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 1881da177e4SLinus Torvalds if (current->fsuid == inode->i_uid) 1891da177e4SLinus Torvalds mode >>= 6; 1901da177e4SLinus Torvalds else { 1911da177e4SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) { 1921da177e4SLinus Torvalds int error = check_acl(inode, mask); 1931da177e4SLinus Torvalds if (error == -EACCES) 1941da177e4SLinus Torvalds goto check_capabilities; 1951da177e4SLinus Torvalds else if (error != -EAGAIN) 1961da177e4SLinus Torvalds return error; 1971da177e4SLinus Torvalds } 1981da177e4SLinus Torvalds 1991da177e4SLinus Torvalds if (in_group_p(inode->i_gid)) 2001da177e4SLinus Torvalds mode >>= 3; 2011da177e4SLinus Torvalds } 2021da177e4SLinus Torvalds 2031da177e4SLinus Torvalds /* 2041da177e4SLinus Torvalds * If the DACs are ok we don't need any capability check. 2051da177e4SLinus Torvalds */ 2061da177e4SLinus Torvalds if (((mode & mask & (MAY_READ|MAY_WRITE|MAY_EXEC)) == mask)) 2071da177e4SLinus Torvalds return 0; 2081da177e4SLinus Torvalds 2091da177e4SLinus Torvalds check_capabilities: 2101da177e4SLinus Torvalds /* 2111da177e4SLinus Torvalds * Read/write DACs are always overridable. 2121da177e4SLinus Torvalds * Executable DACs are overridable if at least one exec bit is set. 2131da177e4SLinus Torvalds */ 2141da177e4SLinus Torvalds if (!(mask & MAY_EXEC) || 2151da177e4SLinus Torvalds (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode)) 2161da177e4SLinus Torvalds if (capable(CAP_DAC_OVERRIDE)) 2171da177e4SLinus Torvalds return 0; 2181da177e4SLinus Torvalds 2191da177e4SLinus Torvalds /* 2201da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 2211da177e4SLinus Torvalds */ 2221da177e4SLinus Torvalds if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))) 2231da177e4SLinus Torvalds if (capable(CAP_DAC_READ_SEARCH)) 2241da177e4SLinus Torvalds return 0; 2251da177e4SLinus Torvalds 2261da177e4SLinus Torvalds return -EACCES; 2271da177e4SLinus Torvalds } 2281da177e4SLinus Torvalds 2291da177e4SLinus Torvalds int permission(struct inode *inode, int mask, struct nameidata *nd) 2301da177e4SLinus Torvalds { 2311da177e4SLinus Torvalds int retval, submask; 232c7eb2667SDave Hansen struct vfsmount *mnt = NULL; 233c7eb2667SDave Hansen 234c7eb2667SDave Hansen if (nd) 2354ac91378SJan Blunck mnt = nd->path.mnt; 2361da177e4SLinus Torvalds 2371da177e4SLinus Torvalds if (mask & MAY_WRITE) { 23822590e41SMiklos Szeredi umode_t mode = inode->i_mode; 2391da177e4SLinus Torvalds 2401da177e4SLinus Torvalds /* 2411da177e4SLinus Torvalds * Nobody gets write access to a read-only fs. 2421da177e4SLinus Torvalds */ 2431da177e4SLinus Torvalds if (IS_RDONLY(inode) && 2441da177e4SLinus Torvalds (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 2451da177e4SLinus Torvalds return -EROFS; 2461da177e4SLinus Torvalds 2471da177e4SLinus Torvalds /* 2481da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 2491da177e4SLinus Torvalds */ 2501da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 2511da177e4SLinus Torvalds return -EACCES; 2521da177e4SLinus Torvalds } 2531da177e4SLinus Torvalds 25422590e41SMiklos Szeredi if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode)) { 255a343bb77STrond Myklebust /* 25622590e41SMiklos Szeredi * MAY_EXEC on regular files is denied if the fs is mounted 25722590e41SMiklos Szeredi * with the "noexec" flag. 258a343bb77STrond Myklebust */ 259c7eb2667SDave Hansen if (mnt && (mnt->mnt_flags & MNT_NOEXEC)) 260a343bb77STrond Myklebust return -EACCES; 26122590e41SMiklos Szeredi } 262a343bb77STrond Myklebust 2631da177e4SLinus Torvalds /* Ordinary permission routines do not understand MAY_APPEND. */ 2641da177e4SLinus Torvalds submask = mask & ~MAY_APPEND; 26522590e41SMiklos Szeredi if (inode->i_op && inode->i_op->permission) { 2661da177e4SLinus Torvalds retval = inode->i_op->permission(inode, submask, nd); 26722590e41SMiklos Szeredi if (!retval) { 26822590e41SMiklos Szeredi /* 26922590e41SMiklos Szeredi * Exec permission on a regular file is denied if none 27022590e41SMiklos Szeredi * of the execute bits are set. 27122590e41SMiklos Szeredi * 27222590e41SMiklos Szeredi * This check should be done by the ->permission() 27322590e41SMiklos Szeredi * method. 27422590e41SMiklos Szeredi */ 27522590e41SMiklos Szeredi if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode) && 27622590e41SMiklos Szeredi !(inode->i_mode & S_IXUGO)) 27722590e41SMiklos Szeredi return -EACCES; 27822590e41SMiklos Szeredi } 27922590e41SMiklos Szeredi } else { 2801da177e4SLinus Torvalds retval = generic_permission(inode, submask, NULL); 28122590e41SMiklos Szeredi } 2821da177e4SLinus Torvalds if (retval) 2831da177e4SLinus Torvalds return retval; 2841da177e4SLinus Torvalds 28508ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 28608ce5f16SSerge E. Hallyn if (retval) 28708ce5f16SSerge E. Hallyn return retval; 28808ce5f16SSerge E. Hallyn 2891da177e4SLinus Torvalds return security_inode_permission(inode, mask, nd); 2901da177e4SLinus Torvalds } 2911da177e4SLinus Torvalds 292e4543eddSChristoph Hellwig /** 293e4543eddSChristoph Hellwig * vfs_permission - check for access rights to a given path 294e4543eddSChristoph Hellwig * @nd: lookup result that describes the path 295e4543eddSChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 296e4543eddSChristoph Hellwig * 297e4543eddSChristoph Hellwig * Used to check for read/write/execute permissions on a path. 298e4543eddSChristoph Hellwig * We use "fsuid" for this, letting us set arbitrary permissions 299e4543eddSChristoph Hellwig * for filesystem access without changing the "normal" uids which 300e4543eddSChristoph Hellwig * are used for other things. 301e4543eddSChristoph Hellwig */ 302e4543eddSChristoph Hellwig int vfs_permission(struct nameidata *nd, int mask) 303e4543eddSChristoph Hellwig { 3044ac91378SJan Blunck return permission(nd->path.dentry->d_inode, mask, nd); 305e4543eddSChristoph Hellwig } 306e4543eddSChristoph Hellwig 3078c744fb8SChristoph Hellwig /** 3088c744fb8SChristoph Hellwig * file_permission - check for additional access rights to a given file 3098c744fb8SChristoph Hellwig * @file: file to check access rights for 3108c744fb8SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 3118c744fb8SChristoph Hellwig * 3128c744fb8SChristoph Hellwig * Used to check for read/write/execute permissions on an already opened 3138c744fb8SChristoph Hellwig * file. 3148c744fb8SChristoph Hellwig * 3158c744fb8SChristoph Hellwig * Note: 3168c744fb8SChristoph Hellwig * Do not use this function in new code. All access checks should 3178c744fb8SChristoph Hellwig * be done using vfs_permission(). 3188c744fb8SChristoph Hellwig */ 3198c744fb8SChristoph Hellwig int file_permission(struct file *file, int mask) 3208c744fb8SChristoph Hellwig { 3210f7fc9e4SJosef "Jeff" Sipek return permission(file->f_path.dentry->d_inode, mask, NULL); 3228c744fb8SChristoph Hellwig } 3238c744fb8SChristoph Hellwig 3241da177e4SLinus Torvalds /* 3251da177e4SLinus Torvalds * get_write_access() gets write permission for a file. 3261da177e4SLinus Torvalds * put_write_access() releases this write permission. 3271da177e4SLinus Torvalds * This is used for regular files. 3281da177e4SLinus Torvalds * We cannot support write (and maybe mmap read-write shared) accesses and 3291da177e4SLinus Torvalds * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode 3301da177e4SLinus Torvalds * can have the following values: 3311da177e4SLinus Torvalds * 0: no writers, no VM_DENYWRITE mappings 3321da177e4SLinus Torvalds * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist 3331da177e4SLinus Torvalds * > 0: (i_writecount) users are writing to the file. 3341da177e4SLinus Torvalds * 3351da177e4SLinus Torvalds * Normally we operate on that counter with atomic_{inc,dec} and it's safe 3361da177e4SLinus Torvalds * except for the cases where we don't hold i_writecount yet. Then we need to 3371da177e4SLinus Torvalds * use {get,deny}_write_access() - these functions check the sign and refuse 3381da177e4SLinus Torvalds * to do the change if sign is wrong. Exclusion between them is provided by 3391da177e4SLinus Torvalds * the inode->i_lock spinlock. 3401da177e4SLinus Torvalds */ 3411da177e4SLinus Torvalds 3421da177e4SLinus Torvalds int get_write_access(struct inode * inode) 3431da177e4SLinus Torvalds { 3441da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3451da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) < 0) { 3461da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3471da177e4SLinus Torvalds return -ETXTBSY; 3481da177e4SLinus Torvalds } 3491da177e4SLinus Torvalds atomic_inc(&inode->i_writecount); 3501da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3511da177e4SLinus Torvalds 3521da177e4SLinus Torvalds return 0; 3531da177e4SLinus Torvalds } 3541da177e4SLinus Torvalds 3551da177e4SLinus Torvalds int deny_write_access(struct file * file) 3561da177e4SLinus Torvalds { 3570f7fc9e4SJosef "Jeff" Sipek struct inode *inode = file->f_path.dentry->d_inode; 3581da177e4SLinus Torvalds 3591da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3601da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) > 0) { 3611da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3621da177e4SLinus Torvalds return -ETXTBSY; 3631da177e4SLinus Torvalds } 3641da177e4SLinus Torvalds atomic_dec(&inode->i_writecount); 3651da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3661da177e4SLinus Torvalds 3671da177e4SLinus Torvalds return 0; 3681da177e4SLinus Torvalds } 3691da177e4SLinus Torvalds 3701d957f9bSJan Blunck /** 3715dd784d0SJan Blunck * path_get - get a reference to a path 3725dd784d0SJan Blunck * @path: path to get the reference to 3735dd784d0SJan Blunck * 3745dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 3755dd784d0SJan Blunck */ 3765dd784d0SJan Blunck void path_get(struct path *path) 3775dd784d0SJan Blunck { 3785dd784d0SJan Blunck mntget(path->mnt); 3795dd784d0SJan Blunck dget(path->dentry); 3805dd784d0SJan Blunck } 3815dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 3825dd784d0SJan Blunck 3835dd784d0SJan Blunck /** 3841d957f9bSJan Blunck * path_put - put a reference to a path 3851d957f9bSJan Blunck * @path: path to put the reference to 3861d957f9bSJan Blunck * 3871d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 3881d957f9bSJan Blunck */ 3891d957f9bSJan Blunck void path_put(struct path *path) 3901da177e4SLinus Torvalds { 3911d957f9bSJan Blunck dput(path->dentry); 3921d957f9bSJan Blunck mntput(path->mnt); 3931da177e4SLinus Torvalds } 3941d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 3951da177e4SLinus Torvalds 396834f2a4aSTrond Myklebust /** 397834f2a4aSTrond Myklebust * release_open_intent - free up open intent resources 398834f2a4aSTrond Myklebust * @nd: pointer to nameidata 399834f2a4aSTrond Myklebust */ 400834f2a4aSTrond Myklebust void release_open_intent(struct nameidata *nd) 401834f2a4aSTrond Myklebust { 4020f7fc9e4SJosef "Jeff" Sipek if (nd->intent.open.file->f_path.dentry == NULL) 403834f2a4aSTrond Myklebust put_filp(nd->intent.open.file); 404834f2a4aSTrond Myklebust else 405834f2a4aSTrond Myklebust fput(nd->intent.open.file); 406834f2a4aSTrond Myklebust } 407834f2a4aSTrond Myklebust 408bcdc5e01SIan Kent static inline struct dentry * 409bcdc5e01SIan Kent do_revalidate(struct dentry *dentry, struct nameidata *nd) 410bcdc5e01SIan Kent { 411bcdc5e01SIan Kent int status = dentry->d_op->d_revalidate(dentry, nd); 412bcdc5e01SIan Kent if (unlikely(status <= 0)) { 413bcdc5e01SIan Kent /* 414bcdc5e01SIan Kent * The dentry failed validation. 415bcdc5e01SIan Kent * If d_revalidate returned 0 attempt to invalidate 416bcdc5e01SIan Kent * the dentry otherwise d_revalidate is asking us 417bcdc5e01SIan Kent * to return a fail status. 418bcdc5e01SIan Kent */ 419bcdc5e01SIan Kent if (!status) { 420bcdc5e01SIan Kent if (!d_invalidate(dentry)) { 421bcdc5e01SIan Kent dput(dentry); 422bcdc5e01SIan Kent dentry = NULL; 423bcdc5e01SIan Kent } 424bcdc5e01SIan Kent } else { 425bcdc5e01SIan Kent dput(dentry); 426bcdc5e01SIan Kent dentry = ERR_PTR(status); 427bcdc5e01SIan Kent } 428bcdc5e01SIan Kent } 429bcdc5e01SIan Kent return dentry; 430bcdc5e01SIan Kent } 431bcdc5e01SIan Kent 4321da177e4SLinus Torvalds /* 4331da177e4SLinus Torvalds * Internal lookup() using the new generic dcache. 4341da177e4SLinus Torvalds * SMP-safe 4351da177e4SLinus Torvalds */ 4361da177e4SLinus Torvalds static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) 4371da177e4SLinus Torvalds { 4381da177e4SLinus Torvalds struct dentry * dentry = __d_lookup(parent, name); 4391da177e4SLinus Torvalds 4401da177e4SLinus Torvalds /* lockess __d_lookup may fail due to concurrent d_move() 4411da177e4SLinus Torvalds * in some unrelated directory, so try with d_lookup 4421da177e4SLinus Torvalds */ 4431da177e4SLinus Torvalds if (!dentry) 4441da177e4SLinus Torvalds dentry = d_lookup(parent, name); 4451da177e4SLinus Torvalds 446bcdc5e01SIan Kent if (dentry && dentry->d_op && dentry->d_op->d_revalidate) 447bcdc5e01SIan Kent dentry = do_revalidate(dentry, nd); 448bcdc5e01SIan Kent 4491da177e4SLinus Torvalds return dentry; 4501da177e4SLinus Torvalds } 4511da177e4SLinus Torvalds 4521da177e4SLinus Torvalds /* 4531da177e4SLinus Torvalds * Short-cut version of permission(), for calling by 4541da177e4SLinus Torvalds * path_walk(), when dcache lock is held. Combines parts 4551da177e4SLinus Torvalds * of permission() and generic_permission(), and tests ONLY for 4561da177e4SLinus Torvalds * MAY_EXEC permission. 4571da177e4SLinus Torvalds * 4581da177e4SLinus Torvalds * If appropriate, check DAC only. If not appropriate, or 4591da177e4SLinus Torvalds * short-cut DAC fails, then call permission() to do more 4601da177e4SLinus Torvalds * complete permission check. 4611da177e4SLinus Torvalds */ 462858119e1SArjan van de Ven static int exec_permission_lite(struct inode *inode, 4631da177e4SLinus Torvalds struct nameidata *nd) 4641da177e4SLinus Torvalds { 4651da177e4SLinus Torvalds umode_t mode = inode->i_mode; 4661da177e4SLinus Torvalds 4671da177e4SLinus Torvalds if (inode->i_op && inode->i_op->permission) 4681da177e4SLinus Torvalds return -EAGAIN; 4691da177e4SLinus Torvalds 4701da177e4SLinus Torvalds if (current->fsuid == inode->i_uid) 4711da177e4SLinus Torvalds mode >>= 6; 4721da177e4SLinus Torvalds else if (in_group_p(inode->i_gid)) 4731da177e4SLinus Torvalds mode >>= 3; 4741da177e4SLinus Torvalds 4751da177e4SLinus Torvalds if (mode & MAY_EXEC) 4761da177e4SLinus Torvalds goto ok; 4771da177e4SLinus Torvalds 4781da177e4SLinus Torvalds if ((inode->i_mode & S_IXUGO) && capable(CAP_DAC_OVERRIDE)) 4791da177e4SLinus Torvalds goto ok; 4801da177e4SLinus Torvalds 4811da177e4SLinus Torvalds if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_OVERRIDE)) 4821da177e4SLinus Torvalds goto ok; 4831da177e4SLinus Torvalds 4841da177e4SLinus Torvalds if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_READ_SEARCH)) 4851da177e4SLinus Torvalds goto ok; 4861da177e4SLinus Torvalds 4871da177e4SLinus Torvalds return -EACCES; 4881da177e4SLinus Torvalds ok: 4891da177e4SLinus Torvalds return security_inode_permission(inode, MAY_EXEC, nd); 4901da177e4SLinus Torvalds } 4911da177e4SLinus Torvalds 4921da177e4SLinus Torvalds /* 4931da177e4SLinus Torvalds * This is called when everything else fails, and we actually have 4941da177e4SLinus Torvalds * to go to the low-level filesystem to find out what we should do.. 4951da177e4SLinus Torvalds * 4961da177e4SLinus Torvalds * We get the directory semaphore, and after getting that we also 4971da177e4SLinus Torvalds * make sure that nobody added the entry to the dcache in the meantime.. 4981da177e4SLinus Torvalds * SMP-safe 4991da177e4SLinus Torvalds */ 5001da177e4SLinus Torvalds static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) 5011da177e4SLinus Torvalds { 5021da177e4SLinus Torvalds struct dentry * result; 5031da177e4SLinus Torvalds struct inode *dir = parent->d_inode; 5041da177e4SLinus Torvalds 5051b1dcc1bSJes Sorensen mutex_lock(&dir->i_mutex); 5061da177e4SLinus Torvalds /* 5071da177e4SLinus Torvalds * First re-do the cached lookup just in case it was created 5081da177e4SLinus Torvalds * while we waited for the directory semaphore.. 5091da177e4SLinus Torvalds * 5101da177e4SLinus Torvalds * FIXME! This could use version numbering or similar to 5111da177e4SLinus Torvalds * avoid unnecessary cache lookups. 5121da177e4SLinus Torvalds * 5131da177e4SLinus Torvalds * The "dcache_lock" is purely to protect the RCU list walker 5141da177e4SLinus Torvalds * from concurrent renames at this point (we mustn't get false 5151da177e4SLinus Torvalds * negatives from the RCU list walk here, unlike the optimistic 5161da177e4SLinus Torvalds * fast walk). 