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 /** 3180bdaea90SDavid Howells * __inode_permission - Check for access rights to a given inode 3190bdaea90SDavid Howells * @inode: Inode to check permission on 3200bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 321cb23beb5SChristoph Hellwig * 3220bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. 323948409c7SAndreas Gruenbacher * 324948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 3250bdaea90SDavid Howells * 3260bdaea90SDavid Howells * This does not check for a read-only file system. You probably want 3270bdaea90SDavid Howells * inode_permission(). 328cb23beb5SChristoph Hellwig */ 3290bdaea90SDavid Howells int __inode_permission(struct inode *inode, int mask) 3301da177e4SLinus Torvalds { 331e6305c43SAl Viro int retval; 3321da177e4SLinus Torvalds 3333ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 3341da177e4SLinus Torvalds /* 3351da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 3361da177e4SLinus Torvalds */ 3371da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 3381da177e4SLinus Torvalds return -EACCES; 3391da177e4SLinus Torvalds } 3401da177e4SLinus Torvalds 3413ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 3421da177e4SLinus Torvalds if (retval) 3431da177e4SLinus Torvalds return retval; 3441da177e4SLinus Torvalds 34508ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 34608ce5f16SSerge E. Hallyn if (retval) 34708ce5f16SSerge E. Hallyn return retval; 34808ce5f16SSerge E. Hallyn 349d09ca739SEric Paris return security_inode_permission(inode, mask); 3501da177e4SLinus Torvalds } 3511da177e4SLinus Torvalds 352f4d6ff89SAl Viro /** 3530bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 3540bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 3550bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 3560bdaea90SDavid Howells * 3570bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 3580bdaea90SDavid Howells */ 3590bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 3600bdaea90SDavid Howells { 3610bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 3620bdaea90SDavid Howells umode_t mode = inode->i_mode; 3630bdaea90SDavid Howells 3640bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 3650bdaea90SDavid Howells if ((sb->s_flags & MS_RDONLY) && 3660bdaea90SDavid Howells (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 3670bdaea90SDavid Howells return -EROFS; 3680bdaea90SDavid Howells } 3690bdaea90SDavid Howells return 0; 3700bdaea90SDavid Howells } 3710bdaea90SDavid Howells 3720bdaea90SDavid Howells /** 3730bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 3740bdaea90SDavid Howells * @inode: Inode to check permission on 3750bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 3760bdaea90SDavid Howells * 3770bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 3780bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 3790bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 3800bdaea90SDavid Howells * 3810bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 3820bdaea90SDavid Howells */ 3830bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 3840bdaea90SDavid Howells { 3850bdaea90SDavid Howells int retval; 3860bdaea90SDavid Howells 3870bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 3880bdaea90SDavid Howells if (retval) 3890bdaea90SDavid Howells return retval; 3900bdaea90SDavid Howells return __inode_permission(inode, mask); 3910bdaea90SDavid Howells } 3920bdaea90SDavid Howells 3930bdaea90SDavid Howells /** 3945dd784d0SJan Blunck * path_get - get a reference to a path 3955dd784d0SJan Blunck * @path: path to get the reference to 3965dd784d0SJan Blunck * 3975dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 3985dd784d0SJan Blunck */ 3995dd784d0SJan Blunck void path_get(struct path *path) 4005dd784d0SJan Blunck { 4015dd784d0SJan Blunck mntget(path->mnt); 4025dd784d0SJan Blunck dget(path->dentry); 4035dd784d0SJan Blunck } 4045dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4055dd784d0SJan Blunck 4065dd784d0SJan Blunck /** 4071d957f9bSJan Blunck * path_put - put a reference to a path 4081d957f9bSJan Blunck * @path: path to put the reference to 4091d957f9bSJan Blunck * 4101d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4111d957f9bSJan Blunck */ 4121d957f9bSJan Blunck void path_put(struct path *path) 4131da177e4SLinus Torvalds { 4141d957f9bSJan Blunck dput(path->dentry); 4151d957f9bSJan Blunck mntput(path->mnt); 4161da177e4SLinus Torvalds } 4171d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4181da177e4SLinus Torvalds 41919660af7SAl Viro /* 42031e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 42119660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 42219660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 42319660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 42419660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 42519660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 42619660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 42719660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 42831e6b01fSNick Piggin */ 42931e6b01fSNick Piggin 43032a7991bSAl Viro static inline void lock_rcu_walk(void) 43132a7991bSAl Viro { 43232a7991bSAl Viro br_read_lock(&vfsmount_lock); 43332a7991bSAl Viro rcu_read_lock(); 43432a7991bSAl Viro } 43532a7991bSAl Viro 43632a7991bSAl Viro static inline void unlock_rcu_walk(void) 43732a7991bSAl Viro { 43832a7991bSAl Viro rcu_read_unlock(); 43932a7991bSAl Viro br_read_unlock(&vfsmount_lock); 44032a7991bSAl Viro } 44132a7991bSAl Viro 44231e6b01fSNick Piggin /** 44319660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 44419660af7SAl Viro * @nd: nameidata pathwalk data 44519660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 44639191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 44731e6b01fSNick Piggin * 44819660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 44919660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 45019660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 45131e6b01fSNick Piggin */ 45219660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 45331e6b01fSNick Piggin { 45431e6b01fSNick Piggin struct fs_struct *fs = current->fs; 45531e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 4565b6ca027SAl Viro int want_root = 0; 45731e6b01fSNick Piggin 45831e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 4595b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 4605b6ca027SAl Viro want_root = 1; 46131e6b01fSNick Piggin spin_lock(&fs->lock); 46231e6b01fSNick Piggin if (nd->root.mnt != fs->root.mnt || 46331e6b01fSNick Piggin nd->root.dentry != fs->root.dentry) 46431e6b01fSNick Piggin goto err_root; 46531e6b01fSNick Piggin } 46631e6b01fSNick Piggin spin_lock(&parent->d_lock); 46719660af7SAl Viro if (!dentry) { 46819660af7SAl Viro if (!__d_rcu_to_refcount(parent, nd->seq)) 46919660af7SAl Viro goto err_parent; 47019660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 47119660af7SAl Viro } else { 47294c0d4ecSAl Viro if (dentry->d_parent != parent) 47394c0d4ecSAl Viro goto err_parent; 47431e6b01fSNick Piggin spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); 47531e6b01fSNick Piggin if (!__d_rcu_to_refcount(dentry, nd->seq)) 47619660af7SAl Viro goto err_child; 47731e6b01fSNick Piggin /* 47819660af7SAl Viro * If the sequence check on the child dentry passed, then 47919660af7SAl Viro * the child has not been removed from its parent. This 48019660af7SAl Viro * means the parent dentry must be valid and able to take 48119660af7SAl Viro * a reference at this point. 48231e6b01fSNick Piggin */ 48331e6b01fSNick Piggin BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent); 48431e6b01fSNick Piggin BUG_ON(!parent->d_count); 48531e6b01fSNick Piggin parent->d_count++; 48631e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 48719660af7SAl Viro } 48831e6b01fSNick Piggin spin_unlock(&parent->d_lock); 4895b6ca027SAl Viro if (want_root) { 49031e6b01fSNick Piggin path_get(&nd->root); 49131e6b01fSNick Piggin spin_unlock(&fs->lock); 49231e6b01fSNick Piggin } 49331e6b01fSNick Piggin mntget(nd->path.mnt); 49431e6b01fSNick Piggin 49532a7991bSAl Viro unlock_rcu_walk(); 49631e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 49731e6b01fSNick Piggin return 0; 49819660af7SAl Viro 49919660af7SAl Viro err_child: 50031e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 50119660af7SAl Viro err_parent: 50231e6b01fSNick Piggin spin_unlock(&parent->d_lock); 50331e6b01fSNick Piggin err_root: 5045b6ca027SAl Viro if (want_root) 50531e6b01fSNick Piggin spin_unlock(&fs->lock); 50631e6b01fSNick Piggin return -ECHILD; 50731e6b01fSNick Piggin } 50831e6b01fSNick Piggin 5094ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 51034286d66SNick Piggin { 5114ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 51234286d66SNick Piggin } 51334286d66SNick Piggin 5149f1fafeeSAl Viro /** 5159f1fafeeSAl Viro * complete_walk - successful completion of path walk 5169f1fafeeSAl Viro * @nd: pointer nameidata 51739159de2SJeff Layton * 5189f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 5199f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 5209f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 5219f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 5229f1fafeeSAl Viro * need to drop nd->path. 52339159de2SJeff Layton */ 5249f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 52539159de2SJeff Layton { 52616c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 52739159de2SJeff Layton int status; 52839159de2SJeff Layton 5299f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 5309f1fafeeSAl Viro nd->flags &= ~LOOKUP_RCU; 5319f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 5329f1fafeeSAl Viro nd->root.mnt = NULL; 5339f1fafeeSAl Viro spin_lock(&dentry->d_lock); 5349f1fafeeSAl Viro if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) { 5359f1fafeeSAl Viro spin_unlock(&dentry->d_lock); 53632a7991bSAl Viro unlock_rcu_walk(); 5379f1fafeeSAl Viro return -ECHILD; 5389f1fafeeSAl Viro } 5399f1fafeeSAl Viro BUG_ON(nd->inode != dentry->d_inode); 5409f1fafeeSAl Viro spin_unlock(&dentry->d_lock); 5419f1fafeeSAl Viro mntget(nd->path.mnt); 54232a7991bSAl Viro unlock_rcu_walk(); 5439f1fafeeSAl Viro } 5449f1fafeeSAl Viro 54516c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 54639159de2SJeff Layton return 0; 54739159de2SJeff Layton 54816c2cd71SAl Viro if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE))) 54916c2cd71SAl Viro return 0; 55016c2cd71SAl Viro 55116c2cd71SAl Viro if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))) 55216c2cd71SAl Viro return 0; 55316c2cd71SAl Viro 55416c2cd71SAl Viro /* Note: we do not d_invalidate() */ 5554ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 55639159de2SJeff Layton if (status > 0) 55739159de2SJeff Layton return 0; 55839159de2SJeff Layton 55916c2cd71SAl Viro if (!status) 56039159de2SJeff Layton status = -ESTALE; 56116c2cd71SAl Viro 5629f1fafeeSAl Viro path_put(&nd->path); 56339159de2SJeff Layton return status; 56439159de2SJeff Layton } 56539159de2SJeff Layton 5662a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 5672a737871SAl Viro { 568f7ad3c6bSMiklos Szeredi if (!nd->root.mnt) 569f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 5702a737871SAl Viro } 5712a737871SAl Viro 5726de88d72SAl Viro static int link_path_walk(const char *, struct nameidata *); 5736de88d72SAl Viro 57431e6b01fSNick Piggin static __always_inline void set_root_rcu(struct nameidata *nd) 57531e6b01fSNick Piggin { 57631e6b01fSNick Piggin if (!nd->root.mnt) { 57731e6b01fSNick Piggin struct fs_struct *fs = current->fs; 578c28cc364SNick Piggin unsigned seq; 579c28cc364SNick Piggin 580c28cc364SNick Piggin do { 581c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 58231e6b01fSNick Piggin nd->root = fs->root; 583c1530019STim Chen nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 584c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 58531e6b01fSNick Piggin } 58631e6b01fSNick Piggin } 58731e6b01fSNick Piggin 588f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 5891da177e4SLinus Torvalds { 59031e6b01fSNick Piggin int ret; 59131e6b01fSNick Piggin 5921da177e4SLinus Torvalds if (IS_ERR(link)) 5931da177e4SLinus Torvalds goto fail; 5941da177e4SLinus Torvalds 5951da177e4SLinus Torvalds if (*link == '/') { 5962a737871SAl Viro set_root(nd); 5971d957f9bSJan Blunck path_put(&nd->path); 5982a737871SAl Viro nd->path = nd->root; 5992a737871SAl Viro path_get(&nd->root); 60016c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 6011da177e4SLinus Torvalds } 60231e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 603b4091d5fSChristoph Hellwig 60431e6b01fSNick Piggin ret = link_path_walk(link, nd); 60531e6b01fSNick Piggin return ret; 6061da177e4SLinus Torvalds fail: 6071d957f9bSJan Blunck path_put(&nd->path); 6081da177e4SLinus Torvalds return PTR_ERR(link); 6091da177e4SLinus Torvalds } 6101da177e4SLinus Torvalds 6111d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 612051d3812SIan Kent { 613051d3812SIan Kent dput(path->dentry); 6144ac91378SJan Blunck if (path->mnt != nd->path.mnt) 615051d3812SIan Kent mntput(path->mnt); 616051d3812SIan Kent } 617051d3812SIan Kent 6187b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 6197b9337aaSNick Piggin struct nameidata *nd) 620051d3812SIan Kent { 62131e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 6224ac91378SJan Blunck dput(nd->path.dentry); 62331e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 6244ac91378SJan Blunck mntput(nd->path.mnt); 6259a229683SHuang Shijie } 62631e6b01fSNick Piggin nd->path.mnt = path->mnt; 6274ac91378SJan Blunck nd->path.dentry = path->dentry; 628051d3812SIan Kent } 629051d3812SIan Kent 630b5fb63c1SChristoph Hellwig /* 631b5fb63c1SChristoph Hellwig * Helper to directly jump to a known parsed path from ->follow_link, 632b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 633b5fb63c1SChristoph Hellwig */ 634b5fb63c1SChristoph Hellwig void nd_jump_link(struct nameidata *nd, struct path *path) 635b5fb63c1SChristoph Hellwig { 636b5fb63c1SChristoph Hellwig path_put(&nd->path); 637b5fb63c1SChristoph Hellwig 638b5fb63c1SChristoph Hellwig nd->path = *path; 639b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 640b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 641b5fb63c1SChristoph Hellwig 642b5fb63c1SChristoph Hellwig BUG_ON(nd->inode->i_op->follow_link); 643b5fb63c1SChristoph Hellwig } 644b5fb63c1SChristoph Hellwig 645574197e0SAl Viro static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) 646574197e0SAl Viro { 647574197e0SAl Viro struct inode *inode = link->dentry->d_inode; 6486d7b5aaeSAl Viro if (inode->i_op->put_link) 649574197e0SAl Viro inode->i_op->put_link(link->dentry, nd, cookie); 650574197e0SAl Viro path_put(link); 651574197e0SAl Viro } 652574197e0SAl Viro 653800179c9SKees Cook int sysctl_protected_symlinks __read_mostly = 1; 654800179c9SKees Cook int sysctl_protected_hardlinks __read_mostly = 1; 655800179c9SKees Cook 656800179c9SKees Cook /** 657800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 658800179c9SKees Cook * @link: The path of the symlink 659800179c9SKees Cook * 660800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 661800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 662800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 663800179c9SKees Cook * processes from failing races against path names that may change out 664800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 665800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 666800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 667800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 668800179c9SKees Cook * 669800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 670800179c9SKees Cook */ 671800179c9SKees Cook static inline int may_follow_link(struct path *link, struct nameidata *nd) 672800179c9SKees Cook { 673800179c9SKees Cook const struct inode *inode; 674800179c9SKees Cook const struct inode *parent; 675800179c9SKees Cook 676800179c9SKees Cook if (!sysctl_protected_symlinks) 677800179c9SKees Cook return 0; 678800179c9SKees Cook 679800179c9SKees Cook /* Allowed if owner and follower match. */ 680800179c9SKees Cook inode = link->dentry->d_inode; 681800179c9SKees Cook if (current_cred()->fsuid == inode->i_uid) 682800179c9SKees Cook return 0; 683800179c9SKees Cook 684800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 685800179c9SKees Cook parent = nd->path.dentry->d_inode; 686800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 687800179c9SKees Cook return 0; 688800179c9SKees Cook 689800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 690800179c9SKees Cook if (parent->i_uid == inode->i_uid) 691800179c9SKees Cook return 0; 692800179c9SKees Cook 693800179c9SKees Cook path_put_conditional(link, nd); 694800179c9SKees Cook path_put(&nd->path); 695800179c9SKees Cook return -EACCES; 696800179c9SKees Cook } 697800179c9SKees Cook 698800179c9SKees Cook /** 699800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 700800179c9SKees Cook * @inode: the source inode to hardlink from 701800179c9SKees Cook * 702800179c9SKees Cook * Return false if at least one of the following conditions: 703800179c9SKees Cook * - inode is not a regular file 704800179c9SKees Cook * - inode is setuid 705800179c9SKees Cook * - inode is setgid and group-exec 706800179c9SKees Cook * - access failure for read and write 707800179c9SKees Cook * 708800179c9SKees Cook * Otherwise returns true. 709800179c9SKees Cook */ 710800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 711800179c9SKees Cook { 712800179c9SKees Cook umode_t mode = inode->i_mode; 713800179c9SKees Cook 714800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 715800179c9SKees Cook if (!S_ISREG(mode)) 716800179c9SKees Cook return false; 717800179c9SKees Cook 718800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 719800179c9SKees Cook if (mode & S_ISUID) 720800179c9SKees Cook return false; 721800179c9SKees Cook 722800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 723800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 724800179c9SKees Cook return false; 725800179c9SKees Cook 726800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 727800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 728800179c9SKees Cook return false; 729800179c9SKees Cook 730800179c9SKees Cook return true; 731800179c9SKees Cook } 732800179c9SKees Cook 733800179c9SKees Cook /** 734800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 735800179c9SKees Cook * @link: the source to hardlink from 736800179c9SKees Cook * 737800179c9SKees Cook * Block hardlink when all of: 738800179c9SKees Cook * - sysctl_protected_hardlinks enabled 739800179c9SKees Cook * - fsuid does not match inode 740800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 741800179c9SKees Cook * - not CAP_FOWNER 742800179c9SKees Cook * 743800179c9SKees Cook * Returns 0 if successful, -ve on error. 744800179c9SKees Cook */ 745800179c9SKees Cook static int may_linkat(struct path *link) 746800179c9SKees Cook { 747800179c9SKees Cook const struct cred *cred; 748800179c9SKees Cook struct inode *inode; 749800179c9SKees Cook 750800179c9SKees Cook if (!sysctl_protected_hardlinks) 751800179c9SKees Cook return 0; 752800179c9SKees Cook 753800179c9SKees Cook cred = current_cred(); 754800179c9SKees Cook inode = link->dentry->d_inode; 755800179c9SKees Cook 756800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 757800179c9SKees Cook * otherwise, it must be a safe source. 