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> 381da177e4SLinus Torvalds #include <asm/uaccess.h> 391da177e4SLinus Torvalds 40e81e3f4dSEric Paris #include "internal.h" 41c7105365SAl Viro #include "mount.h" 42e81e3f4dSEric Paris 431da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 441da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 451da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 461da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 471da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 481da177e4SLinus Torvalds * 491da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 501da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 511da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 521da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 531da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 541da177e4SLinus Torvalds * the special cases of the former code. 551da177e4SLinus Torvalds * 561da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 571da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 581da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 591da177e4SLinus Torvalds * 601da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 611da177e4SLinus Torvalds * resolution to correspond with current state of the code. 621da177e4SLinus Torvalds * 631da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 641da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 651da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 661da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 671da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 681da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 691da177e4SLinus Torvalds */ 701da177e4SLinus Torvalds 711da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 721da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 731da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 741da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 751da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 761da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7725985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 781da177e4SLinus Torvalds * 791da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 801da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 811da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 821da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 831da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 841da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 851da177e4SLinus Torvalds * and in the old Linux semantics. 861da177e4SLinus Torvalds */ 871da177e4SLinus Torvalds 881da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 891da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 901da177e4SLinus Torvalds * 911da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 921da177e4SLinus Torvalds */ 931da177e4SLinus Torvalds 941da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 951da177e4SLinus Torvalds * inside the path - always follow. 961da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 971da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 981da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 991da177e4SLinus Torvalds * otherwise - don't follow. 1001da177e4SLinus Torvalds * (applied in that order). 1011da177e4SLinus Torvalds * 1021da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1031da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1041da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1051da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1061da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1071da177e4SLinus Torvalds */ 1081da177e4SLinus Torvalds /* 1091da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 110a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1111da177e4SLinus Torvalds * any extra contention... 1121da177e4SLinus Torvalds */ 1131da177e4SLinus Torvalds 1141da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1151da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1161da177e4SLinus Torvalds * kernel data space before using them.. 1171da177e4SLinus Torvalds * 1181da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1191da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1201da177e4SLinus Torvalds */ 1217950e385SJeff Layton 122fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12391a27b2aSJeff Layton 12451f39a1fSDavid Drysdale struct filename * 12591a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12691a27b2aSJeff Layton { 12794b5d262SAl Viro struct filename *result; 1287950e385SJeff Layton char *kname; 12994b5d262SAl Viro int len; 1301da177e4SLinus Torvalds 1317ac86265SJeff Layton result = audit_reusename(filename); 1327ac86265SJeff Layton if (result) 1337ac86265SJeff Layton return result; 1347ac86265SJeff Layton 1357950e385SJeff Layton result = __getname(); 1363f9f0aa6SLinus Torvalds if (unlikely(!result)) 1374043cde8SEric Paris return ERR_PTR(-ENOMEM); 1381da177e4SLinus Torvalds 1397950e385SJeff Layton /* 1407950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1417950e385SJeff Layton * allocation 1427950e385SJeff Layton */ 143fd2f7cb5SAl Viro kname = (char *)result->iname; 14491a27b2aSJeff Layton result->name = kname; 1457950e385SJeff Layton 14694b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 14791a27b2aSJeff Layton if (unlikely(len < 0)) { 14894b5d262SAl Viro __putname(result); 14994b5d262SAl Viro return ERR_PTR(len); 15091a27b2aSJeff Layton } 1513f9f0aa6SLinus Torvalds 1527950e385SJeff Layton /* 1537950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1547950e385SJeff Layton * separate struct filename so we can dedicate the entire 1557950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1567950e385SJeff Layton * userland. 1577950e385SJeff Layton */ 15894b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 159fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1607950e385SJeff Layton kname = (char *)result; 1617950e385SJeff Layton 162fd2f7cb5SAl Viro /* 163fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 164fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 165fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 166fd2f7cb5SAl Viro */ 167fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 16894b5d262SAl Viro if (unlikely(!result)) { 16994b5d262SAl Viro __putname(kname); 17094b5d262SAl Viro return ERR_PTR(-ENOMEM); 1717950e385SJeff Layton } 1727950e385SJeff Layton result->name = kname; 17394b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17494b5d262SAl Viro if (unlikely(len < 0)) { 17594b5d262SAl Viro __putname(kname); 17694b5d262SAl Viro kfree(result); 17794b5d262SAl Viro return ERR_PTR(len); 17894b5d262SAl Viro } 17994b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18094b5d262SAl Viro __putname(kname); 18194b5d262SAl Viro kfree(result); 18294b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18394b5d262SAl Viro } 1847950e385SJeff Layton } 1857950e385SJeff Layton 18694b5d262SAl Viro result->refcnt = 1; 1873f9f0aa6SLinus Torvalds /* The empty path is special. */ 1883f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1893f9f0aa6SLinus Torvalds if (empty) 1901fa1e7f6SAndy Whitcroft *empty = 1; 19194b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19294b5d262SAl Viro putname(result); 19394b5d262SAl Viro return ERR_PTR(-ENOENT); 1941da177e4SLinus Torvalds } 19594b5d262SAl Viro } 1967950e385SJeff Layton 1977950e385SJeff Layton result->uptr = filename; 198c4ad8f98SLinus Torvalds result->aname = NULL; 1991da177e4SLinus Torvalds audit_getname(result); 2001da177e4SLinus Torvalds return result; 2013f9f0aa6SLinus Torvalds } 2023f9f0aa6SLinus Torvalds 20391a27b2aSJeff Layton struct filename * 20491a27b2aSJeff Layton getname(const char __user * filename) 205f52e0c11SAl Viro { 206f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 207f52e0c11SAl Viro } 208f52e0c11SAl Viro 209c4ad8f98SLinus Torvalds struct filename * 210c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 211c4ad8f98SLinus Torvalds { 212c4ad8f98SLinus Torvalds struct filename *result; 21308518549SPaul Moore int len = strlen(filename) + 1; 214c4ad8f98SLinus Torvalds 215c4ad8f98SLinus Torvalds result = __getname(); 216c4ad8f98SLinus Torvalds if (unlikely(!result)) 217c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 218c4ad8f98SLinus Torvalds 21908518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 220fd2f7cb5SAl Viro result->name = (char *)result->iname; 22108518549SPaul Moore } else if (len <= PATH_MAX) { 22208518549SPaul Moore struct filename *tmp; 22308518549SPaul Moore 22408518549SPaul Moore tmp = kmalloc(sizeof(*tmp), GFP_KERNEL); 22508518549SPaul Moore if (unlikely(!tmp)) { 22608518549SPaul Moore __putname(result); 22708518549SPaul Moore return ERR_PTR(-ENOMEM); 22808518549SPaul Moore } 22908518549SPaul Moore tmp->name = (char *)result; 23008518549SPaul Moore result = tmp; 23108518549SPaul Moore } else { 23208518549SPaul Moore __putname(result); 23308518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23408518549SPaul Moore } 23508518549SPaul Moore memcpy((char *)result->name, filename, len); 236c4ad8f98SLinus Torvalds result->uptr = NULL; 237c4ad8f98SLinus Torvalds result->aname = NULL; 23855422d0bSPaul Moore result->refcnt = 1; 239fd3522fdSPaul Moore audit_getname(result); 240c4ad8f98SLinus Torvalds 241c4ad8f98SLinus Torvalds return result; 242c4ad8f98SLinus Torvalds } 243c4ad8f98SLinus Torvalds 24491a27b2aSJeff Layton void putname(struct filename *name) 2451da177e4SLinus Torvalds { 24655422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 24755422d0bSPaul Moore 24855422d0bSPaul Moore if (--name->refcnt > 0) 24955422d0bSPaul Moore return; 25055422d0bSPaul Moore 251fd2f7cb5SAl Viro if (name->name != name->iname) { 25255422d0bSPaul Moore __putname(name->name); 25355422d0bSPaul Moore kfree(name); 25455422d0bSPaul Moore } else 25555422d0bSPaul Moore __putname(name); 2561da177e4SLinus Torvalds } 2571da177e4SLinus Torvalds 258e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 259e77819e5SLinus Torvalds { 26084635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 261e77819e5SLinus Torvalds struct posix_acl *acl; 262e77819e5SLinus Torvalds 263e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2643567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2653567866bSAl Viro if (!acl) 266e77819e5SLinus Torvalds return -EAGAIN; 2673567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 2683567866bSAl Viro if (acl == ACL_NOT_CACHED) 269e77819e5SLinus Torvalds return -ECHILD; 270206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 271e77819e5SLinus Torvalds } 272e77819e5SLinus Torvalds 2732982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2744e34e719SChristoph Hellwig if (IS_ERR(acl)) 2754e34e719SChristoph Hellwig return PTR_ERR(acl); 276e77819e5SLinus Torvalds if (acl) { 277e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 278e77819e5SLinus Torvalds posix_acl_release(acl); 279e77819e5SLinus Torvalds return error; 280e77819e5SLinus Torvalds } 28184635d68SLinus Torvalds #endif 282e77819e5SLinus Torvalds 283e77819e5SLinus Torvalds return -EAGAIN; 284e77819e5SLinus Torvalds } 285e77819e5SLinus Torvalds 2865909ccaaSLinus Torvalds /* 287948409c7SAndreas Gruenbacher * This does the basic permission checking 2885909ccaaSLinus Torvalds */ 2897e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2905909ccaaSLinus Torvalds { 29126cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2925909ccaaSLinus Torvalds 2938e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2945909ccaaSLinus Torvalds mode >>= 6; 2955909ccaaSLinus Torvalds else { 296e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2977e40145eSAl Viro int error = check_acl(inode, mask); 2985909ccaaSLinus Torvalds if (error != -EAGAIN) 2995909ccaaSLinus Torvalds return error; 3005909ccaaSLinus Torvalds } 3015909ccaaSLinus Torvalds 3025909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3035909ccaaSLinus Torvalds mode >>= 3; 3045909ccaaSLinus Torvalds } 3055909ccaaSLinus Torvalds 3065909ccaaSLinus Torvalds /* 3075909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3085909ccaaSLinus Torvalds */ 3099c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3105909ccaaSLinus Torvalds return 0; 3115909ccaaSLinus Torvalds return -EACCES; 3125909ccaaSLinus Torvalds } 3131da177e4SLinus Torvalds 3141da177e4SLinus Torvalds /** 3151da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3161da177e4SLinus Torvalds * @inode: inode to check access rights for 3178fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3181da177e4SLinus Torvalds * 3191da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3201da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3211da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 322b74c79e9SNick Piggin * are used for other things. 323b74c79e9SNick Piggin * 324b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 325b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 326b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3271da177e4SLinus Torvalds */ 3282830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3291da177e4SLinus Torvalds { 3305909ccaaSLinus Torvalds int ret; 3311da177e4SLinus Torvalds 3321da177e4SLinus Torvalds /* 333948409c7SAndreas Gruenbacher * Do the basic permission checks. 3341da177e4SLinus Torvalds */ 3357e40145eSAl Viro ret = acl_permission_check(inode, mask); 3365909ccaaSLinus Torvalds if (ret != -EACCES) 3375909ccaaSLinus Torvalds return ret; 3381da177e4SLinus Torvalds 339d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 340d594e7ecSAl Viro /* DACs are overridable for directories */ 34123adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 342d594e7ecSAl Viro return 0; 343d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34423adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34523adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 346d594e7ecSAl Viro return 0; 347d594e7ecSAl Viro return -EACCES; 348d594e7ecSAl Viro } 3491da177e4SLinus Torvalds /* 3501da177e4SLinus Torvalds * Read/write DACs are always overridable. 351d594e7ecSAl Viro * Executable DACs are overridable when there is 352d594e7ecSAl Viro * at least one exec bit set. 3531da177e4SLinus Torvalds */ 354d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 35523adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3561da177e4SLinus Torvalds return 0; 3571da177e4SLinus Torvalds 3581da177e4SLinus Torvalds /* 3591da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3601da177e4SLinus Torvalds */ 3617ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 362d594e7ecSAl Viro if (mask == MAY_READ) 36323adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3641da177e4SLinus Torvalds return 0; 3651da177e4SLinus Torvalds 3661da177e4SLinus Torvalds return -EACCES; 3671da177e4SLinus Torvalds } 3684d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3691da177e4SLinus Torvalds 3703ddcd056SLinus Torvalds /* 3713ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3723ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3733ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3743ddcd056SLinus Torvalds * permission function, use the fast case". 3753ddcd056SLinus Torvalds */ 3763ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3773ddcd056SLinus Torvalds { 3783ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3793ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3803ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3813ddcd056SLinus Torvalds 3823ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3833ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3843ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3853ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3863ddcd056SLinus Torvalds } 3873ddcd056SLinus Torvalds return generic_permission(inode, mask); 3883ddcd056SLinus Torvalds } 3893ddcd056SLinus Torvalds 390cb23beb5SChristoph Hellwig /** 3910bdaea90SDavid Howells * __inode_permission - Check for access rights to a given inode 3920bdaea90SDavid Howells * @inode: Inode to check permission on 3930bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 394cb23beb5SChristoph Hellwig * 3950bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. 396948409c7SAndreas Gruenbacher * 397948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 3980bdaea90SDavid Howells * 3990bdaea90SDavid Howells * This does not check for a read-only file system. You probably want 4000bdaea90SDavid Howells * inode_permission(). 401cb23beb5SChristoph Hellwig */ 4020bdaea90SDavid Howells int __inode_permission(struct inode *inode, int mask) 4031da177e4SLinus Torvalds { 404e6305c43SAl Viro int retval; 4051da177e4SLinus Torvalds 4063ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 4071da177e4SLinus Torvalds /* 4081da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 4091da177e4SLinus Torvalds */ 4101da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 4111da177e4SLinus Torvalds return -EACCES; 4121da177e4SLinus Torvalds } 4131da177e4SLinus Torvalds 4143ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 4151da177e4SLinus Torvalds if (retval) 4161da177e4SLinus Torvalds return retval; 4171da177e4SLinus Torvalds 41808ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 41908ce5f16SSerge E. Hallyn if (retval) 42008ce5f16SSerge E. Hallyn return retval; 42108ce5f16SSerge E. Hallyn 422d09ca739SEric Paris return security_inode_permission(inode, mask); 4231da177e4SLinus Torvalds } 424bd5d0856SMiklos Szeredi EXPORT_SYMBOL(__inode_permission); 4251da177e4SLinus Torvalds 426f4d6ff89SAl Viro /** 4270bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 4280bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 42955852635SRandy Dunlap * @inode: Inode to check permission on 4300bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4310bdaea90SDavid Howells * 4320bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4330bdaea90SDavid Howells */ 4340bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4350bdaea90SDavid Howells { 4360bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4370bdaea90SDavid Howells umode_t mode = inode->i_mode; 4380bdaea90SDavid Howells 4390bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 4400bdaea90SDavid Howells if ((sb->s_flags & MS_RDONLY) && 4410bdaea90SDavid Howells (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4420bdaea90SDavid Howells return -EROFS; 4430bdaea90SDavid Howells } 4440bdaea90SDavid Howells return 0; 4450bdaea90SDavid Howells } 4460bdaea90SDavid Howells 4470bdaea90SDavid Howells /** 4480bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4490bdaea90SDavid Howells * @inode: Inode to check permission on 4500bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4510bdaea90SDavid Howells * 4520bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4530bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4540bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4550bdaea90SDavid Howells * 4560bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4570bdaea90SDavid Howells */ 4580bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4590bdaea90SDavid Howells { 4600bdaea90SDavid Howells int retval; 4610bdaea90SDavid Howells 4620bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4630bdaea90SDavid Howells if (retval) 4640bdaea90SDavid Howells return retval; 4650bdaea90SDavid Howells return __inode_permission(inode, mask); 4660bdaea90SDavid Howells } 4674d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4680bdaea90SDavid Howells 4690bdaea90SDavid Howells /** 4705dd784d0SJan Blunck * path_get - get a reference to a path 4715dd784d0SJan Blunck * @path: path to get the reference to 4725dd784d0SJan Blunck * 4735dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4745dd784d0SJan Blunck */ 475dcf787f3SAl Viro void path_get(const struct path *path) 4765dd784d0SJan Blunck { 4775dd784d0SJan Blunck mntget(path->mnt); 4785dd784d0SJan Blunck dget(path->dentry); 4795dd784d0SJan Blunck } 4805dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4815dd784d0SJan Blunck 4825dd784d0SJan Blunck /** 4831d957f9bSJan Blunck * path_put - put a reference to a path 4841d957f9bSJan Blunck * @path: path to put the reference to 4851d957f9bSJan Blunck * 4861d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4871d957f9bSJan Blunck */ 488dcf787f3SAl Viro void path_put(const struct path *path) 4891da177e4SLinus Torvalds { 4901d957f9bSJan Blunck dput(path->dentry); 4911d957f9bSJan Blunck mntput(path->mnt); 4921da177e4SLinus Torvalds } 4931d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4941da177e4SLinus Torvalds 495894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 4961f55a6ecSAl Viro struct nameidata { 4971f55a6ecSAl Viro struct path path; 4981f55a6ecSAl Viro struct qstr last; 4991f55a6ecSAl Viro struct path root; 5001f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 5011f55a6ecSAl Viro unsigned int flags; 5021f55a6ecSAl Viro unsigned seq, m_seq; 5031f55a6ecSAl Viro int last_type; 5041f55a6ecSAl Viro unsigned depth; 505756daf26SNeilBrown int total_link_count; 506697fc6caSAl Viro struct saved { 507697fc6caSAl Viro struct path link; 508697fc6caSAl Viro void *cookie; 509697fc6caSAl Viro const char *name; 510894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5111f55a6ecSAl Viro }; 5121f55a6ecSAl Viro 513756daf26SNeilBrown static struct nameidata *set_nameidata(struct nameidata *p) 514894bc8c4SAl Viro { 515756daf26SNeilBrown struct nameidata *old = current->nameidata; 516756daf26SNeilBrown p->stack = p->internal; 517756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 518756daf26SNeilBrown current->nameidata = p; 519756daf26SNeilBrown return old; 520894bc8c4SAl Viro } 521894bc8c4SAl Viro 522756daf26SNeilBrown static void restore_nameidata(struct nameidata *old) 523894bc8c4SAl Viro { 524756daf26SNeilBrown struct nameidata *now = current->nameidata; 525756daf26SNeilBrown 526756daf26SNeilBrown current->nameidata = old; 527756daf26SNeilBrown if (old) 528756daf26SNeilBrown old->total_link_count = now->total_link_count; 529756daf26SNeilBrown if (now->stack != now->internal) { 530756daf26SNeilBrown kfree(now->stack); 531756daf26SNeilBrown now->stack = now->internal; 532894bc8c4SAl Viro } 533894bc8c4SAl Viro } 534894bc8c4SAl Viro 535894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 536894bc8c4SAl Viro { 537e269f2a7SAl Viro struct saved *p = kmalloc(MAXSYMLINKS * sizeof(struct saved), 538894bc8c4SAl Viro GFP_KERNEL); 539894bc8c4SAl Viro if (unlikely(!p)) 540894bc8c4SAl Viro return -ENOMEM; 541894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 542894bc8c4SAl Viro nd->stack = p; 543894bc8c4SAl Viro return 0; 544894bc8c4SAl Viro } 545894bc8c4SAl Viro 546894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 547894bc8c4SAl Viro { 548da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 549894bc8c4SAl Viro return 0; 550894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 551894bc8c4SAl Viro return 0; 552894bc8c4SAl Viro return __nd_alloc_stack(nd); 553894bc8c4SAl Viro } 554894bc8c4SAl Viro 55519660af7SAl Viro /* 55631e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 55719660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 55819660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 55919660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 56019660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 56119660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 56219660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 56319660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 56431e6b01fSNick Piggin */ 56531e6b01fSNick Piggin 566e8bb73dfSAl Viro static void terminate_walk(struct nameidata *nd); 567e8bb73dfSAl Viro 56831e6b01fSNick Piggin /** 56919660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 57019660af7SAl Viro * @nd: nameidata pathwalk data 57119660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 57239191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 57331e6b01fSNick Piggin * 57419660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 57519660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 57619660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 57731e6b01fSNick Piggin */ 57819660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 57931e6b01fSNick Piggin { 58031e6b01fSNick Piggin struct fs_struct *fs = current->fs; 58131e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 58231e6b01fSNick Piggin 58331e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 584e5c832d5SLinus Torvalds 585e5c832d5SLinus Torvalds /* 58648a066e7SAl Viro * After legitimizing the bastards, terminate_walk() 58748a066e7SAl Viro * will do the right thing for non-RCU mode, and all our 58848a066e7SAl Viro * subsequent exit cases should rcu_read_unlock() 58948a066e7SAl Viro * before returning. Do vfsmount first; if dentry 59048a066e7SAl Viro * can't be legitimized, just set nd->path.dentry to NULL 59148a066e7SAl Viro * and rely on dput(NULL) being a no-op. 592e5c832d5SLinus Torvalds */ 59348a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) 594e5c832d5SLinus Torvalds return -ECHILD; 595e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 59615570086SLinus Torvalds 59748a066e7SAl Viro if (!lockref_get_not_dead(&parent->d_lockref)) { 59848a066e7SAl Viro nd->path.dentry = NULL; 599d870b4a1SAl Viro goto out; 60048a066e7SAl Viro } 60148a066e7SAl Viro 60215570086SLinus Torvalds /* 60315570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 60415570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 60515570086SLinus Torvalds * 60615570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 60715570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 60815570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 60915570086SLinus Torvalds * since we checked the sequence number of the parent after we got 61015570086SLinus Torvalds * the child sequence number. So we know the parent must still 61115570086SLinus Torvalds * be valid if the child sequence number is still valid. 