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... */ 268b8a7a3a6SAndreas Gruenbacher if (is_uncached_acl(acl)) 269e77819e5SLinus Torvalds return -ECHILD; 270206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 271e77819e5SLinus Torvalds } 272e77819e5SLinus Torvalds 2732982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2744e34e719SChristoph Hellwig if (IS_ERR(acl)) 2754e34e719SChristoph Hellwig return PTR_ERR(acl); 276e77819e5SLinus Torvalds if (acl) { 277e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 278e77819e5SLinus Torvalds posix_acl_release(acl); 279e77819e5SLinus Torvalds return error; 280e77819e5SLinus Torvalds } 28184635d68SLinus Torvalds #endif 282e77819e5SLinus Torvalds 283e77819e5SLinus Torvalds return -EAGAIN; 284e77819e5SLinus Torvalds } 285e77819e5SLinus Torvalds 2865909ccaaSLinus Torvalds /* 287948409c7SAndreas Gruenbacher * This does the basic permission checking 2885909ccaaSLinus Torvalds */ 2897e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2905909ccaaSLinus Torvalds { 29126cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2925909ccaaSLinus Torvalds 2938e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2945909ccaaSLinus Torvalds mode >>= 6; 2955909ccaaSLinus Torvalds else { 296e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2977e40145eSAl Viro int error = check_acl(inode, mask); 2985909ccaaSLinus Torvalds if (error != -EAGAIN) 2995909ccaaSLinus Torvalds return error; 3005909ccaaSLinus Torvalds } 3015909ccaaSLinus Torvalds 3025909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3035909ccaaSLinus Torvalds mode >>= 3; 3045909ccaaSLinus Torvalds } 3055909ccaaSLinus Torvalds 3065909ccaaSLinus Torvalds /* 3075909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3085909ccaaSLinus Torvalds */ 3099c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3105909ccaaSLinus Torvalds return 0; 3115909ccaaSLinus Torvalds return -EACCES; 3125909ccaaSLinus Torvalds } 3131da177e4SLinus Torvalds 3141da177e4SLinus Torvalds /** 3151da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3161da177e4SLinus Torvalds * @inode: inode to check access rights for 3178fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3181da177e4SLinus Torvalds * 3191da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3201da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3211da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 322b74c79e9SNick Piggin * are used for other things. 323b74c79e9SNick Piggin * 324b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 325b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 326b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3271da177e4SLinus Torvalds */ 3282830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3291da177e4SLinus Torvalds { 3305909ccaaSLinus Torvalds int ret; 3311da177e4SLinus Torvalds 3321da177e4SLinus Torvalds /* 333948409c7SAndreas Gruenbacher * Do the basic permission checks. 3341da177e4SLinus Torvalds */ 3357e40145eSAl Viro ret = acl_permission_check(inode, mask); 3365909ccaaSLinus Torvalds if (ret != -EACCES) 3375909ccaaSLinus Torvalds return ret; 3381da177e4SLinus Torvalds 339d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 340d594e7ecSAl Viro /* DACs are overridable for directories */ 34123adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 342d594e7ecSAl Viro return 0; 343d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34423adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34523adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 346d594e7ecSAl Viro return 0; 347d594e7ecSAl Viro return -EACCES; 348d594e7ecSAl Viro } 3491da177e4SLinus Torvalds /* 3501da177e4SLinus Torvalds * Read/write DACs are always overridable. 351d594e7ecSAl Viro * Executable DACs are overridable when there is 352d594e7ecSAl Viro * at least one exec bit set. 3531da177e4SLinus Torvalds */ 354d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 35523adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3561da177e4SLinus Torvalds return 0; 3571da177e4SLinus Torvalds 3581da177e4SLinus Torvalds /* 3591da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3601da177e4SLinus Torvalds */ 3617ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 362d594e7ecSAl Viro if (mask == MAY_READ) 36323adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3641da177e4SLinus Torvalds return 0; 3651da177e4SLinus Torvalds 3661da177e4SLinus Torvalds return -EACCES; 3671da177e4SLinus Torvalds } 3684d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3691da177e4SLinus Torvalds 3703ddcd056SLinus Torvalds /* 3713ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3723ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3733ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3743ddcd056SLinus Torvalds * permission function, use the fast case". 3753ddcd056SLinus Torvalds */ 3763ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3773ddcd056SLinus Torvalds { 3783ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3793ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3803ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3813ddcd056SLinus Torvalds 3823ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3833ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3843ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3853ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3863ddcd056SLinus Torvalds } 3873ddcd056SLinus Torvalds return generic_permission(inode, mask); 3883ddcd056SLinus Torvalds } 3893ddcd056SLinus Torvalds 390cb23beb5SChristoph Hellwig /** 3910bdaea90SDavid Howells * __inode_permission - Check for access rights to a given inode 3920bdaea90SDavid Howells * @inode: Inode to check permission on 3930bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 394cb23beb5SChristoph Hellwig * 3950bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. 396948409c7SAndreas Gruenbacher * 397948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 3980bdaea90SDavid Howells * 3990bdaea90SDavid Howells * This does not check for a read-only file system. You probably want 4000bdaea90SDavid Howells * inode_permission(). 401cb23beb5SChristoph Hellwig */ 4020bdaea90SDavid Howells int __inode_permission(struct inode *inode, int mask) 4031da177e4SLinus Torvalds { 404e6305c43SAl Viro int retval; 4051da177e4SLinus Torvalds 4063ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 4071da177e4SLinus Torvalds /* 4081da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 4091da177e4SLinus Torvalds */ 4101da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 4111da177e4SLinus Torvalds return -EACCES; 4121da177e4SLinus Torvalds } 4131da177e4SLinus Torvalds 4143ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 4151da177e4SLinus Torvalds if (retval) 4161da177e4SLinus Torvalds return retval; 4171da177e4SLinus Torvalds 41808ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 41908ce5f16SSerge E. Hallyn if (retval) 42008ce5f16SSerge E. Hallyn return retval; 42108ce5f16SSerge E. Hallyn 422d09ca739SEric Paris return security_inode_permission(inode, mask); 4231da177e4SLinus Torvalds } 424bd5d0856SMiklos Szeredi EXPORT_SYMBOL(__inode_permission); 4251da177e4SLinus Torvalds 426f4d6ff89SAl Viro /** 4270bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 4280bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 42955852635SRandy Dunlap * @inode: Inode to check permission on 4300bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4310bdaea90SDavid Howells * 4320bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4330bdaea90SDavid Howells */ 4340bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4350bdaea90SDavid Howells { 4360bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4370bdaea90SDavid Howells umode_t mode = inode->i_mode; 4380bdaea90SDavid Howells 4390bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 4400bdaea90SDavid Howells if ((sb->s_flags & MS_RDONLY) && 4410bdaea90SDavid Howells (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4420bdaea90SDavid Howells return -EROFS; 4430bdaea90SDavid Howells } 4440bdaea90SDavid Howells return 0; 4450bdaea90SDavid Howells } 4460bdaea90SDavid Howells 4470bdaea90SDavid Howells /** 4480bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4490bdaea90SDavid Howells * @inode: Inode to check permission on 4500bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4510bdaea90SDavid Howells * 4520bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4530bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4540bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4550bdaea90SDavid Howells * 4560bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4570bdaea90SDavid Howells */ 4580bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4590bdaea90SDavid Howells { 4600bdaea90SDavid Howells int retval; 4610bdaea90SDavid Howells 4620bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4630bdaea90SDavid Howells if (retval) 4640bdaea90SDavid Howells return retval; 4650bdaea90SDavid Howells return __inode_permission(inode, mask); 4660bdaea90SDavid Howells } 4674d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4680bdaea90SDavid Howells 4690bdaea90SDavid Howells /** 4705dd784d0SJan Blunck * path_get - get a reference to a path 4715dd784d0SJan Blunck * @path: path to get the reference to 4725dd784d0SJan Blunck * 4735dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4745dd784d0SJan Blunck */ 475dcf787f3SAl Viro void path_get(const struct path *path) 4765dd784d0SJan Blunck { 4775dd784d0SJan Blunck mntget(path->mnt); 4785dd784d0SJan Blunck dget(path->dentry); 4795dd784d0SJan Blunck } 4805dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4815dd784d0SJan Blunck 4825dd784d0SJan Blunck /** 4831d957f9bSJan Blunck * path_put - put a reference to a path 4841d957f9bSJan Blunck * @path: path to put the reference to 4851d957f9bSJan Blunck * 4861d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4871d957f9bSJan Blunck */ 488dcf787f3SAl Viro void path_put(const struct path *path) 4891da177e4SLinus Torvalds { 4901d957f9bSJan Blunck dput(path->dentry); 4911d957f9bSJan Blunck mntput(path->mnt); 4921da177e4SLinus Torvalds } 4931d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4941da177e4SLinus Torvalds 495894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 4961f55a6ecSAl Viro struct nameidata { 4971f55a6ecSAl Viro struct path path; 4981f55a6ecSAl Viro struct qstr last; 4991f55a6ecSAl Viro struct path root; 5001f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 5011f55a6ecSAl Viro unsigned int flags; 5029883d185SAl Viro unsigned seq, m_seq; 5031f55a6ecSAl Viro int last_type; 5041f55a6ecSAl Viro unsigned depth; 505756daf26SNeilBrown int total_link_count; 506697fc6caSAl Viro struct saved { 507697fc6caSAl Viro struct path link; 508fceef393SAl Viro struct delayed_call done; 509697fc6caSAl Viro const char *name; 5100450b2d1SAl Viro unsigned seq; 511894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5129883d185SAl Viro struct filename *name; 5139883d185SAl Viro struct nameidata *saved; 514fceef393SAl Viro struct inode *link_inode; 5159883d185SAl Viro unsigned root_seq; 5169883d185SAl Viro int dfd; 5171f55a6ecSAl Viro }; 5181f55a6ecSAl Viro 5199883d185SAl Viro static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) 520894bc8c4SAl Viro { 521756daf26SNeilBrown struct nameidata *old = current->nameidata; 522756daf26SNeilBrown p->stack = p->internal; 523c8a53ee5SAl Viro p->dfd = dfd; 524c8a53ee5SAl Viro p->name = name; 525756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 5269883d185SAl Viro p->saved = old; 527756daf26SNeilBrown current->nameidata = p; 528894bc8c4SAl Viro } 529894bc8c4SAl Viro 5309883d185SAl Viro static void restore_nameidata(void) 531894bc8c4SAl Viro { 5329883d185SAl Viro struct nameidata *now = current->nameidata, *old = now->saved; 533756daf26SNeilBrown 534756daf26SNeilBrown current->nameidata = old; 535756daf26SNeilBrown if (old) 536756daf26SNeilBrown old->total_link_count = now->total_link_count; 537e1a63bbcSAl Viro if (now->stack != now->internal) 538756daf26SNeilBrown kfree(now->stack); 539894bc8c4SAl Viro } 540894bc8c4SAl Viro 541894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 542894bc8c4SAl Viro { 543bc40aee0SAl Viro struct saved *p; 544bc40aee0SAl Viro 545bc40aee0SAl Viro if (nd->flags & LOOKUP_RCU) { 546bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 547bc40aee0SAl Viro GFP_ATOMIC); 548bc40aee0SAl Viro if (unlikely(!p)) 549bc40aee0SAl Viro return -ECHILD; 550bc40aee0SAl Viro } else { 551bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 552894bc8c4SAl Viro GFP_KERNEL); 553894bc8c4SAl Viro if (unlikely(!p)) 554894bc8c4SAl Viro return -ENOMEM; 555bc40aee0SAl Viro } 556894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 557894bc8c4SAl Viro nd->stack = p; 558894bc8c4SAl Viro return 0; 559894bc8c4SAl Viro } 560894bc8c4SAl Viro 561397d425dSEric W. Biederman /** 562397d425dSEric W. Biederman * path_connected - Verify that a path->dentry is below path->mnt.mnt_root 563397d425dSEric W. Biederman * @path: nameidate to verify 564397d425dSEric W. Biederman * 565397d425dSEric W. Biederman * Rename can sometimes move a file or directory outside of a bind 566397d425dSEric W. Biederman * mount, path_connected allows those cases to be detected. 567397d425dSEric W. Biederman */ 568397d425dSEric W. Biederman static bool path_connected(const struct path *path) 569397d425dSEric W. Biederman { 570397d425dSEric W. Biederman struct vfsmount *mnt = path->mnt; 571397d425dSEric W. Biederman 572397d425dSEric W. Biederman /* Only bind mounts can have disconnected paths */ 573397d425dSEric W. Biederman if (mnt->mnt_root == mnt->mnt_sb->s_root) 574397d425dSEric W. Biederman return true; 575397d425dSEric W. Biederman 576397d425dSEric W. Biederman return is_subdir(path->dentry, mnt->mnt_root); 577397d425dSEric W. Biederman } 578397d425dSEric W. Biederman 579894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 580894bc8c4SAl Viro { 581da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 582894bc8c4SAl Viro return 0; 583894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 584894bc8c4SAl Viro return 0; 585894bc8c4SAl Viro return __nd_alloc_stack(nd); 586894bc8c4SAl Viro } 587894bc8c4SAl Viro 5887973387aSAl Viro static void drop_links(struct nameidata *nd) 5897973387aSAl Viro { 5907973387aSAl Viro int i = nd->depth; 5917973387aSAl Viro while (i--) { 5927973387aSAl Viro struct saved *last = nd->stack + i; 593fceef393SAl Viro do_delayed_call(&last->done); 594fceef393SAl Viro clear_delayed_call(&last->done); 5957973387aSAl Viro } 5967973387aSAl Viro } 5977973387aSAl Viro 5987973387aSAl Viro static void terminate_walk(struct nameidata *nd) 5997973387aSAl Viro { 6007973387aSAl Viro drop_links(nd); 6017973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 6027973387aSAl Viro int i; 6037973387aSAl Viro path_put(&nd->path); 6047973387aSAl Viro for (i = 0; i < nd->depth; i++) 6057973387aSAl Viro path_put(&nd->stack[i].link); 606102b8af2SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 607102b8af2SAl Viro path_put(&nd->root); 608102b8af2SAl Viro nd->root.mnt = NULL; 609102b8af2SAl Viro } 6107973387aSAl Viro } else { 6117973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 6127973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6137973387aSAl Viro nd->root.mnt = NULL; 6147973387aSAl Viro rcu_read_unlock(); 6157973387aSAl Viro } 6167973387aSAl Viro nd->depth = 0; 6177973387aSAl Viro } 6187973387aSAl Viro 6197973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 6207973387aSAl Viro static bool legitimize_path(struct nameidata *nd, 6217973387aSAl Viro struct path *path, unsigned seq) 6227973387aSAl Viro { 6237973387aSAl Viro int res = __legitimize_mnt(path->mnt, nd->m_seq); 6247973387aSAl Viro if (unlikely(res)) { 6257973387aSAl Viro if (res > 0) 6267973387aSAl Viro path->mnt = NULL; 6277973387aSAl Viro path->dentry = NULL; 6287973387aSAl Viro return false; 6297973387aSAl Viro } 6307973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 6317973387aSAl Viro path->dentry = NULL; 6327973387aSAl Viro return false; 6337973387aSAl Viro } 6347973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6357973387aSAl Viro } 6367973387aSAl Viro 6377973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6387973387aSAl Viro { 6397973387aSAl Viro int i; 6407973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6417973387aSAl Viro struct saved *last = nd->stack + i; 6427973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6437973387aSAl Viro drop_links(nd); 6447973387aSAl Viro nd->depth = i + 1; 6457973387aSAl Viro return false; 6467973387aSAl Viro } 6477973387aSAl Viro } 6487973387aSAl Viro return true; 6497973387aSAl Viro } 6507973387aSAl Viro 65119660af7SAl Viro /* 65231e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 65319660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 65419660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 65557e3715cSMike Marshall * normal reference counts on dentries and vfsmounts to transition to ref-walk 65619660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 65719660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 65819660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 65919660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 66031e6b01fSNick Piggin */ 66131e6b01fSNick Piggin 66231e6b01fSNick Piggin /** 66319660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 66419660af7SAl Viro * @nd: nameidata pathwalk data 66519660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 6666e9918b7SAl Viro * @seq: seq number to check dentry against 66739191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 66831e6b01fSNick Piggin * 66919660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 67019660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 67119660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 6727973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6737973387aSAl Viro * terminate_walk(). 67431e6b01fSNick Piggin */ 6756e9918b7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry, unsigned seq) 67631e6b01fSNick Piggin { 67731e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 67831e6b01fSNick Piggin 67931e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 680e5c832d5SLinus Torvalds 681e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6827973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6837973387aSAl Viro goto out2; 6847973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 6857973387aSAl Viro goto out2; 6867973387aSAl Viro if (unlikely(!lockref_get_not_dead(&parent->d_lockref))) 6877973387aSAl Viro goto out1; 68848a066e7SAl Viro 68915570086SLinus Torvalds /* 69015570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 69115570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 69215570086SLinus Torvalds * 69315570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 69415570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 69515570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 69615570086SLinus Torvalds * since we checked the sequence number of the parent after we got 69715570086SLinus Torvalds * the child sequence number. So we know the parent must still 69815570086SLinus Torvalds * be valid if the child sequence number is still valid. 69915570086SLinus Torvalds */ 70019660af7SAl Viro if (!dentry) { 701e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 702e5c832d5SLinus Torvalds goto out; 70319660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 70419660af7SAl Viro } else { 705e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 706e5c832d5SLinus Torvalds goto out; 7076e9918b7SAl Viro if (read_seqcount_retry(&dentry->d_seq, seq)) 708e5c832d5SLinus Torvalds goto drop_dentry; 70919660af7SAl Viro } 710e5c832d5SLinus Torvalds 711e5c832d5SLinus Torvalds /* 712e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 713e5c832d5SLinus Torvalds * still valid and get it if required. 714e5c832d5SLinus Torvalds */ 715e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 7165a8d87e8SAl Viro if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq))) { 7175a8d87e8SAl Viro rcu_read_unlock(); 7185a8d87e8SAl Viro dput(dentry); 7195a8d87e8SAl Viro return -ECHILD; 7207973387aSAl Viro } 72131e6b01fSNick Piggin } 72231e6b01fSNick Piggin 7238b61e74fSAl Viro rcu_read_unlock(); 72431e6b01fSNick Piggin return 0; 72519660af7SAl Viro 726e5c832d5SLinus Torvalds drop_dentry: 7278b61e74fSAl Viro rcu_read_unlock(); 728e5c832d5SLinus Torvalds dput(dentry); 729d0d27277SLinus Torvalds goto drop_root_mnt; 7307973387aSAl Viro out2: 7317973387aSAl Viro nd->path.mnt = NULL; 7327973387aSAl Viro out1: 7337973387aSAl Viro nd->path.dentry = NULL; 734e5c832d5SLinus Torvalds out: 7358b61e74fSAl Viro rcu_read_unlock(); 736d0d27277SLinus Torvalds drop_root_mnt: 737d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 738d0d27277SLinus Torvalds nd->root.mnt = NULL; 73931e6b01fSNick Piggin return -ECHILD; 74031e6b01fSNick Piggin } 74131e6b01fSNick Piggin 7427973387aSAl Viro static int unlazy_link(struct nameidata *nd, struct path *link, unsigned seq) 7437973387aSAl Viro { 7447973387aSAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 7457973387aSAl Viro drop_links(nd); 7467973387aSAl Viro nd->depth = 0; 7477973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 7487973387aSAl Viro nd->path.mnt = NULL; 7497973387aSAl Viro nd->path.dentry = NULL; 7507973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7517973387aSAl Viro nd->root.mnt = NULL; 7527973387aSAl Viro rcu_read_unlock(); 7537973387aSAl Viro } else if (likely(unlazy_walk(nd, NULL, 0)) == 0) { 7547973387aSAl Viro return 0; 7557973387aSAl Viro } 7567973387aSAl Viro path_put(link); 7577973387aSAl Viro return -ECHILD; 7587973387aSAl Viro } 7597973387aSAl Viro 7604ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 76134286d66SNick Piggin { 7624ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 76334286d66SNick Piggin } 76434286d66SNick Piggin 7659f1fafeeSAl Viro /** 7669f1fafeeSAl Viro * complete_walk - successful completion of path walk 7679f1fafeeSAl Viro * @nd: pointer nameidata 76839159de2SJeff Layton * 7699f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7709f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7719f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7729f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7739f1fafeeSAl Viro * need to drop nd->path. 77439159de2SJeff Layton */ 7759f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 77639159de2SJeff Layton { 77716c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 77839159de2SJeff Layton int status; 77939159de2SJeff Layton 7809f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 7819f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7829f1fafeeSAl Viro nd->root.mnt = NULL; 7836e9918b7SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 78448a066e7SAl Viro return -ECHILD; 78548a066e7SAl Viro } 7869f1fafeeSAl Viro 78716c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 78839159de2SJeff Layton return 0; 78939159de2SJeff Layton 790ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 79116c2cd71SAl Viro return 0; 79216c2cd71SAl Viro 793ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 79439159de2SJeff Layton if (status > 0) 79539159de2SJeff Layton return 0; 79639159de2SJeff Layton 79716c2cd71SAl Viro if (!status) 79839159de2SJeff Layton status = -ESTALE; 79916c2cd71SAl Viro 80039159de2SJeff Layton return status; 80139159de2SJeff Layton } 80239159de2SJeff Layton 80318d8c860SAl Viro static void set_root(struct nameidata *nd) 8042a737871SAl Viro { 80531e6b01fSNick Piggin struct fs_struct *fs = current->fs; 8069e6697e2SAl Viro 8079e6697e2SAl Viro if (nd->flags & LOOKUP_RCU) { 8088f47a016SAl Viro unsigned seq; 809c28cc364SNick Piggin 810c28cc364SNick Piggin do { 811c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 81231e6b01fSNick Piggin nd->root = fs->root; 8138f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 814c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 8159e6697e2SAl Viro } else { 8169e6697e2SAl Viro get_fs_root(fs, &nd->root); 