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; 5028f47a016SAl Viro unsigned seq, m_seq, root_seq; 5031f55a6ecSAl Viro int last_type; 5041f55a6ecSAl Viro unsigned depth; 505756daf26SNeilBrown int total_link_count; 506697fc6caSAl Viro struct saved { 507697fc6caSAl Viro struct path link; 508697fc6caSAl Viro void *cookie; 509697fc6caSAl Viro const char *name; 510237d8b32SAl Viro struct inode *inode; 5110450b2d1SAl Viro unsigned seq; 512894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5131f55a6ecSAl Viro }; 5141f55a6ecSAl Viro 515756daf26SNeilBrown static struct nameidata *set_nameidata(struct nameidata *p) 516894bc8c4SAl Viro { 517756daf26SNeilBrown struct nameidata *old = current->nameidata; 518756daf26SNeilBrown p->stack = p->internal; 519756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 520756daf26SNeilBrown current->nameidata = p; 521756daf26SNeilBrown return old; 522894bc8c4SAl Viro } 523894bc8c4SAl Viro 524756daf26SNeilBrown static void restore_nameidata(struct nameidata *old) 525894bc8c4SAl Viro { 526756daf26SNeilBrown struct nameidata *now = current->nameidata; 527756daf26SNeilBrown 528756daf26SNeilBrown current->nameidata = old; 529756daf26SNeilBrown if (old) 530756daf26SNeilBrown old->total_link_count = now->total_link_count; 531756daf26SNeilBrown if (now->stack != now->internal) { 532756daf26SNeilBrown kfree(now->stack); 533756daf26SNeilBrown now->stack = now->internal; 534894bc8c4SAl Viro } 535894bc8c4SAl Viro } 536894bc8c4SAl Viro 537894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 538894bc8c4SAl Viro { 539bc40aee0SAl Viro struct saved *p; 540bc40aee0SAl Viro 541bc40aee0SAl Viro if (nd->flags & LOOKUP_RCU) { 542bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 543bc40aee0SAl Viro GFP_ATOMIC); 544bc40aee0SAl Viro if (unlikely(!p)) 545bc40aee0SAl Viro return -ECHILD; 546bc40aee0SAl Viro } else { 547bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 548894bc8c4SAl Viro GFP_KERNEL); 549894bc8c4SAl Viro if (unlikely(!p)) 550894bc8c4SAl Viro return -ENOMEM; 551bc40aee0SAl Viro } 552894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 553894bc8c4SAl Viro nd->stack = p; 554894bc8c4SAl Viro return 0; 555894bc8c4SAl Viro } 556894bc8c4SAl Viro 557894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 558894bc8c4SAl Viro { 559da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 560894bc8c4SAl Viro return 0; 561894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 562894bc8c4SAl Viro return 0; 563894bc8c4SAl Viro return __nd_alloc_stack(nd); 564894bc8c4SAl Viro } 565894bc8c4SAl Viro 5667973387aSAl Viro static void drop_links(struct nameidata *nd) 5677973387aSAl Viro { 5687973387aSAl Viro int i = nd->depth; 5697973387aSAl Viro while (i--) { 5707973387aSAl Viro struct saved *last = nd->stack + i; 5717973387aSAl Viro struct inode *inode = last->inode; 5727973387aSAl Viro if (last->cookie && inode->i_op->put_link) { 5737973387aSAl Viro inode->i_op->put_link(inode, last->cookie); 5747973387aSAl Viro last->cookie = NULL; 5757973387aSAl Viro } 5767973387aSAl Viro } 5777973387aSAl Viro } 5787973387aSAl Viro 5797973387aSAl Viro static void terminate_walk(struct nameidata *nd) 5807973387aSAl Viro { 5817973387aSAl Viro drop_links(nd); 5827973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 5837973387aSAl Viro int i; 5847973387aSAl Viro path_put(&nd->path); 5857973387aSAl Viro for (i = 0; i < nd->depth; i++) 5867973387aSAl Viro path_put(&nd->stack[i].link); 5877973387aSAl Viro } else { 5887973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 5897973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 5907973387aSAl Viro nd->root.mnt = NULL; 5917973387aSAl Viro rcu_read_unlock(); 5927973387aSAl Viro } 5937973387aSAl Viro nd->depth = 0; 5947973387aSAl Viro } 5957973387aSAl Viro 5967973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 5977973387aSAl Viro static bool legitimize_path(struct nameidata *nd, 5987973387aSAl Viro struct path *path, unsigned seq) 5997973387aSAl Viro { 6007973387aSAl Viro int res = __legitimize_mnt(path->mnt, nd->m_seq); 6017973387aSAl Viro if (unlikely(res)) { 6027973387aSAl Viro if (res > 0) 6037973387aSAl Viro path->mnt = NULL; 6047973387aSAl Viro path->dentry = NULL; 6057973387aSAl Viro return false; 6067973387aSAl Viro } 6077973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 6087973387aSAl Viro path->dentry = NULL; 6097973387aSAl Viro return false; 6107973387aSAl Viro } 6117973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6127973387aSAl Viro } 6137973387aSAl Viro 6147973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6157973387aSAl Viro { 6167973387aSAl Viro int i; 6177973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6187973387aSAl Viro struct saved *last = nd->stack + i; 6197973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6207973387aSAl Viro drop_links(nd); 6217973387aSAl Viro nd->depth = i + 1; 6227973387aSAl Viro return false; 6237973387aSAl Viro } 6247973387aSAl Viro } 6257973387aSAl Viro return true; 6267973387aSAl Viro } 6277973387aSAl Viro 62819660af7SAl Viro /* 62931e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 63019660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 63119660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 63219660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 63319660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 63419660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 63519660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 63619660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 63731e6b01fSNick Piggin */ 63831e6b01fSNick Piggin 63931e6b01fSNick Piggin /** 64019660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 64119660af7SAl Viro * @nd: nameidata pathwalk data 64219660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 6436e9918b7SAl Viro * @seq: seq number to check dentry against 64439191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 64531e6b01fSNick Piggin * 64619660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 64719660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 64819660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 6497973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6507973387aSAl Viro * terminate_walk(). 65131e6b01fSNick Piggin */ 6526e9918b7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry, unsigned seq) 65331e6b01fSNick Piggin { 65431e6b01fSNick Piggin struct fs_struct *fs = current->fs; 65531e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 65631e6b01fSNick Piggin 65731e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 658e5c832d5SLinus Torvalds 659e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6607973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6617973387aSAl Viro goto out2; 6627973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 6637973387aSAl Viro goto out2; 6647973387aSAl Viro if (unlikely(!lockref_get_not_dead(&parent->d_lockref))) 6657973387aSAl Viro goto out1; 66648a066e7SAl Viro 66715570086SLinus Torvalds /* 66815570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 66915570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 67015570086SLinus Torvalds * 67115570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 67215570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 67315570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 67415570086SLinus Torvalds * since we checked the sequence number of the parent after we got 67515570086SLinus Torvalds * the child sequence number. So we know the parent must still 67615570086SLinus Torvalds * be valid if the child sequence number is still valid. 67715570086SLinus Torvalds */ 67819660af7SAl Viro if (!dentry) { 679e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 680e5c832d5SLinus Torvalds goto out; 68119660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 68219660af7SAl Viro } else { 683e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 684e5c832d5SLinus Torvalds goto out; 6856e9918b7SAl Viro if (read_seqcount_retry(&dentry->d_seq, seq)) 686e5c832d5SLinus Torvalds goto drop_dentry; 68719660af7SAl Viro } 688e5c832d5SLinus Torvalds 689e5c832d5SLinus Torvalds /* 690e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 691e5c832d5SLinus Torvalds * still valid and get it if required. 692e5c832d5SLinus Torvalds */ 693e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 694e5c832d5SLinus Torvalds spin_lock(&fs->lock); 6957973387aSAl Viro if (unlikely(!path_equal(&nd->root, &fs->root))) { 6967973387aSAl Viro spin_unlock(&fs->lock); 6977973387aSAl Viro goto drop_dentry; 6987973387aSAl Viro } 69931e6b01fSNick Piggin path_get(&nd->root); 70031e6b01fSNick Piggin spin_unlock(&fs->lock); 70131e6b01fSNick Piggin } 70231e6b01fSNick Piggin 7038b61e74fSAl Viro rcu_read_unlock(); 70431e6b01fSNick Piggin return 0; 70519660af7SAl Viro 706e5c832d5SLinus Torvalds drop_dentry: 7078b61e74fSAl Viro rcu_read_unlock(); 708e5c832d5SLinus Torvalds dput(dentry); 709d0d27277SLinus Torvalds goto drop_root_mnt; 7107973387aSAl Viro out2: 7117973387aSAl Viro nd->path.mnt = NULL; 7127973387aSAl Viro out1: 7137973387aSAl Viro nd->path.dentry = NULL; 714e5c832d5SLinus Torvalds out: 7158b61e74fSAl Viro rcu_read_unlock(); 716d0d27277SLinus Torvalds drop_root_mnt: 717d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 718d0d27277SLinus Torvalds nd->root.mnt = NULL; 71931e6b01fSNick Piggin return -ECHILD; 72031e6b01fSNick Piggin } 72131e6b01fSNick Piggin 7227973387aSAl Viro static int unlazy_link(struct nameidata *nd, struct path *link, unsigned seq) 7237973387aSAl Viro { 7247973387aSAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 7257973387aSAl Viro drop_links(nd); 7267973387aSAl Viro nd->depth = 0; 7277973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 7287973387aSAl Viro nd->path.mnt = NULL; 7297973387aSAl Viro nd->path.dentry = NULL; 7307973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7317973387aSAl Viro nd->root.mnt = NULL; 7327973387aSAl Viro rcu_read_unlock(); 7337973387aSAl Viro } else if (likely(unlazy_walk(nd, NULL, 0)) == 0) { 7347973387aSAl Viro return 0; 7357973387aSAl Viro } 7367973387aSAl Viro path_put(link); 7377973387aSAl Viro return -ECHILD; 7387973387aSAl Viro } 7397973387aSAl Viro 7404ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 74134286d66SNick Piggin { 7424ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 74334286d66SNick Piggin } 74434286d66SNick Piggin 7459f1fafeeSAl Viro /** 7469f1fafeeSAl Viro * complete_walk - successful completion of path walk 7479f1fafeeSAl Viro * @nd: pointer nameidata 74839159de2SJeff Layton * 7499f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7509f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7519f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7529f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7539f1fafeeSAl Viro * need to drop nd->path. 75439159de2SJeff Layton */ 7559f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 75639159de2SJeff Layton { 75716c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 75839159de2SJeff Layton int status; 75939159de2SJeff Layton 7609f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 7619f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7629f1fafeeSAl Viro nd->root.mnt = NULL; 7636e9918b7SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 76448a066e7SAl Viro return -ECHILD; 76548a066e7SAl Viro } 7669f1fafeeSAl Viro 76716c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 76839159de2SJeff Layton return 0; 76939159de2SJeff Layton 770ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 77116c2cd71SAl Viro return 0; 77216c2cd71SAl Viro 773ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 77439159de2SJeff Layton if (status > 0) 77539159de2SJeff Layton return 0; 77639159de2SJeff Layton 77716c2cd71SAl Viro if (!status) 77839159de2SJeff Layton status = -ESTALE; 77916c2cd71SAl Viro 78039159de2SJeff Layton return status; 78139159de2SJeff Layton } 78239159de2SJeff Layton 7832a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 7842a737871SAl Viro { 785f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 7862a737871SAl Viro } 7872a737871SAl Viro 7887bd88377SAl Viro static __always_inline unsigned set_root_rcu(struct nameidata *nd) 78931e6b01fSNick Piggin { 79031e6b01fSNick Piggin struct fs_struct *fs = current->fs; 7918f47a016SAl Viro unsigned seq; 792c28cc364SNick Piggin 793c28cc364SNick Piggin do { 794c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 79531e6b01fSNick Piggin nd->root = fs->root; 7968f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 797c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 7988f47a016SAl Viro return nd->root_seq; 79931e6b01fSNick Piggin } 80031e6b01fSNick Piggin 8011d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 802051d3812SIan Kent { 803051d3812SIan Kent dput(path->dentry); 8044ac91378SJan Blunck if (path->mnt != nd->path.mnt) 805051d3812SIan Kent mntput(path->mnt); 806051d3812SIan Kent } 807051d3812SIan Kent 8087b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8097b9337aaSNick Piggin struct nameidata *nd) 810051d3812SIan Kent { 81131e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8124ac91378SJan Blunck dput(nd->path.dentry); 81331e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8144ac91378SJan Blunck mntput(nd->path.mnt); 8159a229683SHuang Shijie } 81631e6b01fSNick Piggin nd->path.mnt = path->mnt; 8174ac91378SJan Blunck nd->path.dentry = path->dentry; 818051d3812SIan Kent } 819051d3812SIan Kent 820b5fb63c1SChristoph Hellwig /* 821b5fb63c1SChristoph Hellwig * Helper to directly jump to a known parsed path from ->follow_link, 822b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 823b5fb63c1SChristoph Hellwig */ 8246e77137bSAl Viro void nd_jump_link(struct path *path) 825b5fb63c1SChristoph Hellwig { 8266e77137bSAl Viro struct nameidata *nd = current->nameidata; 827b5fb63c1SChristoph Hellwig path_put(&nd->path); 828b5fb63c1SChristoph Hellwig 829b5fb63c1SChristoph Hellwig nd->path = *path; 830b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 831b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 832b5fb63c1SChristoph Hellwig } 833b5fb63c1SChristoph Hellwig 834b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 835574197e0SAl Viro { 83621c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 837237d8b32SAl Viro struct inode *inode = last->inode; 838b9ff4429SAl Viro if (last->cookie && inode->i_op->put_link) 8395f2c4179SAl Viro inode->i_op->put_link(inode, last->cookie); 8406548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 841b9ff4429SAl Viro path_put(&last->link); 842574197e0SAl Viro } 843574197e0SAl Viro 844561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 845561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 846800179c9SKees Cook 847800179c9SKees Cook /** 848800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 84955852635SRandy Dunlap * @nd: nameidata pathwalk data 850800179c9SKees Cook * 851800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 852800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 853800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 854800179c9SKees Cook * processes from failing races against path names that may change out 855800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 856800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 857800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 858800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 859800179c9SKees Cook * 860800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 861800179c9SKees Cook */ 862fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 863800179c9SKees Cook { 864800179c9SKees Cook const struct inode *inode; 865800179c9SKees Cook const struct inode *parent; 866800179c9SKees Cook 867800179c9SKees Cook if (!sysctl_protected_symlinks) 868800179c9SKees Cook return 0; 869800179c9SKees Cook 870800179c9SKees Cook /* Allowed if owner and follower match. */ 871237d8b32SAl Viro inode = nd->stack[0].inode; 87281abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 873800179c9SKees Cook return 0; 874800179c9SKees Cook 875800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 876800179c9SKees Cook parent = nd->path.dentry->d_inode; 877800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 878800179c9SKees Cook return 0; 879800179c9SKees Cook 880800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 88181abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 882800179c9SKees Cook return 0; 883800179c9SKees Cook 88431956502SAl Viro if (nd->flags & LOOKUP_RCU) 88531956502SAl Viro return -ECHILD; 88631956502SAl Viro 8871cf2665bSAl Viro audit_log_link_denied("follow_link", &nd->stack[0].link); 888800179c9SKees Cook return -EACCES; 889800179c9SKees Cook } 890800179c9SKees Cook 891800179c9SKees Cook /** 892800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 893800179c9SKees Cook * @inode: the source inode to hardlink from 894800179c9SKees Cook * 895800179c9SKees Cook * Return false if at least one of the following conditions: 896800179c9SKees Cook * - inode is not a regular file 897800179c9SKees Cook * - inode is setuid 898800179c9SKees Cook * - inode is setgid and group-exec 899800179c9SKees Cook * - access failure for read and write 900800179c9SKees Cook * 901800179c9SKees Cook * Otherwise returns true. 902800179c9SKees Cook */ 903800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 904800179c9SKees Cook { 905800179c9SKees Cook umode_t mode = inode->i_mode; 906800179c9SKees Cook 907800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 908800179c9SKees Cook if (!S_ISREG(mode)) 909800179c9SKees Cook return false; 910800179c9SKees Cook 911800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 912800179c9SKees Cook if (mode & S_ISUID) 913800179c9SKees Cook return false; 914800179c9SKees Cook 915800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 916800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 917800179c9SKees Cook return false; 918800179c9SKees Cook 919800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 920800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 921800179c9SKees Cook return false; 922800179c9SKees Cook 923800179c9SKees Cook return true; 924800179c9SKees Cook } 925800179c9SKees Cook 926800179c9SKees Cook /** 927800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 928800179c9SKees Cook * @link: the source to hardlink from 929800179c9SKees Cook * 930800179c9SKees Cook * Block hardlink when all of: 931800179c9SKees Cook * - sysctl_protected_hardlinks enabled 932800179c9SKees Cook * - fsuid does not match inode 933800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 934800179c9SKees Cook * - not CAP_FOWNER 935800179c9SKees Cook * 936800179c9SKees Cook * Returns 0 if successful, -ve on error. 937800179c9SKees Cook */ 938800179c9SKees Cook static int may_linkat(struct path *link) 939800179c9SKees Cook { 940800179c9SKees Cook const struct cred *cred; 941800179c9SKees Cook struct inode *inode; 942800179c9SKees Cook 943800179c9SKees Cook if (!sysctl_protected_hardlinks) 944800179c9SKees Cook return 0; 945800179c9SKees Cook 946800179c9SKees Cook cred = current_cred(); 947800179c9SKees Cook inode = link->dentry->d_inode; 948800179c9SKees Cook 949800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 950800179c9SKees Cook * otherwise, it must be a safe source. 951800179c9SKees Cook */ 95281abe27bSEric W. Biederman if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || 953800179c9SKees Cook capable(CAP_FOWNER)) 954800179c9SKees Cook return 0; 955800179c9SKees Cook 956a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 957800179c9SKees Cook return -EPERM; 958800179c9SKees Cook } 959800179c9SKees Cook 9603b2e7f75SAl Viro static __always_inline 9613b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 9621da177e4SLinus Torvalds { 963ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 9641cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 965237d8b32SAl Viro struct inode *inode = last->inode; 9666d7b5aaeSAl Viro int error; 9670a959df5SAl Viro const char *res; 9681da177e4SLinus Torvalds 9698fa9dd24SNeilBrown if (!(nd->flags & LOOKUP_RCU)) { 9708fa9dd24SNeilBrown touch_atime(&last->link); 9718fa9dd24SNeilBrown cond_resched(); 9728fa9dd24SNeilBrown } else if (atime_needs_update(&last->link, inode)) { 9738fa9dd24SNeilBrown if (unlikely(unlazy_walk(nd, NULL, 0))) 9748fa9dd24SNeilBrown return ERR_PTR(-ECHILD); 9758fa9dd24SNeilBrown touch_atime(&last->link); 9768fa9dd24SNeilBrown } 9778fa9dd24SNeilBrown 978bda0be7aSNeilBrown error = security_inode_follow_link(dentry, inode, 979bda0be7aSNeilBrown nd->flags & LOOKUP_RCU); 980bda0be7aSNeilBrown if (unlikely(error)) 9816920a440SAl Viro return ERR_PTR(error); 98236f3b4f6SAl Viro 98386acdca1SAl Viro nd->last_type = LAST_BIND; 984d4dee48bSAl Viro res = inode->i_link; 985d4dee48bSAl Viro if (!res) { 9868c1b4566SAl Viro if (nd->flags & LOOKUP_RCU) { 9878c1b4566SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 9888c1b4566SAl Viro return ERR_PTR(-ECHILD); 9898c1b4566SAl Viro } 9906e77137bSAl Viro res = inode->i_op->follow_link(dentry, &last->cookie); 991fab51e8aSAl Viro if (IS_ERR_OR_NULL(res)) { 9926920a440SAl Viro last->cookie = NULL; 993fab51e8aSAl Viro return res; 9940a959df5SAl Viro } 995fab51e8aSAl Viro } 996fab51e8aSAl Viro if (*res == '/') { 9978c1b4566SAl Viro if (nd->flags & LOOKUP_RCU) { 9988f47a016SAl Viro struct dentry *d; 9998f47a016SAl Viro if (!nd->root.mnt) 10008f47a016SAl Viro set_root_rcu(nd); 10018f47a016SAl Viro nd->path = nd->root; 10028f47a016SAl Viro d = nd->path.dentry; 10038f47a016SAl Viro nd->inode = d->d_inode; 10048f47a016SAl Viro nd->seq = nd->root_seq; 10058f47a016SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 10068c1b4566SAl Viro return ERR_PTR(-ECHILD); 10078f47a016SAl Viro } else { 1008fab51e8aSAl Viro if (!nd->root.mnt) 1009fab51e8aSAl Viro set_root(nd); 1010fab51e8aSAl Viro path_put(&nd->path); 1011fab51e8aSAl Viro nd->path = nd->root; 1012fab51e8aSAl Viro path_get(&nd->root); 1013fab51e8aSAl Viro nd->inode = nd->path.dentry->d_inode; 10148f47a016SAl Viro } 1015fab51e8aSAl Viro nd->flags |= LOOKUP_JUMPED; 1016fab51e8aSAl Viro while (unlikely(*++res == '/')) 1017fab51e8aSAl Viro ; 1018fab51e8aSAl Viro } 1019fab51e8aSAl Viro if (!*res) 1020fab51e8aSAl Viro res = NULL; 10210a959df5SAl Viro return res; 10220a959df5SAl Viro } 10236d7b5aaeSAl Viro 102431e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 102531e6b01fSNick Piggin { 10260714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 10270714a533SAl Viro struct mount *parent; 102831e6b01fSNick Piggin struct dentry *mountpoint; 102931e6b01fSNick Piggin 10300714a533SAl Viro parent = mnt->mnt_parent; 10310714a533SAl Viro if (&parent->mnt == path->mnt) 103231e6b01fSNick Piggin return 0; 1033a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 103431e6b01fSNick Piggin path->dentry = mountpoint; 10350714a533SAl Viro path->mnt = &parent->mnt; 103631e6b01fSNick Piggin return 1; 103731e6b01fSNick Piggin } 103831e6b01fSNick Piggin 1039f015f126SDavid Howells /* 1040f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1041f015f126SDavid Howells * 1042f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1043f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1044f015f126SDavid Howells * Up is towards /. 