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 4951f55a6ecSAl Viro struct nameidata { 4961f55a6ecSAl Viro struct path path; 497caa85634SAl Viro union { 4981f55a6ecSAl Viro struct qstr last; 499caa85634SAl Viro struct path link; 500caa85634SAl Viro }; 5011f55a6ecSAl Viro struct path root; 5021f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 5031f55a6ecSAl Viro unsigned int flags; 5041f55a6ecSAl Viro unsigned seq, m_seq; 5051f55a6ecSAl Viro int last_type; 5061f55a6ecSAl Viro unsigned depth; 5075e53084dSAl Viro struct file *base; 508697fc6caSAl Viro struct saved { 509697fc6caSAl Viro struct path link; 510697fc6caSAl Viro void *cookie; 511697fc6caSAl Viro const char *name; 512697fc6caSAl Viro } stack[MAX_NESTED_LINKS + 1]; 5131f55a6ecSAl Viro }; 5141f55a6ecSAl Viro 51519660af7SAl Viro /* 51631e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 51719660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 51819660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 51919660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 52019660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 52119660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 52219660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 52319660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 52431e6b01fSNick Piggin */ 52531e6b01fSNick Piggin 52631e6b01fSNick Piggin /** 52719660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 52819660af7SAl Viro * @nd: nameidata pathwalk data 52919660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 53039191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 53131e6b01fSNick Piggin * 53219660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 53319660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 53419660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 53531e6b01fSNick Piggin */ 53619660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 53731e6b01fSNick Piggin { 53831e6b01fSNick Piggin struct fs_struct *fs = current->fs; 53931e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 54031e6b01fSNick Piggin 54131e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 542e5c832d5SLinus Torvalds 543e5c832d5SLinus Torvalds /* 54448a066e7SAl Viro * After legitimizing the bastards, terminate_walk() 54548a066e7SAl Viro * will do the right thing for non-RCU mode, and all our 54648a066e7SAl Viro * subsequent exit cases should rcu_read_unlock() 54748a066e7SAl Viro * before returning. Do vfsmount first; if dentry 54848a066e7SAl Viro * can't be legitimized, just set nd->path.dentry to NULL 54948a066e7SAl Viro * and rely on dput(NULL) being a no-op. 550e5c832d5SLinus Torvalds */ 55148a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) 552e5c832d5SLinus Torvalds return -ECHILD; 553e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 55415570086SLinus Torvalds 55548a066e7SAl Viro if (!lockref_get_not_dead(&parent->d_lockref)) { 55648a066e7SAl Viro nd->path.dentry = NULL; 557d870b4a1SAl Viro goto out; 55848a066e7SAl Viro } 55948a066e7SAl Viro 56015570086SLinus Torvalds /* 56115570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 56215570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 56315570086SLinus Torvalds * 56415570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 56515570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 56615570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 56715570086SLinus Torvalds * since we checked the sequence number of the parent after we got 56815570086SLinus Torvalds * the child sequence number. So we know the parent must still 56915570086SLinus Torvalds * be valid if the child sequence number is still valid. 57015570086SLinus Torvalds */ 57119660af7SAl Viro if (!dentry) { 572e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 573e5c832d5SLinus Torvalds goto out; 57419660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 57519660af7SAl Viro } else { 576e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 577e5c832d5SLinus Torvalds goto out; 578e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) 579e5c832d5SLinus Torvalds goto drop_dentry; 58019660af7SAl Viro } 581e5c832d5SLinus Torvalds 582e5c832d5SLinus Torvalds /* 583e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 584e5c832d5SLinus Torvalds * still valid and get it if required. 585e5c832d5SLinus Torvalds */ 586e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 587e5c832d5SLinus Torvalds spin_lock(&fs->lock); 588e5c832d5SLinus Torvalds if (nd->root.mnt != fs->root.mnt || nd->root.dentry != fs->root.dentry) 589e5c832d5SLinus Torvalds goto unlock_and_drop_dentry; 59031e6b01fSNick Piggin path_get(&nd->root); 59131e6b01fSNick Piggin spin_unlock(&fs->lock); 59231e6b01fSNick Piggin } 59331e6b01fSNick Piggin 5948b61e74fSAl Viro rcu_read_unlock(); 59531e6b01fSNick Piggin return 0; 59619660af7SAl Viro 597e5c832d5SLinus Torvalds unlock_and_drop_dentry: 59831e6b01fSNick Piggin spin_unlock(&fs->lock); 599e5c832d5SLinus Torvalds drop_dentry: 6008b61e74fSAl Viro rcu_read_unlock(); 601e5c832d5SLinus Torvalds dput(dentry); 602d0d27277SLinus Torvalds goto drop_root_mnt; 603e5c832d5SLinus Torvalds out: 6048b61e74fSAl Viro rcu_read_unlock(); 605d0d27277SLinus Torvalds drop_root_mnt: 606d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 607d0d27277SLinus Torvalds nd->root.mnt = NULL; 60831e6b01fSNick Piggin return -ECHILD; 60931e6b01fSNick Piggin } 61031e6b01fSNick Piggin 6114ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 61234286d66SNick Piggin { 6134ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 61434286d66SNick Piggin } 61534286d66SNick Piggin 6169f1fafeeSAl Viro /** 6179f1fafeeSAl Viro * complete_walk - successful completion of path walk 6189f1fafeeSAl Viro * @nd: pointer nameidata 61939159de2SJeff Layton * 6209f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 6219f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 6229f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 6239f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 6249f1fafeeSAl Viro * need to drop nd->path. 62539159de2SJeff Layton */ 6269f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 62739159de2SJeff Layton { 62816c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 62939159de2SJeff Layton int status; 63039159de2SJeff Layton 6319f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 6329f1fafeeSAl Viro nd->flags &= ~LOOKUP_RCU; 6339f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6349f1fafeeSAl Viro nd->root.mnt = NULL; 63515570086SLinus Torvalds 63648a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) { 6378b61e74fSAl Viro rcu_read_unlock(); 63848a066e7SAl Viro return -ECHILD; 63948a066e7SAl Viro } 640e5c832d5SLinus Torvalds if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) { 6418b61e74fSAl Viro rcu_read_unlock(); 64248a066e7SAl Viro mntput(nd->path.mnt); 6439f1fafeeSAl Viro return -ECHILD; 6449f1fafeeSAl Viro } 645e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) { 6468b61e74fSAl Viro rcu_read_unlock(); 647e5c832d5SLinus Torvalds dput(dentry); 64848a066e7SAl Viro mntput(nd->path.mnt); 649e5c832d5SLinus Torvalds return -ECHILD; 650e5c832d5SLinus Torvalds } 6518b61e74fSAl Viro rcu_read_unlock(); 6529f1fafeeSAl Viro } 6539f1fafeeSAl Viro 65416c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 65539159de2SJeff Layton return 0; 65639159de2SJeff Layton 657ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 65816c2cd71SAl Viro return 0; 65916c2cd71SAl Viro 660ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 66139159de2SJeff Layton if (status > 0) 66239159de2SJeff Layton return 0; 66339159de2SJeff Layton 66416c2cd71SAl Viro if (!status) 66539159de2SJeff Layton status = -ESTALE; 66616c2cd71SAl Viro 6679f1fafeeSAl Viro path_put(&nd->path); 66839159de2SJeff Layton return status; 66939159de2SJeff Layton } 67039159de2SJeff Layton 6712a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 6722a737871SAl Viro { 673f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 6742a737871SAl Viro } 6752a737871SAl Viro 6767bd88377SAl Viro static __always_inline unsigned set_root_rcu(struct nameidata *nd) 67731e6b01fSNick Piggin { 67831e6b01fSNick Piggin struct fs_struct *fs = current->fs; 6797bd88377SAl Viro unsigned seq, res; 680c28cc364SNick Piggin 681c28cc364SNick Piggin do { 682c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 68331e6b01fSNick Piggin nd->root = fs->root; 6847bd88377SAl Viro res = __read_seqcount_begin(&nd->root.dentry->d_seq); 685c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 6867bd88377SAl Viro return res; 68731e6b01fSNick Piggin } 68831e6b01fSNick Piggin 6891d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 690051d3812SIan Kent { 691051d3812SIan Kent dput(path->dentry); 6924ac91378SJan Blunck if (path->mnt != nd->path.mnt) 693051d3812SIan Kent mntput(path->mnt); 694051d3812SIan Kent } 695051d3812SIan Kent 6967b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 6977b9337aaSNick Piggin struct nameidata *nd) 698051d3812SIan Kent { 69931e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 7004ac91378SJan Blunck dput(nd->path.dentry); 70131e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 7024ac91378SJan Blunck mntput(nd->path.mnt); 7039a229683SHuang Shijie } 70431e6b01fSNick Piggin nd->path.mnt = path->mnt; 7054ac91378SJan Blunck nd->path.dentry = path->dentry; 706051d3812SIan Kent } 707051d3812SIan Kent 708b5fb63c1SChristoph Hellwig /* 709b5fb63c1SChristoph Hellwig * Helper to directly jump to a known parsed path from ->follow_link, 710b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 711b5fb63c1SChristoph Hellwig */ 712b5fb63c1SChristoph Hellwig void nd_jump_link(struct nameidata *nd, struct path *path) 713b5fb63c1SChristoph Hellwig { 714b5fb63c1SChristoph Hellwig path_put(&nd->path); 715b5fb63c1SChristoph Hellwig 716b5fb63c1SChristoph Hellwig nd->path = *path; 717b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 718b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 719b5fb63c1SChristoph Hellwig } 720b5fb63c1SChristoph Hellwig 721574197e0SAl Viro static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) 722574197e0SAl Viro { 723574197e0SAl Viro struct inode *inode = link->dentry->d_inode; 724680baacbSAl Viro if (cookie && inode->i_op->put_link) 725680baacbSAl Viro inode->i_op->put_link(link->dentry, cookie); 726574197e0SAl Viro path_put(link); 727574197e0SAl Viro } 728574197e0SAl Viro 729561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 730561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 731800179c9SKees Cook 732800179c9SKees Cook /** 733800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 734800179c9SKees Cook * @link: The path of the symlink 73555852635SRandy Dunlap * @nd: nameidata pathwalk data 736800179c9SKees Cook * 737800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 738800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 739800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 740800179c9SKees Cook * processes from failing races against path names that may change out 741800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 742800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 743800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 744800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 745800179c9SKees Cook * 746800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 747800179c9SKees Cook */ 748800179c9SKees Cook static inline int may_follow_link(struct path *link, struct nameidata *nd) 749800179c9SKees Cook { 750800179c9SKees Cook const struct inode *inode; 751800179c9SKees Cook const struct inode *parent; 752800179c9SKees Cook 753800179c9SKees Cook if (!sysctl_protected_symlinks) 754800179c9SKees Cook return 0; 755800179c9SKees Cook 756800179c9SKees Cook /* Allowed if owner and follower match. */ 757800179c9SKees Cook inode = link->dentry->d_inode; 75881abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 759800179c9SKees Cook return 0; 760800179c9SKees Cook 761800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 762800179c9SKees Cook parent = nd->path.dentry->d_inode; 763800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 764800179c9SKees Cook return 0; 765800179c9SKees Cook 766800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 76781abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 768800179c9SKees Cook return 0; 769800179c9SKees Cook 770ffd8d101SSasha Levin audit_log_link_denied("follow_link", link); 771800179c9SKees Cook path_put_conditional(link, nd); 772800179c9SKees Cook path_put(&nd->path); 773800179c9SKees Cook return -EACCES; 774800179c9SKees Cook } 775800179c9SKees Cook 776800179c9SKees Cook /** 777800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 778800179c9SKees Cook * @inode: the source inode to hardlink from 779800179c9SKees Cook * 780800179c9SKees Cook * Return false if at least one of the following conditions: 781800179c9SKees Cook * - inode is not a regular file 782800179c9SKees Cook * - inode is setuid 783800179c9SKees Cook * - inode is setgid and group-exec 784800179c9SKees Cook * - access failure for read and write 785800179c9SKees Cook * 786800179c9SKees Cook * Otherwise returns true. 787800179c9SKees Cook */ 788800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 789800179c9SKees Cook { 790800179c9SKees Cook umode_t mode = inode->i_mode; 791800179c9SKees Cook 792800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 793800179c9SKees Cook if (!S_ISREG(mode)) 794800179c9SKees Cook return false; 795800179c9SKees Cook 796800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 797800179c9SKees Cook if (mode & S_ISUID) 798800179c9SKees Cook return false; 799800179c9SKees Cook 800800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 801800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 802800179c9SKees Cook return false; 803800179c9SKees Cook 804800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 805800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 806800179c9SKees Cook return false; 807800179c9SKees Cook 808800179c9SKees Cook return true; 809800179c9SKees Cook } 810800179c9SKees Cook 811800179c9SKees Cook /** 812800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 813800179c9SKees Cook * @link: the source to hardlink from 814800179c9SKees Cook * 815800179c9SKees Cook * Block hardlink when all of: 816800179c9SKees Cook * - sysctl_protected_hardlinks enabled 817800179c9SKees Cook * - fsuid does not match inode 818800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 819800179c9SKees Cook * - not CAP_FOWNER 820800179c9SKees Cook * 821800179c9SKees Cook * Returns 0 if successful, -ve on error. 822800179c9SKees Cook */ 823800179c9SKees Cook static int may_linkat(struct path *link) 824800179c9SKees Cook { 825800179c9SKees Cook const struct cred *cred; 826800179c9SKees Cook struct inode *inode; 827800179c9SKees Cook 828800179c9SKees Cook if (!sysctl_protected_hardlinks) 829800179c9SKees Cook return 0; 830800179c9SKees Cook 831800179c9SKees Cook cred = current_cred(); 832800179c9SKees Cook inode = link->dentry->d_inode; 833800179c9SKees Cook 834800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 835800179c9SKees Cook * otherwise, it must be a safe source. 836800179c9SKees Cook */ 83781abe27bSEric W. Biederman if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || 838800179c9SKees Cook capable(CAP_FOWNER)) 839800179c9SKees Cook return 0; 840800179c9SKees Cook 841a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 842800179c9SKees Cook return -EPERM; 843800179c9SKees Cook } 844800179c9SKees Cook 8450a959df5SAl Viro static __always_inline const char * 8460a959df5SAl Viro get_link(struct path *link, struct nameidata *nd, void **p) 8471da177e4SLinus Torvalds { 8487b9337aaSNick Piggin struct dentry *dentry = link->dentry; 8490a959df5SAl Viro struct inode *inode = dentry->d_inode; 8506d7b5aaeSAl Viro int error; 8510a959df5SAl Viro const char *res; 8521da177e4SLinus Torvalds 853844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 854844a3917SAl Viro 8550e794589SAl Viro if (link->mnt == nd->path.mnt) 8560e794589SAl Viro mntget(link->mnt); 8570e794589SAl Viro 8580a959df5SAl Viro res = ERR_PTR(-ELOOP); 8596d7b5aaeSAl Viro if (unlikely(current->total_link_count >= 40)) 8600a959df5SAl Viro goto out; 8616d7b5aaeSAl Viro 862574197e0SAl Viro cond_resched(); 863574197e0SAl Viro current->total_link_count++; 864574197e0SAl Viro 86568ac1234SAl Viro touch_atime(link); 866cd4e91d3SAl Viro 86737882db0SNeilBrown error = security_inode_follow_link(dentry); 8680a959df5SAl Viro res = ERR_PTR(error); 8696d7b5aaeSAl Viro if (error) 8700a959df5SAl Viro goto out; 87136f3b4f6SAl Viro 87286acdca1SAl Viro nd->last_type = LAST_BIND; 873680baacbSAl Viro *p = NULL; 874d4dee48bSAl Viro res = inode->i_link; 875d4dee48bSAl Viro if (!res) { 8760a959df5SAl Viro res = inode->i_op->follow_link(dentry, p, nd); 8770a959df5SAl Viro if (IS_ERR(res)) { 8780a959df5SAl Viro out: 8790a959df5SAl Viro path_put(&nd->path); 8800a959df5SAl Viro path_put(link); 8810a959df5SAl Viro } 882d4dee48bSAl Viro } 8830a959df5SAl Viro return res; 8840a959df5SAl Viro } 8856d7b5aaeSAl Viro 88631e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 88731e6b01fSNick Piggin { 8880714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 8890714a533SAl Viro struct mount *parent; 89031e6b01fSNick Piggin struct dentry *mountpoint; 89131e6b01fSNick Piggin 8920714a533SAl Viro parent = mnt->mnt_parent; 8930714a533SAl Viro if (&parent->mnt == path->mnt) 89431e6b01fSNick Piggin return 0; 895a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 89631e6b01fSNick Piggin path->dentry = mountpoint; 8970714a533SAl Viro path->mnt = &parent->mnt; 89831e6b01fSNick Piggin return 1; 89931e6b01fSNick Piggin } 90031e6b01fSNick Piggin 901f015f126SDavid Howells /* 902f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 903f015f126SDavid Howells * 904f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 905f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 906f015f126SDavid Howells * Up is towards /. 907f015f126SDavid Howells * 908f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 909f015f126SDavid Howells * root. 910f015f126SDavid Howells */ 911bab77ebfSAl Viro int follow_up(struct path *path) 9121da177e4SLinus Torvalds { 9130714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9140714a533SAl Viro struct mount *parent; 9151da177e4SLinus Torvalds struct dentry *mountpoint; 91699b7db7bSNick Piggin 91748a066e7SAl Viro read_seqlock_excl(&mount_lock); 9180714a533SAl Viro parent = mnt->mnt_parent; 9193c0a6163SAl Viro if (parent == mnt) { 92048a066e7SAl Viro read_sequnlock_excl(&mount_lock); 9211da177e4SLinus Torvalds return 0; 9221da177e4SLinus Torvalds } 9230714a533SAl Viro mntget(&parent->mnt); 924a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 92548a066e7SAl Viro read_sequnlock_excl(&mount_lock); 926bab77ebfSAl Viro dput(path->dentry); 927bab77ebfSAl Viro path->dentry = mountpoint; 928bab77ebfSAl Viro mntput(path->mnt); 9290714a533SAl Viro path->mnt = &parent->mnt; 9301da177e4SLinus Torvalds return 1; 9311da177e4SLinus Torvalds } 9324d359507SAl Viro EXPORT_SYMBOL(follow_up); 9331da177e4SLinus Torvalds 934b5c84bf6SNick Piggin /* 9359875cf80SDavid Howells * Perform an automount 9369875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 9379875cf80SDavid Howells * were called with. 9381da177e4SLinus Torvalds */ 9399875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 9409875cf80SDavid Howells bool *need_mntput) 94131e6b01fSNick Piggin { 9429875cf80SDavid Howells struct vfsmount *mnt; 943ea5b778aSDavid Howells int err; 9449875cf80SDavid Howells 9459875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 9469875cf80SDavid Howells return -EREMOTE; 9479875cf80SDavid Howells 9480ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 9490ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 9500ec26fd0SMiklos Szeredi * the name. 9510ec26fd0SMiklos Szeredi * 9520ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 9535a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 9540ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 9550ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 9560ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 9570ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 9585a30d8a2SDavid Howells */ 9595a30d8a2SDavid Howells if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 960d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 9615a30d8a2SDavid Howells path->dentry->d_inode) 9629875cf80SDavid Howells return -EISDIR; 9630ec26fd0SMiklos Szeredi 9649875cf80SDavid Howells current->total_link_count++; 9659875cf80SDavid Howells if (current->total_link_count >= 40) 9669875cf80SDavid Howells return -ELOOP; 9679875cf80SDavid Howells 9689875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 9699875cf80SDavid Howells if (IS_ERR(mnt)) { 9709875cf80SDavid Howells /* 9719875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 9729875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 9739875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 9749875cf80SDavid Howells * 9759875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 9769875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 9779875cf80SDavid Howells * the path is inaccessible and we should say so. 9789875cf80SDavid Howells */ 97949084c3bSAl Viro if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) 9809875cf80SDavid Howells return -EREMOTE; 9819875cf80SDavid Howells return PTR_ERR(mnt); 98231e6b01fSNick Piggin } 983ea5b778aSDavid Howells 9849875cf80SDavid Howells if (!mnt) /* mount collision */ 9859875cf80SDavid Howells return 0; 9869875cf80SDavid Howells 9878aef1884SAl Viro if (!