11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namei.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Some corrections by tytso. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 121da177e4SLinus Torvalds * lookup logic. 131da177e4SLinus Torvalds */ 141da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 151da177e4SLinus Torvalds */ 161da177e4SLinus Torvalds 171da177e4SLinus Torvalds #include <linux/init.h> 18630d9c47SPaul Gortmaker #include <linux/export.h> 1944696908SDavid S. Miller #include <linux/kernel.h> 201da177e4SLinus Torvalds #include <linux/slab.h> 211da177e4SLinus Torvalds #include <linux/fs.h> 221da177e4SLinus Torvalds #include <linux/namei.h> 231da177e4SLinus Torvalds #include <linux/pagemap.h> 240eeca283SRobert Love #include <linux/fsnotify.h> 251da177e4SLinus Torvalds #include <linux/personality.h> 261da177e4SLinus Torvalds #include <linux/security.h> 276146f0d5SMimi Zohar #include <linux/ima.h> 281da177e4SLinus Torvalds #include <linux/syscalls.h> 291da177e4SLinus Torvalds #include <linux/mount.h> 301da177e4SLinus Torvalds #include <linux/audit.h> 3116f7e0feSRandy Dunlap #include <linux/capability.h> 32834f2a4aSTrond Myklebust #include <linux/file.h> 335590ff0dSUlrich Drepper #include <linux/fcntl.h> 3408ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 355ad4e53bSAl Viro #include <linux/fs_struct.h> 36e77819e5SLinus Torvalds #include <linux/posix_acl.h> 3799d263d4SLinus Torvalds #include <linux/hash.h> 381da177e4SLinus Torvalds #include <asm/uaccess.h> 391da177e4SLinus Torvalds 40e81e3f4dSEric Paris #include "internal.h" 41c7105365SAl Viro #include "mount.h" 42e81e3f4dSEric Paris 431da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 441da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 451da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 461da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 471da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 481da177e4SLinus Torvalds * 491da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 501da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 511da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 521da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 531da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 541da177e4SLinus Torvalds * the special cases of the former code. 551da177e4SLinus Torvalds * 561da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 571da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 581da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 591da177e4SLinus Torvalds * 601da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 611da177e4SLinus Torvalds * resolution to correspond with current state of the code. 621da177e4SLinus Torvalds * 631da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 641da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 651da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 661da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 671da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 681da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 691da177e4SLinus Torvalds */ 701da177e4SLinus Torvalds 711da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 721da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 731da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 741da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 751da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 761da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7725985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 781da177e4SLinus Torvalds * 791da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 801da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 811da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 821da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 831da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 841da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 851da177e4SLinus Torvalds * and in the old Linux semantics. 861da177e4SLinus Torvalds */ 871da177e4SLinus Torvalds 881da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 891da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 901da177e4SLinus Torvalds * 911da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 921da177e4SLinus Torvalds */ 931da177e4SLinus Torvalds 941da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 951da177e4SLinus Torvalds * inside the path - always follow. 961da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 971da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 981da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 991da177e4SLinus Torvalds * otherwise - don't follow. 1001da177e4SLinus Torvalds * (applied in that order). 1011da177e4SLinus Torvalds * 1021da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1031da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1041da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1051da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1061da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1071da177e4SLinus Torvalds */ 1081da177e4SLinus Torvalds /* 1091da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 110a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1111da177e4SLinus Torvalds * any extra contention... 1121da177e4SLinus Torvalds */ 1131da177e4SLinus Torvalds 1141da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1151da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1161da177e4SLinus Torvalds * kernel data space before using them.. 1171da177e4SLinus Torvalds * 1181da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1191da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1201da177e4SLinus Torvalds */ 1217950e385SJeff Layton 122fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12391a27b2aSJeff Layton 12451f39a1fSDavid Drysdale struct filename * 12591a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12691a27b2aSJeff Layton { 12794b5d262SAl Viro struct filename *result; 1287950e385SJeff Layton char *kname; 12994b5d262SAl Viro int len; 1301da177e4SLinus Torvalds 1317ac86265SJeff Layton result = audit_reusename(filename); 1327ac86265SJeff Layton if (result) 1337ac86265SJeff Layton return result; 1347ac86265SJeff Layton 1357950e385SJeff Layton result = __getname(); 1363f9f0aa6SLinus Torvalds if (unlikely(!result)) 1374043cde8SEric Paris return ERR_PTR(-ENOMEM); 1381da177e4SLinus Torvalds 1397950e385SJeff Layton /* 1407950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1417950e385SJeff Layton * allocation 1427950e385SJeff Layton */ 143fd2f7cb5SAl Viro kname = (char *)result->iname; 14491a27b2aSJeff Layton result->name = kname; 1457950e385SJeff Layton 14694b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 14791a27b2aSJeff Layton if (unlikely(len < 0)) { 14894b5d262SAl Viro __putname(result); 14994b5d262SAl Viro return ERR_PTR(len); 15091a27b2aSJeff Layton } 1513f9f0aa6SLinus Torvalds 1527950e385SJeff Layton /* 1537950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1547950e385SJeff Layton * separate struct filename so we can dedicate the entire 1557950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1567950e385SJeff Layton * userland. 1577950e385SJeff Layton */ 15894b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 159fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1607950e385SJeff Layton kname = (char *)result; 1617950e385SJeff Layton 162fd2f7cb5SAl Viro /* 163fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 164fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 165fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 166fd2f7cb5SAl Viro */ 167fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 16894b5d262SAl Viro if (unlikely(!result)) { 16994b5d262SAl Viro __putname(kname); 17094b5d262SAl Viro return ERR_PTR(-ENOMEM); 1717950e385SJeff Layton } 1727950e385SJeff Layton result->name = kname; 17394b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17494b5d262SAl Viro if (unlikely(len < 0)) { 17594b5d262SAl Viro __putname(kname); 17694b5d262SAl Viro kfree(result); 17794b5d262SAl Viro return ERR_PTR(len); 17894b5d262SAl Viro } 17994b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18094b5d262SAl Viro __putname(kname); 18194b5d262SAl Viro kfree(result); 18294b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18394b5d262SAl Viro } 1847950e385SJeff Layton } 1857950e385SJeff Layton 18694b5d262SAl Viro result->refcnt = 1; 1873f9f0aa6SLinus Torvalds /* The empty path is special. */ 1883f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1893f9f0aa6SLinus Torvalds if (empty) 1901fa1e7f6SAndy Whitcroft *empty = 1; 19194b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19294b5d262SAl Viro putname(result); 19394b5d262SAl Viro return ERR_PTR(-ENOENT); 1941da177e4SLinus Torvalds } 19594b5d262SAl Viro } 1967950e385SJeff Layton 1977950e385SJeff Layton result->uptr = filename; 198c4ad8f98SLinus Torvalds result->aname = NULL; 1991da177e4SLinus Torvalds audit_getname(result); 2001da177e4SLinus Torvalds return result; 2013f9f0aa6SLinus Torvalds } 2023f9f0aa6SLinus Torvalds 20391a27b2aSJeff Layton struct filename * 20491a27b2aSJeff Layton getname(const char __user * filename) 205f52e0c11SAl Viro { 206f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 207f52e0c11SAl Viro } 208f52e0c11SAl Viro 209c4ad8f98SLinus Torvalds struct filename * 210c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 211c4ad8f98SLinus Torvalds { 212c4ad8f98SLinus Torvalds struct filename *result; 21308518549SPaul Moore int len = strlen(filename) + 1; 214c4ad8f98SLinus Torvalds 215c4ad8f98SLinus Torvalds result = __getname(); 216c4ad8f98SLinus Torvalds if (unlikely(!result)) 217c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 218c4ad8f98SLinus Torvalds 21908518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 220fd2f7cb5SAl Viro result->name = (char *)result->iname; 22108518549SPaul Moore } else if (len <= PATH_MAX) { 22208518549SPaul Moore struct filename *tmp; 22308518549SPaul Moore 22408518549SPaul Moore tmp = kmalloc(sizeof(*tmp), GFP_KERNEL); 22508518549SPaul Moore if (unlikely(!tmp)) { 22608518549SPaul Moore __putname(result); 22708518549SPaul Moore return ERR_PTR(-ENOMEM); 22808518549SPaul Moore } 22908518549SPaul Moore tmp->name = (char *)result; 23008518549SPaul Moore result = tmp; 23108518549SPaul Moore } else { 23208518549SPaul Moore __putname(result); 23308518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23408518549SPaul Moore } 23508518549SPaul Moore memcpy((char *)result->name, filename, len); 236c4ad8f98SLinus Torvalds result->uptr = NULL; 237c4ad8f98SLinus Torvalds result->aname = NULL; 23855422d0bSPaul Moore result->refcnt = 1; 239fd3522fdSPaul Moore audit_getname(result); 240c4ad8f98SLinus Torvalds 241c4ad8f98SLinus Torvalds return result; 242c4ad8f98SLinus Torvalds } 243c4ad8f98SLinus Torvalds 24491a27b2aSJeff Layton void putname(struct filename *name) 2451da177e4SLinus Torvalds { 24655422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 24755422d0bSPaul Moore 24855422d0bSPaul Moore if (--name->refcnt > 0) 24955422d0bSPaul Moore return; 25055422d0bSPaul Moore 251fd2f7cb5SAl Viro if (name->name != name->iname) { 25255422d0bSPaul Moore __putname(name->name); 25355422d0bSPaul Moore kfree(name); 25455422d0bSPaul Moore } else 25555422d0bSPaul Moore __putname(name); 2561da177e4SLinus Torvalds } 2571da177e4SLinus Torvalds 258e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 259e77819e5SLinus Torvalds { 26084635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 261e77819e5SLinus Torvalds struct posix_acl *acl; 262e77819e5SLinus Torvalds 263e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2643567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2653567866bSAl Viro if (!acl) 266e77819e5SLinus Torvalds return -EAGAIN; 2673567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 2683567866bSAl Viro if (acl == ACL_NOT_CACHED) 269e77819e5SLinus Torvalds return -ECHILD; 270206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 271e77819e5SLinus Torvalds } 272e77819e5SLinus Torvalds 2732982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2744e34e719SChristoph Hellwig if (IS_ERR(acl)) 2754e34e719SChristoph Hellwig return PTR_ERR(acl); 276e77819e5SLinus Torvalds if (acl) { 277e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 278e77819e5SLinus Torvalds posix_acl_release(acl); 279e77819e5SLinus Torvalds return error; 280e77819e5SLinus Torvalds } 28184635d68SLinus Torvalds #endif 282e77819e5SLinus Torvalds 283e77819e5SLinus Torvalds return -EAGAIN; 284e77819e5SLinus Torvalds } 285e77819e5SLinus Torvalds 2865909ccaaSLinus Torvalds /* 287948409c7SAndreas Gruenbacher * This does the basic permission checking 2885909ccaaSLinus Torvalds */ 2897e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2905909ccaaSLinus Torvalds { 29126cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2925909ccaaSLinus Torvalds 2938e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2945909ccaaSLinus Torvalds mode >>= 6; 2955909ccaaSLinus Torvalds else { 296e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2977e40145eSAl Viro int error = check_acl(inode, mask); 2985909ccaaSLinus Torvalds if (error != -EAGAIN) 2995909ccaaSLinus Torvalds return error; 3005909ccaaSLinus Torvalds } 3015909ccaaSLinus Torvalds 3025909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3035909ccaaSLinus Torvalds mode >>= 3; 3045909ccaaSLinus Torvalds } 3055909ccaaSLinus Torvalds 3065909ccaaSLinus Torvalds /* 3075909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3085909ccaaSLinus Torvalds */ 3099c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3105909ccaaSLinus Torvalds return 0; 3115909ccaaSLinus Torvalds return -EACCES; 3125909ccaaSLinus Torvalds } 3131da177e4SLinus Torvalds 3141da177e4SLinus Torvalds /** 3151da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3161da177e4SLinus Torvalds * @inode: inode to check access rights for 3178fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3181da177e4SLinus Torvalds * 3191da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3201da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3211da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 322b74c79e9SNick Piggin * are used for other things. 323b74c79e9SNick Piggin * 324b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 325b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 326b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3271da177e4SLinus Torvalds */ 3282830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3291da177e4SLinus Torvalds { 3305909ccaaSLinus Torvalds int ret; 3311da177e4SLinus Torvalds 3321da177e4SLinus Torvalds /* 333948409c7SAndreas Gruenbacher * Do the basic permission checks. 3341da177e4SLinus Torvalds */ 3357e40145eSAl Viro ret = acl_permission_check(inode, mask); 3365909ccaaSLinus Torvalds if (ret != -EACCES) 3375909ccaaSLinus Torvalds return ret; 3381da177e4SLinus Torvalds 339d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 340d594e7ecSAl Viro /* DACs are overridable for directories */ 34123adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 342d594e7ecSAl Viro return 0; 343d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34423adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34523adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 346d594e7ecSAl Viro return 0; 347d594e7ecSAl Viro return -EACCES; 348d594e7ecSAl Viro } 3491da177e4SLinus Torvalds /* 3501da177e4SLinus Torvalds * Read/write DACs are always overridable. 351d594e7ecSAl Viro * Executable DACs are overridable when there is 352d594e7ecSAl Viro * at least one exec bit set. 3531da177e4SLinus Torvalds */ 354d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 35523adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3561da177e4SLinus Torvalds return 0; 3571da177e4SLinus Torvalds 3581da177e4SLinus Torvalds /* 3591da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3601da177e4SLinus Torvalds */ 3617ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 362d594e7ecSAl Viro if (mask == MAY_READ) 36323adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3641da177e4SLinus Torvalds return 0; 3651da177e4SLinus Torvalds 3661da177e4SLinus Torvalds return -EACCES; 3671da177e4SLinus Torvalds } 3684d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3691da177e4SLinus Torvalds 3703ddcd056SLinus Torvalds /* 3713ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3723ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3733ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3743ddcd056SLinus Torvalds * permission function, use the fast case". 3753ddcd056SLinus Torvalds */ 3763ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3773ddcd056SLinus Torvalds { 3783ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3793ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3803ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3813ddcd056SLinus Torvalds 3823ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3833ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3843ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3853ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3863ddcd056SLinus Torvalds } 3873ddcd056SLinus Torvalds return generic_permission(inode, mask); 3883ddcd056SLinus Torvalds } 3893ddcd056SLinus Torvalds 390cb23beb5SChristoph Hellwig /** 3910bdaea90SDavid Howells * __inode_permission - Check for access rights to a given inode 3920bdaea90SDavid Howells * @inode: Inode to check permission on 3930bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 394cb23beb5SChristoph Hellwig * 3950bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. 396948409c7SAndreas Gruenbacher * 397948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 3980bdaea90SDavid Howells * 3990bdaea90SDavid Howells * This does not check for a read-only file system. You probably want 4000bdaea90SDavid Howells * inode_permission(). 401cb23beb5SChristoph Hellwig */ 4020bdaea90SDavid Howells int __inode_permission(struct inode *inode, int mask) 4031da177e4SLinus Torvalds { 404e6305c43SAl Viro int retval; 4051da177e4SLinus Torvalds 4063ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 4071da177e4SLinus Torvalds /* 4081da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 4091da177e4SLinus Torvalds */ 4101da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 4111da177e4SLinus Torvalds return -EACCES; 4121da177e4SLinus Torvalds } 4131da177e4SLinus Torvalds 4143ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 4151da177e4SLinus Torvalds if (retval) 4161da177e4SLinus Torvalds return retval; 4171da177e4SLinus Torvalds 41808ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 41908ce5f16SSerge E. Hallyn if (retval) 42008ce5f16SSerge E. Hallyn return retval; 42108ce5f16SSerge E. Hallyn 422d09ca739SEric Paris return security_inode_permission(inode, mask); 4231da177e4SLinus Torvalds } 424bd5d0856SMiklos Szeredi EXPORT_SYMBOL(__inode_permission); 4251da177e4SLinus Torvalds 426f4d6ff89SAl Viro /** 4270bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 4280bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 42955852635SRandy Dunlap * @inode: Inode to check permission on 4300bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4310bdaea90SDavid Howells * 4320bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4330bdaea90SDavid Howells */ 4340bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4350bdaea90SDavid Howells { 4360bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4370bdaea90SDavid Howells umode_t mode = inode->i_mode; 4380bdaea90SDavid Howells 4390bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 4400bdaea90SDavid Howells if ((sb->s_flags & MS_RDONLY) && 4410bdaea90SDavid Howells (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4420bdaea90SDavid Howells return -EROFS; 4430bdaea90SDavid Howells } 4440bdaea90SDavid Howells return 0; 4450bdaea90SDavid Howells } 4460bdaea90SDavid Howells 4470bdaea90SDavid Howells /** 4480bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4490bdaea90SDavid Howells * @inode: Inode to check permission on 4500bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4510bdaea90SDavid Howells * 4520bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4530bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4540bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4550bdaea90SDavid Howells * 4560bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4570bdaea90SDavid Howells */ 4580bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4590bdaea90SDavid Howells { 4600bdaea90SDavid Howells int retval; 4610bdaea90SDavid Howells 4620bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4630bdaea90SDavid Howells if (retval) 4640bdaea90SDavid Howells return retval; 4650bdaea90SDavid Howells return __inode_permission(inode, mask); 4660bdaea90SDavid Howells } 4674d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4680bdaea90SDavid Howells 4690bdaea90SDavid Howells /** 4705dd784d0SJan Blunck * path_get - get a reference to a path 4715dd784d0SJan Blunck * @path: path to get the reference to 4725dd784d0SJan Blunck * 4735dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4745dd784d0SJan Blunck */ 475dcf787f3SAl Viro void path_get(const struct path *path) 4765dd784d0SJan Blunck { 4775dd784d0SJan Blunck mntget(path->mnt); 4785dd784d0SJan Blunck dget(path->dentry); 4795dd784d0SJan Blunck } 4805dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4815dd784d0SJan Blunck 4825dd784d0SJan Blunck /** 4831d957f9bSJan Blunck * path_put - put a reference to a path 4841d957f9bSJan Blunck * @path: path to put the reference to 4851d957f9bSJan Blunck * 4861d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4871d957f9bSJan Blunck */ 488dcf787f3SAl Viro void path_put(const struct path *path) 4891da177e4SLinus Torvalds { 4901d957f9bSJan Blunck dput(path->dentry); 4911d957f9bSJan Blunck mntput(path->mnt); 4921da177e4SLinus Torvalds } 4931d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4941da177e4SLinus Torvalds 495894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 4961f55a6ecSAl Viro struct nameidata { 4971f55a6ecSAl Viro struct path path; 4981f55a6ecSAl Viro struct qstr last; 4991f55a6ecSAl Viro struct path root; 5001f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 5011f55a6ecSAl Viro unsigned int flags; 5021f55a6ecSAl Viro unsigned seq, m_seq; 5031f55a6ecSAl Viro int last_type; 5041f55a6ecSAl Viro unsigned depth; 505756daf26SNeilBrown int total_link_count; 506697fc6caSAl Viro struct saved { 507697fc6caSAl Viro struct path link; 508697fc6caSAl Viro void *cookie; 509697fc6caSAl Viro const char *name; 510237d8b32SAl Viro struct inode *inode; 5110450b2d1SAl Viro unsigned seq; 512894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5131f55a6ecSAl Viro }; 5141f55a6ecSAl Viro 515756daf26SNeilBrown static struct nameidata *set_nameidata(struct nameidata *p) 516894bc8c4SAl Viro { 517756daf26SNeilBrown struct nameidata *old = current->nameidata; 518756daf26SNeilBrown p->stack = p->internal; 519756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 520756daf26SNeilBrown current->nameidata = p; 521756daf26SNeilBrown return old; 522894bc8c4SAl Viro } 523894bc8c4SAl Viro 524756daf26SNeilBrown static void restore_nameidata(struct nameidata *old) 525894bc8c4SAl Viro { 526756daf26SNeilBrown struct nameidata *now = current->nameidata; 527756daf26SNeilBrown 528756daf26SNeilBrown current->nameidata = old; 529756daf26SNeilBrown if (old) 530756daf26SNeilBrown old->total_link_count = now->total_link_count; 531756daf26SNeilBrown if (now->stack != now->internal) { 532756daf26SNeilBrown kfree(now->stack); 533756daf26SNeilBrown now->stack = now->internal; 534894bc8c4SAl Viro } 535894bc8c4SAl Viro } 536894bc8c4SAl Viro 537894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 538894bc8c4SAl Viro { 539bc40aee0SAl Viro struct saved *p; 540bc40aee0SAl Viro 541bc40aee0SAl Viro if (nd->flags & LOOKUP_RCU) { 542bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 543bc40aee0SAl Viro GFP_ATOMIC); 544bc40aee0SAl Viro if (unlikely(!p)) 545bc40aee0SAl Viro return -ECHILD; 546bc40aee0SAl Viro } else { 547bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 548894bc8c4SAl Viro GFP_KERNEL); 549894bc8c4SAl Viro if (unlikely(!p)) 550894bc8c4SAl Viro return -ENOMEM; 551bc40aee0SAl Viro } 552894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 553894bc8c4SAl Viro nd->stack = p; 554894bc8c4SAl Viro return 0; 555894bc8c4SAl Viro } 556894bc8c4SAl Viro 557894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 558894bc8c4SAl Viro { 559da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 560894bc8c4SAl Viro return 0; 561894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 562894bc8c4SAl Viro return 0; 563894bc8c4SAl Viro return __nd_alloc_stack(nd); 564894bc8c4SAl Viro } 565894bc8c4SAl Viro 5667973387aSAl Viro static void drop_links(struct nameidata *nd) 5677973387aSAl Viro { 5687973387aSAl Viro int i = nd->depth; 5697973387aSAl Viro while (i--) { 5707973387aSAl Viro struct saved *last = nd->stack + i; 5717973387aSAl Viro struct inode *inode = last->inode; 5727973387aSAl Viro if (last->cookie && inode->i_op->put_link) { 5737973387aSAl Viro inode->i_op->put_link(inode, last->cookie); 5747973387aSAl Viro last->cookie = NULL; 5757973387aSAl Viro } 5767973387aSAl Viro } 5777973387aSAl Viro } 5787973387aSAl Viro 5797973387aSAl Viro static void terminate_walk(struct nameidata *nd) 5807973387aSAl Viro { 5817973387aSAl Viro drop_links(nd); 5827973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 5837973387aSAl Viro int i; 5847973387aSAl Viro path_put(&nd->path); 5857973387aSAl Viro for (i = 0; i < nd->depth; i++) 5867973387aSAl Viro path_put(&nd->stack[i].link); 5877973387aSAl Viro } else { 5887973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 5897973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 5907973387aSAl Viro nd->root.mnt = NULL; 5917973387aSAl Viro rcu_read_unlock(); 5927973387aSAl Viro } 5937973387aSAl Viro nd->depth = 0; 5947973387aSAl Viro } 5957973387aSAl Viro 5967973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 5977973387aSAl Viro static bool legitimize_path(struct nameidata *nd, 5987973387aSAl Viro struct path *path, unsigned seq) 5997973387aSAl Viro { 6007973387aSAl Viro int res = __legitimize_mnt(path->mnt, nd->m_seq); 6017973387aSAl Viro if (unlikely(res)) { 6027973387aSAl Viro if (res > 0) 6037973387aSAl Viro path->mnt = NULL; 6047973387aSAl Viro path->dentry = NULL; 6057973387aSAl Viro return false; 6067973387aSAl Viro } 6077973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 6087973387aSAl Viro path->dentry = NULL; 6097973387aSAl Viro return false; 6107973387aSAl Viro } 6117973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6127973387aSAl Viro } 6137973387aSAl Viro 6147973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6157973387aSAl Viro { 6167973387aSAl Viro int i; 6177973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6187973387aSAl Viro struct saved *last = nd->stack + i; 6197973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6207973387aSAl Viro drop_links(nd); 6217973387aSAl Viro nd->depth = i + 1; 6227973387aSAl Viro return false; 6237973387aSAl Viro } 6247973387aSAl Viro } 6257973387aSAl Viro return true; 6267973387aSAl Viro } 6277973387aSAl Viro 62819660af7SAl Viro /* 62931e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 63019660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 63119660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 63219660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 63319660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 63419660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 63519660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 63619660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 63731e6b01fSNick Piggin */ 63831e6b01fSNick Piggin 63931e6b01fSNick Piggin /** 64019660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 64119660af7SAl Viro * @nd: nameidata pathwalk data 64219660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 6436e9918b7SAl Viro * @seq: seq number to check dentry against 64439191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 64531e6b01fSNick Piggin * 64619660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 64719660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 64819660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 6497973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6507973387aSAl Viro * terminate_walk(). 