11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namei.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Some corrections by tytso. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 121da177e4SLinus Torvalds * lookup logic. 131da177e4SLinus Torvalds */ 141da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 151da177e4SLinus Torvalds */ 161da177e4SLinus Torvalds 171da177e4SLinus Torvalds #include <linux/init.h> 18630d9c47SPaul Gortmaker #include <linux/export.h> 1944696908SDavid S. Miller #include <linux/kernel.h> 201da177e4SLinus Torvalds #include <linux/slab.h> 211da177e4SLinus Torvalds #include <linux/fs.h> 221da177e4SLinus Torvalds #include <linux/namei.h> 231da177e4SLinus Torvalds #include <linux/pagemap.h> 240eeca283SRobert Love #include <linux/fsnotify.h> 251da177e4SLinus Torvalds #include <linux/personality.h> 261da177e4SLinus Torvalds #include <linux/security.h> 276146f0d5SMimi Zohar #include <linux/ima.h> 281da177e4SLinus Torvalds #include <linux/syscalls.h> 291da177e4SLinus Torvalds #include <linux/mount.h> 301da177e4SLinus Torvalds #include <linux/audit.h> 3116f7e0feSRandy Dunlap #include <linux/capability.h> 32834f2a4aSTrond Myklebust #include <linux/file.h> 335590ff0dSUlrich Drepper #include <linux/fcntl.h> 3408ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 355ad4e53bSAl Viro #include <linux/fs_struct.h> 36e77819e5SLinus Torvalds #include <linux/posix_acl.h> 3799d263d4SLinus Torvalds #include <linux/hash.h> 381da177e4SLinus Torvalds #include <asm/uaccess.h> 391da177e4SLinus Torvalds 40e81e3f4dSEric Paris #include "internal.h" 41c7105365SAl Viro #include "mount.h" 42e81e3f4dSEric Paris 431da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 441da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 451da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 461da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 471da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 481da177e4SLinus Torvalds * 491da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 501da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 511da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 521da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 531da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 541da177e4SLinus Torvalds * the special cases of the former code. 551da177e4SLinus Torvalds * 561da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 571da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 581da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 591da177e4SLinus Torvalds * 601da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 611da177e4SLinus Torvalds * resolution to correspond with current state of the code. 621da177e4SLinus Torvalds * 631da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 641da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 651da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 661da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 671da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 681da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 691da177e4SLinus Torvalds */ 701da177e4SLinus Torvalds 711da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 721da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 731da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 741da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 751da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 761da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7725985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 781da177e4SLinus Torvalds * 791da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 801da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 811da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 821da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 831da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 841da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 851da177e4SLinus Torvalds * and in the old Linux semantics. 861da177e4SLinus Torvalds */ 871da177e4SLinus Torvalds 881da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 891da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 901da177e4SLinus Torvalds * 911da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 921da177e4SLinus Torvalds */ 931da177e4SLinus Torvalds 941da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 951da177e4SLinus Torvalds * inside the path - always follow. 961da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 971da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 981da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 991da177e4SLinus Torvalds * otherwise - don't follow. 1001da177e4SLinus Torvalds * (applied in that order). 1011da177e4SLinus Torvalds * 1021da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1031da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1041da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1051da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1061da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1071da177e4SLinus Torvalds */ 1081da177e4SLinus Torvalds /* 1091da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 110a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1111da177e4SLinus Torvalds * any extra contention... 1121da177e4SLinus Torvalds */ 1131da177e4SLinus Torvalds 1141da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1151da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1161da177e4SLinus Torvalds * kernel data space before using them.. 1171da177e4SLinus Torvalds * 1181da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1191da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1201da177e4SLinus Torvalds */ 1217950e385SJeff Layton 122fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12391a27b2aSJeff Layton 12451f39a1fSDavid Drysdale struct filename * 12591a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12691a27b2aSJeff Layton { 12794b5d262SAl Viro struct filename *result; 1287950e385SJeff Layton char *kname; 12994b5d262SAl Viro int len; 1301da177e4SLinus Torvalds 1317ac86265SJeff Layton result = audit_reusename(filename); 1327ac86265SJeff Layton if (result) 1337ac86265SJeff Layton return result; 1347ac86265SJeff Layton 1357950e385SJeff Layton result = __getname(); 1363f9f0aa6SLinus Torvalds if (unlikely(!result)) 1374043cde8SEric Paris return ERR_PTR(-ENOMEM); 1381da177e4SLinus Torvalds 1397950e385SJeff Layton /* 1407950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1417950e385SJeff Layton * allocation 1427950e385SJeff Layton */ 143fd2f7cb5SAl Viro kname = (char *)result->iname; 14491a27b2aSJeff Layton result->name = kname; 1457950e385SJeff Layton 14694b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 14791a27b2aSJeff Layton if (unlikely(len < 0)) { 14894b5d262SAl Viro __putname(result); 14994b5d262SAl Viro return ERR_PTR(len); 15091a27b2aSJeff Layton } 1513f9f0aa6SLinus Torvalds 1527950e385SJeff Layton /* 1537950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1547950e385SJeff Layton * separate struct filename so we can dedicate the entire 1557950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1567950e385SJeff Layton * userland. 1577950e385SJeff Layton */ 15894b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 159fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1607950e385SJeff Layton kname = (char *)result; 1617950e385SJeff Layton 162fd2f7cb5SAl Viro /* 163fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 164fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 165fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 166fd2f7cb5SAl Viro */ 167fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 16894b5d262SAl Viro if (unlikely(!result)) { 16994b5d262SAl Viro __putname(kname); 17094b5d262SAl Viro return ERR_PTR(-ENOMEM); 1717950e385SJeff Layton } 1727950e385SJeff Layton result->name = kname; 17394b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17494b5d262SAl Viro if (unlikely(len < 0)) { 17594b5d262SAl Viro __putname(kname); 17694b5d262SAl Viro kfree(result); 17794b5d262SAl Viro return ERR_PTR(len); 17894b5d262SAl Viro } 17994b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18094b5d262SAl Viro __putname(kname); 18194b5d262SAl Viro kfree(result); 18294b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18394b5d262SAl Viro } 1847950e385SJeff Layton } 1857950e385SJeff Layton 18694b5d262SAl Viro result->refcnt = 1; 1873f9f0aa6SLinus Torvalds /* The empty path is special. */ 1883f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1893f9f0aa6SLinus Torvalds if (empty) 1901fa1e7f6SAndy Whitcroft *empty = 1; 19194b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19294b5d262SAl Viro putname(result); 19394b5d262SAl Viro return ERR_PTR(-ENOENT); 1941da177e4SLinus Torvalds } 19594b5d262SAl Viro } 1967950e385SJeff Layton 1977950e385SJeff Layton result->uptr = filename; 198c4ad8f98SLinus Torvalds result->aname = NULL; 1991da177e4SLinus Torvalds audit_getname(result); 2001da177e4SLinus Torvalds return result; 2013f9f0aa6SLinus Torvalds } 2023f9f0aa6SLinus Torvalds 20391a27b2aSJeff Layton struct filename * 20491a27b2aSJeff Layton getname(const char __user * filename) 205f52e0c11SAl Viro { 206f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 207f52e0c11SAl Viro } 208f52e0c11SAl Viro 209c4ad8f98SLinus Torvalds struct filename * 210c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 211c4ad8f98SLinus Torvalds { 212c4ad8f98SLinus Torvalds struct filename *result; 21308518549SPaul Moore int len = strlen(filename) + 1; 214c4ad8f98SLinus Torvalds 215c4ad8f98SLinus Torvalds result = __getname(); 216c4ad8f98SLinus Torvalds if (unlikely(!result)) 217c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 218c4ad8f98SLinus Torvalds 21908518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 220fd2f7cb5SAl Viro result->name = (char *)result->iname; 22108518549SPaul Moore } else if (len <= PATH_MAX) { 22208518549SPaul Moore struct filename *tmp; 22308518549SPaul Moore 22408518549SPaul Moore tmp = kmalloc(sizeof(*tmp), GFP_KERNEL); 22508518549SPaul Moore if (unlikely(!tmp)) { 22608518549SPaul Moore __putname(result); 22708518549SPaul Moore return ERR_PTR(-ENOMEM); 22808518549SPaul Moore } 22908518549SPaul Moore tmp->name = (char *)result; 23008518549SPaul Moore result = tmp; 23108518549SPaul Moore } else { 23208518549SPaul Moore __putname(result); 23308518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23408518549SPaul Moore } 23508518549SPaul Moore memcpy((char *)result->name, filename, len); 236c4ad8f98SLinus Torvalds result->uptr = NULL; 237c4ad8f98SLinus Torvalds result->aname = NULL; 23855422d0bSPaul Moore result->refcnt = 1; 239fd3522fdSPaul Moore audit_getname(result); 240c4ad8f98SLinus Torvalds 241c4ad8f98SLinus Torvalds return result; 242c4ad8f98SLinus Torvalds } 243c4ad8f98SLinus Torvalds 24491a27b2aSJeff Layton void putname(struct filename *name) 2451da177e4SLinus Torvalds { 24655422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 24755422d0bSPaul Moore 24855422d0bSPaul Moore if (--name->refcnt > 0) 24955422d0bSPaul Moore return; 25055422d0bSPaul Moore 251fd2f7cb5SAl Viro if (name->name != name->iname) { 25255422d0bSPaul Moore __putname(name->name); 25355422d0bSPaul Moore kfree(name); 25455422d0bSPaul Moore } else 25555422d0bSPaul Moore __putname(name); 2561da177e4SLinus Torvalds } 2571da177e4SLinus Torvalds 258e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 259e77819e5SLinus Torvalds { 26084635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 261e77819e5SLinus Torvalds struct posix_acl *acl; 262e77819e5SLinus Torvalds 263e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2643567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2653567866bSAl Viro if (!acl) 266e77819e5SLinus Torvalds return -EAGAIN; 2673567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 2683567866bSAl Viro if (acl == ACL_NOT_CACHED) 269e77819e5SLinus Torvalds return -ECHILD; 270206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 271e77819e5SLinus Torvalds } 272e77819e5SLinus Torvalds 2732982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2744e34e719SChristoph Hellwig if (IS_ERR(acl)) 2754e34e719SChristoph Hellwig return PTR_ERR(acl); 276e77819e5SLinus Torvalds if (acl) { 277e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 278e77819e5SLinus Torvalds posix_acl_release(acl); 279e77819e5SLinus Torvalds return error; 280e77819e5SLinus Torvalds } 28184635d68SLinus Torvalds #endif 282e77819e5SLinus Torvalds 283e77819e5SLinus Torvalds return -EAGAIN; 284e77819e5SLinus Torvalds } 285e77819e5SLinus Torvalds 2865909ccaaSLinus Torvalds /* 287948409c7SAndreas Gruenbacher * This does the basic permission checking 2885909ccaaSLinus Torvalds */ 2897e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2905909ccaaSLinus Torvalds { 29126cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2925909ccaaSLinus Torvalds 2938e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2945909ccaaSLinus Torvalds mode >>= 6; 2955909ccaaSLinus Torvalds else { 296e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2977e40145eSAl Viro int error = check_acl(inode, mask); 2985909ccaaSLinus Torvalds if (error != -EAGAIN) 2995909ccaaSLinus Torvalds return error; 3005909ccaaSLinus Torvalds } 3015909ccaaSLinus Torvalds 3025909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3035909ccaaSLinus Torvalds mode >>= 3; 3045909ccaaSLinus Torvalds } 3055909ccaaSLinus Torvalds 3065909ccaaSLinus Torvalds /* 3075909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3085909ccaaSLinus Torvalds */ 3099c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3105909ccaaSLinus Torvalds return 0; 3115909ccaaSLinus Torvalds return -EACCES; 3125909ccaaSLinus Torvalds } 3131da177e4SLinus Torvalds 3141da177e4SLinus Torvalds /** 3151da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3161da177e4SLinus Torvalds * @inode: inode to check access rights for 3178fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3181da177e4SLinus Torvalds * 3191da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3201da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3211da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 322b74c79e9SNick Piggin * are used for other things. 323b74c79e9SNick Piggin * 324b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 325b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 326b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3271da177e4SLinus Torvalds */ 3282830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3291da177e4SLinus Torvalds { 3305909ccaaSLinus Torvalds int ret; 3311da177e4SLinus Torvalds 3321da177e4SLinus Torvalds /* 333948409c7SAndreas Gruenbacher * Do the basic permission checks. 3341da177e4SLinus Torvalds */ 3357e40145eSAl Viro ret = acl_permission_check(inode, mask); 3365909ccaaSLinus Torvalds if (ret != -EACCES) 3375909ccaaSLinus Torvalds return ret; 3381da177e4SLinus Torvalds 339d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 340d594e7ecSAl Viro /* DACs are overridable for directories */ 34123adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 342d594e7ecSAl Viro return 0; 343d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34423adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34523adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 346d594e7ecSAl Viro return 0; 347d594e7ecSAl Viro return -EACCES; 348d594e7ecSAl Viro } 3491da177e4SLinus Torvalds /* 3501da177e4SLinus Torvalds * Read/write DACs are always overridable. 351d594e7ecSAl Viro * Executable DACs are overridable when there is 352d594e7ecSAl Viro * at least one exec bit set. 3531da177e4SLinus Torvalds */ 354d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 35523adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3561da177e4SLinus Torvalds return 0; 3571da177e4SLinus Torvalds 3581da177e4SLinus Torvalds /* 3591da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3601da177e4SLinus Torvalds */ 3617ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 362d594e7ecSAl Viro if (mask == MAY_READ) 36323adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3641da177e4SLinus Torvalds return 0; 3651da177e4SLinus Torvalds 3661da177e4SLinus Torvalds return -EACCES; 3671da177e4SLinus Torvalds } 3684d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3691da177e4SLinus Torvalds 3703ddcd056SLinus Torvalds /* 3713ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3723ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3733ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3743ddcd056SLinus Torvalds * permission function, use the fast case". 3753ddcd056SLinus Torvalds */ 3763ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3773ddcd056SLinus Torvalds { 3783ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3793ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3803ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3813ddcd056SLinus Torvalds 3823ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3833ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3843ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3853ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3863ddcd056SLinus Torvalds } 3873ddcd056SLinus Torvalds return generic_permission(inode, mask); 3883ddcd056SLinus Torvalds } 3893ddcd056SLinus Torvalds 390cb23beb5SChristoph Hellwig /** 3910bdaea90SDavid Howells * __inode_permission - Check for access rights to a given inode 3920bdaea90SDavid Howells * @inode: Inode to check permission on 3930bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 394cb23beb5SChristoph Hellwig * 3950bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. 396948409c7SAndreas Gruenbacher * 397948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 3980bdaea90SDavid Howells * 3990bdaea90SDavid Howells * This does not check for a read-only file system. You probably want 4000bdaea90SDavid Howells * inode_permission(). 401cb23beb5SChristoph Hellwig */ 4020bdaea90SDavid Howells int __inode_permission(struct inode *inode, int mask) 4031da177e4SLinus Torvalds { 404e6305c43SAl Viro int retval; 4051da177e4SLinus Torvalds 4063ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 4071da177e4SLinus Torvalds /* 4081da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 4091da177e4SLinus Torvalds */ 4101da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 4111da177e4SLinus Torvalds return -EACCES; 4121da177e4SLinus Torvalds } 4131da177e4SLinus Torvalds 4143ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 4151da177e4SLinus Torvalds if (retval) 4161da177e4SLinus Torvalds return retval; 4171da177e4SLinus Torvalds 41808ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 41908ce5f16SSerge E. Hallyn if (retval) 42008ce5f16SSerge E. Hallyn return retval; 42108ce5f16SSerge E. Hallyn 422d09ca739SEric Paris return security_inode_permission(inode, mask); 4231da177e4SLinus Torvalds } 424bd5d0856SMiklos Szeredi EXPORT_SYMBOL(__inode_permission); 4251da177e4SLinus Torvalds 426f4d6ff89SAl Viro /** 4270bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 4280bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 42955852635SRandy Dunlap * @inode: Inode to check permission on 4300bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4310bdaea90SDavid Howells * 4320bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4330bdaea90SDavid Howells */ 4340bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4350bdaea90SDavid Howells { 4360bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4370bdaea90SDavid Howells umode_t mode = inode->i_mode; 4380bdaea90SDavid Howells 4390bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 4400bdaea90SDavid Howells if ((sb->s_flags & MS_RDONLY) && 4410bdaea90SDavid Howells (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4420bdaea90SDavid Howells return -EROFS; 4430bdaea90SDavid Howells } 4440bdaea90SDavid Howells return 0; 4450bdaea90SDavid Howells } 4460bdaea90SDavid Howells 4470bdaea90SDavid Howells /** 4480bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4490bdaea90SDavid Howells * @inode: Inode to check permission on 4500bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4510bdaea90SDavid Howells * 4520bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4530bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4540bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4550bdaea90SDavid Howells * 4560bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4570bdaea90SDavid Howells */ 4580bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4590bdaea90SDavid Howells { 4600bdaea90SDavid Howells int retval; 4610bdaea90SDavid Howells 4620bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4630bdaea90SDavid Howells if (retval) 4640bdaea90SDavid Howells return retval; 4650bdaea90SDavid Howells return __inode_permission(inode, mask); 4660bdaea90SDavid Howells } 4674d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4680bdaea90SDavid Howells 4690bdaea90SDavid Howells /** 4705dd784d0SJan Blunck * path_get - get a reference to a path 4715dd784d0SJan Blunck * @path: path to get the reference to 4725dd784d0SJan Blunck * 4735dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4745dd784d0SJan Blunck */ 475dcf787f3SAl Viro void path_get(const struct path *path) 4765dd784d0SJan Blunck { 4775dd784d0SJan Blunck mntget(path->mnt); 4785dd784d0SJan Blunck dget(path->dentry); 4795dd784d0SJan Blunck } 4805dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4815dd784d0SJan Blunck 4825dd784d0SJan Blunck /** 4831d957f9bSJan Blunck * path_put - put a reference to a path 4841d957f9bSJan Blunck * @path: path to put the reference to 4851d957f9bSJan Blunck * 4861d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4871d957f9bSJan Blunck */ 488dcf787f3SAl Viro void path_put(const struct path *path) 4891da177e4SLinus Torvalds { 4901d957f9bSJan Blunck dput(path->dentry); 4911d957f9bSJan Blunck mntput(path->mnt); 4921da177e4SLinus Torvalds } 4931d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4941da177e4SLinus Torvalds 495894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 4961f55a6ecSAl Viro struct nameidata { 4971f55a6ecSAl Viro struct path path; 4981f55a6ecSAl Viro struct qstr last; 4991f55a6ecSAl Viro struct path root; 5001f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 5011f55a6ecSAl Viro unsigned int flags; 5029883d185SAl Viro unsigned seq, m_seq; 5031f55a6ecSAl Viro int last_type; 5041f55a6ecSAl Viro unsigned depth; 505756daf26SNeilBrown int total_link_count; 506697fc6caSAl Viro struct saved { 507697fc6caSAl Viro struct path link; 508fceef393SAl Viro struct delayed_call done; 509697fc6caSAl Viro const char *name; 5100450b2d1SAl Viro unsigned seq; 511894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5129883d185SAl Viro struct filename *name; 5139883d185SAl Viro struct nameidata *saved; 514fceef393SAl Viro struct inode *link_inode; 5159883d185SAl Viro unsigned root_seq; 5169883d185SAl Viro int dfd; 5171f55a6ecSAl Viro }; 5181f55a6ecSAl Viro 5199883d185SAl Viro static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) 520894bc8c4SAl Viro { 521756daf26SNeilBrown struct nameidata *old = current->nameidata; 522756daf26SNeilBrown p->stack = p->internal; 523c8a53ee5SAl Viro p->dfd = dfd; 524c8a53ee5SAl Viro p->name = name; 525756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 5269883d185SAl Viro p->saved = old; 527756daf26SNeilBrown current->nameidata = p; 528894bc8c4SAl Viro } 529894bc8c4SAl Viro 5309883d185SAl Viro static void restore_nameidata(void) 531894bc8c4SAl Viro { 5329883d185SAl Viro struct nameidata *now = current->nameidata, *old = now->saved; 533756daf26SNeilBrown 534756daf26SNeilBrown current->nameidata = old; 535756daf26SNeilBrown if (old) 536756daf26SNeilBrown old->total_link_count = now->total_link_count; 537756daf26SNeilBrown if (now->stack != now->internal) { 538756daf26SNeilBrown kfree(now->stack); 539756daf26SNeilBrown now->stack = now->internal; 540894bc8c4SAl Viro } 541894bc8c4SAl Viro } 542894bc8c4SAl Viro 543894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 544894bc8c4SAl Viro { 545bc40aee0SAl Viro struct saved *p; 546bc40aee0SAl Viro 547bc40aee0SAl Viro if (nd->flags & LOOKUP_RCU) { 548bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 549bc40aee0SAl Viro GFP_ATOMIC); 550bc40aee0SAl Viro if (unlikely(!p)) 551bc40aee0SAl Viro return -ECHILD; 552bc40aee0SAl Viro } else { 553bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 554894bc8c4SAl Viro GFP_KERNEL); 555894bc8c4SAl Viro if (unlikely(!p)) 556894bc8c4SAl Viro return -ENOMEM; 557bc40aee0SAl Viro } 558894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 559894bc8c4SAl Viro nd->stack = p; 560894bc8c4SAl Viro return 0; 561894bc8c4SAl Viro } 562894bc8c4SAl Viro 563397d425dSEric W. Biederman /** 564397d425dSEric W. Biederman * path_connected - Verify that a path->dentry is below path->mnt.mnt_root 565397d425dSEric W. Biederman * @path: nameidate to verify 566397d425dSEric W. Biederman * 567397d425dSEric W. Biederman * Rename can sometimes move a file or directory outside of a bind 568397d425dSEric W. Biederman * mount, path_connected allows those cases to be detected. 