11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namei.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Some corrections by tytso. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 121da177e4SLinus Torvalds * lookup logic. 131da177e4SLinus Torvalds */ 141da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 151da177e4SLinus Torvalds */ 161da177e4SLinus Torvalds 171da177e4SLinus Torvalds #include <linux/init.h> 18630d9c47SPaul Gortmaker #include <linux/export.h> 1944696908SDavid S. Miller #include <linux/kernel.h> 201da177e4SLinus Torvalds #include <linux/slab.h> 211da177e4SLinus Torvalds #include <linux/fs.h> 221da177e4SLinus Torvalds #include <linux/namei.h> 231da177e4SLinus Torvalds #include <linux/pagemap.h> 240eeca283SRobert Love #include <linux/fsnotify.h> 251da177e4SLinus Torvalds #include <linux/personality.h> 261da177e4SLinus Torvalds #include <linux/security.h> 276146f0d5SMimi Zohar #include <linux/ima.h> 281da177e4SLinus Torvalds #include <linux/syscalls.h> 291da177e4SLinus Torvalds #include <linux/mount.h> 301da177e4SLinus Torvalds #include <linux/audit.h> 3116f7e0feSRandy Dunlap #include <linux/capability.h> 32834f2a4aSTrond Myklebust #include <linux/file.h> 335590ff0dSUlrich Drepper #include <linux/fcntl.h> 3408ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 355ad4e53bSAl Viro #include <linux/fs_struct.h> 36e77819e5SLinus Torvalds #include <linux/posix_acl.h> 3799d263d4SLinus Torvalds #include <linux/hash.h> 381da177e4SLinus Torvalds #include <asm/uaccess.h> 391da177e4SLinus Torvalds 40e81e3f4dSEric Paris #include "internal.h" 41c7105365SAl Viro #include "mount.h" 42e81e3f4dSEric Paris 431da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 441da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 451da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 461da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 471da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 481da177e4SLinus Torvalds * 491da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 501da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 511da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 521da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 531da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 541da177e4SLinus Torvalds * the special cases of the former code. 551da177e4SLinus Torvalds * 561da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 571da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 581da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 591da177e4SLinus Torvalds * 601da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 611da177e4SLinus Torvalds * resolution to correspond with current state of the code. 621da177e4SLinus Torvalds * 631da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 641da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 651da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 661da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 671da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 681da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 691da177e4SLinus Torvalds */ 701da177e4SLinus Torvalds 711da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 721da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 731da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 741da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 751da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 761da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7725985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 781da177e4SLinus Torvalds * 791da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 801da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 811da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 821da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 831da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 841da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 851da177e4SLinus Torvalds * and in the old Linux semantics. 861da177e4SLinus Torvalds */ 871da177e4SLinus Torvalds 881da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 891da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 901da177e4SLinus Torvalds * 911da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 921da177e4SLinus Torvalds */ 931da177e4SLinus Torvalds 941da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 951da177e4SLinus Torvalds * inside the path - always follow. 961da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 971da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 981da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 991da177e4SLinus Torvalds * otherwise - don't follow. 1001da177e4SLinus Torvalds * (applied in that order). 1011da177e4SLinus Torvalds * 1021da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1031da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1041da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1051da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1061da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1071da177e4SLinus Torvalds */ 1081da177e4SLinus Torvalds /* 1091da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 110a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1111da177e4SLinus Torvalds * any extra contention... 1121da177e4SLinus Torvalds */ 1131da177e4SLinus Torvalds 1141da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1151da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1161da177e4SLinus Torvalds * kernel data space before using them.. 1171da177e4SLinus Torvalds * 1181da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1191da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1201da177e4SLinus Torvalds */ 1217950e385SJeff Layton 122fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12391a27b2aSJeff Layton 12451f39a1fSDavid Drysdale struct filename * 12591a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12691a27b2aSJeff Layton { 12794b5d262SAl Viro struct filename *result; 1287950e385SJeff Layton char *kname; 12994b5d262SAl Viro int len; 1301da177e4SLinus Torvalds 1317ac86265SJeff Layton result = audit_reusename(filename); 1327ac86265SJeff Layton if (result) 1337ac86265SJeff Layton return result; 1347ac86265SJeff Layton 1357950e385SJeff Layton result = __getname(); 1363f9f0aa6SLinus Torvalds if (unlikely(!result)) 1374043cde8SEric Paris return ERR_PTR(-ENOMEM); 1381da177e4SLinus Torvalds 1397950e385SJeff Layton /* 1407950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1417950e385SJeff Layton * allocation 1427950e385SJeff Layton */ 143fd2f7cb5SAl Viro kname = (char *)result->iname; 14491a27b2aSJeff Layton result->name = kname; 1457950e385SJeff Layton 14694b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 14791a27b2aSJeff Layton if (unlikely(len < 0)) { 14894b5d262SAl Viro __putname(result); 14994b5d262SAl Viro return ERR_PTR(len); 15091a27b2aSJeff Layton } 1513f9f0aa6SLinus Torvalds 1527950e385SJeff Layton /* 1537950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1547950e385SJeff Layton * separate struct filename so we can dedicate the entire 1557950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1567950e385SJeff Layton * userland. 1577950e385SJeff Layton */ 15894b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 159fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1607950e385SJeff Layton kname = (char *)result; 1617950e385SJeff Layton 162fd2f7cb5SAl Viro /* 163fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 164fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 165fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 166fd2f7cb5SAl Viro */ 167fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 16894b5d262SAl Viro if (unlikely(!result)) { 16994b5d262SAl Viro __putname(kname); 17094b5d262SAl Viro return ERR_PTR(-ENOMEM); 1717950e385SJeff Layton } 1727950e385SJeff Layton result->name = kname; 17394b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17494b5d262SAl Viro if (unlikely(len < 0)) { 17594b5d262SAl Viro __putname(kname); 17694b5d262SAl Viro kfree(result); 17794b5d262SAl Viro return ERR_PTR(len); 17894b5d262SAl Viro } 17994b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18094b5d262SAl Viro __putname(kname); 18194b5d262SAl Viro kfree(result); 18294b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18394b5d262SAl Viro } 1847950e385SJeff Layton } 1857950e385SJeff Layton 18694b5d262SAl Viro result->refcnt = 1; 1873f9f0aa6SLinus Torvalds /* The empty path is special. */ 1883f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1893f9f0aa6SLinus Torvalds if (empty) 1901fa1e7f6SAndy Whitcroft *empty = 1; 19194b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19294b5d262SAl Viro putname(result); 19394b5d262SAl Viro return ERR_PTR(-ENOENT); 1941da177e4SLinus Torvalds } 19594b5d262SAl Viro } 1967950e385SJeff Layton 1977950e385SJeff Layton result->uptr = filename; 198c4ad8f98SLinus Torvalds result->aname = NULL; 1991da177e4SLinus Torvalds audit_getname(result); 2001da177e4SLinus Torvalds return result; 2013f9f0aa6SLinus Torvalds } 2023f9f0aa6SLinus Torvalds 20391a27b2aSJeff Layton struct filename * 20491a27b2aSJeff Layton getname(const char __user * filename) 205f52e0c11SAl Viro { 206f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 207f52e0c11SAl Viro } 208f52e0c11SAl Viro 209c4ad8f98SLinus Torvalds struct filename * 210c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 211c4ad8f98SLinus Torvalds { 212c4ad8f98SLinus Torvalds struct filename *result; 21308518549SPaul Moore int len = strlen(filename) + 1; 214c4ad8f98SLinus Torvalds 215c4ad8f98SLinus Torvalds result = __getname(); 216c4ad8f98SLinus Torvalds if (unlikely(!result)) 217c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 218c4ad8f98SLinus Torvalds 21908518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 220fd2f7cb5SAl Viro result->name = (char *)result->iname; 22108518549SPaul Moore } else if (len <= PATH_MAX) { 22208518549SPaul Moore struct filename *tmp; 22308518549SPaul Moore 22408518549SPaul Moore tmp = kmalloc(sizeof(*tmp), GFP_KERNEL); 22508518549SPaul Moore if (unlikely(!tmp)) { 22608518549SPaul Moore __putname(result); 22708518549SPaul Moore return ERR_PTR(-ENOMEM); 22808518549SPaul Moore } 22908518549SPaul Moore tmp->name = (char *)result; 23008518549SPaul Moore result = tmp; 23108518549SPaul Moore } else { 23208518549SPaul Moore __putname(result); 23308518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23408518549SPaul Moore } 23508518549SPaul Moore memcpy((char *)result->name, filename, len); 236c4ad8f98SLinus Torvalds result->uptr = NULL; 237c4ad8f98SLinus Torvalds result->aname = NULL; 23855422d0bSPaul Moore result->refcnt = 1; 239fd3522fdSPaul Moore audit_getname(result); 240c4ad8f98SLinus Torvalds 241c4ad8f98SLinus Torvalds return result; 242c4ad8f98SLinus Torvalds } 243c4ad8f98SLinus Torvalds 24491a27b2aSJeff Layton void putname(struct filename *name) 2451da177e4SLinus Torvalds { 24655422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 24755422d0bSPaul Moore 24855422d0bSPaul Moore if (--name->refcnt > 0) 24955422d0bSPaul Moore return; 25055422d0bSPaul Moore 251fd2f7cb5SAl Viro if (name->name != name->iname) { 25255422d0bSPaul Moore __putname(name->name); 25355422d0bSPaul Moore kfree(name); 25455422d0bSPaul Moore } else 25555422d0bSPaul Moore __putname(name); 2561da177e4SLinus Torvalds } 2571da177e4SLinus Torvalds 258e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 259e77819e5SLinus Torvalds { 26084635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 261e77819e5SLinus Torvalds struct posix_acl *acl; 262e77819e5SLinus Torvalds 263e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2643567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2653567866bSAl Viro if (!acl) 266e77819e5SLinus Torvalds return -EAGAIN; 2673567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 2683567866bSAl Viro if (acl == ACL_NOT_CACHED) 269e77819e5SLinus Torvalds return -ECHILD; 270206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 271e77819e5SLinus Torvalds } 272e77819e5SLinus Torvalds 2732982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2744e34e719SChristoph Hellwig if (IS_ERR(acl)) 2754e34e719SChristoph Hellwig return PTR_ERR(acl); 276e77819e5SLinus Torvalds if (acl) { 277e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 278e77819e5SLinus Torvalds posix_acl_release(acl); 279e77819e5SLinus Torvalds return error; 280e77819e5SLinus Torvalds } 28184635d68SLinus Torvalds #endif 282e77819e5SLinus Torvalds 283e77819e5SLinus Torvalds return -EAGAIN; 284e77819e5SLinus Torvalds } 285e77819e5SLinus Torvalds 2865909ccaaSLinus Torvalds /* 287948409c7SAndreas Gruenbacher * This does the basic permission checking 2885909ccaaSLinus Torvalds */ 2897e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2905909ccaaSLinus Torvalds { 29126cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2925909ccaaSLinus Torvalds 2938e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2945909ccaaSLinus Torvalds mode >>= 6; 2955909ccaaSLinus Torvalds else { 296e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2977e40145eSAl Viro int error = check_acl(inode, mask); 2985909ccaaSLinus Torvalds if (error != -EAGAIN) 2995909ccaaSLinus Torvalds return error; 3005909ccaaSLinus Torvalds } 3015909ccaaSLinus Torvalds 3025909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3035909ccaaSLinus Torvalds mode >>= 3; 3045909ccaaSLinus Torvalds } 3055909ccaaSLinus Torvalds 3065909ccaaSLinus Torvalds /* 3075909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3085909ccaaSLinus Torvalds */ 3099c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3105909ccaaSLinus Torvalds return 0; 3115909ccaaSLinus Torvalds return -EACCES; 3125909ccaaSLinus Torvalds } 3131da177e4SLinus Torvalds 3141da177e4SLinus Torvalds /** 3151da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3161da177e4SLinus Torvalds * @inode: inode to check access rights for 3178fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3181da177e4SLinus Torvalds * 3191da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3201da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3211da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 322b74c79e9SNick Piggin * are used for other things. 323b74c79e9SNick Piggin * 324b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 325b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 326b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3271da177e4SLinus Torvalds */ 3282830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3291da177e4SLinus Torvalds { 3305909ccaaSLinus Torvalds int ret; 3311da177e4SLinus Torvalds 3321da177e4SLinus Torvalds /* 333948409c7SAndreas Gruenbacher * Do the basic permission checks. 3341da177e4SLinus Torvalds */ 3357e40145eSAl Viro ret = acl_permission_check(inode, mask); 3365909ccaaSLinus Torvalds if (ret != -EACCES) 3375909ccaaSLinus Torvalds return ret; 3381da177e4SLinus Torvalds 339d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 340d594e7ecSAl Viro /* DACs are overridable for directories */ 34123adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 342d594e7ecSAl Viro return 0; 343d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34423adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34523adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 346d594e7ecSAl Viro return 0; 347d594e7ecSAl Viro return -EACCES; 348d594e7ecSAl Viro } 3491da177e4SLinus Torvalds /* 3501da177e4SLinus Torvalds * Read/write DACs are always overridable. 351d594e7ecSAl Viro * Executable DACs are overridable when there is 352d594e7ecSAl Viro * at least one exec bit set. 3531da177e4SLinus Torvalds */ 354d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 35523adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3561da177e4SLinus Torvalds return 0; 3571da177e4SLinus Torvalds 3581da177e4SLinus Torvalds /* 3591da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3601da177e4SLinus Torvalds */ 3617ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 362d594e7ecSAl Viro if (mask == MAY_READ) 36323adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3641da177e4SLinus Torvalds return 0; 3651da177e4SLinus Torvalds 3661da177e4SLinus Torvalds return -EACCES; 3671da177e4SLinus Torvalds } 3684d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3691da177e4SLinus Torvalds 3703ddcd056SLinus Torvalds /* 3713ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3723ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3733ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3743ddcd056SLinus Torvalds * permission function, use the fast case". 3753ddcd056SLinus Torvalds */ 3763ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3773ddcd056SLinus Torvalds { 3783ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3793ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3803ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3813ddcd056SLinus Torvalds 3823ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3833ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3843ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3853ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3863ddcd056SLinus Torvalds } 3873ddcd056SLinus Torvalds return generic_permission(inode, mask); 3883ddcd056SLinus Torvalds } 3893ddcd056SLinus Torvalds 390cb23beb5SChristoph Hellwig /** 3910bdaea90SDavid Howells * __inode_permission - Check for access rights to a given inode 3920bdaea90SDavid Howells * @inode: Inode to check permission on 3930bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 394cb23beb5SChristoph Hellwig * 3950bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. 396948409c7SAndreas Gruenbacher * 397948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 3980bdaea90SDavid Howells * 3990bdaea90SDavid Howells * This does not check for a read-only file system. You probably want 4000bdaea90SDavid Howells * inode_permission(). 401cb23beb5SChristoph Hellwig */ 4020bdaea90SDavid Howells int __inode_permission(struct inode *inode, int mask) 4031da177e4SLinus Torvalds { 404e6305c43SAl Viro int retval; 4051da177e4SLinus Torvalds 4063ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 4071da177e4SLinus Torvalds /* 4081da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 4091da177e4SLinus Torvalds */ 4101da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 4111da177e4SLinus Torvalds return -EACCES; 4121da177e4SLinus Torvalds } 4131da177e4SLinus Torvalds 4143ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 4151da177e4SLinus Torvalds if (retval) 4161da177e4SLinus Torvalds return retval; 4171da177e4SLinus Torvalds 41808ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 41908ce5f16SSerge E. Hallyn if (retval) 42008ce5f16SSerge E. Hallyn return retval; 42108ce5f16SSerge E. Hallyn 422d09ca739SEric Paris return security_inode_permission(inode, mask); 4231da177e4SLinus Torvalds } 424bd5d0856SMiklos Szeredi EXPORT_SYMBOL(__inode_permission); 4251da177e4SLinus Torvalds 426f4d6ff89SAl Viro /** 4270bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 4280bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 42955852635SRandy Dunlap * @inode: Inode to check permission on 4300bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4310bdaea90SDavid Howells * 4320bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4330bdaea90SDavid Howells */ 4340bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4350bdaea90SDavid Howells { 4360bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4370bdaea90SDavid Howells umode_t mode = inode->i_mode; 4380bdaea90SDavid Howells 4390bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 4400bdaea90SDavid Howells if ((sb->s_flags & MS_RDONLY) && 4410bdaea90SDavid Howells (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4420bdaea90SDavid Howells return -EROFS; 4430bdaea90SDavid Howells } 4440bdaea90SDavid Howells return 0; 4450bdaea90SDavid Howells } 4460bdaea90SDavid Howells 4470bdaea90SDavid Howells /** 4480bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4490bdaea90SDavid Howells * @inode: Inode to check permission on 4500bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4510bdaea90SDavid Howells * 4520bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4530bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4540bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4550bdaea90SDavid Howells * 4560bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4570bdaea90SDavid Howells */ 4580bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4590bdaea90SDavid Howells { 4600bdaea90SDavid Howells int retval; 4610bdaea90SDavid Howells 4620bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4630bdaea90SDavid Howells if (retval) 4640bdaea90SDavid Howells return retval; 4650bdaea90SDavid Howells return __inode_permission(inode, mask); 4660bdaea90SDavid Howells } 4674d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4680bdaea90SDavid Howells 4690bdaea90SDavid Howells /** 4705dd784d0SJan Blunck * path_get - get a reference to a path 4715dd784d0SJan Blunck * @path: path to get the reference to 4725dd784d0SJan Blunck * 4735dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4745dd784d0SJan Blunck */ 475dcf787f3SAl Viro void path_get(const struct path *path) 4765dd784d0SJan Blunck { 4775dd784d0SJan Blunck mntget(path->mnt); 4785dd784d0SJan Blunck dget(path->dentry); 4795dd784d0SJan Blunck } 4805dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4815dd784d0SJan Blunck 4825dd784d0SJan Blunck /** 4831d957f9bSJan Blunck * path_put - put a reference to a path 4841d957f9bSJan Blunck * @path: path to put the reference to 4851d957f9bSJan Blunck * 4861d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4871d957f9bSJan Blunck */ 488dcf787f3SAl Viro void path_put(const struct path *path) 4891da177e4SLinus Torvalds { 4901d957f9bSJan Blunck dput(path->dentry); 4911d957f9bSJan Blunck mntput(path->mnt); 4921da177e4SLinus Torvalds } 4931d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4941da177e4SLinus Torvalds 4951f55a6ecSAl Viro struct nameidata { 4961f55a6ecSAl Viro struct path path; 497caa85634SAl Viro union { 4981f55a6ecSAl Viro struct qstr last; 499caa85634SAl Viro struct path link; 500caa85634SAl Viro }; 5011f55a6ecSAl Viro struct path root; 5021f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 5031f55a6ecSAl Viro unsigned int flags; 5041f55a6ecSAl Viro unsigned seq, m_seq; 5051f55a6ecSAl Viro int last_type; 5061f55a6ecSAl Viro unsigned depth; 5075e53084dSAl Viro struct file *base; 5081f55a6ecSAl Viro }; 5091f55a6ecSAl Viro 51019660af7SAl Viro /* 51131e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 51219660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 51319660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 51419660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 51519660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 51619660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 51719660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 51819660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 51931e6b01fSNick Piggin */ 52031e6b01fSNick Piggin 52131e6b01fSNick Piggin /** 52219660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 52319660af7SAl Viro * @nd: nameidata pathwalk data 52419660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 52539191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 52631e6b01fSNick Piggin * 52719660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 52819660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 52919660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 53031e6b01fSNick Piggin */ 53119660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 53231e6b01fSNick Piggin { 53331e6b01fSNick Piggin struct fs_struct *fs = current->fs; 53431e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 53531e6b01fSNick Piggin 53631e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 537e5c832d5SLinus Torvalds 538e5c832d5SLinus Torvalds /* 53948a066e7SAl Viro * After legitimizing the bastards, terminate_walk() 54048a066e7SAl Viro * will do the right thing for non-RCU mode, and all our 54148a066e7SAl Viro * subsequent exit cases should rcu_read_unlock() 54248a066e7SAl Viro * before returning. Do vfsmount first; if dentry 54348a066e7SAl Viro * can't be legitimized, just set nd->path.dentry to NULL 54448a066e7SAl Viro * and rely on dput(NULL) being a no-op. 545e5c832d5SLinus Torvalds */ 54648a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) 547e5c832d5SLinus Torvalds return -ECHILD; 548e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 54915570086SLinus Torvalds 55048a066e7SAl Viro if (!lockref_get_not_dead(&parent->d_lockref)) { 55148a066e7SAl Viro nd->path.dentry = NULL; 552d870b4a1SAl Viro goto out; 55348a066e7SAl Viro } 55448a066e7SAl Viro 55515570086SLinus Torvalds /* 55615570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 55715570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 55815570086SLinus Torvalds * 55915570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 56015570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 56115570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 56215570086SLinus Torvalds * since we checked the sequence number of the parent after we got 56315570086SLinus Torvalds * the child sequence number. So we know the parent must still 56415570086SLinus Torvalds * be valid if the child sequence number is still valid. 