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; 5065e53084dSAl Viro struct file *base; 507697fc6caSAl Viro struct saved { 508697fc6caSAl Viro struct path link; 509697fc6caSAl Viro void *cookie; 510697fc6caSAl Viro const char *name; 511894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5121f55a6ecSAl Viro }; 5131f55a6ecSAl Viro 514756daf26SNeilBrown static struct nameidata *set_nameidata(struct nameidata *p) 515894bc8c4SAl Viro { 516756daf26SNeilBrown struct nameidata *old = current->nameidata; 517756daf26SNeilBrown p->stack = p->internal; 518756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 519756daf26SNeilBrown current->nameidata = p; 520756daf26SNeilBrown return old; 521894bc8c4SAl Viro } 522894bc8c4SAl Viro 523756daf26SNeilBrown static void restore_nameidata(struct nameidata *old) 524894bc8c4SAl Viro { 525756daf26SNeilBrown struct nameidata *now = current->nameidata; 526756daf26SNeilBrown 527756daf26SNeilBrown current->nameidata = old; 528756daf26SNeilBrown if (old) 529756daf26SNeilBrown old->total_link_count = now->total_link_count; 530756daf26SNeilBrown if (now->stack != now->internal) { 531756daf26SNeilBrown kfree(now->stack); 532756daf26SNeilBrown now->stack = now->internal; 533894bc8c4SAl Viro } 534894bc8c4SAl Viro } 535894bc8c4SAl Viro 536894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 537894bc8c4SAl Viro { 538e269f2a7SAl Viro struct saved *p = kmalloc(MAXSYMLINKS * sizeof(struct saved), 539894bc8c4SAl Viro GFP_KERNEL); 540894bc8c4SAl Viro if (unlikely(!p)) 541894bc8c4SAl Viro return -ENOMEM; 542894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 543894bc8c4SAl Viro nd->stack = p; 544894bc8c4SAl Viro return 0; 545894bc8c4SAl Viro } 546894bc8c4SAl Viro 547894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 548894bc8c4SAl Viro { 549da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 550894bc8c4SAl Viro return 0; 551894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 552894bc8c4SAl Viro return 0; 553894bc8c4SAl Viro return __nd_alloc_stack(nd); 554894bc8c4SAl Viro } 555894bc8c4SAl Viro 55619660af7SAl Viro /* 55731e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 55819660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 55919660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 56019660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 56119660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 56219660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 56319660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 56419660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 56531e6b01fSNick Piggin */ 56631e6b01fSNick Piggin 567e8bb73dfSAl Viro static void terminate_walk(struct nameidata *nd); 568e8bb73dfSAl Viro 56931e6b01fSNick Piggin /** 57019660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 57119660af7SAl Viro * @nd: nameidata pathwalk data 57219660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 57339191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 57431e6b01fSNick Piggin * 57519660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 57619660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 57719660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 57831e6b01fSNick Piggin */ 57919660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 58031e6b01fSNick Piggin { 58131e6b01fSNick Piggin struct fs_struct *fs = current->fs; 58231e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 58331e6b01fSNick Piggin 58431e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 585e5c832d5SLinus Torvalds 586e5c832d5SLinus Torvalds /* 58748a066e7SAl Viro * After legitimizing the bastards, terminate_walk() 58848a066e7SAl Viro * will do the right thing for non-RCU mode, and all our 58948a066e7SAl Viro * subsequent exit cases should rcu_read_unlock() 59048a066e7SAl Viro * before returning. Do vfsmount first; if dentry 59148a066e7SAl Viro * can't be legitimized, just set nd->path.dentry to NULL 59248a066e7SAl Viro * and rely on dput(NULL) being a no-op. 593e5c832d5SLinus Torvalds */ 59448a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) 595e5c832d5SLinus Torvalds return -ECHILD; 596e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 59715570086SLinus Torvalds 59848a066e7SAl Viro if (!lockref_get_not_dead(&parent->d_lockref)) { 59948a066e7SAl Viro nd->path.dentry = NULL; 600d870b4a1SAl Viro goto out; 60148a066e7SAl Viro } 60248a066e7SAl Viro 60315570086SLinus Torvalds /* 60415570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 60515570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 60615570086SLinus Torvalds * 60715570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 60815570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 60915570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 61015570086SLinus Torvalds * since we checked the sequence number of the parent after we got 61115570086SLinus Torvalds * the child sequence number. So we know the parent must still 61215570086SLinus Torvalds * be valid if the child sequence number is still valid. 61315570086SLinus Torvalds */ 61419660af7SAl Viro if (!dentry) { 615e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 616e5c832d5SLinus Torvalds goto out; 61719660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 61819660af7SAl Viro } else { 619e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 620e5c832d5SLinus Torvalds goto out; 621e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) 622e5c832d5SLinus Torvalds goto drop_dentry; 62319660af7SAl Viro } 624e5c832d5SLinus Torvalds 625e5c832d5SLinus Torvalds /* 626e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 627e5c832d5SLinus Torvalds * still valid and get it if required. 628e5c832d5SLinus Torvalds */ 629e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 630e5c832d5SLinus Torvalds spin_lock(&fs->lock); 631e5c832d5SLinus Torvalds if (nd->root.mnt != fs->root.mnt || nd->root.dentry != fs->root.dentry) 632e5c832d5SLinus Torvalds goto unlock_and_drop_dentry; 63331e6b01fSNick Piggin path_get(&nd->root); 63431e6b01fSNick Piggin spin_unlock(&fs->lock); 63531e6b01fSNick Piggin } 63631e6b01fSNick Piggin 6378b61e74fSAl Viro rcu_read_unlock(); 63831e6b01fSNick Piggin return 0; 63919660af7SAl Viro 640e5c832d5SLinus Torvalds unlock_and_drop_dentry: 64131e6b01fSNick Piggin spin_unlock(&fs->lock); 642e5c832d5SLinus Torvalds drop_dentry: 6438b61e74fSAl Viro rcu_read_unlock(); 644e5c832d5SLinus Torvalds dput(dentry); 645d0d27277SLinus Torvalds goto drop_root_mnt; 646e5c832d5SLinus Torvalds out: 6478b61e74fSAl Viro rcu_read_unlock(); 648d0d27277SLinus Torvalds drop_root_mnt: 649d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 650d0d27277SLinus Torvalds nd->root.mnt = NULL; 65131e6b01fSNick Piggin return -ECHILD; 65231e6b01fSNick Piggin } 65331e6b01fSNick Piggin 6544ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 65534286d66SNick Piggin { 6564ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 65734286d66SNick Piggin } 65834286d66SNick Piggin 6599f1fafeeSAl Viro /** 6609f1fafeeSAl Viro * complete_walk - successful completion of path walk 6619f1fafeeSAl Viro * @nd: pointer nameidata 66239159de2SJeff Layton * 6639f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 6649f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 6659f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 6669f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 6679f1fafeeSAl Viro * need to drop nd->path. 66839159de2SJeff Layton */ 6699f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 67039159de2SJeff Layton { 67116c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 67239159de2SJeff Layton int status; 67339159de2SJeff Layton 6749f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 6759f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6769f1fafeeSAl Viro nd->root.mnt = NULL; 677e8bb73dfSAl Viro if (unlikely(unlazy_walk(nd, NULL))) { 678e8bb73dfSAl Viro terminate_walk(nd); 67948a066e7SAl Viro return -ECHILD; 68048a066e7SAl Viro } 6819f1fafeeSAl Viro } 6829f1fafeeSAl Viro 68316c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 68439159de2SJeff Layton return 0; 68539159de2SJeff Layton 686ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 68716c2cd71SAl Viro return 0; 68816c2cd71SAl Viro 689ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 69039159de2SJeff Layton if (status > 0) 69139159de2SJeff Layton return 0; 69239159de2SJeff Layton 69316c2cd71SAl Viro if (!status) 69439159de2SJeff Layton status = -ESTALE; 69516c2cd71SAl Viro 696e8bb73dfSAl Viro terminate_walk(nd); 69739159de2SJeff Layton return status; 69839159de2SJeff Layton } 69939159de2SJeff Layton 7002a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 7012a737871SAl Viro { 702f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 7032a737871SAl Viro } 7042a737871SAl Viro 7057bd88377SAl Viro static __always_inline unsigned set_root_rcu(struct nameidata *nd) 70631e6b01fSNick Piggin { 70731e6b01fSNick Piggin struct fs_struct *fs = current->fs; 7087bd88377SAl Viro unsigned seq, res; 709c28cc364SNick Piggin 710c28cc364SNick Piggin do { 711c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 71231e6b01fSNick Piggin nd->root = fs->root; 7137bd88377SAl Viro res = __read_seqcount_begin(&nd->root.dentry->d_seq); 714c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 7157bd88377SAl Viro return res; 71631e6b01fSNick Piggin } 71731e6b01fSNick Piggin 7181d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 719051d3812SIan Kent { 720051d3812SIan Kent dput(path->dentry); 7214ac91378SJan Blunck if (path->mnt != nd->path.mnt) 722051d3812SIan Kent mntput(path->mnt); 723051d3812SIan Kent } 724051d3812SIan Kent 7257b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 7267b9337aaSNick Piggin struct nameidata *nd) 727051d3812SIan Kent { 72831e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 7294ac91378SJan Blunck dput(nd->path.dentry); 73031e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 7314ac91378SJan Blunck mntput(nd->path.mnt); 7329a229683SHuang Shijie } 73331e6b01fSNick Piggin nd->path.mnt = path->mnt; 7344ac91378SJan Blunck nd->path.dentry = path->dentry; 735051d3812SIan Kent } 736051d3812SIan Kent 737b5fb63c1SChristoph Hellwig /* 738b5fb63c1SChristoph Hellwig * Helper to directly jump to a known parsed path from ->follow_link, 739b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 740b5fb63c1SChristoph Hellwig */ 7416e77137bSAl Viro void nd_jump_link(struct path *path) 742b5fb63c1SChristoph Hellwig { 7436e77137bSAl Viro struct nameidata *nd = current->nameidata; 744b5fb63c1SChristoph Hellwig path_put(&nd->path); 745b5fb63c1SChristoph Hellwig 746b5fb63c1SChristoph Hellwig nd->path = *path; 747b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 748b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 749b5fb63c1SChristoph Hellwig } 750b5fb63c1SChristoph Hellwig 751b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 752574197e0SAl Viro { 75321c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 754b9ff4429SAl Viro struct inode *inode = last->link.dentry->d_inode; 755b9ff4429SAl Viro if (last->cookie && inode->i_op->put_link) 756b9ff4429SAl Viro inode->i_op->put_link(last->link.dentry, last->cookie); 757b9ff4429SAl Viro path_put(&last->link); 758574197e0SAl Viro } 759574197e0SAl Viro 760561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 761561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 762800179c9SKees Cook 763800179c9SKees Cook /** 764800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 76555852635SRandy Dunlap * @nd: nameidata pathwalk data 766800179c9SKees Cook * 767800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 768800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 769800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 770800179c9SKees Cook * processes from failing races against path names that may change out 771800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 772800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 773800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 774800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 775800179c9SKees Cook * 776800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 777800179c9SKees Cook */ 778fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 779800179c9SKees Cook { 780800179c9SKees Cook const struct inode *inode; 781800179c9SKees Cook const struct inode *parent; 782800179c9SKees Cook 783800179c9SKees Cook if (!sysctl_protected_symlinks) 784800179c9SKees Cook return 0; 785800179c9SKees Cook 786800179c9SKees Cook /* Allowed if owner and follower match. */ 7871cf2665bSAl Viro inode = nd->stack[0].link.dentry->d_inode; 78881abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 789800179c9SKees Cook return 0; 790800179c9SKees Cook 791800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 792800179c9SKees Cook parent = nd->path.dentry->d_inode; 793800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 794800179c9SKees Cook return 0; 795800179c9SKees Cook 796800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 79781abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 798800179c9SKees Cook return 0; 799800179c9SKees Cook 8001cf2665bSAl Viro audit_log_link_denied("follow_link", &nd->stack[0].link); 8011cf2665bSAl Viro path_put(&nd->stack[0].link); 802800179c9SKees Cook path_put(&nd->path); 803800179c9SKees Cook return -EACCES; 804800179c9SKees Cook } 805800179c9SKees Cook 806800179c9SKees Cook /** 807800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 808800179c9SKees Cook * @inode: the source inode to hardlink from 809800179c9SKees Cook * 810800179c9SKees Cook * Return false if at least one of the following conditions: 811800179c9SKees Cook * - inode is not a regular file 812800179c9SKees Cook * - inode is setuid 813800179c9SKees Cook * - inode is setgid and group-exec 814800179c9SKees Cook * - access failure for read and write 815800179c9SKees Cook * 816800179c9SKees Cook * Otherwise returns true. 817800179c9SKees Cook */ 818800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 819800179c9SKees Cook { 820800179c9SKees Cook umode_t mode = inode->i_mode; 821800179c9SKees Cook 822800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 823800179c9SKees Cook if (!S_ISREG(mode)) 824800179c9SKees Cook return false; 825800179c9SKees Cook 826800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 827800179c9SKees Cook if (mode & S_ISUID) 828800179c9SKees Cook return false; 829800179c9SKees Cook 830800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 831800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 832800179c9SKees Cook return false; 833800179c9SKees Cook 834800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 835800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 836800179c9SKees Cook return false; 837800179c9SKees Cook 838800179c9SKees Cook return true; 839800179c9SKees Cook } 840800179c9SKees Cook 841800179c9SKees Cook /** 842800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 843800179c9SKees Cook * @link: the source to hardlink from 844800179c9SKees Cook * 845800179c9SKees Cook * Block hardlink when all of: 846800179c9SKees Cook * - sysctl_protected_hardlinks enabled 847800179c9SKees Cook * - fsuid does not match inode 848800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 849800179c9SKees Cook * - not CAP_FOWNER 850800179c9SKees Cook * 851800179c9SKees Cook * Returns 0 if successful, -ve on error. 852800179c9SKees Cook */ 853800179c9SKees Cook static int may_linkat(struct path *link) 854800179c9SKees Cook { 855800179c9SKees Cook const struct cred *cred; 856800179c9SKees Cook struct inode *inode; 857800179c9SKees Cook 858800179c9SKees Cook if (!sysctl_protected_hardlinks) 859800179c9SKees Cook return 0; 860800179c9SKees Cook 861800179c9SKees Cook cred = current_cred(); 862800179c9SKees Cook inode = link->dentry->d_inode; 863800179c9SKees Cook 864800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 865800179c9SKees Cook * otherwise, it must be a safe source. 866800179c9SKees Cook */ 86781abe27bSEric W. Biederman if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || 868800179c9SKees Cook capable(CAP_FOWNER)) 869800179c9SKees Cook return 0; 870800179c9SKees Cook 871a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 872800179c9SKees Cook return -EPERM; 873800179c9SKees Cook } 874800179c9SKees Cook 8753b2e7f75SAl Viro static __always_inline 8763b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 8771da177e4SLinus Torvalds { 8783b2e7f75SAl Viro struct saved *last = nd->stack + nd->depth; 8791cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 8800a959df5SAl Viro struct inode *inode = dentry->d_inode; 8816d7b5aaeSAl Viro int error; 8820a959df5SAl Viro const char *res; 8831da177e4SLinus Torvalds 884844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 885844a3917SAl Viro 8863b2e7f75SAl Viro last->cookie = NULL; 8876920a440SAl Viro nd->depth++; 8886d7b5aaeSAl Viro 889574197e0SAl Viro cond_resched(); 890574197e0SAl Viro 8913b2e7f75SAl Viro touch_atime(&last->link); 892cd4e91d3SAl Viro 89337882db0SNeilBrown error = security_inode_follow_link(dentry); 8946d7b5aaeSAl Viro if (error) 8956920a440SAl Viro return ERR_PTR(error); 89636f3b4f6SAl Viro 89786acdca1SAl Viro nd->last_type = LAST_BIND; 898d4dee48bSAl Viro res = inode->i_link; 899d4dee48bSAl Viro if (!res) { 9006e77137bSAl Viro res = inode->i_op->follow_link(dentry, &last->cookie); 901fab51e8aSAl Viro if (IS_ERR_OR_NULL(res)) { 9026920a440SAl Viro last->cookie = NULL; 903fab51e8aSAl Viro return res; 9040a959df5SAl Viro } 905fab51e8aSAl Viro } 906fab51e8aSAl Viro if (*res == '/') { 907fab51e8aSAl Viro if (!nd->root.mnt) 908fab51e8aSAl Viro set_root(nd); 909fab51e8aSAl Viro path_put(&nd->path); 910fab51e8aSAl Viro nd->path = nd->root; 911fab51e8aSAl Viro path_get(&nd->root); 912fab51e8aSAl Viro nd->inode = nd->path.dentry->d_inode; 913fab51e8aSAl Viro nd->flags |= LOOKUP_JUMPED; 914fab51e8aSAl Viro while (unlikely(*++res == '/')) 915fab51e8aSAl Viro ; 916fab51e8aSAl Viro } 917fab51e8aSAl Viro if (!*res) 918fab51e8aSAl Viro res = NULL; 9190a959df5SAl Viro return res; 9200a959df5SAl Viro } 9216d7b5aaeSAl Viro 92231e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 92331e6b01fSNick Piggin { 9240714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9250714a533SAl Viro struct mount *parent; 92631e6b01fSNick Piggin struct dentry *mountpoint; 92731e6b01fSNick Piggin 9280714a533SAl Viro parent = mnt->mnt_parent; 9290714a533SAl Viro if (&parent->mnt == path->mnt) 93031e6b01fSNick Piggin return 0; 931a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 93231e6b01fSNick Piggin path->dentry = mountpoint; 9330714a533SAl Viro path->mnt = &parent->mnt; 93431e6b01fSNick Piggin return 1; 93531e6b01fSNick Piggin } 93631e6b01fSNick Piggin 937f015f126SDavid Howells /* 938f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 939f015f126SDavid Howells * 940f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 941f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 942f015f126SDavid Howells * Up is towards /. 943f015f126SDavid Howells * 944f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 945f015f126SDavid Howells * root. 946f015f126SDavid Howells */ 947bab77ebfSAl Viro int follow_up(struct path *path) 9481da177e4SLinus Torvalds { 9490714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9500714a533SAl Viro struct mount *parent; 9511da177e4SLinus Torvalds struct dentry *mountpoint; 95299b7db7bSNick Piggin 95348a066e7SAl Viro read_seqlock_excl(&mount_lock); 9540714a533SAl Viro parent = mnt->mnt_parent; 9553c0a6163SAl Viro if (parent == mnt) { 95648a066e7SAl Viro read_sequnlock_excl(&mount_lock); 9571da177e4SLinus Torvalds return 0; 9581da177e4SLinus Torvalds } 9590714a533SAl Viro mntget(&parent->mnt); 960a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 96148a066e7SAl Viro read_sequnlock_excl(&mount_lock); 962bab77ebfSAl Viro dput(path->dentry); 963bab77ebfSAl Viro path->dentry = mountpoint; 964bab77ebfSAl Viro mntput(path->mnt); 9650714a533SAl Viro path->mnt = &parent->mnt; 9661da177e4SLinus Torvalds return 1; 9671da177e4SLinus Torvalds } 9684d359507SAl Viro EXPORT_SYMBOL(follow_up); 9691da177e4SLinus Torvalds 970b5c84bf6SNick Piggin /* 9719875cf80SDavid Howells * Perform an automount 9729875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 9739875cf80SDavid Howells * were called with. 9741da177e4SLinus Torvalds */ 975756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 9769875cf80SDavid Howells bool *need_mntput) 97731e6b01fSNick Piggin { 9789875cf80SDavid Howells struct vfsmount *mnt; 979ea5b778aSDavid Howells int err; 9809875cf80SDavid Howells 9819875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 9829875cf80SDavid Howells return -EREMOTE; 9839875cf80SDavid Howells 9840ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 9850ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 9860ec26fd0SMiklos Szeredi * the name. 9870ec26fd0SMiklos Szeredi * 9880ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 9895a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 9900ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 9910ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 9920ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 9930ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 9945a30d8a2SDavid Howells */ 995756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 996d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 9975a30d8a2SDavid Howells path->dentry->d_inode) 9989875cf80SDavid Howells return -EISDIR; 9990ec26fd0SMiklos Szeredi 1000756daf26SNeilBrown nd->total_link_count++; 1001756daf26SNeilBrown if (nd->total_link_count >= 40) 10029875cf80SDavid Howells return -ELOOP; 10039875cf80SDavid Howells 10049875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 10059875cf80SDavid Howells if (IS_ERR(mnt)) { 10069875cf80SDavid Howells /* 10079875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 10089875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 10099875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 10109875cf80SDavid Howells * 10119875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 10129875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 10139875cf80SDavid Howells * the path is inaccessible and we should say so. 10149875cf80SDavid Howells */ 1015756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 10169875cf80SDavid Howells return -EREMOTE; 10179875cf80SDavid Howells return PTR_ERR(mnt); 101831e6b01fSNick Piggin } 1019ea5b778aSDavid Howells 10209875cf80SDavid Howells if (!mnt) /* mount collision */ 10219875cf80SDavid Howells return 0; 10229875cf80SDavid Howells 10238aef1884SAl Viro if (!