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 563894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 564894bc8c4SAl Viro { 565da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 566894bc8c4SAl Viro return 0; 567894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 568894bc8c4SAl Viro return 0; 569894bc8c4SAl Viro return __nd_alloc_stack(nd); 570894bc8c4SAl Viro } 571894bc8c4SAl Viro 5727973387aSAl Viro static void drop_links(struct nameidata *nd) 5737973387aSAl Viro { 5747973387aSAl Viro int i = nd->depth; 5757973387aSAl Viro while (i--) { 5767973387aSAl Viro struct saved *last = nd->stack + i; 5777973387aSAl Viro struct inode *inode = last->inode; 5787973387aSAl Viro if (last->cookie && inode->i_op->put_link) { 5797973387aSAl Viro inode->i_op->put_link(inode, last->cookie); 5807973387aSAl Viro last->cookie = NULL; 5817973387aSAl Viro } 5827973387aSAl Viro } 5837973387aSAl Viro } 5847973387aSAl Viro 5857973387aSAl Viro static void terminate_walk(struct nameidata *nd) 5867973387aSAl Viro { 5877973387aSAl Viro drop_links(nd); 5887973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 5897973387aSAl Viro int i; 5907973387aSAl Viro path_put(&nd->path); 5917973387aSAl Viro for (i = 0; i < nd->depth; i++) 5927973387aSAl Viro path_put(&nd->stack[i].link); 593102b8af2SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 594102b8af2SAl Viro path_put(&nd->root); 595102b8af2SAl Viro nd->root.mnt = NULL; 596102b8af2SAl Viro } 5977973387aSAl Viro } else { 5987973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 5997973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6007973387aSAl Viro nd->root.mnt = NULL; 6017973387aSAl Viro rcu_read_unlock(); 6027973387aSAl Viro } 6037973387aSAl Viro nd->depth = 0; 6047973387aSAl Viro } 6057973387aSAl Viro 6067973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 6077973387aSAl Viro static bool legitimize_path(struct nameidata *nd, 6087973387aSAl Viro struct path *path, unsigned seq) 6097973387aSAl Viro { 6107973387aSAl Viro int res = __legitimize_mnt(path->mnt, nd->m_seq); 6117973387aSAl Viro if (unlikely(res)) { 6127973387aSAl Viro if (res > 0) 6137973387aSAl Viro path->mnt = NULL; 6147973387aSAl Viro path->dentry = NULL; 6157973387aSAl Viro return false; 6167973387aSAl Viro } 6177973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 6187973387aSAl Viro path->dentry = NULL; 6197973387aSAl Viro return false; 6207973387aSAl Viro } 6217973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6227973387aSAl Viro } 6237973387aSAl Viro 6247973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6257973387aSAl Viro { 6267973387aSAl Viro int i; 6277973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6287973387aSAl Viro struct saved *last = nd->stack + i; 6297973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6307973387aSAl Viro drop_links(nd); 6317973387aSAl Viro nd->depth = i + 1; 6327973387aSAl Viro return false; 6337973387aSAl Viro } 6347973387aSAl Viro } 6357973387aSAl Viro return true; 6367973387aSAl Viro } 6377973387aSAl Viro 63819660af7SAl Viro /* 63931e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 64019660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 64119660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 64219660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 64319660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 64419660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 64519660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 64619660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 64731e6b01fSNick Piggin */ 64831e6b01fSNick Piggin 64931e6b01fSNick Piggin /** 65019660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 65119660af7SAl Viro * @nd: nameidata pathwalk data 65219660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 6536e9918b7SAl Viro * @seq: seq number to check dentry against 65439191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 65531e6b01fSNick Piggin * 65619660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 65719660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 65819660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 6597973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6607973387aSAl Viro * terminate_walk(). 66131e6b01fSNick Piggin */ 6626e9918b7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry, unsigned seq) 66331e6b01fSNick Piggin { 66431e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 66531e6b01fSNick Piggin 66631e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 667e5c832d5SLinus Torvalds 668e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6697973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6707973387aSAl Viro goto out2; 6717973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 6727973387aSAl Viro goto out2; 6737973387aSAl Viro if (unlikely(!lockref_get_not_dead(&parent->d_lockref))) 6747973387aSAl Viro goto out1; 67548a066e7SAl Viro 67615570086SLinus Torvalds /* 67715570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 67815570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 67915570086SLinus Torvalds * 68015570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 68115570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 68215570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 68315570086SLinus Torvalds * since we checked the sequence number of the parent after we got 68415570086SLinus Torvalds * the child sequence number. So we know the parent must still 68515570086SLinus Torvalds * be valid if the child sequence number is still valid. 68615570086SLinus Torvalds */ 68719660af7SAl Viro if (!dentry) { 688e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 689e5c832d5SLinus Torvalds goto out; 69019660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 69119660af7SAl Viro } else { 692e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 693e5c832d5SLinus Torvalds goto out; 6946e9918b7SAl Viro if (read_seqcount_retry(&dentry->d_seq, seq)) 695e5c832d5SLinus Torvalds goto drop_dentry; 69619660af7SAl Viro } 697e5c832d5SLinus Torvalds 698e5c832d5SLinus Torvalds /* 699e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 700e5c832d5SLinus Torvalds * still valid and get it if required. 701e5c832d5SLinus Torvalds */ 702e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 7035a8d87e8SAl Viro if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq))) { 7045a8d87e8SAl Viro rcu_read_unlock(); 7055a8d87e8SAl Viro dput(dentry); 7065a8d87e8SAl Viro return -ECHILD; 7077973387aSAl Viro } 70831e6b01fSNick Piggin } 70931e6b01fSNick Piggin 7108b61e74fSAl Viro rcu_read_unlock(); 71131e6b01fSNick Piggin return 0; 71219660af7SAl Viro 713e5c832d5SLinus Torvalds drop_dentry: 7148b61e74fSAl Viro rcu_read_unlock(); 715e5c832d5SLinus Torvalds dput(dentry); 716d0d27277SLinus Torvalds goto drop_root_mnt; 7177973387aSAl Viro out2: 7187973387aSAl Viro nd->path.mnt = NULL; 7197973387aSAl Viro out1: 7207973387aSAl Viro nd->path.dentry = NULL; 721e5c832d5SLinus Torvalds out: 7228b61e74fSAl Viro rcu_read_unlock(); 723d0d27277SLinus Torvalds drop_root_mnt: 724d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 725d0d27277SLinus Torvalds nd->root.mnt = NULL; 72631e6b01fSNick Piggin return -ECHILD; 72731e6b01fSNick Piggin } 72831e6b01fSNick Piggin 7297973387aSAl Viro static int unlazy_link(struct nameidata *nd, struct path *link, unsigned seq) 7307973387aSAl Viro { 7317973387aSAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 7327973387aSAl Viro drop_links(nd); 7337973387aSAl Viro nd->depth = 0; 7347973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 7357973387aSAl Viro nd->path.mnt = NULL; 7367973387aSAl Viro nd->path.dentry = NULL; 7377973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7387973387aSAl Viro nd->root.mnt = NULL; 7397973387aSAl Viro rcu_read_unlock(); 7407973387aSAl Viro } else if (likely(unlazy_walk(nd, NULL, 0)) == 0) { 7417973387aSAl Viro return 0; 7427973387aSAl Viro } 7437973387aSAl Viro path_put(link); 7447973387aSAl Viro return -ECHILD; 7457973387aSAl Viro } 7467973387aSAl Viro 7474ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 74834286d66SNick Piggin { 7494ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 75034286d66SNick Piggin } 75134286d66SNick Piggin 7529f1fafeeSAl Viro /** 7539f1fafeeSAl Viro * complete_walk - successful completion of path walk 7549f1fafeeSAl Viro * @nd: pointer nameidata 75539159de2SJeff Layton * 7569f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7579f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7589f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7599f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7609f1fafeeSAl Viro * need to drop nd->path. 76139159de2SJeff Layton */ 7629f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 76339159de2SJeff Layton { 76416c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 76539159de2SJeff Layton int status; 76639159de2SJeff Layton 7679f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 7689f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7699f1fafeeSAl Viro nd->root.mnt = NULL; 7706e9918b7SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 77148a066e7SAl Viro return -ECHILD; 77248a066e7SAl Viro } 7739f1fafeeSAl Viro 77416c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 77539159de2SJeff Layton return 0; 77639159de2SJeff Layton 777ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 77816c2cd71SAl Viro return 0; 77916c2cd71SAl Viro 780ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 78139159de2SJeff Layton if (status > 0) 78239159de2SJeff Layton return 0; 78339159de2SJeff Layton 78416c2cd71SAl Viro if (!status) 78539159de2SJeff Layton status = -ESTALE; 78616c2cd71SAl Viro 78739159de2SJeff Layton return status; 78839159de2SJeff Layton } 78939159de2SJeff Layton 79018d8c860SAl Viro static void set_root(struct nameidata *nd) 7912a737871SAl Viro { 792f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 7932a737871SAl Viro } 7942a737871SAl Viro 79518d8c860SAl Viro static unsigned set_root_rcu(struct nameidata *nd) 79631e6b01fSNick Piggin { 79731e6b01fSNick Piggin struct fs_struct *fs = current->fs; 7988f47a016SAl Viro unsigned seq; 799c28cc364SNick Piggin 800c28cc364SNick Piggin do { 801c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 80231e6b01fSNick Piggin nd->root = fs->root; 8038f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 804c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 8058f47a016SAl Viro return nd->root_seq; 80631e6b01fSNick Piggin } 80731e6b01fSNick Piggin 8081d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 809051d3812SIan Kent { 810051d3812SIan Kent dput(path->dentry); 8114ac91378SJan Blunck if (path->mnt != nd->path.mnt) 812051d3812SIan Kent mntput(path->mnt); 813051d3812SIan Kent } 814051d3812SIan Kent 8157b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8167b9337aaSNick Piggin struct nameidata *nd) 817051d3812SIan Kent { 81831e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8194ac91378SJan Blunck dput(nd->path.dentry); 82031e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8214ac91378SJan Blunck mntput(nd->path.mnt); 8229a229683SHuang Shijie } 82331e6b01fSNick Piggin nd->path.mnt = path->mnt; 8244ac91378SJan Blunck nd->path.dentry = path->dentry; 825051d3812SIan Kent } 826051d3812SIan Kent 827b5fb63c1SChristoph Hellwig /* 828b5fb63c1SChristoph Hellwig * Helper to directly jump to a known parsed path from ->follow_link, 829b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 830b5fb63c1SChristoph Hellwig */ 8316e77137bSAl Viro void nd_jump_link(struct path *path) 832b5fb63c1SChristoph Hellwig { 8336e77137bSAl Viro struct nameidata *nd = current->nameidata; 834b5fb63c1SChristoph Hellwig path_put(&nd->path); 835b5fb63c1SChristoph Hellwig 836b5fb63c1SChristoph Hellwig nd->path = *path; 837b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 838b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 839b5fb63c1SChristoph Hellwig } 840b5fb63c1SChristoph Hellwig 841b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 842574197e0SAl Viro { 84321c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 844237d8b32SAl Viro struct inode *inode = last->inode; 845b9ff4429SAl Viro if (last->cookie && inode->i_op->put_link) 8465f2c4179SAl Viro inode->i_op->put_link(inode, last->cookie); 8476548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 848b9ff4429SAl Viro path_put(&last->link); 849574197e0SAl Viro } 850574197e0SAl Viro 851561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 852561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 853800179c9SKees Cook 854800179c9SKees Cook /** 855800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 85655852635SRandy Dunlap * @nd: nameidata pathwalk data 857800179c9SKees Cook * 858800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 859800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 860800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 861800179c9SKees Cook * processes from failing races against path names that may change out 862800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 863800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 864800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 865800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 866800179c9SKees Cook * 867800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 868800179c9SKees Cook */ 869fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 870800179c9SKees Cook { 871800179c9SKees Cook const struct inode *inode; 872800179c9SKees Cook const struct inode *parent; 873800179c9SKees Cook 874800179c9SKees Cook if (!sysctl_protected_symlinks) 875800179c9SKees Cook return 0; 876800179c9SKees Cook 877800179c9SKees Cook /* Allowed if owner and follower match. */ 878237d8b32SAl Viro inode = nd->stack[0].inode; 87981abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 880800179c9SKees Cook return 0; 881800179c9SKees Cook 882800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 883800179c9SKees Cook parent = nd->path.dentry->d_inode; 884800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 885800179c9SKees Cook return 0; 886800179c9SKees Cook 887800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 88881abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 889800179c9SKees Cook return 0; 890800179c9SKees Cook 89131956502SAl Viro if (nd->flags & LOOKUP_RCU) 89231956502SAl Viro return -ECHILD; 89331956502SAl Viro 8941cf2665bSAl Viro audit_log_link_denied("follow_link", &nd->stack[0].link); 895800179c9SKees Cook return -EACCES; 896800179c9SKees Cook } 897800179c9SKees Cook 898800179c9SKees Cook /** 899800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 900800179c9SKees Cook * @inode: the source inode to hardlink from 901800179c9SKees Cook * 902800179c9SKees Cook * Return false if at least one of the following conditions: 903800179c9SKees Cook * - inode is not a regular file 904800179c9SKees Cook * - inode is setuid 905800179c9SKees Cook * - inode is setgid and group-exec 906800179c9SKees Cook * - access failure for read and write 907800179c9SKees Cook * 908800179c9SKees Cook * Otherwise returns true. 909800179c9SKees Cook */ 910800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 911800179c9SKees Cook { 912800179c9SKees Cook umode_t mode = inode->i_mode; 913800179c9SKees Cook 914800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 915800179c9SKees Cook if (!S_ISREG(mode)) 916800179c9SKees Cook return false; 917800179c9SKees Cook 918800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 919800179c9SKees Cook if (mode & S_ISUID) 920800179c9SKees Cook return false; 921800179c9SKees Cook 922800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 923800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 924800179c9SKees Cook return false; 925800179c9SKees Cook 926800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 927800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 928800179c9SKees Cook return false; 929800179c9SKees Cook 930800179c9SKees Cook return true; 931800179c9SKees Cook } 932800179c9SKees Cook 933800179c9SKees Cook /** 934800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 935800179c9SKees Cook * @link: the source to hardlink from 936800179c9SKees Cook * 937800179c9SKees Cook * Block hardlink when all of: 938800179c9SKees Cook * - sysctl_protected_hardlinks enabled 939800179c9SKees Cook * - fsuid does not match inode 940800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 941800179c9SKees Cook * - not CAP_FOWNER 942800179c9SKees Cook * 943800179c9SKees Cook * Returns 0 if successful, -ve on error. 944800179c9SKees Cook */ 945800179c9SKees Cook static int may_linkat(struct path *link) 946800179c9SKees Cook { 947800179c9SKees Cook const struct cred *cred; 948800179c9SKees Cook struct inode *inode; 949800179c9SKees Cook 950800179c9SKees Cook if (!sysctl_protected_hardlinks) 951800179c9SKees Cook return 0; 952800179c9SKees Cook 953800179c9SKees Cook cred = current_cred(); 954800179c9SKees Cook inode = link->dentry->d_inode; 955800179c9SKees Cook 956800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 957800179c9SKees Cook * otherwise, it must be a safe source. 958800179c9SKees Cook */ 95981abe27bSEric W. Biederman if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || 960800179c9SKees Cook capable(CAP_FOWNER)) 961800179c9SKees Cook return 0; 962800179c9SKees Cook 963a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 964800179c9SKees Cook return -EPERM; 965800179c9SKees Cook } 966800179c9SKees Cook 9673b2e7f75SAl Viro static __always_inline 9683b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 9691da177e4SLinus Torvalds { 970ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 9711cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 972237d8b32SAl Viro struct inode *inode = last->inode; 9736d7b5aaeSAl Viro int error; 9740a959df5SAl Viro const char *res; 9751da177e4SLinus Torvalds 9768fa9dd24SNeilBrown if (!(nd->flags & LOOKUP_RCU)) { 9778fa9dd24SNeilBrown touch_atime(&last->link); 9788fa9dd24SNeilBrown cond_resched(); 9798fa9dd24SNeilBrown } else if (atime_needs_update(&last->link, inode)) { 9808fa9dd24SNeilBrown if (unlikely(unlazy_walk(nd, NULL, 0))) 9818fa9dd24SNeilBrown return ERR_PTR(-ECHILD); 9828fa9dd24SNeilBrown touch_atime(&last->link); 9838fa9dd24SNeilBrown } 9848fa9dd24SNeilBrown 985bda0be7aSNeilBrown error = security_inode_follow_link(dentry, inode, 986bda0be7aSNeilBrown nd->flags & LOOKUP_RCU); 987bda0be7aSNeilBrown if (unlikely(error)) 9886920a440SAl Viro return ERR_PTR(error); 98936f3b4f6SAl Viro 99086acdca1SAl Viro nd->last_type = LAST_BIND; 991d4dee48bSAl Viro res = inode->i_link; 992d4dee48bSAl Viro if (!res) { 9938c1b4566SAl Viro if (nd->flags & LOOKUP_RCU) { 9948c1b4566SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 9958c1b4566SAl Viro return ERR_PTR(-ECHILD); 9968c1b4566SAl Viro } 9976e77137bSAl Viro res = inode->i_op->follow_link(dentry, &last->cookie); 998fab51e8aSAl Viro if (IS_ERR_OR_NULL(res)) { 9996920a440SAl Viro last->cookie = NULL; 1000fab51e8aSAl Viro return res; 10010a959df5SAl Viro } 1002fab51e8aSAl Viro } 1003fab51e8aSAl Viro if (*res == '/') { 10048c1b4566SAl Viro if (nd->flags & LOOKUP_RCU) { 10058f47a016SAl Viro struct dentry *d; 10068f47a016SAl Viro if (!nd->root.mnt) 10078f47a016SAl Viro set_root_rcu(nd); 10088f47a016SAl Viro nd->path = nd->root; 10098f47a016SAl Viro d = nd->path.dentry; 10108f47a016SAl Viro nd->inode = d->d_inode; 10118f47a016SAl Viro nd->seq = nd->root_seq; 10128f47a016SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 10138c1b4566SAl Viro return ERR_PTR(-ECHILD); 10148f47a016SAl Viro } else { 1015fab51e8aSAl Viro if (!nd->root.mnt) 1016fab51e8aSAl Viro set_root(nd); 1017fab51e8aSAl Viro path_put(&nd->path); 1018fab51e8aSAl Viro nd->path = nd->root; 1019fab51e8aSAl Viro path_get(&nd->root); 1020fab51e8aSAl Viro nd->inode = nd->path.dentry->d_inode; 10218f47a016SAl Viro } 1022fab51e8aSAl Viro nd->flags |= LOOKUP_JUMPED; 1023fab51e8aSAl Viro while (unlikely(*++res == '/')) 1024fab51e8aSAl Viro ; 1025fab51e8aSAl Viro } 1026fab51e8aSAl Viro if (!*res) 1027fab51e8aSAl Viro res = NULL; 10280a959df5SAl Viro return res; 10290a959df5SAl Viro } 10306d7b5aaeSAl Viro 1031f015f126SDavid Howells /* 1032f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1033f015f126SDavid Howells * 1034f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1035f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1036f015f126SDavid Howells * Up is towards /. 