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> 181da177e4SLinus Torvalds #include <linux/module.h> 191da177e4SLinus Torvalds #include <linux/slab.h> 201da177e4SLinus Torvalds #include <linux/fs.h> 211da177e4SLinus Torvalds #include <linux/namei.h> 221da177e4SLinus Torvalds #include <linux/quotaops.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> 271da177e4SLinus Torvalds #include <linux/syscalls.h> 281da177e4SLinus Torvalds #include <linux/mount.h> 291da177e4SLinus Torvalds #include <linux/audit.h> 3016f7e0feSRandy Dunlap #include <linux/capability.h> 31834f2a4aSTrond Myklebust #include <linux/file.h> 325590ff0dSUlrich Drepper #include <linux/fcntl.h> 3308ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 341da177e4SLinus Torvalds #include <asm/namei.h> 351da177e4SLinus Torvalds #include <asm/uaccess.h> 361da177e4SLinus Torvalds 371da177e4SLinus Torvalds #define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE]) 381da177e4SLinus Torvalds 391da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 401da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 411da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 421da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 431da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 441da177e4SLinus Torvalds * 451da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 461da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 471da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 481da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 491da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 501da177e4SLinus Torvalds * the special cases of the former code. 511da177e4SLinus Torvalds * 521da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 531da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 541da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 551da177e4SLinus Torvalds * 561da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 571da177e4SLinus Torvalds * resolution to correspond with current state of the code. 581da177e4SLinus Torvalds * 591da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 601da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 611da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 621da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 631da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 641da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 651da177e4SLinus Torvalds */ 661da177e4SLinus Torvalds 671da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 681da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 691da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 701da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 711da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 721da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 731da177e4SLinus Torvalds * the name is a symlink pointing to a non-existant name. 741da177e4SLinus Torvalds * 751da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 761da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 771da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 781da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 791da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 801da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 811da177e4SLinus Torvalds * and in the old Linux semantics. 821da177e4SLinus Torvalds */ 831da177e4SLinus Torvalds 841da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 851da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 861da177e4SLinus Torvalds * 871da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 881da177e4SLinus Torvalds */ 891da177e4SLinus Torvalds 901da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 911da177e4SLinus Torvalds * inside the path - always follow. 921da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 931da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 941da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 951da177e4SLinus Torvalds * otherwise - don't follow. 961da177e4SLinus Torvalds * (applied in that order). 971da177e4SLinus Torvalds * 981da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 991da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1001da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1011da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1021da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1031da177e4SLinus Torvalds */ 1041da177e4SLinus Torvalds /* 1051da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 106a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1071da177e4SLinus Torvalds * any extra contention... 1081da177e4SLinus Torvalds */ 1091da177e4SLinus Torvalds 110a02f76c3SAl Viro static int __link_path_walk(const char *name, struct nameidata *nd); 111c4a7808fSJosef 'Jeff' Sipek 1121da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1131da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1141da177e4SLinus Torvalds * kernel data space before using them.. 1151da177e4SLinus Torvalds * 1161da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1171da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1181da177e4SLinus Torvalds */ 119858119e1SArjan van de Ven static int do_getname(const char __user *filename, char *page) 1201da177e4SLinus Torvalds { 1211da177e4SLinus Torvalds int retval; 1221da177e4SLinus Torvalds unsigned long len = PATH_MAX; 1231da177e4SLinus Torvalds 1241da177e4SLinus Torvalds if (!segment_eq(get_fs(), KERNEL_DS)) { 1251da177e4SLinus Torvalds if ((unsigned long) filename >= TASK_SIZE) 1261da177e4SLinus Torvalds return -EFAULT; 1271da177e4SLinus Torvalds if (TASK_SIZE - (unsigned long) filename < PATH_MAX) 1281da177e4SLinus Torvalds len = TASK_SIZE - (unsigned long) filename; 1291da177e4SLinus Torvalds } 1301da177e4SLinus Torvalds 1311da177e4SLinus Torvalds retval = strncpy_from_user(page, filename, len); 1321da177e4SLinus Torvalds if (retval > 0) { 1331da177e4SLinus Torvalds if (retval < len) 1341da177e4SLinus Torvalds return 0; 1351da177e4SLinus Torvalds return -ENAMETOOLONG; 1361da177e4SLinus Torvalds } else if (!retval) 1371da177e4SLinus Torvalds retval = -ENOENT; 1381da177e4SLinus Torvalds return retval; 1391da177e4SLinus Torvalds } 1401da177e4SLinus Torvalds 1411da177e4SLinus Torvalds char * getname(const char __user * filename) 1421da177e4SLinus Torvalds { 1431da177e4SLinus Torvalds char *tmp, *result; 1441da177e4SLinus Torvalds 1451da177e4SLinus Torvalds result = ERR_PTR(-ENOMEM); 1461da177e4SLinus Torvalds tmp = __getname(); 1471da177e4SLinus Torvalds if (tmp) { 1481da177e4SLinus Torvalds int retval = do_getname(filename, tmp); 1491da177e4SLinus Torvalds 1501da177e4SLinus Torvalds result = tmp; 1511da177e4SLinus Torvalds if (retval < 0) { 1521da177e4SLinus Torvalds __putname(tmp); 1531da177e4SLinus Torvalds result = ERR_PTR(retval); 1541da177e4SLinus Torvalds } 1551da177e4SLinus Torvalds } 1561da177e4SLinus Torvalds audit_getname(result); 1571da177e4SLinus Torvalds return result; 1581da177e4SLinus Torvalds } 1591da177e4SLinus Torvalds 1601da177e4SLinus Torvalds #ifdef CONFIG_AUDITSYSCALL 1611da177e4SLinus Torvalds void putname(const char *name) 1621da177e4SLinus Torvalds { 1635ac3a9c2SAl Viro if (unlikely(!audit_dummy_context())) 1641da177e4SLinus Torvalds audit_putname(name); 1651da177e4SLinus Torvalds else 1661da177e4SLinus Torvalds __putname(name); 1671da177e4SLinus Torvalds } 1681da177e4SLinus Torvalds EXPORT_SYMBOL(putname); 1691da177e4SLinus Torvalds #endif 1701da177e4SLinus Torvalds 1711da177e4SLinus Torvalds 1721da177e4SLinus Torvalds /** 1731da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 1741da177e4SLinus Torvalds * @inode: inode to check access rights for 1751da177e4SLinus Torvalds * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 1761da177e4SLinus Torvalds * @check_acl: optional callback to check for Posix ACLs 1771da177e4SLinus Torvalds * 1781da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 1791da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 1801da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 1811da177e4SLinus Torvalds * are used for other things.. 1821da177e4SLinus Torvalds */ 1831da177e4SLinus Torvalds int generic_permission(struct inode *inode, int mask, 1841da177e4SLinus Torvalds int (*check_acl)(struct inode *inode, int mask)) 1851da177e4SLinus Torvalds { 1861da177e4SLinus Torvalds umode_t mode = inode->i_mode; 1871da177e4SLinus Torvalds 188e6305c43SAl Viro mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 189e6305c43SAl Viro 1901da177e4SLinus Torvalds if (current->fsuid == inode->i_uid) 1911da177e4SLinus Torvalds mode >>= 6; 1921da177e4SLinus Torvalds else { 1931da177e4SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) { 1941da177e4SLinus Torvalds int error = check_acl(inode, mask); 1951da177e4SLinus Torvalds if (error == -EACCES) 1961da177e4SLinus Torvalds goto check_capabilities; 1971da177e4SLinus Torvalds else if (error != -EAGAIN) 1981da177e4SLinus Torvalds return error; 1991da177e4SLinus Torvalds } 2001da177e4SLinus Torvalds 2011da177e4SLinus Torvalds if (in_group_p(inode->i_gid)) 2021da177e4SLinus Torvalds mode >>= 3; 2031da177e4SLinus Torvalds } 2041da177e4SLinus Torvalds 2051da177e4SLinus Torvalds /* 2061da177e4SLinus Torvalds * If the DACs are ok we don't need any capability check. 2071da177e4SLinus Torvalds */ 208e6305c43SAl Viro if ((mask & ~mode) == 0) 2091da177e4SLinus Torvalds return 0; 2101da177e4SLinus Torvalds 2111da177e4SLinus Torvalds check_capabilities: 2121da177e4SLinus Torvalds /* 2131da177e4SLinus Torvalds * Read/write DACs are always overridable. 2141da177e4SLinus Torvalds * Executable DACs are overridable if at least one exec bit is set. 2151da177e4SLinus Torvalds */ 2161da177e4SLinus Torvalds if (!(mask & MAY_EXEC) || 2171da177e4SLinus Torvalds (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode)) 2181da177e4SLinus Torvalds if (capable(CAP_DAC_OVERRIDE)) 2191da177e4SLinus Torvalds return 0; 2201da177e4SLinus Torvalds 2211da177e4SLinus Torvalds /* 2221da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 2231da177e4SLinus Torvalds */ 2241da177e4SLinus Torvalds if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))) 2251da177e4SLinus Torvalds if (capable(CAP_DAC_READ_SEARCH)) 2261da177e4SLinus Torvalds return 0; 2271da177e4SLinus Torvalds 2281da177e4SLinus Torvalds return -EACCES; 2291da177e4SLinus Torvalds } 2301da177e4SLinus Torvalds 2311da177e4SLinus Torvalds int permission(struct inode *inode, int mask, struct nameidata *nd) 2321da177e4SLinus Torvalds { 233e6305c43SAl Viro int retval; 234c7eb2667SDave Hansen struct vfsmount *mnt = NULL; 235c7eb2667SDave Hansen 236c7eb2667SDave Hansen if (nd) 2374ac91378SJan Blunck mnt = nd->path.mnt; 2381da177e4SLinus Torvalds 2391da177e4SLinus Torvalds if (mask & MAY_WRITE) { 24022590e41SMiklos Szeredi umode_t mode = inode->i_mode; 2411da177e4SLinus Torvalds 2421da177e4SLinus Torvalds /* 2431da177e4SLinus Torvalds * Nobody gets write access to a read-only fs. 2441da177e4SLinus Torvalds */ 2451da177e4SLinus Torvalds if (IS_RDONLY(inode) && 2461da177e4SLinus Torvalds (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 2471da177e4SLinus Torvalds return -EROFS; 2481da177e4SLinus Torvalds 2491da177e4SLinus Torvalds /* 2501da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 2511da177e4SLinus Torvalds */ 2521da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 2531da177e4SLinus Torvalds return -EACCES; 2541da177e4SLinus Torvalds } 2551da177e4SLinus Torvalds 25622590e41SMiklos Szeredi if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode)) { 257a343bb77STrond Myklebust /* 25822590e41SMiklos Szeredi * MAY_EXEC on regular files is denied if the fs is mounted 25922590e41SMiklos Szeredi * with the "noexec" flag. 260a343bb77STrond Myklebust */ 261c7eb2667SDave Hansen if (mnt && (mnt->mnt_flags & MNT_NOEXEC)) 262a343bb77STrond Myklebust return -EACCES; 26322590e41SMiklos Szeredi } 264a343bb77STrond Myklebust 2651da177e4SLinus Torvalds /* Ordinary permission routines do not understand MAY_APPEND. */ 26622590e41SMiklos Szeredi if (inode->i_op && inode->i_op->permission) { 267e6305c43SAl Viro int extra = 0; 268e6305c43SAl Viro if (nd) { 269e6305c43SAl Viro if (nd->flags & LOOKUP_ACCESS) 270e6305c43SAl Viro extra |= MAY_ACCESS; 271e6305c43SAl Viro if (nd->flags & LOOKUP_CHDIR) 272e6305c43SAl Viro extra |= MAY_CHDIR; 273e6305c43SAl Viro if (nd->flags & LOOKUP_OPEN) 274e6305c43SAl Viro extra |= MAY_OPEN; 275e6305c43SAl Viro } 276e6305c43SAl Viro retval = inode->i_op->permission(inode, mask | extra); 27722590e41SMiklos Szeredi if (!retval) { 27822590e41SMiklos Szeredi /* 27922590e41SMiklos Szeredi * Exec permission on a regular file is denied if none 28022590e41SMiklos Szeredi * of the execute bits are set. 28122590e41SMiklos Szeredi * 28222590e41SMiklos Szeredi * This check should be done by the ->permission() 28322590e41SMiklos Szeredi * method. 28422590e41SMiklos Szeredi */ 28522590e41SMiklos Szeredi if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode) && 28622590e41SMiklos Szeredi !(inode->i_mode & S_IXUGO)) 28722590e41SMiklos Szeredi return -EACCES; 28822590e41SMiklos Szeredi } 28922590e41SMiklos Szeredi } else { 290e6305c43SAl Viro retval = generic_permission(inode, mask, NULL); 29122590e41SMiklos Szeredi } 2921da177e4SLinus Torvalds if (retval) 2931da177e4SLinus Torvalds return retval; 2941da177e4SLinus Torvalds 29508ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 29608ce5f16SSerge E. Hallyn if (retval) 29708ce5f16SSerge E. Hallyn return retval; 29808ce5f16SSerge E. Hallyn 299e6305c43SAl Viro return security_inode_permission(inode, 300e6305c43SAl Viro mask & (MAY_READ|MAY_WRITE|MAY_EXEC), nd); 3011da177e4SLinus Torvalds } 3021da177e4SLinus Torvalds 303e4543eddSChristoph Hellwig /** 304e4543eddSChristoph Hellwig * vfs_permission - check for access rights to a given path 305e4543eddSChristoph Hellwig * @nd: lookup result that describes the path 306e4543eddSChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 307e4543eddSChristoph Hellwig * 308e4543eddSChristoph Hellwig * Used to check for read/write/execute permissions on a path. 309e4543eddSChristoph Hellwig * We use "fsuid" for this, letting us set arbitrary permissions 310e4543eddSChristoph Hellwig * for filesystem access without changing the "normal" uids which 311e4543eddSChristoph Hellwig * are used for other things. 312e4543eddSChristoph Hellwig */ 313e4543eddSChristoph Hellwig int vfs_permission(struct nameidata *nd, int mask) 314e4543eddSChristoph Hellwig { 3154ac91378SJan Blunck return permission(nd->path.dentry->d_inode, mask, nd); 316e4543eddSChristoph Hellwig } 317e4543eddSChristoph Hellwig 3188c744fb8SChristoph Hellwig /** 3198c744fb8SChristoph Hellwig * file_permission - check for additional access rights to a given file 3208c744fb8SChristoph Hellwig * @file: file to check access rights for 3218c744fb8SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 3228c744fb8SChristoph Hellwig * 3238c744fb8SChristoph Hellwig * Used to check for read/write/execute permissions on an already opened 3248c744fb8SChristoph Hellwig * file. 3258c744fb8SChristoph Hellwig * 3268c744fb8SChristoph Hellwig * Note: 3278c744fb8SChristoph Hellwig * Do not use this function in new code. All access checks should 3288c744fb8SChristoph Hellwig * be done using vfs_permission(). 3298c744fb8SChristoph Hellwig */ 3308c744fb8SChristoph Hellwig int file_permission(struct file *file, int mask) 3318c744fb8SChristoph Hellwig { 3320f7fc9e4SJosef "Jeff" Sipek return permission(file->f_path.dentry->d_inode, mask, NULL); 3338c744fb8SChristoph Hellwig } 3348c744fb8SChristoph Hellwig 3351da177e4SLinus Torvalds /* 3361da177e4SLinus Torvalds * get_write_access() gets write permission for a file. 3371da177e4SLinus Torvalds * put_write_access() releases this write permission. 3381da177e4SLinus Torvalds * This is used for regular files. 3391da177e4SLinus Torvalds * We cannot support write (and maybe mmap read-write shared) accesses and 3401da177e4SLinus Torvalds * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode 3411da177e4SLinus Torvalds * can have the following values: 3421da177e4SLinus Torvalds * 0: no writers, no VM_DENYWRITE mappings 3431da177e4SLinus Torvalds * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist 3441da177e4SLinus Torvalds * > 0: (i_writecount) users are writing to the file. 3451da177e4SLinus Torvalds * 3461da177e4SLinus Torvalds * Normally we operate on that counter with atomic_{inc,dec} and it's safe 3471da177e4SLinus Torvalds * except for the cases where we don't hold i_writecount yet. Then we need to 3481da177e4SLinus Torvalds * use {get,deny}_write_access() - these functions check the sign and refuse 3491da177e4SLinus Torvalds * to do the change if sign is wrong. Exclusion between them is provided by 3501da177e4SLinus Torvalds * the inode->i_lock spinlock. 