56515570086SLinus Torvalds */ 56619660af7SAl Viro if (!dentry) { 567e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 568e5c832d5SLinus Torvalds goto out; 56919660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 57019660af7SAl Viro } else { 571e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 572e5c832d5SLinus Torvalds goto out; 573e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) 574e5c832d5SLinus Torvalds goto drop_dentry; 57519660af7SAl Viro } 576e5c832d5SLinus Torvalds 577e5c832d5SLinus Torvalds /* 578e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 579e5c832d5SLinus Torvalds * still valid and get it if required. 580e5c832d5SLinus Torvalds */ 581e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 582e5c832d5SLinus Torvalds spin_lock(&fs->lock); 583e5c832d5SLinus Torvalds if (nd->root.mnt != fs->root.mnt || nd->root.dentry != fs->root.dentry) 584e5c832d5SLinus Torvalds goto unlock_and_drop_dentry; 58531e6b01fSNick Piggin path_get(&nd->root); 58631e6b01fSNick Piggin spin_unlock(&fs->lock); 58731e6b01fSNick Piggin } 58831e6b01fSNick Piggin 5898b61e74fSAl Viro rcu_read_unlock(); 59031e6b01fSNick Piggin return 0; 59119660af7SAl Viro 592e5c832d5SLinus Torvalds unlock_and_drop_dentry: 59331e6b01fSNick Piggin spin_unlock(&fs->lock); 594e5c832d5SLinus Torvalds drop_dentry: 5958b61e74fSAl Viro rcu_read_unlock(); 596e5c832d5SLinus Torvalds dput(dentry); 597d0d27277SLinus Torvalds goto drop_root_mnt; 598e5c832d5SLinus Torvalds out: 5998b61e74fSAl Viro rcu_read_unlock(); 600d0d27277SLinus Torvalds drop_root_mnt: 601d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 602d0d27277SLinus Torvalds nd->root.mnt = NULL; 60331e6b01fSNick Piggin return -ECHILD; 60431e6b01fSNick Piggin } 60531e6b01fSNick Piggin 6064ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 60734286d66SNick Piggin { 6084ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 60934286d66SNick Piggin } 61034286d66SNick Piggin 6119f1fafeeSAl Viro /** 6129f1fafeeSAl Viro * complete_walk - successful completion of path walk 6139f1fafeeSAl Viro * @nd: pointer nameidata 61439159de2SJeff Layton * 6159f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 6169f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 6179f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 6189f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 6199f1fafeeSAl Viro * need to drop nd->path. 62039159de2SJeff Layton */ 6219f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 62239159de2SJeff Layton { 62316c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 62439159de2SJeff Layton int status; 62539159de2SJeff Layton 6269f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 6279f1fafeeSAl Viro nd->flags &= ~LOOKUP_RCU; 6289f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6299f1fafeeSAl Viro nd->root.mnt = NULL; 63015570086SLinus Torvalds 63148a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) { 6328b61e74fSAl Viro rcu_read_unlock(); 63348a066e7SAl Viro return -ECHILD; 63448a066e7SAl Viro } 635e5c832d5SLinus Torvalds if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) { 6368b61e74fSAl Viro rcu_read_unlock(); 63748a066e7SAl Viro mntput(nd->path.mnt); 6389f1fafeeSAl Viro return -ECHILD; 6399f1fafeeSAl Viro } 640e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) { 6418b61e74fSAl Viro rcu_read_unlock(); 642e5c832d5SLinus Torvalds dput(dentry); 64348a066e7SAl Viro mntput(nd->path.mnt); 644e5c832d5SLinus Torvalds return -ECHILD; 645e5c832d5SLinus Torvalds } 6468b61e74fSAl Viro rcu_read_unlock(); 6479f1fafeeSAl Viro } 6489f1fafeeSAl Viro 64916c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 65039159de2SJeff Layton return 0; 65139159de2SJeff Layton 652ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 65316c2cd71SAl Viro return 0; 65416c2cd71SAl Viro 655ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 65639159de2SJeff Layton if (status > 0) 65739159de2SJeff Layton return 0; 65839159de2SJeff Layton 65916c2cd71SAl Viro if (!status) 66039159de2SJeff Layton status = -ESTALE; 66116c2cd71SAl Viro 6629f1fafeeSAl Viro path_put(&nd->path); 66339159de2SJeff Layton return status; 66439159de2SJeff Layton } 66539159de2SJeff Layton 6662a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 6672a737871SAl Viro { 668f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 6692a737871SAl Viro } 6702a737871SAl Viro 6717bd88377SAl Viro static __always_inline unsigned set_root_rcu(struct nameidata *nd) 67231e6b01fSNick Piggin { 67331e6b01fSNick Piggin struct fs_struct *fs = current->fs; 6747bd88377SAl Viro unsigned seq, res; 675c28cc364SNick Piggin 676c28cc364SNick Piggin do { 677c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 67831e6b01fSNick Piggin nd->root = fs->root; 6797bd88377SAl Viro res = __read_seqcount_begin(&nd->root.dentry->d_seq); 680c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 6817bd88377SAl Viro return res; 68231e6b01fSNick Piggin } 68331e6b01fSNick Piggin 6841d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 685051d3812SIan Kent { 686051d3812SIan Kent dput(path->dentry); 6874ac91378SJan Blunck if (path->mnt != nd->path.mnt) 688051d3812SIan Kent mntput(path->mnt); 689051d3812SIan Kent } 690051d3812SIan Kent 6917b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 6927b9337aaSNick Piggin struct nameidata *nd) 693051d3812SIan Kent { 69431e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 6954ac91378SJan Blunck dput(nd->path.dentry); 69631e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 6974ac91378SJan Blunck mntput(nd->path.mnt); 6989a229683SHuang Shijie } 69931e6b01fSNick Piggin nd->path.mnt = path->mnt; 7004ac91378SJan Blunck nd->path.dentry = path->dentry; 701051d3812SIan Kent } 702051d3812SIan Kent 703b5fb63c1SChristoph Hellwig /* 704b5fb63c1SChristoph Hellwig * Helper to directly jump to a known parsed path from ->follow_link, 705b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 706b5fb63c1SChristoph Hellwig */ 707b5fb63c1SChristoph Hellwig void nd_jump_link(struct nameidata *nd, struct path *path) 708b5fb63c1SChristoph Hellwig { 709b5fb63c1SChristoph Hellwig path_put(&nd->path); 710b5fb63c1SChristoph Hellwig 711b5fb63c1SChristoph Hellwig nd->path = *path; 712b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 713b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 714b5fb63c1SChristoph Hellwig } 715b5fb63c1SChristoph Hellwig 716574197e0SAl Viro static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) 717574197e0SAl Viro { 718574197e0SAl Viro struct inode *inode = link->dentry->d_inode; 719680baacbSAl Viro if (cookie && inode->i_op->put_link) 720680baacbSAl Viro inode->i_op->put_link(link->dentry, cookie); 721574197e0SAl Viro path_put(link); 722574197e0SAl Viro } 723574197e0SAl Viro 724561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 725561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 726800179c9SKees Cook 727800179c9SKees Cook /** 728800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 729800179c9SKees Cook * @link: The path of the symlink 73055852635SRandy Dunlap * @nd: nameidata pathwalk data 731800179c9SKees Cook * 732800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 733800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 734800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 735800179c9SKees Cook * processes from failing races against path names that may change out 736800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 737800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 738800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 739800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 740800179c9SKees Cook * 741800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 742800179c9SKees Cook */ 743800179c9SKees Cook static inline int may_follow_link(struct path *link, struct nameidata *nd) 744800179c9SKees Cook { 745800179c9SKees Cook const struct inode *inode; 746800179c9SKees Cook const struct inode *parent; 747800179c9SKees Cook 748800179c9SKees Cook if (!sysctl_protected_symlinks) 749800179c9SKees Cook return 0; 750800179c9SKees Cook 751800179c9SKees Cook /* Allowed if owner and follower match. */ 752800179c9SKees Cook inode = link->dentry->d_inode; 75381abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 754800179c9SKees Cook return 0; 755800179c9SKees Cook 756800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 757800179c9SKees Cook parent = nd->path.dentry->d_inode; 758800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 759800179c9SKees Cook return 0; 760800179c9SKees Cook 761800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 76281abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 763800179c9SKees Cook return 0; 764800179c9SKees Cook 765ffd8d101SSasha Levin audit_log_link_denied("follow_link", link); 766800179c9SKees Cook path_put_conditional(link, nd); 767800179c9SKees Cook path_put(&nd->path); 768800179c9SKees Cook return -EACCES; 769800179c9SKees Cook } 770800179c9SKees Cook 771800179c9SKees Cook /** 772800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 773800179c9SKees Cook * @inode: the source inode to hardlink from 774800179c9SKees Cook * 775800179c9SKees Cook * Return false if at least one of the following conditions: 776800179c9SKees Cook * - inode is not a regular file 777800179c9SKees Cook * - inode is setuid 778800179c9SKees Cook * - inode is setgid and group-exec 779800179c9SKees Cook * - access failure for read and write 780800179c9SKees Cook * 781800179c9SKees Cook * Otherwise returns true. 782800179c9SKees Cook */ 783800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 784800179c9SKees Cook { 785800179c9SKees Cook umode_t mode = inode->i_mode; 786800179c9SKees Cook 787800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 788800179c9SKees Cook if (!S_ISREG(mode)) 789800179c9SKees Cook return false; 790800179c9SKees Cook 791800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 792800179c9SKees Cook if (mode & S_ISUID) 793800179c9SKees Cook return false; 794800179c9SKees Cook 795800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 796800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 797800179c9SKees Cook return false; 798800179c9SKees Cook 799800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 800800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 801800179c9SKees Cook return false; 802800179c9SKees Cook 803800179c9SKees Cook return true; 804800179c9SKees Cook } 805800179c9SKees Cook 806800179c9SKees Cook /** 807800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 808800179c9SKees Cook * @link: the source to hardlink from 809800179c9SKees Cook * 810800179c9SKees Cook * Block hardlink when all of: 811800179c9SKees Cook * - sysctl_protected_hardlinks enabled 812800179c9SKees Cook * - fsuid does not match inode 813800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 814800179c9SKees Cook * - not CAP_FOWNER 815800179c9SKees Cook * 816800179c9SKees Cook * Returns 0 if successful, -ve on error. 817800179c9SKees Cook */ 818800179c9SKees Cook static int may_linkat(struct path *link) 819800179c9SKees Cook { 820800179c9SKees Cook const struct cred *cred; 821800179c9SKees Cook struct inode *inode; 822800179c9SKees Cook 823800179c9SKees Cook if (!sysctl_protected_hardlinks) 824800179c9SKees Cook return 0; 825800179c9SKees Cook 826800179c9SKees Cook cred = current_cred(); 827800179c9SKees Cook inode = link->dentry->d_inode; 828800179c9SKees Cook 829800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 830800179c9SKees Cook * otherwise, it must be a safe source. 831800179c9SKees Cook */ 83281abe27bSEric W. Biederman if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || 833800179c9SKees Cook capable(CAP_FOWNER)) 834800179c9SKees Cook return 0; 835800179c9SKees Cook 836a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 837800179c9SKees Cook return -EPERM; 838800179c9SKees Cook } 839800179c9SKees Cook 8400a959df5SAl Viro static __always_inline const char * 8410a959df5SAl Viro get_link(struct path *link, struct nameidata *nd, void **p) 8421da177e4SLinus Torvalds { 8437b9337aaSNick Piggin struct dentry *dentry = link->dentry; 8440a959df5SAl Viro struct inode *inode = dentry->d_inode; 8456d7b5aaeSAl Viro int error; 8460a959df5SAl Viro const char *res; 8471da177e4SLinus Torvalds 848844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 849844a3917SAl Viro 8500e794589SAl Viro if (link->mnt == nd->path.mnt) 8510e794589SAl Viro mntget(link->mnt); 8520e794589SAl Viro 8530a959df5SAl Viro res = ERR_PTR(-ELOOP); 8546d7b5aaeSAl Viro if (unlikely(current->total_link_count >= 40)) 8550a959df5SAl Viro goto out; 8566d7b5aaeSAl Viro 857574197e0SAl Viro cond_resched(); 858574197e0SAl Viro current->total_link_count++; 859574197e0SAl Viro 86068ac1234SAl Viro touch_atime(link); 861cd4e91d3SAl Viro 86237882db0SNeilBrown error = security_inode_follow_link(dentry); 8630a959df5SAl Viro res = ERR_PTR(error); 8646d7b5aaeSAl Viro if (error) 8650a959df5SAl Viro goto out; 86636f3b4f6SAl Viro 86786acdca1SAl Viro nd->last_type = LAST_BIND; 868680baacbSAl Viro *p = NULL; 869d4dee48bSAl Viro res = inode->i_link; 870d4dee48bSAl Viro if (!res) { 8710a959df5SAl Viro res = inode->i_op->follow_link(dentry, p, nd); 8720a959df5SAl Viro if (IS_ERR(res)) { 8730a959df5SAl Viro out: 8740a959df5SAl Viro path_put(&nd->path); 8750a959df5SAl Viro path_put(link); 8760a959df5SAl Viro } 877d4dee48bSAl Viro } 8780a959df5SAl Viro return res; 8790a959df5SAl Viro } 8806d7b5aaeSAl Viro 88131e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 88231e6b01fSNick Piggin { 8830714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 8840714a533SAl Viro struct mount *parent; 88531e6b01fSNick Piggin struct dentry *mountpoint; 88631e6b01fSNick Piggin 8870714a533SAl Viro parent = mnt->mnt_parent; 8880714a533SAl Viro if (&parent->mnt == path->mnt) 88931e6b01fSNick Piggin return 0; 890a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 89131e6b01fSNick Piggin path->dentry = mountpoint; 8920714a533SAl Viro path->mnt = &parent->mnt; 89331e6b01fSNick Piggin return 1; 89431e6b01fSNick Piggin } 89531e6b01fSNick Piggin 896f015f126SDavid Howells /* 897f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 898f015f126SDavid Howells * 899f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 900f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 901f015f126SDavid Howells * Up is towards /. 902f015f126SDavid Howells * 903f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 904f015f126SDavid Howells * root. 905f015f126SDavid Howells */ 906bab77ebfSAl Viro int follow_up(struct path *path) 9071da177e4SLinus Torvalds { 9080714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9090714a533SAl Viro struct mount *parent; 9101da177e4SLinus Torvalds struct dentry *mountpoint; 91199b7db7bSNick Piggin 91248a066e7SAl Viro read_seqlock_excl(&mount_lock); 9130714a533SAl Viro parent = mnt->mnt_parent; 9143c0a6163SAl Viro if (parent == mnt) { 91548a066e7SAl Viro read_sequnlock_excl(&mount_lock); 9161da177e4SLinus Torvalds return 0; 9171da177e4SLinus Torvalds } 9180714a533SAl Viro mntget(&parent->mnt); 919a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 92048a066e7SAl Viro read_sequnlock_excl(&mount_lock); 921bab77ebfSAl Viro dput(path->dentry); 922bab77ebfSAl Viro path->dentry = mountpoint; 923bab77ebfSAl Viro mntput(path->mnt); 9240714a533SAl Viro path->mnt = &parent->mnt; 9251da177e4SLinus Torvalds return 1; 9261da177e4SLinus Torvalds } 9274d359507SAl Viro EXPORT_SYMBOL(follow_up); 9281da177e4SLinus Torvalds 929b5c84bf6SNick Piggin /* 9309875cf80SDavid Howells * Perform an automount 9319875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 9329875cf80SDavid Howells * were called with. 9331da177e4SLinus Torvalds */ 9349875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 9359875cf80SDavid Howells bool *need_mntput) 93631e6b01fSNick Piggin { 9379875cf80SDavid Howells struct vfsmount *mnt; 938ea5b778aSDavid Howells int err; 9399875cf80SDavid Howells 9409875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 9419875cf80SDavid Howells return -EREMOTE; 9429875cf80SDavid Howells 9430ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 9440ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 9450ec26fd0SMiklos Szeredi * the name. 9460ec26fd0SMiklos Szeredi * 9470ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 9485a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 9490ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 9500ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 9510ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 9520ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 9535a30d8a2SDavid Howells */ 9545a30d8a2SDavid Howells if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 955d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 9565a30d8a2SDavid Howells path->dentry->d_inode) 9579875cf80SDavid Howells return -EISDIR; 9580ec26fd0SMiklos Szeredi 9599875cf80SDavid Howells current->total_link_count++; 9609875cf80SDavid Howells if (current->total_link_count >= 40) 9619875cf80SDavid Howells return -ELOOP; 9629875cf80SDavid Howells 9639875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 9649875cf80SDavid Howells if (IS_ERR(mnt)) { 9659875cf80SDavid Howells /* 9669875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 9679875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 9689875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 9699875cf80SDavid Howells * 9709875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 9719875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 9729875cf80SDavid Howells * the path is inaccessible and we should say so. 9739875cf80SDavid Howells */ 97449084c3bSAl Viro if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) 9759875cf80SDavid Howells return -EREMOTE; 9769875cf80SDavid Howells return PTR_ERR(mnt); 97731e6b01fSNick Piggin } 978ea5b778aSDavid Howells 9799875cf80SDavid Howells if (!mnt) /* mount collision */ 9809875cf80SDavid Howells return 0; 9819875cf80SDavid Howells 9828aef1884SAl Viro if (!*need_mntput) { 9838aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 9848aef1884SAl Viro mntget(path->mnt); 9858aef1884SAl Viro *need_mntput = true; 9868aef1884SAl Viro } 98719a167afSAl Viro err = finish_automount(mnt, path); 988ea5b778aSDavid Howells 989ea5b778aSDavid Howells switch (err) { 990ea5b778aSDavid Howells case -EBUSY: 991ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 99219a167afSAl Viro return 0; 993ea5b778aSDavid Howells case 0: 9948aef1884SAl Viro path_put(path); 9959875cf80SDavid Howells path->mnt = mnt; 9969875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 9979875cf80SDavid Howells return 0; 99819a167afSAl Viro default: 99919a167afSAl Viro return err; 10009875cf80SDavid Howells } 100119a167afSAl Viro 1002ea5b778aSDavid Howells } 10039875cf80SDavid Howells 10049875cf80SDavid Howells /* 10059875cf80SDavid Howells * Handle a dentry that is managed in some way. 1006cc53ce53SDavid Howells * - Flagged for transit management (autofs) 10079875cf80SDavid Howells * - Flagged as mountpoint 10089875cf80SDavid Howells * - Flagged as automount point 10099875cf80SDavid Howells * 10109875cf80SDavid Howells * This may only be called in refwalk mode. 10119875cf80SDavid Howells * 10129875cf80SDavid Howells * Serialization is taken care of in namespace.c 10139875cf80SDavid Howells */ 10149875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 10159875cf80SDavid Howells { 10168aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 10179875cf80SDavid Howells unsigned managed; 10189875cf80SDavid Howells bool need_mntput = false; 10198aef1884SAl Viro int ret = 0; 10209875cf80SDavid Howells 10219875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 10229875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 10239875cf80SDavid Howells * the components of that value change under us */ 10249875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 10259875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 10269875cf80SDavid Howells unlikely(managed != 0)) { 1027cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1028cc53ce53SDavid Howells * being held. */ 1029cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1030cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1031cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 10321aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1033cc53ce53SDavid Howells if (ret < 0) 10348aef1884SAl Viro break; 1035cc53ce53SDavid Howells } 1036cc53ce53SDavid Howells 10379875cf80SDavid Howells /* Transit to a mounted filesystem. */ 10389875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 10399875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10409875cf80SDavid Howells if (mounted) { 10419875cf80SDavid Howells dput(path->dentry); 10429875cf80SDavid Howells if (need_mntput) 1043463ffb2eSAl Viro mntput(path->mnt); 1044463ffb2eSAl Viro path->mnt = mounted; 1045463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 10469875cf80SDavid Howells need_mntput = true; 10479875cf80SDavid Howells continue; 1048463ffb2eSAl Viro } 1049463ffb2eSAl Viro 10509875cf80SDavid Howells /* Something is mounted on this dentry in another 10519875cf80SDavid Howells * namespace and/or whatever was mounted there in this 105248a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 105348a066e7SAl Viro * get it */ 10541da177e4SLinus Torvalds } 10559875cf80SDavid Howells 10569875cf80SDavid Howells /* Handle an automount point */ 10579875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 10589875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 10599875cf80SDavid Howells if (ret < 0) 10608aef1884SAl Viro break; 10619875cf80SDavid Howells continue; 10629875cf80SDavid Howells } 10639875cf80SDavid Howells 10649875cf80SDavid Howells /* We didn't change the current path point */ 10659875cf80SDavid Howells break; 10669875cf80SDavid Howells } 10678aef1884SAl Viro 10688aef1884SAl Viro if (need_mntput && path->mnt == mnt) 10698aef1884SAl Viro mntput(path->mnt); 10708aef1884SAl Viro if (ret == -EISDIR) 10718aef1884SAl Viro ret = 0; 1072a3fbbde7SAl Viro return ret < 0 ? ret : need_mntput; 10731da177e4SLinus Torvalds } 10741da177e4SLinus Torvalds 1075cc53ce53SDavid Howells int follow_down_one(struct path *path) 10761da177e4SLinus Torvalds { 10771da177e4SLinus Torvalds struct vfsmount *mounted; 10781da177e4SLinus Torvalds 10791c755af4SAl Viro mounted = lookup_mnt(path); 10801da177e4SLinus Torvalds if (mounted) { 10819393bd07SAl Viro dput(path->dentry); 10829393bd07SAl Viro mntput(path->mnt); 10839393bd07SAl Viro path->mnt = mounted; 10849393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 10851da177e4SLinus Torvalds return 1; 10861da177e4SLinus Torvalds } 10871da177e4SLinus Torvalds return 0; 10881da177e4SLinus Torvalds } 10894d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 10901da177e4SLinus Torvalds 1091b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 109262a7375eSIan Kent { 1093b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1094b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 109562a7375eSIan Kent } 109662a7375eSIan Kent 10979875cf80SDavid Howells /* 1098287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1099287548e4SAl Viro * we meet a managed dentry that would need blocking. 11009875cf80SDavid Howells */ 11019875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1102287548e4SAl Viro struct inode **inode) 11039875cf80SDavid Howells { 110462a7375eSIan Kent for (;;) { 1105c7105365SAl Viro struct mount *mounted; 110662a7375eSIan Kent /* 110762a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 110862a7375eSIan Kent * that wants to block transit. 110962a7375eSIan Kent */ 1110b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1111b8faf035SNeilBrown case -ECHILD: 1112b8faf035SNeilBrown default: 1113ab90911fSDavid Howells return false; 1114b8faf035SNeilBrown case -EISDIR: 1115b8faf035SNeilBrown return true; 1116b8faf035SNeilBrown case 0: 1117b8faf035SNeilBrown break; 1118b8faf035SNeilBrown } 111962a7375eSIan Kent 112062a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1121b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 112262a7375eSIan Kent 1123474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 11249875cf80SDavid Howells if (!mounted) 11259875cf80SDavid Howells break; 1126c7105365SAl Viro path->mnt = &mounted->mnt; 1127c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1128a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 11299875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 113059430262SLinus Torvalds /* 113159430262SLinus Torvalds * Update the inode too. We don't need to re-check the 113259430262SLinus Torvalds * dentry sequence number here after this d_inode read, 113359430262SLinus Torvalds * because a mount-point is always pinned. 