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> 371da177e4SLinus Torvalds #include <asm/uaccess.h> 381da177e4SLinus Torvalds 39e81e3f4dSEric Paris #include "internal.h" 40c7105365SAl Viro #include "mount.h" 41e81e3f4dSEric Paris 421da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 431da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 441da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 451da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 461da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 471da177e4SLinus Torvalds * 481da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 491da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 501da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 511da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 521da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 531da177e4SLinus Torvalds * the special cases of the former code. 541da177e4SLinus Torvalds * 551da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 561da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 571da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 581da177e4SLinus Torvalds * 591da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 601da177e4SLinus Torvalds * resolution to correspond with current state of the code. 611da177e4SLinus Torvalds * 621da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 631da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 641da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 651da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 661da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 671da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 681da177e4SLinus Torvalds */ 691da177e4SLinus Torvalds 701da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 711da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 721da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 731da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 741da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 751da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7625985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 771da177e4SLinus Torvalds * 781da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 791da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 801da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 811da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 821da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 831da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 841da177e4SLinus Torvalds * and in the old Linux semantics. 851da177e4SLinus Torvalds */ 861da177e4SLinus Torvalds 871da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 881da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 891da177e4SLinus Torvalds * 901da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 911da177e4SLinus Torvalds */ 921da177e4SLinus Torvalds 931da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 941da177e4SLinus Torvalds * inside the path - always follow. 951da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 961da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 971da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 981da177e4SLinus Torvalds * otherwise - don't follow. 991da177e4SLinus Torvalds * (applied in that order). 1001da177e4SLinus Torvalds * 1011da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1021da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1031da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1041da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1051da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1061da177e4SLinus Torvalds */ 1071da177e4SLinus Torvalds /* 1081da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 109a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1101da177e4SLinus Torvalds * any extra contention... 1111da177e4SLinus Torvalds */ 1121da177e4SLinus Torvalds 1131da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1141da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1151da177e4SLinus Torvalds * kernel data space before using them.. 1161da177e4SLinus Torvalds * 1171da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1181da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1191da177e4SLinus Torvalds */ 12091a27b2aSJeff Layton void final_putname(struct filename *name) 1211da177e4SLinus Torvalds { 1227950e385SJeff Layton if (name->separate) { 12391a27b2aSJeff Layton __putname(name->name); 12491a27b2aSJeff Layton kfree(name); 1257950e385SJeff Layton } else { 1267950e385SJeff Layton __putname(name); 12791a27b2aSJeff Layton } 1287950e385SJeff Layton } 1297950e385SJeff Layton 1307950e385SJeff Layton #define EMBEDDED_NAME_MAX (PATH_MAX - sizeof(struct filename)) 13191a27b2aSJeff Layton 13291a27b2aSJeff Layton static struct filename * 13391a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 13491a27b2aSJeff Layton { 13591a27b2aSJeff Layton struct filename *result, *err; 1363f9f0aa6SLinus Torvalds int len; 1377950e385SJeff Layton long max; 1387950e385SJeff Layton char *kname; 1391da177e4SLinus Torvalds 1407ac86265SJeff Layton result = audit_reusename(filename); 1417ac86265SJeff Layton if (result) 1427ac86265SJeff Layton return result; 1437ac86265SJeff Layton 1447950e385SJeff Layton result = __getname(); 1453f9f0aa6SLinus Torvalds if (unlikely(!result)) 1464043cde8SEric Paris return ERR_PTR(-ENOMEM); 1471da177e4SLinus Torvalds 1487950e385SJeff Layton /* 1497950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1507950e385SJeff Layton * allocation 1517950e385SJeff Layton */ 1527950e385SJeff Layton kname = (char *)result + sizeof(*result); 15391a27b2aSJeff Layton result->name = kname; 1547950e385SJeff Layton result->separate = false; 1557950e385SJeff Layton max = EMBEDDED_NAME_MAX; 1567950e385SJeff Layton 1577950e385SJeff Layton recopy: 1587950e385SJeff Layton len = strncpy_from_user(kname, filename, max); 15991a27b2aSJeff Layton if (unlikely(len < 0)) { 1603f9f0aa6SLinus Torvalds err = ERR_PTR(len); 1613f9f0aa6SLinus Torvalds goto error; 16291a27b2aSJeff Layton } 1633f9f0aa6SLinus Torvalds 1647950e385SJeff Layton /* 1657950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1667950e385SJeff Layton * separate struct filename so we can dedicate the entire 1677950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1687950e385SJeff Layton * userland. 1697950e385SJeff Layton */ 1707950e385SJeff Layton if (len == EMBEDDED_NAME_MAX && max == EMBEDDED_NAME_MAX) { 1717950e385SJeff Layton kname = (char *)result; 1727950e385SJeff Layton 1737950e385SJeff Layton result = kzalloc(sizeof(*result), GFP_KERNEL); 1747950e385SJeff Layton if (!result) { 1757950e385SJeff Layton err = ERR_PTR(-ENOMEM); 1767950e385SJeff Layton result = (struct filename *)kname; 1777950e385SJeff Layton goto error; 1787950e385SJeff Layton } 1797950e385SJeff Layton result->name = kname; 1807950e385SJeff Layton result->separate = true; 1817950e385SJeff Layton max = PATH_MAX; 1827950e385SJeff Layton goto recopy; 1837950e385SJeff Layton } 1847950e385SJeff Layton 1853f9f0aa6SLinus Torvalds /* The empty path is special. */ 1863f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1873f9f0aa6SLinus Torvalds if (empty) 1881fa1e7f6SAndy Whitcroft *empty = 1; 1893f9f0aa6SLinus Torvalds err = ERR_PTR(-ENOENT); 1903f9f0aa6SLinus Torvalds if (!(flags & LOOKUP_EMPTY)) 1913f9f0aa6SLinus Torvalds goto error; 1921da177e4SLinus Torvalds } 1933f9f0aa6SLinus Torvalds 1943f9f0aa6SLinus Torvalds err = ERR_PTR(-ENAMETOOLONG); 1957950e385SJeff Layton if (unlikely(len >= PATH_MAX)) 1967950e385SJeff Layton goto error; 1977950e385SJeff Layton 1987950e385SJeff Layton result->uptr = filename; 1991da177e4SLinus Torvalds audit_getname(result); 2001da177e4SLinus Torvalds return result; 2011da177e4SLinus Torvalds 2023f9f0aa6SLinus Torvalds error: 2037950e385SJeff Layton final_putname(result); 2043f9f0aa6SLinus Torvalds return err; 2053f9f0aa6SLinus Torvalds } 2063f9f0aa6SLinus Torvalds 20791a27b2aSJeff Layton struct filename * 20891a27b2aSJeff Layton getname(const char __user * filename) 209f52e0c11SAl Viro { 210f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 211f52e0c11SAl Viro } 212f52e0c11SAl Viro 2131da177e4SLinus Torvalds #ifdef CONFIG_AUDITSYSCALL 21491a27b2aSJeff Layton void putname(struct filename *name) 2151da177e4SLinus Torvalds { 2165ac3a9c2SAl Viro if (unlikely(!audit_dummy_context())) 21791a27b2aSJeff Layton return audit_putname(name); 21891a27b2aSJeff Layton final_putname(name); 2191da177e4SLinus Torvalds } 2201da177e4SLinus Torvalds #endif 2211da177e4SLinus Torvalds 222e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 223e77819e5SLinus Torvalds { 22484635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 225e77819e5SLinus Torvalds struct posix_acl *acl; 226e77819e5SLinus Torvalds 227e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2283567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2293567866bSAl Viro if (!acl) 230e77819e5SLinus Torvalds return -EAGAIN; 2313567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 2323567866bSAl Viro if (acl == ACL_NOT_CACHED) 233e77819e5SLinus Torvalds return -ECHILD; 234206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 235e77819e5SLinus Torvalds } 236e77819e5SLinus Torvalds 2372982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2384e34e719SChristoph Hellwig if (IS_ERR(acl)) 2394e34e719SChristoph Hellwig return PTR_ERR(acl); 240e77819e5SLinus Torvalds if (acl) { 241e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 242e77819e5SLinus Torvalds posix_acl_release(acl); 243e77819e5SLinus Torvalds return error; 244e77819e5SLinus Torvalds } 24584635d68SLinus Torvalds #endif 246e77819e5SLinus Torvalds 247e77819e5SLinus Torvalds return -EAGAIN; 248e77819e5SLinus Torvalds } 249e77819e5SLinus Torvalds 2505909ccaaSLinus Torvalds /* 251948409c7SAndreas Gruenbacher * This does the basic permission checking 2525909ccaaSLinus Torvalds */ 2537e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2545909ccaaSLinus Torvalds { 25526cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2565909ccaaSLinus Torvalds 2578e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2585909ccaaSLinus Torvalds mode >>= 6; 2595909ccaaSLinus Torvalds else { 260e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2617e40145eSAl Viro int error = check_acl(inode, mask); 2625909ccaaSLinus Torvalds if (error != -EAGAIN) 2635909ccaaSLinus Torvalds return error; 2645909ccaaSLinus Torvalds } 2655909ccaaSLinus Torvalds 2665909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 2675909ccaaSLinus Torvalds mode >>= 3; 2685909ccaaSLinus Torvalds } 2695909ccaaSLinus Torvalds 2705909ccaaSLinus Torvalds /* 2715909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 2725909ccaaSLinus Torvalds */ 2739c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 2745909ccaaSLinus Torvalds return 0; 2755909ccaaSLinus Torvalds return -EACCES; 2765909ccaaSLinus Torvalds } 2771da177e4SLinus Torvalds 2781da177e4SLinus Torvalds /** 2791da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 2801da177e4SLinus Torvalds * @inode: inode to check access rights for 2818fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 2821da177e4SLinus Torvalds * 2831da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 2841da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 2851da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 286b74c79e9SNick Piggin * are used for other things. 287b74c79e9SNick Piggin * 288b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 289b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 290b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 2911da177e4SLinus Torvalds */ 2922830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 2931da177e4SLinus Torvalds { 2945909ccaaSLinus Torvalds int ret; 2951da177e4SLinus Torvalds 2961da177e4SLinus Torvalds /* 297948409c7SAndreas Gruenbacher * Do the basic permission checks. 2981da177e4SLinus Torvalds */ 2997e40145eSAl Viro ret = acl_permission_check(inode, mask); 3005909ccaaSLinus Torvalds if (ret != -EACCES) 3015909ccaaSLinus Torvalds return ret; 3021da177e4SLinus Torvalds 303d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 304d594e7ecSAl Viro /* DACs are overridable for directories */ 3051a48e2acSEric W. Biederman if (inode_capable(inode, CAP_DAC_OVERRIDE)) 306d594e7ecSAl Viro return 0; 307d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 3081a48e2acSEric W. Biederman if (inode_capable(inode, CAP_DAC_READ_SEARCH)) 309d594e7ecSAl Viro return 0; 310d594e7ecSAl Viro return -EACCES; 311d594e7ecSAl Viro } 3121da177e4SLinus Torvalds /* 3131da177e4SLinus Torvalds * Read/write DACs are always overridable. 314d594e7ecSAl Viro * Executable DACs are overridable when there is 315d594e7ecSAl Viro * at least one exec bit set. 3161da177e4SLinus Torvalds */ 317d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 3181a48e2acSEric W. Biederman if (inode_capable(inode, CAP_DAC_OVERRIDE)) 3191da177e4SLinus Torvalds return 0; 3201da177e4SLinus Torvalds 3211da177e4SLinus Torvalds /* 3221da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3231da177e4SLinus Torvalds */ 3247ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 325d594e7ecSAl Viro if (mask == MAY_READ) 3261a48e2acSEric W. Biederman if (inode_capable(inode, CAP_DAC_READ_SEARCH)) 3271da177e4SLinus Torvalds return 0; 3281da177e4SLinus Torvalds 3291da177e4SLinus Torvalds return -EACCES; 3301da177e4SLinus Torvalds } 3311da177e4SLinus Torvalds 3323ddcd056SLinus Torvalds /* 3333ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3343ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3353ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3363ddcd056SLinus Torvalds * permission function, use the fast case". 3373ddcd056SLinus Torvalds */ 3383ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3393ddcd056SLinus Torvalds { 3403ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3413ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3423ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3433ddcd056SLinus Torvalds 3443ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3453ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3463ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3473ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3483ddcd056SLinus Torvalds } 3493ddcd056SLinus Torvalds return generic_permission(inode, mask); 3503ddcd056SLinus Torvalds } 3513ddcd056SLinus Torvalds 352cb23beb5SChristoph Hellwig /** 3530bdaea90SDavid Howells * __inode_permission - Check for access rights to a given inode 3540bdaea90SDavid Howells * @inode: Inode to check permission on 3550bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 356cb23beb5SChristoph Hellwig * 3570bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. 358948409c7SAndreas Gruenbacher * 359948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 3600bdaea90SDavid Howells * 3610bdaea90SDavid Howells * This does not check for a read-only file system. You probably want 3620bdaea90SDavid Howells * inode_permission(). 363cb23beb5SChristoph Hellwig */ 3640bdaea90SDavid Howells int __inode_permission(struct inode *inode, int mask) 3651da177e4SLinus Torvalds { 366e6305c43SAl Viro int retval; 3671da177e4SLinus Torvalds 3683ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 3691da177e4SLinus Torvalds /* 3701da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 3711da177e4SLinus Torvalds */ 3721da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 3731da177e4SLinus Torvalds return -EACCES; 3741da177e4SLinus Torvalds } 3751da177e4SLinus Torvalds 3763ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 3771da177e4SLinus Torvalds if (retval) 3781da177e4SLinus Torvalds return retval; 3791da177e4SLinus Torvalds 38008ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 38108ce5f16SSerge E. Hallyn if (retval) 38208ce5f16SSerge E. Hallyn return retval; 38308ce5f16SSerge E. Hallyn 384d09ca739SEric Paris return security_inode_permission(inode, mask); 3851da177e4SLinus Torvalds } 3861da177e4SLinus Torvalds 387f4d6ff89SAl Viro /** 3880bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 3890bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 39055852635SRandy Dunlap * @inode: Inode to check permission on 3910bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 3920bdaea90SDavid Howells * 3930bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 3940bdaea90SDavid Howells */ 3950bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 3960bdaea90SDavid Howells { 3970bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 3980bdaea90SDavid Howells umode_t mode = inode->i_mode; 3990bdaea90SDavid Howells 4000bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 4010bdaea90SDavid Howells if ((sb->s_flags & MS_RDONLY) && 4020bdaea90SDavid Howells (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4030bdaea90SDavid Howells return -EROFS; 4040bdaea90SDavid Howells } 4050bdaea90SDavid Howells return 0; 4060bdaea90SDavid Howells } 4070bdaea90SDavid Howells 4080bdaea90SDavid Howells /** 4090bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4100bdaea90SDavid Howells * @inode: Inode to check permission on 4110bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4120bdaea90SDavid Howells * 4130bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4140bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4150bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4160bdaea90SDavid Howells * 4170bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4180bdaea90SDavid Howells */ 4190bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4200bdaea90SDavid Howells { 4210bdaea90SDavid Howells int retval; 4220bdaea90SDavid Howells 4230bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4240bdaea90SDavid Howells if (retval) 4250bdaea90SDavid Howells return retval; 4260bdaea90SDavid Howells return __inode_permission(inode, mask); 4270bdaea90SDavid Howells } 4280bdaea90SDavid Howells 4290bdaea90SDavid Howells /** 4305dd784d0SJan Blunck * path_get - get a reference to a path 4315dd784d0SJan Blunck * @path: path to get the reference to 4325dd784d0SJan Blunck * 4335dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4345dd784d0SJan Blunck */ 435dcf787f3SAl Viro void path_get(const struct path *path) 4365dd784d0SJan Blunck { 4375dd784d0SJan Blunck mntget(path->mnt); 4385dd784d0SJan Blunck dget(path->dentry); 4395dd784d0SJan Blunck } 4405dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4415dd784d0SJan Blunck 4425dd784d0SJan Blunck /** 4431d957f9bSJan Blunck * path_put - put a reference to a path 4441d957f9bSJan Blunck * @path: path to put the reference to 4451d957f9bSJan Blunck * 4461d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4471d957f9bSJan Blunck */ 448dcf787f3SAl Viro void path_put(const struct path *path) 4491da177e4SLinus Torvalds { 4501d957f9bSJan Blunck dput(path->dentry); 4511d957f9bSJan Blunck mntput(path->mnt); 4521da177e4SLinus Torvalds } 4531d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4541da177e4SLinus Torvalds 45519660af7SAl Viro /* 45631e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 45719660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 45819660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 45919660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 46019660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 46119660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 46219660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 46319660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 46431e6b01fSNick Piggin */ 46531e6b01fSNick Piggin 46631e6b01fSNick Piggin /** 46719660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 46819660af7SAl Viro * @nd: nameidata pathwalk data 46919660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 47039191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 47131e6b01fSNick Piggin * 47219660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 47319660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 47419660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 47531e6b01fSNick Piggin */ 47619660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 47731e6b01fSNick Piggin { 47831e6b01fSNick Piggin struct fs_struct *fs = current->fs; 47931e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 48031e6b01fSNick Piggin 48131e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 482e5c832d5SLinus Torvalds 483e5c832d5SLinus Torvalds /* 48448a066e7SAl Viro * After legitimizing the bastards, terminate_walk() 48548a066e7SAl Viro * will do the right thing for non-RCU mode, and all our 48648a066e7SAl Viro * subsequent exit cases should rcu_read_unlock() 48748a066e7SAl Viro * before returning. Do vfsmount first; if dentry 48848a066e7SAl Viro * can't be legitimized, just set nd->path.dentry to NULL 48948a066e7SAl Viro * and rely on dput(NULL) being a no-op. 490e5c832d5SLinus Torvalds */ 49148a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) 492e5c832d5SLinus Torvalds return -ECHILD; 493e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 49415570086SLinus Torvalds 49548a066e7SAl Viro if (!lockref_get_not_dead(&parent->d_lockref)) { 49648a066e7SAl Viro nd->path.dentry = NULL; 497d870b4a1SAl Viro goto out; 49848a066e7SAl Viro } 49948a066e7SAl Viro 50015570086SLinus Torvalds /* 50115570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 50215570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 50315570086SLinus Torvalds * 50415570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 50515570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 50615570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 50715570086SLinus Torvalds * since we checked the sequence number of the parent after we got 50815570086SLinus Torvalds * the child sequence number. So we know the parent must still 50915570086SLinus Torvalds * be valid if the child sequence number is still valid. 51015570086SLinus Torvalds */ 51119660af7SAl Viro if (!dentry) { 512e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 513e5c832d5SLinus Torvalds goto out; 51419660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 51519660af7SAl Viro } else { 516e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 517e5c832d5SLinus Torvalds goto out; 518e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) 519e5c832d5SLinus Torvalds goto drop_dentry; 52019660af7SAl Viro } 521e5c832d5SLinus Torvalds 522e5c832d5SLinus Torvalds /* 523e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 524e5c832d5SLinus Torvalds * still valid and get it if required. 