11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namei.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Some corrections by tytso. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 121da177e4SLinus Torvalds * lookup logic. 131da177e4SLinus Torvalds */ 141da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 151da177e4SLinus Torvalds */ 161da177e4SLinus Torvalds 171da177e4SLinus Torvalds #include <linux/init.h> 18630d9c47SPaul Gortmaker #include <linux/export.h> 1944696908SDavid S. Miller #include <linux/kernel.h> 201da177e4SLinus Torvalds #include <linux/slab.h> 211da177e4SLinus Torvalds #include <linux/fs.h> 221da177e4SLinus Torvalds #include <linux/namei.h> 231da177e4SLinus Torvalds #include <linux/pagemap.h> 240eeca283SRobert Love #include <linux/fsnotify.h> 251da177e4SLinus Torvalds #include <linux/personality.h> 261da177e4SLinus Torvalds #include <linux/security.h> 276146f0d5SMimi Zohar #include <linux/ima.h> 281da177e4SLinus Torvalds #include <linux/syscalls.h> 291da177e4SLinus Torvalds #include <linux/mount.h> 301da177e4SLinus Torvalds #include <linux/audit.h> 3116f7e0feSRandy Dunlap #include <linux/capability.h> 32834f2a4aSTrond Myklebust #include <linux/file.h> 335590ff0dSUlrich Drepper #include <linux/fcntl.h> 3408ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 355ad4e53bSAl Viro #include <linux/fs_struct.h> 36e77819e5SLinus Torvalds #include <linux/posix_acl.h> 3799d263d4SLinus Torvalds #include <linux/hash.h> 381da177e4SLinus Torvalds #include <asm/uaccess.h> 391da177e4SLinus Torvalds 40e81e3f4dSEric Paris #include "internal.h" 41c7105365SAl Viro #include "mount.h" 42e81e3f4dSEric Paris 431da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 441da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 451da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 461da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 471da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 481da177e4SLinus Torvalds * 491da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 501da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 511da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 521da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 531da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 541da177e4SLinus Torvalds * the special cases of the former code. 551da177e4SLinus Torvalds * 561da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 571da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 581da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 591da177e4SLinus Torvalds * 601da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 611da177e4SLinus Torvalds * resolution to correspond with current state of the code. 621da177e4SLinus Torvalds * 631da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 641da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 651da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 661da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 671da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 681da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 691da177e4SLinus Torvalds */ 701da177e4SLinus Torvalds 711da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 721da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 731da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 741da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 751da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 761da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7725985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 781da177e4SLinus Torvalds * 791da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 801da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 811da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 821da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 831da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 841da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 851da177e4SLinus Torvalds * and in the old Linux semantics. 861da177e4SLinus Torvalds */ 871da177e4SLinus Torvalds 881da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 891da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 901da177e4SLinus Torvalds * 911da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 921da177e4SLinus Torvalds */ 931da177e4SLinus Torvalds 941da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 951da177e4SLinus Torvalds * inside the path - always follow. 961da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 971da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 981da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 991da177e4SLinus Torvalds * otherwise - don't follow. 1001da177e4SLinus Torvalds * (applied in that order). 1011da177e4SLinus Torvalds * 1021da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1031da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1041da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1051da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1061da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1071da177e4SLinus Torvalds */ 1081da177e4SLinus Torvalds /* 1091da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 110a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1111da177e4SLinus Torvalds * any extra contention... 1121da177e4SLinus Torvalds */ 1131da177e4SLinus Torvalds 1141da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1151da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1161da177e4SLinus Torvalds * kernel data space before using them.. 1171da177e4SLinus Torvalds * 1181da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1191da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1201da177e4SLinus Torvalds */ 1217950e385SJeff Layton 122fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12391a27b2aSJeff Layton 12451f39a1fSDavid Drysdale struct filename * 12591a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12691a27b2aSJeff Layton { 12794b5d262SAl Viro struct filename *result; 1287950e385SJeff Layton char *kname; 12994b5d262SAl Viro int len; 1301da177e4SLinus Torvalds 1317ac86265SJeff Layton result = audit_reusename(filename); 1327ac86265SJeff Layton if (result) 1337ac86265SJeff Layton return result; 1347ac86265SJeff Layton 1357950e385SJeff Layton result = __getname(); 1363f9f0aa6SLinus Torvalds if (unlikely(!result)) 1374043cde8SEric Paris return ERR_PTR(-ENOMEM); 1381da177e4SLinus Torvalds 1397950e385SJeff Layton /* 1407950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1417950e385SJeff Layton * allocation 1427950e385SJeff Layton */ 143fd2f7cb5SAl Viro kname = (char *)result->iname; 14491a27b2aSJeff Layton result->name = kname; 1457950e385SJeff Layton 14694b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 14791a27b2aSJeff Layton if (unlikely(len < 0)) { 14894b5d262SAl Viro __putname(result); 14994b5d262SAl Viro return ERR_PTR(len); 15091a27b2aSJeff Layton } 1513f9f0aa6SLinus Torvalds 1527950e385SJeff Layton /* 1537950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1547950e385SJeff Layton * separate struct filename so we can dedicate the entire 1557950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1567950e385SJeff Layton * userland. 1577950e385SJeff Layton */ 15894b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 159fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1607950e385SJeff Layton kname = (char *)result; 1617950e385SJeff Layton 162fd2f7cb5SAl Viro /* 163fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 164fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 165fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 166fd2f7cb5SAl Viro */ 167fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 16894b5d262SAl Viro if (unlikely(!result)) { 16994b5d262SAl Viro __putname(kname); 17094b5d262SAl Viro return ERR_PTR(-ENOMEM); 1717950e385SJeff Layton } 1727950e385SJeff Layton result->name = kname; 17394b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17494b5d262SAl Viro if (unlikely(len < 0)) { 17594b5d262SAl Viro __putname(kname); 17694b5d262SAl Viro kfree(result); 17794b5d262SAl Viro return ERR_PTR(len); 17894b5d262SAl Viro } 17994b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18094b5d262SAl Viro __putname(kname); 18194b5d262SAl Viro kfree(result); 18294b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18394b5d262SAl Viro } 1847950e385SJeff Layton } 1857950e385SJeff Layton 18694b5d262SAl Viro result->refcnt = 1; 1873f9f0aa6SLinus Torvalds /* The empty path is special. */ 1883f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1893f9f0aa6SLinus Torvalds if (empty) 1901fa1e7f6SAndy Whitcroft *empty = 1; 19194b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19294b5d262SAl Viro putname(result); 19394b5d262SAl Viro return ERR_PTR(-ENOENT); 1941da177e4SLinus Torvalds } 19594b5d262SAl Viro } 1967950e385SJeff Layton 1977950e385SJeff Layton result->uptr = filename; 198c4ad8f98SLinus Torvalds result->aname = NULL; 1991da177e4SLinus Torvalds audit_getname(result); 2001da177e4SLinus Torvalds return result; 2013f9f0aa6SLinus Torvalds } 2023f9f0aa6SLinus Torvalds 20391a27b2aSJeff Layton struct filename * 20491a27b2aSJeff Layton getname(const char __user * filename) 205f52e0c11SAl Viro { 206f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 207f52e0c11SAl Viro } 208f52e0c11SAl Viro 209c4ad8f98SLinus Torvalds struct filename * 210c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 211c4ad8f98SLinus Torvalds { 212c4ad8f98SLinus Torvalds struct filename *result; 21308518549SPaul Moore int len = strlen(filename) + 1; 214c4ad8f98SLinus Torvalds 215c4ad8f98SLinus Torvalds result = __getname(); 216c4ad8f98SLinus Torvalds if (unlikely(!result)) 217c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 218c4ad8f98SLinus Torvalds 21908518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 220fd2f7cb5SAl Viro result->name = (char *)result->iname; 22108518549SPaul Moore } else if (len <= PATH_MAX) { 22208518549SPaul Moore struct filename *tmp; 22308518549SPaul Moore 22408518549SPaul Moore tmp = kmalloc(sizeof(*tmp), GFP_KERNEL); 22508518549SPaul Moore if (unlikely(!tmp)) { 22608518549SPaul Moore __putname(result); 22708518549SPaul Moore return ERR_PTR(-ENOMEM); 22808518549SPaul Moore } 22908518549SPaul Moore tmp->name = (char *)result; 23008518549SPaul Moore result = tmp; 23108518549SPaul Moore } else { 23208518549SPaul Moore __putname(result); 23308518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23408518549SPaul Moore } 23508518549SPaul Moore memcpy((char *)result->name, filename, len); 236c4ad8f98SLinus Torvalds result->uptr = NULL; 237c4ad8f98SLinus Torvalds result->aname = NULL; 23855422d0bSPaul Moore result->refcnt = 1; 239fd3522fdSPaul Moore audit_getname(result); 240c4ad8f98SLinus Torvalds 241c4ad8f98SLinus Torvalds return result; 242c4ad8f98SLinus Torvalds } 243c4ad8f98SLinus Torvalds 24491a27b2aSJeff Layton void putname(struct filename *name) 2451da177e4SLinus Torvalds { 24655422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 24755422d0bSPaul Moore 24855422d0bSPaul Moore if (--name->refcnt > 0) 24955422d0bSPaul Moore return; 25055422d0bSPaul Moore 251fd2f7cb5SAl Viro if (name->name != name->iname) { 25255422d0bSPaul Moore __putname(name->name); 25355422d0bSPaul Moore kfree(name); 25455422d0bSPaul Moore } else 25555422d0bSPaul Moore __putname(name); 2561da177e4SLinus Torvalds } 2571da177e4SLinus Torvalds 258e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 259e77819e5SLinus Torvalds { 26084635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 261e77819e5SLinus Torvalds struct posix_acl *acl; 262e77819e5SLinus Torvalds 263e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2643567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2653567866bSAl Viro if (!acl) 266e77819e5SLinus Torvalds return -EAGAIN; 2673567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 2683567866bSAl Viro if (acl == ACL_NOT_CACHED) 269e77819e5SLinus Torvalds return -ECHILD; 270206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 271e77819e5SLinus Torvalds } 272e77819e5SLinus Torvalds 2732982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2744e34e719SChristoph Hellwig if (IS_ERR(acl)) 2754e34e719SChristoph Hellwig return PTR_ERR(acl); 276e77819e5SLinus Torvalds if (acl) { 277e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 278e77819e5SLinus Torvalds posix_acl_release(acl); 279e77819e5SLinus Torvalds return error; 280e77819e5SLinus Torvalds } 28184635d68SLinus Torvalds #endif 282e77819e5SLinus Torvalds 283e77819e5SLinus Torvalds return -EAGAIN; 284e77819e5SLinus Torvalds } 285e77819e5SLinus Torvalds 2865909ccaaSLinus Torvalds /* 287948409c7SAndreas Gruenbacher * This does the basic permission checking 2885909ccaaSLinus Torvalds */ 2897e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2905909ccaaSLinus Torvalds { 29126cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2925909ccaaSLinus Torvalds 2938e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2945909ccaaSLinus Torvalds mode >>= 6; 2955909ccaaSLinus Torvalds else { 296e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2977e40145eSAl Viro int error = check_acl(inode, mask); 2985909ccaaSLinus Torvalds if (error != -EAGAIN) 2995909ccaaSLinus Torvalds return error; 3005909ccaaSLinus Torvalds } 3015909ccaaSLinus Torvalds 3025909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3035909ccaaSLinus Torvalds mode >>= 3; 3045909ccaaSLinus Torvalds } 3055909ccaaSLinus Torvalds 3065909ccaaSLinus Torvalds /* 3075909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3085909ccaaSLinus Torvalds */ 3099c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3105909ccaaSLinus Torvalds return 0; 3115909ccaaSLinus Torvalds return -EACCES; 3125909ccaaSLinus Torvalds } 3131da177e4SLinus Torvalds 3141da177e4SLinus Torvalds /** 3151da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3161da177e4SLinus Torvalds * @inode: inode to check access rights for 3178fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3181da177e4SLinus Torvalds * 3191da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3201da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3211da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 322b74c79e9SNick Piggin * are used for other things. 323b74c79e9SNick Piggin * 324b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 325b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 326b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3271da177e4SLinus Torvalds */ 3282830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3291da177e4SLinus Torvalds { 3305909ccaaSLinus Torvalds int ret; 3311da177e4SLinus Torvalds 3321da177e4SLinus Torvalds /* 333948409c7SAndreas Gruenbacher * Do the basic permission checks. 3341da177e4SLinus Torvalds */ 3357e40145eSAl Viro ret = acl_permission_check(inode, mask); 3365909ccaaSLinus Torvalds if (ret != -EACCES) 3375909ccaaSLinus Torvalds return ret; 3381da177e4SLinus Torvalds 339d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 340d594e7ecSAl Viro /* DACs are overridable for directories */ 34123adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 342d594e7ecSAl Viro return 0; 343d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34423adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34523adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 346d594e7ecSAl Viro return 0; 347d594e7ecSAl Viro return -EACCES; 348d594e7ecSAl Viro } 3491da177e4SLinus Torvalds /* 3501da177e4SLinus Torvalds * Read/write DACs are always overridable. 351d594e7ecSAl Viro * Executable DACs are overridable when there is 352d594e7ecSAl Viro * at least one exec bit set. 3531da177e4SLinus Torvalds */ 354d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 35523adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3561da177e4SLinus Torvalds return 0; 3571da177e4SLinus Torvalds 3581da177e4SLinus Torvalds /* 3591da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3601da177e4SLinus Torvalds */ 3617ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 362d594e7ecSAl Viro if (mask == MAY_READ) 36323adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3641da177e4SLinus Torvalds return 0; 3651da177e4SLinus Torvalds 3661da177e4SLinus Torvalds return -EACCES; 3671da177e4SLinus Torvalds } 3684d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3691da177e4SLinus Torvalds 3703ddcd056SLinus Torvalds /* 3713ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3723ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3733ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3743ddcd056SLinus Torvalds * permission function, use the fast case". 3753ddcd056SLinus Torvalds */ 3763ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3773ddcd056SLinus Torvalds { 3783ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3793ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3803ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3813ddcd056SLinus Torvalds 3823ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3833ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3843ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3853ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3863ddcd056SLinus Torvalds } 3873ddcd056SLinus Torvalds return generic_permission(inode, mask); 3883ddcd056SLinus Torvalds } 3893ddcd056SLinus Torvalds 390cb23beb5SChristoph Hellwig /** 3910bdaea90SDavid Howells * __inode_permission - Check for access rights to a given inode 3920bdaea90SDavid Howells * @inode: Inode to check permission on 3930bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 394cb23beb5SChristoph Hellwig * 3950bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. 396948409c7SAndreas Gruenbacher * 397948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 3980bdaea90SDavid Howells * 3990bdaea90SDavid Howells * This does not check for a read-only file system. You probably want 4000bdaea90SDavid Howells * inode_permission(). 401cb23beb5SChristoph Hellwig */ 4020bdaea90SDavid Howells int __inode_permission(struct inode *inode, int mask) 4031da177e4SLinus Torvalds { 404e6305c43SAl Viro int retval; 4051da177e4SLinus Torvalds 4063ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 4071da177e4SLinus Torvalds /* 4081da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 4091da177e4SLinus Torvalds */ 4101da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 4111da177e4SLinus Torvalds return -EACCES; 4121da177e4SLinus Torvalds } 4131da177e4SLinus Torvalds 4143ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 4151da177e4SLinus Torvalds if (retval) 4161da177e4SLinus Torvalds return retval; 4171da177e4SLinus Torvalds 41808ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 41908ce5f16SSerge E. Hallyn if (retval) 42008ce5f16SSerge E. Hallyn return retval; 42108ce5f16SSerge E. Hallyn 422d09ca739SEric Paris return security_inode_permission(inode, mask); 4231da177e4SLinus Torvalds } 424bd5d0856SMiklos Szeredi EXPORT_SYMBOL(__inode_permission); 4251da177e4SLinus Torvalds 426f4d6ff89SAl Viro /** 4270bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 4280bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 42955852635SRandy Dunlap * @inode: Inode to check permission on 4300bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4310bdaea90SDavid Howells * 4320bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4330bdaea90SDavid Howells */ 4340bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4350bdaea90SDavid Howells { 4360bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4370bdaea90SDavid Howells umode_t mode = inode->i_mode; 4380bdaea90SDavid Howells 4390bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 4400bdaea90SDavid Howells if ((sb->s_flags & MS_RDONLY) && 4410bdaea90SDavid Howells (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4420bdaea90SDavid Howells return -EROFS; 4430bdaea90SDavid Howells } 4440bdaea90SDavid Howells return 0; 4450bdaea90SDavid Howells } 4460bdaea90SDavid Howells 4470bdaea90SDavid Howells /** 4480bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4490bdaea90SDavid Howells * @inode: Inode to check permission on 4500bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4510bdaea90SDavid Howells * 4520bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4530bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4540bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4550bdaea90SDavid Howells * 4560bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4570bdaea90SDavid Howells */ 4580bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4590bdaea90SDavid Howells { 4600bdaea90SDavid Howells int retval; 4610bdaea90SDavid Howells 4620bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4630bdaea90SDavid Howells if (retval) 4640bdaea90SDavid Howells return retval; 4650bdaea90SDavid Howells return __inode_permission(inode, mask); 4660bdaea90SDavid Howells } 4674d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4680bdaea90SDavid Howells 4690bdaea90SDavid Howells /** 4705dd784d0SJan Blunck * path_get - get a reference to a path 4715dd784d0SJan Blunck * @path: path to get the reference to 4725dd784d0SJan Blunck * 4735dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4745dd784d0SJan Blunck */ 475dcf787f3SAl Viro void path_get(const struct path *path) 4765dd784d0SJan Blunck { 4775dd784d0SJan Blunck mntget(path->mnt); 4785dd784d0SJan Blunck dget(path->dentry); 4795dd784d0SJan Blunck } 4805dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4815dd784d0SJan Blunck 4825dd784d0SJan Blunck /** 4831d957f9bSJan Blunck * path_put - put a reference to a path 4841d957f9bSJan Blunck * @path: path to put the reference to 4851d957f9bSJan Blunck * 4861d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4871d957f9bSJan Blunck */ 488dcf787f3SAl Viro void path_put(const struct path *path) 4891da177e4SLinus Torvalds { 4901d957f9bSJan Blunck dput(path->dentry); 4911d957f9bSJan Blunck mntput(path->mnt); 4921da177e4SLinus Torvalds } 4931d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4941da177e4SLinus Torvalds 495894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 4961f55a6ecSAl Viro struct nameidata { 4971f55a6ecSAl Viro struct path path; 4981f55a6ecSAl Viro struct qstr last; 4991f55a6ecSAl Viro struct path root; 5001f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 5011f55a6ecSAl Viro unsigned int flags; 5029883d185SAl Viro unsigned seq, m_seq; 5031f55a6ecSAl Viro int last_type; 5041f55a6ecSAl Viro unsigned depth; 505756daf26SNeilBrown int total_link_count; 506697fc6caSAl Viro struct saved { 507697fc6caSAl Viro struct path link; 508697fc6caSAl Viro void *cookie; 509697fc6caSAl Viro const char *name; 510237d8b32SAl Viro struct inode *inode; 5110450b2d1SAl Viro unsigned seq; 512894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5139883d185SAl Viro struct filename *name; 5149883d185SAl Viro struct nameidata *saved; 5159883d185SAl Viro unsigned root_seq; 5169883d185SAl Viro int dfd; 5171f55a6ecSAl Viro }; 5181f55a6ecSAl Viro 5199883d185SAl Viro static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) 520894bc8c4SAl Viro { 521756daf26SNeilBrown struct nameidata *old = current->nameidata; 522756daf26SNeilBrown p->stack = p->internal; 523c8a53ee5SAl Viro p->dfd = dfd; 524c8a53ee5SAl Viro p->name = name; 525756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 5269883d185SAl Viro p->saved = old; 527756daf26SNeilBrown current->nameidata = p; 528894bc8c4SAl Viro } 529894bc8c4SAl Viro 5309883d185SAl Viro static void restore_nameidata(void) 531894bc8c4SAl Viro { 5329883d185SAl Viro struct nameidata *now = current->nameidata, *old = now->saved; 533756daf26SNeilBrown 534756daf26SNeilBrown current->nameidata = old; 535756daf26SNeilBrown if (old) 536756daf26SNeilBrown old->total_link_count = now->total_link_count; 537e1a63bbcSAl Viro if (now->stack != now->internal) 538756daf26SNeilBrown kfree(now->stack); 539894bc8c4SAl Viro } 540894bc8c4SAl Viro 541894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 542894bc8c4SAl Viro { 543bc40aee0SAl Viro struct saved *p; 544bc40aee0SAl Viro 545bc40aee0SAl Viro if (nd->flags & LOOKUP_RCU) { 546bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 547bc40aee0SAl Viro GFP_ATOMIC); 548bc40aee0SAl Viro if (unlikely(!p)) 549bc40aee0SAl Viro return -ECHILD; 550bc40aee0SAl Viro } else { 551bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 552894bc8c4SAl Viro GFP_KERNEL); 553894bc8c4SAl Viro if (unlikely(!p)) 554894bc8c4SAl Viro return -ENOMEM; 555bc40aee0SAl Viro } 556894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 557894bc8c4SAl Viro nd->stack = p; 558894bc8c4SAl Viro return 0; 559894bc8c4SAl Viro } 560894bc8c4SAl Viro 561397d425dSEric W. Biederman /** 562397d425dSEric W. Biederman * path_connected - Verify that a path->dentry is below path->mnt.mnt_root 563397d425dSEric W. Biederman * @path: nameidate to verify 564397d425dSEric W. Biederman * 565397d425dSEric W. Biederman * Rename can sometimes move a file or directory outside of a bind 566397d425dSEric W. Biederman * mount, path_connected allows those cases to be detected. 