758800179c9SKees Cook */ 759800179c9SKees Cook if (cred->fsuid == inode->i_uid || safe_hardlink_source(inode) || 760800179c9SKees Cook capable(CAP_FOWNER)) 761800179c9SKees Cook return 0; 762800179c9SKees Cook 763800179c9SKees Cook return -EPERM; 764800179c9SKees Cook } 765800179c9SKees Cook 766def4af30SAl Viro static __always_inline int 767574197e0SAl Viro follow_link(struct path *link, struct nameidata *nd, void **p) 7681da177e4SLinus Torvalds { 7697b9337aaSNick Piggin struct dentry *dentry = link->dentry; 7706d7b5aaeSAl Viro int error; 7716d7b5aaeSAl Viro char *s; 7721da177e4SLinus Torvalds 773844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 774844a3917SAl Viro 7750e794589SAl Viro if (link->mnt == nd->path.mnt) 7760e794589SAl Viro mntget(link->mnt); 7770e794589SAl Viro 7786d7b5aaeSAl Viro error = -ELOOP; 7796d7b5aaeSAl Viro if (unlikely(current->total_link_count >= 40)) 7806d7b5aaeSAl Viro goto out_put_nd_path; 7816d7b5aaeSAl Viro 782574197e0SAl Viro cond_resched(); 783574197e0SAl Viro current->total_link_count++; 784574197e0SAl Viro 78568ac1234SAl Viro touch_atime(link); 7861da177e4SLinus Torvalds nd_set_link(nd, NULL); 787cd4e91d3SAl Viro 78836f3b4f6SAl Viro error = security_inode_follow_link(link->dentry, nd); 7896d7b5aaeSAl Viro if (error) 7906d7b5aaeSAl Viro goto out_put_nd_path; 79136f3b4f6SAl Viro 79286acdca1SAl Viro nd->last_type = LAST_BIND; 793def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 794def4af30SAl Viro error = PTR_ERR(*p); 7956d7b5aaeSAl Viro if (IS_ERR(*p)) 796408ef013SChristoph Hellwig goto out_put_nd_path; 7976d7b5aaeSAl Viro 798cc314eefSLinus Torvalds error = 0; 7996d7b5aaeSAl Viro s = nd_get_link(nd); 8006d7b5aaeSAl Viro if (s) { 8011da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 8026d7b5aaeSAl Viro if (unlikely(error)) 8036d7b5aaeSAl Viro put_link(nd, link, *p); 804b5fb63c1SChristoph Hellwig } 8056d7b5aaeSAl Viro 8066d7b5aaeSAl Viro return error; 8076d7b5aaeSAl Viro 8086d7b5aaeSAl Viro out_put_nd_path: 8096d7b5aaeSAl Viro path_put(&nd->path); 8106d7b5aaeSAl Viro path_put(link); 8111da177e4SLinus Torvalds return error; 8121da177e4SLinus Torvalds } 8131da177e4SLinus Torvalds 81431e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 81531e6b01fSNick Piggin { 8160714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 8170714a533SAl Viro struct mount *parent; 81831e6b01fSNick Piggin struct dentry *mountpoint; 81931e6b01fSNick Piggin 8200714a533SAl Viro parent = mnt->mnt_parent; 8210714a533SAl Viro if (&parent->mnt == path->mnt) 82231e6b01fSNick Piggin return 0; 823a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 82431e6b01fSNick Piggin path->dentry = mountpoint; 8250714a533SAl Viro path->mnt = &parent->mnt; 82631e6b01fSNick Piggin return 1; 82731e6b01fSNick Piggin } 82831e6b01fSNick Piggin 829f015f126SDavid Howells /* 830f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 831f015f126SDavid Howells * 832f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 833f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 834f015f126SDavid Howells * Up is towards /. 835f015f126SDavid Howells * 836f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 837f015f126SDavid Howells * root. 838f015f126SDavid Howells */ 839bab77ebfSAl Viro int follow_up(struct path *path) 8401da177e4SLinus Torvalds { 8410714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 8420714a533SAl Viro struct mount *parent; 8431da177e4SLinus Torvalds struct dentry *mountpoint; 84499b7db7bSNick Piggin 845962830dfSAndi Kleen br_read_lock(&vfsmount_lock); 8460714a533SAl Viro parent = mnt->mnt_parent; 8473c0a6163SAl Viro if (parent == mnt) { 848962830dfSAndi Kleen br_read_unlock(&vfsmount_lock); 8491da177e4SLinus Torvalds return 0; 8501da177e4SLinus Torvalds } 8510714a533SAl Viro mntget(&parent->mnt); 852a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 853962830dfSAndi Kleen br_read_unlock(&vfsmount_lock); 854bab77ebfSAl Viro dput(path->dentry); 855bab77ebfSAl Viro path->dentry = mountpoint; 856bab77ebfSAl Viro mntput(path->mnt); 8570714a533SAl Viro path->mnt = &parent->mnt; 8581da177e4SLinus Torvalds return 1; 8591da177e4SLinus Torvalds } 8601da177e4SLinus Torvalds 861b5c84bf6SNick Piggin /* 8629875cf80SDavid Howells * Perform an automount 8639875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 8649875cf80SDavid Howells * were called with. 8651da177e4SLinus Torvalds */ 8669875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 8679875cf80SDavid Howells bool *need_mntput) 86831e6b01fSNick Piggin { 8699875cf80SDavid Howells struct vfsmount *mnt; 870ea5b778aSDavid Howells int err; 8719875cf80SDavid Howells 8729875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 8739875cf80SDavid Howells return -EREMOTE; 8749875cf80SDavid Howells 8750ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 8760ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 8770ec26fd0SMiklos Szeredi * the name. 8780ec26fd0SMiklos Szeredi * 8790ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 8805a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 8810ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 8820ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 8830ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 8840ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 8855a30d8a2SDavid Howells */ 8865a30d8a2SDavid Howells if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 887d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 8885a30d8a2SDavid Howells path->dentry->d_inode) 8899875cf80SDavid Howells return -EISDIR; 8900ec26fd0SMiklos Szeredi 8919875cf80SDavid Howells current->total_link_count++; 8929875cf80SDavid Howells if (current->total_link_count >= 40) 8939875cf80SDavid Howells return -ELOOP; 8949875cf80SDavid Howells 8959875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 8969875cf80SDavid Howells if (IS_ERR(mnt)) { 8979875cf80SDavid Howells /* 8989875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 8999875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 9009875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 9019875cf80SDavid Howells * 9029875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 9039875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 9049875cf80SDavid Howells * the path is inaccessible and we should say so. 9059875cf80SDavid Howells */ 90649084c3bSAl Viro if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) 9079875cf80SDavid Howells return -EREMOTE; 9089875cf80SDavid Howells return PTR_ERR(mnt); 90931e6b01fSNick Piggin } 910ea5b778aSDavid Howells 9119875cf80SDavid Howells if (!mnt) /* mount collision */ 9129875cf80SDavid Howells return 0; 9139875cf80SDavid Howells 9148aef1884SAl Viro if (!*need_mntput) { 9158aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 9168aef1884SAl Viro mntget(path->mnt); 9178aef1884SAl Viro *need_mntput = true; 9188aef1884SAl Viro } 91919a167afSAl Viro err = finish_automount(mnt, path); 920ea5b778aSDavid Howells 921ea5b778aSDavid Howells switch (err) { 922ea5b778aSDavid Howells case -EBUSY: 923ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 92419a167afSAl Viro return 0; 925ea5b778aSDavid Howells case 0: 9268aef1884SAl Viro path_put(path); 9279875cf80SDavid Howells path->mnt = mnt; 9289875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 9299875cf80SDavid Howells return 0; 93019a167afSAl Viro default: 93119a167afSAl Viro return err; 9329875cf80SDavid Howells } 93319a167afSAl Viro 934ea5b778aSDavid Howells } 9359875cf80SDavid Howells 9369875cf80SDavid Howells /* 9379875cf80SDavid Howells * Handle a dentry that is managed in some way. 938cc53ce53SDavid Howells * - Flagged for transit management (autofs) 9399875cf80SDavid Howells * - Flagged as mountpoint 9409875cf80SDavid Howells * - Flagged as automount point 9419875cf80SDavid Howells * 9429875cf80SDavid Howells * This may only be called in refwalk mode. 9439875cf80SDavid Howells * 9449875cf80SDavid Howells * Serialization is taken care of in namespace.c 9459875cf80SDavid Howells */ 9469875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 9479875cf80SDavid Howells { 9488aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 9499875cf80SDavid Howells unsigned managed; 9509875cf80SDavid Howells bool need_mntput = false; 9518aef1884SAl Viro int ret = 0; 9529875cf80SDavid Howells 9539875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 9549875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 9559875cf80SDavid Howells * the components of that value change under us */ 9569875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 9579875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 9589875cf80SDavid Howells unlikely(managed != 0)) { 959cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 960cc53ce53SDavid Howells * being held. */ 961cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 962cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 963cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 9641aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 965cc53ce53SDavid Howells if (ret < 0) 9668aef1884SAl Viro break; 967cc53ce53SDavid Howells } 968cc53ce53SDavid Howells 9699875cf80SDavid Howells /* Transit to a mounted filesystem. */ 9709875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 9719875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 9729875cf80SDavid Howells if (mounted) { 9739875cf80SDavid Howells dput(path->dentry); 9749875cf80SDavid Howells if (need_mntput) 975463ffb2eSAl Viro mntput(path->mnt); 976463ffb2eSAl Viro path->mnt = mounted; 977463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 9789875cf80SDavid Howells need_mntput = true; 9799875cf80SDavid Howells continue; 980463ffb2eSAl Viro } 981463ffb2eSAl Viro 9829875cf80SDavid Howells /* Something is mounted on this dentry in another 9839875cf80SDavid Howells * namespace and/or whatever was mounted there in this 9849875cf80SDavid Howells * namespace got unmounted before we managed to get the 9859875cf80SDavid Howells * vfsmount_lock */ 9861da177e4SLinus Torvalds } 9879875cf80SDavid Howells 9889875cf80SDavid Howells /* Handle an automount point */ 9899875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 9909875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 9919875cf80SDavid Howells if (ret < 0) 9928aef1884SAl Viro break; 9939875cf80SDavid Howells continue; 9949875cf80SDavid Howells } 9959875cf80SDavid Howells 9969875cf80SDavid Howells /* We didn't change the current path point */ 9979875cf80SDavid Howells break; 9989875cf80SDavid Howells } 9998aef1884SAl Viro 10008aef1884SAl Viro if (need_mntput && path->mnt == mnt) 10018aef1884SAl Viro mntput(path->mnt); 10028aef1884SAl Viro if (ret == -EISDIR) 10038aef1884SAl Viro ret = 0; 1004a3fbbde7SAl Viro return ret < 0 ? ret : need_mntput; 10051da177e4SLinus Torvalds } 10061da177e4SLinus Torvalds 1007cc53ce53SDavid Howells int follow_down_one(struct path *path) 10081da177e4SLinus Torvalds { 10091da177e4SLinus Torvalds struct vfsmount *mounted; 10101da177e4SLinus Torvalds 10111c755af4SAl Viro mounted = lookup_mnt(path); 10121da177e4SLinus Torvalds if (mounted) { 10139393bd07SAl Viro dput(path->dentry); 10149393bd07SAl Viro mntput(path->mnt); 10159393bd07SAl Viro path->mnt = mounted; 10169393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 10171da177e4SLinus Torvalds return 1; 10181da177e4SLinus Torvalds } 10191da177e4SLinus Torvalds return 0; 10201da177e4SLinus Torvalds } 10211da177e4SLinus Torvalds 102262a7375eSIan Kent static inline bool managed_dentry_might_block(struct dentry *dentry) 102362a7375eSIan Kent { 102462a7375eSIan Kent return (dentry->d_flags & DCACHE_MANAGE_TRANSIT && 102562a7375eSIan Kent dentry->d_op->d_manage(dentry, true) < 0); 102662a7375eSIan Kent } 102762a7375eSIan Kent 10289875cf80SDavid Howells /* 1029287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1030287548e4SAl Viro * we meet a managed dentry that would need blocking. 10319875cf80SDavid Howells */ 10329875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1033287548e4SAl Viro struct inode **inode) 10349875cf80SDavid Howells { 103562a7375eSIan Kent for (;;) { 1036c7105365SAl Viro struct mount *mounted; 103762a7375eSIan Kent /* 103862a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 103962a7375eSIan Kent * that wants to block transit. 104062a7375eSIan Kent */ 1041287548e4SAl Viro if (unlikely(managed_dentry_might_block(path->dentry))) 1042ab90911fSDavid Howells return false; 104362a7375eSIan Kent 104462a7375eSIan Kent if (!d_mountpoint(path->dentry)) 104562a7375eSIan Kent break; 104662a7375eSIan Kent 10479875cf80SDavid Howells mounted = __lookup_mnt(path->mnt, path->dentry, 1); 10489875cf80SDavid Howells if (!mounted) 10499875cf80SDavid Howells break; 1050c7105365SAl Viro path->mnt = &mounted->mnt; 1051c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1052a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 10539875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 105459430262SLinus Torvalds /* 105559430262SLinus Torvalds * Update the inode too. We don't need to re-check the 105659430262SLinus Torvalds * dentry sequence number here after this d_inode read, 105759430262SLinus Torvalds * because a mount-point is always pinned. 105859430262SLinus Torvalds */ 105959430262SLinus Torvalds *inode = path->dentry->d_inode; 10609875cf80SDavid Howells } 10619875cf80SDavid Howells return true; 10629875cf80SDavid Howells } 10639875cf80SDavid Howells 1064dea39376SAl Viro static void follow_mount_rcu(struct nameidata *nd) 1065287548e4SAl Viro { 1066dea39376SAl Viro while (d_mountpoint(nd->path.dentry)) { 1067c7105365SAl Viro struct mount *mounted; 1068dea39376SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1); 1069287548e4SAl Viro if (!mounted) 1070287548e4SAl Viro break; 1071c7105365SAl Viro nd->path.mnt = &mounted->mnt; 1072c7105365SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 1073dea39376SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1074287548e4SAl Viro } 1075287548e4SAl Viro } 1076287548e4SAl Viro 107731e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 107831e6b01fSNick Piggin { 107931e6b01fSNick Piggin set_root_rcu(nd); 108031e6b01fSNick Piggin 108131e6b01fSNick Piggin while (1) { 108231e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 108331e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 108431e6b01fSNick Piggin break; 108531e6b01fSNick Piggin } 108631e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 108731e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 108831e6b01fSNick Piggin struct dentry *parent = old->d_parent; 108931e6b01fSNick Piggin unsigned seq; 109031e6b01fSNick Piggin 109131e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 109231e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1093ef7562d5SAl Viro goto failed; 109431e6b01fSNick Piggin nd->path.dentry = parent; 109531e6b01fSNick Piggin nd->seq = seq; 109631e6b01fSNick Piggin break; 109731e6b01fSNick Piggin } 109831e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 109931e6b01fSNick Piggin break; 110031e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 110131e6b01fSNick Piggin } 1102dea39376SAl Viro follow_mount_rcu(nd); 1103dea39376SAl Viro nd->inode = nd->path.dentry->d_inode; 110431e6b01fSNick Piggin return 0; 1105ef7562d5SAl Viro 1106ef7562d5SAl Viro failed: 1107ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 11085b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1109ef7562d5SAl Viro nd->root.mnt = NULL; 111032a7991bSAl Viro unlock_rcu_walk(); 1111ef7562d5SAl Viro return -ECHILD; 111231e6b01fSNick Piggin } 111331e6b01fSNick Piggin 11149875cf80SDavid Howells /* 1115cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1116cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1117cc53ce53SDavid Howells * caller is permitted to proceed or not. 1118cc53ce53SDavid Howells */ 11197cc90cc3SAl Viro int follow_down(struct path *path) 1120cc53ce53SDavid Howells { 1121cc53ce53SDavid Howells unsigned managed; 1122cc53ce53SDavid Howells int ret; 1123cc53ce53SDavid Howells 1124cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1125cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1126cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1127cc53ce53SDavid Howells * being held. 1128cc53ce53SDavid Howells * 1129cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1130cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1131cc53ce53SDavid Howells * other than its daemon the right to mount on its 1132cc53ce53SDavid Howells * superstructure. 1133cc53ce53SDavid Howells * 1134cc53ce53SDavid Howells * The filesystem may sleep at this point. 1135cc53ce53SDavid Howells */ 1136cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1137cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1138cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1139ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 11401aed3e42SAl Viro path->dentry, false); 1141cc53ce53SDavid Howells if (ret < 0) 1142cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1143cc53ce53SDavid Howells } 1144cc53ce53SDavid Howells 1145cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1146cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1147cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1148cc53ce53SDavid Howells if (!mounted) 1149cc53ce53SDavid Howells break; 1150cc53ce53SDavid Howells dput(path->dentry); 1151cc53ce53SDavid Howells mntput(path->mnt); 1152cc53ce53SDavid Howells path->mnt = mounted; 1153cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1154cc53ce53SDavid Howells continue; 1155cc53ce53SDavid Howells } 1156cc53ce53SDavid Howells 1157cc53ce53SDavid Howells /* Don't handle automount points here */ 1158cc53ce53SDavid Howells break; 1159cc53ce53SDavid Howells } 1160cc53ce53SDavid Howells return 0; 1161cc53ce53SDavid Howells } 1162cc53ce53SDavid Howells 1163cc53ce53SDavid Howells /* 11649875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 11659875cf80SDavid Howells */ 11669875cf80SDavid Howells static void follow_mount(struct path *path) 11679875cf80SDavid Howells { 11689875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 11699875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 11709875cf80SDavid Howells if (!mounted) 11719875cf80SDavid Howells break; 11729875cf80SDavid Howells dput(path->dentry); 11739875cf80SDavid Howells mntput(path->mnt); 11749875cf80SDavid Howells path->mnt = mounted; 11759875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 11769875cf80SDavid Howells } 11779875cf80SDavid Howells } 11789875cf80SDavid Howells 117931e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 11801da177e4SLinus Torvalds { 11812a737871SAl Viro set_root(nd); 1182e518ddb7SAndreas Mohr 11831da177e4SLinus Torvalds while(1) { 11844ac91378SJan Blunck struct dentry *old = nd->path.dentry; 11851da177e4SLinus Torvalds 11862a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 11872a737871SAl Viro nd->path.mnt == nd->root.mnt) { 11881da177e4SLinus Torvalds break; 11891da177e4SLinus Torvalds } 11904ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 11913088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 11923088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 11931da177e4SLinus Torvalds dput(old); 11941da177e4SLinus Torvalds break; 11951da177e4SLinus Torvalds } 11963088dd70SAl Viro if (!follow_up(&nd->path)) 11971da177e4SLinus Torvalds break; 11981da177e4SLinus Torvalds } 119979ed0226SAl Viro follow_mount(&nd->path); 120031e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 12011da177e4SLinus Torvalds } 12021da177e4SLinus Torvalds 12031da177e4SLinus Torvalds /* 1204bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1205bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1206bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1207bad61189SMiklos Szeredi * 1208bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1209baa03890SNick Piggin */ 1210bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1211201f956eSAl Viro unsigned int flags, bool *need_lookup) 1212baa03890SNick Piggin { 1213baa03890SNick Piggin struct dentry *dentry; 1214bad61189SMiklos Szeredi int error; 1215baa03890SNick Piggin 1216bad61189SMiklos Szeredi *need_lookup = false; 1217bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1218bad61189SMiklos Szeredi if (dentry) { 1219bad61189SMiklos Szeredi if (d_need_lookup(dentry)) { 1220bad61189SMiklos Szeredi *need_lookup = true; 1221bad61189SMiklos Szeredi } else if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1222201f956eSAl Viro error = d_revalidate(dentry, flags); 1223bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1224bad61189SMiklos Szeredi if (error < 0) { 1225bad61189SMiklos Szeredi dput(dentry); 1226bad61189SMiklos Szeredi return ERR_PTR(error); 1227bad61189SMiklos Szeredi } else if (!d_invalidate(dentry)) { 1228bad61189SMiklos Szeredi dput(dentry); 1229bad61189SMiklos Szeredi dentry = NULL; 1230bad61189SMiklos Szeredi } 1231bad61189SMiklos Szeredi } 1232bad61189SMiklos Szeredi } 1233bad61189SMiklos Szeredi } 1234baa03890SNick Piggin 1235bad61189SMiklos Szeredi if (!dentry) { 1236bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1237baa03890SNick Piggin if (unlikely(!dentry)) 1238baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1239baa03890SNick Piggin 1240bad61189SMiklos Szeredi *need_lookup = true; 1241baa03890SNick Piggin } 1242baa03890SNick Piggin return dentry; 1243baa03890SNick Piggin } 1244baa03890SNick Piggin 1245baa03890SNick Piggin /* 1246bad61189SMiklos Szeredi * Call i_op->lookup on the dentry. The dentry must be negative but may be 1247bad61189SMiklos Szeredi * hashed if it was pouplated with DCACHE_NEED_LOOKUP. 