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 */ 1201fa1e7f6SAndy Whitcroft static char *getname_flags(const char __user *filename, int flags, int *empty) 1211da177e4SLinus Torvalds { 1223f9f0aa6SLinus Torvalds char *result = __getname(), *err; 1233f9f0aa6SLinus Torvalds int len; 1241da177e4SLinus Torvalds 1253f9f0aa6SLinus Torvalds if (unlikely(!result)) 1264043cde8SEric Paris return ERR_PTR(-ENOMEM); 1271da177e4SLinus Torvalds 1283f9f0aa6SLinus Torvalds len = strncpy_from_user(result, filename, PATH_MAX); 1293f9f0aa6SLinus Torvalds err = ERR_PTR(len); 1303f9f0aa6SLinus Torvalds if (unlikely(len < 0)) 1313f9f0aa6SLinus Torvalds goto error; 1323f9f0aa6SLinus Torvalds 1333f9f0aa6SLinus Torvalds /* The empty path is special. */ 1343f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1353f9f0aa6SLinus Torvalds if (empty) 1361fa1e7f6SAndy Whitcroft *empty = 1; 1373f9f0aa6SLinus Torvalds err = ERR_PTR(-ENOENT); 1383f9f0aa6SLinus Torvalds if (!(flags & LOOKUP_EMPTY)) 1393f9f0aa6SLinus Torvalds goto error; 1401da177e4SLinus Torvalds } 1413f9f0aa6SLinus Torvalds 1423f9f0aa6SLinus Torvalds err = ERR_PTR(-ENAMETOOLONG); 1433f9f0aa6SLinus Torvalds if (likely(len < PATH_MAX)) { 1441da177e4SLinus Torvalds audit_getname(result); 1451da177e4SLinus Torvalds return result; 1461da177e4SLinus Torvalds } 1471da177e4SLinus Torvalds 1483f9f0aa6SLinus Torvalds error: 1493f9f0aa6SLinus Torvalds __putname(result); 1503f9f0aa6SLinus Torvalds return err; 1513f9f0aa6SLinus Torvalds } 1523f9f0aa6SLinus Torvalds 153f52e0c11SAl Viro char *getname(const char __user * filename) 154f52e0c11SAl Viro { 155f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 156f52e0c11SAl Viro } 157f52e0c11SAl Viro 1581da177e4SLinus Torvalds #ifdef CONFIG_AUDITSYSCALL 1591da177e4SLinus Torvalds void putname(const char *name) 1601da177e4SLinus Torvalds { 1615ac3a9c2SAl Viro if (unlikely(!audit_dummy_context())) 1621da177e4SLinus Torvalds audit_putname(name); 1631da177e4SLinus Torvalds else 1641da177e4SLinus Torvalds __putname(name); 1651da177e4SLinus Torvalds } 1661da177e4SLinus Torvalds EXPORT_SYMBOL(putname); 1671da177e4SLinus Torvalds #endif 1681da177e4SLinus Torvalds 169e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 170e77819e5SLinus Torvalds { 17184635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 172e77819e5SLinus Torvalds struct posix_acl *acl; 173e77819e5SLinus Torvalds 174e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 1753567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 1763567866bSAl Viro if (!acl) 177e77819e5SLinus Torvalds return -EAGAIN; 1783567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 1793567866bSAl Viro if (acl == ACL_NOT_CACHED) 180e77819e5SLinus Torvalds return -ECHILD; 181206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 182e77819e5SLinus Torvalds } 183e77819e5SLinus Torvalds 184e77819e5SLinus Torvalds acl = get_cached_acl(inode, ACL_TYPE_ACCESS); 185e77819e5SLinus Torvalds 186e77819e5SLinus Torvalds /* 1874e34e719SChristoph Hellwig * A filesystem can force a ACL callback by just never filling the 1884e34e719SChristoph Hellwig * ACL cache. But normally you'd fill the cache either at inode 1894e34e719SChristoph Hellwig * instantiation time, or on the first ->get_acl call. 190e77819e5SLinus Torvalds * 1914e34e719SChristoph Hellwig * If the filesystem doesn't have a get_acl() function at all, we'll 1924e34e719SChristoph Hellwig * just create the negative cache entry. 193e77819e5SLinus Torvalds */ 194e77819e5SLinus Torvalds if (acl == ACL_NOT_CACHED) { 1954e34e719SChristoph Hellwig if (inode->i_op->get_acl) { 1964e34e719SChristoph Hellwig acl = inode->i_op->get_acl(inode, ACL_TYPE_ACCESS); 1974e34e719SChristoph Hellwig if (IS_ERR(acl)) 1984e34e719SChristoph Hellwig return PTR_ERR(acl); 1994e34e719SChristoph Hellwig } else { 200e77819e5SLinus Torvalds set_cached_acl(inode, ACL_TYPE_ACCESS, NULL); 201e77819e5SLinus Torvalds return -EAGAIN; 202e77819e5SLinus Torvalds } 2034e34e719SChristoph Hellwig } 204e77819e5SLinus Torvalds 205e77819e5SLinus Torvalds if (acl) { 206e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 207e77819e5SLinus Torvalds posix_acl_release(acl); 208e77819e5SLinus Torvalds return error; 209e77819e5SLinus Torvalds } 21084635d68SLinus Torvalds #endif 211e77819e5SLinus Torvalds 212e77819e5SLinus Torvalds return -EAGAIN; 213e77819e5SLinus Torvalds } 214e77819e5SLinus Torvalds 2155909ccaaSLinus Torvalds /* 216948409c7SAndreas Gruenbacher * This does the basic permission checking 2175909ccaaSLinus Torvalds */ 2187e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2195909ccaaSLinus Torvalds { 22026cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2215909ccaaSLinus Torvalds 2228e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2235909ccaaSLinus Torvalds mode >>= 6; 2245909ccaaSLinus Torvalds else { 225e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2267e40145eSAl Viro int error = check_acl(inode, mask); 2275909ccaaSLinus Torvalds if (error != -EAGAIN) 2285909ccaaSLinus Torvalds return error; 2295909ccaaSLinus Torvalds } 2305909ccaaSLinus Torvalds 2315909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 2325909ccaaSLinus Torvalds mode >>= 3; 2335909ccaaSLinus Torvalds } 2345909ccaaSLinus Torvalds 2355909ccaaSLinus Torvalds /* 2365909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 2375909ccaaSLinus Torvalds */ 2389c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 2395909ccaaSLinus Torvalds return 0; 2405909ccaaSLinus Torvalds return -EACCES; 2415909ccaaSLinus Torvalds } 2421da177e4SLinus Torvalds 2431da177e4SLinus Torvalds /** 2441da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 2451da177e4SLinus Torvalds * @inode: inode to check access rights for 2468fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 2471da177e4SLinus Torvalds * 2481da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 2491da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 2501da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 251b74c79e9SNick Piggin * are used for other things. 252b74c79e9SNick Piggin * 253b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 254b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 255b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 2561da177e4SLinus Torvalds */ 2572830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 2581da177e4SLinus Torvalds { 2595909ccaaSLinus Torvalds int ret; 2601da177e4SLinus Torvalds 2611da177e4SLinus Torvalds /* 262948409c7SAndreas Gruenbacher * Do the basic permission checks. 2631da177e4SLinus Torvalds */ 2647e40145eSAl Viro ret = acl_permission_check(inode, mask); 2655909ccaaSLinus Torvalds if (ret != -EACCES) 2665909ccaaSLinus Torvalds return ret; 2671da177e4SLinus Torvalds 268d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 269d594e7ecSAl Viro /* DACs are overridable for directories */ 2701a48e2acSEric W. Biederman if (inode_capable(inode, CAP_DAC_OVERRIDE)) 271d594e7ecSAl Viro return 0; 272d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 2731a48e2acSEric W. Biederman if (inode_capable(inode, CAP_DAC_READ_SEARCH)) 274d594e7ecSAl Viro return 0; 275d594e7ecSAl Viro return -EACCES; 276d594e7ecSAl Viro } 2771da177e4SLinus Torvalds /* 2781da177e4SLinus Torvalds * Read/write DACs are always overridable. 279d594e7ecSAl Viro * Executable DACs are overridable when there is 280d594e7ecSAl Viro * at least one exec bit set. 2811da177e4SLinus Torvalds */ 282d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 2831a48e2acSEric W. Biederman if (inode_capable(inode, CAP_DAC_OVERRIDE)) 2841da177e4SLinus Torvalds return 0; 2851da177e4SLinus Torvalds 2861da177e4SLinus Torvalds /* 2871da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 2881da177e4SLinus Torvalds */ 2897ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 290d594e7ecSAl Viro if (mask == MAY_READ) 2911a48e2acSEric W. Biederman if (inode_capable(inode, CAP_DAC_READ_SEARCH)) 2921da177e4SLinus Torvalds return 0; 2931da177e4SLinus Torvalds 2941da177e4SLinus Torvalds return -EACCES; 2951da177e4SLinus Torvalds } 2961da177e4SLinus Torvalds 2973ddcd056SLinus Torvalds /* 2983ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 2993ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3003ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3013ddcd056SLinus Torvalds * permission function, use the fast case". 3023ddcd056SLinus Torvalds */ 3033ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3043ddcd056SLinus Torvalds { 3053ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3063ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3073ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3083ddcd056SLinus Torvalds 3093ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3103ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3113ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3123ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3133ddcd056SLinus Torvalds } 3143ddcd056SLinus Torvalds return generic_permission(inode, mask); 3153ddcd056SLinus Torvalds } 3163ddcd056SLinus Torvalds 317cb23beb5SChristoph Hellwig /** 318cb23beb5SChristoph Hellwig * inode_permission - check for access rights to a given inode 319cb23beb5SChristoph Hellwig * @inode: inode to check permission on 3208fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 321cb23beb5SChristoph Hellwig * 322cb23beb5SChristoph Hellwig * Used to check for read/write/execute permissions on an inode. 323cb23beb5SChristoph Hellwig * We use "fsuid" for this, letting us set arbitrary permissions 324cb23beb5SChristoph Hellwig * for filesystem access without changing the "normal" uids which 325cb23beb5SChristoph Hellwig * are used for other things. 326948409c7SAndreas Gruenbacher * 327948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 328cb23beb5SChristoph Hellwig */ 329f419a2e3SAl Viro int inode_permission(struct inode *inode, int mask) 3301da177e4SLinus Torvalds { 331e6305c43SAl Viro int retval; 3321da177e4SLinus Torvalds 3333ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 33422590e41SMiklos Szeredi umode_t mode = inode->i_mode; 3351da177e4SLinus Torvalds 3361da177e4SLinus Torvalds /* 3371da177e4SLinus Torvalds * Nobody gets write access to a read-only fs. 3381da177e4SLinus Torvalds */ 3391da177e4SLinus Torvalds if (IS_RDONLY(inode) && 3401da177e4SLinus Torvalds (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 3411da177e4SLinus Torvalds return -EROFS; 3421da177e4SLinus Torvalds 3431da177e4SLinus Torvalds /* 3441da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 3451da177e4SLinus Torvalds */ 3461da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 3471da177e4SLinus Torvalds return -EACCES; 3481da177e4SLinus Torvalds } 3491da177e4SLinus Torvalds 3503ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 3511da177e4SLinus Torvalds if (retval) 3521da177e4SLinus Torvalds return retval; 3531da177e4SLinus Torvalds 35408ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 35508ce5f16SSerge E. Hallyn if (retval) 35608ce5f16SSerge E. Hallyn return retval; 35708ce5f16SSerge E. Hallyn 358d09ca739SEric Paris return security_inode_permission(inode, mask); 3591da177e4SLinus Torvalds } 3601da177e4SLinus Torvalds 361f4d6ff89SAl Viro /** 3625dd784d0SJan Blunck * path_get - get a reference to a path 3635dd784d0SJan Blunck * @path: path to get the reference to 3645dd784d0SJan Blunck * 3655dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 3665dd784d0SJan Blunck */ 3675dd784d0SJan Blunck void path_get(struct path *path) 3685dd784d0SJan Blunck { 3695dd784d0SJan Blunck mntget(path->mnt); 3705dd784d0SJan Blunck dget(path->dentry); 3715dd784d0SJan Blunck } 3725dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 3735dd784d0SJan Blunck 3745dd784d0SJan Blunck /** 3751d957f9bSJan Blunck * path_put - put a reference to a path 3761d957f9bSJan Blunck * @path: path to put the reference to 3771d957f9bSJan Blunck * 3781d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 3791d957f9bSJan Blunck */ 3801d957f9bSJan Blunck void path_put(struct path *path) 3811da177e4SLinus Torvalds { 3821d957f9bSJan Blunck dput(path->dentry); 3831d957f9bSJan Blunck mntput(path->mnt); 3841da177e4SLinus Torvalds } 3851d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 3861da177e4SLinus Torvalds 38719660af7SAl Viro /* 38831e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 38919660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 39019660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 39119660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 39219660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 39319660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 39419660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 39519660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 39631e6b01fSNick Piggin */ 39731e6b01fSNick Piggin 39831e6b01fSNick Piggin /** 39919660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 40019660af7SAl Viro * @nd: nameidata pathwalk data 40119660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 40239191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 40331e6b01fSNick Piggin * 40419660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 40519660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 40619660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 40731e6b01fSNick Piggin */ 40819660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 40931e6b01fSNick Piggin { 41031e6b01fSNick Piggin struct fs_struct *fs = current->fs; 41131e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 4125b6ca027SAl Viro int want_root = 0; 41331e6b01fSNick Piggin 41431e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 4155b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 4165b6ca027SAl Viro want_root = 1; 41731e6b01fSNick Piggin spin_lock(&fs->lock); 41831e6b01fSNick Piggin if (nd->root.mnt != fs->root.mnt || 41931e6b01fSNick Piggin nd->root.dentry != fs->root.dentry) 42031e6b01fSNick Piggin goto err_root; 42131e6b01fSNick Piggin } 42231e6b01fSNick Piggin spin_lock(&parent->d_lock); 42319660af7SAl Viro if (!dentry) { 42419660af7SAl Viro if (!__d_rcu_to_refcount(parent, nd->seq)) 42519660af7SAl Viro goto err_parent; 42619660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 42719660af7SAl Viro } else { 42894c0d4ecSAl Viro if (dentry->d_parent != parent) 42994c0d4ecSAl Viro goto err_parent; 43031e6b01fSNick Piggin spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); 43131e6b01fSNick Piggin if (!__d_rcu_to_refcount(dentry, nd->seq)) 43219660af7SAl Viro goto err_child; 43331e6b01fSNick Piggin /* 43419660af7SAl Viro * If the sequence check on the child dentry passed, then 43519660af7SAl Viro * the child has not been removed from its parent. This 43619660af7SAl Viro * means the parent dentry must be valid and able to take 43719660af7SAl Viro * a reference at this point. 43831e6b01fSNick Piggin */ 43931e6b01fSNick Piggin BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent); 44031e6b01fSNick Piggin BUG_ON(!parent->d_count); 44131e6b01fSNick Piggin parent->d_count++; 44231e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 44319660af7SAl Viro } 44431e6b01fSNick Piggin spin_unlock(&parent->d_lock); 4455b6ca027SAl Viro if (want_root) { 44631e6b01fSNick Piggin path_get(&nd->root); 44731e6b01fSNick Piggin spin_unlock(&fs->lock); 44831e6b01fSNick Piggin } 44931e6b01fSNick Piggin mntget(nd->path.mnt); 45031e6b01fSNick Piggin 45131e6b01fSNick Piggin rcu_read_unlock(); 452962830dfSAndi Kleen br_read_unlock(&vfsmount_lock); 45331e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 45431e6b01fSNick Piggin return 0; 45519660af7SAl Viro 45619660af7SAl Viro err_child: 45731e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 45819660af7SAl Viro err_parent: 45931e6b01fSNick Piggin spin_unlock(&parent->d_lock); 46031e6b01fSNick Piggin err_root: 4615b6ca027SAl Viro if (want_root) 46231e6b01fSNick Piggin spin_unlock(&fs->lock); 46331e6b01fSNick Piggin return -ECHILD; 46431e6b01fSNick Piggin } 46531e6b01fSNick Piggin 46631e6b01fSNick Piggin /** 467834f2a4aSTrond Myklebust * release_open_intent - free up open intent resources 468834f2a4aSTrond Myklebust * @nd: pointer to nameidata 469834f2a4aSTrond Myklebust */ 470834f2a4aSTrond Myklebust void release_open_intent(struct nameidata *nd) 471834f2a4aSTrond Myklebust { 4722dab5974SLinus Torvalds struct file *file = nd->intent.open.file; 4732dab5974SLinus Torvalds 4742dab5974SLinus Torvalds if (file && !IS_ERR(file)) { 4752dab5974SLinus Torvalds if (file->f_path.dentry == NULL) 4762dab5974SLinus Torvalds put_filp(file); 477834f2a4aSTrond Myklebust else 4782dab5974SLinus Torvalds fput(file); 4792dab5974SLinus Torvalds } 480834f2a4aSTrond Myklebust } 481834f2a4aSTrond Myklebust 482f60aef7eSAl Viro static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd) 48334286d66SNick Piggin { 484f60aef7eSAl Viro return dentry->d_op->d_revalidate(dentry, nd); 48534286d66SNick Piggin } 48634286d66SNick Piggin 4879f1fafeeSAl Viro /** 4889f1fafeeSAl Viro * complete_walk - successful completion of path walk 4899f1fafeeSAl Viro * @nd: pointer nameidata 49039159de2SJeff Layton * 4919f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 4929f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 4939f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 4949f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 4959f1fafeeSAl Viro * need to drop nd->path. 49639159de2SJeff Layton */ 4979f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 49839159de2SJeff Layton { 49916c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 50039159de2SJeff Layton int status; 50139159de2SJeff Layton 5029f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 5039f1fafeeSAl Viro nd->flags &= ~LOOKUP_RCU; 5049f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 5059f1fafeeSAl Viro nd->root.mnt = NULL; 5069f1fafeeSAl Viro spin_lock(&dentry->d_lock); 5079f1fafeeSAl Viro if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) { 5089f1fafeeSAl Viro spin_unlock(&dentry->d_lock); 5099f1fafeeSAl Viro rcu_read_unlock(); 510962830dfSAndi Kleen br_read_unlock(&vfsmount_lock); 5119f1fafeeSAl Viro return -ECHILD; 5129f1fafeeSAl Viro } 5139f1fafeeSAl Viro BUG_ON(nd->inode != dentry->d_inode); 5149f1fafeeSAl Viro spin_unlock(&dentry->d_lock); 5159f1fafeeSAl Viro mntget(nd->path.mnt); 5169f1fafeeSAl Viro rcu_read_unlock(); 517962830dfSAndi Kleen br_read_unlock(&vfsmount_lock); 5189f1fafeeSAl Viro } 5199f1fafeeSAl Viro 52016c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 52139159de2SJeff Layton return 0; 52239159de2SJeff Layton 52316c2cd71SAl Viro if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE))) 52416c2cd71SAl Viro return 0; 52516c2cd71SAl Viro 52616c2cd71SAl Viro if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))) 52716c2cd71SAl Viro return 0; 52816c2cd71SAl Viro 52916c2cd71SAl Viro /* Note: we do not d_invalidate() */ 53034286d66SNick Piggin status = d_revalidate(dentry, nd); 53139159de2SJeff Layton if (status > 0) 53239159de2SJeff Layton return 0; 53339159de2SJeff Layton 53416c2cd71SAl Viro if (!status) 53539159de2SJeff Layton status = -ESTALE; 53616c2cd71SAl Viro 5379f1fafeeSAl Viro path_put(&nd->path); 53839159de2SJeff Layton return status; 53939159de2SJeff Layton } 54039159de2SJeff Layton 5412a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 5422a737871SAl Viro { 543f7ad3c6bSMiklos Szeredi if (!nd->root.mnt) 544f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 5452a737871SAl Viro } 5462a737871SAl Viro 5476de88d72SAl Viro static int link_path_walk(const char *, struct nameidata *); 5486de88d72SAl Viro 54931e6b01fSNick Piggin static __always_inline void set_root_rcu(struct nameidata *nd) 55031e6b01fSNick Piggin { 55131e6b01fSNick Piggin if (!nd->root.mnt) { 55231e6b01fSNick Piggin struct fs_struct *fs = current->fs; 553c28cc364SNick Piggin unsigned seq; 554c28cc364SNick Piggin 555c28cc364SNick Piggin do { 556c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 55731e6b01fSNick Piggin nd->root = fs->root; 558c1530019STim Chen nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 559c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 56031e6b01fSNick Piggin } 56131e6b01fSNick Piggin } 56231e6b01fSNick Piggin 563f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 5641da177e4SLinus Torvalds { 56531e6b01fSNick Piggin int ret; 56631e6b01fSNick Piggin 5671da177e4SLinus Torvalds if (IS_ERR(link)) 5681da177e4SLinus Torvalds goto fail; 5691da177e4SLinus Torvalds 5701da177e4SLinus Torvalds if (*link == '/') { 5712a737871SAl Viro set_root(nd); 5721d957f9bSJan Blunck path_put(&nd->path); 