567397d425dSEric W. Biederman */ 568397d425dSEric W. Biederman static bool path_connected(const struct path *path) 569397d425dSEric W. Biederman { 570397d425dSEric W. Biederman struct vfsmount *mnt = path->mnt; 571397d425dSEric W. Biederman 572397d425dSEric W. Biederman /* Only bind mounts can have disconnected paths */ 573397d425dSEric W. Biederman if (mnt->mnt_root == mnt->mnt_sb->s_root) 574397d425dSEric W. Biederman return true; 575397d425dSEric W. Biederman 576397d425dSEric W. Biederman return is_subdir(path->dentry, mnt->mnt_root); 577397d425dSEric W. Biederman } 578397d425dSEric W. Biederman 579894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 580894bc8c4SAl Viro { 581da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 582894bc8c4SAl Viro return 0; 583894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 584894bc8c4SAl Viro return 0; 585894bc8c4SAl Viro return __nd_alloc_stack(nd); 586894bc8c4SAl Viro } 587894bc8c4SAl Viro 5887973387aSAl Viro static void drop_links(struct nameidata *nd) 5897973387aSAl Viro { 5907973387aSAl Viro int i = nd->depth; 5917973387aSAl Viro while (i--) { 5927973387aSAl Viro struct saved *last = nd->stack + i; 5937973387aSAl Viro struct inode *inode = last->inode; 5947973387aSAl Viro if (last->cookie && inode->i_op->put_link) { 5957973387aSAl Viro inode->i_op->put_link(inode, last->cookie); 5967973387aSAl Viro last->cookie = NULL; 5977973387aSAl Viro } 5987973387aSAl Viro } 5997973387aSAl Viro } 6007973387aSAl Viro 6017973387aSAl Viro static void terminate_walk(struct nameidata *nd) 6027973387aSAl Viro { 6037973387aSAl Viro drop_links(nd); 6047973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 6057973387aSAl Viro int i; 6067973387aSAl Viro path_put(&nd->path); 6077973387aSAl Viro for (i = 0; i < nd->depth; i++) 6087973387aSAl Viro path_put(&nd->stack[i].link); 609102b8af2SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 610102b8af2SAl Viro path_put(&nd->root); 611102b8af2SAl Viro nd->root.mnt = NULL; 612102b8af2SAl Viro } 6137973387aSAl Viro } else { 6147973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 6157973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6167973387aSAl Viro nd->root.mnt = NULL; 6177973387aSAl Viro rcu_read_unlock(); 6187973387aSAl Viro } 6197973387aSAl Viro nd->depth = 0; 6207973387aSAl Viro } 6217973387aSAl Viro 6227973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 6237973387aSAl Viro static bool legitimize_path(struct nameidata *nd, 6247973387aSAl Viro struct path *path, unsigned seq) 6257973387aSAl Viro { 6267973387aSAl Viro int res = __legitimize_mnt(path->mnt, nd->m_seq); 6277973387aSAl Viro if (unlikely(res)) { 6287973387aSAl Viro if (res > 0) 6297973387aSAl Viro path->mnt = NULL; 6307973387aSAl Viro path->dentry = NULL; 6317973387aSAl Viro return false; 6327973387aSAl Viro } 6337973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 6347973387aSAl Viro path->dentry = NULL; 6357973387aSAl Viro return false; 6367973387aSAl Viro } 6377973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6387973387aSAl Viro } 6397973387aSAl Viro 6407973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6417973387aSAl Viro { 6427973387aSAl Viro int i; 6437973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6447973387aSAl Viro struct saved *last = nd->stack + i; 6457973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6467973387aSAl Viro drop_links(nd); 6477973387aSAl Viro nd->depth = i + 1; 6487973387aSAl Viro return false; 6497973387aSAl Viro } 6507973387aSAl Viro } 6517973387aSAl Viro return true; 6527973387aSAl Viro } 6537973387aSAl Viro 65419660af7SAl Viro /* 65531e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 65619660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 65719660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 65857e3715cSMike Marshall * normal reference counts on dentries and vfsmounts to transition to ref-walk 65919660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 66019660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 66119660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 66219660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 66331e6b01fSNick Piggin */ 66431e6b01fSNick Piggin 66531e6b01fSNick Piggin /** 66619660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 66719660af7SAl Viro * @nd: nameidata pathwalk data 66819660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 6696e9918b7SAl Viro * @seq: seq number to check dentry against 67039191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 67131e6b01fSNick Piggin * 67219660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 67319660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 67419660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 6757973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6767973387aSAl Viro * terminate_walk(). 67731e6b01fSNick Piggin */ 6786e9918b7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry, unsigned seq) 67931e6b01fSNick Piggin { 68031e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 68131e6b01fSNick Piggin 68231e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 683e5c832d5SLinus Torvalds 684e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6857973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6867973387aSAl Viro goto out2; 6877973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 6887973387aSAl Viro goto out2; 6897973387aSAl Viro if (unlikely(!lockref_get_not_dead(&parent->d_lockref))) 6907973387aSAl Viro goto out1; 69148a066e7SAl Viro 69215570086SLinus Torvalds /* 69315570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 69415570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 69515570086SLinus Torvalds * 69615570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 69715570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 69815570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 69915570086SLinus Torvalds * since we checked the sequence number of the parent after we got 70015570086SLinus Torvalds * the child sequence number. So we know the parent must still 70115570086SLinus Torvalds * be valid if the child sequence number is still valid. 70215570086SLinus Torvalds */ 70319660af7SAl Viro if (!dentry) { 704e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 705e5c832d5SLinus Torvalds goto out; 70619660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 70719660af7SAl Viro } else { 708e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 709e5c832d5SLinus Torvalds goto out; 7106e9918b7SAl Viro if (read_seqcount_retry(&dentry->d_seq, seq)) 711e5c832d5SLinus Torvalds goto drop_dentry; 71219660af7SAl Viro } 713e5c832d5SLinus Torvalds 714e5c832d5SLinus Torvalds /* 715e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 716e5c832d5SLinus Torvalds * still valid and get it if required. 717e5c832d5SLinus Torvalds */ 718e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 7195a8d87e8SAl Viro if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq))) { 7205a8d87e8SAl Viro rcu_read_unlock(); 7215a8d87e8SAl Viro dput(dentry); 7225a8d87e8SAl Viro return -ECHILD; 7237973387aSAl Viro } 72431e6b01fSNick Piggin } 72531e6b01fSNick Piggin 7268b61e74fSAl Viro rcu_read_unlock(); 72731e6b01fSNick Piggin return 0; 72819660af7SAl Viro 729e5c832d5SLinus Torvalds drop_dentry: 7308b61e74fSAl Viro rcu_read_unlock(); 731e5c832d5SLinus Torvalds dput(dentry); 732d0d27277SLinus Torvalds goto drop_root_mnt; 7337973387aSAl Viro out2: 7347973387aSAl Viro nd->path.mnt = NULL; 7357973387aSAl Viro out1: 7367973387aSAl Viro nd->path.dentry = NULL; 737e5c832d5SLinus Torvalds out: 7388b61e74fSAl Viro rcu_read_unlock(); 739d0d27277SLinus Torvalds drop_root_mnt: 740d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 741d0d27277SLinus Torvalds nd->root.mnt = NULL; 74231e6b01fSNick Piggin return -ECHILD; 74331e6b01fSNick Piggin } 74431e6b01fSNick Piggin 7457973387aSAl Viro static int unlazy_link(struct nameidata *nd, struct path *link, unsigned seq) 7467973387aSAl Viro { 7477973387aSAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 7487973387aSAl Viro drop_links(nd); 7497973387aSAl Viro nd->depth = 0; 7507973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 7517973387aSAl Viro nd->path.mnt = NULL; 7527973387aSAl Viro nd->path.dentry = NULL; 7537973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7547973387aSAl Viro nd->root.mnt = NULL; 7557973387aSAl Viro rcu_read_unlock(); 7567973387aSAl Viro } else if (likely(unlazy_walk(nd, NULL, 0)) == 0) { 7577973387aSAl Viro return 0; 7587973387aSAl Viro } 7597973387aSAl Viro path_put(link); 7607973387aSAl Viro return -ECHILD; 7617973387aSAl Viro } 7627973387aSAl Viro 7634ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 76434286d66SNick Piggin { 7654ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 76634286d66SNick Piggin } 76734286d66SNick Piggin 7689f1fafeeSAl Viro /** 7699f1fafeeSAl Viro * complete_walk - successful completion of path walk 7709f1fafeeSAl Viro * @nd: pointer nameidata 77139159de2SJeff Layton * 7729f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7739f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7749f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7759f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7769f1fafeeSAl Viro * need to drop nd->path. 77739159de2SJeff Layton */ 7789f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 77939159de2SJeff Layton { 78016c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 78139159de2SJeff Layton int status; 78239159de2SJeff Layton 7839f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 7849f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7859f1fafeeSAl Viro nd->root.mnt = NULL; 7866e9918b7SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 78748a066e7SAl Viro return -ECHILD; 78848a066e7SAl Viro } 7899f1fafeeSAl Viro 79016c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 79139159de2SJeff Layton return 0; 79239159de2SJeff Layton 793ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 79416c2cd71SAl Viro return 0; 79516c2cd71SAl Viro 796ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 79739159de2SJeff Layton if (status > 0) 79839159de2SJeff Layton return 0; 79939159de2SJeff Layton 80016c2cd71SAl Viro if (!status) 80139159de2SJeff Layton status = -ESTALE; 80216c2cd71SAl Viro 80339159de2SJeff Layton return status; 80439159de2SJeff Layton } 80539159de2SJeff Layton 80618d8c860SAl Viro static void set_root(struct nameidata *nd) 8072a737871SAl Viro { 80831e6b01fSNick Piggin struct fs_struct *fs = current->fs; 8099e6697e2SAl Viro 8109e6697e2SAl Viro if (nd->flags & LOOKUP_RCU) { 8118f47a016SAl Viro unsigned seq; 812c28cc364SNick Piggin 813c28cc364SNick Piggin do { 814c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 81531e6b01fSNick Piggin nd->root = fs->root; 8168f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 817c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 8189e6697e2SAl Viro } else { 8199e6697e2SAl Viro get_fs_root(fs, &nd->root); 8209e6697e2SAl Viro } 82131e6b01fSNick Piggin } 82231e6b01fSNick Piggin 8231d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 824051d3812SIan Kent { 825051d3812SIan Kent dput(path->dentry); 8264ac91378SJan Blunck if (path->mnt != nd->path.mnt) 827051d3812SIan Kent mntput(path->mnt); 828051d3812SIan Kent } 829051d3812SIan Kent 8307b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8317b9337aaSNick Piggin struct nameidata *nd) 832051d3812SIan Kent { 83331e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8344ac91378SJan Blunck dput(nd->path.dentry); 83531e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8364ac91378SJan Blunck mntput(nd->path.mnt); 8379a229683SHuang Shijie } 83831e6b01fSNick Piggin nd->path.mnt = path->mnt; 8394ac91378SJan Blunck nd->path.dentry = path->dentry; 840051d3812SIan Kent } 841051d3812SIan Kent 842248fb5b9SAl Viro static int nd_jump_root(struct nameidata *nd) 843248fb5b9SAl Viro { 844248fb5b9SAl Viro if (nd->flags & LOOKUP_RCU) { 845248fb5b9SAl Viro struct dentry *d; 846248fb5b9SAl Viro nd->path = nd->root; 847248fb5b9SAl Viro d = nd->path.dentry; 848248fb5b9SAl Viro nd->inode = d->d_inode; 849248fb5b9SAl Viro nd->seq = nd->root_seq; 850248fb5b9SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 851248fb5b9SAl Viro return -ECHILD; 852248fb5b9SAl Viro } else { 853248fb5b9SAl Viro path_put(&nd->path); 854248fb5b9SAl Viro nd->path = nd->root; 855248fb5b9SAl Viro path_get(&nd->path); 856248fb5b9SAl Viro nd->inode = nd->path.dentry->d_inode; 857248fb5b9SAl Viro } 858248fb5b9SAl Viro nd->flags |= LOOKUP_JUMPED; 859248fb5b9SAl Viro return 0; 860248fb5b9SAl Viro } 861248fb5b9SAl Viro 862b5fb63c1SChristoph Hellwig /* 863b5fb63c1SChristoph Hellwig * Helper to directly jump to a known parsed path from ->follow_link, 864b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 865b5fb63c1SChristoph Hellwig */ 8666e77137bSAl Viro void nd_jump_link(struct path *path) 867b5fb63c1SChristoph Hellwig { 8686e77137bSAl Viro struct nameidata *nd = current->nameidata; 869b5fb63c1SChristoph Hellwig path_put(&nd->path); 870b5fb63c1SChristoph Hellwig 871b5fb63c1SChristoph Hellwig nd->path = *path; 872b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 873b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 874b5fb63c1SChristoph Hellwig } 875b5fb63c1SChristoph Hellwig 876b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 877574197e0SAl Viro { 87821c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 879237d8b32SAl Viro struct inode *inode = last->inode; 880b9ff4429SAl Viro if (last->cookie && inode->i_op->put_link) 8815f2c4179SAl Viro inode->i_op->put_link(inode, last->cookie); 8826548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 883b9ff4429SAl Viro path_put(&last->link); 884574197e0SAl Viro } 885574197e0SAl Viro 886561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 887561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 888800179c9SKees Cook 889800179c9SKees Cook /** 890800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 89155852635SRandy Dunlap * @nd: nameidata pathwalk data 892800179c9SKees Cook * 893800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 894800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 895800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 896800179c9SKees Cook * processes from failing races against path names that may change out 897800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 898800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 899800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 900800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 901800179c9SKees Cook * 902800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 903800179c9SKees Cook */ 904fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 905800179c9SKees Cook { 906800179c9SKees Cook const struct inode *inode; 907800179c9SKees Cook const struct inode *parent; 908800179c9SKees Cook 909800179c9SKees Cook if (!sysctl_protected_symlinks) 910800179c9SKees Cook return 0; 911800179c9SKees Cook 912800179c9SKees Cook /* Allowed if owner and follower match. */ 913237d8b32SAl Viro inode = nd->stack[0].inode; 91481abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 915800179c9SKees Cook return 0; 916800179c9SKees Cook 917800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 918aa65fa35SAl Viro parent = nd->inode; 919800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 920800179c9SKees Cook return 0; 921800179c9SKees Cook 922800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 92381abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 924800179c9SKees Cook return 0; 925800179c9SKees Cook 92631956502SAl Viro if (nd->flags & LOOKUP_RCU) 92731956502SAl Viro return -ECHILD; 92831956502SAl Viro 9291cf2665bSAl Viro audit_log_link_denied("follow_link", &nd->stack[0].link); 930800179c9SKees Cook return -EACCES; 931800179c9SKees Cook } 932800179c9SKees Cook 933800179c9SKees Cook /** 934800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 935800179c9SKees Cook * @inode: the source inode to hardlink from 936800179c9SKees Cook * 937800179c9SKees Cook * Return false if at least one of the following conditions: 938800179c9SKees Cook * - inode is not a regular file 939800179c9SKees Cook * - inode is setuid 940800179c9SKees Cook * - inode is setgid and group-exec 941800179c9SKees Cook * - access failure for read and write 942800179c9SKees Cook * 943800179c9SKees Cook * Otherwise returns true. 944800179c9SKees Cook */ 945800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 946800179c9SKees Cook { 947800179c9SKees Cook umode_t mode = inode->i_mode; 948800179c9SKees Cook 949800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 950800179c9SKees Cook if (!S_ISREG(mode)) 951800179c9SKees Cook return false; 952800179c9SKees Cook 953800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 954800179c9SKees Cook if (mode & S_ISUID) 955800179c9SKees Cook return false; 956800179c9SKees Cook 957800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 958800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 959800179c9SKees Cook return false; 960800179c9SKees Cook 961800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 962800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 963800179c9SKees Cook return false; 964800179c9SKees Cook 965800179c9SKees Cook return true; 966800179c9SKees Cook } 967800179c9SKees Cook 968800179c9SKees Cook /** 969800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 970800179c9SKees Cook * @link: the source to hardlink from 971800179c9SKees Cook * 972800179c9SKees Cook * Block hardlink when all of: 973800179c9SKees Cook * - sysctl_protected_hardlinks enabled 974800179c9SKees Cook * - fsuid does not match inode 975800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 976f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 977800179c9SKees Cook * 978800179c9SKees Cook * Returns 0 if successful, -ve on error. 979800179c9SKees Cook */ 980800179c9SKees Cook static int may_linkat(struct path *link) 981800179c9SKees Cook { 982800179c9SKees Cook struct inode *inode; 983800179c9SKees Cook 984800179c9SKees Cook if (!sysctl_protected_hardlinks) 985800179c9SKees Cook return 0; 986800179c9SKees Cook 987800179c9SKees Cook inode = link->dentry->d_inode; 988800179c9SKees Cook 989800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 990800179c9SKees Cook * otherwise, it must be a safe source. 991800179c9SKees Cook */ 992f2ca3796SDirk Steinmetz if (inode_owner_or_capable(inode) || safe_hardlink_source(inode)) 993800179c9SKees Cook return 0; 994800179c9SKees Cook 995a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 996800179c9SKees Cook return -EPERM; 997800179c9SKees Cook } 998800179c9SKees Cook 9993b2e7f75SAl Viro static __always_inline 10003b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 10011da177e4SLinus Torvalds { 1002ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 10031cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 1004237d8b32SAl Viro struct inode *inode = last->inode; 10056d7b5aaeSAl Viro int error; 10060a959df5SAl Viro const char *res; 10071da177e4SLinus Torvalds 10088fa9dd24SNeilBrown if (!(nd->flags & LOOKUP_RCU)) { 10098fa9dd24SNeilBrown touch_atime(&last->link); 10108fa9dd24SNeilBrown cond_resched(); 10118fa9dd24SNeilBrown } else if (atime_needs_update(&last->link, inode)) { 10128fa9dd24SNeilBrown if (unlikely(unlazy_walk(nd, NULL, 0))) 10138fa9dd24SNeilBrown return ERR_PTR(-ECHILD); 10148fa9dd24SNeilBrown touch_atime(&last->link); 10158fa9dd24SNeilBrown } 10168fa9dd24SNeilBrown 1017bda0be7aSNeilBrown error = security_inode_follow_link(dentry, inode, 1018bda0be7aSNeilBrown nd->flags & LOOKUP_RCU); 1019bda0be7aSNeilBrown if (unlikely(error)) 10206920a440SAl Viro return ERR_PTR(error); 102136f3b4f6SAl Viro 102286acdca1SAl Viro nd->last_type = LAST_BIND; 1023d4dee48bSAl Viro res = inode->i_link; 1024d4dee48bSAl Viro if (!res) { 10258c1b4566SAl Viro if (nd->flags & LOOKUP_RCU) { 10268c1b4566SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 10278c1b4566SAl Viro return ERR_PTR(-ECHILD); 10288c1b4566SAl Viro } 10296e77137bSAl Viro res = inode->i_op->follow_link(dentry, &last->cookie); 1030fab51e8aSAl Viro if (IS_ERR_OR_NULL(res)) { 10316920a440SAl Viro last->cookie = NULL; 1032fab51e8aSAl Viro return res; 10330a959df5SAl Viro } 1034fab51e8aSAl Viro } 1035fab51e8aSAl Viro if (*res == '/') { 10369e6697e2SAl Viro if (!nd->root.mnt) 10379e6697e2SAl Viro set_root(nd); 1038248fb5b9SAl Viro if (unlikely(nd_jump_root(nd))) 10398c1b4566SAl Viro return ERR_PTR(-ECHILD); 1040fab51e8aSAl Viro while (unlikely(*++res == '/')) 1041fab51e8aSAl Viro ; 1042fab51e8aSAl Viro } 1043fab51e8aSAl Viro if (!*res) 1044fab51e8aSAl Viro res = NULL; 10450a959df5SAl Viro return res; 10460a959df5SAl Viro } 10476d7b5aaeSAl Viro 1048f015f126SDavid Howells /* 1049f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1050f015f126SDavid Howells * 1051f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1052f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1053f015f126SDavid Howells * Up is towards /. 1054f015f126SDavid Howells * 1055f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1056f015f126SDavid Howells * root. 1057f015f126SDavid Howells */ 1058bab77ebfSAl Viro int follow_up(struct path *path) 10591da177e4SLinus Torvalds { 10600714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 10610714a533SAl Viro struct mount *parent; 10621da177e4SLinus Torvalds struct dentry *mountpoint; 106399b7db7bSNick Piggin 106448a066e7SAl Viro read_seqlock_excl(&mount_lock); 10650714a533SAl Viro parent = mnt->mnt_parent; 10663c0a6163SAl Viro if (parent == mnt) { 106748a066e7SAl Viro read_sequnlock_excl(&mount_lock); 10681da177e4SLinus Torvalds return 0; 10691da177e4SLinus Torvalds } 10700714a533SAl Viro mntget(&parent->mnt); 1071a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 107248a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1073bab77ebfSAl Viro dput(path->dentry); 1074bab77ebfSAl Viro path->dentry = mountpoint; 1075bab77ebfSAl Viro mntput(path->mnt); 10760714a533SAl Viro path->mnt = &parent->mnt; 10771da177e4SLinus Torvalds return 1; 10781da177e4SLinus Torvalds } 10794d359507SAl Viro EXPORT_SYMBOL(follow_up); 10801da177e4SLinus Torvalds 1081b5c84bf6SNick Piggin /* 10829875cf80SDavid Howells * Perform an automount 10839875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 10849875cf80SDavid Howells * were called with. 10851da177e4SLinus Torvalds */ 1086756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 10879875cf80SDavid Howells bool *need_mntput) 108831e6b01fSNick Piggin { 10899875cf80SDavid Howells struct vfsmount *mnt; 1090ea5b778aSDavid Howells int err; 10919875cf80SDavid Howells 10929875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 10939875cf80SDavid Howells return -EREMOTE; 10949875cf80SDavid Howells 10950ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 10960ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 10970ec26fd0SMiklos Szeredi * the name. 10980ec26fd0SMiklos Szeredi * 10990ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 11005a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 11010ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 11020ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 11030ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 11040ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 11055a30d8a2SDavid Howells */ 1106756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 1107d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 11085a30d8a2SDavid Howells path->dentry->d_inode) 11099875cf80SDavid Howells return -EISDIR; 11100ec26fd0SMiklos Szeredi 1111756daf26SNeilBrown nd->total_link_count++; 1112756daf26SNeilBrown if (nd->total_link_count >= 40) 11139875cf80SDavid Howells return -ELOOP; 11149875cf80SDavid Howells 11159875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 11169875cf80SDavid Howells if (IS_ERR(mnt)) { 11179875cf80SDavid Howells /* 11189875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 11199875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 11209875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 11219875cf80SDavid Howells * 11229875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 11239875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 11249875cf80SDavid Howells * the path is inaccessible and we should say so. 11259875cf80SDavid Howells */ 1126756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 11279875cf80SDavid Howells return -EREMOTE; 11289875cf80SDavid Howells return PTR_ERR(mnt); 112931e6b01fSNick Piggin } 1130ea5b778aSDavid Howells 11319875cf80SDavid Howells if (!mnt) /* mount collision */ 11329875cf80SDavid Howells return 0; 11339875cf80SDavid Howells 11348aef1884SAl Viro if (!