1037f015f126SDavid Howells * 1038f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1039f015f126SDavid Howells * root. 1040f015f126SDavid Howells */ 1041bab77ebfSAl Viro int follow_up(struct path *path) 10421da177e4SLinus Torvalds { 10430714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 10440714a533SAl Viro struct mount *parent; 10451da177e4SLinus Torvalds struct dentry *mountpoint; 104699b7db7bSNick Piggin 104748a066e7SAl Viro read_seqlock_excl(&mount_lock); 10480714a533SAl Viro parent = mnt->mnt_parent; 10493c0a6163SAl Viro if (parent == mnt) { 105048a066e7SAl Viro read_sequnlock_excl(&mount_lock); 10511da177e4SLinus Torvalds return 0; 10521da177e4SLinus Torvalds } 10530714a533SAl Viro mntget(&parent->mnt); 1054a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 105548a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1056bab77ebfSAl Viro dput(path->dentry); 1057bab77ebfSAl Viro path->dentry = mountpoint; 1058bab77ebfSAl Viro mntput(path->mnt); 10590714a533SAl Viro path->mnt = &parent->mnt; 10601da177e4SLinus Torvalds return 1; 10611da177e4SLinus Torvalds } 10624d359507SAl Viro EXPORT_SYMBOL(follow_up); 10631da177e4SLinus Torvalds 1064b5c84bf6SNick Piggin /* 10659875cf80SDavid Howells * Perform an automount 10669875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 10679875cf80SDavid Howells * were called with. 10681da177e4SLinus Torvalds */ 1069756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 10709875cf80SDavid Howells bool *need_mntput) 107131e6b01fSNick Piggin { 10729875cf80SDavid Howells struct vfsmount *mnt; 1073ea5b778aSDavid Howells int err; 10749875cf80SDavid Howells 10759875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 10769875cf80SDavid Howells return -EREMOTE; 10779875cf80SDavid Howells 10780ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 10790ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 10800ec26fd0SMiklos Szeredi * the name. 10810ec26fd0SMiklos Szeredi * 10820ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 10835a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 10840ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 10850ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 10860ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 10870ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 10885a30d8a2SDavid Howells */ 1089756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 1090d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 10915a30d8a2SDavid Howells path->dentry->d_inode) 10929875cf80SDavid Howells return -EISDIR; 10930ec26fd0SMiklos Szeredi 1094756daf26SNeilBrown nd->total_link_count++; 1095756daf26SNeilBrown if (nd->total_link_count >= 40) 10969875cf80SDavid Howells return -ELOOP; 10979875cf80SDavid Howells 10989875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 10999875cf80SDavid Howells if (IS_ERR(mnt)) { 11009875cf80SDavid Howells /* 11019875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 11029875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 11039875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 11049875cf80SDavid Howells * 11059875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 11069875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 11079875cf80SDavid Howells * the path is inaccessible and we should say so. 11089875cf80SDavid Howells */ 1109756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 11109875cf80SDavid Howells return -EREMOTE; 11119875cf80SDavid Howells return PTR_ERR(mnt); 111231e6b01fSNick Piggin } 1113ea5b778aSDavid Howells 11149875cf80SDavid Howells if (!mnt) /* mount collision */ 11159875cf80SDavid Howells return 0; 11169875cf80SDavid Howells 11178aef1884SAl Viro if (!*need_mntput) { 11188aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 11198aef1884SAl Viro mntget(path->mnt); 11208aef1884SAl Viro *need_mntput = true; 11218aef1884SAl Viro } 112219a167afSAl Viro err = finish_automount(mnt, path); 1123ea5b778aSDavid Howells 1124ea5b778aSDavid Howells switch (err) { 1125ea5b778aSDavid Howells case -EBUSY: 1126ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 112719a167afSAl Viro return 0; 1128ea5b778aSDavid Howells case 0: 11298aef1884SAl Viro path_put(path); 11309875cf80SDavid Howells path->mnt = mnt; 11319875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 11329875cf80SDavid Howells return 0; 113319a167afSAl Viro default: 113419a167afSAl Viro return err; 11359875cf80SDavid Howells } 113619a167afSAl Viro 1137ea5b778aSDavid Howells } 11389875cf80SDavid Howells 11399875cf80SDavid Howells /* 11409875cf80SDavid Howells * Handle a dentry that is managed in some way. 1141cc53ce53SDavid Howells * - Flagged for transit management (autofs) 11429875cf80SDavid Howells * - Flagged as mountpoint 11439875cf80SDavid Howells * - Flagged as automount point 11449875cf80SDavid Howells * 11459875cf80SDavid Howells * This may only be called in refwalk mode. 11469875cf80SDavid Howells * 11479875cf80SDavid Howells * Serialization is taken care of in namespace.c 11489875cf80SDavid Howells */ 1149756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 11509875cf80SDavid Howells { 11518aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 11529875cf80SDavid Howells unsigned managed; 11539875cf80SDavid Howells bool need_mntput = false; 11548aef1884SAl Viro int ret = 0; 11559875cf80SDavid Howells 11569875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 11579875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 11589875cf80SDavid Howells * the components of that value change under us */ 11599875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 11609875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 11619875cf80SDavid Howells unlikely(managed != 0)) { 1162cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1163cc53ce53SDavid Howells * being held. */ 1164cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1165cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1166cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 11671aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1168cc53ce53SDavid Howells if (ret < 0) 11698aef1884SAl Viro break; 1170cc53ce53SDavid Howells } 1171cc53ce53SDavid Howells 11729875cf80SDavid Howells /* Transit to a mounted filesystem. */ 11739875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 11749875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 11759875cf80SDavid Howells if (mounted) { 11769875cf80SDavid Howells dput(path->dentry); 11779875cf80SDavid Howells if (need_mntput) 1178463ffb2eSAl Viro mntput(path->mnt); 1179463ffb2eSAl Viro path->mnt = mounted; 1180463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 11819875cf80SDavid Howells need_mntput = true; 11829875cf80SDavid Howells continue; 1183463ffb2eSAl Viro } 1184463ffb2eSAl Viro 11859875cf80SDavid Howells /* Something is mounted on this dentry in another 11869875cf80SDavid Howells * namespace and/or whatever was mounted there in this 118748a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 118848a066e7SAl Viro * get it */ 11891da177e4SLinus Torvalds } 11909875cf80SDavid Howells 11919875cf80SDavid Howells /* Handle an automount point */ 11929875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1193756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 11949875cf80SDavid Howells if (ret < 0) 11958aef1884SAl Viro break; 11969875cf80SDavid Howells continue; 11979875cf80SDavid Howells } 11989875cf80SDavid Howells 11999875cf80SDavid Howells /* We didn't change the current path point */ 12009875cf80SDavid Howells break; 12019875cf80SDavid Howells } 12028aef1884SAl Viro 12038aef1884SAl Viro if (need_mntput && path->mnt == mnt) 12048aef1884SAl Viro mntput(path->mnt); 12058aef1884SAl Viro if (ret == -EISDIR) 12068aef1884SAl Viro ret = 0; 12078402752eSAl Viro if (need_mntput) 12088402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 12098402752eSAl Viro if (unlikely(ret < 0)) 12108402752eSAl Viro path_put_conditional(path, nd); 12118402752eSAl Viro return ret; 12121da177e4SLinus Torvalds } 12131da177e4SLinus Torvalds 1214cc53ce53SDavid Howells int follow_down_one(struct path *path) 12151da177e4SLinus Torvalds { 12161da177e4SLinus Torvalds struct vfsmount *mounted; 12171da177e4SLinus Torvalds 12181c755af4SAl Viro mounted = lookup_mnt(path); 12191da177e4SLinus Torvalds if (mounted) { 12209393bd07SAl Viro dput(path->dentry); 12219393bd07SAl Viro mntput(path->mnt); 12229393bd07SAl Viro path->mnt = mounted; 12239393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12241da177e4SLinus Torvalds return 1; 12251da177e4SLinus Torvalds } 12261da177e4SLinus Torvalds return 0; 12271da177e4SLinus Torvalds } 12284d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12291da177e4SLinus Torvalds 1230b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 123162a7375eSIan Kent { 1232b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1233b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 123462a7375eSIan Kent } 123562a7375eSIan Kent 12369875cf80SDavid Howells /* 1237287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1238287548e4SAl Viro * we meet a managed dentry that would need blocking. 12399875cf80SDavid Howells */ 12409875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1241254cf582SAl Viro struct inode **inode, unsigned *seqp) 12429875cf80SDavid Howells { 124362a7375eSIan Kent for (;;) { 1244c7105365SAl Viro struct mount *mounted; 124562a7375eSIan Kent /* 124662a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 124762a7375eSIan Kent * that wants to block transit. 124862a7375eSIan Kent */ 1249b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1250b8faf035SNeilBrown case -ECHILD: 1251b8faf035SNeilBrown default: 1252ab90911fSDavid Howells return false; 1253b8faf035SNeilBrown case -EISDIR: 1254b8faf035SNeilBrown return true; 1255b8faf035SNeilBrown case 0: 1256b8faf035SNeilBrown break; 1257b8faf035SNeilBrown } 125862a7375eSIan Kent 125962a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1260b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 126162a7375eSIan Kent 1262474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 12639875cf80SDavid Howells if (!mounted) 12649875cf80SDavid Howells break; 1265c7105365SAl Viro path->mnt = &mounted->mnt; 1266c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1267a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1268254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 126959430262SLinus Torvalds /* 127059430262SLinus Torvalds * Update the inode too. We don't need to re-check the 127159430262SLinus Torvalds * dentry sequence number here after this d_inode read, 127259430262SLinus Torvalds * because a mount-point is always pinned. 127359430262SLinus Torvalds */ 127459430262SLinus Torvalds *inode = path->dentry->d_inode; 12759875cf80SDavid Howells } 1276f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1277b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1278287548e4SAl Viro } 1279287548e4SAl Viro 128031e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 128131e6b01fSNick Piggin { 12824023bfc9SAl Viro struct inode *inode = nd->inode; 12837bd88377SAl Viro if (!nd->root.mnt) 128431e6b01fSNick Piggin set_root_rcu(nd); 128531e6b01fSNick Piggin 128631e6b01fSNick Piggin while (1) { 1287aed434adSAl Viro if (path_equal(&nd->path, &nd->root)) 128831e6b01fSNick Piggin break; 128931e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 129031e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 129131e6b01fSNick Piggin struct dentry *parent = old->d_parent; 129231e6b01fSNick Piggin unsigned seq; 129331e6b01fSNick Piggin 12944023bfc9SAl Viro inode = parent->d_inode; 129531e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 1296aed434adSAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 1297aed434adSAl Viro return -ECHILD; 129831e6b01fSNick Piggin nd->path.dentry = parent; 129931e6b01fSNick Piggin nd->seq = seq; 130031e6b01fSNick Piggin break; 1301aed434adSAl Viro } else { 1302aed434adSAl Viro struct mount *mnt = real_mount(nd->path.mnt); 1303aed434adSAl Viro struct mount *mparent = mnt->mnt_parent; 1304aed434adSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1305aed434adSAl Viro struct inode *inode2 = mountpoint->d_inode; 1306aed434adSAl Viro unsigned seq = read_seqcount_begin(&mountpoint->d_seq); 1307aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1308aed434adSAl Viro return -ECHILD; 1309aed434adSAl Viro if (&mparent->mnt == nd->path.mnt) 131031e6b01fSNick Piggin break; 1311aed434adSAl Viro /* we know that mountpoint was pinned */ 1312aed434adSAl Viro nd->path.dentry = mountpoint; 1313aed434adSAl Viro nd->path.mnt = &mparent->mnt; 1314aed434adSAl Viro inode = inode2; 1315aed434adSAl Viro nd->seq = seq; 131631e6b01fSNick Piggin } 1317aed434adSAl Viro } 1318aed434adSAl Viro while (unlikely(d_mountpoint(nd->path.dentry))) { 1319b37199e6SAl Viro struct mount *mounted; 1320b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1321aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1322aed434adSAl Viro return -ECHILD; 1323b37199e6SAl Viro if (!mounted) 1324b37199e6SAl Viro break; 1325b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1326b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 13274023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1328b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1329b37199e6SAl Viro } 13304023bfc9SAl Viro nd->inode = inode; 133131e6b01fSNick Piggin return 0; 133231e6b01fSNick Piggin } 133331e6b01fSNick Piggin 13349875cf80SDavid Howells /* 1335cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1336cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1337cc53ce53SDavid Howells * caller is permitted to proceed or not. 1338cc53ce53SDavid Howells */ 13397cc90cc3SAl Viro int follow_down(struct path *path) 1340cc53ce53SDavid Howells { 1341cc53ce53SDavid Howells unsigned managed; 1342cc53ce53SDavid Howells int ret; 1343cc53ce53SDavid Howells 1344cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1345cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1346cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1347cc53ce53SDavid Howells * being held. 1348cc53ce53SDavid Howells * 1349cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1350cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1351cc53ce53SDavid Howells * other than its daemon the right to mount on its 1352cc53ce53SDavid Howells * superstructure. 1353cc53ce53SDavid Howells * 1354cc53ce53SDavid Howells * The filesystem may sleep at this point. 1355cc53ce53SDavid Howells */ 1356cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1357cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1358cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1359ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 13601aed3e42SAl Viro path->dentry, false); 1361cc53ce53SDavid Howells if (ret < 0) 1362cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1363cc53ce53SDavid Howells } 1364cc53ce53SDavid Howells 1365cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1366cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1367cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1368cc53ce53SDavid Howells if (!mounted) 1369cc53ce53SDavid Howells break; 1370cc53ce53SDavid Howells dput(path->dentry); 1371cc53ce53SDavid Howells mntput(path->mnt); 1372cc53ce53SDavid Howells path->mnt = mounted; 1373cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1374cc53ce53SDavid Howells continue; 1375cc53ce53SDavid Howells } 1376cc53ce53SDavid Howells 1377cc53ce53SDavid Howells /* Don't handle automount points here */ 1378cc53ce53SDavid Howells break; 1379cc53ce53SDavid Howells } 1380cc53ce53SDavid Howells return 0; 1381cc53ce53SDavid Howells } 13824d359507SAl Viro EXPORT_SYMBOL(follow_down); 1383cc53ce53SDavid Howells 1384cc53ce53SDavid Howells /* 13859875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 13869875cf80SDavid Howells */ 13879875cf80SDavid Howells static void follow_mount(struct path *path) 13889875cf80SDavid Howells { 13899875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 13909875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 13919875cf80SDavid Howells if (!mounted) 13929875cf80SDavid Howells break; 13939875cf80SDavid Howells dput(path->dentry); 13949875cf80SDavid Howells mntput(path->mnt); 13959875cf80SDavid Howells path->mnt = mounted; 13969875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 13979875cf80SDavid Howells } 13989875cf80SDavid Howells } 13999875cf80SDavid Howells 140031e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 14011da177e4SLinus Torvalds { 14027bd88377SAl Viro if (!nd->root.mnt) 14032a737871SAl Viro set_root(nd); 1404e518ddb7SAndreas Mohr 14051da177e4SLinus Torvalds while(1) { 14064ac91378SJan Blunck struct dentry *old = nd->path.dentry; 14071da177e4SLinus Torvalds 14082a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 14092a737871SAl Viro nd->path.mnt == nd->root.mnt) { 14101da177e4SLinus Torvalds break; 14111da177e4SLinus Torvalds } 14124ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 14133088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 14143088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 14151da177e4SLinus Torvalds dput(old); 14161da177e4SLinus Torvalds break; 14171da177e4SLinus Torvalds } 14183088dd70SAl Viro if (!follow_up(&nd->path)) 14191da177e4SLinus Torvalds break; 14201da177e4SLinus Torvalds } 142179ed0226SAl Viro follow_mount(&nd->path); 142231e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 14231da177e4SLinus Torvalds } 14241da177e4SLinus Torvalds 14251da177e4SLinus Torvalds /* 1426bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1427bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1428bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1429bad61189SMiklos Szeredi * 1430bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1431baa03890SNick Piggin */ 1432bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1433201f956eSAl Viro unsigned int flags, bool *need_lookup) 1434baa03890SNick Piggin { 1435baa03890SNick Piggin struct dentry *dentry; 1436bad61189SMiklos Szeredi int error; 1437baa03890SNick Piggin 1438bad61189SMiklos Szeredi *need_lookup = false; 1439bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1440bad61189SMiklos Szeredi if (dentry) { 144139e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1442201f956eSAl Viro error = d_revalidate(dentry, flags); 1443bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1444bad61189SMiklos Szeredi if (error < 0) { 1445bad61189SMiklos Szeredi dput(dentry); 1446bad61189SMiklos Szeredi return ERR_PTR(error); 14475542aa2fSEric W. Biederman } else { 14485542aa2fSEric W. Biederman d_invalidate(dentry); 1449bad61189SMiklos Szeredi dput(dentry); 1450bad61189SMiklos Szeredi dentry = NULL; 1451bad61189SMiklos Szeredi } 1452bad61189SMiklos Szeredi } 1453bad61189SMiklos Szeredi } 1454bad61189SMiklos Szeredi } 1455baa03890SNick Piggin 1456bad61189SMiklos Szeredi if (!dentry) { 1457bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1458baa03890SNick Piggin if (unlikely(!dentry)) 1459baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1460baa03890SNick Piggin 1461bad61189SMiklos Szeredi *need_lookup = true; 1462baa03890SNick Piggin } 1463baa03890SNick Piggin return dentry; 1464baa03890SNick Piggin } 1465baa03890SNick Piggin 1466baa03890SNick Piggin /* 146713a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 146813a2c3beSJ. Bruce Fields * unhashed. 1469bad61189SMiklos Szeredi * 1470bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 147144396f4bSJosef Bacik */ 1472bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 147372bd866aSAl Viro unsigned int flags) 147444396f4bSJosef Bacik { 147544396f4bSJosef Bacik struct dentry *old; 147644396f4bSJosef Bacik 147744396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1478bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1479e188dc02SMiklos Szeredi dput(dentry); 148044396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1481e188dc02SMiklos Szeredi } 148244396f4bSJosef Bacik 148372bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 148444396f4bSJosef Bacik if (unlikely(old)) { 148544396f4bSJosef Bacik dput(dentry); 148644396f4bSJosef Bacik dentry = old; 148744396f4bSJosef Bacik } 148844396f4bSJosef Bacik return dentry; 148944396f4bSJosef Bacik } 149044396f4bSJosef Bacik 1491a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 149272bd866aSAl Viro struct dentry *base, unsigned int flags) 1493a3255546SAl Viro { 1494bad61189SMiklos Szeredi bool need_lookup; 1495a3255546SAl Viro struct dentry *dentry; 1496a3255546SAl Viro 149772bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1498bad61189SMiklos Szeredi if (!need_lookup) 1499a3255546SAl Viro return dentry; 1500bad61189SMiklos Szeredi 150172bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1502a3255546SAl Viro } 1503a3255546SAl Viro 150444396f4bSJosef Bacik /* 15051da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 15061da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 15071da177e4SLinus Torvalds * It _is_ time-critical. 15081da177e4SLinus Torvalds */ 1509e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 1510254cf582SAl Viro struct path *path, struct inode **inode, 1511254cf582SAl Viro unsigned *seqp) 15121da177e4SLinus Torvalds { 15134ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 151431e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 15155a18fff2SAl Viro int need_reval = 1; 15165a18fff2SAl Viro int status = 1; 15179875cf80SDavid Howells int err; 15189875cf80SDavid Howells 15193cac260aSAl Viro /* 1520b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1521b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1522b04f784eSNick Piggin * do the non-racy lookup, below. 1523b04f784eSNick Piggin */ 152431e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 152531e6b01fSNick Piggin unsigned seq; 1526766c4cbfSAl Viro bool negative; 1527da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15285a18fff2SAl Viro if (!dentry) 15295a18fff2SAl Viro goto unlazy; 15305a18fff2SAl Viro 153112f8ad4bSLinus Torvalds /* 153212f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 153312f8ad4bSLinus Torvalds * the dentry name information from lookup. 