61215570086SLinus Torvalds */ 61319660af7SAl Viro if (!dentry) { 614e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 615e5c832d5SLinus Torvalds goto out; 61619660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 61719660af7SAl Viro } else { 618e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 619e5c832d5SLinus Torvalds goto out; 620e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) 621e5c832d5SLinus Torvalds goto drop_dentry; 62219660af7SAl Viro } 623e5c832d5SLinus Torvalds 624e5c832d5SLinus Torvalds /* 625e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 626e5c832d5SLinus Torvalds * still valid and get it if required. 627e5c832d5SLinus Torvalds */ 628e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 629e5c832d5SLinus Torvalds spin_lock(&fs->lock); 630e5c832d5SLinus Torvalds if (nd->root.mnt != fs->root.mnt || nd->root.dentry != fs->root.dentry) 631e5c832d5SLinus Torvalds goto unlock_and_drop_dentry; 63231e6b01fSNick Piggin path_get(&nd->root); 63331e6b01fSNick Piggin spin_unlock(&fs->lock); 63431e6b01fSNick Piggin } 63531e6b01fSNick Piggin 6368b61e74fSAl Viro rcu_read_unlock(); 63731e6b01fSNick Piggin return 0; 63819660af7SAl Viro 639e5c832d5SLinus Torvalds unlock_and_drop_dentry: 64031e6b01fSNick Piggin spin_unlock(&fs->lock); 641e5c832d5SLinus Torvalds drop_dentry: 6428b61e74fSAl Viro rcu_read_unlock(); 643e5c832d5SLinus Torvalds dput(dentry); 644d0d27277SLinus Torvalds goto drop_root_mnt; 645e5c832d5SLinus Torvalds out: 6468b61e74fSAl Viro rcu_read_unlock(); 647d0d27277SLinus Torvalds drop_root_mnt: 648d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 649d0d27277SLinus Torvalds nd->root.mnt = NULL; 65031e6b01fSNick Piggin return -ECHILD; 65131e6b01fSNick Piggin } 65231e6b01fSNick Piggin 6534ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 65434286d66SNick Piggin { 6554ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 65634286d66SNick Piggin } 65734286d66SNick Piggin 6589f1fafeeSAl Viro /** 6599f1fafeeSAl Viro * complete_walk - successful completion of path walk 6609f1fafeeSAl Viro * @nd: pointer nameidata 66139159de2SJeff Layton * 6629f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 6639f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 6649f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 6659f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 6669f1fafeeSAl Viro * need to drop nd->path. 66739159de2SJeff Layton */ 6689f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 66939159de2SJeff Layton { 67016c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 67139159de2SJeff Layton int status; 67239159de2SJeff Layton 6739f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 6749f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6759f1fafeeSAl Viro nd->root.mnt = NULL; 676e8bb73dfSAl Viro if (unlikely(unlazy_walk(nd, NULL))) { 677e8bb73dfSAl Viro terminate_walk(nd); 67848a066e7SAl Viro return -ECHILD; 67948a066e7SAl Viro } 6809f1fafeeSAl Viro } 6819f1fafeeSAl Viro 68216c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 68339159de2SJeff Layton return 0; 68439159de2SJeff Layton 685ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 68616c2cd71SAl Viro return 0; 68716c2cd71SAl Viro 688ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 68939159de2SJeff Layton if (status > 0) 69039159de2SJeff Layton return 0; 69139159de2SJeff Layton 69216c2cd71SAl Viro if (!status) 69339159de2SJeff Layton status = -ESTALE; 69416c2cd71SAl Viro 695e8bb73dfSAl Viro terminate_walk(nd); 69639159de2SJeff Layton return status; 69739159de2SJeff Layton } 69839159de2SJeff Layton 6992a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 7002a737871SAl Viro { 701f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 7022a737871SAl Viro } 7032a737871SAl Viro 7047bd88377SAl Viro static __always_inline unsigned set_root_rcu(struct nameidata *nd) 70531e6b01fSNick Piggin { 70631e6b01fSNick Piggin struct fs_struct *fs = current->fs; 7077bd88377SAl Viro unsigned seq, res; 708c28cc364SNick Piggin 709c28cc364SNick Piggin do { 710c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 71131e6b01fSNick Piggin nd->root = fs->root; 7127bd88377SAl Viro res = __read_seqcount_begin(&nd->root.dentry->d_seq); 713c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 7147bd88377SAl Viro return res; 71531e6b01fSNick Piggin } 71631e6b01fSNick Piggin 7171d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 718051d3812SIan Kent { 719051d3812SIan Kent dput(path->dentry); 7204ac91378SJan Blunck if (path->mnt != nd->path.mnt) 721051d3812SIan Kent mntput(path->mnt); 722051d3812SIan Kent } 723051d3812SIan Kent 7247b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 7257b9337aaSNick Piggin struct nameidata *nd) 726051d3812SIan Kent { 72731e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 7284ac91378SJan Blunck dput(nd->path.dentry); 72931e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 7304ac91378SJan Blunck mntput(nd->path.mnt); 7319a229683SHuang Shijie } 73231e6b01fSNick Piggin nd->path.mnt = path->mnt; 7334ac91378SJan Blunck nd->path.dentry = path->dentry; 734051d3812SIan Kent } 735051d3812SIan Kent 736b5fb63c1SChristoph Hellwig /* 737b5fb63c1SChristoph Hellwig * Helper to directly jump to a known parsed path from ->follow_link, 738b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 739b5fb63c1SChristoph Hellwig */ 7406e77137bSAl Viro void nd_jump_link(struct path *path) 741b5fb63c1SChristoph Hellwig { 7426e77137bSAl Viro struct nameidata *nd = current->nameidata; 743b5fb63c1SChristoph Hellwig path_put(&nd->path); 744b5fb63c1SChristoph Hellwig 745b5fb63c1SChristoph Hellwig nd->path = *path; 746b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 747b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 748b5fb63c1SChristoph Hellwig } 749b5fb63c1SChristoph Hellwig 750b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 751574197e0SAl Viro { 75221c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 753b9ff4429SAl Viro struct inode *inode = last->link.dentry->d_inode; 754b9ff4429SAl Viro if (last->cookie && inode->i_op->put_link) 755b9ff4429SAl Viro inode->i_op->put_link(last->link.dentry, last->cookie); 756b9ff4429SAl Viro path_put(&last->link); 757574197e0SAl Viro } 758574197e0SAl Viro 759561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 760561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 761800179c9SKees Cook 762800179c9SKees Cook /** 763800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 76455852635SRandy Dunlap * @nd: nameidata pathwalk data 765800179c9SKees Cook * 766800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 767800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 768800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 769800179c9SKees Cook * processes from failing races against path names that may change out 770800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 771800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 772800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 773800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 774800179c9SKees Cook * 775800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 776800179c9SKees Cook */ 777fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 778800179c9SKees Cook { 779800179c9SKees Cook const struct inode *inode; 780800179c9SKees Cook const struct inode *parent; 781800179c9SKees Cook 782800179c9SKees Cook if (!sysctl_protected_symlinks) 783800179c9SKees Cook return 0; 784800179c9SKees Cook 785800179c9SKees Cook /* Allowed if owner and follower match. */ 7861cf2665bSAl Viro inode = nd->stack[0].link.dentry->d_inode; 78781abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 788800179c9SKees Cook return 0; 789800179c9SKees Cook 790800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 791800179c9SKees Cook parent = nd->path.dentry->d_inode; 792800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 793800179c9SKees Cook return 0; 794800179c9SKees Cook 795800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 79681abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 797800179c9SKees Cook return 0; 798800179c9SKees Cook 7991cf2665bSAl Viro audit_log_link_denied("follow_link", &nd->stack[0].link); 800800179c9SKees Cook return -EACCES; 801800179c9SKees Cook } 802800179c9SKees Cook 803800179c9SKees Cook /** 804800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 805800179c9SKees Cook * @inode: the source inode to hardlink from 806800179c9SKees Cook * 807800179c9SKees Cook * Return false if at least one of the following conditions: 808800179c9SKees Cook * - inode is not a regular file 809800179c9SKees Cook * - inode is setuid 810800179c9SKees Cook * - inode is setgid and group-exec 811800179c9SKees Cook * - access failure for read and write 812800179c9SKees Cook * 813800179c9SKees Cook * Otherwise returns true. 814800179c9SKees Cook */ 815800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 816800179c9SKees Cook { 817800179c9SKees Cook umode_t mode = inode->i_mode; 818800179c9SKees Cook 819800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 820800179c9SKees Cook if (!S_ISREG(mode)) 821800179c9SKees Cook return false; 822800179c9SKees Cook 823800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 824800179c9SKees Cook if (mode & S_ISUID) 825800179c9SKees Cook return false; 826800179c9SKees Cook 827800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 828800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 829800179c9SKees Cook return false; 830800179c9SKees Cook 831800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 832800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 833800179c9SKees Cook return false; 834800179c9SKees Cook 835800179c9SKees Cook return true; 836800179c9SKees Cook } 837800179c9SKees Cook 838800179c9SKees Cook /** 839800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 840800179c9SKees Cook * @link: the source to hardlink from 841800179c9SKees Cook * 842800179c9SKees Cook * Block hardlink when all of: 843800179c9SKees Cook * - sysctl_protected_hardlinks enabled 844800179c9SKees Cook * - fsuid does not match inode 845800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 846800179c9SKees Cook * - not CAP_FOWNER 847800179c9SKees Cook * 848800179c9SKees Cook * Returns 0 if successful, -ve on error. 849800179c9SKees Cook */ 850800179c9SKees Cook static int may_linkat(struct path *link) 851800179c9SKees Cook { 852800179c9SKees Cook const struct cred *cred; 853800179c9SKees Cook struct inode *inode; 854800179c9SKees Cook 855800179c9SKees Cook if (!sysctl_protected_hardlinks) 856800179c9SKees Cook return 0; 857800179c9SKees Cook 858800179c9SKees Cook cred = current_cred(); 859800179c9SKees Cook inode = link->dentry->d_inode; 860800179c9SKees Cook 861800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 862800179c9SKees Cook * otherwise, it must be a safe source. 863800179c9SKees Cook */ 86481abe27bSEric W. Biederman if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || 865800179c9SKees Cook capable(CAP_FOWNER)) 866800179c9SKees Cook return 0; 867800179c9SKees Cook 868a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 869800179c9SKees Cook return -EPERM; 870800179c9SKees Cook } 871800179c9SKees Cook 8723b2e7f75SAl Viro static __always_inline 8733b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 8741da177e4SLinus Torvalds { 875ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 8761cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 8770a959df5SAl Viro struct inode *inode = dentry->d_inode; 8786d7b5aaeSAl Viro int error; 8790a959df5SAl Viro const char *res; 8801da177e4SLinus Torvalds 881844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 882844a3917SAl Viro 883574197e0SAl Viro cond_resched(); 884574197e0SAl Viro 8853b2e7f75SAl Viro touch_atime(&last->link); 886cd4e91d3SAl Viro 88737882db0SNeilBrown error = security_inode_follow_link(dentry); 8886d7b5aaeSAl Viro if (error) 8896920a440SAl Viro return ERR_PTR(error); 89036f3b4f6SAl Viro 89186acdca1SAl Viro nd->last_type = LAST_BIND; 892d4dee48bSAl Viro res = inode->i_link; 893d4dee48bSAl Viro if (!res) { 8946e77137bSAl Viro res = inode->i_op->follow_link(dentry, &last->cookie); 895fab51e8aSAl Viro if (IS_ERR_OR_NULL(res)) { 8966920a440SAl Viro last->cookie = NULL; 897fab51e8aSAl Viro return res; 8980a959df5SAl Viro } 899fab51e8aSAl Viro } 900fab51e8aSAl Viro if (*res == '/') { 901fab51e8aSAl Viro if (!nd->root.mnt) 902fab51e8aSAl Viro set_root(nd); 903fab51e8aSAl Viro path_put(&nd->path); 904fab51e8aSAl Viro nd->path = nd->root; 905fab51e8aSAl Viro path_get(&nd->root); 906fab51e8aSAl Viro nd->inode = nd->path.dentry->d_inode; 907fab51e8aSAl Viro nd->flags |= LOOKUP_JUMPED; 908fab51e8aSAl Viro while (unlikely(*++res == '/')) 909fab51e8aSAl Viro ; 910fab51e8aSAl Viro } 911fab51e8aSAl Viro if (!*res) 912fab51e8aSAl Viro res = NULL; 9130a959df5SAl Viro return res; 9140a959df5SAl Viro } 9156d7b5aaeSAl Viro 91631e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 91731e6b01fSNick Piggin { 9180714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9190714a533SAl Viro struct mount *parent; 92031e6b01fSNick Piggin struct dentry *mountpoint; 92131e6b01fSNick Piggin 9220714a533SAl Viro parent = mnt->mnt_parent; 9230714a533SAl Viro if (&parent->mnt == path->mnt) 92431e6b01fSNick Piggin return 0; 925a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 92631e6b01fSNick Piggin path->dentry = mountpoint; 9270714a533SAl Viro path->mnt = &parent->mnt; 92831e6b01fSNick Piggin return 1; 92931e6b01fSNick Piggin } 93031e6b01fSNick Piggin 931f015f126SDavid Howells /* 932f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 933f015f126SDavid Howells * 934f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 935f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 936f015f126SDavid Howells * Up is towards /. 937f015f126SDavid Howells * 938f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 939f015f126SDavid Howells * root. 940f015f126SDavid Howells */ 941bab77ebfSAl Viro int follow_up(struct path *path) 9421da177e4SLinus Torvalds { 9430714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9440714a533SAl Viro struct mount *parent; 9451da177e4SLinus Torvalds struct dentry *mountpoint; 94699b7db7bSNick Piggin 94748a066e7SAl Viro read_seqlock_excl(&mount_lock); 9480714a533SAl Viro parent = mnt->mnt_parent; 9493c0a6163SAl Viro if (parent == mnt) { 95048a066e7SAl Viro read_sequnlock_excl(&mount_lock); 9511da177e4SLinus Torvalds return 0; 9521da177e4SLinus Torvalds } 9530714a533SAl Viro mntget(&parent->mnt); 954a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 95548a066e7SAl Viro read_sequnlock_excl(&mount_lock); 956bab77ebfSAl Viro dput(path->dentry); 957bab77ebfSAl Viro path->dentry = mountpoint; 958bab77ebfSAl Viro mntput(path->mnt); 9590714a533SAl Viro path->mnt = &parent->mnt; 9601da177e4SLinus Torvalds return 1; 9611da177e4SLinus Torvalds } 9624d359507SAl Viro EXPORT_SYMBOL(follow_up); 9631da177e4SLinus Torvalds 964b5c84bf6SNick Piggin /* 9659875cf80SDavid Howells * Perform an automount 9669875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 9679875cf80SDavid Howells * were called with. 9681da177e4SLinus Torvalds */ 969756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 9709875cf80SDavid Howells bool *need_mntput) 97131e6b01fSNick Piggin { 9729875cf80SDavid Howells struct vfsmount *mnt; 973ea5b778aSDavid Howells int err; 9749875cf80SDavid Howells 9759875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 9769875cf80SDavid Howells return -EREMOTE; 9779875cf80SDavid Howells 9780ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 9790ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 9800ec26fd0SMiklos Szeredi * the name. 9810ec26fd0SMiklos Szeredi * 9820ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 9835a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 9840ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 9850ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 9860ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 9870ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 9885a30d8a2SDavid Howells */ 989756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 990d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 9915a30d8a2SDavid Howells path->dentry->d_inode) 9929875cf80SDavid Howells return -EISDIR; 9930ec26fd0SMiklos Szeredi 994756daf26SNeilBrown nd->total_link_count++; 995756daf26SNeilBrown if (nd->total_link_count >= 40) 9969875cf80SDavid Howells return -ELOOP; 9979875cf80SDavid Howells 9989875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 9999875cf80SDavid Howells if (IS_ERR(mnt)) { 10009875cf80SDavid Howells /* 10019875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 10029875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 10039875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 10049875cf80SDavid Howells * 10059875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 10069875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 10079875cf80SDavid Howells * the path is inaccessible and we should say so. 10089875cf80SDavid Howells */ 1009756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 10109875cf80SDavid Howells return -EREMOTE; 10119875cf80SDavid Howells return PTR_ERR(mnt); 101231e6b01fSNick Piggin } 1013ea5b778aSDavid Howells 10149875cf80SDavid Howells if (!mnt) /* mount collision */ 10159875cf80SDavid Howells return 0; 10169875cf80SDavid Howells 10178aef1884SAl Viro if (!*need_mntput) { 10188aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 10198aef1884SAl Viro mntget(path->mnt); 10208aef1884SAl Viro *need_mntput = true; 10218aef1884SAl Viro } 102219a167afSAl Viro err = finish_automount(mnt, path); 1023ea5b778aSDavid Howells 1024ea5b778aSDavid Howells switch (err) { 1025ea5b778aSDavid Howells case -EBUSY: 1026ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 102719a167afSAl Viro return 0; 1028ea5b778aSDavid Howells case 0: 10298aef1884SAl Viro path_put(path); 10309875cf80SDavid Howells path->mnt = mnt; 10319875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 10329875cf80SDavid Howells return 0; 103319a167afSAl Viro default: 103419a167afSAl Viro return err; 10359875cf80SDavid Howells } 103619a167afSAl Viro 1037ea5b778aSDavid Howells } 10389875cf80SDavid Howells 10399875cf80SDavid Howells /* 10409875cf80SDavid Howells * Handle a dentry that is managed in some way. 1041cc53ce53SDavid Howells * - Flagged for transit management (autofs) 10429875cf80SDavid Howells * - Flagged as mountpoint 10439875cf80SDavid Howells * - Flagged as automount point 10449875cf80SDavid Howells * 10459875cf80SDavid Howells * This may only be called in refwalk mode. 10469875cf80SDavid Howells * 10479875cf80SDavid Howells * Serialization is taken care of in namespace.c 10489875cf80SDavid Howells */ 1049756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 10509875cf80SDavid Howells { 10518aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 10529875cf80SDavid Howells unsigned managed; 10539875cf80SDavid Howells bool need_mntput = false; 10548aef1884SAl Viro int ret = 0; 10559875cf80SDavid Howells 10569875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 10579875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 10589875cf80SDavid Howells * the components of that value change under us */ 10599875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 10609875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 10619875cf80SDavid Howells unlikely(managed != 0)) { 1062cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1063cc53ce53SDavid Howells * being held. */ 1064cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1065cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1066cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 10671aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1068cc53ce53SDavid Howells if (ret < 0) 10698aef1884SAl Viro break; 1070cc53ce53SDavid Howells } 1071cc53ce53SDavid Howells 10729875cf80SDavid Howells /* Transit to a mounted filesystem. */ 10739875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 10749875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10759875cf80SDavid Howells if (mounted) { 10769875cf80SDavid Howells dput(path->dentry); 10779875cf80SDavid Howells if (need_mntput) 1078463ffb2eSAl Viro mntput(path->mnt); 1079463ffb2eSAl Viro path->mnt = mounted; 1080463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 10819875cf80SDavid Howells need_mntput = true; 10829875cf80SDavid Howells continue; 1083463ffb2eSAl Viro } 1084463ffb2eSAl Viro 10859875cf80SDavid Howells /* Something is mounted on this dentry in another 10869875cf80SDavid Howells * namespace and/or whatever was mounted there in this 108748a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 108848a066e7SAl Viro * get it */ 10891da177e4SLinus Torvalds } 10909875cf80SDavid Howells 10919875cf80SDavid Howells /* Handle an automount point */ 10929875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1093756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 10949875cf80SDavid Howells if (ret < 0) 10958aef1884SAl Viro break; 10969875cf80SDavid Howells continue; 10979875cf80SDavid Howells } 10989875cf80SDavid Howells 10999875cf80SDavid Howells /* We didn't change the current path point */ 11009875cf80SDavid Howells break; 11019875cf80SDavid Howells } 11028aef1884SAl Viro 11038aef1884SAl Viro if (need_mntput && path->mnt == mnt) 11048aef1884SAl Viro mntput(path->mnt); 11058aef1884SAl Viro if (ret == -EISDIR) 11068aef1884SAl Viro ret = 0; 11078402752eSAl Viro if (need_mntput) 11088402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 11098402752eSAl Viro if (unlikely(ret < 0)) 11108402752eSAl Viro path_put_conditional(path, nd); 11118402752eSAl Viro return ret; 11121da177e4SLinus Torvalds } 11131da177e4SLinus Torvalds 1114cc53ce53SDavid Howells int follow_down_one(struct path *path) 11151da177e4SLinus Torvalds { 11161da177e4SLinus Torvalds struct vfsmount *mounted; 11171da177e4SLinus Torvalds 11181c755af4SAl Viro mounted = lookup_mnt(path); 11191da177e4SLinus Torvalds if (mounted) { 11209393bd07SAl Viro dput(path->dentry); 11219393bd07SAl Viro mntput(path->mnt); 11229393bd07SAl Viro path->mnt = mounted; 11239393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 11241da177e4SLinus Torvalds return 1; 11251da177e4SLinus Torvalds } 11261da177e4SLinus Torvalds return 0; 11271da177e4SLinus Torvalds } 11284d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 11291da177e4SLinus Torvalds 1130b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 113162a7375eSIan Kent { 1132b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1133b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 113462a7375eSIan Kent } 113562a7375eSIan Kent 11369875cf80SDavid Howells /* 1137287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1138287548e4SAl Viro * we meet a managed dentry that would need blocking. 11399875cf80SDavid Howells */ 11409875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1141287548e4SAl Viro struct inode **inode) 11429875cf80SDavid Howells { 114362a7375eSIan Kent for (;;) { 1144c7105365SAl Viro struct mount *mounted; 114562a7375eSIan Kent /* 114662a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 114762a7375eSIan Kent * that wants to block transit. 114862a7375eSIan Kent */ 1149b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1150b8faf035SNeilBrown case -ECHILD: 1151b8faf035SNeilBrown default: 1152ab90911fSDavid Howells return false; 1153b8faf035SNeilBrown case -EISDIR: 1154b8faf035SNeilBrown return true; 1155b8faf035SNeilBrown case 0: 1156b8faf035SNeilBrown break; 1157b8faf035SNeilBrown } 115862a7375eSIan Kent 115962a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1160b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 116162a7375eSIan Kent 1162474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 11639875cf80SDavid Howells if (!mounted) 11649875cf80SDavid Howells break; 1165c7105365SAl Viro path->mnt = &mounted->mnt; 1166c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1167a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 11689875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 116959430262SLinus Torvalds /* 117059430262SLinus Torvalds * Update the inode too. We don't need to re-check the 117159430262SLinus Torvalds * dentry sequence number here after this d_inode read, 117259430262SLinus Torvalds * because a mount-point is always pinned. 