*need_mntput) { 11358aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 11368aef1884SAl Viro mntget(path->mnt); 11378aef1884SAl Viro *need_mntput = true; 11388aef1884SAl Viro } 113919a167afSAl Viro err = finish_automount(mnt, path); 1140ea5b778aSDavid Howells 1141ea5b778aSDavid Howells switch (err) { 1142ea5b778aSDavid Howells case -EBUSY: 1143ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 114419a167afSAl Viro return 0; 1145ea5b778aSDavid Howells case 0: 11468aef1884SAl Viro path_put(path); 11479875cf80SDavid Howells path->mnt = mnt; 11489875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 11499875cf80SDavid Howells return 0; 115019a167afSAl Viro default: 115119a167afSAl Viro return err; 11529875cf80SDavid Howells } 115319a167afSAl Viro 1154ea5b778aSDavid Howells } 11559875cf80SDavid Howells 11569875cf80SDavid Howells /* 11579875cf80SDavid Howells * Handle a dentry that is managed in some way. 1158cc53ce53SDavid Howells * - Flagged for transit management (autofs) 11599875cf80SDavid Howells * - Flagged as mountpoint 11609875cf80SDavid Howells * - Flagged as automount point 11619875cf80SDavid Howells * 11629875cf80SDavid Howells * This may only be called in refwalk mode. 11639875cf80SDavid Howells * 11649875cf80SDavid Howells * Serialization is taken care of in namespace.c 11659875cf80SDavid Howells */ 1166756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 11679875cf80SDavid Howells { 11688aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 11699875cf80SDavid Howells unsigned managed; 11709875cf80SDavid Howells bool need_mntput = false; 11718aef1884SAl Viro int ret = 0; 11729875cf80SDavid Howells 11739875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 11749875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 11759875cf80SDavid Howells * the components of that value change under us */ 11769875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 11779875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 11789875cf80SDavid Howells unlikely(managed != 0)) { 1179cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1180cc53ce53SDavid Howells * being held. */ 1181cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1182cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1183cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 11841aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1185cc53ce53SDavid Howells if (ret < 0) 11868aef1884SAl Viro break; 1187cc53ce53SDavid Howells } 1188cc53ce53SDavid Howells 11899875cf80SDavid Howells /* Transit to a mounted filesystem. */ 11909875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 11919875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 11929875cf80SDavid Howells if (mounted) { 11939875cf80SDavid Howells dput(path->dentry); 11949875cf80SDavid Howells if (need_mntput) 1195463ffb2eSAl Viro mntput(path->mnt); 1196463ffb2eSAl Viro path->mnt = mounted; 1197463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 11989875cf80SDavid Howells need_mntput = true; 11999875cf80SDavid Howells continue; 1200463ffb2eSAl Viro } 1201463ffb2eSAl Viro 12029875cf80SDavid Howells /* Something is mounted on this dentry in another 12039875cf80SDavid Howells * namespace and/or whatever was mounted there in this 120448a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 120548a066e7SAl Viro * get it */ 12061da177e4SLinus Torvalds } 12079875cf80SDavid Howells 12089875cf80SDavid Howells /* Handle an automount point */ 12099875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1210756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 12119875cf80SDavid Howells if (ret < 0) 12128aef1884SAl Viro break; 12139875cf80SDavid Howells continue; 12149875cf80SDavid Howells } 12159875cf80SDavid Howells 12169875cf80SDavid Howells /* We didn't change the current path point */ 12179875cf80SDavid Howells break; 12189875cf80SDavid Howells } 12198aef1884SAl Viro 12208aef1884SAl Viro if (need_mntput && path->mnt == mnt) 12218aef1884SAl Viro mntput(path->mnt); 12228aef1884SAl Viro if (ret == -EISDIR) 12238aef1884SAl Viro ret = 0; 12248402752eSAl Viro if (need_mntput) 12258402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 12268402752eSAl Viro if (unlikely(ret < 0)) 12278402752eSAl Viro path_put_conditional(path, nd); 12288402752eSAl Viro return ret; 12291da177e4SLinus Torvalds } 12301da177e4SLinus Torvalds 1231cc53ce53SDavid Howells int follow_down_one(struct path *path) 12321da177e4SLinus Torvalds { 12331da177e4SLinus Torvalds struct vfsmount *mounted; 12341da177e4SLinus Torvalds 12351c755af4SAl Viro mounted = lookup_mnt(path); 12361da177e4SLinus Torvalds if (mounted) { 12379393bd07SAl Viro dput(path->dentry); 12389393bd07SAl Viro mntput(path->mnt); 12399393bd07SAl Viro path->mnt = mounted; 12409393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12411da177e4SLinus Torvalds return 1; 12421da177e4SLinus Torvalds } 12431da177e4SLinus Torvalds return 0; 12441da177e4SLinus Torvalds } 12454d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12461da177e4SLinus Torvalds 1247b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 124862a7375eSIan Kent { 1249b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1250b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 125162a7375eSIan Kent } 125262a7375eSIan Kent 12539875cf80SDavid Howells /* 1254287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1255287548e4SAl Viro * we meet a managed dentry that would need blocking. 12569875cf80SDavid Howells */ 12579875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1258254cf582SAl Viro struct inode **inode, unsigned *seqp) 12599875cf80SDavid Howells { 126062a7375eSIan Kent for (;;) { 1261c7105365SAl Viro struct mount *mounted; 126262a7375eSIan Kent /* 126362a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 126462a7375eSIan Kent * that wants to block transit. 126562a7375eSIan Kent */ 1266b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1267b8faf035SNeilBrown case -ECHILD: 1268b8faf035SNeilBrown default: 1269ab90911fSDavid Howells return false; 1270b8faf035SNeilBrown case -EISDIR: 1271b8faf035SNeilBrown return true; 1272b8faf035SNeilBrown case 0: 1273b8faf035SNeilBrown break; 1274b8faf035SNeilBrown } 127562a7375eSIan Kent 127662a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1277b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 127862a7375eSIan Kent 1279474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 12809875cf80SDavid Howells if (!mounted) 12819875cf80SDavid Howells break; 1282c7105365SAl Viro path->mnt = &mounted->mnt; 1283c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1284a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1285254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 128659430262SLinus Torvalds /* 128759430262SLinus Torvalds * Update the inode too. We don't need to re-check the 128859430262SLinus Torvalds * dentry sequence number here after this d_inode read, 128959430262SLinus Torvalds * because a mount-point is always pinned. 129059430262SLinus Torvalds */ 129159430262SLinus Torvalds *inode = path->dentry->d_inode; 12929875cf80SDavid Howells } 1293f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1294b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1295287548e4SAl Viro } 1296287548e4SAl Viro 129731e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 129831e6b01fSNick Piggin { 12994023bfc9SAl Viro struct inode *inode = nd->inode; 130031e6b01fSNick Piggin 130131e6b01fSNick Piggin while (1) { 1302aed434adSAl Viro if (path_equal(&nd->path, &nd->root)) 130331e6b01fSNick Piggin break; 130431e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 130531e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 130631e6b01fSNick Piggin struct dentry *parent = old->d_parent; 130731e6b01fSNick Piggin unsigned seq; 130831e6b01fSNick Piggin 13094023bfc9SAl Viro inode = parent->d_inode; 131031e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 1311aed434adSAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 1312aed434adSAl Viro return -ECHILD; 131331e6b01fSNick Piggin nd->path.dentry = parent; 131431e6b01fSNick Piggin nd->seq = seq; 1315397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 1316397d425dSEric W. Biederman return -ENOENT; 131731e6b01fSNick Piggin break; 1318aed434adSAl Viro } else { 1319aed434adSAl Viro struct mount *mnt = real_mount(nd->path.mnt); 1320aed434adSAl Viro struct mount *mparent = mnt->mnt_parent; 1321aed434adSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1322aed434adSAl Viro struct inode *inode2 = mountpoint->d_inode; 1323aed434adSAl Viro unsigned seq = read_seqcount_begin(&mountpoint->d_seq); 1324aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1325aed434adSAl Viro return -ECHILD; 1326aed434adSAl Viro if (&mparent->mnt == nd->path.mnt) 132731e6b01fSNick Piggin break; 1328aed434adSAl Viro /* we know that mountpoint was pinned */ 1329aed434adSAl Viro nd->path.dentry = mountpoint; 1330aed434adSAl Viro nd->path.mnt = &mparent->mnt; 1331aed434adSAl Viro inode = inode2; 1332aed434adSAl Viro nd->seq = seq; 133331e6b01fSNick Piggin } 1334aed434adSAl Viro } 1335aed434adSAl Viro while (unlikely(d_mountpoint(nd->path.dentry))) { 1336b37199e6SAl Viro struct mount *mounted; 1337b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1338aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1339aed434adSAl Viro return -ECHILD; 1340b37199e6SAl Viro if (!mounted) 1341b37199e6SAl Viro break; 1342b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1343b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 13444023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1345b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1346b37199e6SAl Viro } 13474023bfc9SAl Viro nd->inode = inode; 134831e6b01fSNick Piggin return 0; 134931e6b01fSNick Piggin } 135031e6b01fSNick Piggin 13519875cf80SDavid Howells /* 1352cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1353cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1354cc53ce53SDavid Howells * caller is permitted to proceed or not. 1355cc53ce53SDavid Howells */ 13567cc90cc3SAl Viro int follow_down(struct path *path) 1357cc53ce53SDavid Howells { 1358cc53ce53SDavid Howells unsigned managed; 1359cc53ce53SDavid Howells int ret; 1360cc53ce53SDavid Howells 1361cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1362cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1363cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1364cc53ce53SDavid Howells * being held. 1365cc53ce53SDavid Howells * 1366cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1367cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1368cc53ce53SDavid Howells * other than its daemon the right to mount on its 1369cc53ce53SDavid Howells * superstructure. 1370cc53ce53SDavid Howells * 1371cc53ce53SDavid Howells * The filesystem may sleep at this point. 1372cc53ce53SDavid Howells */ 1373cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1374cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1375cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1376ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 13771aed3e42SAl Viro path->dentry, false); 1378cc53ce53SDavid Howells if (ret < 0) 1379cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1380cc53ce53SDavid Howells } 1381cc53ce53SDavid Howells 1382cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1383cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1384cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1385cc53ce53SDavid Howells if (!mounted) 1386cc53ce53SDavid Howells break; 1387cc53ce53SDavid Howells dput(path->dentry); 1388cc53ce53SDavid Howells mntput(path->mnt); 1389cc53ce53SDavid Howells path->mnt = mounted; 1390cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1391cc53ce53SDavid Howells continue; 1392cc53ce53SDavid Howells } 1393cc53ce53SDavid Howells 1394cc53ce53SDavid Howells /* Don't handle automount points here */ 1395cc53ce53SDavid Howells break; 1396cc53ce53SDavid Howells } 1397cc53ce53SDavid Howells return 0; 1398cc53ce53SDavid Howells } 13994d359507SAl Viro EXPORT_SYMBOL(follow_down); 1400cc53ce53SDavid Howells 1401cc53ce53SDavid Howells /* 14029875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 14039875cf80SDavid Howells */ 14049875cf80SDavid Howells static void follow_mount(struct path *path) 14059875cf80SDavid Howells { 14069875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 14079875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 14089875cf80SDavid Howells if (!mounted) 14099875cf80SDavid Howells break; 14109875cf80SDavid Howells dput(path->dentry); 14119875cf80SDavid Howells mntput(path->mnt); 14129875cf80SDavid Howells path->mnt = mounted; 14139875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 14149875cf80SDavid Howells } 14159875cf80SDavid Howells } 14169875cf80SDavid Howells 1417397d425dSEric W. Biederman static int follow_dotdot(struct nameidata *nd) 14181da177e4SLinus Torvalds { 14191da177e4SLinus Torvalds while(1) { 14204ac91378SJan Blunck struct dentry *old = nd->path.dentry; 14211da177e4SLinus Torvalds 14222a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 14232a737871SAl Viro nd->path.mnt == nd->root.mnt) { 14241da177e4SLinus Torvalds break; 14251da177e4SLinus Torvalds } 14264ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 14273088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 14283088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 14291da177e4SLinus Torvalds dput(old); 1430397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 1431397d425dSEric W. Biederman return -ENOENT; 14321da177e4SLinus Torvalds break; 14331da177e4SLinus Torvalds } 14343088dd70SAl Viro if (!follow_up(&nd->path)) 14351da177e4SLinus Torvalds break; 14361da177e4SLinus Torvalds } 143779ed0226SAl Viro follow_mount(&nd->path); 143831e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 1439397d425dSEric W. Biederman return 0; 14401da177e4SLinus Torvalds } 14411da177e4SLinus Torvalds 14421da177e4SLinus Torvalds /* 1443bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1444bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1445bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1446bad61189SMiklos Szeredi * 1447bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1448baa03890SNick Piggin */ 1449bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1450201f956eSAl Viro unsigned int flags, bool *need_lookup) 1451baa03890SNick Piggin { 1452baa03890SNick Piggin struct dentry *dentry; 1453bad61189SMiklos Szeredi int error; 1454baa03890SNick Piggin 1455bad61189SMiklos Szeredi *need_lookup = false; 1456bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1457bad61189SMiklos Szeredi if (dentry) { 145839e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1459201f956eSAl Viro error = d_revalidate(dentry, flags); 1460bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1461bad61189SMiklos Szeredi if (error < 0) { 1462bad61189SMiklos Szeredi dput(dentry); 1463bad61189SMiklos Szeredi return ERR_PTR(error); 14645542aa2fSEric W. Biederman } else { 14655542aa2fSEric W. Biederman d_invalidate(dentry); 1466bad61189SMiklos Szeredi dput(dentry); 1467bad61189SMiklos Szeredi dentry = NULL; 1468bad61189SMiklos Szeredi } 1469bad61189SMiklos Szeredi } 1470bad61189SMiklos Szeredi } 1471bad61189SMiklos Szeredi } 1472baa03890SNick Piggin 1473bad61189SMiklos Szeredi if (!dentry) { 1474bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1475baa03890SNick Piggin if (unlikely(!dentry)) 1476baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1477baa03890SNick Piggin 1478bad61189SMiklos Szeredi *need_lookup = true; 1479baa03890SNick Piggin } 1480baa03890SNick Piggin return dentry; 1481baa03890SNick Piggin } 1482baa03890SNick Piggin 1483baa03890SNick Piggin /* 148413a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 148513a2c3beSJ. Bruce Fields * unhashed. 1486bad61189SMiklos Szeredi * 1487bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 148844396f4bSJosef Bacik */ 1489bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 149072bd866aSAl Viro unsigned int flags) 149144396f4bSJosef Bacik { 149244396f4bSJosef Bacik struct dentry *old; 149344396f4bSJosef Bacik 149444396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1495bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1496e188dc02SMiklos Szeredi dput(dentry); 149744396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1498e188dc02SMiklos Szeredi } 149944396f4bSJosef Bacik 150072bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 150144396f4bSJosef Bacik if (unlikely(old)) { 150244396f4bSJosef Bacik dput(dentry); 150344396f4bSJosef Bacik dentry = old; 150444396f4bSJosef Bacik } 150544396f4bSJosef Bacik return dentry; 150644396f4bSJosef Bacik } 150744396f4bSJosef Bacik 1508a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 150972bd866aSAl Viro struct dentry *base, unsigned int flags) 1510a3255546SAl Viro { 1511bad61189SMiklos Szeredi bool need_lookup; 1512a3255546SAl Viro struct dentry *dentry; 1513a3255546SAl Viro 151472bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1515bad61189SMiklos Szeredi if (!need_lookup) 1516a3255546SAl Viro return dentry; 1517bad61189SMiklos Szeredi 151872bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1519a3255546SAl Viro } 1520a3255546SAl Viro 152144396f4bSJosef Bacik /* 15221da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 15231da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 15241da177e4SLinus Torvalds * It _is_ time-critical. 15251da177e4SLinus Torvalds */ 1526e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 1527254cf582SAl Viro struct path *path, struct inode **inode, 1528254cf582SAl Viro unsigned *seqp) 15291da177e4SLinus Torvalds { 15304ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 153131e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 15325a18fff2SAl Viro int need_reval = 1; 15335a18fff2SAl Viro int status = 1; 15349875cf80SDavid Howells int err; 15359875cf80SDavid Howells 15363cac260aSAl Viro /* 1537b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1538b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1539b04f784eSNick Piggin * do the non-racy lookup, below. 1540b04f784eSNick Piggin */ 154131e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 154231e6b01fSNick Piggin unsigned seq; 1543766c4cbfSAl Viro bool negative; 1544da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15455a18fff2SAl Viro if (!dentry) 15465a18fff2SAl Viro goto unlazy; 15475a18fff2SAl Viro 154812f8ad4bSLinus Torvalds /* 154912f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 155012f8ad4bSLinus Torvalds * the dentry name information from lookup. 155112f8ad4bSLinus Torvalds */ 155263afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1553766c4cbfSAl Viro negative = d_is_negative(dentry); 155412f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 155512f8ad4bSLinus Torvalds return -ECHILD; 155612f8ad4bSLinus Torvalds 155712f8ad4bSLinus Torvalds /* 155812f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 155912f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 156012f8ad4bSLinus Torvalds * 156112f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 156212f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 156312f8ad4bSLinus Torvalds */ 156431e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 156531e6b01fSNick Piggin return -ECHILD; 15665a18fff2SAl Viro 1567254cf582SAl Viro *seqp = seq; 156824643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 15694ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15705a18fff2SAl Viro if (unlikely(status <= 0)) { 15715a18fff2SAl Viro if (status != -ECHILD) 15725a18fff2SAl Viro need_reval = 0; 15735a18fff2SAl Viro goto unlazy; 15745a18fff2SAl Viro } 157524643087SAl Viro } 1576daf3761cSTrond Myklebust /* 1577daf3761cSTrond Myklebust * Note: do negative dentry check after revalidation in 1578daf3761cSTrond Myklebust * case that drops it. 1579daf3761cSTrond Myklebust */ 1580daf3761cSTrond Myklebust if (negative) 1581daf3761cSTrond Myklebust return -ENOENT; 158231e6b01fSNick Piggin path->mnt = mnt; 158331e6b01fSNick Piggin path->dentry = dentry; 1584254cf582SAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 15859875cf80SDavid Howells return 0; 15865a18fff2SAl Viro unlazy: 1587254cf582SAl Viro if (unlazy_walk(nd, dentry, seq)) 15885a18fff2SAl Viro return -ECHILD; 15895a18fff2SAl Viro } else { 1590e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 159124643087SAl Viro } 15925a18fff2SAl Viro 159381e6f520SAl Viro if (unlikely(!dentry)) 159481e6f520SAl Viro goto need_lookup; 15955a18fff2SAl Viro 15965a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 15974ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15985a18fff2SAl Viro if (unlikely(status <= 0)) { 15995a18fff2SAl Viro if (status < 0) { 16005a18fff2SAl Viro dput(dentry); 16015a18fff2SAl Viro return status; 16025a18fff2SAl Viro } 16035542aa2fSEric W. Biederman d_invalidate(dentry); 16045a18fff2SAl Viro dput(dentry); 160581e6f520SAl Viro goto need_lookup; 16065a18fff2SAl Viro } 1607697f514dSMiklos Szeredi 1608766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1609766c4cbfSAl Viro dput(dentry); 1610766c4cbfSAl Viro return -ENOENT; 1611766c4cbfSAl Viro } 16121da177e4SLinus Torvalds path->mnt = mnt; 16131da177e4SLinus Torvalds path->dentry = dentry; 1614756daf26SNeilBrown err = follow_managed(path, nd); 16158402752eSAl Viro if (likely(!err)) 161663afdfc7SDavid Howells *inode = d_backing_inode(path->dentry); 16178402752eSAl Viro return err; 161881e6f520SAl Viro 161981e6f520SAl Viro need_lookup: 1620697f514dSMiklos Szeredi return 1; 1621697f514dSMiklos Szeredi } 1622697f514dSMiklos Szeredi 1623697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1624cc2a5271SAl Viro static int lookup_slow(struct nameidata *nd, struct path *path) 1625697f514dSMiklos Szeredi { 1626697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1627697f514dSMiklos Szeredi 1628697f514dSMiklos Szeredi parent = nd->path.dentry; 162981e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 163081e6f520SAl Viro 163181e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 1632cc2a5271SAl Viro dentry = __lookup_hash(&nd->last, parent, nd->flags); 163381e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 163481e6f520SAl Viro if (IS_ERR(dentry)) 163581e6f520SAl Viro return PTR_ERR(dentry); 1636697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1637697f514dSMiklos Szeredi path->dentry = dentry; 16388402752eSAl Viro return follow_managed(path, nd); 16391da177e4SLinus Torvalds } 16401da177e4SLinus Torvalds 164152094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 164252094c8aSAl Viro { 164352094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16444ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 164552094c8aSAl Viro if (err != -ECHILD) 164652094c8aSAl Viro return err; 16476e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 164852094c8aSAl Viro return -ECHILD; 164952094c8aSAl Viro } 16504ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 165152094c8aSAl Viro } 165252094c8aSAl Viro 16539856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 16549856fa1bSAl Viro { 16559856fa1bSAl Viro if (type == LAST_DOTDOT) { 16569e6697e2SAl Viro if (!nd->root.mnt) 16579e6697e2SAl Viro set_root(nd); 16589856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 165970291aecSAl Viro return follow_dotdot_rcu(nd); 16609856fa1bSAl Viro } else 1661397d425dSEric W. Biederman return follow_dotdot(nd); 16629856fa1bSAl Viro } 16639856fa1bSAl Viro return 0; 16649856fa1bSAl Viro } 16659856fa1bSAl Viro 1666181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1667181548c0SAl Viro struct inode *inode, unsigned seq) 1668d63ff28fSAl Viro { 1669626de996SAl Viro int error; 16701cf2665bSAl Viro struct saved *last; 1671756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1672626de996SAl Viro path_to_nameidata(link, nd); 1673626de996SAl Viro return -ELOOP; 1674626de996SAl Viro } 1675bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1676cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1677cd179f44SAl Viro mntget(link->mnt); 16787973387aSAl Viro } 1679626de996SAl Viro error = nd_alloc_stack(nd); 1680626de996SAl Viro if (unlikely(error)) { 1681bc40aee0SAl Viro if (error == -ECHILD) { 1682bc40aee0SAl Viro if (unlikely(unlazy_link(nd, link, seq))) 1683bc40aee0SAl Viro return -ECHILD; 1684bc40aee0SAl Viro error = nd_alloc_stack(nd); 1685bc40aee0SAl Viro } 1686bc40aee0SAl Viro if (error) { 1687cd179f44SAl Viro path_put(link); 1688626de996SAl Viro return error; 1689626de996SAl Viro } 1690bc40aee0SAl Viro } 1691626de996SAl Viro 1692ab104923SAl Viro last = nd->stack + nd->depth++; 16931cf2665bSAl Viro last->link = *link; 1694ab104923SAl Viro last->cookie = NULL; 1695181548c0SAl Viro last->inode = inode; 16960450b2d1SAl Viro last->seq = seq; 1697d63ff28fSAl Viro return 1; 1698d63ff28fSAl Viro } 1699d63ff28fSAl Viro 17003ddcd056SLinus Torvalds /* 17013ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 17023ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 17033ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 17043ddcd056SLinus Torvalds * for the common case. 17053ddcd056SLinus Torvalds */ 1706254cf582SAl Viro static inline int should_follow_link(struct nameidata *nd, struct path *link, 1707181548c0SAl Viro int follow, 1708181548c0SAl Viro struct inode *inode, unsigned seq) 17093ddcd056SLinus Torvalds { 1710d63ff28fSAl Viro if (likely(!d_is_symlink(link->dentry))) 1711d63ff28fSAl Viro return 0; 1712d63ff28fSAl Viro if (!follow) 1713d63ff28fSAl Viro return 0; 1714181548c0SAl Viro return pick_link(nd, link, inode, seq); 17153ddcd056SLinus Torvalds } 17163ddcd056SLinus Torvalds 17174693a547SAl Viro enum {WALK_GET = 1, WALK_PUT = 2}; 17184693a547SAl Viro 17194693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1720ce57dfc1SAl Viro { 1721caa85634SAl Viro struct path path; 1722ce57dfc1SAl Viro struct inode *inode; 1723254cf582SAl Viro unsigned seq; 1724ce57dfc1SAl Viro int err; 1725ce57dfc1SAl Viro /* 1726ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1727ce57dfc1SAl Viro * to be able to know about the current root directory and 1728ce57dfc1SAl Viro * parent relationships. 1729ce57dfc1SAl Viro */ 17304693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 17314693a547SAl Viro err = handle_dots(nd, nd->last_type); 17324693a547SAl Viro if (flags & WALK_PUT) 17334693a547SAl Viro put_link(nd); 17344693a547SAl Viro return err; 17354693a547SAl Viro } 1736254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1737ce57dfc1SAl Viro if (unlikely(err)) { 1738697f514dSMiklos Szeredi if (err < 0) 1739f0a9ba70SAl Viro return err; 1740697f514dSMiklos Szeredi 1741caa85634SAl Viro err = lookup_slow(nd, &path); 1742697f514dSMiklos Szeredi if (err < 0) 1743f0a9ba70SAl Viro return err; 1744697f514dSMiklos Szeredi 174563afdfc7SDavid Howells inode = d_backing_inode(path.dentry); 1746254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1747697f514dSMiklos Szeredi err = -ENOENT; 1748caa85634SAl Viro if (d_is_negative(path.dentry)) 1749697f514dSMiklos Szeredi goto out_path_put; 1750766c4cbfSAl Viro } 1751697f514dSMiklos Szeredi 17524693a547SAl Viro if (flags & WALK_PUT) 17534693a547SAl Viro put_link(nd); 1754181548c0SAl Viro err = should_follow_link(nd, &path, flags & WALK_GET, inode, seq); 1755d63ff28fSAl Viro if (unlikely(err)) 1756d63ff28fSAl Viro return err; 1757caa85634SAl Viro path_to_nameidata(&path, nd); 1758ce57dfc1SAl Viro nd->inode = inode; 1759254cf582SAl Viro nd->seq = seq; 1760ce57dfc1SAl Viro return 0; 1761697f514dSMiklos Szeredi 1762697f514dSMiklos Szeredi out_path_put: 1763caa85634SAl Viro path_to_nameidata(&path, nd); 1764697f514dSMiklos Szeredi return err; 1765ce57dfc1SAl Viro } 1766ce57dfc1SAl Viro 17671da177e4SLinus Torvalds /* 1768bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1769bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1770bfcfaa77SLinus Torvalds * 1771bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1772bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1773bfcfaa77SLinus Torvalds * fast. 1774bfcfaa77SLinus Torvalds * 1775bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1776bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1777bfcfaa77SLinus Torvalds * crossing operation. 