5171da177e4SLinus Torvalds * 5181da177e4SLinus Torvalds * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup 5191da177e4SLinus Torvalds */ 5201da177e4SLinus Torvalds result = d_lookup(parent, name); 5211da177e4SLinus Torvalds if (!result) { 5221da177e4SLinus Torvalds struct dentry * dentry = d_alloc(parent, name); 5231da177e4SLinus Torvalds result = ERR_PTR(-ENOMEM); 5241da177e4SLinus Torvalds if (dentry) { 5251da177e4SLinus Torvalds result = dir->i_op->lookup(dir, dentry, nd); 5261da177e4SLinus Torvalds if (result) 5271da177e4SLinus Torvalds dput(dentry); 5281da177e4SLinus Torvalds else 5291da177e4SLinus Torvalds result = dentry; 5301da177e4SLinus Torvalds } 5311b1dcc1bSJes Sorensen mutex_unlock(&dir->i_mutex); 5321da177e4SLinus Torvalds return result; 5331da177e4SLinus Torvalds } 5341da177e4SLinus Torvalds 5351da177e4SLinus Torvalds /* 5361da177e4SLinus Torvalds * Uhhuh! Nasty case: the cache was re-populated while 5371da177e4SLinus Torvalds * we waited on the semaphore. Need to revalidate. 5381da177e4SLinus Torvalds */ 5391b1dcc1bSJes Sorensen mutex_unlock(&dir->i_mutex); 5401da177e4SLinus Torvalds if (result->d_op && result->d_op->d_revalidate) { 541bcdc5e01SIan Kent result = do_revalidate(result, nd); 542bcdc5e01SIan Kent if (!result) 5431da177e4SLinus Torvalds result = ERR_PTR(-ENOENT); 5441da177e4SLinus Torvalds } 5451da177e4SLinus Torvalds return result; 5461da177e4SLinus Torvalds } 5471da177e4SLinus Torvalds 5481da177e4SLinus Torvalds static int __emul_lookup_dentry(const char *, struct nameidata *); 5491da177e4SLinus Torvalds 5501da177e4SLinus Torvalds /* SMP-safe */ 551f1662356SArjan van de Ven static __always_inline int 5521da177e4SLinus Torvalds walk_init_root(const char *name, struct nameidata *nd) 5531da177e4SLinus Torvalds { 554e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 555e518ddb7SAndreas Mohr 556e518ddb7SAndreas Mohr read_lock(&fs->lock); 5576ac08c39SJan Blunck if (fs->altroot.dentry && !(nd->flags & LOOKUP_NOALT)) { 5586ac08c39SJan Blunck nd->path = fs->altroot; 5596ac08c39SJan Blunck path_get(&fs->altroot); 560e518ddb7SAndreas Mohr read_unlock(&fs->lock); 5611da177e4SLinus Torvalds if (__emul_lookup_dentry(name,nd)) 5621da177e4SLinus Torvalds return 0; 563e518ddb7SAndreas Mohr read_lock(&fs->lock); 5641da177e4SLinus Torvalds } 5656ac08c39SJan Blunck nd->path = fs->root; 5666ac08c39SJan Blunck path_get(&fs->root); 567e518ddb7SAndreas Mohr read_unlock(&fs->lock); 5681da177e4SLinus Torvalds return 1; 5691da177e4SLinus Torvalds } 5701da177e4SLinus Torvalds 571a02f76c3SAl Viro /* 572a02f76c3SAl Viro * Wrapper to retry pathname resolution whenever the underlying 573a02f76c3SAl Viro * file system returns an ESTALE. 574a02f76c3SAl Viro * 575a02f76c3SAl Viro * Retry the whole path once, forcing real lookup requests 576a02f76c3SAl Viro * instead of relying on the dcache. 577a02f76c3SAl Viro */ 578a02f76c3SAl Viro static __always_inline int link_path_walk(const char *name, struct nameidata *nd) 579a02f76c3SAl Viro { 580a02f76c3SAl Viro struct path save = nd->path; 581a02f76c3SAl Viro int result; 582a02f76c3SAl Viro 583a02f76c3SAl Viro /* make sure the stuff we saved doesn't go away */ 584a02f76c3SAl Viro dget(save.dentry); 585a02f76c3SAl Viro mntget(save.mnt); 586a02f76c3SAl Viro 587a02f76c3SAl Viro result = __link_path_walk(name, nd); 588a02f76c3SAl Viro if (result == -ESTALE) { 589a02f76c3SAl Viro /* nd->path had been dropped */ 590a02f76c3SAl Viro nd->path = save; 591a02f76c3SAl Viro dget(nd->path.dentry); 592a02f76c3SAl Viro mntget(nd->path.mnt); 593a02f76c3SAl Viro nd->flags |= LOOKUP_REVAL; 594a02f76c3SAl Viro result = __link_path_walk(name, nd); 595a02f76c3SAl Viro } 596a02f76c3SAl Viro 597a02f76c3SAl Viro path_put(&save); 598a02f76c3SAl Viro 599a02f76c3SAl Viro return result; 600a02f76c3SAl Viro } 601a02f76c3SAl Viro 602f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 6031da177e4SLinus Torvalds { 6041da177e4SLinus Torvalds int res = 0; 6051da177e4SLinus Torvalds char *name; 6061da177e4SLinus Torvalds if (IS_ERR(link)) 6071da177e4SLinus Torvalds goto fail; 6081da177e4SLinus Torvalds 6091da177e4SLinus Torvalds if (*link == '/') { 6101d957f9bSJan Blunck path_put(&nd->path); 6111da177e4SLinus Torvalds if (!walk_init_root(link, nd)) 6121da177e4SLinus Torvalds /* weird __emul_prefix() stuff did it */ 6131da177e4SLinus Torvalds goto out; 6141da177e4SLinus Torvalds } 6151da177e4SLinus Torvalds res = link_path_walk(link, nd); 6161da177e4SLinus Torvalds out: 6171da177e4SLinus Torvalds if (nd->depth || res || nd->last_type!=LAST_NORM) 6181da177e4SLinus Torvalds return res; 6191da177e4SLinus Torvalds /* 6201da177e4SLinus Torvalds * If it is an iterative symlinks resolution in open_namei() we 6211da177e4SLinus Torvalds * have to copy the last component. And all that crap because of 6221da177e4SLinus Torvalds * bloody create() on broken symlinks. Furrfu... 6231da177e4SLinus Torvalds */ 6241da177e4SLinus Torvalds name = __getname(); 6251da177e4SLinus Torvalds if (unlikely(!name)) { 6261d957f9bSJan Blunck path_put(&nd->path); 6271da177e4SLinus Torvalds return -ENOMEM; 6281da177e4SLinus Torvalds } 6291da177e4SLinus Torvalds strcpy(name, nd->last.name); 6301da177e4SLinus Torvalds nd->last.name = name; 6311da177e4SLinus Torvalds return 0; 6321da177e4SLinus Torvalds fail: 6331d957f9bSJan Blunck path_put(&nd->path); 6341da177e4SLinus Torvalds return PTR_ERR(link); 6351da177e4SLinus Torvalds } 6361da177e4SLinus Torvalds 6371d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 638051d3812SIan Kent { 639051d3812SIan Kent dput(path->dentry); 6404ac91378SJan Blunck if (path->mnt != nd->path.mnt) 641051d3812SIan Kent mntput(path->mnt); 642051d3812SIan Kent } 643051d3812SIan Kent 644051d3812SIan Kent static inline void path_to_nameidata(struct path *path, struct nameidata *nd) 645051d3812SIan Kent { 6464ac91378SJan Blunck dput(nd->path.dentry); 6474ac91378SJan Blunck if (nd->path.mnt != path->mnt) 6484ac91378SJan Blunck mntput(nd->path.mnt); 6494ac91378SJan Blunck nd->path.mnt = path->mnt; 6504ac91378SJan Blunck nd->path.dentry = path->dentry; 651051d3812SIan Kent } 652051d3812SIan Kent 653f1662356SArjan van de Ven static __always_inline int __do_follow_link(struct path *path, struct nameidata *nd) 6541da177e4SLinus Torvalds { 6551da177e4SLinus Torvalds int error; 656cc314eefSLinus Torvalds void *cookie; 657cd4e91d3SAl Viro struct dentry *dentry = path->dentry; 6581da177e4SLinus Torvalds 659d671a1cbSAl Viro touch_atime(path->mnt, dentry); 6601da177e4SLinus Torvalds nd_set_link(nd, NULL); 661cd4e91d3SAl Viro 6624ac91378SJan Blunck if (path->mnt != nd->path.mnt) { 663051d3812SIan Kent path_to_nameidata(path, nd); 664051d3812SIan Kent dget(dentry); 665051d3812SIan Kent } 666cd4e91d3SAl Viro mntget(path->mnt); 667cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, nd); 668cc314eefSLinus Torvalds error = PTR_ERR(cookie); 669cc314eefSLinus Torvalds if (!IS_ERR(cookie)) { 6701da177e4SLinus Torvalds char *s = nd_get_link(nd); 671cc314eefSLinus Torvalds error = 0; 6721da177e4SLinus Torvalds if (s) 6731da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 6741da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 675cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, nd, cookie); 6761da177e4SLinus Torvalds } 67709da5916SJan Blunck path_put(path); 6781da177e4SLinus Torvalds 6791da177e4SLinus Torvalds return error; 6801da177e4SLinus Torvalds } 6811da177e4SLinus Torvalds 6821da177e4SLinus Torvalds /* 6831da177e4SLinus Torvalds * This limits recursive symlink follows to 8, while 6841da177e4SLinus Torvalds * limiting consecutive symlinks to 40. 6851da177e4SLinus Torvalds * 6861da177e4SLinus Torvalds * Without that kind of total limit, nasty chains of consecutive 6871da177e4SLinus Torvalds * symlinks can cause almost arbitrarily long lookups. 6881da177e4SLinus Torvalds */ 68990ebe565SAl Viro static inline int do_follow_link(struct path *path, struct nameidata *nd) 6901da177e4SLinus Torvalds { 6911da177e4SLinus Torvalds int err = -ELOOP; 6921da177e4SLinus Torvalds if (current->link_count >= MAX_NESTED_LINKS) 6931da177e4SLinus Torvalds goto loop; 6941da177e4SLinus Torvalds if (current->total_link_count >= 40) 6951da177e4SLinus Torvalds goto loop; 6961da177e4SLinus Torvalds BUG_ON(nd->depth >= MAX_NESTED_LINKS); 6971da177e4SLinus Torvalds cond_resched(); 69890ebe565SAl Viro err = security_inode_follow_link(path->dentry, nd); 6991da177e4SLinus Torvalds if (err) 7001da177e4SLinus Torvalds goto loop; 7011da177e4SLinus Torvalds current->link_count++; 7021da177e4SLinus Torvalds current->total_link_count++; 7031da177e4SLinus Torvalds nd->depth++; 704cd4e91d3SAl Viro err = __do_follow_link(path, nd); 7051da177e4SLinus Torvalds current->link_count--; 7061da177e4SLinus Torvalds nd->depth--; 7071da177e4SLinus Torvalds return err; 7081da177e4SLinus Torvalds loop: 7091d957f9bSJan Blunck path_put_conditional(path, nd); 7101d957f9bSJan Blunck path_put(&nd->path); 7111da177e4SLinus Torvalds return err; 7121da177e4SLinus Torvalds } 7131da177e4SLinus Torvalds 7141da177e4SLinus Torvalds int follow_up(struct vfsmount **mnt, struct dentry **dentry) 7151da177e4SLinus Torvalds { 7161da177e4SLinus Torvalds struct vfsmount *parent; 7171da177e4SLinus Torvalds struct dentry *mountpoint; 7181da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 7191da177e4SLinus Torvalds parent=(*mnt)->mnt_parent; 7201da177e4SLinus Torvalds if (parent == *mnt) { 7211da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7221da177e4SLinus Torvalds return 0; 7231da177e4SLinus Torvalds } 7241da177e4SLinus Torvalds mntget(parent); 7251da177e4SLinus Torvalds mountpoint=dget((*mnt)->mnt_mountpoint); 7261da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7271da177e4SLinus Torvalds dput(*dentry); 7281da177e4SLinus Torvalds *dentry = mountpoint; 7291da177e4SLinus Torvalds mntput(*mnt); 7301da177e4SLinus Torvalds *mnt = parent; 7311da177e4SLinus Torvalds return 1; 7321da177e4SLinus Torvalds } 7331da177e4SLinus Torvalds 7341da177e4SLinus Torvalds /* no need for dcache_lock, as serialization is taken care in 7351da177e4SLinus Torvalds * namespace.c 7361da177e4SLinus Torvalds */ 737463ffb2eSAl Viro static int __follow_mount(struct path *path) 738463ffb2eSAl Viro { 739463ffb2eSAl Viro int res = 0; 740463ffb2eSAl Viro while (d_mountpoint(path->dentry)) { 741463ffb2eSAl Viro struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry); 742463ffb2eSAl Viro if (!mounted) 743463ffb2eSAl Viro break; 744463ffb2eSAl Viro dput(path->dentry); 745463ffb2eSAl Viro if (res) 746463ffb2eSAl Viro mntput(path->mnt); 747463ffb2eSAl Viro path->mnt = mounted; 748463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 749463ffb2eSAl Viro res = 1; 750463ffb2eSAl Viro } 751463ffb2eSAl Viro return res; 752463ffb2eSAl Viro } 753463ffb2eSAl Viro 75458c465ebSAl Viro static void follow_mount(struct vfsmount **mnt, struct dentry **dentry) 7551da177e4SLinus Torvalds { 7561da177e4SLinus Torvalds while (d_mountpoint(*dentry)) { 7571da177e4SLinus Torvalds struct vfsmount *mounted = lookup_mnt(*mnt, *dentry); 7581da177e4SLinus Torvalds if (!mounted) 7591da177e4SLinus Torvalds break; 76058c465ebSAl Viro dput(*dentry); 7611da177e4SLinus Torvalds mntput(*mnt); 7621da177e4SLinus Torvalds *mnt = mounted; 7631da177e4SLinus Torvalds *dentry = dget(mounted->mnt_root); 7641da177e4SLinus Torvalds } 7651da177e4SLinus Torvalds } 7661da177e4SLinus Torvalds 7671da177e4SLinus Torvalds /* no need for dcache_lock, as serialization is taken care in 7681da177e4SLinus Torvalds * namespace.c 7691da177e4SLinus Torvalds */ 770e13b210fSAl Viro int follow_down(struct vfsmount **mnt, struct dentry **dentry) 7711da177e4SLinus Torvalds { 7721da177e4SLinus Torvalds struct vfsmount *mounted; 7731da177e4SLinus Torvalds 7741da177e4SLinus Torvalds mounted = lookup_mnt(*mnt, *dentry); 7751da177e4SLinus Torvalds if (mounted) { 776e13b210fSAl Viro dput(*dentry); 7771da177e4SLinus Torvalds mntput(*mnt); 7781da177e4SLinus Torvalds *mnt = mounted; 7791da177e4SLinus Torvalds *dentry = dget(mounted->mnt_root); 7801da177e4SLinus Torvalds return 1; 7811da177e4SLinus Torvalds } 7821da177e4SLinus Torvalds return 0; 7831da177e4SLinus Torvalds } 7841da177e4SLinus Torvalds 785f1662356SArjan van de Ven static __always_inline void follow_dotdot(struct nameidata *nd) 7861da177e4SLinus Torvalds { 787e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 788e518ddb7SAndreas Mohr 7891da177e4SLinus Torvalds while(1) { 7901da177e4SLinus Torvalds struct vfsmount *parent; 7914ac91378SJan Blunck struct dentry *old = nd->path.dentry; 7921da177e4SLinus Torvalds 793e518ddb7SAndreas Mohr read_lock(&fs->lock); 7946ac08c39SJan Blunck if (nd->path.dentry == fs->root.dentry && 7956ac08c39SJan Blunck nd->path.mnt == fs->root.mnt) { 796e518ddb7SAndreas Mohr read_unlock(&fs->lock); 7971da177e4SLinus Torvalds break; 7981da177e4SLinus Torvalds } 799e518ddb7SAndreas Mohr read_unlock(&fs->lock); 8001da177e4SLinus Torvalds spin_lock(&dcache_lock); 8014ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 8024ac91378SJan Blunck nd->path.dentry = dget(nd->path.dentry->d_parent); 8031da177e4SLinus Torvalds spin_unlock(&dcache_lock); 8041da177e4SLinus Torvalds dput(old); 8051da177e4SLinus Torvalds break; 8061da177e4SLinus Torvalds } 8071da177e4SLinus Torvalds spin_unlock(&dcache_lock); 8081da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 8094ac91378SJan Blunck parent = nd->path.mnt->mnt_parent; 8104ac91378SJan Blunck if (parent == nd->path.mnt) { 8111da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 8121da177e4SLinus Torvalds break; 8131da177e4SLinus Torvalds } 8141da177e4SLinus Torvalds mntget(parent); 8154ac91378SJan Blunck nd->path.dentry = dget(nd->path.mnt->mnt_mountpoint); 8161da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 8171da177e4SLinus Torvalds dput(old); 8184ac91378SJan Blunck mntput(nd->path.mnt); 8194ac91378SJan Blunck nd->path.mnt = parent; 8201da177e4SLinus Torvalds } 8214ac91378SJan Blunck follow_mount(&nd->path.mnt, &nd->path.dentry); 8221da177e4SLinus Torvalds } 8231da177e4SLinus Torvalds 8241da177e4SLinus Torvalds /* 8251da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 8261da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 8271da177e4SLinus Torvalds * It _is_ time-critical. 8281da177e4SLinus Torvalds */ 8291da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 8301da177e4SLinus Torvalds struct path *path) 8311da177e4SLinus Torvalds { 8324ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 8334ac91378SJan Blunck struct dentry *dentry = __d_lookup(nd->path.dentry, name); 8341da177e4SLinus Torvalds 8351da177e4SLinus Torvalds if (!dentry) 8361da177e4SLinus Torvalds goto need_lookup; 8371da177e4SLinus Torvalds if (dentry->d_op && dentry->d_op->d_revalidate) 8381da177e4SLinus Torvalds goto need_revalidate; 8391da177e4SLinus Torvalds done: 8401da177e4SLinus Torvalds path->mnt = mnt; 8411da177e4SLinus Torvalds path->dentry = dentry; 842634ee701SAl Viro __follow_mount(path); 8431da177e4SLinus Torvalds return 0; 8441da177e4SLinus Torvalds 8451da177e4SLinus Torvalds need_lookup: 8464ac91378SJan Blunck dentry = real_lookup(nd->path.dentry, name, nd); 8471da177e4SLinus Torvalds if (IS_ERR(dentry)) 8481da177e4SLinus Torvalds goto fail; 8491da177e4SLinus Torvalds goto done; 8501da177e4SLinus Torvalds 8511da177e4SLinus Torvalds need_revalidate: 852bcdc5e01SIan Kent dentry = do_revalidate(dentry, nd); 853bcdc5e01SIan Kent if (!dentry) 8541da177e4SLinus Torvalds goto need_lookup; 855bcdc5e01SIan Kent if (IS_ERR(dentry)) 856bcdc5e01SIan Kent goto fail; 857bcdc5e01SIan Kent goto done; 8581da177e4SLinus Torvalds 8591da177e4SLinus Torvalds fail: 8601da177e4SLinus Torvalds return PTR_ERR(dentry); 8611da177e4SLinus Torvalds } 8621da177e4SLinus Torvalds 8631da177e4SLinus Torvalds /* 8641da177e4SLinus Torvalds * Name resolution. 865ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 866ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 8671da177e4SLinus Torvalds * 868ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 869ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 8701da177e4SLinus Torvalds */ 871fc9b52cdSHarvey Harrison static int __link_path_walk(const char *name, struct nameidata *nd) 8721da177e4SLinus Torvalds { 8731da177e4SLinus Torvalds struct path next; 8741da177e4SLinus Torvalds struct inode *inode; 8751da177e4SLinus Torvalds int err; 8761da177e4SLinus Torvalds unsigned int lookup_flags = nd->flags; 8771da177e4SLinus Torvalds 8781da177e4SLinus Torvalds while (*name=='/') 8791da177e4SLinus Torvalds name++; 8801da177e4SLinus Torvalds if (!