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> 276146f0d5SMimi Zohar #include <linux/ima.h> 281da177e4SLinus Torvalds #include <linux/syscalls.h> 291da177e4SLinus Torvalds #include <linux/mount.h> 301da177e4SLinus Torvalds #include <linux/audit.h> 3116f7e0feSRandy Dunlap #include <linux/capability.h> 32834f2a4aSTrond Myklebust #include <linux/file.h> 335590ff0dSUlrich Drepper #include <linux/fcntl.h> 3408ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 355ad4e53bSAl Viro #include <linux/fs_struct.h> 361da177e4SLinus Torvalds #include <asm/uaccess.h> 371da177e4SLinus Torvalds 381da177e4SLinus Torvalds #define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE]) 391da177e4SLinus Torvalds 401da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 411da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 421da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 431da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 441da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 451da177e4SLinus Torvalds * 461da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 471da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 481da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 491da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 501da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 511da177e4SLinus Torvalds * the special cases of the former code. 521da177e4SLinus Torvalds * 531da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 541da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 551da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 561da177e4SLinus Torvalds * 571da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 581da177e4SLinus Torvalds * resolution to correspond with current state of the code. 591da177e4SLinus Torvalds * 601da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 611da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 621da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 631da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 641da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 651da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 661da177e4SLinus Torvalds */ 671da177e4SLinus Torvalds 681da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 691da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 701da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 711da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 721da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 731da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 741da177e4SLinus Torvalds * the name is a symlink pointing to a non-existant name. 751da177e4SLinus Torvalds * 761da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 771da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 781da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 791da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 801da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 811da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 821da177e4SLinus Torvalds * and in the old Linux semantics. 831da177e4SLinus Torvalds */ 841da177e4SLinus Torvalds 851da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 861da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 871da177e4SLinus Torvalds * 881da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 891da177e4SLinus Torvalds */ 901da177e4SLinus Torvalds 911da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 921da177e4SLinus Torvalds * inside the path - always follow. 931da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 941da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 951da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 961da177e4SLinus Torvalds * otherwise - don't follow. 971da177e4SLinus Torvalds * (applied in that order). 981da177e4SLinus Torvalds * 991da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1001da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1011da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1021da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1031da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1041da177e4SLinus Torvalds */ 1051da177e4SLinus Torvalds /* 1061da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 107a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1081da177e4SLinus Torvalds * any extra contention... 