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; 5029883d185SAl Viro unsigned seq, m_seq; 5031f55a6ecSAl Viro int last_type; 5041f55a6ecSAl Viro unsigned depth; 505756daf26SNeilBrown int total_link_count; 506697fc6caSAl Viro struct saved { 507697fc6caSAl Viro struct path link; 508697fc6caSAl Viro void *cookie; 509697fc6caSAl Viro const char *name; 510237d8b32SAl Viro struct inode *inode; 5110450b2d1SAl Viro unsigned seq; 512894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5139883d185SAl Viro struct filename *name; 5149883d185SAl Viro struct nameidata *saved; 5159883d185SAl Viro unsigned root_seq; 5169883d185SAl Viro int dfd; 5171f55a6ecSAl Viro }; 5181f55a6ecSAl Viro 5199883d185SAl Viro static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) 520894bc8c4SAl Viro { 521756daf26SNeilBrown struct nameidata *old = current->nameidata; 522756daf26SNeilBrown p->stack = p->internal; 523c8a53ee5SAl Viro p->dfd = dfd; 524c8a53ee5SAl Viro p->name = name; 525756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 5269883d185SAl Viro p->saved = old; 527756daf26SNeilBrown current->nameidata = p; 528894bc8c4SAl Viro } 529894bc8c4SAl Viro 5309883d185SAl Viro static void restore_nameidata(void) 531894bc8c4SAl Viro { 5329883d185SAl Viro struct nameidata *now = current->nameidata, *old = now->saved; 533756daf26SNeilBrown 534756daf26SNeilBrown current->nameidata = old; 535756daf26SNeilBrown if (old) 536756daf26SNeilBrown old->total_link_count = now->total_link_count; 537756daf26SNeilBrown if (now->stack != now->internal) { 538756daf26SNeilBrown kfree(now->stack); 539756daf26SNeilBrown now->stack = now->internal; 540894bc8c4SAl Viro } 541894bc8c4SAl Viro } 542894bc8c4SAl Viro 543894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 544894bc8c4SAl Viro { 545bc40aee0SAl Viro struct saved *p; 546bc40aee0SAl Viro 547bc40aee0SAl Viro if (nd->flags & LOOKUP_RCU) { 548bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 549bc40aee0SAl Viro GFP_ATOMIC); 550bc40aee0SAl Viro if (unlikely(!p)) 551bc40aee0SAl Viro return -ECHILD; 552bc40aee0SAl Viro } else { 553bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 554894bc8c4SAl Viro GFP_KERNEL); 555894bc8c4SAl Viro if (unlikely(!p)) 556894bc8c4SAl Viro return -ENOMEM; 557bc40aee0SAl Viro } 558894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 559894bc8c4SAl Viro nd->stack = p; 560894bc8c4SAl Viro return 0; 561894bc8c4SAl Viro } 562894bc8c4SAl Viro 563397d425dSEric W. Biederman /** 564397d425dSEric W. Biederman * path_connected - Verify that a path->dentry is below path->mnt.mnt_root 565397d425dSEric W. Biederman * @path: nameidate to verify 566397d425dSEric W. Biederman * 567397d425dSEric W. Biederman * Rename can sometimes move a file or directory outside of a bind 568397d425dSEric W. Biederman * mount, path_connected allows those cases to be detected. 569397d425dSEric W. Biederman */ 570397d425dSEric W. Biederman static bool path_connected(const struct path *path) 571397d425dSEric W. Biederman { 572397d425dSEric W. Biederman struct vfsmount *mnt = path->mnt; 573397d425dSEric W. Biederman 574397d425dSEric W. Biederman /* Only bind mounts can have disconnected paths */ 575397d425dSEric W. Biederman if (mnt->mnt_root == mnt->mnt_sb->s_root) 576397d425dSEric W. Biederman return true; 577397d425dSEric W. Biederman 578397d425dSEric W. Biederman return is_subdir(path->dentry, mnt->mnt_root); 579397d425dSEric W. Biederman } 580397d425dSEric W. Biederman 581894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 582894bc8c4SAl Viro { 583da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 584894bc8c4SAl Viro return 0; 585894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 586894bc8c4SAl Viro return 0; 587894bc8c4SAl Viro return __nd_alloc_stack(nd); 588894bc8c4SAl Viro } 589894bc8c4SAl Viro 5907973387aSAl Viro static void drop_links(struct nameidata *nd) 5917973387aSAl Viro { 5927973387aSAl Viro int i = nd->depth; 5937973387aSAl Viro while (i--) { 5947973387aSAl Viro struct saved *last = nd->stack + i; 5957973387aSAl Viro struct inode *inode = last->inode; 5967973387aSAl Viro if (last->cookie && inode->i_op->put_link) { 5977973387aSAl Viro inode->i_op->put_link(inode, last->cookie); 5987973387aSAl Viro last->cookie = NULL; 5997973387aSAl Viro } 6007973387aSAl Viro } 6017973387aSAl Viro } 6027973387aSAl Viro 6037973387aSAl Viro static void terminate_walk(struct nameidata *nd) 6047973387aSAl Viro { 6057973387aSAl Viro drop_links(nd); 6067973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 6077973387aSAl Viro int i; 6087973387aSAl Viro path_put(&nd->path); 6097973387aSAl Viro for (i = 0; i < nd->depth; i++) 6107973387aSAl Viro path_put(&nd->stack[i].link); 611102b8af2SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 612102b8af2SAl Viro path_put(&nd->root); 613102b8af2SAl Viro nd->root.mnt = NULL; 614102b8af2SAl Viro } 6157973387aSAl Viro } else { 6167973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 6177973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6187973387aSAl Viro nd->root.mnt = NULL; 6197973387aSAl Viro rcu_read_unlock(); 6207973387aSAl Viro } 6217973387aSAl Viro nd->depth = 0; 6227973387aSAl Viro } 6237973387aSAl Viro 6247973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 6257973387aSAl Viro static bool legitimize_path(struct nameidata *nd, 6267973387aSAl Viro struct path *path, unsigned seq) 6277973387aSAl Viro { 6287973387aSAl Viro int res = __legitimize_mnt(path->mnt, nd->m_seq); 6297973387aSAl Viro if (unlikely(res)) { 6307973387aSAl Viro if (res > 0) 6317973387aSAl Viro path->mnt = NULL; 6327973387aSAl Viro path->dentry = NULL; 6337973387aSAl Viro return false; 6347973387aSAl Viro } 6357973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 6367973387aSAl Viro path->dentry = NULL; 6377973387aSAl Viro return false; 6387973387aSAl Viro } 6397973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6407973387aSAl Viro } 6417973387aSAl Viro 6427973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6437973387aSAl Viro { 6447973387aSAl Viro int i; 6457973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6467973387aSAl Viro struct saved *last = nd->stack + i; 6477973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6487973387aSAl Viro drop_links(nd); 6497973387aSAl Viro nd->depth = i + 1; 6507973387aSAl Viro return false; 6517973387aSAl Viro } 6527973387aSAl Viro } 6537973387aSAl Viro return true; 6547973387aSAl Viro } 6557973387aSAl Viro 65619660af7SAl Viro /* 65731e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 65819660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 65919660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 66019660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 66119660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 66219660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 66319660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 66419660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 66531e6b01fSNick Piggin */ 66631e6b01fSNick Piggin 66731e6b01fSNick Piggin /** 66819660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 66919660af7SAl Viro * @nd: nameidata pathwalk data 67019660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 6716e9918b7SAl Viro * @seq: seq number to check dentry against 67239191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 67331e6b01fSNick Piggin * 67419660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 67519660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 67619660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 6777973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6787973387aSAl Viro * terminate_walk(). 67931e6b01fSNick Piggin */ 6806e9918b7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry, unsigned seq) 68131e6b01fSNick Piggin { 68231e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 68331e6b01fSNick Piggin 68431e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 685e5c832d5SLinus Torvalds 686e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6877973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6887973387aSAl Viro goto out2; 6897973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 6907973387aSAl Viro goto out2; 6917973387aSAl Viro if (unlikely(!lockref_get_not_dead(&parent->d_lockref))) 6927973387aSAl Viro goto out1; 69348a066e7SAl Viro 69415570086SLinus Torvalds /* 69515570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 69615570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 69715570086SLinus Torvalds * 69815570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 69915570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 70015570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 70115570086SLinus Torvalds * since we checked the sequence number of the parent after we got 70215570086SLinus Torvalds * the child sequence number. So we know the parent must still 70315570086SLinus Torvalds * be valid if the child sequence number is still valid. 70415570086SLinus Torvalds */ 70519660af7SAl Viro if (!dentry) { 706e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 707e5c832d5SLinus Torvalds goto out; 70819660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 70919660af7SAl Viro } else { 710e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 711e5c832d5SLinus Torvalds goto out; 7126e9918b7SAl Viro if (read_seqcount_retry(&dentry->d_seq, seq)) 713e5c832d5SLinus Torvalds goto drop_dentry; 71419660af7SAl Viro } 715e5c832d5SLinus Torvalds 716e5c832d5SLinus Torvalds /* 717e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 718e5c832d5SLinus Torvalds * still valid and get it if required. 719e5c832d5SLinus Torvalds */ 720e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 7215a8d87e8SAl Viro if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq))) { 7225a8d87e8SAl Viro rcu_read_unlock(); 7235a8d87e8SAl Viro dput(dentry); 7245a8d87e8SAl Viro return -ECHILD; 7257973387aSAl Viro } 72631e6b01fSNick Piggin } 72731e6b01fSNick Piggin 7288b61e74fSAl Viro rcu_read_unlock(); 72931e6b01fSNick Piggin return 0; 73019660af7SAl Viro 731e5c832d5SLinus Torvalds drop_dentry: 7328b61e74fSAl Viro rcu_read_unlock(); 733e5c832d5SLinus Torvalds dput(dentry); 734d0d27277SLinus Torvalds goto drop_root_mnt; 7357973387aSAl Viro out2: 7367973387aSAl Viro nd->path.mnt = NULL; 7377973387aSAl Viro out1: 7387973387aSAl Viro nd->path.dentry = NULL; 739e5c832d5SLinus Torvalds out: 7408b61e74fSAl Viro rcu_read_unlock(); 741d0d27277SLinus Torvalds drop_root_mnt: 742d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 743d0d27277SLinus Torvalds nd->root.mnt = NULL; 74431e6b01fSNick Piggin return -ECHILD; 74531e6b01fSNick Piggin } 74631e6b01fSNick Piggin 7477973387aSAl Viro static int unlazy_link(struct nameidata *nd, struct path *link, unsigned seq) 7487973387aSAl Viro { 7497973387aSAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 7507973387aSAl Viro drop_links(nd); 7517973387aSAl Viro nd->depth = 0; 7527973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 7537973387aSAl Viro nd->path.mnt = NULL; 7547973387aSAl Viro nd->path.dentry = NULL; 7557973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7567973387aSAl Viro nd->root.mnt = NULL; 7577973387aSAl Viro rcu_read_unlock(); 7587973387aSAl Viro } else if (likely(unlazy_walk(nd, NULL, 0)) == 0) { 7597973387aSAl Viro return 0; 7607973387aSAl Viro } 7617973387aSAl Viro path_put(link); 7627973387aSAl Viro return -ECHILD; 7637973387aSAl Viro } 7647973387aSAl Viro 7654ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 76634286d66SNick Piggin { 7674ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 76834286d66SNick Piggin } 76934286d66SNick Piggin 7709f1fafeeSAl Viro /** 7719f1fafeeSAl Viro * complete_walk - successful completion of path walk 7729f1fafeeSAl Viro * @nd: pointer nameidata 77339159de2SJeff Layton * 7749f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7759f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7769f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7779f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7789f1fafeeSAl Viro * need to drop nd->path. 77939159de2SJeff Layton */ 7809f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 78139159de2SJeff Layton { 78216c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 78339159de2SJeff Layton int status; 78439159de2SJeff Layton 7859f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 7869f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7879f1fafeeSAl Viro nd->root.mnt = NULL; 7886e9918b7SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 78948a066e7SAl Viro return -ECHILD; 79048a066e7SAl Viro } 7919f1fafeeSAl Viro 79216c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 79339159de2SJeff Layton return 0; 79439159de2SJeff Layton 795ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 79616c2cd71SAl Viro return 0; 79716c2cd71SAl Viro 798ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 79939159de2SJeff Layton if (status > 0) 80039159de2SJeff Layton return 0; 80139159de2SJeff Layton 80216c2cd71SAl Viro if (!status) 80339159de2SJeff Layton status = -ESTALE; 80416c2cd71SAl Viro 80539159de2SJeff Layton return status; 80639159de2SJeff Layton } 80739159de2SJeff Layton 80818d8c860SAl Viro static void set_root(struct nameidata *nd) 8092a737871SAl Viro { 810f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 8112a737871SAl Viro } 8122a737871SAl Viro 81306d7137eSAl Viro static void set_root_rcu(struct nameidata *nd) 81431e6b01fSNick Piggin { 81531e6b01fSNick Piggin struct fs_struct *fs = current->fs; 8168f47a016SAl Viro unsigned seq; 817c28cc364SNick Piggin 818c28cc364SNick Piggin do { 819c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 82031e6b01fSNick Piggin nd->root = fs->root; 8218f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 822c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 82331e6b01fSNick Piggin } 82431e6b01fSNick Piggin 8251d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 826051d3812SIan Kent { 827051d3812SIan Kent dput(path->dentry); 8284ac91378SJan Blunck if (path->mnt != nd->path.mnt) 829051d3812SIan Kent mntput(path->mnt); 830051d3812SIan Kent } 831051d3812SIan Kent 8327b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8337b9337aaSNick Piggin struct nameidata *nd) 834051d3812SIan Kent { 83531e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8364ac91378SJan Blunck dput(nd->path.dentry); 83731e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8384ac91378SJan Blunck mntput(nd->path.mnt); 8399a229683SHuang Shijie } 84031e6b01fSNick Piggin nd->path.mnt = path->mnt; 8414ac91378SJan Blunck nd->path.dentry = path->dentry; 842051d3812SIan Kent } 843051d3812SIan Kent 844b5fb63c1SChristoph Hellwig /* 845b5fb63c1SChristoph Hellwig * Helper to directly jump to a known parsed path from ->follow_link, 846b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 847b5fb63c1SChristoph Hellwig */ 8486e77137bSAl Viro void nd_jump_link(struct path *path) 849b5fb63c1SChristoph Hellwig { 8506e77137bSAl Viro struct nameidata *nd = current->nameidata; 851b5fb63c1SChristoph Hellwig path_put(&nd->path); 852b5fb63c1SChristoph Hellwig 853b5fb63c1SChristoph Hellwig nd->path = *path; 854b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 855b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 856b5fb63c1SChristoph Hellwig } 857b5fb63c1SChristoph Hellwig 858b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 859574197e0SAl Viro { 86021c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 861237d8b32SAl Viro struct inode *inode = last->inode; 862b9ff4429SAl Viro if (last->cookie && inode->i_op->put_link) 8635f2c4179SAl Viro inode->i_op->put_link(inode, last->cookie); 8646548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 865b9ff4429SAl Viro path_put(&last->link); 866574197e0SAl Viro } 867574197e0SAl Viro 868561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 869561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 870800179c9SKees Cook 871800179c9SKees Cook /** 872800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 87355852635SRandy Dunlap * @nd: nameidata pathwalk data 874800179c9SKees Cook * 875800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 876800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 877800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 878800179c9SKees Cook * processes from failing races against path names that may change out 879800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 880800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 881800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 882800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 883800179c9SKees Cook * 884800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 885800179c9SKees Cook */ 886fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 887800179c9SKees Cook { 888800179c9SKees Cook const struct inode *inode; 889800179c9SKees Cook const struct inode *parent; 890800179c9SKees Cook 891800179c9SKees Cook if (!sysctl_protected_symlinks) 892800179c9SKees Cook return 0; 893800179c9SKees Cook 894800179c9SKees Cook /* Allowed if owner and follower match. */ 895237d8b32SAl Viro inode = nd->stack[0].inode; 89681abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 897800179c9SKees Cook return 0; 898800179c9SKees Cook 899800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 900aa65fa35SAl Viro parent = nd->inode; 901800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 902800179c9SKees Cook return 0; 903800179c9SKees Cook 904800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 90581abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 906800179c9SKees Cook return 0; 907800179c9SKees Cook 90831956502SAl Viro if (nd->flags & LOOKUP_RCU) 90931956502SAl Viro return -ECHILD; 91031956502SAl Viro 9111cf2665bSAl Viro audit_log_link_denied("follow_link", &nd->stack[0].link); 912800179c9SKees Cook return -EACCES; 913800179c9SKees Cook } 914800179c9SKees Cook 915800179c9SKees Cook /** 916800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 917800179c9SKees Cook * @inode: the source inode to hardlink from 918800179c9SKees Cook * 919800179c9SKees Cook * Return false if at least one of the following conditions: 920800179c9SKees Cook * - inode is not a regular file 921800179c9SKees Cook * - inode is setuid 922800179c9SKees Cook * - inode is setgid and group-exec 923800179c9SKees Cook * - access failure for read and write 924800179c9SKees Cook * 925800179c9SKees Cook * Otherwise returns true. 926800179c9SKees Cook */ 927800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 928800179c9SKees Cook { 929800179c9SKees Cook umode_t mode = inode->i_mode; 930800179c9SKees Cook 931800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 932800179c9SKees Cook if (!S_ISREG(mode)) 933800179c9SKees Cook return false; 934800179c9SKees Cook 935800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 936800179c9SKees Cook if (mode & S_ISUID) 937800179c9SKees Cook return false; 938800179c9SKees Cook 939800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 940800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 941800179c9SKees Cook return false; 942800179c9SKees Cook 943800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 944800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 945800179c9SKees Cook return false; 946800179c9SKees Cook 947800179c9SKees Cook return true; 948800179c9SKees Cook } 949800179c9SKees Cook 950800179c9SKees Cook /** 951800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 952800179c9SKees Cook * @link: the source to hardlink from 953800179c9SKees Cook * 954800179c9SKees Cook * Block hardlink when all of: 955800179c9SKees Cook * - sysctl_protected_hardlinks enabled 956800179c9SKees Cook * - fsuid does not match inode 957800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 958f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 959800179c9SKees Cook * 960800179c9SKees Cook * Returns 0 if successful, -ve on error. 961800179c9SKees Cook */ 962800179c9SKees Cook static int may_linkat(struct path *link) 963800179c9SKees Cook { 964800179c9SKees Cook struct inode *inode; 965800179c9SKees Cook 966800179c9SKees Cook if (!sysctl_protected_hardlinks) 967800179c9SKees Cook return 0; 968800179c9SKees Cook 969800179c9SKees Cook inode = link->dentry->d_inode; 970800179c9SKees Cook 971800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 972800179c9SKees Cook * otherwise, it must be a safe source. 973800179c9SKees Cook */ 974f2ca3796SDirk Steinmetz if (inode_owner_or_capable(inode) || safe_hardlink_source(inode)) 975800179c9SKees Cook return 0; 976800179c9SKees Cook 977a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 978800179c9SKees Cook return -EPERM; 979800179c9SKees Cook } 980800179c9SKees Cook 9813b2e7f75SAl Viro static __always_inline 9823b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 9831da177e4SLinus Torvalds { 984ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 9851cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 986237d8b32SAl Viro struct inode *inode = last->inode; 9876d7b5aaeSAl Viro int error; 9880a959df5SAl Viro const char *res; 9891da177e4SLinus Torvalds 9908fa9dd24SNeilBrown if (!(nd->flags & LOOKUP_RCU)) { 9918fa9dd24SNeilBrown touch_atime(&last->link); 9928fa9dd24SNeilBrown cond_resched(); 9938fa9dd24SNeilBrown } else if (atime_needs_update(&last->link, inode)) { 9948fa9dd24SNeilBrown if (unlikely(unlazy_walk(nd, NULL, 0))) 9958fa9dd24SNeilBrown return ERR_PTR(-ECHILD); 9968fa9dd24SNeilBrown touch_atime(&last->link); 9978fa9dd24SNeilBrown } 9988fa9dd24SNeilBrown 999bda0be7aSNeilBrown error = security_inode_follow_link(dentry, inode, 1000bda0be7aSNeilBrown nd->flags & LOOKUP_RCU); 1001bda0be7aSNeilBrown if (unlikely(error)) 10026920a440SAl Viro return ERR_PTR(error); 100336f3b4f6SAl Viro 100486acdca1SAl Viro nd->last_type = LAST_BIND; 1005d4dee48bSAl Viro res = inode->i_link; 1006d4dee48bSAl Viro if (!res) { 10078c1b4566SAl Viro if (nd->flags & LOOKUP_RCU) { 10088c1b4566SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 10098c1b4566SAl Viro return ERR_PTR(-ECHILD); 10108c1b4566SAl Viro } 10116e77137bSAl Viro res = inode->i_op->follow_link(dentry, &last->cookie); 1012fab51e8aSAl Viro if (IS_ERR_OR_NULL(res)) { 10136920a440SAl Viro last->cookie = NULL; 1014fab51e8aSAl Viro return res; 10150a959df5SAl Viro } 1016fab51e8aSAl Viro } 1017fab51e8aSAl Viro if (*res == '/') { 10188c1b4566SAl Viro if (nd->flags & LOOKUP_RCU) { 10198f47a016SAl Viro struct dentry *d; 10208f47a016SAl Viro if (!nd->root.mnt) 10218f47a016SAl Viro set_root_rcu(nd); 10228f47a016SAl Viro nd->path = nd->root; 10238f47a016SAl Viro d = nd->path.dentry; 10248f47a016SAl Viro nd->inode = d->d_inode; 10258f47a016SAl Viro nd->seq = nd->root_seq; 10268f47a016SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 10278c1b4566SAl Viro return ERR_PTR(-ECHILD); 10288f47a016SAl Viro } else { 1029fab51e8aSAl Viro if (!nd->root.mnt) 1030fab51e8aSAl Viro set_root(nd); 1031fab51e8aSAl Viro path_put(&nd->path); 1032fab51e8aSAl Viro nd->path = nd->root; 1033fab51e8aSAl Viro path_get(&nd->root); 1034fab51e8aSAl Viro nd->inode = nd->path.dentry->d_inode; 10358f47a016SAl Viro } 1036fab51e8aSAl Viro nd->flags |= LOOKUP_JUMPED; 1037fab51e8aSAl Viro while (unlikely(*++res == '/')) 1038fab51e8aSAl Viro ; 1039fab51e8aSAl Viro } 1040fab51e8aSAl Viro if (!