117359430262SLinus Torvalds */ 117459430262SLinus Torvalds *inode = path->dentry->d_inode; 11759875cf80SDavid Howells } 1176f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1177b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1178287548e4SAl Viro } 1179287548e4SAl Viro 118031e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 118131e6b01fSNick Piggin { 11824023bfc9SAl Viro struct inode *inode = nd->inode; 11837bd88377SAl Viro if (!nd->root.mnt) 118431e6b01fSNick Piggin set_root_rcu(nd); 118531e6b01fSNick Piggin 118631e6b01fSNick Piggin while (1) { 118731e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 118831e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 118931e6b01fSNick Piggin break; 119031e6b01fSNick Piggin } 119131e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 119231e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 119331e6b01fSNick Piggin struct dentry *parent = old->d_parent; 119431e6b01fSNick Piggin unsigned seq; 119531e6b01fSNick Piggin 11964023bfc9SAl Viro inode = parent->d_inode; 119731e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 119831e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1199ef7562d5SAl Viro goto failed; 120031e6b01fSNick Piggin nd->path.dentry = parent; 120131e6b01fSNick Piggin nd->seq = seq; 120231e6b01fSNick Piggin break; 120331e6b01fSNick Piggin } 120431e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 120531e6b01fSNick Piggin break; 12064023bfc9SAl Viro inode = nd->path.dentry->d_inode; 120731e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 120831e6b01fSNick Piggin } 1209b37199e6SAl Viro while (d_mountpoint(nd->path.dentry)) { 1210b37199e6SAl Viro struct mount *mounted; 1211b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1212b37199e6SAl Viro if (!mounted) 1213b37199e6SAl Viro break; 1214b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1215b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 12164023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1217b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1218f5be3e29SAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1219b37199e6SAl Viro goto failed; 1220b37199e6SAl Viro } 12214023bfc9SAl Viro nd->inode = inode; 122231e6b01fSNick Piggin return 0; 1223ef7562d5SAl Viro 1224ef7562d5SAl Viro failed: 1225ef7562d5SAl Viro return -ECHILD; 122631e6b01fSNick Piggin } 122731e6b01fSNick Piggin 12289875cf80SDavid Howells /* 1229cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1230cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1231cc53ce53SDavid Howells * caller is permitted to proceed or not. 1232cc53ce53SDavid Howells */ 12337cc90cc3SAl Viro int follow_down(struct path *path) 1234cc53ce53SDavid Howells { 1235cc53ce53SDavid Howells unsigned managed; 1236cc53ce53SDavid Howells int ret; 1237cc53ce53SDavid Howells 1238cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1239cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1240cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1241cc53ce53SDavid Howells * being held. 1242cc53ce53SDavid Howells * 1243cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1244cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1245cc53ce53SDavid Howells * other than its daemon the right to mount on its 1246cc53ce53SDavid Howells * superstructure. 1247cc53ce53SDavid Howells * 1248cc53ce53SDavid Howells * The filesystem may sleep at this point. 1249cc53ce53SDavid Howells */ 1250cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1251cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1252cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1253ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 12541aed3e42SAl Viro path->dentry, false); 1255cc53ce53SDavid Howells if (ret < 0) 1256cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1257cc53ce53SDavid Howells } 1258cc53ce53SDavid Howells 1259cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1260cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1261cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1262cc53ce53SDavid Howells if (!mounted) 1263cc53ce53SDavid Howells break; 1264cc53ce53SDavid Howells dput(path->dentry); 1265cc53ce53SDavid Howells mntput(path->mnt); 1266cc53ce53SDavid Howells path->mnt = mounted; 1267cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1268cc53ce53SDavid Howells continue; 1269cc53ce53SDavid Howells } 1270cc53ce53SDavid Howells 1271cc53ce53SDavid Howells /* Don't handle automount points here */ 1272cc53ce53SDavid Howells break; 1273cc53ce53SDavid Howells } 1274cc53ce53SDavid Howells return 0; 1275cc53ce53SDavid Howells } 12764d359507SAl Viro EXPORT_SYMBOL(follow_down); 1277cc53ce53SDavid Howells 1278cc53ce53SDavid Howells /* 12799875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 12809875cf80SDavid Howells */ 12819875cf80SDavid Howells static void follow_mount(struct path *path) 12829875cf80SDavid Howells { 12839875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 12849875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12859875cf80SDavid Howells if (!mounted) 12869875cf80SDavid Howells break; 12879875cf80SDavid Howells dput(path->dentry); 12889875cf80SDavid Howells mntput(path->mnt); 12899875cf80SDavid Howells path->mnt = mounted; 12909875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 12919875cf80SDavid Howells } 12929875cf80SDavid Howells } 12939875cf80SDavid Howells 129431e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 12951da177e4SLinus Torvalds { 12967bd88377SAl Viro if (!nd->root.mnt) 12972a737871SAl Viro set_root(nd); 1298e518ddb7SAndreas Mohr 12991da177e4SLinus Torvalds while(1) { 13004ac91378SJan Blunck struct dentry *old = nd->path.dentry; 13011da177e4SLinus Torvalds 13022a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 13032a737871SAl Viro nd->path.mnt == nd->root.mnt) { 13041da177e4SLinus Torvalds break; 13051da177e4SLinus Torvalds } 13064ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 13073088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 13083088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 13091da177e4SLinus Torvalds dput(old); 13101da177e4SLinus Torvalds break; 13111da177e4SLinus Torvalds } 13123088dd70SAl Viro if (!follow_up(&nd->path)) 13131da177e4SLinus Torvalds break; 13141da177e4SLinus Torvalds } 131579ed0226SAl Viro follow_mount(&nd->path); 131631e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 13171da177e4SLinus Torvalds } 13181da177e4SLinus Torvalds 13191da177e4SLinus Torvalds /* 1320bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1321bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1322bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1323bad61189SMiklos Szeredi * 1324bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1325baa03890SNick Piggin */ 1326bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1327201f956eSAl Viro unsigned int flags, bool *need_lookup) 1328baa03890SNick Piggin { 1329baa03890SNick Piggin struct dentry *dentry; 1330bad61189SMiklos Szeredi int error; 1331baa03890SNick Piggin 1332bad61189SMiklos Szeredi *need_lookup = false; 1333bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1334bad61189SMiklos Szeredi if (dentry) { 133539e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1336201f956eSAl Viro error = d_revalidate(dentry, flags); 1337bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1338bad61189SMiklos Szeredi if (error < 0) { 1339bad61189SMiklos Szeredi dput(dentry); 1340bad61189SMiklos Szeredi return ERR_PTR(error); 13415542aa2fSEric W. Biederman } else { 13425542aa2fSEric W. Biederman d_invalidate(dentry); 1343bad61189SMiklos Szeredi dput(dentry); 1344bad61189SMiklos Szeredi dentry = NULL; 1345bad61189SMiklos Szeredi } 1346bad61189SMiklos Szeredi } 1347bad61189SMiklos Szeredi } 1348bad61189SMiklos Szeredi } 1349baa03890SNick Piggin 1350bad61189SMiklos Szeredi if (!dentry) { 1351bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1352baa03890SNick Piggin if (unlikely(!dentry)) 1353baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1354baa03890SNick Piggin 1355bad61189SMiklos Szeredi *need_lookup = true; 1356baa03890SNick Piggin } 1357baa03890SNick Piggin return dentry; 1358baa03890SNick Piggin } 1359baa03890SNick Piggin 1360baa03890SNick Piggin /* 136113a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 136213a2c3beSJ. Bruce Fields * unhashed. 1363bad61189SMiklos Szeredi * 1364bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 136544396f4bSJosef Bacik */ 1366bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 136772bd866aSAl Viro unsigned int flags) 136844396f4bSJosef Bacik { 136944396f4bSJosef Bacik struct dentry *old; 137044396f4bSJosef Bacik 137144396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1372bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1373e188dc02SMiklos Szeredi dput(dentry); 137444396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1375e188dc02SMiklos Szeredi } 137644396f4bSJosef Bacik 137772bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 137844396f4bSJosef Bacik if (unlikely(old)) { 137944396f4bSJosef Bacik dput(dentry); 138044396f4bSJosef Bacik dentry = old; 138144396f4bSJosef Bacik } 138244396f4bSJosef Bacik return dentry; 138344396f4bSJosef Bacik } 138444396f4bSJosef Bacik 1385a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 138672bd866aSAl Viro struct dentry *base, unsigned int flags) 1387a3255546SAl Viro { 1388bad61189SMiklos Szeredi bool need_lookup; 1389a3255546SAl Viro struct dentry *dentry; 1390a3255546SAl Viro 139172bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1392bad61189SMiklos Szeredi if (!need_lookup) 1393a3255546SAl Viro return dentry; 1394bad61189SMiklos Szeredi 139572bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1396a3255546SAl Viro } 1397a3255546SAl Viro 139844396f4bSJosef Bacik /* 13991da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 14001da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 14011da177e4SLinus Torvalds * It _is_ time-critical. 14021da177e4SLinus Torvalds */ 1403e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 140431e6b01fSNick Piggin struct path *path, struct inode **inode) 14051da177e4SLinus Torvalds { 14064ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 140731e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 14085a18fff2SAl Viro int need_reval = 1; 14095a18fff2SAl Viro int status = 1; 14109875cf80SDavid Howells int err; 14119875cf80SDavid Howells 14123cac260aSAl Viro /* 1413b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1414b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1415b04f784eSNick Piggin * do the non-racy lookup, below. 1416b04f784eSNick Piggin */ 141731e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 141831e6b01fSNick Piggin unsigned seq; 1419766c4cbfSAl Viro bool negative; 1420da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 14215a18fff2SAl Viro if (!dentry) 14225a18fff2SAl Viro goto unlazy; 14235a18fff2SAl Viro 142412f8ad4bSLinus Torvalds /* 142512f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 142612f8ad4bSLinus Torvalds * the dentry name information from lookup. 142712f8ad4bSLinus Torvalds */ 142812f8ad4bSLinus Torvalds *inode = dentry->d_inode; 1429766c4cbfSAl Viro negative = d_is_negative(dentry); 143012f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 143112f8ad4bSLinus Torvalds return -ECHILD; 1432766c4cbfSAl Viro if (negative) 1433766c4cbfSAl Viro return -ENOENT; 143412f8ad4bSLinus Torvalds 143512f8ad4bSLinus Torvalds /* 143612f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 143712f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 143812f8ad4bSLinus Torvalds * 143912f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 144012f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 144112f8ad4bSLinus Torvalds */ 144231e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 144331e6b01fSNick Piggin return -ECHILD; 144431e6b01fSNick Piggin nd->seq = seq; 14455a18fff2SAl Viro 144624643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 14474ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14485a18fff2SAl Viro if (unlikely(status <= 0)) { 14495a18fff2SAl Viro if (status != -ECHILD) 14505a18fff2SAl Viro need_reval = 0; 14515a18fff2SAl Viro goto unlazy; 14525a18fff2SAl Viro } 145324643087SAl Viro } 145431e6b01fSNick Piggin path->mnt = mnt; 145531e6b01fSNick Piggin path->dentry = dentry; 1456b8faf035SNeilBrown if (likely(__follow_mount_rcu(nd, path, inode))) 14579875cf80SDavid Howells return 0; 14585a18fff2SAl Viro unlazy: 145919660af7SAl Viro if (unlazy_walk(nd, dentry)) 14605a18fff2SAl Viro return -ECHILD; 14615a18fff2SAl Viro } else { 1462e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 146324643087SAl Viro } 14645a18fff2SAl Viro 146581e6f520SAl Viro if (unlikely(!dentry)) 146681e6f520SAl Viro goto need_lookup; 14675a18fff2SAl Viro 14685a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 14694ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14705a18fff2SAl Viro if (unlikely(status <= 0)) { 14715a18fff2SAl Viro if (status < 0) { 14725a18fff2SAl Viro dput(dentry); 14735a18fff2SAl Viro return status; 14745a18fff2SAl Viro } 14755542aa2fSEric W. Biederman d_invalidate(dentry); 14765a18fff2SAl Viro dput(dentry); 147781e6f520SAl Viro goto need_lookup; 14785a18fff2SAl Viro } 1479697f514dSMiklos Szeredi 1480766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1481766c4cbfSAl Viro dput(dentry); 1482766c4cbfSAl Viro return -ENOENT; 1483766c4cbfSAl Viro } 14841da177e4SLinus Torvalds path->mnt = mnt; 14851da177e4SLinus Torvalds path->dentry = dentry; 1486756daf26SNeilBrown err = follow_managed(path, nd); 14878402752eSAl Viro if (likely(!err)) 148831e6b01fSNick Piggin *inode = path->dentry->d_inode; 14898402752eSAl Viro return err; 149081e6f520SAl Viro 149181e6f520SAl Viro need_lookup: 1492697f514dSMiklos Szeredi return 1; 1493697f514dSMiklos Szeredi } 1494697f514dSMiklos Szeredi 1495697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1496cc2a5271SAl Viro static int lookup_slow(struct nameidata *nd, struct path *path) 1497697f514dSMiklos Szeredi { 1498697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1499697f514dSMiklos Szeredi 1500697f514dSMiklos Szeredi parent = nd->path.dentry; 150181e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 150281e6f520SAl Viro 150381e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 1504cc2a5271SAl Viro dentry = __lookup_hash(&nd->last, parent, nd->flags); 150581e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 150681e6f520SAl Viro if (IS_ERR(dentry)) 150781e6f520SAl Viro return PTR_ERR(dentry); 1508697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1509697f514dSMiklos Szeredi path->dentry = dentry; 15108402752eSAl Viro return follow_managed(path, nd); 15111da177e4SLinus Torvalds } 15121da177e4SLinus Torvalds 151352094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 151452094c8aSAl Viro { 151552094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 15164ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 151752094c8aSAl Viro if (err != -ECHILD) 151852094c8aSAl Viro return err; 151919660af7SAl Viro if (unlazy_walk(nd, NULL)) 152052094c8aSAl Viro return -ECHILD; 152152094c8aSAl Viro } 15224ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 152352094c8aSAl Viro } 152452094c8aSAl Viro 15259856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 15269856fa1bSAl Viro { 15279856fa1bSAl Viro if (type == LAST_DOTDOT) { 15289856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 152970291aecSAl Viro return follow_dotdot_rcu(nd); 15309856fa1bSAl Viro } else 15319856fa1bSAl Viro follow_dotdot(nd); 15329856fa1bSAl Viro } 15339856fa1bSAl Viro return 0; 15349856fa1bSAl Viro } 15359856fa1bSAl Viro 1536951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1537951361f9SAl Viro { 1538951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1539951361f9SAl Viro path_put(&nd->path); 1540951361f9SAl Viro } else { 1541951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 15425b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1543951361f9SAl Viro nd->root.mnt = NULL; 15448b61e74fSAl Viro rcu_read_unlock(); 1545951361f9SAl Viro } 154615439726SAl Viro while (unlikely(nd->depth)) 154715439726SAl Viro put_link(nd); 1548951361f9SAl Viro } 1549951361f9SAl Viro 1550d63ff28fSAl Viro static int pick_link(struct nameidata *nd, struct path *link) 1551d63ff28fSAl Viro { 1552626de996SAl Viro int error; 15531cf2665bSAl Viro struct saved *last; 1554756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1555626de996SAl Viro path_to_nameidata(link, nd); 1556626de996SAl Viro return -ELOOP; 1557626de996SAl Viro } 1558d63ff28fSAl Viro if (nd->flags & LOOKUP_RCU) { 1559d63ff28fSAl Viro if (unlikely(nd->path.mnt != link->mnt || 1560d63ff28fSAl Viro unlazy_walk(nd, link->dentry))) { 1561d63ff28fSAl Viro return -ECHILD; 1562d63ff28fSAl Viro } 1563d63ff28fSAl Viro } 1564cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1565cd179f44SAl Viro mntget(link->mnt); 1566626de996SAl Viro error = nd_alloc_stack(nd); 1567626de996SAl Viro if (unlikely(error)) { 1568cd179f44SAl Viro path_put(link); 1569626de996SAl Viro return error; 1570626de996SAl Viro } 1571626de996SAl Viro 1572ab104923SAl Viro last = nd->stack + nd->depth++; 15731cf2665bSAl Viro last->link = *link; 1574ab104923SAl Viro last->cookie = NULL; 1575d63ff28fSAl Viro return 1; 1576d63ff28fSAl Viro } 1577d63ff28fSAl Viro 15783ddcd056SLinus Torvalds /* 15793ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 15803ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 15813ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 15823ddcd056SLinus Torvalds * for the common case. 15833ddcd056SLinus Torvalds */ 1584d63ff28fSAl Viro static inline int should_follow_link(struct nameidata *nd, struct path *link, int follow) 15853ddcd056SLinus Torvalds { 1586d63ff28fSAl Viro if (likely(!d_is_symlink(link->dentry))) 1587d63ff28fSAl Viro return 0; 1588d63ff28fSAl Viro if (!follow) 1589d63ff28fSAl Viro return 0; 1590d63ff28fSAl Viro return pick_link(nd, link); 15913ddcd056SLinus Torvalds } 15923ddcd056SLinus Torvalds 15934693a547SAl Viro enum {WALK_GET = 1, WALK_PUT = 2}; 15944693a547SAl Viro 15954693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1596ce57dfc1SAl Viro { 1597caa85634SAl Viro struct path path; 1598ce57dfc1SAl Viro struct inode *inode; 1599ce57dfc1SAl Viro int err; 1600ce57dfc1SAl Viro /* 1601ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1602ce57dfc1SAl Viro * to be able to know about the current root directory and 1603ce57dfc1SAl Viro * parent relationships. 1604ce57dfc1SAl Viro */ 16054693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 16064693a547SAl Viro err = handle_dots(nd, nd->last_type); 16074693a547SAl Viro if (flags & WALK_PUT) 16084693a547SAl Viro put_link(nd); 16094693a547SAl Viro return err; 16104693a547SAl Viro } 1611caa85634SAl Viro err = lookup_fast(nd, &path, &inode); 1612ce57dfc1SAl Viro if (unlikely(err)) { 1613697f514dSMiklos Szeredi if (err < 0) 1614f0a9ba70SAl Viro return err; 1615697f514dSMiklos Szeredi 1616caa85634SAl Viro err = lookup_slow(nd, &path); 1617697f514dSMiklos Szeredi if (err < 0) 1618f0a9ba70SAl Viro return err; 1619697f514dSMiklos Szeredi 1620caa85634SAl Viro inode = path.dentry->d_inode; 1621697f514dSMiklos Szeredi err = -ENOENT; 1622caa85634SAl Viro if (d_is_negative(path.dentry)) 1623697f514dSMiklos Szeredi goto out_path_put; 1624766c4cbfSAl Viro } 1625697f514dSMiklos Szeredi 16264693a547SAl Viro if (flags & WALK_PUT) 16274693a547SAl Viro put_link(nd); 1628d63ff28fSAl Viro err = should_follow_link(nd, &path, flags & WALK_GET); 1629d63ff28fSAl Viro if (unlikely(err)) 1630d63ff28fSAl Viro return err; 1631caa85634SAl Viro path_to_nameidata(&path, nd); 1632ce57dfc1SAl Viro nd->inode = inode; 1633ce57dfc1SAl Viro return 0; 1634697f514dSMiklos Szeredi 1635697f514dSMiklos Szeredi out_path_put: 1636caa85634SAl Viro path_to_nameidata(&path, nd); 1637697f514dSMiklos Szeredi return err; 1638ce57dfc1SAl Viro } 1639ce57dfc1SAl Viro 16401da177e4SLinus Torvalds /* 1641bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1642bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1643bfcfaa77SLinus Torvalds * 1644bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1645bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1646bfcfaa77SLinus Torvalds * fast. 1647bfcfaa77SLinus Torvalds * 1648bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1649bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1650bfcfaa77SLinus Torvalds * crossing operation. 1651bfcfaa77SLinus Torvalds * 1652bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1653bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1654bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1655bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1656bfcfaa77SLinus Torvalds */ 1657bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1658bfcfaa77SLinus Torvalds 1659f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1660bfcfaa77SLinus Torvalds 1661f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1662bfcfaa77SLinus Torvalds 1663bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1664bfcfaa77SLinus Torvalds { 166599d263d4SLinus Torvalds return hash_64(hash, 32); 1666bfcfaa77SLinus Torvalds } 1667bfcfaa77SLinus Torvalds 1668bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1669bfcfaa77SLinus Torvalds 1670bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1671bfcfaa77SLinus Torvalds 1672bfcfaa77SLinus Torvalds #endif 1673bfcfaa77SLinus Torvalds 1674bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1675bfcfaa77SLinus Torvalds { 1676bfcfaa77SLinus Torvalds unsigned long a, mask; 1677bfcfaa77SLinus Torvalds unsigned long hash = 0; 1678bfcfaa77SLinus Torvalds 1679bfcfaa77SLinus Torvalds for (;;) { 1680e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1681bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1682bfcfaa77SLinus Torvalds break; 1683bfcfaa77SLinus Torvalds hash += a; 1684f132c5beSAl Viro hash *= 9; 1685bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1686bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1687bfcfaa77SLinus Torvalds if (!len) 1688bfcfaa77SLinus Torvalds goto done; 1689bfcfaa77SLinus Torvalds } 1690a5c21dceSWill Deacon mask = bytemask_from_count(len); 1691bfcfaa77SLinus Torvalds hash += mask & a; 1692bfcfaa77SLinus Torvalds done: 1693bfcfaa77SLinus Torvalds return fold_hash(hash); 1694bfcfaa77SLinus Torvalds } 1695bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1696bfcfaa77SLinus Torvalds 1697bfcfaa77SLinus Torvalds /* 1698bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1699d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1700bfcfaa77SLinus Torvalds */ 1701d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1702bfcfaa77SLinus Torvalds { 170336126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 170436126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1705bfcfaa77SLinus Torvalds 1706bfcfaa77SLinus Torvalds hash = a = 0; 1707bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1708bfcfaa77SLinus Torvalds do { 1709bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1710bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1711e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 171236126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 171336126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1714bfcfaa77SLinus Torvalds 171536126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 171636126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 171736126f8fSLinus Torvalds 171836126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 171936126f8fSLinus Torvalds 172036126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 17219226b5b4SLinus Torvalds len += find_zero(mask); 1722d6bb3e90SLinus Torvalds return hashlen_create(fold_hash(hash), len); 1723bfcfaa77SLinus Torvalds } 1724bfcfaa77SLinus Torvalds 1725bfcfaa77SLinus Torvalds #else 1726bfcfaa77SLinus Torvalds 17270145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 17280145acc2SLinus Torvalds { 17290145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 17300145acc2SLinus Torvalds while (len--) 17310145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 17320145acc2SLinus Torvalds return end_name_hash(hash); 17330145acc2SLinus Torvalds } 1734ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 17350145acc2SLinus Torvalds 17363ddcd056SLinus Torvalds /* 1737200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1738200e9ef7SLinus Torvalds * one character. 1739200e9ef7SLinus Torvalds */ 1740d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1741200e9ef7SLinus Torvalds { 1742200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1743200e9ef7SLinus Torvalds unsigned long len = 0, c; 1744200e9ef7SLinus Torvalds 1745200e9ef7SLinus Torvalds c = (unsigned char)*name; 1746200e9ef7SLinus Torvalds do { 1747200e9ef7SLinus Torvalds len++; 1748200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1749200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1750200e9ef7SLinus Torvalds } while (c && c != '/'); 1751d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 1752200e9ef7SLinus Torvalds } 1753200e9ef7SLinus Torvalds 1754bfcfaa77SLinus Torvalds #endif 1755bfcfaa77SLinus Torvalds 1756200e9ef7SLinus Torvalds /* 17571da177e4SLinus Torvalds * Name resolution. 