8179e6697e2SAl Viro } 81831e6b01fSNick Piggin } 81931e6b01fSNick Piggin 8201d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 821051d3812SIan Kent { 822051d3812SIan Kent dput(path->dentry); 8234ac91378SJan Blunck if (path->mnt != nd->path.mnt) 824051d3812SIan Kent mntput(path->mnt); 825051d3812SIan Kent } 826051d3812SIan Kent 8277b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8287b9337aaSNick Piggin struct nameidata *nd) 829051d3812SIan Kent { 83031e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8314ac91378SJan Blunck dput(nd->path.dentry); 83231e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8334ac91378SJan Blunck mntput(nd->path.mnt); 8349a229683SHuang Shijie } 83531e6b01fSNick Piggin nd->path.mnt = path->mnt; 8364ac91378SJan Blunck nd->path.dentry = path->dentry; 837051d3812SIan Kent } 838051d3812SIan Kent 839248fb5b9SAl Viro static int nd_jump_root(struct nameidata *nd) 840248fb5b9SAl Viro { 841248fb5b9SAl Viro if (nd->flags & LOOKUP_RCU) { 842248fb5b9SAl Viro struct dentry *d; 843248fb5b9SAl Viro nd->path = nd->root; 844248fb5b9SAl Viro d = nd->path.dentry; 845248fb5b9SAl Viro nd->inode = d->d_inode; 846248fb5b9SAl Viro nd->seq = nd->root_seq; 847248fb5b9SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 848248fb5b9SAl Viro return -ECHILD; 849248fb5b9SAl Viro } else { 850248fb5b9SAl Viro path_put(&nd->path); 851248fb5b9SAl Viro nd->path = nd->root; 852248fb5b9SAl Viro path_get(&nd->path); 853248fb5b9SAl Viro nd->inode = nd->path.dentry->d_inode; 854248fb5b9SAl Viro } 855248fb5b9SAl Viro nd->flags |= LOOKUP_JUMPED; 856248fb5b9SAl Viro return 0; 857248fb5b9SAl Viro } 858248fb5b9SAl Viro 859b5fb63c1SChristoph Hellwig /* 8606b255391SAl Viro * Helper to directly jump to a known parsed path from ->get_link, 861b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 862b5fb63c1SChristoph Hellwig */ 8636e77137bSAl Viro void nd_jump_link(struct path *path) 864b5fb63c1SChristoph Hellwig { 8656e77137bSAl Viro struct nameidata *nd = current->nameidata; 866b5fb63c1SChristoph Hellwig path_put(&nd->path); 867b5fb63c1SChristoph Hellwig 868b5fb63c1SChristoph Hellwig nd->path = *path; 869b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 870b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 871b5fb63c1SChristoph Hellwig } 872b5fb63c1SChristoph Hellwig 873b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 874574197e0SAl Viro { 87521c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 876fceef393SAl Viro do_delayed_call(&last->done); 8776548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 878b9ff4429SAl Viro path_put(&last->link); 879574197e0SAl Viro } 880574197e0SAl Viro 881561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 882561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 883800179c9SKees Cook 884800179c9SKees Cook /** 885800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 88655852635SRandy Dunlap * @nd: nameidata pathwalk data 887800179c9SKees Cook * 888800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 889800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 890800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 891800179c9SKees Cook * processes from failing races against path names that may change out 892800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 893800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 894800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 895800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 896800179c9SKees Cook * 897800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 898800179c9SKees Cook */ 899fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 900800179c9SKees Cook { 901800179c9SKees Cook const struct inode *inode; 902800179c9SKees Cook const struct inode *parent; 903800179c9SKees Cook 904800179c9SKees Cook if (!sysctl_protected_symlinks) 905800179c9SKees Cook return 0; 906800179c9SKees Cook 907800179c9SKees Cook /* Allowed if owner and follower match. */ 908fceef393SAl Viro inode = nd->link_inode; 90981abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 910800179c9SKees Cook return 0; 911800179c9SKees Cook 912800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 913aa65fa35SAl Viro parent = nd->inode; 914800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 915800179c9SKees Cook return 0; 916800179c9SKees Cook 917800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 91881abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 919800179c9SKees Cook return 0; 920800179c9SKees Cook 92131956502SAl Viro if (nd->flags & LOOKUP_RCU) 92231956502SAl Viro return -ECHILD; 92331956502SAl Viro 9241cf2665bSAl Viro audit_log_link_denied("follow_link", &nd->stack[0].link); 925800179c9SKees Cook return -EACCES; 926800179c9SKees Cook } 927800179c9SKees Cook 928800179c9SKees Cook /** 929800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 930800179c9SKees Cook * @inode: the source inode to hardlink from 931800179c9SKees Cook * 932800179c9SKees Cook * Return false if at least one of the following conditions: 933800179c9SKees Cook * - inode is not a regular file 934800179c9SKees Cook * - inode is setuid 935800179c9SKees Cook * - inode is setgid and group-exec 936800179c9SKees Cook * - access failure for read and write 937800179c9SKees Cook * 938800179c9SKees Cook * Otherwise returns true. 939800179c9SKees Cook */ 940800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 941800179c9SKees Cook { 942800179c9SKees Cook umode_t mode = inode->i_mode; 943800179c9SKees Cook 944800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 945800179c9SKees Cook if (!S_ISREG(mode)) 946800179c9SKees Cook return false; 947800179c9SKees Cook 948800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 949800179c9SKees Cook if (mode & S_ISUID) 950800179c9SKees Cook return false; 951800179c9SKees Cook 952800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 953800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 954800179c9SKees Cook return false; 955800179c9SKees Cook 956800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 957800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 958800179c9SKees Cook return false; 959800179c9SKees Cook 960800179c9SKees Cook return true; 961800179c9SKees Cook } 962800179c9SKees Cook 963800179c9SKees Cook /** 964800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 965800179c9SKees Cook * @link: the source to hardlink from 966800179c9SKees Cook * 967800179c9SKees Cook * Block hardlink when all of: 968800179c9SKees Cook * - sysctl_protected_hardlinks enabled 969800179c9SKees Cook * - fsuid does not match inode 970800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 971f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 972800179c9SKees Cook * 973800179c9SKees Cook * Returns 0 if successful, -ve on error. 974800179c9SKees Cook */ 975800179c9SKees Cook static int may_linkat(struct path *link) 976800179c9SKees Cook { 977800179c9SKees Cook struct inode *inode; 978800179c9SKees Cook 979800179c9SKees Cook if (!sysctl_protected_hardlinks) 980800179c9SKees Cook return 0; 981800179c9SKees Cook 982800179c9SKees Cook inode = link->dentry->d_inode; 983800179c9SKees Cook 984800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 985800179c9SKees Cook * otherwise, it must be a safe source. 986800179c9SKees Cook */ 987f2ca3796SDirk Steinmetz if (inode_owner_or_capable(inode) || safe_hardlink_source(inode)) 988800179c9SKees Cook return 0; 989800179c9SKees Cook 990a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 991800179c9SKees Cook return -EPERM; 992800179c9SKees Cook } 993800179c9SKees Cook 9943b2e7f75SAl Viro static __always_inline 9953b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 9961da177e4SLinus Torvalds { 997ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 9981cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 999fceef393SAl Viro struct inode *inode = nd->link_inode; 10006d7b5aaeSAl Viro int error; 10010a959df5SAl Viro const char *res; 10021da177e4SLinus Torvalds 10038fa9dd24SNeilBrown if (!(nd->flags & LOOKUP_RCU)) { 10048fa9dd24SNeilBrown touch_atime(&last->link); 10058fa9dd24SNeilBrown cond_resched(); 10068fa9dd24SNeilBrown } else if (atime_needs_update(&last->link, inode)) { 10078fa9dd24SNeilBrown if (unlikely(unlazy_walk(nd, NULL, 0))) 10088fa9dd24SNeilBrown return ERR_PTR(-ECHILD); 10098fa9dd24SNeilBrown touch_atime(&last->link); 10108fa9dd24SNeilBrown } 10118fa9dd24SNeilBrown 1012bda0be7aSNeilBrown error = security_inode_follow_link(dentry, inode, 1013bda0be7aSNeilBrown nd->flags & LOOKUP_RCU); 1014bda0be7aSNeilBrown if (unlikely(error)) 10156920a440SAl Viro return ERR_PTR(error); 101636f3b4f6SAl Viro 101786acdca1SAl Viro nd->last_type = LAST_BIND; 1018d4dee48bSAl Viro res = inode->i_link; 1019d4dee48bSAl Viro if (!res) { 1020fceef393SAl Viro const char * (*get)(struct dentry *, struct inode *, 1021fceef393SAl Viro struct delayed_call *); 1022fceef393SAl Viro get = inode->i_op->get_link; 10238c1b4566SAl Viro if (nd->flags & LOOKUP_RCU) { 1024fceef393SAl Viro res = get(NULL, inode, &last->done); 10256b255391SAl Viro if (res == ERR_PTR(-ECHILD)) { 10268c1b4566SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 10278c1b4566SAl Viro return ERR_PTR(-ECHILD); 1028fceef393SAl Viro res = get(dentry, inode, &last->done); 10298c1b4566SAl Viro } 10306b255391SAl Viro } else { 1031fceef393SAl Viro res = get(dentry, inode, &last->done); 10326b255391SAl Viro } 1033fceef393SAl Viro if (IS_ERR_OR_NULL(res)) 1034fab51e8aSAl Viro return res; 10350a959df5SAl Viro } 1036fab51e8aSAl Viro if (*res == '/') { 1037fab51e8aSAl Viro if (!nd->root.mnt) 1038fab51e8aSAl Viro set_root(nd); 1039248fb5b9SAl Viro if (unlikely(nd_jump_root(nd))) 1040fab51e8aSAl Viro return ERR_PTR(-ECHILD); 1041fab51e8aSAl Viro while (unlikely(*++res == '/')) 1042fab51e8aSAl Viro ; 1043fab51e8aSAl Viro } 1044fab51e8aSAl Viro if (!*res) 1045fab51e8aSAl Viro res = NULL; 10460a959df5SAl Viro return res; 10470a959df5SAl Viro } 10486d7b5aaeSAl Viro 1049f015f126SDavid Howells /* 1050f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1051f015f126SDavid Howells * 1052f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1053f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1054f015f126SDavid Howells * Up is towards /. 1055f015f126SDavid Howells * 1056f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1057f015f126SDavid Howells * root. 1058f015f126SDavid Howells */ 1059bab77ebfSAl Viro int follow_up(struct path *path) 10601da177e4SLinus Torvalds { 10610714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 10620714a533SAl Viro struct mount *parent; 10631da177e4SLinus Torvalds struct dentry *mountpoint; 106499b7db7bSNick Piggin 106548a066e7SAl Viro read_seqlock_excl(&mount_lock); 10660714a533SAl Viro parent = mnt->mnt_parent; 10673c0a6163SAl Viro if (parent == mnt) { 106848a066e7SAl Viro read_sequnlock_excl(&mount_lock); 10691da177e4SLinus Torvalds return 0; 10701da177e4SLinus Torvalds } 10710714a533SAl Viro mntget(&parent->mnt); 1072a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 107348a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1074bab77ebfSAl Viro dput(path->dentry); 1075bab77ebfSAl Viro path->dentry = mountpoint; 1076bab77ebfSAl Viro mntput(path->mnt); 10770714a533SAl Viro path->mnt = &parent->mnt; 10781da177e4SLinus Torvalds return 1; 10791da177e4SLinus Torvalds } 10804d359507SAl Viro EXPORT_SYMBOL(follow_up); 10811da177e4SLinus Torvalds 1082b5c84bf6SNick Piggin /* 10839875cf80SDavid Howells * Perform an automount 10849875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 10859875cf80SDavid Howells * were called with. 10861da177e4SLinus Torvalds */ 1087756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 10889875cf80SDavid Howells bool *need_mntput) 108931e6b01fSNick Piggin { 10909875cf80SDavid Howells struct vfsmount *mnt; 1091ea5b778aSDavid Howells int err; 10929875cf80SDavid Howells 10939875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 10949875cf80SDavid Howells return -EREMOTE; 10959875cf80SDavid Howells 10960ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 10970ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 10980ec26fd0SMiklos Szeredi * the name. 10990ec26fd0SMiklos Szeredi * 11000ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 11015a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 11020ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 11030ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 11040ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 11050ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 11065a30d8a2SDavid Howells */ 1107756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 1108d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 11095a30d8a2SDavid Howells path->dentry->d_inode) 11109875cf80SDavid Howells return -EISDIR; 11110ec26fd0SMiklos Szeredi 1112756daf26SNeilBrown nd->total_link_count++; 1113756daf26SNeilBrown if (nd->total_link_count >= 40) 11149875cf80SDavid Howells return -ELOOP; 11159875cf80SDavid Howells 11169875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 11179875cf80SDavid Howells if (IS_ERR(mnt)) { 11189875cf80SDavid Howells /* 11199875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 11209875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 11219875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 11229875cf80SDavid Howells * 11239875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 11249875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 11259875cf80SDavid Howells * the path is inaccessible and we should say so. 11269875cf80SDavid Howells */ 1127756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 11289875cf80SDavid Howells return -EREMOTE; 11299875cf80SDavid Howells return PTR_ERR(mnt); 113031e6b01fSNick Piggin } 1131ea5b778aSDavid Howells 11329875cf80SDavid Howells if (!mnt) /* mount collision */ 11339875cf80SDavid Howells return 0; 11349875cf80SDavid Howells 11358aef1884SAl Viro if (!*need_mntput) { 11368aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 11378aef1884SAl Viro mntget(path->mnt); 11388aef1884SAl Viro *need_mntput = true; 11398aef1884SAl Viro } 114019a167afSAl Viro err = finish_automount(mnt, path); 1141ea5b778aSDavid Howells 1142ea5b778aSDavid Howells switch (err) { 1143ea5b778aSDavid Howells case -EBUSY: 1144ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 114519a167afSAl Viro return 0; 1146ea5b778aSDavid Howells case 0: 11478aef1884SAl Viro path_put(path); 11489875cf80SDavid Howells path->mnt = mnt; 11499875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 11509875cf80SDavid Howells return 0; 115119a167afSAl Viro default: 115219a167afSAl Viro return err; 11539875cf80SDavid Howells } 115419a167afSAl Viro 1155ea5b778aSDavid Howells } 11569875cf80SDavid Howells 11579875cf80SDavid Howells /* 11589875cf80SDavid Howells * Handle a dentry that is managed in some way. 1159cc53ce53SDavid Howells * - Flagged for transit management (autofs) 11609875cf80SDavid Howells * - Flagged as mountpoint 11619875cf80SDavid Howells * - Flagged as automount point 11629875cf80SDavid Howells * 11639875cf80SDavid Howells * This may only be called in refwalk mode. 11649875cf80SDavid Howells * 11659875cf80SDavid Howells * Serialization is taken care of in namespace.c 11669875cf80SDavid Howells */ 1167756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 11689875cf80SDavid Howells { 11698aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 11709875cf80SDavid Howells unsigned managed; 11719875cf80SDavid Howells bool need_mntput = false; 11728aef1884SAl Viro int ret = 0; 11739875cf80SDavid Howells 11749875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 11759875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 11769875cf80SDavid Howells * the components of that value change under us */ 11779875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 11789875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 11799875cf80SDavid Howells unlikely(managed != 0)) { 1180cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1181cc53ce53SDavid Howells * being held. */ 1182cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1183cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1184cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 11851aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1186cc53ce53SDavid Howells if (ret < 0) 11878aef1884SAl Viro break; 1188cc53ce53SDavid Howells } 1189cc53ce53SDavid Howells 11909875cf80SDavid Howells /* Transit to a mounted filesystem. */ 11919875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 11929875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 11939875cf80SDavid Howells if (mounted) { 11949875cf80SDavid Howells dput(path->dentry); 11959875cf80SDavid Howells if (need_mntput) 1196463ffb2eSAl Viro mntput(path->mnt); 1197463ffb2eSAl Viro path->mnt = mounted; 1198463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 11999875cf80SDavid Howells need_mntput = true; 12009875cf80SDavid Howells continue; 1201463ffb2eSAl Viro } 1202463ffb2eSAl Viro 12039875cf80SDavid Howells /* Something is mounted on this dentry in another 12049875cf80SDavid Howells * namespace and/or whatever was mounted there in this 120548a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 120648a066e7SAl Viro * get it */ 12071da177e4SLinus Torvalds } 12089875cf80SDavid Howells 12099875cf80SDavid Howells /* Handle an automount point */ 12109875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1211756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 12129875cf80SDavid Howells if (ret < 0) 12138aef1884SAl Viro break; 12149875cf80SDavid Howells continue; 12159875cf80SDavid Howells } 12169875cf80SDavid Howells 12179875cf80SDavid Howells /* We didn't change the current path point */ 12189875cf80SDavid Howells break; 12199875cf80SDavid Howells } 12208aef1884SAl Viro 12218aef1884SAl Viro if (need_mntput && path->mnt == mnt) 12228aef1884SAl Viro mntput(path->mnt); 1223e9742b53SAl Viro if (ret == -EISDIR || !ret) 1224e9742b53SAl Viro ret = 1; 12258402752eSAl Viro if (need_mntput) 12268402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 12278402752eSAl Viro if (unlikely(ret < 0)) 12288402752eSAl Viro path_put_conditional(path, nd); 12298402752eSAl Viro return ret; 12301da177e4SLinus Torvalds } 12311da177e4SLinus Torvalds 1232cc53ce53SDavid Howells int follow_down_one(struct path *path) 12331da177e4SLinus Torvalds { 12341da177e4SLinus Torvalds struct vfsmount *mounted; 12351da177e4SLinus Torvalds 12361c755af4SAl Viro mounted = lookup_mnt(path); 12371da177e4SLinus Torvalds if (mounted) { 12389393bd07SAl Viro dput(path->dentry); 12399393bd07SAl Viro mntput(path->mnt); 12409393bd07SAl Viro path->mnt = mounted; 12419393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12421da177e4SLinus Torvalds return 1; 12431da177e4SLinus Torvalds } 12441da177e4SLinus Torvalds return 0; 12451da177e4SLinus Torvalds } 12464d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12471da177e4SLinus Torvalds 1248b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 124962a7375eSIan Kent { 1250b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1251b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 125262a7375eSIan Kent } 125362a7375eSIan Kent 12549875cf80SDavid Howells /* 1255287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1256287548e4SAl Viro * we meet a managed dentry that would need blocking. 12579875cf80SDavid Howells */ 12589875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1259254cf582SAl Viro struct inode **inode, unsigned *seqp) 12609875cf80SDavid Howells { 126162a7375eSIan Kent for (;;) { 1262c7105365SAl Viro struct mount *mounted; 126362a7375eSIan Kent /* 126462a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 126562a7375eSIan Kent * that wants to block transit. 126662a7375eSIan Kent */ 1267b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1268b8faf035SNeilBrown case -ECHILD: 1269b8faf035SNeilBrown default: 1270ab90911fSDavid Howells return false; 1271b8faf035SNeilBrown case -EISDIR: 1272b8faf035SNeilBrown return true; 1273b8faf035SNeilBrown case 0: 1274b8faf035SNeilBrown break; 1275b8faf035SNeilBrown } 127662a7375eSIan Kent 127762a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1278b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 127962a7375eSIan Kent 1280474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 12819875cf80SDavid Howells if (!mounted) 12829875cf80SDavid Howells break; 1283c7105365SAl Viro path->mnt = &mounted->mnt; 1284c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1285a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1286254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 128759430262SLinus Torvalds /* 128859430262SLinus Torvalds * Update the inode too. We don't need to re-check the 128959430262SLinus Torvalds * dentry sequence number here after this d_inode read, 129059430262SLinus Torvalds * because a mount-point is always pinned. 129159430262SLinus Torvalds */ 129259430262SLinus Torvalds *inode = path->dentry->d_inode; 12939875cf80SDavid Howells } 1294f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1295b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1296287548e4SAl Viro } 1297287548e4SAl Viro 129831e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 129931e6b01fSNick Piggin { 13004023bfc9SAl Viro struct inode *inode = nd->inode; 130131e6b01fSNick Piggin 130231e6b01fSNick Piggin while (1) { 1303aed434adSAl Viro if (path_equal(&nd->path, &nd->root)) 130431e6b01fSNick Piggin break; 130531e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 130631e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 130731e6b01fSNick Piggin struct dentry *parent = old->d_parent; 130831e6b01fSNick Piggin unsigned seq; 130931e6b01fSNick Piggin 13104023bfc9SAl Viro inode = parent->d_inode; 131131e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 1312aed434adSAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 1313aed434adSAl Viro return -ECHILD; 131431e6b01fSNick Piggin nd->path.dentry = parent; 131531e6b01fSNick Piggin nd->seq = seq; 1316397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 1317397d425dSEric W. Biederman return -ENOENT; 131831e6b01fSNick Piggin break; 1319aed434adSAl Viro } else { 1320aed434adSAl Viro struct mount *mnt = real_mount(nd->path.mnt); 1321aed434adSAl Viro struct mount *mparent = mnt->mnt_parent; 1322aed434adSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1323aed434adSAl Viro struct inode *inode2 = mountpoint->d_inode; 1324aed434adSAl Viro unsigned seq = read_seqcount_begin(&mountpoint->d_seq); 1325aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1326aed434adSAl Viro return -ECHILD; 1327aed434adSAl Viro if (&mparent->mnt == nd->path.mnt) 132831e6b01fSNick Piggin break; 1329aed434adSAl Viro /* we know that mountpoint was pinned */ 1330aed434adSAl Viro nd->path.dentry = mountpoint; 1331aed434adSAl Viro nd->path.mnt = &mparent->mnt; 1332aed434adSAl Viro inode = inode2; 1333aed434adSAl Viro nd->seq = seq; 133431e6b01fSNick Piggin } 1335aed434adSAl Viro } 1336aed434adSAl Viro while (unlikely(d_mountpoint(nd->path.dentry))) { 1337b37199e6SAl Viro struct mount *mounted; 1338b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1339aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1340aed434adSAl Viro return -ECHILD; 1341b37199e6SAl Viro if (!mounted) 1342b37199e6SAl Viro break; 1343b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1344b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 13454023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1346b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1347b37199e6SAl Viro } 13484023bfc9SAl Viro nd->inode = inode; 134931e6b01fSNick Piggin return 0; 135031e6b01fSNick Piggin } 135131e6b01fSNick Piggin 13529875cf80SDavid Howells /* 1353cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1354cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1355cc53ce53SDavid Howells * caller is permitted to proceed or not. 1356cc53ce53SDavid Howells */ 13577cc90cc3SAl Viro int follow_down(struct path *path) 1358cc53ce53SDavid Howells { 1359cc53ce53SDavid Howells unsigned managed; 1360cc53ce53SDavid Howells int ret; 1361cc53ce53SDavid Howells 1362cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1363cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1364cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1365cc53ce53SDavid Howells * being held. 1366cc53ce53SDavid Howells * 1367cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1368cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1369cc53ce53SDavid Howells * other than its daemon the right to mount on its 1370cc53ce53SDavid Howells * superstructure. 