569397d425dSEric W. Biederman */ 570397d425dSEric W. Biederman static bool path_connected(const struct path *path) 571397d425dSEric W. Biederman { 572397d425dSEric W. Biederman struct vfsmount *mnt = path->mnt; 573397d425dSEric W. Biederman 574397d425dSEric W. Biederman /* Only bind mounts can have disconnected paths */ 575397d425dSEric W. Biederman if (mnt->mnt_root == mnt->mnt_sb->s_root) 576397d425dSEric W. Biederman return true; 577397d425dSEric W. Biederman 578397d425dSEric W. Biederman return is_subdir(path->dentry, mnt->mnt_root); 579397d425dSEric W. Biederman } 580397d425dSEric W. Biederman 581894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 582894bc8c4SAl Viro { 583da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 584894bc8c4SAl Viro return 0; 585894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 586894bc8c4SAl Viro return 0; 587894bc8c4SAl Viro return __nd_alloc_stack(nd); 588894bc8c4SAl Viro } 589894bc8c4SAl Viro 5907973387aSAl Viro static void drop_links(struct nameidata *nd) 5917973387aSAl Viro { 5927973387aSAl Viro int i = nd->depth; 5937973387aSAl Viro while (i--) { 5947973387aSAl Viro struct saved *last = nd->stack + i; 595fceef393SAl Viro do_delayed_call(&last->done); 596fceef393SAl Viro clear_delayed_call(&last->done); 5977973387aSAl Viro } 5987973387aSAl Viro } 5997973387aSAl Viro 6007973387aSAl Viro static void terminate_walk(struct nameidata *nd) 6017973387aSAl Viro { 6027973387aSAl Viro drop_links(nd); 6037973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 6047973387aSAl Viro int i; 6057973387aSAl Viro path_put(&nd->path); 6067973387aSAl Viro for (i = 0; i < nd->depth; i++) 6077973387aSAl Viro path_put(&nd->stack[i].link); 608102b8af2SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 609102b8af2SAl Viro path_put(&nd->root); 610102b8af2SAl Viro nd->root.mnt = NULL; 611102b8af2SAl Viro } 6127973387aSAl Viro } else { 6137973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 6147973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6157973387aSAl Viro nd->root.mnt = NULL; 6167973387aSAl Viro rcu_read_unlock(); 6177973387aSAl Viro } 6187973387aSAl Viro nd->depth = 0; 6197973387aSAl Viro } 6207973387aSAl Viro 6217973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 6227973387aSAl Viro static bool legitimize_path(struct nameidata *nd, 6237973387aSAl Viro struct path *path, unsigned seq) 6247973387aSAl Viro { 6257973387aSAl Viro int res = __legitimize_mnt(path->mnt, nd->m_seq); 6267973387aSAl Viro if (unlikely(res)) { 6277973387aSAl Viro if (res > 0) 6287973387aSAl Viro path->mnt = NULL; 6297973387aSAl Viro path->dentry = NULL; 6307973387aSAl Viro return false; 6317973387aSAl Viro } 6327973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 6337973387aSAl Viro path->dentry = NULL; 6347973387aSAl Viro return false; 6357973387aSAl Viro } 6367973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6377973387aSAl Viro } 6387973387aSAl Viro 6397973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6407973387aSAl Viro { 6417973387aSAl Viro int i; 6427973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6437973387aSAl Viro struct saved *last = nd->stack + i; 6447973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6457973387aSAl Viro drop_links(nd); 6467973387aSAl Viro nd->depth = i + 1; 6477973387aSAl Viro return false; 6487973387aSAl Viro } 6497973387aSAl Viro } 6507973387aSAl Viro return true; 6517973387aSAl Viro } 6527973387aSAl Viro 65319660af7SAl Viro /* 65431e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 65519660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 65619660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 65719660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 65819660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 65919660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 66019660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 66119660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 66231e6b01fSNick Piggin */ 66331e6b01fSNick Piggin 66431e6b01fSNick Piggin /** 66519660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 66619660af7SAl Viro * @nd: nameidata pathwalk data 66719660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 6686e9918b7SAl Viro * @seq: seq number to check dentry against 66939191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 67031e6b01fSNick Piggin * 67119660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 67219660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 67319660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 6747973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6757973387aSAl Viro * terminate_walk(). 67631e6b01fSNick Piggin */ 6776e9918b7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry, unsigned seq) 67831e6b01fSNick Piggin { 67931e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 68031e6b01fSNick Piggin 68131e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 682e5c832d5SLinus Torvalds 683e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6847973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6857973387aSAl Viro goto out2; 6867973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 6877973387aSAl Viro goto out2; 6887973387aSAl Viro if (unlikely(!lockref_get_not_dead(&parent->d_lockref))) 6897973387aSAl Viro goto out1; 69048a066e7SAl Viro 69115570086SLinus Torvalds /* 69215570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 69315570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 69415570086SLinus Torvalds * 69515570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 69615570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 69715570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 69815570086SLinus Torvalds * since we checked the sequence number of the parent after we got 69915570086SLinus Torvalds * the child sequence number. So we know the parent must still 70015570086SLinus Torvalds * be valid if the child sequence number is still valid. 70115570086SLinus Torvalds */ 70219660af7SAl Viro if (!dentry) { 703e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 704e5c832d5SLinus Torvalds goto out; 70519660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 70619660af7SAl Viro } else { 707e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 708e5c832d5SLinus Torvalds goto out; 7096e9918b7SAl Viro if (read_seqcount_retry(&dentry->d_seq, seq)) 710e5c832d5SLinus Torvalds goto drop_dentry; 71119660af7SAl Viro } 712e5c832d5SLinus Torvalds 713e5c832d5SLinus Torvalds /* 714e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 715e5c832d5SLinus Torvalds * still valid and get it if required. 716e5c832d5SLinus Torvalds */ 717e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 7185a8d87e8SAl Viro if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq))) { 7195a8d87e8SAl Viro rcu_read_unlock(); 7205a8d87e8SAl Viro dput(dentry); 7215a8d87e8SAl Viro return -ECHILD; 7227973387aSAl Viro } 72331e6b01fSNick Piggin } 72431e6b01fSNick Piggin 7258b61e74fSAl Viro rcu_read_unlock(); 72631e6b01fSNick Piggin return 0; 72719660af7SAl Viro 728e5c832d5SLinus Torvalds drop_dentry: 7298b61e74fSAl Viro rcu_read_unlock(); 730e5c832d5SLinus Torvalds dput(dentry); 731d0d27277SLinus Torvalds goto drop_root_mnt; 7327973387aSAl Viro out2: 7337973387aSAl Viro nd->path.mnt = NULL; 7347973387aSAl Viro out1: 7357973387aSAl Viro nd->path.dentry = NULL; 736e5c832d5SLinus Torvalds out: 7378b61e74fSAl Viro rcu_read_unlock(); 738d0d27277SLinus Torvalds drop_root_mnt: 739d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 740d0d27277SLinus Torvalds nd->root.mnt = NULL; 74131e6b01fSNick Piggin return -ECHILD; 74231e6b01fSNick Piggin } 74331e6b01fSNick Piggin 7447973387aSAl Viro static int unlazy_link(struct nameidata *nd, struct path *link, unsigned seq) 7457973387aSAl Viro { 7467973387aSAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 7477973387aSAl Viro drop_links(nd); 7487973387aSAl Viro nd->depth = 0; 7497973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 7507973387aSAl Viro nd->path.mnt = NULL; 7517973387aSAl Viro nd->path.dentry = NULL; 7527973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7537973387aSAl Viro nd->root.mnt = NULL; 7547973387aSAl Viro rcu_read_unlock(); 7557973387aSAl Viro } else if (likely(unlazy_walk(nd, NULL, 0)) == 0) { 7567973387aSAl Viro return 0; 7577973387aSAl Viro } 7587973387aSAl Viro path_put(link); 7597973387aSAl Viro return -ECHILD; 7607973387aSAl Viro } 7617973387aSAl Viro 7624ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 76334286d66SNick Piggin { 7644ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 76534286d66SNick Piggin } 76634286d66SNick Piggin 7679f1fafeeSAl Viro /** 7689f1fafeeSAl Viro * complete_walk - successful completion of path walk 7699f1fafeeSAl Viro * @nd: pointer nameidata 77039159de2SJeff Layton * 7719f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7729f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7739f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7749f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7759f1fafeeSAl Viro * need to drop nd->path. 77639159de2SJeff Layton */ 7779f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 77839159de2SJeff Layton { 77916c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 78039159de2SJeff Layton int status; 78139159de2SJeff Layton 7829f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 7839f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7849f1fafeeSAl Viro nd->root.mnt = NULL; 7856e9918b7SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 78648a066e7SAl Viro return -ECHILD; 78748a066e7SAl Viro } 7889f1fafeeSAl Viro 78916c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 79039159de2SJeff Layton return 0; 79139159de2SJeff Layton 792ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 79316c2cd71SAl Viro return 0; 79416c2cd71SAl Viro 795ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 79639159de2SJeff Layton if (status > 0) 79739159de2SJeff Layton return 0; 79839159de2SJeff Layton 79916c2cd71SAl Viro if (!status) 80039159de2SJeff Layton status = -ESTALE; 80116c2cd71SAl Viro 80239159de2SJeff Layton return status; 80339159de2SJeff Layton } 80439159de2SJeff Layton 80518d8c860SAl Viro static void set_root(struct nameidata *nd) 8062a737871SAl Viro { 807f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 8082a737871SAl Viro } 8092a737871SAl Viro 81006d7137eSAl Viro static void set_root_rcu(struct nameidata *nd) 81131e6b01fSNick Piggin { 81231e6b01fSNick Piggin struct fs_struct *fs = current->fs; 8138f47a016SAl Viro unsigned seq; 814c28cc364SNick Piggin 815c28cc364SNick Piggin do { 816c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 81731e6b01fSNick Piggin nd->root = fs->root; 8188f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 819c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 82031e6b01fSNick Piggin } 82131e6b01fSNick Piggin 8221d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 823051d3812SIan Kent { 824051d3812SIan Kent dput(path->dentry); 8254ac91378SJan Blunck if (path->mnt != nd->path.mnt) 826051d3812SIan Kent mntput(path->mnt); 827051d3812SIan Kent } 828051d3812SIan Kent 8297b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8307b9337aaSNick Piggin struct nameidata *nd) 831051d3812SIan Kent { 83231e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8334ac91378SJan Blunck dput(nd->path.dentry); 83431e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8354ac91378SJan Blunck mntput(nd->path.mnt); 8369a229683SHuang Shijie } 83731e6b01fSNick Piggin nd->path.mnt = path->mnt; 8384ac91378SJan Blunck nd->path.dentry = path->dentry; 839051d3812SIan Kent } 840051d3812SIan Kent 841b5fb63c1SChristoph Hellwig /* 8426b255391SAl Viro * Helper to directly jump to a known parsed path from ->get_link, 843b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 844b5fb63c1SChristoph Hellwig */ 8456e77137bSAl Viro void nd_jump_link(struct path *path) 846b5fb63c1SChristoph Hellwig { 8476e77137bSAl Viro struct nameidata *nd = current->nameidata; 848b5fb63c1SChristoph Hellwig path_put(&nd->path); 849b5fb63c1SChristoph Hellwig 850b5fb63c1SChristoph Hellwig nd->path = *path; 851b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 852b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 853b5fb63c1SChristoph Hellwig } 854b5fb63c1SChristoph Hellwig 855b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 856574197e0SAl Viro { 85721c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 858fceef393SAl Viro do_delayed_call(&last->done); 8596548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 860b9ff4429SAl Viro path_put(&last->link); 861574197e0SAl Viro } 862574197e0SAl Viro 863561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 864561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 865800179c9SKees Cook 866800179c9SKees Cook /** 867800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 86855852635SRandy Dunlap * @nd: nameidata pathwalk data 869800179c9SKees Cook * 870800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 871800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 872800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 873800179c9SKees Cook * processes from failing races against path names that may change out 874800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 875800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 876800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 877800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 878800179c9SKees Cook * 879800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 880800179c9SKees Cook */ 881fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 882800179c9SKees Cook { 883800179c9SKees Cook const struct inode *inode; 884800179c9SKees Cook const struct inode *parent; 885800179c9SKees Cook 886800179c9SKees Cook if (!sysctl_protected_symlinks) 887800179c9SKees Cook return 0; 888800179c9SKees Cook 889800179c9SKees Cook /* Allowed if owner and follower match. */ 890fceef393SAl Viro inode = nd->link_inode; 89181abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 892800179c9SKees Cook return 0; 893800179c9SKees Cook 894800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 895aa65fa35SAl Viro parent = nd->inode; 896800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 897800179c9SKees Cook return 0; 898800179c9SKees Cook 899800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 90081abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 901800179c9SKees Cook return 0; 902800179c9SKees Cook 90331956502SAl Viro if (nd->flags & LOOKUP_RCU) 90431956502SAl Viro return -ECHILD; 90531956502SAl Viro 9061cf2665bSAl Viro audit_log_link_denied("follow_link", &nd->stack[0].link); 907800179c9SKees Cook return -EACCES; 908800179c9SKees Cook } 909800179c9SKees Cook 910800179c9SKees Cook /** 911800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 912800179c9SKees Cook * @inode: the source inode to hardlink from 913800179c9SKees Cook * 914800179c9SKees Cook * Return false if at least one of the following conditions: 915800179c9SKees Cook * - inode is not a regular file 916800179c9SKees Cook * - inode is setuid 917800179c9SKees Cook * - inode is setgid and group-exec 918800179c9SKees Cook * - access failure for read and write 919800179c9SKees Cook * 920800179c9SKees Cook * Otherwise returns true. 921800179c9SKees Cook */ 922800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 923800179c9SKees Cook { 924800179c9SKees Cook umode_t mode = inode->i_mode; 925800179c9SKees Cook 926800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 927800179c9SKees Cook if (!S_ISREG(mode)) 928800179c9SKees Cook return false; 929800179c9SKees Cook 930800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 931800179c9SKees Cook if (mode & S_ISUID) 932800179c9SKees Cook return false; 933800179c9SKees Cook 934800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 935800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 936800179c9SKees Cook return false; 937800179c9SKees Cook 938800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 939800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 940800179c9SKees Cook return false; 941800179c9SKees Cook 942800179c9SKees Cook return true; 943800179c9SKees Cook } 944800179c9SKees Cook 945800179c9SKees Cook /** 946800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 947800179c9SKees Cook * @link: the source to hardlink from 948800179c9SKees Cook * 949800179c9SKees Cook * Block hardlink when all of: 950800179c9SKees Cook * - sysctl_protected_hardlinks enabled 951800179c9SKees Cook * - fsuid does not match inode 952800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 953f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 954800179c9SKees Cook * 955800179c9SKees Cook * Returns 0 if successful, -ve on error. 956800179c9SKees Cook */ 957800179c9SKees Cook static int may_linkat(struct path *link) 958800179c9SKees Cook { 959800179c9SKees Cook struct inode *inode; 960800179c9SKees Cook 961800179c9SKees Cook if (!sysctl_protected_hardlinks) 962800179c9SKees Cook return 0; 963800179c9SKees Cook 964800179c9SKees Cook inode = link->dentry->d_inode; 965800179c9SKees Cook 966800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 967800179c9SKees Cook * otherwise, it must be a safe source. 968800179c9SKees Cook */ 969f2ca3796SDirk Steinmetz if (inode_owner_or_capable(inode) || safe_hardlink_source(inode)) 970800179c9SKees Cook return 0; 971800179c9SKees Cook 972a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 973800179c9SKees Cook return -EPERM; 974800179c9SKees Cook } 975800179c9SKees Cook 9763b2e7f75SAl Viro static __always_inline 9773b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 9781da177e4SLinus Torvalds { 979ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 9801cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 981fceef393SAl Viro struct inode *inode = nd->link_inode; 9826d7b5aaeSAl Viro int error; 9830a959df5SAl Viro const char *res; 9841da177e4SLinus Torvalds 9858fa9dd24SNeilBrown if (!(nd->flags & LOOKUP_RCU)) { 9868fa9dd24SNeilBrown touch_atime(&last->link); 9878fa9dd24SNeilBrown cond_resched(); 9888fa9dd24SNeilBrown } else if (atime_needs_update(&last->link, inode)) { 9898fa9dd24SNeilBrown if (unlikely(unlazy_walk(nd, NULL, 0))) 9908fa9dd24SNeilBrown return ERR_PTR(-ECHILD); 9918fa9dd24SNeilBrown touch_atime(&last->link); 9928fa9dd24SNeilBrown } 9938fa9dd24SNeilBrown 994bda0be7aSNeilBrown error = security_inode_follow_link(dentry, inode, 995bda0be7aSNeilBrown nd->flags & LOOKUP_RCU); 996bda0be7aSNeilBrown if (unlikely(error)) 9976920a440SAl Viro return ERR_PTR(error); 99836f3b4f6SAl Viro 99986acdca1SAl Viro nd->last_type = LAST_BIND; 1000d4dee48bSAl Viro res = inode->i_link; 1001d4dee48bSAl Viro if (!res) { 1002fceef393SAl Viro const char * (*get)(struct dentry *, struct inode *, 1003fceef393SAl Viro struct delayed_call *); 1004fceef393SAl Viro get = inode->i_op->get_link; 10058c1b4566SAl Viro if (nd->flags & LOOKUP_RCU) { 1006fceef393SAl Viro res = get(NULL, inode, &last->done); 10076b255391SAl Viro if (res == ERR_PTR(-ECHILD)) { 10088c1b4566SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 10098c1b4566SAl Viro return ERR_PTR(-ECHILD); 1010fceef393SAl Viro res = get(dentry, inode, &last->done); 10118c1b4566SAl Viro } 10126b255391SAl Viro } else { 1013fceef393SAl Viro res = get(dentry, inode, &last->done); 10146b255391SAl Viro } 1015fceef393SAl Viro if (IS_ERR_OR_NULL(res)) 1016fab51e8aSAl Viro return res; 10170a959df5SAl Viro } 1018fab51e8aSAl Viro if (*res == '/') { 10198c1b4566SAl Viro if (nd->flags & LOOKUP_RCU) { 10208f47a016SAl Viro struct dentry *d; 10218f47a016SAl Viro if (!nd->root.mnt) 10228f47a016SAl Viro set_root_rcu(nd); 10238f47a016SAl Viro nd->path = nd->root; 10248f47a016SAl Viro d = nd->path.dentry; 10258f47a016SAl Viro nd->inode = d->d_inode; 10268f47a016SAl Viro nd->seq = nd->root_seq; 10278f47a016SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 10288c1b4566SAl Viro return ERR_PTR(-ECHILD); 10298f47a016SAl Viro } else { 1030fab51e8aSAl Viro if (!nd->root.mnt) 1031fab51e8aSAl Viro set_root(nd); 1032fab51e8aSAl Viro path_put(&nd->path); 1033fab51e8aSAl Viro nd->path = nd->root; 1034fab51e8aSAl Viro path_get(&nd->root); 1035fab51e8aSAl Viro nd->inode = nd->path.dentry->d_inode; 10368f47a016SAl Viro } 1037fab51e8aSAl Viro nd->flags |= LOOKUP_JUMPED; 1038fab51e8aSAl Viro while (unlikely(*++res == '/')) 1039fab51e8aSAl Viro ; 1040fab51e8aSAl Viro } 1041fab51e8aSAl Viro if (!*res) 1042fab51e8aSAl Viro res = NULL; 10430a959df5SAl Viro return res; 10440a959df5SAl Viro } 10456d7b5aaeSAl Viro 1046f015f126SDavid Howells /* 1047f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1048f015f126SDavid Howells * 1049f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1050f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1051f015f126SDavid Howells * Up is towards /. 1052f015f126SDavid Howells * 1053f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1054f015f126SDavid Howells * root. 1055f015f126SDavid Howells */ 1056bab77ebfSAl Viro int follow_up(struct path *path) 10571da177e4SLinus Torvalds { 10580714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 10590714a533SAl Viro struct mount *parent; 10601da177e4SLinus Torvalds struct dentry *mountpoint; 106199b7db7bSNick Piggin 106248a066e7SAl Viro read_seqlock_excl(&mount_lock); 10630714a533SAl Viro parent = mnt->mnt_parent; 10643c0a6163SAl Viro if (parent == mnt) { 106548a066e7SAl Viro read_sequnlock_excl(&mount_lock); 10661da177e4SLinus Torvalds return 0; 10671da177e4SLinus Torvalds } 10680714a533SAl Viro mntget(&parent->mnt); 1069a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 107048a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1071bab77ebfSAl Viro dput(path->dentry); 1072bab77ebfSAl Viro path->dentry = mountpoint; 1073bab77ebfSAl Viro mntput(path->mnt); 10740714a533SAl Viro path->mnt = &parent->mnt; 10751da177e4SLinus Torvalds return 1; 10761da177e4SLinus Torvalds } 10774d359507SAl Viro EXPORT_SYMBOL(follow_up); 10781da177e4SLinus Torvalds 1079b5c84bf6SNick Piggin /* 10809875cf80SDavid Howells * Perform an automount 10819875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 10829875cf80SDavid Howells * were called with. 10831da177e4SLinus Torvalds */ 1084756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 10859875cf80SDavid Howells bool *need_mntput) 108631e6b01fSNick Piggin { 10879875cf80SDavid Howells struct vfsmount *mnt; 1088ea5b778aSDavid Howells int err; 10899875cf80SDavid Howells 10909875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 10919875cf80SDavid Howells return -EREMOTE; 10929875cf80SDavid Howells 10930ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 10940ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 10950ec26fd0SMiklos Szeredi * the name. 10960ec26fd0SMiklos Szeredi * 10970ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 10985a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 10990ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 11000ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 11010ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 11020ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 11035a30d8a2SDavid Howells */ 1104756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 1105d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 11065a30d8a2SDavid Howells path->dentry->d_inode) 11079875cf80SDavid Howells return -EISDIR; 11080ec26fd0SMiklos Szeredi 1109756daf26SNeilBrown nd->total_link_count++; 1110756daf26SNeilBrown if (nd->total_link_count >= 40) 11119875cf80SDavid Howells return -ELOOP; 11129875cf80SDavid Howells 11139875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 11149875cf80SDavid Howells if (IS_ERR(mnt)) { 11159875cf80SDavid Howells /* 11169875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 11179875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 11189875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 11199875cf80SDavid Howells * 11209875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 11219875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 11229875cf80SDavid Howells * the path is inaccessible and we should say so. 11239875cf80SDavid Howells */ 1124756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 11259875cf80SDavid Howells return -EREMOTE; 11269875cf80SDavid Howells return PTR_ERR(mnt); 112731e6b01fSNick Piggin } 1128ea5b778aSDavid Howells 11299875cf80SDavid Howells if (!mnt) /* mount collision */ 11309875cf80SDavid Howells return 0; 11319875cf80SDavid Howells 11328aef1884SAl Viro if (!