65131e6b01fSNick Piggin */ 6526e9918b7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry, unsigned seq) 65331e6b01fSNick Piggin { 65431e6b01fSNick Piggin struct fs_struct *fs = current->fs; 65531e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 65631e6b01fSNick Piggin 65731e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 658e5c832d5SLinus Torvalds 659e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6607973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6617973387aSAl Viro goto out2; 6627973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 6637973387aSAl Viro goto out2; 6647973387aSAl Viro if (unlikely(!lockref_get_not_dead(&parent->d_lockref))) 6657973387aSAl Viro goto out1; 66648a066e7SAl Viro 66715570086SLinus Torvalds /* 66815570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 66915570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 67015570086SLinus Torvalds * 67115570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 67215570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 67315570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 67415570086SLinus Torvalds * since we checked the sequence number of the parent after we got 67515570086SLinus Torvalds * the child sequence number. So we know the parent must still 67615570086SLinus Torvalds * be valid if the child sequence number is still valid. 67715570086SLinus Torvalds */ 67819660af7SAl Viro if (!dentry) { 679e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 680e5c832d5SLinus Torvalds goto out; 68119660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 68219660af7SAl Viro } else { 683e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 684e5c832d5SLinus Torvalds goto out; 6856e9918b7SAl Viro if (read_seqcount_retry(&dentry->d_seq, seq)) 686e5c832d5SLinus Torvalds goto drop_dentry; 68719660af7SAl Viro } 688e5c832d5SLinus Torvalds 689e5c832d5SLinus Torvalds /* 690e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 691e5c832d5SLinus Torvalds * still valid and get it if required. 692e5c832d5SLinus Torvalds */ 693e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 694e5c832d5SLinus Torvalds spin_lock(&fs->lock); 6957973387aSAl Viro if (unlikely(!path_equal(&nd->root, &fs->root))) { 6967973387aSAl Viro spin_unlock(&fs->lock); 6977973387aSAl Viro goto drop_dentry; 6987973387aSAl Viro } 69931e6b01fSNick Piggin path_get(&nd->root); 70031e6b01fSNick Piggin spin_unlock(&fs->lock); 70131e6b01fSNick Piggin } 70231e6b01fSNick Piggin 7038b61e74fSAl Viro rcu_read_unlock(); 70431e6b01fSNick Piggin return 0; 70519660af7SAl Viro 706e5c832d5SLinus Torvalds drop_dentry: 7078b61e74fSAl Viro rcu_read_unlock(); 708e5c832d5SLinus Torvalds dput(dentry); 709d0d27277SLinus Torvalds goto drop_root_mnt; 7107973387aSAl Viro out2: 7117973387aSAl Viro nd->path.mnt = NULL; 7127973387aSAl Viro out1: 7137973387aSAl Viro nd->path.dentry = NULL; 714e5c832d5SLinus Torvalds out: 7158b61e74fSAl Viro rcu_read_unlock(); 716d0d27277SLinus Torvalds drop_root_mnt: 717d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 718d0d27277SLinus Torvalds nd->root.mnt = NULL; 71931e6b01fSNick Piggin return -ECHILD; 72031e6b01fSNick Piggin } 72131e6b01fSNick Piggin 7227973387aSAl Viro static int unlazy_link(struct nameidata *nd, struct path *link, unsigned seq) 7237973387aSAl Viro { 7247973387aSAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 7257973387aSAl Viro drop_links(nd); 7267973387aSAl Viro nd->depth = 0; 7277973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 7287973387aSAl Viro nd->path.mnt = NULL; 7297973387aSAl Viro nd->path.dentry = NULL; 7307973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7317973387aSAl Viro nd->root.mnt = NULL; 7327973387aSAl Viro rcu_read_unlock(); 7337973387aSAl Viro } else if (likely(unlazy_walk(nd, NULL, 0)) == 0) { 7347973387aSAl Viro return 0; 7357973387aSAl Viro } 7367973387aSAl Viro path_put(link); 7377973387aSAl Viro return -ECHILD; 7387973387aSAl Viro } 7397973387aSAl Viro 7404ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 74134286d66SNick Piggin { 7424ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 74334286d66SNick Piggin } 74434286d66SNick Piggin 7459f1fafeeSAl Viro /** 7469f1fafeeSAl Viro * complete_walk - successful completion of path walk 7479f1fafeeSAl Viro * @nd: pointer nameidata 74839159de2SJeff Layton * 7499f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7509f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7519f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7529f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7539f1fafeeSAl Viro * need to drop nd->path. 75439159de2SJeff Layton */ 7559f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 75639159de2SJeff Layton { 75716c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 75839159de2SJeff Layton int status; 75939159de2SJeff Layton 7609f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 7619f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7629f1fafeeSAl Viro nd->root.mnt = NULL; 7636e9918b7SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 76448a066e7SAl Viro return -ECHILD; 76548a066e7SAl Viro } 7669f1fafeeSAl Viro 76716c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 76839159de2SJeff Layton return 0; 76939159de2SJeff Layton 770ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 77116c2cd71SAl Viro return 0; 77216c2cd71SAl Viro 773ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 77439159de2SJeff Layton if (status > 0) 77539159de2SJeff Layton return 0; 77639159de2SJeff Layton 77716c2cd71SAl Viro if (!status) 77839159de2SJeff Layton status = -ESTALE; 77916c2cd71SAl Viro 78039159de2SJeff Layton return status; 78139159de2SJeff Layton } 78239159de2SJeff Layton 7832a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 7842a737871SAl Viro { 785f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 7862a737871SAl Viro } 7872a737871SAl Viro 7887bd88377SAl Viro static __always_inline unsigned set_root_rcu(struct nameidata *nd) 78931e6b01fSNick Piggin { 79031e6b01fSNick Piggin struct fs_struct *fs = current->fs; 7917bd88377SAl Viro unsigned seq, res; 792c28cc364SNick Piggin 793c28cc364SNick Piggin do { 794c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 79531e6b01fSNick Piggin nd->root = fs->root; 7967bd88377SAl Viro res = __read_seqcount_begin(&nd->root.dentry->d_seq); 797c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 7987bd88377SAl Viro return res; 79931e6b01fSNick Piggin } 80031e6b01fSNick Piggin 8011d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 802051d3812SIan Kent { 803051d3812SIan Kent dput(path->dentry); 8044ac91378SJan Blunck if (path->mnt != nd->path.mnt) 805051d3812SIan Kent mntput(path->mnt); 806051d3812SIan Kent } 807051d3812SIan Kent 8087b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8097b9337aaSNick Piggin struct nameidata *nd) 810051d3812SIan Kent { 81131e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8124ac91378SJan Blunck dput(nd->path.dentry); 81331e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8144ac91378SJan Blunck mntput(nd->path.mnt); 8159a229683SHuang Shijie } 81631e6b01fSNick Piggin nd->path.mnt = path->mnt; 8174ac91378SJan Blunck nd->path.dentry = path->dentry; 818051d3812SIan Kent } 819051d3812SIan Kent 820b5fb63c1SChristoph Hellwig /* 821b5fb63c1SChristoph Hellwig * Helper to directly jump to a known parsed path from ->follow_link, 822b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 823b5fb63c1SChristoph Hellwig */ 8246e77137bSAl Viro void nd_jump_link(struct path *path) 825b5fb63c1SChristoph Hellwig { 8266e77137bSAl Viro struct nameidata *nd = current->nameidata; 827b5fb63c1SChristoph Hellwig path_put(&nd->path); 828b5fb63c1SChristoph Hellwig 829b5fb63c1SChristoph Hellwig nd->path = *path; 830b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 831b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 832b5fb63c1SChristoph Hellwig } 833b5fb63c1SChristoph Hellwig 834b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 835574197e0SAl Viro { 83621c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 837237d8b32SAl Viro struct inode *inode = last->inode; 838b9ff4429SAl Viro if (last->cookie && inode->i_op->put_link) 8395f2c4179SAl Viro inode->i_op->put_link(inode, last->cookie); 8406548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 841b9ff4429SAl Viro path_put(&last->link); 842574197e0SAl Viro } 843574197e0SAl Viro 844561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 845561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 846800179c9SKees Cook 847800179c9SKees Cook /** 848800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 84955852635SRandy Dunlap * @nd: nameidata pathwalk data 850800179c9SKees Cook * 851800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 852800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 853800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 854800179c9SKees Cook * processes from failing races against path names that may change out 855800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 856800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 857800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 858800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 859800179c9SKees Cook * 860800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 861800179c9SKees Cook */ 862fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 863800179c9SKees Cook { 864800179c9SKees Cook const struct inode *inode; 865800179c9SKees Cook const struct inode *parent; 866800179c9SKees Cook 867800179c9SKees Cook if (!sysctl_protected_symlinks) 868800179c9SKees Cook return 0; 869800179c9SKees Cook 870800179c9SKees Cook /* Allowed if owner and follower match. */ 871237d8b32SAl Viro inode = nd->stack[0].inode; 87281abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 873800179c9SKees Cook return 0; 874800179c9SKees Cook 875800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 876800179c9SKees Cook parent = nd->path.dentry->d_inode; 877800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 878800179c9SKees Cook return 0; 879800179c9SKees Cook 880800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 88181abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 882800179c9SKees Cook return 0; 883800179c9SKees Cook 88431956502SAl Viro if (nd->flags & LOOKUP_RCU) 88531956502SAl Viro return -ECHILD; 88631956502SAl Viro 8871cf2665bSAl Viro audit_log_link_denied("follow_link", &nd->stack[0].link); 888800179c9SKees Cook return -EACCES; 889800179c9SKees Cook } 890800179c9SKees Cook 891800179c9SKees Cook /** 892800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 893800179c9SKees Cook * @inode: the source inode to hardlink from 894800179c9SKees Cook * 895800179c9SKees Cook * Return false if at least one of the following conditions: 896800179c9SKees Cook * - inode is not a regular file 897800179c9SKees Cook * - inode is setuid 898800179c9SKees Cook * - inode is setgid and group-exec 899800179c9SKees Cook * - access failure for read and write 900800179c9SKees Cook * 901800179c9SKees Cook * Otherwise returns true. 902800179c9SKees Cook */ 903800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 904800179c9SKees Cook { 905800179c9SKees Cook umode_t mode = inode->i_mode; 906800179c9SKees Cook 907800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 908800179c9SKees Cook if (!S_ISREG(mode)) 909800179c9SKees Cook return false; 910800179c9SKees Cook 911800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 912800179c9SKees Cook if (mode & S_ISUID) 913800179c9SKees Cook return false; 914800179c9SKees Cook 915800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 916800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 917800179c9SKees Cook return false; 918800179c9SKees Cook 919800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 920800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 921800179c9SKees Cook return false; 922800179c9SKees Cook 923800179c9SKees Cook return true; 924800179c9SKees Cook } 925800179c9SKees Cook 926800179c9SKees Cook /** 927800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 928800179c9SKees Cook * @link: the source to hardlink from 929800179c9SKees Cook * 930800179c9SKees Cook * Block hardlink when all of: 931800179c9SKees Cook * - sysctl_protected_hardlinks enabled 932800179c9SKees Cook * - fsuid does not match inode 933800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 934800179c9SKees Cook * - not CAP_FOWNER 935800179c9SKees Cook * 936800179c9SKees Cook * Returns 0 if successful, -ve on error. 937800179c9SKees Cook */ 938800179c9SKees Cook static int may_linkat(struct path *link) 939800179c9SKees Cook { 940800179c9SKees Cook const struct cred *cred; 941800179c9SKees Cook struct inode *inode; 942800179c9SKees Cook 943800179c9SKees Cook if (!sysctl_protected_hardlinks) 944800179c9SKees Cook return 0; 945800179c9SKees Cook 946800179c9SKees Cook cred = current_cred(); 947800179c9SKees Cook inode = link->dentry->d_inode; 948800179c9SKees Cook 949800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 950800179c9SKees Cook * otherwise, it must be a safe source. 951800179c9SKees Cook */ 95281abe27bSEric W. Biederman if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || 953800179c9SKees Cook capable(CAP_FOWNER)) 954800179c9SKees Cook return 0; 955800179c9SKees Cook 956a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 957800179c9SKees Cook return -EPERM; 958800179c9SKees Cook } 959800179c9SKees Cook 9603b2e7f75SAl Viro static __always_inline 9613b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 9621da177e4SLinus Torvalds { 963ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 9641cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 965237d8b32SAl Viro struct inode *inode = last->inode; 9666d7b5aaeSAl Viro int error; 9670a959df5SAl Viro const char *res; 9681da177e4SLinus Torvalds 969bc40aee0SAl Viro if (nd->flags & LOOKUP_RCU) { 970bc40aee0SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 971bc40aee0SAl Viro return ERR_PTR(-ECHILD); 972bc40aee0SAl Viro } 973574197e0SAl Viro cond_resched(); 974574197e0SAl Viro 9753b2e7f75SAl Viro touch_atime(&last->link); 976cd4e91d3SAl Viro 977bda0be7aSNeilBrown error = security_inode_follow_link(dentry, inode, 978bda0be7aSNeilBrown nd->flags & LOOKUP_RCU); 979bda0be7aSNeilBrown if (unlikely(error)) 9806920a440SAl Viro return ERR_PTR(error); 98136f3b4f6SAl Viro 98286acdca1SAl Viro nd->last_type = LAST_BIND; 983d4dee48bSAl Viro res = inode->i_link; 984d4dee48bSAl Viro if (!res) { 9856e77137bSAl Viro res = inode->i_op->follow_link(dentry, &last->cookie); 986fab51e8aSAl Viro if (IS_ERR_OR_NULL(res)) { 9876920a440SAl Viro last->cookie = NULL; 988fab51e8aSAl Viro return res; 9890a959df5SAl Viro } 990fab51e8aSAl Viro } 991fab51e8aSAl Viro if (*res == '/') { 992fab51e8aSAl Viro if (!nd->root.mnt) 993fab51e8aSAl Viro set_root(nd); 994fab51e8aSAl Viro path_put(&nd->path); 995fab51e8aSAl Viro nd->path = nd->root; 996fab51e8aSAl Viro path_get(&nd->root); 997fab51e8aSAl Viro nd->inode = nd->path.dentry->d_inode; 998fab51e8aSAl Viro nd->flags |= LOOKUP_JUMPED; 999fab51e8aSAl Viro while (unlikely(*++res == '/')) 1000fab51e8aSAl Viro ; 1001fab51e8aSAl Viro } 1002fab51e8aSAl Viro if (!*res) 1003fab51e8aSAl Viro res = NULL; 10040a959df5SAl Viro return res; 10050a959df5SAl Viro } 10066d7b5aaeSAl Viro 100731e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 100831e6b01fSNick Piggin { 10090714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 10100714a533SAl Viro struct mount *parent; 101131e6b01fSNick Piggin struct dentry *mountpoint; 101231e6b01fSNick Piggin 10130714a533SAl Viro parent = mnt->mnt_parent; 10140714a533SAl Viro if (&parent->mnt == path->mnt) 101531e6b01fSNick Piggin return 0; 1016a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 101731e6b01fSNick Piggin path->dentry = mountpoint; 10180714a533SAl Viro path->mnt = &parent->mnt; 101931e6b01fSNick Piggin return 1; 102031e6b01fSNick Piggin } 102131e6b01fSNick Piggin 1022f015f126SDavid Howells /* 1023f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1024f015f126SDavid Howells * 1025f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1026f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1027f015f126SDavid Howells * Up is towards /. 1028f015f126SDavid Howells * 1029f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1030f015f126SDavid Howells * root. 1031f015f126SDavid Howells */ 1032bab77ebfSAl Viro int follow_up(struct path *path) 10331da177e4SLinus Torvalds { 10340714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 10350714a533SAl Viro struct mount *parent; 10361da177e4SLinus Torvalds struct dentry *mountpoint; 103799b7db7bSNick Piggin 103848a066e7SAl Viro read_seqlock_excl(&mount_lock); 10390714a533SAl Viro parent = mnt->mnt_parent; 10403c0a6163SAl Viro if (parent == mnt) { 104148a066e7SAl Viro read_sequnlock_excl(&mount_lock); 10421da177e4SLinus Torvalds return 0; 10431da177e4SLinus Torvalds } 10440714a533SAl Viro mntget(&parent->mnt); 1045a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 104648a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1047bab77ebfSAl Viro dput(path->dentry); 1048bab77ebfSAl Viro path->dentry = mountpoint; 1049bab77ebfSAl Viro mntput(path->mnt); 10500714a533SAl Viro path->mnt = &parent->mnt; 10511da177e4SLinus Torvalds return 1; 10521da177e4SLinus Torvalds } 10534d359507SAl Viro EXPORT_SYMBOL(follow_up); 10541da177e4SLinus Torvalds 1055b5c84bf6SNick Piggin /* 10569875cf80SDavid Howells * Perform an automount 10579875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 10589875cf80SDavid Howells * were called with. 10591da177e4SLinus Torvalds */ 1060756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 10619875cf80SDavid Howells bool *need_mntput) 106231e6b01fSNick Piggin { 10639875cf80SDavid Howells struct vfsmount *mnt; 1064ea5b778aSDavid Howells int err; 10659875cf80SDavid Howells 10669875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 10679875cf80SDavid Howells return -EREMOTE; 10689875cf80SDavid Howells 10690ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 10700ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 10710ec26fd0SMiklos Szeredi * the name. 10720ec26fd0SMiklos Szeredi * 10730ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 10745a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 10750ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 10760ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 10770ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 10780ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 10795a30d8a2SDavid Howells */ 1080756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 1081d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 10825a30d8a2SDavid Howells path->dentry->d_inode) 10839875cf80SDavid Howells return -EISDIR; 10840ec26fd0SMiklos Szeredi 1085756daf26SNeilBrown nd->total_link_count++; 1086756daf26SNeilBrown if (nd->total_link_count >= 40) 10879875cf80SDavid Howells return -ELOOP; 10889875cf80SDavid Howells 10899875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 10909875cf80SDavid Howells if (IS_ERR(mnt)) { 10919875cf80SDavid Howells /* 10929875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 10939875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 10949875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 10959875cf80SDavid Howells * 10969875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 10979875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 10989875cf80SDavid Howells * the path is inaccessible and we should say so. 10999875cf80SDavid Howells */ 1100756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 11019875cf80SDavid Howells return -EREMOTE; 11029875cf80SDavid Howells return PTR_ERR(mnt); 110331e6b01fSNick Piggin } 1104ea5b778aSDavid Howells 11059875cf80SDavid Howells if (!mnt) /* mount collision */ 11069875cf80SDavid Howells return 0; 11079875cf80SDavid Howells 11088aef1884SAl Viro if (!*need_mntput) { 11098aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 11108aef1884SAl Viro mntget(path->mnt); 11118aef1884SAl Viro *need_mntput = true; 11128aef1884SAl Viro } 111319a167afSAl Viro err = finish_automount(mnt, path); 1114ea5b778aSDavid Howells 1115ea5b778aSDavid Howells switch (err) { 1116ea5b778aSDavid Howells case -EBUSY: 1117ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 111819a167afSAl Viro return 0; 1119ea5b778aSDavid Howells case 0: 11208aef1884SAl Viro path_put(path); 11219875cf80SDavid Howells path->mnt = mnt; 11229875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 11239875cf80SDavid Howells return 0; 112419a167afSAl Viro default: 112519a167afSAl Viro return err; 11269875cf80SDavid Howells } 112719a167afSAl Viro 1128ea5b778aSDavid Howells } 11299875cf80SDavid Howells 11309875cf80SDavid Howells /* 11319875cf80SDavid Howells * Handle a dentry that is managed in some way. 1132cc53ce53SDavid Howells * - Flagged for transit management (autofs) 11339875cf80SDavid Howells * - Flagged as mountpoint 11349875cf80SDavid Howells * - Flagged as automount point 11359875cf80SDavid Howells * 11369875cf80SDavid Howells * This may only be called in refwalk mode. 11379875cf80SDavid Howells * 11389875cf80SDavid Howells * Serialization is taken care of in namespace.c 11399875cf80SDavid Howells */ 1140756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 11419875cf80SDavid Howells { 11428aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 11439875cf80SDavid Howells unsigned managed; 11449875cf80SDavid Howells bool need_mntput = false; 11458aef1884SAl Viro int ret = 0; 11469875cf80SDavid Howells 11479875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 11489875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 11499875cf80SDavid Howells * the components of that value change under us */ 11509875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 11519875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 11529875cf80SDavid Howells unlikely(managed != 0)) { 1153cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1154cc53ce53SDavid Howells * being held. */ 1155cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1156cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1157cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 11581aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1159cc53ce53SDavid Howells if (ret < 0) 11608aef1884SAl Viro break; 1161cc53ce53SDavid Howells } 1162cc53ce53SDavid Howells 11639875cf80SDavid Howells /* Transit to a mounted filesystem. */ 11649875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 11659875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 11669875cf80SDavid Howells if (mounted) { 11679875cf80SDavid Howells dput(path->dentry); 11689875cf80SDavid Howells if (need_mntput) 1169463ffb2eSAl Viro mntput(path->mnt); 1170463ffb2eSAl Viro path->mnt = mounted; 1171463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 11729875cf80SDavid Howells need_mntput = true; 11739875cf80SDavid Howells continue; 1174463ffb2eSAl Viro } 1175463ffb2eSAl Viro 11769875cf80SDavid Howells /* Something is mounted on this dentry in another 11779875cf80SDavid Howells * namespace and/or whatever was mounted there in this 117848a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 117948a066e7SAl Viro * get it */ 11801da177e4SLinus Torvalds } 11819875cf80SDavid Howells 11829875cf80SDavid Howells /* Handle an automount point */ 11839875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1184756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 11859875cf80SDavid Howells if (ret < 0) 11868aef1884SAl Viro break; 11879875cf80SDavid Howells continue; 11889875cf80SDavid Howells } 11899875cf80SDavid Howells 11909875cf80SDavid Howells /* We didn't change the current path point */ 11919875cf80SDavid Howells break; 11929875cf80SDavid Howells } 11938aef1884SAl Viro 11948aef1884SAl Viro if (need_mntput && path->mnt == mnt) 11958aef1884SAl Viro mntput(path->mnt); 11968aef1884SAl Viro if (ret == -EISDIR) 11978aef1884SAl Viro ret = 0; 11988402752eSAl Viro if (need_mntput) 11998402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 12008402752eSAl Viro if (unlikely(ret < 0)) 12018402752eSAl Viro path_put_conditional(path, nd); 12028402752eSAl Viro return ret; 12031da177e4SLinus Torvalds } 12041da177e4SLinus Torvalds 1205cc53ce53SDavid Howells int follow_down_one(struct path *path) 12061da177e4SLinus Torvalds { 12071da177e4SLinus Torvalds struct vfsmount *mounted; 12081da177e4SLinus Torvalds 12091c755af4SAl Viro mounted = lookup_mnt(path); 12101da177e4SLinus Torvalds if (mounted) { 12119393bd07SAl Viro dput(path->dentry); 12129393bd07SAl Viro mntput(path->mnt); 12139393bd07SAl Viro path->mnt = mounted; 12149393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12151da177e4SLinus Torvalds return 1; 12161da177e4SLinus Torvalds } 12171da177e4SLinus Torvalds return 0; 12181da177e4SLinus Torvalds } 12194d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12201da177e4SLinus Torvalds 1221b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 122262a7375eSIan Kent { 1223b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1224b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 122562a7375eSIan Kent } 122662a7375eSIan Kent 12279875cf80SDavid Howells /* 1228287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1229287548e4SAl Viro * we meet a managed dentry that would need blocking. 