113459430262SLinus Torvalds */ 113559430262SLinus Torvalds *inode = path->dentry->d_inode; 11369875cf80SDavid Howells } 1137f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1138b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1139287548e4SAl Viro } 1140287548e4SAl Viro 114131e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 114231e6b01fSNick Piggin { 11434023bfc9SAl Viro struct inode *inode = nd->inode; 11447bd88377SAl Viro if (!nd->root.mnt) 114531e6b01fSNick Piggin set_root_rcu(nd); 114631e6b01fSNick Piggin 114731e6b01fSNick Piggin while (1) { 114831e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 114931e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 115031e6b01fSNick Piggin break; 115131e6b01fSNick Piggin } 115231e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 115331e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 115431e6b01fSNick Piggin struct dentry *parent = old->d_parent; 115531e6b01fSNick Piggin unsigned seq; 115631e6b01fSNick Piggin 11574023bfc9SAl Viro inode = parent->d_inode; 115831e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 115931e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1160ef7562d5SAl Viro goto failed; 116131e6b01fSNick Piggin nd->path.dentry = parent; 116231e6b01fSNick Piggin nd->seq = seq; 116331e6b01fSNick Piggin break; 116431e6b01fSNick Piggin } 116531e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 116631e6b01fSNick Piggin break; 11674023bfc9SAl Viro inode = nd->path.dentry->d_inode; 116831e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 116931e6b01fSNick Piggin } 1170b37199e6SAl Viro while (d_mountpoint(nd->path.dentry)) { 1171b37199e6SAl Viro struct mount *mounted; 1172b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1173b37199e6SAl Viro if (!mounted) 1174b37199e6SAl Viro break; 1175b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1176b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 11774023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1178b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1179f5be3e29SAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1180b37199e6SAl Viro goto failed; 1181b37199e6SAl Viro } 11824023bfc9SAl Viro nd->inode = inode; 118331e6b01fSNick Piggin return 0; 1184ef7562d5SAl Viro 1185ef7562d5SAl Viro failed: 1186ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 11875b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1188ef7562d5SAl Viro nd->root.mnt = NULL; 11898b61e74fSAl Viro rcu_read_unlock(); 1190ef7562d5SAl Viro return -ECHILD; 119131e6b01fSNick Piggin } 119231e6b01fSNick Piggin 11939875cf80SDavid Howells /* 1194cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1195cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1196cc53ce53SDavid Howells * caller is permitted to proceed or not. 1197cc53ce53SDavid Howells */ 11987cc90cc3SAl Viro int follow_down(struct path *path) 1199cc53ce53SDavid Howells { 1200cc53ce53SDavid Howells unsigned managed; 1201cc53ce53SDavid Howells int ret; 1202cc53ce53SDavid Howells 1203cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1204cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1205cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1206cc53ce53SDavid Howells * being held. 1207cc53ce53SDavid Howells * 1208cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1209cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1210cc53ce53SDavid Howells * other than its daemon the right to mount on its 1211cc53ce53SDavid Howells * superstructure. 1212cc53ce53SDavid Howells * 1213cc53ce53SDavid Howells * The filesystem may sleep at this point. 1214cc53ce53SDavid Howells */ 1215cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1216cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1217cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1218ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 12191aed3e42SAl Viro path->dentry, false); 1220cc53ce53SDavid Howells if (ret < 0) 1221cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1222cc53ce53SDavid Howells } 1223cc53ce53SDavid Howells 1224cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1225cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1226cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1227cc53ce53SDavid Howells if (!mounted) 1228cc53ce53SDavid Howells break; 1229cc53ce53SDavid Howells dput(path->dentry); 1230cc53ce53SDavid Howells mntput(path->mnt); 1231cc53ce53SDavid Howells path->mnt = mounted; 1232cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1233cc53ce53SDavid Howells continue; 1234cc53ce53SDavid Howells } 1235cc53ce53SDavid Howells 1236cc53ce53SDavid Howells /* Don't handle automount points here */ 1237cc53ce53SDavid Howells break; 1238cc53ce53SDavid Howells } 1239cc53ce53SDavid Howells return 0; 1240cc53ce53SDavid Howells } 12414d359507SAl Viro EXPORT_SYMBOL(follow_down); 1242cc53ce53SDavid Howells 1243cc53ce53SDavid Howells /* 12449875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 12459875cf80SDavid Howells */ 12469875cf80SDavid Howells static void follow_mount(struct path *path) 12479875cf80SDavid Howells { 12489875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 12499875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12509875cf80SDavid Howells if (!mounted) 12519875cf80SDavid Howells break; 12529875cf80SDavid Howells dput(path->dentry); 12539875cf80SDavid Howells mntput(path->mnt); 12549875cf80SDavid Howells path->mnt = mounted; 12559875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 12569875cf80SDavid Howells } 12579875cf80SDavid Howells } 12589875cf80SDavid Howells 125931e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 12601da177e4SLinus Torvalds { 12617bd88377SAl Viro if (!nd->root.mnt) 12622a737871SAl Viro set_root(nd); 1263e518ddb7SAndreas Mohr 12641da177e4SLinus Torvalds while(1) { 12654ac91378SJan Blunck struct dentry *old = nd->path.dentry; 12661da177e4SLinus Torvalds 12672a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 12682a737871SAl Viro nd->path.mnt == nd->root.mnt) { 12691da177e4SLinus Torvalds break; 12701da177e4SLinus Torvalds } 12714ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 12723088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 12733088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 12741da177e4SLinus Torvalds dput(old); 12751da177e4SLinus Torvalds break; 12761da177e4SLinus Torvalds } 12773088dd70SAl Viro if (!follow_up(&nd->path)) 12781da177e4SLinus Torvalds break; 12791da177e4SLinus Torvalds } 128079ed0226SAl Viro follow_mount(&nd->path); 128131e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 12821da177e4SLinus Torvalds } 12831da177e4SLinus Torvalds 12841da177e4SLinus Torvalds /* 1285bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1286bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1287bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1288bad61189SMiklos Szeredi * 1289bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1290baa03890SNick Piggin */ 1291bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1292201f956eSAl Viro unsigned int flags, bool *need_lookup) 1293baa03890SNick Piggin { 1294baa03890SNick Piggin struct dentry *dentry; 1295bad61189SMiklos Szeredi int error; 1296baa03890SNick Piggin 1297bad61189SMiklos Szeredi *need_lookup = false; 1298bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1299bad61189SMiklos Szeredi if (dentry) { 130039e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1301201f956eSAl Viro error = d_revalidate(dentry, flags); 1302bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1303bad61189SMiklos Szeredi if (error < 0) { 1304bad61189SMiklos Szeredi dput(dentry); 1305bad61189SMiklos Szeredi return ERR_PTR(error); 13065542aa2fSEric W. Biederman } else { 13075542aa2fSEric W. Biederman d_invalidate(dentry); 1308bad61189SMiklos Szeredi dput(dentry); 1309bad61189SMiklos Szeredi dentry = NULL; 1310bad61189SMiklos Szeredi } 1311bad61189SMiklos Szeredi } 1312bad61189SMiklos Szeredi } 1313bad61189SMiklos Szeredi } 1314baa03890SNick Piggin 1315bad61189SMiklos Szeredi if (!dentry) { 1316bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1317baa03890SNick Piggin if (unlikely(!dentry)) 1318baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1319baa03890SNick Piggin 1320bad61189SMiklos Szeredi *need_lookup = true; 1321baa03890SNick Piggin } 1322baa03890SNick Piggin return dentry; 1323baa03890SNick Piggin } 1324baa03890SNick Piggin 1325baa03890SNick Piggin /* 132613a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 132713a2c3beSJ. Bruce Fields * unhashed. 1328bad61189SMiklos Szeredi * 1329bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 133044396f4bSJosef Bacik */ 1331bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 133272bd866aSAl Viro unsigned int flags) 133344396f4bSJosef Bacik { 133444396f4bSJosef Bacik struct dentry *old; 133544396f4bSJosef Bacik 133644396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1337bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1338e188dc02SMiklos Szeredi dput(dentry); 133944396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1340e188dc02SMiklos Szeredi } 134144396f4bSJosef Bacik 134272bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 134344396f4bSJosef Bacik if (unlikely(old)) { 134444396f4bSJosef Bacik dput(dentry); 134544396f4bSJosef Bacik dentry = old; 134644396f4bSJosef Bacik } 134744396f4bSJosef Bacik return dentry; 134844396f4bSJosef Bacik } 134944396f4bSJosef Bacik 1350a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 135172bd866aSAl Viro struct dentry *base, unsigned int flags) 1352a3255546SAl Viro { 1353bad61189SMiklos Szeredi bool need_lookup; 1354a3255546SAl Viro struct dentry *dentry; 1355a3255546SAl Viro 135672bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1357bad61189SMiklos Szeredi if (!need_lookup) 1358a3255546SAl Viro return dentry; 1359bad61189SMiklos Szeredi 136072bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1361a3255546SAl Viro } 1362a3255546SAl Viro 136344396f4bSJosef Bacik /* 13641da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 13651da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 13661da177e4SLinus Torvalds * It _is_ time-critical. 13671da177e4SLinus Torvalds */ 1368e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 136931e6b01fSNick Piggin struct path *path, struct inode **inode) 13701da177e4SLinus Torvalds { 13714ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 137231e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 13735a18fff2SAl Viro int need_reval = 1; 13745a18fff2SAl Viro int status = 1; 13759875cf80SDavid Howells int err; 13769875cf80SDavid Howells 13773cac260aSAl Viro /* 1378b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1379b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1380b04f784eSNick Piggin * do the non-racy lookup, below. 1381b04f784eSNick Piggin */ 138231e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 138331e6b01fSNick Piggin unsigned seq; 1384766c4cbfSAl Viro bool negative; 1385da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 13865a18fff2SAl Viro if (!dentry) 13875a18fff2SAl Viro goto unlazy; 13885a18fff2SAl Viro 138912f8ad4bSLinus Torvalds /* 139012f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 139112f8ad4bSLinus Torvalds * the dentry name information from lookup. 139212f8ad4bSLinus Torvalds */ 139312f8ad4bSLinus Torvalds *inode = dentry->d_inode; 1394766c4cbfSAl Viro negative = d_is_negative(dentry); 139512f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 139612f8ad4bSLinus Torvalds return -ECHILD; 1397766c4cbfSAl Viro if (negative) 1398766c4cbfSAl Viro return -ENOENT; 139912f8ad4bSLinus Torvalds 140012f8ad4bSLinus Torvalds /* 140112f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 140212f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 140312f8ad4bSLinus Torvalds * 140412f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 140512f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 140612f8ad4bSLinus Torvalds */ 140731e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 140831e6b01fSNick Piggin return -ECHILD; 140931e6b01fSNick Piggin nd->seq = seq; 14105a18fff2SAl Viro 141124643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 14124ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14135a18fff2SAl Viro if (unlikely(status <= 0)) { 14145a18fff2SAl Viro if (status != -ECHILD) 14155a18fff2SAl Viro need_reval = 0; 14165a18fff2SAl Viro goto unlazy; 14175a18fff2SAl Viro } 141824643087SAl Viro } 141931e6b01fSNick Piggin path->mnt = mnt; 142031e6b01fSNick Piggin path->dentry = dentry; 1421b8faf035SNeilBrown if (likely(__follow_mount_rcu(nd, path, inode))) 14229875cf80SDavid Howells return 0; 14235a18fff2SAl Viro unlazy: 142419660af7SAl Viro if (unlazy_walk(nd, dentry)) 14255a18fff2SAl Viro return -ECHILD; 14265a18fff2SAl Viro } else { 1427e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 142824643087SAl Viro } 14295a18fff2SAl Viro 143081e6f520SAl Viro if (unlikely(!dentry)) 143181e6f520SAl Viro goto need_lookup; 14325a18fff2SAl Viro 14335a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 14344ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14355a18fff2SAl Viro if (unlikely(status <= 0)) { 14365a18fff2SAl Viro if (status < 0) { 14375a18fff2SAl Viro dput(dentry); 14385a18fff2SAl Viro return status; 14395a18fff2SAl Viro } 14405542aa2fSEric W. Biederman d_invalidate(dentry); 14415a18fff2SAl Viro dput(dentry); 144281e6f520SAl Viro goto need_lookup; 14435a18fff2SAl Viro } 1444697f514dSMiklos Szeredi 1445766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1446766c4cbfSAl Viro dput(dentry); 1447766c4cbfSAl Viro return -ENOENT; 1448766c4cbfSAl Viro } 14491da177e4SLinus Torvalds path->mnt = mnt; 14501da177e4SLinus Torvalds path->dentry = dentry; 14519875cf80SDavid Howells err = follow_managed(path, nd->flags); 145289312214SIan Kent if (unlikely(err < 0)) { 145389312214SIan Kent path_put_conditional(path, nd); 14549875cf80SDavid Howells return err; 145589312214SIan Kent } 1456a3fbbde7SAl Viro if (err) 1457a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 145831e6b01fSNick Piggin *inode = path->dentry->d_inode; 14591da177e4SLinus Torvalds return 0; 146081e6f520SAl Viro 146181e6f520SAl Viro need_lookup: 1462697f514dSMiklos Szeredi return 1; 1463697f514dSMiklos Szeredi } 1464697f514dSMiklos Szeredi 1465697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1466cc2a5271SAl Viro static int lookup_slow(struct nameidata *nd, struct path *path) 1467697f514dSMiklos Szeredi { 1468697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1469697f514dSMiklos Szeredi int err; 1470697f514dSMiklos Szeredi 1471697f514dSMiklos Szeredi parent = nd->path.dentry; 147281e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 147381e6f520SAl Viro 147481e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 1475cc2a5271SAl Viro dentry = __lookup_hash(&nd->last, parent, nd->flags); 147681e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 147781e6f520SAl Viro if (IS_ERR(dentry)) 147881e6f520SAl Viro return PTR_ERR(dentry); 1479697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1480697f514dSMiklos Szeredi path->dentry = dentry; 1481697f514dSMiklos Szeredi err = follow_managed(path, nd->flags); 1482697f514dSMiklos Szeredi if (unlikely(err < 0)) { 1483697f514dSMiklos Szeredi path_put_conditional(path, nd); 1484697f514dSMiklos Szeredi return err; 1485697f514dSMiklos Szeredi } 1486697f514dSMiklos Szeredi if (err) 1487697f514dSMiklos Szeredi nd->flags |= LOOKUP_JUMPED; 1488697f514dSMiklos Szeredi return 0; 14891da177e4SLinus Torvalds } 14901da177e4SLinus Torvalds 149152094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 149252094c8aSAl Viro { 149352094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 14944ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 149552094c8aSAl Viro if (err != -ECHILD) 149652094c8aSAl Viro return err; 149719660af7SAl Viro if (unlazy_walk(nd, NULL)) 149852094c8aSAl Viro return -ECHILD; 149952094c8aSAl Viro } 15004ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 150152094c8aSAl Viro } 150252094c8aSAl Viro 15039856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 15049856fa1bSAl Viro { 15059856fa1bSAl Viro if (type == LAST_DOTDOT) { 15069856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 15079856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 15089856fa1bSAl Viro return -ECHILD; 15099856fa1bSAl Viro } else 15109856fa1bSAl Viro follow_dotdot(nd); 15119856fa1bSAl Viro } 15129856fa1bSAl Viro return 0; 15139856fa1bSAl Viro } 15149856fa1bSAl Viro 1515951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1516951361f9SAl Viro { 1517951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1518951361f9SAl Viro path_put(&nd->path); 1519951361f9SAl Viro } else { 1520951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 15215b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1522951361f9SAl Viro nd->root.mnt = NULL; 15238b61e74fSAl Viro rcu_read_unlock(); 1524951361f9SAl Viro } 1525951361f9SAl Viro } 1526951361f9SAl Viro 15273ddcd056SLinus Torvalds /* 15283ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 15293ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 15303ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 15313ddcd056SLinus Torvalds * for the common case. 15323ddcd056SLinus Torvalds */ 1533b18825a7SDavid Howells static inline int should_follow_link(struct dentry *dentry, int follow) 15343ddcd056SLinus Torvalds { 1535b18825a7SDavid Howells return unlikely(d_is_symlink(dentry)) ? follow : 0; 15363ddcd056SLinus Torvalds } 15373ddcd056SLinus Torvalds 1538caa85634SAl Viro static int walk_component(struct nameidata *nd, int follow) 1539ce57dfc1SAl Viro { 1540caa85634SAl Viro struct path path; 1541ce57dfc1SAl Viro struct inode *inode; 1542ce57dfc1SAl Viro int err; 1543ce57dfc1SAl Viro /* 1544ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1545ce57dfc1SAl Viro * to be able to know about the current root directory and 1546ce57dfc1SAl Viro * parent relationships. 1547ce57dfc1SAl Viro */ 154821b9b073SAl Viro if (unlikely(nd->last_type != LAST_NORM)) 154921b9b073SAl Viro return handle_dots(nd, nd->last_type); 1550caa85634SAl Viro err = lookup_fast(nd, &path, &inode); 1551ce57dfc1SAl Viro if (unlikely(err)) { 1552697f514dSMiklos Szeredi if (err < 0) 1553697f514dSMiklos Szeredi goto out_err; 1554697f514dSMiklos Szeredi 1555caa85634SAl Viro err = lookup_slow(nd, &path); 1556697f514dSMiklos Szeredi if (err < 0) 1557697f514dSMiklos Szeredi goto out_err; 1558697f514dSMiklos Szeredi 1559caa85634SAl Viro inode = path.dentry->d_inode; 1560697f514dSMiklos Szeredi err = -ENOENT; 1561caa85634SAl Viro if (d_is_negative(path.dentry)) 1562697f514dSMiklos Szeredi goto out_path_put; 1563766c4cbfSAl Viro } 1564697f514dSMiklos Szeredi 1565caa85634SAl Viro if (should_follow_link(path.dentry, follow)) { 156619660af7SAl Viro if (nd->flags & LOOKUP_RCU) { 1567caa85634SAl Viro if (unlikely(nd->path.mnt != path.mnt || 1568caa85634SAl Viro unlazy_walk(nd, path.dentry))) { 1569697f514dSMiklos Szeredi err = -ECHILD; 1570697f514dSMiklos Szeredi goto out_err; 157119660af7SAl Viro } 157219660af7SAl Viro } 1573caa85634SAl Viro BUG_ON(inode != path.dentry->d_inode); 1574caa85634SAl Viro nd->link = path; 1575ce57dfc1SAl Viro return 1; 1576ce57dfc1SAl Viro } 1577caa85634SAl Viro path_to_nameidata(&path, nd); 1578ce57dfc1SAl Viro nd->inode = inode; 1579ce57dfc1SAl Viro return 0; 1580697f514dSMiklos Szeredi 1581697f514dSMiklos Szeredi out_path_put: 1582caa85634SAl Viro path_to_nameidata(&path, nd); 1583697f514dSMiklos Szeredi out_err: 1584697f514dSMiklos Szeredi terminate_walk(nd); 1585697f514dSMiklos Szeredi return err; 1586ce57dfc1SAl Viro } 1587ce57dfc1SAl Viro 15881da177e4SLinus Torvalds /* 1589bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1590bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1591bfcfaa77SLinus Torvalds * 1592bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1593bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1594bfcfaa77SLinus Torvalds * fast. 1595bfcfaa77SLinus Torvalds * 1596bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1597bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1598bfcfaa77SLinus Torvalds * crossing operation. 1599bfcfaa77SLinus Torvalds * 1600bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1601bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1602bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1603bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1604bfcfaa77SLinus Torvalds */ 1605bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1606bfcfaa77SLinus Torvalds 1607f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1608bfcfaa77SLinus Torvalds 1609f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1610bfcfaa77SLinus Torvalds 1611bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1612bfcfaa77SLinus Torvalds { 161399d263d4SLinus Torvalds return hash_64(hash, 32); 1614bfcfaa77SLinus Torvalds } 1615bfcfaa77SLinus Torvalds 1616bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1617bfcfaa77SLinus Torvalds 1618bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1619bfcfaa77SLinus Torvalds 1620bfcfaa77SLinus Torvalds #endif 1621bfcfaa77SLinus Torvalds 1622bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1623bfcfaa77SLinus Torvalds { 1624bfcfaa77SLinus Torvalds unsigned long a, mask; 1625bfcfaa77SLinus Torvalds unsigned long hash = 0; 1626bfcfaa77SLinus Torvalds 1627bfcfaa77SLinus Torvalds for (;;) { 1628e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1629bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1630bfcfaa77SLinus Torvalds break; 1631bfcfaa77SLinus Torvalds hash += a; 1632f132c5beSAl Viro hash *= 9; 1633bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1634bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1635bfcfaa77SLinus Torvalds if (!len) 1636bfcfaa77SLinus Torvalds goto done; 1637bfcfaa77SLinus Torvalds } 1638a5c21dceSWill Deacon mask = bytemask_from_count(len); 1639bfcfaa77SLinus Torvalds hash += mask & a; 1640bfcfaa77SLinus Torvalds done: 1641bfcfaa77SLinus Torvalds return fold_hash(hash); 1642bfcfaa77SLinus Torvalds } 1643bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1644bfcfaa77SLinus Torvalds 1645bfcfaa77SLinus Torvalds /* 1646bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1647d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1648bfcfaa77SLinus Torvalds */ 1649d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1650bfcfaa77SLinus Torvalds { 165136126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 165236126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1653bfcfaa77SLinus Torvalds 1654bfcfaa77SLinus Torvalds hash = a = 0; 1655bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1656bfcfaa77SLinus Torvalds do { 1657bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1658bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1659e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 166036126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 166136126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1662bfcfaa77SLinus Torvalds 166336126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 166436126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 166536126f8fSLinus Torvalds 166636126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 166736126f8fSLinus Torvalds 166836126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 16699226b5b4SLinus Torvalds len += find_zero(mask); 1670d6bb3e90SLinus Torvalds return hashlen_create(fold_hash(hash), len); 1671bfcfaa77SLinus Torvalds } 1672bfcfaa77SLinus Torvalds 1673bfcfaa77SLinus Torvalds #else 1674bfcfaa77SLinus Torvalds 16750145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 16760145acc2SLinus Torvalds { 16770145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 16780145acc2SLinus Torvalds while (len--) 16790145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 16800145acc2SLinus Torvalds return end_name_hash(hash); 16810145acc2SLinus Torvalds } 1682ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 16830145acc2SLinus Torvalds 16843ddcd056SLinus Torvalds /* 1685200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1686200e9ef7SLinus Torvalds * one character. 1687200e9ef7SLinus Torvalds */ 1688d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1689200e9ef7SLinus Torvalds { 1690200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1691200e9ef7SLinus Torvalds unsigned long len = 0, c; 1692200e9ef7SLinus Torvalds 1693200e9ef7SLinus Torvalds c = (unsigned char)*name; 1694200e9ef7SLinus Torvalds do { 1695200e9ef7SLinus Torvalds len++; 1696200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1697200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1698200e9ef7SLinus Torvalds } while (c && c != '/'); 1699d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 1700200e9ef7SLinus Torvalds } 1701200e9ef7SLinus Torvalds 1702bfcfaa77SLinus Torvalds #endif 1703bfcfaa77SLinus Torvalds 1704200e9ef7SLinus Torvalds /* 17051da177e4SLinus Torvalds * Name resolution. 