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 653def4af30SAl Viro static __always_inline int 654574197e0SAl Viro follow_link(struct path *link, struct nameidata *nd, void **p) 6551da177e4SLinus Torvalds { 6567b9337aaSNick Piggin struct dentry *dentry = link->dentry; 6576d7b5aaeSAl Viro int error; 6586d7b5aaeSAl Viro char *s; 6591da177e4SLinus Torvalds 660844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 661844a3917SAl Viro 6620e794589SAl Viro if (link->mnt == nd->path.mnt) 6630e794589SAl Viro mntget(link->mnt); 6640e794589SAl Viro 6656d7b5aaeSAl Viro error = -ELOOP; 6666d7b5aaeSAl Viro if (unlikely(current->total_link_count >= 40)) 6676d7b5aaeSAl Viro goto out_put_nd_path; 6686d7b5aaeSAl Viro 669574197e0SAl Viro cond_resched(); 670574197e0SAl Viro current->total_link_count++; 671574197e0SAl Viro 67268ac1234SAl Viro touch_atime(link); 6731da177e4SLinus Torvalds nd_set_link(nd, NULL); 674cd4e91d3SAl Viro 67536f3b4f6SAl Viro error = security_inode_follow_link(link->dentry, nd); 6766d7b5aaeSAl Viro if (error) 6776d7b5aaeSAl Viro goto out_put_nd_path; 67836f3b4f6SAl Viro 67986acdca1SAl Viro nd->last_type = LAST_BIND; 680def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 681def4af30SAl Viro error = PTR_ERR(*p); 6826d7b5aaeSAl Viro if (IS_ERR(*p)) 683408ef013SChristoph Hellwig goto out_put_nd_path; 6846d7b5aaeSAl Viro 685cc314eefSLinus Torvalds error = 0; 6866d7b5aaeSAl Viro s = nd_get_link(nd); 6876d7b5aaeSAl Viro if (s) { 6881da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 6896d7b5aaeSAl Viro if (unlikely(error)) 6906d7b5aaeSAl Viro put_link(nd, link, *p); 691b5fb63c1SChristoph Hellwig } 6926d7b5aaeSAl Viro 6936d7b5aaeSAl Viro return error; 6946d7b5aaeSAl Viro 6956d7b5aaeSAl Viro out_put_nd_path: 6966d7b5aaeSAl Viro path_put(&nd->path); 6976d7b5aaeSAl Viro path_put(link); 6981da177e4SLinus Torvalds return error; 6991da177e4SLinus Torvalds } 7001da177e4SLinus Torvalds 70131e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 70231e6b01fSNick Piggin { 7030714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 7040714a533SAl Viro struct mount *parent; 70531e6b01fSNick Piggin struct dentry *mountpoint; 70631e6b01fSNick Piggin 7070714a533SAl Viro parent = mnt->mnt_parent; 7080714a533SAl Viro if (&parent->mnt == path->mnt) 70931e6b01fSNick Piggin return 0; 710a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 71131e6b01fSNick Piggin path->dentry = mountpoint; 7120714a533SAl Viro path->mnt = &parent->mnt; 71331e6b01fSNick Piggin return 1; 71431e6b01fSNick Piggin } 71531e6b01fSNick Piggin 716f015f126SDavid Howells /* 717f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 718f015f126SDavid Howells * 719f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 720f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 721f015f126SDavid Howells * Up is towards /. 722f015f126SDavid Howells * 723f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 724f015f126SDavid Howells * root. 725f015f126SDavid Howells */ 726bab77ebfSAl Viro int follow_up(struct path *path) 7271da177e4SLinus Torvalds { 7280714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 7290714a533SAl Viro struct mount *parent; 7301da177e4SLinus Torvalds struct dentry *mountpoint; 73199b7db7bSNick Piggin 732962830dfSAndi Kleen br_read_lock(&vfsmount_lock); 7330714a533SAl Viro parent = mnt->mnt_parent; 7343c0a6163SAl Viro if (parent == mnt) { 735962830dfSAndi Kleen br_read_unlock(&vfsmount_lock); 7361da177e4SLinus Torvalds return 0; 7371da177e4SLinus Torvalds } 7380714a533SAl Viro mntget(&parent->mnt); 739a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 740962830dfSAndi Kleen br_read_unlock(&vfsmount_lock); 741bab77ebfSAl Viro dput(path->dentry); 742bab77ebfSAl Viro path->dentry = mountpoint; 743bab77ebfSAl Viro mntput(path->mnt); 7440714a533SAl Viro path->mnt = &parent->mnt; 7451da177e4SLinus Torvalds return 1; 7461da177e4SLinus Torvalds } 7471da177e4SLinus Torvalds 748b5c84bf6SNick Piggin /* 7499875cf80SDavid Howells * Perform an automount 7509875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 7519875cf80SDavid Howells * were called with. 7521da177e4SLinus Torvalds */ 7539875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 7549875cf80SDavid Howells bool *need_mntput) 75531e6b01fSNick Piggin { 7569875cf80SDavid Howells struct vfsmount *mnt; 757ea5b778aSDavid Howells int err; 7589875cf80SDavid Howells 7599875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 7609875cf80SDavid Howells return -EREMOTE; 7619875cf80SDavid Howells 7620ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 7630ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 7640ec26fd0SMiklos Szeredi * the name. 7650ec26fd0SMiklos Szeredi * 7660ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 7675a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 7680ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 7690ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 7700ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 7710ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 7725a30d8a2SDavid Howells */ 7735a30d8a2SDavid Howells if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 774d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 7755a30d8a2SDavid Howells path->dentry->d_inode) 7769875cf80SDavid Howells return -EISDIR; 7770ec26fd0SMiklos Szeredi 7789875cf80SDavid Howells current->total_link_count++; 7799875cf80SDavid Howells if (current->total_link_count >= 40) 7809875cf80SDavid Howells return -ELOOP; 7819875cf80SDavid Howells 7829875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 7839875cf80SDavid Howells if (IS_ERR(mnt)) { 7849875cf80SDavid Howells /* 7859875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 7869875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 7879875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 7889875cf80SDavid Howells * 7899875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 7909875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 7919875cf80SDavid Howells * the path is inaccessible and we should say so. 7929875cf80SDavid Howells */ 79349084c3bSAl Viro if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) 7949875cf80SDavid Howells return -EREMOTE; 7959875cf80SDavid Howells return PTR_ERR(mnt); 79631e6b01fSNick Piggin } 797ea5b778aSDavid Howells 7989875cf80SDavid Howells if (!mnt) /* mount collision */ 7999875cf80SDavid Howells return 0; 8009875cf80SDavid Howells 8018aef1884SAl Viro if (!*need_mntput) { 8028aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 8038aef1884SAl Viro mntget(path->mnt); 8048aef1884SAl Viro *need_mntput = true; 8058aef1884SAl Viro } 80619a167afSAl Viro err = finish_automount(mnt, path); 807ea5b778aSDavid Howells 808ea5b778aSDavid Howells switch (err) { 809ea5b778aSDavid Howells case -EBUSY: 810ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 81119a167afSAl Viro return 0; 812ea5b778aSDavid Howells case 0: 8138aef1884SAl Viro path_put(path); 8149875cf80SDavid Howells path->mnt = mnt; 8159875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 8169875cf80SDavid Howells return 0; 81719a167afSAl Viro default: 81819a167afSAl Viro return err; 8199875cf80SDavid Howells } 82019a167afSAl Viro 821ea5b778aSDavid Howells } 8229875cf80SDavid Howells 8239875cf80SDavid Howells /* 8249875cf80SDavid Howells * Handle a dentry that is managed in some way. 825cc53ce53SDavid Howells * - Flagged for transit management (autofs) 8269875cf80SDavid Howells * - Flagged as mountpoint 8279875cf80SDavid Howells * - Flagged as automount point 8289875cf80SDavid Howells * 8299875cf80SDavid Howells * This may only be called in refwalk mode. 8309875cf80SDavid Howells * 8319875cf80SDavid Howells * Serialization is taken care of in namespace.c 8329875cf80SDavid Howells */ 8339875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 8349875cf80SDavid Howells { 8358aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 8369875cf80SDavid Howells unsigned managed; 8379875cf80SDavid Howells bool need_mntput = false; 8388aef1884SAl Viro int ret = 0; 8399875cf80SDavid Howells 8409875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 8419875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 8429875cf80SDavid Howells * the components of that value change under us */ 8439875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 8449875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 8459875cf80SDavid Howells unlikely(managed != 0)) { 846cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 847cc53ce53SDavid Howells * being held. */ 848cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 849cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 850cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 8511aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 852cc53ce53SDavid Howells if (ret < 0) 8538aef1884SAl Viro break; 854cc53ce53SDavid Howells } 855cc53ce53SDavid Howells 8569875cf80SDavid Howells /* Transit to a mounted filesystem. */ 8579875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 8589875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 8599875cf80SDavid Howells if (mounted) { 8609875cf80SDavid Howells dput(path->dentry); 8619875cf80SDavid Howells if (need_mntput) 862463ffb2eSAl Viro mntput(path->mnt); 863463ffb2eSAl Viro path->mnt = mounted; 864463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 8659875cf80SDavid Howells need_mntput = true; 8669875cf80SDavid Howells continue; 867463ffb2eSAl Viro } 868463ffb2eSAl Viro 8699875cf80SDavid Howells /* Something is mounted on this dentry in another 8709875cf80SDavid Howells * namespace and/or whatever was mounted there in this 8719875cf80SDavid Howells * namespace got unmounted before we managed to get the 8729875cf80SDavid Howells * vfsmount_lock */ 8731da177e4SLinus Torvalds } 8749875cf80SDavid Howells 8759875cf80SDavid Howells /* Handle an automount point */ 8769875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 8779875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 8789875cf80SDavid Howells if (ret < 0) 8798aef1884SAl Viro break; 8809875cf80SDavid Howells continue; 8819875cf80SDavid Howells } 8829875cf80SDavid Howells 8839875cf80SDavid Howells /* We didn't change the current path point */ 8849875cf80SDavid Howells break; 8859875cf80SDavid Howells } 8868aef1884SAl Viro 8878aef1884SAl Viro if (need_mntput && path->mnt == mnt) 8888aef1884SAl Viro mntput(path->mnt); 8898aef1884SAl Viro if (ret == -EISDIR) 8908aef1884SAl Viro ret = 0; 891a3fbbde7SAl Viro return ret < 0 ? ret : need_mntput; 8921da177e4SLinus Torvalds } 8931da177e4SLinus Torvalds 894cc53ce53SDavid Howells int follow_down_one(struct path *path) 8951da177e4SLinus Torvalds { 8961da177e4SLinus Torvalds struct vfsmount *mounted; 8971da177e4SLinus Torvalds 8981c755af4SAl Viro mounted = lookup_mnt(path); 8991da177e4SLinus Torvalds if (mounted) { 9009393bd07SAl Viro dput(path->dentry); 9019393bd07SAl Viro mntput(path->mnt); 9029393bd07SAl Viro path->mnt = mounted; 9039393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 9041da177e4SLinus Torvalds return 1; 9051da177e4SLinus Torvalds } 9061da177e4SLinus Torvalds return 0; 9071da177e4SLinus Torvalds } 9081da177e4SLinus Torvalds 90962a7375eSIan Kent static inline bool managed_dentry_might_block(struct dentry *dentry) 91062a7375eSIan Kent { 91162a7375eSIan Kent return (dentry->d_flags & DCACHE_MANAGE_TRANSIT && 91262a7375eSIan Kent dentry->d_op->d_manage(dentry, true) < 0); 91362a7375eSIan Kent } 91462a7375eSIan Kent 9159875cf80SDavid Howells /* 916287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 917287548e4SAl Viro * we meet a managed dentry that would need blocking. 9189875cf80SDavid Howells */ 9199875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 920287548e4SAl Viro struct inode **inode) 9219875cf80SDavid Howells { 92262a7375eSIan Kent for (;;) { 923c7105365SAl Viro struct mount *mounted; 92462a7375eSIan Kent /* 92562a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 92662a7375eSIan Kent * that wants to block transit. 92762a7375eSIan Kent */ 928287548e4SAl Viro if (unlikely(managed_dentry_might_block(path->dentry))) 929ab90911fSDavid Howells return false; 93062a7375eSIan Kent 93162a7375eSIan Kent if (!d_mountpoint(path->dentry)) 93262a7375eSIan Kent break; 93362a7375eSIan Kent 9349875cf80SDavid Howells mounted = __lookup_mnt(path->mnt, path->dentry, 1); 9359875cf80SDavid Howells if (!mounted) 9369875cf80SDavid Howells break; 937c7105365SAl Viro path->mnt = &mounted->mnt; 938c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 939a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 9409875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 94159430262SLinus Torvalds /* 94259430262SLinus Torvalds * Update the inode too. We don't need to re-check the 94359430262SLinus Torvalds * dentry sequence number here after this d_inode read, 94459430262SLinus Torvalds * because a mount-point is always pinned. 94559430262SLinus Torvalds */ 94659430262SLinus Torvalds *inode = path->dentry->d_inode; 9479875cf80SDavid Howells } 9489875cf80SDavid Howells return true; 9499875cf80SDavid Howells } 9509875cf80SDavid Howells 951dea39376SAl Viro static void follow_mount_rcu(struct nameidata *nd) 952287548e4SAl Viro { 953dea39376SAl Viro while (d_mountpoint(nd->path.dentry)) { 954c7105365SAl Viro struct mount *mounted; 955dea39376SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1); 956287548e4SAl Viro if (!mounted) 957287548e4SAl Viro break; 958c7105365SAl Viro nd->path.mnt = &mounted->mnt; 959c7105365SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 960dea39376SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 961287548e4SAl Viro } 962287548e4SAl Viro } 963287548e4SAl Viro 96431e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 96531e6b01fSNick Piggin { 96631e6b01fSNick Piggin set_root_rcu(nd); 96731e6b01fSNick Piggin 96831e6b01fSNick Piggin while (1) { 96931e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 97031e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 97131e6b01fSNick Piggin break; 97231e6b01fSNick Piggin } 97331e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 97431e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 97531e6b01fSNick Piggin struct dentry *parent = old->d_parent; 97631e6b01fSNick Piggin unsigned seq; 97731e6b01fSNick Piggin 97831e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 97931e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 980ef7562d5SAl Viro goto failed; 98131e6b01fSNick Piggin nd->path.dentry = parent; 98231e6b01fSNick Piggin nd->seq = seq; 98331e6b01fSNick Piggin break; 98431e6b01fSNick Piggin } 98531e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 98631e6b01fSNick Piggin break; 98731e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 98831e6b01fSNick Piggin } 989dea39376SAl Viro follow_mount_rcu(nd); 990dea39376SAl Viro nd->inode = nd->path.dentry->d_inode; 99131e6b01fSNick Piggin return 0; 992ef7562d5SAl Viro 993ef7562d5SAl Viro failed: 994ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 9955b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 996ef7562d5SAl Viro nd->root.mnt = NULL; 99732a7991bSAl Viro unlock_rcu_walk(); 998ef7562d5SAl Viro return -ECHILD; 99931e6b01fSNick Piggin } 100031e6b01fSNick Piggin 10019875cf80SDavid Howells /* 1002cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1003cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1004cc53ce53SDavid Howells * caller is permitted to proceed or not. 1005cc53ce53SDavid Howells */ 10067cc90cc3SAl Viro int follow_down(struct path *path) 1007cc53ce53SDavid Howells { 1008cc53ce53SDavid Howells unsigned managed; 1009cc53ce53SDavid Howells int ret; 1010cc53ce53SDavid Howells 1011cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1012cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1013cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1014cc53ce53SDavid Howells * being held. 1015cc53ce53SDavid Howells * 1016cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1017cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1018cc53ce53SDavid Howells * other than its daemon the right to mount on its 1019cc53ce53SDavid Howells * superstructure. 1020cc53ce53SDavid Howells * 1021cc53ce53SDavid Howells * The filesystem may sleep at this point. 