525e5c832d5SLinus Torvalds */ 526e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 527e5c832d5SLinus Torvalds spin_lock(&fs->lock); 528e5c832d5SLinus Torvalds if (nd->root.mnt != fs->root.mnt || nd->root.dentry != fs->root.dentry) 529e5c832d5SLinus Torvalds goto unlock_and_drop_dentry; 53031e6b01fSNick Piggin path_get(&nd->root); 53131e6b01fSNick Piggin spin_unlock(&fs->lock); 53231e6b01fSNick Piggin } 53331e6b01fSNick Piggin 5348b61e74fSAl Viro rcu_read_unlock(); 53531e6b01fSNick Piggin return 0; 53619660af7SAl Viro 537e5c832d5SLinus Torvalds unlock_and_drop_dentry: 53831e6b01fSNick Piggin spin_unlock(&fs->lock); 539e5c832d5SLinus Torvalds drop_dentry: 5408b61e74fSAl Viro rcu_read_unlock(); 541e5c832d5SLinus Torvalds dput(dentry); 542d0d27277SLinus Torvalds goto drop_root_mnt; 543e5c832d5SLinus Torvalds out: 5448b61e74fSAl Viro rcu_read_unlock(); 545d0d27277SLinus Torvalds drop_root_mnt: 546d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 547d0d27277SLinus Torvalds nd->root.mnt = NULL; 54831e6b01fSNick Piggin return -ECHILD; 54931e6b01fSNick Piggin } 55031e6b01fSNick Piggin 5514ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 55234286d66SNick Piggin { 5534ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 55434286d66SNick Piggin } 55534286d66SNick Piggin 5569f1fafeeSAl Viro /** 5579f1fafeeSAl Viro * complete_walk - successful completion of path walk 5589f1fafeeSAl Viro * @nd: pointer nameidata 55939159de2SJeff Layton * 5609f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 5619f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 5629f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 5639f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 5649f1fafeeSAl Viro * need to drop nd->path. 56539159de2SJeff Layton */ 5669f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 56739159de2SJeff Layton { 56816c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 56939159de2SJeff Layton int status; 57039159de2SJeff Layton 5719f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 5729f1fafeeSAl Viro nd->flags &= ~LOOKUP_RCU; 5739f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 5749f1fafeeSAl Viro nd->root.mnt = NULL; 57515570086SLinus Torvalds 57648a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) { 5778b61e74fSAl Viro rcu_read_unlock(); 57848a066e7SAl Viro return -ECHILD; 57948a066e7SAl Viro } 580e5c832d5SLinus Torvalds if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) { 5818b61e74fSAl Viro rcu_read_unlock(); 58248a066e7SAl Viro mntput(nd->path.mnt); 5839f1fafeeSAl Viro return -ECHILD; 5849f1fafeeSAl Viro } 585e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) { 5868b61e74fSAl Viro rcu_read_unlock(); 587e5c832d5SLinus Torvalds dput(dentry); 58848a066e7SAl Viro mntput(nd->path.mnt); 589e5c832d5SLinus Torvalds return -ECHILD; 590e5c832d5SLinus Torvalds } 5918b61e74fSAl Viro rcu_read_unlock(); 5929f1fafeeSAl Viro } 5939f1fafeeSAl Viro 59416c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 59539159de2SJeff Layton return 0; 59639159de2SJeff Layton 597ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 59816c2cd71SAl Viro return 0; 59916c2cd71SAl Viro 600ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 60139159de2SJeff Layton if (status > 0) 60239159de2SJeff Layton return 0; 60339159de2SJeff Layton 60416c2cd71SAl Viro if (!status) 60539159de2SJeff Layton status = -ESTALE; 60616c2cd71SAl Viro 6079f1fafeeSAl Viro path_put(&nd->path); 60839159de2SJeff Layton return status; 60939159de2SJeff Layton } 61039159de2SJeff Layton 6112a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 6122a737871SAl Viro { 613f7ad3c6bSMiklos Szeredi if (!nd->root.mnt) 614f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 6152a737871SAl Viro } 6162a737871SAl Viro 6176de88d72SAl Viro static int link_path_walk(const char *, struct nameidata *); 6186de88d72SAl Viro 61931e6b01fSNick Piggin static __always_inline void set_root_rcu(struct nameidata *nd) 62031e6b01fSNick Piggin { 62131e6b01fSNick Piggin if (!nd->root.mnt) { 62231e6b01fSNick Piggin struct fs_struct *fs = current->fs; 623c28cc364SNick Piggin unsigned seq; 624c28cc364SNick Piggin 625c28cc364SNick Piggin do { 626c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 62731e6b01fSNick Piggin nd->root = fs->root; 628c1530019STim Chen nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 629c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 63031e6b01fSNick Piggin } 63131e6b01fSNick Piggin } 63231e6b01fSNick Piggin 6331d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 634051d3812SIan Kent { 635051d3812SIan Kent dput(path->dentry); 6364ac91378SJan Blunck if (path->mnt != nd->path.mnt) 637051d3812SIan Kent mntput(path->mnt); 638051d3812SIan Kent } 639051d3812SIan Kent 6407b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 6417b9337aaSNick Piggin struct nameidata *nd) 642051d3812SIan Kent { 64331e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 6444ac91378SJan Blunck dput(nd->path.dentry); 64531e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 6464ac91378SJan Blunck mntput(nd->path.mnt); 6479a229683SHuang Shijie } 64831e6b01fSNick Piggin nd->path.mnt = path->mnt; 6494ac91378SJan Blunck nd->path.dentry = path->dentry; 650051d3812SIan Kent } 651051d3812SIan Kent 652b5fb63c1SChristoph Hellwig /* 653b5fb63c1SChristoph Hellwig * Helper to directly jump to a known parsed path from ->follow_link, 654b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 655b5fb63c1SChristoph Hellwig */ 656b5fb63c1SChristoph Hellwig void nd_jump_link(struct nameidata *nd, struct path *path) 657b5fb63c1SChristoph Hellwig { 658b5fb63c1SChristoph Hellwig path_put(&nd->path); 659b5fb63c1SChristoph Hellwig 660b5fb63c1SChristoph Hellwig nd->path = *path; 661b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 662b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 663b5fb63c1SChristoph Hellwig } 664b5fb63c1SChristoph Hellwig 665574197e0SAl Viro static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) 666574197e0SAl Viro { 667574197e0SAl Viro struct inode *inode = link->dentry->d_inode; 6686d7b5aaeSAl Viro if (inode->i_op->put_link) 669574197e0SAl Viro inode->i_op->put_link(link->dentry, nd, cookie); 670574197e0SAl Viro path_put(link); 671574197e0SAl Viro } 672574197e0SAl Viro 673561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 674561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 675800179c9SKees Cook 676800179c9SKees Cook /** 677800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 678800179c9SKees Cook * @link: The path of the symlink 67955852635SRandy Dunlap * @nd: nameidata pathwalk data 680800179c9SKees Cook * 681800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 682800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 683800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 684800179c9SKees Cook * processes from failing races against path names that may change out 685800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 686800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 687800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 688800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 689800179c9SKees Cook * 690800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 691800179c9SKees Cook */ 692800179c9SKees Cook static inline int may_follow_link(struct path *link, struct nameidata *nd) 693800179c9SKees Cook { 694800179c9SKees Cook const struct inode *inode; 695800179c9SKees Cook const struct inode *parent; 696800179c9SKees Cook 697800179c9SKees Cook if (!sysctl_protected_symlinks) 698800179c9SKees Cook return 0; 699800179c9SKees Cook 700800179c9SKees Cook /* Allowed if owner and follower match. */ 701800179c9SKees Cook inode = link->dentry->d_inode; 70281abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 703800179c9SKees Cook return 0; 704800179c9SKees Cook 705800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 706800179c9SKees Cook parent = nd->path.dentry->d_inode; 707800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 708800179c9SKees Cook return 0; 709800179c9SKees Cook 710800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 71181abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 712800179c9SKees Cook return 0; 713800179c9SKees Cook 714ffd8d101SSasha Levin audit_log_link_denied("follow_link", link); 715800179c9SKees Cook path_put_conditional(link, nd); 716800179c9SKees Cook path_put(&nd->path); 717800179c9SKees Cook return -EACCES; 718800179c9SKees Cook } 719800179c9SKees Cook 720800179c9SKees Cook /** 721800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 722800179c9SKees Cook * @inode: the source inode to hardlink from 723800179c9SKees Cook * 724800179c9SKees Cook * Return false if at least one of the following conditions: 725800179c9SKees Cook * - inode is not a regular file 726800179c9SKees Cook * - inode is setuid 727800179c9SKees Cook * - inode is setgid and group-exec 728800179c9SKees Cook * - access failure for read and write 729800179c9SKees Cook * 730800179c9SKees Cook * Otherwise returns true. 731800179c9SKees Cook */ 732800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 733800179c9SKees Cook { 734800179c9SKees Cook umode_t mode = inode->i_mode; 735800179c9SKees Cook 736800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 737800179c9SKees Cook if (!S_ISREG(mode)) 738800179c9SKees Cook return false; 739800179c9SKees Cook 740800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 741800179c9SKees Cook if (mode & S_ISUID) 742800179c9SKees Cook return false; 743800179c9SKees Cook 744800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 745800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 746800179c9SKees Cook return false; 747800179c9SKees Cook 748800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 749800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 750800179c9SKees Cook return false; 751800179c9SKees Cook 752800179c9SKees Cook return true; 753800179c9SKees Cook } 754800179c9SKees Cook 755800179c9SKees Cook /** 756800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 757800179c9SKees Cook * @link: the source to hardlink from 758800179c9SKees Cook * 759800179c9SKees Cook * Block hardlink when all of: 760800179c9SKees Cook * - sysctl_protected_hardlinks enabled 761800179c9SKees Cook * - fsuid does not match inode 762800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 763800179c9SKees Cook * - not CAP_FOWNER 764800179c9SKees Cook * 765800179c9SKees Cook * Returns 0 if successful, -ve on error. 766800179c9SKees Cook */ 767800179c9SKees Cook static int may_linkat(struct path *link) 768800179c9SKees Cook { 769800179c9SKees Cook const struct cred *cred; 770800179c9SKees Cook struct inode *inode; 771800179c9SKees Cook 772800179c9SKees Cook if (!sysctl_protected_hardlinks) 773800179c9SKees Cook return 0; 774800179c9SKees Cook 775800179c9SKees Cook cred = current_cred(); 776800179c9SKees Cook inode = link->dentry->d_inode; 777800179c9SKees Cook 778800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 779800179c9SKees Cook * otherwise, it must be a safe source. 780800179c9SKees Cook */ 78181abe27bSEric W. Biederman if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || 782800179c9SKees Cook capable(CAP_FOWNER)) 783800179c9SKees Cook return 0; 784800179c9SKees Cook 785a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 786800179c9SKees Cook return -EPERM; 787800179c9SKees Cook } 788800179c9SKees Cook 789def4af30SAl Viro static __always_inline int 790574197e0SAl Viro follow_link(struct path *link, struct nameidata *nd, void **p) 7911da177e4SLinus Torvalds { 7927b9337aaSNick Piggin struct dentry *dentry = link->dentry; 7936d7b5aaeSAl Viro int error; 7946d7b5aaeSAl Viro char *s; 7951da177e4SLinus Torvalds 796844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 797844a3917SAl Viro 7980e794589SAl Viro if (link->mnt == nd->path.mnt) 7990e794589SAl Viro mntget(link->mnt); 8000e794589SAl Viro 8016d7b5aaeSAl Viro error = -ELOOP; 8026d7b5aaeSAl Viro if (unlikely(current->total_link_count >= 40)) 8036d7b5aaeSAl Viro goto out_put_nd_path; 8046d7b5aaeSAl Viro 805574197e0SAl Viro cond_resched(); 806574197e0SAl Viro current->total_link_count++; 807574197e0SAl Viro 80868ac1234SAl Viro touch_atime(link); 8091da177e4SLinus Torvalds nd_set_link(nd, NULL); 810cd4e91d3SAl Viro 81136f3b4f6SAl Viro error = security_inode_follow_link(link->dentry, nd); 8126d7b5aaeSAl Viro if (error) 8136d7b5aaeSAl Viro goto out_put_nd_path; 81436f3b4f6SAl Viro 81586acdca1SAl Viro nd->last_type = LAST_BIND; 816def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 817def4af30SAl Viro error = PTR_ERR(*p); 8186d7b5aaeSAl Viro if (IS_ERR(*p)) 819408ef013SChristoph Hellwig goto out_put_nd_path; 8206d7b5aaeSAl Viro 821cc314eefSLinus Torvalds error = 0; 8226d7b5aaeSAl Viro s = nd_get_link(nd); 8236d7b5aaeSAl Viro if (s) { 824443ed254SAl Viro if (unlikely(IS_ERR(s))) { 825443ed254SAl Viro path_put(&nd->path); 826443ed254SAl Viro put_link(nd, link, *p); 827443ed254SAl Viro return PTR_ERR(s); 828443ed254SAl Viro } 829443ed254SAl Viro if (*s == '/') { 830443ed254SAl Viro set_root(nd); 831443ed254SAl Viro path_put(&nd->path); 832443ed254SAl Viro nd->path = nd->root; 833443ed254SAl Viro path_get(&nd->root); 834443ed254SAl Viro nd->flags |= LOOKUP_JUMPED; 835443ed254SAl Viro } 836443ed254SAl Viro nd->inode = nd->path.dentry->d_inode; 837443ed254SAl Viro error = link_path_walk(s, nd); 8386d7b5aaeSAl Viro if (unlikely(error)) 8396d7b5aaeSAl Viro put_link(nd, link, *p); 840b5fb63c1SChristoph Hellwig } 8416d7b5aaeSAl Viro 8426d7b5aaeSAl Viro return error; 8436d7b5aaeSAl Viro 8446d7b5aaeSAl Viro out_put_nd_path: 84598f6ef64SArnd Bergmann *p = NULL; 8466d7b5aaeSAl Viro path_put(&nd->path); 8476d7b5aaeSAl Viro path_put(link); 8481da177e4SLinus Torvalds return error; 8491da177e4SLinus Torvalds } 8501da177e4SLinus Torvalds 85131e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 85231e6b01fSNick Piggin { 8530714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 8540714a533SAl Viro struct mount *parent; 85531e6b01fSNick Piggin struct dentry *mountpoint; 85631e6b01fSNick Piggin 8570714a533SAl Viro parent = mnt->mnt_parent; 8580714a533SAl Viro if (&parent->mnt == path->mnt) 85931e6b01fSNick Piggin return 0; 860a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 86131e6b01fSNick Piggin path->dentry = mountpoint; 8620714a533SAl Viro path->mnt = &parent->mnt; 86331e6b01fSNick Piggin return 1; 86431e6b01fSNick Piggin } 86531e6b01fSNick Piggin 866f015f126SDavid Howells /* 867f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 868f015f126SDavid Howells * 869f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 870f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 871f015f126SDavid Howells * Up is towards /. 872f015f126SDavid Howells * 873f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 874f015f126SDavid Howells * root. 875f015f126SDavid Howells */ 876bab77ebfSAl Viro int follow_up(struct path *path) 8771da177e4SLinus Torvalds { 8780714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 8790714a533SAl Viro struct mount *parent; 8801da177e4SLinus Torvalds struct dentry *mountpoint; 88199b7db7bSNick Piggin 88248a066e7SAl Viro read_seqlock_excl(&mount_lock); 8830714a533SAl Viro parent = mnt->mnt_parent; 8843c0a6163SAl Viro if (parent == mnt) { 88548a066e7SAl Viro read_sequnlock_excl(&mount_lock); 8861da177e4SLinus Torvalds return 0; 8871da177e4SLinus Torvalds } 8880714a533SAl Viro mntget(&parent->mnt); 889a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 89048a066e7SAl Viro read_sequnlock_excl(&mount_lock); 891bab77ebfSAl Viro dput(path->dentry); 892bab77ebfSAl Viro path->dentry = mountpoint; 893bab77ebfSAl Viro mntput(path->mnt); 8940714a533SAl Viro path->mnt = &parent->mnt; 8951da177e4SLinus Torvalds return 1; 8961da177e4SLinus Torvalds } 8971da177e4SLinus Torvalds 898b5c84bf6SNick Piggin /* 8999875cf80SDavid Howells * Perform an automount 9009875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 9019875cf80SDavid Howells * were called with. 9021da177e4SLinus Torvalds */ 9039875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 9049875cf80SDavid Howells bool *need_mntput) 90531e6b01fSNick Piggin { 9069875cf80SDavid Howells struct vfsmount *mnt; 907ea5b778aSDavid Howells int err; 9089875cf80SDavid Howells 9099875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 9109875cf80SDavid Howells return -EREMOTE; 9119875cf80SDavid Howells 9120ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 9130ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 9140ec26fd0SMiklos Szeredi * the name. 9150ec26fd0SMiklos Szeredi * 9160ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 9175a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 9180ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 9190ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 9200ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 9210ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 9225a30d8a2SDavid Howells */ 9235a30d8a2SDavid Howells if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 924d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 9255a30d8a2SDavid Howells path->dentry->d_inode) 9269875cf80SDavid Howells return -EISDIR; 9270ec26fd0SMiklos Szeredi 9289875cf80SDavid Howells current->total_link_count++; 9299875cf80SDavid Howells if (current->total_link_count >= 40) 9309875cf80SDavid Howells return -ELOOP; 9319875cf80SDavid Howells 9329875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 9339875cf80SDavid Howells if (IS_ERR(mnt)) { 9349875cf80SDavid Howells /* 9359875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 9369875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 9379875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 9389875cf80SDavid Howells * 9399875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 9409875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 9419875cf80SDavid Howells * the path is inaccessible and we should say so. 9429875cf80SDavid Howells */ 94349084c3bSAl Viro if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) 9449875cf80SDavid Howells return -EREMOTE; 9459875cf80SDavid Howells return PTR_ERR(mnt); 94631e6b01fSNick Piggin } 947ea5b778aSDavid Howells 9489875cf80SDavid Howells if (!mnt) /* mount collision */ 9499875cf80SDavid Howells return 0; 9509875cf80SDavid Howells 9518aef1884SAl Viro if (!*need_mntput) { 9528aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 9538aef1884SAl Viro mntget(path->mnt); 9548aef1884SAl Viro *need_mntput = true; 9558aef1884SAl Viro } 95619a167afSAl Viro err = finish_automount(mnt, path); 957ea5b778aSDavid Howells 958ea5b778aSDavid Howells switch (err) { 959ea5b778aSDavid Howells case -EBUSY: 960ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 96119a167afSAl Viro return 0; 962ea5b778aSDavid Howells case 0: 9638aef1884SAl Viro path_put(path); 9649875cf80SDavid Howells path->mnt = mnt; 9659875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 9669875cf80SDavid Howells return 0; 96719a167afSAl Viro default: 96819a167afSAl Viro return err; 9699875cf80SDavid Howells } 97019a167afSAl Viro 971ea5b778aSDavid Howells } 9729875cf80SDavid Howells 9739875cf80SDavid Howells /* 9749875cf80SDavid Howells * Handle a dentry that is managed in some way. 975cc53ce53SDavid Howells * - Flagged for transit management (autofs) 9769875cf80SDavid Howells * - Flagged as mountpoint 9779875cf80SDavid Howells * - Flagged as automount point 9789875cf80SDavid Howells * 9799875cf80SDavid Howells * This may only be called in refwalk mode. 9809875cf80SDavid Howells * 9819875cf80SDavid Howells * Serialization is taken care of in namespace.c 9829875cf80SDavid Howells */ 9839875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 9849875cf80SDavid Howells { 9858aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 9869875cf80SDavid Howells unsigned managed; 9879875cf80SDavid Howells bool need_mntput = false; 9888aef1884SAl Viro int ret = 0; 9899875cf80SDavid Howells 9909875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 9919875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 9929875cf80SDavid Howells * the components of that value change under us */ 9939875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 9949875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 9959875cf80SDavid Howells unlikely(managed != 0)) { 996cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 997cc53ce53SDavid Howells * being held. */ 998cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 999cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1000cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 10011aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1002cc53ce53SDavid Howells if (ret < 0) 10038aef1884SAl Viro break; 1004cc53ce53SDavid Howells } 1005cc53ce53SDavid Howells 10069875cf80SDavid Howells /* Transit to a mounted filesystem. */ 10079875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 10089875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10099875cf80SDavid Howells if (mounted) { 10109875cf80SDavid Howells dput(path->dentry); 10119875cf80SDavid Howells if (need_mntput) 1012463ffb2eSAl Viro mntput(path->mnt); 1013463ffb2eSAl Viro path->mnt = mounted; 1014463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 10159875cf80SDavid Howells need_mntput = true; 10169875cf80SDavid Howells continue; 1017463ffb2eSAl Viro } 1018463ffb2eSAl Viro 10199875cf80SDavid Howells /* Something is mounted on this dentry in another 10209875cf80SDavid Howells * namespace and/or whatever was mounted there in this 102148a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 102248a066e7SAl Viro * get it */ 10231da177e4SLinus Torvalds } 10249875cf80SDavid Howells 10259875cf80SDavid Howells /* Handle an automount point */ 10269875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 10279875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 10289875cf80SDavid Howells if (ret < 0) 10298aef1884SAl Viro break; 10309875cf80SDavid Howells continue; 10319875cf80SDavid Howells } 10329875cf80SDavid Howells 10339875cf80SDavid Howells /* We didn't change the current path point */ 10349875cf80SDavid Howells break; 10359875cf80SDavid Howells } 10368aef1884SAl Viro 10378aef1884SAl Viro if (need_mntput && path->mnt == mnt) 10388aef1884SAl Viro mntput(path->mnt); 10398aef1884SAl Viro if (ret == -EISDIR) 10408aef1884SAl Viro ret = 0; 1041a3fbbde7SAl Viro return ret < 0 ? ret : need_mntput; 10421da177e4SLinus Torvalds } 10431da177e4SLinus Torvalds 1044cc53ce53SDavid Howells int follow_down_one(struct path *path) 10451da177e4SLinus Torvalds { 10461da177e4SLinus Torvalds struct vfsmount *mounted; 10471da177e4SLinus Torvalds 10481c755af4SAl Viro mounted = lookup_mnt(path); 10491da177e4SLinus Torvalds if (mounted) { 10509393bd07SAl Viro dput(path->dentry); 10519393bd07SAl Viro mntput(path->mnt); 10529393bd07SAl Viro path->mnt = mounted; 10539393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 10541da177e4SLinus Torvalds return 1; 10551da177e4SLinus Torvalds } 10561da177e4SLinus Torvalds return 0; 10571da177e4SLinus Torvalds } 10581da177e4SLinus Torvalds 105962a7375eSIan Kent static inline bool managed_dentry_might_block(struct dentry *dentry) 106062a7375eSIan Kent { 106162a7375eSIan Kent return (dentry->d_flags & DCACHE_MANAGE_TRANSIT && 106262a7375eSIan Kent dentry->d_op->d_manage(dentry, true) < 0); 106362a7375eSIan Kent } 106462a7375eSIan Kent 10659875cf80SDavid Howells /* 1066287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1067287548e4SAl Viro * we meet a managed dentry that would need blocking. 10689875cf80SDavid Howells */ 10699875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1070287548e4SAl Viro struct inode **inode) 10719875cf80SDavid Howells { 107262a7375eSIan Kent for (;;) { 1073c7105365SAl Viro struct mount *mounted; 107462a7375eSIan Kent /* 107562a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 107662a7375eSIan Kent * that wants to block transit. 107762a7375eSIan Kent */ 1078287548e4SAl Viro if (unlikely(managed_dentry_might_block(path->dentry))) 1079ab90911fSDavid Howells return false; 108062a7375eSIan Kent 108162a7375eSIan Kent if (!d_mountpoint(path->dentry)) 108262a7375eSIan Kent break; 108362a7375eSIan Kent 1084474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 10859875cf80SDavid Howells if (!mounted) 10869875cf80SDavid Howells break; 1087c7105365SAl Viro path->mnt = &mounted->mnt; 1088c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1089a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 10909875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 109159430262SLinus Torvalds /* 109259430262SLinus Torvalds * Update the inode too. We don't need to re-check the 109359430262SLinus Torvalds * dentry sequence number here after this d_inode read, 109459430262SLinus Torvalds * because a mount-point is always pinned. 