*need_mntput) { 9888aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 9898aef1884SAl Viro mntget(path->mnt); 9908aef1884SAl Viro *need_mntput = true; 9918aef1884SAl Viro } 99219a167afSAl Viro err = finish_automount(mnt, path); 993ea5b778aSDavid Howells 994ea5b778aSDavid Howells switch (err) { 995ea5b778aSDavid Howells case -EBUSY: 996ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 99719a167afSAl Viro return 0; 998ea5b778aSDavid Howells case 0: 9998aef1884SAl Viro path_put(path); 10009875cf80SDavid Howells path->mnt = mnt; 10019875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 10029875cf80SDavid Howells return 0; 100319a167afSAl Viro default: 100419a167afSAl Viro return err; 10059875cf80SDavid Howells } 100619a167afSAl Viro 1007ea5b778aSDavid Howells } 10089875cf80SDavid Howells 10099875cf80SDavid Howells /* 10109875cf80SDavid Howells * Handle a dentry that is managed in some way. 1011cc53ce53SDavid Howells * - Flagged for transit management (autofs) 10129875cf80SDavid Howells * - Flagged as mountpoint 10139875cf80SDavid Howells * - Flagged as automount point 10149875cf80SDavid Howells * 10159875cf80SDavid Howells * This may only be called in refwalk mode. 10169875cf80SDavid Howells * 10179875cf80SDavid Howells * Serialization is taken care of in namespace.c 10189875cf80SDavid Howells */ 10199875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 10209875cf80SDavid Howells { 10218aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 10229875cf80SDavid Howells unsigned managed; 10239875cf80SDavid Howells bool need_mntput = false; 10248aef1884SAl Viro int ret = 0; 10259875cf80SDavid Howells 10269875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 10279875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 10289875cf80SDavid Howells * the components of that value change under us */ 10299875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 10309875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 10319875cf80SDavid Howells unlikely(managed != 0)) { 1032cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1033cc53ce53SDavid Howells * being held. */ 1034cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1035cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1036cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 10371aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1038cc53ce53SDavid Howells if (ret < 0) 10398aef1884SAl Viro break; 1040cc53ce53SDavid Howells } 1041cc53ce53SDavid Howells 10429875cf80SDavid Howells /* Transit to a mounted filesystem. */ 10439875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 10449875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10459875cf80SDavid Howells if (mounted) { 10469875cf80SDavid Howells dput(path->dentry); 10479875cf80SDavid Howells if (need_mntput) 1048463ffb2eSAl Viro mntput(path->mnt); 1049463ffb2eSAl Viro path->mnt = mounted; 1050463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 10519875cf80SDavid Howells need_mntput = true; 10529875cf80SDavid Howells continue; 1053463ffb2eSAl Viro } 1054463ffb2eSAl Viro 10559875cf80SDavid Howells /* Something is mounted on this dentry in another 10569875cf80SDavid Howells * namespace and/or whatever was mounted there in this 105748a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 105848a066e7SAl Viro * get it */ 10591da177e4SLinus Torvalds } 10609875cf80SDavid Howells 10619875cf80SDavid Howells /* Handle an automount point */ 10629875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 10639875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 10649875cf80SDavid Howells if (ret < 0) 10658aef1884SAl Viro break; 10669875cf80SDavid Howells continue; 10679875cf80SDavid Howells } 10689875cf80SDavid Howells 10699875cf80SDavid Howells /* We didn't change the current path point */ 10709875cf80SDavid Howells break; 10719875cf80SDavid Howells } 10728aef1884SAl Viro 10738aef1884SAl Viro if (need_mntput && path->mnt == mnt) 10748aef1884SAl Viro mntput(path->mnt); 10758aef1884SAl Viro if (ret == -EISDIR) 10768aef1884SAl Viro ret = 0; 1077a3fbbde7SAl Viro return ret < 0 ? ret : need_mntput; 10781da177e4SLinus Torvalds } 10791da177e4SLinus Torvalds 1080cc53ce53SDavid Howells int follow_down_one(struct path *path) 10811da177e4SLinus Torvalds { 10821da177e4SLinus Torvalds struct vfsmount *mounted; 10831da177e4SLinus Torvalds 10841c755af4SAl Viro mounted = lookup_mnt(path); 10851da177e4SLinus Torvalds if (mounted) { 10869393bd07SAl Viro dput(path->dentry); 10879393bd07SAl Viro mntput(path->mnt); 10889393bd07SAl Viro path->mnt = mounted; 10899393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 10901da177e4SLinus Torvalds return 1; 10911da177e4SLinus Torvalds } 10921da177e4SLinus Torvalds return 0; 10931da177e4SLinus Torvalds } 10944d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 10951da177e4SLinus Torvalds 1096b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 109762a7375eSIan Kent { 1098b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1099b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 110062a7375eSIan Kent } 110162a7375eSIan Kent 11029875cf80SDavid Howells /* 1103287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1104287548e4SAl Viro * we meet a managed dentry that would need blocking. 11059875cf80SDavid Howells */ 11069875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1107287548e4SAl Viro struct inode **inode) 11089875cf80SDavid Howells { 110962a7375eSIan Kent for (;;) { 1110c7105365SAl Viro struct mount *mounted; 111162a7375eSIan Kent /* 111262a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 111362a7375eSIan Kent * that wants to block transit. 111462a7375eSIan Kent */ 1115b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1116b8faf035SNeilBrown case -ECHILD: 1117b8faf035SNeilBrown default: 1118ab90911fSDavid Howells return false; 1119b8faf035SNeilBrown case -EISDIR: 1120b8faf035SNeilBrown return true; 1121b8faf035SNeilBrown case 0: 1122b8faf035SNeilBrown break; 1123b8faf035SNeilBrown } 112462a7375eSIan Kent 112562a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1126b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 112762a7375eSIan Kent 1128474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 11299875cf80SDavid Howells if (!mounted) 11309875cf80SDavid Howells break; 1131c7105365SAl Viro path->mnt = &mounted->mnt; 1132c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1133a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 11349875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 113559430262SLinus Torvalds /* 113659430262SLinus Torvalds * Update the inode too. We don't need to re-check the 113759430262SLinus Torvalds * dentry sequence number here after this d_inode read, 113859430262SLinus Torvalds * because a mount-point is always pinned. 113959430262SLinus Torvalds */ 114059430262SLinus Torvalds *inode = path->dentry->d_inode; 11419875cf80SDavid Howells } 1142f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1143b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1144287548e4SAl Viro } 1145287548e4SAl Viro 114631e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 114731e6b01fSNick Piggin { 11484023bfc9SAl Viro struct inode *inode = nd->inode; 11497bd88377SAl Viro if (!nd->root.mnt) 115031e6b01fSNick Piggin set_root_rcu(nd); 115131e6b01fSNick Piggin 115231e6b01fSNick Piggin while (1) { 115331e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 115431e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 115531e6b01fSNick Piggin break; 115631e6b01fSNick Piggin } 115731e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 115831e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 115931e6b01fSNick Piggin struct dentry *parent = old->d_parent; 116031e6b01fSNick Piggin unsigned seq; 116131e6b01fSNick Piggin 11624023bfc9SAl Viro inode = parent->d_inode; 116331e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 116431e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1165ef7562d5SAl Viro goto failed; 116631e6b01fSNick Piggin nd->path.dentry = parent; 116731e6b01fSNick Piggin nd->seq = seq; 116831e6b01fSNick Piggin break; 116931e6b01fSNick Piggin } 117031e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 117131e6b01fSNick Piggin break; 11724023bfc9SAl Viro inode = nd->path.dentry->d_inode; 117331e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 117431e6b01fSNick Piggin } 1175b37199e6SAl Viro while (d_mountpoint(nd->path.dentry)) { 1176b37199e6SAl Viro struct mount *mounted; 1177b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1178b37199e6SAl Viro if (!mounted) 1179b37199e6SAl Viro break; 1180b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1181b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 11824023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1183b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1184f5be3e29SAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1185b37199e6SAl Viro goto failed; 1186b37199e6SAl Viro } 11874023bfc9SAl Viro nd->inode = inode; 118831e6b01fSNick Piggin return 0; 1189ef7562d5SAl Viro 1190ef7562d5SAl Viro failed: 1191ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 11925b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1193ef7562d5SAl Viro nd->root.mnt = NULL; 11948b61e74fSAl Viro rcu_read_unlock(); 1195ef7562d5SAl Viro return -ECHILD; 119631e6b01fSNick Piggin } 119731e6b01fSNick Piggin 11989875cf80SDavid Howells /* 1199cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1200cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1201cc53ce53SDavid Howells * caller is permitted to proceed or not. 1202cc53ce53SDavid Howells */ 12037cc90cc3SAl Viro int follow_down(struct path *path) 1204cc53ce53SDavid Howells { 1205cc53ce53SDavid Howells unsigned managed; 1206cc53ce53SDavid Howells int ret; 1207cc53ce53SDavid Howells 1208cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1209cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1210cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1211cc53ce53SDavid Howells * being held. 1212cc53ce53SDavid Howells * 1213cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1214cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1215cc53ce53SDavid Howells * other than its daemon the right to mount on its 1216cc53ce53SDavid Howells * superstructure. 1217cc53ce53SDavid Howells * 1218cc53ce53SDavid Howells * The filesystem may sleep at this point. 1219cc53ce53SDavid Howells */ 1220cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1221cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1222cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1223ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 12241aed3e42SAl Viro path->dentry, false); 1225cc53ce53SDavid Howells if (ret < 0) 1226cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1227cc53ce53SDavid Howells } 1228cc53ce53SDavid Howells 1229cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1230cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1231cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1232cc53ce53SDavid Howells if (!mounted) 1233cc53ce53SDavid Howells break; 1234cc53ce53SDavid Howells dput(path->dentry); 1235cc53ce53SDavid Howells mntput(path->mnt); 1236cc53ce53SDavid Howells path->mnt = mounted; 1237cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1238cc53ce53SDavid Howells continue; 1239cc53ce53SDavid Howells } 1240cc53ce53SDavid Howells 1241cc53ce53SDavid Howells /* Don't handle automount points here */ 1242cc53ce53SDavid Howells break; 1243cc53ce53SDavid Howells } 1244cc53ce53SDavid Howells return 0; 1245cc53ce53SDavid Howells } 12464d359507SAl Viro EXPORT_SYMBOL(follow_down); 1247cc53ce53SDavid Howells 1248cc53ce53SDavid Howells /* 12499875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 12509875cf80SDavid Howells */ 12519875cf80SDavid Howells static void follow_mount(struct path *path) 12529875cf80SDavid Howells { 12539875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 12549875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12559875cf80SDavid Howells if (!mounted) 12569875cf80SDavid Howells break; 12579875cf80SDavid Howells dput(path->dentry); 12589875cf80SDavid Howells mntput(path->mnt); 12599875cf80SDavid Howells path->mnt = mounted; 12609875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 12619875cf80SDavid Howells } 12629875cf80SDavid Howells } 12639875cf80SDavid Howells 126431e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 12651da177e4SLinus Torvalds { 12667bd88377SAl Viro if (!nd->root.mnt) 12672a737871SAl Viro set_root(nd); 1268e518ddb7SAndreas Mohr 12691da177e4SLinus Torvalds while(1) { 12704ac91378SJan Blunck struct dentry *old = nd->path.dentry; 12711da177e4SLinus Torvalds 12722a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 12732a737871SAl Viro nd->path.mnt == nd->root.mnt) { 12741da177e4SLinus Torvalds break; 12751da177e4SLinus Torvalds } 12764ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 12773088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 12783088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 12791da177e4SLinus Torvalds dput(old); 12801da177e4SLinus Torvalds break; 12811da177e4SLinus Torvalds } 12823088dd70SAl Viro if (!follow_up(&nd->path)) 12831da177e4SLinus Torvalds break; 12841da177e4SLinus Torvalds } 128579ed0226SAl Viro follow_mount(&nd->path); 128631e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 12871da177e4SLinus Torvalds } 12881da177e4SLinus Torvalds 12891da177e4SLinus Torvalds /* 1290bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1291bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1292bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1293bad61189SMiklos Szeredi * 1294bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1295baa03890SNick Piggin */ 1296bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1297201f956eSAl Viro unsigned int flags, bool *need_lookup) 1298baa03890SNick Piggin { 1299baa03890SNick Piggin struct dentry *dentry; 1300bad61189SMiklos Szeredi int error; 1301baa03890SNick Piggin 1302bad61189SMiklos Szeredi *need_lookup = false; 1303bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1304bad61189SMiklos Szeredi if (dentry) { 130539e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1306201f956eSAl Viro error = d_revalidate(dentry, flags); 1307bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1308bad61189SMiklos Szeredi if (error < 0) { 1309bad61189SMiklos Szeredi dput(dentry); 1310bad61189SMiklos Szeredi return ERR_PTR(error); 13115542aa2fSEric W. Biederman } else { 13125542aa2fSEric W. Biederman d_invalidate(dentry); 1313bad61189SMiklos Szeredi dput(dentry); 1314bad61189SMiklos Szeredi dentry = NULL; 1315bad61189SMiklos Szeredi } 1316bad61189SMiklos Szeredi } 1317bad61189SMiklos Szeredi } 1318bad61189SMiklos Szeredi } 1319baa03890SNick Piggin 1320bad61189SMiklos Szeredi if (!dentry) { 1321bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1322baa03890SNick Piggin if (unlikely(!dentry)) 1323baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1324baa03890SNick Piggin 1325bad61189SMiklos Szeredi *need_lookup = true; 1326baa03890SNick Piggin } 1327baa03890SNick Piggin return dentry; 1328baa03890SNick Piggin } 1329baa03890SNick Piggin 1330baa03890SNick Piggin /* 133113a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 133213a2c3beSJ. Bruce Fields * unhashed. 1333bad61189SMiklos Szeredi * 1334bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 133544396f4bSJosef Bacik */ 1336bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 133772bd866aSAl Viro unsigned int flags) 133844396f4bSJosef Bacik { 133944396f4bSJosef Bacik struct dentry *old; 134044396f4bSJosef Bacik 134144396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1342bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1343e188dc02SMiklos Szeredi dput(dentry); 134444396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1345e188dc02SMiklos Szeredi } 134644396f4bSJosef Bacik 134772bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 134844396f4bSJosef Bacik if (unlikely(old)) { 134944396f4bSJosef Bacik dput(dentry); 135044396f4bSJosef Bacik dentry = old; 135144396f4bSJosef Bacik } 135244396f4bSJosef Bacik return dentry; 135344396f4bSJosef Bacik } 135444396f4bSJosef Bacik 1355a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 135672bd866aSAl Viro struct dentry *base, unsigned int flags) 1357a3255546SAl Viro { 1358bad61189SMiklos Szeredi bool need_lookup; 1359a3255546SAl Viro struct dentry *dentry; 1360a3255546SAl Viro 136172bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1362bad61189SMiklos Szeredi if (!need_lookup) 1363a3255546SAl Viro return dentry; 1364bad61189SMiklos Szeredi 136572bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1366a3255546SAl Viro } 1367a3255546SAl Viro 136844396f4bSJosef Bacik /* 13691da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 13701da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 13711da177e4SLinus Torvalds * It _is_ time-critical. 13721da177e4SLinus Torvalds */ 1373e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 137431e6b01fSNick Piggin struct path *path, struct inode **inode) 13751da177e4SLinus Torvalds { 13764ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 137731e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 13785a18fff2SAl Viro int need_reval = 1; 13795a18fff2SAl Viro int status = 1; 13809875cf80SDavid Howells int err; 13819875cf80SDavid Howells 13823cac260aSAl Viro /* 1383b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1384b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1385b04f784eSNick Piggin * do the non-racy lookup, below. 1386b04f784eSNick Piggin */ 138731e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 138831e6b01fSNick Piggin unsigned seq; 1389766c4cbfSAl Viro bool negative; 1390da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 13915a18fff2SAl Viro if (!dentry) 13925a18fff2SAl Viro goto unlazy; 13935a18fff2SAl Viro 139412f8ad4bSLinus Torvalds /* 139512f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 139612f8ad4bSLinus Torvalds * the dentry name information from lookup. 139712f8ad4bSLinus Torvalds */ 139812f8ad4bSLinus Torvalds *inode = dentry->d_inode; 1399766c4cbfSAl Viro negative = d_is_negative(dentry); 140012f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 140112f8ad4bSLinus Torvalds return -ECHILD; 1402766c4cbfSAl Viro if (negative) 1403766c4cbfSAl Viro return -ENOENT; 140412f8ad4bSLinus Torvalds 140512f8ad4bSLinus Torvalds /* 140612f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 140712f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 140812f8ad4bSLinus Torvalds * 140912f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 141012f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 141112f8ad4bSLinus Torvalds */ 141231e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 141331e6b01fSNick Piggin return -ECHILD; 141431e6b01fSNick Piggin nd->seq = seq; 14155a18fff2SAl Viro 141624643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 14174ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14185a18fff2SAl Viro if (unlikely(status <= 0)) { 14195a18fff2SAl Viro if (status != -ECHILD) 14205a18fff2SAl Viro need_reval = 0; 14215a18fff2SAl Viro goto unlazy; 14225a18fff2SAl Viro } 142324643087SAl Viro } 142431e6b01fSNick Piggin path->mnt = mnt; 142531e6b01fSNick Piggin path->dentry = dentry; 1426b8faf035SNeilBrown if (likely(__follow_mount_rcu(nd, path, inode))) 14279875cf80SDavid Howells return 0; 14285a18fff2SAl Viro unlazy: 142919660af7SAl Viro if (unlazy_walk(nd, dentry)) 14305a18fff2SAl Viro return -ECHILD; 14315a18fff2SAl Viro } else { 1432e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 143324643087SAl Viro } 14345a18fff2SAl Viro 143581e6f520SAl Viro if (unlikely(!dentry)) 143681e6f520SAl Viro goto need_lookup; 14375a18fff2SAl Viro 14385a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 14394ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14405a18fff2SAl Viro if (unlikely(status <= 0)) { 14415a18fff2SAl Viro if (status < 0) { 14425a18fff2SAl Viro dput(dentry); 14435a18fff2SAl Viro return status; 14445a18fff2SAl Viro } 14455542aa2fSEric W. Biederman d_invalidate(dentry); 14465a18fff2SAl Viro dput(dentry); 144781e6f520SAl Viro goto need_lookup; 14485a18fff2SAl Viro } 1449697f514dSMiklos Szeredi 1450766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1451766c4cbfSAl Viro dput(dentry); 1452766c4cbfSAl Viro return -ENOENT; 1453766c4cbfSAl Viro } 14541da177e4SLinus Torvalds path->mnt = mnt; 14551da177e4SLinus Torvalds path->dentry = dentry; 14569875cf80SDavid Howells err = follow_managed(path, nd->flags); 145789312214SIan Kent if (unlikely(err < 0)) { 145889312214SIan Kent path_put_conditional(path, nd); 14599875cf80SDavid Howells return err; 146089312214SIan Kent } 1461a3fbbde7SAl Viro if (err) 1462a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 146331e6b01fSNick Piggin *inode = path->dentry->d_inode; 14641da177e4SLinus Torvalds return 0; 146581e6f520SAl Viro 146681e6f520SAl Viro need_lookup: 1467697f514dSMiklos Szeredi return 1; 1468697f514dSMiklos Szeredi } 1469697f514dSMiklos Szeredi 1470697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1471cc2a5271SAl Viro static int lookup_slow(struct nameidata *nd, struct path *path) 1472697f514dSMiklos Szeredi { 1473697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1474697f514dSMiklos Szeredi int err; 1475697f514dSMiklos Szeredi 1476697f514dSMiklos Szeredi parent = nd->path.dentry; 147781e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 147881e6f520SAl Viro 147981e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 1480cc2a5271SAl Viro dentry = __lookup_hash(&nd->last, parent, nd->flags); 148181e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 148281e6f520SAl Viro if (IS_ERR(dentry)) 148381e6f520SAl Viro return PTR_ERR(dentry); 1484697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1485697f514dSMiklos Szeredi path->dentry = dentry; 1486697f514dSMiklos Szeredi err = follow_managed(path, nd->flags); 1487697f514dSMiklos Szeredi if (unlikely(err < 0)) { 1488697f514dSMiklos Szeredi path_put_conditional(path, nd); 1489697f514dSMiklos Szeredi return err; 1490697f514dSMiklos Szeredi } 1491697f514dSMiklos Szeredi if (err) 1492697f514dSMiklos Szeredi nd->flags |= LOOKUP_JUMPED; 1493697f514dSMiklos Szeredi return 0; 14941da177e4SLinus Torvalds } 14951da177e4SLinus Torvalds 149652094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 149752094c8aSAl Viro { 149852094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 14994ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 150052094c8aSAl Viro if (err != -ECHILD) 150152094c8aSAl Viro return err; 150219660af7SAl Viro if (unlazy_walk(nd, NULL)) 150352094c8aSAl Viro return -ECHILD; 150452094c8aSAl Viro } 15054ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 150652094c8aSAl Viro } 150752094c8aSAl Viro 15089856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 15099856fa1bSAl Viro { 15109856fa1bSAl Viro if (type == LAST_DOTDOT) { 15119856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 15129856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 15139856fa1bSAl Viro return -ECHILD; 15149856fa1bSAl Viro } else 15159856fa1bSAl Viro follow_dotdot(nd); 15169856fa1bSAl Viro } 15179856fa1bSAl Viro return 0; 15189856fa1bSAl Viro } 15199856fa1bSAl Viro 1520951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1521951361f9SAl Viro { 1522951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1523951361f9SAl Viro path_put(&nd->path); 1524951361f9SAl Viro } else { 1525951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 15265b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1527951361f9SAl Viro nd->root.mnt = NULL; 15288b61e74fSAl Viro rcu_read_unlock(); 1529951361f9SAl Viro } 1530951361f9SAl Viro } 1531951361f9SAl Viro 15323ddcd056SLinus Torvalds /* 15333ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 15343ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 15353ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 15363ddcd056SLinus Torvalds * for the common case. 15373ddcd056SLinus Torvalds */ 1538b18825a7SDavid Howells static inline int should_follow_link(struct dentry *dentry, int follow) 15393ddcd056SLinus Torvalds { 1540b18825a7SDavid Howells return unlikely(d_is_symlink(dentry)) ? follow : 0; 15413ddcd056SLinus Torvalds } 15423ddcd056SLinus Torvalds 1543caa85634SAl Viro static int walk_component(struct nameidata *nd, int follow) 1544ce57dfc1SAl Viro { 1545caa85634SAl Viro struct path path; 1546ce57dfc1SAl Viro struct inode *inode; 1547ce57dfc1SAl Viro int err; 1548ce57dfc1SAl Viro /* 1549ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1550ce57dfc1SAl Viro * to be able to know about the current root directory and 1551ce57dfc1SAl Viro * parent relationships. 