*need_mntput) { 11338aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 11348aef1884SAl Viro mntget(path->mnt); 11358aef1884SAl Viro *need_mntput = true; 11368aef1884SAl Viro } 113719a167afSAl Viro err = finish_automount(mnt, path); 1138ea5b778aSDavid Howells 1139ea5b778aSDavid Howells switch (err) { 1140ea5b778aSDavid Howells case -EBUSY: 1141ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 114219a167afSAl Viro return 0; 1143ea5b778aSDavid Howells case 0: 11448aef1884SAl Viro path_put(path); 11459875cf80SDavid Howells path->mnt = mnt; 11469875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 11479875cf80SDavid Howells return 0; 114819a167afSAl Viro default: 114919a167afSAl Viro return err; 11509875cf80SDavid Howells } 115119a167afSAl Viro 1152ea5b778aSDavid Howells } 11539875cf80SDavid Howells 11549875cf80SDavid Howells /* 11559875cf80SDavid Howells * Handle a dentry that is managed in some way. 1156cc53ce53SDavid Howells * - Flagged for transit management (autofs) 11579875cf80SDavid Howells * - Flagged as mountpoint 11589875cf80SDavid Howells * - Flagged as automount point 11599875cf80SDavid Howells * 11609875cf80SDavid Howells * This may only be called in refwalk mode. 11619875cf80SDavid Howells * 11629875cf80SDavid Howells * Serialization is taken care of in namespace.c 11639875cf80SDavid Howells */ 1164756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 11659875cf80SDavid Howells { 11668aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 11679875cf80SDavid Howells unsigned managed; 11689875cf80SDavid Howells bool need_mntput = false; 11698aef1884SAl Viro int ret = 0; 11709875cf80SDavid Howells 11719875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 11729875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 11739875cf80SDavid Howells * the components of that value change under us */ 11749875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 11759875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 11769875cf80SDavid Howells unlikely(managed != 0)) { 1177cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1178cc53ce53SDavid Howells * being held. */ 1179cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1180cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1181cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 11821aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1183cc53ce53SDavid Howells if (ret < 0) 11848aef1884SAl Viro break; 1185cc53ce53SDavid Howells } 1186cc53ce53SDavid Howells 11879875cf80SDavid Howells /* Transit to a mounted filesystem. */ 11889875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 11899875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 11909875cf80SDavid Howells if (mounted) { 11919875cf80SDavid Howells dput(path->dentry); 11929875cf80SDavid Howells if (need_mntput) 1193463ffb2eSAl Viro mntput(path->mnt); 1194463ffb2eSAl Viro path->mnt = mounted; 1195463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 11969875cf80SDavid Howells need_mntput = true; 11979875cf80SDavid Howells continue; 1198463ffb2eSAl Viro } 1199463ffb2eSAl Viro 12009875cf80SDavid Howells /* Something is mounted on this dentry in another 12019875cf80SDavid Howells * namespace and/or whatever was mounted there in this 120248a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 120348a066e7SAl Viro * get it */ 12041da177e4SLinus Torvalds } 12059875cf80SDavid Howells 12069875cf80SDavid Howells /* Handle an automount point */ 12079875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1208756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 12099875cf80SDavid Howells if (ret < 0) 12108aef1884SAl Viro break; 12119875cf80SDavid Howells continue; 12129875cf80SDavid Howells } 12139875cf80SDavid Howells 12149875cf80SDavid Howells /* We didn't change the current path point */ 12159875cf80SDavid Howells break; 12169875cf80SDavid Howells } 12178aef1884SAl Viro 12188aef1884SAl Viro if (need_mntput && path->mnt == mnt) 12198aef1884SAl Viro mntput(path->mnt); 12208aef1884SAl Viro if (ret == -EISDIR) 12218aef1884SAl Viro ret = 0; 12228402752eSAl Viro if (need_mntput) 12238402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 12248402752eSAl Viro if (unlikely(ret < 0)) 12258402752eSAl Viro path_put_conditional(path, nd); 12268402752eSAl Viro return ret; 12271da177e4SLinus Torvalds } 12281da177e4SLinus Torvalds 1229cc53ce53SDavid Howells int follow_down_one(struct path *path) 12301da177e4SLinus Torvalds { 12311da177e4SLinus Torvalds struct vfsmount *mounted; 12321da177e4SLinus Torvalds 12331c755af4SAl Viro mounted = lookup_mnt(path); 12341da177e4SLinus Torvalds if (mounted) { 12359393bd07SAl Viro dput(path->dentry); 12369393bd07SAl Viro mntput(path->mnt); 12379393bd07SAl Viro path->mnt = mounted; 12389393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12391da177e4SLinus Torvalds return 1; 12401da177e4SLinus Torvalds } 12411da177e4SLinus Torvalds return 0; 12421da177e4SLinus Torvalds } 12434d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12441da177e4SLinus Torvalds 1245b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 124662a7375eSIan Kent { 1247b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1248b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 124962a7375eSIan Kent } 125062a7375eSIan Kent 12519875cf80SDavid Howells /* 1252287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1253287548e4SAl Viro * we meet a managed dentry that would need blocking. 12549875cf80SDavid Howells */ 12559875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1256254cf582SAl Viro struct inode **inode, unsigned *seqp) 12579875cf80SDavid Howells { 125862a7375eSIan Kent for (;;) { 1259c7105365SAl Viro struct mount *mounted; 126062a7375eSIan Kent /* 126162a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 126262a7375eSIan Kent * that wants to block transit. 126362a7375eSIan Kent */ 1264b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1265b8faf035SNeilBrown case -ECHILD: 1266b8faf035SNeilBrown default: 1267ab90911fSDavid Howells return false; 1268b8faf035SNeilBrown case -EISDIR: 1269b8faf035SNeilBrown return true; 1270b8faf035SNeilBrown case 0: 1271b8faf035SNeilBrown break; 1272b8faf035SNeilBrown } 127362a7375eSIan Kent 127462a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1275b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 127662a7375eSIan Kent 1277474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 12789875cf80SDavid Howells if (!mounted) 12799875cf80SDavid Howells break; 1280c7105365SAl Viro path->mnt = &mounted->mnt; 1281c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1282a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1283254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 128459430262SLinus Torvalds /* 128559430262SLinus Torvalds * Update the inode too. We don't need to re-check the 128659430262SLinus Torvalds * dentry sequence number here after this d_inode read, 128759430262SLinus Torvalds * because a mount-point is always pinned. 128859430262SLinus Torvalds */ 128959430262SLinus Torvalds *inode = path->dentry->d_inode; 12909875cf80SDavid Howells } 1291f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1292b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1293287548e4SAl Viro } 1294287548e4SAl Viro 129531e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 129631e6b01fSNick Piggin { 12974023bfc9SAl Viro struct inode *inode = nd->inode; 12987bd88377SAl Viro if (!nd->root.mnt) 129931e6b01fSNick Piggin set_root_rcu(nd); 130031e6b01fSNick Piggin 130131e6b01fSNick Piggin while (1) { 1302aed434adSAl Viro if (path_equal(&nd->path, &nd->root)) 130331e6b01fSNick Piggin break; 130431e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 130531e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 130631e6b01fSNick Piggin struct dentry *parent = old->d_parent; 130731e6b01fSNick Piggin unsigned seq; 130831e6b01fSNick Piggin 13094023bfc9SAl Viro inode = parent->d_inode; 131031e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 1311aed434adSAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 1312aed434adSAl Viro return -ECHILD; 131331e6b01fSNick Piggin nd->path.dentry = parent; 131431e6b01fSNick Piggin nd->seq = seq; 1315397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 1316397d425dSEric W. Biederman return -ENOENT; 131731e6b01fSNick Piggin break; 1318aed434adSAl Viro } else { 1319aed434adSAl Viro struct mount *mnt = real_mount(nd->path.mnt); 1320aed434adSAl Viro struct mount *mparent = mnt->mnt_parent; 1321aed434adSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1322aed434adSAl Viro struct inode *inode2 = mountpoint->d_inode; 1323aed434adSAl Viro unsigned seq = read_seqcount_begin(&mountpoint->d_seq); 1324aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1325aed434adSAl Viro return -ECHILD; 1326aed434adSAl Viro if (&mparent->mnt == nd->path.mnt) 132731e6b01fSNick Piggin break; 1328aed434adSAl Viro /* we know that mountpoint was pinned */ 1329aed434adSAl Viro nd->path.dentry = mountpoint; 1330aed434adSAl Viro nd->path.mnt = &mparent->mnt; 1331aed434adSAl Viro inode = inode2; 1332aed434adSAl Viro nd->seq = seq; 133331e6b01fSNick Piggin } 1334aed434adSAl Viro } 1335aed434adSAl Viro while (unlikely(d_mountpoint(nd->path.dentry))) { 1336b37199e6SAl Viro struct mount *mounted; 1337b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1338aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1339aed434adSAl Viro return -ECHILD; 1340b37199e6SAl Viro if (!mounted) 1341b37199e6SAl Viro break; 1342b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1343b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 13444023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1345b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1346b37199e6SAl Viro } 13474023bfc9SAl Viro nd->inode = inode; 134831e6b01fSNick Piggin return 0; 134931e6b01fSNick Piggin } 135031e6b01fSNick Piggin 13519875cf80SDavid Howells /* 1352cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1353cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1354cc53ce53SDavid Howells * caller is permitted to proceed or not. 1355cc53ce53SDavid Howells */ 13567cc90cc3SAl Viro int follow_down(struct path *path) 1357cc53ce53SDavid Howells { 1358cc53ce53SDavid Howells unsigned managed; 1359cc53ce53SDavid Howells int ret; 1360cc53ce53SDavid Howells 1361cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1362cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1363cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1364cc53ce53SDavid Howells * being held. 1365cc53ce53SDavid Howells * 1366cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1367cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1368cc53ce53SDavid Howells * other than its daemon the right to mount on its 1369cc53ce53SDavid Howells * superstructure. 1370cc53ce53SDavid Howells * 1371cc53ce53SDavid Howells * The filesystem may sleep at this point. 1372cc53ce53SDavid Howells */ 1373cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1374cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1375cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1376ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 13771aed3e42SAl Viro path->dentry, false); 1378cc53ce53SDavid Howells if (ret < 0) 1379cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1380cc53ce53SDavid Howells } 1381cc53ce53SDavid Howells 1382cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1383cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1384cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1385cc53ce53SDavid Howells if (!mounted) 1386cc53ce53SDavid Howells break; 1387cc53ce53SDavid Howells dput(path->dentry); 1388cc53ce53SDavid Howells mntput(path->mnt); 1389cc53ce53SDavid Howells path->mnt = mounted; 1390cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1391cc53ce53SDavid Howells continue; 1392cc53ce53SDavid Howells } 1393cc53ce53SDavid Howells 1394cc53ce53SDavid Howells /* Don't handle automount points here */ 1395cc53ce53SDavid Howells break; 1396cc53ce53SDavid Howells } 1397cc53ce53SDavid Howells return 0; 1398cc53ce53SDavid Howells } 13994d359507SAl Viro EXPORT_SYMBOL(follow_down); 1400cc53ce53SDavid Howells 1401cc53ce53SDavid Howells /* 14029875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 14039875cf80SDavid Howells */ 14049875cf80SDavid Howells static void follow_mount(struct path *path) 14059875cf80SDavid Howells { 14069875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 14079875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 14089875cf80SDavid Howells if (!mounted) 14099875cf80SDavid Howells break; 14109875cf80SDavid Howells dput(path->dentry); 14119875cf80SDavid Howells mntput(path->mnt); 14129875cf80SDavid Howells path->mnt = mounted; 14139875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 14149875cf80SDavid Howells } 14159875cf80SDavid Howells } 14169875cf80SDavid Howells 1417397d425dSEric W. Biederman static int follow_dotdot(struct nameidata *nd) 14181da177e4SLinus Torvalds { 14197bd88377SAl Viro if (!nd->root.mnt) 14202a737871SAl Viro set_root(nd); 1421e518ddb7SAndreas Mohr 14221da177e4SLinus Torvalds while(1) { 14234ac91378SJan Blunck struct dentry *old = nd->path.dentry; 14241da177e4SLinus Torvalds 14252a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 14262a737871SAl Viro nd->path.mnt == nd->root.mnt) { 14271da177e4SLinus Torvalds break; 14281da177e4SLinus Torvalds } 14294ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 14303088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 14313088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 14321da177e4SLinus Torvalds dput(old); 1433397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 1434397d425dSEric W. Biederman return -ENOENT; 14351da177e4SLinus Torvalds break; 14361da177e4SLinus Torvalds } 14373088dd70SAl Viro if (!follow_up(&nd->path)) 14381da177e4SLinus Torvalds break; 14391da177e4SLinus Torvalds } 144079ed0226SAl Viro follow_mount(&nd->path); 144131e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 1442397d425dSEric W. Biederman return 0; 14431da177e4SLinus Torvalds } 14441da177e4SLinus Torvalds 14451da177e4SLinus Torvalds /* 1446bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1447bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1448bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1449bad61189SMiklos Szeredi * 1450bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1451baa03890SNick Piggin */ 1452bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1453201f956eSAl Viro unsigned int flags, bool *need_lookup) 1454baa03890SNick Piggin { 1455baa03890SNick Piggin struct dentry *dentry; 1456bad61189SMiklos Szeredi int error; 1457baa03890SNick Piggin 1458bad61189SMiklos Szeredi *need_lookup = false; 1459bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1460bad61189SMiklos Szeredi if (dentry) { 146139e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1462201f956eSAl Viro error = d_revalidate(dentry, flags); 1463bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1464bad61189SMiklos Szeredi if (error < 0) { 1465bad61189SMiklos Szeredi dput(dentry); 1466bad61189SMiklos Szeredi return ERR_PTR(error); 14675542aa2fSEric W. Biederman } else { 14685542aa2fSEric W. Biederman d_invalidate(dentry); 1469bad61189SMiklos Szeredi dput(dentry); 1470bad61189SMiklos Szeredi dentry = NULL; 1471bad61189SMiklos Szeredi } 1472bad61189SMiklos Szeredi } 1473bad61189SMiklos Szeredi } 1474bad61189SMiklos Szeredi } 1475baa03890SNick Piggin 1476bad61189SMiklos Szeredi if (!dentry) { 1477bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1478baa03890SNick Piggin if (unlikely(!dentry)) 1479baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1480baa03890SNick Piggin 1481bad61189SMiklos Szeredi *need_lookup = true; 1482baa03890SNick Piggin } 1483baa03890SNick Piggin return dentry; 1484baa03890SNick Piggin } 1485baa03890SNick Piggin 1486baa03890SNick Piggin /* 148713a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 148813a2c3beSJ. Bruce Fields * unhashed. 1489bad61189SMiklos Szeredi * 1490bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 149144396f4bSJosef Bacik */ 1492bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 149372bd866aSAl Viro unsigned int flags) 149444396f4bSJosef Bacik { 149544396f4bSJosef Bacik struct dentry *old; 149644396f4bSJosef Bacik 149744396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1498bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1499e188dc02SMiklos Szeredi dput(dentry); 150044396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1501e188dc02SMiklos Szeredi } 150244396f4bSJosef Bacik 150372bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 150444396f4bSJosef Bacik if (unlikely(old)) { 150544396f4bSJosef Bacik dput(dentry); 150644396f4bSJosef Bacik dentry = old; 150744396f4bSJosef Bacik } 150844396f4bSJosef Bacik return dentry; 150944396f4bSJosef Bacik } 151044396f4bSJosef Bacik 1511a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 151272bd866aSAl Viro struct dentry *base, unsigned int flags) 1513a3255546SAl Viro { 1514bad61189SMiklos Szeredi bool need_lookup; 1515a3255546SAl Viro struct dentry *dentry; 1516a3255546SAl Viro 151772bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1518bad61189SMiklos Szeredi if (!need_lookup) 1519a3255546SAl Viro return dentry; 1520bad61189SMiklos Szeredi 152172bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1522a3255546SAl Viro } 1523a3255546SAl Viro 152444396f4bSJosef Bacik /* 15251da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 15261da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 15271da177e4SLinus Torvalds * It _is_ time-critical. 15281da177e4SLinus Torvalds */ 1529e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 1530254cf582SAl Viro struct path *path, struct inode **inode, 1531254cf582SAl Viro unsigned *seqp) 15321da177e4SLinus Torvalds { 15334ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 153431e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 15355a18fff2SAl Viro int need_reval = 1; 15365a18fff2SAl Viro int status = 1; 15379875cf80SDavid Howells int err; 15389875cf80SDavid Howells 15393cac260aSAl Viro /* 1540b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1541b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1542b04f784eSNick Piggin * do the non-racy lookup, below. 1543b04f784eSNick Piggin */ 154431e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 154531e6b01fSNick Piggin unsigned seq; 1546766c4cbfSAl Viro bool negative; 1547da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15485a18fff2SAl Viro if (!dentry) 15495a18fff2SAl Viro goto unlazy; 15505a18fff2SAl Viro 155112f8ad4bSLinus Torvalds /* 155212f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 155312f8ad4bSLinus Torvalds * the dentry name information from lookup. 155412f8ad4bSLinus Torvalds */ 155563afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1556766c4cbfSAl Viro negative = d_is_negative(dentry); 155712f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 155812f8ad4bSLinus Torvalds return -ECHILD; 155912f8ad4bSLinus Torvalds 156012f8ad4bSLinus Torvalds /* 156112f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 156212f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 156312f8ad4bSLinus Torvalds * 156412f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 156512f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 156612f8ad4bSLinus Torvalds */ 156731e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 156831e6b01fSNick Piggin return -ECHILD; 15695a18fff2SAl Viro 1570254cf582SAl Viro *seqp = seq; 157124643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 15724ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15735a18fff2SAl Viro if (unlikely(status <= 0)) { 15745a18fff2SAl Viro if (status != -ECHILD) 15755a18fff2SAl Viro need_reval = 0; 15765a18fff2SAl Viro goto unlazy; 15775a18fff2SAl Viro } 157824643087SAl Viro } 1579daf3761cSTrond Myklebust /* 1580daf3761cSTrond Myklebust * Note: do negative dentry check after revalidation in 1581daf3761cSTrond Myklebust * case that drops it. 1582daf3761cSTrond Myklebust */ 1583daf3761cSTrond Myklebust if (negative) 1584daf3761cSTrond Myklebust return -ENOENT; 158531e6b01fSNick Piggin path->mnt = mnt; 158631e6b01fSNick Piggin path->dentry = dentry; 1587254cf582SAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 15889875cf80SDavid Howells return 0; 15895a18fff2SAl Viro unlazy: 1590254cf582SAl Viro if (unlazy_walk(nd, dentry, seq)) 15915a18fff2SAl Viro return -ECHILD; 15925a18fff2SAl Viro } else { 1593e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 159424643087SAl Viro } 15955a18fff2SAl Viro 159681e6f520SAl Viro if (unlikely(!dentry)) 159781e6f520SAl Viro goto need_lookup; 15985a18fff2SAl Viro 15995a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 16004ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 16015a18fff2SAl Viro if (unlikely(status <= 0)) { 16025a18fff2SAl Viro if (status < 0) { 16035a18fff2SAl Viro dput(dentry); 16045a18fff2SAl Viro return status; 16055a18fff2SAl Viro } 16065542aa2fSEric W. Biederman d_invalidate(dentry); 16075a18fff2SAl Viro dput(dentry); 160881e6f520SAl Viro goto need_lookup; 16095a18fff2SAl Viro } 1610697f514dSMiklos Szeredi 1611766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1612766c4cbfSAl Viro dput(dentry); 1613766c4cbfSAl Viro return -ENOENT; 1614766c4cbfSAl Viro } 16151da177e4SLinus Torvalds path->mnt = mnt; 16161da177e4SLinus Torvalds path->dentry = dentry; 1617756daf26SNeilBrown err = follow_managed(path, nd); 16188402752eSAl Viro if (likely(!err)) 161963afdfc7SDavid Howells *inode = d_backing_inode(path->dentry); 16208402752eSAl Viro return err; 162181e6f520SAl Viro 162281e6f520SAl Viro need_lookup: 1623697f514dSMiklos Szeredi return 1; 1624697f514dSMiklos Szeredi } 1625697f514dSMiklos Szeredi 1626697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1627cc2a5271SAl Viro static int lookup_slow(struct nameidata *nd, struct path *path) 1628697f514dSMiklos Szeredi { 1629697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1630697f514dSMiklos Szeredi 1631697f514dSMiklos Szeredi parent = nd->path.dentry; 163281e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 163381e6f520SAl Viro 163481e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 1635cc2a5271SAl Viro dentry = __lookup_hash(&nd->last, parent, nd->flags); 163681e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 163781e6f520SAl Viro if (IS_ERR(dentry)) 163881e6f520SAl Viro return PTR_ERR(dentry); 1639697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1640697f514dSMiklos Szeredi path->dentry = dentry; 16418402752eSAl Viro return follow_managed(path, nd); 16421da177e4SLinus Torvalds } 16431da177e4SLinus Torvalds 164452094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 164552094c8aSAl Viro { 164652094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16474ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 164852094c8aSAl Viro if (err != -ECHILD) 164952094c8aSAl Viro return err; 16506e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 165152094c8aSAl Viro return -ECHILD; 165252094c8aSAl Viro } 16534ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 165452094c8aSAl Viro } 165552094c8aSAl Viro 16569856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 16579856fa1bSAl Viro { 16589856fa1bSAl Viro if (type == LAST_DOTDOT) { 16599856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 166070291aecSAl Viro return follow_dotdot_rcu(nd); 16619856fa1bSAl Viro } else 1662397d425dSEric W. Biederman return follow_dotdot(nd); 16639856fa1bSAl Viro } 16649856fa1bSAl Viro return 0; 16659856fa1bSAl Viro } 16669856fa1bSAl Viro 1667181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1668181548c0SAl Viro struct inode *inode, unsigned seq) 1669d63ff28fSAl Viro { 1670626de996SAl Viro int error; 16711cf2665bSAl Viro struct saved *last; 1672756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1673626de996SAl Viro path_to_nameidata(link, nd); 1674626de996SAl Viro return -ELOOP; 1675626de996SAl Viro } 1676bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1677cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1678cd179f44SAl Viro mntget(link->mnt); 16797973387aSAl Viro } 1680626de996SAl Viro error = nd_alloc_stack(nd); 1681626de996SAl Viro if (unlikely(error)) { 1682bc40aee0SAl Viro if (error == -ECHILD) { 1683bc40aee0SAl Viro if (unlikely(unlazy_link(nd, link, seq))) 1684bc40aee0SAl Viro return -ECHILD; 1685bc40aee0SAl Viro error = nd_alloc_stack(nd); 1686bc40aee0SAl Viro } 1687bc40aee0SAl Viro if (error) { 1688cd179f44SAl Viro path_put(link); 1689626de996SAl Viro return error; 1690626de996SAl Viro } 1691bc40aee0SAl Viro } 1692626de996SAl Viro 1693ab104923SAl Viro last = nd->stack + nd->depth++; 16941cf2665bSAl Viro last->link = *link; 1695fceef393SAl Viro clear_delayed_call(&last->done); 1696fceef393SAl Viro nd->link_inode = inode; 16970450b2d1SAl Viro last->seq = seq; 1698d63ff28fSAl Viro return 1; 1699d63ff28fSAl Viro } 1700d63ff28fSAl Viro 17013ddcd056SLinus Torvalds /* 17023ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 17033ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 17043ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 17053ddcd056SLinus Torvalds * for the common case. 17063ddcd056SLinus Torvalds */ 1707254cf582SAl Viro static inline int should_follow_link(struct nameidata *nd, struct path *link, 1708181548c0SAl Viro int follow, 1709181548c0SAl Viro struct inode *inode, unsigned seq) 17103ddcd056SLinus Torvalds { 1711d63ff28fSAl Viro if (likely(!d_is_symlink(link->dentry))) 1712d63ff28fSAl Viro return 0; 1713d63ff28fSAl Viro if (!follow) 1714d63ff28fSAl Viro return 0; 1715181548c0SAl Viro return pick_link(nd, link, inode, seq); 17163ddcd056SLinus Torvalds } 17173ddcd056SLinus Torvalds 17184693a547SAl Viro enum {WALK_GET = 1, WALK_PUT = 2}; 17194693a547SAl Viro 17204693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1721ce57dfc1SAl Viro { 1722caa85634SAl Viro struct path path; 1723ce57dfc1SAl Viro struct inode *inode; 1724254cf582SAl Viro unsigned seq; 1725ce57dfc1SAl Viro int err; 1726ce57dfc1SAl Viro /* 1727ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1728ce57dfc1SAl Viro * to be able to know about the current root directory and 1729ce57dfc1SAl Viro * parent relationships. 