153412f8ad4bSLinus Torvalds */ 153563afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1536766c4cbfSAl Viro negative = d_is_negative(dentry); 153712f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 153812f8ad4bSLinus Torvalds return -ECHILD; 1539766c4cbfSAl Viro if (negative) 1540766c4cbfSAl Viro return -ENOENT; 154112f8ad4bSLinus Torvalds 154212f8ad4bSLinus Torvalds /* 154312f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 154412f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 154512f8ad4bSLinus Torvalds * 154612f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 154712f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 154812f8ad4bSLinus Torvalds */ 154931e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 155031e6b01fSNick Piggin return -ECHILD; 15515a18fff2SAl Viro 1552254cf582SAl Viro *seqp = seq; 155324643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 15544ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15555a18fff2SAl Viro if (unlikely(status <= 0)) { 15565a18fff2SAl Viro if (status != -ECHILD) 15575a18fff2SAl Viro need_reval = 0; 15585a18fff2SAl Viro goto unlazy; 15595a18fff2SAl Viro } 156024643087SAl Viro } 156131e6b01fSNick Piggin path->mnt = mnt; 156231e6b01fSNick Piggin path->dentry = dentry; 1563254cf582SAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 15649875cf80SDavid Howells return 0; 15655a18fff2SAl Viro unlazy: 1566254cf582SAl Viro if (unlazy_walk(nd, dentry, seq)) 15675a18fff2SAl Viro return -ECHILD; 15685a18fff2SAl Viro } else { 1569e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 157024643087SAl Viro } 15715a18fff2SAl Viro 157281e6f520SAl Viro if (unlikely(!dentry)) 157381e6f520SAl Viro goto need_lookup; 15745a18fff2SAl Viro 15755a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 15764ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15775a18fff2SAl Viro if (unlikely(status <= 0)) { 15785a18fff2SAl Viro if (status < 0) { 15795a18fff2SAl Viro dput(dentry); 15805a18fff2SAl Viro return status; 15815a18fff2SAl Viro } 15825542aa2fSEric W. Biederman d_invalidate(dentry); 15835a18fff2SAl Viro dput(dentry); 158481e6f520SAl Viro goto need_lookup; 15855a18fff2SAl Viro } 1586697f514dSMiklos Szeredi 1587766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1588766c4cbfSAl Viro dput(dentry); 1589766c4cbfSAl Viro return -ENOENT; 1590766c4cbfSAl Viro } 15911da177e4SLinus Torvalds path->mnt = mnt; 15921da177e4SLinus Torvalds path->dentry = dentry; 1593756daf26SNeilBrown err = follow_managed(path, nd); 15948402752eSAl Viro if (likely(!err)) 159563afdfc7SDavid Howells *inode = d_backing_inode(path->dentry); 15968402752eSAl Viro return err; 159781e6f520SAl Viro 159881e6f520SAl Viro need_lookup: 1599697f514dSMiklos Szeredi return 1; 1600697f514dSMiklos Szeredi } 1601697f514dSMiklos Szeredi 1602697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1603cc2a5271SAl Viro static int lookup_slow(struct nameidata *nd, struct path *path) 1604697f514dSMiklos Szeredi { 1605697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1606697f514dSMiklos Szeredi 1607697f514dSMiklos Szeredi parent = nd->path.dentry; 160881e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 160981e6f520SAl Viro 161081e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 1611cc2a5271SAl Viro dentry = __lookup_hash(&nd->last, parent, nd->flags); 161281e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 161381e6f520SAl Viro if (IS_ERR(dentry)) 161481e6f520SAl Viro return PTR_ERR(dentry); 1615697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1616697f514dSMiklos Szeredi path->dentry = dentry; 16178402752eSAl Viro return follow_managed(path, nd); 16181da177e4SLinus Torvalds } 16191da177e4SLinus Torvalds 162052094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 162152094c8aSAl Viro { 162252094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16234ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 162452094c8aSAl Viro if (err != -ECHILD) 162552094c8aSAl Viro return err; 16266e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 162752094c8aSAl Viro return -ECHILD; 162852094c8aSAl Viro } 16294ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 163052094c8aSAl Viro } 163152094c8aSAl Viro 16329856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 16339856fa1bSAl Viro { 16349856fa1bSAl Viro if (type == LAST_DOTDOT) { 16359856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 163670291aecSAl Viro return follow_dotdot_rcu(nd); 16379856fa1bSAl Viro } else 16389856fa1bSAl Viro follow_dotdot(nd); 16399856fa1bSAl Viro } 16409856fa1bSAl Viro return 0; 16419856fa1bSAl Viro } 16429856fa1bSAl Viro 1643181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1644181548c0SAl Viro struct inode *inode, unsigned seq) 1645d63ff28fSAl Viro { 1646626de996SAl Viro int error; 16471cf2665bSAl Viro struct saved *last; 1648756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1649626de996SAl Viro path_to_nameidata(link, nd); 1650626de996SAl Viro return -ELOOP; 1651626de996SAl Viro } 1652bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1653cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1654cd179f44SAl Viro mntget(link->mnt); 16557973387aSAl Viro } 1656626de996SAl Viro error = nd_alloc_stack(nd); 1657626de996SAl Viro if (unlikely(error)) { 1658bc40aee0SAl Viro if (error == -ECHILD) { 1659bc40aee0SAl Viro if (unlikely(unlazy_link(nd, link, seq))) 1660bc40aee0SAl Viro return -ECHILD; 1661bc40aee0SAl Viro error = nd_alloc_stack(nd); 1662bc40aee0SAl Viro } 1663bc40aee0SAl Viro if (error) { 1664cd179f44SAl Viro path_put(link); 1665626de996SAl Viro return error; 1666626de996SAl Viro } 1667bc40aee0SAl Viro } 1668626de996SAl Viro 1669ab104923SAl Viro last = nd->stack + nd->depth++; 16701cf2665bSAl Viro last->link = *link; 1671ab104923SAl Viro last->cookie = NULL; 1672181548c0SAl Viro last->inode = inode; 16730450b2d1SAl Viro last->seq = seq; 1674d63ff28fSAl Viro return 1; 1675d63ff28fSAl Viro } 1676d63ff28fSAl Viro 16773ddcd056SLinus Torvalds /* 16783ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 16793ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 16803ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 16813ddcd056SLinus Torvalds * for the common case. 16823ddcd056SLinus Torvalds */ 1683254cf582SAl Viro static inline int should_follow_link(struct nameidata *nd, struct path *link, 1684181548c0SAl Viro int follow, 1685181548c0SAl Viro struct inode *inode, unsigned seq) 16863ddcd056SLinus Torvalds { 1687d63ff28fSAl Viro if (likely(!d_is_symlink(link->dentry))) 1688d63ff28fSAl Viro return 0; 1689d63ff28fSAl Viro if (!follow) 1690d63ff28fSAl Viro return 0; 1691181548c0SAl Viro return pick_link(nd, link, inode, seq); 16923ddcd056SLinus Torvalds } 16933ddcd056SLinus Torvalds 16944693a547SAl Viro enum {WALK_GET = 1, WALK_PUT = 2}; 16954693a547SAl Viro 16964693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1697ce57dfc1SAl Viro { 1698caa85634SAl Viro struct path path; 1699ce57dfc1SAl Viro struct inode *inode; 1700254cf582SAl Viro unsigned seq; 1701ce57dfc1SAl Viro int err; 1702ce57dfc1SAl Viro /* 1703ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1704ce57dfc1SAl Viro * to be able to know about the current root directory and 1705ce57dfc1SAl Viro * parent relationships. 1706ce57dfc1SAl Viro */ 17074693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 17084693a547SAl Viro err = handle_dots(nd, nd->last_type); 17094693a547SAl Viro if (flags & WALK_PUT) 17104693a547SAl Viro put_link(nd); 17114693a547SAl Viro return err; 17124693a547SAl Viro } 1713254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1714ce57dfc1SAl Viro if (unlikely(err)) { 1715697f514dSMiklos Szeredi if (err < 0) 1716f0a9ba70SAl Viro return err; 1717697f514dSMiklos Szeredi 1718caa85634SAl Viro err = lookup_slow(nd, &path); 1719697f514dSMiklos Szeredi if (err < 0) 1720f0a9ba70SAl Viro return err; 1721697f514dSMiklos Szeredi 172263afdfc7SDavid Howells inode = d_backing_inode(path.dentry); 1723254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1724697f514dSMiklos Szeredi err = -ENOENT; 1725caa85634SAl Viro if (d_is_negative(path.dentry)) 1726697f514dSMiklos Szeredi goto out_path_put; 1727766c4cbfSAl Viro } 1728697f514dSMiklos Szeredi 17294693a547SAl Viro if (flags & WALK_PUT) 17304693a547SAl Viro put_link(nd); 1731181548c0SAl Viro err = should_follow_link(nd, &path, flags & WALK_GET, inode, seq); 1732d63ff28fSAl Viro if (unlikely(err)) 1733d63ff28fSAl Viro return err; 1734caa85634SAl Viro path_to_nameidata(&path, nd); 1735ce57dfc1SAl Viro nd->inode = inode; 1736254cf582SAl Viro nd->seq = seq; 1737ce57dfc1SAl Viro return 0; 1738697f514dSMiklos Szeredi 1739697f514dSMiklos Szeredi out_path_put: 1740caa85634SAl Viro path_to_nameidata(&path, nd); 1741697f514dSMiklos Szeredi return err; 1742ce57dfc1SAl Viro } 1743ce57dfc1SAl Viro 17441da177e4SLinus Torvalds /* 1745bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1746bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1747bfcfaa77SLinus Torvalds * 1748bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1749bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1750bfcfaa77SLinus Torvalds * fast. 1751bfcfaa77SLinus Torvalds * 1752bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1753bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1754bfcfaa77SLinus Torvalds * crossing operation. 1755bfcfaa77SLinus Torvalds * 1756bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1757bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1758bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1759bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1760bfcfaa77SLinus Torvalds */ 1761bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1762bfcfaa77SLinus Torvalds 1763f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1764bfcfaa77SLinus Torvalds 1765f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1766bfcfaa77SLinus Torvalds 1767bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1768bfcfaa77SLinus Torvalds { 176999d263d4SLinus Torvalds return hash_64(hash, 32); 1770bfcfaa77SLinus Torvalds } 1771bfcfaa77SLinus Torvalds 1772bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1773bfcfaa77SLinus Torvalds 1774bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1775bfcfaa77SLinus Torvalds 1776bfcfaa77SLinus Torvalds #endif 1777bfcfaa77SLinus Torvalds 1778bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1779bfcfaa77SLinus Torvalds { 1780bfcfaa77SLinus Torvalds unsigned long a, mask; 1781bfcfaa77SLinus Torvalds unsigned long hash = 0; 1782bfcfaa77SLinus Torvalds 1783bfcfaa77SLinus Torvalds for (;;) { 1784e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1785bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1786bfcfaa77SLinus Torvalds break; 1787bfcfaa77SLinus Torvalds hash += a; 1788f132c5beSAl Viro hash *= 9; 1789bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1790bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1791bfcfaa77SLinus Torvalds if (!len) 1792bfcfaa77SLinus Torvalds goto done; 1793bfcfaa77SLinus Torvalds } 1794a5c21dceSWill Deacon mask = bytemask_from_count(len); 1795bfcfaa77SLinus Torvalds hash += mask & a; 1796bfcfaa77SLinus Torvalds done: 1797bfcfaa77SLinus Torvalds return fold_hash(hash); 1798bfcfaa77SLinus Torvalds } 1799bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1800bfcfaa77SLinus Torvalds 1801bfcfaa77SLinus Torvalds /* 1802bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1803d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1804bfcfaa77SLinus Torvalds */ 1805d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1806bfcfaa77SLinus Torvalds { 180736126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 180836126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1809bfcfaa77SLinus Torvalds 1810bfcfaa77SLinus Torvalds hash = a = 0; 1811bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1812bfcfaa77SLinus Torvalds do { 1813bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1814bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1815e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 181636126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 181736126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1818bfcfaa77SLinus Torvalds 181936126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 182036126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 182136126f8fSLinus Torvalds 182236126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 182336126f8fSLinus Torvalds 182436126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 18259226b5b4SLinus Torvalds len += find_zero(mask); 1826d6bb3e90SLinus Torvalds return hashlen_create(fold_hash(hash), len); 1827bfcfaa77SLinus Torvalds } 1828bfcfaa77SLinus Torvalds 1829bfcfaa77SLinus Torvalds #else 1830bfcfaa77SLinus Torvalds 18310145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 18320145acc2SLinus Torvalds { 18330145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 18340145acc2SLinus Torvalds while (len--) 18350145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 18360145acc2SLinus Torvalds return end_name_hash(hash); 18370145acc2SLinus Torvalds } 1838ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 18390145acc2SLinus Torvalds 18403ddcd056SLinus Torvalds /* 1841200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1842200e9ef7SLinus Torvalds * one character. 1843200e9ef7SLinus Torvalds */ 1844d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1845200e9ef7SLinus Torvalds { 1846200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1847200e9ef7SLinus Torvalds unsigned long len = 0, c; 1848200e9ef7SLinus Torvalds 1849200e9ef7SLinus Torvalds c = (unsigned char)*name; 1850200e9ef7SLinus Torvalds do { 1851200e9ef7SLinus Torvalds len++; 1852200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1853200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1854200e9ef7SLinus Torvalds } while (c && c != '/'); 1855d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 1856200e9ef7SLinus Torvalds } 1857200e9ef7SLinus Torvalds 1858bfcfaa77SLinus Torvalds #endif 1859bfcfaa77SLinus Torvalds 1860200e9ef7SLinus Torvalds /* 18611da177e4SLinus Torvalds * Name resolution. 1862ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1863ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 18641da177e4SLinus Torvalds * 1865ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1866ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 18671da177e4SLinus Torvalds */ 18686de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 18691da177e4SLinus Torvalds { 18701da177e4SLinus Torvalds int err; 18711da177e4SLinus Torvalds 18721da177e4SLinus Torvalds while (*name=='/') 18731da177e4SLinus Torvalds name++; 18741da177e4SLinus Torvalds if (!*name) 18759e18f10aSAl Viro return 0; 18761da177e4SLinus Torvalds 18771da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 18781da177e4SLinus Torvalds for(;;) { 1879d6bb3e90SLinus Torvalds u64 hash_len; 1880fe479a58SAl Viro int type; 18811da177e4SLinus Torvalds 188252094c8aSAl Viro err = may_lookup(nd); 18831da177e4SLinus Torvalds if (err) 18843595e234SAl Viro return err; 18851da177e4SLinus Torvalds 1886d6bb3e90SLinus Torvalds hash_len = hash_name(name); 18871da177e4SLinus Torvalds 1888fe479a58SAl Viro type = LAST_NORM; 1889d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 1890fe479a58SAl Viro case 2: 1891200e9ef7SLinus Torvalds if (name[1] == '.') { 1892fe479a58SAl Viro type = LAST_DOTDOT; 189316c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 189416c2cd71SAl Viro } 1895fe479a58SAl Viro break; 1896fe479a58SAl Viro case 1: 1897fe479a58SAl Viro type = LAST_DOT; 1898fe479a58SAl Viro } 18995a202bcdSAl Viro if (likely(type == LAST_NORM)) { 19005a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 190116c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 19025a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 1903a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 1904da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 19055a202bcdSAl Viro if (err < 0) 19063595e234SAl Viro return err; 1907d6bb3e90SLinus Torvalds hash_len = this.hash_len; 1908d6bb3e90SLinus Torvalds name = this.name; 19095a202bcdSAl Viro } 19105a202bcdSAl Viro } 1911fe479a58SAl Viro 1912d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 1913d6bb3e90SLinus Torvalds nd->last.name = name; 19145f4a6a69SAl Viro nd->last_type = type; 19155f4a6a69SAl Viro 1916d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 1917d6bb3e90SLinus Torvalds if (!*name) 1918bdf6cbf1SAl Viro goto OK; 1919200e9ef7SLinus Torvalds /* 1920200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1921200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1922200e9ef7SLinus Torvalds */ 1923200e9ef7SLinus Torvalds do { 1924d6bb3e90SLinus Torvalds name++; 1925d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 19268620c238SAl Viro if (unlikely(!*name)) { 19278620c238SAl Viro OK: 1928368ee9baSAl Viro /* pathname body, done */ 19298620c238SAl Viro if (!nd->depth) 19308620c238SAl Viro return 0; 19318620c238SAl Viro name = nd->stack[nd->depth - 1].name; 1932368ee9baSAl Viro /* trailing symlink, done */ 19338620c238SAl Viro if (!name) 19348620c238SAl Viro return 0; 19358620c238SAl Viro /* last component of nested symlink */ 19364693a547SAl Viro err = walk_component(nd, WALK_GET | WALK_PUT); 19378620c238SAl Viro } else { 19384693a547SAl Viro err = walk_component(nd, WALK_GET); 19398620c238SAl Viro } 1940ce57dfc1SAl Viro if (err < 0) 19413595e234SAl Viro return err; 1942fe479a58SAl Viro 1943ce57dfc1SAl Viro if (err) { 1944626de996SAl Viro const char *s = get_link(nd); 19455a460275SAl Viro 19463595e234SAl Viro if (unlikely(IS_ERR(s))) 19473595e234SAl Viro return PTR_ERR(s); 1948172a39a0SAl Viro err = 0; 194912b09578SAl Viro if (unlikely(!s)) { 195012b09578SAl Viro /* jumped */ 1951b9ff4429SAl Viro put_link(nd); 195212b09578SAl Viro } else { 1953071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 195432cd7468SAl Viro name = s; 19559e18f10aSAl Viro continue; 195648c8b0c5SAl Viro } 195731e6b01fSNick Piggin } 19583595e234SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) 19593595e234SAl Viro return -ENOTDIR; 19605f4a6a69SAl Viro } 1961ce57dfc1SAl Viro } 19621da177e4SLinus Torvalds 1963c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 196431e6b01fSNick Piggin { 196531e6b01fSNick Piggin int retval = 0; 1966c8a53ee5SAl Viro const char *s = nd->name->name; 196731e6b01fSNick Piggin 196831e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 1969980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 197031e6b01fSNick Piggin nd->depth = 0; 1971368ee9baSAl Viro nd->total_link_count = 0; 19725b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 1973b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 1974b18825a7SDavid Howells struct inode *inode = root->d_inode; 1975fd2f7cb5SAl Viro if (*s) { 197644b1d530SMiklos Szeredi if (!d_can_lookup(root)) 1977368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 19785b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 19795b6ca027SAl Viro if (retval) 1980368ee9baSAl Viro return ERR_PTR(retval); 198173d049a4SAl Viro } 19825b6ca027SAl Viro nd->path = nd->root; 19835b6ca027SAl Viro nd->inode = inode; 19845b6ca027SAl Viro if (flags & LOOKUP_RCU) { 19858b61e74fSAl Viro rcu_read_lock(); 19865b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 19878f47a016SAl Viro nd->root_seq = nd->seq; 198848a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 19895b6ca027SAl Viro } else { 19905b6ca027SAl Viro path_get(&nd->path); 19915b6ca027SAl Viro } 1992368ee9baSAl Viro return s; 19935b6ca027SAl Viro } 19945b6ca027SAl Viro 199531e6b01fSNick Piggin nd->root.mnt = NULL; 199631e6b01fSNick Piggin 199748a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 1998fd2f7cb5SAl Viro if (*s == '/') { 1999e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 20008b61e74fSAl Viro rcu_read_lock(); 20017bd88377SAl Viro nd->seq = set_root_rcu(nd); 2002e41f7d4eSAl Viro } else { 2003e41f7d4eSAl Viro set_root(nd); 2004e41f7d4eSAl Viro path_get(&nd->root); 2005e41f7d4eSAl Viro } 200631e6b01fSNick Piggin nd->path = nd->root; 2007c8a53ee5SAl Viro } else if (nd->dfd == AT_FDCWD) { 2008e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 200931e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2010c28cc364SNick Piggin unsigned seq; 201131e6b01fSNick Piggin 20128b61e74fSAl Viro rcu_read_lock(); 201331e6b01fSNick Piggin 2014c28cc364SNick Piggin do { 2015c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 201631e6b01fSNick Piggin nd->path = fs->pwd; 2017c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2018c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2019e41f7d4eSAl Viro } else { 2020e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2021e41f7d4eSAl Viro } 202231e6b01fSNick Piggin } else { 2023582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2024c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 202531e6b01fSNick Piggin struct dentry *dentry; 202631e6b01fSNick Piggin 20272903ff01SAl Viro if (!f.file) 2028368ee9baSAl Viro return ERR_PTR(-EBADF); 202931e6b01fSNick Piggin 20302903ff01SAl Viro dentry = f.file->f_path.dentry; 203131e6b01fSNick Piggin 2032fd2f7cb5SAl Viro if (*s) { 203344b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 20342903ff01SAl Viro fdput(f); 2035368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2036f52e0c11SAl Viro } 20372903ff01SAl Viro } 20382903ff01SAl Viro 20392903ff01SAl Viro nd->path = f.file->f_path; 2040e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 20418b61e74fSAl Viro rcu_read_lock(); 204234a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 204334a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 20445590ff0dSUlrich Drepper } else { 20452903ff01SAl Viro path_get(&nd->path); 204634a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 20471da177e4SLinus Torvalds } 204834a26b99SAl Viro fdput(f); 2049368ee9baSAl Viro return s; 2050e41f7d4eSAl Viro } 2051e41f7d4eSAl Viro 205231e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 20534023bfc9SAl Viro if (!