1022cc53ce53SDavid Howells */ 1023cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1024cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1025cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1026ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 10271aed3e42SAl Viro path->dentry, false); 1028cc53ce53SDavid Howells if (ret < 0) 1029cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1030cc53ce53SDavid Howells } 1031cc53ce53SDavid Howells 1032cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1033cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1034cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1035cc53ce53SDavid Howells if (!mounted) 1036cc53ce53SDavid Howells break; 1037cc53ce53SDavid Howells dput(path->dentry); 1038cc53ce53SDavid Howells mntput(path->mnt); 1039cc53ce53SDavid Howells path->mnt = mounted; 1040cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1041cc53ce53SDavid Howells continue; 1042cc53ce53SDavid Howells } 1043cc53ce53SDavid Howells 1044cc53ce53SDavid Howells /* Don't handle automount points here */ 1045cc53ce53SDavid Howells break; 1046cc53ce53SDavid Howells } 1047cc53ce53SDavid Howells return 0; 1048cc53ce53SDavid Howells } 1049cc53ce53SDavid Howells 1050cc53ce53SDavid Howells /* 10519875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 10529875cf80SDavid Howells */ 10539875cf80SDavid Howells static void follow_mount(struct path *path) 10549875cf80SDavid Howells { 10559875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 10569875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10579875cf80SDavid Howells if (!mounted) 10589875cf80SDavid Howells break; 10599875cf80SDavid Howells dput(path->dentry); 10609875cf80SDavid Howells mntput(path->mnt); 10619875cf80SDavid Howells path->mnt = mounted; 10629875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 10639875cf80SDavid Howells } 10649875cf80SDavid Howells } 10659875cf80SDavid Howells 106631e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 10671da177e4SLinus Torvalds { 10682a737871SAl Viro set_root(nd); 1069e518ddb7SAndreas Mohr 10701da177e4SLinus Torvalds while(1) { 10714ac91378SJan Blunck struct dentry *old = nd->path.dentry; 10721da177e4SLinus Torvalds 10732a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 10742a737871SAl Viro nd->path.mnt == nd->root.mnt) { 10751da177e4SLinus Torvalds break; 10761da177e4SLinus Torvalds } 10774ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 10783088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 10793088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 10801da177e4SLinus Torvalds dput(old); 10811da177e4SLinus Torvalds break; 10821da177e4SLinus Torvalds } 10833088dd70SAl Viro if (!follow_up(&nd->path)) 10841da177e4SLinus Torvalds break; 10851da177e4SLinus Torvalds } 108679ed0226SAl Viro follow_mount(&nd->path); 108731e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 10881da177e4SLinus Torvalds } 10891da177e4SLinus Torvalds 10901da177e4SLinus Torvalds /* 1091bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1092bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1093bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1094bad61189SMiklos Szeredi * 1095bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1096baa03890SNick Piggin */ 1097bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1098201f956eSAl Viro unsigned int flags, bool *need_lookup) 1099baa03890SNick Piggin { 1100baa03890SNick Piggin struct dentry *dentry; 1101bad61189SMiklos Szeredi int error; 1102baa03890SNick Piggin 1103bad61189SMiklos Szeredi *need_lookup = false; 1104bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1105bad61189SMiklos Szeredi if (dentry) { 1106bad61189SMiklos Szeredi if (d_need_lookup(dentry)) { 1107bad61189SMiklos Szeredi *need_lookup = true; 1108bad61189SMiklos Szeredi } else if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1109201f956eSAl Viro error = d_revalidate(dentry, flags); 1110bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1111bad61189SMiklos Szeredi if (error < 0) { 1112bad61189SMiklos Szeredi dput(dentry); 1113bad61189SMiklos Szeredi return ERR_PTR(error); 1114bad61189SMiklos Szeredi } else if (!d_invalidate(dentry)) { 1115bad61189SMiklos Szeredi dput(dentry); 1116bad61189SMiklos Szeredi dentry = NULL; 1117bad61189SMiklos Szeredi } 1118bad61189SMiklos Szeredi } 1119bad61189SMiklos Szeredi } 1120bad61189SMiklos Szeredi } 1121baa03890SNick Piggin 1122bad61189SMiklos Szeredi if (!dentry) { 1123bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1124baa03890SNick Piggin if (unlikely(!dentry)) 1125baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1126baa03890SNick Piggin 1127bad61189SMiklos Szeredi *need_lookup = true; 1128baa03890SNick Piggin } 1129baa03890SNick Piggin return dentry; 1130baa03890SNick Piggin } 1131baa03890SNick Piggin 1132baa03890SNick Piggin /* 1133bad61189SMiklos Szeredi * Call i_op->lookup on the dentry. The dentry must be negative but may be 1134bad61189SMiklos Szeredi * hashed if it was pouplated with DCACHE_NEED_LOOKUP. 1135bad61189SMiklos Szeredi * 1136bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 113744396f4bSJosef Bacik */ 1138bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 113972bd866aSAl Viro unsigned int flags) 114044396f4bSJosef Bacik { 114144396f4bSJosef Bacik struct dentry *old; 114244396f4bSJosef Bacik 114344396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1144bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1145e188dc02SMiklos Szeredi dput(dentry); 114644396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1147e188dc02SMiklos Szeredi } 114844396f4bSJosef Bacik 114972bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 115044396f4bSJosef Bacik if (unlikely(old)) { 115144396f4bSJosef Bacik dput(dentry); 115244396f4bSJosef Bacik dentry = old; 115344396f4bSJosef Bacik } 115444396f4bSJosef Bacik return dentry; 115544396f4bSJosef Bacik } 115644396f4bSJosef Bacik 1157a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 115872bd866aSAl Viro struct dentry *base, unsigned int flags) 1159a3255546SAl Viro { 1160bad61189SMiklos Szeredi bool need_lookup; 1161a3255546SAl Viro struct dentry *dentry; 1162a3255546SAl Viro 116372bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1164bad61189SMiklos Szeredi if (!need_lookup) 1165a3255546SAl Viro return dentry; 1166bad61189SMiklos Szeredi 116772bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1168a3255546SAl Viro } 1169a3255546SAl Viro 117044396f4bSJosef Bacik /* 11711da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 11721da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 11731da177e4SLinus Torvalds * It _is_ time-critical. 11741da177e4SLinus Torvalds */ 1175697f514dSMiklos Szeredi static int lookup_fast(struct nameidata *nd, struct qstr *name, 117631e6b01fSNick Piggin struct path *path, struct inode **inode) 11771da177e4SLinus Torvalds { 11784ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 117931e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 11805a18fff2SAl Viro int need_reval = 1; 11815a18fff2SAl Viro int status = 1; 11829875cf80SDavid Howells int err; 11839875cf80SDavid Howells 11843cac260aSAl Viro /* 1185b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1186b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1187b04f784eSNick Piggin * do the non-racy lookup, below. 1188b04f784eSNick Piggin */ 118931e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 119031e6b01fSNick Piggin unsigned seq; 119112f8ad4bSLinus Torvalds dentry = __d_lookup_rcu(parent, name, &seq, nd->inode); 11925a18fff2SAl Viro if (!dentry) 11935a18fff2SAl Viro goto unlazy; 11945a18fff2SAl Viro 119512f8ad4bSLinus Torvalds /* 119612f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 119712f8ad4bSLinus Torvalds * the dentry name information from lookup. 119812f8ad4bSLinus Torvalds */ 119912f8ad4bSLinus Torvalds *inode = dentry->d_inode; 120012f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 120112f8ad4bSLinus Torvalds return -ECHILD; 120212f8ad4bSLinus Torvalds 120312f8ad4bSLinus Torvalds /* 120412f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 120512f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 120612f8ad4bSLinus Torvalds * 120712f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 120812f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 120912f8ad4bSLinus Torvalds */ 121031e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 121131e6b01fSNick Piggin return -ECHILD; 121231e6b01fSNick Piggin nd->seq = seq; 12135a18fff2SAl Viro 1214fa4ee159SMiklos Szeredi if (unlikely(d_need_lookup(dentry))) 1215fa4ee159SMiklos Szeredi goto unlazy; 121624643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 12174ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 12185a18fff2SAl Viro if (unlikely(status <= 0)) { 12195a18fff2SAl Viro if (status != -ECHILD) 12205a18fff2SAl Viro need_reval = 0; 12215a18fff2SAl Viro goto unlazy; 12225a18fff2SAl Viro } 122324643087SAl Viro } 122431e6b01fSNick Piggin path->mnt = mnt; 122531e6b01fSNick Piggin path->dentry = dentry; 1226d6e9bd25SAl Viro if (unlikely(!__follow_mount_rcu(nd, path, inode))) 1227d6e9bd25SAl Viro goto unlazy; 1228d6e9bd25SAl Viro if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) 1229d6e9bd25SAl Viro goto unlazy; 12309875cf80SDavid Howells return 0; 12315a18fff2SAl Viro unlazy: 123219660af7SAl Viro if (unlazy_walk(nd, dentry)) 12335a18fff2SAl Viro return -ECHILD; 12345a18fff2SAl Viro } else { 123531e6b01fSNick Piggin dentry = __d_lookup(parent, name); 123624643087SAl Viro } 12375a18fff2SAl Viro 123881e6f520SAl Viro if (unlikely(!dentry)) 123981e6f520SAl Viro goto need_lookup; 12405a18fff2SAl Viro 124181e6f520SAl Viro if (unlikely(d_need_lookup(dentry))) { 124281e6f520SAl Viro dput(dentry); 124381e6f520SAl Viro goto need_lookup; 12445a18fff2SAl Viro } 124581e6f520SAl Viro 12465a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 12474ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 12485a18fff2SAl Viro if (unlikely(status <= 0)) { 12495a18fff2SAl Viro if (status < 0) { 12505a18fff2SAl Viro dput(dentry); 12515a18fff2SAl Viro return status; 12525a18fff2SAl Viro } 12535a18fff2SAl Viro if (!d_invalidate(dentry)) { 12545a18fff2SAl Viro dput(dentry); 125581e6f520SAl Viro goto need_lookup; 12565a18fff2SAl Viro } 12575a18fff2SAl Viro } 1258697f514dSMiklos Szeredi 12591da177e4SLinus Torvalds path->mnt = mnt; 12601da177e4SLinus Torvalds path->dentry = dentry; 12619875cf80SDavid Howells err = follow_managed(path, nd->flags); 126289312214SIan Kent if (unlikely(err < 0)) { 126389312214SIan Kent path_put_conditional(path, nd); 12649875cf80SDavid Howells return err; 126589312214SIan Kent } 1266a3fbbde7SAl Viro if (err) 1267a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 126831e6b01fSNick Piggin *inode = path->dentry->d_inode; 12691da177e4SLinus Torvalds return 0; 127081e6f520SAl Viro 127181e6f520SAl Viro need_lookup: 1272697f514dSMiklos Szeredi return 1; 1273697f514dSMiklos Szeredi } 1274697f514dSMiklos Szeredi 1275697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1276697f514dSMiklos Szeredi static int lookup_slow(struct nameidata *nd, struct qstr *name, 1277697f514dSMiklos Szeredi struct path *path) 1278697f514dSMiklos Szeredi { 1279697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1280697f514dSMiklos Szeredi int err; 1281697f514dSMiklos Szeredi 1282697f514dSMiklos Szeredi parent = nd->path.dentry; 128381e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 128481e6f520SAl Viro 128581e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 128672bd866aSAl Viro dentry = __lookup_hash(name, parent, nd->flags); 128781e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 128881e6f520SAl Viro if (IS_ERR(dentry)) 128981e6f520SAl Viro return PTR_ERR(dentry); 1290697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1291697f514dSMiklos Szeredi path->dentry = dentry; 1292697f514dSMiklos Szeredi err = follow_managed(path, nd->flags); 1293697f514dSMiklos Szeredi if (unlikely(err < 0)) { 1294697f514dSMiklos Szeredi path_put_conditional(path, nd); 1295697f514dSMiklos Szeredi return err; 1296697f514dSMiklos Szeredi } 1297697f514dSMiklos Szeredi if (err) 1298697f514dSMiklos Szeredi nd->flags |= LOOKUP_JUMPED; 1299697f514dSMiklos Szeredi return 0; 13001da177e4SLinus Torvalds } 13011da177e4SLinus Torvalds 130252094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 130352094c8aSAl Viro { 130452094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 13054ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 130652094c8aSAl Viro if (err != -ECHILD) 130752094c8aSAl Viro return err; 130819660af7SAl Viro if (unlazy_walk(nd, NULL)) 130952094c8aSAl Viro return -ECHILD; 131052094c8aSAl Viro } 13114ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 131252094c8aSAl Viro } 131352094c8aSAl Viro 13149856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 13159856fa1bSAl Viro { 13169856fa1bSAl Viro if (type == LAST_DOTDOT) { 13179856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 13189856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 13199856fa1bSAl Viro return -ECHILD; 13209856fa1bSAl Viro } else 13219856fa1bSAl Viro follow_dotdot(nd); 13229856fa1bSAl Viro } 13239856fa1bSAl Viro return 0; 13249856fa1bSAl Viro } 13259856fa1bSAl Viro 1326951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1327951361f9SAl Viro { 1328951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1329951361f9SAl Viro path_put(&nd->path); 1330951361f9SAl Viro } else { 1331951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 13325b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1333951361f9SAl Viro nd->root.mnt = NULL; 133432a7991bSAl Viro unlock_rcu_walk(); 1335951361f9SAl Viro } 1336951361f9SAl Viro } 1337951361f9SAl Viro 13383ddcd056SLinus Torvalds /* 13393ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 13403ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 13413ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 13423ddcd056SLinus Torvalds * for the common case. 13433ddcd056SLinus Torvalds */ 13447813b94aSLinus Torvalds static inline int should_follow_link(struct inode *inode, int follow) 13453ddcd056SLinus Torvalds { 13463ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) { 13473ddcd056SLinus Torvalds if (likely(inode->i_op->follow_link)) 13483ddcd056SLinus Torvalds return follow; 13493ddcd056SLinus Torvalds 13503ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 13513ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 13523ddcd056SLinus Torvalds inode->i_opflags |= IOP_NOFOLLOW; 13533ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 13543ddcd056SLinus Torvalds } 13553ddcd056SLinus Torvalds return 0; 13563ddcd056SLinus Torvalds } 13573ddcd056SLinus Torvalds 1358ce57dfc1SAl Viro static inline int walk_component(struct nameidata *nd, struct path *path, 1359ce57dfc1SAl Viro struct qstr *name, int type, int follow) 1360ce57dfc1SAl Viro { 1361ce57dfc1SAl Viro struct inode *inode; 1362ce57dfc1SAl Viro int err; 1363ce57dfc1SAl Viro /* 1364ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1365ce57dfc1SAl Viro * to be able to know about the current root directory and 1366ce57dfc1SAl Viro * parent relationships. 1367ce57dfc1SAl Viro */ 1368ce57dfc1SAl Viro if (unlikely(type != LAST_NORM)) 1369ce57dfc1SAl Viro return handle_dots(nd, type); 1370697f514dSMiklos Szeredi err = lookup_fast(nd, name, path, &inode); 1371ce57dfc1SAl Viro if (unlikely(err)) { 1372697f514dSMiklos Szeredi if (err < 0) 1373697f514dSMiklos Szeredi goto out_err; 1374697f514dSMiklos Szeredi 1375697f514dSMiklos Szeredi err = lookup_slow(nd, name, path); 1376697f514dSMiklos Szeredi if (err < 0) 1377697f514dSMiklos Szeredi goto out_err; 1378697f514dSMiklos Szeredi 1379697f514dSMiklos Szeredi inode = path->dentry->d_inode; 1380ce57dfc1SAl Viro } 1381697f514dSMiklos Szeredi err = -ENOENT; 1382697f514dSMiklos Szeredi if (!inode) 1383697f514dSMiklos Szeredi goto out_path_put; 1384697f514dSMiklos Szeredi 13857813b94aSLinus Torvalds if (should_follow_link(inode, follow)) { 138619660af7SAl Viro if (nd->flags & LOOKUP_RCU) { 138719660af7SAl Viro if (unlikely(unlazy_walk(nd, path->dentry))) { 1388697f514dSMiklos Szeredi err = -ECHILD; 1389697f514dSMiklos Szeredi goto out_err; 139019660af7SAl Viro } 139119660af7SAl Viro } 1392ce57dfc1SAl Viro BUG_ON(inode != path->dentry->d_inode); 1393ce57dfc1SAl Viro return 1; 1394ce57dfc1SAl Viro } 1395ce57dfc1SAl Viro path_to_nameidata(path, nd); 1396ce57dfc1SAl Viro nd->inode = inode; 1397ce57dfc1SAl Viro return 0; 1398697f514dSMiklos Szeredi 1399697f514dSMiklos Szeredi out_path_put: 1400697f514dSMiklos Szeredi path_to_nameidata(path, nd); 1401697f514dSMiklos Szeredi out_err: 1402697f514dSMiklos Szeredi terminate_walk(nd); 1403697f514dSMiklos Szeredi return err; 1404ce57dfc1SAl Viro } 1405ce57dfc1SAl Viro 14061da177e4SLinus Torvalds /* 1407b356379aSAl Viro * This limits recursive symlink follows to 8, while 1408b356379aSAl Viro * limiting consecutive symlinks to 40. 1409b356379aSAl Viro * 1410b356379aSAl Viro * Without that kind of total limit, nasty chains of consecutive 1411b356379aSAl Viro * symlinks can cause almost arbitrarily long lookups. 1412b356379aSAl Viro */ 1413b356379aSAl Viro static inline int nested_symlink(struct path *path, struct nameidata *nd) 1414b356379aSAl Viro { 1415b356379aSAl Viro int res; 1416b356379aSAl Viro 1417b356379aSAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 1418b356379aSAl Viro path_put_conditional(path, nd); 1419b356379aSAl Viro path_put(&nd->path); 1420b356379aSAl Viro return -ELOOP; 1421b356379aSAl Viro } 14221a4022f8SErez Zadok BUG_ON(nd->depth >= MAX_NESTED_LINKS); 1423b356379aSAl Viro 1424b356379aSAl Viro nd->depth++; 1425b356379aSAl Viro current->link_count++; 1426b356379aSAl Viro 1427b356379aSAl Viro do { 1428b356379aSAl Viro struct path link = *path; 1429b356379aSAl Viro void *cookie; 1430574197e0SAl Viro 1431574197e0SAl Viro res = follow_link(&link, nd, &cookie); 14326d7b5aaeSAl Viro if (res) 14336d7b5aaeSAl Viro break; 1434b356379aSAl Viro res = walk_component(nd, path, &nd->last, 1435b356379aSAl Viro nd->last_type, LOOKUP_FOLLOW); 1436574197e0SAl Viro put_link(nd, &link, cookie); 1437b356379aSAl Viro } while (res > 0); 1438b356379aSAl Viro 1439b356379aSAl Viro current->link_count--; 1440b356379aSAl Viro nd->depth--; 1441b356379aSAl Viro return res; 1442b356379aSAl Viro } 1443b356379aSAl Viro 1444b356379aSAl Viro /* 14453ddcd056SLinus Torvalds * We really don't want to look at inode->i_op->lookup 14463ddcd056SLinus Torvalds * when we don't have to. So we keep a cache bit in 14473ddcd056SLinus Torvalds * the inode ->i_opflags field that says "yes, we can 14483ddcd056SLinus Torvalds * do lookup on this inode". 14493ddcd056SLinus Torvalds */ 14503ddcd056SLinus Torvalds static inline int can_lookup(struct inode *inode) 14513ddcd056SLinus Torvalds { 14523ddcd056SLinus Torvalds if (likely(inode->i_opflags & IOP_LOOKUP)) 14533ddcd056SLinus Torvalds return 1; 14543ddcd056SLinus Torvalds if (likely(!inode->i_op->lookup)) 14553ddcd056SLinus Torvalds return 0; 14563ddcd056SLinus Torvalds 14573ddcd056SLinus Torvalds /* We do this once for the lifetime of the inode */ 14583ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 14593ddcd056SLinus Torvalds inode->i_opflags |= IOP_LOOKUP; 14603ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 14613ddcd056SLinus Torvalds return 1; 14623ddcd056SLinus Torvalds } 14633ddcd056SLinus Torvalds 1464bfcfaa77SLinus Torvalds /* 1465bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1466bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1467bfcfaa77SLinus Torvalds * 1468bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1469bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1470bfcfaa77SLinus Torvalds * fast. 1471bfcfaa77SLinus Torvalds * 1472bfcfaa77SLinus Torvalds * - Little-endian machines (so that we can generate the mask 1473bfcfaa77SLinus Torvalds * of low bytes efficiently). Again, we *could* do a byte 1474bfcfaa77SLinus Torvalds * swapping load on big-endian architectures if that is not 1475bfcfaa77SLinus Torvalds * expensive enough to make the optimization worthless. 