11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namei.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Some corrections by tytso. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 121da177e4SLinus Torvalds * lookup logic. 131da177e4SLinus Torvalds */ 141da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 151da177e4SLinus Torvalds */ 161da177e4SLinus Torvalds 171da177e4SLinus Torvalds #include <linux/init.h> 18630d9c47SPaul Gortmaker #include <linux/export.h> 1944696908SDavid S. Miller #include <linux/kernel.h> 201da177e4SLinus Torvalds #include <linux/slab.h> 211da177e4SLinus Torvalds #include <linux/fs.h> 221da177e4SLinus Torvalds #include <linux/namei.h> 231da177e4SLinus Torvalds #include <linux/pagemap.h> 240eeca283SRobert Love #include <linux/fsnotify.h> 251da177e4SLinus Torvalds #include <linux/personality.h> 261da177e4SLinus Torvalds #include <linux/security.h> 276146f0d5SMimi Zohar #include <linux/ima.h> 281da177e4SLinus Torvalds #include <linux/syscalls.h> 291da177e4SLinus Torvalds #include <linux/mount.h> 301da177e4SLinus Torvalds #include <linux/audit.h> 3116f7e0feSRandy Dunlap #include <linux/capability.h> 32834f2a4aSTrond Myklebust #include <linux/file.h> 335590ff0dSUlrich Drepper #include <linux/fcntl.h> 3408ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 355ad4e53bSAl Viro #include <linux/fs_struct.h> 36e77819e5SLinus Torvalds #include <linux/posix_acl.h> 3799d263d4SLinus Torvalds #include <linux/hash.h> 381da177e4SLinus Torvalds #include <asm/uaccess.h> 391da177e4SLinus Torvalds 40e81e3f4dSEric Paris #include "internal.h" 41c7105365SAl Viro #include "mount.h" 42e81e3f4dSEric Paris 431da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 441da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 451da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 461da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 471da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 481da177e4SLinus Torvalds * 491da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 501da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 511da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 521da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 531da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 541da177e4SLinus Torvalds * the special cases of the former code. 551da177e4SLinus Torvalds * 561da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 571da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 581da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 591da177e4SLinus Torvalds * 601da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 611da177e4SLinus Torvalds * resolution to correspond with current state of the code. 621da177e4SLinus Torvalds * 631da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 641da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 651da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 661da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 671da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 681da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 691da177e4SLinus Torvalds */ 701da177e4SLinus Torvalds 711da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 721da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 731da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 741da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 751da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 761da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7725985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 781da177e4SLinus Torvalds * 791da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 801da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 811da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 821da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 831da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 841da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 851da177e4SLinus Torvalds * and in the old Linux semantics. 861da177e4SLinus Torvalds */ 871da177e4SLinus Torvalds 881da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 891da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 901da177e4SLinus Torvalds * 911da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 921da177e4SLinus Torvalds */ 931da177e4SLinus Torvalds 941da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 951da177e4SLinus Torvalds * inside the path - always follow. 961da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 971da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 981da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 991da177e4SLinus Torvalds * otherwise - don't follow. 1001da177e4SLinus Torvalds * (applied in that order). 1011da177e4SLinus Torvalds * 1021da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1031da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1041da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1051da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1061da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1071da177e4SLinus Torvalds */ 1081da177e4SLinus Torvalds /* 1091da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 110a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1111da177e4SLinus Torvalds * any extra contention... 1121da177e4SLinus Torvalds */ 1131da177e4SLinus Torvalds 1141da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1151da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1161da177e4SLinus Torvalds * kernel data space before using them.. 1171da177e4SLinus Torvalds * 1181da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1191da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1201da177e4SLinus Torvalds */ 1217950e385SJeff Layton 122fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12391a27b2aSJeff Layton 12451f39a1fSDavid Drysdale struct filename * 12591a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12691a27b2aSJeff Layton { 12794b5d262SAl Viro struct filename *result; 1287950e385SJeff Layton char *kname; 12994b5d262SAl Viro int len; 1301da177e4SLinus Torvalds 1317ac86265SJeff Layton result = audit_reusename(filename); 1327ac86265SJeff Layton if (result) 1337ac86265SJeff Layton return result; 1347ac86265SJeff Layton 1357950e385SJeff Layton result = __getname(); 1363f9f0aa6SLinus Torvalds if (unlikely(!result)) 1374043cde8SEric Paris return ERR_PTR(-ENOMEM); 1381da177e4SLinus Torvalds 1397950e385SJeff Layton /* 1407950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1417950e385SJeff Layton * allocation 1427950e385SJeff Layton */ 143fd2f7cb5SAl Viro kname = (char *)result->iname; 14491a27b2aSJeff Layton result->name = kname; 1457950e385SJeff Layton 14694b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 14791a27b2aSJeff Layton if (unlikely(len < 0)) { 14894b5d262SAl Viro __putname(result); 14994b5d262SAl Viro return ERR_PTR(len); 15091a27b2aSJeff Layton } 1513f9f0aa6SLinus Torvalds 1527950e385SJeff Layton /* 1537950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1547950e385SJeff Layton * separate struct filename so we can dedicate the entire 1557950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1567950e385SJeff Layton * userland. 1577950e385SJeff Layton */ 15894b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 159fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1607950e385SJeff Layton kname = (char *)result; 1617950e385SJeff Layton 162fd2f7cb5SAl Viro /* 163fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 164fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 165fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 166fd2f7cb5SAl Viro */ 167fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 16894b5d262SAl Viro if (unlikely(!result)) { 16994b5d262SAl Viro __putname(kname); 17094b5d262SAl Viro return ERR_PTR(-ENOMEM); 1717950e385SJeff Layton } 1727950e385SJeff Layton result->name = kname; 17394b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17494b5d262SAl Viro if (unlikely(len < 0)) { 17594b5d262SAl Viro __putname(kname); 17694b5d262SAl Viro kfree(result); 17794b5d262SAl Viro return ERR_PTR(len); 17894b5d262SAl Viro } 17994b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18094b5d262SAl Viro __putname(kname); 18194b5d262SAl Viro kfree(result); 18294b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18394b5d262SAl Viro } 1847950e385SJeff Layton } 1857950e385SJeff Layton 18694b5d262SAl Viro result->refcnt = 1; 1873f9f0aa6SLinus Torvalds /* The empty path is special. */ 1883f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1893f9f0aa6SLinus Torvalds if (empty) 1901fa1e7f6SAndy Whitcroft *empty = 1; 19194b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19294b5d262SAl Viro putname(result); 19394b5d262SAl Viro return ERR_PTR(-ENOENT); 1941da177e4SLinus Torvalds } 19594b5d262SAl Viro } 1967950e385SJeff Layton 1977950e385SJeff Layton result->uptr = filename; 198c4ad8f98SLinus Torvalds result->aname = NULL; 1991da177e4SLinus Torvalds audit_getname(result); 2001da177e4SLinus Torvalds return result; 2013f9f0aa6SLinus Torvalds } 2023f9f0aa6SLinus Torvalds 20391a27b2aSJeff Layton struct filename * 20491a27b2aSJeff Layton getname(const char __user * filename) 205f52e0c11SAl Viro { 206f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 207f52e0c11SAl Viro } 208f52e0c11SAl Viro 209c4ad8f98SLinus Torvalds struct filename * 210c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 211c4ad8f98SLinus Torvalds { 212c4ad8f98SLinus Torvalds struct filename *result; 21308518549SPaul Moore int len = strlen(filename) + 1; 214c4ad8f98SLinus Torvalds 215c4ad8f98SLinus Torvalds result = __getname(); 216c4ad8f98SLinus Torvalds if (unlikely(!result)) 217c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 218c4ad8f98SLinus Torvalds 21908518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 220fd2f7cb5SAl Viro result->name = (char *)result->iname; 22108518549SPaul Moore } else if (len <= PATH_MAX) { 22208518549SPaul Moore struct filename *tmp; 22308518549SPaul Moore 22408518549SPaul Moore tmp = kmalloc(sizeof(*tmp), GFP_KERNEL); 22508518549SPaul Moore if (unlikely(!tmp)) { 22608518549SPaul Moore __putname(result); 22708518549SPaul Moore return ERR_PTR(-ENOMEM); 22808518549SPaul Moore } 22908518549SPaul Moore tmp->name = (char *)result; 23008518549SPaul Moore result = tmp; 23108518549SPaul Moore } else { 23208518549SPaul Moore __putname(result); 23308518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23408518549SPaul Moore } 23508518549SPaul Moore memcpy((char *)result->name, filename, len); 236c4ad8f98SLinus Torvalds result->uptr = NULL; 237c4ad8f98SLinus Torvalds result->aname = NULL; 23855422d0bSPaul Moore result->refcnt = 1; 239fd3522fdSPaul Moore audit_getname(result); 240c4ad8f98SLinus Torvalds 241c4ad8f98SLinus Torvalds return result; 242c4ad8f98SLinus Torvalds } 243c4ad8f98SLinus Torvalds 24491a27b2aSJeff Layton void putname(struct filename *name) 2451da177e4SLinus Torvalds { 24655422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 24755422d0bSPaul Moore 24855422d0bSPaul Moore if (--name->refcnt > 0) 24955422d0bSPaul Moore return; 25055422d0bSPaul Moore 251fd2f7cb5SAl Viro if (name->name != name->iname) { 25255422d0bSPaul Moore __putname(name->name); 25355422d0bSPaul Moore kfree(name); 25455422d0bSPaul Moore } else 25555422d0bSPaul Moore __putname(name); 2561da177e4SLinus Torvalds } 2571da177e4SLinus Torvalds 258e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 259e77819e5SLinus Torvalds { 26084635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 261e77819e5SLinus Torvalds struct posix_acl *acl; 262e77819e5SLinus Torvalds 263e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2643567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2653567866bSAl Viro if (!acl) 266e77819e5SLinus Torvalds return -EAGAIN; 2673567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 2683567866bSAl Viro if (acl == ACL_NOT_CACHED) 269e77819e5SLinus Torvalds return -ECHILD; 270206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 271e77819e5SLinus Torvalds } 272e77819e5SLinus Torvalds 2732982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2744e34e719SChristoph Hellwig if (IS_ERR(acl)) 2754e34e719SChristoph Hellwig return PTR_ERR(acl); 276e77819e5SLinus Torvalds if (acl) { 277e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 278e77819e5SLinus Torvalds posix_acl_release(acl); 279e77819e5SLinus Torvalds return error; 280e77819e5SLinus Torvalds } 28184635d68SLinus Torvalds #endif 282e77819e5SLinus Torvalds 283e77819e5SLinus Torvalds return -EAGAIN; 284e77819e5SLinus Torvalds } 285e77819e5SLinus Torvalds 2865909ccaaSLinus Torvalds /* 287948409c7SAndreas Gruenbacher * This does the basic permission checking 2885909ccaaSLinus Torvalds */ 2897e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2905909ccaaSLinus Torvalds { 29126cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2925909ccaaSLinus Torvalds 2938e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2945909ccaaSLinus Torvalds mode >>= 6; 2955909ccaaSLinus Torvalds else { 296e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2977e40145eSAl Viro int error = check_acl(inode, mask); 2985909ccaaSLinus Torvalds if (error != -EAGAIN) 2995909ccaaSLinus Torvalds return error; 3005909ccaaSLinus Torvalds } 3015909ccaaSLinus Torvalds 3025909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3035909ccaaSLinus Torvalds mode >>= 3; 3045909ccaaSLinus Torvalds } 3055909ccaaSLinus Torvalds 3065909ccaaSLinus Torvalds /* 3075909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3085909ccaaSLinus Torvalds */ 3099c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3105909ccaaSLinus Torvalds return 0; 3115909ccaaSLinus Torvalds return -EACCES; 3125909ccaaSLinus Torvalds } 3131da177e4SLinus Torvalds 3141da177e4SLinus Torvalds /** 3151da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3161da177e4SLinus Torvalds * @inode: inode to check access rights for 3178fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3181da177e4SLinus Torvalds * 3191da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3201da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3211da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 322b74c79e9SNick Piggin * are used for other things. 323b74c79e9SNick Piggin * 324b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 325b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 326b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3271da177e4SLinus Torvalds */ 3282830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3291da177e4SLinus Torvalds { 3305909ccaaSLinus Torvalds int ret; 3311da177e4SLinus Torvalds 3321da177e4SLinus Torvalds /* 333948409c7SAndreas Gruenbacher * Do the basic permission checks. 3341da177e4SLinus Torvalds */ 3357e40145eSAl Viro ret = acl_permission_check(inode, mask); 3365909ccaaSLinus Torvalds if (ret != -EACCES) 3375909ccaaSLinus Torvalds return ret; 3381da177e4SLinus Torvalds 339d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 340d594e7ecSAl Viro /* DACs are overridable for directories */ 34123adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 342d594e7ecSAl Viro return 0; 343d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34423adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34523adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 346d594e7ecSAl Viro return 0; 347d594e7ecSAl Viro return -EACCES; 348d594e7ecSAl Viro } 3491da177e4SLinus Torvalds /* 3501da177e4SLinus Torvalds * Read/write DACs are always overridable. 351d594e7ecSAl Viro * Executable DACs are overridable when there is 352d594e7ecSAl Viro * at least one exec bit set. 3531da177e4SLinus Torvalds */ 354d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 35523adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3561da177e4SLinus Torvalds return 0; 3571da177e4SLinus Torvalds 3581da177e4SLinus Torvalds /* 3591da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3601da177e4SLinus Torvalds */ 3617ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 362d594e7ecSAl Viro if (mask == MAY_READ) 36323adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3641da177e4SLinus Torvalds return 0; 3651da177e4SLinus Torvalds 3661da177e4SLinus Torvalds return -EACCES; 3671da177e4SLinus Torvalds } 3684d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3691da177e4SLinus Torvalds 3703ddcd056SLinus Torvalds /* 3713ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3723ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3733ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3743ddcd056SLinus Torvalds * permission function, use the fast case". 3753ddcd056SLinus Torvalds */ 3763ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3773ddcd056SLinus Torvalds { 3783ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3793ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3803ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3813ddcd056SLinus Torvalds 3823ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3833ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3843ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3853ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3863ddcd056SLinus Torvalds } 3873ddcd056SLinus Torvalds return generic_permission(inode, mask); 3883ddcd056SLinus Torvalds } 3893ddcd056SLinus Torvalds 390cb23beb5SChristoph Hellwig /** 3910bdaea90SDavid Howells * __inode_permission - Check for access rights to a given inode 3920bdaea90SDavid Howells * @inode: Inode to check permission on 3930bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 394cb23beb5SChristoph Hellwig * 3950bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. 396948409c7SAndreas Gruenbacher * 397948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 3980bdaea90SDavid Howells * 3990bdaea90SDavid Howells * This does not check for a read-only file system. You probably want 4000bdaea90SDavid Howells * inode_permission(). 401cb23beb5SChristoph Hellwig */ 4020bdaea90SDavid Howells int __inode_permission(struct inode *inode, int mask) 4031da177e4SLinus Torvalds { 404e6305c43SAl Viro int retval; 4051da177e4SLinus Torvalds 4063ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 4071da177e4SLinus Torvalds /* 4081da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 4091da177e4SLinus Torvalds */ 4101da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 4111da177e4SLinus Torvalds return -EACCES; 4121da177e4SLinus Torvalds } 4131da177e4SLinus Torvalds 4143ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 4151da177e4SLinus Torvalds if (retval) 4161da177e4SLinus Torvalds return retval; 4171da177e4SLinus Torvalds 41808ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 41908ce5f16SSerge E. Hallyn if (retval) 42008ce5f16SSerge E. Hallyn return retval; 42108ce5f16SSerge E. Hallyn 422d09ca739SEric Paris return security_inode_permission(inode, mask); 4231da177e4SLinus Torvalds } 424bd5d0856SMiklos Szeredi EXPORT_SYMBOL(__inode_permission); 4251da177e4SLinus Torvalds 426f4d6ff89SAl Viro /** 4270bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 4280bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 42955852635SRandy Dunlap * @inode: Inode to check permission on 4300bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4310bdaea90SDavid Howells * 4320bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4330bdaea90SDavid Howells */ 4340bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4350bdaea90SDavid Howells { 4360bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4370bdaea90SDavid Howells umode_t mode = inode->i_mode; 4380bdaea90SDavid Howells 4390bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 4400bdaea90SDavid Howells if ((sb->s_flags & MS_RDONLY) && 4410bdaea90SDavid Howells (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4420bdaea90SDavid Howells return -EROFS; 4430bdaea90SDavid Howells } 4440bdaea90SDavid Howells return 0; 4450bdaea90SDavid Howells } 4460bdaea90SDavid Howells 4470bdaea90SDavid Howells /** 4480bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4490bdaea90SDavid Howells * @inode: Inode to check permission on 4500bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4510bdaea90SDavid Howells * 4520bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4530bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4540bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4550bdaea90SDavid Howells * 4560bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4570bdaea90SDavid Howells */ 4580bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4590bdaea90SDavid Howells { 4600bdaea90SDavid Howells int retval; 4610bdaea90SDavid Howells 4620bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4630bdaea90SDavid Howells if (retval) 4640bdaea90SDavid Howells return retval; 4650bdaea90SDavid Howells return __inode_permission(inode, mask); 4660bdaea90SDavid Howells } 4674d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4680bdaea90SDavid Howells 4690bdaea90SDavid Howells /** 4705dd784d0SJan Blunck * path_get - get a reference to a path 4715dd784d0SJan Blunck * @path: path to get the reference to 4725dd784d0SJan Blunck * 4735dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4745dd784d0SJan Blunck */ 475dcf787f3SAl Viro void path_get(const struct path *path) 4765dd784d0SJan Blunck { 4775dd784d0SJan Blunck mntget(path->mnt); 4785dd784d0SJan Blunck dget(path->dentry); 4795dd784d0SJan Blunck } 4805dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4815dd784d0SJan Blunck 4825dd784d0SJan Blunck /** 4831d957f9bSJan Blunck * path_put - put a reference to a path 4841d957f9bSJan Blunck * @path: path to put the reference to 4851d957f9bSJan Blunck * 4861d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4871d957f9bSJan Blunck */ 488dcf787f3SAl Viro void path_put(const struct path *path) 4891da177e4SLinus Torvalds { 4901d957f9bSJan Blunck dput(path->dentry); 4911d957f9bSJan Blunck mntput(path->mnt); 4921da177e4SLinus Torvalds } 4931d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4941da177e4SLinus Torvalds 495894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 4961f55a6ecSAl Viro struct nameidata { 4971f55a6ecSAl Viro struct path path; 4981f55a6ecSAl Viro struct qstr last; 4991f55a6ecSAl Viro struct path root; 5001f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 5011f55a6ecSAl Viro unsigned int flags; 5021f55a6ecSAl Viro unsigned seq, m_seq; 5031f55a6ecSAl Viro int last_type; 5041f55a6ecSAl Viro unsigned depth; 505756daf26SNeilBrown int total_link_count; 506697fc6caSAl Viro struct saved { 507697fc6caSAl Viro struct path link; 508697fc6caSAl Viro void *cookie; 509697fc6caSAl Viro const char *name; 510237d8b32SAl Viro struct inode *inode; 5110450b2d1SAl Viro unsigned seq; 512894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5131f55a6ecSAl Viro }; 5141f55a6ecSAl Viro 515756daf26SNeilBrown static struct nameidata *set_nameidata(struct nameidata *p) 516894bc8c4SAl Viro { 517756daf26SNeilBrown struct nameidata *old = current->nameidata; 518756daf26SNeilBrown p->stack = p->internal; 519756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 520756daf26SNeilBrown current->nameidata = p; 521756daf26SNeilBrown return old; 522894bc8c4SAl Viro } 523894bc8c4SAl Viro 524756daf26SNeilBrown static void restore_nameidata(struct nameidata *old) 525894bc8c4SAl Viro { 526756daf26SNeilBrown struct nameidata *now = current->nameidata; 527756daf26SNeilBrown 528756daf26SNeilBrown current->nameidata = old; 529756daf26SNeilBrown if (old) 530756daf26SNeilBrown old->total_link_count = now->total_link_count; 531756daf26SNeilBrown if (now->stack != now->internal) { 532756daf26SNeilBrown kfree(now->stack); 533756daf26SNeilBrown now->stack = now->internal; 534894bc8c4SAl Viro } 535894bc8c4SAl Viro } 536894bc8c4SAl Viro 537894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 538894bc8c4SAl Viro { 539e269f2a7SAl Viro struct saved *p = kmalloc(MAXSYMLINKS * sizeof(struct saved), 540894bc8c4SAl Viro GFP_KERNEL); 541894bc8c4SAl Viro if (unlikely(!p)) 542894bc8c4SAl Viro return -ENOMEM; 543894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 544894bc8c4SAl Viro nd->stack = p; 545894bc8c4SAl Viro return 0; 546894bc8c4SAl Viro } 547894bc8c4SAl Viro 548894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 549894bc8c4SAl Viro { 550da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 551894bc8c4SAl Viro return 0; 552894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 553894bc8c4SAl Viro return 0; 554894bc8c4SAl Viro return __nd_alloc_stack(nd); 555894bc8c4SAl Viro } 556894bc8c4SAl Viro 5577973387aSAl Viro static void drop_links(struct nameidata *nd) 5587973387aSAl Viro { 5597973387aSAl Viro int i = nd->depth; 5607973387aSAl Viro while (i--) { 5617973387aSAl Viro struct saved *last = nd->stack + i; 5627973387aSAl Viro struct inode *inode = last->inode; 5637973387aSAl Viro if (last->cookie && inode->i_op->put_link) { 5647973387aSAl Viro inode->i_op->put_link(inode, last->cookie); 5657973387aSAl Viro last->cookie = NULL; 5667973387aSAl Viro } 5677973387aSAl Viro } 5687973387aSAl Viro } 5697973387aSAl Viro 5707973387aSAl Viro static void terminate_walk(struct nameidata *nd) 5717973387aSAl Viro { 5727973387aSAl Viro drop_links(nd); 5737973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 5747973387aSAl Viro int i; 5757973387aSAl Viro path_put(&nd->path); 5767973387aSAl Viro for (i = 0; i < nd->depth; i++) 5777973387aSAl Viro path_put(&nd->stack[i].link); 5787973387aSAl Viro } else { 5797973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 5807973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 5817973387aSAl Viro nd->root.mnt = NULL; 5827973387aSAl Viro rcu_read_unlock(); 5837973387aSAl Viro } 5847973387aSAl Viro nd->depth = 0; 5857973387aSAl Viro } 5867973387aSAl Viro 5877973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 5887973387aSAl Viro static bool legitimize_path(struct nameidata *nd, 5897973387aSAl Viro struct path *path, unsigned seq) 5907973387aSAl Viro { 5917973387aSAl Viro int res = __legitimize_mnt(path->mnt, nd->m_seq); 5927973387aSAl Viro if (unlikely(res)) { 5937973387aSAl Viro if (res > 0) 5947973387aSAl Viro path->mnt = NULL; 5957973387aSAl Viro path->dentry = NULL; 5967973387aSAl Viro return false; 5977973387aSAl Viro } 5987973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 5997973387aSAl Viro path->dentry = NULL; 6007973387aSAl Viro return false; 6017973387aSAl Viro } 6027973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6037973387aSAl Viro } 6047973387aSAl Viro 6057973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6067973387aSAl Viro { 6077973387aSAl Viro int i; 6087973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6097973387aSAl Viro struct saved *last = nd->stack + i; 6107973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6117973387aSAl Viro drop_links(nd); 6127973387aSAl Viro nd->depth = i + 1; 6137973387aSAl Viro return false; 6147973387aSAl Viro } 6157973387aSAl Viro } 6167973387aSAl Viro return true; 6177973387aSAl Viro } 6187973387aSAl Viro 61919660af7SAl Viro /* 62031e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 62119660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 62219660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 62319660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 62419660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 62519660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 62619660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 62719660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 62831e6b01fSNick Piggin */ 62931e6b01fSNick Piggin 63031e6b01fSNick Piggin /** 63119660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 63219660af7SAl Viro * @nd: nameidata pathwalk data 63319660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 6346e9918b7SAl Viro * @seq: seq number to check dentry against 63539191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 63631e6b01fSNick Piggin * 63719660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 63819660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 63919660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 6407973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6417973387aSAl Viro * terminate_walk(). 