5732a737871SAl Viro nd->path = nd->root; 5742a737871SAl Viro path_get(&nd->root); 57516c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 5761da177e4SLinus Torvalds } 57731e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 578b4091d5fSChristoph Hellwig 57931e6b01fSNick Piggin ret = link_path_walk(link, nd); 58031e6b01fSNick Piggin return ret; 5811da177e4SLinus Torvalds fail: 5821d957f9bSJan Blunck path_put(&nd->path); 5831da177e4SLinus Torvalds return PTR_ERR(link); 5841da177e4SLinus Torvalds } 5851da177e4SLinus Torvalds 5861d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 587051d3812SIan Kent { 588051d3812SIan Kent dput(path->dentry); 5894ac91378SJan Blunck if (path->mnt != nd->path.mnt) 590051d3812SIan Kent mntput(path->mnt); 591051d3812SIan Kent } 592051d3812SIan Kent 5937b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 5947b9337aaSNick Piggin struct nameidata *nd) 595051d3812SIan Kent { 59631e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 5974ac91378SJan Blunck dput(nd->path.dentry); 59831e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 5994ac91378SJan Blunck mntput(nd->path.mnt); 6009a229683SHuang Shijie } 60131e6b01fSNick Piggin nd->path.mnt = path->mnt; 6024ac91378SJan Blunck nd->path.dentry = path->dentry; 603051d3812SIan Kent } 604051d3812SIan Kent 605574197e0SAl Viro static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) 606574197e0SAl Viro { 607574197e0SAl Viro struct inode *inode = link->dentry->d_inode; 6086d7b5aaeSAl Viro if (inode->i_op->put_link) 609574197e0SAl Viro inode->i_op->put_link(link->dentry, nd, cookie); 610574197e0SAl Viro path_put(link); 611574197e0SAl Viro } 612574197e0SAl Viro 613def4af30SAl Viro static __always_inline int 614574197e0SAl Viro follow_link(struct path *link, struct nameidata *nd, void **p) 6151da177e4SLinus Torvalds { 6167b9337aaSNick Piggin struct dentry *dentry = link->dentry; 6176d7b5aaeSAl Viro int error; 6186d7b5aaeSAl Viro char *s; 6191da177e4SLinus Torvalds 620844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 621844a3917SAl Viro 6220e794589SAl Viro if (link->mnt == nd->path.mnt) 6230e794589SAl Viro mntget(link->mnt); 6240e794589SAl Viro 6256d7b5aaeSAl Viro error = -ELOOP; 6266d7b5aaeSAl Viro if (unlikely(current->total_link_count >= 40)) 6276d7b5aaeSAl Viro goto out_put_nd_path; 6286d7b5aaeSAl Viro 629574197e0SAl Viro cond_resched(); 630574197e0SAl Viro current->total_link_count++; 631574197e0SAl Viro 63268ac1234SAl Viro touch_atime(link); 6331da177e4SLinus Torvalds nd_set_link(nd, NULL); 634cd4e91d3SAl Viro 63536f3b4f6SAl Viro error = security_inode_follow_link(link->dentry, nd); 6366d7b5aaeSAl Viro if (error) 6376d7b5aaeSAl Viro goto out_put_nd_path; 63836f3b4f6SAl Viro 63986acdca1SAl Viro nd->last_type = LAST_BIND; 640def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 641def4af30SAl Viro error = PTR_ERR(*p); 6426d7b5aaeSAl Viro if (IS_ERR(*p)) 6436d7b5aaeSAl Viro goto out_put_link; 6446d7b5aaeSAl Viro 645cc314eefSLinus Torvalds error = 0; 6466d7b5aaeSAl Viro s = nd_get_link(nd); 6476d7b5aaeSAl Viro if (s) { 6481da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 6496d7b5aaeSAl Viro } else if (nd->last_type == LAST_BIND) { 65016c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 651b21041d0SAl Viro nd->inode = nd->path.dentry->d_inode; 652b21041d0SAl Viro if (nd->inode->i_op->follow_link) { 653bcda7652SAl Viro /* stepped on a _really_ weird one */ 654bcda7652SAl Viro path_put(&nd->path); 655bcda7652SAl Viro error = -ELOOP; 656bcda7652SAl Viro } 657bcda7652SAl Viro } 6586d7b5aaeSAl Viro if (unlikely(error)) 6596d7b5aaeSAl Viro put_link(nd, link, *p); 6606d7b5aaeSAl Viro 6616d7b5aaeSAl Viro return error; 6626d7b5aaeSAl Viro 6636d7b5aaeSAl Viro out_put_nd_path: 6646d7b5aaeSAl Viro path_put(&nd->path); 6656d7b5aaeSAl Viro out_put_link: 6666d7b5aaeSAl Viro path_put(link); 6671da177e4SLinus Torvalds return error; 6681da177e4SLinus Torvalds } 6691da177e4SLinus Torvalds 67031e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 67131e6b01fSNick Piggin { 6720714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 6730714a533SAl Viro struct mount *parent; 67431e6b01fSNick Piggin struct dentry *mountpoint; 67531e6b01fSNick Piggin 6760714a533SAl Viro parent = mnt->mnt_parent; 6770714a533SAl Viro if (&parent->mnt == path->mnt) 67831e6b01fSNick Piggin return 0; 679a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 68031e6b01fSNick Piggin path->dentry = mountpoint; 6810714a533SAl Viro path->mnt = &parent->mnt; 68231e6b01fSNick Piggin return 1; 68331e6b01fSNick Piggin } 68431e6b01fSNick Piggin 685bab77ebfSAl Viro int follow_up(struct path *path) 6861da177e4SLinus Torvalds { 6870714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 6880714a533SAl Viro struct mount *parent; 6891da177e4SLinus Torvalds struct dentry *mountpoint; 69099b7db7bSNick Piggin 691962830dfSAndi Kleen br_read_lock(&vfsmount_lock); 6920714a533SAl Viro parent = mnt->mnt_parent; 6930714a533SAl Viro if (&parent->mnt == path->mnt) { 694962830dfSAndi Kleen br_read_unlock(&vfsmount_lock); 6951da177e4SLinus Torvalds return 0; 6961da177e4SLinus Torvalds } 6970714a533SAl Viro mntget(&parent->mnt); 698a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 699962830dfSAndi Kleen br_read_unlock(&vfsmount_lock); 700bab77ebfSAl Viro dput(path->dentry); 701bab77ebfSAl Viro path->dentry = mountpoint; 702bab77ebfSAl Viro mntput(path->mnt); 7030714a533SAl Viro path->mnt = &parent->mnt; 7041da177e4SLinus Torvalds return 1; 7051da177e4SLinus Torvalds } 7061da177e4SLinus Torvalds 707b5c84bf6SNick Piggin /* 7089875cf80SDavid Howells * Perform an automount 7099875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 7109875cf80SDavid Howells * were called with. 7111da177e4SLinus Torvalds */ 7129875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 7139875cf80SDavid Howells bool *need_mntput) 71431e6b01fSNick Piggin { 7159875cf80SDavid Howells struct vfsmount *mnt; 716ea5b778aSDavid Howells int err; 7179875cf80SDavid Howells 7189875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 7199875cf80SDavid Howells return -EREMOTE; 7209875cf80SDavid Howells 7210ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 7220ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 7230ec26fd0SMiklos Szeredi * the name. 7240ec26fd0SMiklos Szeredi * 7250ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 7265a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 7270ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 7280ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 7290ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 7300ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 7315a30d8a2SDavid Howells */ 7325a30d8a2SDavid Howells if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 733d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 7345a30d8a2SDavid Howells path->dentry->d_inode) 7359875cf80SDavid Howells return -EISDIR; 7360ec26fd0SMiklos Szeredi 7379875cf80SDavid Howells current->total_link_count++; 7389875cf80SDavid Howells if (current->total_link_count >= 40) 7399875cf80SDavid Howells return -ELOOP; 7409875cf80SDavid Howells 7419875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 7429875cf80SDavid Howells if (IS_ERR(mnt)) { 7439875cf80SDavid Howells /* 7449875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 7459875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 7469875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 7479875cf80SDavid Howells * 7489875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 7499875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 7509875cf80SDavid Howells * the path is inaccessible and we should say so. 7519875cf80SDavid Howells */ 75249084c3bSAl Viro if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) 7539875cf80SDavid Howells return -EREMOTE; 7549875cf80SDavid Howells return PTR_ERR(mnt); 75531e6b01fSNick Piggin } 756ea5b778aSDavid Howells 7579875cf80SDavid Howells if (!mnt) /* mount collision */ 7589875cf80SDavid Howells return 0; 7599875cf80SDavid Howells 7608aef1884SAl Viro if (!*need_mntput) { 7618aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 7628aef1884SAl Viro mntget(path->mnt); 7638aef1884SAl Viro *need_mntput = true; 7648aef1884SAl Viro } 76519a167afSAl Viro err = finish_automount(mnt, path); 766ea5b778aSDavid Howells 767ea5b778aSDavid Howells switch (err) { 768ea5b778aSDavid Howells case -EBUSY: 769ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 77019a167afSAl Viro return 0; 771ea5b778aSDavid Howells case 0: 7728aef1884SAl Viro path_put(path); 7739875cf80SDavid Howells path->mnt = mnt; 7749875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 7759875cf80SDavid Howells return 0; 77619a167afSAl Viro default: 77719a167afSAl Viro return err; 7789875cf80SDavid Howells } 77919a167afSAl Viro 780ea5b778aSDavid Howells } 7819875cf80SDavid Howells 7829875cf80SDavid Howells /* 7839875cf80SDavid Howells * Handle a dentry that is managed in some way. 784cc53ce53SDavid Howells * - Flagged for transit management (autofs) 7859875cf80SDavid Howells * - Flagged as mountpoint 7869875cf80SDavid Howells * - Flagged as automount point 7879875cf80SDavid Howells * 7889875cf80SDavid Howells * This may only be called in refwalk mode. 7899875cf80SDavid Howells * 7909875cf80SDavid Howells * Serialization is taken care of in namespace.c 7919875cf80SDavid Howells */ 7929875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 7939875cf80SDavid Howells { 7948aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 7959875cf80SDavid Howells unsigned managed; 7969875cf80SDavid Howells bool need_mntput = false; 7978aef1884SAl Viro int ret = 0; 7989875cf80SDavid Howells 7999875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 8009875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 8019875cf80SDavid Howells * the components of that value change under us */ 8029875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 8039875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 8049875cf80SDavid Howells unlikely(managed != 0)) { 805cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 806cc53ce53SDavid Howells * being held. */ 807cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 808cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 809cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 8101aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 811cc53ce53SDavid Howells if (ret < 0) 8128aef1884SAl Viro break; 813cc53ce53SDavid Howells } 814cc53ce53SDavid Howells 8159875cf80SDavid Howells /* Transit to a mounted filesystem. */ 8169875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 8179875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 8189875cf80SDavid Howells if (mounted) { 8199875cf80SDavid Howells dput(path->dentry); 8209875cf80SDavid Howells if (need_mntput) 821463ffb2eSAl Viro mntput(path->mnt); 822463ffb2eSAl Viro path->mnt = mounted; 823463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 8249875cf80SDavid Howells need_mntput = true; 8259875cf80SDavid Howells continue; 826463ffb2eSAl Viro } 827463ffb2eSAl Viro 8289875cf80SDavid Howells /* Something is mounted on this dentry in another 8299875cf80SDavid Howells * namespace and/or whatever was mounted there in this 8309875cf80SDavid Howells * namespace got unmounted before we managed to get the 8319875cf80SDavid Howells * vfsmount_lock */ 8321da177e4SLinus Torvalds } 8339875cf80SDavid Howells 8349875cf80SDavid Howells /* Handle an automount point */ 8359875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 8369875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 8379875cf80SDavid Howells if (ret < 0) 8388aef1884SAl Viro break; 8399875cf80SDavid Howells continue; 8409875cf80SDavid Howells } 8419875cf80SDavid Howells 8429875cf80SDavid Howells /* We didn't change the current path point */ 8439875cf80SDavid Howells break; 8449875cf80SDavid Howells } 8458aef1884SAl Viro 8468aef1884SAl Viro if (need_mntput && path->mnt == mnt) 8478aef1884SAl Viro mntput(path->mnt); 8488aef1884SAl Viro if (ret == -EISDIR) 8498aef1884SAl Viro ret = 0; 850a3fbbde7SAl Viro return ret < 0 ? ret : need_mntput; 8511da177e4SLinus Torvalds } 8521da177e4SLinus Torvalds 853cc53ce53SDavid Howells int follow_down_one(struct path *path) 8541da177e4SLinus Torvalds { 8551da177e4SLinus Torvalds struct vfsmount *mounted; 8561da177e4SLinus Torvalds 8571c755af4SAl Viro mounted = lookup_mnt(path); 8581da177e4SLinus Torvalds if (mounted) { 8599393bd07SAl Viro dput(path->dentry); 8609393bd07SAl Viro mntput(path->mnt); 8619393bd07SAl Viro path->mnt = mounted; 8629393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 8631da177e4SLinus Torvalds return 1; 8641da177e4SLinus Torvalds } 8651da177e4SLinus Torvalds return 0; 8661da177e4SLinus Torvalds } 8671da177e4SLinus Torvalds 86862a7375eSIan Kent static inline bool managed_dentry_might_block(struct dentry *dentry) 86962a7375eSIan Kent { 87062a7375eSIan Kent return (dentry->d_flags & DCACHE_MANAGE_TRANSIT && 87162a7375eSIan Kent dentry->d_op->d_manage(dentry, true) < 0); 87262a7375eSIan Kent } 87362a7375eSIan Kent 8749875cf80SDavid Howells /* 875287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 876287548e4SAl Viro * we meet a managed dentry that would need blocking. 8779875cf80SDavid Howells */ 8789875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 879287548e4SAl Viro struct inode **inode) 8809875cf80SDavid Howells { 88162a7375eSIan Kent for (;;) { 882c7105365SAl Viro struct mount *mounted; 88362a7375eSIan Kent /* 88462a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 88562a7375eSIan Kent * that wants to block transit. 88662a7375eSIan Kent */ 887287548e4SAl Viro if (unlikely(managed_dentry_might_block(path->dentry))) 888ab90911fSDavid Howells return false; 88962a7375eSIan Kent 89062a7375eSIan Kent if (!d_mountpoint(path->dentry)) 89162a7375eSIan Kent break; 89262a7375eSIan Kent 8939875cf80SDavid Howells mounted = __lookup_mnt(path->mnt, path->dentry, 1); 8949875cf80SDavid Howells if (!mounted) 8959875cf80SDavid Howells break; 896c7105365SAl Viro path->mnt = &mounted->mnt; 897c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 898a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 8999875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 90059430262SLinus Torvalds /* 90159430262SLinus Torvalds * Update the inode too. We don't need to re-check the 90259430262SLinus Torvalds * dentry sequence number here after this d_inode read, 90359430262SLinus Torvalds * because a mount-point is always pinned. 90459430262SLinus Torvalds */ 90559430262SLinus Torvalds *inode = path->dentry->d_inode; 9069875cf80SDavid Howells } 9079875cf80SDavid Howells return true; 9089875cf80SDavid Howells } 9099875cf80SDavid Howells 910dea39376SAl Viro static void follow_mount_rcu(struct nameidata *nd) 911287548e4SAl Viro { 912dea39376SAl Viro while (d_mountpoint(nd->path.dentry)) { 913c7105365SAl Viro struct mount *mounted; 914dea39376SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1); 915287548e4SAl Viro if (!mounted) 916287548e4SAl Viro break; 917c7105365SAl Viro nd->path.mnt = &mounted->mnt; 918c7105365SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 919dea39376SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 920287548e4SAl Viro } 921287548e4SAl Viro } 922287548e4SAl Viro 92331e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 92431e6b01fSNick Piggin { 92531e6b01fSNick Piggin set_root_rcu(nd); 92631e6b01fSNick Piggin 92731e6b01fSNick Piggin while (1) { 92831e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 92931e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 93031e6b01fSNick Piggin break; 93131e6b01fSNick Piggin } 93231e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 93331e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 93431e6b01fSNick Piggin struct dentry *parent = old->d_parent; 93531e6b01fSNick Piggin unsigned seq; 93631e6b01fSNick Piggin 93731e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 93831e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 939ef7562d5SAl Viro goto failed; 94031e6b01fSNick Piggin nd->path.dentry = parent; 94131e6b01fSNick Piggin nd->seq = seq; 94231e6b01fSNick Piggin break; 94331e6b01fSNick Piggin } 94431e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 94531e6b01fSNick Piggin break; 94631e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 94731e6b01fSNick Piggin } 948dea39376SAl Viro follow_mount_rcu(nd); 949dea39376SAl Viro nd->inode = nd->path.dentry->d_inode; 95031e6b01fSNick Piggin return 0; 951ef7562d5SAl Viro 952ef7562d5SAl Viro failed: 953ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 9545b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 955ef7562d5SAl Viro nd->root.mnt = NULL; 956ef7562d5SAl Viro rcu_read_unlock(); 957962830dfSAndi Kleen br_read_unlock(&vfsmount_lock); 958ef7562d5SAl Viro return -ECHILD; 95931e6b01fSNick Piggin } 96031e6b01fSNick Piggin 9619875cf80SDavid Howells /* 962cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 963cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 964cc53ce53SDavid Howells * caller is permitted to proceed or not. 965cc53ce53SDavid Howells */ 9667cc90cc3SAl Viro int follow_down(struct path *path) 967cc53ce53SDavid Howells { 968cc53ce53SDavid Howells unsigned managed; 969cc53ce53SDavid Howells int ret; 970cc53ce53SDavid Howells 971cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 972cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 973cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 974cc53ce53SDavid Howells * being held. 975cc53ce53SDavid Howells * 976cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 977cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 978cc53ce53SDavid Howells * other than its daemon the right to mount on its 979cc53ce53SDavid Howells * superstructure. 980cc53ce53SDavid Howells * 981cc53ce53SDavid Howells * The filesystem may sleep at this point. 982cc53ce53SDavid Howells */ 983cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 984cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 985cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 986ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 9871aed3e42SAl Viro path->dentry, false); 988cc53ce53SDavid Howells if (ret < 0) 989cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 990cc53ce53SDavid Howells } 991cc53ce53SDavid Howells 992cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 993cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 994cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 995cc53ce53SDavid Howells if (!mounted) 996cc53ce53SDavid Howells break; 997cc53ce53SDavid Howells dput(path->dentry); 998cc53ce53SDavid Howells mntput(path->mnt); 999cc53ce53SDavid Howells path->mnt = mounted; 1000cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1001cc53ce53SDavid Howells continue; 1002cc53ce53SDavid Howells } 1003cc53ce53SDavid Howells 1004cc53ce53SDavid Howells /* Don't handle automount points here */ 1005cc53ce53SDavid Howells break; 1006cc53ce53SDavid Howells } 1007cc53ce53SDavid Howells return 0; 1008cc53ce53SDavid Howells } 1009cc53ce53SDavid Howells 1010cc53ce53SDavid Howells /* 10119875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 10129875cf80SDavid Howells */ 10139875cf80SDavid Howells static void follow_mount(struct path *path) 10149875cf80SDavid Howells { 10159875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 10169875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10179875cf80SDavid Howells if (!mounted) 10189875cf80SDavid Howells break; 10199875cf80SDavid Howells dput(path->dentry); 10209875cf80SDavid Howells mntput(path->mnt); 10219875cf80SDavid Howells path->mnt = mounted; 10229875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 10239875cf80SDavid Howells } 10249875cf80SDavid Howells } 10259875cf80SDavid Howells 102631e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 10271da177e4SLinus Torvalds { 10282a737871SAl Viro set_root(nd); 1029e518ddb7SAndreas Mohr 10301da177e4SLinus Torvalds while(1) { 10314ac91378SJan Blunck struct dentry *old = nd->path.dentry; 10321da177e4SLinus Torvalds 10332a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 10342a737871SAl Viro nd->path.mnt == nd->root.mnt) { 10351da177e4SLinus Torvalds break; 10361da177e4SLinus Torvalds } 10374ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 10383088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 10393088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 10401da177e4SLinus Torvalds dput(old); 10411da177e4SLinus Torvalds break; 10421da177e4SLinus Torvalds } 10433088dd70SAl Viro if (!follow_up(&nd->path)) 10441da177e4SLinus Torvalds break; 10451da177e4SLinus Torvalds } 104679ed0226SAl Viro follow_mount(&nd->path); 104731e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 10481da177e4SLinus Torvalds } 10491da177e4SLinus Torvalds 10501da177e4SLinus Torvalds /* 1051bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1052bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1053bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1054bad61189SMiklos Szeredi * 1055bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1056baa03890SNick Piggin */ 1057bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1058bad61189SMiklos Szeredi struct nameidata *nd, bool *need_lookup) 1059baa03890SNick Piggin { 1060baa03890SNick Piggin struct dentry *dentry; 1061bad61189SMiklos Szeredi int error; 1062baa03890SNick Piggin 1063bad61189SMiklos Szeredi *need_lookup = false; 1064bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1065bad61189SMiklos Szeredi if (dentry) { 1066bad61189SMiklos Szeredi if (d_need_lookup(dentry)) { 1067bad61189SMiklos Szeredi *need_lookup = true; 1068bad61189SMiklos Szeredi } else if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1069bad61189SMiklos Szeredi error = d_revalidate(dentry, nd); 1070bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1071bad61189SMiklos Szeredi if (error < 0) { 1072bad61189SMiklos Szeredi dput(dentry); 1073bad61189SMiklos Szeredi return ERR_PTR(error); 1074bad61189SMiklos Szeredi } else if (!d_invalidate(dentry)) { 1075bad61189SMiklos Szeredi dput(dentry); 1076bad61189SMiklos Szeredi dentry = NULL; 1077bad61189SMiklos Szeredi } 1078bad61189SMiklos Szeredi } 1079bad61189SMiklos Szeredi } 1080bad61189SMiklos Szeredi } 1081baa03890SNick Piggin 1082bad61189SMiklos Szeredi if (!dentry) { 1083bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1084baa03890SNick Piggin if (unlikely(!dentry)) 1085baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1086baa03890SNick Piggin 1087bad61189SMiklos Szeredi *need_lookup = true; 1088baa03890SNick Piggin } 1089baa03890SNick Piggin return dentry; 1090baa03890SNick Piggin } 1091baa03890SNick Piggin 1092baa03890SNick Piggin /* 1093bad61189SMiklos Szeredi * Call i_op->lookup on the dentry. The dentry must be negative but may be 1094bad61189SMiklos Szeredi * hashed if it was pouplated with DCACHE_NEED_LOOKUP. 