109559430262SLinus Torvalds */ 109659430262SLinus Torvalds *inode = path->dentry->d_inode; 10979875cf80SDavid Howells } 10989875cf80SDavid Howells return true; 10999875cf80SDavid Howells } 11009875cf80SDavid Howells 1101dea39376SAl Viro static void follow_mount_rcu(struct nameidata *nd) 1102287548e4SAl Viro { 1103dea39376SAl Viro while (d_mountpoint(nd->path.dentry)) { 1104c7105365SAl Viro struct mount *mounted; 1105474279dcSAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1106287548e4SAl Viro if (!mounted) 1107287548e4SAl Viro break; 1108c7105365SAl Viro nd->path.mnt = &mounted->mnt; 1109c7105365SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 1110dea39376SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1111287548e4SAl Viro } 1112287548e4SAl Viro } 1113287548e4SAl Viro 111431e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 111531e6b01fSNick Piggin { 111631e6b01fSNick Piggin set_root_rcu(nd); 111731e6b01fSNick Piggin 111831e6b01fSNick Piggin while (1) { 111931e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 112031e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 112131e6b01fSNick Piggin break; 112231e6b01fSNick Piggin } 112331e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 112431e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 112531e6b01fSNick Piggin struct dentry *parent = old->d_parent; 112631e6b01fSNick Piggin unsigned seq; 112731e6b01fSNick Piggin 112831e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 112931e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1130ef7562d5SAl Viro goto failed; 113131e6b01fSNick Piggin nd->path.dentry = parent; 113231e6b01fSNick Piggin nd->seq = seq; 113331e6b01fSNick Piggin break; 113431e6b01fSNick Piggin } 113531e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 113631e6b01fSNick Piggin break; 113731e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 113831e6b01fSNick Piggin } 1139dea39376SAl Viro follow_mount_rcu(nd); 1140dea39376SAl Viro nd->inode = nd->path.dentry->d_inode; 114131e6b01fSNick Piggin return 0; 1142ef7562d5SAl Viro 1143ef7562d5SAl Viro failed: 1144ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 11455b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1146ef7562d5SAl Viro nd->root.mnt = NULL; 11478b61e74fSAl Viro rcu_read_unlock(); 1148ef7562d5SAl Viro return -ECHILD; 114931e6b01fSNick Piggin } 115031e6b01fSNick Piggin 11519875cf80SDavid Howells /* 1152cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1153cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1154cc53ce53SDavid Howells * caller is permitted to proceed or not. 1155cc53ce53SDavid Howells */ 11567cc90cc3SAl Viro int follow_down(struct path *path) 1157cc53ce53SDavid Howells { 1158cc53ce53SDavid Howells unsigned managed; 1159cc53ce53SDavid Howells int ret; 1160cc53ce53SDavid Howells 1161cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1162cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1163cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1164cc53ce53SDavid Howells * being held. 1165cc53ce53SDavid Howells * 1166cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1167cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1168cc53ce53SDavid Howells * other than its daemon the right to mount on its 1169cc53ce53SDavid Howells * superstructure. 1170cc53ce53SDavid Howells * 1171cc53ce53SDavid Howells * The filesystem may sleep at this point. 1172cc53ce53SDavid Howells */ 1173cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1174cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1175cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1176ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 11771aed3e42SAl Viro path->dentry, false); 1178cc53ce53SDavid Howells if (ret < 0) 1179cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1180cc53ce53SDavid Howells } 1181cc53ce53SDavid Howells 1182cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1183cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1184cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1185cc53ce53SDavid Howells if (!mounted) 1186cc53ce53SDavid Howells break; 1187cc53ce53SDavid Howells dput(path->dentry); 1188cc53ce53SDavid Howells mntput(path->mnt); 1189cc53ce53SDavid Howells path->mnt = mounted; 1190cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1191cc53ce53SDavid Howells continue; 1192cc53ce53SDavid Howells } 1193cc53ce53SDavid Howells 1194cc53ce53SDavid Howells /* Don't handle automount points here */ 1195cc53ce53SDavid Howells break; 1196cc53ce53SDavid Howells } 1197cc53ce53SDavid Howells return 0; 1198cc53ce53SDavid Howells } 1199cc53ce53SDavid Howells 1200cc53ce53SDavid Howells /* 12019875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 12029875cf80SDavid Howells */ 12039875cf80SDavid Howells static void follow_mount(struct path *path) 12049875cf80SDavid Howells { 12059875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 12069875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12079875cf80SDavid Howells if (!mounted) 12089875cf80SDavid Howells break; 12099875cf80SDavid Howells dput(path->dentry); 12109875cf80SDavid Howells mntput(path->mnt); 12119875cf80SDavid Howells path->mnt = mounted; 12129875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 12139875cf80SDavid Howells } 12149875cf80SDavid Howells } 12159875cf80SDavid Howells 121631e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 12171da177e4SLinus Torvalds { 12182a737871SAl Viro set_root(nd); 1219e518ddb7SAndreas Mohr 12201da177e4SLinus Torvalds while(1) { 12214ac91378SJan Blunck struct dentry *old = nd->path.dentry; 12221da177e4SLinus Torvalds 12232a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 12242a737871SAl Viro nd->path.mnt == nd->root.mnt) { 12251da177e4SLinus Torvalds break; 12261da177e4SLinus Torvalds } 12274ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 12283088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 12293088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 12301da177e4SLinus Torvalds dput(old); 12311da177e4SLinus Torvalds break; 12321da177e4SLinus Torvalds } 12333088dd70SAl Viro if (!follow_up(&nd->path)) 12341da177e4SLinus Torvalds break; 12351da177e4SLinus Torvalds } 123679ed0226SAl Viro follow_mount(&nd->path); 123731e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 12381da177e4SLinus Torvalds } 12391da177e4SLinus Torvalds 12401da177e4SLinus Torvalds /* 1241bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1242bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1243bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1244bad61189SMiklos Szeredi * 1245bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1246baa03890SNick Piggin */ 1247bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1248201f956eSAl Viro unsigned int flags, bool *need_lookup) 1249baa03890SNick Piggin { 1250baa03890SNick Piggin struct dentry *dentry; 1251bad61189SMiklos Szeredi int error; 1252baa03890SNick Piggin 1253bad61189SMiklos Szeredi *need_lookup = false; 1254bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1255bad61189SMiklos Szeredi if (dentry) { 125639e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1257201f956eSAl Viro error = d_revalidate(dentry, flags); 1258bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1259bad61189SMiklos Szeredi if (error < 0) { 1260bad61189SMiklos Szeredi dput(dentry); 1261bad61189SMiklos Szeredi return ERR_PTR(error); 1262bad61189SMiklos Szeredi } else if (!d_invalidate(dentry)) { 1263bad61189SMiklos Szeredi dput(dentry); 1264bad61189SMiklos Szeredi dentry = NULL; 1265bad61189SMiklos Szeredi } 1266bad61189SMiklos Szeredi } 1267bad61189SMiklos Szeredi } 1268bad61189SMiklos Szeredi } 1269baa03890SNick Piggin 1270bad61189SMiklos Szeredi if (!dentry) { 1271bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1272baa03890SNick Piggin if (unlikely(!dentry)) 1273baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1274baa03890SNick Piggin 1275bad61189SMiklos Szeredi *need_lookup = true; 1276baa03890SNick Piggin } 1277baa03890SNick Piggin return dentry; 1278baa03890SNick Piggin } 1279baa03890SNick Piggin 1280baa03890SNick Piggin /* 128113a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 128213a2c3beSJ. Bruce Fields * unhashed. 1283bad61189SMiklos Szeredi * 1284bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 128544396f4bSJosef Bacik */ 1286bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 128772bd866aSAl Viro unsigned int flags) 128844396f4bSJosef Bacik { 128944396f4bSJosef Bacik struct dentry *old; 129044396f4bSJosef Bacik 129144396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1292bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1293e188dc02SMiklos Szeredi dput(dentry); 129444396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1295e188dc02SMiklos Szeredi } 129644396f4bSJosef Bacik 129772bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 129844396f4bSJosef Bacik if (unlikely(old)) { 129944396f4bSJosef Bacik dput(dentry); 130044396f4bSJosef Bacik dentry = old; 130144396f4bSJosef Bacik } 130244396f4bSJosef Bacik return dentry; 130344396f4bSJosef Bacik } 130444396f4bSJosef Bacik 1305a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 130672bd866aSAl Viro struct dentry *base, unsigned int flags) 1307a3255546SAl Viro { 1308bad61189SMiklos Szeredi bool need_lookup; 1309a3255546SAl Viro struct dentry *dentry; 1310a3255546SAl Viro 131172bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1312bad61189SMiklos Szeredi if (!need_lookup) 1313a3255546SAl Viro return dentry; 1314bad61189SMiklos Szeredi 131572bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1316a3255546SAl Viro } 1317a3255546SAl Viro 131844396f4bSJosef Bacik /* 13191da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 13201da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 13211da177e4SLinus Torvalds * It _is_ time-critical. 13221da177e4SLinus Torvalds */ 1323e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 132431e6b01fSNick Piggin struct path *path, struct inode **inode) 13251da177e4SLinus Torvalds { 13264ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 132731e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 13285a18fff2SAl Viro int need_reval = 1; 13295a18fff2SAl Viro int status = 1; 13309875cf80SDavid Howells int err; 13319875cf80SDavid Howells 13323cac260aSAl Viro /* 1333b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1334b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1335b04f784eSNick Piggin * do the non-racy lookup, below. 1336b04f784eSNick Piggin */ 133731e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 133831e6b01fSNick Piggin unsigned seq; 1339da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 13405a18fff2SAl Viro if (!dentry) 13415a18fff2SAl Viro goto unlazy; 13425a18fff2SAl Viro 134312f8ad4bSLinus Torvalds /* 134412f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 134512f8ad4bSLinus Torvalds * the dentry name information from lookup. 134612f8ad4bSLinus Torvalds */ 134712f8ad4bSLinus Torvalds *inode = dentry->d_inode; 134812f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 134912f8ad4bSLinus Torvalds return -ECHILD; 135012f8ad4bSLinus Torvalds 135112f8ad4bSLinus Torvalds /* 135212f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 135312f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 135412f8ad4bSLinus Torvalds * 135512f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 135612f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 135712f8ad4bSLinus Torvalds */ 135831e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 135931e6b01fSNick Piggin return -ECHILD; 136031e6b01fSNick Piggin nd->seq = seq; 13615a18fff2SAl Viro 136224643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 13634ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 13645a18fff2SAl Viro if (unlikely(status <= 0)) { 13655a18fff2SAl Viro if (status != -ECHILD) 13665a18fff2SAl Viro need_reval = 0; 13675a18fff2SAl Viro goto unlazy; 13685a18fff2SAl Viro } 136924643087SAl Viro } 137031e6b01fSNick Piggin path->mnt = mnt; 137131e6b01fSNick Piggin path->dentry = dentry; 1372d6e9bd25SAl Viro if (unlikely(!__follow_mount_rcu(nd, path, inode))) 1373d6e9bd25SAl Viro goto unlazy; 1374d6e9bd25SAl Viro if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) 1375d6e9bd25SAl Viro goto unlazy; 13769875cf80SDavid Howells return 0; 13775a18fff2SAl Viro unlazy: 137819660af7SAl Viro if (unlazy_walk(nd, dentry)) 13795a18fff2SAl Viro return -ECHILD; 13805a18fff2SAl Viro } else { 1381e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 138224643087SAl Viro } 13835a18fff2SAl Viro 138481e6f520SAl Viro if (unlikely(!dentry)) 138581e6f520SAl Viro goto need_lookup; 13865a18fff2SAl Viro 13875a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 13884ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 13895a18fff2SAl Viro if (unlikely(status <= 0)) { 13905a18fff2SAl Viro if (status < 0) { 13915a18fff2SAl Viro dput(dentry); 13925a18fff2SAl Viro return status; 13935a18fff2SAl Viro } 13945a18fff2SAl Viro if (!d_invalidate(dentry)) { 13955a18fff2SAl Viro dput(dentry); 139681e6f520SAl Viro goto need_lookup; 13975a18fff2SAl Viro } 13985a18fff2SAl Viro } 1399697f514dSMiklos Szeredi 14001da177e4SLinus Torvalds path->mnt = mnt; 14011da177e4SLinus Torvalds path->dentry = dentry; 14029875cf80SDavid Howells err = follow_managed(path, nd->flags); 140389312214SIan Kent if (unlikely(err < 0)) { 140489312214SIan Kent path_put_conditional(path, nd); 14059875cf80SDavid Howells return err; 140689312214SIan Kent } 1407a3fbbde7SAl Viro if (err) 1408a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 140931e6b01fSNick Piggin *inode = path->dentry->d_inode; 14101da177e4SLinus Torvalds return 0; 141181e6f520SAl Viro 141281e6f520SAl Viro need_lookup: 1413697f514dSMiklos Szeredi return 1; 1414697f514dSMiklos Szeredi } 1415697f514dSMiklos Szeredi 1416697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1417cc2a5271SAl Viro static int lookup_slow(struct nameidata *nd, struct path *path) 1418697f514dSMiklos Szeredi { 1419697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1420697f514dSMiklos Szeredi int err; 1421697f514dSMiklos Szeredi 1422697f514dSMiklos Szeredi parent = nd->path.dentry; 142381e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 142481e6f520SAl Viro 142581e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 1426cc2a5271SAl Viro dentry = __lookup_hash(&nd->last, parent, nd->flags); 142781e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 142881e6f520SAl Viro if (IS_ERR(dentry)) 142981e6f520SAl Viro return PTR_ERR(dentry); 1430697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1431697f514dSMiklos Szeredi path->dentry = dentry; 1432697f514dSMiklos Szeredi err = follow_managed(path, nd->flags); 1433697f514dSMiklos Szeredi if (unlikely(err < 0)) { 1434697f514dSMiklos Szeredi path_put_conditional(path, nd); 1435697f514dSMiklos Szeredi return err; 1436697f514dSMiklos Szeredi } 1437697f514dSMiklos Szeredi if (err) 1438697f514dSMiklos Szeredi nd->flags |= LOOKUP_JUMPED; 1439697f514dSMiklos Szeredi return 0; 14401da177e4SLinus Torvalds } 14411da177e4SLinus Torvalds 144252094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 144352094c8aSAl Viro { 144452094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 14454ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 144652094c8aSAl Viro if (err != -ECHILD) 144752094c8aSAl Viro return err; 144819660af7SAl Viro if (unlazy_walk(nd, NULL)) 144952094c8aSAl Viro return -ECHILD; 145052094c8aSAl Viro } 14514ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 145252094c8aSAl Viro } 145352094c8aSAl Viro 14549856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 14559856fa1bSAl Viro { 14569856fa1bSAl Viro if (type == LAST_DOTDOT) { 14579856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 14589856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 14599856fa1bSAl Viro return -ECHILD; 14609856fa1bSAl Viro } else 14619856fa1bSAl Viro follow_dotdot(nd); 14629856fa1bSAl Viro } 14639856fa1bSAl Viro return 0; 14649856fa1bSAl Viro } 14659856fa1bSAl Viro 1466951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1467951361f9SAl Viro { 1468951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1469951361f9SAl Viro path_put(&nd->path); 1470951361f9SAl Viro } else { 1471951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 14725b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1473951361f9SAl Viro nd->root.mnt = NULL; 14748b61e74fSAl Viro rcu_read_unlock(); 1475951361f9SAl Viro } 1476951361f9SAl Viro } 1477951361f9SAl Viro 14783ddcd056SLinus Torvalds /* 14793ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 14803ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 14813ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 14823ddcd056SLinus Torvalds * for the common case. 14833ddcd056SLinus Torvalds */ 1484b18825a7SDavid Howells static inline int should_follow_link(struct dentry *dentry, int follow) 14853ddcd056SLinus Torvalds { 1486b18825a7SDavid Howells return unlikely(d_is_symlink(dentry)) ? follow : 0; 14873ddcd056SLinus Torvalds } 14883ddcd056SLinus Torvalds 1489ce57dfc1SAl Viro static inline int walk_component(struct nameidata *nd, struct path *path, 149021b9b073SAl Viro int follow) 1491ce57dfc1SAl Viro { 1492ce57dfc1SAl Viro struct inode *inode; 1493ce57dfc1SAl Viro int err; 1494ce57dfc1SAl Viro /* 1495ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1496ce57dfc1SAl Viro * to be able to know about the current root directory and 1497ce57dfc1SAl Viro * parent relationships. 1498ce57dfc1SAl Viro */ 149921b9b073SAl Viro if (unlikely(nd->last_type != LAST_NORM)) 150021b9b073SAl Viro return handle_dots(nd, nd->last_type); 1501e97cdc87SAl Viro err = lookup_fast(nd, path, &inode); 1502ce57dfc1SAl Viro if (unlikely(err)) { 1503697f514dSMiklos Szeredi if (err < 0) 1504697f514dSMiklos Szeredi goto out_err; 1505697f514dSMiklos Szeredi 1506cc2a5271SAl Viro err = lookup_slow(nd, path); 1507697f514dSMiklos Szeredi if (err < 0) 1508697f514dSMiklos Szeredi goto out_err; 1509697f514dSMiklos Szeredi 1510697f514dSMiklos Szeredi inode = path->dentry->d_inode; 1511ce57dfc1SAl Viro } 1512697f514dSMiklos Szeredi err = -ENOENT; 1513697f514dSMiklos Szeredi if (!inode) 1514697f514dSMiklos Szeredi goto out_path_put; 1515697f514dSMiklos Szeredi 1516b18825a7SDavid Howells if (should_follow_link(path->dentry, follow)) { 151719660af7SAl Viro if (nd->flags & LOOKUP_RCU) { 151819660af7SAl Viro if (unlikely(unlazy_walk(nd, path->dentry))) { 1519697f514dSMiklos Szeredi err = -ECHILD; 1520697f514dSMiklos Szeredi goto out_err; 152119660af7SAl Viro } 152219660af7SAl Viro } 1523ce57dfc1SAl Viro BUG_ON(inode != path->dentry->d_inode); 1524ce57dfc1SAl Viro return 1; 1525ce57dfc1SAl Viro } 1526ce57dfc1SAl Viro path_to_nameidata(path, nd); 1527ce57dfc1SAl Viro nd->inode = inode; 1528ce57dfc1SAl Viro return 0; 1529697f514dSMiklos Szeredi 1530697f514dSMiklos Szeredi out_path_put: 1531697f514dSMiklos Szeredi path_to_nameidata(path, nd); 1532697f514dSMiklos Szeredi out_err: 1533697f514dSMiklos Szeredi terminate_walk(nd); 1534697f514dSMiklos Szeredi return err; 1535ce57dfc1SAl Viro } 1536ce57dfc1SAl Viro 15371da177e4SLinus Torvalds /* 1538b356379aSAl Viro * This limits recursive symlink follows to 8, while 1539b356379aSAl Viro * limiting consecutive symlinks to 40. 1540b356379aSAl Viro * 1541b356379aSAl Viro * Without that kind of total limit, nasty chains of consecutive 1542b356379aSAl Viro * symlinks can cause almost arbitrarily long lookups. 1543b356379aSAl Viro */ 1544b356379aSAl Viro static inline int nested_symlink(struct path *path, struct nameidata *nd) 1545b356379aSAl Viro { 1546b356379aSAl Viro int res; 1547b356379aSAl Viro 1548b356379aSAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 1549b356379aSAl Viro path_put_conditional(path, nd); 1550b356379aSAl Viro path_put(&nd->path); 1551b356379aSAl Viro return -ELOOP; 1552b356379aSAl Viro } 15531a4022f8SErez Zadok BUG_ON(nd->depth >= MAX_NESTED_LINKS); 1554b356379aSAl Viro 1555b356379aSAl Viro nd->depth++; 1556b356379aSAl Viro current->link_count++; 1557b356379aSAl Viro 1558b356379aSAl Viro do { 1559b356379aSAl Viro struct path link = *path; 1560b356379aSAl Viro void *cookie; 1561574197e0SAl Viro 1562574197e0SAl Viro res = follow_link(&link, nd, &cookie); 15636d7b5aaeSAl Viro if (res) 15646d7b5aaeSAl Viro break; 156521b9b073SAl Viro res = walk_component(nd, path, LOOKUP_FOLLOW); 1566574197e0SAl Viro put_link(nd, &link, cookie); 1567b356379aSAl Viro } while (res > 0); 1568b356379aSAl Viro 1569b356379aSAl Viro current->link_count--; 1570b356379aSAl Viro nd->depth--; 1571b356379aSAl Viro return res; 1572b356379aSAl Viro } 1573b356379aSAl Viro 1574b356379aSAl Viro /* 1575bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1576bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1577bfcfaa77SLinus Torvalds * 1578bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1579bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1580bfcfaa77SLinus Torvalds * fast. 1581bfcfaa77SLinus Torvalds * 1582bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1583bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1584bfcfaa77SLinus Torvalds * crossing operation. 1585bfcfaa77SLinus Torvalds * 1586bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1587bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1588bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1589bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1590bfcfaa77SLinus Torvalds */ 1591bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1592bfcfaa77SLinus Torvalds 1593f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1594bfcfaa77SLinus Torvalds 1595f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1596bfcfaa77SLinus Torvalds 1597bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1598bfcfaa77SLinus Torvalds { 1599bfcfaa77SLinus Torvalds hash += hash >> (8*sizeof(int)); 1600bfcfaa77SLinus Torvalds return hash; 1601bfcfaa77SLinus Torvalds } 1602bfcfaa77SLinus Torvalds 1603bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1604bfcfaa77SLinus Torvalds 1605bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1606bfcfaa77SLinus Torvalds 1607bfcfaa77SLinus Torvalds #endif 1608bfcfaa77SLinus Torvalds 1609bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1610bfcfaa77SLinus Torvalds { 1611bfcfaa77SLinus Torvalds unsigned long a, mask; 1612bfcfaa77SLinus Torvalds unsigned long hash = 0; 1613bfcfaa77SLinus Torvalds 1614bfcfaa77SLinus Torvalds for (;;) { 1615e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1616bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1617bfcfaa77SLinus Torvalds break; 1618bfcfaa77SLinus Torvalds hash += a; 1619f132c5beSAl Viro hash *= 9; 1620bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1621bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1622bfcfaa77SLinus Torvalds if (!len) 1623bfcfaa77SLinus Torvalds goto done; 1624bfcfaa77SLinus Torvalds } 1625a5c21dceSWill Deacon mask = bytemask_from_count(len); 1626bfcfaa77SLinus Torvalds hash += mask & a; 1627bfcfaa77SLinus Torvalds done: 1628bfcfaa77SLinus Torvalds return fold_hash(hash); 1629bfcfaa77SLinus Torvalds } 1630bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1631bfcfaa77SLinus Torvalds 1632bfcfaa77SLinus Torvalds /* 1633bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1634bfcfaa77SLinus Torvalds * return the length of the component; 1635bfcfaa77SLinus Torvalds */ 1636bfcfaa77SLinus Torvalds static inline unsigned long hash_name(const char *name, unsigned int *hashp) 1637bfcfaa77SLinus Torvalds { 163836126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 163936126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1640bfcfaa77SLinus Torvalds 1641bfcfaa77SLinus Torvalds hash = a = 0; 1642bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1643bfcfaa77SLinus Torvalds do { 1644bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1645bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1646e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 164736126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 164836126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1649bfcfaa77SLinus Torvalds 165036126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 165136126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 165236126f8fSLinus Torvalds 165336126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 165436126f8fSLinus Torvalds 165536126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 1656bfcfaa77SLinus Torvalds *hashp = fold_hash(hash); 1657bfcfaa77SLinus Torvalds 165836126f8fSLinus Torvalds return len + find_zero(mask); 1659bfcfaa77SLinus Torvalds } 1660bfcfaa77SLinus Torvalds 1661bfcfaa77SLinus Torvalds #else 1662bfcfaa77SLinus Torvalds 16630145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 16640145acc2SLinus Torvalds { 16650145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 16660145acc2SLinus Torvalds while (len--) 16670145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 16680145acc2SLinus Torvalds return end_name_hash(hash); 16690145acc2SLinus Torvalds } 1670ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 16710145acc2SLinus Torvalds 16723ddcd056SLinus Torvalds /* 1673200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1674200e9ef7SLinus Torvalds * one character. 1675200e9ef7SLinus Torvalds */ 1676200e9ef7SLinus Torvalds static inline unsigned long hash_name(const char *name, unsigned int *hashp) 1677200e9ef7SLinus Torvalds { 1678200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1679200e9ef7SLinus Torvalds unsigned long len = 0, c; 1680200e9ef7SLinus Torvalds 1681200e9ef7SLinus Torvalds c = (unsigned char)*name; 1682200e9ef7SLinus Torvalds do { 1683200e9ef7SLinus Torvalds len++; 1684200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1685200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1686200e9ef7SLinus Torvalds } while (c && c != '/'); 1687200e9ef7SLinus Torvalds *hashp = end_name_hash(hash); 1688200e9ef7SLinus Torvalds return len; 1689200e9ef7SLinus Torvalds } 1690200e9ef7SLinus Torvalds 1691bfcfaa77SLinus Torvalds #endif 1692bfcfaa77SLinus Torvalds 1693200e9ef7SLinus Torvalds /* 16941da177e4SLinus Torvalds * Name resolution. 