*res) 1041fab51e8aSAl Viro res = NULL; 10420a959df5SAl Viro return res; 10430a959df5SAl Viro } 10446d7b5aaeSAl Viro 1045f015f126SDavid Howells /* 1046f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1047f015f126SDavid Howells * 1048f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1049f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1050f015f126SDavid Howells * Up is towards /. 1051f015f126SDavid Howells * 1052f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1053f015f126SDavid Howells * root. 1054f015f126SDavid Howells */ 1055bab77ebfSAl Viro int follow_up(struct path *path) 10561da177e4SLinus Torvalds { 10570714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 10580714a533SAl Viro struct mount *parent; 10591da177e4SLinus Torvalds struct dentry *mountpoint; 106099b7db7bSNick Piggin 106148a066e7SAl Viro read_seqlock_excl(&mount_lock); 10620714a533SAl Viro parent = mnt->mnt_parent; 10633c0a6163SAl Viro if (parent == mnt) { 106448a066e7SAl Viro read_sequnlock_excl(&mount_lock); 10651da177e4SLinus Torvalds return 0; 10661da177e4SLinus Torvalds } 10670714a533SAl Viro mntget(&parent->mnt); 1068a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 106948a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1070bab77ebfSAl Viro dput(path->dentry); 1071bab77ebfSAl Viro path->dentry = mountpoint; 1072bab77ebfSAl Viro mntput(path->mnt); 10730714a533SAl Viro path->mnt = &parent->mnt; 10741da177e4SLinus Torvalds return 1; 10751da177e4SLinus Torvalds } 10764d359507SAl Viro EXPORT_SYMBOL(follow_up); 10771da177e4SLinus Torvalds 1078b5c84bf6SNick Piggin /* 10799875cf80SDavid Howells * Perform an automount 10809875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 10819875cf80SDavid Howells * were called with. 10821da177e4SLinus Torvalds */ 1083756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 10849875cf80SDavid Howells bool *need_mntput) 108531e6b01fSNick Piggin { 10869875cf80SDavid Howells struct vfsmount *mnt; 1087ea5b778aSDavid Howells int err; 10889875cf80SDavid Howells 10899875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 10909875cf80SDavid Howells return -EREMOTE; 10919875cf80SDavid Howells 10920ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 10930ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 10940ec26fd0SMiklos Szeredi * the name. 10950ec26fd0SMiklos Szeredi * 10960ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 10975a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 10980ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 10990ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 11000ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 11010ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 11025a30d8a2SDavid Howells */ 1103756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 1104d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 11055a30d8a2SDavid Howells path->dentry->d_inode) 11069875cf80SDavid Howells return -EISDIR; 11070ec26fd0SMiklos Szeredi 1108756daf26SNeilBrown nd->total_link_count++; 1109756daf26SNeilBrown if (nd->total_link_count >= 40) 11109875cf80SDavid Howells return -ELOOP; 11119875cf80SDavid Howells 11129875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 11139875cf80SDavid Howells if (IS_ERR(mnt)) { 11149875cf80SDavid Howells /* 11159875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 11169875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 11179875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 11189875cf80SDavid Howells * 11199875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 11209875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 11219875cf80SDavid Howells * the path is inaccessible and we should say so. 11229875cf80SDavid Howells */ 1123756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 11249875cf80SDavid Howells return -EREMOTE; 11259875cf80SDavid Howells return PTR_ERR(mnt); 112631e6b01fSNick Piggin } 1127ea5b778aSDavid Howells 11289875cf80SDavid Howells if (!mnt) /* mount collision */ 11299875cf80SDavid Howells return 0; 11309875cf80SDavid Howells 11318aef1884SAl Viro if (!*need_mntput) { 11328aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 11338aef1884SAl Viro mntget(path->mnt); 11348aef1884SAl Viro *need_mntput = true; 11358aef1884SAl Viro } 113619a167afSAl Viro err = finish_automount(mnt, path); 1137ea5b778aSDavid Howells 1138ea5b778aSDavid Howells switch (err) { 1139ea5b778aSDavid Howells case -EBUSY: 1140ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 114119a167afSAl Viro return 0; 1142ea5b778aSDavid Howells case 0: 11438aef1884SAl Viro path_put(path); 11449875cf80SDavid Howells path->mnt = mnt; 11459875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 11469875cf80SDavid Howells return 0; 114719a167afSAl Viro default: 114819a167afSAl Viro return err; 11499875cf80SDavid Howells } 115019a167afSAl Viro 1151ea5b778aSDavid Howells } 11529875cf80SDavid Howells 11539875cf80SDavid Howells /* 11549875cf80SDavid Howells * Handle a dentry that is managed in some way. 1155cc53ce53SDavid Howells * - Flagged for transit management (autofs) 11569875cf80SDavid Howells * - Flagged as mountpoint 11579875cf80SDavid Howells * - Flagged as automount point 11589875cf80SDavid Howells * 11599875cf80SDavid Howells * This may only be called in refwalk mode. 11609875cf80SDavid Howells * 11619875cf80SDavid Howells * Serialization is taken care of in namespace.c 11629875cf80SDavid Howells */ 1163756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 11649875cf80SDavid Howells { 11658aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 11669875cf80SDavid Howells unsigned managed; 11679875cf80SDavid Howells bool need_mntput = false; 11688aef1884SAl Viro int ret = 0; 11699875cf80SDavid Howells 11709875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 11719875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 11729875cf80SDavid Howells * the components of that value change under us */ 11739875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 11749875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 11759875cf80SDavid Howells unlikely(managed != 0)) { 1176cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1177cc53ce53SDavid Howells * being held. */ 1178cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1179cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1180cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 11811aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1182cc53ce53SDavid Howells if (ret < 0) 11838aef1884SAl Viro break; 1184cc53ce53SDavid Howells } 1185cc53ce53SDavid Howells 11869875cf80SDavid Howells /* Transit to a mounted filesystem. */ 11879875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 11889875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 11899875cf80SDavid Howells if (mounted) { 11909875cf80SDavid Howells dput(path->dentry); 11919875cf80SDavid Howells if (need_mntput) 1192463ffb2eSAl Viro mntput(path->mnt); 1193463ffb2eSAl Viro path->mnt = mounted; 1194463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 11959875cf80SDavid Howells need_mntput = true; 11969875cf80SDavid Howells continue; 1197463ffb2eSAl Viro } 1198463ffb2eSAl Viro 11999875cf80SDavid Howells /* Something is mounted on this dentry in another 12009875cf80SDavid Howells * namespace and/or whatever was mounted there in this 120148a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 120248a066e7SAl Viro * get it */ 12031da177e4SLinus Torvalds } 12049875cf80SDavid Howells 12059875cf80SDavid Howells /* Handle an automount point */ 12069875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1207756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 12089875cf80SDavid Howells if (ret < 0) 12098aef1884SAl Viro break; 12109875cf80SDavid Howells continue; 12119875cf80SDavid Howells } 12129875cf80SDavid Howells 12139875cf80SDavid Howells /* We didn't change the current path point */ 12149875cf80SDavid Howells break; 12159875cf80SDavid Howells } 12168aef1884SAl Viro 12178aef1884SAl Viro if (need_mntput && path->mnt == mnt) 12188aef1884SAl Viro mntput(path->mnt); 12198aef1884SAl Viro if (ret == -EISDIR) 12208aef1884SAl Viro ret = 0; 12218402752eSAl Viro if (need_mntput) 12228402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 12238402752eSAl Viro if (unlikely(ret < 0)) 12248402752eSAl Viro path_put_conditional(path, nd); 12258402752eSAl Viro return ret; 12261da177e4SLinus Torvalds } 12271da177e4SLinus Torvalds 1228cc53ce53SDavid Howells int follow_down_one(struct path *path) 12291da177e4SLinus Torvalds { 12301da177e4SLinus Torvalds struct vfsmount *mounted; 12311da177e4SLinus Torvalds 12321c755af4SAl Viro mounted = lookup_mnt(path); 12331da177e4SLinus Torvalds if (mounted) { 12349393bd07SAl Viro dput(path->dentry); 12359393bd07SAl Viro mntput(path->mnt); 12369393bd07SAl Viro path->mnt = mounted; 12379393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12381da177e4SLinus Torvalds return 1; 12391da177e4SLinus Torvalds } 12401da177e4SLinus Torvalds return 0; 12411da177e4SLinus Torvalds } 12424d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12431da177e4SLinus Torvalds 1244b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 124562a7375eSIan Kent { 1246b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1247b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 124862a7375eSIan Kent } 124962a7375eSIan Kent 12509875cf80SDavid Howells /* 1251287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1252287548e4SAl Viro * we meet a managed dentry that would need blocking. 12539875cf80SDavid Howells */ 12549875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1255254cf582SAl Viro struct inode **inode, unsigned *seqp) 12569875cf80SDavid Howells { 125762a7375eSIan Kent for (;;) { 1258c7105365SAl Viro struct mount *mounted; 125962a7375eSIan Kent /* 126062a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 126162a7375eSIan Kent * that wants to block transit. 126262a7375eSIan Kent */ 1263b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1264b8faf035SNeilBrown case -ECHILD: 1265b8faf035SNeilBrown default: 1266ab90911fSDavid Howells return false; 1267b8faf035SNeilBrown case -EISDIR: 1268b8faf035SNeilBrown return true; 1269b8faf035SNeilBrown case 0: 1270b8faf035SNeilBrown break; 1271b8faf035SNeilBrown } 127262a7375eSIan Kent 127362a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1274b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 127562a7375eSIan Kent 1276474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 12779875cf80SDavid Howells if (!mounted) 12789875cf80SDavid Howells break; 1279c7105365SAl Viro path->mnt = &mounted->mnt; 1280c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1281a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1282254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 128359430262SLinus Torvalds /* 128459430262SLinus Torvalds * Update the inode too. We don't need to re-check the 128559430262SLinus Torvalds * dentry sequence number here after this d_inode read, 128659430262SLinus Torvalds * because a mount-point is always pinned. 128759430262SLinus Torvalds */ 128859430262SLinus Torvalds *inode = path->dentry->d_inode; 12899875cf80SDavid Howells } 1290f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1291b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1292287548e4SAl Viro } 1293287548e4SAl Viro 129431e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 129531e6b01fSNick Piggin { 12964023bfc9SAl Viro struct inode *inode = nd->inode; 12977bd88377SAl Viro if (!nd->root.mnt) 129831e6b01fSNick Piggin set_root_rcu(nd); 129931e6b01fSNick Piggin 130031e6b01fSNick Piggin while (1) { 1301aed434adSAl Viro if (path_equal(&nd->path, &nd->root)) 130231e6b01fSNick Piggin break; 130331e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 130431e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 130531e6b01fSNick Piggin struct dentry *parent = old->d_parent; 130631e6b01fSNick Piggin unsigned seq; 130731e6b01fSNick Piggin 13084023bfc9SAl Viro inode = parent->d_inode; 130931e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 1310aed434adSAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 1311aed434adSAl Viro return -ECHILD; 131231e6b01fSNick Piggin nd->path.dentry = parent; 131331e6b01fSNick Piggin nd->seq = seq; 1314397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 1315397d425dSEric W. Biederman return -ENOENT; 131631e6b01fSNick Piggin break; 1317aed434adSAl Viro } else { 1318aed434adSAl Viro struct mount *mnt = real_mount(nd->path.mnt); 1319aed434adSAl Viro struct mount *mparent = mnt->mnt_parent; 1320aed434adSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1321aed434adSAl Viro struct inode *inode2 = mountpoint->d_inode; 1322aed434adSAl Viro unsigned seq = read_seqcount_begin(&mountpoint->d_seq); 1323aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1324aed434adSAl Viro return -ECHILD; 1325aed434adSAl Viro if (&mparent->mnt == nd->path.mnt) 132631e6b01fSNick Piggin break; 1327aed434adSAl Viro /* we know that mountpoint was pinned */ 1328aed434adSAl Viro nd->path.dentry = mountpoint; 1329aed434adSAl Viro nd->path.mnt = &mparent->mnt; 1330aed434adSAl Viro inode = inode2; 1331aed434adSAl Viro nd->seq = seq; 133231e6b01fSNick Piggin } 1333aed434adSAl Viro } 1334aed434adSAl Viro while (unlikely(d_mountpoint(nd->path.dentry))) { 1335b37199e6SAl Viro struct mount *mounted; 1336b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1337aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1338aed434adSAl Viro return -ECHILD; 1339b37199e6SAl Viro if (!mounted) 1340b37199e6SAl Viro break; 1341b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1342b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 13434023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1344b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1345b37199e6SAl Viro } 13464023bfc9SAl Viro nd->inode = inode; 134731e6b01fSNick Piggin return 0; 134831e6b01fSNick Piggin } 134931e6b01fSNick Piggin 13509875cf80SDavid Howells /* 1351cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1352cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1353cc53ce53SDavid Howells * caller is permitted to proceed or not. 1354cc53ce53SDavid Howells */ 13557cc90cc3SAl Viro int follow_down(struct path *path) 1356cc53ce53SDavid Howells { 1357cc53ce53SDavid Howells unsigned managed; 1358cc53ce53SDavid Howells int ret; 1359cc53ce53SDavid Howells 1360cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1361cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1362cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1363cc53ce53SDavid Howells * being held. 1364cc53ce53SDavid Howells * 1365cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1366cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1367cc53ce53SDavid Howells * other than its daemon the right to mount on its 1368cc53ce53SDavid Howells * superstructure. 1369cc53ce53SDavid Howells * 1370cc53ce53SDavid Howells * The filesystem may sleep at this point. 1371cc53ce53SDavid Howells */ 1372cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1373cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1374cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1375ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 13761aed3e42SAl Viro path->dentry, false); 1377cc53ce53SDavid Howells if (ret < 0) 1378cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1379cc53ce53SDavid Howells } 1380cc53ce53SDavid Howells 1381cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1382cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1383cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1384cc53ce53SDavid Howells if (!mounted) 1385cc53ce53SDavid Howells break; 1386cc53ce53SDavid Howells dput(path->dentry); 1387cc53ce53SDavid Howells mntput(path->mnt); 1388cc53ce53SDavid Howells path->mnt = mounted; 1389cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1390cc53ce53SDavid Howells continue; 1391cc53ce53SDavid Howells } 1392cc53ce53SDavid Howells 1393cc53ce53SDavid Howells /* Don't handle automount points here */ 1394cc53ce53SDavid Howells break; 1395cc53ce53SDavid Howells } 1396cc53ce53SDavid Howells return 0; 1397cc53ce53SDavid Howells } 13984d359507SAl Viro EXPORT_SYMBOL(follow_down); 1399cc53ce53SDavid Howells 1400cc53ce53SDavid Howells /* 14019875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 14029875cf80SDavid Howells */ 14039875cf80SDavid Howells static void follow_mount(struct path *path) 14049875cf80SDavid Howells { 14059875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 14069875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 14079875cf80SDavid Howells if (!mounted) 14089875cf80SDavid Howells break; 14099875cf80SDavid Howells dput(path->dentry); 14109875cf80SDavid Howells mntput(path->mnt); 14119875cf80SDavid Howells path->mnt = mounted; 14129875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 14139875cf80SDavid Howells } 14149875cf80SDavid Howells } 14159875cf80SDavid Howells 1416397d425dSEric W. Biederman static int follow_dotdot(struct nameidata *nd) 14171da177e4SLinus Torvalds { 14187bd88377SAl Viro if (!nd->root.mnt) 14192a737871SAl Viro set_root(nd); 1420e518ddb7SAndreas Mohr 14211da177e4SLinus Torvalds while(1) { 14224ac91378SJan Blunck struct dentry *old = nd->path.dentry; 14231da177e4SLinus Torvalds 14242a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 14252a737871SAl Viro nd->path.mnt == nd->root.mnt) { 14261da177e4SLinus Torvalds break; 14271da177e4SLinus Torvalds } 14284ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 14293088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 14303088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 14311da177e4SLinus Torvalds dput(old); 1432397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 1433397d425dSEric W. Biederman return -ENOENT; 14341da177e4SLinus Torvalds break; 14351da177e4SLinus Torvalds } 14363088dd70SAl Viro if (!follow_up(&nd->path)) 14371da177e4SLinus Torvalds break; 14381da177e4SLinus Torvalds } 143979ed0226SAl Viro follow_mount(&nd->path); 144031e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 1441397d425dSEric W. Biederman return 0; 14421da177e4SLinus Torvalds } 14431da177e4SLinus Torvalds 14441da177e4SLinus Torvalds /* 1445bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1446bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1447bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1448bad61189SMiklos Szeredi * 1449bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1450baa03890SNick Piggin */ 1451bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1452201f956eSAl Viro unsigned int flags, bool *need_lookup) 1453baa03890SNick Piggin { 1454baa03890SNick Piggin struct dentry *dentry; 1455bad61189SMiklos Szeredi int error; 1456baa03890SNick Piggin 1457bad61189SMiklos Szeredi *need_lookup = false; 1458bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1459bad61189SMiklos Szeredi if (dentry) { 146039e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1461201f956eSAl Viro error = d_revalidate(dentry, flags); 1462bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1463bad61189SMiklos Szeredi if (error < 0) { 1464bad61189SMiklos Szeredi dput(dentry); 1465bad61189SMiklos Szeredi return ERR_PTR(error); 14665542aa2fSEric W. Biederman } else { 14675542aa2fSEric W. Biederman d_invalidate(dentry); 1468bad61189SMiklos Szeredi dput(dentry); 1469bad61189SMiklos Szeredi dentry = NULL; 1470bad61189SMiklos Szeredi } 1471bad61189SMiklos Szeredi } 1472bad61189SMiklos Szeredi } 1473bad61189SMiklos Szeredi } 1474baa03890SNick Piggin 1475bad61189SMiklos Szeredi if (!dentry) { 1476bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1477baa03890SNick Piggin if (unlikely(!dentry)) 1478baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1479baa03890SNick Piggin 1480bad61189SMiklos Szeredi *need_lookup = true; 1481baa03890SNick Piggin } 1482baa03890SNick Piggin return dentry; 1483baa03890SNick Piggin } 1484baa03890SNick Piggin 1485baa03890SNick Piggin /* 148613a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 148713a2c3beSJ. Bruce Fields * unhashed. 1488bad61189SMiklos Szeredi * 1489bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 149044396f4bSJosef Bacik */ 1491bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 149272bd866aSAl Viro unsigned int flags) 149344396f4bSJosef Bacik { 149444396f4bSJosef Bacik struct dentry *old; 149544396f4bSJosef Bacik 149644396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1497bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1498e188dc02SMiklos Szeredi dput(dentry); 149944396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1500e188dc02SMiklos Szeredi } 150144396f4bSJosef Bacik 150272bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 150344396f4bSJosef Bacik if (unlikely(old)) { 150444396f4bSJosef Bacik dput(dentry); 150544396f4bSJosef Bacik dentry = old; 150644396f4bSJosef Bacik } 150744396f4bSJosef Bacik return dentry; 150844396f4bSJosef Bacik } 150944396f4bSJosef Bacik 1510a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 151172bd866aSAl Viro struct dentry *base, unsigned int flags) 1512a3255546SAl Viro { 1513bad61189SMiklos Szeredi bool need_lookup; 1514a3255546SAl Viro struct dentry *dentry; 1515a3255546SAl Viro 151672bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1517bad61189SMiklos Szeredi if (!need_lookup) 1518a3255546SAl Viro return dentry; 1519bad61189SMiklos Szeredi 152072bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1521a3255546SAl Viro } 1522a3255546SAl Viro 152344396f4bSJosef Bacik /* 15241da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 15251da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 15261da177e4SLinus Torvalds * It _is_ time-critical. 