11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namei.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Some corrections by tytso. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 121da177e4SLinus Torvalds * lookup logic. 131da177e4SLinus Torvalds */ 141da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 151da177e4SLinus Torvalds */ 161da177e4SLinus Torvalds 171da177e4SLinus Torvalds #include <linux/init.h> 18630d9c47SPaul Gortmaker #include <linux/export.h> 1944696908SDavid S. Miller #include <linux/kernel.h> 201da177e4SLinus Torvalds #include <linux/slab.h> 211da177e4SLinus Torvalds #include <linux/fs.h> 221da177e4SLinus Torvalds #include <linux/namei.h> 231da177e4SLinus Torvalds #include <linux/pagemap.h> 240eeca283SRobert Love #include <linux/fsnotify.h> 251da177e4SLinus Torvalds #include <linux/personality.h> 261da177e4SLinus Torvalds #include <linux/security.h> 276146f0d5SMimi Zohar #include <linux/ima.h> 281da177e4SLinus Torvalds #include <linux/syscalls.h> 291da177e4SLinus Torvalds #include <linux/mount.h> 301da177e4SLinus Torvalds #include <linux/audit.h> 3116f7e0feSRandy Dunlap #include <linux/capability.h> 32834f2a4aSTrond Myklebust #include <linux/file.h> 335590ff0dSUlrich Drepper #include <linux/fcntl.h> 3408ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 355ad4e53bSAl Viro #include <linux/fs_struct.h> 36e77819e5SLinus Torvalds #include <linux/posix_acl.h> 3799d263d4SLinus Torvalds #include <linux/hash.h> 381da177e4SLinus Torvalds #include <asm/uaccess.h> 391da177e4SLinus Torvalds 40e81e3f4dSEric Paris #include "internal.h" 41c7105365SAl Viro #include "mount.h" 42e81e3f4dSEric Paris 431da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 441da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 451da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 461da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 471da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 481da177e4SLinus Torvalds * 491da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 501da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 511da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 521da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 531da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 541da177e4SLinus Torvalds * the special cases of the former code. 551da177e4SLinus Torvalds * 561da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 571da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 581da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 591da177e4SLinus Torvalds * 601da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 611da177e4SLinus Torvalds * resolution to correspond with current state of the code. 621da177e4SLinus Torvalds * 631da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 641da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 651da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 661da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 671da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 681da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 691da177e4SLinus Torvalds */ 701da177e4SLinus Torvalds 711da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 721da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 731da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 741da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 751da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 761da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7725985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 781da177e4SLinus Torvalds * 791da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 801da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 811da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 821da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 831da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 841da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 851da177e4SLinus Torvalds * and in the old Linux semantics. 861da177e4SLinus Torvalds */ 871da177e4SLinus Torvalds 881da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 891da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 901da177e4SLinus Torvalds * 911da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 921da177e4SLinus Torvalds */ 931da177e4SLinus Torvalds 941da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 951da177e4SLinus Torvalds * inside the path - always follow. 961da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 971da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 981da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 991da177e4SLinus Torvalds * otherwise - don't follow. 1001da177e4SLinus Torvalds * (applied in that order). 1011da177e4SLinus Torvalds * 1021da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1031da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1041da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1051da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1061da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1071da177e4SLinus Torvalds */ 1081da177e4SLinus Torvalds /* 1091da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 110a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1111da177e4SLinus Torvalds * any extra contention... 1121da177e4SLinus Torvalds */ 1131da177e4SLinus Torvalds 1141da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1151da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1161da177e4SLinus Torvalds * kernel data space before using them.. 1171da177e4SLinus Torvalds * 1181da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1191da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1201da177e4SLinus Torvalds */ 1217950e385SJeff Layton 122fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12391a27b2aSJeff Layton 12451f39a1fSDavid Drysdale struct filename * 12591a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12691a27b2aSJeff Layton { 12794b5d262SAl Viro struct filename *result; 1287950e385SJeff Layton char *kname; 12994b5d262SAl Viro int len; 1301da177e4SLinus Torvalds 1317ac86265SJeff Layton result = audit_reusename(filename); 1327ac86265SJeff Layton if (result) 1337ac86265SJeff Layton return result; 1347ac86265SJeff Layton 1357950e385SJeff Layton result = __getname(); 1363f9f0aa6SLinus Torvalds if (unlikely(!result)) 1374043cde8SEric Paris return ERR_PTR(-ENOMEM); 1381da177e4SLinus Torvalds 1397950e385SJeff Layton /* 1407950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1417950e385SJeff Layton * allocation 1427950e385SJeff Layton */ 143fd2f7cb5SAl Viro kname = (char *)result->iname; 14491a27b2aSJeff Layton result->name = kname; 1457950e385SJeff Layton 14694b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 14791a27b2aSJeff Layton if (unlikely(len < 0)) { 14894b5d262SAl Viro __putname(result); 14994b5d262SAl Viro return ERR_PTR(len); 15091a27b2aSJeff Layton } 1513f9f0aa6SLinus Torvalds 1527950e385SJeff Layton /* 1537950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1547950e385SJeff Layton * separate struct filename so we can dedicate the entire 1557950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1567950e385SJeff Layton * userland. 1577950e385SJeff Layton */ 15894b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 159fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1607950e385SJeff Layton kname = (char *)result; 1617950e385SJeff Layton 162fd2f7cb5SAl Viro /* 163fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 164fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 165fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 166fd2f7cb5SAl Viro */ 167fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 16894b5d262SAl Viro if (unlikely(!result)) { 16994b5d262SAl Viro __putname(kname); 17094b5d262SAl Viro return ERR_PTR(-ENOMEM); 1717950e385SJeff Layton } 1727950e385SJeff Layton result->name = kname; 17394b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17494b5d262SAl Viro if (unlikely(len < 0)) { 17594b5d262SAl Viro __putname(kname); 17694b5d262SAl Viro kfree(result); 17794b5d262SAl Viro return ERR_PTR(len); 17894b5d262SAl Viro } 17994b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18094b5d262SAl Viro __putname(kname); 18194b5d262SAl Viro kfree(result); 18294b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18394b5d262SAl Viro } 1847950e385SJeff Layton } 1857950e385SJeff Layton 18694b5d262SAl Viro result->refcnt = 1; 1873f9f0aa6SLinus Torvalds /* The empty path is special. */ 1883f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1893f9f0aa6SLinus Torvalds if (empty) 1901fa1e7f6SAndy Whitcroft *empty = 1; 19194b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19294b5d262SAl Viro putname(result); 19394b5d262SAl Viro return ERR_PTR(-ENOENT); 1941da177e4SLinus Torvalds } 19594b5d262SAl Viro } 1967950e385SJeff Layton 1977950e385SJeff Layton result->uptr = filename; 198c4ad8f98SLinus Torvalds result->aname = NULL; 1991da177e4SLinus Torvalds audit_getname(result); 2001da177e4SLinus Torvalds return result; 2013f9f0aa6SLinus Torvalds } 2023f9f0aa6SLinus Torvalds 20391a27b2aSJeff Layton struct filename * 20491a27b2aSJeff Layton getname(const char __user * filename) 205f52e0c11SAl Viro { 206f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 207f52e0c11SAl Viro } 208f52e0c11SAl Viro 209c4ad8f98SLinus Torvalds struct filename * 210c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 211c4ad8f98SLinus Torvalds { 212c4ad8f98SLinus Torvalds struct filename *result; 21308518549SPaul Moore int len = strlen(filename) + 1; 214c4ad8f98SLinus Torvalds 215c4ad8f98SLinus Torvalds result = __getname(); 216c4ad8f98SLinus Torvalds if (unlikely(!result)) 217c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 218c4ad8f98SLinus Torvalds 21908518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 220fd2f7cb5SAl Viro result->name = (char *)result->iname; 22108518549SPaul Moore } else if (len <= PATH_MAX) { 22208518549SPaul Moore struct filename *tmp; 22308518549SPaul Moore 22408518549SPaul Moore tmp = kmalloc(sizeof(*tmp), GFP_KERNEL); 22508518549SPaul Moore if (unlikely(!tmp)) { 22608518549SPaul Moore __putname(result); 22708518549SPaul Moore return ERR_PTR(-ENOMEM); 22808518549SPaul Moore } 22908518549SPaul Moore tmp->name = (char *)result; 23008518549SPaul Moore result = tmp; 23108518549SPaul Moore } else { 23208518549SPaul Moore __putname(result); 23308518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23408518549SPaul Moore } 23508518549SPaul Moore memcpy((char *)result->name, filename, len); 236c4ad8f98SLinus Torvalds result->uptr = NULL; 237c4ad8f98SLinus Torvalds result->aname = NULL; 23855422d0bSPaul Moore result->refcnt = 1; 239fd3522fdSPaul Moore audit_getname(result); 240c4ad8f98SLinus Torvalds 241c4ad8f98SLinus Torvalds return result; 242c4ad8f98SLinus Torvalds } 243c4ad8f98SLinus Torvalds 24491a27b2aSJeff Layton void putname(struct filename *name) 2451da177e4SLinus Torvalds { 24655422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 24755422d0bSPaul Moore 24855422d0bSPaul Moore if (--name->refcnt > 0) 24955422d0bSPaul Moore return; 25055422d0bSPaul Moore 251fd2f7cb5SAl Viro if (name->name != name->iname) { 25255422d0bSPaul Moore __putname(name->name); 25355422d0bSPaul Moore kfree(name); 25455422d0bSPaul Moore } else 25555422d0bSPaul Moore __putname(name); 2561da177e4SLinus Torvalds } 2571da177e4SLinus Torvalds 258e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 259e77819e5SLinus Torvalds { 26084635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 261e77819e5SLinus Torvalds struct posix_acl *acl; 262e77819e5SLinus Torvalds 263e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2643567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2653567866bSAl Viro if (!acl) 266e77819e5SLinus Torvalds return -EAGAIN; 2673567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 2683567866bSAl Viro if (acl == ACL_NOT_CACHED) 269e77819e5SLinus Torvalds return -ECHILD; 270206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 271e77819e5SLinus Torvalds } 272e77819e5SLinus Torvalds 2732982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2744e34e719SChristoph Hellwig if (IS_ERR(acl)) 2754e34e719SChristoph Hellwig return PTR_ERR(acl); 276e77819e5SLinus Torvalds if (acl) { 277e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 278e77819e5SLinus Torvalds posix_acl_release(acl); 279e77819e5SLinus Torvalds return error; 280e77819e5SLinus Torvalds } 28184635d68SLinus Torvalds #endif 282e77819e5SLinus Torvalds 283e77819e5SLinus Torvalds return -EAGAIN; 284e77819e5SLinus Torvalds } 285e77819e5SLinus Torvalds 2865909ccaaSLinus Torvalds /* 287948409c7SAndreas Gruenbacher * This does the basic permission checking 2885909ccaaSLinus Torvalds */ 2897e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2905909ccaaSLinus Torvalds { 29126cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2925909ccaaSLinus Torvalds 2938e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2945909ccaaSLinus Torvalds mode >>= 6; 2955909ccaaSLinus Torvalds else { 296e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2977e40145eSAl Viro int error = check_acl(inode, mask); 2985909ccaaSLinus Torvalds if (error != -EAGAIN) 2995909ccaaSLinus Torvalds return error; 3005909ccaaSLinus Torvalds } 3015909ccaaSLinus Torvalds 3025909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3035909ccaaSLinus Torvalds mode >>= 3; 3045909ccaaSLinus Torvalds } 3055909ccaaSLinus Torvalds 3065909ccaaSLinus Torvalds /* 3075909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3085909ccaaSLinus Torvalds */ 3099c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3105909ccaaSLinus Torvalds return 0; 3115909ccaaSLinus Torvalds return -EACCES; 3125909ccaaSLinus Torvalds } 3131da177e4SLinus Torvalds 3141da177e4SLinus Torvalds /** 3151da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3161da177e4SLinus Torvalds * @inode: inode to check access rights for 3178fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3181da177e4SLinus Torvalds * 3191da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3201da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3211da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 322b74c79e9SNick Piggin * are used for other things. 323b74c79e9SNick Piggin * 324b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 325b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 326b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3271da177e4SLinus Torvalds */ 3282830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3291da177e4SLinus Torvalds { 3305909ccaaSLinus Torvalds int ret; 3311da177e4SLinus Torvalds 3321da177e4SLinus Torvalds /* 333948409c7SAndreas Gruenbacher * Do the basic permission checks. 3341da177e4SLinus Torvalds */ 3357e40145eSAl Viro ret = acl_permission_check(inode, mask); 3365909ccaaSLinus Torvalds if (ret != -EACCES) 3375909ccaaSLinus Torvalds return ret; 3381da177e4SLinus Torvalds 339d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 340d594e7ecSAl Viro /* DACs are overridable for directories */ 34123adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 342d594e7ecSAl Viro return 0; 343d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34423adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34523adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 346d594e7ecSAl Viro return 0; 347d594e7ecSAl Viro return -EACCES; 348d594e7ecSAl Viro } 3491da177e4SLinus Torvalds /* 3501da177e4SLinus Torvalds * Read/write DACs are always overridable. 351d594e7ecSAl Viro * Executable DACs are overridable when there is 352d594e7ecSAl Viro * at least one exec bit set. 3531da177e4SLinus Torvalds */ 354d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 35523adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3561da177e4SLinus Torvalds return 0; 3571da177e4SLinus Torvalds 3581da177e4SLinus Torvalds /* 3591da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3601da177e4SLinus Torvalds */ 3617ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 362d594e7ecSAl Viro if (mask == MAY_READ) 36323adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3641da177e4SLinus Torvalds return 0; 3651da177e4SLinus Torvalds 3661da177e4SLinus Torvalds return -EACCES; 3671da177e4SLinus Torvalds } 3684d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3691da177e4SLinus Torvalds 3703ddcd056SLinus Torvalds /* 3713ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3723ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3733ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3743ddcd056SLinus Torvalds * permission function, use the fast case". 3753ddcd056SLinus Torvalds */ 3763ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3773ddcd056SLinus Torvalds { 3783ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3793ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3803ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3813ddcd056SLinus Torvalds 3823ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3833ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3843ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3853ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3863ddcd056SLinus Torvalds } 3873ddcd056SLinus Torvalds return generic_permission(inode, mask); 3883ddcd056SLinus Torvalds } 3893ddcd056SLinus Torvalds 390cb23beb5SChristoph Hellwig /** 3910bdaea90SDavid Howells * __inode_permission - Check for access rights to a given inode 3920bdaea90SDavid Howells * @inode: Inode to check permission on 3930bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 394cb23beb5SChristoph Hellwig * 3950bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. 396948409c7SAndreas Gruenbacher * 397948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 3980bdaea90SDavid Howells * 3990bdaea90SDavid Howells * This does not check for a read-only file system. You probably want 4000bdaea90SDavid Howells * inode_permission(). 401cb23beb5SChristoph Hellwig */ 4020bdaea90SDavid Howells int __inode_permission(struct inode *inode, int mask) 4031da177e4SLinus Torvalds { 404e6305c43SAl Viro int retval; 4051da177e4SLinus Torvalds 4063ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 4071da177e4SLinus Torvalds /* 4081da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 4091da177e4SLinus Torvalds */ 4101da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 4111da177e4SLinus Torvalds return -EACCES; 4121da177e4SLinus Torvalds } 4131da177e4SLinus Torvalds 4143ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 4151da177e4SLinus Torvalds if (retval) 4161da177e4SLinus Torvalds return retval; 4171da177e4SLinus Torvalds 41808ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 41908ce5f16SSerge E. Hallyn if (retval) 42008ce5f16SSerge E. Hallyn return retval; 42108ce5f16SSerge E. Hallyn 422d09ca739SEric Paris return security_inode_permission(inode, mask); 4231da177e4SLinus Torvalds } 424bd5d0856SMiklos Szeredi EXPORT_SYMBOL(__inode_permission); 4251da177e4SLinus Torvalds 426f4d6ff89SAl Viro /** 4270bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 4280bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 42955852635SRandy Dunlap * @inode: Inode to check permission on 4300bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4310bdaea90SDavid Howells * 4320bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4330bdaea90SDavid Howells */ 4340bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4350bdaea90SDavid Howells { 4360bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4370bdaea90SDavid Howells umode_t mode = inode->i_mode; 4380bdaea90SDavid Howells 4390bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 4400bdaea90SDavid Howells if ((sb->s_flags & MS_RDONLY) && 4410bdaea90SDavid Howells (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4420bdaea90SDavid Howells return -EROFS; 4430bdaea90SDavid Howells } 4440bdaea90SDavid Howells return 0; 4450bdaea90SDavid Howells } 4460bdaea90SDavid Howells 4470bdaea90SDavid Howells /** 4480bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4490bdaea90SDavid Howells * @inode: Inode to check permission on 4500bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4510bdaea90SDavid Howells * 4520bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4530bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4540bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4550bdaea90SDavid Howells * 4560bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4570bdaea90SDavid Howells */ 4580bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4590bdaea90SDavid Howells { 4600bdaea90SDavid Howells int retval; 4610bdaea90SDavid Howells 4620bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4630bdaea90SDavid Howells if (retval) 4640bdaea90SDavid Howells return retval; 4650bdaea90SDavid Howells return __inode_permission(inode, mask); 4660bdaea90SDavid Howells } 4674d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4680bdaea90SDavid Howells 4690bdaea90SDavid Howells /** 4705dd784d0SJan Blunck * path_get - get a reference to a path 4715dd784d0SJan Blunck * @path: path to get the reference to 4725dd784d0SJan Blunck * 4735dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4745dd784d0SJan Blunck */ 475dcf787f3SAl Viro void path_get(const struct path *path) 4765dd784d0SJan Blunck { 4775dd784d0SJan Blunck mntget(path->mnt); 4785dd784d0SJan Blunck dget(path->dentry); 4795dd784d0SJan Blunck } 4805dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4815dd784d0SJan Blunck 4825dd784d0SJan Blunck /** 4831d957f9bSJan Blunck * path_put - put a reference to a path 4841d957f9bSJan Blunck * @path: path to put the reference to 4851d957f9bSJan Blunck * 4861d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4871d957f9bSJan Blunck */ 488dcf787f3SAl Viro void path_put(const struct path *path) 4891da177e4SLinus Torvalds { 4901d957f9bSJan Blunck dput(path->dentry); 4911d957f9bSJan Blunck mntput(path->mnt); 4921da177e4SLinus Torvalds } 4931d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4941da177e4SLinus Torvalds 495894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 4961f55a6ecSAl Viro struct nameidata { 4971f55a6ecSAl Viro struct path path; 4981f55a6ecSAl Viro struct qstr last; 4991f55a6ecSAl Viro struct path root; 5001f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 5011f55a6ecSAl Viro unsigned int flags; 5021f55a6ecSAl Viro unsigned seq, m_seq; 5031f55a6ecSAl Viro int last_type; 5041f55a6ecSAl Viro unsigned depth; 505756daf26SNeilBrown int total_link_count; 5065e53084dSAl Viro struct file *base; 507697fc6caSAl Viro struct saved { 508697fc6caSAl Viro struct path link; 509697fc6caSAl Viro void *cookie; 510697fc6caSAl Viro const char *name; 511894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5121f55a6ecSAl Viro }; 5131f55a6ecSAl Viro 514756daf26SNeilBrown static struct nameidata *set_nameidata(struct nameidata *p) 515894bc8c4SAl Viro { 516756daf26SNeilBrown struct nameidata *old = current->nameidata; 517756daf26SNeilBrown p->stack = p->internal; 518756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 519756daf26SNeilBrown current->nameidata = p; 520756daf26SNeilBrown return old; 521894bc8c4SAl Viro } 522894bc8c4SAl Viro 523756daf26SNeilBrown static void restore_nameidata(struct nameidata *old) 524894bc8c4SAl Viro { 525756daf26SNeilBrown struct nameidata *now = current->nameidata; 526756daf26SNeilBrown 527756daf26SNeilBrown current->nameidata = old; 528756daf26SNeilBrown if (old) 529756daf26SNeilBrown old->total_link_count = now->total_link_count; 530756daf26SNeilBrown if (now->stack != now->internal) { 531756daf26SNeilBrown kfree(now->stack); 532756daf26SNeilBrown now->stack = now->internal; 533894bc8c4SAl Viro } 534894bc8c4SAl Viro } 535894bc8c4SAl Viro 536894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 537894bc8c4SAl Viro { 538e269f2a7SAl Viro struct saved *p = kmalloc(MAXSYMLINKS * sizeof(struct saved), 539894bc8c4SAl Viro GFP_KERNEL); 540894bc8c4SAl Viro if (unlikely(!p)) 541894bc8c4SAl Viro return -ENOMEM; 542894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 543894bc8c4SAl Viro nd->stack = p; 544894bc8c4SAl Viro return 0; 545894bc8c4SAl Viro } 546894bc8c4SAl Viro 547894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 548894bc8c4SAl Viro { 549da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 550894bc8c4SAl Viro return 0; 551894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 552894bc8c4SAl Viro return 0; 553894bc8c4SAl Viro return __nd_alloc_stack(nd); 554894bc8c4SAl Viro } 555894bc8c4SAl Viro 55619660af7SAl Viro /* 55731e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 55819660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 55919660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 56019660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 56119660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 56219660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 56319660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 56419660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 56531e6b01fSNick Piggin */ 56631e6b01fSNick Piggin 567e8bb73dfSAl Viro static void terminate_walk(struct nameidata *nd); 568e8bb73dfSAl Viro 56931e6b01fSNick Piggin /** 57019660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 57119660af7SAl Viro * @nd: nameidata pathwalk data 57219660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 57339191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 57431e6b01fSNick Piggin * 57519660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 57619660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 57719660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 57831e6b01fSNick Piggin */ 57919660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 58031e6b01fSNick Piggin { 58131e6b01fSNick Piggin struct fs_struct *fs = current->fs; 58231e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 58331e6b01fSNick Piggin 58431e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 585e5c832d5SLinus Torvalds 586e5c832d5SLinus Torvalds /* 58748a066e7SAl Viro * After legitimizing the bastards, terminate_walk() 58848a066e7SAl Viro * will do the right thing for non-RCU mode, and all our 58948a066e7SAl Viro * subsequent exit cases should rcu_read_unlock() 59048a066e7SAl Viro * before returning. Do vfsmount first; if dentry 59148a066e7SAl Viro * can't be legitimized, just set nd->path.dentry to NULL 59248a066e7SAl Viro * and rely on dput(NULL) being a no-op. 593e5c832d5SLinus Torvalds */ 59448a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) 595e5c832d5SLinus Torvalds return -ECHILD; 596e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 59715570086SLinus Torvalds 59848a066e7SAl Viro if (!lockref_get_not_dead(&parent->d_lockref)) { 59948a066e7SAl Viro nd->path.dentry = NULL; 600d870b4a1SAl Viro goto out; 60148a066e7SAl Viro } 60248a066e7SAl Viro 60315570086SLinus Torvalds /* 60415570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 60515570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 60615570086SLinus Torvalds * 60715570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 60815570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 60915570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 61015570086SLinus Torvalds * since we checked the sequence number of the parent after we got 61115570086SLinus Torvalds * the child sequence number. So we know the parent must still 61215570086SLinus Torvalds * be valid if the child sequence number is still valid. 