(flags & LOOKUP_RCU)) 2054368ee9baSAl Viro return s; 20554023bfc9SAl Viro if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) 2056368ee9baSAl Viro return s; 20574023bfc9SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 20584023bfc9SAl Viro nd->root.mnt = NULL; 20594023bfc9SAl Viro rcu_read_unlock(); 2060368ee9baSAl Viro return ERR_PTR(-ECHILD); 20619b4a9b14SAl Viro } 20629b4a9b14SAl Viro 20633bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 206495fa25d9SAl Viro { 206595fa25d9SAl Viro const char *s; 2066fec2fa24SAl Viro int error = may_follow_link(nd); 2067deb106c6SAl Viro if (unlikely(error)) 20683bdba28bSAl Viro return ERR_PTR(error); 206995fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2070fab51e8aSAl Viro nd->stack[0].name = NULL; 20713b2e7f75SAl Viro s = get_link(nd); 2072deb106c6SAl Viro return s ? s : ""; 207395fa25d9SAl Viro } 207495fa25d9SAl Viro 2075caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2076bd92d7feSAl Viro { 2077bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2078bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2079bd92d7feSAl Viro 2080bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 2081deb106c6SAl Viro return walk_component(nd, 20824693a547SAl Viro nd->flags & LOOKUP_FOLLOW 20834693a547SAl Viro ? nd->depth 20844693a547SAl Viro ? WALK_PUT | WALK_GET 20854693a547SAl Viro : WALK_GET 20864693a547SAl Viro : 0); 2087bd92d7feSAl Viro } 2088bd92d7feSAl Viro 20899b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2090c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 20919b4a9b14SAl Viro { 2092c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2093bd92d7feSAl Viro int err; 209431e6b01fSNick Piggin 2095368ee9baSAl Viro if (IS_ERR(s)) 2096368ee9baSAl Viro return PTR_ERR(s); 20973bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 20983bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 20993bdba28bSAl Viro s = trailing_symlink(nd); 21003bdba28bSAl Viro if (IS_ERR(s)) { 21013bdba28bSAl Viro err = PTR_ERR(s); 21026d7b5aaeSAl Viro break; 2103bd92d7feSAl Viro } 2104bd92d7feSAl Viro } 21059f1fafeeSAl Viro if (!err) 21069f1fafeeSAl Viro err = complete_walk(nd); 2107bd92d7feSAl Viro 2108deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2109deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2110bd23a539SAl Viro err = -ENOTDIR; 2111625b6d10SAl Viro if (!err) { 2112625b6d10SAl Viro *path = nd->path; 2113625b6d10SAl Viro nd->path.mnt = NULL; 2114625b6d10SAl Viro nd->path.dentry = NULL; 2115625b6d10SAl Viro } 2116deb106c6SAl Viro terminate_walk(nd); 2117bd92d7feSAl Viro return err; 211831e6b01fSNick Piggin } 211931e6b01fSNick Piggin 2120625b6d10SAl Viro static int filename_lookup(int dfd, struct filename *name, unsigned flags, 21219ad1aaa6SAl Viro struct path *path, struct path *root) 2122873f1eedSJeff Layton { 2123894bc8c4SAl Viro int retval; 21249883d185SAl Viro struct nameidata nd; 2125abc9f5beSAl Viro if (IS_ERR(name)) 2126abc9f5beSAl Viro return PTR_ERR(name); 21279ad1aaa6SAl Viro if (unlikely(root)) { 21289ad1aaa6SAl Viro nd.root = *root; 21299ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 21309ad1aaa6SAl Viro } 21319883d185SAl Viro set_nameidata(&nd, dfd, name); 2132c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2133873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2134c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2135873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2136c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2137873f1eedSJeff Layton 2138873f1eedSJeff Layton if (likely(!retval)) 2139625b6d10SAl Viro audit_inode(name, path->dentry, flags & LOOKUP_PARENT); 21409883d185SAl Viro restore_nameidata(); 2141e4bd1c1aSAl Viro putname(name); 2142873f1eedSJeff Layton return retval; 2143873f1eedSJeff Layton } 2144873f1eedSJeff Layton 21458bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2146c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2147391172c4SAl Viro struct path *parent) 21488bcb77faSAl Viro { 2149c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2150368ee9baSAl Viro int err; 2151368ee9baSAl Viro if (IS_ERR(s)) 2152368ee9baSAl Viro return PTR_ERR(s); 2153368ee9baSAl Viro err = link_path_walk(s, nd); 21548bcb77faSAl Viro if (!err) 21558bcb77faSAl Viro err = complete_walk(nd); 2156391172c4SAl Viro if (!err) { 2157391172c4SAl Viro *parent = nd->path; 2158391172c4SAl Viro nd->path.mnt = NULL; 2159391172c4SAl Viro nd->path.dentry = NULL; 2160391172c4SAl Viro } 2161deb106c6SAl Viro terminate_walk(nd); 21628bcb77faSAl Viro return err; 21638bcb77faSAl Viro } 21648bcb77faSAl Viro 21655c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2166391172c4SAl Viro unsigned int flags, struct path *parent, 2167391172c4SAl Viro struct qstr *last, int *type) 21688bcb77faSAl Viro { 21698bcb77faSAl Viro int retval; 21709883d185SAl Viro struct nameidata nd; 21718bcb77faSAl Viro 21725c31b6ceSAl Viro if (IS_ERR(name)) 21735c31b6ceSAl Viro return name; 21749883d185SAl Viro set_nameidata(&nd, dfd, name); 2175c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 21768bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2177c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 21788bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2179c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2180391172c4SAl Viro if (likely(!retval)) { 2181391172c4SAl Viro *last = nd.last; 2182391172c4SAl Viro *type = nd.last_type; 2183391172c4SAl Viro audit_inode(name, parent->dentry, LOOKUP_PARENT); 21845c31b6ceSAl Viro } else { 21855c31b6ceSAl Viro putname(name); 21865c31b6ceSAl Viro name = ERR_PTR(retval); 2187391172c4SAl Viro } 21889883d185SAl Viro restore_nameidata(); 21895c31b6ceSAl Viro return name; 21908bcb77faSAl Viro } 21918bcb77faSAl Viro 219279714f72SAl Viro /* does lookup, returns the object with parent locked */ 219379714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 21945590ff0dSUlrich Drepper { 21955c31b6ceSAl Viro struct filename *filename; 21965c31b6ceSAl Viro struct dentry *d; 2197391172c4SAl Viro struct qstr last; 2198391172c4SAl Viro int type; 219951689104SPaul Moore 22005c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 22015c31b6ceSAl Viro &last, &type); 220251689104SPaul Moore if (IS_ERR(filename)) 220351689104SPaul Moore return ERR_CAST(filename); 22045c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2205391172c4SAl Viro path_put(path); 22065c31b6ceSAl Viro putname(filename); 22075c31b6ceSAl Viro return ERR_PTR(-EINVAL); 220879714f72SAl Viro } 2209391172c4SAl Viro mutex_lock_nested(&path->dentry->d_inode->i_mutex, I_MUTEX_PARENT); 2210391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 221179714f72SAl Viro if (IS_ERR(d)) { 2212391172c4SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 2213391172c4SAl Viro path_put(path); 221479714f72SAl Viro } 221551689104SPaul Moore putname(filename); 221679714f72SAl Viro return d; 22175590ff0dSUlrich Drepper } 22185590ff0dSUlrich Drepper 2219d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2220d1811465SAl Viro { 2221abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2222abc9f5beSAl Viro flags, path, NULL); 2223d1811465SAl Viro } 22244d359507SAl Viro EXPORT_SYMBOL(kern_path); 2225d1811465SAl Viro 222616f18200SJosef 'Jeff' Sipek /** 222716f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 222816f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 222916f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 223016f18200SJosef 'Jeff' Sipek * @name: pointer to file name 223116f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2232e0a01249SAl Viro * @path: pointer to struct path to fill 223316f18200SJosef 'Jeff' Sipek */ 223416f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 223516f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2236e0a01249SAl Viro struct path *path) 223716f18200SJosef 'Jeff' Sipek { 22389ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 22399ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2240abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2241abc9f5beSAl Viro flags , path, &root); 224216f18200SJosef 'Jeff' Sipek } 22434d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 224416f18200SJosef 'Jeff' Sipek 2245eead1911SChristoph Hellwig /** 2246a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2247eead1911SChristoph Hellwig * @name: pathname component to lookup 2248eead1911SChristoph Hellwig * @base: base directory to lookup from 2249eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2250eead1911SChristoph Hellwig * 2251a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 22529e7543e9SAl Viro * not be called by generic code. 2253eead1911SChristoph Hellwig */ 2254057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2255057f6c01SJames Morris { 2256057f6c01SJames Morris struct qstr this; 22576a96ba54SAl Viro unsigned int c; 2258cda309deSMiklos Szeredi int err; 2259057f6c01SJames Morris 22602f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 22612f9092e1SDavid Woodhouse 22626a96ba54SAl Viro this.name = name; 22636a96ba54SAl Viro this.len = len; 22640145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 22656a96ba54SAl Viro if (!len) 22666a96ba54SAl Viro return ERR_PTR(-EACCES); 22676a96ba54SAl Viro 226821d8a15aSAl Viro if (unlikely(name[0] == '.')) { 226921d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 227021d8a15aSAl Viro return ERR_PTR(-EACCES); 227121d8a15aSAl Viro } 227221d8a15aSAl Viro 22736a96ba54SAl Viro while (len--) { 22746a96ba54SAl Viro c = *(const unsigned char *)name++; 22756a96ba54SAl Viro if (c == '/' || c == '\0') 22766a96ba54SAl Viro return ERR_PTR(-EACCES); 22776a96ba54SAl Viro } 22785a202bcdSAl Viro /* 22795a202bcdSAl Viro * See if the low-level filesystem might want 22805a202bcdSAl Viro * to use its own hash.. 22815a202bcdSAl Viro */ 22825a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2283da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 22845a202bcdSAl Viro if (err < 0) 22855a202bcdSAl Viro return ERR_PTR(err); 22865a202bcdSAl Viro } 2287eead1911SChristoph Hellwig 2288cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2289cda309deSMiklos Szeredi if (err) 2290cda309deSMiklos Szeredi return ERR_PTR(err); 2291cda309deSMiklos Szeredi 229272bd866aSAl Viro return __lookup_hash(&this, base, 0); 2293057f6c01SJames Morris } 22944d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2295057f6c01SJames Morris 22961fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 22971fa1e7f6SAndy Whitcroft struct path *path, int *empty) 22981da177e4SLinus Torvalds { 2299abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2300abc9f5beSAl Viro flags, path, NULL); 23011da177e4SLinus Torvalds } 2302b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 23031fa1e7f6SAndy Whitcroft 2304873f1eedSJeff Layton /* 2305873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2306873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2307873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2308873f1eedSJeff Layton * path-walking is complete. 2309873f1eedSJeff Layton */ 2310a2ec4a2dSAl Viro static inline struct filename * 2311f5beed75SAl Viro user_path_parent(int dfd, const char __user *path, 2312f5beed75SAl Viro struct path *parent, 2313f5beed75SAl Viro struct qstr *last, 2314f5beed75SAl Viro int *type, 23159e790bd6SJeff Layton unsigned int flags) 23162ad94ae6SAl Viro { 23179e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 23185c31b6ceSAl Viro return filename_parentat(dfd, getname(path), flags & LOOKUP_REVAL, 23195c31b6ceSAl Viro parent, last, type); 23202ad94ae6SAl Viro } 23212ad94ae6SAl Viro 23228033426eSJeff Layton /** 2323197df04cSAl Viro * mountpoint_last - look up last component for umount 23248033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 23258033426eSJeff Layton * @path: pointer to container for result 23268033426eSJeff Layton * 23278033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 23288033426eSJeff Layton * need to resolve the path without doing any revalidation. 23298033426eSJeff Layton * 23308033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 23318033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 23328033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 23338033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 23348033426eSJeff Layton * bogus and it doesn't exist. 23358033426eSJeff Layton * 23368033426eSJeff Layton * Returns: 23378033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 23388033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 23398033426eSJeff Layton * put in this case. 23408033426eSJeff Layton * 23418033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 23428033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 23438033426eSJeff Layton * The nd->path reference will also be put. 23448033426eSJeff Layton * 23458033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 23468033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 23478033426eSJeff Layton * to the link, and nd->path will *not* be put. 23488033426eSJeff Layton */ 23498033426eSJeff Layton static int 2350197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 23518033426eSJeff Layton { 23528033426eSJeff Layton int error = 0; 23538033426eSJeff Layton struct dentry *dentry; 23548033426eSJeff Layton struct dentry *dir = nd->path.dentry; 23558033426eSJeff Layton 235635759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 235735759521SAl Viro if (nd->flags & LOOKUP_RCU) { 23586e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 2359deb106c6SAl Viro return -ECHILD; 23608033426eSJeff Layton } 23618033426eSJeff Layton 23628033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 23638033426eSJeff Layton 23648033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 23658033426eSJeff Layton error = handle_dots(nd, nd->last_type); 236635759521SAl Viro if (error) 2367deb106c6SAl Viro return error; 23688033426eSJeff Layton dentry = dget(nd->path.dentry); 236935759521SAl Viro goto done; 23708033426eSJeff Layton } 23718033426eSJeff Layton 23728033426eSJeff Layton mutex_lock(&dir->d_inode->i_mutex); 23738033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 23748033426eSJeff Layton if (!dentry) { 23758033426eSJeff Layton /* 23768033426eSJeff Layton * No cached dentry. Mounted dentries are pinned in the cache, 23778033426eSJeff Layton * so that means that this dentry is probably a symlink or the 23788033426eSJeff Layton * path doesn't actually point to a mounted dentry. 23798033426eSJeff Layton */ 23808033426eSJeff Layton dentry = d_alloc(dir, &nd->last); 23818033426eSJeff Layton if (!dentry) { 2382bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 2383deb106c6SAl Viro return -ENOMEM; 23848033426eSJeff Layton } 238535759521SAl Viro dentry = lookup_real(dir->d_inode, dentry, nd->flags); 2386bcceeebaSDave Jones if (IS_ERR(dentry)) { 2387bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 2388deb106c6SAl Viro return PTR_ERR(dentry); 23898033426eSJeff Layton } 2390bcceeebaSDave Jones } 23918033426eSJeff Layton mutex_unlock(&dir->d_inode->i_mutex); 23928033426eSJeff Layton 239335759521SAl Viro done: 2394698934dfSDavid Howells if (d_is_negative(dentry)) { 23958033426eSJeff Layton dput(dentry); 2396deb106c6SAl Viro return -ENOENT; 239735759521SAl Viro } 2398191d7f73SAl Viro if (nd->depth) 2399191d7f73SAl Viro put_link(nd); 24008033426eSJeff Layton path->dentry = dentry; 2401295dc39dSVasily Averin path->mnt = nd->path.mnt; 2402181548c0SAl Viro error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW, 2403181548c0SAl Viro d_backing_inode(dentry), 0); 2404deb106c6SAl Viro if (unlikely(error)) 2405d63ff28fSAl Viro return error; 2406295dc39dSVasily Averin mntget(path->mnt); 24078033426eSJeff Layton follow_mount(path); 2408deb106c6SAl Viro return 0; 24098033426eSJeff Layton } 24108033426eSJeff Layton 24118033426eSJeff Layton /** 2412197df04cSAl Viro * path_mountpoint - look up a path to be umounted 2413c8a53ee5SAl Viro * @nameidata: lookup context 24148033426eSJeff Layton * @flags: lookup flags 2415c8a53ee5SAl Viro * @path: pointer to container for result 24168033426eSJeff Layton * 24178033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2418606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 24198033426eSJeff Layton */ 24208033426eSJeff Layton static int 2421c8a53ee5SAl Viro path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) 24228033426eSJeff Layton { 2423c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2424368ee9baSAl Viro int err; 2425368ee9baSAl Viro if (IS_ERR(s)) 2426368ee9baSAl Viro return PTR_ERR(s); 24273bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 24283bdba28bSAl Viro (err = mountpoint_last(nd, path)) > 0) { 24293bdba28bSAl Viro s = trailing_symlink(nd); 24303bdba28bSAl Viro if (IS_ERR(s)) { 24313bdba28bSAl Viro err = PTR_ERR(s); 24328033426eSJeff Layton break; 24338033426eSJeff Layton } 24343bdba28bSAl Viro } 2435deb106c6SAl Viro terminate_walk(nd); 24368033426eSJeff Layton return err; 24378033426eSJeff Layton } 24388033426eSJeff Layton 24392d864651SAl Viro static int 2440668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 24412d864651SAl Viro unsigned int flags) 24422d864651SAl Viro { 24439883d185SAl Viro struct nameidata nd; 2444cbaab2dbSAl Viro int error; 2445668696dcSAl Viro if (IS_ERR(name)) 2446668696dcSAl Viro return PTR_ERR(name); 24479883d185SAl Viro set_nameidata(&nd, dfd, name); 2448c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); 24492d864651SAl Viro if (unlikely(error == -ECHILD)) 2450c8a53ee5SAl Viro error = path_mountpoint(&nd, flags, path); 24512d864651SAl Viro if (unlikely(error == -ESTALE)) 2452c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); 24532d864651SAl Viro if (likely(!error)) 2454668696dcSAl Viro audit_inode(name, path->dentry, 0); 24559883d185SAl Viro restore_nameidata(); 2456668696dcSAl Viro putname(name); 24572d864651SAl Viro return error; 24582d864651SAl Viro } 24592d864651SAl Viro 24608033426eSJeff Layton /** 2461197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 24628033426eSJeff Layton * @dfd: directory file descriptor 24638033426eSJeff Layton * @name: pathname from userland 24648033426eSJeff Layton * @flags: lookup flags 24658033426eSJeff Layton * @path: pointer to container to hold result 24668033426eSJeff Layton * 24678033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 24688033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 24698033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 24708033426eSJeff Layton * and avoid revalidating the last component. 24718033426eSJeff Layton * 24728033426eSJeff Layton * Returns 0 and populates "path" on success. 24738033426eSJeff Layton */ 24748033426eSJeff Layton int 2475197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 24768033426eSJeff Layton struct path *path) 24778033426eSJeff Layton { 2478cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 24798033426eSJeff Layton } 24808033426eSJeff Layton 24812d864651SAl Viro int 24822d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 24832d864651SAl Viro unsigned int flags) 24842d864651SAl Viro { 2485cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 24862d864651SAl Viro } 24872d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 24882d864651SAl Viro 2489cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 24901da177e4SLinus Torvalds { 24918e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2492da9592edSDavid Howells 24938e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 24941da177e4SLinus Torvalds return 0; 24958e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 24961da177e4SLinus Torvalds return 0; 249723adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 24981da177e4SLinus Torvalds } 2499cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 25001da177e4SLinus Torvalds 25011da177e4SLinus Torvalds /* 25021da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 25031da177e4SLinus Torvalds * whether the type of victim is right. 25041da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 25051da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 25061da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 25071da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 25081da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 25091da177e4SLinus Torvalds * a. be owner of dir, or 25101da177e4SLinus Torvalds * b. be owner of victim, or 25111da177e4SLinus Torvalds * c. have CAP_FOWNER capability 25121da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 25131da177e4SLinus Torvalds * links pointing to it. 25141da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 25151da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 25161da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 25171da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 25181da177e4SLinus Torvalds * nfs_async_unlink(). 