3511da177e4SLinus Torvalds */ 3521da177e4SLinus Torvalds 3531da177e4SLinus Torvalds int get_write_access(struct inode * inode) 3541da177e4SLinus Torvalds { 3551da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3561da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) < 0) { 3571da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3581da177e4SLinus Torvalds return -ETXTBSY; 3591da177e4SLinus Torvalds } 3601da177e4SLinus Torvalds atomic_inc(&inode->i_writecount); 3611da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3621da177e4SLinus Torvalds 3631da177e4SLinus Torvalds return 0; 3641da177e4SLinus Torvalds } 3651da177e4SLinus Torvalds 3661da177e4SLinus Torvalds int deny_write_access(struct file * file) 3671da177e4SLinus Torvalds { 3680f7fc9e4SJosef "Jeff" Sipek struct inode *inode = file->f_path.dentry->d_inode; 3691da177e4SLinus Torvalds 3701da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3711da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) > 0) { 3721da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3731da177e4SLinus Torvalds return -ETXTBSY; 3741da177e4SLinus Torvalds } 3751da177e4SLinus Torvalds atomic_dec(&inode->i_writecount); 3761da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3771da177e4SLinus Torvalds 3781da177e4SLinus Torvalds return 0; 3791da177e4SLinus Torvalds } 3801da177e4SLinus Torvalds 3811d957f9bSJan Blunck /** 3825dd784d0SJan Blunck * path_get - get a reference to a path 3835dd784d0SJan Blunck * @path: path to get the reference to 3845dd784d0SJan Blunck * 3855dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 3865dd784d0SJan Blunck */ 3875dd784d0SJan Blunck void path_get(struct path *path) 3885dd784d0SJan Blunck { 3895dd784d0SJan Blunck mntget(path->mnt); 3905dd784d0SJan Blunck dget(path->dentry); 3915dd784d0SJan Blunck } 3925dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 3935dd784d0SJan Blunck 3945dd784d0SJan Blunck /** 3951d957f9bSJan Blunck * path_put - put a reference to a path 3961d957f9bSJan Blunck * @path: path to put the reference to 3971d957f9bSJan Blunck * 3981d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 3991d957f9bSJan Blunck */ 4001d957f9bSJan Blunck void path_put(struct path *path) 4011da177e4SLinus Torvalds { 4021d957f9bSJan Blunck dput(path->dentry); 4031d957f9bSJan Blunck mntput(path->mnt); 4041da177e4SLinus Torvalds } 4051d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4061da177e4SLinus Torvalds 407834f2a4aSTrond Myklebust /** 408834f2a4aSTrond Myklebust * release_open_intent - free up open intent resources 409834f2a4aSTrond Myklebust * @nd: pointer to nameidata 410834f2a4aSTrond Myklebust */ 411834f2a4aSTrond Myklebust void release_open_intent(struct nameidata *nd) 412834f2a4aSTrond Myklebust { 4130f7fc9e4SJosef "Jeff" Sipek if (nd->intent.open.file->f_path.dentry == NULL) 414834f2a4aSTrond Myklebust put_filp(nd->intent.open.file); 415834f2a4aSTrond Myklebust else 416834f2a4aSTrond Myklebust fput(nd->intent.open.file); 417834f2a4aSTrond Myklebust } 418834f2a4aSTrond Myklebust 419bcdc5e01SIan Kent static inline struct dentry * 420bcdc5e01SIan Kent do_revalidate(struct dentry *dentry, struct nameidata *nd) 421bcdc5e01SIan Kent { 422bcdc5e01SIan Kent int status = dentry->d_op->d_revalidate(dentry, nd); 423bcdc5e01SIan Kent if (unlikely(status <= 0)) { 424bcdc5e01SIan Kent /* 425bcdc5e01SIan Kent * The dentry failed validation. 426bcdc5e01SIan Kent * If d_revalidate returned 0 attempt to invalidate 427bcdc5e01SIan Kent * the dentry otherwise d_revalidate is asking us 428bcdc5e01SIan Kent * to return a fail status. 429bcdc5e01SIan Kent */ 430bcdc5e01SIan Kent if (!status) { 431bcdc5e01SIan Kent if (!d_invalidate(dentry)) { 432bcdc5e01SIan Kent dput(dentry); 433bcdc5e01SIan Kent dentry = NULL; 434bcdc5e01SIan Kent } 435bcdc5e01SIan Kent } else { 436bcdc5e01SIan Kent dput(dentry); 437bcdc5e01SIan Kent dentry = ERR_PTR(status); 438bcdc5e01SIan Kent } 439bcdc5e01SIan Kent } 440bcdc5e01SIan Kent return dentry; 441bcdc5e01SIan Kent } 442bcdc5e01SIan Kent 4431da177e4SLinus Torvalds /* 4441da177e4SLinus Torvalds * Internal lookup() using the new generic dcache. 4451da177e4SLinus Torvalds * SMP-safe 4461da177e4SLinus Torvalds */ 4471da177e4SLinus Torvalds static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) 4481da177e4SLinus Torvalds { 4491da177e4SLinus Torvalds struct dentry * dentry = __d_lookup(parent, name); 4501da177e4SLinus Torvalds 4511da177e4SLinus Torvalds /* lockess __d_lookup may fail due to concurrent d_move() 4521da177e4SLinus Torvalds * in some unrelated directory, so try with d_lookup 4531da177e4SLinus Torvalds */ 4541da177e4SLinus Torvalds if (!dentry) 4551da177e4SLinus Torvalds dentry = d_lookup(parent, name); 4561da177e4SLinus Torvalds 457bcdc5e01SIan Kent if (dentry && dentry->d_op && dentry->d_op->d_revalidate) 458bcdc5e01SIan Kent dentry = do_revalidate(dentry, nd); 459bcdc5e01SIan Kent 4601da177e4SLinus Torvalds return dentry; 4611da177e4SLinus Torvalds } 4621da177e4SLinus Torvalds 4631da177e4SLinus Torvalds /* 4641da177e4SLinus Torvalds * Short-cut version of permission(), for calling by 4651da177e4SLinus Torvalds * path_walk(), when dcache lock is held. Combines parts 4661da177e4SLinus Torvalds * of permission() and generic_permission(), and tests ONLY for 4671da177e4SLinus Torvalds * MAY_EXEC permission. 4681da177e4SLinus Torvalds * 4691da177e4SLinus Torvalds * If appropriate, check DAC only. If not appropriate, or 4701da177e4SLinus Torvalds * short-cut DAC fails, then call permission() to do more 4711da177e4SLinus Torvalds * complete permission check. 4721da177e4SLinus Torvalds */ 473858119e1SArjan van de Ven static int exec_permission_lite(struct inode *inode, 4741da177e4SLinus Torvalds struct nameidata *nd) 4751da177e4SLinus Torvalds { 4761da177e4SLinus Torvalds umode_t mode = inode->i_mode; 4771da177e4SLinus Torvalds 4781da177e4SLinus Torvalds if (inode->i_op && inode->i_op->permission) 4791da177e4SLinus Torvalds return -EAGAIN; 4801da177e4SLinus Torvalds 4811da177e4SLinus Torvalds if (current->fsuid == inode->i_uid) 4821da177e4SLinus Torvalds mode >>= 6; 4831da177e4SLinus Torvalds else if (in_group_p(inode->i_gid)) 4841da177e4SLinus Torvalds mode >>= 3; 4851da177e4SLinus Torvalds 4861da177e4SLinus Torvalds if (mode & MAY_EXEC) 4871da177e4SLinus Torvalds goto ok; 4881da177e4SLinus Torvalds 4891da177e4SLinus Torvalds if ((inode->i_mode & S_IXUGO) && capable(CAP_DAC_OVERRIDE)) 4901da177e4SLinus Torvalds goto ok; 4911da177e4SLinus Torvalds 4921da177e4SLinus Torvalds if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_OVERRIDE)) 4931da177e4SLinus Torvalds goto ok; 4941da177e4SLinus Torvalds 4951da177e4SLinus Torvalds if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_READ_SEARCH)) 4961da177e4SLinus Torvalds goto ok; 4971da177e4SLinus Torvalds 4981da177e4SLinus Torvalds return -EACCES; 4991da177e4SLinus Torvalds ok: 5001da177e4SLinus Torvalds return security_inode_permission(inode, MAY_EXEC, nd); 5011da177e4SLinus Torvalds } 5021da177e4SLinus Torvalds 5031da177e4SLinus Torvalds /* 5041da177e4SLinus Torvalds * This is called when everything else fails, and we actually have 5051da177e4SLinus Torvalds * to go to the low-level filesystem to find out what we should do.. 5061da177e4SLinus Torvalds * 5071da177e4SLinus Torvalds * We get the directory semaphore, and after getting that we also 5081da177e4SLinus Torvalds * make sure that nobody added the entry to the dcache in the meantime.. 5091da177e4SLinus Torvalds * SMP-safe 5101da177e4SLinus Torvalds */ 5111da177e4SLinus Torvalds static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) 5121da177e4SLinus Torvalds { 5131da177e4SLinus Torvalds struct dentry * result; 5141da177e4SLinus Torvalds struct inode *dir = parent->d_inode; 5151da177e4SLinus Torvalds 5161b1dcc1bSJes Sorensen mutex_lock(&dir->i_mutex); 5171da177e4SLinus Torvalds /* 5181da177e4SLinus Torvalds * First re-do the cached lookup just in case it was created 5191da177e4SLinus Torvalds * while we waited for the directory semaphore.. 5201da177e4SLinus Torvalds * 5211da177e4SLinus Torvalds * FIXME! This could use version numbering or similar to 5221da177e4SLinus Torvalds * avoid unnecessary cache lookups. 5231da177e4SLinus Torvalds * 5241da177e4SLinus Torvalds * The "dcache_lock" is purely to protect the RCU list walker 5251da177e4SLinus Torvalds * from concurrent renames at this point (we mustn't get false 5261da177e4SLinus Torvalds * negatives from the RCU list walk here, unlike the optimistic 5271da177e4SLinus Torvalds * fast walk). 5281da177e4SLinus Torvalds * 5291da177e4SLinus Torvalds * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup 5301da177e4SLinus Torvalds */ 5311da177e4SLinus Torvalds result = d_lookup(parent, name); 5321da177e4SLinus Torvalds if (!result) { 533d70b67c8SMiklos Szeredi struct dentry *dentry; 534d70b67c8SMiklos Szeredi 535d70b67c8SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 536d70b67c8SMiklos Szeredi result = ERR_PTR(-ENOENT); 537d70b67c8SMiklos Szeredi if (IS_DEADDIR(dir)) 538d70b67c8SMiklos Szeredi goto out_unlock; 539d70b67c8SMiklos Szeredi 540d70b67c8SMiklos Szeredi dentry = d_alloc(parent, name); 5411da177e4SLinus Torvalds result = ERR_PTR(-ENOMEM); 5421da177e4SLinus Torvalds if (dentry) { 5431da177e4SLinus Torvalds result = dir->i_op->lookup(dir, dentry, nd); 5441da177e4SLinus Torvalds if (result) 5451da177e4SLinus Torvalds dput(dentry); 5461da177e4SLinus Torvalds else 5471da177e4SLinus Torvalds result = dentry; 5481da177e4SLinus Torvalds } 549d70b67c8SMiklos Szeredi out_unlock: 5501b1dcc1bSJes Sorensen mutex_unlock(&dir->i_mutex); 5511da177e4SLinus Torvalds return result; 5521da177e4SLinus Torvalds } 5531da177e4SLinus Torvalds 5541da177e4SLinus Torvalds /* 5551da177e4SLinus Torvalds * Uhhuh! Nasty case: the cache was re-populated while 5561da177e4SLinus Torvalds * we waited on the semaphore. Need to revalidate. 5571da177e4SLinus Torvalds */ 5581b1dcc1bSJes Sorensen mutex_unlock(&dir->i_mutex); 5591da177e4SLinus Torvalds if (result->d_op && result->d_op->d_revalidate) { 560bcdc5e01SIan Kent result = do_revalidate(result, nd); 561bcdc5e01SIan Kent if (!result) 5621da177e4SLinus Torvalds result = ERR_PTR(-ENOENT); 5631da177e4SLinus Torvalds } 5641da177e4SLinus Torvalds return result; 5651da177e4SLinus Torvalds } 5661da177e4SLinus Torvalds 5671da177e4SLinus Torvalds static int __emul_lookup_dentry(const char *, struct nameidata *); 5681da177e4SLinus Torvalds 5691da177e4SLinus Torvalds /* SMP-safe */ 570f1662356SArjan van de Ven static __always_inline int 5711da177e4SLinus Torvalds walk_init_root(const char *name, struct nameidata *nd) 5721da177e4SLinus Torvalds { 573e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 574e518ddb7SAndreas Mohr 575e518ddb7SAndreas Mohr read_lock(&fs->lock); 5766ac08c39SJan Blunck if (fs->altroot.dentry && !(nd->flags & LOOKUP_NOALT)) { 5776ac08c39SJan Blunck nd->path = fs->altroot; 5786ac08c39SJan Blunck path_get(&fs->altroot); 579e518ddb7SAndreas Mohr read_unlock(&fs->lock); 5801da177e4SLinus Torvalds if (__emul_lookup_dentry(name,nd)) 5811da177e4SLinus Torvalds return 0; 582e518ddb7SAndreas Mohr read_lock(&fs->lock); 5831da177e4SLinus Torvalds } 5846ac08c39SJan Blunck nd->path = fs->root; 5856ac08c39SJan Blunck path_get(&fs->root); 586e518ddb7SAndreas Mohr read_unlock(&fs->lock); 5871da177e4SLinus Torvalds return 1; 5881da177e4SLinus Torvalds } 5891da177e4SLinus Torvalds 590a02f76c3SAl Viro /* 591a02f76c3SAl Viro * Wrapper to retry pathname resolution whenever the underlying 592a02f76c3SAl Viro * file system returns an ESTALE. 593a02f76c3SAl Viro * 594a02f76c3SAl Viro * Retry the whole path once, forcing real lookup requests 595a02f76c3SAl Viro * instead of relying on the dcache. 596a02f76c3SAl Viro */ 597a02f76c3SAl Viro static __always_inline int link_path_walk(const char *name, struct nameidata *nd) 598a02f76c3SAl Viro { 599a02f76c3SAl Viro struct path save = nd->path; 600a02f76c3SAl Viro int result; 601a02f76c3SAl Viro 602a02f76c3SAl Viro /* make sure the stuff we saved doesn't go away */ 603c8e7f449SJan Blunck path_get(&save); 604a02f76c3SAl Viro 605a02f76c3SAl Viro result = __link_path_walk(name, nd); 606a02f76c3SAl Viro if (result == -ESTALE) { 607a02f76c3SAl Viro /* nd->path had been dropped */ 608a02f76c3SAl Viro nd->path = save; 609c8e7f449SJan Blunck path_get(&nd->path); 610a02f76c3SAl Viro nd->flags |= LOOKUP_REVAL; 611a02f76c3SAl Viro result = __link_path_walk(name, nd); 612a02f76c3SAl Viro } 613a02f76c3SAl Viro 614a02f76c3SAl Viro path_put(&save); 615a02f76c3SAl Viro 616a02f76c3SAl Viro return result; 617a02f76c3SAl Viro } 618a02f76c3SAl Viro 619f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 6201da177e4SLinus Torvalds { 6211da177e4SLinus Torvalds int res = 0; 6221da177e4SLinus Torvalds char *name; 6231da177e4SLinus Torvalds if (IS_ERR(link)) 6241da177e4SLinus Torvalds goto fail; 6251da177e4SLinus Torvalds 6261da177e4SLinus Torvalds if (*link == '/') { 6271d957f9bSJan Blunck path_put(&nd->path); 6281da177e4SLinus Torvalds if (!walk_init_root(link, nd)) 6291da177e4SLinus Torvalds /* weird __emul_prefix() stuff did it */ 6301da177e4SLinus Torvalds goto out; 6311da177e4SLinus Torvalds } 6321da177e4SLinus Torvalds res = link_path_walk(link, nd); 6331da177e4SLinus Torvalds out: 6341da177e4SLinus Torvalds if (nd->depth || res || nd->last_type!=LAST_NORM) 6351da177e4SLinus Torvalds return res; 6361da177e4SLinus Torvalds /* 6371da177e4SLinus Torvalds * If it is an iterative symlinks resolution in open_namei() we 6381da177e4SLinus Torvalds * have to copy the last component. And all that crap because of 6391da177e4SLinus Torvalds * bloody create() on broken symlinks. Furrfu... 6401da177e4SLinus Torvalds */ 6411da177e4SLinus Torvalds name = __getname(); 6421da177e4SLinus Torvalds if (unlikely(!name)) { 6431d957f9bSJan Blunck path_put(&nd->path); 6441da177e4SLinus Torvalds return -ENOMEM; 6451da177e4SLinus Torvalds } 6461da177e4SLinus Torvalds strcpy(name, nd->last.name); 6471da177e4SLinus Torvalds nd->last.name = name; 6481da177e4SLinus Torvalds return 0; 6491da177e4SLinus Torvalds fail: 6501d957f9bSJan Blunck path_put(&nd->path); 6511da177e4SLinus Torvalds return PTR_ERR(link); 6521da177e4SLinus Torvalds } 6531da177e4SLinus Torvalds 6541d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 655051d3812SIan Kent { 656051d3812SIan Kent dput(path->dentry); 6574ac91378SJan Blunck if (path->mnt != nd->path.mnt) 658051d3812SIan Kent mntput(path->mnt); 659051d3812SIan Kent } 660051d3812SIan Kent 661051d3812SIan Kent static inline void path_to_nameidata(struct path *path, struct nameidata *nd) 662051d3812SIan Kent { 6634ac91378SJan Blunck dput(nd->path.dentry); 6644ac91378SJan Blunck if (nd->path.mnt != path->mnt) 6654ac91378SJan Blunck mntput(nd->path.mnt); 6664ac91378SJan Blunck nd->path.mnt = path->mnt; 6674ac91378SJan Blunck nd->path.dentry = path->dentry; 668051d3812SIan Kent } 669051d3812SIan Kent 670f1662356SArjan van de Ven static __always_inline int __do_follow_link(struct path *path, struct nameidata *nd) 6711da177e4SLinus Torvalds { 6721da177e4SLinus Torvalds int error; 673cc314eefSLinus Torvalds void *cookie; 674cd4e91d3SAl Viro struct dentry *dentry = path->dentry; 6751da177e4SLinus Torvalds 676d671a1cbSAl Viro touch_atime(path->mnt, dentry); 6771da177e4SLinus Torvalds nd_set_link(nd, NULL); 678cd4e91d3SAl Viro 6794ac91378SJan Blunck if (path->mnt != nd->path.mnt) { 680051d3812SIan Kent path_to_nameidata(path, nd); 681051d3812SIan Kent dget(dentry); 682051d3812SIan Kent } 683cd4e91d3SAl Viro mntget(path->mnt); 684cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, nd); 685cc314eefSLinus Torvalds error = PTR_ERR(cookie); 686cc314eefSLinus Torvalds if (!IS_ERR(cookie)) { 6871da177e4SLinus Torvalds char *s = nd_get_link(nd); 688cc314eefSLinus Torvalds error = 0; 6891da177e4SLinus Torvalds if (s) 6901da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 6911da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 692cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, nd, cookie); 6931da177e4SLinus Torvalds } 69409da5916SJan Blunck path_put(path); 6951da177e4SLinus Torvalds 6961da177e4SLinus Torvalds return error; 6971da177e4SLinus Torvalds } 6981da177e4SLinus Torvalds 6991da177e4SLinus Torvalds /* 7001da177e4SLinus Torvalds * This limits recursive symlink follows to 8, while 7011da177e4SLinus Torvalds * limiting consecutive symlinks to 40. 7021da177e4SLinus Torvalds * 7031da177e4SLinus Torvalds * Without that kind of total limit, nasty chains of consecutive 7041da177e4SLinus Torvalds * symlinks can cause almost arbitrarily long lookups. 