1706ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1707ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 17081da177e4SLinus Torvalds * 1709ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1710ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 17111da177e4SLinus Torvalds */ 17126de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 17131da177e4SLinus Torvalds { 17141da177e4SLinus Torvalds int err; 17151da177e4SLinus Torvalds 17161da177e4SLinus Torvalds while (*name=='/') 17171da177e4SLinus Torvalds name++; 17181da177e4SLinus Torvalds if (!*name) 1719086e183aSAl Viro return 0; 17201da177e4SLinus Torvalds 17211da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 17221da177e4SLinus Torvalds for(;;) { 1723d6bb3e90SLinus Torvalds u64 hash_len; 1724fe479a58SAl Viro int type; 17251da177e4SLinus Torvalds 172652094c8aSAl Viro err = may_lookup(nd); 17271da177e4SLinus Torvalds if (err) 17281da177e4SLinus Torvalds break; 17291da177e4SLinus Torvalds 1730d6bb3e90SLinus Torvalds hash_len = hash_name(name); 17311da177e4SLinus Torvalds 1732fe479a58SAl Viro type = LAST_NORM; 1733d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 1734fe479a58SAl Viro case 2: 1735200e9ef7SLinus Torvalds if (name[1] == '.') { 1736fe479a58SAl Viro type = LAST_DOTDOT; 173716c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 173816c2cd71SAl Viro } 1739fe479a58SAl Viro break; 1740fe479a58SAl Viro case 1: 1741fe479a58SAl Viro type = LAST_DOT; 1742fe479a58SAl Viro } 17435a202bcdSAl Viro if (likely(type == LAST_NORM)) { 17445a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 174516c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 17465a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 1747a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 1748da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 17495a202bcdSAl Viro if (err < 0) 17505a202bcdSAl Viro break; 1751d6bb3e90SLinus Torvalds hash_len = this.hash_len; 1752d6bb3e90SLinus Torvalds name = this.name; 17535a202bcdSAl Viro } 17545a202bcdSAl Viro } 1755fe479a58SAl Viro 1756d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 1757d6bb3e90SLinus Torvalds nd->last.name = name; 17585f4a6a69SAl Viro nd->last_type = type; 17595f4a6a69SAl Viro 1760d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 1761d6bb3e90SLinus Torvalds if (!*name) 17625f4a6a69SAl Viro return 0; 1763200e9ef7SLinus Torvalds /* 1764200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1765200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1766200e9ef7SLinus Torvalds */ 1767200e9ef7SLinus Torvalds do { 1768d6bb3e90SLinus Torvalds name++; 1769d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 1770d6bb3e90SLinus Torvalds if (!*name) 17715f4a6a69SAl Viro return 0; 17725f4a6a69SAl Viro 1773caa85634SAl Viro err = walk_component(nd, LOOKUP_FOLLOW); 1774ce57dfc1SAl Viro if (err < 0) 1775ce57dfc1SAl Viro return err; 1776fe479a58SAl Viro 1777ce57dfc1SAl Viro if (err) { 17785a460275SAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 17795a460275SAl Viro path_put_conditional(&nd->link, nd); 17805a460275SAl Viro path_put(&nd->path); 17815a460275SAl Viro return -ELOOP; 17825a460275SAl Viro } 17835a460275SAl Viro BUG_ON(nd->depth >= MAX_NESTED_LINKS); 17845a460275SAl Viro 17855a460275SAl Viro nd->depth++; 17865a460275SAl Viro current->link_count++; 17875a460275SAl Viro 17885a460275SAl Viro do { 17895a460275SAl Viro struct path link = nd->link; 17905a460275SAl Viro void *cookie; 1791172a39a0SAl Viro const char *s = get_link(&link, nd, &cookie); 17925a460275SAl Viro 1793172a39a0SAl Viro if (unlikely(IS_ERR(s))) { 1794172a39a0SAl Viro err = PTR_ERR(s); 17955a460275SAl Viro break; 1796172a39a0SAl Viro } 1797172a39a0SAl Viro err = 0; 1798172a39a0SAl Viro if (likely(s)) { 1799172a39a0SAl Viro if (*s == '/') { 1800172a39a0SAl Viro if (!nd->root.mnt) 1801172a39a0SAl Viro set_root(nd); 1802172a39a0SAl Viro path_put(&nd->path); 1803172a39a0SAl Viro nd->path = nd->root; 1804172a39a0SAl Viro path_get(&nd->root); 1805172a39a0SAl Viro nd->flags |= LOOKUP_JUMPED; 1806172a39a0SAl Viro } 1807172a39a0SAl Viro nd->inode = nd->path.dentry->d_inode; 1808172a39a0SAl Viro err = link_path_walk(s, nd); 1809172a39a0SAl Viro if (unlikely(err)) { 1810172a39a0SAl Viro put_link(nd, &link, cookie); 1811172a39a0SAl Viro break; 1812172a39a0SAl Viro } 1813172a39a0SAl Viro } 18145a460275SAl Viro err = walk_component(nd, LOOKUP_FOLLOW); 18155a460275SAl Viro put_link(nd, &link, cookie); 18165a460275SAl Viro } while (err > 0); 18175a460275SAl Viro 18185a460275SAl Viro current->link_count--; 18195a460275SAl Viro nd->depth--; 18201da177e4SLinus Torvalds if (err) 1821a7472babSAl Viro return err; 182231e6b01fSNick Piggin } 182344b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 18243ddcd056SLinus Torvalds err = -ENOTDIR; 18253ddcd056SLinus Torvalds break; 18265f4a6a69SAl Viro } 1827ce57dfc1SAl Viro } 1828951361f9SAl Viro terminate_walk(nd); 18291da177e4SLinus Torvalds return err; 18301da177e4SLinus Torvalds } 18311da177e4SLinus Torvalds 18326e8a1f87SAl Viro static int path_init(int dfd, const struct filename *name, unsigned int flags, 18335e53084dSAl Viro struct nameidata *nd) 183431e6b01fSNick Piggin { 183531e6b01fSNick Piggin int retval = 0; 1836fd2f7cb5SAl Viro const char *s = name->name; 183731e6b01fSNick Piggin 183831e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 1839980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 184031e6b01fSNick Piggin nd->depth = 0; 18415e53084dSAl Viro nd->base = NULL; 18425b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 1843b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 1844b18825a7SDavid Howells struct inode *inode = root->d_inode; 1845fd2f7cb5SAl Viro if (*s) { 184644b1d530SMiklos Szeredi if (!d_can_lookup(root)) 18475b6ca027SAl Viro return -ENOTDIR; 18485b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 18495b6ca027SAl Viro if (retval) 18505b6ca027SAl Viro return retval; 185173d049a4SAl Viro } 18525b6ca027SAl Viro nd->path = nd->root; 18535b6ca027SAl Viro nd->inode = inode; 18545b6ca027SAl Viro if (flags & LOOKUP_RCU) { 18558b61e74fSAl Viro rcu_read_lock(); 18565b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 185748a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 18585b6ca027SAl Viro } else { 18595b6ca027SAl Viro path_get(&nd->path); 18605b6ca027SAl Viro } 1861d465887fSAl Viro goto done; 18625b6ca027SAl Viro } 18635b6ca027SAl Viro 186431e6b01fSNick Piggin nd->root.mnt = NULL; 186531e6b01fSNick Piggin 186648a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 1867fd2f7cb5SAl Viro if (*s == '/') { 1868e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 18698b61e74fSAl Viro rcu_read_lock(); 18707bd88377SAl Viro nd->seq = set_root_rcu(nd); 1871e41f7d4eSAl Viro } else { 1872e41f7d4eSAl Viro set_root(nd); 1873e41f7d4eSAl Viro path_get(&nd->root); 1874e41f7d4eSAl Viro } 187531e6b01fSNick Piggin nd->path = nd->root; 187631e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1877e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 187831e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1879c28cc364SNick Piggin unsigned seq; 188031e6b01fSNick Piggin 18818b61e74fSAl Viro rcu_read_lock(); 188231e6b01fSNick Piggin 1883c28cc364SNick Piggin do { 1884c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 188531e6b01fSNick Piggin nd->path = fs->pwd; 1886c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1887c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1888e41f7d4eSAl Viro } else { 1889e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1890e41f7d4eSAl Viro } 189131e6b01fSNick Piggin } else { 1892582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 18932903ff01SAl Viro struct fd f = fdget_raw(dfd); 189431e6b01fSNick Piggin struct dentry *dentry; 189531e6b01fSNick Piggin 18962903ff01SAl Viro if (!f.file) 18972903ff01SAl Viro return -EBADF; 189831e6b01fSNick Piggin 18992903ff01SAl Viro dentry = f.file->f_path.dentry; 190031e6b01fSNick Piggin 1901fd2f7cb5SAl Viro if (*s) { 190244b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 19032903ff01SAl Viro fdput(f); 19042903ff01SAl Viro return -ENOTDIR; 1905f52e0c11SAl Viro } 19062903ff01SAl Viro } 19072903ff01SAl Viro 19082903ff01SAl Viro nd->path = f.file->f_path; 1909e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 19109c225f26SLinus Torvalds if (f.flags & FDPUT_FPUT) 19115e53084dSAl Viro nd->base = f.file; 1912c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 19138b61e74fSAl Viro rcu_read_lock(); 19145590ff0dSUlrich Drepper } else { 19152903ff01SAl Viro path_get(&nd->path); 19162903ff01SAl Viro fdput(f); 19171da177e4SLinus Torvalds } 1918e41f7d4eSAl Viro } 1919e41f7d4eSAl Viro 192031e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 19214023bfc9SAl Viro if (!(flags & LOOKUP_RCU)) 1922d465887fSAl Viro goto done; 19234023bfc9SAl Viro if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) 1924d465887fSAl Viro goto done; 19254023bfc9SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 19264023bfc9SAl Viro nd->root.mnt = NULL; 19274023bfc9SAl Viro rcu_read_unlock(); 19284023bfc9SAl Viro return -ECHILD; 1929d465887fSAl Viro done: 1930d465887fSAl Viro current->total_link_count = 0; 1931fd2f7cb5SAl Viro return link_path_walk(s, nd); 19329b4a9b14SAl Viro } 19339b4a9b14SAl Viro 1934893b7775SAl Viro static void path_cleanup(struct nameidata *nd) 1935893b7775SAl Viro { 1936893b7775SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 1937893b7775SAl Viro path_put(&nd->root); 1938893b7775SAl Viro nd->root.mnt = NULL; 1939893b7775SAl Viro } 1940893b7775SAl Viro if (unlikely(nd->base)) 1941893b7775SAl Viro fput(nd->base); 19429b4a9b14SAl Viro } 19439b4a9b14SAl Viro 194495fa25d9SAl Viro static int trailing_symlink(struct path *link, struct nameidata *nd, void **p) 194595fa25d9SAl Viro { 194695fa25d9SAl Viro const char *s; 194795fa25d9SAl Viro int error = may_follow_link(link, nd); 194895fa25d9SAl Viro if (unlikely(error)) 194995fa25d9SAl Viro return error; 195095fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 195195fa25d9SAl Viro s = get_link(link, nd, p); 195295fa25d9SAl Viro if (unlikely(IS_ERR(s))) 195395fa25d9SAl Viro return PTR_ERR(s); 195495fa25d9SAl Viro if (unlikely(!s)) 195595fa25d9SAl Viro return 0; 195695fa25d9SAl Viro if (*s == '/') { 195795fa25d9SAl Viro if (!nd->root.mnt) 195895fa25d9SAl Viro set_root(nd); 195995fa25d9SAl Viro path_put(&nd->path); 196095fa25d9SAl Viro nd->path = nd->root; 196195fa25d9SAl Viro path_get(&nd->root); 196295fa25d9SAl Viro nd->flags |= LOOKUP_JUMPED; 196395fa25d9SAl Viro } 196495fa25d9SAl Viro nd->inode = nd->path.dentry->d_inode; 196595fa25d9SAl Viro error = link_path_walk(s, nd); 196695fa25d9SAl Viro if (unlikely(error)) 196795fa25d9SAl Viro put_link(nd, link, *p); 196895fa25d9SAl Viro return error; 196995fa25d9SAl Viro } 197095fa25d9SAl Viro 1971caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 1972bd92d7feSAl Viro { 1973bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1974bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1975bd92d7feSAl Viro 1976bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 1977caa85634SAl Viro return walk_component(nd, nd->flags & LOOKUP_FOLLOW); 1978bd92d7feSAl Viro } 1979bd92d7feSAl Viro 19809b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 19815eb6b495SAl Viro static int path_lookupat(int dfd, const struct filename *name, 19829b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 19839b4a9b14SAl Viro { 1984bd92d7feSAl Viro int err; 198531e6b01fSNick Piggin 198631e6b01fSNick Piggin /* 198731e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 198831e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 198931e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 199031e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 199131e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 199231e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 199331e6b01fSNick Piggin * analogue, foo_rcu(). 199431e6b01fSNick Piggin * 199531e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 199631e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 199731e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 199831e6b01fSNick Piggin * be able to complete). 199931e6b01fSNick Piggin */ 20006e8a1f87SAl Viro err = path_init(dfd, name, flags, nd); 2001bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 2002caa85634SAl Viro err = lookup_last(nd); 2003bd92d7feSAl Viro while (err > 0) { 2004bd92d7feSAl Viro void *cookie; 2005caa85634SAl Viro struct path link = nd->link; 200695fa25d9SAl Viro err = trailing_symlink(&link, nd, &cookie); 20076d7b5aaeSAl Viro if (err) 20086d7b5aaeSAl Viro break; 2009caa85634SAl Viro err = lookup_last(nd); 2010574197e0SAl Viro put_link(nd, &link, cookie); 2011bd92d7feSAl Viro } 2012bd92d7feSAl Viro } 2013ee0827cdSAl Viro 20149f1fafeeSAl Viro if (!err) 20159f1fafeeSAl Viro err = complete_walk(nd); 2016bd92d7feSAl Viro 2017bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 201844b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 2019bd92d7feSAl Viro path_put(&nd->path); 2020bd23a539SAl Viro err = -ENOTDIR; 2021bd92d7feSAl Viro } 2022bd92d7feSAl Viro } 202316c2cd71SAl Viro 2024893b7775SAl Viro path_cleanup(nd); 2025bd92d7feSAl Viro return err; 202631e6b01fSNick Piggin } 202731e6b01fSNick Piggin 2028873f1eedSJeff Layton static int filename_lookup(int dfd, struct filename *name, 2029873f1eedSJeff Layton unsigned int flags, struct nameidata *nd) 2030873f1eedSJeff Layton { 20315eb6b495SAl Viro int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 2032873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 20335eb6b495SAl Viro retval = path_lookupat(dfd, name, flags, nd); 2034873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 20355eb6b495SAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 2036873f1eedSJeff Layton 2037873f1eedSJeff Layton if (likely(!retval)) 2038adb5c247SJeff Layton audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); 2039873f1eedSJeff Layton return retval; 2040873f1eedSJeff Layton } 2041873f1eedSJeff Layton 204279714f72SAl Viro /* does lookup, returns the object with parent locked */ 204379714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 20445590ff0dSUlrich Drepper { 204551689104SPaul Moore struct filename *filename = getname_kernel(name); 204679714f72SAl Viro struct nameidata nd; 204779714f72SAl Viro struct dentry *d; 204851689104SPaul Moore int err; 204951689104SPaul Moore 205051689104SPaul Moore if (IS_ERR(filename)) 205151689104SPaul Moore return ERR_CAST(filename); 205251689104SPaul Moore 205351689104SPaul Moore err = filename_lookup(AT_FDCWD, filename, LOOKUP_PARENT, &nd); 205451689104SPaul Moore if (err) { 205551689104SPaul Moore d = ERR_PTR(err); 205651689104SPaul Moore goto out; 205751689104SPaul Moore } 205879714f72SAl Viro if (nd.last_type != LAST_NORM) { 205979714f72SAl Viro path_put(&nd.path); 206051689104SPaul Moore d = ERR_PTR(-EINVAL); 206151689104SPaul Moore goto out; 206279714f72SAl Viro } 206379714f72SAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 20641e0ea001SAl Viro d = __lookup_hash(&nd.last, nd.path.dentry, 0); 206579714f72SAl Viro if (IS_ERR(d)) { 206679714f72SAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 206779714f72SAl Viro path_put(&nd.path); 206851689104SPaul Moore goto out; 206979714f72SAl Viro } 207079714f72SAl Viro *path = nd.path; 207151689104SPaul Moore out: 207251689104SPaul Moore putname(filename); 207379714f72SAl Viro return d; 20745590ff0dSUlrich Drepper } 20755590ff0dSUlrich Drepper 2076d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2077d1811465SAl Viro { 2078d1811465SAl Viro struct nameidata nd; 207974eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 208074eb8cc5SAl Viro int res = PTR_ERR(filename); 208174eb8cc5SAl Viro 208274eb8cc5SAl Viro if (!IS_ERR(filename)) { 208374eb8cc5SAl Viro res = filename_lookup(AT_FDCWD, filename, flags, &nd); 208474eb8cc5SAl Viro putname(filename); 2085d1811465SAl Viro if (!res) 2086d1811465SAl Viro *path = nd.path; 208774eb8cc5SAl Viro } 2088d1811465SAl Viro return res; 2089d1811465SAl Viro } 20904d359507SAl Viro EXPORT_SYMBOL(kern_path); 2091d1811465SAl Viro 209216f18200SJosef 'Jeff' Sipek /** 209316f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 209416f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 209516f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 209616f18200SJosef 'Jeff' Sipek * @name: pointer to file name 209716f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2098e0a01249SAl Viro * @path: pointer to struct path to fill 209916f18200SJosef 'Jeff' Sipek */ 210016f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 210116f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2102e0a01249SAl Viro struct path *path) 210316f18200SJosef 'Jeff' Sipek { 210474eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 210574eb8cc5SAl Viro int err = PTR_ERR(filename); 210674eb8cc5SAl Viro 210774eb8cc5SAl Viro BUG_ON(flags & LOOKUP_PARENT); 210874eb8cc5SAl Viro 210974eb8cc5SAl Viro /* the first argument of filename_lookup() is ignored with LOOKUP_ROOT */ 211074eb8cc5SAl Viro if (!IS_ERR(filename)) { 2111e0a01249SAl Viro struct nameidata nd; 2112e0a01249SAl Viro nd.root.dentry = dentry; 2113e0a01249SAl Viro nd.root.mnt = mnt; 211474eb8cc5SAl Viro err = filename_lookup(AT_FDCWD, filename, 211574eb8cc5SAl Viro flags | LOOKUP_ROOT, &nd); 2116e0a01249SAl Viro if (!err) 2117e0a01249SAl Viro *path = nd.path; 211874eb8cc5SAl Viro putname(filename); 211974eb8cc5SAl Viro } 2120e0a01249SAl Viro return err; 212116f18200SJosef 'Jeff' Sipek } 21224d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 212316f18200SJosef 'Jeff' Sipek 2124eead1911SChristoph Hellwig /** 2125a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2126eead1911SChristoph Hellwig * @name: pathname component to lookup 2127eead1911SChristoph Hellwig * @base: base directory to lookup from 2128eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2129eead1911SChristoph Hellwig * 2130a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 21319e7543e9SAl Viro * not be called by generic code. 2132eead1911SChristoph Hellwig */ 2133057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2134057f6c01SJames Morris { 2135057f6c01SJames Morris struct qstr this; 21366a96ba54SAl Viro unsigned int c; 2137cda309deSMiklos Szeredi int err; 2138057f6c01SJames Morris 21392f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 21402f9092e1SDavid Woodhouse 21416a96ba54SAl Viro this.name = name; 21426a96ba54SAl Viro this.len = len; 21430145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 21446a96ba54SAl Viro if (!len) 21456a96ba54SAl Viro return ERR_PTR(-EACCES); 21466a96ba54SAl Viro 214721d8a15aSAl Viro if (unlikely(name[0] == '.')) { 214821d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 214921d8a15aSAl Viro return ERR_PTR(-EACCES); 215021d8a15aSAl Viro } 215121d8a15aSAl Viro 21526a96ba54SAl Viro while (len--) { 21536a96ba54SAl Viro c = *(const unsigned char *)name++; 21546a96ba54SAl Viro if (c == '/' || c == '\0') 21556a96ba54SAl Viro return ERR_PTR(-EACCES); 21566a96ba54SAl Viro } 21575a202bcdSAl Viro /* 21585a202bcdSAl Viro * See if the low-level filesystem might want 21595a202bcdSAl Viro * to use its own hash.. 21605a202bcdSAl Viro */ 21615a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2162da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 21635a202bcdSAl Viro if (err < 0) 21645a202bcdSAl Viro return ERR_PTR(err); 21655a202bcdSAl Viro } 2166eead1911SChristoph Hellwig 2167cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2168cda309deSMiklos Szeredi if (err) 2169cda309deSMiklos Szeredi return ERR_PTR(err); 2170cda309deSMiklos Szeredi 217172bd866aSAl Viro return __lookup_hash(&this, base, 0); 2172057f6c01SJames Morris } 21734d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2174057f6c01SJames Morris 21751fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 21761fa1e7f6SAndy Whitcroft struct path *path, int *empty) 21771da177e4SLinus Torvalds { 21782d8f3038SAl Viro struct nameidata nd; 217991a27b2aSJeff Layton struct filename *tmp = getname_flags(name, flags, empty); 21801da177e4SLinus Torvalds int err = PTR_ERR(tmp); 21811da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 21822d8f3038SAl Viro 21832d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 21842d8f3038SAl Viro 2185873f1eedSJeff Layton err = filename_lookup(dfd, tmp, flags, &nd); 21861da177e4SLinus Torvalds putname(tmp); 21872d8f3038SAl Viro if (!err) 21882d8f3038SAl Viro *path = nd.path; 21891da177e4SLinus Torvalds } 21901da177e4SLinus Torvalds return err; 21911da177e4SLinus Torvalds } 21921da177e4SLinus Torvalds 21931fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 21941fa1e7f6SAndy Whitcroft struct path *path) 21951fa1e7f6SAndy Whitcroft { 2196f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 21971fa1e7f6SAndy Whitcroft } 21984d359507SAl Viro EXPORT_SYMBOL(user_path_at); 21991fa1e7f6SAndy Whitcroft 2200873f1eedSJeff Layton /* 2201873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2202873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2203873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2204873f1eedSJeff Layton * path-walking is complete. 2205873f1eedSJeff Layton */ 220691a27b2aSJeff Layton static struct filename * 2207f5beed75SAl Viro user_path_parent(int dfd, const char __user *path, 2208f5beed75SAl Viro struct path *parent, 2209f5beed75SAl Viro struct qstr *last, 2210f5beed75SAl Viro int *type, 22119e790bd6SJeff Layton unsigned int flags) 22122ad94ae6SAl Viro { 2213f5beed75SAl Viro struct nameidata nd; 221491a27b2aSJeff Layton struct filename *s = getname(path); 22152ad94ae6SAl Viro int error; 22162ad94ae6SAl Viro 22179e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 22189e790bd6SJeff Layton flags &= LOOKUP_REVAL; 22199e790bd6SJeff Layton 22202ad94ae6SAl Viro if (IS_ERR(s)) 222191a27b2aSJeff Layton return s; 22222ad94ae6SAl Viro 2223f5beed75SAl Viro error = filename_lookup(dfd, s, flags | LOOKUP_PARENT, &nd); 222491a27b2aSJeff Layton if (error) { 22252ad94ae6SAl Viro putname(s); 222691a27b2aSJeff Layton return ERR_PTR(error); 222791a27b2aSJeff Layton } 2228f5beed75SAl Viro *parent = nd.path; 2229f5beed75SAl Viro *last = nd.last; 2230f5beed75SAl Viro *type = nd.last_type; 22312ad94ae6SAl Viro 223291a27b2aSJeff Layton return s; 22332ad94ae6SAl Viro } 22342ad94ae6SAl Viro 22358033426eSJeff Layton /** 2236197df04cSAl Viro * mountpoint_last - look up last component for umount 22378033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 22388033426eSJeff Layton * @path: pointer to container for result 22398033426eSJeff Layton * 22408033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 22418033426eSJeff Layton * need to resolve the path without doing any revalidation. 22428033426eSJeff Layton * 22438033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 22448033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 22458033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 22468033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 22478033426eSJeff Layton * bogus and it doesn't exist. 22488033426eSJeff Layton * 22498033426eSJeff Layton * Returns: 22508033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 22518033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 22528033426eSJeff Layton * put in this case. 22538033426eSJeff Layton * 22548033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 22558033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 22568033426eSJeff Layton * The nd->path reference will also be put. 22578033426eSJeff Layton * 22588033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 22598033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 22608033426eSJeff Layton * to the link, and nd->path will *not* be put. 22618033426eSJeff Layton */ 22628033426eSJeff Layton static int 2263197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 22648033426eSJeff Layton { 22658033426eSJeff Layton int error = 0; 22668033426eSJeff Layton struct dentry *dentry; 22678033426eSJeff Layton struct dentry *dir = nd->path.dentry; 22688033426eSJeff Layton 226935759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 227035759521SAl Viro if (nd->flags & LOOKUP_RCU) { 227135759521SAl Viro if (unlazy_walk(nd, NULL)) { 22728033426eSJeff Layton error = -ECHILD; 227335759521SAl Viro goto out; 227435759521SAl Viro } 22758033426eSJeff Layton } 22768033426eSJeff Layton 22778033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 22788033426eSJeff Layton 22798033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 22808033426eSJeff Layton error = handle_dots(nd, nd->last_type); 228135759521SAl Viro if (error) 228235759521SAl Viro goto out; 22838033426eSJeff Layton dentry = dget(nd->path.dentry); 228435759521SAl Viro goto done; 22858033426eSJeff Layton } 22868033426eSJeff Layton 22878033426eSJeff Layton mutex_lock(&dir->d_inode->i_mutex); 22888033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 22898033426eSJeff Layton if (!dentry) { 22908033426eSJeff Layton /* 22918033426eSJeff Layton * No cached dentry. Mounted dentries are pinned in the cache, 22928033426eSJeff Layton * so that means that this dentry is probably a symlink or the 22938033426eSJeff Layton * path doesn't actually point to a mounted dentry. 