1778bfcfaa77SLinus Torvalds * 1779bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1780bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1781bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1782bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1783bfcfaa77SLinus Torvalds */ 1784bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1785bfcfaa77SLinus Torvalds 1786f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1787bfcfaa77SLinus Torvalds 1788f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1789bfcfaa77SLinus Torvalds 1790bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1791bfcfaa77SLinus Torvalds { 179299d263d4SLinus Torvalds return hash_64(hash, 32); 1793bfcfaa77SLinus Torvalds } 1794bfcfaa77SLinus Torvalds 1795bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1796bfcfaa77SLinus Torvalds 1797bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1798bfcfaa77SLinus Torvalds 1799bfcfaa77SLinus Torvalds #endif 1800bfcfaa77SLinus Torvalds 1801bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1802bfcfaa77SLinus Torvalds { 1803bfcfaa77SLinus Torvalds unsigned long a, mask; 1804bfcfaa77SLinus Torvalds unsigned long hash = 0; 1805bfcfaa77SLinus Torvalds 1806bfcfaa77SLinus Torvalds for (;;) { 1807e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1808bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1809bfcfaa77SLinus Torvalds break; 1810bfcfaa77SLinus Torvalds hash += a; 1811f132c5beSAl Viro hash *= 9; 1812bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1813bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1814bfcfaa77SLinus Torvalds if (!len) 1815bfcfaa77SLinus Torvalds goto done; 1816bfcfaa77SLinus Torvalds } 1817a5c21dceSWill Deacon mask = bytemask_from_count(len); 1818bfcfaa77SLinus Torvalds hash += mask & a; 1819bfcfaa77SLinus Torvalds done: 1820bfcfaa77SLinus Torvalds return fold_hash(hash); 1821bfcfaa77SLinus Torvalds } 1822bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1823bfcfaa77SLinus Torvalds 1824bfcfaa77SLinus Torvalds /* 1825bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1826d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1827bfcfaa77SLinus Torvalds */ 1828d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1829bfcfaa77SLinus Torvalds { 183036126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 183136126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1832bfcfaa77SLinus Torvalds 1833bfcfaa77SLinus Torvalds hash = a = 0; 1834bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1835bfcfaa77SLinus Torvalds do { 1836bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1837bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1838e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 183936126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 184036126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1841bfcfaa77SLinus Torvalds 184236126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 184336126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 184436126f8fSLinus Torvalds 184536126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 184636126f8fSLinus Torvalds 184736126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 18489226b5b4SLinus Torvalds len += find_zero(mask); 1849d6bb3e90SLinus Torvalds return hashlen_create(fold_hash(hash), len); 1850bfcfaa77SLinus Torvalds } 1851bfcfaa77SLinus Torvalds 1852bfcfaa77SLinus Torvalds #else 1853bfcfaa77SLinus Torvalds 18540145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 18550145acc2SLinus Torvalds { 18560145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 18570145acc2SLinus Torvalds while (len--) 18580145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 18590145acc2SLinus Torvalds return end_name_hash(hash); 18600145acc2SLinus Torvalds } 1861ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 18620145acc2SLinus Torvalds 18633ddcd056SLinus Torvalds /* 1864200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1865200e9ef7SLinus Torvalds * one character. 1866200e9ef7SLinus Torvalds */ 1867d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1868200e9ef7SLinus Torvalds { 1869200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1870200e9ef7SLinus Torvalds unsigned long len = 0, c; 1871200e9ef7SLinus Torvalds 1872200e9ef7SLinus Torvalds c = (unsigned char)*name; 1873200e9ef7SLinus Torvalds do { 1874200e9ef7SLinus Torvalds len++; 1875200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1876200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1877200e9ef7SLinus Torvalds } while (c && c != '/'); 1878d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 1879200e9ef7SLinus Torvalds } 1880200e9ef7SLinus Torvalds 1881bfcfaa77SLinus Torvalds #endif 1882bfcfaa77SLinus Torvalds 1883200e9ef7SLinus Torvalds /* 18841da177e4SLinus Torvalds * Name resolution. 1885ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1886ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 18871da177e4SLinus Torvalds * 1888ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1889ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 18901da177e4SLinus Torvalds */ 18916de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 18921da177e4SLinus Torvalds { 18931da177e4SLinus Torvalds int err; 18941da177e4SLinus Torvalds 18951da177e4SLinus Torvalds while (*name=='/') 18961da177e4SLinus Torvalds name++; 18971da177e4SLinus Torvalds if (!*name) 18989e18f10aSAl Viro return 0; 18991da177e4SLinus Torvalds 19001da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 19011da177e4SLinus Torvalds for(;;) { 1902d6bb3e90SLinus Torvalds u64 hash_len; 1903fe479a58SAl Viro int type; 19041da177e4SLinus Torvalds 190552094c8aSAl Viro err = may_lookup(nd); 19061da177e4SLinus Torvalds if (err) 19073595e234SAl Viro return err; 19081da177e4SLinus Torvalds 1909d6bb3e90SLinus Torvalds hash_len = hash_name(name); 19101da177e4SLinus Torvalds 1911fe479a58SAl Viro type = LAST_NORM; 1912d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 1913fe479a58SAl Viro case 2: 1914200e9ef7SLinus Torvalds if (name[1] == '.') { 1915fe479a58SAl Viro type = LAST_DOTDOT; 191616c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 191716c2cd71SAl Viro } 1918fe479a58SAl Viro break; 1919fe479a58SAl Viro case 1: 1920fe479a58SAl Viro type = LAST_DOT; 1921fe479a58SAl Viro } 19225a202bcdSAl Viro if (likely(type == LAST_NORM)) { 19235a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 192416c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 19255a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 1926a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 1927da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 19285a202bcdSAl Viro if (err < 0) 19293595e234SAl Viro return err; 1930d6bb3e90SLinus Torvalds hash_len = this.hash_len; 1931d6bb3e90SLinus Torvalds name = this.name; 19325a202bcdSAl Viro } 19335a202bcdSAl Viro } 1934fe479a58SAl Viro 1935d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 1936d6bb3e90SLinus Torvalds nd->last.name = name; 19375f4a6a69SAl Viro nd->last_type = type; 19385f4a6a69SAl Viro 1939d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 1940d6bb3e90SLinus Torvalds if (!*name) 1941bdf6cbf1SAl Viro goto OK; 1942200e9ef7SLinus Torvalds /* 1943200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1944200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1945200e9ef7SLinus Torvalds */ 1946200e9ef7SLinus Torvalds do { 1947d6bb3e90SLinus Torvalds name++; 1948d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 19498620c238SAl Viro if (unlikely(!*name)) { 19508620c238SAl Viro OK: 1951368ee9baSAl Viro /* pathname body, done */ 19528620c238SAl Viro if (!nd->depth) 19538620c238SAl Viro return 0; 19548620c238SAl Viro name = nd->stack[nd->depth - 1].name; 1955368ee9baSAl Viro /* trailing symlink, done */ 19568620c238SAl Viro if (!name) 19578620c238SAl Viro return 0; 19588620c238SAl Viro /* last component of nested symlink */ 19594693a547SAl Viro err = walk_component(nd, WALK_GET | WALK_PUT); 19608620c238SAl Viro } else { 19614693a547SAl Viro err = walk_component(nd, WALK_GET); 19628620c238SAl Viro } 1963ce57dfc1SAl Viro if (err < 0) 19643595e234SAl Viro return err; 1965fe479a58SAl Viro 1966ce57dfc1SAl Viro if (err) { 1967626de996SAl Viro const char *s = get_link(nd); 19685a460275SAl Viro 1969a1c83681SViresh Kumar if (IS_ERR(s)) 19703595e234SAl Viro return PTR_ERR(s); 1971172a39a0SAl Viro err = 0; 197212b09578SAl Viro if (unlikely(!s)) { 197312b09578SAl Viro /* jumped */ 1974b9ff4429SAl Viro put_link(nd); 197512b09578SAl Viro } else { 1976071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 197732cd7468SAl Viro name = s; 19789e18f10aSAl Viro continue; 197948c8b0c5SAl Viro } 198031e6b01fSNick Piggin } 198197242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 198297242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 198397242f99SAl Viro if (unlazy_walk(nd, NULL, 0)) 198497242f99SAl Viro return -ECHILD; 198597242f99SAl Viro } 19863595e234SAl Viro return -ENOTDIR; 19875f4a6a69SAl Viro } 1988ce57dfc1SAl Viro } 198997242f99SAl Viro } 19901da177e4SLinus Torvalds 1991c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 199231e6b01fSNick Piggin { 199331e6b01fSNick Piggin int retval = 0; 1994c8a53ee5SAl Viro const char *s = nd->name->name; 199531e6b01fSNick Piggin 199631e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 1997980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 199831e6b01fSNick Piggin nd->depth = 0; 19995b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2000b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2001b18825a7SDavid Howells struct inode *inode = root->d_inode; 2002fd2f7cb5SAl Viro if (*s) { 200344b1d530SMiklos Szeredi if (!d_can_lookup(root)) 2004368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 20055b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 20065b6ca027SAl Viro if (retval) 2007368ee9baSAl Viro return ERR_PTR(retval); 200873d049a4SAl Viro } 20095b6ca027SAl Viro nd->path = nd->root; 20105b6ca027SAl Viro nd->inode = inode; 20115b6ca027SAl Viro if (flags & LOOKUP_RCU) { 20128b61e74fSAl Viro rcu_read_lock(); 20135b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 20148f47a016SAl Viro nd->root_seq = nd->seq; 201548a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 20165b6ca027SAl Viro } else { 20175b6ca027SAl Viro path_get(&nd->path); 20185b6ca027SAl Viro } 2019368ee9baSAl Viro return s; 20205b6ca027SAl Viro } 20215b6ca027SAl Viro 202231e6b01fSNick Piggin nd->root.mnt = NULL; 2023248fb5b9SAl Viro nd->path.mnt = NULL; 2024248fb5b9SAl Viro nd->path.dentry = NULL; 202531e6b01fSNick Piggin 202648a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 2027fd2f7cb5SAl Viro if (*s == '/') { 20289e6697e2SAl Viro if (flags & LOOKUP_RCU) 20298b61e74fSAl Viro rcu_read_lock(); 2030e41f7d4eSAl Viro set_root(nd); 2031248fb5b9SAl Viro if (likely(!nd_jump_root(nd))) 2032ef55d917SAl Viro return s; 2033ef55d917SAl Viro nd->root.mnt = NULL; 2034ef55d917SAl Viro rcu_read_unlock(); 2035ef55d917SAl Viro return ERR_PTR(-ECHILD); 2036c8a53ee5SAl Viro } else if (nd->dfd == AT_FDCWD) { 2037e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 203831e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2039c28cc364SNick Piggin unsigned seq; 204031e6b01fSNick Piggin 20418b61e74fSAl Viro rcu_read_lock(); 204231e6b01fSNick Piggin 2043c28cc364SNick Piggin do { 2044c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 204531e6b01fSNick Piggin nd->path = fs->pwd; 2046ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2047c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2048c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2049e41f7d4eSAl Viro } else { 2050e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2051ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2052e41f7d4eSAl Viro } 2053ef55d917SAl Viro return s; 205431e6b01fSNick Piggin } else { 2055582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2056c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 205731e6b01fSNick Piggin struct dentry *dentry; 205831e6b01fSNick Piggin 20592903ff01SAl Viro if (!f.file) 2060368ee9baSAl Viro return ERR_PTR(-EBADF); 206131e6b01fSNick Piggin 20622903ff01SAl Viro dentry = f.file->f_path.dentry; 206331e6b01fSNick Piggin 2064fd2f7cb5SAl Viro if (*s) { 206544b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 20662903ff01SAl Viro fdput(f); 2067368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2068f52e0c11SAl Viro } 20692903ff01SAl Viro } 20702903ff01SAl Viro 20712903ff01SAl Viro nd->path = f.file->f_path; 2072e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 20738b61e74fSAl Viro rcu_read_lock(); 207434a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 207534a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 20765590ff0dSUlrich Drepper } else { 20772903ff01SAl Viro path_get(&nd->path); 207834a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 20791da177e4SLinus Torvalds } 208034a26b99SAl Viro fdput(f); 2081368ee9baSAl Viro return s; 2082e41f7d4eSAl Viro } 20839b4a9b14SAl Viro } 20849b4a9b14SAl Viro 20853bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 208695fa25d9SAl Viro { 208795fa25d9SAl Viro const char *s; 2088fec2fa24SAl Viro int error = may_follow_link(nd); 2089deb106c6SAl Viro if (unlikely(error)) 20903bdba28bSAl Viro return ERR_PTR(error); 209195fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2092fab51e8aSAl Viro nd->stack[0].name = NULL; 20933b2e7f75SAl Viro s = get_link(nd); 2094deb106c6SAl Viro return s ? s : ""; 209595fa25d9SAl Viro } 209695fa25d9SAl Viro 2097caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2098bd92d7feSAl Viro { 2099bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2100bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2101bd92d7feSAl Viro 2102bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 2103deb106c6SAl Viro return walk_component(nd, 21044693a547SAl Viro nd->flags & LOOKUP_FOLLOW 21054693a547SAl Viro ? nd->depth 21064693a547SAl Viro ? WALK_PUT | WALK_GET 21074693a547SAl Viro : WALK_GET 21084693a547SAl Viro : 0); 2109bd92d7feSAl Viro } 2110bd92d7feSAl Viro 21119b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2112c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 21139b4a9b14SAl Viro { 2114c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2115bd92d7feSAl Viro int err; 211631e6b01fSNick Piggin 2117368ee9baSAl Viro if (IS_ERR(s)) 2118368ee9baSAl Viro return PTR_ERR(s); 21193bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 21203bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 21213bdba28bSAl Viro s = trailing_symlink(nd); 21223bdba28bSAl Viro if (IS_ERR(s)) { 21233bdba28bSAl Viro err = PTR_ERR(s); 21246d7b5aaeSAl Viro break; 2125bd92d7feSAl Viro } 2126bd92d7feSAl Viro } 21279f1fafeeSAl Viro if (!err) 21289f1fafeeSAl Viro err = complete_walk(nd); 2129bd92d7feSAl Viro 2130deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2131deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2132bd23a539SAl Viro err = -ENOTDIR; 2133625b6d10SAl Viro if (!err) { 2134625b6d10SAl Viro *path = nd->path; 2135625b6d10SAl Viro nd->path.mnt = NULL; 2136625b6d10SAl Viro nd->path.dentry = NULL; 2137625b6d10SAl Viro } 2138deb106c6SAl Viro terminate_walk(nd); 2139bd92d7feSAl Viro return err; 214031e6b01fSNick Piggin } 214131e6b01fSNick Piggin 2142625b6d10SAl Viro static int filename_lookup(int dfd, struct filename *name, unsigned flags, 21439ad1aaa6SAl Viro struct path *path, struct path *root) 2144873f1eedSJeff Layton { 2145894bc8c4SAl Viro int retval; 21469883d185SAl Viro struct nameidata nd; 2147abc9f5beSAl Viro if (IS_ERR(name)) 2148abc9f5beSAl Viro return PTR_ERR(name); 21499ad1aaa6SAl Viro if (unlikely(root)) { 21509ad1aaa6SAl Viro nd.root = *root; 21519ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 21529ad1aaa6SAl Viro } 21539883d185SAl Viro set_nameidata(&nd, dfd, name); 2154c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2155873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2156c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2157873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2158c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2159873f1eedSJeff Layton 2160873f1eedSJeff Layton if (likely(!retval)) 2161625b6d10SAl Viro audit_inode(name, path->dentry, flags & LOOKUP_PARENT); 21629883d185SAl Viro restore_nameidata(); 2163e4bd1c1aSAl Viro putname(name); 2164873f1eedSJeff Layton return retval; 2165873f1eedSJeff Layton } 2166873f1eedSJeff Layton 21678bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2168c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2169391172c4SAl Viro struct path *parent) 21708bcb77faSAl Viro { 2171c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2172368ee9baSAl Viro int err; 2173368ee9baSAl Viro if (IS_ERR(s)) 2174368ee9baSAl Viro return PTR_ERR(s); 2175368ee9baSAl Viro err = link_path_walk(s, nd); 21768bcb77faSAl Viro if (!err) 21778bcb77faSAl Viro err = complete_walk(nd); 2178391172c4SAl Viro if (!err) { 2179391172c4SAl Viro *parent = nd->path; 2180391172c4SAl Viro nd->path.mnt = NULL; 2181391172c4SAl Viro nd->path.dentry = NULL; 2182391172c4SAl Viro } 2183deb106c6SAl Viro terminate_walk(nd); 21848bcb77faSAl Viro return err; 21858bcb77faSAl Viro } 21868bcb77faSAl Viro 21875c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2188391172c4SAl Viro unsigned int flags, struct path *parent, 2189391172c4SAl Viro struct qstr *last, int *type) 21908bcb77faSAl Viro { 21918bcb77faSAl Viro int retval; 21929883d185SAl Viro struct nameidata nd; 21938bcb77faSAl Viro 21945c31b6ceSAl Viro if (IS_ERR(name)) 21955c31b6ceSAl Viro return name; 21969883d185SAl Viro set_nameidata(&nd, dfd, name); 2197c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 21988bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2199c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 22008bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2201c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2202391172c4SAl Viro if (likely(!retval)) { 2203391172c4SAl Viro *last = nd.last; 2204391172c4SAl Viro *type = nd.last_type; 2205391172c4SAl Viro audit_inode(name, parent->dentry, LOOKUP_PARENT); 22065c31b6ceSAl Viro } else { 22075c31b6ceSAl Viro putname(name); 22085c31b6ceSAl Viro name = ERR_PTR(retval); 2209391172c4SAl Viro } 22109883d185SAl Viro restore_nameidata(); 22115c31b6ceSAl Viro return name; 22128bcb77faSAl Viro } 22138bcb77faSAl Viro 221479714f72SAl Viro /* does lookup, returns the object with parent locked */ 221579714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 22165590ff0dSUlrich Drepper { 22175c31b6ceSAl Viro struct filename *filename; 22185c31b6ceSAl Viro struct dentry *d; 2219391172c4SAl Viro struct qstr last; 2220391172c4SAl Viro int type; 222151689104SPaul Moore 22225c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 22235c31b6ceSAl Viro &last, &type); 222451689104SPaul Moore if (IS_ERR(filename)) 222551689104SPaul Moore return ERR_CAST(filename); 22265c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2227391172c4SAl Viro path_put(path); 22285c31b6ceSAl Viro putname(filename); 22295c31b6ceSAl Viro return ERR_PTR(-EINVAL); 223079714f72SAl Viro } 2231391172c4SAl Viro mutex_lock_nested(&path->dentry->d_inode->i_mutex, I_MUTEX_PARENT); 2232391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 223379714f72SAl Viro if (IS_ERR(d)) { 2234391172c4SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 2235391172c4SAl Viro path_put(path); 223679714f72SAl Viro } 223751689104SPaul Moore putname(filename); 223879714f72SAl Viro return d; 22395590ff0dSUlrich Drepper } 22405590ff0dSUlrich Drepper 2241d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2242d1811465SAl Viro { 2243abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2244abc9f5beSAl Viro flags, path, NULL); 2245d1811465SAl Viro } 22464d359507SAl Viro EXPORT_SYMBOL(kern_path); 2247d1811465SAl Viro 224816f18200SJosef 'Jeff' Sipek /** 224916f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 225016f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 225116f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 225216f18200SJosef 'Jeff' Sipek * @name: pointer to file name 225316f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2254e0a01249SAl Viro * @path: pointer to struct path to fill 225516f18200SJosef 'Jeff' Sipek */ 225616f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 225716f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2258e0a01249SAl Viro struct path *path) 225916f18200SJosef 'Jeff' Sipek { 22609ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 22619ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2262abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2263abc9f5beSAl Viro flags , path, &root); 226416f18200SJosef 'Jeff' Sipek } 22654d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 226616f18200SJosef 'Jeff' Sipek 2267eead1911SChristoph Hellwig /** 2268a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2269eead1911SChristoph Hellwig * @name: pathname component to lookup 2270eead1911SChristoph Hellwig * @base: base directory to lookup from 2271eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2272eead1911SChristoph Hellwig * 2273a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 22749e7543e9SAl Viro * not be called by generic code. 2275bbddca8eSNeilBrown * 2276bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2277eead1911SChristoph Hellwig */ 2278057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2279057f6c01SJames Morris { 2280057f6c01SJames Morris struct qstr this; 22816a96ba54SAl Viro unsigned int c; 2282cda309deSMiklos Szeredi int err; 2283057f6c01SJames Morris 22842f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 22852f9092e1SDavid Woodhouse 22866a96ba54SAl Viro this.name = name; 22876a96ba54SAl Viro this.len = len; 22880145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 22896a96ba54SAl Viro if (!len) 22906a96ba54SAl Viro return ERR_PTR(-EACCES); 22916a96ba54SAl Viro 229221d8a15aSAl Viro if (unlikely(name[0] == '.')) { 229321d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 229421d8a15aSAl Viro return ERR_PTR(-EACCES); 229521d8a15aSAl Viro } 229621d8a15aSAl Viro 22976a96ba54SAl Viro while (len--) { 22986a96ba54SAl Viro c = *(const unsigned char *)name++; 22996a96ba54SAl Viro if (c == '/' || c == '\0') 23006a96ba54SAl Viro return ERR_PTR(-EACCES); 23016a96ba54SAl Viro } 23025a202bcdSAl Viro /* 23035a202bcdSAl Viro * See if the low-level filesystem might want 23045a202bcdSAl Viro * to use its own hash.. 23055a202bcdSAl Viro */ 23065a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2307da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 23085a202bcdSAl Viro if (err < 0) 23095a202bcdSAl Viro return ERR_PTR(err); 23105a202bcdSAl Viro } 2311eead1911SChristoph Hellwig 2312cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2313cda309deSMiklos Szeredi if (err) 2314cda309deSMiklos Szeredi return ERR_PTR(err); 2315cda309deSMiklos Szeredi 231672bd866aSAl Viro return __lookup_hash(&this, base, 0); 2317057f6c01SJames Morris } 23184d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2319057f6c01SJames Morris 2320bbddca8eSNeilBrown /** 2321bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2322bbddca8eSNeilBrown * @name: pathname component to lookup 2323bbddca8eSNeilBrown * @base: base directory to lookup from 2324bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2325bbddca8eSNeilBrown * 2326bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2327bbddca8eSNeilBrown * not be called by generic code. 2328bbddca8eSNeilBrown * 2329bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2330bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2331bbddca8eSNeilBrown */ 2332bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2333bbddca8eSNeilBrown struct dentry *base, int len) 2334bbddca8eSNeilBrown { 2335bbddca8eSNeilBrown struct qstr this; 2336bbddca8eSNeilBrown unsigned int c; 2337bbddca8eSNeilBrown int err; 2338bbddca8eSNeilBrown struct dentry *ret; 2339bbddca8eSNeilBrown 2340bbddca8eSNeilBrown this.name = name; 2341bbddca8eSNeilBrown this.len = len; 2342bbddca8eSNeilBrown this.hash = full_name_hash(name, len); 2343bbddca8eSNeilBrown if (!len) 2344bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2345bbddca8eSNeilBrown 2346bbddca8eSNeilBrown if (unlikely(name[0] == '.')) { 2347bbddca8eSNeilBrown if (len < 2 || (len == 2 && name[1] == '.')) 