15271da177e4SLinus Torvalds */ 1528e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 1529254cf582SAl Viro struct path *path, struct inode **inode, 1530254cf582SAl Viro unsigned *seqp) 15311da177e4SLinus Torvalds { 15324ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 153331e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 15345a18fff2SAl Viro int need_reval = 1; 15355a18fff2SAl Viro int status = 1; 15369875cf80SDavid Howells int err; 15379875cf80SDavid Howells 15383cac260aSAl Viro /* 1539b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1540b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1541b04f784eSNick Piggin * do the non-racy lookup, below. 1542b04f784eSNick Piggin */ 154331e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 154431e6b01fSNick Piggin unsigned seq; 1545766c4cbfSAl Viro bool negative; 1546da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15475a18fff2SAl Viro if (!dentry) 15485a18fff2SAl Viro goto unlazy; 15495a18fff2SAl Viro 155012f8ad4bSLinus Torvalds /* 155112f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 155212f8ad4bSLinus Torvalds * the dentry name information from lookup. 155312f8ad4bSLinus Torvalds */ 155463afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1555766c4cbfSAl Viro negative = d_is_negative(dentry); 155612f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 155712f8ad4bSLinus Torvalds return -ECHILD; 1558766c4cbfSAl Viro if (negative) 1559766c4cbfSAl Viro return -ENOENT; 156012f8ad4bSLinus Torvalds 156112f8ad4bSLinus Torvalds /* 156212f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 156312f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 156412f8ad4bSLinus Torvalds * 156512f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 156612f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 156712f8ad4bSLinus Torvalds */ 156831e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 156931e6b01fSNick Piggin return -ECHILD; 15705a18fff2SAl Viro 1571254cf582SAl Viro *seqp = seq; 157224643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 15734ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15745a18fff2SAl Viro if (unlikely(status <= 0)) { 15755a18fff2SAl Viro if (status != -ECHILD) 15765a18fff2SAl Viro need_reval = 0; 15775a18fff2SAl Viro goto unlazy; 15785a18fff2SAl Viro } 157924643087SAl Viro } 158031e6b01fSNick Piggin path->mnt = mnt; 158131e6b01fSNick Piggin path->dentry = dentry; 1582254cf582SAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 15839875cf80SDavid Howells return 0; 15845a18fff2SAl Viro unlazy: 1585254cf582SAl Viro if (unlazy_walk(nd, dentry, seq)) 15865a18fff2SAl Viro return -ECHILD; 15875a18fff2SAl Viro } else { 1588e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 158924643087SAl Viro } 15905a18fff2SAl Viro 159181e6f520SAl Viro if (unlikely(!dentry)) 159281e6f520SAl Viro goto need_lookup; 15935a18fff2SAl Viro 15945a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 15954ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15965a18fff2SAl Viro if (unlikely(status <= 0)) { 15975a18fff2SAl Viro if (status < 0) { 15985a18fff2SAl Viro dput(dentry); 15995a18fff2SAl Viro return status; 16005a18fff2SAl Viro } 16015542aa2fSEric W. Biederman d_invalidate(dentry); 16025a18fff2SAl Viro dput(dentry); 160381e6f520SAl Viro goto need_lookup; 16045a18fff2SAl Viro } 1605697f514dSMiklos Szeredi 1606766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1607766c4cbfSAl Viro dput(dentry); 1608766c4cbfSAl Viro return -ENOENT; 1609766c4cbfSAl Viro } 16101da177e4SLinus Torvalds path->mnt = mnt; 16111da177e4SLinus Torvalds path->dentry = dentry; 1612756daf26SNeilBrown err = follow_managed(path, nd); 16138402752eSAl Viro if (likely(!err)) 161463afdfc7SDavid Howells *inode = d_backing_inode(path->dentry); 16158402752eSAl Viro return err; 161681e6f520SAl Viro 161781e6f520SAl Viro need_lookup: 1618697f514dSMiklos Szeredi return 1; 1619697f514dSMiklos Szeredi } 1620697f514dSMiklos Szeredi 1621697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1622cc2a5271SAl Viro static int lookup_slow(struct nameidata *nd, struct path *path) 1623697f514dSMiklos Szeredi { 1624697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1625697f514dSMiklos Szeredi 1626697f514dSMiklos Szeredi parent = nd->path.dentry; 162781e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 162881e6f520SAl Viro 162981e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 1630cc2a5271SAl Viro dentry = __lookup_hash(&nd->last, parent, nd->flags); 163181e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 163281e6f520SAl Viro if (IS_ERR(dentry)) 163381e6f520SAl Viro return PTR_ERR(dentry); 1634697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1635697f514dSMiklos Szeredi path->dentry = dentry; 16368402752eSAl Viro return follow_managed(path, nd); 16371da177e4SLinus Torvalds } 16381da177e4SLinus Torvalds 163952094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 164052094c8aSAl Viro { 164152094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16424ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 164352094c8aSAl Viro if (err != -ECHILD) 164452094c8aSAl Viro return err; 16456e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 164652094c8aSAl Viro return -ECHILD; 164752094c8aSAl Viro } 16484ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 164952094c8aSAl Viro } 165052094c8aSAl Viro 16519856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 16529856fa1bSAl Viro { 16539856fa1bSAl Viro if (type == LAST_DOTDOT) { 16549856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 165570291aecSAl Viro return follow_dotdot_rcu(nd); 16569856fa1bSAl Viro } else 1657397d425dSEric W. Biederman return follow_dotdot(nd); 16589856fa1bSAl Viro } 16599856fa1bSAl Viro return 0; 16609856fa1bSAl Viro } 16619856fa1bSAl Viro 1662181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1663181548c0SAl Viro struct inode *inode, unsigned seq) 1664d63ff28fSAl Viro { 1665626de996SAl Viro int error; 16661cf2665bSAl Viro struct saved *last; 1667756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1668626de996SAl Viro path_to_nameidata(link, nd); 1669626de996SAl Viro return -ELOOP; 1670626de996SAl Viro } 1671bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1672cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1673cd179f44SAl Viro mntget(link->mnt); 16747973387aSAl Viro } 1675626de996SAl Viro error = nd_alloc_stack(nd); 1676626de996SAl Viro if (unlikely(error)) { 1677bc40aee0SAl Viro if (error == -ECHILD) { 1678bc40aee0SAl Viro if (unlikely(unlazy_link(nd, link, seq))) 1679bc40aee0SAl Viro return -ECHILD; 1680bc40aee0SAl Viro error = nd_alloc_stack(nd); 1681bc40aee0SAl Viro } 1682bc40aee0SAl Viro if (error) { 1683cd179f44SAl Viro path_put(link); 1684626de996SAl Viro return error; 1685626de996SAl Viro } 1686bc40aee0SAl Viro } 1687626de996SAl Viro 1688ab104923SAl Viro last = nd->stack + nd->depth++; 16891cf2665bSAl Viro last->link = *link; 1690ab104923SAl Viro last->cookie = NULL; 1691181548c0SAl Viro last->inode = inode; 16920450b2d1SAl Viro last->seq = seq; 1693d63ff28fSAl Viro return 1; 1694d63ff28fSAl Viro } 1695d63ff28fSAl Viro 16963ddcd056SLinus Torvalds /* 16973ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 16983ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 16993ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 17003ddcd056SLinus Torvalds * for the common case. 17013ddcd056SLinus Torvalds */ 1702254cf582SAl Viro static inline int should_follow_link(struct nameidata *nd, struct path *link, 1703181548c0SAl Viro int follow, 1704181548c0SAl Viro struct inode *inode, unsigned seq) 17053ddcd056SLinus Torvalds { 1706d63ff28fSAl Viro if (likely(!d_is_symlink(link->dentry))) 1707d63ff28fSAl Viro return 0; 1708d63ff28fSAl Viro if (!follow) 1709d63ff28fSAl Viro return 0; 1710181548c0SAl Viro return pick_link(nd, link, inode, seq); 17113ddcd056SLinus Torvalds } 17123ddcd056SLinus Torvalds 17134693a547SAl Viro enum {WALK_GET = 1, WALK_PUT = 2}; 17144693a547SAl Viro 17154693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1716ce57dfc1SAl Viro { 1717caa85634SAl Viro struct path path; 1718ce57dfc1SAl Viro struct inode *inode; 1719254cf582SAl Viro unsigned seq; 1720ce57dfc1SAl Viro int err; 1721ce57dfc1SAl Viro /* 1722ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1723ce57dfc1SAl Viro * to be able to know about the current root directory and 1724ce57dfc1SAl Viro * parent relationships. 1725ce57dfc1SAl Viro */ 17264693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 17274693a547SAl Viro err = handle_dots(nd, nd->last_type); 17284693a547SAl Viro if (flags & WALK_PUT) 17294693a547SAl Viro put_link(nd); 17304693a547SAl Viro return err; 17314693a547SAl Viro } 1732254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1733ce57dfc1SAl Viro if (unlikely(err)) { 1734697f514dSMiklos Szeredi if (err < 0) 1735f0a9ba70SAl Viro return err; 1736697f514dSMiklos Szeredi 1737caa85634SAl Viro err = lookup_slow(nd, &path); 1738697f514dSMiklos Szeredi if (err < 0) 1739f0a9ba70SAl Viro return err; 1740697f514dSMiklos Szeredi 174163afdfc7SDavid Howells inode = d_backing_inode(path.dentry); 1742254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1743697f514dSMiklos Szeredi err = -ENOENT; 1744caa85634SAl Viro if (d_is_negative(path.dentry)) 1745697f514dSMiklos Szeredi goto out_path_put; 1746766c4cbfSAl Viro } 1747697f514dSMiklos Szeredi 17484693a547SAl Viro if (flags & WALK_PUT) 17494693a547SAl Viro put_link(nd); 1750181548c0SAl Viro err = should_follow_link(nd, &path, flags & WALK_GET, inode, seq); 1751d63ff28fSAl Viro if (unlikely(err)) 1752d63ff28fSAl Viro return err; 1753caa85634SAl Viro path_to_nameidata(&path, nd); 1754ce57dfc1SAl Viro nd->inode = inode; 1755254cf582SAl Viro nd->seq = seq; 1756ce57dfc1SAl Viro return 0; 1757697f514dSMiklos Szeredi 1758697f514dSMiklos Szeredi out_path_put: 1759caa85634SAl Viro path_to_nameidata(&path, nd); 1760697f514dSMiklos Szeredi return err; 1761ce57dfc1SAl Viro } 1762ce57dfc1SAl Viro 17631da177e4SLinus Torvalds /* 1764bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1765bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1766bfcfaa77SLinus Torvalds * 1767bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1768bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1769bfcfaa77SLinus Torvalds * fast. 1770bfcfaa77SLinus Torvalds * 1771bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1772bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1773bfcfaa77SLinus Torvalds * crossing operation. 1774bfcfaa77SLinus Torvalds * 1775bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1776bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1777bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1778bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1779bfcfaa77SLinus Torvalds */ 1780bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1781bfcfaa77SLinus Torvalds 1782f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1783bfcfaa77SLinus Torvalds 1784f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1785bfcfaa77SLinus Torvalds 1786bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1787bfcfaa77SLinus Torvalds { 178899d263d4SLinus Torvalds return hash_64(hash, 32); 1789bfcfaa77SLinus Torvalds } 1790bfcfaa77SLinus Torvalds 1791bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1792bfcfaa77SLinus Torvalds 1793bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1794bfcfaa77SLinus Torvalds 1795bfcfaa77SLinus Torvalds #endif 1796bfcfaa77SLinus Torvalds 1797bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1798bfcfaa77SLinus Torvalds { 1799bfcfaa77SLinus Torvalds unsigned long a, mask; 1800bfcfaa77SLinus Torvalds unsigned long hash = 0; 1801bfcfaa77SLinus Torvalds 1802bfcfaa77SLinus Torvalds for (;;) { 1803e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1804bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1805bfcfaa77SLinus Torvalds break; 1806bfcfaa77SLinus Torvalds hash += a; 1807f132c5beSAl Viro hash *= 9; 1808bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1809bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1810bfcfaa77SLinus Torvalds if (!len) 1811bfcfaa77SLinus Torvalds goto done; 1812bfcfaa77SLinus Torvalds } 1813a5c21dceSWill Deacon mask = bytemask_from_count(len); 1814bfcfaa77SLinus Torvalds hash += mask & a; 1815bfcfaa77SLinus Torvalds done: 1816bfcfaa77SLinus Torvalds return fold_hash(hash); 1817bfcfaa77SLinus Torvalds } 1818bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1819bfcfaa77SLinus Torvalds 1820bfcfaa77SLinus Torvalds /* 1821bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1822d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1823bfcfaa77SLinus Torvalds */ 1824d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1825bfcfaa77SLinus Torvalds { 182636126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 182736126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1828bfcfaa77SLinus Torvalds 1829bfcfaa77SLinus Torvalds hash = a = 0; 1830bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1831bfcfaa77SLinus Torvalds do { 1832bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1833bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1834e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 183536126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 183636126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1837bfcfaa77SLinus Torvalds 183836126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 183936126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 184036126f8fSLinus Torvalds 184136126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 184236126f8fSLinus Torvalds 184336126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 18449226b5b4SLinus Torvalds len += find_zero(mask); 1845d6bb3e90SLinus Torvalds return hashlen_create(fold_hash(hash), len); 1846bfcfaa77SLinus Torvalds } 1847bfcfaa77SLinus Torvalds 1848bfcfaa77SLinus Torvalds #else 1849bfcfaa77SLinus Torvalds 18500145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 18510145acc2SLinus Torvalds { 18520145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 18530145acc2SLinus Torvalds while (len--) 18540145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 18550145acc2SLinus Torvalds return end_name_hash(hash); 18560145acc2SLinus Torvalds } 1857ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 18580145acc2SLinus Torvalds 18593ddcd056SLinus Torvalds /* 1860200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1861200e9ef7SLinus Torvalds * one character. 1862200e9ef7SLinus Torvalds */ 1863d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1864200e9ef7SLinus Torvalds { 1865200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1866200e9ef7SLinus Torvalds unsigned long len = 0, c; 1867200e9ef7SLinus Torvalds 1868200e9ef7SLinus Torvalds c = (unsigned char)*name; 1869200e9ef7SLinus Torvalds do { 1870200e9ef7SLinus Torvalds len++; 1871200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1872200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1873200e9ef7SLinus Torvalds } while (c && c != '/'); 1874d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 1875200e9ef7SLinus Torvalds } 1876200e9ef7SLinus Torvalds 1877bfcfaa77SLinus Torvalds #endif 1878bfcfaa77SLinus Torvalds 1879200e9ef7SLinus Torvalds /* 18801da177e4SLinus Torvalds * Name resolution. 1881ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1882ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 18831da177e4SLinus Torvalds * 1884ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1885ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 18861da177e4SLinus Torvalds */ 18876de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 18881da177e4SLinus Torvalds { 18891da177e4SLinus Torvalds int err; 18901da177e4SLinus Torvalds 18911da177e4SLinus Torvalds while (*name=='/') 18921da177e4SLinus Torvalds name++; 18931da177e4SLinus Torvalds if (!*name) 18949e18f10aSAl Viro return 0; 18951da177e4SLinus Torvalds 18961da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 18971da177e4SLinus Torvalds for(;;) { 1898d6bb3e90SLinus Torvalds u64 hash_len; 1899fe479a58SAl Viro int type; 19001da177e4SLinus Torvalds 190152094c8aSAl Viro err = may_lookup(nd); 19021da177e4SLinus Torvalds if (err) 19033595e234SAl Viro return err; 19041da177e4SLinus Torvalds 1905d6bb3e90SLinus Torvalds hash_len = hash_name(name); 19061da177e4SLinus Torvalds 1907fe479a58SAl Viro type = LAST_NORM; 1908d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 1909fe479a58SAl Viro case 2: 1910200e9ef7SLinus Torvalds if (name[1] == '.') { 1911fe479a58SAl Viro type = LAST_DOTDOT; 191216c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 191316c2cd71SAl Viro } 1914fe479a58SAl Viro break; 1915fe479a58SAl Viro case 1: 1916fe479a58SAl Viro type = LAST_DOT; 1917fe479a58SAl Viro } 19185a202bcdSAl Viro if (likely(type == LAST_NORM)) { 19195a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 192016c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 19215a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 1922a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 1923da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 19245a202bcdSAl Viro if (err < 0) 19253595e234SAl Viro return err; 1926d6bb3e90SLinus Torvalds hash_len = this.hash_len; 1927d6bb3e90SLinus Torvalds name = this.name; 19285a202bcdSAl Viro } 19295a202bcdSAl Viro } 1930fe479a58SAl Viro 1931d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 1932d6bb3e90SLinus Torvalds nd->last.name = name; 19335f4a6a69SAl Viro nd->last_type = type; 19345f4a6a69SAl Viro 1935d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 1936d6bb3e90SLinus Torvalds if (!*name) 1937bdf6cbf1SAl Viro goto OK; 1938200e9ef7SLinus Torvalds /* 1939200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1940200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1941200e9ef7SLinus Torvalds */ 1942200e9ef7SLinus Torvalds do { 1943d6bb3e90SLinus Torvalds name++; 1944d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 19458620c238SAl Viro if (unlikely(!*name)) { 19468620c238SAl Viro OK: 1947368ee9baSAl Viro /* pathname body, done */ 19488620c238SAl Viro if (!nd->depth) 19498620c238SAl Viro return 0; 19508620c238SAl Viro name = nd->stack[nd->depth - 1].name; 1951368ee9baSAl Viro /* trailing symlink, done */ 19528620c238SAl Viro if (!name) 19538620c238SAl Viro return 0; 19548620c238SAl Viro /* last component of nested symlink */ 19554693a547SAl Viro err = walk_component(nd, WALK_GET | WALK_PUT); 19568620c238SAl Viro } else { 19574693a547SAl Viro err = walk_component(nd, WALK_GET); 19588620c238SAl Viro } 1959ce57dfc1SAl Viro if (err < 0) 19603595e234SAl Viro return err; 1961fe479a58SAl Viro 1962ce57dfc1SAl Viro if (err) { 1963626de996SAl Viro const char *s = get_link(nd); 19645a460275SAl Viro 19653595e234SAl Viro if (unlikely(IS_ERR(s))) 19663595e234SAl Viro return PTR_ERR(s); 1967172a39a0SAl Viro err = 0; 196812b09578SAl Viro if (unlikely(!s)) { 196912b09578SAl Viro /* jumped */ 1970b9ff4429SAl Viro put_link(nd); 197112b09578SAl Viro } else { 1972071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 197332cd7468SAl Viro name = s; 19749e18f10aSAl Viro continue; 197548c8b0c5SAl Viro } 197631e6b01fSNick Piggin } 197797242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 197897242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 197997242f99SAl Viro if (unlazy_walk(nd, NULL, 0)) 198097242f99SAl Viro return -ECHILD; 198197242f99SAl Viro } 19823595e234SAl Viro return -ENOTDIR; 19835f4a6a69SAl Viro } 1984ce57dfc1SAl Viro } 198597242f99SAl Viro } 19861da177e4SLinus Torvalds 1987c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 198831e6b01fSNick Piggin { 198931e6b01fSNick Piggin int retval = 0; 1990c8a53ee5SAl Viro const char *s = nd->name->name; 199131e6b01fSNick Piggin 199231e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 1993980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 199431e6b01fSNick Piggin nd->depth = 0; 1995368ee9baSAl Viro nd->total_link_count = 0; 19965b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 1997b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 1998b18825a7SDavid Howells struct inode *inode = root->d_inode; 1999fd2f7cb5SAl Viro if (*s) { 200044b1d530SMiklos Szeredi if (!d_can_lookup(root)) 2001368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 20025b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 20035b6ca027SAl Viro if (retval) 2004368ee9baSAl Viro return ERR_PTR(retval); 200573d049a4SAl Viro } 20065b6ca027SAl Viro nd->path = nd->root; 20075b6ca027SAl Viro nd->inode = inode; 20085b6ca027SAl Viro if (flags & LOOKUP_RCU) { 20098b61e74fSAl Viro rcu_read_lock(); 20105b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 20118f47a016SAl Viro nd->root_seq = nd->seq; 201248a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 20135b6ca027SAl Viro } else { 20145b6ca027SAl Viro path_get(&nd->path); 20155b6ca027SAl Viro } 2016368ee9baSAl Viro return s; 20175b6ca027SAl Viro } 20185b6ca027SAl Viro 201931e6b01fSNick Piggin nd->root.mnt = NULL; 202031e6b01fSNick Piggin 202148a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 2022fd2f7cb5SAl Viro if (*s == '/') { 2023e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 20248b61e74fSAl Viro rcu_read_lock(); 202506d7137eSAl Viro set_root_rcu(nd); 202606d7137eSAl Viro nd->seq = nd->root_seq; 2027e41f7d4eSAl Viro } else { 2028e41f7d4eSAl Viro set_root(nd); 2029e41f7d4eSAl Viro path_get(&nd->root); 2030e41f7d4eSAl Viro } 203131e6b01fSNick Piggin nd->path = nd->root; 2032c8a53ee5SAl Viro } else if (nd->dfd == AT_FDCWD) { 2033e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 203431e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2035c28cc364SNick Piggin unsigned seq; 203631e6b01fSNick Piggin 20378b61e74fSAl Viro rcu_read_lock(); 203831e6b01fSNick Piggin 2039c28cc364SNick Piggin do { 2040c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 204131e6b01fSNick Piggin nd->path = fs->pwd; 2042c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2043c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2044e41f7d4eSAl Viro } else { 2045e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2046e41f7d4eSAl Viro } 204731e6b01fSNick Piggin } else { 2048582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2049c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 205031e6b01fSNick Piggin struct dentry *dentry; 205131e6b01fSNick Piggin 20522903ff01SAl Viro if (!f.file) 2053368ee9baSAl Viro return ERR_PTR(-EBADF); 205431e6b01fSNick Piggin 20552903ff01SAl Viro dentry = f.file->f_path.dentry; 205631e6b01fSNick Piggin 2057fd2f7cb5SAl Viro if (*s) { 205844b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 20592903ff01SAl Viro fdput(f); 2060368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2061f52e0c11SAl Viro } 20622903ff01SAl Viro } 20632903ff01SAl Viro 20642903ff01SAl Viro nd->path = f.file->f_path; 2065e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 20668b61e74fSAl Viro rcu_read_lock(); 206734a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 206834a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 20695590ff0dSUlrich Drepper } else { 20702903ff01SAl Viro path_get(&nd->path); 207134a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 20721da177e4SLinus Torvalds } 207334a26b99SAl Viro fdput(f); 2074368ee9baSAl Viro return s; 2075e41f7d4eSAl Viro } 2076e41f7d4eSAl Viro 207731e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 20784023bfc9SAl Viro if (!