22948033426eSJeff Layton */ 22958033426eSJeff Layton dentry = d_alloc(dir, &nd->last); 22968033426eSJeff Layton if (!dentry) { 22978033426eSJeff Layton error = -ENOMEM; 2298bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 229935759521SAl Viro goto out; 23008033426eSJeff Layton } 230135759521SAl Viro dentry = lookup_real(dir->d_inode, dentry, nd->flags); 230235759521SAl Viro error = PTR_ERR(dentry); 2303bcceeebaSDave Jones if (IS_ERR(dentry)) { 2304bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 230535759521SAl Viro goto out; 23068033426eSJeff Layton } 2307bcceeebaSDave Jones } 23088033426eSJeff Layton mutex_unlock(&dir->d_inode->i_mutex); 23098033426eSJeff Layton 231035759521SAl Viro done: 2311698934dfSDavid Howells if (d_is_negative(dentry)) { 23128033426eSJeff Layton error = -ENOENT; 23138033426eSJeff Layton dput(dentry); 231435759521SAl Viro goto out; 231535759521SAl Viro } 23168033426eSJeff Layton path->dentry = dentry; 2317295dc39dSVasily Averin path->mnt = nd->path.mnt; 2318caa85634SAl Viro if (should_follow_link(dentry, nd->flags & LOOKUP_FOLLOW)) { 2319caa85634SAl Viro nd->link = *path; 23208033426eSJeff Layton return 1; 2321caa85634SAl Viro } 2322295dc39dSVasily Averin mntget(path->mnt); 23238033426eSJeff Layton follow_mount(path); 232435759521SAl Viro error = 0; 232535759521SAl Viro out: 23268033426eSJeff Layton terminate_walk(nd); 23278033426eSJeff Layton return error; 23288033426eSJeff Layton } 23298033426eSJeff Layton 23308033426eSJeff Layton /** 2331197df04cSAl Viro * path_mountpoint - look up a path to be umounted 23328033426eSJeff Layton * @dfd: directory file descriptor to start walk from 23338033426eSJeff Layton * @name: full pathname to walk 2334606d6fe3SRandy Dunlap * @path: pointer to container for result 23358033426eSJeff Layton * @flags: lookup flags 23368033426eSJeff Layton * 23378033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2338606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 23398033426eSJeff Layton */ 23408033426eSJeff Layton static int 2341668696dcSAl Viro path_mountpoint(int dfd, const struct filename *name, struct path *path, 234246afd6f6SAl Viro struct nameidata *nd, unsigned int flags) 23438033426eSJeff Layton { 234446afd6f6SAl Viro int err = path_init(dfd, name, flags, nd); 23458033426eSJeff Layton if (unlikely(err)) 2346115cbfdcSAl Viro goto out; 23478033426eSJeff Layton 234846afd6f6SAl Viro err = mountpoint_last(nd, path); 23498033426eSJeff Layton while (err > 0) { 23508033426eSJeff Layton void *cookie; 23518033426eSJeff Layton struct path link = *path; 235295fa25d9SAl Viro err = trailing_symlink(&link, nd, &cookie); 23538033426eSJeff Layton if (err) 23548033426eSJeff Layton break; 235546afd6f6SAl Viro err = mountpoint_last(nd, path); 235646afd6f6SAl Viro put_link(nd, &link, cookie); 23578033426eSJeff Layton } 23588033426eSJeff Layton out: 235946afd6f6SAl Viro path_cleanup(nd); 23608033426eSJeff Layton return err; 23618033426eSJeff Layton } 23628033426eSJeff Layton 23632d864651SAl Viro static int 2364668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 23652d864651SAl Viro unsigned int flags) 23662d864651SAl Viro { 236746afd6f6SAl Viro struct nameidata nd; 2368cbaab2dbSAl Viro int error; 2369668696dcSAl Viro if (IS_ERR(name)) 2370668696dcSAl Viro return PTR_ERR(name); 237146afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_RCU); 23722d864651SAl Viro if (unlikely(error == -ECHILD)) 237346afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags); 23742d864651SAl Viro if (unlikely(error == -ESTALE)) 237546afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_REVAL); 23762d864651SAl Viro if (likely(!error)) 2377668696dcSAl Viro audit_inode(name, path->dentry, 0); 2378668696dcSAl Viro putname(name); 23792d864651SAl Viro return error; 23802d864651SAl Viro } 23812d864651SAl Viro 23828033426eSJeff Layton /** 2383197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 23848033426eSJeff Layton * @dfd: directory file descriptor 23858033426eSJeff Layton * @name: pathname from userland 23868033426eSJeff Layton * @flags: lookup flags 23878033426eSJeff Layton * @path: pointer to container to hold result 23888033426eSJeff Layton * 23898033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 23908033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 23918033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 23928033426eSJeff Layton * and avoid revalidating the last component. 23938033426eSJeff Layton * 23948033426eSJeff Layton * Returns 0 and populates "path" on success. 23958033426eSJeff Layton */ 23968033426eSJeff Layton int 2397197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 23988033426eSJeff Layton struct path *path) 23998033426eSJeff Layton { 2400cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 24018033426eSJeff Layton } 24028033426eSJeff Layton 24032d864651SAl Viro int 24042d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 24052d864651SAl Viro unsigned int flags) 24062d864651SAl Viro { 2407cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 24082d864651SAl Viro } 24092d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 24102d864651SAl Viro 2411cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 24121da177e4SLinus Torvalds { 24138e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2414da9592edSDavid Howells 24158e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 24161da177e4SLinus Torvalds return 0; 24178e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 24181da177e4SLinus Torvalds return 0; 241923adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 24201da177e4SLinus Torvalds } 2421cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 24221da177e4SLinus Torvalds 24231da177e4SLinus Torvalds /* 24241da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 24251da177e4SLinus Torvalds * whether the type of victim is right. 24261da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 24271da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 24281da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 24291da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 24301da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 24311da177e4SLinus Torvalds * a. be owner of dir, or 24321da177e4SLinus Torvalds * b. be owner of victim, or 24331da177e4SLinus Torvalds * c. have CAP_FOWNER capability 24341da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 24351da177e4SLinus Torvalds * links pointing to it. 24361da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 24371da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 24381da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 24391da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 24401da177e4SLinus Torvalds * nfs_async_unlink(). 24411da177e4SLinus Torvalds */ 2442b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 24431da177e4SLinus Torvalds { 2444b18825a7SDavid Howells struct inode *inode = victim->d_inode; 24451da177e4SLinus Torvalds int error; 24461da177e4SLinus Torvalds 2447b18825a7SDavid Howells if (d_is_negative(victim)) 24481da177e4SLinus Torvalds return -ENOENT; 2449b18825a7SDavid Howells BUG_ON(!inode); 24501da177e4SLinus Torvalds 24511da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 24524fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 24531da177e4SLinus Torvalds 2454f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 24551da177e4SLinus Torvalds if (error) 24561da177e4SLinus Torvalds return error; 24571da177e4SLinus Torvalds if (IS_APPEND(dir)) 24581da177e4SLinus Torvalds return -EPERM; 2459b18825a7SDavid Howells 2460b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2461b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 24621da177e4SLinus Torvalds return -EPERM; 24631da177e4SLinus Torvalds if (isdir) { 246444b1d530SMiklos Szeredi if (!d_is_dir(victim)) 24651da177e4SLinus Torvalds return -ENOTDIR; 24661da177e4SLinus Torvalds if (IS_ROOT(victim)) 24671da177e4SLinus Torvalds return -EBUSY; 246844b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 24691da177e4SLinus Torvalds return -EISDIR; 24701da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 24711da177e4SLinus Torvalds return -ENOENT; 24721da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 24731da177e4SLinus Torvalds return -EBUSY; 24741da177e4SLinus Torvalds return 0; 24751da177e4SLinus Torvalds } 24761da177e4SLinus Torvalds 24771da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 24781da177e4SLinus Torvalds * dir. 24791da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 24801da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 24811da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 24821da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 24831da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 24841da177e4SLinus Torvalds */ 2485a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 24861da177e4SLinus Torvalds { 248714e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 24881da177e4SLinus Torvalds if (child->d_inode) 24891da177e4SLinus Torvalds return -EEXIST; 24901da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 24911da177e4SLinus Torvalds return -ENOENT; 2492f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 24931da177e4SLinus Torvalds } 24941da177e4SLinus Torvalds 24951da177e4SLinus Torvalds /* 24961da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 24971da177e4SLinus Torvalds */ 24981da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 24991da177e4SLinus Torvalds { 25001da177e4SLinus Torvalds struct dentry *p; 25011da177e4SLinus Torvalds 25021da177e4SLinus Torvalds if (p1 == p2) { 2503f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 25041da177e4SLinus Torvalds return NULL; 25051da177e4SLinus Torvalds } 25061da177e4SLinus Torvalds 2507a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25081da177e4SLinus Torvalds 2509e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2510e2761a11SOGAWA Hirofumi if (p) { 2511f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2512f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 25131da177e4SLinus Torvalds return p; 25141da177e4SLinus Torvalds } 25151da177e4SLinus Torvalds 2516e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2517e2761a11SOGAWA Hirofumi if (p) { 2518f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2519f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 25201da177e4SLinus Torvalds return p; 25211da177e4SLinus Torvalds } 25221da177e4SLinus Torvalds 2523f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2524d1b72cc6SMiklos Szeredi mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); 25251da177e4SLinus Torvalds return NULL; 25261da177e4SLinus Torvalds } 25274d359507SAl Viro EXPORT_SYMBOL(lock_rename); 25281da177e4SLinus Torvalds 25291da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 25301da177e4SLinus Torvalds { 25311b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 25321da177e4SLinus Torvalds if (p1 != p2) { 25331b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2534a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25351da177e4SLinus Torvalds } 25361da177e4SLinus Torvalds } 25374d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 25381da177e4SLinus Torvalds 25394acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2540312b63fbSAl Viro bool want_excl) 25411da177e4SLinus Torvalds { 2542a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 25431da177e4SLinus Torvalds if (error) 25441da177e4SLinus Torvalds return error; 25451da177e4SLinus Torvalds 2546acfa4380SAl Viro if (!dir->i_op->create) 25471da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 25481da177e4SLinus Torvalds mode &= S_IALLUGO; 25491da177e4SLinus Torvalds mode |= S_IFREG; 25501da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 25511da177e4SLinus Torvalds if (error) 25521da177e4SLinus Torvalds return error; 2553312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2554a74574aaSStephen Smalley if (!error) 2555f38aa942SAmy Griffis fsnotify_create(dir, dentry); 25561da177e4SLinus Torvalds return error; 25571da177e4SLinus Torvalds } 25584d359507SAl Viro EXPORT_SYMBOL(vfs_create); 25591da177e4SLinus Torvalds 256073d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 25611da177e4SLinus Torvalds { 25623fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 25631da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 25641da177e4SLinus Torvalds int error; 25651da177e4SLinus Torvalds 2566bcda7652SAl Viro /* O_PATH? */ 2567bcda7652SAl Viro if (!acc_mode) 2568bcda7652SAl Viro return 0; 2569bcda7652SAl Viro 25701da177e4SLinus Torvalds if (!inode) 25711da177e4SLinus Torvalds return -ENOENT; 25721da177e4SLinus Torvalds 2573c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2574c8fe8f30SChristoph Hellwig case S_IFLNK: 25751da177e4SLinus Torvalds return -ELOOP; 2576c8fe8f30SChristoph Hellwig case S_IFDIR: 2577c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 25781da177e4SLinus Torvalds return -EISDIR; 2579c8fe8f30SChristoph Hellwig break; 2580c8fe8f30SChristoph Hellwig case S_IFBLK: 2581c8fe8f30SChristoph Hellwig case S_IFCHR: 25823fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 25831da177e4SLinus Torvalds return -EACCES; 2584c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2585c8fe8f30SChristoph Hellwig case S_IFIFO: 2586c8fe8f30SChristoph Hellwig case S_IFSOCK: 25871da177e4SLinus Torvalds flag &= ~O_TRUNC; 2588c8fe8f30SChristoph Hellwig break; 25894a3fd211SDave Hansen } 2590b41572e9SDave Hansen 25913fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2592b41572e9SDave Hansen if (error) 2593b41572e9SDave Hansen return error; 25946146f0d5SMimi Zohar 25951da177e4SLinus Torvalds /* 25961da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 25971da177e4SLinus Torvalds */ 25981da177e4SLinus Torvalds if (IS_APPEND(inode)) { 25998737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 26007715b521SAl Viro return -EPERM; 26011da177e4SLinus Torvalds if (flag & O_TRUNC) 26027715b521SAl Viro return -EPERM; 26031da177e4SLinus Torvalds } 26041da177e4SLinus Torvalds 26051da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 26062e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 26077715b521SAl Viro return -EPERM; 26081da177e4SLinus Torvalds 2609f3c7691eSJ. Bruce Fields return 0; 26107715b521SAl Viro } 26117715b521SAl Viro 2612e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 26137715b521SAl Viro { 2614e1181ee6SJeff Layton struct path *path = &filp->f_path; 26157715b521SAl Viro struct inode *inode = path->dentry->d_inode; 26167715b521SAl Viro int error = get_write_access(inode); 26171da177e4SLinus Torvalds if (error) 26187715b521SAl Viro return error; 26191da177e4SLinus Torvalds /* 26201da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 26211da177e4SLinus Torvalds */ 2622d7a06983SJeff Layton error = locks_verify_locked(filp); 2623be6d3e56SKentaro Takeda if (!error) 2624ea0d3ab2STetsuo Handa error = security_path_truncate(path); 26251da177e4SLinus Torvalds if (!error) { 26267715b521SAl Viro error = do_truncate(path->dentry, 0, 2627d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2628e1181ee6SJeff Layton filp); 26291da177e4SLinus Torvalds } 26301da177e4SLinus Torvalds put_write_access(inode); 2631acd0c935SMimi Zohar return error; 26321da177e4SLinus Torvalds } 26331da177e4SLinus Torvalds 2634d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2635d57999e1SDave Hansen { 26368a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 26378a5e929dSAl Viro flag--; 2638d57999e1SDave Hansen return flag; 2639d57999e1SDave Hansen } 2640d57999e1SDave Hansen 2641d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2642d18e9008SMiklos Szeredi { 2643d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2644d18e9008SMiklos Szeredi if (error) 2645d18e9008SMiklos Szeredi return error; 2646d18e9008SMiklos Szeredi 2647d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2648d18e9008SMiklos Szeredi if (error) 2649d18e9008SMiklos Szeredi return error; 2650d18e9008SMiklos Szeredi 2651d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2652d18e9008SMiklos Szeredi } 2653d18e9008SMiklos Szeredi 26541acf0af9SDavid Howells /* 26551acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 26561acf0af9SDavid Howells * dentry. 26571acf0af9SDavid Howells * 26581acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 26591acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 26601acf0af9SDavid Howells * 26611acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 26621acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 26631acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 26641acf0af9SDavid Howells * 26651acf0af9SDavid Howells * Returns an error code otherwise. 26661acf0af9SDavid Howells */ 26672675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 266830d90494SAl Viro struct path *path, struct file *file, 2669015c3bbcSMiklos Szeredi const struct open_flags *op, 267064894cf8SAl Viro bool got_write, bool need_lookup, 267147237687SAl Viro int *opened) 2672d18e9008SMiklos Szeredi { 2673d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2674d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2675d18e9008SMiklos Szeredi umode_t mode; 2676d18e9008SMiklos Szeredi int error; 2677d18e9008SMiklos Szeredi int acc_mode; 2678d18e9008SMiklos Szeredi int create_error = 0; 2679d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2680116cc022SMiklos Szeredi bool excl; 2681d18e9008SMiklos Szeredi 2682d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2683d18e9008SMiklos Szeredi 2684d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2685d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 26862675a4ebSAl Viro error = -ENOENT; 2687d18e9008SMiklos Szeredi goto out; 2688d18e9008SMiklos Szeredi } 2689d18e9008SMiklos Szeredi 269062b259d8SMiklos Szeredi mode = op->mode; 2691d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2692d18e9008SMiklos Szeredi mode &= ~current_umask(); 2693d18e9008SMiklos Szeredi 2694116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2695116cc022SMiklos Szeredi if (excl) 2696d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2697d18e9008SMiklos Szeredi 2698d18e9008SMiklos Szeredi /* 2699d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2700d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2701d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2702d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2703d18e9008SMiklos Szeredi * 2704d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2705d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2706d18e9008SMiklos Szeredi */ 270764894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 270864894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 270964894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2710d18e9008SMiklos Szeredi /* 2711d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2712d18e9008SMiklos Szeredi * back to lookup + open 2713d18e9008SMiklos Szeredi */ 2714d18e9008SMiklos Szeredi goto no_open; 2715d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2716d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 271764894cf8SAl Viro create_error = -EROFS; 2718d18e9008SMiklos Szeredi goto no_open; 2719d18e9008SMiklos Szeredi } else { 2720d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 272164894cf8SAl Viro create_error = -EROFS; 2722d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2723d18e9008SMiklos Szeredi } 2724d18e9008SMiklos Szeredi } 2725d18e9008SMiklos Szeredi 2726d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 272738227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2728d18e9008SMiklos Szeredi if (error) { 2729d18e9008SMiklos Szeredi create_error = error; 2730d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2731d18e9008SMiklos Szeredi goto no_open; 2732d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2733d18e9008SMiklos Szeredi } 2734d18e9008SMiklos Szeredi } 2735d18e9008SMiklos Szeredi 2736d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2737d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2738d18e9008SMiklos Szeredi 273930d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 274030d90494SAl Viro file->f_path.mnt = nd->path.mnt; 274130d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 274247237687SAl Viro opened); 2743d9585277SAl Viro if (error < 0) { 2744d9585277SAl Viro if (create_error && error == -ENOENT) 2745d9585277SAl Viro error = create_error; 2746d18e9008SMiklos Szeredi goto out; 2747d18e9008SMiklos Szeredi } 2748d18e9008SMiklos Szeredi 2749d9585277SAl Viro if (error) { /* returned 1, that is */ 275030d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 27512675a4ebSAl Viro error = -EIO; 2752d18e9008SMiklos Szeredi goto out; 2753d18e9008SMiklos Szeredi } 275430d90494SAl Viro if (file->f_path.dentry) { 2755d18e9008SMiklos Szeredi dput(dentry); 275630d90494SAl Viro dentry = file->f_path.dentry; 2757d18e9008SMiklos Szeredi } 275803da633aSAl Viro if (*opened & FILE_CREATED) 275903da633aSAl Viro fsnotify_create(dir, dentry); 276003da633aSAl Viro if (!dentry->d_inode) { 276103da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 276203da633aSAl Viro if (create_error) { 276362b2ce96SSage Weil error = create_error; 276462b2ce96SSage Weil goto out; 276562b2ce96SSage Weil } 276603da633aSAl Viro } else { 276703da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 276803da633aSAl Viro error = -EEXIST; 276903da633aSAl Viro goto out; 277003da633aSAl Viro } 277103da633aSAl Viro } 2772d18e9008SMiklos Szeredi goto looked_up; 2773d18e9008SMiklos Szeredi } 2774d18e9008SMiklos Szeredi 2775d18e9008SMiklos Szeredi /* 2776d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2777d18e9008SMiklos Szeredi * here. 2778d18e9008SMiklos Szeredi */ 277903da633aSAl Viro acc_mode = op->acc_mode; 278003da633aSAl Viro if (*opened & FILE_CREATED) { 278103da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 278203da633aSAl Viro fsnotify_create(dir, dentry); 278303da633aSAl Viro acc_mode = MAY_OPEN; 278403da633aSAl Viro } 27852675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 27862675a4ebSAl Viro if (error) 27872675a4ebSAl Viro fput(file); 2788d18e9008SMiklos Szeredi 2789d18e9008SMiklos Szeredi out: 2790d18e9008SMiklos Szeredi dput(dentry); 27912675a4ebSAl Viro return error; 2792d18e9008SMiklos Szeredi 2793d18e9008SMiklos Szeredi no_open: 2794d18e9008SMiklos Szeredi if (need_lookup) { 279572bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2796d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 27972675a4ebSAl Viro return PTR_ERR(dentry); 2798d18e9008SMiklos Szeredi 2799d18e9008SMiklos Szeredi if (create_error) { 2800d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2801d18e9008SMiklos Szeredi 28022675a4ebSAl Viro error = create_error; 2803d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2804d18e9008SMiklos Szeredi if (!dentry->d_inode) 2805d18e9008SMiklos Szeredi goto out; 2806d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2807d18e9008SMiklos Szeredi goto out; 2808d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2809e36cb0b8SDavid Howells d_is_reg(dentry)) { 2810d18e9008SMiklos Szeredi goto out; 2811d18e9008SMiklos Szeredi } 2812d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2813d18e9008SMiklos Szeredi } 2814d18e9008SMiklos Szeredi } 2815d18e9008SMiklos Szeredi looked_up: 2816d18e9008SMiklos Szeredi path->dentry = dentry; 2817d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 28182675a4ebSAl Viro return 1; 2819d18e9008SMiklos Szeredi } 2820d18e9008SMiklos Szeredi 282131e6b01fSNick Piggin /* 28221acf0af9SDavid Howells * Look up and maybe create and open the last component. 2823d58ffd35SMiklos Szeredi * 2824d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2825d58ffd35SMiklos Szeredi * 28261acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 28271acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 28281acf0af9SDavid Howells * 28291acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 28301acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 28311acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 28321acf0af9SDavid Howells * specified then a negative dentry may be returned. 28331acf0af9SDavid Howells * 28341acf0af9SDavid Howells * An error code is returned otherwise. 28351acf0af9SDavid Howells * 28361acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 28371acf0af9SDavid Howells * cleared otherwise prior to returning. 