*need_mntput) { 10248aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 10258aef1884SAl Viro mntget(path->mnt); 10268aef1884SAl Viro *need_mntput = true; 10278aef1884SAl Viro } 102819a167afSAl Viro err = finish_automount(mnt, path); 1029ea5b778aSDavid Howells 1030ea5b778aSDavid Howells switch (err) { 1031ea5b778aSDavid Howells case -EBUSY: 1032ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 103319a167afSAl Viro return 0; 1034ea5b778aSDavid Howells case 0: 10358aef1884SAl Viro path_put(path); 10369875cf80SDavid Howells path->mnt = mnt; 10379875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 10389875cf80SDavid Howells return 0; 103919a167afSAl Viro default: 104019a167afSAl Viro return err; 10419875cf80SDavid Howells } 104219a167afSAl Viro 1043ea5b778aSDavid Howells } 10449875cf80SDavid Howells 10459875cf80SDavid Howells /* 10469875cf80SDavid Howells * Handle a dentry that is managed in some way. 1047cc53ce53SDavid Howells * - Flagged for transit management (autofs) 10489875cf80SDavid Howells * - Flagged as mountpoint 10499875cf80SDavid Howells * - Flagged as automount point 10509875cf80SDavid Howells * 10519875cf80SDavid Howells * This may only be called in refwalk mode. 10529875cf80SDavid Howells * 10539875cf80SDavid Howells * Serialization is taken care of in namespace.c 10549875cf80SDavid Howells */ 1055756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 10569875cf80SDavid Howells { 10578aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 10589875cf80SDavid Howells unsigned managed; 10599875cf80SDavid Howells bool need_mntput = false; 10608aef1884SAl Viro int ret = 0; 10619875cf80SDavid Howells 10629875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 10639875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 10649875cf80SDavid Howells * the components of that value change under us */ 10659875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 10669875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 10679875cf80SDavid Howells unlikely(managed != 0)) { 1068cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1069cc53ce53SDavid Howells * being held. */ 1070cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1071cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1072cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 10731aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1074cc53ce53SDavid Howells if (ret < 0) 10758aef1884SAl Viro break; 1076cc53ce53SDavid Howells } 1077cc53ce53SDavid Howells 10789875cf80SDavid Howells /* Transit to a mounted filesystem. */ 10799875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 10809875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10819875cf80SDavid Howells if (mounted) { 10829875cf80SDavid Howells dput(path->dentry); 10839875cf80SDavid Howells if (need_mntput) 1084463ffb2eSAl Viro mntput(path->mnt); 1085463ffb2eSAl Viro path->mnt = mounted; 1086463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 10879875cf80SDavid Howells need_mntput = true; 10889875cf80SDavid Howells continue; 1089463ffb2eSAl Viro } 1090463ffb2eSAl Viro 10919875cf80SDavid Howells /* Something is mounted on this dentry in another 10929875cf80SDavid Howells * namespace and/or whatever was mounted there in this 109348a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 109448a066e7SAl Viro * get it */ 10951da177e4SLinus Torvalds } 10969875cf80SDavid Howells 10979875cf80SDavid Howells /* Handle an automount point */ 10989875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1099756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 11009875cf80SDavid Howells if (ret < 0) 11018aef1884SAl Viro break; 11029875cf80SDavid Howells continue; 11039875cf80SDavid Howells } 11049875cf80SDavid Howells 11059875cf80SDavid Howells /* We didn't change the current path point */ 11069875cf80SDavid Howells break; 11079875cf80SDavid Howells } 11088aef1884SAl Viro 11098aef1884SAl Viro if (need_mntput && path->mnt == mnt) 11108aef1884SAl Viro mntput(path->mnt); 11118aef1884SAl Viro if (ret == -EISDIR) 11128aef1884SAl Viro ret = 0; 11138402752eSAl Viro if (need_mntput) 11148402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 11158402752eSAl Viro if (unlikely(ret < 0)) 11168402752eSAl Viro path_put_conditional(path, nd); 11178402752eSAl Viro return ret; 11181da177e4SLinus Torvalds } 11191da177e4SLinus Torvalds 1120cc53ce53SDavid Howells int follow_down_one(struct path *path) 11211da177e4SLinus Torvalds { 11221da177e4SLinus Torvalds struct vfsmount *mounted; 11231da177e4SLinus Torvalds 11241c755af4SAl Viro mounted = lookup_mnt(path); 11251da177e4SLinus Torvalds if (mounted) { 11269393bd07SAl Viro dput(path->dentry); 11279393bd07SAl Viro mntput(path->mnt); 11289393bd07SAl Viro path->mnt = mounted; 11299393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 11301da177e4SLinus Torvalds return 1; 11311da177e4SLinus Torvalds } 11321da177e4SLinus Torvalds return 0; 11331da177e4SLinus Torvalds } 11344d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 11351da177e4SLinus Torvalds 1136b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 113762a7375eSIan Kent { 1138b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1139b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 114062a7375eSIan Kent } 114162a7375eSIan Kent 11429875cf80SDavid Howells /* 1143287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1144287548e4SAl Viro * we meet a managed dentry that would need blocking. 11459875cf80SDavid Howells */ 11469875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1147287548e4SAl Viro struct inode **inode) 11489875cf80SDavid Howells { 114962a7375eSIan Kent for (;;) { 1150c7105365SAl Viro struct mount *mounted; 115162a7375eSIan Kent /* 115262a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 115362a7375eSIan Kent * that wants to block transit. 115462a7375eSIan Kent */ 1155b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1156b8faf035SNeilBrown case -ECHILD: 1157b8faf035SNeilBrown default: 1158ab90911fSDavid Howells return false; 1159b8faf035SNeilBrown case -EISDIR: 1160b8faf035SNeilBrown return true; 1161b8faf035SNeilBrown case 0: 1162b8faf035SNeilBrown break; 1163b8faf035SNeilBrown } 116462a7375eSIan Kent 116562a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1166b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 116762a7375eSIan Kent 1168474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 11699875cf80SDavid Howells if (!mounted) 11709875cf80SDavid Howells break; 1171c7105365SAl Viro path->mnt = &mounted->mnt; 1172c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1173a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 11749875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 117559430262SLinus Torvalds /* 117659430262SLinus Torvalds * Update the inode too. We don't need to re-check the 117759430262SLinus Torvalds * dentry sequence number here after this d_inode read, 117859430262SLinus Torvalds * because a mount-point is always pinned. 117959430262SLinus Torvalds */ 118059430262SLinus Torvalds *inode = path->dentry->d_inode; 11819875cf80SDavid Howells } 1182f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1183b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1184287548e4SAl Viro } 1185287548e4SAl Viro 118631e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 118731e6b01fSNick Piggin { 11884023bfc9SAl Viro struct inode *inode = nd->inode; 11897bd88377SAl Viro if (!nd->root.mnt) 119031e6b01fSNick Piggin set_root_rcu(nd); 119131e6b01fSNick Piggin 119231e6b01fSNick Piggin while (1) { 119331e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 119431e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 119531e6b01fSNick Piggin break; 119631e6b01fSNick Piggin } 119731e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 119831e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 119931e6b01fSNick Piggin struct dentry *parent = old->d_parent; 120031e6b01fSNick Piggin unsigned seq; 120131e6b01fSNick Piggin 12024023bfc9SAl Viro inode = parent->d_inode; 120331e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 120431e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1205ef7562d5SAl Viro goto failed; 120631e6b01fSNick Piggin nd->path.dentry = parent; 120731e6b01fSNick Piggin nd->seq = seq; 120831e6b01fSNick Piggin break; 120931e6b01fSNick Piggin } 121031e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 121131e6b01fSNick Piggin break; 12124023bfc9SAl Viro inode = nd->path.dentry->d_inode; 121331e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 121431e6b01fSNick Piggin } 1215b37199e6SAl Viro while (d_mountpoint(nd->path.dentry)) { 1216b37199e6SAl Viro struct mount *mounted; 1217b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1218b37199e6SAl Viro if (!mounted) 1219b37199e6SAl Viro break; 1220b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1221b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 12224023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1223b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1224f5be3e29SAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1225b37199e6SAl Viro goto failed; 1226b37199e6SAl Viro } 12274023bfc9SAl Viro nd->inode = inode; 122831e6b01fSNick Piggin return 0; 1229ef7562d5SAl Viro 1230ef7562d5SAl Viro failed: 1231ef7562d5SAl Viro return -ECHILD; 123231e6b01fSNick Piggin } 123331e6b01fSNick Piggin 12349875cf80SDavid Howells /* 1235cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1236cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1237cc53ce53SDavid Howells * caller is permitted to proceed or not. 1238cc53ce53SDavid Howells */ 12397cc90cc3SAl Viro int follow_down(struct path *path) 1240cc53ce53SDavid Howells { 1241cc53ce53SDavid Howells unsigned managed; 1242cc53ce53SDavid Howells int ret; 1243cc53ce53SDavid Howells 1244cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1245cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1246cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1247cc53ce53SDavid Howells * being held. 1248cc53ce53SDavid Howells * 1249cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1250cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1251cc53ce53SDavid Howells * other than its daemon the right to mount on its 1252cc53ce53SDavid Howells * superstructure. 1253cc53ce53SDavid Howells * 1254cc53ce53SDavid Howells * The filesystem may sleep at this point. 1255cc53ce53SDavid Howells */ 1256cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1257cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1258cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1259ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 12601aed3e42SAl Viro path->dentry, false); 1261cc53ce53SDavid Howells if (ret < 0) 1262cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1263cc53ce53SDavid Howells } 1264cc53ce53SDavid Howells 1265cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1266cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1267cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1268cc53ce53SDavid Howells if (!mounted) 1269cc53ce53SDavid Howells break; 1270cc53ce53SDavid Howells dput(path->dentry); 1271cc53ce53SDavid Howells mntput(path->mnt); 1272cc53ce53SDavid Howells path->mnt = mounted; 1273cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1274cc53ce53SDavid Howells continue; 1275cc53ce53SDavid Howells } 1276cc53ce53SDavid Howells 1277cc53ce53SDavid Howells /* Don't handle automount points here */ 1278cc53ce53SDavid Howells break; 1279cc53ce53SDavid Howells } 1280cc53ce53SDavid Howells return 0; 1281cc53ce53SDavid Howells } 12824d359507SAl Viro EXPORT_SYMBOL(follow_down); 1283cc53ce53SDavid Howells 1284cc53ce53SDavid Howells /* 12859875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 12869875cf80SDavid Howells */ 12879875cf80SDavid Howells static void follow_mount(struct path *path) 12889875cf80SDavid Howells { 12899875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 12909875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12919875cf80SDavid Howells if (!mounted) 12929875cf80SDavid Howells break; 12939875cf80SDavid Howells dput(path->dentry); 12949875cf80SDavid Howells mntput(path->mnt); 12959875cf80SDavid Howells path->mnt = mounted; 12969875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 12979875cf80SDavid Howells } 12989875cf80SDavid Howells } 12999875cf80SDavid Howells 130031e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 13011da177e4SLinus Torvalds { 13027bd88377SAl Viro if (!nd->root.mnt) 13032a737871SAl Viro set_root(nd); 1304e518ddb7SAndreas Mohr 13051da177e4SLinus Torvalds while(1) { 13064ac91378SJan Blunck struct dentry *old = nd->path.dentry; 13071da177e4SLinus Torvalds 13082a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 13092a737871SAl Viro nd->path.mnt == nd->root.mnt) { 13101da177e4SLinus Torvalds break; 13111da177e4SLinus Torvalds } 13124ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 13133088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 13143088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 13151da177e4SLinus Torvalds dput(old); 13161da177e4SLinus Torvalds break; 13171da177e4SLinus Torvalds } 13183088dd70SAl Viro if (!follow_up(&nd->path)) 13191da177e4SLinus Torvalds break; 13201da177e4SLinus Torvalds } 132179ed0226SAl Viro follow_mount(&nd->path); 132231e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 13231da177e4SLinus Torvalds } 13241da177e4SLinus Torvalds 13251da177e4SLinus Torvalds /* 1326bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1327bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1328bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1329bad61189SMiklos Szeredi * 1330bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1331baa03890SNick Piggin */ 1332bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1333201f956eSAl Viro unsigned int flags, bool *need_lookup) 1334baa03890SNick Piggin { 1335baa03890SNick Piggin struct dentry *dentry; 1336bad61189SMiklos Szeredi int error; 1337baa03890SNick Piggin 1338bad61189SMiklos Szeredi *need_lookup = false; 1339bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1340bad61189SMiklos Szeredi if (dentry) { 134139e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1342201f956eSAl Viro error = d_revalidate(dentry, flags); 1343bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1344bad61189SMiklos Szeredi if (error < 0) { 1345bad61189SMiklos Szeredi dput(dentry); 1346bad61189SMiklos Szeredi return ERR_PTR(error); 13475542aa2fSEric W. Biederman } else { 13485542aa2fSEric W. Biederman d_invalidate(dentry); 1349bad61189SMiklos Szeredi dput(dentry); 1350bad61189SMiklos Szeredi dentry = NULL; 1351bad61189SMiklos Szeredi } 1352bad61189SMiklos Szeredi } 1353bad61189SMiklos Szeredi } 1354bad61189SMiklos Szeredi } 1355baa03890SNick Piggin 1356bad61189SMiklos Szeredi if (!dentry) { 1357bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1358baa03890SNick Piggin if (unlikely(!dentry)) 1359baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1360baa03890SNick Piggin 1361bad61189SMiklos Szeredi *need_lookup = true; 1362baa03890SNick Piggin } 1363baa03890SNick Piggin return dentry; 1364baa03890SNick Piggin } 1365baa03890SNick Piggin 1366baa03890SNick Piggin /* 136713a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 136813a2c3beSJ. Bruce Fields * unhashed. 1369bad61189SMiklos Szeredi * 1370bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 137144396f4bSJosef Bacik */ 1372bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 137372bd866aSAl Viro unsigned int flags) 137444396f4bSJosef Bacik { 137544396f4bSJosef Bacik struct dentry *old; 137644396f4bSJosef Bacik 137744396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1378bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1379e188dc02SMiklos Szeredi dput(dentry); 138044396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1381e188dc02SMiklos Szeredi } 138244396f4bSJosef Bacik 138372bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 138444396f4bSJosef Bacik if (unlikely(old)) { 138544396f4bSJosef Bacik dput(dentry); 138644396f4bSJosef Bacik dentry = old; 138744396f4bSJosef Bacik } 138844396f4bSJosef Bacik return dentry; 138944396f4bSJosef Bacik } 139044396f4bSJosef Bacik 1391a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 139272bd866aSAl Viro struct dentry *base, unsigned int flags) 1393a3255546SAl Viro { 1394bad61189SMiklos Szeredi bool need_lookup; 1395a3255546SAl Viro struct dentry *dentry; 1396a3255546SAl Viro 139772bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1398bad61189SMiklos Szeredi if (!need_lookup) 1399a3255546SAl Viro return dentry; 1400bad61189SMiklos Szeredi 140172bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1402a3255546SAl Viro } 1403a3255546SAl Viro 140444396f4bSJosef Bacik /* 14051da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 14061da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 14071da177e4SLinus Torvalds * It _is_ time-critical. 14081da177e4SLinus Torvalds */ 1409e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 141031e6b01fSNick Piggin struct path *path, struct inode **inode) 14111da177e4SLinus Torvalds { 14124ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 141331e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 14145a18fff2SAl Viro int need_reval = 1; 14155a18fff2SAl Viro int status = 1; 14169875cf80SDavid Howells int err; 14179875cf80SDavid Howells 14183cac260aSAl Viro /* 1419b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1420b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1421b04f784eSNick Piggin * do the non-racy lookup, below. 1422b04f784eSNick Piggin */ 142331e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 142431e6b01fSNick Piggin unsigned seq; 1425766c4cbfSAl Viro bool negative; 1426da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 14275a18fff2SAl Viro if (!dentry) 14285a18fff2SAl Viro goto unlazy; 14295a18fff2SAl Viro 143012f8ad4bSLinus Torvalds /* 143112f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 143212f8ad4bSLinus Torvalds * the dentry name information from lookup. 143312f8ad4bSLinus Torvalds */ 143412f8ad4bSLinus Torvalds *inode = dentry->d_inode; 1435766c4cbfSAl Viro negative = d_is_negative(dentry); 143612f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 143712f8ad4bSLinus Torvalds return -ECHILD; 1438766c4cbfSAl Viro if (negative) 1439766c4cbfSAl Viro return -ENOENT; 144012f8ad4bSLinus Torvalds 144112f8ad4bSLinus Torvalds /* 144212f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 144312f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 144412f8ad4bSLinus Torvalds * 144512f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 144612f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 144712f8ad4bSLinus Torvalds */ 144831e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 144931e6b01fSNick Piggin return -ECHILD; 145031e6b01fSNick Piggin nd->seq = seq; 14515a18fff2SAl Viro 145224643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 14534ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14545a18fff2SAl Viro if (unlikely(status <= 0)) { 14555a18fff2SAl Viro if (status != -ECHILD) 14565a18fff2SAl Viro need_reval = 0; 14575a18fff2SAl Viro goto unlazy; 14585a18fff2SAl Viro } 145924643087SAl Viro } 146031e6b01fSNick Piggin path->mnt = mnt; 146131e6b01fSNick Piggin path->dentry = dentry; 1462b8faf035SNeilBrown if (likely(__follow_mount_rcu(nd, path, inode))) 14639875cf80SDavid Howells return 0; 14645a18fff2SAl Viro unlazy: 146519660af7SAl Viro if (unlazy_walk(nd, dentry)) 14665a18fff2SAl Viro return -ECHILD; 14675a18fff2SAl Viro } else { 1468e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 146924643087SAl Viro } 14705a18fff2SAl Viro 147181e6f520SAl Viro if (unlikely(!dentry)) 147281e6f520SAl Viro goto need_lookup; 14735a18fff2SAl Viro 14745a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 14754ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14765a18fff2SAl Viro if (unlikely(status <= 0)) { 14775a18fff2SAl Viro if (status < 0) { 14785a18fff2SAl Viro dput(dentry); 14795a18fff2SAl Viro return status; 14805a18fff2SAl Viro } 14815542aa2fSEric W. Biederman d_invalidate(dentry); 14825a18fff2SAl Viro dput(dentry); 148381e6f520SAl Viro goto need_lookup; 14845a18fff2SAl Viro } 1485697f514dSMiklos Szeredi 1486766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1487766c4cbfSAl Viro dput(dentry); 1488766c4cbfSAl Viro return -ENOENT; 1489766c4cbfSAl Viro } 14901da177e4SLinus Torvalds path->mnt = mnt; 14911da177e4SLinus Torvalds path->dentry = dentry; 1492756daf26SNeilBrown err = follow_managed(path, nd); 14938402752eSAl Viro if (likely(!err)) 149431e6b01fSNick Piggin *inode = path->dentry->d_inode; 14958402752eSAl Viro return err; 149681e6f520SAl Viro 149781e6f520SAl Viro need_lookup: 1498697f514dSMiklos Szeredi return 1; 1499697f514dSMiklos Szeredi } 1500697f514dSMiklos Szeredi 1501697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1502cc2a5271SAl Viro static int lookup_slow(struct nameidata *nd, struct path *path) 1503697f514dSMiklos Szeredi { 1504697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1505697f514dSMiklos Szeredi 1506697f514dSMiklos Szeredi parent = nd->path.dentry; 150781e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 150881e6f520SAl Viro 150981e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 1510cc2a5271SAl Viro dentry = __lookup_hash(&nd->last, parent, nd->flags); 151181e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 151281e6f520SAl Viro if (IS_ERR(dentry)) 151381e6f520SAl Viro return PTR_ERR(dentry); 1514697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1515697f514dSMiklos Szeredi path->dentry = dentry; 15168402752eSAl Viro return follow_managed(path, nd); 15171da177e4SLinus Torvalds } 15181da177e4SLinus Torvalds 151952094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 152052094c8aSAl Viro { 152152094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 15224ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 152352094c8aSAl Viro if (err != -ECHILD) 152452094c8aSAl Viro return err; 152519660af7SAl Viro if (unlazy_walk(nd, NULL)) 152652094c8aSAl Viro return -ECHILD; 152752094c8aSAl Viro } 15284ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 152952094c8aSAl Viro } 153052094c8aSAl Viro 15319856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 15329856fa1bSAl Viro { 15339856fa1bSAl Viro if (type == LAST_DOTDOT) { 15349856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 153570291aecSAl Viro return follow_dotdot_rcu(nd); 15369856fa1bSAl Viro } else 15379856fa1bSAl Viro follow_dotdot(nd); 15389856fa1bSAl Viro } 15399856fa1bSAl Viro return 0; 15409856fa1bSAl Viro } 15419856fa1bSAl Viro 1542951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1543951361f9SAl Viro { 1544951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1545951361f9SAl Viro path_put(&nd->path); 1546951361f9SAl Viro } else { 1547951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 15485b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1549951361f9SAl Viro nd->root.mnt = NULL; 15508b61e74fSAl Viro rcu_read_unlock(); 1551951361f9SAl Viro } 155215439726SAl Viro while (unlikely(nd->depth)) 155315439726SAl Viro put_link(nd); 1554951361f9SAl Viro } 1555951361f9SAl Viro 1556d63ff28fSAl Viro static int pick_link(struct nameidata *nd, struct path *link) 1557d63ff28fSAl Viro { 1558626de996SAl Viro int error; 15591cf2665bSAl Viro struct saved *last; 1560756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1561626de996SAl Viro path_to_nameidata(link, nd); 1562626de996SAl Viro return -ELOOP; 1563626de996SAl Viro } 1564d63ff28fSAl Viro if (nd->flags & LOOKUP_RCU) { 1565d63ff28fSAl Viro if (unlikely(nd->path.mnt != link->mnt || 1566d63ff28fSAl Viro unlazy_walk(nd, link->dentry))) { 1567d63ff28fSAl Viro return -ECHILD; 1568d63ff28fSAl Viro } 1569d63ff28fSAl Viro } 1570cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1571cd179f44SAl Viro mntget(link->mnt); 1572626de996SAl Viro error = nd_alloc_stack(nd); 1573626de996SAl Viro if (unlikely(error)) { 1574cd179f44SAl Viro path_put(link); 1575626de996SAl Viro return error; 1576626de996SAl Viro } 1577626de996SAl Viro 15781cf2665bSAl Viro last = nd->stack + nd->depth; 15791cf2665bSAl Viro last->link = *link; 1580d63ff28fSAl Viro return 1; 1581d63ff28fSAl Viro } 1582d63ff28fSAl Viro 15833ddcd056SLinus Torvalds /* 15843ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 15853ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 15863ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 15873ddcd056SLinus Torvalds * for the common case. 15883ddcd056SLinus Torvalds */ 1589d63ff28fSAl Viro static inline int should_follow_link(struct nameidata *nd, struct path *link, int follow) 15903ddcd056SLinus Torvalds { 1591d63ff28fSAl Viro if (likely(!d_is_symlink(link->dentry))) 1592d63ff28fSAl Viro return 0; 1593d63ff28fSAl Viro if (!follow) 1594d63ff28fSAl Viro return 0; 1595d63ff28fSAl Viro return pick_link(nd, link); 15963ddcd056SLinus Torvalds } 15973ddcd056SLinus Torvalds 15984693a547SAl Viro enum {WALK_GET = 1, WALK_PUT = 2}; 15994693a547SAl Viro 16004693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1601ce57dfc1SAl Viro { 1602caa85634SAl Viro struct path path; 1603ce57dfc1SAl Viro struct inode *inode; 1604ce57dfc1SAl Viro int err; 1605ce57dfc1SAl Viro /* 1606ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1607ce57dfc1SAl Viro * to be able to know about the current root directory and 1608ce57dfc1SAl Viro * parent relationships. 1609ce57dfc1SAl Viro */ 16104693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 16114693a547SAl Viro err = handle_dots(nd, nd->last_type); 16124693a547SAl Viro if (flags & WALK_PUT) 16134693a547SAl Viro put_link(nd); 16144693a547SAl Viro return err; 16154693a547SAl Viro } 1616caa85634SAl Viro err = lookup_fast(nd, &path, &inode); 1617ce57dfc1SAl Viro if (unlikely(err)) { 1618697f514dSMiklos Szeredi if (err < 0) 1619f0a9ba70SAl Viro return err; 1620697f514dSMiklos Szeredi 1621caa85634SAl Viro err = lookup_slow(nd, &path); 1622697f514dSMiklos Szeredi if (err < 0) 1623f0a9ba70SAl Viro return err; 1624697f514dSMiklos Szeredi 1625caa85634SAl Viro inode = path.dentry->d_inode; 1626697f514dSMiklos Szeredi err = -ENOENT; 1627caa85634SAl Viro if (d_is_negative(path.dentry)) 1628697f514dSMiklos Szeredi goto out_path_put; 1629766c4cbfSAl Viro } 1630697f514dSMiklos Szeredi 16314693a547SAl Viro if (flags & WALK_PUT) 16324693a547SAl Viro put_link(nd); 1633d63ff28fSAl Viro err = should_follow_link(nd, &path, flags & WALK_GET); 1634d63ff28fSAl Viro if (unlikely(err)) 1635d63ff28fSAl Viro return err; 1636caa85634SAl Viro path_to_nameidata(&path, nd); 1637ce57dfc1SAl Viro nd->inode = inode; 1638ce57dfc1SAl Viro return 0; 1639697f514dSMiklos Szeredi 1640697f514dSMiklos Szeredi out_path_put: 1641caa85634SAl Viro path_to_nameidata(&path, nd); 1642697f514dSMiklos Szeredi return err; 1643ce57dfc1SAl Viro } 1644ce57dfc1SAl Viro 16451da177e4SLinus Torvalds /* 1646bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1647bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1648bfcfaa77SLinus Torvalds * 1649bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1650bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1651bfcfaa77SLinus Torvalds * fast. 1652bfcfaa77SLinus Torvalds * 1653bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1654bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1655bfcfaa77SLinus Torvalds * crossing operation. 1656bfcfaa77SLinus Torvalds * 1657bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1658bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1659bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1660bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1661bfcfaa77SLinus Torvalds */ 1662bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1663bfcfaa77SLinus Torvalds 1664f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1665bfcfaa77SLinus Torvalds 1666f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1667bfcfaa77SLinus Torvalds 1668bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1669bfcfaa77SLinus Torvalds { 167099d263d4SLinus Torvalds return hash_64(hash, 32); 1671bfcfaa77SLinus Torvalds } 1672bfcfaa77SLinus Torvalds 1673bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1674bfcfaa77SLinus Torvalds 1675bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1676bfcfaa77SLinus Torvalds 1677bfcfaa77SLinus Torvalds #endif 1678bfcfaa77SLinus Torvalds 1679bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1680bfcfaa77SLinus Torvalds { 1681bfcfaa77SLinus Torvalds unsigned long a, mask; 1682bfcfaa77SLinus Torvalds unsigned long hash = 0; 1683bfcfaa77SLinus Torvalds 1684bfcfaa77SLinus Torvalds for (;;) { 1685e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1686bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1687bfcfaa77SLinus Torvalds break; 1688bfcfaa77SLinus Torvalds hash += a; 1689f132c5beSAl Viro hash *= 9; 1690bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1691bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1692bfcfaa77SLinus Torvalds if (!len) 1693bfcfaa77SLinus Torvalds goto done; 1694bfcfaa77SLinus Torvalds } 1695a5c21dceSWill Deacon mask = bytemask_from_count(len); 1696bfcfaa77SLinus Torvalds hash += mask & a; 1697bfcfaa77SLinus Torvalds done: 1698bfcfaa77SLinus Torvalds return fold_hash(hash); 1699bfcfaa77SLinus Torvalds } 1700bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1701bfcfaa77SLinus Torvalds 1702bfcfaa77SLinus Torvalds /* 1703bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1704d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1705bfcfaa77SLinus Torvalds */ 1706d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1707bfcfaa77SLinus Torvalds { 170836126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 170936126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1710bfcfaa77SLinus Torvalds 1711bfcfaa77SLinus Torvalds hash = a = 0; 1712bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1713bfcfaa77SLinus Torvalds do { 1714bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1715bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1716e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 171736126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 171836126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1719bfcfaa77SLinus Torvalds 172036126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 172136126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 172236126f8fSLinus Torvalds 172336126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 172436126f8fSLinus Torvalds 172536126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 17269226b5b4SLinus Torvalds len += find_zero(mask); 1727d6bb3e90SLinus Torvalds return hashlen_create(fold_hash(hash), len); 1728bfcfaa77SLinus Torvalds } 1729bfcfaa77SLinus Torvalds 1730bfcfaa77SLinus Torvalds #else 1731bfcfaa77SLinus Torvalds 17320145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 17330145acc2SLinus Torvalds { 17340145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 17350145acc2SLinus Torvalds while (len--) 17360145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 17370145acc2SLinus Torvalds return end_name_hash(hash); 17380145acc2SLinus Torvalds } 1739ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 17400145acc2SLinus Torvalds 17413ddcd056SLinus Torvalds /* 1742200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1743200e9ef7SLinus Torvalds * one character. 1744200e9ef7SLinus Torvalds */ 1745d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1746200e9ef7SLinus Torvalds { 1747200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1748200e9ef7SLinus Torvalds unsigned long len = 0, c; 1749200e9ef7SLinus Torvalds 1750200e9ef7SLinus Torvalds c = (unsigned char)*name; 1751200e9ef7SLinus Torvalds do { 1752200e9ef7SLinus Torvalds len++; 1753200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1754200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1755200e9ef7SLinus Torvalds } while (c && c != '/'); 1756d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 1757200e9ef7SLinus Torvalds } 1758200e9ef7SLinus Torvalds 1759bfcfaa77SLinus Torvalds #endif 1760bfcfaa77SLinus Torvalds 1761200e9ef7SLinus Torvalds /* 17621da177e4SLinus Torvalds * Name resolution. 1763ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1764ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 17651da177e4SLinus Torvalds * 1766ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1767ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 17681da177e4SLinus Torvalds */ 17696de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 17701da177e4SLinus Torvalds { 17711da177e4SLinus Torvalds int err; 17721da177e4SLinus Torvalds 17731da177e4SLinus Torvalds while (*name=='/') 17741da177e4SLinus Torvalds name++; 17751da177e4SLinus Torvalds if (!*name) 17769e18f10aSAl Viro return 0; 17771da177e4SLinus Torvalds 17781da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 17791da177e4SLinus Torvalds for(;;) { 1780d6bb3e90SLinus Torvalds u64 hash_len; 1781fe479a58SAl Viro int type; 17821da177e4SLinus Torvalds 178352094c8aSAl Viro err = may_lookup(nd); 17841da177e4SLinus Torvalds if (err) 17851da177e4SLinus Torvalds break; 17861da177e4SLinus Torvalds 1787d6bb3e90SLinus Torvalds hash_len = hash_name(name); 17881da177e4SLinus Torvalds 1789fe479a58SAl Viro type = LAST_NORM; 1790d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 1791fe479a58SAl Viro case 2: 1792200e9ef7SLinus Torvalds if (name[1] == '.') { 1793fe479a58SAl Viro type = LAST_DOTDOT; 179416c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 179516c2cd71SAl Viro } 1796fe479a58SAl Viro break; 1797fe479a58SAl Viro case 1: 1798fe479a58SAl Viro type = LAST_DOT; 1799fe479a58SAl Viro } 18005a202bcdSAl Viro if (likely(type == LAST_NORM)) { 18015a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 180216c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 18035a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 1804a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 1805da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 18065a202bcdSAl Viro if (err < 0) 18075a202bcdSAl Viro break; 1808d6bb3e90SLinus Torvalds hash_len = this.hash_len; 1809d6bb3e90SLinus Torvalds name = this.name; 18105a202bcdSAl Viro } 18115a202bcdSAl Viro } 1812fe479a58SAl Viro 1813d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 1814d6bb3e90SLinus Torvalds nd->last.name = name; 18155f4a6a69SAl Viro nd->last_type = type; 18165f4a6a69SAl Viro 1817d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 1818d6bb3e90SLinus Torvalds if (!*name) 1819bdf6cbf1SAl Viro goto OK; 1820200e9ef7SLinus Torvalds /* 1821200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1822200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1823200e9ef7SLinus Torvalds */ 1824200e9ef7SLinus Torvalds do { 1825d6bb3e90SLinus Torvalds name++; 1826d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 18278620c238SAl Viro if (unlikely(!*name)) { 18288620c238SAl Viro OK: 18298620c238SAl Viro /* called from path_init(), done */ 18308620c238SAl Viro if (!nd->depth) 18318620c238SAl Viro return 0; 18328620c238SAl Viro name = nd->stack[nd->depth - 1].name; 18338620c238SAl Viro /* called from trailing_symlink(), done */ 18348620c238SAl Viro if (!name) 18358620c238SAl Viro return 0; 18368620c238SAl Viro /* last component of nested symlink */ 18374693a547SAl Viro err = walk_component(nd, WALK_GET | WALK_PUT); 18388620c238SAl Viro } else { 18394693a547SAl Viro err = walk_component(nd, WALK_GET); 18408620c238SAl Viro } 1841ce57dfc1SAl Viro if (err < 0) 1842f0a9ba70SAl Viro break; 1843fe479a58SAl Viro 1844ce57dfc1SAl Viro if (err) { 1845626de996SAl Viro const char *s = get_link(nd); 18465a460275SAl Viro 1847172a39a0SAl Viro if (unlikely(IS_ERR(s))) { 1848172a39a0SAl Viro err = PTR_ERR(s); 18491bc4b813SAl Viro break; 1850172a39a0SAl Viro } 1851172a39a0SAl Viro err = 0; 185212b09578SAl Viro if (unlikely(!s)) { 185312b09578SAl Viro /* jumped */ 1854b9ff4429SAl Viro put_link(nd); 185512b09578SAl Viro } else { 1856071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 185732cd7468SAl Viro name = s; 18589e18f10aSAl Viro continue; 185948c8b0c5SAl Viro } 186031e6b01fSNick Piggin } 186144b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 18623ddcd056SLinus Torvalds err = -ENOTDIR; 18633ddcd056SLinus Torvalds break; 18645f4a6a69SAl Viro } 1865ce57dfc1SAl Viro } 1866951361f9SAl Viro terminate_walk(nd); 18671da177e4SLinus Torvalds return err; 186807681481SAl Viro } 18691da177e4SLinus Torvalds 18706e8a1f87SAl Viro static int path_init(int dfd, const struct filename *name, unsigned int flags, 18715e53084dSAl Viro struct nameidata *nd) 187231e6b01fSNick Piggin { 187331e6b01fSNick Piggin int retval = 0; 1874fd2f7cb5SAl Viro const char *s = name->name; 187531e6b01fSNick Piggin 187631e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 1877980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 187831e6b01fSNick Piggin nd->depth = 0; 18795e53084dSAl Viro nd->base = NULL; 18805b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 1881b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 1882b18825a7SDavid Howells struct inode *inode = root->d_inode; 1883fd2f7cb5SAl Viro if (*s) { 188444b1d530SMiklos Szeredi if (!d_can_lookup(root)) 18855b6ca027SAl Viro return -ENOTDIR; 18865b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 18875b6ca027SAl Viro if (retval) 18885b6ca027SAl Viro return retval; 188973d049a4SAl Viro } 18905b6ca027SAl Viro nd->path = nd->root; 18915b6ca027SAl Viro nd->inode = inode; 18925b6ca027SAl Viro if (flags & LOOKUP_RCU) { 18938b61e74fSAl Viro rcu_read_lock(); 18945b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 189548a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 18965b6ca027SAl Viro } else { 18975b6ca027SAl Viro path_get(&nd->path); 18985b6ca027SAl Viro } 1899d465887fSAl Viro goto done; 19005b6ca027SAl Viro } 19015b6ca027SAl Viro 190231e6b01fSNick Piggin nd->root.mnt = NULL; 190331e6b01fSNick Piggin 190448a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 1905fd2f7cb5SAl Viro if (*s == '/') { 1906e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 19078b61e74fSAl Viro rcu_read_lock(); 19087bd88377SAl Viro nd->seq = set_root_rcu(nd); 1909e41f7d4eSAl Viro } else { 1910e41f7d4eSAl Viro set_root(nd); 1911e41f7d4eSAl Viro path_get(&nd->root); 1912e41f7d4eSAl Viro } 191331e6b01fSNick Piggin nd->path = nd->root; 191431e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1915e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 191631e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1917c28cc364SNick Piggin unsigned seq; 191831e6b01fSNick Piggin 19198b61e74fSAl Viro rcu_read_lock(); 192031e6b01fSNick Piggin 1921c28cc364SNick Piggin do { 1922c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 192331e6b01fSNick Piggin nd->path = fs->pwd; 1924c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1925c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1926e41f7d4eSAl Viro } else { 1927e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1928e41f7d4eSAl Viro } 192931e6b01fSNick Piggin } else { 1930582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 19312903ff01SAl Viro struct fd f = fdget_raw(dfd); 193231e6b01fSNick Piggin struct dentry *dentry; 193331e6b01fSNick Piggin 19342903ff01SAl Viro if (!f.file) 19352903ff01SAl Viro return -EBADF; 193631e6b01fSNick Piggin 19372903ff01SAl Viro dentry = f.file->f_path.dentry; 193831e6b01fSNick Piggin 1939fd2f7cb5SAl Viro if (*s) { 194044b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 19412903ff01SAl Viro fdput(f); 19422903ff01SAl Viro return -ENOTDIR; 1943f52e0c11SAl Viro } 19442903ff01SAl Viro } 19452903ff01SAl Viro 19462903ff01SAl Viro nd->path = f.file->f_path; 1947e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 19489c225f26SLinus Torvalds if (f.flags & FDPUT_FPUT) 19495e53084dSAl Viro nd->base = f.file; 1950c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 19518b61e74fSAl Viro rcu_read_lock(); 19525590ff0dSUlrich Drepper } else { 19532903ff01SAl Viro path_get(&nd->path); 19542903ff01SAl Viro fdput(f); 19551da177e4SLinus Torvalds } 1956e41f7d4eSAl Viro } 1957e41f7d4eSAl Viro 195831e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 19594023bfc9SAl Viro if (!(flags & LOOKUP_RCU)) 1960d465887fSAl Viro goto done; 19614023bfc9SAl Viro if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) 1962d465887fSAl Viro goto done; 19634023bfc9SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 19644023bfc9SAl Viro nd->root.mnt = NULL; 19654023bfc9SAl Viro rcu_read_unlock(); 19664023bfc9SAl Viro return -ECHILD; 1967d465887fSAl Viro done: 1968756daf26SNeilBrown nd->total_link_count = 0; 1969dc7af8dcSAl Viro return link_path_walk(s, nd); 19709b4a9b14SAl Viro } 19719b4a9b14SAl Viro 1972893b7775SAl Viro static void path_cleanup(struct nameidata *nd) 1973893b7775SAl Viro { 1974893b7775SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 1975893b7775SAl Viro path_put(&nd->root); 1976893b7775SAl Viro nd->root.mnt = NULL; 1977893b7775SAl Viro } 1978893b7775SAl Viro if (unlikely(nd->base)) 1979893b7775SAl Viro fput(nd->base); 19809b4a9b14SAl Viro } 19819b4a9b14SAl Viro 19821d8e03d3SAl Viro static int trailing_symlink(struct nameidata *nd) 198395fa25d9SAl Viro { 198495fa25d9SAl Viro const char *s; 1985fec2fa24SAl Viro int error = may_follow_link(nd); 198695fa25d9SAl Viro if (unlikely(error)) 198795fa25d9SAl Viro return error; 198895fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 1989fab51e8aSAl Viro nd->stack[0].name = NULL; 19903b2e7f75SAl Viro s = get_link(nd); 19911bc4b813SAl Viro if (unlikely(IS_ERR(s))) { 19921bc4b813SAl Viro terminate_walk(nd); 199395fa25d9SAl Viro return PTR_ERR(s); 19941bc4b813SAl Viro } 19959ea57b72SAl Viro if (unlikely(!s)) 199695fa25d9SAl Viro return 0; 19978eff733aSAl Viro return link_path_walk(s, nd); 199895fa25d9SAl Viro } 199995fa25d9SAl Viro 2000caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2001bd92d7feSAl Viro { 2002f0a9ba70SAl Viro int err; 2003bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2004bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2005bd92d7feSAl Viro 2006bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 20074693a547SAl Viro err = walk_component(nd, 20084693a547SAl Viro nd->flags & LOOKUP_FOLLOW 20094693a547SAl Viro ? nd->depth 20104693a547SAl Viro ? WALK_PUT | WALK_GET 20114693a547SAl Viro : WALK_GET 20124693a547SAl Viro : 0); 2013f0a9ba70SAl Viro if (err < 0) 2014f0a9ba70SAl Viro terminate_walk(nd); 2015f0a9ba70SAl Viro return err; 2016bd92d7feSAl Viro } 2017bd92d7feSAl Viro 20189b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 20195eb6b495SAl Viro static int path_lookupat(int dfd, const struct filename *name, 20209b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 20219b4a9b14SAl Viro { 2022bd92d7feSAl Viro int err; 202331e6b01fSNick Piggin 202431e6b01fSNick Piggin /* 202531e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 202631e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 202731e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 202831e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 202931e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 203031e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 203131e6b01fSNick Piggin * analogue, foo_rcu(). 203231e6b01fSNick Piggin * 203331e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 203431e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 203531e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 203631e6b01fSNick Piggin * be able to complete). 