(flags & LOOKUP_RCU)) 2079368ee9baSAl Viro return s; 20804023bfc9SAl Viro if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) 2081368ee9baSAl Viro return s; 20824023bfc9SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 20834023bfc9SAl Viro nd->root.mnt = NULL; 20844023bfc9SAl Viro rcu_read_unlock(); 2085368ee9baSAl Viro return ERR_PTR(-ECHILD); 20869b4a9b14SAl Viro } 20879b4a9b14SAl Viro 20883bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 208995fa25d9SAl Viro { 209095fa25d9SAl Viro const char *s; 2091fec2fa24SAl Viro int error = may_follow_link(nd); 2092deb106c6SAl Viro if (unlikely(error)) 20933bdba28bSAl Viro return ERR_PTR(error); 209495fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2095fab51e8aSAl Viro nd->stack[0].name = NULL; 20963b2e7f75SAl Viro s = get_link(nd); 2097deb106c6SAl Viro return s ? s : ""; 209895fa25d9SAl Viro } 209995fa25d9SAl Viro 2100caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2101bd92d7feSAl Viro { 2102bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2103bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2104bd92d7feSAl Viro 2105bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 2106deb106c6SAl Viro return walk_component(nd, 21074693a547SAl Viro nd->flags & LOOKUP_FOLLOW 21084693a547SAl Viro ? nd->depth 21094693a547SAl Viro ? WALK_PUT | WALK_GET 21104693a547SAl Viro : WALK_GET 21114693a547SAl Viro : 0); 2112bd92d7feSAl Viro } 2113bd92d7feSAl Viro 21149b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2115c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 21169b4a9b14SAl Viro { 2117c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2118bd92d7feSAl Viro int err; 211931e6b01fSNick Piggin 2120368ee9baSAl Viro if (IS_ERR(s)) 2121368ee9baSAl Viro return PTR_ERR(s); 21223bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 21233bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 21243bdba28bSAl Viro s = trailing_symlink(nd); 21253bdba28bSAl Viro if (IS_ERR(s)) { 21263bdba28bSAl Viro err = PTR_ERR(s); 21276d7b5aaeSAl Viro break; 2128bd92d7feSAl Viro } 2129bd92d7feSAl Viro } 21309f1fafeeSAl Viro if (!err) 21319f1fafeeSAl Viro err = complete_walk(nd); 2132bd92d7feSAl Viro 2133deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2134deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2135bd23a539SAl Viro err = -ENOTDIR; 2136625b6d10SAl Viro if (!err) { 2137625b6d10SAl Viro *path = nd->path; 2138625b6d10SAl Viro nd->path.mnt = NULL; 2139625b6d10SAl Viro nd->path.dentry = NULL; 2140625b6d10SAl Viro } 2141deb106c6SAl Viro terminate_walk(nd); 2142bd92d7feSAl Viro return err; 214331e6b01fSNick Piggin } 214431e6b01fSNick Piggin 2145625b6d10SAl Viro static int filename_lookup(int dfd, struct filename *name, unsigned flags, 21469ad1aaa6SAl Viro struct path *path, struct path *root) 2147873f1eedSJeff Layton { 2148894bc8c4SAl Viro int retval; 21499883d185SAl Viro struct nameidata nd; 2150abc9f5beSAl Viro if (IS_ERR(name)) 2151abc9f5beSAl Viro return PTR_ERR(name); 21529ad1aaa6SAl Viro if (unlikely(root)) { 21539ad1aaa6SAl Viro nd.root = *root; 21549ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 21559ad1aaa6SAl Viro } 21569883d185SAl Viro set_nameidata(&nd, dfd, name); 2157c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2158873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2159c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2160873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2161c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2162873f1eedSJeff Layton 2163873f1eedSJeff Layton if (likely(!retval)) 2164625b6d10SAl Viro audit_inode(name, path->dentry, flags & LOOKUP_PARENT); 21659883d185SAl Viro restore_nameidata(); 2166e4bd1c1aSAl Viro putname(name); 2167873f1eedSJeff Layton return retval; 2168873f1eedSJeff Layton } 2169873f1eedSJeff Layton 21708bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2171c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2172391172c4SAl Viro struct path *parent) 21738bcb77faSAl Viro { 2174c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2175368ee9baSAl Viro int err; 2176368ee9baSAl Viro if (IS_ERR(s)) 2177368ee9baSAl Viro return PTR_ERR(s); 2178368ee9baSAl Viro err = link_path_walk(s, nd); 21798bcb77faSAl Viro if (!err) 21808bcb77faSAl Viro err = complete_walk(nd); 2181391172c4SAl Viro if (!err) { 2182391172c4SAl Viro *parent = nd->path; 2183391172c4SAl Viro nd->path.mnt = NULL; 2184391172c4SAl Viro nd->path.dentry = NULL; 2185391172c4SAl Viro } 2186deb106c6SAl Viro terminate_walk(nd); 21878bcb77faSAl Viro return err; 21888bcb77faSAl Viro } 21898bcb77faSAl Viro 21905c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2191391172c4SAl Viro unsigned int flags, struct path *parent, 2192391172c4SAl Viro struct qstr *last, int *type) 21938bcb77faSAl Viro { 21948bcb77faSAl Viro int retval; 21959883d185SAl Viro struct nameidata nd; 21968bcb77faSAl Viro 21975c31b6ceSAl Viro if (IS_ERR(name)) 21985c31b6ceSAl Viro return name; 21999883d185SAl Viro set_nameidata(&nd, dfd, name); 2200c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 22018bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2202c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 22038bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2204c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2205391172c4SAl Viro if (likely(!retval)) { 2206391172c4SAl Viro *last = nd.last; 2207391172c4SAl Viro *type = nd.last_type; 2208391172c4SAl Viro audit_inode(name, parent->dentry, LOOKUP_PARENT); 22095c31b6ceSAl Viro } else { 22105c31b6ceSAl Viro putname(name); 22115c31b6ceSAl Viro name = ERR_PTR(retval); 2212391172c4SAl Viro } 22139883d185SAl Viro restore_nameidata(); 22145c31b6ceSAl Viro return name; 22158bcb77faSAl Viro } 22168bcb77faSAl Viro 221779714f72SAl Viro /* does lookup, returns the object with parent locked */ 221879714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 22195590ff0dSUlrich Drepper { 22205c31b6ceSAl Viro struct filename *filename; 22215c31b6ceSAl Viro struct dentry *d; 2222391172c4SAl Viro struct qstr last; 2223391172c4SAl Viro int type; 222451689104SPaul Moore 22255c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 22265c31b6ceSAl Viro &last, &type); 222751689104SPaul Moore if (IS_ERR(filename)) 222851689104SPaul Moore return ERR_CAST(filename); 22295c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2230391172c4SAl Viro path_put(path); 22315c31b6ceSAl Viro putname(filename); 22325c31b6ceSAl Viro return ERR_PTR(-EINVAL); 223379714f72SAl Viro } 2234391172c4SAl Viro mutex_lock_nested(&path->dentry->d_inode->i_mutex, I_MUTEX_PARENT); 2235391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 223679714f72SAl Viro if (IS_ERR(d)) { 2237391172c4SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 2238391172c4SAl Viro path_put(path); 223979714f72SAl Viro } 224051689104SPaul Moore putname(filename); 224179714f72SAl Viro return d; 22425590ff0dSUlrich Drepper } 22435590ff0dSUlrich Drepper 2244d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2245d1811465SAl Viro { 2246abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2247abc9f5beSAl Viro flags, path, NULL); 2248d1811465SAl Viro } 22494d359507SAl Viro EXPORT_SYMBOL(kern_path); 2250d1811465SAl Viro 225116f18200SJosef 'Jeff' Sipek /** 225216f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 225316f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 225416f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 225516f18200SJosef 'Jeff' Sipek * @name: pointer to file name 225616f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2257e0a01249SAl Viro * @path: pointer to struct path to fill 225816f18200SJosef 'Jeff' Sipek */ 225916f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 226016f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2261e0a01249SAl Viro struct path *path) 226216f18200SJosef 'Jeff' Sipek { 22639ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 22649ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2265abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2266abc9f5beSAl Viro flags , path, &root); 226716f18200SJosef 'Jeff' Sipek } 22684d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 226916f18200SJosef 'Jeff' Sipek 2270eead1911SChristoph Hellwig /** 2271a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2272eead1911SChristoph Hellwig * @name: pathname component to lookup 2273eead1911SChristoph Hellwig * @base: base directory to lookup from 2274eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2275eead1911SChristoph Hellwig * 2276a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 22779e7543e9SAl Viro * not be called by generic code. 2278eead1911SChristoph Hellwig */ 2279057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2280057f6c01SJames Morris { 2281057f6c01SJames Morris struct qstr this; 22826a96ba54SAl Viro unsigned int c; 2283cda309deSMiklos Szeredi int err; 2284057f6c01SJames Morris 22852f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 22862f9092e1SDavid Woodhouse 22876a96ba54SAl Viro this.name = name; 22886a96ba54SAl Viro this.len = len; 22890145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 22906a96ba54SAl Viro if (!len) 22916a96ba54SAl Viro return ERR_PTR(-EACCES); 22926a96ba54SAl Viro 229321d8a15aSAl Viro if (unlikely(name[0] == '.')) { 229421d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 229521d8a15aSAl Viro return ERR_PTR(-EACCES); 229621d8a15aSAl Viro } 229721d8a15aSAl Viro 22986a96ba54SAl Viro while (len--) { 22996a96ba54SAl Viro c = *(const unsigned char *)name++; 23006a96ba54SAl Viro if (c == '/' || c == '\0') 23016a96ba54SAl Viro return ERR_PTR(-EACCES); 23026a96ba54SAl Viro } 23035a202bcdSAl Viro /* 23045a202bcdSAl Viro * See if the low-level filesystem might want 23055a202bcdSAl Viro * to use its own hash.. 23065a202bcdSAl Viro */ 23075a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2308da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 23095a202bcdSAl Viro if (err < 0) 23105a202bcdSAl Viro return ERR_PTR(err); 23115a202bcdSAl Viro } 2312eead1911SChristoph Hellwig 2313cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2314cda309deSMiklos Szeredi if (err) 2315cda309deSMiklos Szeredi return ERR_PTR(err); 2316cda309deSMiklos Szeredi 231772bd866aSAl Viro return __lookup_hash(&this, base, 0); 2318057f6c01SJames Morris } 23194d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2320057f6c01SJames Morris 23211fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 23221fa1e7f6SAndy Whitcroft struct path *path, int *empty) 23231da177e4SLinus Torvalds { 2324abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2325abc9f5beSAl Viro flags, path, NULL); 23261da177e4SLinus Torvalds } 2327b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 23281fa1e7f6SAndy Whitcroft 2329873f1eedSJeff Layton /* 2330873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2331873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2332873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2333873f1eedSJeff Layton * path-walking is complete. 2334873f1eedSJeff Layton */ 2335a2ec4a2dSAl Viro static inline struct filename * 2336f5beed75SAl Viro user_path_parent(int dfd, const char __user *path, 2337f5beed75SAl Viro struct path *parent, 2338f5beed75SAl Viro struct qstr *last, 2339f5beed75SAl Viro int *type, 23409e790bd6SJeff Layton unsigned int flags) 23412ad94ae6SAl Viro { 23429e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 23435c31b6ceSAl Viro return filename_parentat(dfd, getname(path), flags & LOOKUP_REVAL, 23445c31b6ceSAl Viro parent, last, type); 23452ad94ae6SAl Viro } 23462ad94ae6SAl Viro 23478033426eSJeff Layton /** 2348197df04cSAl Viro * mountpoint_last - look up last component for umount 23498033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 23508033426eSJeff Layton * @path: pointer to container for result 23518033426eSJeff Layton * 23528033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 23538033426eSJeff Layton * need to resolve the path without doing any revalidation. 23548033426eSJeff Layton * 23558033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 23568033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 23578033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 23588033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 23598033426eSJeff Layton * bogus and it doesn't exist. 23608033426eSJeff Layton * 23618033426eSJeff Layton * Returns: 23628033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 23638033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 23648033426eSJeff Layton * put in this case. 23658033426eSJeff Layton * 23668033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 23678033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 23688033426eSJeff Layton * The nd->path reference will also be put. 23698033426eSJeff Layton * 23708033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 23718033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 23728033426eSJeff Layton * to the link, and nd->path will *not* be put. 23738033426eSJeff Layton */ 23748033426eSJeff Layton static int 2375197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 23768033426eSJeff Layton { 23778033426eSJeff Layton int error = 0; 23788033426eSJeff Layton struct dentry *dentry; 23798033426eSJeff Layton struct dentry *dir = nd->path.dentry; 23808033426eSJeff Layton 238135759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 238235759521SAl Viro if (nd->flags & LOOKUP_RCU) { 23836e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 2384deb106c6SAl Viro return -ECHILD; 23858033426eSJeff Layton } 23868033426eSJeff Layton 23878033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 23888033426eSJeff Layton 23898033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 23908033426eSJeff Layton error = handle_dots(nd, nd->last_type); 239135759521SAl Viro if (error) 2392deb106c6SAl Viro return error; 23938033426eSJeff Layton dentry = dget(nd->path.dentry); 239435759521SAl Viro goto done; 23958033426eSJeff Layton } 23968033426eSJeff Layton 23978033426eSJeff Layton mutex_lock(&dir->d_inode->i_mutex); 23988033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 23998033426eSJeff Layton if (!dentry) { 24008033426eSJeff Layton /* 24018033426eSJeff Layton * No cached dentry. Mounted dentries are pinned in the cache, 24028033426eSJeff Layton * so that means that this dentry is probably a symlink or the 24038033426eSJeff Layton * path doesn't actually point to a mounted dentry. 24048033426eSJeff Layton */ 24058033426eSJeff Layton dentry = d_alloc(dir, &nd->last); 24068033426eSJeff Layton if (!dentry) { 2407bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 2408deb106c6SAl Viro return -ENOMEM; 24098033426eSJeff Layton } 241035759521SAl Viro dentry = lookup_real(dir->d_inode, dentry, nd->flags); 2411bcceeebaSDave Jones if (IS_ERR(dentry)) { 2412bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 2413deb106c6SAl Viro return PTR_ERR(dentry); 24148033426eSJeff Layton } 2415bcceeebaSDave Jones } 24168033426eSJeff Layton mutex_unlock(&dir->d_inode->i_mutex); 24178033426eSJeff Layton 241835759521SAl Viro done: 2419698934dfSDavid Howells if (d_is_negative(dentry)) { 24208033426eSJeff Layton dput(dentry); 2421deb106c6SAl Viro return -ENOENT; 242235759521SAl Viro } 2423191d7f73SAl Viro if (nd->depth) 2424191d7f73SAl Viro put_link(nd); 24258033426eSJeff Layton path->dentry = dentry; 2426295dc39dSVasily Averin path->mnt = nd->path.mnt; 2427181548c0SAl Viro error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW, 2428181548c0SAl Viro d_backing_inode(dentry), 0); 2429deb106c6SAl Viro if (unlikely(error)) 2430d63ff28fSAl Viro return error; 2431295dc39dSVasily Averin mntget(path->mnt); 24328033426eSJeff Layton follow_mount(path); 2433deb106c6SAl Viro return 0; 24348033426eSJeff Layton } 24358033426eSJeff Layton 24368033426eSJeff Layton /** 2437197df04cSAl Viro * path_mountpoint - look up a path to be umounted 24382a78b857SMasanari Iida * @nd: lookup context 24398033426eSJeff Layton * @flags: lookup flags 2440c8a53ee5SAl Viro * @path: pointer to container for result 24418033426eSJeff Layton * 24428033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2443606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 24448033426eSJeff Layton */ 24458033426eSJeff Layton static int 2446c8a53ee5SAl Viro path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) 24478033426eSJeff Layton { 2448c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2449368ee9baSAl Viro int err; 2450368ee9baSAl Viro if (IS_ERR(s)) 2451368ee9baSAl Viro return PTR_ERR(s); 24523bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 24533bdba28bSAl Viro (err = mountpoint_last(nd, path)) > 0) { 24543bdba28bSAl Viro s = trailing_symlink(nd); 24553bdba28bSAl Viro if (IS_ERR(s)) { 24563bdba28bSAl Viro err = PTR_ERR(s); 24578033426eSJeff Layton break; 24588033426eSJeff Layton } 24593bdba28bSAl Viro } 2460deb106c6SAl Viro terminate_walk(nd); 24618033426eSJeff Layton return err; 24628033426eSJeff Layton } 24638033426eSJeff Layton 24642d864651SAl Viro static int 2465668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 24662d864651SAl Viro unsigned int flags) 24672d864651SAl Viro { 24689883d185SAl Viro struct nameidata nd; 2469cbaab2dbSAl Viro int error; 2470668696dcSAl Viro if (IS_ERR(name)) 2471668696dcSAl Viro return PTR_ERR(name); 24729883d185SAl Viro set_nameidata(&nd, dfd, name); 2473c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); 24742d864651SAl Viro if (unlikely(error == -ECHILD)) 2475c8a53ee5SAl Viro error = path_mountpoint(&nd, flags, path); 24762d864651SAl Viro if (unlikely(error == -ESTALE)) 2477c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); 24782d864651SAl Viro if (likely(!error)) 2479668696dcSAl Viro audit_inode(name, path->dentry, 0); 24809883d185SAl Viro restore_nameidata(); 2481668696dcSAl Viro putname(name); 24822d864651SAl Viro return error; 24832d864651SAl Viro } 24842d864651SAl Viro 24858033426eSJeff Layton /** 2486197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 24878033426eSJeff Layton * @dfd: directory file descriptor 24888033426eSJeff Layton * @name: pathname from userland 24898033426eSJeff Layton * @flags: lookup flags 24908033426eSJeff Layton * @path: pointer to container to hold result 24918033426eSJeff Layton * 24928033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 24938033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 24948033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 24958033426eSJeff Layton * and avoid revalidating the last component. 24968033426eSJeff Layton * 24978033426eSJeff Layton * Returns 0 and populates "path" on success. 24988033426eSJeff Layton */ 24998033426eSJeff Layton int 2500197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 25018033426eSJeff Layton struct path *path) 25028033426eSJeff Layton { 2503cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 25048033426eSJeff Layton } 25058033426eSJeff Layton 25062d864651SAl Viro int 25072d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 25082d864651SAl Viro unsigned int flags) 25092d864651SAl Viro { 2510cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 25112d864651SAl Viro } 25122d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 25132d864651SAl Viro 2514cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 25151da177e4SLinus Torvalds { 25168e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2517da9592edSDavid Howells 25188e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 25191da177e4SLinus Torvalds return 0; 25208e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 25211da177e4SLinus Torvalds return 0; 252223adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 25231da177e4SLinus Torvalds } 2524cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 25251da177e4SLinus Torvalds 25261da177e4SLinus Torvalds /* 25271da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 25281da177e4SLinus Torvalds * whether the type of victim is right. 25291da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 25301da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 25311da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 25321da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 25331da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 25341da177e4SLinus Torvalds * a. be owner of dir, or 25351da177e4SLinus Torvalds * b. be owner of victim, or 25361da177e4SLinus Torvalds * c. have CAP_FOWNER capability 25371da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 25381da177e4SLinus Torvalds * links pointing to it. 25391da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 25401da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 25411da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 25421da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 25431da177e4SLinus Torvalds * nfs_async_unlink(). 