1091da177e4SLinus Torvalds */ 1101da177e4SLinus Torvalds 111a02f76c3SAl Viro static int __link_path_walk(const char *name, struct nameidata *nd); 112c4a7808fSJosef 'Jeff' Sipek 1131da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1141da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1151da177e4SLinus Torvalds * kernel data space before using them.. 1161da177e4SLinus Torvalds * 1171da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1181da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1191da177e4SLinus Torvalds */ 120858119e1SArjan van de Ven static int do_getname(const char __user *filename, char *page) 1211da177e4SLinus Torvalds { 1221da177e4SLinus Torvalds int retval; 1231da177e4SLinus Torvalds unsigned long len = PATH_MAX; 1241da177e4SLinus Torvalds 1251da177e4SLinus Torvalds if (!segment_eq(get_fs(), KERNEL_DS)) { 1261da177e4SLinus Torvalds if ((unsigned long) filename >= TASK_SIZE) 1271da177e4SLinus Torvalds return -EFAULT; 1281da177e4SLinus Torvalds if (TASK_SIZE - (unsigned long) filename < PATH_MAX) 1291da177e4SLinus Torvalds len = TASK_SIZE - (unsigned long) filename; 1301da177e4SLinus Torvalds } 1311da177e4SLinus Torvalds 1321da177e4SLinus Torvalds retval = strncpy_from_user(page, filename, len); 1331da177e4SLinus Torvalds if (retval > 0) { 1341da177e4SLinus Torvalds if (retval < len) 1351da177e4SLinus Torvalds return 0; 1361da177e4SLinus Torvalds return -ENAMETOOLONG; 1371da177e4SLinus Torvalds } else if (!retval) 1381da177e4SLinus Torvalds retval = -ENOENT; 1391da177e4SLinus Torvalds return retval; 1401da177e4SLinus Torvalds } 1411da177e4SLinus Torvalds 1421da177e4SLinus Torvalds char * getname(const char __user * filename) 1431da177e4SLinus Torvalds { 1441da177e4SLinus Torvalds char *tmp, *result; 1451da177e4SLinus Torvalds 1461da177e4SLinus Torvalds result = ERR_PTR(-ENOMEM); 1471da177e4SLinus Torvalds tmp = __getname(); 1481da177e4SLinus Torvalds if (tmp) { 1491da177e4SLinus Torvalds int retval = do_getname(filename, tmp); 1501da177e4SLinus Torvalds 1511da177e4SLinus Torvalds result = tmp; 1521da177e4SLinus Torvalds if (retval < 0) { 1531da177e4SLinus Torvalds __putname(tmp); 1541da177e4SLinus Torvalds result = ERR_PTR(retval); 1551da177e4SLinus Torvalds } 1561da177e4SLinus Torvalds } 1571da177e4SLinus Torvalds audit_getname(result); 1581da177e4SLinus Torvalds return result; 1591da177e4SLinus Torvalds } 1601da177e4SLinus Torvalds 1611da177e4SLinus Torvalds #ifdef CONFIG_AUDITSYSCALL 1621da177e4SLinus Torvalds void putname(const char *name) 1631da177e4SLinus Torvalds { 1645ac3a9c2SAl Viro if (unlikely(!audit_dummy_context())) 1651da177e4SLinus Torvalds audit_putname(name); 1661da177e4SLinus Torvalds else 1671da177e4SLinus Torvalds __putname(name); 1681da177e4SLinus Torvalds } 1691da177e4SLinus Torvalds EXPORT_SYMBOL(putname); 1701da177e4SLinus Torvalds #endif 1711da177e4SLinus Torvalds 1721da177e4SLinus Torvalds 1731da177e4SLinus Torvalds /** 1741da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 1751da177e4SLinus Torvalds * @inode: inode to check access rights for 1761da177e4SLinus Torvalds * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 1771da177e4SLinus Torvalds * @check_acl: optional callback to check for Posix ACLs 1781da177e4SLinus Torvalds * 1791da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 1801da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 1811da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 1821da177e4SLinus Torvalds * are used for other things.. 1831da177e4SLinus Torvalds */ 1841da177e4SLinus Torvalds int generic_permission(struct inode *inode, int mask, 1851da177e4SLinus Torvalds int (*check_acl)(struct inode *inode, int mask)) 1861da177e4SLinus Torvalds { 1871da177e4SLinus Torvalds umode_t mode = inode->i_mode; 1881da177e4SLinus Torvalds 189e6305c43SAl Viro mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 190e6305c43SAl Viro 191da9592edSDavid Howells if (current_fsuid() == inode->i_uid) 1921da177e4SLinus Torvalds mode >>= 6; 1931da177e4SLinus Torvalds else { 1941da177e4SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) { 1951da177e4SLinus Torvalds int error = check_acl(inode, mask); 1961da177e4SLinus Torvalds if (error == -EACCES) 1971da177e4SLinus Torvalds goto check_capabilities; 1981da177e4SLinus Torvalds else if (error != -EAGAIN) 1991da177e4SLinus Torvalds return error; 2001da177e4SLinus Torvalds } 2011da177e4SLinus Torvalds 2021da177e4SLinus Torvalds if (in_group_p(inode->i_gid)) 2031da177e4SLinus Torvalds mode >>= 3; 2041da177e4SLinus Torvalds } 2051da177e4SLinus Torvalds 2061da177e4SLinus Torvalds /* 2071da177e4SLinus Torvalds * If the DACs are ok we don't need any capability check. 2081da177e4SLinus Torvalds */ 209e6305c43SAl Viro if ((mask & ~mode) == 0) 2101da177e4SLinus Torvalds return 0; 2111da177e4SLinus Torvalds 2121da177e4SLinus Torvalds check_capabilities: 2131da177e4SLinus Torvalds /* 2141da177e4SLinus Torvalds * Read/write DACs are always overridable. 2151da177e4SLinus Torvalds * Executable DACs are overridable if at least one exec bit is set. 2161da177e4SLinus Torvalds */ 217f696a365SMiklos Szeredi if (!(mask & MAY_EXEC) || execute_ok(inode)) 2181da177e4SLinus Torvalds if (capable(CAP_DAC_OVERRIDE)) 2191da177e4SLinus Torvalds return 0; 2201da177e4SLinus Torvalds 2211da177e4SLinus Torvalds /* 2221da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 2231da177e4SLinus Torvalds */ 2241da177e4SLinus Torvalds if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))) 2251da177e4SLinus Torvalds if (capable(CAP_DAC_READ_SEARCH)) 2261da177e4SLinus Torvalds return 0; 2271da177e4SLinus Torvalds 2281da177e4SLinus Torvalds return -EACCES; 2291da177e4SLinus Torvalds } 2301da177e4SLinus Torvalds 231cb23beb5SChristoph Hellwig /** 232cb23beb5SChristoph Hellwig * inode_permission - check for access rights to a given inode 233cb23beb5SChristoph Hellwig * @inode: inode to check permission on 234cb23beb5SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 235cb23beb5SChristoph Hellwig * 236cb23beb5SChristoph Hellwig * Used to check for read/write/execute permissions on an inode. 