2348bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2349bbddca8eSNeilBrown } 2350bbddca8eSNeilBrown 2351bbddca8eSNeilBrown while (len--) { 2352bbddca8eSNeilBrown c = *(const unsigned char *)name++; 2353bbddca8eSNeilBrown if (c == '/' || c == '\0') 2354bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2355bbddca8eSNeilBrown } 2356bbddca8eSNeilBrown /* 2357bbddca8eSNeilBrown * See if the low-level filesystem might want 2358bbddca8eSNeilBrown * to use its own hash.. 2359bbddca8eSNeilBrown */ 2360bbddca8eSNeilBrown if (base->d_flags & DCACHE_OP_HASH) { 2361bbddca8eSNeilBrown int err = base->d_op->d_hash(base, &this); 2362bbddca8eSNeilBrown if (err < 0) 2363bbddca8eSNeilBrown return ERR_PTR(err); 2364bbddca8eSNeilBrown } 2365bbddca8eSNeilBrown 2366bbddca8eSNeilBrown err = inode_permission(base->d_inode, MAY_EXEC); 2367bbddca8eSNeilBrown if (err) 2368bbddca8eSNeilBrown return ERR_PTR(err); 2369bbddca8eSNeilBrown 2370bbddca8eSNeilBrown /* 2371bbddca8eSNeilBrown * __d_lookup() is used to try to get a quick answer and avoid the 2372bbddca8eSNeilBrown * mutex. A false-negative does no harm. 2373bbddca8eSNeilBrown */ 2374bbddca8eSNeilBrown ret = __d_lookup(base, &this); 2375bbddca8eSNeilBrown if (ret && unlikely(ret->d_flags & DCACHE_OP_REVALIDATE)) { 2376bbddca8eSNeilBrown dput(ret); 2377bbddca8eSNeilBrown ret = NULL; 2378bbddca8eSNeilBrown } 2379bbddca8eSNeilBrown if (ret) 2380bbddca8eSNeilBrown return ret; 2381bbddca8eSNeilBrown 2382bbddca8eSNeilBrown mutex_lock(&base->d_inode->i_mutex); 2383bbddca8eSNeilBrown ret = __lookup_hash(&this, base, 0); 2384bbddca8eSNeilBrown mutex_unlock(&base->d_inode->i_mutex); 2385bbddca8eSNeilBrown return ret; 2386bbddca8eSNeilBrown } 2387bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2388bbddca8eSNeilBrown 23891fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 23901fa1e7f6SAndy Whitcroft struct path *path, int *empty) 23911da177e4SLinus Torvalds { 2392abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2393abc9f5beSAl Viro flags, path, NULL); 23941da177e4SLinus Torvalds } 2395b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 23961fa1e7f6SAndy Whitcroft 2397873f1eedSJeff Layton /* 2398873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2399873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2400873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2401873f1eedSJeff Layton * path-walking is complete. 2402873f1eedSJeff Layton */ 2403a2ec4a2dSAl Viro static inline struct filename * 2404f5beed75SAl Viro user_path_parent(int dfd, const char __user *path, 2405f5beed75SAl Viro struct path *parent, 2406f5beed75SAl Viro struct qstr *last, 2407f5beed75SAl Viro int *type, 24089e790bd6SJeff Layton unsigned int flags) 24092ad94ae6SAl Viro { 24109e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 24115c31b6ceSAl Viro return filename_parentat(dfd, getname(path), flags & LOOKUP_REVAL, 24125c31b6ceSAl Viro parent, last, type); 24132ad94ae6SAl Viro } 24142ad94ae6SAl Viro 24158033426eSJeff Layton /** 2416197df04cSAl Viro * mountpoint_last - look up last component for umount 24178033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 24188033426eSJeff Layton * @path: pointer to container for result 24198033426eSJeff Layton * 24208033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 24218033426eSJeff Layton * need to resolve the path without doing any revalidation. 24228033426eSJeff Layton * 24238033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 24248033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 24258033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 24268033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 24278033426eSJeff Layton * bogus and it doesn't exist. 24288033426eSJeff Layton * 24298033426eSJeff Layton * Returns: 24308033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 24318033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 24328033426eSJeff Layton * put in this case. 24338033426eSJeff Layton * 24348033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 24358033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 24368033426eSJeff Layton * The nd->path reference will also be put. 24378033426eSJeff Layton * 24388033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 24398033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 24408033426eSJeff Layton * to the link, and nd->path will *not* be put. 24418033426eSJeff Layton */ 24428033426eSJeff Layton static int 2443197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 24448033426eSJeff Layton { 24458033426eSJeff Layton int error = 0; 24468033426eSJeff Layton struct dentry *dentry; 24478033426eSJeff Layton struct dentry *dir = nd->path.dentry; 24488033426eSJeff Layton 244935759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 245035759521SAl Viro if (nd->flags & LOOKUP_RCU) { 24516e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 2452deb106c6SAl Viro return -ECHILD; 24538033426eSJeff Layton } 24548033426eSJeff Layton 24558033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 24568033426eSJeff Layton 24578033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 24588033426eSJeff Layton error = handle_dots(nd, nd->last_type); 245935759521SAl Viro if (error) 2460deb106c6SAl Viro return error; 24618033426eSJeff Layton dentry = dget(nd->path.dentry); 246235759521SAl Viro goto done; 24638033426eSJeff Layton } 24648033426eSJeff Layton 24658033426eSJeff Layton mutex_lock(&dir->d_inode->i_mutex); 24668033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 24678033426eSJeff Layton if (!dentry) { 24688033426eSJeff Layton /* 24698033426eSJeff Layton * No cached dentry. Mounted dentries are pinned in the cache, 24708033426eSJeff Layton * so that means that this dentry is probably a symlink or the 24718033426eSJeff Layton * path doesn't actually point to a mounted dentry. 24728033426eSJeff Layton */ 24738033426eSJeff Layton dentry = d_alloc(dir, &nd->last); 24748033426eSJeff Layton if (!dentry) { 2475bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 2476deb106c6SAl Viro return -ENOMEM; 24778033426eSJeff Layton } 247835759521SAl Viro dentry = lookup_real(dir->d_inode, dentry, nd->flags); 2479bcceeebaSDave Jones if (IS_ERR(dentry)) { 2480bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 2481deb106c6SAl Viro return PTR_ERR(dentry); 24828033426eSJeff Layton } 2483bcceeebaSDave Jones } 24848033426eSJeff Layton mutex_unlock(&dir->d_inode->i_mutex); 24858033426eSJeff Layton 248635759521SAl Viro done: 2487698934dfSDavid Howells if (d_is_negative(dentry)) { 24888033426eSJeff Layton dput(dentry); 2489deb106c6SAl Viro return -ENOENT; 249035759521SAl Viro } 2491191d7f73SAl Viro if (nd->depth) 2492191d7f73SAl Viro put_link(nd); 24938033426eSJeff Layton path->dentry = dentry; 2494295dc39dSVasily Averin path->mnt = nd->path.mnt; 2495181548c0SAl Viro error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW, 2496181548c0SAl Viro d_backing_inode(dentry), 0); 2497deb106c6SAl Viro if (unlikely(error)) 2498d63ff28fSAl Viro return error; 2499295dc39dSVasily Averin mntget(path->mnt); 25008033426eSJeff Layton follow_mount(path); 2501deb106c6SAl Viro return 0; 25028033426eSJeff Layton } 25038033426eSJeff Layton 25048033426eSJeff Layton /** 2505197df04cSAl Viro * path_mountpoint - look up a path to be umounted 25062a78b857SMasanari Iida * @nd: lookup context 25078033426eSJeff Layton * @flags: lookup flags 2508c8a53ee5SAl Viro * @path: pointer to container for result 25098033426eSJeff Layton * 25108033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2511606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 25128033426eSJeff Layton */ 25138033426eSJeff Layton static int 2514c8a53ee5SAl Viro path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) 25158033426eSJeff Layton { 2516c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2517368ee9baSAl Viro int err; 2518368ee9baSAl Viro if (IS_ERR(s)) 2519368ee9baSAl Viro return PTR_ERR(s); 25203bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 25213bdba28bSAl Viro (err = mountpoint_last(nd, path)) > 0) { 25223bdba28bSAl Viro s = trailing_symlink(nd); 25233bdba28bSAl Viro if (IS_ERR(s)) { 25243bdba28bSAl Viro err = PTR_ERR(s); 25258033426eSJeff Layton break; 25268033426eSJeff Layton } 25273bdba28bSAl Viro } 2528deb106c6SAl Viro terminate_walk(nd); 25298033426eSJeff Layton return err; 25308033426eSJeff Layton } 25318033426eSJeff Layton 25322d864651SAl Viro static int 2533668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 25342d864651SAl Viro unsigned int flags) 25352d864651SAl Viro { 25369883d185SAl Viro struct nameidata nd; 2537cbaab2dbSAl Viro int error; 2538668696dcSAl Viro if (IS_ERR(name)) 2539668696dcSAl Viro return PTR_ERR(name); 25409883d185SAl Viro set_nameidata(&nd, dfd, name); 2541c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); 25422d864651SAl Viro if (unlikely(error == -ECHILD)) 2543c8a53ee5SAl Viro error = path_mountpoint(&nd, flags, path); 25442d864651SAl Viro if (unlikely(error == -ESTALE)) 2545c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); 25462d864651SAl Viro if (likely(!error)) 2547668696dcSAl Viro audit_inode(name, path->dentry, 0); 25489883d185SAl Viro restore_nameidata(); 2549668696dcSAl Viro putname(name); 25502d864651SAl Viro return error; 25512d864651SAl Viro } 25522d864651SAl Viro 25538033426eSJeff Layton /** 2554197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 25558033426eSJeff Layton * @dfd: directory file descriptor 25568033426eSJeff Layton * @name: pathname from userland 25578033426eSJeff Layton * @flags: lookup flags 25588033426eSJeff Layton * @path: pointer to container to hold result 25598033426eSJeff Layton * 25608033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 25618033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 25628033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 25638033426eSJeff Layton * and avoid revalidating the last component. 25648033426eSJeff Layton * 25658033426eSJeff Layton * Returns 0 and populates "path" on success. 25668033426eSJeff Layton */ 25678033426eSJeff Layton int 2568197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 25698033426eSJeff Layton struct path *path) 25708033426eSJeff Layton { 2571cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 25728033426eSJeff Layton } 25738033426eSJeff Layton 25742d864651SAl Viro int 25752d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 25762d864651SAl Viro unsigned int flags) 25772d864651SAl Viro { 2578cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 25792d864651SAl Viro } 25802d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 25812d864651SAl Viro 2582cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 25831da177e4SLinus Torvalds { 25848e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2585da9592edSDavid Howells 25868e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 25871da177e4SLinus Torvalds return 0; 25888e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 25891da177e4SLinus Torvalds return 0; 259023adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 25911da177e4SLinus Torvalds } 2592cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 25931da177e4SLinus Torvalds 25941da177e4SLinus Torvalds /* 25951da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 25961da177e4SLinus Torvalds * whether the type of victim is right. 25971da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 25981da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 25991da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 26001da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 26011da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 26021da177e4SLinus Torvalds * a. be owner of dir, or 26031da177e4SLinus Torvalds * b. be owner of victim, or 26041da177e4SLinus Torvalds * c. have CAP_FOWNER capability 26051da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 26061da177e4SLinus Torvalds * links pointing to it. 26071da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 26081da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 26091da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 26101da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 26111da177e4SLinus Torvalds * nfs_async_unlink(). 26121da177e4SLinus Torvalds */ 2613b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 26141da177e4SLinus Torvalds { 261563afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 26161da177e4SLinus Torvalds int error; 26171da177e4SLinus Torvalds 2618b18825a7SDavid Howells if (d_is_negative(victim)) 26191da177e4SLinus Torvalds return -ENOENT; 2620b18825a7SDavid Howells BUG_ON(!inode); 26211da177e4SLinus Torvalds 26221da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 26234fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 26241da177e4SLinus Torvalds 2625f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 26261da177e4SLinus Torvalds if (error) 26271da177e4SLinus Torvalds return error; 26281da177e4SLinus Torvalds if (IS_APPEND(dir)) 26291da177e4SLinus Torvalds return -EPERM; 2630b18825a7SDavid Howells 2631b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2632b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 26331da177e4SLinus Torvalds return -EPERM; 26341da177e4SLinus Torvalds if (isdir) { 263544b1d530SMiklos Szeredi if (!d_is_dir(victim)) 26361da177e4SLinus Torvalds return -ENOTDIR; 26371da177e4SLinus Torvalds if (IS_ROOT(victim)) 26381da177e4SLinus Torvalds return -EBUSY; 263944b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 26401da177e4SLinus Torvalds return -EISDIR; 26411da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 26421da177e4SLinus Torvalds return -ENOENT; 26431da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 26441da177e4SLinus Torvalds return -EBUSY; 26451da177e4SLinus Torvalds return 0; 26461da177e4SLinus Torvalds } 26471da177e4SLinus Torvalds 26481da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 26491da177e4SLinus Torvalds * dir. 26501da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 26511da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 26521da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 26531da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 26541da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 26551da177e4SLinus Torvalds */ 2656a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 26571da177e4SLinus Torvalds { 265814e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 26591da177e4SLinus Torvalds if (child->d_inode) 26601da177e4SLinus Torvalds return -EEXIST; 26611da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 26621da177e4SLinus Torvalds return -ENOENT; 2663f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 26641da177e4SLinus Torvalds } 26651da177e4SLinus Torvalds 26661da177e4SLinus Torvalds /* 26671da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 26681da177e4SLinus Torvalds */ 26691da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 26701da177e4SLinus Torvalds { 26711da177e4SLinus Torvalds struct dentry *p; 26721da177e4SLinus Torvalds 26731da177e4SLinus Torvalds if (p1 == p2) { 2674f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 26751da177e4SLinus Torvalds return NULL; 26761da177e4SLinus Torvalds } 26771da177e4SLinus Torvalds 2678a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 26791da177e4SLinus Torvalds 2680e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2681e2761a11SOGAWA Hirofumi if (p) { 2682f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2683f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 26841da177e4SLinus Torvalds return p; 26851da177e4SLinus Torvalds } 26861da177e4SLinus Torvalds 2687e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2688e2761a11SOGAWA Hirofumi if (p) { 2689f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2690f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 26911da177e4SLinus Torvalds return p; 26921da177e4SLinus Torvalds } 26931da177e4SLinus Torvalds 2694f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2695d1b72cc6SMiklos Szeredi mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); 26961da177e4SLinus Torvalds return NULL; 26971da177e4SLinus Torvalds } 26984d359507SAl Viro EXPORT_SYMBOL(lock_rename); 26991da177e4SLinus Torvalds 27001da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 27011da177e4SLinus Torvalds { 27021b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 27031da177e4SLinus Torvalds if (p1 != p2) { 27041b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2705a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 27061da177e4SLinus Torvalds } 27071da177e4SLinus Torvalds } 27084d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 27091da177e4SLinus Torvalds 27104acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2711312b63fbSAl Viro bool want_excl) 27121da177e4SLinus Torvalds { 2713a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 27141da177e4SLinus Torvalds if (error) 27151da177e4SLinus Torvalds return error; 27161da177e4SLinus Torvalds 2717acfa4380SAl Viro if (!dir->i_op->create) 27181da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 27191da177e4SLinus Torvalds mode &= S_IALLUGO; 27201da177e4SLinus Torvalds mode |= S_IFREG; 27211da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 27221da177e4SLinus Torvalds if (error) 27231da177e4SLinus Torvalds return error; 2724312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2725a74574aaSStephen Smalley if (!error) 2726f38aa942SAmy Griffis fsnotify_create(dir, dentry); 27271da177e4SLinus Torvalds return error; 27281da177e4SLinus Torvalds } 27294d359507SAl Viro EXPORT_SYMBOL(vfs_create); 27301da177e4SLinus Torvalds 273173d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 27321da177e4SLinus Torvalds { 27333fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 27341da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 27351da177e4SLinus Torvalds int error; 27361da177e4SLinus Torvalds 27371da177e4SLinus Torvalds if (!inode) 27381da177e4SLinus Torvalds return -ENOENT; 27391da177e4SLinus Torvalds 2740c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2741c8fe8f30SChristoph Hellwig case S_IFLNK: 27421da177e4SLinus Torvalds return -ELOOP; 2743c8fe8f30SChristoph Hellwig case S_IFDIR: 2744c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 27451da177e4SLinus Torvalds return -EISDIR; 2746c8fe8f30SChristoph Hellwig break; 2747c8fe8f30SChristoph Hellwig case S_IFBLK: 2748c8fe8f30SChristoph Hellwig case S_IFCHR: 27493fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 27501da177e4SLinus Torvalds return -EACCES; 2751c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2752c8fe8f30SChristoph Hellwig case S_IFIFO: 2753c8fe8f30SChristoph Hellwig case S_IFSOCK: 27541da177e4SLinus Torvalds flag &= ~O_TRUNC; 2755c8fe8f30SChristoph Hellwig break; 27564a3fd211SDave Hansen } 2757b41572e9SDave Hansen 275862fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2759b41572e9SDave Hansen if (error) 2760b41572e9SDave Hansen return error; 27616146f0d5SMimi Zohar 27621da177e4SLinus Torvalds /* 27631da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 27641da177e4SLinus Torvalds */ 27651da177e4SLinus Torvalds if (IS_APPEND(inode)) { 27668737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 27677715b521SAl Viro return -EPERM; 27681da177e4SLinus Torvalds if (flag & O_TRUNC) 27697715b521SAl Viro return -EPERM; 27701da177e4SLinus Torvalds } 27711da177e4SLinus Torvalds 27721da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 27732e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 27747715b521SAl Viro return -EPERM; 27751da177e4SLinus Torvalds 2776f3c7691eSJ. Bruce Fields return 0; 27777715b521SAl Viro } 27787715b521SAl Viro 2779e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 27807715b521SAl Viro { 2781e1181ee6SJeff Layton struct path *path = &filp->f_path; 27827715b521SAl Viro struct inode *inode = path->dentry->d_inode; 27837715b521SAl Viro int error = get_write_access(inode); 27841da177e4SLinus Torvalds if (error) 27857715b521SAl Viro return error; 27861da177e4SLinus Torvalds /* 27871da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 27881da177e4SLinus Torvalds */ 2789d7a06983SJeff Layton error = locks_verify_locked(filp); 2790be6d3e56SKentaro Takeda if (!error) 2791ea0d3ab2STetsuo Handa error = security_path_truncate(path); 27921da177e4SLinus Torvalds if (!error) { 27937715b521SAl Viro error = do_truncate(path->dentry, 0, 2794d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2795e1181ee6SJeff Layton filp); 27961da177e4SLinus Torvalds } 27971da177e4SLinus Torvalds put_write_access(inode); 2798acd0c935SMimi Zohar return error; 27991da177e4SLinus Torvalds } 28001da177e4SLinus Torvalds 2801d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2802d57999e1SDave Hansen { 28038a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 28048a5e929dSAl Viro flag--; 2805d57999e1SDave Hansen return flag; 2806d57999e1SDave Hansen } 2807d57999e1SDave Hansen 2808d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2809d18e9008SMiklos Szeredi { 2810d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2811d18e9008SMiklos Szeredi if (error) 2812d18e9008SMiklos Szeredi return error; 2813d18e9008SMiklos Szeredi 2814d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2815d18e9008SMiklos Szeredi if (error) 2816d18e9008SMiklos Szeredi return error; 2817d18e9008SMiklos Szeredi 2818d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2819d18e9008SMiklos Szeredi } 2820d18e9008SMiklos Szeredi 28211acf0af9SDavid Howells /* 28221acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 28231acf0af9SDavid Howells * dentry. 28241acf0af9SDavid Howells * 28251acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 28261acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 28271acf0af9SDavid Howells * 28281acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 28291acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 28301acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 28311acf0af9SDavid Howells * 28321acf0af9SDavid Howells * Returns an error code otherwise. 28331acf0af9SDavid Howells */ 28342675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 283530d90494SAl Viro struct path *path, struct file *file, 2836015c3bbcSMiklos Szeredi const struct open_flags *op, 283764894cf8SAl Viro bool got_write, bool need_lookup, 283847237687SAl Viro int *opened) 2839d18e9008SMiklos Szeredi { 2840d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2841d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2842d18e9008SMiklos Szeredi umode_t mode; 2843d18e9008SMiklos Szeredi int error; 2844d18e9008SMiklos Szeredi int acc_mode; 2845d18e9008SMiklos Szeredi int create_error = 0; 2846d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2847116cc022SMiklos Szeredi bool excl; 2848d18e9008SMiklos Szeredi 2849d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2850d18e9008SMiklos Szeredi 2851d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2852d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 28532675a4ebSAl Viro error = -ENOENT; 2854d18e9008SMiklos Szeredi goto out; 2855d18e9008SMiklos Szeredi } 2856d18e9008SMiklos Szeredi 285762b259d8SMiklos Szeredi mode = op->mode; 2858d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2859d18e9008SMiklos Szeredi mode &= ~current_umask(); 2860d18e9008SMiklos Szeredi 2861116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2862116cc022SMiklos Szeredi if (excl) 2863d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2864d18e9008SMiklos Szeredi 2865d18e9008SMiklos Szeredi /* 2866d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2867d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2868d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2869d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2870d18e9008SMiklos Szeredi * 2871d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2872d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2873d18e9008SMiklos Szeredi */ 287464894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 287564894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 287664894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2877d18e9008SMiklos Szeredi /* 2878d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2879d18e9008SMiklos Szeredi * back to lookup + open 2880d18e9008SMiklos Szeredi */ 2881d18e9008SMiklos Szeredi goto no_open; 2882d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2883d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 288464894cf8SAl Viro create_error = -EROFS; 2885d18e9008SMiklos Szeredi goto no_open; 2886d18e9008SMiklos Szeredi } else { 2887d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 288864894cf8SAl Viro create_error = -EROFS; 2889d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2890d18e9008SMiklos Szeredi } 2891d18e9008SMiklos Szeredi } 2892d18e9008SMiklos Szeredi 2893d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 289438227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2895d18e9008SMiklos Szeredi if (error) { 2896d18e9008SMiklos Szeredi create_error = error; 2897d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2898d18e9008SMiklos Szeredi goto no_open; 2899d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2900d18e9008SMiklos Szeredi } 2901d18e9008SMiklos Szeredi } 2902d18e9008SMiklos Szeredi 2903d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2904d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2905d18e9008SMiklos Szeredi 290630d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 290730d90494SAl Viro file->f_path.mnt = nd->path.mnt; 290830d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 290947237687SAl Viro opened); 2910d9585277SAl Viro if (error < 0) { 2911d9585277SAl Viro if (create_error && error == -ENOENT) 2912d9585277SAl Viro error = create_error; 2913d18e9008SMiklos Szeredi goto out; 2914d18e9008SMiklos Szeredi } 2915d18e9008SMiklos Szeredi 2916d9585277SAl Viro if (error) { /* returned 1, that is */ 291730d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 29182675a4ebSAl Viro error = -EIO; 2919d18e9008SMiklos Szeredi goto out; 2920d18e9008SMiklos Szeredi } 292130d90494SAl Viro if (file->f_path.dentry) { 2922d18e9008SMiklos Szeredi dput(dentry); 292330d90494SAl Viro dentry = file->f_path.dentry; 2924d18e9008SMiklos Szeredi } 292503da633aSAl Viro if (*opened & FILE_CREATED) 292603da633aSAl Viro fsnotify_create(dir, dentry); 292703da633aSAl Viro if (!dentry->d_inode) { 292803da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 292903da633aSAl Viro if (create_error) { 293062b2ce96SSage Weil error = create_error; 293162b2ce96SSage Weil goto out; 293262b2ce96SSage Weil } 293303da633aSAl Viro } else { 293403da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 293503da633aSAl Viro error = -EEXIST; 293603da633aSAl Viro goto out; 293703da633aSAl Viro } 293803da633aSAl Viro } 2939d18e9008SMiklos Szeredi goto looked_up; 2940d18e9008SMiklos Szeredi } 2941d18e9008SMiklos Szeredi 2942d18e9008SMiklos Szeredi /* 2943d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2944d18e9008SMiklos Szeredi * here. 2945d18e9008SMiklos Szeredi */ 294603da633aSAl Viro acc_mode = op->acc_mode; 294703da633aSAl Viro if (*opened & FILE_CREATED) { 294803da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 294903da633aSAl Viro fsnotify_create(dir, dentry); 295062fb4a15SAl Viro acc_mode = 0; 295103da633aSAl Viro } 29522675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 29532675a4ebSAl Viro if (error) 29542675a4ebSAl Viro fput(file); 2955d18e9008SMiklos Szeredi 2956d18e9008SMiklos Szeredi out: 2957d18e9008SMiklos Szeredi dput(dentry); 29582675a4ebSAl Viro return error; 2959d18e9008SMiklos Szeredi 2960d18e9008SMiklos Szeredi no_open: 2961d18e9008SMiklos Szeredi if (need_lookup) { 296272bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2963d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 29642675a4ebSAl Viro return PTR_ERR(dentry); 2965d18e9008SMiklos Szeredi 2966d18e9008SMiklos Szeredi if (create_error) { 2967d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2968d18e9008SMiklos Szeredi 29692675a4ebSAl Viro error = create_error; 2970d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2971d18e9008SMiklos Szeredi if (!dentry->d_inode) 2972d18e9008SMiklos Szeredi goto out; 2973d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2974d18e9008SMiklos Szeredi goto out; 2975d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2976e36cb0b8SDavid Howells d_is_reg(dentry)) { 2977d18e9008SMiklos Szeredi goto out; 2978d18e9008SMiklos Szeredi } 2979d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2980d18e9008SMiklos Szeredi } 2981d18e9008SMiklos Szeredi } 2982d18e9008SMiklos Szeredi looked_up: 2983d18e9008SMiklos Szeredi path->dentry = dentry; 2984d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 29852675a4ebSAl Viro return 1; 2986d18e9008SMiklos Szeredi } 2987d18e9008SMiklos Szeredi 298831e6b01fSNick Piggin /* 29891acf0af9SDavid Howells * Look up and maybe create and open the last component. 