1248bad61189SMiklos Szeredi * 1249bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 125044396f4bSJosef Bacik */ 1251bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 125272bd866aSAl Viro unsigned int flags) 125344396f4bSJosef Bacik { 125444396f4bSJosef Bacik struct dentry *old; 125544396f4bSJosef Bacik 125644396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1257bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1258e188dc02SMiklos Szeredi dput(dentry); 125944396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1260e188dc02SMiklos Szeredi } 126144396f4bSJosef Bacik 126272bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 126344396f4bSJosef Bacik if (unlikely(old)) { 126444396f4bSJosef Bacik dput(dentry); 126544396f4bSJosef Bacik dentry = old; 126644396f4bSJosef Bacik } 126744396f4bSJosef Bacik return dentry; 126844396f4bSJosef Bacik } 126944396f4bSJosef Bacik 1270a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 127172bd866aSAl Viro struct dentry *base, unsigned int flags) 1272a3255546SAl Viro { 1273bad61189SMiklos Szeredi bool need_lookup; 1274a3255546SAl Viro struct dentry *dentry; 1275a3255546SAl Viro 127672bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1277bad61189SMiklos Szeredi if (!need_lookup) 1278a3255546SAl Viro return dentry; 1279bad61189SMiklos Szeredi 128072bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1281a3255546SAl Viro } 1282a3255546SAl Viro 128344396f4bSJosef Bacik /* 12841da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 12851da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 12861da177e4SLinus Torvalds * It _is_ time-critical. 12871da177e4SLinus Torvalds */ 1288697f514dSMiklos Szeredi static int lookup_fast(struct nameidata *nd, struct qstr *name, 128931e6b01fSNick Piggin struct path *path, struct inode **inode) 12901da177e4SLinus Torvalds { 12914ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 129231e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 12935a18fff2SAl Viro int need_reval = 1; 12945a18fff2SAl Viro int status = 1; 12959875cf80SDavid Howells int err; 12969875cf80SDavid Howells 12973cac260aSAl Viro /* 1298b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1299b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1300b04f784eSNick Piggin * do the non-racy lookup, below. 1301b04f784eSNick Piggin */ 130231e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 130331e6b01fSNick Piggin unsigned seq; 130412f8ad4bSLinus Torvalds dentry = __d_lookup_rcu(parent, name, &seq, nd->inode); 13055a18fff2SAl Viro if (!dentry) 13065a18fff2SAl Viro goto unlazy; 13075a18fff2SAl Viro 130812f8ad4bSLinus Torvalds /* 130912f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 131012f8ad4bSLinus Torvalds * the dentry name information from lookup. 131112f8ad4bSLinus Torvalds */ 131212f8ad4bSLinus Torvalds *inode = dentry->d_inode; 131312f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 131412f8ad4bSLinus Torvalds return -ECHILD; 131512f8ad4bSLinus Torvalds 131612f8ad4bSLinus Torvalds /* 131712f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 131812f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 131912f8ad4bSLinus Torvalds * 132012f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 132112f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 132212f8ad4bSLinus Torvalds */ 132331e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 132431e6b01fSNick Piggin return -ECHILD; 132531e6b01fSNick Piggin nd->seq = seq; 13265a18fff2SAl Viro 1327fa4ee159SMiklos Szeredi if (unlikely(d_need_lookup(dentry))) 1328fa4ee159SMiklos Szeredi goto unlazy; 132924643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 13304ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 13315a18fff2SAl Viro if (unlikely(status <= 0)) { 13325a18fff2SAl Viro if (status != -ECHILD) 13335a18fff2SAl Viro need_reval = 0; 13345a18fff2SAl Viro goto unlazy; 13355a18fff2SAl Viro } 133624643087SAl Viro } 133731e6b01fSNick Piggin path->mnt = mnt; 133831e6b01fSNick Piggin path->dentry = dentry; 1339d6e9bd25SAl Viro if (unlikely(!__follow_mount_rcu(nd, path, inode))) 1340d6e9bd25SAl Viro goto unlazy; 1341d6e9bd25SAl Viro if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) 1342d6e9bd25SAl Viro goto unlazy; 13439875cf80SDavid Howells return 0; 13445a18fff2SAl Viro unlazy: 134519660af7SAl Viro if (unlazy_walk(nd, dentry)) 13465a18fff2SAl Viro return -ECHILD; 13475a18fff2SAl Viro } else { 134831e6b01fSNick Piggin dentry = __d_lookup(parent, name); 134924643087SAl Viro } 13505a18fff2SAl Viro 135181e6f520SAl Viro if (unlikely(!dentry)) 135281e6f520SAl Viro goto need_lookup; 13535a18fff2SAl Viro 135481e6f520SAl Viro if (unlikely(d_need_lookup(dentry))) { 135581e6f520SAl Viro dput(dentry); 135681e6f520SAl Viro goto need_lookup; 13575a18fff2SAl Viro } 135881e6f520SAl Viro 13595a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 13604ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 13615a18fff2SAl Viro if (unlikely(status <= 0)) { 13625a18fff2SAl Viro if (status < 0) { 13635a18fff2SAl Viro dput(dentry); 13645a18fff2SAl Viro return status; 13655a18fff2SAl Viro } 13665a18fff2SAl Viro if (!d_invalidate(dentry)) { 13675a18fff2SAl Viro dput(dentry); 136881e6f520SAl Viro goto need_lookup; 13695a18fff2SAl Viro } 13705a18fff2SAl Viro } 1371697f514dSMiklos Szeredi 13721da177e4SLinus Torvalds path->mnt = mnt; 13731da177e4SLinus Torvalds path->dentry = dentry; 13749875cf80SDavid Howells err = follow_managed(path, nd->flags); 137589312214SIan Kent if (unlikely(err < 0)) { 137689312214SIan Kent path_put_conditional(path, nd); 13779875cf80SDavid Howells return err; 137889312214SIan Kent } 1379a3fbbde7SAl Viro if (err) 1380a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 138131e6b01fSNick Piggin *inode = path->dentry->d_inode; 13821da177e4SLinus Torvalds return 0; 138381e6f520SAl Viro 138481e6f520SAl Viro need_lookup: 1385697f514dSMiklos Szeredi return 1; 1386697f514dSMiklos Szeredi } 1387697f514dSMiklos Szeredi 1388697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1389697f514dSMiklos Szeredi static int lookup_slow(struct nameidata *nd, struct qstr *name, 1390697f514dSMiklos Szeredi struct path *path) 1391697f514dSMiklos Szeredi { 1392697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1393697f514dSMiklos Szeredi int err; 1394697f514dSMiklos Szeredi 1395697f514dSMiklos Szeredi parent = nd->path.dentry; 139681e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 139781e6f520SAl Viro 139881e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 139972bd866aSAl Viro dentry = __lookup_hash(name, parent, nd->flags); 140081e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 140181e6f520SAl Viro if (IS_ERR(dentry)) 140281e6f520SAl Viro return PTR_ERR(dentry); 1403697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1404697f514dSMiklos Szeredi path->dentry = dentry; 1405697f514dSMiklos Szeredi err = follow_managed(path, nd->flags); 1406697f514dSMiklos Szeredi if (unlikely(err < 0)) { 1407697f514dSMiklos Szeredi path_put_conditional(path, nd); 1408697f514dSMiklos Szeredi return err; 1409697f514dSMiklos Szeredi } 1410697f514dSMiklos Szeredi if (err) 1411697f514dSMiklos Szeredi nd->flags |= LOOKUP_JUMPED; 1412697f514dSMiklos Szeredi return 0; 14131da177e4SLinus Torvalds } 14141da177e4SLinus Torvalds 141552094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 141652094c8aSAl Viro { 141752094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 14184ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 141952094c8aSAl Viro if (err != -ECHILD) 142052094c8aSAl Viro return err; 142119660af7SAl Viro if (unlazy_walk(nd, NULL)) 142252094c8aSAl Viro return -ECHILD; 142352094c8aSAl Viro } 14244ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 142552094c8aSAl Viro } 142652094c8aSAl Viro 14279856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 14289856fa1bSAl Viro { 14299856fa1bSAl Viro if (type == LAST_DOTDOT) { 14309856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 14319856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 14329856fa1bSAl Viro return -ECHILD; 14339856fa1bSAl Viro } else 14349856fa1bSAl Viro follow_dotdot(nd); 14359856fa1bSAl Viro } 14369856fa1bSAl Viro return 0; 14379856fa1bSAl Viro } 14389856fa1bSAl Viro 1439951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1440951361f9SAl Viro { 1441951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1442951361f9SAl Viro path_put(&nd->path); 1443951361f9SAl Viro } else { 1444951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 14455b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1446951361f9SAl Viro nd->root.mnt = NULL; 144732a7991bSAl Viro unlock_rcu_walk(); 1448951361f9SAl Viro } 1449951361f9SAl Viro } 1450951361f9SAl Viro 14513ddcd056SLinus Torvalds /* 14523ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 14533ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 14543ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 14553ddcd056SLinus Torvalds * for the common case. 14563ddcd056SLinus Torvalds */ 14577813b94aSLinus Torvalds static inline int should_follow_link(struct inode *inode, int follow) 14583ddcd056SLinus Torvalds { 14593ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) { 14603ddcd056SLinus Torvalds if (likely(inode->i_op->follow_link)) 14613ddcd056SLinus Torvalds return follow; 14623ddcd056SLinus Torvalds 14633ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 14643ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 14653ddcd056SLinus Torvalds inode->i_opflags |= IOP_NOFOLLOW; 14663ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 14673ddcd056SLinus Torvalds } 14683ddcd056SLinus Torvalds return 0; 14693ddcd056SLinus Torvalds } 14703ddcd056SLinus Torvalds 1471ce57dfc1SAl Viro static inline int walk_component(struct nameidata *nd, struct path *path, 1472ce57dfc1SAl Viro struct qstr *name, int type, int follow) 1473ce57dfc1SAl Viro { 1474ce57dfc1SAl Viro struct inode *inode; 1475ce57dfc1SAl Viro int err; 1476ce57dfc1SAl Viro /* 1477ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1478ce57dfc1SAl Viro * to be able to know about the current root directory and 1479ce57dfc1SAl Viro * parent relationships. 1480ce57dfc1SAl Viro */ 1481ce57dfc1SAl Viro if (unlikely(type != LAST_NORM)) 1482ce57dfc1SAl Viro return handle_dots(nd, type); 1483697f514dSMiklos Szeredi err = lookup_fast(nd, name, path, &inode); 1484ce57dfc1SAl Viro if (unlikely(err)) { 1485697f514dSMiklos Szeredi if (err < 0) 1486697f514dSMiklos Szeredi goto out_err; 1487697f514dSMiklos Szeredi 1488697f514dSMiklos Szeredi err = lookup_slow(nd, name, path); 1489697f514dSMiklos Szeredi if (err < 0) 1490697f514dSMiklos Szeredi goto out_err; 1491697f514dSMiklos Szeredi 1492697f514dSMiklos Szeredi inode = path->dentry->d_inode; 1493ce57dfc1SAl Viro } 1494697f514dSMiklos Szeredi err = -ENOENT; 1495697f514dSMiklos Szeredi if (!inode) 1496697f514dSMiklos Szeredi goto out_path_put; 1497697f514dSMiklos Szeredi 14987813b94aSLinus Torvalds if (should_follow_link(inode, follow)) { 149919660af7SAl Viro if (nd->flags & LOOKUP_RCU) { 150019660af7SAl Viro if (unlikely(unlazy_walk(nd, path->dentry))) { 1501697f514dSMiklos Szeredi err = -ECHILD; 1502697f514dSMiklos Szeredi goto out_err; 150319660af7SAl Viro } 150419660af7SAl Viro } 1505ce57dfc1SAl Viro BUG_ON(inode != path->dentry->d_inode); 1506ce57dfc1SAl Viro return 1; 1507ce57dfc1SAl Viro } 1508ce57dfc1SAl Viro path_to_nameidata(path, nd); 1509ce57dfc1SAl Viro nd->inode = inode; 1510ce57dfc1SAl Viro return 0; 1511697f514dSMiklos Szeredi 1512697f514dSMiklos Szeredi out_path_put: 1513697f514dSMiklos Szeredi path_to_nameidata(path, nd); 1514697f514dSMiklos Szeredi out_err: 1515697f514dSMiklos Szeredi terminate_walk(nd); 1516697f514dSMiklos Szeredi return err; 1517ce57dfc1SAl Viro } 1518ce57dfc1SAl Viro 15191da177e4SLinus Torvalds /* 1520b356379aSAl Viro * This limits recursive symlink follows to 8, while 1521b356379aSAl Viro * limiting consecutive symlinks to 40. 1522b356379aSAl Viro * 1523b356379aSAl Viro * Without that kind of total limit, nasty chains of consecutive 1524b356379aSAl Viro * symlinks can cause almost arbitrarily long lookups. 1525b356379aSAl Viro */ 1526b356379aSAl Viro static inline int nested_symlink(struct path *path, struct nameidata *nd) 1527b356379aSAl Viro { 1528b356379aSAl Viro int res; 1529b356379aSAl Viro 1530b356379aSAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 1531b356379aSAl Viro path_put_conditional(path, nd); 1532b356379aSAl Viro path_put(&nd->path); 1533b356379aSAl Viro return -ELOOP; 1534b356379aSAl Viro } 15351a4022f8SErez Zadok BUG_ON(nd->depth >= MAX_NESTED_LINKS); 1536b356379aSAl Viro 1537b356379aSAl Viro nd->depth++; 1538b356379aSAl Viro current->link_count++; 1539b356379aSAl Viro 1540b356379aSAl Viro do { 1541b356379aSAl Viro struct path link = *path; 1542b356379aSAl Viro void *cookie; 1543574197e0SAl Viro 1544574197e0SAl Viro res = follow_link(&link, nd, &cookie); 15456d7b5aaeSAl Viro if (res) 15466d7b5aaeSAl Viro break; 1547b356379aSAl Viro res = walk_component(nd, path, &nd->last, 1548b356379aSAl Viro nd->last_type, LOOKUP_FOLLOW); 1549574197e0SAl Viro put_link(nd, &link, cookie); 1550b356379aSAl Viro } while (res > 0); 1551b356379aSAl Viro 1552b356379aSAl Viro current->link_count--; 1553b356379aSAl Viro nd->depth--; 1554b356379aSAl Viro return res; 1555b356379aSAl Viro } 1556b356379aSAl Viro 1557b356379aSAl Viro /* 15583ddcd056SLinus Torvalds * We really don't want to look at inode->i_op->lookup 15593ddcd056SLinus Torvalds * when we don't have to. So we keep a cache bit in 15603ddcd056SLinus Torvalds * the inode ->i_opflags field that says "yes, we can 15613ddcd056SLinus Torvalds * do lookup on this inode". 15623ddcd056SLinus Torvalds */ 15633ddcd056SLinus Torvalds static inline int can_lookup(struct inode *inode) 15643ddcd056SLinus Torvalds { 15653ddcd056SLinus Torvalds if (likely(inode->i_opflags & IOP_LOOKUP)) 15663ddcd056SLinus Torvalds return 1; 15673ddcd056SLinus Torvalds if (likely(!inode->i_op->lookup)) 15683ddcd056SLinus Torvalds return 0; 15693ddcd056SLinus Torvalds 15703ddcd056SLinus Torvalds /* We do this once for the lifetime of the inode */ 15713ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 15723ddcd056SLinus Torvalds inode->i_opflags |= IOP_LOOKUP; 15733ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 15743ddcd056SLinus Torvalds return 1; 15753ddcd056SLinus Torvalds } 15763ddcd056SLinus Torvalds 1577bfcfaa77SLinus Torvalds /* 1578bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1579bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1580bfcfaa77SLinus Torvalds * 1581bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1582bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1583bfcfaa77SLinus Torvalds * fast. 1584bfcfaa77SLinus Torvalds * 1585bfcfaa77SLinus Torvalds * - Little-endian machines (so that we can generate the mask 1586bfcfaa77SLinus Torvalds * of low bytes efficiently). Again, we *could* do a byte 1587bfcfaa77SLinus Torvalds * swapping load on big-endian architectures if that is not 1588bfcfaa77SLinus Torvalds * expensive enough to make the optimization worthless. 1589bfcfaa77SLinus Torvalds * 1590bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1591bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1592bfcfaa77SLinus Torvalds * crossing operation. 1593bfcfaa77SLinus Torvalds * 1594bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1595bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1596bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1597bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1598bfcfaa77SLinus Torvalds */ 1599bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1600bfcfaa77SLinus Torvalds 1601f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1602bfcfaa77SLinus Torvalds 1603f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1604bfcfaa77SLinus Torvalds 1605bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1606bfcfaa77SLinus Torvalds { 1607bfcfaa77SLinus Torvalds hash += hash >> (8*sizeof(int)); 1608bfcfaa77SLinus Torvalds return hash; 1609bfcfaa77SLinus Torvalds } 1610bfcfaa77SLinus Torvalds 1611bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1612bfcfaa77SLinus Torvalds 1613bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1614bfcfaa77SLinus Torvalds 1615bfcfaa77SLinus Torvalds #endif 1616bfcfaa77SLinus Torvalds 1617bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1618bfcfaa77SLinus Torvalds { 1619bfcfaa77SLinus Torvalds unsigned long a, mask; 1620bfcfaa77SLinus Torvalds unsigned long hash = 0; 1621bfcfaa77SLinus Torvalds 1622bfcfaa77SLinus Torvalds for (;;) { 1623e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1624bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1625bfcfaa77SLinus Torvalds break; 1626bfcfaa77SLinus Torvalds hash += a; 1627f132c5beSAl Viro hash *= 9; 1628bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1629bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1630bfcfaa77SLinus Torvalds if (!len) 1631bfcfaa77SLinus Torvalds goto done; 1632bfcfaa77SLinus Torvalds } 1633bfcfaa77SLinus Torvalds mask = ~(~0ul << len*8); 1634bfcfaa77SLinus Torvalds hash += mask & a; 1635bfcfaa77SLinus Torvalds done: 1636bfcfaa77SLinus Torvalds return fold_hash(hash); 1637bfcfaa77SLinus Torvalds } 1638bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1639bfcfaa77SLinus Torvalds 1640bfcfaa77SLinus Torvalds /* 1641bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1642bfcfaa77SLinus Torvalds * return the length of the component; 1643bfcfaa77SLinus Torvalds */ 1644bfcfaa77SLinus Torvalds static inline unsigned long hash_name(const char *name, unsigned int *hashp) 1645bfcfaa77SLinus Torvalds { 164636126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 164736126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1648bfcfaa77SLinus Torvalds 1649bfcfaa77SLinus Torvalds hash = a = 0; 1650bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1651bfcfaa77SLinus Torvalds do { 1652bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1653bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1654e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 165536126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 165636126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1657bfcfaa77SLinus Torvalds 165836126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 165936126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 166036126f8fSLinus Torvalds 166136126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 166236126f8fSLinus Torvalds 166336126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 1664bfcfaa77SLinus Torvalds *hashp = fold_hash(hash); 1665bfcfaa77SLinus Torvalds 166636126f8fSLinus Torvalds return len + find_zero(mask); 1667bfcfaa77SLinus Torvalds } 1668bfcfaa77SLinus Torvalds 1669bfcfaa77SLinus Torvalds #else 1670bfcfaa77SLinus Torvalds 16710145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 16720145acc2SLinus Torvalds { 16730145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 16740145acc2SLinus Torvalds while (len--) 16750145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 16760145acc2SLinus Torvalds return end_name_hash(hash); 16770145acc2SLinus Torvalds } 1678ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 16790145acc2SLinus Torvalds 16803ddcd056SLinus Torvalds /* 1681200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1682200e9ef7SLinus Torvalds * one character. 