1095bad61189SMiklos Szeredi * 1096bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 109744396f4bSJosef Bacik */ 1098bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 109944396f4bSJosef Bacik struct nameidata *nd) 110044396f4bSJosef Bacik { 110144396f4bSJosef Bacik struct dentry *old; 110244396f4bSJosef Bacik 110344396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1104bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1105e188dc02SMiklos Szeredi dput(dentry); 110644396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1107e188dc02SMiklos Szeredi } 110844396f4bSJosef Bacik 1109bad61189SMiklos Szeredi old = dir->i_op->lookup(dir, dentry, nd); 111044396f4bSJosef Bacik if (unlikely(old)) { 111144396f4bSJosef Bacik dput(dentry); 111244396f4bSJosef Bacik dentry = old; 111344396f4bSJosef Bacik } 111444396f4bSJosef Bacik return dentry; 111544396f4bSJosef Bacik } 111644396f4bSJosef Bacik 1117a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 1118a3255546SAl Viro struct dentry *base, struct nameidata *nd) 1119a3255546SAl Viro { 1120bad61189SMiklos Szeredi bool need_lookup; 1121a3255546SAl Viro struct dentry *dentry; 1122a3255546SAl Viro 1123bad61189SMiklos Szeredi dentry = lookup_dcache(name, base, nd, &need_lookup); 1124bad61189SMiklos Szeredi if (!need_lookup) 1125a3255546SAl Viro return dentry; 1126bad61189SMiklos Szeredi 1127bad61189SMiklos Szeredi return lookup_real(base->d_inode, dentry, nd); 1128a3255546SAl Viro } 1129a3255546SAl Viro 113044396f4bSJosef Bacik /* 11311da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 11321da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 11331da177e4SLinus Torvalds * It _is_ time-critical. 11341da177e4SLinus Torvalds */ 1135697f514dSMiklos Szeredi static int lookup_fast(struct nameidata *nd, struct qstr *name, 113631e6b01fSNick Piggin struct path *path, struct inode **inode) 11371da177e4SLinus Torvalds { 11384ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 113931e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 11405a18fff2SAl Viro int need_reval = 1; 11415a18fff2SAl Viro int status = 1; 11429875cf80SDavid Howells int err; 11439875cf80SDavid Howells 11443cac260aSAl Viro /* 1145b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1146b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1147b04f784eSNick Piggin * do the non-racy lookup, below. 1148b04f784eSNick Piggin */ 114931e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 115031e6b01fSNick Piggin unsigned seq; 115112f8ad4bSLinus Torvalds dentry = __d_lookup_rcu(parent, name, &seq, nd->inode); 11525a18fff2SAl Viro if (!dentry) 11535a18fff2SAl Viro goto unlazy; 11545a18fff2SAl Viro 115512f8ad4bSLinus Torvalds /* 115612f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 115712f8ad4bSLinus Torvalds * the dentry name information from lookup. 115812f8ad4bSLinus Torvalds */ 115912f8ad4bSLinus Torvalds *inode = dentry->d_inode; 116012f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 116112f8ad4bSLinus Torvalds return -ECHILD; 116212f8ad4bSLinus Torvalds 116312f8ad4bSLinus Torvalds /* 116412f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 116512f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 116612f8ad4bSLinus Torvalds * 116712f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 116812f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 116912f8ad4bSLinus Torvalds */ 117031e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 117131e6b01fSNick Piggin return -ECHILD; 117231e6b01fSNick Piggin nd->seq = seq; 11735a18fff2SAl Viro 1174fa4ee159SMiklos Szeredi if (unlikely(d_need_lookup(dentry))) 1175fa4ee159SMiklos Szeredi goto unlazy; 117624643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 11775a18fff2SAl Viro status = d_revalidate(dentry, nd); 11785a18fff2SAl Viro if (unlikely(status <= 0)) { 11795a18fff2SAl Viro if (status != -ECHILD) 11805a18fff2SAl Viro need_reval = 0; 11815a18fff2SAl Viro goto unlazy; 11825a18fff2SAl Viro } 118324643087SAl Viro } 118431e6b01fSNick Piggin path->mnt = mnt; 118531e6b01fSNick Piggin path->dentry = dentry; 1186d6e9bd25SAl Viro if (unlikely(!__follow_mount_rcu(nd, path, inode))) 1187d6e9bd25SAl Viro goto unlazy; 1188d6e9bd25SAl Viro if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) 1189d6e9bd25SAl Viro goto unlazy; 11909875cf80SDavid Howells return 0; 11915a18fff2SAl Viro unlazy: 119219660af7SAl Viro if (unlazy_walk(nd, dentry)) 11935a18fff2SAl Viro return -ECHILD; 11945a18fff2SAl Viro } else { 119531e6b01fSNick Piggin dentry = __d_lookup(parent, name); 119624643087SAl Viro } 11975a18fff2SAl Viro 119881e6f520SAl Viro if (unlikely(!dentry)) 119981e6f520SAl Viro goto need_lookup; 12005a18fff2SAl Viro 120181e6f520SAl Viro if (unlikely(d_need_lookup(dentry))) { 120281e6f520SAl Viro dput(dentry); 120381e6f520SAl Viro goto need_lookup; 12045a18fff2SAl Viro } 120581e6f520SAl Viro 12065a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 12075a18fff2SAl Viro status = d_revalidate(dentry, nd); 12085a18fff2SAl Viro if (unlikely(status <= 0)) { 12095a18fff2SAl Viro if (status < 0) { 12105a18fff2SAl Viro dput(dentry); 12115a18fff2SAl Viro return status; 12125a18fff2SAl Viro } 12135a18fff2SAl Viro if (!d_invalidate(dentry)) { 12145a18fff2SAl Viro dput(dentry); 121581e6f520SAl Viro goto need_lookup; 12165a18fff2SAl Viro } 12175a18fff2SAl Viro } 1218697f514dSMiklos Szeredi 12191da177e4SLinus Torvalds path->mnt = mnt; 12201da177e4SLinus Torvalds path->dentry = dentry; 12219875cf80SDavid Howells err = follow_managed(path, nd->flags); 122289312214SIan Kent if (unlikely(err < 0)) { 122389312214SIan Kent path_put_conditional(path, nd); 12249875cf80SDavid Howells return err; 122589312214SIan Kent } 1226a3fbbde7SAl Viro if (err) 1227a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 122831e6b01fSNick Piggin *inode = path->dentry->d_inode; 12291da177e4SLinus Torvalds return 0; 123081e6f520SAl Viro 123181e6f520SAl Viro need_lookup: 1232697f514dSMiklos Szeredi return 1; 1233697f514dSMiklos Szeredi } 1234697f514dSMiklos Szeredi 1235697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1236697f514dSMiklos Szeredi static int lookup_slow(struct nameidata *nd, struct qstr *name, 1237697f514dSMiklos Szeredi struct path *path) 1238697f514dSMiklos Szeredi { 1239697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1240697f514dSMiklos Szeredi int err; 1241697f514dSMiklos Szeredi 1242697f514dSMiklos Szeredi parent = nd->path.dentry; 124381e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 124481e6f520SAl Viro 124581e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 124681e6f520SAl Viro dentry = __lookup_hash(name, parent, nd); 124781e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 124881e6f520SAl Viro if (IS_ERR(dentry)) 124981e6f520SAl Viro return PTR_ERR(dentry); 1250697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1251697f514dSMiklos Szeredi path->dentry = dentry; 1252697f514dSMiklos Szeredi err = follow_managed(path, nd->flags); 1253697f514dSMiklos Szeredi if (unlikely(err < 0)) { 1254697f514dSMiklos Szeredi path_put_conditional(path, nd); 1255697f514dSMiklos Szeredi return err; 1256697f514dSMiklos Szeredi } 1257697f514dSMiklos Szeredi if (err) 1258697f514dSMiklos Szeredi nd->flags |= LOOKUP_JUMPED; 1259697f514dSMiklos Szeredi return 0; 12601da177e4SLinus Torvalds } 12611da177e4SLinus Torvalds 126252094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 126352094c8aSAl Viro { 126452094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 12654ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 126652094c8aSAl Viro if (err != -ECHILD) 126752094c8aSAl Viro return err; 126819660af7SAl Viro if (unlazy_walk(nd, NULL)) 126952094c8aSAl Viro return -ECHILD; 127052094c8aSAl Viro } 12714ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 127252094c8aSAl Viro } 127352094c8aSAl Viro 12749856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 12759856fa1bSAl Viro { 12769856fa1bSAl Viro if (type == LAST_DOTDOT) { 12779856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 12789856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 12799856fa1bSAl Viro return -ECHILD; 12809856fa1bSAl Viro } else 12819856fa1bSAl Viro follow_dotdot(nd); 12829856fa1bSAl Viro } 12839856fa1bSAl Viro return 0; 12849856fa1bSAl Viro } 12859856fa1bSAl Viro 1286951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1287951361f9SAl Viro { 1288951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1289951361f9SAl Viro path_put(&nd->path); 1290951361f9SAl Viro } else { 1291951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 12925b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1293951361f9SAl Viro nd->root.mnt = NULL; 1294951361f9SAl Viro rcu_read_unlock(); 1295962830dfSAndi Kleen br_read_unlock(&vfsmount_lock); 1296951361f9SAl Viro } 1297951361f9SAl Viro } 1298951361f9SAl Viro 12993ddcd056SLinus Torvalds /* 13003ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 13013ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 13023ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 13033ddcd056SLinus Torvalds * for the common case. 13043ddcd056SLinus Torvalds */ 13057813b94aSLinus Torvalds static inline int should_follow_link(struct inode *inode, int follow) 13063ddcd056SLinus Torvalds { 13073ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) { 13083ddcd056SLinus Torvalds if (likely(inode->i_op->follow_link)) 13093ddcd056SLinus Torvalds return follow; 13103ddcd056SLinus Torvalds 13113ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 13123ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 13133ddcd056SLinus Torvalds inode->i_opflags |= IOP_NOFOLLOW; 13143ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 13153ddcd056SLinus Torvalds } 13163ddcd056SLinus Torvalds return 0; 13173ddcd056SLinus Torvalds } 13183ddcd056SLinus Torvalds 1319ce57dfc1SAl Viro static inline int walk_component(struct nameidata *nd, struct path *path, 1320ce57dfc1SAl Viro struct qstr *name, int type, int follow) 1321ce57dfc1SAl Viro { 1322ce57dfc1SAl Viro struct inode *inode; 1323ce57dfc1SAl Viro int err; 1324ce57dfc1SAl Viro /* 1325ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1326ce57dfc1SAl Viro * to be able to know about the current root directory and 1327ce57dfc1SAl Viro * parent relationships. 1328ce57dfc1SAl Viro */ 1329ce57dfc1SAl Viro if (unlikely(type != LAST_NORM)) 1330ce57dfc1SAl Viro return handle_dots(nd, type); 1331697f514dSMiklos Szeredi err = lookup_fast(nd, name, path, &inode); 1332ce57dfc1SAl Viro if (unlikely(err)) { 1333697f514dSMiklos Szeredi if (err < 0) 1334697f514dSMiklos Szeredi goto out_err; 1335697f514dSMiklos Szeredi 1336697f514dSMiklos Szeredi err = lookup_slow(nd, name, path); 1337697f514dSMiklos Szeredi if (err < 0) 1338697f514dSMiklos Szeredi goto out_err; 1339697f514dSMiklos Szeredi 1340697f514dSMiklos Szeredi inode = path->dentry->d_inode; 1341ce57dfc1SAl Viro } 1342697f514dSMiklos Szeredi err = -ENOENT; 1343697f514dSMiklos Szeredi if (!inode) 1344697f514dSMiklos Szeredi goto out_path_put; 1345697f514dSMiklos Szeredi 13467813b94aSLinus Torvalds if (should_follow_link(inode, follow)) { 134719660af7SAl Viro if (nd->flags & LOOKUP_RCU) { 134819660af7SAl Viro if (unlikely(unlazy_walk(nd, path->dentry))) { 1349697f514dSMiklos Szeredi err = -ECHILD; 1350697f514dSMiklos Szeredi goto out_err; 135119660af7SAl Viro } 135219660af7SAl Viro } 1353ce57dfc1SAl Viro BUG_ON(inode != path->dentry->d_inode); 1354ce57dfc1SAl Viro return 1; 1355ce57dfc1SAl Viro } 1356ce57dfc1SAl Viro path_to_nameidata(path, nd); 1357ce57dfc1SAl Viro nd->inode = inode; 1358ce57dfc1SAl Viro return 0; 1359697f514dSMiklos Szeredi 1360697f514dSMiklos Szeredi out_path_put: 1361697f514dSMiklos Szeredi path_to_nameidata(path, nd); 1362697f514dSMiklos Szeredi out_err: 1363697f514dSMiklos Szeredi terminate_walk(nd); 1364697f514dSMiklos Szeredi return err; 1365ce57dfc1SAl Viro } 1366ce57dfc1SAl Viro 13671da177e4SLinus Torvalds /* 1368b356379aSAl Viro * This limits recursive symlink follows to 8, while 1369b356379aSAl Viro * limiting consecutive symlinks to 40. 1370b356379aSAl Viro * 1371b356379aSAl Viro * Without that kind of total limit, nasty chains of consecutive 1372b356379aSAl Viro * symlinks can cause almost arbitrarily long lookups. 1373b356379aSAl Viro */ 1374b356379aSAl Viro static inline int nested_symlink(struct path *path, struct nameidata *nd) 1375b356379aSAl Viro { 1376b356379aSAl Viro int res; 1377b356379aSAl Viro 1378b356379aSAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 1379b356379aSAl Viro path_put_conditional(path, nd); 1380b356379aSAl Viro path_put(&nd->path); 1381b356379aSAl Viro return -ELOOP; 1382b356379aSAl Viro } 13831a4022f8SErez Zadok BUG_ON(nd->depth >= MAX_NESTED_LINKS); 1384b356379aSAl Viro 1385b356379aSAl Viro nd->depth++; 1386b356379aSAl Viro current->link_count++; 1387b356379aSAl Viro 1388b356379aSAl Viro do { 1389b356379aSAl Viro struct path link = *path; 1390b356379aSAl Viro void *cookie; 1391574197e0SAl Viro 1392574197e0SAl Viro res = follow_link(&link, nd, &cookie); 13936d7b5aaeSAl Viro if (res) 13946d7b5aaeSAl Viro break; 1395b356379aSAl Viro res = walk_component(nd, path, &nd->last, 1396b356379aSAl Viro nd->last_type, LOOKUP_FOLLOW); 1397574197e0SAl Viro put_link(nd, &link, cookie); 1398b356379aSAl Viro } while (res > 0); 1399b356379aSAl Viro 1400b356379aSAl Viro current->link_count--; 1401b356379aSAl Viro nd->depth--; 1402b356379aSAl Viro return res; 1403b356379aSAl Viro } 1404b356379aSAl Viro 1405b356379aSAl Viro /* 14063ddcd056SLinus Torvalds * We really don't want to look at inode->i_op->lookup 14073ddcd056SLinus Torvalds * when we don't have to. So we keep a cache bit in 14083ddcd056SLinus Torvalds * the inode ->i_opflags field that says "yes, we can 14093ddcd056SLinus Torvalds * do lookup on this inode". 14103ddcd056SLinus Torvalds */ 14113ddcd056SLinus Torvalds static inline int can_lookup(struct inode *inode) 14123ddcd056SLinus Torvalds { 14133ddcd056SLinus Torvalds if (likely(inode->i_opflags & IOP_LOOKUP)) 14143ddcd056SLinus Torvalds return 1; 14153ddcd056SLinus Torvalds if (likely(!inode->i_op->lookup)) 14163ddcd056SLinus Torvalds return 0; 14173ddcd056SLinus Torvalds 14183ddcd056SLinus Torvalds /* We do this once for the lifetime of the inode */ 14193ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 14203ddcd056SLinus Torvalds inode->i_opflags |= IOP_LOOKUP; 14213ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 14223ddcd056SLinus Torvalds return 1; 14233ddcd056SLinus Torvalds } 14243ddcd056SLinus Torvalds 1425bfcfaa77SLinus Torvalds /* 1426bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1427bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1428bfcfaa77SLinus Torvalds * 1429bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1430bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1431bfcfaa77SLinus Torvalds * fast. 1432bfcfaa77SLinus Torvalds * 1433bfcfaa77SLinus Torvalds * - Little-endian machines (so that we can generate the mask 1434bfcfaa77SLinus Torvalds * of low bytes efficiently). Again, we *could* do a byte 1435bfcfaa77SLinus Torvalds * swapping load on big-endian architectures if that is not 1436bfcfaa77SLinus Torvalds * expensive enough to make the optimization worthless. 1437bfcfaa77SLinus Torvalds * 1438bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1439bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1440bfcfaa77SLinus Torvalds * crossing operation. 1441bfcfaa77SLinus Torvalds * 1442bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1443bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1444bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1445bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1446bfcfaa77SLinus Torvalds */ 1447bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1448bfcfaa77SLinus Torvalds 1449f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1450bfcfaa77SLinus Torvalds 1451f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1452bfcfaa77SLinus Torvalds 1453bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1454bfcfaa77SLinus Torvalds { 1455bfcfaa77SLinus Torvalds hash += hash >> (8*sizeof(int)); 1456bfcfaa77SLinus Torvalds return hash; 1457bfcfaa77SLinus Torvalds } 1458bfcfaa77SLinus Torvalds 1459bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1460bfcfaa77SLinus Torvalds 1461bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1462bfcfaa77SLinus Torvalds 1463bfcfaa77SLinus Torvalds #endif 1464bfcfaa77SLinus Torvalds 1465bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1466bfcfaa77SLinus Torvalds { 1467bfcfaa77SLinus Torvalds unsigned long a, mask; 1468bfcfaa77SLinus Torvalds unsigned long hash = 0; 1469bfcfaa77SLinus Torvalds 1470bfcfaa77SLinus Torvalds for (;;) { 1471e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1472bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1473bfcfaa77SLinus Torvalds break; 1474bfcfaa77SLinus Torvalds hash += a; 1475f132c5beSAl Viro hash *= 9; 1476bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1477bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1478bfcfaa77SLinus Torvalds if (!len) 1479bfcfaa77SLinus Torvalds goto done; 1480bfcfaa77SLinus Torvalds } 1481bfcfaa77SLinus Torvalds mask = ~(~0ul << len*8); 1482bfcfaa77SLinus Torvalds hash += mask & a; 1483bfcfaa77SLinus Torvalds done: 1484bfcfaa77SLinus Torvalds return fold_hash(hash); 1485bfcfaa77SLinus Torvalds } 1486bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1487bfcfaa77SLinus Torvalds 1488bfcfaa77SLinus Torvalds /* 1489bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1490bfcfaa77SLinus Torvalds * return the length of the component; 1491bfcfaa77SLinus Torvalds */ 1492bfcfaa77SLinus Torvalds static inline unsigned long hash_name(const char *name, unsigned int *hashp) 1493bfcfaa77SLinus Torvalds { 149436126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 149536126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1496bfcfaa77SLinus Torvalds 1497bfcfaa77SLinus Torvalds hash = a = 0; 1498bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1499bfcfaa77SLinus Torvalds do { 1500bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1501bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1502e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 150336126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 150436126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1505bfcfaa77SLinus Torvalds 150636126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 150736126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 150836126f8fSLinus Torvalds 150936126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 151036126f8fSLinus Torvalds 151136126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 1512bfcfaa77SLinus Torvalds *hashp = fold_hash(hash); 1513bfcfaa77SLinus Torvalds 151436126f8fSLinus Torvalds return len + find_zero(mask); 1515bfcfaa77SLinus Torvalds } 1516bfcfaa77SLinus Torvalds 1517bfcfaa77SLinus Torvalds #else 1518bfcfaa77SLinus Torvalds 15190145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 15200145acc2SLinus Torvalds { 15210145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 15220145acc2SLinus Torvalds while (len--) 15230145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 15240145acc2SLinus Torvalds return end_name_hash(hash); 15250145acc2SLinus Torvalds } 1526ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 15270145acc2SLinus Torvalds 15283ddcd056SLinus Torvalds /* 1529200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1530200e9ef7SLinus Torvalds * one character. 