80SDavid Howells */ 14239875cf80SDavid Howells static void follow_mount(struct path *path) 14249875cf80SDavid Howells { 14259875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 14269875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 14279875cf80SDavid Howells if (!mounted) 14289875cf80SDavid Howells break; 14299875cf80SDavid Howells dput(path->dentry); 14309875cf80SDavid Howells mntput(path->mnt); 14319875cf80SDavid Howells path->mnt = mounted; 14329875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 14339875cf80SDavid Howells } 14349875cf80SDavid Howells } 14359875cf80SDavid Howells 1436eedf265aSEric W. Biederman static int path_parent_directory(struct path *path) 1437eedf265aSEric W. Biederman { 1438eedf265aSEric W. Biederman struct dentry *old = path->dentry; 1439eedf265aSEric W. Biederman /* rare case of legitimate dget_parent()... */ 1440eedf265aSEric W. Biederman path->dentry = dget_parent(path->dentry); 1441eedf265aSEric W. Biederman dput(old); 1442eedf265aSEric W. Biederman if (unlikely(!path_connected(path))) 1443eedf265aSEric W. Biederman return -ENOENT; 1444eedf265aSEric W. Biederman return 0; 1445eedf265aSEric W. Biederman } 1446eedf265aSEric W. Biederman 1447397d425dSEric W. Biederman static int follow_dotdot(struct nameidata *nd) 14481da177e4SLinus Torvalds { 14491da177e4SLinus Torvalds while(1) { 14502a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 14512a737871SAl Viro nd->path.mnt == nd->root.mnt) { 14521da177e4SLinus Torvalds break; 14531da177e4SLinus Torvalds } 14544ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 1455eedf265aSEric W. Biederman int ret = path_parent_directory(&nd->path); 1456eedf265aSEric W. Biederman if (ret) 1457eedf265aSEric W. Biederman return ret; 14581da177e4SLinus Torvalds break; 14591da177e4SLinus Torvalds } 14603088dd70SAl Viro if (!follow_up(&nd->path)) 14611da177e4SLinus Torvalds break; 14621da177e4SLinus Torvalds } 146379ed0226SAl Viro follow_mount(&nd->path); 146431e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 1465397d425dSEric W. Biederman return 0; 14661da177e4SLinus Torvalds } 14671da177e4SLinus Torvalds 14681da177e4SLinus Torvalds /* 1469f4fdace9SOleg Drokin * This looks up the name in dcache and possibly revalidates the found dentry. 1470f4fdace9SOleg Drokin * NULL is returned if the dentry does not exist in the cache. 1471baa03890SNick Piggin */ 1472e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1473e3c13928SAl Viro struct dentry *dir, 14746c51e513SAl Viro unsigned int flags) 1475baa03890SNick Piggin { 1476baa03890SNick Piggin struct dentry *dentry; 1477bad61189SMiklos Szeredi int error; 1478baa03890SNick Piggin 1479bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1480bad61189SMiklos Szeredi if (dentry) { 148139e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1482201f956eSAl Viro error = d_revalidate(dentry, flags); 1483bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 148474ff0ffcSAl Viro if (!error) 14855542aa2fSEric W. Biederman d_invalidate(dentry); 1486bad61189SMiklos Szeredi dput(dentry); 148774ff0ffcSAl Viro return ERR_PTR(error); 1488bad61189SMiklos Szeredi } 1489bad61189SMiklos Szeredi } 1490bad61189SMiklos Szeredi } 1491baa03890SNick Piggin return dentry; 1492baa03890SNick Piggin } 1493baa03890SNick Piggin 1494baa03890SNick Piggin /* 149513a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 149613a2c3beSJ. Bruce Fields * unhashed. 1497bad61189SMiklos Szeredi * 1498bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 149944396f4bSJosef Bacik */ 1500bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 150172bd866aSAl Viro unsigned int flags) 150244396f4bSJosef Bacik { 150344396f4bSJosef Bacik struct dentry *old; 150444396f4bSJosef Bacik 150544396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1506bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1507e188dc02SMiklos Szeredi dput(dentry); 150844396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1509e188dc02SMiklos Szeredi } 151044396f4bSJosef Bacik 151172bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 151244396f4bSJosef Bacik if (unlikely(old)) { 151344396f4bSJosef Bacik dput(dentry); 151444396f4bSJosef Bacik dentry = old; 151544396f4bSJosef Bacik } 151644396f4bSJosef Bacik return dentry; 151744396f4bSJosef Bacik } 151844396f4bSJosef Bacik 1519e3c13928SAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 152072bd866aSAl Viro struct dentry *base, unsigned int flags) 1521a3255546SAl Viro { 15226c51e513SAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 1523a3255546SAl Viro 15246c51e513SAl Viro if (dentry) 1525a3255546SAl Viro return dentry; 1526bad61189SMiklos Szeredi 15276c51e513SAl Viro dentry = d_alloc(base, name); 15286c51e513SAl Viro if (unlikely(!dentry)) 15296c51e513SAl Viro return ERR_PTR(-ENOMEM); 15306c51e513SAl Viro 153172bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1532a3255546SAl Viro } 1533a3255546SAl Viro 1534e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 1535254cf582SAl Viro struct path *path, struct inode **inode, 1536254cf582SAl Viro unsigned *seqp) 15371da177e4SLinus Torvalds { 15384ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 153931e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 15405a18fff2SAl Viro int status = 1; 15419875cf80SDavid Howells int err; 15429875cf80SDavid Howells 15433cac260aSAl Viro /* 1544b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 15455d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 15465d0f49c1SAl Viro * going to fall back to non-racy lookup. 1547b04f784eSNick Piggin */ 154831e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 154931e6b01fSNick Piggin unsigned seq; 1550766c4cbfSAl Viro bool negative; 1551da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15525d0f49c1SAl Viro if (unlikely(!dentry)) { 15535d0f49c1SAl Viro if (unlazy_walk(nd, NULL, 0)) 15545d0f49c1SAl Viro return -ECHILD; 1555e9742b53SAl Viro return 0; 15565d0f49c1SAl Viro } 15575a18fff2SAl Viro 155812f8ad4bSLinus Torvalds /* 155912f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 156012f8ad4bSLinus Torvalds * the dentry name information from lookup. 156112f8ad4bSLinus Torvalds */ 156263afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1563766c4cbfSAl Viro negative = d_is_negative(dentry); 15645d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 156512f8ad4bSLinus Torvalds return -ECHILD; 156612f8ad4bSLinus Torvalds 156712f8ad4bSLinus Torvalds /* 156812f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 156912f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 157012f8ad4bSLinus Torvalds * 157112f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 157212f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 157312f8ad4bSLinus Torvalds */ 15745d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 157531e6b01fSNick Piggin return -ECHILD; 15765a18fff2SAl Viro 1577254cf582SAl Viro *seqp = seq; 15785d0f49c1SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 15794ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15805a18fff2SAl Viro if (unlikely(status <= 0)) { 15815d0f49c1SAl Viro if (unlazy_walk(nd, dentry, seq)) 15825d0f49c1SAl Viro return -ECHILD; 15835d0f49c1SAl Viro if (status == -ECHILD) 15845d0f49c1SAl Viro status = d_revalidate(dentry, nd->flags); 15855d0f49c1SAl Viro } else { 1586daf3761cSTrond Myklebust /* 1587daf3761cSTrond Myklebust * Note: do negative dentry check after revalidation in 1588daf3761cSTrond Myklebust * case that drops it. 1589daf3761cSTrond Myklebust */ 15905d0f49c1SAl Viro if (unlikely(negative)) 1591daf3761cSTrond Myklebust return -ENOENT; 159231e6b01fSNick Piggin path->mnt = mnt; 159331e6b01fSNick Piggin path->dentry = dentry; 1594254cf582SAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 1595e9742b53SAl Viro return 1; 1596254cf582SAl Viro if (unlazy_walk(nd, dentry, seq)) 15975a18fff2SAl Viro return -ECHILD; 15985d0f49c1SAl Viro } 15995a18fff2SAl Viro } else { 1600e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 160181e6f520SAl Viro if (unlikely(!dentry)) 1602e9742b53SAl Viro return 0; 16035d0f49c1SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 16044ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 16055d0f49c1SAl Viro } 16065a18fff2SAl Viro if (unlikely(status <= 0)) { 1607e9742b53SAl Viro if (!status) 16085d0f49c1SAl Viro d_invalidate(dentry); 16095a18fff2SAl Viro dput(dentry); 16105a18fff2SAl Viro return status; 16115a18fff2SAl Viro } 1612766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1613766c4cbfSAl Viro dput(dentry); 1614766c4cbfSAl Viro return -ENOENT; 1615766c4cbfSAl Viro } 16165d0f49c1SAl Viro 16171da177e4SLinus Torvalds path->mnt = mnt; 16181da177e4SLinus Torvalds path->dentry = dentry; 1619756daf26SNeilBrown err = follow_managed(path, nd); 1620e9742b53SAl Viro if (likely(err > 0)) 162163afdfc7SDavid Howells *inode = d_backing_inode(path->dentry); 16228402752eSAl Viro return err; 1623697f514dSMiklos Szeredi } 1624697f514dSMiklos Szeredi 1625697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1626e3c13928SAl Viro static struct dentry *lookup_slow(const struct qstr *name, 1627e3c13928SAl Viro struct dentry *dir, 1628e3c13928SAl Viro unsigned int flags) 1629697f514dSMiklos Szeredi { 163094bdd655SAl Viro struct dentry *dentry = ERR_PTR(-ENOENT), *old; 16311936386eSAl Viro struct inode *inode = dir->d_inode; 1632d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 16331936386eSAl Viro 16349902af79SAl Viro inode_lock_shared(inode); 16351936386eSAl Viro /* Don't go there if it's already dead */ 163694bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 163794bdd655SAl Viro goto out; 163894bdd655SAl Viro again: 1639d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 164094bdd655SAl Viro if (IS_ERR(dentry)) 164194bdd655SAl Viro goto out; 164294bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1643949a852eSAl Viro if ((dentry->d_flags & DCACHE_OP_REVALIDATE) && 1644949a852eSAl Viro !(flags & LOOKUP_NO_REVAL)) { 1645949a852eSAl Viro int error = d_revalidate(dentry, flags); 1646949a852eSAl Viro if (unlikely(error <= 0)) { 164794bdd655SAl Viro if (!error) { 1648949a852eSAl Viro d_invalidate(dentry); 1649949a852eSAl Viro dput(dentry); 165094bdd655SAl Viro goto again; 165194bdd655SAl Viro } 165294bdd655SAl Viro dput(dentry); 1653949a852eSAl Viro dentry = ERR_PTR(error); 1654949a852eSAl Viro } 1655949a852eSAl Viro } 165694bdd655SAl Viro } else { 16571936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 165885c7f810SAl Viro d_lookup_done(dentry); 16591936386eSAl Viro if (unlikely(old)) { 16601936386eSAl Viro dput(dentry); 16611936386eSAl Viro dentry = old; 1662949a852eSAl Viro } 1663949a852eSAl Viro } 166494bdd655SAl Viro out: 16659902af79SAl Viro inode_unlock_shared(inode); 1666e3c13928SAl Viro return dentry; 16671da177e4SLinus Torvalds } 16681da177e4SLinus Torvalds 166952094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 167052094c8aSAl Viro { 167152094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16724ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 167352094c8aSAl Viro if (err != -ECHILD) 167452094c8aSAl Viro return err; 16756e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 167652094c8aSAl Viro return -ECHILD; 167752094c8aSAl Viro } 16784ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 167952094c8aSAl Viro } 168052094c8aSAl Viro 16819856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 16829856fa1bSAl Viro { 16839856fa1bSAl Viro if (type == LAST_DOTDOT) { 16849e6697e2SAl Viro if (!nd->root.mnt) 16859e6697e2SAl Viro set_root(nd); 16869856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 168770291aecSAl Viro return follow_dotdot_rcu(nd); 16889856fa1bSAl Viro } else 1689397d425dSEric W. Biederman return follow_dotdot(nd); 16909856fa1bSAl Viro } 16919856fa1bSAl Viro return 0; 16929856fa1bSAl Viro } 16939856fa1bSAl Viro 1694181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1695181548c0SAl Viro struct inode *inode, unsigned seq) 1696d63ff28fSAl Viro { 1697626de996SAl Viro int error; 16981cf2665bSAl Viro struct saved *last; 1699756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1700626de996SAl Viro path_to_nameidata(link, nd); 1701626de996SAl Viro return -ELOOP; 1702626de996SAl Viro } 1703bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1704cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1705cd179f44SAl Viro mntget(link->mnt); 17067973387aSAl Viro } 1707626de996SAl Viro error = nd_alloc_stack(nd); 1708626de996SAl Viro if (unlikely(error)) { 1709bc40aee0SAl Viro if (error == -ECHILD) { 1710bc40aee0SAl Viro if (unlikely(unlazy_link(nd, link, seq))) 1711bc40aee0SAl Viro return -ECHILD; 1712bc40aee0SAl Viro error = nd_alloc_stack(nd); 1713bc40aee0SAl Viro } 1714bc40aee0SAl Viro if (error) { 1715cd179f44SAl Viro path_put(link); 1716626de996SAl Viro return error; 1717626de996SAl Viro } 1718bc40aee0SAl Viro } 1719626de996SAl Viro 1720ab104923SAl Viro last = nd->stack + nd->depth++; 17211cf2665bSAl Viro last->link = *link; 1722fceef393SAl Viro clear_delayed_call(&last->done); 1723fceef393SAl Viro nd->link_inode = inode; 17240450b2d1SAl Viro last->seq = seq; 1725d63ff28fSAl Viro return 1; 1726d63ff28fSAl Viro } 1727d63ff28fSAl Viro 17283ddcd056SLinus Torvalds /* 17293ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 17303ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 17313ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 17323ddcd056SLinus Torvalds * for the common case. 17333ddcd056SLinus Torvalds */ 1734254cf582SAl Viro static inline int should_follow_link(struct nameidata *nd, struct path *link, 1735181548c0SAl Viro int follow, 1736181548c0SAl Viro struct inode *inode, unsigned seq) 17373ddcd056SLinus Torvalds { 1738d63ff28fSAl Viro if (likely(!d_is_symlink(link->dentry))) 1739d63ff28fSAl Viro return 0; 1740d63ff28fSAl Viro if (!follow) 1741d63ff28fSAl Viro return 0; 1742a7f77542SAl Viro /* make sure that d_is_symlink above matches inode */ 1743a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 1744a7f77542SAl Viro if (read_seqcount_retry(&link->dentry->d_seq, seq)) 1745a7f77542SAl Viro return -ECHILD; 1746a7f77542SAl Viro } 1747181548c0SAl Viro return pick_link(nd, link, inode, seq); 17483ddcd056SLinus Torvalds } 17493ddcd056SLinus Torvalds 17504693a547SAl Viro enum {WALK_GET = 1, WALK_PUT = 2}; 17514693a547SAl Viro 17524693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1753ce57dfc1SAl Viro { 1754caa85634SAl Viro struct path path; 1755ce57dfc1SAl Viro struct inode *inode; 1756254cf582SAl Viro unsigned seq; 1757ce57dfc1SAl Viro int err; 1758ce57dfc1SAl Viro /* 1759ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1760ce57dfc1SAl Viro * to be able to know about the current root directory and 1761ce57dfc1SAl Viro * parent relationships. 1762ce57dfc1SAl Viro */ 17634693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 17644693a547SAl Viro err = handle_dots(nd, nd->last_type); 17654693a547SAl Viro if (flags & WALK_PUT) 17664693a547SAl Viro put_link(nd); 17674693a547SAl Viro return err; 17684693a547SAl Viro } 1769254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1770e9742b53SAl Viro if (unlikely(err <= 0)) { 1771697f514dSMiklos Szeredi if (err < 0) 1772f0a9ba70SAl Viro return err; 1773e3c13928SAl Viro path.dentry = lookup_slow(&nd->last, nd->path.dentry, 1774e3c13928SAl Viro nd->flags); 1775e3c13928SAl Viro if (IS_ERR(path.dentry)) 1776e3c13928SAl Viro return PTR_ERR(path.dentry); 17777500c38aSAl Viro 1778e3c13928SAl Viro path.mnt = nd->path.mnt; 1779e3c13928SAl Viro err = follow_managed(&path, nd); 1780e3c13928SAl Viro if (unlikely(err < 0)) 1781f0a9ba70SAl Viro return err; 1782697f514dSMiklos Szeredi 17837500c38aSAl Viro if (unlikely(d_is_negative(path.dentry))) { 17847500c38aSAl Viro path_to_nameidata(&path, nd); 17857500c38aSAl Viro return -ENOENT; 17867500c38aSAl Viro } 17877500c38aSAl Viro 1788254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1789d4565649SAl Viro inode = d_backing_inode(path.dentry); 1790766c4cbfSAl Viro } 1791697f514dSMiklos Szeredi 17924693a547SAl Viro if (flags & WALK_PUT) 17934693a547SAl Viro put_link(nd); 1794181548c0SAl Viro err = should_follow_link(nd, &path, flags & WALK_GET, inode, seq); 1795d63ff28fSAl Viro if (unlikely(err)) 1796d63ff28fSAl Viro return err; 1797caa85634SAl Viro path_to_nameidata(&path, nd); 1798ce57dfc1SAl Viro nd->inode = inode; 1799254cf582SAl Viro nd->seq = seq; 1800ce57dfc1SAl Viro return 0; 1801ce57dfc1SAl Viro } 1802ce57dfc1SAl Viro 18031da177e4SLinus Torvalds /* 1804bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1805bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1806bfcfaa77SLinus Torvalds * 1807bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1808bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1809bfcfaa77SLinus Torvalds * fast. 1810bfcfaa77SLinus Torvalds * 1811bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1812bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1813bfcfaa77SLinus Torvalds * crossing operation. 1814bfcfaa77SLinus Torvalds * 1815bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1816bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1817bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1818bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1819bfcfaa77SLinus Torvalds */ 1820bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1821bfcfaa77SLinus Torvalds 1822f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1823bfcfaa77SLinus Torvalds 1824468a9428SGeorge Spelvin #ifdef HASH_MIX 1825bfcfaa77SLinus Torvalds 1826468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1827468a9428SGeorge Spelvin 1828468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 18292a18da7aSGeorge Spelvin /* 18302a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 18312a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 18322a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 18332a18da7aSGeorge Spelvin * and no temporaries. 