1552ce57dfc1SAl Viro */ 155321b9b073SAl Viro if (unlikely(nd->last_type != LAST_NORM)) 155421b9b073SAl Viro return handle_dots(nd, nd->last_type); 1555caa85634SAl Viro err = lookup_fast(nd, &path, &inode); 1556ce57dfc1SAl Viro if (unlikely(err)) { 1557697f514dSMiklos Szeredi if (err < 0) 1558697f514dSMiklos Szeredi goto out_err; 1559697f514dSMiklos Szeredi 1560caa85634SAl Viro err = lookup_slow(nd, &path); 1561697f514dSMiklos Szeredi if (err < 0) 1562697f514dSMiklos Szeredi goto out_err; 1563697f514dSMiklos Szeredi 1564caa85634SAl Viro inode = path.dentry->d_inode; 1565697f514dSMiklos Szeredi err = -ENOENT; 1566caa85634SAl Viro if (d_is_negative(path.dentry)) 1567697f514dSMiklos Szeredi goto out_path_put; 1568766c4cbfSAl Viro } 1569697f514dSMiklos Szeredi 1570caa85634SAl Viro if (should_follow_link(path.dentry, follow)) { 157119660af7SAl Viro if (nd->flags & LOOKUP_RCU) { 1572caa85634SAl Viro if (unlikely(nd->path.mnt != path.mnt || 1573caa85634SAl Viro unlazy_walk(nd, path.dentry))) { 1574697f514dSMiklos Szeredi err = -ECHILD; 1575697f514dSMiklos Szeredi goto out_err; 157619660af7SAl Viro } 157719660af7SAl Viro } 1578caa85634SAl Viro BUG_ON(inode != path.dentry->d_inode); 1579caa85634SAl Viro nd->link = path; 1580ce57dfc1SAl Viro return 1; 1581ce57dfc1SAl Viro } 1582caa85634SAl Viro path_to_nameidata(&path, nd); 1583ce57dfc1SAl Viro nd->inode = inode; 1584ce57dfc1SAl Viro return 0; 1585697f514dSMiklos Szeredi 1586697f514dSMiklos Szeredi out_path_put: 1587caa85634SAl Viro path_to_nameidata(&path, nd); 1588697f514dSMiklos Szeredi out_err: 1589697f514dSMiklos Szeredi terminate_walk(nd); 1590697f514dSMiklos Szeredi return err; 1591ce57dfc1SAl Viro } 1592ce57dfc1SAl Viro 15931da177e4SLinus Torvalds /* 1594bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1595bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1596bfcfaa77SLinus Torvalds * 1597bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1598bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1599bfcfaa77SLinus Torvalds * fast. 1600bfcfaa77SLinus Torvalds * 1601bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1602bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1603bfcfaa77SLinus Torvalds * crossing operation. 1604bfcfaa77SLinus Torvalds * 1605bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1606bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1607bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1608bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1609bfcfaa77SLinus Torvalds */ 1610bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1611bfcfaa77SLinus Torvalds 1612f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1613bfcfaa77SLinus Torvalds 1614f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1615bfcfaa77SLinus Torvalds 1616bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1617bfcfaa77SLinus Torvalds { 161899d263d4SLinus Torvalds return hash_64(hash, 32); 1619bfcfaa77SLinus Torvalds } 1620bfcfaa77SLinus Torvalds 1621bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1622bfcfaa77SLinus Torvalds 1623bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1624bfcfaa77SLinus Torvalds 1625bfcfaa77SLinus Torvalds #endif 1626bfcfaa77SLinus Torvalds 1627bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1628bfcfaa77SLinus Torvalds { 1629bfcfaa77SLinus Torvalds unsigned long a, mask; 1630bfcfaa77SLinus Torvalds unsigned long hash = 0; 1631bfcfaa77SLinus Torvalds 1632bfcfaa77SLinus Torvalds for (;;) { 1633e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1634bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1635bfcfaa77SLinus Torvalds break; 1636bfcfaa77SLinus Torvalds hash += a; 1637f132c5beSAl Viro hash *= 9; 1638bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1639bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1640bfcfaa77SLinus Torvalds if (!len) 1641bfcfaa77SLinus Torvalds goto done; 1642bfcfaa77SLinus Torvalds } 1643a5c21dceSWill Deacon mask = bytemask_from_count(len); 1644bfcfaa77SLinus Torvalds hash += mask & a; 1645bfcfaa77SLinus Torvalds done: 1646bfcfaa77SLinus Torvalds return fold_hash(hash); 1647bfcfaa77SLinus Torvalds } 1648bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1649bfcfaa77SLinus Torvalds 1650bfcfaa77SLinus Torvalds /* 1651bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1652d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1653bfcfaa77SLinus Torvalds */ 1654d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1655bfcfaa77SLinus Torvalds { 165636126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 165736126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1658bfcfaa77SLinus Torvalds 1659bfcfaa77SLinus Torvalds hash = a = 0; 1660bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1661bfcfaa77SLinus Torvalds do { 1662bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1663bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1664e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 166536126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 166636126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1667bfcfaa77SLinus Torvalds 166836126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 166936126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 167036126f8fSLinus Torvalds 167136126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 167236126f8fSLinus Torvalds 167336126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 16749226b5b4SLinus Torvalds len += find_zero(mask); 1675d6bb3e90SLinus Torvalds return hashlen_create(fold_hash(hash), len); 1676bfcfaa77SLinus Torvalds } 1677bfcfaa77SLinus Torvalds 1678bfcfaa77SLinus Torvalds #else 1679bfcfaa77SLinus Torvalds 16800145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 16810145acc2SLinus Torvalds { 16820145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 16830145acc2SLinus Torvalds while (len--) 16840145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 16850145acc2SLinus Torvalds return end_name_hash(hash); 16860145acc2SLinus Torvalds } 1687ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 16880145acc2SLinus Torvalds 16893ddcd056SLinus Torvalds /* 1690200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1691200e9ef7SLinus Torvalds * one character. 1692200e9ef7SLinus Torvalds */ 1693d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1694200e9ef7SLinus Torvalds { 1695200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1696200e9ef7SLinus Torvalds unsigned long len = 0, c; 1697200e9ef7SLinus Torvalds 1698200e9ef7SLinus Torvalds c = (unsigned char)*name; 1699200e9ef7SLinus Torvalds do { 1700200e9ef7SLinus Torvalds len++; 1701200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1702200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1703200e9ef7SLinus Torvalds } while (c && c != '/'); 1704d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 1705200e9ef7SLinus Torvalds } 1706200e9ef7SLinus Torvalds 1707bfcfaa77SLinus Torvalds #endif 1708bfcfaa77SLinus Torvalds 1709200e9ef7SLinus Torvalds /* 17101da177e4SLinus Torvalds * Name resolution. 1711ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1712ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 17131da177e4SLinus Torvalds * 1714ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1715ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 17161da177e4SLinus Torvalds */ 17176de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 17181da177e4SLinus Torvalds { 1719697fc6caSAl Viro struct saved *last = nd->stack; 17201da177e4SLinus Torvalds int err; 17211da177e4SLinus Torvalds 17221da177e4SLinus Torvalds while (*name=='/') 17231da177e4SLinus Torvalds name++; 17241da177e4SLinus Torvalds if (!*name) 17259e18f10aSAl Viro return 0; 17261da177e4SLinus Torvalds 17271da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 17281da177e4SLinus Torvalds for(;;) { 1729d6bb3e90SLinus Torvalds u64 hash_len; 1730fe479a58SAl Viro int type; 17311da177e4SLinus Torvalds 173252094c8aSAl Viro err = may_lookup(nd); 17331da177e4SLinus Torvalds if (err) 17341da177e4SLinus Torvalds break; 17351da177e4SLinus Torvalds 1736d6bb3e90SLinus Torvalds hash_len = hash_name(name); 17371da177e4SLinus Torvalds 1738fe479a58SAl Viro type = LAST_NORM; 1739d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 1740fe479a58SAl Viro case 2: 1741200e9ef7SLinus Torvalds if (name[1] == '.') { 1742fe479a58SAl Viro type = LAST_DOTDOT; 174316c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 174416c2cd71SAl Viro } 1745fe479a58SAl Viro break; 1746fe479a58SAl Viro case 1: 1747fe479a58SAl Viro type = LAST_DOT; 1748fe479a58SAl Viro } 17495a202bcdSAl Viro if (likely(type == LAST_NORM)) { 17505a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 175116c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 17525a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 1753a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 1754da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 17555a202bcdSAl Viro if (err < 0) 17565a202bcdSAl Viro break; 1757d6bb3e90SLinus Torvalds hash_len = this.hash_len; 1758d6bb3e90SLinus Torvalds name = this.name; 17595a202bcdSAl Viro } 17605a202bcdSAl Viro } 1761fe479a58SAl Viro 1762d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 1763d6bb3e90SLinus Torvalds nd->last.name = name; 17645f4a6a69SAl Viro nd->last_type = type; 17655f4a6a69SAl Viro 1766d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 1767d6bb3e90SLinus Torvalds if (!*name) 1768bdf6cbf1SAl Viro goto OK; 1769200e9ef7SLinus Torvalds /* 1770200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1771200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1772200e9ef7SLinus Torvalds */ 1773200e9ef7SLinus Torvalds do { 1774d6bb3e90SLinus Torvalds name++; 1775d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 1776d6bb3e90SLinus Torvalds if (!*name) 1777bdf6cbf1SAl Viro goto OK; 17785f4a6a69SAl Viro 1779caa85634SAl Viro err = walk_component(nd, LOOKUP_FOLLOW); 1780bb8603f8SAl Viro Walked: 1781ce57dfc1SAl Viro if (err < 0) 1782bdf6cbf1SAl Viro goto Err; 1783fe479a58SAl Viro 1784ce57dfc1SAl Viro if (err) { 1785d40bcc09SAl Viro const char *s; 1786d40bcc09SAl Viro 17875a460275SAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 17885a460275SAl Viro path_put_conditional(&nd->link, nd); 17895a460275SAl Viro path_put(&nd->path); 1790bdf6cbf1SAl Viro err = -ELOOP; 1791bdf6cbf1SAl Viro goto Err; 17925a460275SAl Viro } 17935a460275SAl Viro BUG_ON(nd->depth >= MAX_NESTED_LINKS); 17945a460275SAl Viro 17955a460275SAl Viro nd->depth++; 17965a460275SAl Viro current->link_count++; 179732cd7468SAl Viro last++; 17985a460275SAl Viro 179932cd7468SAl Viro last->link = nd->link; 180032cd7468SAl Viro s = get_link(&last->link, nd, &last->cookie); 18015a460275SAl Viro 1802172a39a0SAl Viro if (unlikely(IS_ERR(s))) { 1803172a39a0SAl Viro err = PTR_ERR(s); 1804b0c24c3bSAl Viro current->link_count--; 1805b0c24c3bSAl Viro nd->depth--; 180632cd7468SAl Viro last--; 1807bdf6cbf1SAl Viro goto Err; 1808172a39a0SAl Viro } 1809172a39a0SAl Viro err = 0; 181012b09578SAl Viro if (unlikely(!s)) { 181112b09578SAl Viro /* jumped */ 181232cd7468SAl Viro put_link(nd, &last->link, last->cookie); 181348c8b0c5SAl Viro current->link_count--; 181448c8b0c5SAl Viro nd->depth--; 181532cd7468SAl Viro last--; 181612b09578SAl Viro } else { 1817172a39a0SAl Viro if (*s == '/') { 1818172a39a0SAl Viro if (!nd->root.mnt) 1819172a39a0SAl Viro set_root(nd); 1820172a39a0SAl Viro path_put(&nd->path); 1821172a39a0SAl Viro nd->path = nd->root; 1822172a39a0SAl Viro path_get(&nd->root); 1823172a39a0SAl Viro nd->flags |= LOOKUP_JUMPED; 18249e18f10aSAl Viro while (unlikely(*++s == '/')) 18259e18f10aSAl Viro ; 1826172a39a0SAl Viro } 1827172a39a0SAl Viro nd->inode = nd->path.dentry->d_inode; 182832cd7468SAl Viro last->name = name; 18299e18f10aSAl Viro if (!*s) 18309e18f10aSAl Viro goto OK; 183132cd7468SAl Viro name = s; 18329e18f10aSAl Viro continue; 183348c8b0c5SAl Viro } 183431e6b01fSNick Piggin } 183544b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 18363ddcd056SLinus Torvalds err = -ENOTDIR; 18373ddcd056SLinus Torvalds break; 18385f4a6a69SAl Viro } 1839ce57dfc1SAl Viro } 1840951361f9SAl Viro terminate_walk(nd); 1841bdf6cbf1SAl Viro Err: 184207681481SAl Viro while (unlikely(nd->depth)) { 184307681481SAl Viro put_link(nd, &last->link, last->cookie); 184407681481SAl Viro current->link_count--; 184507681481SAl Viro nd->depth--; 184607681481SAl Viro last--; 184707681481SAl Viro } 18481da177e4SLinus Torvalds return err; 1849bdf6cbf1SAl Viro OK: 185007681481SAl Viro if (unlikely(nd->depth)) { 185107681481SAl Viro name = last->name; 185207681481SAl Viro err = walk_component(nd, LOOKUP_FOLLOW); 185307681481SAl Viro put_link(nd, &last->link, last->cookie); 185407681481SAl Viro current->link_count--; 185507681481SAl Viro nd->depth--; 185607681481SAl Viro last--; 185707681481SAl Viro goto Walked; 185807681481SAl Viro } 1859bdf6cbf1SAl Viro return 0; 18601da177e4SLinus Torvalds } 18611da177e4SLinus Torvalds 18626e8a1f87SAl Viro static int path_init(int dfd, const struct filename *name, unsigned int flags, 18635e53084dSAl Viro struct nameidata *nd) 186431e6b01fSNick Piggin { 186531e6b01fSNick Piggin int retval = 0; 1866fd2f7cb5SAl Viro const char *s = name->name; 186731e6b01fSNick Piggin 186831e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 1869980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 187031e6b01fSNick Piggin nd->depth = 0; 18715e53084dSAl Viro nd->base = NULL; 18725b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 1873b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 1874b18825a7SDavid Howells struct inode *inode = root->d_inode; 1875fd2f7cb5SAl Viro if (*s) { 187644b1d530SMiklos Szeredi if (!d_can_lookup(root)) 18775b6ca027SAl Viro return -ENOTDIR; 18785b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 18795b6ca027SAl Viro if (retval) 18805b6ca027SAl Viro return retval; 188173d049a4SAl Viro } 18825b6ca027SAl Viro nd->path = nd->root; 18835b6ca027SAl Viro nd->inode = inode; 18845b6ca027SAl Viro if (flags & LOOKUP_RCU) { 18858b61e74fSAl Viro rcu_read_lock(); 18865b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 188748a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 18885b6ca027SAl Viro } else { 18895b6ca027SAl Viro path_get(&nd->path); 18905b6ca027SAl Viro } 1891d465887fSAl Viro goto done; 18925b6ca027SAl Viro } 18935b6ca027SAl Viro 189431e6b01fSNick Piggin nd->root.mnt = NULL; 189531e6b01fSNick Piggin 189648a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 1897fd2f7cb5SAl Viro if (*s == '/') { 1898e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 18998b61e74fSAl Viro rcu_read_lock(); 19007bd88377SAl Viro nd->seq = set_root_rcu(nd); 1901e41f7d4eSAl Viro } else { 1902e41f7d4eSAl Viro set_root(nd); 1903e41f7d4eSAl Viro path_get(&nd->root); 1904e41f7d4eSAl Viro } 190531e6b01fSNick Piggin nd->path = nd->root; 190631e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1907e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 190831e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1909c28cc364SNick Piggin unsigned seq; 191031e6b01fSNick Piggin 19118b61e74fSAl Viro rcu_read_lock(); 191231e6b01fSNick Piggin 1913c28cc364SNick Piggin do { 1914c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 191531e6b01fSNick Piggin nd->path = fs->pwd; 1916c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1917c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1918e41f7d4eSAl Viro } else { 1919e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1920e41f7d4eSAl Viro } 192131e6b01fSNick Piggin } else { 1922582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 19232903ff01SAl Viro struct fd f = fdget_raw(dfd); 192431e6b01fSNick Piggin struct dentry *dentry; 192531e6b01fSNick Piggin 19262903ff01SAl Viro if (!f.file) 19272903ff01SAl Viro return -EBADF; 192831e6b01fSNick Piggin 19292903ff01SAl Viro dentry = f.file->f_path.dentry; 193031e6b01fSNick Piggin 1931fd2f7cb5SAl Viro if (*s) { 193244b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 19332903ff01SAl Viro fdput(f); 19342903ff01SAl Viro return -ENOTDIR; 1935f52e0c11SAl Viro } 19362903ff01SAl Viro } 19372903ff01SAl Viro 19382903ff01SAl Viro nd->path = f.file->f_path; 1939e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 19409c225f26SLinus Torvalds if (f.flags & FDPUT_FPUT) 19415e53084dSAl Viro nd->base = f.file; 1942c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 19438b61e74fSAl Viro rcu_read_lock(); 19445590ff0dSUlrich Drepper } else { 19452903ff01SAl Viro path_get(&nd->path); 19462903ff01SAl Viro fdput(f); 19471da177e4SLinus Torvalds } 1948e41f7d4eSAl Viro } 1949e41f7d4eSAl Viro 195031e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 19514023bfc9SAl Viro if (!(flags & LOOKUP_RCU)) 1952d465887fSAl Viro goto done; 19534023bfc9SAl Viro if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) 1954d465887fSAl Viro goto done; 19554023bfc9SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 19564023bfc9SAl Viro nd->root.mnt = NULL; 19574023bfc9SAl Viro rcu_read_unlock(); 19584023bfc9SAl Viro return -ECHILD; 1959d465887fSAl Viro done: 1960d465887fSAl Viro current->total_link_count = 0; 1961fd2f7cb5SAl Viro return link_path_walk(s, nd); 19629b4a9b14SAl Viro } 19639b4a9b14SAl Viro 1964893b7775SAl Viro static void path_cleanup(struct nameidata *nd) 1965893b7775SAl Viro { 1966893b7775SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 1967893b7775SAl Viro path_put(&nd->root); 1968893b7775SAl Viro nd->root.mnt = NULL; 1969893b7775SAl Viro } 1970893b7775SAl Viro if (unlikely(nd->base)) 1971893b7775SAl Viro fput(nd->base); 19729b4a9b14SAl Viro } 19739b4a9b14SAl Viro 197495fa25d9SAl Viro static int trailing_symlink(struct path *link, struct nameidata *nd, void **p) 197595fa25d9SAl Viro { 197695fa25d9SAl Viro const char *s; 197795fa25d9SAl Viro int error = may_follow_link(link, nd); 197895fa25d9SAl Viro if (unlikely(error)) 197995fa25d9SAl Viro return error; 198095fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 198195fa25d9SAl Viro s = get_link(link, nd, p); 198295fa25d9SAl Viro if (unlikely(IS_ERR(s))) 198395fa25d9SAl Viro return PTR_ERR(s); 198495fa25d9SAl Viro if (unlikely(!s)) 198595fa25d9SAl Viro return 0; 198695fa25d9SAl Viro if (*s == '/') { 198795fa25d9SAl Viro if (!nd->root.mnt) 198895fa25d9SAl Viro set_root(nd); 198995fa25d9SAl Viro path_put(&nd->path); 199095fa25d9SAl Viro nd->path = nd->root; 199195fa25d9SAl Viro path_get(&nd->root); 199295fa25d9SAl Viro nd->flags |= LOOKUP_JUMPED; 199395fa25d9SAl Viro } 199495fa25d9SAl Viro nd->inode = nd->path.dentry->d_inode; 199595fa25d9SAl Viro error = link_path_walk(s, nd); 199695fa25d9SAl Viro if (unlikely(error)) 199795fa25d9SAl Viro put_link(nd, link, *p); 199895fa25d9SAl Viro return error; 199995fa25d9SAl Viro } 200095fa25d9SAl Viro 2001caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2002bd92d7feSAl Viro { 2003bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2004bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2005bd92d7feSAl Viro 2006bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 2007caa85634SAl Viro return walk_component(nd, nd->flags & LOOKUP_FOLLOW); 2008bd92d7feSAl Viro } 2009bd92d7feSAl Viro 20109b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 20115eb6b495SAl Viro static int path_lookupat(int dfd, const struct filename *name, 20129b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 20139b4a9b14SAl Viro { 2014bd92d7feSAl Viro int err; 201531e6b01fSNick Piggin 201631e6b01fSNick Piggin /* 201731e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 201831e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 201931e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 202031e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 202131e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 202231e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 202331e6b01fSNick Piggin * analogue, foo_rcu(). 202431e6b01fSNick Piggin * 202531e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 202631e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 202731e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 202831e6b01fSNick Piggin * be able to complete). 