25191da177e4SLinus Torvalds */ 2520b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 25211da177e4SLinus Torvalds { 252263afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 25231da177e4SLinus Torvalds int error; 25241da177e4SLinus Torvalds 2525b18825a7SDavid Howells if (d_is_negative(victim)) 25261da177e4SLinus Torvalds return -ENOENT; 2527b18825a7SDavid Howells BUG_ON(!inode); 25281da177e4SLinus Torvalds 25291da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 25304fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 25311da177e4SLinus Torvalds 2532f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 25331da177e4SLinus Torvalds if (error) 25341da177e4SLinus Torvalds return error; 25351da177e4SLinus Torvalds if (IS_APPEND(dir)) 25361da177e4SLinus Torvalds return -EPERM; 2537b18825a7SDavid Howells 2538b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2539b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 25401da177e4SLinus Torvalds return -EPERM; 25411da177e4SLinus Torvalds if (isdir) { 254244b1d530SMiklos Szeredi if (!d_is_dir(victim)) 25431da177e4SLinus Torvalds return -ENOTDIR; 25441da177e4SLinus Torvalds if (IS_ROOT(victim)) 25451da177e4SLinus Torvalds return -EBUSY; 254644b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 25471da177e4SLinus Torvalds return -EISDIR; 25481da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25491da177e4SLinus Torvalds return -ENOENT; 25501da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 25511da177e4SLinus Torvalds return -EBUSY; 25521da177e4SLinus Torvalds return 0; 25531da177e4SLinus Torvalds } 25541da177e4SLinus Torvalds 25551da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 25561da177e4SLinus Torvalds * dir. 25571da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 25581da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 25591da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 25601da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 25611da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 25621da177e4SLinus Torvalds */ 2563a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 25641da177e4SLinus Torvalds { 256514e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 25661da177e4SLinus Torvalds if (child->d_inode) 25671da177e4SLinus Torvalds return -EEXIST; 25681da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25691da177e4SLinus Torvalds return -ENOENT; 2570f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 25711da177e4SLinus Torvalds } 25721da177e4SLinus Torvalds 25731da177e4SLinus Torvalds /* 25741da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 25751da177e4SLinus Torvalds */ 25761da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 25771da177e4SLinus Torvalds { 25781da177e4SLinus Torvalds struct dentry *p; 25791da177e4SLinus Torvalds 25801da177e4SLinus Torvalds if (p1 == p2) { 2581f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 25821da177e4SLinus Torvalds return NULL; 25831da177e4SLinus Torvalds } 25841da177e4SLinus Torvalds 2585a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25861da177e4SLinus Torvalds 2587e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2588e2761a11SOGAWA Hirofumi if (p) { 2589f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2590f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 25911da177e4SLinus Torvalds return p; 25921da177e4SLinus Torvalds } 25931da177e4SLinus Torvalds 2594e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2595e2761a11SOGAWA Hirofumi if (p) { 2596f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2597f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 25981da177e4SLinus Torvalds return p; 25991da177e4SLinus Torvalds } 26001da177e4SLinus Torvalds 2601f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2602d1b72cc6SMiklos Szeredi mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); 26031da177e4SLinus Torvalds return NULL; 26041da177e4SLinus Torvalds } 26054d359507SAl Viro EXPORT_SYMBOL(lock_rename); 26061da177e4SLinus Torvalds 26071da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 26081da177e4SLinus Torvalds { 26091b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 26101da177e4SLinus Torvalds if (p1 != p2) { 26111b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2612a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 26131da177e4SLinus Torvalds } 26141da177e4SLinus Torvalds } 26154d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 26161da177e4SLinus Torvalds 26174acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2618312b63fbSAl Viro bool want_excl) 26191da177e4SLinus Torvalds { 2620a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 26211da177e4SLinus Torvalds if (error) 26221da177e4SLinus Torvalds return error; 26231da177e4SLinus Torvalds 2624acfa4380SAl Viro if (!dir->i_op->create) 26251da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 26261da177e4SLinus Torvalds mode &= S_IALLUGO; 26271da177e4SLinus Torvalds mode |= S_IFREG; 26281da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 26291da177e4SLinus Torvalds if (error) 26301da177e4SLinus Torvalds return error; 2631312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2632a74574aaSStephen Smalley if (!error) 2633f38aa942SAmy Griffis fsnotify_create(dir, dentry); 26341da177e4SLinus Torvalds return error; 26351da177e4SLinus Torvalds } 26364d359507SAl Viro EXPORT_SYMBOL(vfs_create); 26371da177e4SLinus Torvalds 263873d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 26391da177e4SLinus Torvalds { 26403fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 26411da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 26421da177e4SLinus Torvalds int error; 26431da177e4SLinus Torvalds 2644bcda7652SAl Viro /* O_PATH? */ 2645bcda7652SAl Viro if (!acc_mode) 2646bcda7652SAl Viro return 0; 2647bcda7652SAl Viro 26481da177e4SLinus Torvalds if (!inode) 26491da177e4SLinus Torvalds return -ENOENT; 26501da177e4SLinus Torvalds 2651c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2652c8fe8f30SChristoph Hellwig case S_IFLNK: 26531da177e4SLinus Torvalds return -ELOOP; 2654c8fe8f30SChristoph Hellwig case S_IFDIR: 2655c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 26561da177e4SLinus Torvalds return -EISDIR; 2657c8fe8f30SChristoph Hellwig break; 2658c8fe8f30SChristoph Hellwig case S_IFBLK: 2659c8fe8f30SChristoph Hellwig case S_IFCHR: 26603fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 26611da177e4SLinus Torvalds return -EACCES; 2662c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2663c8fe8f30SChristoph Hellwig case S_IFIFO: 2664c8fe8f30SChristoph Hellwig case S_IFSOCK: 26651da177e4SLinus Torvalds flag &= ~O_TRUNC; 2666c8fe8f30SChristoph Hellwig break; 26674a3fd211SDave Hansen } 2668b41572e9SDave Hansen 26693fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2670b41572e9SDave Hansen if (error) 2671b41572e9SDave Hansen return error; 26726146f0d5SMimi Zohar 26731da177e4SLinus Torvalds /* 26741da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 26751da177e4SLinus Torvalds */ 26761da177e4SLinus Torvalds if (IS_APPEND(inode)) { 26778737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 26787715b521SAl Viro return -EPERM; 26791da177e4SLinus Torvalds if (flag & O_TRUNC) 26807715b521SAl Viro return -EPERM; 26811da177e4SLinus Torvalds } 26821da177e4SLinus Torvalds 26831da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 26842e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 26857715b521SAl Viro return -EPERM; 26861da177e4SLinus Torvalds 2687f3c7691eSJ. Bruce Fields return 0; 26887715b521SAl Viro } 26897715b521SAl Viro 2690e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 26917715b521SAl Viro { 2692e1181ee6SJeff Layton struct path *path = &filp->f_path; 26937715b521SAl Viro struct inode *inode = path->dentry->d_inode; 26947715b521SAl Viro int error = get_write_access(inode); 26951da177e4SLinus Torvalds if (error) 26967715b521SAl Viro return error; 26971da177e4SLinus Torvalds /* 26981da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 26991da177e4SLinus Torvalds */ 2700d7a06983SJeff Layton error = locks_verify_locked(filp); 2701be6d3e56SKentaro Takeda if (!error) 2702ea0d3ab2STetsuo Handa error = security_path_truncate(path); 27031da177e4SLinus Torvalds if (!error) { 27047715b521SAl Viro error = do_truncate(path->dentry, 0, 2705d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2706e1181ee6SJeff Layton filp); 27071da177e4SLinus Torvalds } 27081da177e4SLinus Torvalds put_write_access(inode); 2709acd0c935SMimi Zohar return error; 27101da177e4SLinus Torvalds } 27111da177e4SLinus Torvalds 2712d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2713d57999e1SDave Hansen { 27148a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 27158a5e929dSAl Viro flag--; 2716d57999e1SDave Hansen return flag; 2717d57999e1SDave Hansen } 2718d57999e1SDave Hansen 2719d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2720d18e9008SMiklos Szeredi { 2721d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2722d18e9008SMiklos Szeredi if (error) 2723d18e9008SMiklos Szeredi return error; 2724d18e9008SMiklos Szeredi 2725d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2726d18e9008SMiklos Szeredi if (error) 2727d18e9008SMiklos Szeredi return error; 2728d18e9008SMiklos Szeredi 2729d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2730d18e9008SMiklos Szeredi } 2731d18e9008SMiklos Szeredi 27321acf0af9SDavid Howells /* 27331acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 27341acf0af9SDavid Howells * dentry. 27351acf0af9SDavid Howells * 27361acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 27371acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 27381acf0af9SDavid Howells * 27391acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 27401acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 27411acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 27421acf0af9SDavid Howells * 27431acf0af9SDavid Howells * Returns an error code otherwise. 27441acf0af9SDavid Howells */ 27452675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 274630d90494SAl Viro struct path *path, struct file *file, 2747015c3bbcSMiklos Szeredi const struct open_flags *op, 274864894cf8SAl Viro bool got_write, bool need_lookup, 274947237687SAl Viro int *opened) 2750d18e9008SMiklos Szeredi { 2751d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2752d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2753d18e9008SMiklos Szeredi umode_t mode; 2754d18e9008SMiklos Szeredi int error; 2755d18e9008SMiklos Szeredi int acc_mode; 2756d18e9008SMiklos Szeredi int create_error = 0; 2757d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2758116cc022SMiklos Szeredi bool excl; 2759d18e9008SMiklos Szeredi 2760d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2761d18e9008SMiklos Szeredi 2762d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2763d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 27642675a4ebSAl Viro error = -ENOENT; 2765d18e9008SMiklos Szeredi goto out; 2766d18e9008SMiklos Szeredi } 2767d18e9008SMiklos Szeredi 276862b259d8SMiklos Szeredi mode = op->mode; 2769d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2770d18e9008SMiklos Szeredi mode &= ~current_umask(); 2771d18e9008SMiklos Szeredi 2772116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2773116cc022SMiklos Szeredi if (excl) 2774d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2775d18e9008SMiklos Szeredi 2776d18e9008SMiklos Szeredi /* 2777d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2778d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2779d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2780d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2781d18e9008SMiklos Szeredi * 2782d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2783d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2784d18e9008SMiklos Szeredi */ 278564894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 278664894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 278764894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2788d18e9008SMiklos Szeredi /* 2789d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2790d18e9008SMiklos Szeredi * back to lookup + open 2791d18e9008SMiklos Szeredi */ 2792d18e9008SMiklos Szeredi goto no_open; 2793d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2794d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 279564894cf8SAl Viro create_error = -EROFS; 2796d18e9008SMiklos Szeredi goto no_open; 2797d18e9008SMiklos Szeredi } else { 2798d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 279964894cf8SAl Viro create_error = -EROFS; 2800d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2801d18e9008SMiklos Szeredi } 2802d18e9008SMiklos Szeredi } 2803d18e9008SMiklos Szeredi 2804d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 280538227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2806d18e9008SMiklos Szeredi if (error) { 2807d18e9008SMiklos Szeredi create_error = error; 2808d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2809d18e9008SMiklos Szeredi goto no_open; 2810d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2811d18e9008SMiklos Szeredi } 2812d18e9008SMiklos Szeredi } 2813d18e9008SMiklos Szeredi 2814d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2815d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2816d18e9008SMiklos Szeredi 281730d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 281830d90494SAl Viro file->f_path.mnt = nd->path.mnt; 281930d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 282047237687SAl Viro opened); 2821d9585277SAl Viro if (error < 0) { 2822d9585277SAl Viro if (create_error && error == -ENOENT) 2823d9585277SAl Viro error = create_error; 2824d18e9008SMiklos Szeredi goto out; 2825d18e9008SMiklos Szeredi } 2826d18e9008SMiklos Szeredi 2827d9585277SAl Viro if (error) { /* returned 1, that is */ 282830d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 28292675a4ebSAl Viro error = -EIO; 2830d18e9008SMiklos Szeredi goto out; 2831d18e9008SMiklos Szeredi } 283230d90494SAl Viro if (file->f_path.dentry) { 2833d18e9008SMiklos Szeredi dput(dentry); 283430d90494SAl Viro dentry = file->f_path.dentry; 2835d18e9008SMiklos Szeredi } 283603da633aSAl Viro if (*opened & FILE_CREATED) 283703da633aSAl Viro fsnotify_create(dir, dentry); 283803da633aSAl Viro if (!dentry->d_inode) { 283903da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 284003da633aSAl Viro if (create_error) { 284162b2ce96SSage Weil error = create_error; 284262b2ce96SSage Weil goto out; 284362b2ce96SSage Weil } 284403da633aSAl Viro } else { 284503da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 284603da633aSAl Viro error = -EEXIST; 284703da633aSAl Viro goto out; 284803da633aSAl Viro } 284903da633aSAl Viro } 2850d18e9008SMiklos Szeredi goto looked_up; 2851d18e9008SMiklos Szeredi } 2852d18e9008SMiklos Szeredi 2853d18e9008SMiklos Szeredi /* 2854d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2855d18e9008SMiklos Szeredi * here. 2856d18e9008SMiklos Szeredi */ 285703da633aSAl Viro acc_mode = op->acc_mode; 285803da633aSAl Viro if (*opened & FILE_CREATED) { 285903da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 286003da633aSAl Viro fsnotify_create(dir, dentry); 286103da633aSAl Viro acc_mode = MAY_OPEN; 286203da633aSAl Viro } 28632675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 28642675a4ebSAl Viro if (error) 28652675a4ebSAl Viro fput(file); 2866d18e9008SMiklos Szeredi 2867d18e9008SMiklos Szeredi out: 2868d18e9008SMiklos Szeredi dput(dentry); 28692675a4ebSAl Viro return error; 2870d18e9008SMiklos Szeredi 2871d18e9008SMiklos Szeredi no_open: 2872d18e9008SMiklos Szeredi if (need_lookup) { 287372bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2874d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 28752675a4ebSAl Viro return PTR_ERR(dentry); 2876d18e9008SMiklos Szeredi 2877d18e9008SMiklos Szeredi if (create_error) { 2878d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2879d18e9008SMiklos Szeredi 28802675a4ebSAl Viro error = create_error; 2881d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2882d18e9008SMiklos Szeredi if (!dentry->d_inode) 2883d18e9008SMiklos Szeredi goto out; 2884d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2885d18e9008SMiklos Szeredi goto out; 2886d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2887e36cb0b8SDavid Howells d_is_reg(dentry)) { 2888d18e9008SMiklos Szeredi goto out; 2889d18e9008SMiklos Szeredi } 2890d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2891d18e9008SMiklos Szeredi } 2892d18e9008SMiklos Szeredi } 2893d18e9008SMiklos Szeredi looked_up: 2894d18e9008SMiklos Szeredi path->dentry = dentry; 2895d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 28962675a4ebSAl Viro return 1; 2897d18e9008SMiklos Szeredi } 2898d18e9008SMiklos Szeredi 289931e6b01fSNick Piggin /* 29001acf0af9SDavid Howells * Look up and maybe create and open the last component. 2901d58ffd35SMiklos Szeredi * 2902d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2903d58ffd35SMiklos Szeredi * 29041acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 29051acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 29061acf0af9SDavid Howells * 29071acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 29081acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 29091acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 29101acf0af9SDavid Howells * specified then a negative dentry may be returned. 29111acf0af9SDavid Howells * 29121acf0af9SDavid Howells * An error code is returned otherwise. 29131acf0af9SDavid Howells * 29141acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 29151acf0af9SDavid Howells * cleared otherwise prior to returning. 2916d58ffd35SMiklos Szeredi */ 29172675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 291830d90494SAl Viro struct file *file, 2919d58ffd35SMiklos Szeredi const struct open_flags *op, 292064894cf8SAl Viro bool got_write, int *opened) 2921d58ffd35SMiklos Szeredi { 2922d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 292354ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2924d58ffd35SMiklos Szeredi struct dentry *dentry; 2925d58ffd35SMiklos Szeredi int error; 292654ef4872SMiklos Szeredi bool need_lookup; 2927d58ffd35SMiklos Szeredi 292847237687SAl Viro *opened &= ~FILE_CREATED; 2929201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2930d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 29312675a4ebSAl Viro return PTR_ERR(dentry); 2932d58ffd35SMiklos Szeredi 2933d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2934d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2935d18e9008SMiklos Szeredi goto out_no_open; 2936d18e9008SMiklos Szeredi 2937d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 293864894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 293947237687SAl Viro need_lookup, opened); 2940d18e9008SMiklos Szeredi } 2941d18e9008SMiklos Szeredi 294254ef4872SMiklos Szeredi if (need_lookup) { 294354ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 294454ef4872SMiklos Szeredi 294572bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 294654ef4872SMiklos Szeredi if (IS_ERR(dentry)) 29472675a4ebSAl Viro return PTR_ERR(dentry); 294854ef4872SMiklos Szeredi } 294954ef4872SMiklos Szeredi 2950d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2951d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2952d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2953d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2954d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2955d58ffd35SMiklos Szeredi /* 2956d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2957d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2958d58ffd35SMiklos Szeredi * the time when the file is created and when 2959d58ffd35SMiklos Szeredi * a permanent write count is taken through 2960015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 2961d58ffd35SMiklos Szeredi */ 296264894cf8SAl Viro if (!got_write) { 296364894cf8SAl Viro error = -EROFS; 2964d58ffd35SMiklos Szeredi goto out_dput; 296564894cf8SAl Viro } 296647237687SAl Viro *opened |= FILE_CREATED; 2967d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2968d58ffd35SMiklos Szeredi if (error) 2969d58ffd35SMiklos Szeredi goto out_dput; 2970312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 2971312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 2972d58ffd35SMiklos Szeredi if (error) 2973d58ffd35SMiklos Szeredi goto out_dput; 2974d58ffd35SMiklos Szeredi } 2975d18e9008SMiklos Szeredi out_no_open: 2976d58ffd35SMiklos Szeredi path->dentry = dentry; 2977d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 29782675a4ebSAl Viro return 1; 2979d58ffd35SMiklos Szeredi 2980d58ffd35SMiklos Szeredi out_dput: 2981d58ffd35SMiklos Szeredi dput(dentry); 29822675a4ebSAl Viro return error; 2983d58ffd35SMiklos Szeredi } 2984d58ffd35SMiklos Szeredi 2985d58ffd35SMiklos Szeredi /* 2986fe2d35ffSAl Viro * Handle the last step of open() 298731e6b01fSNick Piggin */ 2988896475d5SAl Viro static int do_last(struct nameidata *nd, 298930d90494SAl Viro struct file *file, const struct open_flags *op, 299076ae2a5aSAl Viro int *opened) 2991fb1cc555SAl Viro { 2992a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2993ca344a89SAl Viro int open_flag = op->open_flag; 299477d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 299564894cf8SAl Viro bool got_write = false; 2996bcda7652SAl Viro int acc_mode = op->acc_mode; 2997254cf582SAl Viro unsigned seq; 2998a1eb3315SMiklos Szeredi struct inode *inode; 299916b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 3000896475d5SAl Viro struct path path; 300116b1c1cdSMiklos Szeredi bool retried = false; 300216c2cd71SAl Viro int error; 3003fb1cc555SAl Viro 3004c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3005c3e380b0SAl Viro nd->flags |= op->intent; 3006c3e380b0SAl Viro 3007bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3008fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3009deb106c6SAl Viro if (unlikely(error)) 30102675a4ebSAl Viro return error; 3011e83db167SMiklos Szeredi goto finish_open; 30121f36f774SAl Viro } 3013a2c36b45SAl Viro 3014ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3015fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3016fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3017fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3018254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 301971574865SMiklos Szeredi if (likely(!error)) 302071574865SMiklos Szeredi goto finish_lookup; 302171574865SMiklos Szeredi 3022ce57dfc1SAl Viro if (error < 0) 3023deb106c6SAl Viro return error; 3024a1eb3315SMiklos Szeredi 302537d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 3026b6183df7SMiklos Szeredi } else { 3027fe2d35ffSAl Viro /* create side of things */ 3028a3fbbde7SAl Viro /* 3029b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3030b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3031b6183df7SMiklos Szeredi * about to look up 3032a3fbbde7SAl Viro */ 30339f1fafeeSAl Viro error = complete_walk(nd); 3034e8bb73dfSAl Viro if (error) 30352675a4ebSAl Viro return error; 3036fe2d35ffSAl Viro 303776ae2a5aSAl Viro audit_inode(nd->name, dir, LOOKUP_PARENT); 30381f36f774SAl Viro /* trailing slashes? */ 3039deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3040deb106c6SAl Viro return -EISDIR; 3041b6183df7SMiklos Szeredi } 30421f36f774SAl Viro 304316b1c1cdSMiklos Szeredi retry_lookup: 304464894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 304564894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 304664894cf8SAl Viro if (!error) 304764894cf8SAl Viro got_write = true; 304864894cf8SAl Viro /* 304964894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 305064894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 305164894cf8SAl Viro * dropping this one anyway. 305264894cf8SAl Viro */ 305364894cf8SAl Viro } 3054a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 3055896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 3056fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 3057fb1cc555SAl Viro 30582675a4ebSAl Viro if (error <= 0) { 30592675a4ebSAl Viro if (error) 3060d58ffd35SMiklos Szeredi goto out; 30616c0d46c4SAl Viro 306247237687SAl Viro if ((*opened & FILE_CREATED) || 3063496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 306477d660a8SMiklos Szeredi will_truncate = false; 3065d18e9008SMiklos Szeredi 306676ae2a5aSAl Viro audit_inode(nd->name, file->f_path.dentry, 0); 3067d18e9008SMiklos Szeredi goto opened; 3068d18e9008SMiklos Szeredi } 3069d18e9008SMiklos Szeredi 307047237687SAl Viro if (*opened & FILE_CREATED) { 30719b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3072ca344a89SAl Viro open_flag &= ~O_TRUNC; 307377d660a8SMiklos Szeredi will_truncate = false; 3074bcda7652SAl Viro acc_mode = MAY_OPEN; 3075896475d5SAl Viro path_to_nameidata(&path, nd); 3076e83db167SMiklos Szeredi goto finish_open_created; 3077fb1cc555SAl Viro } 3078fb1cc555SAl Viro 3079fb1cc555SAl Viro /* 30803134f37eSJeff Layton * create/update audit record if it already exists. 3081fb1cc555SAl Viro */ 3082896475d5SAl Viro if (d_is_positive(path.dentry)) 308376ae2a5aSAl Viro audit_inode(nd->name, path.dentry, 0); 3084fb1cc555SAl Viro 3085d18e9008SMiklos Szeredi /* 3086d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3087d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3088d18e9008SMiklos Szeredi * necessary...) 