64231e6b01fSNick Piggin */ 6436e9918b7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry, unsigned seq) 64431e6b01fSNick Piggin { 64531e6b01fSNick Piggin struct fs_struct *fs = current->fs; 64631e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 64731e6b01fSNick Piggin 64831e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 649e5c832d5SLinus Torvalds 650e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6517973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6527973387aSAl Viro goto out2; 6537973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 6547973387aSAl Viro goto out2; 6557973387aSAl Viro if (unlikely(!lockref_get_not_dead(&parent->d_lockref))) 6567973387aSAl Viro goto out1; 65748a066e7SAl Viro 65815570086SLinus Torvalds /* 65915570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 66015570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 66115570086SLinus Torvalds * 66215570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 66315570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 66415570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 66515570086SLinus Torvalds * since we checked the sequence number of the parent after we got 66615570086SLinus Torvalds * the child sequence number. So we know the parent must still 66715570086SLinus Torvalds * be valid if the child sequence number is still valid. 66815570086SLinus Torvalds */ 66919660af7SAl Viro if (!dentry) { 670e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 671e5c832d5SLinus Torvalds goto out; 67219660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 67319660af7SAl Viro } else { 674e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 675e5c832d5SLinus Torvalds goto out; 6766e9918b7SAl Viro if (read_seqcount_retry(&dentry->d_seq, seq)) 677e5c832d5SLinus Torvalds goto drop_dentry; 67819660af7SAl Viro } 679e5c832d5SLinus Torvalds 680e5c832d5SLinus Torvalds /* 681e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 682e5c832d5SLinus Torvalds * still valid and get it if required. 683e5c832d5SLinus Torvalds */ 684e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 685e5c832d5SLinus Torvalds spin_lock(&fs->lock); 6867973387aSAl Viro if (unlikely(!path_equal(&nd->root, &fs->root))) { 6877973387aSAl Viro spin_unlock(&fs->lock); 6887973387aSAl Viro goto drop_dentry; 6897973387aSAl Viro } 69031e6b01fSNick Piggin path_get(&nd->root); 69131e6b01fSNick Piggin spin_unlock(&fs->lock); 69231e6b01fSNick Piggin } 69331e6b01fSNick Piggin 6948b61e74fSAl Viro rcu_read_unlock(); 69531e6b01fSNick Piggin return 0; 69619660af7SAl Viro 697e5c832d5SLinus Torvalds drop_dentry: 6988b61e74fSAl Viro rcu_read_unlock(); 699e5c832d5SLinus Torvalds dput(dentry); 700d0d27277SLinus Torvalds goto drop_root_mnt; 7017973387aSAl Viro out2: 7027973387aSAl Viro nd->path.mnt = NULL; 7037973387aSAl Viro out1: 7047973387aSAl Viro nd->path.dentry = NULL; 705e5c832d5SLinus Torvalds out: 7068b61e74fSAl Viro rcu_read_unlock(); 707d0d27277SLinus Torvalds drop_root_mnt: 708d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 709d0d27277SLinus Torvalds nd->root.mnt = NULL; 71031e6b01fSNick Piggin return -ECHILD; 71131e6b01fSNick Piggin } 71231e6b01fSNick Piggin 7137973387aSAl Viro static int unlazy_link(struct nameidata *nd, struct path *link, unsigned seq) 7147973387aSAl Viro { 7157973387aSAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 7167973387aSAl Viro drop_links(nd); 7177973387aSAl Viro nd->depth = 0; 7187973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 7197973387aSAl Viro nd->path.mnt = NULL; 7207973387aSAl Viro nd->path.dentry = NULL; 7217973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7227973387aSAl Viro nd->root.mnt = NULL; 7237973387aSAl Viro rcu_read_unlock(); 7247973387aSAl Viro } else if (likely(unlazy_walk(nd, NULL, 0)) == 0) { 7257973387aSAl Viro return 0; 7267973387aSAl Viro } 7277973387aSAl Viro path_put(link); 7287973387aSAl Viro return -ECHILD; 7297973387aSAl Viro } 7307973387aSAl Viro 7314ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 73234286d66SNick Piggin { 7334ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 73434286d66SNick Piggin } 73534286d66SNick Piggin 7369f1fafeeSAl Viro /** 7379f1fafeeSAl Viro * complete_walk - successful completion of path walk 7389f1fafeeSAl Viro * @nd: pointer nameidata 73939159de2SJeff Layton * 7409f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7419f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7429f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7439f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7449f1fafeeSAl Viro * need to drop nd->path. 74539159de2SJeff Layton */ 7469f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 74739159de2SJeff Layton { 74816c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 74939159de2SJeff Layton int status; 75039159de2SJeff Layton 7519f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 7529f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7539f1fafeeSAl Viro nd->root.mnt = NULL; 7546e9918b7SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 75548a066e7SAl Viro return -ECHILD; 75648a066e7SAl Viro } 7579f1fafeeSAl Viro 75816c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 75939159de2SJeff Layton return 0; 76039159de2SJeff Layton 761ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 76216c2cd71SAl Viro return 0; 76316c2cd71SAl Viro 764ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 76539159de2SJeff Layton if (status > 0) 76639159de2SJeff Layton return 0; 76739159de2SJeff Layton 76816c2cd71SAl Viro if (!status) 76939159de2SJeff Layton status = -ESTALE; 77016c2cd71SAl Viro 77139159de2SJeff Layton return status; 77239159de2SJeff Layton } 77339159de2SJeff Layton 7742a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 7752a737871SAl Viro { 776f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 7772a737871SAl Viro } 7782a737871SAl Viro 7797bd88377SAl Viro static __always_inline unsigned set_root_rcu(struct nameidata *nd) 78031e6b01fSNick Piggin { 78131e6b01fSNick Piggin struct fs_struct *fs = current->fs; 7827bd88377SAl Viro unsigned seq, res; 783c28cc364SNick Piggin 784c28cc364SNick Piggin do { 785c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 78631e6b01fSNick Piggin nd->root = fs->root; 7877bd88377SAl Viro res = __read_seqcount_begin(&nd->root.dentry->d_seq); 788c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 7897bd88377SAl Viro return res; 79031e6b01fSNick Piggin } 79131e6b01fSNick Piggin 7921d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 793051d3812SIan Kent { 794051d3812SIan Kent dput(path->dentry); 7954ac91378SJan Blunck if (path->mnt != nd->path.mnt) 796051d3812SIan Kent mntput(path->mnt); 797051d3812SIan Kent } 798051d3812SIan Kent 7997b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8007b9337aaSNick Piggin struct nameidata *nd) 801051d3812SIan Kent { 80231e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8034ac91378SJan Blunck dput(nd->path.dentry); 80431e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8054ac91378SJan Blunck mntput(nd->path.mnt); 8069a229683SHuang Shijie } 80731e6b01fSNick Piggin nd->path.mnt = path->mnt; 8084ac91378SJan Blunck nd->path.dentry = path->dentry; 809051d3812SIan Kent } 810051d3812SIan Kent 811b5fb63c1SChristoph Hellwig /* 812b5fb63c1SChristoph Hellwig * Helper to directly jump to a known parsed path from ->follow_link, 813b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 814b5fb63c1SChristoph Hellwig */ 8156e77137bSAl Viro void nd_jump_link(struct path *path) 816b5fb63c1SChristoph Hellwig { 8176e77137bSAl Viro struct nameidata *nd = current->nameidata; 818b5fb63c1SChristoph Hellwig path_put(&nd->path); 819b5fb63c1SChristoph Hellwig 820b5fb63c1SChristoph Hellwig nd->path = *path; 821b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 822b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 823b5fb63c1SChristoph Hellwig } 824b5fb63c1SChristoph Hellwig 825b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 826574197e0SAl Viro { 82721c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 828237d8b32SAl Viro struct inode *inode = last->inode; 829b9ff4429SAl Viro if (last->cookie && inode->i_op->put_link) 8305f2c4179SAl Viro inode->i_op->put_link(inode, last->cookie); 8316548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 832b9ff4429SAl Viro path_put(&last->link); 833574197e0SAl Viro } 834574197e0SAl Viro 835561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 836561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 837800179c9SKees Cook 838800179c9SKees Cook /** 839800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 84055852635SRandy Dunlap * @nd: nameidata pathwalk data 841800179c9SKees Cook * 842800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 843800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 844800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 845800179c9SKees Cook * processes from failing races against path names that may change out 846800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 847800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 848800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 849800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 850800179c9SKees Cook * 851800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 852800179c9SKees Cook */ 853fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 854800179c9SKees Cook { 855800179c9SKees Cook const struct inode *inode; 856800179c9SKees Cook const struct inode *parent; 857800179c9SKees Cook 858800179c9SKees Cook if (!sysctl_protected_symlinks) 859800179c9SKees Cook return 0; 860800179c9SKees Cook 861800179c9SKees Cook /* Allowed if owner and follower match. */ 862237d8b32SAl Viro inode = nd->stack[0].inode; 86381abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 864800179c9SKees Cook return 0; 865800179c9SKees Cook 866800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 867800179c9SKees Cook parent = nd->path.dentry->d_inode; 868800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 869800179c9SKees Cook return 0; 870800179c9SKees Cook 871800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 87281abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 873800179c9SKees Cook return 0; 874800179c9SKees Cook 87531956502SAl Viro if (nd->flags & LOOKUP_RCU) 87631956502SAl Viro return -ECHILD; 87731956502SAl Viro 8781cf2665bSAl Viro audit_log_link_denied("follow_link", &nd->stack[0].link); 879800179c9SKees Cook return -EACCES; 880800179c9SKees Cook } 881800179c9SKees Cook 882800179c9SKees Cook /** 883800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 884800179c9SKees Cook * @inode: the source inode to hardlink from 885800179c9SKees Cook * 886800179c9SKees Cook * Return false if at least one of the following conditions: 887800179c9SKees Cook * - inode is not a regular file 888800179c9SKees Cook * - inode is setuid 889800179c9SKees Cook * - inode is setgid and group-exec 890800179c9SKees Cook * - access failure for read and write 891800179c9SKees Cook * 892800179c9SKees Cook * Otherwise returns true. 893800179c9SKees Cook */ 894800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 895800179c9SKees Cook { 896800179c9SKees Cook umode_t mode = inode->i_mode; 897800179c9SKees Cook 898800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 899800179c9SKees Cook if (!S_ISREG(mode)) 900800179c9SKees Cook return false; 901800179c9SKees Cook 902800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 903800179c9SKees Cook if (mode & S_ISUID) 904800179c9SKees Cook return false; 905800179c9SKees Cook 906800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 907800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 908800179c9SKees Cook return false; 909800179c9SKees Cook 910800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 911800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 912800179c9SKees Cook return false; 913800179c9SKees Cook 914800179c9SKees Cook return true; 915800179c9SKees Cook } 916800179c9SKees Cook 917800179c9SKees Cook /** 918800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 919800179c9SKees Cook * @link: the source to hardlink from 920800179c9SKees Cook * 921800179c9SKees Cook * Block hardlink when all of: 922800179c9SKees Cook * - sysctl_protected_hardlinks enabled 923800179c9SKees Cook * - fsuid does not match inode 924800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 925800179c9SKees Cook * - not CAP_FOWNER 926800179c9SKees Cook * 927800179c9SKees Cook * Returns 0 if successful, -ve on error. 928800179c9SKees Cook */ 929800179c9SKees Cook static int may_linkat(struct path *link) 930800179c9SKees Cook { 931800179c9SKees Cook const struct cred *cred; 932800179c9SKees Cook struct inode *inode; 933800179c9SKees Cook 934800179c9SKees Cook if (!sysctl_protected_hardlinks) 935800179c9SKees Cook return 0; 936800179c9SKees Cook 937800179c9SKees Cook cred = current_cred(); 938800179c9SKees Cook inode = link->dentry->d_inode; 939800179c9SKees Cook 940800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 941800179c9SKees Cook * otherwise, it must be a safe source. 942800179c9SKees Cook */ 94381abe27bSEric W. Biederman if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || 944800179c9SKees Cook capable(CAP_FOWNER)) 945800179c9SKees Cook return 0; 946800179c9SKees Cook 947a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 948800179c9SKees Cook return -EPERM; 949800179c9SKees Cook } 950800179c9SKees Cook 9513b2e7f75SAl Viro static __always_inline 9523b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 9531da177e4SLinus Torvalds { 954ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 9551cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 956237d8b32SAl Viro struct inode *inode = last->inode; 9576d7b5aaeSAl Viro int error; 9580a959df5SAl Viro const char *res; 9591da177e4SLinus Torvalds 960844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 961844a3917SAl Viro 962574197e0SAl Viro cond_resched(); 963574197e0SAl Viro 9643b2e7f75SAl Viro touch_atime(&last->link); 965cd4e91d3SAl Viro 966bda0be7aSNeilBrown error = security_inode_follow_link(dentry, inode, 967bda0be7aSNeilBrown nd->flags & LOOKUP_RCU); 968bda0be7aSNeilBrown if (unlikely(error)) 9696920a440SAl Viro return ERR_PTR(error); 97036f3b4f6SAl Viro 97186acdca1SAl Viro nd->last_type = LAST_BIND; 972d4dee48bSAl Viro res = inode->i_link; 973d4dee48bSAl Viro if (!res) { 9746e77137bSAl Viro res = inode->i_op->follow_link(dentry, &last->cookie); 975fab51e8aSAl Viro if (IS_ERR_OR_NULL(res)) { 9766920a440SAl Viro last->cookie = NULL; 977fab51e8aSAl Viro return res; 9780a959df5SAl Viro } 979fab51e8aSAl Viro } 980fab51e8aSAl Viro if (*res == '/') { 981fab51e8aSAl Viro if (!nd->root.mnt) 982fab51e8aSAl Viro set_root(nd); 983fab51e8aSAl Viro path_put(&nd->path); 984fab51e8aSAl Viro nd->path = nd->root; 985fab51e8aSAl Viro path_get(&nd->root); 986fab51e8aSAl Viro nd->inode = nd->path.dentry->d_inode; 987fab51e8aSAl Viro nd->flags |= LOOKUP_JUMPED; 988fab51e8aSAl Viro while (unlikely(*++res == '/')) 989fab51e8aSAl Viro ; 990fab51e8aSAl Viro } 991fab51e8aSAl Viro if (!*res) 992fab51e8aSAl Viro res = NULL; 9930a959df5SAl Viro return res; 9940a959df5SAl Viro } 9956d7b5aaeSAl Viro 99631e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 99731e6b01fSNick Piggin { 9980714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9990714a533SAl Viro struct mount *parent; 100031e6b01fSNick Piggin struct dentry *mountpoint; 100131e6b01fSNick Piggin 10020714a533SAl Viro parent = mnt->mnt_parent; 10030714a533SAl Viro if (&parent->mnt == path->mnt) 100431e6b01fSNick Piggin return 0; 1005a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 100631e6b01fSNick Piggin path->dentry = mountpoint; 10070714a533SAl Viro path->mnt = &parent->mnt; 100831e6b01fSNick Piggin return 1; 100931e6b01fSNick Piggin } 101031e6b01fSNick Piggin 1011f015f126SDavid Howells /* 1012f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1013f015f126SDavid Howells * 1014f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1015f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1016f015f126SDavid Howells * Up is towards /. 1017f015f126SDavid Howells * 1018f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1019f015f126SDavid Howells * root. 1020f015f126SDavid Howells */ 1021bab77ebfSAl Viro int follow_up(struct path *path) 10221da177e4SLinus Torvalds { 10230714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 10240714a533SAl Viro struct mount *parent; 10251da177e4SLinus Torvalds struct dentry *mountpoint; 102699b7db7bSNick Piggin 102748a066e7SAl Viro read_seqlock_excl(&mount_lock); 10280714a533SAl Viro parent = mnt->mnt_parent; 10293c0a6163SAl Viro if (parent == mnt) { 103048a066e7SAl Viro read_sequnlock_excl(&mount_lock); 10311da177e4SLinus Torvalds return 0; 10321da177e4SLinus Torvalds } 10330714a533SAl Viro mntget(&parent->mnt); 1034a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 103548a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1036bab77ebfSAl Viro dput(path->dentry); 1037bab77ebfSAl Viro path->dentry = mountpoint; 1038bab77ebfSAl Viro mntput(path->mnt); 10390714a533SAl Viro path->mnt = &parent->mnt; 10401da177e4SLinus Torvalds return 1; 10411da177e4SLinus Torvalds } 10424d359507SAl Viro EXPORT_SYMBOL(follow_up); 10431da177e4SLinus Torvalds 1044b5c84bf6SNick Piggin /* 10459875cf80SDavid Howells * Perform an automount 10469875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 10479875cf80SDavid Howells * were called with. 10481da177e4SLinus Torvalds */ 1049756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 10509875cf80SDavid Howells bool *need_mntput) 105131e6b01fSNick Piggin { 10529875cf80SDavid Howells struct vfsmount *mnt; 1053ea5b778aSDavid Howells int err; 10549875cf80SDavid Howells 10559875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 10569875cf80SDavid Howells return -EREMOTE; 10579875cf80SDavid Howells 10580ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 10590ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 10600ec26fd0SMiklos Szeredi * the name. 10610ec26fd0SMiklos Szeredi * 10620ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 10635a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 10640ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 10650ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 10660ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 10670ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 10685a30d8a2SDavid Howells */ 1069756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 1070d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 10715a30d8a2SDavid Howells path->dentry->d_inode) 10729875cf80SDavid Howells return -EISDIR; 10730ec26fd0SMiklos Szeredi 1074756daf26SNeilBrown nd->total_link_count++; 1075756daf26SNeilBrown if (nd->total_link_count >= 40) 10769875cf80SDavid Howells return -ELOOP; 10779875cf80SDavid Howells 10789875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 10799875cf80SDavid Howells if (IS_ERR(mnt)) { 10809875cf80SDavid Howells /* 10819875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 10829875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 10839875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 10849875cf80SDavid Howells * 10859875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 10869875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 10879875cf80SDavid Howells * the path is inaccessible and we should say so. 10889875cf80SDavid Howells */ 1089756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 10909875cf80SDavid Howells return -EREMOTE; 10919875cf80SDavid Howells return PTR_ERR(mnt); 109231e6b01fSNick Piggin } 1093ea5b778aSDavid Howells 10949875cf80SDavid Howells if (!mnt) /* mount collision */ 10959875cf80SDavid Howells return 0; 10969875cf80SDavid Howells 10978aef1884SAl Viro if (!*need_mntput) { 10988aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 10998aef1884SAl Viro mntget(path->mnt); 11008aef1884SAl Viro *need_mntput = true; 11018aef1884SAl Viro } 110219a167afSAl Viro err = finish_automount(mnt, path); 1103ea5b778aSDavid Howells 1104ea5b778aSDavid Howells switch (err) { 1105ea5b778aSDavid Howells case -EBUSY: 1106ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 110719a167afSAl Viro return 0; 1108ea5b778aSDavid Howells case 0: 11098aef1884SAl Viro path_put(path); 11109875cf80SDavid Howells path->mnt = mnt; 11119875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 11129875cf80SDavid Howells return 0; 111319a167afSAl Viro default: 111419a167afSAl Viro return err; 11159875cf80SDavid Howells } 111619a167afSAl Viro 1117ea5b778aSDavid Howells } 11189875cf80SDavid Howells 11199875cf80SDavid Howells /* 11209875cf80SDavid Howells * Handle a dentry that is managed in some way. 1121cc53ce53SDavid Howells * - Flagged for transit management (autofs) 11229875cf80SDavid Howells * - Flagged as mountpoint 11239875cf80SDavid Howells * - Flagged as automount point 11249875cf80SDavid Howells * 11259875cf80SDavid Howells * This may only be called in refwalk mode. 11269875cf80SDavid Howells * 11279875cf80SDavid Howells * Serialization is taken care of in namespace.c 11289875cf80SDavid Howells */ 1129756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 11309875cf80SDavid Howells { 11318aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 11329875cf80SDavid Howells unsigned managed; 11339875cf80SDavid Howells bool need_mntput = false; 11348aef1884SAl Viro int ret = 0; 11359875cf80SDavid Howells 11369875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 11379875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 11389875cf80SDavid Howells * the components of that value change under us */ 11399875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 11409875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 11419875cf80SDavid Howells unlikely(managed != 0)) { 1142cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1143cc53ce53SDavid Howells * being held. */ 1144cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1145cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1146cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 11471aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1148cc53ce53SDavid Howells if (ret < 0) 11498aef1884SAl Viro break; 1150cc53ce53SDavid Howells } 1151cc53ce53SDavid Howells 11529875cf80SDavid Howells /* Transit to a mounted filesystem. */ 11539875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 11549875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 11559875cf80SDavid Howells if (mounted) { 11569875cf80SDavid Howells dput(path->dentry); 11579875cf80SDavid Howells if (need_mntput) 1158463ffb2eSAl Viro mntput(path->mnt); 1159463ffb2eSAl Viro path->mnt = mounted; 1160463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 11619875cf80SDavid Howells need_mntput = true; 11629875cf80SDavid Howells continue; 1163463ffb2eSAl Viro } 1164463ffb2eSAl Viro 11659875cf80SDavid Howells /* Something is mounted on this dentry in another 11669875cf80SDavid Howells * namespace and/or whatever was mounted there in this 116748a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 116848a066e7SAl Viro * get it */ 11691da177e4SLinus Torvalds } 11709875cf80SDavid Howells 11719875cf80SDavid Howells /* Handle an automount point */ 11729875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1173756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 11749875cf80SDavid Howells if (ret < 0) 11758aef1884SAl Viro break; 11769875cf80SDavid Howells continue; 11779875cf80SDavid Howells } 11789875cf80SDavid Howells 11799875cf80SDavid Howells /* We didn't change the current path point */ 11809875cf80SDavid Howells break; 11819875cf80SDavid Howells } 11828aef1884SAl Viro 11838aef1884SAl Viro if (need_mntput && path->mnt == mnt) 11848aef1884SAl Viro mntput(path->mnt); 11858aef1884SAl Viro if (ret == -EISDIR) 11868aef1884SAl Viro ret = 0; 11878402752eSAl Viro if (need_mntput) 11888402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 11898402752eSAl Viro if (unlikely(ret < 0)) 11908402752eSAl Viro path_put_conditional(path, nd); 11918402752eSAl Viro return ret; 11921da177e4SLinus Torvalds } 11931da177e4SLinus Torvalds 1194cc53ce53SDavid Howells int follow_down_one(struct path *path) 11951da177e4SLinus Torvalds { 11961da177e4SLinus Torvalds struct vfsmount *mounted; 11971da177e4SLinus Torvalds 11981c755af4SAl Viro mounted = lookup_mnt(path); 11991da177e4SLinus Torvalds if (mounted) { 12009393bd07SAl Viro dput(path->dentry); 12019393bd07SAl Viro mntput(path->mnt); 12029393bd07SAl Viro path->mnt = mounted; 12039393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12041da177e4SLinus Torvalds return 1; 12051da177e4SLinus Torvalds } 12061da177e4SLinus Torvalds return 0; 12071da177e4SLinus Torvalds } 12084d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12091da177e4SLinus Torvalds 1210b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 121162a7375eSIan Kent { 1212b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1213b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 121462a7375eSIan Kent } 121562a7375eSIan Kent 12169875cf80SDavid Howells /* 1217287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1218287548e4SAl Viro * we meet a managed dentry that would need blocking. 