61315570086SLinus Torvalds */ 61419660af7SAl Viro if (!dentry) { 615e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 616e5c832d5SLinus Torvalds goto out; 61719660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 61819660af7SAl Viro } else { 619e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 620e5c832d5SLinus Torvalds goto out; 621e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) 622e5c832d5SLinus Torvalds goto drop_dentry; 62319660af7SAl Viro } 624e5c832d5SLinus Torvalds 625e5c832d5SLinus Torvalds /* 626e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 627e5c832d5SLinus Torvalds * still valid and get it if required. 628e5c832d5SLinus Torvalds */ 629e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 630e5c832d5SLinus Torvalds spin_lock(&fs->lock); 631e5c832d5SLinus Torvalds if (nd->root.mnt != fs->root.mnt || nd->root.dentry != fs->root.dentry) 632e5c832d5SLinus Torvalds goto unlock_and_drop_dentry; 63331e6b01fSNick Piggin path_get(&nd->root); 63431e6b01fSNick Piggin spin_unlock(&fs->lock); 63531e6b01fSNick Piggin } 63631e6b01fSNick Piggin 6378b61e74fSAl Viro rcu_read_unlock(); 63831e6b01fSNick Piggin return 0; 63919660af7SAl Viro 640e5c832d5SLinus Torvalds unlock_and_drop_dentry: 64131e6b01fSNick Piggin spin_unlock(&fs->lock); 642e5c832d5SLinus Torvalds drop_dentry: 6438b61e74fSAl Viro rcu_read_unlock(); 644e5c832d5SLinus Torvalds dput(dentry); 645d0d27277SLinus Torvalds goto drop_root_mnt; 646e5c832d5SLinus Torvalds out: 6478b61e74fSAl Viro rcu_read_unlock(); 648d0d27277SLinus Torvalds drop_root_mnt: 649d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 650d0d27277SLinus Torvalds nd->root.mnt = NULL; 65131e6b01fSNick Piggin return -ECHILD; 65231e6b01fSNick Piggin } 65331e6b01fSNick Piggin 6544ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 65534286d66SNick Piggin { 6564ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 65734286d66SNick Piggin } 65834286d66SNick Piggin 6599f1fafeeSAl Viro /** 6609f1fafeeSAl Viro * complete_walk - successful completion of path walk 6619f1fafeeSAl Viro * @nd: pointer nameidata 66239159de2SJeff Layton * 6639f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 6649f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 6659f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 6669f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 6679f1fafeeSAl Viro * need to drop nd->path. 66839159de2SJeff Layton */ 6699f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 67039159de2SJeff Layton { 67116c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 67239159de2SJeff Layton int status; 67339159de2SJeff Layton 6749f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 6759f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6769f1fafeeSAl Viro nd->root.mnt = NULL; 677e8bb73dfSAl Viro if (unlikely(unlazy_walk(nd, NULL))) { 678e8bb73dfSAl Viro terminate_walk(nd); 67948a066e7SAl Viro return -ECHILD; 68048a066e7SAl Viro } 6819f1fafeeSAl Viro } 6829f1fafeeSAl Viro 68316c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 68439159de2SJeff Layton return 0; 68539159de2SJeff Layton 686ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 68716c2cd71SAl Viro return 0; 68816c2cd71SAl Viro 689ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 69039159de2SJeff Layton if (status > 0) 69139159de2SJeff Layton return 0; 69239159de2SJeff Layton 69316c2cd71SAl Viro if (!status) 69439159de2SJeff Layton status = -ESTALE; 69516c2cd71SAl Viro 696e8bb73dfSAl Viro terminate_walk(nd); 69739159de2SJeff Layton return status; 69839159de2SJeff Layton } 69939159de2SJeff Layton 7002a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 7012a737871SAl Viro { 702f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 7032a737871SAl Viro } 7042a737871SAl Viro 7057bd88377SAl Viro static __always_inline unsigned set_root_rcu(struct nameidata *nd) 70631e6b01fSNick Piggin { 70731e6b01fSNick Piggin struct fs_struct *fs = current->fs; 7087bd88377SAl Viro unsigned seq, res; 709c28cc364SNick Piggin 710c28cc364SNick Piggin do { 711c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 71231e6b01fSNick Piggin nd->root = fs->root; 7137bd88377SAl Viro res = __read_seqcount_begin(&nd->root.dentry->d_seq); 714c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 7157bd88377SAl Viro return res; 71631e6b01fSNick Piggin } 71731e6b01fSNick Piggin 7181d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 719051d3812SIan Kent { 720051d3812SIan Kent dput(path->dentry); 7214ac91378SJan Blunck if (path->mnt != nd->path.mnt) 722051d3812SIan Kent mntput(path->mnt); 723051d3812SIan Kent } 724051d3812SIan Kent 7257b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 7267b9337aaSNick Piggin struct nameidata *nd) 727051d3812SIan Kent { 72831e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 7294ac91378SJan Blunck dput(nd->path.dentry); 73031e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 7314ac91378SJan Blunck mntput(nd->path.mnt); 7329a229683SHuang Shijie } 73331e6b01fSNick Piggin nd->path.mnt = path->mnt; 7344ac91378SJan Blunck nd->path.dentry = path->dentry; 735051d3812SIan Kent } 736051d3812SIan Kent 737b5fb63c1SChristoph Hellwig /* 738b5fb63c1SChristoph Hellwig * Helper to directly jump to a known parsed path from ->follow_link, 739b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 740b5fb63c1SChristoph Hellwig */ 7416e77137bSAl Viro void nd_jump_link(struct path *path) 742b5fb63c1SChristoph Hellwig { 7436e77137bSAl Viro struct nameidata *nd = current->nameidata; 744b5fb63c1SChristoph Hellwig path_put(&nd->path); 745b5fb63c1SChristoph Hellwig 746b5fb63c1SChristoph Hellwig nd->path = *path; 747b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 748b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 749b5fb63c1SChristoph Hellwig } 750b5fb63c1SChristoph Hellwig 751b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 752574197e0SAl Viro { 75321c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 754b9ff4429SAl Viro struct inode *inode = last->link.dentry->d_inode; 755b9ff4429SAl Viro if (last->cookie && inode->i_op->put_link) 756b9ff4429SAl Viro inode->i_op->put_link(last->link.dentry, last->cookie); 757b9ff4429SAl Viro path_put(&last->link); 758574197e0SAl Viro } 759574197e0SAl Viro 760561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 761561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 762800179c9SKees Cook 763800179c9SKees Cook /** 764800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 76555852635SRandy Dunlap * @nd: nameidata pathwalk data 766800179c9SKees Cook * 767800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 768800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 769800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 770800179c9SKees Cook * processes from failing races against path names that may change out 771800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 772800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 773800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 774800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 775800179c9SKees Cook * 776800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 777800179c9SKees Cook */ 778fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 779800179c9SKees Cook { 780800179c9SKees Cook const struct inode *inode; 781800179c9SKees Cook const struct inode *parent; 782800179c9SKees Cook 783800179c9SKees Cook if (!sysctl_protected_symlinks) 784800179c9SKees Cook return 0; 785800179c9SKees Cook 786800179c9SKees Cook /* Allowed if owner and follower match. */ 7871cf2665bSAl Viro inode = nd->stack[0].link.dentry->d_inode; 78881abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 789800179c9SKees Cook return 0; 790800179c9SKees Cook 791800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 792800179c9SKees Cook parent = nd->path.dentry->d_inode; 793800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 794800179c9SKees Cook return 0; 795800179c9SKees Cook 796800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 79781abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 798800179c9SKees Cook return 0; 799800179c9SKees Cook 8001cf2665bSAl Viro audit_log_link_denied("follow_link", &nd->stack[0].link); 801800179c9SKees Cook return -EACCES; 802800179c9SKees Cook } 803800179c9SKees Cook 804800179c9SKees Cook /** 805800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 806800179c9SKees Cook * @inode: the source inode to hardlink from 807800179c9SKees Cook * 808800179c9SKees Cook * Return false if at least one of the following conditions: 809800179c9SKees Cook * - inode is not a regular file 810800179c9SKees Cook * - inode is setuid 811800179c9SKees Cook * - inode is setgid and group-exec 812800179c9SKees Cook * - access failure for read and write 813800179c9SKees Cook * 814800179c9SKees Cook * Otherwise returns true. 815800179c9SKees Cook */ 816800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 817800179c9SKees Cook { 818800179c9SKees Cook umode_t mode = inode->i_mode; 819800179c9SKees Cook 820800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 821800179c9SKees Cook if (!S_ISREG(mode)) 822800179c9SKees Cook return false; 823800179c9SKees Cook 824800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 825800179c9SKees Cook if (mode & S_ISUID) 826800179c9SKees Cook return false; 827800179c9SKees Cook 828800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 829800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 830800179c9SKees Cook return false; 831800179c9SKees Cook 832800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 833800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 834800179c9SKees Cook return false; 835800179c9SKees Cook 836800179c9SKees Cook return true; 837800179c9SKees Cook } 838800179c9SKees Cook 839800179c9SKees Cook /** 840800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 841800179c9SKees Cook * @link: the source to hardlink from 842800179c9SKees Cook * 843800179c9SKees Cook * Block hardlink when all of: 844800179c9SKees Cook * - sysctl_protected_hardlinks enabled 845800179c9SKees Cook * - fsuid does not match inode 846800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 847800179c9SKees Cook * - not CAP_FOWNER 848800179c9SKees Cook * 849800179c9SKees Cook * Returns 0 if successful, -ve on error. 850800179c9SKees Cook */ 851800179c9SKees Cook static int may_linkat(struct path *link) 852800179c9SKees Cook { 853800179c9SKees Cook const struct cred *cred; 854800179c9SKees Cook struct inode *inode; 855800179c9SKees Cook 856800179c9SKees Cook if (!sysctl_protected_hardlinks) 857800179c9SKees Cook return 0; 858800179c9SKees Cook 859800179c9SKees Cook cred = current_cred(); 860800179c9SKees Cook inode = link->dentry->d_inode; 861800179c9SKees Cook 862800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 863800179c9SKees Cook * otherwise, it must be a safe source. 864800179c9SKees Cook */ 86581abe27bSEric W. Biederman if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || 866800179c9SKees Cook capable(CAP_FOWNER)) 867800179c9SKees Cook return 0; 868800179c9SKees Cook 869a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 870800179c9SKees Cook return -EPERM; 871800179c9SKees Cook } 872800179c9SKees Cook 8733b2e7f75SAl Viro static __always_inline 8743b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 8751da177e4SLinus Torvalds { 876ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 8771cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 8780a959df5SAl Viro struct inode *inode = dentry->d_inode; 8796d7b5aaeSAl Viro int error; 8800a959df5SAl Viro const char *res; 8811da177e4SLinus Torvalds 882844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 883844a3917SAl Viro 884574197e0SAl Viro cond_resched(); 885574197e0SAl Viro 8863b2e7f75SAl Viro touch_atime(&last->link); 887cd4e91d3SAl Viro 88837882db0SNeilBrown error = security_inode_follow_link(dentry); 8896d7b5aaeSAl Viro if (error) 8906920a440SAl Viro return ERR_PTR(error); 89136f3b4f6SAl Viro 89286acdca1SAl Viro nd->last_type = LAST_BIND; 893d4dee48bSAl Viro res = inode->i_link; 894d4dee48bSAl Viro if (!res) { 8956e77137bSAl Viro res = inode->i_op->follow_link(dentry, &last->cookie); 896fab51e8aSAl Viro if (IS_ERR_OR_NULL(res)) { 8976920a440SAl Viro last->cookie = NULL; 898fab51e8aSAl Viro return res; 8990a959df5SAl Viro } 900fab51e8aSAl Viro } 901fab51e8aSAl Viro if (*res == '/') { 902fab51e8aSAl Viro if (!nd->root.mnt) 903fab51e8aSAl Viro set_root(nd); 904fab51e8aSAl Viro path_put(&nd->path); 905fab51e8aSAl Viro nd->path = nd->root; 906fab51e8aSAl Viro path_get(&nd->root); 907fab51e8aSAl Viro nd->inode = nd->path.dentry->d_inode; 908fab51e8aSAl Viro nd->flags |= LOOKUP_JUMPED; 909fab51e8aSAl Viro while (unlikely(*++res == '/')) 910fab51e8aSAl Viro ; 911fab51e8aSAl Viro } 912fab51e8aSAl Viro if (!*res) 913fab51e8aSAl Viro res = NULL; 9140a959df5SAl Viro return res; 9150a959df5SAl Viro } 9166d7b5aaeSAl Viro 91731e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 91831e6b01fSNick Piggin { 9190714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9200714a533SAl Viro struct mount *parent; 92131e6b01fSNick Piggin struct dentry *mountpoint; 92231e6b01fSNick Piggin 9230714a533SAl Viro parent = mnt->mnt_parent; 9240714a533SAl Viro if (&parent->mnt == path->mnt) 92531e6b01fSNick Piggin return 0; 926a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 92731e6b01fSNick Piggin path->dentry = mountpoint; 9280714a533SAl Viro path->mnt = &parent->mnt; 92931e6b01fSNick Piggin return 1; 93031e6b01fSNick Piggin } 93131e6b01fSNick Piggin 932f015f126SDavid Howells /* 933f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 934f015f126SDavid Howells * 935f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 936f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 937f015f126SDavid Howells * Up is towards /. 938f015f126SDavid Howells * 939f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 940f015f126SDavid Howells * root. 941f015f126SDavid Howells */ 942bab77ebfSAl Viro int follow_up(struct path *path) 9431da177e4SLinus Torvalds { 9440714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9450714a533SAl Viro struct mount *parent; 9461da177e4SLinus Torvalds struct dentry *mountpoint; 94799b7db7bSNick Piggin 94848a066e7SAl Viro read_seqlock_excl(&mount_lock); 9490714a533SAl Viro parent = mnt->mnt_parent; 9503c0a6163SAl Viro if (parent == mnt) { 95148a066e7SAl Viro read_sequnlock_excl(&mount_lock); 9521da177e4SLinus Torvalds return 0; 9531da177e4SLinus Torvalds } 9540714a533SAl Viro mntget(&parent->mnt); 955a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 95648a066e7SAl Viro read_sequnlock_excl(&mount_lock); 957bab77ebfSAl Viro dput(path->dentry); 958bab77ebfSAl Viro path->dentry = mountpoint; 959bab77ebfSAl Viro mntput(path->mnt); 9600714a533SAl Viro path->mnt = &parent->mnt; 9611da177e4SLinus Torvalds return 1; 9621da177e4SLinus Torvalds } 9634d359507SAl Viro EXPORT_SYMBOL(follow_up); 9641da177e4SLinus Torvalds 965b5c84bf6SNick Piggin /* 9669875cf80SDavid Howells * Perform an automount 9679875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 9689875cf80SDavid Howells * were called with. 9691da177e4SLinus Torvalds */ 970756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 9719875cf80SDavid Howells bool *need_mntput) 97231e6b01fSNick Piggin { 9739875cf80SDavid Howells struct vfsmount *mnt; 974ea5b778aSDavid Howells int err; 9759875cf80SDavid Howells 9769875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 9779875cf80SDavid Howells return -EREMOTE; 9789875cf80SDavid Howells 9790ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 9800ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 9810ec26fd0SMiklos Szeredi * the name. 9820ec26fd0SMiklos Szeredi * 9830ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 9845a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 9850ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 9860ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 9870ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 9880ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 9895a30d8a2SDavid Howells */ 990756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 991d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 9925a30d8a2SDavid Howells path->dentry->d_inode) 9939875cf80SDavid Howells return -EISDIR; 9940ec26fd0SMiklos Szeredi 995756daf26SNeilBrown nd->total_link_count++; 996756daf26SNeilBrown if (nd->total_link_count >= 40) 9979875cf80SDavid Howells return -ELOOP; 9989875cf80SDavid Howells 9999875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 10009875cf80SDavid Howells if (IS_ERR(mnt)) { 10019875cf80SDavid Howells /* 10029875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 10039875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 10049875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 10059875cf80SDavid Howells * 10069875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 10079875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 10089875cf80SDavid Howells * the path is inaccessible and we should say so. 10099875cf80SDavid Howells */ 1010756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 10119875cf80SDavid Howells return -EREMOTE; 10129875cf80SDavid Howells return PTR_ERR(mnt); 101331e6b01fSNick Piggin } 1014ea5b778aSDavid Howells 10159875cf80SDavid Howells if (!mnt) /* mount collision */ 10169875cf80SDavid Howells return 0; 10179875cf80SDavid Howells 10188aef1884SAl Viro if (!*need_mntput) { 10198aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 10208aef1884SAl Viro mntget(path->mnt); 10218aef1884SAl Viro *need_mntput = true; 10228aef1884SAl Viro } 102319a167afSAl Viro err = finish_automount(mnt, path); 1024ea5b778aSDavid Howells 1025ea5b778aSDavid Howells switch (err) { 1026ea5b778aSDavid Howells case -EBUSY: 1027ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 102819a167afSAl Viro return 0; 1029ea5b778aSDavid Howells case 0: 10308aef1884SAl Viro path_put(path); 10319875cf80SDavid Howells path->mnt = mnt; 10329875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 10339875cf80SDavid Howells return 0; 103419a167afSAl Viro default: 103519a167afSAl Viro return err; 10369875cf80SDavid Howells } 103719a167afSAl Viro 1038ea5b778aSDavid Howells } 10399875cf80SDavid Howells 10409875cf80SDavid Howells /* 10419875cf80SDavid Howells * Handle a dentry that is managed in some way. 1042cc53ce53SDavid Howells * - Flagged for transit management (autofs) 10439875cf80SDavid Howells * - Flagged as mountpoint 10449875cf80SDavid Howells * - Flagged as automount point 10459875cf80SDavid Howells * 10469875cf80SDavid Howells * This may only be called in refwalk mode. 10479875cf80SDavid Howells * 10489875cf80SDavid Howells * Serialization is taken care of in namespace.c 10499875cf80SDavid Howells */ 1050756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 10519875cf80SDavid Howells { 10528aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 10539875cf80SDavid Howells unsigned managed; 10549875cf80SDavid Howells bool need_mntput = false; 10558aef1884SAl Viro int ret = 0; 10569875cf80SDavid Howells 10579875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 10589875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 10599875cf80SDavid Howells * the components of that value change under us */ 10609875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 10619875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 10629875cf80SDavid Howells unlikely(managed != 0)) { 1063cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1064cc53ce53SDavid Howells * being held. */ 1065cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1066cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1067cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 10681aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1069cc53ce53SDavid Howells if (ret < 0) 10708aef1884SAl Viro break; 1071cc53ce53SDavid Howells } 1072cc53ce53SDavid Howells 10739875cf80SDavid Howells /* Transit to a mounted filesystem. */ 10749875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 10759875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10769875cf80SDavid Howells if (mounted) { 10779875cf80SDavid Howells dput(path->dentry); 10789875cf80SDavid Howells if (need_mntput) 1079463ffb2eSAl Viro mntput(path->mnt); 1080463ffb2eSAl Viro path->mnt = mounted; 1081463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 10829875cf80SDavid Howells need_mntput = true; 10839875cf80SDavid Howells continue; 1084463ffb2eSAl Viro } 1085463ffb2eSAl Viro 10869875cf80SDavid Howells /* Something is mounted on this dentry in another 10879875cf80SDavid Howells * namespace and/or whatever was mounted there in this 108848a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 108948a066e7SAl Viro * get it */ 10901da177e4SLinus Torvalds } 10919875cf80SDavid Howells 10929875cf80SDavid Howells /* Handle an automount point */ 10939875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1094756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 10959875cf80SDavid Howells if (ret < 0) 10968aef1884SAl Viro break; 10979875cf80SDavid Howells continue; 10989875cf80SDavid Howells } 10999875cf80SDavid Howells 11009875cf80SDavid Howells /* We didn't change the current path point */ 11019875cf80SDavid Howells break; 11029875cf80SDavid Howells } 11038aef1884SAl Viro 11048aef1884SAl Viro if (need_mntput && path->mnt == mnt) 11058aef1884SAl Viro mntput(path->mnt); 11068aef1884SAl Viro if (ret == -EISDIR) 11078aef1884SAl Viro ret = 0; 11088402752eSAl Viro if (need_mntput) 11098402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 11108402752eSAl Viro if (unlikely(ret < 0)) 11118402752eSAl Viro path_put_conditional(path, nd); 11128402752eSAl Viro return ret; 11131da177e4SLinus Torvalds } 11141da177e4SLinus Torvalds 1115cc53ce53SDavid Howells int follow_down_one(struct path *path) 11161da177e4SLinus Torvalds { 11171da177e4SLinus Torvalds struct vfsmount *mounted; 11181da177e4SLinus Torvalds 11191c755af4SAl Viro mounted = lookup_mnt(path); 11201da177e4SLinus Torvalds if (mounted) { 11219393bd07SAl Viro dput(path->dentry); 11229393bd07SAl Viro mntput(path->mnt); 11239393bd07SAl Viro path->mnt = mounted; 11249393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 11251da177e4SLinus Torvalds return 1; 11261da177e4SLinus Torvalds } 11271da177e4SLinus Torvalds return 0; 11281da177e4SLinus Torvalds } 11294d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 11301da177e4SLinus Torvalds 1131b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 113262a7375eSIan Kent { 1133b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1134b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 113562a7375eSIan Kent } 113662a7375eSIan Kent 11379875cf80SDavid Howells /* 1138287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1139287548e4SAl Viro * we meet a managed dentry that would need blocking. 11409875cf80SDavid Howells */ 11419875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1142287548e4SAl Viro struct inode **inode) 11439875cf80SDavid Howells { 114462a7375eSIan Kent for (;;) { 1145c7105365SAl Viro struct mount *mounted; 114662a7375eSIan Kent /* 114762a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 114862a7375eSIan Kent * that wants to block transit. 