*name) 8811da177e4SLinus Torvalds goto return_reval; 8821da177e4SLinus Torvalds 8834ac91378SJan Blunck inode = nd->path.dentry->d_inode; 8841da177e4SLinus Torvalds if (nd->depth) 885f55eab82STrond Myklebust lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE); 8861da177e4SLinus Torvalds 8871da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 8881da177e4SLinus Torvalds for(;;) { 8891da177e4SLinus Torvalds unsigned long hash; 8901da177e4SLinus Torvalds struct qstr this; 8911da177e4SLinus Torvalds unsigned int c; 8921da177e4SLinus Torvalds 893cdce5d6bSTrond Myklebust nd->flags |= LOOKUP_CONTINUE; 8941da177e4SLinus Torvalds err = exec_permission_lite(inode, nd); 895e4543eddSChristoph Hellwig if (err == -EAGAIN) 896e4543eddSChristoph Hellwig err = vfs_permission(nd, MAY_EXEC); 8971da177e4SLinus Torvalds if (err) 8981da177e4SLinus Torvalds break; 8991da177e4SLinus Torvalds 9001da177e4SLinus Torvalds this.name = name; 9011da177e4SLinus Torvalds c = *(const unsigned char *)name; 9021da177e4SLinus Torvalds 9031da177e4SLinus Torvalds hash = init_name_hash(); 9041da177e4SLinus Torvalds do { 9051da177e4SLinus Torvalds name++; 9061da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 9071da177e4SLinus Torvalds c = *(const unsigned char *)name; 9081da177e4SLinus Torvalds } while (c && (c != '/')); 9091da177e4SLinus Torvalds this.len = name - (const char *) this.name; 9101da177e4SLinus Torvalds this.hash = end_name_hash(hash); 9111da177e4SLinus Torvalds 9121da177e4SLinus Torvalds /* remove trailing slashes? */ 9131da177e4SLinus Torvalds if (!c) 9141da177e4SLinus Torvalds goto last_component; 9151da177e4SLinus Torvalds while (*++name == '/'); 9161da177e4SLinus Torvalds if (!*name) 9171da177e4SLinus Torvalds goto last_with_slashes; 9181da177e4SLinus Torvalds 9191da177e4SLinus Torvalds /* 9201da177e4SLinus Torvalds * "." and ".." are special - ".." especially so because it has 9211da177e4SLinus Torvalds * to be able to know about the current root directory and 9221da177e4SLinus Torvalds * parent relationships. 9231da177e4SLinus Torvalds */ 9241da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 9251da177e4SLinus Torvalds default: 9261da177e4SLinus Torvalds break; 9271da177e4SLinus Torvalds case 2: 9281da177e4SLinus Torvalds if (this.name[1] != '.') 9291da177e4SLinus Torvalds break; 93058c465ebSAl Viro follow_dotdot(nd); 9314ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9321da177e4SLinus Torvalds /* fallthrough */ 9331da177e4SLinus Torvalds case 1: 9341da177e4SLinus Torvalds continue; 9351da177e4SLinus Torvalds } 9361da177e4SLinus Torvalds /* 9371da177e4SLinus Torvalds * See if the low-level filesystem might want 9381da177e4SLinus Torvalds * to use its own hash.. 9391da177e4SLinus Torvalds */ 9404ac91378SJan Blunck if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { 9414ac91378SJan Blunck err = nd->path.dentry->d_op->d_hash(nd->path.dentry, 9424ac91378SJan Blunck &this); 9431da177e4SLinus Torvalds if (err < 0) 9441da177e4SLinus Torvalds break; 9451da177e4SLinus Torvalds } 9461da177e4SLinus Torvalds /* This does the actual lookups.. */ 9471da177e4SLinus Torvalds err = do_lookup(nd, &this, &next); 9481da177e4SLinus Torvalds if (err) 9491da177e4SLinus Torvalds break; 9501da177e4SLinus Torvalds 9511da177e4SLinus Torvalds err = -ENOENT; 9521da177e4SLinus Torvalds inode = next.dentry->d_inode; 9531da177e4SLinus Torvalds if (!inode) 9541da177e4SLinus Torvalds goto out_dput; 9551da177e4SLinus Torvalds err = -ENOTDIR; 9561da177e4SLinus Torvalds if (!inode->i_op) 9571da177e4SLinus Torvalds goto out_dput; 9581da177e4SLinus Torvalds 9591da177e4SLinus Torvalds if (inode->i_op->follow_link) { 96090ebe565SAl Viro err = do_follow_link(&next, nd); 9611da177e4SLinus Torvalds if (err) 9621da177e4SLinus Torvalds goto return_err; 9631da177e4SLinus Torvalds err = -ENOENT; 9644ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9651da177e4SLinus Torvalds if (!inode) 9661da177e4SLinus Torvalds break; 9671da177e4SLinus Torvalds err = -ENOTDIR; 9681da177e4SLinus Torvalds if (!inode->i_op) 9691da177e4SLinus Torvalds break; 97009dd17d3SMiklos Szeredi } else 97109dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 9721da177e4SLinus Torvalds err = -ENOTDIR; 9731da177e4SLinus Torvalds if (!inode->i_op->lookup) 9741da177e4SLinus Torvalds break; 9751da177e4SLinus Torvalds continue; 9761da177e4SLinus Torvalds /* here ends the main loop */ 9771da177e4SLinus Torvalds 9781da177e4SLinus Torvalds last_with_slashes: 9791da177e4SLinus Torvalds lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 9801da177e4SLinus Torvalds last_component: 981f55eab82STrond Myklebust /* Clear LOOKUP_CONTINUE iff it was previously unset */ 982f55eab82STrond Myklebust nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; 9831da177e4SLinus Torvalds if (lookup_flags & LOOKUP_PARENT) 9841da177e4SLinus Torvalds goto lookup_parent; 9851da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 9861da177e4SLinus Torvalds default: 9871da177e4SLinus Torvalds break; 9881da177e4SLinus Torvalds case 2: 9891da177e4SLinus Torvalds if (this.name[1] != '.') 9901da177e4SLinus Torvalds break; 99158c465ebSAl Viro follow_dotdot(nd); 9924ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9931da177e4SLinus Torvalds /* fallthrough */ 9941da177e4SLinus Torvalds case 1: 9951da177e4SLinus Torvalds goto return_reval; 9961da177e4SLinus Torvalds } 9974ac91378SJan Blunck if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { 9984ac91378SJan Blunck err = nd->path.dentry->d_op->d_hash(nd->path.dentry, 9994ac91378SJan Blunck &this); 10001da177e4SLinus Torvalds if (err < 0) 10011da177e4SLinus Torvalds break; 10021da177e4SLinus Torvalds } 10031da177e4SLinus Torvalds err = do_lookup(nd, &this, &next); 10041da177e4SLinus Torvalds if (err) 10051da177e4SLinus Torvalds break; 10061da177e4SLinus Torvalds inode = next.dentry->d_inode; 10071da177e4SLinus Torvalds if ((lookup_flags & LOOKUP_FOLLOW) 10081da177e4SLinus Torvalds && inode && inode->i_op && inode->i_op->follow_link) { 100990ebe565SAl Viro err = do_follow_link(&next, nd); 10101da177e4SLinus Torvalds if (err) 10111da177e4SLinus Torvalds goto return_err; 10124ac91378SJan Blunck inode = nd->path.dentry->d_inode; 101309dd17d3SMiklos Szeredi } else 101409dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 10151da177e4SLinus Torvalds err = -ENOENT; 10161da177e4SLinus Torvalds if (!inode) 10171da177e4SLinus Torvalds break; 10181da177e4SLinus Torvalds if (lookup_flags & LOOKUP_DIRECTORY) { 10191da177e4SLinus Torvalds err = -ENOTDIR; 10201da177e4SLinus Torvalds if (!inode->i_op || !inode->i_op->lookup) 10211da177e4SLinus Torvalds break; 10221da177e4SLinus Torvalds } 10231da177e4SLinus Torvalds goto return_base; 10241da177e4SLinus Torvalds lookup_parent: 10251da177e4SLinus Torvalds nd->last = this; 10261da177e4SLinus Torvalds nd->last_type = LAST_NORM; 10271da177e4SLinus Torvalds if (this.name[0] != '.') 10281da177e4SLinus Torvalds goto return_base; 10291da177e4SLinus Torvalds if (this.len == 1) 10301da177e4SLinus Torvalds nd->last_type = LAST_DOT; 10311da177e4SLinus Torvalds else if (this.len == 2 && this.name[1] == '.') 10321da177e4SLinus Torvalds nd->last_type = LAST_DOTDOT; 10331da177e4SLinus Torvalds else 10341da177e4SLinus Torvalds goto return_base; 10351da177e4SLinus Torvalds return_reval: 10361da177e4SLinus Torvalds /* 10371da177e4SLinus Torvalds * We bypassed the ordinary revalidation routines. 10381da177e4SLinus Torvalds * We may need to check the cached dentry for staleness. 10391da177e4SLinus Torvalds */ 10404ac91378SJan Blunck if (nd->path.dentry && nd->path.dentry->d_sb && 10414ac91378SJan Blunck (nd->path.dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) { 10421da177e4SLinus Torvalds err = -ESTALE; 10431da177e4SLinus Torvalds /* Note: we do not d_invalidate() */ 10444ac91378SJan Blunck if (!nd->path.dentry->d_op->d_revalidate( 10454ac91378SJan Blunck nd->path.dentry, nd)) 10461da177e4SLinus Torvalds break; 10471da177e4SLinus Torvalds } 10481da177e4SLinus Torvalds return_base: 10491da177e4SLinus Torvalds return 0; 10501da177e4SLinus Torvalds out_dput: 10511d957f9bSJan Blunck path_put_conditional(&next, nd); 10521da177e4SLinus Torvalds break; 10531da177e4SLinus Torvalds } 10541d957f9bSJan Blunck path_put(&nd->path); 10551da177e4SLinus Torvalds return_err: 10561da177e4SLinus Torvalds return err; 10571da177e4SLinus Torvalds } 10581da177e4SLinus Torvalds 1059fc9b52cdSHarvey Harrison static int path_walk(const char *name, struct nameidata *nd) 10601da177e4SLinus Torvalds { 10611da177e4SLinus Torvalds current->total_link_count = 0; 10621da177e4SLinus Torvalds return link_path_walk(name, nd); 10631da177e4SLinus Torvalds } 10641da177e4SLinus Torvalds 1065ea3834d9SPrasanna Meda /* 1066ea3834d9SPrasanna Meda * SMP-safe: Returns 1 and nd will have valid dentry and mnt, if 1067ea3834d9SPrasanna Meda * everything is done. Returns 0 and drops input nd, if lookup failed; 1068ea3834d9SPrasanna Meda */ 10691da177e4SLinus Torvalds static int __emul_lookup_dentry(const char *name, struct nameidata *nd) 10701da177e4SLinus Torvalds { 10711da177e4SLinus Torvalds if (path_walk(name, nd)) 10721da177e4SLinus Torvalds return 0; /* something went wrong... */ 10731da177e4SLinus Torvalds 10744ac91378SJan Blunck if (!nd->path.dentry->d_inode || 10754ac91378SJan Blunck S_ISDIR(nd->path.dentry->d_inode->i_mode)) { 107609da5916SJan Blunck struct path old_path = nd->path; 10771da177e4SLinus Torvalds struct qstr last = nd->last; 10781da177e4SLinus Torvalds int last_type = nd->last_type; 1079e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 1080e518ddb7SAndreas Mohr 10811da177e4SLinus Torvalds /* 1082e518ddb7SAndreas Mohr * NAME was not found in alternate root or it's a directory. 1083e518ddb7SAndreas Mohr * Try to find it in the normal root: 10841da177e4SLinus Torvalds */ 10851da177e4SLinus Torvalds nd->last_type = LAST_ROOT; 1086e518ddb7SAndreas Mohr read_lock(&fs->lock); 10876ac08c39SJan Blunck nd->path = fs->root; 10886ac08c39SJan Blunck path_get(&fs->root); 1089e518ddb7SAndreas Mohr read_unlock(&fs->lock); 10901da177e4SLinus Torvalds if (path_walk(name, nd) == 0) { 10914ac91378SJan Blunck if (nd->path.dentry->d_inode) { 109209da5916SJan Blunck path_put(&old_path); 10931da177e4SLinus Torvalds return 1; 10941da177e4SLinus Torvalds } 10951d957f9bSJan Blunck path_put(&nd->path); 10961da177e4SLinus Torvalds } 109709da5916SJan Blunck nd->path = old_path; 10981da177e4SLinus Torvalds nd->last = last; 10991da177e4SLinus Torvalds nd->last_type = last_type; 11001da177e4SLinus Torvalds } 11011da177e4SLinus Torvalds return 1; 11021da177e4SLinus Torvalds } 11031da177e4SLinus Torvalds 11041da177e4SLinus Torvalds void set_fs_altroot(void) 11051da177e4SLinus Torvalds { 11061da177e4SLinus Torvalds char *emul = __emul_prefix(); 11071da177e4SLinus Torvalds struct nameidata nd; 11086ac08c39SJan Blunck struct path path = {}, old_path; 11091da177e4SLinus Torvalds int err; 1110e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 11111da177e4SLinus Torvalds 11121da177e4SLinus Torvalds if (!emul) 11131da177e4SLinus Torvalds goto set_it; 11141da177e4SLinus Torvalds err = path_lookup(emul, LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_NOALT, &nd); 11156ac08c39SJan Blunck if (!err) 11166ac08c39SJan Blunck path = nd.path; 11171da177e4SLinus Torvalds set_it: 1118e518ddb7SAndreas Mohr write_lock(&fs->lock); 11196ac08c39SJan Blunck old_path = fs->altroot; 11206ac08c39SJan Blunck fs->altroot = path; 1121e518ddb7SAndreas Mohr write_unlock(&fs->lock); 11226ac08c39SJan Blunck if (old_path.dentry) 11236ac08c39SJan Blunck path_put(&old_path); 11241da177e4SLinus Torvalds } 11251da177e4SLinus Torvalds 1126ea3834d9SPrasanna Meda /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1127fc9b52cdSHarvey Harrison static int do_path_lookup(int dfd, const char *name, 11285590ff0dSUlrich Drepper unsigned int flags, struct nameidata *nd) 11291da177e4SLinus Torvalds { 1130ea3834d9SPrasanna Meda int retval = 0; 1131170aa3d0SUlrich Drepper int fput_needed; 1132170aa3d0SUlrich Drepper struct file *file; 1133e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 11341da177e4SLinus Torvalds 11351da177e4SLinus Torvalds nd->last_type = LAST_ROOT; /* if there are only slashes... */ 11361da177e4SLinus Torvalds nd->flags = flags; 11371da177e4SLinus Torvalds nd->depth = 0; 11381da177e4SLinus Torvalds 11391da177e4SLinus Torvalds if (*name=='/') { 1140e518ddb7SAndreas Mohr read_lock(&fs->lock); 11416ac08c39SJan Blunck if (fs->altroot.dentry && !(nd->flags & LOOKUP_NOALT)) { 11426ac08c39SJan Blunck nd->path = fs->altroot; 11436ac08c39SJan Blunck path_get(&fs->altroot); 1144e518ddb7SAndreas Mohr read_unlock(&fs->lock); 11451da177e4SLinus Torvalds if (__emul_lookup_dentry(name,nd)) 1146ea3834d9SPrasanna Meda goto out; /* found in altroot */ 1147e518ddb7SAndreas Mohr read_lock(&fs->lock); 11481da177e4SLinus Torvalds } 11496ac08c39SJan Blunck nd->path = fs->root; 11506ac08c39SJan Blunck path_get(&fs->root); 1151e518ddb7SAndreas Mohr read_unlock(&fs->lock); 11525590ff0dSUlrich Drepper } else if (dfd == AT_FDCWD) { 1153e518ddb7SAndreas Mohr read_lock(&fs->lock); 11546ac08c39SJan Blunck nd->path = fs->pwd; 11556ac08c39SJan Blunck path_get(&fs->pwd); 1156e518ddb7SAndreas Mohr read_unlock(&fs->lock); 11575590ff0dSUlrich Drepper } else { 11585590ff0dSUlrich Drepper struct dentry *dentry; 11595590ff0dSUlrich Drepper 11605590ff0dSUlrich Drepper file = fget_light(dfd, &fput_needed); 11615590ff0dSUlrich Drepper retval = -EBADF; 1162170aa3d0SUlrich Drepper if (!file) 11636d09bb62STrond Myklebust goto out_fail; 11645590ff0dSUlrich Drepper 11650f7fc9e4SJosef "Jeff" Sipek dentry = file->f_path.dentry; 11665590ff0dSUlrich Drepper 11675590ff0dSUlrich Drepper retval = -ENOTDIR; 1168170aa3d0SUlrich Drepper if (!S_ISDIR(dentry->d_inode->i_mode)) 11696d09bb62STrond Myklebust goto fput_fail; 11705590ff0dSUlrich Drepper 11715590ff0dSUlrich Drepper retval = file_permission(file, MAY_EXEC); 1172170aa3d0SUlrich Drepper if (retval) 11736d09bb62STrond Myklebust goto fput_fail; 11745590ff0dSUlrich Drepper 11755dd784d0SJan Blunck nd->path = file->f_path; 11765dd784d0SJan Blunck path_get(&file->f_path); 11775590ff0dSUlrich Drepper 11785590ff0dSUlrich Drepper fput_light(file, fput_needed); 11791da177e4SLinus Torvalds } 11802dfdd266SJosef 'Jeff' Sipek 11812dfdd266SJosef 'Jeff' Sipek retval = path_walk(name, nd); 1182ea3834d9SPrasanna Meda out: 11834ac91378SJan Blunck if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && 11844ac91378SJan Blunck nd->path.dentry->d_inode)) 11854ac91378SJan Blunck audit_inode(name, nd->path.dentry); 11866d09bb62STrond Myklebust out_fail: 1187170aa3d0SUlrich Drepper return retval; 1188170aa3d0SUlrich Drepper 11896d09bb62STrond Myklebust fput_fail: 1190170aa3d0SUlrich Drepper fput_light(file, fput_needed); 11916d09bb62STrond Myklebust goto out_fail; 11921da177e4SLinus Torvalds } 11931da177e4SLinus Torvalds 1194fc9b52cdSHarvey Harrison int path_lookup(const char *name, unsigned int flags, 11955590ff0dSUlrich Drepper struct nameidata *nd) 11965590ff0dSUlrich Drepper { 11975590ff0dSUlrich Drepper return do_path_lookup(AT_FDCWD, name, flags, nd); 11985590ff0dSUlrich Drepper } 11995590ff0dSUlrich Drepper 120016f18200SJosef 'Jeff' Sipek /** 120116f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 120216f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 120316f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 120416f18200SJosef 'Jeff' Sipek * @name: pointer to file name 120516f18200SJosef 'Jeff' Sipek * @flags: lookup flags 120616f18200SJosef 'Jeff' Sipek * @nd: pointer to nameidata 120716f18200SJosef 'Jeff' Sipek */ 120816f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 120916f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 121016f18200SJosef 'Jeff' Sipek struct nameidata *nd) 121116f18200SJosef 'Jeff' Sipek { 121216f18200SJosef 'Jeff' Sipek int retval; 121316f18200SJosef 'Jeff' Sipek 121416f18200SJosef 'Jeff' Sipek /* same as do_path_lookup */ 121516f18200SJosef 'Jeff' Sipek nd->last_type = LAST_ROOT; 121616f18200SJosef 'Jeff' Sipek nd->flags = flags; 121716f18200SJosef 'Jeff' Sipek nd->depth = 0; 121816f18200SJosef 'Jeff' Sipek 12194ac91378SJan Blunck nd->path.mnt = mntget(mnt); 12204ac91378SJan Blunck nd->path.dentry = dget(dentry); 122116f18200SJosef 'Jeff' Sipek 122216f18200SJosef 'Jeff' Sipek retval = path_walk(name, nd); 12234ac91378SJan Blunck if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && 12244ac91378SJan Blunck nd->path.dentry->d_inode)) 12254ac91378SJan Blunck audit_inode(name, nd->path.dentry); 122616f18200SJosef 'Jeff' Sipek 122716f18200SJosef 'Jeff' Sipek return retval; 122816f18200SJosef 'Jeff' Sipek 122916f18200SJosef 'Jeff' Sipek } 123016f18200SJosef 'Jeff' Sipek 12315590ff0dSUlrich Drepper static int __path_lookup_intent_open(int dfd, const char *name, 12325590ff0dSUlrich Drepper unsigned int lookup_flags, struct nameidata *nd, 12335590ff0dSUlrich Drepper int open_flags, int create_mode) 1234834f2a4aSTrond Myklebust { 1235834f2a4aSTrond Myklebust struct file *filp = get_empty_filp(); 1236834f2a4aSTrond Myklebust int err; 1237834f2a4aSTrond Myklebust 1238834f2a4aSTrond Myklebust if (filp == NULL) 1239834f2a4aSTrond Myklebust return -ENFILE; 1240834f2a4aSTrond Myklebust nd->intent.open.file = filp; 1241834f2a4aSTrond Myklebust nd->intent.open.flags = open_flags; 1242834f2a4aSTrond Myklebust nd->intent.open.create_mode = create_mode; 12435590ff0dSUlrich Drepper