18342a18da7aSGeorge Spelvin * 18352a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 18362a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 18372a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 18382a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 18392a18da7aSGeorge Spelvin * 18402a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 18412a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 18422a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 18432a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 18442a18da7aSGeorge Spelvin * 18452a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 18462a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 18472a18da7aSGeorge Spelvin * toggling any given output bit. 18482a18da7aSGeorge Spelvin * 18492a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 18502a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18512a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 18522a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 18532a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 18542a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 18552a18da7aSGeorge Spelvin * Perfect: 8192 258048 18562a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 18572a18da7aSGeorge Spelvin */ 18582a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18592a18da7aSGeorge Spelvin ( x ^= (a), \ 18602a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 18612a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 18622a18da7aSGeorge Spelvin y *= 9 ) 1863bfcfaa77SLinus Torvalds 18640fed3ac8SGeorge Spelvin /* 18652a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 18662a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 18672a18da7aSGeorge Spelvin * work done before the hash value is used. 18680fed3ac8SGeorge Spelvin */ 18692a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18700fed3ac8SGeorge Spelvin { 18712a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 18722a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 18732a18da7aSGeorge Spelvin return y >> 32; 18740fed3ac8SGeorge Spelvin } 18750fed3ac8SGeorge Spelvin 1876bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1877bfcfaa77SLinus Torvalds 18782a18da7aSGeorge Spelvin /* 18792a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 18802a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18812a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 18822a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 18832a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 18842a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 18852a18da7aSGeorge Spelvin * Perfect: 2048 31744 18862a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 18872a18da7aSGeorge Spelvin */ 18882a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18892a18da7aSGeorge Spelvin ( x ^= (a), \ 18902a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 18912a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 18922a18da7aSGeorge Spelvin y *= 9 ) 1893bfcfaa77SLinus Torvalds 18942a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18950fed3ac8SGeorge Spelvin { 18962a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 18972a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 18980fed3ac8SGeorge Spelvin } 18990fed3ac8SGeorge Spelvin 1900bfcfaa77SLinus Torvalds #endif 1901bfcfaa77SLinus Torvalds 19022a18da7aSGeorge Spelvin /* 19032a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 19042a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 19052a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 19062a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 19072a18da7aSGeorge Spelvin * finds the delimiter after the name. 19082a18da7aSGeorge Spelvin */ 19098387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 1910bfcfaa77SLinus Torvalds { 19118387ff25SLinus Torvalds unsigned long a, x = 0, y = (unsigned long)salt; 1912bfcfaa77SLinus Torvalds 1913bfcfaa77SLinus Torvalds for (;;) { 1914fcfd2fbfSGeorge Spelvin if (!len) 1915fcfd2fbfSGeorge Spelvin goto done; 1916e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1917bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1918bfcfaa77SLinus Torvalds break; 19192a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1920bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1921bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1922bfcfaa77SLinus Torvalds } 19232a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 1924bfcfaa77SLinus Torvalds done: 19252a18da7aSGeorge Spelvin return fold_hash(x, y); 1926bfcfaa77SLinus Torvalds } 1927bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1928bfcfaa77SLinus Torvalds 1929fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 19308387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 1931fcfd2fbfSGeorge Spelvin { 19328387ff25SLinus Torvalds unsigned long a = 0, x = 0, y = (unsigned long)salt; 19338387ff25SLinus Torvalds unsigned long adata, mask, len; 1934fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1935fcfd2fbfSGeorge Spelvin 19368387ff25SLinus Torvalds len = 0; 19378387ff25SLinus Torvalds goto inside; 19388387ff25SLinus Torvalds 1939fcfd2fbfSGeorge Spelvin do { 19402a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1941fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 19428387ff25SLinus Torvalds inside: 1943fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 1944fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 1945fcfd2fbfSGeorge Spelvin 1946fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 1947fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 19482a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 1949fcfd2fbfSGeorge Spelvin 19502a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1951fcfd2fbfSGeorge Spelvin } 1952fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 1953fcfd2fbfSGeorge Spelvin 1954bfcfaa77SLinus Torvalds /* 1955bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1956d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1957bfcfaa77SLinus Torvalds */ 19588387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 1959bfcfaa77SLinus Torvalds { 19608387ff25SLinus Torvalds unsigned long a = 0, b, x = 0, y = (unsigned long)salt; 19618387ff25SLinus Torvalds unsigned long adata, bdata, mask, len; 196236126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1963bfcfaa77SLinus Torvalds 19648387ff25SLinus Torvalds len = 0; 19658387ff25SLinus Torvalds goto inside; 19668387ff25SLinus Torvalds 1967bfcfaa77SLinus Torvalds do { 19682a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1969bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 19708387ff25SLinus Torvalds inside: 1971e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 197236126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 197336126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1974bfcfaa77SLinus Torvalds 197536126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 197636126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 197736126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 19782a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 197936126f8fSLinus Torvalds 19802a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1981bfcfaa77SLinus Torvalds } 1982bfcfaa77SLinus Torvalds 19832a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 1984bfcfaa77SLinus Torvalds 1985fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 19868387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 19870145acc2SLinus Torvalds { 19888387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 19890145acc2SLinus Torvalds while (len--) 1990fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 19910145acc2SLinus Torvalds return end_name_hash(hash); 19920145acc2SLinus Torvalds } 1993ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 19940145acc2SLinus Torvalds 1995fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 19968387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 1997fcfd2fbfSGeorge Spelvin { 19988387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 1999fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 2000fcfd2fbfSGeorge Spelvin 2001fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 2002e0ab7af9SGeorge Spelvin while (c) { 2003fcfd2fbfSGeorge Spelvin len++; 2004fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 2005fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 2006e0ab7af9SGeorge Spelvin } 2007fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 2008fcfd2fbfSGeorge Spelvin } 2009f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2010fcfd2fbfSGeorge Spelvin 20113ddcd056SLinus Torvalds /* 2012200e9ef7SLinus Torvalds * We know there's a real path component here of at least 2013200e9ef7SLinus Torvalds * one character. 2014200e9ef7SLinus Torvalds */ 20158387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2016200e9ef7SLinus Torvalds { 20178387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2018200e9ef7SLinus Torvalds unsigned long len = 0, c; 2019200e9ef7SLinus Torvalds 2020200e9ef7SLinus Torvalds c = (unsigned char)*name; 2021200e9ef7SLinus Torvalds do { 2022200e9ef7SLinus Torvalds len++; 2023200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2024200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2025200e9ef7SLinus Torvalds } while (c && c != '/'); 2026d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2027200e9ef7SLinus Torvalds } 2028200e9ef7SLinus Torvalds 2029bfcfaa77SLinus Torvalds #endif 2030bfcfaa77SLinus Torvalds 2031200e9ef7SLinus Torvalds /* 20321da177e4SLinus Torvalds * Name resolution. 2033ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2034ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 20351da177e4SLinus Torvalds * 2036ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2037ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 20381da177e4SLinus Torvalds */ 20396de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 20401da177e4SLinus Torvalds { 20411da177e4SLinus Torvalds int err; 20421da177e4SLinus Torvalds 20431da177e4SLinus Torvalds while (*name=='/') 20441da177e4SLinus Torvalds name++; 20451da177e4SLinus Torvalds if (!*name) 20469e18f10aSAl Viro return 0; 20471da177e4SLinus Torvalds 20481da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 20491da177e4SLinus Torvalds for(;;) { 2050d6bb3e90SLinus Torvalds u64 hash_len; 2051fe479a58SAl Viro int type; 20521da177e4SLinus Torvalds 205352094c8aSAl Viro err = may_lookup(nd); 20541da177e4SLinus Torvalds if (err) 20553595e234SAl Viro return err; 20561da177e4SLinus Torvalds 20578387ff25SLinus Torvalds hash_len = hash_name(nd->path.dentry, name); 20581da177e4SLinus Torvalds 2059fe479a58SAl Viro type = LAST_NORM; 2060d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2061fe479a58SAl Viro case 2: 2062200e9ef7SLinus Torvalds if (name[1] == '.') { 2063fe479a58SAl Viro type = LAST_DOTDOT; 206416c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 206516c2cd71SAl Viro } 2066fe479a58SAl Viro break; 2067fe479a58SAl Viro case 1: 2068fe479a58SAl Viro type = LAST_DOT; 2069fe479a58SAl Viro } 20705a202bcdSAl Viro if (likely(type == LAST_NORM)) { 20715a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 207216c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 20735a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2074a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2075da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 20765a202bcdSAl Viro if (err < 0) 20773595e234SAl Viro return err; 2078d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2079d6bb3e90SLinus Torvalds name = this.name; 20805a202bcdSAl Viro } 20815a202bcdSAl Viro } 2082fe479a58SAl Viro 2083d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2084d6bb3e90SLinus Torvalds nd->last.name = name; 20855f4a6a69SAl Viro nd->last_type = type; 20865f4a6a69SAl Viro 2087d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2088d6bb3e90SLinus Torvalds if (!*name) 2089bdf6cbf1SAl Viro goto OK; 2090200e9ef7SLinus Torvalds /* 2091200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2092200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2093200e9ef7SLinus Torvalds */ 2094200e9ef7SLinus Torvalds do { 2095d6bb3e90SLinus Torvalds name++; 2096d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 20978620c238SAl Viro if (unlikely(!*name)) { 20988620c238SAl Viro OK: 2099368ee9baSAl Viro /* pathname body, done */ 21008620c238SAl Viro if (!nd->depth) 21018620c238SAl Viro return 0; 21028620c238SAl Viro name = nd->stack[nd->depth - 1].name; 2103368ee9baSAl Viro /* trailing symlink, done */ 21048620c238SAl Viro if (!name) 21058620c238SAl Viro return 0; 21068620c238SAl Viro /* last component of nested symlink */ 21074693a547SAl Viro err = walk_component(nd, WALK_GET | WALK_PUT); 21088620c238SAl Viro } else { 21094693a547SAl Viro err = walk_component(nd, WALK_GET); 21108620c238SAl Viro } 2111ce57dfc1SAl Viro if (err < 0) 21123595e234SAl Viro return err; 2113fe479a58SAl Viro 2114ce57dfc1SAl Viro if (err) { 2115626de996SAl Viro const char *s = get_link(nd); 21165a460275SAl Viro 2117a1c83681SViresh Kumar if (IS_ERR(s)) 21183595e234SAl Viro return PTR_ERR(s); 2119172a39a0SAl Viro err = 0; 212012b09578SAl Viro if (unlikely(!s)) { 212112b09578SAl Viro /* jumped */ 2122b9ff4429SAl Viro put_link(nd); 212312b09578SAl Viro } else { 2124071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 212532cd7468SAl Viro name = s; 21269e18f10aSAl Viro continue; 212748c8b0c5SAl Viro } 212831e6b01fSNick Piggin } 212997242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 213097242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 213197242f99SAl Viro if (unlazy_walk(nd, NULL, 0)) 213297242f99SAl Viro return -ECHILD; 213397242f99SAl Viro } 21343595e234SAl Viro return -ENOTDIR; 21355f4a6a69SAl Viro } 2136ce57dfc1SAl Viro } 213797242f99SAl Viro } 21381da177e4SLinus Torvalds 2139c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 214031e6b01fSNick Piggin { 214131e6b01fSNick Piggin int retval = 0; 2142c8a53ee5SAl Viro const char *s = nd->name->name; 214331e6b01fSNick Piggin 214431e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 2145980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 214631e6b01fSNick Piggin nd->depth = 0; 21475b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2148b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2149b18825a7SDavid Howells struct inode *inode = root->d_inode; 2150fd2f7cb5SAl Viro if (*s) { 215144b1d530SMiklos Szeredi if (!d_can_lookup(root)) 2152368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 21535b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 21545b6ca027SAl Viro if (retval) 2155368ee9baSAl Viro return ERR_PTR(retval); 215673d049a4SAl Viro } 21575b6ca027SAl Viro nd->path = nd->root; 21585b6ca027SAl Viro nd->inode = inode; 21595b6ca027SAl Viro if (flags & LOOKUP_RCU) { 21608b61e74fSAl Viro rcu_read_lock(); 21615b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 21628f47a016SAl Viro nd->root_seq = nd->seq; 216348a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 21645b6ca027SAl Viro } else { 21655b6ca027SAl Viro path_get(&nd->path); 21665b6ca027SAl Viro } 2167368ee9baSAl Viro return s; 21685b6ca027SAl Viro } 21695b6ca027SAl Viro 217031e6b01fSNick Piggin nd->root.mnt = NULL; 2171248fb5b9SAl Viro nd->path.mnt = NULL; 2172248fb5b9SAl Viro nd->path.dentry = NULL; 217331e6b01fSNick Piggin 217448a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 2175fd2f7cb5SAl Viro if (*s == '/') { 21769e6697e2SAl Viro if (flags & LOOKUP_RCU) 21778b61e74fSAl Viro rcu_read_lock(); 2178e41f7d4eSAl Viro set_root(nd); 2179248fb5b9SAl Viro if (likely(!nd_jump_root(nd))) 2180ef55d917SAl Viro return s; 2181ef55d917SAl Viro nd->root.mnt = NULL; 2182ef55d917SAl Viro rcu_read_unlock(); 2183ef55d917SAl Viro return ERR_PTR(-ECHILD); 2184c8a53ee5SAl Viro } else if (nd->dfd == AT_FDCWD) { 2185e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 218631e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2187c28cc364SNick Piggin unsigned seq; 218831e6b01fSNick Piggin 21898b61e74fSAl Viro rcu_read_lock(); 219031e6b01fSNick Piggin 2191c28cc364SNick Piggin do { 2192c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 219331e6b01fSNick Piggin nd->path = fs->pwd; 2194ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2195c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2196c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2197e41f7d4eSAl Viro } else { 2198e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2199ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2200e41f7d4eSAl Viro } 2201ef55d917SAl Viro return s; 220231e6b01fSNick Piggin } else { 2203582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2204c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 220531e6b01fSNick Piggin struct dentry *dentry; 220631e6b01fSNick Piggin 22072903ff01SAl Viro if (!f.file) 2208368ee9baSAl Viro return ERR_PTR(-EBADF); 220931e6b01fSNick Piggin 22102903ff01SAl Viro dentry = f.file->f_path.dentry; 221131e6b01fSNick Piggin 2212fd2f7cb5SAl Viro if (*s) { 221344b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 22142903ff01SAl Viro fdput(f); 2215368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2216f52e0c11SAl Viro } 22172903ff01SAl Viro } 22182903ff01SAl Viro 22192903ff01SAl Viro nd->path = f.file->f_path; 2220e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 22218b61e74fSAl Viro rcu_read_lock(); 222234a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 222334a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22245590ff0dSUlrich Drepper } else { 22252903ff01SAl Viro path_get(&nd->path); 222634a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 22271da177e4SLinus Torvalds } 222834a26b99SAl Viro fdput(f); 2229368ee9baSAl Viro return s; 2230e41f7d4eSAl Viro } 22319b4a9b14SAl Viro } 22329b4a9b14SAl Viro 22333bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 223495fa25d9SAl Viro { 223595fa25d9SAl Viro const char *s; 2236fec2fa24SAl Viro int error = may_follow_link(nd); 2237deb106c6SAl Viro if (unlikely(error)) 22383bdba28bSAl Viro return ERR_PTR(error); 223995fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2240fab51e8aSAl Viro nd->stack[0].name = NULL; 22413b2e7f75SAl Viro s = get_link(nd); 2242deb106c6SAl Viro return s ? s : ""; 224395fa25d9SAl Viro } 224495fa25d9SAl Viro 2245caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2246bd92d7feSAl Viro { 2247bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2248bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2249bd92d7feSAl Viro 2250bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 2251deb106c6SAl Viro return walk_component(nd, 22524693a547SAl Viro nd->flags & LOOKUP_FOLLOW 22534693a547SAl Viro ? nd->depth 22544693a547SAl Viro ? WALK_PUT | WALK_GET 22554693a547SAl Viro : WALK_GET 22564693a547SAl Viro : 0); 2257bd92d7feSAl Viro } 2258bd92d7feSAl Viro 22599b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2260c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 22619b4a9b14SAl Viro { 2262c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2263bd92d7feSAl Viro int err; 226431e6b01fSNick Piggin 2265368ee9baSAl Viro if (IS_ERR(s)) 