1045f015f126SDavid Howells * 1046f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1047f015f126SDavid Howells * root. 1048f015f126SDavid Howells */ 1049bab77ebfSAl Viro int follow_up(struct path *path) 10501da177e4SLinus Torvalds { 10510714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 10520714a533SAl Viro struct mount *parent; 10531da177e4SLinus Torvalds struct dentry *mountpoint; 105499b7db7bSNick Piggin 105548a066e7SAl Viro read_seqlock_excl(&mount_lock); 10560714a533SAl Viro parent = mnt->mnt_parent; 10573c0a6163SAl Viro if (parent == mnt) { 105848a066e7SAl Viro read_sequnlock_excl(&mount_lock); 10591da177e4SLinus Torvalds return 0; 10601da177e4SLinus Torvalds } 10610714a533SAl Viro mntget(&parent->mnt); 1062a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 106348a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1064bab77ebfSAl Viro dput(path->dentry); 1065bab77ebfSAl Viro path->dentry = mountpoint; 1066bab77ebfSAl Viro mntput(path->mnt); 10670714a533SAl Viro path->mnt = &parent->mnt; 10681da177e4SLinus Torvalds return 1; 10691da177e4SLinus Torvalds } 10704d359507SAl Viro EXPORT_SYMBOL(follow_up); 10711da177e4SLinus Torvalds 1072b5c84bf6SNick Piggin /* 10739875cf80SDavid Howells * Perform an automount 10749875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 10759875cf80SDavid Howells * were called with. 10761da177e4SLinus Torvalds */ 1077756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 10789875cf80SDavid Howells bool *need_mntput) 107931e6b01fSNick Piggin { 10809875cf80SDavid Howells struct vfsmount *mnt; 1081ea5b778aSDavid Howells int err; 10829875cf80SDavid Howells 10839875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 10849875cf80SDavid Howells return -EREMOTE; 10859875cf80SDavid Howells 10860ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 10870ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 10880ec26fd0SMiklos Szeredi * the name. 10890ec26fd0SMiklos Szeredi * 10900ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 10915a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 10920ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 10930ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 10940ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 10950ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 10965a30d8a2SDavid Howells */ 1097756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 1098d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 10995a30d8a2SDavid Howells path->dentry->d_inode) 11009875cf80SDavid Howells return -EISDIR; 11010ec26fd0SMiklos Szeredi 1102756daf26SNeilBrown nd->total_link_count++; 1103756daf26SNeilBrown if (nd->total_link_count >= 40) 11049875cf80SDavid Howells return -ELOOP; 11059875cf80SDavid Howells 11069875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 11079875cf80SDavid Howells if (IS_ERR(mnt)) { 11089875cf80SDavid Howells /* 11099875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 11109875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 11119875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 11129875cf80SDavid Howells * 11139875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 11149875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 11159875cf80SDavid Howells * the path is inaccessible and we should say so. 11169875cf80SDavid Howells */ 1117756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 11189875cf80SDavid Howells return -EREMOTE; 11199875cf80SDavid Howells return PTR_ERR(mnt); 112031e6b01fSNick Piggin } 1121ea5b778aSDavid Howells 11229875cf80SDavid Howells if (!mnt) /* mount collision */ 11239875cf80SDavid Howells return 0; 11249875cf80SDavid Howells 11258aef1884SAl Viro if (!*need_mntput) { 11268aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 11278aef1884SAl Viro mntget(path->mnt); 11288aef1884SAl Viro *need_mntput = true; 11298aef1884SAl Viro } 113019a167afSAl Viro err = finish_automount(mnt, path); 1131ea5b778aSDavid Howells 1132ea5b778aSDavid Howells switch (err) { 1133ea5b778aSDavid Howells case -EBUSY: 1134ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 113519a167afSAl Viro return 0; 1136ea5b778aSDavid Howells case 0: 11378aef1884SAl Viro path_put(path); 11389875cf80SDavid Howells path->mnt = mnt; 11399875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 11409875cf80SDavid Howells return 0; 114119a167afSAl Viro default: 114219a167afSAl Viro return err; 11439875cf80SDavid Howells } 114419a167afSAl Viro 1145ea5b778aSDavid Howells } 11469875cf80SDavid Howells 11479875cf80SDavid Howells /* 11489875cf80SDavid Howells * Handle a dentry that is managed in some way. 1149cc53ce53SDavid Howells * - Flagged for transit management (autofs) 11509875cf80SDavid Howells * - Flagged as mountpoint 11519875cf80SDavid Howells * - Flagged as automount point 11529875cf80SDavid Howells * 11539875cf80SDavid Howells * This may only be called in refwalk mode. 11549875cf80SDavid Howells * 11559875cf80SDavid Howells * Serialization is taken care of in namespace.c 11569875cf80SDavid Howells */ 1157756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 11589875cf80SDavid Howells { 11598aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 11609875cf80SDavid Howells unsigned managed; 11619875cf80SDavid Howells bool need_mntput = false; 11628aef1884SAl Viro int ret = 0; 11639875cf80SDavid Howells 11649875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 11659875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 11669875cf80SDavid Howells * the components of that value change under us */ 11679875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 11689875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 11699875cf80SDavid Howells unlikely(managed != 0)) { 1170cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1171cc53ce53SDavid Howells * being held. */ 1172cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1173cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1174cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 11751aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1176cc53ce53SDavid Howells if (ret < 0) 11778aef1884SAl Viro break; 1178cc53ce53SDavid Howells } 1179cc53ce53SDavid Howells 11809875cf80SDavid Howells /* Transit to a mounted filesystem. */ 11819875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 11829875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 11839875cf80SDavid Howells if (mounted) { 11849875cf80SDavid Howells dput(path->dentry); 11859875cf80SDavid Howells if (need_mntput) 1186463ffb2eSAl Viro mntput(path->mnt); 1187463ffb2eSAl Viro path->mnt = mounted; 1188463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 11899875cf80SDavid Howells need_mntput = true; 11909875cf80SDavid Howells continue; 1191463ffb2eSAl Viro } 1192463ffb2eSAl Viro 11939875cf80SDavid Howells /* Something is mounted on this dentry in another 11949875cf80SDavid Howells * namespace and/or whatever was mounted there in this 119548a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 119648a066e7SAl Viro * get it */ 11971da177e4SLinus Torvalds } 11989875cf80SDavid Howells 11999875cf80SDavid Howells /* Handle an automount point */ 12009875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1201756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 12029875cf80SDavid Howells if (ret < 0) 12038aef1884SAl Viro break; 12049875cf80SDavid Howells continue; 12059875cf80SDavid Howells } 12069875cf80SDavid Howells 12079875cf80SDavid Howells /* We didn't change the current path point */ 12089875cf80SDavid Howells break; 12099875cf80SDavid Howells } 12108aef1884SAl Viro 12118aef1884SAl Viro if (need_mntput && path->mnt == mnt) 12128aef1884SAl Viro mntput(path->mnt); 12138aef1884SAl Viro if (ret == -EISDIR) 12148aef1884SAl Viro ret = 0; 12158402752eSAl Viro if (need_mntput) 12168402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 12178402752eSAl Viro if (unlikely(ret < 0)) 12188402752eSAl Viro path_put_conditional(path, nd); 12198402752eSAl Viro return ret; 12201da177e4SLinus Torvalds } 12211da177e4SLinus Torvalds 1222cc53ce53SDavid Howells int follow_down_one(struct path *path) 12231da177e4SLinus Torvalds { 12241da177e4SLinus Torvalds struct vfsmount *mounted; 12251da177e4SLinus Torvalds 12261c755af4SAl Viro mounted = lookup_mnt(path); 12271da177e4SLinus Torvalds if (mounted) { 12289393bd07SAl Viro dput(path->dentry); 12299393bd07SAl Viro mntput(path->mnt); 12309393bd07SAl Viro path->mnt = mounted; 12319393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12321da177e4SLinus Torvalds return 1; 12331da177e4SLinus Torvalds } 12341da177e4SLinus Torvalds return 0; 12351da177e4SLinus Torvalds } 12364d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12371da177e4SLinus Torvalds 1238b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 123962a7375eSIan Kent { 1240b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1241b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 124262a7375eSIan Kent } 124362a7375eSIan Kent 12449875cf80SDavid Howells /* 1245287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1246287548e4SAl Viro * we meet a managed dentry that would need blocking. 12479875cf80SDavid Howells */ 12489875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1249254cf582SAl Viro struct inode **inode, unsigned *seqp) 12509875cf80SDavid Howells { 125162a7375eSIan Kent for (;;) { 1252c7105365SAl Viro struct mount *mounted; 125362a7375eSIan Kent /* 125462a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 125562a7375eSIan Kent * that wants to block transit. 125662a7375eSIan Kent */ 1257b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1258b8faf035SNeilBrown case -ECHILD: 1259b8faf035SNeilBrown default: 1260ab90911fSDavid Howells return false; 1261b8faf035SNeilBrown case -EISDIR: 1262b8faf035SNeilBrown return true; 1263b8faf035SNeilBrown case 0: 1264b8faf035SNeilBrown break; 1265b8faf035SNeilBrown } 126662a7375eSIan Kent 126762a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1268b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 126962a7375eSIan Kent 1270474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 12719875cf80SDavid Howells if (!mounted) 12729875cf80SDavid Howells break; 1273c7105365SAl Viro path->mnt = &mounted->mnt; 1274c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1275a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1276254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 127759430262SLinus Torvalds /* 127859430262SLinus Torvalds * Update the inode too. We don't need to re-check the 127959430262SLinus Torvalds * dentry sequence number here after this d_inode read, 128059430262SLinus Torvalds * because a mount-point is always pinned. 128159430262SLinus Torvalds */ 128259430262SLinus Torvalds *inode = path->dentry->d_inode; 12839875cf80SDavid Howells } 1284f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1285b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1286287548e4SAl Viro } 1287287548e4SAl Viro 128831e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 128931e6b01fSNick Piggin { 12904023bfc9SAl Viro struct inode *inode = nd->inode; 12917bd88377SAl Viro if (!nd->root.mnt) 129231e6b01fSNick Piggin set_root_rcu(nd); 129331e6b01fSNick Piggin 129431e6b01fSNick Piggin while (1) { 129531e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 129631e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 129731e6b01fSNick Piggin break; 129831e6b01fSNick Piggin } 129931e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 130031e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 130131e6b01fSNick Piggin struct dentry *parent = old->d_parent; 130231e6b01fSNick Piggin unsigned seq; 130331e6b01fSNick Piggin 13044023bfc9SAl Viro inode = parent->d_inode; 130531e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 130631e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1307ef7562d5SAl Viro goto failed; 130831e6b01fSNick Piggin nd->path.dentry = parent; 130931e6b01fSNick Piggin nd->seq = seq; 131031e6b01fSNick Piggin break; 131131e6b01fSNick Piggin } 131231e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 131331e6b01fSNick Piggin break; 13144023bfc9SAl Viro inode = nd->path.dentry->d_inode; 131531e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 131631e6b01fSNick Piggin } 1317b37199e6SAl Viro while (d_mountpoint(nd->path.dentry)) { 1318b37199e6SAl Viro struct mount *mounted; 1319b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1320b37199e6SAl Viro if (!mounted) 1321b37199e6SAl Viro break; 1322b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1323b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 13244023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1325b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1326f5be3e29SAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1327b37199e6SAl Viro goto failed; 1328b37199e6SAl Viro } 13294023bfc9SAl Viro nd->inode = inode; 133031e6b01fSNick Piggin return 0; 1331ef7562d5SAl Viro 1332ef7562d5SAl Viro failed: 1333ef7562d5SAl Viro return -ECHILD; 133431e6b01fSNick Piggin } 133531e6b01fSNick Piggin 13369875cf80SDavid Howells /* 1337cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1338cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1339cc53ce53SDavid Howells * caller is permitted to proceed or not. 1340cc53ce53SDavid Howells */ 13417cc90cc3SAl Viro int follow_down(struct path *path) 1342cc53ce53SDavid Howells { 1343cc53ce53SDavid Howells unsigned managed; 1344cc53ce53SDavid Howells int ret; 1345cc53ce53SDavid Howells 1346cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1347cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1348cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1349cc53ce53SDavid Howells * being held. 1350cc53ce53SDavid Howells * 1351cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1352cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1353cc53ce53SDavid Howells * other than its daemon the right to mount on its 1354cc53ce53SDavid Howells * superstructure. 1355cc53ce53SDavid Howells * 1356cc53ce53SDavid Howells * The filesystem may sleep at this point. 1357cc53ce53SDavid Howells */ 1358cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1359cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1360cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1361ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 13621aed3e42SAl Viro path->dentry, false); 1363cc53ce53SDavid Howells if (ret < 0) 1364cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1365cc53ce53SDavid Howells } 1366cc53ce53SDavid Howells 1367cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1368cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1369cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1370cc53ce53SDavid Howells if (!mounted) 1371cc53ce53SDavid Howells break; 1372cc53ce53SDavid Howells dput(path->dentry); 1373cc53ce53SDavid Howells mntput(path->mnt); 1374cc53ce53SDavid Howells path->mnt = mounted; 1375cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1376cc53ce53SDavid Howells continue; 1377cc53ce53SDavid Howells } 1378cc53ce53SDavid Howells 1379cc53ce53SDavid Howells /* Don't handle automount points here */ 1380cc53ce53SDavid Howells break; 1381cc53ce53SDavid Howells } 1382cc53ce53SDavid Howells return 0; 1383cc53ce53SDavid Howells } 13844d359507SAl Viro EXPORT_SYMBOL(follow_down); 1385cc53ce53SDavid Howells 1386cc53ce53SDavid Howells /* 13879875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 13889875cf80SDavid Howells */ 13899875cf80SDavid Howells static void follow_mount(struct path *path) 13909875cf80SDavid Howells { 13919875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 13929875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 13939875cf80SDavid Howells if (!mounted) 13949875cf80SDavid Howells break; 13959875cf80SDavid Howells dput(path->dentry); 13969875cf80SDavid Howells mntput(path->mnt); 13979875cf80SDavid Howells path->mnt = mounted; 13989875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 13999875cf80SDavid Howells } 14009875cf80SDavid Howells } 14019875cf80SDavid Howells 140231e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 14031da177e4SLinus Torvalds { 14047bd88377SAl Viro if (!nd->root.mnt) 14052a737871SAl Viro set_root(nd); 1406e518ddb7SAndreas Mohr 14071da177e4SLinus Torvalds while(1) { 14084ac91378SJan Blunck struct dentry *old = nd->path.dentry; 14091da177e4SLinus Torvalds 14102a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 14112a737871SAl Viro nd->path.mnt == nd->root.mnt) { 14121da177e4SLinus Torvalds break; 14131da177e4SLinus Torvalds } 14144ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 14153088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 14163088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 14171da177e4SLinus Torvalds dput(old); 14181da177e4SLinus Torvalds break; 14191da177e4SLinus Torvalds } 14203088dd70SAl Viro if (!follow_up(&nd->path)) 14211da177e4SLinus Torvalds break; 14221da177e4SLinus Torvalds } 142379ed0226SAl Viro follow_mount(&nd->path); 142431e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 14251da177e4SLinus Torvalds } 14261da177e4SLinus Torvalds 14271da177e4SLinus Torvalds /* 1428bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1429bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1430bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1431bad61189SMiklos Szeredi * 1432bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1433baa03890SNick Piggin */ 1434bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1435201f956eSAl Viro unsigned int flags, bool *need_lookup) 1436baa03890SNick Piggin { 1437baa03890SNick Piggin struct dentry *dentry; 1438bad61189SMiklos Szeredi int error; 1439baa03890SNick Piggin 1440bad61189SMiklos Szeredi *need_lookup = false; 1441bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1442bad61189SMiklos Szeredi if (dentry) { 144339e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1444201f956eSAl Viro error = d_revalidate(dentry, flags); 1445bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1446bad61189SMiklos Szeredi if (error < 0) { 1447bad61189SMiklos Szeredi dput(dentry); 1448bad61189SMiklos Szeredi return ERR_PTR(error); 14495542aa2fSEric W. Biederman } else { 14505542aa2fSEric W. Biederman d_invalidate(dentry); 1451bad61189SMiklos Szeredi dput(dentry); 1452bad61189SMiklos Szeredi dentry = NULL; 1453bad61189SMiklos Szeredi } 1454bad61189SMiklos Szeredi } 1455bad61189SMiklos Szeredi } 1456bad61189SMiklos Szeredi } 1457baa03890SNick Piggin 1458bad61189SMiklos Szeredi if (!dentry) { 1459bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1460baa03890SNick Piggin if (unlikely(!dentry)) 1461baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1462baa03890SNick Piggin 1463bad61189SMiklos Szeredi *need_lookup = true; 1464baa03890SNick Piggin } 1465baa03890SNick Piggin return dentry; 1466baa03890SNick Piggin } 1467baa03890SNick Piggin 1468baa03890SNick Piggin /* 146913a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 147013a2c3beSJ. Bruce Fields * unhashed. 1471bad61189SMiklos Szeredi * 1472bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 147344396f4bSJosef Bacik */ 1474bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 147572bd866aSAl Viro unsigned int flags) 147644396f4bSJosef Bacik { 147744396f4bSJosef Bacik struct dentry *old; 147844396f4bSJosef Bacik 147944396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1480bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1481e188dc02SMiklos Szeredi dput(dentry); 148244396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1483e188dc02SMiklos Szeredi } 148444396f4bSJosef Bacik 148572bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 148644396f4bSJosef Bacik if (unlikely(old)) { 148744396f4bSJosef Bacik dput(dentry); 148844396f4bSJosef Bacik dentry = old; 148944396f4bSJosef Bacik } 149044396f4bSJosef Bacik return dentry; 149144396f4bSJosef Bacik } 149244396f4bSJosef Bacik 1493a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 149472bd866aSAl Viro struct dentry *base, unsigned int flags) 1495a3255546SAl Viro { 1496bad61189SMiklos Szeredi bool need_lookup; 1497a3255546SAl Viro struct dentry *dentry; 1498a3255546SAl Viro 149972bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1500bad61189SMiklos Szeredi if (!need_lookup) 1501a3255546SAl Viro return dentry; 1502bad61189SMiklos Szeredi 150372bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1504a3255546SAl Viro } 1505a3255546SAl Viro 150644396f4bSJosef Bacik /* 15071da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 15081da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 15091da177e4SLinus Torvalds * It _is_ time-critical. 15101da177e4SLinus Torvalds */ 1511e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 1512254cf582SAl Viro struct path *path, struct inode **inode, 1513254cf582SAl Viro unsigned *seqp) 15141da177e4SLinus Torvalds { 15154ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 151631e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 15175a18fff2SAl Viro int need_reval = 1; 15185a18fff2SAl Viro int status = 1; 15199875cf80SDavid Howells int err; 15209875cf80SDavid Howells 15213cac260aSAl Viro /* 1522b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1523b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1524b04f784eSNick Piggin * do the non-racy lookup, below. 1525b04f784eSNick Piggin */ 152631e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 152731e6b01fSNick Piggin unsigned seq; 1528766c4cbfSAl Viro bool negative; 1529da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15305a18fff2SAl Viro if (!dentry) 15315a18fff2SAl Viro goto unlazy; 15325a18fff2SAl Viro 153312f8ad4bSLinus Torvalds /* 153412f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 153512f8ad4bSLinus Torvalds * the dentry name information from lookup. 