1758ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1759ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 17601da177e4SLinus Torvalds * 1761ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1762ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 17631da177e4SLinus Torvalds */ 17646de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 17651da177e4SLinus Torvalds { 17661da177e4SLinus Torvalds int err; 17671da177e4SLinus Torvalds 17681da177e4SLinus Torvalds while (*name=='/') 17691da177e4SLinus Torvalds name++; 17701da177e4SLinus Torvalds if (!*name) 17719e18f10aSAl Viro return 0; 17721da177e4SLinus Torvalds 17731da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 17741da177e4SLinus Torvalds for(;;) { 1775d6bb3e90SLinus Torvalds u64 hash_len; 1776fe479a58SAl Viro int type; 17771da177e4SLinus Torvalds 177852094c8aSAl Viro err = may_lookup(nd); 17791da177e4SLinus Torvalds if (err) 17801da177e4SLinus Torvalds break; 17811da177e4SLinus Torvalds 1782d6bb3e90SLinus Torvalds hash_len = hash_name(name); 17831da177e4SLinus Torvalds 1784fe479a58SAl Viro type = LAST_NORM; 1785d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 1786fe479a58SAl Viro case 2: 1787200e9ef7SLinus Torvalds if (name[1] == '.') { 1788fe479a58SAl Viro type = LAST_DOTDOT; 178916c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 179016c2cd71SAl Viro } 1791fe479a58SAl Viro break; 1792fe479a58SAl Viro case 1: 1793fe479a58SAl Viro type = LAST_DOT; 1794fe479a58SAl Viro } 17955a202bcdSAl Viro if (likely(type == LAST_NORM)) { 17965a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 179716c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 17985a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 1799a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 1800da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 18015a202bcdSAl Viro if (err < 0) 18025a202bcdSAl Viro break; 1803d6bb3e90SLinus Torvalds hash_len = this.hash_len; 1804d6bb3e90SLinus Torvalds name = this.name; 18055a202bcdSAl Viro } 18065a202bcdSAl Viro } 1807fe479a58SAl Viro 1808d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 1809d6bb3e90SLinus Torvalds nd->last.name = name; 18105f4a6a69SAl Viro nd->last_type = type; 18115f4a6a69SAl Viro 1812d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 1813d6bb3e90SLinus Torvalds if (!*name) 1814bdf6cbf1SAl Viro goto OK; 1815200e9ef7SLinus Torvalds /* 1816200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1817200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1818200e9ef7SLinus Torvalds */ 1819200e9ef7SLinus Torvalds do { 1820d6bb3e90SLinus Torvalds name++; 1821d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 18228620c238SAl Viro if (unlikely(!*name)) { 18238620c238SAl Viro OK: 18248620c238SAl Viro /* called from path_init(), done */ 18258620c238SAl Viro if (!nd->depth) 18268620c238SAl Viro return 0; 18278620c238SAl Viro name = nd->stack[nd->depth - 1].name; 18288620c238SAl Viro /* called from trailing_symlink(), done */ 18298620c238SAl Viro if (!name) 18308620c238SAl Viro return 0; 18318620c238SAl Viro /* last component of nested symlink */ 18324693a547SAl Viro err = walk_component(nd, WALK_GET | WALK_PUT); 18338620c238SAl Viro } else { 18344693a547SAl Viro err = walk_component(nd, WALK_GET); 18358620c238SAl Viro } 1836ce57dfc1SAl Viro if (err < 0) 1837f0a9ba70SAl Viro break; 1838fe479a58SAl Viro 1839ce57dfc1SAl Viro if (err) { 1840626de996SAl Viro const char *s = get_link(nd); 18415a460275SAl Viro 1842172a39a0SAl Viro if (unlikely(IS_ERR(s))) { 1843172a39a0SAl Viro err = PTR_ERR(s); 18441bc4b813SAl Viro break; 1845172a39a0SAl Viro } 1846172a39a0SAl Viro err = 0; 184712b09578SAl Viro if (unlikely(!s)) { 184812b09578SAl Viro /* jumped */ 1849b9ff4429SAl Viro put_link(nd); 185012b09578SAl Viro } else { 1851071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 185232cd7468SAl Viro name = s; 18539e18f10aSAl Viro continue; 185448c8b0c5SAl Viro } 185531e6b01fSNick Piggin } 185644b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 18573ddcd056SLinus Torvalds err = -ENOTDIR; 18583ddcd056SLinus Torvalds break; 18595f4a6a69SAl Viro } 1860ce57dfc1SAl Viro } 1861951361f9SAl Viro terminate_walk(nd); 18621da177e4SLinus Torvalds return err; 186307681481SAl Viro } 18641da177e4SLinus Torvalds 18656e8a1f87SAl Viro static int path_init(int dfd, const struct filename *name, unsigned int flags, 18665e53084dSAl Viro struct nameidata *nd) 186731e6b01fSNick Piggin { 186831e6b01fSNick Piggin int retval = 0; 1869fd2f7cb5SAl Viro const char *s = name->name; 187031e6b01fSNick Piggin 187131e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 1872980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 187331e6b01fSNick Piggin nd->depth = 0; 18745b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 1875b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 1876b18825a7SDavid Howells struct inode *inode = root->d_inode; 1877fd2f7cb5SAl Viro if (*s) { 187844b1d530SMiklos Szeredi if (!d_can_lookup(root)) 18795b6ca027SAl Viro return -ENOTDIR; 18805b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 18815b6ca027SAl Viro if (retval) 18825b6ca027SAl Viro return retval; 188373d049a4SAl Viro } 18845b6ca027SAl Viro nd->path = nd->root; 18855b6ca027SAl Viro nd->inode = inode; 18865b6ca027SAl Viro if (flags & LOOKUP_RCU) { 18878b61e74fSAl Viro rcu_read_lock(); 18885b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 188948a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 18905b6ca027SAl Viro } else { 18915b6ca027SAl Viro path_get(&nd->path); 18925b6ca027SAl Viro } 1893d465887fSAl Viro goto done; 18945b6ca027SAl Viro } 18955b6ca027SAl Viro 189631e6b01fSNick Piggin nd->root.mnt = NULL; 189731e6b01fSNick Piggin 189848a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 1899fd2f7cb5SAl Viro if (*s == '/') { 1900e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 19018b61e74fSAl Viro rcu_read_lock(); 19027bd88377SAl Viro nd->seq = set_root_rcu(nd); 1903e41f7d4eSAl Viro } else { 1904e41f7d4eSAl Viro set_root(nd); 1905e41f7d4eSAl Viro path_get(&nd->root); 1906e41f7d4eSAl Viro } 190731e6b01fSNick Piggin nd->path = nd->root; 190831e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1909e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 191031e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1911c28cc364SNick Piggin unsigned seq; 191231e6b01fSNick Piggin 19138b61e74fSAl Viro rcu_read_lock(); 191431e6b01fSNick Piggin 1915c28cc364SNick Piggin do { 1916c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 191731e6b01fSNick Piggin nd->path = fs->pwd; 1918c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1919c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1920e41f7d4eSAl Viro } else { 1921e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1922e41f7d4eSAl Viro } 192331e6b01fSNick Piggin } else { 1924582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 19252903ff01SAl Viro struct fd f = fdget_raw(dfd); 192631e6b01fSNick Piggin struct dentry *dentry; 192731e6b01fSNick Piggin 19282903ff01SAl Viro if (!f.file) 19292903ff01SAl Viro return -EBADF; 193031e6b01fSNick Piggin 19312903ff01SAl Viro dentry = f.file->f_path.dentry; 193231e6b01fSNick Piggin 1933fd2f7cb5SAl Viro if (*s) { 193444b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 19352903ff01SAl Viro fdput(f); 19362903ff01SAl Viro return -ENOTDIR; 1937f52e0c11SAl Viro } 19382903ff01SAl Viro } 19392903ff01SAl Viro 19402903ff01SAl Viro nd->path = f.file->f_path; 1941e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 19428b61e74fSAl Viro rcu_read_lock(); 194334a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 194434a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 19455590ff0dSUlrich Drepper } else { 19462903ff01SAl Viro path_get(&nd->path); 194734a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 19481da177e4SLinus Torvalds } 194934a26b99SAl Viro fdput(f); 195034a26b99SAl Viro goto done; 1951e41f7d4eSAl Viro } 1952e41f7d4eSAl Viro 195331e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 19544023bfc9SAl Viro if (!(flags & LOOKUP_RCU)) 1955d465887fSAl Viro goto done; 19564023bfc9SAl Viro if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) 1957d465887fSAl Viro goto done; 19584023bfc9SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 19594023bfc9SAl Viro nd->root.mnt = NULL; 19604023bfc9SAl Viro rcu_read_unlock(); 19614023bfc9SAl Viro return -ECHILD; 1962d465887fSAl Viro done: 1963756daf26SNeilBrown nd->total_link_count = 0; 1964dc7af8dcSAl Viro return link_path_walk(s, nd); 19659b4a9b14SAl Viro } 19669b4a9b14SAl Viro 1967893b7775SAl Viro static void path_cleanup(struct nameidata *nd) 1968893b7775SAl Viro { 1969893b7775SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 1970893b7775SAl Viro path_put(&nd->root); 1971893b7775SAl Viro nd->root.mnt = NULL; 1972893b7775SAl Viro } 19739b4a9b14SAl Viro } 19749b4a9b14SAl Viro 19751d8e03d3SAl Viro static int trailing_symlink(struct nameidata *nd) 197695fa25d9SAl Viro { 197795fa25d9SAl Viro const char *s; 1978fec2fa24SAl Viro int error = may_follow_link(nd); 1979b5cd3397SAl Viro if (unlikely(error)) { 1980b5cd3397SAl Viro terminate_walk(nd); 198195fa25d9SAl Viro return error; 1982b5cd3397SAl Viro } 198395fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 1984fab51e8aSAl Viro nd->stack[0].name = NULL; 19853b2e7f75SAl Viro s = get_link(nd); 19861bc4b813SAl Viro if (unlikely(IS_ERR(s))) { 19871bc4b813SAl Viro terminate_walk(nd); 198895fa25d9SAl Viro return PTR_ERR(s); 19891bc4b813SAl Viro } 19909ea57b72SAl Viro if (unlikely(!s)) 199195fa25d9SAl Viro return 0; 19928eff733aSAl Viro return link_path_walk(s, nd); 199395fa25d9SAl Viro } 199495fa25d9SAl Viro 1995caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 1996bd92d7feSAl Viro { 1997f0a9ba70SAl Viro int err; 1998bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1999bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2000bd92d7feSAl Viro 2001bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 20024693a547SAl Viro err = walk_component(nd, 20034693a547SAl Viro nd->flags & LOOKUP_FOLLOW 20044693a547SAl Viro ? nd->depth 20054693a547SAl Viro ? WALK_PUT | WALK_GET 20064693a547SAl Viro : WALK_GET 20074693a547SAl Viro : 0); 2008f0a9ba70SAl Viro if (err < 0) 2009f0a9ba70SAl Viro terminate_walk(nd); 2010f0a9ba70SAl Viro return err; 2011bd92d7feSAl Viro } 2012bd92d7feSAl Viro 20139b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 20145eb6b495SAl Viro static int path_lookupat(int dfd, const struct filename *name, 20159b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 20169b4a9b14SAl Viro { 2017bd92d7feSAl Viro int err; 201831e6b01fSNick Piggin 201931e6b01fSNick Piggin /* 202031e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 202131e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 202231e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 202331e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 202431e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 202531e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 202631e6b01fSNick Piggin * analogue, foo_rcu(). 202731e6b01fSNick Piggin * 202831e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 202931e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 203031e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 203131e6b01fSNick Piggin * be able to complete). 203231e6b01fSNick Piggin */ 20336e8a1f87SAl Viro err = path_init(dfd, name, flags, nd); 20348bcb77faSAl Viro if (!err) { 2035191d7f73SAl Viro while ((err = lookup_last(nd)) > 0) { 20361d8e03d3SAl Viro err = trailing_symlink(nd); 20376d7b5aaeSAl Viro if (err) 20386d7b5aaeSAl Viro break; 2039bd92d7feSAl Viro } 2040bd92d7feSAl Viro } 2041ee0827cdSAl Viro 20429f1fafeeSAl Viro if (!err) 20439f1fafeeSAl Viro err = complete_walk(nd); 2044bd92d7feSAl Viro 2045bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 204644b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 2047bd92d7feSAl Viro path_put(&nd->path); 2048bd23a539SAl Viro err = -ENOTDIR; 2049bd92d7feSAl Viro } 2050bd92d7feSAl Viro } 205116c2cd71SAl Viro 2052893b7775SAl Viro path_cleanup(nd); 2053bd92d7feSAl Viro return err; 205431e6b01fSNick Piggin } 205531e6b01fSNick Piggin 2056873f1eedSJeff Layton static int filename_lookup(int dfd, struct filename *name, 2057873f1eedSJeff Layton unsigned int flags, struct nameidata *nd) 2058873f1eedSJeff Layton { 2059894bc8c4SAl Viro int retval; 2060756daf26SNeilBrown struct nameidata *saved_nd = set_nameidata(nd); 2061894bc8c4SAl Viro 2062894bc8c4SAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 2063873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 20645eb6b495SAl Viro retval = path_lookupat(dfd, name, flags, nd); 2065873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 20665eb6b495SAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 2067873f1eedSJeff Layton 2068873f1eedSJeff Layton if (likely(!retval)) 2069adb5c247SJeff Layton audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); 2070756daf26SNeilBrown restore_nameidata(saved_nd); 2071873f1eedSJeff Layton return retval; 2072873f1eedSJeff Layton } 2073873f1eedSJeff Layton 20748bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 20758bcb77faSAl Viro static int path_parentat(int dfd, const struct filename *name, 20768bcb77faSAl Viro unsigned int flags, struct nameidata *nd) 20778bcb77faSAl Viro { 20788bcb77faSAl Viro int err = path_init(dfd, name, flags | LOOKUP_PARENT, nd); 20798bcb77faSAl Viro if (!err) 20808bcb77faSAl Viro err = complete_walk(nd); 20818bcb77faSAl Viro path_cleanup(nd); 20828bcb77faSAl Viro return err; 20838bcb77faSAl Viro } 20848bcb77faSAl Viro 20858bcb77faSAl Viro static int filename_parentat(int dfd, struct filename *name, 20868bcb77faSAl Viro unsigned int flags, struct nameidata *nd) 20878bcb77faSAl Viro { 20888bcb77faSAl Viro int retval; 20898bcb77faSAl Viro struct nameidata *saved_nd = set_nameidata(nd); 20908bcb77faSAl Viro 20918bcb77faSAl Viro retval = path_parentat(dfd, name, flags | LOOKUP_RCU, nd); 20928bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 20938bcb77faSAl Viro retval = path_parentat(dfd, name, flags, nd); 20948bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 20958bcb77faSAl Viro retval = path_parentat(dfd, name, flags | LOOKUP_REVAL, nd); 20968bcb77faSAl Viro 20978bcb77faSAl Viro if (likely(!retval)) 20988bcb77faSAl Viro audit_inode(name, nd->path.dentry, LOOKUP_PARENT); 20998bcb77faSAl Viro restore_nameidata(saved_nd); 21008bcb77faSAl Viro return retval; 21018bcb77faSAl Viro } 21028bcb77faSAl Viro 210379714f72SAl Viro /* does lookup, returns the object with parent locked */ 210479714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 21055590ff0dSUlrich Drepper { 210651689104SPaul Moore struct filename *filename = getname_kernel(name); 210779714f72SAl Viro struct nameidata nd; 210879714f72SAl Viro struct dentry *d; 210951689104SPaul Moore int err; 211051689104SPaul Moore 211151689104SPaul Moore if (IS_ERR(filename)) 211251689104SPaul Moore return ERR_CAST(filename); 211351689104SPaul Moore 21148bcb77faSAl Viro err = filename_parentat(AT_FDCWD, filename, 0, &nd); 211551689104SPaul Moore if (err) { 211651689104SPaul Moore d = ERR_PTR(err); 211751689104SPaul Moore goto out; 211851689104SPaul Moore } 211979714f72SAl Viro if (nd.last_type != LAST_NORM) { 212079714f72SAl Viro path_put(&nd.path); 212151689104SPaul Moore d = ERR_PTR(-EINVAL); 212251689104SPaul Moore goto out; 212379714f72SAl Viro } 212479714f72SAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 21251e0ea001SAl Viro d = __lookup_hash(&nd.last, nd.path.dentry, 0); 212679714f72SAl Viro if (IS_ERR(d)) { 212779714f72SAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 212879714f72SAl Viro path_put(&nd.path); 212951689104SPaul Moore goto out; 213079714f72SAl Viro } 213179714f72SAl Viro *path = nd.path; 213251689104SPaul Moore out: 213351689104SPaul Moore putname(filename); 213479714f72SAl Viro return d; 21355590ff0dSUlrich Drepper } 21365590ff0dSUlrich Drepper 2137d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2138d1811465SAl Viro { 2139d1811465SAl Viro struct nameidata nd; 214074eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 214174eb8cc5SAl Viro int res = PTR_ERR(filename); 214274eb8cc5SAl Viro 214374eb8cc5SAl Viro if (!IS_ERR(filename)) { 214474eb8cc5SAl Viro res = filename_lookup(AT_FDCWD, filename, flags, &nd); 214574eb8cc5SAl Viro putname(filename); 2146d1811465SAl Viro if (!res) 2147d1811465SAl Viro *path = nd.path; 214874eb8cc5SAl Viro } 2149d1811465SAl Viro return res; 2150d1811465SAl Viro } 21514d359507SAl Viro EXPORT_SYMBOL(kern_path); 2152d1811465SAl Viro 215316f18200SJosef 'Jeff' Sipek /** 215416f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 215516f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 215616f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 215716f18200SJosef 'Jeff' Sipek * @name: pointer to file name 215816f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2159e0a01249SAl Viro * @path: pointer to struct path to fill 216016f18200SJosef 'Jeff' Sipek */ 216116f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 216216f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2163e0a01249SAl Viro struct path *path) 216416f18200SJosef 'Jeff' Sipek { 216574eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 216674eb8cc5SAl Viro int err = PTR_ERR(filename); 216774eb8cc5SAl Viro 216874eb8cc5SAl Viro BUG_ON(flags & LOOKUP_PARENT); 216974eb8cc5SAl Viro 217074eb8cc5SAl Viro /* the first argument of filename_lookup() is ignored with LOOKUP_ROOT */ 217174eb8cc5SAl Viro if (!IS_ERR(filename)) { 2172e0a01249SAl Viro struct nameidata nd; 2173e0a01249SAl Viro nd.root.dentry = dentry; 2174e0a01249SAl Viro nd.root.mnt = mnt; 217574eb8cc5SAl Viro err = filename_lookup(AT_FDCWD, filename, 217674eb8cc5SAl Viro flags | LOOKUP_ROOT, &nd); 2177e0a01249SAl Viro if (!err) 2178e0a01249SAl Viro *path = nd.path; 217974eb8cc5SAl Viro putname(filename); 218074eb8cc5SAl Viro } 2181e0a01249SAl Viro return err; 218216f18200SJosef 'Jeff' Sipek } 21834d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 218416f18200SJosef 'Jeff' Sipek 2185eead1911SChristoph Hellwig /** 2186a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2187eead1911SChristoph Hellwig * @name: pathname component to lookup 2188eead1911SChristoph Hellwig * @base: base directory to lookup from 2189eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2190eead1911SChristoph Hellwig * 2191a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 21929e7543e9SAl Viro * not be called by generic code. 2193eead1911SChristoph Hellwig */ 2194057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2195057f6c01SJames Morris { 2196057f6c01SJames Morris struct qstr this; 21976a96ba54SAl Viro unsigned int c; 2198cda309deSMiklos Szeredi int err; 2199057f6c01SJames Morris 22002f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 22012f9092e1SDavid Woodhouse 22026a96ba54SAl Viro this.name = name; 22036a96ba54SAl Viro this.len = len; 22040145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 22056a96ba54SAl Viro if (!len) 22066a96ba54SAl Viro return ERR_PTR(-EACCES); 22076a96ba54SAl Viro 220821d8a15aSAl Viro if (unlikely(name[0] == '.')) { 220921d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 221021d8a15aSAl Viro return ERR_PTR(-EACCES); 221121d8a15aSAl Viro } 221221d8a15aSAl Viro 22136a96ba54SAl Viro while (len--) { 22146a96ba54SAl Viro c = *(const unsigned char *)name++; 22156a96ba54SAl Viro if (c == '/' || c == '\0') 22166a96ba54SAl Viro return ERR_PTR(-EACCES); 22176a96ba54SAl Viro } 22185a202bcdSAl Viro /* 22195a202bcdSAl Viro * See if the low-level filesystem might want 22205a202bcdSAl Viro * to use its own hash.. 22215a202bcdSAl Viro */ 22225a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2223da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 22245a202bcdSAl Viro if (err < 0) 22255a202bcdSAl Viro return ERR_PTR(err); 22265a202bcdSAl Viro } 2227eead1911SChristoph Hellwig 2228cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2229cda309deSMiklos Szeredi if (err) 2230cda309deSMiklos Szeredi return ERR_PTR(err); 2231cda309deSMiklos Szeredi 223272bd866aSAl Viro return __lookup_hash(&this, base, 0); 2233057f6c01SJames Morris } 22344d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2235057f6c01SJames Morris 22361fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 22371fa1e7f6SAndy Whitcroft struct path *path, int *empty) 22381da177e4SLinus Torvalds { 22392d8f3038SAl Viro struct nameidata nd; 224091a27b2aSJeff Layton struct filename *tmp = getname_flags(name, flags, empty); 22411da177e4SLinus Torvalds int err = PTR_ERR(tmp); 22421da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 22432d8f3038SAl Viro 22442d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 22452d8f3038SAl Viro 2246873f1eedSJeff Layton err = filename_lookup(dfd, tmp, flags, &nd); 22471da177e4SLinus Torvalds putname(tmp); 22482d8f3038SAl Viro if (!err) 22492d8f3038SAl Viro *path = nd.path; 22501da177e4SLinus Torvalds } 22511da177e4SLinus Torvalds return err; 22521da177e4SLinus Torvalds } 22531da177e4SLinus Torvalds 22541fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 22551fa1e7f6SAndy Whitcroft struct path *path) 22561fa1e7f6SAndy Whitcroft { 2257f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 22581fa1e7f6SAndy Whitcroft } 22594d359507SAl Viro EXPORT_SYMBOL(user_path_at); 22601fa1e7f6SAndy Whitcroft 2261873f1eedSJeff Layton /* 2262873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2263873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2264873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2265873f1eedSJeff Layton * path-walking is complete. 2266873f1eedSJeff Layton */ 226791a27b2aSJeff Layton static struct filename * 2268f5beed75SAl Viro user_path_parent(int dfd, const char __user *path, 2269f5beed75SAl Viro struct path *parent, 2270f5beed75SAl Viro struct qstr *last, 2271f5beed75SAl Viro int *type, 22729e790bd6SJeff Layton unsigned int flags) 22732ad94ae6SAl Viro { 2274f5beed75SAl Viro struct nameidata nd; 227591a27b2aSJeff Layton struct filename *s = getname(path); 22762ad94ae6SAl Viro int error; 22772ad94ae6SAl Viro 22789e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 22799e790bd6SJeff Layton flags &= LOOKUP_REVAL; 22809e790bd6SJeff Layton 22812ad94ae6SAl Viro if (IS_ERR(s)) 228291a27b2aSJeff Layton return s; 22832ad94ae6SAl Viro 22848bcb77faSAl Viro error = filename_parentat(dfd, s, flags, &nd); 228591a27b2aSJeff Layton if (error) { 22862ad94ae6SAl Viro putname(s); 228791a27b2aSJeff Layton return ERR_PTR(error); 228891a27b2aSJeff Layton } 2289f5beed75SAl Viro *parent = nd.path; 2290f5beed75SAl Viro *last = nd.last; 2291f5beed75SAl Viro *type = nd.last_type; 22922ad94ae6SAl Viro 229391a27b2aSJeff Layton return s; 22942ad94ae6SAl Viro } 22952ad94ae6SAl Viro 22968033426eSJeff Layton /** 2297197df04cSAl Viro * mountpoint_last - look up last component for umount 22988033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 22998033426eSJeff Layton * @path: pointer to container for result 23008033426eSJeff Layton * 23018033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 23028033426eSJeff Layton * need to resolve the path without doing any revalidation. 23038033426eSJeff Layton * 23048033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 23058033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 23068033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 23078033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 23088033426eSJeff Layton * bogus and it doesn't exist. 23098033426eSJeff Layton * 23108033426eSJeff Layton * Returns: 23118033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 23128033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 23138033426eSJeff Layton * put in this case. 23148033426eSJeff Layton * 23158033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 23168033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 23178033426eSJeff Layton * The nd->path reference will also be put. 23188033426eSJeff Layton * 23198033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 23208033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 23218033426eSJeff Layton * to the link, and nd->path will *not* be put. 23228033426eSJeff Layton */ 23238033426eSJeff Layton static int 2324197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 23258033426eSJeff Layton { 23268033426eSJeff Layton int error = 0; 23278033426eSJeff Layton struct dentry *dentry; 23288033426eSJeff Layton struct dentry *dir = nd->path.dentry; 23298033426eSJeff Layton 233035759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 233135759521SAl Viro if (nd->flags & LOOKUP_RCU) { 233235759521SAl Viro if (unlazy_walk(nd, NULL)) { 23338033426eSJeff Layton error = -ECHILD; 233435759521SAl Viro goto out; 233535759521SAl Viro } 23368033426eSJeff Layton } 23378033426eSJeff Layton 23388033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 23398033426eSJeff Layton 23408033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 23418033426eSJeff Layton error = handle_dots(nd, nd->last_type); 234235759521SAl Viro if (error) 234335759521SAl Viro goto out; 23448033426eSJeff Layton dentry = dget(nd->path.dentry); 234535759521SAl Viro goto done; 23468033426eSJeff Layton } 23478033426eSJeff Layton 23488033426eSJeff Layton mutex_lock(&dir->d_inode->i_mutex); 23498033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 23508033426eSJeff Layton if (!dentry) { 23518033426eSJeff Layton /* 23528033426eSJeff Layton * No cached dentry. Mounted dentries are pinned in the cache, 23538033426eSJeff Layton * so that means that this dentry is probably a symlink or the 23548033426eSJeff Layton * path doesn't actually point to a mounted dentry. 