err = do_path_lookup(dfd, name, lookup_flags|LOOKUP_OPEN, nd); 1244834f2a4aSTrond Myklebust if (IS_ERR(nd->intent.open.file)) { 1245834f2a4aSTrond Myklebust if (err == 0) { 1246834f2a4aSTrond Myklebust err = PTR_ERR(nd->intent.open.file); 12471d957f9bSJan Blunck path_put(&nd->path); 1248834f2a4aSTrond Myklebust } 1249834f2a4aSTrond Myklebust } else if (err != 0) 1250834f2a4aSTrond Myklebust release_open_intent(nd); 1251834f2a4aSTrond Myklebust return err; 1252834f2a4aSTrond Myklebust } 1253834f2a4aSTrond Myklebust 1254834f2a4aSTrond Myklebust /** 1255834f2a4aSTrond Myklebust * path_lookup_open - lookup a file path with open intent 12567045f37bSMartin Waitz * @dfd: the directory to use as base, or AT_FDCWD 1257834f2a4aSTrond Myklebust * @name: pointer to file name 1258834f2a4aSTrond Myklebust * @lookup_flags: lookup intent flags 1259834f2a4aSTrond Myklebust * @nd: pointer to nameidata 1260834f2a4aSTrond Myklebust * @open_flags: open intent flags 1261834f2a4aSTrond Myklebust */ 12625590ff0dSUlrich Drepper int path_lookup_open(int dfd, const char *name, unsigned int lookup_flags, 1263834f2a4aSTrond Myklebust struct nameidata *nd, int open_flags) 1264834f2a4aSTrond Myklebust { 12655590ff0dSUlrich Drepper return __path_lookup_intent_open(dfd, name, lookup_flags, nd, 1266834f2a4aSTrond Myklebust open_flags, 0); 1267834f2a4aSTrond Myklebust } 1268834f2a4aSTrond Myklebust 1269834f2a4aSTrond Myklebust /** 1270834f2a4aSTrond Myklebust * path_lookup_create - lookup a file path with open + create intent 12717045f37bSMartin Waitz * @dfd: the directory to use as base, or AT_FDCWD 1272834f2a4aSTrond Myklebust * @name: pointer to file name 1273834f2a4aSTrond Myklebust * @lookup_flags: lookup intent flags 1274834f2a4aSTrond Myklebust * @nd: pointer to nameidata 1275834f2a4aSTrond Myklebust * @open_flags: open intent flags 1276834f2a4aSTrond Myklebust * @create_mode: create intent flags 1277834f2a4aSTrond Myklebust */ 12785590ff0dSUlrich Drepper static int path_lookup_create(int dfd, const char *name, 12795590ff0dSUlrich Drepper unsigned int lookup_flags, struct nameidata *nd, 12805590ff0dSUlrich Drepper int open_flags, int create_mode) 1281834f2a4aSTrond Myklebust { 12825590ff0dSUlrich Drepper return __path_lookup_intent_open(dfd, name, lookup_flags|LOOKUP_CREATE, 12835590ff0dSUlrich Drepper nd, open_flags, create_mode); 1284834f2a4aSTrond Myklebust } 1285834f2a4aSTrond Myklebust 1286834f2a4aSTrond Myklebust int __user_path_lookup_open(const char __user *name, unsigned int lookup_flags, 1287834f2a4aSTrond Myklebust struct nameidata *nd, int open_flags) 1288834f2a4aSTrond Myklebust { 1289834f2a4aSTrond Myklebust char *tmp = getname(name); 1290834f2a4aSTrond Myklebust int err = PTR_ERR(tmp); 1291834f2a4aSTrond Myklebust 1292834f2a4aSTrond Myklebust if (!IS_ERR(tmp)) { 12935590ff0dSUlrich Drepper err = __path_lookup_intent_open(AT_FDCWD, tmp, lookup_flags, nd, open_flags, 0); 1294834f2a4aSTrond Myklebust putname(tmp); 1295834f2a4aSTrond Myklebust } 1296834f2a4aSTrond Myklebust return err; 1297834f2a4aSTrond Myklebust } 1298834f2a4aSTrond Myklebust 1299eead1911SChristoph Hellwig static struct dentry *__lookup_hash(struct qstr *name, 1300eead1911SChristoph Hellwig struct dentry *base, struct nameidata *nd) 13011da177e4SLinus Torvalds { 13021da177e4SLinus Torvalds struct dentry *dentry; 13031da177e4SLinus Torvalds struct inode *inode; 13041da177e4SLinus Torvalds int err; 13051da177e4SLinus Torvalds 13061da177e4SLinus Torvalds inode = base->d_inode; 13071da177e4SLinus Torvalds 13081da177e4SLinus Torvalds /* 13091da177e4SLinus Torvalds * See if the low-level filesystem might want 13101da177e4SLinus Torvalds * to use its own hash.. 13111da177e4SLinus Torvalds */ 13121da177e4SLinus Torvalds if (base->d_op && base->d_op->d_hash) { 13131da177e4SLinus Torvalds err = base->d_op->d_hash(base, name); 13141da177e4SLinus Torvalds dentry = ERR_PTR(err); 13151da177e4SLinus Torvalds if (err < 0) 13161da177e4SLinus Torvalds goto out; 13171da177e4SLinus Torvalds } 13181da177e4SLinus Torvalds 13191da177e4SLinus Torvalds dentry = cached_lookup(base, name, nd); 13201da177e4SLinus Torvalds if (!dentry) { 13211da177e4SLinus Torvalds struct dentry *new = d_alloc(base, name); 13221da177e4SLinus Torvalds dentry = ERR_PTR(-ENOMEM); 13231da177e4SLinus Torvalds if (!new) 13241da177e4SLinus Torvalds goto out; 13251da177e4SLinus Torvalds dentry = inode->i_op->lookup(inode, new, nd); 13261da177e4SLinus Torvalds if (!dentry) 13271da177e4SLinus Torvalds dentry = new; 13281da177e4SLinus Torvalds else 13291da177e4SLinus Torvalds dput(new); 13301da177e4SLinus Torvalds } 13311da177e4SLinus Torvalds out: 13321da177e4SLinus Torvalds return dentry; 13331da177e4SLinus Torvalds } 13341da177e4SLinus Torvalds 1335057f6c01SJames Morris /* 1336057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1337057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1338057f6c01SJames Morris * SMP-safe. 1339057f6c01SJames Morris */ 1340a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 13411da177e4SLinus Torvalds { 1342eead1911SChristoph Hellwig int err; 1343eead1911SChristoph Hellwig 13444ac91378SJan Blunck err = permission(nd->path.dentry->d_inode, MAY_EXEC, nd); 1345eead1911SChristoph Hellwig if (err) 1346eead1911SChristoph Hellwig return ERR_PTR(err); 13474ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 13481da177e4SLinus Torvalds } 13491da177e4SLinus Torvalds 1350eead1911SChristoph Hellwig static int __lookup_one_len(const char *name, struct qstr *this, 1351eead1911SChristoph Hellwig struct dentry *base, int len) 13521da177e4SLinus Torvalds { 13531da177e4SLinus Torvalds unsigned long hash; 13541da177e4SLinus Torvalds unsigned int c; 13551da177e4SLinus Torvalds 1356057f6c01SJames Morris this->name = name; 1357057f6c01SJames Morris this->len = len; 13581da177e4SLinus Torvalds if (!len) 1359057f6c01SJames Morris return -EACCES; 13601da177e4SLinus Torvalds 13611da177e4SLinus Torvalds hash = init_name_hash(); 13621da177e4SLinus Torvalds while (len--) { 13631da177e4SLinus Torvalds c = *(const unsigned char *)name++; 13641da177e4SLinus Torvalds if (c == '/' || c == '\0') 1365057f6c01SJames Morris return -EACCES; 13661da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 13671da177e4SLinus Torvalds } 1368057f6c01SJames Morris this->hash = end_name_hash(hash); 1369057f6c01SJames Morris return 0; 1370057f6c01SJames Morris } 13711da177e4SLinus Torvalds 1372eead1911SChristoph Hellwig /** 1373a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1374eead1911SChristoph Hellwig * @name: pathname component to lookup 1375eead1911SChristoph Hellwig * @base: base directory to lookup from 1376eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1377eead1911SChristoph Hellwig * 1378a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1379a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1380eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1381eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1382eead1911SChristoph Hellwig */ 1383057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1384057f6c01SJames Morris { 1385057f6c01SJames Morris int err; 1386057f6c01SJames Morris struct qstr this; 1387057f6c01SJames Morris 1388057f6c01SJames Morris err = __lookup_one_len(name, &this, base, len); 1389057f6c01SJames Morris if (err) 1390057f6c01SJames Morris return ERR_PTR(err); 1391eead1911SChristoph Hellwig 1392eead1911SChristoph Hellwig err = permission(base->d_inode, MAY_EXEC, NULL); 1393eead1911SChristoph Hellwig if (err) 1394eead1911SChristoph Hellwig return ERR_PTR(err); 139549705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1396057f6c01SJames Morris } 1397057f6c01SJames Morris 1398eead1911SChristoph Hellwig /** 1399eead1911SChristoph Hellwig * lookup_one_noperm - bad hack for sysfs 1400eead1911SChristoph Hellwig * @name: pathname component to lookup 1401eead1911SChristoph Hellwig * @base: base directory to lookup from 1402eead1911SChristoph Hellwig * 1403eead1911SChristoph Hellwig * This is a variant of lookup_one_len that doesn't perform any permission 1404eead1911SChristoph Hellwig * checks. It's a horrible hack to work around the braindead sysfs 1405eead1911SChristoph Hellwig * architecture and should not be used anywhere else. 1406eead1911SChristoph Hellwig * 1407eead1911SChristoph Hellwig * DON'T USE THIS FUNCTION EVER, thanks. 1408eead1911SChristoph Hellwig */ 1409eead1911SChristoph Hellwig struct dentry *lookup_one_noperm(const char *name, struct dentry *base) 1410057f6c01SJames Morris { 1411057f6c01SJames Morris int err; 1412057f6c01SJames Morris struct qstr this; 1413057f6c01SJames Morris 1414eead1911SChristoph Hellwig err = __lookup_one_len(name, &this, base, strlen(name)); 1415057f6c01SJames Morris if (err) 1416057f6c01SJames Morris return ERR_PTR(err); 1417eead1911SChristoph Hellwig return __lookup_hash(&this, base, NULL); 14181da177e4SLinus Torvalds } 14191da177e4SLinus Torvalds 1420fc9b52cdSHarvey Harrison int __user_walk_fd(int dfd, const char __user *name, unsigned flags, 14215590ff0dSUlrich Drepper struct nameidata *nd) 14221da177e4SLinus Torvalds { 14231da177e4SLinus Torvalds char *tmp = getname(name); 14241da177e4SLinus Torvalds int err = PTR_ERR(tmp); 14251da177e4SLinus Torvalds 14261da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 14275590ff0dSUlrich Drepper err = do_path_lookup(dfd, tmp, flags, nd); 14281da177e4SLinus Torvalds putname(tmp); 14291da177e4SLinus Torvalds } 14301da177e4SLinus Torvalds return err; 14311da177e4SLinus Torvalds } 14321da177e4SLinus Torvalds 1433fc9b52cdSHarvey Harrison int __user_walk(const char __user *name, unsigned flags, struct nameidata *nd) 14345590ff0dSUlrich Drepper { 14355590ff0dSUlrich Drepper return __user_walk_fd(AT_FDCWD, name, flags, nd); 14365590ff0dSUlrich Drepper } 14375590ff0dSUlrich Drepper 14381da177e4SLinus Torvalds /* 14391da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 14401da177e4SLinus Torvalds * minimal. 14411da177e4SLinus Torvalds */ 14421da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 14431da177e4SLinus Torvalds { 14441da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 14451da177e4SLinus Torvalds return 0; 14461da177e4SLinus Torvalds if (inode->i_uid == current->fsuid) 14471da177e4SLinus Torvalds return 0; 14481da177e4SLinus Torvalds if (dir->i_uid == current->fsuid) 14491da177e4SLinus Torvalds return 0; 14501da177e4SLinus Torvalds return !capable(CAP_FOWNER); 14511da177e4SLinus Torvalds } 14521da177e4SLinus Torvalds 14531da177e4SLinus Torvalds /* 14541da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 14551da177e4SLinus Torvalds * whether the type of victim is right. 14561da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 14571da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 14581da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 14591da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 14601da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 14611da177e4SLinus Torvalds * a. be owner of dir, or 14621da177e4SLinus Torvalds * b. be owner of victim, or 14631da177e4SLinus Torvalds * c. have CAP_FOWNER capability 14641da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 14651da177e4SLinus Torvalds * links pointing to it. 14661da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 14671da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 14681da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 14691da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 14701da177e4SLinus Torvalds * nfs_async_unlink(). 14711da177e4SLinus Torvalds */ 1472858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 14731da177e4SLinus Torvalds { 14741da177e4SLinus Torvalds int error; 14751da177e4SLinus Torvalds 14761da177e4SLinus Torvalds if (!victim->d_inode) 14771da177e4SLinus Torvalds return -ENOENT; 14781da177e4SLinus Torvalds 14791da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 14805a190ae6SAl Viro audit_inode_child(victim->d_name.name, victim, dir); 14811da177e4SLinus Torvalds 14821da177e4SLinus Torvalds error = permission(dir,MAY_WRITE | MAY_EXEC, NULL); 14831da177e4SLinus Torvalds if (error) 14841da177e4SLinus Torvalds return error; 14851da177e4SLinus Torvalds if (IS_APPEND(dir)) 14861da177e4SLinus Torvalds return -EPERM; 14871da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 14881da177e4SLinus Torvalds IS_IMMUTABLE(victim->d_inode)) 14891da177e4SLinus Torvalds return -EPERM; 14901da177e4SLinus Torvalds if (isdir) { 14911da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 14921da177e4SLinus Torvalds return -ENOTDIR; 14931da177e4SLinus Torvalds if (IS_ROOT(victim)) 14941da177e4SLinus Torvalds return -EBUSY; 14951da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 14961da177e4SLinus Torvalds return -EISDIR; 14971da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 14981da177e4SLinus Torvalds return -ENOENT; 14991da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 15001da177e4SLinus Torvalds return -EBUSY; 15011da177e4SLinus Torvalds return 0; 15021da177e4SLinus Torvalds } 15031da177e4SLinus Torvalds 15041da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 15051da177e4SLinus Torvalds * dir. 15061da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 15071da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 15081da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 15091da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 15101da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 15111da177e4SLinus Torvalds */ 15121da177e4SLinus Torvalds static inline int may_create(struct inode *dir, struct dentry *child, 15131da177e4SLinus Torvalds struct nameidata *nd) 15141da177e4SLinus Torvalds { 15151da177e4SLinus Torvalds if (child->d_inode) 15161da177e4SLinus Torvalds return -EEXIST; 15171da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 15181da177e4SLinus Torvalds return -ENOENT; 15191da177e4SLinus Torvalds return permission(dir,MAY_WRITE | MAY_EXEC, nd); 15201da177e4SLinus Torvalds } 15211da177e4SLinus Torvalds 15221da177e4SLinus Torvalds /* 15231da177e4SLinus Torvalds * O_DIRECTORY translates into forcing a directory lookup. 15241da177e4SLinus Torvalds */ 15251da177e4SLinus Torvalds static inline int lookup_flags(unsigned int f) 15261da177e4SLinus Torvalds { 15271da177e4SLinus Torvalds unsigned long retval = LOOKUP_FOLLOW; 15281da177e4SLinus Torvalds 15291da177e4SLinus Torvalds if (f & O_NOFOLLOW) 15301da177e4SLinus Torvalds retval &= ~LOOKUP_FOLLOW; 15311da177e4SLinus Torvalds 15321da177e4SLinus Torvalds if (f & O_DIRECTORY) 15331da177e4SLinus Torvalds retval |= LOOKUP_DIRECTORY; 15341da177e4SLinus Torvalds 15351da177e4SLinus Torvalds return retval; 15361da177e4SLinus Torvalds } 15371da177e4SLinus Torvalds 15381da177e4SLinus Torvalds /* 15391da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 15401da177e4SLinus Torvalds */ 15411da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 15421da177e4SLinus Torvalds { 15431da177e4SLinus Torvalds struct dentry *p; 15441da177e4SLinus Torvalds 15451da177e4SLinus Torvalds if (p1 == p2) { 1546f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 15471da177e4SLinus Torvalds return NULL; 15481da177e4SLinus Torvalds } 15491da177e4SLinus Torvalds 1550a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 15511da177e4SLinus Torvalds 15521da177e4SLinus Torvalds for (p = p1; p->d_parent != p; p = p->d_parent) { 15531da177e4SLinus Torvalds if (p->d_parent == p2) { 1554f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 1555f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 15561da177e4SLinus Torvalds return p; 15571da177e4SLinus Torvalds } 15581da177e4SLinus Torvalds } 15591da177e4SLinus Torvalds 15601da177e4SLinus Torvalds for (p = p2; p->d_parent != p; p = p->d_parent) { 15611da177e4SLinus Torvalds if (p->d_parent == p1) { 1562f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1563f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 15641da177e4SLinus Torvalds return p; 15651da177e4SLinus Torvalds } 15661da177e4SLinus Torvalds } 15671da177e4SLinus Torvalds 1568f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1569f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 15701da177e4SLinus Torvalds return NULL; 15711da177e4SLinus Torvalds } 15721da177e4SLinus Torvalds 15731da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 15741da177e4SLinus Torvalds { 15751b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 15761da177e4SLinus Torvalds if (p1 != p2) { 15771b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 1578a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 15791da177e4SLinus Torvalds } 15801da177e4SLinus Torvalds } 15811da177e4SLinus Torvalds 15821da177e4SLinus Torvalds int vfs_create(struct inode *dir, struct dentry *dentry, int mode, 15831da177e4SLinus Torvalds struct nameidata *nd) 15841da177e4SLinus Torvalds { 15851da177e4SLinus Torvalds int error = may_create(dir, dentry, nd); 15861da177e4SLinus