2838d58ffd35SMiklos Szeredi */ 28392675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 284030d90494SAl Viro struct file *file, 2841d58ffd35SMiklos Szeredi const struct open_flags *op, 284264894cf8SAl Viro bool got_write, int *opened) 2843d58ffd35SMiklos Szeredi { 2844d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 284554ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2846d58ffd35SMiklos Szeredi struct dentry *dentry; 2847d58ffd35SMiklos Szeredi int error; 284854ef4872SMiklos Szeredi bool need_lookup; 2849d58ffd35SMiklos Szeredi 285047237687SAl Viro *opened &= ~FILE_CREATED; 2851201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2852d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 28532675a4ebSAl Viro return PTR_ERR(dentry); 2854d58ffd35SMiklos Szeredi 2855d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2856d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2857d18e9008SMiklos Szeredi goto out_no_open; 2858d18e9008SMiklos Szeredi 2859d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 286064894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 286147237687SAl Viro need_lookup, opened); 2862d18e9008SMiklos Szeredi } 2863d18e9008SMiklos Szeredi 286454ef4872SMiklos Szeredi if (need_lookup) { 286554ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 286654ef4872SMiklos Szeredi 286772bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 286854ef4872SMiklos Szeredi if (IS_ERR(dentry)) 28692675a4ebSAl Viro return PTR_ERR(dentry); 287054ef4872SMiklos Szeredi } 287154ef4872SMiklos Szeredi 2872d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2873d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2874d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2875d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2876d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2877d58ffd35SMiklos Szeredi /* 2878d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2879d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2880d58ffd35SMiklos Szeredi * the time when the file is created and when 2881d58ffd35SMiklos Szeredi * a permanent write count is taken through 2882015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 2883d58ffd35SMiklos Szeredi */ 288464894cf8SAl Viro if (!got_write) { 288564894cf8SAl Viro error = -EROFS; 2886d58ffd35SMiklos Szeredi goto out_dput; 288764894cf8SAl Viro } 288847237687SAl Viro *opened |= FILE_CREATED; 2889d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2890d58ffd35SMiklos Szeredi if (error) 2891d58ffd35SMiklos Szeredi goto out_dput; 2892312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 2893312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 2894d58ffd35SMiklos Szeredi if (error) 2895d58ffd35SMiklos Szeredi goto out_dput; 2896d58ffd35SMiklos Szeredi } 2897d18e9008SMiklos Szeredi out_no_open: 2898d58ffd35SMiklos Szeredi path->dentry = dentry; 2899d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 29002675a4ebSAl Viro return 1; 2901d58ffd35SMiklos Szeredi 2902d58ffd35SMiklos Szeredi out_dput: 2903d58ffd35SMiklos Szeredi dput(dentry); 29042675a4ebSAl Viro return error; 2905d58ffd35SMiklos Szeredi } 2906d58ffd35SMiklos Szeredi 2907d58ffd35SMiklos Szeredi /* 2908fe2d35ffSAl Viro * Handle the last step of open() 290931e6b01fSNick Piggin */ 2910896475d5SAl Viro static int do_last(struct nameidata *nd, 291130d90494SAl Viro struct file *file, const struct open_flags *op, 2912669abf4eSJeff Layton int *opened, struct filename *name) 2913fb1cc555SAl Viro { 2914a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2915ca344a89SAl Viro int open_flag = op->open_flag; 291677d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 291764894cf8SAl Viro bool got_write = false; 2918bcda7652SAl Viro int acc_mode = op->acc_mode; 2919a1eb3315SMiklos Szeredi struct inode *inode; 292016b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 2921896475d5SAl Viro struct path path; 292216b1c1cdSMiklos Szeredi bool retried = false; 292316c2cd71SAl Viro int error; 2924fb1cc555SAl Viro 2925c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2926c3e380b0SAl Viro nd->flags |= op->intent; 2927c3e380b0SAl Viro 2928bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 2929fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2930fe2d35ffSAl Viro if (error) 29312675a4ebSAl Viro return error; 2932e83db167SMiklos Szeredi goto finish_open; 29331f36f774SAl Viro } 2934a2c36b45SAl Viro 2935ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2936fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2937fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2938fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2939896475d5SAl Viro error = lookup_fast(nd, &path, &inode); 294071574865SMiklos Szeredi if (likely(!error)) 294171574865SMiklos Szeredi goto finish_lookup; 294271574865SMiklos Szeredi 2943ce57dfc1SAl Viro if (error < 0) 29442675a4ebSAl Viro goto out; 2945a1eb3315SMiklos Szeredi 294637d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 2947b6183df7SMiklos Szeredi } else { 2948fe2d35ffSAl Viro /* create side of things */ 2949a3fbbde7SAl Viro /* 2950b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 2951b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 2952b6183df7SMiklos Szeredi * about to look up 2953a3fbbde7SAl Viro */ 29549f1fafeeSAl Viro error = complete_walk(nd); 29559f1fafeeSAl Viro if (error) 29562675a4ebSAl Viro return error; 2957fe2d35ffSAl Viro 295833e2208aSJeff Layton audit_inode(name, dir, LOOKUP_PARENT); 295916c2cd71SAl Viro error = -EISDIR; 29601f36f774SAl Viro /* trailing slashes? */ 296131e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 29622675a4ebSAl Viro goto out; 2963b6183df7SMiklos Szeredi } 29641f36f774SAl Viro 296516b1c1cdSMiklos Szeredi retry_lookup: 296664894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 296764894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 296864894cf8SAl Viro if (!error) 296964894cf8SAl Viro got_write = true; 297064894cf8SAl Viro /* 297164894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 297264894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 297364894cf8SAl Viro * dropping this one anyway. 297464894cf8SAl Viro */ 297564894cf8SAl Viro } 2976a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 2977896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 2978fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2979fb1cc555SAl Viro 29802675a4ebSAl Viro if (error <= 0) { 29812675a4ebSAl Viro if (error) 2982d58ffd35SMiklos Szeredi goto out; 29836c0d46c4SAl Viro 298447237687SAl Viro if ((*opened & FILE_CREATED) || 2985496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 298677d660a8SMiklos Szeredi will_truncate = false; 2987d18e9008SMiklos Szeredi 2988adb5c247SJeff Layton audit_inode(name, file->f_path.dentry, 0); 2989d18e9008SMiklos Szeredi goto opened; 2990d18e9008SMiklos Szeredi } 2991d18e9008SMiklos Szeredi 299247237687SAl Viro if (*opened & FILE_CREATED) { 29939b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 2994ca344a89SAl Viro open_flag &= ~O_TRUNC; 299577d660a8SMiklos Szeredi will_truncate = false; 2996bcda7652SAl Viro acc_mode = MAY_OPEN; 2997896475d5SAl Viro path_to_nameidata(&path, nd); 2998e83db167SMiklos Szeredi goto finish_open_created; 2999fb1cc555SAl Viro } 3000fb1cc555SAl Viro 3001fb1cc555SAl Viro /* 30023134f37eSJeff Layton * create/update audit record if it already exists. 3003fb1cc555SAl Viro */ 3004896475d5SAl Viro if (d_is_positive(path.dentry)) 3005896475d5SAl Viro audit_inode(name, path.dentry, 0); 3006fb1cc555SAl Viro 3007d18e9008SMiklos Szeredi /* 3008d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3009d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3010d18e9008SMiklos Szeredi * necessary...) 3011d18e9008SMiklos Szeredi */ 301264894cf8SAl Viro if (got_write) { 3013d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 301464894cf8SAl Viro got_write = false; 3015d18e9008SMiklos Szeredi } 3016d18e9008SMiklos Szeredi 3017fb1cc555SAl Viro error = -EEXIST; 3018f8310c59SAl Viro if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) 3019fb1cc555SAl Viro goto exit_dput; 3020fb1cc555SAl Viro 3021896475d5SAl Viro error = follow_managed(&path, nd->flags); 30229875cf80SDavid Howells if (error < 0) 3023fb1cc555SAl Viro goto exit_dput; 3024fb1cc555SAl Viro 3025a3fbbde7SAl Viro if (error) 3026a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 3027a3fbbde7SAl Viro 3028decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 3029896475d5SAl Viro inode = path.dentry->d_inode; 3030fb1cc555SAl Viro error = -ENOENT; 3031896475d5SAl Viro if (d_is_negative(path.dentry)) { 3032896475d5SAl Viro path_to_nameidata(&path, nd); 30332675a4ebSAl Viro goto out; 303454c33e7fSMiklos Szeredi } 3035766c4cbfSAl Viro finish_lookup: 3036896475d5SAl Viro if (should_follow_link(path.dentry, nd->flags & LOOKUP_FOLLOW)) { 3037d45ea867SMiklos Szeredi if (nd->flags & LOOKUP_RCU) { 3038896475d5SAl Viro if (unlikely(nd->path.mnt != path.mnt || 3039896475d5SAl Viro unlazy_walk(nd, path.dentry))) { 3040d45ea867SMiklos Szeredi error = -ECHILD; 30412675a4ebSAl Viro goto out; 3042d45ea867SMiklos Szeredi } 3043d45ea867SMiklos Szeredi } 3044896475d5SAl Viro BUG_ON(inode != path.dentry->d_inode); 3045896475d5SAl Viro nd->link = path; 30462675a4ebSAl Viro return 1; 3047d45ea867SMiklos Szeredi } 3048fb1cc555SAl Viro 3049896475d5SAl Viro if (unlikely(d_is_symlink(path.dentry)) && !(open_flag & O_PATH)) { 3050896475d5SAl Viro path_to_nameidata(&path, nd); 3051a5cfe2d5SAl Viro error = -ELOOP; 3052a5cfe2d5SAl Viro goto out; 3053a5cfe2d5SAl Viro } 3054a5cfe2d5SAl Viro 3055896475d5SAl Viro if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { 3056896475d5SAl Viro path_to_nameidata(&path, nd); 305716b1c1cdSMiklos Szeredi } else { 305816b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 3059896475d5SAl Viro save_parent.mnt = mntget(path.mnt); 3060896475d5SAl Viro nd->path.dentry = path.dentry; 306116b1c1cdSMiklos Szeredi 306216b1c1cdSMiklos Szeredi } 3063decf3400SMiklos Szeredi nd->inode = inode; 3064a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3065bc77daa7SAl Viro finish_open: 3066a3fbbde7SAl Viro error = complete_walk(nd); 306716b1c1cdSMiklos Szeredi if (error) { 306816b1c1cdSMiklos Szeredi path_put(&save_parent); 30692675a4ebSAl Viro return error; 307016b1c1cdSMiklos Szeredi } 3071bc77daa7SAl Viro audit_inode(name, nd->path.dentry, 0); 3072fb1cc555SAl Viro error = -EISDIR; 307344b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 30742675a4ebSAl Viro goto out; 3075af2f5542SMiklos Szeredi error = -ENOTDIR; 307644b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 30772675a4ebSAl Viro goto out; 30784bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 307977d660a8SMiklos Szeredi will_truncate = false; 30806c0d46c4SAl Viro 30810f9d1a10SAl Viro if (will_truncate) { 30820f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 30830f9d1a10SAl Viro if (error) 30842675a4ebSAl Viro goto out; 308564894cf8SAl Viro got_write = true; 30860f9d1a10SAl Viro } 3087e83db167SMiklos Szeredi finish_open_created: 3088bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3089ca344a89SAl Viro if (error) 30902675a4ebSAl Viro goto out; 30914aa7c634SMiklos Szeredi 30924aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 30934aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 30944aa7c634SMiklos Szeredi if (!error) { 30954aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 30964aa7c634SMiklos Szeredi } else { 309730d90494SAl Viro if (error == -EOPENSTALE) 3098f60dc3dbSMiklos Szeredi goto stale_open; 3099015c3bbcSMiklos Szeredi goto out; 3100f60dc3dbSMiklos Szeredi } 3101a8277b9bSMiklos Szeredi opened: 31022675a4ebSAl Viro error = open_check_o_direct(file); 3103015c3bbcSMiklos Szeredi if (error) 3104015c3bbcSMiklos Szeredi goto exit_fput; 31053034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3106aa4caadbSMiklos Szeredi if (error) 3107aa4caadbSMiklos Szeredi goto exit_fput; 3108aa4caadbSMiklos Szeredi 31090f9d1a10SAl Viro if (will_truncate) { 31102675a4ebSAl Viro error = handle_truncate(file); 3111aa4caadbSMiklos Szeredi if (error) 3112aa4caadbSMiklos Szeredi goto exit_fput; 31130f9d1a10SAl Viro } 3114ca344a89SAl Viro out: 311564894cf8SAl Viro if (got_write) 31160f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 311716b1c1cdSMiklos Szeredi path_put(&save_parent); 3118e276ae67SMiklos Szeredi terminate_walk(nd); 31192675a4ebSAl Viro return error; 3120fb1cc555SAl Viro 3121fb1cc555SAl Viro exit_dput: 3122896475d5SAl Viro path_put_conditional(&path, nd); 3123ca344a89SAl Viro goto out; 3124015c3bbcSMiklos Szeredi exit_fput: 31252675a4ebSAl Viro fput(file); 31262675a4ebSAl Viro goto out; 3127015c3bbcSMiklos Szeredi 3128f60dc3dbSMiklos Szeredi stale_open: 3129f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3130f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3131f60dc3dbSMiklos Szeredi goto out; 3132f60dc3dbSMiklos Szeredi 3133f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3134f60dc3dbSMiklos Szeredi path_put(&nd->path); 3135f60dc3dbSMiklos Szeredi nd->path = save_parent; 3136f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3137f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3138f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 313964894cf8SAl Viro if (got_write) { 3140f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 314164894cf8SAl Viro got_write = false; 3142f60dc3dbSMiklos Szeredi } 3143f60dc3dbSMiklos Szeredi retried = true; 3144f60dc3dbSMiklos Szeredi goto retry_lookup; 3145fb1cc555SAl Viro } 3146fb1cc555SAl Viro 314760545d0dSAl Viro static int do_tmpfile(int dfd, struct filename *pathname, 314860545d0dSAl Viro struct nameidata *nd, int flags, 314960545d0dSAl Viro const struct open_flags *op, 315060545d0dSAl Viro struct file *file, int *opened) 315160545d0dSAl Viro { 315260545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 315360545d0dSAl Viro struct dentry *dentry, *child; 315460545d0dSAl Viro struct inode *dir; 31555eb6b495SAl Viro int error = path_lookupat(dfd, pathname, 315660545d0dSAl Viro flags | LOOKUP_DIRECTORY, nd); 315760545d0dSAl Viro if (unlikely(error)) 315860545d0dSAl Viro return error; 315960545d0dSAl Viro error = mnt_want_write(nd->path.mnt); 316060545d0dSAl Viro if (unlikely(error)) 316160545d0dSAl Viro goto out; 316260545d0dSAl Viro /* we want directory to be writable */ 316360545d0dSAl Viro error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); 316460545d0dSAl Viro if (error) 316560545d0dSAl Viro goto out2; 316660545d0dSAl Viro dentry = nd->path.dentry; 316760545d0dSAl Viro dir = dentry->d_inode; 316860545d0dSAl Viro if (!dir->i_op->tmpfile) { 316960545d0dSAl Viro error = -EOPNOTSUPP; 317060545d0dSAl Viro goto out2; 317160545d0dSAl Viro } 317260545d0dSAl Viro child = d_alloc(dentry, &name); 317360545d0dSAl Viro if (unlikely(!child)) { 317460545d0dSAl Viro error = -ENOMEM; 317560545d0dSAl Viro goto out2; 317660545d0dSAl Viro } 317760545d0dSAl Viro nd->flags &= ~LOOKUP_DIRECTORY; 317860545d0dSAl Viro nd->flags |= op->intent; 317960545d0dSAl Viro dput(nd->path.dentry); 318060545d0dSAl Viro nd->path.dentry = child; 318160545d0dSAl Viro error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); 318260545d0dSAl Viro if (error) 318360545d0dSAl Viro goto out2; 318460545d0dSAl Viro audit_inode(pathname, nd->path.dentry, 0); 318569a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 318669a91c23SEric Rannaud error = may_open(&nd->path, MAY_OPEN, op->open_flag); 318760545d0dSAl Viro if (error) 318860545d0dSAl Viro goto out2; 318960545d0dSAl Viro file->f_path.mnt = nd->path.mnt; 319060545d0dSAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 319160545d0dSAl Viro if (error) 319260545d0dSAl Viro goto out2; 319360545d0dSAl Viro error = open_check_o_direct(file); 3194f4e0c30cSAl Viro if (error) { 319560545d0dSAl Viro fput(file); 3196f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3197f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3198f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3199f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3200f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3201f4e0c30cSAl Viro } 320260545d0dSAl Viro out2: 320360545d0dSAl Viro mnt_drop_write(nd->path.mnt); 320460545d0dSAl Viro out: 320560545d0dSAl Viro path_put(&nd->path); 320660545d0dSAl Viro return error; 320760545d0dSAl Viro } 320860545d0dSAl Viro 3209669abf4eSJeff Layton static struct file *path_openat(int dfd, struct filename *pathname, 321073d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 32111da177e4SLinus Torvalds { 321230d90494SAl Viro struct file *file; 321347237687SAl Viro int opened = 0; 321413aab428SAl Viro int error; 321531e6b01fSNick Piggin 321630d90494SAl Viro file = get_empty_filp(); 32171afc99beSAl Viro if (IS_ERR(file)) 32181afc99beSAl Viro return file; 321931e6b01fSNick Piggin 322030d90494SAl Viro file->f_flags = op->open_flag; 322131e6b01fSNick Piggin 3222bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 322360545d0dSAl Viro error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); 3224f15133dfSAl Viro goto out2; 322560545d0dSAl Viro } 322660545d0dSAl Viro 32276e8a1f87SAl Viro error = path_init(dfd, pathname, flags, nd); 322831e6b01fSNick Piggin if (unlikely(error)) 32292675a4ebSAl Viro goto out; 32301da177e4SLinus Torvalds 3231896475d5SAl Viro error = do_last(nd, file, op, &opened, pathname); 32322675a4ebSAl Viro while (unlikely(error > 0)) { /* trailing symlink */ 3233caa85634SAl Viro struct path link = nd->link; 3234def4af30SAl Viro void *cookie; 323573d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 323695fa25d9SAl Viro error = trailing_symlink(&link, nd, &cookie); 3237c3e380b0SAl Viro if (unlikely(error)) 32382675a4ebSAl Viro break; 3239896475d5SAl Viro error = do_last(nd, file, op, &opened, pathname); 3240574197e0SAl Viro put_link(nd, &link, cookie); 3241806b681cSAl Viro } 324210fa8e62SAl Viro out: 3243893b7775SAl Viro path_cleanup(nd); 3244f15133dfSAl Viro out2: 32452675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 32462675a4ebSAl Viro BUG_ON(!error); 324730d90494SAl Viro put_filp(file); 3248015c3bbcSMiklos Szeredi } 32492675a4ebSAl Viro if (unlikely(error)) { 32502675a4ebSAl Viro if (error == -EOPENSTALE) { 32512675a4ebSAl Viro if (flags & LOOKUP_RCU) 32522675a4ebSAl Viro error = -ECHILD; 32532675a4ebSAl Viro else 32542675a4ebSAl Viro error = -ESTALE; 32552675a4ebSAl Viro } 32562675a4ebSAl Viro file = ERR_PTR(error); 32572675a4ebSAl Viro } 32582675a4ebSAl Viro return file; 3259de459215SKirill Korotaev } 32601da177e4SLinus Torvalds 3261669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3262f9652e10SAl Viro const struct open_flags *op) 326313aab428SAl Viro { 326473d049a4SAl Viro struct nameidata nd; 3265f9652e10SAl Viro int flags = op->lookup_flags; 326613aab428SAl Viro struct file *filp; 326713aab428SAl Viro 326873d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 326913aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 327073d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 327113aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 327273d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 327313aab428SAl Viro return filp; 327413aab428SAl Viro } 327513aab428SAl Viro 327673d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3277f9652e10SAl Viro const char *name, const struct open_flags *op) 327873d049a4SAl Viro { 327973d049a4SAl Viro struct nameidata nd; 328073d049a4SAl Viro struct file *file; 328151689104SPaul Moore struct filename *filename; 3282f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 328373d049a4SAl Viro 328473d049a4SAl Viro nd.root.mnt = mnt; 328573d049a4SAl Viro nd.root.dentry = dentry; 328673d049a4SAl Viro 3287b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 328873d049a4SAl Viro return ERR_PTR(-ELOOP); 328973d049a4SAl Viro 329051689104SPaul Moore filename = getname_kernel(name); 329151689104SPaul Moore if (unlikely(IS_ERR(filename))) 329251689104SPaul Moore return ERR_CAST(filename); 329351689104SPaul Moore 329451689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_RCU); 329573d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 329651689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags); 329773d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 329851689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_REVAL); 329951689104SPaul Moore putname(filename); 330073d049a4SAl Viro return file; 330173d049a4SAl Viro } 330273d049a4SAl Viro 3303fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 33041ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 33051da177e4SLinus Torvalds { 3306c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3307ed75e95dSAl Viro struct nameidata nd; 3308c30dabfeSJan Kara int err2; 33091ac12b4bSJeff Layton int error; 33101ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 33111ac12b4bSJeff Layton 33121ac12b4bSJeff Layton /* 33131ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 33141ac12b4bSJeff Layton * other flags passed in are ignored! 33151ac12b4bSJeff Layton */ 33161ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 33171ac12b4bSJeff Layton 3318fa14a0b8SAl Viro error = filename_lookup(dfd, name, LOOKUP_PARENT|lookup_flags, &nd); 3319ed75e95dSAl Viro if (error) 3320ed75e95dSAl Viro return ERR_PTR(error); 33211da177e4SLinus Torvalds 3322c663e5d8SChristoph Hellwig /* 3323c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3324c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3325c663e5d8SChristoph Hellwig */ 3326ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 3327ed75e95dSAl Viro goto out; 3328ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 3329ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 3330c663e5d8SChristoph Hellwig 3331c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3332c30dabfeSJan Kara err2 = mnt_want_write(nd.path.mnt); 3333c663e5d8SChristoph Hellwig /* 3334c663e5d8SChristoph Hellwig * Do the final lookup. 3335c663e5d8SChristoph Hellwig */ 3336ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 33376a9f40d6SAl Viro dentry = __lookup_hash(&nd.last, nd.path.dentry, nd.flags); 33381da177e4SLinus Torvalds if (IS_ERR(dentry)) 3339a8104a9fSAl Viro goto unlock; 3340c663e5d8SChristoph Hellwig 3341a8104a9fSAl Viro error = -EEXIST; 3342b18825a7SDavid Howells if (d_is_positive(dentry)) 3343a8104a9fSAl Viro goto fail; 3344b18825a7SDavid Howells 3345c663e5d8SChristoph Hellwig /* 3346c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3347c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3348c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3349c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3350c663e5d8SChristoph Hellwig */ 3351ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 3352a8104a9fSAl Viro error = -ENOENT; 3353ed75e95dSAl Viro goto fail; 3354e9baf6e5SAl Viro } 3355c30dabfeSJan Kara if (unlikely(err2)) { 3356c30dabfeSJan Kara error = err2; 3357a8104a9fSAl Viro goto fail; 3358c30dabfeSJan Kara } 3359ed75e95dSAl Viro *path = nd.path; 3360e9baf6e5SAl Viro return dentry; 33611da177e4SLinus Torvalds fail: 3362a8104a9fSAl Viro dput(dentry); 3363a8104a9fSAl Viro dentry = ERR_PTR(error); 3364a8104a9fSAl Viro unlock: 3365dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3366c30dabfeSJan Kara if (!err2) 3367c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 3368ed75e95dSAl Viro out: 3369dae6ad8fSAl Viro path_put(&nd.path); 3370ed75e95dSAl Viro return dentry; 3371dae6ad8fSAl Viro } 3372fa14a0b8SAl Viro 3373fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3374fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3375fa14a0b8SAl Viro { 337651689104SPaul Moore struct filename *filename = getname_kernel(pathname); 337751689104SPaul Moore struct dentry *res; 337851689104SPaul Moore 337951689104SPaul Moore if (IS_ERR(filename)) 338051689104SPaul Moore return ERR_CAST(filename); 338151689104SPaul Moore res = filename_create(dfd, filename, path, lookup_flags); 338251689104SPaul Moore putname(filename); 338351689104SPaul Moore return res; 3384fa14a0b8SAl Viro } 3385dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3386dae6ad8fSAl Viro 3387921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3388921a1650SAl Viro { 3389921a1650SAl Viro dput(dentry); 3390921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3391a8104a9fSAl Viro mnt_drop_write(path->mnt); 3392921a1650SAl Viro path_put(path); 3393921a1650SAl Viro } 3394921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3395921a1650SAl Viro 33961ac12b4bSJeff Layton struct dentry *user_path_create(int dfd, const char __user *pathname, 33971ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3398dae6ad8fSAl Viro { 339991a27b2aSJeff Layton struct filename *tmp = getname(pathname); 3400dae6ad8fSAl Viro struct dentry *res; 3401dae6ad8fSAl Viro if (IS_ERR(tmp)) 3402dae6ad8fSAl Viro return ERR_CAST(tmp); 3403fa14a0b8SAl Viro res = filename_create(dfd, tmp, path, lookup_flags); 3404dae6ad8fSAl Viro putname(tmp); 3405dae6ad8fSAl Viro return res; 3406dae6ad8fSAl Viro } 3407dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3408dae6ad8fSAl Viro 34091a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 34101da177e4SLinus Torvalds { 3411a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 34121da177e4SLinus Torvalds 34131da177e4SLinus Torvalds if (error) 34141da177e4SLinus Torvalds return error; 34151da177e4SLinus Torvalds 3416975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 34171da177e4SLinus Torvalds return -EPERM; 34181da177e4SLinus Torvalds 3419acfa4380SAl Viro if (!dir->i_op->mknod) 34201da177e4SLinus Torvalds return -EPERM; 34211da177e4SLinus Torvalds 342208ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 342308ce5f16SSerge E. Hallyn if (error) 342408ce5f16SSerge E. Hallyn return error; 342508ce5f16SSerge E. Hallyn 34261da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 34271da177e4SLinus Torvalds if (error) 34281da177e4SLinus Torvalds return error; 34291da177e4SLinus Torvalds 34301da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3431a74574aaSStephen Smalley if (!error) 3432f38aa942SAmy Griffis fsnotify_create(dir, dentry); 34331da177e4SLinus Torvalds return error; 34341da177e4SLinus Torvalds } 34354d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 34361da177e4SLinus Torvalds 3437f69aac00SAl Viro static int may_mknod(umode_t mode) 3438463c3197SDave Hansen { 3439463c3197SDave Hansen switch (mode & S_IFMT) { 3440463c3197SDave Hansen case S_IFREG: 3441463c3197SDave Hansen case S_IFCHR: 3442463c3197SDave Hansen case S_IFBLK: 3443463c3197SDave Hansen case S_IFIFO: 3444463c3197SDave Hansen case S_IFSOCK: 3445463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3446463c3197SDave Hansen return 0; 3447463c3197SDave Hansen case S_IFDIR: 3448463c3197SDave Hansen return -EPERM; 3449463c3197SDave Hansen default: 3450463c3197SDave Hansen return -EINVAL; 3451463c3197SDave Hansen } 3452463c3197SDave Hansen } 3453463c3197SDave Hansen 34548208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 34552e4d0924SHeiko Carstens unsigned, dev) 34561da177e4SLinus Torvalds { 34571da177e4SLinus Torvalds struct dentry *dentry; 3458dae6ad8fSAl Viro struct path path; 3459dae6ad8fSAl Viro int error; 3460972567f1SJeff Layton unsigned int lookup_flags = 0; 34611da177e4SLinus Torvalds 34628e4bfca1SAl Viro error = may_mknod(mode); 34638e4bfca1SAl Viro if (error) 34648e4bfca1SAl Viro return error; 3465972567f1SJeff Layton retry: 3466972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3467dae6ad8fSAl Viro if (IS_ERR(dentry)) 3468dae6ad8fSAl Viro return PTR_ERR(dentry); 34692ad94ae6SAl Viro 3470dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3471ce3b0f8dSAl Viro mode &= ~current_umask(); 3472dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3473be6d3e56SKentaro Takeda if (error) 3474a8104a9fSAl Viro goto out; 34751da177e4SLinus Torvalds switch (mode & S_IFMT) { 34761da177e4SLinus Torvalds case 0: case S_IFREG: 3477312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 34781da177e4SLinus Torvalds break; 34791da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3480dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 34811da177e4SLinus Torvalds new_decode_dev(dev)); 34821da177e4SLinus Torvalds break; 34831da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3484dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 34851da177e4SLinus Torvalds break; 34861da177e4SLinus Torvalds } 3487a8104a9fSAl Viro out: 3488921a1650SAl Viro done_path_create(&path, dentry); 3489972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3490972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3491972567f1SJeff Layton goto retry; 3492972567f1SJeff Layton } 34931da177e4SLinus Torvalds return error; 34941da177e4SLinus Torvalds } 34951da177e4SLinus Torvalds 34968208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 34975590ff0dSUlrich Drepper { 34985590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 34995590ff0dSUlrich Drepper } 35005590ff0dSUlrich Drepper 350118bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 35021da177e4SLinus Torvalds { 3503a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35048de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 35051da177e4SLinus Torvalds 35061da177e4SLinus Torvalds if (error) 35071da177e4SLinus Torvalds return error; 35081da177e4SLinus Torvalds 3509acfa4380SAl Viro if (!dir->i_op->mkdir) 35101da177e4SLinus Torvalds return -EPERM; 35111da177e4SLinus Torvalds 35121da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 35131da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 35141da177e4SLinus Torvalds if (error) 35151da177e4SLinus Torvalds return error; 35161da177e4SLinus Torvalds 35178de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 35188de52778SAl Viro return -EMLINK; 35198de52778SAl Viro 35201da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3521a74574aaSStephen Smalley if (!error) 3522f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 35231da177e4SLinus Torvalds return error; 35241da177e4SLinus Torvalds } 35254d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 35261da177e4SLinus Torvalds 3527a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 35281da177e4SLinus Torvalds { 35296902d925SDave Hansen struct dentry *dentry; 3530dae6ad8fSAl Viro struct path path; 3531dae6ad8fSAl Viro int error; 3532b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 35331da177e4SLinus Torvalds 3534b76d8b82SJeff Layton retry: 3535b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 35366902d925SDave Hansen if (IS_ERR(dentry)) 3537dae6ad8fSAl Viro return PTR_ERR(dentry); 35386902d925SDave Hansen 3539dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3540ce3b0f8dSAl Viro mode &= ~current_umask(); 3541dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3542a8104a9fSAl Viro if (!error) 3543dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3544921a1650SAl Viro done_path_create(&path, dentry); 3545b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3546b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3547b76d8b82SJeff Layton goto retry; 3548b76d8b82SJeff Layton } 35491da177e4SLinus Torvalds return error; 35501da177e4SLinus Torvalds } 35511da177e4SLinus Torvalds 3552a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 35535590ff0dSUlrich Drepper { 35545590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 35555590ff0dSUlrich Drepper } 35565590ff0dSUlrich Drepper 35571da177e4SLinus Torvalds /* 3558a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3559c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3560a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3561a71905f0SSage Weil * then we drop the dentry now. 35621da177e4SLinus Torvalds * 35631da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 35641da177e4SLinus Torvalds * do a 35651da177e4SLinus Torvalds * 35661da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 35671da177e4SLinus Torvalds * return -EBUSY; 35681da177e4SLinus Torvalds * 35691da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 35701da177e4SLinus Torvalds * that is still in use by something else.. 35711da177e4SLinus Torvalds */ 35721da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 35731da177e4SLinus Torvalds { 35741da177e4SLinus Torvalds shrink_dcache_parent(dentry); 35751da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 357698474236SWaiman Long if (dentry->d_lockref.count == 1) 35771da177e4SLinus Torvalds __d_drop(dentry); 35781da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 35791da177e4SLinus Torvalds } 35804d359507SAl Viro EXPORT_SYMBOL(dentry_unhash); 35811da177e4SLinus Torvalds 35821da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 35831da177e4SLinus Torvalds { 35841da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 35851da177e4SLinus Torvalds 35861da177e4SLinus Torvalds if (error) 35871da177e4SLinus Torvalds return error; 35881da177e4SLinus Torvalds 3589acfa4380SAl Viro if (!dir->i_op->rmdir) 35901da177e4SLinus Torvalds return -EPERM; 35911da177e4SLinus Torvalds 35921d2ef590SAl Viro dget(dentry); 35931b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3594912dbc15SSage Weil 35951da177e4SLinus Torvalds error = -EBUSY; 35967af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3597912dbc15SSage Weil goto out; 3598912dbc15SSage Weil 35991da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3600912dbc15SSage Weil if (error) 3601912dbc15SSage Weil goto out; 3602912dbc15SSage Weil 36033cebde24SSage Weil shrink_dcache_parent(dentry); 36041da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3605912dbc15SSage Weil if (error) 3606912dbc15SSage Weil goto out; 3607912dbc15SSage Weil 36081da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3609d83c49f3SAl Viro dont_mount(dentry); 36108ed936b5SEric W. Biederman detach_mounts(dentry); 36111da177e4SLinus Torvalds 3612912dbc15SSage Weil out: 3613912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 36141d2ef590SAl Viro dput(dentry); 3615912dbc15SSage Weil if (!error) 3616912dbc15SSage Weil d_delete(dentry); 36171da177e4SLinus Torvalds return error; 36181da177e4SLinus Torvalds } 36194d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 36201da177e4SLinus Torvalds 36215590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 36221da177e4SLinus Torvalds { 36231da177e4SLinus Torvalds int error = 0; 362491a27b2aSJeff Layton struct filename *name; 36251da177e4SLinus Torvalds struct dentry *dentry; 3626f5beed75SAl Viro struct path path; 3627f5beed75SAl Viro struct qstr last; 3628f5beed75SAl Viro int type; 3629c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3630c6ee9206SJeff Layton retry: 3631f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3632f5beed75SAl Viro &path, &last, &type, lookup_flags); 363391a27b2aSJeff Layton if (IS_ERR(name)) 363491a27b2aSJeff Layton return PTR_ERR(name); 36351da177e4SLinus Torvalds 3636f5beed75SAl Viro switch (type) { 36371da177e4SLinus Torvalds case LAST_DOTDOT: 36381da177e4SLinus Torvalds error = -ENOTEMPTY; 36391da177e4SLinus Torvalds goto exit1; 36401da177e4SLinus Torvalds case LAST_DOT: 36411da177e4SLinus Torvalds error = -EINVAL; 36421da177e4SLinus Torvalds goto exit1; 36431da177e4SLinus Torvalds case LAST_ROOT: 36441da177e4SLinus Torvalds error = -EBUSY; 36451da177e4SLinus Torvalds goto exit1; 36461da177e4SLinus Torvalds } 36470612d9fbSOGAWA Hirofumi 3648f5beed75SAl Viro error = mnt_want_write(path.mnt); 3649c30dabfeSJan Kara if (error) 3650c30dabfeSJan Kara goto exit1; 36510612d9fbSOGAWA Hirofumi 3652f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3653f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 36541da177e4SLinus Torvalds error = PTR_ERR(dentry); 36556902d925SDave Hansen if (IS_ERR(dentry)) 36566902d925SDave Hansen goto exit2; 3657e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3658e6bc45d6STheodore Ts'o error = -ENOENT; 3659e6bc45d6STheodore Ts'o goto exit3; 3660e6bc45d6STheodore Ts'o } 3661f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3662be6d3e56SKentaro Takeda if (error) 3663c30dabfeSJan Kara goto exit3; 3664f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 36650622753bSDave Hansen exit3: 36661da177e4SLinus Torvalds dput(dentry); 36676902d925SDave Hansen exit2: 3668f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 3669f5beed75SAl Viro mnt_drop_write(path.mnt); 36701da177e4SLinus Torvalds exit1: 3671f5beed75SAl Viro path_put(&path); 36721da177e4SLinus Torvalds putname(name); 3673c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3674c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3675c6ee9206SJeff Layton goto retry; 3676c6ee9206SJeff Layton } 36771da177e4SLinus Torvalds return error; 36781da177e4SLinus Torvalds } 36791da177e4SLinus Torvalds 36803cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 36815590ff0dSUlrich Drepper { 36825590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 36835590ff0dSUlrich Drepper } 36845590ff0dSUlrich Drepper 3685b21996e3SJ. Bruce Fields /** 3686b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3687b21996e3SJ. Bruce Fields * @dir: parent directory 3688b21996e3SJ. Bruce Fields * @dentry: victim 3689b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3690b21996e3SJ. Bruce Fields * 3691b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3692b21996e3SJ. Bruce Fields * 3693b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3694b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3695b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3696b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3697b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3698b21996e3SJ. Bruce Fields * 3699b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3700b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3701b21996e3SJ. Bruce Fields * to be NFS exported. 3702b21996e3SJ. Bruce Fields */ 3703b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 37041da177e4SLinus Torvalds { 37059accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 37061da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 37071da177e4SLinus Torvalds 37081da177e4SLinus Torvalds if (error) 37091da177e4SLinus Torvalds return error; 37101da177e4SLinus Torvalds 3711acfa4380SAl Viro if (!dir->i_op->unlink) 37121da177e4SLinus Torvalds return -EPERM; 37131da177e4SLinus Torvalds 37149accbb97SJ. Bruce Fields mutex_lock(&target->i_mutex); 37158ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 37161da177e4SLinus Torvalds error = -EBUSY; 37171da177e4SLinus Torvalds else { 37181da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3719bec1052eSAl Viro if (!error) { 37205a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 37215a14696cSJ. Bruce Fields if (error) 3722b21996e3SJ. Bruce Fields goto out; 37231da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 37248ed936b5SEric W. Biederman if (!error) { 3725d83c49f3SAl Viro dont_mount(dentry); 37268ed936b5SEric W. Biederman detach_mounts(dentry); 37278ed936b5SEric W. Biederman } 3728bec1052eSAl Viro } 37291da177e4SLinus Torvalds } 3730b21996e3SJ. Bruce Fields out: 37319accbb97SJ. Bruce Fields mutex_unlock(&target->i_mutex); 37321da177e4SLinus Torvalds 37331da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 37341da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 37359accbb97SJ. Bruce Fields fsnotify_link_count(target); 37361da177e4SLinus Torvalds d_delete(dentry); 37371da177e4SLinus Torvalds } 37380eeca283SRobert Love 37391da177e4SLinus Torvalds return error; 37401da177e4SLinus Torvalds } 37414d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 37421da177e4SLinus Torvalds 37431da177e4SLinus Torvalds /* 37441da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 37451b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 37461da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 37471da177e4SLinus Torvalds * while waiting on the I/O. 37481da177e4SLinus Torvalds */ 37495590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 37501da177e4SLinus Torvalds { 37512ad94ae6SAl Viro int error; 375291a27b2aSJeff Layton struct filename *name; 37531da177e4SLinus Torvalds struct dentry *dentry; 3754f5beed75SAl Viro struct path path; 3755f5beed75SAl Viro struct qstr last; 3756f5beed75SAl Viro int type; 37571da177e4SLinus Torvalds struct inode *inode = NULL; 3758b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 37595d18f813SJeff Layton unsigned int lookup_flags = 0; 37605d18f813SJeff Layton retry: 3761f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3762f5beed75SAl Viro &path, &last, &type, lookup_flags); 376391a27b2aSJeff Layton if (IS_ERR(name)) 376491a27b2aSJeff Layton return PTR_ERR(name); 37652ad94ae6SAl Viro 37661da177e4SLinus Torvalds error = -EISDIR; 3767f5beed75SAl Viro if (type != LAST_NORM) 37681da177e4SLinus Torvalds goto exit1; 37690612d9fbSOGAWA Hirofumi 3770f5beed75SAl Viro error = mnt_want_write(path.mnt); 3771c30dabfeSJan Kara if (error) 3772c30dabfeSJan Kara goto exit1; 3773b21996e3SJ. Bruce Fields retry_deleg: 3774f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3775f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 37761da177e4SLinus Torvalds error = PTR_ERR(dentry); 37771da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 37781da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3779f5beed75SAl Viro if (last.name[last.len]) 378050338b88STörök Edwin goto slashes; 37811da177e4SLinus Torvalds inode = dentry->d_inode; 3782b18825a7SDavid Howells if (d_is_negative(dentry)) 3783e6bc45d6STheodore Ts'o goto slashes; 37847de9c6eeSAl Viro ihold(inode); 3785f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3786be6d3e56SKentaro Takeda if (error) 3787c30dabfeSJan Kara goto exit2; 3788f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 37891da177e4SLinus Torvalds exit2: 37901da177e4SLinus Torvalds dput(dentry); 37911da177e4SLinus Torvalds } 3792f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 37931da177e4SLinus Torvalds if (inode) 37941da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3795b21996e3SJ. Bruce Fields inode = NULL; 3796b21996e3SJ. Bruce Fields if (delegated_inode) { 37975a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3798b21996e3SJ. Bruce Fields if (!error) 3799b21996e3SJ. Bruce Fields goto retry_deleg; 3800b21996e3SJ. Bruce Fields } 3801f5beed75SAl Viro mnt_drop_write(path.mnt); 38021da177e4SLinus Torvalds exit1: 3803f5beed75SAl Viro path_put(&path); 38041da177e4SLinus Torvalds putname(name); 38055d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 38065d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 38075d18f813SJeff Layton inode = NULL; 38085d18f813SJeff Layton goto retry; 38095d18f813SJeff Layton } 38101da177e4SLinus Torvalds return error; 38111da177e4SLinus Torvalds 38121da177e4SLinus Torvalds slashes: 3813b18825a7SDavid Howells if (d_is_negative(dentry)) 3814b18825a7SDavid Howells error = -ENOENT; 381544b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3816b18825a7SDavid Howells error = -EISDIR; 3817b18825a7SDavid Howells else 3818b18825a7SDavid Howells error = -ENOTDIR; 38191da177e4SLinus Torvalds goto exit2; 38201da177e4SLinus Torvalds } 38211da177e4SLinus Torvalds 38222e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 38235590ff0dSUlrich Drepper { 38245590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 38255590ff0dSUlrich Drepper return -EINVAL; 38265590ff0dSUlrich Drepper 38275590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 38285590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 38295590ff0dSUlrich Drepper 38305590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 38315590ff0dSUlrich Drepper } 38325590ff0dSUlrich Drepper 38333480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 38345590ff0dSUlrich Drepper { 38355590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 38365590ff0dSUlrich Drepper } 38375590ff0dSUlrich Drepper 3838db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 38391da177e4SLinus Torvalds { 3840a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 38411da177e4SLinus Torvalds 38421da177e4SLinus Torvalds if (error) 38431da177e4SLinus Torvalds return error; 38441da177e4SLinus Torvalds 3845acfa4380SAl Viro if (!dir->i_op->symlink) 38461da177e4SLinus Torvalds return -EPERM; 38471da177e4SLinus Torvalds 38481da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 38491da177e4SLinus Torvalds if (error) 38501da177e4SLinus Torvalds return error; 38511da177e4SLinus Torvalds 38521da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3853a74574aaSStephen Smalley if (!error) 3854f38aa942SAmy Griffis fsnotify_create(dir, dentry); 38551da177e4SLinus Torvalds return error; 38561da177e4SLinus Torvalds } 38574d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 38581da177e4SLinus Torvalds 38592e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 38602e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 38611da177e4SLinus Torvalds { 38622ad94ae6SAl Viro int error; 386391a27b2aSJeff Layton struct filename *from; 38646902d925SDave Hansen struct dentry *dentry; 3865dae6ad8fSAl Viro struct path path; 3866f46d3567SJeff Layton unsigned int lookup_flags = 0; 38671da177e4SLinus Torvalds 38681da177e4SLinus Torvalds from = getname(oldname); 38691da177e4SLinus Torvalds if (IS_ERR(from)) 38701da177e4SLinus Torvalds return PTR_ERR(from); 3871f46d3567SJeff Layton retry: 3872f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 38731da177e4SLinus Torvalds error = PTR_ERR(dentry); 38746902d925SDave Hansen if (IS_ERR(dentry)) 3875dae6ad8fSAl Viro goto out_putname; 38766902d925SDave Hansen 387791a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3878a8104a9fSAl Viro if (!error) 387991a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3880921a1650SAl Viro done_path_create(&path, dentry); 3881f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 3882f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 3883f46d3567SJeff Layton goto retry; 3884f46d3567SJeff Layton } 38856902d925SDave Hansen out_putname: 38861da177e4SLinus Torvalds putname(from); 38871da177e4SLinus Torvalds return error; 38881da177e4SLinus Torvalds } 38891da177e4SLinus Torvalds 38903480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 38915590ff0dSUlrich Drepper { 38925590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 38935590ff0dSUlrich Drepper } 38945590ff0dSUlrich Drepper 3895146a8595SJ. Bruce Fields /** 3896146a8595SJ. Bruce Fields * vfs_link - create a new link 3897146a8595SJ. Bruce Fields * @old_dentry: object to be linked 3898146a8595SJ. Bruce Fields * @dir: new parent 3899146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 3900146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 3901146a8595SJ. Bruce Fields * 3902146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 3903146a8595SJ. Bruce Fields * 3904146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 3905146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 3906146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 3907146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 3908146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 3909146a8595SJ. Bruce Fields * 3910146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3911146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3912146a8595SJ. Bruce Fields * to be NFS exported. 3913146a8595SJ. Bruce Fields */ 3914146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 39151da177e4SLinus Torvalds { 39161da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 39178de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 39181da177e4SLinus Torvalds int error; 39191da177e4SLinus Torvalds 39201da177e4SLinus Torvalds if (!inode) 39211da177e4SLinus Torvalds return -ENOENT; 39221da177e4SLinus Torvalds 3923a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 39241da177e4SLinus Torvalds if (error) 39251da177e4SLinus Torvalds return error; 39261da177e4SLinus Torvalds 39271da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 39281da177e4SLinus Torvalds return -EXDEV; 39291da177e4SLinus Torvalds 39301da177e4SLinus Torvalds /* 39311da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 39321da177e4SLinus Torvalds */ 39331da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 39341da177e4SLinus Torvalds return -EPERM; 3935acfa4380SAl Viro if (!dir->i_op->link) 39361da177e4SLinus Torvalds return -EPERM; 39377e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 39381da177e4SLinus Torvalds return -EPERM; 39391da177e4SLinus Torvalds 39401da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 39411da177e4SLinus Torvalds if (error) 39421da177e4SLinus Torvalds return error; 39431da177e4SLinus Torvalds 39447e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 3945aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 3946f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 3947aae8a97dSAneesh Kumar K.V error = -ENOENT; 39488de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 39498de52778SAl Viro error = -EMLINK; 3950146a8595SJ. Bruce Fields else { 3951146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 3952146a8595SJ. Bruce Fields if (!error) 39531da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 3954146a8595SJ. Bruce Fields } 3955f4e0c30cSAl Viro 3956f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 3957f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3958f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 3959f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3960f4e0c30cSAl Viro } 39617e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 3962e31e14ecSStephen Smalley if (!error) 39637e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 39641da177e4SLinus Torvalds return error; 39651da177e4SLinus Torvalds } 39664d359507SAl Viro EXPORT_SYMBOL(vfs_link); 39671da177e4SLinus Torvalds 39681da177e4SLinus Torvalds /* 39691da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 39701da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 39711da177e4SLinus Torvalds * newname. --KAB 39721da177e4SLinus Torvalds * 39731da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 39741da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 39751da177e4SLinus Torvalds * and other special files. --ADM 39761da177e4SLinus Torvalds */ 39772e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 39782e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 39791da177e4SLinus Torvalds { 39801da177e4SLinus Torvalds struct dentry *new_dentry; 3981dae6ad8fSAl Viro struct path old_path, new_path; 3982146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 398311a7b371SAneesh Kumar K.V int how = 0; 39841da177e4SLinus Torvalds int error; 39851da177e4SLinus Torvalds 398611a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 3987c04030e1SUlrich Drepper return -EINVAL; 398811a7b371SAneesh Kumar K.V /* 3989f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 3990f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 3991f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 399211a7b371SAneesh Kumar K.V */ 3993f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 3994f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 3995f0cc6ffbSLinus Torvalds return -ENOENT; 399611a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 3997f0cc6ffbSLinus Torvalds } 3998c04030e1SUlrich Drepper 399911a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 400011a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4001442e31caSJeff Layton retry: 400211a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 40031da177e4SLinus Torvalds if (error) 40042ad94ae6SAl Viro return error; 40052ad94ae6SAl Viro 4006442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4007442e31caSJeff Layton (how & LOOKUP_REVAL)); 40081da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 40096902d925SDave Hansen if (IS_ERR(new_dentry)) 4010dae6ad8fSAl Viro goto out; 4011dae6ad8fSAl Viro 4012dae6ad8fSAl Viro error = -EXDEV; 4013dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4014dae6ad8fSAl Viro goto out_dput; 4015800179c9SKees Cook error = may_linkat(&old_path); 4016800179c9SKees Cook if (unlikely(error)) 4017800179c9SKees Cook goto out_dput; 4018dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4019be6d3e56SKentaro Takeda if (error) 4020a8104a9fSAl Viro goto out_dput; 4021146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 402275c3f29dSDave Hansen out_dput: 4023921a1650SAl Viro done_path_create(&new_path, new_dentry); 4024146a8595SJ. Bruce Fields if (delegated_inode) { 4025146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4026d22e6338SOleg Drokin if (!error) { 4027d22e6338SOleg Drokin path_put(&old_path); 4028146a8595SJ. Bruce Fields goto retry; 4029146a8595SJ. Bruce Fields } 4030d22e6338SOleg Drokin } 4031442e31caSJeff Layton if (retry_estale(error, how)) { 4032d22e6338SOleg Drokin path_put(&old_path); 4033442e31caSJeff Layton how |= LOOKUP_REVAL; 4034442e31caSJeff Layton goto retry; 4035442e31caSJeff Layton } 40361da177e4SLinus Torvalds out: 40372d8f3038SAl Viro path_put(&old_path); 40381da177e4SLinus Torvalds 40391da177e4SLinus Torvalds return error; 40401da177e4SLinus Torvalds } 40411da177e4SLinus Torvalds 40423480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 40435590ff0dSUlrich Drepper { 4044c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 40455590ff0dSUlrich Drepper } 40465590ff0dSUlrich Drepper 4047bc27027aSMiklos Szeredi /** 4048bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4049bc27027aSMiklos Szeredi * @old_dir: parent of source 4050bc27027aSMiklos Szeredi * @old_dentry: source 4051bc27027aSMiklos Szeredi * @new_dir: parent of destination 4052bc27027aSMiklos Szeredi * @new_dentry: destination 4053bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4054520c8b16SMiklos Szeredi * @flags: rename flags 4055bc27027aSMiklos Szeredi * 4056bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4057bc27027aSMiklos Szeredi * 4058bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4059bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4060bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4061bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4062bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4063bc27027aSMiklos Szeredi * so. 4064bc27027aSMiklos Szeredi * 4065bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4066bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4067bc27027aSMiklos Szeredi * to be NFS exported. 