12309875cf80SDavid Howells */ 12319875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1232254cf582SAl Viro struct inode **inode, unsigned *seqp) 12339875cf80SDavid Howells { 123462a7375eSIan Kent for (;;) { 1235c7105365SAl Viro struct mount *mounted; 123662a7375eSIan Kent /* 123762a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 123862a7375eSIan Kent * that wants to block transit. 123962a7375eSIan Kent */ 1240b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1241b8faf035SNeilBrown case -ECHILD: 1242b8faf035SNeilBrown default: 1243ab90911fSDavid Howells return false; 1244b8faf035SNeilBrown case -EISDIR: 1245b8faf035SNeilBrown return true; 1246b8faf035SNeilBrown case 0: 1247b8faf035SNeilBrown break; 1248b8faf035SNeilBrown } 124962a7375eSIan Kent 125062a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1251b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 125262a7375eSIan Kent 1253474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 12549875cf80SDavid Howells if (!mounted) 12559875cf80SDavid Howells break; 1256c7105365SAl Viro path->mnt = &mounted->mnt; 1257c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1258a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1259254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 126059430262SLinus Torvalds /* 126159430262SLinus Torvalds * Update the inode too. We don't need to re-check the 126259430262SLinus Torvalds * dentry sequence number here after this d_inode read, 126359430262SLinus Torvalds * because a mount-point is always pinned. 126459430262SLinus Torvalds */ 126559430262SLinus Torvalds *inode = path->dentry->d_inode; 12669875cf80SDavid Howells } 1267f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1268b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1269287548e4SAl Viro } 1270287548e4SAl Viro 127131e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 127231e6b01fSNick Piggin { 12734023bfc9SAl Viro struct inode *inode = nd->inode; 12747bd88377SAl Viro if (!nd->root.mnt) 127531e6b01fSNick Piggin set_root_rcu(nd); 127631e6b01fSNick Piggin 127731e6b01fSNick Piggin while (1) { 127831e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 127931e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 128031e6b01fSNick Piggin break; 128131e6b01fSNick Piggin } 128231e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 128331e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 128431e6b01fSNick Piggin struct dentry *parent = old->d_parent; 128531e6b01fSNick Piggin unsigned seq; 128631e6b01fSNick Piggin 12874023bfc9SAl Viro inode = parent->d_inode; 128831e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 128931e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1290ef7562d5SAl Viro goto failed; 129131e6b01fSNick Piggin nd->path.dentry = parent; 129231e6b01fSNick Piggin nd->seq = seq; 129331e6b01fSNick Piggin break; 129431e6b01fSNick Piggin } 129531e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 129631e6b01fSNick Piggin break; 12974023bfc9SAl Viro inode = nd->path.dentry->d_inode; 129831e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 129931e6b01fSNick Piggin } 1300b37199e6SAl Viro while (d_mountpoint(nd->path.dentry)) { 1301b37199e6SAl Viro struct mount *mounted; 1302b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1303b37199e6SAl Viro if (!mounted) 1304b37199e6SAl Viro break; 1305b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1306b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 13074023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1308b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1309f5be3e29SAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1310b37199e6SAl Viro goto failed; 1311b37199e6SAl Viro } 13124023bfc9SAl Viro nd->inode = inode; 131331e6b01fSNick Piggin return 0; 1314ef7562d5SAl Viro 1315ef7562d5SAl Viro failed: 1316ef7562d5SAl Viro return -ECHILD; 131731e6b01fSNick Piggin } 131831e6b01fSNick Piggin 13199875cf80SDavid Howells /* 1320cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1321cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1322cc53ce53SDavid Howells * caller is permitted to proceed or not. 1323cc53ce53SDavid Howells */ 13247cc90cc3SAl Viro int follow_down(struct path *path) 1325cc53ce53SDavid Howells { 1326cc53ce53SDavid Howells unsigned managed; 1327cc53ce53SDavid Howells int ret; 1328cc53ce53SDavid Howells 1329cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1330cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1331cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1332cc53ce53SDavid Howells * being held. 1333cc53ce53SDavid Howells * 1334cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1335cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1336cc53ce53SDavid Howells * other than its daemon the right to mount on its 1337cc53ce53SDavid Howells * superstructure. 1338cc53ce53SDavid Howells * 1339cc53ce53SDavid Howells * The filesystem may sleep at this point. 1340cc53ce53SDavid Howells */ 1341cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1342cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1343cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1344ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 13451aed3e42SAl Viro path->dentry, false); 1346cc53ce53SDavid Howells if (ret < 0) 1347cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1348cc53ce53SDavid Howells } 1349cc53ce53SDavid Howells 1350cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1351cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1352cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1353cc53ce53SDavid Howells if (!mounted) 1354cc53ce53SDavid Howells break; 1355cc53ce53SDavid Howells dput(path->dentry); 1356cc53ce53SDavid Howells mntput(path->mnt); 1357cc53ce53SDavid Howells path->mnt = mounted; 1358cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1359cc53ce53SDavid Howells continue; 1360cc53ce53SDavid Howells } 1361cc53ce53SDavid Howells 1362cc53ce53SDavid Howells /* Don't handle automount points here */ 1363cc53ce53SDavid Howells break; 1364cc53ce53SDavid Howells } 1365cc53ce53SDavid Howells return 0; 1366cc53ce53SDavid Howells } 13674d359507SAl Viro EXPORT_SYMBOL(follow_down); 1368cc53ce53SDavid Howells 1369cc53ce53SDavid Howells /* 13709875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 13719875cf80SDavid Howells */ 13729875cf80SDavid Howells static void follow_mount(struct path *path) 13739875cf80SDavid Howells { 13749875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 13759875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 13769875cf80SDavid Howells if (!mounted) 13779875cf80SDavid Howells break; 13789875cf80SDavid Howells dput(path->dentry); 13799875cf80SDavid Howells mntput(path->mnt); 13809875cf80SDavid Howells path->mnt = mounted; 13819875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 13829875cf80SDavid Howells } 13839875cf80SDavid Howells } 13849875cf80SDavid Howells 138531e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 13861da177e4SLinus Torvalds { 13877bd88377SAl Viro if (!nd->root.mnt) 13882a737871SAl Viro set_root(nd); 1389e518ddb7SAndreas Mohr 13901da177e4SLinus Torvalds while(1) { 13914ac91378SJan Blunck struct dentry *old = nd->path.dentry; 13921da177e4SLinus Torvalds 13932a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 13942a737871SAl Viro nd->path.mnt == nd->root.mnt) { 13951da177e4SLinus Torvalds break; 13961da177e4SLinus Torvalds } 13974ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 13983088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 13993088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 14001da177e4SLinus Torvalds dput(old); 14011da177e4SLinus Torvalds break; 14021da177e4SLinus Torvalds } 14033088dd70SAl Viro if (!follow_up(&nd->path)) 14041da177e4SLinus Torvalds break; 14051da177e4SLinus Torvalds } 140679ed0226SAl Viro follow_mount(&nd->path); 140731e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 14081da177e4SLinus Torvalds } 14091da177e4SLinus Torvalds 14101da177e4SLinus Torvalds /* 1411bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1412bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1413bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1414bad61189SMiklos Szeredi * 1415bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1416baa03890SNick Piggin */ 1417bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1418201f956eSAl Viro unsigned int flags, bool *need_lookup) 1419baa03890SNick Piggin { 1420baa03890SNick Piggin struct dentry *dentry; 1421bad61189SMiklos Szeredi int error; 1422baa03890SNick Piggin 1423bad61189SMiklos Szeredi *need_lookup = false; 1424bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1425bad61189SMiklos Szeredi if (dentry) { 142639e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1427201f956eSAl Viro error = d_revalidate(dentry, flags); 1428bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1429bad61189SMiklos Szeredi if (error < 0) { 1430bad61189SMiklos Szeredi dput(dentry); 1431bad61189SMiklos Szeredi return ERR_PTR(error); 14325542aa2fSEric W. Biederman } else { 14335542aa2fSEric W. Biederman d_invalidate(dentry); 1434bad61189SMiklos Szeredi dput(dentry); 1435bad61189SMiklos Szeredi dentry = NULL; 1436bad61189SMiklos Szeredi } 1437bad61189SMiklos Szeredi } 1438bad61189SMiklos Szeredi } 1439bad61189SMiklos Szeredi } 1440baa03890SNick Piggin 1441bad61189SMiklos Szeredi if (!dentry) { 1442bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1443baa03890SNick Piggin if (unlikely(!dentry)) 1444baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1445baa03890SNick Piggin 1446bad61189SMiklos Szeredi *need_lookup = true; 1447baa03890SNick Piggin } 1448baa03890SNick Piggin return dentry; 1449baa03890SNick Piggin } 1450baa03890SNick Piggin 1451baa03890SNick Piggin /* 145213a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 145313a2c3beSJ. Bruce Fields * unhashed. 1454bad61189SMiklos Szeredi * 1455bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 145644396f4bSJosef Bacik */ 1457bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 145872bd866aSAl Viro unsigned int flags) 145944396f4bSJosef Bacik { 146044396f4bSJosef Bacik struct dentry *old; 146144396f4bSJosef Bacik 146244396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1463bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1464e188dc02SMiklos Szeredi dput(dentry); 146544396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1466e188dc02SMiklos Szeredi } 146744396f4bSJosef Bacik 146872bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 146944396f4bSJosef Bacik if (unlikely(old)) { 147044396f4bSJosef Bacik dput(dentry); 147144396f4bSJosef Bacik dentry = old; 147244396f4bSJosef Bacik } 147344396f4bSJosef Bacik return dentry; 147444396f4bSJosef Bacik } 147544396f4bSJosef Bacik 1476a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 147772bd866aSAl Viro struct dentry *base, unsigned int flags) 1478a3255546SAl Viro { 1479bad61189SMiklos Szeredi bool need_lookup; 1480a3255546SAl Viro struct dentry *dentry; 1481a3255546SAl Viro 148272bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1483bad61189SMiklos Szeredi if (!need_lookup) 1484a3255546SAl Viro return dentry; 1485bad61189SMiklos Szeredi 148672bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1487a3255546SAl Viro } 1488a3255546SAl Viro 148944396f4bSJosef Bacik /* 14901da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 14911da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 14921da177e4SLinus Torvalds * It _is_ time-critical. 14931da177e4SLinus Torvalds */ 1494e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 1495254cf582SAl Viro struct path *path, struct inode **inode, 1496254cf582SAl Viro unsigned *seqp) 14971da177e4SLinus Torvalds { 14984ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 149931e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 15005a18fff2SAl Viro int need_reval = 1; 15015a18fff2SAl Viro int status = 1; 15029875cf80SDavid Howells int err; 15039875cf80SDavid Howells 15043cac260aSAl Viro /* 1505b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1506b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1507b04f784eSNick Piggin * do the non-racy lookup, below. 1508b04f784eSNick Piggin */ 150931e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 151031e6b01fSNick Piggin unsigned seq; 1511766c4cbfSAl Viro bool negative; 1512da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15135a18fff2SAl Viro if (!dentry) 15145a18fff2SAl Viro goto unlazy; 15155a18fff2SAl Viro 151612f8ad4bSLinus Torvalds /* 151712f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 151812f8ad4bSLinus Torvalds * the dentry name information from lookup. 151912f8ad4bSLinus Torvalds */ 152063afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1521766c4cbfSAl Viro negative = d_is_negative(dentry); 152212f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 152312f8ad4bSLinus Torvalds return -ECHILD; 1524766c4cbfSAl Viro if (negative) 1525766c4cbfSAl Viro return -ENOENT; 152612f8ad4bSLinus Torvalds 152712f8ad4bSLinus Torvalds /* 152812f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 152912f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 153012f8ad4bSLinus Torvalds * 153112f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 153212f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 153312f8ad4bSLinus Torvalds */ 153431e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 153531e6b01fSNick Piggin return -ECHILD; 15365a18fff2SAl Viro 1537254cf582SAl Viro *seqp = seq; 153824643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 15394ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15405a18fff2SAl Viro if (unlikely(status <= 0)) { 15415a18fff2SAl Viro if (status != -ECHILD) 15425a18fff2SAl Viro need_reval = 0; 15435a18fff2SAl Viro goto unlazy; 15445a18fff2SAl Viro } 154524643087SAl Viro } 154631e6b01fSNick Piggin path->mnt = mnt; 154731e6b01fSNick Piggin path->dentry = dentry; 1548254cf582SAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 15499875cf80SDavid Howells return 0; 15505a18fff2SAl Viro unlazy: 1551254cf582SAl Viro if (unlazy_walk(nd, dentry, seq)) 15525a18fff2SAl Viro return -ECHILD; 15535a18fff2SAl Viro } else { 1554e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 155524643087SAl Viro } 15565a18fff2SAl Viro 155781e6f520SAl Viro if (unlikely(!dentry)) 155881e6f520SAl Viro goto need_lookup; 15595a18fff2SAl Viro 15605a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 15614ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15625a18fff2SAl Viro if (unlikely(status <= 0)) { 15635a18fff2SAl Viro if (status < 0) { 15645a18fff2SAl Viro dput(dentry); 15655a18fff2SAl Viro return status; 15665a18fff2SAl Viro } 15675542aa2fSEric W. Biederman d_invalidate(dentry); 15685a18fff2SAl Viro dput(dentry); 156981e6f520SAl Viro goto need_lookup; 15705a18fff2SAl Viro } 1571697f514dSMiklos Szeredi 1572766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1573766c4cbfSAl Viro dput(dentry); 1574766c4cbfSAl Viro return -ENOENT; 1575766c4cbfSAl Viro } 15761da177e4SLinus Torvalds path->mnt = mnt; 15771da177e4SLinus Torvalds path->dentry = dentry; 1578756daf26SNeilBrown err = follow_managed(path, nd); 15798402752eSAl Viro if (likely(!err)) 158063afdfc7SDavid Howells *inode = d_backing_inode(path->dentry); 15818402752eSAl Viro return err; 158281e6f520SAl Viro 158381e6f520SAl Viro need_lookup: 1584697f514dSMiklos Szeredi return 1; 1585697f514dSMiklos Szeredi } 1586697f514dSMiklos Szeredi 1587697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1588cc2a5271SAl Viro static int lookup_slow(struct nameidata *nd, struct path *path) 1589697f514dSMiklos Szeredi { 1590697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1591697f514dSMiklos Szeredi 1592697f514dSMiklos Szeredi parent = nd->path.dentry; 159381e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 159481e6f520SAl Viro 159581e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 1596cc2a5271SAl Viro dentry = __lookup_hash(&nd->last, parent, nd->flags); 159781e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 159881e6f520SAl Viro if (IS_ERR(dentry)) 159981e6f520SAl Viro return PTR_ERR(dentry); 1600697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1601697f514dSMiklos Szeredi path->dentry = dentry; 16028402752eSAl Viro return follow_managed(path, nd); 16031da177e4SLinus Torvalds } 16041da177e4SLinus Torvalds 160552094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 160652094c8aSAl Viro { 160752094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16084ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 160952094c8aSAl Viro if (err != -ECHILD) 161052094c8aSAl Viro return err; 16116e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 161252094c8aSAl Viro return -ECHILD; 161352094c8aSAl Viro } 16144ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 161552094c8aSAl Viro } 161652094c8aSAl Viro 16179856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 16189856fa1bSAl Viro { 16199856fa1bSAl Viro if (type == LAST_DOTDOT) { 16209856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 162170291aecSAl Viro return follow_dotdot_rcu(nd); 16229856fa1bSAl Viro } else 16239856fa1bSAl Viro follow_dotdot(nd); 16249856fa1bSAl Viro } 16259856fa1bSAl Viro return 0; 16269856fa1bSAl Viro } 16279856fa1bSAl Viro 1628181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1629181548c0SAl Viro struct inode *inode, unsigned seq) 1630d63ff28fSAl Viro { 1631626de996SAl Viro int error; 16321cf2665bSAl Viro struct saved *last; 1633756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1634626de996SAl Viro path_to_nameidata(link, nd); 1635626de996SAl Viro return -ELOOP; 1636626de996SAl Viro } 1637bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1638cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1639cd179f44SAl Viro mntget(link->mnt); 16407973387aSAl Viro } 1641626de996SAl Viro error = nd_alloc_stack(nd); 1642626de996SAl Viro if (unlikely(error)) { 1643bc40aee0SAl Viro if (error == -ECHILD) { 1644bc40aee0SAl Viro if (unlikely(unlazy_link(nd, link, seq))) 1645bc40aee0SAl Viro return -ECHILD; 1646bc40aee0SAl Viro error = nd_alloc_stack(nd); 1647bc40aee0SAl Viro } 1648bc40aee0SAl Viro if (error) { 1649cd179f44SAl Viro path_put(link); 1650626de996SAl Viro return error; 1651626de996SAl Viro } 1652bc40aee0SAl Viro } 1653626de996SAl Viro 1654ab104923SAl Viro last = nd->stack + nd->depth++; 16551cf2665bSAl Viro last->link = *link; 1656ab104923SAl Viro last->cookie = NULL; 1657181548c0SAl Viro last->inode = inode; 16580450b2d1SAl Viro last->seq = seq; 1659d63ff28fSAl Viro return 1; 1660d63ff28fSAl Viro } 1661d63ff28fSAl Viro 16623ddcd056SLinus Torvalds /* 16633ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 16643ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 16653ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 16663ddcd056SLinus Torvalds * for the common case. 16673ddcd056SLinus Torvalds */ 1668254cf582SAl Viro static inline int should_follow_link(struct nameidata *nd, struct path *link, 1669181548c0SAl Viro int follow, 1670181548c0SAl Viro struct inode *inode, unsigned seq) 16713ddcd056SLinus Torvalds { 1672d63ff28fSAl Viro if (likely(!d_is_symlink(link->dentry))) 1673d63ff28fSAl Viro return 0; 1674d63ff28fSAl Viro if (!follow) 1675d63ff28fSAl Viro return 0; 1676181548c0SAl Viro return pick_link(nd, link, inode, seq); 16773ddcd056SLinus Torvalds } 16783ddcd056SLinus Torvalds 16794693a547SAl Viro enum {WALK_GET = 1, WALK_PUT = 2}; 16804693a547SAl Viro 16814693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1682ce57dfc1SAl Viro { 1683caa85634SAl Viro struct path path; 1684ce57dfc1SAl Viro struct inode *inode; 1685254cf582SAl Viro unsigned seq; 1686ce57dfc1SAl Viro int err; 1687ce57dfc1SAl Viro /* 1688ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1689ce57dfc1SAl Viro * to be able to know about the current root directory and 1690ce57dfc1SAl Viro * parent relationships. 1691ce57dfc1SAl Viro */ 16924693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 16934693a547SAl Viro err = handle_dots(nd, nd->last_type); 16944693a547SAl Viro if (flags & WALK_PUT) 16954693a547SAl Viro put_link(nd); 16964693a547SAl Viro return err; 16974693a547SAl Viro } 1698254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1699ce57dfc1SAl Viro if (unlikely(err)) { 1700697f514dSMiklos Szeredi if (err < 0) 1701f0a9ba70SAl Viro return err; 1702697f514dSMiklos Szeredi 1703caa85634SAl Viro err = lookup_slow(nd, &path); 1704697f514dSMiklos Szeredi if (err < 0) 1705f0a9ba70SAl Viro return err; 1706697f514dSMiklos Szeredi 170763afdfc7SDavid Howells inode = d_backing_inode(path.dentry); 1708254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1709697f514dSMiklos Szeredi err = -ENOENT; 1710caa85634SAl Viro if (d_is_negative(path.dentry)) 1711697f514dSMiklos Szeredi goto out_path_put; 1712766c4cbfSAl Viro } 1713697f514dSMiklos Szeredi 17144693a547SAl Viro if (flags & WALK_PUT) 17154693a547SAl Viro put_link(nd); 1716181548c0SAl Viro err = should_follow_link(nd, &path, flags & WALK_GET, inode, seq); 1717d63ff28fSAl Viro if (unlikely(err)) 1718d63ff28fSAl Viro return err; 1719caa85634SAl Viro path_to_nameidata(&path, nd); 1720ce57dfc1SAl Viro nd->inode = inode; 1721254cf582SAl Viro nd->seq = seq; 1722ce57dfc1SAl Viro return 0; 1723697f514dSMiklos Szeredi 1724697f514dSMiklos Szeredi out_path_put: 1725caa85634SAl Viro path_to_nameidata(&path, nd); 1726697f514dSMiklos Szeredi return err; 1727ce57dfc1SAl Viro } 1728ce57dfc1SAl Viro 17291da177e4SLinus Torvalds /* 1730bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1731bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1732bfcfaa77SLinus Torvalds * 1733bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1734bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1735bfcfaa77SLinus Torvalds * fast. 1736bfcfaa77SLinus Torvalds * 1737bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1738bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1739bfcfaa77SLinus Torvalds * crossing operation. 