1695ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1696ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 16971da177e4SLinus Torvalds * 1698ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1699ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 17001da177e4SLinus Torvalds */ 17016de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 17021da177e4SLinus Torvalds { 17031da177e4SLinus Torvalds struct path next; 17041da177e4SLinus Torvalds int err; 17051da177e4SLinus Torvalds 17061da177e4SLinus Torvalds while (*name=='/') 17071da177e4SLinus Torvalds name++; 17081da177e4SLinus Torvalds if (!*name) 1709086e183aSAl Viro return 0; 17101da177e4SLinus Torvalds 17111da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 17121da177e4SLinus Torvalds for(;;) { 17131da177e4SLinus Torvalds struct qstr this; 1714200e9ef7SLinus Torvalds long len; 1715fe479a58SAl Viro int type; 17161da177e4SLinus Torvalds 171752094c8aSAl Viro err = may_lookup(nd); 17181da177e4SLinus Torvalds if (err) 17191da177e4SLinus Torvalds break; 17201da177e4SLinus Torvalds 1721200e9ef7SLinus Torvalds len = hash_name(name, &this.hash); 17221da177e4SLinus Torvalds this.name = name; 1723200e9ef7SLinus Torvalds this.len = len; 17241da177e4SLinus Torvalds 1725fe479a58SAl Viro type = LAST_NORM; 1726200e9ef7SLinus Torvalds if (name[0] == '.') switch (len) { 1727fe479a58SAl Viro case 2: 1728200e9ef7SLinus Torvalds if (name[1] == '.') { 1729fe479a58SAl Viro type = LAST_DOTDOT; 173016c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 173116c2cd71SAl Viro } 1732fe479a58SAl Viro break; 1733fe479a58SAl Viro case 1: 1734fe479a58SAl Viro type = LAST_DOT; 1735fe479a58SAl Viro } 17365a202bcdSAl Viro if (likely(type == LAST_NORM)) { 17375a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 173816c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 17395a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 1740da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 17415a202bcdSAl Viro if (err < 0) 17425a202bcdSAl Viro break; 17435a202bcdSAl Viro } 17445a202bcdSAl Viro } 1745fe479a58SAl Viro 17465f4a6a69SAl Viro nd->last = this; 17475f4a6a69SAl Viro nd->last_type = type; 17485f4a6a69SAl Viro 1749200e9ef7SLinus Torvalds if (!name[len]) 17505f4a6a69SAl Viro return 0; 1751200e9ef7SLinus Torvalds /* 1752200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1753200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1754200e9ef7SLinus Torvalds */ 1755200e9ef7SLinus Torvalds do { 1756200e9ef7SLinus Torvalds len++; 1757200e9ef7SLinus Torvalds } while (unlikely(name[len] == '/')); 1758200e9ef7SLinus Torvalds if (!name[len]) 17595f4a6a69SAl Viro return 0; 17605f4a6a69SAl Viro 1761200e9ef7SLinus Torvalds name += len; 17621da177e4SLinus Torvalds 176321b9b073SAl Viro err = walk_component(nd, &next, LOOKUP_FOLLOW); 1764ce57dfc1SAl Viro if (err < 0) 1765ce57dfc1SAl Viro return err; 1766fe479a58SAl Viro 1767ce57dfc1SAl Viro if (err) { 1768b356379aSAl Viro err = nested_symlink(&next, nd); 17691da177e4SLinus Torvalds if (err) 1770a7472babSAl Viro return err; 177131e6b01fSNick Piggin } 1772b18825a7SDavid Howells if (!d_is_directory(nd->path.dentry)) { 17733ddcd056SLinus Torvalds err = -ENOTDIR; 17743ddcd056SLinus Torvalds break; 17755f4a6a69SAl Viro } 1776ce57dfc1SAl Viro } 1777951361f9SAl Viro terminate_walk(nd); 17781da177e4SLinus Torvalds return err; 17791da177e4SLinus Torvalds } 17801da177e4SLinus Torvalds 178170e9b357SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, 178270e9b357SAl Viro struct nameidata *nd, struct file **fp) 178331e6b01fSNick Piggin { 178431e6b01fSNick Piggin int retval = 0; 178531e6b01fSNick Piggin 178631e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 178716c2cd71SAl Viro nd->flags = flags | LOOKUP_JUMPED; 178831e6b01fSNick Piggin nd->depth = 0; 17895b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 1790b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 1791b18825a7SDavid Howells struct inode *inode = root->d_inode; 179273d049a4SAl Viro if (*name) { 1793b18825a7SDavid Howells if (!d_is_directory(root)) 17945b6ca027SAl Viro return -ENOTDIR; 17955b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 17965b6ca027SAl Viro if (retval) 17975b6ca027SAl Viro return retval; 179873d049a4SAl Viro } 17995b6ca027SAl Viro nd->path = nd->root; 18005b6ca027SAl Viro nd->inode = inode; 18015b6ca027SAl Viro if (flags & LOOKUP_RCU) { 18028b61e74fSAl Viro rcu_read_lock(); 18035b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 180448a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 18055b6ca027SAl Viro } else { 18065b6ca027SAl Viro path_get(&nd->path); 18075b6ca027SAl Viro } 18085b6ca027SAl Viro return 0; 18095b6ca027SAl Viro } 18105b6ca027SAl Viro 181131e6b01fSNick Piggin nd->root.mnt = NULL; 181231e6b01fSNick Piggin 181348a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 181431e6b01fSNick Piggin if (*name=='/') { 1815e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 18168b61e74fSAl Viro rcu_read_lock(); 1817e41f7d4eSAl Viro set_root_rcu(nd); 1818e41f7d4eSAl Viro } else { 1819e41f7d4eSAl Viro set_root(nd); 1820e41f7d4eSAl Viro path_get(&nd->root); 1821e41f7d4eSAl Viro } 182231e6b01fSNick Piggin nd->path = nd->root; 182331e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1824e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 182531e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1826c28cc364SNick Piggin unsigned seq; 182731e6b01fSNick Piggin 18288b61e74fSAl Viro rcu_read_lock(); 182931e6b01fSNick Piggin 1830c28cc364SNick Piggin do { 1831c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 183231e6b01fSNick Piggin nd->path = fs->pwd; 1833c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1834c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1835e41f7d4eSAl Viro } else { 1836e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1837e41f7d4eSAl Viro } 183831e6b01fSNick Piggin } else { 1839582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 18402903ff01SAl Viro struct fd f = fdget_raw(dfd); 184131e6b01fSNick Piggin struct dentry *dentry; 184231e6b01fSNick Piggin 18432903ff01SAl Viro if (!f.file) 18442903ff01SAl Viro return -EBADF; 184531e6b01fSNick Piggin 18462903ff01SAl Viro dentry = f.file->f_path.dentry; 184731e6b01fSNick Piggin 1848f52e0c11SAl Viro if (*name) { 1849b18825a7SDavid Howells if (!d_is_directory(dentry)) { 18502903ff01SAl Viro fdput(f); 18512903ff01SAl Viro return -ENOTDIR; 1852f52e0c11SAl Viro } 18532903ff01SAl Viro } 18542903ff01SAl Viro 18552903ff01SAl Viro nd->path = f.file->f_path; 1856e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 18572903ff01SAl Viro if (f.need_put) 18582903ff01SAl Viro *fp = f.file; 1859c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 18608b61e74fSAl Viro rcu_read_lock(); 18615590ff0dSUlrich Drepper } else { 18622903ff01SAl Viro path_get(&nd->path); 18632903ff01SAl Viro fdput(f); 18641da177e4SLinus Torvalds } 1865e41f7d4eSAl Viro } 1866e41f7d4eSAl Viro 186731e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 18689b4a9b14SAl Viro return 0; 18699b4a9b14SAl Viro } 18709b4a9b14SAl Viro 1871bd92d7feSAl Viro static inline int lookup_last(struct nameidata *nd, struct path *path) 1872bd92d7feSAl Viro { 1873bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1874bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1875bd92d7feSAl Viro 1876bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 187721b9b073SAl Viro return walk_component(nd, path, nd->flags & LOOKUP_FOLLOW); 1878bd92d7feSAl Viro } 1879bd92d7feSAl Viro 18809b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1881ee0827cdSAl Viro static int path_lookupat(int dfd, const char *name, 18829b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 18839b4a9b14SAl Viro { 188470e9b357SAl Viro struct file *base = NULL; 1885bd92d7feSAl Viro struct path path; 1886bd92d7feSAl Viro int err; 188731e6b01fSNick Piggin 188831e6b01fSNick Piggin /* 188931e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 189031e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 189131e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 189231e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 189331e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 189431e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 189531e6b01fSNick Piggin * analogue, foo_rcu(). 189631e6b01fSNick Piggin * 189731e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 189831e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 189931e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 190031e6b01fSNick Piggin * be able to complete). 190131e6b01fSNick Piggin */ 1902bd92d7feSAl Viro err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); 1903ee0827cdSAl Viro 1904bd92d7feSAl Viro if (unlikely(err)) 1905bd92d7feSAl Viro return err; 1906ee0827cdSAl Viro 1907ee0827cdSAl Viro current->total_link_count = 0; 1908bd92d7feSAl Viro err = link_path_walk(name, nd); 1909bd92d7feSAl Viro 1910bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 1911bd92d7feSAl Viro err = lookup_last(nd, &path); 1912bd92d7feSAl Viro while (err > 0) { 1913bd92d7feSAl Viro void *cookie; 1914bd92d7feSAl Viro struct path link = path; 1915800179c9SKees Cook err = may_follow_link(&link, nd); 1916800179c9SKees Cook if (unlikely(err)) 1917800179c9SKees Cook break; 1918bd92d7feSAl Viro nd->flags |= LOOKUP_PARENT; 1919574197e0SAl Viro err = follow_link(&link, nd, &cookie); 19206d7b5aaeSAl Viro if (err) 19216d7b5aaeSAl Viro break; 1922bd92d7feSAl Viro err = lookup_last(nd, &path); 1923574197e0SAl Viro put_link(nd, &link, cookie); 1924bd92d7feSAl Viro } 1925bd92d7feSAl Viro } 1926ee0827cdSAl Viro 19279f1fafeeSAl Viro if (!err) 19289f1fafeeSAl Viro err = complete_walk(nd); 1929bd92d7feSAl Viro 1930bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 1931b18825a7SDavid Howells if (!d_is_directory(nd->path.dentry)) { 1932bd92d7feSAl Viro path_put(&nd->path); 1933bd23a539SAl Viro err = -ENOTDIR; 1934bd92d7feSAl Viro } 1935bd92d7feSAl Viro } 193616c2cd71SAl Viro 193770e9b357SAl Viro if (base) 193870e9b357SAl Viro fput(base); 1939ee0827cdSAl Viro 19405b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 194131e6b01fSNick Piggin path_put(&nd->root); 194231e6b01fSNick Piggin nd->root.mnt = NULL; 194331e6b01fSNick Piggin } 1944bd92d7feSAl Viro return err; 194531e6b01fSNick Piggin } 194631e6b01fSNick Piggin 1947873f1eedSJeff Layton static int filename_lookup(int dfd, struct filename *name, 1948873f1eedSJeff Layton unsigned int flags, struct nameidata *nd) 1949873f1eedSJeff Layton { 1950873f1eedSJeff Layton int retval = path_lookupat(dfd, name->name, flags | LOOKUP_RCU, nd); 1951873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 1952873f1eedSJeff Layton retval = path_lookupat(dfd, name->name, flags, nd); 1953873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 1954873f1eedSJeff Layton retval = path_lookupat(dfd, name->name, 1955873f1eedSJeff Layton flags | LOOKUP_REVAL, nd); 1956873f1eedSJeff Layton 1957873f1eedSJeff Layton if (likely(!retval)) 1958adb5c247SJeff Layton audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); 1959873f1eedSJeff Layton return retval; 1960873f1eedSJeff Layton } 1961873f1eedSJeff Layton 1962ee0827cdSAl Viro static int do_path_lookup(int dfd, const char *name, 1963ee0827cdSAl Viro unsigned int flags, struct nameidata *nd) 1964ee0827cdSAl Viro { 1965873f1eedSJeff Layton struct filename filename = { .name = name }; 1966ee0827cdSAl Viro 1967873f1eedSJeff Layton return filename_lookup(dfd, &filename, flags, nd); 19681da177e4SLinus Torvalds } 19691da177e4SLinus Torvalds 197079714f72SAl Viro /* does lookup, returns the object with parent locked */ 197179714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 19725590ff0dSUlrich Drepper { 197379714f72SAl Viro struct nameidata nd; 197479714f72SAl Viro struct dentry *d; 197579714f72SAl Viro int err = do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, &nd); 197679714f72SAl Viro if (err) 197779714f72SAl Viro return ERR_PTR(err); 197879714f72SAl Viro if (nd.last_type != LAST_NORM) { 197979714f72SAl Viro path_put(&nd.path); 198079714f72SAl Viro return ERR_PTR(-EINVAL); 198179714f72SAl Viro } 198279714f72SAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 19831e0ea001SAl Viro d = __lookup_hash(&nd.last, nd.path.dentry, 0); 198479714f72SAl Viro if (IS_ERR(d)) { 198579714f72SAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 198679714f72SAl Viro path_put(&nd.path); 198779714f72SAl Viro return d; 198879714f72SAl Viro } 198979714f72SAl Viro *path = nd.path; 199079714f72SAl Viro return d; 19915590ff0dSUlrich Drepper } 19925590ff0dSUlrich Drepper 1993d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 1994d1811465SAl Viro { 1995d1811465SAl Viro struct nameidata nd; 1996d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 1997d1811465SAl Viro if (!res) 1998d1811465SAl Viro *path = nd.path; 1999d1811465SAl Viro return res; 2000d1811465SAl Viro } 2001d1811465SAl Viro 200216f18200SJosef 'Jeff' Sipek /** 200316f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 200416f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 200516f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 200616f18200SJosef 'Jeff' Sipek * @name: pointer to file name 200716f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2008e0a01249SAl Viro * @path: pointer to struct path to fill 200916f18200SJosef 'Jeff' Sipek */ 201016f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 201116f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2012e0a01249SAl Viro struct path *path) 201316f18200SJosef 'Jeff' Sipek { 2014e0a01249SAl Viro struct nameidata nd; 2015e0a01249SAl Viro int err; 2016e0a01249SAl Viro nd.root.dentry = dentry; 2017e0a01249SAl Viro nd.root.mnt = mnt; 2018e0a01249SAl Viro BUG_ON(flags & LOOKUP_PARENT); 20195b6ca027SAl Viro /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ 2020e0a01249SAl Viro err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd); 2021e0a01249SAl Viro if (!err) 2022e0a01249SAl Viro *path = nd.path; 2023e0a01249SAl Viro return err; 202416f18200SJosef 'Jeff' Sipek } 202516f18200SJosef 'Jeff' Sipek 2026057f6c01SJames Morris /* 2027057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 2028057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 2029057f6c01SJames Morris * SMP-safe. 2030057f6c01SJames Morris */ 2031a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 20321da177e4SLinus Torvalds { 203372bd866aSAl Viro return __lookup_hash(&nd->last, nd->path.dentry, nd->flags); 20341da177e4SLinus Torvalds } 20351da177e4SLinus Torvalds 2036eead1911SChristoph Hellwig /** 2037a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2038eead1911SChristoph Hellwig * @name: pathname component to lookup 2039eead1911SChristoph Hellwig * @base: base directory to lookup from 2040eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2041eead1911SChristoph Hellwig * 2042a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 2043a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 2044eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 2045eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 2046eead1911SChristoph Hellwig */ 2047057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2048057f6c01SJames Morris { 2049057f6c01SJames Morris struct qstr this; 20506a96ba54SAl Viro unsigned int c; 2051cda309deSMiklos Szeredi int err; 2052057f6c01SJames Morris 20532f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 20542f9092e1SDavid Woodhouse 20556a96ba54SAl Viro this.name = name; 20566a96ba54SAl Viro this.len = len; 20570145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 20586a96ba54SAl Viro if (!len) 20596a96ba54SAl Viro return ERR_PTR(-EACCES); 20606a96ba54SAl Viro 206121d8a15aSAl Viro if (unlikely(name[0] == '.')) { 206221d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 206321d8a15aSAl Viro return ERR_PTR(-EACCES); 206421d8a15aSAl Viro } 206521d8a15aSAl Viro 20666a96ba54SAl Viro while (len--) { 20676a96ba54SAl Viro c = *(const unsigned char *)name++; 20686a96ba54SAl Viro if (c == '/' || c == '\0') 20696a96ba54SAl Viro return ERR_PTR(-EACCES); 20706a96ba54SAl Viro } 20715a202bcdSAl Viro /* 20725a202bcdSAl Viro * See if the low-level filesystem might want 20735a202bcdSAl Viro * to use its own hash.. 20745a202bcdSAl Viro */ 20755a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2076da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 20775a202bcdSAl Viro if (err < 0) 20785a202bcdSAl Viro return ERR_PTR(err); 20795a202bcdSAl Viro } 2080eead1911SChristoph Hellwig 2081cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2082cda309deSMiklos Szeredi if (err) 2083cda309deSMiklos Szeredi return ERR_PTR(err); 2084cda309deSMiklos Szeredi 208572bd866aSAl Viro return __lookup_hash(&this, base, 0); 2086057f6c01SJames Morris } 2087057f6c01SJames Morris 20881fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 20891fa1e7f6SAndy Whitcroft struct path *path, int *empty) 20901da177e4SLinus Torvalds { 20912d8f3038SAl Viro struct nameidata nd; 209291a27b2aSJeff Layton struct filename *tmp = getname_flags(name, flags, empty); 20931da177e4SLinus Torvalds int err = PTR_ERR(tmp); 20941da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 20952d8f3038SAl Viro 20962d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 20972d8f3038SAl Viro 2098873f1eedSJeff Layton err = filename_lookup(dfd, tmp, flags, &nd); 20991da177e4SLinus Torvalds putname(tmp); 21002d8f3038SAl Viro if (!err) 21012d8f3038SAl Viro *path = nd.path; 21021da177e4SLinus Torvalds } 21031da177e4SLinus Torvalds return err; 21041da177e4SLinus Torvalds } 21051da177e4SLinus Torvalds 21061fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 21071fa1e7f6SAndy Whitcroft struct path *path) 21081fa1e7f6SAndy Whitcroft { 2109f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 21101fa1e7f6SAndy Whitcroft } 21111fa1e7f6SAndy Whitcroft 2112873f1eedSJeff Layton /* 2113873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2114873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2115873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2116873f1eedSJeff Layton * path-walking is complete. 2117873f1eedSJeff Layton */ 211891a27b2aSJeff Layton static struct filename * 21199e790bd6SJeff Layton user_path_parent(int dfd, const char __user *path, struct nameidata *nd, 21209e790bd6SJeff Layton unsigned int flags) 21212ad94ae6SAl Viro { 212291a27b2aSJeff Layton struct filename *s = getname(path); 21232ad94ae6SAl Viro int error; 21242ad94ae6SAl Viro 21259e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 21269e790bd6SJeff Layton flags &= LOOKUP_REVAL; 21279e790bd6SJeff Layton 21282ad94ae6SAl Viro if (IS_ERR(s)) 212991a27b2aSJeff Layton return s; 21302ad94ae6SAl Viro 21319e790bd6SJeff Layton error = filename_lookup(dfd, s, flags | LOOKUP_PARENT, nd); 213291a27b2aSJeff Layton if (error) { 21332ad94ae6SAl Viro putname(s); 213491a27b2aSJeff Layton return ERR_PTR(error); 213591a27b2aSJeff Layton } 21362ad94ae6SAl Viro 213791a27b2aSJeff Layton return s; 21382ad94ae6SAl Viro } 21392ad94ae6SAl Viro 21408033426eSJeff Layton /** 2141197df04cSAl Viro * mountpoint_last - look up last component for umount 21428033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 21438033426eSJeff Layton * @path: pointer to container for result 21448033426eSJeff Layton * 21458033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 21468033426eSJeff Layton * need to resolve the path without doing any revalidation. 21478033426eSJeff Layton * 21488033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 21498033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 21508033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 21518033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 21528033426eSJeff Layton * bogus and it doesn't exist. 21538033426eSJeff Layton * 21548033426eSJeff Layton * Returns: 21558033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 21568033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 21578033426eSJeff Layton * put in this case. 21588033426eSJeff Layton * 21598033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 21608033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 21618033426eSJeff Layton * The nd->path reference will also be put. 21628033426eSJeff Layton * 21638033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 21648033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 21658033426eSJeff Layton * to the link, and nd->path will *not* be put. 21668033426eSJeff Layton */ 21678033426eSJeff Layton static int 2168197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 21698033426eSJeff Layton { 21708033426eSJeff Layton int error = 0; 21718033426eSJeff Layton struct dentry *dentry; 21728033426eSJeff Layton struct dentry *dir = nd->path.dentry; 21738033426eSJeff Layton 217435759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 217535759521SAl Viro if (nd->flags & LOOKUP_RCU) { 217635759521SAl Viro if (unlazy_walk(nd, NULL)) { 21778033426eSJeff Layton error = -ECHILD; 217835759521SAl Viro goto out; 217935759521SAl Viro } 21808033426eSJeff Layton } 21818033426eSJeff Layton 21828033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 21838033426eSJeff Layton 21848033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 21858033426eSJeff Layton error = handle_dots(nd, nd->last_type); 218635759521SAl Viro if (error) 218735759521SAl Viro goto out; 21888033426eSJeff Layton dentry = dget(nd->path.dentry); 218935759521SAl Viro goto done; 21908033426eSJeff Layton } 21918033426eSJeff Layton 21928033426eSJeff Layton mutex_lock(&dir->d_inode->i_mutex); 21938033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 21948033426eSJeff Layton if (!dentry) { 21958033426eSJeff Layton /* 21968033426eSJeff Layton * No cached dentry. Mounted dentries are pinned in the cache, 21978033426eSJeff Layton * so that means that this dentry is probably a symlink or the 21988033426eSJeff Layton * path doesn't actually point to a mounted dentry. 21998033426eSJeff Layton */ 22008033426eSJeff Layton dentry = d_alloc(dir, &nd->last); 22018033426eSJeff Layton if (!dentry) { 22028033426eSJeff Layton error = -ENOMEM; 2203bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 220435759521SAl Viro goto out; 22058033426eSJeff Layton } 220635759521SAl Viro dentry = lookup_real(dir->d_inode, dentry, nd->flags); 220735759521SAl Viro error = PTR_ERR(dentry); 2208bcceeebaSDave Jones if (IS_ERR(dentry)) { 2209bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 221035759521SAl Viro goto out; 22118033426eSJeff Layton } 2212bcceeebaSDave Jones } 22138033426eSJeff Layton mutex_unlock(&dir->d_inode->i_mutex); 22148033426eSJeff Layton 221535759521SAl Viro done: 22168033426eSJeff Layton if (!dentry->d_inode) { 22178033426eSJeff Layton error = -ENOENT; 22188033426eSJeff Layton dput(dentry); 221935759521SAl Viro goto out; 222035759521SAl Viro } 22218033426eSJeff Layton path->dentry = dentry; 22228033426eSJeff Layton path->mnt = mntget(nd->path.mnt); 2223b18825a7SDavid Howells if (should_follow_link(dentry, nd->flags & LOOKUP_FOLLOW)) 22248033426eSJeff Layton return 1; 22258033426eSJeff Layton follow_mount(path); 222635759521SAl Viro error = 0; 222735759521SAl Viro out: 22288033426eSJeff Layton terminate_walk(nd); 22298033426eSJeff Layton return error; 22308033426eSJeff Layton } 22318033426eSJeff Layton 22328033426eSJeff Layton /** 2233197df04cSAl Viro * path_mountpoint - look up a path to be umounted 22348033426eSJeff Layton * @dfd: directory file descriptor to start walk from 22358033426eSJeff Layton * @name: full pathname to walk 2236606d6fe3SRandy Dunlap * @path: pointer to container for result 22378033426eSJeff Layton * @flags: lookup flags 22388033426eSJeff Layton * 22398033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2240606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 22418033426eSJeff Layton */ 22428033426eSJeff Layton static int 2243197df04cSAl Viro path_mountpoint(int dfd, const char *name, struct path *path, unsigned int flags) 22448033426eSJeff Layton { 22458033426eSJeff Layton struct file *base = NULL; 22468033426eSJeff Layton struct nameidata nd; 22478033426eSJeff Layton int err; 22488033426eSJeff Layton 22498033426eSJeff Layton err = path_init(dfd, name, flags | LOOKUP_PARENT, &nd, &base); 22508033426eSJeff Layton if (unlikely(err)) 22518033426eSJeff Layton return err; 22528033426eSJeff Layton 22538033426eSJeff Layton current->total_link_count = 0; 22548033426eSJeff Layton err = link_path_walk(name, &nd); 22558033426eSJeff Layton if (err) 22568033426eSJeff Layton goto out; 22578033426eSJeff Layton 2258197df04cSAl Viro err = mountpoint_last(&nd, path); 22598033426eSJeff Layton while (err > 0) { 22608033426eSJeff Layton void *cookie; 22618033426eSJeff Layton struct path link = *path; 22628033426eSJeff Layton err = may_follow_link(&link, &nd); 22638033426eSJeff Layton if (unlikely(err)) 22648033426eSJeff Layton break; 22658033426eSJeff Layton nd.flags |= LOOKUP_PARENT; 22668033426eSJeff Layton err = follow_link(&link, &nd, &cookie); 22678033426eSJeff Layton if (err) 22688033426eSJeff Layton break; 2269197df04cSAl Viro err = mountpoint_last(&nd, path); 22708033426eSJeff Layton put_link(&nd, &link, cookie); 22718033426eSJeff Layton } 22728033426eSJeff Layton out: 22738033426eSJeff Layton if (base) 22748033426eSJeff Layton fput(base); 22758033426eSJeff Layton 22768033426eSJeff Layton if (nd.root.mnt && !