11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namei.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Some corrections by tytso. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 121da177e4SLinus Torvalds * lookup logic. 131da177e4SLinus Torvalds */ 141da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 151da177e4SLinus Torvalds */ 161da177e4SLinus Torvalds 171da177e4SLinus Torvalds #include <linux/init.h> 18630d9c47SPaul Gortmaker #include <linux/export.h> 1944696908SDavid S. Miller #include <linux/kernel.h> 201da177e4SLinus Torvalds #include <linux/slab.h> 211da177e4SLinus Torvalds #include <linux/fs.h> 221da177e4SLinus Torvalds #include <linux/namei.h> 231da177e4SLinus Torvalds #include <linux/pagemap.h> 240eeca283SRobert Love #include <linux/fsnotify.h> 251da177e4SLinus Torvalds #include <linux/personality.h> 261da177e4SLinus Torvalds #include <linux/security.h> 276146f0d5SMimi Zohar #include <linux/ima.h> 281da177e4SLinus Torvalds #include <linux/syscalls.h> 291da177e4SLinus Torvalds #include <linux/mount.h> 301da177e4SLinus Torvalds #include <linux/audit.h> 3116f7e0feSRandy Dunlap #include <linux/capability.h> 32834f2a4aSTrond Myklebust #include <linux/file.h> 335590ff0dSUlrich Drepper #include <linux/fcntl.h> 3408ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 355ad4e53bSAl Viro #include <linux/fs_struct.h> 36e77819e5SLinus Torvalds #include <linux/posix_acl.h> 371da177e4SLinus Torvalds #include <asm/uaccess.h> 381da177e4SLinus Torvalds 39e81e3f4dSEric Paris #include "internal.h" 40c7105365SAl Viro #include "mount.h" 41e81e3f4dSEric Paris 421da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 431da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 441da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 451da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 461da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 471da177e4SLinus Torvalds * 481da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 491da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 501da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 511da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 521da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 531da177e4SLinus Torvalds * the special cases of the former code. 541da177e4SLinus Torvalds * 551da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 561da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 571da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 581da177e4SLinus Torvalds * 591da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 601da177e4SLinus Torvalds * resolution to correspond with current state of the code. 611da177e4SLinus Torvalds * 621da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 631da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 641da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 651da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 661da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 671da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 681da177e4SLinus Torvalds */ 691da177e4SLinus Torvalds 701da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 711da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 721da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 731da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 741da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 751da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7625985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 771da177e4SLinus Torvalds * 781da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 791da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 801da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 811da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 821da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 831da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 841da177e4SLinus Torvalds * and in the old Linux semantics. 851da177e4SLinus Torvalds */ 861da177e4SLinus Torvalds 871da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 881da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 891da177e4SLinus Torvalds * 901da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 911da177e4SLinus Torvalds */ 921da177e4SLinus Torvalds 931da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 941da177e4SLinus Torvalds * inside the path - always follow. 951da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 961da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 971da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 981da177e4SLinus Torvalds * otherwise - don't follow. 991da177e4SLinus Torvalds * (applied in that order). 1001da177e4SLinus Torvalds * 1011da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1021da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1031da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1041da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1051da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1061da177e4SLinus Torvalds */ 1071da177e4SLinus Torvalds /* 1081da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 109a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1101da177e4SLinus Torvalds * any extra contention... 1111da177e4SLinus Torvalds */ 1121da177e4SLinus Torvalds 1131da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1141da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1151da177e4SLinus Torvalds * kernel data space before using them.. 1161da177e4SLinus Torvalds * 1171da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1181da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1191da177e4SLinus Torvalds */ 1201fa1e7f6SAndy Whitcroft static char *getname_flags(const char __user *filename, int flags, int *empty) 1211da177e4SLinus Torvalds { 1223f9f0aa6SLinus Torvalds char *result = __getname(), *err; 1233f9f0aa6SLinus Torvalds int len; 1241da177e4SLinus Torvalds 1253f9f0aa6SLinus Torvalds if (unlikely(!result)) 1264043cde8SEric Paris return ERR_PTR(-ENOMEM); 1271da177e4SLinus Torvalds 1283f9f0aa6SLinus Torvalds len = strncpy_from_user(result, filename, PATH_MAX); 1293f9f0aa6SLinus Torvalds err = ERR_PTR(len); 1303f9f0aa6SLinus Torvalds if (unlikely(len < 0)) 1313f9f0aa6SLinus Torvalds goto error; 1323f9f0aa6SLinus Torvalds 1333f9f0aa6SLinus Torvalds /* The empty path is special. */ 1343f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1353f9f0aa6SLinus Torvalds if (empty) 1361fa1e7f6SAndy Whitcroft *empty = 1; 1373f9f0aa6SLinus Torvalds err = ERR_PTR(-ENOENT); 1383f9f0aa6SLinus Torvalds if (!(flags & LOOKUP_EMPTY)) 1393f9f0aa6SLinus Torvalds goto error; 1401da177e4SLinus Torvalds } 1413f9f0aa6SLinus Torvalds 1423f9f0aa6SLinus Torvalds err = ERR_PTR(-ENAMETOOLONG); 1433f9f0aa6SLinus Torvalds if (likely(len < PATH_MAX)) { 1441da177e4SLinus Torvalds audit_getname(result); 1451da177e4SLinus Torvalds return result; 1461da177e4SLinus Torvalds } 1471da177e4SLinus Torvalds 1483f9f0aa6SLinus Torvalds error: 1493f9f0aa6SLinus Torvalds __putname(result); 1503f9f0aa6SLinus Torvalds return err; 1513f9f0aa6SLinus Torvalds } 1523f9f0aa6SLinus Torvalds 153f52e0c11SAl Viro char *getname(const char __user * filename) 154f52e0c11SAl Viro { 155f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 156f52e0c11SAl Viro } 157f52e0c11SAl Viro 1581da177e4SLinus Torvalds #ifdef CONFIG_AUDITSYSCALL 1591da177e4SLinus Torvalds void putname(const char *name) 1601da177e4SLinus Torvalds { 1615ac3a9c2SAl Viro if (unlikely(!audit_dummy_context())) 1621da177e4SLinus Torvalds audit_putname(name); 1631da177e4SLinus Torvalds else 1641da177e4SLinus Torvalds __putname(name); 1651da177e4SLinus Torvalds } 1661da177e4SLinus Torvalds EXPORT_SYMBOL(putname); 1671da177e4SLinus Torvalds #endif 1681da177e4SLinus Torvalds 169e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 170e77819e5SLinus Torvalds { 17184635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 172e77819e5SLinus Torvalds struct posix_acl *acl; 173e77819e5SLinus Torvalds 174e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 1753567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 1763567866bSAl Viro if (!acl) 177e77819e5SLinus Torvalds return -EAGAIN; 1783567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 1793567866bSAl Viro if (acl == ACL_NOT_CACHED) 180e77819e5SLinus Torvalds return -ECHILD; 181206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 182e77819e5SLinus Torvalds } 183e77819e5SLinus Torvalds 184e77819e5SLinus Torvalds acl = get_cached_acl(inode, ACL_TYPE_ACCESS); 185e77819e5SLinus Torvalds 186e77819e5SLinus Torvalds /* 1874e34e719SChristoph Hellwig * A filesystem can force a ACL callback by just never filling the 1884e34e719SChristoph Hellwig * ACL cache. But normally you'd fill the cache either at inode 1894e34e719SChristoph Hellwig * instantiation time, or on the first ->get_acl call. 190e77819e5SLinus Torvalds * 1914e34e719SChristoph Hellwig * If the filesystem doesn't have a get_acl() function at all, we'll 1924e34e719SChristoph Hellwig * just create the negative cache entry. 193e77819e5SLinus Torvalds */ 194e77819e5SLinus Torvalds if (acl == ACL_NOT_CACHED) { 1954e34e719SChristoph Hellwig if (inode->i_op->get_acl) { 1964e34e719SChristoph Hellwig acl = inode->i_op->get_acl(inode, ACL_TYPE_ACCESS); 1974e34e719SChristoph Hellwig if (IS_ERR(acl)) 1984e34e719SChristoph Hellwig return PTR_ERR(acl); 1994e34e719SChristoph Hellwig } else { 200e77819e5SLinus Torvalds set_cached_acl(inode, ACL_TYPE_ACCESS, NULL); 201e77819e5SLinus Torvalds return -EAGAIN; 202e77819e5SLinus Torvalds } 2034e34e719SChristoph Hellwig } 204e77819e5SLinus Torvalds 205e77819e5SLinus Torvalds if (acl) { 206e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 207e77819e5SLinus Torvalds posix_acl_release(acl); 208e77819e5SLinus Torvalds return error; 209e77819e5SLinus Torvalds } 21084635d68SLinus Torvalds #endif 211e77819e5SLinus Torvalds 212e77819e5SLinus Torvalds return -EAGAIN; 213e77819e5SLinus Torvalds } 214e77819e5SLinus Torvalds 2155909ccaaSLinus Torvalds /* 216948409c7SAndreas Gruenbacher * This does the basic permission checking 2175909ccaaSLinus Torvalds */ 2187e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2195909ccaaSLinus Torvalds { 22026cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2215909ccaaSLinus Torvalds 2228e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2235909ccaaSLinus Torvalds mode >>= 6; 2245909ccaaSLinus Torvalds else { 225e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2267e40145eSAl Viro int error = check_acl(inode, mask); 2275909ccaaSLinus Torvalds if (error != -EAGAIN) 2285909ccaaSLinus Torvalds return error; 2295909ccaaSLinus Torvalds } 2305909ccaaSLinus Torvalds 2315909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 2325909ccaaSLinus Torvalds mode >>= 3; 2335909ccaaSLinus Torvalds } 2345909ccaaSLinus Torvalds 2355909ccaaSLinus Torvalds /* 2365909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 2375909ccaaSLinus Torvalds */ 2389c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 2395909ccaaSLinus Torvalds return 0; 2405909ccaaSLinus Torvalds return -EACCES; 2415909ccaaSLinus Torvalds } 2421da177e4SLinus Torvalds 2431da177e4SLinus Torvalds /** 2441da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 2451da177e4SLinus Torvalds * @inode: inode to check access rights for 2468fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 2471da177e4SLinus Torvalds * 2481da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 2491da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 2501da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 251b74c79e9SNick Piggin * are used for other things. 252b74c79e9SNick Piggin * 253b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 254b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 255b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 2561da177e4SLinus Torvalds */ 2572830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 2581da177e4SLinus Torvalds { 2595909ccaaSLinus Torvalds int ret; 2601da177e4SLinus Torvalds 2611da177e4SLinus Torvalds /* 262948409c7SAndreas Gruenbacher * Do the basic permission checks. 2631da177e4SLinus Torvalds */ 2647e40145eSAl Viro ret = acl_permission_check(inode, mask); 2655909ccaaSLinus Torvalds if (ret != -EACCES) 2665909ccaaSLinus Torvalds return ret; 2671da177e4SLinus Torvalds 268d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 269d594e7ecSAl Viro /* DACs are overridable for directories */ 2701a48e2acSEric W. Biederman if (inode_capable(inode, CAP_DAC_OVERRIDE)) 271d594e7ecSAl Viro return 0; 272d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 2731a48e2acSEric W. Biederman if (inode_capable(inode, CAP_DAC_READ_SEARCH)) 274d594e7ecSAl Viro return 0; 275d594e7ecSAl Viro return -EACCES; 276d594e7ecSAl Viro } 2771da177e4SLinus Torvalds /* 2781da177e4SLinus Torvalds * Read/write DACs are always overridable. 279d594e7ecSAl Viro * Executable DACs are overridable when there is 280d594e7ecSAl Viro * at least one exec bit set. 2811da177e4SLinus Torvalds */ 282d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 2831a48e2acSEric W. Biederman if (inode_capable(inode, CAP_DAC_OVERRIDE)) 2841da177e4SLinus Torvalds return 0; 2851da177e4SLinus Torvalds 2861da177e4SLinus Torvalds /* 2871da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 2881da177e4SLinus Torvalds */ 2897ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 290d594e7ecSAl Viro if (mask == MAY_READ) 2911a48e2acSEric W. Biederman if (inode_capable(inode, CAP_DAC_READ_SEARCH)) 2921da177e4SLinus Torvalds return 0; 2931da177e4SLinus Torvalds 2941da177e4SLinus Torvalds return -EACCES; 2951da177e4SLinus Torvalds } 2961da177e4SLinus Torvalds 2973ddcd056SLinus Torvalds /* 2983ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 2993ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3003ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3013ddcd056SLinus Torvalds * permission function, use the fast case". 3023ddcd056SLinus Torvalds */ 3033ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3043ddcd056SLinus Torvalds { 3053ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3063ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3073ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3083ddcd056SLinus Torvalds 3093ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3103ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3113ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3123ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3133ddcd056SLinus Torvalds } 3143ddcd056SLinus Torvalds return generic_permission(inode, mask); 3153ddcd056SLinus Torvalds } 3163ddcd056SLinus Torvalds 317cb23beb5SChristoph Hellwig /** 3180bdaea90SDavid Howells * __inode_permission - Check for access rights to a given inode 3190bdaea90SDavid Howells * @inode: Inode to check permission on 3200bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 321cb23beb5SChristoph Hellwig * 3220bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. 323948409c7SAndreas Gruenbacher * 324948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 3250bdaea90SDavid Howells * 3260bdaea90SDavid Howells * This does not check for a read-only file system. You probably want 3270bdaea90SDavid Howells * inode_permission(). 328cb23beb5SChristoph Hellwig */ 3290bdaea90SDavid Howells int __inode_permission(struct inode *inode, int mask) 3301da177e4SLinus Torvalds { 331e6305c43SAl Viro int retval; 3321da177e4SLinus Torvalds 3333ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 3341da177e4SLinus Torvalds /* 3351da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 3361da177e4SLinus Torvalds */ 3371da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 3381da177e4SLinus Torvalds return -EACCES; 3391da177e4SLinus Torvalds } 3401da177e4SLinus Torvalds 3413ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 3421da177e4SLinus Torvalds if (retval) 3431da177e4SLinus Torvalds return retval; 3441da177e4SLinus Torvalds 34508ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 34608ce5f16SSerge E. Hallyn if (retval) 34708ce5f16SSerge E. Hallyn return retval; 34808ce5f16SSerge E. Hallyn 349d09ca739SEric Paris return security_inode_permission(inode, mask); 3501da177e4SLinus Torvalds } 3511da177e4SLinus Torvalds 352f4d6ff89SAl Viro /** 3530bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 3540bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 3550bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 3560bdaea90SDavid Howells * 3570bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 3580bdaea90SDavid Howells */ 3590bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 3600bdaea90SDavid Howells { 3610bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 3620bdaea90SDavid Howells umode_t mode = inode->i_mode; 3630bdaea90SDavid Howells 3640bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 3650bdaea90SDavid Howells if ((sb->s_flags & MS_RDONLY) && 3660bdaea90SDavid Howells (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 3670bdaea90SDavid Howells return -EROFS; 3680bdaea90SDavid Howells } 3690bdaea90SDavid Howells return 0; 3700bdaea90SDavid Howells } 3710bdaea90SDavid Howells 3720bdaea90SDavid Howells /** 3730bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 3740bdaea90SDavid Howells * @inode: Inode to check permission on 3750bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 3760bdaea90SDavid Howells * 3770bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 3780bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 3790bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 3800bdaea90SDavid Howells * 3810bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 3820bdaea90SDavid Howells */ 3830bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 3840bdaea90SDavid Howells { 3850bdaea90SDavid Howells int retval; 3860bdaea90SDavid Howells 3870bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 3880bdaea90SDavid Howells if (retval) 3890bdaea90SDavid Howells return retval; 3900bdaea90SDavid Howells return __inode_permission(inode, mask); 3910bdaea90SDavid Howells } 3920bdaea90SDavid Howells 3930bdaea90SDavid Howells /** 3945dd784d0SJan Blunck * path_get - get a reference to a path 3955dd784d0SJan Blunck * @path: path to get the reference to 3965dd784d0SJan Blunck * 3975dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 3985dd784d0SJan Blunck */ 3995dd784d0SJan Blunck void path_get(struct path *path) 4005dd784d0SJan Blunck { 4015dd784d0SJan Blunck mntget(path->mnt); 4025dd784d0SJan Blunck dget(path->dentry); 4035dd784d0SJan Blunck } 4045dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4055dd784d0SJan Blunck 4065dd784d0SJan Blunck /** 4071d957f9bSJan Blunck * path_put - put a reference to a path 4081d957f9bSJan Blunck * @path: path to put the reference to 4091d957f9bSJan Blunck * 4101d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4111d957f9bSJan Blunck */ 4121d957f9bSJan Blunck void path_put(struct path *path) 4131da177e4SLinus Torvalds { 4141d957f9bSJan Blunck dput(path->dentry); 4151d957f9bSJan Blunck mntput(path->mnt); 4161da177e4SLinus Torvalds } 4171d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4181da177e4SLinus Torvalds 41919660af7SAl Viro /* 42031e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 42119660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 42219660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 42319660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 42419660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 42519660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 42619660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 42719660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 42831e6b01fSNick Piggin */ 42931e6b01fSNick Piggin 43032a7991bSAl Viro static inline void lock_rcu_walk(void) 43132a7991bSAl Viro { 43232a7991bSAl Viro br_read_lock(&vfsmount_lock); 43332a7991bSAl Viro rcu_read_lock(); 43432a7991bSAl Viro } 43532a7991bSAl Viro 43632a7991bSAl Viro static inline void unlock_rcu_walk(void) 43732a7991bSAl Viro { 43832a7991bSAl Viro rcu_read_unlock(); 43932a7991bSAl Viro br_read_unlock(&vfsmount_lock); 44032a7991bSAl Viro } 44132a7991bSAl Viro 44231e6b01fSNick Piggin /** 44319660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 44419660af7SAl Viro * @nd: nameidata pathwalk data 44519660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 44639191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 44731e6b01fSNick Piggin * 44819660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 44919660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 45019660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 45131e6b01fSNick Piggin */ 45219660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 45331e6b01fSNick Piggin { 45431e6b01fSNick Piggin struct fs_struct *fs = current->fs; 45531e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 4565b6ca027SAl Viro int want_root = 0; 45731e6b01fSNick Piggin 45831e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 4595b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 4605b6ca027SAl Viro want_root = 1; 46131e6b01fSNick Piggin spin_lock(&fs->lock); 46231e6b01fSNick Piggin if (nd->root.mnt != fs->root.mnt || 46331e6b01fSNick Piggin nd->root.dentry != fs->root.dentry) 46431e6b01fSNick Piggin goto err_root; 46531e6b01fSNick Piggin } 46631e6b01fSNick Piggin spin_lock(&parent->d_lock); 46719660af7SAl Viro if (!dentry) { 46819660af7SAl Viro if (!__d_rcu_to_refcount(parent, nd->seq)) 46919660af7SAl Viro goto err_parent; 47019660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 47119660af7SAl Viro } else { 47294c0d4ecSAl Viro if (dentry->d_parent != parent) 47394c0d4ecSAl Viro goto err_parent; 47431e6b01fSNick Piggin spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); 47531e6b01fSNick Piggin if (!__d_rcu_to_refcount(dentry, nd->seq)) 47619660af7SAl Viro goto err_child; 47731e6b01fSNick Piggin /* 47819660af7SAl Viro * If the sequence check on the child dentry passed, then 47919660af7SAl Viro * the child has not been removed from its parent. This 48019660af7SAl Viro * means the parent dentry must be valid and able to take 48119660af7SAl Viro * a reference at this point. 