237cb23beb5SChristoph Hellwig * We use "fsuid" for this, letting us set arbitrary permissions 238cb23beb5SChristoph Hellwig * for filesystem access without changing the "normal" uids which 239cb23beb5SChristoph Hellwig * are used for other things. 240cb23beb5SChristoph Hellwig */ 241f419a2e3SAl Viro int inode_permission(struct inode *inode, int mask) 2421da177e4SLinus Torvalds { 243e6305c43SAl Viro int retval; 2441da177e4SLinus Torvalds 2451da177e4SLinus Torvalds if (mask & MAY_WRITE) { 24622590e41SMiklos Szeredi umode_t mode = inode->i_mode; 2471da177e4SLinus Torvalds 2481da177e4SLinus Torvalds /* 2491da177e4SLinus Torvalds * Nobody gets write access to a read-only fs. 2501da177e4SLinus Torvalds */ 2511da177e4SLinus Torvalds if (IS_RDONLY(inode) && 2521da177e4SLinus Torvalds (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 2531da177e4SLinus Torvalds return -EROFS; 2541da177e4SLinus Torvalds 2551da177e4SLinus Torvalds /* 2561da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 2571da177e4SLinus Torvalds */ 2581da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 2591da177e4SLinus Torvalds return -EACCES; 2601da177e4SLinus Torvalds } 2611da177e4SLinus Torvalds 262acfa4380SAl Viro if (inode->i_op->permission) 263b77b0646SAl Viro retval = inode->i_op->permission(inode, mask); 264f696a365SMiklos Szeredi else 265e6305c43SAl Viro retval = generic_permission(inode, mask, NULL); 266f696a365SMiklos Szeredi 2671da177e4SLinus Torvalds if (retval) 2681da177e4SLinus Torvalds return retval; 2691da177e4SLinus Torvalds 27008ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 27108ce5f16SSerge E. Hallyn if (retval) 27208ce5f16SSerge E. Hallyn return retval; 27308ce5f16SSerge E. Hallyn 274e6305c43SAl Viro return security_inode_permission(inode, 275f418b006SStephen Smalley mask & (MAY_READ|MAY_WRITE|MAY_EXEC|MAY_APPEND)); 2761da177e4SLinus Torvalds } 2771da177e4SLinus Torvalds 278e4543eddSChristoph Hellwig /** 2798c744fb8SChristoph Hellwig * file_permission - check for additional access rights to a given file 2808c744fb8SChristoph Hellwig * @file: file to check access rights for 2818c744fb8SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 2828c744fb8SChristoph Hellwig * 2838c744fb8SChristoph Hellwig * Used to check for read/write/execute permissions on an already opened 2848c744fb8SChristoph Hellwig * file. 2858c744fb8SChristoph Hellwig * 2868c744fb8SChristoph Hellwig * Note: 2878c744fb8SChristoph Hellwig * Do not use this function in new code. All access checks should 288cb23beb5SChristoph Hellwig * be done using inode_permission(). 2898c744fb8SChristoph Hellwig */ 2908c744fb8SChristoph Hellwig int file_permission(struct file *file, int mask) 2918c744fb8SChristoph Hellwig { 292f419a2e3SAl Viro return inode_permission(file->f_path.dentry->d_inode, mask); 2938c744fb8SChristoph Hellwig } 2948c744fb8SChristoph Hellwig 2951da177e4SLinus Torvalds /* 2961da177e4SLinus Torvalds * get_write_access() gets write permission for a file. 2971da177e4SLinus Torvalds * put_write_access() releases this write permission. 2981da177e4SLinus Torvalds * This is used for regular files. 2991da177e4SLinus Torvalds * We cannot support write (and maybe mmap read-write shared) accesses and 3001da177e4SLinus Torvalds * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode 3011da177e4SLinus Torvalds * can have the following values: 3021da177e4SLinus Torvalds * 0: no writers, no VM_DENYWRITE mappings 3031da177e4SLinus Torvalds * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist 3041da177e4SLinus Torvalds * > 0: (i_writecount) users are writing to the file. 3051da177e4SLinus Torvalds * 3061da177e4SLinus Torvalds * Normally we operate on that counter with atomic_{inc,dec} and it's safe 3071da177e4SLinus Torvalds * except for the cases where we don't hold i_writecount yet. Then we need to 3081da177e4SLinus Torvalds * use {get,deny}_write_access() - these functions check the sign and refuse 3091da177e4SLinus Torvalds * to do the change if sign is wrong. Exclusion between them is provided by 3101da177e4SLinus Torvalds * the inode->i_lock spinlock. 