12199875cf80SDavid Howells */ 12209875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1221254cf582SAl Viro struct inode **inode, unsigned *seqp) 12229875cf80SDavid Howells { 122362a7375eSIan Kent for (;;) { 1224c7105365SAl Viro struct mount *mounted; 122562a7375eSIan Kent /* 122662a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 122762a7375eSIan Kent * that wants to block transit. 122862a7375eSIan Kent */ 1229b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1230b8faf035SNeilBrown case -ECHILD: 1231b8faf035SNeilBrown default: 1232ab90911fSDavid Howells return false; 1233b8faf035SNeilBrown case -EISDIR: 1234b8faf035SNeilBrown return true; 1235b8faf035SNeilBrown case 0: 1236b8faf035SNeilBrown break; 1237b8faf035SNeilBrown } 123862a7375eSIan Kent 123962a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1240b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 124162a7375eSIan Kent 1242474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 12439875cf80SDavid Howells if (!mounted) 12449875cf80SDavid Howells break; 1245c7105365SAl Viro path->mnt = &mounted->mnt; 1246c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1247a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1248254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 124959430262SLinus Torvalds /* 125059430262SLinus Torvalds * Update the inode too. We don't need to re-check the 125159430262SLinus Torvalds * dentry sequence number here after this d_inode read, 125259430262SLinus Torvalds * because a mount-point is always pinned. 125359430262SLinus Torvalds */ 125459430262SLinus Torvalds *inode = path->dentry->d_inode; 12559875cf80SDavid Howells } 1256f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1257b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1258287548e4SAl Viro } 1259287548e4SAl Viro 126031e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 126131e6b01fSNick Piggin { 12624023bfc9SAl Viro struct inode *inode = nd->inode; 12637bd88377SAl Viro if (!nd->root.mnt) 126431e6b01fSNick Piggin set_root_rcu(nd); 126531e6b01fSNick Piggin 126631e6b01fSNick Piggin while (1) { 126731e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 126831e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 126931e6b01fSNick Piggin break; 127031e6b01fSNick Piggin } 127131e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 127231e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 127331e6b01fSNick Piggin struct dentry *parent = old->d_parent; 127431e6b01fSNick Piggin unsigned seq; 127531e6b01fSNick Piggin 12764023bfc9SAl Viro inode = parent->d_inode; 127731e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 127831e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1279ef7562d5SAl Viro goto failed; 128031e6b01fSNick Piggin nd->path.dentry = parent; 128131e6b01fSNick Piggin nd->seq = seq; 128231e6b01fSNick Piggin break; 128331e6b01fSNick Piggin } 128431e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 128531e6b01fSNick Piggin break; 12864023bfc9SAl Viro inode = nd->path.dentry->d_inode; 128731e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 128831e6b01fSNick Piggin } 1289b37199e6SAl Viro while (d_mountpoint(nd->path.dentry)) { 1290b37199e6SAl Viro struct mount *mounted; 1291b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1292b37199e6SAl Viro if (!mounted) 1293b37199e6SAl Viro break; 1294b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1295b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 12964023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1297b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1298f5be3e29SAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1299b37199e6SAl Viro goto failed; 1300b37199e6SAl Viro } 13014023bfc9SAl Viro nd->inode = inode; 130231e6b01fSNick Piggin return 0; 1303ef7562d5SAl Viro 1304ef7562d5SAl Viro failed: 1305ef7562d5SAl Viro return -ECHILD; 130631e6b01fSNick Piggin } 130731e6b01fSNick Piggin 13089875cf80SDavid Howells /* 1309cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1310cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1311cc53ce53SDavid Howells * caller is permitted to proceed or not. 1312cc53ce53SDavid Howells */ 13137cc90cc3SAl Viro int follow_down(struct path *path) 1314cc53ce53SDavid Howells { 1315cc53ce53SDavid Howells unsigned managed; 1316cc53ce53SDavid Howells int ret; 1317cc53ce53SDavid Howells 1318cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1319cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1320cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1321cc53ce53SDavid Howells * being held. 1322cc53ce53SDavid Howells * 1323cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1324cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1325cc53ce53SDavid Howells * other than its daemon the right to mount on its 1326cc53ce53SDavid Howells * superstructure. 1327cc53ce53SDavid Howells * 1328cc53ce53SDavid Howells * The filesystem may sleep at this point. 1329cc53ce53SDavid Howells */ 1330cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1331cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1332cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1333ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 13341aed3e42SAl Viro path->dentry, false); 1335cc53ce53SDavid Howells if (ret < 0) 1336cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1337cc53ce53SDavid Howells } 1338cc53ce53SDavid Howells 1339cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1340cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1341cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1342cc53ce53SDavid Howells if (!mounted) 1343cc53ce53SDavid Howells break; 1344cc53ce53SDavid Howells dput(path->dentry); 1345cc53ce53SDavid Howells mntput(path->mnt); 1346cc53ce53SDavid Howells path->mnt = mounted; 1347cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1348cc53ce53SDavid Howells continue; 1349cc53ce53SDavid Howells } 1350cc53ce53SDavid Howells 1351cc53ce53SDavid Howells /* Don't handle automount points here */ 1352cc53ce53SDavid Howells break; 1353cc53ce53SDavid Howells } 1354cc53ce53SDavid Howells return 0; 1355cc53ce53SDavid Howells } 13564d359507SAl Viro EXPORT_SYMBOL(follow_down); 1357cc53ce53SDavid Howells 1358cc53ce53SDavid Howells /* 13599875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 13609875cf80SDavid Howells */ 13619875cf80SDavid Howells static void follow_mount(struct path *path) 13629875cf80SDavid Howells { 13639875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 13649875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 13659875cf80SDavid Howells if (!mounted) 13669875cf80SDavid Howells break; 13679875cf80SDavid Howells dput(path->dentry); 13689875cf80SDavid Howells mntput(path->mnt); 13699875cf80SDavid Howells path->mnt = mounted; 13709875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 13719875cf80SDavid Howells } 13729875cf80SDavid Howells } 13739875cf80SDavid Howells 137431e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 13751da177e4SLinus Torvalds { 13767bd88377SAl Viro if (!nd->root.mnt) 13772a737871SAl Viro set_root(nd); 1378e518ddb7SAndreas Mohr 13791da177e4SLinus Torvalds while(1) { 13804ac91378SJan Blunck struct dentry *old = nd->path.dentry; 13811da177e4SLinus Torvalds 13822a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 13832a737871SAl Viro nd->path.mnt == nd->root.mnt) { 13841da177e4SLinus Torvalds break; 13851da177e4SLinus Torvalds } 13864ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 13873088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 13883088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 13891da177e4SLinus Torvalds dput(old); 13901da177e4SLinus Torvalds break; 13911da177e4SLinus Torvalds } 13923088dd70SAl Viro if (!follow_up(&nd->path)) 13931da177e4SLinus Torvalds break; 13941da177e4SLinus Torvalds } 139579ed0226SAl Viro follow_mount(&nd->path); 139631e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 13971da177e4SLinus Torvalds } 13981da177e4SLinus Torvalds 13991da177e4SLinus Torvalds /* 1400bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1401bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1402bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1403bad61189SMiklos Szeredi * 1404bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1405baa03890SNick Piggin */ 1406bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1407201f956eSAl Viro unsigned int flags, bool *need_lookup) 1408baa03890SNick Piggin { 1409baa03890SNick Piggin struct dentry *dentry; 1410bad61189SMiklos Szeredi int error; 1411baa03890SNick Piggin 1412bad61189SMiklos Szeredi *need_lookup = false; 1413bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1414bad61189SMiklos Szeredi if (dentry) { 141539e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1416201f956eSAl Viro error = d_revalidate(dentry, flags); 1417bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1418bad61189SMiklos Szeredi if (error < 0) { 1419bad61189SMiklos Szeredi dput(dentry); 1420bad61189SMiklos Szeredi return ERR_PTR(error); 14215542aa2fSEric W. Biederman } else { 14225542aa2fSEric W. Biederman d_invalidate(dentry); 1423bad61189SMiklos Szeredi dput(dentry); 1424bad61189SMiklos Szeredi dentry = NULL; 1425bad61189SMiklos Szeredi } 1426bad61189SMiklos Szeredi } 1427bad61189SMiklos Szeredi } 1428bad61189SMiklos Szeredi } 1429baa03890SNick Piggin 1430bad61189SMiklos Szeredi if (!dentry) { 1431bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1432baa03890SNick Piggin if (unlikely(!dentry)) 1433baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1434baa03890SNick Piggin 1435bad61189SMiklos Szeredi *need_lookup = true; 1436baa03890SNick Piggin } 1437baa03890SNick Piggin return dentry; 1438baa03890SNick Piggin } 1439baa03890SNick Piggin 1440baa03890SNick Piggin /* 144113a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 144213a2c3beSJ. Bruce Fields * unhashed. 1443bad61189SMiklos Szeredi * 1444bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 144544396f4bSJosef Bacik */ 1446bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 144772bd866aSAl Viro unsigned int flags) 144844396f4bSJosef Bacik { 144944396f4bSJosef Bacik struct dentry *old; 145044396f4bSJosef Bacik 145144396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1452bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1453e188dc02SMiklos Szeredi dput(dentry); 145444396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1455e188dc02SMiklos Szeredi } 145644396f4bSJosef Bacik 145772bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 145844396f4bSJosef Bacik if (unlikely(old)) { 145944396f4bSJosef Bacik dput(dentry); 146044396f4bSJosef Bacik dentry = old; 146144396f4bSJosef Bacik } 146244396f4bSJosef Bacik return dentry; 146344396f4bSJosef Bacik } 146444396f4bSJosef Bacik 1465a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 146672bd866aSAl Viro struct dentry *base, unsigned int flags) 1467a3255546SAl Viro { 1468bad61189SMiklos Szeredi bool need_lookup; 1469a3255546SAl Viro struct dentry *dentry; 1470a3255546SAl Viro 147172bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1472bad61189SMiklos Szeredi if (!need_lookup) 1473a3255546SAl Viro return dentry; 1474bad61189SMiklos Szeredi 147572bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1476a3255546SAl Viro } 1477a3255546SAl Viro 147844396f4bSJosef Bacik /* 14791da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 14801da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 14811da177e4SLinus Torvalds * It _is_ time-critical. 14821da177e4SLinus Torvalds */ 1483e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 1484254cf582SAl Viro struct path *path, struct inode **inode, 1485254cf582SAl Viro unsigned *seqp) 14861da177e4SLinus Torvalds { 14874ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 148831e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 14895a18fff2SAl Viro int need_reval = 1; 14905a18fff2SAl Viro int status = 1; 14919875cf80SDavid Howells int err; 14929875cf80SDavid Howells 14933cac260aSAl Viro /* 1494b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1495b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1496b04f784eSNick Piggin * do the non-racy lookup, below. 1497b04f784eSNick Piggin */ 149831e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 149931e6b01fSNick Piggin unsigned seq; 1500766c4cbfSAl Viro bool negative; 1501da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15025a18fff2SAl Viro if (!dentry) 15035a18fff2SAl Viro goto unlazy; 15045a18fff2SAl Viro 150512f8ad4bSLinus Torvalds /* 150612f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 150712f8ad4bSLinus Torvalds * the dentry name information from lookup. 150812f8ad4bSLinus Torvalds */ 150963afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1510766c4cbfSAl Viro negative = d_is_negative(dentry); 151112f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 151212f8ad4bSLinus Torvalds return -ECHILD; 1513766c4cbfSAl Viro if (negative) 1514766c4cbfSAl Viro return -ENOENT; 151512f8ad4bSLinus Torvalds 151612f8ad4bSLinus Torvalds /* 151712f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 151812f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 151912f8ad4bSLinus Torvalds * 152012f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 152112f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 152212f8ad4bSLinus Torvalds */ 152331e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 152431e6b01fSNick Piggin return -ECHILD; 15255a18fff2SAl Viro 1526254cf582SAl Viro *seqp = seq; 152724643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 15284ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15295a18fff2SAl Viro if (unlikely(status <= 0)) { 15305a18fff2SAl Viro if (status != -ECHILD) 15315a18fff2SAl Viro need_reval = 0; 15325a18fff2SAl Viro goto unlazy; 15335a18fff2SAl Viro } 153424643087SAl Viro } 153531e6b01fSNick Piggin path->mnt = mnt; 153631e6b01fSNick Piggin path->dentry = dentry; 1537254cf582SAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 15389875cf80SDavid Howells return 0; 15395a18fff2SAl Viro unlazy: 1540254cf582SAl Viro if (unlazy_walk(nd, dentry, seq)) 15415a18fff2SAl Viro return -ECHILD; 15425a18fff2SAl Viro } else { 1543e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 154424643087SAl Viro } 15455a18fff2SAl Viro 154681e6f520SAl Viro if (unlikely(!dentry)) 154781e6f520SAl Viro goto need_lookup; 15485a18fff2SAl Viro 15495a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 15504ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15515a18fff2SAl Viro if (unlikely(status <= 0)) { 15525a18fff2SAl Viro if (status < 0) { 15535a18fff2SAl Viro dput(dentry); 15545a18fff2SAl Viro return status; 15555a18fff2SAl Viro } 15565542aa2fSEric W. Biederman d_invalidate(dentry); 15575a18fff2SAl Viro dput(dentry); 155881e6f520SAl Viro goto need_lookup; 15595a18fff2SAl Viro } 1560697f514dSMiklos Szeredi 1561766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1562766c4cbfSAl Viro dput(dentry); 1563766c4cbfSAl Viro return -ENOENT; 1564766c4cbfSAl Viro } 15651da177e4SLinus Torvalds path->mnt = mnt; 15661da177e4SLinus Torvalds path->dentry = dentry; 1567756daf26SNeilBrown err = follow_managed(path, nd); 15688402752eSAl Viro if (likely(!err)) 156963afdfc7SDavid Howells *inode = d_backing_inode(path->dentry); 15708402752eSAl Viro return err; 157181e6f520SAl Viro 157281e6f520SAl Viro need_lookup: 1573697f514dSMiklos Szeredi return 1; 1574697f514dSMiklos Szeredi } 1575697f514dSMiklos Szeredi 1576697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1577cc2a5271SAl Viro static int lookup_slow(struct nameidata *nd, struct path *path) 1578697f514dSMiklos Szeredi { 1579697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1580697f514dSMiklos Szeredi 1581697f514dSMiklos Szeredi parent = nd->path.dentry; 158281e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 158381e6f520SAl Viro 158481e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 1585cc2a5271SAl Viro dentry = __lookup_hash(&nd->last, parent, nd->flags); 158681e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 158781e6f520SAl Viro if (IS_ERR(dentry)) 158881e6f520SAl Viro return PTR_ERR(dentry); 1589697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1590697f514dSMiklos Szeredi path->dentry = dentry; 15918402752eSAl Viro return follow_managed(path, nd); 15921da177e4SLinus Torvalds } 15931da177e4SLinus Torvalds 159452094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 159552094c8aSAl Viro { 159652094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 15974ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 159852094c8aSAl Viro if (err != -ECHILD) 159952094c8aSAl Viro return err; 16006e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 160152094c8aSAl Viro return -ECHILD; 160252094c8aSAl Viro } 16034ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 160452094c8aSAl Viro } 160552094c8aSAl Viro 16069856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 16079856fa1bSAl Viro { 16089856fa1bSAl Viro if (type == LAST_DOTDOT) { 16099856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 161070291aecSAl Viro return follow_dotdot_rcu(nd); 16119856fa1bSAl Viro } else 16129856fa1bSAl Viro follow_dotdot(nd); 16139856fa1bSAl Viro } 16149856fa1bSAl Viro return 0; 16159856fa1bSAl Viro } 16169856fa1bSAl Viro 1617181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1618181548c0SAl Viro struct inode *inode, unsigned seq) 1619d63ff28fSAl Viro { 1620626de996SAl Viro int error; 16211cf2665bSAl Viro struct saved *last; 1622756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1623626de996SAl Viro path_to_nameidata(link, nd); 1624626de996SAl Viro return -ELOOP; 1625626de996SAl Viro } 1626d63ff28fSAl Viro if (nd->flags & LOOKUP_RCU) { 16277973387aSAl Viro if (unlikely(unlazy_link(nd, link, seq))) 1628d63ff28fSAl Viro return -ECHILD; 16297973387aSAl Viro } else { 1630cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1631cd179f44SAl Viro mntget(link->mnt); 16327973387aSAl Viro } 1633626de996SAl Viro error = nd_alloc_stack(nd); 1634626de996SAl Viro if (unlikely(error)) { 1635cd179f44SAl Viro path_put(link); 1636626de996SAl Viro return error; 1637626de996SAl Viro } 1638626de996SAl Viro 1639ab104923SAl Viro last = nd->stack + nd->depth++; 16401cf2665bSAl Viro last->link = *link; 1641ab104923SAl Viro last->cookie = NULL; 1642181548c0SAl Viro last->inode = inode; 16430450b2d1SAl Viro last->seq = seq; 1644d63ff28fSAl Viro return 1; 1645d63ff28fSAl Viro } 1646d63ff28fSAl Viro 16473ddcd056SLinus Torvalds /* 16483ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 16493ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 16503ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 16513ddcd056SLinus Torvalds * for the common case. 16523ddcd056SLinus Torvalds */ 1653254cf582SAl Viro static inline int should_follow_link(struct nameidata *nd, struct path *link, 1654181548c0SAl Viro int follow, 1655181548c0SAl Viro struct inode *inode, unsigned seq) 16563ddcd056SLinus Torvalds { 1657d63ff28fSAl Viro if (likely(!d_is_symlink(link->dentry))) 1658d63ff28fSAl Viro return 0; 1659d63ff28fSAl Viro if (!follow) 1660d63ff28fSAl Viro return 0; 1661181548c0SAl Viro return pick_link(nd, link, inode, seq); 16623ddcd056SLinus Torvalds } 16633ddcd056SLinus Torvalds 16644693a547SAl Viro enum {WALK_GET = 1, WALK_PUT = 2}; 16654693a547SAl Viro 16664693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1667ce57dfc1SAl Viro { 1668caa85634SAl Viro struct path path; 1669ce57dfc1SAl Viro struct inode *inode; 1670254cf582SAl Viro unsigned seq; 1671ce57dfc1SAl Viro int err; 1672ce57dfc1SAl Viro /* 1673ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1674ce57dfc1SAl Viro * to be able to know about the current root directory and 1675ce57dfc1SAl Viro * parent relationships. 1676ce57dfc1SAl Viro */ 16774693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 16784693a547SAl Viro err = handle_dots(nd, nd->last_type); 16794693a547SAl Viro if (flags & WALK_PUT) 16804693a547SAl Viro put_link(nd); 16814693a547SAl Viro return err; 16824693a547SAl Viro } 1683254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1684ce57dfc1SAl Viro if (unlikely(err)) { 1685697f514dSMiklos Szeredi if (err < 0) 1686f0a9ba70SAl Viro return err; 1687697f514dSMiklos Szeredi 1688caa85634SAl Viro err = lookup_slow(nd, &path); 1689697f514dSMiklos Szeredi if (err < 0) 1690f0a9ba70SAl Viro return err; 1691697f514dSMiklos Szeredi 169263afdfc7SDavid Howells inode = d_backing_inode(path.dentry); 1693254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1694697f514dSMiklos Szeredi err = -ENOENT; 1695caa85634SAl Viro if (d_is_negative(path.dentry)) 1696697f514dSMiklos Szeredi goto out_path_put; 1697766c4cbfSAl Viro } 1698697f514dSMiklos Szeredi 16994693a547SAl Viro if (flags & WALK_PUT) 17004693a547SAl Viro put_link(nd); 1701181548c0SAl Viro err = should_follow_link(nd, &path, flags & WALK_GET, inode, seq); 1702d63ff28fSAl Viro if (unlikely(err)) 1703d63ff28fSAl Viro return err; 1704caa85634SAl Viro path_to_nameidata(&path, nd); 1705ce57dfc1SAl Viro nd->inode = inode; 1706254cf582SAl Viro nd->seq = seq; 1707ce57dfc1SAl Viro return 0; 1708697f514dSMiklos Szeredi 1709697f514dSMiklos Szeredi out_path_put: 1710caa85634SAl Viro path_to_nameidata(&path, nd); 1711697f514dSMiklos Szeredi return err; 1712ce57dfc1SAl Viro } 1713ce57dfc1SAl Viro 17141da177e4SLinus Torvalds /* 1715bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1716bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1717bfcfaa77SLinus Torvalds * 1718bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1719bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1720bfcfaa77SLinus Torvalds * fast. 1721bfcfaa77SLinus Torvalds * 1722bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1723bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1724bfcfaa77SLinus Torvalds * crossing operation. 