48231e6b01fSNick Piggin */ 48331e6b01fSNick Piggin BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent); 48431e6b01fSNick Piggin BUG_ON(!parent->d_count); 48531e6b01fSNick Piggin parent->d_count++; 48631e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 48719660af7SAl Viro } 48831e6b01fSNick Piggin spin_unlock(&parent->d_lock); 4895b6ca027SAl Viro if (want_root) { 49031e6b01fSNick Piggin path_get(&nd->root); 49131e6b01fSNick Piggin spin_unlock(&fs->lock); 49231e6b01fSNick Piggin } 49331e6b01fSNick Piggin mntget(nd->path.mnt); 49431e6b01fSNick Piggin 49532a7991bSAl Viro unlock_rcu_walk(); 49631e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 49731e6b01fSNick Piggin return 0; 49819660af7SAl Viro 49919660af7SAl Viro err_child: 50031e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 50119660af7SAl Viro err_parent: 50231e6b01fSNick Piggin spin_unlock(&parent->d_lock); 50331e6b01fSNick Piggin err_root: 5045b6ca027SAl Viro if (want_root) 50531e6b01fSNick Piggin spin_unlock(&fs->lock); 50631e6b01fSNick Piggin return -ECHILD; 50731e6b01fSNick Piggin } 50831e6b01fSNick Piggin 5094ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 51034286d66SNick Piggin { 5114ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 51234286d66SNick Piggin } 51334286d66SNick Piggin 5149f1fafeeSAl Viro /** 5159f1fafeeSAl Viro * complete_walk - successful completion of path walk 5169f1fafeeSAl Viro * @nd: pointer nameidata 51739159de2SJeff Layton * 5189f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 5199f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 5209f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 5219f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 5229f1fafeeSAl Viro * need to drop nd->path. 52339159de2SJeff Layton */ 5249f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 52539159de2SJeff Layton { 52616c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 52739159de2SJeff Layton int status; 52839159de2SJeff Layton 5299f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 5309f1fafeeSAl Viro nd->flags &= ~LOOKUP_RCU; 5319f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 5329f1fafeeSAl Viro nd->root.mnt = NULL; 5339f1fafeeSAl Viro spin_lock(&dentry->d_lock); 5349f1fafeeSAl Viro if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) { 5359f1fafeeSAl Viro spin_unlock(&dentry->d_lock); 53632a7991bSAl Viro unlock_rcu_walk(); 5379f1fafeeSAl Viro return -ECHILD; 5389f1fafeeSAl Viro } 5399f1fafeeSAl Viro BUG_ON(nd->inode != dentry->d_inode); 5409f1fafeeSAl Viro spin_unlock(&dentry->d_lock); 5419f1fafeeSAl Viro mntget(nd->path.mnt); 54232a7991bSAl Viro unlock_rcu_walk(); 5439f1fafeeSAl Viro } 5449f1fafeeSAl Viro 54516c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 54639159de2SJeff Layton return 0; 54739159de2SJeff Layton 54816c2cd71SAl Viro if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE))) 54916c2cd71SAl Viro return 0; 55016c2cd71SAl Viro 55116c2cd71SAl Viro if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))) 55216c2cd71SAl Viro return 0; 55316c2cd71SAl Viro 55416c2cd71SAl Viro /* Note: we do not d_invalidate() */ 5554ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 55639159de2SJeff Layton if (status > 0) 55739159de2SJeff Layton return 0; 55839159de2SJeff Layton 55916c2cd71SAl Viro if (!status) 56039159de2SJeff Layton status = -ESTALE; 56116c2cd71SAl Viro 5629f1fafeeSAl Viro path_put(&nd->path); 56339159de2SJeff Layton return status; 56439159de2SJeff Layton } 56539159de2SJeff Layton 5662a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 5672a737871SAl Viro { 568f7ad3c6bSMiklos Szeredi if (!nd->root.mnt) 569f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 5702a737871SAl Viro } 5712a737871SAl Viro 5726de88d72SAl Viro static int link_path_walk(const char *, struct nameidata *); 5736de88d72SAl Viro 57431e6b01fSNick Piggin static __always_inline void set_root_rcu(struct nameidata *nd) 57531e6b01fSNick Piggin { 57631e6b01fSNick Piggin if (!nd->root.mnt) { 57731e6b01fSNick Piggin struct fs_struct *fs = current->fs; 578c28cc364SNick Piggin unsigned seq; 579c28cc364SNick Piggin 580c28cc364SNick Piggin do { 581c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 58231e6b01fSNick Piggin nd->root = fs->root; 583c1530019STim Chen nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 584c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 58531e6b01fSNick Piggin } 58631e6b01fSNick Piggin } 58731e6b01fSNick Piggin 588f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 5891da177e4SLinus Torvalds { 59031e6b01fSNick Piggin int ret; 59131e6b01fSNick Piggin 5921da177e4SLinus Torvalds if (IS_ERR(link)) 5931da177e4SLinus Torvalds goto fail; 5941da177e4SLinus Torvalds 5951da177e4SLinus Torvalds if (*link == '/') { 5962a737871SAl Viro set_root(nd); 5971d957f9bSJan Blunck path_put(&nd->path); 5982a737871SAl Viro nd->path = nd->root; 5992a737871SAl Viro path_get(&nd->root); 60016c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 6011da177e4SLinus Torvalds } 60231e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 603b4091d5fSChristoph Hellwig 60431e6b01fSNick Piggin ret = link_path_walk(link, nd); 60531e6b01fSNick Piggin return ret; 6061da177e4SLinus Torvalds fail: 6071d957f9bSJan Blunck path_put(&nd->path); 6081da177e4SLinus Torvalds return PTR_ERR(link); 6091da177e4SLinus Torvalds } 6101da177e4SLinus Torvalds 6111d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 612051d3812SIan Kent { 613051d3812SIan Kent dput(path->dentry); 6144ac91378SJan Blunck if (path->mnt != nd->path.mnt) 615051d3812SIan Kent mntput(path->mnt); 616051d3812SIan Kent } 617051d3812SIan Kent 6187b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 6197b9337aaSNick Piggin struct nameidata *nd) 620051d3812SIan Kent { 62131e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 6224ac91378SJan Blunck dput(nd->path.dentry); 62331e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 6244ac91378SJan Blunck mntput(nd->path.mnt); 6259a229683SHuang Shijie } 62631e6b01fSNick Piggin nd->path.mnt = path->mnt; 6274ac91378SJan Blunck nd->path.dentry = path->dentry; 628051d3812SIan Kent } 629051d3812SIan Kent 630b5fb63c1SChristoph Hellwig /* 631b5fb63c1SChristoph Hellwig * Helper to directly jump to a known parsed path from ->follow_link, 632b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 633b5fb63c1SChristoph Hellwig */ 634b5fb63c1SChristoph Hellwig void nd_jump_link(struct nameidata *nd, struct path *path) 635b5fb63c1SChristoph Hellwig { 636b5fb63c1SChristoph Hellwig path_put(&nd->path); 637b5fb63c1SChristoph Hellwig 638b5fb63c1SChristoph Hellwig nd->path = *path; 639b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 640b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 641b5fb63c1SChristoph Hellwig 642b5fb63c1SChristoph Hellwig BUG_ON(nd->inode->i_op->follow_link); 643b5fb63c1SChristoph Hellwig } 644b5fb63c1SChristoph Hellwig 645574197e0SAl Viro static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) 646574197e0SAl Viro { 647574197e0SAl Viro struct inode *inode = link->dentry->d_inode; 6486d7b5aaeSAl Viro if (inode->i_op->put_link) 649574197e0SAl Viro inode->i_op->put_link(link->dentry, nd, cookie); 650574197e0SAl Viro path_put(link); 651574197e0SAl Viro } 652574197e0SAl Viro 653800179c9SKees Cook int sysctl_protected_symlinks __read_mostly = 1; 654800179c9SKees Cook int sysctl_protected_hardlinks __read_mostly = 1; 655800179c9SKees Cook 656800179c9SKees Cook /** 657800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 658800179c9SKees Cook * @link: The path of the symlink 659800179c9SKees Cook * 660800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 661800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 662800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 663800179c9SKees Cook * processes from failing races against path names that may change out 664800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 665800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 666800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 667800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 668800179c9SKees Cook * 669800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 670800179c9SKees Cook */ 671800179c9SKees Cook static inline int may_follow_link(struct path *link, struct nameidata *nd) 672800179c9SKees Cook { 673800179c9SKees Cook const struct inode *inode; 674800179c9SKees Cook const struct inode *parent; 675800179c9SKees Cook 676800179c9SKees Cook if (!sysctl_protected_symlinks) 677800179c9SKees Cook return 0; 678800179c9SKees Cook 679800179c9SKees Cook /* Allowed if owner and follower match. */ 680800179c9SKees Cook inode = link->dentry->d_inode; 681800179c9SKees Cook if (current_cred()->fsuid == inode->i_uid) 682800179c9SKees Cook return 0; 683800179c9SKees Cook 684800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 685800179c9SKees Cook parent = nd->path.dentry->d_inode; 686800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 687800179c9SKees Cook return 0; 688800179c9SKees Cook 689800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 690800179c9SKees Cook if (parent->i_uid == inode->i_uid) 691800179c9SKees Cook return 0; 692800179c9SKees Cook 693800179c9SKees Cook path_put_conditional(link, nd); 694800179c9SKees Cook path_put(&nd->path); 695a51d9eaaSKees Cook audit_log_link_denied("follow_link", link); 696800179c9SKees Cook return -EACCES; 697800179c9SKees Cook } 698800179c9SKees Cook 699800179c9SKees Cook /** 700800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 701800179c9SKees Cook * @inode: the source inode to hardlink from 702800179c9SKees Cook * 703800179c9SKees Cook * Return false if at least one of the following conditions: 704800179c9SKees Cook * - inode is not a regular file 705800179c9SKees Cook * - inode is setuid 706800179c9SKees Cook * - inode is setgid and group-exec 707800179c9SKees Cook * - access failure for read and write 708800179c9SKees Cook * 709800179c9SKees Cook * Otherwise returns true. 710800179c9SKees Cook */ 711800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 712800179c9SKees Cook { 713800179c9SKees Cook umode_t mode = inode->i_mode; 714800179c9SKees Cook 715800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 716800179c9SKees Cook if (!S_ISREG(mode)) 717800179c9SKees Cook return false; 718800179c9SKees Cook 719800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 720800179c9SKees Cook if (mode & S_ISUID) 721800179c9SKees Cook return false; 722800179c9SKees Cook 723800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 724800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 725800179c9SKees Cook return false; 726800179c9SKees Cook 727800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 728800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 729800179c9SKees Cook return false; 730800179c9SKees Cook 731800179c9SKees Cook return true; 732800179c9SKees Cook } 733800179c9SKees Cook 734800179c9SKees Cook /** 735800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 736800179c9SKees Cook * @link: the source to hardlink from 737800179c9SKees Cook * 738800179c9SKees Cook * Block hardlink when all of: 739800179c9SKees Cook * - sysctl_protected_hardlinks enabled 740800179c9SKees Cook * - fsuid does not match inode 741800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 742800179c9SKees Cook * - not CAP_FOWNER 743800179c9SKees Cook * 744800179c9SKees Cook * Returns 0 if successful, -ve on error. 745800179c9SKees Cook */ 746800179c9SKees Cook static int may_linkat(struct path *link) 747800179c9SKees Cook { 748800179c9SKees Cook const struct cred *cred; 749800179c9SKees Cook struct inode *inode; 750800179c9SKees Cook 751800179c9SKees Cook if (!sysctl_protected_hardlinks) 752800179c9SKees Cook return 0; 753800179c9SKees Cook 754800179c9SKees Cook cred = current_cred(); 755800179c9SKees Cook inode = link->dentry->d_inode; 756800179c9SKees Cook 757800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 758800179c9SKees Cook * otherwise, it must be a safe source. 759800179c9SKees Cook */ 760800179c9SKees Cook if (cred->fsuid == inode->i_uid || safe_hardlink_source(inode) || 761800179c9SKees Cook capable(CAP_FOWNER)) 762800179c9SKees Cook return 0; 763800179c9SKees Cook 764a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 765800179c9SKees Cook return -EPERM; 766800179c9SKees Cook } 767800179c9SKees Cook 768def4af30SAl Viro static __always_inline int 769574197e0SAl Viro follow_link(struct path *link, struct nameidata *nd, void **p) 7701da177e4SLinus Torvalds { 7717b9337aaSNick Piggin struct dentry *dentry = link->dentry; 7726d7b5aaeSAl Viro int error; 7736d7b5aaeSAl Viro char *s; 7741da177e4SLinus Torvalds 775844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 776844a3917SAl Viro 7770e794589SAl Viro if (link->mnt == nd->path.mnt) 7780e794589SAl Viro mntget(link->mnt); 7790e794589SAl Viro 7806d7b5aaeSAl Viro error = -ELOOP; 7816d7b5aaeSAl Viro if (unlikely(current->total_link_count >= 40)) 7826d7b5aaeSAl Viro goto out_put_nd_path; 7836d7b5aaeSAl Viro 784574197e0SAl Viro cond_resched(); 785574197e0SAl Viro current->total_link_count++; 786574197e0SAl Viro 78768ac1234SAl Viro touch_atime(link); 7881da177e4SLinus Torvalds nd_set_link(nd, NULL); 789cd4e91d3SAl Viro 79036f3b4f6SAl Viro error = security_inode_follow_link(link->dentry, nd); 7916d7b5aaeSAl Viro if (error) 7926d7b5aaeSAl Viro goto out_put_nd_path; 79336f3b4f6SAl Viro 79486acdca1SAl Viro nd->last_type = LAST_BIND; 795def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 796def4af30SAl Viro error = PTR_ERR(*p); 7976d7b5aaeSAl Viro if (IS_ERR(*p)) 798408ef013SChristoph Hellwig goto out_put_nd_path; 7996d7b5aaeSAl Viro 800cc314eefSLinus Torvalds error = 0; 8016d7b5aaeSAl Viro s = nd_get_link(nd); 8026d7b5aaeSAl Viro if (s) { 8031da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 8046d7b5aaeSAl Viro if (unlikely(error)) 8056d7b5aaeSAl Viro put_link(nd, link, *p); 806b5fb63c1SChristoph Hellwig } 8076d7b5aaeSAl Viro 8086d7b5aaeSAl Viro return error; 8096d7b5aaeSAl Viro 8106d7b5aaeSAl Viro out_put_nd_path: 8116d7b5aaeSAl Viro path_put(&nd->path); 8126d7b5aaeSAl Viro path_put(link); 8131da177e4SLinus Torvalds return error; 8141da177e4SLinus Torvalds } 8151da177e4SLinus Torvalds 81631e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 81731e6b01fSNick Piggin { 8180714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 8190714a533SAl Viro struct mount *parent; 82031e6b01fSNick Piggin struct dentry *mountpoint; 82131e6b01fSNick Piggin 8220714a533SAl Viro parent = mnt->mnt_parent; 8230714a533SAl Viro if (&parent->mnt == path->mnt) 82431e6b01fSNick Piggin return 0; 825a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 82631e6b01fSNick Piggin path->dentry = mountpoint; 8270714a533SAl Viro path->mnt = &parent->mnt; 82831e6b01fSNick Piggin return 1; 82931e6b01fSNick Piggin } 83031e6b01fSNick Piggin 831f015f126SDavid Howells /* 832f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 833f015f126SDavid Howells * 834f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 835f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 836f015f126SDavid Howells * Up is towards /. 837f015f126SDavid Howells * 838f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 839f015f126SDavid Howells * root. 840f015f126SDavid Howells */ 841bab77ebfSAl Viro int follow_up(struct path *path) 8421da177e4SLinus Torvalds { 8430714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 8440714a533SAl Viro struct mount *parent; 8451da177e4SLinus Torvalds struct dentry *mountpoint; 84699b7db7bSNick Piggin 847962830dfSAndi Kleen br_read_lock(&vfsmount_lock); 8480714a533SAl Viro parent = mnt->mnt_parent; 8493c0a6163SAl Viro if (parent == mnt) { 850962830dfSAndi Kleen br_read_unlock(&vfsmount_lock); 8511da177e4SLinus Torvalds return 0; 8521da177e4SLinus Torvalds } 8530714a533SAl Viro mntget(&parent->mnt); 854a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 855962830dfSAndi Kleen br_read_unlock(&vfsmount_lock); 856bab77ebfSAl Viro dput(path->dentry); 857bab77ebfSAl Viro path->dentry = mountpoint; 858bab77ebfSAl Viro mntput(path->mnt); 8590714a533SAl Viro path->mnt = &parent->mnt; 8601da177e4SLinus Torvalds return 1; 8611da177e4SLinus Torvalds } 8621da177e4SLinus Torvalds 863b5c84bf6SNick Piggin /* 8649875cf80SDavid Howells * Perform an automount 8659875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 8669875cf80SDavid Howells * were called with. 8671da177e4SLinus Torvalds */ 8689875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 8699875cf80SDavid Howells bool *need_mntput) 87031e6b01fSNick Piggin { 8719875cf80SDavid Howells struct vfsmount *mnt; 872ea5b778aSDavid Howells int err; 8739875cf80SDavid Howells 8749875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 8759875cf80SDavid Howells return -EREMOTE; 8769875cf80SDavid Howells 8770ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 8780ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 8790ec26fd0SMiklos Szeredi * the name. 8800ec26fd0SMiklos Szeredi * 8810ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 8825a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 8830ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 8840ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 8850ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 8860ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 8875a30d8a2SDavid Howells */ 8885a30d8a2SDavid Howells if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 889d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 8905a30d8a2SDavid Howells path->dentry->d_inode) 8919875cf80SDavid Howells return -EISDIR; 8920ec26fd0SMiklos Szeredi 8939875cf80SDavid Howells current->total_link_count++; 8949875cf80SDavid Howells if (current->total_link_count >= 40) 8959875cf80SDavid Howells return -ELOOP; 8969875cf80SDavid Howells 8979875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 8989875cf80SDavid Howells if (IS_ERR(mnt)) { 8999875cf80SDavid Howells /* 9009875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 9019875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 9029875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 9039875cf80SDavid Howells * 9049875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 9059875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 9069875cf80SDavid Howells * the path is inaccessible and we should say so. 9079875cf80SDavid Howells */ 90849084c3bSAl Viro if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) 9099875cf80SDavid Howells return -EREMOTE; 9109875cf80SDavid Howells return PTR_ERR(mnt); 91131e6b01fSNick Piggin } 912ea5b778aSDavid Howells 9139875cf80SDavid Howells if (!mnt) /* mount collision */ 9149875cf80SDavid Howells return 0; 9159875cf80SDavid Howells 9168aef1884SAl Viro if (!*need_mntput) { 9178aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 9188aef1884SAl Viro mntget(path->mnt); 9198aef1884SAl Viro *need_mntput = true; 9208aef1884SAl Viro } 92119a167afSAl Viro err = finish_automount(mnt, path); 922ea5b778aSDavid Howells 923ea5b778aSDavid Howells switch (err) { 924ea5b778aSDavid Howells case -EBUSY: 925ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 92619a167afSAl Viro return 0; 927ea5b778aSDavid Howells case 0: 9288aef1884SAl Viro path_put(path); 9299875cf80SDavid Howells path->mnt = mnt; 9309875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 9319875cf80SDavid Howells return 0; 93219a167afSAl Viro default: 93319a167afSAl Viro return err; 9349875cf80SDavid Howells } 93519a167afSAl Viro 936ea5b778aSDavid Howells } 9379875cf80SDavid Howells 9389875cf80SDavid Howells /* 9399875cf80SDavid Howells * Handle a dentry that is managed in some way. 940cc53ce53SDavid Howells * - Flagged for transit management (autofs) 9419875cf80SDavid Howells * - Flagged as mountpoint 9429875cf80SDavid Howells * - Flagged as automount point 9439875cf80SDavid Howells * 9449875cf80SDavid Howells * This may only be called in refwalk mode. 9459875cf80SDavid Howells * 9469875cf80SDavid Howells * Serialization is taken care of in namespace.c 9479875cf80SDavid Howells */ 9489875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 9499875cf80SDavid Howells { 9508aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 9519875cf80SDavid Howells unsigned managed; 9529875cf80SDavid Howells bool need_mntput = false; 9538aef1884SAl Viro int ret = 0; 9549875cf80SDavid Howells 9559875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 9569875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 9579875cf80SDavid Howells * the components of that value change under us */ 9589875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 9599875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 9609875cf80SDavid Howells unlikely(managed != 0)) { 961cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 962cc53ce53SDavid Howells * being held. */ 963cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 964cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 965cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 9661aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 967cc53ce53SDavid Howells if (ret < 0) 9688aef1884SAl Viro break; 969cc53ce53SDavid Howells } 970cc53ce53SDavid Howells 9719875cf80SDavid Howells /* Transit to a mounted filesystem. */ 9729875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 9739875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 9749875cf80SDavid Howells if (mounted) { 9759875cf80SDavid Howells dput(path->dentry); 9769875cf80SDavid Howells if (need_mntput) 977463ffb2eSAl Viro mntput(path->mnt); 978463ffb2eSAl Viro path->mnt = mounted; 979463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 9809875cf80SDavid Howells need_mntput = true; 9819875cf80SDavid Howells continue; 982463ffb2eSAl Viro } 983463ffb2eSAl Viro 9849875cf80SDavid Howells /* Something is mounted on this dentry in another 9859875cf80SDavid Howells * namespace and/or whatever was mounted there in this 9869875cf80SDavid Howells * namespace got unmounted before we managed to get the 9879875cf80SDavid Howells * vfsmount_lock */ 9881da177e4SLinus Torvalds } 9899875cf80SDavid Howells 9909875cf80SDavid Howells /* Handle an automount point */ 9919875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 9929875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 9939875cf80SDavid Howells if (ret < 0) 9948aef1884SAl Viro break; 9959875cf80SDavid Howells continue; 9969875cf80SDavid Howells } 9979875cf80SDavid Howells 9989875cf80SDavid Howells /* We didn't change the current path point */ 9999875cf80SDavid Howells break; 10009875cf80SDavid Howells } 10018aef1884SAl Viro 10028aef1884SAl Viro if (need_mntput && path->mnt == mnt) 10038aef1884SAl Viro mntput(path->mnt); 10048aef1884SAl Viro if (ret == -EISDIR) 10058aef1884SAl Viro ret = 0; 1006a3fbbde7SAl Viro return ret < 0 ? ret : need_mntput; 10071da177e4SLinus Torvalds } 10081da177e4SLinus Torvalds 1009cc53ce53SDavid Howells int follow_down_one(struct path *path) 10101da177e4SLinus Torvalds { 10111da177e4SLinus Torvalds struct vfsmount *mounted; 10121da177e4SLinus Torvalds 10131c755af4SAl Viro mounted = lookup_mnt(path); 10141da177e4SLinus Torvalds if (mounted) { 10159393bd07SAl Viro dput(path->dentry); 10169393bd07SAl Viro mntput(path->mnt); 10179393bd07SAl Viro path->mnt = mounted; 10189393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 10191da177e4SLinus Torvalds return 1; 10201da177e4SLinus Torvalds } 10211da177e4SLinus Torvalds return 0; 10221da177e4SLinus Torvalds } 10231da177e4SLinus Torvalds 102462a7375eSIan Kent static inline bool managed_dentry_might_block(struct dentry *dentry) 102562a7375eSIan Kent { 102662a7375eSIan Kent return (dentry->d_flags & DCACHE_MANAGE_TRANSIT && 102762a7375eSIan Kent dentry->d_op->d_manage(dentry, true) < 0); 102862a7375eSIan Kent } 102962a7375eSIan Kent 10309875cf80SDavid Howells /* 1031287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1032287548e4SAl Viro * we meet a managed dentry that would need blocking. 