3089d18e9008SMiklos Szeredi */ 309064894cf8SAl Viro if (got_write) { 3091d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 309264894cf8SAl Viro got_write = false; 3093d18e9008SMiklos Szeredi } 3094d18e9008SMiklos Szeredi 3095deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3096deb106c6SAl Viro path_to_nameidata(&path, nd); 3097deb106c6SAl Viro return -EEXIST; 3098deb106c6SAl Viro } 3099fb1cc555SAl Viro 3100756daf26SNeilBrown error = follow_managed(&path, nd); 3101deb106c6SAl Viro if (unlikely(error < 0)) 3102deb106c6SAl Viro return error; 3103a3fbbde7SAl Viro 3104decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 310563afdfc7SDavid Howells inode = d_backing_inode(path.dentry); 3106254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3107deb106c6SAl Viro if (unlikely(d_is_negative(path.dentry))) { 3108896475d5SAl Viro path_to_nameidata(&path, nd); 3109deb106c6SAl Viro return -ENOENT; 311054c33e7fSMiklos Szeredi } 3111766c4cbfSAl Viro finish_lookup: 3112191d7f73SAl Viro if (nd->depth) 3113191d7f73SAl Viro put_link(nd); 3114181548c0SAl Viro error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW, 3115181548c0SAl Viro inode, seq); 3116deb106c6SAl Viro if (unlikely(error)) 3117d63ff28fSAl Viro return error; 3118fb1cc555SAl Viro 3119896475d5SAl Viro if (unlikely(d_is_symlink(path.dentry)) && !(open_flag & O_PATH)) { 3120896475d5SAl Viro path_to_nameidata(&path, nd); 3121deb106c6SAl Viro return -ELOOP; 3122a5cfe2d5SAl Viro } 3123a5cfe2d5SAl Viro 3124896475d5SAl Viro if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { 3125896475d5SAl Viro path_to_nameidata(&path, nd); 312616b1c1cdSMiklos Szeredi } else { 312716b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 3128896475d5SAl Viro save_parent.mnt = mntget(path.mnt); 3129896475d5SAl Viro nd->path.dentry = path.dentry; 313016b1c1cdSMiklos Szeredi 313116b1c1cdSMiklos Szeredi } 3132decf3400SMiklos Szeredi nd->inode = inode; 3133254cf582SAl Viro nd->seq = seq; 3134a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3135bc77daa7SAl Viro finish_open: 3136a3fbbde7SAl Viro error = complete_walk(nd); 313716b1c1cdSMiklos Szeredi if (error) { 313816b1c1cdSMiklos Szeredi path_put(&save_parent); 31392675a4ebSAl Viro return error; 314016b1c1cdSMiklos Szeredi } 314176ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 3142fb1cc555SAl Viro error = -EISDIR; 314344b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 31442675a4ebSAl Viro goto out; 3145af2f5542SMiklos Szeredi error = -ENOTDIR; 314644b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 31472675a4ebSAl Viro goto out; 31484bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 314977d660a8SMiklos Szeredi will_truncate = false; 31506c0d46c4SAl Viro 31510f9d1a10SAl Viro if (will_truncate) { 31520f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 31530f9d1a10SAl Viro if (error) 31542675a4ebSAl Viro goto out; 315564894cf8SAl Viro got_write = true; 31560f9d1a10SAl Viro } 3157e83db167SMiklos Szeredi finish_open_created: 3158bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3159ca344a89SAl Viro if (error) 31602675a4ebSAl Viro goto out; 31614aa7c634SMiklos Szeredi 31624aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 31634aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 31644aa7c634SMiklos Szeredi if (!error) { 31654aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 31664aa7c634SMiklos Szeredi } else { 316730d90494SAl Viro if (error == -EOPENSTALE) 3168f60dc3dbSMiklos Szeredi goto stale_open; 3169015c3bbcSMiklos Szeredi goto out; 3170f60dc3dbSMiklos Szeredi } 3171a8277b9bSMiklos Szeredi opened: 31722675a4ebSAl Viro error = open_check_o_direct(file); 3173015c3bbcSMiklos Szeredi if (error) 3174015c3bbcSMiklos Szeredi goto exit_fput; 31753034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3176aa4caadbSMiklos Szeredi if (error) 3177aa4caadbSMiklos Szeredi goto exit_fput; 3178aa4caadbSMiklos Szeredi 31790f9d1a10SAl Viro if (will_truncate) { 31802675a4ebSAl Viro error = handle_truncate(file); 3181aa4caadbSMiklos Szeredi if (error) 3182aa4caadbSMiklos Szeredi goto exit_fput; 31830f9d1a10SAl Viro } 3184ca344a89SAl Viro out: 318564894cf8SAl Viro if (got_write) 31860f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 318716b1c1cdSMiklos Szeredi path_put(&save_parent); 31882675a4ebSAl Viro return error; 3189fb1cc555SAl Viro 3190015c3bbcSMiklos Szeredi exit_fput: 31912675a4ebSAl Viro fput(file); 31922675a4ebSAl Viro goto out; 3193015c3bbcSMiklos Szeredi 3194f60dc3dbSMiklos Szeredi stale_open: 3195f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3196f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3197f60dc3dbSMiklos Szeredi goto out; 3198f60dc3dbSMiklos Szeredi 3199f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3200f60dc3dbSMiklos Szeredi path_put(&nd->path); 3201f60dc3dbSMiklos Szeredi nd->path = save_parent; 3202f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3203f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3204f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 320564894cf8SAl Viro if (got_write) { 3206f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 320764894cf8SAl Viro got_write = false; 3208f60dc3dbSMiklos Szeredi } 3209f60dc3dbSMiklos Szeredi retried = true; 3210f60dc3dbSMiklos Szeredi goto retry_lookup; 3211fb1cc555SAl Viro } 3212fb1cc555SAl Viro 3213c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 321460545d0dSAl Viro const struct open_flags *op, 321560545d0dSAl Viro struct file *file, int *opened) 321660545d0dSAl Viro { 321760545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 3218625b6d10SAl Viro struct dentry *child; 321960545d0dSAl Viro struct inode *dir; 3220625b6d10SAl Viro struct path path; 3221c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 322260545d0dSAl Viro if (unlikely(error)) 322360545d0dSAl Viro return error; 3224625b6d10SAl Viro error = mnt_want_write(path.mnt); 322560545d0dSAl Viro if (unlikely(error)) 322660545d0dSAl Viro goto out; 3227625b6d10SAl Viro dir = path.dentry->d_inode; 322860545d0dSAl Viro /* we want directory to be writable */ 3229625b6d10SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 323060545d0dSAl Viro if (error) 323160545d0dSAl Viro goto out2; 323260545d0dSAl Viro if (!dir->i_op->tmpfile) { 323360545d0dSAl Viro error = -EOPNOTSUPP; 323460545d0dSAl Viro goto out2; 323560545d0dSAl Viro } 3236625b6d10SAl Viro child = d_alloc(path.dentry, &name); 323760545d0dSAl Viro if (unlikely(!child)) { 323860545d0dSAl Viro error = -ENOMEM; 323960545d0dSAl Viro goto out2; 324060545d0dSAl Viro } 3241625b6d10SAl Viro dput(path.dentry); 3242625b6d10SAl Viro path.dentry = child; 3243625b6d10SAl Viro error = dir->i_op->tmpfile(dir, child, op->mode); 324460545d0dSAl Viro if (error) 324560545d0dSAl Viro goto out2; 3246c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 324769a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 3248625b6d10SAl Viro error = may_open(&path, MAY_OPEN, op->open_flag); 324960545d0dSAl Viro if (error) 325060545d0dSAl Viro goto out2; 3251625b6d10SAl Viro file->f_path.mnt = path.mnt; 3252625b6d10SAl Viro error = finish_open(file, child, NULL, opened); 325360545d0dSAl Viro if (error) 325460545d0dSAl Viro goto out2; 325560545d0dSAl Viro error = open_check_o_direct(file); 3256f4e0c30cSAl Viro if (error) { 325760545d0dSAl Viro fput(file); 3258f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3259f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3260f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3261f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3262f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3263f4e0c30cSAl Viro } 326460545d0dSAl Viro out2: 3265625b6d10SAl Viro mnt_drop_write(path.mnt); 326660545d0dSAl Viro out: 3267625b6d10SAl Viro path_put(&path); 326860545d0dSAl Viro return error; 326960545d0dSAl Viro } 327060545d0dSAl Viro 3271c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3272c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 32731da177e4SLinus Torvalds { 3274368ee9baSAl Viro const char *s; 327530d90494SAl Viro struct file *file; 327647237687SAl Viro int opened = 0; 327713aab428SAl Viro int error; 327831e6b01fSNick Piggin 327930d90494SAl Viro file = get_empty_filp(); 32801afc99beSAl Viro if (IS_ERR(file)) 32811afc99beSAl Viro return file; 328231e6b01fSNick Piggin 328330d90494SAl Viro file->f_flags = op->open_flag; 328431e6b01fSNick Piggin 3285bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 3286c8a53ee5SAl Viro error = do_tmpfile(nd, flags, op, file, &opened); 3287f15133dfSAl Viro goto out2; 328860545d0dSAl Viro } 328960545d0dSAl Viro 3290c8a53ee5SAl Viro s = path_init(nd, flags); 3291368ee9baSAl Viro if (IS_ERR(s)) { 3292368ee9baSAl Viro put_filp(file); 3293368ee9baSAl Viro return ERR_CAST(s); 3294368ee9baSAl Viro } 32953bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 329676ae2a5aSAl Viro (error = do_last(nd, file, op, &opened)) > 0) { 329773d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 32983bdba28bSAl Viro s = trailing_symlink(nd); 32993bdba28bSAl Viro if (IS_ERR(s)) { 33003bdba28bSAl Viro error = PTR_ERR(s); 33012675a4ebSAl Viro break; 3302806b681cSAl Viro } 33033bdba28bSAl Viro } 3304deb106c6SAl Viro terminate_walk(nd); 3305f15133dfSAl Viro out2: 33062675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 33072675a4ebSAl Viro BUG_ON(!error); 330830d90494SAl Viro put_filp(file); 3309015c3bbcSMiklos Szeredi } 33102675a4ebSAl Viro if (unlikely(error)) { 33112675a4ebSAl Viro if (error == -EOPENSTALE) { 33122675a4ebSAl Viro if (flags & LOOKUP_RCU) 33132675a4ebSAl Viro error = -ECHILD; 33142675a4ebSAl Viro else 33152675a4ebSAl Viro error = -ESTALE; 33162675a4ebSAl Viro } 33172675a4ebSAl Viro file = ERR_PTR(error); 33182675a4ebSAl Viro } 33192675a4ebSAl Viro return file; 3320de459215SKirill Korotaev } 33211da177e4SLinus Torvalds 3322669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3323f9652e10SAl Viro const struct open_flags *op) 332413aab428SAl Viro { 33259883d185SAl Viro struct nameidata nd; 3326f9652e10SAl Viro int flags = op->lookup_flags; 332713aab428SAl Viro struct file *filp; 332813aab428SAl Viro 33299883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3330c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 333113aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3332c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 333313aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3334c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 33359883d185SAl Viro restore_nameidata(); 333613aab428SAl Viro return filp; 333713aab428SAl Viro } 333813aab428SAl Viro 333973d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3340f9652e10SAl Viro const char *name, const struct open_flags *op) 334173d049a4SAl Viro { 33429883d185SAl Viro struct nameidata nd; 334373d049a4SAl Viro struct file *file; 334451689104SPaul Moore struct filename *filename; 3345f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 334673d049a4SAl Viro 334773d049a4SAl Viro nd.root.mnt = mnt; 334873d049a4SAl Viro nd.root.dentry = dentry; 334973d049a4SAl Viro 3350b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 335173d049a4SAl Viro return ERR_PTR(-ELOOP); 335273d049a4SAl Viro 335351689104SPaul Moore filename = getname_kernel(name); 335451689104SPaul Moore if (unlikely(IS_ERR(filename))) 335551689104SPaul Moore return ERR_CAST(filename); 335651689104SPaul Moore 33579883d185SAl Viro set_nameidata(&nd, -1, filename); 3358c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 335973d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3360c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 336173d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3362c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 33639883d185SAl Viro restore_nameidata(); 336451689104SPaul Moore putname(filename); 336573d049a4SAl Viro return file; 336673d049a4SAl Viro } 336773d049a4SAl Viro 3368fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 33691ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 33701da177e4SLinus Torvalds { 3371c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3372391172c4SAl Viro struct qstr last; 3373391172c4SAl Viro int type; 3374c30dabfeSJan Kara int err2; 33751ac12b4bSJeff Layton int error; 33761ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 33771ac12b4bSJeff Layton 33781ac12b4bSJeff Layton /* 33791ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 33801ac12b4bSJeff Layton * other flags passed in are ignored! 33811ac12b4bSJeff Layton */ 33821ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 33831ac12b4bSJeff Layton 33845c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 33855c31b6ceSAl Viro if (IS_ERR(name)) 33865c31b6ceSAl Viro return ERR_CAST(name); 33871da177e4SLinus Torvalds 3388c663e5d8SChristoph Hellwig /* 3389c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3390c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3391c663e5d8SChristoph Hellwig */ 33925c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3393ed75e95dSAl Viro goto out; 3394c663e5d8SChristoph Hellwig 3395c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3396391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3397c663e5d8SChristoph Hellwig /* 3398c663e5d8SChristoph Hellwig * Do the final lookup. 3399c663e5d8SChristoph Hellwig */ 3400391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 3401391172c4SAl Viro mutex_lock_nested(&path->dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3402391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 34031da177e4SLinus Torvalds if (IS_ERR(dentry)) 3404a8104a9fSAl Viro goto unlock; 3405c663e5d8SChristoph Hellwig 3406a8104a9fSAl Viro error = -EEXIST; 3407b18825a7SDavid Howells if (d_is_positive(dentry)) 3408a8104a9fSAl Viro goto fail; 3409b18825a7SDavid Howells 3410c663e5d8SChristoph Hellwig /* 3411c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3412c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3413c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3414c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3415c663e5d8SChristoph Hellwig */ 3416391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3417a8104a9fSAl Viro error = -ENOENT; 3418ed75e95dSAl Viro goto fail; 3419e9baf6e5SAl Viro } 3420c30dabfeSJan Kara if (unlikely(err2)) { 3421c30dabfeSJan Kara error = err2; 3422a8104a9fSAl Viro goto fail; 3423c30dabfeSJan Kara } 3424181c37b6SAl Viro putname(name); 3425e9baf6e5SAl Viro return dentry; 34261da177e4SLinus Torvalds fail: 3427a8104a9fSAl Viro dput(dentry); 3428a8104a9fSAl Viro dentry = ERR_PTR(error); 3429a8104a9fSAl Viro unlock: 3430391172c4SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3431c30dabfeSJan Kara if (!err2) 3432391172c4SAl Viro mnt_drop_write(path->mnt); 3433ed75e95dSAl Viro out: 3434391172c4SAl Viro path_put(path); 3435181c37b6SAl Viro putname(name); 3436ed75e95dSAl Viro return dentry; 3437dae6ad8fSAl Viro } 3438fa14a0b8SAl Viro 3439fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3440fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3441fa14a0b8SAl Viro { 3442181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3443181c37b6SAl Viro path, lookup_flags); 3444fa14a0b8SAl Viro } 3445dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3446dae6ad8fSAl Viro 3447921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3448921a1650SAl Viro { 3449921a1650SAl Viro dput(dentry); 3450921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3451a8104a9fSAl Viro mnt_drop_write(path->mnt); 3452921a1650SAl Viro path_put(path); 3453921a1650SAl Viro } 3454921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3455921a1650SAl Viro 3456520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 34571ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3458dae6ad8fSAl Viro { 3459181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3460dae6ad8fSAl Viro } 3461dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3462dae6ad8fSAl Viro 34631a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 34641da177e4SLinus Torvalds { 3465a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 34661da177e4SLinus Torvalds 34671da177e4SLinus Torvalds if (error) 34681da177e4SLinus Torvalds return error; 34691da177e4SLinus Torvalds 3470975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 34711da177e4SLinus Torvalds return -EPERM; 34721da177e4SLinus Torvalds 3473acfa4380SAl Viro if (!dir->i_op->mknod) 34741da177e4SLinus Torvalds return -EPERM; 34751da177e4SLinus Torvalds 347608ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 347708ce5f16SSerge E. Hallyn if (error) 347808ce5f16SSerge E. Hallyn return error; 347908ce5f16SSerge E. Hallyn 34801da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 34811da177e4SLinus Torvalds if (error) 34821da177e4SLinus Torvalds return error; 34831da177e4SLinus Torvalds 34841da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3485a74574aaSStephen Smalley if (!error) 3486f38aa942SAmy Griffis fsnotify_create(dir, dentry); 34871da177e4SLinus Torvalds return error; 34881da177e4SLinus Torvalds } 34894d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 34901da177e4SLinus Torvalds 3491f69aac00SAl Viro static int may_mknod(umode_t mode) 3492463c3197SDave Hansen { 3493463c3197SDave Hansen switch (mode & S_IFMT) { 3494463c3197SDave Hansen case S_IFREG: 3495463c3197SDave Hansen case S_IFCHR: 3496463c3197SDave Hansen case S_IFBLK: 3497463c3197SDave Hansen case S_IFIFO: 3498463c3197SDave Hansen case S_IFSOCK: 3499463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3500463c3197SDave Hansen return 0; 3501463c3197SDave Hansen case S_IFDIR: 3502463c3197SDave Hansen return -EPERM; 3503463c3197SDave Hansen default: 3504463c3197SDave Hansen return -EINVAL; 3505463c3197SDave Hansen } 3506463c3197SDave Hansen } 3507463c3197SDave Hansen 35088208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 35092e4d0924SHeiko Carstens unsigned, dev) 35101da177e4SLinus Torvalds { 35111da177e4SLinus Torvalds struct dentry *dentry; 3512dae6ad8fSAl Viro struct path path; 3513dae6ad8fSAl Viro int error; 3514972567f1SJeff Layton unsigned int lookup_flags = 0; 35151da177e4SLinus Torvalds 35168e4bfca1SAl Viro error = may_mknod(mode); 35178e4bfca1SAl Viro if (error) 35188e4bfca1SAl Viro return error; 3519972567f1SJeff Layton retry: 3520972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3521dae6ad8fSAl Viro if (IS_ERR(dentry)) 3522dae6ad8fSAl Viro return PTR_ERR(dentry); 35232ad94ae6SAl Viro 3524dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3525ce3b0f8dSAl Viro mode &= ~current_umask(); 3526dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3527be6d3e56SKentaro Takeda if (error) 3528a8104a9fSAl Viro goto out; 35291da177e4SLinus Torvalds switch (mode & S_IFMT) { 35301da177e4SLinus Torvalds case 0: case S_IFREG: 3531312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 35321da177e4SLinus Torvalds break; 35331da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3534dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 35351da177e4SLinus Torvalds new_decode_dev(dev)); 35361da177e4SLinus Torvalds break; 35371da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3538dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 35391da177e4SLinus Torvalds break; 35401da177e4SLinus Torvalds } 3541a8104a9fSAl Viro out: 3542921a1650SAl Viro done_path_create(&path, dentry); 3543972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3544972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3545972567f1SJeff Layton goto retry; 3546972567f1SJeff Layton } 35471da177e4SLinus Torvalds return error; 35481da177e4SLinus Torvalds } 35491da177e4SLinus Torvalds 35508208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 35515590ff0dSUlrich Drepper { 35525590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 35535590ff0dSUlrich Drepper } 35545590ff0dSUlrich Drepper 355518bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 35561da177e4SLinus Torvalds { 3557a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35588de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 35591da177e4SLinus Torvalds 35601da177e4SLinus Torvalds if (error) 35611da177e4SLinus Torvalds return error; 35621da177e4SLinus Torvalds 3563acfa4380SAl Viro if (!dir->i_op->mkdir) 35641da177e4SLinus Torvalds return -EPERM; 35651da177e4SLinus Torvalds 35661da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 35671da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 35681da177e4SLinus Torvalds if (error) 35691da177e4SLinus Torvalds return error; 35701da177e4SLinus Torvalds 35718de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 35728de52778SAl Viro return -EMLINK; 35738de52778SAl Viro 35741da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3575a74574aaSStephen Smalley if (!error) 3576f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 35771da177e4SLinus Torvalds return error; 35781da177e4SLinus Torvalds } 35794d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 35801da177e4SLinus Torvalds 3581a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 35821da177e4SLinus Torvalds { 35836902d925SDave Hansen struct dentry *dentry; 3584dae6ad8fSAl Viro struct path path; 3585dae6ad8fSAl Viro int error; 3586b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 35871da177e4SLinus Torvalds 3588b76d8b82SJeff Layton retry: 3589b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 35906902d925SDave Hansen if (IS_ERR(dentry)) 3591dae6ad8fSAl Viro return PTR_ERR(dentry); 35926902d925SDave Hansen 3593dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3594ce3b0f8dSAl Viro mode &= ~current_umask(); 3595dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3596a8104a9fSAl Viro if (!error) 3597dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3598921a1650SAl Viro done_path_create(&path, dentry); 3599b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3600b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3601b76d8b82SJeff Layton goto retry; 3602b76d8b82SJeff Layton } 36031da177e4SLinus Torvalds return error; 36041da177e4SLinus Torvalds } 36051da177e4SLinus Torvalds 3606a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 36075590ff0dSUlrich Drepper { 36085590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 36095590ff0dSUlrich Drepper } 36105590ff0dSUlrich Drepper 36111da177e4SLinus