1725bfcfaa77SLinus Torvalds * 1726bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1727bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1728bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1729bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1730bfcfaa77SLinus Torvalds */ 1731bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1732bfcfaa77SLinus Torvalds 1733f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1734bfcfaa77SLinus Torvalds 1735f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1736bfcfaa77SLinus Torvalds 1737bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1738bfcfaa77SLinus Torvalds { 173999d263d4SLinus Torvalds return hash_64(hash, 32); 1740bfcfaa77SLinus Torvalds } 1741bfcfaa77SLinus Torvalds 1742bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1743bfcfaa77SLinus Torvalds 1744bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1745bfcfaa77SLinus Torvalds 1746bfcfaa77SLinus Torvalds #endif 1747bfcfaa77SLinus Torvalds 1748bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1749bfcfaa77SLinus Torvalds { 1750bfcfaa77SLinus Torvalds unsigned long a, mask; 1751bfcfaa77SLinus Torvalds unsigned long hash = 0; 1752bfcfaa77SLinus Torvalds 1753bfcfaa77SLinus Torvalds for (;;) { 1754e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1755bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1756bfcfaa77SLinus Torvalds break; 1757bfcfaa77SLinus Torvalds hash += a; 1758f132c5beSAl Viro hash *= 9; 1759bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1760bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1761bfcfaa77SLinus Torvalds if (!len) 1762bfcfaa77SLinus Torvalds goto done; 1763bfcfaa77SLinus Torvalds } 1764a5c21dceSWill Deacon mask = bytemask_from_count(len); 1765bfcfaa77SLinus Torvalds hash += mask & a; 1766bfcfaa77SLinus Torvalds done: 1767bfcfaa77SLinus Torvalds return fold_hash(hash); 1768bfcfaa77SLinus Torvalds } 1769bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1770bfcfaa77SLinus Torvalds 1771bfcfaa77SLinus Torvalds /* 1772bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1773d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1774bfcfaa77SLinus Torvalds */ 1775d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1776bfcfaa77SLinus Torvalds { 177736126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 177836126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1779bfcfaa77SLinus Torvalds 1780bfcfaa77SLinus Torvalds hash = a = 0; 1781bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1782bfcfaa77SLinus Torvalds do { 1783bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1784bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1785e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 178636126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 178736126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1788bfcfaa77SLinus Torvalds 178936126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 179036126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 179136126f8fSLinus Torvalds 179236126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 179336126f8fSLinus Torvalds 179436126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 17959226b5b4SLinus Torvalds len += find_zero(mask); 1796d6bb3e90SLinus Torvalds return hashlen_create(fold_hash(hash), len); 1797bfcfaa77SLinus Torvalds } 1798bfcfaa77SLinus Torvalds 1799bfcfaa77SLinus Torvalds #else 1800bfcfaa77SLinus Torvalds 18010145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 18020145acc2SLinus Torvalds { 18030145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 18040145acc2SLinus Torvalds while (len--) 18050145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 18060145acc2SLinus Torvalds return end_name_hash(hash); 18070145acc2SLinus Torvalds } 1808ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 18090145acc2SLinus Torvalds 18103ddcd056SLinus Torvalds /* 1811200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1812200e9ef7SLinus Torvalds * one character. 1813200e9ef7SLinus Torvalds */ 1814d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1815200e9ef7SLinus Torvalds { 1816200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1817200e9ef7SLinus Torvalds unsigned long len = 0, c; 1818200e9ef7SLinus Torvalds 1819200e9ef7SLinus Torvalds c = (unsigned char)*name; 1820200e9ef7SLinus Torvalds do { 1821200e9ef7SLinus Torvalds len++; 1822200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1823200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1824200e9ef7SLinus Torvalds } while (c && c != '/'); 1825d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 1826200e9ef7SLinus Torvalds } 1827200e9ef7SLinus Torvalds 1828bfcfaa77SLinus Torvalds #endif 1829bfcfaa77SLinus Torvalds 1830200e9ef7SLinus Torvalds /* 18311da177e4SLinus Torvalds * Name resolution. 1832ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1833ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 18341da177e4SLinus Torvalds * 1835ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1836ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 18371da177e4SLinus Torvalds */ 18386de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 18391da177e4SLinus Torvalds { 18401da177e4SLinus Torvalds int err; 18411da177e4SLinus Torvalds 18421da177e4SLinus Torvalds while (*name=='/') 18431da177e4SLinus Torvalds name++; 18441da177e4SLinus Torvalds if (!*name) 18459e18f10aSAl Viro return 0; 18461da177e4SLinus Torvalds 18471da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 18481da177e4SLinus Torvalds for(;;) { 1849d6bb3e90SLinus Torvalds u64 hash_len; 1850fe479a58SAl Viro int type; 18511da177e4SLinus Torvalds 185252094c8aSAl Viro err = may_lookup(nd); 18531da177e4SLinus Torvalds if (err) 18543595e234SAl Viro return err; 18551da177e4SLinus Torvalds 1856d6bb3e90SLinus Torvalds hash_len = hash_name(name); 18571da177e4SLinus Torvalds 1858fe479a58SAl Viro type = LAST_NORM; 1859d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 1860fe479a58SAl Viro case 2: 1861200e9ef7SLinus Torvalds if (name[1] == '.') { 1862fe479a58SAl Viro type = LAST_DOTDOT; 186316c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 186416c2cd71SAl Viro } 1865fe479a58SAl Viro break; 1866fe479a58SAl Viro case 1: 1867fe479a58SAl Viro type = LAST_DOT; 1868fe479a58SAl Viro } 18695a202bcdSAl Viro if (likely(type == LAST_NORM)) { 18705a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 187116c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 18725a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 1873a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 1874da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 18755a202bcdSAl Viro if (err < 0) 18763595e234SAl Viro return err; 1877d6bb3e90SLinus Torvalds hash_len = this.hash_len; 1878d6bb3e90SLinus Torvalds name = this.name; 18795a202bcdSAl Viro } 18805a202bcdSAl Viro } 1881fe479a58SAl Viro 1882d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 1883d6bb3e90SLinus Torvalds nd->last.name = name; 18845f4a6a69SAl Viro nd->last_type = type; 18855f4a6a69SAl Viro 1886d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 1887d6bb3e90SLinus Torvalds if (!*name) 1888bdf6cbf1SAl Viro goto OK; 1889200e9ef7SLinus Torvalds /* 1890200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1891200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1892200e9ef7SLinus Torvalds */ 1893200e9ef7SLinus Torvalds do { 1894d6bb3e90SLinus Torvalds name++; 1895d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 18968620c238SAl Viro if (unlikely(!*name)) { 18978620c238SAl Viro OK: 1898368ee9baSAl Viro /* pathname body, done */ 18998620c238SAl Viro if (!nd->depth) 19008620c238SAl Viro return 0; 19018620c238SAl Viro name = nd->stack[nd->depth - 1].name; 1902368ee9baSAl Viro /* trailing symlink, done */ 19038620c238SAl Viro if (!name) 19048620c238SAl Viro return 0; 19058620c238SAl Viro /* last component of nested symlink */ 19064693a547SAl Viro err = walk_component(nd, WALK_GET | WALK_PUT); 19078620c238SAl Viro } else { 19084693a547SAl Viro err = walk_component(nd, WALK_GET); 19098620c238SAl Viro } 1910ce57dfc1SAl Viro if (err < 0) 19113595e234SAl Viro return err; 1912fe479a58SAl Viro 1913ce57dfc1SAl Viro if (err) { 1914626de996SAl Viro const char *s = get_link(nd); 19155a460275SAl Viro 19163595e234SAl Viro if (unlikely(IS_ERR(s))) 19173595e234SAl Viro return PTR_ERR(s); 1918172a39a0SAl Viro err = 0; 191912b09578SAl Viro if (unlikely(!s)) { 192012b09578SAl Viro /* jumped */ 1921b9ff4429SAl Viro put_link(nd); 192212b09578SAl Viro } else { 1923071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 192432cd7468SAl Viro name = s; 19259e18f10aSAl Viro continue; 192648c8b0c5SAl Viro } 192731e6b01fSNick Piggin } 19283595e234SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) 19293595e234SAl Viro return -ENOTDIR; 19305f4a6a69SAl Viro } 1931ce57dfc1SAl Viro } 19321da177e4SLinus Torvalds 1933368ee9baSAl Viro static const char *path_init(int dfd, const struct filename *name, 1934368ee9baSAl Viro unsigned int flags, struct nameidata *nd) 193531e6b01fSNick Piggin { 193631e6b01fSNick Piggin int retval = 0; 1937fd2f7cb5SAl Viro const char *s = name->name; 193831e6b01fSNick Piggin 193931e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 1940980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 194131e6b01fSNick Piggin nd->depth = 0; 1942368ee9baSAl Viro nd->total_link_count = 0; 19435b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 1944b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 1945b18825a7SDavid Howells struct inode *inode = root->d_inode; 1946fd2f7cb5SAl Viro if (*s) { 194744b1d530SMiklos Szeredi if (!d_can_lookup(root)) 1948368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 19495b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 19505b6ca027SAl Viro if (retval) 1951368ee9baSAl Viro return ERR_PTR(retval); 195273d049a4SAl Viro } 19535b6ca027SAl Viro nd->path = nd->root; 19545b6ca027SAl Viro nd->inode = inode; 19555b6ca027SAl Viro if (flags & LOOKUP_RCU) { 19568b61e74fSAl Viro rcu_read_lock(); 19575b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 195848a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 19595b6ca027SAl Viro } else { 19605b6ca027SAl Viro path_get(&nd->path); 19615b6ca027SAl Viro } 1962368ee9baSAl Viro return s; 19635b6ca027SAl Viro } 19645b6ca027SAl Viro 196531e6b01fSNick Piggin nd->root.mnt = NULL; 196631e6b01fSNick Piggin 196748a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 1968fd2f7cb5SAl Viro if (*s == '/') { 1969e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 19708b61e74fSAl Viro rcu_read_lock(); 19717bd88377SAl Viro nd->seq = set_root_rcu(nd); 1972e41f7d4eSAl Viro } else { 1973e41f7d4eSAl Viro set_root(nd); 1974e41f7d4eSAl Viro path_get(&nd->root); 1975e41f7d4eSAl Viro } 197631e6b01fSNick Piggin nd->path = nd->root; 197731e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1978e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 197931e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1980c28cc364SNick Piggin unsigned seq; 198131e6b01fSNick Piggin 19828b61e74fSAl Viro rcu_read_lock(); 198331e6b01fSNick Piggin 1984c28cc364SNick Piggin do { 1985c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 198631e6b01fSNick Piggin nd->path = fs->pwd; 1987c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1988c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1989e41f7d4eSAl Viro } else { 1990e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1991e41f7d4eSAl Viro } 199231e6b01fSNick Piggin } else { 1993582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 19942903ff01SAl Viro struct fd f = fdget_raw(dfd); 199531e6b01fSNick Piggin struct dentry *dentry; 199631e6b01fSNick Piggin 19972903ff01SAl Viro if (!f.file) 1998368ee9baSAl Viro return ERR_PTR(-EBADF); 199931e6b01fSNick Piggin 20002903ff01SAl Viro dentry = f.file->f_path.dentry; 200131e6b01fSNick Piggin 2002fd2f7cb5SAl Viro if (*s) { 200344b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 20042903ff01SAl Viro fdput(f); 2005368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2006f52e0c11SAl Viro } 20072903ff01SAl Viro } 20082903ff01SAl Viro 20092903ff01SAl Viro nd->path = f.file->f_path; 2010e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 20118b61e74fSAl Viro rcu_read_lock(); 201234a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 201334a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 20145590ff0dSUlrich Drepper } else { 20152903ff01SAl Viro path_get(&nd->path); 201634a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 20171da177e4SLinus Torvalds } 201834a26b99SAl Viro fdput(f); 2019368ee9baSAl Viro return s; 2020e41f7d4eSAl Viro } 2021e41f7d4eSAl Viro 202231e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 20234023bfc9SAl Viro if (!(flags & LOOKUP_RCU)) 2024368ee9baSAl Viro return s; 20254023bfc9SAl Viro if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) 2026368ee9baSAl Viro return s; 20274023bfc9SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 20284023bfc9SAl Viro nd->root.mnt = NULL; 20294023bfc9SAl Viro rcu_read_unlock(); 2030368ee9baSAl Viro return ERR_PTR(-ECHILD); 20319b4a9b14SAl Viro } 20329b4a9b14SAl Viro 2033893b7775SAl Viro static void path_cleanup(struct nameidata *nd) 2034893b7775SAl Viro { 2035893b7775SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 2036893b7775SAl Viro path_put(&nd->root); 2037893b7775SAl Viro nd->root.mnt = NULL; 2038893b7775SAl Viro } 20399b4a9b14SAl Viro } 20409b4a9b14SAl Viro 20413bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 204295fa25d9SAl Viro { 204395fa25d9SAl Viro const char *s; 2044fec2fa24SAl Viro int error = may_follow_link(nd); 2045deb106c6SAl Viro if (unlikely(error)) 20463bdba28bSAl Viro return ERR_PTR(error); 204795fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2048fab51e8aSAl Viro nd->stack[0].name = NULL; 20493b2e7f75SAl Viro s = get_link(nd); 2050deb106c6SAl Viro return s ? s : ""; 205195fa25d9SAl Viro } 205295fa25d9SAl Viro 2053caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2054bd92d7feSAl Viro { 2055bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2056bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2057bd92d7feSAl Viro 2058bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 2059deb106c6SAl Viro return walk_component(nd, 20604693a547SAl Viro nd->flags & LOOKUP_FOLLOW 20614693a547SAl Viro ? nd->depth 20624693a547SAl Viro ? WALK_PUT | WALK_GET 20634693a547SAl Viro : WALK_GET 20644693a547SAl Viro : 0); 2065bd92d7feSAl Viro } 2066bd92d7feSAl Viro 20679b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 20685eb6b495SAl Viro static int path_lookupat(int dfd, const struct filename *name, 20699b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 20709b4a9b14SAl Viro { 2071368ee9baSAl Viro const char *s = path_init(dfd, name, flags, nd); 2072bd92d7feSAl Viro int err; 207331e6b01fSNick Piggin 2074368ee9baSAl Viro if (IS_ERR(s)) 2075368ee9baSAl Viro return PTR_ERR(s); 20763bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 20773bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 20783bdba28bSAl Viro s = trailing_symlink(nd); 20793bdba28bSAl Viro if (IS_ERR(s)) { 20803bdba28bSAl Viro err = PTR_ERR(s); 20816d7b5aaeSAl Viro break; 2082bd92d7feSAl Viro } 2083bd92d7feSAl Viro } 20849f1fafeeSAl Viro if (!err) 20859f1fafeeSAl Viro err = complete_walk(nd); 2086bd92d7feSAl Viro 2087deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2088deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2089bd23a539SAl Viro err = -ENOTDIR; 2090deb106c6SAl Viro if (err) 2091deb106c6SAl Viro terminate_walk(nd); 209216c2cd71SAl Viro 2093893b7775SAl Viro path_cleanup(nd); 2094bd92d7feSAl Viro return err; 209531e6b01fSNick Piggin } 209631e6b01fSNick Piggin 2097873f1eedSJeff Layton static int filename_lookup(int dfd, struct filename *name, 2098873f1eedSJeff Layton unsigned int flags, struct nameidata *nd) 2099873f1eedSJeff Layton { 2100894bc8c4SAl Viro int retval; 2101756daf26SNeilBrown struct nameidata *saved_nd = set_nameidata(nd); 2102894bc8c4SAl Viro 2103894bc8c4SAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 2104873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 21055eb6b495SAl Viro retval = path_lookupat(dfd, name, flags, nd); 2106873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 21075eb6b495SAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 2108873f1eedSJeff Layton 2109873f1eedSJeff Layton if (likely(!retval)) 2110adb5c247SJeff Layton audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); 2111756daf26SNeilBrown restore_nameidata(saved_nd); 2112873f1eedSJeff Layton return retval; 2113873f1eedSJeff Layton } 2114873f1eedSJeff Layton 21158bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 21168bcb77faSAl Viro static int path_parentat(int dfd, const struct filename *name, 21178bcb77faSAl Viro unsigned int flags, struct nameidata *nd) 21188bcb77faSAl Viro { 2119368ee9baSAl Viro const char *s = path_init(dfd, name, flags, nd); 2120368ee9baSAl Viro int err; 2121368ee9baSAl Viro if (IS_ERR(s)) 2122368ee9baSAl Viro return PTR_ERR(s); 2123368ee9baSAl Viro err = link_path_walk(s, nd); 21248bcb77faSAl Viro if (!err) 21258bcb77faSAl Viro err = complete_walk(nd); 2126deb106c6SAl Viro if (err) 2127deb106c6SAl Viro terminate_walk(nd); 21288bcb77faSAl Viro path_cleanup(nd); 21298bcb77faSAl Viro return err; 21308bcb77faSAl Viro } 21318bcb77faSAl Viro 21328bcb77faSAl Viro static int filename_parentat(int dfd, struct filename *name, 21338bcb77faSAl Viro unsigned int flags, struct nameidata *nd) 21348bcb77faSAl Viro { 21358bcb77faSAl Viro int retval; 21368bcb77faSAl Viro struct nameidata *saved_nd = set_nameidata(nd); 21378bcb77faSAl Viro 21388bcb77faSAl Viro retval = path_parentat(dfd, name, flags | LOOKUP_RCU, nd); 21398bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 21408bcb77faSAl Viro retval = path_parentat(dfd, name, flags, nd); 21418bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 21428bcb77faSAl Viro retval = path_parentat(dfd, name, flags | LOOKUP_REVAL, nd); 21438bcb77faSAl Viro 21448bcb77faSAl Viro if (likely(!retval)) 21458bcb77faSAl Viro audit_inode(name, nd->path.dentry, LOOKUP_PARENT); 21468bcb77faSAl Viro restore_nameidata(saved_nd); 21478bcb77faSAl Viro return retval; 21488bcb77faSAl Viro } 21498bcb77faSAl Viro 215079714f72SAl Viro /* does lookup, returns the object with parent locked */ 215179714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 21525590ff0dSUlrich Drepper { 215351689104SPaul Moore struct filename *filename = getname_kernel(name); 215479714f72SAl Viro struct nameidata nd; 215579714f72SAl Viro struct dentry *d; 215651689104SPaul Moore int err; 215751689104SPaul Moore 215851689104SPaul Moore if (IS_ERR(filename)) 215951689104SPaul Moore return ERR_CAST(filename); 216051689104SPaul Moore 21618bcb77faSAl Viro err = filename_parentat(AT_FDCWD, filename, 0, &nd); 216251689104SPaul Moore if (err) { 216351689104SPaul Moore d = ERR_PTR(err); 216451689104SPaul Moore goto out; 216551689104SPaul Moore } 216679714f72SAl Viro if (nd.last_type != LAST_NORM) { 216779714f72SAl Viro path_put(&nd.path); 216851689104SPaul Moore d = ERR_PTR(-EINVAL); 216951689104SPaul Moore goto out; 217079714f72SAl Viro } 217179714f72SAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 21721e0ea001SAl Viro d = __lookup_hash(&nd.last, nd.path.dentry, 0); 217379714f72SAl Viro if (IS_ERR(d)) { 217479714f72SAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 217579714f72SAl Viro path_put(&nd.path); 217651689104SPaul Moore goto out; 217779714f72SAl Viro } 217879714f72SAl Viro *path = nd.path; 217951689104SPaul Moore out: 218051689104SPaul Moore putname(filename); 218179714f72SAl Viro return d; 21825590ff0dSUlrich Drepper } 21835590ff0dSUlrich Drepper 2184d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2185d1811465SAl Viro { 2186d1811465SAl Viro struct nameidata nd; 218774eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 218874eb8cc5SAl Viro int res = PTR_ERR(filename); 218974eb8cc5SAl Viro 219074eb8cc5SAl Viro if (!IS_ERR(filename)) { 219174eb8cc5SAl Viro res = filename_lookup(AT_FDCWD, filename, flags, &nd); 219274eb8cc5SAl Viro putname(filename); 2193d1811465SAl Viro if (!res) 2194d1811465SAl Viro *path = nd.path; 219574eb8cc5SAl Viro } 2196d1811465SAl Viro return res; 2197d1811465SAl Viro } 21984d359507SAl Viro EXPORT_SYMBOL(kern_path); 2199d1811465SAl Viro 220016f18200SJosef 'Jeff' Sipek /** 220116f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 220216f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 220316f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 220416f18200SJosef 'Jeff' Sipek * @name: pointer to file name 220516f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2206e0a01249SAl Viro * @path: pointer to struct path to fill 220716f18200SJosef 'Jeff' Sipek */ 220816f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 220916f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2210e0a01249SAl Viro struct path *path) 221116f18200SJosef 'Jeff' Sipek { 221274eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 221374eb8cc5SAl Viro int err = PTR_ERR(filename); 221474eb8cc5SAl Viro 221574eb8cc5SAl Viro BUG_ON(flags & LOOKUP_PARENT); 221674eb8cc5SAl Viro 221774eb8cc5SAl Viro /* the first argument of filename_lookup() is ignored with LOOKUP_ROOT */ 221874eb8cc5SAl Viro if (!IS_ERR(filename)) { 2219e0a01249SAl Viro struct nameidata nd; 2220e0a01249SAl Viro nd.root.dentry = dentry; 2221e0a01249SAl Viro nd.root.mnt = mnt; 222274eb8cc5SAl Viro err = filename_lookup(AT_FDCWD, filename, 222374eb8cc5SAl Viro flags | LOOKUP_ROOT, &nd); 2224e0a01249SAl Viro if (!err) 2225e0a01249SAl Viro *path = nd.path; 222674eb8cc5SAl Viro putname(filename); 222774eb8cc5SAl Viro } 2228e0a01249SAl Viro return err; 222916f18200SJosef 'Jeff' Sipek } 22304d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 223116f18200SJosef 'Jeff' Sipek 2232eead1911SChristoph Hellwig /** 2233a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2234eead1911SChristoph Hellwig * @name: pathname component to lookup 2235eead1911SChristoph Hellwig * @base: base directory to lookup from 2236eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2237eead1911SChristoph Hellwig * 2238a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 22399e7543e9SAl Viro * not be called by generic code. 2240eead1911SChristoph Hellwig */ 2241057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2242057f6c01SJames Morris { 2243057f6c01SJames Morris struct qstr this; 22446a96ba54SAl Viro unsigned int c; 2245cda309deSMiklos Szeredi int err; 2246057f6c01SJames Morris 22472f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 22482f9092e1SDavid Woodhouse 22496a96ba54SAl Viro this.name = name; 22506a96ba54SAl Viro this.len = len; 22510145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 22526a96ba54SAl Viro if (!len) 22536a96ba54SAl Viro return ERR_PTR(-EACCES); 22546a96ba54SAl Viro 225521d8a15aSAl Viro if (unlikely(name[0] == '.')) { 225621d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 225721d8a15aSAl Viro return ERR_PTR(-EACCES); 225821d8a15aSAl Viro } 225921d8a15aSAl Viro 22606a96ba54SAl Viro while (len--) { 22616a96ba54SAl Viro c = *(const unsigned char *)name++; 22626a96ba54SAl Viro if (c == '/' || c == '\0') 22636a96ba54SAl Viro return ERR_PTR(-EACCES); 22646a96ba54SAl Viro } 22655a202bcdSAl Viro /* 22665a202bcdSAl Viro * See if the low-level filesystem might want 22675a202bcdSAl Viro * to use its own hash.. 22685a202bcdSAl Viro */ 22695a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2270da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 22715a202bcdSAl Viro if (err < 0) 22725a202bcdSAl Viro return ERR_PTR(err); 22735a202bcdSAl Viro } 2274eead1911SChristoph Hellwig 2275cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2276cda309deSMiklos Szeredi if (err) 2277cda309deSMiklos Szeredi return ERR_PTR(err); 2278cda309deSMiklos Szeredi 227972bd866aSAl Viro return __lookup_hash(&this, base, 0); 2280057f6c01SJames Morris } 22814d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2282057f6c01SJames Morris 22831fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 22841fa1e7f6SAndy Whitcroft struct path *path, int *empty) 22851da177e4SLinus Torvalds { 22862d8f3038SAl Viro struct nameidata nd; 228791a27b2aSJeff Layton struct filename *tmp = getname_flags(name, flags, empty); 22881da177e4SLinus Torvalds int err = PTR_ERR(tmp); 22891da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 22902d8f3038SAl Viro 22912d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 22922d8f3038SAl Viro 2293873f1eedSJeff Layton err = filename_lookup(dfd, tmp, flags, &nd); 22941da177e4SLinus Torvalds putname(tmp); 22952d8f3038SAl Viro if (!err) 22962d8f3038SAl Viro *path = nd.path; 22971da177e4SLinus Torvalds } 22981da177e4SLinus Torvalds return err; 22991da177e4SLinus Torvalds } 23001da177e4SLinus Torvalds 23011fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 23021fa1e7f6SAndy Whitcroft struct path *path) 23031fa1e7f6SAndy Whitcroft { 2304f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 23051fa1e7f6SAndy Whitcroft } 23064d359507SAl Viro EXPORT_SYMBOL(user_path_at); 23071fa1e7f6SAndy Whitcroft 2308873f1eedSJeff Layton /* 2309873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2310873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2311873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2312873f1eedSJeff Layton * path-walking is complete. 2313873f1eedSJeff Layton */ 231491a27b2aSJeff Layton static struct filename * 2315f5beed75SAl Viro user_path_parent(int dfd, const char __user *path, 2316f5beed75SAl Viro struct path *parent, 2317f5beed75SAl Viro struct qstr *last, 2318f5beed75SAl Viro int *type, 23199e790bd6SJeff Layton unsigned int flags) 23202ad94ae6SAl Viro { 2321f5beed75SAl Viro struct nameidata nd; 232291a27b2aSJeff Layton struct filename *s = getname(path); 23232ad94ae6SAl Viro int error; 23242ad94ae6SAl Viro 23259e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 23269e790bd6SJeff Layton flags &= LOOKUP_REVAL; 23279e790bd6SJeff Layton 23282ad94ae6SAl Viro if (IS_ERR(s)) 232991a27b2aSJeff Layton return s; 23302ad94ae6SAl Viro 23318bcb77faSAl Viro error = filename_parentat(dfd, s, flags, &nd); 233291a27b2aSJeff Layton if (error) { 23332ad94ae6SAl Viro putname(s); 233491a27b2aSJeff Layton return ERR_PTR(error); 233591a27b2aSJeff Layton } 2336f5beed75SAl Viro *parent = nd.path; 2337f5beed75SAl Viro *last = nd.last; 2338f5beed75SAl Viro *type = nd.last_type; 23392ad94ae6SAl Viro 234091a27b2aSJeff Layton return s; 23412ad94ae6SAl Viro } 23422ad94ae6SAl Viro 23438033426eSJeff Layton /** 2344197df04cSAl Viro * mountpoint_last - look up last component for umount 23458033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 23468033426eSJeff Layton * @path: pointer to container for result 23478033426eSJeff Layton * 23488033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 23498033426eSJeff Layton * need to resolve the path without doing any revalidation. 