10339875cf80SDavid Howells */ 10349875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1035287548e4SAl Viro struct inode **inode) 10369875cf80SDavid Howells { 103762a7375eSIan Kent for (;;) { 1038c7105365SAl Viro struct mount *mounted; 103962a7375eSIan Kent /* 104062a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 104162a7375eSIan Kent * that wants to block transit. 104262a7375eSIan Kent */ 1043287548e4SAl Viro if (unlikely(managed_dentry_might_block(path->dentry))) 1044ab90911fSDavid Howells return false; 104562a7375eSIan Kent 104662a7375eSIan Kent if (!d_mountpoint(path->dentry)) 104762a7375eSIan Kent break; 104862a7375eSIan Kent 10499875cf80SDavid Howells mounted = __lookup_mnt(path->mnt, path->dentry, 1); 10509875cf80SDavid Howells if (!mounted) 10519875cf80SDavid Howells break; 1052c7105365SAl Viro path->mnt = &mounted->mnt; 1053c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1054a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 10559875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 105659430262SLinus Torvalds /* 105759430262SLinus Torvalds * Update the inode too. We don't need to re-check the 105859430262SLinus Torvalds * dentry sequence number here after this d_inode read, 105959430262SLinus Torvalds * because a mount-point is always pinned. 106059430262SLinus Torvalds */ 106159430262SLinus Torvalds *inode = path->dentry->d_inode; 10629875cf80SDavid Howells } 10639875cf80SDavid Howells return true; 10649875cf80SDavid Howells } 10659875cf80SDavid Howells 1066dea39376SAl Viro static void follow_mount_rcu(struct nameidata *nd) 1067287548e4SAl Viro { 1068dea39376SAl Viro while (d_mountpoint(nd->path.dentry)) { 1069c7105365SAl Viro struct mount *mounted; 1070dea39376SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1); 1071287548e4SAl Viro if (!mounted) 1072287548e4SAl Viro break; 1073c7105365SAl Viro nd->path.mnt = &mounted->mnt; 1074c7105365SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 1075dea39376SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1076287548e4SAl Viro } 1077287548e4SAl Viro } 1078287548e4SAl Viro 107931e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 108031e6b01fSNick Piggin { 108131e6b01fSNick Piggin set_root_rcu(nd); 108231e6b01fSNick Piggin 108331e6b01fSNick Piggin while (1) { 108431e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 108531e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 108631e6b01fSNick Piggin break; 108731e6b01fSNick Piggin } 108831e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 108931e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 109031e6b01fSNick Piggin struct dentry *parent = old->d_parent; 109131e6b01fSNick Piggin unsigned seq; 109231e6b01fSNick Piggin 109331e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 109431e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1095ef7562d5SAl Viro goto failed; 109631e6b01fSNick Piggin nd->path.dentry = parent; 109731e6b01fSNick Piggin nd->seq = seq; 109831e6b01fSNick Piggin break; 109931e6b01fSNick Piggin } 110031e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 110131e6b01fSNick Piggin break; 110231e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 110331e6b01fSNick Piggin } 1104dea39376SAl Viro follow_mount_rcu(nd); 1105dea39376SAl Viro nd->inode = nd->path.dentry->d_inode; 110631e6b01fSNick Piggin return 0; 1107ef7562d5SAl Viro 1108ef7562d5SAl Viro failed: 1109ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 11105b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1111ef7562d5SAl Viro nd->root.mnt = NULL; 111232a7991bSAl Viro unlock_rcu_walk(); 1113ef7562d5SAl Viro return -ECHILD; 111431e6b01fSNick Piggin } 111531e6b01fSNick Piggin 11169875cf80SDavid Howells /* 1117cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1118cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1119cc53ce53SDavid Howells * caller is permitted to proceed or not. 1120cc53ce53SDavid Howells */ 11217cc90cc3SAl Viro int follow_down(struct path *path) 1122cc53ce53SDavid Howells { 1123cc53ce53SDavid Howells unsigned managed; 1124cc53ce53SDavid Howells int ret; 1125cc53ce53SDavid Howells 1126cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1127cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1128cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1129cc53ce53SDavid Howells * being held. 1130cc53ce53SDavid Howells * 1131cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1132cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1133cc53ce53SDavid Howells * other than its daemon the right to mount on its 1134cc53ce53SDavid Howells * superstructure. 1135cc53ce53SDavid Howells * 1136cc53ce53SDavid Howells * The filesystem may sleep at this point. 1137cc53ce53SDavid Howells */ 1138cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1139cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1140cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1141ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 11421aed3e42SAl Viro path->dentry, false); 1143cc53ce53SDavid Howells if (ret < 0) 1144cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1145cc53ce53SDavid Howells } 1146cc53ce53SDavid Howells 1147cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1148cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1149cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1150cc53ce53SDavid Howells if (!mounted) 1151cc53ce53SDavid Howells break; 1152cc53ce53SDavid Howells dput(path->dentry); 1153cc53ce53SDavid Howells mntput(path->mnt); 1154cc53ce53SDavid Howells path->mnt = mounted; 1155cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1156cc53ce53SDavid Howells continue; 1157cc53ce53SDavid Howells } 1158cc53ce53SDavid Howells 1159cc53ce53SDavid Howells /* Don't handle automount points here */ 1160cc53ce53SDavid Howells break; 1161cc53ce53SDavid Howells } 1162cc53ce53SDavid Howells return 0; 1163cc53ce53SDavid Howells } 1164cc53ce53SDavid Howells 1165cc53ce53SDavid Howells /* 11669875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 11679875cf80SDavid Howells */ 11689875cf80SDavid Howells static void follow_mount(struct path *path) 11699875cf80SDavid Howells { 11709875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 11719875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 11729875cf80SDavid Howells if (!mounted) 11739875cf80SDavid Howells break; 11749875cf80SDavid Howells dput(path->dentry); 11759875cf80SDavid Howells mntput(path->mnt); 11769875cf80SDavid Howells path->mnt = mounted; 11779875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 11789875cf80SDavid Howells } 11799875cf80SDavid Howells } 11809875cf80SDavid Howells 118131e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 11821da177e4SLinus Torvalds { 11832a737871SAl Viro set_root(nd); 1184e518ddb7SAndreas Mohr 11851da177e4SLinus Torvalds while(1) { 11864ac91378SJan Blunck struct dentry *old = nd->path.dentry; 11871da177e4SLinus Torvalds 11882a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 11892a737871SAl Viro nd->path.mnt == nd->root.mnt) { 11901da177e4SLinus Torvalds break; 11911da177e4SLinus Torvalds } 11924ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 11933088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 11943088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 11951da177e4SLinus Torvalds dput(old); 11961da177e4SLinus Torvalds break; 11971da177e4SLinus Torvalds } 11983088dd70SAl Viro if (!follow_up(&nd->path)) 11991da177e4SLinus Torvalds break; 12001da177e4SLinus Torvalds } 120179ed0226SAl Viro follow_mount(&nd->path); 120231e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 12031da177e4SLinus Torvalds } 12041da177e4SLinus Torvalds 12051da177e4SLinus Torvalds /* 1206bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1207bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1208bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1209bad61189SMiklos Szeredi * 1210bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1211baa03890SNick Piggin */ 1212bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1213201f956eSAl Viro unsigned int flags, bool *need_lookup) 1214baa03890SNick Piggin { 1215baa03890SNick Piggin struct dentry *dentry; 1216bad61189SMiklos Szeredi int error; 1217baa03890SNick Piggin 1218bad61189SMiklos Szeredi *need_lookup = false; 1219bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1220bad61189SMiklos Szeredi if (dentry) { 1221bad61189SMiklos Szeredi if (d_need_lookup(dentry)) { 1222bad61189SMiklos Szeredi *need_lookup = true; 1223bad61189SMiklos Szeredi } else if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1224201f956eSAl Viro error = d_revalidate(dentry, flags); 1225bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1226bad61189SMiklos Szeredi if (error < 0) { 1227bad61189SMiklos Szeredi dput(dentry); 1228bad61189SMiklos Szeredi return ERR_PTR(error); 1229bad61189SMiklos Szeredi } else if (!d_invalidate(dentry)) { 1230bad61189SMiklos Szeredi dput(dentry); 1231bad61189SMiklos Szeredi dentry = NULL; 1232bad61189SMiklos Szeredi } 1233bad61189SMiklos Szeredi } 1234bad61189SMiklos Szeredi } 1235bad61189SMiklos Szeredi } 1236baa03890SNick Piggin 1237bad61189SMiklos Szeredi if (!dentry) { 1238bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1239baa03890SNick Piggin if (unlikely(!dentry)) 1240baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1241baa03890SNick Piggin 1242bad61189SMiklos Szeredi *need_lookup = true; 1243baa03890SNick Piggin } 1244baa03890SNick Piggin return dentry; 1245baa03890SNick Piggin } 1246baa03890SNick Piggin 1247baa03890SNick Piggin /* 1248bad61189SMiklos Szeredi * Call i_op->lookup on the dentry. The dentry must be negative but may be 1249bad61189SMiklos Szeredi * hashed if it was pouplated with DCACHE_NEED_LOOKUP. 1250bad61189SMiklos Szeredi * 1251bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 125244396f4bSJosef Bacik */ 1253bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 125472bd866aSAl Viro unsigned int flags) 125544396f4bSJosef Bacik { 125644396f4bSJosef Bacik struct dentry *old; 125744396f4bSJosef Bacik 125844396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1259bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1260e188dc02SMiklos Szeredi dput(dentry); 126144396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1262e188dc02SMiklos Szeredi } 126344396f4bSJosef Bacik 126472bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 126544396f4bSJosef Bacik if (unlikely(old)) { 126644396f4bSJosef Bacik dput(dentry); 126744396f4bSJosef Bacik dentry = old; 126844396f4bSJosef Bacik } 126944396f4bSJosef Bacik return dentry; 127044396f4bSJosef Bacik } 127144396f4bSJosef Bacik 1272a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 127372bd866aSAl Viro struct dentry *base, unsigned int flags) 1274a3255546SAl Viro { 1275bad61189SMiklos Szeredi bool need_lookup; 1276a3255546SAl Viro struct dentry *dentry; 1277a3255546SAl Viro 127872bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1279bad61189SMiklos Szeredi if (!need_lookup) 1280a3255546SAl Viro return dentry; 1281bad61189SMiklos Szeredi 128272bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1283a3255546SAl Viro } 1284a3255546SAl Viro 128544396f4bSJosef Bacik /* 12861da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 12871da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 12881da177e4SLinus Torvalds * It _is_ time-critical. 12891da177e4SLinus Torvalds */ 1290697f514dSMiklos Szeredi static int lookup_fast(struct nameidata *nd, struct qstr *name, 129131e6b01fSNick Piggin struct path *path, struct inode **inode) 12921da177e4SLinus Torvalds { 12934ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 129431e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 12955a18fff2SAl Viro int need_reval = 1; 12965a18fff2SAl Viro int status = 1; 12979875cf80SDavid Howells int err; 12989875cf80SDavid Howells 12993cac260aSAl Viro /* 1300b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1301b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1302b04f784eSNick Piggin * do the non-racy lookup, below. 1303b04f784eSNick Piggin */ 130431e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 130531e6b01fSNick Piggin unsigned seq; 130612f8ad4bSLinus Torvalds dentry = __d_lookup_rcu(parent, name, &seq, nd->inode); 13075a18fff2SAl Viro if (!dentry) 13085a18fff2SAl Viro goto unlazy; 13095a18fff2SAl Viro 131012f8ad4bSLinus Torvalds /* 131112f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 131212f8ad4bSLinus Torvalds * the dentry name information from lookup. 131312f8ad4bSLinus Torvalds */ 131412f8ad4bSLinus Torvalds *inode = dentry->d_inode; 131512f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 131612f8ad4bSLinus Torvalds return -ECHILD; 131712f8ad4bSLinus Torvalds 131812f8ad4bSLinus Torvalds /* 131912f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 132012f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 132112f8ad4bSLinus Torvalds * 132212f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 132312f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 132412f8ad4bSLinus Torvalds */ 132531e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 132631e6b01fSNick Piggin return -ECHILD; 132731e6b01fSNick Piggin nd->seq = seq; 13285a18fff2SAl Viro 1329fa4ee159SMiklos Szeredi if (unlikely(d_need_lookup(dentry))) 1330fa4ee159SMiklos Szeredi goto unlazy; 133124643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 13324ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 13335a18fff2SAl Viro if (unlikely(status <= 0)) { 13345a18fff2SAl Viro if (status != -ECHILD) 13355a18fff2SAl Viro need_reval = 0; 13365a18fff2SAl Viro goto unlazy; 13375a18fff2SAl Viro } 133824643087SAl Viro } 133931e6b01fSNick Piggin path->mnt = mnt; 134031e6b01fSNick Piggin path->dentry = dentry; 1341d6e9bd25SAl Viro if (unlikely(!__follow_mount_rcu(nd, path, inode))) 1342d6e9bd25SAl Viro goto unlazy; 1343d6e9bd25SAl Viro if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) 1344d6e9bd25SAl Viro goto unlazy; 13459875cf80SDavid Howells return 0; 13465a18fff2SAl Viro unlazy: 134719660af7SAl Viro if (unlazy_walk(nd, dentry)) 13485a18fff2SAl Viro return -ECHILD; 13495a18fff2SAl Viro } else { 135031e6b01fSNick Piggin dentry = __d_lookup(parent, name); 135124643087SAl Viro } 13525a18fff2SAl Viro 135381e6f520SAl Viro if (unlikely(!dentry)) 135481e6f520SAl Viro goto need_lookup; 13555a18fff2SAl Viro 135681e6f520SAl Viro if (unlikely(d_need_lookup(dentry))) { 135781e6f520SAl Viro dput(dentry); 135881e6f520SAl Viro goto need_lookup; 13595a18fff2SAl Viro } 136081e6f520SAl Viro 13615a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 13624ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 13635a18fff2SAl Viro if (unlikely(status <= 0)) { 13645a18fff2SAl Viro if (status < 0) { 13655a18fff2SAl Viro dput(dentry); 13665a18fff2SAl Viro return status; 13675a18fff2SAl Viro } 13685a18fff2SAl Viro if (!d_invalidate(dentry)) { 13695a18fff2SAl Viro dput(dentry); 137081e6f520SAl Viro goto need_lookup; 13715a18fff2SAl Viro } 13725a18fff2SAl Viro } 1373697f514dSMiklos Szeredi 13741da177e4SLinus Torvalds path->mnt = mnt; 13751da177e4SLinus Torvalds path->dentry = dentry; 13769875cf80SDavid Howells err = follow_managed(path, nd->flags); 137789312214SIan Kent if (unlikely(err < 0)) { 137889312214SIan Kent path_put_conditional(path, nd); 13799875cf80SDavid Howells return err; 138089312214SIan Kent } 1381a3fbbde7SAl Viro if (err) 1382a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 138331e6b01fSNick Piggin *inode = path->dentry->d_inode; 13841da177e4SLinus Torvalds return 0; 138581e6f520SAl Viro 138681e6f520SAl Viro need_lookup: 1387697f514dSMiklos Szeredi return 1; 1388697f514dSMiklos Szeredi } 1389697f514dSMiklos Szeredi 1390697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1391697f514dSMiklos Szeredi static int lookup_slow(struct nameidata *nd, struct qstr *name, 1392697f514dSMiklos Szeredi struct path *path) 1393697f514dSMiklos Szeredi { 1394697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1395697f514dSMiklos Szeredi int err; 1396697f514dSMiklos Szeredi 1397697f514dSMiklos Szeredi parent = nd->path.dentry; 139881e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 139981e6f520SAl Viro 140081e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 140172bd866aSAl Viro dentry = __lookup_hash(name, parent, nd->flags); 140281e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 140381e6f520SAl Viro if (IS_ERR(dentry)) 140481e6f520SAl Viro return PTR_ERR(dentry); 1405697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1406697f514dSMiklos Szeredi path->dentry = dentry; 1407697f514dSMiklos Szeredi err = follow_managed(path, nd->flags); 1408697f514dSMiklos Szeredi if (unlikely(err < 0)) { 1409697f514dSMiklos Szeredi path_put_conditional(path, nd); 1410697f514dSMiklos Szeredi return err; 1411697f514dSMiklos Szeredi } 1412697f514dSMiklos Szeredi if (err) 1413697f514dSMiklos Szeredi nd->flags |= LOOKUP_JUMPED; 1414697f514dSMiklos Szeredi return 0; 14151da177e4SLinus Torvalds } 14161da177e4SLinus Torvalds 141752094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 141852094c8aSAl Viro { 141952094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 14204ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 142152094c8aSAl Viro if (err != -ECHILD) 142252094c8aSAl Viro return err; 142319660af7SAl Viro if (unlazy_walk(nd, NULL)) 142452094c8aSAl Viro return -ECHILD; 142552094c8aSAl Viro } 14264ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 142752094c8aSAl Viro } 142852094c8aSAl Viro 14299856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 14309856fa1bSAl Viro { 14319856fa1bSAl Viro if (type == LAST_DOTDOT) { 14329856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 14339856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 14349856fa1bSAl Viro return -ECHILD; 14359856fa1bSAl Viro } else 14369856fa1bSAl Viro follow_dotdot(nd); 14379856fa1bSAl Viro } 14389856fa1bSAl Viro return 0; 14399856fa1bSAl Viro } 14409856fa1bSAl Viro 1441951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1442951361f9SAl Viro { 1443951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1444951361f9SAl Viro path_put(&nd->path); 1445951361f9SAl Viro } else { 1446951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 14475b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1448951361f9SAl Viro nd->root.mnt = NULL; 144932a7991bSAl Viro unlock_rcu_walk(); 1450951361f9SAl Viro } 1451951361f9SAl Viro } 1452951361f9SAl Viro 14533ddcd056SLinus Torvalds /* 14543ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 14553ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 14563ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 14573ddcd056SLinus Torvalds * for the common case. 14583ddcd056SLinus Torvalds */ 14597813b94aSLinus Torvalds static inline int should_follow_link(struct inode *inode, int follow) 14603ddcd056SLinus Torvalds { 14613ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) { 14623ddcd056SLinus Torvalds if (likely(inode->i_op->follow_link)) 14633ddcd056SLinus Torvalds return follow; 14643ddcd056SLinus Torvalds 14653ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 14663ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 14673ddcd056SLinus Torvalds inode->i_opflags |= IOP_NOFOLLOW; 14683ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 14693ddcd056SLinus Torvalds } 14703ddcd056SLinus Torvalds return 0; 14713ddcd056SLinus Torvalds } 14723ddcd056SLinus Torvalds 1473ce57dfc1SAl Viro static inline int walk_component(struct nameidata *nd, struct path *path, 1474ce57dfc1SAl Viro struct qstr *name, int type, int follow) 1475ce57dfc1SAl Viro { 1476ce57dfc1SAl Viro struct inode *inode; 1477ce57dfc1SAl Viro int err; 1478ce57dfc1SAl Viro /* 1479ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1480ce57dfc1SAl Viro * to be able to know about the current root directory and 1481ce57dfc1SAl Viro * parent relationships. 