1476bfcfaa77SLinus Torvalds * 1477bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1478bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1479bfcfaa77SLinus Torvalds * crossing operation. 1480bfcfaa77SLinus Torvalds * 1481bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1482bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1483bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1484bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1485bfcfaa77SLinus Torvalds */ 1486bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1487bfcfaa77SLinus Torvalds 1488f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1489bfcfaa77SLinus Torvalds 1490f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1491bfcfaa77SLinus Torvalds 1492bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1493bfcfaa77SLinus Torvalds { 1494bfcfaa77SLinus Torvalds hash += hash >> (8*sizeof(int)); 1495bfcfaa77SLinus Torvalds return hash; 1496bfcfaa77SLinus Torvalds } 1497bfcfaa77SLinus Torvalds 1498bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1499bfcfaa77SLinus Torvalds 1500bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1501bfcfaa77SLinus Torvalds 1502bfcfaa77SLinus Torvalds #endif 1503bfcfaa77SLinus Torvalds 1504bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1505bfcfaa77SLinus Torvalds { 1506bfcfaa77SLinus Torvalds unsigned long a, mask; 1507bfcfaa77SLinus Torvalds unsigned long hash = 0; 1508bfcfaa77SLinus Torvalds 1509bfcfaa77SLinus Torvalds for (;;) { 1510e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1511bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1512bfcfaa77SLinus Torvalds break; 1513bfcfaa77SLinus Torvalds hash += a; 1514f132c5beSAl Viro hash *= 9; 1515bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1516bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1517bfcfaa77SLinus Torvalds if (!len) 1518bfcfaa77SLinus Torvalds goto done; 1519bfcfaa77SLinus Torvalds } 1520bfcfaa77SLinus Torvalds mask = ~(~0ul << len*8); 1521bfcfaa77SLinus Torvalds hash += mask & a; 1522bfcfaa77SLinus Torvalds done: 1523bfcfaa77SLinus Torvalds return fold_hash(hash); 1524bfcfaa77SLinus Torvalds } 1525bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1526bfcfaa77SLinus Torvalds 1527bfcfaa77SLinus Torvalds /* 1528bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1529bfcfaa77SLinus Torvalds * return the length of the component; 1530bfcfaa77SLinus Torvalds */ 1531bfcfaa77SLinus Torvalds static inline unsigned long hash_name(const char *name, unsigned int *hashp) 1532bfcfaa77SLinus Torvalds { 153336126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 153436126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1535bfcfaa77SLinus Torvalds 1536bfcfaa77SLinus Torvalds hash = a = 0; 1537bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1538bfcfaa77SLinus Torvalds do { 1539bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1540bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1541e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 154236126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 154336126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1544bfcfaa77SLinus Torvalds 154536126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 154636126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 154736126f8fSLinus Torvalds 154836126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 154936126f8fSLinus Torvalds 155036126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 1551bfcfaa77SLinus Torvalds *hashp = fold_hash(hash); 1552bfcfaa77SLinus Torvalds 155336126f8fSLinus Torvalds return len + find_zero(mask); 1554bfcfaa77SLinus Torvalds } 1555bfcfaa77SLinus Torvalds 1556bfcfaa77SLinus Torvalds #else 1557bfcfaa77SLinus Torvalds 15580145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 15590145acc2SLinus Torvalds { 15600145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 15610145acc2SLinus Torvalds while (len--) 15620145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 15630145acc2SLinus Torvalds return end_name_hash(hash); 15640145acc2SLinus Torvalds } 1565ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 15660145acc2SLinus Torvalds 15673ddcd056SLinus Torvalds /* 1568200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1569200e9ef7SLinus Torvalds * one character. 1570200e9ef7SLinus Torvalds */ 1571200e9ef7SLinus Torvalds static inline unsigned long hash_name(const char *name, unsigned int *hashp) 1572200e9ef7SLinus Torvalds { 1573200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1574200e9ef7SLinus Torvalds unsigned long len = 0, c; 1575200e9ef7SLinus Torvalds 1576200e9ef7SLinus Torvalds c = (unsigned char)*name; 1577200e9ef7SLinus Torvalds do { 1578200e9ef7SLinus Torvalds len++; 1579200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1580200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1581200e9ef7SLinus Torvalds } while (c && c != '/'); 1582200e9ef7SLinus Torvalds *hashp = end_name_hash(hash); 1583200e9ef7SLinus Torvalds return len; 1584200e9ef7SLinus Torvalds } 1585200e9ef7SLinus Torvalds 1586bfcfaa77SLinus Torvalds #endif 1587bfcfaa77SLinus Torvalds 1588200e9ef7SLinus Torvalds /* 15891da177e4SLinus Torvalds * Name resolution. 1590ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1591ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 15921da177e4SLinus Torvalds * 1593ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1594ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 15951da177e4SLinus Torvalds */ 15966de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 15971da177e4SLinus Torvalds { 15981da177e4SLinus Torvalds struct path next; 15991da177e4SLinus Torvalds int err; 16001da177e4SLinus Torvalds 16011da177e4SLinus Torvalds while (*name=='/') 16021da177e4SLinus Torvalds name++; 16031da177e4SLinus Torvalds if (!*name) 1604086e183aSAl Viro return 0; 16051da177e4SLinus Torvalds 16061da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 16071da177e4SLinus Torvalds for(;;) { 16081da177e4SLinus Torvalds struct qstr this; 1609200e9ef7SLinus Torvalds long len; 1610fe479a58SAl Viro int type; 16111da177e4SLinus Torvalds 161252094c8aSAl Viro err = may_lookup(nd); 16131da177e4SLinus Torvalds if (err) 16141da177e4SLinus Torvalds break; 16151da177e4SLinus Torvalds 1616200e9ef7SLinus Torvalds len = hash_name(name, &this.hash); 16171da177e4SLinus Torvalds this.name = name; 1618200e9ef7SLinus Torvalds this.len = len; 16191da177e4SLinus Torvalds 1620fe479a58SAl Viro type = LAST_NORM; 1621200e9ef7SLinus Torvalds if (name[0] == '.') switch (len) { 1622fe479a58SAl Viro case 2: 1623200e9ef7SLinus Torvalds if (name[1] == '.') { 1624fe479a58SAl Viro type = LAST_DOTDOT; 162516c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 162616c2cd71SAl Viro } 1627fe479a58SAl Viro break; 1628fe479a58SAl Viro case 1: 1629fe479a58SAl Viro type = LAST_DOT; 1630fe479a58SAl Viro } 16315a202bcdSAl Viro if (likely(type == LAST_NORM)) { 16325a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 163316c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 16345a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 16355a202bcdSAl Viro err = parent->d_op->d_hash(parent, nd->inode, 16365a202bcdSAl Viro &this); 16375a202bcdSAl Viro if (err < 0) 16385a202bcdSAl Viro break; 16395a202bcdSAl Viro } 16405a202bcdSAl Viro } 1641fe479a58SAl Viro 1642200e9ef7SLinus Torvalds if (!name[len]) 16431da177e4SLinus Torvalds goto last_component; 1644200e9ef7SLinus Torvalds /* 1645200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1646200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1647200e9ef7SLinus Torvalds */ 1648200e9ef7SLinus Torvalds do { 1649200e9ef7SLinus Torvalds len++; 1650200e9ef7SLinus Torvalds } while (unlikely(name[len] == '/')); 1651200e9ef7SLinus Torvalds if (!name[len]) 1652b356379aSAl Viro goto last_component; 1653200e9ef7SLinus Torvalds name += len; 16541da177e4SLinus Torvalds 1655ce57dfc1SAl Viro err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW); 1656ce57dfc1SAl Viro if (err < 0) 1657ce57dfc1SAl Viro return err; 1658fe479a58SAl Viro 1659ce57dfc1SAl Viro if (err) { 1660b356379aSAl Viro err = nested_symlink(&next, nd); 16611da177e4SLinus Torvalds if (err) 1662a7472babSAl Viro return err; 166331e6b01fSNick Piggin } 16643ddcd056SLinus Torvalds if (can_lookup(nd->inode)) 16651da177e4SLinus Torvalds continue; 16663ddcd056SLinus Torvalds err = -ENOTDIR; 16673ddcd056SLinus Torvalds break; 16681da177e4SLinus Torvalds /* here ends the main loop */ 16691da177e4SLinus Torvalds 16701da177e4SLinus Torvalds last_component: 1671ce57dfc1SAl Viro nd->last = this; 1672ce57dfc1SAl Viro nd->last_type = type; 1673ce57dfc1SAl Viro return 0; 1674ce57dfc1SAl Viro } 1675951361f9SAl Viro terminate_walk(nd); 16761da177e4SLinus Torvalds return err; 16771da177e4SLinus Torvalds } 16781da177e4SLinus Torvalds 167970e9b357SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, 168070e9b357SAl Viro struct nameidata *nd, struct file **fp) 168131e6b01fSNick Piggin { 168231e6b01fSNick Piggin int retval = 0; 168331e6b01fSNick Piggin int fput_needed; 168431e6b01fSNick Piggin struct file *file; 168531e6b01fSNick Piggin 168631e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 168716c2cd71SAl Viro nd->flags = flags | LOOKUP_JUMPED; 168831e6b01fSNick Piggin nd->depth = 0; 16895b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 16905b6ca027SAl Viro struct inode *inode = nd->root.dentry->d_inode; 169173d049a4SAl Viro if (*name) { 16925b6ca027SAl Viro if (!inode->i_op->lookup) 16935b6ca027SAl Viro return -ENOTDIR; 16945b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 16955b6ca027SAl Viro if (retval) 16965b6ca027SAl Viro return retval; 169773d049a4SAl Viro } 16985b6ca027SAl Viro nd->path = nd->root; 16995b6ca027SAl Viro nd->inode = inode; 17005b6ca027SAl Viro if (flags & LOOKUP_RCU) { 170132a7991bSAl Viro lock_rcu_walk(); 17025b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 17035b6ca027SAl Viro } else { 17045b6ca027SAl Viro path_get(&nd->path); 17055b6ca027SAl Viro } 17065b6ca027SAl Viro return 0; 17075b6ca027SAl Viro } 17085b6ca027SAl Viro 170931e6b01fSNick Piggin nd->root.mnt = NULL; 171031e6b01fSNick Piggin 171131e6b01fSNick Piggin if (*name=='/') { 1712e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 171332a7991bSAl Viro lock_rcu_walk(); 1714e41f7d4eSAl Viro set_root_rcu(nd); 1715e41f7d4eSAl Viro } else { 1716e41f7d4eSAl Viro set_root(nd); 1717e41f7d4eSAl Viro path_get(&nd->root); 1718e41f7d4eSAl Viro } 171931e6b01fSNick Piggin nd->path = nd->root; 172031e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1721e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 172231e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1723c28cc364SNick Piggin unsigned seq; 172431e6b01fSNick Piggin 172532a7991bSAl Viro lock_rcu_walk(); 172631e6b01fSNick Piggin 1727c28cc364SNick Piggin do { 1728c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 172931e6b01fSNick Piggin nd->path = fs->pwd; 1730c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1731c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1732e41f7d4eSAl Viro } else { 1733e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1734e41f7d4eSAl Viro } 173531e6b01fSNick Piggin } else { 173631e6b01fSNick Piggin struct dentry *dentry; 173731e6b01fSNick Piggin 17381abf0c71SAl Viro file = fget_raw_light(dfd, &fput_needed); 173931e6b01fSNick Piggin retval = -EBADF; 174031e6b01fSNick Piggin if (!file) 174131e6b01fSNick Piggin goto out_fail; 174231e6b01fSNick Piggin 174331e6b01fSNick Piggin dentry = file->f_path.dentry; 174431e6b01fSNick Piggin 1745f52e0c11SAl Viro if (*name) { 174631e6b01fSNick Piggin retval = -ENOTDIR; 174731e6b01fSNick Piggin if (!S_ISDIR(dentry->d_inode->i_mode)) 174831e6b01fSNick Piggin goto fput_fail; 174931e6b01fSNick Piggin 17504ad5abb3SAl Viro retval = inode_permission(dentry->d_inode, MAY_EXEC); 175131e6b01fSNick Piggin if (retval) 175231e6b01fSNick Piggin goto fput_fail; 1753f52e0c11SAl Viro } 175431e6b01fSNick Piggin 175531e6b01fSNick Piggin nd->path = file->f_path; 1756e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 175731e6b01fSNick Piggin if (fput_needed) 175870e9b357SAl Viro *fp = file; 1759c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 176032a7991bSAl Viro lock_rcu_walk(); 17615590ff0dSUlrich Drepper } else { 17625dd784d0SJan Blunck path_get(&file->f_path); 17635590ff0dSUlrich Drepper fput_light(file, fput_needed); 17641da177e4SLinus Torvalds } 1765e41f7d4eSAl Viro } 1766e41f7d4eSAl Viro 176731e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 17689b4a9b14SAl Viro return 0; 17692dfdd266SJosef 'Jeff' Sipek 17709b4a9b14SAl Viro fput_fail: 17719b4a9b14SAl Viro fput_light(file, fput_needed); 17729b4a9b14SAl Viro out_fail: 17739b4a9b14SAl Viro return retval; 17749b4a9b14SAl Viro } 17759b4a9b14SAl Viro 1776bd92d7feSAl Viro static inline int lookup_last(struct nameidata *nd, struct path *path) 1777bd92d7feSAl Viro { 1778bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1779bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1780bd92d7feSAl Viro 1781bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 1782bd92d7feSAl Viro return walk_component(nd, path, &nd->last, nd->last_type, 1783bd92d7feSAl Viro nd->flags & LOOKUP_FOLLOW); 1784bd92d7feSAl Viro } 1785bd92d7feSAl Viro 17869b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1787ee0827cdSAl Viro static int path_lookupat(int dfd, const char *name, 17889b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 17899b4a9b14SAl Viro { 179070e9b357SAl Viro struct file *base = NULL; 1791bd92d7feSAl Viro struct path path; 1792bd92d7feSAl Viro int err; 179331e6b01fSNick Piggin 179431e6b01fSNick Piggin /* 179531e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 179631e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 179731e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 179831e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 179931e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 180031e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 180131e6b01fSNick Piggin * analogue, foo_rcu(). 180231e6b01fSNick Piggin * 180331e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 180431e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 180531e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 180631e6b01fSNick Piggin * be able to complete). 180731e6b01fSNick Piggin */ 1808bd92d7feSAl Viro err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); 1809ee0827cdSAl Viro 1810bd92d7feSAl Viro if (unlikely(err)) 1811bd92d7feSAl Viro return err; 1812ee0827cdSAl Viro 1813ee0827cdSAl Viro current->total_link_count = 0; 1814bd92d7feSAl Viro err = link_path_walk(name, nd); 1815bd92d7feSAl Viro 1816bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 1817bd92d7feSAl Viro err = lookup_last(nd, &path); 1818bd92d7feSAl Viro while (err > 0) { 1819bd92d7feSAl Viro void *cookie; 1820bd92d7feSAl Viro struct path link = path; 1821bd92d7feSAl Viro nd->flags |= LOOKUP_PARENT; 1822574197e0SAl Viro err = follow_link(&link, nd, &cookie); 18236d7b5aaeSAl Viro if (err) 18246d7b5aaeSAl Viro break; 1825bd92d7feSAl Viro err = lookup_last(nd, &path); 1826574197e0SAl Viro put_link(nd, &link, cookie); 1827bd92d7feSAl Viro } 1828bd92d7feSAl Viro } 1829ee0827cdSAl Viro 18309f1fafeeSAl Viro if (!err) 18319f1fafeeSAl Viro err = complete_walk(nd); 1832bd92d7feSAl Viro 1833bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 1834bd92d7feSAl Viro if (!nd->inode->i_op->lookup) { 1835bd92d7feSAl Viro path_put(&nd->path); 1836bd23a539SAl Viro err = -ENOTDIR; 1837bd92d7feSAl Viro } 1838bd92d7feSAl Viro } 183916c2cd71SAl Viro 184070e9b357SAl Viro if (base) 184170e9b357SAl Viro fput(base); 1842ee0827cdSAl Viro 18435b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 184431e6b01fSNick Piggin path_put(&nd->root); 184531e6b01fSNick Piggin nd->root.mnt = NULL; 184631e6b01fSNick Piggin } 1847bd92d7feSAl Viro return err; 184831e6b01fSNick Piggin } 184931e6b01fSNick Piggin 1850ee0827cdSAl Viro static int do_path_lookup(int dfd, const char *name, 1851ee0827cdSAl Viro unsigned int flags, struct nameidata *nd) 1852ee0827cdSAl Viro { 1853ee0827cdSAl Viro int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 1854ee0827cdSAl Viro if (unlikely(retval == -ECHILD)) 1855ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags, nd); 1856ee0827cdSAl Viro if (unlikely(retval == -ESTALE)) 1857ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 1858ee0827cdSAl Viro 185931e6b01fSNick Piggin if (likely(!retval)) { 186031e6b01fSNick Piggin if (unlikely(!audit_dummy_context())) { 186131e6b01fSNick Piggin if (nd->path.dentry && nd->inode) 186231e6b01fSNick Piggin audit_inode(name, nd->path.dentry); 186331e6b01fSNick Piggin } 186431e6b01fSNick Piggin } 1865170aa3d0SUlrich Drepper return retval; 18661da177e4SLinus Torvalds } 18671da177e4SLinus Torvalds 186879714f72SAl Viro /* does lookup, returns the object with parent locked */ 186979714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 18705590ff0dSUlrich Drepper { 187179714f72SAl Viro struct nameidata nd; 187279714f72SAl Viro struct dentry *d; 187379714f72SAl Viro int err = do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, &nd); 187479714f72SAl Viro if (err) 187579714f72SAl Viro return ERR_PTR(err); 187679714f72SAl Viro if (nd.last_type != LAST_NORM) { 187779714f72SAl Viro