23558033426eSJeff Layton */ 23568033426eSJeff Layton dentry = d_alloc(dir, &nd->last); 23578033426eSJeff Layton if (!dentry) { 23588033426eSJeff Layton error = -ENOMEM; 2359bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 236035759521SAl Viro goto out; 23618033426eSJeff Layton } 236235759521SAl Viro dentry = lookup_real(dir->d_inode, dentry, nd->flags); 236335759521SAl Viro error = PTR_ERR(dentry); 2364bcceeebaSDave Jones if (IS_ERR(dentry)) { 2365bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 236635759521SAl Viro goto out; 23678033426eSJeff Layton } 2368bcceeebaSDave Jones } 23698033426eSJeff Layton mutex_unlock(&dir->d_inode->i_mutex); 23708033426eSJeff Layton 237135759521SAl Viro done: 2372698934dfSDavid Howells if (d_is_negative(dentry)) { 23738033426eSJeff Layton error = -ENOENT; 23748033426eSJeff Layton dput(dentry); 237535759521SAl Viro goto out; 237635759521SAl Viro } 2377191d7f73SAl Viro if (nd->depth) 2378191d7f73SAl Viro put_link(nd); 23798033426eSJeff Layton path->dentry = dentry; 2380295dc39dSVasily Averin path->mnt = nd->path.mnt; 2381d63ff28fSAl Viro error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW); 2382d63ff28fSAl Viro if (unlikely(error)) { 2383d63ff28fSAl Viro if (error < 0) 2384d63ff28fSAl Viro goto out; 2385d63ff28fSAl Viro return error; 2386caa85634SAl Viro } 2387295dc39dSVasily Averin mntget(path->mnt); 23888033426eSJeff Layton follow_mount(path); 238935759521SAl Viro error = 0; 239035759521SAl Viro out: 23918033426eSJeff Layton terminate_walk(nd); 23928033426eSJeff Layton return error; 23938033426eSJeff Layton } 23948033426eSJeff Layton 23958033426eSJeff Layton /** 2396197df04cSAl Viro * path_mountpoint - look up a path to be umounted 23978033426eSJeff Layton * @dfd: directory file descriptor to start walk from 23988033426eSJeff Layton * @name: full pathname to walk 2399606d6fe3SRandy Dunlap * @path: pointer to container for result 24008033426eSJeff Layton * @flags: lookup flags 24018033426eSJeff Layton * 24028033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2403606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 24048033426eSJeff Layton */ 24058033426eSJeff Layton static int 2406668696dcSAl Viro path_mountpoint(int dfd, const struct filename *name, struct path *path, 240746afd6f6SAl Viro struct nameidata *nd, unsigned int flags) 24088033426eSJeff Layton { 240946afd6f6SAl Viro int err = path_init(dfd, name, flags, nd); 24108033426eSJeff Layton if (unlikely(err)) 2411115cbfdcSAl Viro goto out; 24128033426eSJeff Layton 2413191d7f73SAl Viro while ((err = mountpoint_last(nd, path)) > 0) { 24141d8e03d3SAl Viro err = trailing_symlink(nd); 24158033426eSJeff Layton if (err) 24168033426eSJeff Layton break; 24178033426eSJeff Layton } 24188033426eSJeff Layton out: 241946afd6f6SAl Viro path_cleanup(nd); 24208033426eSJeff Layton return err; 24218033426eSJeff Layton } 24228033426eSJeff Layton 24232d864651SAl Viro static int 2424668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 24252d864651SAl Viro unsigned int flags) 24262d864651SAl Viro { 2427756daf26SNeilBrown struct nameidata nd, *saved; 2428cbaab2dbSAl Viro int error; 2429668696dcSAl Viro if (IS_ERR(name)) 2430668696dcSAl Viro return PTR_ERR(name); 2431756daf26SNeilBrown saved = set_nameidata(&nd); 243246afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_RCU); 24332d864651SAl Viro if (unlikely(error == -ECHILD)) 243446afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags); 24352d864651SAl Viro if (unlikely(error == -ESTALE)) 243646afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_REVAL); 24372d864651SAl Viro if (likely(!error)) 2438668696dcSAl Viro audit_inode(name, path->dentry, 0); 2439756daf26SNeilBrown restore_nameidata(saved); 2440668696dcSAl Viro putname(name); 24412d864651SAl Viro return error; 24422d864651SAl Viro } 24432d864651SAl Viro 24448033426eSJeff Layton /** 2445197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 24468033426eSJeff Layton * @dfd: directory file descriptor 24478033426eSJeff Layton * @name: pathname from userland 24488033426eSJeff Layton * @flags: lookup flags 24498033426eSJeff Layton * @path: pointer to container to hold result 24508033426eSJeff Layton * 24518033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 24528033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 24538033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 24548033426eSJeff Layton * and avoid revalidating the last component. 24558033426eSJeff Layton * 24568033426eSJeff Layton * Returns 0 and populates "path" on success. 24578033426eSJeff Layton */ 24588033426eSJeff Layton int 2459197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 24608033426eSJeff Layton struct path *path) 24618033426eSJeff Layton { 2462cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 24638033426eSJeff Layton } 24648033426eSJeff Layton 24652d864651SAl Viro int 24662d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 24672d864651SAl Viro unsigned int flags) 24682d864651SAl Viro { 2469cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 24702d864651SAl Viro } 24712d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 24722d864651SAl Viro 2473cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 24741da177e4SLinus Torvalds { 24758e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2476da9592edSDavid Howells 24778e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 24781da177e4SLinus Torvalds return 0; 24798e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 24801da177e4SLinus Torvalds return 0; 248123adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 24821da177e4SLinus Torvalds } 2483cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 24841da177e4SLinus Torvalds 24851da177e4SLinus Torvalds /* 24861da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 24871da177e4SLinus Torvalds * whether the type of victim is right. 24881da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 24891da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 24901da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 24911da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 24921da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 24931da177e4SLinus Torvalds * a. be owner of dir, or 24941da177e4SLinus Torvalds * b. be owner of victim, or 24951da177e4SLinus Torvalds * c. have CAP_FOWNER capability 24961da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 24971da177e4SLinus Torvalds * links pointing to it. 24981da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 24991da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 25001da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 25011da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 25021da177e4SLinus Torvalds * nfs_async_unlink(). 25031da177e4SLinus Torvalds */ 2504b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 25051da177e4SLinus Torvalds { 2506b18825a7SDavid Howells struct inode *inode = victim->d_inode; 25071da177e4SLinus Torvalds int error; 25081da177e4SLinus Torvalds 2509b18825a7SDavid Howells if (d_is_negative(victim)) 25101da177e4SLinus Torvalds return -ENOENT; 2511b18825a7SDavid Howells BUG_ON(!inode); 25121da177e4SLinus Torvalds 25131da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 25144fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 25151da177e4SLinus Torvalds 2516f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 25171da177e4SLinus Torvalds if (error) 25181da177e4SLinus Torvalds return error; 25191da177e4SLinus Torvalds if (IS_APPEND(dir)) 25201da177e4SLinus Torvalds return -EPERM; 2521b18825a7SDavid Howells 2522b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2523b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 25241da177e4SLinus Torvalds return -EPERM; 25251da177e4SLinus Torvalds if (isdir) { 252644b1d530SMiklos Szeredi if (!d_is_dir(victim)) 25271da177e4SLinus Torvalds return -ENOTDIR; 25281da177e4SLinus Torvalds if (IS_ROOT(victim)) 25291da177e4SLinus Torvalds return -EBUSY; 253044b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 25311da177e4SLinus Torvalds return -EISDIR; 25321da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25331da177e4SLinus Torvalds return -ENOENT; 25341da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 25351da177e4SLinus Torvalds return -EBUSY; 25361da177e4SLinus Torvalds return 0; 25371da177e4SLinus Torvalds } 25381da177e4SLinus Torvalds 25391da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 25401da177e4SLinus Torvalds * dir. 25411da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 25421da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 25431da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 25441da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 25451da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 25461da177e4SLinus Torvalds */ 2547a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 25481da177e4SLinus Torvalds { 254914e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 25501da177e4SLinus Torvalds if (child->d_inode) 25511da177e4SLinus Torvalds return -EEXIST; 25521da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25531da177e4SLinus Torvalds return -ENOENT; 2554f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 25551da177e4SLinus Torvalds } 25561da177e4SLinus Torvalds 25571da177e4SLinus Torvalds /* 25581da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 25591da177e4SLinus Torvalds */ 25601da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 25611da177e4SLinus Torvalds { 25621da177e4SLinus Torvalds struct dentry *p; 25631da177e4SLinus Torvalds 25641da177e4SLinus Torvalds if (p1 == p2) { 2565f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 25661da177e4SLinus Torvalds return NULL; 25671da177e4SLinus Torvalds } 25681da177e4SLinus Torvalds 2569a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25701da177e4SLinus Torvalds 2571e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2572e2761a11SOGAWA Hirofumi if (p) { 2573f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2574f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 25751da177e4SLinus Torvalds return p; 25761da177e4SLinus Torvalds } 25771da177e4SLinus Torvalds 2578e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2579e2761a11SOGAWA Hirofumi if (p) { 2580f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2581f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 25821da177e4SLinus Torvalds return p; 25831da177e4SLinus Torvalds } 25841da177e4SLinus Torvalds 2585f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2586d1b72cc6SMiklos Szeredi mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); 25871da177e4SLinus Torvalds return NULL; 25881da177e4SLinus Torvalds } 25894d359507SAl Viro EXPORT_SYMBOL(lock_rename); 25901da177e4SLinus Torvalds 25911da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 25921da177e4SLinus Torvalds { 25931b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 25941da177e4SLinus Torvalds if (p1 != p2) { 25951b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2596a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25971da177e4SLinus Torvalds } 25981da177e4SLinus Torvalds } 25994d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 26001da177e4SLinus Torvalds 26014acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2602312b63fbSAl Viro bool want_excl) 26031da177e4SLinus Torvalds { 2604a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 26051da177e4SLinus Torvalds if (error) 26061da177e4SLinus Torvalds return error; 26071da177e4SLinus Torvalds 2608acfa4380SAl Viro if (!dir->i_op->create) 26091da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 26101da177e4SLinus Torvalds mode &= S_IALLUGO; 26111da177e4SLinus Torvalds mode |= S_IFREG; 26121da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 26131da177e4SLinus Torvalds if (error) 26141da177e4SLinus Torvalds return error; 2615312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2616a74574aaSStephen Smalley if (!error) 2617f38aa942SAmy Griffis fsnotify_create(dir, dentry); 26181da177e4SLinus Torvalds return error; 26191da177e4SLinus Torvalds } 26204d359507SAl Viro EXPORT_SYMBOL(vfs_create); 26211da177e4SLinus Torvalds 262273d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 26231da177e4SLinus Torvalds { 26243fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 26251da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 26261da177e4SLinus Torvalds int error; 26271da177e4SLinus Torvalds 2628bcda7652SAl Viro /* O_PATH? */ 2629bcda7652SAl Viro if (!acc_mode) 2630bcda7652SAl Viro return 0; 2631bcda7652SAl Viro 26321da177e4SLinus Torvalds if (!inode) 26331da177e4SLinus Torvalds return -ENOENT; 26341da177e4SLinus Torvalds 2635c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2636c8fe8f30SChristoph Hellwig case S_IFLNK: 26371da177e4SLinus Torvalds return -ELOOP; 2638c8fe8f30SChristoph Hellwig case S_IFDIR: 2639c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 26401da177e4SLinus Torvalds return -EISDIR; 2641c8fe8f30SChristoph Hellwig break; 2642c8fe8f30SChristoph Hellwig case S_IFBLK: 2643c8fe8f30SChristoph Hellwig case S_IFCHR: 26443fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 26451da177e4SLinus Torvalds return -EACCES; 2646c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2647c8fe8f30SChristoph Hellwig case S_IFIFO: 2648c8fe8f30SChristoph Hellwig case S_IFSOCK: 26491da177e4SLinus Torvalds flag &= ~O_TRUNC; 2650c8fe8f30SChristoph Hellwig break; 26514a3fd211SDave Hansen } 2652b41572e9SDave Hansen 26533fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2654b41572e9SDave Hansen if (error) 2655b41572e9SDave Hansen return error; 26566146f0d5SMimi Zohar 26571da177e4SLinus Torvalds /* 26581da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 26591da177e4SLinus Torvalds */ 26601da177e4SLinus Torvalds if (IS_APPEND(inode)) { 26618737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 26627715b521SAl Viro return -EPERM; 26631da177e4SLinus Torvalds if (flag & O_TRUNC) 26647715b521SAl Viro return -EPERM; 26651da177e4SLinus Torvalds } 26661da177e4SLinus Torvalds 26671da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 26682e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 26697715b521SAl Viro return -EPERM; 26701da177e4SLinus Torvalds 2671f3c7691eSJ. Bruce Fields return 0; 26727715b521SAl Viro } 26737715b521SAl Viro 2674e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 26757715b521SAl Viro { 2676e1181ee6SJeff Layton struct path *path = &filp->f_path; 26777715b521SAl Viro struct inode *inode = path->dentry->d_inode; 26787715b521SAl Viro int error = get_write_access(inode); 26791da177e4SLinus Torvalds if (error) 26807715b521SAl Viro return error; 26811da177e4SLinus Torvalds /* 26821da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 26831da177e4SLinus Torvalds */ 2684d7a06983SJeff Layton error = locks_verify_locked(filp); 2685be6d3e56SKentaro Takeda if (!error) 2686ea0d3ab2STetsuo Handa error = security_path_truncate(path); 26871da177e4SLinus Torvalds if (!error) { 26887715b521SAl Viro error = do_truncate(path->dentry, 0, 2689d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2690e1181ee6SJeff Layton filp); 26911da177e4SLinus Torvalds } 26921da177e4SLinus Torvalds put_write_access(inode); 2693acd0c935SMimi Zohar return error; 26941da177e4SLinus Torvalds } 26951da177e4SLinus Torvalds 2696d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2697d57999e1SDave Hansen { 26988a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 26998a5e929dSAl Viro flag--; 2700d57999e1SDave Hansen return flag; 2701d57999e1SDave Hansen } 2702d57999e1SDave Hansen 2703d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2704d18e9008SMiklos Szeredi { 2705d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2706d18e9008SMiklos Szeredi if (error) 2707d18e9008SMiklos Szeredi return error; 2708d18e9008SMiklos Szeredi 2709d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2710d18e9008SMiklos Szeredi if (error) 2711d18e9008SMiklos Szeredi return error; 2712d18e9008SMiklos Szeredi 2713d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2714d18e9008SMiklos Szeredi } 2715d18e9008SMiklos Szeredi 27161acf0af9SDavid Howells /* 27171acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 27181acf0af9SDavid Howells * dentry. 27191acf0af9SDavid Howells * 27201acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 27211acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 27221acf0af9SDavid Howells * 27231acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 27241acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 27251acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 27261acf0af9SDavid Howells * 27271acf0af9SDavid Howells * Returns an error code otherwise. 27281acf0af9SDavid Howells */ 27292675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 273030d90494SAl Viro struct path *path, struct file *file, 2731015c3bbcSMiklos Szeredi const struct open_flags *op, 273264894cf8SAl Viro bool got_write, bool need_lookup, 273347237687SAl Viro int *opened) 2734d18e9008SMiklos Szeredi { 2735d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2736d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2737d18e9008SMiklos Szeredi umode_t mode; 2738d18e9008SMiklos Szeredi int error; 2739d18e9008SMiklos Szeredi int acc_mode; 2740d18e9008SMiklos Szeredi int create_error = 0; 2741d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2742116cc022SMiklos Szeredi bool excl; 2743d18e9008SMiklos Szeredi 2744d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2745d18e9008SMiklos Szeredi 2746d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2747d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 27482675a4ebSAl Viro error = -ENOENT; 2749d18e9008SMiklos Szeredi goto out; 2750d18e9008SMiklos Szeredi } 2751d18e9008SMiklos Szeredi 275262b259d8SMiklos Szeredi mode = op->mode; 2753d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2754d18e9008SMiklos Szeredi mode &= ~current_umask(); 2755d18e9008SMiklos Szeredi 2756116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2757116cc022SMiklos Szeredi if (excl) 2758d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2759d18e9008SMiklos Szeredi 2760d18e9008SMiklos Szeredi /* 2761d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2762d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2763d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2764d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2765d18e9008SMiklos Szeredi * 2766d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2767d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2768d18e9008SMiklos Szeredi */ 276964894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 277064894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 277164894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2772d18e9008SMiklos Szeredi /* 2773d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2774d18e9008SMiklos Szeredi * back to lookup + open 2775d18e9008SMiklos Szeredi */ 2776d18e9008SMiklos Szeredi goto no_open; 2777d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2778d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 277964894cf8SAl Viro create_error = -EROFS; 2780d18e9008SMiklos Szeredi goto no_open; 2781d18e9008SMiklos Szeredi } else { 2782d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 278364894cf8SAl Viro create_error = -EROFS; 2784d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2785d18e9008SMiklos Szeredi } 2786d18e9008SMiklos Szeredi } 2787d18e9008SMiklos Szeredi 2788d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 278938227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2790d18e9008SMiklos Szeredi if (error) { 2791d18e9008SMiklos Szeredi create_error = error; 2792d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2793d18e9008SMiklos Szeredi goto no_open; 2794d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2795d18e9008SMiklos Szeredi } 2796d18e9008SMiklos Szeredi } 2797d18e9008SMiklos Szeredi 2798d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2799d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2800d18e9008SMiklos Szeredi 280130d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 280230d90494SAl Viro file->f_path.mnt = nd->path.mnt; 280330d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 280447237687SAl Viro opened); 2805d9585277SAl Viro if (error < 0) { 2806d9585277SAl Viro if (create_error && error == -ENOENT) 2807d9585277SAl Viro error = create_error; 2808d18e9008SMiklos Szeredi goto out; 2809d18e9008SMiklos Szeredi } 2810d18e9008SMiklos Szeredi 2811d9585277SAl Viro if (error) { /* returned 1, that is */ 281230d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 28132675a4ebSAl Viro error = -EIO; 2814d18e9008SMiklos Szeredi goto out; 2815d18e9008SMiklos Szeredi } 281630d90494SAl Viro if (file->f_path.dentry) { 2817d18e9008SMiklos Szeredi dput(dentry); 281830d90494SAl Viro dentry = file->f_path.dentry; 2819d18e9008SMiklos Szeredi } 282003da633aSAl Viro if (*opened & FILE_CREATED) 282103da633aSAl Viro fsnotify_create(dir, dentry); 282203da633aSAl Viro if (!dentry->d_inode) { 282303da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 282403da633aSAl Viro if (create_error) { 282562b2ce96SSage Weil error = create_error; 282662b2ce96SSage Weil goto out; 282762b2ce96SSage Weil } 282803da633aSAl Viro } else { 282903da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 283003da633aSAl Viro error = -EEXIST; 283103da633aSAl Viro goto out; 283203da633aSAl Viro } 283303da633aSAl Viro } 2834d18e9008SMiklos Szeredi goto looked_up; 2835d18e9008SMiklos Szeredi } 2836d18e9008SMiklos Szeredi 2837d18e9008SMiklos Szeredi /* 2838d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2839d18e9008SMiklos Szeredi * here. 2840d18e9008SMiklos Szeredi */ 284103da633aSAl Viro acc_mode = op->acc_mode; 284203da633aSAl Viro if (*opened & FILE_CREATED) { 284303da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 284403da633aSAl Viro fsnotify_create(dir, dentry); 284503da633aSAl Viro acc_mode = MAY_OPEN; 284603da633aSAl Viro } 28472675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 28482675a4ebSAl Viro if (error) 28492675a4ebSAl Viro fput(file); 2850d18e9008SMiklos Szeredi 2851d18e9008SMiklos Szeredi out: 2852d18e9008SMiklos Szeredi dput(dentry); 28532675a4ebSAl Viro return error; 2854d18e9008SMiklos Szeredi 2855d18e9008SMiklos Szeredi no_open: 2856d18e9008SMiklos Szeredi if (need_lookup) { 285772bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2858d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 28592675a4ebSAl Viro return PTR_ERR(dentry); 2860d18e9008SMiklos Szeredi 2861d18e9008SMiklos Szeredi if (create_error) { 2862d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2863d18e9008SMiklos Szeredi 28642675a4ebSAl Viro error = create_error; 2865d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2866d18e9008SMiklos Szeredi if (!dentry->d_inode) 2867d18e9008SMiklos Szeredi goto out; 2868d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2869d18e9008SMiklos Szeredi goto out; 2870d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2871e36cb0b8SDavid Howells d_is_reg(dentry)) { 2872d18e9008SMiklos Szeredi goto out; 2873d18e9008SMiklos Szeredi } 2874d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2875d18e9008SMiklos Szeredi } 2876d18e9008SMiklos Szeredi } 2877d18e9008SMiklos Szeredi looked_up: 2878d18e9008SMiklos Szeredi path->dentry = dentry; 2879d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 28802675a4ebSAl Viro return 1; 2881d18e9008SMiklos Szeredi } 2882d18e9008SMiklos Szeredi 288331e6b01fSNick Piggin /* 28841acf0af9SDavid Howells * Look up and maybe create and open the last component. 2885d58ffd35SMiklos Szeredi * 2886d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2887d58ffd35SMiklos Szeredi * 28881acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 28891acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 28901acf0af9SDavid Howells * 28911acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 28921acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 28931acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 28941acf0af9SDavid Howells * specified then a negative dentry may be returned. 28951acf0af9SDavid Howells * 28961acf0af9SDavid Howells * An error code is returned otherwise. 28971acf0af9SDavid Howells * 28981acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 28991acf0af9SDavid Howells * cleared otherwise prior to returning. 