2990d58ffd35SMiklos Szeredi * 2991d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2992d58ffd35SMiklos Szeredi * 29931acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 29941acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 29951acf0af9SDavid Howells * 29961acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 29971acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 29981acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 29991acf0af9SDavid Howells * specified then a negative dentry may be returned. 30001acf0af9SDavid Howells * 30011acf0af9SDavid Howells * An error code is returned otherwise. 30021acf0af9SDavid Howells * 30031acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 30041acf0af9SDavid Howells * cleared otherwise prior to returning. 3005d58ffd35SMiklos Szeredi */ 30062675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 300730d90494SAl Viro struct file *file, 3008d58ffd35SMiklos Szeredi const struct open_flags *op, 300964894cf8SAl Viro bool got_write, int *opened) 3010d58ffd35SMiklos Szeredi { 3011d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 301254ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 3013d58ffd35SMiklos Szeredi struct dentry *dentry; 3014d58ffd35SMiklos Szeredi int error; 301554ef4872SMiklos Szeredi bool need_lookup; 3016d58ffd35SMiklos Szeredi 301747237687SAl Viro *opened &= ~FILE_CREATED; 3018201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 3019d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 30202675a4ebSAl Viro return PTR_ERR(dentry); 3021d58ffd35SMiklos Szeredi 3022d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3023d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 3024d18e9008SMiklos Szeredi goto out_no_open; 3025d18e9008SMiklos Szeredi 3026d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 302764894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 302847237687SAl Viro need_lookup, opened); 3029d18e9008SMiklos Szeredi } 3030d18e9008SMiklos Szeredi 303154ef4872SMiklos Szeredi if (need_lookup) { 303254ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 303354ef4872SMiklos Szeredi 303472bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 303554ef4872SMiklos Szeredi if (IS_ERR(dentry)) 30362675a4ebSAl Viro return PTR_ERR(dentry); 303754ef4872SMiklos Szeredi } 303854ef4872SMiklos Szeredi 3039d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 3040d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 3041d58ffd35SMiklos Szeredi umode_t mode = op->mode; 3042d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 3043d58ffd35SMiklos Szeredi mode &= ~current_umask(); 3044d58ffd35SMiklos Szeredi /* 3045d58ffd35SMiklos Szeredi * This write is needed to ensure that a 3046d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 3047d58ffd35SMiklos Szeredi * the time when the file is created and when 3048d58ffd35SMiklos Szeredi * a permanent write count is taken through 3049015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 3050d58ffd35SMiklos Szeredi */ 305164894cf8SAl Viro if (!got_write) { 305264894cf8SAl Viro error = -EROFS; 3053d58ffd35SMiklos Szeredi goto out_dput; 305464894cf8SAl Viro } 305547237687SAl Viro *opened |= FILE_CREATED; 3056d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 3057d58ffd35SMiklos Szeredi if (error) 3058d58ffd35SMiklos Szeredi goto out_dput; 3059312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 3060312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 3061d58ffd35SMiklos Szeredi if (error) 3062d58ffd35SMiklos Szeredi goto out_dput; 3063d58ffd35SMiklos Szeredi } 3064d18e9008SMiklos Szeredi out_no_open: 3065d58ffd35SMiklos Szeredi path->dentry = dentry; 3066d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 30672675a4ebSAl Viro return 1; 3068d58ffd35SMiklos Szeredi 3069d58ffd35SMiklos Szeredi out_dput: 3070d58ffd35SMiklos Szeredi dput(dentry); 30712675a4ebSAl Viro return error; 3072d58ffd35SMiklos Szeredi } 3073d58ffd35SMiklos Szeredi 3074d58ffd35SMiklos Szeredi /* 3075fe2d35ffSAl Viro * Handle the last step of open() 307631e6b01fSNick Piggin */ 3077896475d5SAl Viro static int do_last(struct nameidata *nd, 307830d90494SAl Viro struct file *file, const struct open_flags *op, 307976ae2a5aSAl Viro int *opened) 3080fb1cc555SAl Viro { 3081a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3082ca344a89SAl Viro int open_flag = op->open_flag; 308377d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 308464894cf8SAl Viro bool got_write = false; 3085bcda7652SAl Viro int acc_mode = op->acc_mode; 3086254cf582SAl Viro unsigned seq; 3087a1eb3315SMiklos Szeredi struct inode *inode; 308816b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 3089896475d5SAl Viro struct path path; 309016b1c1cdSMiklos Szeredi bool retried = false; 309116c2cd71SAl Viro int error; 3092fb1cc555SAl Viro 3093c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3094c3e380b0SAl Viro nd->flags |= op->intent; 3095c3e380b0SAl Viro 3096bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3097fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3098deb106c6SAl Viro if (unlikely(error)) 30992675a4ebSAl Viro return error; 3100e83db167SMiklos Szeredi goto finish_open; 31011f36f774SAl Viro } 3102a2c36b45SAl Viro 3103ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3104fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3105fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3106fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3107254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 310871574865SMiklos Szeredi if (likely(!error)) 310971574865SMiklos Szeredi goto finish_lookup; 311071574865SMiklos Szeredi 3111ce57dfc1SAl Viro if (error < 0) 3112deb106c6SAl Viro return error; 3113a1eb3315SMiklos Szeredi 311437d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 3115b6183df7SMiklos Szeredi } else { 3116fe2d35ffSAl Viro /* create side of things */ 3117a3fbbde7SAl Viro /* 3118b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3119b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3120b6183df7SMiklos Szeredi * about to look up 3121a3fbbde7SAl Viro */ 31229f1fafeeSAl Viro error = complete_walk(nd); 3123e8bb73dfSAl Viro if (error) 31242675a4ebSAl Viro return error; 3125fe2d35ffSAl Viro 312676ae2a5aSAl Viro audit_inode(nd->name, dir, LOOKUP_PARENT); 31271f36f774SAl Viro /* trailing slashes? */ 3128deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3129deb106c6SAl Viro return -EISDIR; 3130b6183df7SMiklos Szeredi } 31311f36f774SAl Viro 313216b1c1cdSMiklos Szeredi retry_lookup: 313364894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 313464894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 313564894cf8SAl Viro if (!error) 313664894cf8SAl Viro got_write = true; 313764894cf8SAl Viro /* 313864894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 313964894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 314064894cf8SAl Viro * dropping this one anyway. 314164894cf8SAl Viro */ 314264894cf8SAl Viro } 3143a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 3144896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 3145fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 3146fb1cc555SAl Viro 31472675a4ebSAl Viro if (error <= 0) { 31482675a4ebSAl Viro if (error) 3149d58ffd35SMiklos Szeredi goto out; 31506c0d46c4SAl Viro 315147237687SAl Viro if ((*opened & FILE_CREATED) || 3152496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 315377d660a8SMiklos Szeredi will_truncate = false; 3154d18e9008SMiklos Szeredi 315576ae2a5aSAl Viro audit_inode(nd->name, file->f_path.dentry, 0); 3156d18e9008SMiklos Szeredi goto opened; 3157d18e9008SMiklos Szeredi } 3158d18e9008SMiklos Szeredi 315947237687SAl Viro if (*opened & FILE_CREATED) { 31609b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3161ca344a89SAl Viro open_flag &= ~O_TRUNC; 316277d660a8SMiklos Szeredi will_truncate = false; 316362fb4a15SAl Viro acc_mode = 0; 3164896475d5SAl Viro path_to_nameidata(&path, nd); 3165e83db167SMiklos Szeredi goto finish_open_created; 3166fb1cc555SAl Viro } 3167fb1cc555SAl Viro 3168fb1cc555SAl Viro /* 31693134f37eSJeff Layton * create/update audit record if it already exists. 3170fb1cc555SAl Viro */ 3171896475d5SAl Viro if (d_is_positive(path.dentry)) 317276ae2a5aSAl Viro audit_inode(nd->name, path.dentry, 0); 3173fb1cc555SAl Viro 3174d18e9008SMiklos Szeredi /* 3175d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3176d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3177d18e9008SMiklos Szeredi * necessary...) 3178d18e9008SMiklos Szeredi */ 317964894cf8SAl Viro if (got_write) { 3180d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 318164894cf8SAl Viro got_write = false; 3182d18e9008SMiklos Szeredi } 3183d18e9008SMiklos Szeredi 3184deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3185deb106c6SAl Viro path_to_nameidata(&path, nd); 3186deb106c6SAl Viro return -EEXIST; 3187deb106c6SAl Viro } 3188fb1cc555SAl Viro 3189756daf26SNeilBrown error = follow_managed(&path, nd); 3190deb106c6SAl Viro if (unlikely(error < 0)) 3191deb106c6SAl Viro return error; 3192a3fbbde7SAl Viro 3193decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 319463afdfc7SDavid Howells inode = d_backing_inode(path.dentry); 3195254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3196deb106c6SAl Viro if (unlikely(d_is_negative(path.dentry))) { 3197896475d5SAl Viro path_to_nameidata(&path, nd); 3198deb106c6SAl Viro return -ENOENT; 319954c33e7fSMiklos Szeredi } 3200766c4cbfSAl Viro finish_lookup: 3201191d7f73SAl Viro if (nd->depth) 3202191d7f73SAl Viro put_link(nd); 3203181548c0SAl Viro error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW, 3204181548c0SAl Viro inode, seq); 3205deb106c6SAl Viro if (unlikely(error)) 3206d63ff28fSAl Viro return error; 3207fb1cc555SAl Viro 3208896475d5SAl Viro if (unlikely(d_is_symlink(path.dentry)) && !(open_flag & O_PATH)) { 3209896475d5SAl Viro path_to_nameidata(&path, nd); 3210deb106c6SAl Viro return -ELOOP; 3211a5cfe2d5SAl Viro } 3212a5cfe2d5SAl Viro 3213896475d5SAl Viro if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { 3214896475d5SAl Viro path_to_nameidata(&path, nd); 321516b1c1cdSMiklos Szeredi } else { 321616b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 3217896475d5SAl Viro save_parent.mnt = mntget(path.mnt); 3218896475d5SAl Viro nd->path.dentry = path.dentry; 321916b1c1cdSMiklos Szeredi 322016b1c1cdSMiklos Szeredi } 3221decf3400SMiklos Szeredi nd->inode = inode; 3222254cf582SAl Viro nd->seq = seq; 3223a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3224bc77daa7SAl Viro finish_open: 3225a3fbbde7SAl Viro error = complete_walk(nd); 322616b1c1cdSMiklos Szeredi if (error) { 322716b1c1cdSMiklos Szeredi path_put(&save_parent); 32282675a4ebSAl Viro return error; 322916b1c1cdSMiklos Szeredi } 323076ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 3231fb1cc555SAl Viro error = -EISDIR; 323244b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 32332675a4ebSAl Viro goto out; 3234af2f5542SMiklos Szeredi error = -ENOTDIR; 323544b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 32362675a4ebSAl Viro goto out; 32374bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 323877d660a8SMiklos Szeredi will_truncate = false; 32396c0d46c4SAl Viro 32400f9d1a10SAl Viro if (will_truncate) { 32410f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 32420f9d1a10SAl Viro if (error) 32432675a4ebSAl Viro goto out; 324464894cf8SAl Viro got_write = true; 32450f9d1a10SAl Viro } 3246e83db167SMiklos Szeredi finish_open_created: 324762fb4a15SAl Viro if (likely(!(open_flag & O_PATH))) { 3248bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3249ca344a89SAl Viro if (error) 32502675a4ebSAl Viro goto out; 325162fb4a15SAl Viro } 32524aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 32534aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 32544aa7c634SMiklos Szeredi if (!error) { 32554aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 32564aa7c634SMiklos Szeredi } else { 325730d90494SAl Viro if (error == -EOPENSTALE) 3258f60dc3dbSMiklos Szeredi goto stale_open; 3259015c3bbcSMiklos Szeredi goto out; 3260f60dc3dbSMiklos Szeredi } 3261a8277b9bSMiklos Szeredi opened: 32622675a4ebSAl Viro error = open_check_o_direct(file); 3263015c3bbcSMiklos Szeredi if (error) 3264015c3bbcSMiklos Szeredi goto exit_fput; 32653034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3266aa4caadbSMiklos Szeredi if (error) 3267aa4caadbSMiklos Szeredi goto exit_fput; 3268aa4caadbSMiklos Szeredi 32690f9d1a10SAl Viro if (will_truncate) { 32702675a4ebSAl Viro error = handle_truncate(file); 3271aa4caadbSMiklos Szeredi if (error) 3272aa4caadbSMiklos Szeredi goto exit_fput; 32730f9d1a10SAl Viro } 3274ca344a89SAl Viro out: 327564894cf8SAl Viro if (got_write) 32760f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 327716b1c1cdSMiklos Szeredi path_put(&save_parent); 32782675a4ebSAl Viro return error; 3279fb1cc555SAl Viro 3280015c3bbcSMiklos Szeredi exit_fput: 32812675a4ebSAl Viro fput(file); 32822675a4ebSAl Viro goto out; 3283015c3bbcSMiklos Szeredi 3284f60dc3dbSMiklos Szeredi stale_open: 3285f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3286f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3287f60dc3dbSMiklos Szeredi goto out; 3288f60dc3dbSMiklos Szeredi 3289f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3290f60dc3dbSMiklos Szeredi path_put(&nd->path); 3291f60dc3dbSMiklos Szeredi nd->path = save_parent; 3292f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3293f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3294f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 329564894cf8SAl Viro if (got_write) { 3296f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 329764894cf8SAl Viro got_write = false; 3298f60dc3dbSMiklos Szeredi } 3299f60dc3dbSMiklos Szeredi retried = true; 3300f60dc3dbSMiklos Szeredi goto retry_lookup; 3301fb1cc555SAl Viro } 3302fb1cc555SAl Viro 3303c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 330460545d0dSAl Viro const struct open_flags *op, 330560545d0dSAl Viro struct file *file, int *opened) 330660545d0dSAl Viro { 330760545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 3308625b6d10SAl Viro struct dentry *child; 330960545d0dSAl Viro struct inode *dir; 3310625b6d10SAl Viro struct path path; 3311c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 331260545d0dSAl Viro if (unlikely(error)) 331360545d0dSAl Viro return error; 3314625b6d10SAl Viro error = mnt_want_write(path.mnt); 331560545d0dSAl Viro if (unlikely(error)) 331660545d0dSAl Viro goto out; 3317625b6d10SAl Viro dir = path.dentry->d_inode; 331860545d0dSAl Viro /* we want directory to be writable */ 3319625b6d10SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 332060545d0dSAl Viro if (error) 332160545d0dSAl Viro goto out2; 332260545d0dSAl Viro if (!dir->i_op->tmpfile) { 332360545d0dSAl Viro error = -EOPNOTSUPP; 332460545d0dSAl Viro goto out2; 332560545d0dSAl Viro } 3326625b6d10SAl Viro child = d_alloc(path.dentry, &name); 332760545d0dSAl Viro if (unlikely(!child)) { 332860545d0dSAl Viro error = -ENOMEM; 332960545d0dSAl Viro goto out2; 333060545d0dSAl Viro } 3331625b6d10SAl Viro dput(path.dentry); 3332625b6d10SAl Viro path.dentry = child; 3333625b6d10SAl Viro error = dir->i_op->tmpfile(dir, child, op->mode); 333460545d0dSAl Viro if (error) 333560545d0dSAl Viro goto out2; 3336c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 333769a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 333862fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 333960545d0dSAl Viro if (error) 334060545d0dSAl Viro goto out2; 3341625b6d10SAl Viro file->f_path.mnt = path.mnt; 3342625b6d10SAl Viro error = finish_open(file, child, NULL, opened); 334360545d0dSAl Viro if (error) 334460545d0dSAl Viro goto out2; 334560545d0dSAl Viro error = open_check_o_direct(file); 3346f4e0c30cSAl Viro if (error) { 334760545d0dSAl Viro fput(file); 3348f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3349f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3350f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3351f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3352f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3353f4e0c30cSAl Viro } 335460545d0dSAl Viro out2: 3355625b6d10SAl Viro mnt_drop_write(path.mnt); 335660545d0dSAl Viro out: 3357625b6d10SAl Viro path_put(&path); 335860545d0dSAl Viro return error; 335960545d0dSAl Viro } 336060545d0dSAl Viro 3361c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3362c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 33631da177e4SLinus Torvalds { 3364368ee9baSAl Viro const char *s; 336530d90494SAl Viro struct file *file; 336647237687SAl Viro int opened = 0; 336713aab428SAl Viro int error; 336831e6b01fSNick Piggin 336930d90494SAl Viro file = get_empty_filp(); 33701afc99beSAl Viro if (IS_ERR(file)) 33711afc99beSAl Viro return file; 337231e6b01fSNick Piggin 337330d90494SAl Viro file->f_flags = op->open_flag; 337431e6b01fSNick Piggin 3375bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 3376c8a53ee5SAl Viro error = do_tmpfile(nd, flags, op, file, &opened); 3377f15133dfSAl Viro goto out2; 337860545d0dSAl Viro } 337960545d0dSAl Viro 3380c8a53ee5SAl Viro s = path_init(nd, flags); 3381368ee9baSAl Viro if (IS_ERR(s)) { 3382368ee9baSAl Viro put_filp(file); 3383368ee9baSAl Viro return ERR_CAST(s); 3384368ee9baSAl Viro } 33853bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 338676ae2a5aSAl Viro (error = do_last(nd, file, op, &opened)) > 0) { 338773d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 33883bdba28bSAl Viro s = trailing_symlink(nd); 33893bdba28bSAl Viro if (IS_ERR(s)) { 33903bdba28bSAl Viro error = PTR_ERR(s); 33912675a4ebSAl Viro break; 3392806b681cSAl Viro } 33933bdba28bSAl Viro } 3394deb106c6SAl Viro terminate_walk(nd); 3395f15133dfSAl Viro out2: 33962675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 33972675a4ebSAl Viro BUG_ON(!error); 339830d90494SAl Viro put_filp(file); 3399015c3bbcSMiklos Szeredi } 34002675a4ebSAl Viro if (unlikely(error)) { 34012675a4ebSAl Viro if (error == -EOPENSTALE) { 34022675a4ebSAl Viro if (flags & LOOKUP_RCU) 34032675a4ebSAl Viro error = -ECHILD; 34042675a4ebSAl Viro else 34052675a4ebSAl Viro error = -ESTALE; 34062675a4ebSAl Viro } 34072675a4ebSAl Viro file = ERR_PTR(error); 34082675a4ebSAl Viro } 34092675a4ebSAl Viro return file; 3410de459215SKirill Korotaev } 34111da177e4SLinus Torvalds 3412669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3413f9652e10SAl Viro const struct open_flags *op) 341413aab428SAl Viro { 34159883d185SAl Viro struct nameidata nd; 3416f9652e10SAl Viro int flags = op->lookup_flags; 341713aab428SAl Viro struct file *filp; 341813aab428SAl Viro 34199883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3420c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 342113aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3422c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 342313aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3424c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 34259883d185SAl Viro restore_nameidata(); 342613aab428SAl Viro return filp; 342713aab428SAl Viro } 342813aab428SAl Viro 342973d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3430f9652e10SAl Viro const char *name, const struct open_flags *op) 343173d049a4SAl Viro { 34329883d185SAl Viro struct nameidata nd; 343373d049a4SAl Viro struct file *file; 343451689104SPaul Moore struct filename *filename; 3435f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 343673d049a4SAl Viro 343773d049a4SAl Viro nd.root.mnt = mnt; 343873d049a4SAl Viro nd.root.dentry = dentry; 343973d049a4SAl Viro 3440b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 344173d049a4SAl Viro return ERR_PTR(-ELOOP); 344273d049a4SAl Viro 344351689104SPaul Moore filename = getname_kernel(name); 3444a1c83681SViresh Kumar if (IS_ERR(filename)) 344551689104SPaul Moore return ERR_CAST(filename); 344651689104SPaul Moore 34479883d185SAl Viro set_nameidata(&nd, -1, filename); 3448c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 344973d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3450c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 345173d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3452c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 34539883d185SAl Viro restore_nameidata(); 345451689104SPaul Moore putname(filename); 345573d049a4SAl Viro return file; 345673d049a4SAl Viro } 345773d049a4SAl Viro 3458fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 34591ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 34601da177e4SLinus Torvalds { 3461c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3462391172c4SAl Viro struct qstr last; 3463391172c4SAl Viro int type; 3464c30dabfeSJan Kara int err2; 34651ac12b4bSJeff Layton int error; 34661ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 34671ac12b4bSJeff Layton 34681ac12b4bSJeff Layton /* 34691ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 34701ac12b4bSJeff Layton * other flags passed in are ignored! 34711ac12b4bSJeff Layton */ 34721ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 34731ac12b4bSJeff Layton 34745c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 34755c31b6ceSAl Viro if (IS_ERR(name)) 34765c31b6ceSAl Viro return ERR_CAST(name); 34771da177e4SLinus Torvalds 3478c663e5d8SChristoph Hellwig /* 3479c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3480c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3481c663e5d8SChristoph Hellwig */ 34825c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3483ed75e95dSAl Viro goto out; 3484c663e5d8SChristoph Hellwig 3485c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3486391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3487c663e5d8SChristoph Hellwig /* 3488c663e5d8SChristoph Hellwig * Do the final lookup. 