2266368ee9baSAl Viro return PTR_ERR(s); 22673bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 22683bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 22693bdba28bSAl Viro s = trailing_symlink(nd); 22703bdba28bSAl Viro if (IS_ERR(s)) { 22713bdba28bSAl Viro err = PTR_ERR(s); 22726d7b5aaeSAl Viro break; 2273bd92d7feSAl Viro } 2274bd92d7feSAl Viro } 22759f1fafeeSAl Viro if (!err) 22769f1fafeeSAl Viro err = complete_walk(nd); 2277bd92d7feSAl Viro 2278deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2279deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2280bd23a539SAl Viro err = -ENOTDIR; 2281625b6d10SAl Viro if (!err) { 2282625b6d10SAl Viro *path = nd->path; 2283625b6d10SAl Viro nd->path.mnt = NULL; 2284625b6d10SAl Viro nd->path.dentry = NULL; 2285625b6d10SAl Viro } 2286deb106c6SAl Viro terminate_walk(nd); 2287bd92d7feSAl Viro return err; 228831e6b01fSNick Piggin } 228931e6b01fSNick Piggin 2290625b6d10SAl Viro static int filename_lookup(int dfd, struct filename *name, unsigned flags, 22919ad1aaa6SAl Viro struct path *path, struct path *root) 2292873f1eedSJeff Layton { 2293894bc8c4SAl Viro int retval; 22949883d185SAl Viro struct nameidata nd; 2295abc9f5beSAl Viro if (IS_ERR(name)) 2296abc9f5beSAl Viro return PTR_ERR(name); 22979ad1aaa6SAl Viro if (unlikely(root)) { 22989ad1aaa6SAl Viro nd.root = *root; 22999ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 23009ad1aaa6SAl Viro } 23019883d185SAl Viro set_nameidata(&nd, dfd, name); 2302c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2303873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2304c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2305873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2306c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2307873f1eedSJeff Layton 2308873f1eedSJeff Layton if (likely(!retval)) 2309625b6d10SAl Viro audit_inode(name, path->dentry, flags & LOOKUP_PARENT); 23109883d185SAl Viro restore_nameidata(); 2311e4bd1c1aSAl Viro putname(name); 2312873f1eedSJeff Layton return retval; 2313873f1eedSJeff Layton } 2314873f1eedSJeff Layton 23158bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2316c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2317391172c4SAl Viro struct path *parent) 23188bcb77faSAl Viro { 2319c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2320368ee9baSAl Viro int err; 2321368ee9baSAl Viro if (IS_ERR(s)) 2322368ee9baSAl Viro return PTR_ERR(s); 2323368ee9baSAl Viro err = link_path_walk(s, nd); 23248bcb77faSAl Viro if (!err) 23258bcb77faSAl Viro err = complete_walk(nd); 2326391172c4SAl Viro if (!err) { 2327391172c4SAl Viro *parent = nd->path; 2328391172c4SAl Viro nd->path.mnt = NULL; 2329391172c4SAl Viro nd->path.dentry = NULL; 2330391172c4SAl Viro } 2331deb106c6SAl Viro terminate_walk(nd); 23328bcb77faSAl Viro return err; 23338bcb77faSAl Viro } 23348bcb77faSAl Viro 23355c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2336391172c4SAl Viro unsigned int flags, struct path *parent, 2337391172c4SAl Viro struct qstr *last, int *type) 23388bcb77faSAl Viro { 23398bcb77faSAl Viro int retval; 23409883d185SAl Viro struct nameidata nd; 23418bcb77faSAl Viro 23425c31b6ceSAl Viro if (IS_ERR(name)) 23435c31b6ceSAl Viro return name; 23449883d185SAl Viro set_nameidata(&nd, dfd, name); 2345c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 23468bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2347c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 23488bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2349c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2350391172c4SAl Viro if (likely(!retval)) { 2351391172c4SAl Viro *last = nd.last; 2352391172c4SAl Viro *type = nd.last_type; 2353391172c4SAl Viro audit_inode(name, parent->dentry, LOOKUP_PARENT); 23545c31b6ceSAl Viro } else { 23555c31b6ceSAl Viro putname(name); 23565c31b6ceSAl Viro name = ERR_PTR(retval); 2357391172c4SAl Viro } 23589883d185SAl Viro restore_nameidata(); 23595c31b6ceSAl Viro return name; 23608bcb77faSAl Viro } 23618bcb77faSAl Viro 236279714f72SAl Viro /* does lookup, returns the object with parent locked */ 236379714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 23645590ff0dSUlrich Drepper { 23655c31b6ceSAl Viro struct filename *filename; 23665c31b6ceSAl Viro struct dentry *d; 2367391172c4SAl Viro struct qstr last; 2368391172c4SAl Viro int type; 236951689104SPaul Moore 23705c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 23715c31b6ceSAl Viro &last, &type); 237251689104SPaul Moore if (IS_ERR(filename)) 237351689104SPaul Moore return ERR_CAST(filename); 23745c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2375391172c4SAl Viro path_put(path); 23765c31b6ceSAl Viro putname(filename); 23775c31b6ceSAl Viro return ERR_PTR(-EINVAL); 237879714f72SAl Viro } 23795955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2380391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 238179714f72SAl Viro if (IS_ERR(d)) { 23825955102cSAl Viro inode_unlock(path->dentry->d_inode); 2383391172c4SAl Viro path_put(path); 238479714f72SAl Viro } 238551689104SPaul Moore putname(filename); 238679714f72SAl Viro return d; 23875590ff0dSUlrich Drepper } 23885590ff0dSUlrich Drepper 2389d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2390d1811465SAl Viro { 2391abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2392abc9f5beSAl Viro flags, path, NULL); 2393d1811465SAl Viro } 23944d359507SAl Viro EXPORT_SYMBOL(kern_path); 2395d1811465SAl Viro 239616f18200SJosef 'Jeff' Sipek /** 239716f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 239816f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 239916f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 240016f18200SJosef 'Jeff' Sipek * @name: pointer to file name 240116f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2402e0a01249SAl Viro * @path: pointer to struct path to fill 240316f18200SJosef 'Jeff' Sipek */ 240416f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 240516f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2406e0a01249SAl Viro struct path *path) 240716f18200SJosef 'Jeff' Sipek { 24089ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 24099ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2410abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2411abc9f5beSAl Viro flags , path, &root); 241216f18200SJosef 'Jeff' Sipek } 24134d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 241416f18200SJosef 'Jeff' Sipek 2415eead1911SChristoph Hellwig /** 2416a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2417eead1911SChristoph Hellwig * @name: pathname component to lookup 2418eead1911SChristoph Hellwig * @base: base directory to lookup from 2419eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2420eead1911SChristoph Hellwig * 2421a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 24229e7543e9SAl Viro * not be called by generic code. 2423bbddca8eSNeilBrown * 2424bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2425eead1911SChristoph Hellwig */ 2426057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2427057f6c01SJames Morris { 2428057f6c01SJames Morris struct qstr this; 24296a96ba54SAl Viro unsigned int c; 2430cda309deSMiklos Szeredi int err; 2431057f6c01SJames Morris 24325955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 24332f9092e1SDavid Woodhouse 24346a96ba54SAl Viro this.name = name; 24356a96ba54SAl Viro this.len = len; 24368387ff25SLinus Torvalds this.hash = full_name_hash(base, name, len); 24376a96ba54SAl Viro if (!len) 24386a96ba54SAl Viro return ERR_PTR(-EACCES); 24396a96ba54SAl Viro 244021d8a15aSAl Viro if (unlikely(name[0] == '.')) { 244121d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 244221d8a15aSAl Viro return ERR_PTR(-EACCES); 244321d8a15aSAl Viro } 244421d8a15aSAl Viro 24456a96ba54SAl Viro while (len--) { 24466a96ba54SAl Viro c = *(const unsigned char *)name++; 24476a96ba54SAl Viro if (c == '/' || c == '\0') 24486a96ba54SAl Viro return ERR_PTR(-EACCES); 24496a96ba54SAl Viro } 24505a202bcdSAl Viro /* 24515a202bcdSAl Viro * See if the low-level filesystem might want 24525a202bcdSAl Viro * to use its own hash.. 24535a202bcdSAl Viro */ 24545a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2455da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 24565a202bcdSAl Viro if (err < 0) 24575a202bcdSAl Viro return ERR_PTR(err); 24585a202bcdSAl Viro } 2459eead1911SChristoph Hellwig 2460cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2461cda309deSMiklos Szeredi if (err) 2462cda309deSMiklos Szeredi return ERR_PTR(err); 2463cda309deSMiklos Szeredi 246472bd866aSAl Viro return __lookup_hash(&this, base, 0); 2465057f6c01SJames Morris } 24664d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2467057f6c01SJames Morris 2468bbddca8eSNeilBrown /** 2469bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2470bbddca8eSNeilBrown * @name: pathname component to lookup 2471bbddca8eSNeilBrown * @base: base directory to lookup from 2472bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2473bbddca8eSNeilBrown * 2474bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2475bbddca8eSNeilBrown * not be called by generic code. 2476bbddca8eSNeilBrown * 2477bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2478bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2479bbddca8eSNeilBrown */ 2480bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2481bbddca8eSNeilBrown struct dentry *base, int len) 2482bbddca8eSNeilBrown { 2483bbddca8eSNeilBrown struct qstr this; 2484bbddca8eSNeilBrown unsigned int c; 2485bbddca8eSNeilBrown int err; 248620d00ee8SLinus Torvalds struct dentry *ret; 2487bbddca8eSNeilBrown 2488bbddca8eSNeilBrown this.name = name; 2489bbddca8eSNeilBrown this.len = len; 24908387ff25SLinus Torvalds this.hash = full_name_hash(base, name, len); 2491bbddca8eSNeilBrown if (!len) 2492bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2493bbddca8eSNeilBrown 2494bbddca8eSNeilBrown if (unlikely(name[0] == '.')) { 2495bbddca8eSNeilBrown if (len < 2 || (len == 2 && name[1] == '.')) 2496bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2497bbddca8eSNeilBrown } 2498bbddca8eSNeilBrown 2499bbddca8eSNeilBrown while (len--) { 2500bbddca8eSNeilBrown c = *(const unsigned char *)name++; 2501bbddca8eSNeilBrown if (c == '/' || c == '\0') 2502bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2503bbddca8eSNeilBrown } 2504bbddca8eSNeilBrown /* 2505bbddca8eSNeilBrown * See if the low-level filesystem might want 2506bbddca8eSNeilBrown * to use its own hash.. 2507bbddca8eSNeilBrown */ 2508bbddca8eSNeilBrown if (base->d_flags & DCACHE_OP_HASH) { 2509bbddca8eSNeilBrown int err = base->d_op->d_hash(base, &this); 2510bbddca8eSNeilBrown if (err < 0) 2511bbddca8eSNeilBrown return ERR_PTR(err); 2512bbddca8eSNeilBrown } 2513bbddca8eSNeilBrown 2514bbddca8eSNeilBrown err = inode_permission(base->d_inode, MAY_EXEC); 2515bbddca8eSNeilBrown if (err) 2516bbddca8eSNeilBrown return ERR_PTR(err); 2517bbddca8eSNeilBrown 251820d00ee8SLinus Torvalds ret = lookup_dcache(&this, base, 0); 251920d00ee8SLinus Torvalds if (!ret) 252020d00ee8SLinus Torvalds ret = lookup_slow(&this, base, 0); 252120d00ee8SLinus Torvalds return ret; 2522bbddca8eSNeilBrown } 2523bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2524bbddca8eSNeilBrown 2525eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2526eedf265aSEric W. Biederman int path_pts(struct path *path) 2527eedf265aSEric W. Biederman { 2528eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2529eedf265aSEric W. Biederman * the input path. 2530eedf265aSEric W. Biederman */ 2531eedf265aSEric W. Biederman struct dentry *child, *parent; 2532eedf265aSEric W. Biederman struct qstr this; 2533eedf265aSEric W. Biederman int ret; 2534eedf265aSEric W. Biederman 2535eedf265aSEric W. Biederman ret = path_parent_directory(path); 2536eedf265aSEric W. Biederman if (ret) 2537eedf265aSEric W. Biederman return ret; 2538eedf265aSEric W. Biederman 2539eedf265aSEric W. Biederman parent = path->dentry; 2540eedf265aSEric W. Biederman this.name = "pts"; 2541eedf265aSEric W. Biederman this.len = 3; 2542eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2543eedf265aSEric W. Biederman if (!child) 2544eedf265aSEric W. Biederman return -ENOENT; 2545eedf265aSEric W. Biederman 2546eedf265aSEric W. Biederman path->dentry = child; 2547eedf265aSEric W. Biederman dput(parent); 2548eedf265aSEric W. Biederman follow_mount(path); 2549eedf265aSEric W. Biederman return 0; 2550eedf265aSEric W. Biederman } 2551eedf265aSEric W. Biederman #endif 2552eedf265aSEric W. Biederman 25531fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 25541fa1e7f6SAndy Whitcroft struct path *path, int *empty) 25551da177e4SLinus Torvalds { 2556abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2557abc9f5beSAl Viro flags, path, NULL); 25581da177e4SLinus Torvalds } 2559b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 25601fa1e7f6SAndy Whitcroft 2561873f1eedSJeff Layton /* 2562873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2563873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2564873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2565873f1eedSJeff Layton * path-walking is complete. 2566873f1eedSJeff Layton */ 2567a2ec4a2dSAl Viro static inline struct filename * 2568f5beed75SAl Viro user_path_parent(int dfd, const char __user *path, 2569f5beed75SAl Viro struct path *parent, 2570f5beed75SAl Viro struct qstr *last, 2571f5beed75SAl Viro int *type, 25729e790bd6SJeff Layton unsigned int flags) 25732ad94ae6SAl Viro { 25749e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 25755c31b6ceSAl Viro return filename_parentat(dfd, getname(path), flags & LOOKUP_REVAL, 25765c31b6ceSAl Viro parent, last, type); 25772ad94ae6SAl Viro } 25782ad94ae6SAl Viro 25798033426eSJeff Layton /** 2580197df04cSAl Viro * mountpoint_last - look up last component for umount 25818033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 25828033426eSJeff Layton * @path: pointer to container for result 25838033426eSJeff Layton * 25848033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 25858033426eSJeff Layton * need to resolve the path without doing any revalidation. 25868033426eSJeff Layton * 25878033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 25888033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 25898033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 25908033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 25918033426eSJeff Layton * bogus and it doesn't exist. 25928033426eSJeff Layton * 25938033426eSJeff Layton * Returns: 25948033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 25958033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 25968033426eSJeff Layton * put in this case. 25978033426eSJeff Layton * 25988033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 25998033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 26008033426eSJeff Layton * The nd->path reference will also be put. 26018033426eSJeff Layton * 26028033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 26038033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 26048033426eSJeff Layton * to the link, and nd->path will *not* be put. 26058033426eSJeff Layton */ 26068033426eSJeff Layton static int 2607197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 26088033426eSJeff Layton { 26098033426eSJeff Layton int error = 0; 26108033426eSJeff Layton struct dentry *dentry; 26118033426eSJeff Layton struct dentry *dir = nd->path.dentry; 26128033426eSJeff Layton 261335759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 261435759521SAl Viro if (nd->flags & LOOKUP_RCU) { 26156e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 2616deb106c6SAl Viro return -ECHILD; 26178033426eSJeff Layton } 26188033426eSJeff Layton 26198033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 26208033426eSJeff Layton 26218033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 26228033426eSJeff Layton error = handle_dots(nd, nd->last_type); 262335759521SAl Viro if (error) 2624deb106c6SAl Viro return error; 26258033426eSJeff Layton dentry = dget(nd->path.dentry); 2626949a852eSAl Viro } else { 26278033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 26288033426eSJeff Layton if (!dentry) { 26298033426eSJeff Layton /* 2630949a852eSAl Viro * No cached dentry. Mounted dentries are pinned in the 2631949a852eSAl Viro * cache, so that means that this dentry is probably 2632949a852eSAl Viro * a symlink or the path doesn't actually point 2633949a852eSAl Viro * to a mounted dentry. 26348033426eSJeff Layton */ 2635949a852eSAl Viro dentry = lookup_slow(&nd->last, dir, 2636949a852eSAl Viro nd->flags | LOOKUP_NO_REVAL); 2637949a852eSAl Viro if (IS_ERR(dentry)) 2638deb106c6SAl Viro return PTR_ERR(dentry); 26398033426eSJeff Layton } 2640bcceeebaSDave Jones } 2641698934dfSDavid Howells if (d_is_negative(dentry)) { 26428033426eSJeff Layton dput(dentry); 2643deb106c6SAl Viro return -ENOENT; 264435759521SAl Viro } 2645191d7f73SAl Viro if (nd->depth) 2646191d7f73SAl Viro put_link(nd); 26478033426eSJeff Layton path->dentry = dentry; 2648295dc39dSVasily Averin path->mnt = nd->path.mnt; 2649181548c0SAl Viro error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW, 2650181548c0SAl Viro d_backing_inode(dentry), 0); 2651deb106c6SAl Viro if (unlikely(error)) 2652d63ff28fSAl Viro return error; 2653295dc39dSVasily Averin mntget(path->mnt); 26548033426eSJeff Layton follow_mount(path); 2655deb106c6SAl Viro return 0; 26568033426eSJeff Layton } 26578033426eSJeff Layton 26588033426eSJeff Layton /** 2659197df04cSAl Viro * path_mountpoint - look up a path to be umounted 26602a78b857SMasanari Iida * @nd: lookup context 26618033426eSJeff Layton * @flags: lookup flags 2662c8a53ee5SAl Viro * @path: pointer to container for result 26638033426eSJeff Layton * 26648033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2665606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 26668033426eSJeff Layton */ 26678033426eSJeff Layton static int 2668c8a53ee5SAl Viro path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) 26698033426eSJeff Layton { 2670c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2671368ee9baSAl Viro int err; 2672368ee9baSAl Viro if (IS_ERR(s)) 2673368ee9baSAl Viro return PTR_ERR(s); 26743bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 26753bdba28bSAl Viro (err = mountpoint_last(nd, path)) > 0) { 26763bdba28bSAl Viro s = trailing_symlink(nd); 26773bdba28bSAl Viro if (IS_ERR(s)) { 26783bdba28bSAl Viro err = PTR_ERR(s); 26798033426eSJeff Layton break; 26808033426eSJeff Layton } 26813bdba28bSAl Viro } 2682deb106c6SAl Viro terminate_walk(nd); 26838033426eSJeff Layton return err; 26848033426eSJeff Layton } 26858033426eSJeff Layton 26862d864651SAl Viro static int 2687668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 26882d864651SAl Viro unsigned int flags) 26892d864651SAl Viro { 26909883d185SAl Viro struct nameidata nd; 2691cbaab2dbSAl Viro int error; 2692668696dcSAl Viro if (IS_ERR(name)) 2693668696dcSAl Viro return PTR_ERR(name); 26949883d185SAl Viro set_nameidata(&nd, dfd, name); 2695c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); 26962d864651SAl Viro if (unlikely(error == -ECHILD)) 2697c8a53ee5SAl Viro error = path_mountpoint(&nd, flags, path); 26982d864651SAl Viro if (unlikely(error == -ESTALE)) 2699c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); 27002d864651SAl Viro if (likely(!error)) 2701668696dcSAl Viro audit_inode(name, path->dentry, 0); 27029883d185SAl Viro restore_nameidata(); 2703668696dcSAl Viro putname(name); 27042d864651SAl Viro return error; 27052d864651SAl Viro } 27062d864651SAl Viro 27078033426eSJeff Layton /** 2708197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 27098033426eSJeff Layton * @dfd: directory file descriptor 27108033426eSJeff Layton * @name: pathname from userland 27118033426eSJeff Layton * @flags: lookup flags 27128033426eSJeff Layton * @path: pointer to container to hold result 27138033426eSJeff Layton * 27148033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 27158033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 27168033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 27178033426eSJeff Layton * and avoid revalidating the last component. 