114962a7375eSIan Kent */ 1150b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1151b8faf035SNeilBrown case -ECHILD: 1152b8faf035SNeilBrown default: 1153ab90911fSDavid Howells return false; 1154b8faf035SNeilBrown case -EISDIR: 1155b8faf035SNeilBrown return true; 1156b8faf035SNeilBrown case 0: 1157b8faf035SNeilBrown break; 1158b8faf035SNeilBrown } 115962a7375eSIan Kent 116062a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1161b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 116262a7375eSIan Kent 1163474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 11649875cf80SDavid Howells if (!mounted) 11659875cf80SDavid Howells break; 1166c7105365SAl Viro path->mnt = &mounted->mnt; 1167c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1168a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 11699875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 117059430262SLinus Torvalds /* 117159430262SLinus Torvalds * Update the inode too. We don't need to re-check the 117259430262SLinus Torvalds * dentry sequence number here after this d_inode read, 117359430262SLinus Torvalds * because a mount-point is always pinned. 117459430262SLinus Torvalds */ 117559430262SLinus Torvalds *inode = path->dentry->d_inode; 11769875cf80SDavid Howells } 1177f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1178b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1179287548e4SAl Viro } 1180287548e4SAl Viro 118131e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 118231e6b01fSNick Piggin { 11834023bfc9SAl Viro struct inode *inode = nd->inode; 11847bd88377SAl Viro if (!nd->root.mnt) 118531e6b01fSNick Piggin set_root_rcu(nd); 118631e6b01fSNick Piggin 118731e6b01fSNick Piggin while (1) { 118831e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 118931e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 119031e6b01fSNick Piggin break; 119131e6b01fSNick Piggin } 119231e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 119331e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 119431e6b01fSNick Piggin struct dentry *parent = old->d_parent; 119531e6b01fSNick Piggin unsigned seq; 119631e6b01fSNick Piggin 11974023bfc9SAl Viro inode = parent->d_inode; 119831e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 119931e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1200ef7562d5SAl Viro goto failed; 120131e6b01fSNick Piggin nd->path.dentry = parent; 120231e6b01fSNick Piggin nd->seq = seq; 120331e6b01fSNick Piggin break; 120431e6b01fSNick Piggin } 120531e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 120631e6b01fSNick Piggin break; 12074023bfc9SAl Viro inode = nd->path.dentry->d_inode; 120831e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 120931e6b01fSNick Piggin } 1210b37199e6SAl Viro while (d_mountpoint(nd->path.dentry)) { 1211b37199e6SAl Viro struct mount *mounted; 1212b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1213b37199e6SAl Viro if (!mounted) 1214b37199e6SAl Viro break; 1215b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1216b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 12174023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1218b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1219f5be3e29SAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1220b37199e6SAl Viro goto failed; 1221b37199e6SAl Viro } 12224023bfc9SAl Viro nd->inode = inode; 122331e6b01fSNick Piggin return 0; 1224ef7562d5SAl Viro 1225ef7562d5SAl Viro failed: 1226ef7562d5SAl Viro return -ECHILD; 122731e6b01fSNick Piggin } 122831e6b01fSNick Piggin 12299875cf80SDavid Howells /* 1230cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1231cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1232cc53ce53SDavid Howells * caller is permitted to proceed or not. 1233cc53ce53SDavid Howells */ 12347cc90cc3SAl Viro int follow_down(struct path *path) 1235cc53ce53SDavid Howells { 1236cc53ce53SDavid Howells unsigned managed; 1237cc53ce53SDavid Howells int ret; 1238cc53ce53SDavid Howells 1239cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1240cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1241cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1242cc53ce53SDavid Howells * being held. 1243cc53ce53SDavid Howells * 1244cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1245cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1246cc53ce53SDavid Howells * other than its daemon the right to mount on its 1247cc53ce53SDavid Howells * superstructure. 1248cc53ce53SDavid Howells * 1249cc53ce53SDavid Howells * The filesystem may sleep at this point. 1250cc53ce53SDavid Howells */ 1251cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1252cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1253cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1254ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 12551aed3e42SAl Viro path->dentry, false); 1256cc53ce53SDavid Howells if (ret < 0) 1257cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1258cc53ce53SDavid Howells } 1259cc53ce53SDavid Howells 1260cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1261cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1262cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1263cc53ce53SDavid Howells if (!mounted) 1264cc53ce53SDavid Howells break; 1265cc53ce53SDavid Howells dput(path->dentry); 1266cc53ce53SDavid Howells mntput(path->mnt); 1267cc53ce53SDavid Howells path->mnt = mounted; 1268cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1269cc53ce53SDavid Howells continue; 1270cc53ce53SDavid Howells } 1271cc53ce53SDavid Howells 1272cc53ce53SDavid Howells /* Don't handle automount points here */ 1273cc53ce53SDavid Howells break; 1274cc53ce53SDavid Howells } 1275cc53ce53SDavid Howells return 0; 1276cc53ce53SDavid Howells } 12774d359507SAl Viro EXPORT_SYMBOL(follow_down); 1278cc53ce53SDavid Howells 1279cc53ce53SDavid Howells /* 12809875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 12819875cf80SDavid Howells */ 12829875cf80SDavid Howells static void follow_mount(struct path *path) 12839875cf80SDavid Howells { 12849875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 12859875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12869875cf80SDavid Howells if (!mounted) 12879875cf80SDavid Howells break; 12889875cf80SDavid Howells dput(path->dentry); 12899875cf80SDavid Howells mntput(path->mnt); 12909875cf80SDavid Howells path->mnt = mounted; 12919875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 12929875cf80SDavid Howells } 12939875cf80SDavid Howells } 12949875cf80SDavid Howells 129531e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 12961da177e4SLinus Torvalds { 12977bd88377SAl Viro if (!nd->root.mnt) 12982a737871SAl Viro set_root(nd); 1299e518ddb7SAndreas Mohr 13001da177e4SLinus Torvalds while(1) { 13014ac91378SJan Blunck struct dentry *old = nd->path.dentry; 13021da177e4SLinus Torvalds 13032a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 13042a737871SAl Viro nd->path.mnt == nd->root.mnt) { 13051da177e4SLinus Torvalds break; 13061da177e4SLinus Torvalds } 13074ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 13083088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 13093088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 13101da177e4SLinus Torvalds dput(old); 13111da177e4SLinus Torvalds break; 13121da177e4SLinus Torvalds } 13133088dd70SAl Viro if (!follow_up(&nd->path)) 13141da177e4SLinus Torvalds break; 13151da177e4SLinus Torvalds } 131679ed0226SAl Viro follow_mount(&nd->path); 131731e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 13181da177e4SLinus Torvalds } 13191da177e4SLinus Torvalds 13201da177e4SLinus Torvalds /* 1321bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1322bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1323bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1324bad61189SMiklos Szeredi * 1325bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1326baa03890SNick Piggin */ 1327bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1328201f956eSAl Viro unsigned int flags, bool *need_lookup) 1329baa03890SNick Piggin { 1330baa03890SNick Piggin struct dentry *dentry; 1331bad61189SMiklos Szeredi int error; 1332baa03890SNick Piggin 1333bad61189SMiklos Szeredi *need_lookup = false; 1334bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1335bad61189SMiklos Szeredi if (dentry) { 133639e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1337201f956eSAl Viro error = d_revalidate(dentry, flags); 1338bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1339bad61189SMiklos Szeredi if (error < 0) { 1340bad61189SMiklos Szeredi dput(dentry); 1341bad61189SMiklos Szeredi return ERR_PTR(error); 13425542aa2fSEric W. Biederman } else { 13435542aa2fSEric W. Biederman d_invalidate(dentry); 1344bad61189SMiklos Szeredi dput(dentry); 1345bad61189SMiklos Szeredi dentry = NULL; 1346bad61189SMiklos Szeredi } 1347bad61189SMiklos Szeredi } 1348bad61189SMiklos Szeredi } 1349bad61189SMiklos Szeredi } 1350baa03890SNick Piggin 1351bad61189SMiklos Szeredi if (!dentry) { 1352bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1353baa03890SNick Piggin if (unlikely(!dentry)) 1354baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1355baa03890SNick Piggin 1356bad61189SMiklos Szeredi *need_lookup = true; 1357baa03890SNick Piggin } 1358baa03890SNick Piggin return dentry; 1359baa03890SNick Piggin } 1360baa03890SNick Piggin 1361baa03890SNick Piggin /* 136213a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 136313a2c3beSJ. Bruce Fields * unhashed. 1364bad61189SMiklos Szeredi * 1365bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 136644396f4bSJosef Bacik */ 1367bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 136872bd866aSAl Viro unsigned int flags) 136944396f4bSJosef Bacik { 137044396f4bSJosef Bacik struct dentry *old; 137144396f4bSJosef Bacik 137244396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1373bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1374e188dc02SMiklos Szeredi dput(dentry); 137544396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1376e188dc02SMiklos Szeredi } 137744396f4bSJosef Bacik 137872bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 137944396f4bSJosef Bacik if (unlikely(old)) { 138044396f4bSJosef Bacik dput(dentry); 138144396f4bSJosef Bacik dentry = old; 138244396f4bSJosef Bacik } 138344396f4bSJosef Bacik return dentry; 138444396f4bSJosef Bacik } 138544396f4bSJosef Bacik 1386a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 138772bd866aSAl Viro struct dentry *base, unsigned int flags) 1388a3255546SAl Viro { 1389bad61189SMiklos Szeredi bool need_lookup; 1390a3255546SAl Viro struct dentry *dentry; 1391a3255546SAl Viro 139272bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1393bad61189SMiklos Szeredi if (!need_lookup) 1394a3255546SAl Viro return dentry; 1395bad61189SMiklos Szeredi 139672bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1397a3255546SAl Viro } 1398a3255546SAl Viro 139944396f4bSJosef Bacik /* 14001da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 14011da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 14021da177e4SLinus Torvalds * It _is_ time-critical. 14031da177e4SLinus Torvalds */ 1404e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 140531e6b01fSNick Piggin struct path *path, struct inode **inode) 14061da177e4SLinus Torvalds { 14074ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 140831e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 14095a18fff2SAl Viro int need_reval = 1; 14105a18fff2SAl Viro int status = 1; 14119875cf80SDavid Howells int err; 14129875cf80SDavid Howells 14133cac260aSAl Viro /* 1414b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1415b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1416b04f784eSNick Piggin * do the non-racy lookup, below. 1417b04f784eSNick Piggin */ 141831e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 141931e6b01fSNick Piggin unsigned seq; 1420766c4cbfSAl Viro bool negative; 1421da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 14225a18fff2SAl Viro if (!dentry) 14235a18fff2SAl Viro goto unlazy; 14245a18fff2SAl Viro 142512f8ad4bSLinus Torvalds /* 142612f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 142712f8ad4bSLinus Torvalds * the dentry name information from lookup. 142812f8ad4bSLinus Torvalds */ 142912f8ad4bSLinus Torvalds *inode = dentry->d_inode; 1430766c4cbfSAl Viro negative = d_is_negative(dentry); 143112f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 143212f8ad4bSLinus Torvalds return -ECHILD; 1433766c4cbfSAl Viro if (negative) 1434766c4cbfSAl Viro return -ENOENT; 143512f8ad4bSLinus Torvalds 143612f8ad4bSLinus Torvalds /* 143712f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 143812f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 143912f8ad4bSLinus Torvalds * 144012f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 144112f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 144212f8ad4bSLinus Torvalds */ 144331e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 144431e6b01fSNick Piggin return -ECHILD; 144531e6b01fSNick Piggin nd->seq = seq; 14465a18fff2SAl Viro 144724643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 14484ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14495a18fff2SAl Viro if (unlikely(status <= 0)) { 14505a18fff2SAl Viro if (status != -ECHILD) 14515a18fff2SAl Viro need_reval = 0; 14525a18fff2SAl Viro goto unlazy; 14535a18fff2SAl Viro } 145424643087SAl Viro } 145531e6b01fSNick Piggin path->mnt = mnt; 145631e6b01fSNick Piggin path->dentry = dentry; 1457b8faf035SNeilBrown if (likely(__follow_mount_rcu(nd, path, inode))) 14589875cf80SDavid Howells return 0; 14595a18fff2SAl Viro unlazy: 146019660af7SAl Viro if (unlazy_walk(nd, dentry)) 14615a18fff2SAl Viro return -ECHILD; 14625a18fff2SAl Viro } else { 1463e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 146424643087SAl Viro } 14655a18fff2SAl Viro 146681e6f520SAl Viro if (unlikely(!dentry)) 146781e6f520SAl Viro goto need_lookup; 14685a18fff2SAl Viro 14695a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 14704ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14715a18fff2SAl Viro if (unlikely(status <= 0)) { 14725a18fff2SAl Viro if (status < 0) { 14735a18fff2SAl Viro dput(dentry); 14745a18fff2SAl Viro return status; 14755a18fff2SAl Viro } 14765542aa2fSEric W. Biederman d_invalidate(dentry); 14775a18fff2SAl Viro dput(dentry); 147881e6f520SAl Viro goto need_lookup; 14795a18fff2SAl Viro } 1480697f514dSMiklos Szeredi 1481766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1482766c4cbfSAl Viro dput(dentry); 1483766c4cbfSAl Viro return -ENOENT; 1484766c4cbfSAl Viro } 14851da177e4SLinus Torvalds path->mnt = mnt; 14861da177e4SLinus Torvalds path->dentry = dentry; 1487756daf26SNeilBrown err = follow_managed(path, nd); 14888402752eSAl Viro if (likely(!err)) 148931e6b01fSNick Piggin *inode = path->dentry->d_inode; 14908402752eSAl Viro return err; 149181e6f520SAl Viro 149281e6f520SAl Viro need_lookup: 1493697f514dSMiklos Szeredi return 1; 1494697f514dSMiklos Szeredi } 1495697f514dSMiklos Szeredi 1496697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1497cc2a5271SAl Viro static int lookup_slow(struct nameidata *nd, struct path *path) 1498697f514dSMiklos Szeredi { 1499697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1500697f514dSMiklos Szeredi 1501697f514dSMiklos Szeredi parent = nd->path.dentry; 150281e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 150381e6f520SAl Viro 150481e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 1505cc2a5271SAl Viro dentry = __lookup_hash(&nd->last, parent, nd->flags); 150681e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 150781e6f520SAl Viro if (IS_ERR(dentry)) 150881e6f520SAl Viro return PTR_ERR(dentry); 1509697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1510697f514dSMiklos Szeredi path->dentry = dentry; 15118402752eSAl Viro return follow_managed(path, nd); 15121da177e4SLinus Torvalds } 15131da177e4SLinus Torvalds 151452094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 151552094c8aSAl Viro { 151652094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 15174ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 151852094c8aSAl Viro if (err != -ECHILD) 151952094c8aSAl Viro return err; 152019660af7SAl Viro if (unlazy_walk(nd, NULL)) 152152094c8aSAl Viro return -ECHILD; 152252094c8aSAl Viro } 15234ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 152452094c8aSAl Viro } 152552094c8aSAl Viro 15269856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 15279856fa1bSAl Viro { 15289856fa1bSAl Viro if (type == LAST_DOTDOT) { 15299856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 153070291aecSAl Viro return follow_dotdot_rcu(nd); 15319856fa1bSAl Viro } else 15329856fa1bSAl Viro follow_dotdot(nd); 15339856fa1bSAl Viro } 15349856fa1bSAl Viro return 0; 15359856fa1bSAl Viro } 15369856fa1bSAl Viro 1537951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1538951361f9SAl Viro { 1539951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1540951361f9SAl Viro path_put(&nd->path); 1541951361f9SAl Viro } else { 1542951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 15435b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1544951361f9SAl Viro nd->root.mnt = NULL; 15458b61e74fSAl Viro rcu_read_unlock(); 1546951361f9SAl Viro } 154715439726SAl Viro while (unlikely(nd->depth)) 154815439726SAl Viro put_link(nd); 1549951361f9SAl Viro } 1550951361f9SAl Viro 1551d63ff28fSAl Viro static int pick_link(struct nameidata *nd, struct path *link) 1552d63ff28fSAl Viro { 1553626de996SAl Viro int error; 15541cf2665bSAl Viro struct saved *last; 1555756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1556626de996SAl Viro path_to_nameidata(link, nd); 1557626de996SAl Viro return -ELOOP; 1558626de996SAl Viro } 1559d63ff28fSAl Viro if (nd->flags & LOOKUP_RCU) { 1560d63ff28fSAl Viro if (unlikely(nd->path.mnt != link->mnt || 1561d63ff28fSAl Viro unlazy_walk(nd, link->dentry))) { 1562d63ff28fSAl Viro return -ECHILD; 1563d63ff28fSAl Viro } 1564d63ff28fSAl Viro } 1565cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1566cd179f44SAl Viro mntget(link->mnt); 1567626de996SAl Viro error = nd_alloc_stack(nd); 1568626de996SAl Viro if (unlikely(error)) { 1569cd179f44SAl Viro path_put(link); 1570626de996SAl Viro return error; 1571626de996SAl Viro } 1572626de996SAl Viro 1573ab104923SAl Viro last = nd->stack + nd->depth++; 15741cf2665bSAl Viro last->link = *link; 1575ab104923SAl Viro last->cookie = NULL; 1576d63ff28fSAl Viro return 1; 1577d63ff28fSAl Viro } 1578d63ff28fSAl Viro 15793ddcd056SLinus Torvalds /* 15803ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 15813ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 15823ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 15833ddcd056SLinus Torvalds * for the common case. 15843ddcd056SLinus Torvalds */ 1585d63ff28fSAl Viro static inline int should_follow_link(struct nameidata *nd, struct path *link, int follow) 15863ddcd056SLinus Torvalds { 1587d63ff28fSAl Viro if (likely(!d_is_symlink(link->dentry))) 1588d63ff28fSAl Viro return 0; 1589d63ff28fSAl Viro if (!follow) 1590d63ff28fSAl Viro return 0; 1591d63ff28fSAl Viro return pick_link(nd, link); 15923ddcd056SLinus Torvalds } 15933ddcd056SLinus Torvalds 15944693a547SAl Viro enum {WALK_GET = 1, WALK_PUT = 2}; 15954693a547SAl Viro 15964693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1597ce57dfc1SAl Viro { 1598caa85634SAl Viro struct path path; 1599ce57dfc1SAl Viro struct inode *inode; 1600ce57dfc1SAl Viro int err; 1601ce57dfc1SAl Viro /* 1602ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1603ce57dfc1SAl Viro * to be able to know about the current root directory and 1604ce57dfc1SAl Viro * parent relationships. 1605ce57dfc1SAl Viro */ 16064693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 16074693a547SAl Viro err = handle_dots(nd, nd->last_type); 16084693a547SAl Viro if (flags & WALK_PUT) 16094693a547SAl Viro put_link(nd); 16104693a547SAl Viro return err; 16114693a547SAl Viro } 1612caa85634SAl Viro err = lookup_fast(nd, &path, &inode); 1613ce57dfc1SAl Viro if (unlikely(err)) { 1614697f514dSMiklos Szeredi if (err < 0) 1615f0a9ba70SAl Viro return err; 1616697f514dSMiklos Szeredi 1617caa85634SAl Viro err = lookup_slow(nd, &path); 1618697f514dSMiklos Szeredi if (err < 0) 1619f0a9ba70SAl Viro return err; 1620697f514dSMiklos Szeredi 1621caa85634SAl Viro inode = path.dentry->d_inode; 1622697f514dSMiklos Szeredi err = -ENOENT; 1623caa85634SAl Viro if (d_is_negative(path.dentry)) 1624697f514dSMiklos Szeredi goto out_path_put; 1625766c4cbfSAl Viro } 1626697f514dSMiklos Szeredi 16274693a547SAl Viro if (flags & WALK_PUT) 16284693a547SAl Viro put_link(nd); 1629d63ff28fSAl Viro err = should_follow_link(nd, &path, flags & WALK_GET); 1630d63ff28fSAl Viro if (unlikely(err)) 1631d63ff28fSAl Viro return err; 1632caa85634SAl Viro path_to_nameidata(&path, nd); 1633ce57dfc1SAl Viro nd->inode = inode; 1634ce57dfc1SAl Viro return 0; 1635697f514dSMiklos Szeredi 1636697f514dSMiklos Szeredi out_path_put: 1637caa85634SAl Viro path_to_nameidata(&path, nd); 1638697f514dSMiklos Szeredi return err; 1639ce57dfc1SAl Viro } 1640ce57dfc1SAl Viro 16411da177e4SLinus Torvalds /* 1642bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1643bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1644bfcfaa77SLinus Torvalds * 1645bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1646bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1647bfcfaa77SLinus Torvalds * fast. 1648bfcfaa77SLinus Torvalds * 1649bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1650bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1651bfcfaa77SLinus Torvalds * crossing operation. 1652bfcfaa77SLinus Torvalds * 1653bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1654bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1655bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1656bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1657bfcfaa77SLinus Torvalds */ 1658bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1659bfcfaa77SLinus Torvalds 1660f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1661bfcfaa77SLinus Torvalds 1662f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1663bfcfaa77SLinus Torvalds 1664bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1665bfcfaa77SLinus Torvalds { 166699d263d4SLinus Torvalds return hash_64(hash, 32); 1667bfcfaa77SLinus Torvalds } 1668bfcfaa77SLinus Torvalds 1669bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1670bfcfaa77SLinus Torvalds 1671bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1672bfcfaa77SLinus Torvalds 1673bfcfaa77SLinus Torvalds #endif 1674bfcfaa77SLinus Torvalds 1675bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1676bfcfaa77SLinus Torvalds { 1677bfcfaa77SLinus Torvalds unsigned long a, mask; 1678bfcfaa77SLinus Torvalds unsigned long hash = 0; 1679bfcfaa77SLinus Torvalds 1680bfcfaa77SLinus Torvalds for (;;) { 1681e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1682bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1683bfcfaa77SLinus Torvalds break; 1684bfcfaa77SLinus Torvalds hash += a; 1685f132c5beSAl Viro hash *= 9; 1686bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1687bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1688bfcfaa77SLinus Torvalds if (!len) 1689bfcfaa77SLinus Torvalds goto done; 1690bfcfaa77SLinus Torvalds } 1691a5c21dceSWill Deacon mask = bytemask_from_count(len); 1692bfcfaa77SLinus Torvalds hash += mask & a; 1693bfcfaa77SLinus Torvalds done: 1694bfcfaa77SLinus Torvalds return fold_hash(hash); 1695bfcfaa77SLinus Torvalds } 1696bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1697bfcfaa77SLinus Torvalds 1698bfcfaa77SLinus Torvalds /* 1699bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1700d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1701bfcfaa77SLinus Torvalds */ 1702d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1703bfcfaa77SLinus Torvalds { 170436126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 170536126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1706bfcfaa77SLinus Torvalds 1707bfcfaa77SLinus Torvalds hash = a = 0; 1708bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1709bfcfaa77SLinus Torvalds do { 1710bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1711bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1712e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 171336126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 171436126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1715bfcfaa77SLinus Torvalds 171636126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 171736126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 171836126f8fSLinus Torvalds 171936126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 172036126f8fSLinus Torvalds 172136126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 17229226b5b4SLinus Torvalds len += find_zero(mask); 1723d6bb3e90SLinus Torvalds return hashlen_create(fold_hash(hash), len); 1724bfcfaa77SLinus Torvalds } 1725bfcfaa77SLinus Torvalds 1726bfcfaa77SLinus Torvalds #else 1727bfcfaa77SLinus Torvalds 17280145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 17290145acc2SLinus Torvalds { 17300145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 17310145acc2SLinus Torvalds while (len--) 17320145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 17330145acc2SLinus Torvalds return end_name_hash(hash); 17340145acc2SLinus Torvalds } 1735ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 17360145acc2SLinus Torvalds 17373ddcd056SLinus Torvalds /* 1738200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1739200e9ef7SLinus Torvalds * one character. 