1740bfcfaa77SLinus Torvalds * 1741bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1742bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1743bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1744bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1745bfcfaa77SLinus Torvalds */ 1746bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1747bfcfaa77SLinus Torvalds 1748f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1749bfcfaa77SLinus Torvalds 1750f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1751bfcfaa77SLinus Torvalds 1752bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1753bfcfaa77SLinus Torvalds { 175499d263d4SLinus Torvalds return hash_64(hash, 32); 1755bfcfaa77SLinus Torvalds } 1756bfcfaa77SLinus Torvalds 1757bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1758bfcfaa77SLinus Torvalds 1759bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1760bfcfaa77SLinus Torvalds 1761bfcfaa77SLinus Torvalds #endif 1762bfcfaa77SLinus Torvalds 1763bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1764bfcfaa77SLinus Torvalds { 1765bfcfaa77SLinus Torvalds unsigned long a, mask; 1766bfcfaa77SLinus Torvalds unsigned long hash = 0; 1767bfcfaa77SLinus Torvalds 1768bfcfaa77SLinus Torvalds for (;;) { 1769e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1770bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1771bfcfaa77SLinus Torvalds break; 1772bfcfaa77SLinus Torvalds hash += a; 1773f132c5beSAl Viro hash *= 9; 1774bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1775bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1776bfcfaa77SLinus Torvalds if (!len) 1777bfcfaa77SLinus Torvalds goto done; 1778bfcfaa77SLinus Torvalds } 1779a5c21dceSWill Deacon mask = bytemask_from_count(len); 1780bfcfaa77SLinus Torvalds hash += mask & a; 1781bfcfaa77SLinus Torvalds done: 1782bfcfaa77SLinus Torvalds return fold_hash(hash); 1783bfcfaa77SLinus Torvalds } 1784bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1785bfcfaa77SLinus Torvalds 1786bfcfaa77SLinus Torvalds /* 1787bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1788d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1789bfcfaa77SLinus Torvalds */ 1790d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1791bfcfaa77SLinus Torvalds { 179236126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 179336126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1794bfcfaa77SLinus Torvalds 1795bfcfaa77SLinus Torvalds hash = a = 0; 1796bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1797bfcfaa77SLinus Torvalds do { 1798bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1799bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1800e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 180136126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 180236126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1803bfcfaa77SLinus Torvalds 180436126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 180536126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 180636126f8fSLinus Torvalds 180736126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 180836126f8fSLinus Torvalds 180936126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 18109226b5b4SLinus Torvalds len += find_zero(mask); 1811d6bb3e90SLinus Torvalds return hashlen_create(fold_hash(hash), len); 1812bfcfaa77SLinus Torvalds } 1813bfcfaa77SLinus Torvalds 1814bfcfaa77SLinus Torvalds #else 1815bfcfaa77SLinus Torvalds 18160145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 18170145acc2SLinus Torvalds { 18180145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 18190145acc2SLinus Torvalds while (len--) 18200145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 18210145acc2SLinus Torvalds return end_name_hash(hash); 18220145acc2SLinus Torvalds } 1823ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 18240145acc2SLinus Torvalds 18253ddcd056SLinus Torvalds /* 1826200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1827200e9ef7SLinus Torvalds * one character. 1828200e9ef7SLinus Torvalds */ 1829d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1830200e9ef7SLinus Torvalds { 1831200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1832200e9ef7SLinus Torvalds unsigned long len = 0, c; 1833200e9ef7SLinus Torvalds 1834200e9ef7SLinus Torvalds c = (unsigned char)*name; 1835200e9ef7SLinus Torvalds do { 1836200e9ef7SLinus Torvalds len++; 1837200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1838200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1839200e9ef7SLinus Torvalds } while (c && c != '/'); 1840d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 1841200e9ef7SLinus Torvalds } 1842200e9ef7SLinus Torvalds 1843bfcfaa77SLinus Torvalds #endif 1844bfcfaa77SLinus Torvalds 1845200e9ef7SLinus Torvalds /* 18461da177e4SLinus Torvalds * Name resolution. 1847ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1848ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 18491da177e4SLinus Torvalds * 1850ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1851ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 18521da177e4SLinus Torvalds */ 18536de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 18541da177e4SLinus Torvalds { 18551da177e4SLinus Torvalds int err; 18561da177e4SLinus Torvalds 18571da177e4SLinus Torvalds while (*name=='/') 18581da177e4SLinus Torvalds name++; 18591da177e4SLinus Torvalds if (!*name) 18609e18f10aSAl Viro return 0; 18611da177e4SLinus Torvalds 18621da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 18631da177e4SLinus Torvalds for(;;) { 1864d6bb3e90SLinus Torvalds u64 hash_len; 1865fe479a58SAl Viro int type; 18661da177e4SLinus Torvalds 186752094c8aSAl Viro err = may_lookup(nd); 18681da177e4SLinus Torvalds if (err) 18693595e234SAl Viro return err; 18701da177e4SLinus Torvalds 1871d6bb3e90SLinus Torvalds hash_len = hash_name(name); 18721da177e4SLinus Torvalds 1873fe479a58SAl Viro type = LAST_NORM; 1874d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 1875fe479a58SAl Viro case 2: 1876200e9ef7SLinus Torvalds if (name[1] == '.') { 1877fe479a58SAl Viro type = LAST_DOTDOT; 187816c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 187916c2cd71SAl Viro } 1880fe479a58SAl Viro break; 1881fe479a58SAl Viro case 1: 1882fe479a58SAl Viro type = LAST_DOT; 1883fe479a58SAl Viro } 18845a202bcdSAl Viro if (likely(type == LAST_NORM)) { 18855a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 188616c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 18875a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 1888a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 1889da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 18905a202bcdSAl Viro if (err < 0) 18913595e234SAl Viro return err; 1892d6bb3e90SLinus Torvalds hash_len = this.hash_len; 1893d6bb3e90SLinus Torvalds name = this.name; 18945a202bcdSAl Viro } 18955a202bcdSAl Viro } 1896fe479a58SAl Viro 1897d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 1898d6bb3e90SLinus Torvalds nd->last.name = name; 18995f4a6a69SAl Viro nd->last_type = type; 19005f4a6a69SAl Viro 1901d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 1902d6bb3e90SLinus Torvalds if (!*name) 1903bdf6cbf1SAl Viro goto OK; 1904200e9ef7SLinus Torvalds /* 1905200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1906200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1907200e9ef7SLinus Torvalds */ 1908200e9ef7SLinus Torvalds do { 1909d6bb3e90SLinus Torvalds name++; 1910d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 19118620c238SAl Viro if (unlikely(!*name)) { 19128620c238SAl Viro OK: 1913368ee9baSAl Viro /* pathname body, done */ 19148620c238SAl Viro if (!nd->depth) 19158620c238SAl Viro return 0; 19168620c238SAl Viro name = nd->stack[nd->depth - 1].name; 1917368ee9baSAl Viro /* trailing symlink, done */ 19188620c238SAl Viro if (!name) 19198620c238SAl Viro return 0; 19208620c238SAl Viro /* last component of nested symlink */ 19214693a547SAl Viro err = walk_component(nd, WALK_GET | WALK_PUT); 19228620c238SAl Viro } else { 19234693a547SAl Viro err = walk_component(nd, WALK_GET); 19248620c238SAl Viro } 1925ce57dfc1SAl Viro if (err < 0) 19263595e234SAl Viro return err; 1927fe479a58SAl Viro 1928ce57dfc1SAl Viro if (err) { 1929626de996SAl Viro const char *s = get_link(nd); 19305a460275SAl Viro 19313595e234SAl Viro if (unlikely(IS_ERR(s))) 19323595e234SAl Viro return PTR_ERR(s); 1933172a39a0SAl Viro err = 0; 193412b09578SAl Viro if (unlikely(!s)) { 193512b09578SAl Viro /* jumped */ 1936b9ff4429SAl Viro put_link(nd); 193712b09578SAl Viro } else { 1938071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 193932cd7468SAl Viro name = s; 19409e18f10aSAl Viro continue; 194148c8b0c5SAl Viro } 194231e6b01fSNick Piggin } 19433595e234SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) 19443595e234SAl Viro return -ENOTDIR; 19455f4a6a69SAl Viro } 1946ce57dfc1SAl Viro } 19471da177e4SLinus Torvalds 1948368ee9baSAl Viro static const char *path_init(int dfd, const struct filename *name, 1949368ee9baSAl Viro unsigned int flags, struct nameidata *nd) 195031e6b01fSNick Piggin { 195131e6b01fSNick Piggin int retval = 0; 1952fd2f7cb5SAl Viro const char *s = name->name; 195331e6b01fSNick Piggin 195431e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 1955980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 195631e6b01fSNick Piggin nd->depth = 0; 1957368ee9baSAl Viro nd->total_link_count = 0; 19585b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 1959b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 1960b18825a7SDavid Howells struct inode *inode = root->d_inode; 1961fd2f7cb5SAl Viro if (*s) { 196244b1d530SMiklos Szeredi if (!d_can_lookup(root)) 1963368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 19645b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 19655b6ca027SAl Viro if (retval) 1966368ee9baSAl Viro return ERR_PTR(retval); 196773d049a4SAl Viro } 19685b6ca027SAl Viro nd->path = nd->root; 19695b6ca027SAl Viro nd->inode = inode; 19705b6ca027SAl Viro if (flags & LOOKUP_RCU) { 19718b61e74fSAl Viro rcu_read_lock(); 19725b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 197348a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 19745b6ca027SAl Viro } else { 19755b6ca027SAl Viro path_get(&nd->path); 19765b6ca027SAl Viro } 1977368ee9baSAl Viro return s; 19785b6ca027SAl Viro } 19795b6ca027SAl Viro 198031e6b01fSNick Piggin nd->root.mnt = NULL; 198131e6b01fSNick Piggin 198248a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 1983fd2f7cb5SAl Viro if (*s == '/') { 1984e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 19858b61e74fSAl Viro rcu_read_lock(); 19867bd88377SAl Viro nd->seq = set_root_rcu(nd); 1987e41f7d4eSAl Viro } else { 1988e41f7d4eSAl Viro set_root(nd); 1989e41f7d4eSAl Viro path_get(&nd->root); 1990e41f7d4eSAl Viro } 199131e6b01fSNick Piggin nd->path = nd->root; 199231e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1993e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 199431e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1995c28cc364SNick Piggin unsigned seq; 199631e6b01fSNick Piggin 19978b61e74fSAl Viro rcu_read_lock(); 199831e6b01fSNick Piggin 1999c28cc364SNick Piggin do { 2000c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 200131e6b01fSNick Piggin nd->path = fs->pwd; 2002c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2003c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2004e41f7d4eSAl Viro } else { 2005e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2006e41f7d4eSAl Viro } 200731e6b01fSNick Piggin } else { 2008582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 20092903ff01SAl Viro struct fd f = fdget_raw(dfd); 201031e6b01fSNick Piggin struct dentry *dentry; 201131e6b01fSNick Piggin 20122903ff01SAl Viro if (!f.file) 2013368ee9baSAl Viro return ERR_PTR(-EBADF); 201431e6b01fSNick Piggin 20152903ff01SAl Viro dentry = f.file->f_path.dentry; 201631e6b01fSNick Piggin 2017fd2f7cb5SAl Viro if (*s) { 201844b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 20192903ff01SAl Viro fdput(f); 2020368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2021f52e0c11SAl Viro } 20222903ff01SAl Viro } 20232903ff01SAl Viro 20242903ff01SAl Viro nd->path = f.file->f_path; 2025e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 20268b61e74fSAl Viro rcu_read_lock(); 202734a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 202834a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 20295590ff0dSUlrich Drepper } else { 20302903ff01SAl Viro path_get(&nd->path); 203134a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 20321da177e4SLinus Torvalds } 203334a26b99SAl Viro fdput(f); 2034368ee9baSAl Viro return s; 2035e41f7d4eSAl Viro } 2036e41f7d4eSAl Viro 203731e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 20384023bfc9SAl Viro if (!(flags & LOOKUP_RCU)) 2039368ee9baSAl Viro return s; 20404023bfc9SAl Viro if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) 2041368ee9baSAl Viro return s; 20424023bfc9SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 20434023bfc9SAl Viro nd->root.mnt = NULL; 20444023bfc9SAl Viro rcu_read_unlock(); 2045368ee9baSAl Viro return ERR_PTR(-ECHILD); 20469b4a9b14SAl Viro } 20479b4a9b14SAl Viro 2048893b7775SAl Viro static void path_cleanup(struct nameidata *nd) 2049893b7775SAl Viro { 2050893b7775SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 2051893b7775SAl Viro path_put(&nd->root); 2052893b7775SAl Viro nd->root.mnt = NULL; 2053893b7775SAl Viro } 20549b4a9b14SAl Viro } 20559b4a9b14SAl Viro 20563bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 205795fa25d9SAl Viro { 205895fa25d9SAl Viro const char *s; 2059fec2fa24SAl Viro int error = may_follow_link(nd); 2060deb106c6SAl Viro if (unlikely(error)) 20613bdba28bSAl Viro return ERR_PTR(error); 206295fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2063fab51e8aSAl Viro nd->stack[0].name = NULL; 20643b2e7f75SAl Viro s = get_link(nd); 2065deb106c6SAl Viro return s ? s : ""; 206695fa25d9SAl Viro } 206795fa25d9SAl Viro 2068caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2069bd92d7feSAl Viro { 2070bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2071bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2072bd92d7feSAl Viro 2073bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 2074deb106c6SAl Viro return walk_component(nd, 20754693a547SAl Viro nd->flags & LOOKUP_FOLLOW 20764693a547SAl Viro ? nd->depth 20774693a547SAl Viro ? WALK_PUT | WALK_GET 20784693a547SAl Viro : WALK_GET 20794693a547SAl Viro : 0); 2080bd92d7feSAl Viro } 2081bd92d7feSAl Viro 20829b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 20835eb6b495SAl Viro static int path_lookupat(int dfd, const struct filename *name, 20849b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 20859b4a9b14SAl Viro { 2086368ee9baSAl Viro const char *s = path_init(dfd, name, flags, nd); 2087bd92d7feSAl Viro int err; 208831e6b01fSNick Piggin 2089368ee9baSAl Viro if (IS_ERR(s)) 2090368ee9baSAl Viro return PTR_ERR(s); 20913bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 20923bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 20933bdba28bSAl Viro s = trailing_symlink(nd); 20943bdba28bSAl Viro if (IS_ERR(s)) { 20953bdba28bSAl Viro err = PTR_ERR(s); 20966d7b5aaeSAl Viro break; 2097bd92d7feSAl Viro } 2098bd92d7feSAl Viro } 20999f1fafeeSAl Viro if (!err) 21009f1fafeeSAl Viro err = complete_walk(nd); 2101bd92d7feSAl Viro 2102deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2103deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2104bd23a539SAl Viro err = -ENOTDIR; 2105deb106c6SAl Viro if (err) 2106deb106c6SAl Viro terminate_walk(nd); 210716c2cd71SAl Viro 2108893b7775SAl Viro path_cleanup(nd); 2109bd92d7feSAl Viro return err; 211031e6b01fSNick Piggin } 211131e6b01fSNick Piggin 2112873f1eedSJeff Layton static int filename_lookup(int dfd, struct filename *name, 2113873f1eedSJeff Layton unsigned int flags, struct nameidata *nd) 2114873f1eedSJeff Layton { 2115894bc8c4SAl Viro int retval; 2116756daf26SNeilBrown struct nameidata *saved_nd = set_nameidata(nd); 2117894bc8c4SAl Viro 2118894bc8c4SAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 2119873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 21205eb6b495SAl Viro retval = path_lookupat(dfd, name, flags, nd); 2121873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 21225eb6b495SAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 2123873f1eedSJeff Layton 2124873f1eedSJeff Layton if (likely(!retval)) 2125adb5c247SJeff Layton audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); 2126756daf26SNeilBrown restore_nameidata(saved_nd); 2127873f1eedSJeff Layton return retval; 2128873f1eedSJeff Layton } 2129873f1eedSJeff Layton 21308bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 21318bcb77faSAl Viro static int path_parentat(int dfd, const struct filename *name, 21328bcb77faSAl Viro unsigned int flags, struct nameidata *nd) 21338bcb77faSAl Viro { 2134368ee9baSAl Viro const char *s = path_init(dfd, name, flags, nd); 2135368ee9baSAl Viro int err; 2136368ee9baSAl Viro if (IS_ERR(s)) 2137368ee9baSAl Viro return PTR_ERR(s); 2138368ee9baSAl Viro err = link_path_walk(s, nd); 21398bcb77faSAl Viro if (!err) 21408bcb77faSAl Viro err = complete_walk(nd); 2141deb106c6SAl Viro if (err) 2142deb106c6SAl Viro terminate_walk(nd); 21438bcb77faSAl Viro path_cleanup(nd); 21448bcb77faSAl Viro return err; 21458bcb77faSAl Viro } 21468bcb77faSAl Viro 21478bcb77faSAl Viro static int filename_parentat(int dfd, struct filename *name, 21488bcb77faSAl Viro unsigned int flags, struct nameidata *nd) 21498bcb77faSAl Viro { 21508bcb77faSAl Viro int retval; 21518bcb77faSAl Viro struct nameidata *saved_nd = set_nameidata(nd); 21528bcb77faSAl Viro 21538bcb77faSAl Viro retval = path_parentat(dfd, name, flags | LOOKUP_RCU, nd); 21548bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 21558bcb77faSAl Viro retval = path_parentat(dfd, name, flags, nd); 21568bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 21578bcb77faSAl Viro retval = path_parentat(dfd, name, flags | LOOKUP_REVAL, nd); 21588bcb77faSAl Viro 21598bcb77faSAl Viro if (likely(!retval)) 21608bcb77faSAl Viro audit_inode(name, nd->path.dentry, LOOKUP_PARENT); 21618bcb77faSAl Viro restore_nameidata(saved_nd); 21628bcb77faSAl Viro return retval; 21638bcb77faSAl Viro } 21648bcb77faSAl Viro 216579714f72SAl Viro /* does lookup, returns the object with parent locked */ 216679714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 21675590ff0dSUlrich Drepper { 216851689104SPaul Moore struct filename *filename = getname_kernel(name); 216979714f72SAl Viro struct nameidata nd; 217079714f72SAl Viro struct dentry *d; 217151689104SPaul Moore int err; 217251689104SPaul Moore 217351689104SPaul Moore if (IS_ERR(filename)) 217451689104SPaul Moore return ERR_CAST(filename); 217551689104SPaul Moore 21768bcb77faSAl Viro err = filename_parentat(AT_FDCWD, filename, 0, &nd); 217751689104SPaul Moore if (err) { 217851689104SPaul Moore d = ERR_PTR(err); 217951689104SPaul Moore goto out; 218051689104SPaul Moore } 218179714f72SAl Viro if (nd.last_type != LAST_NORM) { 218279714f72SAl Viro path_put(&nd.path); 218351689104SPaul Moore d = ERR_PTR(-EINVAL); 218451689104SPaul Moore goto out; 218579714f72SAl Viro } 218679714f72SAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 21871e0ea001SAl Viro d = __lookup_hash(&nd.last, nd.path.dentry, 0); 218879714f72SAl Viro if (IS_ERR(d)) { 218979714f72SAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 219079714f72SAl Viro path_put(&nd.path); 219151689104SPaul Moore goto out; 219279714f72SAl Viro } 219379714f72SAl Viro *path = nd.path; 219451689104SPaul Moore out: 219551689104SPaul Moore putname(filename); 219679714f72SAl Viro return d; 21975590ff0dSUlrich Drepper } 21985590ff0dSUlrich Drepper 2199d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2200d1811465SAl Viro { 2201d1811465SAl Viro struct nameidata nd; 220274eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 220374eb8cc5SAl Viro int res = PTR_ERR(filename); 220474eb8cc5SAl Viro 220574eb8cc5SAl Viro if (!IS_ERR(filename)) { 220674eb8cc5SAl Viro res = filename_lookup(AT_FDCWD, filename, flags, &nd); 220774eb8cc5SAl Viro putname(filename); 2208d1811465SAl Viro if (!res) 2209d1811465SAl Viro *path = nd.path; 221074eb8cc5SAl Viro } 2211d1811465SAl Viro return res; 2212d1811465SAl Viro } 22134d359507SAl Viro EXPORT_SYMBOL(kern_path); 2214d1811465SAl Viro 221516f18200SJosef 'Jeff' Sipek /** 221616f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 221716f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 221816f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 221916f18200SJosef 'Jeff' Sipek * @name: pointer to file name 222016f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2221e0a01249SAl Viro * @path: pointer to struct path to fill 222216f18200SJosef 'Jeff' Sipek */ 222316f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 222416f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2225e0a01249SAl Viro struct path *path) 222616f18200SJosef 'Jeff' Sipek { 222774eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 222874eb8cc5SAl Viro int err = PTR_ERR(filename); 222974eb8cc5SAl Viro 223074eb8cc5SAl Viro BUG_ON(flags & LOOKUP_PARENT); 223174eb8cc5SAl Viro 223274eb8cc5SAl Viro /* the first argument of filename_lookup() is ignored with LOOKUP_ROOT */ 223374eb8cc5SAl Viro if (!IS_ERR(filename)) { 2234e0a01249SAl Viro struct nameidata nd; 2235e0a01249SAl Viro nd.root.dentry = dentry; 2236e0a01249SAl Viro nd.root.mnt = mnt; 223774eb8cc5SAl Viro err = filename_lookup(AT_FDCWD, filename, 223874eb8cc5SAl Viro flags | LOOKUP_ROOT, &nd); 2239e0a01249SAl Viro if (!err) 2240e0a01249SAl Viro *path = nd.path; 224174eb8cc5SAl Viro putname(filename); 224274eb8cc5SAl Viro } 2243e0a01249SAl Viro return err; 224416f18200SJosef 'Jeff' Sipek } 22454d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 224616f18200SJosef 'Jeff' Sipek 2247eead1911SChristoph Hellwig /** 2248a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2249eead1911SChristoph Hellwig * @name: pathname component to lookup 2250eead1911SChristoph Hellwig * @base: base directory to lookup from 2251eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2252eead1911SChristoph Hellwig * 2253a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 22549e7543e9SAl Viro * not be called by generic code. 2255eead1911SChristoph Hellwig */ 2256057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2257057f6c01SJames Morris { 2258057f6c01SJames Morris struct qstr this; 22596a96ba54SAl Viro unsigned int c; 2260cda309deSMiklos Szeredi int err; 2261057f6c01SJames Morris 22622f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 22632f9092e1SDavid Woodhouse 22646a96ba54SAl Viro this.name = name; 22656a96ba54SAl Viro this.len = len; 22660145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 22676a96ba54SAl Viro if (!len) 22686a96ba54SAl Viro return ERR_PTR(-EACCES); 22696a96ba54SAl Viro 227021d8a15aSAl Viro if (unlikely(name[0] == '.')) { 227121d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 227221d8a15aSAl Viro return ERR_PTR(-EACCES); 227321d8a15aSAl Viro } 227421d8a15aSAl Viro 22756a96ba54SAl Viro while (len--) { 22766a96ba54SAl Viro c = *(const unsigned char *)name++; 22776a96ba54SAl Viro if (c == '/' || c == '\0') 22786a96ba54SAl Viro return ERR_PTR(-EACCES); 22796a96ba54SAl Viro } 22805a202bcdSAl Viro /* 22815a202bcdSAl Viro * See if the low-level filesystem might want 22825a202bcdSAl Viro * to use its own hash.. 22835a202bcdSAl Viro */ 22845a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2285da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 22865a202bcdSAl Viro if (err < 0) 22875a202bcdSAl Viro return ERR_PTR(err); 22885a202bcdSAl Viro } 2289eead1911SChristoph Hellwig 2290cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2291cda309deSMiklos Szeredi if (err) 2292cda309deSMiklos Szeredi return ERR_PTR(err); 2293cda309deSMiklos Szeredi 229472bd866aSAl Viro return __lookup_hash(&this, base, 0); 2295057f6c01SJames Morris } 22964d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2297057f6c01SJames Morris 22981fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 22991fa1e7f6SAndy Whitcroft struct path *path, int *empty) 23001da177e4SLinus Torvalds { 23012d8f3038SAl Viro struct nameidata nd; 230291a27b2aSJeff Layton struct filename *tmp = getname_flags(name, flags, empty); 23031da177e4SLinus Torvalds int err = PTR_ERR(tmp); 23041da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 23052d8f3038SAl Viro 23062d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 23072d8f3038SAl Viro 2308873f1eedSJeff Layton err = filename_lookup(dfd, tmp, flags, &nd); 23091da177e4SLinus Torvalds putname(tmp); 23102d8f3038SAl Viro if (!err) 23112d8f3038SAl Viro *path = nd.path; 23121da177e4SLinus Torvalds } 23131da177e4SLinus Torvalds return err; 23141da177e4SLinus Torvalds } 23151da177e4SLinus Torvalds 23161fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 23171fa1e7f6SAndy Whitcroft struct path *path) 23181fa1e7f6SAndy Whitcroft { 2319f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 23201fa1e7f6SAndy Whitcroft } 23214d359507SAl Viro EXPORT_SYMBOL(user_path_at); 23221fa1e7f6SAndy Whitcroft 2323873f1eedSJeff Layton /* 2324873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2325873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2326873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2327873f1eedSJeff Layton * path-walking is complete. 2328873f1eedSJeff Layton */ 232991a27b2aSJeff Layton static struct filename * 2330f5beed75SAl Viro user_path_parent(int dfd, const char __user *path, 2331f5beed75SAl Viro struct path *parent, 2332f5beed75SAl Viro struct qstr *last, 2333f5beed75SAl Viro int *type, 23349e790bd6SJeff Layton unsigned int flags) 23352ad94ae6SAl Viro { 2336f5beed75SAl Viro struct nameidata nd; 233791a27b2aSJeff Layton struct filename *s = getname(path); 23382ad94ae6SAl Viro int error; 23392ad94ae6SAl Viro 23409e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 23419e790bd6SJeff Layton flags &= LOOKUP_REVAL; 23429e790bd6SJeff Layton 23432ad94ae6SAl Viro if (IS_ERR(s)) 234491a27b2aSJeff Layton return s; 23452ad94ae6SAl Viro 23468bcb77faSAl Viro error = filename_parentat(dfd, s, flags, &nd); 234791a27b2aSJeff Layton if (error) { 23482ad94ae6SAl Viro putname(s); 234991a27b2aSJeff Layton return ERR_PTR(error); 235091a27b2aSJeff Layton } 2351f5beed75SAl Viro *parent = nd.path; 2352f5beed75SAl Viro *last = nd.last; 2353f5beed75SAl Viro *type = nd.last_type; 23542ad94ae6SAl Viro 235591a27b2aSJeff Layton return s; 23562ad94ae6SAl Viro } 23572ad94ae6SAl Viro 23588033426eSJeff Layton /** 2359197df04cSAl Viro * mountpoint_last - look up last component for umount 23608033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 23618033426eSJeff Layton * @path: pointer to container for result 23628033426eSJeff Layton * 23638033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 23648033426eSJeff Layton * need to resolve the path without doing any revalidation. 