1482ce57dfc1SAl Viro */ 1483ce57dfc1SAl Viro if (unlikely(type != LAST_NORM)) 1484ce57dfc1SAl Viro return handle_dots(nd, type); 1485697f514dSMiklos Szeredi err = lookup_fast(nd, name, path, &inode); 1486ce57dfc1SAl Viro if (unlikely(err)) { 1487697f514dSMiklos Szeredi if (err < 0) 1488697f514dSMiklos Szeredi goto out_err; 1489697f514dSMiklos Szeredi 1490697f514dSMiklos Szeredi err = lookup_slow(nd, name, path); 1491697f514dSMiklos Szeredi if (err < 0) 1492697f514dSMiklos Szeredi goto out_err; 1493697f514dSMiklos Szeredi 1494697f514dSMiklos Szeredi inode = path->dentry->d_inode; 1495ce57dfc1SAl Viro } 1496697f514dSMiklos Szeredi err = -ENOENT; 1497697f514dSMiklos Szeredi if (!inode) 1498697f514dSMiklos Szeredi goto out_path_put; 1499697f514dSMiklos Szeredi 15007813b94aSLinus Torvalds if (should_follow_link(inode, follow)) { 150119660af7SAl Viro if (nd->flags & LOOKUP_RCU) { 150219660af7SAl Viro if (unlikely(unlazy_walk(nd, path->dentry))) { 1503697f514dSMiklos Szeredi err = -ECHILD; 1504697f514dSMiklos Szeredi goto out_err; 150519660af7SAl Viro } 150619660af7SAl Viro } 1507ce57dfc1SAl Viro BUG_ON(inode != path->dentry->d_inode); 1508ce57dfc1SAl Viro return 1; 1509ce57dfc1SAl Viro } 1510ce57dfc1SAl Viro path_to_nameidata(path, nd); 1511ce57dfc1SAl Viro nd->inode = inode; 1512ce57dfc1SAl Viro return 0; 1513697f514dSMiklos Szeredi 1514697f514dSMiklos Szeredi out_path_put: 1515697f514dSMiklos Szeredi path_to_nameidata(path, nd); 1516697f514dSMiklos Szeredi out_err: 1517697f514dSMiklos Szeredi terminate_walk(nd); 1518697f514dSMiklos Szeredi return err; 1519ce57dfc1SAl Viro } 1520ce57dfc1SAl Viro 15211da177e4SLinus Torvalds /* 1522b356379aSAl Viro * This limits recursive symlink follows to 8, while 1523b356379aSAl Viro * limiting consecutive symlinks to 40. 1524b356379aSAl Viro * 1525b356379aSAl Viro * Without that kind of total limit, nasty chains of consecutive 1526b356379aSAl Viro * symlinks can cause almost arbitrarily long lookups. 1527b356379aSAl Viro */ 1528b356379aSAl Viro static inline int nested_symlink(struct path *path, struct nameidata *nd) 1529b356379aSAl Viro { 1530b356379aSAl Viro int res; 1531b356379aSAl Viro 1532b356379aSAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 1533b356379aSAl Viro path_put_conditional(path, nd); 1534b356379aSAl Viro path_put(&nd->path); 1535b356379aSAl Viro return -ELOOP; 1536b356379aSAl Viro } 15371a4022f8SErez Zadok BUG_ON(nd->depth >= MAX_NESTED_LINKS); 1538b356379aSAl Viro 1539b356379aSAl Viro nd->depth++; 1540b356379aSAl Viro current->link_count++; 1541b356379aSAl Viro 1542b356379aSAl Viro do { 1543b356379aSAl Viro struct path link = *path; 1544b356379aSAl Viro void *cookie; 1545574197e0SAl Viro 1546574197e0SAl Viro res = follow_link(&link, nd, &cookie); 15476d7b5aaeSAl Viro if (res) 15486d7b5aaeSAl Viro break; 1549b356379aSAl Viro res = walk_component(nd, path, &nd->last, 1550b356379aSAl Viro nd->last_type, LOOKUP_FOLLOW); 1551574197e0SAl Viro put_link(nd, &link, cookie); 1552b356379aSAl Viro } while (res > 0); 1553b356379aSAl Viro 1554b356379aSAl Viro current->link_count--; 1555b356379aSAl Viro nd->depth--; 1556b356379aSAl Viro return res; 1557b356379aSAl Viro } 1558b356379aSAl Viro 1559b356379aSAl Viro /* 15603ddcd056SLinus Torvalds * We really don't want to look at inode->i_op->lookup 15613ddcd056SLinus Torvalds * when we don't have to. So we keep a cache bit in 15623ddcd056SLinus Torvalds * the inode ->i_opflags field that says "yes, we can 15633ddcd056SLinus Torvalds * do lookup on this inode". 15643ddcd056SLinus Torvalds */ 15653ddcd056SLinus Torvalds static inline int can_lookup(struct inode *inode) 15663ddcd056SLinus Torvalds { 15673ddcd056SLinus Torvalds if (likely(inode->i_opflags & IOP_LOOKUP)) 15683ddcd056SLinus Torvalds return 1; 15693ddcd056SLinus Torvalds if (likely(!inode->i_op->lookup)) 15703ddcd056SLinus Torvalds return 0; 15713ddcd056SLinus Torvalds 15723ddcd056SLinus Torvalds /* We do this once for the lifetime of the inode */ 15733ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 15743ddcd056SLinus Torvalds inode->i_opflags |= IOP_LOOKUP; 15753ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 15763ddcd056SLinus Torvalds return 1; 15773ddcd056SLinus Torvalds } 15783ddcd056SLinus Torvalds 1579bfcfaa77SLinus Torvalds /* 1580bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1581bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1582bfcfaa77SLinus Torvalds * 1583bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1584bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1585bfcfaa77SLinus Torvalds * fast. 1586bfcfaa77SLinus Torvalds * 1587bfcfaa77SLinus Torvalds * - Little-endian machines (so that we can generate the mask 1588bfcfaa77SLinus Torvalds * of low bytes efficiently). Again, we *could* do a byte 1589bfcfaa77SLinus Torvalds * swapping load on big-endian architectures if that is not 1590bfcfaa77SLinus Torvalds * expensive enough to make the optimization worthless. 1591bfcfaa77SLinus Torvalds * 1592bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1593bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1594bfcfaa77SLinus Torvalds * crossing operation. 1595bfcfaa77SLinus Torvalds * 1596bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1597bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1598bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1599bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1600bfcfaa77SLinus Torvalds */ 1601bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1602bfcfaa77SLinus Torvalds 1603f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1604bfcfaa77SLinus Torvalds 1605f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1606bfcfaa77SLinus Torvalds 1607bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1608bfcfaa77SLinus Torvalds { 1609bfcfaa77SLinus Torvalds hash += hash >> (8*sizeof(int)); 1610bfcfaa77SLinus Torvalds return hash; 1611bfcfaa77SLinus Torvalds } 1612bfcfaa77SLinus Torvalds 1613bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1614bfcfaa77SLinus Torvalds 1615bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1616bfcfaa77SLinus Torvalds 1617bfcfaa77SLinus Torvalds #endif 1618bfcfaa77SLinus Torvalds 1619bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1620bfcfaa77SLinus Torvalds { 1621bfcfaa77SLinus Torvalds unsigned long a, mask; 1622bfcfaa77SLinus Torvalds unsigned long hash = 0; 1623bfcfaa77SLinus Torvalds 1624bfcfaa77SLinus Torvalds for (;;) { 1625e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1626bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1627bfcfaa77SLinus Torvalds break; 1628bfcfaa77SLinus Torvalds hash += a; 1629f132c5beSAl Viro hash *= 9; 1630bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1631bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1632bfcfaa77SLinus Torvalds if (!len) 1633bfcfaa77SLinus Torvalds goto done; 1634bfcfaa77SLinus Torvalds } 1635bfcfaa77SLinus Torvalds mask = ~(~0ul << len*8); 1636bfcfaa77SLinus Torvalds hash += mask & a; 1637bfcfaa77SLinus Torvalds done: 1638bfcfaa77SLinus Torvalds return fold_hash(hash); 1639bfcfaa77SLinus Torvalds } 1640bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1641bfcfaa77SLinus Torvalds 1642bfcfaa77SLinus Torvalds /* 1643bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1644bfcfaa77SLinus Torvalds * return the length of the component; 1645bfcfaa77SLinus Torvalds */ 1646bfcfaa77SLinus Torvalds static inline unsigned long hash_name(const char *name, unsigned int *hashp) 1647bfcfaa77SLinus Torvalds { 164836126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 164936126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1650bfcfaa77SLinus Torvalds 1651bfcfaa77SLinus Torvalds hash = a = 0; 1652bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1653bfcfaa77SLinus Torvalds do { 1654bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1655bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1656e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 165736126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 165836126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1659bfcfaa77SLinus Torvalds 166036126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 166136126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 166236126f8fSLinus Torvalds 166336126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 166436126f8fSLinus Torvalds 166536126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 1666bfcfaa77SLinus Torvalds *hashp = fold_hash(hash); 1667bfcfaa77SLinus Torvalds 166836126f8fSLinus Torvalds return len + find_zero(mask); 1669bfcfaa77SLinus Torvalds } 1670bfcfaa77SLinus Torvalds 1671bfcfaa77SLinus Torvalds #else 1672bfcfaa77SLinus Torvalds 16730145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 16740145acc2SLinus Torvalds { 16750145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 16760145acc2SLinus Torvalds while (len--) 16770145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 16780145acc2SLinus Torvalds return end_name_hash(hash); 16790145acc2SLinus Torvalds } 1680ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 16810145acc2SLinus Torvalds 16823ddcd056SLinus Torvalds /* 1683200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1684200e9ef7SLinus Torvalds * one character. 1685200e9ef7SLinus Torvalds */ 1686200e9ef7SLinus Torvalds static inline unsigned long hash_name(const char *name, unsigned int *hashp) 1687200e9ef7SLinus Torvalds { 1688200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1689200e9ef7SLinus Torvalds unsigned long len = 0, c; 1690200e9ef7SLinus Torvalds 1691200e9ef7SLinus Torvalds c = (unsigned char)*name; 1692200e9ef7SLinus Torvalds do { 1693200e9ef7SLinus Torvalds len++; 1694200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1695200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1696200e9ef7SLinus Torvalds } while (c && c != '/'); 1697200e9ef7SLinus Torvalds *hashp = end_name_hash(hash); 1698200e9ef7SLinus Torvalds return len; 1699200e9ef7SLinus Torvalds } 1700200e9ef7SLinus Torvalds 1701bfcfaa77SLinus Torvalds #endif 1702bfcfaa77SLinus Torvalds 1703200e9ef7SLinus Torvalds /* 17041da177e4SLinus Torvalds * Name resolution. 1705ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1706ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 17071da177e4SLinus Torvalds * 1708ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1709ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 17101da177e4SLinus Torvalds */ 17116de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 17121da177e4SLinus Torvalds { 17131da177e4SLinus Torvalds struct path next; 17141da177e4SLinus Torvalds int err; 17151da177e4SLinus Torvalds 17161da177e4SLinus Torvalds while (*name=='/') 17171da177e4SLinus Torvalds name++; 17181da177e4SLinus Torvalds if (!*name) 1719086e183aSAl Viro return 0; 17201da177e4SLinus Torvalds 17211da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 17221da177e4SLinus Torvalds for(;;) { 17231da177e4SLinus Torvalds struct qstr this; 1724200e9ef7SLinus Torvalds long len; 1725fe479a58SAl Viro int type; 17261da177e4SLinus Torvalds 172752094c8aSAl Viro err = may_lookup(nd); 17281da177e4SLinus Torvalds if (err) 17291da177e4SLinus Torvalds break; 17301da177e4SLinus Torvalds 1731200e9ef7SLinus Torvalds len = hash_name(name, &this.hash); 17321da177e4SLinus Torvalds this.name = name; 1733200e9ef7SLinus Torvalds this.len = len; 17341da177e4SLinus Torvalds 1735fe479a58SAl Viro type = LAST_NORM; 1736200e9ef7SLinus Torvalds if (name[0] == '.') switch (len) { 1737fe479a58SAl Viro case 2: 1738200e9ef7SLinus Torvalds if (name[1] == '.') { 1739fe479a58SAl Viro type = LAST_DOTDOT; 174016c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 174116c2cd71SAl Viro } 1742fe479a58SAl Viro break; 1743fe479a58SAl Viro case 1: 1744fe479a58SAl Viro type = LAST_DOT; 1745fe479a58SAl Viro } 17465a202bcdSAl Viro if (likely(type == LAST_NORM)) { 17475a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 174816c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 17495a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 17505a202bcdSAl Viro err = parent->d_op->d_hash(parent, nd->inode, 17515a202bcdSAl Viro &this); 17525a202bcdSAl Viro if (err < 0) 17535a202bcdSAl Viro break; 17545a202bcdSAl Viro } 17555a202bcdSAl Viro } 1756fe479a58SAl Viro 1757200e9ef7SLinus Torvalds if (!name[len]) 17581da177e4SLinus Torvalds goto last_component; 1759200e9ef7SLinus Torvalds /* 1760200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1761200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1762200e9ef7SLinus Torvalds */ 1763200e9ef7SLinus Torvalds do { 1764200e9ef7SLinus Torvalds len++; 1765200e9ef7SLinus Torvalds } while (unlikely(name[len] == '/')); 1766200e9ef7SLinus Torvalds if (!name[len]) 1767b356379aSAl Viro goto last_component; 1768200e9ef7SLinus Torvalds name += len; 17691da177e4SLinus Torvalds 1770ce57dfc1SAl Viro err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW); 1771ce57dfc1SAl Viro if (err < 0) 1772ce57dfc1SAl Viro return err; 1773fe479a58SAl Viro 1774ce57dfc1SAl Viro if (err) { 1775b356379aSAl Viro err = nested_symlink(&next, nd); 17761da177e4SLinus Torvalds if (err) 1777a7472babSAl Viro return err; 177831e6b01fSNick Piggin } 17793ddcd056SLinus Torvalds if (can_lookup(nd->inode)) 17801da177e4SLinus Torvalds continue; 17813ddcd056SLinus Torvalds err = -ENOTDIR; 17823ddcd056SLinus Torvalds break; 17831da177e4SLinus Torvalds /* here ends the main loop */ 17841da177e4SLinus Torvalds 17851da177e4SLinus Torvalds last_component: 1786ce57dfc1SAl Viro nd->last = this; 1787ce57dfc1SAl Viro nd->last_type = type; 1788ce57dfc1SAl Viro return 0; 1789ce57dfc1SAl Viro } 1790951361f9SAl Viro terminate_walk(nd); 17911da177e4SLinus Torvalds return err; 17921da177e4SLinus Torvalds } 17931da177e4SLinus Torvalds 179470e9b357SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, 179570e9b357SAl Viro struct nameidata *nd, struct file **fp) 179631e6b01fSNick Piggin { 179731e6b01fSNick Piggin int retval = 0; 179831e6b01fSNick Piggin int fput_needed; 179931e6b01fSNick Piggin struct file *file; 180031e6b01fSNick Piggin 180131e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 180216c2cd71SAl Viro nd->flags = flags | LOOKUP_JUMPED; 180331e6b01fSNick Piggin nd->depth = 0; 18045b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 18055b6ca027SAl Viro struct inode *inode = nd->root.dentry->d_inode; 180673d049a4SAl Viro if (*name) { 18075b6ca027SAl Viro if (!inode->i_op->lookup) 18085b6ca027SAl Viro return -ENOTDIR; 18095b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 18105b6ca027SAl Viro if (retval) 18115b6ca027SAl Viro return retval; 181273d049a4SAl Viro } 18135b6ca027SAl Viro nd->path = nd->root; 18145b6ca027SAl Viro nd->inode = inode; 18155b6ca027SAl Viro if (flags & LOOKUP_RCU) { 181632a7991bSAl Viro lock_rcu_walk(); 18175b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 18185b6ca027SAl Viro } else { 18195b6ca027SAl Viro path_get(&nd->path); 18205b6ca027SAl Viro } 18215b6ca027SAl Viro return 0; 18225b6ca027SAl Viro } 18235b6ca027SAl Viro 182431e6b01fSNick Piggin nd->root.mnt = NULL; 182531e6b01fSNick Piggin 182631e6b01fSNick Piggin if (*name=='/') { 1827e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 182832a7991bSAl Viro lock_rcu_walk(); 1829e41f7d4eSAl Viro set_root_rcu(nd); 1830e41f7d4eSAl Viro } else { 1831e41f7d4eSAl Viro set_root(nd); 1832e41f7d4eSAl Viro path_get(&nd->root); 1833e41f7d4eSAl Viro } 183431e6b01fSNick Piggin nd->path = nd->root; 183531e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1836e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 183731e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1838c28cc364SNick Piggin unsigned seq; 183931e6b01fSNick Piggin 184032a7991bSAl Viro lock_rcu_walk(); 184131e6b01fSNick Piggin 1842c28cc364SNick Piggin do { 1843c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 184431e6b01fSNick Piggin nd->path = fs->pwd; 1845c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1846c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1847e41f7d4eSAl Viro } else { 1848e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1849e41f7d4eSAl Viro } 185031e6b01fSNick Piggin } else { 185131e6b01fSNick Piggin struct dentry *dentry; 185231e6b01fSNick Piggin 18531abf0c71SAl Viro file = fget_raw_light(dfd, &fput_needed); 185431e6b01fSNick Piggin retval = -EBADF; 185531e6b01fSNick Piggin if (!file) 185631e6b01fSNick Piggin goto out_fail; 185731e6b01fSNick Piggin 185831e6b01fSNick Piggin dentry = file->f_path.dentry; 185931e6b01fSNick Piggin 1860f52e0c11SAl Viro if (*name) { 186131e6b01fSNick Piggin retval = -ENOTDIR; 186231e6b01fSNick Piggin if (!S_ISDIR(dentry->d_inode->i_mode)) 186331e6b01fSNick Piggin goto fput_fail; 186431e6b01fSNick Piggin 18654ad5abb3SAl Viro retval = inode_permission(dentry->d_inode, MAY_EXEC); 186631e6b01fSNick Piggin if (retval) 186731e6b01fSNick Piggin goto fput_fail; 1868f52e0c11SAl Viro } 186931e6b01fSNick Piggin 187031e6b01fSNick Piggin nd->path = file->f_path; 1871e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 187231e6b01fSNick Piggin if (fput_needed) 187370e9b357SAl Viro *fp = file; 1874c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 187532a7991bSAl Viro lock_rcu_walk(); 18765590ff0dSUlrich Drepper } else { 18775dd784d0SJan Blunck path_get(&file->f_path); 18785590ff0dSUlrich Drepper fput_light(file, fput_needed); 18791da177e4SLinus Torvalds } 1880e41f7d4eSAl Viro } 1881e41f7d4eSAl Viro 188231e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 18839b4a9b14SAl Viro return 0; 18842dfdd266SJosef 'Jeff' Sipek 18859b4a9b14SAl Viro fput_fail: 18869b4a9b14SAl Viro fput_light(file, fput_needed); 18879b4a9b14SAl Viro out_fail: 18889b4a9b14SAl Viro return retval; 18899b4a9b14SAl Viro } 18909b4a9b14SAl Viro 1891bd92d7feSAl Viro static inline int lookup_last(struct nameidata *nd, struct path *path) 1892bd92d7feSAl Viro { 1893bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1894bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1895bd92d7feSAl Viro 1896bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 1897bd92d7feSAl Viro return walk_component(nd, path, &nd->last, nd->last_type, 1898bd92d7feSAl Viro nd->flags & LOOKUP_FOLLOW); 1899bd92d7feSAl Viro } 1900bd92d7feSAl Viro 19019b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1902ee0827cdSAl Viro static int path_lookupat(int dfd, const char *name, 19039b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 19049b4a9b14SAl Viro { 190570e9b357SAl Viro struct file *base = NULL; 1906bd92d7feSAl Viro struct path path; 1907bd92d7feSAl Viro int err; 190831e6b01fSNick Piggin 190931e6b01fSNick Piggin /* 191031e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 191131e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 191231e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 191331e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 191431e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 191531e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 191631e6b01fSNick Piggin * analogue, foo_rcu(). 191731e6b01fSNick Piggin * 191831e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 191931e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 192031e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 192131e6b01fSNick Piggin * be able to complete). 192231e6b01fSNick Piggin */ 1923bd92d7feSAl Viro err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); 1924ee0827cdSAl Viro 1925bd92d7feSAl Viro if (unlikely(err)) 1926bd92d7feSAl Viro return err; 1927ee0827cdSAl Viro 1928ee0827cdSAl Viro current->total_link_count = 0; 1929bd92d7feSAl Viro err = link_path_walk(name, nd); 1930bd92d7feSAl Viro 1931bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 1932bd92d7feSAl Viro err = lookup_last(nd, &path); 1933bd92d7feSAl Viro while (err > 0) { 1934bd92d7feSAl Viro void *cookie; 1935bd92d7feSAl Viro struct path link = path; 1936800179c9SKees Cook err = may_follow_link(&link, nd); 1937800179c9SKees Cook if (unlikely(err)) 1938800179c9SKees Cook break; 1939bd92d7feSAl Viro nd->flags |= LOOKUP_PARENT; 1940574197e0SAl Viro err = follow_link(&link, nd, &cookie); 19416d7b5aaeSAl Viro if (err) 19426d7b5aaeSAl Viro break; 1943bd92d7feSAl Viro err = lookup_last(nd, &path); 1944574197e0SAl Viro put_link(nd, &link, cookie); 1945bd92d7feSAl Viro } 1946bd92d7feSAl Viro } 1947ee0827cdSAl Viro 19489f1fafeeSAl Viro if (!err) 19499f1fafeeSAl Viro err = complete_walk(nd); 1950bd92d7feSAl Viro 1951bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 1952bd92d7feSAl Viro if (!nd->inode->i_op->lookup) { 1953bd92d7feSAl Viro path_put(&nd->path); 1954bd23a539SAl Viro err = -ENOTDIR; 1955bd92d7feSAl Viro } 1956bd92d7feSAl Viro } 195716c2cd71SAl Viro 195870e9b357SAl Viro if (base) 195970e9b357SAl Viro fput(base); 1960ee0827cdSAl Viro 19615b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 196231e6b01fSNick Piggin path_put(&nd->root); 196331e6b01fSNick Piggin nd->root.mnt = NULL; 196431e6b01fSNick Piggin } 1965bd92d7feSAl Viro return err; 196631e6b01fSNick Piggin } 196731e6b01fSNick Piggin 1968ee0827cdSAl Viro static int do_path_lookup(int dfd, const char *name, 1969ee0827cdSAl Viro unsigned int flags, struct nameidata *nd) 1970ee0827cdSAl Viro { 1971ee0827cdSAl Viro int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 1972ee0827cdSAl Viro if (unlikely(retval == -ECHILD)) 1973ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags, nd); 1974ee0827cdSAl Viro if (unlikely(retval == -ESTALE)) 1975ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 1976ee0827cdSAl Viro 197731e6b01fSNick Piggin if (likely(!retval)) { 197831e6b01fSNick Piggin if (unlikely(!audit_dummy_context())) { 197931e6b01fSNick Piggin if (nd->path.dentry && nd->inode) 198031e6b01fSNick Piggin audit_inode(name, nd->path.dentry); 198131e6b01fSNick Piggin } 198231e6b01fSNick Piggin } 1983170aa3d0SUlrich Drepper return retval; 19841da177e4SLinus Torvalds } 19851da177e4SLinus Torvalds 198679714f72SAl Viro /* does lookup, returns the object with parent locked */ 198779714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 19885590ff0dSUlrich Drepper { 198979714f72SAl Viro struct nameidata nd; 199079714f72SAl Viro struct dentry *d; 199179714f72SAl Viro int err = do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, &nd); 199279714f72SAl Viro if (err) 199379714f72SAl Viro return ERR_PTR(err); 199479714f72SAl Viro if (nd.last_type != LAST_NORM) { 199579714f72SAl Viro path_put(&nd.path); 199679714f72SAl Viro return ERR_PTR(-EINVAL); 199779714f72SAl Viro } 199879714f72SAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 19991e0ea001SAl Viro d = __lookup_hash(&nd.last, nd.path.dentry, 0); 200079714f72SAl Viro if (IS_ERR(d)) { 200179714f72SAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 