1730ce57dfc1SAl Viro */ 17314693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 17324693a547SAl Viro err = handle_dots(nd, nd->last_type); 17334693a547SAl Viro if (flags & WALK_PUT) 17344693a547SAl Viro put_link(nd); 17354693a547SAl Viro return err; 17364693a547SAl Viro } 1737254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1738ce57dfc1SAl Viro if (unlikely(err)) { 1739697f514dSMiklos Szeredi if (err < 0) 1740f0a9ba70SAl Viro return err; 1741697f514dSMiklos Szeredi 1742caa85634SAl Viro err = lookup_slow(nd, &path); 1743697f514dSMiklos Szeredi if (err < 0) 1744f0a9ba70SAl Viro return err; 1745697f514dSMiklos Szeredi 174663afdfc7SDavid Howells inode = d_backing_inode(path.dentry); 1747254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1748697f514dSMiklos Szeredi err = -ENOENT; 1749caa85634SAl Viro if (d_is_negative(path.dentry)) 1750697f514dSMiklos Szeredi goto out_path_put; 1751766c4cbfSAl Viro } 1752697f514dSMiklos Szeredi 17534693a547SAl Viro if (flags & WALK_PUT) 17544693a547SAl Viro put_link(nd); 1755181548c0SAl Viro err = should_follow_link(nd, &path, flags & WALK_GET, inode, seq); 1756d63ff28fSAl Viro if (unlikely(err)) 1757d63ff28fSAl Viro return err; 1758caa85634SAl Viro path_to_nameidata(&path, nd); 1759ce57dfc1SAl Viro nd->inode = inode; 1760254cf582SAl Viro nd->seq = seq; 1761ce57dfc1SAl Viro return 0; 1762697f514dSMiklos Szeredi 1763697f514dSMiklos Szeredi out_path_put: 1764caa85634SAl Viro path_to_nameidata(&path, nd); 1765697f514dSMiklos Szeredi return err; 1766ce57dfc1SAl Viro } 1767ce57dfc1SAl Viro 17681da177e4SLinus Torvalds /* 1769bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1770bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1771bfcfaa77SLinus Torvalds * 1772bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1773bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1774bfcfaa77SLinus Torvalds * fast. 1775bfcfaa77SLinus Torvalds * 1776bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1777bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1778bfcfaa77SLinus Torvalds * crossing operation. 1779bfcfaa77SLinus Torvalds * 1780bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1781bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1782bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1783bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1784bfcfaa77SLinus Torvalds */ 1785bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1786bfcfaa77SLinus Torvalds 1787f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1788bfcfaa77SLinus Torvalds 1789f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1790bfcfaa77SLinus Torvalds 1791bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1792bfcfaa77SLinus Torvalds { 179399d263d4SLinus Torvalds return hash_64(hash, 32); 1794bfcfaa77SLinus Torvalds } 1795bfcfaa77SLinus Torvalds 1796bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1797bfcfaa77SLinus Torvalds 1798bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1799bfcfaa77SLinus Torvalds 1800bfcfaa77SLinus Torvalds #endif 1801bfcfaa77SLinus Torvalds 1802bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1803bfcfaa77SLinus Torvalds { 1804bfcfaa77SLinus Torvalds unsigned long a, mask; 1805bfcfaa77SLinus Torvalds unsigned long hash = 0; 1806bfcfaa77SLinus Torvalds 1807bfcfaa77SLinus Torvalds for (;;) { 1808e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1809bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1810bfcfaa77SLinus Torvalds break; 1811bfcfaa77SLinus Torvalds hash += a; 1812f132c5beSAl Viro hash *= 9; 1813bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1814bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1815bfcfaa77SLinus Torvalds if (!len) 1816bfcfaa77SLinus Torvalds goto done; 1817bfcfaa77SLinus Torvalds } 1818a5c21dceSWill Deacon mask = bytemask_from_count(len); 1819bfcfaa77SLinus Torvalds hash += mask & a; 1820bfcfaa77SLinus Torvalds done: 1821bfcfaa77SLinus Torvalds return fold_hash(hash); 1822bfcfaa77SLinus Torvalds } 1823bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1824bfcfaa77SLinus Torvalds 1825bfcfaa77SLinus Torvalds /* 1826bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1827d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1828bfcfaa77SLinus Torvalds */ 1829d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1830bfcfaa77SLinus Torvalds { 183136126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 183236126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1833bfcfaa77SLinus Torvalds 1834bfcfaa77SLinus Torvalds hash = a = 0; 1835bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1836bfcfaa77SLinus Torvalds do { 1837bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1838bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1839e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 184036126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 184136126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1842bfcfaa77SLinus Torvalds 184336126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 184436126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 184536126f8fSLinus Torvalds 184636126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 184736126f8fSLinus Torvalds 184836126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 18499226b5b4SLinus Torvalds len += find_zero(mask); 1850d6bb3e90SLinus Torvalds return hashlen_create(fold_hash(hash), len); 1851bfcfaa77SLinus Torvalds } 1852bfcfaa77SLinus Torvalds 1853bfcfaa77SLinus Torvalds #else 1854bfcfaa77SLinus Torvalds 18550145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 18560145acc2SLinus Torvalds { 18570145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 18580145acc2SLinus Torvalds while (len--) 18590145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 18600145acc2SLinus Torvalds return end_name_hash(hash); 18610145acc2SLinus Torvalds } 1862ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 18630145acc2SLinus Torvalds 18643ddcd056SLinus Torvalds /* 1865200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1866200e9ef7SLinus Torvalds * one character. 1867200e9ef7SLinus Torvalds */ 1868d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1869200e9ef7SLinus Torvalds { 1870200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1871200e9ef7SLinus Torvalds unsigned long len = 0, c; 1872200e9ef7SLinus Torvalds 1873200e9ef7SLinus Torvalds c = (unsigned char)*name; 1874200e9ef7SLinus Torvalds do { 1875200e9ef7SLinus Torvalds len++; 1876200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1877200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1878200e9ef7SLinus Torvalds } while (c && c != '/'); 1879d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 1880200e9ef7SLinus Torvalds } 1881200e9ef7SLinus Torvalds 1882bfcfaa77SLinus Torvalds #endif 1883bfcfaa77SLinus Torvalds 1884200e9ef7SLinus Torvalds /* 18851da177e4SLinus Torvalds * Name resolution. 1886ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1887ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 18881da177e4SLinus Torvalds * 1889ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1890ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 18911da177e4SLinus Torvalds */ 18926de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 18931da177e4SLinus Torvalds { 18941da177e4SLinus Torvalds int err; 18951da177e4SLinus Torvalds 18961da177e4SLinus Torvalds while (*name=='/') 18971da177e4SLinus Torvalds name++; 18981da177e4SLinus Torvalds if (!*name) 18999e18f10aSAl Viro return 0; 19001da177e4SLinus Torvalds 19011da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 19021da177e4SLinus Torvalds for(;;) { 1903d6bb3e90SLinus Torvalds u64 hash_len; 1904fe479a58SAl Viro int type; 19051da177e4SLinus Torvalds 190652094c8aSAl Viro err = may_lookup(nd); 19071da177e4SLinus Torvalds if (err) 19083595e234SAl Viro return err; 19091da177e4SLinus Torvalds 1910d6bb3e90SLinus Torvalds hash_len = hash_name(name); 19111da177e4SLinus Torvalds 1912fe479a58SAl Viro type = LAST_NORM; 1913d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 1914fe479a58SAl Viro case 2: 1915200e9ef7SLinus Torvalds if (name[1] == '.') { 1916fe479a58SAl Viro type = LAST_DOTDOT; 191716c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 191816c2cd71SAl Viro } 1919fe479a58SAl Viro break; 1920fe479a58SAl Viro case 1: 1921fe479a58SAl Viro type = LAST_DOT; 1922fe479a58SAl Viro } 19235a202bcdSAl Viro if (likely(type == LAST_NORM)) { 19245a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 192516c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 19265a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 1927a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 1928da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 19295a202bcdSAl Viro if (err < 0) 19303595e234SAl Viro return err; 1931d6bb3e90SLinus Torvalds hash_len = this.hash_len; 1932d6bb3e90SLinus Torvalds name = this.name; 19335a202bcdSAl Viro } 19345a202bcdSAl Viro } 1935fe479a58SAl Viro 1936d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 1937d6bb3e90SLinus Torvalds nd->last.name = name; 19385f4a6a69SAl Viro nd->last_type = type; 19395f4a6a69SAl Viro 1940d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 1941d6bb3e90SLinus Torvalds if (!*name) 1942bdf6cbf1SAl Viro goto OK; 1943200e9ef7SLinus Torvalds /* 1944200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1945200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1946200e9ef7SLinus Torvalds */ 1947200e9ef7SLinus Torvalds do { 1948d6bb3e90SLinus Torvalds name++; 1949d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 19508620c238SAl Viro if (unlikely(!*name)) { 19518620c238SAl Viro OK: 1952368ee9baSAl Viro /* pathname body, done */ 19538620c238SAl Viro if (!nd->depth) 19548620c238SAl Viro return 0; 19558620c238SAl Viro name = nd->stack[nd->depth - 1].name; 1956368ee9baSAl Viro /* trailing symlink, done */ 19578620c238SAl Viro if (!name) 19588620c238SAl Viro return 0; 19598620c238SAl Viro /* last component of nested symlink */ 19604693a547SAl Viro err = walk_component(nd, WALK_GET | WALK_PUT); 19618620c238SAl Viro } else { 19624693a547SAl Viro err = walk_component(nd, WALK_GET); 19638620c238SAl Viro } 1964ce57dfc1SAl Viro if (err < 0) 19653595e234SAl Viro return err; 1966fe479a58SAl Viro 1967ce57dfc1SAl Viro if (err) { 1968626de996SAl Viro const char *s = get_link(nd); 19695a460275SAl Viro 1970a1c83681SViresh Kumar if (IS_ERR(s)) 19713595e234SAl Viro return PTR_ERR(s); 1972172a39a0SAl Viro err = 0; 197312b09578SAl Viro if (unlikely(!s)) { 197412b09578SAl Viro /* jumped */ 1975b9ff4429SAl Viro put_link(nd); 197612b09578SAl Viro } else { 1977071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 197832cd7468SAl Viro name = s; 19799e18f10aSAl Viro continue; 198048c8b0c5SAl Viro } 198131e6b01fSNick Piggin } 198297242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 198397242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 198497242f99SAl Viro if (unlazy_walk(nd, NULL, 0)) 198597242f99SAl Viro return -ECHILD; 198697242f99SAl Viro } 19873595e234SAl Viro return -ENOTDIR; 19885f4a6a69SAl Viro } 1989ce57dfc1SAl Viro } 199097242f99SAl Viro } 19911da177e4SLinus Torvalds 1992c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 199331e6b01fSNick Piggin { 199431e6b01fSNick Piggin int retval = 0; 1995c8a53ee5SAl Viro const char *s = nd->name->name; 199631e6b01fSNick Piggin 199731e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 1998980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 199931e6b01fSNick Piggin nd->depth = 0; 20005b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2001b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2002b18825a7SDavid Howells struct inode *inode = root->d_inode; 2003fd2f7cb5SAl Viro if (*s) { 200444b1d530SMiklos Szeredi if (!d_can_lookup(root)) 2005368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 20065b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 20075b6ca027SAl Viro if (retval) 2008368ee9baSAl Viro return ERR_PTR(retval); 200973d049a4SAl Viro } 20105b6ca027SAl Viro nd->path = nd->root; 20115b6ca027SAl Viro nd->inode = inode; 20125b6ca027SAl Viro if (flags & LOOKUP_RCU) { 20138b61e74fSAl Viro rcu_read_lock(); 20145b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 20158f47a016SAl Viro nd->root_seq = nd->seq; 201648a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 20175b6ca027SAl Viro } else { 20185b6ca027SAl Viro path_get(&nd->path); 20195b6ca027SAl Viro } 2020368ee9baSAl Viro return s; 20215b6ca027SAl Viro } 20225b6ca027SAl Viro 202331e6b01fSNick Piggin nd->root.mnt = NULL; 202431e6b01fSNick Piggin 202548a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 2026fd2f7cb5SAl Viro if (*s == '/') { 2027e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 20288b61e74fSAl Viro rcu_read_lock(); 202906d7137eSAl Viro set_root_rcu(nd); 203006d7137eSAl Viro nd->seq = nd->root_seq; 2031e41f7d4eSAl Viro } else { 2032e41f7d4eSAl Viro set_root(nd); 2033e41f7d4eSAl Viro path_get(&nd->root); 2034e41f7d4eSAl Viro } 203531e6b01fSNick Piggin nd->path = nd->root; 2036c8a53ee5SAl Viro } else if (nd->dfd == AT_FDCWD) { 2037e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 203831e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2039c28cc364SNick Piggin unsigned seq; 204031e6b01fSNick Piggin 20418b61e74fSAl Viro rcu_read_lock(); 204231e6b01fSNick Piggin 2043c28cc364SNick Piggin do { 2044c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 204531e6b01fSNick Piggin nd->path = fs->pwd; 2046c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2047c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2048e41f7d4eSAl Viro } else { 2049e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2050e41f7d4eSAl Viro } 205131e6b01fSNick Piggin } else { 2052582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2053c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 205431e6b01fSNick Piggin struct dentry *dentry; 205531e6b01fSNick Piggin 20562903ff01SAl Viro if (!f.file) 2057368ee9baSAl Viro return ERR_PTR(-EBADF); 205831e6b01fSNick Piggin 20592903ff01SAl Viro dentry = f.file->f_path.dentry; 206031e6b01fSNick Piggin 2061fd2f7cb5SAl Viro if (*s) { 206244b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 20632903ff01SAl Viro fdput(f); 2064368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2065f52e0c11SAl Viro } 20662903ff01SAl Viro } 20672903ff01SAl Viro 20682903ff01SAl Viro nd->path = f.file->f_path; 2069e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 20708b61e74fSAl Viro rcu_read_lock(); 207134a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 207234a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 20735590ff0dSUlrich Drepper } else { 20742903ff01SAl Viro path_get(&nd->path); 207534a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 20761da177e4SLinus Torvalds } 207734a26b99SAl Viro fdput(f); 2078368ee9baSAl Viro return s; 2079e41f7d4eSAl Viro } 2080e41f7d4eSAl Viro 208131e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 20824023bfc9SAl Viro if (!(flags & LOOKUP_RCU)) 2083368ee9baSAl Viro return s; 20844023bfc9SAl Viro if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) 2085368ee9baSAl Viro return s; 20864023bfc9SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 20874023bfc9SAl Viro nd->root.mnt = NULL; 20884023bfc9SAl Viro rcu_read_unlock(); 2089368ee9baSAl Viro return ERR_PTR(-ECHILD); 20909b4a9b14SAl Viro } 20919b4a9b14SAl Viro 20923bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 209395fa25d9SAl Viro { 209495fa25d9SAl Viro const char *s; 2095fec2fa24SAl Viro int error = may_follow_link(nd); 2096deb106c6SAl Viro if (unlikely(error)) 20973bdba28bSAl Viro return ERR_PTR(error); 209895fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2099fab51e8aSAl Viro nd->stack[0].name = NULL; 21003b2e7f75SAl Viro s = get_link(nd); 2101deb106c6SAl Viro return s ? s : ""; 210295fa25d9SAl Viro } 210395fa25d9SAl Viro 2104caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2105bd92d7feSAl Viro { 2106bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2107bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2108bd92d7feSAl Viro 2109bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 2110deb106c6SAl Viro return walk_component(nd, 21114693a547SAl Viro nd->flags & LOOKUP_FOLLOW 21124693a547SAl Viro ? nd->depth 21134693a547SAl Viro ? WALK_PUT | WALK_GET 21144693a547SAl Viro : WALK_GET 21154693a547SAl Viro : 0); 2116bd92d7feSAl Viro } 2117bd92d7feSAl Viro 21189b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2119c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 21209b4a9b14SAl Viro { 2121c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2122bd92d7feSAl Viro int err; 212331e6b01fSNick Piggin 2124368ee9baSAl Viro if (IS_ERR(s)) 2125368ee9baSAl Viro return PTR_ERR(s); 21263bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 21273bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 21283bdba28bSAl Viro s = trailing_symlink(nd); 21293bdba28bSAl Viro if (IS_ERR(s)) { 21303bdba28bSAl Viro err = PTR_ERR(s); 21316d7b5aaeSAl Viro break; 2132bd92d7feSAl Viro } 2133bd92d7feSAl Viro } 21349f1fafeeSAl Viro if (!err) 21359f1fafeeSAl Viro err = complete_walk(nd); 2136bd92d7feSAl Viro 2137deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2138deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2139bd23a539SAl Viro err = -ENOTDIR; 2140625b6d10SAl Viro if (!err) { 2141625b6d10SAl Viro *path = nd->path; 2142625b6d10SAl Viro nd->path.mnt = NULL; 2143625b6d10SAl Viro nd->path.dentry = NULL; 2144625b6d10SAl Viro } 2145deb106c6SAl Viro terminate_walk(nd); 2146bd92d7feSAl Viro return err; 214731e6b01fSNick Piggin } 214831e6b01fSNick Piggin 2149625b6d10SAl Viro static int filename_lookup(int dfd, struct filename *name, unsigned flags, 21509ad1aaa6SAl Viro struct path *path, struct path *root) 2151873f1eedSJeff Layton { 2152894bc8c4SAl Viro int retval; 21539883d185SAl Viro struct nameidata nd; 2154abc9f5beSAl Viro if (IS_ERR(name)) 2155abc9f5beSAl Viro return PTR_ERR(name); 21569ad1aaa6SAl Viro if (unlikely(root)) { 21579ad1aaa6SAl Viro nd.root = *root; 21589ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 21599ad1aaa6SAl Viro } 21609883d185SAl Viro set_nameidata(&nd, dfd, name); 2161c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2162873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2163c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2164873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2165c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2166873f1eedSJeff Layton 2167873f1eedSJeff Layton if (likely(!retval)) 2168625b6d10SAl Viro audit_inode(name, path->dentry, flags & LOOKUP_PARENT); 21699883d185SAl Viro restore_nameidata(); 2170e4bd1c1aSAl Viro putname(name); 2171873f1eedSJeff Layton return retval; 2172873f1eedSJeff Layton } 2173873f1eedSJeff Layton 21748bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2175c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2176391172c4SAl Viro struct path *parent) 21778bcb77faSAl Viro { 2178c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2179368ee9baSAl Viro int err; 2180368ee9baSAl Viro if (IS_ERR(s)) 2181368ee9baSAl Viro return PTR_ERR(s); 2182368ee9baSAl Viro err = link_path_walk(s, nd); 21838bcb77faSAl Viro if (!err) 21848bcb77faSAl Viro err = complete_walk(nd); 2185391172c4SAl Viro if (!err) { 2186391172c4SAl Viro *parent = nd->path; 2187391172c4SAl Viro nd->path.mnt = NULL; 2188391172c4SAl Viro nd->path.dentry = NULL; 2189391172c4SAl Viro } 2190deb106c6SAl Viro terminate_walk(nd); 21918bcb77faSAl Viro return err; 21928bcb77faSAl Viro } 21938bcb77faSAl Viro 21945c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2195391172c4SAl Viro unsigned int flags, struct path *parent, 2196391172c4SAl Viro struct qstr *last, int *type) 21978bcb77faSAl Viro { 21988bcb77faSAl Viro int retval; 21999883d185SAl Viro struct nameidata nd; 22008bcb77faSAl Viro 22015c31b6ceSAl Viro if (IS_ERR(name)) 22025c31b6ceSAl Viro return name; 22039883d185SAl Viro set_nameidata(&nd, dfd, name); 2204c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 22058bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2206c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 22078bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2208c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2209391172c4SAl Viro if (likely(!retval)) { 2210391172c4SAl Viro *last = nd.last; 2211391172c4SAl Viro *type = nd.last_type; 2212391172c4SAl Viro audit_inode(name, parent->dentry, LOOKUP_PARENT); 22135c31b6ceSAl Viro } else { 22145c31b6ceSAl Viro putname(name); 22155c31b6ceSAl Viro name = ERR_PTR(retval); 2216391172c4SAl Viro } 22179883d185SAl Viro restore_nameidata(); 22185c31b6ceSAl Viro return name; 22198bcb77faSAl Viro } 22208bcb77faSAl Viro 222179714f72SAl Viro /* does lookup, returns the object with parent locked */ 222279714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 22235590ff0dSUlrich Drepper { 22245c31b6ceSAl Viro struct filename *filename; 22255c31b6ceSAl Viro struct dentry *d; 2226391172c4SAl Viro struct qstr last; 2227391172c4SAl Viro int type; 222851689104SPaul Moore 22295c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 22305c31b6ceSAl Viro &last, &type); 223151689104SPaul Moore if (IS_ERR(filename)) 223251689104SPaul Moore return ERR_CAST(filename); 22335c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2234391172c4SAl Viro path_put(path); 22355c31b6ceSAl Viro putname(filename); 22365c31b6ceSAl Viro return ERR_PTR(-EINVAL); 223779714f72SAl Viro } 2238391172c4SAl Viro mutex_lock_nested(&path->dentry->d_inode->i_mutex, I_MUTEX_PARENT); 2239391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 224079714f72SAl Viro if (IS_ERR(d)) { 2241391172c4SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 2242391172c4SAl Viro path_put(path); 224379714f72SAl Viro } 224451689104SPaul Moore putname(filename); 224579714f72SAl Viro return d; 22465590ff0dSUlrich Drepper } 22475590ff0dSUlrich Drepper 2248d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2249d1811465SAl Viro { 2250abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2251abc9f5beSAl Viro flags, path, NULL); 2252d1811465SAl Viro } 22534d359507SAl Viro EXPORT_SYMBOL(kern_path); 2254d1811465SAl Viro 225516f18200SJosef 'Jeff' Sipek /** 225616f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 225716f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 225816f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 225916f18200SJosef 'Jeff' Sipek * @name: pointer to file name 226016f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2261e0a01249SAl Viro * @path: pointer to struct path to fill 226216f18200SJosef 'Jeff' Sipek */ 226316f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 226416f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2265e0a01249SAl Viro struct path *path) 226616f18200SJosef 'Jeff' Sipek { 22679ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 22689ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2269abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2270abc9f5beSAl Viro flags , path, &root); 227116f18200SJosef 'Jeff' Sipek } 22724d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 227316f18200SJosef 'Jeff' Sipek 2274eead1911SChristoph Hellwig /** 2275a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2276eead1911SChristoph Hellwig * @name: pathname component to lookup 2277eead1911SChristoph Hellwig * @base: base directory to lookup from 2278eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2279eead1911SChristoph Hellwig * 2280a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 22819e7543e9SAl Viro * not be called by generic code. 2282eead1911SChristoph Hellwig */ 2283057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2284057f6c01SJames Morris { 2285057f6c01SJames Morris struct qstr this; 22866a96ba54SAl Viro unsigned int c; 2287cda309deSMiklos Szeredi int err; 2288057f6c01SJames Morris 22892f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 22902f9092e1SDavid Woodhouse 22916a96ba54SAl Viro this.name = name; 22926a96ba54SAl Viro this.len = len; 22930145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 22946a96ba54SAl Viro if (!len) 22956a96ba54SAl Viro return ERR_PTR(-EACCES); 22966a96ba54SAl Viro 229721d8a15aSAl Viro if (unlikely(name[0] == '.')) { 229821d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 229921d8a15aSAl Viro return ERR_PTR(-EACCES); 230021d8a15aSAl Viro } 230121d8a15aSAl Viro 23026a96ba54SAl Viro while (len--) { 23036a96ba54SAl Viro c = *(const unsigned char *)name++; 23046a96ba54SAl Viro if (c == '/' || c == '\0') 23056a96ba54SAl Viro return ERR_PTR(-EACCES); 23066a96ba54SAl Viro } 23075a202bcdSAl Viro /* 23085a202bcdSAl Viro * See if the low-level filesystem might want 23095a202bcdSAl Viro * to use its own hash.. 23105a202bcdSAl Viro */ 23115a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2312da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 23135a202bcdSAl Viro if (err < 0) 23145a202bcdSAl Viro return ERR_PTR(err); 23155a202bcdSAl Viro } 2316eead1911SChristoph Hellwig 2317cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2318cda309deSMiklos Szeredi if (err) 2319cda309deSMiklos Szeredi return ERR_PTR(err); 2320cda309deSMiklos Szeredi 232172bd866aSAl Viro return __lookup_hash(&this, base, 0); 2322057f6c01SJames Morris } 23234d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2324057f6c01SJames Morris 23251fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 23261fa1e7f6SAndy Whitcroft struct path *path, int *empty) 23271da177e4SLinus Torvalds { 2328abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2329abc9f5beSAl Viro flags, path, NULL); 23301da177e4SLinus Torvalds } 2331b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 23321fa1e7f6SAndy Whitcroft 2333873f1eedSJeff Layton /* 2334873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2335873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2336873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2337873f1eedSJeff Layton * path-walking is complete. 