1531200e9ef7SLinus Torvalds */ 1532200e9ef7SLinus Torvalds static inline unsigned long hash_name(const char *name, unsigned int *hashp) 1533200e9ef7SLinus Torvalds { 1534200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1535200e9ef7SLinus Torvalds unsigned long len = 0, c; 1536200e9ef7SLinus Torvalds 1537200e9ef7SLinus Torvalds c = (unsigned char)*name; 1538200e9ef7SLinus Torvalds do { 1539200e9ef7SLinus Torvalds len++; 1540200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1541200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1542200e9ef7SLinus Torvalds } while (c && c != '/'); 1543200e9ef7SLinus Torvalds *hashp = end_name_hash(hash); 1544200e9ef7SLinus Torvalds return len; 1545200e9ef7SLinus Torvalds } 1546200e9ef7SLinus Torvalds 1547bfcfaa77SLinus Torvalds #endif 1548bfcfaa77SLinus Torvalds 1549200e9ef7SLinus Torvalds /* 15501da177e4SLinus Torvalds * Name resolution. 1551ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1552ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 15531da177e4SLinus Torvalds * 1554ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1555ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 15561da177e4SLinus Torvalds */ 15576de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 15581da177e4SLinus Torvalds { 15591da177e4SLinus Torvalds struct path next; 15601da177e4SLinus Torvalds int err; 15611da177e4SLinus Torvalds 15621da177e4SLinus Torvalds while (*name=='/') 15631da177e4SLinus Torvalds name++; 15641da177e4SLinus Torvalds if (!*name) 1565086e183aSAl Viro return 0; 15661da177e4SLinus Torvalds 15671da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 15681da177e4SLinus Torvalds for(;;) { 15691da177e4SLinus Torvalds struct qstr this; 1570200e9ef7SLinus Torvalds long len; 1571fe479a58SAl Viro int type; 15721da177e4SLinus Torvalds 157352094c8aSAl Viro err = may_lookup(nd); 15741da177e4SLinus Torvalds if (err) 15751da177e4SLinus Torvalds break; 15761da177e4SLinus Torvalds 1577200e9ef7SLinus Torvalds len = hash_name(name, &this.hash); 15781da177e4SLinus Torvalds this.name = name; 1579200e9ef7SLinus Torvalds this.len = len; 15801da177e4SLinus Torvalds 1581fe479a58SAl Viro type = LAST_NORM; 1582200e9ef7SLinus Torvalds if (name[0] == '.') switch (len) { 1583fe479a58SAl Viro case 2: 1584200e9ef7SLinus Torvalds if (name[1] == '.') { 1585fe479a58SAl Viro type = LAST_DOTDOT; 158616c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 158716c2cd71SAl Viro } 1588fe479a58SAl Viro break; 1589fe479a58SAl Viro case 1: 1590fe479a58SAl Viro type = LAST_DOT; 1591fe479a58SAl Viro } 15925a202bcdSAl Viro if (likely(type == LAST_NORM)) { 15935a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 159416c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 15955a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 15965a202bcdSAl Viro err = parent->d_op->d_hash(parent, nd->inode, 15975a202bcdSAl Viro &this); 15985a202bcdSAl Viro if (err < 0) 15995a202bcdSAl Viro break; 16005a202bcdSAl Viro } 16015a202bcdSAl Viro } 1602fe479a58SAl Viro 1603200e9ef7SLinus Torvalds if (!name[len]) 16041da177e4SLinus Torvalds goto last_component; 1605200e9ef7SLinus Torvalds /* 1606200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1607200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1608200e9ef7SLinus Torvalds */ 1609200e9ef7SLinus Torvalds do { 1610200e9ef7SLinus Torvalds len++; 1611200e9ef7SLinus Torvalds } while (unlikely(name[len] == '/')); 1612200e9ef7SLinus Torvalds if (!name[len]) 1613b356379aSAl Viro goto last_component; 1614200e9ef7SLinus Torvalds name += len; 16151da177e4SLinus Torvalds 1616ce57dfc1SAl Viro err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW); 1617ce57dfc1SAl Viro if (err < 0) 1618ce57dfc1SAl Viro return err; 1619fe479a58SAl Viro 1620ce57dfc1SAl Viro if (err) { 1621b356379aSAl Viro err = nested_symlink(&next, nd); 16221da177e4SLinus Torvalds if (err) 1623a7472babSAl Viro return err; 162431e6b01fSNick Piggin } 16253ddcd056SLinus Torvalds if (can_lookup(nd->inode)) 16261da177e4SLinus Torvalds continue; 16273ddcd056SLinus Torvalds err = -ENOTDIR; 16283ddcd056SLinus Torvalds break; 16291da177e4SLinus Torvalds /* here ends the main loop */ 16301da177e4SLinus Torvalds 16311da177e4SLinus Torvalds last_component: 1632ce57dfc1SAl Viro nd->last = this; 1633ce57dfc1SAl Viro nd->last_type = type; 1634ce57dfc1SAl Viro return 0; 1635ce57dfc1SAl Viro } 1636951361f9SAl Viro terminate_walk(nd); 16371da177e4SLinus Torvalds return err; 16381da177e4SLinus Torvalds } 16391da177e4SLinus Torvalds 164070e9b357SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, 164170e9b357SAl Viro struct nameidata *nd, struct file **fp) 164231e6b01fSNick Piggin { 164331e6b01fSNick Piggin int retval = 0; 164431e6b01fSNick Piggin int fput_needed; 164531e6b01fSNick Piggin struct file *file; 164631e6b01fSNick Piggin 164731e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 164816c2cd71SAl Viro nd->flags = flags | LOOKUP_JUMPED; 164931e6b01fSNick Piggin nd->depth = 0; 16505b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 16515b6ca027SAl Viro struct inode *inode = nd->root.dentry->d_inode; 165273d049a4SAl Viro if (*name) { 16535b6ca027SAl Viro if (!inode->i_op->lookup) 16545b6ca027SAl Viro return -ENOTDIR; 16555b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 16565b6ca027SAl Viro if (retval) 16575b6ca027SAl Viro return retval; 165873d049a4SAl Viro } 16595b6ca027SAl Viro nd->path = nd->root; 16605b6ca027SAl Viro nd->inode = inode; 16615b6ca027SAl Viro if (flags & LOOKUP_RCU) { 1662962830dfSAndi Kleen br_read_lock(&vfsmount_lock); 16635b6ca027SAl Viro rcu_read_lock(); 16645b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 16655b6ca027SAl Viro } else { 16665b6ca027SAl Viro path_get(&nd->path); 16675b6ca027SAl Viro } 16685b6ca027SAl Viro return 0; 16695b6ca027SAl Viro } 16705b6ca027SAl Viro 167131e6b01fSNick Piggin nd->root.mnt = NULL; 167231e6b01fSNick Piggin 167331e6b01fSNick Piggin if (*name=='/') { 1674e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 1675962830dfSAndi Kleen br_read_lock(&vfsmount_lock); 167631e6b01fSNick Piggin rcu_read_lock(); 1677e41f7d4eSAl Viro set_root_rcu(nd); 1678e41f7d4eSAl Viro } else { 1679e41f7d4eSAl Viro set_root(nd); 1680e41f7d4eSAl Viro path_get(&nd->root); 1681e41f7d4eSAl Viro } 168231e6b01fSNick Piggin nd->path = nd->root; 168331e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1684e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 168531e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1686c28cc364SNick Piggin unsigned seq; 168731e6b01fSNick Piggin 1688962830dfSAndi Kleen br_read_lock(&vfsmount_lock); 168931e6b01fSNick Piggin rcu_read_lock(); 169031e6b01fSNick Piggin 1691c28cc364SNick Piggin do { 1692c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 169331e6b01fSNick Piggin nd->path = fs->pwd; 1694c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1695c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1696e41f7d4eSAl Viro } else { 1697e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1698e41f7d4eSAl Viro } 169931e6b01fSNick Piggin } else { 170031e6b01fSNick Piggin struct dentry *dentry; 170131e6b01fSNick Piggin 17021abf0c71SAl Viro file = fget_raw_light(dfd, &fput_needed); 170331e6b01fSNick Piggin retval = -EBADF; 170431e6b01fSNick Piggin if (!file) 170531e6b01fSNick Piggin goto out_fail; 170631e6b01fSNick Piggin 170731e6b01fSNick Piggin dentry = file->f_path.dentry; 170831e6b01fSNick Piggin 1709f52e0c11SAl Viro if (*name) { 171031e6b01fSNick Piggin retval = -ENOTDIR; 171131e6b01fSNick Piggin if (!S_ISDIR(dentry->d_inode->i_mode)) 171231e6b01fSNick Piggin goto fput_fail; 171331e6b01fSNick Piggin 17144ad5abb3SAl Viro retval = inode_permission(dentry->d_inode, MAY_EXEC); 171531e6b01fSNick Piggin if (retval) 171631e6b01fSNick Piggin goto fput_fail; 1717f52e0c11SAl Viro } 171831e6b01fSNick Piggin 171931e6b01fSNick Piggin nd->path = file->f_path; 1720e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 172131e6b01fSNick Piggin if (fput_needed) 172270e9b357SAl Viro *fp = file; 1723c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1724962830dfSAndi Kleen br_read_lock(&vfsmount_lock); 172531e6b01fSNick Piggin rcu_read_lock(); 17265590ff0dSUlrich Drepper } else { 17275dd784d0SJan Blunck path_get(&file->f_path); 17285590ff0dSUlrich Drepper fput_light(file, fput_needed); 17291da177e4SLinus Torvalds } 1730e41f7d4eSAl Viro } 1731e41f7d4eSAl Viro 173231e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 17339b4a9b14SAl Viro return 0; 17342dfdd266SJosef 'Jeff' Sipek 17359b4a9b14SAl Viro fput_fail: 17369b4a9b14SAl Viro fput_light(file, fput_needed); 17379b4a9b14SAl Viro out_fail: 17389b4a9b14SAl Viro return retval; 17399b4a9b14SAl Viro } 17409b4a9b14SAl Viro 1741bd92d7feSAl Viro static inline int lookup_last(struct nameidata *nd, struct path *path) 1742bd92d7feSAl Viro { 1743bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1744bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1745bd92d7feSAl Viro 1746bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 1747bd92d7feSAl Viro return walk_component(nd, path, &nd->last, nd->last_type, 1748bd92d7feSAl Viro nd->flags & LOOKUP_FOLLOW); 1749bd92d7feSAl Viro } 1750bd92d7feSAl Viro 17519b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1752ee0827cdSAl Viro static int path_lookupat(int dfd, const char *name, 17539b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 17549b4a9b14SAl Viro { 175570e9b357SAl Viro struct file *base = NULL; 1756bd92d7feSAl Viro struct path path; 1757bd92d7feSAl Viro int err; 175831e6b01fSNick Piggin 175931e6b01fSNick Piggin /* 176031e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 176131e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 176231e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 176331e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 176431e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 176531e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 176631e6b01fSNick Piggin * analogue, foo_rcu(). 176731e6b01fSNick Piggin * 176831e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 176931e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 177031e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 177131e6b01fSNick Piggin * be able to complete). 177231e6b01fSNick Piggin */ 1773bd92d7feSAl Viro err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); 1774ee0827cdSAl Viro 1775bd92d7feSAl Viro if (unlikely(err)) 1776bd92d7feSAl Viro return err; 1777ee0827cdSAl Viro 1778ee0827cdSAl Viro current->total_link_count = 0; 1779bd92d7feSAl Viro err = link_path_walk(name, nd); 1780bd92d7feSAl Viro 1781bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 1782bd92d7feSAl Viro err = lookup_last(nd, &path); 1783bd92d7feSAl Viro while (err > 0) { 1784bd92d7feSAl Viro void *cookie; 1785bd92d7feSAl Viro struct path link = path; 1786bd92d7feSAl Viro nd->flags |= LOOKUP_PARENT; 1787574197e0SAl Viro err = follow_link(&link, nd, &cookie); 17886d7b5aaeSAl Viro if (err) 17896d7b5aaeSAl Viro break; 1790bd92d7feSAl Viro err = lookup_last(nd, &path); 1791574197e0SAl Viro put_link(nd, &link, cookie); 1792bd92d7feSAl Viro } 1793bd92d7feSAl Viro } 1794ee0827cdSAl Viro 17959f1fafeeSAl Viro if (!err) 17969f1fafeeSAl Viro err = complete_walk(nd); 1797bd92d7feSAl Viro 1798bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 1799bd92d7feSAl Viro if (!nd->inode->i_op->lookup) { 1800bd92d7feSAl Viro path_put(&nd->path); 1801bd23a539SAl Viro err = -ENOTDIR; 1802bd92d7feSAl Viro } 1803bd92d7feSAl Viro } 180416c2cd71SAl Viro 180570e9b357SAl Viro if (base) 180670e9b357SAl Viro fput(base); 1807ee0827cdSAl Viro 18085b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 180931e6b01fSNick Piggin path_put(&nd->root); 181031e6b01fSNick Piggin nd->root.mnt = NULL; 181131e6b01fSNick Piggin } 1812bd92d7feSAl Viro return err; 181331e6b01fSNick Piggin } 181431e6b01fSNick Piggin 1815ee0827cdSAl Viro static int do_path_lookup(int dfd, const char *name, 1816ee0827cdSAl Viro unsigned int flags, struct nameidata *nd) 1817ee0827cdSAl Viro { 1818ee0827cdSAl Viro int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 1819ee0827cdSAl Viro if (unlikely(retval == -ECHILD)) 1820ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags, nd); 1821ee0827cdSAl Viro if (unlikely(retval == -ESTALE)) 1822ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 1823ee0827cdSAl Viro 182431e6b01fSNick Piggin if (likely(!retval)) { 182531e6b01fSNick Piggin if (unlikely(!audit_dummy_context())) { 182631e6b01fSNick Piggin if (nd->path.dentry && nd->inode) 182731e6b01fSNick Piggin audit_inode(name, nd->path.dentry); 182831e6b01fSNick Piggin } 182931e6b01fSNick Piggin } 1830170aa3d0SUlrich Drepper return retval; 18311da177e4SLinus Torvalds } 18321da177e4SLinus Torvalds 1833c9c6cac0SAl Viro int kern_path_parent(const char *name, struct nameidata *nd) 18345590ff0dSUlrich Drepper { 1835c9c6cac0SAl Viro return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd); 18365590ff0dSUlrich Drepper } 18375590ff0dSUlrich Drepper 1838d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 1839d1811465SAl Viro { 1840d1811465SAl Viro struct nameidata nd; 1841d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 1842d1811465SAl Viro if (!res) 1843d1811465SAl Viro *path = nd.path; 1844d1811465SAl Viro return res; 1845d1811465SAl Viro } 1846d1811465SAl Viro 184716f18200SJosef 'Jeff' Sipek /** 184816f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 184916f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 185016f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 185116f18200SJosef 'Jeff' Sipek * @name: pointer to file name 185216f18200SJosef 'Jeff' Sipek * @flags: lookup flags 1853e0a01249SAl Viro * @path: pointer to struct path to fill 185416f18200SJosef 'Jeff' Sipek */ 185516f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 185616f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 1857e0a01249SAl Viro struct path *path) 185816f18200SJosef 'Jeff' Sipek { 1859e0a01249SAl Viro struct nameidata nd; 1860e0a01249SAl Viro int err; 1861e0a01249SAl Viro nd.root.dentry = dentry; 1862e0a01249SAl Viro nd.root.mnt = mnt; 1863e0a01249SAl Viro BUG_ON(flags & LOOKUP_PARENT); 18645b6ca027SAl Viro /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ 1865e0a01249SAl Viro err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd); 1866e0a01249SAl Viro if (!err) 1867e0a01249SAl Viro *path = nd.path; 1868e0a01249SAl Viro return err; 186916f18200SJosef 'Jeff' Sipek } 187016f18200SJosef 'Jeff' Sipek 1871057f6c01SJames Morris /* 1872057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1873057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1874057f6c01SJames Morris * SMP-safe. 1875057f6c01SJames Morris */ 1876a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 18771da177e4SLinus Torvalds { 18784ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 18791da177e4SLinus Torvalds } 18801da177e4SLinus Torvalds 1881eead1911SChristoph Hellwig /** 1882a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1883eead1911SChristoph Hellwig * @name: pathname component to lookup 1884eead1911SChristoph Hellwig * @base: base directory to lookup from 1885eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1886eead1911SChristoph Hellwig * 1887a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1888a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1889eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1890eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1891eead1911SChristoph Hellwig */ 1892057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1893057f6c01SJames Morris { 1894057f6c01SJames Morris struct qstr this; 18956a96ba54SAl Viro unsigned int c; 1896cda309deSMiklos Szeredi int err; 1897057f6c01SJames Morris 18982f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 18992f9092e1SDavid Woodhouse 19006a96ba54SAl Viro this.name = name; 19016a96ba54SAl Viro this.len = len; 19020145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 19036a96ba54SAl Viro if (!len) 19046a96ba54SAl Viro return ERR_PTR(-EACCES); 19056a96ba54SAl Viro 19066a96ba54SAl Viro while (len--) { 19076a96ba54SAl Viro c = *(const unsigned char *)name++; 19086a96ba54SAl Viro if (c == '/' || c == '\0') 19096a96ba54SAl Viro return ERR_PTR(-EACCES); 19106a96ba54SAl Viro } 19115a202bcdSAl Viro /* 19125a202bcdSAl Viro * See if the low-level filesystem might want 19135a202bcdSAl Viro * to use its own hash.. 19145a202bcdSAl Viro */ 19155a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 19165a202bcdSAl Viro int err = base->d_op->d_hash(base, base->d_inode, &this); 19175a202bcdSAl Viro if (err < 0) 19185a202bcdSAl Viro return ERR_PTR(err); 19195a202bcdSAl Viro } 1920eead1911SChristoph Hellwig 1921cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 1922cda309deSMiklos Szeredi if (err) 1923cda309deSMiklos Szeredi return ERR_PTR(err); 1924cda309deSMiklos Szeredi 192549705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1926057f6c01SJames Morris } 1927057f6c01SJames Morris 19281fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 19291fa1e7f6SAndy Whitcroft struct path *path, int *empty) 19301da177e4SLinus Torvalds { 19312d8f3038SAl Viro struct nameidata nd; 19321fa1e7f6SAndy Whitcroft char *tmp = getname_flags(name, flags, empty); 19331da177e4SLinus Torvalds int err = PTR_ERR(tmp); 19341da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 19352d8f3038SAl Viro 19362d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 19372d8f3038SAl Viro 19382d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 19391da177e4SLinus Torvalds putname(tmp); 19402d8f3038SAl Viro if (!err) 19412d8f3038SAl Viro *path = nd.path; 19421da177e4SLinus Torvalds } 19431da177e4SLinus Torvalds return err; 19441da177e4SLinus Torvalds } 19451da177e4SLinus Torvalds 19461fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 19471fa1e7f6SAndy Whitcroft struct path *path) 19481fa1e7f6SAndy Whitcroft { 1949f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 19501fa1e7f6SAndy Whitcroft } 19511fa1e7f6SAndy Whitcroft 19522ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 19532ad94ae6SAl Viro struct nameidata *nd, char **name) 19542ad94ae6SAl Viro { 19552ad94ae6SAl Viro char *s = getname(path); 19562ad94ae6SAl Viro int error; 19572ad94ae6SAl Viro 19582ad94ae6SAl Viro if (IS_ERR(s)) 19592ad94ae6SAl Viro return PTR_ERR(s); 19602ad94ae6SAl Viro 19612ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 19622ad94ae6SAl Viro if (error) 19632ad94ae6SAl Viro putname(s); 19642ad94ae6SAl Viro else 19652ad94ae6SAl Viro *name = s; 19662ad94ae6SAl Viro 19672ad94ae6SAl Viro return error; 19682ad94ae6SAl Viro } 19692ad94ae6SAl Viro 19701da177e4SLinus Torvalds /* 19711da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 19721da177e4SLinus Torvalds * minimal. 19731da177e4SLinus Torvalds */ 19741da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 19751da177e4SLinus Torvalds { 19768e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 1977da9592edSDavid Howells 19781da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 19791da177e4SLinus Torvalds return 0; 19808e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 19811da177e4SLinus Torvalds return 0; 19828e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 19831da177e4SLinus Torvalds return 0; 19841a48e2acSEric W. Biederman return !inode_capable(inode, CAP_FOWNER); 19851da177e4SLinus Torvalds } 19861da177e4SLinus Torvalds 19871da177e4SLinus Torvalds /* 19881da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 19891da177e4SLinus Torvalds * whether the type of victim is right. 