1740200e9ef7SLinus Torvalds */ 1741d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1742200e9ef7SLinus Torvalds { 1743200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1744200e9ef7SLinus Torvalds unsigned long len = 0, c; 1745200e9ef7SLinus Torvalds 1746200e9ef7SLinus Torvalds c = (unsigned char)*name; 1747200e9ef7SLinus Torvalds do { 1748200e9ef7SLinus Torvalds len++; 1749200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1750200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1751200e9ef7SLinus Torvalds } while (c && c != '/'); 1752d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 1753200e9ef7SLinus Torvalds } 1754200e9ef7SLinus Torvalds 1755bfcfaa77SLinus Torvalds #endif 1756bfcfaa77SLinus Torvalds 1757200e9ef7SLinus Torvalds /* 17581da177e4SLinus Torvalds * Name resolution. 1759ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1760ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 17611da177e4SLinus Torvalds * 1762ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1763ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 17641da177e4SLinus Torvalds */ 17656de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 17661da177e4SLinus Torvalds { 17671da177e4SLinus Torvalds int err; 17681da177e4SLinus Torvalds 17691da177e4SLinus Torvalds while (*name=='/') 17701da177e4SLinus Torvalds name++; 17711da177e4SLinus Torvalds if (!*name) 17729e18f10aSAl Viro return 0; 17731da177e4SLinus Torvalds 17741da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 17751da177e4SLinus Torvalds for(;;) { 1776d6bb3e90SLinus Torvalds u64 hash_len; 1777fe479a58SAl Viro int type; 17781da177e4SLinus Torvalds 177952094c8aSAl Viro err = may_lookup(nd); 17801da177e4SLinus Torvalds if (err) 17811da177e4SLinus Torvalds break; 17821da177e4SLinus Torvalds 1783d6bb3e90SLinus Torvalds hash_len = hash_name(name); 17841da177e4SLinus Torvalds 1785fe479a58SAl Viro type = LAST_NORM; 1786d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 1787fe479a58SAl Viro case 2: 1788200e9ef7SLinus Torvalds if (name[1] == '.') { 1789fe479a58SAl Viro type = LAST_DOTDOT; 179016c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 179116c2cd71SAl Viro } 1792fe479a58SAl Viro break; 1793fe479a58SAl Viro case 1: 1794fe479a58SAl Viro type = LAST_DOT; 1795fe479a58SAl Viro } 17965a202bcdSAl Viro if (likely(type == LAST_NORM)) { 17975a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 179816c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 17995a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 1800a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 1801da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 18025a202bcdSAl Viro if (err < 0) 18035a202bcdSAl Viro break; 1804d6bb3e90SLinus Torvalds hash_len = this.hash_len; 1805d6bb3e90SLinus Torvalds name = this.name; 18065a202bcdSAl Viro } 18075a202bcdSAl Viro } 1808fe479a58SAl Viro 1809d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 1810d6bb3e90SLinus Torvalds nd->last.name = name; 18115f4a6a69SAl Viro nd->last_type = type; 18125f4a6a69SAl Viro 1813d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 1814d6bb3e90SLinus Torvalds if (!*name) 1815bdf6cbf1SAl Viro goto OK; 1816200e9ef7SLinus Torvalds /* 1817200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1818200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1819200e9ef7SLinus Torvalds */ 1820200e9ef7SLinus Torvalds do { 1821d6bb3e90SLinus Torvalds name++; 1822d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 18238620c238SAl Viro if (unlikely(!*name)) { 18248620c238SAl Viro OK: 18258620c238SAl Viro /* called from path_init(), done */ 18268620c238SAl Viro if (!nd->depth) 18278620c238SAl Viro return 0; 18288620c238SAl Viro name = nd->stack[nd->depth - 1].name; 18298620c238SAl Viro /* called from trailing_symlink(), done */ 18308620c238SAl Viro if (!name) 18318620c238SAl Viro return 0; 18328620c238SAl Viro /* last component of nested symlink */ 18334693a547SAl Viro err = walk_component(nd, WALK_GET | WALK_PUT); 18348620c238SAl Viro } else { 18354693a547SAl Viro err = walk_component(nd, WALK_GET); 18368620c238SAl Viro } 1837ce57dfc1SAl Viro if (err < 0) 1838f0a9ba70SAl Viro break; 1839fe479a58SAl Viro 1840ce57dfc1SAl Viro if (err) { 1841626de996SAl Viro const char *s = get_link(nd); 18425a460275SAl Viro 1843172a39a0SAl Viro if (unlikely(IS_ERR(s))) { 1844172a39a0SAl Viro err = PTR_ERR(s); 18451bc4b813SAl Viro break; 1846172a39a0SAl Viro } 1847172a39a0SAl Viro err = 0; 184812b09578SAl Viro if (unlikely(!s)) { 184912b09578SAl Viro /* jumped */ 1850b9ff4429SAl Viro put_link(nd); 185112b09578SAl Viro } else { 1852071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 185332cd7468SAl Viro name = s; 18549e18f10aSAl Viro continue; 185548c8b0c5SAl Viro } 185631e6b01fSNick Piggin } 185744b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 18583ddcd056SLinus Torvalds err = -ENOTDIR; 18593ddcd056SLinus Torvalds break; 18605f4a6a69SAl Viro } 1861ce57dfc1SAl Viro } 1862951361f9SAl Viro terminate_walk(nd); 18631da177e4SLinus Torvalds return err; 186407681481SAl Viro } 18651da177e4SLinus Torvalds 18666e8a1f87SAl Viro static int path_init(int dfd, const struct filename *name, unsigned int flags, 18675e53084dSAl Viro struct nameidata *nd) 186831e6b01fSNick Piggin { 186931e6b01fSNick Piggin int retval = 0; 1870fd2f7cb5SAl Viro const char *s = name->name; 187131e6b01fSNick Piggin 187231e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 1873980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 187431e6b01fSNick Piggin nd->depth = 0; 18755e53084dSAl Viro nd->base = NULL; 18765b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 1877b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 1878b18825a7SDavid Howells struct inode *inode = root->d_inode; 1879fd2f7cb5SAl Viro if (*s) { 188044b1d530SMiklos Szeredi if (!d_can_lookup(root)) 18815b6ca027SAl Viro return -ENOTDIR; 18825b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 18835b6ca027SAl Viro if (retval) 18845b6ca027SAl Viro return retval; 188573d049a4SAl Viro } 18865b6ca027SAl Viro nd->path = nd->root; 18875b6ca027SAl Viro nd->inode = inode; 18885b6ca027SAl Viro if (flags & LOOKUP_RCU) { 18898b61e74fSAl Viro rcu_read_lock(); 18905b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 189148a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 18925b6ca027SAl Viro } else { 18935b6ca027SAl Viro path_get(&nd->path); 18945b6ca027SAl Viro } 1895d465887fSAl Viro goto done; 18965b6ca027SAl Viro } 18975b6ca027SAl Viro 189831e6b01fSNick Piggin nd->root.mnt = NULL; 189931e6b01fSNick Piggin 190048a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 1901fd2f7cb5SAl Viro if (*s == '/') { 1902e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 19038b61e74fSAl Viro rcu_read_lock(); 19047bd88377SAl Viro nd->seq = set_root_rcu(nd); 1905e41f7d4eSAl Viro } else { 1906e41f7d4eSAl Viro set_root(nd); 1907e41f7d4eSAl Viro path_get(&nd->root); 1908e41f7d4eSAl Viro } 190931e6b01fSNick Piggin nd->path = nd->root; 191031e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1911e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 191231e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1913c28cc364SNick Piggin unsigned seq; 191431e6b01fSNick Piggin 19158b61e74fSAl Viro rcu_read_lock(); 191631e6b01fSNick Piggin 1917c28cc364SNick Piggin do { 1918c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 191931e6b01fSNick Piggin nd->path = fs->pwd; 1920c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1921c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1922e41f7d4eSAl Viro } else { 1923e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1924e41f7d4eSAl Viro } 192531e6b01fSNick Piggin } else { 1926582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 19272903ff01SAl Viro struct fd f = fdget_raw(dfd); 192831e6b01fSNick Piggin struct dentry *dentry; 192931e6b01fSNick Piggin 19302903ff01SAl Viro if (!f.file) 19312903ff01SAl Viro return -EBADF; 193231e6b01fSNick Piggin 19332903ff01SAl Viro dentry = f.file->f_path.dentry; 193431e6b01fSNick Piggin 1935fd2f7cb5SAl Viro if (*s) { 193644b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 19372903ff01SAl Viro fdput(f); 19382903ff01SAl Viro return -ENOTDIR; 1939f52e0c11SAl Viro } 19402903ff01SAl Viro } 19412903ff01SAl Viro 19422903ff01SAl Viro nd->path = f.file->f_path; 1943e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 19449c225f26SLinus Torvalds if (f.flags & FDPUT_FPUT) 19455e53084dSAl Viro nd->base = f.file; 1946c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 19478b61e74fSAl Viro rcu_read_lock(); 19485590ff0dSUlrich Drepper } else { 19492903ff01SAl Viro path_get(&nd->path); 19502903ff01SAl Viro fdput(f); 19511da177e4SLinus Torvalds } 1952e41f7d4eSAl Viro } 1953e41f7d4eSAl Viro 195431e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 19554023bfc9SAl Viro if (!(flags & LOOKUP_RCU)) 1956d465887fSAl Viro goto done; 19574023bfc9SAl Viro if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) 1958d465887fSAl Viro goto done; 19594023bfc9SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 19604023bfc9SAl Viro nd->root.mnt = NULL; 19614023bfc9SAl Viro rcu_read_unlock(); 19624023bfc9SAl Viro return -ECHILD; 1963d465887fSAl Viro done: 1964756daf26SNeilBrown nd->total_link_count = 0; 1965dc7af8dcSAl Viro return link_path_walk(s, nd); 19669b4a9b14SAl Viro } 19679b4a9b14SAl Viro 1968893b7775SAl Viro static void path_cleanup(struct nameidata *nd) 1969893b7775SAl Viro { 1970893b7775SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 1971893b7775SAl Viro path_put(&nd->root); 1972893b7775SAl Viro nd->root.mnt = NULL; 1973893b7775SAl Viro } 1974893b7775SAl Viro if (unlikely(nd->base)) 1975893b7775SAl Viro fput(nd->base); 19769b4a9b14SAl Viro } 19779b4a9b14SAl Viro 19781d8e03d3SAl Viro static int trailing_symlink(struct nameidata *nd) 197995fa25d9SAl Viro { 198095fa25d9SAl Viro const char *s; 1981fec2fa24SAl Viro int error = may_follow_link(nd); 1982b5cd3397SAl Viro if (unlikely(error)) { 1983b5cd3397SAl Viro terminate_walk(nd); 198495fa25d9SAl Viro return error; 1985b5cd3397SAl Viro } 198695fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 1987fab51e8aSAl Viro nd->stack[0].name = NULL; 19883b2e7f75SAl Viro s = get_link(nd); 19891bc4b813SAl Viro if (unlikely(IS_ERR(s))) { 19901bc4b813SAl Viro terminate_walk(nd); 199195fa25d9SAl Viro return PTR_ERR(s); 19921bc4b813SAl Viro } 19939ea57b72SAl Viro if (unlikely(!s)) 199495fa25d9SAl Viro return 0; 19958eff733aSAl Viro return link_path_walk(s, nd); 199695fa25d9SAl Viro } 199795fa25d9SAl Viro 1998caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 1999bd92d7feSAl Viro { 2000f0a9ba70SAl Viro int err; 2001bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2002bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2003bd92d7feSAl Viro 2004bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 20054693a547SAl Viro err = walk_component(nd, 20064693a547SAl Viro nd->flags & LOOKUP_FOLLOW 20074693a547SAl Viro ? nd->depth 20084693a547SAl Viro ? WALK_PUT | WALK_GET 20094693a547SAl Viro : WALK_GET 20104693a547SAl Viro : 0); 2011f0a9ba70SAl Viro if (err < 0) 2012f0a9ba70SAl Viro terminate_walk(nd); 2013f0a9ba70SAl Viro return err; 2014bd92d7feSAl Viro } 2015bd92d7feSAl Viro 20169b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 20175eb6b495SAl Viro static int path_lookupat(int dfd, const struct filename *name, 20189b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 20199b4a9b14SAl Viro { 2020bd92d7feSAl Viro int err; 202131e6b01fSNick Piggin 202231e6b01fSNick Piggin /* 202331e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 202431e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 202531e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 202631e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 202731e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 202831e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 202931e6b01fSNick Piggin * analogue, foo_rcu(). 203031e6b01fSNick Piggin * 203131e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 203231e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 203331e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 203431e6b01fSNick Piggin * be able to complete). 203531e6b01fSNick Piggin */ 20366e8a1f87SAl Viro err = path_init(dfd, name, flags, nd); 20378bcb77faSAl Viro if (!err) { 2038191d7f73SAl Viro while ((err = lookup_last(nd)) > 0) { 20391d8e03d3SAl Viro err = trailing_symlink(nd); 20406d7b5aaeSAl Viro if (err) 20416d7b5aaeSAl Viro break; 2042bd92d7feSAl Viro } 2043bd92d7feSAl Viro } 2044ee0827cdSAl Viro 20459f1fafeeSAl Viro if (!err) 20469f1fafeeSAl Viro err = complete_walk(nd); 2047bd92d7feSAl Viro 2048bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 204944b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 2050bd92d7feSAl Viro path_put(&nd->path); 2051bd23a539SAl Viro err = -ENOTDIR; 2052bd92d7feSAl Viro } 2053bd92d7feSAl Viro } 205416c2cd71SAl Viro 2055893b7775SAl Viro path_cleanup(nd); 2056bd92d7feSAl Viro return err; 205731e6b01fSNick Piggin } 205831e6b01fSNick Piggin 2059873f1eedSJeff Layton static int filename_lookup(int dfd, struct filename *name, 2060873f1eedSJeff Layton unsigned int flags, struct nameidata *nd) 2061873f1eedSJeff Layton { 2062894bc8c4SAl Viro int retval; 2063756daf26SNeilBrown struct nameidata *saved_nd = set_nameidata(nd); 2064894bc8c4SAl Viro 2065894bc8c4SAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 2066873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 20675eb6b495SAl Viro retval = path_lookupat(dfd, name, flags, nd); 2068873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 20695eb6b495SAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 2070873f1eedSJeff Layton 2071873f1eedSJeff Layton if (likely(!retval)) 2072adb5c247SJeff Layton audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); 2073756daf26SNeilBrown restore_nameidata(saved_nd); 2074873f1eedSJeff Layton return retval; 2075873f1eedSJeff Layton } 2076873f1eedSJeff Layton 20778bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 20788bcb77faSAl Viro static int path_parentat(int dfd, const struct filename *name, 20798bcb77faSAl Viro unsigned int flags, struct nameidata *nd) 20808bcb77faSAl Viro { 20818bcb77faSAl Viro int err = path_init(dfd, name, flags | LOOKUP_PARENT, nd); 20828bcb77faSAl Viro if (!err) 20838bcb77faSAl Viro err = complete_walk(nd); 20848bcb77faSAl Viro path_cleanup(nd); 20858bcb77faSAl Viro return err; 20868bcb77faSAl Viro } 20878bcb77faSAl Viro 20888bcb77faSAl Viro static int filename_parentat(int dfd, struct filename *name, 20898bcb77faSAl Viro unsigned int flags, struct nameidata *nd) 20908bcb77faSAl Viro { 20918bcb77faSAl Viro int retval; 20928bcb77faSAl Viro struct nameidata *saved_nd = set_nameidata(nd); 20938bcb77faSAl Viro 20948bcb77faSAl Viro retval = path_parentat(dfd, name, flags | LOOKUP_RCU, nd); 20958bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 20968bcb77faSAl Viro retval = path_parentat(dfd, name, flags, nd); 20978bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 20988bcb77faSAl Viro retval = path_parentat(dfd, name, flags | LOOKUP_REVAL, nd); 20998bcb77faSAl Viro 21008bcb77faSAl Viro if (likely(!retval)) 21018bcb77faSAl Viro audit_inode(name, nd->path.dentry, LOOKUP_PARENT); 21028bcb77faSAl Viro restore_nameidata(saved_nd); 21038bcb77faSAl Viro return retval; 21048bcb77faSAl Viro } 21058bcb77faSAl Viro 210679714f72SAl Viro /* does lookup, returns the object with parent locked */ 210779714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 21085590ff0dSUlrich Drepper { 210951689104SPaul Moore struct filename *filename = getname_kernel(name); 211079714f72SAl Viro struct nameidata nd; 211179714f72SAl Viro struct dentry *d; 211251689104SPaul Moore int err; 211351689104SPaul Moore 211451689104SPaul Moore if (IS_ERR(filename)) 211551689104SPaul Moore return ERR_CAST(filename); 211651689104SPaul Moore 21178bcb77faSAl Viro err = filename_parentat(AT_FDCWD, filename, 0, &nd); 211851689104SPaul Moore if (err) { 211951689104SPaul Moore d = ERR_PTR(err); 212051689104SPaul Moore goto out; 212151689104SPaul Moore } 212279714f72SAl Viro if (nd.last_type != LAST_NORM) { 212379714f72SAl Viro path_put(&nd.path); 212451689104SPaul Moore d = ERR_PTR(-EINVAL); 212551689104SPaul Moore goto out; 212679714f72SAl Viro } 212779714f72SAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 21281e0ea001SAl Viro d = __lookup_hash(&nd.last, nd.path.dentry, 0); 212979714f72SAl Viro if (IS_ERR(d)) { 213079714f72SAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 213179714f72SAl Viro path_put(&nd.path); 213251689104SPaul Moore goto out; 213379714f72SAl Viro } 213479714f72SAl Viro *path = nd.path; 213551689104SPaul Moore out: 213651689104SPaul Moore putname(filename); 213779714f72SAl Viro return d; 21385590ff0dSUlrich Drepper } 21395590ff0dSUlrich Drepper 2140d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2141d1811465SAl Viro { 2142d1811465SAl Viro struct nameidata nd; 214374eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 214474eb8cc5SAl Viro int res = PTR_ERR(filename); 214574eb8cc5SAl Viro 214674eb8cc5SAl Viro if (!IS_ERR(filename)) { 214774eb8cc5SAl Viro res = filename_lookup(AT_FDCWD, filename, flags, &nd); 214874eb8cc5SAl Viro putname(filename); 2149d1811465SAl Viro if (!res) 2150d1811465SAl Viro *path = nd.path; 215174eb8cc5SAl Viro } 2152d1811465SAl Viro return res; 2153d1811465SAl Viro } 21544d359507SAl Viro EXPORT_SYMBOL(kern_path); 2155d1811465SAl Viro 215616f18200SJosef 'Jeff' Sipek /** 215716f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 215816f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 215916f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 216016f18200SJosef 'Jeff' Sipek * @name: pointer to file name 216116f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2162e0a01249SAl Viro * @path: pointer to struct path to fill 216316f18200SJosef 'Jeff' Sipek */ 216416f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 216516f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2166e0a01249SAl Viro struct path *path) 216716f18200SJosef 'Jeff' Sipek { 216874eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 216974eb8cc5SAl Viro int err = PTR_ERR(filename); 217074eb8cc5SAl Viro 217174eb8cc5SAl Viro BUG_ON(flags & LOOKUP_PARENT); 217274eb8cc5SAl Viro 217374eb8cc5SAl Viro /* the first argument of filename_lookup() is ignored with LOOKUP_ROOT */ 217474eb8cc5SAl Viro if (!IS_ERR(filename)) { 2175e0a01249SAl Viro struct nameidata nd; 2176e0a01249SAl Viro nd.root.dentry = dentry; 2177e0a01249SAl Viro nd.root.mnt = mnt; 217874eb8cc5SAl Viro err = filename_lookup(AT_FDCWD, filename, 217974eb8cc5SAl Viro flags | LOOKUP_ROOT, &nd); 2180e0a01249SAl Viro if (!err) 2181e0a01249SAl Viro *path = nd.path; 218274eb8cc5SAl Viro putname(filename); 218374eb8cc5SAl Viro } 2184e0a01249SAl Viro return err; 218516f18200SJosef 'Jeff' Sipek } 21864d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 218716f18200SJosef 'Jeff' Sipek 2188eead1911SChristoph Hellwig /** 2189a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2190eead1911SChristoph Hellwig * @name: pathname component to lookup 2191eead1911SChristoph Hellwig * @base: base directory to lookup from 2192eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2193eead1911SChristoph Hellwig * 2194a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 21959e7543e9SAl Viro * not be called by generic code. 2196eead1911SChristoph Hellwig */ 2197057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2198057f6c01SJames Morris { 2199057f6c01SJames Morris struct qstr this; 22006a96ba54SAl Viro unsigned int c; 2201cda309deSMiklos Szeredi int err; 2202057f6c01SJames Morris 22032f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 22042f9092e1SDavid Woodhouse 22056a96ba54SAl Viro this.name = name; 22066a96ba54SAl Viro this.len = len; 22070145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 22086a96ba54SAl Viro if (!len) 22096a96ba54SAl Viro return ERR_PTR(-EACCES); 22106a96ba54SAl Viro 221121d8a15aSAl Viro if (unlikely(name[0] == '.')) { 221221d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 221321d8a15aSAl Viro return ERR_PTR(-EACCES); 221421d8a15aSAl Viro } 221521d8a15aSAl Viro 22166a96ba54SAl Viro while (len--) { 22176a96ba54SAl Viro c = *(const unsigned char *)name++; 22186a96ba54SAl Viro if (c == '/' || c == '\0') 22196a96ba54SAl Viro return ERR_PTR(-EACCES); 22206a96ba54SAl Viro } 22215a202bcdSAl Viro /* 22225a202bcdSAl Viro * See if the low-level filesystem might want 22235a202bcdSAl Viro * to use its own hash.. 22245a202bcdSAl Viro */ 22255a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2226da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 22275a202bcdSAl Viro if (err < 0) 22285a202bcdSAl Viro return ERR_PTR(err); 22295a202bcdSAl Viro } 2230eead1911SChristoph Hellwig 2231cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2232cda309deSMiklos Szeredi if (err) 2233cda309deSMiklos Szeredi return ERR_PTR(err); 2234cda309deSMiklos Szeredi 223572bd866aSAl Viro return __lookup_hash(&this, base, 0); 2236057f6c01SJames Morris } 22374d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2238057f6c01SJames Morris 22391fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 22401fa1e7f6SAndy Whitcroft struct path *path, int *empty) 22411da177e4SLinus Torvalds { 22422d8f3038SAl Viro struct nameidata nd; 224391a27b2aSJeff Layton struct filename *tmp = getname_flags(name, flags, empty); 22441da177e4SLinus Torvalds int err = PTR_ERR(tmp); 22451da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 22462d8f3038SAl Viro 22472d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 22482d8f3038SAl Viro 2249873f1eedSJeff Layton err = filename_lookup(dfd, tmp, flags, &nd); 22501da177e4SLinus Torvalds putname(tmp); 22512d8f3038SAl Viro if (!err) 22522d8f3038SAl Viro *path = nd.path; 22531da177e4SLinus Torvalds } 22541da177e4SLinus Torvalds return err; 22551da177e4SLinus Torvalds } 22561da177e4SLinus Torvalds 22571fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 22581fa1e7f6SAndy Whitcroft struct path *path) 22591fa1e7f6SAndy Whitcroft { 2260f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 22611fa1e7f6SAndy Whitcroft } 22624d359507SAl Viro EXPORT_SYMBOL(user_path_at); 22631fa1e7f6SAndy Whitcroft 2264873f1eedSJeff Layton /* 2265873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2266873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2267873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2268873f1eedSJeff Layton * path-walking is complete. 2269873f1eedSJeff Layton */ 227091a27b2aSJeff Layton static struct filename * 2271f5beed75SAl Viro user_path_parent(int dfd, const char __user *path, 2272f5beed75SAl Viro struct path *parent, 2273f5beed75SAl Viro struct qstr *last, 2274f5beed75SAl Viro int *type, 22759e790bd6SJeff Layton unsigned int flags) 22762ad94ae6SAl Viro { 2277f5beed75SAl Viro struct nameidata nd; 227891a27b2aSJeff Layton struct filename *s = getname(path); 22792ad94ae6SAl Viro int error; 22802ad94ae6SAl Viro 22819e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 22829e790bd6SJeff Layton flags &= LOOKUP_REVAL; 22839e790bd6SJeff Layton 22842ad94ae6SAl Viro if (IS_ERR(s)) 228591a27b2aSJeff Layton return s; 22862ad94ae6SAl Viro 22878bcb77faSAl Viro error = filename_parentat(dfd, s, flags, &nd); 228891a27b2aSJeff Layton if (error) { 22892ad94ae6SAl Viro putname(s); 229091a27b2aSJeff Layton return ERR_PTR(error); 229191a27b2aSJeff Layton } 2292f5beed75SAl Viro *parent = nd.path; 2293f5beed75SAl Viro *last = nd.last; 2294f5beed75SAl Viro *type = nd.last_type; 22952ad94ae6SAl Viro 229691a27b2aSJeff Layton return s; 22972ad94ae6SAl Viro } 22982ad94ae6SAl Viro 22998033426eSJeff Layton /** 2300197df04cSAl Viro * mountpoint_last - look up last component for umount 23018033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 23028033426eSJeff Layton * @path: pointer to container for result 23038033426eSJeff Layton * 23048033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 23058033426eSJeff Layton * need to resolve the path without doing any revalidation. 23068033426eSJeff Layton * 23078033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 23088033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 23098033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 23108033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 23118033426eSJeff Layton * bogus and it doesn't exist. 