23508033426eSJeff Layton * 23518033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 23528033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 23538033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 23548033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 23558033426eSJeff Layton * bogus and it doesn't exist. 23568033426eSJeff Layton * 23578033426eSJeff Layton * Returns: 23588033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 23598033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 23608033426eSJeff Layton * put in this case. 23618033426eSJeff Layton * 23628033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 23638033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 23648033426eSJeff Layton * The nd->path reference will also be put. 23658033426eSJeff Layton * 23668033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 23678033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 23688033426eSJeff Layton * to the link, and nd->path will *not* be put. 23698033426eSJeff Layton */ 23708033426eSJeff Layton static int 2371197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 23728033426eSJeff Layton { 23738033426eSJeff Layton int error = 0; 23748033426eSJeff Layton struct dentry *dentry; 23758033426eSJeff Layton struct dentry *dir = nd->path.dentry; 23768033426eSJeff Layton 237735759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 237835759521SAl Viro if (nd->flags & LOOKUP_RCU) { 23796e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 2380deb106c6SAl Viro return -ECHILD; 23818033426eSJeff Layton } 23828033426eSJeff Layton 23838033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 23848033426eSJeff Layton 23858033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 23868033426eSJeff Layton error = handle_dots(nd, nd->last_type); 238735759521SAl Viro if (error) 2388deb106c6SAl Viro return error; 23898033426eSJeff Layton dentry = dget(nd->path.dentry); 239035759521SAl Viro goto done; 23918033426eSJeff Layton } 23928033426eSJeff Layton 23938033426eSJeff Layton mutex_lock(&dir->d_inode->i_mutex); 23948033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 23958033426eSJeff Layton if (!dentry) { 23968033426eSJeff Layton /* 23978033426eSJeff Layton * No cached dentry. Mounted dentries are pinned in the cache, 23988033426eSJeff Layton * so that means that this dentry is probably a symlink or the 23998033426eSJeff Layton * path doesn't actually point to a mounted dentry. 24008033426eSJeff Layton */ 24018033426eSJeff Layton dentry = d_alloc(dir, &nd->last); 24028033426eSJeff Layton if (!dentry) { 2403bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 2404deb106c6SAl Viro return -ENOMEM; 24058033426eSJeff Layton } 240635759521SAl Viro dentry = lookup_real(dir->d_inode, dentry, nd->flags); 2407bcceeebaSDave Jones if (IS_ERR(dentry)) { 2408bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 2409deb106c6SAl Viro return PTR_ERR(dentry); 24108033426eSJeff Layton } 2411bcceeebaSDave Jones } 24128033426eSJeff Layton mutex_unlock(&dir->d_inode->i_mutex); 24138033426eSJeff Layton 241435759521SAl Viro done: 2415698934dfSDavid Howells if (d_is_negative(dentry)) { 24168033426eSJeff Layton dput(dentry); 2417deb106c6SAl Viro return -ENOENT; 241835759521SAl Viro } 2419191d7f73SAl Viro if (nd->depth) 2420191d7f73SAl Viro put_link(nd); 24218033426eSJeff Layton path->dentry = dentry; 2422295dc39dSVasily Averin path->mnt = nd->path.mnt; 2423181548c0SAl Viro error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW, 2424181548c0SAl Viro d_backing_inode(dentry), 0); 2425deb106c6SAl Viro if (unlikely(error)) 2426d63ff28fSAl Viro return error; 2427295dc39dSVasily Averin mntget(path->mnt); 24288033426eSJeff Layton follow_mount(path); 2429deb106c6SAl Viro return 0; 24308033426eSJeff Layton } 24318033426eSJeff Layton 24328033426eSJeff Layton /** 2433197df04cSAl Viro * path_mountpoint - look up a path to be umounted 24348033426eSJeff Layton * @dfd: directory file descriptor to start walk from 24358033426eSJeff Layton * @name: full pathname to walk 2436606d6fe3SRandy Dunlap * @path: pointer to container for result 24378033426eSJeff Layton * @flags: lookup flags 24388033426eSJeff Layton * 24398033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2440606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 24418033426eSJeff Layton */ 24428033426eSJeff Layton static int 2443668696dcSAl Viro path_mountpoint(int dfd, const struct filename *name, struct path *path, 244446afd6f6SAl Viro struct nameidata *nd, unsigned int flags) 24458033426eSJeff Layton { 2446368ee9baSAl Viro const char *s = path_init(dfd, name, flags, nd); 2447368ee9baSAl Viro int err; 2448368ee9baSAl Viro if (IS_ERR(s)) 2449368ee9baSAl Viro return PTR_ERR(s); 24503bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 24513bdba28bSAl Viro (err = mountpoint_last(nd, path)) > 0) { 24523bdba28bSAl Viro s = trailing_symlink(nd); 24533bdba28bSAl Viro if (IS_ERR(s)) { 24543bdba28bSAl Viro err = PTR_ERR(s); 24558033426eSJeff Layton break; 24568033426eSJeff Layton } 24573bdba28bSAl Viro } 2458deb106c6SAl Viro terminate_walk(nd); 245946afd6f6SAl Viro path_cleanup(nd); 24608033426eSJeff Layton return err; 24618033426eSJeff Layton } 24628033426eSJeff Layton 24632d864651SAl Viro static int 2464668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 24652d864651SAl Viro unsigned int flags) 24662d864651SAl Viro { 2467756daf26SNeilBrown struct nameidata nd, *saved; 2468cbaab2dbSAl Viro int error; 2469668696dcSAl Viro if (IS_ERR(name)) 2470668696dcSAl Viro return PTR_ERR(name); 2471756daf26SNeilBrown saved = set_nameidata(&nd); 247246afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_RCU); 24732d864651SAl Viro if (unlikely(error == -ECHILD)) 247446afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags); 24752d864651SAl Viro if (unlikely(error == -ESTALE)) 247646afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_REVAL); 24772d864651SAl Viro if (likely(!error)) 2478668696dcSAl Viro audit_inode(name, path->dentry, 0); 2479756daf26SNeilBrown restore_nameidata(saved); 2480668696dcSAl Viro putname(name); 24812d864651SAl Viro return error; 24822d864651SAl Viro } 24832d864651SAl Viro 24848033426eSJeff Layton /** 2485197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 24868033426eSJeff Layton * @dfd: directory file descriptor 24878033426eSJeff Layton * @name: pathname from userland 24888033426eSJeff Layton * @flags: lookup flags 24898033426eSJeff Layton * @path: pointer to container to hold result 24908033426eSJeff Layton * 24918033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 24928033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 24938033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 24948033426eSJeff Layton * and avoid revalidating the last component. 24958033426eSJeff Layton * 24968033426eSJeff Layton * Returns 0 and populates "path" on success. 24978033426eSJeff Layton */ 24988033426eSJeff Layton int 2499197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 25008033426eSJeff Layton struct path *path) 25018033426eSJeff Layton { 2502cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 25038033426eSJeff Layton } 25048033426eSJeff Layton 25052d864651SAl Viro int 25062d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 25072d864651SAl Viro unsigned int flags) 25082d864651SAl Viro { 2509cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 25102d864651SAl Viro } 25112d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 25122d864651SAl Viro 2513cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 25141da177e4SLinus Torvalds { 25158e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2516da9592edSDavid Howells 25178e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 25181da177e4SLinus Torvalds return 0; 25198e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 25201da177e4SLinus Torvalds return 0; 252123adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 25221da177e4SLinus Torvalds } 2523cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 25241da177e4SLinus Torvalds 25251da177e4SLinus Torvalds /* 25261da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 25271da177e4SLinus Torvalds * whether the type of victim is right. 25281da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 25291da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 25301da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 25311da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 25321da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 25331da177e4SLinus Torvalds * a. be owner of dir, or 25341da177e4SLinus Torvalds * b. be owner of victim, or 25351da177e4SLinus Torvalds * c. have CAP_FOWNER capability 25361da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 25371da177e4SLinus Torvalds * links pointing to it. 25381da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 25391da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 25401da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 25411da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 25421da177e4SLinus Torvalds * nfs_async_unlink(). 25431da177e4SLinus Torvalds */ 2544b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 25451da177e4SLinus Torvalds { 254663afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 25471da177e4SLinus Torvalds int error; 25481da177e4SLinus Torvalds 2549b18825a7SDavid Howells if (d_is_negative(victim)) 25501da177e4SLinus Torvalds return -ENOENT; 2551b18825a7SDavid Howells BUG_ON(!inode); 25521da177e4SLinus Torvalds 25531da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 25544fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 25551da177e4SLinus Torvalds 2556f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 25571da177e4SLinus Torvalds if (error) 25581da177e4SLinus Torvalds return error; 25591da177e4SLinus Torvalds if (IS_APPEND(dir)) 25601da177e4SLinus Torvalds return -EPERM; 2561b18825a7SDavid Howells 2562b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2563b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 25641da177e4SLinus Torvalds return -EPERM; 25651da177e4SLinus Torvalds if (isdir) { 256644b1d530SMiklos Szeredi if (!d_is_dir(victim)) 25671da177e4SLinus Torvalds return -ENOTDIR; 25681da177e4SLinus Torvalds if (IS_ROOT(victim)) 25691da177e4SLinus Torvalds return -EBUSY; 257044b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 25711da177e4SLinus Torvalds return -EISDIR; 25721da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25731da177e4SLinus Torvalds return -ENOENT; 25741da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 25751da177e4SLinus Torvalds return -EBUSY; 25761da177e4SLinus Torvalds return 0; 25771da177e4SLinus Torvalds } 25781da177e4SLinus Torvalds 25791da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 25801da177e4SLinus Torvalds * dir. 25811da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 25821da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 25831da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 25841da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 25851da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 25861da177e4SLinus Torvalds */ 2587a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 25881da177e4SLinus Torvalds { 258914e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 25901da177e4SLinus Torvalds if (child->d_inode) 25911da177e4SLinus Torvalds return -EEXIST; 25921da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25931da177e4SLinus Torvalds return -ENOENT; 2594f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 25951da177e4SLinus Torvalds } 25961da177e4SLinus Torvalds 25971da177e4SLinus Torvalds /* 25981da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 25991da177e4SLinus Torvalds */ 26001da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 26011da177e4SLinus Torvalds { 26021da177e4SLinus Torvalds struct dentry *p; 26031da177e4SLinus Torvalds 26041da177e4SLinus Torvalds if (p1 == p2) { 2605f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 26061da177e4SLinus Torvalds return NULL; 26071da177e4SLinus Torvalds } 26081da177e4SLinus Torvalds 2609a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 26101da177e4SLinus Torvalds 2611e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2612e2761a11SOGAWA Hirofumi if (p) { 2613f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2614f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 26151da177e4SLinus Torvalds return p; 26161da177e4SLinus Torvalds } 26171da177e4SLinus Torvalds 2618e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2619e2761a11SOGAWA Hirofumi if (p) { 2620f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2621f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 26221da177e4SLinus Torvalds return p; 26231da177e4SLinus Torvalds } 26241da177e4SLinus Torvalds 2625f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2626d1b72cc6SMiklos Szeredi mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); 26271da177e4SLinus Torvalds return NULL; 26281da177e4SLinus Torvalds } 26294d359507SAl Viro EXPORT_SYMBOL(lock_rename); 26301da177e4SLinus Torvalds 26311da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 26321da177e4SLinus Torvalds { 26331b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 26341da177e4SLinus Torvalds if (p1 != p2) { 26351b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2636a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 26371da177e4SLinus Torvalds } 26381da177e4SLinus Torvalds } 26394d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 26401da177e4SLinus Torvalds 26414acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2642312b63fbSAl Viro bool want_excl) 26431da177e4SLinus Torvalds { 2644a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 26451da177e4SLinus Torvalds if (error) 26461da177e4SLinus Torvalds return error; 26471da177e4SLinus Torvalds 2648acfa4380SAl Viro if (!dir->i_op->create) 26491da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 26501da177e4SLinus Torvalds mode &= S_IALLUGO; 26511da177e4SLinus Torvalds mode |= S_IFREG; 26521da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 26531da177e4SLinus Torvalds if (error) 26541da177e4SLinus Torvalds return error; 2655312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2656a74574aaSStephen Smalley if (!error) 2657f38aa942SAmy Griffis fsnotify_create(dir, dentry); 26581da177e4SLinus Torvalds return error; 26591da177e4SLinus Torvalds } 26604d359507SAl Viro EXPORT_SYMBOL(vfs_create); 26611da177e4SLinus Torvalds 266273d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 26631da177e4SLinus Torvalds { 26643fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 26651da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 26661da177e4SLinus Torvalds int error; 26671da177e4SLinus Torvalds 2668bcda7652SAl Viro /* O_PATH? */ 2669bcda7652SAl Viro if (!acc_mode) 2670bcda7652SAl Viro return 0; 2671bcda7652SAl Viro 26721da177e4SLinus Torvalds if (!inode) 26731da177e4SLinus Torvalds return -ENOENT; 26741da177e4SLinus Torvalds 2675c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2676c8fe8f30SChristoph Hellwig case S_IFLNK: 26771da177e4SLinus Torvalds return -ELOOP; 2678c8fe8f30SChristoph Hellwig case S_IFDIR: 2679c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 26801da177e4SLinus Torvalds return -EISDIR; 2681c8fe8f30SChristoph Hellwig break; 2682c8fe8f30SChristoph Hellwig case S_IFBLK: 2683c8fe8f30SChristoph Hellwig case S_IFCHR: 26843fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 26851da177e4SLinus Torvalds return -EACCES; 2686c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2687c8fe8f30SChristoph Hellwig case S_IFIFO: 2688c8fe8f30SChristoph Hellwig case S_IFSOCK: 26891da177e4SLinus Torvalds flag &= ~O_TRUNC; 2690c8fe8f30SChristoph Hellwig break; 26914a3fd211SDave Hansen } 2692b41572e9SDave Hansen 26933fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2694b41572e9SDave Hansen if (error) 2695b41572e9SDave Hansen return error; 26966146f0d5SMimi Zohar 26971da177e4SLinus Torvalds /* 26981da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 26991da177e4SLinus Torvalds */ 27001da177e4SLinus Torvalds if (IS_APPEND(inode)) { 27018737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 27027715b521SAl Viro return -EPERM; 27031da177e4SLinus Torvalds if (flag & O_TRUNC) 27047715b521SAl Viro return -EPERM; 27051da177e4SLinus Torvalds } 27061da177e4SLinus Torvalds 27071da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 27082e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 27097715b521SAl Viro return -EPERM; 27101da177e4SLinus Torvalds 2711f3c7691eSJ. Bruce Fields return 0; 27127715b521SAl Viro } 27137715b521SAl Viro 2714e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 27157715b521SAl Viro { 2716e1181ee6SJeff Layton struct path *path = &filp->f_path; 27177715b521SAl Viro struct inode *inode = path->dentry->d_inode; 27187715b521SAl Viro int error = get_write_access(inode); 27191da177e4SLinus Torvalds if (error) 27207715b521SAl Viro return error; 27211da177e4SLinus Torvalds /* 27221da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 27231da177e4SLinus Torvalds */ 2724d7a06983SJeff Layton error = locks_verify_locked(filp); 2725be6d3e56SKentaro Takeda if (!error) 2726ea0d3ab2STetsuo Handa error = security_path_truncate(path); 27271da177e4SLinus Torvalds if (!error) { 27287715b521SAl Viro error = do_truncate(path->dentry, 0, 2729d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2730e1181ee6SJeff Layton filp); 27311da177e4SLinus Torvalds } 27321da177e4SLinus Torvalds put_write_access(inode); 2733acd0c935SMimi Zohar return error; 27341da177e4SLinus Torvalds } 27351da177e4SLinus Torvalds 2736d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2737d57999e1SDave Hansen { 27388a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 27398a5e929dSAl Viro flag--; 2740d57999e1SDave Hansen return flag; 2741d57999e1SDave Hansen } 2742d57999e1SDave Hansen 2743d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2744d18e9008SMiklos Szeredi { 2745d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2746d18e9008SMiklos Szeredi if (error) 2747d18e9008SMiklos Szeredi return error; 2748d18e9008SMiklos Szeredi 2749d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2750d18e9008SMiklos Szeredi if (error) 2751d18e9008SMiklos Szeredi return error; 2752d18e9008SMiklos Szeredi 2753d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2754d18e9008SMiklos Szeredi } 2755d18e9008SMiklos Szeredi 27561acf0af9SDavid Howells /* 27571acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 27581acf0af9SDavid Howells * dentry. 27591acf0af9SDavid Howells * 27601acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 27611acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 27621acf0af9SDavid Howells * 27631acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 27641acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 27651acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 27661acf0af9SDavid Howells * 27671acf0af9SDavid Howells * Returns an error code otherwise. 27681acf0af9SDavid Howells */ 27692675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 277030d90494SAl Viro struct path *path, struct file *file, 2771015c3bbcSMiklos Szeredi const struct open_flags *op, 277264894cf8SAl Viro bool got_write, bool need_lookup, 277347237687SAl Viro int *opened) 2774d18e9008SMiklos Szeredi { 2775d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2776d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2777d18e9008SMiklos Szeredi umode_t mode; 2778d18e9008SMiklos Szeredi int error; 2779d18e9008SMiklos Szeredi int acc_mode; 2780d18e9008SMiklos Szeredi int create_error = 0; 2781d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2782116cc022SMiklos Szeredi bool excl; 2783d18e9008SMiklos Szeredi 2784d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2785d18e9008SMiklos Szeredi 2786d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2787d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 27882675a4ebSAl Viro error = -ENOENT; 2789d18e9008SMiklos Szeredi goto out; 2790d18e9008SMiklos Szeredi } 2791d18e9008SMiklos Szeredi 279262b259d8SMiklos Szeredi mode = op->mode; 2793d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2794d18e9008SMiklos Szeredi mode &= ~current_umask(); 2795d18e9008SMiklos Szeredi 2796116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2797116cc022SMiklos Szeredi if (excl) 2798d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2799d18e9008SMiklos Szeredi 2800d18e9008SMiklos Szeredi /* 2801d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2802d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2803d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2804d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2805d18e9008SMiklos Szeredi * 2806d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2807d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2808d18e9008SMiklos Szeredi */ 280964894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 281064894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 281164894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2812d18e9008SMiklos Szeredi /* 2813d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2814d18e9008SMiklos Szeredi * back to lookup + open 2815d18e9008SMiklos Szeredi */ 2816d18e9008SMiklos Szeredi goto no_open; 2817d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2818d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 281964894cf8SAl Viro create_error = -EROFS; 2820d18e9008SMiklos Szeredi goto no_open; 2821d18e9008SMiklos Szeredi } else { 2822d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 282364894cf8SAl Viro create_error = -EROFS; 2824d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2825d18e9008SMiklos Szeredi } 2826d18e9008SMiklos Szeredi } 2827d18e9008SMiklos Szeredi 2828d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 282938227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2830d18e9008SMiklos Szeredi if (error) { 2831d18e9008SMiklos Szeredi create_error = error; 2832d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2833d18e9008SMiklos Szeredi goto no_open; 2834d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2835d18e9008SMiklos Szeredi } 2836d18e9008SMiklos Szeredi } 2837d18e9008SMiklos Szeredi 2838d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2839d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2840d18e9008SMiklos Szeredi 284130d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 284230d90494SAl Viro file->f_path.mnt = nd->path.mnt; 284330d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 284447237687SAl Viro opened); 2845d9585277SAl Viro if (error < 0) { 2846d9585277SAl Viro if (create_error && error == -ENOENT) 2847d9585277SAl Viro error = create_error; 2848d18e9008SMiklos Szeredi goto out; 2849d18e9008SMiklos Szeredi } 2850d18e9008SMiklos Szeredi 2851d9585277SAl Viro if (error) { /* returned 1, that is */ 285230d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 28532675a4ebSAl Viro error = -EIO; 2854d18e9008SMiklos Szeredi goto out; 2855d18e9008SMiklos Szeredi } 285630d90494SAl Viro if (file->f_path.dentry) { 2857d18e9008SMiklos Szeredi dput(dentry); 285830d90494SAl Viro dentry = file->f_path.dentry; 2859d18e9008SMiklos Szeredi } 286003da633aSAl Viro if (*opened & FILE_CREATED) 286103da633aSAl Viro fsnotify_create(dir, dentry); 286203da633aSAl Viro if (!dentry->d_inode) { 286303da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 286403da633aSAl Viro if (create_error) { 286562b2ce96SSage Weil error = create_error; 286662b2ce96SSage Weil goto out; 286762b2ce96SSage Weil } 286803da633aSAl Viro } else { 286903da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 287003da633aSAl Viro error = -EEXIST; 287103da633aSAl Viro goto out; 287203da633aSAl Viro } 287303da633aSAl Viro } 2874d18e9008SMiklos Szeredi goto looked_up; 2875d18e9008SMiklos Szeredi } 2876d18e9008SMiklos Szeredi 2877d18e9008SMiklos Szeredi /* 2878d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2879d18e9008SMiklos Szeredi * here. 2880d18e9008SMiklos Szeredi */ 288103da633aSAl Viro acc_mode = op->acc_mode; 288203da633aSAl Viro if (*opened & FILE_CREATED) { 288303da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 288403da633aSAl Viro fsnotify_create(dir, dentry); 288503da633aSAl Viro acc_mode = MAY_OPEN; 288603da633aSAl Viro } 28872675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 28882675a4ebSAl Viro if (error) 28892675a4ebSAl Viro fput(file); 2890d18e9008SMiklos Szeredi 2891d18e9008SMiklos Szeredi out: 2892d18e9008SMiklos Szeredi dput(dentry); 28932675a4ebSAl Viro return error; 2894d18e9008SMiklos Szeredi 2895d18e9008SMiklos Szeredi no_open: 2896d18e9008SMiklos Szeredi if (need_lookup) { 289772bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2898d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 28992675a4ebSAl Viro return PTR_ERR(dentry); 2900d18e9008SMiklos Szeredi 2901d18e9008SMiklos Szeredi if (create_error) { 2902d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2903d18e9008SMiklos Szeredi 29042675a4ebSAl Viro error = create_error; 2905d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2906d18e9008SMiklos Szeredi if (!dentry->d_inode) 2907d18e9008SMiklos Szeredi goto out; 2908d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2909d18e9008SMiklos Szeredi goto out; 2910d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2911e36cb0b8SDavid Howells d_is_reg(dentry)) { 2912d18e9008SMiklos Szeredi goto out; 2913d18e9008SMiklos Szeredi } 2914d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2915d18e9008SMiklos Szeredi } 2916d18e9008SMiklos Szeredi } 2917d18e9008SMiklos Szeredi looked_up: 2918d18e9008SMiklos Szeredi path->dentry = dentry; 2919d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 29202675a4ebSAl Viro return 1; 2921d18e9008SMiklos Szeredi } 2922d18e9008SMiklos Szeredi 292331e6b01fSNick Piggin /* 29241acf0af9SDavid Howells * Look up and maybe create and open the last component. 