1683200e9ef7SLinus Torvalds */ 1684200e9ef7SLinus Torvalds static inline unsigned long hash_name(const char *name, unsigned int *hashp) 1685200e9ef7SLinus Torvalds { 1686200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1687200e9ef7SLinus Torvalds unsigned long len = 0, c; 1688200e9ef7SLinus Torvalds 1689200e9ef7SLinus Torvalds c = (unsigned char)*name; 1690200e9ef7SLinus Torvalds do { 1691200e9ef7SLinus Torvalds len++; 1692200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1693200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1694200e9ef7SLinus Torvalds } while (c && c != '/'); 1695200e9ef7SLinus Torvalds *hashp = end_name_hash(hash); 1696200e9ef7SLinus Torvalds return len; 1697200e9ef7SLinus Torvalds } 1698200e9ef7SLinus Torvalds 1699bfcfaa77SLinus Torvalds #endif 1700bfcfaa77SLinus Torvalds 1701200e9ef7SLinus Torvalds /* 17021da177e4SLinus Torvalds * Name resolution. 1703ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1704ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 17051da177e4SLinus Torvalds * 1706ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1707ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 17081da177e4SLinus Torvalds */ 17096de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 17101da177e4SLinus Torvalds { 17111da177e4SLinus Torvalds struct path next; 17121da177e4SLinus Torvalds int err; 17131da177e4SLinus Torvalds 17141da177e4SLinus Torvalds while (*name=='/') 17151da177e4SLinus Torvalds name++; 17161da177e4SLinus Torvalds if (!*name) 1717086e183aSAl Viro return 0; 17181da177e4SLinus Torvalds 17191da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 17201da177e4SLinus Torvalds for(;;) { 17211da177e4SLinus Torvalds struct qstr this; 1722200e9ef7SLinus Torvalds long len; 1723fe479a58SAl Viro int type; 17241da177e4SLinus Torvalds 172552094c8aSAl Viro err = may_lookup(nd); 17261da177e4SLinus Torvalds if (err) 17271da177e4SLinus Torvalds break; 17281da177e4SLinus Torvalds 1729200e9ef7SLinus Torvalds len = hash_name(name, &this.hash); 17301da177e4SLinus Torvalds this.name = name; 1731200e9ef7SLinus Torvalds this.len = len; 17321da177e4SLinus Torvalds 1733fe479a58SAl Viro type = LAST_NORM; 1734200e9ef7SLinus Torvalds if (name[0] == '.') switch (len) { 1735fe479a58SAl Viro case 2: 1736200e9ef7SLinus Torvalds if (name[1] == '.') { 1737fe479a58SAl Viro type = LAST_DOTDOT; 173816c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 173916c2cd71SAl Viro } 1740fe479a58SAl Viro break; 1741fe479a58SAl Viro case 1: 1742fe479a58SAl Viro type = LAST_DOT; 1743fe479a58SAl Viro } 17445a202bcdSAl Viro if (likely(type == LAST_NORM)) { 17455a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 174616c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 17475a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 17485a202bcdSAl Viro err = parent->d_op->d_hash(parent, nd->inode, 17495a202bcdSAl Viro &this); 17505a202bcdSAl Viro if (err < 0) 17515a202bcdSAl Viro break; 17525a202bcdSAl Viro } 17535a202bcdSAl Viro } 1754fe479a58SAl Viro 1755200e9ef7SLinus Torvalds if (!name[len]) 17561da177e4SLinus Torvalds goto last_component; 1757200e9ef7SLinus Torvalds /* 1758200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1759200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1760200e9ef7SLinus Torvalds */ 1761200e9ef7SLinus Torvalds do { 1762200e9ef7SLinus Torvalds len++; 1763200e9ef7SLinus Torvalds } while (unlikely(name[len] == '/')); 1764200e9ef7SLinus Torvalds if (!name[len]) 1765b356379aSAl Viro goto last_component; 1766200e9ef7SLinus Torvalds name += len; 17671da177e4SLinus Torvalds 1768ce57dfc1SAl Viro err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW); 1769ce57dfc1SAl Viro if (err < 0) 1770ce57dfc1SAl Viro return err; 1771fe479a58SAl Viro 1772ce57dfc1SAl Viro if (err) { 1773b356379aSAl Viro err = nested_symlink(&next, nd); 17741da177e4SLinus Torvalds if (err) 1775a7472babSAl Viro return err; 177631e6b01fSNick Piggin } 17773ddcd056SLinus Torvalds if (can_lookup(nd->inode)) 17781da177e4SLinus Torvalds continue; 17793ddcd056SLinus Torvalds err = -ENOTDIR; 17803ddcd056SLinus Torvalds break; 17811da177e4SLinus Torvalds /* here ends the main loop */ 17821da177e4SLinus Torvalds 17831da177e4SLinus Torvalds last_component: 1784ce57dfc1SAl Viro nd->last = this; 1785ce57dfc1SAl Viro nd->last_type = type; 1786ce57dfc1SAl Viro return 0; 1787ce57dfc1SAl Viro } 1788951361f9SAl Viro terminate_walk(nd); 17891da177e4SLinus Torvalds return err; 17901da177e4SLinus Torvalds } 17911da177e4SLinus Torvalds 179270e9b357SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, 179370e9b357SAl Viro struct nameidata *nd, struct file **fp) 179431e6b01fSNick Piggin { 179531e6b01fSNick Piggin int retval = 0; 179631e6b01fSNick Piggin int fput_needed; 179731e6b01fSNick Piggin struct file *file; 179831e6b01fSNick Piggin 179931e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 180016c2cd71SAl Viro nd->flags = flags | LOOKUP_JUMPED; 180131e6b01fSNick Piggin nd->depth = 0; 18025b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 18035b6ca027SAl Viro struct inode *inode = nd->root.dentry->d_inode; 180473d049a4SAl Viro if (*name) { 18055b6ca027SAl Viro if (!inode->i_op->lookup) 18065b6ca027SAl Viro return -ENOTDIR; 18075b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 18085b6ca027SAl Viro if (retval) 18095b6ca027SAl Viro return retval; 181073d049a4SAl Viro } 18115b6ca027SAl Viro nd->path = nd->root; 18125b6ca027SAl Viro nd->inode = inode; 18135b6ca027SAl Viro if (flags & LOOKUP_RCU) { 181432a7991bSAl Viro lock_rcu_walk(); 18155b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 18165b6ca027SAl Viro } else { 18175b6ca027SAl Viro path_get(&nd->path); 18185b6ca027SAl Viro } 18195b6ca027SAl Viro return 0; 18205b6ca027SAl Viro } 18215b6ca027SAl Viro 182231e6b01fSNick Piggin nd->root.mnt = NULL; 182331e6b01fSNick Piggin 182431e6b01fSNick Piggin if (*name=='/') { 1825e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 182632a7991bSAl Viro lock_rcu_walk(); 1827e41f7d4eSAl Viro set_root_rcu(nd); 1828e41f7d4eSAl Viro } else { 1829e41f7d4eSAl Viro set_root(nd); 1830e41f7d4eSAl Viro path_get(&nd->root); 1831e41f7d4eSAl Viro } 183231e6b01fSNick Piggin nd->path = nd->root; 183331e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1834e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 183531e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1836c28cc364SNick Piggin unsigned seq; 183731e6b01fSNick Piggin 183832a7991bSAl Viro lock_rcu_walk(); 183931e6b01fSNick Piggin 1840c28cc364SNick Piggin do { 1841c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 184231e6b01fSNick Piggin nd->path = fs->pwd; 1843c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1844c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1845e41f7d4eSAl Viro } else { 1846e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1847e41f7d4eSAl Viro } 184831e6b01fSNick Piggin } else { 184931e6b01fSNick Piggin struct dentry *dentry; 185031e6b01fSNick Piggin 18511abf0c71SAl Viro file = fget_raw_light(dfd, &fput_needed); 185231e6b01fSNick Piggin retval = -EBADF; 185331e6b01fSNick Piggin if (!file) 185431e6b01fSNick Piggin goto out_fail; 185531e6b01fSNick Piggin 185631e6b01fSNick Piggin dentry = file->f_path.dentry; 185731e6b01fSNick Piggin 1858f52e0c11SAl Viro if (*name) { 185931e6b01fSNick Piggin retval = -ENOTDIR; 186031e6b01fSNick Piggin if (!S_ISDIR(dentry->d_inode->i_mode)) 186131e6b01fSNick Piggin goto fput_fail; 186231e6b01fSNick Piggin 18634ad5abb3SAl Viro retval = inode_permission(dentry->d_inode, MAY_EXEC); 186431e6b01fSNick Piggin if (retval) 186531e6b01fSNick Piggin goto fput_fail; 1866f52e0c11SAl Viro } 186731e6b01fSNick Piggin 186831e6b01fSNick Piggin nd->path = file->f_path; 1869e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 187031e6b01fSNick Piggin if (fput_needed) 187170e9b357SAl Viro *fp = file; 1872c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 187332a7991bSAl Viro lock_rcu_walk(); 18745590ff0dSUlrich Drepper } else { 18755dd784d0SJan Blunck path_get(&file->f_path); 18765590ff0dSUlrich Drepper fput_light(file, fput_needed); 18771da177e4SLinus Torvalds } 1878e41f7d4eSAl Viro } 1879e41f7d4eSAl Viro 188031e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 18819b4a9b14SAl Viro return 0; 18822dfdd266SJosef 'Jeff' Sipek 18839b4a9b14SAl Viro fput_fail: 18849b4a9b14SAl Viro fput_light(file, fput_needed); 18859b4a9b14SAl Viro out_fail: 18869b4a9b14SAl Viro return retval; 18879b4a9b14SAl Viro } 18889b4a9b14SAl Viro 1889bd92d7feSAl Viro static inline int lookup_last(struct nameidata *nd, struct path *path) 1890bd92d7feSAl Viro { 1891bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1892bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1893bd92d7feSAl Viro 1894bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 1895bd92d7feSAl Viro return walk_component(nd, path, &nd->last, nd->last_type, 1896bd92d7feSAl Viro nd->flags & LOOKUP_FOLLOW); 1897bd92d7feSAl Viro } 1898bd92d7feSAl Viro 18999b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1900ee0827cdSAl Viro static int path_lookupat(int dfd, const char *name, 19019b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 19029b4a9b14SAl Viro { 190370e9b357SAl Viro struct file *base = NULL; 1904bd92d7feSAl Viro struct path path; 1905bd92d7feSAl Viro int err; 190631e6b01fSNick Piggin 190731e6b01fSNick Piggin /* 190831e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 190931e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 191031e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 191131e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 191231e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 191331e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 191431e6b01fSNick Piggin * analogue, foo_rcu(). 191531e6b01fSNick Piggin * 191631e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 191731e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 191831e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 191931e6b01fSNick Piggin * be able to complete). 192031e6b01fSNick Piggin */ 1921bd92d7feSAl Viro err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); 1922ee0827cdSAl Viro 1923bd92d7feSAl Viro if (unlikely(err)) 1924bd92d7feSAl Viro return err; 1925ee0827cdSAl Viro 1926ee0827cdSAl Viro current->total_link_count = 0; 1927bd92d7feSAl Viro err = link_path_walk(name, nd); 1928bd92d7feSAl Viro 1929bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 1930bd92d7feSAl Viro err = lookup_last(nd, &path); 1931bd92d7feSAl Viro while (err > 0) { 1932bd92d7feSAl Viro void *cookie; 1933bd92d7feSAl Viro struct path link = path; 1934800179c9SKees Cook err = may_follow_link(&link, nd); 1935800179c9SKees Cook if (unlikely(err)) 1936800179c9SKees Cook break; 1937bd92d7feSAl Viro nd->flags |= LOOKUP_PARENT; 1938574197e0SAl Viro err = follow_link(&link, nd, &cookie); 19396d7b5aaeSAl Viro if (err) 19406d7b5aaeSAl Viro break; 1941bd92d7feSAl Viro err = lookup_last(nd, &path); 1942574197e0SAl Viro put_link(nd, &link, cookie); 1943bd92d7feSAl Viro } 1944bd92d7feSAl Viro } 1945ee0827cdSAl Viro 19469f1fafeeSAl Viro if (!err) 19479f1fafeeSAl Viro err = complete_walk(nd); 1948bd92d7feSAl Viro 1949bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 1950bd92d7feSAl Viro if (!nd->inode->i_op->lookup) { 1951bd92d7feSAl Viro path_put(&nd->path); 1952bd23a539SAl Viro err = -ENOTDIR; 1953bd92d7feSAl Viro } 1954bd92d7feSAl Viro } 195516c2cd71SAl Viro 195670e9b357SAl Viro if (base) 195770e9b357SAl Viro fput(base); 1958ee0827cdSAl Viro 19595b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 196031e6b01fSNick Piggin path_put(&nd->root); 196131e6b01fSNick Piggin nd->root.mnt = NULL; 196231e6b01fSNick Piggin } 1963bd92d7feSAl Viro return err; 196431e6b01fSNick Piggin } 196531e6b01fSNick Piggin 1966ee0827cdSAl Viro static int do_path_lookup(int dfd, const char *name, 1967ee0827cdSAl Viro unsigned int flags, struct nameidata *nd) 1968ee0827cdSAl Viro { 1969ee0827cdSAl Viro int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 1970ee0827cdSAl Viro if (unlikely(retval == -ECHILD)) 1971ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags, nd); 1972ee0827cdSAl Viro if (unlikely(retval == -ESTALE)) 1973ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 1974ee0827cdSAl Viro 197531e6b01fSNick Piggin if (likely(!retval)) { 197631e6b01fSNick Piggin if (unlikely(!audit_dummy_context())) { 197731e6b01fSNick Piggin if (nd->path.dentry && nd->inode) 197831e6b01fSNick Piggin audit_inode(name, nd->path.dentry); 197931e6b01fSNick Piggin } 198031e6b01fSNick Piggin } 1981170aa3d0SUlrich Drepper return retval; 19821da177e4SLinus Torvalds } 19831da177e4SLinus Torvalds 198479714f72SAl Viro /* does lookup, returns the object with parent locked */ 198579714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 19865590ff0dSUlrich Drepper { 198779714f72SAl Viro struct nameidata nd; 198879714f72SAl Viro struct dentry *d; 198979714f72SAl Viro int err = do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, &nd); 199079714f72SAl Viro if (err) 199179714f72SAl Viro return ERR_PTR(err); 199279714f72SAl Viro if (nd.last_type != LAST_NORM) { 199379714f72SAl Viro path_put(&nd.path); 199479714f72SAl Viro return ERR_PTR(-EINVAL); 199579714f72SAl Viro } 199679714f72SAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 19971e0ea001SAl Viro d = __lookup_hash(&nd.last, nd.path.dentry, 0); 199879714f72SAl Viro if (IS_ERR(d)) { 199979714f72SAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 200079714f72SAl Viro path_put(&nd.path); 200179714f72SAl Viro return d; 200279714f72SAl Viro } 200379714f72SAl Viro *path = nd.path; 200479714f72SAl Viro return d; 20055590ff0dSUlrich Drepper } 20065590ff0dSUlrich Drepper 2007d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2008d1811465SAl Viro { 2009d1811465SAl Viro struct nameidata nd; 2010d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 2011d1811465SAl Viro if (!res) 2012d1811465SAl Viro *path = nd.path; 2013d1811465SAl Viro return res; 2014d1811465SAl Viro } 2015d1811465SAl Viro 201616f18200SJosef 'Jeff' Sipek /** 201716f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 201816f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 201916f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 202016f18200SJosef 'Jeff' Sipek * @name: pointer to file name 202116f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2022e0a01249SAl Viro * @path: pointer to struct path to fill 202316f18200SJosef 'Jeff' Sipek */ 202416f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 202516f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2026e0a01249SAl Viro struct path *path) 202716f18200SJosef 'Jeff' Sipek { 2028e0a01249SAl Viro struct nameidata nd; 2029e0a01249SAl Viro int err; 2030e0a01249SAl Viro nd.root.dentry = dentry; 2031e0a01249SAl Viro nd.root.mnt = mnt; 2032e0a01249SAl Viro BUG_ON(flags & LOOKUP_PARENT); 20335b6ca027SAl Viro /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ 2034e0a01249SAl Viro err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd); 2035e0a01249SAl Viro if (!err) 2036e0a01249SAl Viro *path = nd.path; 2037e0a01249SAl Viro return err; 203816f18200SJosef 'Jeff' Sipek } 203916f18200SJosef 'Jeff' Sipek 2040057f6c01SJames Morris /* 2041057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 2042057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 2043057f6c01SJames Morris * SMP-safe. 2044057f6c01SJames Morris */ 2045a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 20461da177e4SLinus Torvalds { 204772bd866aSAl Viro return __lookup_hash(&nd->last, nd->path.dentry, nd->flags); 20481da177e4SLinus Torvalds } 20491da177e4SLinus Torvalds 2050eead1911SChristoph Hellwig /** 2051a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2052eead1911SChristoph Hellwig * @name: pathname component to lookup 2053eead1911SChristoph Hellwig * @base: base directory to lookup from 2054eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2055eead1911SChristoph Hellwig * 2056a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 2057a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 2058eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 2059eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 2060eead1911SChristoph Hellwig */ 2061057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2062057f6c01SJames Morris { 2063057f6c01SJames Morris struct qstr this; 20646a96ba54SAl Viro unsigned int c; 2065cda309deSMiklos Szeredi int err; 2066057f6c01SJames Morris 20672f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 20682f9092e1SDavid Woodhouse 20696a96ba54SAl Viro this.name = name; 20706a96ba54SAl Viro this.len = len; 20710145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 20726a96ba54SAl Viro if (!len) 20736a96ba54SAl Viro return ERR_PTR(-EACCES); 20746a96ba54SAl Viro 20756a96ba54SAl Viro while (len--) { 20766a96ba54SAl Viro c = *(const unsigned char *)name++; 20776a96ba54SAl Viro if (c == '/' || c == '\0') 20786a96ba54SAl Viro return ERR_PTR(-EACCES); 20796a96ba54SAl Viro } 20805a202bcdSAl Viro /* 20815a202bcdSAl Viro * See if the low-level filesystem might want 20825a202bcdSAl Viro * to use its own hash.. 20835a202bcdSAl Viro */ 20845a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 20855a202bcdSAl Viro int err = base->d_op->d_hash(base, base->d_inode, &this); 20865a202bcdSAl Viro if (err < 0) 20875a202bcdSAl Viro return ERR_PTR(err); 20885a202bcdSAl Viro } 2089eead1911SChristoph Hellwig 2090cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2091cda309deSMiklos Szeredi if (err) 2092cda309deSMiklos Szeredi return ERR_PTR(err); 2093cda309deSMiklos Szeredi 209472bd866aSAl Viro return __lookup_hash(&this, base, 0); 2095057f6c01SJames Morris } 2096057f6c01SJames Morris 20971fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 20981fa1e7f6SAndy Whitcroft struct path *path, int *empty) 20991da177e4SLinus Torvalds { 21002d8f3038SAl Viro struct nameidata nd; 21011fa1e7f6SAndy Whitcroft char *tmp = getname_flags(name, flags, empty); 21021da177e4SLinus Torvalds int err = PTR_ERR(tmp); 21031da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 21042d8f3038SAl Viro 21052d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 21062d8f3038SAl Viro 21072d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 21081da177e4SLinus Torvalds putname(tmp); 21092d8f3038SAl Viro if (!err) 21102d8f3038SAl Viro *path = nd.path; 21111da177e4SLinus Torvalds } 21121da177e4SLinus Torvalds return err; 21131da177e4SLinus Torvalds } 21141da177e4SLinus Torvalds 21151fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 21161fa1e7f6SAndy Whitcroft struct path *path) 21171fa1e7f6SAndy Whitcroft { 2118f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 21191fa1e7f6SAndy Whitcroft } 21201fa1e7f6SAndy Whitcroft 21212ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 21222ad94ae6SAl Viro struct nameidata *nd, char **name) 21232ad94ae6SAl Viro { 21242ad94ae6SAl Viro char *s = getname(path); 21252ad94ae6SAl Viro int error; 21262ad94ae6SAl Viro 21272ad94ae6SAl Viro if (IS_ERR(s)) 21282ad94ae6SAl Viro return PTR_ERR(s); 21292ad94ae6SAl Viro 21302ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 21312ad94ae6SAl Viro if (error) 21322ad94ae6SAl Viro putname(s); 21332ad94ae6SAl Viro else 21342ad94ae6SAl Viro *name = s; 21352ad94ae6SAl Viro 21362ad94ae6SAl Viro return error; 21372ad94ae6SAl Viro } 21382ad94ae6SAl Viro 21391da177e4SLinus Torvalds /* 21401da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 21411da177e4SLinus Torvalds * minimal. 21421da177e4SLinus Torvalds */ 21431da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 21441da177e4SLinus Torvalds { 21458e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2146da9592edSDavid Howells 21471da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 21481da177e4SLinus Torvalds return 0; 21498e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 21501da177e4SLinus Torvalds return 0; 21518e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 21521da177e4SLinus Torvalds return 0; 21531a48e2acSEric W. Biederman return !inode_capable(inode, CAP_FOWNER); 21541da177e4SLinus Torvalds } 21551da177e4SLinus Torvalds 21561da177e4SLinus Torvalds /* 21571da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 21581da177e4SLinus Torvalds * whether the type of victim is right. 