1371cc53ce53SDavid Howells * 1372cc53ce53SDavid Howells * The filesystem may sleep at this point. 1373cc53ce53SDavid Howells */ 1374cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1375cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1376cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1377ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 13781aed3e42SAl Viro path->dentry, false); 1379cc53ce53SDavid Howells if (ret < 0) 1380cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1381cc53ce53SDavid Howells } 1382cc53ce53SDavid Howells 1383cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1384cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1385cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1386cc53ce53SDavid Howells if (!mounted) 1387cc53ce53SDavid Howells break; 1388cc53ce53SDavid Howells dput(path->dentry); 1389cc53ce53SDavid Howells mntput(path->mnt); 1390cc53ce53SDavid Howells path->mnt = mounted; 1391cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1392cc53ce53SDavid Howells continue; 1393cc53ce53SDavid Howells } 1394cc53ce53SDavid Howells 1395cc53ce53SDavid Howells /* Don't handle automount points here */ 1396cc53ce53SDavid Howells break; 1397cc53ce53SDavid Howells } 1398cc53ce53SDavid Howells return 0; 1399cc53ce53SDavid Howells } 14004d359507SAl Viro EXPORT_SYMBOL(follow_down); 1401cc53ce53SDavid Howells 1402cc53ce53SDavid Howells /* 14039875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 14049875cf80SDavid Howells */ 14059875cf80SDavid Howells static void follow_mount(struct path *path) 14069875cf80SDavid Howells { 14079875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 14089875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 14099875cf80SDavid Howells if (!mounted) 14109875cf80SDavid Howells break; 14119875cf80SDavid Howells dput(path->dentry); 14129875cf80SDavid Howells mntput(path->mnt); 14139875cf80SDavid Howells path->mnt = mounted; 14149875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 14159875cf80SDavid Howells } 14169875cf80SDavid Howells } 14179875cf80SDavid Howells 1418397d425dSEric W. Biederman static int follow_dotdot(struct nameidata *nd) 14191da177e4SLinus Torvalds { 14201da177e4SLinus Torvalds while(1) { 14214ac91378SJan Blunck struct dentry *old = nd->path.dentry; 14221da177e4SLinus Torvalds 14232a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 14242a737871SAl Viro nd->path.mnt == nd->root.mnt) { 14251da177e4SLinus Torvalds break; 14261da177e4SLinus Torvalds } 14274ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 14283088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 14293088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 14301da177e4SLinus Torvalds dput(old); 1431397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 1432397d425dSEric W. Biederman return -ENOENT; 14331da177e4SLinus Torvalds break; 14341da177e4SLinus Torvalds } 14353088dd70SAl Viro if (!follow_up(&nd->path)) 14361da177e4SLinus Torvalds break; 14371da177e4SLinus Torvalds } 143879ed0226SAl Viro follow_mount(&nd->path); 143931e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 1440397d425dSEric W. Biederman return 0; 14411da177e4SLinus Torvalds } 14421da177e4SLinus Torvalds 14431da177e4SLinus Torvalds /* 1444bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1445bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1446bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1447baa03890SNick Piggin */ 1448e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1449e3c13928SAl Viro struct dentry *dir, 14506c51e513SAl Viro unsigned int flags) 1451baa03890SNick Piggin { 1452baa03890SNick Piggin struct dentry *dentry; 1453bad61189SMiklos Szeredi int error; 1454baa03890SNick Piggin 1455bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1456bad61189SMiklos Szeredi if (dentry) { 145739e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1458201f956eSAl Viro error = d_revalidate(dentry, flags); 1459bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 146074ff0ffcSAl Viro if (!error) 14615542aa2fSEric W. Biederman d_invalidate(dentry); 1462bad61189SMiklos Szeredi dput(dentry); 146374ff0ffcSAl Viro return ERR_PTR(error); 1464bad61189SMiklos Szeredi } 1465bad61189SMiklos Szeredi } 1466bad61189SMiklos Szeredi } 1467baa03890SNick Piggin return dentry; 1468baa03890SNick Piggin } 1469baa03890SNick Piggin 1470baa03890SNick Piggin /* 147113a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 147213a2c3beSJ. Bruce Fields * unhashed. 1473bad61189SMiklos Szeredi * 1474bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 147544396f4bSJosef Bacik */ 1476bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 147772bd866aSAl Viro unsigned int flags) 147844396f4bSJosef Bacik { 147944396f4bSJosef Bacik struct dentry *old; 148044396f4bSJosef Bacik 148144396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1482bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1483e188dc02SMiklos Szeredi dput(dentry); 148444396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1485e188dc02SMiklos Szeredi } 148644396f4bSJosef Bacik 148772bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 148844396f4bSJosef Bacik if (unlikely(old)) { 148944396f4bSJosef Bacik dput(dentry); 149044396f4bSJosef Bacik dentry = old; 149144396f4bSJosef Bacik } 149244396f4bSJosef Bacik return dentry; 149344396f4bSJosef Bacik } 149444396f4bSJosef Bacik 1495e3c13928SAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 149672bd866aSAl Viro struct dentry *base, unsigned int flags) 1497a3255546SAl Viro { 14986c51e513SAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 1499a3255546SAl Viro 15006c51e513SAl Viro if (dentry) 1501a3255546SAl Viro return dentry; 1502bad61189SMiklos Szeredi 15036c51e513SAl Viro dentry = d_alloc(base, name); 15046c51e513SAl Viro if (unlikely(!dentry)) 15056c51e513SAl Viro return ERR_PTR(-ENOMEM); 15066c51e513SAl Viro 150772bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1508a3255546SAl Viro } 1509a3255546SAl Viro 1510e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 1511254cf582SAl Viro struct path *path, struct inode **inode, 1512254cf582SAl Viro unsigned *seqp) 15131da177e4SLinus Torvalds { 15144ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 151531e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 15165a18fff2SAl Viro int status = 1; 15179875cf80SDavid Howells int err; 15189875cf80SDavid Howells 15193cac260aSAl Viro /* 1520b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 15215d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 15225d0f49c1SAl Viro * going to fall back to non-racy lookup. 1523b04f784eSNick Piggin */ 152431e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 152531e6b01fSNick Piggin unsigned seq; 1526766c4cbfSAl Viro bool negative; 1527da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15285d0f49c1SAl Viro if (unlikely(!dentry)) { 15295d0f49c1SAl Viro if (unlazy_walk(nd, NULL, 0)) 15305d0f49c1SAl Viro return -ECHILD; 1531e9742b53SAl Viro return 0; 15325d0f49c1SAl Viro } 15335a18fff2SAl Viro 153412f8ad4bSLinus Torvalds /* 153512f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 153612f8ad4bSLinus Torvalds * the dentry name information from lookup. 153712f8ad4bSLinus Torvalds */ 153863afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1539766c4cbfSAl Viro negative = d_is_negative(dentry); 15405d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 154112f8ad4bSLinus Torvalds return -ECHILD; 154212f8ad4bSLinus Torvalds 154312f8ad4bSLinus Torvalds /* 154412f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 154512f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 154612f8ad4bSLinus Torvalds * 154712f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 154812f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 154912f8ad4bSLinus Torvalds */ 15505d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 155131e6b01fSNick Piggin return -ECHILD; 15525a18fff2SAl Viro 1553254cf582SAl Viro *seqp = seq; 15545d0f49c1SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 15554ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15565a18fff2SAl Viro if (unlikely(status <= 0)) { 15575d0f49c1SAl Viro if (unlazy_walk(nd, dentry, seq)) 15585d0f49c1SAl Viro return -ECHILD; 15595d0f49c1SAl Viro if (status == -ECHILD) 15605d0f49c1SAl Viro status = d_revalidate(dentry, nd->flags); 15615d0f49c1SAl Viro } else { 1562daf3761cSTrond Myklebust /* 1563daf3761cSTrond Myklebust * Note: do negative dentry check after revalidation in 1564daf3761cSTrond Myklebust * case that drops it. 1565daf3761cSTrond Myklebust */ 15665d0f49c1SAl Viro if (unlikely(negative)) 1567daf3761cSTrond Myklebust return -ENOENT; 156831e6b01fSNick Piggin path->mnt = mnt; 156931e6b01fSNick Piggin path->dentry = dentry; 1570254cf582SAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 1571e9742b53SAl Viro return 1; 1572254cf582SAl Viro if (unlazy_walk(nd, dentry, seq)) 15735a18fff2SAl Viro return -ECHILD; 15745d0f49c1SAl Viro } 15755a18fff2SAl Viro } else { 1576e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 157781e6f520SAl Viro if (unlikely(!dentry)) 1578e9742b53SAl Viro return 0; 15795d0f49c1SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 15804ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15815d0f49c1SAl Viro } 15825a18fff2SAl Viro if (unlikely(status <= 0)) { 1583e9742b53SAl Viro if (!status) 15845d0f49c1SAl Viro d_invalidate(dentry); 15855a18fff2SAl Viro dput(dentry); 15865a18fff2SAl Viro return status; 15875a18fff2SAl Viro } 1588766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1589766c4cbfSAl Viro dput(dentry); 1590766c4cbfSAl Viro return -ENOENT; 1591766c4cbfSAl Viro } 15925d0f49c1SAl Viro 15931da177e4SLinus Torvalds path->mnt = mnt; 15941da177e4SLinus Torvalds path->dentry = dentry; 1595756daf26SNeilBrown err = follow_managed(path, nd); 1596e9742b53SAl Viro if (likely(err > 0)) 159763afdfc7SDavid Howells *inode = d_backing_inode(path->dentry); 15988402752eSAl Viro return err; 1599697f514dSMiklos Szeredi } 1600697f514dSMiklos Szeredi 1601697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1602e3c13928SAl Viro static struct dentry *lookup_slow(const struct qstr *name, 1603e3c13928SAl Viro struct dentry *dir, 1604e3c13928SAl Viro unsigned int flags) 1605697f514dSMiklos Szeredi { 160694bdd655SAl Viro struct dentry *dentry = ERR_PTR(-ENOENT), *old; 16071936386eSAl Viro struct inode *inode = dir->d_inode; 1608d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 16091936386eSAl Viro 16101936386eSAl Viro inode_lock(inode); 16111936386eSAl Viro /* Don't go there if it's already dead */ 161294bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 161394bdd655SAl Viro goto out; 161494bdd655SAl Viro again: 1615d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 161694bdd655SAl Viro if (IS_ERR(dentry)) 161794bdd655SAl Viro goto out; 161894bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1619949a852eSAl Viro if ((dentry->d_flags & DCACHE_OP_REVALIDATE) && 1620949a852eSAl Viro !(flags & LOOKUP_NO_REVAL)) { 1621949a852eSAl Viro int error = d_revalidate(dentry, flags); 1622949a852eSAl Viro if (unlikely(error <= 0)) { 162394bdd655SAl Viro if (!error) { 1624949a852eSAl Viro d_invalidate(dentry); 1625949a852eSAl Viro dput(dentry); 162694bdd655SAl Viro goto again; 162794bdd655SAl Viro } 162894bdd655SAl Viro dput(dentry); 1629949a852eSAl Viro dentry = ERR_PTR(error); 1630949a852eSAl Viro } 1631949a852eSAl Viro } 163294bdd655SAl Viro } else { 16331936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 163485c7f810SAl Viro d_lookup_done(dentry); 16351936386eSAl Viro if (unlikely(old)) { 16361936386eSAl Viro dput(dentry); 16371936386eSAl Viro dentry = old; 16381936386eSAl Viro } 163994bdd655SAl Viro } 164094bdd655SAl Viro out: 16411936386eSAl Viro inode_unlock(inode); 1642e3c13928SAl Viro return dentry; 16431da177e4SLinus Torvalds } 16441da177e4SLinus Torvalds 164552094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 164652094c8aSAl Viro { 164752094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16484ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 164952094c8aSAl Viro if (err != -ECHILD) 165052094c8aSAl Viro return err; 16516e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 165252094c8aSAl Viro return -ECHILD; 165352094c8aSAl Viro } 16544ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 165552094c8aSAl Viro } 165652094c8aSAl Viro 16579856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 16589856fa1bSAl Viro { 16599856fa1bSAl Viro if (type == LAST_DOTDOT) { 16609e6697e2SAl Viro if (!nd->root.mnt) 16619e6697e2SAl Viro set_root(nd); 16629856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 166370291aecSAl Viro return follow_dotdot_rcu(nd); 16649856fa1bSAl Viro } else 1665397d425dSEric W. Biederman return follow_dotdot(nd); 16669856fa1bSAl Viro } 16679856fa1bSAl Viro return 0; 16689856fa1bSAl Viro } 16699856fa1bSAl Viro 1670181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1671181548c0SAl Viro struct inode *inode, unsigned seq) 1672d63ff28fSAl Viro { 1673626de996SAl Viro int error; 16741cf2665bSAl Viro struct saved *last; 1675756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1676626de996SAl Viro path_to_nameidata(link, nd); 1677626de996SAl Viro return -ELOOP; 1678626de996SAl Viro } 1679bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1680cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1681cd179f44SAl Viro mntget(link->mnt); 16827973387aSAl Viro } 1683626de996SAl Viro error = nd_alloc_stack(nd); 1684626de996SAl Viro if (unlikely(error)) { 1685bc40aee0SAl Viro if (error == -ECHILD) { 1686bc40aee0SAl Viro if (unlikely(unlazy_link(nd, link, seq))) 1687bc40aee0SAl Viro return -ECHILD; 1688bc40aee0SAl Viro error = nd_alloc_stack(nd); 1689bc40aee0SAl Viro } 1690bc40aee0SAl Viro if (error) { 1691cd179f44SAl Viro path_put(link); 1692626de996SAl Viro return error; 1693626de996SAl Viro } 1694bc40aee0SAl Viro } 1695626de996SAl Viro 1696ab104923SAl Viro last = nd->stack + nd->depth++; 16971cf2665bSAl Viro last->link = *link; 1698fceef393SAl Viro clear_delayed_call(&last->done); 1699fceef393SAl Viro nd->link_inode = inode; 17000450b2d1SAl Viro last->seq = seq; 1701d63ff28fSAl Viro return 1; 1702d63ff28fSAl Viro } 1703d63ff28fSAl Viro 17043ddcd056SLinus Torvalds /* 17053ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 17063ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 17073ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 17083ddcd056SLinus Torvalds * for the common case. 17093ddcd056SLinus Torvalds */ 1710254cf582SAl Viro static inline int should_follow_link(struct nameidata *nd, struct path *link, 1711181548c0SAl Viro int follow, 1712181548c0SAl Viro struct inode *inode, unsigned seq) 17133ddcd056SLinus Torvalds { 1714d63ff28fSAl Viro if (likely(!d_is_symlink(link->dentry))) 1715d63ff28fSAl Viro return 0; 1716d63ff28fSAl Viro if (!follow) 1717d63ff28fSAl Viro return 0; 1718a7f77542SAl Viro /* make sure that d_is_symlink above matches inode */ 1719a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 1720a7f77542SAl Viro if (read_seqcount_retry(&link->dentry->d_seq, seq)) 1721a7f77542SAl Viro return -ECHILD; 1722a7f77542SAl Viro } 1723181548c0SAl Viro return pick_link(nd, link, inode, seq); 17243ddcd056SLinus Torvalds } 17253ddcd056SLinus Torvalds 17264693a547SAl Viro enum {WALK_GET = 1, WALK_PUT = 2}; 17274693a547SAl Viro 17284693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1729ce57dfc1SAl Viro { 1730caa85634SAl Viro struct path path; 1731ce57dfc1SAl Viro struct inode *inode; 1732254cf582SAl Viro unsigned seq; 1733ce57dfc1SAl Viro int err; 1734ce57dfc1SAl Viro /* 1735ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1736ce57dfc1SAl Viro * to be able to know about the current root directory and 1737ce57dfc1SAl Viro * parent relationships. 1738ce57dfc1SAl Viro */ 17394693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 17404693a547SAl Viro err = handle_dots(nd, nd->last_type); 17414693a547SAl Viro if (flags & WALK_PUT) 17424693a547SAl Viro put_link(nd); 17434693a547SAl Viro return err; 17444693a547SAl Viro } 1745254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1746e9742b53SAl Viro if (unlikely(err <= 0)) { 1747697f514dSMiklos Szeredi if (err < 0) 1748f0a9ba70SAl Viro return err; 1749e3c13928SAl Viro path.dentry = lookup_slow(&nd->last, nd->path.dentry, 1750e3c13928SAl Viro nd->flags); 1751e3c13928SAl Viro if (IS_ERR(path.dentry)) 1752e3c13928SAl Viro return PTR_ERR(path.dentry); 17537500c38aSAl Viro 1754e3c13928SAl Viro path.mnt = nd->path.mnt; 1755e3c13928SAl Viro err = follow_managed(&path, nd); 1756e3c13928SAl Viro if (unlikely(err < 0)) 1757f0a9ba70SAl Viro return err; 1758697f514dSMiklos Szeredi 17597500c38aSAl Viro if (unlikely(d_is_negative(path.dentry))) { 17607500c38aSAl Viro path_to_nameidata(&path, nd); 17617500c38aSAl Viro return -ENOENT; 17627500c38aSAl Viro } 17637500c38aSAl Viro 1764254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1765d4565649SAl Viro inode = d_backing_inode(path.dentry); 1766766c4cbfSAl Viro } 1767697f514dSMiklos Szeredi 17684693a547SAl Viro if (flags & WALK_PUT) 17694693a547SAl Viro put_link(nd); 1770181548c0SAl Viro err = should_follow_link(nd, &path, flags & WALK_GET, inode, seq); 1771d63ff28fSAl Viro if (unlikely(err)) 1772d63ff28fSAl Viro return err; 1773caa85634SAl Viro path_to_nameidata(&path, nd); 1774ce57dfc1SAl Viro nd->inode = inode; 1775254cf582SAl Viro nd->seq = seq; 1776ce57dfc1SAl Viro return 0; 1777ce57dfc1SAl Viro } 1778ce57dfc1SAl Viro 17791da177e4SLinus Torvalds /* 1780bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1781bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1782bfcfaa77SLinus Torvalds * 1783bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1784bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1785bfcfaa77SLinus Torvalds * fast. 1786bfcfaa77SLinus Torvalds * 1787bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1788bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1789bfcfaa77SLinus Torvalds * crossing operation. 1790bfcfaa77SLinus Torvalds * 1791bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1792bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1793bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1794bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1795bfcfaa77SLinus Torvalds */ 1796bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1797bfcfaa77SLinus Torvalds 1798f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1799bfcfaa77SLinus Torvalds 1800f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1801bfcfaa77SLinus Torvalds 1802bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1803bfcfaa77SLinus Torvalds { 180499d263d4SLinus Torvalds return hash_64(hash, 32); 1805bfcfaa77SLinus Torvalds } 1806bfcfaa77SLinus Torvalds 1807bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1808bfcfaa77SLinus Torvalds 1809bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1810bfcfaa77SLinus Torvalds 1811bfcfaa77SLinus Torvalds #endif 1812bfcfaa77SLinus Torvalds 1813bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1814bfcfaa77SLinus Torvalds { 1815bfcfaa77SLinus Torvalds unsigned long a, mask; 1816bfcfaa77SLinus Torvalds unsigned long hash = 0; 1817bfcfaa77SLinus Torvalds 1818bfcfaa77SLinus Torvalds for (;;) { 1819e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1820bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1821bfcfaa77SLinus Torvalds break; 1822bfcfaa77SLinus Torvalds hash += a; 1823f132c5beSAl Viro hash *= 9; 1824bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1825bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1826bfcfaa77SLinus Torvalds if (!len) 1827bfcfaa77SLinus Torvalds goto done; 1828bfcfaa77SLinus Torvalds } 1829a5c21dceSWill Deacon mask = bytemask_from_count(len); 1830bfcfaa77SLinus Torvalds hash += mask & a; 1831bfcfaa77SLinus Torvalds done: 1832bfcfaa77SLinus Torvalds return fold_hash(hash); 1833bfcfaa77SLinus Torvalds } 1834bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1835bfcfaa77SLinus Torvalds 1836bfcfaa77SLinus Torvalds /* 1837bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1838d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1839bfcfaa77SLinus Torvalds */ 1840d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1841bfcfaa77SLinus Torvalds { 184236126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 184336126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1844bfcfaa77SLinus Torvalds 1845bfcfaa77SLinus Torvalds hash = a = 0; 1846bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1847bfcfaa77SLinus Torvalds do { 1848bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1849bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1850e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 185136126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 185236126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1853bfcfaa77SLinus Torvalds 185436126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 185536126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 185636126f8fSLinus Torvalds 185736126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 185836126f8fSLinus Torvalds 185936126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 18609226b5b4SLinus Torvalds len += find_zero(mask); 1861d6bb3e90SLinus Torvalds return hashlen_create(fold_hash(hash), len); 1862bfcfaa77SLinus Torvalds } 1863bfcfaa77SLinus Torvalds 1864bfcfaa77SLinus Torvalds #else 1865bfcfaa77SLinus Torvalds 18660145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 18670145acc2SLinus Torvalds { 18680145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 18690145acc2SLinus Torvalds while (len--) 18700145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 18710145acc2SLinus Torvalds return end_name_hash(hash); 18720145acc2SLinus Torvalds } 1873ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 18740145acc2SLinus Torvalds 18753ddcd056SLinus Torvalds /* 1876200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1877200e9ef7SLinus Torvalds * one character. 1878200e9ef7SLinus Torvalds */ 1879d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1880200e9ef7SLinus Torvalds { 1881200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1882200e9ef7SLinus Torvalds unsigned long len = 0, c; 1883200e9ef7SLinus Torvalds 1884200e9ef7SLinus Torvalds c = (unsigned char)*name; 1885200e9ef7SLinus Torvalds do { 1886200e9ef7SLinus Torvalds len++; 1887200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1888200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1889200e9ef7SLinus Torvalds } while (c && c != '/'); 1890d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 1891200e9ef7SLinus Torvalds } 1892200e9ef7SLinus Torvalds 1893bfcfaa77SLinus Torvalds #endif 1894bfcfaa77SLinus Torvalds 1895200e9ef7SLinus Torvalds /* 18961da177e4SLinus Torvalds * Name resolution. 1897ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1898ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 18991da177e4SLinus Torvalds * 1900ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1901ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 19021da177e4SLinus Torvalds */ 19036de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 19041da177e4SLinus Torvalds { 19051da177e4SLinus Torvalds int err; 19061da177e4SLinus Torvalds 19071da177e4SLinus Torvalds while (*name=='/') 19081da177e4SLinus Torvalds name++; 19091da177e4SLinus Torvalds if (!