202931e6b01fSNick Piggin */ 20306e8a1f87SAl Viro err = path_init(dfd, name, flags, nd); 2031bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 2032caa85634SAl Viro err = lookup_last(nd); 2033bd92d7feSAl Viro while (err > 0) { 2034697fc6caSAl Viro nd->stack[0].link = nd->link; 2035697fc6caSAl Viro err = trailing_symlink(&nd->stack[0].link, 2036697fc6caSAl Viro nd, &nd->stack[0].cookie); 20376d7b5aaeSAl Viro if (err) 20386d7b5aaeSAl Viro break; 2039caa85634SAl Viro err = lookup_last(nd); 2040697fc6caSAl Viro put_link(nd, &nd->stack[0].link, nd->stack[0].cookie); 2041bd92d7feSAl Viro } 2042bd92d7feSAl Viro } 2043ee0827cdSAl Viro 20449f1fafeeSAl Viro if (!err) 20459f1fafeeSAl Viro err = complete_walk(nd); 2046bd92d7feSAl Viro 2047bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 204844b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 2049bd92d7feSAl Viro path_put(&nd->path); 2050bd23a539SAl Viro err = -ENOTDIR; 2051bd92d7feSAl Viro } 2052bd92d7feSAl Viro } 205316c2cd71SAl Viro 2054893b7775SAl Viro path_cleanup(nd); 2055bd92d7feSAl Viro return err; 205631e6b01fSNick Piggin } 205731e6b01fSNick Piggin 2058873f1eedSJeff Layton static int filename_lookup(int dfd, struct filename *name, 2059873f1eedSJeff Layton unsigned int flags, struct nameidata *nd) 2060873f1eedSJeff Layton { 20615eb6b495SAl Viro int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 2062873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 20635eb6b495SAl Viro retval = path_lookupat(dfd, name, flags, nd); 2064873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 20655eb6b495SAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 2066873f1eedSJeff Layton 2067873f1eedSJeff Layton if (likely(!retval)) 2068adb5c247SJeff Layton audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); 2069873f1eedSJeff Layton return retval; 2070873f1eedSJeff Layton } 2071873f1eedSJeff Layton 207279714f72SAl Viro /* does lookup, returns the object with parent locked */ 207379714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 20745590ff0dSUlrich Drepper { 207551689104SPaul Moore struct filename *filename = getname_kernel(name); 207679714f72SAl Viro struct nameidata nd; 207779714f72SAl Viro struct dentry *d; 207851689104SPaul Moore int err; 207951689104SPaul Moore 208051689104SPaul Moore if (IS_ERR(filename)) 208151689104SPaul Moore return ERR_CAST(filename); 208251689104SPaul Moore 208351689104SPaul Moore err = filename_lookup(AT_FDCWD, filename, LOOKUP_PARENT, &nd); 208451689104SPaul Moore if (err) { 208551689104SPaul Moore d = ERR_PTR(err); 208651689104SPaul Moore goto out; 208751689104SPaul Moore } 208879714f72SAl Viro if (nd.last_type != LAST_NORM) { 208979714f72SAl Viro path_put(&nd.path); 209051689104SPaul Moore d = ERR_PTR(-EINVAL); 209151689104SPaul Moore goto out; 209279714f72SAl Viro } 209379714f72SAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 20941e0ea001SAl Viro d = __lookup_hash(&nd.last, nd.path.dentry, 0); 209579714f72SAl Viro if (IS_ERR(d)) { 209679714f72SAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 209779714f72SAl Viro path_put(&nd.path); 209851689104SPaul Moore goto out; 209979714f72SAl Viro } 210079714f72SAl Viro *path = nd.path; 210151689104SPaul Moore out: 210251689104SPaul Moore putname(filename); 210379714f72SAl Viro return d; 21045590ff0dSUlrich Drepper } 21055590ff0dSUlrich Drepper 2106d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2107d1811465SAl Viro { 2108d1811465SAl Viro struct nameidata nd; 210974eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 211074eb8cc5SAl Viro int res = PTR_ERR(filename); 211174eb8cc5SAl Viro 211274eb8cc5SAl Viro if (!IS_ERR(filename)) { 211374eb8cc5SAl Viro res = filename_lookup(AT_FDCWD, filename, flags, &nd); 211474eb8cc5SAl Viro putname(filename); 2115d1811465SAl Viro if (!res) 2116d1811465SAl Viro *path = nd.path; 211774eb8cc5SAl Viro } 2118d1811465SAl Viro return res; 2119d1811465SAl Viro } 21204d359507SAl Viro EXPORT_SYMBOL(kern_path); 2121d1811465SAl Viro 212216f18200SJosef 'Jeff' Sipek /** 212316f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 212416f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 212516f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 212616f18200SJosef 'Jeff' Sipek * @name: pointer to file name 212716f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2128e0a01249SAl Viro * @path: pointer to struct path to fill 212916f18200SJosef 'Jeff' Sipek */ 213016f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 213116f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2132e0a01249SAl Viro struct path *path) 213316f18200SJosef 'Jeff' Sipek { 213474eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 213574eb8cc5SAl Viro int err = PTR_ERR(filename); 213674eb8cc5SAl Viro 213774eb8cc5SAl Viro BUG_ON(flags & LOOKUP_PARENT); 213874eb8cc5SAl Viro 213974eb8cc5SAl Viro /* the first argument of filename_lookup() is ignored with LOOKUP_ROOT */ 214074eb8cc5SAl Viro if (!IS_ERR(filename)) { 2141e0a01249SAl Viro struct nameidata nd; 2142e0a01249SAl Viro nd.root.dentry = dentry; 2143e0a01249SAl Viro nd.root.mnt = mnt; 214474eb8cc5SAl Viro err = filename_lookup(AT_FDCWD, filename, 214574eb8cc5SAl Viro flags | LOOKUP_ROOT, &nd); 2146e0a01249SAl Viro if (!err) 2147e0a01249SAl Viro *path = nd.path; 214874eb8cc5SAl Viro putname(filename); 214974eb8cc5SAl Viro } 2150e0a01249SAl Viro return err; 215116f18200SJosef 'Jeff' Sipek } 21524d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 215316f18200SJosef 'Jeff' Sipek 2154eead1911SChristoph Hellwig /** 2155a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2156eead1911SChristoph Hellwig * @name: pathname component to lookup 2157eead1911SChristoph Hellwig * @base: base directory to lookup from 2158eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2159eead1911SChristoph Hellwig * 2160a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 21619e7543e9SAl Viro * not be called by generic code. 2162eead1911SChristoph Hellwig */ 2163057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2164057f6c01SJames Morris { 2165057f6c01SJames Morris struct qstr this; 21666a96ba54SAl Viro unsigned int c; 2167cda309deSMiklos Szeredi int err; 2168057f6c01SJames Morris 21692f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 21702f9092e1SDavid Woodhouse 21716a96ba54SAl Viro this.name = name; 21726a96ba54SAl Viro this.len = len; 21730145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 21746a96ba54SAl Viro if (!len) 21756a96ba54SAl Viro return ERR_PTR(-EACCES); 21766a96ba54SAl Viro 217721d8a15aSAl Viro if (unlikely(name[0] == '.')) { 217821d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 217921d8a15aSAl Viro return ERR_PTR(-EACCES); 218021d8a15aSAl Viro } 218121d8a15aSAl Viro 21826a96ba54SAl Viro while (len--) { 21836a96ba54SAl Viro c = *(const unsigned char *)name++; 21846a96ba54SAl Viro if (c == '/' || c == '\0') 21856a96ba54SAl Viro return ERR_PTR(-EACCES); 21866a96ba54SAl Viro } 21875a202bcdSAl Viro /* 21885a202bcdSAl Viro * See if the low-level filesystem might want 21895a202bcdSAl Viro * to use its own hash.. 21905a202bcdSAl Viro */ 21915a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2192da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 21935a202bcdSAl Viro if (err < 0) 21945a202bcdSAl Viro return ERR_PTR(err); 21955a202bcdSAl Viro } 2196eead1911SChristoph Hellwig 2197cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2198cda309deSMiklos Szeredi if (err) 2199cda309deSMiklos Szeredi return ERR_PTR(err); 2200cda309deSMiklos Szeredi 220172bd866aSAl Viro return __lookup_hash(&this, base, 0); 2202057f6c01SJames Morris } 22034d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2204057f6c01SJames Morris 22051fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 22061fa1e7f6SAndy Whitcroft struct path *path, int *empty) 22071da177e4SLinus Torvalds { 22082d8f3038SAl Viro struct nameidata nd; 220991a27b2aSJeff Layton struct filename *tmp = getname_flags(name, flags, empty); 22101da177e4SLinus Torvalds int err = PTR_ERR(tmp); 22111da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 22122d8f3038SAl Viro 22132d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 22142d8f3038SAl Viro 2215873f1eedSJeff Layton err = filename_lookup(dfd, tmp, flags, &nd); 22161da177e4SLinus Torvalds putname(tmp); 22172d8f3038SAl Viro if (!err) 22182d8f3038SAl Viro *path = nd.path; 22191da177e4SLinus Torvalds } 22201da177e4SLinus Torvalds return err; 22211da177e4SLinus Torvalds } 22221da177e4SLinus Torvalds 22231fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 22241fa1e7f6SAndy Whitcroft struct path *path) 22251fa1e7f6SAndy Whitcroft { 2226f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 22271fa1e7f6SAndy Whitcroft } 22284d359507SAl Viro EXPORT_SYMBOL(user_path_at); 22291fa1e7f6SAndy Whitcroft 2230873f1eedSJeff Layton /* 2231873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2232873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2233873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2234873f1eedSJeff Layton * path-walking is complete. 2235873f1eedSJeff Layton */ 223691a27b2aSJeff Layton static struct filename * 2237f5beed75SAl Viro user_path_parent(int dfd, const char __user *path, 2238f5beed75SAl Viro struct path *parent, 2239f5beed75SAl Viro struct qstr *last, 2240f5beed75SAl Viro int *type, 22419e790bd6SJeff Layton unsigned int flags) 22422ad94ae6SAl Viro { 2243f5beed75SAl Viro struct nameidata nd; 224491a27b2aSJeff Layton struct filename *s = getname(path); 22452ad94ae6SAl Viro int error; 22462ad94ae6SAl Viro 22479e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 22489e790bd6SJeff Layton flags &= LOOKUP_REVAL; 22499e790bd6SJeff Layton 22502ad94ae6SAl Viro if (IS_ERR(s)) 225191a27b2aSJeff Layton return s; 22522ad94ae6SAl Viro 2253f5beed75SAl Viro error = filename_lookup(dfd, s, flags | LOOKUP_PARENT, &nd); 225491a27b2aSJeff Layton if (error) { 22552ad94ae6SAl Viro putname(s); 225691a27b2aSJeff Layton return ERR_PTR(error); 225791a27b2aSJeff Layton } 2258f5beed75SAl Viro *parent = nd.path; 2259f5beed75SAl Viro *last = nd.last; 2260f5beed75SAl Viro *type = nd.last_type; 22612ad94ae6SAl Viro 226291a27b2aSJeff Layton return s; 22632ad94ae6SAl Viro } 22642ad94ae6SAl Viro 22658033426eSJeff Layton /** 2266197df04cSAl Viro * mountpoint_last - look up last component for umount 22678033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 22688033426eSJeff Layton * @path: pointer to container for result 22698033426eSJeff Layton * 22708033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 22718033426eSJeff Layton * need to resolve the path without doing any revalidation. 22728033426eSJeff Layton * 22738033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 22748033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 22758033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 22768033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 22778033426eSJeff Layton * bogus and it doesn't exist. 22788033426eSJeff Layton * 22798033426eSJeff Layton * Returns: 22808033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 22818033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 22828033426eSJeff Layton * put in this case. 22838033426eSJeff Layton * 22848033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 22858033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 22868033426eSJeff Layton * The nd->path reference will also be put. 22878033426eSJeff Layton * 22888033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 22898033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 22908033426eSJeff Layton * to the link, and nd->path will *not* be put. 22918033426eSJeff Layton */ 22928033426eSJeff Layton static int 2293197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 22948033426eSJeff Layton { 22958033426eSJeff Layton int error = 0; 22968033426eSJeff Layton struct dentry *dentry; 22978033426eSJeff Layton struct dentry *dir = nd->path.dentry; 22988033426eSJeff Layton 229935759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 230035759521SAl Viro if (nd->flags & LOOKUP_RCU) { 230135759521SAl Viro if (unlazy_walk(nd, NULL)) { 23028033426eSJeff Layton error = -ECHILD; 230335759521SAl Viro goto out; 230435759521SAl Viro } 23058033426eSJeff Layton } 23068033426eSJeff Layton 23078033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 23088033426eSJeff Layton 23098033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 23108033426eSJeff Layton error = handle_dots(nd, nd->last_type); 231135759521SAl Viro if (error) 231235759521SAl Viro goto out; 23138033426eSJeff Layton dentry = dget(nd->path.dentry); 231435759521SAl Viro goto done; 23158033426eSJeff Layton } 23168033426eSJeff Layton 23178033426eSJeff Layton mutex_lock(&dir->d_inode->i_mutex); 23188033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 23198033426eSJeff Layton if (!dentry) { 23208033426eSJeff Layton /* 23218033426eSJeff Layton * No cached dentry. Mounted dentries are pinned in the cache, 23228033426eSJeff Layton * so that means that this dentry is probably a symlink or the 23238033426eSJeff Layton * path doesn't actually point to a mounted dentry. 23248033426eSJeff Layton */ 23258033426eSJeff Layton dentry = d_alloc(dir, &nd->last); 23268033426eSJeff Layton if (!dentry) { 23278033426eSJeff Layton error = -ENOMEM; 2328bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 232935759521SAl Viro goto out; 23308033426eSJeff Layton } 233135759521SAl Viro dentry = lookup_real(dir->d_inode, dentry, nd->flags); 233235759521SAl Viro error = PTR_ERR(dentry); 2333bcceeebaSDave Jones if (IS_ERR(dentry)) { 2334bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 233535759521SAl Viro goto out; 23368033426eSJeff Layton } 2337bcceeebaSDave Jones } 23388033426eSJeff Layton mutex_unlock(&dir->d_inode->i_mutex); 23398033426eSJeff Layton 234035759521SAl Viro done: 2341698934dfSDavid Howells if (d_is_negative(dentry)) { 23428033426eSJeff Layton error = -ENOENT; 23438033426eSJeff Layton dput(dentry); 234435759521SAl Viro goto out; 234535759521SAl Viro } 23468033426eSJeff Layton path->dentry = dentry; 2347295dc39dSVasily Averin path->mnt = nd->path.mnt; 2348caa85634SAl Viro if (should_follow_link(dentry, nd->flags & LOOKUP_FOLLOW)) { 2349caa85634SAl Viro nd->link = *path; 23508033426eSJeff Layton return 1; 2351caa85634SAl Viro } 2352295dc39dSVasily Averin mntget(path->mnt); 23538033426eSJeff Layton follow_mount(path); 235435759521SAl Viro error = 0; 235535759521SAl Viro out: 23568033426eSJeff Layton terminate_walk(nd); 23578033426eSJeff Layton return error; 23588033426eSJeff Layton } 23598033426eSJeff Layton 23608033426eSJeff Layton /** 2361197df04cSAl Viro * path_mountpoint - look up a path to be umounted 23628033426eSJeff Layton * @dfd: directory file descriptor to start walk from 23638033426eSJeff Layton * @name: full pathname to walk 2364606d6fe3SRandy Dunlap * @path: pointer to container for result 23658033426eSJeff Layton * @flags: lookup flags 23668033426eSJeff Layton * 23678033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2368606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 23698033426eSJeff Layton */ 23708033426eSJeff Layton static int 2371668696dcSAl Viro path_mountpoint(int dfd, const struct filename *name, struct path *path, 237246afd6f6SAl Viro struct nameidata *nd, unsigned int flags) 23738033426eSJeff Layton { 237446afd6f6SAl Viro int err = path_init(dfd, name, flags, nd); 23758033426eSJeff Layton if (unlikely(err)) 2376115cbfdcSAl Viro goto out; 23778033426eSJeff Layton 237846afd6f6SAl Viro err = mountpoint_last(nd, path); 23798033426eSJeff Layton while (err > 0) { 2380697fc6caSAl Viro nd->stack[0].link = nd->link; 2381697fc6caSAl Viro err = trailing_symlink(&nd->stack[0].link, 2382697fc6caSAl Viro nd, &nd->stack[0].cookie); 23838033426eSJeff Layton if (err) 23848033426eSJeff Layton break; 238546afd6f6SAl Viro err = mountpoint_last(nd, path); 2386697fc6caSAl Viro put_link(nd, &nd->stack[0].link, nd->stack[0].cookie); 23878033426eSJeff Layton } 23888033426eSJeff Layton out: 238946afd6f6SAl Viro path_cleanup(nd); 23908033426eSJeff Layton return err; 23918033426eSJeff Layton } 23928033426eSJeff Layton 23932d864651SAl Viro static int 2394668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 23952d864651SAl Viro unsigned int flags) 23962d864651SAl Viro { 239746afd6f6SAl Viro struct nameidata nd; 2398cbaab2dbSAl Viro int error; 2399668696dcSAl Viro if (IS_ERR(name)) 2400668696dcSAl Viro return PTR_ERR(name); 240146afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_RCU); 24022d864651SAl Viro if (unlikely(error == -ECHILD)) 240346afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags); 24042d864651SAl Viro if (unlikely(error == -ESTALE)) 240546afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_REVAL); 24062d864651SAl Viro if (likely(!error)) 2407668696dcSAl Viro audit_inode(name, path->dentry, 0); 2408668696dcSAl Viro putname(name); 24092d864651SAl Viro return error; 24102d864651SAl Viro } 24112d864651SAl Viro 24128033426eSJeff Layton /** 2413197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 24148033426eSJeff Layton * @dfd: directory file descriptor 24158033426eSJeff Layton * @name: pathname from userland 24168033426eSJeff Layton * @flags: lookup flags 24178033426eSJeff Layton * @path: pointer to container to hold result 24188033426eSJeff Layton * 24198033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 24208033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 24218033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 24228033426eSJeff Layton * and avoid revalidating the last component. 24238033426eSJeff Layton * 24248033426eSJeff Layton * Returns 0 and populates "path" on success. 24258033426eSJeff Layton */ 24268033426eSJeff Layton int 2427197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 24288033426eSJeff Layton struct path *path) 24298033426eSJeff Layton { 2430cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 24318033426eSJeff Layton } 24328033426eSJeff Layton 24332d864651SAl Viro int 24342d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 24352d864651SAl Viro unsigned int flags) 24362d864651SAl Viro { 2437cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 24382d864651SAl Viro } 24392d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 24402d864651SAl Viro 2441cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 24421da177e4SLinus Torvalds { 24438e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2444da9592edSDavid Howells 24458e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 24461da177e4SLinus Torvalds return 0; 24478e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 24481da177e4SLinus Torvalds return 0; 244923adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 24501da177e4SLinus Torvalds } 2451cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 24521da177e4SLinus Torvalds 24531da177e4SLinus Torvalds /* 24541da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 24551da177e4SLinus Torvalds * whether the type of victim is right. 24561da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 24571da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 24581da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 24591da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 24601da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 24611da177e4SLinus Torvalds * a. be owner of dir, or 24621da177e4SLinus Torvalds * b. be owner of victim, or 24631da177e4SLinus Torvalds * c. have CAP_FOWNER capability 24641da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 24651da177e4SLinus Torvalds * links pointing to it. 24661da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 24671da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 24681da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 24691da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 24701da177e4SLinus Torvalds * nfs_async_unlink(). 24711da177e4SLinus Torvalds */ 2472b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 24731da177e4SLinus Torvalds { 2474b18825a7SDavid Howells struct inode *inode = victim->d_inode; 24751da177e4SLinus Torvalds int error; 24761da177e4SLinus Torvalds 2477b18825a7SDavid Howells if (d_is_negative(victim)) 24781da177e4SLinus Torvalds return -ENOENT; 2479b18825a7SDavid Howells BUG_ON(!inode); 24801da177e4SLinus Torvalds 24811da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 24824fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 24831da177e4SLinus Torvalds 2484f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 24851da177e4SLinus Torvalds if (error) 24861da177e4SLinus Torvalds return error; 24871da177e4SLinus Torvalds if (IS_APPEND(dir)) 24881da177e4SLinus Torvalds return -EPERM; 2489b18825a7SDavid Howells 2490b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2491b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 24921da177e4SLinus Torvalds return -EPERM; 24931da177e4SLinus Torvalds if (isdir) { 249444b1d530SMiklos Szeredi if (!d_is_dir(victim)) 24951da177e4SLinus Torvalds return -ENOTDIR; 24961da177e4SLinus Torvalds if (IS_ROOT(victim)) 24971da177e4SLinus Torvalds return -EBUSY; 249844b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 24991da177e4SLinus Torvalds return -EISDIR; 25001da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25011da177e4SLinus Torvalds return -ENOENT; 25021da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 25031da177e4SLinus Torvalds return -EBUSY; 25041da177e4SLinus Torvalds return 0; 25051da177e4SLinus Torvalds } 25061da177e4SLinus Torvalds 25071da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 25081da177e4SLinus Torvalds * dir. 25091da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 25101da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 25111da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 25121da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 25131da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 25141da177e4SLinus Torvalds */ 2515a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 25161da177e4SLinus Torvalds { 251714e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 25181da177e4SLinus Torvalds if (child->d_inode) 25191da177e4SLinus Torvalds return -EEXIST; 25201da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25211da177e4SLinus Torvalds return -ENOENT; 2522f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 25231da177e4SLinus Torvalds } 25241da177e4SLinus Torvalds 25251da177e4SLinus Torvalds /* 25261da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 25271da177e4SLinus Torvalds */ 25281da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 25291da177e4SLinus Torvalds { 25301da177e4SLinus Torvalds struct dentry *p; 25311da177e4SLinus Torvalds 25321da177e4SLinus Torvalds if (p1 == p2) { 2533f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 25341da177e4SLinus Torvalds return NULL; 25351da177e4SLinus Torvalds } 25361da177e4SLinus Torvalds 2537a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25381da177e4SLinus Torvalds 2539e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2540e2761a11SOGAWA Hirofumi if (p) { 2541f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2542f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 25431da177e4SLinus Torvalds return p; 25441da177e4SLinus Torvalds } 25451da177e4SLinus Torvalds 2546e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2547e2761a11SOGAWA Hirofumi if (p) { 