153612f8ad4bSLinus Torvalds */ 153763afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1538766c4cbfSAl Viro negative = d_is_negative(dentry); 153912f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 154012f8ad4bSLinus Torvalds return -ECHILD; 1541766c4cbfSAl Viro if (negative) 1542766c4cbfSAl Viro return -ENOENT; 154312f8ad4bSLinus Torvalds 154412f8ad4bSLinus Torvalds /* 154512f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 154612f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 154712f8ad4bSLinus Torvalds * 154812f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 154912f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 155012f8ad4bSLinus Torvalds */ 155131e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 155231e6b01fSNick Piggin return -ECHILD; 15535a18fff2SAl Viro 1554254cf582SAl Viro *seqp = seq; 155524643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 15564ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15575a18fff2SAl Viro if (unlikely(status <= 0)) { 15585a18fff2SAl Viro if (status != -ECHILD) 15595a18fff2SAl Viro need_reval = 0; 15605a18fff2SAl Viro goto unlazy; 15615a18fff2SAl Viro } 156224643087SAl Viro } 156331e6b01fSNick Piggin path->mnt = mnt; 156431e6b01fSNick Piggin path->dentry = dentry; 1565254cf582SAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 15669875cf80SDavid Howells return 0; 15675a18fff2SAl Viro unlazy: 1568254cf582SAl Viro if (unlazy_walk(nd, dentry, seq)) 15695a18fff2SAl Viro return -ECHILD; 15705a18fff2SAl Viro } else { 1571e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 157224643087SAl Viro } 15735a18fff2SAl Viro 157481e6f520SAl Viro if (unlikely(!dentry)) 157581e6f520SAl Viro goto need_lookup; 15765a18fff2SAl Viro 15775a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 15784ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15795a18fff2SAl Viro if (unlikely(status <= 0)) { 15805a18fff2SAl Viro if (status < 0) { 15815a18fff2SAl Viro dput(dentry); 15825a18fff2SAl Viro return status; 15835a18fff2SAl Viro } 15845542aa2fSEric W. Biederman d_invalidate(dentry); 15855a18fff2SAl Viro dput(dentry); 158681e6f520SAl Viro goto need_lookup; 15875a18fff2SAl Viro } 1588697f514dSMiklos Szeredi 1589766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1590766c4cbfSAl Viro dput(dentry); 1591766c4cbfSAl Viro return -ENOENT; 1592766c4cbfSAl Viro } 15931da177e4SLinus Torvalds path->mnt = mnt; 15941da177e4SLinus Torvalds path->dentry = dentry; 1595756daf26SNeilBrown err = follow_managed(path, nd); 15968402752eSAl Viro if (likely(!err)) 159763afdfc7SDavid Howells *inode = d_backing_inode(path->dentry); 15988402752eSAl Viro return err; 159981e6f520SAl Viro 160081e6f520SAl Viro need_lookup: 1601697f514dSMiklos Szeredi return 1; 1602697f514dSMiklos Szeredi } 1603697f514dSMiklos Szeredi 1604697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1605cc2a5271SAl Viro static int lookup_slow(struct nameidata *nd, struct path *path) 1606697f514dSMiklos Szeredi { 1607697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1608697f514dSMiklos Szeredi 1609697f514dSMiklos Szeredi parent = nd->path.dentry; 161081e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 161181e6f520SAl Viro 161281e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 1613cc2a5271SAl Viro dentry = __lookup_hash(&nd->last, parent, nd->flags); 161481e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 161581e6f520SAl Viro if (IS_ERR(dentry)) 161681e6f520SAl Viro return PTR_ERR(dentry); 1617697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1618697f514dSMiklos Szeredi path->dentry = dentry; 16198402752eSAl Viro return follow_managed(path, nd); 16201da177e4SLinus Torvalds } 16211da177e4SLinus Torvalds 162252094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 162352094c8aSAl Viro { 162452094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16254ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 162652094c8aSAl Viro if (err != -ECHILD) 162752094c8aSAl Viro return err; 16286e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 162952094c8aSAl Viro return -ECHILD; 163052094c8aSAl Viro } 16314ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 163252094c8aSAl Viro } 163352094c8aSAl Viro 16349856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 16359856fa1bSAl Viro { 16369856fa1bSAl Viro if (type == LAST_DOTDOT) { 16379856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 163870291aecSAl Viro return follow_dotdot_rcu(nd); 16399856fa1bSAl Viro } else 16409856fa1bSAl Viro follow_dotdot(nd); 16419856fa1bSAl Viro } 16429856fa1bSAl Viro return 0; 16439856fa1bSAl Viro } 16449856fa1bSAl Viro 1645181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1646181548c0SAl Viro struct inode *inode, unsigned seq) 1647d63ff28fSAl Viro { 1648626de996SAl Viro int error; 16491cf2665bSAl Viro struct saved *last; 1650756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1651626de996SAl Viro path_to_nameidata(link, nd); 1652626de996SAl Viro return -ELOOP; 1653626de996SAl Viro } 1654bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1655cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1656cd179f44SAl Viro mntget(link->mnt); 16577973387aSAl Viro } 1658626de996SAl Viro error = nd_alloc_stack(nd); 1659626de996SAl Viro if (unlikely(error)) { 1660bc40aee0SAl Viro if (error == -ECHILD) { 1661bc40aee0SAl Viro if (unlikely(unlazy_link(nd, link, seq))) 1662bc40aee0SAl Viro return -ECHILD; 1663bc40aee0SAl Viro error = nd_alloc_stack(nd); 1664bc40aee0SAl Viro } 1665bc40aee0SAl Viro if (error) { 1666cd179f44SAl Viro path_put(link); 1667626de996SAl Viro return error; 1668626de996SAl Viro } 1669bc40aee0SAl Viro } 1670626de996SAl Viro 1671ab104923SAl Viro last = nd->stack + nd->depth++; 16721cf2665bSAl Viro last->link = *link; 1673ab104923SAl Viro last->cookie = NULL; 1674181548c0SAl Viro last->inode = inode; 16750450b2d1SAl Viro last->seq = seq; 1676d63ff28fSAl Viro return 1; 1677d63ff28fSAl Viro } 1678d63ff28fSAl Viro 16793ddcd056SLinus Torvalds /* 16803ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 16813ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 16823ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 16833ddcd056SLinus Torvalds * for the common case. 16843ddcd056SLinus Torvalds */ 1685254cf582SAl Viro static inline int should_follow_link(struct nameidata *nd, struct path *link, 1686181548c0SAl Viro int follow, 1687181548c0SAl Viro struct inode *inode, unsigned seq) 16883ddcd056SLinus Torvalds { 1689d63ff28fSAl Viro if (likely(!d_is_symlink(link->dentry))) 1690d63ff28fSAl Viro return 0; 1691d63ff28fSAl Viro if (!follow) 1692d63ff28fSAl Viro return 0; 1693181548c0SAl Viro return pick_link(nd, link, inode, seq); 16943ddcd056SLinus Torvalds } 16953ddcd056SLinus Torvalds 16964693a547SAl Viro enum {WALK_GET = 1, WALK_PUT = 2}; 16974693a547SAl Viro 16984693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1699ce57dfc1SAl Viro { 1700caa85634SAl Viro struct path path; 1701ce57dfc1SAl Viro struct inode *inode; 1702254cf582SAl Viro unsigned seq; 1703ce57dfc1SAl Viro int err; 1704ce57dfc1SAl Viro /* 1705ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1706ce57dfc1SAl Viro * to be able to know about the current root directory and 1707ce57dfc1SAl Viro * parent relationships. 1708ce57dfc1SAl Viro */ 17094693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 17104693a547SAl Viro err = handle_dots(nd, nd->last_type); 17114693a547SAl Viro if (flags & WALK_PUT) 17124693a547SAl Viro put_link(nd); 17134693a547SAl Viro return err; 17144693a547SAl Viro } 1715254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1716ce57dfc1SAl Viro if (unlikely(err)) { 1717697f514dSMiklos Szeredi if (err < 0) 1718f0a9ba70SAl Viro return err; 1719697f514dSMiklos Szeredi 1720caa85634SAl Viro err = lookup_slow(nd, &path); 1721697f514dSMiklos Szeredi if (err < 0) 1722f0a9ba70SAl Viro return err; 1723697f514dSMiklos Szeredi 172463afdfc7SDavid Howells inode = d_backing_inode(path.dentry); 1725254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1726697f514dSMiklos Szeredi err = -ENOENT; 1727caa85634SAl Viro if (d_is_negative(path.dentry)) 1728697f514dSMiklos Szeredi goto out_path_put; 1729766c4cbfSAl Viro } 1730697f514dSMiklos Szeredi 17314693a547SAl Viro if (flags & WALK_PUT) 17324693a547SAl Viro put_link(nd); 1733181548c0SAl Viro err = should_follow_link(nd, &path, flags & WALK_GET, inode, seq); 1734d63ff28fSAl Viro if (unlikely(err)) 1735d63ff28fSAl Viro return err; 1736caa85634SAl Viro path_to_nameidata(&path, nd); 1737ce57dfc1SAl Viro nd->inode = inode; 1738254cf582SAl Viro nd->seq = seq; 1739ce57dfc1SAl Viro return 0; 1740697f514dSMiklos Szeredi 1741697f514dSMiklos Szeredi out_path_put: 1742caa85634SAl Viro path_to_nameidata(&path, nd); 1743697f514dSMiklos Szeredi return err; 1744ce57dfc1SAl Viro } 1745ce57dfc1SAl Viro 17461da177e4SLinus Torvalds /* 1747bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1748bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1749bfcfaa77SLinus Torvalds * 1750bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1751bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1752bfcfaa77SLinus Torvalds * fast. 1753bfcfaa77SLinus Torvalds * 1754bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1755bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1756bfcfaa77SLinus Torvalds * crossing operation. 1757bfcfaa77SLinus Torvalds * 1758bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1759bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1760bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1761bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1762bfcfaa77SLinus Torvalds */ 1763bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1764bfcfaa77SLinus Torvalds 1765f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1766bfcfaa77SLinus Torvalds 1767f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1768bfcfaa77SLinus Torvalds 1769bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1770bfcfaa77SLinus Torvalds { 177199d263d4SLinus Torvalds return hash_64(hash, 32); 1772bfcfaa77SLinus Torvalds } 1773bfcfaa77SLinus Torvalds 1774bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1775bfcfaa77SLinus Torvalds 1776bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1777bfcfaa77SLinus Torvalds 1778bfcfaa77SLinus Torvalds #endif 1779bfcfaa77SLinus Torvalds 1780bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1781bfcfaa77SLinus Torvalds { 1782bfcfaa77SLinus Torvalds unsigned long a, mask; 1783bfcfaa77SLinus Torvalds unsigned long hash = 0; 1784bfcfaa77SLinus Torvalds 1785bfcfaa77SLinus Torvalds for (;;) { 1786e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1787bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1788bfcfaa77SLinus Torvalds break; 1789bfcfaa77SLinus Torvalds hash += a; 1790f132c5beSAl Viro hash *= 9; 1791bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1792bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1793bfcfaa77SLinus Torvalds if (!len) 1794bfcfaa77SLinus Torvalds goto done; 1795bfcfaa77SLinus Torvalds } 1796a5c21dceSWill Deacon mask = bytemask_from_count(len); 1797bfcfaa77SLinus Torvalds hash += mask & a; 1798bfcfaa77SLinus Torvalds done: 1799bfcfaa77SLinus Torvalds return fold_hash(hash); 1800bfcfaa77SLinus Torvalds } 1801bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1802bfcfaa77SLinus Torvalds 1803bfcfaa77SLinus Torvalds /* 1804bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1805d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1806bfcfaa77SLinus Torvalds */ 1807d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1808bfcfaa77SLinus Torvalds { 180936126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 181036126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1811bfcfaa77SLinus Torvalds 1812bfcfaa77SLinus Torvalds hash = a = 0; 1813bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1814bfcfaa77SLinus Torvalds do { 1815bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1816bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1817e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 181836126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 181936126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1820bfcfaa77SLinus Torvalds 182136126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 182236126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 182336126f8fSLinus Torvalds 182436126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 182536126f8fSLinus Torvalds 182636126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 18279226b5b4SLinus Torvalds len += find_zero(mask); 1828d6bb3e90SLinus Torvalds return hashlen_create(fold_hash(hash), len); 1829bfcfaa77SLinus Torvalds } 1830bfcfaa77SLinus Torvalds 1831bfcfaa77SLinus Torvalds #else 1832bfcfaa77SLinus Torvalds 18330145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 18340145acc2SLinus Torvalds { 18350145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 18360145acc2SLinus Torvalds while (len--) 18370145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 18380145acc2SLinus Torvalds return end_name_hash(hash); 18390145acc2SLinus Torvalds } 1840ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 18410145acc2SLinus Torvalds 18423ddcd056SLinus Torvalds /* 1843200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1844200e9ef7SLinus Torvalds * one character. 1845200e9ef7SLinus Torvalds */ 1846d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1847200e9ef7SLinus Torvalds { 1848200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1849200e9ef7SLinus Torvalds unsigned long len = 0, c; 1850200e9ef7SLinus Torvalds 1851200e9ef7SLinus Torvalds c = (unsigned char)*name; 1852200e9ef7SLinus Torvalds do { 1853200e9ef7SLinus Torvalds len++; 1854200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1855200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1856200e9ef7SLinus Torvalds } while (c && c != '/'); 1857d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 1858200e9ef7SLinus Torvalds } 1859200e9ef7SLinus Torvalds 1860bfcfaa77SLinus Torvalds #endif 1861bfcfaa77SLinus Torvalds 1862200e9ef7SLinus Torvalds /* 18631da177e4SLinus Torvalds * Name resolution. 1864ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1865ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 18661da177e4SLinus Torvalds * 1867ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1868ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 18691da177e4SLinus Torvalds */ 18706de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 18711da177e4SLinus Torvalds { 18721da177e4SLinus Torvalds int err; 18731da177e4SLinus Torvalds 18741da177e4SLinus Torvalds while (*name=='/') 18751da177e4SLinus Torvalds name++; 18761da177e4SLinus Torvalds if (!*name) 18779e18f10aSAl Viro return 0; 18781da177e4SLinus Torvalds 18791da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 18801da177e4SLinus Torvalds for(;;) { 1881d6bb3e90SLinus Torvalds u64 hash_len; 1882fe479a58SAl Viro int type; 18831da177e4SLinus Torvalds 188452094c8aSAl Viro err = may_lookup(nd); 18851da177e4SLinus Torvalds if (err) 18863595e234SAl Viro return err; 18871da177e4SLinus Torvalds 1888d6bb3e90SLinus Torvalds hash_len = hash_name(name); 18891da177e4SLinus Torvalds 1890fe479a58SAl Viro type = LAST_NORM; 1891d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 1892fe479a58SAl Viro case 2: 1893200e9ef7SLinus Torvalds if (name[1] == '.') { 1894fe479a58SAl Viro type = LAST_DOTDOT; 189516c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 189616c2cd71SAl Viro } 1897fe479a58SAl Viro break; 1898fe479a58SAl Viro case 1: 1899fe479a58SAl Viro type = LAST_DOT; 1900fe479a58SAl Viro } 19015a202bcdSAl Viro if (likely(type == LAST_NORM)) { 19025a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 190316c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 19045a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 1905a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 1906da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 19075a202bcdSAl Viro if (err < 0) 19083595e234SAl Viro return err; 1909d6bb3e90SLinus Torvalds hash_len = this.hash_len; 1910d6bb3e90SLinus Torvalds name = this.name; 19115a202bcdSAl Viro } 19125a202bcdSAl Viro } 1913fe479a58SAl Viro 1914d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 1915d6bb3e90SLinus Torvalds nd->last.name = name; 19165f4a6a69SAl Viro nd->last_type = type; 19175f4a6a69SAl Viro 1918d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 1919d6bb3e90SLinus Torvalds if (!*name) 1920bdf6cbf1SAl Viro goto OK; 1921200e9ef7SLinus Torvalds /* 1922200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1923200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1924200e9ef7SLinus Torvalds */ 1925200e9ef7SLinus Torvalds do { 1926d6bb3e90SLinus Torvalds name++; 1927d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 19288620c238SAl Viro if (unlikely(!*name)) { 19298620c238SAl Viro OK: 1930368ee9baSAl Viro /* pathname body, done */ 19318620c238SAl Viro if (!nd->depth) 19328620c238SAl Viro return 0; 19338620c238SAl Viro name = nd->stack[nd->depth - 1].name; 1934368ee9baSAl Viro /* trailing symlink, done */ 19358620c238SAl Viro if (!name) 19368620c238SAl Viro return 0; 19378620c238SAl Viro /* last component of nested symlink */ 19384693a547SAl Viro err = walk_component(nd, WALK_GET | WALK_PUT); 19398620c238SAl Viro } else { 19404693a547SAl Viro err = walk_component(nd, WALK_GET); 19418620c238SAl Viro } 1942ce57dfc1SAl Viro if (err < 0) 19433595e234SAl Viro return err; 1944fe479a58SAl Viro 1945ce57dfc1SAl Viro if (err) { 1946626de996SAl Viro const char *s = get_link(nd); 19475a460275SAl Viro 19483595e234SAl Viro if (unlikely(IS_ERR(s))) 19493595e234SAl Viro return PTR_ERR(s); 1950172a39a0SAl Viro err = 0; 195112b09578SAl Viro if (unlikely(!s)) { 195212b09578SAl Viro /* jumped */ 1953b9ff4429SAl Viro put_link(nd); 195412b09578SAl Viro } else { 1955071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 195632cd7468SAl Viro name = s; 19579e18f10aSAl Viro continue; 195848c8b0c5SAl Viro } 195931e6b01fSNick Piggin } 19603595e234SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) 19613595e234SAl Viro return -ENOTDIR; 19625f4a6a69SAl Viro } 1963ce57dfc1SAl Viro } 19641da177e4SLinus Torvalds 1965368ee9baSAl Viro static const char *path_init(int dfd, const struct filename *name, 1966368ee9baSAl Viro unsigned int flags, struct nameidata *nd) 196731e6b01fSNick Piggin { 196831e6b01fSNick Piggin int retval = 0; 1969fd2f7cb5SAl Viro const char *s = name->name; 197031e6b01fSNick Piggin 197131e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 1972980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 197331e6b01fSNick Piggin nd->depth = 0; 1974368ee9baSAl Viro nd->total_link_count = 0; 19755b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 1976b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 1977b18825a7SDavid Howells struct inode *inode = root->d_inode; 1978fd2f7cb5SAl Viro if (*s) { 197944b1d530SMiklos Szeredi if (!d_can_lookup(root)) 1980368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 19815b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 19825b6ca027SAl Viro if (retval) 1983368ee9baSAl Viro return ERR_PTR(retval); 198473d049a4SAl Viro } 19855b6ca027SAl Viro nd->path = nd->root; 19865b6ca027SAl Viro nd->inode = inode; 19875b6ca027SAl Viro if (flags & LOOKUP_RCU) { 19888b61e74fSAl Viro rcu_read_lock(); 19895b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 19908f47a016SAl Viro nd->root_seq = nd->seq; 199148a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 19925b6ca027SAl Viro } else { 19935b6ca027SAl Viro path_get(&nd->path); 19945b6ca027SAl Viro } 1995368ee9baSAl Viro return s; 19965b6ca027SAl Viro } 19975b6ca027SAl Viro 199831e6b01fSNick Piggin nd->root.mnt = NULL; 199931e6b01fSNick Piggin 200048a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 2001fd2f7cb5SAl Viro if (*s == '/') { 2002e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 20038b61e74fSAl Viro rcu_read_lock(); 20047bd88377SAl Viro nd->seq = set_root_rcu(nd); 2005e41f7d4eSAl Viro } else { 2006e41f7d4eSAl Viro set_root(nd); 2007e41f7d4eSAl Viro path_get(&nd->root); 2008e41f7d4eSAl Viro } 200931e6b01fSNick Piggin nd->path = nd->root; 201031e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 2011e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 201231e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2013c28cc364SNick Piggin unsigned seq; 201431e6b01fSNick Piggin 20158b61e74fSAl Viro rcu_read_lock(); 201631e6b01fSNick Piggin 2017c28cc364SNick Piggin do { 2018c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 201931e6b01fSNick Piggin nd->path = fs->pwd; 2020c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2021c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2022e41f7d4eSAl Viro } else { 2023e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2024e41f7d4eSAl Viro } 202531e6b01fSNick Piggin } else { 2026582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 20272903ff01SAl Viro struct fd f = fdget_raw(dfd); 202831e6b01fSNick Piggin struct dentry *dentry; 202931e6b01fSNick Piggin 20302903ff01SAl Viro if (!f.file) 2031368ee9baSAl Viro return ERR_PTR(-EBADF); 203231e6b01fSNick Piggin 20332903ff01SAl Viro dentry = f.file->f_path.dentry; 203431e6b01fSNick Piggin 2035fd2f7cb5SAl Viro if (*s) { 203644b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 20372903ff01SAl Viro fdput(f); 2038368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2039f52e0c11SAl Viro } 20402903ff01SAl Viro } 20412903ff01SAl Viro 20422903ff01SAl Viro nd->path = f.file->f_path; 2043e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 20448b61e74fSAl Viro rcu_read_lock(); 204534a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 204634a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 20475590ff0dSUlrich Drepper } else { 20482903ff01SAl Viro path_get(&nd->path); 204934a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 20501da177e4SLinus Torvalds } 205134a26b99SAl Viro fdput(f); 2052368ee9baSAl Viro return s; 2053e41f7d4eSAl Viro } 2054e41f7d4eSAl Viro 205531e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 20564023bfc9SAl Viro if (!