2925d58ffd35SMiklos Szeredi * 2926d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2927d58ffd35SMiklos Szeredi * 29281acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 29291acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 29301acf0af9SDavid Howells * 29311acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 29321acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 29331acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 29341acf0af9SDavid Howells * specified then a negative dentry may be returned. 29351acf0af9SDavid Howells * 29361acf0af9SDavid Howells * An error code is returned otherwise. 29371acf0af9SDavid Howells * 29381acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 29391acf0af9SDavid Howells * cleared otherwise prior to returning. 2940d58ffd35SMiklos Szeredi */ 29412675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 294230d90494SAl Viro struct file *file, 2943d58ffd35SMiklos Szeredi const struct open_flags *op, 294464894cf8SAl Viro bool got_write, int *opened) 2945d58ffd35SMiklos Szeredi { 2946d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 294754ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2948d58ffd35SMiklos Szeredi struct dentry *dentry; 2949d58ffd35SMiklos Szeredi int error; 295054ef4872SMiklos Szeredi bool need_lookup; 2951d58ffd35SMiklos Szeredi 295247237687SAl Viro *opened &= ~FILE_CREATED; 2953201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2954d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 29552675a4ebSAl Viro return PTR_ERR(dentry); 2956d58ffd35SMiklos Szeredi 2957d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2958d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2959d18e9008SMiklos Szeredi goto out_no_open; 2960d18e9008SMiklos Szeredi 2961d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 296264894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 296347237687SAl Viro need_lookup, opened); 2964d18e9008SMiklos Szeredi } 2965d18e9008SMiklos Szeredi 296654ef4872SMiklos Szeredi if (need_lookup) { 296754ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 296854ef4872SMiklos Szeredi 296972bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 297054ef4872SMiklos Szeredi if (IS_ERR(dentry)) 29712675a4ebSAl Viro return PTR_ERR(dentry); 297254ef4872SMiklos Szeredi } 297354ef4872SMiklos Szeredi 2974d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2975d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2976d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2977d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2978d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2979d58ffd35SMiklos Szeredi /* 2980d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2981d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2982d58ffd35SMiklos Szeredi * the time when the file is created and when 2983d58ffd35SMiklos Szeredi * a permanent write count is taken through 2984015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 2985d58ffd35SMiklos Szeredi */ 298664894cf8SAl Viro if (!got_write) { 298764894cf8SAl Viro error = -EROFS; 2988d58ffd35SMiklos Szeredi goto out_dput; 298964894cf8SAl Viro } 299047237687SAl Viro *opened |= FILE_CREATED; 2991d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2992d58ffd35SMiklos Szeredi if (error) 2993d58ffd35SMiklos Szeredi goto out_dput; 2994312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 2995312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 2996d58ffd35SMiklos Szeredi if (error) 2997d58ffd35SMiklos Szeredi goto out_dput; 2998d58ffd35SMiklos Szeredi } 2999d18e9008SMiklos Szeredi out_no_open: 3000d58ffd35SMiklos Szeredi path->dentry = dentry; 3001d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 30022675a4ebSAl Viro return 1; 3003d58ffd35SMiklos Szeredi 3004d58ffd35SMiklos Szeredi out_dput: 3005d58ffd35SMiklos Szeredi dput(dentry); 30062675a4ebSAl Viro return error; 3007d58ffd35SMiklos Szeredi } 3008d58ffd35SMiklos Szeredi 3009d58ffd35SMiklos Szeredi /* 3010fe2d35ffSAl Viro * Handle the last step of open() 301131e6b01fSNick Piggin */ 3012896475d5SAl Viro static int do_last(struct nameidata *nd, 301330d90494SAl Viro struct file *file, const struct open_flags *op, 3014669abf4eSJeff Layton int *opened, struct filename *name) 3015fb1cc555SAl Viro { 3016a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3017ca344a89SAl Viro int open_flag = op->open_flag; 301877d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 301964894cf8SAl Viro bool got_write = false; 3020bcda7652SAl Viro int acc_mode = op->acc_mode; 3021254cf582SAl Viro unsigned seq; 3022a1eb3315SMiklos Szeredi struct inode *inode; 302316b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 3024896475d5SAl Viro struct path path; 302516b1c1cdSMiklos Szeredi bool retried = false; 302616c2cd71SAl Viro int error; 3027fb1cc555SAl Viro 3028c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3029c3e380b0SAl Viro nd->flags |= op->intent; 3030c3e380b0SAl Viro 3031bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3032fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3033deb106c6SAl Viro if (unlikely(error)) 30342675a4ebSAl Viro return error; 3035e83db167SMiklos Szeredi goto finish_open; 30361f36f774SAl Viro } 3037a2c36b45SAl Viro 3038ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3039fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3040fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3041fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3042254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 304371574865SMiklos Szeredi if (likely(!error)) 304471574865SMiklos Szeredi goto finish_lookup; 304571574865SMiklos Szeredi 3046ce57dfc1SAl Viro if (error < 0) 3047deb106c6SAl Viro return error; 3048a1eb3315SMiklos Szeredi 304937d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 3050b6183df7SMiklos Szeredi } else { 3051fe2d35ffSAl Viro /* create side of things */ 3052a3fbbde7SAl Viro /* 3053b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3054b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3055b6183df7SMiklos Szeredi * about to look up 3056a3fbbde7SAl Viro */ 30579f1fafeeSAl Viro error = complete_walk(nd); 3058e8bb73dfSAl Viro if (error) 30592675a4ebSAl Viro return error; 3060fe2d35ffSAl Viro 306133e2208aSJeff Layton audit_inode(name, dir, LOOKUP_PARENT); 30621f36f774SAl Viro /* trailing slashes? */ 3063deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3064deb106c6SAl Viro return -EISDIR; 3065b6183df7SMiklos Szeredi } 30661f36f774SAl Viro 306716b1c1cdSMiklos Szeredi retry_lookup: 306864894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 306964894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 307064894cf8SAl Viro if (!error) 307164894cf8SAl Viro got_write = true; 307264894cf8SAl Viro /* 307364894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 307464894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 307564894cf8SAl Viro * dropping this one anyway. 307664894cf8SAl Viro */ 307764894cf8SAl Viro } 3078a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 3079896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 3080fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 3081fb1cc555SAl Viro 30822675a4ebSAl Viro if (error <= 0) { 30832675a4ebSAl Viro if (error) 3084d58ffd35SMiklos Szeredi goto out; 30856c0d46c4SAl Viro 308647237687SAl Viro if ((*opened & FILE_CREATED) || 3087496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 308877d660a8SMiklos Szeredi will_truncate = false; 3089d18e9008SMiklos Szeredi 3090adb5c247SJeff Layton audit_inode(name, file->f_path.dentry, 0); 3091d18e9008SMiklos Szeredi goto opened; 3092d18e9008SMiklos Szeredi } 3093d18e9008SMiklos Szeredi 309447237687SAl Viro if (*opened & FILE_CREATED) { 30959b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3096ca344a89SAl Viro open_flag &= ~O_TRUNC; 309777d660a8SMiklos Szeredi will_truncate = false; 3098bcda7652SAl Viro acc_mode = MAY_OPEN; 3099896475d5SAl Viro path_to_nameidata(&path, nd); 3100e83db167SMiklos Szeredi goto finish_open_created; 3101fb1cc555SAl Viro } 3102fb1cc555SAl Viro 3103fb1cc555SAl Viro /* 31043134f37eSJeff Layton * create/update audit record if it already exists. 3105fb1cc555SAl Viro */ 3106896475d5SAl Viro if (d_is_positive(path.dentry)) 3107896475d5SAl Viro audit_inode(name, path.dentry, 0); 3108fb1cc555SAl Viro 3109d18e9008SMiklos Szeredi /* 3110d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3111d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3112d18e9008SMiklos Szeredi * necessary...) 3113d18e9008SMiklos Szeredi */ 311464894cf8SAl Viro if (got_write) { 3115d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 311664894cf8SAl Viro got_write = false; 3117d18e9008SMiklos Szeredi } 3118d18e9008SMiklos Szeredi 3119deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3120deb106c6SAl Viro path_to_nameidata(&path, nd); 3121deb106c6SAl Viro return -EEXIST; 3122deb106c6SAl Viro } 3123fb1cc555SAl Viro 3124756daf26SNeilBrown error = follow_managed(&path, nd); 3125deb106c6SAl Viro if (unlikely(error < 0)) 3126deb106c6SAl Viro return error; 3127a3fbbde7SAl Viro 3128decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 312963afdfc7SDavid Howells inode = d_backing_inode(path.dentry); 3130254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3131deb106c6SAl Viro if (unlikely(d_is_negative(path.dentry))) { 3132896475d5SAl Viro path_to_nameidata(&path, nd); 3133deb106c6SAl Viro return -ENOENT; 313454c33e7fSMiklos Szeredi } 3135766c4cbfSAl Viro finish_lookup: 3136191d7f73SAl Viro if (nd->depth) 3137191d7f73SAl Viro put_link(nd); 3138181548c0SAl Viro error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW, 3139181548c0SAl Viro inode, seq); 3140deb106c6SAl Viro if (unlikely(error)) 3141d63ff28fSAl Viro return error; 3142fb1cc555SAl Viro 3143896475d5SAl Viro if (unlikely(d_is_symlink(path.dentry)) && !(open_flag & O_PATH)) { 3144896475d5SAl Viro path_to_nameidata(&path, nd); 3145deb106c6SAl Viro return -ELOOP; 3146a5cfe2d5SAl Viro } 3147a5cfe2d5SAl Viro 3148896475d5SAl Viro if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { 3149896475d5SAl Viro path_to_nameidata(&path, nd); 315016b1c1cdSMiklos Szeredi } else { 315116b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 3152896475d5SAl Viro save_parent.mnt = mntget(path.mnt); 3153896475d5SAl Viro nd->path.dentry = path.dentry; 315416b1c1cdSMiklos Szeredi 315516b1c1cdSMiklos Szeredi } 3156decf3400SMiklos Szeredi nd->inode = inode; 3157254cf582SAl Viro nd->seq = seq; 3158a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3159bc77daa7SAl Viro finish_open: 3160a3fbbde7SAl Viro error = complete_walk(nd); 316116b1c1cdSMiklos Szeredi if (error) { 316216b1c1cdSMiklos Szeredi path_put(&save_parent); 31632675a4ebSAl Viro return error; 316416b1c1cdSMiklos Szeredi } 3165bc77daa7SAl Viro audit_inode(name, nd->path.dentry, 0); 3166fb1cc555SAl Viro error = -EISDIR; 316744b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 31682675a4ebSAl Viro goto out; 3169af2f5542SMiklos Szeredi error = -ENOTDIR; 317044b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 31712675a4ebSAl Viro goto out; 31724bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 317377d660a8SMiklos Szeredi will_truncate = false; 31746c0d46c4SAl Viro 31750f9d1a10SAl Viro if (will_truncate) { 31760f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 31770f9d1a10SAl Viro if (error) 31782675a4ebSAl Viro goto out; 317964894cf8SAl Viro got_write = true; 31800f9d1a10SAl Viro } 3181e83db167SMiklos Szeredi finish_open_created: 3182bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3183ca344a89SAl Viro if (error) 31842675a4ebSAl Viro goto out; 31854aa7c634SMiklos Szeredi 31864aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 31874aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 31884aa7c634SMiklos Szeredi if (!error) { 31894aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 31904aa7c634SMiklos Szeredi } else { 319130d90494SAl Viro if (error == -EOPENSTALE) 3192f60dc3dbSMiklos Szeredi goto stale_open; 3193015c3bbcSMiklos Szeredi goto out; 3194f60dc3dbSMiklos Szeredi } 3195a8277b9bSMiklos Szeredi opened: 31962675a4ebSAl Viro error = open_check_o_direct(file); 3197015c3bbcSMiklos Szeredi if (error) 3198015c3bbcSMiklos Szeredi goto exit_fput; 31993034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3200aa4caadbSMiklos Szeredi if (error) 3201aa4caadbSMiklos Szeredi goto exit_fput; 3202aa4caadbSMiklos Szeredi 32030f9d1a10SAl Viro if (will_truncate) { 32042675a4ebSAl Viro error = handle_truncate(file); 3205aa4caadbSMiklos Szeredi if (error) 3206aa4caadbSMiklos Szeredi goto exit_fput; 32070f9d1a10SAl Viro } 3208ca344a89SAl Viro out: 320964894cf8SAl Viro if (got_write) 32100f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 321116b1c1cdSMiklos Szeredi path_put(&save_parent); 32122675a4ebSAl Viro return error; 3213fb1cc555SAl Viro 3214015c3bbcSMiklos Szeredi exit_fput: 32152675a4ebSAl Viro fput(file); 32162675a4ebSAl Viro goto out; 3217015c3bbcSMiklos Szeredi 3218f60dc3dbSMiklos Szeredi stale_open: 3219f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3220f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3221f60dc3dbSMiklos Szeredi goto out; 3222f60dc3dbSMiklos Szeredi 3223f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3224f60dc3dbSMiklos Szeredi path_put(&nd->path); 3225f60dc3dbSMiklos Szeredi nd->path = save_parent; 3226f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3227f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3228f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 322964894cf8SAl Viro if (got_write) { 3230f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 323164894cf8SAl Viro got_write = false; 3232f60dc3dbSMiklos Szeredi } 3233f60dc3dbSMiklos Szeredi retried = true; 3234f60dc3dbSMiklos Szeredi goto retry_lookup; 3235fb1cc555SAl Viro } 3236fb1cc555SAl Viro 323760545d0dSAl Viro static int do_tmpfile(int dfd, struct filename *pathname, 323860545d0dSAl Viro struct nameidata *nd, int flags, 323960545d0dSAl Viro const struct open_flags *op, 324060545d0dSAl Viro struct file *file, int *opened) 324160545d0dSAl Viro { 324260545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 324360545d0dSAl Viro struct dentry *dentry, *child; 324460545d0dSAl Viro struct inode *dir; 32455eb6b495SAl Viro int error = path_lookupat(dfd, pathname, 324660545d0dSAl Viro flags | LOOKUP_DIRECTORY, nd); 324760545d0dSAl Viro if (unlikely(error)) 324860545d0dSAl Viro return error; 324960545d0dSAl Viro error = mnt_want_write(nd->path.mnt); 325060545d0dSAl Viro if (unlikely(error)) 325160545d0dSAl Viro goto out; 325260545d0dSAl Viro /* we want directory to be writable */ 325360545d0dSAl Viro error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); 325460545d0dSAl Viro if (error) 325560545d0dSAl Viro goto out2; 325660545d0dSAl Viro dentry = nd->path.dentry; 325760545d0dSAl Viro dir = dentry->d_inode; 325860545d0dSAl Viro if (!dir->i_op->tmpfile) { 325960545d0dSAl Viro error = -EOPNOTSUPP; 326060545d0dSAl Viro goto out2; 326160545d0dSAl Viro } 326260545d0dSAl Viro child = d_alloc(dentry, &name); 326360545d0dSAl Viro if (unlikely(!child)) { 326460545d0dSAl Viro error = -ENOMEM; 326560545d0dSAl Viro goto out2; 326660545d0dSAl Viro } 326760545d0dSAl Viro nd->flags &= ~LOOKUP_DIRECTORY; 326860545d0dSAl Viro nd->flags |= op->intent; 326960545d0dSAl Viro dput(nd->path.dentry); 327060545d0dSAl Viro nd->path.dentry = child; 327160545d0dSAl Viro error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); 327260545d0dSAl Viro if (error) 327360545d0dSAl Viro goto out2; 327460545d0dSAl Viro audit_inode(pathname, nd->path.dentry, 0); 327569a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 327669a91c23SEric Rannaud error = may_open(&nd->path, MAY_OPEN, op->open_flag); 327760545d0dSAl Viro if (error) 327860545d0dSAl Viro goto out2; 327960545d0dSAl Viro file->f_path.mnt = nd->path.mnt; 328060545d0dSAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 328160545d0dSAl Viro if (error) 328260545d0dSAl Viro goto out2; 328360545d0dSAl Viro error = open_check_o_direct(file); 3284f4e0c30cSAl Viro if (error) { 328560545d0dSAl Viro fput(file); 3286f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3287f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3288f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3289f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3290f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3291f4e0c30cSAl Viro } 329260545d0dSAl Viro out2: 329360545d0dSAl Viro mnt_drop_write(nd->path.mnt); 329460545d0dSAl Viro out: 329560545d0dSAl Viro path_put(&nd->path); 329660545d0dSAl Viro return error; 329760545d0dSAl Viro } 329860545d0dSAl Viro 3299669abf4eSJeff Layton static struct file *path_openat(int dfd, struct filename *pathname, 330073d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 33011da177e4SLinus Torvalds { 3302368ee9baSAl Viro const char *s; 330330d90494SAl Viro struct file *file; 330447237687SAl Viro int opened = 0; 330513aab428SAl Viro int error; 330631e6b01fSNick Piggin 330730d90494SAl Viro file = get_empty_filp(); 33081afc99beSAl Viro if (IS_ERR(file)) 33091afc99beSAl Viro return file; 331031e6b01fSNick Piggin 331130d90494SAl Viro file->f_flags = op->open_flag; 331231e6b01fSNick Piggin 3313bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 331460545d0dSAl Viro error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); 3315f15133dfSAl Viro goto out2; 331660545d0dSAl Viro } 331760545d0dSAl Viro 3318368ee9baSAl Viro s = path_init(dfd, pathname, flags, nd); 3319368ee9baSAl Viro if (IS_ERR(s)) { 3320368ee9baSAl Viro put_filp(file); 3321368ee9baSAl Viro return ERR_CAST(s); 3322368ee9baSAl Viro } 33233bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 33243bdba28bSAl Viro (error = do_last(nd, file, op, &opened, pathname)) > 0) { 332573d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 33263bdba28bSAl Viro s = trailing_symlink(nd); 33273bdba28bSAl Viro if (IS_ERR(s)) { 33283bdba28bSAl Viro error = PTR_ERR(s); 33292675a4ebSAl Viro break; 3330806b681cSAl Viro } 33313bdba28bSAl Viro } 3332deb106c6SAl Viro terminate_walk(nd); 3333893b7775SAl Viro path_cleanup(nd); 3334f15133dfSAl Viro out2: 33352675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 33362675a4ebSAl Viro BUG_ON(!error); 333730d90494SAl Viro put_filp(file); 3338015c3bbcSMiklos Szeredi } 33392675a4ebSAl Viro if (unlikely(error)) { 33402675a4ebSAl Viro if (error == -EOPENSTALE) { 33412675a4ebSAl Viro if (flags & LOOKUP_RCU) 33422675a4ebSAl Viro error = -ECHILD; 33432675a4ebSAl Viro else 33442675a4ebSAl Viro error = -ESTALE; 33452675a4ebSAl Viro } 33462675a4ebSAl Viro file = ERR_PTR(error); 33472675a4ebSAl Viro } 33482675a4ebSAl Viro return file; 3349de459215SKirill Korotaev } 33501da177e4SLinus Torvalds 3351669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3352f9652e10SAl Viro const struct open_flags *op) 335313aab428SAl Viro { 3354756daf26SNeilBrown struct nameidata nd, *saved_nd = set_nameidata(&nd); 3355f9652e10SAl Viro int flags = op->lookup_flags; 335613aab428SAl Viro struct file *filp; 335713aab428SAl Viro 335873d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 335913aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 336073d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 336113aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 336273d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 3363756daf26SNeilBrown restore_nameidata(saved_nd); 336413aab428SAl Viro return filp; 336513aab428SAl Viro } 336613aab428SAl Viro 336773d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3368f9652e10SAl Viro const char *name, const struct open_flags *op) 336973d049a4SAl Viro { 3370756daf26SNeilBrown struct nameidata nd, *saved_nd; 337173d049a4SAl Viro struct file *file; 337251689104SPaul Moore struct filename *filename; 3373f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 337473d049a4SAl Viro 337573d049a4SAl Viro nd.root.mnt = mnt; 337673d049a4SAl Viro nd.root.dentry = dentry; 337773d049a4SAl Viro 3378b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 337973d049a4SAl Viro return ERR_PTR(-ELOOP); 338073d049a4SAl Viro 338151689104SPaul Moore filename = getname_kernel(name); 338251689104SPaul Moore if (unlikely(IS_ERR(filename))) 338351689104SPaul Moore return ERR_CAST(filename); 338451689104SPaul Moore 3385756daf26SNeilBrown saved_nd = set_nameidata(&nd); 338651689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_RCU); 338773d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 338851689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags); 338973d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 339051689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_REVAL); 3391756daf26SNeilBrown restore_nameidata(saved_nd); 339251689104SPaul Moore putname(filename); 339373d049a4SAl Viro return file; 339473d049a4SAl Viro } 339573d049a4SAl Viro 3396fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 33971ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 33981da177e4SLinus Torvalds { 3399c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3400ed75e95dSAl Viro struct nameidata nd; 3401c30dabfeSJan Kara int err2; 34021ac12b4bSJeff Layton int error; 34031ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 34041ac12b4bSJeff Layton 34051ac12b4bSJeff Layton /* 34061ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 34071ac12b4bSJeff Layton * other flags passed in are ignored! 34081ac12b4bSJeff Layton */ 34091ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 34101ac12b4bSJeff Layton 34118bcb77faSAl Viro error = filename_parentat(dfd, name, lookup_flags, &nd); 3412ed75e95dSAl Viro if (error) 3413ed75e95dSAl Viro return ERR_PTR(error); 34141da177e4SLinus Torvalds 3415c663e5d8SChristoph Hellwig /* 3416c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3417c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3418c663e5d8SChristoph Hellwig */ 3419ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 3420ed75e95dSAl Viro goto out; 3421ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 3422ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 3423c663e5d8SChristoph Hellwig 3424c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3425c30dabfeSJan Kara err2 = mnt_want_write(nd.path.mnt); 3426c663e5d8SChristoph Hellwig /* 3427c663e5d8SChristoph Hellwig * Do the final lookup. 