2548f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2549f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 25501da177e4SLinus Torvalds return p; 25511da177e4SLinus Torvalds } 25521da177e4SLinus Torvalds 2553f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2554d1b72cc6SMiklos Szeredi mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); 25551da177e4SLinus Torvalds return NULL; 25561da177e4SLinus Torvalds } 25574d359507SAl Viro EXPORT_SYMBOL(lock_rename); 25581da177e4SLinus Torvalds 25591da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 25601da177e4SLinus Torvalds { 25611b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 25621da177e4SLinus Torvalds if (p1 != p2) { 25631b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2564a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25651da177e4SLinus Torvalds } 25661da177e4SLinus Torvalds } 25674d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 25681da177e4SLinus Torvalds 25694acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2570312b63fbSAl Viro bool want_excl) 25711da177e4SLinus Torvalds { 2572a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 25731da177e4SLinus Torvalds if (error) 25741da177e4SLinus Torvalds return error; 25751da177e4SLinus Torvalds 2576acfa4380SAl Viro if (!dir->i_op->create) 25771da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 25781da177e4SLinus Torvalds mode &= S_IALLUGO; 25791da177e4SLinus Torvalds mode |= S_IFREG; 25801da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 25811da177e4SLinus Torvalds if (error) 25821da177e4SLinus Torvalds return error; 2583312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2584a74574aaSStephen Smalley if (!error) 2585f38aa942SAmy Griffis fsnotify_create(dir, dentry); 25861da177e4SLinus Torvalds return error; 25871da177e4SLinus Torvalds } 25884d359507SAl Viro EXPORT_SYMBOL(vfs_create); 25891da177e4SLinus Torvalds 259073d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 25911da177e4SLinus Torvalds { 25923fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 25931da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 25941da177e4SLinus Torvalds int error; 25951da177e4SLinus Torvalds 2596bcda7652SAl Viro /* O_PATH? */ 2597bcda7652SAl Viro if (!acc_mode) 2598bcda7652SAl Viro return 0; 2599bcda7652SAl Viro 26001da177e4SLinus Torvalds if (!inode) 26011da177e4SLinus Torvalds return -ENOENT; 26021da177e4SLinus Torvalds 2603c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2604c8fe8f30SChristoph Hellwig case S_IFLNK: 26051da177e4SLinus Torvalds return -ELOOP; 2606c8fe8f30SChristoph Hellwig case S_IFDIR: 2607c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 26081da177e4SLinus Torvalds return -EISDIR; 2609c8fe8f30SChristoph Hellwig break; 2610c8fe8f30SChristoph Hellwig case S_IFBLK: 2611c8fe8f30SChristoph Hellwig case S_IFCHR: 26123fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 26131da177e4SLinus Torvalds return -EACCES; 2614c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2615c8fe8f30SChristoph Hellwig case S_IFIFO: 2616c8fe8f30SChristoph Hellwig case S_IFSOCK: 26171da177e4SLinus Torvalds flag &= ~O_TRUNC; 2618c8fe8f30SChristoph Hellwig break; 26194a3fd211SDave Hansen } 2620b41572e9SDave Hansen 26213fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2622b41572e9SDave Hansen if (error) 2623b41572e9SDave Hansen return error; 26246146f0d5SMimi Zohar 26251da177e4SLinus Torvalds /* 26261da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 26271da177e4SLinus Torvalds */ 26281da177e4SLinus Torvalds if (IS_APPEND(inode)) { 26298737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 26307715b521SAl Viro return -EPERM; 26311da177e4SLinus Torvalds if (flag & O_TRUNC) 26327715b521SAl Viro return -EPERM; 26331da177e4SLinus Torvalds } 26341da177e4SLinus Torvalds 26351da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 26362e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 26377715b521SAl Viro return -EPERM; 26381da177e4SLinus Torvalds 2639f3c7691eSJ. Bruce Fields return 0; 26407715b521SAl Viro } 26417715b521SAl Viro 2642e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 26437715b521SAl Viro { 2644e1181ee6SJeff Layton struct path *path = &filp->f_path; 26457715b521SAl Viro struct inode *inode = path->dentry->d_inode; 26467715b521SAl Viro int error = get_write_access(inode); 26471da177e4SLinus Torvalds if (error) 26487715b521SAl Viro return error; 26491da177e4SLinus Torvalds /* 26501da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 26511da177e4SLinus Torvalds */ 2652d7a06983SJeff Layton error = locks_verify_locked(filp); 2653be6d3e56SKentaro Takeda if (!error) 2654ea0d3ab2STetsuo Handa error = security_path_truncate(path); 26551da177e4SLinus Torvalds if (!error) { 26567715b521SAl Viro error = do_truncate(path->dentry, 0, 2657d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2658e1181ee6SJeff Layton filp); 26591da177e4SLinus Torvalds } 26601da177e4SLinus Torvalds put_write_access(inode); 2661acd0c935SMimi Zohar return error; 26621da177e4SLinus Torvalds } 26631da177e4SLinus Torvalds 2664d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2665d57999e1SDave Hansen { 26668a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 26678a5e929dSAl Viro flag--; 2668d57999e1SDave Hansen return flag; 2669d57999e1SDave Hansen } 2670d57999e1SDave Hansen 2671d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2672d18e9008SMiklos Szeredi { 2673d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2674d18e9008SMiklos Szeredi if (error) 2675d18e9008SMiklos Szeredi return error; 2676d18e9008SMiklos Szeredi 2677d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2678d18e9008SMiklos Szeredi if (error) 2679d18e9008SMiklos Szeredi return error; 2680d18e9008SMiklos Szeredi 2681d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2682d18e9008SMiklos Szeredi } 2683d18e9008SMiklos Szeredi 26841acf0af9SDavid Howells /* 26851acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 26861acf0af9SDavid Howells * dentry. 26871acf0af9SDavid Howells * 26881acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 26891acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 26901acf0af9SDavid Howells * 26911acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 26921acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 26931acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 26941acf0af9SDavid Howells * 26951acf0af9SDavid Howells * Returns an error code otherwise. 26961acf0af9SDavid Howells */ 26972675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 269830d90494SAl Viro struct path *path, struct file *file, 2699015c3bbcSMiklos Szeredi const struct open_flags *op, 270064894cf8SAl Viro bool got_write, bool need_lookup, 270147237687SAl Viro int *opened) 2702d18e9008SMiklos Szeredi { 2703d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2704d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2705d18e9008SMiklos Szeredi umode_t mode; 2706d18e9008SMiklos Szeredi int error; 2707d18e9008SMiklos Szeredi int acc_mode; 2708d18e9008SMiklos Szeredi int create_error = 0; 2709d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2710116cc022SMiklos Szeredi bool excl; 2711d18e9008SMiklos Szeredi 2712d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2713d18e9008SMiklos Szeredi 2714d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2715d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 27162675a4ebSAl Viro error = -ENOENT; 2717d18e9008SMiklos Szeredi goto out; 2718d18e9008SMiklos Szeredi } 2719d18e9008SMiklos Szeredi 272062b259d8SMiklos Szeredi mode = op->mode; 2721d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2722d18e9008SMiklos Szeredi mode &= ~current_umask(); 2723d18e9008SMiklos Szeredi 2724116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2725116cc022SMiklos Szeredi if (excl) 2726d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2727d18e9008SMiklos Szeredi 2728d18e9008SMiklos Szeredi /* 2729d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2730d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2731d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2732d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2733d18e9008SMiklos Szeredi * 2734d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2735d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2736d18e9008SMiklos Szeredi */ 273764894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 273864894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 273964894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2740d18e9008SMiklos Szeredi /* 2741d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2742d18e9008SMiklos Szeredi * back to lookup + open 2743d18e9008SMiklos Szeredi */ 2744d18e9008SMiklos Szeredi goto no_open; 2745d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2746d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 274764894cf8SAl Viro create_error = -EROFS; 2748d18e9008SMiklos Szeredi goto no_open; 2749d18e9008SMiklos Szeredi } else { 2750d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 275164894cf8SAl Viro create_error = -EROFS; 2752d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2753d18e9008SMiklos Szeredi } 2754d18e9008SMiklos Szeredi } 2755d18e9008SMiklos Szeredi 2756d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 275738227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2758d18e9008SMiklos Szeredi if (error) { 2759d18e9008SMiklos Szeredi create_error = error; 2760d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2761d18e9008SMiklos Szeredi goto no_open; 2762d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2763d18e9008SMiklos Szeredi } 2764d18e9008SMiklos Szeredi } 2765d18e9008SMiklos Szeredi 2766d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2767d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2768d18e9008SMiklos Szeredi 276930d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 277030d90494SAl Viro file->f_path.mnt = nd->path.mnt; 277130d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 277247237687SAl Viro opened); 2773d9585277SAl Viro if (error < 0) { 2774d9585277SAl Viro if (create_error && error == -ENOENT) 2775d9585277SAl Viro error = create_error; 2776d18e9008SMiklos Szeredi goto out; 2777d18e9008SMiklos Szeredi } 2778d18e9008SMiklos Szeredi 2779d9585277SAl Viro if (error) { /* returned 1, that is */ 278030d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 27812675a4ebSAl Viro error = -EIO; 2782d18e9008SMiklos Szeredi goto out; 2783d18e9008SMiklos Szeredi } 278430d90494SAl Viro if (file->f_path.dentry) { 2785d18e9008SMiklos Szeredi dput(dentry); 278630d90494SAl Viro dentry = file->f_path.dentry; 2787d18e9008SMiklos Szeredi } 278803da633aSAl Viro if (*opened & FILE_CREATED) 278903da633aSAl Viro fsnotify_create(dir, dentry); 279003da633aSAl Viro if (!dentry->d_inode) { 279103da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 279203da633aSAl Viro if (create_error) { 279362b2ce96SSage Weil error = create_error; 279462b2ce96SSage Weil goto out; 279562b2ce96SSage Weil } 279603da633aSAl Viro } else { 279703da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 279803da633aSAl Viro error = -EEXIST; 279903da633aSAl Viro goto out; 280003da633aSAl Viro } 280103da633aSAl Viro } 2802d18e9008SMiklos Szeredi goto looked_up; 2803d18e9008SMiklos Szeredi } 2804d18e9008SMiklos Szeredi 2805d18e9008SMiklos Szeredi /* 2806d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2807d18e9008SMiklos Szeredi * here. 2808d18e9008SMiklos Szeredi */ 280903da633aSAl Viro acc_mode = op->acc_mode; 281003da633aSAl Viro if (*opened & FILE_CREATED) { 281103da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 281203da633aSAl Viro fsnotify_create(dir, dentry); 281303da633aSAl Viro acc_mode = MAY_OPEN; 281403da633aSAl Viro } 28152675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 28162675a4ebSAl Viro if (error) 28172675a4ebSAl Viro fput(file); 2818d18e9008SMiklos Szeredi 2819d18e9008SMiklos Szeredi out: 2820d18e9008SMiklos Szeredi dput(dentry); 28212675a4ebSAl Viro return error; 2822d18e9008SMiklos Szeredi 2823d18e9008SMiklos Szeredi no_open: 2824d18e9008SMiklos Szeredi if (need_lookup) { 282572bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2826d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 28272675a4ebSAl Viro return PTR_ERR(dentry); 2828d18e9008SMiklos Szeredi 2829d18e9008SMiklos Szeredi if (create_error) { 2830d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2831d18e9008SMiklos Szeredi 28322675a4ebSAl Viro error = create_error; 2833d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2834d18e9008SMiklos Szeredi if (!dentry->d_inode) 2835d18e9008SMiklos Szeredi goto out; 2836d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2837d18e9008SMiklos Szeredi goto out; 2838d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2839e36cb0b8SDavid Howells d_is_reg(dentry)) { 2840d18e9008SMiklos Szeredi goto out; 2841d18e9008SMiklos Szeredi } 2842d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2843d18e9008SMiklos Szeredi } 2844d18e9008SMiklos Szeredi } 2845d18e9008SMiklos Szeredi looked_up: 2846d18e9008SMiklos Szeredi path->dentry = dentry; 2847d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 28482675a4ebSAl Viro return 1; 2849d18e9008SMiklos Szeredi } 2850d18e9008SMiklos Szeredi 285131e6b01fSNick Piggin /* 28521acf0af9SDavid Howells * Look up and maybe create and open the last component. 2853d58ffd35SMiklos Szeredi * 2854d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2855d58ffd35SMiklos Szeredi * 28561acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 28571acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 28581acf0af9SDavid Howells * 28591acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 28601acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 28611acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 28621acf0af9SDavid Howells * specified then a negative dentry may be returned. 28631acf0af9SDavid Howells * 28641acf0af9SDavid Howells * An error code is returned otherwise. 28651acf0af9SDavid Howells * 28661acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 28671acf0af9SDavid Howells * cleared otherwise prior to returning. 2868d58ffd35SMiklos Szeredi */ 28692675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 287030d90494SAl Viro struct file *file, 2871d58ffd35SMiklos Szeredi const struct open_flags *op, 287264894cf8SAl Viro bool got_write, int *opened) 2873d58ffd35SMiklos Szeredi { 2874d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 287554ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2876d58ffd35SMiklos Szeredi struct dentry *dentry; 2877d58ffd35SMiklos Szeredi int error; 287854ef4872SMiklos Szeredi bool need_lookup; 2879d58ffd35SMiklos Szeredi 288047237687SAl Viro *opened &= ~FILE_CREATED; 2881201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2882d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 28832675a4ebSAl Viro return PTR_ERR(dentry); 2884d58ffd35SMiklos Szeredi 2885d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2886d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2887d18e9008SMiklos Szeredi goto out_no_open; 2888d18e9008SMiklos Szeredi 2889d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 289064894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 289147237687SAl Viro need_lookup, opened); 2892d18e9008SMiklos Szeredi } 2893d18e9008SMiklos Szeredi 289454ef4872SMiklos Szeredi if (need_lookup) { 289554ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 289654ef4872SMiklos Szeredi 289772bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 289854ef4872SMiklos Szeredi if (IS_ERR(dentry)) 28992675a4ebSAl Viro return PTR_ERR(dentry); 290054ef4872SMiklos Szeredi } 290154ef4872SMiklos Szeredi 2902d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2903d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2904d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2905d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2906d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2907d58ffd35SMiklos Szeredi /* 2908d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2909d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2910d58ffd35SMiklos Szeredi * the time when the file is created and when 2911d58ffd35SMiklos Szeredi * a permanent write count is taken through 2912015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 2913d58ffd35SMiklos Szeredi */ 291464894cf8SAl Viro if (!got_write) { 291564894cf8SAl Viro error = -EROFS; 2916d58ffd35SMiklos Szeredi goto out_dput; 291764894cf8SAl Viro } 291847237687SAl Viro *opened |= FILE_CREATED; 2919d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2920d58ffd35SMiklos Szeredi if (error) 2921d58ffd35SMiklos Szeredi goto out_dput; 2922312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 2923312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 2924d58ffd35SMiklos Szeredi if (error) 2925d58ffd35SMiklos Szeredi goto out_dput; 2926d58ffd35SMiklos Szeredi } 2927d18e9008SMiklos Szeredi out_no_open: 2928d58ffd35SMiklos Szeredi path->dentry = dentry; 2929d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 29302675a4ebSAl Viro return 1; 2931d58ffd35SMiklos Szeredi 2932d58ffd35SMiklos Szeredi out_dput: 2933d58ffd35SMiklos Szeredi dput(dentry); 29342675a4ebSAl Viro return error; 2935d58ffd35SMiklos Szeredi } 2936d58ffd35SMiklos Szeredi 2937d58ffd35SMiklos Szeredi /* 2938fe2d35ffSAl Viro * Handle the last step of open() 293931e6b01fSNick Piggin */ 2940896475d5SAl Viro static int do_last(struct nameidata *nd, 294130d90494SAl Viro struct file *file, const struct open_flags *op, 2942669abf4eSJeff Layton int *opened, struct filename *name) 2943fb1cc555SAl Viro { 2944a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2945ca344a89SAl Viro int open_flag = op->open_flag; 294677d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 294764894cf8SAl Viro bool got_write = false; 2948bcda7652SAl Viro int acc_mode = op->acc_mode; 2949a1eb3315SMiklos Szeredi struct inode *inode; 295016b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 2951896475d5SAl Viro struct path path; 295216b1c1cdSMiklos Szeredi bool retried = false; 295316c2cd71SAl Viro int error; 2954fb1cc555SAl Viro 2955c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2956c3e380b0SAl Viro nd->flags |= op->intent; 2957c3e380b0SAl Viro 2958bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 2959fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2960fe2d35ffSAl Viro if (error) 29612675a4ebSAl Viro return error; 2962e83db167SMiklos Szeredi goto finish_open; 29631f36f774SAl Viro } 2964a2c36b45SAl Viro 2965ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2966fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2967fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2968fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2969896475d5SAl Viro error = lookup_fast(nd, &path, &inode); 297071574865SMiklos Szeredi if (likely(!error)) 297171574865SMiklos Szeredi goto finish_lookup; 297271574865SMiklos Szeredi 2973ce57dfc1SAl Viro if (error < 0) 29742675a4ebSAl Viro goto out; 2975a1eb3315SMiklos Szeredi 297637d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 2977b6183df7SMiklos Szeredi } else { 2978fe2d35ffSAl Viro /* create side of things */ 2979a3fbbde7SAl Viro /* 2980b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 2981b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 2982b6183df7SMiklos Szeredi * about to look up 2983a3fbbde7SAl Viro */ 29849f1fafeeSAl Viro error = complete_walk(nd); 29859f1fafeeSAl Viro if (error) 29862675a4ebSAl Viro return error; 2987fe2d35ffSAl Viro 298833e2208aSJeff Layton audit_inode(name, dir, LOOKUP_PARENT); 298916c2cd71SAl Viro error = -EISDIR; 29901f36f774SAl Viro /* trailing slashes? */ 299131e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 29922675a4ebSAl Viro goto out; 2993b6183df7SMiklos Szeredi } 29941f36f774SAl Viro 299516b1c1cdSMiklos Szeredi retry_lookup: 299664894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 299764894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 299864894cf8SAl Viro if (!error) 299964894cf8SAl Viro got_write = true; 300064894cf8SAl Viro /* 300164894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 300264894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 300364894cf8SAl Viro * dropping this one anyway. 300464894cf8SAl Viro */ 300564894cf8SAl Viro } 3006a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 3007896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 3008fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 3009fb1cc555SAl Viro 30102675a4ebSAl Viro if (error <= 0) { 30112675a4ebSAl Viro if (error) 3012d58ffd35SMiklos Szeredi goto out; 30136c0d46c4SAl Viro 301447237687SAl Viro if ((*opened & FILE_CREATED) || 3015496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 301677d660a8SMiklos Szeredi will_truncate = false; 3017d18e9008SMiklos Szeredi 3018adb5c247SJeff Layton audit_inode(name, file->f_path.dentry, 0); 3019d18e9008SMiklos Szeredi goto opened; 3020d18e9008SMiklos Szeredi } 3021d18e9008SMiklos Szeredi 302247237687SAl Viro if (*opened & FILE_CREATED) { 30239b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3024ca344a89SAl Viro open_flag &= ~O_TRUNC; 302577d660a8SMiklos Szeredi will_truncate = false; 3026bcda7652SAl Viro acc_mode = MAY_OPEN; 3027896475d5SAl Viro path_to_nameidata(&path, nd); 3028e83db167SMiklos Szeredi goto finish_open_created; 3029fb1cc555SAl Viro } 3030fb1cc555SAl Viro 3031fb1cc555SAl Viro /* 30323134f37eSJeff Layton * create/update audit record if it already exists. 3033fb1cc555SAl Viro */ 3034896475d5SAl Viro if (d_is_positive(path.dentry)) 3035896475d5SAl Viro audit_inode(name, path.dentry, 0); 3036fb1cc555SAl Viro 3037d18e9008SMiklos Szeredi /* 3038d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3039d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3040d18e9008SMiklos Szeredi * necessary...) 