Torvalds 15871da177e4SLinus Torvalds if (error) 15881da177e4SLinus Torvalds return error; 15891da177e4SLinus Torvalds 15901da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->create) 15911da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 15921da177e4SLinus Torvalds mode &= S_IALLUGO; 15931da177e4SLinus Torvalds mode |= S_IFREG; 15941da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 15951da177e4SLinus Torvalds if (error) 15961da177e4SLinus Torvalds return error; 15971da177e4SLinus Torvalds DQUOT_INIT(dir); 15981da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 1599a74574aaSStephen Smalley if (!error) 1600f38aa942SAmy Griffis fsnotify_create(dir, dentry); 16011da177e4SLinus Torvalds return error; 16021da177e4SLinus Torvalds } 16031da177e4SLinus Torvalds 16041da177e4SLinus Torvalds int may_open(struct nameidata *nd, int acc_mode, int flag) 16051da177e4SLinus Torvalds { 16064ac91378SJan Blunck struct dentry *dentry = nd->path.dentry; 16071da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 16081da177e4SLinus Torvalds int error; 16091da177e4SLinus Torvalds 16101da177e4SLinus Torvalds if (!inode) 16111da177e4SLinus Torvalds return -ENOENT; 16121da177e4SLinus Torvalds 16131da177e4SLinus Torvalds if (S_ISLNK(inode->i_mode)) 16141da177e4SLinus Torvalds return -ELOOP; 16151da177e4SLinus Torvalds 1616974a9f0bSLinus Torvalds if (S_ISDIR(inode->i_mode) && (acc_mode & MAY_WRITE)) 16171da177e4SLinus Torvalds return -EISDIR; 16181da177e4SLinus Torvalds 16191da177e4SLinus Torvalds /* 16201da177e4SLinus Torvalds * FIFO's, sockets and device files are special: they don't 16211da177e4SLinus Torvalds * actually live on the filesystem itself, and as such you 16221da177e4SLinus Torvalds * can write to them even if the filesystem is read-only. 16231da177e4SLinus Torvalds */ 16241da177e4SLinus Torvalds if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) { 16251da177e4SLinus Torvalds flag &= ~O_TRUNC; 16261da177e4SLinus Torvalds } else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) { 16274ac91378SJan Blunck if (nd->path.mnt->mnt_flags & MNT_NODEV) 16281da177e4SLinus Torvalds return -EACCES; 16291da177e4SLinus Torvalds 16301da177e4SLinus Torvalds flag &= ~O_TRUNC; 16314a3fd211SDave Hansen } 1632b41572e9SDave Hansen 1633b41572e9SDave Hansen error = vfs_permission(nd, acc_mode); 1634b41572e9SDave Hansen if (error) 1635b41572e9SDave Hansen return error; 16361da177e4SLinus Torvalds /* 16371da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 16381da177e4SLinus Torvalds */ 16391da177e4SLinus Torvalds if (IS_APPEND(inode)) { 16401da177e4SLinus Torvalds if ((flag & FMODE_WRITE) && !(flag & O_APPEND)) 16411da177e4SLinus Torvalds return -EPERM; 16421da177e4SLinus Torvalds if (flag & O_TRUNC) 16431da177e4SLinus Torvalds return -EPERM; 16441da177e4SLinus Torvalds } 16451da177e4SLinus Torvalds 16461da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 16471da177e4SLinus Torvalds if (flag & O_NOATIME) 16483bd858abSSatyam Sharma if (!is_owner_or_cap(inode)) 16491da177e4SLinus Torvalds return -EPERM; 16501da177e4SLinus Torvalds 16511da177e4SLinus Torvalds /* 16521da177e4SLinus Torvalds * Ensure there are no outstanding leases on the file. 16531da177e4SLinus Torvalds */ 16541da177e4SLinus Torvalds error = break_lease(inode, flag); 16551da177e4SLinus Torvalds if (error) 16561da177e4SLinus Torvalds return error; 16571da177e4SLinus Torvalds 16581da177e4SLinus Torvalds if (flag & O_TRUNC) { 16591da177e4SLinus Torvalds error = get_write_access(inode); 16601da177e4SLinus Torvalds if (error) 16611da177e4SLinus Torvalds return error; 16621da177e4SLinus Torvalds 16631da177e4SLinus Torvalds /* 16641da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 16651da177e4SLinus Torvalds */ 16661da177e4SLinus Torvalds error = locks_verify_locked(inode); 16671da177e4SLinus Torvalds if (!error) { 16681da177e4SLinus Torvalds DQUOT_INIT(inode); 16691da177e4SLinus Torvalds 1670d139d7ffSMiklos Szeredi error = do_truncate(dentry, 0, 1671d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 1672d139d7ffSMiklos Szeredi NULL); 16731da177e4SLinus Torvalds } 16741da177e4SLinus Torvalds put_write_access(inode); 16751da177e4SLinus Torvalds if (error) 16761da177e4SLinus Torvalds return error; 16771da177e4SLinus Torvalds } else 16781da177e4SLinus Torvalds if (flag & FMODE_WRITE) 16791da177e4SLinus Torvalds DQUOT_INIT(inode); 16801da177e4SLinus Torvalds 16811da177e4SLinus Torvalds return 0; 16821da177e4SLinus Torvalds } 16831da177e4SLinus Torvalds 1684d57999e1SDave Hansen /* 1685d57999e1SDave Hansen * Be careful about ever adding any more callers of this 1686d57999e1SDave Hansen * function. Its flags must be in the namei format, not 1687d57999e1SDave Hansen * what get passed to sys_open(). 1688d57999e1SDave Hansen */ 1689d57999e1SDave Hansen static int __open_namei_create(struct nameidata *nd, struct path *path, 1690aab520e2SDave Hansen int flag, int mode) 1691aab520e2SDave Hansen { 1692aab520e2SDave Hansen int error; 16934ac91378SJan Blunck struct dentry *dir = nd->path.dentry; 1694aab520e2SDave Hansen 1695aab520e2SDave Hansen if (!IS_POSIXACL(dir->d_inode)) 1696aab520e2SDave Hansen mode &= ~current->fs->umask; 1697aab520e2SDave Hansen error = vfs_create(dir->d_inode, path->dentry, mode, nd); 1698aab520e2SDave Hansen mutex_unlock(&dir->d_inode->i_mutex); 16994ac91378SJan Blunck dput(nd->path.dentry); 17004ac91378SJan Blunck nd->path.dentry = path->dentry; 1701aab520e2SDave Hansen if (error) 1702aab520e2SDave Hansen return error; 1703aab520e2SDave Hansen /* Don't check for write permission, don't truncate */ 1704aab520e2SDave Hansen return may_open(nd, 0, flag & ~O_TRUNC); 1705aab520e2SDave Hansen } 1706aab520e2SDave Hansen 17071da177e4SLinus Torvalds /* 1708d57999e1SDave Hansen * Note that while the flag value (low two bits) for sys_open means: 1709d57999e1SDave Hansen * 00 - read-only 1710d57999e1SDave Hansen * 01 - write-only 1711d57999e1SDave Hansen * 10 - read-write 1712d57999e1SDave Hansen * 11 - special 1713d57999e1SDave Hansen * it is changed into 1714d57999e1SDave Hansen * 00 - no permissions needed 1715d57999e1SDave Hansen * 01 - read-permission 1716d57999e1SDave Hansen * 10 - write-permission 1717d57999e1SDave Hansen * 11 - read-write 1718d57999e1SDave Hansen * for the internal routines (ie open_namei()/follow_link() etc) 1719d57999e1SDave Hansen * This is more logical, and also allows the 00 "no perm needed" 1720d57999e1SDave Hansen * to be used for symlinks (where the permissions are checked 1721d57999e1SDave Hansen * later). 1722d57999e1SDave Hansen * 1723d57999e1SDave Hansen */ 1724d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 1725d57999e1SDave Hansen { 1726d57999e1SDave Hansen if ((flag+1) & O_ACCMODE) 1727d57999e1SDave Hansen flag++; 1728d57999e1SDave Hansen return flag; 1729d57999e1SDave Hansen } 1730d57999e1SDave Hansen 17314a3fd211SDave Hansen static int open_will_write_to_fs(int flag, struct inode *inode) 17324a3fd211SDave Hansen { 1733d57999e1SDave Hansen /* 17344a3fd211SDave Hansen * We'll never write to the fs underlying 17354a3fd211SDave Hansen * a device file. 17364a3fd211SDave Hansen */ 17374a3fd211SDave Hansen if (special_file(inode->i_mode)) 17384a3fd211SDave Hansen return 0; 17394a3fd211SDave Hansen return (flag & O_TRUNC); 17404a3fd211SDave Hansen } 17414a3fd211SDave Hansen 17424a3fd211SDave Hansen /* 17434a3fd211SDave Hansen * Note that the low bits of the passed in "open_flag" 17444a3fd211SDave Hansen * are not the same as in the local variable "flag". See 17454a3fd211SDave Hansen * open_to_namei_flags() for more details. 17461da177e4SLinus Torvalds */ 1747a70e65dfSChristoph Hellwig struct file *do_filp_open(int dfd, const char *pathname, 1748a70e65dfSChristoph Hellwig int open_flag, int mode) 17491da177e4SLinus Torvalds { 17504a3fd211SDave Hansen struct file *filp; 1751a70e65dfSChristoph Hellwig struct nameidata nd; 1752834f2a4aSTrond Myklebust int acc_mode, error; 17534e7506e4SAl Viro struct path path; 17541da177e4SLinus Torvalds struct dentry *dir; 17551da177e4SLinus Torvalds int count = 0; 17564a3fd211SDave Hansen int will_write; 1757d57999e1SDave Hansen int flag = open_to_namei_flags(open_flag); 17581da177e4SLinus Torvalds 17591da177e4SLinus Torvalds acc_mode = ACC_MODE(flag); 17601da177e4SLinus Torvalds 1761834f2a4aSTrond Myklebust /* O_TRUNC implies we need access checks for write permissions */ 1762834f2a4aSTrond Myklebust if (flag & O_TRUNC) 1763834f2a4aSTrond Myklebust acc_mode |= MAY_WRITE; 1764834f2a4aSTrond Myklebust 17651da177e4SLinus Torvalds /* Allow the LSM permission hook to distinguish append 17661da177e4SLinus Torvalds access from general write access. */ 17671da177e4SLinus Torvalds if (flag & O_APPEND) 17681da177e4SLinus Torvalds acc_mode |= MAY_APPEND; 17691da177e4SLinus Torvalds 17701da177e4SLinus Torvalds /* 17711da177e4SLinus Torvalds * The simplest case - just a plain lookup. 17721da177e4SLinus Torvalds */ 17731da177e4SLinus Torvalds if (!(flag & O_CREAT)) { 17745590ff0dSUlrich Drepper error = path_lookup_open(dfd, pathname, lookup_flags(flag), 1775a70e65dfSChristoph Hellwig &nd, flag); 17761da177e4SLinus Torvalds if (error) 1777a70e65dfSChristoph Hellwig return ERR_PTR(error); 17781da177e4SLinus Torvalds goto ok; 17791da177e4SLinus Torvalds } 17801da177e4SLinus Torvalds 17811da177e4SLinus Torvalds /* 17821da177e4SLinus Torvalds * Create - we need to know the parent. 17831da177e4SLinus Torvalds */ 1784a70e65dfSChristoph Hellwig error = path_lookup_create(dfd, pathname, LOOKUP_PARENT, 1785a70e65dfSChristoph Hellwig &nd, flag, mode); 17861da177e4SLinus Torvalds if (error) 1787a70e65dfSChristoph Hellwig return ERR_PTR(error); 17881da177e4SLinus Torvalds 17891da177e4SLinus Torvalds /* 17901da177e4SLinus Torvalds * We have the parent and last component. First of all, check 17911da177e4SLinus Torvalds * that we are not asked to creat(2) an obvious directory - that 17921da177e4SLinus Torvalds * will not do. 17931da177e4SLinus Torvalds */ 17941da177e4SLinus Torvalds error = -EISDIR; 1795a70e65dfSChristoph Hellwig if (nd.last_type != LAST_NORM || nd.last.name[nd.last.len]) 17961da177e4SLinus Torvalds goto exit; 17971da177e4SLinus Torvalds 1798a70e65dfSChristoph Hellwig dir = nd.path.dentry; 1799a70e65dfSChristoph Hellwig nd.flags &= ~LOOKUP_PARENT; 18001b1dcc1bSJes Sorensen mutex_lock(&dir->d_inode->i_mutex); 1801a70e65dfSChristoph Hellwig path.dentry = lookup_hash(&nd); 1802a70e65dfSChristoph Hellwig path.mnt = nd.path.mnt; 18031da177e4SLinus Torvalds 18041da177e4SLinus Torvalds do_last: 18054e7506e4SAl Viro error = PTR_ERR(path.dentry); 18064e7506e4SAl Viro if (IS_ERR(path.dentry)) { 18071b1dcc1bSJes Sorensen mutex_unlock(&dir->d_inode->i_mutex); 18081da177e4SLinus Torvalds goto exit; 18091da177e4SLinus Torvalds } 18101da177e4SLinus Torvalds 1811a70e65dfSChristoph Hellwig if (IS_ERR(nd.intent.open.file)) { 1812a70e65dfSChristoph Hellwig error = PTR_ERR(nd.intent.open.file); 18134a3fd211SDave Hansen goto exit_mutex_unlock; 18144af4c52fSOleg Drokin } 18154af4c52fSOleg Drokin 18161da177e4SLinus Torvalds /* Negative dentry, just create the file */ 18174e7506e4SAl Viro if (!path.dentry->d_inode) { 18184a3fd211SDave Hansen /* 18194a3fd211SDave Hansen * This write is needed to ensure that a 18204a3fd211SDave Hansen * ro->rw transition does not occur between 18214a3fd211SDave Hansen * the time when the file is created and when 18224a3fd211SDave Hansen * a permanent write count is taken through 18234a3fd211SDave Hansen * the 'struct file' in nameidata_to_filp(). 18244a3fd211SDave Hansen */ 18254a3fd211SDave Hansen error = mnt_want_write(nd.path.mnt); 18261da177e4SLinus Torvalds if (error) 18274a3fd211SDave Hansen goto exit_mutex_unlock; 18284a3fd211SDave Hansen error = __open_namei_create(&nd, &path, flag, mode); 18294a3fd211SDave Hansen if (error) { 18304a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 18311da177e4SLinus Torvalds goto exit; 18324a3fd211SDave Hansen } 18334a3fd211SDave Hansen filp = nameidata_to_filp(&nd, open_flag); 18344a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 18354a3fd211SDave Hansen return filp; 18361da177e4SLinus Torvalds } 18371da177e4SLinus Torvalds 18381da177e4SLinus Torvalds /* 18391da177e4SLinus Torvalds * It already exists. 18401da177e4SLinus Torvalds */ 18411b1dcc1bSJes Sorensen mutex_unlock(&dir->d_inode->i_mutex); 18425a190ae6SAl Viro audit_inode(pathname, path.dentry); 18431da177e4SLinus Torvalds 18441da177e4SLinus Torvalds error = -EEXIST; 18451da177e4SLinus Torvalds if (flag & O_EXCL) 18461da177e4SLinus Torvalds goto exit_dput; 18471da177e4SLinus Torvalds 1848e13b210fSAl Viro if (__follow_mount(&path)) { 18491da177e4SLinus Torvalds error = -ELOOP; 1850ba7a4c1aSAl Viro if (flag & O_NOFOLLOW) 1851ba7a4c1aSAl Viro goto exit_dput; 18521da177e4SLinus Torvalds } 18533e2efce0SAmy Griffis 18541da177e4SLinus Torvalds error = -ENOENT; 18554e7506e4SAl Viro if (!path.dentry->d_inode) 18561da177e4SLinus Torvalds goto exit_dput; 18574e7506e4SAl Viro if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link) 18581da177e4SLinus Torvalds goto do_link; 18591da177e4SLinus Torvalds 1860a70e65dfSChristoph Hellwig path_to_nameidata(&path, &nd); 18611da177e4SLinus Torvalds error = -EISDIR; 18624e7506e4SAl Viro if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode)) 18631da177e4SLinus Torvalds goto exit; 18641da177e4SLinus Torvalds ok: 18654a3fd211SDave Hansen /* 18664a3fd211SDave Hansen * Consider: 18674a3fd211SDave Hansen * 1. may_open() truncates a file 18684a3fd211SDave Hansen * 2. a rw->ro mount transition occurs 18694a3fd211SDave Hansen * 3. nameidata_to_filp() fails due to 18704a3fd211SDave Hansen * the ro mount. 18714a3fd211SDave Hansen * That would be inconsistent, and should 18724a3fd211SDave Hansen * be avoided. Taking this mnt write here 18734a3fd211SDave Hansen * ensures that (2) can not occur. 18744a3fd211SDave Hansen */ 18754a3fd211SDave Hansen will_write = open_will_write_to_fs(flag, nd.path.dentry->d_inode); 18764a3fd211SDave Hansen if (will_write) { 18774a3fd211SDave Hansen error = mnt_want_write(nd.path.mnt); 18781da177e4SLinus Torvalds if (error) 18791da177e4SLinus Torvalds goto exit; 18804a3fd211SDave Hansen } 18814a3fd211SDave Hansen error = may_open(&nd, acc_mode, flag); 18824a3fd211SDave Hansen if (error) { 18834a3fd211SDave Hansen if (will_write) 18844a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 18854a3fd211SDave Hansen goto exit; 18864a3fd211SDave Hansen } 18874a3fd211SDave Hansen filp = nameidata_to_filp(&nd, open_flag); 18884a3fd211SDave Hansen /* 18894a3fd211SDave Hansen * It is now safe to drop the mnt write 18904a3fd211SDave Hansen * because the filp has had a write taken 18914a3fd211SDave Hansen * on its behalf. 18924a3fd211SDave Hansen */ 18934a3fd211SDave Hansen if (will_write) 18944a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 18954a3fd211SDave Hansen return filp; 18961da177e4SLinus Torvalds 18974a3fd211SDave Hansen exit_mutex_unlock: 18984a3fd211SDave Hansen mutex_unlock(&dir->d_inode->i_mutex); 18991da177e4SLinus Torvalds exit_dput: 1900a70e65dfSChristoph Hellwig path_put_conditional(&path, &nd); 19011da177e4SLinus Torvalds exit: 1902a70e65dfSChristoph Hellwig if (!IS_ERR(nd.intent.open.file)) 1903a70e65dfSChristoph Hellwig release_open_intent(&nd); 1904a70e65dfSChristoph Hellwig path_put(&nd.path); 1905a70e65dfSChristoph Hellwig return ERR_PTR(error); 19061da177e4SLinus Torvalds 19071da177e4SLinus Torvalds do_link: 19081da177e4SLinus Torvalds error = -ELOOP; 19091da177e4SLinus Torvalds if (flag & O_NOFOLLOW) 19101da177e4SLinus Torvalds goto exit_dput; 19111da177e4SLinus Torvalds /* 19121da177e4SLinus Torvalds * This is subtle. Instead of calling do_follow_link() we do the 19131da177e4SLinus Torvalds * thing by hands. The reason is that this way we have zero link_count 19141da177e4SLinus Torvalds * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT. 19151da177e4SLinus Torvalds * After that we have the parent and last component, i.e. 19161da177e4SLinus Torvalds * we are in the same situation as after the first path_walk(). 19171da177e4SLinus Torvalds * Well, almost - if the last component is normal we get its copy 19181da177e4SLinus Torvalds * stored in nd->last.name and we will have to putname() it when we 19191da177e4SLinus Torvalds * are done. Procfs-like symlinks just set LAST_BIND. 19201da177e4SLinus Torvalds */ 1921a70e65dfSChristoph Hellwig nd.flags |= LOOKUP_PARENT; 1922a70e65dfSChristoph Hellwig error = security_inode_follow_link(path.dentry, &nd); 19231da177e4SLinus Torvalds if (error) 19241da177e4SLinus Torvalds goto exit_dput; 1925a70e65dfSChristoph Hellwig error = __do_follow_link(&path, &nd); 1926de459215SKirill Korotaev if (error) { 1927de459215SKirill Korotaev /* Does someone understand code flow here? Or it is only 1928de459215SKirill Korotaev * me so stupid? Anathema to whoever designed this non-sense 1929de459215SKirill Korotaev * with "intent.open". 