3111da177e4SLinus Torvalds */ 3121da177e4SLinus Torvalds 3131da177e4SLinus Torvalds int get_write_access(struct inode * inode) 3141da177e4SLinus Torvalds { 3151da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3161da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) < 0) { 3171da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3181da177e4SLinus Torvalds return -ETXTBSY; 3191da177e4SLinus Torvalds } 3201da177e4SLinus Torvalds atomic_inc(&inode->i_writecount); 3211da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3221da177e4SLinus Torvalds 3231da177e4SLinus Torvalds return 0; 3241da177e4SLinus Torvalds } 3251da177e4SLinus Torvalds 3261da177e4SLinus Torvalds int deny_write_access(struct file * file) 3271da177e4SLinus Torvalds { 3280f7fc9e4SJosef "Jeff" Sipek struct inode *inode = file->f_path.dentry->d_inode; 3291da177e4SLinus Torvalds 3301da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3311da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) > 0) { 3321da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3331da177e4SLinus Torvalds return -ETXTBSY; 3341da177e4SLinus Torvalds } 3351da177e4SLinus Torvalds atomic_dec(&inode->i_writecount); 3361da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3371da177e4SLinus Torvalds 3381da177e4SLinus Torvalds return 0; 3391da177e4SLinus Torvalds } 3401da177e4SLinus Torvalds 3411d957f9bSJan Blunck /** 3425dd784d0SJan Blunck * path_get - get a reference to a path 3435dd784d0SJan Blunck * @path: path to get the reference to 3445dd784d0SJan Blunck * 3455dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 3465dd784d0SJan Blunck */ 3475dd784d0SJan Blunck void path_get(struct path *path) 3485dd784d0SJan Blunck { 3495dd784d0SJan Blunck mntget(path->mnt); 3505dd784d0SJan Blunck dget(path->dentry); 3515dd784d0SJan Blunck } 3525dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 3535dd784d0SJan Blunck 3545dd784d0SJan Blunck /** 3551d957f9bSJan Blunck * path_put - put a reference to a path 3561d957f9bSJan Blunck * @path: path to put the reference to 3571d957f9bSJan Blunck * 3581d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 3591d957f9bSJan Blunck */ 3601d957f9bSJan Blunck void path_put(struct path *path) 3611da177e4SLinus Torvalds { 3621d957f9bSJan Blunck dput(path->dentry); 3631d957f9bSJan Blunck mntput(path->mnt); 3641da177e4SLinus Torvalds } 3651d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 3661da177e4SLinus Torvalds 367834f2a4aSTrond Myklebust /** 368834f2a4aSTrond Myklebust * release_open_intent - free up open intent resources 369834f2a4aSTrond Myklebust * @nd: pointer to nameidata 370834f2a4aSTrond Myklebust */ 371834f2a4aSTrond Myklebust void release_open_intent(struct nameidata *nd) 372834f2a4aSTrond Myklebust { 3730f7fc9e4SJosef "Jeff" Sipek if (nd->intent.open.file->f_path.dentry == NULL) 374834f2a4aSTrond Myklebust put_filp(nd->intent.open.file); 375834f2a4aSTrond Myklebust else 376834f2a4aSTrond Myklebust fput(nd->intent.open.file); 377834f2a4aSTrond Myklebust } 378834f2a4aSTrond Myklebust 379bcdc5e01SIan Kent static inline struct dentry * 380bcdc5e01SIan Kent do_revalidate(struct dentry *dentry, struct nameidata *nd) 381bcdc5e01SIan Kent { 382bcdc5e01SIan Kent int status = dentry->d_op->d_revalidate(dentry, nd); 383bcdc5e01SIan Kent if (unlikely(status <= 0)) { 384bcdc5e01SIan Kent /* 385bcdc5e01SIan Kent * The dentry failed validation. 386bcdc5e01SIan Kent * If d_revalidate returned 0 attempt to invalidate 387bcdc5e01SIan Kent * the dentry otherwise d_revalidate is asking us 388bcdc5e01SIan Kent * to return a fail status. 389bcdc5e01SIan Kent */ 390bcdc5e01SIan Kent if (!status) { 391bcdc5e01SIan Kent if (!d_invalidate(dentry)) { 392bcdc5e01SIan Kent dput(dentry); 393bcdc5e01SIan Kent dentry = NULL; 394bcdc5e01SIan Kent } 395bcdc5e01SIan Kent } else { 396bcdc5e01SIan Kent dput(dentry); 397bcdc5e01SIan Kent dentry = ERR_PTR(status); 398bcdc5e01SIan Kent } 399bcdc5e01SIan Kent } 400bcdc5e01SIan Kent return dentry; 401bcdc5e01SIan Kent } 402bcdc5e01SIan Kent 4031da177e4SLinus Torvalds /* 4041da177e4SLinus Torvalds * Internal lookup() using the new generic dcache. 4051da177e4SLinus Torvalds * SMP-safe 4061da177e4SLinus Torvalds */ 4071da177e4SLinus Torvalds static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) 4081da177e4SLinus Torvalds { 4091da177e4SLinus Torvalds struct dentry * dentry = __d_lookup(parent, name); 4101da177e4SLinus Torvalds 4111da177e4SLinus Torvalds /* lockess __d_lookup may fail due to concurrent d_move() 4121da177e4SLinus Torvalds * in some unrelated directory, so try with d_lookup 4131da177e4SLinus Torvalds */ 4141da177e4SLinus Torvalds if (!dentry) 4151da177e4SLinus Torvalds dentry = d_lookup(parent, name); 4161da177e4SLinus Torvalds 417bcdc5e01SIan Kent if (dentry && dentry->d_op && dentry->d_op->d_revalidate) 418bcdc5e01SIan Kent dentry = do_revalidate(dentry, nd); 419bcdc5e01SIan Kent 4201da177e4SLinus Torvalds return dentry; 4211da177e4SLinus Torvalds } 4221da177e4SLinus Torvalds 4231da177e4SLinus Torvalds /* 4241da177e4SLinus Torvalds * Short-cut version of permission(), for calling by 4251da177e4SLinus Torvalds * path_walk(), when dcache lock is held. Combines parts 4261da177e4SLinus Torvalds * of permission() and generic_permission(), and tests ONLY for 4271da177e4SLinus Torvalds * MAY_EXEC permission. 