*name) 19109e18f10aSAl Viro return 0; 19111da177e4SLinus Torvalds 19121da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 19131da177e4SLinus Torvalds for(;;) { 1914d6bb3e90SLinus Torvalds u64 hash_len; 1915fe479a58SAl Viro int type; 19161da177e4SLinus Torvalds 191752094c8aSAl Viro err = may_lookup(nd); 19181da177e4SLinus Torvalds if (err) 19193595e234SAl Viro return err; 19201da177e4SLinus Torvalds 1921d6bb3e90SLinus Torvalds hash_len = hash_name(name); 19221da177e4SLinus Torvalds 1923fe479a58SAl Viro type = LAST_NORM; 1924d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 1925fe479a58SAl Viro case 2: 1926200e9ef7SLinus Torvalds if (name[1] == '.') { 1927fe479a58SAl Viro type = LAST_DOTDOT; 192816c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 192916c2cd71SAl Viro } 1930fe479a58SAl Viro break; 1931fe479a58SAl Viro case 1: 1932fe479a58SAl Viro type = LAST_DOT; 1933fe479a58SAl Viro } 19345a202bcdSAl Viro if (likely(type == LAST_NORM)) { 19355a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 193616c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 19375a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 1938a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 1939da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 19405a202bcdSAl Viro if (err < 0) 19413595e234SAl Viro return err; 1942d6bb3e90SLinus Torvalds hash_len = this.hash_len; 1943d6bb3e90SLinus Torvalds name = this.name; 19445a202bcdSAl Viro } 19455a202bcdSAl Viro } 1946fe479a58SAl Viro 1947d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 1948d6bb3e90SLinus Torvalds nd->last.name = name; 19495f4a6a69SAl Viro nd->last_type = type; 19505f4a6a69SAl Viro 1951d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 1952d6bb3e90SLinus Torvalds if (!*name) 1953bdf6cbf1SAl Viro goto OK; 1954200e9ef7SLinus Torvalds /* 1955200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1956200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1957200e9ef7SLinus Torvalds */ 1958200e9ef7SLinus Torvalds do { 1959d6bb3e90SLinus Torvalds name++; 1960d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 19618620c238SAl Viro if (unlikely(!*name)) { 19628620c238SAl Viro OK: 1963368ee9baSAl Viro /* pathname body, done */ 19648620c238SAl Viro if (!nd->depth) 19658620c238SAl Viro return 0; 19668620c238SAl Viro name = nd->stack[nd->depth - 1].name; 1967368ee9baSAl Viro /* trailing symlink, done */ 19688620c238SAl Viro if (!name) 19698620c238SAl Viro return 0; 19708620c238SAl Viro /* last component of nested symlink */ 19714693a547SAl Viro err = walk_component(nd, WALK_GET | WALK_PUT); 19728620c238SAl Viro } else { 19734693a547SAl Viro err = walk_component(nd, WALK_GET); 19748620c238SAl Viro } 1975ce57dfc1SAl Viro if (err < 0) 19763595e234SAl Viro return err; 1977fe479a58SAl Viro 1978ce57dfc1SAl Viro if (err) { 1979626de996SAl Viro const char *s = get_link(nd); 19805a460275SAl Viro 1981a1c83681SViresh Kumar if (IS_ERR(s)) 19823595e234SAl Viro return PTR_ERR(s); 1983172a39a0SAl Viro err = 0; 198412b09578SAl Viro if (unlikely(!s)) { 198512b09578SAl Viro /* jumped */ 1986b9ff4429SAl Viro put_link(nd); 198712b09578SAl Viro } else { 1988071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 198932cd7468SAl Viro name = s; 19909e18f10aSAl Viro continue; 199148c8b0c5SAl Viro } 199231e6b01fSNick Piggin } 199397242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 199497242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 199597242f99SAl Viro if (unlazy_walk(nd, NULL, 0)) 199697242f99SAl Viro return -ECHILD; 199797242f99SAl Viro } 19983595e234SAl Viro return -ENOTDIR; 19995f4a6a69SAl Viro } 2000ce57dfc1SAl Viro } 200197242f99SAl Viro } 20021da177e4SLinus Torvalds 2003c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 200431e6b01fSNick Piggin { 200531e6b01fSNick Piggin int retval = 0; 2006c8a53ee5SAl Viro const char *s = nd->name->name; 200731e6b01fSNick Piggin 200831e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 2009980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 201031e6b01fSNick Piggin nd->depth = 0; 20115b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2012b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2013b18825a7SDavid Howells struct inode *inode = root->d_inode; 2014fd2f7cb5SAl Viro if (*s) { 201544b1d530SMiklos Szeredi if (!d_can_lookup(root)) 2016368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 20175b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 20185b6ca027SAl Viro if (retval) 2019368ee9baSAl Viro return ERR_PTR(retval); 202073d049a4SAl Viro } 20215b6ca027SAl Viro nd->path = nd->root; 20225b6ca027SAl Viro nd->inode = inode; 20235b6ca027SAl Viro if (flags & LOOKUP_RCU) { 20248b61e74fSAl Viro rcu_read_lock(); 20255b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 20268f47a016SAl Viro nd->root_seq = nd->seq; 202748a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 20285b6ca027SAl Viro } else { 20295b6ca027SAl Viro path_get(&nd->path); 20305b6ca027SAl Viro } 2031368ee9baSAl Viro return s; 20325b6ca027SAl Viro } 20335b6ca027SAl Viro 203431e6b01fSNick Piggin nd->root.mnt = NULL; 2035248fb5b9SAl Viro nd->path.mnt = NULL; 2036248fb5b9SAl Viro nd->path.dentry = NULL; 203731e6b01fSNick Piggin 203848a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 2039fd2f7cb5SAl Viro if (*s == '/') { 20409e6697e2SAl Viro if (flags & LOOKUP_RCU) 20418b61e74fSAl Viro rcu_read_lock(); 2042e41f7d4eSAl Viro set_root(nd); 2043248fb5b9SAl Viro if (likely(!nd_jump_root(nd))) 2044ef55d917SAl Viro return s; 2045ef55d917SAl Viro nd->root.mnt = NULL; 2046ef55d917SAl Viro rcu_read_unlock(); 2047ef55d917SAl Viro return ERR_PTR(-ECHILD); 2048c8a53ee5SAl Viro } else if (nd->dfd == AT_FDCWD) { 2049e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 205031e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2051c28cc364SNick Piggin unsigned seq; 205231e6b01fSNick Piggin 20538b61e74fSAl Viro rcu_read_lock(); 205431e6b01fSNick Piggin 2055c28cc364SNick Piggin do { 2056c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 205731e6b01fSNick Piggin nd->path = fs->pwd; 2058ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2059c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2060c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2061e41f7d4eSAl Viro } else { 2062e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2063ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2064e41f7d4eSAl Viro } 2065ef55d917SAl Viro return s; 206631e6b01fSNick Piggin } else { 2067582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2068c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 206931e6b01fSNick Piggin struct dentry *dentry; 207031e6b01fSNick Piggin 20712903ff01SAl Viro if (!f.file) 2072368ee9baSAl Viro return ERR_PTR(-EBADF); 207331e6b01fSNick Piggin 20742903ff01SAl Viro dentry = f.file->f_path.dentry; 207531e6b01fSNick Piggin 2076fd2f7cb5SAl Viro if (*s) { 207744b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 20782903ff01SAl Viro fdput(f); 2079368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2080f52e0c11SAl Viro } 20812903ff01SAl Viro } 20822903ff01SAl Viro 20832903ff01SAl Viro nd->path = f.file->f_path; 2084e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 20858b61e74fSAl Viro rcu_read_lock(); 208634a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 208734a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 20885590ff0dSUlrich Drepper } else { 20892903ff01SAl Viro path_get(&nd->path); 209034a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 20911da177e4SLinus Torvalds } 209234a26b99SAl Viro fdput(f); 2093368ee9baSAl Viro return s; 2094e41f7d4eSAl Viro } 20959b4a9b14SAl Viro } 20969b4a9b14SAl Viro 20973bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 209895fa25d9SAl Viro { 209995fa25d9SAl Viro const char *s; 2100fec2fa24SAl Viro int error = may_follow_link(nd); 2101deb106c6SAl Viro if (unlikely(error)) 21023bdba28bSAl Viro return ERR_PTR(error); 210395fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2104fab51e8aSAl Viro nd->stack[0].name = NULL; 21053b2e7f75SAl Viro s = get_link(nd); 2106deb106c6SAl Viro return s ? s : ""; 210795fa25d9SAl Viro } 210895fa25d9SAl Viro 2109caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2110bd92d7feSAl Viro { 2111bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2112bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2113bd92d7feSAl Viro 2114bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 2115deb106c6SAl Viro return walk_component(nd, 21164693a547SAl Viro nd->flags & LOOKUP_FOLLOW 21174693a547SAl Viro ? nd->depth 21184693a547SAl Viro ? WALK_PUT | WALK_GET 21194693a547SAl Viro : WALK_GET 21204693a547SAl Viro : 0); 2121bd92d7feSAl Viro } 2122bd92d7feSAl Viro 21239b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2124c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 21259b4a9b14SAl Viro { 2126c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2127bd92d7feSAl Viro int err; 212831e6b01fSNick Piggin 2129368ee9baSAl Viro if (IS_ERR(s)) 2130368ee9baSAl Viro return PTR_ERR(s); 21313bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 21323bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 21333bdba28bSAl Viro s = trailing_symlink(nd); 21343bdba28bSAl Viro if (IS_ERR(s)) { 21353bdba28bSAl Viro err = PTR_ERR(s); 21366d7b5aaeSAl Viro break; 2137bd92d7feSAl Viro } 2138bd92d7feSAl Viro } 21399f1fafeeSAl Viro if (!err) 21409f1fafeeSAl Viro err = complete_walk(nd); 2141bd92d7feSAl Viro 2142deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2143deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2144bd23a539SAl Viro err = -ENOTDIR; 2145625b6d10SAl Viro if (!err) { 2146625b6d10SAl Viro *path = nd->path; 2147625b6d10SAl Viro nd->path.mnt = NULL; 2148625b6d10SAl Viro nd->path.dentry = NULL; 2149625b6d10SAl Viro } 2150deb106c6SAl Viro terminate_walk(nd); 2151bd92d7feSAl Viro return err; 215231e6b01fSNick Piggin } 215331e6b01fSNick Piggin 2154625b6d10SAl Viro static int filename_lookup(int dfd, struct filename *name, unsigned flags, 21559ad1aaa6SAl Viro struct path *path, struct path *root) 2156873f1eedSJeff Layton { 2157894bc8c4SAl Viro int retval; 21589883d185SAl Viro struct nameidata nd; 2159abc9f5beSAl Viro if (IS_ERR(name)) 2160abc9f5beSAl Viro return PTR_ERR(name); 21619ad1aaa6SAl Viro if (unlikely(root)) { 21629ad1aaa6SAl Viro nd.root = *root; 21639ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 21649ad1aaa6SAl Viro } 21659883d185SAl Viro set_nameidata(&nd, dfd, name); 2166c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2167873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2168c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2169873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2170c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2171873f1eedSJeff Layton 2172873f1eedSJeff Layton if (likely(!retval)) 2173625b6d10SAl Viro audit_inode(name, path->dentry, flags & LOOKUP_PARENT); 21749883d185SAl Viro restore_nameidata(); 2175e4bd1c1aSAl Viro putname(name); 2176873f1eedSJeff Layton return retval; 2177873f1eedSJeff Layton } 2178873f1eedSJeff Layton 21798bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2180c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2181391172c4SAl Viro struct path *parent) 21828bcb77faSAl Viro { 2183c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2184368ee9baSAl Viro int err; 2185368ee9baSAl Viro if (IS_ERR(s)) 2186368ee9baSAl Viro return PTR_ERR(s); 2187368ee9baSAl Viro err = link_path_walk(s, nd); 21888bcb77faSAl Viro if (!err) 21898bcb77faSAl Viro err = complete_walk(nd); 2190391172c4SAl Viro if (!err) { 2191391172c4SAl Viro *parent = nd->path; 2192391172c4SAl Viro nd->path.mnt = NULL; 2193391172c4SAl Viro nd->path.dentry = NULL; 2194391172c4SAl Viro } 2195deb106c6SAl Viro terminate_walk(nd); 21968bcb77faSAl Viro return err; 21978bcb77faSAl Viro } 21988bcb77faSAl Viro 21995c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2200391172c4SAl Viro unsigned int flags, struct path *parent, 2201391172c4SAl Viro struct qstr *last, int *type) 22028bcb77faSAl Viro { 22038bcb77faSAl Viro int retval; 22049883d185SAl Viro struct nameidata nd; 22058bcb77faSAl Viro 22065c31b6ceSAl Viro if (IS_ERR(name)) 22075c31b6ceSAl Viro return name; 22089883d185SAl Viro set_nameidata(&nd, dfd, name); 2209c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 22108bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2211c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 22128bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2213c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2214391172c4SAl Viro if (likely(!retval)) { 2215391172c4SAl Viro *last = nd.last; 2216391172c4SAl Viro *type = nd.last_type; 2217391172c4SAl Viro audit_inode(name, parent->dentry, LOOKUP_PARENT); 22185c31b6ceSAl Viro } else { 22195c31b6ceSAl Viro putname(name); 22205c31b6ceSAl Viro name = ERR_PTR(retval); 2221391172c4SAl Viro } 22229883d185SAl Viro restore_nameidata(); 22235c31b6ceSAl Viro return name; 22248bcb77faSAl Viro } 22258bcb77faSAl Viro 222679714f72SAl Viro /* does lookup, returns the object with parent locked */ 222779714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 22285590ff0dSUlrich Drepper { 22295c31b6ceSAl Viro struct filename *filename; 22305c31b6ceSAl Viro struct dentry *d; 2231391172c4SAl Viro struct qstr last; 2232391172c4SAl Viro int type; 223351689104SPaul Moore 22345c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 22355c31b6ceSAl Viro &last, &type); 223651689104SPaul Moore if (IS_ERR(filename)) 223751689104SPaul Moore return ERR_CAST(filename); 22385c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2239391172c4SAl Viro path_put(path); 22405c31b6ceSAl Viro putname(filename); 22415c31b6ceSAl Viro return ERR_PTR(-EINVAL); 224279714f72SAl Viro } 22435955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2244391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 224579714f72SAl Viro if (IS_ERR(d)) { 22465955102cSAl Viro inode_unlock(path->dentry->d_inode); 2247391172c4SAl Viro path_put(path); 224879714f72SAl Viro } 224951689104SPaul Moore putname(filename); 225079714f72SAl Viro return d; 22515590ff0dSUlrich Drepper } 22525590ff0dSUlrich Drepper 2253d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2254d1811465SAl Viro { 2255abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2256abc9f5beSAl Viro flags, path, NULL); 2257d1811465SAl Viro } 22584d359507SAl Viro EXPORT_SYMBOL(kern_path); 2259d1811465SAl Viro 226016f18200SJosef 'Jeff' Sipek /** 226116f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 226216f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 226316f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 226416f18200SJosef 'Jeff' Sipek * @name: pointer to file name 226516f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2266e0a01249SAl Viro * @path: pointer to struct path to fill 226716f18200SJosef 'Jeff' Sipek */ 226816f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 226916f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2270e0a01249SAl Viro struct path *path) 227116f18200SJosef 'Jeff' Sipek { 22729ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 22739ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2274abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2275abc9f5beSAl Viro flags , path, &root); 227616f18200SJosef 'Jeff' Sipek } 22774d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 227816f18200SJosef 'Jeff' Sipek 2279eead1911SChristoph Hellwig /** 2280a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2281eead1911SChristoph Hellwig * @name: pathname component to lookup 2282eead1911SChristoph Hellwig * @base: base directory to lookup from 2283eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2284eead1911SChristoph Hellwig * 2285a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 22869e7543e9SAl Viro * not be called by generic code. 2287bbddca8eSNeilBrown * 2288bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2289eead1911SChristoph Hellwig */ 2290057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2291057f6c01SJames Morris { 2292057f6c01SJames Morris struct qstr this; 22936a96ba54SAl Viro unsigned int c; 2294cda309deSMiklos Szeredi int err; 2295057f6c01SJames Morris 22965955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 22972f9092e1SDavid Woodhouse 22986a96ba54SAl Viro this.name = name; 22996a96ba54SAl Viro this.len = len; 23000145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 23016a96ba54SAl Viro if (!len) 23026a96ba54SAl Viro return ERR_PTR(-EACCES); 23036a96ba54SAl Viro 230421d8a15aSAl Viro if (unlikely(name[0] == '.')) { 230521d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 230621d8a15aSAl Viro return ERR_PTR(-EACCES); 230721d8a15aSAl Viro } 230821d8a15aSAl Viro 23096a96ba54SAl Viro while (len--) { 23106a96ba54SAl Viro c = *(const unsigned char *)name++; 23116a96ba54SAl Viro if (c == '/' || c == '\0') 23126a96ba54SAl Viro return ERR_PTR(-EACCES); 23136a96ba54SAl Viro } 23145a202bcdSAl Viro /* 23155a202bcdSAl Viro * See if the low-level filesystem might want 23165a202bcdSAl Viro * to use its own hash.. 23175a202bcdSAl Viro */ 23185a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2319da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 23205a202bcdSAl Viro if (err < 0) 23215a202bcdSAl Viro return ERR_PTR(err); 23225a202bcdSAl Viro } 2323eead1911SChristoph Hellwig 2324cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2325cda309deSMiklos Szeredi if (err) 2326cda309deSMiklos Szeredi return ERR_PTR(err); 2327cda309deSMiklos Szeredi 232872bd866aSAl Viro return __lookup_hash(&this, base, 0); 2329057f6c01SJames Morris } 23304d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2331057f6c01SJames Morris 2332bbddca8eSNeilBrown /** 2333bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2334bbddca8eSNeilBrown * @name: pathname component to lookup 2335bbddca8eSNeilBrown * @base: base directory to lookup from 2336bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2337bbddca8eSNeilBrown * 2338bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2339bbddca8eSNeilBrown * not be called by generic code. 2340bbddca8eSNeilBrown * 2341bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2342bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2343bbddca8eSNeilBrown */ 2344bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2345bbddca8eSNeilBrown struct dentry *base, int len) 2346bbddca8eSNeilBrown { 2347bbddca8eSNeilBrown struct qstr this; 2348bbddca8eSNeilBrown unsigned int c; 2349bbddca8eSNeilBrown int err; 2350bbddca8eSNeilBrown struct dentry *ret; 2351bbddca8eSNeilBrown 2352bbddca8eSNeilBrown this.name = name; 2353bbddca8eSNeilBrown this.len = len; 2354bbddca8eSNeilBrown this.hash = full_name_hash(name, len); 2355bbddca8eSNeilBrown if (!len) 2356bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2357bbddca8eSNeilBrown 2358bbddca8eSNeilBrown if (unlikely(name[0] == '.')) { 2359bbddca8eSNeilBrown if (len < 2 || (len == 2 && name[1] == '.')) 2360bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2361bbddca8eSNeilBrown } 2362bbddca8eSNeilBrown 2363bbddca8eSNeilBrown while (len--) { 2364bbddca8eSNeilBrown c = *(const unsigned char *)name++; 2365bbddca8eSNeilBrown if (c == '/' || c == '\0') 2366bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2367bbddca8eSNeilBrown } 2368bbddca8eSNeilBrown /* 2369bbddca8eSNeilBrown * See if the low-level filesystem might want 2370bbddca8eSNeilBrown * to use its own hash.. 2371bbddca8eSNeilBrown */ 2372bbddca8eSNeilBrown if (base->d_flags & DCACHE_OP_HASH) { 2373bbddca8eSNeilBrown int err = base->d_op->d_hash(base, &this); 2374bbddca8eSNeilBrown if (err < 0) 2375bbddca8eSNeilBrown return ERR_PTR(err); 2376bbddca8eSNeilBrown } 2377bbddca8eSNeilBrown 2378bbddca8eSNeilBrown err = inode_permission(base->d_inode, MAY_EXEC); 2379bbddca8eSNeilBrown if (err) 2380bbddca8eSNeilBrown return ERR_PTR(err); 2381bbddca8eSNeilBrown 2382d6d95dedSAl Viro ret = lookup_dcache(&this, base, 0); 2383e3c13928SAl Viro if (!ret) 2384e3c13928SAl Viro ret = lookup_slow(&this, base, 0); 2385bbddca8eSNeilBrown return ret; 2386bbddca8eSNeilBrown } 2387bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2388bbddca8eSNeilBrown 23891fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 23901fa1e7f6SAndy Whitcroft struct path *path, int *empty) 23911da177e4SLinus Torvalds { 2392abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2393abc9f5beSAl Viro flags, path, NULL); 23941da177e4SLinus Torvalds } 2395b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 23961fa1e7f6SAndy Whitcroft 2397873f1eedSJeff Layton /* 2398873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2399873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2400873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2401873f1eedSJeff Layton * path-walking is complete. 2402873f1eedSJeff Layton */ 2403a2ec4a2dSAl Viro static inline struct filename * 2404f5beed75SAl Viro user_path_parent(int dfd, const char __user *path, 2405f5beed75SAl Viro struct path *parent, 2406f5beed75SAl Viro struct qstr *last, 2407f5beed75SAl Viro int *type, 24089e790bd6SJeff Layton unsigned int flags) 24092ad94ae6SAl Viro { 24109e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 24115c31b6ceSAl Viro return filename_parentat(dfd, getname(path), flags & LOOKUP_REVAL, 24125c31b6ceSAl Viro parent, last, type); 24132ad94ae6SAl Viro } 24142ad94ae6SAl Viro 24158033426eSJeff Layton /** 2416197df04cSAl Viro * mountpoint_last - look up last component for umount 24178033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 24188033426eSJeff Layton * @path: pointer to container for result 24198033426eSJeff Layton * 24208033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 24218033426eSJeff Layton * need to resolve the path without doing any revalidation. 24228033426eSJeff Layton * 24238033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 24248033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 24258033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 24268033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 24278033426eSJeff Layton * bogus and it doesn't exist. 24288033426eSJeff Layton * 24298033426eSJeff Layton * Returns: 24308033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 24318033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 24328033426eSJeff Layton * put in this case. 24338033426eSJeff Layton * 24348033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 24358033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 24368033426eSJeff Layton * The nd->path reference will also be put. 24378033426eSJeff Layton * 24388033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 24398033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 24408033426eSJeff Layton * to the link, and nd->path will *not* be put. 24418033426eSJeff Layton */ 24428033426eSJeff Layton static int 2443197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 24448033426eSJeff Layton { 24458033426eSJeff Layton int error = 0; 24468033426eSJeff Layton struct dentry *dentry; 24478033426eSJeff Layton struct dentry *dir = nd->path.dentry; 24488033426eSJeff Layton 244935759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 245035759521SAl Viro if (nd->flags & LOOKUP_RCU) { 24516e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 2452deb106c6SAl Viro return -ECHILD; 24538033426eSJeff Layton } 24548033426eSJeff Layton 24558033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 24568033426eSJeff Layton 24578033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 24588033426eSJeff Layton error = handle_dots(nd, nd->last_type); 245935759521SAl Viro if (error) 2460deb106c6SAl Viro return error; 24618033426eSJeff Layton dentry = dget(nd->path.dentry); 2462949a852eSAl Viro } else { 24638033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 24648033426eSJeff Layton if (!dentry) { 24658033426eSJeff Layton /* 2466949a852eSAl Viro * No cached dentry. Mounted dentries are pinned in the 2467949a852eSAl Viro * cache, so that means that this dentry is probably 2468949a852eSAl Viro * a symlink or the path doesn't actually point 2469949a852eSAl Viro * to a mounted dentry. 