1930de459215SKirill Korotaev */ 1931a70e65dfSChristoph Hellwig release_open_intent(&nd); 1932a70e65dfSChristoph Hellwig return ERR_PTR(error); 1933de459215SKirill Korotaev } 1934a70e65dfSChristoph Hellwig nd.flags &= ~LOOKUP_PARENT; 1935a70e65dfSChristoph Hellwig if (nd.last_type == LAST_BIND) 19361da177e4SLinus Torvalds goto ok; 19371da177e4SLinus Torvalds error = -EISDIR; 1938a70e65dfSChristoph Hellwig if (nd.last_type != LAST_NORM) 19391da177e4SLinus Torvalds goto exit; 1940a70e65dfSChristoph Hellwig if (nd.last.name[nd.last.len]) { 1941a70e65dfSChristoph Hellwig __putname(nd.last.name); 19421da177e4SLinus Torvalds goto exit; 19431da177e4SLinus Torvalds } 19441da177e4SLinus Torvalds error = -ELOOP; 19451da177e4SLinus Torvalds if (count++==32) { 1946a70e65dfSChristoph Hellwig __putname(nd.last.name); 19471da177e4SLinus Torvalds goto exit; 19481da177e4SLinus Torvalds } 1949a70e65dfSChristoph Hellwig dir = nd.path.dentry; 19501b1dcc1bSJes Sorensen mutex_lock(&dir->d_inode->i_mutex); 1951a70e65dfSChristoph Hellwig path.dentry = lookup_hash(&nd); 1952a70e65dfSChristoph Hellwig path.mnt = nd.path.mnt; 1953a70e65dfSChristoph Hellwig __putname(nd.last.name); 19541da177e4SLinus Torvalds goto do_last; 19551da177e4SLinus Torvalds } 19561da177e4SLinus Torvalds 19571da177e4SLinus Torvalds /** 1958a70e65dfSChristoph Hellwig * filp_open - open file and return file pointer 1959a70e65dfSChristoph Hellwig * 1960a70e65dfSChristoph Hellwig * @filename: path to open 1961a70e65dfSChristoph Hellwig * @flags: open flags as per the open(2) second argument 1962a70e65dfSChristoph Hellwig * @mode: mode for the new file if O_CREAT is set, else ignored 1963a70e65dfSChristoph Hellwig * 1964a70e65dfSChristoph Hellwig * This is the helper to open a file from kernelspace if you really 1965a70e65dfSChristoph Hellwig * have to. But in generally you should not do this, so please move 1966a70e65dfSChristoph Hellwig * along, nothing to see here.. 1967a70e65dfSChristoph Hellwig */ 1968a70e65dfSChristoph Hellwig struct file *filp_open(const char *filename, int flags, int mode) 1969a70e65dfSChristoph Hellwig { 1970a70e65dfSChristoph Hellwig return do_filp_open(AT_FDCWD, filename, flags, mode); 1971a70e65dfSChristoph Hellwig } 1972a70e65dfSChristoph Hellwig EXPORT_SYMBOL(filp_open); 1973a70e65dfSChristoph Hellwig 1974a70e65dfSChristoph Hellwig /** 19751da177e4SLinus Torvalds * lookup_create - lookup a dentry, creating it if it doesn't exist 19761da177e4SLinus Torvalds * @nd: nameidata info 19771da177e4SLinus Torvalds * @is_dir: directory flag 19781da177e4SLinus Torvalds * 19791da177e4SLinus Torvalds * Simple function to lookup and return a dentry and create it 19801da177e4SLinus Torvalds * if it doesn't exist. Is SMP-safe. 1981c663e5d8SChristoph Hellwig * 19824ac91378SJan Blunck * Returns with nd->path.dentry->d_inode->i_mutex locked. 19831da177e4SLinus Torvalds */ 19841da177e4SLinus Torvalds struct dentry *lookup_create(struct nameidata *nd, int is_dir) 19851da177e4SLinus Torvalds { 1986c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 19871da177e4SLinus Torvalds 19884ac91378SJan Blunck mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 1989c663e5d8SChristoph Hellwig /* 1990c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 1991c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 1992c663e5d8SChristoph Hellwig */ 19931da177e4SLinus Torvalds if (nd->last_type != LAST_NORM) 19941da177e4SLinus Torvalds goto fail; 19951da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 1996a634904aSASANO Masahiro nd->flags |= LOOKUP_CREATE; 1997a634904aSASANO Masahiro nd->intent.open.flags = O_EXCL; 1998c663e5d8SChristoph Hellwig 1999c663e5d8SChristoph Hellwig /* 2000c663e5d8SChristoph Hellwig * Do the final lookup. 2001c663e5d8SChristoph Hellwig */ 200249705b77SChristoph Hellwig dentry = lookup_hash(nd); 20031da177e4SLinus Torvalds if (IS_ERR(dentry)) 20041da177e4SLinus Torvalds goto fail; 2005c663e5d8SChristoph Hellwig 2006e9baf6e5SAl Viro if (dentry->d_inode) 2007e9baf6e5SAl Viro goto eexist; 2008c663e5d8SChristoph Hellwig /* 2009c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 2010c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 2011c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 2012c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 2013c663e5d8SChristoph Hellwig */ 2014e9baf6e5SAl Viro if (unlikely(!is_dir && nd->last.name[nd->last.len])) { 20151da177e4SLinus Torvalds dput(dentry); 20161da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 2017e9baf6e5SAl Viro } 2018e9baf6e5SAl Viro return dentry; 2019e9baf6e5SAl Viro eexist: 2020e9baf6e5SAl Viro dput(dentry); 2021e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 20221da177e4SLinus Torvalds fail: 20231da177e4SLinus Torvalds return dentry; 20241da177e4SLinus Torvalds } 2025f81a0bffSChristoph Hellwig EXPORT_SYMBOL_GPL(lookup_create); 20261da177e4SLinus Torvalds 20271da177e4SLinus Torvalds int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 20281da177e4SLinus Torvalds { 20291da177e4SLinus Torvalds int error = may_create(dir, dentry, NULL); 20301da177e4SLinus Torvalds 20311da177e4SLinus Torvalds if (error) 20321da177e4SLinus Torvalds return error; 20331da177e4SLinus Torvalds 20341da177e4SLinus Torvalds if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 20351da177e4SLinus Torvalds return -EPERM; 20361da177e4SLinus Torvalds 20371da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->mknod) 20381da177e4SLinus Torvalds return -EPERM; 20391da177e4SLinus Torvalds 204008ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 204108ce5f16SSerge E. Hallyn if (error) 204208ce5f16SSerge E. Hallyn return error; 204308ce5f16SSerge E. Hallyn 20441da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 20451da177e4SLinus Torvalds if (error) 20461da177e4SLinus Torvalds return error; 20471da177e4SLinus Torvalds 20481da177e4SLinus Torvalds DQUOT_INIT(dir); 20491da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 2050a74574aaSStephen Smalley if (!error) 2051f38aa942SAmy Griffis fsnotify_create(dir, dentry); 20521da177e4SLinus Torvalds return error; 20531da177e4SLinus Torvalds } 20541da177e4SLinus Torvalds 2055463c3197SDave Hansen static int may_mknod(mode_t mode) 2056463c3197SDave Hansen { 2057463c3197SDave Hansen switch (mode & S_IFMT) { 2058463c3197SDave Hansen case S_IFREG: 2059463c3197SDave Hansen case S_IFCHR: 2060463c3197SDave Hansen case S_IFBLK: 2061463c3197SDave Hansen case S_IFIFO: 2062463c3197SDave Hansen case S_IFSOCK: 2063463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 2064463c3197SDave Hansen return 0; 2065463c3197SDave Hansen case S_IFDIR: 2066463c3197SDave Hansen return -EPERM; 2067463c3197SDave Hansen default: 2068463c3197SDave Hansen return -EINVAL; 2069463c3197SDave Hansen } 2070463c3197SDave Hansen } 2071463c3197SDave Hansen 20725590ff0dSUlrich Drepper asmlinkage long sys_mknodat(int dfd, const char __user *filename, int mode, 20735590ff0dSUlrich Drepper unsigned dev) 20741da177e4SLinus Torvalds { 20751da177e4SLinus Torvalds int error = 0; 20761da177e4SLinus Torvalds char * tmp; 20771da177e4SLinus Torvalds struct dentry * dentry; 20781da177e4SLinus Torvalds struct nameidata nd; 20791da177e4SLinus Torvalds 20801da177e4SLinus Torvalds if (S_ISDIR(mode)) 20811da177e4SLinus Torvalds return -EPERM; 20821da177e4SLinus Torvalds tmp = getname(filename); 20831da177e4SLinus Torvalds if (IS_ERR(tmp)) 20841da177e4SLinus Torvalds return PTR_ERR(tmp); 20851da177e4SLinus Torvalds 20865590ff0dSUlrich Drepper error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd); 20871da177e4SLinus Torvalds if (error) 20881da177e4SLinus Torvalds goto out; 20891da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 2090463c3197SDave Hansen if (IS_ERR(dentry)) { 20911da177e4SLinus Torvalds error = PTR_ERR(dentry); 2092463c3197SDave Hansen goto out_unlock; 2093463c3197SDave Hansen } 20944ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 20951da177e4SLinus Torvalds mode &= ~current->fs->umask; 2096463c3197SDave Hansen error = may_mknod(mode); 2097463c3197SDave Hansen if (error) 2098463c3197SDave Hansen goto out_dput; 2099463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2100463c3197SDave Hansen if (error) 2101463c3197SDave Hansen goto out_dput; 21021da177e4SLinus Torvalds switch (mode & S_IFMT) { 21031da177e4SLinus Torvalds case 0: case S_IFREG: 21044ac91378SJan Blunck error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); 21051da177e4SLinus Torvalds break; 21061da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 21074ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, 21081da177e4SLinus Torvalds new_decode_dev(dev)); 21091da177e4SLinus Torvalds break; 21101da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 21114ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); 21121da177e4SLinus Torvalds break; 21131da177e4SLinus Torvalds } 2114463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2115463c3197SDave Hansen out_dput: 21161da177e4SLinus Torvalds dput(dentry); 2117463c3197SDave Hansen out_unlock: 21184ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 21191d957f9bSJan Blunck path_put(&nd.path); 21201da177e4SLinus Torvalds out: 21211da177e4SLinus Torvalds putname(tmp); 21221da177e4SLinus Torvalds 21231da177e4SLinus Torvalds return error; 21241da177e4SLinus Torvalds } 21251da177e4SLinus Torvalds 21265590ff0dSUlrich Drepper asmlinkage long sys_mknod(const char __user *filename, int mode, unsigned dev) 21275590ff0dSUlrich Drepper { 21285590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 21295590ff0dSUlrich Drepper } 21305590ff0dSUlrich Drepper 21311da177e4SLinus Torvalds int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 21321da177e4SLinus Torvalds { 21331da177e4SLinus Torvalds int error = may_create(dir, dentry, NULL); 21341da177e4SLinus Torvalds 21351da177e4SLinus Torvalds if (error) 21361da177e4SLinus Torvalds return error; 21371da177e4SLinus Torvalds 21381da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->mkdir) 21391da177e4SLinus Torvalds return -EPERM; 21401da177e4SLinus Torvalds 21411da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 21421da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 21431da177e4SLinus Torvalds if (error) 21441da177e4SLinus Torvalds return error; 21451da177e4SLinus Torvalds 21461da177e4SLinus Torvalds DQUOT_INIT(dir); 21471da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2148a74574aaSStephen Smalley if (!error) 2149f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 21501da177e4SLinus Torvalds return error; 21511da177e4SLinus Torvalds } 21521da177e4SLinus Torvalds 21535590ff0dSUlrich Drepper asmlinkage long sys_mkdirat(int dfd, const char __user *pathname, int mode) 21541da177e4SLinus Torvalds { 21551da177e4SLinus Torvalds int error = 0; 21561da177e4SLinus Torvalds char * tmp; 21576902d925SDave Hansen struct dentry *dentry; 21586902d925SDave Hansen struct nameidata nd; 21591da177e4SLinus Torvalds 21601da177e4SLinus Torvalds tmp = getname(pathname); 21611da177e4SLinus Torvalds error = PTR_ERR(tmp); 21626902d925SDave Hansen if (IS_ERR(tmp)) 21636902d925SDave Hansen goto out_err; 21641da177e4SLinus Torvalds 21655590ff0dSUlrich Drepper error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd); 21661da177e4SLinus Torvalds if (error) 21671da177e4SLinus Torvalds goto out; 21681da177e4SLinus Torvalds dentry = lookup_create(&nd, 1); 21691da177e4SLinus Torvalds error = PTR_ERR(dentry); 21706902d925SDave Hansen if (IS_ERR(dentry)) 21716902d925SDave Hansen goto out_unlock; 21726902d925SDave Hansen 21734ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 21741da177e4SLinus Torvalds mode &= ~current->fs->umask; 2175463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2176463c3197SDave Hansen if (error) 2177463c3197SDave Hansen goto out_dput; 21784ac91378SJan Blunck error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); 2179463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2180463c3197SDave Hansen out_dput: 21811da177e4SLinus Torvalds dput(dentry); 21826902d925SDave Hansen out_unlock: 21834ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 21841d957f9bSJan Blunck path_put(&nd.path); 21851da177e4SLinus Torvalds out: 21861da177e4SLinus Torvalds putname(tmp); 21876902d925SDave Hansen out_err: 21881da177e4SLinus Torvalds return error; 21891da177e4SLinus Torvalds } 21901da177e4SLinus Torvalds 21915590ff0dSUlrich Drepper asmlinkage long sys_mkdir(const char __user *pathname, int mode) 21925590ff0dSUlrich Drepper { 21935590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 21945590ff0dSUlrich Drepper } 21955590ff0dSUlrich Drepper 21961da177e4SLinus Torvalds /* 21971da177e4SLinus Torvalds * We try to drop the dentry early: we should have 21981da177e4SLinus Torvalds * a usage count of 2 if we're the only user of this 21991da177e4SLinus Torvalds * dentry, and if that is true (possibly after pruning 22001da177e4SLinus Torvalds * the dcache), then we drop the dentry now. 22011da177e4SLinus Torvalds * 22021da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 22031da177e4SLinus Torvalds * do a 22041da177e4SLinus Torvalds * 22051da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 22061da177e4SLinus Torvalds * return -EBUSY; 22071da177e4SLinus Torvalds * 22081da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 22091da177e4SLinus Torvalds * that is still in use by something else.. 22101da177e4SLinus Torvalds */ 22111da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 22121da177e4SLinus Torvalds { 22131da177e4SLinus Torvalds dget(dentry); 22141da177e4SLinus Torvalds shrink_dcache_parent(dentry); 22151da177e4SLinus Torvalds spin_lock(&dcache_lock); 22161da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 22171da177e4SLinus Torvalds if (atomic_read(&dentry->d_count) == 2) 22181da177e4SLinus Torvalds __d_drop(dentry); 22191da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 22201da177e4SLinus Torvalds spin_unlock(&dcache_lock); 22211da177e4SLinus Torvalds } 22221da177e4SLinus Torvalds 22231da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 22241da177e4SLinus Torvalds { 22251da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 22261da177e4SLinus Torvalds 22271da177e4SLinus Torvalds if (error) 22281da177e4SLinus Torvalds return error; 22291da177e4SLinus Torvalds 22301da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->rmdir) 22311da177e4SLinus Torvalds return -EPERM; 22321da177e4SLinus Torvalds 22331da177e4SLinus Torvalds DQUOT_INIT(dir); 22341da177e4SLinus Torvalds 22351b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 22361da177e4SLinus Torvalds dentry_unhash(dentry); 22371da177e4SLinus Torvalds if (d_mountpoint(dentry)) 22381da177e4SLinus Torvalds error = -EBUSY; 22391da177e4SLinus Torvalds else { 22401da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 22411da177e4SLinus Torvalds if (!error) { 22421da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 22431da177e4SLinus Torvalds if (!error) 22441da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 22451da177e4SLinus Torvalds } 22461da177e4SLinus Torvalds } 22471b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 22481da177e4SLinus Torvalds if (!error) { 22491da177e4SLinus Torvalds d_delete(dentry); 22501da177e4SLinus Torvalds } 22511da177e4SLinus Torvalds dput(dentry); 22521da177e4SLinus Torvalds 22531da177e4SLinus Torvalds return error; 22541da177e4SLinus Torvalds } 22551da177e4SLinus Torvalds 22565590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 22571da177e4SLinus Torvalds { 22581da177e4SLinus Torvalds int error = 0; 22591da177e4SLinus Torvalds char * name; 22601da177e4SLinus Torvalds struct dentry *dentry; 22611da177e4SLinus Torvalds struct nameidata nd; 22621da177e4SLinus Torvalds 22631da177e4SLinus Torvalds name = getname(pathname); 22641da177e4SLinus Torvalds if(IS_ERR(name)) 22651da177e4SLinus Torvalds return PTR_ERR(name); 22661da177e4SLinus Torvalds 22675590ff0dSUlrich Drepper error = do_path_lookup(dfd, name, LOOKUP_PARENT, &nd); 22681da177e4SLinus Torvalds if (error) 22691da177e4SLinus Torvalds goto exit; 22701da177e4SLinus Torvalds 22711da177e4SLinus Torvalds switch(nd.last_type) { 22721da177e4SLinus Torvalds case LAST_DOTDOT: 22731da177e4SLinus Torvalds error = -ENOTEMPTY; 22741da177e4SLinus Torvalds goto exit1; 22751da177e4SLinus Torvalds case LAST_DOT: 22761da177e4SLinus Torvalds error = -EINVAL; 22771da177e4SLinus Torvalds goto exit1; 22781da177e4SLinus Torvalds case LAST_ROOT: 22791da177e4SLinus Torvalds error = -EBUSY; 22801da177e4SLinus Torvalds goto exit1; 22811da177e4SLinus Torvalds } 22824ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 228349705b77SChristoph Hellwig dentry = lookup_hash(&nd); 22841da177e4SLinus Torvalds error = PTR_ERR(dentry); 22856902d925SDave Hansen if (IS_ERR(dentry)) 22866902d925SDave Hansen goto exit2; 22870622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 