3428c663e5d8SChristoph Hellwig */ 3429ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 34306a9f40d6SAl Viro dentry = __lookup_hash(&nd.last, nd.path.dentry, nd.flags); 34311da177e4SLinus Torvalds if (IS_ERR(dentry)) 3432a8104a9fSAl Viro goto unlock; 3433c663e5d8SChristoph Hellwig 3434a8104a9fSAl Viro error = -EEXIST; 3435b18825a7SDavid Howells if (d_is_positive(dentry)) 3436a8104a9fSAl Viro goto fail; 3437b18825a7SDavid Howells 3438c663e5d8SChristoph Hellwig /* 3439c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3440c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3441c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3442c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3443c663e5d8SChristoph Hellwig */ 3444ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 3445a8104a9fSAl Viro error = -ENOENT; 3446ed75e95dSAl Viro goto fail; 3447e9baf6e5SAl Viro } 3448c30dabfeSJan Kara if (unlikely(err2)) { 3449c30dabfeSJan Kara error = err2; 3450a8104a9fSAl Viro goto fail; 3451c30dabfeSJan Kara } 3452ed75e95dSAl Viro *path = nd.path; 3453e9baf6e5SAl Viro return dentry; 34541da177e4SLinus Torvalds fail: 3455a8104a9fSAl Viro dput(dentry); 3456a8104a9fSAl Viro dentry = ERR_PTR(error); 3457a8104a9fSAl Viro unlock: 3458dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3459c30dabfeSJan Kara if (!err2) 3460c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 3461ed75e95dSAl Viro out: 3462dae6ad8fSAl Viro path_put(&nd.path); 3463ed75e95dSAl Viro return dentry; 3464dae6ad8fSAl Viro } 3465fa14a0b8SAl Viro 3466fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3467fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3468fa14a0b8SAl Viro { 346951689104SPaul Moore struct filename *filename = getname_kernel(pathname); 347051689104SPaul Moore struct dentry *res; 347151689104SPaul Moore 347251689104SPaul Moore if (IS_ERR(filename)) 347351689104SPaul Moore return ERR_CAST(filename); 347451689104SPaul Moore res = filename_create(dfd, filename, path, lookup_flags); 347551689104SPaul Moore putname(filename); 347651689104SPaul Moore return res; 3477fa14a0b8SAl Viro } 3478dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3479dae6ad8fSAl Viro 3480921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3481921a1650SAl Viro { 3482921a1650SAl Viro dput(dentry); 3483921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3484a8104a9fSAl Viro mnt_drop_write(path->mnt); 3485921a1650SAl Viro path_put(path); 3486921a1650SAl Viro } 3487921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3488921a1650SAl Viro 34891ac12b4bSJeff Layton struct dentry *user_path_create(int dfd, const char __user *pathname, 34901ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3491dae6ad8fSAl Viro { 349291a27b2aSJeff Layton struct filename *tmp = getname(pathname); 3493dae6ad8fSAl Viro struct dentry *res; 3494dae6ad8fSAl Viro if (IS_ERR(tmp)) 3495dae6ad8fSAl Viro return ERR_CAST(tmp); 3496fa14a0b8SAl Viro res = filename_create(dfd, tmp, path, lookup_flags); 3497dae6ad8fSAl Viro putname(tmp); 3498dae6ad8fSAl Viro return res; 3499dae6ad8fSAl Viro } 3500dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3501dae6ad8fSAl Viro 35021a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 35031da177e4SLinus Torvalds { 3504a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35051da177e4SLinus Torvalds 35061da177e4SLinus Torvalds if (error) 35071da177e4SLinus Torvalds return error; 35081da177e4SLinus Torvalds 3509975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 35101da177e4SLinus Torvalds return -EPERM; 35111da177e4SLinus Torvalds 3512acfa4380SAl Viro if (!dir->i_op->mknod) 35131da177e4SLinus Torvalds return -EPERM; 35141da177e4SLinus Torvalds 351508ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 351608ce5f16SSerge E. Hallyn if (error) 351708ce5f16SSerge E. Hallyn return error; 351808ce5f16SSerge E. Hallyn 35191da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 35201da177e4SLinus Torvalds if (error) 35211da177e4SLinus Torvalds return error; 35221da177e4SLinus Torvalds 35231da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3524a74574aaSStephen Smalley if (!error) 3525f38aa942SAmy Griffis fsnotify_create(dir, dentry); 35261da177e4SLinus Torvalds return error; 35271da177e4SLinus Torvalds } 35284d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 35291da177e4SLinus Torvalds 3530f69aac00SAl Viro static int may_mknod(umode_t mode) 3531463c3197SDave Hansen { 3532463c3197SDave Hansen switch (mode & S_IFMT) { 3533463c3197SDave Hansen case S_IFREG: 3534463c3197SDave Hansen case S_IFCHR: 3535463c3197SDave Hansen case S_IFBLK: 3536463c3197SDave Hansen case S_IFIFO: 3537463c3197SDave Hansen case S_IFSOCK: 3538463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3539463c3197SDave Hansen return 0; 3540463c3197SDave Hansen case S_IFDIR: 3541463c3197SDave Hansen return -EPERM; 3542463c3197SDave Hansen default: 3543463c3197SDave Hansen return -EINVAL; 3544463c3197SDave Hansen } 3545463c3197SDave Hansen } 3546463c3197SDave Hansen 35478208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 35482e4d0924SHeiko Carstens unsigned, dev) 35491da177e4SLinus Torvalds { 35501da177e4SLinus Torvalds struct dentry *dentry; 3551dae6ad8fSAl Viro struct path path; 3552dae6ad8fSAl Viro int error; 3553972567f1SJeff Layton unsigned int lookup_flags = 0; 35541da177e4SLinus Torvalds 35558e4bfca1SAl Viro error = may_mknod(mode); 35568e4bfca1SAl Viro if (error) 35578e4bfca1SAl Viro return error; 3558972567f1SJeff Layton retry: 3559972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3560dae6ad8fSAl Viro if (IS_ERR(dentry)) 3561dae6ad8fSAl Viro return PTR_ERR(dentry); 35622ad94ae6SAl Viro 3563dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3564ce3b0f8dSAl Viro mode &= ~current_umask(); 3565dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3566be6d3e56SKentaro Takeda if (error) 3567a8104a9fSAl Viro goto out; 35681da177e4SLinus Torvalds switch (mode & S_IFMT) { 35691da177e4SLinus Torvalds case 0: case S_IFREG: 3570312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 35711da177e4SLinus Torvalds break; 35721da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3573dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 35741da177e4SLinus Torvalds new_decode_dev(dev)); 35751da177e4SLinus Torvalds break; 35761da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3577dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 35781da177e4SLinus Torvalds break; 35791da177e4SLinus Torvalds } 3580a8104a9fSAl Viro out: 3581921a1650SAl Viro done_path_create(&path, dentry); 3582972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3583972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3584972567f1SJeff Layton goto retry; 3585972567f1SJeff Layton } 35861da177e4SLinus Torvalds return error; 35871da177e4SLinus Torvalds } 35881da177e4SLinus Torvalds 35898208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 35905590ff0dSUlrich Drepper { 35915590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 35925590ff0dSUlrich Drepper } 35935590ff0dSUlrich Drepper 359418bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 35951da177e4SLinus Torvalds { 3596a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35978de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 35981da177e4SLinus Torvalds 35991da177e4SLinus Torvalds if (error) 36001da177e4SLinus Torvalds return error; 36011da177e4SLinus Torvalds 3602acfa4380SAl Viro if (!dir->i_op->mkdir) 36031da177e4SLinus Torvalds return -EPERM; 36041da177e4SLinus Torvalds 36051da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 36061da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 36071da177e4SLinus Torvalds if (error) 36081da177e4SLinus Torvalds return error; 36091da177e4SLinus Torvalds 36108de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 36118de52778SAl Viro return -EMLINK; 36128de52778SAl Viro 36131da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3614a74574aaSStephen Smalley if (!error) 3615f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 36161da177e4SLinus Torvalds return error; 36171da177e4SLinus Torvalds } 36184d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 36191da177e4SLinus Torvalds 3620a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 36211da177e4SLinus Torvalds { 36226902d925SDave Hansen struct dentry *dentry; 3623dae6ad8fSAl Viro struct path path; 3624dae6ad8fSAl Viro int error; 3625b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 36261da177e4SLinus Torvalds 3627b76d8b82SJeff Layton retry: 3628b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 36296902d925SDave Hansen if (IS_ERR(dentry)) 3630dae6ad8fSAl Viro return PTR_ERR(dentry); 36316902d925SDave Hansen 3632dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3633ce3b0f8dSAl Viro mode &= ~current_umask(); 3634dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3635a8104a9fSAl Viro if (!error) 3636dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3637921a1650SAl Viro done_path_create(&path, dentry); 3638b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3639b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3640b76d8b82SJeff Layton goto retry; 3641b76d8b82SJeff Layton } 36421da177e4SLinus Torvalds return error; 36431da177e4SLinus Torvalds } 36441da177e4SLinus Torvalds 3645a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 36465590ff0dSUlrich Drepper { 36475590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 36485590ff0dSUlrich Drepper } 36495590ff0dSUlrich Drepper 36501da177e4SLinus Torvalds /* 3651a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3652c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3653a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3654a71905f0SSage Weil * then we drop the dentry now. 36551da177e4SLinus Torvalds * 36561da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 36571da177e4SLinus Torvalds * do a 36581da177e4SLinus Torvalds * 36591da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 36601da177e4SLinus Torvalds * return -EBUSY; 36611da177e4SLinus Torvalds * 36621da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 36631da177e4SLinus Torvalds * that is still in use by something else.. 36641da177e4SLinus Torvalds */ 36651da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 36661da177e4SLinus Torvalds { 36671da177e4SLinus Torvalds shrink_dcache_parent(dentry); 36681da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 366998474236SWaiman Long if (dentry->d_lockref.count == 1) 36701da177e4SLinus Torvalds __d_drop(dentry); 36711da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 36721da177e4SLinus Torvalds } 36734d359507SAl Viro EXPORT_SYMBOL(dentry_unhash); 36741da177e4SLinus Torvalds 36751da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 36761da177e4SLinus Torvalds { 36771da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 36781da177e4SLinus Torvalds 36791da177e4SLinus Torvalds if (error) 36801da177e4SLinus Torvalds return error; 36811da177e4SLinus Torvalds 3682acfa4380SAl Viro if (!dir->i_op->rmdir) 36831da177e4SLinus Torvalds return -EPERM; 36841da177e4SLinus Torvalds 36851d2ef590SAl Viro dget(dentry); 36861b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3687912dbc15SSage Weil 36881da177e4SLinus Torvalds error = -EBUSY; 36897af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3690912dbc15SSage Weil goto out; 3691912dbc15SSage Weil 36921da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3693912dbc15SSage Weil if (error) 3694912dbc15SSage Weil goto out; 3695912dbc15SSage Weil 36963cebde24SSage Weil shrink_dcache_parent(dentry); 36971da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3698912dbc15SSage Weil if (error) 3699912dbc15SSage Weil goto out; 3700912dbc15SSage Weil 37011da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3702d83c49f3SAl Viro dont_mount(dentry); 37038ed936b5SEric W. Biederman detach_mounts(dentry); 37041da177e4SLinus Torvalds 3705912dbc15SSage Weil out: 3706912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 37071d2ef590SAl Viro dput(dentry); 3708912dbc15SSage Weil if (!error) 3709912dbc15SSage Weil d_delete(dentry); 37101da177e4SLinus Torvalds return error; 37111da177e4SLinus Torvalds } 37124d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 37131da177e4SLinus Torvalds 37145590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 37151da177e4SLinus Torvalds { 37161da177e4SLinus Torvalds int error = 0; 371791a27b2aSJeff Layton struct filename *name; 37181da177e4SLinus Torvalds struct dentry *dentry; 3719f5beed75SAl Viro struct path path; 3720f5beed75SAl Viro struct qstr last; 3721f5beed75SAl Viro int type; 3722c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3723c6ee9206SJeff Layton retry: 3724f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3725f5beed75SAl Viro &path, &last, &type, lookup_flags); 372691a27b2aSJeff Layton if (IS_ERR(name)) 372791a27b2aSJeff Layton return PTR_ERR(name); 37281da177e4SLinus Torvalds 3729f5beed75SAl Viro switch (type) { 37301da177e4SLinus Torvalds case LAST_DOTDOT: 37311da177e4SLinus Torvalds error = -ENOTEMPTY; 37321da177e4SLinus Torvalds goto exit1; 37331da177e4SLinus Torvalds case LAST_DOT: 37341da177e4SLinus Torvalds error = -EINVAL; 37351da177e4SLinus Torvalds goto exit1; 37361da177e4SLinus Torvalds case LAST_ROOT: 37371da177e4SLinus Torvalds error = -EBUSY; 37381da177e4SLinus Torvalds goto exit1; 37391da177e4SLinus Torvalds } 37400612d9fbSOGAWA Hirofumi 3741f5beed75SAl Viro error = mnt_want_write(path.mnt); 3742c30dabfeSJan Kara if (error) 3743c30dabfeSJan Kara goto exit1; 37440612d9fbSOGAWA Hirofumi 3745f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3746f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 37471da177e4SLinus Torvalds error = PTR_ERR(dentry); 37486902d925SDave Hansen if (IS_ERR(dentry)) 37496902d925SDave Hansen goto exit2; 3750e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3751e6bc45d6STheodore Ts'o error = -ENOENT; 3752e6bc45d6STheodore Ts'o goto exit3; 3753e6bc45d6STheodore Ts'o } 3754f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3755be6d3e56SKentaro Takeda if (error) 3756c30dabfeSJan Kara goto exit3; 3757f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 37580622753bSDave Hansen exit3: 37591da177e4SLinus Torvalds dput(dentry); 37606902d925SDave Hansen exit2: 3761f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 3762f5beed75SAl Viro mnt_drop_write(path.mnt); 37631da177e4SLinus Torvalds exit1: 3764f5beed75SAl Viro path_put(&path); 37651da177e4SLinus Torvalds putname(name); 3766c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3767c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3768c6ee9206SJeff Layton goto retry; 3769c6ee9206SJeff Layton } 37701da177e4SLinus Torvalds return error; 37711da177e4SLinus Torvalds } 37721da177e4SLinus Torvalds 37733cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 37745590ff0dSUlrich Drepper { 37755590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 37765590ff0dSUlrich Drepper } 37775590ff0dSUlrich Drepper 3778b21996e3SJ. Bruce Fields /** 3779b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3780b21996e3SJ. Bruce Fields * @dir: parent directory 3781b21996e3SJ. Bruce Fields * @dentry: victim 3782b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3783b21996e3SJ. Bruce Fields * 3784b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3785b21996e3SJ. Bruce Fields * 3786b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3787b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3788b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3789b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3790b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3791b21996e3SJ. Bruce Fields * 3792b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3793b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3794b21996e3SJ. Bruce Fields * to be NFS exported. 3795b21996e3SJ. Bruce Fields */ 3796b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 37971da177e4SLinus Torvalds { 37989accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 37991da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 38001da177e4SLinus Torvalds 38011da177e4SLinus Torvalds if (error) 38021da177e4SLinus Torvalds return error; 38031da177e4SLinus Torvalds 3804acfa4380SAl Viro if (!dir->i_op->unlink) 38051da177e4SLinus Torvalds return -EPERM; 38061da177e4SLinus Torvalds 38079accbb97SJ. Bruce Fields mutex_lock(&target->i_mutex); 38088ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 38091da177e4SLinus Torvalds error = -EBUSY; 38101da177e4SLinus Torvalds else { 38111da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3812bec1052eSAl Viro if (!error) { 38135a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 38145a14696cSJ. Bruce Fields if (error) 3815b21996e3SJ. Bruce Fields goto out; 38161da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 38178ed936b5SEric W. Biederman if (!error) { 3818d83c49f3SAl Viro dont_mount(dentry); 38198ed936b5SEric W. Biederman detach_mounts(dentry); 38208ed936b5SEric W. Biederman } 3821bec1052eSAl Viro } 38221da177e4SLinus Torvalds } 3823b21996e3SJ. Bruce Fields out: 38249accbb97SJ. Bruce Fields mutex_unlock(&target->i_mutex); 38251da177e4SLinus Torvalds 38261da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 38271da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 38289accbb97SJ. Bruce Fields fsnotify_link_count(target); 38291da177e4SLinus Torvalds d_delete(dentry); 38301da177e4SLinus Torvalds } 38310eeca283SRobert Love 38321da177e4SLinus Torvalds return error; 38331da177e4SLinus Torvalds } 38344d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 38351da177e4SLinus Torvalds 38361da177e4SLinus Torvalds /* 38371da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 38381b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 38391da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 38401da177e4SLinus Torvalds * while waiting on the I/O. 38411da177e4SLinus Torvalds */ 38425590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 38431da177e4SLinus Torvalds { 38442ad94ae6SAl Viro int error; 384591a27b2aSJeff Layton struct filename *name; 38461da177e4SLinus Torvalds struct dentry *dentry; 3847f5beed75SAl Viro struct path path; 3848f5beed75SAl Viro struct qstr last; 3849f5beed75SAl Viro int type; 38501da177e4SLinus Torvalds struct inode *inode = NULL; 3851b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 38525d18f813SJeff Layton unsigned int lookup_flags = 0; 38535d18f813SJeff Layton retry: 3854f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3855f5beed75SAl Viro &path, &last, &type, lookup_flags); 385691a27b2aSJeff Layton if (IS_ERR(name)) 385791a27b2aSJeff Layton return PTR_ERR(name); 38582ad94ae6SAl Viro 38591da177e4SLinus Torvalds error = -EISDIR; 3860f5beed75SAl Viro if (type != LAST_NORM) 38611da177e4SLinus Torvalds goto exit1; 38620612d9fbSOGAWA Hirofumi 3863f5beed75SAl Viro error = mnt_want_write(path.mnt); 3864c30dabfeSJan Kara if (error) 3865c30dabfeSJan Kara goto exit1; 3866b21996e3SJ. Bruce Fields retry_deleg: 3867f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3868f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38691da177e4SLinus Torvalds error = PTR_ERR(dentry); 38701da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 38711da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3872f5beed75SAl Viro if (last.name[last.len]) 387350338b88STörök Edwin goto slashes; 38741da177e4SLinus Torvalds inode = dentry->d_inode; 3875b18825a7SDavid Howells if (d_is_negative(dentry)) 3876e6bc45d6STheodore Ts'o goto slashes; 38777de9c6eeSAl Viro ihold(inode); 3878f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3879be6d3e56SKentaro Takeda if (error) 3880c30dabfeSJan Kara goto exit2; 3881f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 38821da177e4SLinus Torvalds exit2: 38831da177e4SLinus Torvalds dput(dentry); 38841da177e4SLinus Torvalds } 3885f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 38861da177e4SLinus Torvalds if (inode) 38871da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3888b21996e3SJ. Bruce Fields inode = NULL; 3889b21996e3SJ. Bruce Fields if (delegated_inode) { 38905a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3891b21996e3SJ. Bruce Fields if (!error) 3892b21996e3SJ. Bruce Fields goto retry_deleg; 3893b21996e3SJ. Bruce Fields } 3894f5beed75SAl Viro mnt_drop_write(path.mnt); 38951da177e4SLinus Torvalds exit1: 3896f5beed75SAl Viro path_put(&path); 38971da177e4SLinus Torvalds putname(name); 38985d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 38995d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 39005d18f813SJeff Layton inode = NULL; 39015d18f813SJeff Layton goto retry; 39025d18f813SJeff Layton } 39031da177e4SLinus Torvalds return error; 39041da177e4SLinus Torvalds 39051da177e4SLinus Torvalds slashes: 3906b18825a7SDavid Howells if (d_is_negative(dentry)) 3907b18825a7SDavid Howells error = -ENOENT; 390844b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3909b18825a7SDavid Howells error = -EISDIR; 3910b18825a7SDavid Howells else 3911b18825a7SDavid Howells error = -ENOTDIR; 39121da177e4SLinus Torvalds goto exit2; 39131da177e4SLinus Torvalds } 39141da177e4SLinus Torvalds 39152e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 39165590ff0dSUlrich Drepper { 39175590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 39185590ff0dSUlrich Drepper return -EINVAL; 39195590ff0dSUlrich Drepper 39205590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 39215590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 39225590ff0dSUlrich Drepper 39235590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 39245590ff0dSUlrich Drepper } 39255590ff0dSUlrich Drepper 39263480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 39275590ff0dSUlrich Drepper { 39285590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 39295590ff0dSUlrich Drepper } 39305590ff0dSUlrich Drepper 3931db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 39321da177e4SLinus Torvalds { 3933a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 39341da177e4SLinus Torvalds 39351da177e4SLinus Torvalds if (error) 39361da177e4SLinus Torvalds return error; 39371da177e4SLinus Torvalds 3938acfa4380SAl Viro if (!dir->i_op->symlink) 39391da177e4SLinus Torvalds return -EPERM; 39401da177e4SLinus Torvalds 39411da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 39421da177e4SLinus Torvalds if (error) 39431da177e4SLinus Torvalds return error; 39441da177e4SLinus Torvalds 39451da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3946a74574aaSStephen Smalley if (!error) 3947f38aa942SAmy Griffis fsnotify_create(dir, dentry); 39481da177e4SLinus Torvalds return error; 39491da177e4SLinus Torvalds } 39504d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 39511da177e4SLinus Torvalds 39522e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 39532e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 39541da177e4SLinus Torvalds { 39552ad94ae6SAl Viro int error; 395691a27b2aSJeff Layton struct filename *from; 39576902d925SDave Hansen struct dentry *dentry; 3958dae6ad8fSAl Viro struct path path; 3959f46d3567SJeff Layton unsigned int lookup_flags = 0; 39601da177e4SLinus Torvalds 39611da177e4SLinus Torvalds from = getname(oldname); 39621da177e4SLinus Torvalds if (IS_ERR(from)) 39631da177e4SLinus Torvalds return PTR_ERR(from); 3964f46d3567SJeff Layton retry: 3965f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 39661da177e4SLinus Torvalds error = PTR_ERR(dentry); 39676902d925SDave Hansen if (IS_ERR(dentry)) 3968dae6ad8fSAl Viro goto out_putname; 39696902d925SDave Hansen 397091a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3971a8104a9fSAl Viro if (!error) 397291a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3973921a1650SAl Viro done_path_create(&path, dentry); 3974f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 3975f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 3976f46d3567SJeff Layton goto retry; 3977f46d3567SJeff Layton } 39786902d925SDave Hansen out_putname: 39791da177e4SLinus Torvalds putname(from); 39801da177e4SLinus Torvalds return error; 39811da177e4SLinus Torvalds } 39821da177e4SLinus Torvalds 39833480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 39845590ff0dSUlrich Drepper { 39855590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 39865590ff0dSUlrich Drepper } 39875590ff0dSUlrich Drepper 3988146a8595SJ. Bruce Fields /** 3989146a8595SJ. Bruce Fields * vfs_link - create a new link 3990146a8595SJ. Bruce Fields * @old_dentry: object to be linked 3991146a8595SJ. Bruce Fields * @dir: new parent 3992146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 3993146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 3994146a8595SJ. Bruce Fields * 3995146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 3996146a8595SJ. Bruce Fields * 3997146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 3998146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 3999146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4000146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4001146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4002146a8595SJ. Bruce Fields * 4003146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4004146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4005146a8595SJ. Bruce Fields * to be NFS exported. 