2900d58ffd35SMiklos Szeredi */ 29012675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 290230d90494SAl Viro struct file *file, 2903d58ffd35SMiklos Szeredi const struct open_flags *op, 290464894cf8SAl Viro bool got_write, int *opened) 2905d58ffd35SMiklos Szeredi { 2906d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 290754ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2908d58ffd35SMiklos Szeredi struct dentry *dentry; 2909d58ffd35SMiklos Szeredi int error; 291054ef4872SMiklos Szeredi bool need_lookup; 2911d58ffd35SMiklos Szeredi 291247237687SAl Viro *opened &= ~FILE_CREATED; 2913201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2914d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 29152675a4ebSAl Viro return PTR_ERR(dentry); 2916d58ffd35SMiklos Szeredi 2917d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2918d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2919d18e9008SMiklos Szeredi goto out_no_open; 2920d18e9008SMiklos Szeredi 2921d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 292264894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 292347237687SAl Viro need_lookup, opened); 2924d18e9008SMiklos Szeredi } 2925d18e9008SMiklos Szeredi 292654ef4872SMiklos Szeredi if (need_lookup) { 292754ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 292854ef4872SMiklos Szeredi 292972bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 293054ef4872SMiklos Szeredi if (IS_ERR(dentry)) 29312675a4ebSAl Viro return PTR_ERR(dentry); 293254ef4872SMiklos Szeredi } 293354ef4872SMiklos Szeredi 2934d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2935d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2936d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2937d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2938d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2939d58ffd35SMiklos Szeredi /* 2940d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2941d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2942d58ffd35SMiklos Szeredi * the time when the file is created and when 2943d58ffd35SMiklos Szeredi * a permanent write count is taken through 2944015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 2945d58ffd35SMiklos Szeredi */ 294664894cf8SAl Viro if (!got_write) { 294764894cf8SAl Viro error = -EROFS; 2948d58ffd35SMiklos Szeredi goto out_dput; 294964894cf8SAl Viro } 295047237687SAl Viro *opened |= FILE_CREATED; 2951d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2952d58ffd35SMiklos Szeredi if (error) 2953d58ffd35SMiklos Szeredi goto out_dput; 2954312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 2955312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 2956d58ffd35SMiklos Szeredi if (error) 2957d58ffd35SMiklos Szeredi goto out_dput; 2958d58ffd35SMiklos Szeredi } 2959d18e9008SMiklos Szeredi out_no_open: 2960d58ffd35SMiklos Szeredi path->dentry = dentry; 2961d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 29622675a4ebSAl Viro return 1; 2963d58ffd35SMiklos Szeredi 2964d58ffd35SMiklos Szeredi out_dput: 2965d58ffd35SMiklos Szeredi dput(dentry); 29662675a4ebSAl Viro return error; 2967d58ffd35SMiklos Szeredi } 2968d58ffd35SMiklos Szeredi 2969d58ffd35SMiklos Szeredi /* 2970fe2d35ffSAl Viro * Handle the last step of open() 297131e6b01fSNick Piggin */ 2972896475d5SAl Viro static int do_last(struct nameidata *nd, 297330d90494SAl Viro struct file *file, const struct open_flags *op, 2974669abf4eSJeff Layton int *opened, struct filename *name) 2975fb1cc555SAl Viro { 2976a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2977ca344a89SAl Viro int open_flag = op->open_flag; 297877d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 297964894cf8SAl Viro bool got_write = false; 2980bcda7652SAl Viro int acc_mode = op->acc_mode; 2981a1eb3315SMiklos Szeredi struct inode *inode; 298216b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 2983896475d5SAl Viro struct path path; 298416b1c1cdSMiklos Szeredi bool retried = false; 298516c2cd71SAl Viro int error; 2986fb1cc555SAl Viro 2987c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2988c3e380b0SAl Viro nd->flags |= op->intent; 2989c3e380b0SAl Viro 2990bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 2991fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 299270291aecSAl Viro if (unlikely(error)) { 299370291aecSAl Viro terminate_walk(nd); 29942675a4ebSAl Viro return error; 299570291aecSAl Viro } 2996e83db167SMiklos Szeredi goto finish_open; 29971f36f774SAl Viro } 2998a2c36b45SAl Viro 2999ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3000fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3001fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3002fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3003896475d5SAl Viro error = lookup_fast(nd, &path, &inode); 300471574865SMiklos Szeredi if (likely(!error)) 300571574865SMiklos Szeredi goto finish_lookup; 300671574865SMiklos Szeredi 3007ce57dfc1SAl Viro if (error < 0) 30082675a4ebSAl Viro goto out; 3009a1eb3315SMiklos Szeredi 301037d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 3011b6183df7SMiklos Szeredi } else { 3012fe2d35ffSAl Viro /* create side of things */ 3013a3fbbde7SAl Viro /* 3014b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3015b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3016b6183df7SMiklos Szeredi * about to look up 3017a3fbbde7SAl Viro */ 30189f1fafeeSAl Viro error = complete_walk(nd); 3019e8bb73dfSAl Viro if (error) 30202675a4ebSAl Viro return error; 3021fe2d35ffSAl Viro 302233e2208aSJeff Layton audit_inode(name, dir, LOOKUP_PARENT); 302316c2cd71SAl Viro error = -EISDIR; 30241f36f774SAl Viro /* trailing slashes? */ 302531e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 30262675a4ebSAl Viro goto out; 3027b6183df7SMiklos Szeredi } 30281f36f774SAl Viro 302916b1c1cdSMiklos Szeredi retry_lookup: 303064894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 303164894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 303264894cf8SAl Viro if (!error) 303364894cf8SAl Viro got_write = true; 303464894cf8SAl Viro /* 303564894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 303664894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 303764894cf8SAl Viro * dropping this one anyway. 303864894cf8SAl Viro */ 303964894cf8SAl Viro } 3040a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 3041896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 3042fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 3043fb1cc555SAl Viro 30442675a4ebSAl Viro if (error <= 0) { 30452675a4ebSAl Viro if (error) 3046d58ffd35SMiklos Szeredi goto out; 30476c0d46c4SAl Viro 304847237687SAl Viro if ((*opened & FILE_CREATED) || 3049496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 305077d660a8SMiklos Szeredi will_truncate = false; 3051d18e9008SMiklos Szeredi 3052adb5c247SJeff Layton audit_inode(name, file->f_path.dentry, 0); 3053d18e9008SMiklos Szeredi goto opened; 3054d18e9008SMiklos Szeredi } 3055d18e9008SMiklos Szeredi 305647237687SAl Viro if (*opened & FILE_CREATED) { 30579b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3058ca344a89SAl Viro open_flag &= ~O_TRUNC; 305977d660a8SMiklos Szeredi will_truncate = false; 3060bcda7652SAl Viro acc_mode = MAY_OPEN; 3061896475d5SAl Viro path_to_nameidata(&path, nd); 3062e83db167SMiklos Szeredi goto finish_open_created; 3063fb1cc555SAl Viro } 3064fb1cc555SAl Viro 3065fb1cc555SAl Viro /* 30663134f37eSJeff Layton * create/update audit record if it already exists. 3067fb1cc555SAl Viro */ 3068896475d5SAl Viro if (d_is_positive(path.dentry)) 3069896475d5SAl Viro audit_inode(name, path.dentry, 0); 3070fb1cc555SAl Viro 3071d18e9008SMiklos Szeredi /* 3072d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3073d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3074d18e9008SMiklos Szeredi * necessary...) 3075d18e9008SMiklos Szeredi */ 307664894cf8SAl Viro if (got_write) { 3077d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 307864894cf8SAl Viro got_write = false; 3079d18e9008SMiklos Szeredi } 3080d18e9008SMiklos Szeredi 3081fb1cc555SAl Viro error = -EEXIST; 3082f8310c59SAl Viro if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) 3083fb1cc555SAl Viro goto exit_dput; 3084fb1cc555SAl Viro 3085756daf26SNeilBrown error = follow_managed(&path, nd); 30869875cf80SDavid Howells if (error < 0) 30878402752eSAl Viro goto out; 3088a3fbbde7SAl Viro 3089decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 3090896475d5SAl Viro inode = path.dentry->d_inode; 3091fb1cc555SAl Viro error = -ENOENT; 3092896475d5SAl Viro if (d_is_negative(path.dentry)) { 3093896475d5SAl Viro path_to_nameidata(&path, nd); 30942675a4ebSAl Viro goto out; 309554c33e7fSMiklos Szeredi } 3096766c4cbfSAl Viro finish_lookup: 3097191d7f73SAl Viro if (nd->depth) 3098191d7f73SAl Viro put_link(nd); 3099d63ff28fSAl Viro error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW); 3100d63ff28fSAl Viro if (unlikely(error)) { 3101d63ff28fSAl Viro if (error < 0) 3102d63ff28fSAl Viro goto out; 3103d63ff28fSAl Viro return error; 3104d45ea867SMiklos Szeredi } 3105fb1cc555SAl Viro 3106896475d5SAl Viro if (unlikely(d_is_symlink(path.dentry)) && !(open_flag & O_PATH)) { 3107896475d5SAl Viro path_to_nameidata(&path, nd); 3108a5cfe2d5SAl Viro error = -ELOOP; 3109a5cfe2d5SAl Viro goto out; 3110a5cfe2d5SAl Viro } 3111a5cfe2d5SAl Viro 3112896475d5SAl Viro if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { 3113896475d5SAl Viro path_to_nameidata(&path, nd); 311416b1c1cdSMiklos Szeredi } else { 311516b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 3116896475d5SAl Viro save_parent.mnt = mntget(path.mnt); 3117896475d5SAl Viro nd->path.dentry = path.dentry; 311816b1c1cdSMiklos Szeredi 311916b1c1cdSMiklos Szeredi } 3120decf3400SMiklos Szeredi nd->inode = inode; 3121a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3122bc77daa7SAl Viro finish_open: 3123a3fbbde7SAl Viro error = complete_walk(nd); 312416b1c1cdSMiklos Szeredi if (error) { 312516b1c1cdSMiklos Szeredi path_put(&save_parent); 31262675a4ebSAl Viro return error; 312716b1c1cdSMiklos Szeredi } 3128bc77daa7SAl Viro audit_inode(name, nd->path.dentry, 0); 3129fb1cc555SAl Viro error = -EISDIR; 313044b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 31312675a4ebSAl Viro goto out; 3132af2f5542SMiklos Szeredi error = -ENOTDIR; 313344b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 31342675a4ebSAl Viro goto out; 31354bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 313677d660a8SMiklos Szeredi will_truncate = false; 31376c0d46c4SAl Viro 31380f9d1a10SAl Viro if (will_truncate) { 31390f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 31400f9d1a10SAl Viro if (error) 31412675a4ebSAl Viro goto out; 314264894cf8SAl Viro got_write = true; 31430f9d1a10SAl Viro } 3144e83db167SMiklos Szeredi finish_open_created: 3145bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3146ca344a89SAl Viro if (error) 31472675a4ebSAl Viro goto out; 31484aa7c634SMiklos Szeredi 31494aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 31504aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 31514aa7c634SMiklos Szeredi if (!error) { 31524aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 31534aa7c634SMiklos Szeredi } else { 315430d90494SAl Viro if (error == -EOPENSTALE) 3155f60dc3dbSMiklos Szeredi goto stale_open; 3156015c3bbcSMiklos Szeredi goto out; 3157f60dc3dbSMiklos Szeredi } 3158a8277b9bSMiklos Szeredi opened: 31592675a4ebSAl Viro error = open_check_o_direct(file); 3160015c3bbcSMiklos Szeredi if (error) 3161015c3bbcSMiklos Szeredi goto exit_fput; 31623034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3163aa4caadbSMiklos Szeredi if (error) 3164aa4caadbSMiklos Szeredi goto exit_fput; 3165aa4caadbSMiklos Szeredi 31660f9d1a10SAl Viro if (will_truncate) { 31672675a4ebSAl Viro error = handle_truncate(file); 3168aa4caadbSMiklos Szeredi if (error) 3169aa4caadbSMiklos Szeredi goto exit_fput; 31700f9d1a10SAl Viro } 3171ca344a89SAl Viro out: 317264894cf8SAl Viro if (got_write) 31730f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 317416b1c1cdSMiklos Szeredi path_put(&save_parent); 3175e276ae67SMiklos Szeredi terminate_walk(nd); 31762675a4ebSAl Viro return error; 3177fb1cc555SAl Viro 3178fb1cc555SAl Viro exit_dput: 3179896475d5SAl Viro path_put_conditional(&path, nd); 3180ca344a89SAl Viro goto out; 3181015c3bbcSMiklos Szeredi exit_fput: 31822675a4ebSAl Viro fput(file); 31832675a4ebSAl Viro goto out; 3184015c3bbcSMiklos Szeredi 3185f60dc3dbSMiklos Szeredi stale_open: 3186f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3187f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3188f60dc3dbSMiklos Szeredi goto out; 3189f60dc3dbSMiklos Szeredi 3190f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3191f60dc3dbSMiklos Szeredi path_put(&nd->path); 3192f60dc3dbSMiklos Szeredi nd->path = save_parent; 3193f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3194f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3195f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 319664894cf8SAl Viro if (got_write) { 3197f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 319864894cf8SAl Viro got_write = false; 3199f60dc3dbSMiklos Szeredi } 3200f60dc3dbSMiklos Szeredi retried = true; 3201f60dc3dbSMiklos Szeredi goto retry_lookup; 3202fb1cc555SAl Viro } 3203fb1cc555SAl Viro 320460545d0dSAl Viro static int do_tmpfile(int dfd, struct filename *pathname, 320560545d0dSAl Viro struct nameidata *nd, int flags, 320660545d0dSAl Viro const struct open_flags *op, 320760545d0dSAl Viro struct file *file, int *opened) 320860545d0dSAl Viro { 320960545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 321060545d0dSAl Viro struct dentry *dentry, *child; 321160545d0dSAl Viro struct inode *dir; 32125eb6b495SAl Viro int error = path_lookupat(dfd, pathname, 321360545d0dSAl Viro flags | LOOKUP_DIRECTORY, nd); 321460545d0dSAl Viro if (unlikely(error)) 321560545d0dSAl Viro return error; 321660545d0dSAl Viro error = mnt_want_write(nd->path.mnt); 321760545d0dSAl Viro if (unlikely(error)) 321860545d0dSAl Viro goto out; 321960545d0dSAl Viro /* we want directory to be writable */ 322060545d0dSAl Viro error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); 322160545d0dSAl Viro if (error) 322260545d0dSAl Viro goto out2; 322360545d0dSAl Viro dentry = nd->path.dentry; 322460545d0dSAl Viro dir = dentry->d_inode; 322560545d0dSAl Viro if (!dir->i_op->tmpfile) { 322660545d0dSAl Viro error = -EOPNOTSUPP; 322760545d0dSAl Viro goto out2; 322860545d0dSAl Viro } 322960545d0dSAl Viro child = d_alloc(dentry, &name); 323060545d0dSAl Viro if (unlikely(!child)) { 323160545d0dSAl Viro error = -ENOMEM; 323260545d0dSAl Viro goto out2; 323360545d0dSAl Viro } 323460545d0dSAl Viro nd->flags &= ~LOOKUP_DIRECTORY; 323560545d0dSAl Viro nd->flags |= op->intent; 323660545d0dSAl Viro dput(nd->path.dentry); 323760545d0dSAl Viro nd->path.dentry = child; 323860545d0dSAl Viro error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); 323960545d0dSAl Viro if (error) 324060545d0dSAl Viro goto out2; 324160545d0dSAl Viro audit_inode(pathname, nd->path.dentry, 0); 324269a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 324369a91c23SEric Rannaud error = may_open(&nd->path, MAY_OPEN, op->open_flag); 324460545d0dSAl Viro if (error) 324560545d0dSAl Viro goto out2; 324660545d0dSAl Viro file->f_path.mnt = nd->path.mnt; 324760545d0dSAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 324860545d0dSAl Viro if (error) 324960545d0dSAl Viro goto out2; 325060545d0dSAl Viro error = open_check_o_direct(file); 3251f4e0c30cSAl Viro if (error) { 325260545d0dSAl Viro fput(file); 3253f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3254f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3255f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3256f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3257f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3258f4e0c30cSAl Viro } 325960545d0dSAl Viro out2: 326060545d0dSAl Viro mnt_drop_write(nd->path.mnt); 326160545d0dSAl Viro out: 326260545d0dSAl Viro path_put(&nd->path); 326360545d0dSAl Viro return error; 326460545d0dSAl Viro } 326560545d0dSAl Viro 3266669abf4eSJeff Layton static struct file *path_openat(int dfd, struct filename *pathname, 326773d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 32681da177e4SLinus Torvalds { 326930d90494SAl Viro struct file *file; 327047237687SAl Viro int opened = 0; 327113aab428SAl Viro int error; 327231e6b01fSNick Piggin 327330d90494SAl Viro file = get_empty_filp(); 32741afc99beSAl Viro if (IS_ERR(file)) 32751afc99beSAl Viro return file; 327631e6b01fSNick Piggin 327730d90494SAl Viro file->f_flags = op->open_flag; 327831e6b01fSNick Piggin 3279bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 328060545d0dSAl Viro error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); 3281f15133dfSAl Viro goto out2; 328260545d0dSAl Viro } 328360545d0dSAl Viro 32846e8a1f87SAl Viro error = path_init(dfd, pathname, flags, nd); 328531e6b01fSNick Piggin if (unlikely(error)) 32862675a4ebSAl Viro goto out; 32871da177e4SLinus Torvalds 3288191d7f73SAl Viro while ((error = do_last(nd, file, op, &opened, pathname)) > 0) { 328973d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 32901d8e03d3SAl Viro error = trailing_symlink(nd); 3291c3e380b0SAl Viro if (unlikely(error)) 32922675a4ebSAl Viro break; 3293806b681cSAl Viro } 329410fa8e62SAl Viro out: 3295893b7775SAl Viro path_cleanup(nd); 3296f15133dfSAl Viro out2: 32972675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 32982675a4ebSAl Viro BUG_ON(!error); 329930d90494SAl Viro put_filp(file); 3300015c3bbcSMiklos Szeredi } 33012675a4ebSAl Viro if (unlikely(error)) { 33022675a4ebSAl Viro if (error == -EOPENSTALE) { 33032675a4ebSAl Viro if (flags & LOOKUP_RCU) 33042675a4ebSAl Viro error = -ECHILD; 33052675a4ebSAl Viro else 33062675a4ebSAl Viro error = -ESTALE; 33072675a4ebSAl Viro } 33082675a4ebSAl Viro file = ERR_PTR(error); 33092675a4ebSAl Viro } 33102675a4ebSAl Viro return file; 3311de459215SKirill Korotaev } 33121da177e4SLinus Torvalds 3313669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3314f9652e10SAl Viro const struct open_flags *op) 331513aab428SAl Viro { 3316756daf26SNeilBrown struct nameidata nd, *saved_nd = set_nameidata(&nd); 3317f9652e10SAl Viro int flags = op->lookup_flags; 331813aab428SAl Viro struct file *filp; 331913aab428SAl Viro 332073d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 332113aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 332273d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 332313aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 332473d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 3325756daf26SNeilBrown restore_nameidata(saved_nd); 332613aab428SAl Viro return filp; 332713aab428SAl Viro } 332813aab428SAl Viro 332973d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3330f9652e10SAl Viro const char *name, const struct open_flags *op) 333173d049a4SAl Viro { 3332756daf26SNeilBrown struct nameidata nd, *saved_nd; 333373d049a4SAl Viro struct file *file; 333451689104SPaul Moore struct filename *filename; 3335f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 333673d049a4SAl Viro 333773d049a4SAl Viro nd.root.mnt = mnt; 333873d049a4SAl Viro nd.root.dentry = dentry; 333973d049a4SAl Viro 3340b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 334173d049a4SAl Viro return ERR_PTR(-ELOOP); 334273d049a4SAl Viro 334351689104SPaul Moore filename = getname_kernel(name); 334451689104SPaul Moore if (unlikely(IS_ERR(filename))) 334551689104SPaul Moore return ERR_CAST(filename); 334651689104SPaul Moore 3347756daf26SNeilBrown saved_nd = set_nameidata(&nd); 334851689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_RCU); 334973d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 335051689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags); 335173d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 335251689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_REVAL); 3353756daf26SNeilBrown restore_nameidata(saved_nd); 335451689104SPaul Moore putname(filename); 335573d049a4SAl Viro return file; 335673d049a4SAl Viro } 335773d049a4SAl Viro 3358fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 33591ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 33601da177e4SLinus Torvalds { 3361c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3362ed75e95dSAl Viro struct nameidata nd; 3363c30dabfeSJan Kara int err2; 33641ac12b4bSJeff Layton int error; 33651ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 33661ac12b4bSJeff Layton 33671ac12b4bSJeff Layton /* 33681ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 33691ac12b4bSJeff Layton * other flags passed in are ignored! 33701ac12b4bSJeff Layton */ 33711ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 33721ac12b4bSJeff Layton 33738bcb77faSAl Viro error = filename_parentat(dfd, name, lookup_flags, &nd); 3374ed75e95dSAl Viro if (error) 3375ed75e95dSAl Viro return ERR_PTR(error); 33761da177e4SLinus Torvalds 3377c663e5d8SChristoph Hellwig /* 3378c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3379c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3380c663e5d8SChristoph Hellwig */ 3381ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 3382ed75e95dSAl Viro goto out; 3383ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 3384ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 3385c663e5d8SChristoph Hellwig 3386c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3387c30dabfeSJan Kara err2 = mnt_want_write(nd.path.mnt); 3388c663e5d8SChristoph Hellwig /* 3389c663e5d8SChristoph Hellwig * Do the final lookup. 