21591da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 21601da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 21611da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 21621da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 21631da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 21641da177e4SLinus Torvalds * a. be owner of dir, or 21651da177e4SLinus Torvalds * b. be owner of victim, or 21661da177e4SLinus Torvalds * c. have CAP_FOWNER capability 21671da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 21681da177e4SLinus Torvalds * links pointing to it. 21691da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 21701da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 21711da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 21721da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 21731da177e4SLinus Torvalds * nfs_async_unlink(). 21741da177e4SLinus Torvalds */ 2175858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 21761da177e4SLinus Torvalds { 21771da177e4SLinus Torvalds int error; 21781da177e4SLinus Torvalds 21791da177e4SLinus Torvalds if (!victim->d_inode) 21801da177e4SLinus Torvalds return -ENOENT; 21811da177e4SLinus Torvalds 21821da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 2183cccc6bbaSAl Viro audit_inode_child(victim, dir); 21841da177e4SLinus Torvalds 2185f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 21861da177e4SLinus Torvalds if (error) 21871da177e4SLinus Torvalds return error; 21881da177e4SLinus Torvalds if (IS_APPEND(dir)) 21891da177e4SLinus Torvalds return -EPERM; 21901da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 2191f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 21921da177e4SLinus Torvalds return -EPERM; 21931da177e4SLinus Torvalds if (isdir) { 21941da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 21951da177e4SLinus Torvalds return -ENOTDIR; 21961da177e4SLinus Torvalds if (IS_ROOT(victim)) 21971da177e4SLinus Torvalds return -EBUSY; 21981da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 21991da177e4SLinus Torvalds return -EISDIR; 22001da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 22011da177e4SLinus Torvalds return -ENOENT; 22021da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 22031da177e4SLinus Torvalds return -EBUSY; 22041da177e4SLinus Torvalds return 0; 22051da177e4SLinus Torvalds } 22061da177e4SLinus Torvalds 22071da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 22081da177e4SLinus Torvalds * dir. 22091da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 22101da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 22111da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 22121da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 22131da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 22141da177e4SLinus Torvalds */ 2215a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 22161da177e4SLinus Torvalds { 22171da177e4SLinus Torvalds if (child->d_inode) 22181da177e4SLinus Torvalds return -EEXIST; 22191da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 22201da177e4SLinus Torvalds return -ENOENT; 2221f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 22221da177e4SLinus Torvalds } 22231da177e4SLinus Torvalds 22241da177e4SLinus Torvalds /* 22251da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 22261da177e4SLinus Torvalds */ 22271da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 22281da177e4SLinus Torvalds { 22291da177e4SLinus Torvalds struct dentry *p; 22301da177e4SLinus Torvalds 22311da177e4SLinus Torvalds if (p1 == p2) { 2232f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 22331da177e4SLinus Torvalds return NULL; 22341da177e4SLinus Torvalds } 22351da177e4SLinus Torvalds 2236a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 22371da177e4SLinus Torvalds 2238e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2239e2761a11SOGAWA Hirofumi if (p) { 2240f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2241f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 22421da177e4SLinus Torvalds return p; 22431da177e4SLinus Torvalds } 22441da177e4SLinus Torvalds 2245e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2246e2761a11SOGAWA Hirofumi if (p) { 2247f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2248f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 22491da177e4SLinus Torvalds return p; 22501da177e4SLinus Torvalds } 22511da177e4SLinus Torvalds 2252f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2253f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 22541da177e4SLinus Torvalds return NULL; 22551da177e4SLinus Torvalds } 22561da177e4SLinus Torvalds 22571da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 22581da177e4SLinus Torvalds { 22591b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 22601da177e4SLinus Torvalds if (p1 != p2) { 22611b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2262a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 22631da177e4SLinus Torvalds } 22641da177e4SLinus Torvalds } 22651da177e4SLinus Torvalds 22664acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2267312b63fbSAl Viro bool want_excl) 22681da177e4SLinus Torvalds { 2269a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 22701da177e4SLinus Torvalds if (error) 22711da177e4SLinus Torvalds return error; 22721da177e4SLinus Torvalds 2273acfa4380SAl Viro if (!dir->i_op->create) 22741da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 22751da177e4SLinus Torvalds mode &= S_IALLUGO; 22761da177e4SLinus Torvalds mode |= S_IFREG; 22771da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 22781da177e4SLinus Torvalds if (error) 22791da177e4SLinus Torvalds return error; 2280312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2281a74574aaSStephen Smalley if (!error) 2282f38aa942SAmy Griffis fsnotify_create(dir, dentry); 22831da177e4SLinus Torvalds return error; 22841da177e4SLinus Torvalds } 22851da177e4SLinus Torvalds 228673d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 22871da177e4SLinus Torvalds { 22883fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 22891da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 22901da177e4SLinus Torvalds int error; 22911da177e4SLinus Torvalds 2292bcda7652SAl Viro /* O_PATH? */ 2293bcda7652SAl Viro if (!acc_mode) 2294bcda7652SAl Viro return 0; 2295bcda7652SAl Viro 22961da177e4SLinus Torvalds if (!inode) 22971da177e4SLinus Torvalds return -ENOENT; 22981da177e4SLinus Torvalds 2299c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2300c8fe8f30SChristoph Hellwig case S_IFLNK: 23011da177e4SLinus Torvalds return -ELOOP; 2302c8fe8f30SChristoph Hellwig case S_IFDIR: 2303c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 23041da177e4SLinus Torvalds return -EISDIR; 2305c8fe8f30SChristoph Hellwig break; 2306c8fe8f30SChristoph Hellwig case S_IFBLK: 2307c8fe8f30SChristoph Hellwig case S_IFCHR: 23083fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 23091da177e4SLinus Torvalds return -EACCES; 2310c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2311c8fe8f30SChristoph Hellwig case S_IFIFO: 2312c8fe8f30SChristoph Hellwig case S_IFSOCK: 23131da177e4SLinus Torvalds flag &= ~O_TRUNC; 2314c8fe8f30SChristoph Hellwig break; 23154a3fd211SDave Hansen } 2316b41572e9SDave Hansen 23173fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2318b41572e9SDave Hansen if (error) 2319b41572e9SDave Hansen return error; 23206146f0d5SMimi Zohar 23211da177e4SLinus Torvalds /* 23221da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 23231da177e4SLinus Torvalds */ 23241da177e4SLinus Torvalds if (IS_APPEND(inode)) { 23258737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 23267715b521SAl Viro return -EPERM; 23271da177e4SLinus Torvalds if (flag & O_TRUNC) 23287715b521SAl Viro return -EPERM; 23291da177e4SLinus Torvalds } 23301da177e4SLinus Torvalds 23311da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 23322e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 23337715b521SAl Viro return -EPERM; 23341da177e4SLinus Torvalds 2335f3c7691eSJ. Bruce Fields return 0; 23367715b521SAl Viro } 23377715b521SAl Viro 2338e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 23397715b521SAl Viro { 2340e1181ee6SJeff Layton struct path *path = &filp->f_path; 23417715b521SAl Viro struct inode *inode = path->dentry->d_inode; 23427715b521SAl Viro int error = get_write_access(inode); 23431da177e4SLinus Torvalds if (error) 23447715b521SAl Viro return error; 23451da177e4SLinus Torvalds /* 23461da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 23471da177e4SLinus Torvalds */ 23481da177e4SLinus Torvalds error = locks_verify_locked(inode); 2349be6d3e56SKentaro Takeda if (!error) 2350ea0d3ab2STetsuo Handa error = security_path_truncate(path); 23511da177e4SLinus Torvalds if (!error) { 23527715b521SAl Viro error = do_truncate(path->dentry, 0, 2353d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2354e1181ee6SJeff Layton filp); 23551da177e4SLinus Torvalds } 23561da177e4SLinus Torvalds put_write_access(inode); 2357acd0c935SMimi Zohar return error; 23581da177e4SLinus Torvalds } 23591da177e4SLinus Torvalds 2360d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2361d57999e1SDave Hansen { 23628a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 23638a5e929dSAl Viro flag--; 2364d57999e1SDave Hansen return flag; 2365d57999e1SDave Hansen } 2366d57999e1SDave Hansen 2367d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2368d18e9008SMiklos Szeredi { 2369d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2370d18e9008SMiklos Szeredi if (error) 2371d18e9008SMiklos Szeredi return error; 2372d18e9008SMiklos Szeredi 2373d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2374d18e9008SMiklos Szeredi if (error) 2375d18e9008SMiklos Szeredi return error; 2376d18e9008SMiklos Szeredi 2377d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2378d18e9008SMiklos Szeredi } 2379d18e9008SMiklos Szeredi 23801acf0af9SDavid Howells /* 23811acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 23821acf0af9SDavid Howells * dentry. 23831acf0af9SDavid Howells * 23841acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 23851acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 23861acf0af9SDavid Howells * 23871acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 23881acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 23891acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 23901acf0af9SDavid Howells * 23911acf0af9SDavid Howells * Returns an error code otherwise. 23921acf0af9SDavid Howells */ 23932675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 239430d90494SAl Viro struct path *path, struct file *file, 2395015c3bbcSMiklos Szeredi const struct open_flags *op, 239677d660a8SMiklos Szeredi bool *want_write, bool need_lookup, 239747237687SAl Viro int *opened) 2398d18e9008SMiklos Szeredi { 2399d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2400d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2401d18e9008SMiklos Szeredi umode_t mode; 2402d18e9008SMiklos Szeredi int error; 2403d18e9008SMiklos Szeredi int acc_mode; 2404d18e9008SMiklos Szeredi int create_error = 0; 2405d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2406d18e9008SMiklos Szeredi 2407d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2408d18e9008SMiklos Szeredi 2409d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2410d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 24112675a4ebSAl Viro error = -ENOENT; 2412d18e9008SMiklos Szeredi goto out; 2413d18e9008SMiklos Szeredi } 2414d18e9008SMiklos Szeredi 2415d18e9008SMiklos Szeredi mode = op->mode & S_IALLUGO; 2416d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2417d18e9008SMiklos Szeredi mode &= ~current_umask(); 2418d18e9008SMiklos Szeredi 2419d18e9008SMiklos Szeredi if (open_flag & O_EXCL) { 2420d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 242147237687SAl Viro *opened |= FILE_CREATED; 2422d18e9008SMiklos Szeredi } 2423d18e9008SMiklos Szeredi 2424d18e9008SMiklos Szeredi /* 2425d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2426d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2427d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2428d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2429d18e9008SMiklos Szeredi * 2430d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2431d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2432d18e9008SMiklos Szeredi */ 2433d18e9008SMiklos Szeredi if ((open_flag & (O_CREAT | O_TRUNC)) || 2434d18e9008SMiklos Szeredi (open_flag & O_ACCMODE) != O_RDONLY) { 2435d18e9008SMiklos Szeredi error = mnt_want_write(nd->path.mnt); 2436d18e9008SMiklos Szeredi if (!error) { 243777d660a8SMiklos Szeredi *want_write = true; 2438d18e9008SMiklos Szeredi } else if (!(open_flag & O_CREAT)) { 2439d18e9008SMiklos Szeredi /* 2440d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2441d18e9008SMiklos Szeredi * back to lookup + open 2442d18e9008SMiklos Szeredi */ 2443d18e9008SMiklos Szeredi goto no_open; 2444d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2445d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 2446d18e9008SMiklos Szeredi create_error = error; 2447d18e9008SMiklos Szeredi goto no_open; 2448d18e9008SMiklos Szeredi } else { 2449d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 2450d18e9008SMiklos Szeredi create_error = error; 2451d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2452d18e9008SMiklos Szeredi } 2453d18e9008SMiklos Szeredi } 2454d18e9008SMiklos Szeredi 2455d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 2456d18e9008SMiklos Szeredi error = may_o_create(&nd->path, dentry, op->mode); 2457d18e9008SMiklos Szeredi if (error) { 2458d18e9008SMiklos Szeredi create_error = error; 2459d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2460d18e9008SMiklos Szeredi goto no_open; 2461d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2462d18e9008SMiklos Szeredi } 2463d18e9008SMiklos Szeredi } 2464d18e9008SMiklos Szeredi 2465d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2466d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2467d18e9008SMiklos Szeredi 246830d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 246930d90494SAl Viro file->f_path.mnt = nd->path.mnt; 247030d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 247147237687SAl Viro opened); 2472d9585277SAl Viro if (error < 0) { 2473d9585277SAl Viro if (create_error && error == -ENOENT) 2474d9585277SAl Viro error = create_error; 2475d18e9008SMiklos Szeredi goto out; 2476d18e9008SMiklos Szeredi } 2477d18e9008SMiklos Szeredi 2478d18e9008SMiklos Szeredi acc_mode = op->acc_mode; 247947237687SAl Viro if (*opened & FILE_CREATED) { 2480d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 2481d18e9008SMiklos Szeredi acc_mode = MAY_OPEN; 2482d18e9008SMiklos Szeredi } 2483d18e9008SMiklos Szeredi 2484d9585277SAl Viro if (error) { /* returned 1, that is */ 248530d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 24862675a4ebSAl Viro error = -EIO; 2487d18e9008SMiklos Szeredi goto out; 2488d18e9008SMiklos Szeredi } 248930d90494SAl Viro if (file->f_path.dentry) { 2490d18e9008SMiklos Szeredi dput(dentry); 249130d90494SAl Viro dentry = file->f_path.dentry; 2492d18e9008SMiklos Szeredi } 2493d18e9008SMiklos Szeredi goto looked_up; 2494d18e9008SMiklos Szeredi } 2495d18e9008SMiklos Szeredi 2496d18e9008SMiklos Szeredi /* 2497d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2498d18e9008SMiklos Szeredi * here. 2499d18e9008SMiklos Szeredi */ 25002675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 25012675a4ebSAl Viro if (error) 25022675a4ebSAl Viro fput(file); 2503d18e9008SMiklos Szeredi 2504d18e9008SMiklos Szeredi out: 2505d18e9008SMiklos Szeredi dput(dentry); 25062675a4ebSAl Viro return error; 2507d18e9008SMiklos Szeredi 2508d18e9008SMiklos Szeredi no_open: 2509d18e9008SMiklos Szeredi if (need_lookup) { 251072bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2511d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 25122675a4ebSAl Viro return PTR_ERR(dentry); 2513d18e9008SMiklos Szeredi 2514d18e9008SMiklos Szeredi if (create_error) { 2515d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2516d18e9008SMiklos Szeredi 25172675a4ebSAl Viro error = create_error; 2518d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2519d18e9008SMiklos Szeredi if (!dentry->d_inode) 2520d18e9008SMiklos Szeredi goto out; 2521d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2522d18e9008SMiklos Szeredi goto out; 2523d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2524d18e9008SMiklos Szeredi S_ISREG(dentry->d_inode->i_mode)) { 2525d18e9008SMiklos Szeredi goto out; 2526d18e9008SMiklos Szeredi } 2527d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2528d18e9008SMiklos Szeredi } 2529d18e9008SMiklos Szeredi } 2530d18e9008SMiklos Szeredi looked_up: 2531d18e9008SMiklos Szeredi path->dentry = dentry; 2532d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 25332675a4ebSAl Viro return 1; 2534d18e9008SMiklos Szeredi } 2535d18e9008SMiklos Szeredi 253631e6b01fSNick Piggin /* 25371acf0af9SDavid Howells * Look up and maybe create and open the last component. 2538d58ffd35SMiklos Szeredi * 2539d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2540d58ffd35SMiklos Szeredi * 25411acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 25421acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 25431acf0af9SDavid Howells * 25441acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 25451acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 25461acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 25471acf0af9SDavid Howells * specified then a negative dentry may be returned. 25481acf0af9SDavid Howells * 25491acf0af9SDavid Howells * An error code is returned otherwise. 25501acf0af9SDavid Howells * 25511acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 25521acf0af9SDavid Howells * cleared otherwise prior to returning. 