25441da177e4SLinus Torvalds */ 2545b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 25461da177e4SLinus Torvalds { 254763afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 25481da177e4SLinus Torvalds int error; 25491da177e4SLinus Torvalds 2550b18825a7SDavid Howells if (d_is_negative(victim)) 25511da177e4SLinus Torvalds return -ENOENT; 2552b18825a7SDavid Howells BUG_ON(!inode); 25531da177e4SLinus Torvalds 25541da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 25554fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 25561da177e4SLinus Torvalds 2557f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 25581da177e4SLinus Torvalds if (error) 25591da177e4SLinus Torvalds return error; 25601da177e4SLinus Torvalds if (IS_APPEND(dir)) 25611da177e4SLinus Torvalds return -EPERM; 2562b18825a7SDavid Howells 2563b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2564b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 25651da177e4SLinus Torvalds return -EPERM; 25661da177e4SLinus Torvalds if (isdir) { 256744b1d530SMiklos Szeredi if (!d_is_dir(victim)) 25681da177e4SLinus Torvalds return -ENOTDIR; 25691da177e4SLinus Torvalds if (IS_ROOT(victim)) 25701da177e4SLinus Torvalds return -EBUSY; 257144b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 25721da177e4SLinus Torvalds return -EISDIR; 25731da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25741da177e4SLinus Torvalds return -ENOENT; 25751da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 25761da177e4SLinus Torvalds return -EBUSY; 25771da177e4SLinus Torvalds return 0; 25781da177e4SLinus Torvalds } 25791da177e4SLinus Torvalds 25801da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 25811da177e4SLinus Torvalds * dir. 25821da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 25831da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 25841da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 25851da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 25861da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 25871da177e4SLinus Torvalds */ 2588a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 25891da177e4SLinus Torvalds { 259014e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 25911da177e4SLinus Torvalds if (child->d_inode) 25921da177e4SLinus Torvalds return -EEXIST; 25931da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25941da177e4SLinus Torvalds return -ENOENT; 2595f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 25961da177e4SLinus Torvalds } 25971da177e4SLinus Torvalds 25981da177e4SLinus Torvalds /* 25991da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 26001da177e4SLinus Torvalds */ 26011da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 26021da177e4SLinus Torvalds { 26031da177e4SLinus Torvalds struct dentry *p; 26041da177e4SLinus Torvalds 26051da177e4SLinus Torvalds if (p1 == p2) { 2606f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 26071da177e4SLinus Torvalds return NULL; 26081da177e4SLinus Torvalds } 26091da177e4SLinus Torvalds 2610a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 26111da177e4SLinus Torvalds 2612e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2613e2761a11SOGAWA Hirofumi if (p) { 2614f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2615f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 26161da177e4SLinus Torvalds return p; 26171da177e4SLinus Torvalds } 26181da177e4SLinus Torvalds 2619e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2620e2761a11SOGAWA Hirofumi if (p) { 2621f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2622f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 26231da177e4SLinus Torvalds return p; 26241da177e4SLinus Torvalds } 26251da177e4SLinus Torvalds 2626f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2627d1b72cc6SMiklos Szeredi mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); 26281da177e4SLinus Torvalds return NULL; 26291da177e4SLinus Torvalds } 26304d359507SAl Viro EXPORT_SYMBOL(lock_rename); 26311da177e4SLinus Torvalds 26321da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 26331da177e4SLinus Torvalds { 26341b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 26351da177e4SLinus Torvalds if (p1 != p2) { 26361b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2637a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 26381da177e4SLinus Torvalds } 26391da177e4SLinus Torvalds } 26404d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 26411da177e4SLinus Torvalds 26424acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2643312b63fbSAl Viro bool want_excl) 26441da177e4SLinus Torvalds { 2645a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 26461da177e4SLinus Torvalds if (error) 26471da177e4SLinus Torvalds return error; 26481da177e4SLinus Torvalds 2649acfa4380SAl Viro if (!dir->i_op->create) 26501da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 26511da177e4SLinus Torvalds mode &= S_IALLUGO; 26521da177e4SLinus Torvalds mode |= S_IFREG; 26531da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 26541da177e4SLinus Torvalds if (error) 26551da177e4SLinus Torvalds return error; 2656312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2657a74574aaSStephen Smalley if (!error) 2658f38aa942SAmy Griffis fsnotify_create(dir, dentry); 26591da177e4SLinus Torvalds return error; 26601da177e4SLinus Torvalds } 26614d359507SAl Viro EXPORT_SYMBOL(vfs_create); 26621da177e4SLinus Torvalds 266373d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 26641da177e4SLinus Torvalds { 26653fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 26661da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 26671da177e4SLinus Torvalds int error; 26681da177e4SLinus Torvalds 2669bcda7652SAl Viro /* O_PATH? */ 2670bcda7652SAl Viro if (!acc_mode) 2671bcda7652SAl Viro return 0; 2672bcda7652SAl Viro 26731da177e4SLinus Torvalds if (!inode) 26741da177e4SLinus Torvalds return -ENOENT; 26751da177e4SLinus Torvalds 2676c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2677c8fe8f30SChristoph Hellwig case S_IFLNK: 26781da177e4SLinus Torvalds return -ELOOP; 2679c8fe8f30SChristoph Hellwig case S_IFDIR: 2680c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 26811da177e4SLinus Torvalds return -EISDIR; 2682c8fe8f30SChristoph Hellwig break; 2683c8fe8f30SChristoph Hellwig case S_IFBLK: 2684c8fe8f30SChristoph Hellwig case S_IFCHR: 26853fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 26861da177e4SLinus Torvalds return -EACCES; 2687c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2688c8fe8f30SChristoph Hellwig case S_IFIFO: 2689c8fe8f30SChristoph Hellwig case S_IFSOCK: 26901da177e4SLinus Torvalds flag &= ~O_TRUNC; 2691c8fe8f30SChristoph Hellwig break; 26924a3fd211SDave Hansen } 2693b41572e9SDave Hansen 26943fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2695b41572e9SDave Hansen if (error) 2696b41572e9SDave Hansen return error; 26976146f0d5SMimi Zohar 26981da177e4SLinus Torvalds /* 26991da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 27001da177e4SLinus Torvalds */ 27011da177e4SLinus Torvalds if (IS_APPEND(inode)) { 27028737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 27037715b521SAl Viro return -EPERM; 27041da177e4SLinus Torvalds if (flag & O_TRUNC) 27057715b521SAl Viro return -EPERM; 27061da177e4SLinus Torvalds } 27071da177e4SLinus Torvalds 27081da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 27092e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 27107715b521SAl Viro return -EPERM; 27111da177e4SLinus Torvalds 2712f3c7691eSJ. Bruce Fields return 0; 27137715b521SAl Viro } 27147715b521SAl Viro 2715e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 27167715b521SAl Viro { 2717e1181ee6SJeff Layton struct path *path = &filp->f_path; 27187715b521SAl Viro struct inode *inode = path->dentry->d_inode; 27197715b521SAl Viro int error = get_write_access(inode); 27201da177e4SLinus Torvalds if (error) 27217715b521SAl Viro return error; 27221da177e4SLinus Torvalds /* 27231da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 27241da177e4SLinus Torvalds */ 2725d7a06983SJeff Layton error = locks_verify_locked(filp); 2726be6d3e56SKentaro Takeda if (!error) 2727ea0d3ab2STetsuo Handa error = security_path_truncate(path); 27281da177e4SLinus Torvalds if (!error) { 27297715b521SAl Viro error = do_truncate(path->dentry, 0, 2730d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2731e1181ee6SJeff Layton filp); 27321da177e4SLinus Torvalds } 27331da177e4SLinus Torvalds put_write_access(inode); 2734acd0c935SMimi Zohar return error; 27351da177e4SLinus Torvalds } 27361da177e4SLinus Torvalds 2737d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2738d57999e1SDave Hansen { 27398a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 27408a5e929dSAl Viro flag--; 2741d57999e1SDave Hansen return flag; 2742d57999e1SDave Hansen } 2743d57999e1SDave Hansen 2744d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2745d18e9008SMiklos Szeredi { 2746d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2747d18e9008SMiklos Szeredi if (error) 2748d18e9008SMiklos Szeredi return error; 2749d18e9008SMiklos Szeredi 2750d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2751d18e9008SMiklos Szeredi if (error) 2752d18e9008SMiklos Szeredi return error; 2753d18e9008SMiklos Szeredi 2754d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2755d18e9008SMiklos Szeredi } 2756d18e9008SMiklos Szeredi 27571acf0af9SDavid Howells /* 27581acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 27591acf0af9SDavid Howells * dentry. 27601acf0af9SDavid Howells * 27611acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 27621acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 27631acf0af9SDavid Howells * 27641acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 27651acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 27661acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 27671acf0af9SDavid Howells * 27681acf0af9SDavid Howells * Returns an error code otherwise. 27691acf0af9SDavid Howells */ 27702675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 277130d90494SAl Viro struct path *path, struct file *file, 2772015c3bbcSMiklos Szeredi const struct open_flags *op, 277364894cf8SAl Viro bool got_write, bool need_lookup, 277447237687SAl Viro int *opened) 2775d18e9008SMiklos Szeredi { 2776d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2777d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2778d18e9008SMiklos Szeredi umode_t mode; 2779d18e9008SMiklos Szeredi int error; 2780d18e9008SMiklos Szeredi int acc_mode; 2781d18e9008SMiklos Szeredi int create_error = 0; 2782d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2783116cc022SMiklos Szeredi bool excl; 2784d18e9008SMiklos Szeredi 2785d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2786d18e9008SMiklos Szeredi 2787d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2788d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 27892675a4ebSAl Viro error = -ENOENT; 2790d18e9008SMiklos Szeredi goto out; 2791d18e9008SMiklos Szeredi } 2792d18e9008SMiklos Szeredi 279362b259d8SMiklos Szeredi mode = op->mode; 2794d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2795d18e9008SMiklos Szeredi mode &= ~current_umask(); 2796d18e9008SMiklos Szeredi 2797116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2798116cc022SMiklos Szeredi if (excl) 2799d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2800d18e9008SMiklos Szeredi 2801d18e9008SMiklos Szeredi /* 2802d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2803d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2804d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2805d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2806d18e9008SMiklos Szeredi * 2807d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2808d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2809d18e9008SMiklos Szeredi */ 281064894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 281164894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 281264894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2813d18e9008SMiklos Szeredi /* 2814d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2815d18e9008SMiklos Szeredi * back to lookup + open 2816d18e9008SMiklos Szeredi */ 2817d18e9008SMiklos Szeredi goto no_open; 2818d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2819d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 282064894cf8SAl Viro create_error = -EROFS; 2821d18e9008SMiklos Szeredi goto no_open; 2822d18e9008SMiklos Szeredi } else { 2823d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 282464894cf8SAl Viro create_error = -EROFS; 2825d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2826d18e9008SMiklos Szeredi } 2827d18e9008SMiklos Szeredi } 2828d18e9008SMiklos Szeredi 2829d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 283038227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2831d18e9008SMiklos Szeredi if (error) { 2832d18e9008SMiklos Szeredi create_error = error; 2833d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2834d18e9008SMiklos Szeredi goto no_open; 2835d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2836d18e9008SMiklos Szeredi } 2837d18e9008SMiklos Szeredi } 2838d18e9008SMiklos Szeredi 2839d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2840d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2841d18e9008SMiklos Szeredi 284230d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 284330d90494SAl Viro file->f_path.mnt = nd->path.mnt; 284430d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 284547237687SAl Viro opened); 2846d9585277SAl Viro if (error < 0) { 2847d9585277SAl Viro if (create_error && error == -ENOENT) 2848d9585277SAl Viro error = create_error; 2849d18e9008SMiklos Szeredi goto out; 2850d18e9008SMiklos Szeredi } 2851d18e9008SMiklos Szeredi 2852d9585277SAl Viro if (error) { /* returned 1, that is */ 285330d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 28542675a4ebSAl Viro error = -EIO; 2855d18e9008SMiklos Szeredi goto out; 2856d18e9008SMiklos Szeredi } 285730d90494SAl Viro if (file->f_path.dentry) { 2858d18e9008SMiklos Szeredi dput(dentry); 285930d90494SAl Viro dentry = file->f_path.dentry; 2860d18e9008SMiklos Szeredi } 286103da633aSAl Viro if (*opened & FILE_CREATED) 286203da633aSAl Viro fsnotify_create(dir, dentry); 286303da633aSAl Viro if (!dentry->d_inode) { 286403da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 286503da633aSAl Viro if (create_error) { 286662b2ce96SSage Weil error = create_error; 286762b2ce96SSage Weil goto out; 286862b2ce96SSage Weil } 286903da633aSAl Viro } else { 287003da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 287103da633aSAl Viro error = -EEXIST; 287203da633aSAl Viro goto out; 287303da633aSAl Viro } 287403da633aSAl Viro } 2875d18e9008SMiklos Szeredi goto looked_up; 2876d18e9008SMiklos Szeredi } 2877d18e9008SMiklos Szeredi 2878d18e9008SMiklos Szeredi /* 2879d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2880d18e9008SMiklos Szeredi * here. 2881d18e9008SMiklos Szeredi */ 288203da633aSAl Viro acc_mode = op->acc_mode; 288303da633aSAl Viro if (*opened & FILE_CREATED) { 288403da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 288503da633aSAl Viro fsnotify_create(dir, dentry); 288603da633aSAl Viro acc_mode = MAY_OPEN; 288703da633aSAl Viro } 28882675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 28892675a4ebSAl Viro if (error) 28902675a4ebSAl Viro fput(file); 2891d18e9008SMiklos Szeredi 2892d18e9008SMiklos Szeredi out: 2893d18e9008SMiklos Szeredi dput(dentry); 28942675a4ebSAl Viro return error; 2895d18e9008SMiklos Szeredi 2896d18e9008SMiklos Szeredi no_open: 2897d18e9008SMiklos Szeredi if (need_lookup) { 289872bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2899d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 29002675a4ebSAl Viro return PTR_ERR(dentry); 2901d18e9008SMiklos Szeredi 2902d18e9008SMiklos Szeredi if (create_error) { 2903d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2904d18e9008SMiklos Szeredi 29052675a4ebSAl Viro error = create_error; 2906d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2907d18e9008SMiklos Szeredi if (!dentry->d_inode) 2908d18e9008SMiklos Szeredi goto out; 2909d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2910d18e9008SMiklos Szeredi goto out; 2911d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2912e36cb0b8SDavid Howells d_is_reg(dentry)) { 2913d18e9008SMiklos Szeredi goto out; 2914d18e9008SMiklos Szeredi } 2915d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2916d18e9008SMiklos Szeredi } 2917d18e9008SMiklos Szeredi } 2918d18e9008SMiklos Szeredi looked_up: 2919d18e9008SMiklos Szeredi path->dentry = dentry; 2920d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 29212675a4ebSAl Viro return 1; 2922d18e9008SMiklos Szeredi } 2923d18e9008SMiklos Szeredi 292431e6b01fSNick Piggin /* 29251acf0af9SDavid Howells * Look up and maybe create and open the last component. 2926d58ffd35SMiklos Szeredi * 2927d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2928d58ffd35SMiklos Szeredi * 29291acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 29301acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 29311acf0af9SDavid Howells * 29321acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 29331acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 29341acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 29351acf0af9SDavid Howells * specified then a negative dentry may be returned. 29361acf0af9SDavid Howells * 29371acf0af9SDavid Howells * An error code is returned otherwise. 29381acf0af9SDavid Howells * 29391acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 29401acf0af9SDavid Howells * cleared otherwise prior to returning. 2941d58ffd35SMiklos Szeredi */ 29422675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 294330d90494SAl Viro struct file *file, 2944d58ffd35SMiklos Szeredi const struct open_flags *op, 294564894cf8SAl Viro bool got_write, int *opened) 2946d58ffd35SMiklos Szeredi { 2947d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 294854ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2949d58ffd35SMiklos Szeredi struct dentry *dentry; 2950d58ffd35SMiklos Szeredi int error; 295154ef4872SMiklos Szeredi bool need_lookup; 2952d58ffd35SMiklos Szeredi 295347237687SAl Viro *opened &= ~FILE_CREATED; 2954201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2955d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 29562675a4ebSAl Viro return PTR_ERR(dentry); 2957d58ffd35SMiklos Szeredi 2958d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2959d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2960d18e9008SMiklos Szeredi goto out_no_open; 2961d18e9008SMiklos Szeredi 2962d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 296364894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 296447237687SAl Viro need_lookup, opened); 2965d18e9008SMiklos Szeredi } 2966d18e9008SMiklos Szeredi 296754ef4872SMiklos Szeredi if (need_lookup) { 296854ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 296954ef4872SMiklos Szeredi 297072bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 297154ef4872SMiklos Szeredi if (IS_ERR(dentry)) 29722675a4ebSAl Viro return PTR_ERR(dentry); 297354ef4872SMiklos Szeredi } 297454ef4872SMiklos Szeredi 2975d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2976d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2977d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2978d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2979d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2980d58ffd35SMiklos Szeredi /* 2981d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2982d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2983d58ffd35SMiklos Szeredi * the time when the file is created and when 2984d58ffd35SMiklos Szeredi * a permanent write count is taken through 2985015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 2986d58ffd35SMiklos Szeredi */ 298764894cf8SAl Viro if (!got_write) { 298864894cf8SAl Viro error = -EROFS; 2989d58ffd35SMiklos Szeredi goto out_dput; 299064894cf8SAl Viro } 299147237687SAl Viro *opened |= FILE_CREATED; 2992d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2993d58ffd35SMiklos Szeredi if (error) 2994d58ffd35SMiklos Szeredi goto out_dput; 2995312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 2996312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 2997d58ffd35SMiklos Szeredi if (error) 2998d58ffd35SMiklos Szeredi goto out_dput; 2999d58ffd35SMiklos Szeredi } 3000d18e9008SMiklos Szeredi out_no_open: 3001d58ffd35SMiklos Szeredi path->dentry = dentry; 3002d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 30032675a4ebSAl Viro return 1; 3004d58ffd35SMiklos Szeredi 3005d58ffd35SMiklos Szeredi out_dput: 3006d58ffd35SMiklos Szeredi dput(dentry); 30072675a4ebSAl Viro return error; 3008d58ffd35SMiklos Szeredi } 3009d58ffd35SMiklos Szeredi 3010d58ffd35SMiklos Szeredi /* 3011fe2d35ffSAl Viro * Handle the last step of open() 301231e6b01fSNick Piggin */ 3013896475d5SAl Viro static int do_last(struct nameidata *nd, 301430d90494SAl Viro struct file *file, const struct open_flags *op, 301576ae2a5aSAl Viro int *opened) 3016fb1cc555SAl Viro { 3017a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3018ca344a89SAl Viro int open_flag = op->open_flag; 301977d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 302064894cf8SAl Viro bool got_write = false; 3021bcda7652SAl Viro int acc_mode = op->acc_mode; 3022254cf582SAl Viro unsigned seq; 3023a1eb3315SMiklos Szeredi struct inode *inode; 302416b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 3025896475d5SAl Viro struct path path; 302616b1c1cdSMiklos Szeredi bool retried = false; 302716c2cd71SAl Viro int error; 3028fb1cc555SAl Viro 3029c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3030c3e380b0SAl Viro nd->flags |= op->intent; 3031c3e380b0SAl Viro 3032bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3033fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3034deb106c6SAl Viro if (unlikely(error)) 30352675a4ebSAl Viro return error; 3036e83db167SMiklos Szeredi goto finish_open; 30371f36f774SAl Viro } 3038a2c36b45SAl Viro 3039ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3040fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3041fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3042fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3043254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 304471574865SMiklos Szeredi if (likely(!error)) 304571574865SMiklos Szeredi goto finish_lookup; 304671574865SMiklos Szeredi 3047ce57dfc1SAl Viro if (error < 0) 3048deb106c6SAl Viro return error; 3049a1eb3315SMiklos Szeredi 305037d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 3051b6183df7SMiklos Szeredi } else { 3052fe2d35ffSAl Viro /* create side of things */ 3053a3fbbde7SAl Viro /* 3054b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3055b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3056b6183df7SMiklos Szeredi * about to look up 3057a3fbbde7SAl Viro */ 30589f1fafeeSAl Viro error = complete_walk(nd); 3059e8bb73dfSAl Viro if (error) 30602675a4ebSAl Viro return error; 3061fe2d35ffSAl Viro 306276ae2a5aSAl Viro audit_inode(nd->name, dir, LOOKUP_PARENT); 30631f36f774SAl Viro /* trailing slashes? */ 3064deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3065deb106c6SAl Viro return -EISDIR; 3066b6183df7SMiklos Szeredi } 30671f36f774SAl Viro 306816b1c1cdSMiklos Szeredi retry_lookup: 306964894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 307064894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 307164894cf8SAl Viro if (!error) 307264894cf8SAl Viro got_write = true; 307364894cf8SAl Viro /* 307464894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 307564894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 307664894cf8SAl Viro * dropping this one anyway. 