19901da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 19911da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 19921da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 19931da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 19941da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 19951da177e4SLinus Torvalds * a. be owner of dir, or 19961da177e4SLinus Torvalds * b. be owner of victim, or 19971da177e4SLinus Torvalds * c. have CAP_FOWNER capability 19981da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 19991da177e4SLinus Torvalds * links pointing to it. 20001da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 20011da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 20021da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 20031da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 20041da177e4SLinus Torvalds * nfs_async_unlink(). 20051da177e4SLinus Torvalds */ 2006858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 20071da177e4SLinus Torvalds { 20081da177e4SLinus Torvalds int error; 20091da177e4SLinus Torvalds 20101da177e4SLinus Torvalds if (!victim->d_inode) 20111da177e4SLinus Torvalds return -ENOENT; 20121da177e4SLinus Torvalds 20131da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 2014cccc6bbaSAl Viro audit_inode_child(victim, dir); 20151da177e4SLinus Torvalds 2016f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 20171da177e4SLinus Torvalds if (error) 20181da177e4SLinus Torvalds return error; 20191da177e4SLinus Torvalds if (IS_APPEND(dir)) 20201da177e4SLinus Torvalds return -EPERM; 20211da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 2022f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 20231da177e4SLinus Torvalds return -EPERM; 20241da177e4SLinus Torvalds if (isdir) { 20251da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 20261da177e4SLinus Torvalds return -ENOTDIR; 20271da177e4SLinus Torvalds if (IS_ROOT(victim)) 20281da177e4SLinus Torvalds return -EBUSY; 20291da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 20301da177e4SLinus Torvalds return -EISDIR; 20311da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 20321da177e4SLinus Torvalds return -ENOENT; 20331da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 20341da177e4SLinus Torvalds return -EBUSY; 20351da177e4SLinus Torvalds return 0; 20361da177e4SLinus Torvalds } 20371da177e4SLinus Torvalds 20381da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 20391da177e4SLinus Torvalds * dir. 20401da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 20411da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 20421da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 20431da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 20441da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 20451da177e4SLinus Torvalds */ 2046a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 20471da177e4SLinus Torvalds { 20481da177e4SLinus Torvalds if (child->d_inode) 20491da177e4SLinus Torvalds return -EEXIST; 20501da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 20511da177e4SLinus Torvalds return -ENOENT; 2052f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 20531da177e4SLinus Torvalds } 20541da177e4SLinus Torvalds 20551da177e4SLinus Torvalds /* 20561da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 20571da177e4SLinus Torvalds */ 20581da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 20591da177e4SLinus Torvalds { 20601da177e4SLinus Torvalds struct dentry *p; 20611da177e4SLinus Torvalds 20621da177e4SLinus Torvalds if (p1 == p2) { 2063f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 20641da177e4SLinus Torvalds return NULL; 20651da177e4SLinus Torvalds } 20661da177e4SLinus Torvalds 2067a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 20681da177e4SLinus Torvalds 2069e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2070e2761a11SOGAWA Hirofumi if (p) { 2071f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2072f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 20731da177e4SLinus Torvalds return p; 20741da177e4SLinus Torvalds } 20751da177e4SLinus Torvalds 2076e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2077e2761a11SOGAWA Hirofumi if (p) { 2078f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2079f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 20801da177e4SLinus Torvalds return p; 20811da177e4SLinus Torvalds } 20821da177e4SLinus Torvalds 2083f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2084f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 20851da177e4SLinus Torvalds return NULL; 20861da177e4SLinus Torvalds } 20871da177e4SLinus Torvalds 20881da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 20891da177e4SLinus Torvalds { 20901b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 20911da177e4SLinus Torvalds if (p1 != p2) { 20921b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2093a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 20941da177e4SLinus Torvalds } 20951da177e4SLinus Torvalds } 20961da177e4SLinus Torvalds 20974acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 20981da177e4SLinus Torvalds struct nameidata *nd) 20991da177e4SLinus Torvalds { 2100a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 21011da177e4SLinus Torvalds 21021da177e4SLinus Torvalds if (error) 21031da177e4SLinus Torvalds return error; 21041da177e4SLinus Torvalds 2105acfa4380SAl Viro if (!dir->i_op->create) 21061da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 21071da177e4SLinus Torvalds mode &= S_IALLUGO; 21081da177e4SLinus Torvalds mode |= S_IFREG; 21091da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 21101da177e4SLinus Torvalds if (error) 21111da177e4SLinus Torvalds return error; 21121da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 2113a74574aaSStephen Smalley if (!error) 2114f38aa942SAmy Griffis fsnotify_create(dir, dentry); 21151da177e4SLinus Torvalds return error; 21161da177e4SLinus Torvalds } 21171da177e4SLinus Torvalds 211873d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 21191da177e4SLinus Torvalds { 21203fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 21211da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 21221da177e4SLinus Torvalds int error; 21231da177e4SLinus Torvalds 2124bcda7652SAl Viro /* O_PATH? */ 2125bcda7652SAl Viro if (!acc_mode) 2126bcda7652SAl Viro return 0; 2127bcda7652SAl Viro 21281da177e4SLinus Torvalds if (!inode) 21291da177e4SLinus Torvalds return -ENOENT; 21301da177e4SLinus Torvalds 2131c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2132c8fe8f30SChristoph Hellwig case S_IFLNK: 21331da177e4SLinus Torvalds return -ELOOP; 2134c8fe8f30SChristoph Hellwig case S_IFDIR: 2135c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 21361da177e4SLinus Torvalds return -EISDIR; 2137c8fe8f30SChristoph Hellwig break; 2138c8fe8f30SChristoph Hellwig case S_IFBLK: 2139c8fe8f30SChristoph Hellwig case S_IFCHR: 21403fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 21411da177e4SLinus Torvalds return -EACCES; 2142c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2143c8fe8f30SChristoph Hellwig case S_IFIFO: 2144c8fe8f30SChristoph Hellwig case S_IFSOCK: 21451da177e4SLinus Torvalds flag &= ~O_TRUNC; 2146c8fe8f30SChristoph Hellwig break; 21474a3fd211SDave Hansen } 2148b41572e9SDave Hansen 21493fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2150b41572e9SDave Hansen if (error) 2151b41572e9SDave Hansen return error; 21526146f0d5SMimi Zohar 21531da177e4SLinus Torvalds /* 21541da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 21551da177e4SLinus Torvalds */ 21561da177e4SLinus Torvalds if (IS_APPEND(inode)) { 21578737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 21587715b521SAl Viro return -EPERM; 21591da177e4SLinus Torvalds if (flag & O_TRUNC) 21607715b521SAl Viro return -EPERM; 21611da177e4SLinus Torvalds } 21621da177e4SLinus Torvalds 21631da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 21642e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 21657715b521SAl Viro return -EPERM; 21661da177e4SLinus Torvalds 2167f3c7691eSJ. Bruce Fields return 0; 21687715b521SAl Viro } 21697715b521SAl Viro 2170e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 21717715b521SAl Viro { 2172e1181ee6SJeff Layton struct path *path = &filp->f_path; 21737715b521SAl Viro struct inode *inode = path->dentry->d_inode; 21747715b521SAl Viro int error = get_write_access(inode); 21751da177e4SLinus Torvalds if (error) 21767715b521SAl Viro return error; 21771da177e4SLinus Torvalds /* 21781da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 21791da177e4SLinus Torvalds */ 21801da177e4SLinus Torvalds error = locks_verify_locked(inode); 2181be6d3e56SKentaro Takeda if (!error) 2182ea0d3ab2STetsuo Handa error = security_path_truncate(path); 21831da177e4SLinus Torvalds if (!error) { 21847715b521SAl Viro error = do_truncate(path->dentry, 0, 2185d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2186e1181ee6SJeff Layton filp); 21871da177e4SLinus Torvalds } 21881da177e4SLinus Torvalds put_write_access(inode); 2189acd0c935SMimi Zohar return error; 21901da177e4SLinus Torvalds } 21911da177e4SLinus Torvalds 2192d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2193d57999e1SDave Hansen { 21948a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 21958a5e929dSAl Viro flag--; 2196d57999e1SDave Hansen return flag; 2197d57999e1SDave Hansen } 2198d57999e1SDave Hansen 2199d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2200d18e9008SMiklos Szeredi { 2201d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2202d18e9008SMiklos Szeredi if (error) 2203d18e9008SMiklos Szeredi return error; 2204d18e9008SMiklos Szeredi 2205d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2206d18e9008SMiklos Szeredi if (error) 2207d18e9008SMiklos Szeredi return error; 2208d18e9008SMiklos Szeredi 2209d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2210d18e9008SMiklos Szeredi } 2211d18e9008SMiklos Szeredi 2212d18e9008SMiklos Szeredi static struct file *atomic_open(struct nameidata *nd, struct dentry *dentry, 2213d18e9008SMiklos Szeredi struct path *path, const struct open_flags *op, 2214d18e9008SMiklos Szeredi int *want_write, bool need_lookup, 2215d18e9008SMiklos Szeredi bool *created) 2216d18e9008SMiklos Szeredi { 2217d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2218d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2219d18e9008SMiklos Szeredi umode_t mode; 2220d18e9008SMiklos Szeredi int error; 2221d18e9008SMiklos Szeredi int acc_mode; 2222d18e9008SMiklos Szeredi struct opendata od; 2223d18e9008SMiklos Szeredi struct file *filp; 2224d18e9008SMiklos Szeredi int create_error = 0; 2225d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2226d18e9008SMiklos Szeredi 2227d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2228d18e9008SMiklos Szeredi 2229d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2230d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 2231d18e9008SMiklos Szeredi filp = ERR_PTR(-ENOENT); 2232d18e9008SMiklos Szeredi goto out; 2233d18e9008SMiklos Szeredi } 2234d18e9008SMiklos Szeredi 2235d18e9008SMiklos Szeredi mode = op->mode & S_IALLUGO; 2236d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2237d18e9008SMiklos Szeredi mode &= ~current_umask(); 2238d18e9008SMiklos Szeredi 2239d18e9008SMiklos Szeredi if (open_flag & O_EXCL) { 2240d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2241d18e9008SMiklos Szeredi *created = true; 2242d18e9008SMiklos Szeredi } 2243d18e9008SMiklos Szeredi 2244d18e9008SMiklos Szeredi /* 2245d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2246d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2247d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2248d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2249d18e9008SMiklos Szeredi * 2250d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2251d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2252d18e9008SMiklos Szeredi */ 2253d18e9008SMiklos Szeredi if ((open_flag & (O_CREAT | O_TRUNC)) || 2254d18e9008SMiklos Szeredi (open_flag & O_ACCMODE) != O_RDONLY) { 2255d18e9008SMiklos Szeredi error = mnt_want_write(nd->path.mnt); 2256d18e9008SMiklos Szeredi if (!error) { 2257d18e9008SMiklos Szeredi *want_write = 1; 2258d18e9008SMiklos Szeredi } else if (!(open_flag & O_CREAT)) { 2259d18e9008SMiklos Szeredi /* 2260d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2261d18e9008SMiklos Szeredi * back to lookup + open 2262d18e9008SMiklos Szeredi */ 2263d18e9008SMiklos Szeredi goto no_open; 2264d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2265d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 2266d18e9008SMiklos Szeredi create_error = error; 2267d18e9008SMiklos Szeredi goto no_open; 2268d18e9008SMiklos Szeredi } else { 2269d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 2270d18e9008SMiklos Szeredi create_error = error; 2271d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2272d18e9008SMiklos Szeredi } 2273d18e9008SMiklos Szeredi } 2274d18e9008SMiklos Szeredi 2275d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 2276d18e9008SMiklos Szeredi error = may_o_create(&nd->path, dentry, op->mode); 2277d18e9008SMiklos Szeredi if (error) { 2278d18e9008SMiklos Szeredi create_error = error; 2279d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2280d18e9008SMiklos Szeredi goto no_open; 2281d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2282d18e9008SMiklos Szeredi } 2283d18e9008SMiklos Szeredi } 2284d18e9008SMiklos Szeredi 2285d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2286d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2287d18e9008SMiklos Szeredi 2288d18e9008SMiklos Szeredi od.dentry = DENTRY_NOT_SET; 2289d18e9008SMiklos Szeredi od.mnt = nd->path.mnt; 2290d18e9008SMiklos Szeredi od.filp = &nd->intent.open.file; 2291d18e9008SMiklos Szeredi filp = dir->i_op->atomic_open(dir, dentry, &od, open_flag, mode, 2292d18e9008SMiklos Szeredi created); 2293d18e9008SMiklos Szeredi if (IS_ERR(filp)) { 2294d18e9008SMiklos Szeredi if (WARN_ON(od.dentry != DENTRY_NOT_SET)) 2295d18e9008SMiklos Szeredi dput(od.dentry); 2296d18e9008SMiklos Szeredi 2297d18e9008SMiklos Szeredi if (create_error && PTR_ERR(filp) == -ENOENT) 2298d18e9008SMiklos Szeredi filp = ERR_PTR(create_error); 2299d18e9008SMiklos Szeredi goto out; 2300d18e9008SMiklos Szeredi } 2301d18e9008SMiklos Szeredi 2302d18e9008SMiklos Szeredi acc_mode = op->acc_mode; 2303d18e9008SMiklos Szeredi if (*created) { 2304d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 2305d18e9008SMiklos Szeredi acc_mode = MAY_OPEN; 2306d18e9008SMiklos Szeredi } 2307d18e9008SMiklos Szeredi 2308d18e9008SMiklos Szeredi if (!filp) { 2309d18e9008SMiklos Szeredi if (WARN_ON(od.dentry == DENTRY_NOT_SET)) { 2310d18e9008SMiklos Szeredi filp = ERR_PTR(-EIO); 2311d18e9008SMiklos Szeredi goto out; 2312d18e9008SMiklos Szeredi } 2313d18e9008SMiklos Szeredi if (od.dentry) { 2314d18e9008SMiklos Szeredi dput(dentry); 2315d18e9008SMiklos Szeredi dentry = od.dentry; 2316d18e9008SMiklos Szeredi } 2317d18e9008SMiklos Szeredi goto looked_up; 2318d18e9008SMiklos Szeredi } 2319d18e9008SMiklos Szeredi 2320d18e9008SMiklos Szeredi /* 2321d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2322d18e9008SMiklos Szeredi * here. 2323d18e9008SMiklos Szeredi */ 2324d18e9008SMiklos Szeredi error = may_open(&filp->f_path, acc_mode, open_flag); 2325d18e9008SMiklos Szeredi if (error) 2326d18e9008SMiklos Szeredi goto out_fput; 2327d18e9008SMiklos Szeredi 2328d18e9008SMiklos Szeredi error = open_check_o_direct(filp); 2329d18e9008SMiklos Szeredi if (error) 2330d18e9008SMiklos Szeredi goto out_fput; 2331d18e9008SMiklos Szeredi 2332d18e9008SMiklos Szeredi out: 2333d18e9008SMiklos Szeredi dput(dentry); 2334d18e9008SMiklos Szeredi return filp; 2335d18e9008SMiklos Szeredi 2336d18e9008SMiklos Szeredi out_fput: 2337d18e9008SMiklos Szeredi fput(filp); 2338d18e9008SMiklos Szeredi filp = ERR_PTR(error); 2339d18e9008SMiklos Szeredi goto out; 2340d18e9008SMiklos Szeredi 2341d18e9008SMiklos Szeredi no_open: 2342d18e9008SMiklos Szeredi if (need_lookup) { 2343d18e9008SMiklos Szeredi dentry = lookup_real(dir, dentry, nd); 2344d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 2345d18e9008SMiklos Szeredi return ERR_CAST(dentry); 2346d18e9008SMiklos Szeredi 2347d18e9008SMiklos Szeredi if (create_error) { 2348d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2349d18e9008SMiklos Szeredi 2350d18e9008SMiklos Szeredi filp = ERR_PTR(create_error); 2351d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2352d18e9008SMiklos Szeredi if (!dentry->d_inode) 2353d18e9008SMiklos Szeredi goto out; 2354d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2355d18e9008SMiklos Szeredi goto out; 2356d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2357d18e9008SMiklos Szeredi S_ISREG(dentry->d_inode->i_mode)) { 2358d18e9008SMiklos Szeredi goto out; 2359d18e9008SMiklos Szeredi } 2360d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2361d18e9008SMiklos Szeredi } 2362d18e9008SMiklos Szeredi } 2363d18e9008SMiklos Szeredi looked_up: 2364d18e9008SMiklos Szeredi path->dentry = dentry; 2365d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 2366d18e9008SMiklos Szeredi return NULL; 2367d18e9008SMiklos Szeredi } 2368d18e9008SMiklos Szeredi 236931e6b01fSNick Piggin /* 2370d58ffd35SMiklos Szeredi * Lookup, maybe create and open the last component 2371d58ffd35SMiklos Szeredi * 2372d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2373d58ffd35SMiklos Szeredi * 2374d58ffd35SMiklos Szeredi * Returns open file or NULL on success, error otherwise. NULL means no open 2375d58ffd35SMiklos Szeredi * was performed, only lookup. 2376d58ffd35SMiklos Szeredi */ 2377d58ffd35SMiklos Szeredi static struct file *lookup_open(struct nameidata *nd, struct path *path, 2378d58ffd35SMiklos Szeredi const struct open_flags *op, 2379d58ffd35SMiklos Szeredi int *want_write, bool *created) 2380d58ffd35SMiklos Szeredi { 2381d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 238254ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2383d58ffd35SMiklos Szeredi struct dentry *dentry; 2384d58ffd35SMiklos Szeredi int error; 238554ef4872SMiklos Szeredi bool need_lookup; 2386d58ffd35SMiklos Szeredi 2387d58ffd35SMiklos Szeredi *created = false; 238854ef4872SMiklos Szeredi dentry = lookup_dcache(&nd->last, dir, nd, &need_lookup); 2389d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 2390d58ffd35SMiklos Szeredi return ERR_CAST(dentry); 2391d58ffd35SMiklos Szeredi 2392d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2393d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2394d18e9008SMiklos Szeredi goto out_no_open; 2395d18e9008SMiklos Szeredi 2396d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 2397d18e9008SMiklos Szeredi return atomic_open(nd, dentry, path, op, want_write, 2398d18e9008SMiklos Szeredi need_lookup, created); 2399d18e9008SMiklos Szeredi } 2400d18e9008SMiklos Szeredi 240154ef4872SMiklos Szeredi if (need_lookup) { 240254ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 240354ef4872SMiklos Szeredi 240454ef4872SMiklos Szeredi dentry = lookup_real(dir_inode, dentry, nd); 240554ef4872SMiklos Szeredi if (IS_ERR(dentry)) 240654ef4872SMiklos Szeredi return ERR_CAST(dentry); 240754ef4872SMiklos Szeredi } 240854ef4872SMiklos Szeredi 2409d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2410d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2411d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2412d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2413d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2414d58ffd35SMiklos Szeredi /* 2415d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2416d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2417d58ffd35SMiklos Szeredi * the time when the file is created and when 2418d58ffd35SMiklos Szeredi * a permanent write count is taken through 2419d58ffd35SMiklos Szeredi * the 'struct file' in nameidata_to_filp(). 