2553d58ffd35SMiklos Szeredi */ 25542675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 255530d90494SAl Viro struct file *file, 2556d58ffd35SMiklos Szeredi const struct open_flags *op, 255747237687SAl Viro bool *want_write, int *opened) 2558d58ffd35SMiklos Szeredi { 2559d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 256054ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2561d58ffd35SMiklos Szeredi struct dentry *dentry; 2562d58ffd35SMiklos Szeredi int error; 256354ef4872SMiklos Szeredi bool need_lookup; 2564d58ffd35SMiklos Szeredi 256547237687SAl Viro *opened &= ~FILE_CREATED; 2566201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2567d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 25682675a4ebSAl Viro return PTR_ERR(dentry); 2569d58ffd35SMiklos Szeredi 2570d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2571d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2572d18e9008SMiklos Szeredi goto out_no_open; 2573d18e9008SMiklos Szeredi 2574d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 257530d90494SAl Viro return atomic_open(nd, dentry, path, file, op, want_write, 257647237687SAl Viro need_lookup, opened); 2577d18e9008SMiklos Szeredi } 2578d18e9008SMiklos Szeredi 257954ef4872SMiklos Szeredi if (need_lookup) { 258054ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 258154ef4872SMiklos Szeredi 258272bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 258354ef4872SMiklos Szeredi if (IS_ERR(dentry)) 25842675a4ebSAl Viro return PTR_ERR(dentry); 258554ef4872SMiklos Szeredi } 258654ef4872SMiklos Szeredi 2587d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2588d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2589d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2590d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2591d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2592d58ffd35SMiklos Szeredi /* 2593d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2594d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2595d58ffd35SMiklos Szeredi * the time when the file is created and when 2596d58ffd35SMiklos Szeredi * a permanent write count is taken through 2597015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 2598d58ffd35SMiklos Szeredi */ 2599d58ffd35SMiklos Szeredi error = mnt_want_write(nd->path.mnt); 2600d58ffd35SMiklos Szeredi if (error) 2601d58ffd35SMiklos Szeredi goto out_dput; 260277d660a8SMiklos Szeredi *want_write = true; 260347237687SAl Viro *opened |= FILE_CREATED; 2604d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2605d58ffd35SMiklos Szeredi if (error) 2606d58ffd35SMiklos Szeredi goto out_dput; 2607312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 2608312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 2609d58ffd35SMiklos Szeredi if (error) 2610d58ffd35SMiklos Szeredi goto out_dput; 2611d58ffd35SMiklos Szeredi } 2612d18e9008SMiklos Szeredi out_no_open: 2613d58ffd35SMiklos Szeredi path->dentry = dentry; 2614d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 26152675a4ebSAl Viro return 1; 2616d58ffd35SMiklos Szeredi 2617d58ffd35SMiklos Szeredi out_dput: 2618d58ffd35SMiklos Szeredi dput(dentry); 26192675a4ebSAl Viro return error; 2620d58ffd35SMiklos Szeredi } 2621d58ffd35SMiklos Szeredi 2622d58ffd35SMiklos Szeredi /* 2623fe2d35ffSAl Viro * Handle the last step of open() 262431e6b01fSNick Piggin */ 26252675a4ebSAl Viro static int do_last(struct nameidata *nd, struct path *path, 262630d90494SAl Viro struct file *file, const struct open_flags *op, 262747237687SAl Viro int *opened, const char *pathname) 2628fb1cc555SAl Viro { 2629a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2630ca344a89SAl Viro int open_flag = op->open_flag; 263177d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 263277d660a8SMiklos Szeredi bool want_write = false; 2633bcda7652SAl Viro int acc_mode = op->acc_mode; 2634a1eb3315SMiklos Szeredi struct inode *inode; 263577d660a8SMiklos Szeredi bool symlink_ok = false; 263616b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 263716b1c1cdSMiklos Szeredi bool retried = false; 263816c2cd71SAl Viro int error; 2639fb1cc555SAl Viro 2640c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2641c3e380b0SAl Viro nd->flags |= op->intent; 2642c3e380b0SAl Viro 26431f36f774SAl Viro switch (nd->last_type) { 26441f36f774SAl Viro case LAST_DOTDOT: 2645176306f5SNeil Brown case LAST_DOT: 2646fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2647fe2d35ffSAl Viro if (error) 26482675a4ebSAl Viro return error; 26491f36f774SAl Viro /* fallthrough */ 26501f36f774SAl Viro case LAST_ROOT: 26519f1fafeeSAl Viro error = complete_walk(nd); 265216c2cd71SAl Viro if (error) 26532675a4ebSAl Viro return error; 2654fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2655ca344a89SAl Viro if (open_flag & O_CREAT) { 265616c2cd71SAl Viro error = -EISDIR; 26572675a4ebSAl Viro goto out; 2658fe2d35ffSAl Viro } 2659e83db167SMiklos Szeredi goto finish_open; 26601f36f774SAl Viro case LAST_BIND: 26619f1fafeeSAl Viro error = complete_walk(nd); 266216c2cd71SAl Viro if (error) 26632675a4ebSAl Viro return error; 26641f36f774SAl Viro audit_inode(pathname, dir); 2665e83db167SMiklos Szeredi goto finish_open; 26661f36f774SAl Viro } 2667a2c36b45SAl Viro 2668ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2669fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2670fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2671bcda7652SAl Viro if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) 267277d660a8SMiklos Szeredi symlink_ok = true; 2673fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2674a1eb3315SMiklos Szeredi error = lookup_fast(nd, &nd->last, path, &inode); 267571574865SMiklos Szeredi if (likely(!error)) 267671574865SMiklos Szeredi goto finish_lookup; 267771574865SMiklos Szeredi 2678ce57dfc1SAl Viro if (error < 0) 26792675a4ebSAl Viro goto out; 2680a1eb3315SMiklos Szeredi 268137d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 2682b6183df7SMiklos Szeredi } else { 2683fe2d35ffSAl Viro /* create side of things */ 2684a3fbbde7SAl Viro /* 2685b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 2686b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 2687b6183df7SMiklos Szeredi * about to look up 2688a3fbbde7SAl Viro */ 26899f1fafeeSAl Viro error = complete_walk(nd); 26909f1fafeeSAl Viro if (error) 26912675a4ebSAl Viro return error; 2692fe2d35ffSAl Viro 2693fe2d35ffSAl Viro audit_inode(pathname, dir); 269416c2cd71SAl Viro error = -EISDIR; 26951f36f774SAl Viro /* trailing slashes? */ 269631e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 26972675a4ebSAl Viro goto out; 2698b6183df7SMiklos Szeredi } 26991f36f774SAl Viro 270016b1c1cdSMiklos Szeredi retry_lookup: 2701a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 27022675a4ebSAl Viro error = lookup_open(nd, path, file, op, &want_write, opened); 2703fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2704fb1cc555SAl Viro 27052675a4ebSAl Viro if (error <= 0) { 27062675a4ebSAl Viro if (error) 2707d58ffd35SMiklos Szeredi goto out; 27086c0d46c4SAl Viro 270947237687SAl Viro if ((*opened & FILE_CREATED) || 27102675a4ebSAl Viro !S_ISREG(file->f_path.dentry->d_inode->i_mode)) 271177d660a8SMiklos Szeredi will_truncate = false; 2712d18e9008SMiklos Szeredi 27132675a4ebSAl Viro audit_inode(pathname, file->f_path.dentry); 2714d18e9008SMiklos Szeredi goto opened; 2715d18e9008SMiklos Szeredi } 2716d18e9008SMiklos Szeredi 271747237687SAl Viro if (*opened & FILE_CREATED) { 27189b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 2719ca344a89SAl Viro open_flag &= ~O_TRUNC; 272077d660a8SMiklos Szeredi will_truncate = false; 2721bcda7652SAl Viro acc_mode = MAY_OPEN; 2722d58ffd35SMiklos Szeredi path_to_nameidata(path, nd); 2723e83db167SMiklos Szeredi goto finish_open_created; 2724fb1cc555SAl Viro } 2725fb1cc555SAl Viro 2726fb1cc555SAl Viro /* 27273134f37eSJeff Layton * create/update audit record if it already exists. 2728fb1cc555SAl Viro */ 27293134f37eSJeff Layton if (path->dentry->d_inode) 2730fb1cc555SAl Viro audit_inode(pathname, path->dentry); 2731fb1cc555SAl Viro 2732d18e9008SMiklos Szeredi /* 2733d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 2734d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 2735d18e9008SMiklos Szeredi * necessary...) 2736d18e9008SMiklos Szeredi */ 2737d18e9008SMiklos Szeredi if (want_write) { 2738d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 273977d660a8SMiklos Szeredi want_write = false; 2740d18e9008SMiklos Szeredi } 2741d18e9008SMiklos Szeredi 2742fb1cc555SAl Viro error = -EEXIST; 2743ca344a89SAl Viro if (open_flag & O_EXCL) 2744fb1cc555SAl Viro goto exit_dput; 2745fb1cc555SAl Viro 27469875cf80SDavid Howells error = follow_managed(path, nd->flags); 27479875cf80SDavid Howells if (error < 0) 2748fb1cc555SAl Viro goto exit_dput; 2749fb1cc555SAl Viro 2750a3fbbde7SAl Viro if (error) 2751a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 2752a3fbbde7SAl Viro 2753decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 2754decf3400SMiklos Szeredi inode = path->dentry->d_inode; 27555f5daac1SMiklos Szeredi finish_lookup: 27565f5daac1SMiklos Szeredi /* we _can_ be in RCU mode here */ 2757fb1cc555SAl Viro error = -ENOENT; 275854c33e7fSMiklos Szeredi if (!inode) { 275954c33e7fSMiklos Szeredi path_to_nameidata(path, nd); 27602675a4ebSAl Viro goto out; 276154c33e7fSMiklos Szeredi } 27629e67f361SAl Viro 2763d45ea867SMiklos Szeredi if (should_follow_link(inode, !symlink_ok)) { 2764d45ea867SMiklos Szeredi if (nd->flags & LOOKUP_RCU) { 2765d45ea867SMiklos Szeredi if (unlikely(unlazy_walk(nd, path->dentry))) { 2766d45ea867SMiklos Szeredi error = -ECHILD; 27672675a4ebSAl Viro goto out; 2768d45ea867SMiklos Szeredi } 2769d45ea867SMiklos Szeredi } 2770d45ea867SMiklos Szeredi BUG_ON(inode != path->dentry->d_inode); 27712675a4ebSAl Viro return 1; 2772d45ea867SMiklos Szeredi } 2773fb1cc555SAl Viro 277416b1c1cdSMiklos Szeredi if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path->mnt) { 2775fb1cc555SAl Viro path_to_nameidata(path, nd); 277616b1c1cdSMiklos Szeredi } else { 277716b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 277816b1c1cdSMiklos Szeredi save_parent.mnt = mntget(path->mnt); 277916b1c1cdSMiklos Szeredi nd->path.dentry = path->dentry; 278016b1c1cdSMiklos Szeredi 278116b1c1cdSMiklos Szeredi } 2782decf3400SMiklos Szeredi nd->inode = inode; 2783a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 2784a3fbbde7SAl Viro error = complete_walk(nd); 278516b1c1cdSMiklos Szeredi if (error) { 278616b1c1cdSMiklos Szeredi path_put(&save_parent); 27872675a4ebSAl Viro return error; 278816b1c1cdSMiklos Szeredi } 2789fb1cc555SAl Viro error = -EISDIR; 2790050ac841SMiklos Szeredi if ((open_flag & O_CREAT) && S_ISDIR(nd->inode->i_mode)) 27912675a4ebSAl Viro goto out; 2792af2f5542SMiklos Szeredi error = -ENOTDIR; 2793af2f5542SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !nd->inode->i_op->lookup) 27942675a4ebSAl Viro goto out; 2795d7fdd7f6SMiklos Szeredi audit_inode(pathname, nd->path.dentry); 2796e83db167SMiklos Szeredi finish_open: 27976c0d46c4SAl Viro if (!S_ISREG(nd->inode->i_mode)) 279877d660a8SMiklos Szeredi will_truncate = false; 27996c0d46c4SAl Viro 28000f9d1a10SAl Viro if (will_truncate) { 28010f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 28020f9d1a10SAl Viro if (error) 28032675a4ebSAl Viro goto out; 280477d660a8SMiklos Szeredi want_write = true; 28050f9d1a10SAl Viro } 2806e83db167SMiklos Szeredi finish_open_created: 2807bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 2808ca344a89SAl Viro if (error) 28092675a4ebSAl Viro goto out; 281030d90494SAl Viro file->f_path.mnt = nd->path.mnt; 281130d90494SAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 281230d90494SAl Viro if (error) { 281330d90494SAl Viro if (error == -EOPENSTALE) 2814f60dc3dbSMiklos Szeredi goto stale_open; 2815015c3bbcSMiklos Szeredi goto out; 2816f60dc3dbSMiklos Szeredi } 2817a8277b9bSMiklos Szeredi opened: 28182675a4ebSAl Viro error = open_check_o_direct(file); 2819015c3bbcSMiklos Szeredi if (error) 2820015c3bbcSMiklos Szeredi goto exit_fput; 28212675a4ebSAl Viro error = ima_file_check(file, op->acc_mode); 2822aa4caadbSMiklos Szeredi if (error) 2823aa4caadbSMiklos Szeredi goto exit_fput; 2824aa4caadbSMiklos Szeredi 28250f9d1a10SAl Viro if (will_truncate) { 28262675a4ebSAl Viro error = handle_truncate(file); 2827aa4caadbSMiklos Szeredi if (error) 2828aa4caadbSMiklos Szeredi goto exit_fput; 28290f9d1a10SAl Viro } 2830ca344a89SAl Viro out: 2831ca344a89SAl Viro if (want_write) 28320f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 283316b1c1cdSMiklos Szeredi path_put(&save_parent); 2834e276ae67SMiklos Szeredi terminate_walk(nd); 28352675a4ebSAl Viro return error; 2836fb1cc555SAl Viro 2837fb1cc555SAl Viro exit_dput: 2838fb1cc555SAl Viro path_put_conditional(path, nd); 2839ca344a89SAl Viro goto out; 2840015c3bbcSMiklos Szeredi exit_fput: 28412675a4ebSAl Viro fput(file); 28422675a4ebSAl Viro goto out; 2843015c3bbcSMiklos Szeredi 2844f60dc3dbSMiklos Szeredi stale_open: 2845f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 2846f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 2847f60dc3dbSMiklos Szeredi goto out; 2848f60dc3dbSMiklos Szeredi 2849f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 2850f60dc3dbSMiklos Szeredi path_put(&nd->path); 2851f60dc3dbSMiklos Szeredi nd->path = save_parent; 2852f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 2853f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 2854f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 2855f60dc3dbSMiklos Szeredi if (want_write) { 2856f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 2857f60dc3dbSMiklos Szeredi want_write = false; 2858f60dc3dbSMiklos Szeredi } 2859f60dc3dbSMiklos Szeredi retried = true; 2860f60dc3dbSMiklos Szeredi goto retry_lookup; 2861fb1cc555SAl Viro } 2862fb1cc555SAl Viro 286313aab428SAl Viro static struct file *path_openat(int dfd, const char *pathname, 286473d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 28651da177e4SLinus Torvalds { 2866fe2d35ffSAl Viro struct file *base = NULL; 286730d90494SAl Viro struct file *file; 28689850c056SAl Viro struct path path; 286947237687SAl Viro int opened = 0; 287013aab428SAl Viro int error; 287131e6b01fSNick Piggin 287230d90494SAl Viro file = get_empty_filp(); 287330d90494SAl Viro if (!file) 287431e6b01fSNick Piggin return ERR_PTR(-ENFILE); 287531e6b01fSNick Piggin 287630d90494SAl Viro file->f_flags = op->open_flag; 287731e6b01fSNick Piggin 287873d049a4SAl Viro error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base); 287931e6b01fSNick Piggin if (unlikely(error)) 28802675a4ebSAl Viro goto out; 288131e6b01fSNick Piggin 2882fe2d35ffSAl Viro current->total_link_count = 0; 288373d049a4SAl Viro error = link_path_walk(pathname, nd); 288431e6b01fSNick Piggin if (unlikely(error)) 28852675a4ebSAl Viro goto out; 28861da177e4SLinus Torvalds 28872675a4ebSAl Viro error = do_last(nd, &path, file, op, &opened, pathname); 28882675a4ebSAl Viro while (unlikely(error > 0)) { /* trailing symlink */ 28897b9337aaSNick Piggin struct path link = path; 2890def4af30SAl Viro void *cookie; 2891574197e0SAl Viro if (!(nd->flags & LOOKUP_FOLLOW)) { 289273d049a4SAl Viro path_put_conditional(&path, nd); 289373d049a4SAl Viro path_put(&nd->path); 28942675a4ebSAl Viro error = -ELOOP; 289540b39136SAl Viro break; 289640b39136SAl Viro } 2897800179c9SKees Cook error = may_follow_link(&link, nd); 2898800179c9SKees Cook if (unlikely(error)) 2899800179c9SKees Cook break; 290073d049a4SAl Viro nd->flags |= LOOKUP_PARENT; 290173d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 2902574197e0SAl Viro error = follow_link(&link, nd, &cookie); 2903c3e380b0SAl Viro if (unlikely(error)) 29042675a4ebSAl Viro break; 29052675a4ebSAl Viro error = do_last(nd, &path, file, op, &opened, pathname); 2906574197e0SAl Viro put_link(nd, &link, cookie); 2907806b681cSAl Viro } 290810fa8e62SAl Viro out: 290973d049a4SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) 291073d049a4SAl Viro path_put(&nd->root); 2911fe2d35ffSAl Viro if (base) 2912fe2d35ffSAl Viro fput(base); 29132675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 29142675a4ebSAl Viro BUG_ON(!error); 291530d90494SAl Viro put_filp(file); 2916015c3bbcSMiklos Szeredi } 29172675a4ebSAl Viro if (unlikely(error)) { 29182675a4ebSAl Viro if (error == -EOPENSTALE) { 29192675a4ebSAl Viro if (flags & LOOKUP_RCU) 29202675a4ebSAl Viro error = -ECHILD; 29212675a4ebSAl Viro else 29222675a4ebSAl Viro error = -ESTALE; 29232675a4ebSAl Viro } 29242675a4ebSAl Viro file = ERR_PTR(error); 29252675a4ebSAl Viro } 29262675a4ebSAl Viro return file; 2927de459215SKirill Korotaev } 29281da177e4SLinus Torvalds 292913aab428SAl Viro struct file *do_filp_open(int dfd, const char *pathname, 293013aab428SAl Viro const struct open_flags *op, int flags) 293113aab428SAl Viro { 293273d049a4SAl Viro struct nameidata nd; 293313aab428SAl Viro struct file *filp; 293413aab428SAl Viro 293573d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 293613aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 293773d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 293813aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 293973d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 294013aab428SAl Viro return filp; 294113aab428SAl Viro } 294213aab428SAl Viro 294373d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 294473d049a4SAl Viro const char *name, const struct open_flags *op, int flags) 294573d049a4SAl Viro { 294673d049a4SAl Viro struct nameidata nd; 294773d049a4SAl Viro struct file *file; 294873d049a4SAl Viro 294973d049a4SAl Viro nd.root.mnt = mnt; 295073d049a4SAl Viro nd.root.dentry = dentry; 295173d049a4SAl Viro 295273d049a4SAl Viro flags |= LOOKUP_ROOT; 295373d049a4SAl Viro 2954bcda7652SAl Viro if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) 295573d049a4SAl Viro return ERR_PTR(-ELOOP); 295673d049a4SAl Viro 295773d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU); 295873d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 295973d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags); 296073d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 296173d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL); 296273d049a4SAl Viro return file; 296373d049a4SAl Viro } 296473d049a4SAl Viro 2965ed75e95dSAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, int is_dir) 29661da177e4SLinus Torvalds { 2967c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 2968ed75e95dSAl Viro struct nameidata nd; 2969ed75e95dSAl Viro int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd); 2970ed75e95dSAl Viro if (error) 2971ed75e95dSAl Viro return ERR_PTR(error); 29721da177e4SLinus Torvalds 2973c663e5d8SChristoph Hellwig /* 2974c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 2975c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 2976c663e5d8SChristoph Hellwig */ 2977ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 2978ed75e95dSAl Viro goto out; 2979ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 2980ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 2981c663e5d8SChristoph Hellwig 2982c663e5d8SChristoph Hellwig /* 2983c663e5d8SChristoph Hellwig * Do the final lookup. 2984c663e5d8SChristoph Hellwig */ 2985ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 2986ed75e95dSAl Viro dentry = lookup_hash(&nd); 29871da177e4SLinus Torvalds if (IS_ERR(dentry)) 2988a8104a9fSAl Viro goto unlock; 2989c663e5d8SChristoph Hellwig 2990a8104a9fSAl Viro error = -EEXIST; 2991e9baf6e5SAl Viro if (dentry->d_inode) 2992a8104a9fSAl Viro goto fail; 2993c663e5d8SChristoph Hellwig /* 2994c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 2995c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 2996c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 2997c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 2998c663e5d8SChristoph Hellwig */ 2999ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 3000a8104a9fSAl Viro error = -ENOENT; 3001ed75e95dSAl Viro goto fail; 3002e9baf6e5SAl Viro } 3003a8104a9fSAl Viro error = mnt_want_write(nd.path.mnt); 3004a8104a9fSAl Viro if (error) 3005a8104a9fSAl Viro goto fail; 3006ed75e95dSAl Viro *path = nd.path; 3007e9baf6e5SAl Viro return dentry; 30081da177e4SLinus Torvalds fail: 3009a8104a9fSAl Viro dput(dentry); 3010a8104a9fSAl Viro dentry = ERR_PTR(error); 3011a8104a9fSAl Viro unlock: 3012dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3013ed75e95dSAl Viro out: 3014dae6ad8fSAl Viro path_put(&nd.path); 3015ed75e95dSAl Viro return dentry; 3016dae6ad8fSAl Viro } 3017dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3018dae6ad8fSAl Viro 3019921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3020921a1650SAl Viro { 3021921a1650SAl Viro dput(dentry); 3022921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3023a8104a9fSAl Viro mnt_drop_write(path->mnt); 3024921a1650SAl Viro path_put(path); 3025921a1650SAl Viro } 3026921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3027921a1650SAl Viro 3028dae6ad8fSAl Viro struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, int is_dir) 3029dae6ad8fSAl Viro { 3030dae6ad8fSAl Viro char *tmp = getname(pathname); 3031dae6ad8fSAl Viro struct dentry *res; 3032dae6ad8fSAl Viro if (IS_ERR(tmp)) 3033dae6ad8fSAl Viro return ERR_CAST(tmp); 3034dae6ad8fSAl Viro res = kern_path_create(dfd, tmp, path, is_dir); 3035dae6ad8fSAl Viro putname(tmp); 3036dae6ad8fSAl Viro return res; 3037dae6ad8fSAl Viro } 3038dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3039dae6ad8fSAl Viro 30401a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 30411da177e4SLinus Torvalds { 3042a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 30431da177e4SLinus Torvalds 30441da177e4SLinus Torvalds if (error) 30451da177e4SLinus Torvalds return error; 30461da177e4SLinus Torvalds 3047975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 30481da177e4SLinus Torvalds return -EPERM; 30491da177e4SLinus Torvalds 3050acfa4380SAl Viro if (!dir->i_op->mknod) 30511da177e4SLinus Torvalds return -EPERM; 30521da177e4SLinus Torvalds 305308ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 305408ce5f16SSerge E. Hallyn if (error) 305508ce5f16SSerge E. Hallyn return error; 305608ce5f16SSerge E. Hallyn 30571da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 30581da177e4SLinus Torvalds if (error) 30591da177e4SLinus Torvalds return error; 30601da177e4SLinus Torvalds 30611da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3062a74574aaSStephen Smalley if (!error) 3063f38aa942SAmy Griffis fsnotify_create(dir, dentry); 30641da177e4SLinus Torvalds return error; 30651da177e4SLinus Torvalds } 30661da177e4SLinus Torvalds 3067f69aac00SAl Viro static int may_mknod(umode_t mode) 3068463c3197SDave Hansen { 3069463c3197SDave Hansen switch (mode & S_IFMT) { 3070463c3197SDave Hansen case S_IFREG: 3071463c3197SDave Hansen case S_IFCHR: 3072463c3197SDave Hansen case S_IFBLK: 3073463c3197SDave Hansen case S_IFIFO: 3074463c3197SDave Hansen case S_IFSOCK: 3075463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3076463c3197SDave Hansen return 0; 3077463c3197SDave Hansen case S_IFDIR: 3078463c3197SDave Hansen return -EPERM; 3079463c3197SDave Hansen