24708033426eSJeff Layton */ 2471949a852eSAl Viro dentry = lookup_slow(&nd->last, dir, 2472949a852eSAl Viro nd->flags | LOOKUP_NO_REVAL); 2473949a852eSAl Viro if (IS_ERR(dentry)) 2474deb106c6SAl Viro return PTR_ERR(dentry); 24758033426eSJeff Layton } 2476bcceeebaSDave Jones } 2477698934dfSDavid Howells if (d_is_negative(dentry)) { 24788033426eSJeff Layton dput(dentry); 2479deb106c6SAl Viro return -ENOENT; 248035759521SAl Viro } 2481191d7f73SAl Viro if (nd->depth) 2482191d7f73SAl Viro put_link(nd); 24838033426eSJeff Layton path->dentry = dentry; 2484295dc39dSVasily Averin path->mnt = nd->path.mnt; 2485181548c0SAl Viro error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW, 2486181548c0SAl Viro d_backing_inode(dentry), 0); 2487deb106c6SAl Viro if (unlikely(error)) 2488d63ff28fSAl Viro return error; 2489295dc39dSVasily Averin mntget(path->mnt); 24908033426eSJeff Layton follow_mount(path); 2491deb106c6SAl Viro return 0; 24928033426eSJeff Layton } 24938033426eSJeff Layton 24948033426eSJeff Layton /** 2495197df04cSAl Viro * path_mountpoint - look up a path to be umounted 24962a78b857SMasanari Iida * @nd: lookup context 24978033426eSJeff Layton * @flags: lookup flags 2498c8a53ee5SAl Viro * @path: pointer to container for result 24998033426eSJeff Layton * 25008033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2501606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 25028033426eSJeff Layton */ 25038033426eSJeff Layton static int 2504c8a53ee5SAl Viro path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) 25058033426eSJeff Layton { 2506c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2507368ee9baSAl Viro int err; 2508368ee9baSAl Viro if (IS_ERR(s)) 2509368ee9baSAl Viro return PTR_ERR(s); 25103bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 25113bdba28bSAl Viro (err = mountpoint_last(nd, path)) > 0) { 25123bdba28bSAl Viro s = trailing_symlink(nd); 25133bdba28bSAl Viro if (IS_ERR(s)) { 25143bdba28bSAl Viro err = PTR_ERR(s); 25158033426eSJeff Layton break; 25168033426eSJeff Layton } 25173bdba28bSAl Viro } 2518deb106c6SAl Viro terminate_walk(nd); 25198033426eSJeff Layton return err; 25208033426eSJeff Layton } 25218033426eSJeff Layton 25222d864651SAl Viro static int 2523668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 25242d864651SAl Viro unsigned int flags) 25252d864651SAl Viro { 25269883d185SAl Viro struct nameidata nd; 2527cbaab2dbSAl Viro int error; 2528668696dcSAl Viro if (IS_ERR(name)) 2529668696dcSAl Viro return PTR_ERR(name); 25309883d185SAl Viro set_nameidata(&nd, dfd, name); 2531c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); 25322d864651SAl Viro if (unlikely(error == -ECHILD)) 2533c8a53ee5SAl Viro error = path_mountpoint(&nd, flags, path); 25342d864651SAl Viro if (unlikely(error == -ESTALE)) 2535c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); 25362d864651SAl Viro if (likely(!error)) 2537668696dcSAl Viro audit_inode(name, path->dentry, 0); 25389883d185SAl Viro restore_nameidata(); 2539668696dcSAl Viro putname(name); 25402d864651SAl Viro return error; 25412d864651SAl Viro } 25422d864651SAl Viro 25438033426eSJeff Layton /** 2544197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 25458033426eSJeff Layton * @dfd: directory file descriptor 25468033426eSJeff Layton * @name: pathname from userland 25478033426eSJeff Layton * @flags: lookup flags 25488033426eSJeff Layton * @path: pointer to container to hold result 25498033426eSJeff Layton * 25508033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 25518033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 25528033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 25538033426eSJeff Layton * and avoid revalidating the last component. 25548033426eSJeff Layton * 25558033426eSJeff Layton * Returns 0 and populates "path" on success. 25568033426eSJeff Layton */ 25578033426eSJeff Layton int 2558197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 25598033426eSJeff Layton struct path *path) 25608033426eSJeff Layton { 2561cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 25628033426eSJeff Layton } 25638033426eSJeff Layton 25642d864651SAl Viro int 25652d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 25662d864651SAl Viro unsigned int flags) 25672d864651SAl Viro { 2568cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 25692d864651SAl Viro } 25702d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 25712d864651SAl Viro 2572cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 25731da177e4SLinus Torvalds { 25748e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2575da9592edSDavid Howells 25768e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 25771da177e4SLinus Torvalds return 0; 25788e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 25791da177e4SLinus Torvalds return 0; 258023adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 25811da177e4SLinus Torvalds } 2582cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 25831da177e4SLinus Torvalds 25841da177e4SLinus Torvalds /* 25851da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 25861da177e4SLinus Torvalds * whether the type of victim is right. 25871da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 25881da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 25891da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 25901da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 25911da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 25921da177e4SLinus Torvalds * a. be owner of dir, or 25931da177e4SLinus Torvalds * b. be owner of victim, or 25941da177e4SLinus Torvalds * c. have CAP_FOWNER capability 25951da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 25961da177e4SLinus Torvalds * links pointing to it. 25971da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 25981da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 25991da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 26001da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 26011da177e4SLinus Torvalds * nfs_async_unlink(). 26021da177e4SLinus Torvalds */ 2603b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 26041da177e4SLinus Torvalds { 260563afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 26061da177e4SLinus Torvalds int error; 26071da177e4SLinus Torvalds 2608b18825a7SDavid Howells if (d_is_negative(victim)) 26091da177e4SLinus Torvalds return -ENOENT; 2610b18825a7SDavid Howells BUG_ON(!inode); 26111da177e4SLinus Torvalds 26121da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 26134fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 26141da177e4SLinus Torvalds 2615f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 26161da177e4SLinus Torvalds if (error) 26171da177e4SLinus Torvalds return error; 26181da177e4SLinus Torvalds if (IS_APPEND(dir)) 26191da177e4SLinus Torvalds return -EPERM; 2620b18825a7SDavid Howells 2621b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2622b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 26231da177e4SLinus Torvalds return -EPERM; 26241da177e4SLinus Torvalds if (isdir) { 262544b1d530SMiklos Szeredi if (!d_is_dir(victim)) 26261da177e4SLinus Torvalds return -ENOTDIR; 26271da177e4SLinus Torvalds if (IS_ROOT(victim)) 26281da177e4SLinus Torvalds return -EBUSY; 262944b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 26301da177e4SLinus Torvalds return -EISDIR; 26311da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 26321da177e4SLinus Torvalds return -ENOENT; 26331da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 26341da177e4SLinus Torvalds return -EBUSY; 26351da177e4SLinus Torvalds return 0; 26361da177e4SLinus Torvalds } 26371da177e4SLinus Torvalds 26381da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 26391da177e4SLinus Torvalds * dir. 26401da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 26411da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 26421da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 26431da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 26441da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 26451da177e4SLinus Torvalds */ 2646a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 26471da177e4SLinus Torvalds { 264814e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 26491da177e4SLinus Torvalds if (child->d_inode) 26501da177e4SLinus Torvalds return -EEXIST; 26511da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 26521da177e4SLinus Torvalds return -ENOENT; 2653f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 26541da177e4SLinus Torvalds } 26551da177e4SLinus Torvalds 26561da177e4SLinus Torvalds /* 26571da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 26581da177e4SLinus Torvalds */ 26591da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 26601da177e4SLinus Torvalds { 26611da177e4SLinus Torvalds struct dentry *p; 26621da177e4SLinus Torvalds 26631da177e4SLinus Torvalds if (p1 == p2) { 26645955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 26651da177e4SLinus Torvalds return NULL; 26661da177e4SLinus Torvalds } 26671da177e4SLinus Torvalds 2668fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 26691da177e4SLinus Torvalds 2670e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2671e2761a11SOGAWA Hirofumi if (p) { 26725955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 26735955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 26741da177e4SLinus Torvalds return p; 26751da177e4SLinus Torvalds } 26761da177e4SLinus Torvalds 2677e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2678e2761a11SOGAWA Hirofumi if (p) { 26795955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 26805955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 26811da177e4SLinus Torvalds return p; 26821da177e4SLinus Torvalds } 26831da177e4SLinus Torvalds 26845955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 26855955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 26861da177e4SLinus Torvalds return NULL; 26871da177e4SLinus Torvalds } 26884d359507SAl Viro EXPORT_SYMBOL(lock_rename); 26891da177e4SLinus Torvalds 26901da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 26911da177e4SLinus Torvalds { 26925955102cSAl Viro inode_unlock(p1->d_inode); 26931da177e4SLinus Torvalds if (p1 != p2) { 26945955102cSAl Viro inode_unlock(p2->d_inode); 2695fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 26961da177e4SLinus Torvalds } 26971da177e4SLinus Torvalds } 26984d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 26991da177e4SLinus Torvalds 27004acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2701312b63fbSAl Viro bool want_excl) 27021da177e4SLinus Torvalds { 2703a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 27041da177e4SLinus Torvalds if (error) 27051da177e4SLinus Torvalds return error; 27061da177e4SLinus Torvalds 2707acfa4380SAl Viro if (!dir->i_op->create) 27081da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 27091da177e4SLinus Torvalds mode &= S_IALLUGO; 27101da177e4SLinus Torvalds mode |= S_IFREG; 27111da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 27121da177e4SLinus Torvalds if (error) 27131da177e4SLinus Torvalds return error; 2714312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2715a74574aaSStephen Smalley if (!error) 2716f38aa942SAmy Griffis fsnotify_create(dir, dentry); 27171da177e4SLinus Torvalds return error; 27181da177e4SLinus Torvalds } 27194d359507SAl Viro EXPORT_SYMBOL(vfs_create); 27201da177e4SLinus Torvalds 272173d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 27221da177e4SLinus Torvalds { 27233fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 27241da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 27251da177e4SLinus Torvalds int error; 27261da177e4SLinus Torvalds 27271da177e4SLinus Torvalds if (!inode) 27281da177e4SLinus Torvalds return -ENOENT; 27291da177e4SLinus Torvalds 2730c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2731c8fe8f30SChristoph Hellwig case S_IFLNK: 27321da177e4SLinus Torvalds return -ELOOP; 2733c8fe8f30SChristoph Hellwig case S_IFDIR: 2734c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 27351da177e4SLinus Torvalds return -EISDIR; 2736c8fe8f30SChristoph Hellwig break; 2737c8fe8f30SChristoph Hellwig case S_IFBLK: 2738c8fe8f30SChristoph Hellwig case S_IFCHR: 27393fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 27401da177e4SLinus Torvalds return -EACCES; 2741c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2742c8fe8f30SChristoph Hellwig case S_IFIFO: 2743c8fe8f30SChristoph Hellwig case S_IFSOCK: 27441da177e4SLinus Torvalds flag &= ~O_TRUNC; 2745c8fe8f30SChristoph Hellwig break; 27464a3fd211SDave Hansen } 2747b41572e9SDave Hansen 274862fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2749b41572e9SDave Hansen if (error) 2750b41572e9SDave Hansen return error; 27516146f0d5SMimi Zohar 27521da177e4SLinus Torvalds /* 27531da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 27541da177e4SLinus Torvalds */ 27551da177e4SLinus Torvalds if (IS_APPEND(inode)) { 27568737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 27577715b521SAl Viro return -EPERM; 27581da177e4SLinus Torvalds if (flag & O_TRUNC) 27597715b521SAl Viro return -EPERM; 27601da177e4SLinus Torvalds } 27611da177e4SLinus Torvalds 27621da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 27632e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 27647715b521SAl Viro return -EPERM; 27651da177e4SLinus Torvalds 2766f3c7691eSJ. Bruce Fields return 0; 27677715b521SAl Viro } 27687715b521SAl Viro 2769e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 27707715b521SAl Viro { 2771e1181ee6SJeff Layton struct path *path = &filp->f_path; 27727715b521SAl Viro struct inode *inode = path->dentry->d_inode; 27737715b521SAl Viro int error = get_write_access(inode); 27741da177e4SLinus Torvalds if (error) 27757715b521SAl Viro return error; 27761da177e4SLinus Torvalds /* 27771da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 27781da177e4SLinus Torvalds */ 2779d7a06983SJeff Layton error = locks_verify_locked(filp); 2780be6d3e56SKentaro Takeda if (!error) 2781ea0d3ab2STetsuo Handa error = security_path_truncate(path); 27821da177e4SLinus Torvalds if (!error) { 27837715b521SAl Viro error = do_truncate(path->dentry, 0, 2784d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2785e1181ee6SJeff Layton filp); 27861da177e4SLinus Torvalds } 27871da177e4SLinus Torvalds put_write_access(inode); 2788acd0c935SMimi Zohar return error; 27891da177e4SLinus Torvalds } 27901da177e4SLinus Torvalds 2791d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2792d57999e1SDave Hansen { 27938a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 27948a5e929dSAl Viro flag--; 2795d57999e1SDave Hansen return flag; 2796d57999e1SDave Hansen } 2797d57999e1SDave Hansen 2798d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2799d18e9008SMiklos Szeredi { 2800d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2801d18e9008SMiklos Szeredi if (error) 2802d18e9008SMiklos Szeredi return error; 2803d18e9008SMiklos Szeredi 2804d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2805d18e9008SMiklos Szeredi if (error) 2806d18e9008SMiklos Szeredi return error; 2807d18e9008SMiklos Szeredi 2808d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2809d18e9008SMiklos Szeredi } 2810d18e9008SMiklos Szeredi 28111acf0af9SDavid Howells /* 28121acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 28131acf0af9SDavid Howells * dentry. 28141acf0af9SDavid Howells * 28151acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 28161acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 28171acf0af9SDavid Howells * 28181acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 28191acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 28201acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 28211acf0af9SDavid Howells * 28221acf0af9SDavid Howells * Returns an error code otherwise. 28231acf0af9SDavid Howells */ 28242675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 282530d90494SAl Viro struct path *path, struct file *file, 2826015c3bbcSMiklos Szeredi const struct open_flags *op, 282764894cf8SAl Viro bool got_write, bool need_lookup, 282847237687SAl Viro int *opened) 2829d18e9008SMiklos Szeredi { 2830d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2831d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2832d18e9008SMiklos Szeredi umode_t mode; 2833d18e9008SMiklos Szeredi int error; 2834d18e9008SMiklos Szeredi int acc_mode; 2835d18e9008SMiklos Szeredi int create_error = 0; 2836d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2837116cc022SMiklos Szeredi bool excl; 2838d18e9008SMiklos Szeredi 2839d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2840d18e9008SMiklos Szeredi 2841d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2842d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 28432675a4ebSAl Viro error = -ENOENT; 2844d18e9008SMiklos Szeredi goto out; 2845d18e9008SMiklos Szeredi } 2846d18e9008SMiklos Szeredi 284762b259d8SMiklos Szeredi mode = op->mode; 2848d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2849d18e9008SMiklos Szeredi mode &= ~current_umask(); 2850d18e9008SMiklos Szeredi 2851116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2852116cc022SMiklos Szeredi if (excl) 2853d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2854d18e9008SMiklos Szeredi 2855d18e9008SMiklos Szeredi /* 2856d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2857d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2858d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2859d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2860d18e9008SMiklos Szeredi * 2861d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2862d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2863d18e9008SMiklos Szeredi */ 286464894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 286564894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 286664894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2867d18e9008SMiklos Szeredi /* 2868d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2869d18e9008SMiklos Szeredi * back to lookup + open 2870d18e9008SMiklos Szeredi */ 2871d18e9008SMiklos Szeredi goto no_open; 2872d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2873d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 287464894cf8SAl Viro create_error = -EROFS; 2875d18e9008SMiklos Szeredi goto no_open; 2876d18e9008SMiklos Szeredi } else { 2877d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 287864894cf8SAl Viro create_error = -EROFS; 2879d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2880d18e9008SMiklos Szeredi } 2881d18e9008SMiklos Szeredi } 2882d18e9008SMiklos Szeredi 2883d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 288438227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2885d18e9008SMiklos Szeredi if (error) { 2886d18e9008SMiklos Szeredi create_error = error; 2887d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2888d18e9008SMiklos Szeredi goto no_open; 2889d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2890d18e9008SMiklos Szeredi } 2891d18e9008SMiklos Szeredi } 2892d18e9008SMiklos Szeredi 2893d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2894d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2895d18e9008SMiklos Szeredi 289630d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 289730d90494SAl Viro file->f_path.mnt = nd->path.mnt; 289830d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 289947237687SAl Viro opened); 2900d9585277SAl Viro if (error < 0) { 2901d9585277SAl Viro if (create_error && error == -ENOENT) 2902d9585277SAl Viro error = create_error; 2903d18e9008SMiklos Szeredi goto out; 2904d18e9008SMiklos Szeredi } 2905d18e9008SMiklos Szeredi 2906d9585277SAl Viro if (error) { /* returned 1, that is */ 290730d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 29082675a4ebSAl Viro error = -EIO; 2909d18e9008SMiklos Szeredi goto out; 2910d18e9008SMiklos Szeredi } 291130d90494SAl Viro if (file->f_path.dentry) { 2912d18e9008SMiklos Szeredi dput(dentry); 291330d90494SAl Viro dentry = file->f_path.dentry; 2914d18e9008SMiklos Szeredi } 291503da633aSAl Viro if (*opened & FILE_CREATED) 291603da633aSAl Viro fsnotify_create(dir, dentry); 291703da633aSAl Viro if (!dentry->d_inode) { 291803da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 291903da633aSAl Viro if (create_error) { 292062b2ce96SSage Weil error = create_error; 292162b2ce96SSage Weil goto out; 292262b2ce96SSage Weil } 292303da633aSAl Viro } else { 292403da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 292503da633aSAl Viro error = -EEXIST; 292603da633aSAl Viro goto out; 292703da633aSAl Viro } 292803da633aSAl Viro } 2929d18e9008SMiklos Szeredi goto looked_up; 2930d18e9008SMiklos Szeredi } 2931d18e9008SMiklos Szeredi 2932d18e9008SMiklos Szeredi /* 2933d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2934d18e9008SMiklos Szeredi * here. 2935d18e9008SMiklos Szeredi */ 293603da633aSAl Viro acc_mode = op->acc_mode; 293703da633aSAl Viro if (*opened & FILE_CREATED) { 293803da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 293903da633aSAl Viro fsnotify_create(dir, dentry); 294062fb4a15SAl Viro acc_mode = 0; 294103da633aSAl Viro } 29422675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 29432675a4ebSAl Viro if (error) 29442675a4ebSAl Viro fput(file); 2945d18e9008SMiklos Szeredi 2946d18e9008SMiklos Szeredi out: 2947d18e9008SMiklos Szeredi dput(dentry); 29482675a4ebSAl Viro return error; 2949d18e9008SMiklos Szeredi 2950d18e9008SMiklos Szeredi no_open: 2951d18e9008SMiklos Szeredi if (need_lookup) { 295272bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2953d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 29542675a4ebSAl Viro return PTR_ERR(dentry); 2955d18e9008SMiklos Szeredi 2956d18e9008SMiklos Szeredi if (create_error) { 2957d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2958d18e9008SMiklos Szeredi 29592675a4ebSAl Viro error = create_error; 2960d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2961d18e9008SMiklos Szeredi if (!dentry->d_inode) 2962d18e9008SMiklos Szeredi goto out; 2963d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2964d18e9008SMiklos Szeredi goto out; 2965d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2966e36cb0b8SDavid Howells d_is_reg(dentry)) { 2967d18e9008SMiklos Szeredi goto out; 2968d18e9008SMiklos Szeredi } 2969d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2970d18e9008SMiklos Szeredi } 2971d18e9008SMiklos Szeredi } 2972d18e9008SMiklos Szeredi looked_up: 2973d18e9008SMiklos Szeredi path->dentry = dentry; 2974d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 29752675a4ebSAl Viro return 1; 2976d18e9008SMiklos Szeredi } 2977d18e9008SMiklos Szeredi 297831e6b01fSNick Piggin /* 29791acf0af9SDavid Howells * Look up and maybe create and open the last component. 2980d58ffd35SMiklos Szeredi * 2981d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2982d58ffd35SMiklos Szeredi * 29831acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 29841acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 29851acf0af9SDavid Howells * 29861acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 29871acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 29881acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 29891acf0af9SDavid Howells * specified then a negative dentry may be returned. 29901acf0af9SDavid Howells * 29911acf0af9SDavid Howells * An error code is returned otherwise. 29921acf0af9SDavid Howells * 29931acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 29941acf0af9SDavid Howells * cleared otherwise prior to returning. 