22880622753bSDave Hansen if (error) 22890622753bSDave Hansen goto exit3; 22904ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 22910622753bSDave Hansen mnt_drop_write(nd.path.mnt); 22920622753bSDave Hansen exit3: 22931da177e4SLinus Torvalds dput(dentry); 22946902d925SDave Hansen exit2: 22954ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 22961da177e4SLinus Torvalds exit1: 22971d957f9bSJan Blunck path_put(&nd.path); 22981da177e4SLinus Torvalds exit: 22991da177e4SLinus Torvalds putname(name); 23001da177e4SLinus Torvalds return error; 23011da177e4SLinus Torvalds } 23021da177e4SLinus Torvalds 23035590ff0dSUlrich Drepper asmlinkage long sys_rmdir(const char __user *pathname) 23045590ff0dSUlrich Drepper { 23055590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 23065590ff0dSUlrich Drepper } 23075590ff0dSUlrich Drepper 23081da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 23091da177e4SLinus Torvalds { 23101da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 23111da177e4SLinus Torvalds 23121da177e4SLinus Torvalds if (error) 23131da177e4SLinus Torvalds return error; 23141da177e4SLinus Torvalds 23151da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->unlink) 23161da177e4SLinus Torvalds return -EPERM; 23171da177e4SLinus Torvalds 23181da177e4SLinus Torvalds DQUOT_INIT(dir); 23191da177e4SLinus Torvalds 23201b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 23211da177e4SLinus Torvalds if (d_mountpoint(dentry)) 23221da177e4SLinus Torvalds error = -EBUSY; 23231da177e4SLinus Torvalds else { 23241da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 23251da177e4SLinus Torvalds if (!error) 23261da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 23271da177e4SLinus Torvalds } 23281b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 23291da177e4SLinus Torvalds 23301da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 23311da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2332ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 23331da177e4SLinus Torvalds d_delete(dentry); 23341da177e4SLinus Torvalds } 23350eeca283SRobert Love 23361da177e4SLinus Torvalds return error; 23371da177e4SLinus Torvalds } 23381da177e4SLinus Torvalds 23391da177e4SLinus Torvalds /* 23401da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 23411b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 23421da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 23431da177e4SLinus Torvalds * while waiting on the I/O. 23441da177e4SLinus Torvalds */ 23455590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 23461da177e4SLinus Torvalds { 23471da177e4SLinus Torvalds int error = 0; 23481da177e4SLinus Torvalds char * name; 23491da177e4SLinus Torvalds struct dentry *dentry; 23501da177e4SLinus Torvalds struct nameidata nd; 23511da177e4SLinus Torvalds struct inode *inode = NULL; 23521da177e4SLinus Torvalds 23531da177e4SLinus Torvalds name = getname(pathname); 23541da177e4SLinus Torvalds if(IS_ERR(name)) 23551da177e4SLinus Torvalds return PTR_ERR(name); 23561da177e4SLinus Torvalds 23575590ff0dSUlrich Drepper error = do_path_lookup(dfd, name, LOOKUP_PARENT, &nd); 23581da177e4SLinus Torvalds if (error) 23591da177e4SLinus Torvalds goto exit; 23601da177e4SLinus Torvalds error = -EISDIR; 23611da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 23621da177e4SLinus Torvalds goto exit1; 23634ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 236449705b77SChristoph Hellwig dentry = lookup_hash(&nd); 23651da177e4SLinus Torvalds error = PTR_ERR(dentry); 23661da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 23671da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 23681da177e4SLinus Torvalds if (nd.last.name[nd.last.len]) 23691da177e4SLinus Torvalds goto slashes; 23701da177e4SLinus Torvalds inode = dentry->d_inode; 23711da177e4SLinus Torvalds if (inode) 23721da177e4SLinus Torvalds atomic_inc(&inode->i_count); 23730622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 23740622753bSDave Hansen if (error) 23750622753bSDave Hansen goto exit2; 23764ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 23770622753bSDave Hansen mnt_drop_write(nd.path.mnt); 23781da177e4SLinus Torvalds exit2: 23791da177e4SLinus Torvalds dput(dentry); 23801da177e4SLinus Torvalds } 23814ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 23821da177e4SLinus Torvalds if (inode) 23831da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 23841da177e4SLinus Torvalds exit1: 23851d957f9bSJan Blunck path_put(&nd.path); 23861da177e4SLinus Torvalds exit: 23871da177e4SLinus Torvalds putname(name); 23881da177e4SLinus Torvalds return error; 23891da177e4SLinus Torvalds 23901da177e4SLinus Torvalds slashes: 23911da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 23921da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 23931da177e4SLinus Torvalds goto exit2; 23941da177e4SLinus Torvalds } 23951da177e4SLinus Torvalds 23965590ff0dSUlrich Drepper asmlinkage long sys_unlinkat(int dfd, const char __user *pathname, int flag) 23975590ff0dSUlrich Drepper { 23985590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 23995590ff0dSUlrich Drepper return -EINVAL; 24005590ff0dSUlrich Drepper 24015590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 24025590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 24035590ff0dSUlrich Drepper 24045590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 24055590ff0dSUlrich Drepper } 24065590ff0dSUlrich Drepper 24075590ff0dSUlrich Drepper asmlinkage long sys_unlink(const char __user *pathname) 24085590ff0dSUlrich Drepper { 24095590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 24105590ff0dSUlrich Drepper } 24115590ff0dSUlrich Drepper 24121da177e4SLinus Torvalds int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname, int mode) 24131da177e4SLinus Torvalds { 24141da177e4SLinus Torvalds int error = may_create(dir, dentry, NULL); 24151da177e4SLinus Torvalds 24161da177e4SLinus Torvalds if (error) 24171da177e4SLinus Torvalds return error; 24181da177e4SLinus Torvalds 24191da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->symlink) 24201da177e4SLinus Torvalds return -EPERM; 24211da177e4SLinus Torvalds 24221da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 24231da177e4SLinus Torvalds if (error) 24241da177e4SLinus Torvalds return error; 24251da177e4SLinus Torvalds 24261da177e4SLinus Torvalds DQUOT_INIT(dir); 24271da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2428a74574aaSStephen Smalley if (!error) 2429f38aa942SAmy Griffis fsnotify_create(dir, dentry); 24301da177e4SLinus Torvalds return error; 24311da177e4SLinus Torvalds } 24321da177e4SLinus Torvalds 24335590ff0dSUlrich Drepper asmlinkage long sys_symlinkat(const char __user *oldname, 24345590ff0dSUlrich Drepper int newdfd, const char __user *newname) 24351da177e4SLinus Torvalds { 24361da177e4SLinus Torvalds int error = 0; 24371da177e4SLinus Torvalds char * from; 24381da177e4SLinus Torvalds char * to; 24396902d925SDave Hansen struct dentry *dentry; 24406902d925SDave Hansen struct nameidata nd; 24411da177e4SLinus Torvalds 24421da177e4SLinus Torvalds from = getname(oldname); 24431da177e4SLinus Torvalds if(IS_ERR(from)) 24441da177e4SLinus Torvalds return PTR_ERR(from); 24451da177e4SLinus Torvalds to = getname(newname); 24461da177e4SLinus Torvalds error = PTR_ERR(to); 24476902d925SDave Hansen if (IS_ERR(to)) 24486902d925SDave Hansen goto out_putname; 24491da177e4SLinus Torvalds 24505590ff0dSUlrich Drepper error = do_path_lookup(newdfd, to, LOOKUP_PARENT, &nd); 24511da177e4SLinus Torvalds if (error) 24521da177e4SLinus Torvalds goto out; 24531da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 24541da177e4SLinus Torvalds error = PTR_ERR(dentry); 24556902d925SDave Hansen if (IS_ERR(dentry)) 24566902d925SDave Hansen goto out_unlock; 24576902d925SDave Hansen 245875c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 245975c3f29dSDave Hansen if (error) 246075c3f29dSDave Hansen goto out_dput; 24614ac91378SJan Blunck error = vfs_symlink(nd.path.dentry->d_inode, dentry, from, S_IALLUGO); 246275c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 246375c3f29dSDave Hansen out_dput: 24641da177e4SLinus Torvalds dput(dentry); 24656902d925SDave Hansen out_unlock: 24664ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 24671d957f9bSJan Blunck path_put(&nd.path); 24681da177e4SLinus Torvalds out: 24691da177e4SLinus Torvalds putname(to); 24706902d925SDave Hansen out_putname: 24711da177e4SLinus Torvalds putname(from); 24721da177e4SLinus Torvalds return error; 24731da177e4SLinus Torvalds } 24741da177e4SLinus Torvalds 24755590ff0dSUlrich Drepper asmlinkage long sys_symlink(const char __user *oldname, const char __user *newname) 24765590ff0dSUlrich Drepper { 24775590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 24785590ff0dSUlrich Drepper } 24795590ff0dSUlrich Drepper 24801da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 24811da177e4SLinus Torvalds { 24821da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 24831da177e4SLinus Torvalds int error; 24841da177e4SLinus Torvalds 24851da177e4SLinus Torvalds if (!inode) 24861da177e4SLinus Torvalds return -ENOENT; 24871da177e4SLinus Torvalds 24881da177e4SLinus Torvalds error = may_create(dir, new_dentry, NULL); 24891da177e4SLinus Torvalds if (error) 24901da177e4SLinus Torvalds return error; 24911da177e4SLinus Torvalds 24921da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 24931da177e4SLinus Torvalds return -EXDEV; 24941da177e4SLinus Torvalds 24951da177e4SLinus Torvalds /* 24961da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 24971da177e4SLinus Torvalds */ 24981da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 24991da177e4SLinus Torvalds return -EPERM; 25001da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->link) 25011da177e4SLinus Torvalds return -EPERM; 25021da177e4SLinus Torvalds if (S_ISDIR(old_dentry->d_inode->i_mode)) 25031da177e4SLinus Torvalds return -EPERM; 25041da177e4SLinus Torvalds 25051da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 25061da177e4SLinus Torvalds if (error) 25071da177e4SLinus Torvalds return error; 25081da177e4SLinus Torvalds 25091b1dcc1bSJes Sorensen mutex_lock(&old_dentry->d_inode->i_mutex); 25101da177e4SLinus Torvalds DQUOT_INIT(dir); 25111da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 25121b1dcc1bSJes Sorensen mutex_unlock(&old_dentry->d_inode->i_mutex); 2513e31e14ecSStephen Smalley if (!error) 2514ece95912SJan Kara fsnotify_link(dir, old_dentry->d_inode, new_dentry); 25151da177e4SLinus Torvalds return error; 25161da177e4SLinus Torvalds } 25171da177e4SLinus Torvalds 25181da177e4SLinus Torvalds /* 25191da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 25201da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 25211da177e4SLinus Torvalds * newname. --KAB 25221da177e4SLinus Torvalds * 25231da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 25241da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 25251da177e4SLinus Torvalds * and other special files. --ADM 25261da177e4SLinus Torvalds */ 25275590ff0dSUlrich Drepper asmlinkage long sys_linkat(int olddfd, const char __user *oldname, 2528c04030e1SUlrich Drepper int newdfd, const char __user *newname, 2529c04030e1SUlrich Drepper int flags) 25301da177e4SLinus Torvalds { 25311da177e4SLinus Torvalds struct dentry *new_dentry; 25321da177e4SLinus Torvalds struct nameidata nd, old_nd; 25331da177e4SLinus Torvalds int error; 25341da177e4SLinus Torvalds char * to; 25351da177e4SLinus Torvalds 253645c9b11aSUlrich Drepper if ((flags & ~AT_SYMLINK_FOLLOW) != 0) 2537c04030e1SUlrich Drepper return -EINVAL; 2538c04030e1SUlrich Drepper 25391da177e4SLinus Torvalds to = getname(newname); 25401da177e4SLinus Torvalds if (IS_ERR(to)) 25411da177e4SLinus Torvalds return PTR_ERR(to); 25421da177e4SLinus Torvalds 254345c9b11aSUlrich Drepper error = __user_walk_fd(olddfd, oldname, 254445c9b11aSUlrich Drepper flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0, 254545c9b11aSUlrich Drepper &old_nd); 25461da177e4SLinus Torvalds if (error) 25471da177e4SLinus Torvalds goto exit; 25485590ff0dSUlrich Drepper error = do_path_lookup(newdfd, to, LOOKUP_PARENT, &nd); 25491da177e4SLinus Torvalds if (error) 25501da177e4SLinus Torvalds goto out; 25511da177e4SLinus Torvalds error = -EXDEV; 25524ac91378SJan Blunck if (old_nd.path.mnt != nd.path.mnt) 25531da177e4SLinus Torvalds goto out_release; 25541da177e4SLinus Torvalds new_dentry = lookup_create(&nd, 0); 25551da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 25566902d925SDave Hansen if (IS_ERR(new_dentry)) 25576902d925SDave Hansen goto out_unlock; 255875c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 255975c3f29dSDave Hansen if (error) 256075c3f29dSDave Hansen goto out_dput; 25614ac91378SJan Blunck error = vfs_link(old_nd.path.dentry, nd.path.dentry->d_inode, new_dentry); 256275c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 256375c3f29dSDave Hansen out_dput: 25641da177e4SLinus Torvalds dput(new_dentry); 25656902d925SDave Hansen out_unlock: 25664ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 25671da177e4SLinus Torvalds out_release: 25681d957f9bSJan Blunck path_put(&nd.path); 25691da177e4SLinus Torvalds out: 25701d957f9bSJan Blunck path_put(&old_nd.path); 25711da177e4SLinus Torvalds exit: 25721da177e4SLinus Torvalds putname(to); 25731da177e4SLinus Torvalds 25741da177e4SLinus Torvalds return error; 25751da177e4SLinus Torvalds } 25761da177e4SLinus Torvalds 25775590ff0dSUlrich Drepper asmlinkage long sys_link(const char __user *oldname, const char __user *newname) 25785590ff0dSUlrich Drepper { 2579c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 25805590ff0dSUlrich Drepper } 25815590ff0dSUlrich Drepper 25821da177e4SLinus Torvalds /* 25831da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 25841da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 25851da177e4SLinus Torvalds * Problems: 25861da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 25871da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 25881da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 2589a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 25901da177e4SLinus Torvalds * story. 25911da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 25921b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 25931da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 25941da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 2595a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 25961da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 25971da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 25981da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 2599a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 26001da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 26011da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 26021da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 26031da177e4SLinus Torvalds * d) some filesystems don't support opened-but-unlinked directories, 26041da177e4SLinus Torvalds * either because of layout or because they are not ready to deal with 26051da177e4SLinus Torvalds * all cases correctly. The latter will be fixed (taking this sort of 26061da177e4SLinus Torvalds * stuff into VFS), but the former is not going away. Solution: the same 26071da177e4SLinus Torvalds * trick as in rmdir(). 26081da177e4SLinus Torvalds * e) conversion from fhandle to dentry may come in the wrong moment - when 26091b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 26101da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 26111b1dcc1bSJes Sorensen * ->i_mutex on parents, which works but leads to some truely excessive 26121da177e4SLinus Torvalds * locking]. 26131da177e4SLinus Torvalds */ 261475c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 26151da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 26161da177e4SLinus Torvalds { 26171da177e4SLinus Torvalds int error = 0; 26181da177e4SLinus Torvalds struct inode *target; 26191da177e4SLinus Torvalds 26201da177e4SLinus Torvalds /* 26211da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 26221da177e4SLinus Torvalds * we'll need to flip '..'. 