(flags & LOOKUP_RCU)) 2057368ee9baSAl Viro return s; 20584023bfc9SAl Viro if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) 2059368ee9baSAl Viro return s; 20604023bfc9SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 20614023bfc9SAl Viro nd->root.mnt = NULL; 20624023bfc9SAl Viro rcu_read_unlock(); 2063368ee9baSAl Viro return ERR_PTR(-ECHILD); 20649b4a9b14SAl Viro } 20659b4a9b14SAl Viro 2066893b7775SAl Viro static void path_cleanup(struct nameidata *nd) 2067893b7775SAl Viro { 2068893b7775SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 2069893b7775SAl Viro path_put(&nd->root); 2070893b7775SAl Viro nd->root.mnt = NULL; 2071893b7775SAl Viro } 20729b4a9b14SAl Viro } 20739b4a9b14SAl Viro 20743bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 207595fa25d9SAl Viro { 207695fa25d9SAl Viro const char *s; 2077fec2fa24SAl Viro int error = may_follow_link(nd); 2078deb106c6SAl Viro if (unlikely(error)) 20793bdba28bSAl Viro return ERR_PTR(error); 208095fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2081fab51e8aSAl Viro nd->stack[0].name = NULL; 20823b2e7f75SAl Viro s = get_link(nd); 2083deb106c6SAl Viro return s ? s : ""; 208495fa25d9SAl Viro } 208595fa25d9SAl Viro 2086caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2087bd92d7feSAl Viro { 2088bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2089bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2090bd92d7feSAl Viro 2091bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 2092deb106c6SAl Viro return walk_component(nd, 20934693a547SAl Viro nd->flags & LOOKUP_FOLLOW 20944693a547SAl Viro ? nd->depth 20954693a547SAl Viro ? WALK_PUT | WALK_GET 20964693a547SAl Viro : WALK_GET 20974693a547SAl Viro : 0); 2098bd92d7feSAl Viro } 2099bd92d7feSAl Viro 21009b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 21015eb6b495SAl Viro static int path_lookupat(int dfd, const struct filename *name, 21029b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 21039b4a9b14SAl Viro { 2104368ee9baSAl Viro const char *s = path_init(dfd, name, flags, nd); 2105bd92d7feSAl Viro int err; 210631e6b01fSNick Piggin 2107368ee9baSAl Viro if (IS_ERR(s)) 2108368ee9baSAl Viro return PTR_ERR(s); 21093bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 21103bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 21113bdba28bSAl Viro s = trailing_symlink(nd); 21123bdba28bSAl Viro if (IS_ERR(s)) { 21133bdba28bSAl Viro err = PTR_ERR(s); 21146d7b5aaeSAl Viro break; 2115bd92d7feSAl Viro } 2116bd92d7feSAl Viro } 21179f1fafeeSAl Viro if (!err) 21189f1fafeeSAl Viro err = complete_walk(nd); 2119bd92d7feSAl Viro 2120deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2121deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2122bd23a539SAl Viro err = -ENOTDIR; 2123deb106c6SAl Viro if (err) 2124deb106c6SAl Viro terminate_walk(nd); 212516c2cd71SAl Viro 2126893b7775SAl Viro path_cleanup(nd); 2127bd92d7feSAl Viro return err; 212831e6b01fSNick Piggin } 212931e6b01fSNick Piggin 2130873f1eedSJeff Layton static int filename_lookup(int dfd, struct filename *name, 2131873f1eedSJeff Layton unsigned int flags, struct nameidata *nd) 2132873f1eedSJeff Layton { 2133894bc8c4SAl Viro int retval; 2134756daf26SNeilBrown struct nameidata *saved_nd = set_nameidata(nd); 2135894bc8c4SAl Viro 2136894bc8c4SAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 2137873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 21385eb6b495SAl Viro retval = path_lookupat(dfd, name, flags, nd); 2139873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 21405eb6b495SAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 2141873f1eedSJeff Layton 2142873f1eedSJeff Layton if (likely(!retval)) 2143adb5c247SJeff Layton audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); 2144756daf26SNeilBrown restore_nameidata(saved_nd); 2145873f1eedSJeff Layton return retval; 2146873f1eedSJeff Layton } 2147873f1eedSJeff Layton 21488bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 21498bcb77faSAl Viro static int path_parentat(int dfd, const struct filename *name, 21508bcb77faSAl Viro unsigned int flags, struct nameidata *nd) 21518bcb77faSAl Viro { 2152368ee9baSAl Viro const char *s = path_init(dfd, name, flags, nd); 2153368ee9baSAl Viro int err; 2154368ee9baSAl Viro if (IS_ERR(s)) 2155368ee9baSAl Viro return PTR_ERR(s); 2156368ee9baSAl Viro err = link_path_walk(s, nd); 21578bcb77faSAl Viro if (!err) 21588bcb77faSAl Viro err = complete_walk(nd); 2159deb106c6SAl Viro if (err) 2160deb106c6SAl Viro terminate_walk(nd); 21618bcb77faSAl Viro path_cleanup(nd); 21628bcb77faSAl Viro return err; 21638bcb77faSAl Viro } 21648bcb77faSAl Viro 21658bcb77faSAl Viro static int filename_parentat(int dfd, struct filename *name, 21668bcb77faSAl Viro unsigned int flags, struct nameidata *nd) 21678bcb77faSAl Viro { 21688bcb77faSAl Viro int retval; 21698bcb77faSAl Viro struct nameidata *saved_nd = set_nameidata(nd); 21708bcb77faSAl Viro 21718bcb77faSAl Viro retval = path_parentat(dfd, name, flags | LOOKUP_RCU, nd); 21728bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 21738bcb77faSAl Viro retval = path_parentat(dfd, name, flags, nd); 21748bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 21758bcb77faSAl Viro retval = path_parentat(dfd, name, flags | LOOKUP_REVAL, nd); 21768bcb77faSAl Viro 21778bcb77faSAl Viro if (likely(!retval)) 21788bcb77faSAl Viro audit_inode(name, nd->path.dentry, LOOKUP_PARENT); 21798bcb77faSAl Viro restore_nameidata(saved_nd); 21808bcb77faSAl Viro return retval; 21818bcb77faSAl Viro } 21828bcb77faSAl Viro 218379714f72SAl Viro /* does lookup, returns the object with parent locked */ 218479714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 21855590ff0dSUlrich Drepper { 218651689104SPaul Moore struct filename *filename = getname_kernel(name); 218779714f72SAl Viro struct nameidata nd; 218879714f72SAl Viro struct dentry *d; 218951689104SPaul Moore int err; 219051689104SPaul Moore 219151689104SPaul Moore if (IS_ERR(filename)) 219251689104SPaul Moore return ERR_CAST(filename); 219351689104SPaul Moore 21948bcb77faSAl Viro err = filename_parentat(AT_FDCWD, filename, 0, &nd); 219551689104SPaul Moore if (err) { 219651689104SPaul Moore d = ERR_PTR(err); 219751689104SPaul Moore goto out; 219851689104SPaul Moore } 219979714f72SAl Viro if (nd.last_type != LAST_NORM) { 220079714f72SAl Viro path_put(&nd.path); 220151689104SPaul Moore d = ERR_PTR(-EINVAL); 220251689104SPaul Moore goto out; 220379714f72SAl Viro } 220479714f72SAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 22051e0ea001SAl Viro d = __lookup_hash(&nd.last, nd.path.dentry, 0); 220679714f72SAl Viro if (IS_ERR(d)) { 220779714f72SAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 220879714f72SAl Viro path_put(&nd.path); 220951689104SPaul Moore goto out; 221079714f72SAl Viro } 221179714f72SAl Viro *path = nd.path; 221251689104SPaul Moore out: 221351689104SPaul Moore putname(filename); 221479714f72SAl Viro return d; 22155590ff0dSUlrich Drepper } 22165590ff0dSUlrich Drepper 2217d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2218d1811465SAl Viro { 2219d1811465SAl Viro struct nameidata nd; 222074eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 222174eb8cc5SAl Viro int res = PTR_ERR(filename); 222274eb8cc5SAl Viro 222374eb8cc5SAl Viro if (!IS_ERR(filename)) { 222474eb8cc5SAl Viro res = filename_lookup(AT_FDCWD, filename, flags, &nd); 222574eb8cc5SAl Viro putname(filename); 2226d1811465SAl Viro if (!res) 2227d1811465SAl Viro *path = nd.path; 222874eb8cc5SAl Viro } 2229d1811465SAl Viro return res; 2230d1811465SAl Viro } 22314d359507SAl Viro EXPORT_SYMBOL(kern_path); 2232d1811465SAl Viro 223316f18200SJosef 'Jeff' Sipek /** 223416f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 223516f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 223616f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 223716f18200SJosef 'Jeff' Sipek * @name: pointer to file name 223816f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2239e0a01249SAl Viro * @path: pointer to struct path to fill 224016f18200SJosef 'Jeff' Sipek */ 224116f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 224216f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2243e0a01249SAl Viro struct path *path) 224416f18200SJosef 'Jeff' Sipek { 224574eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 224674eb8cc5SAl Viro int err = PTR_ERR(filename); 224774eb8cc5SAl Viro 224874eb8cc5SAl Viro BUG_ON(flags & LOOKUP_PARENT); 224974eb8cc5SAl Viro 225074eb8cc5SAl Viro /* the first argument of filename_lookup() is ignored with LOOKUP_ROOT */ 225174eb8cc5SAl Viro if (!IS_ERR(filename)) { 2252e0a01249SAl Viro struct nameidata nd; 2253e0a01249SAl Viro nd.root.dentry = dentry; 2254e0a01249SAl Viro nd.root.mnt = mnt; 225574eb8cc5SAl Viro err = filename_lookup(AT_FDCWD, filename, 225674eb8cc5SAl Viro flags | LOOKUP_ROOT, &nd); 2257e0a01249SAl Viro if (!err) 2258e0a01249SAl Viro *path = nd.path; 225974eb8cc5SAl Viro putname(filename); 226074eb8cc5SAl Viro } 2261e0a01249SAl Viro return err; 226216f18200SJosef 'Jeff' Sipek } 22634d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 226416f18200SJosef 'Jeff' Sipek 2265eead1911SChristoph Hellwig /** 2266a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2267eead1911SChristoph Hellwig * @name: pathname component to lookup 2268eead1911SChristoph Hellwig * @base: base directory to lookup from 2269eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2270eead1911SChristoph Hellwig * 2271a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 22729e7543e9SAl Viro * not be called by generic code. 2273eead1911SChristoph Hellwig */ 2274057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2275057f6c01SJames Morris { 2276057f6c01SJames Morris struct qstr this; 22776a96ba54SAl Viro unsigned int c; 2278cda309deSMiklos Szeredi int err; 2279057f6c01SJames Morris 22802f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 22812f9092e1SDavid Woodhouse 22826a96ba54SAl Viro this.name = name; 22836a96ba54SAl Viro this.len = len; 22840145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 22856a96ba54SAl Viro if (!len) 22866a96ba54SAl Viro return ERR_PTR(-EACCES); 22876a96ba54SAl Viro 228821d8a15aSAl Viro if (unlikely(name[0] == '.')) { 228921d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 229021d8a15aSAl Viro return ERR_PTR(-EACCES); 229121d8a15aSAl Viro } 229221d8a15aSAl Viro 22936a96ba54SAl Viro while (len--) { 22946a96ba54SAl Viro c = *(const unsigned char *)name++; 22956a96ba54SAl Viro if (c == '/' || c == '\0') 22966a96ba54SAl Viro return ERR_PTR(-EACCES); 22976a96ba54SAl Viro } 22985a202bcdSAl Viro /* 22995a202bcdSAl Viro * See if the low-level filesystem might want 23005a202bcdSAl Viro * to use its own hash.. 23015a202bcdSAl Viro */ 23025a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2303da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 23045a202bcdSAl Viro if (err < 0) 23055a202bcdSAl Viro return ERR_PTR(err); 23065a202bcdSAl Viro } 2307eead1911SChristoph Hellwig 2308cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2309cda309deSMiklos Szeredi if (err) 2310cda309deSMiklos Szeredi return ERR_PTR(err); 2311cda309deSMiklos Szeredi 231272bd866aSAl Viro return __lookup_hash(&this, base, 0); 2313057f6c01SJames Morris } 23144d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2315057f6c01SJames Morris 23161fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 23171fa1e7f6SAndy Whitcroft struct path *path, int *empty) 23181da177e4SLinus Torvalds { 23192d8f3038SAl Viro struct nameidata nd; 232091a27b2aSJeff Layton struct filename *tmp = getname_flags(name, flags, empty); 23211da177e4SLinus Torvalds int err = PTR_ERR(tmp); 23221da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 23232d8f3038SAl Viro 23242d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 23252d8f3038SAl Viro 2326873f1eedSJeff Layton err = filename_lookup(dfd, tmp, flags, &nd); 23271da177e4SLinus Torvalds putname(tmp); 23282d8f3038SAl Viro if (!err) 23292d8f3038SAl Viro *path = nd.path; 23301da177e4SLinus Torvalds } 23311da177e4SLinus Torvalds return err; 23321da177e4SLinus Torvalds } 23331da177e4SLinus Torvalds 23341fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 23351fa1e7f6SAndy Whitcroft struct path *path) 23361fa1e7f6SAndy Whitcroft { 2337f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 23381fa1e7f6SAndy Whitcroft } 23394d359507SAl Viro EXPORT_SYMBOL(user_path_at); 23401fa1e7f6SAndy Whitcroft 2341873f1eedSJeff Layton /* 2342873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2343873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2344873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2345873f1eedSJeff Layton * path-walking is complete. 2346873f1eedSJeff Layton */ 234791a27b2aSJeff Layton static struct filename * 2348f5beed75SAl Viro user_path_parent(int dfd, const char __user *path, 2349f5beed75SAl Viro struct path *parent, 2350f5beed75SAl Viro struct qstr *last, 2351f5beed75SAl Viro int *type, 23529e790bd6SJeff Layton unsigned int flags) 23532ad94ae6SAl Viro { 2354f5beed75SAl Viro struct nameidata nd; 235591a27b2aSJeff Layton struct filename *s = getname(path); 23562ad94ae6SAl Viro int error; 23572ad94ae6SAl Viro 23589e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 23599e790bd6SJeff Layton flags &= LOOKUP_REVAL; 23609e790bd6SJeff Layton 23612ad94ae6SAl Viro if (IS_ERR(s)) 236291a27b2aSJeff Layton return s; 23632ad94ae6SAl Viro 23648bcb77faSAl Viro error = filename_parentat(dfd, s, flags, &nd); 236591a27b2aSJeff Layton if (error) { 23662ad94ae6SAl Viro putname(s); 236791a27b2aSJeff Layton return ERR_PTR(error); 236891a27b2aSJeff Layton } 2369f5beed75SAl Viro *parent = nd.path; 2370f5beed75SAl Viro *last = nd.last; 2371f5beed75SAl Viro *type = nd.last_type; 23722ad94ae6SAl Viro 237391a27b2aSJeff Layton return s; 23742ad94ae6SAl Viro } 23752ad94ae6SAl Viro 23768033426eSJeff Layton /** 2377197df04cSAl Viro * mountpoint_last - look up last component for umount 23788033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 23798033426eSJeff Layton * @path: pointer to container for result 23808033426eSJeff Layton * 23818033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 23828033426eSJeff Layton * need to resolve the path without doing any revalidation. 23838033426eSJeff Layton * 23848033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 23858033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 23868033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 23878033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 23888033426eSJeff Layton * bogus and it doesn't exist. 23898033426eSJeff Layton * 23908033426eSJeff Layton * Returns: 23918033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 23928033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 23938033426eSJeff Layton * put in this case. 23948033426eSJeff Layton * 23958033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 23968033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 23978033426eSJeff Layton * The nd->path reference will also be put. 23988033426eSJeff Layton * 23998033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 24008033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 24018033426eSJeff Layton * to the link, and nd->path will *not* be put. 24028033426eSJeff Layton */ 24038033426eSJeff Layton static int 2404197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 24058033426eSJeff Layton { 24068033426eSJeff Layton int error = 0; 24078033426eSJeff Layton struct dentry *dentry; 24088033426eSJeff Layton struct dentry *dir = nd->path.dentry; 24098033426eSJeff Layton 241035759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 241135759521SAl Viro if (nd->flags & LOOKUP_RCU) { 24126e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 2413deb106c6SAl Viro return -ECHILD; 24148033426eSJeff Layton } 24158033426eSJeff Layton 24168033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 24178033426eSJeff Layton 24188033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 24198033426eSJeff Layton error = handle_dots(nd, nd->last_type); 242035759521SAl Viro if (error) 2421deb106c6SAl Viro return error; 24228033426eSJeff Layton dentry = dget(nd->path.dentry); 242335759521SAl Viro goto done; 24248033426eSJeff Layton } 24258033426eSJeff Layton 24268033426eSJeff Layton mutex_lock(&dir->d_inode->i_mutex); 24278033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 24288033426eSJeff Layton if (!dentry) { 24298033426eSJeff Layton /* 24308033426eSJeff Layton * No cached dentry. Mounted dentries are pinned in the cache, 24318033426eSJeff Layton * so that means that this dentry is probably a symlink or the 24328033426eSJeff Layton * path doesn't actually point to a mounted dentry. 24338033426eSJeff Layton */ 24348033426eSJeff Layton dentry = d_alloc(dir, &nd->last); 24358033426eSJeff Layton if (!dentry) { 2436bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 2437deb106c6SAl Viro return -ENOMEM; 24388033426eSJeff Layton } 243935759521SAl Viro dentry = lookup_real(dir->d_inode, dentry, nd->flags); 2440bcceeebaSDave Jones if (IS_ERR(dentry)) { 2441bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 2442deb106c6SAl Viro return PTR_ERR(dentry); 24438033426eSJeff Layton } 2444bcceeebaSDave Jones } 24458033426eSJeff Layton mutex_unlock(&dir->d_inode->i_mutex); 24468033426eSJeff Layton 244735759521SAl Viro done: 2448698934dfSDavid Howells if (d_is_negative(dentry)) { 24498033426eSJeff Layton dput(dentry); 2450deb106c6SAl Viro return -ENOENT; 245135759521SAl Viro } 2452191d7f73SAl Viro if (nd->depth) 2453191d7f73SAl Viro put_link(nd); 24548033426eSJeff Layton path->dentry = dentry; 2455295dc39dSVasily Averin path->mnt = nd->path.mnt; 2456181548c0SAl Viro error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW, 2457181548c0SAl Viro d_backing_inode(dentry), 0); 2458deb106c6SAl Viro if (unlikely(error)) 2459d63ff28fSAl Viro return error; 2460295dc39dSVasily Averin mntget(path->mnt); 24618033426eSJeff Layton follow_mount(path); 2462deb106c6SAl Viro return 0; 24638033426eSJeff Layton } 24648033426eSJeff Layton 24658033426eSJeff Layton /** 2466197df04cSAl Viro * path_mountpoint - look up a path to be umounted 24678033426eSJeff Layton * @dfd: directory file descriptor to start walk from 24688033426eSJeff Layton * @name: full pathname to walk 2469606d6fe3SRandy Dunlap * @path: pointer to container for result 24708033426eSJeff Layton * @flags: lookup flags 24718033426eSJeff Layton * 24728033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2473606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 24748033426eSJeff Layton */ 24758033426eSJeff Layton static int 2476668696dcSAl Viro path_mountpoint(int dfd, const struct filename *name, struct path *path, 247746afd6f6SAl Viro struct nameidata *nd, unsigned int flags) 24788033426eSJeff Layton { 2479368ee9baSAl Viro const char *s = path_init(dfd, name, flags, nd); 2480368ee9baSAl Viro int err; 2481368ee9baSAl Viro if (IS_ERR(s)) 2482368ee9baSAl Viro return PTR_ERR(s); 24833bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 24843bdba28bSAl Viro (err = mountpoint_last(nd, path)) > 0) { 24853bdba28bSAl Viro s = trailing_symlink(nd); 24863bdba28bSAl Viro if (IS_ERR(s)) { 24873bdba28bSAl Viro err = PTR_ERR(s); 24888033426eSJeff Layton break; 24898033426eSJeff Layton } 24903bdba28bSAl Viro } 2491deb106c6SAl Viro terminate_walk(nd); 249246afd6f6SAl Viro path_cleanup(nd); 24938033426eSJeff Layton return err; 24948033426eSJeff Layton } 24958033426eSJeff Layton 24962d864651SAl Viro static int 2497668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 24982d864651SAl Viro unsigned int flags) 24992d864651SAl Viro { 2500756daf26SNeilBrown struct nameidata nd, *saved; 2501cbaab2dbSAl Viro int error; 2502668696dcSAl Viro if (IS_ERR(name)) 2503668696dcSAl Viro return PTR_ERR(name); 2504756daf26SNeilBrown saved = set_nameidata(&nd); 250546afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_RCU); 25062d864651SAl Viro if (unlikely(error == -ECHILD)) 250746afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags); 25082d864651SAl Viro if (unlikely(error == -ESTALE)) 250946afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_REVAL); 25102d864651SAl Viro if (likely(!error)) 2511668696dcSAl Viro audit_inode(name, path->dentry, 0); 2512756daf26SNeilBrown restore_nameidata(saved); 2513668696dcSAl Viro putname(name); 25142d864651SAl Viro return error; 25152d864651SAl Viro } 25162d864651SAl Viro 25178033426eSJeff Layton /** 2518197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 25198033426eSJeff Layton * @dfd: directory file descriptor 25208033426eSJeff Layton * @name: pathname from userland 25218033426eSJeff Layton * @flags: lookup flags 25228033426eSJeff Layton * @path: pointer to container to hold result 25238033426eSJeff Layton * 25248033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 25258033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 25268033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 25278033426eSJeff Layton * and avoid revalidating the last component. 25288033426eSJeff Layton * 25298033426eSJeff Layton * Returns 0 and populates "path" on success. 25308033426eSJeff Layton */ 25318033426eSJeff Layton int 2532197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 25338033426eSJeff Layton struct path *path) 25348033426eSJeff Layton { 2535cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 25368033426eSJeff Layton } 25378033426eSJeff Layton 25382d864651SAl Viro int 25392d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 25402d864651SAl Viro unsigned int flags) 25412d864651SAl Viro { 2542cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 25432d864651SAl Viro } 25442d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 25452d864651SAl Viro 2546cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 25471da177e4SLinus Torvalds { 25488e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2549da9592edSDavid Howells 25508e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 25511da177e4SLinus Torvalds return 0; 25528e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 25531da177e4SLinus Torvalds return 0; 255423adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 25551da177e4SLinus Torvalds } 2556cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 25571da177e4SLinus Torvalds 25581da177e4SLinus Torvalds /* 25591da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 25601da177e4SLinus Torvalds * whether the type of victim is right. 25611da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 25621da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 25631da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 25641da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 25651da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 25661da177e4SLinus Torvalds * a. be owner of dir, or 25671da177e4SLinus Torvalds * b. be owner of victim, or 25681da177e4SLinus Torvalds * c. have CAP_FOWNER capability 25691da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 25701da177e4SLinus Torvalds * links pointing to it. 25711da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 25721da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 25731da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 25741da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 25751da177e4SLinus Torvalds * nfs_async_unlink(). 