203731e6b01fSNick Piggin */ 20386e8a1f87SAl Viro err = path_init(dfd, name, flags, nd); 2039bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 2040191d7f73SAl Viro while ((err = lookup_last(nd)) > 0) { 20411d8e03d3SAl Viro err = trailing_symlink(nd); 20426d7b5aaeSAl Viro if (err) 20436d7b5aaeSAl Viro break; 2044bd92d7feSAl Viro } 2045bd92d7feSAl Viro } 2046ee0827cdSAl Viro 20479f1fafeeSAl Viro if (!err) 20489f1fafeeSAl Viro err = complete_walk(nd); 2049bd92d7feSAl Viro 2050bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 205144b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 2052bd92d7feSAl Viro path_put(&nd->path); 2053bd23a539SAl Viro err = -ENOTDIR; 2054bd92d7feSAl Viro } 2055bd92d7feSAl Viro } 205616c2cd71SAl Viro 2057893b7775SAl Viro path_cleanup(nd); 2058bd92d7feSAl Viro return err; 205931e6b01fSNick Piggin } 206031e6b01fSNick Piggin 2061873f1eedSJeff Layton static int filename_lookup(int dfd, struct filename *name, 2062873f1eedSJeff Layton unsigned int flags, struct nameidata *nd) 2063873f1eedSJeff Layton { 2064894bc8c4SAl Viro int retval; 2065756daf26SNeilBrown struct nameidata *saved_nd = set_nameidata(nd); 2066894bc8c4SAl Viro 2067894bc8c4SAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 2068873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 20695eb6b495SAl Viro retval = path_lookupat(dfd, name, flags, nd); 2070873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 20715eb6b495SAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 2072873f1eedSJeff Layton 2073873f1eedSJeff Layton if (likely(!retval)) 2074adb5c247SJeff Layton audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); 2075756daf26SNeilBrown restore_nameidata(saved_nd); 2076873f1eedSJeff Layton return retval; 2077873f1eedSJeff Layton } 2078873f1eedSJeff Layton 207979714f72SAl Viro /* does lookup, returns the object with parent locked */ 208079714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 20815590ff0dSUlrich Drepper { 208251689104SPaul Moore struct filename *filename = getname_kernel(name); 208379714f72SAl Viro struct nameidata nd; 208479714f72SAl Viro struct dentry *d; 208551689104SPaul Moore int err; 208651689104SPaul Moore 208751689104SPaul Moore if (IS_ERR(filename)) 208851689104SPaul Moore return ERR_CAST(filename); 208951689104SPaul Moore 209051689104SPaul Moore err = filename_lookup(AT_FDCWD, filename, LOOKUP_PARENT, &nd); 209151689104SPaul Moore if (err) { 209251689104SPaul Moore d = ERR_PTR(err); 209351689104SPaul Moore goto out; 209451689104SPaul Moore } 209579714f72SAl Viro if (nd.last_type != LAST_NORM) { 209679714f72SAl Viro path_put(&nd.path); 209751689104SPaul Moore d = ERR_PTR(-EINVAL); 209851689104SPaul Moore goto out; 209979714f72SAl Viro } 210079714f72SAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 21011e0ea001SAl Viro d = __lookup_hash(&nd.last, nd.path.dentry, 0); 210279714f72SAl Viro if (IS_ERR(d)) { 210379714f72SAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 210479714f72SAl Viro path_put(&nd.path); 210551689104SPaul Moore goto out; 210679714f72SAl Viro } 210779714f72SAl Viro *path = nd.path; 210851689104SPaul Moore out: 210951689104SPaul Moore putname(filename); 211079714f72SAl Viro return d; 21115590ff0dSUlrich Drepper } 21125590ff0dSUlrich Drepper 2113d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2114d1811465SAl Viro { 2115d1811465SAl Viro struct nameidata nd; 211674eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 211774eb8cc5SAl Viro int res = PTR_ERR(filename); 211874eb8cc5SAl Viro 211974eb8cc5SAl Viro if (!IS_ERR(filename)) { 212074eb8cc5SAl Viro res = filename_lookup(AT_FDCWD, filename, flags, &nd); 212174eb8cc5SAl Viro putname(filename); 2122d1811465SAl Viro if (!res) 2123d1811465SAl Viro *path = nd.path; 212474eb8cc5SAl Viro } 2125d1811465SAl Viro return res; 2126d1811465SAl Viro } 21274d359507SAl Viro EXPORT_SYMBOL(kern_path); 2128d1811465SAl Viro 212916f18200SJosef 'Jeff' Sipek /** 213016f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 213116f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 213216f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 213316f18200SJosef 'Jeff' Sipek * @name: pointer to file name 213416f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2135e0a01249SAl Viro * @path: pointer to struct path to fill 213616f18200SJosef 'Jeff' Sipek */ 213716f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 213816f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2139e0a01249SAl Viro struct path *path) 214016f18200SJosef 'Jeff' Sipek { 214174eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 214274eb8cc5SAl Viro int err = PTR_ERR(filename); 214374eb8cc5SAl Viro 214474eb8cc5SAl Viro BUG_ON(flags & LOOKUP_PARENT); 214574eb8cc5SAl Viro 214674eb8cc5SAl Viro /* the first argument of filename_lookup() is ignored with LOOKUP_ROOT */ 214774eb8cc5SAl Viro if (!IS_ERR(filename)) { 2148e0a01249SAl Viro struct nameidata nd; 2149e0a01249SAl Viro nd.root.dentry = dentry; 2150e0a01249SAl Viro nd.root.mnt = mnt; 215174eb8cc5SAl Viro err = filename_lookup(AT_FDCWD, filename, 215274eb8cc5SAl Viro flags | LOOKUP_ROOT, &nd); 2153e0a01249SAl Viro if (!err) 2154e0a01249SAl Viro *path = nd.path; 215574eb8cc5SAl Viro putname(filename); 215674eb8cc5SAl Viro } 2157e0a01249SAl Viro return err; 215816f18200SJosef 'Jeff' Sipek } 21594d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 216016f18200SJosef 'Jeff' Sipek 2161eead1911SChristoph Hellwig /** 2162a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2163eead1911SChristoph Hellwig * @name: pathname component to lookup 2164eead1911SChristoph Hellwig * @base: base directory to lookup from 2165eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2166eead1911SChristoph Hellwig * 2167a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 21689e7543e9SAl Viro * not be called by generic code. 2169eead1911SChristoph Hellwig */ 2170057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2171057f6c01SJames Morris { 2172057f6c01SJames Morris struct qstr this; 21736a96ba54SAl Viro unsigned int c; 2174cda309deSMiklos Szeredi int err; 2175057f6c01SJames Morris 21762f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 21772f9092e1SDavid Woodhouse 21786a96ba54SAl Viro this.name = name; 21796a96ba54SAl Viro this.len = len; 21800145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 21816a96ba54SAl Viro if (!len) 21826a96ba54SAl Viro return ERR_PTR(-EACCES); 21836a96ba54SAl Viro 218421d8a15aSAl Viro if (unlikely(name[0] == '.')) { 218521d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 218621d8a15aSAl Viro return ERR_PTR(-EACCES); 218721d8a15aSAl Viro } 218821d8a15aSAl Viro 21896a96ba54SAl Viro while (len--) { 21906a96ba54SAl Viro c = *(const unsigned char *)name++; 21916a96ba54SAl Viro if (c == '/' || c == '\0') 21926a96ba54SAl Viro return ERR_PTR(-EACCES); 21936a96ba54SAl Viro } 21945a202bcdSAl Viro /* 21955a202bcdSAl Viro * See if the low-level filesystem might want 21965a202bcdSAl Viro * to use its own hash.. 21975a202bcdSAl Viro */ 21985a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2199da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 22005a202bcdSAl Viro if (err < 0) 22015a202bcdSAl Viro return ERR_PTR(err); 22025a202bcdSAl Viro } 2203eead1911SChristoph Hellwig 2204cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2205cda309deSMiklos Szeredi if (err) 2206cda309deSMiklos Szeredi return ERR_PTR(err); 2207cda309deSMiklos Szeredi 220872bd866aSAl Viro return __lookup_hash(&this, base, 0); 2209057f6c01SJames Morris } 22104d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2211057f6c01SJames Morris 22121fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 22131fa1e7f6SAndy Whitcroft struct path *path, int *empty) 22141da177e4SLinus Torvalds { 22152d8f3038SAl Viro struct nameidata nd; 221691a27b2aSJeff Layton struct filename *tmp = getname_flags(name, flags, empty); 22171da177e4SLinus Torvalds int err = PTR_ERR(tmp); 22181da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 22192d8f3038SAl Viro 22202d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 22212d8f3038SAl Viro 2222873f1eedSJeff Layton err = filename_lookup(dfd, tmp, flags, &nd); 22231da177e4SLinus Torvalds putname(tmp); 22242d8f3038SAl Viro if (!err) 22252d8f3038SAl Viro *path = nd.path; 22261da177e4SLinus Torvalds } 22271da177e4SLinus Torvalds return err; 22281da177e4SLinus Torvalds } 22291da177e4SLinus Torvalds 22301fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 22311fa1e7f6SAndy Whitcroft struct path *path) 22321fa1e7f6SAndy Whitcroft { 2233f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 22341fa1e7f6SAndy Whitcroft } 22354d359507SAl Viro EXPORT_SYMBOL(user_path_at); 22361fa1e7f6SAndy Whitcroft 2237873f1eedSJeff Layton /* 2238873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2239873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2240873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2241873f1eedSJeff Layton * path-walking is complete. 2242873f1eedSJeff Layton */ 224391a27b2aSJeff Layton static struct filename * 2244f5beed75SAl Viro user_path_parent(int dfd, const char __user *path, 2245f5beed75SAl Viro struct path *parent, 2246f5beed75SAl Viro struct qstr *last, 2247f5beed75SAl Viro int *type, 22489e790bd6SJeff Layton unsigned int flags) 22492ad94ae6SAl Viro { 2250f5beed75SAl Viro struct nameidata nd; 225191a27b2aSJeff Layton struct filename *s = getname(path); 22522ad94ae6SAl Viro int error; 22532ad94ae6SAl Viro 22549e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 22559e790bd6SJeff Layton flags &= LOOKUP_REVAL; 22569e790bd6SJeff Layton 22572ad94ae6SAl Viro if (IS_ERR(s)) 225891a27b2aSJeff Layton return s; 22592ad94ae6SAl Viro 2260f5beed75SAl Viro error = filename_lookup(dfd, s, flags | LOOKUP_PARENT, &nd); 226191a27b2aSJeff Layton if (error) { 22622ad94ae6SAl Viro putname(s); 226391a27b2aSJeff Layton return ERR_PTR(error); 226491a27b2aSJeff Layton } 2265f5beed75SAl Viro *parent = nd.path; 2266f5beed75SAl Viro *last = nd.last; 2267f5beed75SAl Viro *type = nd.last_type; 22682ad94ae6SAl Viro 226991a27b2aSJeff Layton return s; 22702ad94ae6SAl Viro } 22712ad94ae6SAl Viro 22728033426eSJeff Layton /** 2273197df04cSAl Viro * mountpoint_last - look up last component for umount 22748033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 22758033426eSJeff Layton * @path: pointer to container for result 22768033426eSJeff Layton * 22778033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 22788033426eSJeff Layton * need to resolve the path without doing any revalidation. 22798033426eSJeff Layton * 22808033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 22818033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 22828033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 22838033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 22848033426eSJeff Layton * bogus and it doesn't exist. 22858033426eSJeff Layton * 22868033426eSJeff Layton * Returns: 22878033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 22888033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 22898033426eSJeff Layton * put in this case. 22908033426eSJeff Layton * 22918033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 22928033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 22938033426eSJeff Layton * The nd->path reference will also be put. 22948033426eSJeff Layton * 22958033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 22968033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 22978033426eSJeff Layton * to the link, and nd->path will *not* be put. 22988033426eSJeff Layton */ 22998033426eSJeff Layton static int 2300197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 23018033426eSJeff Layton { 23028033426eSJeff Layton int error = 0; 23038033426eSJeff Layton struct dentry *dentry; 23048033426eSJeff Layton struct dentry *dir = nd->path.dentry; 23058033426eSJeff Layton 230635759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 230735759521SAl Viro if (nd->flags & LOOKUP_RCU) { 230835759521SAl Viro if (unlazy_walk(nd, NULL)) { 23098033426eSJeff Layton error = -ECHILD; 231035759521SAl Viro goto out; 231135759521SAl Viro } 23128033426eSJeff Layton } 23138033426eSJeff Layton 23148033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 23158033426eSJeff Layton 23168033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 23178033426eSJeff Layton error = handle_dots(nd, nd->last_type); 231835759521SAl Viro if (error) 231935759521SAl Viro goto out; 23208033426eSJeff Layton dentry = dget(nd->path.dentry); 232135759521SAl Viro goto done; 23228033426eSJeff Layton } 23238033426eSJeff Layton 23248033426eSJeff Layton mutex_lock(&dir->d_inode->i_mutex); 23258033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 23268033426eSJeff Layton if (!dentry) { 23278033426eSJeff Layton /* 23288033426eSJeff Layton * No cached dentry. Mounted dentries are pinned in the cache, 23298033426eSJeff Layton * so that means that this dentry is probably a symlink or the 23308033426eSJeff Layton * path doesn't actually point to a mounted dentry. 23318033426eSJeff Layton */ 23328033426eSJeff Layton dentry = d_alloc(dir, &nd->last); 23338033426eSJeff Layton if (!dentry) { 23348033426eSJeff Layton error = -ENOMEM; 2335bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 233635759521SAl Viro goto out; 23378033426eSJeff Layton } 233835759521SAl Viro dentry = lookup_real(dir->d_inode, dentry, nd->flags); 233935759521SAl Viro error = PTR_ERR(dentry); 2340bcceeebaSDave Jones if (IS_ERR(dentry)) { 2341bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 234235759521SAl Viro goto out; 23438033426eSJeff Layton } 2344bcceeebaSDave Jones } 23458033426eSJeff Layton mutex_unlock(&dir->d_inode->i_mutex); 23468033426eSJeff Layton 234735759521SAl Viro done: 2348698934dfSDavid Howells if (d_is_negative(dentry)) { 23498033426eSJeff Layton error = -ENOENT; 23508033426eSJeff Layton dput(dentry); 235135759521SAl Viro goto out; 235235759521SAl Viro } 2353191d7f73SAl Viro if (nd->depth) 2354191d7f73SAl Viro put_link(nd); 23558033426eSJeff Layton path->dentry = dentry; 2356295dc39dSVasily Averin path->mnt = nd->path.mnt; 2357d63ff28fSAl Viro error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW); 2358d63ff28fSAl Viro if (unlikely(error)) { 2359d63ff28fSAl Viro if (error < 0) 2360d63ff28fSAl Viro goto out; 2361d63ff28fSAl Viro return error; 2362caa85634SAl Viro } 2363295dc39dSVasily Averin mntget(path->mnt); 23648033426eSJeff Layton follow_mount(path); 236535759521SAl Viro error = 0; 236635759521SAl Viro out: 23678033426eSJeff Layton terminate_walk(nd); 23688033426eSJeff Layton return error; 23698033426eSJeff Layton } 23708033426eSJeff Layton 23718033426eSJeff Layton /** 2372197df04cSAl Viro * path_mountpoint - look up a path to be umounted 23738033426eSJeff Layton * @dfd: directory file descriptor to start walk from 23748033426eSJeff Layton * @name: full pathname to walk 2375606d6fe3SRandy Dunlap * @path: pointer to container for result 23768033426eSJeff Layton * @flags: lookup flags 23778033426eSJeff Layton * 23788033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2379606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 23808033426eSJeff Layton */ 23818033426eSJeff Layton static int 2382668696dcSAl Viro path_mountpoint(int dfd, const struct filename *name, struct path *path, 238346afd6f6SAl Viro struct nameidata *nd, unsigned int flags) 23848033426eSJeff Layton { 238546afd6f6SAl Viro int err = path_init(dfd, name, flags, nd); 23868033426eSJeff Layton if (unlikely(err)) 2387115cbfdcSAl Viro goto out; 23888033426eSJeff Layton 2389191d7f73SAl Viro while ((err = mountpoint_last(nd, path)) > 0) { 23901d8e03d3SAl Viro err = trailing_symlink(nd); 23918033426eSJeff Layton if (err) 23928033426eSJeff Layton break; 23938033426eSJeff Layton } 23948033426eSJeff Layton out: 239546afd6f6SAl Viro path_cleanup(nd); 23968033426eSJeff Layton return err; 23978033426eSJeff Layton } 23988033426eSJeff Layton 23992d864651SAl Viro static int 2400668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 24012d864651SAl Viro unsigned int flags) 24022d864651SAl Viro { 2403756daf26SNeilBrown struct nameidata nd, *saved; 2404cbaab2dbSAl Viro int error; 2405668696dcSAl Viro if (IS_ERR(name)) 2406668696dcSAl Viro return PTR_ERR(name); 2407756daf26SNeilBrown saved = set_nameidata(&nd); 240846afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_RCU); 24092d864651SAl Viro if (unlikely(error == -ECHILD)) 241046afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags); 24112d864651SAl Viro if (unlikely(error == -ESTALE)) 241246afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_REVAL); 24132d864651SAl Viro if (likely(!error)) 2414668696dcSAl Viro audit_inode(name, path->dentry, 0); 2415756daf26SNeilBrown restore_nameidata(saved); 2416668696dcSAl Viro putname(name); 24172d864651SAl Viro return error; 24182d864651SAl Viro } 24192d864651SAl Viro 24208033426eSJeff Layton /** 2421197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 24228033426eSJeff Layton * @dfd: directory file descriptor 24238033426eSJeff Layton * @name: pathname from userland 24248033426eSJeff Layton * @flags: lookup flags 24258033426eSJeff Layton * @path: pointer to container to hold result 24268033426eSJeff Layton * 24278033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 24288033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 24298033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 24308033426eSJeff Layton * and avoid revalidating the last component. 24318033426eSJeff Layton * 24328033426eSJeff Layton * Returns 0 and populates "path" on success. 24338033426eSJeff Layton */ 24348033426eSJeff Layton int 2435197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 24368033426eSJeff Layton struct path *path) 24378033426eSJeff Layton { 2438cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 24398033426eSJeff Layton } 24408033426eSJeff Layton 24412d864651SAl Viro int 24422d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 24432d864651SAl Viro unsigned int flags) 24442d864651SAl Viro { 2445cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 24462d864651SAl Viro } 24472d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 24482d864651SAl Viro 2449cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 24501da177e4SLinus Torvalds { 24518e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2452da9592edSDavid Howells 24538e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 24541da177e4SLinus Torvalds return 0; 24558e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 24561da177e4SLinus Torvalds return 0; 245723adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 24581da177e4SLinus Torvalds } 2459cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 24601da177e4SLinus Torvalds 24611da177e4SLinus Torvalds /* 24621da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 24631da177e4SLinus Torvalds * whether the type of victim is right. 24641da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 24651da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 24661da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 24671da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 24681da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 24691da177e4SLinus Torvalds * a. be owner of dir, or 24701da177e4SLinus Torvalds * b. be owner of victim, or 24711da177e4SLinus Torvalds * c. have CAP_FOWNER capability 24721da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 24731da177e4SLinus Torvalds * links pointing to it. 24741da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 24751da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 24761da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 24771da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 24781da177e4SLinus Torvalds * nfs_async_unlink(). 24791da177e4SLinus Torvalds */ 2480b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 24811da177e4SLinus Torvalds { 2482b18825a7SDavid Howells struct inode *inode = victim->d_inode; 24831da177e4SLinus Torvalds int error; 24841da177e4SLinus Torvalds 2485b18825a7SDavid Howells if (d_is_negative(victim)) 24861da177e4SLinus Torvalds return -ENOENT; 2487b18825a7SDavid Howells BUG_ON(!inode); 24881da177e4SLinus Torvalds 24891da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 24904fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 24911da177e4SLinus Torvalds 2492f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 24931da177e4SLinus Torvalds if (error) 24941da177e4SLinus Torvalds return error; 24951da177e4SLinus Torvalds if (IS_APPEND(dir)) 24961da177e4SLinus Torvalds return -EPERM; 2497b18825a7SDavid Howells 2498b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2499b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 25001da177e4SLinus Torvalds return -EPERM; 25011da177e4SLinus Torvalds if (isdir) { 250244b1d530SMiklos Szeredi if (!d_is_dir(victim)) 25031da177e4SLinus Torvalds return -ENOTDIR; 25041da177e4SLinus Torvalds if (IS_ROOT(victim)) 25051da177e4SLinus Torvalds return -EBUSY; 250644b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 25071da177e4SLinus Torvalds return -EISDIR; 25081da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25091da177e4SLinus Torvalds return -ENOENT; 25101da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 25111da177e4SLinus Torvalds return -EBUSY; 25121da177e4SLinus Torvalds return 0; 25131da177e4SLinus Torvalds } 25141da177e4SLinus Torvalds 25151da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 25161da177e4SLinus Torvalds * dir. 25171da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 25181da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 25191da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 25201da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 25211da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 25221da177e4SLinus Torvalds */ 2523a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 25241da177e4SLinus Torvalds { 252514e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 25261da177e4SLinus Torvalds if (child->d_inode) 25271da177e4SLinus Torvalds return -EEXIST; 25281da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25291da177e4SLinus Torvalds return -ENOENT; 2530f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 25311da177e4SLinus Torvalds } 25321da177e4SLinus Torvalds 25331da177e4SLinus Torvalds /* 25341da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 25351da177e4SLinus Torvalds */ 25361da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 25371da177e4SLinus Torvalds { 25381da177e4SLinus Torvalds struct dentry *p; 25391da177e4SLinus Torvalds 25401da177e4SLinus Torvalds if (p1 == p2) { 2541f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 25421da177e4SLinus Torvalds return NULL; 25431da177e4SLinus Torvalds } 25441da177e4SLinus Torvalds 2545a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25461da177e4SLinus Torvalds 2547e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2548e2761a11SOGAWA Hirofumi if (p) { 2549f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2550f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 25511da177e4SLinus Torvalds return p; 25521da177e4SLinus Torvalds } 25531da177e4SLinus Torvalds 2554e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2555e2761a11SOGAWA Hirofumi if (p) { 2556f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2557f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 