3390c663e5d8SChristoph Hellwig */ 3391ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 33926a9f40d6SAl Viro dentry = __lookup_hash(&nd.last, nd.path.dentry, nd.flags); 33931da177e4SLinus Torvalds if (IS_ERR(dentry)) 3394a8104a9fSAl Viro goto unlock; 3395c663e5d8SChristoph Hellwig 3396a8104a9fSAl Viro error = -EEXIST; 3397b18825a7SDavid Howells if (d_is_positive(dentry)) 3398a8104a9fSAl Viro goto fail; 3399b18825a7SDavid Howells 3400c663e5d8SChristoph Hellwig /* 3401c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3402c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3403c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3404c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3405c663e5d8SChristoph Hellwig */ 3406ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 3407a8104a9fSAl Viro error = -ENOENT; 3408ed75e95dSAl Viro goto fail; 3409e9baf6e5SAl Viro } 3410c30dabfeSJan Kara if (unlikely(err2)) { 3411c30dabfeSJan Kara error = err2; 3412a8104a9fSAl Viro goto fail; 3413c30dabfeSJan Kara } 3414ed75e95dSAl Viro *path = nd.path; 3415e9baf6e5SAl Viro return dentry; 34161da177e4SLinus Torvalds fail: 3417a8104a9fSAl Viro dput(dentry); 3418a8104a9fSAl Viro dentry = ERR_PTR(error); 3419a8104a9fSAl Viro unlock: 3420dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3421c30dabfeSJan Kara if (!err2) 3422c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 3423ed75e95dSAl Viro out: 3424dae6ad8fSAl Viro path_put(&nd.path); 3425ed75e95dSAl Viro return dentry; 3426dae6ad8fSAl Viro } 3427fa14a0b8SAl Viro 3428fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3429fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3430fa14a0b8SAl Viro { 343151689104SPaul Moore struct filename *filename = getname_kernel(pathname); 343251689104SPaul Moore struct dentry *res; 343351689104SPaul Moore 343451689104SPaul Moore if (IS_ERR(filename)) 343551689104SPaul Moore return ERR_CAST(filename); 343651689104SPaul Moore res = filename_create(dfd, filename, path, lookup_flags); 343751689104SPaul Moore putname(filename); 343851689104SPaul Moore return res; 3439fa14a0b8SAl Viro } 3440dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3441dae6ad8fSAl Viro 3442921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3443921a1650SAl Viro { 3444921a1650SAl Viro dput(dentry); 3445921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3446a8104a9fSAl Viro mnt_drop_write(path->mnt); 3447921a1650SAl Viro path_put(path); 3448921a1650SAl Viro } 3449921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3450921a1650SAl Viro 34511ac12b4bSJeff Layton struct dentry *user_path_create(int dfd, const char __user *pathname, 34521ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3453dae6ad8fSAl Viro { 345491a27b2aSJeff Layton struct filename *tmp = getname(pathname); 3455dae6ad8fSAl Viro struct dentry *res; 3456dae6ad8fSAl Viro if (IS_ERR(tmp)) 3457dae6ad8fSAl Viro return ERR_CAST(tmp); 3458fa14a0b8SAl Viro res = filename_create(dfd, tmp, path, lookup_flags); 3459dae6ad8fSAl Viro putname(tmp); 3460dae6ad8fSAl Viro return res; 3461dae6ad8fSAl Viro } 3462dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3463dae6ad8fSAl Viro 34641a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 34651da177e4SLinus Torvalds { 3466a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 34671da177e4SLinus Torvalds 34681da177e4SLinus Torvalds if (error) 34691da177e4SLinus Torvalds return error; 34701da177e4SLinus Torvalds 3471975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 34721da177e4SLinus Torvalds return -EPERM; 34731da177e4SLinus Torvalds 3474acfa4380SAl Viro if (!dir->i_op->mknod) 34751da177e4SLinus Torvalds return -EPERM; 34761da177e4SLinus Torvalds 347708ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 347808ce5f16SSerge E. Hallyn if (error) 347908ce5f16SSerge E. Hallyn return error; 348008ce5f16SSerge E. Hallyn 34811da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 34821da177e4SLinus Torvalds if (error) 34831da177e4SLinus Torvalds return error; 34841da177e4SLinus Torvalds 34851da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3486a74574aaSStephen Smalley if (!error) 3487f38aa942SAmy Griffis fsnotify_create(dir, dentry); 34881da177e4SLinus Torvalds return error; 34891da177e4SLinus Torvalds } 34904d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 34911da177e4SLinus Torvalds 3492f69aac00SAl Viro static int may_mknod(umode_t mode) 3493463c3197SDave Hansen { 3494463c3197SDave Hansen switch (mode & S_IFMT) { 3495463c3197SDave Hansen case S_IFREG: 3496463c3197SDave Hansen case S_IFCHR: 3497463c3197SDave Hansen case S_IFBLK: 3498463c3197SDave Hansen case S_IFIFO: 3499463c3197SDave Hansen case S_IFSOCK: 3500463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3501463c3197SDave Hansen return 0; 3502463c3197SDave Hansen case S_IFDIR: 3503463c3197SDave Hansen return -EPERM; 3504463c3197SDave Hansen default: 3505463c3197SDave Hansen return -EINVAL; 3506463c3197SDave Hansen } 3507463c3197SDave Hansen } 3508463c3197SDave Hansen 35098208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 35102e4d0924SHeiko Carstens unsigned, dev) 35111da177e4SLinus Torvalds { 35121da177e4SLinus Torvalds struct dentry *dentry; 3513dae6ad8fSAl Viro struct path path; 3514dae6ad8fSAl Viro int error; 3515972567f1SJeff Layton unsigned int lookup_flags = 0; 35161da177e4SLinus Torvalds 35178e4bfca1SAl Viro error = may_mknod(mode); 35188e4bfca1SAl Viro if (error) 35198e4bfca1SAl Viro return error; 3520972567f1SJeff Layton retry: 3521972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3522dae6ad8fSAl Viro if (IS_ERR(dentry)) 3523dae6ad8fSAl Viro return PTR_ERR(dentry); 35242ad94ae6SAl Viro 3525dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3526ce3b0f8dSAl Viro mode &= ~current_umask(); 3527dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3528be6d3e56SKentaro Takeda if (error) 3529a8104a9fSAl Viro goto out; 35301da177e4SLinus Torvalds switch (mode & S_IFMT) { 35311da177e4SLinus Torvalds case 0: case S_IFREG: 3532312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 35331da177e4SLinus Torvalds break; 35341da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3535dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 35361da177e4SLinus Torvalds new_decode_dev(dev)); 35371da177e4SLinus Torvalds break; 35381da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3539dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 35401da177e4SLinus Torvalds break; 35411da177e4SLinus Torvalds } 3542a8104a9fSAl Viro out: 3543921a1650SAl Viro done_path_create(&path, dentry); 3544972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3545972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3546972567f1SJeff Layton goto retry; 3547972567f1SJeff Layton } 35481da177e4SLinus Torvalds return error; 35491da177e4SLinus Torvalds } 35501da177e4SLinus Torvalds 35518208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 35525590ff0dSUlrich Drepper { 35535590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 35545590ff0dSUlrich Drepper } 35555590ff0dSUlrich Drepper 355618bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 35571da177e4SLinus Torvalds { 3558a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35598de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 35601da177e4SLinus Torvalds 35611da177e4SLinus Torvalds if (error) 35621da177e4SLinus Torvalds return error; 35631da177e4SLinus Torvalds 3564acfa4380SAl Viro if (!dir->i_op->mkdir) 35651da177e4SLinus Torvalds return -EPERM; 35661da177e4SLinus Torvalds 35671da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 35681da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 35691da177e4SLinus Torvalds if (error) 35701da177e4SLinus Torvalds return error; 35711da177e4SLinus Torvalds 35728de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 35738de52778SAl Viro return -EMLINK; 35748de52778SAl Viro 35751da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3576a74574aaSStephen Smalley if (!error) 3577f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 35781da177e4SLinus Torvalds return error; 35791da177e4SLinus Torvalds } 35804d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 35811da177e4SLinus Torvalds 3582a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 35831da177e4SLinus Torvalds { 35846902d925SDave Hansen struct dentry *dentry; 3585dae6ad8fSAl Viro struct path path; 3586dae6ad8fSAl Viro int error; 3587b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 35881da177e4SLinus Torvalds 3589b76d8b82SJeff Layton retry: 3590b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 35916902d925SDave Hansen if (IS_ERR(dentry)) 3592dae6ad8fSAl Viro return PTR_ERR(dentry); 35936902d925SDave Hansen 3594dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3595ce3b0f8dSAl Viro mode &= ~current_umask(); 3596dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3597a8104a9fSAl Viro if (!error) 3598dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3599921a1650SAl Viro done_path_create(&path, dentry); 3600b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3601b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3602b76d8b82SJeff Layton goto retry; 3603b76d8b82SJeff Layton } 36041da177e4SLinus Torvalds return error; 36051da177e4SLinus Torvalds } 36061da177e4SLinus Torvalds 3607a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 36085590ff0dSUlrich Drepper { 36095590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 36105590ff0dSUlrich Drepper } 36115590ff0dSUlrich Drepper 36121da177e4SLinus Torvalds /* 3613a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3614c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3615a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3616a71905f0SSage Weil * then we drop the dentry now. 36171da177e4SLinus Torvalds * 36181da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 36191da177e4SLinus Torvalds * do a 36201da177e4SLinus Torvalds * 36211da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 36221da177e4SLinus Torvalds * return -EBUSY; 36231da177e4SLinus Torvalds * 36241da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 36251da177e4SLinus Torvalds * that is still in use by something else.. 36261da177e4SLinus Torvalds */ 36271da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 36281da177e4SLinus Torvalds { 36291da177e4SLinus Torvalds shrink_dcache_parent(dentry); 36301da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 363198474236SWaiman Long if (dentry->d_lockref.count == 1) 36321da177e4SLinus Torvalds __d_drop(dentry); 36331da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 36341da177e4SLinus Torvalds } 36354d359507SAl Viro EXPORT_SYMBOL(dentry_unhash); 36361da177e4SLinus Torvalds 36371da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 36381da177e4SLinus Torvalds { 36391da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 36401da177e4SLinus Torvalds 36411da177e4SLinus Torvalds if (error) 36421da177e4SLinus Torvalds return error; 36431da177e4SLinus Torvalds 3644acfa4380SAl Viro if (!dir->i_op->rmdir) 36451da177e4SLinus Torvalds return -EPERM; 36461da177e4SLinus Torvalds 36471d2ef590SAl Viro dget(dentry); 36481b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3649912dbc15SSage Weil 36501da177e4SLinus Torvalds error = -EBUSY; 36517af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3652912dbc15SSage Weil goto out; 3653912dbc15SSage Weil 36541da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3655912dbc15SSage Weil if (error) 3656912dbc15SSage Weil goto out; 3657912dbc15SSage Weil 36583cebde24SSage Weil shrink_dcache_parent(dentry); 36591da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3660912dbc15SSage Weil if (error) 3661912dbc15SSage Weil goto out; 3662912dbc15SSage Weil 36631da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3664d83c49f3SAl Viro dont_mount(dentry); 36658ed936b5SEric W. Biederman detach_mounts(dentry); 36661da177e4SLinus Torvalds 3667912dbc15SSage Weil out: 3668912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 36691d2ef590SAl Viro dput(dentry); 3670912dbc15SSage Weil if (!error) 3671912dbc15SSage Weil d_delete(dentry); 36721da177e4SLinus Torvalds return error; 36731da177e4SLinus Torvalds } 36744d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 36751da177e4SLinus Torvalds 36765590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 36771da177e4SLinus Torvalds { 36781da177e4SLinus Torvalds int error = 0; 367991a27b2aSJeff Layton struct filename *name; 36801da177e4SLinus Torvalds struct dentry *dentry; 3681f5beed75SAl Viro struct path path; 3682f5beed75SAl Viro struct qstr last; 3683f5beed75SAl Viro int type; 3684c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3685c6ee9206SJeff Layton retry: 3686f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3687f5beed75SAl Viro &path, &last, &type, lookup_flags); 368891a27b2aSJeff Layton if (IS_ERR(name)) 368991a27b2aSJeff Layton return PTR_ERR(name); 36901da177e4SLinus Torvalds 3691f5beed75SAl Viro switch (type) { 36921da177e4SLinus Torvalds case LAST_DOTDOT: 36931da177e4SLinus Torvalds error = -ENOTEMPTY; 36941da177e4SLinus Torvalds goto exit1; 36951da177e4SLinus Torvalds case LAST_DOT: 36961da177e4SLinus Torvalds error = -EINVAL; 36971da177e4SLinus Torvalds goto exit1; 36981da177e4SLinus Torvalds case LAST_ROOT: 36991da177e4SLinus Torvalds error = -EBUSY; 37001da177e4SLinus Torvalds goto exit1; 37011da177e4SLinus Torvalds } 37020612d9fbSOGAWA Hirofumi 3703f5beed75SAl Viro error = mnt_want_write(path.mnt); 3704c30dabfeSJan Kara if (error) 3705c30dabfeSJan Kara goto exit1; 37060612d9fbSOGAWA Hirofumi 3707f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3708f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 37091da177e4SLinus Torvalds error = PTR_ERR(dentry); 37106902d925SDave Hansen if (IS_ERR(dentry)) 37116902d925SDave Hansen goto exit2; 3712e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3713e6bc45d6STheodore Ts'o error = -ENOENT; 3714e6bc45d6STheodore Ts'o goto exit3; 3715e6bc45d6STheodore Ts'o } 3716f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3717be6d3e56SKentaro Takeda if (error) 3718c30dabfeSJan Kara goto exit3; 3719f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 37200622753bSDave Hansen exit3: 37211da177e4SLinus Torvalds dput(dentry); 37226902d925SDave Hansen exit2: 3723f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 3724f5beed75SAl Viro mnt_drop_write(path.mnt); 37251da177e4SLinus Torvalds exit1: 3726f5beed75SAl Viro path_put(&path); 37271da177e4SLinus Torvalds putname(name); 3728c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3729c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3730c6ee9206SJeff Layton goto retry; 3731c6ee9206SJeff Layton } 37321da177e4SLinus Torvalds return error; 37331da177e4SLinus Torvalds } 37341da177e4SLinus Torvalds 37353cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 37365590ff0dSUlrich Drepper { 37375590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 37385590ff0dSUlrich Drepper } 37395590ff0dSUlrich Drepper 3740b21996e3SJ. Bruce Fields /** 3741b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3742b21996e3SJ. Bruce Fields * @dir: parent directory 3743b21996e3SJ. Bruce Fields * @dentry: victim 3744b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3745b21996e3SJ. Bruce Fields * 3746b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3747b21996e3SJ. Bruce Fields * 3748b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3749b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3750b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3751b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3752b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3753b21996e3SJ. Bruce Fields * 3754b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3755b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3756b21996e3SJ. Bruce Fields * to be NFS exported. 3757b21996e3SJ. Bruce Fields */ 3758b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 37591da177e4SLinus Torvalds { 37609accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 37611da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 37621da177e4SLinus Torvalds 37631da177e4SLinus Torvalds if (error) 37641da177e4SLinus Torvalds return error; 37651da177e4SLinus Torvalds 3766acfa4380SAl Viro if (!dir->i_op->unlink) 37671da177e4SLinus Torvalds return -EPERM; 37681da177e4SLinus Torvalds 37699accbb97SJ. Bruce Fields mutex_lock(&target->i_mutex); 37708ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 37711da177e4SLinus Torvalds error = -EBUSY; 37721da177e4SLinus Torvalds else { 37731da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3774bec1052eSAl Viro if (!error) { 37755a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 37765a14696cSJ. Bruce Fields if (error) 3777b21996e3SJ. Bruce Fields goto out; 37781da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 37798ed936b5SEric W. Biederman if (!error) { 3780d83c49f3SAl Viro dont_mount(dentry); 37818ed936b5SEric W. Biederman detach_mounts(dentry); 37828ed936b5SEric W. Biederman } 3783bec1052eSAl Viro } 37841da177e4SLinus Torvalds } 3785b21996e3SJ. Bruce Fields out: 37869accbb97SJ. Bruce Fields mutex_unlock(&target->i_mutex); 37871da177e4SLinus Torvalds 37881da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 37891da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 37909accbb97SJ. Bruce Fields fsnotify_link_count(target); 37911da177e4SLinus Torvalds d_delete(dentry); 37921da177e4SLinus Torvalds } 37930eeca283SRobert Love 37941da177e4SLinus Torvalds return error; 37951da177e4SLinus Torvalds } 37964d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 37971da177e4SLinus Torvalds 37981da177e4SLinus Torvalds /* 37991da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 38001b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 38011da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 38021da177e4SLinus Torvalds * while waiting on the I/O. 38031da177e4SLinus Torvalds */ 38045590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 38051da177e4SLinus Torvalds { 38062ad94ae6SAl Viro int error; 380791a27b2aSJeff Layton struct filename *name; 38081da177e4SLinus Torvalds struct dentry *dentry; 3809f5beed75SAl Viro struct path path; 3810f5beed75SAl Viro struct qstr last; 3811f5beed75SAl Viro int type; 38121da177e4SLinus Torvalds struct inode *inode = NULL; 3813b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 38145d18f813SJeff Layton unsigned int lookup_flags = 0; 38155d18f813SJeff Layton retry: 3816f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3817f5beed75SAl Viro &path, &last, &type, lookup_flags); 381891a27b2aSJeff Layton if (IS_ERR(name)) 381991a27b2aSJeff Layton return PTR_ERR(name); 38202ad94ae6SAl Viro 38211da177e4SLinus Torvalds error = -EISDIR; 3822f5beed75SAl Viro if (type != LAST_NORM) 38231da177e4SLinus Torvalds goto exit1; 38240612d9fbSOGAWA Hirofumi 3825f5beed75SAl Viro error = mnt_want_write(path.mnt); 3826c30dabfeSJan Kara if (error) 3827c30dabfeSJan Kara goto exit1; 3828b21996e3SJ. Bruce Fields retry_deleg: 3829f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3830f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38311da177e4SLinus Torvalds error = PTR_ERR(dentry); 38321da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 38331da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3834f5beed75SAl Viro if (last.name[last.len]) 383550338b88STörök Edwin goto slashes; 38361da177e4SLinus Torvalds inode = dentry->d_inode; 3837b18825a7SDavid Howells if (d_is_negative(dentry)) 3838e6bc45d6STheodore Ts'o goto slashes; 38397de9c6eeSAl Viro ihold(inode); 3840f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3841be6d3e56SKentaro Takeda if (error) 3842c30dabfeSJan Kara goto exit2; 3843f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 38441da177e4SLinus Torvalds exit2: 38451da177e4SLinus Torvalds dput(dentry); 38461da177e4SLinus Torvalds } 3847f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 38481da177e4SLinus Torvalds if (inode) 38491da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3850b21996e3SJ. Bruce Fields inode = NULL; 3851b21996e3SJ. Bruce Fields if (delegated_inode) { 38525a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3853b21996e3SJ. Bruce Fields if (!error) 3854b21996e3SJ. Bruce Fields goto retry_deleg; 3855b21996e3SJ. Bruce Fields } 3856f5beed75SAl Viro mnt_drop_write(path.mnt); 38571da177e4SLinus Torvalds exit1: 3858f5beed75SAl Viro path_put(&path); 38591da177e4SLinus Torvalds putname(name); 38605d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 38615d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 38625d18f813SJeff Layton inode = NULL; 38635d18f813SJeff Layton goto retry; 38645d18f813SJeff Layton } 38651da177e4SLinus Torvalds return error; 38661da177e4SLinus Torvalds 38671da177e4SLinus Torvalds slashes: 3868b18825a7SDavid Howells if (d_is_negative(dentry)) 3869b18825a7SDavid Howells error = -ENOENT; 387044b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3871b18825a7SDavid Howells error = -EISDIR; 3872b18825a7SDavid Howells else 3873b18825a7SDavid Howells error = -ENOTDIR; 38741da177e4SLinus Torvalds goto exit2; 38751da177e4SLinus Torvalds } 38761da177e4SLinus Torvalds 38772e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 38785590ff0dSUlrich Drepper { 38795590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 38805590ff0dSUlrich Drepper return -EINVAL; 38815590ff0dSUlrich Drepper 38825590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 38835590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 38845590ff0dSUlrich Drepper 38855590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 38865590ff0dSUlrich Drepper } 38875590ff0dSUlrich Drepper 38883480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 38895590ff0dSUlrich Drepper { 38905590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 38915590ff0dSUlrich Drepper } 38925590ff0dSUlrich Drepper 3893db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 38941da177e4SLinus Torvalds { 3895a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 38961da177e4SLinus Torvalds 38971da177e4SLinus Torvalds if (error) 38981da177e4SLinus Torvalds return error; 38991da177e4SLinus Torvalds 3900acfa4380SAl Viro if (!dir->i_op->symlink) 39011da177e4SLinus Torvalds return -EPERM; 39021da177e4SLinus Torvalds 39031da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 39041da177e4SLinus Torvalds if (error) 39051da177e4SLinus Torvalds return error; 39061da177e4SLinus Torvalds 39071da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3908a74574aaSStephen Smalley if (!error) 3909f38aa942SAmy Griffis fsnotify_create(dir, dentry); 39101da177e4SLinus Torvalds return error; 39111da177e4SLinus Torvalds } 39124d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 39131da177e4SLinus Torvalds 39142e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 39152e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 39161da177e4SLinus Torvalds { 39172ad94ae6SAl Viro int error; 391891a27b2aSJeff Layton struct filename *from; 39196902d925SDave Hansen struct dentry *dentry; 3920dae6ad8fSAl Viro struct path path; 3921f46d3567SJeff Layton unsigned int lookup_flags = 0; 39221da177e4SLinus Torvalds 39231da177e4SLinus Torvalds from = getname(oldname); 39241da177e4SLinus Torvalds if (IS_ERR(from)) 39251da177e4SLinus Torvalds return PTR_ERR(from); 3926f46d3567SJeff Layton retry: 3927f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 39281da177e4SLinus Torvalds error = PTR_ERR(dentry); 39296902d925SDave Hansen if (IS_ERR(dentry)) 3930dae6ad8fSAl Viro goto out_putname; 39316902d925SDave Hansen 393291a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3933a8104a9fSAl Viro if (!error) 393491a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3935921a1650SAl Viro done_path_create(&path, dentry); 3936f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 3937f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 3938f46d3567SJeff Layton goto retry; 3939f46d3567SJeff Layton } 39406902d925SDave Hansen out_putname: 39411da177e4SLinus Torvalds putname(from); 39421da177e4SLinus Torvalds return error; 39431da177e4SLinus Torvalds } 39441da177e4SLinus Torvalds 39453480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 39465590ff0dSUlrich Drepper { 39475590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 39485590ff0dSUlrich Drepper } 39495590ff0dSUlrich Drepper 3950146a8595SJ. Bruce Fields /** 3951146a8595SJ. Bruce Fields * vfs_link - create a new link 3952146a8595SJ. Bruce Fields * @old_dentry: object to be linked 3953146a8595SJ. Bruce Fields * @dir: new parent 3954146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 3955146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 3956146a8595SJ. Bruce Fields * 3957146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 3958146a8595SJ. Bruce Fields * 3959146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 3960146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 3961146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 3962146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 3963146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 3964146a8595SJ. Bruce Fields * 3965146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3966146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3967146a8595SJ. Bruce Fields * to be NFS exported. 