7051da177e4SLinus Torvalds */ 70690ebe565SAl Viro static inline int do_follow_link(struct path *path, struct nameidata *nd) 7071da177e4SLinus Torvalds { 7081da177e4SLinus Torvalds int err = -ELOOP; 7091da177e4SLinus Torvalds if (current->link_count >= MAX_NESTED_LINKS) 7101da177e4SLinus Torvalds goto loop; 7111da177e4SLinus Torvalds if (current->total_link_count >= 40) 7121da177e4SLinus Torvalds goto loop; 7131da177e4SLinus Torvalds BUG_ON(nd->depth >= MAX_NESTED_LINKS); 7141da177e4SLinus Torvalds cond_resched(); 71590ebe565SAl Viro err = security_inode_follow_link(path->dentry, nd); 7161da177e4SLinus Torvalds if (err) 7171da177e4SLinus Torvalds goto loop; 7181da177e4SLinus Torvalds current->link_count++; 7191da177e4SLinus Torvalds current->total_link_count++; 7201da177e4SLinus Torvalds nd->depth++; 721cd4e91d3SAl Viro err = __do_follow_link(path, nd); 7221da177e4SLinus Torvalds current->link_count--; 7231da177e4SLinus Torvalds nd->depth--; 7241da177e4SLinus Torvalds return err; 7251da177e4SLinus Torvalds loop: 7261d957f9bSJan Blunck path_put_conditional(path, nd); 7271d957f9bSJan Blunck path_put(&nd->path); 7281da177e4SLinus Torvalds return err; 7291da177e4SLinus Torvalds } 7301da177e4SLinus Torvalds 7311da177e4SLinus Torvalds int follow_up(struct vfsmount **mnt, struct dentry **dentry) 7321da177e4SLinus Torvalds { 7331da177e4SLinus Torvalds struct vfsmount *parent; 7341da177e4SLinus Torvalds struct dentry *mountpoint; 7351da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 7361da177e4SLinus Torvalds parent=(*mnt)->mnt_parent; 7371da177e4SLinus Torvalds if (parent == *mnt) { 7381da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7391da177e4SLinus Torvalds return 0; 7401da177e4SLinus Torvalds } 7411da177e4SLinus Torvalds mntget(parent); 7421da177e4SLinus Torvalds mountpoint=dget((*mnt)->mnt_mountpoint); 7431da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7441da177e4SLinus Torvalds dput(*dentry); 7451da177e4SLinus Torvalds *dentry = mountpoint; 7461da177e4SLinus Torvalds mntput(*mnt); 7471da177e4SLinus Torvalds *mnt = parent; 7481da177e4SLinus Torvalds return 1; 7491da177e4SLinus Torvalds } 7501da177e4SLinus Torvalds 7511da177e4SLinus Torvalds /* no need for dcache_lock, as serialization is taken care in 7521da177e4SLinus Torvalds * namespace.c 7531da177e4SLinus Torvalds */ 754463ffb2eSAl Viro static int __follow_mount(struct path *path) 755463ffb2eSAl Viro { 756463ffb2eSAl Viro int res = 0; 757463ffb2eSAl Viro while (d_mountpoint(path->dentry)) { 758463ffb2eSAl Viro struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry); 759463ffb2eSAl Viro if (!mounted) 760463ffb2eSAl Viro break; 761463ffb2eSAl Viro dput(path->dentry); 762463ffb2eSAl Viro if (res) 763463ffb2eSAl Viro mntput(path->mnt); 764463ffb2eSAl Viro path->mnt = mounted; 765463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 766463ffb2eSAl Viro res = 1; 767463ffb2eSAl Viro } 768463ffb2eSAl Viro return res; 769463ffb2eSAl Viro } 770463ffb2eSAl Viro 77158c465ebSAl Viro static void follow_mount(struct vfsmount **mnt, struct dentry **dentry) 7721da177e4SLinus Torvalds { 7731da177e4SLinus Torvalds while (d_mountpoint(*dentry)) { 7741da177e4SLinus Torvalds struct vfsmount *mounted = lookup_mnt(*mnt, *dentry); 7751da177e4SLinus Torvalds if (!mounted) 7761da177e4SLinus Torvalds break; 77758c465ebSAl Viro dput(*dentry); 7781da177e4SLinus Torvalds mntput(*mnt); 7791da177e4SLinus Torvalds *mnt = mounted; 7801da177e4SLinus Torvalds *dentry = dget(mounted->mnt_root); 7811da177e4SLinus Torvalds } 7821da177e4SLinus Torvalds } 7831da177e4SLinus Torvalds 7841da177e4SLinus Torvalds /* no need for dcache_lock, as serialization is taken care in 7851da177e4SLinus Torvalds * namespace.c 7861da177e4SLinus Torvalds */ 787e13b210fSAl Viro int follow_down(struct vfsmount **mnt, struct dentry **dentry) 7881da177e4SLinus Torvalds { 7891da177e4SLinus Torvalds struct vfsmount *mounted; 7901da177e4SLinus Torvalds 7911da177e4SLinus Torvalds mounted = lookup_mnt(*mnt, *dentry); 7921da177e4SLinus Torvalds if (mounted) { 793e13b210fSAl Viro dput(*dentry); 7941da177e4SLinus Torvalds mntput(*mnt); 7951da177e4SLinus Torvalds *mnt = mounted; 7961da177e4SLinus Torvalds *dentry = dget(mounted->mnt_root); 7971da177e4SLinus Torvalds return 1; 7981da177e4SLinus Torvalds } 7991da177e4SLinus Torvalds return 0; 8001da177e4SLinus Torvalds } 8011da177e4SLinus Torvalds 802f1662356SArjan van de Ven static __always_inline void follow_dotdot(struct nameidata *nd) 8031da177e4SLinus Torvalds { 804e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 805e518ddb7SAndreas Mohr 8061da177e4SLinus Torvalds while(1) { 8071da177e4SLinus Torvalds struct vfsmount *parent; 8084ac91378SJan Blunck struct dentry *old = nd->path.dentry; 8091da177e4SLinus Torvalds 810e518ddb7SAndreas Mohr read_lock(&fs->lock); 8116ac08c39SJan Blunck if (nd->path.dentry == fs->root.dentry && 8126ac08c39SJan Blunck nd->path.mnt == fs->root.mnt) { 813e518ddb7SAndreas Mohr read_unlock(&fs->lock); 8141da177e4SLinus Torvalds break; 8151da177e4SLinus Torvalds } 816e518ddb7SAndreas Mohr read_unlock(&fs->lock); 8171da177e4SLinus Torvalds spin_lock(&dcache_lock); 8184ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 8194ac91378SJan Blunck nd->path.dentry = dget(nd->path.dentry->d_parent); 8201da177e4SLinus Torvalds spin_unlock(&dcache_lock); 8211da177e4SLinus Torvalds dput(old); 8221da177e4SLinus Torvalds break; 8231da177e4SLinus Torvalds } 8241da177e4SLinus Torvalds spin_unlock(&dcache_lock); 8251da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 8264ac91378SJan Blunck parent = nd->path.mnt->mnt_parent; 8274ac91378SJan Blunck if (parent == nd->path.mnt) { 8281da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 8291da177e4SLinus Torvalds break; 8301da177e4SLinus Torvalds } 8311da177e4SLinus Torvalds mntget(parent); 8324ac91378SJan Blunck nd->path.dentry = dget(nd->path.mnt->mnt_mountpoint); 8331da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 8341da177e4SLinus Torvalds dput(old); 8354ac91378SJan Blunck mntput(nd->path.mnt); 8364ac91378SJan Blunck nd->path.mnt = parent; 8371da177e4SLinus Torvalds } 8384ac91378SJan Blunck follow_mount(&nd->path.mnt, &nd->path.dentry); 8391da177e4SLinus Torvalds } 8401da177e4SLinus Torvalds 8411da177e4SLinus Torvalds /* 8421da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 8431da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 8441da177e4SLinus Torvalds * It _is_ time-critical. 8451da177e4SLinus Torvalds */ 8461da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 8471da177e4SLinus Torvalds struct path *path) 8481da177e4SLinus Torvalds { 8494ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 8504ac91378SJan Blunck struct dentry *dentry = __d_lookup(nd->path.dentry, name); 8511da177e4SLinus Torvalds 8521da177e4SLinus Torvalds if (!dentry) 8531da177e4SLinus Torvalds goto need_lookup; 8541da177e4SLinus Torvalds if (dentry->d_op && dentry->d_op->d_revalidate) 8551da177e4SLinus Torvalds goto need_revalidate; 8561da177e4SLinus Torvalds done: 8571da177e4SLinus Torvalds path->mnt = mnt; 8581da177e4SLinus Torvalds path->dentry = dentry; 859634ee701SAl Viro __follow_mount(path); 8601da177e4SLinus Torvalds return 0; 8611da177e4SLinus Torvalds 8621da177e4SLinus Torvalds need_lookup: 8634ac91378SJan Blunck dentry = real_lookup(nd->path.dentry, name, nd); 8641da177e4SLinus Torvalds if (IS_ERR(dentry)) 8651da177e4SLinus Torvalds goto fail; 8661da177e4SLinus Torvalds goto done; 8671da177e4SLinus Torvalds 8681da177e4SLinus Torvalds need_revalidate: 869bcdc5e01SIan Kent dentry = do_revalidate(dentry, nd); 870bcdc5e01SIan Kent if (!dentry) 8711da177e4SLinus Torvalds goto need_lookup; 872bcdc5e01SIan Kent if (IS_ERR(dentry)) 873bcdc5e01SIan Kent goto fail; 874bcdc5e01SIan Kent goto done; 8751da177e4SLinus Torvalds 8761da177e4SLinus Torvalds fail: 8771da177e4SLinus Torvalds return PTR_ERR(dentry); 8781da177e4SLinus Torvalds } 8791da177e4SLinus Torvalds 8801da177e4SLinus Torvalds /* 8811da177e4SLinus Torvalds * Name resolution. 882ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 883ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 8841da177e4SLinus Torvalds * 885ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 886ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 8871da177e4SLinus Torvalds */ 888fc9b52cdSHarvey Harrison static int __link_path_walk(const char *name, struct nameidata *nd) 8891da177e4SLinus Torvalds { 8901da177e4SLinus Torvalds struct path next; 8911da177e4SLinus Torvalds struct inode *inode; 8921da177e4SLinus Torvalds int err; 8931da177e4SLinus Torvalds unsigned int lookup_flags = nd->flags; 8941da177e4SLinus Torvalds 8951da177e4SLinus Torvalds while (*name=='/') 8961da177e4SLinus Torvalds name++; 8971da177e4SLinus Torvalds if (!*name) 8981da177e4SLinus Torvalds goto return_reval; 8991da177e4SLinus Torvalds 9004ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9011da177e4SLinus Torvalds if (nd->depth) 902f55eab82STrond Myklebust lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE); 9031da177e4SLinus Torvalds 9041da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 9051da177e4SLinus Torvalds for(;;) { 9061da177e4SLinus Torvalds unsigned long hash; 9071da177e4SLinus Torvalds struct qstr this; 9081da177e4SLinus Torvalds unsigned int c; 9091da177e4SLinus Torvalds 910cdce5d6bSTrond Myklebust nd->flags |= LOOKUP_CONTINUE; 9111da177e4SLinus Torvalds err = exec_permission_lite(inode, nd); 912e4543eddSChristoph Hellwig if (err == -EAGAIN) 913e4543eddSChristoph Hellwig err = vfs_permission(nd, MAY_EXEC); 9141da177e4SLinus Torvalds if (err) 9151da177e4SLinus Torvalds break; 9161da177e4SLinus Torvalds 9171da177e4SLinus Torvalds this.name = name; 9181da177e4SLinus Torvalds c = *(const unsigned char *)name; 9191da177e4SLinus Torvalds 9201da177e4SLinus Torvalds hash = init_name_hash(); 9211da177e4SLinus Torvalds do { 9221da177e4SLinus Torvalds name++; 9231da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 9241da177e4SLinus Torvalds c = *(const unsigned char *)name; 9251da177e4SLinus Torvalds } while (c && (c != '/')); 9261da177e4SLinus Torvalds this.len = name - (const char *) this.name; 9271da177e4SLinus Torvalds this.hash = end_name_hash(hash); 9281da177e4SLinus Torvalds 9291da177e4SLinus Torvalds /* remove trailing slashes? */ 9301da177e4SLinus Torvalds if (!c) 9311da177e4SLinus Torvalds goto last_component; 9321da177e4SLinus Torvalds while (*++name == '/'); 9331da177e4SLinus Torvalds if (!*name) 9341da177e4SLinus Torvalds goto last_with_slashes; 9351da177e4SLinus Torvalds 9361da177e4SLinus Torvalds /* 9371da177e4SLinus Torvalds * "." and ".." are special - ".." especially so because it has 9381da177e4SLinus Torvalds * to be able to know about the current root directory and 9391da177e4SLinus Torvalds * parent relationships. 9401da177e4SLinus Torvalds */ 9411da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 9421da177e4SLinus Torvalds default: 9431da177e4SLinus Torvalds break; 9441da177e4SLinus Torvalds case 2: 9451da177e4SLinus Torvalds if (this.name[1] != '.') 9461da177e4SLinus Torvalds break; 94758c465ebSAl Viro follow_dotdot(nd); 9484ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9491da177e4SLinus Torvalds /* fallthrough */ 9501da177e4SLinus Torvalds case 1: 9511da177e4SLinus Torvalds continue; 9521da177e4SLinus Torvalds } 9531da177e4SLinus Torvalds /* 9541da177e4SLinus Torvalds * See if the low-level filesystem might want 9551da177e4SLinus Torvalds * to use its own hash.. 9561da177e4SLinus Torvalds */ 9574ac91378SJan Blunck if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { 9584ac91378SJan Blunck err = nd->path.dentry->d_op->d_hash(nd->path.dentry, 9594ac91378SJan Blunck &this); 9601da177e4SLinus Torvalds if (err < 0) 9611da177e4SLinus Torvalds break; 9621da177e4SLinus Torvalds } 9631da177e4SLinus Torvalds /* This does the actual lookups.. */ 9641da177e4SLinus Torvalds err = do_lookup(nd, &this, &next); 9651da177e4SLinus Torvalds if (err) 9661da177e4SLinus Torvalds break; 9671da177e4SLinus Torvalds 9681da177e4SLinus Torvalds err = -ENOENT; 9691da177e4SLinus Torvalds inode = next.dentry->d_inode; 9701da177e4SLinus Torvalds if (!inode) 9711da177e4SLinus Torvalds goto out_dput; 9721da177e4SLinus Torvalds err = -ENOTDIR; 9731da177e4SLinus Torvalds if (!inode->i_op) 9741da177e4SLinus Torvalds goto out_dput; 9751da177e4SLinus Torvalds 9761da177e4SLinus Torvalds if (inode->i_op->follow_link) { 97790ebe565SAl Viro err = do_follow_link(&next, nd); 9781da177e4SLinus Torvalds if (err) 9791da177e4SLinus Torvalds goto return_err; 9801da177e4SLinus Torvalds err = -ENOENT; 9814ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9821da177e4SLinus Torvalds if (!inode) 9831da177e4SLinus Torvalds break; 9841da177e4SLinus Torvalds err = -ENOTDIR; 9851da177e4SLinus Torvalds if (!inode->i_op) 9861da177e4SLinus Torvalds break; 98709dd17d3SMiklos Szeredi } else 98809dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 9891da177e4SLinus Torvalds err = -ENOTDIR; 9901da177e4SLinus Torvalds if (!inode->i_op->lookup) 9911da177e4SLinus Torvalds break; 9921da177e4SLinus Torvalds continue; 9931da177e4SLinus Torvalds /* here ends the main loop */ 9941da177e4SLinus Torvalds 9951da177e4SLinus Torvalds last_with_slashes: 9961da177e4SLinus Torvalds lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 9971da177e4SLinus Torvalds last_component: 998f55eab82STrond Myklebust /* Clear LOOKUP_CONTINUE iff it was previously unset */ 999f55eab82STrond Myklebust nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; 10001da177e4SLinus Torvalds if (lookup_flags & LOOKUP_PARENT) 10011da177e4SLinus Torvalds goto lookup_parent; 10021da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 10031da177e4SLinus Torvalds default: 10041da177e4SLinus Torvalds break; 10051da177e4SLinus Torvalds case 2: 10061da177e4SLinus Torvalds if (this.name[1] != '.') 10071da177e4SLinus Torvalds break; 100858c465ebSAl Viro follow_dotdot(nd); 10094ac91378SJan Blunck inode = nd->path.dentry->d_inode; 10101da177e4SLinus Torvalds /* fallthrough */ 10111da177e4SLinus Torvalds case 1: 10121da177e4SLinus Torvalds goto return_reval; 10131da177e4SLinus Torvalds } 10144ac91378SJan Blunck if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { 10154ac91378SJan Blunck err = nd->path.dentry->d_op->d_hash(nd->path.dentry, 10164ac91378SJan Blunck &this); 10171da177e4SLinus Torvalds if (err < 0) 10181da177e4SLinus Torvalds break; 10191da177e4SLinus Torvalds } 10201da177e4SLinus Torvalds err = do_lookup(nd, &this, &next); 10211da177e4SLinus Torvalds if (err) 10221da177e4SLinus Torvalds break; 10231da177e4SLinus Torvalds inode = next.dentry->d_inode; 10241da177e4SLinus Torvalds if ((lookup_flags & LOOKUP_FOLLOW) 10251da177e4SLinus Torvalds && inode && inode->i_op && inode->i_op->follow_link) { 102690ebe565SAl Viro err = do_follow_link(&next, nd); 10271da177e4SLinus Torvalds if (err) 10281da177e4SLinus Torvalds goto return_err; 10294ac91378SJan Blunck inode = nd->path.dentry->d_inode; 103009dd17d3SMiklos Szeredi } else 103109dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 10321da177e4SLinus Torvalds err = -ENOENT; 10331da177e4SLinus Torvalds if (!inode) 10341da177e4SLinus Torvalds break; 10351da177e4SLinus Torvalds if (lookup_flags & LOOKUP_DIRECTORY) { 10361da177e4SLinus Torvalds err = -ENOTDIR; 10371da177e4SLinus Torvalds if (!inode->i_op || !inode->i_op->lookup) 10381da177e4SLinus Torvalds break; 10391da177e4SLinus Torvalds } 10401da177e4SLinus Torvalds goto return_base; 10411da177e4SLinus Torvalds lookup_parent: 10421da177e4SLinus Torvalds nd->last = this; 10431da177e4SLinus Torvalds nd->last_type = LAST_NORM; 10441da177e4SLinus Torvalds if (this.name[0] != '.') 10451da177e4SLinus Torvalds goto return_base; 10461da177e4SLinus Torvalds if (this.len == 1) 10471da177e4SLinus Torvalds nd->last_type = LAST_DOT; 10481da177e4SLinus Torvalds else if (this.len == 2 && this.name[1] == '.') 10491da177e4SLinus Torvalds nd->last_type = LAST_DOTDOT; 10501da177e4SLinus Torvalds else 10511da177e4SLinus Torvalds goto return_base; 10521da177e4SLinus Torvalds return_reval: 10531da177e4SLinus Torvalds /* 10541da177e4SLinus Torvalds * We bypassed the ordinary revalidation routines. 10551da177e4SLinus Torvalds * We may need to check the cached dentry for staleness. 10561da177e4SLinus Torvalds */ 10574ac91378SJan Blunck if (nd->path.dentry && nd->path.dentry->d_sb && 10584ac91378SJan Blunck (nd->path.dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) { 10591da177e4SLinus Torvalds err = -ESTALE; 10601da177e4SLinus Torvalds /* Note: we do not d_invalidate() */ 10614ac91378SJan Blunck if (!nd->path.dentry->d_op->d_revalidate( 10624ac91378SJan Blunck nd->path.dentry, nd)) 10631da177e4SLinus Torvalds break; 10641da177e4SLinus Torvalds } 10651da177e4SLinus Torvalds return_base: 10661da177e4SLinus Torvalds return 0; 10671da177e4SLinus Torvalds out_dput: 10681d957f9bSJan Blunck path_put_conditional(&next, nd); 10691da177e4SLinus Torvalds break; 10701da177e4SLinus Torvalds } 10711d957f9bSJan Blunck path_put(&nd->path); 10721da177e4SLinus Torvalds return_err: 10731da177e4SLinus Torvalds return err; 10741da177e4SLinus Torvalds } 10751da177e4SLinus Torvalds 1076fc9b52cdSHarvey Harrison static int path_walk(const char *name, struct nameidata *nd) 10771da177e4SLinus Torvalds { 10781da177e4SLinus Torvalds current->total_link_count = 0; 10791da177e4SLinus Torvalds return link_path_walk(name, nd); 10801da177e4SLinus Torvalds } 10811da177e4SLinus Torvalds 1082ea3834d9SPrasanna Meda /* 1083ea3834d9SPrasanna Meda * SMP-safe: Returns 1 and nd will have valid dentry and mnt, if 1084ea3834d9SPrasanna Meda * everything is done. Returns 0 and drops input nd, if lookup failed; 1085ea3834d9SPrasanna Meda */ 10861da177e4SLinus Torvalds static int __emul_lookup_dentry(const char *name, struct nameidata *nd) 10871da177e4SLinus Torvalds { 10881da177e4SLinus Torvalds if (path_walk(name, nd)) 10891da177e4SLinus Torvalds return 0; /* something went wrong... */ 10901da177e4SLinus Torvalds 10914ac91378SJan Blunck if (!nd->path.dentry->d_inode || 10924ac91378SJan Blunck S_ISDIR(nd->path.dentry->d_inode->i_mode)) { 109309da5916SJan Blunck struct path old_path = nd->path; 10941da177e4SLinus Torvalds struct qstr last = nd->last; 10951da177e4SLinus Torvalds int last_type = nd->last_type; 1096e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 1097e518ddb7SAndreas Mohr 10981da177e4SLinus Torvalds /* 1099e518ddb7SAndreas Mohr * NAME was not found in alternate root or it's a directory. 1100e518ddb7SAndreas Mohr * Try to find it in the normal root: 11011da177e4SLinus Torvalds */ 11021da177e4SLinus Torvalds nd->last_type = LAST_ROOT; 1103e518ddb7SAndreas Mohr read_lock(&fs->lock); 11046ac08c39SJan Blunck nd->path = fs->root; 11056ac08c39SJan Blunck path_get(&fs->root); 1106e518ddb7SAndreas Mohr read_unlock(&fs->lock); 11071da177e4SLinus Torvalds if (path_walk(name, nd) == 0) { 11084ac91378SJan Blunck if (nd->path.dentry->d_inode) { 110909da5916SJan Blunck path_put(&old_path); 11101da177e4SLinus Torvalds return 1; 11111da177e4SLinus Torvalds } 11121d957f9bSJan Blunck path_put(&nd->path); 11131da177e4SLinus Torvalds } 111409da5916SJan Blunck nd->path = old_path; 11151da177e4SLinus Torvalds nd->last = last; 11161da177e4SLinus Torvalds nd->last_type = last_type; 11171da177e4SLinus Torvalds } 11181da177e4SLinus Torvalds return 1; 11191da177e4SLinus Torvalds } 11201da177e4SLinus Torvalds 11211da177e4SLinus Torvalds void set_fs_altroot(void) 11221da177e4SLinus Torvalds { 11231da177e4SLinus Torvalds char *emul = __emul_prefix(); 11241da177e4SLinus Torvalds struct nameidata nd; 11256ac08c39SJan Blunck struct path path = {}, old_path; 11261da177e4SLinus Torvalds int err; 1127e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 11281da177e4SLinus Torvalds 11291da177e4SLinus Torvalds if (!emul) 11301da177e4SLinus Torvalds goto set_it; 11311da177e4SLinus Torvalds err = path_lookup(emul, LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_NOALT, &nd); 11326ac08c39SJan Blunck if (!err) 11336ac08c39SJan Blunck path = nd.path; 11341da177e4SLinus Torvalds set_it: 1135e518ddb7SAndreas Mohr write_lock(&fs->lock); 11366ac08c39SJan Blunck old_path = fs->altroot; 11376ac08c39SJan Blunck fs->altroot = path; 1138e518ddb7SAndreas Mohr write_unlock(&fs->lock); 11396ac08c39SJan Blunck if (old_path.dentry) 11406ac08c39SJan Blunck path_put(&old_path); 11411da177e4SLinus Torvalds } 11421da177e4SLinus Torvalds 1143ea3834d9SPrasanna Meda /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1144fc9b52cdSHarvey Harrison static int do_path_lookup(int dfd, const char *name, 11455590ff0dSUlrich Drepper unsigned int flags, struct nameidata *nd) 11461da177e4SLinus Torvalds { 1147ea3834d9SPrasanna Meda int retval = 0; 1148170aa3d0SUlrich Drepper int fput_needed; 1149170aa3d0SUlrich Drepper struct file *file; 1150e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 11511da177e4SLinus Torvalds 11521da177e4SLinus Torvalds nd->last_type = LAST_ROOT; /* if there are only slashes... */ 11531da177e4SLinus Torvalds nd->flags = flags; 11541da177e4SLinus Torvalds nd->depth = 0; 11551da177e4SLinus Torvalds 11561da177e4SLinus Torvalds if (*name=='/') { 1157e518ddb7SAndreas Mohr read_lock(&fs->lock); 11586ac08c39SJan Blunck if (fs->altroot.dentry && !