(nd.flags & LOOKUP_ROOT)) 22778033426eSJeff Layton path_put(&nd.root); 22788033426eSJeff Layton 22798033426eSJeff Layton return err; 22808033426eSJeff Layton } 22818033426eSJeff Layton 22822d864651SAl Viro static int 22832d864651SAl Viro filename_mountpoint(int dfd, struct filename *s, struct path *path, 22842d864651SAl Viro unsigned int flags) 22852d864651SAl Viro { 22862d864651SAl Viro int error = path_mountpoint(dfd, s->name, path, flags | LOOKUP_RCU); 22872d864651SAl Viro if (unlikely(error == -ECHILD)) 22882d864651SAl Viro error = path_mountpoint(dfd, s->name, path, flags); 22892d864651SAl Viro if (unlikely(error == -ESTALE)) 22902d864651SAl Viro error = path_mountpoint(dfd, s->name, path, flags | LOOKUP_REVAL); 22912d864651SAl Viro if (likely(!error)) 22922d864651SAl Viro audit_inode(s, path->dentry, 0); 22932d864651SAl Viro return error; 22942d864651SAl Viro } 22952d864651SAl Viro 22968033426eSJeff Layton /** 2297197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 22988033426eSJeff Layton * @dfd: directory file descriptor 22998033426eSJeff Layton * @name: pathname from userland 23008033426eSJeff Layton * @flags: lookup flags 23018033426eSJeff Layton * @path: pointer to container to hold result 23028033426eSJeff Layton * 23038033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 23048033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 23058033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 23068033426eSJeff Layton * and avoid revalidating the last component. 23078033426eSJeff Layton * 23088033426eSJeff Layton * Returns 0 and populates "path" on success. 23098033426eSJeff Layton */ 23108033426eSJeff Layton int 2311197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 23128033426eSJeff Layton struct path *path) 23138033426eSJeff Layton { 23148033426eSJeff Layton struct filename *s = getname(name); 23158033426eSJeff Layton int error; 23168033426eSJeff Layton if (IS_ERR(s)) 23178033426eSJeff Layton return PTR_ERR(s); 23182d864651SAl Viro error = filename_mountpoint(dfd, s, path, flags); 23198033426eSJeff Layton putname(s); 23208033426eSJeff Layton return error; 23218033426eSJeff Layton } 23228033426eSJeff Layton 23232d864651SAl Viro int 23242d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 23252d864651SAl Viro unsigned int flags) 23262d864651SAl Viro { 23272d864651SAl Viro struct filename s = {.name = name}; 23282d864651SAl Viro return filename_mountpoint(dfd, &s, path, flags); 23292d864651SAl Viro } 23302d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 23312d864651SAl Viro 23321da177e4SLinus Torvalds /* 23331da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 23341da177e4SLinus Torvalds * minimal. 23351da177e4SLinus Torvalds */ 23361da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 23371da177e4SLinus Torvalds { 23388e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2339da9592edSDavid Howells 23401da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 23411da177e4SLinus Torvalds return 0; 23428e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 23431da177e4SLinus Torvalds return 0; 23448e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 23451da177e4SLinus Torvalds return 0; 23461a48e2acSEric W. Biederman return !inode_capable(inode, CAP_FOWNER); 23471da177e4SLinus Torvalds } 23481da177e4SLinus Torvalds 23491da177e4SLinus Torvalds /* 23501da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 23511da177e4SLinus Torvalds * whether the type of victim is right. 23521da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 23531da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 23541da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 23551da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 23561da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 23571da177e4SLinus Torvalds * a. be owner of dir, or 23581da177e4SLinus Torvalds * b. be owner of victim, or 23591da177e4SLinus Torvalds * c. have CAP_FOWNER capability 23601da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 23611da177e4SLinus Torvalds * links pointing to it. 23621da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 23631da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 23641da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 23651da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 23661da177e4SLinus Torvalds * nfs_async_unlink(). 23671da177e4SLinus Torvalds */ 2368b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 23691da177e4SLinus Torvalds { 2370b18825a7SDavid Howells struct inode *inode = victim->d_inode; 23711da177e4SLinus Torvalds int error; 23721da177e4SLinus Torvalds 2373b18825a7SDavid Howells if (d_is_negative(victim)) 23741da177e4SLinus Torvalds return -ENOENT; 2375b18825a7SDavid Howells BUG_ON(!inode); 23761da177e4SLinus Torvalds 23771da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 23784fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 23791da177e4SLinus Torvalds 2380f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 23811da177e4SLinus Torvalds if (error) 23821da177e4SLinus Torvalds return error; 23831da177e4SLinus Torvalds if (IS_APPEND(dir)) 23841da177e4SLinus Torvalds return -EPERM; 2385b18825a7SDavid Howells 2386b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2387b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 23881da177e4SLinus Torvalds return -EPERM; 23891da177e4SLinus Torvalds if (isdir) { 2390b18825a7SDavid Howells if (!d_is_directory(victim) && !d_is_autodir(victim)) 23911da177e4SLinus Torvalds return -ENOTDIR; 23921da177e4SLinus Torvalds if (IS_ROOT(victim)) 23931da177e4SLinus Torvalds return -EBUSY; 2394b18825a7SDavid Howells } else if (d_is_directory(victim) || d_is_autodir(victim)) 23951da177e4SLinus Torvalds return -EISDIR; 23961da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 23971da177e4SLinus Torvalds return -ENOENT; 23981da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 23991da177e4SLinus Torvalds return -EBUSY; 24001da177e4SLinus Torvalds return 0; 24011da177e4SLinus Torvalds } 24021da177e4SLinus Torvalds 24031da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 24041da177e4SLinus Torvalds * dir. 24051da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 24061da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 24071da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 24081da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 24091da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 24101da177e4SLinus Torvalds */ 2411a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 24121da177e4SLinus Torvalds { 241314e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 24141da177e4SLinus Torvalds if (child->d_inode) 24151da177e4SLinus Torvalds return -EEXIST; 24161da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 24171da177e4SLinus Torvalds return -ENOENT; 2418f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 24191da177e4SLinus Torvalds } 24201da177e4SLinus Torvalds 24211da177e4SLinus Torvalds /* 24221da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 24231da177e4SLinus Torvalds */ 24241da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 24251da177e4SLinus Torvalds { 24261da177e4SLinus Torvalds struct dentry *p; 24271da177e4SLinus Torvalds 24281da177e4SLinus Torvalds if (p1 == p2) { 2429f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 24301da177e4SLinus Torvalds return NULL; 24311da177e4SLinus Torvalds } 24321da177e4SLinus Torvalds 2433a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 24341da177e4SLinus Torvalds 2435e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2436e2761a11SOGAWA Hirofumi if (p) { 2437f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2438f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 24391da177e4SLinus Torvalds return p; 24401da177e4SLinus Torvalds } 24411da177e4SLinus Torvalds 2442e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2443e2761a11SOGAWA Hirofumi if (p) { 2444f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2445f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 24461da177e4SLinus Torvalds return p; 24471da177e4SLinus Torvalds } 24481da177e4SLinus Torvalds 2449f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2450f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 24511da177e4SLinus Torvalds return NULL; 24521da177e4SLinus Torvalds } 24531da177e4SLinus Torvalds 24541da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 24551da177e4SLinus Torvalds { 24561b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 24571da177e4SLinus Torvalds if (p1 != p2) { 24581b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2459a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 24601da177e4SLinus Torvalds } 24611da177e4SLinus Torvalds } 24621da177e4SLinus Torvalds 24634acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2464312b63fbSAl Viro bool want_excl) 24651da177e4SLinus Torvalds { 2466a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 24671da177e4SLinus Torvalds if (error) 24681da177e4SLinus Torvalds return error; 24691da177e4SLinus Torvalds 2470acfa4380SAl Viro if (!dir->i_op->create) 24711da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 24721da177e4SLinus Torvalds mode &= S_IALLUGO; 24731da177e4SLinus Torvalds mode |= S_IFREG; 24741da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 24751da177e4SLinus Torvalds if (error) 24761da177e4SLinus Torvalds return error; 2477312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2478a74574aaSStephen Smalley if (!error) 2479f38aa942SAmy Griffis fsnotify_create(dir, dentry); 24801da177e4SLinus Torvalds return error; 24811da177e4SLinus Torvalds } 24821da177e4SLinus Torvalds 248373d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 24841da177e4SLinus Torvalds { 24853fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 24861da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 24871da177e4SLinus Torvalds int error; 24881da177e4SLinus Torvalds 2489bcda7652SAl Viro /* O_PATH? */ 2490bcda7652SAl Viro if (!acc_mode) 2491bcda7652SAl Viro return 0; 2492bcda7652SAl Viro 24931da177e4SLinus Torvalds if (!inode) 24941da177e4SLinus Torvalds return -ENOENT; 24951da177e4SLinus Torvalds 2496c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2497c8fe8f30SChristoph Hellwig case S_IFLNK: 24981da177e4SLinus Torvalds return -ELOOP; 2499c8fe8f30SChristoph Hellwig case S_IFDIR: 2500c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 25011da177e4SLinus Torvalds return -EISDIR; 2502c8fe8f30SChristoph Hellwig break; 2503c8fe8f30SChristoph Hellwig case S_IFBLK: 2504c8fe8f30SChristoph Hellwig case S_IFCHR: 25053fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 25061da177e4SLinus Torvalds return -EACCES; 2507c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2508c8fe8f30SChristoph Hellwig case S_IFIFO: 2509c8fe8f30SChristoph Hellwig case S_IFSOCK: 25101da177e4SLinus Torvalds flag &= ~O_TRUNC; 2511c8fe8f30SChristoph Hellwig break; 25124a3fd211SDave Hansen } 2513b41572e9SDave Hansen 25143fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2515b41572e9SDave Hansen if (error) 2516b41572e9SDave Hansen return error; 25176146f0d5SMimi Zohar 25181da177e4SLinus Torvalds /* 25191da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 25201da177e4SLinus Torvalds */ 25211da177e4SLinus Torvalds if (IS_APPEND(inode)) { 25228737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 25237715b521SAl Viro return -EPERM; 25241da177e4SLinus Torvalds if (flag & O_TRUNC) 25257715b521SAl Viro return -EPERM; 25261da177e4SLinus Torvalds } 25271da177e4SLinus Torvalds 25281da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 25292e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 25307715b521SAl Viro return -EPERM; 25311da177e4SLinus Torvalds 2532f3c7691eSJ. Bruce Fields return 0; 25337715b521SAl Viro } 25347715b521SAl Viro 2535e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 25367715b521SAl Viro { 2537e1181ee6SJeff Layton struct path *path = &filp->f_path; 25387715b521SAl Viro struct inode *inode = path->dentry->d_inode; 25397715b521SAl Viro int error = get_write_access(inode); 25401da177e4SLinus Torvalds if (error) 25417715b521SAl Viro return error; 25421da177e4SLinus Torvalds /* 25431da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 25441da177e4SLinus Torvalds */ 25451da177e4SLinus Torvalds error = locks_verify_locked(inode); 2546be6d3e56SKentaro Takeda if (!error) 2547ea0d3ab2STetsuo Handa error = security_path_truncate(path); 25481da177e4SLinus Torvalds if (!error) { 25497715b521SAl Viro error = do_truncate(path->dentry, 0, 2550d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2551e1181ee6SJeff Layton filp); 25521da177e4SLinus Torvalds } 25531da177e4SLinus Torvalds put_write_access(inode); 2554acd0c935SMimi Zohar return error; 25551da177e4SLinus Torvalds } 25561da177e4SLinus Torvalds 2557d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2558d57999e1SDave Hansen { 25598a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 25608a5e929dSAl Viro flag--; 2561d57999e1SDave Hansen return flag; 2562d57999e1SDave Hansen } 2563d57999e1SDave Hansen 2564d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2565d18e9008SMiklos Szeredi { 2566d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2567d18e9008SMiklos Szeredi if (error) 2568d18e9008SMiklos Szeredi return error; 2569d18e9008SMiklos Szeredi 2570d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2571d18e9008SMiklos Szeredi if (error) 2572d18e9008SMiklos Szeredi return error; 2573d18e9008SMiklos Szeredi 2574d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2575d18e9008SMiklos Szeredi } 2576d18e9008SMiklos Szeredi 25771acf0af9SDavid Howells /* 25781acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 25791acf0af9SDavid Howells * dentry. 25801acf0af9SDavid Howells * 25811acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 25821acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 25831acf0af9SDavid Howells * 25841acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 25851acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 25861acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 25871acf0af9SDavid Howells * 25881acf0af9SDavid Howells * Returns an error code otherwise. 25891acf0af9SDavid Howells */ 25902675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 259130d90494SAl Viro struct path *path, struct file *file, 2592015c3bbcSMiklos Szeredi const struct open_flags *op, 259364894cf8SAl Viro bool got_write, bool need_lookup, 259447237687SAl Viro int *opened) 2595d18e9008SMiklos Szeredi { 2596d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2597d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2598d18e9008SMiklos Szeredi umode_t mode; 2599d18e9008SMiklos Szeredi int error; 2600d18e9008SMiklos Szeredi int acc_mode; 2601d18e9008SMiklos Szeredi int create_error = 0; 2602d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2603116cc022SMiklos Szeredi bool excl; 2604d18e9008SMiklos Szeredi 2605d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2606d18e9008SMiklos Szeredi 2607d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2608d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 26092675a4ebSAl Viro error = -ENOENT; 2610d18e9008SMiklos Szeredi goto out; 2611d18e9008SMiklos Szeredi } 2612d18e9008SMiklos Szeredi 261362b259d8SMiklos Szeredi mode = op->mode; 2614d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2615d18e9008SMiklos Szeredi mode &= ~current_umask(); 2616d18e9008SMiklos Szeredi 2617116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2618116cc022SMiklos Szeredi if (excl) 2619d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2620d18e9008SMiklos Szeredi 2621d18e9008SMiklos Szeredi /* 2622d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2623d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2624d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2625d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2626d18e9008SMiklos Szeredi * 2627d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2628d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2629d18e9008SMiklos Szeredi */ 263064894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 263164894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 263264894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2633d18e9008SMiklos Szeredi /* 2634d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2635d18e9008SMiklos Szeredi * back to lookup + open 2636d18e9008SMiklos Szeredi */ 2637d18e9008SMiklos Szeredi goto no_open; 2638d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2639d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 264064894cf8SAl Viro create_error = -EROFS; 2641d18e9008SMiklos Szeredi goto no_open; 2642d18e9008SMiklos Szeredi } else { 2643d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 264464894cf8SAl Viro create_error = -EROFS; 2645d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2646d18e9008SMiklos Szeredi } 2647d18e9008SMiklos Szeredi } 2648d18e9008SMiklos Szeredi 2649d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 265038227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2651d18e9008SMiklos Szeredi if (error) { 2652d18e9008SMiklos Szeredi create_error = error; 2653d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2654d18e9008SMiklos Szeredi goto no_open; 2655d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2656d18e9008SMiklos Szeredi } 2657d18e9008SMiklos Szeredi } 2658d18e9008SMiklos Szeredi 2659d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2660d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2661d18e9008SMiklos Szeredi 266230d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 266330d90494SAl Viro file->f_path.mnt = nd->path.mnt; 266430d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 266547237687SAl Viro opened); 2666d9585277SAl Viro if (error < 0) { 2667d9585277SAl Viro if (create_error && error == -ENOENT) 2668d9585277SAl Viro error = create_error; 2669d18e9008SMiklos Szeredi goto out; 2670d18e9008SMiklos Szeredi } 2671d18e9008SMiklos Szeredi 2672d9585277SAl Viro if (error) { /* returned 1, that is */ 267330d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 26742675a4ebSAl Viro error = -EIO; 2675d18e9008SMiklos Szeredi goto out; 2676d18e9008SMiklos Szeredi } 267730d90494SAl Viro if (file->f_path.dentry) { 2678d18e9008SMiklos Szeredi dput(dentry); 267930d90494SAl Viro dentry = file->f_path.dentry; 2680d18e9008SMiklos Szeredi } 268103da633aSAl Viro if (*opened & FILE_CREATED) 268203da633aSAl Viro fsnotify_create(dir, dentry); 268303da633aSAl Viro if (!dentry->d_inode) { 268403da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 268503da633aSAl Viro if (create_error) { 268662b2ce96SSage Weil error = create_error; 268762b2ce96SSage Weil goto out; 268862b2ce96SSage Weil } 268903da633aSAl Viro } else { 269003da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 269103da633aSAl Viro error = -EEXIST; 269203da633aSAl Viro goto out; 269303da633aSAl Viro } 269403da633aSAl Viro } 2695d18e9008SMiklos Szeredi goto looked_up; 2696d18e9008SMiklos Szeredi } 2697d18e9008SMiklos Szeredi 2698d18e9008SMiklos Szeredi /* 2699d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2700d18e9008SMiklos Szeredi * here. 2701d18e9008SMiklos Szeredi */ 270203da633aSAl Viro acc_mode = op->acc_mode; 270303da633aSAl Viro if (*opened & FILE_CREATED) { 270403da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 270503da633aSAl Viro fsnotify_create(dir, dentry); 270603da633aSAl Viro acc_mode = MAY_OPEN; 270703da633aSAl Viro } 27082675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 27092675a4ebSAl Viro if (error) 27102675a4ebSAl Viro fput(file); 2711d18e9008SMiklos Szeredi 2712d18e9008SMiklos Szeredi out: 2713d18e9008SMiklos Szeredi dput(dentry); 27142675a4ebSAl Viro return error; 2715d18e9008SMiklos Szeredi 2716d18e9008SMiklos Szeredi no_open: 2717d18e9008SMiklos Szeredi if (need_lookup) { 271872bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2719d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 27202675a4ebSAl Viro return PTR_ERR(dentry); 2721d18e9008SMiklos Szeredi 2722d18e9008SMiklos Szeredi if (create_error) { 2723d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2724d18e9008SMiklos Szeredi 27252675a4ebSAl Viro error = create_error; 2726d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2727d18e9008SMiklos Szeredi if (!dentry->d_inode) 2728d18e9008SMiklos Szeredi goto out; 2729d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2730d18e9008SMiklos Szeredi goto out; 2731d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2732d18e9008SMiklos Szeredi S_ISREG(dentry->d_inode->i_mode)) { 2733d18e9008SMiklos Szeredi goto out; 2734d18e9008SMiklos Szeredi } 2735d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2736d18e9008SMiklos Szeredi } 2737d18e9008SMiklos Szeredi } 2738d18e9008SMiklos Szeredi looked_up: 2739d18e9008SMiklos Szeredi path->dentry = dentry; 2740d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 27412675a4ebSAl Viro return 1; 2742d18e9008SMiklos Szeredi } 2743d18e9008SMiklos Szeredi 274431e6b01fSNick Piggin /* 27451acf0af9SDavid Howells * Look up and maybe create and open the last component. 2746d58ffd35SMiklos Szeredi * 2747d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2748d58ffd35SMiklos Szeredi * 27491acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 27501acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 27511acf0af9SDavid Howells * 27521acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 27531acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 27541acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 27551acf0af9SDavid Howells * specified then a negative dentry may be returned. 27561acf0af9SDavid Howells * 27571acf0af9SDavid Howells * An error code is returned otherwise. 27581acf0af9SDavid Howells * 27591acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 27601acf0af9SDavid Howells * cleared otherwise prior to returning. 