4281da177e4SLinus Torvalds * 4291da177e4SLinus Torvalds * If appropriate, check DAC only. If not appropriate, or 4301da177e4SLinus Torvalds * short-cut DAC fails, then call permission() to do more 4311da177e4SLinus Torvalds * complete permission check. 4321da177e4SLinus Torvalds */ 433672b16b2SAl Viro static int exec_permission_lite(struct inode *inode) 4341da177e4SLinus Torvalds { 4351da177e4SLinus Torvalds umode_t mode = inode->i_mode; 4361da177e4SLinus Torvalds 437acfa4380SAl Viro if (inode->i_op->permission) 4381da177e4SLinus Torvalds return -EAGAIN; 4391da177e4SLinus Torvalds 440da9592edSDavid Howells if (current_fsuid() == inode->i_uid) 4411da177e4SLinus Torvalds mode >>= 6; 4421da177e4SLinus Torvalds else if (in_group_p(inode->i_gid)) 4431da177e4SLinus Torvalds mode >>= 3; 4441da177e4SLinus Torvalds 4451da177e4SLinus Torvalds if (mode & MAY_EXEC) 4461da177e4SLinus Torvalds goto ok; 4471da177e4SLinus Torvalds 4481da177e4SLinus Torvalds if ((inode->i_mode & S_IXUGO) && capable(CAP_DAC_OVERRIDE)) 4491da177e4SLinus Torvalds goto ok; 4501da177e4SLinus Torvalds 4511da177e4SLinus Torvalds if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_OVERRIDE)) 4521da177e4SLinus Torvalds goto ok; 4531da177e4SLinus Torvalds 4541da177e4SLinus Torvalds if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_READ_SEARCH)) 4551da177e4SLinus Torvalds goto ok; 4561da177e4SLinus Torvalds 4571da177e4SLinus Torvalds return -EACCES; 4581da177e4SLinus Torvalds ok: 459b77b0646SAl Viro return security_inode_permission(inode, MAY_EXEC); 4601da177e4SLinus Torvalds } 4611da177e4SLinus Torvalds 4621da177e4SLinus Torvalds /* 4631da177e4SLinus Torvalds * This is called when everything else fails, and we actually have 4641da177e4SLinus Torvalds * to go to the low-level filesystem to find out what we should do.. 4651da177e4SLinus Torvalds * 4661da177e4SLinus Torvalds * We get the directory semaphore, and after getting that we also 4671da177e4SLinus Torvalds * make sure that nobody added the entry to the dcache in the meantime.. 4681da177e4SLinus Torvalds * SMP-safe 4691da177e4SLinus Torvalds */ 4701da177e4SLinus Torvalds static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) 4711da177e4SLinus Torvalds { 4721da177e4SLinus Torvalds struct dentry * result; 4731da177e4SLinus Torvalds struct inode *dir = parent->d_inode; 4741da177e4SLinus Torvalds 4751b1dcc1bSJes Sorensen mutex_lock(&dir->i_mutex); 4761da177e4SLinus Torvalds /* 4771da177e4SLinus Torvalds * First re-do the cached lookup just in case it was created 4781da177e4SLinus Torvalds * while we waited for the directory semaphore.. 4791da177e4SLinus Torvalds * 4801da177e4SLinus Torvalds * FIXME! This could use version numbering or similar to 4811da177e4SLinus Torvalds * avoid unnecessary cache lookups. 4821da177e4SLinus Torvalds * 4831da177e4SLinus Torvalds * The "dcache_lock" is purely to protect the RCU list walker 4841da177e4SLinus Torvalds * from concurrent renames at this point (we mustn't get false 4851da177e4SLinus Torvalds * negatives from the RCU list walk here, unlike the optimistic 4861da177e4SLinus Torvalds * fast walk). 4871da177e4SLinus Torvalds * 4881da177e4SLinus Torvalds * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup 4891da177e4SLinus Torvalds */ 4901da177e4SLinus Torvalds result = d_lookup(parent, name); 4911da177e4SLinus Torvalds if (!result) { 492d70b67c8SMiklos Szeredi struct dentry *dentry; 493d70b67c8SMiklos Szeredi 494d70b67c8SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 495d70b67c8SMiklos Szeredi result = ERR_PTR(-ENOENT); 496d70b67c8SMiklos Szeredi if (IS_DEADDIR(dir)) 497d70b67c8SMiklos Szeredi goto out_unlock; 498d70b67c8SMiklos Szeredi 499d70b67c8SMiklos Szeredi dentry = d_alloc(parent, name); 5001da177e4SLinus Torvalds result = ERR_PTR(-ENOMEM); 5011da177e4SLinus Torvalds if (dentry) { 5021da177e4SLinus Torvalds result = dir->i_op->lookup(dir, dentry, nd); 5031da177e4SLinus Torvalds if (result) 5041da177e4SLinus Torvalds dput(dentry); 5051da177e4SLinus Torvalds else 5061da177e4SLinus Torvalds result = dentry; 5071da177e4SLinus Torvalds } 508d70b67c8SMiklos Szeredi out_unlock: 5091b1dcc1bSJes Sorensen mutex_unlock(&dir->i_mutex); 5101da177e4SLinus Torvalds return result; 5111da177e4SLinus Torvalds } 5121da177e4SLinus Torvalds 5131da177e4SLinus Torvalds /* 5141da177e4SLinus Torvalds * Uhhuh! Nasty case: the cache was re-populated while 5151da177e4SLinus Torvalds * we waited on the semaphore. Need to revalidate. 5161da177e4SLinus Torvalds */ 5171b1dcc1bSJes Sorensen mutex_unlock(&dir->i_mutex); 5181da177e4SLinus Torvalds if (result->d_op && result->d_op->d_revalidate) { 519bcdc5e01SIan Kent result = do_revalidate(result, nd); 520bcdc5e01SIan Kent if (!result) 5211da177e4SLinus Torvalds result = ERR_PTR(-ENOENT); 5221da177e4SLinus Torvalds } 5231da177e4SLinus Torvalds return result; 5241da177e4SLinus Torvalds } 5251da177e4SLinus Torvalds 526a02f76c3SAl Viro /* 527a02f76c3SAl Viro * Wrapper to retry pathname resolution whenever the underlying 528a02f76c3SAl Viro * file system returns an ESTALE. 