27188033426eSJeff Layton * 27198033426eSJeff Layton * Returns 0 and populates "path" on success. 27208033426eSJeff Layton */ 27218033426eSJeff Layton int 2722197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 27238033426eSJeff Layton struct path *path) 27248033426eSJeff Layton { 2725cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 27268033426eSJeff Layton } 27278033426eSJeff Layton 27282d864651SAl Viro int 27292d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 27302d864651SAl Viro unsigned int flags) 27312d864651SAl Viro { 2732cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 27332d864651SAl Viro } 27342d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 27352d864651SAl Viro 2736cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 27371da177e4SLinus Torvalds { 27388e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2739da9592edSDavid Howells 27408e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 27411da177e4SLinus Torvalds return 0; 27428e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 27431da177e4SLinus Torvalds return 0; 274423adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 27451da177e4SLinus Torvalds } 2746cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 27471da177e4SLinus Torvalds 27481da177e4SLinus Torvalds /* 27491da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 27501da177e4SLinus Torvalds * whether the type of victim is right. 27511da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 27521da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 27531da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 27541da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 27551da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 27561da177e4SLinus Torvalds * a. be owner of dir, or 27571da177e4SLinus Torvalds * b. be owner of victim, or 27581da177e4SLinus Torvalds * c. have CAP_FOWNER capability 27591da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 27601da177e4SLinus Torvalds * links pointing to it. 27610bd23d09SEric W. Biederman * 7. If the victim has an unknown uid or gid we can't change the inode. 27620bd23d09SEric W. Biederman * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. 27630bd23d09SEric W. Biederman * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. 27640bd23d09SEric W. Biederman * 10. We can't remove a root or mountpoint. 27650bd23d09SEric W. Biederman * 11. We don't allow removal of NFS sillyrenamed files; it's handled by 27661da177e4SLinus Torvalds * nfs_async_unlink(). 27671da177e4SLinus Torvalds */ 2768b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 27691da177e4SLinus Torvalds { 277063afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 27711da177e4SLinus Torvalds int error; 27721da177e4SLinus Torvalds 2773b18825a7SDavid Howells if (d_is_negative(victim)) 27741da177e4SLinus Torvalds return -ENOENT; 2775b18825a7SDavid Howells BUG_ON(!inode); 27761da177e4SLinus Torvalds 27771da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 27784fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 27791da177e4SLinus Torvalds 2780f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 27811da177e4SLinus Torvalds if (error) 27821da177e4SLinus Torvalds return error; 27831da177e4SLinus Torvalds if (IS_APPEND(dir)) 27841da177e4SLinus Torvalds return -EPERM; 2785b18825a7SDavid Howells 2786b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 27870bd23d09SEric W. Biederman IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) 27881da177e4SLinus Torvalds return -EPERM; 27891da177e4SLinus Torvalds if (isdir) { 279044b1d530SMiklos Szeredi if (!d_is_dir(victim)) 27911da177e4SLinus Torvalds return -ENOTDIR; 27921da177e4SLinus Torvalds if (IS_ROOT(victim)) 27931da177e4SLinus Torvalds return -EBUSY; 279444b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 27951da177e4SLinus Torvalds return -EISDIR; 27961da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27971da177e4SLinus Torvalds return -ENOENT; 27981da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 27991da177e4SLinus Torvalds return -EBUSY; 28001da177e4SLinus Torvalds return 0; 28011da177e4SLinus Torvalds } 28021da177e4SLinus Torvalds 28031da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 28041da177e4SLinus Torvalds * dir. 28051da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 28061da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 28071da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 2808036d5236SEric W. Biederman * 3. We can't do it if the fs can't represent the fsuid or fsgid. 2809036d5236SEric W. Biederman * 4. We should have write and exec permissions on dir 2810036d5236SEric W. Biederman * 5. We can't do it if dir is immutable (done in permission()) 28111da177e4SLinus Torvalds */ 2812a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 28131da177e4SLinus Torvalds { 2814036d5236SEric W. Biederman struct user_namespace *s_user_ns; 281514e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 28161da177e4SLinus Torvalds if (child->d_inode) 28171da177e4SLinus Torvalds return -EEXIST; 28181da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 28191da177e4SLinus Torvalds return -ENOENT; 2820036d5236SEric W. Biederman s_user_ns = dir->i_sb->s_user_ns; 2821036d5236SEric W. Biederman if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 2822036d5236SEric W. Biederman !kgid_has_mapping(s_user_ns, current_fsgid())) 2823036d5236SEric W. Biederman return -EOVERFLOW; 2824f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 28251da177e4SLinus Torvalds } 28261da177e4SLinus Torvalds 28271da177e4SLinus Torvalds /* 28281da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 28291da177e4SLinus Torvalds */ 28301da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 28311da177e4SLinus Torvalds { 28321da177e4SLinus Torvalds struct dentry *p; 28331da177e4SLinus Torvalds 28341da177e4SLinus Torvalds if (p1 == p2) { 28355955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28361da177e4SLinus Torvalds return NULL; 28371da177e4SLinus Torvalds } 28381da177e4SLinus Torvalds 2839fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 28401da177e4SLinus Torvalds 2841e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2842e2761a11SOGAWA Hirofumi if (p) { 28435955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 28445955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 28451da177e4SLinus Torvalds return p; 28461da177e4SLinus Torvalds } 28471da177e4SLinus Torvalds 2848e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2849e2761a11SOGAWA Hirofumi if (p) { 28505955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28515955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 28521da177e4SLinus Torvalds return p; 28531da177e4SLinus Torvalds } 28541da177e4SLinus Torvalds 28555955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28565955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 28571da177e4SLinus Torvalds return NULL; 28581da177e4SLinus Torvalds } 28594d359507SAl Viro EXPORT_SYMBOL(lock_rename); 28601da177e4SLinus Torvalds 28611da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 28621da177e4SLinus Torvalds { 28635955102cSAl Viro inode_unlock(p1->d_inode); 28641da177e4SLinus Torvalds if (p1 != p2) { 28655955102cSAl Viro inode_unlock(p2->d_inode); 2866fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 28671da177e4SLinus Torvalds } 28681da177e4SLinus Torvalds } 28694d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 28701da177e4SLinus Torvalds 28714acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2872312b63fbSAl Viro bool want_excl) 28731da177e4SLinus Torvalds { 2874a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28751da177e4SLinus Torvalds if (error) 28761da177e4SLinus Torvalds return error; 28771da177e4SLinus Torvalds 2878acfa4380SAl Viro if (!dir->i_op->create) 28791da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 28801da177e4SLinus Torvalds mode &= S_IALLUGO; 28811da177e4SLinus Torvalds mode |= S_IFREG; 28821da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 28831da177e4SLinus Torvalds if (error) 28841da177e4SLinus Torvalds return error; 2885312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2886a74574aaSStephen Smalley if (!error) 2887f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28881da177e4SLinus Torvalds return error; 28891da177e4SLinus Torvalds } 28904d359507SAl Viro EXPORT_SYMBOL(vfs_create); 28911da177e4SLinus Torvalds 2892a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 2893a2982cc9SEric W. Biederman { 2894a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 2895a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 2896a2982cc9SEric W. Biederman } 2897a2982cc9SEric W. Biederman 289873d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 28991da177e4SLinus Torvalds { 29003fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 29011da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 29021da177e4SLinus Torvalds int error; 29031da177e4SLinus Torvalds 29041da177e4SLinus Torvalds if (!inode) 29051da177e4SLinus Torvalds return -ENOENT; 29061da177e4SLinus Torvalds 2907c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2908c8fe8f30SChristoph Hellwig case S_IFLNK: 29091da177e4SLinus Torvalds return -ELOOP; 2910c8fe8f30SChristoph Hellwig case S_IFDIR: 2911c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 29121da177e4SLinus Torvalds return -EISDIR; 2913c8fe8f30SChristoph Hellwig break; 2914c8fe8f30SChristoph Hellwig case S_IFBLK: 2915c8fe8f30SChristoph Hellwig case S_IFCHR: 2916a2982cc9SEric W. Biederman if (!may_open_dev(path)) 29171da177e4SLinus Torvalds return -EACCES; 2918c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2919c8fe8f30SChristoph Hellwig case S_IFIFO: 2920c8fe8f30SChristoph Hellwig case S_IFSOCK: 29211da177e4SLinus Torvalds flag &= ~O_TRUNC; 2922c8fe8f30SChristoph Hellwig break; 29234a3fd211SDave Hansen } 2924b41572e9SDave Hansen 292562fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2926b41572e9SDave Hansen if (error) 2927b41572e9SDave Hansen return error; 29286146f0d5SMimi Zohar 29291da177e4SLinus Torvalds /* 29301da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 29311da177e4SLinus Torvalds */ 29321da177e4SLinus Torvalds if (IS_APPEND(inode)) { 29338737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 29347715b521SAl Viro return -EPERM; 29351da177e4SLinus Torvalds if (flag & O_TRUNC) 29367715b521SAl Viro return -EPERM; 29371da177e4SLinus Torvalds } 29381da177e4SLinus Torvalds 29391da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 29402e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 29417715b521SAl Viro return -EPERM; 29421da177e4SLinus Torvalds 2943f3c7691eSJ. Bruce Fields return 0; 29447715b521SAl Viro } 29457715b521SAl Viro 2946e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 29477715b521SAl Viro { 2948e1181ee6SJeff Layton struct path *path = &filp->f_path; 29497715b521SAl Viro struct inode *inode = path->dentry->d_inode; 29507715b521SAl Viro int error = get_write_access(inode); 29511da177e4SLinus Torvalds if (error) 29527715b521SAl Viro return error; 29531da177e4SLinus Torvalds /* 29541da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 29551da177e4SLinus Torvalds */ 2956d7a06983SJeff Layton error = locks_verify_locked(filp); 2957be6d3e56SKentaro Takeda if (!error) 2958ea0d3ab2STetsuo Handa error = security_path_truncate(path); 29591da177e4SLinus Torvalds if (!error) { 29607715b521SAl Viro error = do_truncate(path->dentry, 0, 2961d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2962e1181ee6SJeff Layton filp); 29631da177e4SLinus Torvalds } 29641da177e4SLinus Torvalds put_write_access(inode); 2965acd0c935SMimi Zohar return error; 29661da177e4SLinus Torvalds } 29671da177e4SLinus Torvalds 2968d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2969d57999e1SDave Hansen { 29708a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 29718a5e929dSAl Viro flag--; 2972d57999e1SDave Hansen return flag; 2973d57999e1SDave Hansen } 2974d57999e1SDave Hansen 2975d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 2976d18e9008SMiklos Szeredi { 2977d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2978d18e9008SMiklos Szeredi if (error) 2979d18e9008SMiklos Szeredi return error; 2980d18e9008SMiklos Szeredi 2981d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2982d18e9008SMiklos Szeredi if (error) 2983d18e9008SMiklos Szeredi return error; 2984d18e9008SMiklos Szeredi 2985d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2986d18e9008SMiklos Szeredi } 2987d18e9008SMiklos Szeredi 29881acf0af9SDavid Howells /* 29891acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 29901acf0af9SDavid Howells * dentry. 29911acf0af9SDavid Howells * 29921acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 29931acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 29941acf0af9SDavid Howells * 29951acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 29961acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 29971acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 29981acf0af9SDavid Howells * 29991acf0af9SDavid Howells * Returns an error code otherwise. 30001acf0af9SDavid Howells */ 30012675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 300230d90494SAl Viro struct path *path, struct file *file, 3003015c3bbcSMiklos Szeredi const struct open_flags *op, 30041643b43fSAl Viro int open_flag, umode_t mode, 300547237687SAl Viro int *opened) 3006d18e9008SMiklos Szeredi { 3007d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 3008d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 3009d18e9008SMiklos Szeredi int error; 3010d18e9008SMiklos Szeredi 3011384f26e2SAl Viro if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ 3012d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 3013d18e9008SMiklos Szeredi 3014d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 3015d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 3016d18e9008SMiklos Szeredi 301730d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 301830d90494SAl Viro file->f_path.mnt = nd->path.mnt; 30190fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 30200fb1ea09SAl Viro open_to_namei_flags(open_flag), 30210fb1ea09SAl Viro mode, opened); 30226fbd0714SAl Viro d_lookup_done(dentry); 3023384f26e2SAl Viro if (!error) { 3024d18e9008SMiklos Szeredi /* 3025384f26e2SAl Viro * We didn't have the inode before the open, so check open 3026384f26e2SAl Viro * permission here. 3027d18e9008SMiklos Szeredi */ 3028384f26e2SAl Viro int acc_mode = op->acc_mode; 302903da633aSAl Viro if (*opened & FILE_CREATED) { 303003da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 303103da633aSAl Viro fsnotify_create(dir, dentry); 303262fb4a15SAl Viro acc_mode = 0; 303303da633aSAl Viro } 30342675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 3035384f26e2SAl Viro if (WARN_ON(error > 0)) 3036384f26e2SAl Viro error = -EINVAL; 3037384f26e2SAl Viro } else if (error > 0) { 3038d18e9008SMiklos Szeredi if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 3039d18e9008SMiklos Szeredi error = -EIO; 3040384f26e2SAl Viro } else { 3041d18e9008SMiklos Szeredi if (file->f_path.dentry) { 3042d18e9008SMiklos Szeredi dput(dentry); 3043d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 304410c64ceaSAl Viro } 3045d18e9008SMiklos Szeredi if (*opened & FILE_CREATED) 3046d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 3047a01e718fSAl Viro if (unlikely(d_is_negative(dentry))) { 3048a01e718fSAl Viro error = -ENOENT; 3049a01e718fSAl Viro } else { 3050d18e9008SMiklos Szeredi path->dentry = dentry; 3051d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 30522675a4ebSAl Viro return 1; 3053d18e9008SMiklos Szeredi } 3054d18e9008SMiklos Szeredi } 3055a01e718fSAl Viro } 3056d18e9008SMiklos Szeredi dput(dentry); 3057d18e9008SMiklos Szeredi return error; 3058d18e9008SMiklos Szeredi } 3059d18e9008SMiklos Szeredi 306031e6b01fSNick Piggin /* 30611acf0af9SDavid Howells * Look up and maybe create and open the last component. 3062d58ffd35SMiklos Szeredi * 3063d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 3064d58ffd35SMiklos Szeredi * 30651acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 30661acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 30671acf0af9SDavid Howells * 30681acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 30691acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 30701acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 30711acf0af9SDavid Howells * specified then a negative dentry may be returned. 30721acf0af9SDavid Howells * 30731acf0af9SDavid Howells * An error code is returned otherwise. 30741acf0af9SDavid Howells * 30751acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 30761acf0af9SDavid Howells * cleared otherwise prior to returning. 