2761d58ffd35SMiklos Szeredi */ 27622675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 276330d90494SAl Viro struct file *file, 2764d58ffd35SMiklos Szeredi const struct open_flags *op, 276564894cf8SAl Viro bool got_write, int *opened) 2766d58ffd35SMiklos Szeredi { 2767d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 276854ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2769d58ffd35SMiklos Szeredi struct dentry *dentry; 2770d58ffd35SMiklos Szeredi int error; 277154ef4872SMiklos Szeredi bool need_lookup; 2772d58ffd35SMiklos Szeredi 277347237687SAl Viro *opened &= ~FILE_CREATED; 2774201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2775d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 27762675a4ebSAl Viro return PTR_ERR(dentry); 2777d58ffd35SMiklos Szeredi 2778d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2779d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2780d18e9008SMiklos Szeredi goto out_no_open; 2781d18e9008SMiklos Szeredi 2782d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 278364894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 278447237687SAl Viro need_lookup, opened); 2785d18e9008SMiklos Szeredi } 2786d18e9008SMiklos Szeredi 278754ef4872SMiklos Szeredi if (need_lookup) { 278854ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 278954ef4872SMiklos Szeredi 279072bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 279154ef4872SMiklos Szeredi if (IS_ERR(dentry)) 27922675a4ebSAl Viro return PTR_ERR(dentry); 279354ef4872SMiklos Szeredi } 279454ef4872SMiklos Szeredi 2795d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2796d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2797d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2798d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2799d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2800d58ffd35SMiklos Szeredi /* 2801d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2802d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2803d58ffd35SMiklos Szeredi * the time when the file is created and when 2804d58ffd35SMiklos Szeredi * a permanent write count is taken through 2805015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 2806d58ffd35SMiklos Szeredi */ 280764894cf8SAl Viro if (!got_write) { 280864894cf8SAl Viro error = -EROFS; 2809d58ffd35SMiklos Szeredi goto out_dput; 281064894cf8SAl Viro } 281147237687SAl Viro *opened |= FILE_CREATED; 2812d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2813d58ffd35SMiklos Szeredi if (error) 2814d58ffd35SMiklos Szeredi goto out_dput; 2815312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 2816312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 2817d58ffd35SMiklos Szeredi if (error) 2818d58ffd35SMiklos Szeredi goto out_dput; 2819d58ffd35SMiklos Szeredi } 2820d18e9008SMiklos Szeredi out_no_open: 2821d58ffd35SMiklos Szeredi path->dentry = dentry; 2822d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 28232675a4ebSAl Viro return 1; 2824d58ffd35SMiklos Szeredi 2825d58ffd35SMiklos Szeredi out_dput: 2826d58ffd35SMiklos Szeredi dput(dentry); 28272675a4ebSAl Viro return error; 2828d58ffd35SMiklos Szeredi } 2829d58ffd35SMiklos Szeredi 2830d58ffd35SMiklos Szeredi /* 2831fe2d35ffSAl Viro * Handle the last step of open() 283231e6b01fSNick Piggin */ 28332675a4ebSAl Viro static int do_last(struct nameidata *nd, struct path *path, 283430d90494SAl Viro struct file *file, const struct open_flags *op, 2835669abf4eSJeff Layton int *opened, struct filename *name) 2836fb1cc555SAl Viro { 2837a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2838ca344a89SAl Viro int open_flag = op->open_flag; 283977d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 284064894cf8SAl Viro bool got_write = false; 2841bcda7652SAl Viro int acc_mode = op->acc_mode; 2842a1eb3315SMiklos Szeredi struct inode *inode; 284377d660a8SMiklos Szeredi bool symlink_ok = false; 284416b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 284516b1c1cdSMiklos Szeredi bool retried = false; 284616c2cd71SAl Viro int error; 2847fb1cc555SAl Viro 2848c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2849c3e380b0SAl Viro nd->flags |= op->intent; 2850c3e380b0SAl Viro 2851bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 2852fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2853fe2d35ffSAl Viro if (error) 28542675a4ebSAl Viro return error; 2855e83db167SMiklos Szeredi goto finish_open; 28561f36f774SAl Viro } 2857a2c36b45SAl Viro 2858ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2859fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2860fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2861bcda7652SAl Viro if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) 286277d660a8SMiklos Szeredi symlink_ok = true; 2863fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2864e97cdc87SAl Viro error = lookup_fast(nd, path, &inode); 286571574865SMiklos Szeredi if (likely(!error)) 286671574865SMiklos Szeredi goto finish_lookup; 286771574865SMiklos Szeredi 2868ce57dfc1SAl Viro if (error < 0) 28692675a4ebSAl Viro goto out; 2870a1eb3315SMiklos Szeredi 287137d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 2872b6183df7SMiklos Szeredi } else { 2873fe2d35ffSAl Viro /* create side of things */ 2874a3fbbde7SAl Viro /* 2875b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 2876b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 2877b6183df7SMiklos Szeredi * about to look up 2878a3fbbde7SAl Viro */ 28799f1fafeeSAl Viro error = complete_walk(nd); 28809f1fafeeSAl Viro if (error) 28812675a4ebSAl Viro return error; 2882fe2d35ffSAl Viro 288333e2208aSJeff Layton audit_inode(name, dir, LOOKUP_PARENT); 288416c2cd71SAl Viro error = -EISDIR; 28851f36f774SAl Viro /* trailing slashes? */ 288631e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 28872675a4ebSAl Viro goto out; 2888b6183df7SMiklos Szeredi } 28891f36f774SAl Viro 289016b1c1cdSMiklos Szeredi retry_lookup: 289164894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 289264894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 289364894cf8SAl Viro if (!error) 289464894cf8SAl Viro got_write = true; 289564894cf8SAl Viro /* 289664894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 289764894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 289864894cf8SAl Viro * dropping this one anyway. 289964894cf8SAl Viro */ 290064894cf8SAl Viro } 2901a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 290264894cf8SAl Viro error = lookup_open(nd, path, file, op, got_write, opened); 2903fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2904fb1cc555SAl Viro 29052675a4ebSAl Viro if (error <= 0) { 29062675a4ebSAl Viro if (error) 2907d58ffd35SMiklos Szeredi goto out; 29086c0d46c4SAl Viro 290947237687SAl Viro if ((*opened & FILE_CREATED) || 2910496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 291177d660a8SMiklos Szeredi will_truncate = false; 2912d18e9008SMiklos Szeredi 2913adb5c247SJeff Layton audit_inode(name, file->f_path.dentry, 0); 2914d18e9008SMiklos Szeredi goto opened; 2915d18e9008SMiklos Szeredi } 2916d18e9008SMiklos Szeredi 291747237687SAl Viro if (*opened & FILE_CREATED) { 29189b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 2919ca344a89SAl Viro open_flag &= ~O_TRUNC; 292077d660a8SMiklos Szeredi will_truncate = false; 2921bcda7652SAl Viro acc_mode = MAY_OPEN; 2922d58ffd35SMiklos Szeredi path_to_nameidata(path, nd); 2923e83db167SMiklos Szeredi goto finish_open_created; 2924fb1cc555SAl Viro } 2925fb1cc555SAl Viro 2926fb1cc555SAl Viro /* 29273134f37eSJeff Layton * create/update audit record if it already exists. 2928fb1cc555SAl Viro */ 2929b18825a7SDavid Howells if (d_is_positive(path->dentry)) 2930adb5c247SJeff Layton audit_inode(name, path->dentry, 0); 2931fb1cc555SAl Viro 2932d18e9008SMiklos Szeredi /* 2933d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 2934d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 2935d18e9008SMiklos Szeredi * necessary...) 2936d18e9008SMiklos Szeredi */ 293764894cf8SAl Viro if (got_write) { 2938d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 293964894cf8SAl Viro got_write = false; 2940d18e9008SMiklos Szeredi } 2941d18e9008SMiklos Szeredi 2942fb1cc555SAl Viro error = -EEXIST; 2943f8310c59SAl Viro if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) 2944fb1cc555SAl Viro goto exit_dput; 2945fb1cc555SAl Viro 29469875cf80SDavid Howells error = follow_managed(path, nd->flags); 29479875cf80SDavid Howells if (error < 0) 2948fb1cc555SAl Viro goto exit_dput; 2949fb1cc555SAl Viro 2950a3fbbde7SAl Viro if (error) 2951a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 2952a3fbbde7SAl Viro 2953decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 2954decf3400SMiklos Szeredi inode = path->dentry->d_inode; 29555f5daac1SMiklos Szeredi finish_lookup: 29565f5daac1SMiklos Szeredi /* we _can_ be in RCU mode here */ 2957fb1cc555SAl Viro error = -ENOENT; 2958b18825a7SDavid Howells if (d_is_negative(path->dentry)) { 295954c33e7fSMiklos Szeredi path_to_nameidata(path, nd); 29602675a4ebSAl Viro goto out; 296154c33e7fSMiklos Szeredi } 29629e67f361SAl Viro 2963b18825a7SDavid Howells if (should_follow_link(path->dentry, !symlink_ok)) { 2964d45ea867SMiklos Szeredi if (nd->flags & LOOKUP_RCU) { 2965d45ea867SMiklos Szeredi if (unlikely(unlazy_walk(nd, path->dentry))) { 2966d45ea867SMiklos Szeredi error = -ECHILD; 29672675a4ebSAl Viro goto out; 2968d45ea867SMiklos Szeredi } 2969d45ea867SMiklos Szeredi } 2970d45ea867SMiklos Szeredi BUG_ON(inode != path->dentry->d_inode); 29712675a4ebSAl Viro return 1; 2972d45ea867SMiklos Szeredi } 2973fb1cc555SAl Viro 297416b1c1cdSMiklos Szeredi if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path->mnt) { 2975fb1cc555SAl Viro path_to_nameidata(path, nd); 297616b1c1cdSMiklos Szeredi } else { 297716b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 297816b1c1cdSMiklos Szeredi save_parent.mnt = mntget(path->mnt); 297916b1c1cdSMiklos Szeredi nd->path.dentry = path->dentry; 298016b1c1cdSMiklos Szeredi 298116b1c1cdSMiklos Szeredi } 2982decf3400SMiklos Szeredi nd->inode = inode; 2983a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 2984bc77daa7SAl Viro finish_open: 2985a3fbbde7SAl Viro error = complete_walk(nd); 298616b1c1cdSMiklos Szeredi if (error) { 298716b1c1cdSMiklos Szeredi path_put(&save_parent); 29882675a4ebSAl Viro return error; 298916b1c1cdSMiklos Szeredi } 2990bc77daa7SAl Viro audit_inode(name, nd->path.dentry, 0); 2991fb1cc555SAl Viro error = -EISDIR; 2992b18825a7SDavid Howells if ((open_flag & O_CREAT) && 2993b18825a7SDavid Howells (d_is_directory(nd->path.dentry) || d_is_autodir(nd->path.dentry))) 29942675a4ebSAl Viro goto out; 2995af2f5542SMiklos Szeredi error = -ENOTDIR; 2996b18825a7SDavid Howells if ((nd->flags & LOOKUP_DIRECTORY) && !d_is_directory(nd->path.dentry)) 29972675a4ebSAl Viro goto out; 29986c0d46c4SAl Viro if (!S_ISREG(nd->inode->i_mode)) 299977d660a8SMiklos Szeredi will_truncate = false; 30006c0d46c4SAl Viro 30010f9d1a10SAl Viro if (will_truncate) { 30020f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 30030f9d1a10SAl Viro if (error) 30042675a4ebSAl Viro goto out; 300564894cf8SAl Viro got_write = true; 30060f9d1a10SAl Viro } 3007e83db167SMiklos Szeredi finish_open_created: 3008bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3009ca344a89SAl Viro if (error) 30102675a4ebSAl Viro goto out; 301130d90494SAl Viro file->f_path.mnt = nd->path.mnt; 301230d90494SAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 301330d90494SAl Viro if (error) { 301430d90494SAl Viro if (error == -EOPENSTALE) 3015f60dc3dbSMiklos Szeredi goto stale_open; 3016015c3bbcSMiklos Szeredi goto out; 3017f60dc3dbSMiklos Szeredi } 3018a8277b9bSMiklos Szeredi opened: 30192675a4ebSAl Viro error = open_check_o_direct(file); 3020015c3bbcSMiklos Szeredi if (error) 3021015c3bbcSMiklos Szeredi goto exit_fput; 30222675a4ebSAl Viro error = ima_file_check(file, op->acc_mode); 3023aa4caadbSMiklos Szeredi if (error) 3024aa4caadbSMiklos Szeredi goto exit_fput; 3025aa4caadbSMiklos Szeredi 30260f9d1a10SAl Viro if (will_truncate) { 30272675a4ebSAl Viro error = handle_truncate(file); 3028aa4caadbSMiklos Szeredi if (error) 3029aa4caadbSMiklos Szeredi goto exit_fput; 30300f9d1a10SAl Viro } 3031ca344a89SAl Viro out: 303264894cf8SAl Viro if (got_write) 30330f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 303416b1c1cdSMiklos Szeredi path_put(&save_parent); 3035e276ae67SMiklos Szeredi terminate_walk(nd); 30362675a4ebSAl Viro return error; 3037fb1cc555SAl Viro 3038fb1cc555SAl Viro exit_dput: 3039fb1cc555SAl Viro path_put_conditional(path, nd); 3040ca344a89SAl Viro goto out; 3041015c3bbcSMiklos Szeredi exit_fput: 30422675a4ebSAl Viro fput(file); 30432675a4ebSAl Viro goto out; 3044015c3bbcSMiklos Szeredi 3045f60dc3dbSMiklos Szeredi stale_open: 3046f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3047f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3048f60dc3dbSMiklos Szeredi goto out; 3049f60dc3dbSMiklos Szeredi 3050f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3051f60dc3dbSMiklos Szeredi path_put(&nd->path); 3052f60dc3dbSMiklos Szeredi nd->path = save_parent; 3053f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3054f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3055f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 305664894cf8SAl Viro if (got_write) { 3057f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 305864894cf8SAl Viro got_write = false; 3059f60dc3dbSMiklos Szeredi } 3060f60dc3dbSMiklos Szeredi retried = true; 3061f60dc3dbSMiklos Szeredi goto retry_lookup; 3062fb1cc555SAl Viro } 3063fb1cc555SAl Viro 306460545d0dSAl Viro static int do_tmpfile(int dfd, struct filename *pathname, 306560545d0dSAl Viro struct nameidata *nd, int flags, 306660545d0dSAl Viro const struct open_flags *op, 306760545d0dSAl Viro struct file *file, int *opened) 306860545d0dSAl Viro { 306960545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 307060545d0dSAl Viro struct dentry *dentry, *child; 307160545d0dSAl Viro struct inode *dir; 307260545d0dSAl Viro int error = path_lookupat(dfd, pathname->name, 307360545d0dSAl Viro flags | LOOKUP_DIRECTORY, nd); 307460545d0dSAl Viro if (unlikely(error)) 307560545d0dSAl Viro return error; 307660545d0dSAl Viro error = mnt_want_write(nd->path.mnt); 307760545d0dSAl Viro if (unlikely(error)) 307860545d0dSAl Viro goto out; 307960545d0dSAl Viro /* we want directory to be writable */ 308060545d0dSAl Viro error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); 308160545d0dSAl Viro if (error) 308260545d0dSAl Viro goto out2; 308360545d0dSAl Viro dentry = nd->path.dentry; 308460545d0dSAl Viro dir = dentry->d_inode; 308560545d0dSAl Viro if (!dir->i_op->tmpfile) { 308660545d0dSAl Viro error = -EOPNOTSUPP; 308760545d0dSAl Viro goto out2; 308860545d0dSAl Viro } 308960545d0dSAl Viro child = d_alloc(dentry, &name); 309060545d0dSAl Viro if (unlikely(!child)) { 309160545d0dSAl Viro error = -ENOMEM; 309260545d0dSAl Viro goto out2; 309360545d0dSAl Viro } 309460545d0dSAl Viro nd->flags &= ~LOOKUP_DIRECTORY; 309560545d0dSAl Viro nd->flags |= op->intent; 309660545d0dSAl Viro dput(nd->path.dentry); 309760545d0dSAl Viro nd->path.dentry = child; 309860545d0dSAl Viro error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); 309960545d0dSAl Viro if (error) 310060545d0dSAl Viro goto out2; 310160545d0dSAl Viro audit_inode(pathname, nd->path.dentry, 0); 310260545d0dSAl Viro error = may_open(&nd->path, op->acc_mode, op->open_flag); 310360545d0dSAl Viro if (error) 310460545d0dSAl Viro goto out2; 310560545d0dSAl Viro file->f_path.mnt = nd->path.mnt; 310660545d0dSAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 310760545d0dSAl Viro if (error) 310860545d0dSAl Viro goto out2; 310960545d0dSAl Viro error = open_check_o_direct(file); 3110f4e0c30cSAl Viro if (error) { 311160545d0dSAl Viro fput(file); 3112f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3113f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3114f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3115f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3116f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3117f4e0c30cSAl Viro } 311860545d0dSAl Viro out2: 311960545d0dSAl Viro mnt_drop_write(nd->path.mnt); 312060545d0dSAl Viro out: 312160545d0dSAl Viro path_put(&nd->path); 312260545d0dSAl Viro return error; 312360545d0dSAl Viro } 312460545d0dSAl Viro 3125669abf4eSJeff Layton static struct file *path_openat(int dfd, struct filename *pathname, 312673d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 31271da177e4SLinus Torvalds { 3128fe2d35ffSAl Viro struct file *base = NULL; 312930d90494SAl Viro struct file *file; 31309850c056SAl Viro struct path path; 313147237687SAl Viro int opened = 0; 313213aab428SAl Viro int error; 313331e6b01fSNick Piggin 313430d90494SAl Viro file = get_empty_filp(); 31351afc99beSAl Viro if (IS_ERR(file)) 31361afc99beSAl Viro return file; 313731e6b01fSNick Piggin 313830d90494SAl Viro file->f_flags = op->open_flag; 313931e6b01fSNick Piggin 3140bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 314160545d0dSAl Viro error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); 314260545d0dSAl Viro goto out; 314360545d0dSAl Viro } 314460545d0dSAl Viro 3145669abf4eSJeff Layton error = path_init(dfd, pathname->name, flags | LOOKUP_PARENT, nd, &base); 314631e6b01fSNick Piggin if (unlikely(error)) 31472675a4ebSAl Viro goto out; 314831e6b01fSNick Piggin 3149fe2d35ffSAl Viro current->total_link_count = 0; 3150669abf4eSJeff Layton error = link_path_walk(pathname->name, nd); 315131e6b01fSNick Piggin if (unlikely(error)) 31522675a4ebSAl Viro goto out; 31531da177e4SLinus Torvalds 31542675a4ebSAl Viro error = do_last(nd, &path, file, op, &opened, pathname); 31552675a4ebSAl Viro while (unlikely(error > 0)) { /* trailing symlink */ 31567b9337aaSNick Piggin struct path link = path; 3157def4af30SAl Viro void *cookie; 3158574197e0SAl Viro if (!(nd->flags & LOOKUP_FOLLOW)) { 315973d049a4SAl Viro path_put_conditional(&path, nd); 316073d049a4SAl Viro path_put(&nd->path); 31612675a4ebSAl Viro error = -ELOOP; 316240b39136SAl Viro break; 316340b39136SAl Viro } 3164800179c9SKees Cook error = may_follow_link(&link, nd); 3165800179c9SKees Cook if (unlikely(error)) 3166800179c9SKees Cook break; 316773d049a4SAl Viro nd->flags |= LOOKUP_PARENT; 316873d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 3169574197e0SAl Viro error = follow_link(&link, nd, &cookie); 3170c3e380b0SAl Viro if (unlikely(error)) 31712675a4ebSAl Viro break; 31722675a4ebSAl Viro error = do_last(nd, &path, file, op, &opened, pathname); 3173574197e0SAl Viro put_link(nd, &link, cookie); 3174806b681cSAl Viro } 317510fa8e62SAl Viro out: 317673d049a4SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) 317773d049a4SAl Viro path_put(&nd->root); 3178fe2d35ffSAl Viro if (base) 3179fe2d35ffSAl Viro fput(base); 31802675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 31812675a4ebSAl Viro BUG_ON(!error); 318230d90494SAl Viro put_filp(file); 3183015c3bbcSMiklos Szeredi } 31842675a4ebSAl Viro if (unlikely(error)) { 31852675a4ebSAl Viro if (error == -EOPENSTALE) { 31862675a4ebSAl Viro if (flags & LOOKUP_RCU) 31872675a4ebSAl Viro error = -ECHILD; 31882675a4ebSAl Viro else 31892675a4ebSAl Viro error = -ESTALE; 31902675a4ebSAl Viro } 31912675a4ebSAl Viro file = ERR_PTR(error); 31922675a4ebSAl Viro } 31932675a4ebSAl Viro return file; 3194de459215SKirill Korotaev } 31951da177e4SLinus Torvalds 3196669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3197f9652e10SAl Viro const struct open_flags *op) 319813aab428SAl Viro { 319973d049a4SAl Viro struct nameidata nd; 3200f9652e10SAl Viro int flags = op->lookup_flags; 320113aab428SAl Viro struct file *filp; 320213aab428SAl Viro 320373d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 320413aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 320573d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 320613aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 320773d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 320813aab428SAl Viro return filp; 320913aab428SAl Viro } 321013aab428SAl Viro 321173d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3212f9652e10SAl Viro const char *name, const struct open_flags *op) 321373d049a4SAl Viro { 321473d049a4SAl Viro struct nameidata nd; 321573d049a4SAl Viro struct file *file; 3216669abf4eSJeff Layton struct filename filename = { .name = name }; 3217f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 321873d049a4SAl Viro 321973d049a4SAl Viro nd.root.mnt = mnt; 322073d049a4SAl Viro nd.root.dentry = dentry; 322173d049a4SAl Viro 3222b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 322373d049a4SAl Viro return ERR_PTR(-ELOOP); 322473d049a4SAl Viro 3225669abf4eSJeff Layton file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_RCU); 322673d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3227669abf4eSJeff Layton file = path_openat(-1, &filename, &nd, op, flags); 322873d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3229669abf4eSJeff Layton file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_REVAL); 323073d049a4SAl Viro return file; 323173d049a4SAl Viro } 323273d049a4SAl Viro 32331ac12b4bSJeff Layton struct dentry *kern_path_create(int dfd, const char *pathname, 32341ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 32351da177e4SLinus Torvalds { 3236c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3237ed75e95dSAl Viro struct nameidata nd; 3238c30dabfeSJan Kara int err2; 32391ac12b4bSJeff Layton int error; 32401ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 32411ac12b4bSJeff Layton 32421ac12b4bSJeff Layton /* 32431ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 32441ac12b4bSJeff Layton * other flags passed in are ignored! 32451ac12b4bSJeff Layton */ 32461ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 32471ac12b4bSJeff Layton 32481ac12b4bSJeff Layton error = do_path_lookup(dfd, pathname, LOOKUP_PARENT|lookup_flags, &nd); 3249ed75e95dSAl Viro if (error) 3250ed75e95dSAl Viro return ERR_PTR(error); 32511da177e4SLinus Torvalds 3252c663e5d8SChristoph Hellwig /* 3253c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3254c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3255c663e5d8SChristoph Hellwig */ 3256ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 3257ed75e95dSAl Viro goto out; 3258ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 3259ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 3260c663e5d8SChristoph Hellwig 3261c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3262c30dabfeSJan Kara err2 = mnt_want_write(nd.path.mnt); 3263c663e5d8SChristoph Hellwig /* 3264c663e5d8SChristoph Hellwig * Do the final lookup. 