Torvalds /* 3612a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3613c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3614a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3615a71905f0SSage Weil * then we drop the dentry now. 36161da177e4SLinus Torvalds * 36171da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 36181da177e4SLinus Torvalds * do a 36191da177e4SLinus Torvalds * 36201da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 36211da177e4SLinus Torvalds * return -EBUSY; 36221da177e4SLinus Torvalds * 36231da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 36241da177e4SLinus Torvalds * that is still in use by something else.. 36251da177e4SLinus Torvalds */ 36261da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 36271da177e4SLinus Torvalds { 36281da177e4SLinus Torvalds shrink_dcache_parent(dentry); 36291da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 363098474236SWaiman Long if (dentry->d_lockref.count == 1) 36311da177e4SLinus Torvalds __d_drop(dentry); 36321da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 36331da177e4SLinus Torvalds } 36344d359507SAl Viro EXPORT_SYMBOL(dentry_unhash); 36351da177e4SLinus Torvalds 36361da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 36371da177e4SLinus Torvalds { 36381da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 36391da177e4SLinus Torvalds 36401da177e4SLinus Torvalds if (error) 36411da177e4SLinus Torvalds return error; 36421da177e4SLinus Torvalds 3643acfa4380SAl Viro if (!dir->i_op->rmdir) 36441da177e4SLinus Torvalds return -EPERM; 36451da177e4SLinus Torvalds 36461d2ef590SAl Viro dget(dentry); 36471b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3648912dbc15SSage Weil 36491da177e4SLinus Torvalds error = -EBUSY; 36507af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3651912dbc15SSage Weil goto out; 3652912dbc15SSage Weil 36531da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3654912dbc15SSage Weil if (error) 3655912dbc15SSage Weil goto out; 3656912dbc15SSage Weil 36573cebde24SSage Weil shrink_dcache_parent(dentry); 36581da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3659912dbc15SSage Weil if (error) 3660912dbc15SSage Weil goto out; 3661912dbc15SSage Weil 36621da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3663d83c49f3SAl Viro dont_mount(dentry); 36648ed936b5SEric W. Biederman detach_mounts(dentry); 36651da177e4SLinus Torvalds 3666912dbc15SSage Weil out: 3667912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 36681d2ef590SAl Viro dput(dentry); 3669912dbc15SSage Weil if (!error) 3670912dbc15SSage Weil d_delete(dentry); 36711da177e4SLinus Torvalds return error; 36721da177e4SLinus Torvalds } 36734d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 36741da177e4SLinus Torvalds 36755590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 36761da177e4SLinus Torvalds { 36771da177e4SLinus Torvalds int error = 0; 367891a27b2aSJeff Layton struct filename *name; 36791da177e4SLinus Torvalds struct dentry *dentry; 3680f5beed75SAl Viro struct path path; 3681f5beed75SAl Viro struct qstr last; 3682f5beed75SAl Viro int type; 3683c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3684c6ee9206SJeff Layton retry: 3685f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3686f5beed75SAl Viro &path, &last, &type, lookup_flags); 368791a27b2aSJeff Layton if (IS_ERR(name)) 368891a27b2aSJeff Layton return PTR_ERR(name); 36891da177e4SLinus Torvalds 3690f5beed75SAl Viro switch (type) { 36911da177e4SLinus Torvalds case LAST_DOTDOT: 36921da177e4SLinus Torvalds error = -ENOTEMPTY; 36931da177e4SLinus Torvalds goto exit1; 36941da177e4SLinus Torvalds case LAST_DOT: 36951da177e4SLinus Torvalds error = -EINVAL; 36961da177e4SLinus Torvalds goto exit1; 36971da177e4SLinus Torvalds case LAST_ROOT: 36981da177e4SLinus Torvalds error = -EBUSY; 36991da177e4SLinus Torvalds goto exit1; 37001da177e4SLinus Torvalds } 37010612d9fbSOGAWA Hirofumi 3702f5beed75SAl Viro error = mnt_want_write(path.mnt); 3703c30dabfeSJan Kara if (error) 3704c30dabfeSJan Kara goto exit1; 37050612d9fbSOGAWA Hirofumi 3706f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3707f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 37081da177e4SLinus Torvalds error = PTR_ERR(dentry); 37096902d925SDave Hansen if (IS_ERR(dentry)) 37106902d925SDave Hansen goto exit2; 3711e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3712e6bc45d6STheodore Ts'o error = -ENOENT; 3713e6bc45d6STheodore Ts'o goto exit3; 3714e6bc45d6STheodore Ts'o } 3715f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3716be6d3e56SKentaro Takeda if (error) 3717c30dabfeSJan Kara goto exit3; 3718f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 37190622753bSDave Hansen exit3: 37201da177e4SLinus Torvalds dput(dentry); 37216902d925SDave Hansen exit2: 3722f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 3723f5beed75SAl Viro mnt_drop_write(path.mnt); 37241da177e4SLinus Torvalds exit1: 3725f5beed75SAl Viro path_put(&path); 37261da177e4SLinus Torvalds putname(name); 3727c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3728c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3729c6ee9206SJeff Layton goto retry; 3730c6ee9206SJeff Layton } 37311da177e4SLinus Torvalds return error; 37321da177e4SLinus Torvalds } 37331da177e4SLinus Torvalds 37343cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 37355590ff0dSUlrich Drepper { 37365590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 37375590ff0dSUlrich Drepper } 37385590ff0dSUlrich Drepper 3739b21996e3SJ. Bruce Fields /** 3740b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3741b21996e3SJ. Bruce Fields * @dir: parent directory 3742b21996e3SJ. Bruce Fields * @dentry: victim 3743b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3744b21996e3SJ. Bruce Fields * 3745b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3746b21996e3SJ. Bruce Fields * 3747b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3748b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3749b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3750b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3751b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3752b21996e3SJ. Bruce Fields * 3753b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3754b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3755b21996e3SJ. Bruce Fields * to be NFS exported. 3756b21996e3SJ. Bruce Fields */ 3757b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 37581da177e4SLinus Torvalds { 37599accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 37601da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 37611da177e4SLinus Torvalds 37621da177e4SLinus Torvalds if (error) 37631da177e4SLinus Torvalds return error; 37641da177e4SLinus Torvalds 3765acfa4380SAl Viro if (!dir->i_op->unlink) 37661da177e4SLinus Torvalds return -EPERM; 37671da177e4SLinus Torvalds 37689accbb97SJ. Bruce Fields mutex_lock(&target->i_mutex); 37698ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 37701da177e4SLinus Torvalds error = -EBUSY; 37711da177e4SLinus Torvalds else { 37721da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3773bec1052eSAl Viro if (!error) { 37745a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 37755a14696cSJ. Bruce Fields if (error) 3776b21996e3SJ. Bruce Fields goto out; 37771da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 37788ed936b5SEric W. Biederman if (!error) { 3779d83c49f3SAl Viro dont_mount(dentry); 37808ed936b5SEric W. Biederman detach_mounts(dentry); 37818ed936b5SEric W. Biederman } 3782bec1052eSAl Viro } 37831da177e4SLinus Torvalds } 3784b21996e3SJ. Bruce Fields out: 37859accbb97SJ. Bruce Fields mutex_unlock(&target->i_mutex); 37861da177e4SLinus Torvalds 37871da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 37881da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 37899accbb97SJ. Bruce Fields fsnotify_link_count(target); 37901da177e4SLinus Torvalds d_delete(dentry); 37911da177e4SLinus Torvalds } 37920eeca283SRobert Love 37931da177e4SLinus Torvalds return error; 37941da177e4SLinus Torvalds } 37954d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 37961da177e4SLinus Torvalds 37971da177e4SLinus Torvalds /* 37981da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 37991b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 38001da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 38011da177e4SLinus Torvalds * while waiting on the I/O. 38021da177e4SLinus Torvalds */ 38035590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 38041da177e4SLinus Torvalds { 38052ad94ae6SAl Viro int error; 380691a27b2aSJeff Layton struct filename *name; 38071da177e4SLinus Torvalds struct dentry *dentry; 3808f5beed75SAl Viro struct path path; 3809f5beed75SAl Viro struct qstr last; 3810f5beed75SAl Viro int type; 38111da177e4SLinus Torvalds struct inode *inode = NULL; 3812b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 38135d18f813SJeff Layton unsigned int lookup_flags = 0; 38145d18f813SJeff Layton retry: 3815f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3816f5beed75SAl Viro &path, &last, &type, lookup_flags); 381791a27b2aSJeff Layton if (IS_ERR(name)) 381891a27b2aSJeff Layton return PTR_ERR(name); 38192ad94ae6SAl Viro 38201da177e4SLinus Torvalds error = -EISDIR; 3821f5beed75SAl Viro if (type != LAST_NORM) 38221da177e4SLinus Torvalds goto exit1; 38230612d9fbSOGAWA Hirofumi 3824f5beed75SAl Viro error = mnt_want_write(path.mnt); 3825c30dabfeSJan Kara if (error) 3826c30dabfeSJan Kara goto exit1; 3827b21996e3SJ. Bruce Fields retry_deleg: 3828f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3829f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38301da177e4SLinus Torvalds error = PTR_ERR(dentry); 38311da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 38321da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3833f5beed75SAl Viro if (last.name[last.len]) 383450338b88STörök Edwin goto slashes; 38351da177e4SLinus Torvalds inode = dentry->d_inode; 3836b18825a7SDavid Howells if (d_is_negative(dentry)) 3837e6bc45d6STheodore Ts'o goto slashes; 38387de9c6eeSAl Viro ihold(inode); 3839f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3840be6d3e56SKentaro Takeda if (error) 3841c30dabfeSJan Kara goto exit2; 3842f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 38431da177e4SLinus Torvalds exit2: 38441da177e4SLinus Torvalds dput(dentry); 38451da177e4SLinus Torvalds } 3846f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 38471da177e4SLinus Torvalds if (inode) 38481da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3849b21996e3SJ. Bruce Fields inode = NULL; 3850b21996e3SJ. Bruce Fields if (delegated_inode) { 38515a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3852b21996e3SJ. Bruce Fields if (!error) 3853b21996e3SJ. Bruce Fields goto retry_deleg; 3854b21996e3SJ. Bruce Fields } 3855f5beed75SAl Viro mnt_drop_write(path.mnt); 38561da177e4SLinus Torvalds exit1: 3857f5beed75SAl Viro path_put(&path); 38581da177e4SLinus Torvalds putname(name); 38595d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 38605d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 38615d18f813SJeff Layton inode = NULL; 38625d18f813SJeff Layton goto retry; 38635d18f813SJeff Layton } 38641da177e4SLinus Torvalds return error; 38651da177e4SLinus Torvalds 38661da177e4SLinus Torvalds slashes: 3867b18825a7SDavid Howells if (d_is_negative(dentry)) 3868b18825a7SDavid Howells error = -ENOENT; 386944b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3870b18825a7SDavid Howells error = -EISDIR; 3871b18825a7SDavid Howells else 3872b18825a7SDavid Howells error = -ENOTDIR; 38731da177e4SLinus Torvalds goto exit2; 38741da177e4SLinus Torvalds } 38751da177e4SLinus Torvalds 38762e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 38775590ff0dSUlrich Drepper { 38785590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 38795590ff0dSUlrich Drepper return -EINVAL; 38805590ff0dSUlrich Drepper 38815590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 38825590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 38835590ff0dSUlrich Drepper 38845590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 38855590ff0dSUlrich Drepper } 38865590ff0dSUlrich Drepper 38873480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 38885590ff0dSUlrich Drepper { 38895590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 38905590ff0dSUlrich Drepper } 38915590ff0dSUlrich Drepper 3892db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 38931da177e4SLinus Torvalds { 3894a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 38951da177e4SLinus Torvalds 38961da177e4SLinus Torvalds if (error) 38971da177e4SLinus Torvalds return error; 38981da177e4SLinus Torvalds 3899acfa4380SAl Viro if (!dir->i_op->symlink) 39001da177e4SLinus Torvalds return -EPERM; 39011da177e4SLinus Torvalds 39021da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 39031da177e4SLinus Torvalds if (error) 39041da177e4SLinus Torvalds return error; 39051da177e4SLinus Torvalds 39061da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3907a74574aaSStephen Smalley if (!error) 3908f38aa942SAmy Griffis fsnotify_create(dir, dentry); 39091da177e4SLinus Torvalds return error; 39101da177e4SLinus Torvalds } 39114d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 39121da177e4SLinus Torvalds 39132e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 39142e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 39151da177e4SLinus Torvalds { 39162ad94ae6SAl Viro int error; 391791a27b2aSJeff Layton struct filename *from; 39186902d925SDave Hansen struct dentry *dentry; 3919dae6ad8fSAl Viro struct path path; 3920f46d3567SJeff Layton unsigned int lookup_flags = 0; 39211da177e4SLinus Torvalds 39221da177e4SLinus Torvalds from = getname(oldname); 39231da177e4SLinus Torvalds if (IS_ERR(from)) 39241da177e4SLinus Torvalds return PTR_ERR(from); 3925f46d3567SJeff Layton retry: 3926f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 39271da177e4SLinus Torvalds error = PTR_ERR(dentry); 39286902d925SDave Hansen if (IS_ERR(dentry)) 3929dae6ad8fSAl Viro goto out_putname; 39306902d925SDave Hansen 393191a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3932a8104a9fSAl Viro if (!error) 393391a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3934921a1650SAl Viro done_path_create(&path, dentry); 3935f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 3936f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 3937f46d3567SJeff Layton goto retry; 3938f46d3567SJeff Layton } 39396902d925SDave Hansen out_putname: 39401da177e4SLinus Torvalds putname(from); 39411da177e4SLinus Torvalds return error; 39421da177e4SLinus Torvalds } 39431da177e4SLinus Torvalds 39443480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 39455590ff0dSUlrich Drepper { 39465590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 39475590ff0dSUlrich Drepper } 39485590ff0dSUlrich Drepper 3949146a8595SJ. Bruce Fields /** 3950146a8595SJ. Bruce Fields * vfs_link - create a new link 3951146a8595SJ. Bruce Fields * @old_dentry: object to be linked 3952146a8595SJ. Bruce Fields * @dir: new parent 3953146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 3954146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 3955146a8595SJ. Bruce Fields * 3956146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 3957146a8595SJ. Bruce Fields * 3958146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 3959146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 3960146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 3961146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 3962146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 3963146a8595SJ. Bruce Fields * 3964146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3965146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3966146a8595SJ. Bruce Fields * to be NFS exported. 3967146a8595SJ. Bruce Fields */ 3968146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 39691da177e4SLinus Torvalds { 39701da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 39718de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 39721da177e4SLinus Torvalds int error; 39731da177e4SLinus Torvalds 39741da177e4SLinus Torvalds if (!inode) 39751da177e4SLinus Torvalds return -ENOENT; 39761da177e4SLinus Torvalds 3977a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 39781da177e4SLinus Torvalds if (error) 39791da177e4SLinus Torvalds return error; 39801da177e4SLinus Torvalds 39811da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 39821da177e4SLinus Torvalds return -EXDEV; 39831da177e4SLinus Torvalds 39841da177e4SLinus Torvalds /* 39851da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 39861da177e4SLinus Torvalds */ 39871da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 39881da177e4SLinus Torvalds return -EPERM; 3989acfa4380SAl Viro if (!dir->i_op->link) 39901da177e4SLinus Torvalds return -EPERM; 39917e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 39921da177e4SLinus Torvalds return -EPERM; 39931da177e4SLinus Torvalds 39941da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 39951da177e4SLinus Torvalds if (error) 39961da177e4SLinus Torvalds return error; 39971da177e4SLinus Torvalds 39987e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 3999aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4000f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4001aae8a97dSAneesh Kumar K.V error = -ENOENT; 40028de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 40038de52778SAl Viro error = -EMLINK; 4004146a8595SJ. Bruce Fields else { 4005146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4006146a8595SJ. Bruce Fields if (!error) 40071da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4008146a8595SJ. Bruce Fields } 4009f4e0c30cSAl Viro 4010f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4011f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4012f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4013f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4014f4e0c30cSAl Viro } 40157e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 4016e31e14ecSStephen Smalley if (!error) 40177e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 40181da177e4SLinus Torvalds return error; 40191da177e4SLinus Torvalds } 40204d359507SAl Viro EXPORT_SYMBOL(vfs_link); 40211da177e4SLinus Torvalds 40221da177e4SLinus Torvalds /* 40231da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 40241da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 40251da177e4SLinus Torvalds * newname. --KAB 40261da177e4SLinus Torvalds * 40271da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 40281da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 40291da177e4SLinus Torvalds * and other special files. --ADM 40301da177e4SLinus Torvalds */ 40312e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 40322e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 40331da177e4SLinus Torvalds { 40341da177e4SLinus Torvalds struct dentry *new_dentry; 4035dae6ad8fSAl Viro struct path old_path, new_path; 4036146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 403711a7b371SAneesh Kumar K.V int how = 0; 40381da177e4SLinus Torvalds int error; 40391da177e4SLinus Torvalds 404011a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4041c04030e1SUlrich Drepper return -EINVAL; 404211a7b371SAneesh Kumar K.V /* 4043f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4044f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4045f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 404611a7b371SAneesh Kumar K.V */ 4047f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4048f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4049f0cc6ffbSLinus Torvalds return -ENOENT; 405011a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4051f0cc6ffbSLinus Torvalds } 4052c04030e1SUlrich Drepper 405311a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 405411a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4055442e31caSJeff Layton retry: 405611a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 40571da177e4SLinus Torvalds if (error) 40582ad94ae6SAl Viro return error; 40592ad94ae6SAl Viro 4060442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4061442e31caSJeff Layton (how & LOOKUP_REVAL)); 40621da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 40636902d925SDave Hansen if (IS_ERR(new_dentry)) 4064dae6ad8fSAl Viro goto out; 4065dae6ad8fSAl Viro 4066dae6ad8fSAl Viro error = -EXDEV; 4067dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4068dae6ad8fSAl Viro goto out_dput; 4069800179c9SKees Cook error = may_linkat(&old_path); 4070800179c9SKees Cook if (unlikely(error)) 4071800179c9SKees Cook goto out_dput; 4072dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4073be6d3e56SKentaro Takeda if (error) 4074a8104a9fSAl Viro goto out_dput; 4075146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 407675c3f29dSDave Hansen out_dput: 4077921a1650SAl Viro done_path_create(&new_path, new_dentry); 4078146a8595SJ. Bruce Fields if (delegated_inode) { 4079146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4080d22e6338SOleg Drokin if (!error) { 4081d22e6338SOleg Drokin path_put(&old_path); 4082146a8595SJ. Bruce Fields goto retry; 4083146a8595SJ. Bruce Fields } 4084d22e6338SOleg Drokin } 4085442e31caSJeff Layton if (retry_estale(error, how)) { 4086d22e6338SOleg Drokin path_put(&old_path); 4087442e31caSJeff Layton how |= LOOKUP_REVAL; 4088442e31caSJeff Layton goto retry; 4089442e31caSJeff Layton } 40901da177e4SLinus Torvalds out: 40912d8f3038SAl Viro path_put(&old_path); 40921da177e4SLinus Torvalds 40931da177e4SLinus Torvalds return error; 40941da177e4SLinus Torvalds } 40951da177e4SLinus Torvalds 40963480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 40975590ff0dSUlrich Drepper { 4098c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 40995590ff0dSUlrich Drepper } 41005590ff0dSUlrich Drepper 4101bc27027aSMiklos Szeredi /** 4102bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4103bc27027aSMiklos Szeredi * @old_dir: parent of source 4104bc27027aSMiklos Szeredi * @old_dentry: source 4105bc27027aSMiklos Szeredi * @new_dir: parent of destination 4106bc27027aSMiklos Szeredi * @new_dentry: destination 4107bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4108520c8b16SMiklos Szeredi * @flags: rename flags 4109bc27027aSMiklos Szeredi * 4110bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4111bc27027aSMiklos Szeredi * 4112bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4113bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4114bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4115bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4116bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4117bc27027aSMiklos Szeredi * so. 4118bc27027aSMiklos Szeredi * 4119bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4120bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4121bc27027aSMiklos Szeredi * to be NFS exported. 