200279714f72SAl Viro path_put(&nd.path); 200379714f72SAl Viro return d; 200479714f72SAl Viro } 200579714f72SAl Viro *path = nd.path; 200679714f72SAl Viro return d; 20075590ff0dSUlrich Drepper } 20085590ff0dSUlrich Drepper 2009d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2010d1811465SAl Viro { 2011d1811465SAl Viro struct nameidata nd; 2012d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 2013d1811465SAl Viro if (!res) 2014d1811465SAl Viro *path = nd.path; 2015d1811465SAl Viro return res; 2016d1811465SAl Viro } 2017d1811465SAl Viro 201816f18200SJosef 'Jeff' Sipek /** 201916f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 202016f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 202116f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 202216f18200SJosef 'Jeff' Sipek * @name: pointer to file name 202316f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2024e0a01249SAl Viro * @path: pointer to struct path to fill 202516f18200SJosef 'Jeff' Sipek */ 202616f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 202716f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2028e0a01249SAl Viro struct path *path) 202916f18200SJosef 'Jeff' Sipek { 2030e0a01249SAl Viro struct nameidata nd; 2031e0a01249SAl Viro int err; 2032e0a01249SAl Viro nd.root.dentry = dentry; 2033e0a01249SAl Viro nd.root.mnt = mnt; 2034e0a01249SAl Viro BUG_ON(flags & LOOKUP_PARENT); 20355b6ca027SAl Viro /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ 2036e0a01249SAl Viro err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd); 2037e0a01249SAl Viro if (!err) 2038e0a01249SAl Viro *path = nd.path; 2039e0a01249SAl Viro return err; 204016f18200SJosef 'Jeff' Sipek } 204116f18200SJosef 'Jeff' Sipek 2042057f6c01SJames Morris /* 2043057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 2044057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 2045057f6c01SJames Morris * SMP-safe. 2046057f6c01SJames Morris */ 2047a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 20481da177e4SLinus Torvalds { 204972bd866aSAl Viro return __lookup_hash(&nd->last, nd->path.dentry, nd->flags); 20501da177e4SLinus Torvalds } 20511da177e4SLinus Torvalds 2052eead1911SChristoph Hellwig /** 2053a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2054eead1911SChristoph Hellwig * @name: pathname component to lookup 2055eead1911SChristoph Hellwig * @base: base directory to lookup from 2056eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2057eead1911SChristoph Hellwig * 2058a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 2059a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 2060eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 2061eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 2062eead1911SChristoph Hellwig */ 2063057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2064057f6c01SJames Morris { 2065057f6c01SJames Morris struct qstr this; 20666a96ba54SAl Viro unsigned int c; 2067cda309deSMiklos Szeredi int err; 2068057f6c01SJames Morris 20692f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 20702f9092e1SDavid Woodhouse 20716a96ba54SAl Viro this.name = name; 20726a96ba54SAl Viro this.len = len; 20730145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 20746a96ba54SAl Viro if (!len) 20756a96ba54SAl Viro return ERR_PTR(-EACCES); 20766a96ba54SAl Viro 20776a96ba54SAl Viro while (len--) { 20786a96ba54SAl Viro c = *(const unsigned char *)name++; 20796a96ba54SAl Viro if (c == '/' || c == '\0') 20806a96ba54SAl Viro return ERR_PTR(-EACCES); 20816a96ba54SAl Viro } 20825a202bcdSAl Viro /* 20835a202bcdSAl Viro * See if the low-level filesystem might want 20845a202bcdSAl Viro * to use its own hash.. 20855a202bcdSAl Viro */ 20865a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 20875a202bcdSAl Viro int err = base->d_op->d_hash(base, base->d_inode, &this); 20885a202bcdSAl Viro if (err < 0) 20895a202bcdSAl Viro return ERR_PTR(err); 20905a202bcdSAl Viro } 2091eead1911SChristoph Hellwig 2092cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2093cda309deSMiklos Szeredi if (err) 2094cda309deSMiklos Szeredi return ERR_PTR(err); 2095cda309deSMiklos Szeredi 209672bd866aSAl Viro return __lookup_hash(&this, base, 0); 2097057f6c01SJames Morris } 2098057f6c01SJames Morris 20991fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 21001fa1e7f6SAndy Whitcroft struct path *path, int *empty) 21011da177e4SLinus Torvalds { 21022d8f3038SAl Viro struct nameidata nd; 21031fa1e7f6SAndy Whitcroft char *tmp = getname_flags(name, flags, empty); 21041da177e4SLinus Torvalds int err = PTR_ERR(tmp); 21051da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 21062d8f3038SAl Viro 21072d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 21082d8f3038SAl Viro 21092d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 21101da177e4SLinus Torvalds putname(tmp); 21112d8f3038SAl Viro if (!err) 21122d8f3038SAl Viro *path = nd.path; 21131da177e4SLinus Torvalds } 21141da177e4SLinus Torvalds return err; 21151da177e4SLinus Torvalds } 21161da177e4SLinus Torvalds 21171fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 21181fa1e7f6SAndy Whitcroft struct path *path) 21191fa1e7f6SAndy Whitcroft { 2120f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 21211fa1e7f6SAndy Whitcroft } 21221fa1e7f6SAndy Whitcroft 21232ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 21242ad94ae6SAl Viro struct nameidata *nd, char **name) 21252ad94ae6SAl Viro { 21262ad94ae6SAl Viro char *s = getname(path); 21272ad94ae6SAl Viro int error; 21282ad94ae6SAl Viro 21292ad94ae6SAl Viro if (IS_ERR(s)) 21302ad94ae6SAl Viro return PTR_ERR(s); 21312ad94ae6SAl Viro 21322ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 21332ad94ae6SAl Viro if (error) 21342ad94ae6SAl Viro putname(s); 21352ad94ae6SAl Viro else 21362ad94ae6SAl Viro *name = s; 21372ad94ae6SAl Viro 21382ad94ae6SAl Viro return error; 21392ad94ae6SAl Viro } 21402ad94ae6SAl Viro 21411da177e4SLinus Torvalds /* 21421da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 21431da177e4SLinus Torvalds * minimal. 21441da177e4SLinus Torvalds */ 21451da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 21461da177e4SLinus Torvalds { 21478e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2148da9592edSDavid Howells 21491da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 21501da177e4SLinus Torvalds return 0; 21518e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 21521da177e4SLinus Torvalds return 0; 21538e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 21541da177e4SLinus Torvalds return 0; 21551a48e2acSEric W. Biederman return !inode_capable(inode, CAP_FOWNER); 21561da177e4SLinus Torvalds } 21571da177e4SLinus Torvalds 21581da177e4SLinus Torvalds /* 21591da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 21601da177e4SLinus Torvalds * whether the type of victim is right. 21611da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 21621da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 21631da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 21641da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 21651da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 21661da177e4SLinus Torvalds * a. be owner of dir, or 21671da177e4SLinus Torvalds * b. be owner of victim, or 21681da177e4SLinus Torvalds * c. have CAP_FOWNER capability 21691da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 21701da177e4SLinus Torvalds * links pointing to it. 21711da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 21721da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 21731da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 21741da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 21751da177e4SLinus Torvalds * nfs_async_unlink(). 21761da177e4SLinus Torvalds */ 2177858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 21781da177e4SLinus Torvalds { 21791da177e4SLinus Torvalds int error; 21801da177e4SLinus Torvalds 21811da177e4SLinus Torvalds if (!victim->d_inode) 21821da177e4SLinus Torvalds return -ENOENT; 21831da177e4SLinus Torvalds 21841da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 2185cccc6bbaSAl Viro audit_inode_child(victim, dir); 21861da177e4SLinus Torvalds 2187f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 21881da177e4SLinus Torvalds if (error) 21891da177e4SLinus Torvalds return error; 21901da177e4SLinus Torvalds if (IS_APPEND(dir)) 21911da177e4SLinus Torvalds return -EPERM; 21921da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 2193f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 21941da177e4SLinus Torvalds return -EPERM; 21951da177e4SLinus Torvalds if (isdir) { 21961da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 21971da177e4SLinus Torvalds return -ENOTDIR; 21981da177e4SLinus Torvalds if (IS_ROOT(victim)) 21991da177e4SLinus Torvalds return -EBUSY; 22001da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 22011da177e4SLinus Torvalds return -EISDIR; 22021da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 22031da177e4SLinus Torvalds return -ENOENT; 22041da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 22051da177e4SLinus Torvalds return -EBUSY; 22061da177e4SLinus Torvalds return 0; 22071da177e4SLinus Torvalds } 22081da177e4SLinus Torvalds 22091da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 22101da177e4SLinus Torvalds * dir. 22111da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 22121da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 22131da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 22141da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 22151da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 22161da177e4SLinus Torvalds */ 2217a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 22181da177e4SLinus Torvalds { 22191da177e4SLinus Torvalds if (child->d_inode) 22201da177e4SLinus Torvalds return -EEXIST; 22211da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 22221da177e4SLinus Torvalds return -ENOENT; 2223f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 22241da177e4SLinus Torvalds } 22251da177e4SLinus Torvalds 22261da177e4SLinus Torvalds /* 22271da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 22281da177e4SLinus Torvalds */ 22291da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 22301da177e4SLinus Torvalds { 22311da177e4SLinus Torvalds struct dentry *p; 22321da177e4SLinus Torvalds 22331da177e4SLinus Torvalds if (p1 == p2) { 2234f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 22351da177e4SLinus Torvalds return NULL; 22361da177e4SLinus Torvalds } 22371da177e4SLinus Torvalds 2238a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 22391da177e4SLinus Torvalds 2240e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2241e2761a11SOGAWA Hirofumi if (p) { 2242f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2243f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 22441da177e4SLinus Torvalds return p; 22451da177e4SLinus Torvalds } 22461da177e4SLinus Torvalds 2247e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2248e2761a11SOGAWA Hirofumi if (p) { 2249f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2250f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 22511da177e4SLinus Torvalds return p; 22521da177e4SLinus Torvalds } 22531da177e4SLinus Torvalds 2254f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2255f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 22561da177e4SLinus Torvalds return NULL; 22571da177e4SLinus Torvalds } 22581da177e4SLinus Torvalds 22591da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 22601da177e4SLinus Torvalds { 22611b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 22621da177e4SLinus Torvalds if (p1 != p2) { 22631b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2264a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 22651da177e4SLinus Torvalds } 22661da177e4SLinus Torvalds } 22671da177e4SLinus Torvalds 22684acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2269312b63fbSAl Viro bool want_excl) 22701da177e4SLinus Torvalds { 2271a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 22721da177e4SLinus Torvalds if (error) 22731da177e4SLinus Torvalds return error; 22741da177e4SLinus Torvalds 2275acfa4380SAl Viro if (!dir->i_op->create) 22761da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 22771da177e4SLinus Torvalds mode &= S_IALLUGO; 22781da177e4SLinus Torvalds mode |= S_IFREG; 22791da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 22801da177e4SLinus Torvalds if (error) 22811da177e4SLinus Torvalds return error; 2282312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2283a74574aaSStephen Smalley if (!error) 2284f38aa942SAmy Griffis fsnotify_create(dir, dentry); 22851da177e4SLinus Torvalds return error; 22861da177e4SLinus Torvalds } 22871da177e4SLinus Torvalds 228873d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 22891da177e4SLinus Torvalds { 22903fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 22911da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 22921da177e4SLinus Torvalds int error; 22931da177e4SLinus Torvalds 2294bcda7652SAl Viro /* O_PATH? */ 2295bcda7652SAl Viro if (!acc_mode) 2296bcda7652SAl Viro return 0; 2297bcda7652SAl Viro 22981da177e4SLinus Torvalds if (!inode) 22991da177e4SLinus Torvalds return -ENOENT; 23001da177e4SLinus Torvalds 2301c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2302c8fe8f30SChristoph Hellwig case S_IFLNK: 23031da177e4SLinus Torvalds return -ELOOP; 2304c8fe8f30SChristoph Hellwig case S_IFDIR: 2305c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 23061da177e4SLinus Torvalds return -EISDIR; 2307c8fe8f30SChristoph Hellwig break; 2308c8fe8f30SChristoph Hellwig case S_IFBLK: 2309c8fe8f30SChristoph Hellwig case S_IFCHR: 23103fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 23111da177e4SLinus Torvalds return -EACCES; 2312c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2313c8fe8f30SChristoph Hellwig case S_IFIFO: 2314c8fe8f30SChristoph Hellwig case S_IFSOCK: 23151da177e4SLinus Torvalds flag &= ~O_TRUNC; 2316c8fe8f30SChristoph Hellwig break; 23174a3fd211SDave Hansen } 2318b41572e9SDave Hansen 23193fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2320b41572e9SDave Hansen if (error) 2321b41572e9SDave Hansen return error; 23226146f0d5SMimi Zohar 23231da177e4SLinus Torvalds /* 23241da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 23251da177e4SLinus Torvalds */ 23261da177e4SLinus Torvalds if (IS_APPEND(inode)) { 23278737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 23287715b521SAl Viro return -EPERM; 23291da177e4SLinus Torvalds if (flag & O_TRUNC) 23307715b521SAl Viro return -EPERM; 23311da177e4SLinus Torvalds } 23321da177e4SLinus Torvalds 23331da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 23342e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 23357715b521SAl Viro return -EPERM; 23361da177e4SLinus Torvalds 2337f3c7691eSJ. Bruce Fields return 0; 23387715b521SAl Viro } 23397715b521SAl Viro 2340e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 23417715b521SAl Viro { 2342e1181ee6SJeff Layton struct path *path = &filp->f_path; 23437715b521SAl Viro struct inode *inode = path->dentry->d_inode; 23447715b521SAl Viro int error = get_write_access(inode); 23451da177e4SLinus Torvalds if (error) 23467715b521SAl Viro return error; 23471da177e4SLinus Torvalds /* 23481da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 23491da177e4SLinus Torvalds */ 23501da177e4SLinus Torvalds error = locks_verify_locked(inode); 2351be6d3e56SKentaro Takeda if (!error) 2352ea0d3ab2STetsuo Handa error = security_path_truncate(path); 23531da177e4SLinus Torvalds if (!error) { 23547715b521SAl Viro error = do_truncate(path->dentry, 0, 2355d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2356e1181ee6SJeff Layton filp); 23571da177e4SLinus Torvalds } 23581da177e4SLinus Torvalds put_write_access(inode); 2359acd0c935SMimi Zohar return error; 23601da177e4SLinus Torvalds } 23611da177e4SLinus Torvalds 2362d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2363d57999e1SDave Hansen { 23648a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 23658a5e929dSAl Viro flag--; 2366d57999e1SDave Hansen return flag; 2367d57999e1SDave Hansen } 2368d57999e1SDave Hansen 2369d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2370d18e9008SMiklos Szeredi { 2371d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2372d18e9008SMiklos Szeredi if (error) 2373d18e9008SMiklos Szeredi return error; 2374d18e9008SMiklos Szeredi 2375d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2376d18e9008SMiklos Szeredi if (error) 2377d18e9008SMiklos Szeredi return error; 2378d18e9008SMiklos Szeredi 2379d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2380d18e9008SMiklos Szeredi } 2381d18e9008SMiklos Szeredi 23821acf0af9SDavid Howells /* 23831acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 23841acf0af9SDavid Howells * dentry. 23851acf0af9SDavid Howells * 23861acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 23871acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 23881acf0af9SDavid Howells * 23891acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 23901acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 23911acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 23921acf0af9SDavid Howells * 23931acf0af9SDavid Howells * Returns an error code otherwise. 23941acf0af9SDavid Howells */ 23952675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 239630d90494SAl Viro struct path *path, struct file *file, 2397015c3bbcSMiklos Szeredi const struct open_flags *op, 239864894cf8SAl Viro bool got_write, bool need_lookup, 239947237687SAl Viro int *opened) 2400d18e9008SMiklos Szeredi { 2401d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2402d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2403d18e9008SMiklos Szeredi umode_t mode; 2404d18e9008SMiklos Szeredi int error; 2405d18e9008SMiklos Szeredi int acc_mode; 2406d18e9008SMiklos Szeredi int create_error = 0; 2407d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2408d18e9008SMiklos Szeredi 2409d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2410d18e9008SMiklos Szeredi 2411d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2412d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 24132675a4ebSAl Viro error = -ENOENT; 2414d18e9008SMiklos Szeredi goto out; 2415d18e9008SMiklos Szeredi } 2416d18e9008SMiklos Szeredi 2417d18e9008SMiklos Szeredi mode = op->mode & S_IALLUGO; 2418d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2419d18e9008SMiklos Szeredi mode &= ~current_umask(); 2420d18e9008SMiklos Szeredi 2421f8310c59SAl Viro if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) { 2422d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 242347237687SAl Viro *opened |= FILE_CREATED; 2424d18e9008SMiklos Szeredi } 2425d18e9008SMiklos Szeredi 2426d18e9008SMiklos Szeredi /* 2427d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2428d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2429d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2430d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2431d18e9008SMiklos Szeredi * 2432d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2433d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2434d18e9008SMiklos Szeredi */ 243564894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 243664894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 243764894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2438d18e9008SMiklos Szeredi /* 2439d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2440d18e9008SMiklos Szeredi * back to lookup + open 2441d18e9008SMiklos Szeredi */ 2442d18e9008SMiklos Szeredi goto no_open; 2443d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2444d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 244564894cf8SAl Viro create_error = -EROFS; 2446d18e9008SMiklos Szeredi goto no_open; 2447d18e9008SMiklos Szeredi } else { 2448d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 244964894cf8SAl Viro create_error = -EROFS; 2450d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2451d18e9008SMiklos Szeredi } 2452d18e9008SMiklos Szeredi } 2453d18e9008SMiklos Szeredi 2454d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 2455d18e9008SMiklos Szeredi error = may_o_create(&nd->path, dentry, op->mode); 2456d18e9008SMiklos Szeredi if (error) { 2457d18e9008SMiklos Szeredi create_error = error; 2458d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2459d18e9008SMiklos Szeredi goto no_open; 2460d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2461d18e9008SMiklos Szeredi } 2462d18e9008SMiklos Szeredi } 2463d18e9008SMiklos Szeredi 2464d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2465d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2466d18e9008SMiklos Szeredi 246730d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 246830d90494SAl Viro file->f_path.mnt = nd->path.mnt; 246930d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 247047237687SAl Viro opened); 2471d9585277SAl Viro if (error < 0) { 2472d9585277SAl Viro if (create_error && error == -ENOENT) 2473d9585277SAl Viro error = create_error; 2474d18e9008SMiklos Szeredi goto out; 2475d18e9008SMiklos Szeredi } 2476d18e9008SMiklos Szeredi 2477d18e9008SMiklos Szeredi acc_mode = op->acc_mode; 247847237687SAl Viro if (*opened & FILE_CREATED) { 2479d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 2480d18e9008SMiklos Szeredi acc_mode = MAY_OPEN; 2481d18e9008SMiklos Szeredi } 2482d18e9008SMiklos Szeredi 2483d9585277SAl Viro if (error) { /* returned 1, that is */ 248430d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 24852675a4ebSAl Viro error = -EIO; 2486d18e9008SMiklos Szeredi goto out; 2487d18e9008SMiklos Szeredi } 248830d90494SAl Viro if (file->f_path.dentry) { 2489d18e9008SMiklos Szeredi dput(dentry); 249030d90494SAl Viro dentry = file->f_path.dentry; 2491d18e9008SMiklos Szeredi } 2492d18e9008SMiklos Szeredi goto looked_up; 2493d18e9008SMiklos Szeredi } 2494d18e9008SMiklos Szeredi 2495d18e9008SMiklos Szeredi /* 2496d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2497d18e9008SMiklos Szeredi * here. 2498d18e9008SMiklos Szeredi */ 24992675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 25002675a4ebSAl Viro if (error) 25012675a4ebSAl Viro fput(file); 2502d18e9008SMiklos Szeredi 2503d18e9008SMiklos Szeredi out: 2504d18e9008SMiklos Szeredi dput(dentry); 25052675a4ebSAl Viro return error; 2506d18e9008SMiklos Szeredi 2507d18e9008SMiklos Szeredi no_open: 2508d18e9008SMiklos Szeredi if (need_lookup) { 250972bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2510d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 25112675a4ebSAl Viro return PTR_ERR(dentry); 2512d18e9008SMiklos Szeredi 2513d18e9008SMiklos Szeredi if (create_error) { 2514d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2515d18e9008SMiklos Szeredi 25162675a4ebSAl Viro error = create_error; 2517d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2518d18e9008SMiklos Szeredi if (!dentry->d_inode) 2519d18e9008SMiklos Szeredi goto out; 2520d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2521d18e9008SMiklos Szeredi goto out; 2522d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2523d18e9008SMiklos Szeredi S_ISREG(dentry->d_inode->i_mode)) { 2524d18e9008SMiklos Szeredi goto out; 2525d18e9008SMiklos Szeredi } 2526d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2527d18e9008SMiklos Szeredi } 2528d18e9008SMiklos Szeredi } 2529d18e9008SMiklos Szeredi looked_up: 2530d18e9008SMiklos Szeredi path->dentry = dentry; 2531d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 25322675a4ebSAl Viro return 1; 2533d18e9008SMiklos Szeredi } 2534d18e9008SMiklos Szeredi 253531e6b01fSNick Piggin /* 25361acf0af9SDavid Howells * Look up and maybe create and open the last component. 