path_put(&nd.path); 187879714f72SAl Viro return ERR_PTR(-EINVAL); 187979714f72SAl Viro } 188079714f72SAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 18811e0ea001SAl Viro d = __lookup_hash(&nd.last, nd.path.dentry, 0); 188279714f72SAl Viro if (IS_ERR(d)) { 188379714f72SAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 188479714f72SAl Viro path_put(&nd.path); 188579714f72SAl Viro return d; 188679714f72SAl Viro } 188779714f72SAl Viro *path = nd.path; 188879714f72SAl Viro return d; 18895590ff0dSUlrich Drepper } 18905590ff0dSUlrich Drepper 1891d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 1892d1811465SAl Viro { 1893d1811465SAl Viro struct nameidata nd; 1894d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 1895d1811465SAl Viro if (!res) 1896d1811465SAl Viro *path = nd.path; 1897d1811465SAl Viro return res; 1898d1811465SAl Viro } 1899d1811465SAl Viro 190016f18200SJosef 'Jeff' Sipek /** 190116f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 190216f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 190316f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 190416f18200SJosef 'Jeff' Sipek * @name: pointer to file name 190516f18200SJosef 'Jeff' Sipek * @flags: lookup flags 1906e0a01249SAl Viro * @path: pointer to struct path to fill 190716f18200SJosef 'Jeff' Sipek */ 190816f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 190916f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 1910e0a01249SAl Viro struct path *path) 191116f18200SJosef 'Jeff' Sipek { 1912e0a01249SAl Viro struct nameidata nd; 1913e0a01249SAl Viro int err; 1914e0a01249SAl Viro nd.root.dentry = dentry; 1915e0a01249SAl Viro nd.root.mnt = mnt; 1916e0a01249SAl Viro BUG_ON(flags & LOOKUP_PARENT); 19175b6ca027SAl Viro /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ 1918e0a01249SAl Viro err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd); 1919e0a01249SAl Viro if (!err) 1920e0a01249SAl Viro *path = nd.path; 1921e0a01249SAl Viro return err; 192216f18200SJosef 'Jeff' Sipek } 192316f18200SJosef 'Jeff' Sipek 1924057f6c01SJames Morris /* 1925057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1926057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1927057f6c01SJames Morris * SMP-safe. 1928057f6c01SJames Morris */ 1929a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 19301da177e4SLinus Torvalds { 193172bd866aSAl Viro return __lookup_hash(&nd->last, nd->path.dentry, nd->flags); 19321da177e4SLinus Torvalds } 19331da177e4SLinus Torvalds 1934eead1911SChristoph Hellwig /** 1935a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1936eead1911SChristoph Hellwig * @name: pathname component to lookup 1937eead1911SChristoph Hellwig * @base: base directory to lookup from 1938eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1939eead1911SChristoph Hellwig * 1940a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1941a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1942eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1943eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1944eead1911SChristoph Hellwig */ 1945057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1946057f6c01SJames Morris { 1947057f6c01SJames Morris struct qstr this; 19486a96ba54SAl Viro unsigned int c; 1949cda309deSMiklos Szeredi int err; 1950057f6c01SJames Morris 19512f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 19522f9092e1SDavid Woodhouse 19536a96ba54SAl Viro this.name = name; 19546a96ba54SAl Viro this.len = len; 19550145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 19566a96ba54SAl Viro if (!len) 19576a96ba54SAl Viro return ERR_PTR(-EACCES); 19586a96ba54SAl Viro 19596a96ba54SAl Viro while (len--) { 19606a96ba54SAl Viro c = *(const unsigned char *)name++; 19616a96ba54SAl Viro if (c == '/' || c == '\0') 19626a96ba54SAl Viro return ERR_PTR(-EACCES); 19636a96ba54SAl Viro } 19645a202bcdSAl Viro /* 19655a202bcdSAl Viro * See if the low-level filesystem might want 19665a202bcdSAl Viro * to use its own hash.. 19675a202bcdSAl Viro */ 19685a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 19695a202bcdSAl Viro int err = base->d_op->d_hash(base, base->d_inode, &this); 19705a202bcdSAl Viro if (err < 0) 19715a202bcdSAl Viro return ERR_PTR(err); 19725a202bcdSAl Viro } 1973eead1911SChristoph Hellwig 1974cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 1975cda309deSMiklos Szeredi if (err) 1976cda309deSMiklos Szeredi return ERR_PTR(err); 1977cda309deSMiklos Szeredi 197872bd866aSAl Viro return __lookup_hash(&this, base, 0); 1979057f6c01SJames Morris } 1980057f6c01SJames Morris 19811fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 19821fa1e7f6SAndy Whitcroft struct path *path, int *empty) 19831da177e4SLinus Torvalds { 19842d8f3038SAl Viro struct nameidata nd; 19851fa1e7f6SAndy Whitcroft char *tmp = getname_flags(name, flags, empty); 19861da177e4SLinus Torvalds int err = PTR_ERR(tmp); 19871da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 19882d8f3038SAl Viro 19892d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 19902d8f3038SAl Viro 19912d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 19921da177e4SLinus Torvalds putname(tmp); 19932d8f3038SAl Viro if (!err) 19942d8f3038SAl Viro *path = nd.path; 19951da177e4SLinus Torvalds } 19961da177e4SLinus Torvalds return err; 19971da177e4SLinus Torvalds } 19981da177e4SLinus Torvalds 19991fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 20001fa1e7f6SAndy Whitcroft struct path *path) 20011fa1e7f6SAndy Whitcroft { 2002f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 20031fa1e7f6SAndy Whitcroft } 20041fa1e7f6SAndy Whitcroft 20052ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 20062ad94ae6SAl Viro struct nameidata *nd, char **name) 20072ad94ae6SAl Viro { 20082ad94ae6SAl Viro char *s = getname(path); 20092ad94ae6SAl Viro int error; 20102ad94ae6SAl Viro 20112ad94ae6SAl Viro if (IS_ERR(s)) 20122ad94ae6SAl Viro return PTR_ERR(s); 20132ad94ae6SAl Viro 20142ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 20152ad94ae6SAl Viro if (error) 20162ad94ae6SAl Viro putname(s); 20172ad94ae6SAl Viro else 20182ad94ae6SAl Viro *name = s; 20192ad94ae6SAl Viro 20202ad94ae6SAl Viro return error; 20212ad94ae6SAl Viro } 20222ad94ae6SAl Viro 20231da177e4SLinus Torvalds /* 20241da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 20251da177e4SLinus Torvalds * minimal. 20261da177e4SLinus Torvalds */ 20271da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 20281da177e4SLinus Torvalds { 20298e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2030da9592edSDavid Howells 20311da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 20321da177e4SLinus Torvalds return 0; 20338e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 20341da177e4SLinus Torvalds return 0; 20358e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 20361da177e4SLinus Torvalds return 0; 20371a48e2acSEric W. Biederman return !inode_capable(inode, CAP_FOWNER); 20381da177e4SLinus Torvalds } 20391da177e4SLinus Torvalds 20401da177e4SLinus Torvalds /* 20411da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 20421da177e4SLinus Torvalds * whether the type of victim is right. 20431da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 20441da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 20451da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 20461da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 20471da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 20481da177e4SLinus Torvalds * a. be owner of dir, or 20491da177e4SLinus Torvalds * b. be owner of victim, or 20501da177e4SLinus Torvalds * c. have CAP_FOWNER capability 20511da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 20521da177e4SLinus Torvalds * links pointing to it. 20531da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 20541da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 20551da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 20561da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 20571da177e4SLinus Torvalds * nfs_async_unlink(). 20581da177e4SLinus Torvalds */ 2059858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 20601da177e4SLinus Torvalds { 20611da177e4SLinus Torvalds int error; 20621da177e4SLinus Torvalds 20631da177e4SLinus Torvalds if (!victim->d_inode) 20641da177e4SLinus Torvalds return -ENOENT; 20651da177e4SLinus Torvalds 20661da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 2067cccc6bbaSAl Viro audit_inode_child(victim, dir); 20681da177e4SLinus Torvalds 2069f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 20701da177e4SLinus Torvalds if (error) 20711da177e4SLinus Torvalds return error; 20721da177e4SLinus Torvalds if (IS_APPEND(dir)) 20731da177e4SLinus Torvalds return -EPERM; 20741da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 2075f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 20761da177e4SLinus Torvalds return -EPERM; 20771da177e4SLinus Torvalds if (isdir) { 20781da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 20791da177e4SLinus Torvalds return -ENOTDIR; 20801da177e4SLinus Torvalds if (IS_ROOT(victim)) 20811da177e4SLinus Torvalds return -EBUSY; 20821da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 20831da177e4SLinus Torvalds return -EISDIR; 20841da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 20851da177e4SLinus Torvalds return -ENOENT; 20861da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 20871da177e4SLinus Torvalds return -EBUSY; 20881da177e4SLinus Torvalds return 0; 20891da177e4SLinus Torvalds } 20901da177e4SLinus Torvalds 20911da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 20921da177e4SLinus Torvalds * dir. 20931da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 20941da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 20951da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 20961da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 20971da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 20981da177e4SLinus Torvalds */ 2099a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 21001da177e4SLinus Torvalds { 21011da177e4SLinus Torvalds if (child->d_inode) 21021da177e4SLinus Torvalds return -EEXIST; 21031da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 21041da177e4SLinus Torvalds return -ENOENT; 2105f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 21061da177e4SLinus Torvalds } 21071da177e4SLinus Torvalds 21081da177e4SLinus Torvalds /* 21091da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 21101da177e4SLinus Torvalds */ 21111da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 21121da177e4SLinus Torvalds { 21131da177e4SLinus Torvalds struct dentry *p; 21141da177e4SLinus Torvalds 21151da177e4SLinus Torvalds if (p1 == p2) { 2116f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 21171da177e4SLinus Torvalds return NULL; 21181da177e4SLinus Torvalds } 21191da177e4SLinus Torvalds 2120a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 21211da177e4SLinus Torvalds 2122e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2123e2761a11SOGAWA Hirofumi if (p) { 2124f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2125f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 21261da177e4SLinus Torvalds return p; 21271da177e4SLinus Torvalds } 21281da177e4SLinus Torvalds 2129e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2130e2761a11SOGAWA Hirofumi if (p) { 2131f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2132f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 21331da177e4SLinus Torvalds return p; 21341da177e4SLinus Torvalds } 21351da177e4SLinus Torvalds 2136f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2137f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 21381da177e4SLinus Torvalds return NULL; 21391da177e4SLinus Torvalds } 21401da177e4SLinus Torvalds 21411da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 21421da177e4SLinus Torvalds { 21431b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 21441da177e4SLinus Torvalds if (p1 != p2) { 21451b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2146a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 21471da177e4SLinus Torvalds } 21481da177e4SLinus Torvalds } 21491da177e4SLinus Torvalds 21504acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2151312b63fbSAl Viro bool want_excl) 21521da177e4SLinus Torvalds { 2153a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 21541da177e4SLinus Torvalds if (error) 21551da177e4SLinus Torvalds return error; 21561da177e4SLinus Torvalds 2157acfa4380SAl Viro if (!dir->i_op->create) 21581da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 21591da177e4SLinus Torvalds mode &= S_IALLUGO; 21601da177e4SLinus Torvalds mode |= S_IFREG; 21611da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 21621da177e4SLinus Torvalds if (error) 21631da177e4SLinus Torvalds return error; 2164312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2165a74574aaSStephen Smalley if (!error) 2166f38aa942SAmy Griffis fsnotify_create(dir, dentry); 21671da177e4SLinus Torvalds return error; 21681da177e4SLinus Torvalds } 21691da177e4SLinus Torvalds 217073d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 21711da177e4SLinus Torvalds { 21723fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 21731da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 21741da177e4SLinus Torvalds int error; 21751da177e4SLinus Torvalds 2176bcda7652SAl Viro /* O_PATH? */ 2177bcda7652SAl Viro if (!acc_mode) 2178bcda7652SAl Viro return 0; 2179bcda7652SAl Viro 21801da177e4SLinus Torvalds if (!inode) 21811da177e4SLinus Torvalds return -ENOENT; 21821da177e4SLinus Torvalds 2183c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2184c8fe8f30SChristoph Hellwig case S_IFLNK: 21851da177e4SLinus Torvalds return -ELOOP; 2186c8fe8f30SChristoph Hellwig case S_IFDIR: 2187c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 21881da177e4SLinus Torvalds return -EISDIR; 2189c8fe8f30SChristoph Hellwig break; 2190c8fe8f30SChristoph Hellwig case S_IFBLK: 2191c8fe8f30SChristoph Hellwig case S_IFCHR: 21923fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 21931da177e4SLinus Torvalds return -EACCES; 2194c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2195c8fe8f30SChristoph Hellwig case S_IFIFO: 2196c8fe8f30SChristoph Hellwig case S_IFSOCK: 21971da177e4SLinus Torvalds flag &= ~O_TRUNC; 2198c8fe8f30SChristoph Hellwig break; 21994a3fd211SDave Hansen } 2200b41572e9SDave Hansen 22013fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2202b41572e9SDave Hansen if (error) 2203b41572e9SDave Hansen return error; 22046146f0d5SMimi Zohar 22051da177e4SLinus Torvalds /* 22061da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 22071da177e4SLinus Torvalds */ 22081da177e4SLinus Torvalds if (IS_APPEND(inode)) { 22098737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 22107715b521SAl Viro return -EPERM; 22111da177e4SLinus Torvalds if (flag & O_TRUNC) 22127715b521SAl Viro return -EPERM; 22131da177e4SLinus Torvalds } 22141da177e4SLinus Torvalds 22151da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 22162e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 22177715b521SAl Viro return -EPERM; 22181da177e4SLinus Torvalds 2219f3c7691eSJ. Bruce Fields return 0; 22207715b521SAl Viro } 22217715b521SAl Viro 2222e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 22237715b521SAl Viro { 2224e1181ee6SJeff Layton struct path *path = &filp->f_path; 22257715b521SAl Viro struct inode *inode = path->dentry->d_inode; 22267715b521SAl Viro int error = get_write_access(inode); 22271da177e4SLinus Torvalds if (error) 22287715b521SAl Viro return error; 22291da177e4SLinus Torvalds /* 22301da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 22311da177e4SLinus Torvalds */ 22321da177e4SLinus Torvalds error = locks_verify_locked(inode); 2233be6d3e56SKentaro Takeda if (!error) 2234ea0d3ab2STetsuo Handa error = security_path_truncate(path); 22351da177e4SLinus Torvalds if (!error) { 22367715b521SAl Viro error = do_truncate(path->dentry, 0, 2237d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2238e1181ee6SJeff Layton filp); 22391da177e4SLinus Torvalds } 22401da177e4SLinus Torvalds put_write_access(inode); 2241acd0c935SMimi Zohar return error; 22421da177e4SLinus Torvalds } 22431da177e4SLinus Torvalds 2244d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2245d57999e1SDave Hansen { 22468a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 22478a5e929dSAl Viro flag--; 2248d57999e1SDave Hansen return flag; 2249d57999e1SDave Hansen } 2250d57999e1SDave Hansen 2251d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2252d18e9008SMiklos Szeredi { 2253d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2254d18e9008SMiklos Szeredi if (error) 2255d18e9008SMiklos Szeredi return error; 2256d18e9008SMiklos Szeredi 2257d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2258d18e9008SMiklos Szeredi if (error) 2259d18e9008SMiklos Szeredi return error; 2260d18e9008SMiklos Szeredi 2261d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2262d18e9008SMiklos Szeredi } 2263d18e9008SMiklos Szeredi 22641acf0af9SDavid Howells /* 22651acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 22661acf0af9SDavid Howells * dentry. 22671acf0af9SDavid Howells * 22681acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 22691acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 22701acf0af9SDavid Howells * 22711acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 22721acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 22731acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 22741acf0af9SDavid Howells * 22751acf0af9SDavid Howells * Returns an error code otherwise. 