26231da177e4SLinus Torvalds */ 26241da177e4SLinus Torvalds if (new_dir != old_dir) { 26251da177e4SLinus Torvalds error = permission(old_dentry->d_inode, MAY_WRITE, NULL); 26261da177e4SLinus Torvalds if (error) 26271da177e4SLinus Torvalds return error; 26281da177e4SLinus Torvalds } 26291da177e4SLinus Torvalds 26301da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 26311da177e4SLinus Torvalds if (error) 26321da177e4SLinus Torvalds return error; 26331da177e4SLinus Torvalds 26341da177e4SLinus Torvalds target = new_dentry->d_inode; 26351da177e4SLinus Torvalds if (target) { 26361b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 26371da177e4SLinus Torvalds dentry_unhash(new_dentry); 26381da177e4SLinus Torvalds } 26391da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 26401da177e4SLinus Torvalds error = -EBUSY; 26411da177e4SLinus Torvalds else 26421da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 26431da177e4SLinus Torvalds if (target) { 26441da177e4SLinus Torvalds if (!error) 26451da177e4SLinus Torvalds target->i_flags |= S_DEAD; 26461b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 26471da177e4SLinus Torvalds if (d_unhashed(new_dentry)) 26481da177e4SLinus Torvalds d_rehash(new_dentry); 26491da177e4SLinus Torvalds dput(new_dentry); 26501da177e4SLinus Torvalds } 2651e31e14ecSStephen Smalley if (!error) 2652349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 26531da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 26541da177e4SLinus Torvalds return error; 26551da177e4SLinus Torvalds } 26561da177e4SLinus Torvalds 265775c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 26581da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 26591da177e4SLinus Torvalds { 26601da177e4SLinus Torvalds struct inode *target; 26611da177e4SLinus Torvalds int error; 26621da177e4SLinus Torvalds 26631da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 26641da177e4SLinus Torvalds if (error) 26651da177e4SLinus Torvalds return error; 26661da177e4SLinus Torvalds 26671da177e4SLinus Torvalds dget(new_dentry); 26681da177e4SLinus Torvalds target = new_dentry->d_inode; 26691da177e4SLinus Torvalds if (target) 26701b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 26711da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 26721da177e4SLinus Torvalds error = -EBUSY; 26731da177e4SLinus Torvalds else 26741da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 26751da177e4SLinus Torvalds if (!error) { 2676349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 26771da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 26781da177e4SLinus Torvalds } 26791da177e4SLinus Torvalds if (target) 26801b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 26811da177e4SLinus Torvalds dput(new_dentry); 26821da177e4SLinus Torvalds return error; 26831da177e4SLinus Torvalds } 26841da177e4SLinus Torvalds 26851da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 26861da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 26871da177e4SLinus Torvalds { 26881da177e4SLinus Torvalds int error; 26891da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 26900eeca283SRobert Love const char *old_name; 26911da177e4SLinus Torvalds 26921da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 26931da177e4SLinus Torvalds return 0; 26941da177e4SLinus Torvalds 26951da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 26961da177e4SLinus Torvalds if (error) 26971da177e4SLinus Torvalds return error; 26981da177e4SLinus Torvalds 26991da177e4SLinus Torvalds if (!new_dentry->d_inode) 27001da177e4SLinus Torvalds error = may_create(new_dir, new_dentry, NULL); 27011da177e4SLinus Torvalds else 27021da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 27031da177e4SLinus Torvalds if (error) 27041da177e4SLinus Torvalds return error; 27051da177e4SLinus Torvalds 27061da177e4SLinus Torvalds if (!old_dir->i_op || !old_dir->i_op->rename) 27071da177e4SLinus Torvalds return -EPERM; 27081da177e4SLinus Torvalds 27091da177e4SLinus Torvalds DQUOT_INIT(old_dir); 27101da177e4SLinus Torvalds DQUOT_INIT(new_dir); 27111da177e4SLinus Torvalds 27120eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 27130eeca283SRobert Love 27141da177e4SLinus Torvalds if (is_dir) 27151da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 27161da177e4SLinus Torvalds else 27171da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 27181da177e4SLinus Torvalds if (!error) { 27190eeca283SRobert Love const char *new_name = old_dentry->d_name.name; 272089204c40SJohn McCutchan fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir, 27215a190ae6SAl Viro new_dentry->d_inode, old_dentry); 27221da177e4SLinus Torvalds } 27230eeca283SRobert Love fsnotify_oldname_free(old_name); 27240eeca283SRobert Love 27251da177e4SLinus Torvalds return error; 27261da177e4SLinus Torvalds } 27271da177e4SLinus Torvalds 27285590ff0dSUlrich Drepper static int do_rename(int olddfd, const char *oldname, 27295590ff0dSUlrich Drepper int newdfd, const char *newname) 27301da177e4SLinus Torvalds { 27311da177e4SLinus Torvalds int error = 0; 27321da177e4SLinus Torvalds struct dentry * old_dir, * new_dir; 27331da177e4SLinus Torvalds struct dentry * old_dentry, *new_dentry; 27341da177e4SLinus Torvalds struct dentry * trap; 27351da177e4SLinus Torvalds struct nameidata oldnd, newnd; 27361da177e4SLinus Torvalds 27375590ff0dSUlrich Drepper error = do_path_lookup(olddfd, oldname, LOOKUP_PARENT, &oldnd); 27381da177e4SLinus Torvalds if (error) 27391da177e4SLinus Torvalds goto exit; 27401da177e4SLinus Torvalds 27415590ff0dSUlrich Drepper error = do_path_lookup(newdfd, newname, LOOKUP_PARENT, &newnd); 27421da177e4SLinus Torvalds if (error) 27431da177e4SLinus Torvalds goto exit1; 27441da177e4SLinus Torvalds 27451da177e4SLinus Torvalds error = -EXDEV; 27464ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 27471da177e4SLinus Torvalds goto exit2; 27481da177e4SLinus Torvalds 27494ac91378SJan Blunck old_dir = oldnd.path.dentry; 27501da177e4SLinus Torvalds error = -EBUSY; 27511da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 27521da177e4SLinus Torvalds goto exit2; 27531da177e4SLinus Torvalds 27544ac91378SJan Blunck new_dir = newnd.path.dentry; 27551da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 27561da177e4SLinus Torvalds goto exit2; 27571da177e4SLinus Torvalds 27581da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 27591da177e4SLinus Torvalds 276049705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 27611da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 27621da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 27631da177e4SLinus Torvalds goto exit3; 27641da177e4SLinus Torvalds /* source must exist */ 27651da177e4SLinus Torvalds error = -ENOENT; 27661da177e4SLinus Torvalds if (!old_dentry->d_inode) 27671da177e4SLinus Torvalds goto exit4; 27681da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 27691da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 27701da177e4SLinus Torvalds error = -ENOTDIR; 27711da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 27721da177e4SLinus Torvalds goto exit4; 27731da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 27741da177e4SLinus Torvalds goto exit4; 27751da177e4SLinus Torvalds } 27761da177e4SLinus Torvalds /* source should not be ancestor of target */ 27771da177e4SLinus Torvalds error = -EINVAL; 27781da177e4SLinus Torvalds if (old_dentry == trap) 27791da177e4SLinus Torvalds goto exit4; 278049705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 27811da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 27821da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 27831da177e4SLinus Torvalds goto exit4; 27841da177e4SLinus Torvalds /* target should not be an ancestor of source */ 27851da177e4SLinus Torvalds error = -ENOTEMPTY; 27861da177e4SLinus Torvalds if (new_dentry == trap) 27871da177e4SLinus Torvalds goto exit5; 27881da177e4SLinus Torvalds 27899079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 27909079b1ebSDave Hansen if (error) 27919079b1ebSDave Hansen goto exit5; 27921da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 27931da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 27949079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 27951da177e4SLinus Torvalds exit5: 27961da177e4SLinus Torvalds dput(new_dentry); 27971da177e4SLinus Torvalds exit4: 27981da177e4SLinus Torvalds dput(old_dentry); 27991da177e4SLinus Torvalds exit3: 28001da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 28011da177e4SLinus Torvalds exit2: 28021d957f9bSJan Blunck path_put(&newnd.path); 28031da177e4SLinus Torvalds exit1: 28041d957f9bSJan Blunck path_put(&oldnd.path); 28051da177e4SLinus Torvalds exit: 28061da177e4SLinus Torvalds return error; 28071da177e4SLinus Torvalds } 28081da177e4SLinus Torvalds 28095590ff0dSUlrich Drepper asmlinkage long sys_renameat(int olddfd, const char __user *oldname, 28105590ff0dSUlrich Drepper int newdfd, const char __user *newname) 28111da177e4SLinus Torvalds { 28121da177e4SLinus Torvalds int error; 28131da177e4SLinus Torvalds char * from; 28141da177e4SLinus Torvalds char * to; 28151da177e4SLinus Torvalds 28161da177e4SLinus Torvalds from = getname(oldname); 28171da177e4SLinus Torvalds if(IS_ERR(from)) 28181da177e4SLinus Torvalds return PTR_ERR(from); 28191da177e4SLinus Torvalds to = getname(newname); 28201da177e4SLinus Torvalds error = PTR_ERR(to); 28211da177e4SLinus Torvalds if (!IS_ERR(to)) { 28225590ff0dSUlrich Drepper error = do_rename(olddfd, from, newdfd, to); 28231da177e4SLinus Torvalds putname(to); 28241da177e4SLinus Torvalds } 28251da177e4SLinus Torvalds putname(from); 28261da177e4SLinus Torvalds return error; 28271da177e4SLinus Torvalds } 28281da177e4SLinus Torvalds 28295590ff0dSUlrich Drepper asmlinkage long sys_rename(const char __user *oldname, const char __user *newname) 28305590ff0dSUlrich Drepper { 28315590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 28325590ff0dSUlrich Drepper } 28335590ff0dSUlrich Drepper 28341da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 28351da177e4SLinus Torvalds { 28361da177e4SLinus Torvalds int len; 28371da177e4SLinus Torvalds 28381da177e4SLinus Torvalds len = PTR_ERR(link); 28391da177e4SLinus Torvalds if (IS_ERR(link)) 28401da177e4SLinus Torvalds goto out; 28411da177e4SLinus Torvalds 28421da177e4SLinus Torvalds len = strlen(link); 28431da177e4SLinus Torvalds if (len > (unsigned) buflen) 28441da177e4SLinus Torvalds len = buflen; 28451da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 28461da177e4SLinus Torvalds len = -EFAULT; 28471da177e4SLinus Torvalds out: 28481da177e4SLinus Torvalds return len; 28491da177e4SLinus Torvalds } 28501da177e4SLinus Torvalds 28511da177e4SLinus Torvalds /* 28521da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 28531da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 28541da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 28551da177e4SLinus Torvalds */ 28561da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 28571da177e4SLinus Torvalds { 28581da177e4SLinus Torvalds struct nameidata nd; 2859cc314eefSLinus Torvalds void *cookie; 2860cc314eefSLinus Torvalds 28611da177e4SLinus Torvalds nd.depth = 0; 2862cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 2863cc314eefSLinus Torvalds if (!IS_ERR(cookie)) { 2864cc314eefSLinus Torvalds int res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 28651da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 2866cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 2867cc314eefSLinus Torvalds cookie = ERR_PTR(res); 28681da177e4SLinus Torvalds } 2869cc314eefSLinus Torvalds return PTR_ERR(cookie); 28701da177e4SLinus Torvalds } 28711da177e4SLinus Torvalds 28721da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 28731da177e4SLinus Torvalds { 28741da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 28751da177e4SLinus Torvalds } 28761da177e4SLinus Torvalds 28771da177e4SLinus Torvalds /* get the link contents into pagecache */ 28781da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 28791da177e4SLinus Torvalds { 28801da177e4SLinus Torvalds struct page * page; 28811da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 2882090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 28831da177e4SLinus Torvalds if (IS_ERR(page)) 28846fe6900eSNick Piggin return (char*)page; 28851da177e4SLinus Torvalds *ppage = page; 28861da177e4SLinus Torvalds return kmap(page); 28871da177e4SLinus Torvalds } 28881da177e4SLinus Torvalds 28891da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 28901da177e4SLinus Torvalds { 28911da177e4SLinus Torvalds struct page *page = NULL; 28921da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 28931da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 28941da177e4SLinus Torvalds if (page) { 28951da177e4SLinus Torvalds kunmap(page); 28961da177e4SLinus Torvalds page_cache_release(page); 28971da177e4SLinus Torvalds } 28981da177e4SLinus Torvalds return res; 28991da177e4SLinus Torvalds } 29001da177e4SLinus Torvalds 2901cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 29021da177e4SLinus Torvalds { 2903cc314eefSLinus Torvalds struct page *page = NULL; 29041da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 2905cc314eefSLinus Torvalds return page; 29061da177e4SLinus Torvalds } 29071da177e4SLinus Torvalds 2908cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 29091da177e4SLinus Torvalds { 2910cc314eefSLinus Torvalds struct page *page = cookie; 2911cc314eefSLinus Torvalds 2912cc314eefSLinus Torvalds if (page) { 29131da177e4SLinus Torvalds kunmap(page); 29141da177e4SLinus Torvalds page_cache_release(page); 29151da177e4SLinus Torvalds } 29161da177e4SLinus Torvalds } 29171da177e4SLinus Torvalds 29180adb25d2SKirill Korotaev int __page_symlink(struct inode *inode, const char *symname, int len, 29190adb25d2SKirill Korotaev gfp_t gfp_mask) 29201da177e4SLinus Torvalds { 29211da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 29220adb25d2SKirill Korotaev struct page *page; 2923afddba49SNick Piggin void *fsdata; 2924beb497abSDmitriy Monakhov int err; 29251da177e4SLinus Torvalds char *kaddr; 29261da177e4SLinus Torvalds 29277e53cac4SNeilBrown retry: 2928afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 2929afddba49SNick Piggin AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata); 29301da177e4SLinus Torvalds if (err) 2931afddba49SNick Piggin goto fail; 2932afddba49SNick Piggin 29331da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 29341da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 29351da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 2936afddba49SNick Piggin 2937afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 2938afddba49SNick Piggin page, fsdata); 29391da177e4SLinus Torvalds if (err < 0) 29401da177e4SLinus Torvalds goto fail; 2941afddba49SNick Piggin if (err < len-1) 2942afddba49SNick Piggin goto retry; 2943afddba49SNick Piggin 29441da177e4SLinus Torvalds mark_inode_dirty(inode); 29451da177e4SLinus Torvalds return 0; 29461da177e4SLinus Torvalds fail: 29471da177e4SLinus Torvalds return err; 29481da177e4SLinus Torvalds } 29491da177e4SLinus Torvalds 29500adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 29510adb25d2SKirill Korotaev { 29520adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 29530adb25d2SKirill Korotaev mapping_gfp_mask(inode->i_mapping)); 29540adb25d2SKirill Korotaev } 29550adb25d2SKirill Korotaev 295692e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 29571da177e4SLinus Torvalds .readlink = generic_readlink, 29581da177e4SLinus Torvalds .follow_link = page_follow_link_light, 29591da177e4SLinus Torvalds .put_link = page_put_link, 29601da177e4SLinus Torvalds }; 29611da177e4SLinus Torvalds 29621da177e4SLinus Torvalds EXPORT_SYMBOL(__user_walk); 29635590ff0dSUlrich Drepper EXPORT_SYMBOL(__user_walk_fd); 29641da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 29651da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 29661da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 29671da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 29681da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 29691da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 29701da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 29711da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 29721da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 29730adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 29741da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 29751da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 29761da177e4SLinus Torvalds EXPORT_SYMBOL(path_lookup); 297716f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 29781da177e4SLinus Torvalds EXPORT_SYMBOL(permission); 2979e4543eddSChristoph Hellwig EXPORT_SYMBOL(vfs_permission); 29808c744fb8SChristoph Hellwig EXPORT_SYMBOL(file_permission); 29811da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 29821da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 29831da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 29841da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 29851da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 29861da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 29871da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 29881da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 29891da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 29901da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 29911da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 29921da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 29931da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 29941da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 2995