4122bc27027aSMiklos Szeredi * 41231da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 41241da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 41251da177e4SLinus Torvalds * Problems: 4126d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 41271da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 41281da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4129a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 41301da177e4SLinus Torvalds * story. 41316cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 41326cedba89SJ. Bruce Fields * and source (if it is not a directory). 41331b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 41341da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 41351da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4136a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 41371da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 41381da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 41391da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4140a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 41411da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 41421da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 41431da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4144e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 41451b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 41461da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4147c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 41481da177e4SLinus Torvalds * locking]. 41491da177e4SLinus Torvalds */ 41501da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 41518e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4152520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 41531da177e4SLinus Torvalds { 41541da177e4SLinus Torvalds int error; 4155bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 415659b0df21SEric Paris const unsigned char *old_name; 4157bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4158bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4159da1ce067SMiklos Szeredi bool new_is_dir = false; 4160da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 41611da177e4SLinus Torvalds 4162bc27027aSMiklos Szeredi if (source == target) 41631da177e4SLinus Torvalds return 0; 41641da177e4SLinus Torvalds 41651da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 41661da177e4SLinus Torvalds if (error) 41671da177e4SLinus Torvalds return error; 41681da177e4SLinus Torvalds 4169da1ce067SMiklos Szeredi if (!target) { 4170a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4171da1ce067SMiklos Szeredi } else { 4172da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4173da1ce067SMiklos Szeredi 4174da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 41751da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4176da1ce067SMiklos Szeredi else 4177da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4178da1ce067SMiklos Szeredi } 41791da177e4SLinus Torvalds if (error) 41801da177e4SLinus Torvalds return error; 41811da177e4SLinus Torvalds 41827177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 41831da177e4SLinus Torvalds return -EPERM; 41841da177e4SLinus Torvalds 4185520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4186520c8b16SMiklos Szeredi return -EINVAL; 4187520c8b16SMiklos Szeredi 4188bc27027aSMiklos Szeredi /* 4189bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4190bc27027aSMiklos Szeredi * we'll need to flip '..'. 4191bc27027aSMiklos Szeredi */ 4192da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4193da1ce067SMiklos Szeredi if (is_dir) { 4194bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4195bc27027aSMiklos Szeredi if (error) 4196bc27027aSMiklos Szeredi return error; 4197bc27027aSMiklos Szeredi } 4198da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4199da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4200da1ce067SMiklos Szeredi if (error) 4201da1ce067SMiklos Szeredi return error; 4202da1ce067SMiklos Szeredi } 4203da1ce067SMiklos Szeredi } 42040eeca283SRobert Love 42050b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 42060b3974ebSMiklos Szeredi flags); 4207bc27027aSMiklos Szeredi if (error) 4208bc27027aSMiklos Szeredi return error; 4209bc27027aSMiklos Szeredi 4210bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4211bc27027aSMiklos Szeredi dget(new_dentry); 4212da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4213bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4214bc27027aSMiklos Szeredi else if (target) 4215bc27027aSMiklos Szeredi mutex_lock(&target->i_mutex); 4216bc27027aSMiklos Szeredi 4217bc27027aSMiklos Szeredi error = -EBUSY; 42187af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4219bc27027aSMiklos Szeredi goto out; 4220bc27027aSMiklos Szeredi 4221da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4222bc27027aSMiklos Szeredi error = -EMLINK; 4223da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4224bc27027aSMiklos Szeredi goto out; 4225da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4226da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4227da1ce067SMiklos Szeredi goto out; 4228da1ce067SMiklos Szeredi } 4229da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4230bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4231da1ce067SMiklos Szeredi if (!is_dir) { 4232bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4233bc27027aSMiklos Szeredi if (error) 4234bc27027aSMiklos Szeredi goto out; 4235da1ce067SMiklos Szeredi } 4236da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4237bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4238bc27027aSMiklos Szeredi if (error) 4239bc27027aSMiklos Szeredi goto out; 4240bc27027aSMiklos Szeredi } 42417177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4242520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4243520c8b16SMiklos Szeredi new_dir, new_dentry); 4244520c8b16SMiklos Szeredi } else { 42457177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4246520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4247520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4248520c8b16SMiklos Szeredi } 4249bc27027aSMiklos Szeredi if (error) 4250bc27027aSMiklos Szeredi goto out; 4251bc27027aSMiklos Szeredi 4252da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 42531da177e4SLinus Torvalds if (is_dir) 4254bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4255bc27027aSMiklos Szeredi dont_mount(new_dentry); 42568ed936b5SEric W. Biederman detach_mounts(new_dentry); 4257bc27027aSMiklos Szeredi } 4258da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4259da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4260bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4261da1ce067SMiklos Szeredi else 4262da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4263da1ce067SMiklos Szeredi } 4264bc27027aSMiklos Szeredi out: 4265da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4266bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4267bc27027aSMiklos Szeredi else if (target) 4268bc27027aSMiklos Szeredi mutex_unlock(&target->i_mutex); 4269bc27027aSMiklos Szeredi dput(new_dentry); 4270da1ce067SMiklos Szeredi if (!error) { 4271123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4272da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4273da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4274da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4275da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4276da1ce067SMiklos Szeredi } 4277da1ce067SMiklos Szeredi } 42780eeca283SRobert Love fsnotify_oldname_free(old_name); 42790eeca283SRobert Love 42801da177e4SLinus Torvalds return error; 42811da177e4SLinus Torvalds } 42824d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 42831da177e4SLinus Torvalds 4284520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4285520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 42861da177e4SLinus Torvalds { 42871da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 42881da177e4SLinus Torvalds struct dentry *trap; 4289f5beed75SAl Viro struct path old_path, new_path; 4290f5beed75SAl Viro struct qstr old_last, new_last; 4291f5beed75SAl Viro int old_type, new_type; 42928e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 429391a27b2aSJeff Layton struct filename *from; 429491a27b2aSJeff Layton struct filename *to; 4295f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4296c6a94284SJeff Layton bool should_retry = false; 42972ad94ae6SAl Viro int error; 4298520c8b16SMiklos Szeredi 42990d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4300da1ce067SMiklos Szeredi return -EINVAL; 4301da1ce067SMiklos Szeredi 43020d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 43030d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4304520c8b16SMiklos Szeredi return -EINVAL; 4305520c8b16SMiklos Szeredi 43060d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 43070d7a8555SMiklos Szeredi return -EPERM; 43080d7a8555SMiklos Szeredi 4309f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4310f5beed75SAl Viro target_flags = 0; 4311f5beed75SAl Viro 4312c6a94284SJeff Layton retry: 4313f5beed75SAl Viro from = user_path_parent(olddfd, oldname, 4314f5beed75SAl Viro &old_path, &old_last, &old_type, lookup_flags); 431591a27b2aSJeff Layton if (IS_ERR(from)) { 431691a27b2aSJeff Layton error = PTR_ERR(from); 43171da177e4SLinus Torvalds goto exit; 431891a27b2aSJeff Layton } 43191da177e4SLinus Torvalds 4320f5beed75SAl Viro to = user_path_parent(newdfd, newname, 4321f5beed75SAl Viro &new_path, &new_last, &new_type, lookup_flags); 432291a27b2aSJeff Layton if (IS_ERR(to)) { 432391a27b2aSJeff Layton error = PTR_ERR(to); 43241da177e4SLinus Torvalds goto exit1; 432591a27b2aSJeff Layton } 43261da177e4SLinus Torvalds 43271da177e4SLinus Torvalds error = -EXDEV; 4328f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 43291da177e4SLinus Torvalds goto exit2; 43301da177e4SLinus Torvalds 43311da177e4SLinus Torvalds error = -EBUSY; 4332f5beed75SAl Viro if (old_type != LAST_NORM) 43331da177e4SLinus Torvalds goto exit2; 43341da177e4SLinus Torvalds 43350a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 43360a7c3937SMiklos Szeredi error = -EEXIST; 4337f5beed75SAl Viro if (new_type != LAST_NORM) 43381da177e4SLinus Torvalds goto exit2; 43391da177e4SLinus Torvalds 4340f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4341c30dabfeSJan Kara if (error) 4342c30dabfeSJan Kara goto exit2; 4343c30dabfeSJan Kara 43448e6d782cSJ. Bruce Fields retry_deleg: 4345f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 43461da177e4SLinus Torvalds 4347f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 43481da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 43491da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 43501da177e4SLinus Torvalds goto exit3; 43511da177e4SLinus Torvalds /* source must exist */ 43521da177e4SLinus Torvalds error = -ENOENT; 4353b18825a7SDavid Howells if (d_is_negative(old_dentry)) 43541da177e4SLinus Torvalds goto exit4; 4355f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 43561da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 43571da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 43581da177e4SLinus Torvalds goto exit4; 43590a7c3937SMiklos Szeredi error = -EEXIST; 43600a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 43610a7c3937SMiklos Szeredi goto exit5; 4362da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4363da1ce067SMiklos Szeredi error = -ENOENT; 4364da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4365da1ce067SMiklos Szeredi goto exit5; 4366da1ce067SMiklos Szeredi 4367da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4368da1ce067SMiklos Szeredi error = -ENOTDIR; 4369f5beed75SAl Viro if (new_last.name[new_last.len]) 4370da1ce067SMiklos Szeredi goto exit5; 4371da1ce067SMiklos Szeredi } 4372da1ce067SMiklos Szeredi } 43730a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 43740a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 43750a7c3937SMiklos Szeredi error = -ENOTDIR; 4376f5beed75SAl Viro if (old_last.name[old_last.len]) 43770a7c3937SMiklos Szeredi goto exit5; 4378f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 43790a7c3937SMiklos Szeredi goto exit5; 43800a7c3937SMiklos Szeredi } 43810a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 43820a7c3937SMiklos Szeredi error = -EINVAL; 43830a7c3937SMiklos Szeredi if (old_dentry == trap) 43840a7c3937SMiklos Szeredi goto exit5; 43851da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4386da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43871da177e4SLinus Torvalds error = -ENOTEMPTY; 43881da177e4SLinus Torvalds if (new_dentry == trap) 43891da177e4SLinus Torvalds goto exit5; 43901da177e4SLinus Torvalds 4391f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4392f5beed75SAl Viro &new_path, new_dentry, flags); 4393be6d3e56SKentaro Takeda if (error) 4394c30dabfeSJan Kara goto exit5; 4395f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4396f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4397520c8b16SMiklos Szeredi &delegated_inode, flags); 43981da177e4SLinus Torvalds exit5: 43991da177e4SLinus Torvalds dput(new_dentry); 44001da177e4SLinus Torvalds exit4: 44011da177e4SLinus Torvalds dput(old_dentry); 44021da177e4SLinus Torvalds exit3: 4403f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 44048e6d782cSJ. Bruce Fields if (delegated_inode) { 44058e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 44068e6d782cSJ. Bruce Fields if (!error) 44078e6d782cSJ. Bruce Fields goto retry_deleg; 44088e6d782cSJ. Bruce Fields } 4409f5beed75SAl Viro mnt_drop_write(old_path.mnt); 44101da177e4SLinus Torvalds exit2: 4411c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4412c6a94284SJeff Layton should_retry = true; 4413f5beed75SAl Viro path_put(&new_path); 44142ad94ae6SAl Viro putname(to); 44151da177e4SLinus Torvalds exit1: 4416f5beed75SAl Viro path_put(&old_path); 44171da177e4SLinus Torvalds putname(from); 4418c6a94284SJeff Layton if (should_retry) { 4419c6a94284SJeff Layton should_retry = false; 4420c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4421c6a94284SJeff Layton goto retry; 4422c6a94284SJeff Layton } 44232ad94ae6SAl Viro exit: 44241da177e4SLinus Torvalds return error; 44251da177e4SLinus Torvalds } 44261da177e4SLinus Torvalds 4427520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4428520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4429520c8b16SMiklos Szeredi { 4430520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4431520c8b16SMiklos Szeredi } 4432520c8b16SMiklos Szeredi 4433a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 44345590ff0dSUlrich Drepper { 4435520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 44365590ff0dSUlrich Drepper } 44375590ff0dSUlrich Drepper 4438787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4439787fb6bcSMiklos Szeredi { 4440787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4441787fb6bcSMiklos Szeredi if (error) 4442787fb6bcSMiklos Szeredi return error; 4443787fb6bcSMiklos Szeredi 4444787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4445787fb6bcSMiklos Szeredi return -EPERM; 4446787fb6bcSMiklos Szeredi 4447787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4448787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4449787fb6bcSMiklos Szeredi } 4450787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4451787fb6bcSMiklos Szeredi 44525d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 44531da177e4SLinus Torvalds { 44545d826c84SAl Viro int len = PTR_ERR(link); 44551da177e4SLinus Torvalds if (IS_ERR(link)) 44561da177e4SLinus Torvalds goto out; 44571da177e4SLinus Torvalds 44581da177e4SLinus Torvalds len = strlen(link); 44591da177e4SLinus Torvalds if (len > (unsigned) buflen) 44601da177e4SLinus Torvalds len = buflen; 44611da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 44621da177e4SLinus Torvalds len = -EFAULT; 44631da177e4SLinus Torvalds out: 44641da177e4SLinus Torvalds return len; 44651da177e4SLinus Torvalds } 44665d826c84SAl Viro EXPORT_SYMBOL(readlink_copy); 44671da177e4SLinus Torvalds 44681da177e4SLinus Torvalds /* 44691da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 44701da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 44711da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 44721da177e4SLinus Torvalds */ 44731da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44741da177e4SLinus Torvalds { 4475cc314eefSLinus Torvalds void *cookie; 44765f2c4179SAl Viro struct inode *inode = d_inode(dentry); 44775f2c4179SAl Viro const char *link = inode->i_link; 4478694a1764SMarcin Slusarz int res; 4479cc314eefSLinus Torvalds 4480d4dee48bSAl Viro if (!link) { 44815f2c4179SAl Viro link = inode->i_op->follow_link(dentry, &cookie); 4482680baacbSAl Viro if (IS_ERR(link)) 4483680baacbSAl Viro return PTR_ERR(link); 4484d4dee48bSAl Viro } 4485680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 44865f2c4179SAl Viro if (inode->i_op->put_link) 44875f2c4179SAl Viro inode->i_op->put_link(inode, cookie); 4488694a1764SMarcin Slusarz return res; 44891da177e4SLinus Torvalds } 44904d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 44911da177e4SLinus Torvalds 44921da177e4SLinus Torvalds /* get the link contents into pagecache */ 44931da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 44941da177e4SLinus Torvalds { 4495ebd09abbSDuane Griffin char *kaddr; 44961da177e4SLinus Torvalds struct page *page; 44971da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 4498090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 44991da177e4SLinus Torvalds if (IS_ERR(page)) 45006fe6900eSNick Piggin return (char*)page; 45011da177e4SLinus Torvalds *ppage = page; 4502ebd09abbSDuane Griffin kaddr = kmap(page); 4503ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 4504ebd09abbSDuane Griffin return kaddr; 45051da177e4SLinus Torvalds } 45061da177e4SLinus Torvalds 45071da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 45081da177e4SLinus Torvalds { 45091da177e4SLinus Torvalds struct page *page = NULL; 45105d826c84SAl Viro int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); 45111da177e4SLinus Torvalds if (page) { 45121da177e4SLinus Torvalds kunmap(page); 45131da177e4SLinus Torvalds page_cache_release(page); 45141da177e4SLinus Torvalds } 45151da177e4SLinus Torvalds return res; 45161da177e4SLinus Torvalds } 45174d359507SAl Viro EXPORT_SYMBOL(page_readlink); 45181da177e4SLinus Torvalds 45196e77137bSAl Viro const char *page_follow_link_light(struct dentry *dentry, void **cookie) 45201da177e4SLinus Torvalds { 4521cc314eefSLinus Torvalds struct page *page = NULL; 4522680baacbSAl Viro char *res = page_getlink(dentry, &page); 4523680baacbSAl Viro if (!IS_ERR(res)) 4524680baacbSAl Viro *cookie = page; 4525680baacbSAl Viro return res; 45261da177e4SLinus Torvalds } 45274d359507SAl Viro EXPORT_SYMBOL(page_follow_link_light); 45281da177e4SLinus Torvalds 45295f2c4179SAl Viro void page_put_link(struct inode *unused, void *cookie) 45301da177e4SLinus Torvalds { 4531cc314eefSLinus Torvalds struct page *page = cookie; 45321da177e4SLinus Torvalds kunmap(page); 45331da177e4SLinus Torvalds page_cache_release(page); 45341da177e4SLinus Torvalds } 45354d359507SAl Viro EXPORT_SYMBOL(page_put_link); 45361da177e4SLinus Torvalds 453754566b2cSNick Piggin /* 453854566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 453954566b2cSNick Piggin */ 454054566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 45411da177e4SLinus Torvalds { 45421da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 45430adb25d2SKirill Korotaev struct page *page; 4544afddba49SNick Piggin void *fsdata; 4545beb497abSDmitriy Monakhov int err; 45461da177e4SLinus Torvalds char *kaddr; 454754566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 454854566b2cSNick Piggin if (nofs) 454954566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 45501da177e4SLinus Torvalds 45517e53cac4SNeilBrown retry: 4552afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 455354566b2cSNick Piggin flags, &page, &fsdata); 45541da177e4SLinus Torvalds if (err) 4555afddba49SNick Piggin goto fail; 4556afddba49SNick Piggin 4557e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 45581da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 4559e8e3c3d6SCong Wang kunmap_atomic(kaddr); 4560afddba49SNick Piggin 4561afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4562afddba49SNick Piggin page, fsdata); 45631da177e4SLinus Torvalds if (err < 0) 45641da177e4SLinus Torvalds goto fail; 4565afddba49SNick Piggin if (err < len-1) 4566afddba49SNick Piggin goto retry; 4567afddba49SNick Piggin 45681da177e4SLinus Torvalds mark_inode_dirty(inode); 45691da177e4SLinus Torvalds return 0; 45701da177e4SLinus Torvalds fail: 45711da177e4SLinus Torvalds return err; 45721da177e4SLinus Torvalds } 45734d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 45741da177e4SLinus Torvalds 45750adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 45760adb25d2SKirill Korotaev { 45770adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 457854566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 45790adb25d2SKirill Korotaev } 45804d359507SAl Viro EXPORT_SYMBOL(page_symlink); 45810adb25d2SKirill Korotaev 458292e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 45831da177e4SLinus Torvalds .readlink = generic_readlink, 45841da177e4SLinus Torvalds .follow_link = page_follow_link_light, 45851da177e4SLinus Torvalds .put_link = page_put_link, 45861da177e4SLinus Torvalds }; 45871da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4588