22761acf0af9SDavid Howells */ 22772675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 227830d90494SAl Viro struct path *path, struct file *file, 2279015c3bbcSMiklos Szeredi const struct open_flags *op, 228077d660a8SMiklos Szeredi bool *want_write, bool need_lookup, 228147237687SAl Viro int *opened) 2282d18e9008SMiklos Szeredi { 2283d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2284d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2285d18e9008SMiklos Szeredi umode_t mode; 2286d18e9008SMiklos Szeredi int error; 2287d18e9008SMiklos Szeredi int acc_mode; 2288d18e9008SMiklos Szeredi int create_error = 0; 2289d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2290d18e9008SMiklos Szeredi 2291d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2292d18e9008SMiklos Szeredi 2293d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2294d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 22952675a4ebSAl Viro error = -ENOENT; 2296d18e9008SMiklos Szeredi goto out; 2297d18e9008SMiklos Szeredi } 2298d18e9008SMiklos Szeredi 2299d18e9008SMiklos Szeredi mode = op->mode & S_IALLUGO; 2300d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2301d18e9008SMiklos Szeredi mode &= ~current_umask(); 2302d18e9008SMiklos Szeredi 2303d18e9008SMiklos Szeredi if (open_flag & O_EXCL) { 2304d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 230547237687SAl Viro *opened |= FILE_CREATED; 2306d18e9008SMiklos Szeredi } 2307d18e9008SMiklos Szeredi 2308d18e9008SMiklos Szeredi /* 2309d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2310d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2311d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2312d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2313d18e9008SMiklos Szeredi * 2314d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2315d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2316d18e9008SMiklos Szeredi */ 2317d18e9008SMiklos Szeredi if ((open_flag & (O_CREAT | O_TRUNC)) || 2318d18e9008SMiklos Szeredi (open_flag & O_ACCMODE) != O_RDONLY) { 2319d18e9008SMiklos Szeredi error = mnt_want_write(nd->path.mnt); 2320d18e9008SMiklos Szeredi if (!error) { 232177d660a8SMiklos Szeredi *want_write = true; 2322d18e9008SMiklos Szeredi } else if (!(open_flag & O_CREAT)) { 2323d18e9008SMiklos Szeredi /* 2324d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2325d18e9008SMiklos Szeredi * back to lookup + open 2326d18e9008SMiklos Szeredi */ 2327d18e9008SMiklos Szeredi goto no_open; 2328d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2329d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 2330d18e9008SMiklos Szeredi create_error = error; 2331d18e9008SMiklos Szeredi goto no_open; 2332d18e9008SMiklos Szeredi } else { 2333d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 2334d18e9008SMiklos Szeredi create_error = error; 2335d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2336d18e9008SMiklos Szeredi } 2337d18e9008SMiklos Szeredi } 2338d18e9008SMiklos Szeredi 2339d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 2340d18e9008SMiklos Szeredi error = may_o_create(&nd->path, dentry, op->mode); 2341d18e9008SMiklos Szeredi if (error) { 2342d18e9008SMiklos Szeredi create_error = error; 2343d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2344d18e9008SMiklos Szeredi goto no_open; 2345d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2346d18e9008SMiklos Szeredi } 2347d18e9008SMiklos Szeredi } 2348d18e9008SMiklos Szeredi 2349d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2350d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2351d18e9008SMiklos Szeredi 235230d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 235330d90494SAl Viro file->f_path.mnt = nd->path.mnt; 235430d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 235547237687SAl Viro opened); 2356d9585277SAl Viro if (error < 0) { 2357d9585277SAl Viro if (create_error && error == -ENOENT) 2358d9585277SAl Viro error = create_error; 2359d18e9008SMiklos Szeredi goto out; 2360d18e9008SMiklos Szeredi } 2361d18e9008SMiklos Szeredi 2362d18e9008SMiklos Szeredi acc_mode = op->acc_mode; 236347237687SAl Viro if (*opened & FILE_CREATED) { 2364d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 2365d18e9008SMiklos Szeredi acc_mode = MAY_OPEN; 2366d18e9008SMiklos Szeredi } 2367d18e9008SMiklos Szeredi 2368d9585277SAl Viro if (error) { /* returned 1, that is */ 236930d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 23702675a4ebSAl Viro error = -EIO; 2371d18e9008SMiklos Szeredi goto out; 2372d18e9008SMiklos Szeredi } 237330d90494SAl Viro if (file->f_path.dentry) { 2374d18e9008SMiklos Szeredi dput(dentry); 237530d90494SAl Viro dentry = file->f_path.dentry; 2376d18e9008SMiklos Szeredi } 2377d18e9008SMiklos Szeredi goto looked_up; 2378d18e9008SMiklos Szeredi } 2379d18e9008SMiklos Szeredi 2380d18e9008SMiklos Szeredi /* 2381d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2382d18e9008SMiklos Szeredi * here. 2383d18e9008SMiklos Szeredi */ 23842675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 23852675a4ebSAl Viro if (error) 23862675a4ebSAl Viro fput(file); 2387d18e9008SMiklos Szeredi 2388d18e9008SMiklos Szeredi out: 2389d18e9008SMiklos Szeredi dput(dentry); 23902675a4ebSAl Viro return error; 2391d18e9008SMiklos Szeredi 2392d18e9008SMiklos Szeredi no_open: 2393d18e9008SMiklos Szeredi if (need_lookup) { 239472bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2395d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 23962675a4ebSAl Viro return PTR_ERR(dentry); 2397d18e9008SMiklos Szeredi 2398d18e9008SMiklos Szeredi if (create_error) { 2399d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2400d18e9008SMiklos Szeredi 24012675a4ebSAl Viro error = create_error; 2402d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2403d18e9008SMiklos Szeredi if (!dentry->d_inode) 2404d18e9008SMiklos Szeredi goto out; 2405d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2406d18e9008SMiklos Szeredi goto out; 2407d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2408d18e9008SMiklos Szeredi S_ISREG(dentry->d_inode->i_mode)) { 2409d18e9008SMiklos Szeredi goto out; 2410d18e9008SMiklos Szeredi } 2411d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2412d18e9008SMiklos Szeredi } 2413d18e9008SMiklos Szeredi } 2414d18e9008SMiklos Szeredi looked_up: 2415d18e9008SMiklos Szeredi path->dentry = dentry; 2416d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 24172675a4ebSAl Viro return 1; 2418d18e9008SMiklos Szeredi } 2419d18e9008SMiklos Szeredi 242031e6b01fSNick Piggin /* 24211acf0af9SDavid Howells * Look up and maybe create and open the last component. 2422d58ffd35SMiklos Szeredi * 2423d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2424d58ffd35SMiklos Szeredi * 24251acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 24261acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 24271acf0af9SDavid Howells * 24281acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 24291acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 24301acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 24311acf0af9SDavid Howells * specified then a negative dentry may be returned. 24321acf0af9SDavid Howells * 24331acf0af9SDavid Howells * An error code is returned otherwise. 24341acf0af9SDavid Howells * 24351acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 24361acf0af9SDavid Howells * cleared otherwise prior to returning. 2437d58ffd35SMiklos Szeredi */ 24382675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 243930d90494SAl Viro struct file *file, 2440d58ffd35SMiklos Szeredi const struct open_flags *op, 244147237687SAl Viro bool *want_write, int *opened) 2442d58ffd35SMiklos Szeredi { 2443d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 244454ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2445d58ffd35SMiklos Szeredi struct dentry *dentry; 2446d58ffd35SMiklos Szeredi int error; 244754ef4872SMiklos Szeredi bool need_lookup; 2448d58ffd35SMiklos Szeredi 244947237687SAl Viro *opened &= ~FILE_CREATED; 2450201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2451d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 24522675a4ebSAl Viro return PTR_ERR(dentry); 2453d58ffd35SMiklos Szeredi 2454d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2455d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2456d18e9008SMiklos Szeredi goto out_no_open; 2457d18e9008SMiklos Szeredi 2458d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 245930d90494SAl Viro return atomic_open(nd, dentry, path, file, op, want_write, 246047237687SAl Viro need_lookup, opened); 2461d18e9008SMiklos Szeredi } 2462d18e9008SMiklos Szeredi 246354ef4872SMiklos Szeredi if (need_lookup) { 246454ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 246554ef4872SMiklos Szeredi 246672bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 246754ef4872SMiklos Szeredi if (IS_ERR(dentry)) 24682675a4ebSAl Viro return PTR_ERR(dentry); 246954ef4872SMiklos Szeredi } 247054ef4872SMiklos Szeredi 2471d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2472d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2473d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2474d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2475d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2476d58ffd35SMiklos Szeredi /* 2477d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2478d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2479d58ffd35SMiklos Szeredi * the time when the file is created and when 2480d58ffd35SMiklos Szeredi * a permanent write count is taken through 2481015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 2482d58ffd35SMiklos Szeredi */ 2483d58ffd35SMiklos Szeredi error = mnt_want_write(nd->path.mnt); 2484d58ffd35SMiklos Szeredi if (error) 2485d58ffd35SMiklos Szeredi goto out_dput; 248677d660a8SMiklos Szeredi *want_write = true; 248747237687SAl Viro *opened |= FILE_CREATED; 2488d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2489d58ffd35SMiklos Szeredi if (error) 2490d58ffd35SMiklos Szeredi goto out_dput; 2491312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 2492312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 2493d58ffd35SMiklos Szeredi if (error) 2494d58ffd35SMiklos Szeredi goto out_dput; 2495d58ffd35SMiklos Szeredi } 2496d18e9008SMiklos Szeredi out_no_open: 2497d58ffd35SMiklos Szeredi path->dentry = dentry; 2498d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 24992675a4ebSAl Viro return 1; 2500d58ffd35SMiklos Szeredi 2501d58ffd35SMiklos Szeredi out_dput: 2502d58ffd35SMiklos Szeredi dput(dentry); 25032675a4ebSAl Viro return error; 2504d58ffd35SMiklos Szeredi } 2505d58ffd35SMiklos Szeredi 2506d58ffd35SMiklos Szeredi /* 2507fe2d35ffSAl Viro * Handle the last step of open() 250831e6b01fSNick Piggin */ 25092675a4ebSAl Viro static int do_last(struct nameidata *nd, struct path *path, 251030d90494SAl Viro struct file *file, const struct open_flags *op, 251147237687SAl Viro int *opened, const char *pathname) 2512fb1cc555SAl Viro { 2513a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2514ca344a89SAl Viro int open_flag = op->open_flag; 251577d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 251677d660a8SMiklos Szeredi bool want_write = false; 2517bcda7652SAl Viro int acc_mode = op->acc_mode; 2518a1eb3315SMiklos Szeredi struct inode *inode; 251977d660a8SMiklos Szeredi bool symlink_ok = false; 252016b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 252116b1c1cdSMiklos Szeredi bool retried = false; 252216c2cd71SAl Viro int error; 2523fb1cc555SAl Viro 2524c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2525c3e380b0SAl Viro nd->flags |= op->intent; 2526c3e380b0SAl Viro 25271f36f774SAl Viro switch (nd->last_type) { 25281f36f774SAl Viro case LAST_DOTDOT: 2529176306f5SNeil Brown case LAST_DOT: 2530fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2531fe2d35ffSAl Viro if (error) 25322675a4ebSAl Viro return error; 25331f36f774SAl Viro /* fallthrough */ 25341f36f774SAl Viro case LAST_ROOT: 25359f1fafeeSAl Viro error = complete_walk(nd); 253616c2cd71SAl Viro if (error) 25372675a4ebSAl Viro return error; 2538fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2539ca344a89SAl Viro if (open_flag & O_CREAT) { 254016c2cd71SAl Viro error = -EISDIR; 25412675a4ebSAl Viro goto out; 2542fe2d35ffSAl Viro } 2543e83db167SMiklos Szeredi goto finish_open; 25441f36f774SAl Viro case LAST_BIND: 25459f1fafeeSAl Viro error = complete_walk(nd); 254616c2cd71SAl Viro if (error) 25472675a4ebSAl Viro return error; 25481f36f774SAl Viro audit_inode(pathname, dir); 2549e83db167SMiklos Szeredi goto finish_open; 25501f36f774SAl Viro } 2551a2c36b45SAl Viro 2552ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2553fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2554fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2555bcda7652SAl Viro if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) 255677d660a8SMiklos Szeredi symlink_ok = true; 2557fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2558a1eb3315SMiklos Szeredi error = lookup_fast(nd, &nd->last, path, &inode); 255971574865SMiklos Szeredi if (likely(!error)) 256071574865SMiklos Szeredi goto finish_lookup; 256171574865SMiklos Szeredi 2562ce57dfc1SAl Viro if (error < 0) 25632675a4ebSAl Viro goto out; 2564a1eb3315SMiklos Szeredi 256537d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 2566b6183df7SMiklos Szeredi } else { 2567fe2d35ffSAl Viro /* create side of things */ 2568a3fbbde7SAl Viro /* 2569b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 2570b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 2571b6183df7SMiklos Szeredi * about to look up 2572a3fbbde7SAl Viro */ 25739f1fafeeSAl Viro error = complete_walk(nd); 25749f1fafeeSAl Viro if (error) 25752675a4ebSAl Viro return error; 2576fe2d35ffSAl Viro 2577fe2d35ffSAl Viro audit_inode(pathname, dir); 257816c2cd71SAl Viro error = -EISDIR; 25791f36f774SAl Viro /* trailing slashes? */ 258031e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 25812675a4ebSAl Viro goto out; 2582b6183df7SMiklos Szeredi } 25831f36f774SAl Viro 258416b1c1cdSMiklos Szeredi retry_lookup: 2585a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 25862675a4ebSAl Viro error = lookup_open(nd, path, file, op, &want_write, opened); 2587fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2588fb1cc555SAl Viro 25892675a4ebSAl Viro if (error <= 0) { 25902675a4ebSAl Viro if (error) 2591d58ffd35SMiklos Szeredi goto out; 25926c0d46c4SAl Viro 259347237687SAl Viro if ((*opened & FILE_CREATED) || 25942675a4ebSAl Viro !S_ISREG(file->f_path.dentry->d_inode->i_mode)) 259577d660a8SMiklos Szeredi will_truncate = false; 2596d18e9008SMiklos Szeredi 25972675a4ebSAl Viro audit_inode(pathname, file->f_path.dentry); 2598d18e9008SMiklos Szeredi goto opened; 2599d18e9008SMiklos Szeredi } 2600d18e9008SMiklos Szeredi 260147237687SAl Viro if (*opened & FILE_CREATED) { 26029b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 2603ca344a89SAl Viro open_flag &= ~O_TRUNC; 260477d660a8SMiklos Szeredi will_truncate = false; 2605bcda7652SAl Viro acc_mode = MAY_OPEN; 2606d58ffd35SMiklos Szeredi path_to_nameidata(path, nd); 2607e83db167SMiklos Szeredi goto finish_open_created; 2608fb1cc555SAl Viro } 2609fb1cc555SAl Viro 2610fb1cc555SAl Viro /* 2611fb1cc555SAl Viro * It already exists. 2612fb1cc555SAl Viro */ 2613fb1cc555SAl Viro audit_inode(pathname, path->dentry); 2614fb1cc555SAl Viro 2615d18e9008SMiklos Szeredi /* 2616d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 2617d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 2618d18e9008SMiklos Szeredi * necessary...) 