2420d58ffd35SMiklos Szeredi */ 2421d58ffd35SMiklos Szeredi error = mnt_want_write(nd->path.mnt); 2422d58ffd35SMiklos Szeredi if (error) 2423d58ffd35SMiklos Szeredi goto out_dput; 2424d58ffd35SMiklos Szeredi *want_write = 1; 2425d58ffd35SMiklos Szeredi *created = true; 2426d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2427d58ffd35SMiklos Szeredi if (error) 2428d58ffd35SMiklos Szeredi goto out_dput; 2429d58ffd35SMiklos Szeredi error = vfs_create(dir->d_inode, dentry, mode, nd); 2430d58ffd35SMiklos Szeredi if (error) 2431d58ffd35SMiklos Szeredi goto out_dput; 2432d58ffd35SMiklos Szeredi } 2433d18e9008SMiklos Szeredi out_no_open: 2434d58ffd35SMiklos Szeredi path->dentry = dentry; 2435d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 2436d58ffd35SMiklos Szeredi return NULL; 2437d58ffd35SMiklos Szeredi 2438d58ffd35SMiklos Szeredi out_dput: 2439d58ffd35SMiklos Szeredi dput(dentry); 2440d58ffd35SMiklos Szeredi return ERR_PTR(error); 2441d58ffd35SMiklos Szeredi } 2442d58ffd35SMiklos Szeredi 2443d58ffd35SMiklos Szeredi /* 2444fe2d35ffSAl Viro * Handle the last step of open() 244531e6b01fSNick Piggin */ 2446fb1cc555SAl Viro static struct file *do_last(struct nameidata *nd, struct path *path, 2447c3e380b0SAl Viro const struct open_flags *op, const char *pathname) 2448fb1cc555SAl Viro { 2449a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2450ca344a89SAl Viro int open_flag = op->open_flag; 24516c0d46c4SAl Viro int will_truncate = open_flag & O_TRUNC; 2452ca344a89SAl Viro int want_write = 0; 2453bcda7652SAl Viro int acc_mode = op->acc_mode; 2454fb1cc555SAl Viro struct file *filp; 2455a1eb3315SMiklos Szeredi struct inode *inode; 2456d58ffd35SMiklos Szeredi bool created; 2457d45ea867SMiklos Szeredi int symlink_ok = 0; 245816b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 245916b1c1cdSMiklos Szeredi bool retried = false; 246016c2cd71SAl Viro int error; 2461fb1cc555SAl Viro 2462c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2463c3e380b0SAl Viro nd->flags |= op->intent; 2464c3e380b0SAl Viro 24651f36f774SAl Viro switch (nd->last_type) { 24661f36f774SAl Viro case LAST_DOTDOT: 2467176306f5SNeil Brown case LAST_DOT: 2468fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2469fe2d35ffSAl Viro if (error) 2470fe2d35ffSAl Viro return ERR_PTR(error); 24711f36f774SAl Viro /* fallthrough */ 24721f36f774SAl Viro case LAST_ROOT: 24739f1fafeeSAl Viro error = complete_walk(nd); 247416c2cd71SAl Viro if (error) 24759f1fafeeSAl Viro return ERR_PTR(error); 2476fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2477ca344a89SAl Viro if (open_flag & O_CREAT) { 247816c2cd71SAl Viro error = -EISDIR; 24791f36f774SAl Viro goto exit; 2480fe2d35ffSAl Viro } 2481fe2d35ffSAl Viro goto ok; 24821f36f774SAl Viro case LAST_BIND: 24839f1fafeeSAl Viro error = complete_walk(nd); 248416c2cd71SAl Viro if (error) 24859f1fafeeSAl Viro return ERR_PTR(error); 24861f36f774SAl Viro audit_inode(pathname, dir); 24871f36f774SAl Viro goto ok; 24881f36f774SAl Viro } 2489a2c36b45SAl Viro 2490ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2491fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2492fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2493bcda7652SAl Viro if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) 2494bcda7652SAl Viro symlink_ok = 1; 2495fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2496a1eb3315SMiklos Szeredi error = lookup_fast(nd, &nd->last, path, &inode); 249771574865SMiklos Szeredi if (likely(!error)) 249871574865SMiklos Szeredi goto finish_lookup; 249971574865SMiklos Szeredi 2500ce57dfc1SAl Viro if (error < 0) 2501a1eb3315SMiklos Szeredi goto exit; 2502a1eb3315SMiklos Szeredi 250337d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 2504b6183df7SMiklos Szeredi } else { 2505fe2d35ffSAl Viro /* create side of things */ 2506a3fbbde7SAl Viro /* 2507b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 2508b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 2509b6183df7SMiklos Szeredi * about to look up 2510a3fbbde7SAl Viro */ 25119f1fafeeSAl Viro error = complete_walk(nd); 25129f1fafeeSAl Viro if (error) 25139f1fafeeSAl Viro return ERR_PTR(error); 2514fe2d35ffSAl Viro 2515fe2d35ffSAl Viro audit_inode(pathname, dir); 251616c2cd71SAl Viro error = -EISDIR; 25171f36f774SAl Viro /* trailing slashes? */ 251831e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 25191f36f774SAl Viro goto exit; 2520b6183df7SMiklos Szeredi } 25211f36f774SAl Viro 252216b1c1cdSMiklos Szeredi retry_lookup: 2523a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 2524d58ffd35SMiklos Szeredi filp = lookup_open(nd, path, op, &want_write, &created); 2525fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2526fb1cc555SAl Viro 2527d18e9008SMiklos Szeredi if (filp) { 2528d58ffd35SMiklos Szeredi if (IS_ERR(filp)) 2529d58ffd35SMiklos Szeredi goto out; 25306c0d46c4SAl Viro 2531d18e9008SMiklos Szeredi if (created || !S_ISREG(filp->f_path.dentry->d_inode->i_mode)) 2532d18e9008SMiklos Szeredi will_truncate = 0; 2533d18e9008SMiklos Szeredi 2534d18e9008SMiklos Szeredi audit_inode(pathname, filp->f_path.dentry); 2535d18e9008SMiklos Szeredi goto opened; 2536d18e9008SMiklos Szeredi } 2537d18e9008SMiklos Szeredi 2538d58ffd35SMiklos Szeredi if (created) { 25399b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 2540ca344a89SAl Viro open_flag &= ~O_TRUNC; 25416c0d46c4SAl Viro will_truncate = 0; 2542bcda7652SAl Viro acc_mode = MAY_OPEN; 2543d58ffd35SMiklos Szeredi path_to_nameidata(path, nd); 2544ca344a89SAl Viro goto common; 2545fb1cc555SAl Viro } 2546fb1cc555SAl Viro 2547fb1cc555SAl Viro /* 2548fb1cc555SAl Viro * It already exists. 2549fb1cc555SAl Viro */ 2550fb1cc555SAl Viro audit_inode(pathname, path->dentry); 2551fb1cc555SAl Viro 2552d18e9008SMiklos Szeredi /* 2553d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 2554d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 2555d18e9008SMiklos Szeredi * necessary...) 2556d18e9008SMiklos Szeredi */ 2557d18e9008SMiklos Szeredi if (want_write) { 2558d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 2559d18e9008SMiklos Szeredi want_write = 0; 2560d18e9008SMiklos Szeredi } 2561d18e9008SMiklos Szeredi 2562fb1cc555SAl Viro error = -EEXIST; 2563ca344a89SAl Viro if (open_flag & O_EXCL) 2564fb1cc555SAl Viro goto exit_dput; 2565fb1cc555SAl Viro 25669875cf80SDavid Howells error = follow_managed(path, nd->flags); 25679875cf80SDavid Howells if (error < 0) 2568fb1cc555SAl Viro goto exit_dput; 2569fb1cc555SAl Viro 2570a3fbbde7SAl Viro if (error) 2571a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 2572a3fbbde7SAl Viro 2573decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 2574decf3400SMiklos Szeredi inode = path->dentry->d_inode; 25755f5daac1SMiklos Szeredi finish_lookup: 25765f5daac1SMiklos Szeredi /* we _can_ be in RCU mode here */ 2577fb1cc555SAl Viro error = -ENOENT; 257854c33e7fSMiklos Szeredi if (!inode) { 257954c33e7fSMiklos Szeredi path_to_nameidata(path, nd); 258054c33e7fSMiklos Szeredi goto exit; 258154c33e7fSMiklos Szeredi } 25829e67f361SAl Viro 2583d45ea867SMiklos Szeredi if (should_follow_link(inode, !symlink_ok)) { 2584d45ea867SMiklos Szeredi if (nd->flags & LOOKUP_RCU) { 2585d45ea867SMiklos Szeredi if (unlikely(unlazy_walk(nd, path->dentry))) { 2586d45ea867SMiklos Szeredi error = -ECHILD; 2587d45ea867SMiklos Szeredi goto exit; 2588d45ea867SMiklos Szeredi } 2589d45ea867SMiklos Szeredi } 2590d45ea867SMiklos Szeredi BUG_ON(inode != path->dentry->d_inode); 2591fb1cc555SAl Viro return NULL; 2592d45ea867SMiklos Szeredi } 2593fb1cc555SAl Viro 259416b1c1cdSMiklos Szeredi if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path->mnt) { 2595fb1cc555SAl Viro path_to_nameidata(path, nd); 259616b1c1cdSMiklos Szeredi } else { 259716b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 259816b1c1cdSMiklos Szeredi save_parent.mnt = mntget(path->mnt); 259916b1c1cdSMiklos Szeredi nd->path.dentry = path->dentry; 260016b1c1cdSMiklos Szeredi 260116b1c1cdSMiklos Szeredi } 2602decf3400SMiklos Szeredi nd->inode = inode; 2603a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 2604a3fbbde7SAl Viro error = complete_walk(nd); 260516b1c1cdSMiklos Szeredi if (error) { 260616b1c1cdSMiklos Szeredi path_put(&save_parent); 2607097b180cSMiklos Szeredi return ERR_PTR(error); 260816b1c1cdSMiklos Szeredi } 2609fb1cc555SAl Viro error = -EISDIR; 2610050ac841SMiklos Szeredi if ((open_flag & O_CREAT) && S_ISDIR(nd->inode->i_mode)) 2611fb1cc555SAl Viro goto exit; 2612af2f5542SMiklos Szeredi error = -ENOTDIR; 2613af2f5542SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !nd->inode->i_op->lookup) 2614af2f5542SMiklos Szeredi goto exit; 2615d7fdd7f6SMiklos Szeredi audit_inode(pathname, nd->path.dentry); 261667ee3ad2SAl Viro ok: 26176c0d46c4SAl Viro if (!S_ISREG(nd->inode->i_mode)) 26186c0d46c4SAl Viro will_truncate = 0; 26196c0d46c4SAl Viro 26200f9d1a10SAl Viro if (will_truncate) { 26210f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 26220f9d1a10SAl Viro if (error) 26230f9d1a10SAl Viro goto exit; 2624ca344a89SAl Viro want_write = 1; 26250f9d1a10SAl Viro } 2626ca344a89SAl Viro common: 2627bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 2628ca344a89SAl Viro if (error) 26290f9d1a10SAl Viro goto exit; 26300f9d1a10SAl Viro filp = nameidata_to_filp(nd); 263116b1c1cdSMiklos Szeredi if (filp == ERR_PTR(-EOPENSTALE) && save_parent.dentry && !retried) { 263216b1c1cdSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 263316b1c1cdSMiklos Szeredi path_put(&nd->path); 263416b1c1cdSMiklos Szeredi nd->path = save_parent; 263516b1c1cdSMiklos Szeredi nd->inode = dir->d_inode; 263616b1c1cdSMiklos Szeredi save_parent.mnt = NULL; 263716b1c1cdSMiklos Szeredi save_parent.dentry = NULL; 263816b1c1cdSMiklos Szeredi if (want_write) { 263916b1c1cdSMiklos Szeredi mnt_drop_write(nd->path.mnt); 264016b1c1cdSMiklos Szeredi want_write = 0; 264116b1c1cdSMiklos Szeredi } 264216b1c1cdSMiklos Szeredi retried = true; 264316b1c1cdSMiklos Szeredi goto retry_lookup; 264416b1c1cdSMiklos Szeredi } 2645d18e9008SMiklos Szeredi opened: 26460f9d1a10SAl Viro if (!IS_ERR(filp)) { 26470f9d1a10SAl Viro error = ima_file_check(filp, op->acc_mode); 26480f9d1a10SAl Viro if (error) { 26490f9d1a10SAl Viro fput(filp); 26500f9d1a10SAl Viro filp = ERR_PTR(error); 26510f9d1a10SAl Viro } 26520f9d1a10SAl Viro } 26530f9d1a10SAl Viro if (!IS_ERR(filp)) { 26540f9d1a10SAl Viro if (will_truncate) { 26550f9d1a10SAl Viro error = handle_truncate(filp); 26560f9d1a10SAl Viro if (error) { 26570f9d1a10SAl Viro fput(filp); 26580f9d1a10SAl Viro filp = ERR_PTR(error); 26590f9d1a10SAl Viro } 26600f9d1a10SAl Viro } 26610f9d1a10SAl Viro } 2662ca344a89SAl Viro out: 2663ca344a89SAl Viro if (want_write) 26640f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 266516b1c1cdSMiklos Szeredi path_put(&save_parent); 2666e276ae67SMiklos Szeredi terminate_walk(nd); 2667fb1cc555SAl Viro return filp; 2668fb1cc555SAl Viro 2669fb1cc555SAl Viro exit_dput: 2670fb1cc555SAl Viro path_put_conditional(path, nd); 2671fb1cc555SAl Viro exit: 2672ca344a89SAl Viro filp = ERR_PTR(error); 2673ca344a89SAl Viro goto out; 2674fb1cc555SAl Viro } 2675fb1cc555SAl Viro 267613aab428SAl Viro static struct file *path_openat(int dfd, const char *pathname, 267773d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 26781da177e4SLinus Torvalds { 2679fe2d35ffSAl Viro struct file *base = NULL; 26804a3fd211SDave Hansen struct file *filp; 26819850c056SAl Viro struct path path; 268213aab428SAl Viro int error; 268331e6b01fSNick Piggin 268431e6b01fSNick Piggin filp = get_empty_filp(); 268531e6b01fSNick Piggin if (!filp) 268631e6b01fSNick Piggin return ERR_PTR(-ENFILE); 268731e6b01fSNick Piggin 268847c805dcSAl Viro filp->f_flags = op->open_flag; 268973d049a4SAl Viro nd->intent.open.file = filp; 269073d049a4SAl Viro nd->intent.open.flags = open_to_namei_flags(op->open_flag); 269173d049a4SAl Viro nd->intent.open.create_mode = op->mode; 269231e6b01fSNick Piggin 269373d049a4SAl Viro error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base); 269431e6b01fSNick Piggin if (unlikely(error)) 269513aab428SAl Viro goto out_filp; 269631e6b01fSNick Piggin 2697fe2d35ffSAl Viro current->total_link_count = 0; 269873d049a4SAl Viro error = link_path_walk(pathname, nd); 269931e6b01fSNick Piggin if (unlikely(error)) 270031e6b01fSNick Piggin goto out_filp; 27011da177e4SLinus Torvalds 270273d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2703806b681cSAl Viro while (unlikely(!filp)) { /* trailing symlink */ 27047b9337aaSNick Piggin struct path link = path; 2705def4af30SAl Viro void *cookie; 2706574197e0SAl Viro if (!(nd->flags & LOOKUP_FOLLOW)) { 270773d049a4SAl Viro path_put_conditional(&path, nd); 270873d049a4SAl Viro path_put(&nd->path); 270940b39136SAl Viro filp = ERR_PTR(-ELOOP); 271040b39136SAl Viro break; 271140b39136SAl Viro } 271273d049a4SAl Viro nd->flags |= LOOKUP_PARENT; 271373d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 2714574197e0SAl Viro error = follow_link(&link, nd, &cookie); 2715c3e380b0SAl Viro if (unlikely(error)) 27166d7b5aaeSAl Viro goto out_filp; 271773d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2718574197e0SAl Viro put_link(nd, &link, cookie); 2719806b681cSAl Viro } 272010fa8e62SAl Viro out: 272173d049a4SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) 272273d049a4SAl Viro path_put(&nd->root); 2723fe2d35ffSAl Viro if (base) 2724fe2d35ffSAl Viro fput(base); 272573d049a4SAl Viro release_open_intent(nd); 272616b1c1cdSMiklos Szeredi if (filp == ERR_PTR(-EOPENSTALE)) { 272716b1c1cdSMiklos Szeredi if (flags & LOOKUP_RCU) 272816b1c1cdSMiklos Szeredi filp = ERR_PTR(-ECHILD); 272916b1c1cdSMiklos Szeredi else 273016b1c1cdSMiklos Szeredi filp = ERR_PTR(-ESTALE); 273116b1c1cdSMiklos Szeredi } 273210fa8e62SAl Viro return filp; 27331da177e4SLinus Torvalds 273431e6b01fSNick Piggin out_filp: 273510fa8e62SAl Viro filp = ERR_PTR(error); 273610fa8e62SAl Viro goto out; 2737de459215SKirill Korotaev } 27381da177e4SLinus Torvalds 273913aab428SAl Viro struct file *do_filp_open(int dfd, const char *pathname, 274013aab428SAl Viro const struct open_flags *op, int flags) 274113aab428SAl Viro { 274273d049a4SAl Viro struct nameidata nd; 274313aab428SAl Viro struct file *filp; 274413aab428SAl Viro 274573d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 274613aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 274773d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 274813aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 274973d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 275013aab428SAl Viro return filp; 275113aab428SAl Viro } 275213aab428SAl Viro 275373d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 275473d049a4SAl Viro const char *name, const struct open_flags *op, int flags) 275573d049a4SAl Viro { 275673d049a4SAl Viro struct nameidata nd; 275773d049a4SAl Viro struct file *file; 275873d049a4SAl Viro 275973d049a4SAl Viro nd.root.mnt = mnt; 276073d049a4SAl Viro nd.root.dentry = dentry; 276173d049a4SAl Viro 276273d049a4SAl Viro flags |= LOOKUP_ROOT; 276373d049a4SAl Viro 2764bcda7652SAl Viro if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) 276573d049a4SAl Viro return ERR_PTR(-ELOOP); 276673d049a4SAl Viro 276773d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU); 276873d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 276973d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags); 277073d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 277173d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL); 277273d049a4SAl Viro return file; 277373d049a4SAl Viro } 277473d049a4SAl Viro 2775ed75e95dSAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, int is_dir) 27761da177e4SLinus Torvalds { 2777c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 2778ed75e95dSAl Viro struct nameidata nd; 2779ed75e95dSAl Viro int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd); 2780ed75e95dSAl Viro if (error) 2781ed75e95dSAl Viro return ERR_PTR(error); 27821da177e4SLinus Torvalds 2783c663e5d8SChristoph Hellwig /* 2784c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 2785c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 2786c663e5d8SChristoph Hellwig */ 2787ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 2788ed75e95dSAl Viro goto out; 2789ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 2790ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 2791ed75e95dSAl Viro nd.intent.open.flags = O_EXCL; 2792c663e5d8SChristoph Hellwig 2793c663e5d8SChristoph Hellwig /* 2794c663e5d8SChristoph Hellwig * Do the final lookup. 2795c663e5d8SChristoph Hellwig */ 2796ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 2797ed75e95dSAl Viro dentry = lookup_hash(&nd); 27981da177e4SLinus Torvalds if (IS_ERR(dentry)) 27991da177e4SLinus Torvalds goto fail; 2800c663e5d8SChristoph Hellwig 2801e9baf6e5SAl Viro if (dentry->d_inode) 2802e9baf6e5SAl Viro goto eexist; 2803c663e5d8SChristoph Hellwig /* 2804c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 2805c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 2806c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 2807c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 2808c663e5d8SChristoph Hellwig */ 2809ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 28101da177e4SLinus Torvalds dput(dentry); 28111da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 2812ed75e95dSAl Viro goto fail; 2813e9baf6e5SAl Viro } 2814ed75e95dSAl Viro *path = nd.path; 2815e9baf6e5SAl Viro return dentry; 2816e9baf6e5SAl Viro eexist: 2817e9baf6e5SAl Viro dput(dentry); 2818e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 28191da177e4SLinus Torvalds fail: 2820dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 2821ed75e95dSAl Viro out: 2822dae6ad8fSAl Viro path_put(&nd.path); 2823ed75e95dSAl Viro return dentry; 2824dae6ad8fSAl Viro } 2825dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 2826dae6ad8fSAl Viro 2827dae6ad8fSAl Viro struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, int is_dir) 2828dae6ad8fSAl Viro { 2829dae6ad8fSAl Viro char *tmp = getname(pathname); 2830dae6ad8fSAl Viro struct dentry *res; 2831dae6ad8fSAl Viro if (IS_ERR(tmp)) 2832dae6ad8fSAl Viro return ERR_CAST(tmp); 2833dae6ad8fSAl Viro res = kern_path_create(dfd, tmp, path, is_dir); 2834dae6ad8fSAl Viro putname(tmp); 2835dae6ad8fSAl Viro return res; 2836dae6ad8fSAl Viro } 2837dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 2838dae6ad8fSAl Viro 28391a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 28401da177e4SLinus Torvalds { 2841a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28421da177e4SLinus Torvalds 28431da177e4SLinus Torvalds if (error) 28441da177e4SLinus Torvalds return error; 28451da177e4SLinus Torvalds 2846975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 28471da177e4SLinus Torvalds return -EPERM; 28481da177e4SLinus Torvalds 2849acfa4380SAl Viro if (!dir->i_op->mknod) 28501da177e4SLinus Torvalds return -EPERM; 28511da177e4SLinus Torvalds 285208ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 285308ce5f16SSerge E. Hallyn if (error) 285408ce5f16SSerge E. Hallyn return error; 285508ce5f16SSerge E. Hallyn 28561da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 28571da177e4SLinus Torvalds if (error) 28581da177e4SLinus Torvalds return error; 28591da177e4SLinus Torvalds 28601da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 2861a74574aaSStephen Smalley if (!error) 2862f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28631da177e4SLinus Torvalds return error; 28641da177e4SLinus Torvalds } 28651da177e4SLinus Torvalds 2866f69aac00SAl Viro static int may_mknod(umode_t mode) 2867463c3197SDave Hansen { 2868463c3197SDave Hansen switch (mode & S_IFMT) { 2869463c3197SDave Hansen case S_IFREG: 2870463c3197SDave Hansen case S_IFCHR: 2871463c3197SDave Hansen case S_IFBLK: 2872463c3197SDave Hansen case S_IFIFO: 2873463c3197SDave Hansen case S_IFSOCK: 2874463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 2875463c3197SDave Hansen return 0; 2876463c3197SDave Hansen case S_IFDIR: 2877463c3197SDave Hansen return -EPERM; 2878463c3197SDave Hansen default: 2879463c3197SDave Hansen return -EINVAL; 2880463c3197SDave Hansen } 2881463c3197SDave Hansen } 2882463c3197SDave Hansen 28838208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 28842e4d0924SHeiko Carstens unsigned, dev) 28851da177e4SLinus Torvalds { 28861da177e4SLinus Torvalds struct dentry *dentry; 2887dae6ad8fSAl Viro struct path path; 2888dae6ad8fSAl Viro int error; 28891da177e4SLinus Torvalds 28901da177e4SLinus Torvalds if (S_ISDIR(mode)) 28911da177e4SLinus Torvalds return -EPERM; 28921da177e4SLinus Torvalds 2893dae6ad8fSAl Viro dentry = user_path_create(dfd, filename, &path, 0); 2894dae6ad8fSAl Viro if (IS_ERR(dentry)) 2895dae6ad8fSAl Viro return PTR_ERR(dentry); 28962ad94ae6SAl Viro 2897dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 2898ce3b0f8dSAl Viro mode &= ~current_umask(); 2899463c3197SDave Hansen error = may_mknod(mode); 2900463c3197SDave Hansen if (error) 2901463c3197SDave Hansen goto out_dput; 2902dae6ad8fSAl