3077d58ffd35SMiklos Szeredi */ 30782675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 307930d90494SAl Viro struct file *file, 3080d58ffd35SMiklos Szeredi const struct open_flags *op, 308164894cf8SAl Viro bool got_write, int *opened) 3082d58ffd35SMiklos Szeredi { 3083d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 308454ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 30851643b43fSAl Viro int open_flag = op->open_flag; 3086d58ffd35SMiklos Szeredi struct dentry *dentry; 30871643b43fSAl Viro int error, create_error = 0; 30881643b43fSAl Viro umode_t mode = op->mode; 30896fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3090d58ffd35SMiklos Szeredi 3091ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3092ce8644fcSAl Viro return -ENOENT; 3093d58ffd35SMiklos Szeredi 309447237687SAl Viro *opened &= ~FILE_CREATED; 30956fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 30966fbd0714SAl Viro for (;;) { 30976fbd0714SAl Viro if (!dentry) { 30986fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3099d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 31002675a4ebSAl Viro return PTR_ERR(dentry); 31016fbd0714SAl Viro } 31026fbd0714SAl Viro if (d_in_lookup(dentry)) 31036fbd0714SAl Viro break; 3104d58ffd35SMiklos Szeredi 31056fbd0714SAl Viro if (!(dentry->d_flags & DCACHE_OP_REVALIDATE)) 31066fbd0714SAl Viro break; 31076fbd0714SAl Viro 31086fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 31096fbd0714SAl Viro if (likely(error > 0)) 31106fbd0714SAl Viro break; 31116fbd0714SAl Viro if (error) 31126fbd0714SAl Viro goto out_dput; 31136fbd0714SAl Viro d_invalidate(dentry); 31146fbd0714SAl Viro dput(dentry); 31156fbd0714SAl Viro dentry = NULL; 31166fbd0714SAl Viro } 31176fbd0714SAl Viro if (dentry->d_inode) { 3118d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3119d18e9008SMiklos Szeredi goto out_no_open; 31206c51e513SAl Viro } 3121d18e9008SMiklos Szeredi 31221643b43fSAl Viro /* 31231643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 31241643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 31251643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 31261643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 31271643b43fSAl Viro * 31281643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 31291643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 31301643b43fSAl Viro */ 31311643b43fSAl Viro if (open_flag & O_CREAT) { 31321643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 31331643b43fSAl Viro mode &= ~current_umask(); 31341643b43fSAl Viro if (unlikely(!got_write)) { 31351643b43fSAl Viro create_error = -EROFS; 31361643b43fSAl Viro open_flag &= ~O_CREAT; 31371643b43fSAl Viro if (open_flag & (O_EXCL | O_TRUNC)) 31381643b43fSAl Viro goto no_open; 31391643b43fSAl Viro /* No side effects, safe to clear O_CREAT */ 31401643b43fSAl Viro } else { 31411643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 31421643b43fSAl Viro if (create_error) { 31431643b43fSAl Viro open_flag &= ~O_CREAT; 31441643b43fSAl Viro if (open_flag & O_EXCL) 31451643b43fSAl Viro goto no_open; 31461643b43fSAl Viro } 31471643b43fSAl Viro } 31481643b43fSAl Viro } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && 31491643b43fSAl Viro unlikely(!got_write)) { 31501643b43fSAl Viro /* 31511643b43fSAl Viro * No O_CREATE -> atomicity not a requirement -> fall 31521643b43fSAl Viro * back to lookup + open 31531643b43fSAl Viro */ 31541643b43fSAl Viro goto no_open; 3155d18e9008SMiklos Szeredi } 3156d18e9008SMiklos Szeredi 31571643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 31581643b43fSAl Viro error = atomic_open(nd, dentry, path, file, op, open_flag, 31591643b43fSAl Viro mode, opened); 31601643b43fSAl Viro if (unlikely(error == -ENOENT) && create_error) 31611643b43fSAl Viro error = create_error; 31621643b43fSAl Viro return error; 31631643b43fSAl Viro } 316454ef4872SMiklos Szeredi 31651643b43fSAl Viro no_open: 31666fbd0714SAl Viro if (d_in_lookup(dentry)) { 316712fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 316812fa5e24SAl Viro nd->flags); 31696fbd0714SAl Viro d_lookup_done(dentry); 317012fa5e24SAl Viro if (unlikely(res)) { 317112fa5e24SAl Viro if (IS_ERR(res)) { 317212fa5e24SAl Viro error = PTR_ERR(res); 317312fa5e24SAl Viro goto out_dput; 317412fa5e24SAl Viro } 317512fa5e24SAl Viro dput(dentry); 317612fa5e24SAl Viro dentry = res; 317712fa5e24SAl Viro } 317854ef4872SMiklos Szeredi } 317954ef4872SMiklos Szeredi 3180d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 31811643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 318247237687SAl Viro *opened |= FILE_CREATED; 3183ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3184ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3185ce8644fcSAl Viro error = -EACCES; 3186d58ffd35SMiklos Szeredi goto out_dput; 318777d660a8SMiklos Szeredi } 3188ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 31891643b43fSAl Viro open_flag & O_EXCL); 3190d58ffd35SMiklos Szeredi if (error) 3191d58ffd35SMiklos Szeredi goto out_dput; 3192ce8644fcSAl Viro fsnotify_create(dir_inode, dentry); 3193d58ffd35SMiklos Szeredi } 31941643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 31951643b43fSAl Viro error = create_error; 3196d58ffd35SMiklos Szeredi goto out_dput; 3197d58ffd35SMiklos Szeredi } 3198d18e9008SMiklos Szeredi out_no_open: 3199d58ffd35SMiklos Szeredi path->dentry = dentry; 3200d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 32012675a4ebSAl Viro return 1; 3202d58ffd35SMiklos Szeredi 3203d58ffd35SMiklos Szeredi out_dput: 3204d58ffd35SMiklos Szeredi dput(dentry); 32052675a4ebSAl Viro return error; 3206d58ffd35SMiklos Szeredi } 3207d58ffd35SMiklos Szeredi 3208d58ffd35SMiklos Szeredi /* 3209fe2d35ffSAl Viro * Handle the last step of open() 321031e6b01fSNick Piggin */ 3211896475d5SAl Viro static int do_last(struct nameidata *nd, 321230d90494SAl Viro struct file *file, const struct open_flags *op, 321376ae2a5aSAl Viro int *opened) 3214fb1cc555SAl Viro { 3215a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3216ca344a89SAl Viro int open_flag = op->open_flag; 321777d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 321864894cf8SAl Viro bool got_write = false; 3219bcda7652SAl Viro int acc_mode = op->acc_mode; 3220254cf582SAl Viro unsigned seq; 3221a1eb3315SMiklos Szeredi struct inode *inode; 3222896475d5SAl Viro struct path path; 322316c2cd71SAl Viro int error; 3224fb1cc555SAl Viro 3225c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3226c3e380b0SAl Viro nd->flags |= op->intent; 3227c3e380b0SAl Viro 3228bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3229fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3230deb106c6SAl Viro if (unlikely(error)) 32312675a4ebSAl Viro return error; 3232e83db167SMiklos Szeredi goto finish_open; 32331f36f774SAl Viro } 3234a2c36b45SAl Viro 3235ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3236fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3237fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3238fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3239254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 3240e9742b53SAl Viro if (likely(error > 0)) 324171574865SMiklos Szeredi goto finish_lookup; 324271574865SMiklos Szeredi 3243ce57dfc1SAl Viro if (error < 0) 3244deb106c6SAl Viro return error; 3245a1eb3315SMiklos Szeredi 324637d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 32476583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3248b6183df7SMiklos Szeredi } else { 3249fe2d35ffSAl Viro /* create side of things */ 3250a3fbbde7SAl Viro /* 3251b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3252b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3253b6183df7SMiklos Szeredi * about to look up 3254a3fbbde7SAl Viro */ 32559f1fafeeSAl Viro error = complete_walk(nd); 3256e8bb73dfSAl Viro if (error) 32572675a4ebSAl Viro return error; 3258fe2d35ffSAl Viro 325976ae2a5aSAl Viro audit_inode(nd->name, dir, LOOKUP_PARENT); 32601f36f774SAl Viro /* trailing slashes? */ 3261deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3262deb106c6SAl Viro return -EISDIR; 3263b6183df7SMiklos Szeredi } 32641f36f774SAl Viro 32659cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 326664894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 326764894cf8SAl Viro if (!error) 326864894cf8SAl Viro got_write = true; 326964894cf8SAl Viro /* 327064894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 327164894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 327264894cf8SAl Viro * dropping this one anyway. 327364894cf8SAl Viro */ 327464894cf8SAl Viro } 32759cf843e3SAl Viro if (open_flag & O_CREAT) 32765955102cSAl Viro inode_lock(dir->d_inode); 32779cf843e3SAl Viro else 32789cf843e3SAl Viro inode_lock_shared(dir->d_inode); 3279896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 32809cf843e3SAl Viro if (open_flag & O_CREAT) 32815955102cSAl Viro inode_unlock(dir->d_inode); 32829cf843e3SAl Viro else 32839cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3284fb1cc555SAl Viro 32852675a4ebSAl Viro if (error <= 0) { 32862675a4ebSAl Viro if (error) 3287d58ffd35SMiklos Szeredi goto out; 32886c0d46c4SAl Viro 328947237687SAl Viro if ((*opened & FILE_CREATED) || 3290496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 329177d660a8SMiklos Szeredi will_truncate = false; 3292d18e9008SMiklos Szeredi 329376ae2a5aSAl Viro audit_inode(nd->name, file->f_path.dentry, 0); 3294d18e9008SMiklos Szeredi goto opened; 3295d18e9008SMiklos Szeredi } 3296d18e9008SMiklos Szeredi 329747237687SAl Viro if (*opened & FILE_CREATED) { 32989b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3299ca344a89SAl Viro open_flag &= ~O_TRUNC; 330077d660a8SMiklos Szeredi will_truncate = false; 330162fb4a15SAl Viro acc_mode = 0; 3302896475d5SAl Viro path_to_nameidata(&path, nd); 3303e83db167SMiklos Szeredi goto finish_open_created; 3304fb1cc555SAl Viro } 3305fb1cc555SAl Viro 3306fb1cc555SAl Viro /* 3307d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3308d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3309d18e9008SMiklos Szeredi * necessary...) 3310d18e9008SMiklos Szeredi */ 331164894cf8SAl Viro if (got_write) { 3312d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 331364894cf8SAl Viro got_write = false; 3314d18e9008SMiklos Szeredi } 3315d18e9008SMiklos Szeredi 3316e6ec03a2SAl Viro error = follow_managed(&path, nd); 3317e6ec03a2SAl Viro if (unlikely(error < 0)) 3318e6ec03a2SAl Viro return error; 3319e6ec03a2SAl Viro 33206583fe22SAl Viro if (unlikely(d_is_negative(path.dentry))) { 33216583fe22SAl Viro path_to_nameidata(&path, nd); 33226583fe22SAl Viro return -ENOENT; 33236583fe22SAl Viro } 33246583fe22SAl Viro 33256583fe22SAl Viro /* 33266583fe22SAl Viro * create/update audit record if it already exists. 33276583fe22SAl Viro */ 33286583fe22SAl Viro audit_inode(nd->name, path.dentry, 0); 33296583fe22SAl Viro 3330deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3331deb106c6SAl Viro path_to_nameidata(&path, nd); 3332deb106c6SAl Viro return -EEXIST; 3333deb106c6SAl Viro } 3334fb1cc555SAl Viro 3335254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3336d4565649SAl Viro inode = d_backing_inode(path.dentry); 3337766c4cbfSAl Viro finish_lookup: 3338191d7f73SAl Viro if (nd->depth) 3339191d7f73SAl Viro put_link(nd); 3340181548c0SAl Viro error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW, 3341181548c0SAl Viro inode, seq); 3342deb106c6SAl Viro if (unlikely(error)) 3343d63ff28fSAl Viro return error; 3344fb1cc555SAl Viro 3345896475d5SAl Viro path_to_nameidata(&path, nd); 3346decf3400SMiklos Szeredi nd->inode = inode; 3347254cf582SAl Viro nd->seq = seq; 3348a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3349bc77daa7SAl Viro finish_open: 3350a3fbbde7SAl Viro error = complete_walk(nd); 3351fac7d191SAl Viro if (error) 33522675a4ebSAl Viro return error; 335376ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 3354fb1cc555SAl Viro error = -EISDIR; 335544b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 33562675a4ebSAl Viro goto out; 3357af2f5542SMiklos Szeredi error = -ENOTDIR; 335844b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 33592675a4ebSAl Viro goto out; 33604bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 336177d660a8SMiklos Szeredi will_truncate = false; 33626c0d46c4SAl Viro 33630f9d1a10SAl Viro if (will_truncate) { 33640f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 33650f9d1a10SAl Viro if (error) 33662675a4ebSAl Viro goto out; 336764894cf8SAl Viro got_write = true; 33680f9d1a10SAl Viro } 3369e83db167SMiklos Szeredi finish_open_created: 3370bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3371ca344a89SAl Viro if (error) 33722675a4ebSAl Viro goto out; 33734aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 33744aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 3375fac7d191SAl Viro if (error) 3376015c3bbcSMiklos Szeredi goto out; 3377fac7d191SAl Viro *opened |= FILE_OPENED; 3378a8277b9bSMiklos Szeredi opened: 33792675a4ebSAl Viro error = open_check_o_direct(file); 3380fe9ec829SAl Viro if (!error) 33813034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3382fe9ec829SAl Viro if (!error && will_truncate) 33832675a4ebSAl Viro error = handle_truncate(file); 3384ca344a89SAl Viro out: 3385fe9ec829SAl Viro if (unlikely(error) && (*opened & FILE_OPENED)) 3386fe9ec829SAl Viro fput(file); 3387c80567c8SAl Viro if (unlikely(error > 0)) { 3388c80567c8SAl Viro WARN_ON(1); 3389c80567c8SAl Viro error = -EINVAL; 3390c80567c8SAl Viro } 339164894cf8SAl Viro if (got_write) 33920f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 33932675a4ebSAl Viro return error; 3394fb1cc555SAl Viro } 3395fb1cc555SAl Viro 3396c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 339760545d0dSAl Viro const struct open_flags *op, 339860545d0dSAl Viro struct file *file, int *opened) 339960545d0dSAl Viro { 340060545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 3401625b6d10SAl Viro struct dentry *child; 340260545d0dSAl Viro struct inode *dir; 3403625b6d10SAl Viro struct path path; 3404c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 340560545d0dSAl Viro if (unlikely(error)) 340660545d0dSAl Viro return error; 3407625b6d10SAl Viro error = mnt_want_write(path.mnt); 340860545d0dSAl Viro if (unlikely(error)) 340960545d0dSAl Viro goto out; 3410625b6d10SAl Viro dir = path.dentry->d_inode; 341160545d0dSAl Viro /* we want directory to be writable */ 3412625b6d10SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 341360545d0dSAl Viro if (error) 341460545d0dSAl Viro goto out2; 341560545d0dSAl Viro if (!dir->i_op->tmpfile) { 341660545d0dSAl Viro error = -EOPNOTSUPP; 341760545d0dSAl Viro goto out2; 341860545d0dSAl Viro } 3419625b6d10SAl Viro child = d_alloc(path.dentry, &name); 342060545d0dSAl Viro if (unlikely(!child)) { 342160545d0dSAl Viro error = -ENOMEM; 342260545d0dSAl Viro goto out2; 342360545d0dSAl Viro } 3424625b6d10SAl Viro dput(path.dentry); 3425625b6d10SAl Viro path.dentry = child; 3426625b6d10SAl Viro error = dir->i_op->tmpfile(dir, child, op->mode); 342760545d0dSAl Viro if (error) 342860545d0dSAl Viro goto out2; 3429c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 343069a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 343162fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 343260545d0dSAl Viro if (error) 343360545d0dSAl Viro goto out2; 3434625b6d10SAl Viro file->f_path.mnt = path.mnt; 3435625b6d10SAl Viro error = finish_open(file, child, NULL, opened); 343660545d0dSAl Viro if (error) 343760545d0dSAl Viro goto out2; 343860545d0dSAl Viro error = open_check_o_direct(file); 3439f4e0c30cSAl Viro if (error) { 344060545d0dSAl Viro fput(file); 3441f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3442f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3443f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3444f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3445f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3446f4e0c30cSAl Viro } 344760545d0dSAl Viro out2: 3448625b6d10SAl Viro mnt_drop_write(path.mnt); 344960545d0dSAl Viro out: 3450625b6d10SAl Viro path_put(&path); 345160545d0dSAl Viro return error; 345260545d0dSAl Viro } 345360545d0dSAl Viro 34546ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 34556ac08709SAl Viro { 34566ac08709SAl Viro struct path path; 34576ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 34586ac08709SAl Viro if (!error) { 34596ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 34606ac08709SAl Viro error = vfs_open(&path, file, current_cred()); 34616ac08709SAl Viro path_put(&path); 34626ac08709SAl Viro } 34636ac08709SAl Viro return error; 34646ac08709SAl Viro } 34656ac08709SAl Viro 3466c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3467c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 34681da177e4SLinus Torvalds { 3469368ee9baSAl Viro const char *s; 347030d90494SAl Viro struct file *file; 347147237687SAl Viro int opened = 0; 347213aab428SAl Viro int error; 347331e6b01fSNick Piggin 347430d90494SAl Viro file = get_empty_filp(); 34751afc99beSAl Viro if (IS_ERR(file)) 34761afc99beSAl Viro return file; 347731e6b01fSNick Piggin 347830d90494SAl Viro file->f_flags = op->open_flag; 347931e6b01fSNick Piggin 3480bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 3481c8a53ee5SAl Viro error = do_tmpfile(nd, flags, op, file, &opened); 3482f15133dfSAl Viro goto out2; 348360545d0dSAl Viro } 348460545d0dSAl Viro 34856ac08709SAl Viro if (unlikely(file->f_flags & O_PATH)) { 34866ac08709SAl Viro error = do_o_path(nd, flags, file); 34876ac08709SAl Viro if (!error) 34886ac08709SAl Viro opened |= FILE_OPENED; 34896ac08709SAl Viro goto out2; 34906ac08709SAl Viro } 34916ac08709SAl Viro 3492c8a53ee5SAl Viro s = path_init(nd, flags); 3493368ee9baSAl Viro if (IS_ERR(s)) { 3494368ee9baSAl Viro put_filp(file); 3495368ee9baSAl Viro return ERR_CAST(s); 3496368ee9baSAl Viro } 34973bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 349876ae2a5aSAl Viro (error = do_last(nd, file, op, &opened)) > 0) { 349973d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 35003bdba28bSAl Viro s = trailing_symlink(nd); 35013bdba28bSAl Viro if (IS_ERR(s)) { 35023bdba28bSAl Viro error = PTR_ERR(s); 35032675a4ebSAl Viro break; 3504806b681cSAl Viro } 35053bdba28bSAl Viro } 3506deb106c6SAl Viro terminate_walk(nd); 3507f15133dfSAl Viro out2: 35082675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 35092675a4ebSAl Viro BUG_ON(!error); 351030d90494SAl Viro put_filp(file); 3511015c3bbcSMiklos Szeredi } 35122675a4ebSAl Viro if (unlikely(error)) { 35132675a4ebSAl Viro if (error == -EOPENSTALE) { 35142675a4ebSAl Viro if (flags & LOOKUP_RCU) 35152675a4ebSAl Viro error = -ECHILD; 35162675a4ebSAl Viro else 35172675a4ebSAl Viro