2619d18e9008SMiklos Szeredi */ 2620d18e9008SMiklos Szeredi if (want_write) { 2621d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 262277d660a8SMiklos Szeredi want_write = false; 2623d18e9008SMiklos Szeredi } 2624d18e9008SMiklos Szeredi 2625fb1cc555SAl Viro error = -EEXIST; 2626ca344a89SAl Viro if (open_flag & O_EXCL) 2627fb1cc555SAl Viro goto exit_dput; 2628fb1cc555SAl Viro 26299875cf80SDavid Howells error = follow_managed(path, nd->flags); 26309875cf80SDavid Howells if (error < 0) 2631fb1cc555SAl Viro goto exit_dput; 2632fb1cc555SAl Viro 2633a3fbbde7SAl Viro if (error) 2634a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 2635a3fbbde7SAl Viro 2636decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 2637decf3400SMiklos Szeredi inode = path->dentry->d_inode; 26385f5daac1SMiklos Szeredi finish_lookup: 26395f5daac1SMiklos Szeredi /* we _can_ be in RCU mode here */ 2640fb1cc555SAl Viro error = -ENOENT; 264154c33e7fSMiklos Szeredi if (!inode) { 264254c33e7fSMiklos Szeredi path_to_nameidata(path, nd); 26432675a4ebSAl Viro goto out; 264454c33e7fSMiklos Szeredi } 26459e67f361SAl Viro 2646d45ea867SMiklos Szeredi if (should_follow_link(inode, !symlink_ok)) { 2647d45ea867SMiklos Szeredi if (nd->flags & LOOKUP_RCU) { 2648d45ea867SMiklos Szeredi if (unlikely(unlazy_walk(nd, path->dentry))) { 2649d45ea867SMiklos Szeredi error = -ECHILD; 26502675a4ebSAl Viro goto out; 2651d45ea867SMiklos Szeredi } 2652d45ea867SMiklos Szeredi } 2653d45ea867SMiklos Szeredi BUG_ON(inode != path->dentry->d_inode); 26542675a4ebSAl Viro return 1; 2655d45ea867SMiklos Szeredi } 2656fb1cc555SAl Viro 265716b1c1cdSMiklos Szeredi if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path->mnt) { 2658fb1cc555SAl Viro path_to_nameidata(path, nd); 265916b1c1cdSMiklos Szeredi } else { 266016b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 266116b1c1cdSMiklos Szeredi save_parent.mnt = mntget(path->mnt); 266216b1c1cdSMiklos Szeredi nd->path.dentry = path->dentry; 266316b1c1cdSMiklos Szeredi 266416b1c1cdSMiklos Szeredi } 2665decf3400SMiklos Szeredi nd->inode = inode; 2666a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 2667a3fbbde7SAl Viro error = complete_walk(nd); 266816b1c1cdSMiklos Szeredi if (error) { 266916b1c1cdSMiklos Szeredi path_put(&save_parent); 26702675a4ebSAl Viro return error; 267116b1c1cdSMiklos Szeredi } 2672fb1cc555SAl Viro error = -EISDIR; 2673050ac841SMiklos Szeredi if ((open_flag & O_CREAT) && S_ISDIR(nd->inode->i_mode)) 26742675a4ebSAl Viro goto out; 2675af2f5542SMiklos Szeredi error = -ENOTDIR; 2676af2f5542SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !nd->inode->i_op->lookup) 26772675a4ebSAl Viro goto out; 2678d7fdd7f6SMiklos Szeredi audit_inode(pathname, nd->path.dentry); 2679e83db167SMiklos Szeredi finish_open: 26806c0d46c4SAl Viro if (!S_ISREG(nd->inode->i_mode)) 268177d660a8SMiklos Szeredi will_truncate = false; 26826c0d46c4SAl Viro 26830f9d1a10SAl Viro if (will_truncate) { 26840f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 26850f9d1a10SAl Viro if (error) 26862675a4ebSAl Viro goto out; 268777d660a8SMiklos Szeredi want_write = true; 26880f9d1a10SAl Viro } 2689e83db167SMiklos Szeredi finish_open_created: 2690bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 2691ca344a89SAl Viro if (error) 26922675a4ebSAl Viro goto out; 269330d90494SAl Viro file->f_path.mnt = nd->path.mnt; 269430d90494SAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 269530d90494SAl Viro if (error) { 269630d90494SAl Viro if (error == -EOPENSTALE) 2697f60dc3dbSMiklos Szeredi goto stale_open; 2698015c3bbcSMiklos Szeredi goto out; 2699f60dc3dbSMiklos Szeredi } 2700a8277b9bSMiklos Szeredi opened: 27012675a4ebSAl Viro error = open_check_o_direct(file); 2702015c3bbcSMiklos Szeredi if (error) 2703015c3bbcSMiklos Szeredi goto exit_fput; 27042675a4ebSAl Viro error = ima_file_check(file, op->acc_mode); 2705aa4caadbSMiklos Szeredi if (error) 2706aa4caadbSMiklos Szeredi goto exit_fput; 2707aa4caadbSMiklos Szeredi 27080f9d1a10SAl Viro if (will_truncate) { 27092675a4ebSAl Viro error = handle_truncate(file); 2710aa4caadbSMiklos Szeredi if (error) 2711aa4caadbSMiklos Szeredi goto exit_fput; 27120f9d1a10SAl Viro } 2713ca344a89SAl Viro out: 2714ca344a89SAl Viro if (want_write) 27150f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 271616b1c1cdSMiklos Szeredi path_put(&save_parent); 2717e276ae67SMiklos Szeredi terminate_walk(nd); 27182675a4ebSAl Viro return error; 2719fb1cc555SAl Viro 2720fb1cc555SAl Viro exit_dput: 2721fb1cc555SAl Viro path_put_conditional(path, nd); 2722ca344a89SAl Viro goto out; 2723015c3bbcSMiklos Szeredi exit_fput: 27242675a4ebSAl Viro fput(file); 27252675a4ebSAl Viro goto out; 2726015c3bbcSMiklos Szeredi 2727f60dc3dbSMiklos Szeredi stale_open: 2728f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 2729f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 2730f60dc3dbSMiklos Szeredi goto out; 2731f60dc3dbSMiklos Szeredi 2732f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 2733f60dc3dbSMiklos Szeredi path_put(&nd->path); 2734f60dc3dbSMiklos Szeredi nd->path = save_parent; 2735f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 2736f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 2737f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 2738f60dc3dbSMiklos Szeredi if (want_write) { 2739f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 2740f60dc3dbSMiklos Szeredi want_write = false; 2741f60dc3dbSMiklos Szeredi } 2742f60dc3dbSMiklos Szeredi retried = true; 2743f60dc3dbSMiklos Szeredi goto retry_lookup; 2744fb1cc555SAl Viro } 2745fb1cc555SAl Viro 274613aab428SAl Viro static struct file *path_openat(int dfd, const char *pathname, 274773d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 27481da177e4SLinus Torvalds { 2749fe2d35ffSAl Viro struct file *base = NULL; 275030d90494SAl Viro struct file *file; 27519850c056SAl Viro struct path path; 275247237687SAl Viro int opened = 0; 275313aab428SAl Viro int error; 275431e6b01fSNick Piggin 275530d90494SAl Viro file = get_empty_filp(); 275630d90494SAl Viro if (!file) 275731e6b01fSNick Piggin return ERR_PTR(-ENFILE); 275831e6b01fSNick Piggin 275930d90494SAl Viro file->f_flags = op->open_flag; 276031e6b01fSNick Piggin 276173d049a4SAl Viro error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base); 276231e6b01fSNick Piggin if (unlikely(error)) 27632675a4ebSAl Viro goto out; 276431e6b01fSNick Piggin 2765fe2d35ffSAl Viro current->total_link_count = 0; 276673d049a4SAl Viro error = link_path_walk(pathname, nd); 276731e6b01fSNick Piggin if (unlikely(error)) 27682675a4ebSAl Viro goto out; 27691da177e4SLinus Torvalds 27702675a4ebSAl Viro error = do_last(nd, &path, file, op, &opened, pathname); 27712675a4ebSAl Viro while (unlikely(error > 0)) { /* trailing symlink */ 27727b9337aaSNick Piggin struct path link = path; 2773def4af30SAl Viro void *cookie; 2774574197e0SAl Viro if (!(nd->flags & LOOKUP_FOLLOW)) { 277573d049a4SAl Viro path_put_conditional(&path, nd); 277673d049a4SAl Viro path_put(&nd->path); 27772675a4ebSAl Viro error = -ELOOP; 277840b39136SAl Viro break; 277940b39136SAl Viro } 278073d049a4SAl Viro nd->flags |= LOOKUP_PARENT; 278173d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 2782574197e0SAl Viro error = follow_link(&link, nd, &cookie); 2783c3e380b0SAl Viro if (unlikely(error)) 27842675a4ebSAl Viro break; 27852675a4ebSAl Viro error = do_last(nd, &path, file, op, &opened, pathname); 2786574197e0SAl Viro put_link(nd, &link, cookie); 2787806b681cSAl Viro } 278810fa8e62SAl Viro out: 278973d049a4SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) 279073d049a4SAl Viro path_put(&nd->root); 2791fe2d35ffSAl Viro if (base) 2792fe2d35ffSAl Viro fput(base); 27932675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 27942675a4ebSAl Viro BUG_ON(!error); 279530d90494SAl Viro put_filp(file); 2796015c3bbcSMiklos Szeredi } 27972675a4ebSAl Viro if (unlikely(error)) { 27982675a4ebSAl Viro if (error == -EOPENSTALE) { 27992675a4ebSAl Viro if (flags & LOOKUP_RCU) 28002675a4ebSAl Viro error = -ECHILD; 28012675a4ebSAl Viro else 28022675a4ebSAl Viro error = -ESTALE; 28032675a4ebSAl Viro } 28042675a4ebSAl Viro file = ERR_PTR(error); 28052675a4ebSAl Viro } 28062675a4ebSAl Viro return file; 2807de459215SKirill Korotaev } 28081da177e4SLinus Torvalds 280913aab428SAl Viro struct file *do_filp_open(int dfd, const char *pathname, 281013aab428SAl Viro const struct open_flags *op, int flags) 281113aab428SAl Viro { 281273d049a4SAl Viro struct nameidata nd; 281313aab428SAl Viro struct file *filp; 281413aab428SAl Viro 281573d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 281613aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 281773d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 281813aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 281973d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 282013aab428SAl Viro return filp; 282113aab428SAl Viro } 282213aab428SAl Viro 282373d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 282473d049a4SAl Viro const char *name, const struct open_flags *op, int flags) 282573d049a4SAl Viro { 282673d049a4SAl Viro struct nameidata nd; 282773d049a4SAl Viro struct file *file; 282873d049a4SAl Viro 282973d049a4SAl Viro nd.root.mnt = mnt; 283073d049a4SAl Viro nd.root.dentry = dentry; 283173d049a4SAl Viro 283273d049a4SAl Viro flags |= LOOKUP_ROOT; 283373d049a4SAl Viro 2834bcda7652SAl Viro if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) 283573d049a4SAl Viro return ERR_PTR(-ELOOP); 283673d049a4SAl Viro 283773d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU); 283873d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 283973d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags); 284073d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 284173d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL); 284273d049a4SAl Viro return file; 284373d049a4SAl Viro } 284473d049a4SAl Viro 2845ed75e95dSAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, int is_dir) 28461da177e4SLinus Torvalds { 2847c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 2848ed75e95dSAl Viro struct nameidata nd; 2849ed75e95dSAl Viro int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd); 2850ed75e95dSAl Viro if (error) 2851ed75e95dSAl Viro return ERR_PTR(error); 28521da177e4SLinus Torvalds 2853c663e5d8SChristoph Hellwig /* 2854c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 2855c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 2856c663e5d8SChristoph Hellwig */ 2857ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 2858ed75e95dSAl Viro goto out; 2859ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 2860ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 2861c663e5d8SChristoph Hellwig 2862c663e5d8SChristoph Hellwig /* 2863c663e5d8SChristoph Hellwig * Do the final lookup. 2864c663e5d8SChristoph Hellwig */ 2865ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 2866ed75e95dSAl Viro dentry = lookup_hash(&nd); 28671da177e4SLinus Torvalds if (IS_ERR(dentry)) 28681da177e4SLinus Torvalds goto fail; 2869c663e5d8SChristoph Hellwig 2870e9baf6e5SAl Viro if (dentry->d_inode) 2871e9baf6e5SAl Viro goto eexist; 2872c663e5d8SChristoph Hellwig /* 2873c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 2874c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 2875c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 2876c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 2877c663e5d8SChristoph Hellwig */ 2878ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 28791da177e4SLinus Torvalds dput(dentry); 28801da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 2881ed75e95dSAl Viro goto fail; 2882e9baf6e5SAl Viro } 2883ed75e95dSAl Viro *path = nd.path; 2884e9baf6e5SAl Viro return dentry; 2885e9baf6e5SAl Viro eexist: 2886e9baf6e5SAl Viro dput(dentry); 2887e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 28881da177e4SLinus Torvalds fail: 2889dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 2890ed75e95dSAl Viro out: 2891dae6ad8fSAl Viro path_put(&nd.path); 2892ed75e95dSAl Viro return dentry; 2893dae6ad8fSAl Viro } 2894dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 2895dae6ad8fSAl Viro 2896921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 2897921a1650SAl Viro { 2898921a1650SAl Viro dput(dentry); 2899921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 2900921a1650SAl Viro path_put(path); 2901921a1650SAl Viro } 2902921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 2903921a1650SAl Viro 2904dae6ad8fSAl Viro struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, int is_dir) 2905dae6ad8fSAl Viro { 2906dae6ad8fSAl Viro char *tmp = getname(pathname); 2907dae6ad8fSAl Viro struct dentry *res; 2908dae6ad8fSAl Viro if (IS_ERR(tmp)) 2909dae6ad8fSAl Viro return ERR_CAST(tmp); 2910dae6ad8fSAl Viro res = kern_path_create(dfd, tmp, path, is_dir); 2911dae6ad8fSAl Viro putname(tmp); 2912dae6ad8fSAl Viro return res; 2913dae6ad8fSAl Viro } 2914dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 2915dae6ad8fSAl Viro 29161a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 29171da177e4SLinus Torvalds { 2918a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 29191da177e4SLinus Torvalds 29201da177e4SLinus Torvalds if (error) 29211da177e4SLinus Torvalds return error; 29221da177e4SLinus Torvalds 2923975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 29241da177e4SLinus Torvalds return -EPERM; 29251da177e4SLinus Torvalds 2926acfa4380SAl Viro if (!dir->i_op->mknod) 29271da177e4SLinus Torvalds return -EPERM; 29281da177e4SLinus Torvalds 292908ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 293008ce5f16SSerge E. Hallyn if (error) 293108ce5f16SSerge E. Hallyn return error; 293208ce5f16SSerge E. Hallyn 29331da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 29341da177e4SLinus Torvalds if (error) 29351da177e4SLinus Torvalds return error; 29361da177e4SLinus Torvalds 29371da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 2938a74574aaSStephen Smalley if (!error) 2939f38aa942SAmy Griffis fsnotify_create(dir, dentry); 29401da177e4SLinus Torvalds return error; 29411da177e4SLinus Torvalds } 29421da177e4SLinus Torvalds 2943f69aac00SAl Viro static int may_mknod(umode_t mode) 2944463c3197SDave Hansen { 2945463c3197SDave Hansen switch (mode & S_IFMT) { 2946463c3197SDave Hansen case S_IFREG: 2947463c3197SDave Hansen case S_IFCHR: 2948463c3197SDave Hansen case S_IFBLK: 2949463c3197SDave Hansen case S_IFIFO: 2950463c3197SDave Hansen case S_IFSOCK: 2951463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 2952463c3197SDave Hansen return 0; 2953463c3197SDave Hansen case S_IFDIR: 2954463c3197SDave Hansen return -EPERM; 2955463c3197SDave Hansen default: 2956463c3197SDave Hansen return -EINVAL; 2957463c3197SDave Hansen } 2958463c3197SDave Hansen } 2959463c3197SDave Hansen 29608208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 29612e4d0924SHeiko Carstens unsigned, dev) 29621da177e4SLinus Torvalds { 29631da177e4SLinus Torvalds struct dentry *dentry; 2964dae6ad8fSAl Viro struct path path; 2965dae6ad8fSAl Viro int error; 29661da177e4SLinus Torvalds 29671da177e4SLinus Torvalds if (S_ISDIR(mode)) 29681da177e4SLinus Torvalds return -EPERM; 29691da177e4SLinus Torvalds 2970dae6ad8fSAl Viro dentry = user_path_create(dfd, filename, &path, 0); 2971dae6ad8fSAl Viro if (IS_ERR(dentry)) 2972dae6ad8fSAl Viro return PTR_ERR(dentry); 29732ad94ae6SAl Viro 2974dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 2975ce3b0f8dSAl Viro mode &= ~current_umask(); 2976463c3197SDave Hansen error = may_mknod(mode); 2977463c3197SDave Hansen if (error) 2978463c3197SDave Hansen goto out_dput; 2979dae6ad8fSAl Viro error = mnt_want_write(path.mnt); 2980463c3197SDave Hansen if (error) 2981463c3197SDave Hansen goto out_dput; 2982dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 2983be6d3e56SKentaro Takeda if (error) 2984be6d3e56SKentaro Takeda goto out_drop_write; 29851da177e4SLinus Torvalds switch (mode & S_IFMT) { 29861da177e4SLinus Torvalds case 0: case S_IFREG: 2987312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 29881da177e4SLinus Torvalds break; 29891da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 2990dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 29911da177e4SLinus Torvalds new_decode_dev(dev)); 29921da177e4SLinus Torvalds break; 29931da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 2994dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 29951da177e4SLinus Torvalds break; 29961da177e4SLinus Torvalds } 2997be6d3e56SKentaro Takeda out_drop_write: 2998dae6ad8fSAl Viro mnt_drop_write(path.mnt); 2999463c3197SDave Hansen out_dput: 3000921a1650SAl Viro done_path_create(&path, dentry); 30011da177e4SLinus Torvalds 30021da177e4SLinus Torvalds return error; 30031da177e4SLinus Torvalds } 30041da177e4SLinus Torvalds 30058208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 30065590ff0dSUlrich Drepper { 30075590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 30085590ff0dSUlrich Drepper } 30095590ff0dSUlrich Drepper 301018bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 30111da177e4SLinus Torvalds { 3012a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 30138de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 30141da177e4SLinus Torvalds 30151da177e4SLinus Torvalds if (error) 30161da177e4SLinus Torvalds return error; 30171da177e4SLinus Torvalds 3018acfa4380SAl Viro if (!dir->i_op->mkdir) 30191da177e4SLinus Torvalds return -EPERM; 30201da177e4SLinus Torvalds 30211da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 30221da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 30231da177e4SLinus Torvalds if (error) 30241da177e4SLinus Torvalds return error; 30251da177e4SLinus Torvalds 30268de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 30278de52778SAl Viro return -EMLINK; 30288de52778SAl Viro 30291da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3030a74574aaSStephen Smalley if (!error) 3031f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 30321da177e4SLinus Torvalds return error; 30331da177e4SLinus Torvalds } 30341da177e4SLinus Torvalds 3035a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 30361da177e4SLinus Torvalds { 30376902d925SDave Hansen struct dentry *dentry; 3038dae6ad8fSAl Viro struct path path; 3039dae6ad8fSAl Viro int error; 30401da177e4SLinus Torvalds 3041dae6ad8fSAl Viro dentry = user_path_create(dfd, pathname, &path, 1); 30426902d925SDave Hansen if (IS_ERR(dentry)) 3043dae6ad8fSAl Viro return PTR_ERR(dentry); 30446902d925SDave Hansen 3045dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3046ce3b0f8dSAl Viro mode &= ~current_umask(); 3047dae6ad8fSAl Viro error = mnt_want_write(path.mnt); 3048463c3197SDave Hansen if (error) 3049463c3197SDave Hansen goto out_dput; 3050dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3051be6d3e56SKentaro Takeda if (error) 3052be6d3e56SKentaro Takeda goto out_drop_write; 3053dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3054be6d3e56SKentaro Takeda out_drop_write: 3055dae6ad8fSAl Viro mnt_drop_write(path.mnt); 3056463c3197SDave Hansen out_dput: 3057921a1650SAl Viro done_path_create(&path, dentry); 30581da177e4SLinus Torvalds return error; 30591da177e4SLinus Torvalds } 30601da177e4SLinus Torvalds 3061a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 30625590ff0dSUlrich Drepper { 30635590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 30645590ff0dSUlrich Drepper } 30655590ff0dSUlrich Drepper 30661da177e4SLinus Torvalds /* 3067a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3068c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3069a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3070a71905f0SSage Weil * then we drop the dentry now. 30711da177e4SLinus Torvalds * 30721da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 30731da177e4SLinus Torvalds * do a 30741da177e4SLinus Torvalds * 30751da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 30761da177e4SLinus Torvalds * return -EBUSY; 30771da177e4SLinus Torvalds * 30781da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 30791da177e4SLinus Torvalds * that is still in use by something else.. 30801da177e4SLinus Torvalds */ 30811da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 30821da177e4SLinus Torvalds { 30831da177e4SLinus Torvalds shrink_dcache_parent(dentry); 30841da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 308564252c75SSage Weil if (dentry->d_count == 1) 30861da177e4SLinus Torvalds __d_drop(dentry); 30871da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 30881da177e4SLinus Torvalds } 30891da177e4SLinus Torvalds 