23658033426eSJeff Layton * 23668033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 23678033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 23688033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 23698033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 23708033426eSJeff Layton * bogus and it doesn't exist. 23718033426eSJeff Layton * 23728033426eSJeff Layton * Returns: 23738033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 23748033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 23758033426eSJeff Layton * put in this case. 23768033426eSJeff Layton * 23778033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 23788033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 23798033426eSJeff Layton * The nd->path reference will also be put. 23808033426eSJeff Layton * 23818033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 23828033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 23838033426eSJeff Layton * to the link, and nd->path will *not* be put. 23848033426eSJeff Layton */ 23858033426eSJeff Layton static int 2386197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 23878033426eSJeff Layton { 23888033426eSJeff Layton int error = 0; 23898033426eSJeff Layton struct dentry *dentry; 23908033426eSJeff Layton struct dentry *dir = nd->path.dentry; 23918033426eSJeff Layton 239235759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 239335759521SAl Viro if (nd->flags & LOOKUP_RCU) { 23946e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 2395deb106c6SAl Viro return -ECHILD; 23968033426eSJeff Layton } 23978033426eSJeff Layton 23988033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 23998033426eSJeff Layton 24008033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 24018033426eSJeff Layton error = handle_dots(nd, nd->last_type); 240235759521SAl Viro if (error) 2403deb106c6SAl Viro return error; 24048033426eSJeff Layton dentry = dget(nd->path.dentry); 240535759521SAl Viro goto done; 24068033426eSJeff Layton } 24078033426eSJeff Layton 24088033426eSJeff Layton mutex_lock(&dir->d_inode->i_mutex); 24098033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 24108033426eSJeff Layton if (!dentry) { 24118033426eSJeff Layton /* 24128033426eSJeff Layton * No cached dentry. Mounted dentries are pinned in the cache, 24138033426eSJeff Layton * so that means that this dentry is probably a symlink or the 24148033426eSJeff Layton * path doesn't actually point to a mounted dentry. 24158033426eSJeff Layton */ 24168033426eSJeff Layton dentry = d_alloc(dir, &nd->last); 24178033426eSJeff Layton if (!dentry) { 2418bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 2419deb106c6SAl Viro return -ENOMEM; 24208033426eSJeff Layton } 242135759521SAl Viro dentry = lookup_real(dir->d_inode, dentry, nd->flags); 2422bcceeebaSDave Jones if (IS_ERR(dentry)) { 2423bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 2424deb106c6SAl Viro return PTR_ERR(dentry); 24258033426eSJeff Layton } 2426bcceeebaSDave Jones } 24278033426eSJeff Layton mutex_unlock(&dir->d_inode->i_mutex); 24288033426eSJeff Layton 242935759521SAl Viro done: 2430698934dfSDavid Howells if (d_is_negative(dentry)) { 24318033426eSJeff Layton dput(dentry); 2432deb106c6SAl Viro return -ENOENT; 243335759521SAl Viro } 2434191d7f73SAl Viro if (nd->depth) 2435191d7f73SAl Viro put_link(nd); 24368033426eSJeff Layton path->dentry = dentry; 2437295dc39dSVasily Averin path->mnt = nd->path.mnt; 2438181548c0SAl Viro error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW, 2439181548c0SAl Viro d_backing_inode(dentry), 0); 2440deb106c6SAl Viro if (unlikely(error)) 2441d63ff28fSAl Viro return error; 2442295dc39dSVasily Averin mntget(path->mnt); 24438033426eSJeff Layton follow_mount(path); 2444deb106c6SAl Viro return 0; 24458033426eSJeff Layton } 24468033426eSJeff Layton 24478033426eSJeff Layton /** 2448197df04cSAl Viro * path_mountpoint - look up a path to be umounted 24498033426eSJeff Layton * @dfd: directory file descriptor to start walk from 24508033426eSJeff Layton * @name: full pathname to walk 2451606d6fe3SRandy Dunlap * @path: pointer to container for result 24528033426eSJeff Layton * @flags: lookup flags 24538033426eSJeff Layton * 24548033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2455606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 24568033426eSJeff Layton */ 24578033426eSJeff Layton static int 2458668696dcSAl Viro path_mountpoint(int dfd, const struct filename *name, struct path *path, 245946afd6f6SAl Viro struct nameidata *nd, unsigned int flags) 24608033426eSJeff Layton { 2461368ee9baSAl Viro const char *s = path_init(dfd, name, flags, nd); 2462368ee9baSAl Viro int err; 2463368ee9baSAl Viro if (IS_ERR(s)) 2464368ee9baSAl Viro return PTR_ERR(s); 24653bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 24663bdba28bSAl Viro (err = mountpoint_last(nd, path)) > 0) { 24673bdba28bSAl Viro s = trailing_symlink(nd); 24683bdba28bSAl Viro if (IS_ERR(s)) { 24693bdba28bSAl Viro err = PTR_ERR(s); 24708033426eSJeff Layton break; 24718033426eSJeff Layton } 24723bdba28bSAl Viro } 2473deb106c6SAl Viro terminate_walk(nd); 247446afd6f6SAl Viro path_cleanup(nd); 24758033426eSJeff Layton return err; 24768033426eSJeff Layton } 24778033426eSJeff Layton 24782d864651SAl Viro static int 2479668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 24802d864651SAl Viro unsigned int flags) 24812d864651SAl Viro { 2482756daf26SNeilBrown struct nameidata nd, *saved; 2483cbaab2dbSAl Viro int error; 2484668696dcSAl Viro if (IS_ERR(name)) 2485668696dcSAl Viro return PTR_ERR(name); 2486756daf26SNeilBrown saved = set_nameidata(&nd); 248746afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_RCU); 24882d864651SAl Viro if (unlikely(error == -ECHILD)) 248946afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags); 24902d864651SAl Viro if (unlikely(error == -ESTALE)) 249146afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_REVAL); 24922d864651SAl Viro if (likely(!error)) 2493668696dcSAl Viro audit_inode(name, path->dentry, 0); 2494756daf26SNeilBrown restore_nameidata(saved); 2495668696dcSAl Viro putname(name); 24962d864651SAl Viro return error; 24972d864651SAl Viro } 24982d864651SAl Viro 24998033426eSJeff Layton /** 2500197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 25018033426eSJeff Layton * @dfd: directory file descriptor 25028033426eSJeff Layton * @name: pathname from userland 25038033426eSJeff Layton * @flags: lookup flags 25048033426eSJeff Layton * @path: pointer to container to hold result 25058033426eSJeff Layton * 25068033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 25078033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 25088033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 25098033426eSJeff Layton * and avoid revalidating the last component. 25108033426eSJeff Layton * 25118033426eSJeff Layton * Returns 0 and populates "path" on success. 25128033426eSJeff Layton */ 25138033426eSJeff Layton int 2514197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 25158033426eSJeff Layton struct path *path) 25168033426eSJeff Layton { 2517cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 25188033426eSJeff Layton } 25198033426eSJeff Layton 25202d864651SAl Viro int 25212d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 25222d864651SAl Viro unsigned int flags) 25232d864651SAl Viro { 2524cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 25252d864651SAl Viro } 25262d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 25272d864651SAl Viro 2528cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 25291da177e4SLinus Torvalds { 25308e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2531da9592edSDavid Howells 25328e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 25331da177e4SLinus Torvalds return 0; 25348e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 25351da177e4SLinus Torvalds return 0; 253623adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 25371da177e4SLinus Torvalds } 2538cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 25391da177e4SLinus Torvalds 25401da177e4SLinus Torvalds /* 25411da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 25421da177e4SLinus Torvalds * whether the type of victim is right. 25431da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 25441da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 25451da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 25461da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 25471da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 25481da177e4SLinus Torvalds * a. be owner of dir, or 25491da177e4SLinus Torvalds * b. be owner of victim, or 25501da177e4SLinus Torvalds * c. have CAP_FOWNER capability 25511da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 25521da177e4SLinus Torvalds * links pointing to it. 25531da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 25541da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 25551da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 25561da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 25571da177e4SLinus Torvalds * nfs_async_unlink(). 25581da177e4SLinus Torvalds */ 2559b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 25601da177e4SLinus Torvalds { 256163afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 25621da177e4SLinus Torvalds int error; 25631da177e4SLinus Torvalds 2564b18825a7SDavid Howells if (d_is_negative(victim)) 25651da177e4SLinus Torvalds return -ENOENT; 2566b18825a7SDavid Howells BUG_ON(!inode); 25671da177e4SLinus Torvalds 25681da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 25694fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 25701da177e4SLinus Torvalds 2571f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 25721da177e4SLinus Torvalds if (error) 25731da177e4SLinus Torvalds return error; 25741da177e4SLinus Torvalds if (IS_APPEND(dir)) 25751da177e4SLinus Torvalds return -EPERM; 2576b18825a7SDavid Howells 2577b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2578b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 25791da177e4SLinus Torvalds return -EPERM; 25801da177e4SLinus Torvalds if (isdir) { 258144b1d530SMiklos Szeredi if (!d_is_dir(victim)) 25821da177e4SLinus Torvalds return -ENOTDIR; 25831da177e4SLinus Torvalds if (IS_ROOT(victim)) 25841da177e4SLinus Torvalds return -EBUSY; 258544b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 25861da177e4SLinus Torvalds return -EISDIR; 25871da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25881da177e4SLinus Torvalds return -ENOENT; 25891da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 25901da177e4SLinus Torvalds return -EBUSY; 25911da177e4SLinus Torvalds return 0; 25921da177e4SLinus Torvalds } 25931da177e4SLinus Torvalds 25941da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 25951da177e4SLinus Torvalds * dir. 25961da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 25971da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 25981da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 25991da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 26001da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 26011da177e4SLinus Torvalds */ 2602a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 26031da177e4SLinus Torvalds { 260414e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 26051da177e4SLinus Torvalds if (child->d_inode) 26061da177e4SLinus Torvalds return -EEXIST; 26071da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 26081da177e4SLinus Torvalds return -ENOENT; 2609f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 26101da177e4SLinus Torvalds } 26111da177e4SLinus Torvalds 26121da177e4SLinus Torvalds /* 26131da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 26141da177e4SLinus Torvalds */ 26151da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 26161da177e4SLinus Torvalds { 26171da177e4SLinus Torvalds struct dentry *p; 26181da177e4SLinus Torvalds 26191da177e4SLinus Torvalds if (p1 == p2) { 2620f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 26211da177e4SLinus Torvalds return NULL; 26221da177e4SLinus Torvalds } 26231da177e4SLinus Torvalds 2624a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 26251da177e4SLinus Torvalds 2626e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2627e2761a11SOGAWA Hirofumi if (p) { 2628f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2629f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 26301da177e4SLinus Torvalds return p; 26311da177e4SLinus Torvalds } 26321da177e4SLinus Torvalds 2633e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2634e2761a11SOGAWA Hirofumi if (p) { 2635f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2636f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 26371da177e4SLinus Torvalds return p; 26381da177e4SLinus Torvalds } 26391da177e4SLinus Torvalds 2640f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2641d1b72cc6SMiklos Szeredi mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); 26421da177e4SLinus Torvalds return NULL; 26431da177e4SLinus Torvalds } 26444d359507SAl Viro EXPORT_SYMBOL(lock_rename); 26451da177e4SLinus Torvalds 26461da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 26471da177e4SLinus Torvalds { 26481b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 26491da177e4SLinus Torvalds if (p1 != p2) { 26501b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2651a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 26521da177e4SLinus Torvalds } 26531da177e4SLinus Torvalds } 26544d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 26551da177e4SLinus Torvalds 26564acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2657312b63fbSAl Viro bool want_excl) 26581da177e4SLinus Torvalds { 2659a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 26601da177e4SLinus Torvalds if (error) 26611da177e4SLinus Torvalds return error; 26621da177e4SLinus Torvalds 2663acfa4380SAl Viro if (!dir->i_op->create) 26641da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 26651da177e4SLinus Torvalds mode &= S_IALLUGO; 26661da177e4SLinus Torvalds mode |= S_IFREG; 26671da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 26681da177e4SLinus Torvalds if (error) 26691da177e4SLinus Torvalds return error; 2670312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2671a74574aaSStephen Smalley if (!error) 2672f38aa942SAmy Griffis fsnotify_create(dir, dentry); 26731da177e4SLinus Torvalds return error; 26741da177e4SLinus Torvalds } 26754d359507SAl Viro EXPORT_SYMBOL(vfs_create); 26761da177e4SLinus Torvalds 267773d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 26781da177e4SLinus Torvalds { 26793fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 26801da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 26811da177e4SLinus Torvalds int error; 26821da177e4SLinus Torvalds 2683bcda7652SAl Viro /* O_PATH? */ 2684bcda7652SAl Viro if (!acc_mode) 2685bcda7652SAl Viro return 0; 2686bcda7652SAl Viro 26871da177e4SLinus Torvalds if (!inode) 26881da177e4SLinus Torvalds return -ENOENT; 26891da177e4SLinus Torvalds 2690c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2691c8fe8f30SChristoph Hellwig case S_IFLNK: 26921da177e4SLinus Torvalds return -ELOOP; 2693c8fe8f30SChristoph Hellwig case S_IFDIR: 2694c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 26951da177e4SLinus Torvalds return -EISDIR; 2696c8fe8f30SChristoph Hellwig break; 2697c8fe8f30SChristoph Hellwig case S_IFBLK: 2698c8fe8f30SChristoph Hellwig case S_IFCHR: 26993fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 27001da177e4SLinus Torvalds return -EACCES; 2701c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2702c8fe8f30SChristoph Hellwig case S_IFIFO: 2703c8fe8f30SChristoph Hellwig case S_IFSOCK: 27041da177e4SLinus Torvalds flag &= ~O_TRUNC; 2705c8fe8f30SChristoph Hellwig break; 27064a3fd211SDave Hansen } 2707b41572e9SDave Hansen 27083fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2709b41572e9SDave Hansen if (error) 2710b41572e9SDave Hansen return error; 27116146f0d5SMimi Zohar 27121da177e4SLinus Torvalds /* 27131da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 27141da177e4SLinus Torvalds */ 27151da177e4SLinus Torvalds if (IS_APPEND(inode)) { 27168737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 27177715b521SAl Viro return -EPERM; 27181da177e4SLinus Torvalds if (flag & O_TRUNC) 27197715b521SAl Viro return -EPERM; 27201da177e4SLinus Torvalds } 27211da177e4SLinus Torvalds 27221da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 27232e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 27247715b521SAl Viro return -EPERM; 27251da177e4SLinus Torvalds 2726f3c7691eSJ. Bruce Fields return 0; 27277715b521SAl Viro } 27287715b521SAl Viro 2729e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 27307715b521SAl Viro { 2731e1181ee6SJeff Layton struct path *path = &filp->f_path; 27327715b521SAl Viro struct inode *inode = path->dentry->d_inode; 27337715b521SAl Viro int error = get_write_access(inode); 27341da177e4SLinus Torvalds if (error) 27357715b521SAl Viro return error; 27361da177e4SLinus Torvalds /* 27371da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 27381da177e4SLinus Torvalds */ 2739d7a06983SJeff Layton error = locks_verify_locked(filp); 2740be6d3e56SKentaro Takeda if (!error) 2741ea0d3ab2STetsuo Handa error = security_path_truncate(path); 27421da177e4SLinus Torvalds if (!error) { 27437715b521SAl Viro error = do_truncate(path->dentry, 0, 2744d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2745e1181ee6SJeff Layton filp); 27461da177e4SLinus Torvalds } 27471da177e4SLinus Torvalds put_write_access(inode); 2748acd0c935SMimi Zohar return error; 27491da177e4SLinus Torvalds } 27501da177e4SLinus Torvalds 2751d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2752d57999e1SDave Hansen { 27538a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 27548a5e929dSAl Viro flag--; 2755d57999e1SDave Hansen return flag; 2756d57999e1SDave Hansen } 2757d57999e1SDave Hansen 2758d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2759d18e9008SMiklos Szeredi { 2760d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2761d18e9008SMiklos Szeredi if (error) 2762d18e9008SMiklos Szeredi return error; 2763d18e9008SMiklos Szeredi 2764d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2765d18e9008SMiklos Szeredi if (error) 2766d18e9008SMiklos Szeredi return error; 2767d18e9008SMiklos Szeredi 2768d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2769d18e9008SMiklos Szeredi } 2770d18e9008SMiklos Szeredi 27711acf0af9SDavid Howells /* 27721acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 27731acf0af9SDavid Howells * dentry. 27741acf0af9SDavid Howells * 27751acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 27761acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 27771acf0af9SDavid Howells * 27781acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 27791acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 27801acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 27811acf0af9SDavid Howells * 27821acf0af9SDavid Howells * Returns an error code otherwise. 27831acf0af9SDavid Howells */ 27842675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 278530d90494SAl Viro struct path *path, struct file *file, 2786015c3bbcSMiklos Szeredi const struct open_flags *op, 278764894cf8SAl Viro bool got_write, bool need_lookup, 278847237687SAl Viro int *opened) 2789d18e9008SMiklos Szeredi { 2790d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2791d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2792d18e9008SMiklos Szeredi umode_t mode; 2793d18e9008SMiklos Szeredi int error; 2794d18e9008SMiklos Szeredi int acc_mode; 2795d18e9008SMiklos Szeredi int create_error = 0; 2796d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2797116cc022SMiklos Szeredi bool excl; 2798d18e9008SMiklos Szeredi 2799d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2800d18e9008SMiklos Szeredi 2801d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2802d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 28032675a4ebSAl Viro error = -ENOENT; 2804d18e9008SMiklos Szeredi goto out; 2805d18e9008SMiklos Szeredi } 2806d18e9008SMiklos Szeredi 280762b259d8SMiklos Szeredi mode = op->mode; 2808d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2809d18e9008SMiklos Szeredi mode &= ~current_umask(); 2810d18e9008SMiklos Szeredi 2811116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2812116cc022SMiklos Szeredi if (excl) 2813d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2814d18e9008SMiklos Szeredi 2815d18e9008SMiklos Szeredi /* 2816d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2817d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2818d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2819d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2820d18e9008SMiklos Szeredi * 2821d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2822d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2823d18e9008SMiklos Szeredi */ 282464894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 282564894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 282664894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2827d18e9008SMiklos Szeredi /* 2828d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2829d18e9008SMiklos Szeredi * back to lookup + open 2830d18e9008SMiklos Szeredi */ 2831d18e9008SMiklos Szeredi goto no_open; 2832d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2833d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 283464894cf8SAl Viro create_error = -EROFS; 2835d18e9008SMiklos Szeredi goto no_open; 2836d18e9008SMiklos Szeredi } else { 2837d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 283864894cf8SAl Viro create_error = -EROFS; 2839d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2840d18e9008SMiklos Szeredi } 2841d18e9008SMiklos Szeredi } 2842d18e9008SMiklos Szeredi 2843d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 284438227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2845d18e9008SMiklos Szeredi if (error) { 2846d18e9008SMiklos Szeredi create_error = error; 2847d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2848d18e9008SMiklos Szeredi goto no_open; 2849d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2850d18e9008SMiklos Szeredi } 2851d18e9008SMiklos Szeredi } 2852d18e9008SMiklos Szeredi 2853d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2854d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2855d18e9008SMiklos Szeredi 285630d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 285730d90494SAl Viro file->f_path.mnt = nd->path.mnt; 285830d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 285947237687SAl Viro opened); 2860d9585277SAl Viro if (error < 0) { 2861d9585277SAl Viro if (create_error && error == -ENOENT) 2862d9585277SAl Viro error = create_error; 2863d18e9008SMiklos Szeredi goto out; 2864d18e9008SMiklos Szeredi } 2865d18e9008SMiklos Szeredi 2866d9585277SAl Viro if (error) { /* returned 1, that is */ 286730d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 28682675a4ebSAl Viro error = -EIO; 2869d18e9008SMiklos Szeredi goto out; 2870d18e9008SMiklos Szeredi } 287130d90494SAl Viro if (file->f_path.dentry) { 2872d18e9008SMiklos Szeredi dput(dentry); 287330d90494SAl Viro dentry = file->f_path.dentry; 2874d18e9008SMiklos Szeredi } 287503da633aSAl Viro if (*opened & FILE_CREATED) 287603da633aSAl Viro fsnotify_create(dir, dentry); 287703da633aSAl Viro if (!dentry->d_inode) { 287803da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 287903da633aSAl Viro if (create_error) { 288062b2ce96SSage Weil error = create_error; 288162b2ce96SSage Weil goto out; 288262b2ce96SSage Weil } 288303da633aSAl Viro } else { 288403da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 288503da633aSAl Viro error = -EEXIST; 288603da633aSAl Viro goto out; 288703da633aSAl Viro } 288803da633aSAl Viro } 2889d18e9008SMiklos Szeredi goto looked_up; 2890d18e9008SMiklos Szeredi } 2891d18e9008SMiklos Szeredi 2892d18e9008SMiklos Szeredi /* 2893d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2894d18e9008SMiklos Szeredi * here. 2895d18e9008SMiklos Szeredi */ 289603da633aSAl Viro acc_mode = op->acc_mode; 289703da633aSAl Viro if (*opened & FILE_CREATED) { 289803da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 289903da633aSAl Viro fsnotify_create(dir, dentry); 290003da633aSAl Viro acc_mode = MAY_OPEN; 290103da633aSAl Viro } 29022675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 29032675a4ebSAl Viro if (error) 29042675a4ebSAl Viro fput(file); 2905d18e9008SMiklos Szeredi 2906d18e9008SMiklos Szeredi out: 2907d18e9008SMiklos Szeredi dput(dentry); 29082675a4ebSAl Viro return error; 2909d18e9008SMiklos Szeredi 2910d18e9008SMiklos Szeredi no_open: 2911d18e9008SMiklos Szeredi if (need_lookup) { 291272bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2913d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 29142675a4ebSAl Viro return PTR_ERR(dentry); 2915d18e9008SMiklos Szeredi 2916d18e9008SMiklos Szeredi if (create_error) { 2917d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2918d18e9008SMiklos Szeredi 29192675a4ebSAl Viro error = create_error; 2920d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2921d18e9008SMiklos Szeredi if (!dentry->d_inode) 2922d18e9008SMiklos Szeredi goto out; 2923d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2924d18e9008SMiklos Szeredi goto out; 2925d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2926e36cb0b8SDavid Howells d_is_reg(dentry)) { 2927d18e9008SMiklos Szeredi goto out; 2928d18e9008SMiklos Szeredi } 2929d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2930d18e9008SMiklos Szeredi } 2931d18e9008SMiklos Szeredi } 2932d18e9008SMiklos Szeredi looked_up: 2933d18e9008SMiklos Szeredi path->dentry = dentry; 2934d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 29352675a4ebSAl Viro return 1; 2936d18e9008SMiklos Szeredi } 2937d18e9008SMiklos Szeredi 293831e6b01fSNick Piggin /* 29391acf0af9SDavid Howells * Look up and maybe create and open the last component. 