25581da177e4SLinus Torvalds return p; 25591da177e4SLinus Torvalds } 25601da177e4SLinus Torvalds 2561f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2562d1b72cc6SMiklos Szeredi mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); 25631da177e4SLinus Torvalds return NULL; 25641da177e4SLinus Torvalds } 25654d359507SAl Viro EXPORT_SYMBOL(lock_rename); 25661da177e4SLinus Torvalds 25671da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 25681da177e4SLinus Torvalds { 25691b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 25701da177e4SLinus Torvalds if (p1 != p2) { 25711b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2572a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25731da177e4SLinus Torvalds } 25741da177e4SLinus Torvalds } 25754d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 25761da177e4SLinus Torvalds 25774acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2578312b63fbSAl Viro bool want_excl) 25791da177e4SLinus Torvalds { 2580a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 25811da177e4SLinus Torvalds if (error) 25821da177e4SLinus Torvalds return error; 25831da177e4SLinus Torvalds 2584acfa4380SAl Viro if (!dir->i_op->create) 25851da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 25861da177e4SLinus Torvalds mode &= S_IALLUGO; 25871da177e4SLinus Torvalds mode |= S_IFREG; 25881da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 25891da177e4SLinus Torvalds if (error) 25901da177e4SLinus Torvalds return error; 2591312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2592a74574aaSStephen Smalley if (!error) 2593f38aa942SAmy Griffis fsnotify_create(dir, dentry); 25941da177e4SLinus Torvalds return error; 25951da177e4SLinus Torvalds } 25964d359507SAl Viro EXPORT_SYMBOL(vfs_create); 25971da177e4SLinus Torvalds 259873d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 25991da177e4SLinus Torvalds { 26003fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 26011da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 26021da177e4SLinus Torvalds int error; 26031da177e4SLinus Torvalds 2604bcda7652SAl Viro /* O_PATH? */ 2605bcda7652SAl Viro if (!acc_mode) 2606bcda7652SAl Viro return 0; 2607bcda7652SAl Viro 26081da177e4SLinus Torvalds if (!inode) 26091da177e4SLinus Torvalds return -ENOENT; 26101da177e4SLinus Torvalds 2611c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2612c8fe8f30SChristoph Hellwig case S_IFLNK: 26131da177e4SLinus Torvalds return -ELOOP; 2614c8fe8f30SChristoph Hellwig case S_IFDIR: 2615c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 26161da177e4SLinus Torvalds return -EISDIR; 2617c8fe8f30SChristoph Hellwig break; 2618c8fe8f30SChristoph Hellwig case S_IFBLK: 2619c8fe8f30SChristoph Hellwig case S_IFCHR: 26203fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 26211da177e4SLinus Torvalds return -EACCES; 2622c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2623c8fe8f30SChristoph Hellwig case S_IFIFO: 2624c8fe8f30SChristoph Hellwig case S_IFSOCK: 26251da177e4SLinus Torvalds flag &= ~O_TRUNC; 2626c8fe8f30SChristoph Hellwig break; 26274a3fd211SDave Hansen } 2628b41572e9SDave Hansen 26293fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2630b41572e9SDave Hansen if (error) 2631b41572e9SDave Hansen return error; 26326146f0d5SMimi Zohar 26331da177e4SLinus Torvalds /* 26341da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 26351da177e4SLinus Torvalds */ 26361da177e4SLinus Torvalds if (IS_APPEND(inode)) { 26378737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 26387715b521SAl Viro return -EPERM; 26391da177e4SLinus Torvalds if (flag & O_TRUNC) 26407715b521SAl Viro return -EPERM; 26411da177e4SLinus Torvalds } 26421da177e4SLinus Torvalds 26431da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 26442e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 26457715b521SAl Viro return -EPERM; 26461da177e4SLinus Torvalds 2647f3c7691eSJ. Bruce Fields return 0; 26487715b521SAl Viro } 26497715b521SAl Viro 2650e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 26517715b521SAl Viro { 2652e1181ee6SJeff Layton struct path *path = &filp->f_path; 26537715b521SAl Viro struct inode *inode = path->dentry->d_inode; 26547715b521SAl Viro int error = get_write_access(inode); 26551da177e4SLinus Torvalds if (error) 26567715b521SAl Viro return error; 26571da177e4SLinus Torvalds /* 26581da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 26591da177e4SLinus Torvalds */ 2660d7a06983SJeff Layton error = locks_verify_locked(filp); 2661be6d3e56SKentaro Takeda if (!error) 2662ea0d3ab2STetsuo Handa error = security_path_truncate(path); 26631da177e4SLinus Torvalds if (!error) { 26647715b521SAl Viro error = do_truncate(path->dentry, 0, 2665d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2666e1181ee6SJeff Layton filp); 26671da177e4SLinus Torvalds } 26681da177e4SLinus Torvalds put_write_access(inode); 2669acd0c935SMimi Zohar return error; 26701da177e4SLinus Torvalds } 26711da177e4SLinus Torvalds 2672d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2673d57999e1SDave Hansen { 26748a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 26758a5e929dSAl Viro flag--; 2676d57999e1SDave Hansen return flag; 2677d57999e1SDave Hansen } 2678d57999e1SDave Hansen 2679d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2680d18e9008SMiklos Szeredi { 2681d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2682d18e9008SMiklos Szeredi if (error) 2683d18e9008SMiklos Szeredi return error; 2684d18e9008SMiklos Szeredi 2685d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2686d18e9008SMiklos Szeredi if (error) 2687d18e9008SMiklos Szeredi return error; 2688d18e9008SMiklos Szeredi 2689d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2690d18e9008SMiklos Szeredi } 2691d18e9008SMiklos Szeredi 26921acf0af9SDavid Howells /* 26931acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 26941acf0af9SDavid Howells * dentry. 26951acf0af9SDavid Howells * 26961acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 26971acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 26981acf0af9SDavid Howells * 26991acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 27001acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 27011acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 27021acf0af9SDavid Howells * 27031acf0af9SDavid Howells * Returns an error code otherwise. 27041acf0af9SDavid Howells */ 27052675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 270630d90494SAl Viro struct path *path, struct file *file, 2707015c3bbcSMiklos Szeredi const struct open_flags *op, 270864894cf8SAl Viro bool got_write, bool need_lookup, 270947237687SAl Viro int *opened) 2710d18e9008SMiklos Szeredi { 2711d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2712d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2713d18e9008SMiklos Szeredi umode_t mode; 2714d18e9008SMiklos Szeredi int error; 2715d18e9008SMiklos Szeredi int acc_mode; 2716d18e9008SMiklos Szeredi int create_error = 0; 2717d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2718116cc022SMiklos Szeredi bool excl; 2719d18e9008SMiklos Szeredi 2720d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2721d18e9008SMiklos Szeredi 2722d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2723d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 27242675a4ebSAl Viro error = -ENOENT; 2725d18e9008SMiklos Szeredi goto out; 2726d18e9008SMiklos Szeredi } 2727d18e9008SMiklos Szeredi 272862b259d8SMiklos Szeredi mode = op->mode; 2729d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2730d18e9008SMiklos Szeredi mode &= ~current_umask(); 2731d18e9008SMiklos Szeredi 2732116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2733116cc022SMiklos Szeredi if (excl) 2734d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2735d18e9008SMiklos Szeredi 2736d18e9008SMiklos Szeredi /* 2737d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2738d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2739d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2740d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2741d18e9008SMiklos Szeredi * 2742d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2743d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2744d18e9008SMiklos Szeredi */ 274564894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 274664894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 274764894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2748d18e9008SMiklos Szeredi /* 2749d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2750d18e9008SMiklos Szeredi * back to lookup + open 2751d18e9008SMiklos Szeredi */ 2752d18e9008SMiklos Szeredi goto no_open; 2753d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2754d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 275564894cf8SAl Viro create_error = -EROFS; 2756d18e9008SMiklos Szeredi goto no_open; 2757d18e9008SMiklos Szeredi } else { 2758d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 275964894cf8SAl Viro create_error = -EROFS; 2760d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2761d18e9008SMiklos Szeredi } 2762d18e9008SMiklos Szeredi } 2763d18e9008SMiklos Szeredi 2764d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 276538227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2766d18e9008SMiklos Szeredi if (error) { 2767d18e9008SMiklos Szeredi create_error = error; 2768d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2769d18e9008SMiklos Szeredi goto no_open; 2770d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2771d18e9008SMiklos Szeredi } 2772d18e9008SMiklos Szeredi } 2773d18e9008SMiklos Szeredi 2774d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2775d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2776d18e9008SMiklos Szeredi 277730d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 277830d90494SAl Viro file->f_path.mnt = nd->path.mnt; 277930d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 278047237687SAl Viro opened); 2781d9585277SAl Viro if (error < 0) { 2782d9585277SAl Viro if (create_error && error == -ENOENT) 2783d9585277SAl Viro error = create_error; 2784d18e9008SMiklos Szeredi goto out; 2785d18e9008SMiklos Szeredi } 2786d18e9008SMiklos Szeredi 2787d9585277SAl Viro if (error) { /* returned 1, that is */ 278830d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 27892675a4ebSAl Viro error = -EIO; 2790d18e9008SMiklos Szeredi goto out; 2791d18e9008SMiklos Szeredi } 279230d90494SAl Viro if (file->f_path.dentry) { 2793d18e9008SMiklos Szeredi dput(dentry); 279430d90494SAl Viro dentry = file->f_path.dentry; 2795d18e9008SMiklos Szeredi } 279603da633aSAl Viro if (*opened & FILE_CREATED) 279703da633aSAl Viro fsnotify_create(dir, dentry); 279803da633aSAl Viro if (!dentry->d_inode) { 279903da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 280003da633aSAl Viro if (create_error) { 280162b2ce96SSage Weil error = create_error; 280262b2ce96SSage Weil goto out; 280362b2ce96SSage Weil } 280403da633aSAl Viro } else { 280503da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 280603da633aSAl Viro error = -EEXIST; 280703da633aSAl Viro goto out; 280803da633aSAl Viro } 280903da633aSAl Viro } 2810d18e9008SMiklos Szeredi goto looked_up; 2811d18e9008SMiklos Szeredi } 2812d18e9008SMiklos Szeredi 2813d18e9008SMiklos Szeredi /* 2814d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2815d18e9008SMiklos Szeredi * here. 2816d18e9008SMiklos Szeredi */ 281703da633aSAl Viro acc_mode = op->acc_mode; 281803da633aSAl Viro if (*opened & FILE_CREATED) { 281903da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 282003da633aSAl Viro fsnotify_create(dir, dentry); 282103da633aSAl Viro acc_mode = MAY_OPEN; 282203da633aSAl Viro } 28232675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 28242675a4ebSAl Viro if (error) 28252675a4ebSAl Viro fput(file); 2826d18e9008SMiklos Szeredi 2827d18e9008SMiklos Szeredi out: 2828d18e9008SMiklos Szeredi dput(dentry); 28292675a4ebSAl Viro return error; 2830d18e9008SMiklos Szeredi 2831d18e9008SMiklos Szeredi no_open: 2832d18e9008SMiklos Szeredi if (need_lookup) { 283372bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2834d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 28352675a4ebSAl Viro return PTR_ERR(dentry); 2836d18e9008SMiklos Szeredi 2837d18e9008SMiklos Szeredi if (create_error) { 2838d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2839d18e9008SMiklos Szeredi 28402675a4ebSAl Viro error = create_error; 2841d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2842d18e9008SMiklos Szeredi if (!dentry->d_inode) 2843d18e9008SMiklos Szeredi goto out; 2844d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2845d18e9008SMiklos Szeredi goto out; 2846d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2847e36cb0b8SDavid Howells d_is_reg(dentry)) { 2848d18e9008SMiklos Szeredi goto out; 2849d18e9008SMiklos Szeredi } 2850d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2851d18e9008SMiklos Szeredi } 2852d18e9008SMiklos Szeredi } 2853d18e9008SMiklos Szeredi looked_up: 2854d18e9008SMiklos Szeredi path->dentry = dentry; 2855d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 28562675a4ebSAl Viro return 1; 2857d18e9008SMiklos Szeredi } 2858d18e9008SMiklos Szeredi 285931e6b01fSNick Piggin /* 28601acf0af9SDavid Howells * Look up and maybe create and open the last component. 2861d58ffd35SMiklos Szeredi * 2862d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2863d58ffd35SMiklos Szeredi * 28641acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 28651acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 28661acf0af9SDavid Howells * 28671acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 28681acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 28691acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 28701acf0af9SDavid Howells * specified then a negative dentry may be returned. 28711acf0af9SDavid Howells * 28721acf0af9SDavid Howells * An error code is returned otherwise. 28731acf0af9SDavid Howells * 28741acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 28751acf0af9SDavid Howells * cleared otherwise prior to returning. 2876d58ffd35SMiklos Szeredi */ 28772675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 287830d90494SAl Viro struct file *file, 2879d58ffd35SMiklos Szeredi const struct open_flags *op, 288064894cf8SAl Viro bool got_write, int *opened) 2881d58ffd35SMiklos Szeredi { 2882d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 288354ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2884d58ffd35SMiklos Szeredi struct dentry *dentry; 2885d58ffd35SMiklos Szeredi int error; 288654ef4872SMiklos Szeredi bool need_lookup; 2887d58ffd35SMiklos Szeredi 288847237687SAl Viro *opened &= ~FILE_CREATED; 2889201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2890d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 28912675a4ebSAl Viro return PTR_ERR(dentry); 2892d58ffd35SMiklos Szeredi 2893d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2894d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2895d18e9008SMiklos Szeredi goto out_no_open; 2896d18e9008SMiklos Szeredi 2897d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 289864894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 289947237687SAl Viro need_lookup, opened); 2900d18e9008SMiklos Szeredi } 2901d18e9008SMiklos Szeredi 290254ef4872SMiklos Szeredi if (need_lookup) { 290354ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 290454ef4872SMiklos Szeredi 290572bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 290654ef4872SMiklos Szeredi if (IS_ERR(dentry)) 29072675a4ebSAl Viro return PTR_ERR(dentry); 290854ef4872SMiklos Szeredi } 290954ef4872SMiklos Szeredi 2910d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2911d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2912d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2913d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2914d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2915d58ffd35SMiklos Szeredi /* 2916d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2917d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2918d58ffd35SMiklos Szeredi * the time when the file is created and when 2919d58ffd35SMiklos Szeredi * a permanent write count is taken through 2920015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 2921d58ffd35SMiklos Szeredi */ 292264894cf8SAl Viro if (!got_write) { 292364894cf8SAl Viro error = -EROFS; 2924d58ffd35SMiklos Szeredi goto out_dput; 292564894cf8SAl Viro } 292647237687SAl Viro *opened |= FILE_CREATED; 2927d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2928d58ffd35SMiklos Szeredi if (error) 2929d58ffd35SMiklos Szeredi goto out_dput; 2930312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 2931312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 2932d58ffd35SMiklos Szeredi if (error) 2933d58ffd35SMiklos Szeredi goto out_dput; 2934d58ffd35SMiklos Szeredi } 2935d18e9008SMiklos Szeredi out_no_open: 2936d58ffd35SMiklos Szeredi path->dentry = dentry; 2937d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 29382675a4ebSAl Viro return 1; 2939d58ffd35SMiklos Szeredi 2940d58ffd35SMiklos Szeredi out_dput: 2941d58ffd35SMiklos Szeredi dput(dentry); 29422675a4ebSAl Viro return error; 2943d58ffd35SMiklos Szeredi } 2944d58ffd35SMiklos Szeredi 2945d58ffd35SMiklos Szeredi /* 2946fe2d35ffSAl Viro * Handle the last step of open() 294731e6b01fSNick Piggin */ 2948896475d5SAl Viro static int do_last(struct nameidata *nd, 294930d90494SAl Viro struct file *file, const struct open_flags *op, 2950669abf4eSJeff Layton int *opened, struct filename *name) 2951fb1cc555SAl Viro { 2952a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2953ca344a89SAl Viro int open_flag = op->open_flag; 295477d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 295564894cf8SAl Viro bool got_write = false; 2956bcda7652SAl Viro int acc_mode = op->acc_mode; 2957a1eb3315SMiklos Szeredi struct inode *inode; 295816b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 2959896475d5SAl Viro struct path path; 296016b1c1cdSMiklos Szeredi bool retried = false; 296116c2cd71SAl Viro int error; 2962fb1cc555SAl Viro 2963c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2964c3e380b0SAl Viro nd->flags |= op->intent; 2965c3e380b0SAl Viro 2966bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 2967fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 296870291aecSAl Viro if (unlikely(error)) { 296970291aecSAl Viro terminate_walk(nd); 29702675a4ebSAl Viro return error; 297170291aecSAl Viro } 2972e83db167SMiklos Szeredi goto finish_open; 29731f36f774SAl Viro } 2974a2c36b45SAl Viro 2975ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2976fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2977fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2978fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2979896475d5SAl Viro error = lookup_fast(nd, &path, &inode); 298071574865SMiklos Szeredi if (likely(!error)) 298171574865SMiklos Szeredi goto finish_lookup; 298271574865SMiklos Szeredi 2983ce57dfc1SAl Viro if (error < 0) 29842675a4ebSAl Viro goto out; 2985a1eb3315SMiklos Szeredi 298637d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 2987b6183df7SMiklos Szeredi } else { 2988fe2d35ffSAl Viro /* create side of things */ 2989a3fbbde7SAl Viro /* 2990b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 2991b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 2992b6183df7SMiklos Szeredi * about to look up 2993a3fbbde7SAl Viro */ 29949f1fafeeSAl Viro error = complete_walk(nd); 2995e8bb73dfSAl Viro if (error) 29962675a4ebSAl Viro return error; 2997fe2d35ffSAl Viro 299833e2208aSJeff Layton audit_inode(name, dir, LOOKUP_PARENT); 299916c2cd71SAl Viro error = -EISDIR; 30001f36f774SAl Viro /* trailing slashes? */ 300131e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 30022675a4ebSAl Viro goto out; 3003b6183df7SMiklos Szeredi } 30041f36f774SAl Viro 300516b1c1cdSMiklos Szeredi retry_lookup: 300664894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 300764894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 300864894cf8SAl Viro if (!error) 300964894cf8SAl Viro got_write = true; 301064894cf8SAl Viro /* 301164894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 301264894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 301364894cf8SAl Viro * dropping this one anyway. 301464894cf8SAl Viro */ 301564894cf8SAl Viro } 3016a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 3017896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 3018fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 3019fb1cc555SAl Viro 30202675a4ebSAl Viro if (error <= 0) { 30212675a4ebSAl Viro if (error) 3022d58ffd35SMiklos Szeredi goto out; 30236c0d46c4SAl Viro 302447237687SAl Viro if ((*opened & FILE_CREATED) || 3025496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 302677d660a8SMiklos Szeredi will_truncate = false; 3027d18e9008SMiklos Szeredi 3028adb5c247SJeff Layton audit_inode(name, file->f_path.dentry, 0); 3029d18e9008SMiklos Szeredi goto opened; 3030d18e9008SMiklos Szeredi } 3031d18e9008SMiklos Szeredi 303247237687SAl Viro if (*opened & FILE_CREATED) { 30339b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3034ca344a89SAl Viro open_flag &= ~O_TRUNC; 303577d660a8SMiklos Szeredi will_truncate = false; 3036bcda7652SAl Viro acc_mode = MAY_OPEN; 3037896475d5SAl Viro path_to_nameidata(&path, nd); 3038e83db167SMiklos Szeredi goto finish_open_created; 3039fb1cc555SAl Viro } 3040fb1cc555SAl Viro 3041fb1cc555SAl Viro /* 30423134f37eSJeff Layton * create/update audit record if it already exists. 3043fb1cc555SAl Viro */ 3044896475d5SAl Viro if (d_is_positive(path.dentry)) 3045896475d5SAl Viro audit_inode(name, path.dentry, 0); 3046fb1cc555SAl Viro 3047d18e9008SMiklos Szeredi /* 3048d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3049d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3050d18e9008SMiklos Szeredi * necessary...) 