529a02f76c3SAl Viro * 530a02f76c3SAl Viro * Retry the whole path once, forcing real lookup requests 531a02f76c3SAl Viro * instead of relying on the dcache. 532a02f76c3SAl Viro */ 533a02f76c3SAl Viro static __always_inline int link_path_walk(const char *name, struct nameidata *nd) 534a02f76c3SAl Viro { 535a02f76c3SAl Viro struct path save = nd->path; 536a02f76c3SAl Viro int result; 537a02f76c3SAl Viro 538a02f76c3SAl Viro /* make sure the stuff we saved doesn't go away */ 539c8e7f449SJan Blunck path_get(&save); 540a02f76c3SAl Viro 541a02f76c3SAl Viro result = __link_path_walk(name, nd); 542a02f76c3SAl Viro if (result == -ESTALE) { 543a02f76c3SAl Viro /* nd->path had been dropped */ 544a02f76c3SAl Viro nd->path = save; 545c8e7f449SJan Blunck path_get(&nd->path); 546a02f76c3SAl Viro nd->flags |= LOOKUP_REVAL; 547a02f76c3SAl Viro result = __link_path_walk(name, nd); 548a02f76c3SAl Viro } 549a02f76c3SAl Viro 550a02f76c3SAl Viro path_put(&save); 551a02f76c3SAl Viro 552a02f76c3SAl Viro return result; 553a02f76c3SAl Viro } 554a02f76c3SAl Viro 5552a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 5562a737871SAl Viro { 5572a737871SAl Viro if (!nd->root.mnt) { 5582a737871SAl Viro struct fs_struct *fs = current->fs; 5592a737871SAl Viro read_lock(&fs->lock); 5602a737871SAl Viro nd->root = fs->root; 5612a737871SAl Viro path_get(&nd->root); 5622a737871SAl Viro read_unlock(&fs->lock); 5632a737871SAl Viro } 5642a737871SAl Viro } 5652a737871SAl Viro 566f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 5671da177e4SLinus Torvalds { 5681da177e4SLinus Torvalds int res = 0; 5691da177e4SLinus Torvalds char *name; 5701da177e4SLinus Torvalds if (IS_ERR(link)) 5711da177e4SLinus Torvalds goto fail; 5721da177e4SLinus Torvalds 5731da177e4SLinus Torvalds if (*link == '/') { 5742a737871SAl Viro set_root(nd); 5751d957f9bSJan Blunck path_put(&nd->path); 5762a737871SAl Viro nd->path = nd->root; 5772a737871SAl Viro path_get(&nd->root); 5781da177e4SLinus Torvalds } 579b4091d5fSChristoph Hellwig 5801da177e4SLinus Torvalds res = link_path_walk(link, nd); 5811da177e4SLinus Torvalds if (nd->depth || res || nd->last_type!=LAST_NORM) 5821da177e4SLinus Torvalds return res; 5831da177e4SLinus Torvalds /* 5841da177e4SLinus Torvalds * If it is an iterative symlinks resolution in open_namei() we 5851da177e4SLinus Torvalds * have to copy the last component. And all that crap because of 5861da177e4SLinus Torvalds * bloody create() on broken symlinks. Furrfu... 5871da177e4SLinus Torvalds */ 5881da177e4SLinus Torvalds name = __getname(); 5891da177e4SLinus Torvalds if (unlikely(!name)) { 5901d957f9bSJan Blunck path_put(&nd->path); 5911da177e4SLinus Torvalds return -ENOMEM; 5921da177e4SLinus Torvalds } 5931da177e4SLinus Torvalds strcpy(name, nd->last.name); 5941da177e4SLinus Torvalds nd->last.name = name; 5951da177e4SLinus Torvalds return 0; 5961da177e4SLinus Torvalds fail: 5971d957f9bSJan Blunck path_put(&nd->path); 5981da177e4SLinus Torvalds return PTR_ERR(link); 5991da177e4SLinus Torvalds } 6001da177e4SLinus Torvalds 6011d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 602051d3812SIan Kent { 603051d3812SIan Kent dput(path->dentry); 6044ac91378SJan Blunck if (path->mnt != nd->path.mnt) 605051d3812SIan Kent mntput(path->mnt); 606051d3812SIan Kent } 607051d3812SIan Kent 608051d3812SIan Kent static inline void path_to_nameidata(struct path *path, struct nameidata *nd) 609051d3812SIan Kent { 6104ac91378SJan Blunck dput(nd->path.dentry); 6114ac91378SJan Blunck if (nd->path.mnt != path->mnt) 6124ac91378SJan Blunck mntput(nd->path.mnt); 6134ac91378SJan Blunck nd->path.mnt = path->mnt; 6144ac91378SJan Blunck nd->path.dentry = path->dentry; 615051d3812SIan Kent } 616051d3812SIan Kent 617f1662356SArjan van de Ven static __always_inline int __do_follow_link(struct path *path, struct nameidata *nd) 6181da177e4SLinus Torvalds { 6191da177e4SLinus Torvalds int error; 620cc314eefSLinus Torvalds void *cookie; 621cd4e91d3SAl Viro struct dentry *dentry = path->dentry; 6221da177e4SLinus Torvalds 623d671a1cbSAl Viro touch_atime(path->mnt, dentry); 6241da177e4SLinus Torvalds nd_set_link(nd, NULL); 625cd4e91d3SAl Viro 6264ac91378SJan Blunck if (path->mnt != nd->path.mnt) { 627051d3812SIan Kent path_to_nameidata(path, nd); 628051d3812SIan Kent dget(dentry); 629051d3812SIan Kent } 630cd4e91d3SAl Viro mntget(path->mnt); 631cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, nd); 632cc314eefSLinus Torvalds error = PTR_ERR(cookie); 633cc314eefSLinus Torvalds if (!IS_ERR(cookie)) { 6341da177e4SLinus Torvalds char *s = nd_get_link(nd); 635cc314eefSLinus Torvalds error = 0; 6361da177e4SLinus Torvalds if (s) 6371da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 6381da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 639cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, nd, cookie); 6401da177e4SLinus Torvalds } 64109da5916SJan Blunck path_put(path); 6421da177e4SLinus Torvalds 6431da177e4SLinus Torvalds return error; 6441da177e4SLinus Torvalds } 6451da177e4SLinus Torvalds 6461da177e4SLinus Torvalds /* 6471da177e4SLinus Torvalds * This limits recursive symlink follows to 8, while 6481da177e4SLinus Torvalds * limiting consecutive symlinks to 40. 