307764894cf8SAl Viro */ 307864894cf8SAl Viro } 3079a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 3080896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 3081fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 3082fb1cc555SAl Viro 30832675a4ebSAl Viro if (error <= 0) { 30842675a4ebSAl Viro if (error) 3085d58ffd35SMiklos Szeredi goto out; 30866c0d46c4SAl Viro 308747237687SAl Viro if ((*opened & FILE_CREATED) || 3088496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 308977d660a8SMiklos Szeredi will_truncate = false; 3090d18e9008SMiklos Szeredi 309176ae2a5aSAl Viro audit_inode(nd->name, file->f_path.dentry, 0); 3092d18e9008SMiklos Szeredi goto opened; 3093d18e9008SMiklos Szeredi } 3094d18e9008SMiklos Szeredi 309547237687SAl Viro if (*opened & FILE_CREATED) { 30969b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3097ca344a89SAl Viro open_flag &= ~O_TRUNC; 309877d660a8SMiklos Szeredi will_truncate = false; 3099bcda7652SAl Viro acc_mode = MAY_OPEN; 3100896475d5SAl Viro path_to_nameidata(&path, nd); 3101e83db167SMiklos Szeredi goto finish_open_created; 3102fb1cc555SAl Viro } 3103fb1cc555SAl Viro 3104fb1cc555SAl Viro /* 31053134f37eSJeff Layton * create/update audit record if it already exists. 3106fb1cc555SAl Viro */ 3107896475d5SAl Viro if (d_is_positive(path.dentry)) 310876ae2a5aSAl Viro audit_inode(nd->name, path.dentry, 0); 3109fb1cc555SAl Viro 3110d18e9008SMiklos Szeredi /* 3111d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3112d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3113d18e9008SMiklos Szeredi * necessary...) 3114d18e9008SMiklos Szeredi */ 311564894cf8SAl Viro if (got_write) { 3116d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 311764894cf8SAl Viro got_write = false; 3118d18e9008SMiklos Szeredi } 3119d18e9008SMiklos Szeredi 3120deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3121deb106c6SAl Viro path_to_nameidata(&path, nd); 3122deb106c6SAl Viro return -EEXIST; 3123deb106c6SAl Viro } 3124fb1cc555SAl Viro 3125756daf26SNeilBrown error = follow_managed(&path, nd); 3126deb106c6SAl Viro if (unlikely(error < 0)) 3127deb106c6SAl Viro return error; 3128a3fbbde7SAl Viro 3129decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 313063afdfc7SDavid Howells inode = d_backing_inode(path.dentry); 3131254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3132deb106c6SAl Viro if (unlikely(d_is_negative(path.dentry))) { 3133896475d5SAl Viro path_to_nameidata(&path, nd); 3134deb106c6SAl Viro return -ENOENT; 313554c33e7fSMiklos Szeredi } 3136766c4cbfSAl Viro finish_lookup: 3137191d7f73SAl Viro if (nd->depth) 3138191d7f73SAl Viro put_link(nd); 3139181548c0SAl Viro error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW, 3140181548c0SAl Viro inode, seq); 3141deb106c6SAl Viro if (unlikely(error)) 3142d63ff28fSAl Viro return error; 3143fb1cc555SAl Viro 3144896475d5SAl Viro if (unlikely(d_is_symlink(path.dentry)) && !(open_flag & O_PATH)) { 3145896475d5SAl Viro path_to_nameidata(&path, nd); 3146deb106c6SAl Viro return -ELOOP; 3147a5cfe2d5SAl Viro } 3148a5cfe2d5SAl Viro 3149896475d5SAl Viro if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { 3150896475d5SAl Viro path_to_nameidata(&path, nd); 315116b1c1cdSMiklos Szeredi } else { 315216b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 3153896475d5SAl Viro save_parent.mnt = mntget(path.mnt); 3154896475d5SAl Viro nd->path.dentry = path.dentry; 315516b1c1cdSMiklos Szeredi 315616b1c1cdSMiklos Szeredi } 3157decf3400SMiklos Szeredi nd->inode = inode; 3158254cf582SAl Viro nd->seq = seq; 3159a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3160bc77daa7SAl Viro finish_open: 3161a3fbbde7SAl Viro error = complete_walk(nd); 316216b1c1cdSMiklos Szeredi if (error) { 316316b1c1cdSMiklos Szeredi path_put(&save_parent); 31642675a4ebSAl Viro return error; 316516b1c1cdSMiklos Szeredi } 316676ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 3167fb1cc555SAl Viro error = -EISDIR; 316844b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 31692675a4ebSAl Viro goto out; 3170af2f5542SMiklos Szeredi error = -ENOTDIR; 317144b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 31722675a4ebSAl Viro goto out; 31734bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 317477d660a8SMiklos Szeredi will_truncate = false; 31756c0d46c4SAl Viro 31760f9d1a10SAl Viro if (will_truncate) { 31770f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 31780f9d1a10SAl Viro if (error) 31792675a4ebSAl Viro goto out; 318064894cf8SAl Viro got_write = true; 31810f9d1a10SAl Viro } 3182e83db167SMiklos Szeredi finish_open_created: 3183bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3184ca344a89SAl Viro if (error) 31852675a4ebSAl Viro goto out; 31864aa7c634SMiklos Szeredi 31874aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 31884aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 31894aa7c634SMiklos Szeredi if (!error) { 31904aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 31914aa7c634SMiklos Szeredi } else { 319230d90494SAl Viro if (error == -EOPENSTALE) 3193f60dc3dbSMiklos Szeredi goto stale_open; 3194015c3bbcSMiklos Szeredi goto out; 3195f60dc3dbSMiklos Szeredi } 3196a8277b9bSMiklos Szeredi opened: 31972675a4ebSAl Viro error = open_check_o_direct(file); 3198015c3bbcSMiklos Szeredi if (error) 3199015c3bbcSMiklos Szeredi goto exit_fput; 32003034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3201aa4caadbSMiklos Szeredi if (error) 3202aa4caadbSMiklos Szeredi goto exit_fput; 3203aa4caadbSMiklos Szeredi 32040f9d1a10SAl Viro if (will_truncate) { 32052675a4ebSAl Viro error = handle_truncate(file); 3206aa4caadbSMiklos Szeredi if (error) 3207aa4caadbSMiklos Szeredi goto exit_fput; 32080f9d1a10SAl Viro } 3209ca344a89SAl Viro out: 321064894cf8SAl Viro if (got_write) 32110f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 321216b1c1cdSMiklos Szeredi path_put(&save_parent); 32132675a4ebSAl Viro return error; 3214fb1cc555SAl Viro 3215015c3bbcSMiklos Szeredi exit_fput: 32162675a4ebSAl Viro fput(file); 32172675a4ebSAl Viro goto out; 3218015c3bbcSMiklos Szeredi 3219f60dc3dbSMiklos Szeredi stale_open: 3220f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3221f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3222f60dc3dbSMiklos Szeredi goto out; 3223f60dc3dbSMiklos Szeredi 3224f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3225f60dc3dbSMiklos Szeredi path_put(&nd->path); 3226f60dc3dbSMiklos Szeredi nd->path = save_parent; 3227f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3228f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3229f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 323064894cf8SAl Viro if (got_write) { 3231f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 323264894cf8SAl Viro got_write = false; 3233f60dc3dbSMiklos Szeredi } 3234f60dc3dbSMiklos Szeredi retried = true; 3235f60dc3dbSMiklos Szeredi goto retry_lookup; 3236fb1cc555SAl Viro } 3237fb1cc555SAl Viro 3238c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 323960545d0dSAl Viro const struct open_flags *op, 324060545d0dSAl Viro struct file *file, int *opened) 324160545d0dSAl Viro { 324260545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 3243625b6d10SAl Viro struct dentry *child; 324460545d0dSAl Viro struct inode *dir; 3245625b6d10SAl Viro struct path path; 3246c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 324760545d0dSAl Viro if (unlikely(error)) 324860545d0dSAl Viro return error; 3249625b6d10SAl Viro error = mnt_want_write(path.mnt); 325060545d0dSAl Viro if (unlikely(error)) 325160545d0dSAl Viro goto out; 3252625b6d10SAl Viro dir = path.dentry->d_inode; 325360545d0dSAl Viro /* we want directory to be writable */ 3254625b6d10SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 325560545d0dSAl Viro if (error) 325660545d0dSAl Viro goto out2; 325760545d0dSAl Viro if (!dir->i_op->tmpfile) { 325860545d0dSAl Viro error = -EOPNOTSUPP; 325960545d0dSAl Viro goto out2; 326060545d0dSAl Viro } 3261625b6d10SAl Viro child = d_alloc(path.dentry, &name); 326260545d0dSAl Viro if (unlikely(!child)) { 326360545d0dSAl Viro error = -ENOMEM; 326460545d0dSAl Viro goto out2; 326560545d0dSAl Viro } 3266625b6d10SAl Viro dput(path.dentry); 3267625b6d10SAl Viro path.dentry = child; 3268625b6d10SAl Viro error = dir->i_op->tmpfile(dir, child, op->mode); 326960545d0dSAl Viro if (error) 327060545d0dSAl Viro goto out2; 3271c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 327269a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 3273625b6d10SAl Viro error = may_open(&path, MAY_OPEN, op->open_flag); 327460545d0dSAl Viro if (error) 327560545d0dSAl Viro goto out2; 3276625b6d10SAl Viro file->f_path.mnt = path.mnt; 3277625b6d10SAl Viro error = finish_open(file, child, NULL, opened); 327860545d0dSAl Viro if (error) 327960545d0dSAl Viro goto out2; 328060545d0dSAl Viro error = open_check_o_direct(file); 3281f4e0c30cSAl Viro if (error) { 328260545d0dSAl Viro fput(file); 3283f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3284f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3285f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3286f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3287f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3288f4e0c30cSAl Viro } 328960545d0dSAl Viro out2: 3290625b6d10SAl Viro mnt_drop_write(path.mnt); 329160545d0dSAl Viro out: 3292625b6d10SAl Viro path_put(&path); 329360545d0dSAl Viro return error; 329460545d0dSAl Viro } 329560545d0dSAl Viro 3296c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3297c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 32981da177e4SLinus Torvalds { 3299368ee9baSAl Viro const char *s; 330030d90494SAl Viro struct file *file; 330147237687SAl Viro int opened = 0; 330213aab428SAl Viro int error; 330331e6b01fSNick Piggin 330430d90494SAl Viro file = get_empty_filp(); 33051afc99beSAl Viro if (IS_ERR(file)) 33061afc99beSAl Viro return file; 330731e6b01fSNick Piggin 330830d90494SAl Viro file->f_flags = op->open_flag; 330931e6b01fSNick Piggin 3310bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 3311c8a53ee5SAl Viro error = do_tmpfile(nd, flags, op, file, &opened); 3312f15133dfSAl Viro goto out2; 331360545d0dSAl Viro } 331460545d0dSAl Viro 3315c8a53ee5SAl Viro s = path_init(nd, flags); 3316368ee9baSAl Viro if (IS_ERR(s)) { 3317368ee9baSAl Viro put_filp(file); 3318368ee9baSAl Viro return ERR_CAST(s); 3319368ee9baSAl Viro } 33203bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 332176ae2a5aSAl Viro (error = do_last(nd, file, op, &opened)) > 0) { 332273d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 33233bdba28bSAl Viro s = trailing_symlink(nd); 33243bdba28bSAl Viro if (IS_ERR(s)) { 33253bdba28bSAl Viro error = PTR_ERR(s); 33262675a4ebSAl Viro break; 3327806b681cSAl Viro } 33283bdba28bSAl Viro } 3329deb106c6SAl Viro terminate_walk(nd); 3330f15133dfSAl Viro out2: 33312675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 33322675a4ebSAl Viro BUG_ON(!error); 333330d90494SAl Viro put_filp(file); 3334015c3bbcSMiklos Szeredi } 33352675a4ebSAl Viro if (unlikely(error)) { 33362675a4ebSAl Viro if (error == -EOPENSTALE) { 33372675a4ebSAl Viro if (flags & LOOKUP_RCU) 33382675a4ebSAl Viro error = -ECHILD; 33392675a4ebSAl Viro else 33402675a4ebSAl Viro error = -ESTALE; 33412675a4ebSAl Viro } 33422675a4ebSAl Viro file = ERR_PTR(error); 33432675a4ebSAl Viro } 33442675a4ebSAl Viro return file; 3345de459215SKirill Korotaev } 33461da177e4SLinus Torvalds 3347669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3348f9652e10SAl Viro const struct open_flags *op) 334913aab428SAl Viro { 33509883d185SAl Viro struct nameidata nd; 3351f9652e10SAl Viro int flags = op->lookup_flags; 335213aab428SAl Viro struct file *filp; 335313aab428SAl Viro 33549883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3355c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 335613aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3357c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 335813aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3359c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 33609883d185SAl Viro restore_nameidata(); 336113aab428SAl Viro return filp; 336213aab428SAl Viro } 336313aab428SAl Viro 336473d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3365f9652e10SAl Viro const char *name, const struct open_flags *op) 336673d049a4SAl Viro { 33679883d185SAl Viro struct nameidata nd; 336873d049a4SAl Viro struct file *file; 336951689104SPaul Moore struct filename *filename; 3370f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 337173d049a4SAl Viro 337273d049a4SAl Viro nd.root.mnt = mnt; 337373d049a4SAl Viro nd.root.dentry = dentry; 337473d049a4SAl Viro 3375b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 337673d049a4SAl Viro return ERR_PTR(-ELOOP); 337773d049a4SAl Viro 337851689104SPaul Moore filename = getname_kernel(name); 337951689104SPaul Moore if (unlikely(IS_ERR(filename))) 338051689104SPaul Moore return ERR_CAST(filename); 338151689104SPaul Moore 33829883d185SAl Viro set_nameidata(&nd, -1, filename); 3383c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 338473d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3385c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 338673d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3387c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 33889883d185SAl Viro restore_nameidata(); 338951689104SPaul Moore putname(filename); 339073d049a4SAl Viro return file; 339173d049a4SAl Viro } 339273d049a4SAl Viro 3393fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 33941ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 33951da177e4SLinus Torvalds { 3396c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3397391172c4SAl Viro struct qstr last; 3398391172c4SAl Viro int type; 3399c30dabfeSJan Kara int err2; 34001ac12b4bSJeff Layton int error; 34011ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 34021ac12b4bSJeff Layton 34031ac12b4bSJeff Layton /* 34041ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 34051ac12b4bSJeff Layton * other flags passed in are ignored! 34061ac12b4bSJeff Layton */ 34071ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 34081ac12b4bSJeff Layton 34095c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 34105c31b6ceSAl Viro if (IS_ERR(name)) 34115c31b6ceSAl Viro return ERR_CAST(name); 34121da177e4SLinus Torvalds 3413c663e5d8SChristoph Hellwig /* 3414c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3415c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3416c663e5d8SChristoph Hellwig */ 34175c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3418ed75e95dSAl Viro goto out; 3419c663e5d8SChristoph Hellwig 3420c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3421391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3422c663e5d8SChristoph Hellwig /* 3423c663e5d8SChristoph Hellwig * Do the final lookup. 3424c663e5d8SChristoph Hellwig */ 3425391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 3426391172c4SAl Viro mutex_lock_nested(&path->dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3427391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 34281da177e4SLinus Torvalds if (IS_ERR(dentry)) 3429a8104a9fSAl Viro goto unlock; 3430c663e5d8SChristoph Hellwig 3431a8104a9fSAl Viro error = -EEXIST; 3432b18825a7SDavid Howells if (d_is_positive(dentry)) 3433a8104a9fSAl Viro goto fail; 3434b18825a7SDavid Howells 3435c663e5d8SChristoph Hellwig /* 3436c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3437c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3438c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3439c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3440c663e5d8SChristoph Hellwig */ 3441391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3442a8104a9fSAl Viro error = -ENOENT; 3443ed75e95dSAl Viro goto fail; 3444e9baf6e5SAl Viro } 3445c30dabfeSJan Kara if (unlikely(err2)) { 3446c30dabfeSJan Kara error = err2; 3447a8104a9fSAl Viro goto fail; 3448c30dabfeSJan Kara } 3449181c37b6SAl Viro putname(name); 3450e9baf6e5SAl Viro return dentry; 34511da177e4SLinus Torvalds fail: 3452a8104a9fSAl Viro dput(dentry); 3453a8104a9fSAl Viro dentry = ERR_PTR(error); 3454a8104a9fSAl Viro unlock: 3455391172c4SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3456c30dabfeSJan Kara if (!err2) 3457391172c4SAl Viro mnt_drop_write(path->mnt); 3458ed75e95dSAl Viro out: 3459391172c4SAl Viro path_put(path); 3460181c37b6SAl Viro putname(name); 3461ed75e95dSAl Viro return dentry; 3462dae6ad8fSAl Viro } 3463fa14a0b8SAl Viro 3464fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3465fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3466fa14a0b8SAl Viro { 3467181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3468181c37b6SAl Viro path, lookup_flags); 3469fa14a0b8SAl Viro } 3470dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3471dae6ad8fSAl Viro 3472921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3473921a1650SAl Viro { 3474921a1650SAl Viro dput(dentry); 3475921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3476a8104a9fSAl Viro mnt_drop_write(path->mnt); 3477921a1650SAl Viro path_put(path); 3478921a1650SAl Viro } 3479921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3480921a1650SAl Viro 3481520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 34821ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3483dae6ad8fSAl Viro { 3484181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3485dae6ad8fSAl Viro } 3486dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3487dae6ad8fSAl Viro 34881a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 34891da177e4SLinus Torvalds { 3490a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 34911da177e4SLinus Torvalds 34921da177e4SLinus Torvalds if (error) 34931da177e4SLinus Torvalds return error; 34941da177e4SLinus Torvalds 3495975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 34961da177e4SLinus Torvalds return -EPERM; 34971da177e4SLinus Torvalds 3498acfa4380SAl Viro if (!dir->i_op->mknod) 34991da177e4SLinus Torvalds return -EPERM; 35001da177e4SLinus Torvalds 350108ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 350208ce5f16SSerge E. Hallyn if (error) 350308ce5f16SSerge E. Hallyn return error; 350408ce5f16SSerge E. Hallyn 35051da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 35061da177e4SLinus Torvalds if (error) 35071da177e4SLinus Torvalds return error; 35081da177e4SLinus Torvalds 35091da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3510a74574aaSStephen Smalley if (!error) 3511f38aa942SAmy Griffis fsnotify_create(dir, dentry); 35121da177e4SLinus Torvalds return error; 35131da177e4SLinus Torvalds } 35144d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 35151da177e4SLinus Torvalds 3516f69aac00SAl Viro static int may_mknod(umode_t mode) 3517463c3197SDave Hansen { 3518463c3197SDave Hansen switch (mode & S_IFMT) { 3519463c3197SDave Hansen case S_IFREG: 3520463c3197SDave Hansen case S_IFCHR: 3521463c3197SDave Hansen case S_IFBLK: 3522463c3197SDave Hansen case S_IFIFO: 3523463c3197SDave Hansen case S_IFSOCK: 3524463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3525463c3197SDave Hansen return 0; 3526463c3197SDave Hansen case S_IFDIR: 3527463c3197SDave Hansen return -EPERM; 3528463c3197SDave Hansen default: 3529463c3197SDave Hansen return -EINVAL; 3530463c3197SDave Hansen } 3531463c3197SDave Hansen } 3532463c3197SDave Hansen 35338208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 35342e4d0924SHeiko Carstens unsigned, dev) 35351da177e4SLinus Torvalds { 35361da177e4SLinus Torvalds struct dentry *dentry; 3537dae6ad8fSAl Viro struct path path; 3538dae6ad8fSAl Viro int error; 3539972567f1SJeff Layton unsigned int lookup_flags = 0; 35401da177e4SLinus Torvalds 35418e4bfca1SAl Viro error = may_mknod(mode); 35428e4bfca1SAl Viro if (error) 35438e4bfca1SAl Viro return error; 3544972567f1SJeff Layton retry: 3545972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3546dae6ad8fSAl Viro if (IS_ERR(dentry)) 3547dae6ad8fSAl Viro return PTR_ERR(dentry); 35482ad94ae6SAl Viro 3549dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3550ce3b0f8dSAl Viro mode &= ~current_umask(); 3551dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3552be6d3e56SKentaro Takeda if (error) 3553a8104a9fSAl Viro goto out; 35541da177e4SLinus Torvalds switch (mode & S_IFMT) { 35551da177e4SLinus Torvalds case 0: case S_IFREG: 3556312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 35571da177e4SLinus Torvalds break; 35581da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3559dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 35601da177e4SLinus Torvalds new_decode_dev(dev)); 35611da177e4SLinus Torvalds break; 35621da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3563dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 35641da177e4SLinus Torvalds break; 35651da177e4SLinus Torvalds } 3566a8104a9fSAl Viro out: 3567921a1650SAl Viro done_path_create(&path, dentry); 3568972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3569972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3570972567f1SJeff Layton goto retry; 3571972567f1SJeff Layton } 35721da177e4SLinus Torvalds return error; 35731da177e4SLinus Torvalds } 35741da177e4SLinus Torvalds 35758208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 35765590ff0dSUlrich Drepper { 35775590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 35785590ff0dSUlrich Drepper } 35795590ff0dSUlrich Drepper 358018bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 35811da177e4SLinus Torvalds { 3582a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35838de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 35841da177e4SLinus Torvalds 35851da177e4SLinus Torvalds if (error) 35861da177e4SLinus Torvalds return error; 35871da177e4SLinus Torvalds 3588acfa4380SAl Viro if (!dir->i_op->mkdir) 35891da177e4SLinus Torvalds return -EPERM; 35901da177e4SLinus Torvalds 35911da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 35921da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 35931da177e4SLinus Torvalds if (error) 35941da177e4SLinus Torvalds return error; 35951da177e4SLinus Torvalds 35968de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 35978de52778SAl Viro return -EMLINK; 35988de52778SAl Viro 35991da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3600a74574aaSStephen Smalley if (!error) 3601f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 36021da177e4SLinus Torvalds return error; 36031da177e4SLinus Torvalds } 36044d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 36051da177e4SLinus Torvalds 3606a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 36071da177e4SLinus Torvalds { 36086902d925SDave Hansen struct dentry *dentry; 3609dae6ad8fSAl Viro struct path path; 3610dae6ad8fSAl Viro int error; 3611b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 36121da177e4SLinus Torvalds 3613b76d8b82SJeff Layton retry: 3614b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 