(nd->flags & LOOKUP_NOALT)) { 11596ac08c39SJan Blunck nd->path = fs->altroot; 11606ac08c39SJan Blunck path_get(&fs->altroot); 1161e518ddb7SAndreas Mohr read_unlock(&fs->lock); 11621da177e4SLinus Torvalds if (__emul_lookup_dentry(name,nd)) 1163ea3834d9SPrasanna Meda goto out; /* found in altroot */ 1164e518ddb7SAndreas Mohr read_lock(&fs->lock); 11651da177e4SLinus Torvalds } 11666ac08c39SJan Blunck nd->path = fs->root; 11676ac08c39SJan Blunck path_get(&fs->root); 1168e518ddb7SAndreas Mohr read_unlock(&fs->lock); 11695590ff0dSUlrich Drepper } else if (dfd == AT_FDCWD) { 1170e518ddb7SAndreas Mohr read_lock(&fs->lock); 11716ac08c39SJan Blunck nd->path = fs->pwd; 11726ac08c39SJan Blunck path_get(&fs->pwd); 1173e518ddb7SAndreas Mohr read_unlock(&fs->lock); 11745590ff0dSUlrich Drepper } else { 11755590ff0dSUlrich Drepper struct dentry *dentry; 11765590ff0dSUlrich Drepper 11775590ff0dSUlrich Drepper file = fget_light(dfd, &fput_needed); 11785590ff0dSUlrich Drepper retval = -EBADF; 1179170aa3d0SUlrich Drepper if (!file) 11806d09bb62STrond Myklebust goto out_fail; 11815590ff0dSUlrich Drepper 11820f7fc9e4SJosef "Jeff" Sipek dentry = file->f_path.dentry; 11835590ff0dSUlrich Drepper 11845590ff0dSUlrich Drepper retval = -ENOTDIR; 1185170aa3d0SUlrich Drepper if (!S_ISDIR(dentry->d_inode->i_mode)) 11866d09bb62STrond Myklebust goto fput_fail; 11875590ff0dSUlrich Drepper 11885590ff0dSUlrich Drepper retval = file_permission(file, MAY_EXEC); 1189170aa3d0SUlrich Drepper if (retval) 11906d09bb62STrond Myklebust goto fput_fail; 11915590ff0dSUlrich Drepper 11925dd784d0SJan Blunck nd->path = file->f_path; 11935dd784d0SJan Blunck path_get(&file->f_path); 11945590ff0dSUlrich Drepper 11955590ff0dSUlrich Drepper fput_light(file, fput_needed); 11961da177e4SLinus Torvalds } 11972dfdd266SJosef 'Jeff' Sipek 11982dfdd266SJosef 'Jeff' Sipek retval = path_walk(name, nd); 1199ea3834d9SPrasanna Meda out: 12004ac91378SJan Blunck if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && 12014ac91378SJan Blunck nd->path.dentry->d_inode)) 12024ac91378SJan Blunck audit_inode(name, nd->path.dentry); 12036d09bb62STrond Myklebust out_fail: 1204170aa3d0SUlrich Drepper return retval; 1205170aa3d0SUlrich Drepper 12066d09bb62STrond Myklebust fput_fail: 1207170aa3d0SUlrich Drepper fput_light(file, fput_needed); 12086d09bb62STrond Myklebust goto out_fail; 12091da177e4SLinus Torvalds } 12101da177e4SLinus Torvalds 1211fc9b52cdSHarvey Harrison int path_lookup(const char *name, unsigned int flags, 12125590ff0dSUlrich Drepper struct nameidata *nd) 12135590ff0dSUlrich Drepper { 12145590ff0dSUlrich Drepper return do_path_lookup(AT_FDCWD, name, flags, nd); 12155590ff0dSUlrich Drepper } 12165590ff0dSUlrich Drepper 121716f18200SJosef 'Jeff' Sipek /** 121816f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 121916f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 122016f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 122116f18200SJosef 'Jeff' Sipek * @name: pointer to file name 122216f18200SJosef 'Jeff' Sipek * @flags: lookup flags 122316f18200SJosef 'Jeff' Sipek * @nd: pointer to nameidata 122416f18200SJosef 'Jeff' Sipek */ 122516f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 122616f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 122716f18200SJosef 'Jeff' Sipek struct nameidata *nd) 122816f18200SJosef 'Jeff' Sipek { 122916f18200SJosef 'Jeff' Sipek int retval; 123016f18200SJosef 'Jeff' Sipek 123116f18200SJosef 'Jeff' Sipek /* same as do_path_lookup */ 123216f18200SJosef 'Jeff' Sipek nd->last_type = LAST_ROOT; 123316f18200SJosef 'Jeff' Sipek nd->flags = flags; 123416f18200SJosef 'Jeff' Sipek nd->depth = 0; 123516f18200SJosef 'Jeff' Sipek 1236c8e7f449SJan Blunck nd->path.dentry = dentry; 1237c8e7f449SJan Blunck nd->path.mnt = mnt; 1238c8e7f449SJan Blunck path_get(&nd->path); 123916f18200SJosef 'Jeff' Sipek 124016f18200SJosef 'Jeff' Sipek retval = path_walk(name, nd); 12414ac91378SJan Blunck if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && 12424ac91378SJan Blunck nd->path.dentry->d_inode)) 12434ac91378SJan Blunck audit_inode(name, nd->path.dentry); 124416f18200SJosef 'Jeff' Sipek 124516f18200SJosef 'Jeff' Sipek return retval; 124616f18200SJosef 'Jeff' Sipek 124716f18200SJosef 'Jeff' Sipek } 124816f18200SJosef 'Jeff' Sipek 12495590ff0dSUlrich Drepper static int __path_lookup_intent_open(int dfd, const char *name, 12505590ff0dSUlrich Drepper unsigned int lookup_flags, struct nameidata *nd, 12515590ff0dSUlrich Drepper int open_flags, int create_mode) 1252834f2a4aSTrond Myklebust { 1253834f2a4aSTrond Myklebust struct file *filp = get_empty_filp(); 1254834f2a4aSTrond Myklebust int err; 1255834f2a4aSTrond Myklebust 1256834f2a4aSTrond Myklebust if (filp == NULL) 1257834f2a4aSTrond Myklebust return -ENFILE; 1258834f2a4aSTrond Myklebust nd->intent.open.file = filp; 1259834f2a4aSTrond Myklebust nd->intent.open.flags = open_flags; 1260834f2a4aSTrond Myklebust nd->intent.open.create_mode = create_mode; 12615590ff0dSUlrich Drepper err = do_path_lookup(dfd, name, lookup_flags|LOOKUP_OPEN, nd); 1262834f2a4aSTrond Myklebust if (IS_ERR(nd->intent.open.file)) { 1263834f2a4aSTrond Myklebust if (err == 0) { 1264834f2a4aSTrond Myklebust err = PTR_ERR(nd->intent.open.file); 12651d957f9bSJan Blunck path_put(&nd->path); 1266834f2a4aSTrond Myklebust } 1267834f2a4aSTrond Myklebust } else if (err != 0) 1268834f2a4aSTrond Myklebust release_open_intent(nd); 1269834f2a4aSTrond Myklebust return err; 1270834f2a4aSTrond Myklebust } 1271834f2a4aSTrond Myklebust 1272834f2a4aSTrond Myklebust /** 1273834f2a4aSTrond Myklebust * path_lookup_open - lookup a file path with open intent 12747045f37bSMartin Waitz * @dfd: the directory to use as base, or AT_FDCWD 1275834f2a4aSTrond Myklebust * @name: pointer to file name 1276834f2a4aSTrond Myklebust * @lookup_flags: lookup intent flags 1277834f2a4aSTrond Myklebust * @nd: pointer to nameidata 1278834f2a4aSTrond Myklebust * @open_flags: open intent flags 1279834f2a4aSTrond Myklebust */ 12805590ff0dSUlrich Drepper int path_lookup_open(int dfd, const char *name, unsigned int lookup_flags, 1281834f2a4aSTrond Myklebust struct nameidata *nd, int open_flags) 1282834f2a4aSTrond Myklebust { 12835590ff0dSUlrich Drepper return __path_lookup_intent_open(dfd, name, lookup_flags, nd, 1284834f2a4aSTrond Myklebust open_flags, 0); 1285834f2a4aSTrond Myklebust } 1286834f2a4aSTrond Myklebust 1287834f2a4aSTrond Myklebust /** 1288834f2a4aSTrond Myklebust * path_lookup_create - lookup a file path with open + create intent 12897045f37bSMartin Waitz * @dfd: the directory to use as base, or AT_FDCWD 1290834f2a4aSTrond Myklebust * @name: pointer to file name 1291834f2a4aSTrond Myklebust * @lookup_flags: lookup intent flags 1292834f2a4aSTrond Myklebust * @nd: pointer to nameidata 1293834f2a4aSTrond Myklebust * @open_flags: open intent flags 1294834f2a4aSTrond Myklebust * @create_mode: create intent flags 1295834f2a4aSTrond Myklebust */ 12965590ff0dSUlrich Drepper static int path_lookup_create(int dfd, const char *name, 12975590ff0dSUlrich Drepper unsigned int lookup_flags, struct nameidata *nd, 12985590ff0dSUlrich Drepper int open_flags, int create_mode) 1299834f2a4aSTrond Myklebust { 13005590ff0dSUlrich Drepper return __path_lookup_intent_open(dfd, name, lookup_flags|LOOKUP_CREATE, 13015590ff0dSUlrich Drepper nd, open_flags, create_mode); 1302834f2a4aSTrond Myklebust } 1303834f2a4aSTrond Myklebust 1304834f2a4aSTrond Myklebust int __user_path_lookup_open(const char __user *name, unsigned int lookup_flags, 1305834f2a4aSTrond Myklebust struct nameidata *nd, int open_flags) 1306834f2a4aSTrond Myklebust { 1307834f2a4aSTrond Myklebust char *tmp = getname(name); 1308834f2a4aSTrond Myklebust int err = PTR_ERR(tmp); 1309834f2a4aSTrond Myklebust 1310834f2a4aSTrond Myklebust if (!IS_ERR(tmp)) { 13115590ff0dSUlrich Drepper err = __path_lookup_intent_open(AT_FDCWD, tmp, lookup_flags, nd, open_flags, 0); 1312834f2a4aSTrond Myklebust putname(tmp); 1313834f2a4aSTrond Myklebust } 1314834f2a4aSTrond Myklebust return err; 1315834f2a4aSTrond Myklebust } 1316834f2a4aSTrond Myklebust 1317eead1911SChristoph Hellwig static struct dentry *__lookup_hash(struct qstr *name, 1318eead1911SChristoph Hellwig struct dentry *base, struct nameidata *nd) 13191da177e4SLinus Torvalds { 13201da177e4SLinus Torvalds struct dentry *dentry; 13211da177e4SLinus Torvalds struct inode *inode; 13221da177e4SLinus Torvalds int err; 13231da177e4SLinus Torvalds 13241da177e4SLinus Torvalds inode = base->d_inode; 13251da177e4SLinus Torvalds 13261da177e4SLinus Torvalds /* 13271da177e4SLinus Torvalds * See if the low-level filesystem might want 13281da177e4SLinus Torvalds * to use its own hash.. 13291da177e4SLinus Torvalds */ 13301da177e4SLinus Torvalds if (base->d_op && base->d_op->d_hash) { 13311da177e4SLinus Torvalds err = base->d_op->d_hash(base, name); 13321da177e4SLinus Torvalds dentry = ERR_PTR(err); 13331da177e4SLinus Torvalds if (err < 0) 13341da177e4SLinus Torvalds goto out; 13351da177e4SLinus Torvalds } 13361da177e4SLinus Torvalds 13371da177e4SLinus Torvalds dentry = cached_lookup(base, name, nd); 13381da177e4SLinus Torvalds if (!dentry) { 1339d70b67c8SMiklos Szeredi struct dentry *new; 1340d70b67c8SMiklos Szeredi 1341d70b67c8SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 1342d70b67c8SMiklos Szeredi dentry = ERR_PTR(-ENOENT); 1343d70b67c8SMiklos Szeredi if (IS_DEADDIR(inode)) 1344d70b67c8SMiklos Szeredi goto out; 1345d70b67c8SMiklos Szeredi 1346d70b67c8SMiklos Szeredi new = d_alloc(base, name); 13471da177e4SLinus Torvalds dentry = ERR_PTR(-ENOMEM); 13481da177e4SLinus Torvalds if (!new) 13491da177e4SLinus Torvalds goto out; 13501da177e4SLinus Torvalds dentry = inode->i_op->lookup(inode, new, nd); 13511da177e4SLinus Torvalds if (!dentry) 13521da177e4SLinus Torvalds dentry = new; 13531da177e4SLinus Torvalds else 13541da177e4SLinus Torvalds dput(new); 13551da177e4SLinus Torvalds } 13561da177e4SLinus Torvalds out: 13571da177e4SLinus Torvalds return dentry; 13581da177e4SLinus Torvalds } 13591da177e4SLinus Torvalds 1360057f6c01SJames Morris /* 1361057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1362057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1363057f6c01SJames Morris * SMP-safe. 1364057f6c01SJames Morris */ 1365a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 13661da177e4SLinus Torvalds { 1367eead1911SChristoph Hellwig int err; 1368eead1911SChristoph Hellwig 13694ac91378SJan Blunck err = permission(nd->path.dentry->d_inode, MAY_EXEC, nd); 1370eead1911SChristoph Hellwig if (err) 1371eead1911SChristoph Hellwig return ERR_PTR(err); 13724ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 13731da177e4SLinus Torvalds } 13741da177e4SLinus Torvalds 1375eead1911SChristoph Hellwig static int __lookup_one_len(const char *name, struct qstr *this, 1376eead1911SChristoph Hellwig struct dentry *base, int len) 13771da177e4SLinus Torvalds { 13781da177e4SLinus Torvalds unsigned long hash; 13791da177e4SLinus Torvalds unsigned int c; 13801da177e4SLinus Torvalds 1381057f6c01SJames Morris this->name = name; 1382057f6c01SJames Morris this->len = len; 13831da177e4SLinus Torvalds if (!len) 1384057f6c01SJames Morris return -EACCES; 13851da177e4SLinus Torvalds 13861da177e4SLinus Torvalds hash = init_name_hash(); 13871da177e4SLinus Torvalds while (len--) { 13881da177e4SLinus Torvalds c = *(const unsigned char *)name++; 13891da177e4SLinus Torvalds if (c == '/' || c == '\0') 1390057f6c01SJames Morris return -EACCES; 13911da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 13921da177e4SLinus Torvalds } 1393057f6c01SJames Morris this->hash = end_name_hash(hash); 1394057f6c01SJames Morris return 0; 1395057f6c01SJames Morris } 13961da177e4SLinus Torvalds 1397eead1911SChristoph Hellwig /** 1398a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1399eead1911SChristoph Hellwig * @name: pathname component to lookup 1400eead1911SChristoph Hellwig * @base: base directory to lookup from 1401eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1402eead1911SChristoph Hellwig * 1403a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1404a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1405eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1406eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1407eead1911SChristoph Hellwig */ 1408057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1409057f6c01SJames Morris { 1410057f6c01SJames Morris int err; 1411057f6c01SJames Morris struct qstr this; 1412057f6c01SJames Morris 1413057f6c01SJames Morris err = __lookup_one_len(name, &this, base, len); 1414057f6c01SJames Morris if (err) 1415057f6c01SJames Morris return ERR_PTR(err); 1416eead1911SChristoph Hellwig 1417eead1911SChristoph Hellwig err = permission(base->d_inode, MAY_EXEC, NULL); 1418eead1911SChristoph Hellwig if (err) 1419eead1911SChristoph Hellwig return ERR_PTR(err); 142049705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1421057f6c01SJames Morris } 1422057f6c01SJames Morris 1423eead1911SChristoph Hellwig /** 1424eead1911SChristoph Hellwig * lookup_one_noperm - bad hack for sysfs 1425eead1911SChristoph Hellwig * @name: pathname component to lookup 1426eead1911SChristoph Hellwig * @base: base directory to lookup from 1427eead1911SChristoph Hellwig * 1428eead1911SChristoph Hellwig * This is a variant of lookup_one_len that doesn't perform any permission 1429eead1911SChristoph Hellwig * checks. It's a horrible hack to work around the braindead sysfs 1430eead1911SChristoph Hellwig * architecture and should not be used anywhere else. 1431eead1911SChristoph Hellwig * 1432eead1911SChristoph Hellwig * DON'T USE THIS FUNCTION EVER, thanks. 1433eead1911SChristoph Hellwig */ 1434eead1911SChristoph Hellwig struct dentry *lookup_one_noperm(const char *name, struct dentry *base) 1435057f6c01SJames Morris { 1436057f6c01SJames Morris int err; 1437057f6c01SJames Morris struct qstr this; 1438057f6c01SJames Morris 1439eead1911SChristoph Hellwig err = __lookup_one_len(name, &this, base, strlen(name)); 1440057f6c01SJames Morris if (err) 1441057f6c01SJames Morris return ERR_PTR(err); 1442eead1911SChristoph Hellwig return __lookup_hash(&this, base, NULL); 14431da177e4SLinus Torvalds } 14441da177e4SLinus Torvalds 1445fc9b52cdSHarvey Harrison int __user_walk_fd(int dfd, const char __user *name, unsigned flags, 14465590ff0dSUlrich Drepper struct nameidata *nd) 14471da177e4SLinus Torvalds { 14481da177e4SLinus Torvalds char *tmp = getname(name); 14491da177e4SLinus Torvalds int err = PTR_ERR(tmp); 14501da177e4SLinus Torvalds 14511da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 14525590ff0dSUlrich Drepper err = do_path_lookup(dfd, tmp, flags, nd); 14531da177e4SLinus Torvalds putname(tmp); 14541da177e4SLinus Torvalds } 14551da177e4SLinus Torvalds return err; 14561da177e4SLinus Torvalds } 14571da177e4SLinus Torvalds 1458fc9b52cdSHarvey Harrison int __user_walk(const char __user *name, unsigned flags, struct nameidata *nd) 14595590ff0dSUlrich Drepper { 14605590ff0dSUlrich Drepper return __user_walk_fd(AT_FDCWD, name, flags, nd); 14615590ff0dSUlrich Drepper } 14625590ff0dSUlrich Drepper 14631da177e4SLinus Torvalds /* 14641da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 14651da177e4SLinus Torvalds * minimal. 14661da177e4SLinus Torvalds */ 14671da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 14681da177e4SLinus Torvalds { 14691da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 14701da177e4SLinus Torvalds return 0; 14711da177e4SLinus Torvalds if (inode->i_uid == current->fsuid) 14721da177e4SLinus Torvalds return 0; 14731da177e4SLinus Torvalds if (dir->i_uid == current->fsuid) 14741da177e4SLinus Torvalds return 0; 14751da177e4SLinus Torvalds return !capable(CAP_FOWNER); 14761da177e4SLinus Torvalds } 14771da177e4SLinus Torvalds 14781da177e4SLinus Torvalds /* 14791da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 14801da177e4SLinus Torvalds * whether the type of victim is right. 14811da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 14821da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 14831da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 14841da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 14851da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 14861da177e4SLinus Torvalds * a. be owner of dir, or 14871da177e4SLinus Torvalds * b. be owner of victim, or 14881da177e4SLinus Torvalds * c. have CAP_FOWNER capability 14891da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 14901da177e4SLinus Torvalds * links pointing to it. 14911da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 14921da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 14931da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 14941da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 14951da177e4SLinus Torvalds * nfs_async_unlink(). 