2338873f1eedSJeff Layton */ 2339a2ec4a2dSAl Viro static inline struct filename * 2340f5beed75SAl Viro user_path_parent(int dfd, const char __user *path, 2341f5beed75SAl Viro struct path *parent, 2342f5beed75SAl Viro struct qstr *last, 2343f5beed75SAl Viro int *type, 23449e790bd6SJeff Layton unsigned int flags) 23452ad94ae6SAl Viro { 23469e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 23475c31b6ceSAl Viro return filename_parentat(dfd, getname(path), flags & LOOKUP_REVAL, 23485c31b6ceSAl Viro parent, last, type); 23492ad94ae6SAl Viro } 23502ad94ae6SAl Viro 23518033426eSJeff Layton /** 2352197df04cSAl Viro * mountpoint_last - look up last component for umount 23538033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 23548033426eSJeff Layton * @path: pointer to container for result 23558033426eSJeff Layton * 23568033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 23578033426eSJeff Layton * need to resolve the path without doing any revalidation. 23588033426eSJeff Layton * 23598033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 23608033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 23618033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 23628033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 23638033426eSJeff Layton * bogus and it doesn't exist. 23648033426eSJeff Layton * 23658033426eSJeff Layton * Returns: 23668033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 23678033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 23688033426eSJeff Layton * put in this case. 23698033426eSJeff Layton * 23708033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 23718033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 23728033426eSJeff Layton * The nd->path reference will also be put. 23738033426eSJeff Layton * 23748033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 23758033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 23768033426eSJeff Layton * to the link, and nd->path will *not* be put. 23778033426eSJeff Layton */ 23788033426eSJeff Layton static int 2379197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 23808033426eSJeff Layton { 23818033426eSJeff Layton int error = 0; 23828033426eSJeff Layton struct dentry *dentry; 23838033426eSJeff Layton struct dentry *dir = nd->path.dentry; 23848033426eSJeff Layton 238535759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 238635759521SAl Viro if (nd->flags & LOOKUP_RCU) { 23876e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 2388deb106c6SAl Viro return -ECHILD; 23898033426eSJeff Layton } 23908033426eSJeff Layton 23918033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 23928033426eSJeff Layton 23938033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 23948033426eSJeff Layton error = handle_dots(nd, nd->last_type); 239535759521SAl Viro if (error) 2396deb106c6SAl Viro return error; 23978033426eSJeff Layton dentry = dget(nd->path.dentry); 239835759521SAl Viro goto done; 23998033426eSJeff Layton } 24008033426eSJeff Layton 24018033426eSJeff Layton mutex_lock(&dir->d_inode->i_mutex); 24028033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 24038033426eSJeff Layton if (!dentry) { 24048033426eSJeff Layton /* 24058033426eSJeff Layton * No cached dentry. Mounted dentries are pinned in the cache, 24068033426eSJeff Layton * so that means that this dentry is probably a symlink or the 24078033426eSJeff Layton * path doesn't actually point to a mounted dentry. 24088033426eSJeff Layton */ 24098033426eSJeff Layton dentry = d_alloc(dir, &nd->last); 24108033426eSJeff Layton if (!dentry) { 2411bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 2412deb106c6SAl Viro return -ENOMEM; 24138033426eSJeff Layton } 241435759521SAl Viro dentry = lookup_real(dir->d_inode, dentry, nd->flags); 2415bcceeebaSDave Jones if (IS_ERR(dentry)) { 2416bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 2417deb106c6SAl Viro return PTR_ERR(dentry); 24188033426eSJeff Layton } 2419bcceeebaSDave Jones } 24208033426eSJeff Layton mutex_unlock(&dir->d_inode->i_mutex); 24218033426eSJeff Layton 242235759521SAl Viro done: 2423698934dfSDavid Howells if (d_is_negative(dentry)) { 24248033426eSJeff Layton dput(dentry); 2425deb106c6SAl Viro return -ENOENT; 242635759521SAl Viro } 2427191d7f73SAl Viro if (nd->depth) 2428191d7f73SAl Viro put_link(nd); 24298033426eSJeff Layton path->dentry = dentry; 2430295dc39dSVasily Averin path->mnt = nd->path.mnt; 2431181548c0SAl Viro error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW, 2432181548c0SAl Viro d_backing_inode(dentry), 0); 2433deb106c6SAl Viro if (unlikely(error)) 2434d63ff28fSAl Viro return error; 2435295dc39dSVasily Averin mntget(path->mnt); 24368033426eSJeff Layton follow_mount(path); 2437deb106c6SAl Viro return 0; 24388033426eSJeff Layton } 24398033426eSJeff Layton 24408033426eSJeff Layton /** 2441197df04cSAl Viro * path_mountpoint - look up a path to be umounted 24422a78b857SMasanari Iida * @nd: lookup context 24438033426eSJeff Layton * @flags: lookup flags 2444c8a53ee5SAl Viro * @path: pointer to container for result 24458033426eSJeff Layton * 24468033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2447606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 24488033426eSJeff Layton */ 24498033426eSJeff Layton static int 2450c8a53ee5SAl Viro path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) 24518033426eSJeff Layton { 2452c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2453368ee9baSAl Viro int err; 2454368ee9baSAl Viro if (IS_ERR(s)) 2455368ee9baSAl Viro return PTR_ERR(s); 24563bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 24573bdba28bSAl Viro (err = mountpoint_last(nd, path)) > 0) { 24583bdba28bSAl Viro s = trailing_symlink(nd); 24593bdba28bSAl Viro if (IS_ERR(s)) { 24603bdba28bSAl Viro err = PTR_ERR(s); 24618033426eSJeff Layton break; 24628033426eSJeff Layton } 24633bdba28bSAl Viro } 2464deb106c6SAl Viro terminate_walk(nd); 24658033426eSJeff Layton return err; 24668033426eSJeff Layton } 24678033426eSJeff Layton 24682d864651SAl Viro static int 2469668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 24702d864651SAl Viro unsigned int flags) 24712d864651SAl Viro { 24729883d185SAl Viro struct nameidata nd; 2473cbaab2dbSAl Viro int error; 2474668696dcSAl Viro if (IS_ERR(name)) 2475668696dcSAl Viro return PTR_ERR(name); 24769883d185SAl Viro set_nameidata(&nd, dfd, name); 2477c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); 24782d864651SAl Viro if (unlikely(error == -ECHILD)) 2479c8a53ee5SAl Viro error = path_mountpoint(&nd, flags, path); 24802d864651SAl Viro if (unlikely(error == -ESTALE)) 2481c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); 24822d864651SAl Viro if (likely(!error)) 2483668696dcSAl Viro audit_inode(name, path->dentry, 0); 24849883d185SAl Viro restore_nameidata(); 2485668696dcSAl Viro putname(name); 24862d864651SAl Viro return error; 24872d864651SAl Viro } 24882d864651SAl Viro 24898033426eSJeff Layton /** 2490197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 24918033426eSJeff Layton * @dfd: directory file descriptor 24928033426eSJeff Layton * @name: pathname from userland 24938033426eSJeff Layton * @flags: lookup flags 24948033426eSJeff Layton * @path: pointer to container to hold result 24958033426eSJeff Layton * 24968033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 24978033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 24988033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 24998033426eSJeff Layton * and avoid revalidating the last component. 25008033426eSJeff Layton * 25018033426eSJeff Layton * Returns 0 and populates "path" on success. 25028033426eSJeff Layton */ 25038033426eSJeff Layton int 2504197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 25058033426eSJeff Layton struct path *path) 25068033426eSJeff Layton { 2507cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 25088033426eSJeff Layton } 25098033426eSJeff Layton 25102d864651SAl Viro int 25112d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 25122d864651SAl Viro unsigned int flags) 25132d864651SAl Viro { 2514cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 25152d864651SAl Viro } 25162d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 25172d864651SAl Viro 2518cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 25191da177e4SLinus Torvalds { 25208e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2521da9592edSDavid Howells 25228e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 25231da177e4SLinus Torvalds return 0; 25248e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 25251da177e4SLinus Torvalds return 0; 252623adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 25271da177e4SLinus Torvalds } 2528cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 25291da177e4SLinus Torvalds 25301da177e4SLinus Torvalds /* 25311da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 25321da177e4SLinus Torvalds * whether the type of victim is right. 25331da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 25341da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 25351da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 25361da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 25371da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 25381da177e4SLinus Torvalds * a. be owner of dir, or 25391da177e4SLinus Torvalds * b. be owner of victim, or 25401da177e4SLinus Torvalds * c. have CAP_FOWNER capability 25411da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 25421da177e4SLinus Torvalds * links pointing to it. 25431da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 25441da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 25451da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 25461da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 25471da177e4SLinus Torvalds * nfs_async_unlink(). 25481da177e4SLinus Torvalds */ 2549b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 25501da177e4SLinus Torvalds { 255163afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 25521da177e4SLinus Torvalds int error; 25531da177e4SLinus Torvalds 2554b18825a7SDavid Howells if (d_is_negative(victim)) 25551da177e4SLinus Torvalds return -ENOENT; 2556b18825a7SDavid Howells BUG_ON(!inode); 25571da177e4SLinus Torvalds 25581da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 25594fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 25601da177e4SLinus Torvalds 2561f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 25621da177e4SLinus Torvalds if (error) 25631da177e4SLinus Torvalds return error; 25641da177e4SLinus Torvalds if (IS_APPEND(dir)) 25651da177e4SLinus Torvalds return -EPERM; 2566b18825a7SDavid Howells 2567b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2568b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 25691da177e4SLinus Torvalds return -EPERM; 25701da177e4SLinus Torvalds if (isdir) { 257144b1d530SMiklos Szeredi if (!d_is_dir(victim)) 25721da177e4SLinus Torvalds return -ENOTDIR; 25731da177e4SLinus Torvalds if (IS_ROOT(victim)) 25741da177e4SLinus Torvalds return -EBUSY; 257544b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 25761da177e4SLinus Torvalds return -EISDIR; 25771da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25781da177e4SLinus Torvalds return -ENOENT; 25791da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 25801da177e4SLinus Torvalds return -EBUSY; 25811da177e4SLinus Torvalds return 0; 25821da177e4SLinus Torvalds } 25831da177e4SLinus Torvalds 25841da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 25851da177e4SLinus Torvalds * dir. 25861da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 25871da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 25881da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 25891da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 25901da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 25911da177e4SLinus Torvalds */ 2592a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 25931da177e4SLinus Torvalds { 259414e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 25951da177e4SLinus Torvalds if (child->d_inode) 25961da177e4SLinus Torvalds return -EEXIST; 25971da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25981da177e4SLinus Torvalds return -ENOENT; 2599f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 26001da177e4SLinus Torvalds } 26011da177e4SLinus Torvalds 26021da177e4SLinus Torvalds /* 26031da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 26041da177e4SLinus Torvalds */ 26051da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 26061da177e4SLinus Torvalds { 26071da177e4SLinus Torvalds struct dentry *p; 26081da177e4SLinus Torvalds 26091da177e4SLinus Torvalds if (p1 == p2) { 2610f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 26111da177e4SLinus Torvalds return NULL; 26121da177e4SLinus Torvalds } 26131da177e4SLinus Torvalds 2614a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 26151da177e4SLinus Torvalds 2616e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2617e2761a11SOGAWA Hirofumi if (p) { 2618f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2619f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 26201da177e4SLinus Torvalds return p; 26211da177e4SLinus Torvalds } 26221da177e4SLinus Torvalds 2623e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2624e2761a11SOGAWA Hirofumi if (p) { 2625f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2626f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 26271da177e4SLinus Torvalds return p; 26281da177e4SLinus Torvalds } 26291da177e4SLinus Torvalds 2630f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2631d1b72cc6SMiklos Szeredi mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); 26321da177e4SLinus Torvalds return NULL; 26331da177e4SLinus Torvalds } 26344d359507SAl Viro EXPORT_SYMBOL(lock_rename); 26351da177e4SLinus Torvalds 26361da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 26371da177e4SLinus Torvalds { 26381b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 26391da177e4SLinus Torvalds if (p1 != p2) { 26401b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2641a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 26421da177e4SLinus Torvalds } 26431da177e4SLinus Torvalds } 26444d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 26451da177e4SLinus Torvalds 26464acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2647312b63fbSAl Viro bool want_excl) 26481da177e4SLinus Torvalds { 2649a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 26501da177e4SLinus Torvalds if (error) 26511da177e4SLinus Torvalds return error; 26521da177e4SLinus Torvalds 2653acfa4380SAl Viro if (!dir->i_op->create) 26541da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 26551da177e4SLinus Torvalds mode &= S_IALLUGO; 26561da177e4SLinus Torvalds mode |= S_IFREG; 26571da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 26581da177e4SLinus Torvalds if (error) 26591da177e4SLinus Torvalds return error; 2660312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2661a74574aaSStephen Smalley if (!error) 2662f38aa942SAmy Griffis fsnotify_create(dir, dentry); 26631da177e4SLinus Torvalds return error; 26641da177e4SLinus Torvalds } 26654d359507SAl Viro EXPORT_SYMBOL(vfs_create); 26661da177e4SLinus Torvalds 266773d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 26681da177e4SLinus Torvalds { 26693fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 26701da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 26711da177e4SLinus Torvalds int error; 26721da177e4SLinus Torvalds 2673bcda7652SAl Viro /* O_PATH? */ 2674bcda7652SAl Viro if (!acc_mode) 2675bcda7652SAl Viro return 0; 2676bcda7652SAl Viro 26771da177e4SLinus Torvalds if (!inode) 26781da177e4SLinus Torvalds return -ENOENT; 26791da177e4SLinus Torvalds 2680c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2681c8fe8f30SChristoph Hellwig case S_IFLNK: 26821da177e4SLinus Torvalds return -ELOOP; 2683c8fe8f30SChristoph Hellwig case S_IFDIR: 2684c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 26851da177e4SLinus Torvalds return -EISDIR; 2686c8fe8f30SChristoph Hellwig break; 2687c8fe8f30SChristoph Hellwig case S_IFBLK: 2688c8fe8f30SChristoph Hellwig case S_IFCHR: 26893fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 26901da177e4SLinus Torvalds return -EACCES; 2691c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2692c8fe8f30SChristoph Hellwig case S_IFIFO: 2693c8fe8f30SChristoph Hellwig case S_IFSOCK: 26941da177e4SLinus Torvalds flag &= ~O_TRUNC; 2695c8fe8f30SChristoph Hellwig break; 26964a3fd211SDave Hansen } 2697b41572e9SDave Hansen 26983fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2699b41572e9SDave Hansen if (error) 2700b41572e9SDave Hansen return error; 27016146f0d5SMimi Zohar 27021da177e4SLinus Torvalds /* 27031da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 27041da177e4SLinus Torvalds */ 27051da177e4SLinus Torvalds if (IS_APPEND(inode)) { 27068737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 27077715b521SAl Viro return -EPERM; 27081da177e4SLinus Torvalds if (flag & O_TRUNC) 27097715b521SAl Viro return -EPERM; 27101da177e4SLinus Torvalds } 27111da177e4SLinus Torvalds 27121da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 27132e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 27147715b521SAl Viro return -EPERM; 27151da177e4SLinus Torvalds 2716f3c7691eSJ. Bruce Fields return 0; 27177715b521SAl Viro } 27187715b521SAl Viro 2719e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 27207715b521SAl Viro { 2721e1181ee6SJeff Layton struct path *path = &filp->f_path; 27227715b521SAl Viro struct inode *inode = path->dentry->d_inode; 27237715b521SAl Viro int error = get_write_access(inode); 27241da177e4SLinus Torvalds if (error) 27257715b521SAl Viro return error; 27261da177e4SLinus Torvalds /* 27271da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 27281da177e4SLinus Torvalds */ 2729d7a06983SJeff Layton error = locks_verify_locked(filp); 2730be6d3e56SKentaro Takeda if (!error) 2731ea0d3ab2STetsuo Handa error = security_path_truncate(path); 27321da177e4SLinus Torvalds if (!error) { 27337715b521SAl Viro error = do_truncate(path->dentry, 0, 2734d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2735e1181ee6SJeff Layton filp); 27361da177e4SLinus Torvalds } 27371da177e4SLinus Torvalds put_write_access(inode); 2738acd0c935SMimi Zohar return error; 27391da177e4SLinus Torvalds } 27401da177e4SLinus Torvalds 2741d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2742d57999e1SDave Hansen { 27438a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 27448a5e929dSAl Viro flag--; 2745d57999e1SDave Hansen return flag; 2746d57999e1SDave Hansen } 2747d57999e1SDave Hansen 2748d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2749d18e9008SMiklos Szeredi { 2750d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2751d18e9008SMiklos Szeredi if (error) 2752d18e9008SMiklos Szeredi return error; 2753d18e9008SMiklos Szeredi 2754d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2755d18e9008SMiklos Szeredi if (error) 2756d18e9008SMiklos Szeredi return error; 2757d18e9008SMiklos Szeredi 2758d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2759d18e9008SMiklos Szeredi } 2760d18e9008SMiklos Szeredi 27611acf0af9SDavid Howells /* 27621acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 27631acf0af9SDavid Howells * dentry. 27641acf0af9SDavid Howells * 27651acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 27661acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 27671acf0af9SDavid Howells * 27681acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 27691acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 27701acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 27711acf0af9SDavid Howells * 27721acf0af9SDavid Howells * Returns an error code otherwise. 27731acf0af9SDavid Howells */ 27742675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 277530d90494SAl Viro struct path *path, struct file *file, 2776015c3bbcSMiklos Szeredi const struct open_flags *op, 277764894cf8SAl Viro bool got_write, bool need_lookup, 277847237687SAl Viro int *opened) 2779d18e9008SMiklos Szeredi { 2780d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2781d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2782d18e9008SMiklos Szeredi umode_t mode; 2783d18e9008SMiklos Szeredi int error; 2784d18e9008SMiklos Szeredi int acc_mode; 2785d18e9008SMiklos Szeredi int create_error = 0; 2786d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2787116cc022SMiklos Szeredi bool excl; 2788d18e9008SMiklos Szeredi 2789d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2790d18e9008SMiklos Szeredi 2791d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2792d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 27932675a4ebSAl Viro error = -ENOENT; 2794d18e9008SMiklos Szeredi goto out; 2795d18e9008SMiklos Szeredi } 2796d18e9008SMiklos Szeredi 279762b259d8SMiklos Szeredi mode = op->mode; 2798d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2799d18e9008SMiklos Szeredi mode &= ~current_umask(); 2800d18e9008SMiklos Szeredi 2801116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2802116cc022SMiklos Szeredi if (excl) 2803d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2804d18e9008SMiklos Szeredi 2805d18e9008SMiklos Szeredi /* 2806d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2807d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2808d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2809d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2810d18e9008SMiklos Szeredi * 2811d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2812d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2813d18e9008SMiklos Szeredi */ 281464894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 281564894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 281664894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2817d18e9008SMiklos Szeredi /* 2818d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2819d18e9008SMiklos Szeredi * back to lookup + open 2820d18e9008SMiklos Szeredi */ 2821d18e9008SMiklos Szeredi goto no_open; 2822d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2823d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 282464894cf8SAl Viro create_error = -EROFS; 2825d18e9008SMiklos Szeredi goto no_open; 2826d18e9008SMiklos Szeredi } else { 2827d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 282864894cf8SAl Viro create_error = -EROFS; 2829d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2830d18e9008SMiklos Szeredi } 2831d18e9008SMiklos Szeredi } 2832d18e9008SMiklos Szeredi 2833d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 283438227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2835d18e9008SMiklos Szeredi if (error) { 2836d18e9008SMiklos Szeredi create_error = error; 2837d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2838d18e9008SMiklos Szeredi goto no_open; 2839d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2840d18e9008SMiklos Szeredi } 2841d18e9008SMiklos Szeredi } 2842d18e9008SMiklos Szeredi 2843d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2844d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2845d18e9008SMiklos Szeredi 284630d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 284730d90494SAl Viro file->f_path.mnt = nd->path.mnt; 284830d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 284947237687SAl Viro opened); 2850d9585277SAl Viro if (error < 0) { 2851d9585277SAl Viro if (create_error && error == -ENOENT) 2852d9585277SAl Viro error = create_error; 2853d18e9008SMiklos Szeredi goto out; 2854d18e9008SMiklos Szeredi } 2855d18e9008SMiklos Szeredi 2856d9585277SAl Viro if (error) { /* returned 1, that is */ 285730d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 28582675a4ebSAl Viro error = -EIO; 2859d18e9008SMiklos Szeredi goto out; 2860d18e9008SMiklos Szeredi } 286130d90494SAl Viro if (file->f_path.dentry) { 2862d18e9008SMiklos Szeredi dput(dentry); 286330d90494SAl Viro dentry = file->f_path.dentry; 2864d18e9008SMiklos Szeredi } 286503da633aSAl Viro if (*opened & FILE_CREATED) 286603da633aSAl Viro fsnotify_create(dir, dentry); 286703da633aSAl Viro if (!dentry->d_inode) { 286803da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 286903da633aSAl Viro if (create_error) { 287062b2ce96SSage Weil error = create_error; 287162b2ce96SSage Weil goto out; 287262b2ce96SSage Weil } 287303da633aSAl Viro } else { 287403da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 287503da633aSAl Viro error = -EEXIST; 287603da633aSAl Viro goto out; 287703da633aSAl Viro } 287803da633aSAl Viro } 2879d18e9008SMiklos Szeredi goto looked_up; 2880d18e9008SMiklos Szeredi } 2881d18e9008SMiklos Szeredi 2882d18e9008SMiklos Szeredi /* 2883d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2884d18e9008SMiklos Szeredi * here. 2885d18e9008SMiklos Szeredi */ 288603da633aSAl Viro acc_mode = op->acc_mode; 288703da633aSAl Viro if (*opened & FILE_CREATED) { 288803da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 288903da633aSAl Viro fsnotify_create(dir, dentry); 289003da633aSAl Viro acc_mode = MAY_OPEN; 289103da633aSAl Viro } 28922675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 28932675a4ebSAl Viro if (error) 28942675a4ebSAl Viro fput(file); 2895d18e9008SMiklos Szeredi 2896d18e9008SMiklos Szeredi out: 2897d18e9008SMiklos Szeredi dput(dentry); 28982675a4ebSAl Viro return error; 2899d18e9008SMiklos Szeredi 2900d18e9008SMiklos Szeredi no_open: 2901d18e9008SMiklos Szeredi if (need_lookup) { 290272bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2903d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 29042675a4ebSAl Viro return PTR_ERR(dentry); 2905d18e9008SMiklos Szeredi 2906d18e9008SMiklos Szeredi if (create_error) { 2907d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2908d18e9008SMiklos Szeredi 29092675a4ebSAl Viro error = create_error; 2910d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2911d18e9008SMiklos Szeredi if (!dentry->d_inode) 2912d18e9008SMiklos Szeredi goto out; 2913d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2914d18e9008SMiklos Szeredi goto out; 2915d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2916e36cb0b8SDavid Howells d_is_reg(dentry)) { 2917d18e9008SMiklos Szeredi goto out; 2918d18e9008SMiklos Szeredi } 2919d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2920d18e9008SMiklos Szeredi } 2921d18e9008SMiklos Szeredi } 2922d18e9008SMiklos Szeredi looked_up: 2923d18e9008SMiklos Szeredi path->dentry = dentry; 2924d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 29252675a4ebSAl Viro return 1; 2926d18e9008SMiklos Szeredi } 2927d18e9008SMiklos Szeredi 292831e6b01fSNick Piggin /* 29291acf0af9SDavid Howells * Look up and maybe create and open the last component. 