2940d58ffd35SMiklos Szeredi * 2941d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2942d58ffd35SMiklos Szeredi * 29431acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 29441acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 29451acf0af9SDavid Howells * 29461acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 29471acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 29481acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 29491acf0af9SDavid Howells * specified then a negative dentry may be returned. 29501acf0af9SDavid Howells * 29511acf0af9SDavid Howells * An error code is returned otherwise. 29521acf0af9SDavid Howells * 29531acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 29541acf0af9SDavid Howells * cleared otherwise prior to returning. 2955d58ffd35SMiklos Szeredi */ 29562675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 295730d90494SAl Viro struct file *file, 2958d58ffd35SMiklos Szeredi const struct open_flags *op, 295964894cf8SAl Viro bool got_write, int *opened) 2960d58ffd35SMiklos Szeredi { 2961d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 296254ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2963d58ffd35SMiklos Szeredi struct dentry *dentry; 2964d58ffd35SMiklos Szeredi int error; 296554ef4872SMiklos Szeredi bool need_lookup; 2966d58ffd35SMiklos Szeredi 296747237687SAl Viro *opened &= ~FILE_CREATED; 2968201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2969d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 29702675a4ebSAl Viro return PTR_ERR(dentry); 2971d58ffd35SMiklos Szeredi 2972d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2973d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2974d18e9008SMiklos Szeredi goto out_no_open; 2975d18e9008SMiklos Szeredi 2976d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 297764894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 297847237687SAl Viro need_lookup, opened); 2979d18e9008SMiklos Szeredi } 2980d18e9008SMiklos Szeredi 298154ef4872SMiklos Szeredi if (need_lookup) { 298254ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 298354ef4872SMiklos Szeredi 298472bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 298554ef4872SMiklos Szeredi if (IS_ERR(dentry)) 29862675a4ebSAl Viro return PTR_ERR(dentry); 298754ef4872SMiklos Szeredi } 298854ef4872SMiklos Szeredi 2989d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2990d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2991d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2992d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2993d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2994d58ffd35SMiklos Szeredi /* 2995d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2996d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2997d58ffd35SMiklos Szeredi * the time when the file is created and when 2998d58ffd35SMiklos Szeredi * a permanent write count is taken through 2999015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 3000d58ffd35SMiklos Szeredi */ 300164894cf8SAl Viro if (!got_write) { 300264894cf8SAl Viro error = -EROFS; 3003d58ffd35SMiklos Szeredi goto out_dput; 300464894cf8SAl Viro } 300547237687SAl Viro *opened |= FILE_CREATED; 3006d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 3007d58ffd35SMiklos Szeredi if (error) 3008d58ffd35SMiklos Szeredi goto out_dput; 3009312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 3010312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 3011d58ffd35SMiklos Szeredi if (error) 3012d58ffd35SMiklos Szeredi goto out_dput; 3013d58ffd35SMiklos Szeredi } 3014d18e9008SMiklos Szeredi out_no_open: 3015d58ffd35SMiklos Szeredi path->dentry = dentry; 3016d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 30172675a4ebSAl Viro return 1; 3018d58ffd35SMiklos Szeredi 3019d58ffd35SMiklos Szeredi out_dput: 3020d58ffd35SMiklos Szeredi dput(dentry); 30212675a4ebSAl Viro return error; 3022d58ffd35SMiklos Szeredi } 3023d58ffd35SMiklos Szeredi 3024d58ffd35SMiklos Szeredi /* 3025fe2d35ffSAl Viro * Handle the last step of open() 302631e6b01fSNick Piggin */ 3027896475d5SAl Viro static int do_last(struct nameidata *nd, 302830d90494SAl Viro struct file *file, const struct open_flags *op, 3029669abf4eSJeff Layton int *opened, struct filename *name) 3030fb1cc555SAl Viro { 3031a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3032ca344a89SAl Viro int open_flag = op->open_flag; 303377d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 303464894cf8SAl Viro bool got_write = false; 3035bcda7652SAl Viro int acc_mode = op->acc_mode; 3036254cf582SAl Viro unsigned seq; 3037a1eb3315SMiklos Szeredi struct inode *inode; 303816b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 3039896475d5SAl Viro struct path path; 304016b1c1cdSMiklos Szeredi bool retried = false; 304116c2cd71SAl Viro int error; 3042fb1cc555SAl Viro 3043c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3044c3e380b0SAl Viro nd->flags |= op->intent; 3045c3e380b0SAl Viro 3046bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3047fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3048deb106c6SAl Viro if (unlikely(error)) 30492675a4ebSAl Viro return error; 3050e83db167SMiklos Szeredi goto finish_open; 30511f36f774SAl Viro } 3052a2c36b45SAl Viro 3053ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3054fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3055fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3056fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3057254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 305871574865SMiklos Szeredi if (likely(!error)) 305971574865SMiklos Szeredi goto finish_lookup; 306071574865SMiklos Szeredi 3061ce57dfc1SAl Viro if (error < 0) 3062deb106c6SAl Viro return error; 3063a1eb3315SMiklos Szeredi 306437d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 3065b6183df7SMiklos Szeredi } else { 3066fe2d35ffSAl Viro /* create side of things */ 3067a3fbbde7SAl Viro /* 3068b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3069b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3070b6183df7SMiklos Szeredi * about to look up 3071a3fbbde7SAl Viro */ 30729f1fafeeSAl Viro error = complete_walk(nd); 3073e8bb73dfSAl Viro if (error) 30742675a4ebSAl Viro return error; 3075fe2d35ffSAl Viro 307633e2208aSJeff Layton audit_inode(name, dir, LOOKUP_PARENT); 30771f36f774SAl Viro /* trailing slashes? */ 3078deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3079deb106c6SAl Viro return -EISDIR; 3080b6183df7SMiklos Szeredi } 30811f36f774SAl Viro 308216b1c1cdSMiklos Szeredi retry_lookup: 308364894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 308464894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 308564894cf8SAl Viro if (!error) 308664894cf8SAl Viro got_write = true; 308764894cf8SAl Viro /* 308864894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 308964894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 309064894cf8SAl Viro * dropping this one anyway. 309164894cf8SAl Viro */ 309264894cf8SAl Viro } 3093a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 3094896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 3095fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 3096fb1cc555SAl Viro 30972675a4ebSAl Viro if (error <= 0) { 30982675a4ebSAl Viro if (error) 3099d58ffd35SMiklos Szeredi goto out; 31006c0d46c4SAl Viro 310147237687SAl Viro if ((*opened & FILE_CREATED) || 3102496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 310377d660a8SMiklos Szeredi will_truncate = false; 3104d18e9008SMiklos Szeredi 3105adb5c247SJeff Layton audit_inode(name, file->f_path.dentry, 0); 3106d18e9008SMiklos Szeredi goto opened; 3107d18e9008SMiklos Szeredi } 3108d18e9008SMiklos Szeredi 310947237687SAl Viro if (*opened & FILE_CREATED) { 31109b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3111ca344a89SAl Viro open_flag &= ~O_TRUNC; 311277d660a8SMiklos Szeredi will_truncate = false; 3113bcda7652SAl Viro acc_mode = MAY_OPEN; 3114896475d5SAl Viro path_to_nameidata(&path, nd); 3115e83db167SMiklos Szeredi goto finish_open_created; 3116fb1cc555SAl Viro } 3117fb1cc555SAl Viro 3118fb1cc555SAl Viro /* 31193134f37eSJeff Layton * create/update audit record if it already exists. 3120fb1cc555SAl Viro */ 3121896475d5SAl Viro if (d_is_positive(path.dentry)) 3122896475d5SAl Viro audit_inode(name, path.dentry, 0); 3123fb1cc555SAl Viro 3124d18e9008SMiklos Szeredi /* 3125d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3126d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3127d18e9008SMiklos Szeredi * necessary...) 3128d18e9008SMiklos Szeredi */ 312964894cf8SAl Viro if (got_write) { 3130d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 313164894cf8SAl Viro got_write = false; 3132d18e9008SMiklos Szeredi } 3133d18e9008SMiklos Szeredi 3134deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3135deb106c6SAl Viro path_to_nameidata(&path, nd); 3136deb106c6SAl Viro return -EEXIST; 3137deb106c6SAl Viro } 3138fb1cc555SAl Viro 3139756daf26SNeilBrown error = follow_managed(&path, nd); 3140deb106c6SAl Viro if (unlikely(error < 0)) 3141deb106c6SAl Viro return error; 3142a3fbbde7SAl Viro 3143decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 314463afdfc7SDavid Howells inode = d_backing_inode(path.dentry); 3145254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3146deb106c6SAl Viro if (unlikely(d_is_negative(path.dentry))) { 3147896475d5SAl Viro path_to_nameidata(&path, nd); 3148deb106c6SAl Viro return -ENOENT; 314954c33e7fSMiklos Szeredi } 3150766c4cbfSAl Viro finish_lookup: 3151191d7f73SAl Viro if (nd->depth) 3152191d7f73SAl Viro put_link(nd); 3153181548c0SAl Viro error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW, 3154181548c0SAl Viro inode, seq); 3155deb106c6SAl Viro if (unlikely(error)) 3156d63ff28fSAl Viro return error; 3157fb1cc555SAl Viro 3158896475d5SAl Viro if (unlikely(d_is_symlink(path.dentry)) && !(open_flag & O_PATH)) { 3159896475d5SAl Viro path_to_nameidata(&path, nd); 3160deb106c6SAl Viro return -ELOOP; 3161a5cfe2d5SAl Viro } 3162a5cfe2d5SAl Viro 3163896475d5SAl Viro if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { 3164896475d5SAl Viro path_to_nameidata(&path, nd); 316516b1c1cdSMiklos Szeredi } else { 316616b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 3167896475d5SAl Viro save_parent.mnt = mntget(path.mnt); 3168896475d5SAl Viro nd->path.dentry = path.dentry; 316916b1c1cdSMiklos Szeredi 317016b1c1cdSMiklos Szeredi } 3171decf3400SMiklos Szeredi nd->inode = inode; 3172254cf582SAl Viro nd->seq = seq; 3173a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3174bc77daa7SAl Viro finish_open: 3175a3fbbde7SAl Viro error = complete_walk(nd); 317616b1c1cdSMiklos Szeredi if (error) { 317716b1c1cdSMiklos Szeredi path_put(&save_parent); 31782675a4ebSAl Viro return error; 317916b1c1cdSMiklos Szeredi } 3180bc77daa7SAl Viro audit_inode(name, nd->path.dentry, 0); 3181fb1cc555SAl Viro error = -EISDIR; 318244b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 31832675a4ebSAl Viro goto out; 3184af2f5542SMiklos Szeredi error = -ENOTDIR; 318544b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 31862675a4ebSAl Viro goto out; 31874bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 318877d660a8SMiklos Szeredi will_truncate = false; 31896c0d46c4SAl Viro 31900f9d1a10SAl Viro if (will_truncate) { 31910f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 31920f9d1a10SAl Viro if (error) 31932675a4ebSAl Viro goto out; 319464894cf8SAl Viro got_write = true; 31950f9d1a10SAl Viro } 3196e83db167SMiklos Szeredi finish_open_created: 3197bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3198ca344a89SAl Viro if (error) 31992675a4ebSAl Viro goto out; 32004aa7c634SMiklos Szeredi 32014aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 32024aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 32034aa7c634SMiklos Szeredi if (!error) { 32044aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 32054aa7c634SMiklos Szeredi } else { 320630d90494SAl Viro if (error == -EOPENSTALE) 3207f60dc3dbSMiklos Szeredi goto stale_open; 3208015c3bbcSMiklos Szeredi goto out; 3209f60dc3dbSMiklos Szeredi } 3210a8277b9bSMiklos Szeredi opened: 32112675a4ebSAl Viro error = open_check_o_direct(file); 3212015c3bbcSMiklos Szeredi if (error) 3213015c3bbcSMiklos Szeredi goto exit_fput; 32143034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3215aa4caadbSMiklos Szeredi if (error) 3216aa4caadbSMiklos Szeredi goto exit_fput; 3217aa4caadbSMiklos Szeredi 32180f9d1a10SAl Viro if (will_truncate) { 32192675a4ebSAl Viro error = handle_truncate(file); 3220aa4caadbSMiklos Szeredi if (error) 3221aa4caadbSMiklos Szeredi goto exit_fput; 32220f9d1a10SAl Viro } 3223ca344a89SAl Viro out: 322464894cf8SAl Viro if (got_write) 32250f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 322616b1c1cdSMiklos Szeredi path_put(&save_parent); 32272675a4ebSAl Viro return error; 3228fb1cc555SAl Viro 3229015c3bbcSMiklos Szeredi exit_fput: 32302675a4ebSAl Viro fput(file); 32312675a4ebSAl Viro goto out; 3232015c3bbcSMiklos Szeredi 3233f60dc3dbSMiklos Szeredi stale_open: 3234f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3235f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3236f60dc3dbSMiklos Szeredi goto out; 3237f60dc3dbSMiklos Szeredi 3238f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3239f60dc3dbSMiklos Szeredi path_put(&nd->path); 3240f60dc3dbSMiklos Szeredi nd->path = save_parent; 3241f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3242f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3243f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 324464894cf8SAl Viro if (got_write) { 3245f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 324664894cf8SAl Viro got_write = false; 3247f60dc3dbSMiklos Szeredi } 3248f60dc3dbSMiklos Szeredi retried = true; 3249f60dc3dbSMiklos Szeredi goto retry_lookup; 3250fb1cc555SAl Viro } 3251fb1cc555SAl Viro 325260545d0dSAl Viro static int do_tmpfile(int dfd, struct filename *pathname, 325360545d0dSAl Viro struct nameidata *nd, int flags, 325460545d0dSAl Viro const struct open_flags *op, 325560545d0dSAl Viro struct file *file, int *opened) 325660545d0dSAl Viro { 325760545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 325860545d0dSAl Viro struct dentry *dentry, *child; 325960545d0dSAl Viro struct inode *dir; 32605eb6b495SAl Viro int error = path_lookupat(dfd, pathname, 326160545d0dSAl Viro flags | LOOKUP_DIRECTORY, nd); 326260545d0dSAl Viro if (unlikely(error)) 326360545d0dSAl Viro return error; 326460545d0dSAl Viro error = mnt_want_write(nd->path.mnt); 326560545d0dSAl Viro if (unlikely(error)) 326660545d0dSAl Viro goto out; 326760545d0dSAl Viro /* we want directory to be writable */ 326860545d0dSAl Viro error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); 326960545d0dSAl Viro if (error) 327060545d0dSAl Viro goto out2; 327160545d0dSAl Viro dentry = nd->path.dentry; 327260545d0dSAl Viro dir = dentry->d_inode; 327360545d0dSAl Viro if (!dir->i_op->tmpfile) { 327460545d0dSAl Viro error = -EOPNOTSUPP; 327560545d0dSAl Viro goto out2; 327660545d0dSAl Viro } 327760545d0dSAl Viro child = d_alloc(dentry, &name); 327860545d0dSAl Viro if (unlikely(!child)) { 327960545d0dSAl Viro error = -ENOMEM; 328060545d0dSAl Viro goto out2; 328160545d0dSAl Viro } 328260545d0dSAl Viro nd->flags &= ~LOOKUP_DIRECTORY; 328360545d0dSAl Viro nd->flags |= op->intent; 328460545d0dSAl Viro dput(nd->path.dentry); 328560545d0dSAl Viro nd->path.dentry = child; 328660545d0dSAl Viro error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); 328760545d0dSAl Viro if (error) 328860545d0dSAl Viro goto out2; 328960545d0dSAl Viro audit_inode(pathname, nd->path.dentry, 0); 329069a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 329169a91c23SEric Rannaud error = may_open(&nd->path, MAY_OPEN, op->open_flag); 329260545d0dSAl Viro if (error) 329360545d0dSAl Viro goto out2; 329460545d0dSAl Viro file->f_path.mnt = nd->path.mnt; 329560545d0dSAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 329660545d0dSAl Viro if (error) 329760545d0dSAl Viro goto out2; 329860545d0dSAl Viro error = open_check_o_direct(file); 3299f4e0c30cSAl Viro if (error) { 330060545d0dSAl Viro fput(file); 3301f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3302f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3303f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3304f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3305f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3306f4e0c30cSAl Viro } 330760545d0dSAl Viro out2: 330860545d0dSAl Viro mnt_drop_write(nd->path.mnt); 330960545d0dSAl Viro out: 331060545d0dSAl Viro path_put(&nd->path); 331160545d0dSAl Viro return error; 331260545d0dSAl Viro } 331360545d0dSAl Viro 3314669abf4eSJeff Layton static struct file *path_openat(int dfd, struct filename *pathname, 331573d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 33161da177e4SLinus Torvalds { 3317368ee9baSAl Viro const char *s; 331830d90494SAl Viro struct file *file; 331947237687SAl Viro int opened = 0; 332013aab428SAl Viro int error; 332131e6b01fSNick Piggin 332230d90494SAl Viro file = get_empty_filp(); 33231afc99beSAl Viro if (IS_ERR(file)) 33241afc99beSAl Viro return file; 332531e6b01fSNick Piggin 332630d90494SAl Viro file->f_flags = op->open_flag; 332731e6b01fSNick Piggin 3328bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 332960545d0dSAl Viro error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); 3330f15133dfSAl Viro goto out2; 333160545d0dSAl Viro } 333260545d0dSAl Viro 3333368ee9baSAl Viro s = path_init(dfd, pathname, flags, nd); 3334368ee9baSAl Viro if (IS_ERR(s)) { 3335368ee9baSAl Viro put_filp(file); 3336368ee9baSAl Viro return ERR_CAST(s); 3337368ee9baSAl Viro } 33383bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 33393bdba28bSAl Viro (error = do_last(nd, file, op, &opened, pathname)) > 0) { 334073d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 33413bdba28bSAl Viro s = trailing_symlink(nd); 33423bdba28bSAl Viro if (IS_ERR(s)) { 33433bdba28bSAl Viro error = PTR_ERR(s); 33442675a4ebSAl Viro break; 3345806b681cSAl Viro } 33463bdba28bSAl Viro } 3347deb106c6SAl Viro terminate_walk(nd); 3348893b7775SAl Viro path_cleanup(nd); 3349f15133dfSAl Viro out2: 33502675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 33512675a4ebSAl Viro BUG_ON(!error); 335230d90494SAl Viro put_filp(file); 3353015c3bbcSMiklos Szeredi } 33542675a4ebSAl Viro if (unlikely(error)) { 33552675a4ebSAl Viro if (error == -EOPENSTALE) { 33562675a4ebSAl Viro if (flags & LOOKUP_RCU) 33572675a4ebSAl Viro error = -ECHILD; 33582675a4ebSAl Viro else 33592675a4ebSAl Viro error = -ESTALE; 33602675a4ebSAl Viro } 33612675a4ebSAl Viro file = ERR_PTR(error); 33622675a4ebSAl Viro } 33632675a4ebSAl Viro return file; 3364de459215SKirill Korotaev } 33651da177e4SLinus Torvalds 3366669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3367f9652e10SAl Viro const struct open_flags *op) 336813aab428SAl Viro { 3369756daf26SNeilBrown struct nameidata nd, *saved_nd = set_nameidata(&nd); 3370f9652e10SAl Viro int flags = op->lookup_flags; 337113aab428SAl Viro struct file *filp; 337213aab428SAl Viro 337373d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 337413aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 337573d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 337613aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 337773d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 3378756daf26SNeilBrown restore_nameidata(saved_nd); 337913aab428SAl Viro return filp; 338013aab428SAl Viro } 338113aab428SAl Viro 338273d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3383f9652e10SAl Viro const char *name, const struct open_flags *op) 338473d049a4SAl Viro { 3385756daf26SNeilBrown struct nameidata nd, *saved_nd; 338673d049a4SAl Viro struct file *file; 338751689104SPaul Moore struct filename *filename; 3388f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 338973d049a4SAl Viro 339073d049a4SAl Viro nd.root.mnt = mnt; 339173d049a4SAl Viro nd.root.dentry = dentry; 339273d049a4SAl Viro 3393b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 339473d049a4SAl Viro return ERR_PTR(-ELOOP); 339573d049a4SAl Viro 339651689104SPaul Moore filename = getname_kernel(name); 339751689104SPaul Moore if (unlikely(IS_ERR(filename))) 339851689104SPaul Moore return ERR_CAST(filename); 339951689104SPaul Moore 3400756daf26SNeilBrown saved_nd = set_nameidata(&nd); 340151689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_RCU); 340273d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 340351689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags); 340473d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 340551689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_REVAL); 3406756daf26SNeilBrown restore_nameidata(saved_nd); 340751689104SPaul Moore putname(filename); 340873d049a4SAl Viro return file; 340973d049a4SAl Viro } 341073d049a4SAl Viro 3411fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 34121ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 34131da177e4SLinus Torvalds { 3414c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3415ed75e95dSAl Viro struct nameidata nd; 3416c30dabfeSJan Kara int err2; 34171ac12b4bSJeff Layton int error; 34181ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 34191ac12b4bSJeff Layton 34201ac12b4bSJeff Layton /* 34211ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 34221ac12b4bSJeff Layton * other flags passed in are ignored! 34231ac12b4bSJeff Layton */ 34241ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 34251ac12b4bSJeff Layton 34268bcb77faSAl Viro error = filename_parentat(dfd, name, lookup_flags, &nd); 3427ed75e95dSAl Viro if (error) 3428ed75e95dSAl Viro return ERR_PTR(error); 34291da177e4SLinus Torvalds 3430c663e5d8SChristoph Hellwig /* 3431c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3432c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3433c663e5d8SChristoph Hellwig */ 3434ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 3435ed75e95dSAl Viro goto out; 3436ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 3437ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 3438c663e5d8SChristoph Hellwig 3439c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3440c30dabfeSJan Kara err2 = mnt_want_write(nd.path.mnt); 3441c663e5d8SChristoph Hellwig /* 3442c663e5d8SChristoph Hellwig * Do the final lookup. 