23128033426eSJeff Layton * 23138033426eSJeff Layton * Returns: 23148033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 23158033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 23168033426eSJeff Layton * put in this case. 23178033426eSJeff Layton * 23188033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 23198033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 23208033426eSJeff Layton * The nd->path reference will also be put. 23218033426eSJeff Layton * 23228033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 23238033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 23248033426eSJeff Layton * to the link, and nd->path will *not* be put. 23258033426eSJeff Layton */ 23268033426eSJeff Layton static int 2327197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 23288033426eSJeff Layton { 23298033426eSJeff Layton int error = 0; 23308033426eSJeff Layton struct dentry *dentry; 23318033426eSJeff Layton struct dentry *dir = nd->path.dentry; 23328033426eSJeff Layton 233335759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 233435759521SAl Viro if (nd->flags & LOOKUP_RCU) { 233535759521SAl Viro if (unlazy_walk(nd, NULL)) { 23368033426eSJeff Layton error = -ECHILD; 233735759521SAl Viro goto out; 233835759521SAl Viro } 23398033426eSJeff Layton } 23408033426eSJeff Layton 23418033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 23428033426eSJeff Layton 23438033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 23448033426eSJeff Layton error = handle_dots(nd, nd->last_type); 234535759521SAl Viro if (error) 234635759521SAl Viro goto out; 23478033426eSJeff Layton dentry = dget(nd->path.dentry); 234835759521SAl Viro goto done; 23498033426eSJeff Layton } 23508033426eSJeff Layton 23518033426eSJeff Layton mutex_lock(&dir->d_inode->i_mutex); 23528033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 23538033426eSJeff Layton if (!dentry) { 23548033426eSJeff Layton /* 23558033426eSJeff Layton * No cached dentry. Mounted dentries are pinned in the cache, 23568033426eSJeff Layton * so that means that this dentry is probably a symlink or the 23578033426eSJeff Layton * path doesn't actually point to a mounted dentry. 23588033426eSJeff Layton */ 23598033426eSJeff Layton dentry = d_alloc(dir, &nd->last); 23608033426eSJeff Layton if (!dentry) { 23618033426eSJeff Layton error = -ENOMEM; 2362bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 236335759521SAl Viro goto out; 23648033426eSJeff Layton } 236535759521SAl Viro dentry = lookup_real(dir->d_inode, dentry, nd->flags); 236635759521SAl Viro error = PTR_ERR(dentry); 2367bcceeebaSDave Jones if (IS_ERR(dentry)) { 2368bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 236935759521SAl Viro goto out; 23708033426eSJeff Layton } 2371bcceeebaSDave Jones } 23728033426eSJeff Layton mutex_unlock(&dir->d_inode->i_mutex); 23738033426eSJeff Layton 237435759521SAl Viro done: 2375698934dfSDavid Howells if (d_is_negative(dentry)) { 23768033426eSJeff Layton error = -ENOENT; 23778033426eSJeff Layton dput(dentry); 237835759521SAl Viro goto out; 237935759521SAl Viro } 2380191d7f73SAl Viro if (nd->depth) 2381191d7f73SAl Viro put_link(nd); 23828033426eSJeff Layton path->dentry = dentry; 2383295dc39dSVasily Averin path->mnt = nd->path.mnt; 2384d63ff28fSAl Viro error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW); 2385d63ff28fSAl Viro if (unlikely(error)) { 2386d63ff28fSAl Viro if (error < 0) 2387d63ff28fSAl Viro goto out; 2388d63ff28fSAl Viro return error; 2389caa85634SAl Viro } 2390295dc39dSVasily Averin mntget(path->mnt); 23918033426eSJeff Layton follow_mount(path); 239235759521SAl Viro error = 0; 239335759521SAl Viro out: 23948033426eSJeff Layton terminate_walk(nd); 23958033426eSJeff Layton return error; 23968033426eSJeff Layton } 23978033426eSJeff Layton 23988033426eSJeff Layton /** 2399197df04cSAl Viro * path_mountpoint - look up a path to be umounted 24008033426eSJeff Layton * @dfd: directory file descriptor to start walk from 24018033426eSJeff Layton * @name: full pathname to walk 2402606d6fe3SRandy Dunlap * @path: pointer to container for result 24038033426eSJeff Layton * @flags: lookup flags 24048033426eSJeff Layton * 24058033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2406606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 24078033426eSJeff Layton */ 24088033426eSJeff Layton static int 2409668696dcSAl Viro path_mountpoint(int dfd, const struct filename *name, struct path *path, 241046afd6f6SAl Viro struct nameidata *nd, unsigned int flags) 24118033426eSJeff Layton { 241246afd6f6SAl Viro int err = path_init(dfd, name, flags, nd); 24138033426eSJeff Layton if (unlikely(err)) 2414115cbfdcSAl Viro goto out; 24158033426eSJeff Layton 2416191d7f73SAl Viro while ((err = mountpoint_last(nd, path)) > 0) { 24171d8e03d3SAl Viro err = trailing_symlink(nd); 24188033426eSJeff Layton if (err) 24198033426eSJeff Layton break; 24208033426eSJeff Layton } 24218033426eSJeff Layton out: 242246afd6f6SAl Viro path_cleanup(nd); 24238033426eSJeff Layton return err; 24248033426eSJeff Layton } 24258033426eSJeff Layton 24262d864651SAl Viro static int 2427668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 24282d864651SAl Viro unsigned int flags) 24292d864651SAl Viro { 2430756daf26SNeilBrown struct nameidata nd, *saved; 2431cbaab2dbSAl Viro int error; 2432668696dcSAl Viro if (IS_ERR(name)) 2433668696dcSAl Viro return PTR_ERR(name); 2434756daf26SNeilBrown saved = set_nameidata(&nd); 243546afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_RCU); 24362d864651SAl Viro if (unlikely(error == -ECHILD)) 243746afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags); 24382d864651SAl Viro if (unlikely(error == -ESTALE)) 243946afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_REVAL); 24402d864651SAl Viro if (likely(!error)) 2441668696dcSAl Viro audit_inode(name, path->dentry, 0); 2442756daf26SNeilBrown restore_nameidata(saved); 2443668696dcSAl Viro putname(name); 24442d864651SAl Viro return error; 24452d864651SAl Viro } 24462d864651SAl Viro 24478033426eSJeff Layton /** 2448197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 24498033426eSJeff Layton * @dfd: directory file descriptor 24508033426eSJeff Layton * @name: pathname from userland 24518033426eSJeff Layton * @flags: lookup flags 24528033426eSJeff Layton * @path: pointer to container to hold result 24538033426eSJeff Layton * 24548033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 24558033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 24568033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 24578033426eSJeff Layton * and avoid revalidating the last component. 24588033426eSJeff Layton * 24598033426eSJeff Layton * Returns 0 and populates "path" on success. 24608033426eSJeff Layton */ 24618033426eSJeff Layton int 2462197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 24638033426eSJeff Layton struct path *path) 24648033426eSJeff Layton { 2465cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 24668033426eSJeff Layton } 24678033426eSJeff Layton 24682d864651SAl Viro int 24692d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 24702d864651SAl Viro unsigned int flags) 24712d864651SAl Viro { 2472cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 24732d864651SAl Viro } 24742d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 24752d864651SAl Viro 2476cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 24771da177e4SLinus Torvalds { 24788e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2479da9592edSDavid Howells 24808e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 24811da177e4SLinus Torvalds return 0; 24828e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 24831da177e4SLinus Torvalds return 0; 248423adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 24851da177e4SLinus Torvalds } 2486cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 24871da177e4SLinus Torvalds 24881da177e4SLinus Torvalds /* 24891da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 24901da177e4SLinus Torvalds * whether the type of victim is right. 24911da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 24921da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 24931da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 24941da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 24951da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 24961da177e4SLinus Torvalds * a. be owner of dir, or 24971da177e4SLinus Torvalds * b. be owner of victim, or 24981da177e4SLinus Torvalds * c. have CAP_FOWNER capability 24991da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 25001da177e4SLinus Torvalds * links pointing to it. 25011da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 25021da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 25031da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 25041da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 25051da177e4SLinus Torvalds * nfs_async_unlink(). 25061da177e4SLinus Torvalds */ 2507b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 25081da177e4SLinus Torvalds { 2509b18825a7SDavid Howells struct inode *inode = victim->d_inode; 25101da177e4SLinus Torvalds int error; 25111da177e4SLinus Torvalds 2512b18825a7SDavid Howells if (d_is_negative(victim)) 25131da177e4SLinus Torvalds return -ENOENT; 2514b18825a7SDavid Howells BUG_ON(!inode); 25151da177e4SLinus Torvalds 25161da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 25174fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 25181da177e4SLinus Torvalds 2519f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 25201da177e4SLinus Torvalds if (error) 25211da177e4SLinus Torvalds return error; 25221da177e4SLinus Torvalds if (IS_APPEND(dir)) 25231da177e4SLinus Torvalds return -EPERM; 2524b18825a7SDavid Howells 2525b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2526b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 25271da177e4SLinus Torvalds return -EPERM; 25281da177e4SLinus Torvalds if (isdir) { 252944b1d530SMiklos Szeredi if (!d_is_dir(victim)) 25301da177e4SLinus Torvalds return -ENOTDIR; 25311da177e4SLinus Torvalds if (IS_ROOT(victim)) 25321da177e4SLinus Torvalds return -EBUSY; 253344b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 25341da177e4SLinus Torvalds return -EISDIR; 25351da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25361da177e4SLinus Torvalds return -ENOENT; 25371da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 25381da177e4SLinus Torvalds return -EBUSY; 25391da177e4SLinus Torvalds return 0; 25401da177e4SLinus Torvalds } 25411da177e4SLinus Torvalds 25421da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 25431da177e4SLinus Torvalds * dir. 25441da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 25451da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 25461da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 25471da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 25481da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 25491da177e4SLinus Torvalds */ 2550a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 25511da177e4SLinus Torvalds { 255214e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 25531da177e4SLinus Torvalds if (child->d_inode) 25541da177e4SLinus Torvalds return -EEXIST; 25551da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25561da177e4SLinus Torvalds return -ENOENT; 2557f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 25581da177e4SLinus Torvalds } 25591da177e4SLinus Torvalds 25601da177e4SLinus Torvalds /* 25611da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 25621da177e4SLinus Torvalds */ 25631da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 25641da177e4SLinus Torvalds { 25651da177e4SLinus Torvalds struct dentry *p; 25661da177e4SLinus Torvalds 25671da177e4SLinus Torvalds if (p1 == p2) { 2568f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 25691da177e4SLinus Torvalds return NULL; 25701da177e4SLinus Torvalds } 25711da177e4SLinus Torvalds 2572a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25731da177e4SLinus Torvalds 2574e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2575e2761a11SOGAWA Hirofumi if (p) { 2576f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2577f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 25781da177e4SLinus Torvalds return p; 25791da177e4SLinus Torvalds } 25801da177e4SLinus Torvalds 2581e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2582e2761a11SOGAWA Hirofumi if (p) { 2583f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2584f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 25851da177e4SLinus Torvalds return p; 25861da177e4SLinus Torvalds } 25871da177e4SLinus Torvalds 2588f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2589d1b72cc6SMiklos Szeredi mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); 25901da177e4SLinus Torvalds return NULL; 25911da177e4SLinus Torvalds } 25924d359507SAl Viro EXPORT_SYMBOL(lock_rename); 25931da177e4SLinus Torvalds 25941da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 25951da177e4SLinus Torvalds { 25961b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 25971da177e4SLinus Torvalds if (p1 != p2) { 25981b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2599a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 26001da177e4SLinus Torvalds } 26011da177e4SLinus Torvalds } 26024d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 26031da177e4SLinus Torvalds 26044acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2605312b63fbSAl Viro bool want_excl) 26061da177e4SLinus Torvalds { 2607a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 26081da177e4SLinus Torvalds if (error) 26091da177e4SLinus Torvalds return error; 26101da177e4SLinus Torvalds 2611acfa4380SAl Viro if (!dir->i_op->create) 26121da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 26131da177e4SLinus Torvalds mode &= S_IALLUGO; 26141da177e4SLinus Torvalds mode |= S_IFREG; 26151da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 26161da177e4SLinus Torvalds if (error) 26171da177e4SLinus Torvalds return error; 2618312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2619a74574aaSStephen Smalley if (!error) 2620f38aa942SAmy Griffis fsnotify_create(dir, dentry); 26211da177e4SLinus Torvalds return error; 26221da177e4SLinus Torvalds } 26234d359507SAl Viro EXPORT_SYMBOL(vfs_create); 26241da177e4SLinus Torvalds 262573d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 26261da177e4SLinus Torvalds { 26273fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 26281da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 26291da177e4SLinus Torvalds int error; 26301da177e4SLinus Torvalds 2631bcda7652SAl Viro /* O_PATH? */ 2632bcda7652SAl Viro if (!acc_mode) 2633bcda7652SAl Viro return 0; 2634bcda7652SAl Viro 26351da177e4SLinus Torvalds if (!inode) 26361da177e4SLinus Torvalds return -ENOENT; 26371da177e4SLinus Torvalds 2638c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2639c8fe8f30SChristoph Hellwig case S_IFLNK: 26401da177e4SLinus Torvalds return -ELOOP; 2641c8fe8f30SChristoph Hellwig case S_IFDIR: 2642c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 26431da177e4SLinus Torvalds return -EISDIR; 2644c8fe8f30SChristoph Hellwig break; 2645c8fe8f30SChristoph Hellwig case S_IFBLK: 2646c8fe8f30SChristoph Hellwig case S_IFCHR: 26473fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 26481da177e4SLinus Torvalds return -EACCES; 2649c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2650c8fe8f30SChristoph Hellwig case S_IFIFO: 2651c8fe8f30SChristoph Hellwig case S_IFSOCK: 26521da177e4SLinus Torvalds flag &= ~O_TRUNC; 2653c8fe8f30SChristoph Hellwig break; 26544a3fd211SDave Hansen } 2655b41572e9SDave Hansen 26563fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2657b41572e9SDave Hansen if (error) 2658b41572e9SDave Hansen return error; 26596146f0d5SMimi Zohar 26601da177e4SLinus Torvalds /* 26611da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 26621da177e4SLinus Torvalds */ 26631da177e4SLinus Torvalds if (IS_APPEND(inode)) { 26648737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 26657715b521SAl Viro return -EPERM; 26661da177e4SLinus Torvalds if (flag & O_TRUNC) 26677715b521SAl Viro return -EPERM; 26681da177e4SLinus Torvalds } 26691da177e4SLinus Torvalds 26701da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 26712e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 26727715b521SAl Viro return -EPERM; 26731da177e4SLinus Torvalds 2674f3c7691eSJ. Bruce Fields return 0; 26757715b521SAl Viro } 26767715b521SAl Viro 2677e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 26787715b521SAl Viro { 2679e1181ee6SJeff Layton struct path *path = &filp->f_path; 26807715b521SAl Viro struct inode *inode = path->dentry->d_inode; 26817715b521SAl Viro int error = get_write_access(inode); 26821da177e4SLinus Torvalds if (error) 26837715b521SAl Viro return error; 26841da177e4SLinus Torvalds /* 26851da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 26861da177e4SLinus Torvalds */ 2687d7a06983SJeff Layton error = locks_verify_locked(filp); 2688be6d3e56SKentaro Takeda if (!error) 2689ea0d3ab2STetsuo Handa error = security_path_truncate(path); 26901da177e4SLinus Torvalds if (!error) { 26917715b521SAl Viro error = do_truncate(path->dentry, 0, 2692d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2693e1181ee6SJeff Layton filp); 26941da177e4SLinus Torvalds } 26951da177e4SLinus Torvalds put_write_access(inode); 2696acd0c935SMimi Zohar return error; 26971da177e4SLinus Torvalds } 26981da177e4SLinus Torvalds 2699d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2700d57999e1SDave Hansen { 27018a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 27028a5e929dSAl Viro flag--; 2703d57999e1SDave Hansen return flag; 2704d57999e1SDave Hansen } 2705d57999e1SDave Hansen 2706d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2707d18e9008SMiklos Szeredi { 2708d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2709d18e9008SMiklos Szeredi if (error) 2710d18e9008SMiklos Szeredi return error; 2711d18e9008SMiklos Szeredi 2712d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2713d18e9008SMiklos Szeredi if (error) 2714d18e9008SMiklos Szeredi return error; 2715d18e9008SMiklos Szeredi 2716d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2717d18e9008SMiklos Szeredi } 2718d18e9008SMiklos Szeredi 27191acf0af9SDavid Howells /* 27201acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 27211acf0af9SDavid Howells * dentry. 27221acf0af9SDavid Howells * 27231acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 27241acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 27251acf0af9SDavid Howells * 27261acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 27271acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 27281acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 27291acf0af9SDavid Howells * 27301acf0af9SDavid Howells * Returns an error code otherwise. 27311acf0af9SDavid Howells */ 27322675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 273330d90494SAl Viro struct path *path, struct file *file, 2734015c3bbcSMiklos Szeredi const struct open_flags *op, 273564894cf8SAl Viro bool got_write, bool need_lookup, 273647237687SAl Viro int *opened) 2737d18e9008SMiklos Szeredi { 2738d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2739d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2740d18e9008SMiklos Szeredi umode_t mode; 2741d18e9008SMiklos Szeredi int error; 2742d18e9008SMiklos Szeredi int acc_mode; 2743d18e9008SMiklos Szeredi int create_error = 0; 2744d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2745116cc022SMiklos Szeredi bool excl; 2746d18e9008SMiklos Szeredi 2747d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2748d18e9008SMiklos Szeredi 2749d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2750d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 27512675a4ebSAl Viro error = -ENOENT; 2752d18e9008SMiklos Szeredi goto out; 2753d18e9008SMiklos Szeredi } 2754d18e9008SMiklos Szeredi 275562b259d8SMiklos Szeredi mode = op->mode; 2756d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2757d18e9008SMiklos Szeredi mode &= ~current_umask(); 2758d18e9008SMiklos Szeredi 2759116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2760116cc022SMiklos Szeredi if (excl) 2761d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2762d18e9008SMiklos Szeredi 2763d18e9008SMiklos Szeredi /* 2764d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2765d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2766d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2767d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2768d18e9008SMiklos Szeredi * 2769d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2770d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2771d18e9008SMiklos Szeredi */ 277264894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 277364894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 277464894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2775d18e9008SMiklos Szeredi /* 2776d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2777d18e9008SMiklos Szeredi * back to lookup + open 2778d18e9008SMiklos Szeredi */ 2779d18e9008SMiklos Szeredi goto no_open; 2780d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2781d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 278264894cf8SAl Viro create_error = -EROFS; 2783d18e9008SMiklos Szeredi goto no_open; 2784d18e9008SMiklos Szeredi } else { 2785d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 278664894cf8SAl Viro create_error = -EROFS; 2787d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2788d18e9008SMiklos Szeredi } 2789d18e9008SMiklos Szeredi } 2790d18e9008SMiklos Szeredi 2791d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 279238227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2793d18e9008SMiklos Szeredi if (error) { 2794d18e9008SMiklos Szeredi create_error = error; 2795d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2796d18e9008SMiklos Szeredi goto no_open; 2797d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2798d18e9008SMiklos Szeredi } 2799d18e9008SMiklos Szeredi } 2800d18e9008SMiklos Szeredi 2801d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2802d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2803d18e9008SMiklos Szeredi 280430d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 280530d90494SAl Viro file->f_path.mnt = nd->path.mnt; 280630d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 280747237687SAl Viro opened); 2808d9585277SAl Viro if (error < 0) { 2809d9585277SAl Viro if (create_error && error == -ENOENT) 2810d9585277SAl Viro error = create_error; 2811d18e9008SMiklos Szeredi goto out; 2812d18e9008SMiklos Szeredi } 2813d18e9008SMiklos Szeredi 2814d9585277SAl Viro if (error) { /* returned 1, that is */ 281530d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 28162675a4ebSAl Viro error = -EIO; 2817d18e9008SMiklos Szeredi goto out; 2818d18e9008SMiklos Szeredi } 281930d90494SAl Viro if (file->f_path.dentry) { 2820d18e9008SMiklos Szeredi dput(dentry); 282130d90494SAl Viro dentry = file->f_path.dentry; 2822d18e9008SMiklos Szeredi } 282303da633aSAl Viro if (*opened & FILE_CREATED) 282403da633aSAl Viro fsnotify_create(dir, dentry); 282503da633aSAl Viro if (!dentry->d_inode) { 282603da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 282703da633aSAl Viro if (create_error) { 282862b2ce96SSage Weil error = create_error; 282962b2ce96SSage Weil goto out; 283062b2ce96SSage Weil } 283103da633aSAl Viro } else { 283203da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 283303da633aSAl Viro error = -EEXIST; 283403da633aSAl Viro goto out; 283503da633aSAl Viro } 283603da633aSAl Viro } 2837d18e9008SMiklos Szeredi goto looked_up; 2838d18e9008SMiklos Szeredi } 2839d18e9008SMiklos Szeredi 2840d18e9008SMiklos Szeredi /* 2841d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2842d18e9008SMiklos Szeredi * here. 2843d18e9008SMiklos Szeredi */ 284403da633aSAl Viro acc_mode = op->acc_mode; 284503da633aSAl Viro if (*opened & FILE_CREATED) { 284603da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 284703da633aSAl Viro fsnotify_create(dir, dentry); 284803da633aSAl Viro acc_mode = MAY_OPEN; 284903da633aSAl Viro } 28502675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 28512675a4ebSAl Viro if (error) 28522675a4ebSAl Viro fput(file); 2853d18e9008SMiklos Szeredi 2854d18e9008SMiklos Szeredi out: 2855d18e9008SMiklos Szeredi dput(dentry); 28562675a4ebSAl Viro return error; 2857d18e9008SMiklos Szeredi 2858d18e9008SMiklos Szeredi no_open: 2859d18e9008SMiklos Szeredi if (need_lookup) { 286072bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2861d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 28622675a4ebSAl Viro return PTR_ERR(dentry); 2863d18e9008SMiklos Szeredi 2864d18e9008SMiklos Szeredi if (create_error) { 2865d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2866d18e9008SMiklos Szeredi 28672675a4ebSAl Viro error = create_error; 2868d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2869d18e9008SMiklos Szeredi if (!dentry->d_inode) 2870d18e9008SMiklos Szeredi goto out; 2871d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2872d18e9008SMiklos Szeredi goto out; 2873d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2874e36cb0b8SDavid Howells d_is_reg(dentry)) { 2875d18e9008SMiklos Szeredi goto out; 2876d18e9008SMiklos Szeredi } 2877d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2878d18e9008SMiklos Szeredi } 2879d18e9008SMiklos Szeredi } 2880d18e9008SMiklos Szeredi looked_up: 2881d18e9008SMiklos Szeredi path->dentry = dentry; 2882d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 28832675a4ebSAl Viro return 1; 2884d18e9008SMiklos Szeredi } 2885d18e9008SMiklos Szeredi 288631e6b01fSNick Piggin /* 28871acf0af9SDavid Howells * Look up and maybe create and open the last component. 