3041d18e9008SMiklos Szeredi */ 304264894cf8SAl Viro if (got_write) { 3043d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 304464894cf8SAl Viro got_write = false; 3045d18e9008SMiklos Szeredi } 3046d18e9008SMiklos Szeredi 3047fb1cc555SAl Viro error = -EEXIST; 3048f8310c59SAl Viro if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) 3049fb1cc555SAl Viro goto exit_dput; 3050fb1cc555SAl Viro 3051896475d5SAl Viro error = follow_managed(&path, nd->flags); 30529875cf80SDavid Howells if (error < 0) 3053fb1cc555SAl Viro goto exit_dput; 3054fb1cc555SAl Viro 3055a3fbbde7SAl Viro if (error) 3056a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 3057a3fbbde7SAl Viro 3058decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 3059896475d5SAl Viro inode = path.dentry->d_inode; 3060fb1cc555SAl Viro error = -ENOENT; 3061896475d5SAl Viro if (d_is_negative(path.dentry)) { 3062896475d5SAl Viro path_to_nameidata(&path, nd); 30632675a4ebSAl Viro goto out; 306454c33e7fSMiklos Szeredi } 3065766c4cbfSAl Viro finish_lookup: 3066896475d5SAl Viro if (should_follow_link(path.dentry, nd->flags & LOOKUP_FOLLOW)) { 3067d45ea867SMiklos Szeredi if (nd->flags & LOOKUP_RCU) { 3068896475d5SAl Viro if (unlikely(nd->path.mnt != path.mnt || 3069896475d5SAl Viro unlazy_walk(nd, path.dentry))) { 3070d45ea867SMiklos Szeredi error = -ECHILD; 30712675a4ebSAl Viro goto out; 3072d45ea867SMiklos Szeredi } 3073d45ea867SMiklos Szeredi } 3074896475d5SAl Viro BUG_ON(inode != path.dentry->d_inode); 3075896475d5SAl Viro nd->link = path; 30762675a4ebSAl Viro return 1; 3077d45ea867SMiklos Szeredi } 3078fb1cc555SAl Viro 3079896475d5SAl Viro if (unlikely(d_is_symlink(path.dentry)) && !(open_flag & O_PATH)) { 3080896475d5SAl Viro path_to_nameidata(&path, nd); 3081a5cfe2d5SAl Viro error = -ELOOP; 3082a5cfe2d5SAl Viro goto out; 3083a5cfe2d5SAl Viro } 3084a5cfe2d5SAl Viro 3085896475d5SAl Viro if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { 3086896475d5SAl Viro path_to_nameidata(&path, nd); 308716b1c1cdSMiklos Szeredi } else { 308816b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 3089896475d5SAl Viro save_parent.mnt = mntget(path.mnt); 3090896475d5SAl Viro nd->path.dentry = path.dentry; 309116b1c1cdSMiklos Szeredi 309216b1c1cdSMiklos Szeredi } 3093decf3400SMiklos Szeredi nd->inode = inode; 3094a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3095bc77daa7SAl Viro finish_open: 3096a3fbbde7SAl Viro error = complete_walk(nd); 309716b1c1cdSMiklos Szeredi if (error) { 309816b1c1cdSMiklos Szeredi path_put(&save_parent); 30992675a4ebSAl Viro return error; 310016b1c1cdSMiklos Szeredi } 3101bc77daa7SAl Viro audit_inode(name, nd->path.dentry, 0); 3102fb1cc555SAl Viro error = -EISDIR; 310344b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 31042675a4ebSAl Viro goto out; 3105af2f5542SMiklos Szeredi error = -ENOTDIR; 310644b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 31072675a4ebSAl Viro goto out; 31084bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 310977d660a8SMiklos Szeredi will_truncate = false; 31106c0d46c4SAl Viro 31110f9d1a10SAl Viro if (will_truncate) { 31120f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 31130f9d1a10SAl Viro if (error) 31142675a4ebSAl Viro goto out; 311564894cf8SAl Viro got_write = true; 31160f9d1a10SAl Viro } 3117e83db167SMiklos Szeredi finish_open_created: 3118bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3119ca344a89SAl Viro if (error) 31202675a4ebSAl Viro goto out; 31214aa7c634SMiklos Szeredi 31224aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 31234aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 31244aa7c634SMiklos Szeredi if (!error) { 31254aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 31264aa7c634SMiklos Szeredi } else { 312730d90494SAl Viro if (error == -EOPENSTALE) 3128f60dc3dbSMiklos Szeredi goto stale_open; 3129015c3bbcSMiklos Szeredi goto out; 3130f60dc3dbSMiklos Szeredi } 3131a8277b9bSMiklos Szeredi opened: 31322675a4ebSAl Viro error = open_check_o_direct(file); 3133015c3bbcSMiklos Szeredi if (error) 3134015c3bbcSMiklos Szeredi goto exit_fput; 31353034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3136aa4caadbSMiklos Szeredi if (error) 3137aa4caadbSMiklos Szeredi goto exit_fput; 3138aa4caadbSMiklos Szeredi 31390f9d1a10SAl Viro if (will_truncate) { 31402675a4ebSAl Viro error = handle_truncate(file); 3141aa4caadbSMiklos Szeredi if (error) 3142aa4caadbSMiklos Szeredi goto exit_fput; 31430f9d1a10SAl Viro } 3144ca344a89SAl Viro out: 314564894cf8SAl Viro if (got_write) 31460f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 314716b1c1cdSMiklos Szeredi path_put(&save_parent); 3148e276ae67SMiklos Szeredi terminate_walk(nd); 31492675a4ebSAl Viro return error; 3150fb1cc555SAl Viro 3151fb1cc555SAl Viro exit_dput: 3152896475d5SAl Viro path_put_conditional(&path, nd); 3153ca344a89SAl Viro goto out; 3154015c3bbcSMiklos Szeredi exit_fput: 31552675a4ebSAl Viro fput(file); 31562675a4ebSAl Viro goto out; 3157015c3bbcSMiklos Szeredi 3158f60dc3dbSMiklos Szeredi stale_open: 3159f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3160f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3161f60dc3dbSMiklos Szeredi goto out; 3162f60dc3dbSMiklos Szeredi 3163f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3164f60dc3dbSMiklos Szeredi path_put(&nd->path); 3165f60dc3dbSMiklos Szeredi nd->path = save_parent; 3166f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3167f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3168f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 316964894cf8SAl Viro if (got_write) { 3170f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 317164894cf8SAl Viro got_write = false; 3172f60dc3dbSMiklos Szeredi } 3173f60dc3dbSMiklos Szeredi retried = true; 3174f60dc3dbSMiklos Szeredi goto retry_lookup; 3175fb1cc555SAl Viro } 3176fb1cc555SAl Viro 317760545d0dSAl Viro static int do_tmpfile(int dfd, struct filename *pathname, 317860545d0dSAl Viro struct nameidata *nd, int flags, 317960545d0dSAl Viro const struct open_flags *op, 318060545d0dSAl Viro struct file *file, int *opened) 318160545d0dSAl Viro { 318260545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 318360545d0dSAl Viro struct dentry *dentry, *child; 318460545d0dSAl Viro struct inode *dir; 31855eb6b495SAl Viro int error = path_lookupat(dfd, pathname, 318660545d0dSAl Viro flags | LOOKUP_DIRECTORY, nd); 318760545d0dSAl Viro if (unlikely(error)) 318860545d0dSAl Viro return error; 318960545d0dSAl Viro error = mnt_want_write(nd->path.mnt); 319060545d0dSAl Viro if (unlikely(error)) 319160545d0dSAl Viro goto out; 319260545d0dSAl Viro /* we want directory to be writable */ 319360545d0dSAl Viro error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); 319460545d0dSAl Viro if (error) 319560545d0dSAl Viro goto out2; 319660545d0dSAl Viro dentry = nd->path.dentry; 319760545d0dSAl Viro dir = dentry->d_inode; 319860545d0dSAl Viro if (!dir->i_op->tmpfile) { 319960545d0dSAl Viro error = -EOPNOTSUPP; 320060545d0dSAl Viro goto out2; 320160545d0dSAl Viro } 320260545d0dSAl Viro child = d_alloc(dentry, &name); 320360545d0dSAl Viro if (unlikely(!child)) { 320460545d0dSAl Viro error = -ENOMEM; 320560545d0dSAl Viro goto out2; 320660545d0dSAl Viro } 320760545d0dSAl Viro nd->flags &= ~LOOKUP_DIRECTORY; 320860545d0dSAl Viro nd->flags |= op->intent; 320960545d0dSAl Viro dput(nd->path.dentry); 321060545d0dSAl Viro nd->path.dentry = child; 321160545d0dSAl Viro error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); 321260545d0dSAl Viro if (error) 321360545d0dSAl Viro goto out2; 321460545d0dSAl Viro audit_inode(pathname, nd->path.dentry, 0); 321569a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 321669a91c23SEric Rannaud error = may_open(&nd->path, MAY_OPEN, op->open_flag); 321760545d0dSAl Viro if (error) 321860545d0dSAl Viro goto out2; 321960545d0dSAl Viro file->f_path.mnt = nd->path.mnt; 322060545d0dSAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 322160545d0dSAl Viro if (error) 322260545d0dSAl Viro goto out2; 322360545d0dSAl Viro error = open_check_o_direct(file); 3224f4e0c30cSAl Viro if (error) { 322560545d0dSAl Viro fput(file); 3226f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3227f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3228f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3229f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3230f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3231f4e0c30cSAl Viro } 323260545d0dSAl Viro out2: 323360545d0dSAl Viro mnt_drop_write(nd->path.mnt); 323460545d0dSAl Viro out: 323560545d0dSAl Viro path_put(&nd->path); 323660545d0dSAl Viro return error; 323760545d0dSAl Viro } 323860545d0dSAl Viro 3239669abf4eSJeff Layton static struct file *path_openat(int dfd, struct filename *pathname, 324073d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 32411da177e4SLinus Torvalds { 324230d90494SAl Viro struct file *file; 324347237687SAl Viro int opened = 0; 324413aab428SAl Viro int error; 324531e6b01fSNick Piggin 324630d90494SAl Viro file = get_empty_filp(); 32471afc99beSAl Viro if (IS_ERR(file)) 32481afc99beSAl Viro return file; 324931e6b01fSNick Piggin 325030d90494SAl Viro file->f_flags = op->open_flag; 325131e6b01fSNick Piggin 3252bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 325360545d0dSAl Viro error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); 3254f15133dfSAl Viro goto out2; 325560545d0dSAl Viro } 325660545d0dSAl Viro 32576e8a1f87SAl Viro error = path_init(dfd, pathname, flags, nd); 325831e6b01fSNick Piggin if (unlikely(error)) 32592675a4ebSAl Viro goto out; 32601da177e4SLinus Torvalds 3261896475d5SAl Viro error = do_last(nd, file, op, &opened, pathname); 32622675a4ebSAl Viro while (unlikely(error > 0)) { /* trailing symlink */ 326373d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 3264697fc6caSAl Viro nd->stack[0].link = nd->link; 3265697fc6caSAl Viro error= trailing_symlink(&nd->stack[0].link, 3266697fc6caSAl Viro nd, &nd->stack[0].cookie); 3267c3e380b0SAl Viro if (unlikely(error)) 32682675a4ebSAl Viro break; 3269896475d5SAl Viro error = do_last(nd, file, op, &opened, pathname); 3270697fc6caSAl Viro put_link(nd, &nd->stack[0].link, nd->stack[0].cookie); 3271806b681cSAl Viro } 327210fa8e62SAl Viro out: 3273893b7775SAl Viro path_cleanup(nd); 3274f15133dfSAl Viro out2: 32752675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 32762675a4ebSAl Viro BUG_ON(!error); 327730d90494SAl Viro put_filp(file); 3278015c3bbcSMiklos Szeredi } 32792675a4ebSAl Viro if (unlikely(error)) { 32802675a4ebSAl Viro if (error == -EOPENSTALE) { 32812675a4ebSAl Viro if (flags & LOOKUP_RCU) 32822675a4ebSAl Viro error = -ECHILD; 32832675a4ebSAl Viro else 32842675a4ebSAl Viro error = -ESTALE; 32852675a4ebSAl Viro } 32862675a4ebSAl Viro file = ERR_PTR(error); 32872675a4ebSAl Viro } 32882675a4ebSAl Viro return file; 3289de459215SKirill Korotaev } 32901da177e4SLinus Torvalds 3291669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3292f9652e10SAl Viro const struct open_flags *op) 329313aab428SAl Viro { 329473d049a4SAl Viro struct nameidata nd; 3295f9652e10SAl Viro int flags = op->lookup_flags; 329613aab428SAl Viro struct file *filp; 329713aab428SAl Viro 329873d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 329913aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 330073d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 330113aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 330273d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 330313aab428SAl Viro return filp; 330413aab428SAl Viro } 330513aab428SAl Viro 330673d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3307f9652e10SAl Viro const char *name, const struct open_flags *op) 330873d049a4SAl Viro { 330973d049a4SAl Viro struct nameidata nd; 331073d049a4SAl Viro struct file *file; 331151689104SPaul Moore struct filename *filename; 3312f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 331373d049a4SAl Viro 331473d049a4SAl Viro nd.root.mnt = mnt; 331573d049a4SAl Viro nd.root.dentry = dentry; 331673d049a4SAl Viro 3317b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 331873d049a4SAl Viro return ERR_PTR(-ELOOP); 331973d049a4SAl Viro 332051689104SPaul Moore filename = getname_kernel(name); 332151689104SPaul Moore if (unlikely(IS_ERR(filename))) 332251689104SPaul Moore return ERR_CAST(filename); 332351689104SPaul Moore 332451689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_RCU); 332573d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 332651689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags); 332773d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 332851689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_REVAL); 332951689104SPaul Moore putname(filename); 333073d049a4SAl Viro return file; 333173d049a4SAl Viro } 333273d049a4SAl Viro 3333fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 33341ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 33351da177e4SLinus Torvalds { 3336c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3337ed75e95dSAl Viro struct nameidata nd; 3338c30dabfeSJan Kara int err2; 33391ac12b4bSJeff Layton int error; 33401ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 33411ac12b4bSJeff Layton 33421ac12b4bSJeff Layton /* 33431ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 33441ac12b4bSJeff Layton * other flags passed in are ignored! 33451ac12b4bSJeff Layton */ 33461ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 33471ac12b4bSJeff Layton 3348fa14a0b8SAl Viro error = filename_lookup(dfd, name, LOOKUP_PARENT|lookup_flags, &nd); 3349ed75e95dSAl Viro if (error) 3350ed75e95dSAl Viro return ERR_PTR(error); 33511da177e4SLinus Torvalds 3352c663e5d8SChristoph Hellwig /* 3353c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3354c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3355c663e5d8SChristoph Hellwig */ 3356ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 3357ed75e95dSAl Viro goto out; 3358ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 3359ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 3360c663e5d8SChristoph Hellwig 3361c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3362c30dabfeSJan Kara err2 = mnt_want_write(nd.path.mnt); 3363c663e5d8SChristoph Hellwig /* 3364c663e5d8SChristoph Hellwig * Do the final lookup. 3365c663e5d8SChristoph Hellwig */ 3366ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 33676a9f40d6SAl Viro dentry = __lookup_hash(&nd.last, nd.path.dentry, nd.flags); 33681da177e4SLinus Torvalds if (IS_ERR(dentry)) 3369a8104a9fSAl Viro goto unlock; 3370c663e5d8SChristoph Hellwig 3371a8104a9fSAl Viro error = -EEXIST; 3372b18825a7SDavid Howells if (d_is_positive(dentry)) 3373a8104a9fSAl Viro goto fail; 3374b18825a7SDavid Howells 3375c663e5d8SChristoph Hellwig /* 3376c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3377c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3378c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3379c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3380c663e5d8SChristoph Hellwig */ 3381ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 3382a8104a9fSAl Viro error = -ENOENT; 3383ed75e95dSAl Viro goto fail; 3384e9baf6e5SAl Viro } 3385c30dabfeSJan Kara if (unlikely(err2)) { 3386c30dabfeSJan Kara error = err2; 3387a8104a9fSAl Viro goto fail; 3388c30dabfeSJan Kara } 3389ed75e95dSAl Viro *path = nd.path; 3390e9baf6e5SAl Viro return dentry; 33911da177e4SLinus Torvalds fail: 3392a8104a9fSAl Viro dput(dentry); 3393a8104a9fSAl Viro dentry = ERR_PTR(error); 3394a8104a9fSAl Viro unlock: 3395dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3396c30dabfeSJan Kara if (!err2) 3397c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 3398ed75e95dSAl Viro out: 3399dae6ad8fSAl Viro path_put(&nd.path); 3400ed75e95dSAl Viro return dentry; 3401dae6ad8fSAl Viro } 3402fa14a0b8SAl Viro 3403fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3404fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3405fa14a0b8SAl Viro { 340651689104SPaul Moore struct filename *filename = getname_kernel(pathname); 340751689104SPaul Moore struct dentry *res; 340851689104SPaul Moore 340951689104SPaul Moore if (IS_ERR(filename)) 341051689104SPaul Moore return ERR_CAST(filename); 341151689104SPaul Moore res = filename_create(dfd, filename, path, lookup_flags); 341251689104SPaul Moore putname(filename); 341351689104SPaul Moore return res; 3414fa14a0b8SAl Viro } 3415dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3416dae6ad8fSAl Viro 3417921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3418921a1650SAl Viro { 3419921a1650SAl Viro dput(dentry); 3420921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3421a8104a9fSAl Viro mnt_drop_write(path->mnt); 3422921a1650SAl Viro path_put(path); 3423921a1650SAl Viro } 3424921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3425921a1650SAl Viro 34261ac12b4bSJeff Layton struct dentry *user_path_create(int dfd, const char __user *pathname, 34271ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3428dae6ad8fSAl Viro { 342991a27b2aSJeff Layton struct filename *tmp = getname(pathname); 3430dae6ad8fSAl Viro struct dentry *res; 3431dae6ad8fSAl Viro if (IS_ERR(tmp)) 3432dae6ad8fSAl Viro return ERR_CAST(tmp); 3433fa14a0b8SAl Viro res = filename_create(dfd, tmp, path, lookup_flags); 3434dae6ad8fSAl Viro putname(tmp); 3435dae6ad8fSAl Viro return res; 3436dae6ad8fSAl Viro } 3437dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3438dae6ad8fSAl Viro 34391a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 34401da177e4SLinus Torvalds { 3441a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 34421da177e4SLinus Torvalds 34431da177e4SLinus Torvalds if (error) 34441da177e4SLinus Torvalds return error; 34451da177e4SLinus Torvalds 3446975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 34471da177e4SLinus Torvalds return -EPERM; 34481da177e4SLinus Torvalds 3449acfa4380SAl Viro if (!dir->i_op->mknod) 34501da177e4SLinus Torvalds return -EPERM; 34511da177e4SLinus Torvalds 345208ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 345308ce5f16SSerge E. Hallyn if (error) 345408ce5f16SSerge E. Hallyn return error; 345508ce5f16SSerge E. Hallyn 34561da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 34571da177e4SLinus Torvalds if (error) 34581da177e4SLinus Torvalds return error; 34591da177e4SLinus Torvalds 34601da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3461a74574aaSStephen Smalley if (!error) 3462f38aa942SAmy Griffis fsnotify_create(dir, dentry); 34631da177e4SLinus Torvalds return error; 34641da177e4SLinus Torvalds } 34654d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 34661da177e4SLinus Torvalds 3467f69aac00SAl Viro static int may_mknod(umode_t mode) 3468463c3197SDave Hansen { 3469463c3197SDave Hansen switch (mode & S_IFMT) { 3470463c3197SDave Hansen case S_IFREG: 3471463c3197SDave Hansen case S_IFCHR: 3472463c3197SDave Hansen case S_IFBLK: 3473463c3197SDave Hansen case S_IFIFO: 3474463c3197SDave Hansen case S_IFSOCK: 3475463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3476463c3197SDave Hansen return 0; 3477463c3197SDave Hansen case S_IFDIR: 3478463c3197SDave Hansen return -EPERM; 3479463c3197SDave Hansen default: 3480463c3197SDave Hansen return -EINVAL; 3481463c3197SDave Hansen } 3482463c3197SDave Hansen } 3483463c3197SDave Hansen 34848208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 34852e4d0924SHeiko Carstens unsigned, dev) 34861da177e4SLinus Torvalds { 34871da177e4SLinus Torvalds struct dentry *dentry; 3488dae6ad8fSAl Viro struct path path; 3489dae6ad8fSAl Viro int error; 3490972567f1SJeff Layton unsigned int lookup_flags = 0; 34911da177e4SLinus Torvalds 34928e4bfca1SAl Viro error = may_mknod(mode); 34938e4bfca1SAl Viro if (error) 34948e4bfca1SAl Viro return error; 3495972567f1SJeff Layton retry: 3496972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3497dae6ad8fSAl Viro if (IS_ERR(dentry)) 3498dae6ad8fSAl Viro return PTR_ERR(dentry); 34992ad94ae6SAl Viro 3500dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3501ce3b0f8dSAl Viro mode &= ~current_umask(); 3502dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3503be6d3e56SKentaro Takeda if (error) 3504a8104a9fSAl Viro goto out; 35051da177e4SLinus Torvalds switch (mode & S_IFMT) { 35061da177e4SLinus Torvalds case 0: case S_IFREG: 3507312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 35081da177e4SLinus Torvalds break; 35091da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3510dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 35111da177e4SLinus Torvalds new_decode_dev(dev)); 35121da177e4SLinus Torvalds break; 35131da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3514dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 35151da177e4SLinus Torvalds break; 35161da177e4SLinus Torvalds } 3517a8104a9fSAl Viro out: 3518921a1650SAl Viro done_path_create(&path, dentry); 3519972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3520972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3521972567f1SJeff Layton goto retry; 3522972567f1SJeff Layton } 35231da177e4SLinus Torvalds return error; 35241da177e4SLinus Torvalds } 35251da177e4SLinus Torvalds 35268208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 35275590ff0dSUlrich Drepper { 35285590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 35295590ff0dSUlrich Drepper } 35305590ff0dSUlrich Drepper 353118bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 35321da177e4SLinus Torvalds { 3533a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35348de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 35351da177e4SLinus Torvalds 35361da177e4SLinus Torvalds if (error) 35371da177e4SLinus Torvalds return error; 35381da177e4SLinus Torvalds 3539acfa4380SAl Viro if (!dir->i_op->mkdir) 35401da177e4SLinus Torvalds return -EPERM; 35411da177e4SLinus Torvalds 35421da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 35431da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 35441da177e4SLinus Torvalds if (error) 35451da177e4SLinus Torvalds return error; 35461da177e4SLinus Torvalds 35478de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 35488de52778SAl Viro return -EMLINK; 35498de52778SAl Viro 35501da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3551a74574aaSStephen Smalley if (!error) 3552f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 35531da177e4SLinus Torvalds return error; 35541da177e4SLinus Torvalds } 35554d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 35561da177e4SLinus Torvalds 3557a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 35581da177e4SLinus Torvalds { 35596902d925SDave Hansen struct dentry *dentry; 3560dae6ad8fSAl Viro struct path path; 3561dae6ad8fSAl Viro int error; 3562b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 35631da177e4SLinus Torvalds 3564b76d8b82SJeff Layton retry: 3565b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 35666902d925SDave Hansen if (IS_ERR(dentry)) 3567dae6ad8fSAl Viro return PTR_ERR(dentry); 35686902d925SDave Hansen 3569dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3570ce3b0f8dSAl Viro mode &= ~current_umask(); 3571dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3572a8104a9fSAl Viro if (!error) 3573dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3574921a1650SAl