25761da177e4SLinus Torvalds */ 2577b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 25781da177e4SLinus Torvalds { 257963afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 25801da177e4SLinus Torvalds int error; 25811da177e4SLinus Torvalds 2582b18825a7SDavid Howells if (d_is_negative(victim)) 25831da177e4SLinus Torvalds return -ENOENT; 2584b18825a7SDavid Howells BUG_ON(!inode); 25851da177e4SLinus Torvalds 25861da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 25874fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 25881da177e4SLinus Torvalds 2589f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 25901da177e4SLinus Torvalds if (error) 25911da177e4SLinus Torvalds return error; 25921da177e4SLinus Torvalds if (IS_APPEND(dir)) 25931da177e4SLinus Torvalds return -EPERM; 2594b18825a7SDavid Howells 2595b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2596b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 25971da177e4SLinus Torvalds return -EPERM; 25981da177e4SLinus Torvalds if (isdir) { 259944b1d530SMiklos Szeredi if (!d_is_dir(victim)) 26001da177e4SLinus Torvalds return -ENOTDIR; 26011da177e4SLinus Torvalds if (IS_ROOT(victim)) 26021da177e4SLinus Torvalds return -EBUSY; 260344b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 26041da177e4SLinus Torvalds return -EISDIR; 26051da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 26061da177e4SLinus Torvalds return -ENOENT; 26071da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 26081da177e4SLinus Torvalds return -EBUSY; 26091da177e4SLinus Torvalds return 0; 26101da177e4SLinus Torvalds } 26111da177e4SLinus Torvalds 26121da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 26131da177e4SLinus Torvalds * dir. 26141da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 26151da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 26161da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 26171da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 26181da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 26191da177e4SLinus Torvalds */ 2620a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 26211da177e4SLinus Torvalds { 262214e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 26231da177e4SLinus Torvalds if (child->d_inode) 26241da177e4SLinus Torvalds return -EEXIST; 26251da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 26261da177e4SLinus Torvalds return -ENOENT; 2627f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 26281da177e4SLinus Torvalds } 26291da177e4SLinus Torvalds 26301da177e4SLinus Torvalds /* 26311da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 26321da177e4SLinus Torvalds */ 26331da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 26341da177e4SLinus Torvalds { 26351da177e4SLinus Torvalds struct dentry *p; 26361da177e4SLinus Torvalds 26371da177e4SLinus Torvalds if (p1 == p2) { 2638f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 26391da177e4SLinus Torvalds return NULL; 26401da177e4SLinus Torvalds } 26411da177e4SLinus Torvalds 2642a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 26431da177e4SLinus Torvalds 2644e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2645e2761a11SOGAWA Hirofumi if (p) { 2646f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2647f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 26481da177e4SLinus Torvalds return p; 26491da177e4SLinus Torvalds } 26501da177e4SLinus Torvalds 2651e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2652e2761a11SOGAWA Hirofumi if (p) { 2653f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2654f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 26551da177e4SLinus Torvalds return p; 26561da177e4SLinus Torvalds } 26571da177e4SLinus Torvalds 2658f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2659d1b72cc6SMiklos Szeredi mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); 26601da177e4SLinus Torvalds return NULL; 26611da177e4SLinus Torvalds } 26624d359507SAl Viro EXPORT_SYMBOL(lock_rename); 26631da177e4SLinus Torvalds 26641da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 26651da177e4SLinus Torvalds { 26661b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 26671da177e4SLinus Torvalds if (p1 != p2) { 26681b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2669a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 26701da177e4SLinus Torvalds } 26711da177e4SLinus Torvalds } 26724d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 26731da177e4SLinus Torvalds 26744acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2675312b63fbSAl Viro bool want_excl) 26761da177e4SLinus Torvalds { 2677a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 26781da177e4SLinus Torvalds if (error) 26791da177e4SLinus Torvalds return error; 26801da177e4SLinus Torvalds 2681acfa4380SAl Viro if (!dir->i_op->create) 26821da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 26831da177e4SLinus Torvalds mode &= S_IALLUGO; 26841da177e4SLinus Torvalds mode |= S_IFREG; 26851da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 26861da177e4SLinus Torvalds if (error) 26871da177e4SLinus Torvalds return error; 2688312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2689a74574aaSStephen Smalley if (!error) 2690f38aa942SAmy Griffis fsnotify_create(dir, dentry); 26911da177e4SLinus Torvalds return error; 26921da177e4SLinus Torvalds } 26934d359507SAl Viro EXPORT_SYMBOL(vfs_create); 26941da177e4SLinus Torvalds 269573d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 26961da177e4SLinus Torvalds { 26973fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 26981da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 26991da177e4SLinus Torvalds int error; 27001da177e4SLinus Torvalds 2701bcda7652SAl Viro /* O_PATH? */ 2702bcda7652SAl Viro if (!acc_mode) 2703bcda7652SAl Viro return 0; 2704bcda7652SAl Viro 27051da177e4SLinus Torvalds if (!inode) 27061da177e4SLinus Torvalds return -ENOENT; 27071da177e4SLinus Torvalds 2708c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2709c8fe8f30SChristoph Hellwig case S_IFLNK: 27101da177e4SLinus Torvalds return -ELOOP; 2711c8fe8f30SChristoph Hellwig case S_IFDIR: 2712c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 27131da177e4SLinus Torvalds return -EISDIR; 2714c8fe8f30SChristoph Hellwig break; 2715c8fe8f30SChristoph Hellwig case S_IFBLK: 2716c8fe8f30SChristoph Hellwig case S_IFCHR: 27173fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 27181da177e4SLinus Torvalds return -EACCES; 2719c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2720c8fe8f30SChristoph Hellwig case S_IFIFO: 2721c8fe8f30SChristoph Hellwig case S_IFSOCK: 27221da177e4SLinus Torvalds flag &= ~O_TRUNC; 2723c8fe8f30SChristoph Hellwig break; 27244a3fd211SDave Hansen } 2725b41572e9SDave Hansen 27263fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2727b41572e9SDave Hansen if (error) 2728b41572e9SDave Hansen return error; 27296146f0d5SMimi Zohar 27301da177e4SLinus Torvalds /* 27311da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 27321da177e4SLinus Torvalds */ 27331da177e4SLinus Torvalds if (IS_APPEND(inode)) { 27348737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 27357715b521SAl Viro return -EPERM; 27361da177e4SLinus Torvalds if (flag & O_TRUNC) 27377715b521SAl Viro return -EPERM; 27381da177e4SLinus Torvalds } 27391da177e4SLinus Torvalds 27401da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 27412e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 27427715b521SAl Viro return -EPERM; 27431da177e4SLinus Torvalds 2744f3c7691eSJ. Bruce Fields return 0; 27457715b521SAl Viro } 27467715b521SAl Viro 2747e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 27487715b521SAl Viro { 2749e1181ee6SJeff Layton struct path *path = &filp->f_path; 27507715b521SAl Viro struct inode *inode = path->dentry->d_inode; 27517715b521SAl Viro int error = get_write_access(inode); 27521da177e4SLinus Torvalds if (error) 27537715b521SAl Viro return error; 27541da177e4SLinus Torvalds /* 27551da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 27561da177e4SLinus Torvalds */ 2757d7a06983SJeff Layton error = locks_verify_locked(filp); 2758be6d3e56SKentaro Takeda if (!error) 2759ea0d3ab2STetsuo Handa error = security_path_truncate(path); 27601da177e4SLinus Torvalds if (!error) { 27617715b521SAl Viro error = do_truncate(path->dentry, 0, 2762d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2763e1181ee6SJeff Layton filp); 27641da177e4SLinus Torvalds } 27651da177e4SLinus Torvalds put_write_access(inode); 2766acd0c935SMimi Zohar return error; 27671da177e4SLinus Torvalds } 27681da177e4SLinus Torvalds 2769d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2770d57999e1SDave Hansen { 27718a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 27728a5e929dSAl Viro flag--; 2773d57999e1SDave Hansen return flag; 2774d57999e1SDave Hansen } 2775d57999e1SDave Hansen 2776d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2777d18e9008SMiklos Szeredi { 2778d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2779d18e9008SMiklos Szeredi if (error) 2780d18e9008SMiklos Szeredi return error; 2781d18e9008SMiklos Szeredi 2782d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2783d18e9008SMiklos Szeredi if (error) 2784d18e9008SMiklos Szeredi return error; 2785d18e9008SMiklos Szeredi 2786d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2787d18e9008SMiklos Szeredi } 2788d18e9008SMiklos Szeredi 27891acf0af9SDavid Howells /* 27901acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 27911acf0af9SDavid Howells * dentry. 27921acf0af9SDavid Howells * 27931acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 27941acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 27951acf0af9SDavid Howells * 27961acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 27971acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 27981acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 27991acf0af9SDavid Howells * 28001acf0af9SDavid Howells * Returns an error code otherwise. 28011acf0af9SDavid Howells */ 28022675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 280330d90494SAl Viro struct path *path, struct file *file, 2804015c3bbcSMiklos Szeredi const struct open_flags *op, 280564894cf8SAl Viro bool got_write, bool need_lookup, 280647237687SAl Viro int *opened) 2807d18e9008SMiklos Szeredi { 2808d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2809d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2810d18e9008SMiklos Szeredi umode_t mode; 2811d18e9008SMiklos Szeredi int error; 2812d18e9008SMiklos Szeredi int acc_mode; 2813d18e9008SMiklos Szeredi int create_error = 0; 2814d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2815116cc022SMiklos Szeredi bool excl; 2816d18e9008SMiklos Szeredi 2817d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2818d18e9008SMiklos Szeredi 2819d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2820d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 28212675a4ebSAl Viro error = -ENOENT; 2822d18e9008SMiklos Szeredi goto out; 2823d18e9008SMiklos Szeredi } 2824d18e9008SMiklos Szeredi 282562b259d8SMiklos Szeredi mode = op->mode; 2826d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2827d18e9008SMiklos Szeredi mode &= ~current_umask(); 2828d18e9008SMiklos Szeredi 2829116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2830116cc022SMiklos Szeredi if (excl) 2831d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2832d18e9008SMiklos Szeredi 2833d18e9008SMiklos Szeredi /* 2834d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2835d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2836d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2837d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2838d18e9008SMiklos Szeredi * 2839d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2840d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2841d18e9008SMiklos Szeredi */ 284264894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 284364894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 284464894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2845d18e9008SMiklos Szeredi /* 2846d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2847d18e9008SMiklos Szeredi * back to lookup + open 2848d18e9008SMiklos Szeredi */ 2849d18e9008SMiklos Szeredi goto no_open; 2850d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2851d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 285264894cf8SAl Viro create_error = -EROFS; 2853d18e9008SMiklos Szeredi goto no_open; 2854d18e9008SMiklos Szeredi } else { 2855d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 285664894cf8SAl Viro create_error = -EROFS; 2857d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2858d18e9008SMiklos Szeredi } 2859d18e9008SMiklos Szeredi } 2860d18e9008SMiklos Szeredi 2861d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 286238227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2863d18e9008SMiklos Szeredi if (error) { 2864d18e9008SMiklos Szeredi create_error = error; 2865d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2866d18e9008SMiklos Szeredi goto no_open; 2867d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2868d18e9008SMiklos Szeredi } 2869d18e9008SMiklos Szeredi } 2870d18e9008SMiklos Szeredi 2871d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2872d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2873d18e9008SMiklos Szeredi 287430d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 287530d90494SAl Viro file->f_path.mnt = nd->path.mnt; 287630d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 287747237687SAl Viro opened); 2878d9585277SAl Viro if (error < 0) { 2879d9585277SAl Viro if (create_error && error == -ENOENT) 2880d9585277SAl Viro error = create_error; 2881d18e9008SMiklos Szeredi goto out; 2882d18e9008SMiklos Szeredi } 2883d18e9008SMiklos Szeredi 2884d9585277SAl Viro if (error) { /* returned 1, that is */ 288530d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 28862675a4ebSAl Viro error = -EIO; 2887d18e9008SMiklos Szeredi goto out; 2888d18e9008SMiklos Szeredi } 288930d90494SAl Viro if (file->f_path.dentry) { 2890d18e9008SMiklos Szeredi dput(dentry); 289130d90494SAl Viro dentry = file->f_path.dentry; 2892d18e9008SMiklos Szeredi } 289303da633aSAl Viro if (*opened & FILE_CREATED) 289403da633aSAl Viro fsnotify_create(dir, dentry); 289503da633aSAl Viro if (!dentry->d_inode) { 289603da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 289703da633aSAl Viro if (create_error) { 289862b2ce96SSage Weil error = create_error; 289962b2ce96SSage Weil goto out; 290062b2ce96SSage Weil } 290103da633aSAl Viro } else { 290203da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 290303da633aSAl Viro error = -EEXIST; 290403da633aSAl Viro goto out; 290503da633aSAl Viro } 290603da633aSAl Viro } 2907d18e9008SMiklos Szeredi goto looked_up; 2908d18e9008SMiklos Szeredi } 2909d18e9008SMiklos Szeredi 2910d18e9008SMiklos Szeredi /* 2911d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2912d18e9008SMiklos Szeredi * here. 2913d18e9008SMiklos Szeredi */ 291403da633aSAl Viro acc_mode = op->acc_mode; 291503da633aSAl Viro if (*opened & FILE_CREATED) { 291603da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 291703da633aSAl Viro fsnotify_create(dir, dentry); 291803da633aSAl Viro acc_mode = MAY_OPEN; 291903da633aSAl Viro } 29202675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 29212675a4ebSAl Viro if (error) 29222675a4ebSAl Viro fput(file); 2923d18e9008SMiklos Szeredi 2924d18e9008SMiklos Szeredi out: 2925d18e9008SMiklos Szeredi dput(dentry); 29262675a4ebSAl Viro return error; 2927d18e9008SMiklos Szeredi 2928d18e9008SMiklos Szeredi no_open: 2929d18e9008SMiklos Szeredi if (need_lookup) { 293072bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2931d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 29322675a4ebSAl Viro return PTR_ERR(dentry); 2933d18e9008SMiklos Szeredi 2934d18e9008SMiklos Szeredi if (create_error) { 2935d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2936d18e9008SMiklos Szeredi 29372675a4ebSAl Viro error = create_error; 2938d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2939d18e9008SMiklos Szeredi if (!dentry->d_inode) 2940d18e9008SMiklos Szeredi goto out; 2941d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2942d18e9008SMiklos Szeredi goto out; 2943d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2944e36cb0b8SDavid Howells d_is_reg(dentry)) { 2945d18e9008SMiklos Szeredi goto out; 2946d18e9008SMiklos Szeredi } 2947d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2948d18e9008SMiklos Szeredi } 2949d18e9008SMiklos Szeredi } 2950d18e9008SMiklos Szeredi looked_up: 2951d18e9008SMiklos Szeredi path->dentry = dentry; 2952d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 29532675a4ebSAl Viro return 1; 2954d18e9008SMiklos Szeredi } 2955d18e9008SMiklos Szeredi 295631e6b01fSNick Piggin /* 29571acf0af9SDavid Howells * Look up and maybe create and open the last component. 2958d58ffd35SMiklos Szeredi * 2959d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2960d58ffd35SMiklos Szeredi * 29611acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 29621acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 29631acf0af9SDavid Howells * 29641acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 29651acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 29661acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 29671acf0af9SDavid Howells * specified then a negative dentry may be returned. 29681acf0af9SDavid Howells * 29691acf0af9SDavid Howells * An error code is returned otherwise. 29701acf0af9SDavid Howells * 29711acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 29721acf0af9SDavid Howells * cleared otherwise prior to returning. 2973d58ffd35SMiklos Szeredi */ 29742675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 297530d90494SAl Viro struct file *file, 2976d58ffd35SMiklos Szeredi const struct open_flags *op, 297764894cf8SAl Viro bool got_write, int *opened) 2978d58ffd35SMiklos Szeredi { 2979d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 298054ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2981d58ffd35SMiklos Szeredi struct dentry *dentry; 2982d58ffd35SMiklos Szeredi int error; 298354ef4872SMiklos Szeredi bool need_lookup; 2984d58ffd35SMiklos Szeredi 298547237687SAl Viro *opened &= ~FILE_CREATED; 2986201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2987d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 29882675a4ebSAl Viro return PTR_ERR(dentry); 2989d58ffd35SMiklos Szeredi 2990d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2991d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2992d18e9008SMiklos Szeredi goto out_no_open; 2993d18e9008SMiklos Szeredi 2994d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 299564894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 299647237687SAl Viro need_lookup, opened); 2997d18e9008SMiklos Szeredi } 2998d18e9008SMiklos Szeredi 299954ef4872SMiklos Szeredi if (need_lookup) { 300054ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 300154ef4872SMiklos Szeredi 300272bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 300354ef4872SMiklos Szeredi if (IS_ERR(dentry)) 30042675a4ebSAl Viro return PTR_ERR(dentry); 300554ef4872SMiklos Szeredi } 300654ef4872SMiklos Szeredi 3007d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 3008d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 3009d58ffd35SMiklos Szeredi umode_t mode = op->mode; 3010d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 3011d58ffd35SMiklos Szeredi mode &= ~current_umask(); 3012d58ffd35SMiklos Szeredi /* 3013d58ffd35SMiklos Szeredi * This write is needed to ensure that a 3014d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 3015d58ffd35SMiklos Szeredi * the time when the file is created and when 3016d58ffd35SMiklos Szeredi * a permanent write count is taken through 3017015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 3018d58ffd35SMiklos Szeredi */ 301964894cf8SAl Viro if (!got_write) { 302064894cf8SAl Viro error = -EROFS; 3021d58ffd35SMiklos Szeredi goto out_dput; 302264894cf8SAl Viro } 302347237687SAl Viro *opened |= FILE_CREATED; 3024d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 3025d58ffd35SMiklos Szeredi if (error) 3026d58ffd35SMiklos Szeredi goto out_dput; 3027312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 3028312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 3029d58ffd35SMiklos Szeredi if (error) 3030d58ffd35SMiklos Szeredi goto out_dput; 3031d58ffd35SMiklos Szeredi } 3032d18e9008SMiklos Szeredi out_no_open: 3033d58ffd35SMiklos Szeredi path->dentry = dentry; 3034d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 30352675a4ebSAl Viro return 1; 3036d58ffd35SMiklos Szeredi 3037d58ffd35SMiklos Szeredi out_dput: 3038d58ffd35SMiklos Szeredi dput(dentry); 30392675a4ebSAl Viro return error; 3040d58ffd35SMiklos Szeredi } 3041d58ffd35SMiklos Szeredi 3042d58ffd35SMiklos Szeredi /* 3043fe2d35ffSAl Viro * Handle the last step of open() 304431e6b01fSNick Piggin */ 3045896475d5SAl Viro static int do_last(struct nameidata *nd, 304630d90494SAl Viro struct file *file, const struct open_flags *op, 3047669abf4eSJeff Layton int *opened, struct filename *name) 3048fb1cc555SAl Viro { 3049a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3050ca344a89SAl Viro int open_flag = op->open_flag; 305177d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 305264894cf8SAl Viro bool got_write = false; 3053bcda7652SAl Viro int acc_mode = op->acc_mode; 3054254cf582SAl Viro unsigned seq; 3055a1eb3315SMiklos Szeredi struct inode *inode; 305616b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 3057896475d5SAl Viro struct path path; 305816b1c1cdSMiklos Szeredi bool retried = false; 305916c2cd71SAl Viro int error; 3060fb1cc555SAl Viro 3061c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3062c3e380b0SAl Viro nd->flags |= op->intent; 3063c3e380b0SAl Viro 3064bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3065fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3066deb106c6SAl Viro if (unlikely(error)) 30672675a4ebSAl Viro return error; 3068e83db167SMiklos Szeredi goto finish_open; 30691f36f774SAl Viro } 3070a2c36b45SAl Viro 3071ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3072fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3073fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3074fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3075254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 307671574865SMiklos Szeredi if (likely(!error)) 307771574865SMiklos Szeredi goto finish_lookup; 307871574865SMiklos Szeredi 3079ce57dfc1SAl Viro if (error < 0) 3080deb106c6SAl Viro return error; 3081a1eb3315SMiklos Szeredi 308237d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 3083b6183df7SMiklos Szeredi } else { 3084fe2d35ffSAl Viro /* create side of things */ 3085a3fbbde7SAl Viro /* 3086b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3087b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3088b6183df7SMiklos Szeredi * about to look up 3089a3fbbde7SAl Viro */ 30909f1fafeeSAl Viro error = complete_walk(nd); 3091e8bb73dfSAl Viro if (error) 30922675a4ebSAl Viro return error; 3093fe2d35ffSAl Viro 309433e2208aSJeff Layton audit_inode(name, dir, LOOKUP_PARENT); 30951f36f774SAl Viro /* trailing slashes? */ 3096deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3097deb106c6SAl Viro return -EISDIR; 3098b6183df7SMiklos Szeredi } 30991f36f774SAl Viro 310016b1c1cdSMiklos Szeredi retry_lookup: 310164894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 310264894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 310364894cf8SAl Viro if (!error) 310464894cf8SAl Viro got_write = true; 310564894cf8SAl Viro /* 310664894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 310764894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 310864894cf8SAl Viro * dropping this one anyway. 