3489c663e5d8SChristoph Hellwig */ 3490391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 3491391172c4SAl Viro mutex_lock_nested(&path->dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3492391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 34931da177e4SLinus Torvalds if (IS_ERR(dentry)) 3494a8104a9fSAl Viro goto unlock; 3495c663e5d8SChristoph Hellwig 3496a8104a9fSAl Viro error = -EEXIST; 3497b18825a7SDavid Howells if (d_is_positive(dentry)) 3498a8104a9fSAl Viro goto fail; 3499b18825a7SDavid Howells 3500c663e5d8SChristoph Hellwig /* 3501c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3502c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3503c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3504c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3505c663e5d8SChristoph Hellwig */ 3506391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3507a8104a9fSAl Viro error = -ENOENT; 3508ed75e95dSAl Viro goto fail; 3509e9baf6e5SAl Viro } 3510c30dabfeSJan Kara if (unlikely(err2)) { 3511c30dabfeSJan Kara error = err2; 3512a8104a9fSAl Viro goto fail; 3513c30dabfeSJan Kara } 3514181c37b6SAl Viro putname(name); 3515e9baf6e5SAl Viro return dentry; 35161da177e4SLinus Torvalds fail: 3517a8104a9fSAl Viro dput(dentry); 3518a8104a9fSAl Viro dentry = ERR_PTR(error); 3519a8104a9fSAl Viro unlock: 3520391172c4SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3521c30dabfeSJan Kara if (!err2) 3522391172c4SAl Viro mnt_drop_write(path->mnt); 3523ed75e95dSAl Viro out: 3524391172c4SAl Viro path_put(path); 3525181c37b6SAl Viro putname(name); 3526ed75e95dSAl Viro return dentry; 3527dae6ad8fSAl Viro } 3528fa14a0b8SAl Viro 3529fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3530fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3531fa14a0b8SAl Viro { 3532181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3533181c37b6SAl Viro path, lookup_flags); 3534fa14a0b8SAl Viro } 3535dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3536dae6ad8fSAl Viro 3537921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3538921a1650SAl Viro { 3539921a1650SAl Viro dput(dentry); 3540921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3541a8104a9fSAl Viro mnt_drop_write(path->mnt); 3542921a1650SAl Viro path_put(path); 3543921a1650SAl Viro } 3544921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3545921a1650SAl Viro 3546520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 35471ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3548dae6ad8fSAl Viro { 3549181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3550dae6ad8fSAl Viro } 3551dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3552dae6ad8fSAl Viro 35531a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 35541da177e4SLinus Torvalds { 3555a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35561da177e4SLinus Torvalds 35571da177e4SLinus Torvalds if (error) 35581da177e4SLinus Torvalds return error; 35591da177e4SLinus Torvalds 3560975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 35611da177e4SLinus Torvalds return -EPERM; 35621da177e4SLinus Torvalds 3563acfa4380SAl Viro if (!dir->i_op->mknod) 35641da177e4SLinus Torvalds return -EPERM; 35651da177e4SLinus Torvalds 356608ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 356708ce5f16SSerge E. Hallyn if (error) 356808ce5f16SSerge E. Hallyn return error; 356908ce5f16SSerge E. Hallyn 35701da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 35711da177e4SLinus Torvalds if (error) 35721da177e4SLinus Torvalds return error; 35731da177e4SLinus Torvalds 35741da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3575a74574aaSStephen Smalley if (!error) 3576f38aa942SAmy Griffis fsnotify_create(dir, dentry); 35771da177e4SLinus Torvalds return error; 35781da177e4SLinus Torvalds } 35794d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 35801da177e4SLinus Torvalds 3581f69aac00SAl Viro static int may_mknod(umode_t mode) 3582463c3197SDave Hansen { 3583463c3197SDave Hansen switch (mode & S_IFMT) { 3584463c3197SDave Hansen case S_IFREG: 3585463c3197SDave Hansen case S_IFCHR: 3586463c3197SDave Hansen case S_IFBLK: 3587463c3197SDave Hansen case S_IFIFO: 3588463c3197SDave Hansen case S_IFSOCK: 3589463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3590463c3197SDave Hansen return 0; 3591463c3197SDave Hansen case S_IFDIR: 3592463c3197SDave Hansen return -EPERM; 3593463c3197SDave Hansen default: 3594463c3197SDave Hansen return -EINVAL; 3595463c3197SDave Hansen } 3596463c3197SDave Hansen } 3597463c3197SDave Hansen 35988208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 35992e4d0924SHeiko Carstens unsigned, dev) 36001da177e4SLinus Torvalds { 36011da177e4SLinus Torvalds struct dentry *dentry; 3602dae6ad8fSAl Viro struct path path; 3603dae6ad8fSAl Viro int error; 3604972567f1SJeff Layton unsigned int lookup_flags = 0; 36051da177e4SLinus Torvalds 36068e4bfca1SAl Viro error = may_mknod(mode); 36078e4bfca1SAl Viro if (error) 36088e4bfca1SAl Viro return error; 3609972567f1SJeff Layton retry: 3610972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3611dae6ad8fSAl Viro if (IS_ERR(dentry)) 3612dae6ad8fSAl Viro return PTR_ERR(dentry); 36132ad94ae6SAl Viro 3614dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3615ce3b0f8dSAl Viro mode &= ~current_umask(); 3616dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3617be6d3e56SKentaro Takeda if (error) 3618a8104a9fSAl Viro goto out; 36191da177e4SLinus Torvalds switch (mode & S_IFMT) { 36201da177e4SLinus Torvalds case 0: case S_IFREG: 3621312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 36221da177e4SLinus Torvalds break; 36231da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3624dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 36251da177e4SLinus Torvalds new_decode_dev(dev)); 36261da177e4SLinus Torvalds break; 36271da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3628dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 36291da177e4SLinus Torvalds break; 36301da177e4SLinus Torvalds } 3631a8104a9fSAl Viro out: 3632921a1650SAl Viro done_path_create(&path, dentry); 3633972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3634972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3635972567f1SJeff Layton goto retry; 3636972567f1SJeff Layton } 36371da177e4SLinus Torvalds return error; 36381da177e4SLinus Torvalds } 36391da177e4SLinus Torvalds 36408208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 36415590ff0dSUlrich Drepper { 36425590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 36435590ff0dSUlrich Drepper } 36445590ff0dSUlrich Drepper 364518bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 36461da177e4SLinus Torvalds { 3647a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36488de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 36491da177e4SLinus Torvalds 36501da177e4SLinus Torvalds if (error) 36511da177e4SLinus Torvalds return error; 36521da177e4SLinus Torvalds 3653acfa4380SAl Viro if (!dir->i_op->mkdir) 36541da177e4SLinus Torvalds return -EPERM; 36551da177e4SLinus Torvalds 36561da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 36571da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 36581da177e4SLinus Torvalds if (error) 36591da177e4SLinus Torvalds return error; 36601da177e4SLinus Torvalds 36618de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 36628de52778SAl Viro return -EMLINK; 36638de52778SAl Viro 36641da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3665a74574aaSStephen Smalley if (!error) 3666f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 36671da177e4SLinus Torvalds return error; 36681da177e4SLinus Torvalds } 36694d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 36701da177e4SLinus Torvalds 3671a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 36721da177e4SLinus Torvalds { 36736902d925SDave Hansen struct dentry *dentry; 3674dae6ad8fSAl Viro struct path path; 3675dae6ad8fSAl Viro int error; 3676b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 36771da177e4SLinus Torvalds 3678b76d8b82SJeff Layton retry: 3679b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 36806902d925SDave Hansen if (IS_ERR(dentry)) 3681dae6ad8fSAl Viro return PTR_ERR(dentry); 36826902d925SDave Hansen 3683dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3684ce3b0f8dSAl Viro mode &= ~current_umask(); 3685dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3686a8104a9fSAl Viro if (!error) 3687dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3688921a1650SAl Viro done_path_create(&path, dentry); 3689b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3690b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3691b76d8b82SJeff Layton goto retry; 3692b76d8b82SJeff Layton } 36931da177e4SLinus Torvalds return error; 36941da177e4SLinus Torvalds } 36951da177e4SLinus Torvalds 3696a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 36975590ff0dSUlrich Drepper { 36985590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 36995590ff0dSUlrich Drepper } 37005590ff0dSUlrich Drepper 37011da177e4SLinus Torvalds /* 3702a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3703c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3704a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3705a71905f0SSage Weil * then we drop the dentry now. 37061da177e4SLinus Torvalds * 37071da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 37081da177e4SLinus Torvalds * do a 37091da177e4SLinus Torvalds * 37101da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 37111da177e4SLinus Torvalds * return -EBUSY; 37121da177e4SLinus Torvalds * 37131da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 37141da177e4SLinus Torvalds * that is still in use by something else.. 37151da177e4SLinus Torvalds */ 37161da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 37171da177e4SLinus Torvalds { 37181da177e4SLinus Torvalds shrink_dcache_parent(dentry); 37191da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 372098474236SWaiman Long if (dentry->d_lockref.count == 1) 37211da177e4SLinus Torvalds __d_drop(dentry); 37221da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 37231da177e4SLinus Torvalds } 37244d359507SAl Viro EXPORT_SYMBOL(dentry_unhash); 37251da177e4SLinus Torvalds 37261da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 37271da177e4SLinus Torvalds { 37281da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 37291da177e4SLinus Torvalds 37301da177e4SLinus Torvalds if (error) 37311da177e4SLinus Torvalds return error; 37321da177e4SLinus Torvalds 3733acfa4380SAl Viro if (!dir->i_op->rmdir) 37341da177e4SLinus Torvalds return -EPERM; 37351da177e4SLinus Torvalds 37361d2ef590SAl Viro dget(dentry); 37371b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3738912dbc15SSage Weil 37391da177e4SLinus Torvalds error = -EBUSY; 37407af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3741912dbc15SSage Weil goto out; 3742912dbc15SSage Weil 37431da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3744912dbc15SSage Weil if (error) 3745912dbc15SSage Weil goto out; 3746912dbc15SSage Weil 37473cebde24SSage Weil shrink_dcache_parent(dentry); 37481da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3749912dbc15SSage Weil if (error) 3750912dbc15SSage Weil goto out; 3751912dbc15SSage Weil 37521da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3753d83c49f3SAl Viro dont_mount(dentry); 37548ed936b5SEric W. Biederman detach_mounts(dentry); 37551da177e4SLinus Torvalds 3756912dbc15SSage Weil out: 3757912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 37581d2ef590SAl Viro dput(dentry); 3759912dbc15SSage Weil if (!error) 3760912dbc15SSage Weil d_delete(dentry); 37611da177e4SLinus Torvalds return error; 37621da177e4SLinus Torvalds } 37634d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 37641da177e4SLinus Torvalds 37655590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 37661da177e4SLinus Torvalds { 37671da177e4SLinus Torvalds int error = 0; 376891a27b2aSJeff Layton struct filename *name; 37691da177e4SLinus Torvalds struct dentry *dentry; 3770f5beed75SAl Viro struct path path; 3771f5beed75SAl Viro struct qstr last; 3772f5beed75SAl Viro int type; 3773c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3774c6ee9206SJeff Layton retry: 3775f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3776f5beed75SAl Viro &path, &last, &type, lookup_flags); 377791a27b2aSJeff Layton if (IS_ERR(name)) 377891a27b2aSJeff Layton return PTR_ERR(name); 37791da177e4SLinus Torvalds 3780f5beed75SAl Viro switch (type) { 37811da177e4SLinus Torvalds case LAST_DOTDOT: 37821da177e4SLinus Torvalds error = -ENOTEMPTY; 37831da177e4SLinus Torvalds goto exit1; 37841da177e4SLinus Torvalds case LAST_DOT: 37851da177e4SLinus Torvalds error = -EINVAL; 37861da177e4SLinus Torvalds goto exit1; 37871da177e4SLinus Torvalds case LAST_ROOT: 37881da177e4SLinus Torvalds error = -EBUSY; 37891da177e4SLinus Torvalds goto exit1; 37901da177e4SLinus Torvalds } 37910612d9fbSOGAWA Hirofumi 3792f5beed75SAl Viro error = mnt_want_write(path.mnt); 3793c30dabfeSJan Kara if (error) 3794c30dabfeSJan Kara goto exit1; 37950612d9fbSOGAWA Hirofumi 3796f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3797f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 37981da177e4SLinus Torvalds error = PTR_ERR(dentry); 37996902d925SDave Hansen if (IS_ERR(dentry)) 38006902d925SDave Hansen goto exit2; 3801e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3802e6bc45d6STheodore Ts'o error = -ENOENT; 3803e6bc45d6STheodore Ts'o goto exit3; 3804e6bc45d6STheodore Ts'o } 3805f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3806be6d3e56SKentaro Takeda if (error) 3807c30dabfeSJan Kara goto exit3; 3808f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 38090622753bSDave Hansen exit3: 38101da177e4SLinus Torvalds dput(dentry); 38116902d925SDave Hansen exit2: 3812f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 3813f5beed75SAl Viro mnt_drop_write(path.mnt); 38141da177e4SLinus Torvalds exit1: 3815f5beed75SAl Viro path_put(&path); 38161da177e4SLinus Torvalds putname(name); 3817c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3818c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3819c6ee9206SJeff Layton goto retry; 3820c6ee9206SJeff Layton } 38211da177e4SLinus Torvalds return error; 38221da177e4SLinus Torvalds } 38231da177e4SLinus Torvalds 38243cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 38255590ff0dSUlrich Drepper { 38265590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 38275590ff0dSUlrich Drepper } 38285590ff0dSUlrich Drepper 3829b21996e3SJ. Bruce Fields /** 3830b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3831b21996e3SJ. Bruce Fields * @dir: parent directory 3832b21996e3SJ. Bruce Fields * @dentry: victim 3833b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3834b21996e3SJ. Bruce Fields * 3835b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3836b21996e3SJ. Bruce Fields * 3837b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3838b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3839b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3840b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3841b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3842b21996e3SJ. Bruce Fields * 3843b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3844b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3845b21996e3SJ. Bruce Fields * to be NFS exported. 3846b21996e3SJ. Bruce Fields */ 3847b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 38481da177e4SLinus Torvalds { 38499accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 38501da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 38511da177e4SLinus Torvalds 38521da177e4SLinus Torvalds if (error) 38531da177e4SLinus Torvalds return error; 38541da177e4SLinus Torvalds 3855acfa4380SAl Viro if (!dir->i_op->unlink) 38561da177e4SLinus Torvalds return -EPERM; 38571da177e4SLinus Torvalds 38589accbb97SJ. Bruce Fields mutex_lock(&target->i_mutex); 38598ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 38601da177e4SLinus Torvalds error = -EBUSY; 38611da177e4SLinus Torvalds else { 38621da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3863bec1052eSAl Viro if (!error) { 38645a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 38655a14696cSJ. Bruce Fields if (error) 3866b21996e3SJ. Bruce Fields goto out; 38671da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 38688ed936b5SEric W. Biederman if (!error) { 3869d83c49f3SAl Viro dont_mount(dentry); 38708ed936b5SEric W. Biederman detach_mounts(dentry); 38718ed936b5SEric W. Biederman } 3872bec1052eSAl Viro } 38731da177e4SLinus Torvalds } 3874b21996e3SJ. Bruce Fields out: 38759accbb97SJ. Bruce Fields mutex_unlock(&target->i_mutex); 38761da177e4SLinus Torvalds 38771da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 38781da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 38799accbb97SJ. Bruce Fields fsnotify_link_count(target); 38801da177e4SLinus Torvalds d_delete(dentry); 38811da177e4SLinus Torvalds } 38820eeca283SRobert Love 38831da177e4SLinus Torvalds return error; 38841da177e4SLinus Torvalds } 38854d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 38861da177e4SLinus Torvalds 38871da177e4SLinus Torvalds /* 38881da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 38891b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 38901da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 38911da177e4SLinus Torvalds * while waiting on the I/O. 38921da177e4SLinus Torvalds */ 38935590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 38941da177e4SLinus Torvalds { 38952ad94ae6SAl Viro int error; 389691a27b2aSJeff Layton struct filename *name; 38971da177e4SLinus Torvalds struct dentry *dentry; 3898f5beed75SAl Viro struct path path; 3899f5beed75SAl Viro struct qstr last; 3900f5beed75SAl Viro int type; 39011da177e4SLinus Torvalds struct inode *inode = NULL; 3902b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 39035d18f813SJeff Layton unsigned int lookup_flags = 0; 39045d18f813SJeff Layton retry: 3905f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3906f5beed75SAl Viro &path, &last, &type, lookup_flags); 390791a27b2aSJeff Layton if (IS_ERR(name)) 390891a27b2aSJeff Layton return PTR_ERR(name); 39092ad94ae6SAl Viro 39101da177e4SLinus Torvalds error = -EISDIR; 3911f5beed75SAl Viro if (type != LAST_NORM) 39121da177e4SLinus Torvalds goto exit1; 39130612d9fbSOGAWA Hirofumi 3914f5beed75SAl Viro error = mnt_want_write(path.mnt); 3915c30dabfeSJan Kara if (error) 3916c30dabfeSJan Kara goto exit1; 3917b21996e3SJ. Bruce Fields retry_deleg: 3918f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3919f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 39201da177e4SLinus Torvalds error = PTR_ERR(dentry); 39211da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 39221da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3923f5beed75SAl Viro if (last.name[last.len]) 392450338b88STörök Edwin goto slashes; 39251da177e4SLinus Torvalds inode = dentry->d_inode; 3926b18825a7SDavid Howells if (d_is_negative(dentry)) 3927e6bc45d6STheodore Ts'o goto slashes; 39287de9c6eeSAl Viro ihold(inode); 3929f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3930be6d3e56SKentaro Takeda if (error) 3931c30dabfeSJan Kara goto exit2; 3932f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 39331da177e4SLinus Torvalds exit2: 39341da177e4SLinus Torvalds dput(dentry); 39351da177e4SLinus Torvalds } 3936f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 39371da177e4SLinus Torvalds if (inode) 39381da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3939b21996e3SJ. Bruce Fields inode = NULL; 3940b21996e3SJ. Bruce Fields if (delegated_inode) { 39415a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3942b21996e3SJ. Bruce Fields if (!error) 3943b21996e3SJ. Bruce Fields goto retry_deleg; 3944b21996e3SJ. Bruce Fields } 3945f5beed75SAl Viro mnt_drop_write(path.mnt); 39461da177e4SLinus Torvalds exit1: 3947f5beed75SAl Viro path_put(&path); 39481da177e4SLinus Torvalds putname(name); 39495d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 39505d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 39515d18f813SJeff Layton inode = NULL; 39525d18f813SJeff Layton goto retry; 39535d18f813SJeff Layton } 39541da177e4SLinus Torvalds return error; 39551da177e4SLinus Torvalds 39561da177e4SLinus Torvalds slashes: 3957b18825a7SDavid Howells if (d_is_negative(dentry)) 3958b18825a7SDavid Howells error = -ENOENT; 395944b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3960b18825a7SDavid Howells error = -EISDIR; 3961b18825a7SDavid Howells else 3962b18825a7SDavid Howells error = -ENOTDIR; 39631da177e4SLinus Torvalds goto exit2; 39641da177e4SLinus Torvalds } 39651da177e4SLinus Torvalds 39662e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 39675590ff0dSUlrich Drepper { 39685590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 39695590ff0dSUlrich Drepper return -EINVAL; 39705590ff0dSUlrich Drepper 39715590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 39725590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 39735590ff0dSUlrich Drepper 39745590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 39755590ff0dSUlrich Drepper } 39765590ff0dSUlrich Drepper 39773480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 39785590ff0dSUlrich Drepper { 39795590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 39805590ff0dSUlrich Drepper } 39815590ff0dSUlrich Drepper 3982db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 39831da177e4SLinus Torvalds { 3984a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 39851da177e4SLinus Torvalds 39861da177e4SLinus Torvalds if (error) 39871da177e4SLinus Torvalds return error; 39881da177e4SLinus Torvalds 3989acfa4380SAl Viro if (!dir->i_op->symlink) 39901da177e4SLinus Torvalds return -EPERM; 39911da177e4SLinus Torvalds 39921da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 39931da177e4SLinus Torvalds if (error) 39941da177e4SLinus Torvalds return error; 39951da177e4SLinus Torvalds 39961da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3997a74574aaSStephen Smalley if (!error) 3998f38aa942SAmy Griffis fsnotify_create(dir, dentry); 39991da177e4SLinus Torvalds return error; 40001da177e4SLinus Torvalds } 40014d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 40021da177e4SLinus Torvalds 40032e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 40042e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 40051da177e4SLinus Torvalds { 40062ad94ae6SAl Viro int error; 400791a27b2aSJeff Layton struct filename *from; 40086902d925SDave Hansen struct dentry *dentry; 4009dae6ad8fSAl Viro struct path path; 4010f46d3567SJeff Layton unsigned int lookup_flags = 0; 40111da177e4SLinus Torvalds 40121da177e4SLinus Torvalds from = getname(oldname); 40131da177e4SLinus Torvalds if (IS_ERR(from)) 40141da177e4SLinus Torvalds return PTR_ERR(from); 4015f46d3567SJeff Layton retry: 4016f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 40171da177e4SLinus Torvalds error = PTR_ERR(dentry); 40186902d925SDave Hansen if (IS_ERR(dentry)) 4019dae6ad8fSAl Viro goto out_putname; 40206902d925SDave Hansen 402191a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4022a8104a9fSAl Viro if (!error) 402391a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4024921a1650SAl Viro done_path_create(&path, dentry); 4025f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4026f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4027f46d3567SJeff Layton goto retry; 4028f46d3567SJeff Layton } 40296902d925SDave Hansen out_putname: 40301da177e4SLinus Torvalds putname(from); 40311da177e4SLinus Torvalds return error; 40321da177e4SLinus Torvalds } 40331da177e4SLinus Torvalds 40343480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 40355590ff0dSUlrich Drepper { 40365590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 40375590ff0dSUlrich Drepper } 40385590ff0dSUlrich Drepper 4039146a8595SJ. Bruce Fields /** 4040146a8595SJ. Bruce Fields * vfs_link - create a new link 4041146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4042146a8595SJ. Bruce Fields * @dir: new parent 4043146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4044146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4045146a8595SJ. Bruce Fields * 4046146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4047146a8595SJ. Bruce Fields * 4048146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4049146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4050146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4051146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4052146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4053146a8595SJ. Bruce Fields * 4054146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4055146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4056146a8595SJ. Bruce Fields * to be NFS exported. 