2930d58ffd35SMiklos Szeredi * 2931d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2932d58ffd35SMiklos Szeredi * 29331acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 29341acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 29351acf0af9SDavid Howells * 29361acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 29371acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 29381acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 29391acf0af9SDavid Howells * specified then a negative dentry may be returned. 29401acf0af9SDavid Howells * 29411acf0af9SDavid Howells * An error code is returned otherwise. 29421acf0af9SDavid Howells * 29431acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 29441acf0af9SDavid Howells * cleared otherwise prior to returning. 2945d58ffd35SMiklos Szeredi */ 29462675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 294730d90494SAl Viro struct file *file, 2948d58ffd35SMiklos Szeredi const struct open_flags *op, 294964894cf8SAl Viro bool got_write, int *opened) 2950d58ffd35SMiklos Szeredi { 2951d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 295254ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2953d58ffd35SMiklos Szeredi struct dentry *dentry; 2954d58ffd35SMiklos Szeredi int error; 295554ef4872SMiklos Szeredi bool need_lookup; 2956d58ffd35SMiklos Szeredi 295747237687SAl Viro *opened &= ~FILE_CREATED; 2958201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2959d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 29602675a4ebSAl Viro return PTR_ERR(dentry); 2961d58ffd35SMiklos Szeredi 2962d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2963d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2964d18e9008SMiklos Szeredi goto out_no_open; 2965d18e9008SMiklos Szeredi 2966d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 296764894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 296847237687SAl Viro need_lookup, opened); 2969d18e9008SMiklos Szeredi } 2970d18e9008SMiklos Szeredi 297154ef4872SMiklos Szeredi if (need_lookup) { 297254ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 297354ef4872SMiklos Szeredi 297472bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 297554ef4872SMiklos Szeredi if (IS_ERR(dentry)) 29762675a4ebSAl Viro return PTR_ERR(dentry); 297754ef4872SMiklos Szeredi } 297854ef4872SMiklos Szeredi 2979d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2980d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2981d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2982d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2983d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2984d58ffd35SMiklos Szeredi /* 2985d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2986d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2987d58ffd35SMiklos Szeredi * the time when the file is created and when 2988d58ffd35SMiklos Szeredi * a permanent write count is taken through 2989015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 2990d58ffd35SMiklos Szeredi */ 299164894cf8SAl Viro if (!got_write) { 299264894cf8SAl Viro error = -EROFS; 2993d58ffd35SMiklos Szeredi goto out_dput; 299464894cf8SAl Viro } 299547237687SAl Viro *opened |= FILE_CREATED; 2996d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2997d58ffd35SMiklos Szeredi if (error) 2998d58ffd35SMiklos Szeredi goto out_dput; 2999312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 3000312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 3001d58ffd35SMiklos Szeredi if (error) 3002d58ffd35SMiklos Szeredi goto out_dput; 3003d58ffd35SMiklos Szeredi } 3004d18e9008SMiklos Szeredi out_no_open: 3005d58ffd35SMiklos Szeredi path->dentry = dentry; 3006d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 30072675a4ebSAl Viro return 1; 3008d58ffd35SMiklos Szeredi 3009d58ffd35SMiklos Szeredi out_dput: 3010d58ffd35SMiklos Szeredi dput(dentry); 30112675a4ebSAl Viro return error; 3012d58ffd35SMiklos Szeredi } 3013d58ffd35SMiklos Szeredi 3014d58ffd35SMiklos Szeredi /* 3015fe2d35ffSAl Viro * Handle the last step of open() 301631e6b01fSNick Piggin */ 3017896475d5SAl Viro static int do_last(struct nameidata *nd, 301830d90494SAl Viro struct file *file, const struct open_flags *op, 301976ae2a5aSAl Viro int *opened) 3020fb1cc555SAl Viro { 3021a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3022ca344a89SAl Viro int open_flag = op->open_flag; 302377d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 302464894cf8SAl Viro bool got_write = false; 3025bcda7652SAl Viro int acc_mode = op->acc_mode; 3026254cf582SAl Viro unsigned seq; 3027a1eb3315SMiklos Szeredi struct inode *inode; 302816b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 3029896475d5SAl Viro struct path path; 303016b1c1cdSMiklos Szeredi bool retried = false; 303116c2cd71SAl Viro int error; 3032fb1cc555SAl Viro 3033c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3034c3e380b0SAl Viro nd->flags |= op->intent; 3035c3e380b0SAl Viro 3036bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3037fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3038deb106c6SAl Viro if (unlikely(error)) 30392675a4ebSAl Viro return error; 3040e83db167SMiklos Szeredi goto finish_open; 30411f36f774SAl Viro } 3042a2c36b45SAl Viro 3043ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3044fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3045fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3046fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3047254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 304871574865SMiklos Szeredi if (likely(!error)) 304971574865SMiklos Szeredi goto finish_lookup; 305071574865SMiklos Szeredi 3051ce57dfc1SAl Viro if (error < 0) 3052deb106c6SAl Viro return error; 3053a1eb3315SMiklos Szeredi 305437d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 3055b6183df7SMiklos Szeredi } else { 3056fe2d35ffSAl Viro /* create side of things */ 3057a3fbbde7SAl Viro /* 3058b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3059b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3060b6183df7SMiklos Szeredi * about to look up 3061a3fbbde7SAl Viro */ 30629f1fafeeSAl Viro error = complete_walk(nd); 3063e8bb73dfSAl Viro if (error) 30642675a4ebSAl Viro return error; 3065fe2d35ffSAl Viro 306676ae2a5aSAl Viro audit_inode(nd->name, dir, LOOKUP_PARENT); 30671f36f774SAl Viro /* trailing slashes? */ 3068deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3069deb106c6SAl Viro return -EISDIR; 3070b6183df7SMiklos Szeredi } 30711f36f774SAl Viro 307216b1c1cdSMiklos Szeredi retry_lookup: 307364894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 307464894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 307564894cf8SAl Viro if (!error) 307664894cf8SAl Viro got_write = true; 307764894cf8SAl Viro /* 307864894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 307964894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 308064894cf8SAl Viro * dropping this one anyway. 308164894cf8SAl Viro */ 308264894cf8SAl Viro } 3083a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 3084896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 3085fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 3086fb1cc555SAl Viro 30872675a4ebSAl Viro if (error <= 0) { 30882675a4ebSAl Viro if (error) 3089d58ffd35SMiklos Szeredi goto out; 30906c0d46c4SAl Viro 309147237687SAl Viro if ((*opened & FILE_CREATED) || 3092496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 309377d660a8SMiklos Szeredi will_truncate = false; 3094d18e9008SMiklos Szeredi 309576ae2a5aSAl Viro audit_inode(nd->name, file->f_path.dentry, 0); 3096d18e9008SMiklos Szeredi goto opened; 3097d18e9008SMiklos Szeredi } 3098d18e9008SMiklos Szeredi 309947237687SAl Viro if (*opened & FILE_CREATED) { 31009b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3101ca344a89SAl Viro open_flag &= ~O_TRUNC; 310277d660a8SMiklos Szeredi will_truncate = false; 3103bcda7652SAl Viro acc_mode = MAY_OPEN; 3104896475d5SAl Viro path_to_nameidata(&path, nd); 3105e83db167SMiklos Szeredi goto finish_open_created; 3106fb1cc555SAl Viro } 3107fb1cc555SAl Viro 3108fb1cc555SAl Viro /* 31093134f37eSJeff Layton * create/update audit record if it already exists. 3110fb1cc555SAl Viro */ 3111896475d5SAl Viro if (d_is_positive(path.dentry)) 311276ae2a5aSAl Viro audit_inode(nd->name, path.dentry, 0); 3113fb1cc555SAl Viro 3114d18e9008SMiklos Szeredi /* 3115d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3116d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3117d18e9008SMiklos Szeredi * necessary...) 3118d18e9008SMiklos Szeredi */ 311964894cf8SAl Viro if (got_write) { 3120d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 312164894cf8SAl Viro got_write = false; 3122d18e9008SMiklos Szeredi } 3123d18e9008SMiklos Szeredi 3124deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3125deb106c6SAl Viro path_to_nameidata(&path, nd); 3126deb106c6SAl Viro return -EEXIST; 3127deb106c6SAl Viro } 3128fb1cc555SAl Viro 3129756daf26SNeilBrown error = follow_managed(&path, nd); 3130deb106c6SAl Viro if (unlikely(error < 0)) 3131deb106c6SAl Viro return error; 3132a3fbbde7SAl Viro 3133decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 313463afdfc7SDavid Howells inode = d_backing_inode(path.dentry); 3135254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3136deb106c6SAl Viro if (unlikely(d_is_negative(path.dentry))) { 3137896475d5SAl Viro path_to_nameidata(&path, nd); 3138deb106c6SAl Viro return -ENOENT; 313954c33e7fSMiklos Szeredi } 3140766c4cbfSAl Viro finish_lookup: 3141191d7f73SAl Viro if (nd->depth) 3142191d7f73SAl Viro put_link(nd); 3143181548c0SAl Viro error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW, 3144181548c0SAl Viro inode, seq); 3145deb106c6SAl Viro if (unlikely(error)) 3146d63ff28fSAl Viro return error; 3147fb1cc555SAl Viro 3148896475d5SAl Viro if (unlikely(d_is_symlink(path.dentry)) && !(open_flag & O_PATH)) { 3149896475d5SAl Viro path_to_nameidata(&path, nd); 3150deb106c6SAl Viro return -ELOOP; 3151a5cfe2d5SAl Viro } 3152a5cfe2d5SAl Viro 3153896475d5SAl Viro if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { 3154896475d5SAl Viro path_to_nameidata(&path, nd); 315516b1c1cdSMiklos Szeredi } else { 315616b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 3157896475d5SAl Viro save_parent.mnt = mntget(path.mnt); 3158896475d5SAl Viro nd->path.dentry = path.dentry; 315916b1c1cdSMiklos Szeredi 316016b1c1cdSMiklos Szeredi } 3161decf3400SMiklos Szeredi nd->inode = inode; 3162254cf582SAl Viro nd->seq = seq; 3163a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3164bc77daa7SAl Viro finish_open: 3165a3fbbde7SAl Viro error = complete_walk(nd); 316616b1c1cdSMiklos Szeredi if (error) { 316716b1c1cdSMiklos Szeredi path_put(&save_parent); 31682675a4ebSAl Viro return error; 316916b1c1cdSMiklos Szeredi } 317076ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 3171fb1cc555SAl Viro error = -EISDIR; 317244b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 31732675a4ebSAl Viro goto out; 3174af2f5542SMiklos Szeredi error = -ENOTDIR; 317544b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 31762675a4ebSAl Viro goto out; 31774bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 317877d660a8SMiklos Szeredi will_truncate = false; 31796c0d46c4SAl Viro 31800f9d1a10SAl Viro if (will_truncate) { 31810f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 31820f9d1a10SAl Viro if (error) 31832675a4ebSAl Viro goto out; 318464894cf8SAl Viro got_write = true; 31850f9d1a10SAl Viro } 3186e83db167SMiklos Szeredi finish_open_created: 3187bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3188ca344a89SAl Viro if (error) 31892675a4ebSAl Viro goto out; 31904aa7c634SMiklos Szeredi 31914aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 31924aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 31934aa7c634SMiklos Szeredi if (!error) { 31944aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 31954aa7c634SMiklos Szeredi } else { 319630d90494SAl Viro if (error == -EOPENSTALE) 3197f60dc3dbSMiklos Szeredi goto stale_open; 3198015c3bbcSMiklos Szeredi goto out; 3199f60dc3dbSMiklos Szeredi } 3200a8277b9bSMiklos Szeredi opened: 32012675a4ebSAl Viro error = open_check_o_direct(file); 3202015c3bbcSMiklos Szeredi if (error) 3203015c3bbcSMiklos Szeredi goto exit_fput; 32043034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3205aa4caadbSMiklos Szeredi if (error) 3206aa4caadbSMiklos Szeredi goto exit_fput; 3207aa4caadbSMiklos Szeredi 32080f9d1a10SAl Viro if (will_truncate) { 32092675a4ebSAl Viro error = handle_truncate(file); 3210aa4caadbSMiklos Szeredi if (error) 3211aa4caadbSMiklos Szeredi goto exit_fput; 32120f9d1a10SAl Viro } 3213ca344a89SAl Viro out: 321464894cf8SAl Viro if (got_write) 32150f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 321616b1c1cdSMiklos Szeredi path_put(&save_parent); 32172675a4ebSAl Viro return error; 3218fb1cc555SAl Viro 3219015c3bbcSMiklos Szeredi exit_fput: 32202675a4ebSAl Viro fput(file); 32212675a4ebSAl Viro goto out; 3222015c3bbcSMiklos Szeredi 3223f60dc3dbSMiklos Szeredi stale_open: 3224f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3225f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3226f60dc3dbSMiklos Szeredi goto out; 3227f60dc3dbSMiklos Szeredi 3228f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3229f60dc3dbSMiklos Szeredi path_put(&nd->path); 3230f60dc3dbSMiklos Szeredi nd->path = save_parent; 3231f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3232f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3233f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 323464894cf8SAl Viro if (got_write) { 3235f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 323664894cf8SAl Viro got_write = false; 3237f60dc3dbSMiklos Szeredi } 3238f60dc3dbSMiklos Szeredi retried = true; 3239f60dc3dbSMiklos Szeredi goto retry_lookup; 3240fb1cc555SAl Viro } 3241fb1cc555SAl Viro 3242c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 324360545d0dSAl Viro const struct open_flags *op, 324460545d0dSAl Viro struct file *file, int *opened) 324560545d0dSAl Viro { 324660545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 3247625b6d10SAl Viro struct dentry *child; 324860545d0dSAl Viro struct inode *dir; 3249625b6d10SAl Viro struct path path; 3250c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 325160545d0dSAl Viro if (unlikely(error)) 325260545d0dSAl Viro return error; 3253625b6d10SAl Viro error = mnt_want_write(path.mnt); 325460545d0dSAl Viro if (unlikely(error)) 325560545d0dSAl Viro goto out; 3256625b6d10SAl Viro dir = path.dentry->d_inode; 325760545d0dSAl Viro /* we want directory to be writable */ 3258625b6d10SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 325960545d0dSAl Viro if (error) 326060545d0dSAl Viro goto out2; 326160545d0dSAl Viro if (!dir->i_op->tmpfile) { 326260545d0dSAl Viro error = -EOPNOTSUPP; 326360545d0dSAl Viro goto out2; 326460545d0dSAl Viro } 3265625b6d10SAl Viro child = d_alloc(path.dentry, &name); 326660545d0dSAl Viro if (unlikely(!child)) { 326760545d0dSAl Viro error = -ENOMEM; 326860545d0dSAl Viro goto out2; 326960545d0dSAl Viro } 3270625b6d10SAl Viro dput(path.dentry); 3271625b6d10SAl Viro path.dentry = child; 3272625b6d10SAl Viro error = dir->i_op->tmpfile(dir, child, op->mode); 327360545d0dSAl Viro if (error) 327460545d0dSAl Viro goto out2; 3275c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 327669a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 3277625b6d10SAl Viro error = may_open(&path, MAY_OPEN, op->open_flag); 327860545d0dSAl Viro if (error) 327960545d0dSAl Viro goto out2; 3280625b6d10SAl Viro file->f_path.mnt = path.mnt; 3281625b6d10SAl Viro error = finish_open(file, child, NULL, opened); 328260545d0dSAl Viro if (error) 328360545d0dSAl Viro goto out2; 328460545d0dSAl Viro error = open_check_o_direct(file); 3285f4e0c30cSAl Viro if (error) { 328660545d0dSAl Viro fput(file); 3287f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3288f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3289f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3290f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3291f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3292f4e0c30cSAl Viro } 329360545d0dSAl Viro out2: 3294625b6d10SAl Viro mnt_drop_write(path.mnt); 329560545d0dSAl Viro out: 3296625b6d10SAl Viro path_put(&path); 329760545d0dSAl Viro return error; 329860545d0dSAl Viro } 329960545d0dSAl Viro 3300c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3301c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 33021da177e4SLinus Torvalds { 3303368ee9baSAl Viro const char *s; 330430d90494SAl Viro struct file *file; 330547237687SAl Viro int opened = 0; 330613aab428SAl Viro int error; 330731e6b01fSNick Piggin 330830d90494SAl Viro file = get_empty_filp(); 33091afc99beSAl Viro if (IS_ERR(file)) 33101afc99beSAl Viro return file; 331131e6b01fSNick Piggin 331230d90494SAl Viro file->f_flags = op->open_flag; 331331e6b01fSNick Piggin 3314bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 3315c8a53ee5SAl Viro error = do_tmpfile(nd, flags, op, file, &opened); 3316f15133dfSAl Viro goto out2; 331760545d0dSAl Viro } 331860545d0dSAl Viro 3319c8a53ee5SAl Viro s = path_init(nd, flags); 3320368ee9baSAl Viro if (IS_ERR(s)) { 3321368ee9baSAl Viro put_filp(file); 3322368ee9baSAl Viro return ERR_CAST(s); 3323368ee9baSAl Viro } 33243bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 332576ae2a5aSAl Viro (error = do_last(nd, file, op, &opened)) > 0) { 332673d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 33273bdba28bSAl Viro s = trailing_symlink(nd); 33283bdba28bSAl Viro if (IS_ERR(s)) { 33293bdba28bSAl Viro error = PTR_ERR(s); 33302675a4ebSAl Viro break; 3331806b681cSAl Viro } 33323bdba28bSAl Viro } 3333deb106c6SAl Viro terminate_walk(nd); 3334f15133dfSAl Viro out2: 33352675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 33362675a4ebSAl Viro BUG_ON(!error); 333730d90494SAl Viro put_filp(file); 3338015c3bbcSMiklos Szeredi } 33392675a4ebSAl Viro if (unlikely(error)) { 33402675a4ebSAl Viro if (error == -EOPENSTALE) { 33412675a4ebSAl Viro if (flags & LOOKUP_RCU) 33422675a4ebSAl Viro error = -ECHILD; 33432675a4ebSAl Viro else 33442675a4ebSAl Viro error = -ESTALE; 33452675a4ebSAl Viro } 33462675a4ebSAl Viro file = ERR_PTR(error); 33472675a4ebSAl Viro } 33482675a4ebSAl Viro return file; 3349de459215SKirill Korotaev } 33501da177e4SLinus Torvalds 3351669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3352f9652e10SAl Viro const struct open_flags *op) 335313aab428SAl Viro { 33549883d185SAl Viro struct nameidata nd; 3355f9652e10SAl Viro int flags = op->lookup_flags; 335613aab428SAl Viro struct file *filp; 335713aab428SAl Viro 33589883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3359c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 336013aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3361c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 336213aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3363c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 33649883d185SAl Viro restore_nameidata(); 336513aab428SAl Viro return filp; 336613aab428SAl Viro } 336713aab428SAl Viro 336873d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3369f9652e10SAl Viro const char *name, const struct open_flags *op) 337073d049a4SAl Viro { 33719883d185SAl Viro struct nameidata nd; 337273d049a4SAl Viro struct file *file; 337351689104SPaul Moore struct filename *filename; 3374f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 337573d049a4SAl Viro 337673d049a4SAl Viro nd.root.mnt = mnt; 337773d049a4SAl Viro nd.root.dentry = dentry; 337873d049a4SAl Viro 3379b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 338073d049a4SAl Viro return ERR_PTR(-ELOOP); 338173d049a4SAl Viro 338251689104SPaul Moore filename = getname_kernel(name); 3383a1c83681SViresh Kumar if (IS_ERR(filename)) 338451689104SPaul Moore return ERR_CAST(filename); 338551689104SPaul Moore 33869883d185SAl Viro set_nameidata(&nd, -1, filename); 3387c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 338873d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3389c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 339073d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3391c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 33929883d185SAl Viro restore_nameidata(); 339351689104SPaul Moore putname(filename); 339473d049a4SAl Viro return file; 339573d049a4SAl Viro } 339673d049a4SAl Viro 3397fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 33981ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 33991da177e4SLinus Torvalds { 3400c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3401391172c4SAl Viro struct qstr last; 3402391172c4SAl Viro int type; 3403c30dabfeSJan Kara int err2; 34041ac12b4bSJeff Layton int error; 34051ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 34061ac12b4bSJeff Layton 34071ac12b4bSJeff Layton /* 34081ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 34091ac12b4bSJeff Layton * other flags passed in are ignored! 34101ac12b4bSJeff Layton */ 34111ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 34121ac12b4bSJeff Layton 34135c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 34145c31b6ceSAl Viro if (IS_ERR(name)) 34155c31b6ceSAl Viro return ERR_CAST(name); 34161da177e4SLinus Torvalds 3417c663e5d8SChristoph Hellwig /* 3418c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3419c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3420c663e5d8SChristoph Hellwig */ 34215c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3422ed75e95dSAl Viro goto out; 3423c663e5d8SChristoph Hellwig 3424c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3425391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3426c663e5d8SChristoph Hellwig /* 3427c663e5d8SChristoph Hellwig * Do the final lookup. 