error = -ESTALE; 35182675a4ebSAl Viro } 35192675a4ebSAl Viro file = ERR_PTR(error); 35202675a4ebSAl Viro } 35212675a4ebSAl Viro return file; 3522de459215SKirill Korotaev } 35231da177e4SLinus Torvalds 3524669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3525f9652e10SAl Viro const struct open_flags *op) 352613aab428SAl Viro { 35279883d185SAl Viro struct nameidata nd; 3528f9652e10SAl Viro int flags = op->lookup_flags; 352913aab428SAl Viro struct file *filp; 353013aab428SAl Viro 35319883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3532c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 353313aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3534c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 353513aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3536c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 35379883d185SAl Viro restore_nameidata(); 353813aab428SAl Viro return filp; 353913aab428SAl Viro } 354013aab428SAl Viro 354173d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3542f9652e10SAl Viro const char *name, const struct open_flags *op) 354373d049a4SAl Viro { 35449883d185SAl Viro struct nameidata nd; 354573d049a4SAl Viro struct file *file; 354651689104SPaul Moore struct filename *filename; 3547f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 354873d049a4SAl Viro 354973d049a4SAl Viro nd.root.mnt = mnt; 355073d049a4SAl Viro nd.root.dentry = dentry; 355173d049a4SAl Viro 3552b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 355373d049a4SAl Viro return ERR_PTR(-ELOOP); 355473d049a4SAl Viro 355551689104SPaul Moore filename = getname_kernel(name); 3556a1c83681SViresh Kumar if (IS_ERR(filename)) 355751689104SPaul Moore return ERR_CAST(filename); 355851689104SPaul Moore 35599883d185SAl Viro set_nameidata(&nd, -1, filename); 3560c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 356173d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3562c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 356373d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3564c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 35659883d185SAl Viro restore_nameidata(); 356651689104SPaul Moore putname(filename); 356773d049a4SAl Viro return file; 356873d049a4SAl Viro } 356973d049a4SAl Viro 3570fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 35711ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 35721da177e4SLinus Torvalds { 3573c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3574391172c4SAl Viro struct qstr last; 3575391172c4SAl Viro int type; 3576c30dabfeSJan Kara int err2; 35771ac12b4bSJeff Layton int error; 35781ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 35791ac12b4bSJeff Layton 35801ac12b4bSJeff Layton /* 35811ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 35821ac12b4bSJeff Layton * other flags passed in are ignored! 35831ac12b4bSJeff Layton */ 35841ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 35851ac12b4bSJeff Layton 35865c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 35875c31b6ceSAl Viro if (IS_ERR(name)) 35885c31b6ceSAl Viro return ERR_CAST(name); 35891da177e4SLinus Torvalds 3590c663e5d8SChristoph Hellwig /* 3591c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3592c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3593c663e5d8SChristoph Hellwig */ 35945c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3595ed75e95dSAl Viro goto out; 3596c663e5d8SChristoph Hellwig 3597c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3598391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3599c663e5d8SChristoph Hellwig /* 3600c663e5d8SChristoph Hellwig * Do the final lookup. 3601c663e5d8SChristoph Hellwig */ 3602391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 36035955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3604391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 36051da177e4SLinus Torvalds if (IS_ERR(dentry)) 3606a8104a9fSAl Viro goto unlock; 3607c663e5d8SChristoph Hellwig 3608a8104a9fSAl Viro error = -EEXIST; 3609b18825a7SDavid Howells if (d_is_positive(dentry)) 3610a8104a9fSAl Viro goto fail; 3611b18825a7SDavid Howells 3612c663e5d8SChristoph Hellwig /* 3613c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3614c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3615c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3616c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3617c663e5d8SChristoph Hellwig */ 3618391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3619a8104a9fSAl Viro error = -ENOENT; 3620ed75e95dSAl Viro goto fail; 3621e9baf6e5SAl Viro } 3622c30dabfeSJan Kara if (unlikely(err2)) { 3623c30dabfeSJan Kara error = err2; 3624a8104a9fSAl Viro goto fail; 3625c30dabfeSJan Kara } 3626181c37b6SAl Viro putname(name); 3627e9baf6e5SAl Viro return dentry; 36281da177e4SLinus Torvalds fail: 3629a8104a9fSAl Viro dput(dentry); 3630a8104a9fSAl Viro dentry = ERR_PTR(error); 3631a8104a9fSAl Viro unlock: 36325955102cSAl Viro inode_unlock(path->dentry->d_inode); 3633c30dabfeSJan Kara if (!err2) 3634391172c4SAl Viro mnt_drop_write(path->mnt); 3635ed75e95dSAl Viro out: 3636391172c4SAl Viro path_put(path); 3637181c37b6SAl Viro putname(name); 3638ed75e95dSAl Viro return dentry; 3639dae6ad8fSAl Viro } 3640fa14a0b8SAl Viro 3641fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3642fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3643fa14a0b8SAl Viro { 3644181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3645181c37b6SAl Viro path, lookup_flags); 3646fa14a0b8SAl Viro } 3647dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3648dae6ad8fSAl Viro 3649921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3650921a1650SAl Viro { 3651921a1650SAl Viro dput(dentry); 36525955102cSAl Viro inode_unlock(path->dentry->d_inode); 3653a8104a9fSAl Viro mnt_drop_write(path->mnt); 3654921a1650SAl Viro path_put(path); 3655921a1650SAl Viro } 3656921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3657921a1650SAl Viro 3658520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 36591ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3660dae6ad8fSAl Viro { 3661181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3662dae6ad8fSAl Viro } 3663dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3664dae6ad8fSAl Viro 36651a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 36661da177e4SLinus Torvalds { 3667a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36681da177e4SLinus Torvalds 36691da177e4SLinus Torvalds if (error) 36701da177e4SLinus Torvalds return error; 36711da177e4SLinus Torvalds 3672975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 36731da177e4SLinus Torvalds return -EPERM; 36741da177e4SLinus Torvalds 3675acfa4380SAl Viro if (!dir->i_op->mknod) 36761da177e4SLinus Torvalds return -EPERM; 36771da177e4SLinus Torvalds 367808ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 367908ce5f16SSerge E. Hallyn if (error) 368008ce5f16SSerge E. Hallyn return error; 368108ce5f16SSerge E. Hallyn 36821da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 36831da177e4SLinus Torvalds if (error) 36841da177e4SLinus Torvalds return error; 36851da177e4SLinus Torvalds 36861da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3687a74574aaSStephen Smalley if (!error) 3688f38aa942SAmy Griffis fsnotify_create(dir, dentry); 36891da177e4SLinus Torvalds return error; 36901da177e4SLinus Torvalds } 36914d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 36921da177e4SLinus Torvalds 3693f69aac00SAl Viro static int may_mknod(umode_t mode) 3694463c3197SDave Hansen { 3695463c3197SDave Hansen switch (mode & S_IFMT) { 3696463c3197SDave Hansen case S_IFREG: 3697463c3197SDave Hansen case S_IFCHR: 3698463c3197SDave Hansen case S_IFBLK: 3699463c3197SDave Hansen case S_IFIFO: 3700463c3197SDave Hansen case S_IFSOCK: 3701463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3702463c3197SDave Hansen return 0; 3703463c3197SDave Hansen case S_IFDIR: 3704463c3197SDave Hansen return -EPERM; 3705463c3197SDave Hansen default: 3706463c3197SDave Hansen return -EINVAL; 3707463c3197SDave Hansen } 3708463c3197SDave Hansen } 3709463c3197SDave Hansen 37108208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 37112e4d0924SHeiko Carstens unsigned, dev) 37121da177e4SLinus Torvalds { 37131da177e4SLinus Torvalds struct dentry *dentry; 3714dae6ad8fSAl Viro struct path path; 3715dae6ad8fSAl Viro int error; 3716972567f1SJeff Layton unsigned int lookup_flags = 0; 37171da177e4SLinus Torvalds 37188e4bfca1SAl Viro error = may_mknod(mode); 37198e4bfca1SAl Viro if (error) 37208e4bfca1SAl Viro return error; 3721972567f1SJeff Layton retry: 3722972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3723dae6ad8fSAl Viro if (IS_ERR(dentry)) 3724dae6ad8fSAl Viro return PTR_ERR(dentry); 37252ad94ae6SAl Viro 3726dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3727ce3b0f8dSAl Viro mode &= ~current_umask(); 3728dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3729be6d3e56SKentaro Takeda if (error) 3730a8104a9fSAl Viro goto out; 37311da177e4SLinus Torvalds switch (mode & S_IFMT) { 37321da177e4SLinus Torvalds case 0: case S_IFREG: 3733312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 373405d1a717SMimi Zohar if (!error) 373505d1a717SMimi Zohar ima_post_path_mknod(dentry); 37361da177e4SLinus Torvalds break; 37371da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3738dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 37391da177e4SLinus Torvalds new_decode_dev(dev)); 37401da177e4SLinus Torvalds break; 37411da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3742dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 37431da177e4SLinus Torvalds break; 37441da177e4SLinus Torvalds } 3745a8104a9fSAl Viro out: 3746921a1650SAl Viro done_path_create(&path, dentry); 3747972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3748972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3749972567f1SJeff Layton goto retry; 3750972567f1SJeff Layton } 37511da177e4SLinus Torvalds return error; 37521da177e4SLinus Torvalds } 37531da177e4SLinus Torvalds 37548208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 37555590ff0dSUlrich Drepper { 37565590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 37575590ff0dSUlrich Drepper } 37585590ff0dSUlrich Drepper 375918bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 37601da177e4SLinus Torvalds { 3761a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 37628de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 37631da177e4SLinus Torvalds 37641da177e4SLinus Torvalds if (error) 37651da177e4SLinus Torvalds return error; 37661da177e4SLinus Torvalds 3767acfa4380SAl Viro if (!dir->i_op->mkdir) 37681da177e4SLinus Torvalds return -EPERM; 37691da177e4SLinus Torvalds 37701da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 37711da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 37721da177e4SLinus Torvalds if (error) 37731da177e4SLinus Torvalds return error; 37741da177e4SLinus Torvalds 37758de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 37768de52778SAl Viro return -EMLINK; 37778de52778SAl Viro 37781da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3779a74574aaSStephen Smalley if (!error) 3780f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 37811da177e4SLinus Torvalds return error; 37821da177e4SLinus Torvalds } 37834d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 37841da177e4SLinus Torvalds 3785a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 37861da177e4SLinus Torvalds { 37876902d925SDave Hansen struct dentry *dentry; 3788dae6ad8fSAl Viro struct path path; 3789dae6ad8fSAl Viro int error; 3790b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 37911da177e4SLinus Torvalds 3792b76d8b82SJeff Layton retry: 3793b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 37946902d925SDave Hansen if (IS_ERR(dentry)) 3795dae6ad8fSAl Viro return PTR_ERR(dentry); 37966902d925SDave Hansen 3797dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3798ce3b0f8dSAl Viro mode &= ~current_umask(); 3799dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3800a8104a9fSAl Viro if (!error) 3801dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3802921a1650SAl Viro done_path_create(&path, dentry); 3803b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3804b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3805b76d8b82SJeff Layton goto retry; 3806b76d8b82SJeff Layton } 38071da177e4SLinus Torvalds return error; 38081da177e4SLinus Torvalds } 38091da177e4SLinus Torvalds 3810a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 38115590ff0dSUlrich Drepper { 38125590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 38135590ff0dSUlrich Drepper } 38145590ff0dSUlrich Drepper 38151da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 38161da177e4SLinus Torvalds { 38171da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 38181da177e4SLinus Torvalds 38191da177e4SLinus Torvalds if (error) 38201da177e4SLinus Torvalds return error; 38211da177e4SLinus Torvalds 3822acfa4380SAl Viro if (!dir->i_op->rmdir) 38231da177e4SLinus Torvalds return -EPERM; 38241da177e4SLinus Torvalds 38251d2ef590SAl Viro dget(dentry); 38265955102cSAl Viro inode_lock(dentry->d_inode); 3827912dbc15SSage Weil 38281da177e4SLinus Torvalds error = -EBUSY; 38297af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3830912dbc15SSage Weil goto out; 3831912dbc15SSage Weil 38321da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3833912dbc15SSage Weil if (error) 3834912dbc15SSage Weil goto out; 3835912dbc15SSage Weil 38363cebde24SSage Weil shrink_dcache_parent(dentry); 38371da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3838912dbc15SSage Weil if (error) 3839912dbc15SSage Weil goto out; 3840912dbc15SSage Weil 38411da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3842d83c49f3SAl Viro dont_mount(dentry); 38438ed936b5SEric W. Biederman detach_mounts(dentry); 38441da177e4SLinus Torvalds 3845912dbc15SSage Weil out: 38465955102cSAl Viro inode_unlock(dentry->d_inode); 38471d2ef590SAl Viro dput(dentry); 3848912dbc15SSage Weil if (!error) 3849912dbc15SSage Weil d_delete(dentry); 38501da177e4SLinus Torvalds return error; 38511da177e4SLinus Torvalds } 38524d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 38531da177e4SLinus Torvalds 38545590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 38551da177e4SLinus Torvalds { 38561da177e4SLinus Torvalds int error = 0; 385791a27b2aSJeff Layton struct filename *name; 38581da177e4SLinus Torvalds struct dentry *dentry; 3859f5beed75SAl Viro struct path path; 3860f5beed75SAl Viro struct qstr last; 3861f5beed75SAl Viro int type; 3862c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3863c6ee9206SJeff Layton retry: 3864f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3865f5beed75SAl Viro &path, &last, &type, lookup_flags); 386691a27b2aSJeff Layton if (IS_ERR(name)) 386791a27b2aSJeff Layton return PTR_ERR(name); 38681da177e4SLinus Torvalds 3869f5beed75SAl Viro switch (type) { 38701da177e4SLinus Torvalds case LAST_DOTDOT: 38711da177e4SLinus Torvalds error = -ENOTEMPTY; 38721da177e4SLinus Torvalds goto exit1; 38731da177e4SLinus Torvalds case LAST_DOT: 38741da177e4SLinus Torvalds error = -EINVAL; 38751da177e4SLinus Torvalds goto exit1; 38761da177e4SLinus Torvalds case LAST_ROOT: 38771da177e4SLinus Torvalds error = -EBUSY; 38781da177e4SLinus Torvalds goto exit1; 38791da177e4SLinus Torvalds } 38800612d9fbSOGAWA Hirofumi 3881f5beed75SAl Viro error = mnt_want_write(path.mnt); 3882c30dabfeSJan Kara if (error) 3883c30dabfeSJan Kara goto exit1; 38840612d9fbSOGAWA Hirofumi 38855955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3886f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38871da177e4SLinus Torvalds error = PTR_ERR(dentry); 38886902d925SDave Hansen if (IS_ERR(dentry)) 38896902d925SDave Hansen goto exit2; 3890e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3891e6bc45d6STheodore Ts'o error = -ENOENT; 3892e6bc45d6STheodore Ts'o goto exit3; 3893e6bc45d6STheodore Ts'o } 3894f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3895be6d3e56SKentaro Takeda if (error) 3896c30dabfeSJan Kara goto exit3; 3897f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 38980622753bSDave Hansen exit3: 38991da177e4SLinus Torvalds dput(dentry); 39006902d925SDave Hansen exit2: 39015955102cSAl Viro inode_unlock(path.dentry->d_inode); 3902f5beed75SAl Viro mnt_drop_write(path.mnt); 39031da177e4SLinus Torvalds exit1: 3904f5beed75SAl Viro path_put(&path); 39051da177e4SLinus Torvalds putname(name); 3906c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3907c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3908c6ee9206SJeff Layton goto retry; 3909c6ee9206SJeff Layton } 39101da177e4SLinus Torvalds return error; 39111da177e4SLinus Torvalds } 39121da177e4SLinus Torvalds 39133cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 39145590ff0dSUlrich Drepper { 39155590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 39165590ff0dSUlrich Drepper } 39175590ff0dSUlrich Drepper 3918b21996e3SJ. Bruce Fields /** 3919b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3920b21996e3SJ. Bruce Fields * @dir: parent directory 3921b21996e3SJ. Bruce Fields * @dentry: victim 3922b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3923b21996e3SJ. Bruce Fields * 3924b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3925b21996e3SJ. Bruce Fields * 3926b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3927b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3928b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3929b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3930b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3931b21996e3SJ. Bruce Fields * 3932b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3933b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3934b21996e3SJ. Bruce Fields * to be NFS exported. 