310964894cf8SAl Viro */ 311064894cf8SAl Viro } 3111a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 3112896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 3113fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 3114fb1cc555SAl Viro 31152675a4ebSAl Viro if (error <= 0) { 31162675a4ebSAl Viro if (error) 3117d58ffd35SMiklos Szeredi goto out; 31186c0d46c4SAl Viro 311947237687SAl Viro if ((*opened & FILE_CREATED) || 3120496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 312177d660a8SMiklos Szeredi will_truncate = false; 3122d18e9008SMiklos Szeredi 3123adb5c247SJeff Layton audit_inode(name, file->f_path.dentry, 0); 3124d18e9008SMiklos Szeredi goto opened; 3125d18e9008SMiklos Szeredi } 3126d18e9008SMiklos Szeredi 312747237687SAl Viro if (*opened & FILE_CREATED) { 31289b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3129ca344a89SAl Viro open_flag &= ~O_TRUNC; 313077d660a8SMiklos Szeredi will_truncate = false; 3131bcda7652SAl Viro acc_mode = MAY_OPEN; 3132896475d5SAl Viro path_to_nameidata(&path, nd); 3133e83db167SMiklos Szeredi goto finish_open_created; 3134fb1cc555SAl Viro } 3135fb1cc555SAl Viro 3136fb1cc555SAl Viro /* 31373134f37eSJeff Layton * create/update audit record if it already exists. 3138fb1cc555SAl Viro */ 3139896475d5SAl Viro if (d_is_positive(path.dentry)) 3140896475d5SAl Viro audit_inode(name, path.dentry, 0); 3141fb1cc555SAl Viro 3142d18e9008SMiklos Szeredi /* 3143d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3144d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3145d18e9008SMiklos Szeredi * necessary...) 3146d18e9008SMiklos Szeredi */ 314764894cf8SAl Viro if (got_write) { 3148d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 314964894cf8SAl Viro got_write = false; 3150d18e9008SMiklos Szeredi } 3151d18e9008SMiklos Szeredi 3152deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3153deb106c6SAl Viro path_to_nameidata(&path, nd); 3154deb106c6SAl Viro return -EEXIST; 3155deb106c6SAl Viro } 3156fb1cc555SAl Viro 3157756daf26SNeilBrown error = follow_managed(&path, nd); 3158deb106c6SAl Viro if (unlikely(error < 0)) 3159deb106c6SAl Viro return error; 3160a3fbbde7SAl Viro 3161decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 316263afdfc7SDavid Howells inode = d_backing_inode(path.dentry); 3163254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3164deb106c6SAl Viro if (unlikely(d_is_negative(path.dentry))) { 3165896475d5SAl Viro path_to_nameidata(&path, nd); 3166deb106c6SAl Viro return -ENOENT; 316754c33e7fSMiklos Szeredi } 3168766c4cbfSAl Viro finish_lookup: 3169191d7f73SAl Viro if (nd->depth) 3170191d7f73SAl Viro put_link(nd); 3171181548c0SAl Viro error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW, 3172181548c0SAl Viro inode, seq); 3173deb106c6SAl Viro if (unlikely(error)) 3174d63ff28fSAl Viro return error; 3175fb1cc555SAl Viro 3176896475d5SAl Viro if (unlikely(d_is_symlink(path.dentry)) && !(open_flag & O_PATH)) { 3177896475d5SAl Viro path_to_nameidata(&path, nd); 3178deb106c6SAl Viro return -ELOOP; 3179a5cfe2d5SAl Viro } 3180a5cfe2d5SAl Viro 3181896475d5SAl Viro if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { 3182896475d5SAl Viro path_to_nameidata(&path, nd); 318316b1c1cdSMiklos Szeredi } else { 318416b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 3185896475d5SAl Viro save_parent.mnt = mntget(path.mnt); 3186896475d5SAl Viro nd->path.dentry = path.dentry; 318716b1c1cdSMiklos Szeredi 318816b1c1cdSMiklos Szeredi } 3189decf3400SMiklos Szeredi nd->inode = inode; 3190254cf582SAl Viro nd->seq = seq; 3191a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3192bc77daa7SAl Viro finish_open: 3193a3fbbde7SAl Viro error = complete_walk(nd); 319416b1c1cdSMiklos Szeredi if (error) { 319516b1c1cdSMiklos Szeredi path_put(&save_parent); 31962675a4ebSAl Viro return error; 319716b1c1cdSMiklos Szeredi } 3198bc77daa7SAl Viro audit_inode(name, nd->path.dentry, 0); 3199fb1cc555SAl Viro error = -EISDIR; 320044b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 32012675a4ebSAl Viro goto out; 3202af2f5542SMiklos Szeredi error = -ENOTDIR; 320344b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 32042675a4ebSAl Viro goto out; 32054bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 320677d660a8SMiklos Szeredi will_truncate = false; 32076c0d46c4SAl Viro 32080f9d1a10SAl Viro if (will_truncate) { 32090f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 32100f9d1a10SAl Viro if (error) 32112675a4ebSAl Viro goto out; 321264894cf8SAl Viro got_write = true; 32130f9d1a10SAl Viro } 3214e83db167SMiklos Szeredi finish_open_created: 3215bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3216ca344a89SAl Viro if (error) 32172675a4ebSAl Viro goto out; 32184aa7c634SMiklos Szeredi 32194aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 32204aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 32214aa7c634SMiklos Szeredi if (!error) { 32224aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 32234aa7c634SMiklos Szeredi } else { 322430d90494SAl Viro if (error == -EOPENSTALE) 3225f60dc3dbSMiklos Szeredi goto stale_open; 3226015c3bbcSMiklos Szeredi goto out; 3227f60dc3dbSMiklos Szeredi } 3228a8277b9bSMiklos Szeredi opened: 32292675a4ebSAl Viro error = open_check_o_direct(file); 3230015c3bbcSMiklos Szeredi if (error) 3231015c3bbcSMiklos Szeredi goto exit_fput; 32323034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3233aa4caadbSMiklos Szeredi if (error) 3234aa4caadbSMiklos Szeredi goto exit_fput; 3235aa4caadbSMiklos Szeredi 32360f9d1a10SAl Viro if (will_truncate) { 32372675a4ebSAl Viro error = handle_truncate(file); 3238aa4caadbSMiklos Szeredi if (error) 3239aa4caadbSMiklos Szeredi goto exit_fput; 32400f9d1a10SAl Viro } 3241ca344a89SAl Viro out: 324264894cf8SAl Viro if (got_write) 32430f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 324416b1c1cdSMiklos Szeredi path_put(&save_parent); 32452675a4ebSAl Viro return error; 3246fb1cc555SAl Viro 3247015c3bbcSMiklos Szeredi exit_fput: 32482675a4ebSAl Viro fput(file); 32492675a4ebSAl Viro goto out; 3250015c3bbcSMiklos Szeredi 3251f60dc3dbSMiklos Szeredi stale_open: 3252f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3253f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3254f60dc3dbSMiklos Szeredi goto out; 3255f60dc3dbSMiklos Szeredi 3256f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3257f60dc3dbSMiklos Szeredi path_put(&nd->path); 3258f60dc3dbSMiklos Szeredi nd->path = save_parent; 3259f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3260f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3261f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 326264894cf8SAl Viro if (got_write) { 3263f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 326464894cf8SAl Viro got_write = false; 3265f60dc3dbSMiklos Szeredi } 3266f60dc3dbSMiklos Szeredi retried = true; 3267f60dc3dbSMiklos Szeredi goto retry_lookup; 3268fb1cc555SAl Viro } 3269fb1cc555SAl Viro 327060545d0dSAl Viro static int do_tmpfile(int dfd, struct filename *pathname, 327160545d0dSAl Viro struct nameidata *nd, int flags, 327260545d0dSAl Viro const struct open_flags *op, 327360545d0dSAl Viro struct file *file, int *opened) 327460545d0dSAl Viro { 327560545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 327660545d0dSAl Viro struct dentry *dentry, *child; 327760545d0dSAl Viro struct inode *dir; 32785eb6b495SAl Viro int error = path_lookupat(dfd, pathname, 327960545d0dSAl Viro flags | LOOKUP_DIRECTORY, nd); 328060545d0dSAl Viro if (unlikely(error)) 328160545d0dSAl Viro return error; 328260545d0dSAl Viro error = mnt_want_write(nd->path.mnt); 328360545d0dSAl Viro if (unlikely(error)) 328460545d0dSAl Viro goto out; 328560545d0dSAl Viro /* we want directory to be writable */ 328660545d0dSAl Viro error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); 328760545d0dSAl Viro if (error) 328860545d0dSAl Viro goto out2; 328960545d0dSAl Viro dentry = nd->path.dentry; 329060545d0dSAl Viro dir = dentry->d_inode; 329160545d0dSAl Viro if (!dir->i_op->tmpfile) { 329260545d0dSAl Viro error = -EOPNOTSUPP; 329360545d0dSAl Viro goto out2; 329460545d0dSAl Viro } 329560545d0dSAl Viro child = d_alloc(dentry, &name); 329660545d0dSAl Viro if (unlikely(!child)) { 329760545d0dSAl Viro error = -ENOMEM; 329860545d0dSAl Viro goto out2; 329960545d0dSAl Viro } 330060545d0dSAl Viro nd->flags &= ~LOOKUP_DIRECTORY; 330160545d0dSAl Viro nd->flags |= op->intent; 330260545d0dSAl Viro dput(nd->path.dentry); 330360545d0dSAl Viro nd->path.dentry = child; 330460545d0dSAl Viro error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); 330560545d0dSAl Viro if (error) 330660545d0dSAl Viro goto out2; 330760545d0dSAl Viro audit_inode(pathname, nd->path.dentry, 0); 330869a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 330969a91c23SEric Rannaud error = may_open(&nd->path, MAY_OPEN, op->open_flag); 331060545d0dSAl Viro if (error) 331160545d0dSAl Viro goto out2; 331260545d0dSAl Viro file->f_path.mnt = nd->path.mnt; 331360545d0dSAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 331460545d0dSAl Viro if (error) 331560545d0dSAl Viro goto out2; 331660545d0dSAl Viro error = open_check_o_direct(file); 3317f4e0c30cSAl Viro if (error) { 331860545d0dSAl Viro fput(file); 3319f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3320f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3321f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3322f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3323f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3324f4e0c30cSAl Viro } 332560545d0dSAl Viro out2: 332660545d0dSAl Viro mnt_drop_write(nd->path.mnt); 332760545d0dSAl Viro out: 332860545d0dSAl Viro path_put(&nd->path); 332960545d0dSAl Viro return error; 333060545d0dSAl Viro } 333160545d0dSAl Viro 3332669abf4eSJeff Layton static struct file *path_openat(int dfd, struct filename *pathname, 333373d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 33341da177e4SLinus Torvalds { 3335368ee9baSAl Viro const char *s; 333630d90494SAl Viro struct file *file; 333747237687SAl Viro int opened = 0; 333813aab428SAl Viro int error; 333931e6b01fSNick Piggin 334030d90494SAl Viro file = get_empty_filp(); 33411afc99beSAl Viro if (IS_ERR(file)) 33421afc99beSAl Viro return file; 334331e6b01fSNick Piggin 334430d90494SAl Viro file->f_flags = op->open_flag; 334531e6b01fSNick Piggin 3346bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 334760545d0dSAl Viro error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); 3348f15133dfSAl Viro goto out2; 334960545d0dSAl Viro } 335060545d0dSAl Viro 3351368ee9baSAl Viro s = path_init(dfd, pathname, flags, nd); 3352368ee9baSAl Viro if (IS_ERR(s)) { 3353368ee9baSAl Viro put_filp(file); 3354368ee9baSAl Viro return ERR_CAST(s); 3355368ee9baSAl Viro } 33563bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 33573bdba28bSAl Viro (error = do_last(nd, file, op, &opened, pathname)) > 0) { 335873d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 33593bdba28bSAl Viro s = trailing_symlink(nd); 33603bdba28bSAl Viro if (IS_ERR(s)) { 33613bdba28bSAl Viro error = PTR_ERR(s); 33622675a4ebSAl Viro break; 3363806b681cSAl Viro } 33643bdba28bSAl Viro } 3365deb106c6SAl Viro terminate_walk(nd); 3366893b7775SAl Viro path_cleanup(nd); 3367f15133dfSAl Viro out2: 33682675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 33692675a4ebSAl Viro BUG_ON(!error); 337030d90494SAl Viro put_filp(file); 3371015c3bbcSMiklos Szeredi } 33722675a4ebSAl Viro if (unlikely(error)) { 33732675a4ebSAl Viro if (error == -EOPENSTALE) { 33742675a4ebSAl Viro if (flags & LOOKUP_RCU) 33752675a4ebSAl Viro error = -ECHILD; 33762675a4ebSAl Viro else 33772675a4ebSAl Viro error = -ESTALE; 33782675a4ebSAl Viro } 33792675a4ebSAl Viro file = ERR_PTR(error); 33802675a4ebSAl Viro } 33812675a4ebSAl Viro return file; 3382de459215SKirill Korotaev } 33831da177e4SLinus Torvalds 3384669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3385f9652e10SAl Viro const struct open_flags *op) 338613aab428SAl Viro { 3387756daf26SNeilBrown struct nameidata nd, *saved_nd = set_nameidata(&nd); 3388f9652e10SAl Viro int flags = op->lookup_flags; 338913aab428SAl Viro struct file *filp; 339013aab428SAl Viro 339173d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 339213aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 339373d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 339413aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 339573d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 3396756daf26SNeilBrown restore_nameidata(saved_nd); 339713aab428SAl Viro return filp; 339813aab428SAl Viro } 339913aab428SAl Viro 340073d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3401f9652e10SAl Viro const char *name, const struct open_flags *op) 340273d049a4SAl Viro { 3403756daf26SNeilBrown struct nameidata nd, *saved_nd; 340473d049a4SAl Viro struct file *file; 340551689104SPaul Moore struct filename *filename; 3406f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 340773d049a4SAl Viro 340873d049a4SAl Viro nd.root.mnt = mnt; 340973d049a4SAl Viro nd.root.dentry = dentry; 341073d049a4SAl Viro 3411b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 341273d049a4SAl Viro return ERR_PTR(-ELOOP); 341373d049a4SAl Viro 341451689104SPaul Moore filename = getname_kernel(name); 341551689104SPaul Moore if (unlikely(IS_ERR(filename))) 341651689104SPaul Moore return ERR_CAST(filename); 341751689104SPaul Moore 3418756daf26SNeilBrown saved_nd = set_nameidata(&nd); 341951689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_RCU); 342073d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 342151689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags); 342273d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 342351689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_REVAL); 3424756daf26SNeilBrown restore_nameidata(saved_nd); 342551689104SPaul Moore putname(filename); 342673d049a4SAl Viro return file; 342773d049a4SAl Viro } 342873d049a4SAl Viro 3429fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 34301ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 34311da177e4SLinus Torvalds { 3432c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3433ed75e95dSAl Viro struct nameidata nd; 3434c30dabfeSJan Kara int err2; 34351ac12b4bSJeff Layton int error; 34361ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 34371ac12b4bSJeff Layton 34381ac12b4bSJeff Layton /* 34391ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 34401ac12b4bSJeff Layton * other flags passed in are ignored! 34411ac12b4bSJeff Layton */ 34421ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 34431ac12b4bSJeff Layton 34448bcb77faSAl Viro error = filename_parentat(dfd, name, lookup_flags, &nd); 3445ed75e95dSAl Viro if (error) 3446ed75e95dSAl Viro return ERR_PTR(error); 34471da177e4SLinus Torvalds 3448c663e5d8SChristoph Hellwig /* 3449c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3450c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3451c663e5d8SChristoph Hellwig */ 3452ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 3453ed75e95dSAl Viro goto out; 3454ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 3455ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 3456c663e5d8SChristoph Hellwig 3457c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3458c30dabfeSJan Kara err2 = mnt_want_write(nd.path.mnt); 3459c663e5d8SChristoph Hellwig /* 3460c663e5d8SChristoph Hellwig * Do the final lookup. 3461c663e5d8SChristoph Hellwig */ 3462ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 34636a9f40d6SAl Viro dentry = __lookup_hash(&nd.last, nd.path.dentry, nd.flags); 34641da177e4SLinus Torvalds if (IS_ERR(dentry)) 3465a8104a9fSAl Viro goto unlock; 3466c663e5d8SChristoph Hellwig 3467a8104a9fSAl Viro error = -EEXIST; 3468b18825a7SDavid Howells if (d_is_positive(dentry)) 3469a8104a9fSAl Viro goto fail; 3470b18825a7SDavid Howells 3471c663e5d8SChristoph Hellwig /* 3472c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3473c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3474c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3475c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3476c663e5d8SChristoph Hellwig */ 3477ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 3478a8104a9fSAl Viro error = -ENOENT; 3479ed75e95dSAl Viro goto fail; 3480e9baf6e5SAl Viro } 3481c30dabfeSJan Kara if (unlikely(err2)) { 3482c30dabfeSJan Kara error = err2; 3483a8104a9fSAl Viro goto fail; 3484c30dabfeSJan Kara } 3485ed75e95dSAl Viro *path = nd.path; 3486e9baf6e5SAl Viro return dentry; 34871da177e4SLinus Torvalds fail: 3488a8104a9fSAl Viro dput(dentry); 3489a8104a9fSAl Viro dentry = ERR_PTR(error); 3490a8104a9fSAl Viro unlock: 3491dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3492c30dabfeSJan Kara if (!err2) 3493c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 3494ed75e95dSAl Viro out: 3495dae6ad8fSAl Viro path_put(&nd.path); 3496ed75e95dSAl Viro return dentry; 3497dae6ad8fSAl Viro } 3498fa14a0b8SAl Viro 3499fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3500fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3501fa14a0b8SAl Viro { 350251689104SPaul Moore struct filename *filename = getname_kernel(pathname); 350351689104SPaul Moore struct dentry *res; 350451689104SPaul Moore 350551689104SPaul Moore if (IS_ERR(filename)) 350651689104SPaul Moore return ERR_CAST(filename); 350751689104SPaul Moore res = filename_create(dfd, filename, path, lookup_flags); 350851689104SPaul Moore putname(filename); 350951689104SPaul Moore return res; 3510fa14a0b8SAl Viro } 3511dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3512dae6ad8fSAl Viro 3513921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3514921a1650SAl Viro { 3515921a1650SAl Viro dput(dentry); 3516921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3517a8104a9fSAl Viro mnt_drop_write(path->mnt); 3518921a1650SAl Viro path_put(path); 3519921a1650SAl Viro } 3520921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3521921a1650SAl Viro 35221ac12b4bSJeff Layton struct dentry *user_path_create(int dfd, const char __user *pathname, 35231ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3524dae6ad8fSAl Viro { 352591a27b2aSJeff Layton struct filename *tmp = getname(pathname); 3526dae6ad8fSAl Viro struct dentry *res; 3527dae6ad8fSAl Viro if (IS_ERR(tmp)) 3528dae6ad8fSAl Viro return ERR_CAST(tmp); 3529fa14a0b8SAl Viro res = filename_create(dfd, tmp, path, lookup_flags); 3530dae6ad8fSAl Viro putname(tmp); 3531dae6ad8fSAl Viro return res; 3532dae6ad8fSAl Viro } 3533dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3534dae6ad8fSAl Viro 35351a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 35361da177e4SLinus Torvalds { 3537a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35381da177e4SLinus Torvalds 35391da177e4SLinus Torvalds if (error) 35401da177e4SLinus Torvalds return error; 35411da177e4SLinus Torvalds 3542975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 35431da177e4SLinus Torvalds return -EPERM; 35441da177e4SLinus Torvalds 3545acfa4380SAl Viro if (!dir->i_op->mknod) 35461da177e4SLinus Torvalds return -EPERM; 35471da177e4SLinus Torvalds 354808ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 354908ce5f16SSerge E. Hallyn if (error) 355008ce5f16SSerge E. Hallyn return error; 355108ce5f16SSerge E. Hallyn 35521da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 35531da177e4SLinus Torvalds if (error) 35541da177e4SLinus Torvalds return error; 35551da177e4SLinus Torvalds 35561da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3557a74574aaSStephen Smalley if (!error) 3558f38aa942SAmy Griffis fsnotify_create(dir, dentry); 35591da177e4SLinus Torvalds return error; 35601da177e4SLinus Torvalds } 35614d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 35621da177e4SLinus Torvalds 3563f69aac00SAl Viro static int may_mknod(umode_t mode) 3564463c3197SDave Hansen { 3565463c3197SDave Hansen switch (mode & S_IFMT) { 3566463c3197SDave Hansen case S_IFREG: 3567463c3197SDave Hansen case S_IFCHR: 3568463c3197SDave Hansen case S_IFBLK: 3569463c3197SDave Hansen case S_IFIFO: 3570463c3197SDave Hansen case S_IFSOCK: 3571463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3572463c3197SDave Hansen return 0; 3573463c3197SDave Hansen case S_IFDIR: 3574463c3197SDave Hansen return -EPERM; 3575463c3197SDave Hansen default: 3576463c3197SDave Hansen return -EINVAL; 3577463c3197SDave Hansen } 3578463c3197SDave Hansen } 3579463c3197SDave Hansen 35808208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 35812e4d0924SHeiko Carstens unsigned, dev) 35821da177e4SLinus Torvalds { 35831da177e4SLinus Torvalds struct dentry *dentry; 3584dae6ad8fSAl Viro struct path path; 3585dae6ad8fSAl Viro int error; 3586972567f1SJeff Layton unsigned int lookup_flags = 0; 35871da177e4SLinus Torvalds 35888e4bfca1SAl Viro error = may_mknod(mode); 35898e4bfca1SAl Viro if (error) 35908e4bfca1SAl Viro return error; 3591972567f1SJeff Layton retry: 3592972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3593dae6ad8fSAl Viro if (IS_ERR(dentry)) 3594dae6ad8fSAl Viro return PTR_ERR(dentry); 35952ad94ae6SAl Viro 3596dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3597ce3b0f8dSAl Viro mode &= ~current_umask(); 3598dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3599be6d3e56SKentaro Takeda if (error) 3600a8104a9fSAl Viro goto out; 36011da177e4SLinus Torvalds switch (mode & S_IFMT) { 36021da177e4SLinus Torvalds case 0: case S_IFREG: 3603312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 36041da177e4SLinus Torvalds break; 36051da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3606dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 36071da177e4SLinus Torvalds new_decode_dev(dev)); 36081da177e4SLinus Torvalds break; 36091da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3610dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 36111da177e4SLinus Torvalds break; 36121da177e4SLinus Torvalds } 3613a8104a9fSAl Viro out: 3614921a1650SAl Viro done_path_create(&path, dentry); 3615972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3616972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3617972567f1SJeff Layton goto retry; 3618972567f1SJeff Layton } 36191da177e4SLinus Torvalds return error; 36201da177e4SLinus Torvalds } 36211da177e4SLinus Torvalds 36228208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 36235590ff0dSUlrich Drepper { 36245590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 36255590ff0dSUlrich Drepper } 36265590ff0dSUlrich Drepper 362718bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 36281da177e4SLinus Torvalds { 3629a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36308de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 36311da177e4SLinus Torvalds 36321da177e4SLinus Torvalds if (error) 36331da177e4SLinus Torvalds return error; 36341da177e4SLinus Torvalds 3635acfa4380SAl Viro if (!dir->i_op->mkdir) 36361da177e4SLinus Torvalds return -EPERM; 36371da177e4SLinus Torvalds 36381da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 36391da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 36401da177e4SLinus Torvalds if (error) 36411da177e4SLinus Torvalds return error; 36421da177e4SLinus Torvalds 36438de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 36448de52778SAl Viro return -EMLINK; 36458de52778SAl Viro 36461da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3647a74574aaSStephen Smalley if (!error) 