3051d18e9008SMiklos Szeredi */ 305264894cf8SAl Viro if (got_write) { 3053d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 305464894cf8SAl Viro got_write = false; 3055d18e9008SMiklos Szeredi } 3056d18e9008SMiklos Szeredi 3057fb1cc555SAl Viro error = -EEXIST; 3058f8310c59SAl Viro if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) 3059fb1cc555SAl Viro goto exit_dput; 3060fb1cc555SAl Viro 3061756daf26SNeilBrown error = follow_managed(&path, nd); 30629875cf80SDavid Howells if (error < 0) 30638402752eSAl Viro goto out; 3064a3fbbde7SAl Viro 3065decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 3066896475d5SAl Viro inode = path.dentry->d_inode; 3067fb1cc555SAl Viro error = -ENOENT; 3068896475d5SAl Viro if (d_is_negative(path.dentry)) { 3069896475d5SAl Viro path_to_nameidata(&path, nd); 30702675a4ebSAl Viro goto out; 307154c33e7fSMiklos Szeredi } 3072766c4cbfSAl Viro finish_lookup: 3073191d7f73SAl Viro if (nd->depth) 3074191d7f73SAl Viro put_link(nd); 3075d63ff28fSAl Viro error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW); 3076d63ff28fSAl Viro if (unlikely(error)) { 3077d63ff28fSAl Viro if (error < 0) 3078d63ff28fSAl Viro goto out; 3079d63ff28fSAl Viro return error; 3080d45ea867SMiklos Szeredi } 3081fb1cc555SAl Viro 3082896475d5SAl Viro if (unlikely(d_is_symlink(path.dentry)) && !(open_flag & O_PATH)) { 3083896475d5SAl Viro path_to_nameidata(&path, nd); 3084a5cfe2d5SAl Viro error = -ELOOP; 3085a5cfe2d5SAl Viro goto out; 3086a5cfe2d5SAl Viro } 3087a5cfe2d5SAl Viro 3088896475d5SAl Viro if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { 3089896475d5SAl Viro path_to_nameidata(&path, nd); 309016b1c1cdSMiklos Szeredi } else { 309116b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 3092896475d5SAl Viro save_parent.mnt = mntget(path.mnt); 3093896475d5SAl Viro nd->path.dentry = path.dentry; 309416b1c1cdSMiklos Szeredi 309516b1c1cdSMiklos Szeredi } 3096decf3400SMiklos Szeredi nd->inode = inode; 3097a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3098bc77daa7SAl Viro finish_open: 3099a3fbbde7SAl Viro error = complete_walk(nd); 310016b1c1cdSMiklos Szeredi if (error) { 310116b1c1cdSMiklos Szeredi path_put(&save_parent); 31022675a4ebSAl Viro return error; 310316b1c1cdSMiklos Szeredi } 3104bc77daa7SAl Viro audit_inode(name, nd->path.dentry, 0); 3105fb1cc555SAl Viro error = -EISDIR; 310644b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 31072675a4ebSAl Viro goto out; 3108af2f5542SMiklos Szeredi error = -ENOTDIR; 310944b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 31102675a4ebSAl Viro goto out; 31114bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 311277d660a8SMiklos Szeredi will_truncate = false; 31136c0d46c4SAl Viro 31140f9d1a10SAl Viro if (will_truncate) { 31150f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 31160f9d1a10SAl Viro if (error) 31172675a4ebSAl Viro goto out; 311864894cf8SAl Viro got_write = true; 31190f9d1a10SAl Viro } 3120e83db167SMiklos Szeredi finish_open_created: 3121bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3122ca344a89SAl Viro if (error) 31232675a4ebSAl Viro goto out; 31244aa7c634SMiklos Szeredi 31254aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 31264aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 31274aa7c634SMiklos Szeredi if (!error) { 31284aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 31294aa7c634SMiklos Szeredi } else { 313030d90494SAl Viro if (error == -EOPENSTALE) 3131f60dc3dbSMiklos Szeredi goto stale_open; 3132015c3bbcSMiklos Szeredi goto out; 3133f60dc3dbSMiklos Szeredi } 3134a8277b9bSMiklos Szeredi opened: 31352675a4ebSAl Viro error = open_check_o_direct(file); 3136015c3bbcSMiklos Szeredi if (error) 3137015c3bbcSMiklos Szeredi goto exit_fput; 31383034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3139aa4caadbSMiklos Szeredi if (error) 3140aa4caadbSMiklos Szeredi goto exit_fput; 3141aa4caadbSMiklos Szeredi 31420f9d1a10SAl Viro if (will_truncate) { 31432675a4ebSAl Viro error = handle_truncate(file); 3144aa4caadbSMiklos Szeredi if (error) 3145aa4caadbSMiklos Szeredi goto exit_fput; 31460f9d1a10SAl Viro } 3147ca344a89SAl Viro out: 314864894cf8SAl Viro if (got_write) 31490f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 315016b1c1cdSMiklos Szeredi path_put(&save_parent); 3151e276ae67SMiklos Szeredi terminate_walk(nd); 31522675a4ebSAl Viro return error; 3153fb1cc555SAl Viro 3154fb1cc555SAl Viro exit_dput: 3155896475d5SAl Viro path_put_conditional(&path, nd); 3156ca344a89SAl Viro goto out; 3157015c3bbcSMiklos Szeredi exit_fput: 31582675a4ebSAl Viro fput(file); 31592675a4ebSAl Viro goto out; 3160015c3bbcSMiklos Szeredi 3161f60dc3dbSMiklos Szeredi stale_open: 3162f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3163f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3164f60dc3dbSMiklos Szeredi goto out; 3165f60dc3dbSMiklos Szeredi 3166f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3167f60dc3dbSMiklos Szeredi path_put(&nd->path); 3168f60dc3dbSMiklos Szeredi nd->path = save_parent; 3169f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3170f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3171f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 317264894cf8SAl Viro if (got_write) { 3173f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 317464894cf8SAl Viro got_write = false; 3175f60dc3dbSMiklos Szeredi } 3176f60dc3dbSMiklos Szeredi retried = true; 3177f60dc3dbSMiklos Szeredi goto retry_lookup; 3178fb1cc555SAl Viro } 3179fb1cc555SAl Viro 318060545d0dSAl Viro static int do_tmpfile(int dfd, struct filename *pathname, 318160545d0dSAl Viro struct nameidata *nd, int flags, 318260545d0dSAl Viro const struct open_flags *op, 318360545d0dSAl Viro struct file *file, int *opened) 318460545d0dSAl Viro { 318560545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 318660545d0dSAl Viro struct dentry *dentry, *child; 318760545d0dSAl Viro struct inode *dir; 31885eb6b495SAl Viro int error = path_lookupat(dfd, pathname, 318960545d0dSAl Viro flags | LOOKUP_DIRECTORY, nd); 319060545d0dSAl Viro if (unlikely(error)) 319160545d0dSAl Viro return error; 319260545d0dSAl Viro error = mnt_want_write(nd->path.mnt); 319360545d0dSAl Viro if (unlikely(error)) 319460545d0dSAl Viro goto out; 319560545d0dSAl Viro /* we want directory to be writable */ 319660545d0dSAl Viro error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); 319760545d0dSAl Viro if (error) 319860545d0dSAl Viro goto out2; 319960545d0dSAl Viro dentry = nd->path.dentry; 320060545d0dSAl Viro dir = dentry->d_inode; 320160545d0dSAl Viro if (!dir->i_op->tmpfile) { 320260545d0dSAl Viro error = -EOPNOTSUPP; 320360545d0dSAl Viro goto out2; 320460545d0dSAl Viro } 320560545d0dSAl Viro child = d_alloc(dentry, &name); 320660545d0dSAl Viro if (unlikely(!child)) { 320760545d0dSAl Viro error = -ENOMEM; 320860545d0dSAl Viro goto out2; 320960545d0dSAl Viro } 321060545d0dSAl Viro nd->flags &= ~LOOKUP_DIRECTORY; 321160545d0dSAl Viro nd->flags |= op->intent; 321260545d0dSAl Viro dput(nd->path.dentry); 321360545d0dSAl Viro nd->path.dentry = child; 321460545d0dSAl Viro error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); 321560545d0dSAl Viro if (error) 321660545d0dSAl Viro goto out2; 321760545d0dSAl Viro audit_inode(pathname, nd->path.dentry, 0); 321869a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 321969a91c23SEric Rannaud error = may_open(&nd->path, MAY_OPEN, op->open_flag); 322060545d0dSAl Viro if (error) 322160545d0dSAl Viro goto out2; 322260545d0dSAl Viro file->f_path.mnt = nd->path.mnt; 322360545d0dSAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 322460545d0dSAl Viro if (error) 322560545d0dSAl Viro goto out2; 322660545d0dSAl Viro error = open_check_o_direct(file); 3227f4e0c30cSAl Viro if (error) { 322860545d0dSAl Viro fput(file); 3229f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3230f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3231f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3232f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3233f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3234f4e0c30cSAl Viro } 323560545d0dSAl Viro out2: 323660545d0dSAl Viro mnt_drop_write(nd->path.mnt); 323760545d0dSAl Viro out: 323860545d0dSAl Viro path_put(&nd->path); 323960545d0dSAl Viro return error; 324060545d0dSAl Viro } 324160545d0dSAl Viro 3242669abf4eSJeff Layton static struct file *path_openat(int dfd, struct filename *pathname, 324373d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 32441da177e4SLinus Torvalds { 324530d90494SAl Viro struct file *file; 324647237687SAl Viro int opened = 0; 324713aab428SAl Viro int error; 324831e6b01fSNick Piggin 324930d90494SAl Viro file = get_empty_filp(); 32501afc99beSAl Viro if (IS_ERR(file)) 32511afc99beSAl Viro return file; 325231e6b01fSNick Piggin 325330d90494SAl Viro file->f_flags = op->open_flag; 325431e6b01fSNick Piggin 3255bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 325660545d0dSAl Viro error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); 3257f15133dfSAl Viro goto out2; 325860545d0dSAl Viro } 325960545d0dSAl Viro 32606e8a1f87SAl Viro error = path_init(dfd, pathname, flags, nd); 326131e6b01fSNick Piggin if (unlikely(error)) 32622675a4ebSAl Viro goto out; 32631da177e4SLinus Torvalds 3264191d7f73SAl Viro while ((error = do_last(nd, file, op, &opened, pathname)) > 0) { 326573d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 32661d8e03d3SAl Viro error = trailing_symlink(nd); 3267c3e380b0SAl Viro if (unlikely(error)) 32682675a4ebSAl Viro break; 3269806b681cSAl Viro } 327010fa8e62SAl Viro out: 3271893b7775SAl Viro path_cleanup(nd); 3272f15133dfSAl Viro out2: 32732675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 32742675a4ebSAl Viro BUG_ON(!error); 327530d90494SAl Viro put_filp(file); 3276015c3bbcSMiklos Szeredi } 32772675a4ebSAl Viro if (unlikely(error)) { 32782675a4ebSAl Viro if (error == -EOPENSTALE) { 32792675a4ebSAl Viro if (flags & LOOKUP_RCU) 32802675a4ebSAl Viro error = -ECHILD; 32812675a4ebSAl Viro else 32822675a4ebSAl Viro error = -ESTALE; 32832675a4ebSAl Viro } 32842675a4ebSAl Viro file = ERR_PTR(error); 32852675a4ebSAl Viro } 32862675a4ebSAl Viro return file; 3287de459215SKirill Korotaev } 32881da177e4SLinus Torvalds 3289669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3290f9652e10SAl Viro const struct open_flags *op) 329113aab428SAl Viro { 3292756daf26SNeilBrown struct nameidata nd, *saved_nd = set_nameidata(&nd); 3293f9652e10SAl Viro int flags = op->lookup_flags; 329413aab428SAl Viro struct file *filp; 329513aab428SAl Viro 329673d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 329713aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 329873d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 329913aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 330073d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 3301756daf26SNeilBrown restore_nameidata(saved_nd); 330213aab428SAl Viro return filp; 330313aab428SAl Viro } 330413aab428SAl Viro 330573d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3306f9652e10SAl Viro const char *name, const struct open_flags *op) 330773d049a4SAl Viro { 3308756daf26SNeilBrown struct nameidata nd, *saved_nd; 330973d049a4SAl Viro struct file *file; 331051689104SPaul Moore struct filename *filename; 3311f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 331273d049a4SAl Viro 331373d049a4SAl Viro nd.root.mnt = mnt; 331473d049a4SAl Viro nd.root.dentry = dentry; 331573d049a4SAl Viro 3316b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 331773d049a4SAl Viro return ERR_PTR(-ELOOP); 331873d049a4SAl Viro 331951689104SPaul Moore filename = getname_kernel(name); 332051689104SPaul Moore if (unlikely(IS_ERR(filename))) 332151689104SPaul Moore return ERR_CAST(filename); 332251689104SPaul Moore 3323756daf26SNeilBrown saved_nd = set_nameidata(&nd); 332451689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_RCU); 332573d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 332651689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags); 332773d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 332851689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_REVAL); 3329756daf26SNeilBrown restore_nameidata(saved_nd); 333051689104SPaul Moore putname(filename); 333173d049a4SAl Viro return file; 333273d049a4SAl Viro } 333373d049a4SAl Viro 3334fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 33351ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 33361da177e4SLinus Torvalds { 3337c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3338ed75e95dSAl Viro struct nameidata nd; 3339c30dabfeSJan Kara int err2; 33401ac12b4bSJeff Layton int error; 33411ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 33421ac12b4bSJeff Layton 33431ac12b4bSJeff Layton /* 33441ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 33451ac12b4bSJeff Layton * other flags passed in are ignored! 33461ac12b4bSJeff Layton */ 33471ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 33481ac12b4bSJeff Layton 3349fa14a0b8SAl Viro error = filename_lookup(dfd, name, LOOKUP_PARENT|lookup_flags, &nd); 3350ed75e95dSAl Viro if (error) 3351ed75e95dSAl Viro return ERR_PTR(error); 33521da177e4SLinus Torvalds 3353c663e5d8SChristoph Hellwig /* 3354c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3355c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3356c663e5d8SChristoph Hellwig */ 3357ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 3358ed75e95dSAl Viro goto out; 3359ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 3360ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 3361c663e5d8SChristoph Hellwig 3362c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3363c30dabfeSJan Kara err2 = mnt_want_write(nd.path.mnt); 3364c663e5d8SChristoph Hellwig /* 3365c663e5d8SChristoph Hellwig * Do the final lookup. 3366c663e5d8SChristoph Hellwig */ 3367ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 33686a9f40d6SAl Viro dentry = __lookup_hash(&nd.last, nd.path.dentry, nd.flags); 33691da177e4SLinus Torvalds if (IS_ERR(dentry)) 3370a8104a9fSAl Viro goto unlock; 3371c663e5d8SChristoph Hellwig 3372a8104a9fSAl Viro error = -EEXIST; 3373b18825a7SDavid Howells if (d_is_positive(dentry)) 3374a8104a9fSAl Viro goto fail; 3375b18825a7SDavid Howells 3376c663e5d8SChristoph Hellwig /* 3377c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3378c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3379c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3380c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3381c663e5d8SChristoph Hellwig */ 3382ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 3383a8104a9fSAl Viro error = -ENOENT; 3384ed75e95dSAl Viro goto fail; 3385e9baf6e5SAl Viro } 3386c30dabfeSJan Kara if (unlikely(err2)) { 3387c30dabfeSJan Kara error = err2; 3388a8104a9fSAl Viro goto fail; 3389c30dabfeSJan Kara } 3390ed75e95dSAl Viro *path = nd.path; 3391e9baf6e5SAl Viro return dentry; 33921da177e4SLinus Torvalds fail: 3393a8104a9fSAl Viro dput(dentry); 3394a8104a9fSAl Viro dentry = ERR_PTR(error); 3395a8104a9fSAl Viro unlock: 3396dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3397c30dabfeSJan Kara if (!err2) 3398c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 3399ed75e95dSAl Viro out: 3400dae6ad8fSAl Viro path_put(&nd.path); 3401ed75e95dSAl Viro return dentry; 3402dae6ad8fSAl Viro } 3403fa14a0b8SAl Viro 3404fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3405fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3406fa14a0b8SAl Viro { 340751689104SPaul Moore struct filename *filename = getname_kernel(pathname); 340851689104SPaul Moore struct dentry *res; 340951689104SPaul Moore 341051689104SPaul Moore if (IS_ERR(filename)) 341151689104SPaul Moore return ERR_CAST(filename); 341251689104SPaul Moore res = filename_create(dfd, filename, path, lookup_flags); 341351689104SPaul Moore putname(filename); 341451689104SPaul Moore return res; 3415fa14a0b8SAl Viro } 3416dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3417dae6ad8fSAl Viro 3418921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3419921a1650SAl Viro { 3420921a1650SAl Viro dput(dentry); 3421921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3422a8104a9fSAl Viro mnt_drop_write(path->mnt); 3423921a1650SAl Viro path_put(path); 3424921a1650SAl Viro } 3425921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3426921a1650SAl Viro 34271ac12b4bSJeff Layton struct dentry *user_path_create(int dfd, const char __user *pathname, 34281ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3429dae6ad8fSAl Viro { 343091a27b2aSJeff Layton struct filename *tmp = getname(pathname); 3431dae6ad8fSAl Viro struct dentry *res; 3432dae6ad8fSAl Viro if (IS_ERR(tmp)) 3433dae6ad8fSAl Viro return ERR_CAST(tmp); 3434fa14a0b8SAl Viro res = filename_create(dfd, tmp, path, lookup_flags); 3435dae6ad8fSAl Viro putname(tmp); 3436dae6ad8fSAl Viro return res; 3437dae6ad8fSAl Viro } 3438dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3439dae6ad8fSAl Viro 34401a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 34411da177e4SLinus Torvalds { 3442a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 34431da177e4SLinus Torvalds 34441da177e4SLinus Torvalds if (error) 34451da177e4SLinus Torvalds return error; 34461da177e4SLinus Torvalds 3447975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 34481da177e4SLinus Torvalds return -EPERM; 34491da177e4SLinus Torvalds 3450acfa4380SAl Viro if (!dir->i_op->mknod) 34511da177e4SLinus Torvalds return -EPERM; 34521da177e4SLinus Torvalds 345308ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 345408ce5f16SSerge E. Hallyn if (error) 345508ce5f16SSerge E. Hallyn return error; 345608ce5f16SSerge E. Hallyn 34571da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 34581da177e4SLinus Torvalds if (error) 34591da177e4SLinus Torvalds return error; 34601da177e4SLinus Torvalds 34611da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3462a74574aaSStephen Smalley if (!error) 3463f38aa942SAmy Griffis fsnotify_create(dir, dentry); 34641da177e4SLinus Torvalds return error; 34651da177e4SLinus Torvalds } 34664d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 34671da177e4SLinus Torvalds 3468f69aac00SAl Viro static int may_mknod(umode_t mode) 3469463c3197SDave Hansen { 3470463c3197SDave Hansen switch (mode & S_IFMT) { 3471463c3197SDave Hansen case S_IFREG: 3472463c3197SDave Hansen case S_IFCHR: 3473463c3197SDave Hansen case S_IFBLK: 3474463c3197SDave Hansen case S_IFIFO: 3475463c3197SDave Hansen case S_IFSOCK: 3476463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3477463c3197SDave Hansen return 0; 3478463c3197SDave Hansen case S_IFDIR: 3479463c3197SDave Hansen return -EPERM; 3480463c3197SDave Hansen default: 3481463c3197SDave Hansen return -EINVAL; 3482463c3197SDave Hansen } 3483463c3197SDave Hansen } 3484463c3197SDave Hansen 34858208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 34862e4d0924SHeiko Carstens unsigned, dev) 34871da177e4SLinus Torvalds { 34881da177e4SLinus Torvalds struct dentry *dentry; 3489dae6ad8fSAl Viro struct path path; 3490dae6ad8fSAl Viro int error; 3491972567f1SJeff Layton unsigned int lookup_flags = 0; 34921da177e4SLinus Torvalds 34938e4bfca1SAl Viro error = may_mknod(mode); 34948e4bfca1SAl Viro if (error) 34958e4bfca1SAl Viro return error; 3496972567f1SJeff Layton retry: 3497972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3498dae6ad8fSAl Viro if (IS_ERR(dentry)) 3499dae6ad8fSAl Viro return PTR_ERR(dentry); 35002ad94ae6SAl Viro 3501dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3502ce3b0f8dSAl Viro mode &= ~current_umask(); 3503dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3504be6d3e56SKentaro Takeda if (error) 3505a8104a9fSAl Viro goto out; 35061da177e4SLinus Torvalds switch (mode & S_IFMT) { 35071da177e4SLinus Torvalds case 0: case S_IFREG: 3508312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 35091da177e4SLinus Torvalds break; 35101da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3511dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 35121da177e4SLinus Torvalds new_decode_dev(dev)); 35131da177e4SLinus Torvalds break; 35141da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3515dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 35161da177e4SLinus Torvalds break; 35171da177e4SLinus Torvalds } 3518a8104a9fSAl Viro out: 3519921a1650SAl Viro done_path_create(&path, dentry); 3520972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3521972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3522972567f1SJeff Layton goto retry; 3523972567f1SJeff Layton } 35241da177e4SLinus Torvalds return error; 35251da177e4SLinus Torvalds } 35261da177e4SLinus Torvalds 35278208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 35285590ff0dSUlrich Drepper { 35295590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 35305590ff0dSUlrich Drepper } 35315590ff0dSUlrich Drepper 353218bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 35331da177e4SLinus Torvalds { 3534a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35358de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 35361da177e4SLinus Torvalds 35371da177e4SLinus Torvalds if (error) 35381da177e4SLinus Torvalds return error; 35391da177e4SLinus Torvalds 3540acfa4380SAl Viro if (!dir->i_op->mkdir) 35411da177e4SLinus Torvalds return -EPERM; 35421da177e4SLinus Torvalds 35431da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 35441da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 35451da177e4SLinus Torvalds if (error) 35461da177e4SLinus Torvalds return error; 35471da177e4SLinus Torvalds 35488de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 35498de52778SAl Viro return -EMLINK; 35508de52778SAl Viro 35511da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3552a74574aaSStephen Smalley if (!error) 3553f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 35541da177e4SLinus Torvalds return error; 35551da177e4SLinus Torvalds } 35564d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 35571da177e4SLinus Torvalds 3558a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 35591da177e4SLinus Torvalds { 35606902d925SDave Hansen struct dentry *dentry; 3561dae6ad8fSAl Viro struct path path; 3562dae6ad8fSAl Viro int error; 3563b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 35641da177e4SLinus Torvalds 3565b76d8b82SJeff Layton retry: 3566b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 35676902d925SDave Hansen if (IS_ERR(dentry)) 3568dae6ad8fSAl Viro return PTR_ERR(dentry); 35696902d925SDave Hansen 3570dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3571ce3b0f8dSAl Viro mode &= ~current_umask(); 3572dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3573a8104a9fSAl Viro if (!error) 3574dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3575921a1650SAl Viro done_path_create(&path, dentry); 3576b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3577b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3578b76d8b82SJeff