Viro error = mnt_want_write(path.mnt); 2903463c3197SDave Hansen if (error) 2904463c3197SDave Hansen goto out_dput; 2905dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 2906be6d3e56SKentaro Takeda if (error) 2907be6d3e56SKentaro Takeda goto out_drop_write; 29081da177e4SLinus Torvalds switch (mode & S_IFMT) { 29091da177e4SLinus Torvalds case 0: case S_IFREG: 2910dae6ad8fSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,NULL); 29111da177e4SLinus Torvalds break; 29121da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 2913dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 29141da177e4SLinus Torvalds new_decode_dev(dev)); 29151da177e4SLinus Torvalds break; 29161da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 2917dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 29181da177e4SLinus Torvalds break; 29191da177e4SLinus Torvalds } 2920be6d3e56SKentaro Takeda out_drop_write: 2921dae6ad8fSAl Viro mnt_drop_write(path.mnt); 2922463c3197SDave Hansen out_dput: 29231da177e4SLinus Torvalds dput(dentry); 2924dae6ad8fSAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 2925dae6ad8fSAl Viro path_put(&path); 29261da177e4SLinus Torvalds 29271da177e4SLinus Torvalds return error; 29281da177e4SLinus Torvalds } 29291da177e4SLinus Torvalds 29308208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 29315590ff0dSUlrich Drepper { 29325590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 29335590ff0dSUlrich Drepper } 29345590ff0dSUlrich Drepper 293518bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 29361da177e4SLinus Torvalds { 2937a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 29388de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 29391da177e4SLinus Torvalds 29401da177e4SLinus Torvalds if (error) 29411da177e4SLinus Torvalds return error; 29421da177e4SLinus Torvalds 2943acfa4380SAl Viro if (!dir->i_op->mkdir) 29441da177e4SLinus Torvalds return -EPERM; 29451da177e4SLinus Torvalds 29461da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 29471da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 29481da177e4SLinus Torvalds if (error) 29491da177e4SLinus Torvalds return error; 29501da177e4SLinus Torvalds 29518de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 29528de52778SAl Viro return -EMLINK; 29538de52778SAl Viro 29541da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2955a74574aaSStephen Smalley if (!error) 2956f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 29571da177e4SLinus Torvalds return error; 29581da177e4SLinus Torvalds } 29591da177e4SLinus Torvalds 2960a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 29611da177e4SLinus Torvalds { 29626902d925SDave Hansen struct dentry *dentry; 2963dae6ad8fSAl Viro struct path path; 2964dae6ad8fSAl Viro int error; 29651da177e4SLinus Torvalds 2966dae6ad8fSAl Viro dentry = user_path_create(dfd, pathname, &path, 1); 29676902d925SDave Hansen if (IS_ERR(dentry)) 2968dae6ad8fSAl Viro return PTR_ERR(dentry); 29696902d925SDave Hansen 2970dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 2971ce3b0f8dSAl Viro mode &= ~current_umask(); 2972dae6ad8fSAl Viro error = mnt_want_write(path.mnt); 2973463c3197SDave Hansen if (error) 2974463c3197SDave Hansen goto out_dput; 2975dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 2976be6d3e56SKentaro Takeda if (error) 2977be6d3e56SKentaro Takeda goto out_drop_write; 2978dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 2979be6d3e56SKentaro Takeda out_drop_write: 2980dae6ad8fSAl Viro mnt_drop_write(path.mnt); 2981463c3197SDave Hansen out_dput: 29821da177e4SLinus Torvalds dput(dentry); 2983dae6ad8fSAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 2984dae6ad8fSAl Viro path_put(&path); 29851da177e4SLinus Torvalds return error; 29861da177e4SLinus Torvalds } 29871da177e4SLinus Torvalds 2988a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 29895590ff0dSUlrich Drepper { 29905590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 29915590ff0dSUlrich Drepper } 29925590ff0dSUlrich Drepper 29931da177e4SLinus Torvalds /* 2994a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 2995c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 2996a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 2997a71905f0SSage Weil * then we drop the dentry now. 29981da177e4SLinus Torvalds * 29991da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 30001da177e4SLinus Torvalds * do a 30011da177e4SLinus Torvalds * 30021da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 30031da177e4SLinus Torvalds * return -EBUSY; 30041da177e4SLinus Torvalds * 30051da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 30061da177e4SLinus Torvalds * that is still in use by something else.. 30071da177e4SLinus Torvalds */ 30081da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 30091da177e4SLinus Torvalds { 30101da177e4SLinus Torvalds shrink_dcache_parent(dentry); 30111da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 301264252c75SSage Weil if (dentry->d_count == 1) 30131da177e4SLinus Torvalds __d_drop(dentry); 30141da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 30151da177e4SLinus Torvalds } 30161da177e4SLinus Torvalds 30171da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 30181da177e4SLinus Torvalds { 30191da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 30201da177e4SLinus Torvalds 30211da177e4SLinus Torvalds if (error) 30221da177e4SLinus Torvalds return error; 30231da177e4SLinus Torvalds 3024acfa4380SAl Viro if (!dir->i_op->rmdir) 30251da177e4SLinus Torvalds return -EPERM; 30261da177e4SLinus Torvalds 30271d2ef590SAl Viro dget(dentry); 30281b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3029912dbc15SSage Weil 30301da177e4SLinus Torvalds error = -EBUSY; 3031912dbc15SSage Weil if (d_mountpoint(dentry)) 3032912dbc15SSage Weil goto out; 3033912dbc15SSage Weil 30341da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3035912dbc15SSage Weil if (error) 3036912dbc15SSage Weil goto out; 3037912dbc15SSage Weil 30383cebde24SSage Weil shrink_dcache_parent(dentry); 30391da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3040912dbc15SSage Weil if (error) 3041912dbc15SSage Weil goto out; 3042912dbc15SSage Weil 30431da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3044d83c49f3SAl Viro dont_mount(dentry); 30451da177e4SLinus Torvalds 3046912dbc15SSage Weil out: 3047912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 30481d2ef590SAl Viro dput(dentry); 3049912dbc15SSage Weil if (!error) 3050912dbc15SSage Weil d_delete(dentry); 30511da177e4SLinus Torvalds return error; 30521da177e4SLinus Torvalds } 30531da177e4SLinus Torvalds 30545590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 30551da177e4SLinus Torvalds { 30561da177e4SLinus Torvalds int error = 0; 30571da177e4SLinus Torvalds char * name; 30581da177e4SLinus Torvalds struct dentry *dentry; 30591da177e4SLinus Torvalds struct nameidata nd; 30601da177e4SLinus Torvalds 30612ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 30621da177e4SLinus Torvalds if (error) 30632ad94ae6SAl Viro return error; 30641da177e4SLinus Torvalds 30651da177e4SLinus Torvalds switch(nd.last_type) { 30661da177e4SLinus Torvalds case LAST_DOTDOT: 30671da177e4SLinus Torvalds error = -ENOTEMPTY; 30681da177e4SLinus Torvalds goto exit1; 30691da177e4SLinus Torvalds case LAST_DOT: 30701da177e4SLinus Torvalds error = -EINVAL; 30711da177e4SLinus Torvalds goto exit1; 30721da177e4SLinus Torvalds case LAST_ROOT: 30731da177e4SLinus Torvalds error = -EBUSY; 30741da177e4SLinus Torvalds goto exit1; 30751da177e4SLinus Torvalds } 30760612d9fbSOGAWA Hirofumi 30770612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 30780612d9fbSOGAWA Hirofumi 30794ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 308049705b77SChristoph Hellwig dentry = lookup_hash(&nd); 30811da177e4SLinus Torvalds error = PTR_ERR(dentry); 30826902d925SDave Hansen if (IS_ERR(dentry)) 30836902d925SDave Hansen goto exit2; 3084e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3085e6bc45d6STheodore Ts'o error = -ENOENT; 3086e6bc45d6STheodore Ts'o goto exit3; 3087e6bc45d6STheodore Ts'o } 30880622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 30890622753bSDave Hansen if (error) 30900622753bSDave Hansen goto exit3; 3091be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 3092be6d3e56SKentaro Takeda if (error) 3093be6d3e56SKentaro Takeda goto exit4; 30944ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 3095be6d3e56SKentaro Takeda exit4: 30960622753bSDave Hansen mnt_drop_write(nd.path.mnt); 30970622753bSDave Hansen exit3: 30981da177e4SLinus Torvalds dput(dentry); 30996902d925SDave Hansen exit2: 31004ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 31011da177e4SLinus Torvalds exit1: 31021d957f9bSJan Blunck path_put(&nd.path); 31031da177e4SLinus Torvalds putname(name); 31041da177e4SLinus Torvalds return error; 31051da177e4SLinus Torvalds } 31061da177e4SLinus Torvalds 31073cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 31085590ff0dSUlrich Drepper { 31095590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 31105590ff0dSUlrich Drepper } 31115590ff0dSUlrich Drepper 31121da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 31131da177e4SLinus Torvalds { 31141da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 31151da177e4SLinus Torvalds 31161da177e4SLinus Torvalds if (error) 31171da177e4SLinus Torvalds return error; 31181da177e4SLinus Torvalds 3119acfa4380SAl Viro if (!dir->i_op->unlink) 31201da177e4SLinus Torvalds return -EPERM; 31211da177e4SLinus Torvalds 31221b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 31231da177e4SLinus Torvalds if (d_mountpoint(dentry)) 31241da177e4SLinus Torvalds error = -EBUSY; 31251da177e4SLinus Torvalds else { 31261da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3127bec1052eSAl Viro if (!error) { 31281da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 3129bec1052eSAl Viro if (!error) 3130d83c49f3SAl Viro dont_mount(dentry); 3131bec1052eSAl Viro } 31321da177e4SLinus Torvalds } 31331b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 31341da177e4SLinus Torvalds 31351da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 31361da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 3137ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 31381da177e4SLinus Torvalds d_delete(dentry); 31391da177e4SLinus Torvalds } 31400eeca283SRobert Love 31411da177e4SLinus Torvalds return error; 31421da177e4SLinus Torvalds } 31431da177e4SLinus Torvalds 31441da177e4SLinus Torvalds /* 31451da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 31461b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 31471da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 31481da177e4SLinus Torvalds * while waiting on the I/O. 31491da177e4SLinus Torvalds */ 31505590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 31511da177e4SLinus Torvalds { 31522ad94ae6SAl Viro int error; 31531da177e4SLinus Torvalds char *name; 31541da177e4SLinus Torvalds struct dentry *dentry; 31551da177e4SLinus Torvalds struct nameidata nd; 31561da177e4SLinus Torvalds struct inode *inode = NULL; 31571da177e4SLinus Torvalds 31582ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 31591da177e4SLinus Torvalds if (error) 31602ad94ae6SAl Viro return error; 31612ad94ae6SAl Viro 31621da177e4SLinus Torvalds error = -EISDIR; 31631da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 31641da177e4SLinus Torvalds goto exit1; 31650612d9fbSOGAWA Hirofumi 31660612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 31670612d9fbSOGAWA Hirofumi 31684ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 316949705b77SChristoph Hellwig dentry = lookup_hash(&nd); 31701da177e4SLinus Torvalds error = PTR_ERR(dentry); 31711da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 31721da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 317350338b88STörök Edwin if (nd.last.name[nd.last.len]) 317450338b88STörök Edwin goto slashes; 31751da177e4SLinus Torvalds inode = dentry->d_inode; 317650338b88STörök Edwin if (!inode) 3177e6bc45d6STheodore Ts'o goto slashes; 31787de9c6eeSAl Viro ihold(inode); 31790622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 31800622753bSDave Hansen if (error) 31810622753bSDave Hansen goto exit2; 3182be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 3183be6d3e56SKentaro Takeda if (error) 3184be6d3e56SKentaro Takeda goto exit3; 31854ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 3186be6d3e56SKentaro Takeda exit3: 31870622753bSDave Hansen mnt_drop_write(nd.path.mnt); 31881da177e4SLinus Torvalds exit2: 31891da177e4SLinus Torvalds dput(dentry); 31901da177e4SLinus Torvalds } 31914ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 31921da177e4SLinus Torvalds if (inode) 31931da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 31941da177e4SLinus Torvalds exit1: 31951d957f9bSJan Blunck path_put(&nd.path); 31961da177e4SLinus Torvalds putname(name); 31971da177e4SLinus Torvalds return error; 31981da177e4SLinus Torvalds 31991da177e4SLinus Torvalds slashes: 32001da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 32011da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 32021da177e4SLinus Torvalds goto exit2; 32031da177e4SLinus Torvalds } 32041da177e4SLinus Torvalds 32052e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 32065590ff0dSUlrich Drepper { 32075590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 32085590ff0dSUlrich Drepper return -EINVAL; 32095590ff0dSUlrich Drepper 32105590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 32115590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 32125590ff0dSUlrich Drepper 32135590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 32145590ff0dSUlrich Drepper } 32155590ff0dSUlrich Drepper 32163480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 32175590ff0dSUlrich Drepper { 32185590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 32195590ff0dSUlrich Drepper } 32205590ff0dSUlrich Drepper 3221db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 32221da177e4SLinus Torvalds { 3223a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 32241da177e4SLinus Torvalds 32251da177e4SLinus Torvalds if (error) 32261da177e4SLinus Torvalds return error; 32271da177e4SLinus Torvalds 3228acfa4380SAl Viro if (!dir->i_op->symlink) 32291da177e4SLinus Torvalds return -EPERM; 32301da177e4SLinus Torvalds 32311da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 32321da177e4SLinus Torvalds if (error) 32331da177e4SLinus Torvalds return error; 32341da177e4SLinus Torvalds 32351da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3236a74574aaSStephen Smalley if (!error) 3237f38aa942SAmy Griffis fsnotify_create(dir, dentry); 32381da177e4SLinus Torvalds return error; 32391da177e4SLinus Torvalds } 32401da177e4SLinus Torvalds 32412e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 32422e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 32431da177e4SLinus Torvalds { 32442ad94ae6SAl Viro int error; 32451da177e4SLinus Torvalds char *from; 32466902d925SDave Hansen struct dentry *dentry; 3247dae6ad8fSAl Viro struct path path; 32481da177e4SLinus Torvalds 32491da177e4SLinus Torvalds from = getname(oldname); 32501da177e4SLinus Torvalds if (IS_ERR(from)) 32511da177e4SLinus Torvalds return PTR_ERR(from); 32522ad94ae6SAl Viro 3253dae6ad8fSAl Viro dentry = user_path_create(newdfd, newname, &path, 0); 32541da177e4SLinus Torvalds error = PTR_ERR(dentry); 32556902d925SDave Hansen if (IS_ERR(dentry)) 3256dae6ad8fSAl Viro goto out_putname; 32576902d925SDave Hansen 3258dae6ad8fSAl Viro error = mnt_want_write(path.mnt); 325975c3f29dSDave Hansen if (error) 326075c3f29dSDave Hansen goto out_dput; 3261dae6ad8fSAl Viro error = security_path_symlink(&path, dentry, from); 3262be6d3e56SKentaro Takeda if (error) 3263be6d3e56SKentaro Takeda goto out_drop_write; 3264dae6ad8fSAl Viro error = vfs_symlink(path.dentry->d_inode, dentry, from); 3265be6d3e56SKentaro Takeda out_drop_write: 3266dae6ad8fSAl Viro mnt_drop_write(path.mnt); 326775c3f29dSDave Hansen out_dput: 32681da177e4SLinus Torvalds dput(dentry); 3269dae6ad8fSAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 3270dae6ad8fSAl Viro path_put(&path); 32716902d925SDave Hansen out_putname: 32721da177e4SLinus Torvalds putname(from); 32731da177e4SLinus Torvalds return error; 32741da177e4SLinus Torvalds } 32751da177e4SLinus Torvalds 32763480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 32775590ff0dSUlrich Drepper { 32785590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 32795590ff0dSUlrich Drepper } 32805590ff0dSUlrich Drepper 32811da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 32821da177e4SLinus Torvalds { 32831da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 32848de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 32851da177e4SLinus Torvalds int error; 32861da177e4SLinus Torvalds 32871da177e4SLinus Torvalds if (!inode) 32881da177e4SLinus Torvalds return -ENOENT; 32891da177e4SLinus Torvalds 3290a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 32911da177e4SLinus Torvalds if (error) 32921da177e4SLinus Torvalds return error; 32931da177e4SLinus Torvalds 32941da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 32951da177e4SLinus Torvalds return -EXDEV; 32961da177e4SLinus Torvalds 32971da177e4SLinus Torvalds /* 32981da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 32991da177e4SLinus Torvalds */ 33001da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 33011da177e4SLinus Torvalds return -EPERM; 3302acfa4380SAl Viro if (!dir->i_op->link) 33031da177e4SLinus Torvalds return -EPERM; 33047e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 33051da177e4SLinus Torvalds return -EPERM; 33061da177e4SLinus Torvalds 33071da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 33081da177e4SLinus Torvalds if (error) 33091da177e4SLinus Torvalds return error; 33101da177e4SLinus Torvalds 33117e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 3312aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 3313aae8a97dSAneesh Kumar K.V if (inode->i_nlink == 0) 3314aae8a97dSAneesh Kumar K.V error = -ENOENT; 33158de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 33168de52778SAl Viro error = -EMLINK; 3317aae8a97dSAneesh Kumar K.V else 33181da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 33197e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 3320e31e14ecSStephen Smalley if (!error) 33217e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 33221da177e4SLinus Torvalds return error; 33231da177e4SLinus Torvalds } 33241da177e4SLinus Torvalds 33251da177e4SLinus Torvalds /* 33261da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 33271da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 33281da177e4SLinus Torvalds * newname. --KAB 33291da177e4SLinus Torvalds * 33301da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 33311da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 33321da177e4SLinus Torvalds * and other special files. --ADM 33331da177e4SLinus Torvalds */ 33342e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 33352e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 33361da177e4SLinus Torvalds { 33371da177e4SLinus Torvalds struct dentry *new_dentry; 3338dae6ad8fSAl Viro struct path old_path, new_path; 333911a7b371SAneesh Kumar K.V int how = 0; 33401da177e4SLinus Torvalds int error; 33411da177e4SLinus Torvalds 334211a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 3343c04030e1SUlrich Drepper return -EINVAL; 334411a7b371SAneesh Kumar K.V /* 334511a7b371SAneesh Kumar K.V * To use null names we require CAP_DAC_READ_SEARCH 334611a7b371SAneesh Kumar K.V * This ensures that not everyone will be able to create 334711a7b371SAneesh Kumar K.V * handlink using the passed filedescriptor. 