3443c663e5d8SChristoph Hellwig */ 3444ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 34456a9f40d6SAl Viro dentry = __lookup_hash(&nd.last, nd.path.dentry, nd.flags); 34461da177e4SLinus Torvalds if (IS_ERR(dentry)) 3447a8104a9fSAl Viro goto unlock; 3448c663e5d8SChristoph Hellwig 3449a8104a9fSAl Viro error = -EEXIST; 3450b18825a7SDavid Howells if (d_is_positive(dentry)) 3451a8104a9fSAl Viro goto fail; 3452b18825a7SDavid Howells 3453c663e5d8SChristoph Hellwig /* 3454c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3455c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3456c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3457c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3458c663e5d8SChristoph Hellwig */ 3459ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 3460a8104a9fSAl Viro error = -ENOENT; 3461ed75e95dSAl Viro goto fail; 3462e9baf6e5SAl Viro } 3463c30dabfeSJan Kara if (unlikely(err2)) { 3464c30dabfeSJan Kara error = err2; 3465a8104a9fSAl Viro goto fail; 3466c30dabfeSJan Kara } 3467ed75e95dSAl Viro *path = nd.path; 3468e9baf6e5SAl Viro return dentry; 34691da177e4SLinus Torvalds fail: 3470a8104a9fSAl Viro dput(dentry); 3471a8104a9fSAl Viro dentry = ERR_PTR(error); 3472a8104a9fSAl Viro unlock: 3473dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3474c30dabfeSJan Kara if (!err2) 3475c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 3476ed75e95dSAl Viro out: 3477dae6ad8fSAl Viro path_put(&nd.path); 3478ed75e95dSAl Viro return dentry; 3479dae6ad8fSAl Viro } 3480fa14a0b8SAl Viro 3481fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3482fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3483fa14a0b8SAl Viro { 348451689104SPaul Moore struct filename *filename = getname_kernel(pathname); 348551689104SPaul Moore struct dentry *res; 348651689104SPaul Moore 348751689104SPaul Moore if (IS_ERR(filename)) 348851689104SPaul Moore return ERR_CAST(filename); 348951689104SPaul Moore res = filename_create(dfd, filename, path, lookup_flags); 349051689104SPaul Moore putname(filename); 349151689104SPaul Moore return res; 3492fa14a0b8SAl Viro } 3493dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3494dae6ad8fSAl Viro 3495921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3496921a1650SAl Viro { 3497921a1650SAl Viro dput(dentry); 3498921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3499a8104a9fSAl Viro mnt_drop_write(path->mnt); 3500921a1650SAl Viro path_put(path); 3501921a1650SAl Viro } 3502921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3503921a1650SAl Viro 35041ac12b4bSJeff Layton struct dentry *user_path_create(int dfd, const char __user *pathname, 35051ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3506dae6ad8fSAl Viro { 350791a27b2aSJeff Layton struct filename *tmp = getname(pathname); 3508dae6ad8fSAl Viro struct dentry *res; 3509dae6ad8fSAl Viro if (IS_ERR(tmp)) 3510dae6ad8fSAl Viro return ERR_CAST(tmp); 3511fa14a0b8SAl Viro res = filename_create(dfd, tmp, path, lookup_flags); 3512dae6ad8fSAl Viro putname(tmp); 3513dae6ad8fSAl Viro return res; 3514dae6ad8fSAl Viro } 3515dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3516dae6ad8fSAl Viro 35171a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 35181da177e4SLinus Torvalds { 3519a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35201da177e4SLinus Torvalds 35211da177e4SLinus Torvalds if (error) 35221da177e4SLinus Torvalds return error; 35231da177e4SLinus Torvalds 3524975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 35251da177e4SLinus Torvalds return -EPERM; 35261da177e4SLinus Torvalds 3527acfa4380SAl Viro if (!dir->i_op->mknod) 35281da177e4SLinus Torvalds return -EPERM; 35291da177e4SLinus Torvalds 353008ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 353108ce5f16SSerge E. Hallyn if (error) 353208ce5f16SSerge E. Hallyn return error; 353308ce5f16SSerge E. Hallyn 35341da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 35351da177e4SLinus Torvalds if (error) 35361da177e4SLinus Torvalds return error; 35371da177e4SLinus Torvalds 35381da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3539a74574aaSStephen Smalley if (!error) 3540f38aa942SAmy Griffis fsnotify_create(dir, dentry); 35411da177e4SLinus Torvalds return error; 35421da177e4SLinus Torvalds } 35434d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 35441da177e4SLinus Torvalds 3545f69aac00SAl Viro static int may_mknod(umode_t mode) 3546463c3197SDave Hansen { 3547463c3197SDave Hansen switch (mode & S_IFMT) { 3548463c3197SDave Hansen case S_IFREG: 3549463c3197SDave Hansen case S_IFCHR: 3550463c3197SDave Hansen case S_IFBLK: 3551463c3197SDave Hansen case S_IFIFO: 3552463c3197SDave Hansen case S_IFSOCK: 3553463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3554463c3197SDave Hansen return 0; 3555463c3197SDave Hansen case S_IFDIR: 3556463c3197SDave Hansen return -EPERM; 3557463c3197SDave Hansen default: 3558463c3197SDave Hansen return -EINVAL; 3559463c3197SDave Hansen } 3560463c3197SDave Hansen } 3561463c3197SDave Hansen 35628208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 35632e4d0924SHeiko Carstens unsigned, dev) 35641da177e4SLinus Torvalds { 35651da177e4SLinus Torvalds struct dentry *dentry; 3566dae6ad8fSAl Viro struct path path; 3567dae6ad8fSAl Viro int error; 3568972567f1SJeff Layton unsigned int lookup_flags = 0; 35691da177e4SLinus Torvalds 35708e4bfca1SAl Viro error = may_mknod(mode); 35718e4bfca1SAl Viro if (error) 35728e4bfca1SAl Viro return error; 3573972567f1SJeff Layton retry: 3574972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3575dae6ad8fSAl Viro if (IS_ERR(dentry)) 3576dae6ad8fSAl Viro return PTR_ERR(dentry); 35772ad94ae6SAl Viro 3578dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3579ce3b0f8dSAl Viro mode &= ~current_umask(); 3580dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3581be6d3e56SKentaro Takeda if (error) 3582a8104a9fSAl Viro goto out; 35831da177e4SLinus Torvalds switch (mode & S_IFMT) { 35841da177e4SLinus Torvalds case 0: case S_IFREG: 3585312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 35861da177e4SLinus Torvalds break; 35871da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3588dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 35891da177e4SLinus Torvalds new_decode_dev(dev)); 35901da177e4SLinus Torvalds break; 35911da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3592dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 35931da177e4SLinus Torvalds break; 35941da177e4SLinus Torvalds } 3595a8104a9fSAl Viro out: 3596921a1650SAl Viro done_path_create(&path, dentry); 3597972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3598972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3599972567f1SJeff Layton goto retry; 3600972567f1SJeff Layton } 36011da177e4SLinus Torvalds return error; 36021da177e4SLinus Torvalds } 36031da177e4SLinus Torvalds 36048208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 36055590ff0dSUlrich Drepper { 36065590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 36075590ff0dSUlrich Drepper } 36085590ff0dSUlrich Drepper 360918bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 36101da177e4SLinus Torvalds { 3611a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36128de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 36131da177e4SLinus Torvalds 36141da177e4SLinus Torvalds if (error) 36151da177e4SLinus Torvalds return error; 36161da177e4SLinus Torvalds 3617acfa4380SAl Viro if (!dir->i_op->mkdir) 36181da177e4SLinus Torvalds return -EPERM; 36191da177e4SLinus Torvalds 36201da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 36211da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 36221da177e4SLinus Torvalds if (error) 36231da177e4SLinus Torvalds return error; 36241da177e4SLinus Torvalds 36258de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 36268de52778SAl Viro return -EMLINK; 36278de52778SAl Viro 36281da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3629a74574aaSStephen Smalley if (!error) 3630f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 36311da177e4SLinus Torvalds return error; 36321da177e4SLinus Torvalds } 36334d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 36341da177e4SLinus Torvalds 3635a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 36361da177e4SLinus Torvalds { 36376902d925SDave Hansen struct dentry *dentry; 3638dae6ad8fSAl Viro struct path path; 3639dae6ad8fSAl Viro int error; 3640b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 36411da177e4SLinus Torvalds 3642b76d8b82SJeff Layton retry: 3643b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 36446902d925SDave Hansen if (IS_ERR(dentry)) 3645dae6ad8fSAl Viro return PTR_ERR(dentry); 36466902d925SDave Hansen 3647dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3648ce3b0f8dSAl Viro mode &= ~current_umask(); 3649dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3650a8104a9fSAl Viro if (!error) 3651dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3652921a1650SAl Viro done_path_create(&path, dentry); 3653b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3654b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3655b76d8b82SJeff Layton goto retry; 3656b76d8b82SJeff Layton } 36571da177e4SLinus Torvalds return error; 36581da177e4SLinus Torvalds } 36591da177e4SLinus Torvalds 3660a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 36615590ff0dSUlrich Drepper { 36625590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 36635590ff0dSUlrich Drepper } 36645590ff0dSUlrich Drepper 36651da177e4SLinus Torvalds /* 3666a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3667c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3668a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3669a71905f0SSage Weil * then we drop the dentry now. 36701da177e4SLinus Torvalds * 36711da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 36721da177e4SLinus Torvalds * do a 36731da177e4SLinus Torvalds * 36741da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 36751da177e4SLinus Torvalds * return -EBUSY; 36761da177e4SLinus Torvalds * 36771da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 36781da177e4SLinus Torvalds * that is still in use by something else.. 36791da177e4SLinus Torvalds */ 36801da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 36811da177e4SLinus Torvalds { 36821da177e4SLinus Torvalds shrink_dcache_parent(dentry); 36831da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 368498474236SWaiman Long if (dentry->d_lockref.count == 1) 36851da177e4SLinus Torvalds __d_drop(dentry); 36861da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 36871da177e4SLinus Torvalds } 36884d359507SAl Viro EXPORT_SYMBOL(dentry_unhash); 36891da177e4SLinus Torvalds 36901da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 36911da177e4SLinus Torvalds { 36921da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 36931da177e4SLinus Torvalds 36941da177e4SLinus Torvalds if (error) 36951da177e4SLinus Torvalds return error; 36961da177e4SLinus Torvalds 3697acfa4380SAl Viro if (!dir->i_op->rmdir) 36981da177e4SLinus Torvalds return -EPERM; 36991da177e4SLinus Torvalds 37001d2ef590SAl Viro dget(dentry); 37011b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3702912dbc15SSage Weil 37031da177e4SLinus Torvalds error = -EBUSY; 37047af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3705912dbc15SSage Weil goto out; 3706912dbc15SSage Weil 37071da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3708912dbc15SSage Weil if (error) 3709912dbc15SSage Weil goto out; 3710912dbc15SSage Weil 37113cebde24SSage Weil shrink_dcache_parent(dentry); 37121da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3713912dbc15SSage Weil if (error) 3714912dbc15SSage Weil goto out; 3715912dbc15SSage Weil 37161da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3717d83c49f3SAl Viro dont_mount(dentry); 37188ed936b5SEric W. Biederman detach_mounts(dentry); 37191da177e4SLinus Torvalds 3720912dbc15SSage Weil out: 3721912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 37221d2ef590SAl Viro dput(dentry); 3723912dbc15SSage Weil if (!error) 3724912dbc15SSage Weil d_delete(dentry); 37251da177e4SLinus Torvalds return error; 37261da177e4SLinus Torvalds } 37274d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 37281da177e4SLinus Torvalds 37295590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 37301da177e4SLinus Torvalds { 37311da177e4SLinus Torvalds int error = 0; 373291a27b2aSJeff Layton struct filename *name; 37331da177e4SLinus Torvalds struct dentry *dentry; 3734f5beed75SAl Viro struct path path; 3735f5beed75SAl Viro struct qstr last; 3736f5beed75SAl Viro int type; 3737c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3738c6ee9206SJeff Layton retry: 3739f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3740f5beed75SAl Viro &path, &last, &type, lookup_flags); 374191a27b2aSJeff Layton if (IS_ERR(name)) 374291a27b2aSJeff Layton return PTR_ERR(name); 37431da177e4SLinus Torvalds 3744f5beed75SAl Viro switch (type) { 37451da177e4SLinus Torvalds case LAST_DOTDOT: 37461da177e4SLinus Torvalds error = -ENOTEMPTY; 37471da177e4SLinus Torvalds goto exit1; 37481da177e4SLinus Torvalds case LAST_DOT: 37491da177e4SLinus Torvalds error = -EINVAL; 37501da177e4SLinus Torvalds goto exit1; 37511da177e4SLinus Torvalds case LAST_ROOT: 37521da177e4SLinus Torvalds error = -EBUSY; 37531da177e4SLinus Torvalds goto exit1; 37541da177e4SLinus Torvalds } 37550612d9fbSOGAWA Hirofumi 3756f5beed75SAl Viro error = mnt_want_write(path.mnt); 3757c30dabfeSJan Kara if (error) 3758c30dabfeSJan Kara goto exit1; 37590612d9fbSOGAWA Hirofumi 3760f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3761f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 37621da177e4SLinus Torvalds error = PTR_ERR(dentry); 37636902d925SDave Hansen if (IS_ERR(dentry)) 37646902d925SDave Hansen goto exit2; 3765e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3766e6bc45d6STheodore Ts'o error = -ENOENT; 3767e6bc45d6STheodore Ts'o goto exit3; 3768e6bc45d6STheodore Ts'o } 3769f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3770be6d3e56SKentaro Takeda if (error) 3771c30dabfeSJan Kara goto exit3; 3772f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 37730622753bSDave Hansen exit3: 37741da177e4SLinus Torvalds dput(dentry); 37756902d925SDave Hansen exit2: 3776f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 3777f5beed75SAl Viro mnt_drop_write(path.mnt); 37781da177e4SLinus Torvalds exit1: 3779f5beed75SAl Viro path_put(&path); 37801da177e4SLinus Torvalds putname(name); 3781c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3782c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3783c6ee9206SJeff Layton goto retry; 3784c6ee9206SJeff Layton } 37851da177e4SLinus Torvalds return error; 37861da177e4SLinus Torvalds } 37871da177e4SLinus Torvalds 37883cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 37895590ff0dSUlrich Drepper { 37905590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 37915590ff0dSUlrich Drepper } 37925590ff0dSUlrich Drepper 3793b21996e3SJ. Bruce Fields /** 3794b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3795b21996e3SJ. Bruce Fields * @dir: parent directory 3796b21996e3SJ. Bruce Fields * @dentry: victim 3797b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3798b21996e3SJ. Bruce Fields * 3799b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3800b21996e3SJ. Bruce Fields * 3801b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3802b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3803b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3804b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3805b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3806b21996e3SJ. Bruce Fields * 3807b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3808b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3809b21996e3SJ. Bruce Fields * to be NFS exported. 3810b21996e3SJ. Bruce Fields */ 3811b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 38121da177e4SLinus Torvalds { 38139accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 38141da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 38151da177e4SLinus Torvalds 38161da177e4SLinus Torvalds if (error) 38171da177e4SLinus Torvalds return error; 38181da177e4SLinus Torvalds 3819acfa4380SAl Viro if (!dir->i_op->unlink) 38201da177e4SLinus Torvalds return -EPERM; 38211da177e4SLinus Torvalds 38229accbb97SJ. Bruce Fields mutex_lock(&target->i_mutex); 38238ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 38241da177e4SLinus Torvalds error = -EBUSY; 38251da177e4SLinus Torvalds else { 38261da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3827bec1052eSAl Viro if (!error) { 38285a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 38295a14696cSJ. Bruce Fields if (error) 3830b21996e3SJ. Bruce Fields goto out; 38311da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 38328ed936b5SEric W. Biederman if (!error) { 3833d83c49f3SAl Viro dont_mount(dentry); 38348ed936b5SEric W. Biederman detach_mounts(dentry); 38358ed936b5SEric W. Biederman } 3836bec1052eSAl Viro } 38371da177e4SLinus Torvalds } 3838b21996e3SJ. Bruce Fields out: 38399accbb97SJ. Bruce Fields mutex_unlock(&target->i_mutex); 38401da177e4SLinus Torvalds 38411da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 38421da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 38439accbb97SJ. Bruce Fields fsnotify_link_count(target); 38441da177e4SLinus Torvalds d_delete(dentry); 38451da177e4SLinus Torvalds } 38460eeca283SRobert Love 38471da177e4SLinus Torvalds return error; 38481da177e4SLinus Torvalds } 38494d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 38501da177e4SLinus Torvalds 38511da177e4SLinus Torvalds /* 38521da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 38531b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 38541da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 38551da177e4SLinus Torvalds * while waiting on the I/O. 38561da177e4SLinus Torvalds */ 38575590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 38581da177e4SLinus Torvalds { 38592ad94ae6SAl Viro int error; 386091a27b2aSJeff Layton struct filename *name; 38611da177e4SLinus Torvalds struct dentry *dentry; 3862f5beed75SAl Viro struct path path; 3863f5beed75SAl Viro struct qstr last; 3864f5beed75SAl Viro int type; 38651da177e4SLinus Torvalds struct inode *inode = NULL; 3866b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 38675d18f813SJeff Layton unsigned int lookup_flags = 0; 38685d18f813SJeff Layton retry: 3869f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3870f5beed75SAl Viro &path, &last, &type, lookup_flags); 387191a27b2aSJeff Layton if (IS_ERR(name)) 387291a27b2aSJeff Layton return PTR_ERR(name); 38732ad94ae6SAl Viro 38741da177e4SLinus Torvalds error = -EISDIR; 3875f5beed75SAl Viro if (type != LAST_NORM) 38761da177e4SLinus Torvalds goto exit1; 38770612d9fbSOGAWA Hirofumi 3878f5beed75SAl Viro error = mnt_want_write(path.mnt); 3879c30dabfeSJan Kara if (error) 3880c30dabfeSJan Kara goto exit1; 3881b21996e3SJ. Bruce Fields retry_deleg: 3882f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3883f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38841da177e4SLinus Torvalds error = PTR_ERR(dentry); 38851da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 38861da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3887f5beed75SAl Viro if (last.name[last.len]) 388850338b88STörök Edwin goto slashes; 38891da177e4SLinus Torvalds inode = dentry->d_inode; 3890b18825a7SDavid Howells if (d_is_negative(dentry)) 3891e6bc45d6STheodore Ts'o goto slashes; 38927de9c6eeSAl Viro ihold(inode); 3893f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3894be6d3e56SKentaro Takeda if (error) 3895c30dabfeSJan Kara goto exit2; 3896f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 38971da177e4SLinus Torvalds exit2: 38981da177e4SLinus Torvalds dput(dentry); 38991da177e4SLinus Torvalds } 3900f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 39011da177e4SLinus Torvalds if (inode) 39021da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3903b21996e3SJ. Bruce Fields inode = NULL; 3904b21996e3SJ. Bruce Fields if (delegated_inode) { 39055a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3906b21996e3SJ. Bruce Fields if (!error) 3907b21996e3SJ. Bruce Fields goto retry_deleg; 3908b21996e3SJ. Bruce Fields } 3909f5beed75SAl Viro mnt_drop_write(path.mnt); 39101da177e4SLinus Torvalds exit1: 3911f5beed75SAl Viro path_put(&path); 39121da177e4SLinus Torvalds putname(name); 39135d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 39145d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 39155d18f813SJeff Layton inode = NULL; 39165d18f813SJeff Layton goto retry; 39175d18f813SJeff Layton } 39181da177e4SLinus Torvalds return error; 39191da177e4SLinus Torvalds 39201da177e4SLinus Torvalds slashes: 3921b18825a7SDavid Howells if (d_is_negative(dentry)) 3922b18825a7SDavid Howells error = -ENOENT; 392344b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3924b18825a7SDavid Howells error = -EISDIR; 3925b18825a7SDavid Howells else 3926b18825a7SDavid Howells error = -ENOTDIR; 39271da177e4SLinus Torvalds goto exit2; 39281da177e4SLinus Torvalds } 39291da177e4SLinus Torvalds 39302e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 39315590ff0dSUlrich Drepper { 39325590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 39335590ff0dSUlrich Drepper return -EINVAL; 39345590ff0dSUlrich Drepper 39355590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 39365590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 39375590ff0dSUlrich Drepper 39385590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 39395590ff0dSUlrich Drepper } 39405590ff0dSUlrich Drepper 39413480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 39425590ff0dSUlrich Drepper { 39435590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 39445590ff0dSUlrich Drepper } 39455590ff0dSUlrich Drepper 3946db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 39471da177e4SLinus Torvalds { 3948a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 39491da177e4SLinus Torvalds 39501da177e4SLinus Torvalds if (error) 39511da177e4SLinus Torvalds return error; 39521da177e4SLinus Torvalds 3953acfa4380SAl Viro if (!dir->i_op->symlink) 39541da177e4SLinus Torvalds return -EPERM; 39551da177e4SLinus Torvalds 39561da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 39571da177e4SLinus Torvalds if (error) 39581da177e4SLinus Torvalds return error; 39591da177e4SLinus Torvalds 39601da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3961a74574aaSStephen Smalley if (!error) 3962f38aa942SAmy Griffis fsnotify_create(dir, dentry); 39631da177e4SLinus Torvalds return error; 39641da177e4SLinus Torvalds } 39654d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 39661da177e4SLinus Torvalds 39672e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 39682e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 39691da177e4SLinus Torvalds { 39702ad94ae6SAl Viro int error; 397191a27b2aSJeff Layton struct filename *from; 39726902d925SDave Hansen struct dentry *dentry; 3973dae6ad8fSAl Viro struct path path; 3974f46d3567SJeff Layton unsigned int lookup_flags = 0; 39751da177e4SLinus Torvalds 39761da177e4SLinus Torvalds from = getname(oldname); 39771da177e4SLinus Torvalds if (IS_ERR(from)) 39781da177e4SLinus Torvalds return PTR_ERR(from); 3979f46d3567SJeff Layton retry: 3980f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 39811da177e4SLinus Torvalds error = PTR_ERR(dentry); 39826902d925SDave Hansen if (IS_ERR(dentry)) 3983dae6ad8fSAl Viro goto out_putname; 39846902d925SDave Hansen 398591a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3986a8104a9fSAl Viro if (!error) 398791a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3988921a1650SAl Viro done_path_create(&path, dentry); 3989f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 3990f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 3991f46d3567SJeff Layton goto retry; 3992f46d3567SJeff Layton } 39936902d925SDave Hansen out_putname: 39941da177e4SLinus Torvalds putname(from); 39951da177e4SLinus Torvalds return error; 39961da177e4SLinus Torvalds } 39971da177e4SLinus Torvalds 39983480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 39995590ff0dSUlrich Drepper { 40005590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 40015590ff0dSUlrich Drepper } 40025590ff0dSUlrich Drepper 4003146a8595SJ. Bruce Fields /** 4004146a8595SJ. Bruce Fields * vfs_link - create a new link 4005146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4006146a8595SJ. Bruce Fields * @dir: new parent 4007146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4008146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4009146a8595SJ. Bruce Fields * 4010146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4011146a8595SJ. Bruce Fields * 4012146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4013146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4014146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4015146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4016146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4017146a8595SJ. Bruce Fields * 4018146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4019146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4020146a8595SJ. Bruce Fields * to be NFS exported. 