Viro done_path_create(&path, dentry); 3575b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3576b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3577b76d8b82SJeff Layton goto retry; 3578b76d8b82SJeff Layton } 35791da177e4SLinus Torvalds return error; 35801da177e4SLinus Torvalds } 35811da177e4SLinus Torvalds 3582a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 35835590ff0dSUlrich Drepper { 35845590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 35855590ff0dSUlrich Drepper } 35865590ff0dSUlrich Drepper 35871da177e4SLinus Torvalds /* 3588a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3589c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3590a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3591a71905f0SSage Weil * then we drop the dentry now. 35921da177e4SLinus Torvalds * 35931da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 35941da177e4SLinus Torvalds * do a 35951da177e4SLinus Torvalds * 35961da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 35971da177e4SLinus Torvalds * return -EBUSY; 35981da177e4SLinus Torvalds * 35991da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 36001da177e4SLinus Torvalds * that is still in use by something else.. 36011da177e4SLinus Torvalds */ 36021da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 36031da177e4SLinus Torvalds { 36041da177e4SLinus Torvalds shrink_dcache_parent(dentry); 36051da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 360698474236SWaiman Long if (dentry->d_lockref.count == 1) 36071da177e4SLinus Torvalds __d_drop(dentry); 36081da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 36091da177e4SLinus Torvalds } 36104d359507SAl Viro EXPORT_SYMBOL(dentry_unhash); 36111da177e4SLinus Torvalds 36121da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 36131da177e4SLinus Torvalds { 36141da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 36151da177e4SLinus Torvalds 36161da177e4SLinus Torvalds if (error) 36171da177e4SLinus Torvalds return error; 36181da177e4SLinus Torvalds 3619acfa4380SAl Viro if (!dir->i_op->rmdir) 36201da177e4SLinus Torvalds return -EPERM; 36211da177e4SLinus Torvalds 36221d2ef590SAl Viro dget(dentry); 36231b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3624912dbc15SSage Weil 36251da177e4SLinus Torvalds error = -EBUSY; 36267af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3627912dbc15SSage Weil goto out; 3628912dbc15SSage Weil 36291da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3630912dbc15SSage Weil if (error) 3631912dbc15SSage Weil goto out; 3632912dbc15SSage Weil 36333cebde24SSage Weil shrink_dcache_parent(dentry); 36341da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3635912dbc15SSage Weil if (error) 3636912dbc15SSage Weil goto out; 3637912dbc15SSage Weil 36381da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3639d83c49f3SAl Viro dont_mount(dentry); 36408ed936b5SEric W. Biederman detach_mounts(dentry); 36411da177e4SLinus Torvalds 3642912dbc15SSage Weil out: 3643912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 36441d2ef590SAl Viro dput(dentry); 3645912dbc15SSage Weil if (!error) 3646912dbc15SSage Weil d_delete(dentry); 36471da177e4SLinus Torvalds return error; 36481da177e4SLinus Torvalds } 36494d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 36501da177e4SLinus Torvalds 36515590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 36521da177e4SLinus Torvalds { 36531da177e4SLinus Torvalds int error = 0; 365491a27b2aSJeff Layton struct filename *name; 36551da177e4SLinus Torvalds struct dentry *dentry; 3656f5beed75SAl Viro struct path path; 3657f5beed75SAl Viro struct qstr last; 3658f5beed75SAl Viro int type; 3659c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3660c6ee9206SJeff Layton retry: 3661f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3662f5beed75SAl Viro &path, &last, &type, lookup_flags); 366391a27b2aSJeff Layton if (IS_ERR(name)) 366491a27b2aSJeff Layton return PTR_ERR(name); 36651da177e4SLinus Torvalds 3666f5beed75SAl Viro switch (type) { 36671da177e4SLinus Torvalds case LAST_DOTDOT: 36681da177e4SLinus Torvalds error = -ENOTEMPTY; 36691da177e4SLinus Torvalds goto exit1; 36701da177e4SLinus Torvalds case LAST_DOT: 36711da177e4SLinus Torvalds error = -EINVAL; 36721da177e4SLinus Torvalds goto exit1; 36731da177e4SLinus Torvalds case LAST_ROOT: 36741da177e4SLinus Torvalds error = -EBUSY; 36751da177e4SLinus Torvalds goto exit1; 36761da177e4SLinus Torvalds } 36770612d9fbSOGAWA Hirofumi 3678f5beed75SAl Viro error = mnt_want_write(path.mnt); 3679c30dabfeSJan Kara if (error) 3680c30dabfeSJan Kara goto exit1; 36810612d9fbSOGAWA Hirofumi 3682f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3683f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 36841da177e4SLinus Torvalds error = PTR_ERR(dentry); 36856902d925SDave Hansen if (IS_ERR(dentry)) 36866902d925SDave Hansen goto exit2; 3687e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3688e6bc45d6STheodore Ts'o error = -ENOENT; 3689e6bc45d6STheodore Ts'o goto exit3; 3690e6bc45d6STheodore Ts'o } 3691f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3692be6d3e56SKentaro Takeda if (error) 3693c30dabfeSJan Kara goto exit3; 3694f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 36950622753bSDave Hansen exit3: 36961da177e4SLinus Torvalds dput(dentry); 36976902d925SDave Hansen exit2: 3698f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 3699f5beed75SAl Viro mnt_drop_write(path.mnt); 37001da177e4SLinus Torvalds exit1: 3701f5beed75SAl Viro path_put(&path); 37021da177e4SLinus Torvalds putname(name); 3703c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3704c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3705c6ee9206SJeff Layton goto retry; 3706c6ee9206SJeff Layton } 37071da177e4SLinus Torvalds return error; 37081da177e4SLinus Torvalds } 37091da177e4SLinus Torvalds 37103cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 37115590ff0dSUlrich Drepper { 37125590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 37135590ff0dSUlrich Drepper } 37145590ff0dSUlrich Drepper 3715b21996e3SJ. Bruce Fields /** 3716b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3717b21996e3SJ. Bruce Fields * @dir: parent directory 3718b21996e3SJ. Bruce Fields * @dentry: victim 3719b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3720b21996e3SJ. Bruce Fields * 3721b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3722b21996e3SJ. Bruce Fields * 3723b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3724b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3725b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3726b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3727b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3728b21996e3SJ. Bruce Fields * 3729b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3730b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3731b21996e3SJ. Bruce Fields * to be NFS exported. 3732b21996e3SJ. Bruce Fields */ 3733b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 37341da177e4SLinus Torvalds { 37359accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 37361da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 37371da177e4SLinus Torvalds 37381da177e4SLinus Torvalds if (error) 37391da177e4SLinus Torvalds return error; 37401da177e4SLinus Torvalds 3741acfa4380SAl Viro if (!dir->i_op->unlink) 37421da177e4SLinus Torvalds return -EPERM; 37431da177e4SLinus Torvalds 37449accbb97SJ. Bruce Fields mutex_lock(&target->i_mutex); 37458ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 37461da177e4SLinus Torvalds error = -EBUSY; 37471da177e4SLinus Torvalds else { 37481da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3749bec1052eSAl Viro if (!error) { 37505a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 37515a14696cSJ. Bruce Fields if (error) 3752b21996e3SJ. Bruce Fields goto out; 37531da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 37548ed936b5SEric W. Biederman if (!error) { 3755d83c49f3SAl Viro dont_mount(dentry); 37568ed936b5SEric W. Biederman detach_mounts(dentry); 37578ed936b5SEric W. Biederman } 3758bec1052eSAl Viro } 37591da177e4SLinus Torvalds } 3760b21996e3SJ. Bruce Fields out: 37619accbb97SJ. Bruce Fields mutex_unlock(&target->i_mutex); 37621da177e4SLinus Torvalds 37631da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 37641da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 37659accbb97SJ. Bruce Fields fsnotify_link_count(target); 37661da177e4SLinus Torvalds d_delete(dentry); 37671da177e4SLinus Torvalds } 37680eeca283SRobert Love 37691da177e4SLinus Torvalds return error; 37701da177e4SLinus Torvalds } 37714d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 37721da177e4SLinus Torvalds 37731da177e4SLinus Torvalds /* 37741da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 37751b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 37761da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 37771da177e4SLinus Torvalds * while waiting on the I/O. 37781da177e4SLinus Torvalds */ 37795590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 37801da177e4SLinus Torvalds { 37812ad94ae6SAl Viro int error; 378291a27b2aSJeff Layton struct filename *name; 37831da177e4SLinus Torvalds struct dentry *dentry; 3784f5beed75SAl Viro struct path path; 3785f5beed75SAl Viro struct qstr last; 3786f5beed75SAl Viro int type; 37871da177e4SLinus Torvalds struct inode *inode = NULL; 3788b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 37895d18f813SJeff Layton unsigned int lookup_flags = 0; 37905d18f813SJeff Layton retry: 3791f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3792f5beed75SAl Viro &path, &last, &type, lookup_flags); 379391a27b2aSJeff Layton if (IS_ERR(name)) 379491a27b2aSJeff Layton return PTR_ERR(name); 37952ad94ae6SAl Viro 37961da177e4SLinus Torvalds error = -EISDIR; 3797f5beed75SAl Viro if (type != LAST_NORM) 37981da177e4SLinus Torvalds goto exit1; 37990612d9fbSOGAWA Hirofumi 3800f5beed75SAl Viro error = mnt_want_write(path.mnt); 3801c30dabfeSJan Kara if (error) 3802c30dabfeSJan Kara goto exit1; 3803b21996e3SJ. Bruce Fields retry_deleg: 3804f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3805f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38061da177e4SLinus Torvalds error = PTR_ERR(dentry); 38071da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 38081da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3809f5beed75SAl Viro if (last.name[last.len]) 381050338b88STörök Edwin goto slashes; 38111da177e4SLinus Torvalds inode = dentry->d_inode; 3812b18825a7SDavid Howells if (d_is_negative(dentry)) 3813e6bc45d6STheodore Ts'o goto slashes; 38147de9c6eeSAl Viro ihold(inode); 3815f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3816be6d3e56SKentaro Takeda if (error) 3817c30dabfeSJan Kara goto exit2; 3818f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 38191da177e4SLinus Torvalds exit2: 38201da177e4SLinus Torvalds dput(dentry); 38211da177e4SLinus Torvalds } 3822f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 38231da177e4SLinus Torvalds if (inode) 38241da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3825b21996e3SJ. Bruce Fields inode = NULL; 3826b21996e3SJ. Bruce Fields if (delegated_inode) { 38275a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3828b21996e3SJ. Bruce Fields if (!error) 3829b21996e3SJ. Bruce Fields goto retry_deleg; 3830b21996e3SJ. Bruce Fields } 3831f5beed75SAl Viro mnt_drop_write(path.mnt); 38321da177e4SLinus Torvalds exit1: 3833f5beed75SAl Viro path_put(&path); 38341da177e4SLinus Torvalds putname(name); 38355d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 38365d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 38375d18f813SJeff Layton inode = NULL; 38385d18f813SJeff Layton goto retry; 38395d18f813SJeff Layton } 38401da177e4SLinus Torvalds return error; 38411da177e4SLinus Torvalds 38421da177e4SLinus Torvalds slashes: 3843b18825a7SDavid Howells if (d_is_negative(dentry)) 3844b18825a7SDavid Howells error = -ENOENT; 384544b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3846b18825a7SDavid Howells error = -EISDIR; 3847b18825a7SDavid Howells else 3848b18825a7SDavid Howells error = -ENOTDIR; 38491da177e4SLinus Torvalds goto exit2; 38501da177e4SLinus Torvalds } 38511da177e4SLinus Torvalds 38522e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 38535590ff0dSUlrich Drepper { 38545590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 38555590ff0dSUlrich Drepper return -EINVAL; 38565590ff0dSUlrich Drepper 38575590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 38585590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 38595590ff0dSUlrich Drepper 38605590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 38615590ff0dSUlrich Drepper } 38625590ff0dSUlrich Drepper 38633480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 38645590ff0dSUlrich Drepper { 38655590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 38665590ff0dSUlrich Drepper } 38675590ff0dSUlrich Drepper 3868db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 38691da177e4SLinus Torvalds { 3870a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 38711da177e4SLinus Torvalds 38721da177e4SLinus Torvalds if (error) 38731da177e4SLinus Torvalds return error; 38741da177e4SLinus Torvalds 3875acfa4380SAl Viro if (!dir->i_op->symlink) 38761da177e4SLinus Torvalds return -EPERM; 38771da177e4SLinus Torvalds 38781da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 38791da177e4SLinus Torvalds if (error) 38801da177e4SLinus Torvalds return error; 38811da177e4SLinus Torvalds 38821da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3883a74574aaSStephen Smalley if (!error) 3884f38aa942SAmy Griffis fsnotify_create(dir, dentry); 38851da177e4SLinus Torvalds return error; 38861da177e4SLinus Torvalds } 38874d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 38881da177e4SLinus Torvalds 38892e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 38902e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 38911da177e4SLinus Torvalds { 38922ad94ae6SAl Viro int error; 389391a27b2aSJeff Layton struct filename *from; 38946902d925SDave Hansen struct dentry *dentry; 3895dae6ad8fSAl Viro struct path path; 3896f46d3567SJeff Layton unsigned int lookup_flags = 0; 38971da177e4SLinus Torvalds 38981da177e4SLinus Torvalds from = getname(oldname); 38991da177e4SLinus Torvalds if (IS_ERR(from)) 39001da177e4SLinus Torvalds return PTR_ERR(from); 3901f46d3567SJeff Layton retry: 3902f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 39031da177e4SLinus Torvalds error = PTR_ERR(dentry); 39046902d925SDave Hansen if (IS_ERR(dentry)) 3905dae6ad8fSAl Viro goto out_putname; 39066902d925SDave Hansen 390791a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3908a8104a9fSAl Viro if (!error) 390991a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3910921a1650SAl Viro done_path_create(&path, dentry); 3911f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 3912f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 3913f46d3567SJeff Layton goto retry; 3914f46d3567SJeff Layton } 39156902d925SDave Hansen out_putname: 39161da177e4SLinus Torvalds putname(from); 39171da177e4SLinus Torvalds return error; 39181da177e4SLinus Torvalds } 39191da177e4SLinus Torvalds 39203480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 39215590ff0dSUlrich Drepper { 39225590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 39235590ff0dSUlrich Drepper } 39245590ff0dSUlrich Drepper 3925146a8595SJ. Bruce Fields /** 3926146a8595SJ. Bruce Fields * vfs_link - create a new link 3927146a8595SJ. Bruce Fields * @old_dentry: object to be linked 3928146a8595SJ. Bruce Fields * @dir: new parent 3929146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 3930146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 3931146a8595SJ. Bruce Fields * 3932146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 3933146a8595SJ. Bruce Fields * 3934146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 3935146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 3936146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 3937146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 3938146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 3939146a8595SJ. Bruce Fields * 3940146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3941146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3942146a8595SJ. Bruce Fields * to be NFS exported. 3943146a8595SJ. Bruce Fields */ 3944146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 39451da177e4SLinus Torvalds { 39461da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 39478de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 39481da177e4SLinus Torvalds int error; 39491da177e4SLinus Torvalds 39501da177e4SLinus Torvalds if (!inode) 39511da177e4SLinus Torvalds return -ENOENT; 39521da177e4SLinus Torvalds 3953a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 39541da177e4SLinus Torvalds if (error) 39551da177e4SLinus Torvalds return error; 39561da177e4SLinus Torvalds 39571da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 39581da177e4SLinus Torvalds return -EXDEV; 39591da177e4SLinus Torvalds 39601da177e4SLinus Torvalds /* 39611da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 39621da177e4SLinus Torvalds */ 39631da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 39641da177e4SLinus Torvalds return -EPERM; 3965acfa4380SAl Viro if (!dir->i_op->link) 39661da177e4SLinus Torvalds return -EPERM; 39677e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 39681da177e4SLinus Torvalds return -EPERM; 39691da177e4SLinus Torvalds 39701da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 39711da177e4SLinus Torvalds if (error) 39721da177e4SLinus Torvalds return error; 39731da177e4SLinus Torvalds 39747e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 3975aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 3976f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 3977aae8a97dSAneesh Kumar K.V error = -ENOENT; 39788de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 39798de52778SAl Viro error = -EMLINK; 3980146a8595SJ. Bruce Fields else { 3981146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 3982146a8595SJ. Bruce Fields if (!error) 39831da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 3984146a8595SJ. Bruce Fields } 3985f4e0c30cSAl Viro 3986f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 3987f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3988f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 3989f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3990f4e0c30cSAl Viro } 39917e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 3992e31e14ecSStephen Smalley if (!error) 39937e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 39941da177e4SLinus Torvalds return error; 39951da177e4SLinus Torvalds } 39964d359507SAl Viro EXPORT_SYMBOL(vfs_link); 39971da177e4SLinus Torvalds 39981da177e4SLinus Torvalds /* 39991da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 40001da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 40011da177e4SLinus Torvalds * newname. --KAB 40021da177e4SLinus Torvalds * 40031da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 40041da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 40051da177e4SLinus Torvalds * and other special files. --ADM 40061da177e4SLinus Torvalds */ 40072e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 40082e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 40091da177e4SLinus Torvalds { 40101da177e4SLinus Torvalds struct dentry *new_dentry; 4011dae6ad8fSAl Viro struct path old_path, new_path; 4012146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 401311a7b371SAneesh Kumar K.V int how = 0; 40141da177e4SLinus Torvalds int error; 40151da177e4SLinus Torvalds 401611a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4017c04030e1SUlrich Drepper return -EINVAL; 401811a7b371SAneesh Kumar K.V /* 4019f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4020f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4021f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 402211a7b371SAneesh Kumar K.V */ 4023f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4024f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4025f0cc6ffbSLinus Torvalds return -ENOENT; 402611a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4027f0cc6ffbSLinus Torvalds } 4028c04030e1SUlrich Drepper 402911a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 403011a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4031442e31caSJeff Layton retry: 403211a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 40331da177e4SLinus Torvalds if (error) 40342ad94ae6SAl Viro return error; 40352ad94ae6SAl Viro 4036442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4037442e31caSJeff Layton (how & LOOKUP_REVAL)); 40381da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 40396902d925SDave Hansen if (IS_ERR(new_dentry)) 4040dae6ad8fSAl Viro goto out; 4041dae6ad8fSAl Viro 4042dae6ad8fSAl Viro error = -EXDEV; 4043dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4044dae6ad8fSAl Viro goto out_dput; 4045800179c9SKees Cook error = may_linkat(&old_path); 4046800179c9SKees Cook if (unlikely(error)) 4047800179c9SKees Cook goto out_dput; 4048dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4049be6d3e56SKentaro Takeda if (error) 4050a8104a9fSAl Viro goto out_dput; 4051146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 405275c3f29dSDave Hansen out_dput: 4053921a1650SAl Viro done_path_create(&new_path, new_dentry); 4054146a8595SJ. Bruce Fields if (delegated_inode) { 4055146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4056d22e6338SOleg Drokin if (!error) { 4057d22e6338SOleg Drokin path_put(&old_path); 4058146a8595SJ. Bruce Fields goto retry; 4059146a8595SJ. Bruce Fields } 4060d22e6338SOleg Drokin } 4061442e31caSJeff Layton if (retry_estale(error, how)) { 4062d22e6338SOleg Drokin path_put(&old_path); 4063442e31caSJeff Layton how |= LOOKUP_REVAL; 4064442e31caSJeff Layton goto retry; 4065442e31caSJeff Layton } 40661da177e4SLinus Torvalds out: 40672d8f3038SAl Viro path_put(&old_path); 40681da177e4SLinus Torvalds 40691da177e4SLinus Torvalds return error; 40701da177e4SLinus Torvalds } 40711da177e4SLinus Torvalds 40723480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 40735590ff0dSUlrich Drepper { 4074c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 40755590ff0dSUlrich Drepper } 40765590ff0dSUlrich Drepper 4077bc27027aSMiklos Szeredi /** 4078bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4079bc27027aSMiklos Szeredi * @old_dir: parent of source 4080bc27027aSMiklos Szeredi * @old_dentry: source 4081bc27027aSMiklos Szeredi * @new_dir: parent of destination 4082bc27027aSMiklos Szeredi * @new_dentry: destination 4083bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4084520c8b16SMiklos Szeredi * @flags: rename flags 4085bc27027aSMiklos Szeredi * 4086bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4087bc27027aSMiklos Szeredi * 4088bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4089bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4090bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4091bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4092bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4093bc27027aSMiklos Szeredi * so. 4094bc27027aSMiklos Szeredi * 4095bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4096bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4097bc27027aSMiklos Szeredi * to be NFS exported. 