14961da177e4SLinus Torvalds */ 1497858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 14981da177e4SLinus Torvalds { 14991da177e4SLinus Torvalds int error; 15001da177e4SLinus Torvalds 15011da177e4SLinus Torvalds if (!victim->d_inode) 15021da177e4SLinus Torvalds return -ENOENT; 15031da177e4SLinus Torvalds 15041da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 15055a190ae6SAl Viro audit_inode_child(victim->d_name.name, victim, dir); 15061da177e4SLinus Torvalds 15071da177e4SLinus Torvalds error = permission(dir,MAY_WRITE | MAY_EXEC, NULL); 15081da177e4SLinus Torvalds if (error) 15091da177e4SLinus Torvalds return error; 15101da177e4SLinus Torvalds if (IS_APPEND(dir)) 15111da177e4SLinus Torvalds return -EPERM; 15121da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 15131da177e4SLinus Torvalds IS_IMMUTABLE(victim->d_inode)) 15141da177e4SLinus Torvalds return -EPERM; 15151da177e4SLinus Torvalds if (isdir) { 15161da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 15171da177e4SLinus Torvalds return -ENOTDIR; 15181da177e4SLinus Torvalds if (IS_ROOT(victim)) 15191da177e4SLinus Torvalds return -EBUSY; 15201da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 15211da177e4SLinus Torvalds return -EISDIR; 15221da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 15231da177e4SLinus Torvalds return -ENOENT; 15241da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 15251da177e4SLinus Torvalds return -EBUSY; 15261da177e4SLinus Torvalds return 0; 15271da177e4SLinus Torvalds } 15281da177e4SLinus Torvalds 15291da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 15301da177e4SLinus Torvalds * dir. 15311da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 15321da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 15331da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 15341da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 15351da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 15361da177e4SLinus Torvalds */ 15371da177e4SLinus Torvalds static inline int may_create(struct inode *dir, struct dentry *child, 15381da177e4SLinus Torvalds struct nameidata *nd) 15391da177e4SLinus Torvalds { 15401da177e4SLinus Torvalds if (child->d_inode) 15411da177e4SLinus Torvalds return -EEXIST; 15421da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 15431da177e4SLinus Torvalds return -ENOENT; 15441da177e4SLinus Torvalds return permission(dir,MAY_WRITE | MAY_EXEC, nd); 15451da177e4SLinus Torvalds } 15461da177e4SLinus Torvalds 15471da177e4SLinus Torvalds /* 15481da177e4SLinus Torvalds * O_DIRECTORY translates into forcing a directory lookup. 15491da177e4SLinus Torvalds */ 15501da177e4SLinus Torvalds static inline int lookup_flags(unsigned int f) 15511da177e4SLinus Torvalds { 15521da177e4SLinus Torvalds unsigned long retval = LOOKUP_FOLLOW; 15531da177e4SLinus Torvalds 15541da177e4SLinus Torvalds if (f & O_NOFOLLOW) 15551da177e4SLinus Torvalds retval &= ~LOOKUP_FOLLOW; 15561da177e4SLinus Torvalds 15571da177e4SLinus Torvalds if (f & O_DIRECTORY) 15581da177e4SLinus Torvalds retval |= LOOKUP_DIRECTORY; 15591da177e4SLinus Torvalds 15601da177e4SLinus Torvalds return retval; 15611da177e4SLinus Torvalds } 15621da177e4SLinus Torvalds 15631da177e4SLinus Torvalds /* 15641da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 15651da177e4SLinus Torvalds */ 15661da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 15671da177e4SLinus Torvalds { 15681da177e4SLinus Torvalds struct dentry *p; 15691da177e4SLinus Torvalds 15701da177e4SLinus Torvalds if (p1 == p2) { 1571f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 15721da177e4SLinus Torvalds return NULL; 15731da177e4SLinus Torvalds } 15741da177e4SLinus Torvalds 1575a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 15761da177e4SLinus Torvalds 15771da177e4SLinus Torvalds for (p = p1; p->d_parent != p; p = p->d_parent) { 15781da177e4SLinus Torvalds if (p->d_parent == p2) { 1579f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 1580f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 15811da177e4SLinus Torvalds return p; 15821da177e4SLinus Torvalds } 15831da177e4SLinus Torvalds } 15841da177e4SLinus Torvalds 15851da177e4SLinus Torvalds for (p = p2; p->d_parent != p; p = p->d_parent) { 15861da177e4SLinus Torvalds if (p->d_parent == p1) { 1587f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1588f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 15891da177e4SLinus Torvalds return p; 15901da177e4SLinus Torvalds } 15911da177e4SLinus Torvalds } 15921da177e4SLinus Torvalds 1593f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1594f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 15951da177e4SLinus Torvalds return NULL; 15961da177e4SLinus Torvalds } 15971da177e4SLinus Torvalds 15981da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 15991da177e4SLinus Torvalds { 16001b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 16011da177e4SLinus Torvalds if (p1 != p2) { 16021b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 1603a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 16041da177e4SLinus Torvalds } 16051da177e4SLinus Torvalds } 16061da177e4SLinus Torvalds 16071da177e4SLinus Torvalds int vfs_create(struct inode *dir, struct dentry *dentry, int mode, 16081da177e4SLinus Torvalds struct nameidata *nd) 16091da177e4SLinus Torvalds { 16101da177e4SLinus Torvalds int error = may_create(dir, dentry, nd); 16111da177e4SLinus Torvalds 16121da177e4SLinus Torvalds if (error) 16131da177e4SLinus Torvalds return error; 16141da177e4SLinus Torvalds 16151da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->create) 16161da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 16171da177e4SLinus Torvalds mode &= S_IALLUGO; 16181da177e4SLinus Torvalds mode |= S_IFREG; 16191da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 16201da177e4SLinus Torvalds if (error) 16211da177e4SLinus Torvalds return error; 16221da177e4SLinus Torvalds DQUOT_INIT(dir); 16231da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 1624a74574aaSStephen Smalley if (!error) 1625f38aa942SAmy Griffis fsnotify_create(dir, dentry); 16261da177e4SLinus Torvalds return error; 16271da177e4SLinus Torvalds } 16281da177e4SLinus Torvalds 16291da177e4SLinus Torvalds int may_open(struct nameidata *nd, int acc_mode, int flag) 16301da177e4SLinus Torvalds { 16314ac91378SJan Blunck struct dentry *dentry = nd->path.dentry; 16321da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 16331da177e4SLinus Torvalds int error; 16341da177e4SLinus Torvalds 16351da177e4SLinus Torvalds if (!inode) 16361da177e4SLinus Torvalds return -ENOENT; 16371da177e4SLinus Torvalds 16381da177e4SLinus Torvalds if (S_ISLNK(inode->i_mode)) 16391da177e4SLinus Torvalds return -ELOOP; 16401da177e4SLinus Torvalds 1641974a9f0bSLinus Torvalds if (S_ISDIR(inode->i_mode) && (acc_mode & MAY_WRITE)) 16421da177e4SLinus Torvalds return -EISDIR; 16431da177e4SLinus Torvalds 16441da177e4SLinus Torvalds /* 16451da177e4SLinus Torvalds * FIFO's, sockets and device files are special: they don't 16461da177e4SLinus Torvalds * actually live on the filesystem itself, and as such you 16471da177e4SLinus Torvalds * can write to them even if the filesystem is read-only. 16481da177e4SLinus Torvalds */ 16491da177e4SLinus Torvalds if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) { 16501da177e4SLinus Torvalds flag &= ~O_TRUNC; 16511da177e4SLinus Torvalds } else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) { 16524ac91378SJan Blunck if (nd->path.mnt->mnt_flags & MNT_NODEV) 16531da177e4SLinus Torvalds return -EACCES; 16541da177e4SLinus Torvalds 16551da177e4SLinus Torvalds flag &= ~O_TRUNC; 16564a3fd211SDave Hansen } 1657b41572e9SDave Hansen 1658b41572e9SDave Hansen error = vfs_permission(nd, acc_mode); 1659b41572e9SDave Hansen if (error) 1660b41572e9SDave Hansen return error; 16611da177e4SLinus Torvalds /* 16621da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 16631da177e4SLinus Torvalds */ 16641da177e4SLinus Torvalds if (IS_APPEND(inode)) { 16651da177e4SLinus Torvalds if ((flag & FMODE_WRITE) && !(flag & O_APPEND)) 16661da177e4SLinus Torvalds return -EPERM; 16671da177e4SLinus Torvalds if (flag & O_TRUNC) 16681da177e4SLinus Torvalds return -EPERM; 16691da177e4SLinus Torvalds } 16701da177e4SLinus Torvalds 16711da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 16721da177e4SLinus Torvalds if (flag & O_NOATIME) 16733bd858abSSatyam Sharma if (!is_owner_or_cap(inode)) 16741da177e4SLinus Torvalds return -EPERM; 16751da177e4SLinus Torvalds 16761da177e4SLinus Torvalds /* 16771da177e4SLinus Torvalds * Ensure there are no outstanding leases on the file. 16781da177e4SLinus Torvalds */ 16791da177e4SLinus Torvalds error = break_lease(inode, flag); 16801da177e4SLinus Torvalds if (error) 16811da177e4SLinus Torvalds return error; 16821da177e4SLinus Torvalds 16831da177e4SLinus Torvalds if (flag & O_TRUNC) { 16841da177e4SLinus Torvalds error = get_write_access(inode); 16851da177e4SLinus Torvalds if (error) 16861da177e4SLinus Torvalds return error; 16871da177e4SLinus Torvalds 16881da177e4SLinus Torvalds /* 16891da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 16901da177e4SLinus Torvalds */ 16911da177e4SLinus Torvalds error = locks_verify_locked(inode); 16921da177e4SLinus Torvalds if (!error) { 16931da177e4SLinus Torvalds DQUOT_INIT(inode); 16941da177e4SLinus Torvalds 1695d139d7ffSMiklos Szeredi error = do_truncate(dentry, 0, 1696d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 1697d139d7ffSMiklos Szeredi NULL); 16981da177e4SLinus Torvalds } 16991da177e4SLinus Torvalds put_write_access(inode); 17001da177e4SLinus Torvalds if (error) 17011da177e4SLinus Torvalds return error; 17021da177e4SLinus Torvalds } else 17031da177e4SLinus Torvalds if (flag & FMODE_WRITE) 17041da177e4SLinus Torvalds DQUOT_INIT(inode); 17051da177e4SLinus Torvalds 17061da177e4SLinus Torvalds return 0; 17071da177e4SLinus Torvalds } 17081da177e4SLinus Torvalds 1709d57999e1SDave Hansen /* 1710d57999e1SDave Hansen * Be careful about ever adding any more callers of this 1711d57999e1SDave Hansen * function. Its flags must be in the namei format, not 1712d57999e1SDave Hansen * what get passed to sys_open(). 1713d57999e1SDave Hansen */ 1714d57999e1SDave Hansen static int __open_namei_create(struct nameidata *nd, struct path *path, 1715aab520e2SDave Hansen int flag, int mode) 1716aab520e2SDave Hansen { 1717aab520e2SDave Hansen int error; 17184ac91378SJan Blunck struct dentry *dir = nd->path.dentry; 1719aab520e2SDave Hansen 1720aab520e2SDave Hansen if (!IS_POSIXACL(dir->d_inode)) 1721aab520e2SDave Hansen mode &= ~current->fs->umask; 1722aab520e2SDave Hansen error = vfs_create(dir->d_inode, path->dentry, mode, nd); 1723aab520e2SDave Hansen mutex_unlock(&dir->d_inode->i_mutex); 17244ac91378SJan Blunck dput(nd->path.dentry); 17254ac91378SJan Blunck nd->path.dentry = path->dentry; 1726aab520e2SDave Hansen if (error) 1727aab520e2SDave Hansen return error; 1728aab520e2SDave Hansen /* Don't check for write permission, don't truncate */ 1729aab520e2SDave Hansen return may_open(nd, 0, flag & ~O_TRUNC); 1730aab520e2SDave Hansen } 1731aab520e2SDave Hansen 17321da177e4SLinus Torvalds /* 1733d57999e1SDave Hansen * Note that while the flag value (low two bits) for sys_open means: 1734d57999e1SDave Hansen * 00 - read-only 1735d57999e1SDave Hansen * 01 - write-only 1736d57999e1SDave Hansen * 10 - read-write 1737d57999e1SDave Hansen * 11 - special 1738d57999e1SDave Hansen * it is changed into 1739d57999e1SDave Hansen * 00 - no permissions needed 1740d57999e1SDave Hansen * 01 - read-permission 1741d57999e1SDave Hansen * 10 - write-permission 1742d57999e1SDave Hansen * 11 - read-write 1743d57999e1SDave Hansen * for the internal routines (ie open_namei()/follow_link() etc) 1744d57999e1SDave Hansen * This is more logical, and also allows the 00 "no perm needed" 1745d57999e1SDave Hansen * to be used for symlinks (where the permissions are checked 1746d57999e1SDave Hansen * later). 1747d57999e1SDave Hansen * 1748d57999e1SDave Hansen */ 1749d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 1750d57999e1SDave Hansen { 1751d57999e1SDave Hansen if ((flag+1) & O_ACCMODE) 1752d57999e1SDave Hansen flag++; 1753d57999e1SDave Hansen return flag; 1754d57999e1SDave Hansen } 1755d57999e1SDave Hansen 17564a3fd211SDave Hansen static int open_will_write_to_fs(int flag, struct inode *inode) 17574a3fd211SDave Hansen { 1758d57999e1SDave Hansen /* 17594a3fd211SDave Hansen * We'll never write to the fs underlying 17604a3fd211SDave Hansen * a device file. 17614a3fd211SDave Hansen */ 17624a3fd211SDave Hansen if (special_file(inode->i_mode)) 17634a3fd211SDave Hansen return 0; 17644a3fd211SDave Hansen return (flag & O_TRUNC); 17654a3fd211SDave Hansen } 17664a3fd211SDave Hansen 17674a3fd211SDave Hansen /* 17684a3fd211SDave Hansen * Note that the low bits of the passed in "open_flag" 17694a3fd211SDave Hansen * are not the same as in the local variable "flag". See 17704a3fd211SDave Hansen * open_to_namei_flags() for more details. 17711da177e4SLinus Torvalds */ 1772a70e65dfSChristoph Hellwig struct file *do_filp_open(int dfd, const char *pathname, 1773a70e65dfSChristoph Hellwig int open_flag, int mode) 17741da177e4SLinus Torvalds { 17754a3fd211SDave Hansen struct file *filp; 1776a70e65dfSChristoph Hellwig struct nameidata nd; 1777834f2a4aSTrond Myklebust int acc_mode, error; 17784e7506e4SAl Viro struct path path; 17791da177e4SLinus Torvalds struct dentry *dir; 17801da177e4SLinus Torvalds int count = 0; 17814a3fd211SDave Hansen int will_write; 1782d57999e1SDave Hansen int flag = open_to_namei_flags(open_flag); 17831da177e4SLinus Torvalds 17841da177e4SLinus Torvalds acc_mode = ACC_MODE(flag); 17851da177e4SLinus Torvalds 1786834f2a4aSTrond Myklebust /* O_TRUNC implies we need access checks for write permissions */ 1787834f2a4aSTrond Myklebust if (flag & O_TRUNC) 1788834f2a4aSTrond Myklebust acc_mode |= MAY_WRITE; 1789834f2a4aSTrond Myklebust 17901da177e4SLinus Torvalds /* Allow the LSM permission hook to distinguish append 17911da177e4SLinus Torvalds access from general write access. */ 17921da177e4SLinus Torvalds if (flag & O_APPEND) 17931da177e4SLinus Torvalds acc_mode |= MAY_APPEND; 17941da177e4SLinus Torvalds 17951da177e4SLinus Torvalds /* 17961da177e4SLinus Torvalds * The simplest case - just a plain lookup. 17971da177e4SLinus Torvalds */ 17981da177e4SLinus Torvalds if (!(flag & O_CREAT)) { 17995590ff0dSUlrich Drepper error = path_lookup_open(dfd, pathname, lookup_flags(flag), 1800a70e65dfSChristoph Hellwig &nd, flag); 18011da177e4SLinus Torvalds if (error) 1802a70e65dfSChristoph Hellwig return ERR_PTR(error); 18031da177e4SLinus Torvalds goto ok; 18041da177e4SLinus Torvalds } 18051da177e4SLinus Torvalds 18061da177e4SLinus Torvalds /* 18071da177e4SLinus Torvalds * Create - we need to know the parent. 18081da177e4SLinus Torvalds */ 1809a70e65dfSChristoph Hellwig error = path_lookup_create(dfd, pathname, LOOKUP_PARENT, 1810a70e65dfSChristoph Hellwig &nd, flag, mode); 18111da177e4SLinus Torvalds if (error) 1812a70e65dfSChristoph Hellwig return ERR_PTR(error); 18131da177e4SLinus Torvalds 18141da177e4SLinus Torvalds /* 18151da177e4SLinus Torvalds * We have the parent and last component. First of all, check 18161da177e4SLinus Torvalds * that we are not asked to creat(2) an obvious directory - that 18171da177e4SLinus Torvalds * will not do. 18181da177e4SLinus Torvalds */ 18191da177e4SLinus Torvalds error = -EISDIR; 1820a70e65dfSChristoph Hellwig if (nd.last_type != LAST_NORM || nd.last.name[nd.last.len]) 18211da177e4SLinus Torvalds goto exit; 18221da177e4SLinus Torvalds 1823a70e65dfSChristoph Hellwig dir = nd.path.dentry; 1824a70e65dfSChristoph Hellwig nd.flags &= ~LOOKUP_PARENT; 18251b1dcc1bSJes Sorensen mutex_lock(&dir->d_inode->i_mutex); 1826a70e65dfSChristoph Hellwig path.dentry = lookup_hash(&nd); 1827a70e65dfSChristoph Hellwig path.mnt = nd.path.mnt; 18281da177e4SLinus Torvalds 18291da177e4SLinus Torvalds do_last: 18304e7506e4SAl Viro error = PTR_ERR(path.dentry); 18314e7506e4SAl Viro if (IS_ERR(path.dentry)) { 18321b1dcc1bSJes Sorensen mutex_unlock(&dir->d_inode->i_mutex); 18331da177e4SLinus Torvalds goto exit; 18341da177e4SLinus Torvalds } 18351da177e4SLinus Torvalds 1836a70e65dfSChristoph Hellwig if (IS_ERR(nd.intent.open.file)) { 1837a70e65dfSChristoph Hellwig error = PTR_ERR(nd.intent.open.file); 18384a3fd211SDave Hansen goto exit_mutex_unlock; 18394af4c52fSOleg Drokin } 18404af4c52fSOleg Drokin 18411da177e4SLinus Torvalds /* Negative dentry, just create the file */ 18424e7506e4SAl Viro if (!path.dentry->d_inode) { 18434a3fd211SDave Hansen /* 18444a3fd211SDave Hansen * This write is needed to ensure that a 18454a3fd211SDave Hansen * ro->rw transition does not occur between 18464a3fd211SDave Hansen * the time when the file is created and when 18474a3fd211SDave Hansen * a permanent write count is taken through 18484a3fd211SDave Hansen * the 'struct file' in nameidata_to_filp(). 18494a3fd211SDave Hansen */ 18504a3fd211SDave Hansen error = mnt_want_write(nd.path.mnt); 18511da177e4SLinus Torvalds if (error) 18524a3fd211SDave Hansen goto exit_mutex_unlock; 18534a3fd211SDave Hansen error = __open_namei_create(&nd, &path, flag, mode); 18544a3fd211SDave Hansen if (error) { 18554a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 18561da177e4SLinus Torvalds goto exit; 18574a3fd211SDave Hansen } 18584a3fd211SDave Hansen filp = nameidata_to_filp(&nd, open_flag); 18594a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 18604a3fd211SDave Hansen return filp; 18611da177e4SLinus Torvalds } 18621da177e4SLinus Torvalds 18631da177e4SLinus Torvalds /* 18641da177e4SLinus Torvalds * It already exists. 18651da177e4SLinus Torvalds */ 18661b1dcc1bSJes Sorensen mutex_unlock(&dir->d_inode->i_mutex); 18675a190ae6SAl Viro audit_inode(pathname, path.dentry); 18681da177e4SLinus Torvalds 18691da177e4SLinus Torvalds error = -EEXIST; 18701da177e4SLinus Torvalds if (flag & O_EXCL) 18711da177e4SLinus Torvalds goto exit_dput; 18721da177e4SLinus Torvalds 1873e13b210fSAl Viro if (__follow_mount(&path)) { 18741da177e4SLinus Torvalds error = -ELOOP; 1875ba7a4c1aSAl Viro if (flag & O_NOFOLLOW) 1876ba7a4c1aSAl Viro goto exit_dput; 18771da177e4SLinus Torvalds } 18783e2efce0SAmy Griffis 18791da177e4SLinus Torvalds error = -ENOENT; 18804e7506e4SAl Viro if (!path.dentry->d_inode) 18811da177e4SLinus Torvalds goto exit_dput; 18824e7506e4SAl Viro if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link) 18831da177e4SLinus Torvalds goto do_link; 18841da177e4SLinus Torvalds 1885a70e65dfSChristoph Hellwig path_to_nameidata(&path, &nd); 18861da177e4SLinus Torvalds error = -EISDIR; 18874e7506e4SAl Viro if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode)) 18881da177e4SLinus Torvalds goto exit; 18891da177e4SLinus Torvalds ok: 18904a3fd211SDave Hansen /* 18914a3fd211SDave Hansen * Consider: 18924a3fd211SDave Hansen * 1. may_open() truncates a file 18934a3fd211SDave Hansen * 2. a rw->ro mount transition occurs 18944a3fd211SDave Hansen * 3. nameidata_to_filp() fails due to 18954a3fd211SDave Hansen * the ro mount. 