Layton goto retry; 3579b76d8b82SJeff Layton } 35801da177e4SLinus Torvalds return error; 35811da177e4SLinus Torvalds } 35821da177e4SLinus Torvalds 3583a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 35845590ff0dSUlrich Drepper { 35855590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 35865590ff0dSUlrich Drepper } 35875590ff0dSUlrich Drepper 35881da177e4SLinus Torvalds /* 3589a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3590c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3591a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3592a71905f0SSage Weil * then we drop the dentry now. 35931da177e4SLinus Torvalds * 35941da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 35951da177e4SLinus Torvalds * do a 35961da177e4SLinus Torvalds * 35971da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 35981da177e4SLinus Torvalds * return -EBUSY; 35991da177e4SLinus Torvalds * 36001da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 36011da177e4SLinus Torvalds * that is still in use by something else.. 36021da177e4SLinus Torvalds */ 36031da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 36041da177e4SLinus Torvalds { 36051da177e4SLinus Torvalds shrink_dcache_parent(dentry); 36061da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 360798474236SWaiman Long if (dentry->d_lockref.count == 1) 36081da177e4SLinus Torvalds __d_drop(dentry); 36091da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 36101da177e4SLinus Torvalds } 36114d359507SAl Viro EXPORT_SYMBOL(dentry_unhash); 36121da177e4SLinus Torvalds 36131da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 36141da177e4SLinus Torvalds { 36151da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 36161da177e4SLinus Torvalds 36171da177e4SLinus Torvalds if (error) 36181da177e4SLinus Torvalds return error; 36191da177e4SLinus Torvalds 3620acfa4380SAl Viro if (!dir->i_op->rmdir) 36211da177e4SLinus Torvalds return -EPERM; 36221da177e4SLinus Torvalds 36231d2ef590SAl Viro dget(dentry); 36241b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3625912dbc15SSage Weil 36261da177e4SLinus Torvalds error = -EBUSY; 36277af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3628912dbc15SSage Weil goto out; 3629912dbc15SSage Weil 36301da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3631912dbc15SSage Weil if (error) 3632912dbc15SSage Weil goto out; 3633912dbc15SSage Weil 36343cebde24SSage Weil shrink_dcache_parent(dentry); 36351da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3636912dbc15SSage Weil if (error) 3637912dbc15SSage Weil goto out; 3638912dbc15SSage Weil 36391da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3640d83c49f3SAl Viro dont_mount(dentry); 36418ed936b5SEric W. Biederman detach_mounts(dentry); 36421da177e4SLinus Torvalds 3643912dbc15SSage Weil out: 3644912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 36451d2ef590SAl Viro dput(dentry); 3646912dbc15SSage Weil if (!error) 3647912dbc15SSage Weil d_delete(dentry); 36481da177e4SLinus Torvalds return error; 36491da177e4SLinus Torvalds } 36504d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 36511da177e4SLinus Torvalds 36525590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 36531da177e4SLinus Torvalds { 36541da177e4SLinus Torvalds int error = 0; 365591a27b2aSJeff Layton struct filename *name; 36561da177e4SLinus Torvalds struct dentry *dentry; 3657f5beed75SAl Viro struct path path; 3658f5beed75SAl Viro struct qstr last; 3659f5beed75SAl Viro int type; 3660c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3661c6ee9206SJeff Layton retry: 3662f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3663f5beed75SAl Viro &path, &last, &type, lookup_flags); 366491a27b2aSJeff Layton if (IS_ERR(name)) 366591a27b2aSJeff Layton return PTR_ERR(name); 36661da177e4SLinus Torvalds 3667f5beed75SAl Viro switch (type) { 36681da177e4SLinus Torvalds case LAST_DOTDOT: 36691da177e4SLinus Torvalds error = -ENOTEMPTY; 36701da177e4SLinus Torvalds goto exit1; 36711da177e4SLinus Torvalds case LAST_DOT: 36721da177e4SLinus Torvalds error = -EINVAL; 36731da177e4SLinus Torvalds goto exit1; 36741da177e4SLinus Torvalds case LAST_ROOT: 36751da177e4SLinus Torvalds error = -EBUSY; 36761da177e4SLinus Torvalds goto exit1; 36771da177e4SLinus Torvalds } 36780612d9fbSOGAWA Hirofumi 3679f5beed75SAl Viro error = mnt_want_write(path.mnt); 3680c30dabfeSJan Kara if (error) 3681c30dabfeSJan Kara goto exit1; 36820612d9fbSOGAWA Hirofumi 3683f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3684f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 36851da177e4SLinus Torvalds error = PTR_ERR(dentry); 36866902d925SDave Hansen if (IS_ERR(dentry)) 36876902d925SDave Hansen goto exit2; 3688e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3689e6bc45d6STheodore Ts'o error = -ENOENT; 3690e6bc45d6STheodore Ts'o goto exit3; 3691e6bc45d6STheodore Ts'o } 3692f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3693be6d3e56SKentaro Takeda if (error) 3694c30dabfeSJan Kara goto exit3; 3695f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 36960622753bSDave Hansen exit3: 36971da177e4SLinus Torvalds dput(dentry); 36986902d925SDave Hansen exit2: 3699f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 3700f5beed75SAl Viro mnt_drop_write(path.mnt); 37011da177e4SLinus Torvalds exit1: 3702f5beed75SAl Viro path_put(&path); 37031da177e4SLinus Torvalds putname(name); 3704c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3705c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3706c6ee9206SJeff Layton goto retry; 3707c6ee9206SJeff Layton } 37081da177e4SLinus Torvalds return error; 37091da177e4SLinus Torvalds } 37101da177e4SLinus Torvalds 37113cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 37125590ff0dSUlrich Drepper { 37135590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 37145590ff0dSUlrich Drepper } 37155590ff0dSUlrich Drepper 3716b21996e3SJ. Bruce Fields /** 3717b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3718b21996e3SJ. Bruce Fields * @dir: parent directory 3719b21996e3SJ. Bruce Fields * @dentry: victim 3720b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3721b21996e3SJ. Bruce Fields * 3722b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3723b21996e3SJ. Bruce Fields * 3724b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3725b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3726b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3727b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3728b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3729b21996e3SJ. Bruce Fields * 3730b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3731b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3732b21996e3SJ. Bruce Fields * to be NFS exported. 3733b21996e3SJ. Bruce Fields */ 3734b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 37351da177e4SLinus Torvalds { 37369accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 37371da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 37381da177e4SLinus Torvalds 37391da177e4SLinus Torvalds if (error) 37401da177e4SLinus Torvalds return error; 37411da177e4SLinus Torvalds 3742acfa4380SAl Viro if (!dir->i_op->unlink) 37431da177e4SLinus Torvalds return -EPERM; 37441da177e4SLinus Torvalds 37459accbb97SJ. Bruce Fields mutex_lock(&target->i_mutex); 37468ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 37471da177e4SLinus Torvalds error = -EBUSY; 37481da177e4SLinus Torvalds else { 37491da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3750bec1052eSAl Viro if (!error) { 37515a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 37525a14696cSJ. Bruce Fields if (error) 3753b21996e3SJ. Bruce Fields goto out; 37541da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 37558ed936b5SEric W. Biederman if (!error) { 3756d83c49f3SAl Viro dont_mount(dentry); 37578ed936b5SEric W. Biederman detach_mounts(dentry); 37588ed936b5SEric W. Biederman } 3759bec1052eSAl Viro } 37601da177e4SLinus Torvalds } 3761b21996e3SJ. Bruce Fields out: 37629accbb97SJ. Bruce Fields mutex_unlock(&target->i_mutex); 37631da177e4SLinus Torvalds 37641da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 37651da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 37669accbb97SJ. Bruce Fields fsnotify_link_count(target); 37671da177e4SLinus Torvalds d_delete(dentry); 37681da177e4SLinus Torvalds } 37690eeca283SRobert Love 37701da177e4SLinus Torvalds return error; 37711da177e4SLinus Torvalds } 37724d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 37731da177e4SLinus Torvalds 37741da177e4SLinus Torvalds /* 37751da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 37761b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 37771da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 37781da177e4SLinus Torvalds * while waiting on the I/O. 37791da177e4SLinus Torvalds */ 37805590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 37811da177e4SLinus Torvalds { 37822ad94ae6SAl Viro int error; 378391a27b2aSJeff Layton struct filename *name; 37841da177e4SLinus Torvalds struct dentry *dentry; 3785f5beed75SAl Viro struct path path; 3786f5beed75SAl Viro struct qstr last; 3787f5beed75SAl Viro int type; 37881da177e4SLinus Torvalds struct inode *inode = NULL; 3789b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 37905d18f813SJeff Layton unsigned int lookup_flags = 0; 37915d18f813SJeff Layton retry: 3792f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3793f5beed75SAl Viro &path, &last, &type, lookup_flags); 379491a27b2aSJeff Layton if (IS_ERR(name)) 379591a27b2aSJeff Layton return PTR_ERR(name); 37962ad94ae6SAl Viro 37971da177e4SLinus Torvalds error = -EISDIR; 3798f5beed75SAl Viro if (type != LAST_NORM) 37991da177e4SLinus Torvalds goto exit1; 38000612d9fbSOGAWA Hirofumi 3801f5beed75SAl Viro error = mnt_want_write(path.mnt); 3802c30dabfeSJan Kara if (error) 3803c30dabfeSJan Kara goto exit1; 3804b21996e3SJ. Bruce Fields retry_deleg: 3805f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3806f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38071da177e4SLinus Torvalds error = PTR_ERR(dentry); 38081da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 38091da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3810f5beed75SAl Viro if (last.name[last.len]) 381150338b88STörök Edwin goto slashes; 38121da177e4SLinus Torvalds inode = dentry->d_inode; 3813b18825a7SDavid Howells if (d_is_negative(dentry)) 3814e6bc45d6STheodore Ts'o goto slashes; 38157de9c6eeSAl Viro ihold(inode); 3816f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3817be6d3e56SKentaro Takeda if (error) 3818c30dabfeSJan Kara goto exit2; 3819f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 38201da177e4SLinus Torvalds exit2: 38211da177e4SLinus Torvalds dput(dentry); 38221da177e4SLinus Torvalds } 3823f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 38241da177e4SLinus Torvalds if (inode) 38251da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3826b21996e3SJ. Bruce Fields inode = NULL; 3827b21996e3SJ. Bruce Fields if (delegated_inode) { 38285a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3829b21996e3SJ. Bruce Fields if (!error) 3830b21996e3SJ. Bruce Fields goto retry_deleg; 3831b21996e3SJ. Bruce Fields } 3832f5beed75SAl Viro mnt_drop_write(path.mnt); 38331da177e4SLinus Torvalds exit1: 3834f5beed75SAl Viro path_put(&path); 38351da177e4SLinus Torvalds putname(name); 38365d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 38375d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 38385d18f813SJeff Layton inode = NULL; 38395d18f813SJeff Layton goto retry; 38405d18f813SJeff Layton } 38411da177e4SLinus Torvalds return error; 38421da177e4SLinus Torvalds 38431da177e4SLinus Torvalds slashes: 3844b18825a7SDavid Howells if (d_is_negative(dentry)) 3845b18825a7SDavid Howells error = -ENOENT; 384644b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3847b18825a7SDavid Howells error = -EISDIR; 3848b18825a7SDavid Howells else 3849b18825a7SDavid Howells error = -ENOTDIR; 38501da177e4SLinus Torvalds goto exit2; 38511da177e4SLinus Torvalds } 38521da177e4SLinus Torvalds 38532e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 38545590ff0dSUlrich Drepper { 38555590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 38565590ff0dSUlrich Drepper return -EINVAL; 38575590ff0dSUlrich Drepper 38585590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 38595590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 38605590ff0dSUlrich Drepper 38615590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 38625590ff0dSUlrich Drepper } 38635590ff0dSUlrich Drepper 38643480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 38655590ff0dSUlrich Drepper { 38665590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 38675590ff0dSUlrich Drepper } 38685590ff0dSUlrich Drepper 3869db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 38701da177e4SLinus Torvalds { 3871a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 38721da177e4SLinus Torvalds 38731da177e4SLinus Torvalds if (error) 38741da177e4SLinus Torvalds return error; 38751da177e4SLinus Torvalds 3876acfa4380SAl Viro if (!dir->i_op->symlink) 38771da177e4SLinus Torvalds return -EPERM; 38781da177e4SLinus Torvalds 38791da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 38801da177e4SLinus Torvalds if (error) 38811da177e4SLinus Torvalds return error; 38821da177e4SLinus Torvalds 38831da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3884a74574aaSStephen Smalley if (!error) 3885f38aa942SAmy Griffis fsnotify_create(dir, dentry); 38861da177e4SLinus Torvalds return error; 38871da177e4SLinus Torvalds } 38884d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 38891da177e4SLinus Torvalds 38902e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 38912e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 38921da177e4SLinus Torvalds { 38932ad94ae6SAl Viro int error; 389491a27b2aSJeff Layton struct filename *from; 38956902d925SDave Hansen struct dentry *dentry; 3896dae6ad8fSAl Viro struct path path; 3897f46d3567SJeff Layton unsigned int lookup_flags = 0; 38981da177e4SLinus Torvalds 38991da177e4SLinus Torvalds from = getname(oldname); 39001da177e4SLinus Torvalds if (IS_ERR(from)) 39011da177e4SLinus Torvalds return PTR_ERR(from); 3902f46d3567SJeff Layton retry: 3903f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 39041da177e4SLinus Torvalds error = PTR_ERR(dentry); 39056902d925SDave Hansen if (IS_ERR(dentry)) 3906dae6ad8fSAl Viro goto out_putname; 39076902d925SDave Hansen 390891a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3909a8104a9fSAl Viro if (!error) 391091a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3911921a1650SAl Viro done_path_create(&path, dentry); 3912f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 3913f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 3914f46d3567SJeff Layton goto retry; 3915f46d3567SJeff Layton } 39166902d925SDave Hansen out_putname: 39171da177e4SLinus Torvalds putname(from); 39181da177e4SLinus Torvalds return error; 39191da177e4SLinus Torvalds } 39201da177e4SLinus Torvalds 39213480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 39225590ff0dSUlrich Drepper { 39235590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 39245590ff0dSUlrich Drepper } 39255590ff0dSUlrich Drepper 3926146a8595SJ. Bruce Fields /** 3927146a8595SJ. Bruce Fields * vfs_link - create a new link 3928146a8595SJ. Bruce Fields * @old_dentry: object to be linked 3929146a8595SJ. Bruce Fields * @dir: new parent 3930146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 3931146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 3932146a8595SJ. Bruce Fields * 3933146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 3934146a8595SJ. Bruce Fields * 3935146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 3936146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 3937146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 3938146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 3939146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 3940146a8595SJ. Bruce Fields * 3941146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3942146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3943146a8595SJ. Bruce Fields * to be NFS exported. 3944146a8595SJ. Bruce Fields */ 3945146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 39461da177e4SLinus Torvalds { 39471da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 39488de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 39491da177e4SLinus Torvalds int error; 39501da177e4SLinus Torvalds 39511da177e4SLinus Torvalds if (!inode) 39521da177e4SLinus Torvalds return -ENOENT; 39531da177e4SLinus Torvalds 3954a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 39551da177e4SLinus Torvalds if (error) 39561da177e4SLinus Torvalds return error; 39571da177e4SLinus Torvalds 39581da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 39591da177e4SLinus Torvalds return -EXDEV; 39601da177e4SLinus Torvalds 39611da177e4SLinus Torvalds /* 39621da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 39631da177e4SLinus Torvalds */ 39641da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 39651da177e4SLinus Torvalds return -EPERM; 3966acfa4380SAl Viro if (!dir->i_op->link) 39671da177e4SLinus Torvalds return -EPERM; 39687e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 39691da177e4SLinus Torvalds return -EPERM; 39701da177e4SLinus Torvalds 39711da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 39721da177e4SLinus Torvalds if (error) 39731da177e4SLinus Torvalds return error; 39741da177e4SLinus Torvalds 39757e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 3976aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 3977f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 3978aae8a97dSAneesh Kumar K.V error = -ENOENT; 39798de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 39808de52778SAl Viro error = -EMLINK; 3981146a8595SJ. Bruce Fields else { 3982146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 3983146a8595SJ. Bruce Fields if (!error) 39841da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 3985146a8595SJ. Bruce Fields } 3986f4e0c30cSAl Viro 3987f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 3988f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3989f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 3990f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3991f4e0c30cSAl Viro } 39927e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 3993e31e14ecSStephen Smalley if (!error) 39947e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 39951da177e4SLinus Torvalds return error; 39961da177e4SLinus Torvalds } 39974d359507SAl Viro EXPORT_SYMBOL(vfs_link); 39981da177e4SLinus Torvalds 39991da177e4SLinus Torvalds /* 40001da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 40011da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 40021da177e4SLinus Torvalds * newname. --KAB 40031da177e4SLinus Torvalds * 40041da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 40051da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 40061da177e4SLinus Torvalds * and other special files. --ADM 40071da177e4SLinus Torvalds */ 40082e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 40092e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 40101da177e4SLinus Torvalds { 40111da177e4SLinus Torvalds struct dentry *new_dentry; 4012dae6ad8fSAl Viro struct path old_path, new_path; 4013146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 401411a7b371SAneesh Kumar K.V int how = 0; 40151da177e4SLinus Torvalds int error; 40161da177e4SLinus Torvalds 401711a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4018c04030e1SUlrich Drepper return -EINVAL; 401911a7b371SAneesh Kumar K.V /* 4020f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4021f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4022f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 402311a7b371SAneesh Kumar K.V */ 4024f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4025f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4026f0cc6ffbSLinus Torvalds return -ENOENT; 402711a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4028f0cc6ffbSLinus Torvalds } 4029c04030e1SUlrich Drepper 403011a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 403111a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4032442e31caSJeff Layton retry: 403311a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 40341da177e4SLinus Torvalds if (error) 40352ad94ae6SAl Viro return error; 40362ad94ae6SAl Viro 4037442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4038442e31caSJeff Layton (how & LOOKUP_REVAL)); 40391da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 40406902d925SDave Hansen if (IS_ERR(new_dentry)) 4041dae6ad8fSAl Viro goto out; 4042dae6ad8fSAl Viro 4043dae6ad8fSAl Viro error = -EXDEV; 4044dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4045dae6ad8fSAl Viro goto out_dput; 4046800179c9SKees Cook error = may_linkat(&old_path); 4047800179c9SKees Cook if (unlikely(error)) 4048800179c9SKees Cook goto out_dput; 4049dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4050be6d3e56SKentaro Takeda if (error) 4051a8104a9fSAl Viro goto out_dput; 4052146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 405375c3f29dSDave Hansen out_dput: 4054921a1650SAl Viro done_path_create(&new_path, new_dentry); 4055146a8595SJ. Bruce Fields if (delegated_inode) { 4056146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4057d22e6338SOleg Drokin if (!error) { 4058d22e6338SOleg Drokin path_put(&old_path); 4059146a8595SJ. Bruce Fields goto retry; 4060146a8595SJ. Bruce Fields } 4061d22e6338SOleg Drokin } 4062442e31caSJeff Layton if (retry_estale(error, how)) { 4063d22e6338SOleg Drokin path_put(&old_path); 4064442e31caSJeff Layton how |= LOOKUP_REVAL; 4065442e31caSJeff Layton goto retry; 4066442e31caSJeff Layton } 40671da177e4SLinus Torvalds out: 40682d8f3038SAl Viro path_put(&old_path); 40691da177e4SLinus Torvalds 40701da177e4SLinus Torvalds return error; 40711da177e4SLinus Torvalds } 40721da177e4SLinus Torvalds 40733480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 40745590ff0dSUlrich Drepper { 4075c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 40765590ff0dSUlrich Drepper } 40775590ff0dSUlrich Drepper 4078bc27027aSMiklos Szeredi /** 4079bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4080bc27027aSMiklos Szeredi * @old_dir: parent of source 4081bc27027aSMiklos Szeredi * @old_dentry: source 4082bc27027aSMiklos Szeredi * @new_dir: parent of destination 4083bc27027aSMiklos Szeredi * @new_dentry: destination 4084bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4085520c8b16SMiklos Szeredi * @flags: rename flags 4086bc27027aSMiklos Szeredi * 4087bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4088bc27027aSMiklos Szeredi * 4089bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4090bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4091bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4092bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4093bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4094bc27027aSMiklos Szeredi * so. 4095bc27027aSMiklos Szeredi * 4096bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4097bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4098bc27027aSMiklos Szeredi * to be NFS exported. 