3648f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 36491da177e4SLinus Torvalds return error; 36501da177e4SLinus Torvalds } 36514d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 36521da177e4SLinus Torvalds 3653a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 36541da177e4SLinus Torvalds { 36556902d925SDave Hansen struct dentry *dentry; 3656dae6ad8fSAl Viro struct path path; 3657dae6ad8fSAl Viro int error; 3658b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 36591da177e4SLinus Torvalds 3660b76d8b82SJeff Layton retry: 3661b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 36626902d925SDave Hansen if (IS_ERR(dentry)) 3663dae6ad8fSAl Viro return PTR_ERR(dentry); 36646902d925SDave Hansen 3665dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3666ce3b0f8dSAl Viro mode &= ~current_umask(); 3667dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3668a8104a9fSAl Viro if (!error) 3669dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3670921a1650SAl Viro done_path_create(&path, dentry); 3671b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3672b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3673b76d8b82SJeff Layton goto retry; 3674b76d8b82SJeff Layton } 36751da177e4SLinus Torvalds return error; 36761da177e4SLinus Torvalds } 36771da177e4SLinus Torvalds 3678a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 36795590ff0dSUlrich Drepper { 36805590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 36815590ff0dSUlrich Drepper } 36825590ff0dSUlrich Drepper 36831da177e4SLinus Torvalds /* 3684a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3685c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3686a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3687a71905f0SSage Weil * then we drop the dentry now. 36881da177e4SLinus Torvalds * 36891da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 36901da177e4SLinus Torvalds * do a 36911da177e4SLinus Torvalds * 36921da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 36931da177e4SLinus Torvalds * return -EBUSY; 36941da177e4SLinus Torvalds * 36951da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 36961da177e4SLinus Torvalds * that is still in use by something else.. 36971da177e4SLinus Torvalds */ 36981da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 36991da177e4SLinus Torvalds { 37001da177e4SLinus Torvalds shrink_dcache_parent(dentry); 37011da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 370298474236SWaiman Long if (dentry->d_lockref.count == 1) 37031da177e4SLinus Torvalds __d_drop(dentry); 37041da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 37051da177e4SLinus Torvalds } 37064d359507SAl Viro EXPORT_SYMBOL(dentry_unhash); 37071da177e4SLinus Torvalds 37081da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 37091da177e4SLinus Torvalds { 37101da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 37111da177e4SLinus Torvalds 37121da177e4SLinus Torvalds if (error) 37131da177e4SLinus Torvalds return error; 37141da177e4SLinus Torvalds 3715acfa4380SAl Viro if (!dir->i_op->rmdir) 37161da177e4SLinus Torvalds return -EPERM; 37171da177e4SLinus Torvalds 37181d2ef590SAl Viro dget(dentry); 37191b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3720912dbc15SSage Weil 37211da177e4SLinus Torvalds error = -EBUSY; 37227af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3723912dbc15SSage Weil goto out; 3724912dbc15SSage Weil 37251da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3726912dbc15SSage Weil if (error) 3727912dbc15SSage Weil goto out; 3728912dbc15SSage Weil 37293cebde24SSage Weil shrink_dcache_parent(dentry); 37301da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3731912dbc15SSage Weil if (error) 3732912dbc15SSage Weil goto out; 3733912dbc15SSage Weil 37341da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3735d83c49f3SAl Viro dont_mount(dentry); 37368ed936b5SEric W. Biederman detach_mounts(dentry); 37371da177e4SLinus Torvalds 3738912dbc15SSage Weil out: 3739912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 37401d2ef590SAl Viro dput(dentry); 3741912dbc15SSage Weil if (!error) 3742912dbc15SSage Weil d_delete(dentry); 37431da177e4SLinus Torvalds return error; 37441da177e4SLinus Torvalds } 37454d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 37461da177e4SLinus Torvalds 37475590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 37481da177e4SLinus Torvalds { 37491da177e4SLinus Torvalds int error = 0; 375091a27b2aSJeff Layton struct filename *name; 37511da177e4SLinus Torvalds struct dentry *dentry; 3752f5beed75SAl Viro struct path path; 3753f5beed75SAl Viro struct qstr last; 3754f5beed75SAl Viro int type; 3755c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3756c6ee9206SJeff Layton retry: 3757f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3758f5beed75SAl Viro &path, &last, &type, lookup_flags); 375991a27b2aSJeff Layton if (IS_ERR(name)) 376091a27b2aSJeff Layton return PTR_ERR(name); 37611da177e4SLinus Torvalds 3762f5beed75SAl Viro switch (type) { 37631da177e4SLinus Torvalds case LAST_DOTDOT: 37641da177e4SLinus Torvalds error = -ENOTEMPTY; 37651da177e4SLinus Torvalds goto exit1; 37661da177e4SLinus Torvalds case LAST_DOT: 37671da177e4SLinus Torvalds error = -EINVAL; 37681da177e4SLinus Torvalds goto exit1; 37691da177e4SLinus Torvalds case LAST_ROOT: 37701da177e4SLinus Torvalds error = -EBUSY; 37711da177e4SLinus Torvalds goto exit1; 37721da177e4SLinus Torvalds } 37730612d9fbSOGAWA Hirofumi 3774f5beed75SAl Viro error = mnt_want_write(path.mnt); 3775c30dabfeSJan Kara if (error) 3776c30dabfeSJan Kara goto exit1; 37770612d9fbSOGAWA Hirofumi 3778f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3779f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 37801da177e4SLinus Torvalds error = PTR_ERR(dentry); 37816902d925SDave Hansen if (IS_ERR(dentry)) 37826902d925SDave Hansen goto exit2; 3783e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3784e6bc45d6STheodore Ts'o error = -ENOENT; 3785e6bc45d6STheodore Ts'o goto exit3; 3786e6bc45d6STheodore Ts'o } 3787f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3788be6d3e56SKentaro Takeda if (error) 3789c30dabfeSJan Kara goto exit3; 3790f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 37910622753bSDave Hansen exit3: 37921da177e4SLinus Torvalds dput(dentry); 37936902d925SDave Hansen exit2: 3794f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 3795f5beed75SAl Viro mnt_drop_write(path.mnt); 37961da177e4SLinus Torvalds exit1: 3797f5beed75SAl Viro path_put(&path); 37981da177e4SLinus Torvalds putname(name); 3799c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3800c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3801c6ee9206SJeff Layton goto retry; 3802c6ee9206SJeff Layton } 38031da177e4SLinus Torvalds return error; 38041da177e4SLinus Torvalds } 38051da177e4SLinus Torvalds 38063cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 38075590ff0dSUlrich Drepper { 38085590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 38095590ff0dSUlrich Drepper } 38105590ff0dSUlrich Drepper 3811b21996e3SJ. Bruce Fields /** 3812b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3813b21996e3SJ. Bruce Fields * @dir: parent directory 3814b21996e3SJ. Bruce Fields * @dentry: victim 3815b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3816b21996e3SJ. Bruce Fields * 3817b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3818b21996e3SJ. Bruce Fields * 3819b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3820b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3821b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3822b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3823b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3824b21996e3SJ. Bruce Fields * 3825b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3826b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3827b21996e3SJ. Bruce Fields * to be NFS exported. 3828b21996e3SJ. Bruce Fields */ 3829b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 38301da177e4SLinus Torvalds { 38319accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 38321da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 38331da177e4SLinus Torvalds 38341da177e4SLinus Torvalds if (error) 38351da177e4SLinus Torvalds return error; 38361da177e4SLinus Torvalds 3837acfa4380SAl Viro if (!dir->i_op->unlink) 38381da177e4SLinus Torvalds return -EPERM; 38391da177e4SLinus Torvalds 38409accbb97SJ. Bruce Fields mutex_lock(&target->i_mutex); 38418ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 38421da177e4SLinus Torvalds error = -EBUSY; 38431da177e4SLinus Torvalds else { 38441da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3845bec1052eSAl Viro if (!error) { 38465a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 38475a14696cSJ. Bruce Fields if (error) 3848b21996e3SJ. Bruce Fields goto out; 38491da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 38508ed936b5SEric W. Biederman if (!error) { 3851d83c49f3SAl Viro dont_mount(dentry); 38528ed936b5SEric W. Biederman detach_mounts(dentry); 38538ed936b5SEric W. Biederman } 3854bec1052eSAl Viro } 38551da177e4SLinus Torvalds } 3856b21996e3SJ. Bruce Fields out: 38579accbb97SJ. Bruce Fields mutex_unlock(&target->i_mutex); 38581da177e4SLinus Torvalds 38591da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 38601da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 38619accbb97SJ. Bruce Fields fsnotify_link_count(target); 38621da177e4SLinus Torvalds d_delete(dentry); 38631da177e4SLinus Torvalds } 38640eeca283SRobert Love 38651da177e4SLinus Torvalds return error; 38661da177e4SLinus Torvalds } 38674d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 38681da177e4SLinus Torvalds 38691da177e4SLinus Torvalds /* 38701da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 38711b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 38721da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 38731da177e4SLinus Torvalds * while waiting on the I/O. 38741da177e4SLinus Torvalds */ 38755590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 38761da177e4SLinus Torvalds { 38772ad94ae6SAl Viro int error; 387891a27b2aSJeff Layton struct filename *name; 38791da177e4SLinus Torvalds struct dentry *dentry; 3880f5beed75SAl Viro struct path path; 3881f5beed75SAl Viro struct qstr last; 3882f5beed75SAl Viro int type; 38831da177e4SLinus Torvalds struct inode *inode = NULL; 3884b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 38855d18f813SJeff Layton unsigned int lookup_flags = 0; 38865d18f813SJeff Layton retry: 3887f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3888f5beed75SAl Viro &path, &last, &type, lookup_flags); 388991a27b2aSJeff Layton if (IS_ERR(name)) 389091a27b2aSJeff Layton return PTR_ERR(name); 38912ad94ae6SAl Viro 38921da177e4SLinus Torvalds error = -EISDIR; 3893f5beed75SAl Viro if (type != LAST_NORM) 38941da177e4SLinus Torvalds goto exit1; 38950612d9fbSOGAWA Hirofumi 3896f5beed75SAl Viro error = mnt_want_write(path.mnt); 3897c30dabfeSJan Kara if (error) 3898c30dabfeSJan Kara goto exit1; 3899b21996e3SJ. Bruce Fields retry_deleg: 3900f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3901f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 39021da177e4SLinus Torvalds error = PTR_ERR(dentry); 39031da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 39041da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3905f5beed75SAl Viro if (last.name[last.len]) 390650338b88STörök Edwin goto slashes; 39071da177e4SLinus Torvalds inode = dentry->d_inode; 3908b18825a7SDavid Howells if (d_is_negative(dentry)) 3909e6bc45d6STheodore Ts'o goto slashes; 39107de9c6eeSAl Viro ihold(inode); 3911f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3912be6d3e56SKentaro Takeda if (error) 3913c30dabfeSJan Kara goto exit2; 3914f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 39151da177e4SLinus Torvalds exit2: 39161da177e4SLinus Torvalds dput(dentry); 39171da177e4SLinus Torvalds } 3918f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 39191da177e4SLinus Torvalds if (inode) 39201da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3921b21996e3SJ. Bruce Fields inode = NULL; 3922b21996e3SJ. Bruce Fields if (delegated_inode) { 39235a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3924b21996e3SJ. Bruce Fields if (!error) 3925b21996e3SJ. Bruce Fields goto retry_deleg; 3926b21996e3SJ. Bruce Fields } 3927f5beed75SAl Viro mnt_drop_write(path.mnt); 39281da177e4SLinus Torvalds exit1: 3929f5beed75SAl Viro path_put(&path); 39301da177e4SLinus Torvalds putname(name); 39315d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 39325d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 39335d18f813SJeff Layton inode = NULL; 39345d18f813SJeff Layton goto retry; 39355d18f813SJeff Layton } 39361da177e4SLinus Torvalds return error; 39371da177e4SLinus Torvalds 39381da177e4SLinus Torvalds slashes: 3939b18825a7SDavid Howells if (d_is_negative(dentry)) 3940b18825a7SDavid Howells error = -ENOENT; 394144b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3942b18825a7SDavid Howells error = -EISDIR; 3943b18825a7SDavid Howells else 3944b18825a7SDavid Howells error = -ENOTDIR; 39451da177e4SLinus Torvalds goto exit2; 39461da177e4SLinus Torvalds } 39471da177e4SLinus Torvalds 39482e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 39495590ff0dSUlrich Drepper { 39505590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 39515590ff0dSUlrich Drepper return -EINVAL; 39525590ff0dSUlrich Drepper 39535590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 39545590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 39555590ff0dSUlrich Drepper 39565590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 39575590ff0dSUlrich Drepper } 39585590ff0dSUlrich Drepper 39593480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 39605590ff0dSUlrich Drepper { 39615590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 39625590ff0dSUlrich Drepper } 39635590ff0dSUlrich Drepper 3964db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 39651da177e4SLinus Torvalds { 3966a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 39671da177e4SLinus Torvalds 39681da177e4SLinus Torvalds if (error) 39691da177e4SLinus Torvalds return error; 39701da177e4SLinus Torvalds 3971acfa4380SAl Viro if (!dir->i_op->symlink) 39721da177e4SLinus Torvalds return -EPERM; 39731da177e4SLinus Torvalds 39741da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 39751da177e4SLinus Torvalds if (error) 39761da177e4SLinus Torvalds return error; 39771da177e4SLinus Torvalds 39781da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3979a74574aaSStephen Smalley if (!error) 3980f38aa942SAmy Griffis fsnotify_create(dir, dentry); 39811da177e4SLinus Torvalds return error; 39821da177e4SLinus Torvalds } 39834d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 39841da177e4SLinus Torvalds 39852e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 39862e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 39871da177e4SLinus Torvalds { 39882ad94ae6SAl Viro int error; 398991a27b2aSJeff Layton struct filename *from; 39906902d925SDave Hansen struct dentry *dentry; 3991dae6ad8fSAl Viro struct path path; 3992f46d3567SJeff Layton unsigned int lookup_flags = 0; 39931da177e4SLinus Torvalds 39941da177e4SLinus Torvalds from = getname(oldname); 39951da177e4SLinus Torvalds if (IS_ERR(from)) 39961da177e4SLinus Torvalds return PTR_ERR(from); 3997f46d3567SJeff Layton retry: 3998f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 39991da177e4SLinus Torvalds error = PTR_ERR(dentry); 40006902d925SDave Hansen if (IS_ERR(dentry)) 4001dae6ad8fSAl Viro goto out_putname; 40026902d925SDave Hansen 400391a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4004a8104a9fSAl Viro if (!error) 400591a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4006921a1650SAl Viro done_path_create(&path, dentry); 4007f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4008f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4009f46d3567SJeff Layton goto retry; 4010f46d3567SJeff Layton } 40116902d925SDave Hansen out_putname: 40121da177e4SLinus Torvalds putname(from); 40131da177e4SLinus Torvalds return error; 40141da177e4SLinus Torvalds } 40151da177e4SLinus Torvalds 40163480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 40175590ff0dSUlrich Drepper { 40185590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 40195590ff0dSUlrich Drepper } 40205590ff0dSUlrich Drepper 4021146a8595SJ. Bruce Fields /** 4022146a8595SJ. Bruce Fields * vfs_link - create a new link 4023146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4024146a8595SJ. Bruce Fields * @dir: new parent 4025146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4026146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4027146a8595SJ. Bruce Fields * 4028146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4029146a8595SJ. Bruce Fields * 4030146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4031146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4032146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4033146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4034146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4035146a8595SJ. Bruce Fields * 4036146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4037146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4038146a8595SJ. Bruce Fields * to be NFS exported. 4039146a8595SJ. Bruce Fields */ 4040146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 40411da177e4SLinus Torvalds { 40421da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 40438de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 40441da177e4SLinus Torvalds int error; 40451da177e4SLinus Torvalds 40461da177e4SLinus Torvalds if (!inode) 40471da177e4SLinus Torvalds return -ENOENT; 40481da177e4SLinus Torvalds 4049a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 40501da177e4SLinus Torvalds if (error) 40511da177e4SLinus Torvalds return error; 40521da177e4SLinus Torvalds 40531da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 40541da177e4SLinus Torvalds return -EXDEV; 40551da177e4SLinus Torvalds 40561da177e4SLinus Torvalds /* 40571da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 40581da177e4SLinus Torvalds */ 40591da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 40601da177e4SLinus Torvalds return -EPERM; 4061acfa4380SAl Viro if (!dir->i_op->link) 40621da177e4SLinus Torvalds return -EPERM; 40637e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 40641da177e4SLinus Torvalds return -EPERM; 40651da177e4SLinus Torvalds 40661da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 40671da177e4SLinus Torvalds if (error) 40681da177e4SLinus Torvalds return error; 40691da177e4SLinus Torvalds 40707e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 4071aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4072f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4073aae8a97dSAneesh Kumar K.V error = -ENOENT; 40748de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 40758de52778SAl Viro error = -EMLINK; 4076146a8595SJ. Bruce Fields else { 4077146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4078146a8595SJ. Bruce Fields if (!error) 40791da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4080146a8595SJ. Bruce Fields } 4081f4e0c30cSAl Viro 4082f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4083f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4084f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4085f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4086f4e0c30cSAl Viro } 40877e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 4088e31e14ecSStephen Smalley if (!error) 40897e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 40901da177e4SLinus Torvalds return error; 40911da177e4SLinus Torvalds } 40924d359507SAl Viro EXPORT_SYMBOL(vfs_link); 40931da177e4SLinus Torvalds 40941da177e4SLinus Torvalds /* 40951da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 40961da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 40971da177e4SLinus Torvalds * newname. --KAB 40981da177e4SLinus Torvalds * 40991da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 41001da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 41011da177e4SLinus Torvalds * and other special files. --ADM 41021da177e4SLinus Torvalds */ 41032e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 41042e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 41051da177e4SLinus Torvalds { 41061da177e4SLinus Torvalds struct dentry *new_dentry; 4107dae6ad8fSAl Viro struct path old_path, new_path; 4108146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 410911a7b371SAneesh Kumar K.V int how = 0; 41101da177e4SLinus Torvalds int error; 41111da177e4SLinus Torvalds 411211a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4113c04030e1SUlrich Drepper return -EINVAL; 411411a7b371SAneesh Kumar K.V /* 4115f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4116f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4117f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 411811a7b371SAneesh Kumar K.V */ 4119f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4120f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4121f0cc6ffbSLinus Torvalds return -ENOENT; 412211a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4123f0cc6ffbSLinus Torvalds } 4124c04030e1SUlrich Drepper 412511a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 412611a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4127442e31caSJeff Layton retry: 412811a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 41291da177e4SLinus Torvalds if (error) 41302ad94ae6SAl Viro return error; 41312ad94ae6SAl Viro 4132442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4133442e31caSJeff Layton (how & LOOKUP_REVAL)); 41341da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 41356902d925SDave Hansen if (IS_ERR(new_dentry)) 4136dae6ad8fSAl Viro goto out; 4137dae6ad8fSAl Viro 4138dae6ad8fSAl Viro error = -EXDEV; 4139dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4140dae6ad8fSAl Viro goto out_dput; 4141800179c9SKees Cook error = may_linkat(&old_path); 4142800179c9SKees Cook if (unlikely(error)) 4143800179c9SKees Cook goto out_dput; 4144dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4145be6d3e56SKentaro Takeda if (error) 4146a8104a9fSAl Viro goto out_dput; 4147146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 414875c3f29dSDave Hansen out_dput: 4149921a1650SAl Viro done_path_create(&new_path, new_dentry); 4150146a8595SJ. Bruce Fields if (delegated_inode) { 4151146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4152d22e6338SOleg Drokin if (!error) { 4153d22e6338SOleg Drokin path_put(&old_path); 4154146a8595SJ. Bruce Fields goto retry; 4155146a8595SJ. Bruce Fields } 4156d22e6338SOleg Drokin } 4157442e31caSJeff Layton if (retry_estale(error, how)) { 4158d22e6338SOleg Drokin path_put(&old_path); 4159442e31caSJeff Layton how |= LOOKUP_REVAL; 4160442e31caSJeff Layton goto retry; 4161442e31caSJeff Layton } 41621da177e4SLinus Torvalds out: 41632d8f3038SAl Viro path_put(&old_path); 41641da177e4SLinus Torvalds 41651da177e4SLinus Torvalds return error; 41661da177e4SLinus Torvalds } 41671da177e4SLinus Torvalds 41683480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 41695590ff0dSUlrich Drepper { 4170c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 41715590ff0dSUlrich Drepper } 41725590ff0dSUlrich Drepper 4173bc27027aSMiklos Szeredi /** 4174bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4175bc27027aSMiklos Szeredi * @old_dir: parent of source 4176bc27027aSMiklos Szeredi * @old_dentry: source 4177bc27027aSMiklos Szeredi * @new_dir: parent of destination 4178bc27027aSMiklos Szeredi * @new_dentry: destination 4179bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4180520c8b16SMiklos Szeredi * @flags: rename flags 4181bc27027aSMiklos Szeredi * 4182bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4183bc27027aSMiklos Szeredi * 4184bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4185bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4186bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4187bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4188bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4189bc27027aSMiklos Szeredi * so. 4190bc27027aSMiklos Szeredi * 4191bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4192bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4193bc27027aSMiklos Szeredi * to be NFS exported. 