30901da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 30911da177e4SLinus Torvalds { 30921da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 30931da177e4SLinus Torvalds 30941da177e4SLinus Torvalds if (error) 30951da177e4SLinus Torvalds return error; 30961da177e4SLinus Torvalds 3097acfa4380SAl Viro if (!dir->i_op->rmdir) 30981da177e4SLinus Torvalds return -EPERM; 30991da177e4SLinus Torvalds 31001d2ef590SAl Viro dget(dentry); 31011b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3102912dbc15SSage Weil 31031da177e4SLinus Torvalds error = -EBUSY; 3104912dbc15SSage Weil if (d_mountpoint(dentry)) 3105912dbc15SSage Weil goto out; 3106912dbc15SSage Weil 31071da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3108912dbc15SSage Weil if (error) 3109912dbc15SSage Weil goto out; 3110912dbc15SSage Weil 31113cebde24SSage Weil shrink_dcache_parent(dentry); 31121da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3113912dbc15SSage Weil if (error) 3114912dbc15SSage Weil goto out; 3115912dbc15SSage Weil 31161da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3117d83c49f3SAl Viro dont_mount(dentry); 31181da177e4SLinus Torvalds 3119912dbc15SSage Weil out: 3120912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 31211d2ef590SAl Viro dput(dentry); 3122912dbc15SSage Weil if (!error) 3123912dbc15SSage Weil d_delete(dentry); 31241da177e4SLinus Torvalds return error; 31251da177e4SLinus Torvalds } 31261da177e4SLinus Torvalds 31275590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 31281da177e4SLinus Torvalds { 31291da177e4SLinus Torvalds int error = 0; 31301da177e4SLinus Torvalds char * name; 31311da177e4SLinus Torvalds struct dentry *dentry; 31321da177e4SLinus Torvalds struct nameidata nd; 31331da177e4SLinus Torvalds 31342ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 31351da177e4SLinus Torvalds if (error) 31362ad94ae6SAl Viro return error; 31371da177e4SLinus Torvalds 31381da177e4SLinus Torvalds switch(nd.last_type) { 31391da177e4SLinus Torvalds case LAST_DOTDOT: 31401da177e4SLinus Torvalds error = -ENOTEMPTY; 31411da177e4SLinus Torvalds goto exit1; 31421da177e4SLinus Torvalds case LAST_DOT: 31431da177e4SLinus Torvalds error = -EINVAL; 31441da177e4SLinus Torvalds goto exit1; 31451da177e4SLinus Torvalds case LAST_ROOT: 31461da177e4SLinus Torvalds error = -EBUSY; 31471da177e4SLinus Torvalds goto exit1; 31481da177e4SLinus Torvalds } 31490612d9fbSOGAWA Hirofumi 31500612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 31510612d9fbSOGAWA Hirofumi 31524ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 315349705b77SChristoph Hellwig dentry = lookup_hash(&nd); 31541da177e4SLinus Torvalds error = PTR_ERR(dentry); 31556902d925SDave Hansen if (IS_ERR(dentry)) 31566902d925SDave Hansen goto exit2; 3157e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3158e6bc45d6STheodore Ts'o error = -ENOENT; 3159e6bc45d6STheodore Ts'o goto exit3; 3160e6bc45d6STheodore Ts'o } 31610622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 31620622753bSDave Hansen if (error) 31630622753bSDave Hansen goto exit3; 3164be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 3165be6d3e56SKentaro Takeda if (error) 3166be6d3e56SKentaro Takeda goto exit4; 31674ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 3168be6d3e56SKentaro Takeda exit4: 31690622753bSDave Hansen mnt_drop_write(nd.path.mnt); 31700622753bSDave Hansen exit3: 31711da177e4SLinus Torvalds dput(dentry); 31726902d925SDave Hansen exit2: 31734ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 31741da177e4SLinus Torvalds exit1: 31751d957f9bSJan Blunck path_put(&nd.path); 31761da177e4SLinus Torvalds putname(name); 31771da177e4SLinus Torvalds return error; 31781da177e4SLinus Torvalds } 31791da177e4SLinus Torvalds 31803cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 31815590ff0dSUlrich Drepper { 31825590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 31835590ff0dSUlrich Drepper } 31845590ff0dSUlrich Drepper 31851da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 31861da177e4SLinus Torvalds { 31871da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 31881da177e4SLinus Torvalds 31891da177e4SLinus Torvalds if (error) 31901da177e4SLinus Torvalds return error; 31911da177e4SLinus Torvalds 3192acfa4380SAl Viro if (!dir->i_op->unlink) 31931da177e4SLinus Torvalds return -EPERM; 31941da177e4SLinus Torvalds 31951b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 31961da177e4SLinus Torvalds if (d_mountpoint(dentry)) 31971da177e4SLinus Torvalds error = -EBUSY; 31981da177e4SLinus Torvalds else { 31991da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3200bec1052eSAl Viro if (!error) { 32011da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 3202bec1052eSAl Viro if (!error) 3203d83c49f3SAl Viro dont_mount(dentry); 3204bec1052eSAl Viro } 32051da177e4SLinus Torvalds } 32061b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 32071da177e4SLinus Torvalds 32081da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 32091da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 3210ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 32111da177e4SLinus Torvalds d_delete(dentry); 32121da177e4SLinus Torvalds } 32130eeca283SRobert Love 32141da177e4SLinus Torvalds return error; 32151da177e4SLinus Torvalds } 32161da177e4SLinus Torvalds 32171da177e4SLinus Torvalds /* 32181da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 32191b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 32201da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 32211da177e4SLinus Torvalds * while waiting on the I/O. 32221da177e4SLinus Torvalds */ 32235590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 32241da177e4SLinus Torvalds { 32252ad94ae6SAl Viro int error; 32261da177e4SLinus Torvalds char *name; 32271da177e4SLinus Torvalds struct dentry *dentry; 32281da177e4SLinus Torvalds struct nameidata nd; 32291da177e4SLinus Torvalds struct inode *inode = NULL; 32301da177e4SLinus Torvalds 32312ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 32321da177e4SLinus Torvalds if (error) 32332ad94ae6SAl Viro return error; 32342ad94ae6SAl Viro 32351da177e4SLinus Torvalds error = -EISDIR; 32361da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 32371da177e4SLinus Torvalds goto exit1; 32380612d9fbSOGAWA Hirofumi 32390612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 32400612d9fbSOGAWA Hirofumi 32414ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 324249705b77SChristoph Hellwig dentry = lookup_hash(&nd); 32431da177e4SLinus Torvalds error = PTR_ERR(dentry); 32441da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 32451da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 324650338b88STörök Edwin if (nd.last.name[nd.last.len]) 324750338b88STörök Edwin goto slashes; 32481da177e4SLinus Torvalds inode = dentry->d_inode; 324950338b88STörök Edwin if (!inode) 3250e6bc45d6STheodore Ts'o goto slashes; 32517de9c6eeSAl Viro ihold(inode); 32520622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 32530622753bSDave Hansen if (error) 32540622753bSDave Hansen goto exit2; 3255be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 3256be6d3e56SKentaro Takeda if (error) 3257be6d3e56SKentaro Takeda goto exit3; 32584ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 3259be6d3e56SKentaro Takeda exit3: 32600622753bSDave Hansen mnt_drop_write(nd.path.mnt); 32611da177e4SLinus Torvalds exit2: 32621da177e4SLinus Torvalds dput(dentry); 32631da177e4SLinus Torvalds } 32644ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 32651da177e4SLinus Torvalds if (inode) 32661da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 32671da177e4SLinus Torvalds exit1: 32681d957f9bSJan Blunck path_put(&nd.path); 32691da177e4SLinus Torvalds putname(name); 32701da177e4SLinus Torvalds return error; 32711da177e4SLinus Torvalds 32721da177e4SLinus Torvalds slashes: 32731da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 32741da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 32751da177e4SLinus Torvalds goto exit2; 32761da177e4SLinus Torvalds } 32771da177e4SLinus Torvalds 32782e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 32795590ff0dSUlrich Drepper { 32805590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 32815590ff0dSUlrich Drepper return -EINVAL; 32825590ff0dSUlrich Drepper 32835590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 32845590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 32855590ff0dSUlrich Drepper 32865590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 32875590ff0dSUlrich Drepper } 32885590ff0dSUlrich Drepper 32893480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 32905590ff0dSUlrich Drepper { 32915590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 32925590ff0dSUlrich Drepper } 32935590ff0dSUlrich Drepper 3294db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 32951da177e4SLinus Torvalds { 3296a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 32971da177e4SLinus Torvalds 32981da177e4SLinus Torvalds if (error) 32991da177e4SLinus Torvalds return error; 33001da177e4SLinus Torvalds 3301acfa4380SAl Viro if (!dir->i_op->symlink) 33021da177e4SLinus Torvalds return -EPERM; 33031da177e4SLinus Torvalds 33041da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 33051da177e4SLinus Torvalds if (error) 33061da177e4SLinus Torvalds return error; 33071da177e4SLinus Torvalds 33081da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3309a74574aaSStephen Smalley if (!error) 3310f38aa942SAmy Griffis fsnotify_create(dir, dentry); 33111da177e4SLinus Torvalds return error; 33121da177e4SLinus Torvalds } 33131da177e4SLinus Torvalds 33142e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 33152e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 33161da177e4SLinus Torvalds { 33172ad94ae6SAl Viro int error; 33181da177e4SLinus Torvalds char *from; 33196902d925SDave Hansen struct dentry *dentry; 3320dae6ad8fSAl Viro struct path path; 33211da177e4SLinus Torvalds 33221da177e4SLinus Torvalds from = getname(oldname); 33231da177e4SLinus Torvalds if (IS_ERR(from)) 33241da177e4SLinus Torvalds return PTR_ERR(from); 33252ad94ae6SAl Viro 3326dae6ad8fSAl Viro dentry = user_path_create(newdfd, newname, &path, 0); 33271da177e4SLinus Torvalds error = PTR_ERR(dentry); 33286902d925SDave Hansen if (IS_ERR(dentry)) 3329dae6ad8fSAl Viro goto out_putname; 33306902d925SDave Hansen 3331dae6ad8fSAl Viro error = mnt_want_write(path.mnt); 333275c3f29dSDave Hansen if (error) 333375c3f29dSDave Hansen goto out_dput; 3334dae6ad8fSAl Viro error = security_path_symlink(&path, dentry, from); 3335be6d3e56SKentaro Takeda if (error) 3336be6d3e56SKentaro Takeda goto out_drop_write; 3337dae6ad8fSAl Viro error = vfs_symlink(path.dentry->d_inode, dentry, from); 3338be6d3e56SKentaro Takeda out_drop_write: 3339dae6ad8fSAl Viro mnt_drop_write(path.mnt); 334075c3f29dSDave Hansen out_dput: 3341921a1650SAl Viro done_path_create(&path, dentry); 33426902d925SDave Hansen out_putname: 33431da177e4SLinus Torvalds putname(from); 33441da177e4SLinus Torvalds return error; 33451da177e4SLinus Torvalds } 33461da177e4SLinus Torvalds 33473480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 33485590ff0dSUlrich Drepper { 33495590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 33505590ff0dSUlrich Drepper } 33515590ff0dSUlrich Drepper 33521da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 33531da177e4SLinus Torvalds { 33541da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 33558de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 33561da177e4SLinus Torvalds int error; 33571da177e4SLinus Torvalds 33581da177e4SLinus Torvalds if (!inode) 33591da177e4SLinus Torvalds return -ENOENT; 33601da177e4SLinus Torvalds 3361a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 33621da177e4SLinus Torvalds if (error) 33631da177e4SLinus Torvalds return error; 33641da177e4SLinus Torvalds 33651da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 33661da177e4SLinus Torvalds return -EXDEV; 33671da177e4SLinus Torvalds 33681da177e4SLinus Torvalds /* 33691da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 33701da177e4SLinus Torvalds */ 33711da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 33721da177e4SLinus Torvalds return -EPERM; 3373acfa4380SAl Viro if (!dir->i_op->link) 33741da177e4SLinus Torvalds return -EPERM; 33757e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 33761da177e4SLinus Torvalds return -EPERM; 33771da177e4SLinus Torvalds 33781da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 33791da177e4SLinus Torvalds if (error) 33801da177e4SLinus Torvalds return error; 33811da177e4SLinus Torvalds 33827e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 3383aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 3384aae8a97dSAneesh Kumar K.V if (inode->i_nlink == 0) 3385aae8a97dSAneesh Kumar K.V error = -ENOENT; 33868de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 33878de52778SAl Viro error = -EMLINK; 3388aae8a97dSAneesh Kumar K.V else 33891da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 33907e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 3391e31e14ecSStephen Smalley if (!error) 33927e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 33931da177e4SLinus Torvalds return error; 33941da177e4SLinus Torvalds } 33951da177e4SLinus Torvalds 33961da177e4SLinus Torvalds /* 33971da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 33981da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 33991da177e4SLinus Torvalds * newname. --KAB 34001da177e4SLinus Torvalds * 34011da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 34021da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 34031da177e4SLinus Torvalds * and other special files. --ADM 34041da177e4SLinus Torvalds */ 34052e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 34062e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 34071da177e4SLinus Torvalds { 34081da177e4SLinus Torvalds struct dentry *new_dentry; 3409dae6ad8fSAl Viro struct path old_path, new_path; 341011a7b371SAneesh Kumar K.V int how = 0; 34111da177e4SLinus Torvalds int error; 34121da177e4SLinus Torvalds 341311a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 3414c04030e1SUlrich Drepper return -EINVAL; 341511a7b371SAneesh Kumar K.V /* 341611a7b371SAneesh Kumar K.V * To use null names we require CAP_DAC_READ_SEARCH 341711a7b371SAneesh Kumar K.V * This ensures that not everyone will be able to create 341811a7b371SAneesh Kumar K.V * handlink using the passed filedescriptor. 341911a7b371SAneesh Kumar K.V */ 342011a7b371SAneesh Kumar K.V if (flags & AT_EMPTY_PATH) { 342111a7b371SAneesh Kumar K.V if (!capable(CAP_DAC_READ_SEARCH)) 342211a7b371SAneesh Kumar K.V return -ENOENT; 342311a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 342411a7b371SAneesh Kumar K.V } 3425c04030e1SUlrich Drepper 342611a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 342711a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 342811a7b371SAneesh Kumar K.V 342911a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 34301da177e4SLinus Torvalds if (error) 34312ad94ae6SAl Viro return error; 34322ad94ae6SAl Viro 3433dae6ad8fSAl Viro new_dentry = user_path_create(newdfd, newname, &new_path, 0); 34341da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 34356902d925SDave Hansen if (IS_ERR(new_dentry)) 3436dae6ad8fSAl Viro goto out; 3437dae6ad8fSAl Viro 3438dae6ad8fSAl Viro error = -EXDEV; 3439dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 3440dae6ad8fSAl Viro goto out_dput; 3441dae6ad8fSAl Viro error = mnt_want_write(new_path.mnt); 344275c3f29dSDave Hansen if (error) 344375c3f29dSDave Hansen goto out_dput; 3444dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 3445be6d3e56SKentaro Takeda if (error) 3446be6d3e56SKentaro Takeda goto out_drop_write; 3447dae6ad8fSAl Viro error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry); 3448be6d3e56SKentaro Takeda out_drop_write: 3449dae6ad8fSAl Viro mnt_drop_write(new_path.mnt); 345075c3f29dSDave Hansen out_dput: 3451921a1650SAl Viro done_path_create(&new_path, new_dentry); 34521da177e4SLinus Torvalds out: 34532d8f3038SAl Viro path_put(&old_path); 34541da177e4SLinus Torvalds 34551da177e4SLinus Torvalds return error; 34561da177e4SLinus Torvalds } 34571da177e4SLinus Torvalds 34583480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 34595590ff0dSUlrich Drepper { 3460c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 34615590ff0dSUlrich Drepper } 34625590ff0dSUlrich Drepper 34631da177e4SLinus Torvalds /* 34641da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 34651da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 34661da177e4SLinus Torvalds * Problems: 34671da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 34681da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 34691da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 3470a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 34711da177e4SLinus Torvalds * story. 34721da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 34731b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 34741da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 34751da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 3476a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 34771da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 34781da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 34791da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 3480a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 34811da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 34821da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 34831da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 3484e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 34851b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 34861da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 3487c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 34881da177e4SLinus Torvalds * locking]. 