2888d58ffd35SMiklos Szeredi * 2889d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2890d58ffd35SMiklos Szeredi * 28911acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 28921acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 28931acf0af9SDavid Howells * 28941acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 28951acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 28961acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 28971acf0af9SDavid Howells * specified then a negative dentry may be returned. 28981acf0af9SDavid Howells * 28991acf0af9SDavid Howells * An error code is returned otherwise. 29001acf0af9SDavid Howells * 29011acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 29021acf0af9SDavid Howells * cleared otherwise prior to returning. 2903d58ffd35SMiklos Szeredi */ 29042675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 290530d90494SAl Viro struct file *file, 2906d58ffd35SMiklos Szeredi const struct open_flags *op, 290764894cf8SAl Viro bool got_write, int *opened) 2908d58ffd35SMiklos Szeredi { 2909d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 291054ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2911d58ffd35SMiklos Szeredi struct dentry *dentry; 2912d58ffd35SMiklos Szeredi int error; 291354ef4872SMiklos Szeredi bool need_lookup; 2914d58ffd35SMiklos Szeredi 291547237687SAl Viro *opened &= ~FILE_CREATED; 2916201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2917d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 29182675a4ebSAl Viro return PTR_ERR(dentry); 2919d58ffd35SMiklos Szeredi 2920d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2921d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2922d18e9008SMiklos Szeredi goto out_no_open; 2923d18e9008SMiklos Szeredi 2924d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 292564894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 292647237687SAl Viro need_lookup, opened); 2927d18e9008SMiklos Szeredi } 2928d18e9008SMiklos Szeredi 292954ef4872SMiklos Szeredi if (need_lookup) { 293054ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 293154ef4872SMiklos Szeredi 293272bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 293354ef4872SMiklos Szeredi if (IS_ERR(dentry)) 29342675a4ebSAl Viro return PTR_ERR(dentry); 293554ef4872SMiklos Szeredi } 293654ef4872SMiklos Szeredi 2937d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2938d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2939d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2940d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2941d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2942d58ffd35SMiklos Szeredi /* 2943d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2944d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2945d58ffd35SMiklos Szeredi * the time when the file is created and when 2946d58ffd35SMiklos Szeredi * a permanent write count is taken through 2947015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 2948d58ffd35SMiklos Szeredi */ 294964894cf8SAl Viro if (!got_write) { 295064894cf8SAl Viro error = -EROFS; 2951d58ffd35SMiklos Szeredi goto out_dput; 295264894cf8SAl Viro } 295347237687SAl Viro *opened |= FILE_CREATED; 2954d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2955d58ffd35SMiklos Szeredi if (error) 2956d58ffd35SMiklos Szeredi goto out_dput; 2957312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 2958312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 2959d58ffd35SMiklos Szeredi if (error) 2960d58ffd35SMiklos Szeredi goto out_dput; 2961d58ffd35SMiklos Szeredi } 2962d18e9008SMiklos Szeredi out_no_open: 2963d58ffd35SMiklos Szeredi path->dentry = dentry; 2964d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 29652675a4ebSAl Viro return 1; 2966d58ffd35SMiklos Szeredi 2967d58ffd35SMiklos Szeredi out_dput: 2968d58ffd35SMiklos Szeredi dput(dentry); 29692675a4ebSAl Viro return error; 2970d58ffd35SMiklos Szeredi } 2971d58ffd35SMiklos Szeredi 2972d58ffd35SMiklos Szeredi /* 2973fe2d35ffSAl Viro * Handle the last step of open() 297431e6b01fSNick Piggin */ 2975896475d5SAl Viro static int do_last(struct nameidata *nd, 297630d90494SAl Viro struct file *file, const struct open_flags *op, 2977669abf4eSJeff Layton int *opened, struct filename *name) 2978fb1cc555SAl Viro { 2979a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2980ca344a89SAl Viro int open_flag = op->open_flag; 298177d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 298264894cf8SAl Viro bool got_write = false; 2983bcda7652SAl Viro int acc_mode = op->acc_mode; 2984a1eb3315SMiklos Szeredi struct inode *inode; 298516b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 2986896475d5SAl Viro struct path path; 298716b1c1cdSMiklos Szeredi bool retried = false; 298816c2cd71SAl Viro int error; 2989fb1cc555SAl Viro 2990c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2991c3e380b0SAl Viro nd->flags |= op->intent; 2992c3e380b0SAl Viro 2993bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 2994fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 299570291aecSAl Viro if (unlikely(error)) { 299670291aecSAl Viro terminate_walk(nd); 29972675a4ebSAl Viro return error; 299870291aecSAl Viro } 2999e83db167SMiklos Szeredi goto finish_open; 30001f36f774SAl Viro } 3001a2c36b45SAl Viro 3002ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3003fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3004fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3005fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3006896475d5SAl Viro error = lookup_fast(nd, &path, &inode); 300771574865SMiklos Szeredi if (likely(!error)) 300871574865SMiklos Szeredi goto finish_lookup; 300971574865SMiklos Szeredi 3010ce57dfc1SAl Viro if (error < 0) 30112675a4ebSAl Viro goto out; 3012a1eb3315SMiklos Szeredi 301337d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 3014b6183df7SMiklos Szeredi } else { 3015fe2d35ffSAl Viro /* create side of things */ 3016a3fbbde7SAl Viro /* 3017b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3018b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3019b6183df7SMiklos Szeredi * about to look up 3020a3fbbde7SAl Viro */ 30219f1fafeeSAl Viro error = complete_walk(nd); 3022e8bb73dfSAl Viro if (error) 30232675a4ebSAl Viro return error; 3024fe2d35ffSAl Viro 302533e2208aSJeff Layton audit_inode(name, dir, LOOKUP_PARENT); 302616c2cd71SAl Viro error = -EISDIR; 30271f36f774SAl Viro /* trailing slashes? */ 302831e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 30292675a4ebSAl Viro goto out; 3030b6183df7SMiklos Szeredi } 30311f36f774SAl Viro 303216b1c1cdSMiklos Szeredi retry_lookup: 303364894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 303464894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 303564894cf8SAl Viro if (!error) 303664894cf8SAl Viro got_write = true; 303764894cf8SAl Viro /* 303864894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 303964894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 304064894cf8SAl Viro * dropping this one anyway. 304164894cf8SAl Viro */ 304264894cf8SAl Viro } 3043a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 3044896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 3045fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 3046fb1cc555SAl Viro 30472675a4ebSAl Viro if (error <= 0) { 30482675a4ebSAl Viro if (error) 3049d58ffd35SMiklos Szeredi goto out; 30506c0d46c4SAl Viro 305147237687SAl Viro if ((*opened & FILE_CREATED) || 3052496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 305377d660a8SMiklos Szeredi will_truncate = false; 3054d18e9008SMiklos Szeredi 3055adb5c247SJeff Layton audit_inode(name, file->f_path.dentry, 0); 3056d18e9008SMiklos Szeredi goto opened; 3057d18e9008SMiklos Szeredi } 3058d18e9008SMiklos Szeredi 305947237687SAl Viro if (*opened & FILE_CREATED) { 30609b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3061ca344a89SAl Viro open_flag &= ~O_TRUNC; 306277d660a8SMiklos Szeredi will_truncate = false; 3063bcda7652SAl Viro acc_mode = MAY_OPEN; 3064896475d5SAl Viro path_to_nameidata(&path, nd); 3065e83db167SMiklos Szeredi goto finish_open_created; 3066fb1cc555SAl Viro } 3067fb1cc555SAl Viro 3068fb1cc555SAl Viro /* 30693134f37eSJeff Layton * create/update audit record if it already exists. 3070fb1cc555SAl Viro */ 3071896475d5SAl Viro if (d_is_positive(path.dentry)) 3072896475d5SAl Viro audit_inode(name, path.dentry, 0); 3073fb1cc555SAl Viro 3074d18e9008SMiklos Szeredi /* 3075d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3076d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3077d18e9008SMiklos Szeredi * necessary...) 3078d18e9008SMiklos Szeredi */ 307964894cf8SAl Viro if (got_write) { 3080d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 308164894cf8SAl Viro got_write = false; 3082d18e9008SMiklos Szeredi } 3083d18e9008SMiklos Szeredi 3084fb1cc555SAl Viro error = -EEXIST; 3085f8310c59SAl Viro if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) 3086fb1cc555SAl Viro goto exit_dput; 3087fb1cc555SAl Viro 3088756daf26SNeilBrown error = follow_managed(&path, nd); 30899875cf80SDavid Howells if (error < 0) 30908402752eSAl Viro goto out; 3091a3fbbde7SAl Viro 3092decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 3093896475d5SAl Viro inode = path.dentry->d_inode; 3094fb1cc555SAl Viro error = -ENOENT; 3095896475d5SAl Viro if (d_is_negative(path.dentry)) { 3096896475d5SAl Viro path_to_nameidata(&path, nd); 30972675a4ebSAl Viro goto out; 309854c33e7fSMiklos Szeredi } 3099766c4cbfSAl Viro finish_lookup: 3100191d7f73SAl Viro if (nd->depth) 3101191d7f73SAl Viro put_link(nd); 3102d63ff28fSAl Viro error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW); 3103d63ff28fSAl Viro if (unlikely(error)) { 3104d63ff28fSAl Viro if (error < 0) 3105d63ff28fSAl Viro goto out; 3106d63ff28fSAl Viro return error; 3107d45ea867SMiklos Szeredi } 3108fb1cc555SAl Viro 3109896475d5SAl Viro if (unlikely(d_is_symlink(path.dentry)) && !(open_flag & O_PATH)) { 3110896475d5SAl Viro path_to_nameidata(&path, nd); 3111a5cfe2d5SAl Viro error = -ELOOP; 3112a5cfe2d5SAl Viro goto out; 3113a5cfe2d5SAl Viro } 3114a5cfe2d5SAl Viro 3115896475d5SAl Viro if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { 3116896475d5SAl Viro path_to_nameidata(&path, nd); 311716b1c1cdSMiklos Szeredi } else { 311816b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 3119896475d5SAl Viro save_parent.mnt = mntget(path.mnt); 3120896475d5SAl Viro nd->path.dentry = path.dentry; 312116b1c1cdSMiklos Szeredi 312216b1c1cdSMiklos Szeredi } 3123decf3400SMiklos Szeredi nd->inode = inode; 3124a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3125bc77daa7SAl Viro finish_open: 3126a3fbbde7SAl Viro error = complete_walk(nd); 312716b1c1cdSMiklos Szeredi if (error) { 312816b1c1cdSMiklos Szeredi path_put(&save_parent); 31292675a4ebSAl Viro return error; 313016b1c1cdSMiklos Szeredi } 3131bc77daa7SAl Viro audit_inode(name, nd->path.dentry, 0); 3132fb1cc555SAl Viro error = -EISDIR; 313344b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 31342675a4ebSAl Viro goto out; 3135af2f5542SMiklos Szeredi error = -ENOTDIR; 313644b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 31372675a4ebSAl Viro goto out; 31384bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 313977d660a8SMiklos Szeredi will_truncate = false; 31406c0d46c4SAl Viro 31410f9d1a10SAl Viro if (will_truncate) { 31420f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 31430f9d1a10SAl Viro if (error) 31442675a4ebSAl Viro goto out; 314564894cf8SAl Viro got_write = true; 31460f9d1a10SAl Viro } 3147e83db167SMiklos Szeredi finish_open_created: 3148bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3149ca344a89SAl Viro if (error) 31502675a4ebSAl Viro goto out; 31514aa7c634SMiklos Szeredi 31524aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 31534aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 31544aa7c634SMiklos Szeredi if (!error) { 31554aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 31564aa7c634SMiklos Szeredi } else { 315730d90494SAl Viro if (error == -EOPENSTALE) 3158f60dc3dbSMiklos Szeredi goto stale_open; 3159015c3bbcSMiklos Szeredi goto out; 3160f60dc3dbSMiklos Szeredi } 3161a8277b9bSMiklos Szeredi opened: 31622675a4ebSAl Viro error = open_check_o_direct(file); 3163015c3bbcSMiklos Szeredi if (error) 3164015c3bbcSMiklos Szeredi goto exit_fput; 31653034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3166aa4caadbSMiklos Szeredi if (error) 3167aa4caadbSMiklos Szeredi goto exit_fput; 3168aa4caadbSMiklos Szeredi 31690f9d1a10SAl Viro if (will_truncate) { 31702675a4ebSAl Viro error = handle_truncate(file); 3171aa4caadbSMiklos Szeredi if (error) 3172aa4caadbSMiklos Szeredi goto exit_fput; 31730f9d1a10SAl Viro } 3174ca344a89SAl Viro out: 317564894cf8SAl Viro if (got_write) 31760f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 317716b1c1cdSMiklos Szeredi path_put(&save_parent); 3178e276ae67SMiklos Szeredi terminate_walk(nd); 31792675a4ebSAl Viro return error; 3180fb1cc555SAl Viro 3181fb1cc555SAl Viro exit_dput: 3182896475d5SAl Viro path_put_conditional(&path, nd); 3183ca344a89SAl Viro goto out; 3184015c3bbcSMiklos Szeredi exit_fput: 31852675a4ebSAl Viro fput(file); 31862675a4ebSAl Viro goto out; 3187015c3bbcSMiklos Szeredi 3188f60dc3dbSMiklos Szeredi stale_open: 3189f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3190f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3191f60dc3dbSMiklos Szeredi goto out; 3192f60dc3dbSMiklos Szeredi 3193f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3194f60dc3dbSMiklos Szeredi path_put(&nd->path); 3195f60dc3dbSMiklos Szeredi nd->path = save_parent; 3196f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3197f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3198f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 319964894cf8SAl Viro if (got_write) { 3200f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 320164894cf8SAl Viro got_write = false; 3202f60dc3dbSMiklos Szeredi } 3203f60dc3dbSMiklos Szeredi retried = true; 3204f60dc3dbSMiklos Szeredi goto retry_lookup; 3205fb1cc555SAl Viro } 3206fb1cc555SAl Viro 320760545d0dSAl Viro static int do_tmpfile(int dfd, struct filename *pathname, 320860545d0dSAl Viro struct nameidata *nd, int flags, 320960545d0dSAl Viro const struct open_flags *op, 321060545d0dSAl Viro struct file *file, int *opened) 321160545d0dSAl Viro { 321260545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 321360545d0dSAl Viro struct dentry *dentry, *child; 321460545d0dSAl Viro struct inode *dir; 32155eb6b495SAl Viro int error = path_lookupat(dfd, pathname, 321660545d0dSAl Viro flags | LOOKUP_DIRECTORY, nd); 321760545d0dSAl Viro if (unlikely(error)) 321860545d0dSAl Viro return error; 321960545d0dSAl Viro error = mnt_want_write(nd->path.mnt); 322060545d0dSAl Viro if (unlikely(error)) 322160545d0dSAl Viro goto out; 322260545d0dSAl Viro /* we want directory to be writable */ 322360545d0dSAl Viro error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); 322460545d0dSAl Viro if (error) 322560545d0dSAl Viro goto out2; 322660545d0dSAl Viro dentry = nd->path.dentry; 322760545d0dSAl Viro dir = dentry->d_inode; 322860545d0dSAl Viro if (!dir->i_op->tmpfile) { 322960545d0dSAl Viro error = -EOPNOTSUPP; 323060545d0dSAl Viro goto out2; 323160545d0dSAl Viro } 323260545d0dSAl Viro child = d_alloc(dentry, &name); 323360545d0dSAl Viro if (unlikely(!child)) { 323460545d0dSAl Viro error = -ENOMEM; 323560545d0dSAl Viro goto out2; 323660545d0dSAl Viro } 323760545d0dSAl Viro nd->flags &= ~LOOKUP_DIRECTORY; 323860545d0dSAl Viro nd->flags |= op->intent; 323960545d0dSAl Viro dput(nd->path.dentry); 324060545d0dSAl Viro nd->path.dentry = child; 324160545d0dSAl Viro error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); 324260545d0dSAl Viro if (error) 324360545d0dSAl Viro goto out2; 324460545d0dSAl Viro audit_inode(pathname, nd->path.dentry, 0); 324569a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 324669a91c23SEric Rannaud error = may_open(&nd->path, MAY_OPEN, op->open_flag); 324760545d0dSAl Viro if (error) 324860545d0dSAl Viro goto out2; 324960545d0dSAl Viro file->f_path.mnt = nd->path.mnt; 325060545d0dSAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 325160545d0dSAl Viro if (error) 325260545d0dSAl Viro goto out2; 325360545d0dSAl Viro error = open_check_o_direct(file); 3254f4e0c30cSAl Viro if (error) { 325560545d0dSAl Viro fput(file); 3256f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3257f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3258f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3259f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3260f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3261f4e0c30cSAl Viro } 326260545d0dSAl Viro out2: 326360545d0dSAl Viro mnt_drop_write(nd->path.mnt); 326460545d0dSAl Viro out: 326560545d0dSAl Viro path_put(&nd->path); 326660545d0dSAl Viro return error; 326760545d0dSAl Viro } 326860545d0dSAl Viro 3269669abf4eSJeff Layton static struct file *path_openat(int dfd, struct filename *pathname, 327073d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 32711da177e4SLinus Torvalds { 327230d90494SAl Viro struct file *file; 327347237687SAl Viro int opened = 0; 327413aab428SAl Viro int error; 327531e6b01fSNick Piggin 327630d90494SAl Viro file = get_empty_filp(); 32771afc99beSAl Viro if (IS_ERR(file)) 32781afc99beSAl Viro return file; 327931e6b01fSNick Piggin 328030d90494SAl Viro file->f_flags = op->open_flag; 328131e6b01fSNick Piggin 3282bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 328360545d0dSAl Viro error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); 3284f15133dfSAl Viro goto out2; 328560545d0dSAl Viro } 328660545d0dSAl Viro 32876e8a1f87SAl Viro error = path_init(dfd, pathname, flags, nd); 328831e6b01fSNick Piggin if (unlikely(error)) 32892675a4ebSAl Viro goto out; 32901da177e4SLinus Torvalds 3291191d7f73SAl Viro while ((error = do_last(nd, file, op, &opened, pathname)) > 0) { 329273d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 32931d8e03d3SAl Viro error = trailing_symlink(nd); 3294c3e380b0SAl Viro if (unlikely(error)) 32952675a4ebSAl Viro break; 3296806b681cSAl Viro } 329710fa8e62SAl Viro out: 3298893b7775SAl Viro path_cleanup(nd); 3299f15133dfSAl Viro out2: 33002675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 33012675a4ebSAl Viro BUG_ON(!error); 330230d90494SAl Viro put_filp(file); 3303015c3bbcSMiklos Szeredi } 33042675a4ebSAl Viro if (unlikely(error)) { 33052675a4ebSAl Viro if (error == -EOPENSTALE) { 33062675a4ebSAl Viro if (flags & LOOKUP_RCU) 33072675a4ebSAl Viro error = -ECHILD; 33082675a4ebSAl Viro else 33092675a4ebSAl Viro error = -ESTALE; 33102675a4ebSAl Viro } 33112675a4ebSAl Viro file = ERR_PTR(error); 33122675a4ebSAl Viro } 33132675a4ebSAl Viro return file; 3314de459215SKirill Korotaev } 33151da177e4SLinus Torvalds 3316669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3317f9652e10SAl Viro const struct open_flags *op) 331813aab428SAl Viro { 3319756daf26SNeilBrown struct nameidata nd, *saved_nd = set_nameidata(&nd); 3320f9652e10SAl Viro int flags = op->lookup_flags; 332113aab428SAl Viro struct file *filp; 332213aab428SAl Viro 332373d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 332413aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 332573d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 332613aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 332773d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 3328756daf26SNeilBrown restore_nameidata(saved_nd); 332913aab428SAl Viro return filp; 333013aab428SAl Viro } 333113aab428SAl Viro 333273d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3333f9652e10SAl Viro const char *name, const struct open_flags *op) 333473d049a4SAl Viro { 3335756daf26SNeilBrown struct nameidata nd, *saved_nd; 333673d049a4SAl Viro struct file *file; 333751689104SPaul Moore struct filename *filename; 3338f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 333973d049a4SAl Viro 334073d049a4SAl Viro nd.root.mnt = mnt; 334173d049a4SAl Viro nd.root.dentry = dentry; 334273d049a4SAl Viro 3343b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 334473d049a4SAl Viro return ERR_PTR(-ELOOP); 334573d049a4SAl Viro 334651689104SPaul Moore filename = getname_kernel(name); 334751689104SPaul Moore if (unlikely(IS_ERR(filename))) 334851689104SPaul Moore return ERR_CAST(filename); 334951689104SPaul Moore 3350756daf26SNeilBrown saved_nd = set_nameidata(&nd); 335151689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_RCU); 335273d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 335351689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags); 335473d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 335551689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_REVAL); 3356756daf26SNeilBrown restore_nameidata(saved_nd); 335751689104SPaul Moore putname(filename); 335873d049a4SAl Viro return file; 335973d049a4SAl Viro } 336073d049a4SAl Viro 3361fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 33621ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 33631da177e4SLinus Torvalds { 3364c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3365ed75e95dSAl Viro struct nameidata nd; 3366c30dabfeSJan Kara int err2; 33671ac12b4bSJeff Layton int error; 33681ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 33691ac12b4bSJeff Layton 33701ac12b4bSJeff Layton /* 33711ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 33721ac12b4bSJeff Layton * other flags passed in are ignored! 33731ac12b4bSJeff Layton */ 33741ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 33751ac12b4bSJeff Layton 33768bcb77faSAl Viro error = filename_parentat(dfd, name, lookup_flags, &nd); 3377ed75e95dSAl Viro if (error) 3378ed75e95dSAl Viro return ERR_PTR(error); 33791da177e4SLinus Torvalds 3380c663e5d8SChristoph Hellwig /* 3381c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3382c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3383c663e5d8SChristoph Hellwig */ 3384ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 3385ed75e95dSAl Viro goto out; 3386ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 3387ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 3388c663e5d8SChristoph Hellwig 3389c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3390c30dabfeSJan Kara err2 = mnt_want_write(nd.path.mnt); 3391c663e5d8SChristoph Hellwig /* 3392c663e5d8SChristoph Hellwig * Do the final lookup. 