4068bc27027aSMiklos Szeredi * 40691da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 40701da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 40711da177e4SLinus Torvalds * Problems: 4072d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 40731da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 40741da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4075a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 40761da177e4SLinus Torvalds * story. 40776cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 40786cedba89SJ. Bruce Fields * and source (if it is not a directory). 40791b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 40801da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 40811da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4082a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 40831da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 40841da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 40851da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4086a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 40871da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 40881da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 40891da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4090e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 40911b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 40921da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4093c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 40941da177e4SLinus Torvalds * locking]. 40951da177e4SLinus Torvalds */ 40961da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 40978e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4098520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 40991da177e4SLinus Torvalds { 41001da177e4SLinus Torvalds int error; 4101bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 410259b0df21SEric Paris const unsigned char *old_name; 4103bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4104bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4105da1ce067SMiklos Szeredi bool new_is_dir = false; 4106da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 41071da177e4SLinus Torvalds 4108bc27027aSMiklos Szeredi if (source == target) 41091da177e4SLinus Torvalds return 0; 41101da177e4SLinus Torvalds 41111da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 41121da177e4SLinus Torvalds if (error) 41131da177e4SLinus Torvalds return error; 41141da177e4SLinus Torvalds 4115da1ce067SMiklos Szeredi if (!target) { 4116a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4117da1ce067SMiklos Szeredi } else { 4118da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4119da1ce067SMiklos Szeredi 4120da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 41211da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4122da1ce067SMiklos Szeredi else 4123da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4124da1ce067SMiklos Szeredi } 41251da177e4SLinus Torvalds if (error) 41261da177e4SLinus Torvalds return error; 41271da177e4SLinus Torvalds 41287177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 41291da177e4SLinus Torvalds return -EPERM; 41301da177e4SLinus Torvalds 4131520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4132520c8b16SMiklos Szeredi return -EINVAL; 4133520c8b16SMiklos Szeredi 4134bc27027aSMiklos Szeredi /* 4135bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4136bc27027aSMiklos Szeredi * we'll need to flip '..'. 4137bc27027aSMiklos Szeredi */ 4138da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4139da1ce067SMiklos Szeredi if (is_dir) { 4140bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4141bc27027aSMiklos Szeredi if (error) 4142bc27027aSMiklos Szeredi return error; 4143bc27027aSMiklos Szeredi } 4144da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4145da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4146da1ce067SMiklos Szeredi if (error) 4147da1ce067SMiklos Szeredi return error; 4148da1ce067SMiklos Szeredi } 4149da1ce067SMiklos Szeredi } 41500eeca283SRobert Love 41510b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 41520b3974ebSMiklos Szeredi flags); 4153bc27027aSMiklos Szeredi if (error) 4154bc27027aSMiklos Szeredi return error; 4155bc27027aSMiklos Szeredi 4156bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4157bc27027aSMiklos Szeredi dget(new_dentry); 4158da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4159bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4160bc27027aSMiklos Szeredi else if (target) 4161bc27027aSMiklos Szeredi mutex_lock(&target->i_mutex); 4162bc27027aSMiklos Szeredi 4163bc27027aSMiklos Szeredi error = -EBUSY; 41647af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4165bc27027aSMiklos Szeredi goto out; 4166bc27027aSMiklos Szeredi 4167da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4168bc27027aSMiklos Szeredi error = -EMLINK; 4169da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4170bc27027aSMiklos Szeredi goto out; 4171da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4172da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4173da1ce067SMiklos Szeredi goto out; 4174da1ce067SMiklos Szeredi } 4175da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4176bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4177da1ce067SMiklos Szeredi if (!is_dir) { 4178bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4179bc27027aSMiklos Szeredi if (error) 4180bc27027aSMiklos Szeredi goto out; 4181da1ce067SMiklos Szeredi } 4182da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4183bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4184bc27027aSMiklos Szeredi if (error) 4185bc27027aSMiklos Szeredi goto out; 4186bc27027aSMiklos Szeredi } 41877177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4188520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4189520c8b16SMiklos Szeredi new_dir, new_dentry); 4190520c8b16SMiklos Szeredi } else { 41917177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4192520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4193520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4194520c8b16SMiklos Szeredi } 4195bc27027aSMiklos Szeredi if (error) 4196bc27027aSMiklos Szeredi goto out; 4197bc27027aSMiklos Szeredi 4198da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 41991da177e4SLinus Torvalds if (is_dir) 4200bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4201bc27027aSMiklos Szeredi dont_mount(new_dentry); 42028ed936b5SEric W. Biederman detach_mounts(new_dentry); 4203bc27027aSMiklos Szeredi } 4204da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4205da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4206bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4207da1ce067SMiklos Szeredi else 4208da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4209da1ce067SMiklos Szeredi } 4210bc27027aSMiklos Szeredi out: 4211da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4212bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4213bc27027aSMiklos Szeredi else if (target) 4214bc27027aSMiklos Szeredi mutex_unlock(&target->i_mutex); 4215bc27027aSMiklos Szeredi dput(new_dentry); 4216da1ce067SMiklos Szeredi if (!error) { 4217123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4218da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4219da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4220da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4221da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4222da1ce067SMiklos Szeredi } 4223da1ce067SMiklos Szeredi } 42240eeca283SRobert Love fsnotify_oldname_free(old_name); 42250eeca283SRobert Love 42261da177e4SLinus Torvalds return error; 42271da177e4SLinus Torvalds } 42284d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 42291da177e4SLinus Torvalds 4230520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4231520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 42321da177e4SLinus Torvalds { 42331da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 42341da177e4SLinus Torvalds struct dentry *trap; 4235f5beed75SAl Viro struct path old_path, new_path; 4236f5beed75SAl Viro struct qstr old_last, new_last; 4237f5beed75SAl Viro int old_type, new_type; 42388e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 423991a27b2aSJeff Layton struct filename *from; 424091a27b2aSJeff Layton struct filename *to; 4241f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4242c6a94284SJeff Layton bool should_retry = false; 42432ad94ae6SAl Viro int error; 4244520c8b16SMiklos Szeredi 42450d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4246da1ce067SMiklos Szeredi return -EINVAL; 4247da1ce067SMiklos Szeredi 42480d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 42490d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4250520c8b16SMiklos Szeredi return -EINVAL; 4251520c8b16SMiklos Szeredi 42520d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 42530d7a8555SMiklos Szeredi return -EPERM; 42540d7a8555SMiklos Szeredi 4255f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4256f5beed75SAl Viro target_flags = 0; 4257f5beed75SAl Viro 4258c6a94284SJeff Layton retry: 4259f5beed75SAl Viro from = user_path_parent(olddfd, oldname, 4260f5beed75SAl Viro &old_path, &old_last, &old_type, lookup_flags); 426191a27b2aSJeff Layton if (IS_ERR(from)) { 426291a27b2aSJeff Layton error = PTR_ERR(from); 42631da177e4SLinus Torvalds goto exit; 426491a27b2aSJeff Layton } 42651da177e4SLinus Torvalds 4266f5beed75SAl Viro to = user_path_parent(newdfd, newname, 4267f5beed75SAl Viro &new_path, &new_last, &new_type, lookup_flags); 426891a27b2aSJeff Layton if (IS_ERR(to)) { 426991a27b2aSJeff Layton error = PTR_ERR(to); 42701da177e4SLinus Torvalds goto exit1; 427191a27b2aSJeff Layton } 42721da177e4SLinus Torvalds 42731da177e4SLinus Torvalds error = -EXDEV; 4274f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 42751da177e4SLinus Torvalds goto exit2; 42761da177e4SLinus Torvalds 42771da177e4SLinus Torvalds error = -EBUSY; 4278f5beed75SAl Viro if (old_type != LAST_NORM) 42791da177e4SLinus Torvalds goto exit2; 42801da177e4SLinus Torvalds 42810a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 42820a7c3937SMiklos Szeredi error = -EEXIST; 4283f5beed75SAl Viro if (new_type != LAST_NORM) 42841da177e4SLinus Torvalds goto exit2; 42851da177e4SLinus Torvalds 4286f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4287c30dabfeSJan Kara if (error) 4288c30dabfeSJan Kara goto exit2; 4289c30dabfeSJan Kara 42908e6d782cSJ. Bruce Fields retry_deleg: 4291f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 42921da177e4SLinus Torvalds 4293f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 42941da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 42951da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 42961da177e4SLinus Torvalds goto exit3; 42971da177e4SLinus Torvalds /* source must exist */ 42981da177e4SLinus Torvalds error = -ENOENT; 4299b18825a7SDavid Howells if (d_is_negative(old_dentry)) 43001da177e4SLinus Torvalds goto exit4; 4301f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 43021da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 43031da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 43041da177e4SLinus Torvalds goto exit4; 43050a7c3937SMiklos Szeredi error = -EEXIST; 43060a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 43070a7c3937SMiklos Szeredi goto exit5; 4308da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4309da1ce067SMiklos Szeredi error = -ENOENT; 4310da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4311da1ce067SMiklos Szeredi goto exit5; 4312da1ce067SMiklos Szeredi 4313da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4314da1ce067SMiklos Szeredi error = -ENOTDIR; 4315f5beed75SAl Viro if (new_last.name[new_last.len]) 4316da1ce067SMiklos Szeredi goto exit5; 4317da1ce067SMiklos Szeredi } 4318da1ce067SMiklos Szeredi } 43190a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 43200a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 43210a7c3937SMiklos Szeredi error = -ENOTDIR; 4322f5beed75SAl Viro if (old_last.name[old_last.len]) 43230a7c3937SMiklos Szeredi goto exit5; 4324f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 43250a7c3937SMiklos Szeredi goto exit5; 43260a7c3937SMiklos Szeredi } 43270a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 43280a7c3937SMiklos Szeredi error = -EINVAL; 43290a7c3937SMiklos Szeredi if (old_dentry == trap) 43300a7c3937SMiklos Szeredi goto exit5; 43311da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4332da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43331da177e4SLinus Torvalds error = -ENOTEMPTY; 43341da177e4SLinus Torvalds if (new_dentry == trap) 43351da177e4SLinus Torvalds goto exit5; 43361da177e4SLinus Torvalds 4337f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4338f5beed75SAl Viro &new_path, new_dentry, flags); 4339be6d3e56SKentaro Takeda if (error) 4340c30dabfeSJan Kara goto exit5; 4341f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4342f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4343520c8b16SMiklos Szeredi &delegated_inode, flags); 43441da177e4SLinus Torvalds exit5: 43451da177e4SLinus Torvalds dput(new_dentry); 43461da177e4SLinus Torvalds exit4: 43471da177e4SLinus Torvalds dput(old_dentry); 43481da177e4SLinus Torvalds exit3: 4349f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 43508e6d782cSJ. Bruce Fields if (delegated_inode) { 43518e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 43528e6d782cSJ. Bruce Fields if (!error) 43538e6d782cSJ. Bruce Fields goto retry_deleg; 43548e6d782cSJ. Bruce Fields } 4355f5beed75SAl Viro mnt_drop_write(old_path.mnt); 43561da177e4SLinus Torvalds exit2: 4357c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4358c6a94284SJeff Layton should_retry = true; 4359f5beed75SAl Viro path_put(&new_path); 43602ad94ae6SAl Viro putname(to); 43611da177e4SLinus Torvalds exit1: 4362f5beed75SAl Viro path_put(&old_path); 43631da177e4SLinus Torvalds putname(from); 4364c6a94284SJeff Layton if (should_retry) { 4365c6a94284SJeff Layton should_retry = false; 4366c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4367c6a94284SJeff Layton goto retry; 4368c6a94284SJeff Layton } 43692ad94ae6SAl Viro exit: 43701da177e4SLinus Torvalds return error; 43711da177e4SLinus Torvalds } 43721da177e4SLinus Torvalds 4373520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4374520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4375520c8b16SMiklos Szeredi { 4376520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4377520c8b16SMiklos Szeredi } 4378520c8b16SMiklos Szeredi 4379a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 43805590ff0dSUlrich Drepper { 4381520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 43825590ff0dSUlrich Drepper } 43835590ff0dSUlrich Drepper 4384787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4385787fb6bcSMiklos Szeredi { 4386787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4387787fb6bcSMiklos Szeredi if (error) 4388787fb6bcSMiklos Szeredi return error; 4389787fb6bcSMiklos Szeredi 4390787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4391787fb6bcSMiklos Szeredi return -EPERM; 4392787fb6bcSMiklos Szeredi 4393787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4394787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4395787fb6bcSMiklos Szeredi } 4396787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4397787fb6bcSMiklos Szeredi 43985d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 43991da177e4SLinus Torvalds { 44005d826c84SAl Viro int len = PTR_ERR(link); 44011da177e4SLinus Torvalds if (IS_ERR(link)) 44021da177e4SLinus Torvalds goto out; 44031da177e4SLinus Torvalds 44041da177e4SLinus Torvalds len = strlen(link); 44051da177e4SLinus Torvalds if (len > (unsigned) buflen) 44061da177e4SLinus Torvalds len = buflen; 44071da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 44081da177e4SLinus Torvalds len = -EFAULT; 44091da177e4SLinus Torvalds out: 44101da177e4SLinus Torvalds return len; 44111da177e4SLinus Torvalds } 44125d826c84SAl Viro EXPORT_SYMBOL(readlink_copy); 44131da177e4SLinus Torvalds 44141da177e4SLinus Torvalds /* 44151da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 44161da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 44171da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 44181da177e4SLinus Torvalds */ 44191da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44201da177e4SLinus Torvalds { 4421cc314eefSLinus Torvalds void *cookie; 4422d4dee48bSAl Viro const char *link = dentry->d_inode->i_link; 4423694a1764SMarcin Slusarz int res; 4424cc314eefSLinus Torvalds 4425d4dee48bSAl Viro if (!link) { 4426d4dee48bSAl Viro link = dentry->d_inode->i_op->follow_link(dentry, &cookie, NULL); 4427680baacbSAl Viro if (IS_ERR(link)) 4428680baacbSAl Viro return PTR_ERR(link); 4429d4dee48bSAl Viro } 4430680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 4431680baacbSAl Viro if (cookie && dentry->d_inode->i_op->put_link) 4432680baacbSAl Viro dentry->d_inode->i_op->put_link(dentry, cookie); 4433694a1764SMarcin Slusarz return res; 44341da177e4SLinus Torvalds } 44354d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 44361da177e4SLinus Torvalds 44371da177e4SLinus Torvalds /* get the link contents into pagecache */ 44381da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 44391da177e4SLinus Torvalds { 4440ebd09abbSDuane Griffin char *kaddr; 44411da177e4SLinus Torvalds struct page *page; 44421da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 4443090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 44441da177e4SLinus Torvalds if (IS_ERR(page)) 44456fe6900eSNick Piggin return (char*)page; 44461da177e4SLinus Torvalds *ppage = page; 4447ebd09abbSDuane Griffin kaddr = kmap(page); 4448ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 4449ebd09abbSDuane Griffin return kaddr; 44501da177e4SLinus Torvalds } 44511da177e4SLinus Torvalds 44521da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44531da177e4SLinus Torvalds { 44541da177e4SLinus Torvalds struct page *page = NULL; 44555d826c84SAl Viro int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); 44561da177e4SLinus Torvalds if (page) { 44571da177e4SLinus Torvalds kunmap(page); 44581da177e4SLinus Torvalds page_cache_release(page); 44591da177e4SLinus Torvalds } 44601da177e4SLinus Torvalds return res; 44611da177e4SLinus Torvalds } 44624d359507SAl Viro EXPORT_SYMBOL(page_readlink); 44631da177e4SLinus Torvalds 4464680baacbSAl Viro const char *page_follow_link_light(struct dentry *dentry, void **cookie, struct nameidata *nd) 44651da177e4SLinus Torvalds { 4466cc314eefSLinus Torvalds struct page *page = NULL; 4467680baacbSAl Viro char *res = page_getlink(dentry, &page); 4468680baacbSAl Viro if (!IS_ERR(res)) 4469680baacbSAl Viro *cookie = page; 4470680baacbSAl Viro return res; 44711da177e4SLinus Torvalds } 44724d359507SAl Viro EXPORT_SYMBOL(page_follow_link_light); 44731da177e4SLinus Torvalds 4474680baacbSAl Viro void page_put_link(struct dentry *dentry, void *cookie) 44751da177e4SLinus Torvalds { 4476cc314eefSLinus Torvalds struct page *page = cookie; 44771da177e4SLinus Torvalds kunmap(page); 44781da177e4SLinus Torvalds page_cache_release(page); 44791da177e4SLinus Torvalds } 44804d359507SAl Viro EXPORT_SYMBOL(page_put_link); 44811da177e4SLinus Torvalds 448254566b2cSNick Piggin /* 448354566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 448454566b2cSNick Piggin */ 448554566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 44861da177e4SLinus Torvalds { 44871da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 44880adb25d2SKirill Korotaev struct page *page; 4489afddba49SNick Piggin void *fsdata; 4490beb497abSDmitriy Monakhov int err; 44911da177e4SLinus Torvalds char *kaddr; 449254566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 449354566b2cSNick Piggin if (nofs) 449454566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 44951da177e4SLinus Torvalds 44967e53cac4SNeilBrown retry: 4497afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 449854566b2cSNick Piggin flags, &page, &fsdata); 44991da177e4SLinus Torvalds if (err) 4500afddba49SNick Piggin goto fail; 4501afddba49SNick Piggin 4502e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 45031da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 4504e8e3c3d6SCong Wang kunmap_atomic(kaddr); 4505afddba49SNick Piggin 4506afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4507afddba49SNick Piggin page, fsdata); 45081da177e4SLinus Torvalds if (err < 0) 45091da177e4SLinus Torvalds goto fail; 4510afddba49SNick Piggin if (err < len-1) 4511afddba49SNick Piggin goto retry; 4512afddba49SNick Piggin 45131da177e4SLinus Torvalds mark_inode_dirty(inode); 45141da177e4SLinus Torvalds return 0; 45151da177e4SLinus Torvalds fail: 45161da177e4SLinus Torvalds return err; 45171da177e4SLinus Torvalds } 45184d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 45191da177e4SLinus Torvalds 45200adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 45210adb25d2SKirill Korotaev { 45220adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 452354566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 45240adb25d2SKirill Korotaev } 45254d359507SAl Viro EXPORT_SYMBOL(page_symlink); 45260adb25d2SKirill Korotaev 452792e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 45281da177e4SLinus Torvalds .readlink = generic_readlink, 45291da177e4SLinus Torvalds .follow_link = page_follow_link_light, 45301da177e4SLinus Torvalds .put_link = page_put_link, 45311da177e4SLinus Torvalds }; 45321da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 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