2995d58ffd35SMiklos Szeredi */ 29962675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 299730d90494SAl Viro struct file *file, 2998d58ffd35SMiklos Szeredi const struct open_flags *op, 299964894cf8SAl Viro bool got_write, int *opened) 3000d58ffd35SMiklos Szeredi { 3001d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 300254ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 3003d58ffd35SMiklos Szeredi struct dentry *dentry; 3004d58ffd35SMiklos Szeredi int error; 30056c51e513SAl Viro bool need_lookup = false; 3006d58ffd35SMiklos Szeredi 300747237687SAl Viro *opened &= ~FILE_CREATED; 30086c51e513SAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags); 3009d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 30102675a4ebSAl Viro return PTR_ERR(dentry); 3011d58ffd35SMiklos Szeredi 30126c51e513SAl Viro if (!dentry) { 30136c51e513SAl Viro dentry = d_alloc(dir, &nd->last); 30146c51e513SAl Viro if (unlikely(!dentry)) 30156c51e513SAl Viro return -ENOMEM; 30166c51e513SAl Viro need_lookup = true; 30176c51e513SAl Viro } else if (dentry->d_inode) { 3018d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3019d18e9008SMiklos Szeredi goto out_no_open; 30206c51e513SAl Viro } 3021d18e9008SMiklos Szeredi 3022d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 302364894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 302447237687SAl Viro need_lookup, opened); 3025d18e9008SMiklos Szeredi } 3026d18e9008SMiklos Szeredi 302754ef4872SMiklos Szeredi if (need_lookup) { 302854ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 302954ef4872SMiklos Szeredi 303072bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 303154ef4872SMiklos Szeredi if (IS_ERR(dentry)) 30322675a4ebSAl Viro return PTR_ERR(dentry); 303354ef4872SMiklos Szeredi } 303454ef4872SMiklos Szeredi 3035d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 3036d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 3037d58ffd35SMiklos Szeredi umode_t mode = op->mode; 3038d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 3039d58ffd35SMiklos Szeredi mode &= ~current_umask(); 3040d58ffd35SMiklos Szeredi /* 3041d58ffd35SMiklos Szeredi * This write is needed to ensure that a 3042d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 3043d58ffd35SMiklos Szeredi * the time when the file is created and when 3044d58ffd35SMiklos Szeredi * a permanent write count is taken through 3045015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 3046d58ffd35SMiklos Szeredi */ 304764894cf8SAl Viro if (!got_write) { 304864894cf8SAl Viro error = -EROFS; 3049d58ffd35SMiklos Szeredi goto out_dput; 305064894cf8SAl Viro } 305147237687SAl Viro *opened |= FILE_CREATED; 3052d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 3053d58ffd35SMiklos Szeredi if (error) 3054d58ffd35SMiklos Szeredi goto out_dput; 3055312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 3056312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 3057d58ffd35SMiklos Szeredi if (error) 3058d58ffd35SMiklos Szeredi goto out_dput; 3059d58ffd35SMiklos Szeredi } 3060d18e9008SMiklos Szeredi out_no_open: 3061d58ffd35SMiklos Szeredi path->dentry = dentry; 3062d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 30632675a4ebSAl Viro return 1; 3064d58ffd35SMiklos Szeredi 3065d58ffd35SMiklos Szeredi out_dput: 3066d58ffd35SMiklos Szeredi dput(dentry); 30672675a4ebSAl Viro return error; 3068d58ffd35SMiklos Szeredi } 3069d58ffd35SMiklos Szeredi 3070d58ffd35SMiklos Szeredi /* 3071fe2d35ffSAl Viro * Handle the last step of open() 307231e6b01fSNick Piggin */ 3073896475d5SAl Viro static int do_last(struct nameidata *nd, 307430d90494SAl Viro struct file *file, const struct open_flags *op, 307576ae2a5aSAl Viro int *opened) 3076fb1cc555SAl Viro { 3077a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3078ca344a89SAl Viro int open_flag = op->open_flag; 307977d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 308064894cf8SAl Viro bool got_write = false; 3081bcda7652SAl Viro int acc_mode = op->acc_mode; 3082254cf582SAl Viro unsigned seq; 3083a1eb3315SMiklos Szeredi struct inode *inode; 308416b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 3085896475d5SAl Viro struct path path; 308616b1c1cdSMiklos Szeredi bool retried = false; 308716c2cd71SAl Viro int error; 3088fb1cc555SAl Viro 3089c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3090c3e380b0SAl Viro nd->flags |= op->intent; 3091c3e380b0SAl Viro 3092bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3093fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3094deb106c6SAl Viro if (unlikely(error)) 30952675a4ebSAl Viro return error; 3096e83db167SMiklos Szeredi goto finish_open; 30971f36f774SAl Viro } 3098a2c36b45SAl Viro 3099ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3100fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3101fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3102fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3103254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 3104e9742b53SAl Viro if (likely(error > 0)) 310571574865SMiklos Szeredi goto finish_lookup; 310671574865SMiklos Szeredi 3107ce57dfc1SAl Viro if (error < 0) 3108deb106c6SAl Viro return error; 3109a1eb3315SMiklos Szeredi 311037d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 31116583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3112b6183df7SMiklos Szeredi } else { 3113fe2d35ffSAl Viro /* create side of things */ 3114a3fbbde7SAl Viro /* 3115b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3116b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3117b6183df7SMiklos Szeredi * about to look up 3118a3fbbde7SAl Viro */ 31199f1fafeeSAl Viro error = complete_walk(nd); 3120e8bb73dfSAl Viro if (error) 31212675a4ebSAl Viro return error; 3122fe2d35ffSAl Viro 312376ae2a5aSAl Viro audit_inode(nd->name, dir, LOOKUP_PARENT); 31241f36f774SAl Viro /* trailing slashes? */ 3125deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3126deb106c6SAl Viro return -EISDIR; 3127b6183df7SMiklos Szeredi } 31281f36f774SAl Viro 312916b1c1cdSMiklos Szeredi retry_lookup: 313064894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 313164894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 313264894cf8SAl Viro if (!error) 313364894cf8SAl Viro got_write = true; 313464894cf8SAl Viro /* 313564894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 313664894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 313764894cf8SAl Viro * dropping this one anyway. 313864894cf8SAl Viro */ 313964894cf8SAl Viro } 31405955102cSAl Viro inode_lock(dir->d_inode); 3141896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 31425955102cSAl Viro inode_unlock(dir->d_inode); 3143fb1cc555SAl Viro 31442675a4ebSAl Viro if (error <= 0) { 31452675a4ebSAl Viro if (error) 3146d58ffd35SMiklos Szeredi goto out; 31476c0d46c4SAl Viro 314847237687SAl Viro if ((*opened & FILE_CREATED) || 3149496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 315077d660a8SMiklos Szeredi will_truncate = false; 3151d18e9008SMiklos Szeredi 315276ae2a5aSAl Viro audit_inode(nd->name, file->f_path.dentry, 0); 3153d18e9008SMiklos Szeredi goto opened; 3154d18e9008SMiklos Szeredi } 3155d18e9008SMiklos Szeredi 315647237687SAl Viro if (*opened & FILE_CREATED) { 31579b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3158ca344a89SAl Viro open_flag &= ~O_TRUNC; 315977d660a8SMiklos Szeredi will_truncate = false; 316062fb4a15SAl Viro acc_mode = 0; 3161896475d5SAl Viro path_to_nameidata(&path, nd); 3162e83db167SMiklos Szeredi goto finish_open_created; 3163fb1cc555SAl Viro } 3164fb1cc555SAl Viro 3165fb1cc555SAl Viro /* 3166d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3167d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3168d18e9008SMiklos Szeredi * necessary...) 3169d18e9008SMiklos Szeredi */ 317064894cf8SAl Viro if (got_write) { 3171d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 317264894cf8SAl Viro got_write = false; 3173d18e9008SMiklos Szeredi } 3174d18e9008SMiklos Szeredi 31756583fe22SAl Viro if (unlikely(d_is_negative(path.dentry))) { 31766583fe22SAl Viro path_to_nameidata(&path, nd); 31776583fe22SAl Viro return -ENOENT; 31786583fe22SAl Viro } 31796583fe22SAl Viro 31806583fe22SAl Viro /* 31816583fe22SAl Viro * create/update audit record if it already exists. 31826583fe22SAl Viro */ 31836583fe22SAl Viro audit_inode(nd->name, path.dentry, 0); 31846583fe22SAl Viro 3185deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3186deb106c6SAl Viro path_to_nameidata(&path, nd); 3187deb106c6SAl Viro return -EEXIST; 3188deb106c6SAl Viro } 3189fb1cc555SAl Viro 3190756daf26SNeilBrown error = follow_managed(&path, nd); 3191deb106c6SAl Viro if (unlikely(error < 0)) 3192deb106c6SAl Viro return error; 3193a3fbbde7SAl Viro 3194254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3195d4565649SAl Viro inode = d_backing_inode(path.dentry); 3196766c4cbfSAl Viro finish_lookup: 3197191d7f73SAl Viro if (nd->depth) 3198191d7f73SAl Viro put_link(nd); 3199181548c0SAl Viro error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW, 3200181548c0SAl Viro inode, seq); 3201deb106c6SAl Viro if (unlikely(error)) 3202d63ff28fSAl Viro return error; 3203fb1cc555SAl Viro 3204896475d5SAl Viro if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { 3205896475d5SAl Viro path_to_nameidata(&path, nd); 320616b1c1cdSMiklos Szeredi } else { 320716b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 3208896475d5SAl Viro save_parent.mnt = mntget(path.mnt); 3209896475d5SAl Viro nd->path.dentry = path.dentry; 321016b1c1cdSMiklos Szeredi 321116b1c1cdSMiklos Szeredi } 3212decf3400SMiklos Szeredi nd->inode = inode; 3213254cf582SAl Viro nd->seq = seq; 3214a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3215bc77daa7SAl Viro finish_open: 3216a3fbbde7SAl Viro error = complete_walk(nd); 321716b1c1cdSMiklos Szeredi if (error) { 321816b1c1cdSMiklos Szeredi path_put(&save_parent); 32192675a4ebSAl Viro return error; 322016b1c1cdSMiklos Szeredi } 322176ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 32225129fa48SAl Viro if (unlikely(d_is_symlink(nd->path.dentry)) && !(open_flag & O_PATH)) { 32235129fa48SAl Viro error = -ELOOP; 32245129fa48SAl Viro goto out; 32255129fa48SAl Viro } 3226fb1cc555SAl Viro error = -EISDIR; 322744b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 32282675a4ebSAl Viro goto out; 3229af2f5542SMiklos Szeredi error = -ENOTDIR; 323044b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 32312675a4ebSAl Viro goto out; 32324bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 323377d660a8SMiklos Szeredi will_truncate = false; 32346c0d46c4SAl Viro 32350f9d1a10SAl Viro if (will_truncate) { 32360f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 32370f9d1a10SAl Viro if (error) 32382675a4ebSAl Viro goto out; 323964894cf8SAl Viro got_write = true; 32400f9d1a10SAl Viro } 3241e83db167SMiklos Szeredi finish_open_created: 324262fb4a15SAl Viro if (likely(!(open_flag & O_PATH))) { 3243bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3244ca344a89SAl Viro if (error) 32452675a4ebSAl Viro goto out; 324662fb4a15SAl Viro } 32474aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 32484aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 32494aa7c634SMiklos Szeredi if (!error) { 32504aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 32514aa7c634SMiklos Szeredi } else { 325230d90494SAl Viro if (error == -EOPENSTALE) 3253f60dc3dbSMiklos Szeredi goto stale_open; 3254015c3bbcSMiklos Szeredi goto out; 3255f60dc3dbSMiklos Szeredi } 3256a8277b9bSMiklos Szeredi opened: 32572675a4ebSAl Viro error = open_check_o_direct(file); 3258015c3bbcSMiklos Szeredi if (error) 3259015c3bbcSMiklos Szeredi goto exit_fput; 32603034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3261aa4caadbSMiklos Szeredi if (error) 3262aa4caadbSMiklos Szeredi goto exit_fput; 3263aa4caadbSMiklos Szeredi 32640f9d1a10SAl Viro if (will_truncate) { 32652675a4ebSAl Viro error = handle_truncate(file); 3266aa4caadbSMiklos Szeredi if (error) 3267aa4caadbSMiklos Szeredi goto exit_fput; 32680f9d1a10SAl Viro } 3269ca344a89SAl Viro out: 3270c80567c8SAl Viro if (unlikely(error > 0)) { 3271c80567c8SAl Viro WARN_ON(1); 3272c80567c8SAl Viro error = -EINVAL; 3273c80567c8SAl Viro } 327464894cf8SAl Viro if (got_write) 32750f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 327616b1c1cdSMiklos Szeredi path_put(&save_parent); 32772675a4ebSAl Viro return error; 3278fb1cc555SAl Viro 3279015c3bbcSMiklos Szeredi exit_fput: 32802675a4ebSAl Viro fput(file); 32812675a4ebSAl Viro goto out; 3282015c3bbcSMiklos Szeredi 3283f60dc3dbSMiklos Szeredi stale_open: 3284f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3285f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3286f60dc3dbSMiklos Szeredi goto out; 3287f60dc3dbSMiklos Szeredi 3288f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3289f60dc3dbSMiklos Szeredi path_put(&nd->path); 3290f60dc3dbSMiklos Szeredi nd->path = save_parent; 3291f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3292f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3293f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 329464894cf8SAl Viro if (got_write) { 3295f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 329664894cf8SAl Viro got_write = false; 3297f60dc3dbSMiklos Szeredi } 3298f60dc3dbSMiklos Szeredi retried = true; 3299f60dc3dbSMiklos Szeredi goto retry_lookup; 3300fb1cc555SAl Viro } 3301fb1cc555SAl Viro 3302c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 330360545d0dSAl Viro const struct open_flags *op, 330460545d0dSAl Viro struct file *file, int *opened) 330560545d0dSAl Viro { 330660545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 3307625b6d10SAl Viro struct dentry *child; 330860545d0dSAl Viro struct inode *dir; 3309625b6d10SAl Viro struct path path; 3310c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 331160545d0dSAl Viro if (unlikely(error)) 331260545d0dSAl Viro return error; 3313625b6d10SAl Viro error = mnt_want_write(path.mnt); 331460545d0dSAl Viro if (unlikely(error)) 331560545d0dSAl Viro goto out; 3316625b6d10SAl Viro dir = path.dentry->d_inode; 331760545d0dSAl Viro /* we want directory to be writable */ 3318625b6d10SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 331960545d0dSAl Viro if (error) 332060545d0dSAl Viro goto out2; 332160545d0dSAl Viro if (!dir->i_op->tmpfile) { 332260545d0dSAl Viro error = -EOPNOTSUPP; 332360545d0dSAl Viro goto out2; 332460545d0dSAl Viro } 3325625b6d10SAl Viro child = d_alloc(path.dentry, &name); 332660545d0dSAl Viro if (unlikely(!child)) { 332760545d0dSAl Viro error = -ENOMEM; 332860545d0dSAl Viro goto out2; 332960545d0dSAl Viro } 3330625b6d10SAl Viro dput(path.dentry); 3331625b6d10SAl Viro path.dentry = child; 3332625b6d10SAl Viro error = dir->i_op->tmpfile(dir, child, op->mode); 333360545d0dSAl Viro if (error) 333460545d0dSAl Viro goto out2; 3335c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 333669a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 333762fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 333860545d0dSAl Viro if (error) 333960545d0dSAl Viro goto out2; 3340625b6d10SAl Viro file->f_path.mnt = path.mnt; 3341625b6d10SAl Viro error = finish_open(file, child, NULL, opened); 334260545d0dSAl Viro if (error) 334360545d0dSAl Viro goto out2; 334460545d0dSAl Viro error = open_check_o_direct(file); 3345f4e0c30cSAl Viro if (error) { 334660545d0dSAl Viro fput(file); 3347f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3348f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3349f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3350f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3351f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3352f4e0c30cSAl Viro } 335360545d0dSAl Viro out2: 3354625b6d10SAl Viro mnt_drop_write(path.mnt); 335560545d0dSAl Viro out: 3356625b6d10SAl Viro path_put(&path); 335760545d0dSAl Viro return error; 335860545d0dSAl Viro } 335960545d0dSAl Viro 3360c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3361c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 33621da177e4SLinus Torvalds { 3363368ee9baSAl Viro const char *s; 336430d90494SAl Viro struct file *file; 336547237687SAl Viro int opened = 0; 336613aab428SAl Viro int error; 336731e6b01fSNick Piggin 336830d90494SAl Viro file = get_empty_filp(); 33691afc99beSAl Viro if (IS_ERR(file)) 33701afc99beSAl Viro return file; 337131e6b01fSNick Piggin 337230d90494SAl Viro file->f_flags = op->open_flag; 337331e6b01fSNick Piggin 3374bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 3375c8a53ee5SAl Viro error = do_tmpfile(nd, flags, op, file, &opened); 3376f15133dfSAl Viro goto out2; 337760545d0dSAl Viro } 337860545d0dSAl Viro 3379c8a53ee5SAl Viro s = path_init(nd, flags); 3380368ee9baSAl Viro if (IS_ERR(s)) { 3381368ee9baSAl Viro put_filp(file); 3382368ee9baSAl Viro return ERR_CAST(s); 3383368ee9baSAl Viro } 33843bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 338576ae2a5aSAl Viro (error = do_last(nd, file, op, &opened)) > 0) { 338673d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 33873bdba28bSAl Viro s = trailing_symlink(nd); 33883bdba28bSAl Viro if (IS_ERR(s)) { 33893bdba28bSAl Viro error = PTR_ERR(s); 33902675a4ebSAl Viro break; 3391806b681cSAl Viro } 33923bdba28bSAl Viro } 3393deb106c6SAl Viro terminate_walk(nd); 3394f15133dfSAl Viro out2: 33952675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 33962675a4ebSAl Viro BUG_ON(!error); 339730d90494SAl Viro put_filp(file); 3398015c3bbcSMiklos Szeredi } 33992675a4ebSAl Viro if (unlikely(error)) { 34002675a4ebSAl Viro if (error == -EOPENSTALE) { 34012675a4ebSAl Viro if (flags & LOOKUP_RCU) 34022675a4ebSAl Viro error = -ECHILD; 34032675a4ebSAl Viro else 34042675a4ebSAl Viro error = -ESTALE; 34052675a4ebSAl Viro } 34062675a4ebSAl Viro file = ERR_PTR(error); 34072675a4ebSAl Viro } 34082675a4ebSAl Viro return file; 3409de459215SKirill Korotaev } 34101da177e4SLinus Torvalds 3411669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3412f9652e10SAl Viro const struct open_flags *op) 341313aab428SAl Viro { 34149883d185SAl Viro struct nameidata nd; 3415f9652e10SAl Viro int flags = op->lookup_flags; 341613aab428SAl Viro struct file *filp; 341713aab428SAl Viro 34189883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3419c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 342013aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3421c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 342213aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3423c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 34249883d185SAl Viro restore_nameidata(); 342513aab428SAl Viro return filp; 342613aab428SAl Viro } 342713aab428SAl Viro 342873d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3429f9652e10SAl Viro const char *name, const struct open_flags *op) 343073d049a4SAl Viro { 34319883d185SAl Viro struct nameidata nd; 343273d049a4SAl Viro struct file *file; 343351689104SPaul Moore struct filename *filename; 3434f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 343573d049a4SAl Viro 343673d049a4SAl Viro nd.root.mnt = mnt; 343773d049a4SAl Viro nd.root.dentry = dentry; 343873d049a4SAl Viro 3439b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 344073d049a4SAl Viro return ERR_PTR(-ELOOP); 344173d049a4SAl Viro 344251689104SPaul Moore filename = getname_kernel(name); 3443a1c83681SViresh Kumar if (IS_ERR(filename)) 344451689104SPaul Moore return ERR_CAST(filename); 344551689104SPaul Moore 34469883d185SAl Viro set_nameidata(&nd, -1, filename); 3447c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 344873d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3449c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 345073d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3451c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 34529883d185SAl Viro restore_nameidata(); 345351689104SPaul Moore putname(filename); 345473d049a4SAl Viro return file; 345573d049a4SAl Viro } 345673d049a4SAl Viro 3457fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 34581ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 34591da177e4SLinus Torvalds { 3460c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3461391172c4SAl Viro struct qstr last; 3462391172c4SAl Viro int type; 3463c30dabfeSJan Kara int err2; 34641ac12b4bSJeff Layton int error; 34651ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 34661ac12b4bSJeff Layton 34671ac12b4bSJeff Layton /* 34681ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 34691ac12b4bSJeff Layton * other flags passed in are ignored! 34701ac12b4bSJeff Layton */ 34711ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 34721ac12b4bSJeff Layton 34735c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 34745c31b6ceSAl Viro if (IS_ERR(name)) 34755c31b6ceSAl Viro return ERR_CAST(name); 34761da177e4SLinus Torvalds 3477c663e5d8SChristoph Hellwig /* 3478c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3479c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3480c663e5d8SChristoph Hellwig */ 34815c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3482ed75e95dSAl Viro goto out; 3483c663e5d8SChristoph Hellwig 3484c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3485391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3486c663e5d8SChristoph Hellwig /* 3487c663e5d8SChristoph Hellwig * Do the final lookup. 