3935b21996e3SJ. Bruce Fields */ 3936b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 39371da177e4SLinus Torvalds { 39389accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 39391da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 39401da177e4SLinus Torvalds 39411da177e4SLinus Torvalds if (error) 39421da177e4SLinus Torvalds return error; 39431da177e4SLinus Torvalds 3944acfa4380SAl Viro if (!dir->i_op->unlink) 39451da177e4SLinus Torvalds return -EPERM; 39461da177e4SLinus Torvalds 39475955102cSAl Viro inode_lock(target); 39488ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 39491da177e4SLinus Torvalds error = -EBUSY; 39501da177e4SLinus Torvalds else { 39511da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3952bec1052eSAl Viro if (!error) { 39535a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 39545a14696cSJ. Bruce Fields if (error) 3955b21996e3SJ. Bruce Fields goto out; 39561da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 39578ed936b5SEric W. Biederman if (!error) { 3958d83c49f3SAl Viro dont_mount(dentry); 39598ed936b5SEric W. Biederman detach_mounts(dentry); 39608ed936b5SEric W. Biederman } 3961bec1052eSAl Viro } 39621da177e4SLinus Torvalds } 3963b21996e3SJ. Bruce Fields out: 39645955102cSAl Viro inode_unlock(target); 39651da177e4SLinus Torvalds 39661da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 39671da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 39689accbb97SJ. Bruce Fields fsnotify_link_count(target); 39691da177e4SLinus Torvalds d_delete(dentry); 39701da177e4SLinus Torvalds } 39710eeca283SRobert Love 39721da177e4SLinus Torvalds return error; 39731da177e4SLinus Torvalds } 39744d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 39751da177e4SLinus Torvalds 39761da177e4SLinus Torvalds /* 39771da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 39781b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 39791da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 39801da177e4SLinus Torvalds * while waiting on the I/O. 39811da177e4SLinus Torvalds */ 39825590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 39831da177e4SLinus Torvalds { 39842ad94ae6SAl Viro int error; 398591a27b2aSJeff Layton struct filename *name; 39861da177e4SLinus Torvalds struct dentry *dentry; 3987f5beed75SAl Viro struct path path; 3988f5beed75SAl Viro struct qstr last; 3989f5beed75SAl Viro int type; 39901da177e4SLinus Torvalds struct inode *inode = NULL; 3991b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 39925d18f813SJeff Layton unsigned int lookup_flags = 0; 39935d18f813SJeff Layton retry: 3994f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3995f5beed75SAl Viro &path, &last, &type, lookup_flags); 399691a27b2aSJeff Layton if (IS_ERR(name)) 399791a27b2aSJeff Layton return PTR_ERR(name); 39982ad94ae6SAl Viro 39991da177e4SLinus Torvalds error = -EISDIR; 4000f5beed75SAl Viro if (type != LAST_NORM) 40011da177e4SLinus Torvalds goto exit1; 40020612d9fbSOGAWA Hirofumi 4003f5beed75SAl Viro error = mnt_want_write(path.mnt); 4004c30dabfeSJan Kara if (error) 4005c30dabfeSJan Kara goto exit1; 4006b21996e3SJ. Bruce Fields retry_deleg: 40075955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 4008f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 40091da177e4SLinus Torvalds error = PTR_ERR(dentry); 40101da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 40111da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 4012f5beed75SAl Viro if (last.name[last.len]) 401350338b88STörök Edwin goto slashes; 40141da177e4SLinus Torvalds inode = dentry->d_inode; 4015b18825a7SDavid Howells if (d_is_negative(dentry)) 4016e6bc45d6STheodore Ts'o goto slashes; 40177de9c6eeSAl Viro ihold(inode); 4018f5beed75SAl Viro error = security_path_unlink(&path, dentry); 4019be6d3e56SKentaro Takeda if (error) 4020c30dabfeSJan Kara goto exit2; 4021f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 40221da177e4SLinus Torvalds exit2: 40231da177e4SLinus Torvalds dput(dentry); 40241da177e4SLinus Torvalds } 40255955102cSAl Viro inode_unlock(path.dentry->d_inode); 40261da177e4SLinus Torvalds if (inode) 40271da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 4028b21996e3SJ. Bruce Fields inode = NULL; 4029b21996e3SJ. Bruce Fields if (delegated_inode) { 40305a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4031b21996e3SJ. Bruce Fields if (!error) 4032b21996e3SJ. Bruce Fields goto retry_deleg; 4033b21996e3SJ. Bruce Fields } 4034f5beed75SAl Viro mnt_drop_write(path.mnt); 40351da177e4SLinus Torvalds exit1: 4036f5beed75SAl Viro path_put(&path); 40371da177e4SLinus Torvalds putname(name); 40385d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 40395d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 40405d18f813SJeff Layton inode = NULL; 40415d18f813SJeff Layton goto retry; 40425d18f813SJeff Layton } 40431da177e4SLinus Torvalds return error; 40441da177e4SLinus Torvalds 40451da177e4SLinus Torvalds slashes: 4046b18825a7SDavid Howells if (d_is_negative(dentry)) 4047b18825a7SDavid Howells error = -ENOENT; 404844b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 4049b18825a7SDavid Howells error = -EISDIR; 4050b18825a7SDavid Howells else 4051b18825a7SDavid Howells error = -ENOTDIR; 40521da177e4SLinus Torvalds goto exit2; 40531da177e4SLinus Torvalds } 40541da177e4SLinus Torvalds 40552e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 40565590ff0dSUlrich Drepper { 40575590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 40585590ff0dSUlrich Drepper return -EINVAL; 40595590ff0dSUlrich Drepper 40605590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 40615590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 40625590ff0dSUlrich Drepper 40635590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 40645590ff0dSUlrich Drepper } 40655590ff0dSUlrich Drepper 40663480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 40675590ff0dSUlrich Drepper { 40685590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 40695590ff0dSUlrich Drepper } 40705590ff0dSUlrich Drepper 4071db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 40721da177e4SLinus Torvalds { 4073a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 40741da177e4SLinus Torvalds 40751da177e4SLinus Torvalds if (error) 40761da177e4SLinus Torvalds return error; 40771da177e4SLinus Torvalds 4078acfa4380SAl Viro if (!dir->i_op->symlink) 40791da177e4SLinus Torvalds return -EPERM; 40801da177e4SLinus Torvalds 40811da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 40821da177e4SLinus Torvalds if (error) 40831da177e4SLinus Torvalds return error; 40841da177e4SLinus Torvalds 40851da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 4086a74574aaSStephen Smalley if (!error) 4087f38aa942SAmy Griffis fsnotify_create(dir, dentry); 40881da177e4SLinus Torvalds return error; 40891da177e4SLinus Torvalds } 40904d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 40911da177e4SLinus Torvalds 40922e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 40932e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 40941da177e4SLinus Torvalds { 40952ad94ae6SAl Viro int error; 409691a27b2aSJeff Layton struct filename *from; 40976902d925SDave Hansen struct dentry *dentry; 4098dae6ad8fSAl Viro struct path path; 4099f46d3567SJeff Layton unsigned int lookup_flags = 0; 41001da177e4SLinus Torvalds 41011da177e4SLinus Torvalds from = getname(oldname); 41021da177e4SLinus Torvalds if (IS_ERR(from)) 41031da177e4SLinus Torvalds return PTR_ERR(from); 4104f46d3567SJeff Layton retry: 4105f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 41061da177e4SLinus Torvalds error = PTR_ERR(dentry); 41076902d925SDave Hansen if (IS_ERR(dentry)) 4108dae6ad8fSAl Viro goto out_putname; 41096902d925SDave Hansen 411091a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4111a8104a9fSAl Viro if (!error) 411291a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4113921a1650SAl Viro done_path_create(&path, dentry); 4114f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4115f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4116f46d3567SJeff Layton goto retry; 4117f46d3567SJeff Layton } 41186902d925SDave Hansen out_putname: 41191da177e4SLinus Torvalds putname(from); 41201da177e4SLinus Torvalds return error; 41211da177e4SLinus Torvalds } 41221da177e4SLinus Torvalds 41233480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 41245590ff0dSUlrich Drepper { 41255590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 41265590ff0dSUlrich Drepper } 41275590ff0dSUlrich Drepper 4128146a8595SJ. Bruce Fields /** 4129146a8595SJ. Bruce Fields * vfs_link - create a new link 4130146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4131146a8595SJ. Bruce Fields * @dir: new parent 4132146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4133146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4134146a8595SJ. Bruce Fields * 4135146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4136146a8595SJ. Bruce Fields * 4137146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4138146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4139146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4140146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4141146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4142146a8595SJ. Bruce Fields * 4143146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4144146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4145146a8595SJ. Bruce Fields * to be NFS exported. 4146146a8595SJ. Bruce Fields */ 4147146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 41481da177e4SLinus Torvalds { 41491da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 41508de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 41511da177e4SLinus Torvalds int error; 41521da177e4SLinus Torvalds 41531da177e4SLinus Torvalds if (!inode) 41541da177e4SLinus Torvalds return -ENOENT; 41551da177e4SLinus Torvalds 4156a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 41571da177e4SLinus Torvalds if (error) 41581da177e4SLinus Torvalds return error; 41591da177e4SLinus Torvalds 41601da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 41611da177e4SLinus Torvalds return -EXDEV; 41621da177e4SLinus Torvalds 41631da177e4SLinus Torvalds /* 41641da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 41651da177e4SLinus Torvalds */ 41661da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 41671da177e4SLinus Torvalds return -EPERM; 41680bd23d09SEric W. Biederman /* 41690bd23d09SEric W. Biederman * Updating the link count will likely cause i_uid and i_gid to 41700bd23d09SEric W. Biederman * be writen back improperly if their true value is unknown to 41710bd23d09SEric W. Biederman * the vfs. 41720bd23d09SEric W. Biederman */ 41730bd23d09SEric W. Biederman if (HAS_UNMAPPED_ID(inode)) 41740bd23d09SEric W. Biederman return -EPERM; 4175acfa4380SAl Viro if (!dir->i_op->link) 41761da177e4SLinus Torvalds return -EPERM; 41777e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 41781da177e4SLinus Torvalds return -EPERM; 41791da177e4SLinus Torvalds 41801da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 41811da177e4SLinus Torvalds if (error) 41821da177e4SLinus Torvalds return error; 41831da177e4SLinus Torvalds 41845955102cSAl Viro inode_lock(inode); 4185aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4186f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4187aae8a97dSAneesh Kumar K.V error = -ENOENT; 41888de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 41898de52778SAl Viro error = -EMLINK; 4190146a8595SJ. Bruce Fields else { 4191146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4192146a8595SJ. Bruce Fields if (!error) 41931da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4194146a8595SJ. Bruce Fields } 4195f4e0c30cSAl Viro 4196f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4197f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4198f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4199f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4200f4e0c30cSAl Viro } 42015955102cSAl Viro inode_unlock(inode); 4202e31e14ecSStephen Smalley if (!error) 42037e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 42041da177e4SLinus Torvalds return error; 42051da177e4SLinus Torvalds } 42064d359507SAl Viro EXPORT_SYMBOL(vfs_link); 42071da177e4SLinus Torvalds 42081da177e4SLinus Torvalds /* 42091da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 42101da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 42111da177e4SLinus Torvalds * newname. --KAB 42121da177e4SLinus Torvalds * 42131da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 42141da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 42151da177e4SLinus Torvalds * and other special files. --ADM 42161da177e4SLinus Torvalds */ 42172e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 42182e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 42191da177e4SLinus Torvalds { 42201da177e4SLinus Torvalds struct dentry *new_dentry; 4221dae6ad8fSAl Viro struct path old_path, new_path; 4222146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 422311a7b371SAneesh Kumar K.V int how = 0; 42241da177e4SLinus Torvalds int error; 42251da177e4SLinus Torvalds 422611a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4227c04030e1SUlrich Drepper return -EINVAL; 422811a7b371SAneesh Kumar K.V /* 4229f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4230f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4231f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 423211a7b371SAneesh Kumar K.V */ 4233f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4234f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4235f0cc6ffbSLinus Torvalds return -ENOENT; 423611a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4237f0cc6ffbSLinus Torvalds } 4238c04030e1SUlrich Drepper 423911a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 424011a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4241442e31caSJeff Layton retry: 424211a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 42431da177e4SLinus Torvalds if (error) 42442ad94ae6SAl Viro return error; 42452ad94ae6SAl Viro 4246442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4247442e31caSJeff Layton (how & LOOKUP_REVAL)); 42481da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 42496902d925SDave Hansen if (IS_ERR(new_dentry)) 4250dae6ad8fSAl Viro goto out; 4251dae6ad8fSAl Viro 4252dae6ad8fSAl Viro error = -EXDEV; 4253dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4254dae6ad8fSAl Viro goto out_dput; 4255800179c9SKees Cook error = may_linkat(&old_path); 4256800179c9SKees Cook if (unlikely(error)) 4257800179c9SKees Cook goto out_dput; 4258dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4259be6d3e56SKentaro Takeda if (error) 4260a8104a9fSAl Viro goto out_dput; 4261146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 426275c3f29dSDave Hansen out_dput: 4263921a1650SAl Viro done_path_create(&new_path, new_dentry); 4264146a8595SJ. Bruce Fields if (delegated_inode) { 4265146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4266d22e6338SOleg Drokin if (!error) { 4267d22e6338SOleg Drokin path_put(&old_path); 4268146a8595SJ. Bruce Fields goto retry; 4269146a8595SJ. Bruce Fields } 4270d22e6338SOleg Drokin } 4271442e31caSJeff Layton if (retry_estale(error, how)) { 4272d22e6338SOleg Drokin path_put(&old_path); 4273442e31caSJeff Layton how |= LOOKUP_REVAL; 4274442e31caSJeff Layton goto retry; 4275442e31caSJeff Layton } 42761da177e4SLinus Torvalds out: 42772d8f3038SAl Viro path_put(&old_path); 42781da177e4SLinus Torvalds 42791da177e4SLinus Torvalds return error; 42801da177e4SLinus Torvalds } 42811da177e4SLinus Torvalds 42823480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 42835590ff0dSUlrich Drepper { 4284c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 42855590ff0dSUlrich Drepper } 42865590ff0dSUlrich Drepper 4287bc27027aSMiklos Szeredi /** 4288bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4289bc27027aSMiklos Szeredi * @old_dir: parent of source 4290bc27027aSMiklos Szeredi * @old_dentry: source 4291bc27027aSMiklos Szeredi * @new_dir: parent of destination 4292bc27027aSMiklos Szeredi * @new_dentry: destination 4293bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4294520c8b16SMiklos Szeredi * @flags: rename flags 4295bc27027aSMiklos Szeredi * 4296bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4297bc27027aSMiklos Szeredi * 4298bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4299bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4300bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4301bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4302bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4303bc27027aSMiklos Szeredi * so. 4304bc27027aSMiklos Szeredi * 4305bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4306bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4307bc27027aSMiklos Szeredi * to be NFS exported. 4308bc27027aSMiklos Szeredi * 43091da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 43101da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 43111da177e4SLinus Torvalds * Problems: 4312d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 43131da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 43141da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4315a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 43161da177e4SLinus Torvalds * story. 43176cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 43186cedba89SJ. Bruce Fields * and source (if it is not a directory). 43191b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 43201da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 43211da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4322a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 43231da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 43241da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 43251da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4326a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 43271da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 43281da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 43291da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4330e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 43311b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 43321da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4333c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 43341da177e4SLinus Torvalds * locking]. 43351da177e4SLinus Torvalds */ 43361da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 43378e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4338520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 43391da177e4SLinus Torvalds { 43401da177e4SLinus Torvalds int error; 4341bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 434259b0df21SEric Paris const unsigned char *old_name; 4343bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4344bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4345da1ce067SMiklos Szeredi bool new_is_dir = false; 4346da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 43471da177e4SLinus Torvalds 43489409e22aSMiklos Szeredi /* 43499409e22aSMiklos Szeredi * Check source == target. 43509409e22aSMiklos Szeredi * On overlayfs need to look at underlying inodes. 