3393c663e5d8SChristoph Hellwig */ 3394ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 33956a9f40d6SAl Viro dentry = __lookup_hash(&nd.last, nd.path.dentry, nd.flags); 33961da177e4SLinus Torvalds if (IS_ERR(dentry)) 3397a8104a9fSAl Viro goto unlock; 3398c663e5d8SChristoph Hellwig 3399a8104a9fSAl Viro error = -EEXIST; 3400b18825a7SDavid Howells if (d_is_positive(dentry)) 3401a8104a9fSAl Viro goto fail; 3402b18825a7SDavid Howells 3403c663e5d8SChristoph Hellwig /* 3404c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3405c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3406c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3407c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3408c663e5d8SChristoph Hellwig */ 3409ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 3410a8104a9fSAl Viro error = -ENOENT; 3411ed75e95dSAl Viro goto fail; 3412e9baf6e5SAl Viro } 3413c30dabfeSJan Kara if (unlikely(err2)) { 3414c30dabfeSJan Kara error = err2; 3415a8104a9fSAl Viro goto fail; 3416c30dabfeSJan Kara } 3417ed75e95dSAl Viro *path = nd.path; 3418e9baf6e5SAl Viro return dentry; 34191da177e4SLinus Torvalds fail: 3420a8104a9fSAl Viro dput(dentry); 3421a8104a9fSAl Viro dentry = ERR_PTR(error); 3422a8104a9fSAl Viro unlock: 3423dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3424c30dabfeSJan Kara if (!err2) 3425c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 3426ed75e95dSAl Viro out: 3427dae6ad8fSAl Viro path_put(&nd.path); 3428ed75e95dSAl Viro return dentry; 3429dae6ad8fSAl Viro } 3430fa14a0b8SAl Viro 3431fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3432fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3433fa14a0b8SAl Viro { 343451689104SPaul Moore struct filename *filename = getname_kernel(pathname); 343551689104SPaul Moore struct dentry *res; 343651689104SPaul Moore 343751689104SPaul Moore if (IS_ERR(filename)) 343851689104SPaul Moore return ERR_CAST(filename); 343951689104SPaul Moore res = filename_create(dfd, filename, path, lookup_flags); 344051689104SPaul Moore putname(filename); 344151689104SPaul Moore return res; 3442fa14a0b8SAl Viro } 3443dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3444dae6ad8fSAl Viro 3445921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3446921a1650SAl Viro { 3447921a1650SAl Viro dput(dentry); 3448921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3449a8104a9fSAl Viro mnt_drop_write(path->mnt); 3450921a1650SAl Viro path_put(path); 3451921a1650SAl Viro } 3452921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3453921a1650SAl Viro 34541ac12b4bSJeff Layton struct dentry *user_path_create(int dfd, const char __user *pathname, 34551ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3456dae6ad8fSAl Viro { 345791a27b2aSJeff Layton struct filename *tmp = getname(pathname); 3458dae6ad8fSAl Viro struct dentry *res; 3459dae6ad8fSAl Viro if (IS_ERR(tmp)) 3460dae6ad8fSAl Viro return ERR_CAST(tmp); 3461fa14a0b8SAl Viro res = filename_create(dfd, tmp, path, lookup_flags); 3462dae6ad8fSAl Viro putname(tmp); 3463dae6ad8fSAl Viro return res; 3464dae6ad8fSAl Viro } 3465dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3466dae6ad8fSAl Viro 34671a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 34681da177e4SLinus Torvalds { 3469a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 34701da177e4SLinus Torvalds 34711da177e4SLinus Torvalds if (error) 34721da177e4SLinus Torvalds return error; 34731da177e4SLinus Torvalds 3474975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 34751da177e4SLinus Torvalds return -EPERM; 34761da177e4SLinus Torvalds 3477acfa4380SAl Viro if (!dir->i_op->mknod) 34781da177e4SLinus Torvalds return -EPERM; 34791da177e4SLinus Torvalds 348008ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 348108ce5f16SSerge E. Hallyn if (error) 348208ce5f16SSerge E. Hallyn return error; 348308ce5f16SSerge E. Hallyn 34841da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 34851da177e4SLinus Torvalds if (error) 34861da177e4SLinus Torvalds return error; 34871da177e4SLinus Torvalds 34881da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3489a74574aaSStephen Smalley if (!error) 3490f38aa942SAmy Griffis fsnotify_create(dir, dentry); 34911da177e4SLinus Torvalds return error; 34921da177e4SLinus Torvalds } 34934d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 34941da177e4SLinus Torvalds 3495f69aac00SAl Viro static int may_mknod(umode_t mode) 3496463c3197SDave Hansen { 3497463c3197SDave Hansen switch (mode & S_IFMT) { 3498463c3197SDave Hansen case S_IFREG: 3499463c3197SDave Hansen case S_IFCHR: 3500463c3197SDave Hansen case S_IFBLK: 3501463c3197SDave Hansen case S_IFIFO: 3502463c3197SDave Hansen case S_IFSOCK: 3503463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3504463c3197SDave Hansen return 0; 3505463c3197SDave Hansen case S_IFDIR: 3506463c3197SDave Hansen return -EPERM; 3507463c3197SDave Hansen default: 3508463c3197SDave Hansen return -EINVAL; 3509463c3197SDave Hansen } 3510463c3197SDave Hansen } 3511463c3197SDave Hansen 35128208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 35132e4d0924SHeiko Carstens unsigned, dev) 35141da177e4SLinus Torvalds { 35151da177e4SLinus Torvalds struct dentry *dentry; 3516dae6ad8fSAl Viro struct path path; 3517dae6ad8fSAl Viro int error; 3518972567f1SJeff Layton unsigned int lookup_flags = 0; 35191da177e4SLinus Torvalds 35208e4bfca1SAl Viro error = may_mknod(mode); 35218e4bfca1SAl Viro if (error) 35228e4bfca1SAl Viro return error; 3523972567f1SJeff Layton retry: 3524972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3525dae6ad8fSAl Viro if (IS_ERR(dentry)) 3526dae6ad8fSAl Viro return PTR_ERR(dentry); 35272ad94ae6SAl Viro 3528dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3529ce3b0f8dSAl Viro mode &= ~current_umask(); 3530dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3531be6d3e56SKentaro Takeda if (error) 3532a8104a9fSAl Viro goto out; 35331da177e4SLinus Torvalds switch (mode & S_IFMT) { 35341da177e4SLinus Torvalds case 0: case S_IFREG: 3535312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 35361da177e4SLinus Torvalds break; 35371da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3538dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 35391da177e4SLinus Torvalds new_decode_dev(dev)); 35401da177e4SLinus Torvalds break; 35411da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3542dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 35431da177e4SLinus Torvalds break; 35441da177e4SLinus Torvalds } 3545a8104a9fSAl Viro out: 3546921a1650SAl Viro done_path_create(&path, dentry); 3547972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3548972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3549972567f1SJeff Layton goto retry; 3550972567f1SJeff Layton } 35511da177e4SLinus Torvalds return error; 35521da177e4SLinus Torvalds } 35531da177e4SLinus Torvalds 35548208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 35555590ff0dSUlrich Drepper { 35565590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 35575590ff0dSUlrich Drepper } 35585590ff0dSUlrich Drepper 355918bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 35601da177e4SLinus Torvalds { 3561a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35628de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 35631da177e4SLinus Torvalds 35641da177e4SLinus Torvalds if (error) 35651da177e4SLinus Torvalds return error; 35661da177e4SLinus Torvalds 3567acfa4380SAl Viro if (!dir->i_op->mkdir) 35681da177e4SLinus Torvalds return -EPERM; 35691da177e4SLinus Torvalds 35701da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 35711da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 35721da177e4SLinus Torvalds if (error) 35731da177e4SLinus Torvalds return error; 35741da177e4SLinus Torvalds 35758de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 35768de52778SAl Viro return -EMLINK; 35778de52778SAl Viro 35781da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3579a74574aaSStephen Smalley if (!error) 3580f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 35811da177e4SLinus Torvalds return error; 35821da177e4SLinus Torvalds } 35834d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 35841da177e4SLinus Torvalds 3585a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 35861da177e4SLinus Torvalds { 35876902d925SDave Hansen struct dentry *dentry; 3588dae6ad8fSAl Viro struct path path; 3589dae6ad8fSAl Viro int error; 3590b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 35911da177e4SLinus Torvalds 3592b76d8b82SJeff Layton retry: 3593b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 35946902d925SDave Hansen if (IS_ERR(dentry)) 3595dae6ad8fSAl Viro return PTR_ERR(dentry); 35966902d925SDave Hansen 3597dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3598ce3b0f8dSAl Viro mode &= ~current_umask(); 3599dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3600a8104a9fSAl Viro if (!error) 3601dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3602921a1650SAl Viro done_path_create(&path, dentry); 3603b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3604b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3605b76d8b82SJeff Layton goto retry; 3606b76d8b82SJeff Layton } 36071da177e4SLinus Torvalds return error; 36081da177e4SLinus Torvalds } 36091da177e4SLinus Torvalds 3610a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 36115590ff0dSUlrich Drepper { 36125590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 36135590ff0dSUlrich Drepper } 36145590ff0dSUlrich Drepper 36151da177e4SLinus Torvalds /* 3616a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3617c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3618a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3619a71905f0SSage Weil * then we drop the dentry now. 36201da177e4SLinus Torvalds * 36211da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 36221da177e4SLinus Torvalds * do a 36231da177e4SLinus Torvalds * 36241da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 36251da177e4SLinus Torvalds * return -EBUSY; 36261da177e4SLinus Torvalds * 36271da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 36281da177e4SLinus Torvalds * that is still in use by something else.. 36291da177e4SLinus Torvalds */ 36301da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 36311da177e4SLinus Torvalds { 36321da177e4SLinus Torvalds shrink_dcache_parent(dentry); 36331da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 363498474236SWaiman Long if (dentry->d_lockref.count == 1) 36351da177e4SLinus Torvalds __d_drop(dentry); 36361da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 36371da177e4SLinus Torvalds } 36384d359507SAl Viro EXPORT_SYMBOL(dentry_unhash); 36391da177e4SLinus Torvalds 36401da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 36411da177e4SLinus Torvalds { 36421da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 36431da177e4SLinus Torvalds 36441da177e4SLinus Torvalds if (error) 36451da177e4SLinus Torvalds return error; 36461da177e4SLinus Torvalds 3647acfa4380SAl Viro if (!dir->i_op->rmdir) 36481da177e4SLinus Torvalds return -EPERM; 36491da177e4SLinus Torvalds 36501d2ef590SAl Viro dget(dentry); 36511b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3652912dbc15SSage Weil 36531da177e4SLinus Torvalds error = -EBUSY; 36547af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3655912dbc15SSage Weil goto out; 3656912dbc15SSage Weil 36571da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3658912dbc15SSage Weil if (error) 3659912dbc15SSage Weil goto out; 3660912dbc15SSage Weil 36613cebde24SSage Weil shrink_dcache_parent(dentry); 36621da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3663912dbc15SSage Weil if (error) 3664912dbc15SSage Weil goto out; 3665912dbc15SSage Weil 36661da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3667d83c49f3SAl Viro dont_mount(dentry); 36688ed936b5SEric W. Biederman detach_mounts(dentry); 36691da177e4SLinus Torvalds 3670912dbc15SSage Weil out: 3671912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 36721d2ef590SAl Viro dput(dentry); 3673912dbc15SSage Weil if (!error) 3674912dbc15SSage Weil d_delete(dentry); 36751da177e4SLinus Torvalds return error; 36761da177e4SLinus Torvalds } 36774d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 36781da177e4SLinus Torvalds 36795590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 36801da177e4SLinus Torvalds { 36811da177e4SLinus Torvalds int error = 0; 368291a27b2aSJeff Layton struct filename *name; 36831da177e4SLinus Torvalds struct dentry *dentry; 3684f5beed75SAl Viro struct path path; 3685f5beed75SAl Viro struct qstr last; 3686f5beed75SAl Viro int type; 3687c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3688c6ee9206SJeff Layton retry: 3689f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3690f5beed75SAl Viro &path, &last, &type, lookup_flags); 369191a27b2aSJeff Layton if (IS_ERR(name)) 369291a27b2aSJeff Layton return PTR_ERR(name); 36931da177e4SLinus Torvalds 3694f5beed75SAl Viro switch (type) { 36951da177e4SLinus Torvalds case LAST_DOTDOT: 36961da177e4SLinus Torvalds error = -ENOTEMPTY; 36971da177e4SLinus Torvalds goto exit1; 36981da177e4SLinus Torvalds case LAST_DOT: 36991da177e4SLinus Torvalds error = -EINVAL; 37001da177e4SLinus Torvalds goto exit1; 37011da177e4SLinus Torvalds case LAST_ROOT: 37021da177e4SLinus Torvalds error = -EBUSY; 37031da177e4SLinus Torvalds goto exit1; 37041da177e4SLinus Torvalds } 37050612d9fbSOGAWA Hirofumi 3706f5beed75SAl Viro error = mnt_want_write(path.mnt); 3707c30dabfeSJan Kara if (error) 3708c30dabfeSJan Kara goto exit1; 37090612d9fbSOGAWA Hirofumi 3710f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3711f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 37121da177e4SLinus Torvalds error = PTR_ERR(dentry); 37136902d925SDave Hansen if (IS_ERR(dentry)) 37146902d925SDave Hansen goto exit2; 3715e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3716e6bc45d6STheodore Ts'o error = -ENOENT; 3717e6bc45d6STheodore Ts'o goto exit3; 3718e6bc45d6STheodore Ts'o } 3719f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3720be6d3e56SKentaro Takeda if (error) 3721c30dabfeSJan Kara goto exit3; 3722f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 37230622753bSDave Hansen exit3: 37241da177e4SLinus Torvalds dput(dentry); 37256902d925SDave Hansen exit2: 3726f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 3727f5beed75SAl Viro mnt_drop_write(path.mnt); 37281da177e4SLinus Torvalds exit1: 3729f5beed75SAl Viro path_put(&path); 37301da177e4SLinus Torvalds putname(name); 3731c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3732c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3733c6ee9206SJeff Layton goto retry; 3734c6ee9206SJeff Layton } 37351da177e4SLinus Torvalds return error; 37361da177e4SLinus Torvalds } 37371da177e4SLinus Torvalds 37383cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 37395590ff0dSUlrich Drepper { 37405590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 37415590ff0dSUlrich Drepper } 37425590ff0dSUlrich Drepper 3743b21996e3SJ. Bruce Fields /** 3744b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3745b21996e3SJ. Bruce Fields * @dir: parent directory 3746b21996e3SJ. Bruce Fields * @dentry: victim 3747b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3748b21996e3SJ. Bruce Fields * 3749b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3750b21996e3SJ. Bruce Fields * 3751b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3752b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3753b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3754b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3755b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3756b21996e3SJ. Bruce Fields * 3757b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3758b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3759b21996e3SJ. Bruce Fields * to be NFS exported. 3760b21996e3SJ. Bruce Fields */ 3761b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 37621da177e4SLinus Torvalds { 37639accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 37641da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 37651da177e4SLinus Torvalds 37661da177e4SLinus Torvalds if (error) 37671da177e4SLinus Torvalds return error; 37681da177e4SLinus Torvalds 3769acfa4380SAl Viro if (!dir->i_op->unlink) 37701da177e4SLinus Torvalds return -EPERM; 37711da177e4SLinus Torvalds 37729accbb97SJ. Bruce Fields mutex_lock(&target->i_mutex); 37738ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 37741da177e4SLinus Torvalds error = -EBUSY; 37751da177e4SLinus Torvalds else { 37761da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3777bec1052eSAl Viro if (!error) { 37785a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 37795a14696cSJ. Bruce Fields if (error) 3780b21996e3SJ. Bruce Fields goto out; 37811da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 37828ed936b5SEric W. Biederman if (!error) { 3783d83c49f3SAl Viro dont_mount(dentry); 37848ed936b5SEric W. Biederman detach_mounts(dentry); 37858ed936b5SEric W. Biederman } 3786bec1052eSAl Viro } 37871da177e4SLinus Torvalds } 3788b21996e3SJ. Bruce Fields out: 37899accbb97SJ. Bruce Fields mutex_unlock(&target->i_mutex); 37901da177e4SLinus Torvalds 37911da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 37921da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 37939accbb97SJ. Bruce Fields fsnotify_link_count(target); 37941da177e4SLinus Torvalds d_delete(dentry); 37951da177e4SLinus Torvalds } 37960eeca283SRobert Love 37971da177e4SLinus Torvalds return error; 37981da177e4SLinus Torvalds } 37994d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 38001da177e4SLinus Torvalds 38011da177e4SLinus Torvalds /* 38021da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 38031b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 38041da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 38051da177e4SLinus Torvalds * while waiting on the I/O. 38061da177e4SLinus Torvalds */ 38075590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 38081da177e4SLinus Torvalds { 38092ad94ae6SAl Viro int error; 381091a27b2aSJeff Layton struct filename *name; 38111da177e4SLinus Torvalds struct dentry *dentry; 3812f5beed75SAl Viro struct path path; 3813f5beed75SAl Viro struct qstr last; 3814f5beed75SAl Viro int type; 38151da177e4SLinus Torvalds struct inode *inode = NULL; 3816b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 38175d18f813SJeff Layton unsigned int lookup_flags = 0; 38185d18f813SJeff Layton retry: 3819f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3820f5beed75SAl Viro &path, &last, &type, lookup_flags); 382191a27b2aSJeff Layton if (IS_ERR(name)) 382291a27b2aSJeff Layton return PTR_ERR(name); 38232ad94ae6SAl Viro 38241da177e4SLinus Torvalds error = -EISDIR; 3825f5beed75SAl Viro if (type != LAST_NORM) 38261da177e4SLinus Torvalds goto exit1; 38270612d9fbSOGAWA Hirofumi 3828f5beed75SAl Viro error = mnt_want_write(path.mnt); 3829c30dabfeSJan Kara if (error) 3830c30dabfeSJan Kara goto exit1; 3831b21996e3SJ. Bruce Fields retry_deleg: 3832f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3833f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38341da177e4SLinus Torvalds error = PTR_ERR(dentry); 38351da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 38361da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3837f5beed75SAl Viro if (last.name[last.len]) 383850338b88STörök Edwin goto slashes; 38391da177e4SLinus Torvalds inode = dentry->d_inode; 3840b18825a7SDavid Howells if (d_is_negative(dentry)) 3841e6bc45d6STheodore Ts'o goto slashes; 38427de9c6eeSAl Viro ihold(inode); 3843f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3844be6d3e56SKentaro Takeda if (error) 3845c30dabfeSJan Kara goto exit2; 3846f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 38471da177e4SLinus Torvalds exit2: 38481da177e4SLinus Torvalds dput(dentry); 38491da177e4SLinus Torvalds } 3850f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 38511da177e4SLinus Torvalds if (inode) 38521da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3853b21996e3SJ. Bruce Fields inode = NULL; 3854b21996e3SJ. Bruce Fields if (delegated_inode) { 38555a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3856b21996e3SJ. Bruce Fields if (!error) 3857b21996e3SJ. Bruce Fields goto retry_deleg; 3858b21996e3SJ. Bruce Fields } 3859f5beed75SAl Viro mnt_drop_write(path.mnt); 38601da177e4SLinus Torvalds exit1: 3861f5beed75SAl Viro path_put(&path); 38621da177e4SLinus Torvalds putname(name); 38635d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 38645d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 38655d18f813SJeff Layton inode = NULL; 38665d18f813SJeff Layton goto retry; 38675d18f813SJeff Layton } 38681da177e4SLinus Torvalds return error; 38691da177e4SLinus Torvalds 38701da177e4SLinus Torvalds slashes: 3871b18825a7SDavid Howells if (d_is_negative(dentry)) 3872b18825a7SDavid Howells error = -ENOENT; 387344b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3874b18825a7SDavid Howells error = -EISDIR; 3875b18825a7SDavid Howells else 3876b18825a7SDavid Howells error = -ENOTDIR; 38771da177e4SLinus Torvalds goto exit2; 38781da177e4SLinus Torvalds } 38791da177e4SLinus Torvalds 38802e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 38815590ff0dSUlrich Drepper { 38825590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 38835590ff0dSUlrich Drepper return -EINVAL; 38845590ff0dSUlrich Drepper 38855590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 38865590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 38875590ff0dSUlrich Drepper 38885590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 38895590ff0dSUlrich Drepper } 38905590ff0dSUlrich Drepper 38913480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 38925590ff0dSUlrich Drepper { 38935590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 38945590ff0dSUlrich Drepper } 38955590ff0dSUlrich Drepper 3896db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 38971da177e4SLinus Torvalds { 3898a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 38991da177e4SLinus Torvalds 39001da177e4SLinus Torvalds if (error) 39011da177e4SLinus Torvalds return error; 39021da177e4SLinus Torvalds 3903acfa4380SAl Viro if (!dir->i_op->symlink) 39041da177e4SLinus Torvalds return -EPERM; 39051da177e4SLinus Torvalds 39061da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 39071da177e4SLinus Torvalds if (error) 39081da177e4SLinus Torvalds return error; 39091da177e4SLinus Torvalds 39101da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3911a74574aaSStephen Smalley if (!error) 3912f38aa942SAmy Griffis fsnotify_create(dir, dentry); 39131da177e4SLinus Torvalds return error; 39141da177e4SLinus Torvalds } 39154d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 39161da177e4SLinus Torvalds 39172e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 39182e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 39191da177e4SLinus Torvalds { 39202ad94ae6SAl Viro int error; 392191a27b2aSJeff Layton struct filename *from; 39226902d925SDave Hansen struct dentry *dentry; 3923dae6ad8fSAl Viro struct path path; 3924f46d3567SJeff Layton unsigned int lookup_flags = 0; 39251da177e4SLinus Torvalds 39261da177e4SLinus Torvalds from = getname(oldname); 39271da177e4SLinus Torvalds if (IS_ERR(from)) 39281da177e4SLinus Torvalds return PTR_ERR(from); 3929f46d3567SJeff Layton retry: 3930f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 39311da177e4SLinus Torvalds error = PTR_ERR(dentry); 39326902d925SDave Hansen if (IS_ERR(dentry)) 3933dae6ad8fSAl Viro goto out_putname; 39346902d925SDave Hansen 393591a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3936a8104a9fSAl Viro if (!error) 393791a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3938921a1650SAl Viro done_path_create(&path, dentry); 3939f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 3940f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 3941f46d3567SJeff Layton goto retry; 3942f46d3567SJeff Layton } 39436902d925SDave Hansen out_putname: 39441da177e4SLinus Torvalds putname(from); 39451da177e4SLinus Torvalds return error; 39461da177e4SLinus Torvalds } 39471da177e4SLinus Torvalds 39483480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 39495590ff0dSUlrich Drepper { 39505590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 39515590ff0dSUlrich Drepper } 39525590ff0dSUlrich Drepper 3953146a8595SJ. Bruce Fields /** 3954146a8595SJ. Bruce Fields * vfs_link - create a new link 3955146a8595SJ. Bruce Fields * @old_dentry: object to be linked 3956146a8595SJ. Bruce Fields * @dir: new parent 3957146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 3958146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 3959146a8595SJ. Bruce Fields * 3960146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 3961146a8595SJ. Bruce Fields * 3962146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 3963146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 3964146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 3965146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 3966146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 3967146a8595SJ. Bruce Fields * 3968146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3969146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3970146a8595SJ. Bruce Fields * to be NFS exported. 