334811a7b371SAneesh Kumar K.V */ 334911a7b371SAneesh Kumar K.V if (flags & AT_EMPTY_PATH) { 335011a7b371SAneesh Kumar K.V if (!capable(CAP_DAC_READ_SEARCH)) 335111a7b371SAneesh Kumar K.V return -ENOENT; 335211a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 335311a7b371SAneesh Kumar K.V } 3354c04030e1SUlrich Drepper 335511a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 335611a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 335711a7b371SAneesh Kumar K.V 335811a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 33591da177e4SLinus Torvalds if (error) 33602ad94ae6SAl Viro return error; 33612ad94ae6SAl Viro 3362dae6ad8fSAl Viro new_dentry = user_path_create(newdfd, newname, &new_path, 0); 33631da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 33646902d925SDave Hansen if (IS_ERR(new_dentry)) 3365dae6ad8fSAl Viro goto out; 3366dae6ad8fSAl Viro 3367dae6ad8fSAl Viro error = -EXDEV; 3368dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 3369dae6ad8fSAl Viro goto out_dput; 3370dae6ad8fSAl Viro error = mnt_want_write(new_path.mnt); 337175c3f29dSDave Hansen if (error) 337275c3f29dSDave Hansen goto out_dput; 3373dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 3374be6d3e56SKentaro Takeda if (error) 3375be6d3e56SKentaro Takeda goto out_drop_write; 3376dae6ad8fSAl Viro error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry); 3377be6d3e56SKentaro Takeda out_drop_write: 3378dae6ad8fSAl Viro mnt_drop_write(new_path.mnt); 337975c3f29dSDave Hansen out_dput: 33801da177e4SLinus Torvalds dput(new_dentry); 3381dae6ad8fSAl Viro mutex_unlock(&new_path.dentry->d_inode->i_mutex); 3382dae6ad8fSAl Viro path_put(&new_path); 33831da177e4SLinus Torvalds out: 33842d8f3038SAl Viro path_put(&old_path); 33851da177e4SLinus Torvalds 33861da177e4SLinus Torvalds return error; 33871da177e4SLinus Torvalds } 33881da177e4SLinus Torvalds 33893480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 33905590ff0dSUlrich Drepper { 3391c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 33925590ff0dSUlrich Drepper } 33935590ff0dSUlrich Drepper 33941da177e4SLinus Torvalds /* 33951da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 33961da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 33971da177e4SLinus Torvalds * Problems: 33981da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 33991da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 34001da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 3401a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 34021da177e4SLinus Torvalds * story. 34031da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 34041b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 34051da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 34061da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 3407a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 34081da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 34091da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 34101da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 3411a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 34121da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 34131da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 34141da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 3415e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 34161b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 34171da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 3418c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 34191da177e4SLinus Torvalds * locking]. 34201da177e4SLinus Torvalds */ 342175c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 34221da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 34231da177e4SLinus Torvalds { 34241da177e4SLinus Torvalds int error = 0; 34259055cba7SSage Weil struct inode *target = new_dentry->d_inode; 34268de52778SAl Viro unsigned max_links = new_dir->i_sb->s_max_links; 34271da177e4SLinus Torvalds 34281da177e4SLinus Torvalds /* 34291da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 34301da177e4SLinus Torvalds * we'll need to flip '..'. 34311da177e4SLinus Torvalds */ 34321da177e4SLinus Torvalds if (new_dir != old_dir) { 3433f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 34341da177e4SLinus Torvalds if (error) 34351da177e4SLinus Torvalds return error; 34361da177e4SLinus Torvalds } 34371da177e4SLinus Torvalds 34381da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 34391da177e4SLinus Torvalds if (error) 34401da177e4SLinus Torvalds return error; 34411da177e4SLinus Torvalds 34421d2ef590SAl Viro dget(new_dentry); 3443d83c49f3SAl Viro if (target) 34441b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 34459055cba7SSage Weil 34461da177e4SLinus Torvalds error = -EBUSY; 34479055cba7SSage Weil if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) 34489055cba7SSage Weil goto out; 34499055cba7SSage Weil 34508de52778SAl Viro error = -EMLINK; 34518de52778SAl Viro if (max_links && !target && new_dir != old_dir && 34528de52778SAl Viro new_dir->i_nlink >= max_links) 34538de52778SAl Viro goto out; 34548de52778SAl Viro 34553cebde24SSage Weil if (target) 34563cebde24SSage Weil shrink_dcache_parent(new_dentry); 34571da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 34589055cba7SSage Weil if (error) 34599055cba7SSage Weil goto out; 34609055cba7SSage Weil 34611da177e4SLinus Torvalds if (target) { 34621da177e4SLinus Torvalds target->i_flags |= S_DEAD; 3463d83c49f3SAl Viro dont_mount(new_dentry); 3464d83c49f3SAl Viro } 34659055cba7SSage Weil out: 34669055cba7SSage Weil if (target) 34671b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 34681d2ef590SAl Viro dput(new_dentry); 3469e31e14ecSStephen Smalley if (!error) 3470349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 34711da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 34721da177e4SLinus Torvalds return error; 34731da177e4SLinus Torvalds } 34741da177e4SLinus Torvalds 347575c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 34761da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 34771da177e4SLinus Torvalds { 347851892bbbSSage Weil struct inode *target = new_dentry->d_inode; 34791da177e4SLinus Torvalds int error; 34801da177e4SLinus Torvalds 34811da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 34821da177e4SLinus Torvalds if (error) 34831da177e4SLinus Torvalds return error; 34841da177e4SLinus Torvalds 34851da177e4SLinus Torvalds dget(new_dentry); 34861da177e4SLinus Torvalds if (target) 34871b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 348851892bbbSSage Weil 34891da177e4SLinus Torvalds error = -EBUSY; 349051892bbbSSage Weil if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 349151892bbbSSage Weil goto out; 349251892bbbSSage Weil 34931da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 349451892bbbSSage Weil if (error) 349551892bbbSSage Weil goto out; 349651892bbbSSage Weil 3497bec1052eSAl Viro if (target) 3498d83c49f3SAl Viro dont_mount(new_dentry); 3499349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 35001da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 350151892bbbSSage Weil out: 35021da177e4SLinus Torvalds if (target) 35031b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 35041da177e4SLinus Torvalds dput(new_dentry); 35051da177e4SLinus Torvalds return error; 35061da177e4SLinus Torvalds } 35071da177e4SLinus Torvalds 35081da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 35091da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 35101da177e4SLinus Torvalds { 35111da177e4SLinus Torvalds int error; 35121da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 351359b0df21SEric Paris const unsigned char *old_name; 35141da177e4SLinus Torvalds 35151da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 35161da177e4SLinus Torvalds return 0; 35171da177e4SLinus Torvalds 35181da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 35191da177e4SLinus Torvalds if (error) 35201da177e4SLinus Torvalds return error; 35211da177e4SLinus Torvalds 35221da177e4SLinus Torvalds if (!new_dentry->d_inode) 3523a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 35241da177e4SLinus Torvalds else 35251da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 35261da177e4SLinus Torvalds if (error) 35271da177e4SLinus Torvalds return error; 35281da177e4SLinus Torvalds 3529acfa4380SAl Viro if (!old_dir->i_op->rename) 35301da177e4SLinus Torvalds return -EPERM; 35311da177e4SLinus Torvalds 35320eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 35330eeca283SRobert Love 35341da177e4SLinus Torvalds if (is_dir) 35351da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 35361da177e4SLinus Torvalds else 35371da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 3538123df294SAl Viro if (!error) 3539123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 35405a190ae6SAl Viro new_dentry->d_inode, old_dentry); 35410eeca283SRobert Love fsnotify_oldname_free(old_name); 35420eeca283SRobert Love 35431da177e4SLinus Torvalds return error; 35441da177e4SLinus Torvalds } 35451da177e4SLinus Torvalds 35462e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 35472e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 35481da177e4SLinus Torvalds { 35491da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 35501da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 35511da177e4SLinus Torvalds struct dentry *trap; 35521da177e4SLinus Torvalds struct nameidata oldnd, newnd; 35532ad94ae6SAl Viro char *from; 35542ad94ae6SAl Viro char *to; 35552ad94ae6SAl Viro int error; 35561da177e4SLinus Torvalds 35572ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 35581da177e4SLinus Torvalds if (error) 35591da177e4SLinus Torvalds goto exit; 35601da177e4SLinus Torvalds 35612ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 35621da177e4SLinus Torvalds if (error) 35631da177e4SLinus Torvalds goto exit1; 35641da177e4SLinus Torvalds 35651da177e4SLinus Torvalds error = -EXDEV; 35664ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 35671da177e4SLinus Torvalds goto exit2; 35681da177e4SLinus Torvalds 35694ac91378SJan Blunck old_dir = oldnd.path.dentry; 35701da177e4SLinus Torvalds error = -EBUSY; 35711da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 35721da177e4SLinus Torvalds goto exit2; 35731da177e4SLinus Torvalds 35744ac91378SJan Blunck new_dir = newnd.path.dentry; 35751da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 35761da177e4SLinus Torvalds goto exit2; 35771da177e4SLinus Torvalds 35780612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 35790612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 35804e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 35810612d9fbSOGAWA Hirofumi 35821da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 35831da177e4SLinus Torvalds 358449705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 35851da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 35861da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 35871da177e4SLinus Torvalds goto exit3; 35881da177e4SLinus Torvalds /* source must exist */ 35891da177e4SLinus Torvalds error = -ENOENT; 35901da177e4SLinus Torvalds if (!old_dentry->d_inode) 35911da177e4SLinus Torvalds goto exit4; 35921da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 35931da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 35941da177e4SLinus Torvalds error = -ENOTDIR; 35951da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 35961da177e4SLinus Torvalds goto exit4; 35971da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 35981da177e4SLinus Torvalds goto exit4; 35991da177e4SLinus Torvalds } 36001da177e4SLinus Torvalds /* source should not be ancestor of target */ 36011da177e4SLinus Torvalds error = -EINVAL; 36021da177e4SLinus Torvalds if (old_dentry == trap) 36031da177e4SLinus Torvalds goto exit4; 360449705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 36051da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 36061da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 36071da177e4SLinus Torvalds goto exit4; 36081da177e4SLinus Torvalds /* target should not be an ancestor of source */ 36091da177e4SLinus Torvalds error = -ENOTEMPTY; 36101da177e4SLinus Torvalds if (new_dentry == trap) 36111da177e4SLinus Torvalds goto exit5; 36121da177e4SLinus Torvalds 36139079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 36149079b1ebSDave Hansen if (error) 36159079b1ebSDave Hansen goto exit5; 3616be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 3617be6d3e56SKentaro Takeda &newnd.path, new_dentry); 3618be6d3e56SKentaro Takeda if (error) 3619be6d3e56SKentaro Takeda goto exit6; 36201da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 36211da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 3622be6d3e56SKentaro Takeda exit6: 36239079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 36241da177e4SLinus Torvalds exit5: 36251da177e4SLinus Torvalds dput(new_dentry); 36261da177e4SLinus Torvalds exit4: 36271da177e4SLinus Torvalds dput(old_dentry); 36281da177e4SLinus Torvalds exit3: 36291da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 36301da177e4SLinus Torvalds exit2: 36311d957f9bSJan Blunck path_put(&newnd.path); 36322ad94ae6SAl Viro putname(to); 36331da177e4SLinus Torvalds exit1: 36341d957f9bSJan Blunck path_put(&oldnd.path); 36351da177e4SLinus Torvalds putname(from); 36362ad94ae6SAl Viro exit: 36371da177e4SLinus Torvalds return error; 36381da177e4SLinus Torvalds } 36391da177e4SLinus Torvalds 3640a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 36415590ff0dSUlrich Drepper { 36425590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 36435590ff0dSUlrich Drepper } 36445590ff0dSUlrich Drepper 36451da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 36461da177e4SLinus Torvalds { 36471da177e4SLinus Torvalds int len; 36481da177e4SLinus Torvalds 36491da177e4SLinus Torvalds len = PTR_ERR(link); 36501da177e4SLinus Torvalds if (IS_ERR(link)) 36511da177e4SLinus Torvalds goto out; 36521da177e4SLinus Torvalds 36531da177e4SLinus Torvalds len = strlen(link); 36541da177e4SLinus Torvalds if (len > (unsigned) buflen) 36551da177e4SLinus Torvalds len = buflen; 36561da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 36571da177e4SLinus Torvalds len = -EFAULT; 36581da177e4SLinus Torvalds out: 36591da177e4SLinus Torvalds return len; 36601da177e4SLinus Torvalds } 36611da177e4SLinus Torvalds 36621da177e4SLinus Torvalds /* 36631da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 36641da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 36651da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 36661da177e4SLinus Torvalds */ 36671da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 36681da177e4SLinus Torvalds { 36691da177e4SLinus Torvalds struct nameidata nd; 3670cc314eefSLinus Torvalds void *cookie; 3671694a1764SMarcin Slusarz int res; 3672cc314eefSLinus Torvalds 36731da177e4SLinus Torvalds nd.depth = 0; 3674cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 3675694a1764SMarcin Slusarz if (IS_ERR(cookie)) 3676694a1764SMarcin Slusarz return PTR_ERR(cookie); 3677694a1764SMarcin Slusarz 3678694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 36791da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 3680cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 3681694a1764SMarcin Slusarz return res; 36821da177e4SLinus Torvalds } 36831da177e4SLinus Torvalds 36841da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 36851da177e4SLinus Torvalds { 36861da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 36871da177e4SLinus Torvalds } 36881da177e4SLinus Torvalds 36891da177e4SLinus Torvalds /* get the link contents into pagecache */ 36901da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 36911da177e4SLinus Torvalds { 3692ebd09abbSDuane Griffin char *kaddr; 36931da177e4SLinus Torvalds struct page *page; 36941da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 3695090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 36961da177e4SLinus Torvalds if (IS_ERR(page)) 36976fe6900eSNick Piggin return (char*)page; 36981da177e4SLinus Torvalds *ppage = page; 3699ebd09abbSDuane Griffin kaddr = kmap(page); 3700ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 3701ebd09abbSDuane Griffin return kaddr; 37021da177e4SLinus Torvalds } 37031da177e4SLinus Torvalds 37041da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 37051da177e4SLinus Torvalds { 37061da177e4SLinus Torvalds struct page *page = NULL; 37071da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 37081da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 37091da177e4SLinus Torvalds if (page) { 37101da177e4SLinus Torvalds kunmap(page); 37111da177e4SLinus Torvalds page_cache_release(page); 37121da177e4SLinus Torvalds } 37131da177e4SLinus Torvalds return res; 37141da177e4SLinus Torvalds } 37151da177e4SLinus Torvalds 3716cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 37171da177e4SLinus Torvalds { 3718cc314eefSLinus Torvalds struct page *page = NULL; 37191da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 3720cc314eefSLinus Torvalds return page; 37211da177e4SLinus Torvalds } 37221da177e4SLinus Torvalds 3723cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 37241da177e4SLinus Torvalds { 3725cc314eefSLinus Torvalds struct page *page = cookie; 3726cc314eefSLinus Torvalds 3727cc314eefSLinus Torvalds if (page) { 37281da177e4SLinus Torvalds kunmap(page); 37291da177e4SLinus Torvalds page_cache_release(page); 37301da177e4SLinus Torvalds } 37311da177e4SLinus Torvalds } 37321da177e4SLinus Torvalds 373354566b2cSNick Piggin /* 373454566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 373554566b2cSNick Piggin */ 373654566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 37371da177e4SLinus Torvalds { 37381da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 37390adb25d2SKirill Korotaev struct page *page; 3740afddba49SNick Piggin void *fsdata; 3741beb497abSDmitriy Monakhov int err; 37421da177e4SLinus Torvalds char *kaddr; 374354566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 374454566b2cSNick Piggin if (nofs) 374554566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 37461da177e4SLinus Torvalds 37477e53cac4SNeilBrown retry: 3748afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 374954566b2cSNick Piggin flags, &page, &fsdata); 37501da177e4SLinus Torvalds if (err) 3751afddba49SNick Piggin goto fail; 3752afddba49SNick Piggin 3753e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 37541da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 3755e8e3c3d6SCong Wang kunmap_atomic(kaddr); 3756afddba49SNick Piggin 3757afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 3758afddba49SNick Piggin page, fsdata); 37591da177e4SLinus Torvalds if (err < 0) 37601da177e4SLinus Torvalds goto fail; 3761afddba49SNick Piggin if (err < len-1) 3762afddba49SNick Piggin goto retry; 3763afddba49SNick Piggin 37641da177e4SLinus Torvalds mark_inode_dirty(inode); 37651da177e4SLinus Torvalds return 0; 37661da177e4SLinus Torvalds fail: 37671da177e4SLinus Torvalds return err; 37681da177e4SLinus Torvalds } 37691da177e4SLinus Torvalds 37700adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 37710adb25d2SKirill Korotaev { 37720adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 377354566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 37740adb25d2SKirill Korotaev } 37750adb25d2SKirill Korotaev 377692e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 37771da177e4SLinus Torvalds .readlink = generic_readlink, 37781da177e4SLinus Torvalds .follow_link = page_follow_link_light, 37791da177e4SLinus Torvalds .put_link = page_put_link, 37801da177e4SLinus Torvalds }; 37811da177e4SLinus Torvalds 37822d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 3783cc53ce53SDavid Howells EXPORT_SYMBOL(follow_down_one); 37841da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 37851da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 37861da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 37871da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 37881da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 37891da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 37901da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 37911da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 37921da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 37930adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 37941da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 37951da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 3796d1811465SAl Viro EXPORT_SYMBOL(kern_path); 379716f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 3798f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 37991da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 38001da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 38011da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 38021da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 38031da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 38041da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 38051da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 38061da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 38071da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 38081da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 38091da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 38101da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 38111da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 38121da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 3813