4057146a8595SJ. Bruce Fields */ 4058146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 40591da177e4SLinus Torvalds { 40601da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 40618de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 40621da177e4SLinus Torvalds int error; 40631da177e4SLinus Torvalds 40641da177e4SLinus Torvalds if (!inode) 40651da177e4SLinus Torvalds return -ENOENT; 40661da177e4SLinus Torvalds 4067a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 40681da177e4SLinus Torvalds if (error) 40691da177e4SLinus Torvalds return error; 40701da177e4SLinus Torvalds 40711da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 40721da177e4SLinus Torvalds return -EXDEV; 40731da177e4SLinus Torvalds 40741da177e4SLinus Torvalds /* 40751da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 40761da177e4SLinus Torvalds */ 40771da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 40781da177e4SLinus Torvalds return -EPERM; 4079acfa4380SAl Viro if (!dir->i_op->link) 40801da177e4SLinus Torvalds return -EPERM; 40817e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 40821da177e4SLinus Torvalds return -EPERM; 40831da177e4SLinus Torvalds 40841da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 40851da177e4SLinus Torvalds if (error) 40861da177e4SLinus Torvalds return error; 40871da177e4SLinus Torvalds 40887e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 4089aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4090f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4091aae8a97dSAneesh Kumar K.V error = -ENOENT; 40928de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 40938de52778SAl Viro error = -EMLINK; 4094146a8595SJ. Bruce Fields else { 4095146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4096146a8595SJ. Bruce Fields if (!error) 40971da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4098146a8595SJ. Bruce Fields } 4099f4e0c30cSAl Viro 4100f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4101f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4102f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4103f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4104f4e0c30cSAl Viro } 41057e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 4106e31e14ecSStephen Smalley if (!error) 41077e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 41081da177e4SLinus Torvalds return error; 41091da177e4SLinus Torvalds } 41104d359507SAl Viro EXPORT_SYMBOL(vfs_link); 41111da177e4SLinus Torvalds 41121da177e4SLinus Torvalds /* 41131da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 41141da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 41151da177e4SLinus Torvalds * newname. --KAB 41161da177e4SLinus Torvalds * 41171da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 41181da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 41191da177e4SLinus Torvalds * and other special files. --ADM 41201da177e4SLinus Torvalds */ 41212e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 41222e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 41231da177e4SLinus Torvalds { 41241da177e4SLinus Torvalds struct dentry *new_dentry; 4125dae6ad8fSAl Viro struct path old_path, new_path; 4126146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 412711a7b371SAneesh Kumar K.V int how = 0; 41281da177e4SLinus Torvalds int error; 41291da177e4SLinus Torvalds 413011a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4131c04030e1SUlrich Drepper return -EINVAL; 413211a7b371SAneesh Kumar K.V /* 4133f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4134f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4135f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 413611a7b371SAneesh Kumar K.V */ 4137f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4138f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4139f0cc6ffbSLinus Torvalds return -ENOENT; 414011a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4141f0cc6ffbSLinus Torvalds } 4142c04030e1SUlrich Drepper 414311a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 414411a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4145442e31caSJeff Layton retry: 414611a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 41471da177e4SLinus Torvalds if (error) 41482ad94ae6SAl Viro return error; 41492ad94ae6SAl Viro 4150442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4151442e31caSJeff Layton (how & LOOKUP_REVAL)); 41521da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 41536902d925SDave Hansen if (IS_ERR(new_dentry)) 4154dae6ad8fSAl Viro goto out; 4155dae6ad8fSAl Viro 4156dae6ad8fSAl Viro error = -EXDEV; 4157dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4158dae6ad8fSAl Viro goto out_dput; 4159800179c9SKees Cook error = may_linkat(&old_path); 4160800179c9SKees Cook if (unlikely(error)) 4161800179c9SKees Cook goto out_dput; 4162dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4163be6d3e56SKentaro Takeda if (error) 4164a8104a9fSAl Viro goto out_dput; 4165146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 416675c3f29dSDave Hansen out_dput: 4167921a1650SAl Viro done_path_create(&new_path, new_dentry); 4168146a8595SJ. Bruce Fields if (delegated_inode) { 4169146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4170d22e6338SOleg Drokin if (!error) { 4171d22e6338SOleg Drokin path_put(&old_path); 4172146a8595SJ. Bruce Fields goto retry; 4173146a8595SJ. Bruce Fields } 4174d22e6338SOleg Drokin } 4175442e31caSJeff Layton if (retry_estale(error, how)) { 4176d22e6338SOleg Drokin path_put(&old_path); 4177442e31caSJeff Layton how |= LOOKUP_REVAL; 4178442e31caSJeff Layton goto retry; 4179442e31caSJeff Layton } 41801da177e4SLinus Torvalds out: 41812d8f3038SAl Viro path_put(&old_path); 41821da177e4SLinus Torvalds 41831da177e4SLinus Torvalds return error; 41841da177e4SLinus Torvalds } 41851da177e4SLinus Torvalds 41863480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 41875590ff0dSUlrich Drepper { 4188c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 41895590ff0dSUlrich Drepper } 41905590ff0dSUlrich Drepper 4191bc27027aSMiklos Szeredi /** 4192bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4193bc27027aSMiklos Szeredi * @old_dir: parent of source 4194bc27027aSMiklos Szeredi * @old_dentry: source 4195bc27027aSMiklos Szeredi * @new_dir: parent of destination 4196bc27027aSMiklos Szeredi * @new_dentry: destination 4197bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4198520c8b16SMiklos Szeredi * @flags: rename flags 4199bc27027aSMiklos Szeredi * 4200bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4201bc27027aSMiklos Szeredi * 4202bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4203bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4204bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4205bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4206bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4207bc27027aSMiklos Szeredi * so. 4208bc27027aSMiklos Szeredi * 4209bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4210bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4211bc27027aSMiklos Szeredi * to be NFS exported. 4212bc27027aSMiklos Szeredi * 42131da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 42141da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 42151da177e4SLinus Torvalds * Problems: 4216d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 42171da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 42181da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4219a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 42201da177e4SLinus Torvalds * story. 42216cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 42226cedba89SJ. Bruce Fields * and source (if it is not a directory). 42231b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 42241da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 42251da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4226a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 42271da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 42281da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 42291da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4230a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 42311da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 42321da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 42331da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4234e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 42351b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 42361da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4237c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 42381da177e4SLinus Torvalds * locking]. 42391da177e4SLinus Torvalds */ 42401da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 42418e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4242520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 42431da177e4SLinus Torvalds { 42441da177e4SLinus Torvalds int error; 4245bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 424659b0df21SEric Paris const unsigned char *old_name; 4247bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4248bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4249da1ce067SMiklos Szeredi bool new_is_dir = false; 4250da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 42511da177e4SLinus Torvalds 4252bc27027aSMiklos Szeredi if (source == target) 42531da177e4SLinus Torvalds return 0; 42541da177e4SLinus Torvalds 42551da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 42561da177e4SLinus Torvalds if (error) 42571da177e4SLinus Torvalds return error; 42581da177e4SLinus Torvalds 4259da1ce067SMiklos Szeredi if (!target) { 4260a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4261da1ce067SMiklos Szeredi } else { 4262da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4263da1ce067SMiklos Szeredi 4264da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 42651da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4266da1ce067SMiklos Szeredi else 4267da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4268da1ce067SMiklos Szeredi } 42691da177e4SLinus Torvalds if (error) 42701da177e4SLinus Torvalds return error; 42711da177e4SLinus Torvalds 42727177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 42731da177e4SLinus Torvalds return -EPERM; 42741da177e4SLinus Torvalds 4275520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4276520c8b16SMiklos Szeredi return -EINVAL; 4277520c8b16SMiklos Szeredi 4278bc27027aSMiklos Szeredi /* 4279bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4280bc27027aSMiklos Szeredi * we'll need to flip '..'. 4281bc27027aSMiklos Szeredi */ 4282da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4283da1ce067SMiklos Szeredi if (is_dir) { 4284bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4285bc27027aSMiklos Szeredi if (error) 4286bc27027aSMiklos Szeredi return error; 4287bc27027aSMiklos Szeredi } 4288da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4289da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4290da1ce067SMiklos Szeredi if (error) 4291da1ce067SMiklos Szeredi return error; 4292da1ce067SMiklos Szeredi } 4293da1ce067SMiklos Szeredi } 42940eeca283SRobert Love 42950b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 42960b3974ebSMiklos Szeredi flags); 4297bc27027aSMiklos Szeredi if (error) 4298bc27027aSMiklos Szeredi return error; 4299bc27027aSMiklos Szeredi 4300bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4301bc27027aSMiklos Szeredi dget(new_dentry); 4302da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4303bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4304bc27027aSMiklos Szeredi else if (target) 4305bc27027aSMiklos Szeredi mutex_lock(&target->i_mutex); 4306bc27027aSMiklos Szeredi 4307bc27027aSMiklos Szeredi error = -EBUSY; 43087af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4309bc27027aSMiklos Szeredi goto out; 4310bc27027aSMiklos Szeredi 4311da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4312bc27027aSMiklos Szeredi error = -EMLINK; 4313da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4314bc27027aSMiklos Szeredi goto out; 4315da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4316da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4317da1ce067SMiklos Szeredi goto out; 4318da1ce067SMiklos Szeredi } 4319da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4320bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4321da1ce067SMiklos Szeredi if (!is_dir) { 4322bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4323bc27027aSMiklos Szeredi if (error) 4324bc27027aSMiklos Szeredi goto out; 4325da1ce067SMiklos Szeredi } 4326da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4327bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4328bc27027aSMiklos Szeredi if (error) 4329bc27027aSMiklos Szeredi goto out; 4330bc27027aSMiklos Szeredi } 43317177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4332520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4333520c8b16SMiklos Szeredi new_dir, new_dentry); 4334520c8b16SMiklos Szeredi } else { 43357177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4336520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4337520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4338520c8b16SMiklos Szeredi } 4339bc27027aSMiklos Szeredi if (error) 4340bc27027aSMiklos Szeredi goto out; 4341bc27027aSMiklos Szeredi 4342da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 43431da177e4SLinus Torvalds if (is_dir) 4344bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4345bc27027aSMiklos Szeredi dont_mount(new_dentry); 43468ed936b5SEric W. Biederman detach_mounts(new_dentry); 4347bc27027aSMiklos Szeredi } 4348da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4349da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4350bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4351da1ce067SMiklos Szeredi else 4352da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4353da1ce067SMiklos Szeredi } 4354bc27027aSMiklos Szeredi out: 4355da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4356bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4357bc27027aSMiklos Szeredi else if (target) 4358bc27027aSMiklos Szeredi mutex_unlock(&target->i_mutex); 4359bc27027aSMiklos Szeredi dput(new_dentry); 4360da1ce067SMiklos Szeredi if (!error) { 4361123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4362da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4363da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4364da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4365da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4366da1ce067SMiklos Szeredi } 4367da1ce067SMiklos Szeredi } 43680eeca283SRobert Love fsnotify_oldname_free(old_name); 43690eeca283SRobert Love 43701da177e4SLinus Torvalds return error; 43711da177e4SLinus Torvalds } 43724d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 43731da177e4SLinus Torvalds 4374520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4375520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 43761da177e4SLinus Torvalds { 43771da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 43781da177e4SLinus Torvalds struct dentry *trap; 4379f5beed75SAl Viro struct path old_path, new_path; 4380f5beed75SAl Viro struct qstr old_last, new_last; 4381f5beed75SAl Viro int old_type, new_type; 43828e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 438391a27b2aSJeff Layton struct filename *from; 438491a27b2aSJeff Layton struct filename *to; 4385f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4386c6a94284SJeff Layton bool should_retry = false; 43872ad94ae6SAl Viro int error; 4388520c8b16SMiklos Szeredi 43890d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4390da1ce067SMiklos Szeredi return -EINVAL; 4391da1ce067SMiklos Szeredi 43920d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 43930d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4394520c8b16SMiklos Szeredi return -EINVAL; 4395520c8b16SMiklos Szeredi 43960d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 43970d7a8555SMiklos Szeredi return -EPERM; 43980d7a8555SMiklos Szeredi 4399f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4400f5beed75SAl Viro target_flags = 0; 4401f5beed75SAl Viro 4402c6a94284SJeff Layton retry: 4403f5beed75SAl Viro from = user_path_parent(olddfd, oldname, 4404f5beed75SAl Viro &old_path, &old_last, &old_type, lookup_flags); 440591a27b2aSJeff Layton if (IS_ERR(from)) { 440691a27b2aSJeff Layton error = PTR_ERR(from); 44071da177e4SLinus Torvalds goto exit; 440891a27b2aSJeff Layton } 44091da177e4SLinus Torvalds 4410f5beed75SAl Viro to = user_path_parent(newdfd, newname, 4411f5beed75SAl Viro &new_path, &new_last, &new_type, lookup_flags); 441291a27b2aSJeff Layton if (IS_ERR(to)) { 441391a27b2aSJeff Layton error = PTR_ERR(to); 44141da177e4SLinus Torvalds goto exit1; 441591a27b2aSJeff Layton } 44161da177e4SLinus Torvalds 44171da177e4SLinus Torvalds error = -EXDEV; 4418f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 44191da177e4SLinus Torvalds goto exit2; 44201da177e4SLinus Torvalds 44211da177e4SLinus Torvalds error = -EBUSY; 4422f5beed75SAl Viro if (old_type != LAST_NORM) 44231da177e4SLinus Torvalds goto exit2; 44241da177e4SLinus Torvalds 44250a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 44260a7c3937SMiklos Szeredi error = -EEXIST; 4427f5beed75SAl Viro if (new_type != LAST_NORM) 44281da177e4SLinus Torvalds goto exit2; 44291da177e4SLinus Torvalds 4430f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4431c30dabfeSJan Kara if (error) 4432c30dabfeSJan Kara goto exit2; 4433c30dabfeSJan Kara 44348e6d782cSJ. Bruce Fields retry_deleg: 4435f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 44361da177e4SLinus Torvalds 4437f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 44381da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 44391da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 44401da177e4SLinus Torvalds goto exit3; 44411da177e4SLinus Torvalds /* source must exist */ 44421da177e4SLinus Torvalds error = -ENOENT; 4443b18825a7SDavid Howells if (d_is_negative(old_dentry)) 44441da177e4SLinus Torvalds goto exit4; 4445f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 44461da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 44471da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 44481da177e4SLinus Torvalds goto exit4; 44490a7c3937SMiklos Szeredi error = -EEXIST; 44500a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 44510a7c3937SMiklos Szeredi goto exit5; 4452da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4453da1ce067SMiklos Szeredi error = -ENOENT; 4454da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4455da1ce067SMiklos Szeredi goto exit5; 4456da1ce067SMiklos Szeredi 4457da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4458da1ce067SMiklos Szeredi error = -ENOTDIR; 4459f5beed75SAl Viro if (new_last.name[new_last.len]) 4460da1ce067SMiklos Szeredi goto exit5; 4461da1ce067SMiklos Szeredi } 4462da1ce067SMiklos Szeredi } 44630a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 44640a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 44650a7c3937SMiklos Szeredi error = -ENOTDIR; 4466f5beed75SAl Viro if (old_last.name[old_last.len]) 44670a7c3937SMiklos Szeredi goto exit5; 4468f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 44690a7c3937SMiklos Szeredi goto exit5; 44700a7c3937SMiklos Szeredi } 44710a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 44720a7c3937SMiklos Szeredi error = -EINVAL; 44730a7c3937SMiklos Szeredi if (old_dentry == trap) 44740a7c3937SMiklos Szeredi goto exit5; 44751da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4476da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 44771da177e4SLinus Torvalds error = -ENOTEMPTY; 44781da177e4SLinus Torvalds if (new_dentry == trap) 44791da177e4SLinus Torvalds goto exit5; 44801da177e4SLinus Torvalds 4481f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4482f5beed75SAl Viro &new_path, new_dentry, flags); 4483be6d3e56SKentaro Takeda if (error) 4484c30dabfeSJan Kara goto exit5; 4485f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4486f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4487520c8b16SMiklos Szeredi &delegated_inode, flags); 44881da177e4SLinus Torvalds exit5: 44891da177e4SLinus Torvalds dput(new_dentry); 44901da177e4SLinus Torvalds exit4: 44911da177e4SLinus Torvalds dput(old_dentry); 44921da177e4SLinus Torvalds exit3: 4493f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 44948e6d782cSJ. Bruce Fields if (delegated_inode) { 44958e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 44968e6d782cSJ. Bruce Fields if (!error) 44978e6d782cSJ. Bruce Fields goto retry_deleg; 44988e6d782cSJ. Bruce Fields } 4499f5beed75SAl Viro mnt_drop_write(old_path.mnt); 45001da177e4SLinus Torvalds exit2: 4501c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4502c6a94284SJeff Layton should_retry = true; 4503f5beed75SAl Viro path_put(&new_path); 45042ad94ae6SAl Viro putname(to); 45051da177e4SLinus Torvalds exit1: 4506f5beed75SAl Viro path_put(&old_path); 45071da177e4SLinus Torvalds putname(from); 4508c6a94284SJeff Layton if (should_retry) { 4509c6a94284SJeff Layton should_retry = false; 4510c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4511c6a94284SJeff Layton goto retry; 4512c6a94284SJeff Layton } 45132ad94ae6SAl Viro exit: 45141da177e4SLinus Torvalds return error; 45151da177e4SLinus Torvalds } 45161da177e4SLinus Torvalds 4517520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4518520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4519520c8b16SMiklos Szeredi { 4520520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4521520c8b16SMiklos Szeredi } 4522520c8b16SMiklos Szeredi 4523a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 45245590ff0dSUlrich Drepper { 4525520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 45265590ff0dSUlrich Drepper } 45275590ff0dSUlrich Drepper 4528787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4529787fb6bcSMiklos Szeredi { 4530787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4531787fb6bcSMiklos Szeredi if (error) 4532787fb6bcSMiklos Szeredi return error; 4533787fb6bcSMiklos Szeredi 4534787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4535787fb6bcSMiklos Szeredi return -EPERM; 4536787fb6bcSMiklos Szeredi 4537787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4538787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4539787fb6bcSMiklos Szeredi } 4540787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4541787fb6bcSMiklos Szeredi 45425d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 45431da177e4SLinus Torvalds { 45445d826c84SAl Viro int len = PTR_ERR(link); 45451da177e4SLinus Torvalds if (IS_ERR(link)) 45461da177e4SLinus Torvalds goto out; 45471da177e4SLinus Torvalds 45481da177e4SLinus Torvalds len = strlen(link); 45491da177e4SLinus Torvalds if (len > (unsigned) buflen) 45501da177e4SLinus Torvalds len = buflen; 45511da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 45521da177e4SLinus Torvalds len = -EFAULT; 45531da177e4SLinus Torvalds out: 45541da177e4SLinus Torvalds return len; 45551da177e4SLinus Torvalds } 45565d826c84SAl Viro EXPORT_SYMBOL(readlink_copy); 45571da177e4SLinus Torvalds 45581da177e4SLinus Torvalds /* 45591da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 45601da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 45611da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 45621da177e4SLinus Torvalds */ 45631da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 45641da177e4SLinus Torvalds { 4565cc314eefSLinus Torvalds void *cookie; 45665f2c4179SAl Viro struct inode *inode = d_inode(dentry); 45675f2c4179SAl Viro const char *link = inode->i_link; 4568694a1764SMarcin Slusarz int res; 4569cc314eefSLinus Torvalds 4570d4dee48bSAl Viro if (!link) { 45715f2c4179SAl Viro link = inode->i_op->follow_link(dentry, &cookie); 4572680baacbSAl Viro if (IS_ERR(link)) 4573680baacbSAl Viro return PTR_ERR(link); 4574d4dee48bSAl Viro } 4575680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 45765f2c4179SAl Viro if (inode->i_op->put_link) 45775f2c4179SAl Viro inode->i_op->put_link(inode, cookie); 4578694a1764SMarcin Slusarz return res; 45791da177e4SLinus Torvalds } 45804d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 45811da177e4SLinus Torvalds 45821da177e4SLinus Torvalds /* get the link contents into pagecache */ 45831da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 45841da177e4SLinus Torvalds { 4585ebd09abbSDuane Griffin char *kaddr; 45861da177e4SLinus Torvalds struct page *page; 45871da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 4588090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 45891da177e4SLinus Torvalds if (IS_ERR(page)) 45906fe6900eSNick Piggin return (char*)page; 45911da177e4SLinus Torvalds *ppage = page; 4592ebd09abbSDuane Griffin kaddr = kmap(page); 4593ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 4594ebd09abbSDuane Griffin return kaddr; 45951da177e4SLinus Torvalds } 45961da177e4SLinus Torvalds 45971da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 45981da177e4SLinus Torvalds { 45991da177e4SLinus Torvalds struct page *page = NULL; 46005d826c84SAl Viro int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); 46011da177e4SLinus Torvalds if (page) { 46021da177e4SLinus Torvalds kunmap(page); 46031da177e4SLinus Torvalds page_cache_release(page); 46041da177e4SLinus Torvalds } 46051da177e4SLinus Torvalds return res; 46061da177e4SLinus Torvalds } 46074d359507SAl Viro EXPORT_SYMBOL(page_readlink); 46081da177e4SLinus Torvalds 46096e77137bSAl Viro const char *page_follow_link_light(struct dentry *dentry, void **cookie) 46101da177e4SLinus Torvalds { 4611cc314eefSLinus Torvalds struct page *page = NULL; 4612680baacbSAl Viro char *res = page_getlink(dentry, &page); 4613680baacbSAl Viro if (!IS_ERR(res)) 4614680baacbSAl Viro *cookie = page; 4615680baacbSAl Viro return res; 46161da177e4SLinus Torvalds } 46174d359507SAl Viro EXPORT_SYMBOL(page_follow_link_light); 46181da177e4SLinus Torvalds 46195f2c4179SAl Viro void page_put_link(struct inode *unused, void *cookie) 46201da177e4SLinus Torvalds { 4621cc314eefSLinus Torvalds struct page *page = cookie; 46221da177e4SLinus Torvalds kunmap(page); 46231da177e4SLinus Torvalds page_cache_release(page); 46241da177e4SLinus Torvalds } 46254d359507SAl Viro EXPORT_SYMBOL(page_put_link); 46261da177e4SLinus Torvalds 462754566b2cSNick Piggin /* 462854566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 462954566b2cSNick Piggin */ 463054566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 46311da177e4SLinus Torvalds { 46321da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 46330adb25d2SKirill Korotaev struct page *page; 4634afddba49SNick Piggin void *fsdata; 4635beb497abSDmitriy Monakhov int err; 46361da177e4SLinus Torvalds char *kaddr; 463754566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 463854566b2cSNick Piggin if (nofs) 463954566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 46401da177e4SLinus Torvalds 46417e53cac4SNeilBrown retry: 4642afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 464354566b2cSNick Piggin flags, &page, &fsdata); 46441da177e4SLinus Torvalds if (err) 4645afddba49SNick Piggin goto fail; 4646afddba49SNick Piggin 4647e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 46481da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 4649e8e3c3d6SCong Wang kunmap_atomic(kaddr); 4650afddba49SNick Piggin 4651afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4652afddba49SNick Piggin page, fsdata); 46531da177e4SLinus Torvalds if (err < 0) 46541da177e4SLinus Torvalds goto fail; 4655afddba49SNick Piggin if (err < len-1) 4656afddba49SNick Piggin goto retry; 4657afddba49SNick Piggin 46581da177e4SLinus Torvalds mark_inode_dirty(inode); 46591da177e4SLinus Torvalds return 0; 46601da177e4SLinus Torvalds fail: 46611da177e4SLinus Torvalds return err; 46621da177e4SLinus Torvalds } 46634d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 46641da177e4SLinus Torvalds 46650adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 46660adb25d2SKirill Korotaev { 46670adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4668c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 46690adb25d2SKirill Korotaev } 46704d359507SAl Viro EXPORT_SYMBOL(page_symlink); 46710adb25d2SKirill Korotaev 467292e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 46731da177e4SLinus Torvalds .readlink = generic_readlink, 46741da177e4SLinus Torvalds .follow_link = page_follow_link_light, 46751da177e4SLinus Torvalds .put_link = page_put_link, 46761da177e4SLinus Torvalds }; 46771da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 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