36156902d925SDave Hansen if (IS_ERR(dentry)) 3616dae6ad8fSAl Viro return PTR_ERR(dentry); 36176902d925SDave Hansen 3618dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3619ce3b0f8dSAl Viro mode &= ~current_umask(); 3620dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3621a8104a9fSAl Viro if (!error) 3622dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3623921a1650SAl Viro done_path_create(&path, dentry); 3624b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3625b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3626b76d8b82SJeff Layton goto retry; 3627b76d8b82SJeff Layton } 36281da177e4SLinus Torvalds return error; 36291da177e4SLinus Torvalds } 36301da177e4SLinus Torvalds 3631a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 36325590ff0dSUlrich Drepper { 36335590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 36345590ff0dSUlrich Drepper } 36355590ff0dSUlrich Drepper 36361da177e4SLinus Torvalds /* 3637a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3638c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3639a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3640a71905f0SSage Weil * then we drop the dentry now. 36411da177e4SLinus Torvalds * 36421da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 36431da177e4SLinus Torvalds * do a 36441da177e4SLinus Torvalds * 36451da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 36461da177e4SLinus Torvalds * return -EBUSY; 36471da177e4SLinus Torvalds * 36481da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 36491da177e4SLinus Torvalds * that is still in use by something else.. 36501da177e4SLinus Torvalds */ 36511da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 36521da177e4SLinus Torvalds { 36531da177e4SLinus Torvalds shrink_dcache_parent(dentry); 36541da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 365598474236SWaiman Long if (dentry->d_lockref.count == 1) 36561da177e4SLinus Torvalds __d_drop(dentry); 36571da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 36581da177e4SLinus Torvalds } 36594d359507SAl Viro EXPORT_SYMBOL(dentry_unhash); 36601da177e4SLinus Torvalds 36611da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 36621da177e4SLinus Torvalds { 36631da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 36641da177e4SLinus Torvalds 36651da177e4SLinus Torvalds if (error) 36661da177e4SLinus Torvalds return error; 36671da177e4SLinus Torvalds 3668acfa4380SAl Viro if (!dir->i_op->rmdir) 36691da177e4SLinus Torvalds return -EPERM; 36701da177e4SLinus Torvalds 36711d2ef590SAl Viro dget(dentry); 36721b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3673912dbc15SSage Weil 36741da177e4SLinus Torvalds error = -EBUSY; 36757af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3676912dbc15SSage Weil goto out; 3677912dbc15SSage Weil 36781da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3679912dbc15SSage Weil if (error) 3680912dbc15SSage Weil goto out; 3681912dbc15SSage Weil 36823cebde24SSage Weil shrink_dcache_parent(dentry); 36831da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3684912dbc15SSage Weil if (error) 3685912dbc15SSage Weil goto out; 3686912dbc15SSage Weil 36871da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3688d83c49f3SAl Viro dont_mount(dentry); 36898ed936b5SEric W. Biederman detach_mounts(dentry); 36901da177e4SLinus Torvalds 3691912dbc15SSage Weil out: 3692912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 36931d2ef590SAl Viro dput(dentry); 3694912dbc15SSage Weil if (!error) 3695912dbc15SSage Weil d_delete(dentry); 36961da177e4SLinus Torvalds return error; 36971da177e4SLinus Torvalds } 36984d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 36991da177e4SLinus Torvalds 37005590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 37011da177e4SLinus Torvalds { 37021da177e4SLinus Torvalds int error = 0; 370391a27b2aSJeff Layton struct filename *name; 37041da177e4SLinus Torvalds struct dentry *dentry; 3705f5beed75SAl Viro struct path path; 3706f5beed75SAl Viro struct qstr last; 3707f5beed75SAl Viro int type; 3708c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3709c6ee9206SJeff Layton retry: 3710f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3711f5beed75SAl Viro &path, &last, &type, lookup_flags); 371291a27b2aSJeff Layton if (IS_ERR(name)) 371391a27b2aSJeff Layton return PTR_ERR(name); 37141da177e4SLinus Torvalds 3715f5beed75SAl Viro switch (type) { 37161da177e4SLinus Torvalds case LAST_DOTDOT: 37171da177e4SLinus Torvalds error = -ENOTEMPTY; 37181da177e4SLinus Torvalds goto exit1; 37191da177e4SLinus Torvalds case LAST_DOT: 37201da177e4SLinus Torvalds error = -EINVAL; 37211da177e4SLinus Torvalds goto exit1; 37221da177e4SLinus Torvalds case LAST_ROOT: 37231da177e4SLinus Torvalds error = -EBUSY; 37241da177e4SLinus Torvalds goto exit1; 37251da177e4SLinus Torvalds } 37260612d9fbSOGAWA Hirofumi 3727f5beed75SAl Viro error = mnt_want_write(path.mnt); 3728c30dabfeSJan Kara if (error) 3729c30dabfeSJan Kara goto exit1; 37300612d9fbSOGAWA Hirofumi 3731f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3732f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 37331da177e4SLinus Torvalds error = PTR_ERR(dentry); 37346902d925SDave Hansen if (IS_ERR(dentry)) 37356902d925SDave Hansen goto exit2; 3736e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3737e6bc45d6STheodore Ts'o error = -ENOENT; 3738e6bc45d6STheodore Ts'o goto exit3; 3739e6bc45d6STheodore Ts'o } 3740f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3741be6d3e56SKentaro Takeda if (error) 3742c30dabfeSJan Kara goto exit3; 3743f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 37440622753bSDave Hansen exit3: 37451da177e4SLinus Torvalds dput(dentry); 37466902d925SDave Hansen exit2: 3747f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 3748f5beed75SAl Viro mnt_drop_write(path.mnt); 37491da177e4SLinus Torvalds exit1: 3750f5beed75SAl Viro path_put(&path); 37511da177e4SLinus Torvalds putname(name); 3752c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3753c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3754c6ee9206SJeff Layton goto retry; 3755c6ee9206SJeff Layton } 37561da177e4SLinus Torvalds return error; 37571da177e4SLinus Torvalds } 37581da177e4SLinus Torvalds 37593cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 37605590ff0dSUlrich Drepper { 37615590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 37625590ff0dSUlrich Drepper } 37635590ff0dSUlrich Drepper 3764b21996e3SJ. Bruce Fields /** 3765b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3766b21996e3SJ. Bruce Fields * @dir: parent directory 3767b21996e3SJ. Bruce Fields * @dentry: victim 3768b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3769b21996e3SJ. Bruce Fields * 3770b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3771b21996e3SJ. Bruce Fields * 3772b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3773b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3774b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3775b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3776b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3777b21996e3SJ. Bruce Fields * 3778b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3779b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3780b21996e3SJ. Bruce Fields * to be NFS exported. 3781b21996e3SJ. Bruce Fields */ 3782b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 37831da177e4SLinus Torvalds { 37849accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 37851da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 37861da177e4SLinus Torvalds 37871da177e4SLinus Torvalds if (error) 37881da177e4SLinus Torvalds return error; 37891da177e4SLinus Torvalds 3790acfa4380SAl Viro if (!dir->i_op->unlink) 37911da177e4SLinus Torvalds return -EPERM; 37921da177e4SLinus Torvalds 37939accbb97SJ. Bruce Fields mutex_lock(&target->i_mutex); 37948ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 37951da177e4SLinus Torvalds error = -EBUSY; 37961da177e4SLinus Torvalds else { 37971da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3798bec1052eSAl Viro if (!error) { 37995a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 38005a14696cSJ. Bruce Fields if (error) 3801b21996e3SJ. Bruce Fields goto out; 38021da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 38038ed936b5SEric W. Biederman if (!error) { 3804d83c49f3SAl Viro dont_mount(dentry); 38058ed936b5SEric W. Biederman detach_mounts(dentry); 38068ed936b5SEric W. Biederman } 3807bec1052eSAl Viro } 38081da177e4SLinus Torvalds } 3809b21996e3SJ. Bruce Fields out: 38109accbb97SJ. Bruce Fields mutex_unlock(&target->i_mutex); 38111da177e4SLinus Torvalds 38121da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 38131da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 38149accbb97SJ. Bruce Fields fsnotify_link_count(target); 38151da177e4SLinus Torvalds d_delete(dentry); 38161da177e4SLinus Torvalds } 38170eeca283SRobert Love 38181da177e4SLinus Torvalds return error; 38191da177e4SLinus Torvalds } 38204d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 38211da177e4SLinus Torvalds 38221da177e4SLinus Torvalds /* 38231da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 38241b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 38251da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 38261da177e4SLinus Torvalds * while waiting on the I/O. 38271da177e4SLinus Torvalds */ 38285590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 38291da177e4SLinus Torvalds { 38302ad94ae6SAl Viro int error; 383191a27b2aSJeff Layton struct filename *name; 38321da177e4SLinus Torvalds struct dentry *dentry; 3833f5beed75SAl Viro struct path path; 3834f5beed75SAl Viro struct qstr last; 3835f5beed75SAl Viro int type; 38361da177e4SLinus Torvalds struct inode *inode = NULL; 3837b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 38385d18f813SJeff Layton unsigned int lookup_flags = 0; 38395d18f813SJeff Layton retry: 3840f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3841f5beed75SAl Viro &path, &last, &type, lookup_flags); 384291a27b2aSJeff Layton if (IS_ERR(name)) 384391a27b2aSJeff Layton return PTR_ERR(name); 38442ad94ae6SAl Viro 38451da177e4SLinus Torvalds error = -EISDIR; 3846f5beed75SAl Viro if (type != LAST_NORM) 38471da177e4SLinus Torvalds goto exit1; 38480612d9fbSOGAWA Hirofumi 3849f5beed75SAl Viro error = mnt_want_write(path.mnt); 3850c30dabfeSJan Kara if (error) 3851c30dabfeSJan Kara goto exit1; 3852b21996e3SJ. Bruce Fields retry_deleg: 3853f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3854f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38551da177e4SLinus Torvalds error = PTR_ERR(dentry); 38561da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 38571da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3858f5beed75SAl Viro if (last.name[last.len]) 385950338b88STörök Edwin goto slashes; 38601da177e4SLinus Torvalds inode = dentry->d_inode; 3861b18825a7SDavid Howells if (d_is_negative(dentry)) 3862e6bc45d6STheodore Ts'o goto slashes; 38637de9c6eeSAl Viro ihold(inode); 3864f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3865be6d3e56SKentaro Takeda if (error) 3866c30dabfeSJan Kara goto exit2; 3867f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 38681da177e4SLinus Torvalds exit2: 38691da177e4SLinus Torvalds dput(dentry); 38701da177e4SLinus Torvalds } 3871f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 38721da177e4SLinus Torvalds if (inode) 38731da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3874b21996e3SJ. Bruce Fields inode = NULL; 3875b21996e3SJ. Bruce Fields if (delegated_inode) { 38765a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3877b21996e3SJ. Bruce Fields if (!error) 3878b21996e3SJ. Bruce Fields goto retry_deleg; 3879b21996e3SJ. Bruce Fields } 3880f5beed75SAl Viro mnt_drop_write(path.mnt); 38811da177e4SLinus Torvalds exit1: 3882f5beed75SAl Viro path_put(&path); 38831da177e4SLinus Torvalds putname(name); 38845d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 38855d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 38865d18f813SJeff Layton inode = NULL; 38875d18f813SJeff Layton goto retry; 38885d18f813SJeff Layton } 38891da177e4SLinus Torvalds return error; 38901da177e4SLinus Torvalds 38911da177e4SLinus Torvalds slashes: 3892b18825a7SDavid Howells if (d_is_negative(dentry)) 3893b18825a7SDavid Howells error = -ENOENT; 389444b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3895b18825a7SDavid Howells error = -EISDIR; 3896b18825a7SDavid Howells else 3897b18825a7SDavid Howells error = -ENOTDIR; 38981da177e4SLinus Torvalds goto exit2; 38991da177e4SLinus Torvalds } 39001da177e4SLinus Torvalds 39012e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 39025590ff0dSUlrich Drepper { 39035590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 39045590ff0dSUlrich Drepper return -EINVAL; 39055590ff0dSUlrich Drepper 39065590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 39075590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 39085590ff0dSUlrich Drepper 39095590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 39105590ff0dSUlrich Drepper } 39115590ff0dSUlrich Drepper 39123480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 39135590ff0dSUlrich Drepper { 39145590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 39155590ff0dSUlrich Drepper } 39165590ff0dSUlrich Drepper 3917db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 39181da177e4SLinus Torvalds { 3919a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 39201da177e4SLinus Torvalds 39211da177e4SLinus Torvalds if (error) 39221da177e4SLinus Torvalds return error; 39231da177e4SLinus Torvalds 3924acfa4380SAl Viro if (!dir->i_op->symlink) 39251da177e4SLinus Torvalds return -EPERM; 39261da177e4SLinus Torvalds 39271da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 39281da177e4SLinus Torvalds if (error) 39291da177e4SLinus Torvalds return error; 39301da177e4SLinus Torvalds 39311da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3932a74574aaSStephen Smalley if (!error) 3933f38aa942SAmy Griffis fsnotify_create(dir, dentry); 39341da177e4SLinus Torvalds return error; 39351da177e4SLinus Torvalds } 39364d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 39371da177e4SLinus Torvalds 39382e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 39392e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 39401da177e4SLinus Torvalds { 39412ad94ae6SAl Viro int error; 394291a27b2aSJeff Layton struct filename *from; 39436902d925SDave Hansen struct dentry *dentry; 3944dae6ad8fSAl Viro struct path path; 3945f46d3567SJeff Layton unsigned int lookup_flags = 0; 39461da177e4SLinus Torvalds 39471da177e4SLinus Torvalds from = getname(oldname); 39481da177e4SLinus Torvalds if (IS_ERR(from)) 39491da177e4SLinus Torvalds return PTR_ERR(from); 3950f46d3567SJeff Layton retry: 3951f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 39521da177e4SLinus Torvalds error = PTR_ERR(dentry); 39536902d925SDave Hansen if (IS_ERR(dentry)) 3954dae6ad8fSAl Viro goto out_putname; 39556902d925SDave Hansen 395691a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3957a8104a9fSAl Viro if (!error) 395891a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3959921a1650SAl Viro done_path_create(&path, dentry); 3960f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 3961f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 3962f46d3567SJeff Layton goto retry; 3963f46d3567SJeff Layton } 39646902d925SDave Hansen out_putname: 39651da177e4SLinus Torvalds putname(from); 39661da177e4SLinus Torvalds return error; 39671da177e4SLinus Torvalds } 39681da177e4SLinus Torvalds 39693480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 39705590ff0dSUlrich Drepper { 39715590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 39725590ff0dSUlrich Drepper } 39735590ff0dSUlrich Drepper 3974146a8595SJ. Bruce Fields /** 3975146a8595SJ. Bruce Fields * vfs_link - create a new link 3976146a8595SJ. Bruce Fields * @old_dentry: object to be linked 3977146a8595SJ. Bruce Fields * @dir: new parent 3978146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 3979146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 3980146a8595SJ. Bruce Fields * 3981146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 3982146a8595SJ. Bruce Fields * 3983146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 3984146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 3985146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 3986146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 3987146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 3988146a8595SJ. Bruce Fields * 3989146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3990146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3991146a8595SJ. Bruce Fields * to be NFS exported. 3992146a8595SJ. Bruce Fields */ 3993146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 39941da177e4SLinus Torvalds { 39951da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 39968de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 39971da177e4SLinus Torvalds int error; 39981da177e4SLinus Torvalds 39991da177e4SLinus Torvalds if (!inode) 40001da177e4SLinus Torvalds return -ENOENT; 40011da177e4SLinus Torvalds 4002a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 40031da177e4SLinus Torvalds if (error) 40041da177e4SLinus Torvalds return error; 40051da177e4SLinus Torvalds 40061da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 40071da177e4SLinus Torvalds return -EXDEV; 40081da177e4SLinus Torvalds 40091da177e4SLinus Torvalds /* 40101da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 40111da177e4SLinus Torvalds */ 40121da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 40131da177e4SLinus Torvalds return -EPERM; 4014acfa4380SAl Viro if (!dir->i_op->link) 40151da177e4SLinus Torvalds return -EPERM; 40167e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 40171da177e4SLinus Torvalds return -EPERM; 40181da177e4SLinus Torvalds 40191da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 40201da177e4SLinus Torvalds if (error) 40211da177e4SLinus Torvalds return error; 40221da177e4SLinus Torvalds 40237e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 4024aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4025f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4026aae8a97dSAneesh Kumar K.V error = -ENOENT; 40278de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 40288de52778SAl Viro error = -EMLINK; 4029146a8595SJ. Bruce Fields else { 4030146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4031146a8595SJ. Bruce Fields if (!error) 40321da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4033146a8595SJ. Bruce Fields } 4034f4e0c30cSAl Viro 4035f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4036f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4037f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4038f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4039f4e0c30cSAl Viro } 40407e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 4041e31e14ecSStephen Smalley if (!error) 40427e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 40431da177e4SLinus Torvalds return error; 40441da177e4SLinus Torvalds } 40454d359507SAl Viro EXPORT_SYMBOL(vfs_link); 40461da177e4SLinus Torvalds 40471da177e4SLinus Torvalds /* 40481da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 40491da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 40501da177e4SLinus Torvalds * newname. --KAB 40511da177e4SLinus Torvalds * 40521da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 40531da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 40541da177e4SLinus Torvalds * and other special files. --ADM 40551da177e4SLinus Torvalds */ 40562e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 40572e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 40581da177e4SLinus Torvalds { 40591da177e4SLinus Torvalds struct dentry *new_dentry; 4060dae6ad8fSAl Viro struct path old_path, new_path; 4061146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 406211a7b371SAneesh Kumar K.V int how = 0; 40631da177e4SLinus Torvalds int error; 40641da177e4SLinus Torvalds 406511a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4066c04030e1SUlrich Drepper return -EINVAL; 406711a7b371SAneesh Kumar K.V /* 4068f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4069f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4070f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 407111a7b371SAneesh Kumar K.V */ 4072f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4073f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4074f0cc6ffbSLinus Torvalds return -ENOENT; 407511a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4076f0cc6ffbSLinus Torvalds } 4077c04030e1SUlrich Drepper 407811a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 407911a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4080442e31caSJeff Layton retry: 408111a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 40821da177e4SLinus Torvalds if (error) 40832ad94ae6SAl Viro return error; 40842ad94ae6SAl Viro 4085442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4086442e31caSJeff Layton (how & LOOKUP_REVAL)); 40871da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 40886902d925SDave Hansen if (IS_ERR(new_dentry)) 4089dae6ad8fSAl Viro goto out; 4090dae6ad8fSAl Viro 4091dae6ad8fSAl Viro error = -EXDEV; 4092dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4093dae6ad8fSAl Viro goto out_dput; 4094800179c9SKees Cook error = may_linkat(&old_path); 4095800179c9SKees Cook if (unlikely(error)) 4096800179c9SKees Cook goto out_dput; 4097dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4098be6d3e56SKentaro Takeda if (error) 4099a8104a9fSAl Viro goto out_dput; 4100146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 410175c3f29dSDave Hansen out_dput: 4102921a1650SAl Viro done_path_create(&new_path, new_dentry); 4103146a8595SJ. Bruce Fields if (delegated_inode) { 4104146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4105d22e6338SOleg Drokin if (!error) { 4106d22e6338SOleg Drokin path_put(&old_path); 4107146a8595SJ. Bruce Fields goto retry; 4108146a8595SJ. Bruce Fields } 4109d22e6338SOleg Drokin } 4110442e31caSJeff Layton if (retry_estale(error, how)) { 4111d22e6338SOleg Drokin path_put(&old_path); 4112442e31caSJeff Layton how |= LOOKUP_REVAL; 4113442e31caSJeff Layton goto retry; 4114442e31caSJeff Layton } 41151da177e4SLinus Torvalds out: 41162d8f3038SAl Viro path_put(&old_path); 41171da177e4SLinus Torvalds 41181da177e4SLinus Torvalds return error; 41191da177e4SLinus Torvalds } 41201da177e4SLinus Torvalds 41213480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 41225590ff0dSUlrich Drepper { 4123c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 41245590ff0dSUlrich Drepper } 41255590ff0dSUlrich Drepper 4126bc27027aSMiklos Szeredi /** 4127bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4128bc27027aSMiklos Szeredi * @old_dir: parent of source 4129bc27027aSMiklos Szeredi * @old_dentry: source 4130bc27027aSMiklos Szeredi * @new_dir: parent of destination 4131bc27027aSMiklos Szeredi * @new_dentry: destination 4132bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4133520c8b16SMiklos Szeredi * @flags: rename flags 4134bc27027aSMiklos Szeredi * 4135bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4136bc27027aSMiklos Szeredi * 4137bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4138bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4139bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4140bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4141bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4142bc27027aSMiklos Szeredi * so. 4143bc27027aSMiklos Szeredi * 4144bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4145bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4146bc27027aSMiklos Szeredi * to be NFS exported. 