default: 3080463c3197SDave Hansen return -EINVAL; 3081463c3197SDave Hansen } 3082463c3197SDave Hansen } 3083463c3197SDave Hansen 30848208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 30852e4d0924SHeiko Carstens unsigned, dev) 30861da177e4SLinus Torvalds { 30871da177e4SLinus Torvalds struct dentry *dentry; 3088dae6ad8fSAl Viro struct path path; 3089dae6ad8fSAl Viro int error; 30901da177e4SLinus Torvalds 30918e4bfca1SAl Viro error = may_mknod(mode); 30928e4bfca1SAl Viro if (error) 30938e4bfca1SAl Viro return error; 30941da177e4SLinus Torvalds 3095dae6ad8fSAl Viro dentry = user_path_create(dfd, filename, &path, 0); 3096dae6ad8fSAl Viro if (IS_ERR(dentry)) 3097dae6ad8fSAl Viro return PTR_ERR(dentry); 30982ad94ae6SAl Viro 3099dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3100ce3b0f8dSAl Viro mode &= ~current_umask(); 3101dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3102be6d3e56SKentaro Takeda if (error) 3103a8104a9fSAl Viro goto out; 31041da177e4SLinus Torvalds switch (mode & S_IFMT) { 31051da177e4SLinus Torvalds case 0: case S_IFREG: 3106312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 31071da177e4SLinus Torvalds break; 31081da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3109dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 31101da177e4SLinus Torvalds new_decode_dev(dev)); 31111da177e4SLinus Torvalds break; 31121da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3113dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 31141da177e4SLinus Torvalds break; 31151da177e4SLinus Torvalds } 3116a8104a9fSAl Viro out: 3117921a1650SAl Viro done_path_create(&path, dentry); 31181da177e4SLinus Torvalds return error; 31191da177e4SLinus Torvalds } 31201da177e4SLinus Torvalds 31218208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 31225590ff0dSUlrich Drepper { 31235590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 31245590ff0dSUlrich Drepper } 31255590ff0dSUlrich Drepper 312618bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 31271da177e4SLinus Torvalds { 3128a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 31298de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 31301da177e4SLinus Torvalds 31311da177e4SLinus Torvalds if (error) 31321da177e4SLinus Torvalds return error; 31331da177e4SLinus Torvalds 3134acfa4380SAl Viro if (!dir->i_op->mkdir) 31351da177e4SLinus Torvalds return -EPERM; 31361da177e4SLinus Torvalds 31371da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 31381da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 31391da177e4SLinus Torvalds if (error) 31401da177e4SLinus Torvalds return error; 31411da177e4SLinus Torvalds 31428de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 31438de52778SAl Viro return -EMLINK; 31448de52778SAl Viro 31451da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3146a74574aaSStephen Smalley if (!error) 3147f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 31481da177e4SLinus Torvalds return error; 31491da177e4SLinus Torvalds } 31501da177e4SLinus Torvalds 3151a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 31521da177e4SLinus Torvalds { 31536902d925SDave Hansen struct dentry *dentry; 3154dae6ad8fSAl Viro struct path path; 3155dae6ad8fSAl Viro int error; 31561da177e4SLinus Torvalds 3157dae6ad8fSAl Viro dentry = user_path_create(dfd, pathname, &path, 1); 31586902d925SDave Hansen if (IS_ERR(dentry)) 3159dae6ad8fSAl Viro return PTR_ERR(dentry); 31606902d925SDave Hansen 3161dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3162ce3b0f8dSAl Viro mode &= ~current_umask(); 3163dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3164a8104a9fSAl Viro if (!error) 3165dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3166921a1650SAl Viro done_path_create(&path, dentry); 31671da177e4SLinus Torvalds return error; 31681da177e4SLinus Torvalds } 31691da177e4SLinus Torvalds 3170a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 31715590ff0dSUlrich Drepper { 31725590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 31735590ff0dSUlrich Drepper } 31745590ff0dSUlrich Drepper 31751da177e4SLinus Torvalds /* 3176a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3177c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3178a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3179a71905f0SSage Weil * then we drop the dentry now. 31801da177e4SLinus Torvalds * 31811da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 31821da177e4SLinus Torvalds * do a 31831da177e4SLinus Torvalds * 31841da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 31851da177e4SLinus Torvalds * return -EBUSY; 31861da177e4SLinus Torvalds * 31871da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 31881da177e4SLinus Torvalds * that is still in use by something else.. 31891da177e4SLinus Torvalds */ 31901da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 31911da177e4SLinus Torvalds { 31921da177e4SLinus Torvalds shrink_dcache_parent(dentry); 31931da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 319464252c75SSage Weil if (dentry->d_count == 1) 31951da177e4SLinus Torvalds __d_drop(dentry); 31961da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 31971da177e4SLinus Torvalds } 31981da177e4SLinus Torvalds 31991da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 32001da177e4SLinus Torvalds { 32011da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 32021da177e4SLinus Torvalds 32031da177e4SLinus Torvalds if (error) 32041da177e4SLinus Torvalds return error; 32051da177e4SLinus Torvalds 3206acfa4380SAl Viro if (!dir->i_op->rmdir) 32071da177e4SLinus Torvalds return -EPERM; 32081da177e4SLinus Torvalds 32091d2ef590SAl Viro dget(dentry); 32101b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3211912dbc15SSage Weil 32121da177e4SLinus Torvalds error = -EBUSY; 3213912dbc15SSage Weil if (d_mountpoint(dentry)) 3214912dbc15SSage Weil goto out; 3215912dbc15SSage Weil 32161da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3217912dbc15SSage Weil if (error) 3218912dbc15SSage Weil goto out; 3219912dbc15SSage Weil 32203cebde24SSage Weil shrink_dcache_parent(dentry); 32211da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3222912dbc15SSage Weil if (error) 3223912dbc15SSage Weil goto out; 3224912dbc15SSage Weil 32251da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3226d83c49f3SAl Viro dont_mount(dentry); 32271da177e4SLinus Torvalds 3228912dbc15SSage Weil out: 3229912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 32301d2ef590SAl Viro dput(dentry); 3231912dbc15SSage Weil if (!error) 3232912dbc15SSage Weil d_delete(dentry); 32331da177e4SLinus Torvalds return error; 32341da177e4SLinus Torvalds } 32351da177e4SLinus Torvalds 32365590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 32371da177e4SLinus Torvalds { 32381da177e4SLinus Torvalds int error = 0; 32391da177e4SLinus Torvalds char * name; 32401da177e4SLinus Torvalds struct dentry *dentry; 32411da177e4SLinus Torvalds struct nameidata nd; 32421da177e4SLinus Torvalds 32432ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 32441da177e4SLinus Torvalds if (error) 32452ad94ae6SAl Viro return error; 32461da177e4SLinus Torvalds 32471da177e4SLinus Torvalds switch(nd.last_type) { 32481da177e4SLinus Torvalds case LAST_DOTDOT: 32491da177e4SLinus Torvalds error = -ENOTEMPTY; 32501da177e4SLinus Torvalds goto exit1; 32511da177e4SLinus Torvalds case LAST_DOT: 32521da177e4SLinus Torvalds error = -EINVAL; 32531da177e4SLinus Torvalds goto exit1; 32541da177e4SLinus Torvalds case LAST_ROOT: 32551da177e4SLinus Torvalds error = -EBUSY; 32561da177e4SLinus Torvalds goto exit1; 32571da177e4SLinus Torvalds } 32580612d9fbSOGAWA Hirofumi 32590612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 32600612d9fbSOGAWA Hirofumi 32614ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 326249705b77SChristoph Hellwig dentry = lookup_hash(&nd); 32631da177e4SLinus Torvalds error = PTR_ERR(dentry); 32646902d925SDave Hansen if (IS_ERR(dentry)) 32656902d925SDave Hansen goto exit2; 3266e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3267e6bc45d6STheodore Ts'o error = -ENOENT; 3268e6bc45d6STheodore Ts'o goto exit3; 3269e6bc45d6STheodore Ts'o } 32700622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 32710622753bSDave Hansen if (error) 32720622753bSDave Hansen goto exit3; 3273be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 3274be6d3e56SKentaro Takeda if (error) 3275be6d3e56SKentaro Takeda goto exit4; 32764ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 3277be6d3e56SKentaro Takeda exit4: 32780622753bSDave Hansen mnt_drop_write(nd.path.mnt); 32790622753bSDave Hansen exit3: 32801da177e4SLinus Torvalds dput(dentry); 32816902d925SDave Hansen exit2: 32824ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 32831da177e4SLinus Torvalds exit1: 32841d957f9bSJan Blunck path_put(&nd.path); 32851da177e4SLinus Torvalds putname(name); 32861da177e4SLinus Torvalds return error; 32871da177e4SLinus Torvalds } 32881da177e4SLinus Torvalds 32893cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 32905590ff0dSUlrich Drepper { 32915590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 32925590ff0dSUlrich Drepper } 32935590ff0dSUlrich Drepper 32941da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 32951da177e4SLinus Torvalds { 32961da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 32971da177e4SLinus Torvalds 32981da177e4SLinus Torvalds if (error) 32991da177e4SLinus Torvalds return error; 33001da177e4SLinus Torvalds 3301acfa4380SAl Viro if (!dir->i_op->unlink) 33021da177e4SLinus Torvalds return -EPERM; 33031da177e4SLinus Torvalds 33041b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 33051da177e4SLinus Torvalds if (d_mountpoint(dentry)) 33061da177e4SLinus Torvalds error = -EBUSY; 33071da177e4SLinus Torvalds else { 33081da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3309bec1052eSAl Viro if (!error) { 33101da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 3311bec1052eSAl Viro if (!error) 3312d83c49f3SAl Viro dont_mount(dentry); 3313bec1052eSAl Viro } 33141da177e4SLinus Torvalds } 33151b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 33161da177e4SLinus Torvalds 33171da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 33181da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 3319ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 33201da177e4SLinus Torvalds d_delete(dentry); 33211da177e4SLinus Torvalds } 33220eeca283SRobert Love 33231da177e4SLinus Torvalds return error; 33241da177e4SLinus Torvalds } 33251da177e4SLinus Torvalds 33261da177e4SLinus Torvalds /* 33271da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 33281b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 33291da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 33301da177e4SLinus Torvalds * while waiting on the I/O. 33311da177e4SLinus Torvalds */ 33325590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 33331da177e4SLinus Torvalds { 33342ad94ae6SAl Viro int error; 33351da177e4SLinus Torvalds char *name; 33361da177e4SLinus Torvalds struct dentry *dentry; 33371da177e4SLinus Torvalds struct nameidata nd; 33381da177e4SLinus Torvalds struct inode *inode = NULL; 33391da177e4SLinus Torvalds 33402ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 33411da177e4SLinus Torvalds if (error) 33422ad94ae6SAl Viro return error; 33432ad94ae6SAl Viro 33441da177e4SLinus Torvalds error = -EISDIR; 33451da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 33461da177e4SLinus Torvalds goto exit1; 33470612d9fbSOGAWA Hirofumi 33480612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 33490612d9fbSOGAWA Hirofumi 33504ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 335149705b77SChristoph Hellwig dentry = lookup_hash(&nd); 33521da177e4SLinus Torvalds error = PTR_ERR(dentry); 33531da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 33541da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 335550338b88STörök Edwin if (nd.last.name[nd.last.len]) 335650338b88STörök Edwin goto slashes; 33571da177e4SLinus Torvalds inode = dentry->d_inode; 335850338b88STörök Edwin if (!inode) 3359e6bc45d6STheodore Ts'o goto slashes; 33607de9c6eeSAl Viro ihold(inode); 33610622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 33620622753bSDave Hansen if (error) 33630622753bSDave Hansen goto exit2; 3364be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 3365be6d3e56SKentaro Takeda if (error) 3366be6d3e56SKentaro Takeda goto exit3; 33674ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 3368be6d3e56SKentaro Takeda exit3: 33690622753bSDave Hansen mnt_drop_write(nd.path.mnt); 33701da177e4SLinus Torvalds exit2: 33711da177e4SLinus Torvalds dput(dentry); 33721da177e4SLinus Torvalds } 33734ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 33741da177e4SLinus Torvalds if (inode) 33751da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 33761da177e4SLinus Torvalds exit1: 33771d957f9bSJan Blunck path_put(&nd.path); 33781da177e4SLinus Torvalds putname(name); 33791da177e4SLinus Torvalds return error; 33801da177e4SLinus Torvalds 33811da177e4SLinus Torvalds slashes: 33821da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 33831da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 33841da177e4SLinus Torvalds goto exit2; 33851da177e4SLinus Torvalds } 33861da177e4SLinus Torvalds 33872e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 33885590ff0dSUlrich Drepper { 33895590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 33905590ff0dSUlrich Drepper return -EINVAL; 33915590ff0dSUlrich Drepper 33925590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 33935590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 33945590ff0dSUlrich Drepper 33955590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 33965590ff0dSUlrich Drepper } 33975590ff0dSUlrich Drepper 33983480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 33995590ff0dSUlrich Drepper { 34005590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 34015590ff0dSUlrich Drepper } 34025590ff0dSUlrich Drepper 3403db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 34041da177e4SLinus Torvalds { 3405a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 34061da177e4SLinus Torvalds 34071da177e4SLinus Torvalds if (error) 34081da177e4SLinus Torvalds return error; 34091da177e4SLinus Torvalds 3410acfa4380SAl Viro if (!dir->i_op->symlink) 34111da177e4SLinus Torvalds return -EPERM; 34121da177e4SLinus Torvalds 34131da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 34141da177e4SLinus Torvalds if (error) 34151da177e4SLinus Torvalds return error; 34161da177e4SLinus Torvalds 34171da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3418a74574aaSStephen Smalley if (!error) 3419f38aa942SAmy Griffis fsnotify_create(dir, dentry); 34201da177e4SLinus Torvalds return error; 34211da177e4SLinus Torvalds } 34221da177e4SLinus Torvalds 34232e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 34242e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 34251da177e4SLinus Torvalds { 34262ad94ae6SAl Viro int error; 34271da177e4SLinus Torvalds char *from; 34286902d925SDave Hansen struct dentry *dentry; 3429dae6ad8fSAl Viro struct path path; 34301da177e4SLinus Torvalds 34311da177e4SLinus Torvalds from = getname(oldname); 34321da177e4SLinus Torvalds if (IS_ERR(from)) 34331da177e4SLinus Torvalds return PTR_ERR(from); 34342ad94ae6SAl Viro 3435dae6ad8fSAl Viro dentry = user_path_create(newdfd, newname, &path, 0); 34361da177e4SLinus Torvalds error = PTR_ERR(dentry); 34376902d925SDave Hansen if (IS_ERR(dentry)) 3438dae6ad8fSAl Viro goto out_putname; 34396902d925SDave Hansen 3440dae6ad8fSAl Viro error = security_path_symlink(&path, dentry, from); 3441a8104a9fSAl Viro if (!error) 3442dae6ad8fSAl Viro error = vfs_symlink(path.dentry->d_inode, dentry, from); 3443921a1650SAl Viro done_path_create(&path, dentry); 34446902d925SDave Hansen out_putname: 34451da177e4SLinus Torvalds putname(from); 34461da177e4SLinus Torvalds return error; 34471da177e4SLinus Torvalds } 34481da177e4SLinus Torvalds 34493480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 34505590ff0dSUlrich Drepper { 34515590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 34525590ff0dSUlrich Drepper } 34535590ff0dSUlrich Drepper 34541da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 34551da177e4SLinus Torvalds { 34561da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 34578de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 34581da177e4SLinus Torvalds int error; 34591da177e4SLinus Torvalds 34601da177e4SLinus Torvalds if (!inode) 34611da177e4SLinus Torvalds return -ENOENT; 34621da177e4SLinus Torvalds 3463a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 34641da177e4SLinus Torvalds if (error) 34651da177e4SLinus Torvalds return error; 34661da177e4SLinus Torvalds 34671da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 34681da177e4SLinus Torvalds return -EXDEV; 34691da177e4SLinus Torvalds 34701da177e4SLinus Torvalds /* 34711da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 34721da177e4SLinus Torvalds */ 34731da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 34741da177e4SLinus Torvalds return -EPERM; 3475acfa4380SAl Viro if (!dir->i_op->link) 34761da177e4SLinus Torvalds return -EPERM; 34777e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 34781da177e4SLinus Torvalds return -EPERM; 34791da177e4SLinus Torvalds 34801da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 34811da177e4SLinus Torvalds if (error) 34821da177e4SLinus Torvalds return error; 34831da177e4SLinus Torvalds 34847e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 3485aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 3486aae8a97dSAneesh Kumar K.V if (inode->i_nlink == 0) 3487aae8a97dSAneesh Kumar K.V error = -ENOENT; 34888de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 34898de52778SAl Viro error = -EMLINK; 3490aae8a97dSAneesh Kumar K.V else 34911da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 34927e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 3493e31e14ecSStephen Smalley if (!error) 34947e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 34951da177e4SLinus Torvalds return error; 34961da177e4SLinus Torvalds } 34971da177e4SLinus Torvalds 34981da177e4SLinus Torvalds /* 34991da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 35001da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 35011da177e4SLinus Torvalds * newname. --KAB 35021da177e4SLinus Torvalds * 35031da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 35041da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 35051da177e4SLinus Torvalds * and other special files. --ADM 35061da177e4SLinus Torvalds */ 35072e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 35082e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 35091da177e4SLinus Torvalds { 35101da177e4SLinus Torvalds struct dentry *new_dentry; 3511dae6ad8fSAl Viro struct path old_path, new_path; 351211a7b371SAneesh Kumar K.V int how = 0; 35131da177e4SLinus Torvalds int error; 35141da177e4SLinus Torvalds 351511a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 3516c04030e1SUlrich Drepper return -EINVAL; 351711a7b371SAneesh Kumar K.V /* 351811a7b371SAneesh Kumar K.V * To use null names we require CAP_DAC_READ_SEARCH 351911a7b371SAneesh Kumar K.V * This ensures that not everyone will be able to create 352011a7b371SAneesh Kumar K.V * handlink using the passed filedescriptor. 