4194bc27027aSMiklos Szeredi * 41951da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 41961da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 41971da177e4SLinus Torvalds * Problems: 4198d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 41991da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 42001da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4201a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 42021da177e4SLinus Torvalds * story. 42036cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 42046cedba89SJ. Bruce Fields * and source (if it is not a directory). 42051b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 42061da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 42071da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4208a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 42091da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 42101da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 42111da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4212a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 42131da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 42141da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 42151da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4216e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 42171b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 42181da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4219c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 42201da177e4SLinus Torvalds * locking]. 42211da177e4SLinus Torvalds */ 42221da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 42238e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4224520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 42251da177e4SLinus Torvalds { 42261da177e4SLinus Torvalds int error; 4227bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 422859b0df21SEric Paris const unsigned char *old_name; 4229bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4230bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4231da1ce067SMiklos Szeredi bool new_is_dir = false; 4232da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 42331da177e4SLinus Torvalds 4234bc27027aSMiklos Szeredi if (source == target) 42351da177e4SLinus Torvalds return 0; 42361da177e4SLinus Torvalds 42371da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 42381da177e4SLinus Torvalds if (error) 42391da177e4SLinus Torvalds return error; 42401da177e4SLinus Torvalds 4241da1ce067SMiklos Szeredi if (!target) { 4242a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4243da1ce067SMiklos Szeredi } else { 4244da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4245da1ce067SMiklos Szeredi 4246da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 42471da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4248da1ce067SMiklos Szeredi else 4249da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4250da1ce067SMiklos Szeredi } 42511da177e4SLinus Torvalds if (error) 42521da177e4SLinus Torvalds return error; 42531da177e4SLinus Torvalds 42547177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 42551da177e4SLinus Torvalds return -EPERM; 42561da177e4SLinus Torvalds 4257520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4258520c8b16SMiklos Szeredi return -EINVAL; 4259520c8b16SMiklos Szeredi 4260bc27027aSMiklos Szeredi /* 4261bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4262bc27027aSMiklos Szeredi * we'll need to flip '..'. 4263bc27027aSMiklos Szeredi */ 4264da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4265da1ce067SMiklos Szeredi if (is_dir) { 4266bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4267bc27027aSMiklos Szeredi if (error) 4268bc27027aSMiklos Szeredi return error; 4269bc27027aSMiklos Szeredi } 4270da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4271da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4272da1ce067SMiklos Szeredi if (error) 4273da1ce067SMiklos Szeredi return error; 4274da1ce067SMiklos Szeredi } 4275da1ce067SMiklos Szeredi } 42760eeca283SRobert Love 42770b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 42780b3974ebSMiklos Szeredi flags); 4279bc27027aSMiklos Szeredi if (error) 4280bc27027aSMiklos Szeredi return error; 4281bc27027aSMiklos Szeredi 4282bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4283bc27027aSMiklos Szeredi dget(new_dentry); 4284da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4285bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4286bc27027aSMiklos Szeredi else if (target) 4287bc27027aSMiklos Szeredi mutex_lock(&target->i_mutex); 4288bc27027aSMiklos Szeredi 4289bc27027aSMiklos Szeredi error = -EBUSY; 42907af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4291bc27027aSMiklos Szeredi goto out; 4292bc27027aSMiklos Szeredi 4293da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4294bc27027aSMiklos Szeredi error = -EMLINK; 4295da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4296bc27027aSMiklos Szeredi goto out; 4297da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4298da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4299da1ce067SMiklos Szeredi goto out; 4300da1ce067SMiklos Szeredi } 4301da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4302bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4303da1ce067SMiklos Szeredi if (!is_dir) { 4304bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4305bc27027aSMiklos Szeredi if (error) 4306bc27027aSMiklos Szeredi goto out; 4307da1ce067SMiklos Szeredi } 4308da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4309bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4310bc27027aSMiklos Szeredi if (error) 4311bc27027aSMiklos Szeredi goto out; 4312bc27027aSMiklos Szeredi } 43137177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4314520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4315520c8b16SMiklos Szeredi new_dir, new_dentry); 4316520c8b16SMiklos Szeredi } else { 43177177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4318520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4319520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4320520c8b16SMiklos Szeredi } 4321bc27027aSMiklos Szeredi if (error) 4322bc27027aSMiklos Szeredi goto out; 4323bc27027aSMiklos Szeredi 4324da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 43251da177e4SLinus Torvalds if (is_dir) 4326bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4327bc27027aSMiklos Szeredi dont_mount(new_dentry); 43288ed936b5SEric W. Biederman detach_mounts(new_dentry); 4329bc27027aSMiklos Szeredi } 4330da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4331da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4332bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4333da1ce067SMiklos Szeredi else 4334da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4335da1ce067SMiklos Szeredi } 4336bc27027aSMiklos Szeredi out: 4337da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4338bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4339bc27027aSMiklos Szeredi else if (target) 4340bc27027aSMiklos Szeredi mutex_unlock(&target->i_mutex); 4341bc27027aSMiklos Szeredi dput(new_dentry); 4342da1ce067SMiklos Szeredi if (!error) { 4343123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4344da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4345da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4346da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4347da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4348da1ce067SMiklos Szeredi } 4349da1ce067SMiklos Szeredi } 43500eeca283SRobert Love fsnotify_oldname_free(old_name); 43510eeca283SRobert Love 43521da177e4SLinus Torvalds return error; 43531da177e4SLinus Torvalds } 43544d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 43551da177e4SLinus Torvalds 4356520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4357520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 43581da177e4SLinus Torvalds { 43591da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 43601da177e4SLinus Torvalds struct dentry *trap; 4361f5beed75SAl Viro struct path old_path, new_path; 4362f5beed75SAl Viro struct qstr old_last, new_last; 4363f5beed75SAl Viro int old_type, new_type; 43648e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 436591a27b2aSJeff Layton struct filename *from; 436691a27b2aSJeff Layton struct filename *to; 4367f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4368c6a94284SJeff Layton bool should_retry = false; 43692ad94ae6SAl Viro int error; 4370520c8b16SMiklos Szeredi 43710d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4372da1ce067SMiklos Szeredi return -EINVAL; 4373da1ce067SMiklos Szeredi 43740d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 43750d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4376520c8b16SMiklos Szeredi return -EINVAL; 4377520c8b16SMiklos Szeredi 43780d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 43790d7a8555SMiklos Szeredi return -EPERM; 43800d7a8555SMiklos Szeredi 4381f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4382f5beed75SAl Viro target_flags = 0; 4383f5beed75SAl Viro 4384c6a94284SJeff Layton retry: 4385f5beed75SAl Viro from = user_path_parent(olddfd, oldname, 4386f5beed75SAl Viro &old_path, &old_last, &old_type, lookup_flags); 438791a27b2aSJeff Layton if (IS_ERR(from)) { 438891a27b2aSJeff Layton error = PTR_ERR(from); 43891da177e4SLinus Torvalds goto exit; 439091a27b2aSJeff Layton } 43911da177e4SLinus Torvalds 4392f5beed75SAl Viro to = user_path_parent(newdfd, newname, 4393f5beed75SAl Viro &new_path, &new_last, &new_type, lookup_flags); 439491a27b2aSJeff Layton if (IS_ERR(to)) { 439591a27b2aSJeff Layton error = PTR_ERR(to); 43961da177e4SLinus Torvalds goto exit1; 439791a27b2aSJeff Layton } 43981da177e4SLinus Torvalds 43991da177e4SLinus Torvalds error = -EXDEV; 4400f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 44011da177e4SLinus Torvalds goto exit2; 44021da177e4SLinus Torvalds 44031da177e4SLinus Torvalds error = -EBUSY; 4404f5beed75SAl Viro if (old_type != LAST_NORM) 44051da177e4SLinus Torvalds goto exit2; 44061da177e4SLinus Torvalds 44070a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 44080a7c3937SMiklos Szeredi error = -EEXIST; 4409f5beed75SAl Viro if (new_type != LAST_NORM) 44101da177e4SLinus Torvalds goto exit2; 44111da177e4SLinus Torvalds 4412f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4413c30dabfeSJan Kara if (error) 4414c30dabfeSJan Kara goto exit2; 4415c30dabfeSJan Kara 44168e6d782cSJ. Bruce Fields retry_deleg: 4417f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 44181da177e4SLinus Torvalds 4419f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 44201da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 44211da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 44221da177e4SLinus Torvalds goto exit3; 44231da177e4SLinus Torvalds /* source must exist */ 44241da177e4SLinus Torvalds error = -ENOENT; 4425b18825a7SDavid Howells if (d_is_negative(old_dentry)) 44261da177e4SLinus Torvalds goto exit4; 4427f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 44281da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 44291da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 44301da177e4SLinus Torvalds goto exit4; 44310a7c3937SMiklos Szeredi error = -EEXIST; 44320a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 44330a7c3937SMiklos Szeredi goto exit5; 4434da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4435da1ce067SMiklos Szeredi error = -ENOENT; 4436da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4437da1ce067SMiklos Szeredi goto exit5; 4438da1ce067SMiklos Szeredi 4439da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4440da1ce067SMiklos Szeredi error = -ENOTDIR; 4441f5beed75SAl Viro if (new_last.name[new_last.len]) 4442da1ce067SMiklos Szeredi goto exit5; 4443da1ce067SMiklos Szeredi } 4444da1ce067SMiklos Szeredi } 44450a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 44460a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 44470a7c3937SMiklos Szeredi error = -ENOTDIR; 4448f5beed75SAl Viro if (old_last.name[old_last.len]) 44490a7c3937SMiklos Szeredi goto exit5; 4450f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 44510a7c3937SMiklos Szeredi goto exit5; 44520a7c3937SMiklos Szeredi } 44530a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 44540a7c3937SMiklos Szeredi error = -EINVAL; 44550a7c3937SMiklos Szeredi if (old_dentry == trap) 44560a7c3937SMiklos Szeredi goto exit5; 44571da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4458da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 44591da177e4SLinus Torvalds error = -ENOTEMPTY; 44601da177e4SLinus Torvalds if (new_dentry == trap) 44611da177e4SLinus Torvalds goto exit5; 44621da177e4SLinus Torvalds 4463f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4464f5beed75SAl Viro &new_path, new_dentry, flags); 4465be6d3e56SKentaro Takeda if (error) 4466c30dabfeSJan Kara goto exit5; 4467f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4468f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4469520c8b16SMiklos Szeredi &delegated_inode, flags); 44701da177e4SLinus Torvalds exit5: 44711da177e4SLinus Torvalds dput(new_dentry); 44721da177e4SLinus Torvalds exit4: 44731da177e4SLinus Torvalds dput(old_dentry); 44741da177e4SLinus Torvalds exit3: 4475f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 44768e6d782cSJ. Bruce Fields if (delegated_inode) { 44778e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 44788e6d782cSJ. Bruce Fields if (!error) 44798e6d782cSJ. Bruce Fields goto retry_deleg; 44808e6d782cSJ. Bruce Fields } 4481f5beed75SAl Viro mnt_drop_write(old_path.mnt); 44821da177e4SLinus Torvalds exit2: 4483c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4484c6a94284SJeff Layton should_retry = true; 4485f5beed75SAl Viro path_put(&new_path); 44862ad94ae6SAl Viro putname(to); 44871da177e4SLinus Torvalds exit1: 4488f5beed75SAl Viro path_put(&old_path); 44891da177e4SLinus Torvalds putname(from); 4490c6a94284SJeff Layton if (should_retry) { 4491c6a94284SJeff Layton should_retry = false; 4492c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4493c6a94284SJeff Layton goto retry; 4494c6a94284SJeff Layton } 44952ad94ae6SAl Viro exit: 44961da177e4SLinus Torvalds return error; 44971da177e4SLinus Torvalds } 44981da177e4SLinus Torvalds 4499520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4500520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4501520c8b16SMiklos Szeredi { 4502520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4503520c8b16SMiklos Szeredi } 4504520c8b16SMiklos Szeredi 4505a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 45065590ff0dSUlrich Drepper { 4507520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 45085590ff0dSUlrich Drepper } 45095590ff0dSUlrich Drepper 4510787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4511787fb6bcSMiklos Szeredi { 4512787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4513787fb6bcSMiklos Szeredi if (error) 4514787fb6bcSMiklos Szeredi return error; 4515787fb6bcSMiklos Szeredi 4516787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4517787fb6bcSMiklos Szeredi return -EPERM; 4518787fb6bcSMiklos Szeredi 4519787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4520787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4521787fb6bcSMiklos Szeredi } 4522787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4523787fb6bcSMiklos Szeredi 45245d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 45251da177e4SLinus Torvalds { 45265d826c84SAl Viro int len = PTR_ERR(link); 45271da177e4SLinus Torvalds if (IS_ERR(link)) 45281da177e4SLinus Torvalds goto out; 45291da177e4SLinus Torvalds 45301da177e4SLinus Torvalds len = strlen(link); 45311da177e4SLinus Torvalds if (len > (unsigned) buflen) 45321da177e4SLinus Torvalds len = buflen; 45331da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 45341da177e4SLinus Torvalds len = -EFAULT; 45351da177e4SLinus Torvalds out: 45361da177e4SLinus Torvalds return len; 45371da177e4SLinus Torvalds } 45385d826c84SAl Viro EXPORT_SYMBOL(readlink_copy); 45391da177e4SLinus Torvalds 45401da177e4SLinus Torvalds /* 45411da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 45421da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 45431da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 45441da177e4SLinus Torvalds */ 45451da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 45461da177e4SLinus Torvalds { 4547cc314eefSLinus Torvalds void *cookie; 45485f2c4179SAl Viro struct inode *inode = d_inode(dentry); 45495f2c4179SAl Viro const char *link = inode->i_link; 4550694a1764SMarcin Slusarz int res; 4551cc314eefSLinus Torvalds 4552d4dee48bSAl Viro if (!link) { 45535f2c4179SAl Viro link = inode->i_op->follow_link(dentry, &cookie); 4554680baacbSAl Viro if (IS_ERR(link)) 4555680baacbSAl Viro return PTR_ERR(link); 4556d4dee48bSAl Viro } 4557680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 45585f2c4179SAl Viro if (inode->i_op->put_link) 45595f2c4179SAl Viro inode->i_op->put_link(inode, cookie); 4560694a1764SMarcin Slusarz return res; 45611da177e4SLinus Torvalds } 45624d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 45631da177e4SLinus Torvalds 45641da177e4SLinus Torvalds /* get the link contents into pagecache */ 45651da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 45661da177e4SLinus Torvalds { 4567ebd09abbSDuane Griffin char *kaddr; 45681da177e4SLinus Torvalds struct page *page; 45691da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 4570090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 45711da177e4SLinus Torvalds if (IS_ERR(page)) 45726fe6900eSNick Piggin return (char*)page; 45731da177e4SLinus Torvalds *ppage = page; 4574ebd09abbSDuane Griffin kaddr = kmap(page); 4575ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 4576ebd09abbSDuane Griffin return kaddr; 45771da177e4SLinus Torvalds } 45781da177e4SLinus Torvalds 45791da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 45801da177e4SLinus Torvalds { 45811da177e4SLinus Torvalds struct page *page = NULL; 45825d826c84SAl Viro int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); 45831da177e4SLinus Torvalds if (page) { 45841da177e4SLinus Torvalds kunmap(page); 45851da177e4SLinus Torvalds page_cache_release(page); 45861da177e4SLinus Torvalds } 45871da177e4SLinus Torvalds return res; 45881da177e4SLinus Torvalds } 45894d359507SAl Viro EXPORT_SYMBOL(page_readlink); 45901da177e4SLinus Torvalds 45916e77137bSAl Viro const char *page_follow_link_light(struct dentry *dentry, void **cookie) 45921da177e4SLinus Torvalds { 4593cc314eefSLinus Torvalds struct page *page = NULL; 4594680baacbSAl Viro char *res = page_getlink(dentry, &page); 4595680baacbSAl Viro if (!IS_ERR(res)) 4596680baacbSAl Viro *cookie = page; 4597680baacbSAl Viro return res; 45981da177e4SLinus Torvalds } 45994d359507SAl Viro EXPORT_SYMBOL(page_follow_link_light); 46001da177e4SLinus Torvalds 46015f2c4179SAl Viro void page_put_link(struct inode *unused, void *cookie) 46021da177e4SLinus Torvalds { 4603cc314eefSLinus Torvalds struct page *page = cookie; 46041da177e4SLinus Torvalds kunmap(page); 46051da177e4SLinus Torvalds page_cache_release(page); 46061da177e4SLinus Torvalds } 46074d359507SAl Viro EXPORT_SYMBOL(page_put_link); 46081da177e4SLinus Torvalds 460954566b2cSNick Piggin /* 461054566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 461154566b2cSNick Piggin */ 461254566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 46131da177e4SLinus Torvalds { 46141da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 46150adb25d2SKirill Korotaev struct page *page; 4616afddba49SNick Piggin void *fsdata; 4617beb497abSDmitriy Monakhov int err; 46181da177e4SLinus Torvalds char *kaddr; 461954566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 462054566b2cSNick Piggin if (nofs) 462154566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 46221da177e4SLinus Torvalds 46237e53cac4SNeilBrown retry: 4624afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 462554566b2cSNick Piggin flags, &page, &fsdata); 46261da177e4SLinus Torvalds if (err) 4627afddba49SNick Piggin goto fail; 4628afddba49SNick Piggin 4629e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 46301da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 4631e8e3c3d6SCong Wang kunmap_atomic(kaddr); 4632afddba49SNick Piggin 4633afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4634afddba49SNick Piggin page, fsdata); 46351da177e4SLinus Torvalds if (err < 0) 46361da177e4SLinus Torvalds goto fail; 4637afddba49SNick Piggin if (err < len-1) 4638afddba49SNick Piggin goto retry; 4639afddba49SNick Piggin 46401da177e4SLinus Torvalds mark_inode_dirty(inode); 46411da177e4SLinus Torvalds return 0; 46421da177e4SLinus Torvalds fail: 46431da177e4SLinus Torvalds return err; 46441da177e4SLinus Torvalds } 46454d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 46461da177e4SLinus Torvalds 46470adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 46480adb25d2SKirill Korotaev { 46490adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 465054566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 46510adb25d2SKirill Korotaev } 46524d359507SAl Viro EXPORT_SYMBOL(page_symlink); 46530adb25d2SKirill Korotaev 465492e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 46551da177e4SLinus Torvalds .readlink = generic_readlink, 46561da177e4SLinus Torvalds .follow_link = page_follow_link_light, 46571da177e4SLinus Torvalds .put_link = page_put_link, 46581da177e4SLinus Torvalds }; 46591da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4660