4021146a8595SJ. Bruce Fields */ 4022146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 40231da177e4SLinus Torvalds { 40241da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 40258de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 40261da177e4SLinus Torvalds int error; 40271da177e4SLinus Torvalds 40281da177e4SLinus Torvalds if (!inode) 40291da177e4SLinus Torvalds return -ENOENT; 40301da177e4SLinus Torvalds 4031a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 40321da177e4SLinus Torvalds if (error) 40331da177e4SLinus Torvalds return error; 40341da177e4SLinus Torvalds 40351da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 40361da177e4SLinus Torvalds return -EXDEV; 40371da177e4SLinus Torvalds 40381da177e4SLinus Torvalds /* 40391da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 40401da177e4SLinus Torvalds */ 40411da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 40421da177e4SLinus Torvalds return -EPERM; 4043acfa4380SAl Viro if (!dir->i_op->link) 40441da177e4SLinus Torvalds return -EPERM; 40457e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 40461da177e4SLinus Torvalds return -EPERM; 40471da177e4SLinus Torvalds 40481da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 40491da177e4SLinus Torvalds if (error) 40501da177e4SLinus Torvalds return error; 40511da177e4SLinus Torvalds 40527e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 4053aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4054f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4055aae8a97dSAneesh Kumar K.V error = -ENOENT; 40568de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 40578de52778SAl Viro error = -EMLINK; 4058146a8595SJ. Bruce Fields else { 4059146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4060146a8595SJ. Bruce Fields if (!error) 40611da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4062146a8595SJ. Bruce Fields } 4063f4e0c30cSAl Viro 4064f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4065f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4066f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4067f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4068f4e0c30cSAl Viro } 40697e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 4070e31e14ecSStephen Smalley if (!error) 40717e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 40721da177e4SLinus Torvalds return error; 40731da177e4SLinus Torvalds } 40744d359507SAl Viro EXPORT_SYMBOL(vfs_link); 40751da177e4SLinus Torvalds 40761da177e4SLinus Torvalds /* 40771da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 40781da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 40791da177e4SLinus Torvalds * newname. --KAB 40801da177e4SLinus Torvalds * 40811da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 40821da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 40831da177e4SLinus Torvalds * and other special files. --ADM 40841da177e4SLinus Torvalds */ 40852e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 40862e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 40871da177e4SLinus Torvalds { 40881da177e4SLinus Torvalds struct dentry *new_dentry; 4089dae6ad8fSAl Viro struct path old_path, new_path; 4090146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 409111a7b371SAneesh Kumar K.V int how = 0; 40921da177e4SLinus Torvalds int error; 40931da177e4SLinus Torvalds 409411a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4095c04030e1SUlrich Drepper return -EINVAL; 409611a7b371SAneesh Kumar K.V /* 4097f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4098f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4099f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 410011a7b371SAneesh Kumar K.V */ 4101f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4102f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4103f0cc6ffbSLinus Torvalds return -ENOENT; 410411a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4105f0cc6ffbSLinus Torvalds } 4106c04030e1SUlrich Drepper 410711a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 410811a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4109442e31caSJeff Layton retry: 411011a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 41111da177e4SLinus Torvalds if (error) 41122ad94ae6SAl Viro return error; 41132ad94ae6SAl Viro 4114442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4115442e31caSJeff Layton (how & LOOKUP_REVAL)); 41161da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 41176902d925SDave Hansen if (IS_ERR(new_dentry)) 4118dae6ad8fSAl Viro goto out; 4119dae6ad8fSAl Viro 4120dae6ad8fSAl Viro error = -EXDEV; 4121dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4122dae6ad8fSAl Viro goto out_dput; 4123800179c9SKees Cook error = may_linkat(&old_path); 4124800179c9SKees Cook if (unlikely(error)) 4125800179c9SKees Cook goto out_dput; 4126dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4127be6d3e56SKentaro Takeda if (error) 4128a8104a9fSAl Viro goto out_dput; 4129146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 413075c3f29dSDave Hansen out_dput: 4131921a1650SAl Viro done_path_create(&new_path, new_dentry); 4132146a8595SJ. Bruce Fields if (delegated_inode) { 4133146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4134d22e6338SOleg Drokin if (!error) { 4135d22e6338SOleg Drokin path_put(&old_path); 4136146a8595SJ. Bruce Fields goto retry; 4137146a8595SJ. Bruce Fields } 4138d22e6338SOleg Drokin } 4139442e31caSJeff Layton if (retry_estale(error, how)) { 4140d22e6338SOleg Drokin path_put(&old_path); 4141442e31caSJeff Layton how |= LOOKUP_REVAL; 4142442e31caSJeff Layton goto retry; 4143442e31caSJeff Layton } 41441da177e4SLinus Torvalds out: 41452d8f3038SAl Viro path_put(&old_path); 41461da177e4SLinus Torvalds 41471da177e4SLinus Torvalds return error; 41481da177e4SLinus Torvalds } 41491da177e4SLinus Torvalds 41503480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 41515590ff0dSUlrich Drepper { 4152c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 41535590ff0dSUlrich Drepper } 41545590ff0dSUlrich Drepper 4155bc27027aSMiklos Szeredi /** 4156bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4157bc27027aSMiklos Szeredi * @old_dir: parent of source 4158bc27027aSMiklos Szeredi * @old_dentry: source 4159bc27027aSMiklos Szeredi * @new_dir: parent of destination 4160bc27027aSMiklos Szeredi * @new_dentry: destination 4161bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4162520c8b16SMiklos Szeredi * @flags: rename flags 4163bc27027aSMiklos Szeredi * 4164bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4165bc27027aSMiklos Szeredi * 4166bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4167bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4168bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4169bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4170bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4171bc27027aSMiklos Szeredi * so. 4172bc27027aSMiklos Szeredi * 4173bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4174bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4175bc27027aSMiklos Szeredi * to be NFS exported. 4176bc27027aSMiklos Szeredi * 41771da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 41781da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 41791da177e4SLinus Torvalds * Problems: 4180d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 41811da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 41821da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4183a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 41841da177e4SLinus Torvalds * story. 41856cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 41866cedba89SJ. Bruce Fields * and source (if it is not a directory). 41871b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 41881da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 41891da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4190a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 41911da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 41921da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 41931da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4194a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 41951da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 41961da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 41971da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4198e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 41991b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 42001da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4201c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 42021da177e4SLinus Torvalds * locking]. 42031da177e4SLinus Torvalds */ 42041da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 42058e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4206520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 42071da177e4SLinus Torvalds { 42081da177e4SLinus Torvalds int error; 4209bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 421059b0df21SEric Paris const unsigned char *old_name; 4211bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4212bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4213da1ce067SMiklos Szeredi bool new_is_dir = false; 4214da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 42151da177e4SLinus Torvalds 4216bc27027aSMiklos Szeredi if (source == target) 42171da177e4SLinus Torvalds return 0; 42181da177e4SLinus Torvalds 42191da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 42201da177e4SLinus Torvalds if (error) 42211da177e4SLinus Torvalds return error; 42221da177e4SLinus Torvalds 4223da1ce067SMiklos Szeredi if (!target) { 4224a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4225da1ce067SMiklos Szeredi } else { 4226da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4227da1ce067SMiklos Szeredi 4228da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 42291da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4230da1ce067SMiklos Szeredi else 4231da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4232da1ce067SMiklos Szeredi } 42331da177e4SLinus Torvalds if (error) 42341da177e4SLinus Torvalds return error; 42351da177e4SLinus Torvalds 42367177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 42371da177e4SLinus Torvalds return -EPERM; 42381da177e4SLinus Torvalds 4239520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4240520c8b16SMiklos Szeredi return -EINVAL; 4241520c8b16SMiklos Szeredi 4242bc27027aSMiklos Szeredi /* 4243bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4244bc27027aSMiklos Szeredi * we'll need to flip '..'. 4245bc27027aSMiklos Szeredi */ 4246da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4247da1ce067SMiklos Szeredi if (is_dir) { 4248bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4249bc27027aSMiklos Szeredi if (error) 4250bc27027aSMiklos Szeredi return error; 4251bc27027aSMiklos Szeredi } 4252da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4253da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4254da1ce067SMiklos Szeredi if (error) 4255da1ce067SMiklos Szeredi return error; 4256da1ce067SMiklos Szeredi } 4257da1ce067SMiklos Szeredi } 42580eeca283SRobert Love 42590b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 42600b3974ebSMiklos Szeredi flags); 4261bc27027aSMiklos Szeredi if (error) 4262bc27027aSMiklos Szeredi return error; 4263bc27027aSMiklos Szeredi 4264bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4265bc27027aSMiklos Szeredi dget(new_dentry); 4266da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4267bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4268bc27027aSMiklos Szeredi else if (target) 4269bc27027aSMiklos Szeredi mutex_lock(&target->i_mutex); 4270bc27027aSMiklos Szeredi 4271bc27027aSMiklos Szeredi error = -EBUSY; 42727af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4273bc27027aSMiklos Szeredi goto out; 4274bc27027aSMiklos Szeredi 4275da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4276bc27027aSMiklos Szeredi error = -EMLINK; 4277da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4278bc27027aSMiklos Szeredi goto out; 4279da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4280da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4281da1ce067SMiklos Szeredi goto out; 4282da1ce067SMiklos Szeredi } 4283da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4284bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4285da1ce067SMiklos Szeredi if (!is_dir) { 4286bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4287bc27027aSMiklos Szeredi if (error) 4288bc27027aSMiklos Szeredi goto out; 4289da1ce067SMiklos Szeredi } 4290da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4291bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4292bc27027aSMiklos Szeredi if (error) 4293bc27027aSMiklos Szeredi goto out; 4294bc27027aSMiklos Szeredi } 42957177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4296520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4297520c8b16SMiklos Szeredi new_dir, new_dentry); 4298520c8b16SMiklos Szeredi } else { 42997177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4300520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4301520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4302520c8b16SMiklos Szeredi } 4303bc27027aSMiklos Szeredi if (error) 4304bc27027aSMiklos Szeredi goto out; 4305bc27027aSMiklos Szeredi 4306da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 43071da177e4SLinus Torvalds if (is_dir) 4308bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4309bc27027aSMiklos Szeredi dont_mount(new_dentry); 43108ed936b5SEric W. Biederman detach_mounts(new_dentry); 4311bc27027aSMiklos Szeredi } 4312da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4313da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4314bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4315da1ce067SMiklos Szeredi else 4316da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4317da1ce067SMiklos Szeredi } 4318bc27027aSMiklos Szeredi out: 4319da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4320bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4321bc27027aSMiklos Szeredi else if (target) 4322bc27027aSMiklos Szeredi mutex_unlock(&target->i_mutex); 4323bc27027aSMiklos Szeredi dput(new_dentry); 4324da1ce067SMiklos Szeredi if (!error) { 4325123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4326da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4327da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4328da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4329da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4330da1ce067SMiklos Szeredi } 4331da1ce067SMiklos Szeredi } 43320eeca283SRobert Love fsnotify_oldname_free(old_name); 43330eeca283SRobert Love 43341da177e4SLinus Torvalds return error; 43351da177e4SLinus Torvalds } 43364d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 43371da177e4SLinus Torvalds 4338520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4339520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 43401da177e4SLinus Torvalds { 43411da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 43421da177e4SLinus Torvalds struct dentry *trap; 4343f5beed75SAl Viro struct path old_path, new_path; 4344f5beed75SAl Viro struct qstr old_last, new_last; 4345f5beed75SAl Viro int old_type, new_type; 43468e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 434791a27b2aSJeff Layton struct filename *from; 434891a27b2aSJeff Layton struct filename *to; 4349f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4350c6a94284SJeff Layton bool should_retry = false; 43512ad94ae6SAl Viro int error; 4352520c8b16SMiklos Szeredi 43530d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4354da1ce067SMiklos Szeredi return -EINVAL; 4355da1ce067SMiklos Szeredi 43560d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 43570d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4358520c8b16SMiklos Szeredi return -EINVAL; 4359520c8b16SMiklos Szeredi 43600d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 43610d7a8555SMiklos Szeredi return -EPERM; 43620d7a8555SMiklos Szeredi 4363f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4364f5beed75SAl Viro target_flags = 0; 4365f5beed75SAl Viro 4366c6a94284SJeff Layton retry: 4367f5beed75SAl Viro from = user_path_parent(olddfd, oldname, 4368f5beed75SAl Viro &old_path, &old_last, &old_type, lookup_flags); 436991a27b2aSJeff Layton if (IS_ERR(from)) { 437091a27b2aSJeff Layton error = PTR_ERR(from); 43711da177e4SLinus Torvalds goto exit; 437291a27b2aSJeff Layton } 43731da177e4SLinus Torvalds 4374f5beed75SAl Viro to = user_path_parent(newdfd, newname, 4375f5beed75SAl Viro &new_path, &new_last, &new_type, lookup_flags); 437691a27b2aSJeff Layton if (IS_ERR(to)) { 437791a27b2aSJeff Layton error = PTR_ERR(to); 43781da177e4SLinus Torvalds goto exit1; 437991a27b2aSJeff Layton } 43801da177e4SLinus Torvalds 43811da177e4SLinus Torvalds error = -EXDEV; 4382f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 43831da177e4SLinus Torvalds goto exit2; 43841da177e4SLinus Torvalds 43851da177e4SLinus Torvalds error = -EBUSY; 4386f5beed75SAl Viro if (old_type != LAST_NORM) 43871da177e4SLinus Torvalds goto exit2; 43881da177e4SLinus Torvalds 43890a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 43900a7c3937SMiklos Szeredi error = -EEXIST; 4391f5beed75SAl Viro if (new_type != LAST_NORM) 43921da177e4SLinus Torvalds goto exit2; 43931da177e4SLinus Torvalds 4394f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4395c30dabfeSJan Kara if (error) 4396c30dabfeSJan Kara goto exit2; 4397c30dabfeSJan Kara 43988e6d782cSJ. Bruce Fields retry_deleg: 4399f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 44001da177e4SLinus Torvalds 4401f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 44021da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 44031da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 44041da177e4SLinus Torvalds goto exit3; 44051da177e4SLinus Torvalds /* source must exist */ 44061da177e4SLinus Torvalds error = -ENOENT; 4407b18825a7SDavid Howells if (d_is_negative(old_dentry)) 44081da177e4SLinus Torvalds goto exit4; 4409f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 44101da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 44111da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 44121da177e4SLinus Torvalds goto exit4; 44130a7c3937SMiklos Szeredi error = -EEXIST; 44140a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 44150a7c3937SMiklos Szeredi goto exit5; 4416da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4417da1ce067SMiklos Szeredi error = -ENOENT; 4418da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4419da1ce067SMiklos Szeredi goto exit5; 4420da1ce067SMiklos Szeredi 4421da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4422da1ce067SMiklos Szeredi error = -ENOTDIR; 4423f5beed75SAl Viro if (new_last.name[new_last.len]) 4424da1ce067SMiklos Szeredi goto exit5; 4425da1ce067SMiklos Szeredi } 4426da1ce067SMiklos Szeredi } 44270a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 44280a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 44290a7c3937SMiklos Szeredi error = -ENOTDIR; 4430f5beed75SAl Viro if (old_last.name[old_last.len]) 44310a7c3937SMiklos Szeredi goto exit5; 4432f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 44330a7c3937SMiklos Szeredi goto exit5; 44340a7c3937SMiklos Szeredi } 44350a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 44360a7c3937SMiklos Szeredi error = -EINVAL; 44370a7c3937SMiklos Szeredi if (old_dentry == trap) 44380a7c3937SMiklos Szeredi goto exit5; 44391da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4440da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 44411da177e4SLinus Torvalds error = -ENOTEMPTY; 44421da177e4SLinus Torvalds if (new_dentry == trap) 44431da177e4SLinus Torvalds goto exit5; 44441da177e4SLinus Torvalds 4445f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4446f5beed75SAl Viro &new_path, new_dentry, flags); 4447be6d3e56SKentaro Takeda if (error) 4448c30dabfeSJan Kara goto exit5; 4449f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4450f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4451520c8b16SMiklos Szeredi &delegated_inode, flags); 44521da177e4SLinus Torvalds exit5: 44531da177e4SLinus Torvalds dput(new_dentry); 44541da177e4SLinus Torvalds exit4: 44551da177e4SLinus Torvalds dput(old_dentry); 44561da177e4SLinus Torvalds exit3: 4457f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 44588e6d782cSJ. Bruce Fields if (delegated_inode) { 44598e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 44608e6d782cSJ. Bruce Fields if (!error) 44618e6d782cSJ. Bruce Fields goto retry_deleg; 44628e6d782cSJ. Bruce Fields } 4463f5beed75SAl Viro mnt_drop_write(old_path.mnt); 44641da177e4SLinus Torvalds exit2: 4465c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4466c6a94284SJeff Layton should_retry = true; 4467f5beed75SAl Viro path_put(&new_path); 44682ad94ae6SAl Viro putname(to); 44691da177e4SLinus Torvalds exit1: 4470f5beed75SAl Viro path_put(&old_path); 44711da177e4SLinus Torvalds putname(from); 4472c6a94284SJeff Layton if (should_retry) { 4473c6a94284SJeff Layton should_retry = false; 4474c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4475c6a94284SJeff Layton goto retry; 4476c6a94284SJeff Layton } 44772ad94ae6SAl Viro exit: 44781da177e4SLinus Torvalds return error; 44791da177e4SLinus Torvalds } 44801da177e4SLinus Torvalds 4481520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4482520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4483520c8b16SMiklos Szeredi { 4484520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4485520c8b16SMiklos Szeredi } 4486520c8b16SMiklos Szeredi 4487a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 44885590ff0dSUlrich Drepper { 4489520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 44905590ff0dSUlrich Drepper } 44915590ff0dSUlrich Drepper 4492787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4493787fb6bcSMiklos Szeredi { 4494787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4495787fb6bcSMiklos Szeredi if (error) 4496787fb6bcSMiklos Szeredi return error; 4497787fb6bcSMiklos Szeredi 4498787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4499787fb6bcSMiklos Szeredi return -EPERM; 4500787fb6bcSMiklos Szeredi 4501787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4502787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4503787fb6bcSMiklos Szeredi } 4504787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4505787fb6bcSMiklos Szeredi 45065d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 45071da177e4SLinus Torvalds { 45085d826c84SAl Viro int len = PTR_ERR(link); 45091da177e4SLinus Torvalds if (IS_ERR(link)) 45101da177e4SLinus Torvalds goto out; 45111da177e4SLinus Torvalds 45121da177e4SLinus Torvalds len = strlen(link); 45131da177e4SLinus Torvalds if (len > (unsigned) buflen) 45141da177e4SLinus Torvalds len = buflen; 45151da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 45161da177e4SLinus Torvalds len = -EFAULT; 45171da177e4SLinus Torvalds out: 45181da177e4SLinus Torvalds return len; 45191da177e4SLinus Torvalds } 45205d826c84SAl Viro EXPORT_SYMBOL(readlink_copy); 45211da177e4SLinus Torvalds 45221da177e4SLinus Torvalds /* 45231da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 45241da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 45251da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 45261da177e4SLinus Torvalds */ 45271da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 45281da177e4SLinus Torvalds { 4529cc314eefSLinus Torvalds void *cookie; 45305f2c4179SAl Viro struct inode *inode = d_inode(dentry); 45315f2c4179SAl Viro const char *link = inode->i_link; 4532694a1764SMarcin Slusarz int res; 4533cc314eefSLinus Torvalds 4534d4dee48bSAl Viro if (!link) { 45355f2c4179SAl Viro link = inode->i_op->follow_link(dentry, &cookie); 4536680baacbSAl Viro if (IS_ERR(link)) 4537680baacbSAl Viro return PTR_ERR(link); 4538d4dee48bSAl Viro } 4539680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 45405f2c4179SAl Viro if (inode->i_op->put_link) 45415f2c4179SAl Viro inode->i_op->put_link(inode, cookie); 4542694a1764SMarcin Slusarz return res; 45431da177e4SLinus Torvalds } 45444d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 45451da177e4SLinus Torvalds 45461da177e4SLinus Torvalds /* get the link contents into pagecache */ 45471da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 45481da177e4SLinus Torvalds { 4549ebd09abbSDuane Griffin char *kaddr; 45501da177e4SLinus Torvalds struct page *page; 45511da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 4552090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 45531da177e4SLinus Torvalds if (IS_ERR(page)) 45546fe6900eSNick Piggin return (char*)page; 45551da177e4SLinus Torvalds *ppage = page; 4556ebd09abbSDuane Griffin kaddr = kmap(page); 4557ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 4558ebd09abbSDuane Griffin return kaddr; 45591da177e4SLinus Torvalds } 45601da177e4SLinus Torvalds 45611da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 45621da177e4SLinus Torvalds { 45631da177e4SLinus Torvalds struct page *page = NULL; 45645d826c84SAl Viro int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); 45651da177e4SLinus Torvalds if (page) { 45661da177e4SLinus Torvalds kunmap(page); 45671da177e4SLinus Torvalds page_cache_release(page); 45681da177e4SLinus Torvalds } 45691da177e4SLinus Torvalds return res; 45701da177e4SLinus Torvalds } 45714d359507SAl Viro EXPORT_SYMBOL(page_readlink); 45721da177e4SLinus Torvalds 45736e77137bSAl Viro const char *page_follow_link_light(struct dentry *dentry, void **cookie) 45741da177e4SLinus Torvalds { 4575cc314eefSLinus Torvalds struct page *page = NULL; 4576680baacbSAl Viro char *res = page_getlink(dentry, &page); 4577680baacbSAl Viro if (!IS_ERR(res)) 4578680baacbSAl Viro *cookie = page; 4579680baacbSAl Viro return res; 45801da177e4SLinus Torvalds } 45814d359507SAl Viro EXPORT_SYMBOL(page_follow_link_light); 45821da177e4SLinus Torvalds 45835f2c4179SAl Viro void page_put_link(struct inode *unused, void *cookie) 45841da177e4SLinus Torvalds { 4585cc314eefSLinus Torvalds struct page *page = cookie; 45861da177e4SLinus Torvalds kunmap(page); 45871da177e4SLinus Torvalds page_cache_release(page); 45881da177e4SLinus Torvalds } 45894d359507SAl Viro EXPORT_SYMBOL(page_put_link); 45901da177e4SLinus Torvalds 459154566b2cSNick Piggin /* 459254566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 459354566b2cSNick Piggin */ 459454566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 45951da177e4SLinus Torvalds { 45961da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 45970adb25d2SKirill Korotaev struct page *page; 4598afddba49SNick Piggin void *fsdata; 4599beb497abSDmitriy Monakhov int err; 46001da177e4SLinus Torvalds char *kaddr; 460154566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 460254566b2cSNick Piggin if (nofs) 460354566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 46041da177e4SLinus Torvalds 46057e53cac4SNeilBrown retry: 4606afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 460754566b2cSNick Piggin flags, &page, &fsdata); 46081da177e4SLinus Torvalds if (err) 4609afddba49SNick Piggin goto fail; 4610afddba49SNick Piggin 4611e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 46121da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 4613e8e3c3d6SCong Wang kunmap_atomic(kaddr); 4614afddba49SNick Piggin 4615afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4616afddba49SNick Piggin page, fsdata); 46171da177e4SLinus Torvalds if (err < 0) 46181da177e4SLinus Torvalds goto fail; 4619afddba49SNick Piggin if (err < len-1) 4620afddba49SNick Piggin goto retry; 4621afddba49SNick Piggin 46221da177e4SLinus Torvalds mark_inode_dirty(inode); 46231da177e4SLinus Torvalds return 0; 46241da177e4SLinus Torvalds fail: 46251da177e4SLinus Torvalds return err; 46261da177e4SLinus Torvalds } 46274d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 46281da177e4SLinus Torvalds 46290adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 46300adb25d2SKirill Korotaev { 46310adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 463254566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 46330adb25d2SKirill Korotaev } 46344d359507SAl Viro EXPORT_SYMBOL(page_symlink); 46350adb25d2SKirill Korotaev 463692e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 46371da177e4SLinus Torvalds .readlink = generic_readlink, 46381da177e4SLinus Torvalds .follow_link = page_follow_link_light, 46391da177e4SLinus Torvalds .put_link = page_put_link, 46401da177e4SLinus Torvalds }; 46411da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4642