4006146a8595SJ. Bruce Fields */ 4007146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 40081da177e4SLinus Torvalds { 40091da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 40108de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 40111da177e4SLinus Torvalds int error; 40121da177e4SLinus Torvalds 40131da177e4SLinus Torvalds if (!inode) 40141da177e4SLinus Torvalds return -ENOENT; 40151da177e4SLinus Torvalds 4016a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 40171da177e4SLinus Torvalds if (error) 40181da177e4SLinus Torvalds return error; 40191da177e4SLinus Torvalds 40201da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 40211da177e4SLinus Torvalds return -EXDEV; 40221da177e4SLinus Torvalds 40231da177e4SLinus Torvalds /* 40241da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 40251da177e4SLinus Torvalds */ 40261da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 40271da177e4SLinus Torvalds return -EPERM; 4028acfa4380SAl Viro if (!dir->i_op->link) 40291da177e4SLinus Torvalds return -EPERM; 40307e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 40311da177e4SLinus Torvalds return -EPERM; 40321da177e4SLinus Torvalds 40331da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 40341da177e4SLinus Torvalds if (error) 40351da177e4SLinus Torvalds return error; 40361da177e4SLinus Torvalds 40377e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 4038aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4039f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4040aae8a97dSAneesh Kumar K.V error = -ENOENT; 40418de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 40428de52778SAl Viro error = -EMLINK; 4043146a8595SJ. Bruce Fields else { 4044146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4045146a8595SJ. Bruce Fields if (!error) 40461da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4047146a8595SJ. Bruce Fields } 4048f4e0c30cSAl Viro 4049f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4050f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4051f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4052f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4053f4e0c30cSAl Viro } 40547e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 4055e31e14ecSStephen Smalley if (!error) 40567e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 40571da177e4SLinus Torvalds return error; 40581da177e4SLinus Torvalds } 40594d359507SAl Viro EXPORT_SYMBOL(vfs_link); 40601da177e4SLinus Torvalds 40611da177e4SLinus Torvalds /* 40621da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 40631da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 40641da177e4SLinus Torvalds * newname. --KAB 40651da177e4SLinus Torvalds * 40661da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 40671da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 40681da177e4SLinus Torvalds * and other special files. --ADM 40691da177e4SLinus Torvalds */ 40702e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 40712e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 40721da177e4SLinus Torvalds { 40731da177e4SLinus Torvalds struct dentry *new_dentry; 4074dae6ad8fSAl Viro struct path old_path, new_path; 4075146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 407611a7b371SAneesh Kumar K.V int how = 0; 40771da177e4SLinus Torvalds int error; 40781da177e4SLinus Torvalds 407911a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4080c04030e1SUlrich Drepper return -EINVAL; 408111a7b371SAneesh Kumar K.V /* 4082f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4083f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4084f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 408511a7b371SAneesh Kumar K.V */ 4086f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4087f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4088f0cc6ffbSLinus Torvalds return -ENOENT; 408911a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4090f0cc6ffbSLinus Torvalds } 4091c04030e1SUlrich Drepper 409211a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 409311a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4094442e31caSJeff Layton retry: 409511a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 40961da177e4SLinus Torvalds if (error) 40972ad94ae6SAl Viro return error; 40982ad94ae6SAl Viro 4099442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4100442e31caSJeff Layton (how & LOOKUP_REVAL)); 41011da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 41026902d925SDave Hansen if (IS_ERR(new_dentry)) 4103dae6ad8fSAl Viro goto out; 4104dae6ad8fSAl Viro 4105dae6ad8fSAl Viro error = -EXDEV; 4106dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4107dae6ad8fSAl Viro goto out_dput; 4108800179c9SKees Cook error = may_linkat(&old_path); 4109800179c9SKees Cook if (unlikely(error)) 4110800179c9SKees Cook goto out_dput; 4111dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4112be6d3e56SKentaro Takeda if (error) 4113a8104a9fSAl Viro goto out_dput; 4114146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 411575c3f29dSDave Hansen out_dput: 4116921a1650SAl Viro done_path_create(&new_path, new_dentry); 4117146a8595SJ. Bruce Fields if (delegated_inode) { 4118146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4119d22e6338SOleg Drokin if (!error) { 4120d22e6338SOleg Drokin path_put(&old_path); 4121146a8595SJ. Bruce Fields goto retry; 4122146a8595SJ. Bruce Fields } 4123d22e6338SOleg Drokin } 4124442e31caSJeff Layton if (retry_estale(error, how)) { 4125d22e6338SOleg Drokin path_put(&old_path); 4126442e31caSJeff Layton how |= LOOKUP_REVAL; 4127442e31caSJeff Layton goto retry; 4128442e31caSJeff Layton } 41291da177e4SLinus Torvalds out: 41302d8f3038SAl Viro path_put(&old_path); 41311da177e4SLinus Torvalds 41321da177e4SLinus Torvalds return error; 41331da177e4SLinus Torvalds } 41341da177e4SLinus Torvalds 41353480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 41365590ff0dSUlrich Drepper { 4137c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 41385590ff0dSUlrich Drepper } 41395590ff0dSUlrich Drepper 4140bc27027aSMiklos Szeredi /** 4141bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4142bc27027aSMiklos Szeredi * @old_dir: parent of source 4143bc27027aSMiklos Szeredi * @old_dentry: source 4144bc27027aSMiklos Szeredi * @new_dir: parent of destination 4145bc27027aSMiklos Szeredi * @new_dentry: destination 4146bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4147520c8b16SMiklos Szeredi * @flags: rename flags 4148bc27027aSMiklos Szeredi * 4149bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4150bc27027aSMiklos Szeredi * 4151bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4152bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4153bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4154bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4155bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4156bc27027aSMiklos Szeredi * so. 4157bc27027aSMiklos Szeredi * 4158bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4159bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4160bc27027aSMiklos Szeredi * to be NFS exported. 4161bc27027aSMiklos Szeredi * 41621da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 41631da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 41641da177e4SLinus Torvalds * Problems: 4165d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 41661da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 41671da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4168a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 41691da177e4SLinus Torvalds * story. 41706cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 41716cedba89SJ. Bruce Fields * and source (if it is not a directory). 41721b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 41731da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 41741da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4175a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 41761da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 41771da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 41781da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4179a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 41801da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 41811da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 41821da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4183e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 41841b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 41851da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4186c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 41871da177e4SLinus Torvalds * locking]. 41881da177e4SLinus Torvalds */ 41891da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 41908e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4191520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 41921da177e4SLinus Torvalds { 41931da177e4SLinus Torvalds int error; 4194bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 419559b0df21SEric Paris const unsigned char *old_name; 4196bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4197bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4198da1ce067SMiklos Szeredi bool new_is_dir = false; 4199da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 42001da177e4SLinus Torvalds 4201bc27027aSMiklos Szeredi if (source == target) 42021da177e4SLinus Torvalds return 0; 42031da177e4SLinus Torvalds 42041da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 42051da177e4SLinus Torvalds if (error) 42061da177e4SLinus Torvalds return error; 42071da177e4SLinus Torvalds 4208da1ce067SMiklos Szeredi if (!target) { 4209a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4210da1ce067SMiklos Szeredi } else { 4211da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4212da1ce067SMiklos Szeredi 4213da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 42141da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4215da1ce067SMiklos Szeredi else 4216da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4217da1ce067SMiklos Szeredi } 42181da177e4SLinus Torvalds if (error) 42191da177e4SLinus Torvalds return error; 42201da177e4SLinus Torvalds 42217177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 42221da177e4SLinus Torvalds return -EPERM; 42231da177e4SLinus Torvalds 4224520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4225520c8b16SMiklos Szeredi return -EINVAL; 4226520c8b16SMiklos Szeredi 4227bc27027aSMiklos Szeredi /* 4228bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4229bc27027aSMiklos Szeredi * we'll need to flip '..'. 4230bc27027aSMiklos Szeredi */ 4231da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4232da1ce067SMiklos Szeredi if (is_dir) { 4233bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4234bc27027aSMiklos Szeredi if (error) 4235bc27027aSMiklos Szeredi return error; 4236bc27027aSMiklos Szeredi } 4237da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4238da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4239da1ce067SMiklos Szeredi if (error) 4240da1ce067SMiklos Szeredi return error; 4241da1ce067SMiklos Szeredi } 4242da1ce067SMiklos Szeredi } 42430eeca283SRobert Love 42440b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 42450b3974ebSMiklos Szeredi flags); 4246bc27027aSMiklos Szeredi if (error) 4247bc27027aSMiklos Szeredi return error; 4248bc27027aSMiklos Szeredi 4249bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4250bc27027aSMiklos Szeredi dget(new_dentry); 4251da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4252bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4253bc27027aSMiklos Szeredi else if (target) 4254bc27027aSMiklos Szeredi mutex_lock(&target->i_mutex); 4255bc27027aSMiklos Szeredi 4256bc27027aSMiklos Szeredi error = -EBUSY; 42577af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4258bc27027aSMiklos Szeredi goto out; 4259bc27027aSMiklos Szeredi 4260da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4261bc27027aSMiklos Szeredi error = -EMLINK; 4262da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4263bc27027aSMiklos Szeredi goto out; 4264da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4265da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4266da1ce067SMiklos Szeredi goto out; 4267da1ce067SMiklos Szeredi } 4268da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4269bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4270da1ce067SMiklos Szeredi if (!is_dir) { 4271bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4272bc27027aSMiklos Szeredi if (error) 4273bc27027aSMiklos Szeredi goto out; 4274da1ce067SMiklos Szeredi } 4275da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4276bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4277bc27027aSMiklos Szeredi if (error) 4278bc27027aSMiklos Szeredi goto out; 4279bc27027aSMiklos Szeredi } 42807177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4281520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4282520c8b16SMiklos Szeredi new_dir, new_dentry); 4283520c8b16SMiklos Szeredi } else { 42847177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4285520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4286520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4287520c8b16SMiklos Szeredi } 4288bc27027aSMiklos Szeredi if (error) 4289bc27027aSMiklos Szeredi goto out; 4290bc27027aSMiklos Szeredi 4291da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 42921da177e4SLinus Torvalds if (is_dir) 4293bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4294bc27027aSMiklos Szeredi dont_mount(new_dentry); 42958ed936b5SEric W. Biederman detach_mounts(new_dentry); 4296bc27027aSMiklos Szeredi } 4297da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4298da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4299bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4300da1ce067SMiklos Szeredi else 4301da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4302da1ce067SMiklos Szeredi } 4303bc27027aSMiklos Szeredi out: 4304da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4305bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4306bc27027aSMiklos Szeredi else if (target) 4307bc27027aSMiklos Szeredi mutex_unlock(&target->i_mutex); 4308bc27027aSMiklos Szeredi dput(new_dentry); 4309da1ce067SMiklos Szeredi if (!error) { 4310123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4311da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4312da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4313da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4314da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4315da1ce067SMiklos Szeredi } 4316da1ce067SMiklos Szeredi } 43170eeca283SRobert Love fsnotify_oldname_free(old_name); 43180eeca283SRobert Love 43191da177e4SLinus Torvalds return error; 43201da177e4SLinus Torvalds } 43214d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 43221da177e4SLinus Torvalds 4323520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4324520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 43251da177e4SLinus Torvalds { 43261da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 43271da177e4SLinus Torvalds struct dentry *trap; 4328f5beed75SAl Viro struct path old_path, new_path; 4329f5beed75SAl Viro struct qstr old_last, new_last; 4330f5beed75SAl Viro int old_type, new_type; 43318e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 433291a27b2aSJeff Layton struct filename *from; 433391a27b2aSJeff Layton struct filename *to; 4334f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4335c6a94284SJeff Layton bool should_retry = false; 43362ad94ae6SAl Viro int error; 4337520c8b16SMiklos Szeredi 43380d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4339da1ce067SMiklos Szeredi return -EINVAL; 4340da1ce067SMiklos Szeredi 43410d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 43420d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4343520c8b16SMiklos Szeredi return -EINVAL; 4344520c8b16SMiklos Szeredi 43450d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 43460d7a8555SMiklos Szeredi return -EPERM; 43470d7a8555SMiklos Szeredi 4348f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4349f5beed75SAl Viro target_flags = 0; 4350f5beed75SAl Viro 4351c6a94284SJeff Layton retry: 4352f5beed75SAl Viro from = user_path_parent(olddfd, oldname, 4353f5beed75SAl Viro &old_path, &old_last, &old_type, lookup_flags); 435491a27b2aSJeff Layton if (IS_ERR(from)) { 435591a27b2aSJeff Layton error = PTR_ERR(from); 43561da177e4SLinus Torvalds goto exit; 435791a27b2aSJeff Layton } 43581da177e4SLinus Torvalds 4359f5beed75SAl Viro to = user_path_parent(newdfd, newname, 4360f5beed75SAl Viro &new_path, &new_last, &new_type, lookup_flags); 436191a27b2aSJeff Layton if (IS_ERR(to)) { 436291a27b2aSJeff Layton error = PTR_ERR(to); 43631da177e4SLinus Torvalds goto exit1; 436491a27b2aSJeff Layton } 43651da177e4SLinus Torvalds 43661da177e4SLinus Torvalds error = -EXDEV; 4367f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 43681da177e4SLinus Torvalds goto exit2; 43691da177e4SLinus Torvalds 43701da177e4SLinus Torvalds error = -EBUSY; 4371f5beed75SAl Viro if (old_type != LAST_NORM) 43721da177e4SLinus Torvalds goto exit2; 43731da177e4SLinus Torvalds 43740a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 43750a7c3937SMiklos Szeredi error = -EEXIST; 4376f5beed75SAl Viro if (new_type != LAST_NORM) 43771da177e4SLinus Torvalds goto exit2; 43781da177e4SLinus Torvalds 4379f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4380c30dabfeSJan Kara if (error) 4381c30dabfeSJan Kara goto exit2; 4382c30dabfeSJan Kara 43838e6d782cSJ. Bruce Fields retry_deleg: 4384f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 43851da177e4SLinus Torvalds 4386f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 43871da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 43881da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 43891da177e4SLinus Torvalds goto exit3; 43901da177e4SLinus Torvalds /* source must exist */ 43911da177e4SLinus Torvalds error = -ENOENT; 4392b18825a7SDavid Howells if (d_is_negative(old_dentry)) 43931da177e4SLinus Torvalds goto exit4; 4394f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 43951da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 43961da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 43971da177e4SLinus Torvalds goto exit4; 43980a7c3937SMiklos Szeredi error = -EEXIST; 43990a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 44000a7c3937SMiklos Szeredi goto exit5; 4401da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4402da1ce067SMiklos Szeredi error = -ENOENT; 4403da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4404da1ce067SMiklos Szeredi goto exit5; 4405da1ce067SMiklos Szeredi 4406da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4407da1ce067SMiklos Szeredi error = -ENOTDIR; 4408f5beed75SAl Viro if (new_last.name[new_last.len]) 4409da1ce067SMiklos Szeredi goto exit5; 4410da1ce067SMiklos Szeredi } 4411da1ce067SMiklos Szeredi } 44120a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 44130a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 44140a7c3937SMiklos Szeredi error = -ENOTDIR; 4415f5beed75SAl Viro if (old_last.name[old_last.len]) 44160a7c3937SMiklos Szeredi goto exit5; 4417f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 44180a7c3937SMiklos Szeredi goto exit5; 44190a7c3937SMiklos Szeredi } 44200a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 44210a7c3937SMiklos Szeredi error = -EINVAL; 44220a7c3937SMiklos Szeredi if (old_dentry == trap) 44230a7c3937SMiklos Szeredi goto exit5; 44241da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4425da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 44261da177e4SLinus Torvalds error = -ENOTEMPTY; 44271da177e4SLinus Torvalds if (new_dentry == trap) 44281da177e4SLinus Torvalds goto exit5; 44291da177e4SLinus Torvalds 4430f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4431f5beed75SAl Viro &new_path, new_dentry, flags); 4432be6d3e56SKentaro Takeda if (error) 4433c30dabfeSJan Kara goto exit5; 4434f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4435f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4436520c8b16SMiklos Szeredi &delegated_inode, flags); 44371da177e4SLinus Torvalds exit5: 44381da177e4SLinus Torvalds dput(new_dentry); 44391da177e4SLinus Torvalds exit4: 44401da177e4SLinus Torvalds dput(old_dentry); 44411da177e4SLinus Torvalds exit3: 4442f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 44438e6d782cSJ. Bruce Fields if (delegated_inode) { 44448e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 44458e6d782cSJ. Bruce Fields if (!error) 44468e6d782cSJ. Bruce Fields goto retry_deleg; 44478e6d782cSJ. Bruce Fields } 4448f5beed75SAl Viro mnt_drop_write(old_path.mnt); 44491da177e4SLinus Torvalds exit2: 4450c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4451c6a94284SJeff Layton should_retry = true; 4452f5beed75SAl Viro path_put(&new_path); 44532ad94ae6SAl Viro putname(to); 44541da177e4SLinus Torvalds exit1: 4455f5beed75SAl Viro path_put(&old_path); 44561da177e4SLinus Torvalds putname(from); 4457c6a94284SJeff Layton if (should_retry) { 4458c6a94284SJeff Layton should_retry = false; 4459c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4460c6a94284SJeff Layton goto retry; 4461c6a94284SJeff Layton } 44622ad94ae6SAl Viro exit: 44631da177e4SLinus Torvalds return error; 44641da177e4SLinus Torvalds } 44651da177e4SLinus Torvalds 4466520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4467520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4468520c8b16SMiklos Szeredi { 4469520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4470520c8b16SMiklos Szeredi } 4471520c8b16SMiklos Szeredi 4472a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 44735590ff0dSUlrich Drepper { 4474520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 44755590ff0dSUlrich Drepper } 44765590ff0dSUlrich Drepper 4477787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4478787fb6bcSMiklos Szeredi { 4479787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4480787fb6bcSMiklos Szeredi if (error) 4481787fb6bcSMiklos Szeredi return error; 4482787fb6bcSMiklos Szeredi 4483787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4484787fb6bcSMiklos Szeredi return -EPERM; 4485787fb6bcSMiklos Szeredi 4486787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4487787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4488787fb6bcSMiklos Szeredi } 4489787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4490787fb6bcSMiklos Szeredi 44915d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 44921da177e4SLinus Torvalds { 44935d826c84SAl Viro int len = PTR_ERR(link); 44941da177e4SLinus Torvalds if (IS_ERR(link)) 44951da177e4SLinus Torvalds goto out; 44961da177e4SLinus Torvalds 44971da177e4SLinus Torvalds len = strlen(link); 44981da177e4SLinus Torvalds if (len > (unsigned) buflen) 44991da177e4SLinus Torvalds len = buflen; 45001da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 45011da177e4SLinus Torvalds len = -EFAULT; 45021da177e4SLinus Torvalds out: 45031da177e4SLinus Torvalds return len; 45041da177e4SLinus Torvalds } 45055d826c84SAl Viro EXPORT_SYMBOL(readlink_copy); 45061da177e4SLinus Torvalds 45071da177e4SLinus Torvalds /* 45081da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 45091da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 45101da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 45111da177e4SLinus Torvalds */ 45121da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 45131da177e4SLinus Torvalds { 4514cc314eefSLinus Torvalds void *cookie; 45155f2c4179SAl Viro struct inode *inode = d_inode(dentry); 45165f2c4179SAl Viro const char *link = inode->i_link; 4517694a1764SMarcin Slusarz int res; 4518cc314eefSLinus Torvalds 4519d4dee48bSAl Viro if (!link) { 45205f2c4179SAl Viro link = inode->i_op->follow_link(dentry, &cookie); 4521680baacbSAl Viro if (IS_ERR(link)) 4522680baacbSAl Viro return PTR_ERR(link); 4523d4dee48bSAl Viro } 4524680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 45255f2c4179SAl Viro if (inode->i_op->put_link) 45265f2c4179SAl Viro inode->i_op->put_link(inode, cookie); 4527694a1764SMarcin Slusarz return res; 45281da177e4SLinus Torvalds } 45294d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 45301da177e4SLinus Torvalds 45311da177e4SLinus Torvalds /* get the link contents into pagecache */ 45321da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 45331da177e4SLinus Torvalds { 4534ebd09abbSDuane Griffin char *kaddr; 45351da177e4SLinus Torvalds struct page *page; 45361da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 4537090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 45381da177e4SLinus Torvalds if (IS_ERR(page)) 45396fe6900eSNick Piggin return (char*)page; 45401da177e4SLinus Torvalds *ppage = page; 4541ebd09abbSDuane Griffin kaddr = kmap(page); 4542ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 4543ebd09abbSDuane Griffin return kaddr; 45441da177e4SLinus Torvalds } 45451da177e4SLinus Torvalds 45461da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 45471da177e4SLinus Torvalds { 45481da177e4SLinus Torvalds struct page *page = NULL; 45495d826c84SAl Viro int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); 45501da177e4SLinus Torvalds if (page) { 45511da177e4SLinus Torvalds kunmap(page); 45521da177e4SLinus Torvalds page_cache_release(page); 45531da177e4SLinus Torvalds } 45541da177e4SLinus Torvalds return res; 45551da177e4SLinus Torvalds } 45564d359507SAl Viro EXPORT_SYMBOL(page_readlink); 45571da177e4SLinus Torvalds 45586e77137bSAl Viro const char *page_follow_link_light(struct dentry *dentry, void **cookie) 45591da177e4SLinus Torvalds { 4560cc314eefSLinus Torvalds struct page *page = NULL; 4561680baacbSAl Viro char *res = page_getlink(dentry, &page); 4562680baacbSAl Viro if (!IS_ERR(res)) 4563680baacbSAl Viro *cookie = page; 4564680baacbSAl Viro return res; 45651da177e4SLinus Torvalds } 45664d359507SAl Viro EXPORT_SYMBOL(page_follow_link_light); 45671da177e4SLinus Torvalds 45685f2c4179SAl Viro void page_put_link(struct inode *unused, void *cookie) 45691da177e4SLinus Torvalds { 4570cc314eefSLinus Torvalds struct page *page = cookie; 45711da177e4SLinus Torvalds kunmap(page); 45721da177e4SLinus Torvalds page_cache_release(page); 45731da177e4SLinus Torvalds } 45744d359507SAl Viro EXPORT_SYMBOL(page_put_link); 45751da177e4SLinus Torvalds 457654566b2cSNick Piggin /* 457754566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 457854566b2cSNick Piggin */ 457954566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 45801da177e4SLinus Torvalds { 45811da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 45820adb25d2SKirill Korotaev struct page *page; 4583afddba49SNick Piggin void *fsdata; 4584beb497abSDmitriy Monakhov int err; 45851da177e4SLinus Torvalds char *kaddr; 458654566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 458754566b2cSNick Piggin if (nofs) 458854566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 45891da177e4SLinus Torvalds 45907e53cac4SNeilBrown retry: 4591afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 459254566b2cSNick Piggin flags, &page, &fsdata); 45931da177e4SLinus Torvalds if (err) 4594afddba49SNick Piggin goto fail; 4595afddba49SNick Piggin 4596e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 45971da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 4598e8e3c3d6SCong Wang kunmap_atomic(kaddr); 4599afddba49SNick Piggin 4600afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4601afddba49SNick Piggin page, fsdata); 46021da177e4SLinus Torvalds if (err < 0) 46031da177e4SLinus Torvalds goto fail; 4604afddba49SNick Piggin if (err < len-1) 4605afddba49SNick Piggin goto retry; 4606afddba49SNick Piggin 46071da177e4SLinus Torvalds mark_inode_dirty(inode); 46081da177e4SLinus Torvalds return 0; 46091da177e4SLinus Torvalds fail: 46101da177e4SLinus Torvalds return err; 46111da177e4SLinus Torvalds } 46124d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 46131da177e4SLinus Torvalds 46140adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 46150adb25d2SKirill Korotaev { 46160adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 461754566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 46180adb25d2SKirill Korotaev } 46194d359507SAl Viro EXPORT_SYMBOL(page_symlink); 46200adb25d2SKirill Korotaev 462192e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 46221da177e4SLinus Torvalds .readlink = generic_readlink, 46231da177e4SLinus Torvalds .follow_link = page_follow_link_light, 46241da177e4SLinus Torvalds .put_link = page_put_link, 46251da177e4SLinus Torvalds }; 46261da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4627