4098bc27027aSMiklos Szeredi * 40991da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 41001da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 41011da177e4SLinus Torvalds * Problems: 4102d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 41031da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 41041da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4105a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 41061da177e4SLinus Torvalds * story. 41076cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 41086cedba89SJ. Bruce Fields * and source (if it is not a directory). 41091b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 41101da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 41111da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4112a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 41131da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 41141da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 41151da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4116a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 41171da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 41181da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 41191da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4120e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 41211b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 41221da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4123c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 41241da177e4SLinus Torvalds * locking]. 41251da177e4SLinus Torvalds */ 41261da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 41278e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4128520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 41291da177e4SLinus Torvalds { 41301da177e4SLinus Torvalds int error; 4131bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 413259b0df21SEric Paris const unsigned char *old_name; 4133bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4134bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4135da1ce067SMiklos Szeredi bool new_is_dir = false; 4136da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 41371da177e4SLinus Torvalds 4138bc27027aSMiklos Szeredi if (source == target) 41391da177e4SLinus Torvalds return 0; 41401da177e4SLinus Torvalds 41411da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 41421da177e4SLinus Torvalds if (error) 41431da177e4SLinus Torvalds return error; 41441da177e4SLinus Torvalds 4145da1ce067SMiklos Szeredi if (!target) { 4146a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4147da1ce067SMiklos Szeredi } else { 4148da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4149da1ce067SMiklos Szeredi 4150da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 41511da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4152da1ce067SMiklos Szeredi else 4153da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4154da1ce067SMiklos Szeredi } 41551da177e4SLinus Torvalds if (error) 41561da177e4SLinus Torvalds return error; 41571da177e4SLinus Torvalds 41587177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 41591da177e4SLinus Torvalds return -EPERM; 41601da177e4SLinus Torvalds 4161520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4162520c8b16SMiklos Szeredi return -EINVAL; 4163520c8b16SMiklos Szeredi 4164bc27027aSMiklos Szeredi /* 4165bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4166bc27027aSMiklos Szeredi * we'll need to flip '..'. 4167bc27027aSMiklos Szeredi */ 4168da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4169da1ce067SMiklos Szeredi if (is_dir) { 4170bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4171bc27027aSMiklos Szeredi if (error) 4172bc27027aSMiklos Szeredi return error; 4173bc27027aSMiklos Szeredi } 4174da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4175da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4176da1ce067SMiklos Szeredi if (error) 4177da1ce067SMiklos Szeredi return error; 4178da1ce067SMiklos Szeredi } 4179da1ce067SMiklos Szeredi } 41800eeca283SRobert Love 41810b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 41820b3974ebSMiklos Szeredi flags); 4183bc27027aSMiklos Szeredi if (error) 4184bc27027aSMiklos Szeredi return error; 4185bc27027aSMiklos Szeredi 4186bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4187bc27027aSMiklos Szeredi dget(new_dentry); 4188da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4189bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4190bc27027aSMiklos Szeredi else if (target) 4191bc27027aSMiklos Szeredi mutex_lock(&target->i_mutex); 4192bc27027aSMiklos Szeredi 4193bc27027aSMiklos Szeredi error = -EBUSY; 41947af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4195bc27027aSMiklos Szeredi goto out; 4196bc27027aSMiklos Szeredi 4197da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4198bc27027aSMiklos Szeredi error = -EMLINK; 4199da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4200bc27027aSMiklos Szeredi goto out; 4201da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4202da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4203da1ce067SMiklos Szeredi goto out; 4204da1ce067SMiklos Szeredi } 4205da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4206bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4207da1ce067SMiklos Szeredi if (!is_dir) { 4208bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4209bc27027aSMiklos Szeredi if (error) 4210bc27027aSMiklos Szeredi goto out; 4211da1ce067SMiklos Szeredi } 4212da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4213bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4214bc27027aSMiklos Szeredi if (error) 4215bc27027aSMiklos Szeredi goto out; 4216bc27027aSMiklos Szeredi } 42177177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4218520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4219520c8b16SMiklos Szeredi new_dir, new_dentry); 4220520c8b16SMiklos Szeredi } else { 42217177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4222520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4223520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4224520c8b16SMiklos Szeredi } 4225bc27027aSMiklos Szeredi if (error) 4226bc27027aSMiklos Szeredi goto out; 4227bc27027aSMiklos Szeredi 4228da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 42291da177e4SLinus Torvalds if (is_dir) 4230bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4231bc27027aSMiklos Szeredi dont_mount(new_dentry); 42328ed936b5SEric W. Biederman detach_mounts(new_dentry); 4233bc27027aSMiklos Szeredi } 4234da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4235da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4236bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4237da1ce067SMiklos Szeredi else 4238da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4239da1ce067SMiklos Szeredi } 4240bc27027aSMiklos Szeredi out: 4241da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4242bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4243bc27027aSMiklos Szeredi else if (target) 4244bc27027aSMiklos Szeredi mutex_unlock(&target->i_mutex); 4245bc27027aSMiklos Szeredi dput(new_dentry); 4246da1ce067SMiklos Szeredi if (!error) { 4247123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4248da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4249da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4250da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4251da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4252da1ce067SMiklos Szeredi } 4253da1ce067SMiklos Szeredi } 42540eeca283SRobert Love fsnotify_oldname_free(old_name); 42550eeca283SRobert Love 42561da177e4SLinus Torvalds return error; 42571da177e4SLinus Torvalds } 42584d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 42591da177e4SLinus Torvalds 4260520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4261520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 42621da177e4SLinus Torvalds { 42631da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 42641da177e4SLinus Torvalds struct dentry *trap; 4265f5beed75SAl Viro struct path old_path, new_path; 4266f5beed75SAl Viro struct qstr old_last, new_last; 4267f5beed75SAl Viro int old_type, new_type; 42688e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 426991a27b2aSJeff Layton struct filename *from; 427091a27b2aSJeff Layton struct filename *to; 4271f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4272c6a94284SJeff Layton bool should_retry = false; 42732ad94ae6SAl Viro int error; 4274520c8b16SMiklos Szeredi 42750d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4276da1ce067SMiklos Szeredi return -EINVAL; 4277da1ce067SMiklos Szeredi 42780d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 42790d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4280520c8b16SMiklos Szeredi return -EINVAL; 4281520c8b16SMiklos Szeredi 42820d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 42830d7a8555SMiklos Szeredi return -EPERM; 42840d7a8555SMiklos Szeredi 4285f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4286f5beed75SAl Viro target_flags = 0; 4287f5beed75SAl Viro 4288c6a94284SJeff Layton retry: 4289f5beed75SAl Viro from = user_path_parent(olddfd, oldname, 4290f5beed75SAl Viro &old_path, &old_last, &old_type, lookup_flags); 429191a27b2aSJeff Layton if (IS_ERR(from)) { 429291a27b2aSJeff Layton error = PTR_ERR(from); 42931da177e4SLinus Torvalds goto exit; 429491a27b2aSJeff Layton } 42951da177e4SLinus Torvalds 4296f5beed75SAl Viro to = user_path_parent(newdfd, newname, 4297f5beed75SAl Viro &new_path, &new_last, &new_type, lookup_flags); 429891a27b2aSJeff Layton if (IS_ERR(to)) { 429991a27b2aSJeff Layton error = PTR_ERR(to); 43001da177e4SLinus Torvalds goto exit1; 430191a27b2aSJeff Layton } 43021da177e4SLinus Torvalds 43031da177e4SLinus Torvalds error = -EXDEV; 4304f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 43051da177e4SLinus Torvalds goto exit2; 43061da177e4SLinus Torvalds 43071da177e4SLinus Torvalds error = -EBUSY; 4308f5beed75SAl Viro if (old_type != LAST_NORM) 43091da177e4SLinus Torvalds goto exit2; 43101da177e4SLinus Torvalds 43110a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 43120a7c3937SMiklos Szeredi error = -EEXIST; 4313f5beed75SAl Viro if (new_type != LAST_NORM) 43141da177e4SLinus Torvalds goto exit2; 43151da177e4SLinus Torvalds 4316f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4317c30dabfeSJan Kara if (error) 4318c30dabfeSJan Kara goto exit2; 4319c30dabfeSJan Kara 43208e6d782cSJ. Bruce Fields retry_deleg: 4321f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 43221da177e4SLinus Torvalds 4323f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 43241da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 43251da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 43261da177e4SLinus Torvalds goto exit3; 43271da177e4SLinus Torvalds /* source must exist */ 43281da177e4SLinus Torvalds error = -ENOENT; 4329b18825a7SDavid Howells if (d_is_negative(old_dentry)) 43301da177e4SLinus Torvalds goto exit4; 4331f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 43321da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 43331da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 43341da177e4SLinus Torvalds goto exit4; 43350a7c3937SMiklos Szeredi error = -EEXIST; 43360a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 43370a7c3937SMiklos Szeredi goto exit5; 4338da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4339da1ce067SMiklos Szeredi error = -ENOENT; 4340da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4341da1ce067SMiklos Szeredi goto exit5; 4342da1ce067SMiklos Szeredi 4343da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4344da1ce067SMiklos Szeredi error = -ENOTDIR; 4345f5beed75SAl Viro if (new_last.name[new_last.len]) 4346da1ce067SMiklos Szeredi goto exit5; 4347da1ce067SMiklos Szeredi } 4348da1ce067SMiklos Szeredi } 43490a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 43500a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 43510a7c3937SMiklos Szeredi error = -ENOTDIR; 4352f5beed75SAl Viro if (old_last.name[old_last.len]) 43530a7c3937SMiklos Szeredi goto exit5; 4354f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 43550a7c3937SMiklos Szeredi goto exit5; 43560a7c3937SMiklos Szeredi } 43570a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 43580a7c3937SMiklos Szeredi error = -EINVAL; 43590a7c3937SMiklos Szeredi if (old_dentry == trap) 43600a7c3937SMiklos Szeredi goto exit5; 43611da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4362da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43631da177e4SLinus Torvalds error = -ENOTEMPTY; 43641da177e4SLinus Torvalds if (new_dentry == trap) 43651da177e4SLinus Torvalds goto exit5; 43661da177e4SLinus Torvalds 4367f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4368f5beed75SAl Viro &new_path, new_dentry, flags); 4369be6d3e56SKentaro Takeda if (error) 4370c30dabfeSJan Kara goto exit5; 4371f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4372f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4373520c8b16SMiklos Szeredi &delegated_inode, flags); 43741da177e4SLinus Torvalds exit5: 43751da177e4SLinus Torvalds dput(new_dentry); 43761da177e4SLinus Torvalds exit4: 43771da177e4SLinus Torvalds dput(old_dentry); 43781da177e4SLinus Torvalds exit3: 4379f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 43808e6d782cSJ. Bruce Fields if (delegated_inode) { 43818e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 43828e6d782cSJ. Bruce Fields if (!error) 43838e6d782cSJ. Bruce Fields goto retry_deleg; 43848e6d782cSJ. Bruce Fields } 4385f5beed75SAl Viro mnt_drop_write(old_path.mnt); 43861da177e4SLinus Torvalds exit2: 4387c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4388c6a94284SJeff Layton should_retry = true; 4389f5beed75SAl Viro path_put(&new_path); 43902ad94ae6SAl Viro putname(to); 43911da177e4SLinus Torvalds exit1: 4392f5beed75SAl Viro path_put(&old_path); 43931da177e4SLinus Torvalds putname(from); 4394c6a94284SJeff Layton if (should_retry) { 4395c6a94284SJeff Layton should_retry = false; 4396c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4397c6a94284SJeff Layton goto retry; 4398c6a94284SJeff Layton } 43992ad94ae6SAl Viro exit: 44001da177e4SLinus Torvalds return error; 44011da177e4SLinus Torvalds } 44021da177e4SLinus Torvalds 4403520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4404520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4405520c8b16SMiklos Szeredi { 4406520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4407520c8b16SMiklos Szeredi } 4408520c8b16SMiklos Szeredi 4409a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 44105590ff0dSUlrich Drepper { 4411520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 44125590ff0dSUlrich Drepper } 44135590ff0dSUlrich Drepper 4414787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4415787fb6bcSMiklos Szeredi { 4416787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4417787fb6bcSMiklos Szeredi if (error) 4418787fb6bcSMiklos Szeredi return error; 4419787fb6bcSMiklos Szeredi 4420787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4421787fb6bcSMiklos Szeredi return -EPERM; 4422787fb6bcSMiklos Szeredi 4423787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4424787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4425787fb6bcSMiklos Szeredi } 4426787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4427787fb6bcSMiklos Szeredi 44285d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 44291da177e4SLinus Torvalds { 44305d826c84SAl Viro int len = PTR_ERR(link); 44311da177e4SLinus Torvalds if (IS_ERR(link)) 44321da177e4SLinus Torvalds goto out; 44331da177e4SLinus Torvalds 44341da177e4SLinus Torvalds len = strlen(link); 44351da177e4SLinus Torvalds if (len > (unsigned) buflen) 44361da177e4SLinus Torvalds len = buflen; 44371da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 44381da177e4SLinus Torvalds len = -EFAULT; 44391da177e4SLinus Torvalds out: 44401da177e4SLinus Torvalds return len; 44411da177e4SLinus Torvalds } 44425d826c84SAl Viro EXPORT_SYMBOL(readlink_copy); 44431da177e4SLinus Torvalds 44441da177e4SLinus Torvalds /* 44451da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 44461da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 44471da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 44481da177e4SLinus Torvalds */ 44491da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44501da177e4SLinus Torvalds { 4451cc314eefSLinus Torvalds void *cookie; 4452d4dee48bSAl Viro const char *link = dentry->d_inode->i_link; 4453694a1764SMarcin Slusarz int res; 4454cc314eefSLinus Torvalds 4455d4dee48bSAl Viro if (!link) { 4456d4dee48bSAl Viro link = dentry->d_inode->i_op->follow_link(dentry, &cookie, NULL); 4457680baacbSAl Viro if (IS_ERR(link)) 4458680baacbSAl Viro return PTR_ERR(link); 4459d4dee48bSAl Viro } 4460680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 4461680baacbSAl Viro if (cookie && dentry->d_inode->i_op->put_link) 4462680baacbSAl Viro dentry->d_inode->i_op->put_link(dentry, cookie); 4463694a1764SMarcin Slusarz return res; 44641da177e4SLinus Torvalds } 44654d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 44661da177e4SLinus Torvalds 44671da177e4SLinus Torvalds /* get the link contents into pagecache */ 44681da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 44691da177e4SLinus Torvalds { 4470ebd09abbSDuane Griffin char *kaddr; 44711da177e4SLinus Torvalds struct page *page; 44721da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 4473090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 44741da177e4SLinus Torvalds if (IS_ERR(page)) 44756fe6900eSNick Piggin return (char*)page; 44761da177e4SLinus Torvalds *ppage = page; 4477ebd09abbSDuane Griffin kaddr = kmap(page); 4478ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 4479ebd09abbSDuane Griffin return kaddr; 44801da177e4SLinus Torvalds } 44811da177e4SLinus Torvalds 44821da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44831da177e4SLinus Torvalds { 44841da177e4SLinus Torvalds struct page *page = NULL; 44855d826c84SAl Viro int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); 44861da177e4SLinus Torvalds if (page) { 44871da177e4SLinus Torvalds kunmap(page); 44881da177e4SLinus Torvalds page_cache_release(page); 44891da177e4SLinus Torvalds } 44901da177e4SLinus Torvalds return res; 44911da177e4SLinus Torvalds } 44924d359507SAl Viro EXPORT_SYMBOL(page_readlink); 44931da177e4SLinus Torvalds 4494680baacbSAl Viro const char *page_follow_link_light(struct dentry *dentry, void **cookie, struct nameidata *nd) 44951da177e4SLinus Torvalds { 4496cc314eefSLinus Torvalds struct page *page = NULL; 4497680baacbSAl Viro char *res = page_getlink(dentry, &page); 4498680baacbSAl Viro if (!IS_ERR(res)) 4499680baacbSAl Viro *cookie = page; 4500680baacbSAl Viro return res; 45011da177e4SLinus Torvalds } 45024d359507SAl Viro EXPORT_SYMBOL(page_follow_link_light); 45031da177e4SLinus Torvalds 4504680baacbSAl Viro void page_put_link(struct dentry *dentry, void *cookie) 45051da177e4SLinus Torvalds { 4506cc314eefSLinus Torvalds struct page *page = cookie; 45071da177e4SLinus Torvalds kunmap(page); 45081da177e4SLinus Torvalds page_cache_release(page); 45091da177e4SLinus Torvalds } 45104d359507SAl Viro EXPORT_SYMBOL(page_put_link); 45111da177e4SLinus Torvalds 451254566b2cSNick Piggin /* 451354566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 451454566b2cSNick Piggin */ 451554566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 45161da177e4SLinus Torvalds { 45171da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 45180adb25d2SKirill Korotaev struct page *page; 4519afddba49SNick Piggin void *fsdata; 4520beb497abSDmitriy Monakhov int err; 45211da177e4SLinus Torvalds char *kaddr; 452254566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 452354566b2cSNick Piggin if (nofs) 452454566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 45251da177e4SLinus Torvalds 45267e53cac4SNeilBrown retry: 4527afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 452854566b2cSNick Piggin flags, &page, &fsdata); 45291da177e4SLinus Torvalds if (err) 4530afddba49SNick Piggin goto fail; 4531afddba49SNick Piggin 4532e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 45331da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 4534e8e3c3d6SCong Wang kunmap_atomic(kaddr); 4535afddba49SNick Piggin 4536afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4537afddba49SNick Piggin page, fsdata); 45381da177e4SLinus Torvalds if (err < 0) 45391da177e4SLinus Torvalds goto fail; 4540afddba49SNick Piggin if (err < len-1) 4541afddba49SNick Piggin goto retry; 4542afddba49SNick Piggin 45431da177e4SLinus Torvalds mark_inode_dirty(inode); 45441da177e4SLinus Torvalds return 0; 45451da177e4SLinus Torvalds fail: 45461da177e4SLinus Torvalds return err; 45471da177e4SLinus Torvalds } 45484d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 45491da177e4SLinus Torvalds 45500adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 45510adb25d2SKirill Korotaev { 45520adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 455354566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 45540adb25d2SKirill Korotaev } 45554d359507SAl Viro EXPORT_SYMBOL(page_symlink); 45560adb25d2SKirill Korotaev 455792e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 45581da177e4SLinus Torvalds .readlink = generic_readlink, 45591da177e4SLinus Torvalds .follow_link = page_follow_link_light, 45601da177e4SLinus Torvalds .put_link = page_put_link, 45611da177e4SLinus Torvalds }; 45621da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4563