43519409e22aSMiklos Szeredi */ 43522d902671SMiklos Szeredi if (d_real_inode(old_dentry) == d_real_inode(new_dentry)) 43531da177e4SLinus Torvalds return 0; 43541da177e4SLinus Torvalds 43551da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 43561da177e4SLinus Torvalds if (error) 43571da177e4SLinus Torvalds return error; 43581da177e4SLinus Torvalds 4359da1ce067SMiklos Szeredi if (!target) { 4360a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4361da1ce067SMiklos Szeredi } else { 4362da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4363da1ce067SMiklos Szeredi 4364da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43651da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4366da1ce067SMiklos Szeredi else 4367da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4368da1ce067SMiklos Szeredi } 43691da177e4SLinus Torvalds if (error) 43701da177e4SLinus Torvalds return error; 43711da177e4SLinus Torvalds 43722773bf00SMiklos Szeredi if (!old_dir->i_op->rename) 43731da177e4SLinus Torvalds return -EPERM; 43741da177e4SLinus Torvalds 4375bc27027aSMiklos Szeredi /* 4376bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4377bc27027aSMiklos Szeredi * we'll need to flip '..'. 4378bc27027aSMiklos Szeredi */ 4379da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4380da1ce067SMiklos Szeredi if (is_dir) { 4381bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4382bc27027aSMiklos Szeredi if (error) 4383bc27027aSMiklos Szeredi return error; 4384bc27027aSMiklos Szeredi } 4385da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4386da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4387da1ce067SMiklos Szeredi if (error) 4388da1ce067SMiklos Szeredi return error; 4389da1ce067SMiklos Szeredi } 4390da1ce067SMiklos Szeredi } 43910eeca283SRobert Love 43920b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 43930b3974ebSMiklos Szeredi flags); 4394bc27027aSMiklos Szeredi if (error) 4395bc27027aSMiklos Szeredi return error; 4396bc27027aSMiklos Szeredi 4397bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4398bc27027aSMiklos Szeredi dget(new_dentry); 4399da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4400bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4401bc27027aSMiklos Szeredi else if (target) 44025955102cSAl Viro inode_lock(target); 4403bc27027aSMiklos Szeredi 4404bc27027aSMiklos Szeredi error = -EBUSY; 44057af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4406bc27027aSMiklos Szeredi goto out; 4407bc27027aSMiklos Szeredi 4408da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4409bc27027aSMiklos Szeredi error = -EMLINK; 4410da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4411bc27027aSMiklos Szeredi goto out; 4412da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4413da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4414da1ce067SMiklos Szeredi goto out; 4415da1ce067SMiklos Szeredi } 4416da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4417bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4418da1ce067SMiklos Szeredi if (!is_dir) { 4419bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4420bc27027aSMiklos Szeredi if (error) 4421bc27027aSMiklos Szeredi goto out; 4422da1ce067SMiklos Szeredi } 4423da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4424bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4425bc27027aSMiklos Szeredi if (error) 4426bc27027aSMiklos Szeredi goto out; 4427bc27027aSMiklos Szeredi } 44282773bf00SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4429520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4430bc27027aSMiklos Szeredi if (error) 4431bc27027aSMiklos Szeredi goto out; 4432bc27027aSMiklos Szeredi 4433da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 44341da177e4SLinus Torvalds if (is_dir) 4435bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4436bc27027aSMiklos Szeredi dont_mount(new_dentry); 44378ed936b5SEric W. Biederman detach_mounts(new_dentry); 4438bc27027aSMiklos Szeredi } 4439da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4440da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4441bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4442da1ce067SMiklos Szeredi else 4443da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4444da1ce067SMiklos Szeredi } 4445bc27027aSMiklos Szeredi out: 4446da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4447bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4448bc27027aSMiklos Szeredi else if (target) 44495955102cSAl Viro inode_unlock(target); 4450bc27027aSMiklos Szeredi dput(new_dentry); 4451da1ce067SMiklos Szeredi if (!error) { 4452123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4453da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4454da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4455da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4456da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4457da1ce067SMiklos Szeredi } 4458da1ce067SMiklos Szeredi } 44590eeca283SRobert Love fsnotify_oldname_free(old_name); 44600eeca283SRobert Love 44611da177e4SLinus Torvalds return error; 44621da177e4SLinus Torvalds } 44634d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 44641da177e4SLinus Torvalds 4465520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4466520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 44671da177e4SLinus Torvalds { 44681da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 44691da177e4SLinus Torvalds struct dentry *trap; 4470f5beed75SAl Viro struct path old_path, new_path; 4471f5beed75SAl Viro struct qstr old_last, new_last; 4472f5beed75SAl Viro int old_type, new_type; 44738e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 447491a27b2aSJeff Layton struct filename *from; 447591a27b2aSJeff Layton struct filename *to; 4476f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4477c6a94284SJeff Layton bool should_retry = false; 44782ad94ae6SAl Viro int error; 4479520c8b16SMiklos Szeredi 44800d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4481da1ce067SMiklos Szeredi return -EINVAL; 4482da1ce067SMiklos Szeredi 44830d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 44840d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4485520c8b16SMiklos Szeredi return -EINVAL; 4486520c8b16SMiklos Szeredi 44870d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 44880d7a8555SMiklos Szeredi return -EPERM; 44890d7a8555SMiklos Szeredi 4490f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4491f5beed75SAl Viro target_flags = 0; 4492f5beed75SAl Viro 4493c6a94284SJeff Layton retry: 4494f5beed75SAl Viro from = user_path_parent(olddfd, oldname, 4495f5beed75SAl Viro &old_path, &old_last, &old_type, lookup_flags); 449691a27b2aSJeff Layton if (IS_ERR(from)) { 449791a27b2aSJeff Layton error = PTR_ERR(from); 44981da177e4SLinus Torvalds goto exit; 449991a27b2aSJeff Layton } 45001da177e4SLinus Torvalds 4501f5beed75SAl Viro to = user_path_parent(newdfd, newname, 4502f5beed75SAl Viro &new_path, &new_last, &new_type, lookup_flags); 450391a27b2aSJeff Layton if (IS_ERR(to)) { 450491a27b2aSJeff Layton error = PTR_ERR(to); 45051da177e4SLinus Torvalds goto exit1; 450691a27b2aSJeff Layton } 45071da177e4SLinus Torvalds 45081da177e4SLinus Torvalds error = -EXDEV; 4509f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 45101da177e4SLinus Torvalds goto exit2; 45111da177e4SLinus Torvalds 45121da177e4SLinus Torvalds error = -EBUSY; 4513f5beed75SAl Viro if (old_type != LAST_NORM) 45141da177e4SLinus Torvalds goto exit2; 45151da177e4SLinus Torvalds 45160a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 45170a7c3937SMiklos Szeredi error = -EEXIST; 4518f5beed75SAl Viro if (new_type != LAST_NORM) 45191da177e4SLinus Torvalds goto exit2; 45201da177e4SLinus Torvalds 4521f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4522c30dabfeSJan Kara if (error) 4523c30dabfeSJan Kara goto exit2; 4524c30dabfeSJan Kara 45258e6d782cSJ. Bruce Fields retry_deleg: 4526f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 45271da177e4SLinus Torvalds 4528f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 45291da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 45301da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 45311da177e4SLinus Torvalds goto exit3; 45321da177e4SLinus Torvalds /* source must exist */ 45331da177e4SLinus Torvalds error = -ENOENT; 4534b18825a7SDavid Howells if (d_is_negative(old_dentry)) 45351da177e4SLinus Torvalds goto exit4; 4536f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 45371da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 45381da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 45391da177e4SLinus Torvalds goto exit4; 45400a7c3937SMiklos Szeredi error = -EEXIST; 45410a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 45420a7c3937SMiklos Szeredi goto exit5; 4543da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4544da1ce067SMiklos Szeredi error = -ENOENT; 4545da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4546da1ce067SMiklos Szeredi goto exit5; 4547da1ce067SMiklos Szeredi 4548da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4549da1ce067SMiklos Szeredi error = -ENOTDIR; 4550f5beed75SAl Viro if (new_last.name[new_last.len]) 4551da1ce067SMiklos Szeredi goto exit5; 4552da1ce067SMiklos Szeredi } 4553da1ce067SMiklos Szeredi } 45540a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 45550a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 45560a7c3937SMiklos Szeredi error = -ENOTDIR; 4557f5beed75SAl Viro if (old_last.name[old_last.len]) 45580a7c3937SMiklos Szeredi goto exit5; 4559f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 45600a7c3937SMiklos Szeredi goto exit5; 45610a7c3937SMiklos Szeredi } 45620a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 45630a7c3937SMiklos Szeredi error = -EINVAL; 45640a7c3937SMiklos Szeredi if (old_dentry == trap) 45650a7c3937SMiklos Szeredi goto exit5; 45661da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4567da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 45681da177e4SLinus Torvalds error = -ENOTEMPTY; 45691da177e4SLinus Torvalds if (new_dentry == trap) 45701da177e4SLinus Torvalds goto exit5; 45711da177e4SLinus Torvalds 4572f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4573f5beed75SAl Viro &new_path, new_dentry, flags); 4574be6d3e56SKentaro Takeda if (error) 4575c30dabfeSJan Kara goto exit5; 4576f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4577f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4578520c8b16SMiklos Szeredi &delegated_inode, flags); 45791da177e4SLinus Torvalds exit5: 45801da177e4SLinus Torvalds dput(new_dentry); 45811da177e4SLinus Torvalds exit4: 45821da177e4SLinus Torvalds dput(old_dentry); 45831da177e4SLinus Torvalds exit3: 4584f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 45858e6d782cSJ. Bruce Fields if (delegated_inode) { 45868e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 45878e6d782cSJ. Bruce Fields if (!error) 45888e6d782cSJ. Bruce Fields goto retry_deleg; 45898e6d782cSJ. Bruce Fields } 4590f5beed75SAl Viro mnt_drop_write(old_path.mnt); 45911da177e4SLinus Torvalds exit2: 4592c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4593c6a94284SJeff Layton should_retry = true; 4594f5beed75SAl Viro path_put(&new_path); 45952ad94ae6SAl Viro putname(to); 45961da177e4SLinus Torvalds exit1: 4597f5beed75SAl Viro path_put(&old_path); 45981da177e4SLinus Torvalds putname(from); 4599c6a94284SJeff Layton if (should_retry) { 4600c6a94284SJeff Layton should_retry = false; 4601c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4602c6a94284SJeff Layton goto retry; 4603c6a94284SJeff Layton } 46042ad94ae6SAl Viro exit: 46051da177e4SLinus Torvalds return error; 46061da177e4SLinus Torvalds } 46071da177e4SLinus Torvalds 4608520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4609520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4610520c8b16SMiklos Szeredi { 4611520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4612520c8b16SMiklos Szeredi } 4613520c8b16SMiklos Szeredi 4614a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 46155590ff0dSUlrich Drepper { 4616520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 46175590ff0dSUlrich Drepper } 46185590ff0dSUlrich Drepper 4619787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4620787fb6bcSMiklos Szeredi { 4621787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4622787fb6bcSMiklos Szeredi if (error) 4623787fb6bcSMiklos Szeredi return error; 4624787fb6bcSMiklos Szeredi 4625787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4626787fb6bcSMiklos Szeredi return -EPERM; 4627787fb6bcSMiklos Szeredi 4628787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4629787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4630787fb6bcSMiklos Szeredi } 4631787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4632787fb6bcSMiklos Szeredi 46335d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 46341da177e4SLinus Torvalds { 46355d826c84SAl Viro int len = PTR_ERR(link); 46361da177e4SLinus Torvalds if (IS_ERR(link)) 46371da177e4SLinus Torvalds goto out; 46381da177e4SLinus Torvalds 46391da177e4SLinus Torvalds len = strlen(link); 46401da177e4SLinus Torvalds if (len > (unsigned) buflen) 46411da177e4SLinus Torvalds len = buflen; 46421da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 46431da177e4SLinus Torvalds len = -EFAULT; 46441da177e4SLinus Torvalds out: 46451da177e4SLinus Torvalds return len; 46461da177e4SLinus Torvalds } 46471da177e4SLinus Torvalds 46481da177e4SLinus Torvalds /* 46491da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 46506b255391SAl Viro * have ->get_link() not calling nd_jump_link(). Using (or not using) it 46516b255391SAl Viro * for any given inode is up to filesystem. 46521da177e4SLinus Torvalds */ 46531da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 46541da177e4SLinus Torvalds { 4655fceef393SAl Viro DEFINE_DELAYED_CALL(done); 46565f2c4179SAl Viro struct inode *inode = d_inode(dentry); 46575f2c4179SAl Viro const char *link = inode->i_link; 4658694a1764SMarcin Slusarz int res; 4659cc314eefSLinus Torvalds 4660d4dee48bSAl Viro if (!link) { 4661fceef393SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4662680baacbSAl Viro if (IS_ERR(link)) 4663680baacbSAl Viro return PTR_ERR(link); 4664d4dee48bSAl Viro } 4665680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 4666fceef393SAl Viro do_delayed_call(&done); 4667694a1764SMarcin Slusarz return res; 46681da177e4SLinus Torvalds } 46694d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 46701da177e4SLinus Torvalds 46711da177e4SLinus Torvalds /* get the link contents into pagecache */ 46726b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4673fceef393SAl Viro struct delayed_call *callback) 46741da177e4SLinus Torvalds { 4675ebd09abbSDuane Griffin char *kaddr; 46761da177e4SLinus Torvalds struct page *page; 46776b255391SAl Viro struct address_space *mapping = inode->i_mapping; 46786b255391SAl Viro 4679d3883d4fSAl Viro if (!dentry) { 4680d3883d4fSAl Viro page = find_get_page(mapping, 0); 4681d3883d4fSAl Viro if (!page) 46826b255391SAl Viro return ERR_PTR(-ECHILD); 4683d3883d4fSAl Viro if (!PageUptodate(page)) { 4684d3883d4fSAl Viro put_page(page); 4685d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4686d3883d4fSAl Viro } 4687d3883d4fSAl Viro } else { 4688090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 46891da177e4SLinus Torvalds if (IS_ERR(page)) 46906fe6900eSNick Piggin return (char*)page; 4691d3883d4fSAl Viro } 4692fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 469321fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 469421fc61c7SAl Viro kaddr = page_address(page); 46956b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4696ebd09abbSDuane Griffin return kaddr; 46971da177e4SLinus Torvalds } 46981da177e4SLinus Torvalds 46996b255391SAl Viro EXPORT_SYMBOL(page_get_link); 47001da177e4SLinus Torvalds 4701fceef393SAl Viro void page_put_link(void *arg) 47021da177e4SLinus Torvalds { 4703fceef393SAl Viro put_page(arg); 47041da177e4SLinus Torvalds } 47054d359507SAl Viro EXPORT_SYMBOL(page_put_link); 47061da177e4SLinus Torvalds 4707aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4708aa80deabSAl Viro { 4709fceef393SAl Viro DEFINE_DELAYED_CALL(done); 47106b255391SAl Viro int res = readlink_copy(buffer, buflen, 47116b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4712fceef393SAl Viro &done)); 4713fceef393SAl Viro do_delayed_call(&done); 4714aa80deabSAl Viro return res; 4715aa80deabSAl Viro } 4716aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4717aa80deabSAl Viro 471854566b2cSNick Piggin /* 471954566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 472054566b2cSNick Piggin */ 472154566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 47221da177e4SLinus Torvalds { 47231da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 47240adb25d2SKirill Korotaev struct page *page; 4725afddba49SNick Piggin void *fsdata; 4726beb497abSDmitriy Monakhov int err; 472754566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 472854566b2cSNick Piggin if (nofs) 472954566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 47301da177e4SLinus Torvalds 47317e53cac4SNeilBrown retry: 4732afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 473354566b2cSNick Piggin flags, &page, &fsdata); 47341da177e4SLinus Torvalds if (err) 4735afddba49SNick Piggin goto fail; 4736afddba49SNick Piggin 473721fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4738afddba49SNick Piggin 4739afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4740afddba49SNick Piggin page, fsdata); 47411da177e4SLinus Torvalds if (err < 0) 47421da177e4SLinus Torvalds goto fail; 4743afddba49SNick Piggin if (err < len-1) 4744afddba49SNick Piggin goto retry; 4745afddba49SNick Piggin 47461da177e4SLinus Torvalds mark_inode_dirty(inode); 47471da177e4SLinus Torvalds return 0; 47481da177e4SLinus Torvalds fail: 47491da177e4SLinus Torvalds return err; 47501da177e4SLinus Torvalds } 47514d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 47521da177e4SLinus Torvalds 47530adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 47540adb25d2SKirill Korotaev { 47550adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4756c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 47570adb25d2SKirill Korotaev } 47584d359507SAl Viro EXPORT_SYMBOL(page_symlink); 47590adb25d2SKirill Korotaev 476092e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 47611da177e4SLinus Torvalds .readlink = generic_readlink, 47626b255391SAl Viro .get_link = page_get_link, 47631da177e4SLinus Torvalds }; 47641da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4765