3428c663e5d8SChristoph Hellwig */ 3429391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 3430391172c4SAl Viro mutex_lock_nested(&path->dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3431391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 34321da177e4SLinus Torvalds if (IS_ERR(dentry)) 3433a8104a9fSAl Viro goto unlock; 3434c663e5d8SChristoph Hellwig 3435a8104a9fSAl Viro error = -EEXIST; 3436b18825a7SDavid Howells if (d_is_positive(dentry)) 3437a8104a9fSAl Viro goto fail; 3438b18825a7SDavid Howells 3439c663e5d8SChristoph Hellwig /* 3440c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3441c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3442c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3443c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3444c663e5d8SChristoph Hellwig */ 3445391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3446a8104a9fSAl Viro error = -ENOENT; 3447ed75e95dSAl Viro goto fail; 3448e9baf6e5SAl Viro } 3449c30dabfeSJan Kara if (unlikely(err2)) { 3450c30dabfeSJan Kara error = err2; 3451a8104a9fSAl Viro goto fail; 3452c30dabfeSJan Kara } 3453181c37b6SAl Viro putname(name); 3454e9baf6e5SAl Viro return dentry; 34551da177e4SLinus Torvalds fail: 3456a8104a9fSAl Viro dput(dentry); 3457a8104a9fSAl Viro dentry = ERR_PTR(error); 3458a8104a9fSAl Viro unlock: 3459391172c4SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3460c30dabfeSJan Kara if (!err2) 3461391172c4SAl Viro mnt_drop_write(path->mnt); 3462ed75e95dSAl Viro out: 3463391172c4SAl Viro path_put(path); 3464181c37b6SAl Viro putname(name); 3465ed75e95dSAl Viro return dentry; 3466dae6ad8fSAl Viro } 3467fa14a0b8SAl Viro 3468fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3469fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3470fa14a0b8SAl Viro { 3471181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3472181c37b6SAl Viro path, lookup_flags); 3473fa14a0b8SAl Viro } 3474dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3475dae6ad8fSAl Viro 3476921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3477921a1650SAl Viro { 3478921a1650SAl Viro dput(dentry); 3479921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3480a8104a9fSAl Viro mnt_drop_write(path->mnt); 3481921a1650SAl Viro path_put(path); 3482921a1650SAl Viro } 3483921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3484921a1650SAl Viro 3485520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 34861ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3487dae6ad8fSAl Viro { 3488181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3489dae6ad8fSAl Viro } 3490dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3491dae6ad8fSAl Viro 34921a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 34931da177e4SLinus Torvalds { 3494a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 34951da177e4SLinus Torvalds 34961da177e4SLinus Torvalds if (error) 34971da177e4SLinus Torvalds return error; 34981da177e4SLinus Torvalds 3499975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 35001da177e4SLinus Torvalds return -EPERM; 35011da177e4SLinus Torvalds 3502acfa4380SAl Viro if (!dir->i_op->mknod) 35031da177e4SLinus Torvalds return -EPERM; 35041da177e4SLinus Torvalds 350508ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 350608ce5f16SSerge E. Hallyn if (error) 350708ce5f16SSerge E. Hallyn return error; 350808ce5f16SSerge E. Hallyn 35091da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 35101da177e4SLinus Torvalds if (error) 35111da177e4SLinus Torvalds return error; 35121da177e4SLinus Torvalds 35131da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3514a74574aaSStephen Smalley if (!error) 3515f38aa942SAmy Griffis fsnotify_create(dir, dentry); 35161da177e4SLinus Torvalds return error; 35171da177e4SLinus Torvalds } 35184d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 35191da177e4SLinus Torvalds 3520f69aac00SAl Viro static int may_mknod(umode_t mode) 3521463c3197SDave Hansen { 3522463c3197SDave Hansen switch (mode & S_IFMT) { 3523463c3197SDave Hansen case S_IFREG: 3524463c3197SDave Hansen case S_IFCHR: 3525463c3197SDave Hansen case S_IFBLK: 3526463c3197SDave Hansen case S_IFIFO: 3527463c3197SDave Hansen case S_IFSOCK: 3528463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3529463c3197SDave Hansen return 0; 3530463c3197SDave Hansen case S_IFDIR: 3531463c3197SDave Hansen return -EPERM; 3532463c3197SDave Hansen default: 3533463c3197SDave Hansen return -EINVAL; 3534463c3197SDave Hansen } 3535463c3197SDave Hansen } 3536463c3197SDave Hansen 35378208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 35382e4d0924SHeiko Carstens unsigned, dev) 35391da177e4SLinus Torvalds { 35401da177e4SLinus Torvalds struct dentry *dentry; 3541dae6ad8fSAl Viro struct path path; 3542dae6ad8fSAl Viro int error; 3543972567f1SJeff Layton unsigned int lookup_flags = 0; 35441da177e4SLinus Torvalds 35458e4bfca1SAl Viro error = may_mknod(mode); 35468e4bfca1SAl Viro if (error) 35478e4bfca1SAl Viro return error; 3548972567f1SJeff Layton retry: 3549972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3550dae6ad8fSAl Viro if (IS_ERR(dentry)) 3551dae6ad8fSAl Viro return PTR_ERR(dentry); 35522ad94ae6SAl Viro 3553dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3554ce3b0f8dSAl Viro mode &= ~current_umask(); 3555dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3556be6d3e56SKentaro Takeda if (error) 3557a8104a9fSAl Viro goto out; 35581da177e4SLinus Torvalds switch (mode & S_IFMT) { 35591da177e4SLinus Torvalds case 0: case S_IFREG: 3560312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 35611da177e4SLinus Torvalds break; 35621da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3563dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 35641da177e4SLinus Torvalds new_decode_dev(dev)); 35651da177e4SLinus Torvalds break; 35661da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3567dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 35681da177e4SLinus Torvalds break; 35691da177e4SLinus Torvalds } 3570a8104a9fSAl Viro out: 3571921a1650SAl Viro done_path_create(&path, dentry); 3572972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3573972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3574972567f1SJeff Layton goto retry; 3575972567f1SJeff Layton } 35761da177e4SLinus Torvalds return error; 35771da177e4SLinus Torvalds } 35781da177e4SLinus Torvalds 35798208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 35805590ff0dSUlrich Drepper { 35815590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 35825590ff0dSUlrich Drepper } 35835590ff0dSUlrich Drepper 358418bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 35851da177e4SLinus Torvalds { 3586a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35878de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 35881da177e4SLinus Torvalds 35891da177e4SLinus Torvalds if (error) 35901da177e4SLinus Torvalds return error; 35911da177e4SLinus Torvalds 3592acfa4380SAl Viro if (!dir->i_op->mkdir) 35931da177e4SLinus Torvalds return -EPERM; 35941da177e4SLinus Torvalds 35951da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 35961da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 35971da177e4SLinus Torvalds if (error) 35981da177e4SLinus Torvalds return error; 35991da177e4SLinus Torvalds 36008de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 36018de52778SAl Viro return -EMLINK; 36028de52778SAl Viro 36031da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3604a74574aaSStephen Smalley if (!error) 3605f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 36061da177e4SLinus Torvalds return error; 36071da177e4SLinus Torvalds } 36084d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 36091da177e4SLinus Torvalds 3610a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 36111da177e4SLinus Torvalds { 36126902d925SDave Hansen struct dentry *dentry; 3613dae6ad8fSAl Viro struct path path; 3614dae6ad8fSAl Viro int error; 3615b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 36161da177e4SLinus Torvalds 3617b76d8b82SJeff Layton retry: 3618b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 36196902d925SDave Hansen if (IS_ERR(dentry)) 3620dae6ad8fSAl Viro return PTR_ERR(dentry); 36216902d925SDave Hansen 3622dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3623ce3b0f8dSAl Viro mode &= ~current_umask(); 3624dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3625a8104a9fSAl Viro if (!error) 3626dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3627921a1650SAl Viro done_path_create(&path, dentry); 3628b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3629b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3630b76d8b82SJeff Layton goto retry; 3631b76d8b82SJeff Layton } 36321da177e4SLinus Torvalds return error; 36331da177e4SLinus Torvalds } 36341da177e4SLinus Torvalds 3635a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 36365590ff0dSUlrich Drepper { 36375590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 36385590ff0dSUlrich Drepper } 36395590ff0dSUlrich Drepper 36401da177e4SLinus Torvalds /* 3641a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3642c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3643a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3644a71905f0SSage Weil * then we drop the dentry now. 36451da177e4SLinus Torvalds * 36461da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 36471da177e4SLinus Torvalds * do a 36481da177e4SLinus Torvalds * 36491da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 36501da177e4SLinus Torvalds * return -EBUSY; 36511da177e4SLinus Torvalds * 36521da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 36531da177e4SLinus Torvalds * that is still in use by something else.. 36541da177e4SLinus Torvalds */ 36551da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 36561da177e4SLinus Torvalds { 36571da177e4SLinus Torvalds shrink_dcache_parent(dentry); 36581da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 365998474236SWaiman Long if (dentry->d_lockref.count == 1) 36601da177e4SLinus Torvalds __d_drop(dentry); 36611da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 36621da177e4SLinus Torvalds } 36634d359507SAl Viro EXPORT_SYMBOL(dentry_unhash); 36641da177e4SLinus Torvalds 36651da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 36661da177e4SLinus Torvalds { 36671da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 36681da177e4SLinus Torvalds 36691da177e4SLinus Torvalds if (error) 36701da177e4SLinus Torvalds return error; 36711da177e4SLinus Torvalds 3672acfa4380SAl Viro if (!dir->i_op->rmdir) 36731da177e4SLinus Torvalds return -EPERM; 36741da177e4SLinus Torvalds 36751d2ef590SAl Viro dget(dentry); 36761b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3677912dbc15SSage Weil 36781da177e4SLinus Torvalds error = -EBUSY; 36797af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3680912dbc15SSage Weil goto out; 3681912dbc15SSage Weil 36821da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3683912dbc15SSage Weil if (error) 3684912dbc15SSage Weil goto out; 3685912dbc15SSage Weil 36863cebde24SSage Weil shrink_dcache_parent(dentry); 36871da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3688912dbc15SSage Weil if (error) 3689912dbc15SSage Weil goto out; 3690912dbc15SSage Weil 36911da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3692d83c49f3SAl Viro dont_mount(dentry); 36938ed936b5SEric W. Biederman detach_mounts(dentry); 36941da177e4SLinus Torvalds 3695912dbc15SSage Weil out: 3696912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 36971d2ef590SAl Viro dput(dentry); 3698912dbc15SSage Weil if (!error) 3699912dbc15SSage Weil d_delete(dentry); 37001da177e4SLinus Torvalds return error; 37011da177e4SLinus Torvalds } 37024d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 37031da177e4SLinus Torvalds 37045590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 37051da177e4SLinus Torvalds { 37061da177e4SLinus Torvalds int error = 0; 370791a27b2aSJeff Layton struct filename *name; 37081da177e4SLinus Torvalds struct dentry *dentry; 3709f5beed75SAl Viro struct path path; 3710f5beed75SAl Viro struct qstr last; 3711f5beed75SAl Viro int type; 3712c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3713c6ee9206SJeff Layton retry: 3714f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3715f5beed75SAl Viro &path, &last, &type, lookup_flags); 371691a27b2aSJeff Layton if (IS_ERR(name)) 371791a27b2aSJeff Layton return PTR_ERR(name); 37181da177e4SLinus Torvalds 3719f5beed75SAl Viro switch (type) { 37201da177e4SLinus Torvalds case LAST_DOTDOT: 37211da177e4SLinus Torvalds error = -ENOTEMPTY; 37221da177e4SLinus Torvalds goto exit1; 37231da177e4SLinus Torvalds case LAST_DOT: 37241da177e4SLinus Torvalds error = -EINVAL; 37251da177e4SLinus Torvalds goto exit1; 37261da177e4SLinus Torvalds case LAST_ROOT: 37271da177e4SLinus Torvalds error = -EBUSY; 37281da177e4SLinus Torvalds goto exit1; 37291da177e4SLinus Torvalds } 37300612d9fbSOGAWA Hirofumi 3731f5beed75SAl Viro error = mnt_want_write(path.mnt); 3732c30dabfeSJan Kara if (error) 3733c30dabfeSJan Kara goto exit1; 37340612d9fbSOGAWA Hirofumi 3735f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3736f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 37371da177e4SLinus Torvalds error = PTR_ERR(dentry); 37386902d925SDave Hansen if (IS_ERR(dentry)) 37396902d925SDave Hansen goto exit2; 3740e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3741e6bc45d6STheodore Ts'o error = -ENOENT; 3742e6bc45d6STheodore Ts'o goto exit3; 3743e6bc45d6STheodore Ts'o } 3744f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3745be6d3e56SKentaro Takeda if (error) 3746c30dabfeSJan Kara goto exit3; 3747f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 37480622753bSDave Hansen exit3: 37491da177e4SLinus Torvalds dput(dentry); 37506902d925SDave Hansen exit2: 3751f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 3752f5beed75SAl Viro mnt_drop_write(path.mnt); 37531da177e4SLinus Torvalds exit1: 3754f5beed75SAl Viro path_put(&path); 37551da177e4SLinus Torvalds putname(name); 3756c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3757c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3758c6ee9206SJeff Layton goto retry; 3759c6ee9206SJeff Layton } 37601da177e4SLinus Torvalds return error; 37611da177e4SLinus Torvalds } 37621da177e4SLinus Torvalds 37633cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 37645590ff0dSUlrich Drepper { 37655590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 37665590ff0dSUlrich Drepper } 37675590ff0dSUlrich Drepper 3768b21996e3SJ. Bruce Fields /** 3769b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3770b21996e3SJ. Bruce Fields * @dir: parent directory 3771b21996e3SJ. Bruce Fields * @dentry: victim 3772b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3773b21996e3SJ. Bruce Fields * 3774b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3775b21996e3SJ. Bruce Fields * 3776b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3777b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3778b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3779b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3780b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3781b21996e3SJ. Bruce Fields * 3782b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3783b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3784b21996e3SJ. Bruce Fields * to be NFS exported. 3785b21996e3SJ. Bruce Fields */ 3786b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 37871da177e4SLinus Torvalds { 37889accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 37891da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 37901da177e4SLinus Torvalds 37911da177e4SLinus Torvalds if (error) 37921da177e4SLinus Torvalds return error; 37931da177e4SLinus Torvalds 3794acfa4380SAl Viro if (!dir->i_op->unlink) 37951da177e4SLinus Torvalds return -EPERM; 37961da177e4SLinus Torvalds 37979accbb97SJ. Bruce Fields mutex_lock(&target->i_mutex); 37988ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 37991da177e4SLinus Torvalds error = -EBUSY; 38001da177e4SLinus Torvalds else { 38011da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3802bec1052eSAl Viro if (!error) { 38035a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 38045a14696cSJ. Bruce Fields if (error) 3805b21996e3SJ. Bruce Fields goto out; 38061da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 38078ed936b5SEric W. Biederman if (!error) { 3808d83c49f3SAl Viro dont_mount(dentry); 38098ed936b5SEric W. Biederman detach_mounts(dentry); 38108ed936b5SEric W. Biederman } 3811bec1052eSAl Viro } 38121da177e4SLinus Torvalds } 3813b21996e3SJ. Bruce Fields out: 38149accbb97SJ. Bruce Fields mutex_unlock(&target->i_mutex); 38151da177e4SLinus Torvalds 38161da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 38171da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 38189accbb97SJ. Bruce Fields fsnotify_link_count(target); 38191da177e4SLinus Torvalds d_delete(dentry); 38201da177e4SLinus Torvalds } 38210eeca283SRobert Love 38221da177e4SLinus Torvalds return error; 38231da177e4SLinus Torvalds } 38244d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 38251da177e4SLinus Torvalds 38261da177e4SLinus Torvalds /* 38271da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 38281b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 38291da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 38301da177e4SLinus Torvalds * while waiting on the I/O. 38311da177e4SLinus Torvalds */ 38325590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 38331da177e4SLinus Torvalds { 38342ad94ae6SAl Viro int error; 383591a27b2aSJeff Layton struct filename *name; 38361da177e4SLinus Torvalds struct dentry *dentry; 3837f5beed75SAl Viro struct path path; 3838f5beed75SAl Viro struct qstr last; 3839f5beed75SAl Viro int type; 38401da177e4SLinus Torvalds struct inode *inode = NULL; 3841b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 38425d18f813SJeff Layton unsigned int lookup_flags = 0; 38435d18f813SJeff Layton retry: 3844f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3845f5beed75SAl Viro &path, &last, &type, lookup_flags); 384691a27b2aSJeff Layton if (IS_ERR(name)) 384791a27b2aSJeff Layton return PTR_ERR(name); 38482ad94ae6SAl Viro 38491da177e4SLinus Torvalds error = -EISDIR; 3850f5beed75SAl Viro if (type != LAST_NORM) 38511da177e4SLinus Torvalds goto exit1; 38520612d9fbSOGAWA Hirofumi 3853f5beed75SAl Viro error = mnt_want_write(path.mnt); 3854c30dabfeSJan Kara if (error) 3855c30dabfeSJan Kara goto exit1; 3856b21996e3SJ. Bruce Fields retry_deleg: 3857f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3858f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38591da177e4SLinus Torvalds error = PTR_ERR(dentry); 38601da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 38611da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3862f5beed75SAl Viro if (last.name[last.len]) 386350338b88STörök Edwin goto slashes; 38641da177e4SLinus Torvalds inode = dentry->d_inode; 3865b18825a7SDavid Howells if (d_is_negative(dentry)) 3866e6bc45d6STheodore Ts'o goto slashes; 38677de9c6eeSAl Viro ihold(inode); 3868f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3869be6d3e56SKentaro Takeda if (error) 3870c30dabfeSJan Kara goto exit2; 3871f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 38721da177e4SLinus Torvalds exit2: 38731da177e4SLinus Torvalds dput(dentry); 38741da177e4SLinus Torvalds } 3875f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 38761da177e4SLinus Torvalds if (inode) 38771da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3878b21996e3SJ. Bruce Fields inode = NULL; 3879b21996e3SJ. Bruce Fields if (delegated_inode) { 38805a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3881b21996e3SJ. Bruce Fields if (!error) 3882b21996e3SJ. Bruce Fields goto retry_deleg; 3883b21996e3SJ. Bruce Fields } 3884f5beed75SAl Viro mnt_drop_write(path.mnt); 38851da177e4SLinus Torvalds exit1: 3886f5beed75SAl Viro path_put(&path); 38871da177e4SLinus Torvalds putname(name); 38885d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 38895d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 38905d18f813SJeff Layton inode = NULL; 38915d18f813SJeff Layton goto retry; 38925d18f813SJeff Layton } 38931da177e4SLinus Torvalds return error; 38941da177e4SLinus Torvalds 38951da177e4SLinus Torvalds slashes: 3896b18825a7SDavid Howells if (d_is_negative(dentry)) 3897b18825a7SDavid Howells error = -ENOENT; 389844b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3899b18825a7SDavid Howells error = -EISDIR; 3900b18825a7SDavid Howells else 3901b18825a7SDavid Howells error = -ENOTDIR; 39021da177e4SLinus Torvalds goto exit2; 39031da177e4SLinus Torvalds } 39041da177e4SLinus Torvalds 39052e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 39065590ff0dSUlrich Drepper { 39075590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 39085590ff0dSUlrich Drepper return -EINVAL; 39095590ff0dSUlrich Drepper 39105590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 39115590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 39125590ff0dSUlrich Drepper 39135590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 39145590ff0dSUlrich Drepper } 39155590ff0dSUlrich Drepper 39163480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 39175590ff0dSUlrich Drepper { 39185590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 39195590ff0dSUlrich Drepper } 39205590ff0dSUlrich Drepper 3921db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 39221da177e4SLinus Torvalds { 3923a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 39241da177e4SLinus Torvalds 39251da177e4SLinus Torvalds if (error) 39261da177e4SLinus Torvalds return error; 39271da177e4SLinus Torvalds 3928acfa4380SAl Viro if (!dir->i_op->symlink) 39291da177e4SLinus Torvalds return -EPERM; 39301da177e4SLinus Torvalds 39311da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 39321da177e4SLinus Torvalds if (error) 39331da177e4SLinus Torvalds return error; 39341da177e4SLinus Torvalds 39351da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3936a74574aaSStephen Smalley if (!error) 3937f38aa942SAmy Griffis fsnotify_create(dir, dentry); 39381da177e4SLinus Torvalds return error; 39391da177e4SLinus Torvalds } 39404d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 39411da177e4SLinus Torvalds 39422e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 39432e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 39441da177e4SLinus Torvalds { 39452ad94ae6SAl Viro int error; 394691a27b2aSJeff Layton struct filename *from; 39476902d925SDave Hansen struct dentry *dentry; 3948dae6ad8fSAl Viro struct path path; 3949f46d3567SJeff Layton unsigned int lookup_flags = 0; 39501da177e4SLinus Torvalds 39511da177e4SLinus Torvalds from = getname(oldname); 39521da177e4SLinus Torvalds if (IS_ERR(from)) 39531da177e4SLinus Torvalds return PTR_ERR(from); 3954f46d3567SJeff Layton retry: 3955f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 39561da177e4SLinus Torvalds error = PTR_ERR(dentry); 39576902d925SDave Hansen if (IS_ERR(dentry)) 3958dae6ad8fSAl Viro goto out_putname; 39596902d925SDave Hansen 396091a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3961a8104a9fSAl Viro if (!error) 396291a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3963921a1650SAl Viro done_path_create(&path, dentry); 3964f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 3965f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 3966f46d3567SJeff Layton goto retry; 3967f46d3567SJeff Layton } 39686902d925SDave Hansen out_putname: 39691da177e4SLinus Torvalds putname(from); 39701da177e4SLinus Torvalds return error; 39711da177e4SLinus Torvalds } 39721da177e4SLinus Torvalds 39733480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 39745590ff0dSUlrich Drepper { 39755590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 39765590ff0dSUlrich Drepper } 39775590ff0dSUlrich Drepper 3978146a8595SJ. Bruce Fields /** 3979146a8595SJ. Bruce Fields * vfs_link - create a new link 3980146a8595SJ. Bruce Fields * @old_dentry: object to be linked 3981146a8595SJ. Bruce Fields * @dir: new parent 3982146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 3983146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 3984146a8595SJ. Bruce Fields * 3985146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 3986146a8595SJ. Bruce Fields * 3987146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 3988146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 3989146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 3990146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 3991146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 3992146a8595SJ. Bruce Fields * 3993146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3994146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3995146a8595SJ. Bruce Fields * to be NFS exported. 