3265c663e5d8SChristoph Hellwig */ 3266ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3267ed75e95dSAl Viro dentry = lookup_hash(&nd); 32681da177e4SLinus Torvalds if (IS_ERR(dentry)) 3269a8104a9fSAl Viro goto unlock; 3270c663e5d8SChristoph Hellwig 3271a8104a9fSAl Viro error = -EEXIST; 3272b18825a7SDavid Howells if (d_is_positive(dentry)) 3273a8104a9fSAl Viro goto fail; 3274b18825a7SDavid Howells 3275c663e5d8SChristoph Hellwig /* 3276c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3277c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3278c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3279c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3280c663e5d8SChristoph Hellwig */ 3281ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 3282a8104a9fSAl Viro error = -ENOENT; 3283ed75e95dSAl Viro goto fail; 3284e9baf6e5SAl Viro } 3285c30dabfeSJan Kara if (unlikely(err2)) { 3286c30dabfeSJan Kara error = err2; 3287a8104a9fSAl Viro goto fail; 3288c30dabfeSJan Kara } 3289ed75e95dSAl Viro *path = nd.path; 3290e9baf6e5SAl Viro return dentry; 32911da177e4SLinus Torvalds fail: 3292a8104a9fSAl Viro dput(dentry); 3293a8104a9fSAl Viro dentry = ERR_PTR(error); 3294a8104a9fSAl Viro unlock: 3295dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3296c30dabfeSJan Kara if (!err2) 3297c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 3298ed75e95dSAl Viro out: 3299dae6ad8fSAl Viro path_put(&nd.path); 3300ed75e95dSAl Viro return dentry; 3301dae6ad8fSAl Viro } 3302dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3303dae6ad8fSAl Viro 3304921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3305921a1650SAl Viro { 3306921a1650SAl Viro dput(dentry); 3307921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3308a8104a9fSAl Viro mnt_drop_write(path->mnt); 3309921a1650SAl Viro path_put(path); 3310921a1650SAl Viro } 3311921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3312921a1650SAl Viro 33131ac12b4bSJeff Layton struct dentry *user_path_create(int dfd, const char __user *pathname, 33141ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3315dae6ad8fSAl Viro { 331691a27b2aSJeff Layton struct filename *tmp = getname(pathname); 3317dae6ad8fSAl Viro struct dentry *res; 3318dae6ad8fSAl Viro if (IS_ERR(tmp)) 3319dae6ad8fSAl Viro return ERR_CAST(tmp); 33201ac12b4bSJeff Layton res = kern_path_create(dfd, tmp->name, path, lookup_flags); 3321dae6ad8fSAl Viro putname(tmp); 3322dae6ad8fSAl Viro return res; 3323dae6ad8fSAl Viro } 3324dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3325dae6ad8fSAl Viro 33261a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 33271da177e4SLinus Torvalds { 3328a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 33291da177e4SLinus Torvalds 33301da177e4SLinus Torvalds if (error) 33311da177e4SLinus Torvalds return error; 33321da177e4SLinus Torvalds 3333975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 33341da177e4SLinus Torvalds return -EPERM; 33351da177e4SLinus Torvalds 3336acfa4380SAl Viro if (!dir->i_op->mknod) 33371da177e4SLinus Torvalds return -EPERM; 33381da177e4SLinus Torvalds 333908ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 334008ce5f16SSerge E. Hallyn if (error) 334108ce5f16SSerge E. Hallyn return error; 334208ce5f16SSerge E. Hallyn 33431da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 33441da177e4SLinus Torvalds if (error) 33451da177e4SLinus Torvalds return error; 33461da177e4SLinus Torvalds 33471da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3348a74574aaSStephen Smalley if (!error) 3349f38aa942SAmy Griffis fsnotify_create(dir, dentry); 33501da177e4SLinus Torvalds return error; 33511da177e4SLinus Torvalds } 33521da177e4SLinus Torvalds 3353f69aac00SAl Viro static int may_mknod(umode_t mode) 3354463c3197SDave Hansen { 3355463c3197SDave Hansen switch (mode & S_IFMT) { 3356463c3197SDave Hansen case S_IFREG: 3357463c3197SDave Hansen case S_IFCHR: 3358463c3197SDave Hansen case S_IFBLK: 3359463c3197SDave Hansen case S_IFIFO: 3360463c3197SDave Hansen case S_IFSOCK: 3361463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3362463c3197SDave Hansen return 0; 3363463c3197SDave Hansen case S_IFDIR: 3364463c3197SDave Hansen return -EPERM; 3365463c3197SDave Hansen default: 3366463c3197SDave Hansen return -EINVAL; 3367463c3197SDave Hansen } 3368463c3197SDave Hansen } 3369463c3197SDave Hansen 33708208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 33712e4d0924SHeiko Carstens unsigned, dev) 33721da177e4SLinus Torvalds { 33731da177e4SLinus Torvalds struct dentry *dentry; 3374dae6ad8fSAl Viro struct path path; 3375dae6ad8fSAl Viro int error; 3376972567f1SJeff Layton unsigned int lookup_flags = 0; 33771da177e4SLinus Torvalds 33788e4bfca1SAl Viro error = may_mknod(mode); 33798e4bfca1SAl Viro if (error) 33808e4bfca1SAl Viro return error; 3381972567f1SJeff Layton retry: 3382972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3383dae6ad8fSAl Viro if (IS_ERR(dentry)) 3384dae6ad8fSAl Viro return PTR_ERR(dentry); 33852ad94ae6SAl Viro 3386dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3387ce3b0f8dSAl Viro mode &= ~current_umask(); 3388dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3389be6d3e56SKentaro Takeda if (error) 3390a8104a9fSAl Viro goto out; 33911da177e4SLinus Torvalds switch (mode & S_IFMT) { 33921da177e4SLinus Torvalds case 0: case S_IFREG: 3393312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 33941da177e4SLinus Torvalds break; 33951da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3396dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 33971da177e4SLinus Torvalds new_decode_dev(dev)); 33981da177e4SLinus Torvalds break; 33991da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3400dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 34011da177e4SLinus Torvalds break; 34021da177e4SLinus Torvalds } 3403a8104a9fSAl Viro out: 3404921a1650SAl Viro done_path_create(&path, dentry); 3405972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3406972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3407972567f1SJeff Layton goto retry; 3408972567f1SJeff Layton } 34091da177e4SLinus Torvalds return error; 34101da177e4SLinus Torvalds } 34111da177e4SLinus Torvalds 34128208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 34135590ff0dSUlrich Drepper { 34145590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 34155590ff0dSUlrich Drepper } 34165590ff0dSUlrich Drepper 341718bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 34181da177e4SLinus Torvalds { 3419a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 34208de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 34211da177e4SLinus Torvalds 34221da177e4SLinus Torvalds if (error) 34231da177e4SLinus Torvalds return error; 34241da177e4SLinus Torvalds 3425acfa4380SAl Viro if (!dir->i_op->mkdir) 34261da177e4SLinus Torvalds return -EPERM; 34271da177e4SLinus Torvalds 34281da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 34291da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 34301da177e4SLinus Torvalds if (error) 34311da177e4SLinus Torvalds return error; 34321da177e4SLinus Torvalds 34338de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 34348de52778SAl Viro return -EMLINK; 34358de52778SAl Viro 34361da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3437a74574aaSStephen Smalley if (!error) 3438f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 34391da177e4SLinus Torvalds return error; 34401da177e4SLinus Torvalds } 34411da177e4SLinus Torvalds 3442a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 34431da177e4SLinus Torvalds { 34446902d925SDave Hansen struct dentry *dentry; 3445dae6ad8fSAl Viro struct path path; 3446dae6ad8fSAl Viro int error; 3447b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 34481da177e4SLinus Torvalds 3449b76d8b82SJeff Layton retry: 3450b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 34516902d925SDave Hansen if (IS_ERR(dentry)) 3452dae6ad8fSAl Viro return PTR_ERR(dentry); 34536902d925SDave Hansen 3454dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3455ce3b0f8dSAl Viro mode &= ~current_umask(); 3456dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3457a8104a9fSAl Viro if (!error) 3458dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3459921a1650SAl Viro done_path_create(&path, dentry); 3460b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3461b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3462b76d8b82SJeff Layton goto retry; 3463b76d8b82SJeff Layton } 34641da177e4SLinus Torvalds return error; 34651da177e4SLinus Torvalds } 34661da177e4SLinus Torvalds 3467a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 34685590ff0dSUlrich Drepper { 34695590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 34705590ff0dSUlrich Drepper } 34715590ff0dSUlrich Drepper 34721da177e4SLinus Torvalds /* 3473a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3474c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3475a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3476a71905f0SSage Weil * then we drop the dentry now. 34771da177e4SLinus Torvalds * 34781da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 34791da177e4SLinus Torvalds * do a 34801da177e4SLinus Torvalds * 34811da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 34821da177e4SLinus Torvalds * return -EBUSY; 34831da177e4SLinus Torvalds * 34841da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 34851da177e4SLinus Torvalds * that is still in use by something else.. 34861da177e4SLinus Torvalds */ 34871da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 34881da177e4SLinus Torvalds { 34891da177e4SLinus Torvalds shrink_dcache_parent(dentry); 34901da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 349198474236SWaiman Long if (dentry->d_lockref.count == 1) 34921da177e4SLinus Torvalds __d_drop(dentry); 34931da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 34941da177e4SLinus Torvalds } 34951da177e4SLinus Torvalds 34961da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 34971da177e4SLinus Torvalds { 34981da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 34991da177e4SLinus Torvalds 35001da177e4SLinus Torvalds if (error) 35011da177e4SLinus Torvalds return error; 35021da177e4SLinus Torvalds 3503acfa4380SAl Viro if (!dir->i_op->rmdir) 35041da177e4SLinus Torvalds return -EPERM; 35051da177e4SLinus Torvalds 35061d2ef590SAl Viro dget(dentry); 35071b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3508912dbc15SSage Weil 35091da177e4SLinus Torvalds error = -EBUSY; 3510912dbc15SSage Weil if (d_mountpoint(dentry)) 3511912dbc15SSage Weil goto out; 3512912dbc15SSage Weil 35131da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3514912dbc15SSage Weil if (error) 3515912dbc15SSage Weil goto out; 3516912dbc15SSage Weil 35173cebde24SSage Weil shrink_dcache_parent(dentry); 35181da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3519912dbc15SSage Weil if (error) 3520912dbc15SSage Weil goto out; 3521912dbc15SSage Weil 35221da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3523d83c49f3SAl Viro dont_mount(dentry); 35241da177e4SLinus Torvalds 3525912dbc15SSage Weil out: 3526912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 35271d2ef590SAl Viro dput(dentry); 3528912dbc15SSage Weil if (!error) 3529912dbc15SSage Weil d_delete(dentry); 35301da177e4SLinus Torvalds return error; 35311da177e4SLinus Torvalds } 35321da177e4SLinus Torvalds 35335590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 35341da177e4SLinus Torvalds { 35351da177e4SLinus Torvalds int error = 0; 353691a27b2aSJeff Layton struct filename *name; 35371da177e4SLinus Torvalds struct dentry *dentry; 35381da177e4SLinus Torvalds struct nameidata nd; 3539c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3540c6ee9206SJeff Layton retry: 3541c6ee9206SJeff Layton name = user_path_parent(dfd, pathname, &nd, lookup_flags); 354291a27b2aSJeff Layton if (IS_ERR(name)) 354391a27b2aSJeff Layton return PTR_ERR(name); 35441da177e4SLinus Torvalds 35451da177e4SLinus Torvalds switch(nd.last_type) { 35461da177e4SLinus Torvalds case LAST_DOTDOT: 35471da177e4SLinus Torvalds error = -ENOTEMPTY; 35481da177e4SLinus Torvalds goto exit1; 35491da177e4SLinus Torvalds case LAST_DOT: 35501da177e4SLinus Torvalds error = -EINVAL; 35511da177e4SLinus Torvalds goto exit1; 35521da177e4SLinus Torvalds case LAST_ROOT: 35531da177e4SLinus Torvalds error = -EBUSY; 35541da177e4SLinus Torvalds goto exit1; 35551da177e4SLinus Torvalds } 35560612d9fbSOGAWA Hirofumi 35570612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 3558c30dabfeSJan Kara error = mnt_want_write(nd.path.mnt); 3559c30dabfeSJan Kara if (error) 3560c30dabfeSJan Kara goto exit1; 35610612d9fbSOGAWA Hirofumi 35624ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 356349705b77SChristoph Hellwig dentry = lookup_hash(&nd); 35641da177e4SLinus Torvalds error = PTR_ERR(dentry); 35656902d925SDave Hansen if (IS_ERR(dentry)) 35666902d925SDave Hansen goto exit2; 3567e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3568e6bc45d6STheodore Ts'o error = -ENOENT; 3569e6bc45d6STheodore Ts'o goto exit3; 3570e6bc45d6STheodore Ts'o } 3571be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 3572be6d3e56SKentaro Takeda if (error) 3573c30dabfeSJan Kara goto exit3; 35744ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 35750622753bSDave Hansen exit3: 35761da177e4SLinus Torvalds dput(dentry); 35776902d925SDave Hansen exit2: 35784ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3579c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 35801da177e4SLinus Torvalds exit1: 35811d957f9bSJan Blunck path_put(&nd.path); 35821da177e4SLinus Torvalds putname(name); 3583c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3584c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3585c6ee9206SJeff Layton goto retry; 3586c6ee9206SJeff Layton } 35871da177e4SLinus Torvalds return error; 35881da177e4SLinus Torvalds } 35891da177e4SLinus Torvalds 35903cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 35915590ff0dSUlrich Drepper { 35925590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 35935590ff0dSUlrich Drepper } 35945590ff0dSUlrich Drepper 3595b21996e3SJ. Bruce Fields /** 3596b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3597b21996e3SJ. Bruce Fields * @dir: parent directory 3598b21996e3SJ. Bruce Fields * @dentry: victim 3599b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3600b21996e3SJ. Bruce Fields * 3601b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3602b21996e3SJ. Bruce Fields * 3603b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3604b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3605b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3606b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3607b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3608b21996e3SJ. Bruce Fields * 3609b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3610b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3611b21996e3SJ. Bruce Fields * to be NFS exported. 3612b21996e3SJ. Bruce Fields */ 3613b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 36141da177e4SLinus Torvalds { 36159accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 36161da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 36171da177e4SLinus Torvalds 36181da177e4SLinus Torvalds if (error) 36191da177e4SLinus Torvalds return error; 36201da177e4SLinus Torvalds 3621acfa4380SAl Viro if (!dir->i_op->unlink) 36221da177e4SLinus Torvalds return -EPERM; 36231da177e4SLinus Torvalds 36249accbb97SJ. Bruce Fields mutex_lock(&target->i_mutex); 36251da177e4SLinus Torvalds if (d_mountpoint(dentry)) 36261da177e4SLinus Torvalds error = -EBUSY; 36271da177e4SLinus Torvalds else { 36281da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3629bec1052eSAl Viro if (!error) { 36305a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 36315a14696cSJ. Bruce Fields if (error) 3632b21996e3SJ. Bruce Fields goto out; 36331da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 3634bec1052eSAl Viro if (!error) 3635d83c49f3SAl Viro dont_mount(dentry); 3636bec1052eSAl Viro } 36371da177e4SLinus Torvalds } 3638b21996e3SJ. Bruce Fields out: 36399accbb97SJ. Bruce Fields mutex_unlock(&target->i_mutex); 36401da177e4SLinus Torvalds 36411da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 36421da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 36439accbb97SJ. Bruce Fields fsnotify_link_count(target); 36441da177e4SLinus Torvalds d_delete(dentry); 36451da177e4SLinus Torvalds } 36460eeca283SRobert Love 36471da177e4SLinus Torvalds return error; 36481da177e4SLinus Torvalds } 36491da177e4SLinus Torvalds 36501da177e4SLinus Torvalds /* 36511da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 36521b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 36531da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 36541da177e4SLinus Torvalds * while waiting on the I/O. 36551da177e4SLinus Torvalds */ 36565590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 36571da177e4SLinus Torvalds { 36582ad94ae6SAl Viro int error; 365991a27b2aSJeff Layton struct filename *name; 36601da177e4SLinus Torvalds struct dentry *dentry; 36611da177e4SLinus Torvalds struct nameidata nd; 36621da177e4SLinus Torvalds struct inode *inode = NULL; 3663b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 36645d18f813SJeff Layton unsigned int lookup_flags = 0; 36655d18f813SJeff Layton retry: 36665d18f813SJeff Layton name = user_path_parent(dfd, pathname, &nd, lookup_flags); 366791a27b2aSJeff Layton if (IS_ERR(name)) 366891a27b2aSJeff Layton return PTR_ERR(name); 36692ad94ae6SAl Viro 36701da177e4SLinus Torvalds error = -EISDIR; 36711da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 36721da177e4SLinus Torvalds goto exit1; 36730612d9fbSOGAWA Hirofumi 36740612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 3675c30dabfeSJan Kara error = mnt_want_write(nd.path.mnt); 3676c30dabfeSJan Kara if (error) 3677c30dabfeSJan Kara goto exit1; 3678b21996e3SJ. Bruce Fields retry_deleg: 36794ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 368049705b77SChristoph Hellwig dentry = lookup_hash(&nd); 36811da177e4SLinus Torvalds error = PTR_ERR(dentry); 36821da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 36831da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 368450338b88STörök Edwin if (nd.last.name[nd.last.len]) 368550338b88STörök Edwin goto slashes; 36861da177e4SLinus Torvalds inode = dentry->d_inode; 3687b18825a7SDavid Howells if (d_is_negative(dentry)) 3688e6bc45d6STheodore Ts'o goto slashes; 36897de9c6eeSAl Viro ihold(inode); 3690be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 3691be6d3e56SKentaro Takeda if (error) 3692c30dabfeSJan Kara goto exit2; 3693b21996e3SJ. Bruce Fields error = vfs_unlink(nd.path.dentry->d_inode, dentry, &delegated_inode); 36941da177e4SLinus Torvalds exit2: 36951da177e4SLinus Torvalds dput(dentry); 36961da177e4SLinus Torvalds } 36974ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 36981da177e4SLinus Torvalds if (inode) 36991da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3700b21996e3SJ. Bruce Fields inode = NULL; 3701b21996e3SJ. Bruce Fields if (delegated_inode) { 37025a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3703b21996e3SJ. Bruce Fields if (!error) 3704b21996e3SJ. Bruce Fields goto retry_deleg; 3705b21996e3SJ. Bruce Fields } 3706c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 37071da177e4SLinus Torvalds exit1: 37081d957f9bSJan Blunck path_put(&nd.path); 37091da177e4SLinus Torvalds putname(name); 37105d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 37115d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 37125d18f813SJeff Layton inode = NULL; 37135d18f813SJeff Layton goto retry; 37145d18f813SJeff Layton } 37151da177e4SLinus Torvalds return error; 37161da177e4SLinus Torvalds 37171da177e4SLinus Torvalds slashes: 3718b18825a7SDavid Howells if (d_is_negative(dentry)) 3719b18825a7SDavid Howells error = -ENOENT; 3720b18825a7SDavid Howells else if (d_is_directory(dentry) || d_is_autodir(dentry)) 3721b18825a7SDavid Howells error = -EISDIR; 3722b18825a7SDavid Howells else 3723b18825a7SDavid Howells error = -ENOTDIR; 37241da177e4SLinus Torvalds goto exit2; 37251da177e4SLinus Torvalds } 37261da177e4SLinus Torvalds 37272e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 37285590ff0dSUlrich Drepper { 37295590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 37305590ff0dSUlrich Drepper return -EINVAL; 37315590ff0dSUlrich Drepper 37325590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 37335590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 37345590ff0dSUlrich Drepper 37355590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 37365590ff0dSUlrich Drepper } 37375590ff0dSUlrich Drepper 37383480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 37395590ff0dSUlrich Drepper { 37405590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 37415590ff0dSUlrich Drepper } 37425590ff0dSUlrich Drepper 3743db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 37441da177e4SLinus Torvalds { 3745a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 37461da177e4SLinus Torvalds 37471da177e4SLinus Torvalds if (error) 37481da177e4SLinus Torvalds return error; 37491da177e4SLinus Torvalds 3750acfa4380SAl Viro if (!dir->i_op->symlink) 37511da177e4SLinus Torvalds return -EPERM; 37521da177e4SLinus Torvalds 37531da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 37541da177e4SLinus Torvalds if (error) 37551da177e4SLinus Torvalds return error; 37561da177e4SLinus Torvalds 37571da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3758a74574aaSStephen Smalley if (!error) 3759f38aa942SAmy Griffis fsnotify_create(dir, dentry); 37601da177e4SLinus Torvalds return error; 37611da177e4SLinus Torvalds } 37621da177e4SLinus Torvalds 37632e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 37642e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 37651da177e4SLinus Torvalds { 37662ad94ae6SAl Viro int error; 376791a27b2aSJeff Layton struct filename *from; 37686902d925SDave Hansen struct dentry *dentry; 3769dae6ad8fSAl Viro struct path path; 3770f46d3567SJeff Layton unsigned int lookup_flags = 0; 37711da177e4SLinus Torvalds 37721da177e4SLinus Torvalds from = getname(oldname); 37731da177e4SLinus Torvalds if (IS_ERR(from)) 37741da177e4SLinus Torvalds return PTR_ERR(from); 3775f46d3567SJeff Layton retry: 3776f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 37771da177e4SLinus Torvalds error = PTR_ERR(dentry); 37786902d925SDave Hansen if (IS_ERR(dentry)) 3779dae6ad8fSAl Viro goto out_putname; 37806902d925SDave Hansen 378191a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3782a8104a9fSAl Viro if (!error) 378391a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3784921a1650SAl Viro done_path_create(&path, dentry); 3785f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 3786f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 3787f46d3567SJeff Layton goto retry; 3788f46d3567SJeff Layton } 37896902d925SDave Hansen out_putname: 37901da177e4SLinus Torvalds putname(from); 37911da177e4SLinus Torvalds return error; 37921da177e4SLinus Torvalds } 37931da177e4SLinus Torvalds 37943480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 37955590ff0dSUlrich Drepper { 37965590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 37975590ff0dSUlrich Drepper } 37985590ff0dSUlrich Drepper 3799146a8595SJ. Bruce Fields /** 3800146a8595SJ. Bruce Fields * vfs_link - create a new link 3801146a8595SJ. Bruce Fields * @old_dentry: object to be linked 3802146a8595SJ. Bruce Fields * @dir: new parent 3803146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 3804146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 3805146a8595SJ. Bruce Fields * 3806146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 3807146a8595SJ. Bruce Fields * 3808146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 3809146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 3810146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 3811146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 3812146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 3813146a8595SJ. Bruce Fields * 3814146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3815146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3816146a8595SJ. Bruce Fields * to be NFS exported. 3817146a8595SJ. Bruce Fields */ 3818146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 38191da177e4SLinus Torvalds { 38201da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 38218de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 38221da177e4SLinus Torvalds int error; 38231da177e4SLinus Torvalds 38241da177e4SLinus Torvalds if (!inode) 38251da177e4SLinus Torvalds return -ENOENT; 38261da177e4SLinus Torvalds 3827a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 38281da177e4SLinus Torvalds if (error) 38291da177e4SLinus Torvalds return error; 38301da177e4SLinus Torvalds 38311da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 38321da177e4SLinus Torvalds return -EXDEV; 38331da177e4SLinus Torvalds 38341da177e4SLinus Torvalds /* 38351da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 38361da177e4SLinus Torvalds */ 38371da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 38381da177e4SLinus Torvalds return -EPERM; 3839acfa4380SAl Viro if (!dir->i_op->link) 38401da177e4SLinus Torvalds return -EPERM; 38417e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 38421da177e4SLinus Torvalds return -EPERM; 38431da177e4SLinus Torvalds 38441da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 38451da177e4SLinus Torvalds if (error) 38461da177e4SLinus Torvalds return error; 38471da177e4SLinus Torvalds 38487e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 3849aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 3850f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 3851aae8a97dSAneesh Kumar K.V error = -ENOENT; 38528de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 38538de52778SAl Viro error = -EMLINK; 3854146a8595SJ. Bruce Fields else { 3855146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 3856146a8595SJ. Bruce Fields if (!error) 38571da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 3858146a8595SJ. Bruce Fields } 3859f4e0c30cSAl Viro 3860f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 3861f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3862f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 3863f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3864f4e0c30cSAl Viro } 38657e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 3866e31e14ecSStephen Smalley if (!error) 38677e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 38681da177e4SLinus Torvalds return error; 38691da177e4SLinus Torvalds } 38701da177e4SLinus Torvalds 38711da177e4SLinus Torvalds /* 38721da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 38731da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 38741da177e4SLinus Torvalds * newname. --KAB 38751da177e4SLinus Torvalds * 38761da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 38771da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 38781da177e4SLinus Torvalds * and other special files. --ADM 38791da177e4SLinus Torvalds */ 38802e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 38812e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 38821da177e4SLinus Torvalds { 38831da177e4SLinus Torvalds struct dentry *new_dentry; 3884dae6ad8fSAl Viro struct path old_path, new_path; 3885146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 388611a7b371SAneesh Kumar K.V int how = 0; 38871da177e4SLinus Torvalds int error; 38881da177e4SLinus Torvalds 388911a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 3890c04030e1SUlrich Drepper return -EINVAL; 389111a7b371SAneesh Kumar K.V /* 3892f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 3893f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 3894f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 389511a7b371SAneesh Kumar K.V */ 3896f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 3897f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 3898f0cc6ffbSLinus Torvalds return -ENOENT; 389911a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 3900f0cc6ffbSLinus Torvalds } 3901c04030e1SUlrich Drepper 390211a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 390311a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 3904442e31caSJeff Layton retry: 390511a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 39061da177e4SLinus Torvalds if (error) 39072ad94ae6SAl Viro return error; 39082ad94ae6SAl Viro 3909442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 3910442e31caSJeff Layton (how & LOOKUP_REVAL)); 39111da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 39126902d925SDave Hansen if (IS_ERR(new_dentry)) 3913dae6ad8fSAl Viro goto out; 3914dae6ad8fSAl Viro 3915dae6ad8fSAl Viro error = -EXDEV; 3916dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 3917dae6ad8fSAl Viro goto out_dput; 3918800179c9SKees Cook error = may_linkat(&old_path); 3919800179c9SKees Cook if (unlikely(error)) 3920800179c9SKees Cook goto out_dput; 3921dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 3922be6d3e56SKentaro Takeda if (error) 3923a8104a9fSAl Viro goto out_dput; 3924146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 392575c3f29dSDave Hansen out_dput: 3926921a1650SAl Viro done_path_create(&new_path, new_dentry); 3927146a8595SJ. Bruce Fields if (delegated_inode) { 3928146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3929d22e6338SOleg Drokin if (!error) { 3930d22e6338SOleg Drokin path_put(&old_path); 3931146a8595SJ. Bruce Fields goto retry; 3932146a8595SJ. Bruce Fields } 3933d22e6338SOleg Drokin } 3934442e31caSJeff Layton if (retry_estale(error, how)) { 3935d22e6338SOleg Drokin path_put(&old_path); 3936442e31caSJeff Layton how |= LOOKUP_REVAL; 3937442e31caSJeff Layton goto retry; 3938442e31caSJeff Layton } 39391da177e4SLinus Torvalds out: 39402d8f3038SAl Viro path_put(&old_path); 39411da177e4SLinus Torvalds 39421da177e4SLinus Torvalds return error; 39431da177e4SLinus Torvalds } 39441da177e4SLinus Torvalds 39453480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 39465590ff0dSUlrich Drepper { 3947c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 39485590ff0dSUlrich Drepper } 39495590ff0dSUlrich Drepper 39501da177e4SLinus Torvalds /* 39511da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 39521da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 39531da177e4SLinus Torvalds * Problems: 39541da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 39551da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 39561da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 3957a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 39581da177e4SLinus Torvalds * story. 