18964a3fd211SDave Hansen * That would be inconsistent, and should 18974a3fd211SDave Hansen * be avoided. Taking this mnt write here 18984a3fd211SDave Hansen * ensures that (2) can not occur. 18994a3fd211SDave Hansen */ 19004a3fd211SDave Hansen will_write = open_will_write_to_fs(flag, nd.path.dentry->d_inode); 19014a3fd211SDave Hansen if (will_write) { 19024a3fd211SDave Hansen error = mnt_want_write(nd.path.mnt); 19031da177e4SLinus Torvalds if (error) 19041da177e4SLinus Torvalds goto exit; 19054a3fd211SDave Hansen } 19064a3fd211SDave Hansen error = may_open(&nd, acc_mode, flag); 19074a3fd211SDave Hansen if (error) { 19084a3fd211SDave Hansen if (will_write) 19094a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 19104a3fd211SDave Hansen goto exit; 19114a3fd211SDave Hansen } 19124a3fd211SDave Hansen filp = nameidata_to_filp(&nd, open_flag); 19134a3fd211SDave Hansen /* 19144a3fd211SDave Hansen * It is now safe to drop the mnt write 19154a3fd211SDave Hansen * because the filp has had a write taken 19164a3fd211SDave Hansen * on its behalf. 19174a3fd211SDave Hansen */ 19184a3fd211SDave Hansen if (will_write) 19194a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 19204a3fd211SDave Hansen return filp; 19211da177e4SLinus Torvalds 19224a3fd211SDave Hansen exit_mutex_unlock: 19234a3fd211SDave Hansen mutex_unlock(&dir->d_inode->i_mutex); 19241da177e4SLinus Torvalds exit_dput: 1925a70e65dfSChristoph Hellwig path_put_conditional(&path, &nd); 19261da177e4SLinus Torvalds exit: 1927a70e65dfSChristoph Hellwig if (!IS_ERR(nd.intent.open.file)) 1928a70e65dfSChristoph Hellwig release_open_intent(&nd); 1929a70e65dfSChristoph Hellwig path_put(&nd.path); 1930a70e65dfSChristoph Hellwig return ERR_PTR(error); 19311da177e4SLinus Torvalds 19321da177e4SLinus Torvalds do_link: 19331da177e4SLinus Torvalds error = -ELOOP; 19341da177e4SLinus Torvalds if (flag & O_NOFOLLOW) 19351da177e4SLinus Torvalds goto exit_dput; 19361da177e4SLinus Torvalds /* 19371da177e4SLinus Torvalds * This is subtle. Instead of calling do_follow_link() we do the 19381da177e4SLinus Torvalds * thing by hands. The reason is that this way we have zero link_count 19391da177e4SLinus Torvalds * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT. 19401da177e4SLinus Torvalds * After that we have the parent and last component, i.e. 19411da177e4SLinus Torvalds * we are in the same situation as after the first path_walk(). 19421da177e4SLinus Torvalds * Well, almost - if the last component is normal we get its copy 19431da177e4SLinus Torvalds * stored in nd->last.name and we will have to putname() it when we 19441da177e4SLinus Torvalds * are done. Procfs-like symlinks just set LAST_BIND. 19451da177e4SLinus Torvalds */ 1946a70e65dfSChristoph Hellwig nd.flags |= LOOKUP_PARENT; 1947a70e65dfSChristoph Hellwig error = security_inode_follow_link(path.dentry, &nd); 19481da177e4SLinus Torvalds if (error) 19491da177e4SLinus Torvalds goto exit_dput; 1950a70e65dfSChristoph Hellwig error = __do_follow_link(&path, &nd); 1951de459215SKirill Korotaev if (error) { 1952de459215SKirill Korotaev /* Does someone understand code flow here? Or it is only 1953de459215SKirill Korotaev * me so stupid? Anathema to whoever designed this non-sense 1954de459215SKirill Korotaev * with "intent.open". 1955de459215SKirill Korotaev */ 1956a70e65dfSChristoph Hellwig release_open_intent(&nd); 1957a70e65dfSChristoph Hellwig return ERR_PTR(error); 1958de459215SKirill Korotaev } 1959a70e65dfSChristoph Hellwig nd.flags &= ~LOOKUP_PARENT; 1960a70e65dfSChristoph Hellwig if (nd.last_type == LAST_BIND) 19611da177e4SLinus Torvalds goto ok; 19621da177e4SLinus Torvalds error = -EISDIR; 1963a70e65dfSChristoph Hellwig if (nd.last_type != LAST_NORM) 19641da177e4SLinus Torvalds goto exit; 1965a70e65dfSChristoph Hellwig if (nd.last.name[nd.last.len]) { 1966a70e65dfSChristoph Hellwig __putname(nd.last.name); 19671da177e4SLinus Torvalds goto exit; 19681da177e4SLinus Torvalds } 19691da177e4SLinus Torvalds error = -ELOOP; 19701da177e4SLinus Torvalds if (count++==32) { 1971a70e65dfSChristoph Hellwig __putname(nd.last.name); 19721da177e4SLinus Torvalds goto exit; 19731da177e4SLinus Torvalds } 1974a70e65dfSChristoph Hellwig dir = nd.path.dentry; 19751b1dcc1bSJes Sorensen mutex_lock(&dir->d_inode->i_mutex); 1976a70e65dfSChristoph Hellwig path.dentry = lookup_hash(&nd); 1977a70e65dfSChristoph Hellwig path.mnt = nd.path.mnt; 1978a70e65dfSChristoph Hellwig __putname(nd.last.name); 19791da177e4SLinus Torvalds goto do_last; 19801da177e4SLinus Torvalds } 19811da177e4SLinus Torvalds 19821da177e4SLinus Torvalds /** 1983a70e65dfSChristoph Hellwig * filp_open - open file and return file pointer 1984a70e65dfSChristoph Hellwig * 1985a70e65dfSChristoph Hellwig * @filename: path to open 1986a70e65dfSChristoph Hellwig * @flags: open flags as per the open(2) second argument 1987a70e65dfSChristoph Hellwig * @mode: mode for the new file if O_CREAT is set, else ignored 1988a70e65dfSChristoph Hellwig * 1989a70e65dfSChristoph Hellwig * This is the helper to open a file from kernelspace if you really 1990a70e65dfSChristoph Hellwig * have to. But in generally you should not do this, so please move 1991a70e65dfSChristoph Hellwig * along, nothing to see here.. 1992a70e65dfSChristoph Hellwig */ 1993a70e65dfSChristoph Hellwig struct file *filp_open(const char *filename, int flags, int mode) 1994a70e65dfSChristoph Hellwig { 1995a70e65dfSChristoph Hellwig return do_filp_open(AT_FDCWD, filename, flags, mode); 1996a70e65dfSChristoph Hellwig } 1997a70e65dfSChristoph Hellwig EXPORT_SYMBOL(filp_open); 1998a70e65dfSChristoph Hellwig 1999a70e65dfSChristoph Hellwig /** 20001da177e4SLinus Torvalds * lookup_create - lookup a dentry, creating it if it doesn't exist 20011da177e4SLinus Torvalds * @nd: nameidata info 20021da177e4SLinus Torvalds * @is_dir: directory flag 20031da177e4SLinus Torvalds * 20041da177e4SLinus Torvalds * Simple function to lookup and return a dentry and create it 20051da177e4SLinus Torvalds * if it doesn't exist. Is SMP-safe. 2006c663e5d8SChristoph Hellwig * 20074ac91378SJan Blunck * Returns with nd->path.dentry->d_inode->i_mutex locked. 20081da177e4SLinus Torvalds */ 20091da177e4SLinus Torvalds struct dentry *lookup_create(struct nameidata *nd, int is_dir) 20101da177e4SLinus Torvalds { 2011c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 20121da177e4SLinus Torvalds 20134ac91378SJan Blunck mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 2014c663e5d8SChristoph Hellwig /* 2015c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 2016c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 2017c663e5d8SChristoph Hellwig */ 20181da177e4SLinus Torvalds if (nd->last_type != LAST_NORM) 20191da177e4SLinus Torvalds goto fail; 20201da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 2021a634904aSASANO Masahiro nd->flags |= LOOKUP_CREATE; 2022a634904aSASANO Masahiro nd->intent.open.flags = O_EXCL; 2023c663e5d8SChristoph Hellwig 2024c663e5d8SChristoph Hellwig /* 2025c663e5d8SChristoph Hellwig * Do the final lookup. 2026c663e5d8SChristoph Hellwig */ 202749705b77SChristoph Hellwig dentry = lookup_hash(nd); 20281da177e4SLinus Torvalds if (IS_ERR(dentry)) 20291da177e4SLinus Torvalds goto fail; 2030c663e5d8SChristoph Hellwig 2031e9baf6e5SAl Viro if (dentry->d_inode) 2032e9baf6e5SAl Viro goto eexist; 2033c663e5d8SChristoph Hellwig /* 2034c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 2035c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 2036c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 2037c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 2038c663e5d8SChristoph Hellwig */ 2039e9baf6e5SAl Viro if (unlikely(!is_dir && nd->last.name[nd->last.len])) { 20401da177e4SLinus Torvalds dput(dentry); 20411da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 2042e9baf6e5SAl Viro } 2043e9baf6e5SAl Viro return dentry; 2044e9baf6e5SAl Viro eexist: 2045e9baf6e5SAl Viro dput(dentry); 2046e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 20471da177e4SLinus Torvalds fail: 20481da177e4SLinus Torvalds return dentry; 20491da177e4SLinus Torvalds } 2050f81a0bffSChristoph Hellwig EXPORT_SYMBOL_GPL(lookup_create); 20511da177e4SLinus Torvalds 20521da177e4SLinus Torvalds int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 20531da177e4SLinus Torvalds { 20541da177e4SLinus Torvalds int error = may_create(dir, dentry, NULL); 20551da177e4SLinus Torvalds 20561da177e4SLinus Torvalds if (error) 20571da177e4SLinus Torvalds return error; 20581da177e4SLinus Torvalds 20591da177e4SLinus Torvalds if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 20601da177e4SLinus Torvalds return -EPERM; 20611da177e4SLinus Torvalds 20621da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->mknod) 20631da177e4SLinus Torvalds return -EPERM; 20641da177e4SLinus Torvalds 206508ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 206608ce5f16SSerge E. Hallyn if (error) 206708ce5f16SSerge E. Hallyn return error; 206808ce5f16SSerge E. Hallyn 20691da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 20701da177e4SLinus Torvalds if (error) 20711da177e4SLinus Torvalds return error; 20721da177e4SLinus Torvalds 20731da177e4SLinus Torvalds DQUOT_INIT(dir); 20741da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 2075a74574aaSStephen Smalley if (!error) 2076f38aa942SAmy Griffis fsnotify_create(dir, dentry); 20771da177e4SLinus Torvalds return error; 20781da177e4SLinus Torvalds } 20791da177e4SLinus Torvalds 2080463c3197SDave Hansen static int may_mknod(mode_t mode) 2081463c3197SDave Hansen { 2082463c3197SDave Hansen switch (mode & S_IFMT) { 2083463c3197SDave Hansen case S_IFREG: 2084463c3197SDave Hansen case S_IFCHR: 2085463c3197SDave Hansen case S_IFBLK: 2086463c3197SDave Hansen case S_IFIFO: 2087463c3197SDave Hansen case S_IFSOCK: 2088463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 2089463c3197SDave Hansen return 0; 2090463c3197SDave Hansen case S_IFDIR: 2091463c3197SDave Hansen return -EPERM; 2092463c3197SDave Hansen default: 2093463c3197SDave Hansen return -EINVAL; 2094463c3197SDave Hansen } 2095463c3197SDave Hansen } 2096463c3197SDave Hansen 20975590ff0dSUlrich Drepper asmlinkage long sys_mknodat(int dfd, const char __user *filename, int mode, 20985590ff0dSUlrich Drepper unsigned dev) 20991da177e4SLinus Torvalds { 21001da177e4SLinus Torvalds int error = 0; 21011da177e4SLinus Torvalds char * tmp; 21021da177e4SLinus Torvalds struct dentry * dentry; 21031da177e4SLinus Torvalds struct nameidata nd; 21041da177e4SLinus Torvalds 21051da177e4SLinus Torvalds if (S_ISDIR(mode)) 21061da177e4SLinus Torvalds return -EPERM; 21071da177e4SLinus Torvalds tmp = getname(filename); 21081da177e4SLinus Torvalds if (IS_ERR(tmp)) 21091da177e4SLinus Torvalds return PTR_ERR(tmp); 21101da177e4SLinus Torvalds 21115590ff0dSUlrich Drepper error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd); 21121da177e4SLinus Torvalds if (error) 21131da177e4SLinus Torvalds goto out; 21141da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 2115463c3197SDave Hansen if (IS_ERR(dentry)) { 21161da177e4SLinus Torvalds error = PTR_ERR(dentry); 2117463c3197SDave Hansen goto out_unlock; 2118463c3197SDave Hansen } 21194ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 21201da177e4SLinus Torvalds mode &= ~current->fs->umask; 2121463c3197SDave Hansen error = may_mknod(mode); 2122463c3197SDave Hansen if (error) 2123463c3197SDave Hansen goto out_dput; 2124463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2125463c3197SDave Hansen if (error) 2126463c3197SDave Hansen goto out_dput; 21271da177e4SLinus Torvalds switch (mode & S_IFMT) { 21281da177e4SLinus Torvalds case 0: case S_IFREG: 21294ac91378SJan Blunck error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); 21301da177e4SLinus Torvalds break; 21311da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 21324ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, 21331da177e4SLinus Torvalds new_decode_dev(dev)); 21341da177e4SLinus Torvalds break; 21351da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 21364ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); 21371da177e4SLinus Torvalds break; 21381da177e4SLinus Torvalds } 2139463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2140463c3197SDave Hansen out_dput: 21411da177e4SLinus Torvalds dput(dentry); 2142463c3197SDave Hansen out_unlock: 21434ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 21441d957f9bSJan Blunck path_put(&nd.path); 21451da177e4SLinus Torvalds out: 21461da177e4SLinus Torvalds putname(tmp); 21471da177e4SLinus Torvalds 21481da177e4SLinus Torvalds return error; 21491da177e4SLinus Torvalds } 21501da177e4SLinus Torvalds 21515590ff0dSUlrich Drepper asmlinkage long sys_mknod(const char __user *filename, int mode, unsigned dev) 21525590ff0dSUlrich Drepper { 21535590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 21545590ff0dSUlrich Drepper } 21555590ff0dSUlrich Drepper 21561da177e4SLinus Torvalds int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 21571da177e4SLinus Torvalds { 21581da177e4SLinus Torvalds int error = may_create(dir, dentry, NULL); 21591da177e4SLinus Torvalds 21601da177e4SLinus Torvalds if (error) 21611da177e4SLinus Torvalds return error; 21621da177e4SLinus Torvalds 21631da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->mkdir) 21641da177e4SLinus Torvalds return -EPERM; 21651da177e4SLinus Torvalds 21661da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 21671da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 21681da177e4SLinus Torvalds if (error) 21691da177e4SLinus Torvalds return error; 21701da177e4SLinus Torvalds 21711da177e4SLinus Torvalds DQUOT_INIT(dir); 21721da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2173a74574aaSStephen Smalley if (!error) 2174f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 21751da177e4SLinus Torvalds return error; 21761da177e4SLinus Torvalds } 21771da177e4SLinus Torvalds 21785590ff0dSUlrich Drepper asmlinkage long sys_mkdirat(int dfd, const char __user *pathname, int mode) 21791da177e4SLinus Torvalds { 21801da177e4SLinus Torvalds int error = 0; 21811da177e4SLinus Torvalds char * tmp; 21826902d925SDave Hansen struct dentry *dentry; 21836902d925SDave Hansen struct nameidata nd; 21841da177e4SLinus Torvalds 21851da177e4SLinus Torvalds tmp = getname(pathname); 21861da177e4SLinus Torvalds error = PTR_ERR(tmp); 21876902d925SDave Hansen if (IS_ERR(tmp)) 21886902d925SDave Hansen goto out_err; 21891da177e4SLinus Torvalds 21905590ff0dSUlrich Drepper error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd); 21911da177e4SLinus Torvalds if (error) 21921da177e4SLinus Torvalds goto out; 21931da177e4SLinus Torvalds dentry = lookup_create(&nd, 1); 21941da177e4SLinus Torvalds error = PTR_ERR(dentry); 21956902d925SDave Hansen if (IS_ERR(dentry)) 21966902d925SDave Hansen goto out_unlock; 21976902d925SDave Hansen 21984ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 21991da177e4SLinus Torvalds mode &= ~current->fs->umask; 2200463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2201463c3197SDave Hansen if (error) 2202463c3197SDave Hansen goto out_dput; 22034ac91378SJan Blunck error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); 2204463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2205463c3197SDave Hansen out_dput: 22061da177e4SLinus Torvalds dput(dentry); 22076902d925SDave Hansen out_unlock: 22084ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 22091d957f9bSJan Blunck path_put(&nd.path); 22101da177e4SLinus Torvalds out: 22111da177e4SLinus Torvalds putname(tmp); 22126902d925SDave Hansen out_err: 22131da177e4SLinus Torvalds return error; 22141da177e4SLinus Torvalds } 22151da177e4SLinus Torvalds 22165590ff0dSUlrich Drepper asmlinkage long sys_mkdir(const char __user *pathname, int mode) 22175590ff0dSUlrich Drepper { 22185590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 22195590ff0dSUlrich Drepper } 22205590ff0dSUlrich Drepper 22211da177e4SLinus Torvalds /* 22221da177e4SLinus Torvalds * We try to drop the dentry early: we should have 22231da177e4SLinus Torvalds * a usage count of 2 if we're the only user of this 22241da177e4SLinus Torvalds * dentry, and if that is true (possibly after pruning 22251da177e4SLinus Torvalds * the dcache), then we drop the dentry now. 22261da177e4SLinus Torvalds * 22271da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 22281da177e4SLinus Torvalds * do a 22291da177e4SLinus Torvalds * 22301da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 22311da177e4SLinus Torvalds * return -EBUSY; 22321da177e4SLinus Torvalds * 22331da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 22341da177e4SLinus Torvalds * that is still in use by something else.. 22351da177e4SLinus Torvalds */ 22361da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 22371da177e4SLinus Torvalds { 22381da177e4SLinus Torvalds dget(dentry); 22391da177e4SLinus Torvalds shrink_dcache_parent(dentry); 22401da177e4SLinus Torvalds spin_lock(&dcache_lock); 22411da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 22421da177e4SLinus Torvalds if (atomic_read(&dentry->d_count) == 2) 22431da177e4SLinus Torvalds __d_drop(dentry); 22441da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 22451da177e4SLinus Torvalds spin_unlock(&dcache_lock); 22461da177e4SLinus Torvalds } 22471da177e4SLinus Torvalds 22481da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 22491da177e4SLinus Torvalds { 22501da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 22511da177e4SLinus Torvalds 22521da177e4SLinus Torvalds if (error) 22531da177e4SLinus Torvalds return error; 22541da177e4SLinus Torvalds 22551da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->rmdir) 22561da177e4SLinus Torvalds return -EPERM; 22571da177e4SLinus Torvalds 22581da177e4SLinus Torvalds DQUOT_INIT(dir); 22591da177e4SLinus Torvalds 