3996146a8595SJ. Bruce Fields */ 3997146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 39981da177e4SLinus Torvalds { 39991da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 40008de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 40011da177e4SLinus Torvalds int error; 40021da177e4SLinus Torvalds 40031da177e4SLinus Torvalds if (!inode) 40041da177e4SLinus Torvalds return -ENOENT; 40051da177e4SLinus Torvalds 4006a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 40071da177e4SLinus Torvalds if (error) 40081da177e4SLinus Torvalds return error; 40091da177e4SLinus Torvalds 40101da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 40111da177e4SLinus Torvalds return -EXDEV; 40121da177e4SLinus Torvalds 40131da177e4SLinus Torvalds /* 40141da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 40151da177e4SLinus Torvalds */ 40161da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 40171da177e4SLinus Torvalds return -EPERM; 4018acfa4380SAl Viro if (!dir->i_op->link) 40191da177e4SLinus Torvalds return -EPERM; 40207e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 40211da177e4SLinus Torvalds return -EPERM; 40221da177e4SLinus Torvalds 40231da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 40241da177e4SLinus Torvalds if (error) 40251da177e4SLinus Torvalds return error; 40261da177e4SLinus Torvalds 40277e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 4028aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4029f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4030aae8a97dSAneesh Kumar K.V error = -ENOENT; 40318de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 40328de52778SAl Viro error = -EMLINK; 4033146a8595SJ. Bruce Fields else { 4034146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4035146a8595SJ. Bruce Fields if (!error) 40361da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4037146a8595SJ. Bruce Fields } 4038f4e0c30cSAl Viro 4039f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4040f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4041f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4042f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4043f4e0c30cSAl Viro } 40447e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 4045e31e14ecSStephen Smalley if (!error) 40467e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 40471da177e4SLinus Torvalds return error; 40481da177e4SLinus Torvalds } 40494d359507SAl Viro EXPORT_SYMBOL(vfs_link); 40501da177e4SLinus Torvalds 40511da177e4SLinus Torvalds /* 40521da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 40531da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 40541da177e4SLinus Torvalds * newname. --KAB 40551da177e4SLinus Torvalds * 40561da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 40571da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 40581da177e4SLinus Torvalds * and other special files. --ADM 40591da177e4SLinus Torvalds */ 40602e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 40612e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 40621da177e4SLinus Torvalds { 40631da177e4SLinus Torvalds struct dentry *new_dentry; 4064dae6ad8fSAl Viro struct path old_path, new_path; 4065146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 406611a7b371SAneesh Kumar K.V int how = 0; 40671da177e4SLinus Torvalds int error; 40681da177e4SLinus Torvalds 406911a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4070c04030e1SUlrich Drepper return -EINVAL; 407111a7b371SAneesh Kumar K.V /* 4072f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4073f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4074f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 407511a7b371SAneesh Kumar K.V */ 4076f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4077f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4078f0cc6ffbSLinus Torvalds return -ENOENT; 407911a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4080f0cc6ffbSLinus Torvalds } 4081c04030e1SUlrich Drepper 408211a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 408311a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4084442e31caSJeff Layton retry: 408511a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 40861da177e4SLinus Torvalds if (error) 40872ad94ae6SAl Viro return error; 40882ad94ae6SAl Viro 4089442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4090442e31caSJeff Layton (how & LOOKUP_REVAL)); 40911da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 40926902d925SDave Hansen if (IS_ERR(new_dentry)) 4093dae6ad8fSAl Viro goto out; 4094dae6ad8fSAl Viro 4095dae6ad8fSAl Viro error = -EXDEV; 4096dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4097dae6ad8fSAl Viro goto out_dput; 4098800179c9SKees Cook error = may_linkat(&old_path); 4099800179c9SKees Cook if (unlikely(error)) 4100800179c9SKees Cook goto out_dput; 4101dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4102be6d3e56SKentaro Takeda if (error) 4103a8104a9fSAl Viro goto out_dput; 4104146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 410575c3f29dSDave Hansen out_dput: 4106921a1650SAl Viro done_path_create(&new_path, new_dentry); 4107146a8595SJ. Bruce Fields if (delegated_inode) { 4108146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4109d22e6338SOleg Drokin if (!error) { 4110d22e6338SOleg Drokin path_put(&old_path); 4111146a8595SJ. Bruce Fields goto retry; 4112146a8595SJ. Bruce Fields } 4113d22e6338SOleg Drokin } 4114442e31caSJeff Layton if (retry_estale(error, how)) { 4115d22e6338SOleg Drokin path_put(&old_path); 4116442e31caSJeff Layton how |= LOOKUP_REVAL; 4117442e31caSJeff Layton goto retry; 4118442e31caSJeff Layton } 41191da177e4SLinus Torvalds out: 41202d8f3038SAl Viro path_put(&old_path); 41211da177e4SLinus Torvalds 41221da177e4SLinus Torvalds return error; 41231da177e4SLinus Torvalds } 41241da177e4SLinus Torvalds 41253480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 41265590ff0dSUlrich Drepper { 4127c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 41285590ff0dSUlrich Drepper } 41295590ff0dSUlrich Drepper 4130bc27027aSMiklos Szeredi /** 4131bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4132bc27027aSMiklos Szeredi * @old_dir: parent of source 4133bc27027aSMiklos Szeredi * @old_dentry: source 4134bc27027aSMiklos Szeredi * @new_dir: parent of destination 4135bc27027aSMiklos Szeredi * @new_dentry: destination 4136bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4137520c8b16SMiklos Szeredi * @flags: rename flags 4138bc27027aSMiklos Szeredi * 4139bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4140bc27027aSMiklos Szeredi * 4141bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4142bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4143bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4144bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4145bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4146bc27027aSMiklos Szeredi * so. 4147bc27027aSMiklos Szeredi * 4148bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4149bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4150bc27027aSMiklos Szeredi * to be NFS exported. 4151bc27027aSMiklos Szeredi * 41521da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 41531da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 41541da177e4SLinus Torvalds * Problems: 4155d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 41561da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 41571da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4158a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 41591da177e4SLinus Torvalds * story. 41606cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 41616cedba89SJ. Bruce Fields * and source (if it is not a directory). 41621b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 41631da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 41641da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4165a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 41661da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 41671da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 41681da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4169a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 41701da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 41711da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 41721da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4173e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 41741b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 41751da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4176c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 41771da177e4SLinus Torvalds * locking]. 41781da177e4SLinus Torvalds */ 41791da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 41808e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4181520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 41821da177e4SLinus Torvalds { 41831da177e4SLinus Torvalds int error; 4184bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 418559b0df21SEric Paris const unsigned char *old_name; 4186bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4187bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4188da1ce067SMiklos Szeredi bool new_is_dir = false; 4189da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 41901da177e4SLinus Torvalds 4191bc27027aSMiklos Szeredi if (source == target) 41921da177e4SLinus Torvalds return 0; 41931da177e4SLinus Torvalds 41941da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 41951da177e4SLinus Torvalds if (error) 41961da177e4SLinus Torvalds return error; 41971da177e4SLinus Torvalds 4198da1ce067SMiklos Szeredi if (!target) { 4199a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4200da1ce067SMiklos Szeredi } else { 4201da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4202da1ce067SMiklos Szeredi 4203da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 42041da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4205da1ce067SMiklos Szeredi else 4206da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4207da1ce067SMiklos Szeredi } 42081da177e4SLinus Torvalds if (error) 42091da177e4SLinus Torvalds return error; 42101da177e4SLinus Torvalds 42117177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 42121da177e4SLinus Torvalds return -EPERM; 42131da177e4SLinus Torvalds 4214520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4215520c8b16SMiklos Szeredi return -EINVAL; 4216520c8b16SMiklos Szeredi 4217bc27027aSMiklos Szeredi /* 4218bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4219bc27027aSMiklos Szeredi * we'll need to flip '..'. 4220bc27027aSMiklos Szeredi */ 4221da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4222da1ce067SMiklos Szeredi if (is_dir) { 4223bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4224bc27027aSMiklos Szeredi if (error) 4225bc27027aSMiklos Szeredi return error; 4226bc27027aSMiklos Szeredi } 4227da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4228da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4229da1ce067SMiklos Szeredi if (error) 4230da1ce067SMiklos Szeredi return error; 4231da1ce067SMiklos Szeredi } 4232da1ce067SMiklos Szeredi } 42330eeca283SRobert Love 42340b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 42350b3974ebSMiklos Szeredi flags); 4236bc27027aSMiklos Szeredi if (error) 4237bc27027aSMiklos Szeredi return error; 4238bc27027aSMiklos Szeredi 4239bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4240bc27027aSMiklos Szeredi dget(new_dentry); 4241da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4242bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4243bc27027aSMiklos Szeredi else if (target) 4244bc27027aSMiklos Szeredi mutex_lock(&target->i_mutex); 4245bc27027aSMiklos Szeredi 4246bc27027aSMiklos Szeredi error = -EBUSY; 42477af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4248bc27027aSMiklos Szeredi goto out; 4249bc27027aSMiklos Szeredi 4250da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4251bc27027aSMiklos Szeredi error = -EMLINK; 4252da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4253bc27027aSMiklos Szeredi goto out; 4254da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4255da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4256da1ce067SMiklos Szeredi goto out; 4257da1ce067SMiklos Szeredi } 4258da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4259bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4260da1ce067SMiklos Szeredi if (!is_dir) { 4261bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4262bc27027aSMiklos Szeredi if (error) 4263bc27027aSMiklos Szeredi goto out; 4264da1ce067SMiklos Szeredi } 4265da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4266bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4267bc27027aSMiklos Szeredi if (error) 4268bc27027aSMiklos Szeredi goto out; 4269bc27027aSMiklos Szeredi } 42707177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4271520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4272520c8b16SMiklos Szeredi new_dir, new_dentry); 4273520c8b16SMiklos Szeredi } else { 42747177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4275520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4276520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4277520c8b16SMiklos Szeredi } 4278bc27027aSMiklos Szeredi if (error) 4279bc27027aSMiklos Szeredi goto out; 4280bc27027aSMiklos Szeredi 4281da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 42821da177e4SLinus Torvalds if (is_dir) 4283bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4284bc27027aSMiklos Szeredi dont_mount(new_dentry); 42858ed936b5SEric W. Biederman detach_mounts(new_dentry); 4286bc27027aSMiklos Szeredi } 4287da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4288da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4289bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4290da1ce067SMiklos Szeredi else 4291da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4292da1ce067SMiklos Szeredi } 4293bc27027aSMiklos Szeredi out: 4294da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4295bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4296bc27027aSMiklos Szeredi else if (target) 4297bc27027aSMiklos Szeredi mutex_unlock(&target->i_mutex); 4298bc27027aSMiklos Szeredi dput(new_dentry); 4299da1ce067SMiklos Szeredi if (!error) { 4300123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4301da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4302da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4303da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4304da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4305da1ce067SMiklos Szeredi } 4306da1ce067SMiklos Szeredi } 43070eeca283SRobert Love fsnotify_oldname_free(old_name); 43080eeca283SRobert Love 43091da177e4SLinus Torvalds return error; 43101da177e4SLinus Torvalds } 43114d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 43121da177e4SLinus Torvalds 4313520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4314520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 43151da177e4SLinus Torvalds { 43161da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 43171da177e4SLinus Torvalds struct dentry *trap; 4318f5beed75SAl Viro struct path old_path, new_path; 4319f5beed75SAl Viro struct qstr old_last, new_last; 4320f5beed75SAl Viro int old_type, new_type; 43218e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 432291a27b2aSJeff Layton struct filename *from; 432391a27b2aSJeff Layton struct filename *to; 4324f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4325c6a94284SJeff Layton bool should_retry = false; 43262ad94ae6SAl Viro int error; 4327520c8b16SMiklos Szeredi 43280d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4329da1ce067SMiklos Szeredi return -EINVAL; 4330da1ce067SMiklos Szeredi 43310d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 43320d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4333520c8b16SMiklos Szeredi return -EINVAL; 4334520c8b16SMiklos Szeredi 43350d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 43360d7a8555SMiklos Szeredi return -EPERM; 43370d7a8555SMiklos Szeredi 4338f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4339f5beed75SAl Viro target_flags = 0; 4340f5beed75SAl Viro 4341c6a94284SJeff Layton retry: 4342f5beed75SAl Viro from = user_path_parent(olddfd, oldname, 4343f5beed75SAl Viro &old_path, &old_last, &old_type, lookup_flags); 434491a27b2aSJeff Layton if (IS_ERR(from)) { 434591a27b2aSJeff Layton error = PTR_ERR(from); 43461da177e4SLinus Torvalds goto exit; 434791a27b2aSJeff Layton } 43481da177e4SLinus Torvalds 4349f5beed75SAl Viro to = user_path_parent(newdfd, newname, 4350f5beed75SAl Viro &new_path, &new_last, &new_type, lookup_flags); 435191a27b2aSJeff Layton if (IS_ERR(to)) { 435291a27b2aSJeff Layton error = PTR_ERR(to); 43531da177e4SLinus Torvalds goto exit1; 435491a27b2aSJeff Layton } 43551da177e4SLinus Torvalds 43561da177e4SLinus Torvalds error = -EXDEV; 4357f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 43581da177e4SLinus Torvalds goto exit2; 43591da177e4SLinus Torvalds 43601da177e4SLinus Torvalds error = -EBUSY; 4361f5beed75SAl Viro if (old_type != LAST_NORM) 43621da177e4SLinus Torvalds goto exit2; 43631da177e4SLinus Torvalds 43640a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 43650a7c3937SMiklos Szeredi error = -EEXIST; 4366f5beed75SAl Viro if (new_type != LAST_NORM) 43671da177e4SLinus Torvalds goto exit2; 43681da177e4SLinus Torvalds 4369f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4370c30dabfeSJan Kara if (error) 4371c30dabfeSJan Kara goto exit2; 4372c30dabfeSJan Kara 43738e6d782cSJ. Bruce Fields retry_deleg: 4374f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 43751da177e4SLinus Torvalds 4376f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 43771da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 43781da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 43791da177e4SLinus Torvalds goto exit3; 43801da177e4SLinus Torvalds /* source must exist */ 43811da177e4SLinus Torvalds error = -ENOENT; 4382b18825a7SDavid Howells if (d_is_negative(old_dentry)) 43831da177e4SLinus Torvalds goto exit4; 4384f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 43851da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 43861da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 43871da177e4SLinus Torvalds goto exit4; 43880a7c3937SMiklos Szeredi error = -EEXIST; 43890a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 43900a7c3937SMiklos Szeredi goto exit5; 4391da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4392da1ce067SMiklos Szeredi error = -ENOENT; 4393da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4394da1ce067SMiklos Szeredi goto exit5; 4395da1ce067SMiklos Szeredi 4396da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4397da1ce067SMiklos Szeredi error = -ENOTDIR; 4398f5beed75SAl Viro if (new_last.name[new_last.len]) 4399da1ce067SMiklos Szeredi goto exit5; 4400da1ce067SMiklos Szeredi } 4401da1ce067SMiklos Szeredi } 44020a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 44030a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 44040a7c3937SMiklos Szeredi error = -ENOTDIR; 4405f5beed75SAl Viro if (old_last.name[old_last.len]) 44060a7c3937SMiklos Szeredi goto exit5; 4407f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 44080a7c3937SMiklos Szeredi goto exit5; 44090a7c3937SMiklos Szeredi } 44100a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 44110a7c3937SMiklos Szeredi error = -EINVAL; 44120a7c3937SMiklos Szeredi if (old_dentry == trap) 44130a7c3937SMiklos Szeredi goto exit5; 44141da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4415da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 44161da177e4SLinus Torvalds error = -ENOTEMPTY; 44171da177e4SLinus Torvalds if (new_dentry == trap) 44181da177e4SLinus Torvalds goto exit5; 44191da177e4SLinus Torvalds 4420f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4421f5beed75SAl Viro &new_path, new_dentry, flags); 4422be6d3e56SKentaro Takeda if (error) 4423c30dabfeSJan Kara goto exit5; 4424f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4425f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4426520c8b16SMiklos Szeredi &delegated_inode, flags); 44271da177e4SLinus Torvalds exit5: 44281da177e4SLinus Torvalds dput(new_dentry); 44291da177e4SLinus Torvalds exit4: 44301da177e4SLinus Torvalds dput(old_dentry); 44311da177e4SLinus Torvalds exit3: 4432f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 44338e6d782cSJ. Bruce Fields if (delegated_inode) { 44348e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 44358e6d782cSJ. Bruce Fields if (!error) 44368e6d782cSJ. Bruce Fields goto retry_deleg; 44378e6d782cSJ. Bruce Fields } 4438f5beed75SAl Viro mnt_drop_write(old_path.mnt); 44391da177e4SLinus Torvalds exit2: 4440c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4441c6a94284SJeff Layton should_retry = true; 4442f5beed75SAl Viro path_put(&new_path); 44432ad94ae6SAl Viro putname(to); 44441da177e4SLinus Torvalds exit1: 4445f5beed75SAl Viro path_put(&old_path); 44461da177e4SLinus Torvalds putname(from); 4447c6a94284SJeff Layton if (should_retry) { 4448c6a94284SJeff Layton should_retry = false; 4449c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4450c6a94284SJeff Layton goto retry; 4451c6a94284SJeff Layton } 44522ad94ae6SAl Viro exit: 44531da177e4SLinus Torvalds return error; 44541da177e4SLinus Torvalds } 44551da177e4SLinus Torvalds 4456520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4457520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4458520c8b16SMiklos Szeredi { 4459520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4460520c8b16SMiklos Szeredi } 4461520c8b16SMiklos Szeredi 4462a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 44635590ff0dSUlrich Drepper { 4464520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 44655590ff0dSUlrich Drepper } 44665590ff0dSUlrich Drepper 4467787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4468787fb6bcSMiklos Szeredi { 4469787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4470787fb6bcSMiklos Szeredi if (error) 4471787fb6bcSMiklos Szeredi return error; 4472787fb6bcSMiklos Szeredi 4473787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4474787fb6bcSMiklos Szeredi return -EPERM; 4475787fb6bcSMiklos Szeredi 4476787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4477787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4478787fb6bcSMiklos Szeredi } 4479787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4480787fb6bcSMiklos Szeredi 44815d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 44821da177e4SLinus Torvalds { 44835d826c84SAl Viro int len = PTR_ERR(link); 44841da177e4SLinus Torvalds if (IS_ERR(link)) 44851da177e4SLinus Torvalds goto out; 44861da177e4SLinus Torvalds 44871da177e4SLinus Torvalds len = strlen(link); 44881da177e4SLinus Torvalds if (len > (unsigned) buflen) 44891da177e4SLinus Torvalds len = buflen; 44901da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 44911da177e4SLinus Torvalds len = -EFAULT; 44921da177e4SLinus Torvalds out: 44931da177e4SLinus Torvalds return len; 44941da177e4SLinus Torvalds } 44955d826c84SAl Viro EXPORT_SYMBOL(readlink_copy); 44961da177e4SLinus Torvalds 44971da177e4SLinus Torvalds /* 44981da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 44996b255391SAl Viro * have ->get_link() not calling nd_jump_link(). Using (or not using) it 45006b255391SAl Viro * for any given inode is up to filesystem. 45011da177e4SLinus Torvalds */ 45021da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 45031da177e4SLinus Torvalds { 4504fceef393SAl Viro DEFINE_DELAYED_CALL(done); 45055f2c4179SAl Viro struct inode *inode = d_inode(dentry); 45065f2c4179SAl Viro const char *link = inode->i_link; 4507694a1764SMarcin Slusarz int res; 4508cc314eefSLinus Torvalds 4509d4dee48bSAl Viro if (!link) { 4510fceef393SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4511680baacbSAl Viro if (IS_ERR(link)) 4512680baacbSAl Viro return PTR_ERR(link); 4513d4dee48bSAl Viro } 4514680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 4515fceef393SAl Viro do_delayed_call(&done); 4516694a1764SMarcin Slusarz return res; 45171da177e4SLinus Torvalds } 45184d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 45191da177e4SLinus Torvalds 45201da177e4SLinus Torvalds /* get the link contents into pagecache */ 45216b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4522fceef393SAl Viro struct delayed_call *callback) 45231da177e4SLinus Torvalds { 4524ebd09abbSDuane Griffin char *kaddr; 45251da177e4SLinus Torvalds struct page *page; 45266b255391SAl Viro struct address_space *mapping = inode->i_mapping; 45276b255391SAl Viro 4528d3883d4fSAl Viro if (!dentry) { 4529d3883d4fSAl Viro page = find_get_page(mapping, 0); 4530d3883d4fSAl Viro if (!page) 45316b255391SAl Viro return ERR_PTR(-ECHILD); 4532d3883d4fSAl Viro if (!PageUptodate(page)) { 4533d3883d4fSAl Viro put_page(page); 4534d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4535d3883d4fSAl Viro } 4536d3883d4fSAl Viro } else { 4537090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 45381da177e4SLinus Torvalds if (IS_ERR(page)) 45396fe6900eSNick Piggin return (char*)page; 4540d3883d4fSAl Viro } 4541fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 454221fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 454321fc61c7SAl Viro kaddr = page_address(page); 45446b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4545ebd09abbSDuane Griffin return kaddr; 45461da177e4SLinus Torvalds } 45471da177e4SLinus Torvalds 45486b255391SAl Viro EXPORT_SYMBOL(page_get_link); 45491da177e4SLinus Torvalds 4550fceef393SAl Viro void page_put_link(void *arg) 45511da177e4SLinus Torvalds { 4552fceef393SAl Viro put_page(arg); 45531da177e4SLinus Torvalds } 45544d359507SAl Viro EXPORT_SYMBOL(page_put_link); 45551da177e4SLinus Torvalds 4556aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4557aa80deabSAl Viro { 4558fceef393SAl Viro DEFINE_DELAYED_CALL(done); 45596b255391SAl Viro int res = readlink_copy(buffer, buflen, 45606b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4561fceef393SAl Viro &done)); 4562fceef393SAl Viro do_delayed_call(&done); 4563aa80deabSAl Viro return res; 4564aa80deabSAl Viro } 4565aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4566aa80deabSAl Viro 456754566b2cSNick Piggin /* 456854566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 456954566b2cSNick Piggin */ 457054566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 45711da177e4SLinus Torvalds { 45721da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 45730adb25d2SKirill Korotaev struct page *page; 4574afddba49SNick Piggin void *fsdata; 4575beb497abSDmitriy Monakhov int err; 457654566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 457754566b2cSNick Piggin if (nofs) 457854566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 45791da177e4SLinus Torvalds 45807e53cac4SNeilBrown retry: 4581afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 458254566b2cSNick Piggin flags, &page, &fsdata); 45831da177e4SLinus Torvalds if (err) 4584afddba49SNick Piggin goto fail; 4585afddba49SNick Piggin 458621fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4587afddba49SNick Piggin 4588afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4589afddba49SNick Piggin page, fsdata); 45901da177e4SLinus Torvalds if (err < 0) 45911da177e4SLinus Torvalds goto fail; 4592afddba49SNick Piggin if (err < len-1) 4593afddba49SNick Piggin goto retry; 4594afddba49SNick Piggin 45951da177e4SLinus Torvalds mark_inode_dirty(inode); 45961da177e4SLinus Torvalds return 0; 45971da177e4SLinus Torvalds fail: 45981da177e4SLinus Torvalds return err; 45991da177e4SLinus Torvalds } 46004d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 46011da177e4SLinus Torvalds 46020adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 46030adb25d2SKirill Korotaev { 46040adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4605c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 46060adb25d2SKirill Korotaev } 46074d359507SAl Viro EXPORT_SYMBOL(page_symlink); 46080adb25d2SKirill Korotaev 460992e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 46101da177e4SLinus Torvalds .readlink = generic_readlink, 46116b255391SAl Viro .get_link = page_get_link, 46121da177e4SLinus Torvalds }; 46131da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4614