2537d58ffd35SMiklos Szeredi * 2538d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2539d58ffd35SMiklos Szeredi * 25401acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 25411acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 25421acf0af9SDavid Howells * 25431acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 25441acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 25451acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 25461acf0af9SDavid Howells * specified then a negative dentry may be returned. 25471acf0af9SDavid Howells * 25481acf0af9SDavid Howells * An error code is returned otherwise. 25491acf0af9SDavid Howells * 25501acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 25511acf0af9SDavid Howells * cleared otherwise prior to returning. 2552d58ffd35SMiklos Szeredi */ 25532675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 255430d90494SAl Viro struct file *file, 2555d58ffd35SMiklos Szeredi const struct open_flags *op, 255664894cf8SAl Viro bool got_write, int *opened) 2557d58ffd35SMiklos Szeredi { 2558d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 255954ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2560d58ffd35SMiklos Szeredi struct dentry *dentry; 2561d58ffd35SMiklos Szeredi int error; 256254ef4872SMiklos Szeredi bool need_lookup; 2563d58ffd35SMiklos Szeredi 256447237687SAl Viro *opened &= ~FILE_CREATED; 2565201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2566d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 25672675a4ebSAl Viro return PTR_ERR(dentry); 2568d58ffd35SMiklos Szeredi 2569d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2570d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2571d18e9008SMiklos Szeredi goto out_no_open; 2572d18e9008SMiklos Szeredi 2573d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 257464894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 257547237687SAl Viro need_lookup, opened); 2576d18e9008SMiklos Szeredi } 2577d18e9008SMiklos Szeredi 257854ef4872SMiklos Szeredi if (need_lookup) { 257954ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 258054ef4872SMiklos Szeredi 258172bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 258254ef4872SMiklos Szeredi if (IS_ERR(dentry)) 25832675a4ebSAl Viro return PTR_ERR(dentry); 258454ef4872SMiklos Szeredi } 258554ef4872SMiklos Szeredi 2586d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2587d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2588d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2589d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2590d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2591d58ffd35SMiklos Szeredi /* 2592d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2593d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2594d58ffd35SMiklos Szeredi * the time when the file is created and when 2595d58ffd35SMiklos Szeredi * a permanent write count is taken through 2596015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 2597d58ffd35SMiklos Szeredi */ 259864894cf8SAl Viro if (!got_write) { 259964894cf8SAl Viro error = -EROFS; 2600d58ffd35SMiklos Szeredi goto out_dput; 260164894cf8SAl Viro } 260247237687SAl Viro *opened |= FILE_CREATED; 2603d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2604d58ffd35SMiklos Szeredi if (error) 2605d58ffd35SMiklos Szeredi goto out_dput; 2606312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 2607312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 2608d58ffd35SMiklos Szeredi if (error) 2609d58ffd35SMiklos Szeredi goto out_dput; 2610d58ffd35SMiklos Szeredi } 2611d18e9008SMiklos Szeredi out_no_open: 2612d58ffd35SMiklos Szeredi path->dentry = dentry; 2613d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 26142675a4ebSAl Viro return 1; 2615d58ffd35SMiklos Szeredi 2616d58ffd35SMiklos Szeredi out_dput: 2617d58ffd35SMiklos Szeredi dput(dentry); 26182675a4ebSAl Viro return error; 2619d58ffd35SMiklos Szeredi } 2620d58ffd35SMiklos Szeredi 2621d58ffd35SMiklos Szeredi /* 2622fe2d35ffSAl Viro * Handle the last step of open() 262331e6b01fSNick Piggin */ 26242675a4ebSAl Viro static int do_last(struct nameidata *nd, struct path *path, 262530d90494SAl Viro struct file *file, const struct open_flags *op, 262647237687SAl Viro int *opened, const char *pathname) 2627fb1cc555SAl Viro { 2628a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2629ca344a89SAl Viro int open_flag = op->open_flag; 263077d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 263164894cf8SAl Viro bool got_write = false; 2632bcda7652SAl Viro int acc_mode = op->acc_mode; 2633a1eb3315SMiklos Szeredi struct inode *inode; 263477d660a8SMiklos Szeredi bool symlink_ok = false; 263516b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 263616b1c1cdSMiklos Szeredi bool retried = false; 263716c2cd71SAl Viro int error; 2638fb1cc555SAl Viro 2639c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2640c3e380b0SAl Viro nd->flags |= op->intent; 2641c3e380b0SAl Viro 26421f36f774SAl Viro switch (nd->last_type) { 26431f36f774SAl Viro case LAST_DOTDOT: 2644176306f5SNeil Brown case LAST_DOT: 2645fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2646fe2d35ffSAl Viro if (error) 26472675a4ebSAl Viro return error; 26481f36f774SAl Viro /* fallthrough */ 26491f36f774SAl Viro case LAST_ROOT: 26509f1fafeeSAl Viro error = complete_walk(nd); 265116c2cd71SAl Viro if (error) 26522675a4ebSAl Viro return error; 2653fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2654ca344a89SAl Viro if (open_flag & O_CREAT) { 265516c2cd71SAl Viro error = -EISDIR; 26562675a4ebSAl Viro goto out; 2657fe2d35ffSAl Viro } 2658e83db167SMiklos Szeredi goto finish_open; 26591f36f774SAl Viro case LAST_BIND: 26609f1fafeeSAl Viro error = complete_walk(nd); 266116c2cd71SAl Viro if (error) 26622675a4ebSAl Viro return error; 26631f36f774SAl Viro audit_inode(pathname, dir); 2664e83db167SMiklos Szeredi goto finish_open; 26651f36f774SAl Viro } 2666a2c36b45SAl Viro 2667ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2668fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2669fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2670bcda7652SAl Viro if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) 267177d660a8SMiklos Szeredi symlink_ok = true; 2672fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2673a1eb3315SMiklos Szeredi error = lookup_fast(nd, &nd->last, path, &inode); 267471574865SMiklos Szeredi if (likely(!error)) 267571574865SMiklos Szeredi goto finish_lookup; 267671574865SMiklos Szeredi 2677ce57dfc1SAl Viro if (error < 0) 26782675a4ebSAl Viro goto out; 2679a1eb3315SMiklos Szeredi 268037d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 2681b6183df7SMiklos Szeredi } else { 2682fe2d35ffSAl Viro /* create side of things */ 2683a3fbbde7SAl Viro /* 2684b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 2685b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 2686b6183df7SMiklos Szeredi * about to look up 2687a3fbbde7SAl Viro */ 26889f1fafeeSAl Viro error = complete_walk(nd); 26899f1fafeeSAl Viro if (error) 26902675a4ebSAl Viro return error; 2691fe2d35ffSAl Viro 2692fe2d35ffSAl Viro audit_inode(pathname, dir); 269316c2cd71SAl Viro error = -EISDIR; 26941f36f774SAl Viro /* trailing slashes? */ 269531e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 26962675a4ebSAl Viro goto out; 2697b6183df7SMiklos Szeredi } 26981f36f774SAl Viro 269916b1c1cdSMiklos Szeredi retry_lookup: 270064894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 270164894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 270264894cf8SAl Viro if (!error) 270364894cf8SAl Viro got_write = true; 270464894cf8SAl Viro /* 270564894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 270664894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 270764894cf8SAl Viro * dropping this one anyway. 270864894cf8SAl Viro */ 270964894cf8SAl Viro } 2710a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 271164894cf8SAl Viro error = lookup_open(nd, path, file, op, got_write, opened); 2712fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2713fb1cc555SAl Viro 27142675a4ebSAl Viro if (error <= 0) { 27152675a4ebSAl Viro if (error) 2716d58ffd35SMiklos Szeredi goto out; 27176c0d46c4SAl Viro 271847237687SAl Viro if ((*opened & FILE_CREATED) || 27192675a4ebSAl Viro !S_ISREG(file->f_path.dentry->d_inode->i_mode)) 272077d660a8SMiklos Szeredi will_truncate = false; 2721d18e9008SMiklos Szeredi 27222675a4ebSAl Viro audit_inode(pathname, file->f_path.dentry); 2723d18e9008SMiklos Szeredi goto opened; 2724d18e9008SMiklos Szeredi } 2725d18e9008SMiklos Szeredi 272647237687SAl Viro if (*opened & FILE_CREATED) { 27279b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 2728ca344a89SAl Viro open_flag &= ~O_TRUNC; 272977d660a8SMiklos Szeredi will_truncate = false; 2730bcda7652SAl Viro acc_mode = MAY_OPEN; 2731d58ffd35SMiklos Szeredi path_to_nameidata(path, nd); 2732e83db167SMiklos Szeredi goto finish_open_created; 2733fb1cc555SAl Viro } 2734fb1cc555SAl Viro 2735fb1cc555SAl Viro /* 27363134f37eSJeff Layton * create/update audit record if it already exists. 2737fb1cc555SAl Viro */ 27383134f37eSJeff Layton if (path->dentry->d_inode) 2739fb1cc555SAl Viro audit_inode(pathname, path->dentry); 2740fb1cc555SAl Viro 2741d18e9008SMiklos Szeredi /* 2742d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 2743d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 2744d18e9008SMiklos Szeredi * necessary...) 2745d18e9008SMiklos Szeredi */ 274664894cf8SAl Viro if (got_write) { 2747d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 274864894cf8SAl Viro got_write = false; 2749d18e9008SMiklos Szeredi } 2750d18e9008SMiklos Szeredi 2751fb1cc555SAl Viro error = -EEXIST; 2752f8310c59SAl Viro if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) 2753fb1cc555SAl Viro goto exit_dput; 2754fb1cc555SAl Viro 27559875cf80SDavid Howells error = follow_managed(path, nd->flags); 27569875cf80SDavid Howells if (error < 0) 2757fb1cc555SAl Viro goto exit_dput; 2758fb1cc555SAl Viro 2759a3fbbde7SAl Viro if (error) 2760a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 2761a3fbbde7SAl Viro 2762decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 2763decf3400SMiklos Szeredi inode = path->dentry->d_inode; 27645f5daac1SMiklos Szeredi finish_lookup: 27655f5daac1SMiklos Szeredi /* we _can_ be in RCU mode here */ 2766fb1cc555SAl Viro error = -ENOENT; 276754c33e7fSMiklos Szeredi if (!inode) { 276854c33e7fSMiklos Szeredi path_to_nameidata(path, nd); 27692675a4ebSAl Viro goto out; 277054c33e7fSMiklos Szeredi } 27719e67f361SAl Viro 2772d45ea867SMiklos Szeredi if (should_follow_link(inode, !symlink_ok)) { 2773d45ea867SMiklos Szeredi if (nd->flags & LOOKUP_RCU) { 2774d45ea867SMiklos Szeredi if (unlikely(unlazy_walk(nd, path->dentry))) { 2775d45ea867SMiklos Szeredi error = -ECHILD; 27762675a4ebSAl Viro goto out; 2777d45ea867SMiklos Szeredi } 2778d45ea867SMiklos Szeredi } 2779d45ea867SMiklos Szeredi BUG_ON(inode != path->dentry->d_inode); 27802675a4ebSAl Viro return 1; 2781d45ea867SMiklos Szeredi } 2782fb1cc555SAl Viro 278316b1c1cdSMiklos Szeredi if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path->mnt) { 2784fb1cc555SAl Viro path_to_nameidata(path, nd); 278516b1c1cdSMiklos Szeredi } else { 278616b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 278716b1c1cdSMiklos Szeredi save_parent.mnt = mntget(path->mnt); 278816b1c1cdSMiklos Szeredi nd->path.dentry = path->dentry; 278916b1c1cdSMiklos Szeredi 279016b1c1cdSMiklos Szeredi } 2791decf3400SMiklos Szeredi nd->inode = inode; 2792a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 2793a3fbbde7SAl Viro error = complete_walk(nd); 279416b1c1cdSMiklos Szeredi if (error) { 279516b1c1cdSMiklos Szeredi path_put(&save_parent); 27962675a4ebSAl Viro return error; 279716b1c1cdSMiklos Szeredi } 2798fb1cc555SAl Viro error = -EISDIR; 2799050ac841SMiklos Szeredi if ((open_flag & O_CREAT) && S_ISDIR(nd->inode->i_mode)) 28002675a4ebSAl Viro goto out; 2801af2f5542SMiklos Szeredi error = -ENOTDIR; 2802af2f5542SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !nd->inode->i_op->lookup) 28032675a4ebSAl Viro goto out; 2804d7fdd7f6SMiklos Szeredi audit_inode(pathname, nd->path.dentry); 2805e83db167SMiklos Szeredi finish_open: 28066c0d46c4SAl Viro if (!S_ISREG(nd->inode->i_mode)) 280777d660a8SMiklos Szeredi will_truncate = false; 28086c0d46c4SAl Viro 28090f9d1a10SAl Viro if (will_truncate) { 28100f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 28110f9d1a10SAl Viro if (error) 28122675a4ebSAl Viro goto out; 281364894cf8SAl Viro got_write = true; 28140f9d1a10SAl Viro } 2815e83db167SMiklos Szeredi finish_open_created: 2816bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 2817ca344a89SAl Viro if (error) 28182675a4ebSAl Viro goto out; 281930d90494SAl Viro file->f_path.mnt = nd->path.mnt; 282030d90494SAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 282130d90494SAl Viro if (error) { 282230d90494SAl Viro if (error == -EOPENSTALE) 2823f60dc3dbSMiklos Szeredi goto stale_open; 2824015c3bbcSMiklos Szeredi goto out; 2825f60dc3dbSMiklos Szeredi } 2826a8277b9bSMiklos Szeredi opened: 28272675a4ebSAl Viro error = open_check_o_direct(file); 2828015c3bbcSMiklos Szeredi if (error) 2829015c3bbcSMiklos Szeredi goto exit_fput; 28302675a4ebSAl Viro error = ima_file_check(file, op->acc_mode); 2831aa4caadbSMiklos Szeredi if (error) 2832aa4caadbSMiklos Szeredi goto exit_fput; 2833aa4caadbSMiklos Szeredi 28340f9d1a10SAl Viro if (will_truncate) { 28352675a4ebSAl Viro error = handle_truncate(file); 2836aa4caadbSMiklos Szeredi if (error) 2837aa4caadbSMiklos Szeredi goto exit_fput; 28380f9d1a10SAl Viro } 2839ca344a89SAl Viro out: 284064894cf8SAl Viro if (got_write) 28410f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 284216b1c1cdSMiklos Szeredi path_put(&save_parent); 2843e276ae67SMiklos Szeredi terminate_walk(nd); 28442675a4ebSAl Viro return error; 2845fb1cc555SAl Viro 2846fb1cc555SAl Viro exit_dput: 2847fb1cc555SAl Viro path_put_conditional(path, nd); 2848ca344a89SAl Viro goto out; 2849015c3bbcSMiklos Szeredi exit_fput: 28502675a4ebSAl Viro fput(file); 28512675a4ebSAl Viro goto out; 2852015c3bbcSMiklos Szeredi 2853f60dc3dbSMiklos Szeredi stale_open: 2854f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 2855f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 2856f60dc3dbSMiklos Szeredi goto out; 2857f60dc3dbSMiklos Szeredi 2858f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 2859f60dc3dbSMiklos Szeredi path_put(&nd->path); 2860f60dc3dbSMiklos Szeredi nd->path = save_parent; 2861f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 2862f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 2863f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 286464894cf8SAl Viro if (got_write) { 2865f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 286664894cf8SAl Viro got_write = false; 2867f60dc3dbSMiklos Szeredi } 2868f60dc3dbSMiklos Szeredi retried = true; 2869f60dc3dbSMiklos Szeredi goto retry_lookup; 2870fb1cc555SAl Viro } 2871fb1cc555SAl Viro 287213aab428SAl Viro static struct file *path_openat(int dfd, const char *pathname, 287373d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 28741da177e4SLinus Torvalds { 2875fe2d35ffSAl Viro struct file *base = NULL; 287630d90494SAl Viro struct file *file; 28779850c056SAl Viro struct path path; 287847237687SAl Viro int opened = 0; 287913aab428SAl Viro int error; 288031e6b01fSNick Piggin 288130d90494SAl Viro file = get_empty_filp(); 288230d90494SAl Viro if (!file) 288331e6b01fSNick Piggin return ERR_PTR(-ENFILE); 288431e6b01fSNick Piggin 288530d90494SAl Viro file->f_flags = op->open_flag; 288631e6b01fSNick Piggin 288773d049a4SAl Viro error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base); 288831e6b01fSNick Piggin if (unlikely(error)) 28892675a4ebSAl Viro goto out; 289031e6b01fSNick Piggin 2891fe2d35ffSAl Viro current->total_link_count = 0; 289273d049a4SAl Viro error = link_path_walk(pathname, nd); 289331e6b01fSNick Piggin if (unlikely(error)) 28942675a4ebSAl Viro goto out; 28951da177e4SLinus Torvalds 28962675a4ebSAl Viro error = do_last(nd, &path, file, op, &opened, pathname); 28972675a4ebSAl Viro while (unlikely(error > 0)) { /* trailing symlink */ 28987b9337aaSNick Piggin struct path link = path; 2899def4af30SAl Viro void *cookie; 2900574197e0SAl Viro if (!(nd->flags & LOOKUP_FOLLOW)) { 290173d049a4SAl Viro path_put_conditional(&path, nd); 290273d049a4SAl Viro path_put(&nd->path); 29032675a4ebSAl Viro error = -ELOOP; 290440b39136SAl Viro break; 290540b39136SAl Viro } 2906800179c9SKees Cook error = may_follow_link(&link, nd); 2907800179c9SKees Cook if (unlikely(error)) 2908800179c9SKees Cook break; 290973d049a4SAl Viro nd->flags |= LOOKUP_PARENT; 291073d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 2911574197e0SAl Viro error = follow_link(&link, nd, &cookie); 2912c3e380b0SAl Viro if (unlikely(error)) 29132675a4ebSAl Viro break; 29142675a4ebSAl Viro error = do_last(nd, &path, file, op, &opened, pathname); 2915574197e0SAl Viro put_link(nd, &link, cookie); 2916806b681cSAl Viro } 291710fa8e62SAl Viro out: 291873d049a4SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) 291973d049a4SAl Viro path_put(&nd->root); 2920fe2d35ffSAl Viro if (base) 2921fe2d35ffSAl Viro fput(base); 29222675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 29232675a4ebSAl Viro BUG_ON(!error); 292430d90494SAl Viro put_filp(file); 2925015c3bbcSMiklos Szeredi } 29262675a4ebSAl Viro if (unlikely(error)) { 29272675a4ebSAl Viro if (error == -EOPENSTALE) { 29282675a4ebSAl Viro if (flags & LOOKUP_RCU) 29292675a4ebSAl Viro error = -ECHILD; 29302675a4ebSAl Viro else 29312675a4ebSAl Viro error = -ESTALE; 29322675a4ebSAl Viro } 29332675a4ebSAl Viro file = ERR_PTR(error); 29342675a4ebSAl Viro } 29352675a4ebSAl Viro return file; 2936de459215SKirill Korotaev } 29371da177e4SLinus Torvalds 293813aab428SAl Viro struct file *do_filp_open(int dfd, const char *pathname, 293913aab428SAl Viro const struct open_flags *op, int flags) 294013aab428SAl Viro { 294173d049a4SAl Viro struct nameidata nd; 294213aab428SAl Viro struct file *filp; 294313aab428SAl Viro 294473d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 294513aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 294673d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 294713aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 294873d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 294913aab428SAl Viro return filp; 295013aab428SAl Viro } 295113aab428SAl Viro 295273d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 295373d049a4SAl Viro const char *name, const struct open_flags *op, int flags) 295473d049a4SAl Viro { 295573d049a4SAl Viro struct nameidata nd; 295673d049a4SAl Viro struct file *file; 295773d049a4SAl Viro 295873d049a4SAl Viro nd.root.mnt = mnt; 295973d049a4SAl Viro nd.root.dentry = dentry; 296073d049a4SAl Viro 296173d049a4SAl Viro flags |= LOOKUP_ROOT; 296273d049a4SAl Viro 2963bcda7652SAl Viro if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) 296473d049a4SAl Viro return ERR_PTR(-ELOOP); 296573d049a4SAl Viro 296673d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU); 296773d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 296873d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags); 296973d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 297073d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL); 297173d049a4SAl Viro return file; 297273d049a4SAl Viro } 297373d049a4SAl Viro 2974ed75e95dSAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, int is_dir) 29751da177e4SLinus Torvalds { 2976c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 2977ed75e95dSAl Viro struct nameidata nd; 2978c30dabfeSJan Kara int err2; 2979ed75e95dSAl Viro int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd); 2980ed75e95dSAl Viro if (error) 2981ed75e95dSAl Viro return ERR_PTR(error); 29821da177e4SLinus Torvalds 2983c663e5d8SChristoph Hellwig /* 2984c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 2985c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 2986c663e5d8SChristoph Hellwig */ 2987ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 2988ed75e95dSAl Viro goto out; 2989ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 2990ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 2991c663e5d8SChristoph Hellwig 2992c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 2993c30dabfeSJan Kara err2 = mnt_want_write(nd.path.mnt); 2994c663e5d8SChristoph Hellwig /* 2995c663e5d8SChristoph Hellwig * Do the final lookup. 