4147bc27027aSMiklos Szeredi * 41481da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 41491da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 41501da177e4SLinus Torvalds * Problems: 4151d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 41521da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 41531da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4154a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 41551da177e4SLinus Torvalds * story. 41566cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 41576cedba89SJ. Bruce Fields * and source (if it is not a directory). 41581b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 41591da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 41601da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4161a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 41621da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 41631da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 41641da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4165a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 41661da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 41671da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 41681da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4169e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 41701b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 41711da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4172c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 41731da177e4SLinus Torvalds * locking]. 41741da177e4SLinus Torvalds */ 41751da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 41768e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4177520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 41781da177e4SLinus Torvalds { 41791da177e4SLinus Torvalds int error; 4180bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 418159b0df21SEric Paris const unsigned char *old_name; 4182bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4183bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4184da1ce067SMiklos Szeredi bool new_is_dir = false; 4185da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 41861da177e4SLinus Torvalds 4187bc27027aSMiklos Szeredi if (source == target) 41881da177e4SLinus Torvalds return 0; 41891da177e4SLinus Torvalds 41901da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 41911da177e4SLinus Torvalds if (error) 41921da177e4SLinus Torvalds return error; 41931da177e4SLinus Torvalds 4194da1ce067SMiklos Szeredi if (!target) { 4195a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4196da1ce067SMiklos Szeredi } else { 4197da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4198da1ce067SMiklos Szeredi 4199da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 42001da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4201da1ce067SMiklos Szeredi else 4202da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4203da1ce067SMiklos Szeredi } 42041da177e4SLinus Torvalds if (error) 42051da177e4SLinus Torvalds return error; 42061da177e4SLinus Torvalds 42077177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 42081da177e4SLinus Torvalds return -EPERM; 42091da177e4SLinus Torvalds 4210520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4211520c8b16SMiklos Szeredi return -EINVAL; 4212520c8b16SMiklos Szeredi 4213bc27027aSMiklos Szeredi /* 4214bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4215bc27027aSMiklos Szeredi * we'll need to flip '..'. 4216bc27027aSMiklos Szeredi */ 4217da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4218da1ce067SMiklos Szeredi if (is_dir) { 4219bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4220bc27027aSMiklos Szeredi if (error) 4221bc27027aSMiklos Szeredi return error; 4222bc27027aSMiklos Szeredi } 4223da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4224da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4225da1ce067SMiklos Szeredi if (error) 4226da1ce067SMiklos Szeredi return error; 4227da1ce067SMiklos Szeredi } 4228da1ce067SMiklos Szeredi } 42290eeca283SRobert Love 42300b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 42310b3974ebSMiklos Szeredi flags); 4232bc27027aSMiklos Szeredi if (error) 4233bc27027aSMiklos Szeredi return error; 4234bc27027aSMiklos Szeredi 4235bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4236bc27027aSMiklos Szeredi dget(new_dentry); 4237da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4238bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4239bc27027aSMiklos Szeredi else if (target) 4240bc27027aSMiklos Szeredi mutex_lock(&target->i_mutex); 4241bc27027aSMiklos Szeredi 4242bc27027aSMiklos Szeredi error = -EBUSY; 42437af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4244bc27027aSMiklos Szeredi goto out; 4245bc27027aSMiklos Szeredi 4246da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4247bc27027aSMiklos Szeredi error = -EMLINK; 4248da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4249bc27027aSMiklos Szeredi goto out; 4250da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4251da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4252da1ce067SMiklos Szeredi goto out; 4253da1ce067SMiklos Szeredi } 4254da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4255bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4256da1ce067SMiklos Szeredi if (!is_dir) { 4257bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4258bc27027aSMiklos Szeredi if (error) 4259bc27027aSMiklos Szeredi goto out; 4260da1ce067SMiklos Szeredi } 4261da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4262bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4263bc27027aSMiklos Szeredi if (error) 4264bc27027aSMiklos Szeredi goto out; 4265bc27027aSMiklos Szeredi } 42667177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4267520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4268520c8b16SMiklos Szeredi new_dir, new_dentry); 4269520c8b16SMiklos Szeredi } else { 42707177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4271520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4272520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4273520c8b16SMiklos Szeredi } 4274bc27027aSMiklos Szeredi if (error) 4275bc27027aSMiklos Szeredi goto out; 4276bc27027aSMiklos Szeredi 4277da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 42781da177e4SLinus Torvalds if (is_dir) 4279bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4280bc27027aSMiklos Szeredi dont_mount(new_dentry); 42818ed936b5SEric W. Biederman detach_mounts(new_dentry); 4282bc27027aSMiklos Szeredi } 4283da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4284da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4285bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4286da1ce067SMiklos Szeredi else 4287da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4288da1ce067SMiklos Szeredi } 4289bc27027aSMiklos Szeredi out: 4290da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4291bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4292bc27027aSMiklos Szeredi else if (target) 4293bc27027aSMiklos Szeredi mutex_unlock(&target->i_mutex); 4294bc27027aSMiklos Szeredi dput(new_dentry); 4295da1ce067SMiklos Szeredi if (!error) { 4296123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4297da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4298da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4299da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4300da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4301da1ce067SMiklos Szeredi } 4302da1ce067SMiklos Szeredi } 43030eeca283SRobert Love fsnotify_oldname_free(old_name); 43040eeca283SRobert Love 43051da177e4SLinus Torvalds return error; 43061da177e4SLinus Torvalds } 43074d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 43081da177e4SLinus Torvalds 4309520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4310520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 43111da177e4SLinus Torvalds { 43121da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 43131da177e4SLinus Torvalds struct dentry *trap; 4314f5beed75SAl Viro struct path old_path, new_path; 4315f5beed75SAl Viro struct qstr old_last, new_last; 4316f5beed75SAl Viro int old_type, new_type; 43178e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 431891a27b2aSJeff Layton struct filename *from; 431991a27b2aSJeff Layton struct filename *to; 4320f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4321c6a94284SJeff Layton bool should_retry = false; 43222ad94ae6SAl Viro int error; 4323520c8b16SMiklos Szeredi 43240d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4325da1ce067SMiklos Szeredi return -EINVAL; 4326da1ce067SMiklos Szeredi 43270d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 43280d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4329520c8b16SMiklos Szeredi return -EINVAL; 4330520c8b16SMiklos Szeredi 43310d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 43320d7a8555SMiklos Szeredi return -EPERM; 43330d7a8555SMiklos Szeredi 4334f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4335f5beed75SAl Viro target_flags = 0; 4336f5beed75SAl Viro 4337c6a94284SJeff Layton retry: 4338f5beed75SAl Viro from = user_path_parent(olddfd, oldname, 4339f5beed75SAl Viro &old_path, &old_last, &old_type, lookup_flags); 434091a27b2aSJeff Layton if (IS_ERR(from)) { 434191a27b2aSJeff Layton error = PTR_ERR(from); 43421da177e4SLinus Torvalds goto exit; 434391a27b2aSJeff Layton } 43441da177e4SLinus Torvalds 4345f5beed75SAl Viro to = user_path_parent(newdfd, newname, 4346f5beed75SAl Viro &new_path, &new_last, &new_type, lookup_flags); 434791a27b2aSJeff Layton if (IS_ERR(to)) { 434891a27b2aSJeff Layton error = PTR_ERR(to); 43491da177e4SLinus Torvalds goto exit1; 435091a27b2aSJeff Layton } 43511da177e4SLinus Torvalds 43521da177e4SLinus Torvalds error = -EXDEV; 4353f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 43541da177e4SLinus Torvalds goto exit2; 43551da177e4SLinus Torvalds 43561da177e4SLinus Torvalds error = -EBUSY; 4357f5beed75SAl Viro if (old_type != LAST_NORM) 43581da177e4SLinus Torvalds goto exit2; 43591da177e4SLinus Torvalds 43600a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 43610a7c3937SMiklos Szeredi error = -EEXIST; 4362f5beed75SAl Viro if (new_type != LAST_NORM) 43631da177e4SLinus Torvalds goto exit2; 43641da177e4SLinus Torvalds 4365f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4366c30dabfeSJan Kara if (error) 4367c30dabfeSJan Kara goto exit2; 4368c30dabfeSJan Kara 43698e6d782cSJ. Bruce Fields retry_deleg: 4370f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 43711da177e4SLinus Torvalds 4372f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 43731da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 43741da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 43751da177e4SLinus Torvalds goto exit3; 43761da177e4SLinus Torvalds /* source must exist */ 43771da177e4SLinus Torvalds error = -ENOENT; 4378b18825a7SDavid Howells if (d_is_negative(old_dentry)) 43791da177e4SLinus Torvalds goto exit4; 4380f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 43811da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 43821da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 43831da177e4SLinus Torvalds goto exit4; 43840a7c3937SMiklos Szeredi error = -EEXIST; 43850a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 43860a7c3937SMiklos Szeredi goto exit5; 4387da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4388da1ce067SMiklos Szeredi error = -ENOENT; 4389da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4390da1ce067SMiklos Szeredi goto exit5; 4391da1ce067SMiklos Szeredi 4392da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4393da1ce067SMiklos Szeredi error = -ENOTDIR; 4394f5beed75SAl Viro if (new_last.name[new_last.len]) 4395da1ce067SMiklos Szeredi goto exit5; 4396da1ce067SMiklos Szeredi } 4397da1ce067SMiklos Szeredi } 43980a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 43990a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 44000a7c3937SMiklos Szeredi error = -ENOTDIR; 4401f5beed75SAl Viro if (old_last.name[old_last.len]) 44020a7c3937SMiklos Szeredi goto exit5; 4403f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 44040a7c3937SMiklos Szeredi goto exit5; 44050a7c3937SMiklos Szeredi } 44060a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 44070a7c3937SMiklos Szeredi error = -EINVAL; 44080a7c3937SMiklos Szeredi if (old_dentry == trap) 44090a7c3937SMiklos Szeredi goto exit5; 44101da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4411da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 44121da177e4SLinus Torvalds error = -ENOTEMPTY; 44131da177e4SLinus Torvalds if (new_dentry == trap) 44141da177e4SLinus Torvalds goto exit5; 44151da177e4SLinus Torvalds 4416f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4417f5beed75SAl Viro &new_path, new_dentry, flags); 4418be6d3e56SKentaro Takeda if (error) 4419c30dabfeSJan Kara goto exit5; 4420f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4421f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4422520c8b16SMiklos Szeredi &delegated_inode, flags); 44231da177e4SLinus Torvalds exit5: 44241da177e4SLinus Torvalds dput(new_dentry); 44251da177e4SLinus Torvalds exit4: 44261da177e4SLinus Torvalds dput(old_dentry); 44271da177e4SLinus Torvalds exit3: 4428f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 44298e6d782cSJ. Bruce Fields if (delegated_inode) { 44308e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 44318e6d782cSJ. Bruce Fields if (!error) 44328e6d782cSJ. Bruce Fields goto retry_deleg; 44338e6d782cSJ. Bruce Fields } 4434f5beed75SAl Viro mnt_drop_write(old_path.mnt); 44351da177e4SLinus Torvalds exit2: 4436c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4437c6a94284SJeff Layton should_retry = true; 4438f5beed75SAl Viro path_put(&new_path); 44392ad94ae6SAl Viro putname(to); 44401da177e4SLinus Torvalds exit1: 4441f5beed75SAl Viro path_put(&old_path); 44421da177e4SLinus Torvalds putname(from); 4443c6a94284SJeff Layton if (should_retry) { 4444c6a94284SJeff Layton should_retry = false; 4445c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4446c6a94284SJeff Layton goto retry; 4447c6a94284SJeff Layton } 44482ad94ae6SAl Viro exit: 44491da177e4SLinus Torvalds return error; 44501da177e4SLinus Torvalds } 44511da177e4SLinus Torvalds 4452520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4453520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4454520c8b16SMiklos Szeredi { 4455520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4456520c8b16SMiklos Szeredi } 4457520c8b16SMiklos Szeredi 4458a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 44595590ff0dSUlrich Drepper { 4460520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 44615590ff0dSUlrich Drepper } 44625590ff0dSUlrich Drepper 4463787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4464787fb6bcSMiklos Szeredi { 4465787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4466787fb6bcSMiklos Szeredi if (error) 4467787fb6bcSMiklos Szeredi return error; 4468787fb6bcSMiklos Szeredi 4469787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4470787fb6bcSMiklos Szeredi return -EPERM; 4471787fb6bcSMiklos Szeredi 4472787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4473787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4474787fb6bcSMiklos Szeredi } 4475787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4476787fb6bcSMiklos Szeredi 44775d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 44781da177e4SLinus Torvalds { 44795d826c84SAl Viro int len = PTR_ERR(link); 44801da177e4SLinus Torvalds if (IS_ERR(link)) 44811da177e4SLinus Torvalds goto out; 44821da177e4SLinus Torvalds 44831da177e4SLinus Torvalds len = strlen(link); 44841da177e4SLinus Torvalds if (len > (unsigned) buflen) 44851da177e4SLinus Torvalds len = buflen; 44861da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 44871da177e4SLinus Torvalds len = -EFAULT; 44881da177e4SLinus Torvalds out: 44891da177e4SLinus Torvalds return len; 44901da177e4SLinus Torvalds } 44915d826c84SAl Viro EXPORT_SYMBOL(readlink_copy); 44921da177e4SLinus Torvalds 44931da177e4SLinus Torvalds /* 44941da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 44951da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 44961da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 44971da177e4SLinus Torvalds */ 44981da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44991da177e4SLinus Torvalds { 4500cc314eefSLinus Torvalds void *cookie; 45015f2c4179SAl Viro struct inode *inode = d_inode(dentry); 45025f2c4179SAl Viro const char *link = inode->i_link; 4503694a1764SMarcin Slusarz int res; 4504cc314eefSLinus Torvalds 4505d4dee48bSAl Viro if (!link) { 45065f2c4179SAl Viro link = inode->i_op->follow_link(dentry, &cookie); 4507680baacbSAl Viro if (IS_ERR(link)) 4508680baacbSAl Viro return PTR_ERR(link); 4509d4dee48bSAl Viro } 4510680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 45115f2c4179SAl Viro if (inode->i_op->put_link) 45125f2c4179SAl Viro inode->i_op->put_link(inode, cookie); 4513694a1764SMarcin Slusarz return res; 45141da177e4SLinus Torvalds } 45154d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 45161da177e4SLinus Torvalds 45171da177e4SLinus Torvalds /* get the link contents into pagecache */ 45181da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 45191da177e4SLinus Torvalds { 4520ebd09abbSDuane Griffin char *kaddr; 45211da177e4SLinus Torvalds struct page *page; 45221da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 4523090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 45241da177e4SLinus Torvalds if (IS_ERR(page)) 45256fe6900eSNick Piggin return (char*)page; 45261da177e4SLinus Torvalds *ppage = page; 4527ebd09abbSDuane Griffin kaddr = kmap(page); 4528ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 4529ebd09abbSDuane Griffin return kaddr; 45301da177e4SLinus Torvalds } 45311da177e4SLinus Torvalds 45321da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 45331da177e4SLinus Torvalds { 45341da177e4SLinus Torvalds struct page *page = NULL; 45355d826c84SAl Viro int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); 45361da177e4SLinus Torvalds if (page) { 45371da177e4SLinus Torvalds kunmap(page); 45381da177e4SLinus Torvalds page_cache_release(page); 45391da177e4SLinus Torvalds } 45401da177e4SLinus Torvalds return res; 45411da177e4SLinus Torvalds } 45424d359507SAl Viro EXPORT_SYMBOL(page_readlink); 45431da177e4SLinus Torvalds 45446e77137bSAl Viro const char *page_follow_link_light(struct dentry *dentry, void **cookie) 45451da177e4SLinus Torvalds { 4546cc314eefSLinus Torvalds struct page *page = NULL; 4547680baacbSAl Viro char *res = page_getlink(dentry, &page); 4548680baacbSAl Viro if (!IS_ERR(res)) 4549680baacbSAl Viro *cookie = page; 4550680baacbSAl Viro return res; 45511da177e4SLinus Torvalds } 45524d359507SAl Viro EXPORT_SYMBOL(page_follow_link_light); 45531da177e4SLinus Torvalds 45545f2c4179SAl Viro void page_put_link(struct inode *unused, void *cookie) 45551da177e4SLinus Torvalds { 4556cc314eefSLinus Torvalds struct page *page = cookie; 45571da177e4SLinus Torvalds kunmap(page); 45581da177e4SLinus Torvalds page_cache_release(page); 45591da177e4SLinus Torvalds } 45604d359507SAl Viro EXPORT_SYMBOL(page_put_link); 45611da177e4SLinus Torvalds 456254566b2cSNick Piggin /* 456354566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 456454566b2cSNick Piggin */ 456554566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 45661da177e4SLinus Torvalds { 45671da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 45680adb25d2SKirill Korotaev struct page *page; 4569afddba49SNick Piggin void *fsdata; 4570beb497abSDmitriy Monakhov int err; 45711da177e4SLinus Torvalds char *kaddr; 457254566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 457354566b2cSNick Piggin if (nofs) 457454566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 45751da177e4SLinus Torvalds 45767e53cac4SNeilBrown retry: 4577afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 457854566b2cSNick Piggin flags, &page, &fsdata); 45791da177e4SLinus Torvalds if (err) 4580afddba49SNick Piggin goto fail; 4581afddba49SNick Piggin 4582e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 45831da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 4584e8e3c3d6SCong Wang kunmap_atomic(kaddr); 4585afddba49SNick Piggin 4586afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4587afddba49SNick Piggin page, fsdata); 45881da177e4SLinus Torvalds if (err < 0) 45891da177e4SLinus Torvalds goto fail; 4590afddba49SNick Piggin if (err < len-1) 4591afddba49SNick Piggin goto retry; 4592afddba49SNick Piggin 45931da177e4SLinus Torvalds mark_inode_dirty(inode); 45941da177e4SLinus Torvalds return 0; 45951da177e4SLinus Torvalds fail: 45961da177e4SLinus Torvalds return err; 45971da177e4SLinus Torvalds } 45984d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 45991da177e4SLinus Torvalds 46000adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 46010adb25d2SKirill Korotaev { 46020adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 460354566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 46040adb25d2SKirill Korotaev } 46054d359507SAl Viro EXPORT_SYMBOL(page_symlink); 46060adb25d2SKirill Korotaev 460792e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 46081da177e4SLinus Torvalds .readlink = generic_readlink, 46091da177e4SLinus Torvalds .follow_link = page_follow_link_light, 46101da177e4SLinus Torvalds .put_link = page_put_link, 46111da177e4SLinus Torvalds }; 46121da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4613