3968146a8595SJ. Bruce Fields */ 3969146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 39701da177e4SLinus Torvalds { 39711da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 39728de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 39731da177e4SLinus Torvalds int error; 39741da177e4SLinus Torvalds 39751da177e4SLinus Torvalds if (!inode) 39761da177e4SLinus Torvalds return -ENOENT; 39771da177e4SLinus Torvalds 3978a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 39791da177e4SLinus Torvalds if (error) 39801da177e4SLinus Torvalds return error; 39811da177e4SLinus Torvalds 39821da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 39831da177e4SLinus Torvalds return -EXDEV; 39841da177e4SLinus Torvalds 39851da177e4SLinus Torvalds /* 39861da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 39871da177e4SLinus Torvalds */ 39881da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 39891da177e4SLinus Torvalds return -EPERM; 3990acfa4380SAl Viro if (!dir->i_op->link) 39911da177e4SLinus Torvalds return -EPERM; 39927e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 39931da177e4SLinus Torvalds return -EPERM; 39941da177e4SLinus Torvalds 39951da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 39961da177e4SLinus Torvalds if (error) 39971da177e4SLinus Torvalds return error; 39981da177e4SLinus Torvalds 39997e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 4000aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4001f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4002aae8a97dSAneesh Kumar K.V error = -ENOENT; 40038de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 40048de52778SAl Viro error = -EMLINK; 4005146a8595SJ. Bruce Fields else { 4006146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4007146a8595SJ. Bruce Fields if (!error) 40081da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4009146a8595SJ. Bruce Fields } 4010f4e0c30cSAl Viro 4011f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4012f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4013f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4014f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4015f4e0c30cSAl Viro } 40167e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 4017e31e14ecSStephen Smalley if (!error) 40187e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 40191da177e4SLinus Torvalds return error; 40201da177e4SLinus Torvalds } 40214d359507SAl Viro EXPORT_SYMBOL(vfs_link); 40221da177e4SLinus Torvalds 40231da177e4SLinus Torvalds /* 40241da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 40251da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 40261da177e4SLinus Torvalds * newname. --KAB 40271da177e4SLinus Torvalds * 40281da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 40291da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 40301da177e4SLinus Torvalds * and other special files. --ADM 40311da177e4SLinus Torvalds */ 40322e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 40332e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 40341da177e4SLinus Torvalds { 40351da177e4SLinus Torvalds struct dentry *new_dentry; 4036dae6ad8fSAl Viro struct path old_path, new_path; 4037146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 403811a7b371SAneesh Kumar K.V int how = 0; 40391da177e4SLinus Torvalds int error; 40401da177e4SLinus Torvalds 404111a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4042c04030e1SUlrich Drepper return -EINVAL; 404311a7b371SAneesh Kumar K.V /* 4044f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4045f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4046f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 404711a7b371SAneesh Kumar K.V */ 4048f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4049f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4050f0cc6ffbSLinus Torvalds return -ENOENT; 405111a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4052f0cc6ffbSLinus Torvalds } 4053c04030e1SUlrich Drepper 405411a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 405511a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4056442e31caSJeff Layton retry: 405711a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 40581da177e4SLinus Torvalds if (error) 40592ad94ae6SAl Viro return error; 40602ad94ae6SAl Viro 4061442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4062442e31caSJeff Layton (how & LOOKUP_REVAL)); 40631da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 40646902d925SDave Hansen if (IS_ERR(new_dentry)) 4065dae6ad8fSAl Viro goto out; 4066dae6ad8fSAl Viro 4067dae6ad8fSAl Viro error = -EXDEV; 4068dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4069dae6ad8fSAl Viro goto out_dput; 4070800179c9SKees Cook error = may_linkat(&old_path); 4071800179c9SKees Cook if (unlikely(error)) 4072800179c9SKees Cook goto out_dput; 4073dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4074be6d3e56SKentaro Takeda if (error) 4075a8104a9fSAl Viro goto out_dput; 4076146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 407775c3f29dSDave Hansen out_dput: 4078921a1650SAl Viro done_path_create(&new_path, new_dentry); 4079146a8595SJ. Bruce Fields if (delegated_inode) { 4080146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4081d22e6338SOleg Drokin if (!error) { 4082d22e6338SOleg Drokin path_put(&old_path); 4083146a8595SJ. Bruce Fields goto retry; 4084146a8595SJ. Bruce Fields } 4085d22e6338SOleg Drokin } 4086442e31caSJeff Layton if (retry_estale(error, how)) { 4087d22e6338SOleg Drokin path_put(&old_path); 4088442e31caSJeff Layton how |= LOOKUP_REVAL; 4089442e31caSJeff Layton goto retry; 4090442e31caSJeff Layton } 40911da177e4SLinus Torvalds out: 40922d8f3038SAl Viro path_put(&old_path); 40931da177e4SLinus Torvalds 40941da177e4SLinus Torvalds return error; 40951da177e4SLinus Torvalds } 40961da177e4SLinus Torvalds 40973480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 40985590ff0dSUlrich Drepper { 4099c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 41005590ff0dSUlrich Drepper } 41015590ff0dSUlrich Drepper 4102bc27027aSMiklos Szeredi /** 4103bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4104bc27027aSMiklos Szeredi * @old_dir: parent of source 4105bc27027aSMiklos Szeredi * @old_dentry: source 4106bc27027aSMiklos Szeredi * @new_dir: parent of destination 4107bc27027aSMiklos Szeredi * @new_dentry: destination 4108bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4109520c8b16SMiklos Szeredi * @flags: rename flags 4110bc27027aSMiklos Szeredi * 4111bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4112bc27027aSMiklos Szeredi * 4113bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4114bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4115bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4116bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4117bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4118bc27027aSMiklos Szeredi * so. 4119bc27027aSMiklos Szeredi * 4120bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4121bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4122bc27027aSMiklos Szeredi * to be NFS exported. 4123bc27027aSMiklos Szeredi * 41241da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 41251da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 41261da177e4SLinus Torvalds * Problems: 4127d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 41281da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 41291da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4130a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 41311da177e4SLinus Torvalds * story. 41326cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 41336cedba89SJ. Bruce Fields * and source (if it is not a directory). 41341b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 41351da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 41361da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4137a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 41381da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 41391da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 41401da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4141a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 41421da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 41431da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 41441da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4145e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 41461b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 41471da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4148c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 41491da177e4SLinus Torvalds * locking]. 41501da177e4SLinus Torvalds */ 41511da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 41528e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4153520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 41541da177e4SLinus Torvalds { 41551da177e4SLinus Torvalds int error; 4156bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 415759b0df21SEric Paris const unsigned char *old_name; 4158bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4159bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4160da1ce067SMiklos Szeredi bool new_is_dir = false; 4161da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 41621da177e4SLinus Torvalds 4163bc27027aSMiklos Szeredi if (source == target) 41641da177e4SLinus Torvalds return 0; 41651da177e4SLinus Torvalds 41661da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 41671da177e4SLinus Torvalds if (error) 41681da177e4SLinus Torvalds return error; 41691da177e4SLinus Torvalds 4170da1ce067SMiklos Szeredi if (!target) { 4171a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4172da1ce067SMiklos Szeredi } else { 4173da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4174da1ce067SMiklos Szeredi 4175da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 41761da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4177da1ce067SMiklos Szeredi else 4178da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4179da1ce067SMiklos Szeredi } 41801da177e4SLinus Torvalds if (error) 41811da177e4SLinus Torvalds return error; 41821da177e4SLinus Torvalds 41837177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 41841da177e4SLinus Torvalds return -EPERM; 41851da177e4SLinus Torvalds 4186520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4187520c8b16SMiklos Szeredi return -EINVAL; 4188520c8b16SMiklos Szeredi 4189bc27027aSMiklos Szeredi /* 4190bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4191bc27027aSMiklos Szeredi * we'll need to flip '..'. 4192bc27027aSMiklos Szeredi */ 4193da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4194da1ce067SMiklos Szeredi if (is_dir) { 4195bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4196bc27027aSMiklos Szeredi if (error) 4197bc27027aSMiklos Szeredi return error; 4198bc27027aSMiklos Szeredi } 4199da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4200da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4201da1ce067SMiklos Szeredi if (error) 4202da1ce067SMiklos Szeredi return error; 4203da1ce067SMiklos Szeredi } 4204da1ce067SMiklos Szeredi } 42050eeca283SRobert Love 42060b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 42070b3974ebSMiklos Szeredi flags); 4208bc27027aSMiklos Szeredi if (error) 4209bc27027aSMiklos Szeredi return error; 4210bc27027aSMiklos Szeredi 4211bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4212bc27027aSMiklos Szeredi dget(new_dentry); 4213da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4214bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4215bc27027aSMiklos Szeredi else if (target) 4216bc27027aSMiklos Szeredi mutex_lock(&target->i_mutex); 4217bc27027aSMiklos Szeredi 4218bc27027aSMiklos Szeredi error = -EBUSY; 42197af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4220bc27027aSMiklos Szeredi goto out; 4221bc27027aSMiklos Szeredi 4222da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4223bc27027aSMiklos Szeredi error = -EMLINK; 4224da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4225bc27027aSMiklos Szeredi goto out; 4226da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4227da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4228da1ce067SMiklos Szeredi goto out; 4229da1ce067SMiklos Szeredi } 4230da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4231bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4232da1ce067SMiklos Szeredi if (!is_dir) { 4233bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4234bc27027aSMiklos Szeredi if (error) 4235bc27027aSMiklos Szeredi goto out; 4236da1ce067SMiklos Szeredi } 4237da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4238bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4239bc27027aSMiklos Szeredi if (error) 4240bc27027aSMiklos Szeredi goto out; 4241bc27027aSMiklos Szeredi } 42427177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4243520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4244520c8b16SMiklos Szeredi new_dir, new_dentry); 4245520c8b16SMiklos Szeredi } else { 42467177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4247520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4248520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4249520c8b16SMiklos Szeredi } 4250bc27027aSMiklos Szeredi if (error) 4251bc27027aSMiklos Szeredi goto out; 4252bc27027aSMiklos Szeredi 4253da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 42541da177e4SLinus Torvalds if (is_dir) 4255bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4256bc27027aSMiklos Szeredi dont_mount(new_dentry); 42578ed936b5SEric W. Biederman detach_mounts(new_dentry); 4258bc27027aSMiklos Szeredi } 4259da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4260da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4261bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4262da1ce067SMiklos Szeredi else 4263da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4264da1ce067SMiklos Szeredi } 4265bc27027aSMiklos Szeredi out: 4266da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4267bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4268bc27027aSMiklos Szeredi else if (target) 4269bc27027aSMiklos Szeredi mutex_unlock(&target->i_mutex); 4270bc27027aSMiklos Szeredi dput(new_dentry); 4271da1ce067SMiklos Szeredi if (!error) { 4272123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4273da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4274da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4275da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4276da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4277da1ce067SMiklos Szeredi } 4278da1ce067SMiklos Szeredi } 42790eeca283SRobert Love fsnotify_oldname_free(old_name); 42800eeca283SRobert Love 42811da177e4SLinus Torvalds return error; 42821da177e4SLinus Torvalds } 42834d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 42841da177e4SLinus Torvalds 4285520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4286520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 42871da177e4SLinus Torvalds { 42881da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 42891da177e4SLinus Torvalds struct dentry *trap; 4290f5beed75SAl Viro struct path old_path, new_path; 4291f5beed75SAl Viro struct qstr old_last, new_last; 4292f5beed75SAl Viro int old_type, new_type; 42938e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 429491a27b2aSJeff Layton struct filename *from; 429591a27b2aSJeff Layton struct filename *to; 4296f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4297c6a94284SJeff Layton bool should_retry = false; 42982ad94ae6SAl Viro int error; 4299520c8b16SMiklos Szeredi 43000d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4301da1ce067SMiklos Szeredi return -EINVAL; 4302da1ce067SMiklos Szeredi 43030d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 43040d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4305520c8b16SMiklos Szeredi return -EINVAL; 4306520c8b16SMiklos Szeredi 43070d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 43080d7a8555SMiklos Szeredi return -EPERM; 43090d7a8555SMiklos Szeredi 4310f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4311f5beed75SAl Viro target_flags = 0; 4312f5beed75SAl Viro 4313c6a94284SJeff Layton retry: 4314f5beed75SAl Viro from = user_path_parent(olddfd, oldname, 4315f5beed75SAl Viro &old_path, &old_last, &old_type, lookup_flags); 431691a27b2aSJeff Layton if (IS_ERR(from)) { 431791a27b2aSJeff Layton error = PTR_ERR(from); 43181da177e4SLinus Torvalds goto exit; 431991a27b2aSJeff Layton } 43201da177e4SLinus Torvalds 4321f5beed75SAl Viro to = user_path_parent(newdfd, newname, 4322f5beed75SAl Viro &new_path, &new_last, &new_type, lookup_flags); 432391a27b2aSJeff Layton if (IS_ERR(to)) { 432491a27b2aSJeff Layton error = PTR_ERR(to); 43251da177e4SLinus Torvalds goto exit1; 432691a27b2aSJeff Layton } 43271da177e4SLinus Torvalds 43281da177e4SLinus Torvalds error = -EXDEV; 4329f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 43301da177e4SLinus Torvalds goto exit2; 43311da177e4SLinus Torvalds 43321da177e4SLinus Torvalds error = -EBUSY; 4333f5beed75SAl Viro if (old_type != LAST_NORM) 43341da177e4SLinus Torvalds goto exit2; 43351da177e4SLinus Torvalds 43360a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 43370a7c3937SMiklos Szeredi error = -EEXIST; 4338f5beed75SAl Viro if (new_type != LAST_NORM) 43391da177e4SLinus Torvalds goto exit2; 43401da177e4SLinus Torvalds 4341f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4342c30dabfeSJan Kara if (error) 4343c30dabfeSJan Kara goto exit2; 4344c30dabfeSJan Kara 43458e6d782cSJ. Bruce Fields retry_deleg: 4346f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 43471da177e4SLinus Torvalds 4348f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 43491da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 43501da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 43511da177e4SLinus Torvalds goto exit3; 43521da177e4SLinus Torvalds /* source must exist */ 43531da177e4SLinus Torvalds error = -ENOENT; 4354b18825a7SDavid Howells if (d_is_negative(old_dentry)) 43551da177e4SLinus Torvalds goto exit4; 4356f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 43571da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 43581da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 43591da177e4SLinus Torvalds goto exit4; 43600a7c3937SMiklos Szeredi error = -EEXIST; 43610a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 43620a7c3937SMiklos Szeredi goto exit5; 4363da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4364da1ce067SMiklos Szeredi error = -ENOENT; 4365da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4366da1ce067SMiklos Szeredi goto exit5; 4367da1ce067SMiklos Szeredi 4368da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4369da1ce067SMiklos Szeredi error = -ENOTDIR; 4370f5beed75SAl Viro if (new_last.name[new_last.len]) 4371da1ce067SMiklos Szeredi goto exit5; 4372da1ce067SMiklos Szeredi } 4373da1ce067SMiklos Szeredi } 43740a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 43750a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 43760a7c3937SMiklos Szeredi error = -ENOTDIR; 4377f5beed75SAl Viro if (old_last.name[old_last.len]) 43780a7c3937SMiklos Szeredi goto exit5; 4379f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 43800a7c3937SMiklos Szeredi goto exit5; 43810a7c3937SMiklos Szeredi } 43820a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 43830a7c3937SMiklos Szeredi error = -EINVAL; 43840a7c3937SMiklos Szeredi if (old_dentry == trap) 43850a7c3937SMiklos Szeredi goto exit5; 43861da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4387da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43881da177e4SLinus Torvalds error = -ENOTEMPTY; 43891da177e4SLinus Torvalds if (new_dentry == trap) 43901da177e4SLinus Torvalds goto exit5; 43911da177e4SLinus Torvalds 4392f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4393f5beed75SAl Viro &new_path, new_dentry, flags); 4394be6d3e56SKentaro Takeda if (error) 4395c30dabfeSJan Kara goto exit5; 4396f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4397f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4398520c8b16SMiklos Szeredi &delegated_inode, flags); 43991da177e4SLinus Torvalds exit5: 44001da177e4SLinus Torvalds dput(new_dentry); 44011da177e4SLinus Torvalds exit4: 44021da177e4SLinus Torvalds dput(old_dentry); 44031da177e4SLinus Torvalds exit3: 4404f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 44058e6d782cSJ. Bruce Fields if (delegated_inode) { 44068e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 44078e6d782cSJ. Bruce Fields if (!error) 44088e6d782cSJ. Bruce Fields goto retry_deleg; 44098e6d782cSJ. Bruce Fields } 4410f5beed75SAl Viro mnt_drop_write(old_path.mnt); 44111da177e4SLinus Torvalds exit2: 4412c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4413c6a94284SJeff Layton should_retry = true; 4414f5beed75SAl Viro path_put(&new_path); 44152ad94ae6SAl Viro putname(to); 44161da177e4SLinus Torvalds exit1: 4417f5beed75SAl Viro path_put(&old_path); 44181da177e4SLinus Torvalds putname(from); 4419c6a94284SJeff Layton if (should_retry) { 4420c6a94284SJeff Layton should_retry = false; 4421c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4422c6a94284SJeff Layton goto retry; 4423c6a94284SJeff Layton } 44242ad94ae6SAl Viro exit: 44251da177e4SLinus Torvalds return error; 44261da177e4SLinus Torvalds } 44271da177e4SLinus Torvalds 4428520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4429520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4430520c8b16SMiklos Szeredi { 4431520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4432520c8b16SMiklos Szeredi } 4433520c8b16SMiklos Szeredi 4434a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 44355590ff0dSUlrich Drepper { 4436520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 44375590ff0dSUlrich Drepper } 44385590ff0dSUlrich Drepper 4439787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4440787fb6bcSMiklos Szeredi { 4441787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4442787fb6bcSMiklos Szeredi if (error) 4443787fb6bcSMiklos Szeredi return error; 4444787fb6bcSMiklos Szeredi 4445787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4446787fb6bcSMiklos Szeredi return -EPERM; 4447787fb6bcSMiklos Szeredi 4448787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4449787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4450787fb6bcSMiklos Szeredi } 4451787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4452787fb6bcSMiklos Szeredi 44535d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 44541da177e4SLinus Torvalds { 44555d826c84SAl Viro int len = PTR_ERR(link); 44561da177e4SLinus Torvalds if (IS_ERR(link)) 44571da177e4SLinus Torvalds goto out; 44581da177e4SLinus Torvalds 44591da177e4SLinus Torvalds len = strlen(link); 44601da177e4SLinus Torvalds if (len > (unsigned) buflen) 44611da177e4SLinus Torvalds len = buflen; 44621da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 44631da177e4SLinus Torvalds len = -EFAULT; 44641da177e4SLinus Torvalds out: 44651da177e4SLinus Torvalds return len; 44661da177e4SLinus Torvalds } 44675d826c84SAl Viro EXPORT_SYMBOL(readlink_copy); 44681da177e4SLinus Torvalds 44691da177e4SLinus Torvalds /* 44701da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 44711da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 44721da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 44731da177e4SLinus Torvalds */ 44741da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44751da177e4SLinus Torvalds { 4476cc314eefSLinus Torvalds void *cookie; 4477d4dee48bSAl Viro const char *link = dentry->d_inode->i_link; 4478694a1764SMarcin Slusarz int res; 4479cc314eefSLinus Torvalds 4480d4dee48bSAl Viro if (!link) { 44816e77137bSAl Viro link = dentry->d_inode->i_op->follow_link(dentry, &cookie); 4482680baacbSAl Viro if (IS_ERR(link)) 4483680baacbSAl Viro return PTR_ERR(link); 4484d4dee48bSAl Viro } 4485680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 44866e77137bSAl Viro if (dentry->d_inode->i_op->put_link) 4487680baacbSAl Viro dentry->d_inode->i_op->put_link(dentry, cookie); 4488694a1764SMarcin Slusarz return res; 44891da177e4SLinus Torvalds } 44904d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 44911da177e4SLinus Torvalds 44921da177e4SLinus Torvalds /* get the link contents into pagecache */ 44931da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 44941da177e4SLinus Torvalds { 4495ebd09abbSDuane Griffin char *kaddr; 44961da177e4SLinus Torvalds struct page *page; 44971da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 4498090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 44991da177e4SLinus Torvalds if (IS_ERR(page)) 45006fe6900eSNick Piggin return (char*)page; 45011da177e4SLinus Torvalds *ppage = page; 4502ebd09abbSDuane Griffin kaddr = kmap(page); 4503ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 4504ebd09abbSDuane Griffin return kaddr; 45051da177e4SLinus Torvalds } 45061da177e4SLinus Torvalds 45071da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 45081da177e4SLinus Torvalds { 45091da177e4SLinus Torvalds struct page *page = NULL; 45105d826c84SAl Viro int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); 45111da177e4SLinus Torvalds if (page) { 45121da177e4SLinus Torvalds kunmap(page); 45131da177e4SLinus Torvalds page_cache_release(page); 45141da177e4SLinus Torvalds } 45151da177e4SLinus Torvalds return res; 45161da177e4SLinus Torvalds } 45174d359507SAl Viro EXPORT_SYMBOL(page_readlink); 45181da177e4SLinus Torvalds 45196e77137bSAl Viro const char *page_follow_link_light(struct dentry *dentry, void **cookie) 45201da177e4SLinus Torvalds { 4521cc314eefSLinus Torvalds struct page *page = NULL; 4522680baacbSAl Viro char *res = page_getlink(dentry, &page); 4523680baacbSAl Viro if (!IS_ERR(res)) 4524680baacbSAl Viro *cookie = page; 4525680baacbSAl Viro return res; 45261da177e4SLinus Torvalds } 45274d359507SAl Viro EXPORT_SYMBOL(page_follow_link_light); 45281da177e4SLinus Torvalds 4529680baacbSAl Viro void page_put_link(struct dentry *dentry, void *cookie) 45301da177e4SLinus Torvalds { 4531cc314eefSLinus Torvalds struct page *page = cookie; 45321da177e4SLinus Torvalds kunmap(page); 45331da177e4SLinus Torvalds page_cache_release(page); 45341da177e4SLinus Torvalds } 45354d359507SAl Viro EXPORT_SYMBOL(page_put_link); 45361da177e4SLinus Torvalds 453754566b2cSNick Piggin /* 453854566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 453954566b2cSNick Piggin */ 454054566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 45411da177e4SLinus Torvalds { 45421da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 45430adb25d2SKirill Korotaev struct page *page; 4544afddba49SNick Piggin void *fsdata; 4545beb497abSDmitriy Monakhov int err; 45461da177e4SLinus Torvalds char *kaddr; 454754566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 454854566b2cSNick Piggin if (nofs) 454954566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 45501da177e4SLinus Torvalds 45517e53cac4SNeilBrown retry: 4552afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 455354566b2cSNick Piggin flags, &page, &fsdata); 45541da177e4SLinus Torvalds if (err) 4555afddba49SNick Piggin goto fail; 4556afddba49SNick Piggin 4557e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 45581da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 4559e8e3c3d6SCong Wang kunmap_atomic(kaddr); 4560afddba49SNick Piggin 4561afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4562afddba49SNick Piggin page, fsdata); 45631da177e4SLinus Torvalds if (err < 0) 45641da177e4SLinus Torvalds goto fail; 4565afddba49SNick Piggin if (err < len-1) 4566afddba49SNick Piggin goto retry; 4567afddba49SNick Piggin 45681da177e4SLinus Torvalds mark_inode_dirty(inode); 45691da177e4SLinus Torvalds return 0; 45701da177e4SLinus Torvalds fail: 45711da177e4SLinus Torvalds return err; 45721da177e4SLinus Torvalds } 45734d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 45741da177e4SLinus Torvalds 45750adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 45760adb25d2SKirill Korotaev { 45770adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 457854566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 45790adb25d2SKirill Korotaev } 45804d359507SAl Viro EXPORT_SYMBOL(page_symlink); 45810adb25d2SKirill Korotaev 458292e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 45831da177e4SLinus Torvalds .readlink = generic_readlink, 45841da177e4SLinus Torvalds .follow_link = page_follow_link_light, 45851da177e4SLinus Torvalds .put_link = page_put_link, 45861da177e4SLinus Torvalds }; 45871da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4588