39596cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 39606cedba89SJ. Bruce Fields * and source (if it is not a directory). 39611b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 39621da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 39631da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 3964a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 39651da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 39661da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 39671da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 3968a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 39691da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 39701da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 39711da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 3972e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 39731b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 39741da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 3975c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 39761da177e4SLinus Torvalds * locking]. 39771da177e4SLinus Torvalds */ 397875c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 39791da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 39801da177e4SLinus Torvalds { 39811da177e4SLinus Torvalds int error = 0; 39829055cba7SSage Weil struct inode *target = new_dentry->d_inode; 39838de52778SAl Viro unsigned max_links = new_dir->i_sb->s_max_links; 39841da177e4SLinus Torvalds 39851da177e4SLinus Torvalds /* 39861da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 39871da177e4SLinus Torvalds * we'll need to flip '..'. 39881da177e4SLinus Torvalds */ 39891da177e4SLinus Torvalds if (new_dir != old_dir) { 3990f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 39911da177e4SLinus Torvalds if (error) 39921da177e4SLinus Torvalds return error; 39931da177e4SLinus Torvalds } 39941da177e4SLinus Torvalds 39951da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 39961da177e4SLinus Torvalds if (error) 39971da177e4SLinus Torvalds return error; 39981da177e4SLinus Torvalds 39991d2ef590SAl Viro dget(new_dentry); 4000d83c49f3SAl Viro if (target) 40011b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 40029055cba7SSage Weil 40031da177e4SLinus Torvalds error = -EBUSY; 40049055cba7SSage Weil if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) 40059055cba7SSage Weil goto out; 40069055cba7SSage Weil 40078de52778SAl Viro error = -EMLINK; 40088de52778SAl Viro if (max_links && !target && new_dir != old_dir && 40098de52778SAl Viro new_dir->i_nlink >= max_links) 40108de52778SAl Viro goto out; 40118de52778SAl Viro 40123cebde24SSage Weil if (target) 40133cebde24SSage Weil shrink_dcache_parent(new_dentry); 40141da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 40159055cba7SSage Weil if (error) 40169055cba7SSage Weil goto out; 40179055cba7SSage Weil 40181da177e4SLinus Torvalds if (target) { 40191da177e4SLinus Torvalds target->i_flags |= S_DEAD; 4020d83c49f3SAl Viro dont_mount(new_dentry); 4021d83c49f3SAl Viro } 40229055cba7SSage Weil out: 40239055cba7SSage Weil if (target) 40241b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 40251d2ef590SAl Viro dput(new_dentry); 4026e31e14ecSStephen Smalley if (!error) 4027349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 40281da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 40291da177e4SLinus Torvalds return error; 40301da177e4SLinus Torvalds } 40311da177e4SLinus Torvalds 403275c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 40338e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 40348e6d782cSJ. Bruce Fields struct inode **delegated_inode) 40351da177e4SLinus Torvalds { 403651892bbbSSage Weil struct inode *target = new_dentry->d_inode; 40376cedba89SJ. Bruce Fields struct inode *source = old_dentry->d_inode; 40381da177e4SLinus Torvalds int error; 40391da177e4SLinus Torvalds 40401da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 40411da177e4SLinus Torvalds if (error) 40421da177e4SLinus Torvalds return error; 40431da177e4SLinus Torvalds 40441da177e4SLinus Torvalds dget(new_dentry); 40456cedba89SJ. Bruce Fields lock_two_nondirectories(source, target); 404651892bbbSSage Weil 40471da177e4SLinus Torvalds error = -EBUSY; 404851892bbbSSage Weil if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 404951892bbbSSage Weil goto out; 405051892bbbSSage Weil 40518e6d782cSJ. Bruce Fields error = try_break_deleg(source, delegated_inode); 40528e6d782cSJ. Bruce Fields if (error) 40538e6d782cSJ. Bruce Fields goto out; 40548e6d782cSJ. Bruce Fields if (target) { 40558e6d782cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 40568e6d782cSJ. Bruce Fields if (error) 40578e6d782cSJ. Bruce Fields goto out; 40588e6d782cSJ. Bruce Fields } 40591da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 406051892bbbSSage Weil if (error) 406151892bbbSSage Weil goto out; 406251892bbbSSage Weil 4063bec1052eSAl Viro if (target) 4064d83c49f3SAl Viro dont_mount(new_dentry); 4065349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 40661da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 406751892bbbSSage Weil out: 40686cedba89SJ. Bruce Fields unlock_two_nondirectories(source, target); 40691da177e4SLinus Torvalds dput(new_dentry); 40701da177e4SLinus Torvalds return error; 40711da177e4SLinus Torvalds } 40721da177e4SLinus Torvalds 40738e6d782cSJ. Bruce Fields /** 40748e6d782cSJ. Bruce Fields * vfs_rename - rename a filesystem object 40758e6d782cSJ. Bruce Fields * @old_dir: parent of source 40768e6d782cSJ. Bruce Fields * @old_dentry: source 40778e6d782cSJ. Bruce Fields * @new_dir: parent of destination 40788e6d782cSJ. Bruce Fields * @new_dentry: destination 40798e6d782cSJ. Bruce Fields * @delegated_inode: returns an inode needing a delegation break 40808e6d782cSJ. Bruce Fields * 40818e6d782cSJ. Bruce Fields * The caller must hold multiple mutexes--see lock_rename()). 40828e6d782cSJ. Bruce Fields * 40838e6d782cSJ. Bruce Fields * If vfs_rename discovers a delegation in need of breaking at either 40848e6d782cSJ. Bruce Fields * the source or destination, it will return -EWOULDBLOCK and return a 40858e6d782cSJ. Bruce Fields * reference to the inode in delegated_inode. The caller should then 40868e6d782cSJ. Bruce Fields * break the delegation and retry. Because breaking a delegation may 40878e6d782cSJ. Bruce Fields * take a long time, the caller should drop all locks before doing 40888e6d782cSJ. Bruce Fields * so. 40898e6d782cSJ. Bruce Fields * 40908e6d782cSJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 40918e6d782cSJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 40928e6d782cSJ. Bruce Fields * to be NFS exported. 40938e6d782cSJ. Bruce Fields */ 40941da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 40958e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 40968e6d782cSJ. Bruce Fields struct inode **delegated_inode) 40971da177e4SLinus Torvalds { 40981da177e4SLinus Torvalds int error; 4099b18825a7SDavid Howells int is_dir = d_is_directory(old_dentry) || d_is_autodir(old_dentry); 410059b0df21SEric Paris const unsigned char *old_name; 41011da177e4SLinus Torvalds 41021da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 41031da177e4SLinus Torvalds return 0; 41041da177e4SLinus Torvalds 41051da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 41061da177e4SLinus Torvalds if (error) 41071da177e4SLinus Torvalds return error; 41081da177e4SLinus Torvalds 41091da177e4SLinus Torvalds if (!new_dentry->d_inode) 4110a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 41111da177e4SLinus Torvalds else 41121da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 41131da177e4SLinus Torvalds if (error) 41141da177e4SLinus Torvalds return error; 41151da177e4SLinus Torvalds 4116acfa4380SAl Viro if (!old_dir->i_op->rename) 41171da177e4SLinus Torvalds return -EPERM; 41181da177e4SLinus Torvalds 41190eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 41200eeca283SRobert Love 41211da177e4SLinus Torvalds if (is_dir) 41221da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 41231da177e4SLinus Torvalds else 41248e6d782cSJ. Bruce Fields error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry,delegated_inode); 4125123df294SAl Viro if (!error) 4126123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 41275a190ae6SAl Viro new_dentry->d_inode, old_dentry); 41280eeca283SRobert Love fsnotify_oldname_free(old_name); 41290eeca283SRobert Love 41301da177e4SLinus Torvalds return error; 41311da177e4SLinus Torvalds } 41321da177e4SLinus Torvalds 41332e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 41342e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 41351da177e4SLinus Torvalds { 41361da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 41371da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 41381da177e4SLinus Torvalds struct dentry *trap; 41391da177e4SLinus Torvalds struct nameidata oldnd, newnd; 41408e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 414191a27b2aSJeff Layton struct filename *from; 414291a27b2aSJeff Layton struct filename *to; 4143c6a94284SJeff Layton unsigned int lookup_flags = 0; 4144c6a94284SJeff Layton bool should_retry = false; 41452ad94ae6SAl Viro int error; 4146c6a94284SJeff Layton retry: 4147c6a94284SJeff Layton from = user_path_parent(olddfd, oldname, &oldnd, lookup_flags); 414891a27b2aSJeff Layton if (IS_ERR(from)) { 414991a27b2aSJeff Layton error = PTR_ERR(from); 41501da177e4SLinus Torvalds goto exit; 415191a27b2aSJeff Layton } 41521da177e4SLinus Torvalds 4153c6a94284SJeff Layton to = user_path_parent(newdfd, newname, &newnd, lookup_flags); 415491a27b2aSJeff Layton if (IS_ERR(to)) { 415591a27b2aSJeff Layton error = PTR_ERR(to); 41561da177e4SLinus Torvalds goto exit1; 415791a27b2aSJeff Layton } 41581da177e4SLinus Torvalds 41591da177e4SLinus Torvalds error = -EXDEV; 41604ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 41611da177e4SLinus Torvalds goto exit2; 41621da177e4SLinus Torvalds 41634ac91378SJan Blunck old_dir = oldnd.path.dentry; 41641da177e4SLinus Torvalds error = -EBUSY; 41651da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 41661da177e4SLinus Torvalds goto exit2; 41671da177e4SLinus Torvalds 41684ac91378SJan Blunck new_dir = newnd.path.dentry; 41691da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 41701da177e4SLinus Torvalds goto exit2; 41711da177e4SLinus Torvalds 4172c30dabfeSJan Kara error = mnt_want_write(oldnd.path.mnt); 4173c30dabfeSJan Kara if (error) 4174c30dabfeSJan Kara goto exit2; 4175c30dabfeSJan Kara 41760612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 41770612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 41784e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 41790612d9fbSOGAWA Hirofumi 41808e6d782cSJ. Bruce Fields retry_deleg: 41811da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 41821da177e4SLinus Torvalds 418349705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 41841da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 41851da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 41861da177e4SLinus Torvalds goto exit3; 41871da177e4SLinus Torvalds /* source must exist */ 41881da177e4SLinus Torvalds error = -ENOENT; 4189b18825a7SDavid Howells if (d_is_negative(old_dentry)) 41901da177e4SLinus Torvalds goto exit4; 41911da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 4192b18825a7SDavid Howells if (!d_is_directory(old_dentry) && !d_is_autodir(old_dentry)) { 41931da177e4SLinus Torvalds error = -ENOTDIR; 41941da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 41951da177e4SLinus Torvalds goto exit4; 41961da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 41971da177e4SLinus Torvalds goto exit4; 41981da177e4SLinus Torvalds } 41991da177e4SLinus Torvalds /* source should not be ancestor of target */ 42001da177e4SLinus Torvalds error = -EINVAL; 42011da177e4SLinus Torvalds if (old_dentry == trap) 42021da177e4SLinus Torvalds goto exit4; 420349705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 42041da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 42051da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 42061da177e4SLinus Torvalds goto exit4; 42071da177e4SLinus Torvalds /* target should not be an ancestor of source */ 42081da177e4SLinus Torvalds error = -ENOTEMPTY; 42091da177e4SLinus Torvalds if (new_dentry == trap) 42101da177e4SLinus Torvalds goto exit5; 42111da177e4SLinus Torvalds 4212be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 4213be6d3e56SKentaro Takeda &newnd.path, new_dentry); 4214be6d3e56SKentaro Takeda if (error) 4215c30dabfeSJan Kara goto exit5; 42161da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 42178e6d782cSJ. Bruce Fields new_dir->d_inode, new_dentry, 42188e6d782cSJ. Bruce Fields &delegated_inode); 42191da177e4SLinus Torvalds exit5: 42201da177e4SLinus Torvalds dput(new_dentry); 42211da177e4SLinus Torvalds exit4: 42221da177e4SLinus Torvalds dput(old_dentry); 42231da177e4SLinus Torvalds exit3: 42241da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 42258e6d782cSJ. Bruce Fields if (delegated_inode) { 42268e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 42278e6d782cSJ. Bruce Fields if (!error) 42288e6d782cSJ. Bruce Fields goto retry_deleg; 42298e6d782cSJ. Bruce Fields } 4230c30dabfeSJan Kara mnt_drop_write(oldnd.path.mnt); 42311da177e4SLinus Torvalds exit2: 4232c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4233c6a94284SJeff Layton should_retry = true; 42341d957f9bSJan Blunck path_put(&newnd.path); 42352ad94ae6SAl Viro putname(to); 42361da177e4SLinus Torvalds exit1: 42371d957f9bSJan Blunck path_put(&oldnd.path); 42381da177e4SLinus Torvalds putname(from); 4239c6a94284SJeff Layton if (should_retry) { 4240c6a94284SJeff Layton should_retry = false; 4241c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4242c6a94284SJeff Layton goto retry; 4243c6a94284SJeff Layton } 42442ad94ae6SAl Viro exit: 42451da177e4SLinus Torvalds return error; 42461da177e4SLinus Torvalds } 42471da177e4SLinus Torvalds 4248a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 42495590ff0dSUlrich Drepper { 42505590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 42515590ff0dSUlrich Drepper } 42525590ff0dSUlrich Drepper 42531da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 42541da177e4SLinus Torvalds { 42551da177e4SLinus Torvalds int len; 42561da177e4SLinus Torvalds 42571da177e4SLinus Torvalds len = PTR_ERR(link); 42581da177e4SLinus Torvalds if (IS_ERR(link)) 42591da177e4SLinus Torvalds goto out; 42601da177e4SLinus Torvalds 42611da177e4SLinus Torvalds len = strlen(link); 42621da177e4SLinus Torvalds if (len > (unsigned) buflen) 42631da177e4SLinus Torvalds len = buflen; 42641da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 42651da177e4SLinus Torvalds len = -EFAULT; 42661da177e4SLinus Torvalds out: 42671da177e4SLinus Torvalds return len; 42681da177e4SLinus Torvalds } 42691da177e4SLinus Torvalds 42701da177e4SLinus Torvalds /* 42711da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 42721da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 42731da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 42741da177e4SLinus Torvalds */ 42751da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 42761da177e4SLinus Torvalds { 42771da177e4SLinus Torvalds struct nameidata nd; 4278cc314eefSLinus Torvalds void *cookie; 4279694a1764SMarcin Slusarz int res; 4280cc314eefSLinus Torvalds 42811da177e4SLinus Torvalds nd.depth = 0; 4282cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 4283694a1764SMarcin Slusarz if (IS_ERR(cookie)) 4284694a1764SMarcin Slusarz return PTR_ERR(cookie); 4285694a1764SMarcin Slusarz 4286694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 42871da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 4288cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 4289694a1764SMarcin Slusarz return res; 42901da177e4SLinus Torvalds } 42911da177e4SLinus Torvalds 42921da177e4SLinus Torvalds /* get the link contents into pagecache */ 42931da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 42941da177e4SLinus Torvalds { 4295ebd09abbSDuane Griffin char *kaddr; 42961da177e4SLinus Torvalds struct page *page; 42971da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 4298090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 42991da177e4SLinus Torvalds if (IS_ERR(page)) 43006fe6900eSNick Piggin return (char*)page; 43011da177e4SLinus Torvalds *ppage = page; 4302ebd09abbSDuane Griffin kaddr = kmap(page); 4303ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 4304ebd09abbSDuane Griffin return kaddr; 43051da177e4SLinus Torvalds } 43061da177e4SLinus Torvalds 43071da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 43081da177e4SLinus Torvalds { 43091da177e4SLinus Torvalds struct page *page = NULL; 43101da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 43111da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 43121da177e4SLinus Torvalds if (page) { 43131da177e4SLinus Torvalds kunmap(page); 43141da177e4SLinus Torvalds page_cache_release(page); 43151da177e4SLinus Torvalds } 43161da177e4SLinus Torvalds return res; 43171da177e4SLinus Torvalds } 43181da177e4SLinus Torvalds 4319cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 43201da177e4SLinus Torvalds { 4321cc314eefSLinus Torvalds struct page *page = NULL; 43221da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 4323cc314eefSLinus Torvalds return page; 43241da177e4SLinus Torvalds } 43251da177e4SLinus Torvalds 4326cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 43271da177e4SLinus Torvalds { 4328cc314eefSLinus Torvalds struct page *page = cookie; 4329cc314eefSLinus Torvalds 4330cc314eefSLinus Torvalds if (page) { 43311da177e4SLinus Torvalds kunmap(page); 43321da177e4SLinus Torvalds page_cache_release(page); 43331da177e4SLinus Torvalds } 43341da177e4SLinus Torvalds } 43351da177e4SLinus Torvalds 433654566b2cSNick Piggin /* 433754566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 433854566b2cSNick Piggin */ 433954566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 43401da177e4SLinus Torvalds { 43411da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 43420adb25d2SKirill Korotaev struct page *page; 4343afddba49SNick Piggin void *fsdata; 4344beb497abSDmitriy Monakhov int err; 43451da177e4SLinus Torvalds char *kaddr; 434654566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 434754566b2cSNick Piggin if (nofs) 434854566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 43491da177e4SLinus Torvalds 43507e53cac4SNeilBrown retry: 4351afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 435254566b2cSNick Piggin flags, &page, &fsdata); 43531da177e4SLinus Torvalds if (err) 4354afddba49SNick Piggin goto fail; 4355afddba49SNick Piggin 4356e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 43571da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 4358e8e3c3d6SCong Wang kunmap_atomic(kaddr); 4359afddba49SNick Piggin 4360afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4361afddba49SNick Piggin page, fsdata); 43621da177e4SLinus Torvalds if (err < 0) 43631da177e4SLinus Torvalds goto fail; 4364afddba49SNick Piggin if (err < len-1) 4365afddba49SNick Piggin goto retry; 4366afddba49SNick Piggin 43671da177e4SLinus Torvalds mark_inode_dirty(inode); 43681da177e4SLinus Torvalds return 0; 43691da177e4SLinus Torvalds fail: 43701da177e4SLinus Torvalds return err; 43711da177e4SLinus Torvalds } 43721da177e4SLinus Torvalds 43730adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 43740adb25d2SKirill Korotaev { 43750adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 437654566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 43770adb25d2SKirill Korotaev } 43780adb25d2SKirill Korotaev 437992e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 43801da177e4SLinus Torvalds .readlink = generic_readlink, 43811da177e4SLinus Torvalds .follow_link = page_follow_link_light, 43821da177e4SLinus Torvalds .put_link = page_put_link, 43831da177e4SLinus Torvalds }; 43841da177e4SLinus Torvalds 43852d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 4386cc53ce53SDavid Howells EXPORT_SYMBOL(follow_down_one); 43871da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 43881da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 4389f6d2ac5cSAl Viro EXPORT_SYMBOL(get_write_access); /* nfsd */ 43901da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 43911da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 43921da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 43931da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 43941da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 43950adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 43961da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 43971da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4398d1811465SAl Viro EXPORT_SYMBOL(kern_path); 439916f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 4400f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 44011da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 44021da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 44031da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 44041da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 44051da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 44061da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 44071da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 44081da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 44091da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 44101da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 44111da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 44121da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 44131da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 4414