2996c663e5d8SChristoph Hellwig */ 2997ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 2998ed75e95dSAl Viro dentry = lookup_hash(&nd); 29991da177e4SLinus Torvalds if (IS_ERR(dentry)) 3000a8104a9fSAl Viro goto unlock; 3001c663e5d8SChristoph Hellwig 3002a8104a9fSAl Viro error = -EEXIST; 3003e9baf6e5SAl Viro if (dentry->d_inode) 3004a8104a9fSAl Viro goto fail; 3005c663e5d8SChristoph Hellwig /* 3006c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3007c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3008c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3009c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3010c663e5d8SChristoph Hellwig */ 3011ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 3012a8104a9fSAl Viro error = -ENOENT; 3013ed75e95dSAl Viro goto fail; 3014e9baf6e5SAl Viro } 3015c30dabfeSJan Kara if (unlikely(err2)) { 3016c30dabfeSJan Kara error = err2; 3017a8104a9fSAl Viro goto fail; 3018c30dabfeSJan Kara } 3019ed75e95dSAl Viro *path = nd.path; 3020e9baf6e5SAl Viro return dentry; 30211da177e4SLinus Torvalds fail: 3022a8104a9fSAl Viro dput(dentry); 3023a8104a9fSAl Viro dentry = ERR_PTR(error); 3024a8104a9fSAl Viro unlock: 3025dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3026c30dabfeSJan Kara if (!err2) 3027c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 3028ed75e95dSAl Viro out: 3029dae6ad8fSAl Viro path_put(&nd.path); 3030ed75e95dSAl Viro return dentry; 3031dae6ad8fSAl Viro } 3032dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3033dae6ad8fSAl Viro 3034921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3035921a1650SAl Viro { 3036921a1650SAl Viro dput(dentry); 3037921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3038a8104a9fSAl Viro mnt_drop_write(path->mnt); 3039921a1650SAl Viro path_put(path); 3040921a1650SAl Viro } 3041921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3042921a1650SAl Viro 3043dae6ad8fSAl Viro struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, int is_dir) 3044dae6ad8fSAl Viro { 3045dae6ad8fSAl Viro char *tmp = getname(pathname); 3046dae6ad8fSAl Viro struct dentry *res; 3047dae6ad8fSAl Viro if (IS_ERR(tmp)) 3048dae6ad8fSAl Viro return ERR_CAST(tmp); 3049dae6ad8fSAl Viro res = kern_path_create(dfd, tmp, path, is_dir); 3050dae6ad8fSAl Viro putname(tmp); 3051dae6ad8fSAl Viro return res; 3052dae6ad8fSAl Viro } 3053dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3054dae6ad8fSAl Viro 30551a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 30561da177e4SLinus Torvalds { 3057a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 30581da177e4SLinus Torvalds 30591da177e4SLinus Torvalds if (error) 30601da177e4SLinus Torvalds return error; 30611da177e4SLinus Torvalds 3062975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 30631da177e4SLinus Torvalds return -EPERM; 30641da177e4SLinus Torvalds 3065acfa4380SAl Viro if (!dir->i_op->mknod) 30661da177e4SLinus Torvalds return -EPERM; 30671da177e4SLinus Torvalds 306808ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 306908ce5f16SSerge E. Hallyn if (error) 307008ce5f16SSerge E. Hallyn return error; 307108ce5f16SSerge E. Hallyn 30721da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 30731da177e4SLinus Torvalds if (error) 30741da177e4SLinus Torvalds return error; 30751da177e4SLinus Torvalds 30761da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3077a74574aaSStephen Smalley if (!error) 3078f38aa942SAmy Griffis fsnotify_create(dir, dentry); 30791da177e4SLinus Torvalds return error; 30801da177e4SLinus Torvalds } 30811da177e4SLinus Torvalds 3082f69aac00SAl Viro static int may_mknod(umode_t mode) 3083463c3197SDave Hansen { 3084463c3197SDave Hansen switch (mode & S_IFMT) { 3085463c3197SDave Hansen case S_IFREG: 3086463c3197SDave Hansen case S_IFCHR: 3087463c3197SDave Hansen case S_IFBLK: 3088463c3197SDave Hansen case S_IFIFO: 3089463c3197SDave Hansen case S_IFSOCK: 3090463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3091463c3197SDave Hansen return 0; 3092463c3197SDave Hansen case S_IFDIR: 3093463c3197SDave Hansen return -EPERM; 3094463c3197SDave Hansen default: 3095463c3197SDave Hansen return -EINVAL; 3096463c3197SDave Hansen } 3097463c3197SDave Hansen } 3098463c3197SDave Hansen 30998208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 31002e4d0924SHeiko Carstens unsigned, dev) 31011da177e4SLinus Torvalds { 31021da177e4SLinus Torvalds struct dentry *dentry; 3103dae6ad8fSAl Viro struct path path; 3104dae6ad8fSAl Viro int error; 31051da177e4SLinus Torvalds 31068e4bfca1SAl Viro error = may_mknod(mode); 31078e4bfca1SAl Viro if (error) 31088e4bfca1SAl Viro return error; 31091da177e4SLinus Torvalds 3110dae6ad8fSAl Viro dentry = user_path_create(dfd, filename, &path, 0); 3111dae6ad8fSAl Viro if (IS_ERR(dentry)) 3112dae6ad8fSAl Viro return PTR_ERR(dentry); 31132ad94ae6SAl Viro 3114dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3115ce3b0f8dSAl Viro mode &= ~current_umask(); 3116dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3117be6d3e56SKentaro Takeda if (error) 3118a8104a9fSAl Viro goto out; 31191da177e4SLinus Torvalds switch (mode & S_IFMT) { 31201da177e4SLinus Torvalds case 0: case S_IFREG: 3121312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 31221da177e4SLinus Torvalds break; 31231da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3124dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 31251da177e4SLinus Torvalds new_decode_dev(dev)); 31261da177e4SLinus Torvalds break; 31271da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3128dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 31291da177e4SLinus Torvalds break; 31301da177e4SLinus Torvalds } 3131a8104a9fSAl Viro out: 3132921a1650SAl Viro done_path_create(&path, dentry); 31331da177e4SLinus Torvalds return error; 31341da177e4SLinus Torvalds } 31351da177e4SLinus Torvalds 31368208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 31375590ff0dSUlrich Drepper { 31385590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 31395590ff0dSUlrich Drepper } 31405590ff0dSUlrich Drepper 314118bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 31421da177e4SLinus Torvalds { 3143a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 31448de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 31451da177e4SLinus Torvalds 31461da177e4SLinus Torvalds if (error) 31471da177e4SLinus Torvalds return error; 31481da177e4SLinus Torvalds 3149acfa4380SAl Viro if (!dir->i_op->mkdir) 31501da177e4SLinus Torvalds return -EPERM; 31511da177e4SLinus Torvalds 31521da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 31531da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 31541da177e4SLinus Torvalds if (error) 31551da177e4SLinus Torvalds return error; 31561da177e4SLinus Torvalds 31578de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 31588de52778SAl Viro return -EMLINK; 31598de52778SAl Viro 31601da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3161a74574aaSStephen Smalley if (!error) 3162f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 31631da177e4SLinus Torvalds return error; 31641da177e4SLinus Torvalds } 31651da177e4SLinus Torvalds 3166a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 31671da177e4SLinus Torvalds { 31686902d925SDave Hansen struct dentry *dentry; 3169dae6ad8fSAl Viro struct path path; 3170dae6ad8fSAl Viro int error; 31711da177e4SLinus Torvalds 3172dae6ad8fSAl Viro dentry = user_path_create(dfd, pathname, &path, 1); 31736902d925SDave Hansen if (IS_ERR(dentry)) 3174dae6ad8fSAl Viro return PTR_ERR(dentry); 31756902d925SDave Hansen 3176dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3177ce3b0f8dSAl Viro mode &= ~current_umask(); 3178dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3179a8104a9fSAl Viro if (!error) 3180dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3181921a1650SAl Viro done_path_create(&path, dentry); 31821da177e4SLinus Torvalds return error; 31831da177e4SLinus Torvalds } 31841da177e4SLinus Torvalds 3185a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 31865590ff0dSUlrich Drepper { 31875590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 31885590ff0dSUlrich Drepper } 31895590ff0dSUlrich Drepper 31901da177e4SLinus Torvalds /* 3191a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3192c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3193a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3194a71905f0SSage Weil * then we drop the dentry now. 31951da177e4SLinus Torvalds * 31961da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 31971da177e4SLinus Torvalds * do a 31981da177e4SLinus Torvalds * 31991da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 32001da177e4SLinus Torvalds * return -EBUSY; 32011da177e4SLinus Torvalds * 32021da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 32031da177e4SLinus Torvalds * that is still in use by something else.. 32041da177e4SLinus Torvalds */ 32051da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 32061da177e4SLinus Torvalds { 32071da177e4SLinus Torvalds shrink_dcache_parent(dentry); 32081da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 320964252c75SSage Weil if (dentry->d_count == 1) 32101da177e4SLinus Torvalds __d_drop(dentry); 32111da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 32121da177e4SLinus Torvalds } 32131da177e4SLinus Torvalds 32141da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 32151da177e4SLinus Torvalds { 32161da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 32171da177e4SLinus Torvalds 32181da177e4SLinus Torvalds if (error) 32191da177e4SLinus Torvalds return error; 32201da177e4SLinus Torvalds 3221acfa4380SAl Viro if (!dir->i_op->rmdir) 32221da177e4SLinus Torvalds return -EPERM; 32231da177e4SLinus Torvalds 32241d2ef590SAl Viro dget(dentry); 32251b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3226912dbc15SSage Weil 32271da177e4SLinus Torvalds error = -EBUSY; 3228912dbc15SSage Weil if (d_mountpoint(dentry)) 3229912dbc15SSage Weil goto out; 3230912dbc15SSage Weil 32311da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3232912dbc15SSage Weil if (error) 3233912dbc15SSage Weil goto out; 3234912dbc15SSage Weil 32353cebde24SSage Weil shrink_dcache_parent(dentry); 32361da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3237912dbc15SSage Weil if (error) 3238912dbc15SSage Weil goto out; 3239912dbc15SSage Weil 32401da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3241d83c49f3SAl Viro dont_mount(dentry); 32421da177e4SLinus Torvalds 3243912dbc15SSage Weil out: 3244912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 32451d2ef590SAl Viro dput(dentry); 3246912dbc15SSage Weil if (!error) 3247912dbc15SSage Weil d_delete(dentry); 32481da177e4SLinus Torvalds return error; 32491da177e4SLinus Torvalds } 32501da177e4SLinus Torvalds 32515590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 32521da177e4SLinus Torvalds { 32531da177e4SLinus Torvalds int error = 0; 32541da177e4SLinus Torvalds char * name; 32551da177e4SLinus Torvalds struct dentry *dentry; 32561da177e4SLinus Torvalds struct nameidata nd; 32571da177e4SLinus Torvalds 32582ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 32591da177e4SLinus Torvalds if (error) 32602ad94ae6SAl Viro return error; 32611da177e4SLinus Torvalds 32621da177e4SLinus Torvalds switch(nd.last_type) { 32631da177e4SLinus Torvalds case LAST_DOTDOT: 32641da177e4SLinus Torvalds error = -ENOTEMPTY; 32651da177e4SLinus Torvalds goto exit1; 32661da177e4SLinus Torvalds case LAST_DOT: 32671da177e4SLinus Torvalds error = -EINVAL; 32681da177e4SLinus Torvalds goto exit1; 32691da177e4SLinus Torvalds case LAST_ROOT: 32701da177e4SLinus Torvalds error = -EBUSY; 32711da177e4SLinus Torvalds goto exit1; 32721da177e4SLinus Torvalds } 32730612d9fbSOGAWA Hirofumi 32740612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 3275c30dabfeSJan Kara error = mnt_want_write(nd.path.mnt); 3276c30dabfeSJan Kara if (error) 3277c30dabfeSJan Kara goto exit1; 32780612d9fbSOGAWA Hirofumi 32794ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 328049705b77SChristoph Hellwig dentry = lookup_hash(&nd); 32811da177e4SLinus Torvalds error = PTR_ERR(dentry); 32826902d925SDave Hansen if (IS_ERR(dentry)) 32836902d925SDave Hansen goto exit2; 3284e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3285e6bc45d6STheodore Ts'o error = -ENOENT; 3286e6bc45d6STheodore Ts'o goto exit3; 3287e6bc45d6STheodore Ts'o } 3288be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 3289be6d3e56SKentaro Takeda if (error) 3290c30dabfeSJan Kara goto exit3; 32914ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 32920622753bSDave Hansen exit3: 32931da177e4SLinus Torvalds dput(dentry); 32946902d925SDave Hansen exit2: 32954ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3296c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 32971da177e4SLinus Torvalds exit1: 32981d957f9bSJan Blunck path_put(&nd.path); 32991da177e4SLinus Torvalds putname(name); 33001da177e4SLinus Torvalds return error; 33011da177e4SLinus Torvalds } 33021da177e4SLinus Torvalds 33033cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 33045590ff0dSUlrich Drepper { 33055590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 33065590ff0dSUlrich Drepper } 33075590ff0dSUlrich Drepper 33081da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 33091da177e4SLinus Torvalds { 33101da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 33111da177e4SLinus Torvalds 33121da177e4SLinus Torvalds if (error) 33131da177e4SLinus Torvalds return error; 33141da177e4SLinus Torvalds 3315acfa4380SAl Viro if (!dir->i_op->unlink) 33161da177e4SLinus Torvalds return -EPERM; 33171da177e4SLinus Torvalds 33181b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 33191da177e4SLinus Torvalds if (d_mountpoint(dentry)) 33201da177e4SLinus Torvalds error = -EBUSY; 33211da177e4SLinus Torvalds else { 33221da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3323bec1052eSAl Viro if (!error) { 33241da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 3325bec1052eSAl Viro if (!error) 3326d83c49f3SAl Viro dont_mount(dentry); 3327bec1052eSAl Viro } 33281da177e4SLinus Torvalds } 33291b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 33301da177e4SLinus Torvalds 33311da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 33321da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 3333ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 33341da177e4SLinus Torvalds d_delete(dentry); 33351da177e4SLinus Torvalds } 33360eeca283SRobert Love 33371da177e4SLinus Torvalds return error; 33381da177e4SLinus Torvalds } 33391da177e4SLinus Torvalds 33401da177e4SLinus Torvalds /* 33411da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 33421b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 33431da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 33441da177e4SLinus Torvalds * while waiting on the I/O. 33451da177e4SLinus Torvalds */ 33465590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 33471da177e4SLinus Torvalds { 33482ad94ae6SAl Viro int error; 33491da177e4SLinus Torvalds char *name; 33501da177e4SLinus Torvalds struct dentry *dentry; 33511da177e4SLinus Torvalds struct nameidata nd; 33521da177e4SLinus Torvalds struct inode *inode = NULL; 33531da177e4SLinus Torvalds 33542ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 33551da177e4SLinus Torvalds if (error) 33562ad94ae6SAl Viro return error; 33572ad94ae6SAl Viro 33581da177e4SLinus Torvalds error = -EISDIR; 33591da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 33601da177e4SLinus Torvalds goto exit1; 33610612d9fbSOGAWA Hirofumi 33620612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 3363c30dabfeSJan Kara error = mnt_want_write(nd.path.mnt); 3364c30dabfeSJan Kara if (error) 3365c30dabfeSJan Kara goto exit1; 33660612d9fbSOGAWA Hirofumi 33674ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 336849705b77SChristoph Hellwig dentry = lookup_hash(&nd); 33691da177e4SLinus Torvalds error = PTR_ERR(dentry); 33701da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 33711da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 337250338b88STörök Edwin if (nd.last.name[nd.last.len]) 337350338b88STörök Edwin goto slashes; 33741da177e4SLinus Torvalds inode = dentry->d_inode; 337550338b88STörök Edwin if (!inode) 3376e6bc45d6STheodore Ts'o goto slashes; 33777de9c6eeSAl Viro ihold(inode); 3378be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 3379be6d3e56SKentaro Takeda if (error) 3380c30dabfeSJan Kara goto exit2; 33814ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 33821da177e4SLinus Torvalds exit2: 33831da177e4SLinus Torvalds dput(dentry); 33841da177e4SLinus Torvalds } 33854ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 33861da177e4SLinus Torvalds if (inode) 33871da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3388c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 33891da177e4SLinus Torvalds exit1: 33901d957f9bSJan Blunck path_put(&nd.path); 33911da177e4SLinus Torvalds putname(name); 33921da177e4SLinus Torvalds return error; 33931da177e4SLinus Torvalds 33941da177e4SLinus Torvalds slashes: 33951da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 33961da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 33971da177e4SLinus Torvalds goto exit2; 33981da177e4SLinus Torvalds } 33991da177e4SLinus Torvalds 34002e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 34015590ff0dSUlrich Drepper { 34025590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 34035590ff0dSUlrich Drepper return -EINVAL; 34045590ff0dSUlrich Drepper 34055590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 34065590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 34075590ff0dSUlrich Drepper 34085590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 34095590ff0dSUlrich Drepper } 34105590ff0dSUlrich Drepper 34113480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 34125590ff0dSUlrich Drepper { 34135590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 34145590ff0dSUlrich Drepper } 34155590ff0dSUlrich Drepper 3416db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 34171da177e4SLinus Torvalds { 3418a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 34191da177e4SLinus Torvalds 34201da177e4SLinus Torvalds if (error) 34211da177e4SLinus Torvalds return error; 34221da177e4SLinus Torvalds 3423acfa4380SAl Viro if (!dir->i_op->symlink) 34241da177e4SLinus Torvalds return -EPERM; 34251da177e4SLinus Torvalds 34261da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 34271da177e4SLinus Torvalds if (error) 34281da177e4SLinus Torvalds return error; 34291da177e4SLinus Torvalds 34301da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3431a74574aaSStephen Smalley if (!error) 3432f38aa942SAmy Griffis fsnotify_create(dir, dentry); 34331da177e4SLinus Torvalds return error; 34341da177e4SLinus Torvalds } 34351da177e4SLinus Torvalds 34362e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 34372e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 34381da177e4SLinus Torvalds { 34392ad94ae6SAl Viro int error; 34401da177e4SLinus Torvalds char *from; 34416902d925SDave Hansen struct dentry *dentry; 3442dae6ad8fSAl Viro struct path path; 34431da177e4SLinus Torvalds 34441da177e4SLinus Torvalds from = getname(oldname); 34451da177e4SLinus Torvalds if (IS_ERR(from)) 34461da177e4SLinus Torvalds return PTR_ERR(from); 34472ad94ae6SAl Viro 3448dae6ad8fSAl Viro dentry = user_path_create(newdfd, newname, &path, 0); 34491da177e4SLinus Torvalds error = PTR_ERR(dentry); 34506902d925SDave Hansen if (IS_ERR(dentry)) 3451dae6ad8fSAl Viro goto out_putname; 34526902d925SDave Hansen 3453dae6ad8fSAl Viro error = security_path_symlink(&path, dentry, from); 3454a8104a9fSAl Viro if (!error) 3455dae6ad8fSAl Viro error = vfs_symlink(path.dentry->d_inode, dentry, from); 3456921a1650SAl Viro done_path_create(&path, dentry); 34576902d925SDave Hansen out_putname: 34581da177e4SLinus Torvalds putname(from); 34591da177e4SLinus Torvalds return error; 34601da177e4SLinus Torvalds } 34611da177e4SLinus Torvalds 34623480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 34635590ff0dSUlrich Drepper { 34645590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 34655590ff0dSUlrich Drepper } 34665590ff0dSUlrich Drepper 34671da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 34681da177e4SLinus Torvalds { 34691da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 34708de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 34711da177e4SLinus Torvalds int error; 34721da177e4SLinus Torvalds 34731da177e4SLinus Torvalds if (!inode) 34741da177e4SLinus Torvalds return -ENOENT; 34751da177e4SLinus Torvalds 3476a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 34771da177e4SLinus Torvalds if (error) 34781da177e4SLinus Torvalds return error; 34791da177e4SLinus Torvalds 34801da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 34811da177e4SLinus Torvalds return -EXDEV; 34821da177e4SLinus Torvalds 34831da177e4SLinus Torvalds /* 34841da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 34851da177e4SLinus Torvalds */ 34861da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 34871da177e4SLinus Torvalds return -EPERM; 3488acfa4380SAl Viro if (!dir->i_op->link) 34891da177e4SLinus Torvalds return -EPERM; 34907e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 34911da177e4SLinus Torvalds return -EPERM; 34921da177e4SLinus Torvalds 34931da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 34941da177e4SLinus Torvalds if (error) 34951da177e4SLinus Torvalds return error; 34961da177e4SLinus Torvalds 34977e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 3498aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 3499aae8a97dSAneesh Kumar K.V if (inode->i_nlink == 0) 3500aae8a97dSAneesh Kumar K.V error = -ENOENT; 35018de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 35028de52778SAl Viro error = -EMLINK; 3503aae8a97dSAneesh Kumar K.V else 35041da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 35057e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 3506e31e14ecSStephen Smalley if (!error) 35077e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 35081da177e4SLinus Torvalds return error; 35091da177e4SLinus Torvalds } 35101da177e4SLinus Torvalds 35111da177e4SLinus Torvalds /* 35121da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 35131da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 35141da177e4SLinus Torvalds * newname. --KAB 35151da177e4SLinus Torvalds * 35161da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 35171da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 35181da177e4SLinus Torvalds * and other special files. --ADM 35191da177e4SLinus Torvalds */ 35202e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 35212e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 35221da177e4SLinus Torvalds { 35231da177e4SLinus Torvalds struct dentry *new_dentry; 3524dae6ad8fSAl Viro struct path old_path, new_path; 352511a7b371SAneesh Kumar K.V int how = 0; 35261da177e4SLinus Torvalds int error; 35271da177e4SLinus Torvalds 352811a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 3529c04030e1SUlrich Drepper return -EINVAL; 353011a7b371SAneesh Kumar K.V /* 353111a7b371SAneesh Kumar K.V * To use null names we require CAP_DAC_READ_SEARCH 353211a7b371SAneesh Kumar K.V * This ensures that not everyone will be able to create 353311a7b371SAneesh Kumar K.V * handlink using the passed filedescriptor. 