4099bc27027aSMiklos Szeredi * 41001da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 41011da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 41021da177e4SLinus Torvalds * Problems: 4103d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 41041da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 41051da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4106a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 41071da177e4SLinus Torvalds * story. 41086cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 41096cedba89SJ. Bruce Fields * and source (if it is not a directory). 41101b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 41111da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 41121da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4113a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 41141da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 41151da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 41161da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4117a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 41181da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 41191da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 41201da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4121e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 41221b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 41231da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4124c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 41251da177e4SLinus Torvalds * locking]. 41261da177e4SLinus Torvalds */ 41271da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 41288e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4129520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 41301da177e4SLinus Torvalds { 41311da177e4SLinus Torvalds int error; 4132bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 413359b0df21SEric Paris const unsigned char *old_name; 4134bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4135bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4136da1ce067SMiklos Szeredi bool new_is_dir = false; 4137da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 41381da177e4SLinus Torvalds 4139bc27027aSMiklos Szeredi if (source == target) 41401da177e4SLinus Torvalds return 0; 41411da177e4SLinus Torvalds 41421da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 41431da177e4SLinus Torvalds if (error) 41441da177e4SLinus Torvalds return error; 41451da177e4SLinus Torvalds 4146da1ce067SMiklos Szeredi if (!target) { 4147a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4148da1ce067SMiklos Szeredi } else { 4149da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4150da1ce067SMiklos Szeredi 4151da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 41521da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4153da1ce067SMiklos Szeredi else 4154da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4155da1ce067SMiklos Szeredi } 41561da177e4SLinus Torvalds if (error) 41571da177e4SLinus Torvalds return error; 41581da177e4SLinus Torvalds 41597177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 41601da177e4SLinus Torvalds return -EPERM; 41611da177e4SLinus Torvalds 4162520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4163520c8b16SMiklos Szeredi return -EINVAL; 4164520c8b16SMiklos Szeredi 4165bc27027aSMiklos Szeredi /* 4166bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4167bc27027aSMiklos Szeredi * we'll need to flip '..'. 4168bc27027aSMiklos Szeredi */ 4169da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4170da1ce067SMiklos Szeredi if (is_dir) { 4171bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4172bc27027aSMiklos Szeredi if (error) 4173bc27027aSMiklos Szeredi return error; 4174bc27027aSMiklos Szeredi } 4175da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4176da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4177da1ce067SMiklos Szeredi if (error) 4178da1ce067SMiklos Szeredi return error; 4179da1ce067SMiklos Szeredi } 4180da1ce067SMiklos Szeredi } 41810eeca283SRobert Love 41820b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 41830b3974ebSMiklos Szeredi flags); 4184bc27027aSMiklos Szeredi if (error) 4185bc27027aSMiklos Szeredi return error; 4186bc27027aSMiklos Szeredi 4187bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4188bc27027aSMiklos Szeredi dget(new_dentry); 4189da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4190bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4191bc27027aSMiklos Szeredi else if (target) 4192bc27027aSMiklos Szeredi mutex_lock(&target->i_mutex); 4193bc27027aSMiklos Szeredi 4194bc27027aSMiklos Szeredi error = -EBUSY; 41957af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4196bc27027aSMiklos Szeredi goto out; 4197bc27027aSMiklos Szeredi 4198da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4199bc27027aSMiklos Szeredi error = -EMLINK; 4200da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4201bc27027aSMiklos Szeredi goto out; 4202da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4203da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4204da1ce067SMiklos Szeredi goto out; 4205da1ce067SMiklos Szeredi } 4206da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4207bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4208da1ce067SMiklos Szeredi if (!is_dir) { 4209bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4210bc27027aSMiklos Szeredi if (error) 4211bc27027aSMiklos Szeredi goto out; 4212da1ce067SMiklos Szeredi } 4213da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4214bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4215bc27027aSMiklos Szeredi if (error) 4216bc27027aSMiklos Szeredi goto out; 4217bc27027aSMiklos Szeredi } 42187177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4219520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4220520c8b16SMiklos Szeredi new_dir, new_dentry); 4221520c8b16SMiklos Szeredi } else { 42227177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4223520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4224520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4225520c8b16SMiklos Szeredi } 4226bc27027aSMiklos Szeredi if (error) 4227bc27027aSMiklos Szeredi goto out; 4228bc27027aSMiklos Szeredi 4229da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 42301da177e4SLinus Torvalds if (is_dir) 4231bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4232bc27027aSMiklos Szeredi dont_mount(new_dentry); 42338ed936b5SEric W. Biederman detach_mounts(new_dentry); 4234bc27027aSMiklos Szeredi } 4235da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4236da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4237bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4238da1ce067SMiklos Szeredi else 4239da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4240da1ce067SMiklos Szeredi } 4241bc27027aSMiklos Szeredi out: 4242da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4243bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4244bc27027aSMiklos Szeredi else if (target) 4245bc27027aSMiklos Szeredi mutex_unlock(&target->i_mutex); 4246bc27027aSMiklos Szeredi dput(new_dentry); 4247da1ce067SMiklos Szeredi if (!error) { 4248123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4249da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4250da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4251da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4252da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4253da1ce067SMiklos Szeredi } 4254da1ce067SMiklos Szeredi } 42550eeca283SRobert Love fsnotify_oldname_free(old_name); 42560eeca283SRobert Love 42571da177e4SLinus Torvalds return error; 42581da177e4SLinus Torvalds } 42594d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 42601da177e4SLinus Torvalds 4261520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4262520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 42631da177e4SLinus Torvalds { 42641da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 42651da177e4SLinus Torvalds struct dentry *trap; 4266f5beed75SAl Viro struct path old_path, new_path; 4267f5beed75SAl Viro struct qstr old_last, new_last; 4268f5beed75SAl Viro int old_type, new_type; 42698e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 427091a27b2aSJeff Layton struct filename *from; 427191a27b2aSJeff Layton struct filename *to; 4272f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4273c6a94284SJeff Layton bool should_retry = false; 42742ad94ae6SAl Viro int error; 4275520c8b16SMiklos Szeredi 42760d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4277da1ce067SMiklos Szeredi return -EINVAL; 4278da1ce067SMiklos Szeredi 42790d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 42800d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4281520c8b16SMiklos Szeredi return -EINVAL; 4282520c8b16SMiklos Szeredi 42830d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 42840d7a8555SMiklos Szeredi return -EPERM; 42850d7a8555SMiklos Szeredi 4286f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4287f5beed75SAl Viro target_flags = 0; 4288f5beed75SAl Viro 4289c6a94284SJeff Layton retry: 4290f5beed75SAl Viro from = user_path_parent(olddfd, oldname, 4291f5beed75SAl Viro &old_path, &old_last, &old_type, lookup_flags); 429291a27b2aSJeff Layton if (IS_ERR(from)) { 429391a27b2aSJeff Layton error = PTR_ERR(from); 42941da177e4SLinus Torvalds goto exit; 429591a27b2aSJeff Layton } 42961da177e4SLinus Torvalds 4297f5beed75SAl Viro to = user_path_parent(newdfd, newname, 4298f5beed75SAl Viro &new_path, &new_last, &new_type, lookup_flags); 429991a27b2aSJeff Layton if (IS_ERR(to)) { 430091a27b2aSJeff Layton error = PTR_ERR(to); 43011da177e4SLinus Torvalds goto exit1; 430291a27b2aSJeff Layton } 43031da177e4SLinus Torvalds 43041da177e4SLinus Torvalds error = -EXDEV; 4305f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 43061da177e4SLinus Torvalds goto exit2; 43071da177e4SLinus Torvalds 43081da177e4SLinus Torvalds error = -EBUSY; 4309f5beed75SAl Viro if (old_type != LAST_NORM) 43101da177e4SLinus Torvalds goto exit2; 43111da177e4SLinus Torvalds 43120a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 43130a7c3937SMiklos Szeredi error = -EEXIST; 4314f5beed75SAl Viro if (new_type != LAST_NORM) 43151da177e4SLinus Torvalds goto exit2; 43161da177e4SLinus Torvalds 4317f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4318c30dabfeSJan Kara if (error) 4319c30dabfeSJan Kara goto exit2; 4320c30dabfeSJan Kara 43218e6d782cSJ. Bruce Fields retry_deleg: 4322f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 43231da177e4SLinus Torvalds 4324f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 43251da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 43261da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 43271da177e4SLinus Torvalds goto exit3; 43281da177e4SLinus Torvalds /* source must exist */ 43291da177e4SLinus Torvalds error = -ENOENT; 4330b18825a7SDavid Howells if (d_is_negative(old_dentry)) 43311da177e4SLinus Torvalds goto exit4; 4332f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 43331da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 43341da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 43351da177e4SLinus Torvalds goto exit4; 43360a7c3937SMiklos Szeredi error = -EEXIST; 43370a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 43380a7c3937SMiklos Szeredi goto exit5; 4339da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4340da1ce067SMiklos Szeredi error = -ENOENT; 4341da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4342da1ce067SMiklos Szeredi goto exit5; 4343da1ce067SMiklos Szeredi 4344da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4345da1ce067SMiklos Szeredi error = -ENOTDIR; 4346f5beed75SAl Viro if (new_last.name[new_last.len]) 4347da1ce067SMiklos Szeredi goto exit5; 4348da1ce067SMiklos Szeredi } 4349da1ce067SMiklos Szeredi } 43500a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 43510a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 43520a7c3937SMiklos Szeredi error = -ENOTDIR; 4353f5beed75SAl Viro if (old_last.name[old_last.len]) 43540a7c3937SMiklos Szeredi goto exit5; 4355f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 43560a7c3937SMiklos Szeredi goto exit5; 43570a7c3937SMiklos Szeredi } 43580a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 43590a7c3937SMiklos Szeredi error = -EINVAL; 43600a7c3937SMiklos Szeredi if (old_dentry == trap) 43610a7c3937SMiklos Szeredi goto exit5; 43621da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4363da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43641da177e4SLinus Torvalds error = -ENOTEMPTY; 43651da177e4SLinus Torvalds if (new_dentry == trap) 43661da177e4SLinus Torvalds goto exit5; 43671da177e4SLinus Torvalds 4368f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4369f5beed75SAl Viro &new_path, new_dentry, flags); 4370be6d3e56SKentaro Takeda if (error) 4371c30dabfeSJan Kara goto exit5; 4372f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4373f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4374520c8b16SMiklos Szeredi &delegated_inode, flags); 43751da177e4SLinus Torvalds exit5: 43761da177e4SLinus Torvalds dput(new_dentry); 43771da177e4SLinus Torvalds exit4: 43781da177e4SLinus Torvalds dput(old_dentry); 43791da177e4SLinus Torvalds exit3: 4380f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 43818e6d782cSJ. Bruce Fields if (delegated_inode) { 43828e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 43838e6d782cSJ. Bruce Fields if (!error) 43848e6d782cSJ. Bruce Fields goto retry_deleg; 43858e6d782cSJ. Bruce Fields } 4386f5beed75SAl Viro mnt_drop_write(old_path.mnt); 43871da177e4SLinus Torvalds exit2: 4388c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4389c6a94284SJeff Layton should_retry = true; 4390f5beed75SAl Viro path_put(&new_path); 43912ad94ae6SAl Viro putname(to); 43921da177e4SLinus Torvalds exit1: 4393f5beed75SAl Viro path_put(&old_path); 43941da177e4SLinus Torvalds putname(from); 4395c6a94284SJeff Layton if (should_retry) { 4396c6a94284SJeff Layton should_retry = false; 4397c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4398c6a94284SJeff Layton goto retry; 4399c6a94284SJeff Layton } 44002ad94ae6SAl Viro exit: 44011da177e4SLinus Torvalds return error; 44021da177e4SLinus Torvalds } 44031da177e4SLinus Torvalds 4404520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4405520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4406520c8b16SMiklos Szeredi { 4407520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4408520c8b16SMiklos Szeredi } 4409520c8b16SMiklos Szeredi 4410a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 44115590ff0dSUlrich Drepper { 4412520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 44135590ff0dSUlrich Drepper } 44145590ff0dSUlrich Drepper 4415787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4416787fb6bcSMiklos Szeredi { 4417787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4418787fb6bcSMiklos Szeredi if (error) 4419787fb6bcSMiklos Szeredi return error; 4420787fb6bcSMiklos Szeredi 4421787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4422787fb6bcSMiklos Szeredi return -EPERM; 4423787fb6bcSMiklos Szeredi 4424787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4425787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4426787fb6bcSMiklos Szeredi } 4427787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4428787fb6bcSMiklos Szeredi 44295d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 44301da177e4SLinus Torvalds { 44315d826c84SAl Viro int len = PTR_ERR(link); 44321da177e4SLinus Torvalds if (IS_ERR(link)) 44331da177e4SLinus Torvalds goto out; 44341da177e4SLinus Torvalds 44351da177e4SLinus Torvalds len = strlen(link); 44361da177e4SLinus Torvalds if (len > (unsigned) buflen) 44371da177e4SLinus Torvalds len = buflen; 44381da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 44391da177e4SLinus Torvalds len = -EFAULT; 44401da177e4SLinus Torvalds out: 44411da177e4SLinus Torvalds return len; 44421da177e4SLinus Torvalds } 44435d826c84SAl Viro EXPORT_SYMBOL(readlink_copy); 44441da177e4SLinus Torvalds 44451da177e4SLinus Torvalds /* 44461da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 44471da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 44481da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 44491da177e4SLinus Torvalds */ 44501da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44511da177e4SLinus Torvalds { 4452cc314eefSLinus Torvalds void *cookie; 4453d4dee48bSAl Viro const char *link = dentry->d_inode->i_link; 4454694a1764SMarcin Slusarz int res; 4455cc314eefSLinus Torvalds 4456d4dee48bSAl Viro if (!link) { 44576e77137bSAl Viro link = dentry->d_inode->i_op->follow_link(dentry, &cookie); 4458680baacbSAl Viro if (IS_ERR(link)) 4459680baacbSAl Viro return PTR_ERR(link); 4460d4dee48bSAl Viro } 4461680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 44626e77137bSAl Viro if (dentry->d_inode->i_op->put_link) 4463680baacbSAl Viro dentry->d_inode->i_op->put_link(dentry, cookie); 4464694a1764SMarcin Slusarz return res; 44651da177e4SLinus Torvalds } 44664d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 44671da177e4SLinus Torvalds 44681da177e4SLinus Torvalds /* get the link contents into pagecache */ 44691da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 44701da177e4SLinus Torvalds { 4471ebd09abbSDuane Griffin char *kaddr; 44721da177e4SLinus Torvalds struct page *page; 44731da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 4474090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 44751da177e4SLinus Torvalds if (IS_ERR(page)) 44766fe6900eSNick Piggin return (char*)page; 44771da177e4SLinus Torvalds *ppage = page; 4478ebd09abbSDuane Griffin kaddr = kmap(page); 4479ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 4480ebd09abbSDuane Griffin return kaddr; 44811da177e4SLinus Torvalds } 44821da177e4SLinus Torvalds 44831da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44841da177e4SLinus Torvalds { 44851da177e4SLinus Torvalds struct page *page = NULL; 44865d826c84SAl Viro int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); 44871da177e4SLinus Torvalds if (page) { 44881da177e4SLinus Torvalds kunmap(page); 44891da177e4SLinus Torvalds page_cache_release(page); 44901da177e4SLinus Torvalds } 44911da177e4SLinus Torvalds return res; 44921da177e4SLinus Torvalds } 44934d359507SAl Viro EXPORT_SYMBOL(page_readlink); 44941da177e4SLinus Torvalds 44956e77137bSAl Viro const char *page_follow_link_light(struct dentry *dentry, void **cookie) 44961da177e4SLinus Torvalds { 4497cc314eefSLinus Torvalds struct page *page = NULL; 4498680baacbSAl Viro char *res = page_getlink(dentry, &page); 4499680baacbSAl Viro if (!IS_ERR(res)) 4500680baacbSAl Viro *cookie = page; 4501680baacbSAl Viro return res; 45021da177e4SLinus Torvalds } 45034d359507SAl Viro EXPORT_SYMBOL(page_follow_link_light); 45041da177e4SLinus Torvalds 4505680baacbSAl Viro void page_put_link(struct dentry *dentry, void *cookie) 45061da177e4SLinus Torvalds { 4507cc314eefSLinus Torvalds struct page *page = cookie; 45081da177e4SLinus Torvalds kunmap(page); 45091da177e4SLinus Torvalds page_cache_release(page); 45101da177e4SLinus Torvalds } 45114d359507SAl Viro EXPORT_SYMBOL(page_put_link); 45121da177e4SLinus Torvalds 451354566b2cSNick Piggin /* 451454566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 451554566b2cSNick Piggin */ 451654566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 45171da177e4SLinus Torvalds { 45181da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 45190adb25d2SKirill Korotaev struct page *page; 4520afddba49SNick Piggin void *fsdata; 4521beb497abSDmitriy Monakhov int err; 45221da177e4SLinus Torvalds char *kaddr; 452354566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 452454566b2cSNick Piggin if (nofs) 452554566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 45261da177e4SLinus Torvalds 45277e53cac4SNeilBrown retry: 4528afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 452954566b2cSNick Piggin flags, &page, &fsdata); 45301da177e4SLinus Torvalds if (err) 4531afddba49SNick Piggin goto fail; 4532afddba49SNick Piggin 4533e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 45341da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 4535e8e3c3d6SCong Wang kunmap_atomic(kaddr); 4536afddba49SNick Piggin 4537afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4538afddba49SNick Piggin page, fsdata); 45391da177e4SLinus Torvalds if (err < 0) 45401da177e4SLinus Torvalds goto fail; 4541afddba49SNick Piggin if (err < len-1) 4542afddba49SNick Piggin goto retry; 4543afddba49SNick Piggin 45441da177e4SLinus Torvalds mark_inode_dirty(inode); 45451da177e4SLinus Torvalds return 0; 45461da177e4SLinus Torvalds fail: 45471da177e4SLinus Torvalds return err; 45481da177e4SLinus Torvalds } 45494d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 45501da177e4SLinus Torvalds 45510adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 45520adb25d2SKirill Korotaev { 45530adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 455454566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 45550adb25d2SKirill Korotaev } 45564d359507SAl Viro EXPORT_SYMBOL(page_symlink); 45570adb25d2SKirill Korotaev 455892e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 45591da177e4SLinus Torvalds .readlink = generic_readlink, 45601da177e4SLinus Torvalds .follow_link = page_follow_link_light, 45611da177e4SLinus Torvalds .put_link = page_put_link, 45621da177e4SLinus Torvalds }; 45631da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4564