22601b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 22611da177e4SLinus Torvalds dentry_unhash(dentry); 22621da177e4SLinus Torvalds if (d_mountpoint(dentry)) 22631da177e4SLinus Torvalds error = -EBUSY; 22641da177e4SLinus Torvalds else { 22651da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 22661da177e4SLinus Torvalds if (!error) { 22671da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 22681da177e4SLinus Torvalds if (!error) 22691da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 22701da177e4SLinus Torvalds } 22711da177e4SLinus Torvalds } 22721b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 22731da177e4SLinus Torvalds if (!error) { 22741da177e4SLinus Torvalds d_delete(dentry); 22751da177e4SLinus Torvalds } 22761da177e4SLinus Torvalds dput(dentry); 22771da177e4SLinus Torvalds 22781da177e4SLinus Torvalds return error; 22791da177e4SLinus Torvalds } 22801da177e4SLinus Torvalds 22815590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 22821da177e4SLinus Torvalds { 22831da177e4SLinus Torvalds int error = 0; 22841da177e4SLinus Torvalds char * name; 22851da177e4SLinus Torvalds struct dentry *dentry; 22861da177e4SLinus Torvalds struct nameidata nd; 22871da177e4SLinus Torvalds 22881da177e4SLinus Torvalds name = getname(pathname); 22891da177e4SLinus Torvalds if(IS_ERR(name)) 22901da177e4SLinus Torvalds return PTR_ERR(name); 22911da177e4SLinus Torvalds 22925590ff0dSUlrich Drepper error = do_path_lookup(dfd, name, LOOKUP_PARENT, &nd); 22931da177e4SLinus Torvalds if (error) 22941da177e4SLinus Torvalds goto exit; 22951da177e4SLinus Torvalds 22961da177e4SLinus Torvalds switch(nd.last_type) { 22971da177e4SLinus Torvalds case LAST_DOTDOT: 22981da177e4SLinus Torvalds error = -ENOTEMPTY; 22991da177e4SLinus Torvalds goto exit1; 23001da177e4SLinus Torvalds case LAST_DOT: 23011da177e4SLinus Torvalds error = -EINVAL; 23021da177e4SLinus Torvalds goto exit1; 23031da177e4SLinus Torvalds case LAST_ROOT: 23041da177e4SLinus Torvalds error = -EBUSY; 23051da177e4SLinus Torvalds goto exit1; 23061da177e4SLinus Torvalds } 23074ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 230849705b77SChristoph Hellwig dentry = lookup_hash(&nd); 23091da177e4SLinus Torvalds error = PTR_ERR(dentry); 23106902d925SDave Hansen if (IS_ERR(dentry)) 23116902d925SDave Hansen goto exit2; 23120622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 23130622753bSDave Hansen if (error) 23140622753bSDave Hansen goto exit3; 23154ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 23160622753bSDave Hansen mnt_drop_write(nd.path.mnt); 23170622753bSDave Hansen exit3: 23181da177e4SLinus Torvalds dput(dentry); 23196902d925SDave Hansen exit2: 23204ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 23211da177e4SLinus Torvalds exit1: 23221d957f9bSJan Blunck path_put(&nd.path); 23231da177e4SLinus Torvalds exit: 23241da177e4SLinus Torvalds putname(name); 23251da177e4SLinus Torvalds return error; 23261da177e4SLinus Torvalds } 23271da177e4SLinus Torvalds 23285590ff0dSUlrich Drepper asmlinkage long sys_rmdir(const char __user *pathname) 23295590ff0dSUlrich Drepper { 23305590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 23315590ff0dSUlrich Drepper } 23325590ff0dSUlrich Drepper 23331da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 23341da177e4SLinus Torvalds { 23351da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 23361da177e4SLinus Torvalds 23371da177e4SLinus Torvalds if (error) 23381da177e4SLinus Torvalds return error; 23391da177e4SLinus Torvalds 23401da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->unlink) 23411da177e4SLinus Torvalds return -EPERM; 23421da177e4SLinus Torvalds 23431da177e4SLinus Torvalds DQUOT_INIT(dir); 23441da177e4SLinus Torvalds 23451b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 23461da177e4SLinus Torvalds if (d_mountpoint(dentry)) 23471da177e4SLinus Torvalds error = -EBUSY; 23481da177e4SLinus Torvalds else { 23491da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 23501da177e4SLinus Torvalds if (!error) 23511da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 23521da177e4SLinus Torvalds } 23531b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 23541da177e4SLinus Torvalds 23551da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 23561da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2357ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 23581da177e4SLinus Torvalds d_delete(dentry); 23591da177e4SLinus Torvalds } 23600eeca283SRobert Love 23611da177e4SLinus Torvalds return error; 23621da177e4SLinus Torvalds } 23631da177e4SLinus Torvalds 23641da177e4SLinus Torvalds /* 23651da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 23661b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 23671da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 23681da177e4SLinus Torvalds * while waiting on the I/O. 23691da177e4SLinus Torvalds */ 23705590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 23711da177e4SLinus Torvalds { 23721da177e4SLinus Torvalds int error = 0; 23731da177e4SLinus Torvalds char * name; 23741da177e4SLinus Torvalds struct dentry *dentry; 23751da177e4SLinus Torvalds struct nameidata nd; 23761da177e4SLinus Torvalds struct inode *inode = NULL; 23771da177e4SLinus Torvalds 23781da177e4SLinus Torvalds name = getname(pathname); 23791da177e4SLinus Torvalds if(IS_ERR(name)) 23801da177e4SLinus Torvalds return PTR_ERR(name); 23811da177e4SLinus Torvalds 23825590ff0dSUlrich Drepper error = do_path_lookup(dfd, name, LOOKUP_PARENT, &nd); 23831da177e4SLinus Torvalds if (error) 23841da177e4SLinus Torvalds goto exit; 23851da177e4SLinus Torvalds error = -EISDIR; 23861da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 23871da177e4SLinus Torvalds goto exit1; 23884ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 238949705b77SChristoph Hellwig dentry = lookup_hash(&nd); 23901da177e4SLinus Torvalds error = PTR_ERR(dentry); 23911da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 23921da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 23931da177e4SLinus Torvalds if (nd.last.name[nd.last.len]) 23941da177e4SLinus Torvalds goto slashes; 23951da177e4SLinus Torvalds inode = dentry->d_inode; 23961da177e4SLinus Torvalds if (inode) 23971da177e4SLinus Torvalds atomic_inc(&inode->i_count); 23980622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 23990622753bSDave Hansen if (error) 24000622753bSDave Hansen goto exit2; 24014ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 24020622753bSDave Hansen mnt_drop_write(nd.path.mnt); 24031da177e4SLinus Torvalds exit2: 24041da177e4SLinus Torvalds dput(dentry); 24051da177e4SLinus Torvalds } 24064ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 24071da177e4SLinus Torvalds if (inode) 24081da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 24091da177e4SLinus Torvalds exit1: 24101d957f9bSJan Blunck path_put(&nd.path); 24111da177e4SLinus Torvalds exit: 24121da177e4SLinus Torvalds putname(name); 24131da177e4SLinus Torvalds return error; 24141da177e4SLinus Torvalds 24151da177e4SLinus Torvalds slashes: 24161da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 24171da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 24181da177e4SLinus Torvalds goto exit2; 24191da177e4SLinus Torvalds } 24201da177e4SLinus Torvalds 24215590ff0dSUlrich Drepper asmlinkage long sys_unlinkat(int dfd, const char __user *pathname, int flag) 24225590ff0dSUlrich Drepper { 24235590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 24245590ff0dSUlrich Drepper return -EINVAL; 24255590ff0dSUlrich Drepper 24265590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 24275590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 24285590ff0dSUlrich Drepper 24295590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 24305590ff0dSUlrich Drepper } 24315590ff0dSUlrich Drepper 24325590ff0dSUlrich Drepper asmlinkage long sys_unlink(const char __user *pathname) 24335590ff0dSUlrich Drepper { 24345590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 24355590ff0dSUlrich Drepper } 24365590ff0dSUlrich Drepper 24371da177e4SLinus Torvalds int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname, int mode) 24381da177e4SLinus Torvalds { 24391da177e4SLinus Torvalds int error = may_create(dir, dentry, NULL); 24401da177e4SLinus Torvalds 24411da177e4SLinus Torvalds if (error) 24421da177e4SLinus Torvalds return error; 24431da177e4SLinus Torvalds 24441da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->symlink) 24451da177e4SLinus Torvalds return -EPERM; 24461da177e4SLinus Torvalds 24471da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 24481da177e4SLinus Torvalds if (error) 24491da177e4SLinus Torvalds return error; 24501da177e4SLinus Torvalds 24511da177e4SLinus Torvalds DQUOT_INIT(dir); 24521da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2453a74574aaSStephen Smalley if (!error) 2454f38aa942SAmy Griffis fsnotify_create(dir, dentry); 24551da177e4SLinus Torvalds return error; 24561da177e4SLinus Torvalds } 24571da177e4SLinus Torvalds 24585590ff0dSUlrich Drepper asmlinkage long sys_symlinkat(const char __user *oldname, 24595590ff0dSUlrich Drepper int newdfd, const char __user *newname) 24601da177e4SLinus Torvalds { 24611da177e4SLinus Torvalds int error = 0; 24621da177e4SLinus Torvalds char * from; 24631da177e4SLinus Torvalds char * to; 24646902d925SDave Hansen struct dentry *dentry; 24656902d925SDave Hansen struct nameidata nd; 24661da177e4SLinus Torvalds 24671da177e4SLinus Torvalds from = getname(oldname); 24681da177e4SLinus Torvalds if(IS_ERR(from)) 24691da177e4SLinus Torvalds return PTR_ERR(from); 24701da177e4SLinus Torvalds to = getname(newname); 24711da177e4SLinus Torvalds error = PTR_ERR(to); 24726902d925SDave Hansen if (IS_ERR(to)) 24736902d925SDave Hansen goto out_putname; 24741da177e4SLinus Torvalds 24755590ff0dSUlrich Drepper error = do_path_lookup(newdfd, to, LOOKUP_PARENT, &nd); 24761da177e4SLinus Torvalds if (error) 24771da177e4SLinus Torvalds goto out; 24781da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 24791da177e4SLinus Torvalds error = PTR_ERR(dentry); 24806902d925SDave Hansen if (IS_ERR(dentry)) 24816902d925SDave Hansen goto out_unlock; 24826902d925SDave Hansen 248375c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 248475c3f29dSDave Hansen if (error) 248575c3f29dSDave Hansen goto out_dput; 24864ac91378SJan Blunck error = vfs_symlink(nd.path.dentry->d_inode, dentry, from, S_IALLUGO); 248775c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 248875c3f29dSDave Hansen out_dput: 24891da177e4SLinus Torvalds dput(dentry); 24906902d925SDave Hansen out_unlock: 24914ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 24921d957f9bSJan Blunck path_put(&nd.path); 24931da177e4SLinus Torvalds out: 24941da177e4SLinus Torvalds putname(to); 24956902d925SDave Hansen out_putname: 24961da177e4SLinus Torvalds putname(from); 24971da177e4SLinus Torvalds return error; 24981da177e4SLinus Torvalds } 24991da177e4SLinus Torvalds 25005590ff0dSUlrich Drepper asmlinkage long sys_symlink(const char __user *oldname, const char __user *newname) 25015590ff0dSUlrich Drepper { 25025590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 25035590ff0dSUlrich Drepper } 25045590ff0dSUlrich Drepper 25051da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 25061da177e4SLinus Torvalds { 25071da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 25081da177e4SLinus Torvalds int error; 25091da177e4SLinus Torvalds 25101da177e4SLinus Torvalds if (!inode) 25111da177e4SLinus Torvalds return -ENOENT; 25121da177e4SLinus Torvalds 25131da177e4SLinus Torvalds error = may_create(dir, new_dentry, NULL); 25141da177e4SLinus Torvalds if (error) 25151da177e4SLinus Torvalds return error; 25161da177e4SLinus Torvalds 25171da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 25181da177e4SLinus Torvalds return -EXDEV; 25191da177e4SLinus Torvalds 25201da177e4SLinus Torvalds /* 25211da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 25221da177e4SLinus Torvalds */ 25231da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 25241da177e4SLinus Torvalds return -EPERM; 25251da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->link) 25261da177e4SLinus Torvalds return -EPERM; 25271da177e4SLinus Torvalds if (S_ISDIR(old_dentry->d_inode->i_mode)) 25281da177e4SLinus Torvalds return -EPERM; 25291da177e4SLinus Torvalds 25301da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 25311da177e4SLinus Torvalds if (error) 25321da177e4SLinus Torvalds return error; 25331da177e4SLinus Torvalds 25341b1dcc1bSJes Sorensen mutex_lock(&old_dentry->d_inode->i_mutex); 25351da177e4SLinus Torvalds DQUOT_INIT(dir); 25361da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 25371b1dcc1bSJes Sorensen mutex_unlock(&old_dentry->d_inode->i_mutex); 2538e31e14ecSStephen Smalley if (!error) 2539ece95912SJan Kara fsnotify_link(dir, old_dentry->d_inode, new_dentry); 25401da177e4SLinus Torvalds return error; 25411da177e4SLinus Torvalds } 25421da177e4SLinus Torvalds 25431da177e4SLinus Torvalds /* 25441da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 25451da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 25461da177e4SLinus Torvalds * newname. --KAB 25471da177e4SLinus Torvalds * 25481da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 25491da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 25501da177e4SLinus Torvalds * and other special files. --ADM 25511da177e4SLinus Torvalds */ 25525590ff0dSUlrich Drepper asmlinkage long sys_linkat(int olddfd, const char __user *oldname, 2553c04030e1SUlrich Drepper int newdfd, const char __user *newname, 2554c04030e1SUlrich Drepper int flags) 25551da177e4SLinus Torvalds { 25561da177e4SLinus Torvalds struct dentry *new_dentry; 25571da177e4SLinus Torvalds struct nameidata nd, old_nd; 25581da177e4SLinus Torvalds int error; 25591da177e4SLinus Torvalds char * to; 25601da177e4SLinus Torvalds 256145c9b11aSUlrich Drepper if ((flags & ~AT_SYMLINK_FOLLOW) != 0) 2562c04030e1SUlrich Drepper return -EINVAL; 2563c04030e1SUlrich Drepper 25641da177e4SLinus Torvalds to = getname(newname); 25651da177e4SLinus Torvalds if (IS_ERR(to)) 25661da177e4SLinus Torvalds return PTR_ERR(to); 25671da177e4SLinus Torvalds 256845c9b11aSUlrich Drepper error = __user_walk_fd(olddfd, oldname, 256945c9b11aSUlrich Drepper flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0, 257045c9b11aSUlrich Drepper &old_nd); 25711da177e4SLinus Torvalds if (error) 25721da177e4SLinus Torvalds goto exit; 25735590ff0dSUlrich Drepper error = do_path_lookup(newdfd, to, LOOKUP_PARENT, &nd); 25741da177e4SLinus Torvalds if (error) 25751da177e4SLinus Torvalds goto out; 25761da177e4SLinus Torvalds error = -EXDEV; 25774ac91378SJan Blunck if (old_nd.path.mnt != nd.path.mnt) 25781da177e4SLinus Torvalds goto out_release; 25791da177e4SLinus Torvalds new_dentry = lookup_create(&nd, 0); 25801da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 25816902d925SDave Hansen if (IS_ERR(new_dentry)) 25826902d925SDave Hansen goto out_unlock; 258375c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 258475c3f29dSDave Hansen if (error) 258575c3f29dSDave Hansen goto out_dput; 25864ac91378SJan Blunck error = vfs_link(old_nd.path.dentry, nd.path.dentry->d_inode, new_dentry); 258775c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 258875c3f29dSDave Hansen out_dput: 25891da177e4SLinus Torvalds dput(new_dentry); 25906902d925SDave Hansen out_unlock: 25914ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 25921da177e4SLinus Torvalds out_release: 25931d957f9bSJan Blunck path_put(&nd.path); 25941da177e4SLinus Torvalds out: 25951d957f9bSJan Blunck path_put(&old_nd.path); 25961da177e4SLinus Torvalds exit: 25971da177e4SLinus Torvalds putname(to); 25981da177e4SLinus Torvalds 25991da177e4SLinus Torvalds return error; 26001da177e4SLinus Torvalds } 26011da177e4SLinus Torvalds 26025590ff0dSUlrich Drepper asmlinkage long sys_link(const char __user *oldname, const char __user *newname) 26035590ff0dSUlrich Drepper { 2604c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 26055590ff0dSUlrich Drepper } 26065590ff0dSUlrich Drepper 26071da177e4SLinus Torvalds /* 26081da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 26091da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 26101da177e4SLinus Torvalds * Problems: 26111da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 26121da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 26131da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 2614a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 26151da177e4SLinus Torvalds * story. 26161da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 26171b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 26181da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 26191da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 2620a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 26211da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 26221da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 26231da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 2624a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 26251da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 26261da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 26271da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 26281da177e4SLinus Torvalds * d) some filesystems don't support opened-but-unlinked directories, 26291da177e4SLinus Torvalds * either because of layout or because they are not ready to deal with 26301da177e4SLinus Torvalds * all cases correctly. The latter will be fixed (taking this sort of 26311da177e4SLinus Torvalds * stuff into VFS), but the former is not going away. Solution: the same 26321da177e4SLinus Torvalds * trick as in rmdir(). 26331da177e4SLinus Torvalds * e) conversion from fhandle to dentry may come in the wrong moment - when 26341b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 26351da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 26361b1dcc1bSJes Sorensen * ->i_mutex on parents, which works but leads to some truely excessive 26371da177e4SLinus Torvalds * locking]. 