3971146a8595SJ. Bruce Fields */ 3972146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 39731da177e4SLinus Torvalds { 39741da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 39758de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 39761da177e4SLinus Torvalds int error; 39771da177e4SLinus Torvalds 39781da177e4SLinus Torvalds if (!inode) 39791da177e4SLinus Torvalds return -ENOENT; 39801da177e4SLinus Torvalds 3981a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 39821da177e4SLinus Torvalds if (error) 39831da177e4SLinus Torvalds return error; 39841da177e4SLinus Torvalds 39851da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 39861da177e4SLinus Torvalds return -EXDEV; 39871da177e4SLinus Torvalds 39881da177e4SLinus Torvalds /* 39891da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 39901da177e4SLinus Torvalds */ 39911da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 39921da177e4SLinus Torvalds return -EPERM; 3993acfa4380SAl Viro if (!dir->i_op->link) 39941da177e4SLinus Torvalds return -EPERM; 39957e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 39961da177e4SLinus Torvalds return -EPERM; 39971da177e4SLinus Torvalds 39981da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 39991da177e4SLinus Torvalds if (error) 40001da177e4SLinus Torvalds return error; 40011da177e4SLinus Torvalds 40027e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 4003aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4004f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4005aae8a97dSAneesh Kumar K.V error = -ENOENT; 40068de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 40078de52778SAl Viro error = -EMLINK; 4008146a8595SJ. Bruce Fields else { 4009146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4010146a8595SJ. Bruce Fields if (!error) 40111da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4012146a8595SJ. Bruce Fields } 4013f4e0c30cSAl Viro 4014f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4015f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4016f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4017f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4018f4e0c30cSAl Viro } 40197e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 4020e31e14ecSStephen Smalley if (!error) 40217e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 40221da177e4SLinus Torvalds return error; 40231da177e4SLinus Torvalds } 40244d359507SAl Viro EXPORT_SYMBOL(vfs_link); 40251da177e4SLinus Torvalds 40261da177e4SLinus Torvalds /* 40271da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 40281da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 40291da177e4SLinus Torvalds * newname. --KAB 40301da177e4SLinus Torvalds * 40311da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 40321da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 40331da177e4SLinus Torvalds * and other special files. --ADM 40341da177e4SLinus Torvalds */ 40352e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 40362e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 40371da177e4SLinus Torvalds { 40381da177e4SLinus Torvalds struct dentry *new_dentry; 4039dae6ad8fSAl Viro struct path old_path, new_path; 4040146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 404111a7b371SAneesh Kumar K.V int how = 0; 40421da177e4SLinus Torvalds int error; 40431da177e4SLinus Torvalds 404411a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4045c04030e1SUlrich Drepper return -EINVAL; 404611a7b371SAneesh Kumar K.V /* 4047f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4048f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4049f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 405011a7b371SAneesh Kumar K.V */ 4051f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4052f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4053f0cc6ffbSLinus Torvalds return -ENOENT; 405411a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4055f0cc6ffbSLinus Torvalds } 4056c04030e1SUlrich Drepper 405711a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 405811a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4059442e31caSJeff Layton retry: 406011a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 40611da177e4SLinus Torvalds if (error) 40622ad94ae6SAl Viro return error; 40632ad94ae6SAl Viro 4064442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4065442e31caSJeff Layton (how & LOOKUP_REVAL)); 40661da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 40676902d925SDave Hansen if (IS_ERR(new_dentry)) 4068dae6ad8fSAl Viro goto out; 4069dae6ad8fSAl Viro 4070dae6ad8fSAl Viro error = -EXDEV; 4071dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4072dae6ad8fSAl Viro goto out_dput; 4073800179c9SKees Cook error = may_linkat(&old_path); 4074800179c9SKees Cook if (unlikely(error)) 4075800179c9SKees Cook goto out_dput; 4076dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4077be6d3e56SKentaro Takeda if (error) 4078a8104a9fSAl Viro goto out_dput; 4079146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 408075c3f29dSDave Hansen out_dput: 4081921a1650SAl Viro done_path_create(&new_path, new_dentry); 4082146a8595SJ. Bruce Fields if (delegated_inode) { 4083146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4084d22e6338SOleg Drokin if (!error) { 4085d22e6338SOleg Drokin path_put(&old_path); 4086146a8595SJ. Bruce Fields goto retry; 4087146a8595SJ. Bruce Fields } 4088d22e6338SOleg Drokin } 4089442e31caSJeff Layton if (retry_estale(error, how)) { 4090d22e6338SOleg Drokin path_put(&old_path); 4091442e31caSJeff Layton how |= LOOKUP_REVAL; 4092442e31caSJeff Layton goto retry; 4093442e31caSJeff Layton } 40941da177e4SLinus Torvalds out: 40952d8f3038SAl Viro path_put(&old_path); 40961da177e4SLinus Torvalds 40971da177e4SLinus Torvalds return error; 40981da177e4SLinus Torvalds } 40991da177e4SLinus Torvalds 41003480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 41015590ff0dSUlrich Drepper { 4102c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 41035590ff0dSUlrich Drepper } 41045590ff0dSUlrich Drepper 4105bc27027aSMiklos Szeredi /** 4106bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4107bc27027aSMiklos Szeredi * @old_dir: parent of source 4108bc27027aSMiklos Szeredi * @old_dentry: source 4109bc27027aSMiklos Szeredi * @new_dir: parent of destination 4110bc27027aSMiklos Szeredi * @new_dentry: destination 4111bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4112520c8b16SMiklos Szeredi * @flags: rename flags 4113bc27027aSMiklos Szeredi * 4114bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4115bc27027aSMiklos Szeredi * 4116bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4117bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4118bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4119bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4120bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4121bc27027aSMiklos Szeredi * so. 4122bc27027aSMiklos Szeredi * 4123bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4124bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4125bc27027aSMiklos Szeredi * to be NFS exported. 4126bc27027aSMiklos Szeredi * 41271da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 41281da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 41291da177e4SLinus Torvalds * Problems: 4130d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 41311da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 41321da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4133a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 41341da177e4SLinus Torvalds * story. 41356cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 41366cedba89SJ. Bruce Fields * and source (if it is not a directory). 41371b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 41381da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 41391da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4140a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 41411da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 41421da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 41431da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4144a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 41451da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 41461da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 41471da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4148e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 41491b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 41501da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4151c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 41521da177e4SLinus Torvalds * locking]. 41531da177e4SLinus Torvalds */ 41541da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 41558e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4156520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 41571da177e4SLinus Torvalds { 41581da177e4SLinus Torvalds int error; 4159bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 416059b0df21SEric Paris const unsigned char *old_name; 4161bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4162bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4163da1ce067SMiklos Szeredi bool new_is_dir = false; 4164da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 41651da177e4SLinus Torvalds 4166bc27027aSMiklos Szeredi if (source == target) 41671da177e4SLinus Torvalds return 0; 41681da177e4SLinus Torvalds 41691da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 41701da177e4SLinus Torvalds if (error) 41711da177e4SLinus Torvalds return error; 41721da177e4SLinus Torvalds 4173da1ce067SMiklos Szeredi if (!target) { 4174a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4175da1ce067SMiklos Szeredi } else { 4176da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4177da1ce067SMiklos Szeredi 4178da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 41791da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4180da1ce067SMiklos Szeredi else 4181da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4182da1ce067SMiklos Szeredi } 41831da177e4SLinus Torvalds if (error) 41841da177e4SLinus Torvalds return error; 41851da177e4SLinus Torvalds 41867177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 41871da177e4SLinus Torvalds return -EPERM; 41881da177e4SLinus Torvalds 4189520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4190520c8b16SMiklos Szeredi return -EINVAL; 4191520c8b16SMiklos Szeredi 4192bc27027aSMiklos Szeredi /* 4193bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4194bc27027aSMiklos Szeredi * we'll need to flip '..'. 4195bc27027aSMiklos Szeredi */ 4196da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4197da1ce067SMiklos Szeredi if (is_dir) { 4198bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4199bc27027aSMiklos Szeredi if (error) 4200bc27027aSMiklos Szeredi return error; 4201bc27027aSMiklos Szeredi } 4202da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4203da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4204da1ce067SMiklos Szeredi if (error) 4205da1ce067SMiklos Szeredi return error; 4206da1ce067SMiklos Szeredi } 4207da1ce067SMiklos Szeredi } 42080eeca283SRobert Love 42090b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 42100b3974ebSMiklos Szeredi flags); 4211bc27027aSMiklos Szeredi if (error) 4212bc27027aSMiklos Szeredi return error; 4213bc27027aSMiklos Szeredi 4214bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4215bc27027aSMiklos Szeredi dget(new_dentry); 4216da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4217bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4218bc27027aSMiklos Szeredi else if (target) 4219bc27027aSMiklos Szeredi mutex_lock(&target->i_mutex); 4220bc27027aSMiklos Szeredi 4221bc27027aSMiklos Szeredi error = -EBUSY; 42227af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4223bc27027aSMiklos Szeredi goto out; 4224bc27027aSMiklos Szeredi 4225da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4226bc27027aSMiklos Szeredi error = -EMLINK; 4227da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4228bc27027aSMiklos Szeredi goto out; 4229da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4230da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4231da1ce067SMiklos Szeredi goto out; 4232da1ce067SMiklos Szeredi } 4233da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4234bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4235da1ce067SMiklos Szeredi if (!is_dir) { 4236bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4237bc27027aSMiklos Szeredi if (error) 4238bc27027aSMiklos Szeredi goto out; 4239da1ce067SMiklos Szeredi } 4240da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4241bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4242bc27027aSMiklos Szeredi if (error) 4243bc27027aSMiklos Szeredi goto out; 4244bc27027aSMiklos Szeredi } 42457177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4246520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4247520c8b16SMiklos Szeredi new_dir, new_dentry); 4248520c8b16SMiklos Szeredi } else { 42497177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4250520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4251520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4252520c8b16SMiklos Szeredi } 4253bc27027aSMiklos Szeredi if (error) 4254bc27027aSMiklos Szeredi goto out; 4255bc27027aSMiklos Szeredi 4256da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 42571da177e4SLinus Torvalds if (is_dir) 4258bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4259bc27027aSMiklos Szeredi dont_mount(new_dentry); 42608ed936b5SEric W. Biederman detach_mounts(new_dentry); 4261bc27027aSMiklos Szeredi } 4262da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4263da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4264bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4265da1ce067SMiklos Szeredi else 4266da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4267da1ce067SMiklos Szeredi } 4268bc27027aSMiklos Szeredi out: 4269da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4270bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4271bc27027aSMiklos Szeredi else if (target) 4272bc27027aSMiklos Szeredi mutex_unlock(&target->i_mutex); 4273bc27027aSMiklos Szeredi dput(new_dentry); 4274da1ce067SMiklos Szeredi if (!error) { 4275123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4276da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4277da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4278da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4279da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4280da1ce067SMiklos Szeredi } 4281da1ce067SMiklos Szeredi } 42820eeca283SRobert Love fsnotify_oldname_free(old_name); 42830eeca283SRobert Love 42841da177e4SLinus Torvalds return error; 42851da177e4SLinus Torvalds } 42864d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 42871da177e4SLinus Torvalds 4288520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4289520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 42901da177e4SLinus Torvalds { 42911da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 42921da177e4SLinus Torvalds struct dentry *trap; 4293f5beed75SAl Viro struct path old_path, new_path; 4294f5beed75SAl Viro struct qstr old_last, new_last; 4295f5beed75SAl Viro int old_type, new_type; 42968e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 429791a27b2aSJeff Layton struct filename *from; 429891a27b2aSJeff Layton struct filename *to; 4299f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4300c6a94284SJeff Layton bool should_retry = false; 43012ad94ae6SAl Viro int error; 4302520c8b16SMiklos Szeredi 43030d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4304da1ce067SMiklos Szeredi return -EINVAL; 4305da1ce067SMiklos Szeredi 43060d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 43070d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4308520c8b16SMiklos Szeredi return -EINVAL; 4309520c8b16SMiklos Szeredi 43100d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 43110d7a8555SMiklos Szeredi return -EPERM; 43120d7a8555SMiklos Szeredi 4313f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4314f5beed75SAl Viro target_flags = 0; 4315f5beed75SAl Viro 4316c6a94284SJeff Layton retry: 4317f5beed75SAl Viro from = user_path_parent(olddfd, oldname, 4318f5beed75SAl Viro &old_path, &old_last, &old_type, lookup_flags); 431991a27b2aSJeff Layton if (IS_ERR(from)) { 432091a27b2aSJeff Layton error = PTR_ERR(from); 43211da177e4SLinus Torvalds goto exit; 432291a27b2aSJeff Layton } 43231da177e4SLinus Torvalds 4324f5beed75SAl Viro to = user_path_parent(newdfd, newname, 4325f5beed75SAl Viro &new_path, &new_last, &new_type, lookup_flags); 432691a27b2aSJeff Layton if (IS_ERR(to)) { 432791a27b2aSJeff Layton error = PTR_ERR(to); 43281da177e4SLinus Torvalds goto exit1; 432991a27b2aSJeff Layton } 43301da177e4SLinus Torvalds 43311da177e4SLinus Torvalds error = -EXDEV; 4332f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 43331da177e4SLinus Torvalds goto exit2; 43341da177e4SLinus Torvalds 43351da177e4SLinus Torvalds error = -EBUSY; 4336f5beed75SAl Viro if (old_type != LAST_NORM) 43371da177e4SLinus Torvalds goto exit2; 43381da177e4SLinus Torvalds 43390a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 43400a7c3937SMiklos Szeredi error = -EEXIST; 4341f5beed75SAl Viro if (new_type != LAST_NORM) 43421da177e4SLinus Torvalds goto exit2; 43431da177e4SLinus Torvalds 4344f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4345c30dabfeSJan Kara if (error) 4346c30dabfeSJan Kara goto exit2; 4347c30dabfeSJan Kara 43488e6d782cSJ. Bruce Fields retry_deleg: 4349f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 43501da177e4SLinus Torvalds 4351f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 43521da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 43531da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 43541da177e4SLinus Torvalds goto exit3; 43551da177e4SLinus Torvalds /* source must exist */ 43561da177e4SLinus Torvalds error = -ENOENT; 4357b18825a7SDavid Howells if (d_is_negative(old_dentry)) 43581da177e4SLinus Torvalds goto exit4; 4359f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 43601da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 43611da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 43621da177e4SLinus Torvalds goto exit4; 43630a7c3937SMiklos Szeredi error = -EEXIST; 43640a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 43650a7c3937SMiklos Szeredi goto exit5; 4366da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4367da1ce067SMiklos Szeredi error = -ENOENT; 4368da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4369da1ce067SMiklos Szeredi goto exit5; 4370da1ce067SMiklos Szeredi 4371da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4372da1ce067SMiklos Szeredi error = -ENOTDIR; 4373f5beed75SAl Viro if (new_last.name[new_last.len]) 4374da1ce067SMiklos Szeredi goto exit5; 4375da1ce067SMiklos Szeredi } 4376da1ce067SMiklos Szeredi } 43770a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 43780a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 43790a7c3937SMiklos Szeredi error = -ENOTDIR; 4380f5beed75SAl Viro if (old_last.name[old_last.len]) 43810a7c3937SMiklos Szeredi goto exit5; 4382f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 43830a7c3937SMiklos Szeredi goto exit5; 43840a7c3937SMiklos Szeredi } 43850a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 43860a7c3937SMiklos Szeredi error = -EINVAL; 43870a7c3937SMiklos Szeredi if (old_dentry == trap) 43880a7c3937SMiklos Szeredi goto exit5; 43891da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4390da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43911da177e4SLinus Torvalds error = -ENOTEMPTY; 43921da177e4SLinus Torvalds if (new_dentry == trap) 43931da177e4SLinus Torvalds goto exit5; 43941da177e4SLinus Torvalds 4395f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4396f5beed75SAl Viro &new_path, new_dentry, flags); 4397be6d3e56SKentaro Takeda if (error) 4398c30dabfeSJan Kara goto exit5; 4399f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4400f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4401520c8b16SMiklos Szeredi &delegated_inode, flags); 44021da177e4SLinus Torvalds exit5: 44031da177e4SLinus Torvalds dput(new_dentry); 44041da177e4SLinus Torvalds exit4: 44051da177e4SLinus Torvalds dput(old_dentry); 44061da177e4SLinus Torvalds exit3: 4407f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 44088e6d782cSJ. Bruce Fields if (delegated_inode) { 44098e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 44108e6d782cSJ. Bruce Fields if (!error) 44118e6d782cSJ. Bruce Fields goto retry_deleg; 44128e6d782cSJ. Bruce Fields } 4413f5beed75SAl Viro mnt_drop_write(old_path.mnt); 44141da177e4SLinus Torvalds exit2: 4415c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4416c6a94284SJeff Layton should_retry = true; 4417f5beed75SAl Viro path_put(&new_path); 44182ad94ae6SAl Viro putname(to); 44191da177e4SLinus Torvalds exit1: 4420f5beed75SAl Viro path_put(&old_path); 44211da177e4SLinus Torvalds putname(from); 4422c6a94284SJeff Layton if (should_retry) { 4423c6a94284SJeff Layton should_retry = false; 4424c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4425c6a94284SJeff Layton goto retry; 4426c6a94284SJeff Layton } 44272ad94ae6SAl Viro exit: 44281da177e4SLinus Torvalds return error; 44291da177e4SLinus Torvalds } 44301da177e4SLinus Torvalds 4431520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4432520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4433520c8b16SMiklos Szeredi { 4434520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4435520c8b16SMiklos Szeredi } 4436520c8b16SMiklos Szeredi 4437a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 44385590ff0dSUlrich Drepper { 4439520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 44405590ff0dSUlrich Drepper } 44415590ff0dSUlrich Drepper 4442787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4443787fb6bcSMiklos Szeredi { 4444787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4445787fb6bcSMiklos Szeredi if (error) 4446787fb6bcSMiklos Szeredi return error; 4447787fb6bcSMiklos Szeredi 4448787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4449787fb6bcSMiklos Szeredi return -EPERM; 4450787fb6bcSMiklos Szeredi 4451787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4452787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4453787fb6bcSMiklos Szeredi } 4454787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4455787fb6bcSMiklos Szeredi 44565d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 44571da177e4SLinus Torvalds { 44585d826c84SAl Viro int len = PTR_ERR(link); 44591da177e4SLinus Torvalds if (IS_ERR(link)) 44601da177e4SLinus Torvalds goto out; 44611da177e4SLinus Torvalds 44621da177e4SLinus Torvalds len = strlen(link); 44631da177e4SLinus Torvalds if (len > (unsigned) buflen) 44641da177e4SLinus Torvalds len = buflen; 44651da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 44661da177e4SLinus Torvalds len = -EFAULT; 44671da177e4SLinus Torvalds out: 44681da177e4SLinus Torvalds return len; 44691da177e4SLinus Torvalds } 44705d826c84SAl Viro EXPORT_SYMBOL(readlink_copy); 44711da177e4SLinus Torvalds 44721da177e4SLinus Torvalds /* 44731da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 44741da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 44751da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 44761da177e4SLinus Torvalds */ 44771da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44781da177e4SLinus Torvalds { 4479cc314eefSLinus Torvalds void *cookie; 4480d4dee48bSAl Viro const char *link = dentry->d_inode->i_link; 4481694a1764SMarcin Slusarz int res; 4482cc314eefSLinus Torvalds 4483d4dee48bSAl Viro if (!link) { 44846e77137bSAl Viro link = dentry->d_inode->i_op->follow_link(dentry, &cookie); 4485680baacbSAl Viro if (IS_ERR(link)) 4486680baacbSAl Viro return PTR_ERR(link); 4487d4dee48bSAl Viro } 4488680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 44896e77137bSAl Viro if (dentry->d_inode->i_op->put_link) 4490680baacbSAl Viro dentry->d_inode->i_op->put_link(dentry, cookie); 4491694a1764SMarcin Slusarz return res; 44921da177e4SLinus Torvalds } 44934d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 44941da177e4SLinus Torvalds 44951da177e4SLinus Torvalds /* get the link contents into pagecache */ 44961da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 44971da177e4SLinus Torvalds { 4498ebd09abbSDuane Griffin char *kaddr; 44991da177e4SLinus Torvalds struct page *page; 45001da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 4501090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 45021da177e4SLinus Torvalds if (IS_ERR(page)) 45036fe6900eSNick Piggin return (char*)page; 45041da177e4SLinus Torvalds *ppage = page; 4505ebd09abbSDuane Griffin kaddr = kmap(page); 4506ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 4507ebd09abbSDuane Griffin return kaddr; 45081da177e4SLinus Torvalds } 45091da177e4SLinus Torvalds 45101da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 45111da177e4SLinus Torvalds { 45121da177e4SLinus Torvalds struct page *page = NULL; 45135d826c84SAl Viro int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); 45141da177e4SLinus Torvalds if (page) { 45151da177e4SLinus Torvalds kunmap(page); 45161da177e4SLinus Torvalds page_cache_release(page); 45171da177e4SLinus Torvalds } 45181da177e4SLinus Torvalds return res; 45191da177e4SLinus Torvalds } 45204d359507SAl Viro EXPORT_SYMBOL(page_readlink); 45211da177e4SLinus Torvalds 45226e77137bSAl Viro const char *page_follow_link_light(struct dentry *dentry, void **cookie) 45231da177e4SLinus Torvalds { 4524cc314eefSLinus Torvalds struct page *page = NULL; 4525680baacbSAl Viro char *res = page_getlink(dentry, &page); 4526680baacbSAl Viro if (!IS_ERR(res)) 4527680baacbSAl Viro *cookie = page; 4528680baacbSAl Viro return res; 45291da177e4SLinus Torvalds } 45304d359507SAl Viro EXPORT_SYMBOL(page_follow_link_light); 45311da177e4SLinus Torvalds 4532680baacbSAl Viro void page_put_link(struct dentry *dentry, void *cookie) 45331da177e4SLinus Torvalds { 4534cc314eefSLinus Torvalds struct page *page = cookie; 45351da177e4SLinus Torvalds kunmap(page); 45361da177e4SLinus Torvalds page_cache_release(page); 45371da177e4SLinus Torvalds } 45384d359507SAl Viro EXPORT_SYMBOL(page_put_link); 45391da177e4SLinus Torvalds 454054566b2cSNick Piggin /* 454154566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 454254566b2cSNick Piggin */ 454354566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 45441da177e4SLinus Torvalds { 45451da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 45460adb25d2SKirill Korotaev struct page *page; 4547afddba49SNick Piggin void *fsdata; 4548beb497abSDmitriy Monakhov int err; 45491da177e4SLinus Torvalds char *kaddr; 455054566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 455154566b2cSNick Piggin if (nofs) 455254566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 45531da177e4SLinus Torvalds 45547e53cac4SNeilBrown retry: 4555afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 455654566b2cSNick Piggin flags, &page, &fsdata); 45571da177e4SLinus Torvalds if (err) 4558afddba49SNick Piggin goto fail; 4559afddba49SNick Piggin 4560e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 45611da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 4562e8e3c3d6SCong Wang kunmap_atomic(kaddr); 4563afddba49SNick Piggin 4564afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4565afddba49SNick Piggin page, fsdata); 45661da177e4SLinus Torvalds if (err < 0) 45671da177e4SLinus Torvalds goto fail; 4568afddba49SNick Piggin if (err < len-1) 4569afddba49SNick Piggin goto retry; 4570afddba49SNick Piggin 45711da177e4SLinus Torvalds mark_inode_dirty(inode); 45721da177e4SLinus Torvalds return 0; 45731da177e4SLinus Torvalds fail: 45741da177e4SLinus Torvalds return err; 45751da177e4SLinus Torvalds } 45764d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 45771da177e4SLinus Torvalds 45780adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 45790adb25d2SKirill Korotaev { 45800adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 458154566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 45820adb25d2SKirill Korotaev } 45834d359507SAl Viro EXPORT_SYMBOL(page_symlink); 45840adb25d2SKirill Korotaev 458592e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 45861da177e4SLinus Torvalds .readlink = generic_readlink, 45871da177e4SLinus Torvalds .follow_link = page_follow_link_light, 45881da177e4SLinus Torvalds .put_link = page_put_link, 45891da177e4SLinus Torvalds }; 45901da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4591