3488c663e5d8SChristoph Hellwig */ 3489391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 34905955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3491391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 34921da177e4SLinus Torvalds if (IS_ERR(dentry)) 3493a8104a9fSAl Viro goto unlock; 3494c663e5d8SChristoph Hellwig 3495a8104a9fSAl Viro error = -EEXIST; 3496b18825a7SDavid Howells if (d_is_positive(dentry)) 3497a8104a9fSAl Viro goto fail; 3498b18825a7SDavid Howells 3499c663e5d8SChristoph Hellwig /* 3500c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3501c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3502c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3503c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3504c663e5d8SChristoph Hellwig */ 3505391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3506a8104a9fSAl Viro error = -ENOENT; 3507ed75e95dSAl Viro goto fail; 3508e9baf6e5SAl Viro } 3509c30dabfeSJan Kara if (unlikely(err2)) { 3510c30dabfeSJan Kara error = err2; 3511a8104a9fSAl Viro goto fail; 3512c30dabfeSJan Kara } 3513181c37b6SAl Viro putname(name); 3514e9baf6e5SAl Viro return dentry; 35151da177e4SLinus Torvalds fail: 3516a8104a9fSAl Viro dput(dentry); 3517a8104a9fSAl Viro dentry = ERR_PTR(error); 3518a8104a9fSAl Viro unlock: 35195955102cSAl Viro inode_unlock(path->dentry->d_inode); 3520c30dabfeSJan Kara if (!err2) 3521391172c4SAl Viro mnt_drop_write(path->mnt); 3522ed75e95dSAl Viro out: 3523391172c4SAl Viro path_put(path); 3524181c37b6SAl Viro putname(name); 3525ed75e95dSAl Viro return dentry; 3526dae6ad8fSAl Viro } 3527fa14a0b8SAl Viro 3528fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3529fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3530fa14a0b8SAl Viro { 3531181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3532181c37b6SAl Viro path, lookup_flags); 3533fa14a0b8SAl Viro } 3534dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3535dae6ad8fSAl Viro 3536921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3537921a1650SAl Viro { 3538921a1650SAl Viro dput(dentry); 35395955102cSAl Viro inode_unlock(path->dentry->d_inode); 3540a8104a9fSAl Viro mnt_drop_write(path->mnt); 3541921a1650SAl Viro path_put(path); 3542921a1650SAl Viro } 3543921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3544921a1650SAl Viro 3545520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 35461ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3547dae6ad8fSAl Viro { 3548181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3549dae6ad8fSAl Viro } 3550dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3551dae6ad8fSAl Viro 35521a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 35531da177e4SLinus Torvalds { 3554a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35551da177e4SLinus Torvalds 35561da177e4SLinus Torvalds if (error) 35571da177e4SLinus Torvalds return error; 35581da177e4SLinus Torvalds 3559975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 35601da177e4SLinus Torvalds return -EPERM; 35611da177e4SLinus Torvalds 3562acfa4380SAl Viro if (!dir->i_op->mknod) 35631da177e4SLinus Torvalds return -EPERM; 35641da177e4SLinus Torvalds 356508ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 356608ce5f16SSerge E. Hallyn if (error) 356708ce5f16SSerge E. Hallyn return error; 356808ce5f16SSerge E. Hallyn 35691da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 35701da177e4SLinus Torvalds if (error) 35711da177e4SLinus Torvalds return error; 35721da177e4SLinus Torvalds 35731da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3574a74574aaSStephen Smalley if (!error) 3575f38aa942SAmy Griffis fsnotify_create(dir, dentry); 35761da177e4SLinus Torvalds return error; 35771da177e4SLinus Torvalds } 35784d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 35791da177e4SLinus Torvalds 3580f69aac00SAl Viro static int may_mknod(umode_t mode) 3581463c3197SDave Hansen { 3582463c3197SDave Hansen switch (mode & S_IFMT) { 3583463c3197SDave Hansen case S_IFREG: 3584463c3197SDave Hansen case S_IFCHR: 3585463c3197SDave Hansen case S_IFBLK: 3586463c3197SDave Hansen case S_IFIFO: 3587463c3197SDave Hansen case S_IFSOCK: 3588463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3589463c3197SDave Hansen return 0; 3590463c3197SDave Hansen case S_IFDIR: 3591463c3197SDave Hansen return -EPERM; 3592463c3197SDave Hansen default: 3593463c3197SDave Hansen return -EINVAL; 3594463c3197SDave Hansen } 3595463c3197SDave Hansen } 3596463c3197SDave Hansen 35978208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 35982e4d0924SHeiko Carstens unsigned, dev) 35991da177e4SLinus Torvalds { 36001da177e4SLinus Torvalds struct dentry *dentry; 3601dae6ad8fSAl Viro struct path path; 3602dae6ad8fSAl Viro int error; 3603972567f1SJeff Layton unsigned int lookup_flags = 0; 36041da177e4SLinus Torvalds 36058e4bfca1SAl Viro error = may_mknod(mode); 36068e4bfca1SAl Viro if (error) 36078e4bfca1SAl Viro return error; 3608972567f1SJeff Layton retry: 3609972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3610dae6ad8fSAl Viro if (IS_ERR(dentry)) 3611dae6ad8fSAl Viro return PTR_ERR(dentry); 36122ad94ae6SAl Viro 3613dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3614ce3b0f8dSAl Viro mode &= ~current_umask(); 3615dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3616be6d3e56SKentaro Takeda if (error) 3617a8104a9fSAl Viro goto out; 36181da177e4SLinus Torvalds switch (mode & S_IFMT) { 36191da177e4SLinus Torvalds case 0: case S_IFREG: 3620312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 36211da177e4SLinus Torvalds break; 36221da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3623dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 36241da177e4SLinus Torvalds new_decode_dev(dev)); 36251da177e4SLinus Torvalds break; 36261da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3627dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 36281da177e4SLinus Torvalds break; 36291da177e4SLinus Torvalds } 3630a8104a9fSAl Viro out: 3631921a1650SAl Viro done_path_create(&path, dentry); 3632972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3633972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3634972567f1SJeff Layton goto retry; 3635972567f1SJeff Layton } 36361da177e4SLinus Torvalds return error; 36371da177e4SLinus Torvalds } 36381da177e4SLinus Torvalds 36398208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 36405590ff0dSUlrich Drepper { 36415590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 36425590ff0dSUlrich Drepper } 36435590ff0dSUlrich Drepper 364418bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 36451da177e4SLinus Torvalds { 3646a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36478de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 36481da177e4SLinus Torvalds 36491da177e4SLinus Torvalds if (error) 36501da177e4SLinus Torvalds return error; 36511da177e4SLinus Torvalds 3652acfa4380SAl Viro if (!dir->i_op->mkdir) 36531da177e4SLinus Torvalds return -EPERM; 36541da177e4SLinus Torvalds 36551da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 36561da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 36571da177e4SLinus Torvalds if (error) 36581da177e4SLinus Torvalds return error; 36591da177e4SLinus Torvalds 36608de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 36618de52778SAl Viro return -EMLINK; 36628de52778SAl Viro 36631da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3664a74574aaSStephen Smalley if (!error) 3665f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 36661da177e4SLinus Torvalds return error; 36671da177e4SLinus Torvalds } 36684d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 36691da177e4SLinus Torvalds 3670a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 36711da177e4SLinus Torvalds { 36726902d925SDave Hansen struct dentry *dentry; 3673dae6ad8fSAl Viro struct path path; 3674dae6ad8fSAl Viro int error; 3675b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 36761da177e4SLinus Torvalds 3677b76d8b82SJeff Layton retry: 3678b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 36796902d925SDave Hansen if (IS_ERR(dentry)) 3680dae6ad8fSAl Viro return PTR_ERR(dentry); 36816902d925SDave Hansen 3682dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3683ce3b0f8dSAl Viro mode &= ~current_umask(); 3684dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3685a8104a9fSAl Viro if (!error) 3686dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3687921a1650SAl Viro done_path_create(&path, dentry); 3688b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3689b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3690b76d8b82SJeff Layton goto retry; 3691b76d8b82SJeff Layton } 36921da177e4SLinus Torvalds return error; 36931da177e4SLinus Torvalds } 36941da177e4SLinus Torvalds 3695a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 36965590ff0dSUlrich Drepper { 36975590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 36985590ff0dSUlrich Drepper } 36995590ff0dSUlrich Drepper 37001da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 37011da177e4SLinus Torvalds { 37021da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 37031da177e4SLinus Torvalds 37041da177e4SLinus Torvalds if (error) 37051da177e4SLinus Torvalds return error; 37061da177e4SLinus Torvalds 3707acfa4380SAl Viro if (!dir->i_op->rmdir) 37081da177e4SLinus Torvalds return -EPERM; 37091da177e4SLinus Torvalds 37101d2ef590SAl Viro dget(dentry); 37115955102cSAl Viro inode_lock(dentry->d_inode); 3712912dbc15SSage Weil 37131da177e4SLinus Torvalds error = -EBUSY; 37147af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3715912dbc15SSage Weil goto out; 3716912dbc15SSage Weil 37171da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3718912dbc15SSage Weil if (error) 3719912dbc15SSage Weil goto out; 3720912dbc15SSage Weil 37213cebde24SSage Weil shrink_dcache_parent(dentry); 37221da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3723912dbc15SSage Weil if (error) 3724912dbc15SSage Weil goto out; 3725912dbc15SSage Weil 37261da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3727d83c49f3SAl Viro dont_mount(dentry); 37288ed936b5SEric W. Biederman detach_mounts(dentry); 37291da177e4SLinus Torvalds 3730912dbc15SSage Weil out: 37315955102cSAl Viro inode_unlock(dentry->d_inode); 37321d2ef590SAl Viro dput(dentry); 3733912dbc15SSage Weil if (!error) 3734912dbc15SSage Weil d_delete(dentry); 37351da177e4SLinus Torvalds return error; 37361da177e4SLinus Torvalds } 37374d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 37381da177e4SLinus Torvalds 37395590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 37401da177e4SLinus Torvalds { 37411da177e4SLinus Torvalds int error = 0; 374291a27b2aSJeff Layton struct filename *name; 37431da177e4SLinus Torvalds struct dentry *dentry; 3744f5beed75SAl Viro struct path path; 3745f5beed75SAl Viro struct qstr last; 3746f5beed75SAl Viro int type; 3747c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3748c6ee9206SJeff Layton retry: 3749f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3750f5beed75SAl Viro &path, &last, &type, lookup_flags); 375191a27b2aSJeff Layton if (IS_ERR(name)) 375291a27b2aSJeff Layton return PTR_ERR(name); 37531da177e4SLinus Torvalds 3754f5beed75SAl Viro switch (type) { 37551da177e4SLinus Torvalds case LAST_DOTDOT: 37561da177e4SLinus Torvalds error = -ENOTEMPTY; 37571da177e4SLinus Torvalds goto exit1; 37581da177e4SLinus Torvalds case LAST_DOT: 37591da177e4SLinus Torvalds error = -EINVAL; 37601da177e4SLinus Torvalds goto exit1; 37611da177e4SLinus Torvalds case LAST_ROOT: 37621da177e4SLinus Torvalds error = -EBUSY; 37631da177e4SLinus Torvalds goto exit1; 37641da177e4SLinus Torvalds } 37650612d9fbSOGAWA Hirofumi 3766f5beed75SAl Viro error = mnt_want_write(path.mnt); 3767c30dabfeSJan Kara if (error) 3768c30dabfeSJan Kara goto exit1; 37690612d9fbSOGAWA Hirofumi 37705955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3771f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 37721da177e4SLinus Torvalds error = PTR_ERR(dentry); 37736902d925SDave Hansen if (IS_ERR(dentry)) 37746902d925SDave Hansen goto exit2; 3775e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3776e6bc45d6STheodore Ts'o error = -ENOENT; 3777e6bc45d6STheodore Ts'o goto exit3; 3778e6bc45d6STheodore Ts'o } 3779f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3780be6d3e56SKentaro Takeda if (error) 3781c30dabfeSJan Kara goto exit3; 3782f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 37830622753bSDave Hansen exit3: 37841da177e4SLinus Torvalds dput(dentry); 37856902d925SDave Hansen exit2: 37865955102cSAl Viro inode_unlock(path.dentry->d_inode); 3787f5beed75SAl Viro mnt_drop_write(path.mnt); 37881da177e4SLinus Torvalds exit1: 3789f5beed75SAl Viro path_put(&path); 37901da177e4SLinus Torvalds putname(name); 3791c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3792c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3793c6ee9206SJeff Layton goto retry; 3794c6ee9206SJeff Layton } 37951da177e4SLinus Torvalds return error; 37961da177e4SLinus Torvalds } 37971da177e4SLinus Torvalds 37983cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 37995590ff0dSUlrich Drepper { 38005590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 38015590ff0dSUlrich Drepper } 38025590ff0dSUlrich Drepper 3803b21996e3SJ. Bruce Fields /** 3804b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3805b21996e3SJ. Bruce Fields * @dir: parent directory 3806b21996e3SJ. Bruce Fields * @dentry: victim 3807b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3808b21996e3SJ. Bruce Fields * 3809b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3810b21996e3SJ. Bruce Fields * 3811b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3812b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3813b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3814b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3815b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3816b21996e3SJ. Bruce Fields * 3817b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3818b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3819b21996e3SJ. Bruce Fields * to be NFS exported. 3820b21996e3SJ. Bruce Fields */ 3821b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 38221da177e4SLinus Torvalds { 38239accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 38241da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 38251da177e4SLinus Torvalds 38261da177e4SLinus Torvalds if (error) 38271da177e4SLinus Torvalds return error; 38281da177e4SLinus Torvalds 3829acfa4380SAl Viro if (!dir->i_op->unlink) 38301da177e4SLinus Torvalds return -EPERM; 38311da177e4SLinus Torvalds 38325955102cSAl Viro inode_lock(target); 38338ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 38341da177e4SLinus Torvalds error = -EBUSY; 38351da177e4SLinus Torvalds else { 38361da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3837bec1052eSAl Viro if (!error) { 38385a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 38395a14696cSJ. Bruce Fields if (error) 3840b21996e3SJ. Bruce Fields goto out; 38411da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 38428ed936b5SEric W. Biederman if (!error) { 3843d83c49f3SAl Viro dont_mount(dentry); 38448ed936b5SEric W. Biederman detach_mounts(dentry); 38458ed936b5SEric W. Biederman } 3846bec1052eSAl Viro } 38471da177e4SLinus Torvalds } 3848b21996e3SJ. Bruce Fields out: 38495955102cSAl Viro inode_unlock(target); 38501da177e4SLinus Torvalds 38511da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 38521da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 38539accbb97SJ. Bruce Fields fsnotify_link_count(target); 38541da177e4SLinus Torvalds d_delete(dentry); 38551da177e4SLinus Torvalds } 38560eeca283SRobert Love 38571da177e4SLinus Torvalds return error; 38581da177e4SLinus Torvalds } 38594d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 38601da177e4SLinus Torvalds 38611da177e4SLinus Torvalds /* 38621da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 38631b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 38641da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 38651da177e4SLinus Torvalds * while waiting on the I/O. 38661da177e4SLinus Torvalds */ 38675590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 38681da177e4SLinus Torvalds { 38692ad94ae6SAl Viro int error; 387091a27b2aSJeff Layton struct filename *name; 38711da177e4SLinus Torvalds struct dentry *dentry; 3872f5beed75SAl Viro struct path path; 3873f5beed75SAl Viro struct qstr last; 3874f5beed75SAl Viro int type; 38751da177e4SLinus Torvalds struct inode *inode = NULL; 3876b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 38775d18f813SJeff Layton unsigned int lookup_flags = 0; 38785d18f813SJeff Layton retry: 3879f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3880f5beed75SAl Viro &path, &last, &type, lookup_flags); 388191a27b2aSJeff Layton if (IS_ERR(name)) 388291a27b2aSJeff Layton return PTR_ERR(name); 38832ad94ae6SAl Viro 38841da177e4SLinus Torvalds error = -EISDIR; 3885f5beed75SAl Viro if (type != LAST_NORM) 38861da177e4SLinus Torvalds goto exit1; 38870612d9fbSOGAWA Hirofumi 3888f5beed75SAl Viro error = mnt_want_write(path.mnt); 3889c30dabfeSJan Kara if (error) 3890c30dabfeSJan Kara goto exit1; 3891b21996e3SJ. Bruce Fields retry_deleg: 38925955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3893f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38941da177e4SLinus Torvalds error = PTR_ERR(dentry); 38951da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 38961da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3897f5beed75SAl Viro if (last.name[last.len]) 389850338b88STörök Edwin goto slashes; 38991da177e4SLinus Torvalds inode = dentry->d_inode; 3900b18825a7SDavid Howells if (d_is_negative(dentry)) 3901e6bc45d6STheodore Ts'o goto slashes; 39027de9c6eeSAl Viro ihold(inode); 3903f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3904be6d3e56SKentaro Takeda if (error) 3905c30dabfeSJan Kara goto exit2; 3906f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 39071da177e4SLinus Torvalds exit2: 39081da177e4SLinus Torvalds dput(dentry); 39091da177e4SLinus Torvalds } 39105955102cSAl Viro inode_unlock(path.dentry->d_inode); 39111da177e4SLinus Torvalds if (inode) 39121da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3913b21996e3SJ. Bruce Fields inode = NULL; 3914b21996e3SJ. Bruce Fields if (delegated_inode) { 39155a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3916b21996e3SJ. Bruce Fields if (!error) 3917b21996e3SJ. Bruce Fields goto retry_deleg; 3918b21996e3SJ. Bruce Fields } 3919f5beed75SAl Viro mnt_drop_write(path.mnt); 39201da177e4SLinus Torvalds exit1: 3921f5beed75SAl Viro path_put(&path); 39221da177e4SLinus Torvalds putname(name); 39235d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 39245d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 39255d18f813SJeff Layton inode = NULL; 39265d18f813SJeff Layton goto retry; 39275d18f813SJeff Layton } 39281da177e4SLinus Torvalds return error; 39291da177e4SLinus Torvalds 39301da177e4SLinus Torvalds slashes: 3931b18825a7SDavid Howells if (d_is_negative(dentry)) 3932b18825a7SDavid Howells error = -ENOENT; 393344b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3934b18825a7SDavid Howells error = -EISDIR; 3935b18825a7SDavid Howells else 3936b18825a7SDavid Howells error = -ENOTDIR; 39371da177e4SLinus Torvalds goto exit2; 39381da177e4SLinus Torvalds } 39391da177e4SLinus Torvalds 39402e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 39415590ff0dSUlrich Drepper { 39425590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 39435590ff0dSUlrich Drepper return -EINVAL; 39445590ff0dSUlrich Drepper 39455590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 39465590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 39475590ff0dSUlrich Drepper 39485590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 39495590ff0dSUlrich Drepper } 39505590ff0dSUlrich Drepper 39513480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 39525590ff0dSUlrich Drepper { 39535590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 39545590ff0dSUlrich Drepper } 39555590ff0dSUlrich Drepper 3956db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 39571da177e4SLinus Torvalds { 3958a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 39591da177e4SLinus Torvalds 39601da177e4SLinus Torvalds if (error) 39611da177e4SLinus Torvalds return error; 39621da177e4SLinus Torvalds 3963acfa4380SAl Viro if (!dir->i_op->symlink) 39641da177e4SLinus Torvalds return -EPERM; 39651da177e4SLinus Torvalds 39661da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 39671da177e4SLinus Torvalds if (error) 39681da177e4SLinus Torvalds return error; 39691da177e4SLinus Torvalds 39701da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3971a74574aaSStephen Smalley if (!error) 3972f38aa942SAmy Griffis fsnotify_create(dir, dentry); 39731da177e4SLinus Torvalds return error; 39741da177e4SLinus Torvalds } 39754d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 39761da177e4SLinus Torvalds 39772e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 39782e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 39791da177e4SLinus Torvalds { 39802ad94ae6SAl Viro int error; 398191a27b2aSJeff Layton struct filename *from; 39826902d925SDave Hansen struct dentry *dentry; 3983dae6ad8fSAl Viro struct path path; 3984f46d3567SJeff Layton unsigned int lookup_flags = 0; 39851da177e4SLinus Torvalds 39861da177e4SLinus Torvalds from = getname(oldname); 39871da177e4SLinus Torvalds if (IS_ERR(from)) 39881da177e4SLinus Torvalds return PTR_ERR(from); 3989f46d3567SJeff Layton retry: 3990f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 39911da177e4SLinus Torvalds error = PTR_ERR(dentry); 39926902d925SDave Hansen if (IS_ERR(dentry)) 3993dae6ad8fSAl Viro goto out_putname; 39946902d925SDave Hansen 399591a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3996a8104a9fSAl Viro if (!error) 399791a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3998921a1650SAl Viro done_path_create(&path, dentry); 3999f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4000f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4001f46d3567SJeff Layton goto retry; 4002f46d3567SJeff Layton } 40036902d925SDave Hansen out_putname: 40041da177e4SLinus Torvalds putname(from); 40051da177e4SLinus Torvalds return error; 40061da177e4SLinus Torvalds } 40071da177e4SLinus Torvalds 40083480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 40095590ff0dSUlrich Drepper { 40105590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 40115590ff0dSUlrich Drepper } 40125590ff0dSUlrich Drepper 4013146a8595SJ. Bruce Fields /** 4014146a8595SJ. Bruce Fields * vfs_link - create a new link 4015146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4016146a8595SJ. Bruce Fields * @dir: new parent 4017146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4018146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4019146a8595SJ. Bruce Fields * 4020146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4021146a8595SJ. Bruce Fields * 4022146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4023146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4024146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4025146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4026146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4027146a8595SJ. Bruce Fields * 4028146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4029146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4030146a8595SJ. Bruce Fields * to be NFS exported. 4031146a8595SJ. Bruce Fields */ 4032146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 40331da177e4SLinus Torvalds { 40341da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 40358de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 40361da177e4SLinus Torvalds int error; 40371da177e4SLinus Torvalds 40381da177e4SLinus Torvalds if (!inode) 40391da177e4SLinus Torvalds return -ENOENT; 40401da177e4SLinus Torvalds 4041a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 40421da177e4SLinus Torvalds if (error) 40431da177e4SLinus Torvalds return error; 40441da177e4SLinus Torvalds 40451da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 40461da177e4SLinus Torvalds return -EXDEV; 40471da177e4SLinus Torvalds 40481da177e4SLinus Torvalds /* 40491da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 40501da177e4SLinus Torvalds */ 40511da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 40521da177e4SLinus Torvalds return -EPERM; 4053acfa4380SAl Viro if (!dir->i_op->link) 40541da177e4SLinus Torvalds return -EPERM; 40557e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 40561da177e4SLinus Torvalds return -EPERM; 40571da177e4SLinus Torvalds 40581da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 40591da177e4SLinus Torvalds if (error) 40601da177e4SLinus Torvalds return error; 40611da177e4SLinus Torvalds 40625955102cSAl Viro inode_lock(inode); 4063aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4064f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4065aae8a97dSAneesh Kumar K.V error = -ENOENT; 40668de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 40678de52778SAl Viro error = -EMLINK; 4068146a8595SJ. Bruce Fields else { 4069146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4070146a8595SJ. Bruce Fields if (!error) 40711da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4072146a8595SJ. Bruce Fields } 4073f4e0c30cSAl Viro 4074f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4075f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4076f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4077f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4078f4e0c30cSAl Viro } 40795955102cSAl Viro inode_unlock(inode); 4080e31e14ecSStephen Smalley if (!error) 40817e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 40821da177e4SLinus Torvalds return error; 40831da177e4SLinus Torvalds } 40844d359507SAl Viro EXPORT_SYMBOL(vfs_link); 40851da177e4SLinus Torvalds 40861da177e4SLinus Torvalds /* 40871da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 40881da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 40891da177e4SLinus Torvalds * newname. --KAB 40901da177e4SLinus Torvalds * 40911da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 40921da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 40931da177e4SLinus Torvalds * and other special files. --ADM 40941da177e4SLinus Torvalds */ 40952e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 40962e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 40971da177e4SLinus Torvalds { 40981da177e4SLinus Torvalds struct dentry *new_dentry; 4099dae6ad8fSAl Viro struct path old_path, new_path; 4100146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 410111a7b371SAneesh Kumar K.V int how = 0; 41021da177e4SLinus Torvalds int error; 41031da177e4SLinus Torvalds 410411a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4105c04030e1SUlrich Drepper return -EINVAL; 410611a7b371SAneesh Kumar K.V /* 4107f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4108f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4109f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 411011a7b371SAneesh Kumar K.V */ 4111f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4112f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4113f0cc6ffbSLinus Torvalds return -ENOENT; 411411a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4115f0cc6ffbSLinus Torvalds } 4116c04030e1SUlrich Drepper 411711a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 411811a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4119442e31caSJeff Layton retry: 412011a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 41211da177e4SLinus Torvalds if (error) 41222ad94ae6SAl Viro return error; 41232ad94ae6SAl Viro 4124442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4125442e31caSJeff Layton (how & LOOKUP_REVAL)); 41261da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 41276902d925SDave Hansen if (IS_ERR(new_dentry)) 4128dae6ad8fSAl Viro goto out; 4129dae6ad8fSAl Viro 4130dae6ad8fSAl Viro error = -EXDEV; 4131dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4132dae6ad8fSAl Viro goto out_dput; 4133800179c9SKees Cook error = may_linkat(&old_path); 4134800179c9SKees Cook if (unlikely(error)) 4135800179c9SKees Cook goto out_dput; 4136dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4137be6d3e56SKentaro Takeda if (error) 4138a8104a9fSAl Viro goto out_dput; 4139146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 414075c3f29dSDave Hansen out_dput: 4141921a1650SAl Viro done_path_create(&new_path, new_dentry); 4142146a8595SJ. Bruce Fields if (delegated_inode) { 4143146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4144d22e6338SOleg Drokin if (!error) { 4145d22e6338SOleg Drokin path_put(&old_path); 4146146a8595SJ. Bruce Fields goto retry; 4147146a8595SJ. Bruce Fields } 4148d22e6338SOleg Drokin } 4149442e31caSJeff Layton if (retry_estale(error, how)) { 4150d22e6338SOleg Drokin path_put(&old_path); 4151442e31caSJeff Layton how |= LOOKUP_REVAL; 4152442e31caSJeff Layton goto retry; 4153442e31caSJeff Layton } 41541da177e4SLinus Torvalds out: 41552d8f3038SAl Viro path_put(&old_path); 41561da177e4SLinus Torvalds 41571da177e4SLinus Torvalds return error; 41581da177e4SLinus Torvalds } 41591da177e4SLinus Torvalds 41603480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 41615590ff0dSUlrich Drepper { 4162c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 41635590ff0dSUlrich Drepper } 41645590ff0dSUlrich Drepper 4165bc27027aSMiklos Szeredi /** 4166bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4167bc27027aSMiklos Szeredi * @old_dir: parent of source 4168bc27027aSMiklos Szeredi * @old_dentry: source 4169bc27027aSMiklos Szeredi * @new_dir: parent of destination 4170bc27027aSMiklos Szeredi * @new_dentry: destination 4171bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4172520c8b16SMiklos Szeredi * @flags: rename flags 4173bc27027aSMiklos Szeredi * 4174bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4175bc27027aSMiklos Szeredi * 4176bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4177bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4178bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4179bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4180bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4181bc27027aSMiklos Szeredi * so. 4182bc27027aSMiklos Szeredi * 4183bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4184bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4185bc27027aSMiklos Szeredi * to be NFS exported. 