26381da177e4SLinus Torvalds */ 263975c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 26401da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 26411da177e4SLinus Torvalds { 26421da177e4SLinus Torvalds int error = 0; 26431da177e4SLinus Torvalds struct inode *target; 26441da177e4SLinus Torvalds 26451da177e4SLinus Torvalds /* 26461da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 26471da177e4SLinus Torvalds * we'll need to flip '..'. 26481da177e4SLinus Torvalds */ 26491da177e4SLinus Torvalds if (new_dir != old_dir) { 26501da177e4SLinus Torvalds error = permission(old_dentry->d_inode, MAY_WRITE, NULL); 26511da177e4SLinus Torvalds if (error) 26521da177e4SLinus Torvalds return error; 26531da177e4SLinus Torvalds } 26541da177e4SLinus Torvalds 26551da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 26561da177e4SLinus Torvalds if (error) 26571da177e4SLinus Torvalds return error; 26581da177e4SLinus Torvalds 26591da177e4SLinus Torvalds target = new_dentry->d_inode; 26601da177e4SLinus Torvalds if (target) { 26611b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 26621da177e4SLinus Torvalds dentry_unhash(new_dentry); 26631da177e4SLinus Torvalds } 26641da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 26651da177e4SLinus Torvalds error = -EBUSY; 26661da177e4SLinus Torvalds else 26671da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 26681da177e4SLinus Torvalds if (target) { 26691da177e4SLinus Torvalds if (!error) 26701da177e4SLinus Torvalds target->i_flags |= S_DEAD; 26711b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 26721da177e4SLinus Torvalds if (d_unhashed(new_dentry)) 26731da177e4SLinus Torvalds d_rehash(new_dentry); 26741da177e4SLinus Torvalds dput(new_dentry); 26751da177e4SLinus Torvalds } 2676e31e14ecSStephen Smalley if (!error) 2677349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 26781da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 26791da177e4SLinus Torvalds return error; 26801da177e4SLinus Torvalds } 26811da177e4SLinus Torvalds 268275c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 26831da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 26841da177e4SLinus Torvalds { 26851da177e4SLinus Torvalds struct inode *target; 26861da177e4SLinus Torvalds int error; 26871da177e4SLinus Torvalds 26881da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 26891da177e4SLinus Torvalds if (error) 26901da177e4SLinus Torvalds return error; 26911da177e4SLinus Torvalds 26921da177e4SLinus Torvalds dget(new_dentry); 26931da177e4SLinus Torvalds target = new_dentry->d_inode; 26941da177e4SLinus Torvalds if (target) 26951b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 26961da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 26971da177e4SLinus Torvalds error = -EBUSY; 26981da177e4SLinus Torvalds else 26991da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 27001da177e4SLinus Torvalds if (!error) { 2701349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 27021da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 27031da177e4SLinus Torvalds } 27041da177e4SLinus Torvalds if (target) 27051b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 27061da177e4SLinus Torvalds dput(new_dentry); 27071da177e4SLinus Torvalds return error; 27081da177e4SLinus Torvalds } 27091da177e4SLinus Torvalds 27101da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 27111da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 27121da177e4SLinus Torvalds { 27131da177e4SLinus Torvalds int error; 27141da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 27150eeca283SRobert Love const char *old_name; 27161da177e4SLinus Torvalds 27171da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 27181da177e4SLinus Torvalds return 0; 27191da177e4SLinus Torvalds 27201da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 27211da177e4SLinus Torvalds if (error) 27221da177e4SLinus Torvalds return error; 27231da177e4SLinus Torvalds 27241da177e4SLinus Torvalds if (!new_dentry->d_inode) 27251da177e4SLinus Torvalds error = may_create(new_dir, new_dentry, NULL); 27261da177e4SLinus Torvalds else 27271da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 27281da177e4SLinus Torvalds if (error) 27291da177e4SLinus Torvalds return error; 27301da177e4SLinus Torvalds 27311da177e4SLinus Torvalds if (!old_dir->i_op || !old_dir->i_op->rename) 27321da177e4SLinus Torvalds return -EPERM; 27331da177e4SLinus Torvalds 27341da177e4SLinus Torvalds DQUOT_INIT(old_dir); 27351da177e4SLinus Torvalds DQUOT_INIT(new_dir); 27361da177e4SLinus Torvalds 27370eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 27380eeca283SRobert Love 27391da177e4SLinus Torvalds if (is_dir) 27401da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 27411da177e4SLinus Torvalds else 27421da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 27431da177e4SLinus Torvalds if (!error) { 27440eeca283SRobert Love const char *new_name = old_dentry->d_name.name; 274589204c40SJohn McCutchan fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir, 27465a190ae6SAl Viro new_dentry->d_inode, old_dentry); 27471da177e4SLinus Torvalds } 27480eeca283SRobert Love fsnotify_oldname_free(old_name); 27490eeca283SRobert Love 27501da177e4SLinus Torvalds return error; 27511da177e4SLinus Torvalds } 27521da177e4SLinus Torvalds 27535590ff0dSUlrich Drepper static int do_rename(int olddfd, const char *oldname, 27545590ff0dSUlrich Drepper int newdfd, const char *newname) 27551da177e4SLinus Torvalds { 27561da177e4SLinus Torvalds int error = 0; 27571da177e4SLinus Torvalds struct dentry * old_dir, * new_dir; 27581da177e4SLinus Torvalds struct dentry * old_dentry, *new_dentry; 27591da177e4SLinus Torvalds struct dentry * trap; 27601da177e4SLinus Torvalds struct nameidata oldnd, newnd; 27611da177e4SLinus Torvalds 27625590ff0dSUlrich Drepper error = do_path_lookup(olddfd, oldname, LOOKUP_PARENT, &oldnd); 27631da177e4SLinus Torvalds if (error) 27641da177e4SLinus Torvalds goto exit; 27651da177e4SLinus Torvalds 27665590ff0dSUlrich Drepper error = do_path_lookup(newdfd, newname, LOOKUP_PARENT, &newnd); 27671da177e4SLinus Torvalds if (error) 27681da177e4SLinus Torvalds goto exit1; 27691da177e4SLinus Torvalds 27701da177e4SLinus Torvalds error = -EXDEV; 27714ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 27721da177e4SLinus Torvalds goto exit2; 27731da177e4SLinus Torvalds 27744ac91378SJan Blunck old_dir = oldnd.path.dentry; 27751da177e4SLinus Torvalds error = -EBUSY; 27761da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 27771da177e4SLinus Torvalds goto exit2; 27781da177e4SLinus Torvalds 27794ac91378SJan Blunck new_dir = newnd.path.dentry; 27801da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 27811da177e4SLinus Torvalds goto exit2; 27821da177e4SLinus Torvalds 27831da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 27841da177e4SLinus Torvalds 278549705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 27861da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 27871da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 27881da177e4SLinus Torvalds goto exit3; 27891da177e4SLinus Torvalds /* source must exist */ 27901da177e4SLinus Torvalds error = -ENOENT; 27911da177e4SLinus Torvalds if (!old_dentry->d_inode) 27921da177e4SLinus Torvalds goto exit4; 27931da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 27941da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 27951da177e4SLinus Torvalds error = -ENOTDIR; 27961da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 27971da177e4SLinus Torvalds goto exit4; 27981da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 27991da177e4SLinus Torvalds goto exit4; 28001da177e4SLinus Torvalds } 28011da177e4SLinus Torvalds /* source should not be ancestor of target */ 28021da177e4SLinus Torvalds error = -EINVAL; 28031da177e4SLinus Torvalds if (old_dentry == trap) 28041da177e4SLinus Torvalds goto exit4; 280549705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 28061da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 28071da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 28081da177e4SLinus Torvalds goto exit4; 28091da177e4SLinus Torvalds /* target should not be an ancestor of source */ 28101da177e4SLinus Torvalds error = -ENOTEMPTY; 28111da177e4SLinus Torvalds if (new_dentry == trap) 28121da177e4SLinus Torvalds goto exit5; 28131da177e4SLinus Torvalds 28149079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 28159079b1ebSDave Hansen if (error) 28169079b1ebSDave Hansen goto exit5; 28171da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 28181da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 28199079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 28201da177e4SLinus Torvalds exit5: 28211da177e4SLinus Torvalds dput(new_dentry); 28221da177e4SLinus Torvalds exit4: 28231da177e4SLinus Torvalds dput(old_dentry); 28241da177e4SLinus Torvalds exit3: 28251da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 28261da177e4SLinus Torvalds exit2: 28271d957f9bSJan Blunck path_put(&newnd.path); 28281da177e4SLinus Torvalds exit1: 28291d957f9bSJan Blunck path_put(&oldnd.path); 28301da177e4SLinus Torvalds exit: 28311da177e4SLinus Torvalds return error; 28321da177e4SLinus Torvalds } 28331da177e4SLinus Torvalds 28345590ff0dSUlrich Drepper asmlinkage long sys_renameat(int olddfd, const char __user *oldname, 28355590ff0dSUlrich Drepper int newdfd, const char __user *newname) 28361da177e4SLinus Torvalds { 28371da177e4SLinus Torvalds int error; 28381da177e4SLinus Torvalds char * from; 28391da177e4SLinus Torvalds char * to; 28401da177e4SLinus Torvalds 28411da177e4SLinus Torvalds from = getname(oldname); 28421da177e4SLinus Torvalds if(IS_ERR(from)) 28431da177e4SLinus Torvalds return PTR_ERR(from); 28441da177e4SLinus Torvalds to = getname(newname); 28451da177e4SLinus Torvalds error = PTR_ERR(to); 28461da177e4SLinus Torvalds if (!IS_ERR(to)) { 28475590ff0dSUlrich Drepper error = do_rename(olddfd, from, newdfd, to); 28481da177e4SLinus Torvalds putname(to); 28491da177e4SLinus Torvalds } 28501da177e4SLinus Torvalds putname(from); 28511da177e4SLinus Torvalds return error; 28521da177e4SLinus Torvalds } 28531da177e4SLinus Torvalds 28545590ff0dSUlrich Drepper asmlinkage long sys_rename(const char __user *oldname, const char __user *newname) 28555590ff0dSUlrich Drepper { 28565590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 28575590ff0dSUlrich Drepper } 28585590ff0dSUlrich Drepper 28591da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 28601da177e4SLinus Torvalds { 28611da177e4SLinus Torvalds int len; 28621da177e4SLinus Torvalds 28631da177e4SLinus Torvalds len = PTR_ERR(link); 28641da177e4SLinus Torvalds if (IS_ERR(link)) 28651da177e4SLinus Torvalds goto out; 28661da177e4SLinus Torvalds 28671da177e4SLinus Torvalds len = strlen(link); 28681da177e4SLinus Torvalds if (len > (unsigned) buflen) 28691da177e4SLinus Torvalds len = buflen; 28701da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 28711da177e4SLinus Torvalds len = -EFAULT; 28721da177e4SLinus Torvalds out: 28731da177e4SLinus Torvalds return len; 28741da177e4SLinus Torvalds } 28751da177e4SLinus Torvalds 28761da177e4SLinus Torvalds /* 28771da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 28781da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 28791da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 28801da177e4SLinus Torvalds */ 28811da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 28821da177e4SLinus Torvalds { 28831da177e4SLinus Torvalds struct nameidata nd; 2884cc314eefSLinus Torvalds void *cookie; 2885694a1764SMarcin Slusarz int res; 2886cc314eefSLinus Torvalds 28871da177e4SLinus Torvalds nd.depth = 0; 2888cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 2889694a1764SMarcin Slusarz if (IS_ERR(cookie)) 2890694a1764SMarcin Slusarz return PTR_ERR(cookie); 2891694a1764SMarcin Slusarz 2892694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 28931da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 2894cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 2895694a1764SMarcin Slusarz return res; 28961da177e4SLinus Torvalds } 28971da177e4SLinus Torvalds 28981da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 28991da177e4SLinus Torvalds { 29001da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 29011da177e4SLinus Torvalds } 29021da177e4SLinus Torvalds 29031da177e4SLinus Torvalds /* get the link contents into pagecache */ 29041da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 29051da177e4SLinus Torvalds { 29061da177e4SLinus Torvalds struct page * page; 29071da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 2908090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 29091da177e4SLinus Torvalds if (IS_ERR(page)) 29106fe6900eSNick Piggin return (char*)page; 29111da177e4SLinus Torvalds *ppage = page; 29121da177e4SLinus Torvalds return kmap(page); 29131da177e4SLinus Torvalds } 29141da177e4SLinus Torvalds 29151da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 29161da177e4SLinus Torvalds { 29171da177e4SLinus Torvalds struct page *page = NULL; 29181da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 29191da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 29201da177e4SLinus Torvalds if (page) { 29211da177e4SLinus Torvalds kunmap(page); 29221da177e4SLinus Torvalds page_cache_release(page); 29231da177e4SLinus Torvalds } 29241da177e4SLinus Torvalds return res; 29251da177e4SLinus Torvalds } 29261da177e4SLinus Torvalds 2927cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 29281da177e4SLinus Torvalds { 2929cc314eefSLinus Torvalds struct page *page = NULL; 29301da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 2931cc314eefSLinus Torvalds return page; 29321da177e4SLinus Torvalds } 29331da177e4SLinus Torvalds 2934cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 29351da177e4SLinus Torvalds { 2936cc314eefSLinus Torvalds struct page *page = cookie; 2937cc314eefSLinus Torvalds 2938cc314eefSLinus Torvalds if (page) { 29391da177e4SLinus Torvalds kunmap(page); 29401da177e4SLinus Torvalds page_cache_release(page); 29411da177e4SLinus Torvalds } 29421da177e4SLinus Torvalds } 29431da177e4SLinus Torvalds 29440adb25d2SKirill Korotaev int __page_symlink(struct inode *inode, const char *symname, int len, 29450adb25d2SKirill Korotaev gfp_t gfp_mask) 29461da177e4SLinus Torvalds { 29471da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 29480adb25d2SKirill Korotaev struct page *page; 2949afddba49SNick Piggin void *fsdata; 2950beb497abSDmitriy Monakhov int err; 29511da177e4SLinus Torvalds char *kaddr; 29521da177e4SLinus Torvalds 29537e53cac4SNeilBrown retry: 2954afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 2955afddba49SNick Piggin AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata); 29561da177e4SLinus Torvalds if (err) 2957afddba49SNick Piggin goto fail; 2958afddba49SNick Piggin 29591da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 29601da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 29611da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 2962afddba49SNick Piggin 2963afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 2964afddba49SNick Piggin page, fsdata); 29651da177e4SLinus Torvalds if (err < 0) 29661da177e4SLinus Torvalds goto fail; 2967afddba49SNick Piggin if (err < len-1) 2968afddba49SNick Piggin goto retry; 2969afddba49SNick Piggin 29701da177e4SLinus Torvalds mark_inode_dirty(inode); 29711da177e4SLinus Torvalds return 0; 29721da177e4SLinus Torvalds fail: 29731da177e4SLinus Torvalds return err; 29741da177e4SLinus Torvalds } 29751da177e4SLinus Torvalds 29760adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 29770adb25d2SKirill Korotaev { 29780adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 29790adb25d2SKirill Korotaev mapping_gfp_mask(inode->i_mapping)); 29800adb25d2SKirill Korotaev } 29810adb25d2SKirill Korotaev 298292e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 29831da177e4SLinus Torvalds .readlink = generic_readlink, 29841da177e4SLinus Torvalds .follow_link = page_follow_link_light, 29851da177e4SLinus Torvalds .put_link = page_put_link, 29861da177e4SLinus Torvalds }; 29871da177e4SLinus Torvalds 29881da177e4SLinus Torvalds EXPORT_SYMBOL(__user_walk); 29895590ff0dSUlrich Drepper EXPORT_SYMBOL(__user_walk_fd); 29901da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 29911da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 29921da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 29931da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 29941da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 29951da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 29961da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 29971da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 29981da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 29990adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 30001da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 30011da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 30021da177e4SLinus Torvalds EXPORT_SYMBOL(path_lookup); 300316f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 30041da177e4SLinus Torvalds EXPORT_SYMBOL(permission); 3005e4543eddSChristoph Hellwig EXPORT_SYMBOL(vfs_permission); 30068c744fb8SChristoph Hellwig EXPORT_SYMBOL(file_permission); 30071da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 30081da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 30091da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 30101da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 30111da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 30121da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 30131da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 30141da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 30151da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 30161da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 30171da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 30181da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 30191da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 30201da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 3021