353411a7b371SAneesh Kumar K.V */ 353511a7b371SAneesh Kumar K.V if (flags & AT_EMPTY_PATH) { 353611a7b371SAneesh Kumar K.V if (!capable(CAP_DAC_READ_SEARCH)) 353711a7b371SAneesh Kumar K.V return -ENOENT; 353811a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 353911a7b371SAneesh Kumar K.V } 3540c04030e1SUlrich Drepper 354111a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 354211a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 354311a7b371SAneesh Kumar K.V 354411a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 35451da177e4SLinus Torvalds if (error) 35462ad94ae6SAl Viro return error; 35472ad94ae6SAl Viro 3548dae6ad8fSAl Viro new_dentry = user_path_create(newdfd, newname, &new_path, 0); 35491da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 35506902d925SDave Hansen if (IS_ERR(new_dentry)) 3551dae6ad8fSAl Viro goto out; 3552dae6ad8fSAl Viro 3553dae6ad8fSAl Viro error = -EXDEV; 3554dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 3555dae6ad8fSAl Viro goto out_dput; 3556800179c9SKees Cook error = may_linkat(&old_path); 3557800179c9SKees Cook if (unlikely(error)) 3558800179c9SKees Cook goto out_dput; 3559dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 3560be6d3e56SKentaro Takeda if (error) 3561a8104a9fSAl Viro goto out_dput; 3562dae6ad8fSAl Viro error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry); 356375c3f29dSDave Hansen out_dput: 3564921a1650SAl Viro done_path_create(&new_path, new_dentry); 35651da177e4SLinus Torvalds out: 35662d8f3038SAl Viro path_put(&old_path); 35671da177e4SLinus Torvalds 35681da177e4SLinus Torvalds return error; 35691da177e4SLinus Torvalds } 35701da177e4SLinus Torvalds 35713480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 35725590ff0dSUlrich Drepper { 3573c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 35745590ff0dSUlrich Drepper } 35755590ff0dSUlrich Drepper 35761da177e4SLinus Torvalds /* 35771da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 35781da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 35791da177e4SLinus Torvalds * Problems: 35801da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 35811da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 35821da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 3583a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 35841da177e4SLinus Torvalds * story. 35851da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 35861b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 35871da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 35881da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 3589a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 35901da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 35911da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 35921da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 3593a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 35941da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 35951da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 35961da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 3597e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 35981b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 35991da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 3600c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 36011da177e4SLinus Torvalds * locking]. 36021da177e4SLinus Torvalds */ 360375c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 36041da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 36051da177e4SLinus Torvalds { 36061da177e4SLinus Torvalds int error = 0; 36079055cba7SSage Weil struct inode *target = new_dentry->d_inode; 36088de52778SAl Viro unsigned max_links = new_dir->i_sb->s_max_links; 36091da177e4SLinus Torvalds 36101da177e4SLinus Torvalds /* 36111da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 36121da177e4SLinus Torvalds * we'll need to flip '..'. 36131da177e4SLinus Torvalds */ 36141da177e4SLinus Torvalds if (new_dir != old_dir) { 3615f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 36161da177e4SLinus Torvalds if (error) 36171da177e4SLinus Torvalds return error; 36181da177e4SLinus Torvalds } 36191da177e4SLinus Torvalds 36201da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 36211da177e4SLinus Torvalds if (error) 36221da177e4SLinus Torvalds return error; 36231da177e4SLinus Torvalds 36241d2ef590SAl Viro dget(new_dentry); 3625d83c49f3SAl Viro if (target) 36261b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 36279055cba7SSage Weil 36281da177e4SLinus Torvalds error = -EBUSY; 36299055cba7SSage Weil if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) 36309055cba7SSage Weil goto out; 36319055cba7SSage Weil 36328de52778SAl Viro error = -EMLINK; 36338de52778SAl Viro if (max_links && !target && new_dir != old_dir && 36348de52778SAl Viro new_dir->i_nlink >= max_links) 36358de52778SAl Viro goto out; 36368de52778SAl Viro 36373cebde24SSage Weil if (target) 36383cebde24SSage Weil shrink_dcache_parent(new_dentry); 36391da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 36409055cba7SSage Weil if (error) 36419055cba7SSage Weil goto out; 36429055cba7SSage Weil 36431da177e4SLinus Torvalds if (target) { 36441da177e4SLinus Torvalds target->i_flags |= S_DEAD; 3645d83c49f3SAl Viro dont_mount(new_dentry); 3646d83c49f3SAl Viro } 36479055cba7SSage Weil out: 36489055cba7SSage Weil if (target) 36491b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 36501d2ef590SAl Viro dput(new_dentry); 3651e31e14ecSStephen Smalley if (!error) 3652349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 36531da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 36541da177e4SLinus Torvalds return error; 36551da177e4SLinus Torvalds } 36561da177e4SLinus Torvalds 365775c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 36581da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 36591da177e4SLinus Torvalds { 366051892bbbSSage Weil struct inode *target = new_dentry->d_inode; 36611da177e4SLinus Torvalds int error; 36621da177e4SLinus Torvalds 36631da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 36641da177e4SLinus Torvalds if (error) 36651da177e4SLinus Torvalds return error; 36661da177e4SLinus Torvalds 36671da177e4SLinus Torvalds dget(new_dentry); 36681da177e4SLinus Torvalds if (target) 36691b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 367051892bbbSSage Weil 36711da177e4SLinus Torvalds error = -EBUSY; 367251892bbbSSage Weil if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 367351892bbbSSage Weil goto out; 367451892bbbSSage Weil 36751da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 367651892bbbSSage Weil if (error) 367751892bbbSSage Weil goto out; 367851892bbbSSage Weil 3679bec1052eSAl Viro if (target) 3680d83c49f3SAl Viro dont_mount(new_dentry); 3681349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 36821da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 368351892bbbSSage Weil out: 36841da177e4SLinus Torvalds if (target) 36851b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 36861da177e4SLinus Torvalds dput(new_dentry); 36871da177e4SLinus Torvalds return error; 36881da177e4SLinus Torvalds } 36891da177e4SLinus Torvalds 36901da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 36911da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 36921da177e4SLinus Torvalds { 36931da177e4SLinus Torvalds int error; 36941da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 369559b0df21SEric Paris const unsigned char *old_name; 36961da177e4SLinus Torvalds 36971da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 36981da177e4SLinus Torvalds return 0; 36991da177e4SLinus Torvalds 37001da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 37011da177e4SLinus Torvalds if (error) 37021da177e4SLinus Torvalds return error; 37031da177e4SLinus Torvalds 37041da177e4SLinus Torvalds if (!new_dentry->d_inode) 3705a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 37061da177e4SLinus Torvalds else 37071da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 37081da177e4SLinus Torvalds if (error) 37091da177e4SLinus Torvalds return error; 37101da177e4SLinus Torvalds 3711acfa4380SAl Viro if (!old_dir->i_op->rename) 37121da177e4SLinus Torvalds return -EPERM; 37131da177e4SLinus Torvalds 37140eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 37150eeca283SRobert Love 37161da177e4SLinus Torvalds if (is_dir) 37171da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 37181da177e4SLinus Torvalds else 37191da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 3720123df294SAl Viro if (!error) 3721123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 37225a190ae6SAl Viro new_dentry->d_inode, old_dentry); 37230eeca283SRobert Love fsnotify_oldname_free(old_name); 37240eeca283SRobert Love 37251da177e4SLinus Torvalds return error; 37261da177e4SLinus Torvalds } 37271da177e4SLinus Torvalds 37282e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 37292e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 37301da177e4SLinus Torvalds { 37311da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 37321da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 37331da177e4SLinus Torvalds struct dentry *trap; 37341da177e4SLinus Torvalds struct nameidata oldnd, newnd; 37352ad94ae6SAl Viro char *from; 37362ad94ae6SAl Viro char *to; 37372ad94ae6SAl Viro int error; 37381da177e4SLinus Torvalds 37392ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 37401da177e4SLinus Torvalds if (error) 37411da177e4SLinus Torvalds goto exit; 37421da177e4SLinus Torvalds 37432ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 37441da177e4SLinus Torvalds if (error) 37451da177e4SLinus Torvalds goto exit1; 37461da177e4SLinus Torvalds 37471da177e4SLinus Torvalds error = -EXDEV; 37484ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 37491da177e4SLinus Torvalds goto exit2; 37501da177e4SLinus Torvalds 37514ac91378SJan Blunck old_dir = oldnd.path.dentry; 37521da177e4SLinus Torvalds error = -EBUSY; 37531da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 37541da177e4SLinus Torvalds goto exit2; 37551da177e4SLinus Torvalds 37564ac91378SJan Blunck new_dir = newnd.path.dentry; 37571da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 37581da177e4SLinus Torvalds goto exit2; 37591da177e4SLinus Torvalds 3760c30dabfeSJan Kara error = mnt_want_write(oldnd.path.mnt); 3761c30dabfeSJan Kara if (error) 3762c30dabfeSJan Kara goto exit2; 3763c30dabfeSJan Kara 37640612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 37650612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 37664e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 37670612d9fbSOGAWA Hirofumi 37681da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 37691da177e4SLinus Torvalds 377049705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 37711da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 37721da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 37731da177e4SLinus Torvalds goto exit3; 37741da177e4SLinus Torvalds /* source must exist */ 37751da177e4SLinus Torvalds error = -ENOENT; 37761da177e4SLinus Torvalds if (!old_dentry->d_inode) 37771da177e4SLinus Torvalds goto exit4; 37781da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 37791da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 37801da177e4SLinus Torvalds error = -ENOTDIR; 37811da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 37821da177e4SLinus Torvalds goto exit4; 37831da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 37841da177e4SLinus Torvalds goto exit4; 37851da177e4SLinus Torvalds } 37861da177e4SLinus Torvalds /* source should not be ancestor of target */ 37871da177e4SLinus Torvalds error = -EINVAL; 37881da177e4SLinus Torvalds if (old_dentry == trap) 37891da177e4SLinus Torvalds goto exit4; 379049705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 37911da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 37921da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 37931da177e4SLinus Torvalds goto exit4; 37941da177e4SLinus Torvalds /* target should not be an ancestor of source */ 37951da177e4SLinus Torvalds error = -ENOTEMPTY; 37961da177e4SLinus Torvalds if (new_dentry == trap) 37971da177e4SLinus Torvalds goto exit5; 37981da177e4SLinus Torvalds 3799be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 3800be6d3e56SKentaro Takeda &newnd.path, new_dentry); 3801be6d3e56SKentaro Takeda if (error) 3802c30dabfeSJan Kara goto exit5; 38031da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 38041da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 38051da177e4SLinus Torvalds exit5: 38061da177e4SLinus Torvalds dput(new_dentry); 38071da177e4SLinus Torvalds exit4: 38081da177e4SLinus Torvalds dput(old_dentry); 38091da177e4SLinus Torvalds exit3: 38101da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 3811c30dabfeSJan Kara mnt_drop_write(oldnd.path.mnt); 38121da177e4SLinus Torvalds exit2: 38131d957f9bSJan Blunck path_put(&newnd.path); 38142ad94ae6SAl Viro putname(to); 38151da177e4SLinus Torvalds exit1: 38161d957f9bSJan Blunck path_put(&oldnd.path); 38171da177e4SLinus Torvalds putname(from); 38182ad94ae6SAl Viro exit: 38191da177e4SLinus Torvalds return error; 38201da177e4SLinus Torvalds } 38211da177e4SLinus Torvalds 3822a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 38235590ff0dSUlrich Drepper { 38245590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 38255590ff0dSUlrich Drepper } 38265590ff0dSUlrich Drepper 38271da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 38281da177e4SLinus Torvalds { 38291da177e4SLinus Torvalds int len; 38301da177e4SLinus Torvalds 38311da177e4SLinus Torvalds len = PTR_ERR(link); 38321da177e4SLinus Torvalds if (IS_ERR(link)) 38331da177e4SLinus Torvalds goto out; 38341da177e4SLinus Torvalds 38351da177e4SLinus Torvalds len = strlen(link); 38361da177e4SLinus Torvalds if (len > (unsigned) buflen) 38371da177e4SLinus Torvalds len = buflen; 38381da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 38391da177e4SLinus Torvalds len = -EFAULT; 38401da177e4SLinus Torvalds out: 38411da177e4SLinus Torvalds return len; 38421da177e4SLinus Torvalds } 38431da177e4SLinus Torvalds 38441da177e4SLinus Torvalds /* 38451da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 38461da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 38471da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 38481da177e4SLinus Torvalds */ 38491da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 38501da177e4SLinus Torvalds { 38511da177e4SLinus Torvalds struct nameidata nd; 3852cc314eefSLinus Torvalds void *cookie; 3853694a1764SMarcin Slusarz int res; 3854cc314eefSLinus Torvalds 38551da177e4SLinus Torvalds nd.depth = 0; 3856cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 3857694a1764SMarcin Slusarz if (IS_ERR(cookie)) 3858694a1764SMarcin Slusarz return PTR_ERR(cookie); 3859694a1764SMarcin Slusarz 3860694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 38611da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 3862cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 3863694a1764SMarcin Slusarz return res; 38641da177e4SLinus Torvalds } 38651da177e4SLinus Torvalds 38661da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 38671da177e4SLinus Torvalds { 38681da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 38691da177e4SLinus Torvalds } 38701da177e4SLinus Torvalds 38711da177e4SLinus Torvalds /* get the link contents into pagecache */ 38721da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 38731da177e4SLinus Torvalds { 3874ebd09abbSDuane Griffin char *kaddr; 38751da177e4SLinus Torvalds struct page *page; 38761da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 3877090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 38781da177e4SLinus Torvalds if (IS_ERR(page)) 38796fe6900eSNick Piggin return (char*)page; 38801da177e4SLinus Torvalds *ppage = page; 3881ebd09abbSDuane Griffin kaddr = kmap(page); 3882ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 3883ebd09abbSDuane Griffin return kaddr; 38841da177e4SLinus Torvalds } 38851da177e4SLinus Torvalds 38861da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 38871da177e4SLinus Torvalds { 38881da177e4SLinus Torvalds struct page *page = NULL; 38891da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 38901da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 38911da177e4SLinus Torvalds if (page) { 38921da177e4SLinus Torvalds kunmap(page); 38931da177e4SLinus Torvalds page_cache_release(page); 38941da177e4SLinus Torvalds } 38951da177e4SLinus Torvalds return res; 38961da177e4SLinus Torvalds } 38971da177e4SLinus Torvalds 3898cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 38991da177e4SLinus Torvalds { 3900cc314eefSLinus Torvalds struct page *page = NULL; 39011da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 3902cc314eefSLinus Torvalds return page; 39031da177e4SLinus Torvalds } 39041da177e4SLinus Torvalds 3905cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 39061da177e4SLinus Torvalds { 3907cc314eefSLinus Torvalds struct page *page = cookie; 3908cc314eefSLinus Torvalds 3909cc314eefSLinus Torvalds if (page) { 39101da177e4SLinus Torvalds kunmap(page); 39111da177e4SLinus Torvalds page_cache_release(page); 39121da177e4SLinus Torvalds } 39131da177e4SLinus Torvalds } 39141da177e4SLinus Torvalds 391554566b2cSNick Piggin /* 391654566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 391754566b2cSNick Piggin */ 391854566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 39191da177e4SLinus Torvalds { 39201da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 39210adb25d2SKirill Korotaev struct page *page; 3922afddba49SNick Piggin void *fsdata; 3923beb497abSDmitriy Monakhov int err; 39241da177e4SLinus Torvalds char *kaddr; 392554566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 392654566b2cSNick Piggin if (nofs) 392754566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 39281da177e4SLinus Torvalds 39297e53cac4SNeilBrown retry: 3930afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 393154566b2cSNick Piggin flags, &page, &fsdata); 39321da177e4SLinus Torvalds if (err) 3933afddba49SNick Piggin goto fail; 3934afddba49SNick Piggin 3935e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 39361da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 3937e8e3c3d6SCong Wang kunmap_atomic(kaddr); 3938afddba49SNick Piggin 3939afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 3940afddba49SNick Piggin page, fsdata); 39411da177e4SLinus Torvalds if (err < 0) 39421da177e4SLinus Torvalds goto fail; 3943afddba49SNick Piggin if (err < len-1) 3944afddba49SNick Piggin goto retry; 3945afddba49SNick Piggin 39461da177e4SLinus Torvalds mark_inode_dirty(inode); 39471da177e4SLinus Torvalds return 0; 39481da177e4SLinus Torvalds fail: 39491da177e4SLinus Torvalds return err; 39501da177e4SLinus Torvalds } 39511da177e4SLinus Torvalds 39520adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 39530adb25d2SKirill Korotaev { 39540adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 395554566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 39560adb25d2SKirill Korotaev } 39570adb25d2SKirill Korotaev 395892e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 39591da177e4SLinus Torvalds .readlink = generic_readlink, 39601da177e4SLinus Torvalds .follow_link = page_follow_link_light, 39611da177e4SLinus Torvalds .put_link = page_put_link, 39621da177e4SLinus Torvalds }; 39631da177e4SLinus Torvalds 39642d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 3965cc53ce53SDavid Howells EXPORT_SYMBOL(follow_down_one); 39661da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 39671da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 39681da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 39691da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 39701da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 39711da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 39721da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 39731da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 39741da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 39750adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 39761da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 39771da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 3978d1811465SAl Viro EXPORT_SYMBOL(kern_path); 397916f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 3980f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 39811da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 39821da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 39831da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 39841da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 39851da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 39861da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 39871da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 39881da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 39891da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 39901da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 39911da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 39921da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 39931da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 39941da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 3995