4186bc27027aSMiklos Szeredi * 41871da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 41881da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 41891da177e4SLinus Torvalds * Problems: 4190d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 41911da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 41921da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4193a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 41941da177e4SLinus Torvalds * story. 41956cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 41966cedba89SJ. Bruce Fields * and source (if it is not a directory). 41971b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 41981da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 41991da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4200a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 42011da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 42021da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 42031da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4204a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 42051da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 42061da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 42071da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4208e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 42091b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 42101da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4211c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 42121da177e4SLinus Torvalds * locking]. 42131da177e4SLinus Torvalds */ 42141da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 42158e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4216520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 42171da177e4SLinus Torvalds { 42181da177e4SLinus Torvalds int error; 4219bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 422059b0df21SEric Paris const unsigned char *old_name; 4221bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4222bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4223da1ce067SMiklos Szeredi bool new_is_dir = false; 4224da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 42251da177e4SLinus Torvalds 4226bc27027aSMiklos Szeredi if (source == target) 42271da177e4SLinus Torvalds return 0; 42281da177e4SLinus Torvalds 42291da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 42301da177e4SLinus Torvalds if (error) 42311da177e4SLinus Torvalds return error; 42321da177e4SLinus Torvalds 4233da1ce067SMiklos Szeredi if (!target) { 4234a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4235da1ce067SMiklos Szeredi } else { 4236da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4237da1ce067SMiklos Szeredi 4238da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 42391da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4240da1ce067SMiklos Szeredi else 4241da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4242da1ce067SMiklos Szeredi } 42431da177e4SLinus Torvalds if (error) 42441da177e4SLinus Torvalds return error; 42451da177e4SLinus Torvalds 42467177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 42471da177e4SLinus Torvalds return -EPERM; 42481da177e4SLinus Torvalds 4249520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4250520c8b16SMiklos Szeredi return -EINVAL; 4251520c8b16SMiklos Szeredi 4252bc27027aSMiklos Szeredi /* 4253bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4254bc27027aSMiklos Szeredi * we'll need to flip '..'. 4255bc27027aSMiklos Szeredi */ 4256da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4257da1ce067SMiklos Szeredi if (is_dir) { 4258bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4259bc27027aSMiklos Szeredi if (error) 4260bc27027aSMiklos Szeredi return error; 4261bc27027aSMiklos Szeredi } 4262da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4263da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4264da1ce067SMiklos Szeredi if (error) 4265da1ce067SMiklos Szeredi return error; 4266da1ce067SMiklos Szeredi } 4267da1ce067SMiklos Szeredi } 42680eeca283SRobert Love 42690b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 42700b3974ebSMiklos Szeredi flags); 4271bc27027aSMiklos Szeredi if (error) 4272bc27027aSMiklos Szeredi return error; 4273bc27027aSMiklos Szeredi 4274bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4275bc27027aSMiklos Szeredi dget(new_dentry); 4276da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4277bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4278bc27027aSMiklos Szeredi else if (target) 42795955102cSAl Viro inode_lock(target); 4280bc27027aSMiklos Szeredi 4281bc27027aSMiklos Szeredi error = -EBUSY; 42827af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4283bc27027aSMiklos Szeredi goto out; 4284bc27027aSMiklos Szeredi 4285da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4286bc27027aSMiklos Szeredi error = -EMLINK; 4287da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4288bc27027aSMiklos Szeredi goto out; 4289da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4290da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4291da1ce067SMiklos Szeredi goto out; 4292da1ce067SMiklos Szeredi } 4293da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4294bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4295da1ce067SMiklos Szeredi if (!is_dir) { 4296bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4297bc27027aSMiklos Szeredi if (error) 4298bc27027aSMiklos Szeredi goto out; 4299da1ce067SMiklos Szeredi } 4300da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4301bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4302bc27027aSMiklos Szeredi if (error) 4303bc27027aSMiklos Szeredi goto out; 4304bc27027aSMiklos Szeredi } 43057177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4306520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4307520c8b16SMiklos Szeredi new_dir, new_dentry); 4308520c8b16SMiklos Szeredi } else { 43097177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4310520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4311520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4312520c8b16SMiklos Szeredi } 4313bc27027aSMiklos Szeredi if (error) 4314bc27027aSMiklos Szeredi goto out; 4315bc27027aSMiklos Szeredi 4316da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 43171da177e4SLinus Torvalds if (is_dir) 4318bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4319bc27027aSMiklos Szeredi dont_mount(new_dentry); 43208ed936b5SEric W. Biederman detach_mounts(new_dentry); 4321bc27027aSMiklos Szeredi } 4322da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4323da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4324bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4325da1ce067SMiklos Szeredi else 4326da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4327da1ce067SMiklos Szeredi } 4328bc27027aSMiklos Szeredi out: 4329da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4330bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4331bc27027aSMiklos Szeredi else if (target) 43325955102cSAl Viro inode_unlock(target); 4333bc27027aSMiklos Szeredi dput(new_dentry); 4334da1ce067SMiklos Szeredi if (!error) { 4335123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4336da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4337da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4338da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4339da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4340da1ce067SMiklos Szeredi } 4341da1ce067SMiklos Szeredi } 43420eeca283SRobert Love fsnotify_oldname_free(old_name); 43430eeca283SRobert Love 43441da177e4SLinus Torvalds return error; 43451da177e4SLinus Torvalds } 43464d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 43471da177e4SLinus Torvalds 4348520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4349520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 43501da177e4SLinus Torvalds { 43511da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 43521da177e4SLinus Torvalds struct dentry *trap; 4353f5beed75SAl Viro struct path old_path, new_path; 4354f5beed75SAl Viro struct qstr old_last, new_last; 4355f5beed75SAl Viro int old_type, new_type; 43568e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 435791a27b2aSJeff Layton struct filename *from; 435891a27b2aSJeff Layton struct filename *to; 4359f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4360c6a94284SJeff Layton bool should_retry = false; 43612ad94ae6SAl Viro int error; 4362520c8b16SMiklos Szeredi 43630d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4364da1ce067SMiklos Szeredi return -EINVAL; 4365da1ce067SMiklos Szeredi 43660d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 43670d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4368520c8b16SMiklos Szeredi return -EINVAL; 4369520c8b16SMiklos Szeredi 43700d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 43710d7a8555SMiklos Szeredi return -EPERM; 43720d7a8555SMiklos Szeredi 4373f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4374f5beed75SAl Viro target_flags = 0; 4375f5beed75SAl Viro 4376c6a94284SJeff Layton retry: 4377f5beed75SAl Viro from = user_path_parent(olddfd, oldname, 4378f5beed75SAl Viro &old_path, &old_last, &old_type, lookup_flags); 437991a27b2aSJeff Layton if (IS_ERR(from)) { 438091a27b2aSJeff Layton error = PTR_ERR(from); 43811da177e4SLinus Torvalds goto exit; 438291a27b2aSJeff Layton } 43831da177e4SLinus Torvalds 4384f5beed75SAl Viro to = user_path_parent(newdfd, newname, 4385f5beed75SAl Viro &new_path, &new_last, &new_type, lookup_flags); 438691a27b2aSJeff Layton if (IS_ERR(to)) { 438791a27b2aSJeff Layton error = PTR_ERR(to); 43881da177e4SLinus Torvalds goto exit1; 438991a27b2aSJeff Layton } 43901da177e4SLinus Torvalds 43911da177e4SLinus Torvalds error = -EXDEV; 4392f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 43931da177e4SLinus Torvalds goto exit2; 43941da177e4SLinus Torvalds 43951da177e4SLinus Torvalds error = -EBUSY; 4396f5beed75SAl Viro if (old_type != LAST_NORM) 43971da177e4SLinus Torvalds goto exit2; 43981da177e4SLinus Torvalds 43990a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 44000a7c3937SMiklos Szeredi error = -EEXIST; 4401f5beed75SAl Viro if (new_type != LAST_NORM) 44021da177e4SLinus Torvalds goto exit2; 44031da177e4SLinus Torvalds 4404f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4405c30dabfeSJan Kara if (error) 4406c30dabfeSJan Kara goto exit2; 4407c30dabfeSJan Kara 44088e6d782cSJ. Bruce Fields retry_deleg: 4409f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 44101da177e4SLinus Torvalds 4411f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 44121da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 44131da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 44141da177e4SLinus Torvalds goto exit3; 44151da177e4SLinus Torvalds /* source must exist */ 44161da177e4SLinus Torvalds error = -ENOENT; 4417b18825a7SDavid Howells if (d_is_negative(old_dentry)) 44181da177e4SLinus Torvalds goto exit4; 4419f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 44201da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 44211da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 44221da177e4SLinus Torvalds goto exit4; 44230a7c3937SMiklos Szeredi error = -EEXIST; 44240a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 44250a7c3937SMiklos Szeredi goto exit5; 4426da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4427da1ce067SMiklos Szeredi error = -ENOENT; 4428da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4429da1ce067SMiklos Szeredi goto exit5; 4430da1ce067SMiklos Szeredi 4431da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4432da1ce067SMiklos Szeredi error = -ENOTDIR; 4433f5beed75SAl Viro if (new_last.name[new_last.len]) 4434da1ce067SMiklos Szeredi goto exit5; 4435da1ce067SMiklos Szeredi } 4436da1ce067SMiklos Szeredi } 44370a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 44380a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 44390a7c3937SMiklos Szeredi error = -ENOTDIR; 4440f5beed75SAl Viro if (old_last.name[old_last.len]) 44410a7c3937SMiklos Szeredi goto exit5; 4442f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 44430a7c3937SMiklos Szeredi goto exit5; 44440a7c3937SMiklos Szeredi } 44450a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 44460a7c3937SMiklos Szeredi error = -EINVAL; 44470a7c3937SMiklos Szeredi if (old_dentry == trap) 44480a7c3937SMiklos Szeredi goto exit5; 44491da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4450da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 44511da177e4SLinus Torvalds error = -ENOTEMPTY; 44521da177e4SLinus Torvalds if (new_dentry == trap) 44531da177e4SLinus Torvalds goto exit5; 44541da177e4SLinus Torvalds 4455f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4456f5beed75SAl Viro &new_path, new_dentry, flags); 4457be6d3e56SKentaro Takeda if (error) 4458c30dabfeSJan Kara goto exit5; 4459f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4460f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4461520c8b16SMiklos Szeredi &delegated_inode, flags); 44621da177e4SLinus Torvalds exit5: 44631da177e4SLinus Torvalds dput(new_dentry); 44641da177e4SLinus Torvalds exit4: 44651da177e4SLinus Torvalds dput(old_dentry); 44661da177e4SLinus Torvalds exit3: 4467f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 44688e6d782cSJ. Bruce Fields if (delegated_inode) { 44698e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 44708e6d782cSJ. Bruce Fields if (!error) 44718e6d782cSJ. Bruce Fields goto retry_deleg; 44728e6d782cSJ. Bruce Fields } 4473f5beed75SAl Viro mnt_drop_write(old_path.mnt); 44741da177e4SLinus Torvalds exit2: 4475c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4476c6a94284SJeff Layton should_retry = true; 4477f5beed75SAl Viro path_put(&new_path); 44782ad94ae6SAl Viro putname(to); 44791da177e4SLinus Torvalds exit1: 4480f5beed75SAl Viro path_put(&old_path); 44811da177e4SLinus Torvalds putname(from); 4482c6a94284SJeff Layton if (should_retry) { 4483c6a94284SJeff Layton should_retry = false; 4484c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4485c6a94284SJeff Layton goto retry; 4486c6a94284SJeff Layton } 44872ad94ae6SAl Viro exit: 44881da177e4SLinus Torvalds return error; 44891da177e4SLinus Torvalds } 44901da177e4SLinus Torvalds 4491520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4492520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4493520c8b16SMiklos Szeredi { 4494520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4495520c8b16SMiklos Szeredi } 4496520c8b16SMiklos Szeredi 4497a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 44985590ff0dSUlrich Drepper { 4499520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 45005590ff0dSUlrich Drepper } 45015590ff0dSUlrich Drepper 4502787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4503787fb6bcSMiklos Szeredi { 4504787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4505787fb6bcSMiklos Szeredi if (error) 4506787fb6bcSMiklos Szeredi return error; 4507787fb6bcSMiklos Szeredi 4508787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4509787fb6bcSMiklos Szeredi return -EPERM; 4510787fb6bcSMiklos Szeredi 4511787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4512787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4513787fb6bcSMiklos Szeredi } 4514787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4515787fb6bcSMiklos Szeredi 45165d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 45171da177e4SLinus Torvalds { 45185d826c84SAl Viro int len = PTR_ERR(link); 45191da177e4SLinus Torvalds if (IS_ERR(link)) 45201da177e4SLinus Torvalds goto out; 45211da177e4SLinus Torvalds 45221da177e4SLinus Torvalds len = strlen(link); 45231da177e4SLinus Torvalds if (len > (unsigned) buflen) 45241da177e4SLinus Torvalds len = buflen; 45251da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 45261da177e4SLinus Torvalds len = -EFAULT; 45271da177e4SLinus Torvalds out: 45281da177e4SLinus Torvalds return len; 45291da177e4SLinus Torvalds } 45305d826c84SAl Viro EXPORT_SYMBOL(readlink_copy); 45311da177e4SLinus Torvalds 45321da177e4SLinus Torvalds /* 45331da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 45346b255391SAl Viro * have ->get_link() not calling nd_jump_link(). Using (or not using) it 45356b255391SAl Viro * for any given inode is up to filesystem. 45361da177e4SLinus Torvalds */ 45371da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 45381da177e4SLinus Torvalds { 4539fceef393SAl Viro DEFINE_DELAYED_CALL(done); 45405f2c4179SAl Viro struct inode *inode = d_inode(dentry); 45415f2c4179SAl Viro const char *link = inode->i_link; 4542694a1764SMarcin Slusarz int res; 4543cc314eefSLinus Torvalds 4544d4dee48bSAl Viro if (!link) { 4545fceef393SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4546680baacbSAl Viro if (IS_ERR(link)) 4547680baacbSAl Viro return PTR_ERR(link); 4548d4dee48bSAl Viro } 4549680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 4550fceef393SAl Viro do_delayed_call(&done); 4551694a1764SMarcin Slusarz return res; 45521da177e4SLinus Torvalds } 45534d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 45541da177e4SLinus Torvalds 45551da177e4SLinus Torvalds /* get the link contents into pagecache */ 45566b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4557fceef393SAl Viro struct delayed_call *callback) 45581da177e4SLinus Torvalds { 4559ebd09abbSDuane Griffin char *kaddr; 45601da177e4SLinus Torvalds struct page *page; 45616b255391SAl Viro struct address_space *mapping = inode->i_mapping; 45626b255391SAl Viro 4563d3883d4fSAl Viro if (!dentry) { 4564d3883d4fSAl Viro page = find_get_page(mapping, 0); 4565d3883d4fSAl Viro if (!page) 45666b255391SAl Viro return ERR_PTR(-ECHILD); 4567d3883d4fSAl Viro if (!PageUptodate(page)) { 4568d3883d4fSAl Viro put_page(page); 4569d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4570d3883d4fSAl Viro } 4571d3883d4fSAl Viro } else { 4572090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 45731da177e4SLinus Torvalds if (IS_ERR(page)) 45746fe6900eSNick Piggin return (char*)page; 4575d3883d4fSAl Viro } 4576fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 457721fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 457821fc61c7SAl Viro kaddr = page_address(page); 45796b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4580ebd09abbSDuane Griffin return kaddr; 45811da177e4SLinus Torvalds } 45821da177e4SLinus Torvalds 45836b255391SAl Viro EXPORT_SYMBOL(page_get_link); 45841da177e4SLinus Torvalds 4585fceef393SAl Viro void page_put_link(void *arg) 45861da177e4SLinus Torvalds { 4587fceef393SAl Viro put_page(arg); 45881da177e4SLinus Torvalds } 45894d359507SAl Viro EXPORT_SYMBOL(page_put_link); 45901da177e4SLinus Torvalds 4591aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4592aa80deabSAl Viro { 4593fceef393SAl Viro DEFINE_DELAYED_CALL(done); 45946b255391SAl Viro int res = readlink_copy(buffer, buflen, 45956b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4596fceef393SAl Viro &done)); 4597fceef393SAl Viro do_delayed_call(&done); 4598aa80deabSAl Viro return res; 4599aa80deabSAl Viro } 4600aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4601aa80deabSAl Viro 460254566b2cSNick Piggin /* 460354566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 460454566b2cSNick Piggin */ 460554566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 46061da177e4SLinus Torvalds { 46071da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 46080adb25d2SKirill Korotaev struct page *page; 4609afddba49SNick Piggin void *fsdata; 4610beb497abSDmitriy Monakhov int err; 461154566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 461254566b2cSNick Piggin if (nofs) 461354566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 46141da177e4SLinus Torvalds 46157e53cac4SNeilBrown retry: 4616afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 461754566b2cSNick Piggin flags, &page, &fsdata); 46181da177e4SLinus Torvalds if (err) 4619afddba49SNick Piggin goto fail; 4620afddba49SNick Piggin 462121fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4622afddba49SNick Piggin 4623afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4624afddba49SNick Piggin page, fsdata); 46251da177e4SLinus Torvalds if (err < 0) 46261da177e4SLinus Torvalds goto fail; 4627afddba49SNick Piggin if (err < len-1) 4628afddba49SNick Piggin goto retry; 4629afddba49SNick Piggin 46301da177e4SLinus Torvalds mark_inode_dirty(inode); 46311da177e4SLinus Torvalds return 0; 46321da177e4SLinus Torvalds fail: 46331da177e4SLinus Torvalds return err; 46341da177e4SLinus Torvalds } 46354d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 46361da177e4SLinus Torvalds 46370adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 46380adb25d2SKirill Korotaev { 46390adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4640c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 46410adb25d2SKirill Korotaev } 46424d359507SAl Viro EXPORT_SYMBOL(page_symlink); 46430adb25d2SKirill Korotaev 464492e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 46451da177e4SLinus Torvalds .readlink = generic_readlink, 46466b255391SAl Viro .get_link = page_get_link, 46471da177e4SLinus Torvalds }; 46481da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4649