34891da177e4SLinus Torvalds */ 349075c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 34911da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 34921da177e4SLinus Torvalds { 34931da177e4SLinus Torvalds int error = 0; 34949055cba7SSage Weil struct inode *target = new_dentry->d_inode; 34958de52778SAl Viro unsigned max_links = new_dir->i_sb->s_max_links; 34961da177e4SLinus Torvalds 34971da177e4SLinus Torvalds /* 34981da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 34991da177e4SLinus Torvalds * we'll need to flip '..'. 35001da177e4SLinus Torvalds */ 35011da177e4SLinus Torvalds if (new_dir != old_dir) { 3502f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 35031da177e4SLinus Torvalds if (error) 35041da177e4SLinus Torvalds return error; 35051da177e4SLinus Torvalds } 35061da177e4SLinus Torvalds 35071da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 35081da177e4SLinus Torvalds if (error) 35091da177e4SLinus Torvalds return error; 35101da177e4SLinus Torvalds 35111d2ef590SAl Viro dget(new_dentry); 3512d83c49f3SAl Viro if (target) 35131b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 35149055cba7SSage Weil 35151da177e4SLinus Torvalds error = -EBUSY; 35169055cba7SSage Weil if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) 35179055cba7SSage Weil goto out; 35189055cba7SSage Weil 35198de52778SAl Viro error = -EMLINK; 35208de52778SAl Viro if (max_links && !target && new_dir != old_dir && 35218de52778SAl Viro new_dir->i_nlink >= max_links) 35228de52778SAl Viro goto out; 35238de52778SAl Viro 35243cebde24SSage Weil if (target) 35253cebde24SSage Weil shrink_dcache_parent(new_dentry); 35261da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 35279055cba7SSage Weil if (error) 35289055cba7SSage Weil goto out; 35299055cba7SSage Weil 35301da177e4SLinus Torvalds if (target) { 35311da177e4SLinus Torvalds target->i_flags |= S_DEAD; 3532d83c49f3SAl Viro dont_mount(new_dentry); 3533d83c49f3SAl Viro } 35349055cba7SSage Weil out: 35359055cba7SSage Weil if (target) 35361b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 35371d2ef590SAl Viro dput(new_dentry); 3538e31e14ecSStephen Smalley if (!error) 3539349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 35401da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 35411da177e4SLinus Torvalds return error; 35421da177e4SLinus Torvalds } 35431da177e4SLinus Torvalds 354475c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 35451da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 35461da177e4SLinus Torvalds { 354751892bbbSSage Weil struct inode *target = new_dentry->d_inode; 35481da177e4SLinus Torvalds int error; 35491da177e4SLinus Torvalds 35501da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 35511da177e4SLinus Torvalds if (error) 35521da177e4SLinus Torvalds return error; 35531da177e4SLinus Torvalds 35541da177e4SLinus Torvalds dget(new_dentry); 35551da177e4SLinus Torvalds if (target) 35561b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 355751892bbbSSage Weil 35581da177e4SLinus Torvalds error = -EBUSY; 355951892bbbSSage Weil if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 356051892bbbSSage Weil goto out; 356151892bbbSSage Weil 35621da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 356351892bbbSSage Weil if (error) 356451892bbbSSage Weil goto out; 356551892bbbSSage Weil 3566bec1052eSAl Viro if (target) 3567d83c49f3SAl Viro dont_mount(new_dentry); 3568349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 35691da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 357051892bbbSSage Weil out: 35711da177e4SLinus Torvalds if (target) 35721b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 35731da177e4SLinus Torvalds dput(new_dentry); 35741da177e4SLinus Torvalds return error; 35751da177e4SLinus Torvalds } 35761da177e4SLinus Torvalds 35771da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 35781da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 35791da177e4SLinus Torvalds { 35801da177e4SLinus Torvalds int error; 35811da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 358259b0df21SEric Paris const unsigned char *old_name; 35831da177e4SLinus Torvalds 35841da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 35851da177e4SLinus Torvalds return 0; 35861da177e4SLinus Torvalds 35871da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 35881da177e4SLinus Torvalds if (error) 35891da177e4SLinus Torvalds return error; 35901da177e4SLinus Torvalds 35911da177e4SLinus Torvalds if (!new_dentry->d_inode) 3592a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 35931da177e4SLinus Torvalds else 35941da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 35951da177e4SLinus Torvalds if (error) 35961da177e4SLinus Torvalds return error; 35971da177e4SLinus Torvalds 3598acfa4380SAl Viro if (!old_dir->i_op->rename) 35991da177e4SLinus Torvalds return -EPERM; 36001da177e4SLinus Torvalds 36010eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 36020eeca283SRobert Love 36031da177e4SLinus Torvalds if (is_dir) 36041da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 36051da177e4SLinus Torvalds else 36061da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 3607123df294SAl Viro if (!error) 3608123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 36095a190ae6SAl Viro new_dentry->d_inode, old_dentry); 36100eeca283SRobert Love fsnotify_oldname_free(old_name); 36110eeca283SRobert Love 36121da177e4SLinus Torvalds return error; 36131da177e4SLinus Torvalds } 36141da177e4SLinus Torvalds 36152e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 36162e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 36171da177e4SLinus Torvalds { 36181da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 36191da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 36201da177e4SLinus Torvalds struct dentry *trap; 36211da177e4SLinus Torvalds struct nameidata oldnd, newnd; 36222ad94ae6SAl Viro char *from; 36232ad94ae6SAl Viro char *to; 36242ad94ae6SAl Viro int error; 36251da177e4SLinus Torvalds 36262ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 36271da177e4SLinus Torvalds if (error) 36281da177e4SLinus Torvalds goto exit; 36291da177e4SLinus Torvalds 36302ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 36311da177e4SLinus Torvalds if (error) 36321da177e4SLinus Torvalds goto exit1; 36331da177e4SLinus Torvalds 36341da177e4SLinus Torvalds error = -EXDEV; 36354ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 36361da177e4SLinus Torvalds goto exit2; 36371da177e4SLinus Torvalds 36384ac91378SJan Blunck old_dir = oldnd.path.dentry; 36391da177e4SLinus Torvalds error = -EBUSY; 36401da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 36411da177e4SLinus Torvalds goto exit2; 36421da177e4SLinus Torvalds 36434ac91378SJan Blunck new_dir = newnd.path.dentry; 36441da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 36451da177e4SLinus Torvalds goto exit2; 36461da177e4SLinus Torvalds 36470612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 36480612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 36494e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 36500612d9fbSOGAWA Hirofumi 36511da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 36521da177e4SLinus Torvalds 365349705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 36541da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 36551da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 36561da177e4SLinus Torvalds goto exit3; 36571da177e4SLinus Torvalds /* source must exist */ 36581da177e4SLinus Torvalds error = -ENOENT; 36591da177e4SLinus Torvalds if (!old_dentry->d_inode) 36601da177e4SLinus Torvalds goto exit4; 36611da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 36621da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 36631da177e4SLinus Torvalds error = -ENOTDIR; 36641da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 36651da177e4SLinus Torvalds goto exit4; 36661da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 36671da177e4SLinus Torvalds goto exit4; 36681da177e4SLinus Torvalds } 36691da177e4SLinus Torvalds /* source should not be ancestor of target */ 36701da177e4SLinus Torvalds error = -EINVAL; 36711da177e4SLinus Torvalds if (old_dentry == trap) 36721da177e4SLinus Torvalds goto exit4; 367349705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 36741da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 36751da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 36761da177e4SLinus Torvalds goto exit4; 36771da177e4SLinus Torvalds /* target should not be an ancestor of source */ 36781da177e4SLinus Torvalds error = -ENOTEMPTY; 36791da177e4SLinus Torvalds if (new_dentry == trap) 36801da177e4SLinus Torvalds goto exit5; 36811da177e4SLinus Torvalds 36829079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 36839079b1ebSDave Hansen if (error) 36849079b1ebSDave Hansen goto exit5; 3685be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 3686be6d3e56SKentaro Takeda &newnd.path, new_dentry); 3687be6d3e56SKentaro Takeda if (error) 3688be6d3e56SKentaro Takeda goto exit6; 36891da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 36901da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 3691be6d3e56SKentaro Takeda exit6: 36929079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 36931da177e4SLinus Torvalds exit5: 36941da177e4SLinus Torvalds dput(new_dentry); 36951da177e4SLinus Torvalds exit4: 36961da177e4SLinus Torvalds dput(old_dentry); 36971da177e4SLinus Torvalds exit3: 36981da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 36991da177e4SLinus Torvalds exit2: 37001d957f9bSJan Blunck path_put(&newnd.path); 37012ad94ae6SAl Viro putname(to); 37021da177e4SLinus Torvalds exit1: 37031d957f9bSJan Blunck path_put(&oldnd.path); 37041da177e4SLinus Torvalds putname(from); 37052ad94ae6SAl Viro exit: 37061da177e4SLinus Torvalds return error; 37071da177e4SLinus Torvalds } 37081da177e4SLinus Torvalds 3709a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 37105590ff0dSUlrich Drepper { 37115590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 37125590ff0dSUlrich Drepper } 37135590ff0dSUlrich Drepper 37141da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 37151da177e4SLinus Torvalds { 37161da177e4SLinus Torvalds int len; 37171da177e4SLinus Torvalds 37181da177e4SLinus Torvalds len = PTR_ERR(link); 37191da177e4SLinus Torvalds if (IS_ERR(link)) 37201da177e4SLinus Torvalds goto out; 37211da177e4SLinus Torvalds 37221da177e4SLinus Torvalds len = strlen(link); 37231da177e4SLinus Torvalds if (len > (unsigned) buflen) 37241da177e4SLinus Torvalds len = buflen; 37251da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 37261da177e4SLinus Torvalds len = -EFAULT; 37271da177e4SLinus Torvalds out: 37281da177e4SLinus Torvalds return len; 37291da177e4SLinus Torvalds } 37301da177e4SLinus Torvalds 37311da177e4SLinus Torvalds /* 37321da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 37331da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 37341da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 37351da177e4SLinus Torvalds */ 37361da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 37371da177e4SLinus Torvalds { 37381da177e4SLinus Torvalds struct nameidata nd; 3739cc314eefSLinus Torvalds void *cookie; 3740694a1764SMarcin Slusarz int res; 3741cc314eefSLinus Torvalds 37421da177e4SLinus Torvalds nd.depth = 0; 3743cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 3744694a1764SMarcin Slusarz if (IS_ERR(cookie)) 3745694a1764SMarcin Slusarz return PTR_ERR(cookie); 3746694a1764SMarcin Slusarz 3747694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 37481da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 3749cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 3750694a1764SMarcin Slusarz return res; 37511da177e4SLinus Torvalds } 37521da177e4SLinus Torvalds 37531da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 37541da177e4SLinus Torvalds { 37551da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 37561da177e4SLinus Torvalds } 37571da177e4SLinus Torvalds 37581da177e4SLinus Torvalds /* get the link contents into pagecache */ 37591da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 37601da177e4SLinus Torvalds { 3761ebd09abbSDuane Griffin char *kaddr; 37621da177e4SLinus Torvalds struct page *page; 37631da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 3764090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 37651da177e4SLinus Torvalds if (IS_ERR(page)) 37666fe6900eSNick Piggin return (char*)page; 37671da177e4SLinus Torvalds *ppage = page; 3768ebd09abbSDuane Griffin kaddr = kmap(page); 3769ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 3770ebd09abbSDuane Griffin return kaddr; 37711da177e4SLinus Torvalds } 37721da177e4SLinus Torvalds 37731da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 37741da177e4SLinus Torvalds { 37751da177e4SLinus Torvalds struct page *page = NULL; 37761da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 37771da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 37781da177e4SLinus Torvalds if (page) { 37791da177e4SLinus Torvalds kunmap(page); 37801da177e4SLinus Torvalds page_cache_release(page); 37811da177e4SLinus Torvalds } 37821da177e4SLinus Torvalds return res; 37831da177e4SLinus Torvalds } 37841da177e4SLinus Torvalds 3785cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 37861da177e4SLinus Torvalds { 3787cc314eefSLinus Torvalds struct page *page = NULL; 37881da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 3789cc314eefSLinus Torvalds return page; 37901da177e4SLinus Torvalds } 37911da177e4SLinus Torvalds 3792cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 37931da177e4SLinus Torvalds { 3794cc314eefSLinus Torvalds struct page *page = cookie; 3795cc314eefSLinus Torvalds 3796cc314eefSLinus Torvalds if (page) { 37971da177e4SLinus Torvalds kunmap(page); 37981da177e4SLinus Torvalds page_cache_release(page); 37991da177e4SLinus Torvalds } 38001da177e4SLinus Torvalds } 38011da177e4SLinus Torvalds 380254566b2cSNick Piggin /* 380354566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 380454566b2cSNick Piggin */ 380554566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 38061da177e4SLinus Torvalds { 38071da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 38080adb25d2SKirill Korotaev struct page *page; 3809afddba49SNick Piggin void *fsdata; 3810beb497abSDmitriy Monakhov int err; 38111da177e4SLinus Torvalds char *kaddr; 381254566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 381354566b2cSNick Piggin if (nofs) 381454566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 38151da177e4SLinus Torvalds 38167e53cac4SNeilBrown retry: 3817afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 381854566b2cSNick Piggin flags, &page, &fsdata); 38191da177e4SLinus Torvalds if (err) 3820afddba49SNick Piggin goto fail; 3821afddba49SNick Piggin 3822e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 38231da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 3824e8e3c3d6SCong Wang kunmap_atomic(kaddr); 3825afddba49SNick Piggin 3826afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 3827afddba49SNick Piggin page, fsdata); 38281da177e4SLinus Torvalds if (err < 0) 38291da177e4SLinus Torvalds goto fail; 3830afddba49SNick Piggin if (err < len-1) 3831afddba49SNick Piggin goto retry; 3832afddba49SNick Piggin 38331da177e4SLinus Torvalds mark_inode_dirty(inode); 38341da177e4SLinus Torvalds return 0; 38351da177e4SLinus Torvalds fail: 38361da177e4SLinus Torvalds return err; 38371da177e4SLinus Torvalds } 38381da177e4SLinus Torvalds 38390adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 38400adb25d2SKirill Korotaev { 38410adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 384254566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 38430adb25d2SKirill Korotaev } 38440adb25d2SKirill Korotaev 384592e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 38461da177e4SLinus Torvalds .readlink = generic_readlink, 38471da177e4SLinus Torvalds .follow_link = page_follow_link_light, 38481da177e4SLinus Torvalds .put_link = page_put_link, 38491da177e4SLinus Torvalds }; 38501da177e4SLinus Torvalds 38512d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 3852cc53ce53SDavid Howells EXPORT_SYMBOL(follow_down_one); 38531da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 38541da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 38551da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 38561da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 38571da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 38581da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 38591da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 38601da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 38611da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 38620adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 38631da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 38641da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 3865d1811465SAl Viro EXPORT_SYMBOL(kern_path); 386616f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 3867f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 38681da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 38691da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 38701da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 38711da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 38721da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 38731da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 38741da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 38751da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 38761da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 38771da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 38781da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 38791da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 38801da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 38811da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 3882