352111a7b371SAneesh Kumar K.V */ 352211a7b371SAneesh Kumar K.V if (flags & AT_EMPTY_PATH) { 352311a7b371SAneesh Kumar K.V if (!capable(CAP_DAC_READ_SEARCH)) 352411a7b371SAneesh Kumar K.V return -ENOENT; 352511a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 352611a7b371SAneesh Kumar K.V } 3527c04030e1SUlrich Drepper 352811a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 352911a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 353011a7b371SAneesh Kumar K.V 353111a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 35321da177e4SLinus Torvalds if (error) 35332ad94ae6SAl Viro return error; 35342ad94ae6SAl Viro 3535dae6ad8fSAl Viro new_dentry = user_path_create(newdfd, newname, &new_path, 0); 35361da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 35376902d925SDave Hansen if (IS_ERR(new_dentry)) 3538dae6ad8fSAl Viro goto out; 3539dae6ad8fSAl Viro 3540dae6ad8fSAl Viro error = -EXDEV; 3541dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 3542dae6ad8fSAl Viro goto out_dput; 3543800179c9SKees Cook error = may_linkat(&old_path); 3544800179c9SKees Cook if (unlikely(error)) 3545800179c9SKees Cook goto out_dput; 3546dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 3547be6d3e56SKentaro Takeda if (error) 3548a8104a9fSAl Viro goto out_dput; 3549dae6ad8fSAl Viro error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry); 355075c3f29dSDave Hansen out_dput: 3551921a1650SAl Viro done_path_create(&new_path, new_dentry); 35521da177e4SLinus Torvalds out: 35532d8f3038SAl Viro path_put(&old_path); 35541da177e4SLinus Torvalds 35551da177e4SLinus Torvalds return error; 35561da177e4SLinus Torvalds } 35571da177e4SLinus Torvalds 35583480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 35595590ff0dSUlrich Drepper { 3560c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 35615590ff0dSUlrich Drepper } 35625590ff0dSUlrich Drepper 35631da177e4SLinus Torvalds /* 35641da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 35651da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 35661da177e4SLinus Torvalds * Problems: 35671da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 35681da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 35691da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 3570a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 35711da177e4SLinus Torvalds * story. 35721da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 35731b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 35741da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 35751da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 3576a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 35771da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 35781da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 35791da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 3580a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 35811da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 35821da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 35831da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 3584e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 35851b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 35861da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 3587c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 35881da177e4SLinus Torvalds * locking]. 35891da177e4SLinus Torvalds */ 359075c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 35911da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 35921da177e4SLinus Torvalds { 35931da177e4SLinus Torvalds int error = 0; 35949055cba7SSage Weil struct inode *target = new_dentry->d_inode; 35958de52778SAl Viro unsigned max_links = new_dir->i_sb->s_max_links; 35961da177e4SLinus Torvalds 35971da177e4SLinus Torvalds /* 35981da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 35991da177e4SLinus Torvalds * we'll need to flip '..'. 36001da177e4SLinus Torvalds */ 36011da177e4SLinus Torvalds if (new_dir != old_dir) { 3602f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 36031da177e4SLinus Torvalds if (error) 36041da177e4SLinus Torvalds return error; 36051da177e4SLinus Torvalds } 36061da177e4SLinus Torvalds 36071da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 36081da177e4SLinus Torvalds if (error) 36091da177e4SLinus Torvalds return error; 36101da177e4SLinus Torvalds 36111d2ef590SAl Viro dget(new_dentry); 3612d83c49f3SAl Viro if (target) 36131b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 36149055cba7SSage Weil 36151da177e4SLinus Torvalds error = -EBUSY; 36169055cba7SSage Weil if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) 36179055cba7SSage Weil goto out; 36189055cba7SSage Weil 36198de52778SAl Viro error = -EMLINK; 36208de52778SAl Viro if (max_links && !target && new_dir != old_dir && 36218de52778SAl Viro new_dir->i_nlink >= max_links) 36228de52778SAl Viro goto out; 36238de52778SAl Viro 36243cebde24SSage Weil if (target) 36253cebde24SSage Weil shrink_dcache_parent(new_dentry); 36261da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 36279055cba7SSage Weil if (error) 36289055cba7SSage Weil goto out; 36299055cba7SSage Weil 36301da177e4SLinus Torvalds if (target) { 36311da177e4SLinus Torvalds target->i_flags |= S_DEAD; 3632d83c49f3SAl Viro dont_mount(new_dentry); 3633d83c49f3SAl Viro } 36349055cba7SSage Weil out: 36359055cba7SSage Weil if (target) 36361b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 36371d2ef590SAl Viro dput(new_dentry); 3638e31e14ecSStephen Smalley if (!error) 3639349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 36401da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 36411da177e4SLinus Torvalds return error; 36421da177e4SLinus Torvalds } 36431da177e4SLinus Torvalds 364475c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 36451da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 36461da177e4SLinus Torvalds { 364751892bbbSSage Weil struct inode *target = new_dentry->d_inode; 36481da177e4SLinus Torvalds int error; 36491da177e4SLinus Torvalds 36501da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 36511da177e4SLinus Torvalds if (error) 36521da177e4SLinus Torvalds return error; 36531da177e4SLinus Torvalds 36541da177e4SLinus Torvalds dget(new_dentry); 36551da177e4SLinus Torvalds if (target) 36561b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 365751892bbbSSage Weil 36581da177e4SLinus Torvalds error = -EBUSY; 365951892bbbSSage Weil if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 366051892bbbSSage Weil goto out; 366151892bbbSSage Weil 36621da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 366351892bbbSSage Weil if (error) 366451892bbbSSage Weil goto out; 366551892bbbSSage Weil 3666bec1052eSAl Viro if (target) 3667d83c49f3SAl Viro dont_mount(new_dentry); 3668349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 36691da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 367051892bbbSSage Weil out: 36711da177e4SLinus Torvalds if (target) 36721b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 36731da177e4SLinus Torvalds dput(new_dentry); 36741da177e4SLinus Torvalds return error; 36751da177e4SLinus Torvalds } 36761da177e4SLinus Torvalds 36771da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 36781da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 36791da177e4SLinus Torvalds { 36801da177e4SLinus Torvalds int error; 36811da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 368259b0df21SEric Paris const unsigned char *old_name; 36831da177e4SLinus Torvalds 36841da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 36851da177e4SLinus Torvalds return 0; 36861da177e4SLinus Torvalds 36871da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 36881da177e4SLinus Torvalds if (error) 36891da177e4SLinus Torvalds return error; 36901da177e4SLinus Torvalds 36911da177e4SLinus Torvalds if (!new_dentry->d_inode) 3692a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 36931da177e4SLinus Torvalds else 36941da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 36951da177e4SLinus Torvalds if (error) 36961da177e4SLinus Torvalds return error; 36971da177e4SLinus Torvalds 3698acfa4380SAl Viro if (!old_dir->i_op->rename) 36991da177e4SLinus Torvalds return -EPERM; 37001da177e4SLinus Torvalds 37010eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 37020eeca283SRobert Love 37031da177e4SLinus Torvalds if (is_dir) 37041da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 37051da177e4SLinus Torvalds else 37061da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 3707123df294SAl Viro if (!error) 3708123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 37095a190ae6SAl Viro new_dentry->d_inode, old_dentry); 37100eeca283SRobert Love fsnotify_oldname_free(old_name); 37110eeca283SRobert Love 37121da177e4SLinus Torvalds return error; 37131da177e4SLinus Torvalds } 37141da177e4SLinus Torvalds 37152e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 37162e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 37171da177e4SLinus Torvalds { 37181da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 37191da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 37201da177e4SLinus Torvalds struct dentry *trap; 37211da177e4SLinus Torvalds struct nameidata oldnd, newnd; 37222ad94ae6SAl Viro char *from; 37232ad94ae6SAl Viro char *to; 37242ad94ae6SAl Viro int error; 37251da177e4SLinus Torvalds 37262ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 37271da177e4SLinus Torvalds if (error) 37281da177e4SLinus Torvalds goto exit; 37291da177e4SLinus Torvalds 37302ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 37311da177e4SLinus Torvalds if (error) 37321da177e4SLinus Torvalds goto exit1; 37331da177e4SLinus Torvalds 37341da177e4SLinus Torvalds error = -EXDEV; 37354ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 37361da177e4SLinus Torvalds goto exit2; 37371da177e4SLinus Torvalds 37384ac91378SJan Blunck old_dir = oldnd.path.dentry; 37391da177e4SLinus Torvalds error = -EBUSY; 37401da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 37411da177e4SLinus Torvalds goto exit2; 37421da177e4SLinus Torvalds 37434ac91378SJan Blunck new_dir = newnd.path.dentry; 37441da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 37451da177e4SLinus Torvalds goto exit2; 37461da177e4SLinus Torvalds 37470612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 37480612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 37494e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 37500612d9fbSOGAWA Hirofumi 37511da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 37521da177e4SLinus Torvalds 375349705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 37541da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 37551da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 37561da177e4SLinus Torvalds goto exit3; 37571da177e4SLinus Torvalds /* source must exist */ 37581da177e4SLinus Torvalds error = -ENOENT; 37591da177e4SLinus Torvalds if (!old_dentry->d_inode) 37601da177e4SLinus Torvalds goto exit4; 37611da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 37621da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 37631da177e4SLinus Torvalds error = -ENOTDIR; 37641da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 37651da177e4SLinus Torvalds goto exit4; 37661da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 37671da177e4SLinus Torvalds goto exit4; 37681da177e4SLinus Torvalds } 37691da177e4SLinus Torvalds /* source should not be ancestor of target */ 37701da177e4SLinus Torvalds error = -EINVAL; 37711da177e4SLinus Torvalds if (old_dentry == trap) 37721da177e4SLinus Torvalds goto exit4; 377349705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 37741da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 37751da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 37761da177e4SLinus Torvalds goto exit4; 37771da177e4SLinus Torvalds /* target should not be an ancestor of source */ 37781da177e4SLinus Torvalds error = -ENOTEMPTY; 37791da177e4SLinus Torvalds if (new_dentry == trap) 37801da177e4SLinus Torvalds goto exit5; 37811da177e4SLinus Torvalds 37829079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 37839079b1ebSDave Hansen if (error) 37849079b1ebSDave Hansen goto exit5; 3785be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 3786be6d3e56SKentaro Takeda &newnd.path, new_dentry); 3787be6d3e56SKentaro Takeda if (error) 3788be6d3e56SKentaro Takeda goto exit6; 37891da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 37901da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 3791be6d3e56SKentaro Takeda exit6: 37929079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 37931da177e4SLinus Torvalds exit5: 37941da177e4SLinus Torvalds dput(new_dentry); 37951da177e4SLinus Torvalds exit4: 37961da177e4SLinus Torvalds dput(old_dentry); 37971da177e4SLinus Torvalds exit3: 37981da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 37991da177e4SLinus Torvalds exit2: 38001d957f9bSJan Blunck path_put(&newnd.path); 38012ad94ae6SAl Viro putname(to); 38021da177e4SLinus Torvalds exit1: 38031d957f9bSJan Blunck path_put(&oldnd.path); 38041da177e4SLinus Torvalds putname(from); 38052ad94ae6SAl Viro exit: 38061da177e4SLinus Torvalds return error; 38071da177e4SLinus Torvalds } 38081da177e4SLinus Torvalds 3809a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 38105590ff0dSUlrich Drepper { 38115590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 38125590ff0dSUlrich Drepper } 38135590ff0dSUlrich Drepper 38141da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 38151da177e4SLinus Torvalds { 38161da177e4SLinus Torvalds int len; 38171da177e4SLinus Torvalds 38181da177e4SLinus Torvalds len = PTR_ERR(link); 38191da177e4SLinus Torvalds if (IS_ERR(link)) 38201da177e4SLinus Torvalds goto out; 38211da177e4SLinus Torvalds 38221da177e4SLinus Torvalds len = strlen(link); 38231da177e4SLinus Torvalds if (len > (unsigned) buflen) 38241da177e4SLinus Torvalds len = buflen; 38251da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 38261da177e4SLinus Torvalds len = -EFAULT; 38271da177e4SLinus Torvalds out: 38281da177e4SLinus Torvalds return len; 38291da177e4SLinus Torvalds } 38301da177e4SLinus Torvalds 38311da177e4SLinus Torvalds /* 38321da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 38331da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 38341da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 38351da177e4SLinus Torvalds */ 38361da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 38371da177e4SLinus Torvalds { 38381da177e4SLinus Torvalds struct nameidata nd; 3839cc314eefSLinus Torvalds void *cookie; 3840694a1764SMarcin Slusarz int res; 3841cc314eefSLinus Torvalds 38421da177e4SLinus Torvalds nd.depth = 0; 3843cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 3844694a1764SMarcin Slusarz if (IS_ERR(cookie)) 3845694a1764SMarcin Slusarz return PTR_ERR(cookie); 3846694a1764SMarcin Slusarz 3847694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 38481da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 3849cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 3850694a1764SMarcin Slusarz return res; 38511da177e4SLinus Torvalds } 38521da177e4SLinus Torvalds 38531da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 38541da177e4SLinus Torvalds { 38551da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 38561da177e4SLinus Torvalds } 38571da177e4SLinus Torvalds 38581da177e4SLinus Torvalds /* get the link contents into pagecache */ 38591da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 38601da177e4SLinus Torvalds { 3861ebd09abbSDuane Griffin char *kaddr; 38621da177e4SLinus Torvalds struct page *page; 38631da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 3864090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 38651da177e4SLinus Torvalds if (IS_ERR(page)) 38666fe6900eSNick Piggin return (char*)page; 38671da177e4SLinus Torvalds *ppage = page; 3868ebd09abbSDuane Griffin kaddr = kmap(page); 3869ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 3870ebd09abbSDuane Griffin return kaddr; 38711da177e4SLinus Torvalds } 38721da177e4SLinus Torvalds 38731da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 38741da177e4SLinus Torvalds { 38751da177e4SLinus Torvalds struct page *page = NULL; 38761da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 38771da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 38781da177e4SLinus Torvalds if (page) { 38791da177e4SLinus Torvalds kunmap(page); 38801da177e4SLinus Torvalds page_cache_release(page); 38811da177e4SLinus Torvalds } 38821da177e4SLinus Torvalds return res; 38831da177e4SLinus Torvalds } 38841da177e4SLinus Torvalds 3885cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 38861da177e4SLinus Torvalds { 3887cc314eefSLinus Torvalds struct page *page = NULL; 38881da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 3889cc314eefSLinus Torvalds return page; 38901da177e4SLinus Torvalds } 38911da177e4SLinus Torvalds 3892cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 38931da177e4SLinus Torvalds { 3894cc314eefSLinus Torvalds struct page *page = cookie; 3895cc314eefSLinus Torvalds 3896cc314eefSLinus Torvalds if (page) { 38971da177e4SLinus Torvalds kunmap(page); 38981da177e4SLinus Torvalds page_cache_release(page); 38991da177e4SLinus Torvalds } 39001da177e4SLinus Torvalds } 39011da177e4SLinus Torvalds 390254566b2cSNick Piggin /* 390354566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 390454566b2cSNick Piggin */ 390554566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 39061da177e4SLinus Torvalds { 39071da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 39080adb25d2SKirill Korotaev struct page *page; 3909afddba49SNick Piggin void *fsdata; 3910beb497abSDmitriy Monakhov int err; 39111da177e4SLinus Torvalds char *kaddr; 391254566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 391354566b2cSNick Piggin if (nofs) 391454566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 39151da177e4SLinus Torvalds 39167e53cac4SNeilBrown retry: 3917afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 391854566b2cSNick Piggin flags, &page, &fsdata); 39191da177e4SLinus Torvalds if (err) 3920afddba49SNick Piggin goto fail; 3921afddba49SNick Piggin 3922e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 39231da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 3924e8e3c3d6SCong Wang kunmap_atomic(kaddr); 3925afddba49SNick Piggin 3926afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 3927afddba49SNick Piggin page, fsdata); 39281da177e4SLinus Torvalds if (err < 0) 39291da177e4SLinus Torvalds goto fail; 3930afddba49SNick Piggin if (err < len-1) 3931afddba49SNick Piggin goto retry; 3932afddba49SNick Piggin 39331da177e4SLinus Torvalds mark_inode_dirty(inode); 39341da177e4SLinus Torvalds return 0; 39351da177e4SLinus Torvalds fail: 39361da177e4SLinus Torvalds return err; 39371da177e4SLinus Torvalds } 39381da177e4SLinus Torvalds 39390adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 39400adb25d2SKirill Korotaev { 39410adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 394254566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 39430adb25d2SKirill Korotaev } 39440adb25d2SKirill Korotaev 394592e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 39461da177e4SLinus Torvalds .readlink = generic_readlink, 39471da177e4SLinus Torvalds .follow_link = page_follow_link_light, 39481da177e4SLinus Torvalds .put_link = page_put_link, 39491da177e4SLinus Torvalds }; 39501da177e4SLinus Torvalds 39512d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 3952cc53ce53SDavid Howells EXPORT_SYMBOL(follow_down_one); 39531da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 39541da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 39551da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 39561da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 39571da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 39581da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 39591da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 39601da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 39611da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 39620adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 39631da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 39641da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 3965d1811465SAl Viro EXPORT_SYMBOL(kern_path); 396616f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 3967f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 39681da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 39691da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 39701da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 39711da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 39721da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 39731da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 39741da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 39751da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 39761da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 39771da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 39781da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 39791da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 39801da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 39811da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 3982