6491da177e4SLinus Torvalds * 6501da177e4SLinus Torvalds * Without that kind of total limit, nasty chains of consecutive 6511da177e4SLinus Torvalds * symlinks can cause almost arbitrarily long lookups. 6521da177e4SLinus Torvalds */ 65390ebe565SAl Viro static inline int do_follow_link(struct path *path, struct nameidata *nd) 6541da177e4SLinus Torvalds { 6551da177e4SLinus Torvalds int err = -ELOOP; 6561da177e4SLinus Torvalds if (current->link_count >= MAX_NESTED_LINKS) 6571da177e4SLinus Torvalds goto loop; 6581da177e4SLinus Torvalds if (current->total_link_count >= 40) 6591da177e4SLinus Torvalds goto loop; 6601da177e4SLinus Torvalds BUG_ON(nd->depth >= MAX_NESTED_LINKS); 6611da177e4SLinus Torvalds cond_resched(); 66290ebe565SAl Viro err = security_inode_follow_link(path->dentry, nd); 6631da177e4SLinus Torvalds if (err) 6641da177e4SLinus Torvalds goto loop; 6651da177e4SLinus Torvalds current->link_count++; 6661da177e4SLinus Torvalds current->total_link_count++; 6671da177e4SLinus Torvalds nd->depth++; 668cd4e91d3SAl Viro err = __do_follow_link(path, nd); 6691da177e4SLinus Torvalds current->link_count--; 6701da177e4SLinus Torvalds nd->depth--; 6711da177e4SLinus Torvalds return err; 6721da177e4SLinus Torvalds loop: 6731d957f9bSJan Blunck path_put_conditional(path, nd); 6741d957f9bSJan Blunck path_put(&nd->path); 6751da177e4SLinus Torvalds return err; 6761da177e4SLinus Torvalds } 6771da177e4SLinus Torvalds 678bab77ebfSAl Viro int follow_up(struct path *path) 6791da177e4SLinus Torvalds { 6801da177e4SLinus Torvalds struct vfsmount *parent; 6811da177e4SLinus Torvalds struct dentry *mountpoint; 6821da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 683bab77ebfSAl Viro parent = path->mnt->mnt_parent; 684bab77ebfSAl Viro if (parent == path->mnt) { 6851da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 6861da177e4SLinus Torvalds return 0; 6871da177e4SLinus Torvalds } 6881da177e4SLinus Torvalds mntget(parent); 689bab77ebfSAl Viro mountpoint = dget(path->mnt->mnt_mountpoint); 6901da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 691bab77ebfSAl Viro dput(path->dentry); 692bab77ebfSAl Viro path->dentry = mountpoint; 693bab77ebfSAl Viro mntput(path->mnt); 694bab77ebfSAl Viro path->mnt = parent; 6951da177e4SLinus Torvalds return 1; 6961da177e4SLinus Torvalds } 6971da177e4SLinus Torvalds 6981da177e4SLinus Torvalds /* no need for dcache_lock, as serialization is taken care in 6991da177e4SLinus Torvalds * namespace.c 7001da177e4SLinus Torvalds */ 701463ffb2eSAl Viro static int __follow_mount(struct path *path) 702463ffb2eSAl Viro { 703463ffb2eSAl Viro int res = 0; 704463ffb2eSAl Viro while (d_mountpoint(path->dentry)) { 705463ffb2eSAl Viro struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry); 706463ffb2eSAl Viro if (!mounted) 707463ffb2eSAl Viro break; 708463ffb2eSAl Viro dput(path->dentry); 709463ffb2eSAl Viro if (res) 710463ffb2eSAl Viro mntput(path->mnt); 711463ffb2eSAl Viro path->mnt = mounted; 712463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 713463ffb2eSAl Viro res = 1; 714463ffb2eSAl Viro } 715463ffb2eSAl Viro return res; 716463ffb2eSAl Viro } 717463ffb2eSAl Viro 71858c465ebSAl Viro static void follow_mount(struct vfsmount **mnt, struct dentry **dentry) 7191da177e4SLinus Torvalds { 7201da177e4SLinus Torvalds while (d_mountpoint(*dentry)) { 7211da177e4SLinus Torvalds struct vfsmount *mounted = lookup_mnt(*mnt, *dentry); 7221da177e4SLinus Torvalds if (!mounted) 7231da177e4SLinus Torvalds break; 72458c465ebSAl Viro dput(*dentry); 7251da177e4SLinus Torvalds mntput(*mnt); 7261da177e4SLinus Torvalds *mnt = mounted; 7271da177e4SLinus Torvalds *dentry = dget(mounted->mnt_root); 7281da177e4SLinus Torvalds } 7291da177e4SLinus Torvalds } 7301da177e4SLinus Torvalds 7311da177e4SLinus Torvalds /* no need for dcache_lock, as serialization is taken care in 7321da177e4SLinus Torvalds * namespace.c 7331da177e4SLinus Torvalds */ 734e13b210fSAl Viro int follow_down(struct vfsmount **mnt, struct dentry **dentry) 7351da177e4SLinus Torvalds { 7361da177e4SLinus Torvalds struct vfsmount *mounted; 7371da177e4SLinus Torvalds 7381da177e4SLinus Torvalds mounted = lookup_mnt(*mnt, *dentry); 7391da177e4SLinus Torvalds if (mounted) { 740e13b210fSAl Viro dput(*dentry); 7411da177e4SLinus Torvalds mntput(*mnt); 7421da177e4SLinus Torvalds *mnt = mounted; 7431da177e4SLinus Torvalds *dentry = dget(mounted->mnt_root); 7441da177e4SLinus Torvalds return 1; 7451da177e4SLinus Torvalds } 7461da177e4SLinus Torvalds return 0; 7471da177e4SLinus Torvalds } 7481da177e4SLinus Torvalds 749f1662356SArjan van de Ven static __always_inline void follow_dotdot(struct nameidata *nd) 7501da177e4SLinus Torvalds { 7512a737871SAl Viro set_root(nd); 752e518ddb7SAndreas Mohr 7531da177e4SLinus Torvalds while(1) { 7541da177e4SLinus Torvalds struct vfsmount *parent; 7554ac91378SJan Blunck struct dentry *old = nd->path.dentry; 7561da177e4SLinus Torvalds 7572a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 7582a737871SAl Viro nd->path.mnt == nd->root.mnt) { 7591da177e4SLinus Torvalds break; 7601da177e4SLinus Torvalds } 7611da177e4SLinus Torvalds spin_lock(&dcache_lock); 7624ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 7634ac91378SJan Blunck nd->path.dentry = dget(nd->path.dentry->d_parent); 7641da177e4SLinus Torvalds spin_unlock(&dcache_lock); 7651da177e4SLinus Torvalds dput(old); 7661da177e4SLinus Torvalds break; 7671da177e4SLinus Torvalds } 7681da177e4SLinus Torvalds spin_unlock(&dcache_lock); 7691da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 7704ac91378SJan Blunck parent = nd->path.mnt->mnt_parent; 7714ac91378SJan Blunck if (parent == nd->path.mnt) { 7721da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7731da177e4SLinus Torvalds break; 7741da177e4SLinus Torvalds } 7751da177e4SLinus Torvalds mntget(parent); 7764ac91378SJan Blunck nd->path.dentry = dget(nd->path.mnt->mnt_mountpoint); 7771da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7781da177e4SLinus Torvalds dput(old); 7794ac91378SJan Blunck mntput(nd->path.mnt); 7804ac91378SJan Blunck nd->path.mnt = parent; 7811da177e4SLinus Torvalds } 7824ac91378SJan Blunck follow_mount(&nd->path.mnt, &nd->path.dentry); 7831da177e4SLinus Torvalds } 7841da177e4SLinus Torvalds 7851da177e4SLinus Torvalds /* 7861da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 7871da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 7881da177e4SLinus Torvalds * It _is_ time-critical. 7891da177e4SLinus Torvalds */ 7901da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 7911da177e4SLinus Torvalds struct path *path) 7921da177e4SLinus Torvalds { 7934ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 7944ac91378SJan Blunck struct dentry *dentry = __d_lookup(nd->path.dentry, name); 7951da177e4SLinus Torvalds 7961da177e4SLinus Torvalds if (!dentry) 7971da177e4SLinus Torvalds goto need_lookup; 7981da177e4SLinus Torvalds if (dentry->d_op && dentry->d_op->d_revalidate) 7991da177e4SLinus Torvalds goto need_revalidate; 8001da177e4SLinus Torvalds done: 8011da177e4SLinus Torvalds path->mnt = mnt; 8021da177e4SLinus Torvalds path->dentry = dentry; 803634ee701SAl Viro __follow_mount(path); 8041da177e4SLinus Torvalds return 0; 8051da177e4SLinus Torvalds 8061da177e4SLinus Torvalds need_lookup: 8074ac91378SJan Blunck dentry = real_lookup(nd->path.dentry, name, nd); 8081da177e4SLinus Torvalds if (IS_ERR(dentry)) 8091da177e4SLinus Torvalds goto fail; 8101da177e4SLinus Torvalds goto done; 8111da177e4SLinus Torvalds 8121da177e4SLinus Torvalds need_revalidate: 813bcdc5e01SIan Kent dentry = do_revalidate(dentry, nd); 814bcdc5e01SIan Kent if (!dentry) 8151da177e4SLinus Torvalds goto need_lookup; 816bcdc5e01SIan Kent if (IS_ERR(dentry)) 817bcdc5e01SIan Kent goto fail; 818bcdc5e01SIan Kent goto done; 8191da177e4SLinus Torvalds 8201da177e4SLinus Torvalds fail: 8211da177e4SLinus Torvalds return PTR_ERR(dentry); 8221da177e4SLinus Torvalds } 8231da177e4SLinus Torvalds 8241da177e4SLinus Torvalds /* 8251da177e4SLinus Torvalds * Name resolution. 826ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 827ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 8281da177e4SLinus Torvalds * 829ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 830ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 8311da177e4SLinus Torvalds */ 832fc9b52cdSHarvey Harrison static int __link_path_walk(const char *name, struct nameidata *nd) 8331da177e4SLinus Torvalds { 8341da177e4SLinus Torvalds struct path next; 8351da177e4SLinus Torvalds struct inode *inode; 8361da177e4SLinus Torvalds int err; 8371da177e4SLinus Torvalds unsigned int lookup_flags = nd->flags; 8381da177e4SLinus Torvalds 8391da177e4SLinus Torvalds while (*name=='/') 8401da177e4SLinus Torvalds name++; 8411da177e4SLinus Torvalds if (!*name) 8421da177e4SLinus Torvalds goto return_reval; 8431da177e4SLinus Torvalds 8444ac91378SJan Blunck inode = nd->path.dentry->d_inode; 8451da177e4SLinus Torvalds if (nd->depth) 846f55eab82STrond Myklebust lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE); 8471da177e4SLinus Torvalds 8481da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 8491da177e4SLinus Torvalds for(;;) { 8501da177e4SLinus Torvalds unsigned long hash; 8511da177e4SLinus Torvalds struct qstr this; 8521da177e4SLinus Torvalds unsigned int c; 8531da177e4SLinus Torvalds 854cdce5d6bSTrond Myklebust nd->flags |= LOOKUP_CONTINUE; 855672b16b2SAl Viro err = exec_permission_lite(inode); 856e4543eddSChristoph Hellwig if (err == -EAGAIN) 857cb23beb5SChristoph Hellwig err = inode_permission(nd->path.dentry->d_inode, 858cb23beb5SChristoph Hellwig MAY_EXEC); 8596146f0d5SMimi Zohar if (!err) 860b9fc745dSMimi Zohar err = ima_path_check(&nd->path, MAY_EXEC, 861b9fc745dSMimi Zohar IMA_COUNT_UPDATE); 8621da177e4SLinus Torvalds if (err) 8631da177e4SLinus Torvalds break; 8641da177e4SLinus Torvalds 8651da177e4SLinus Torvalds this.name = name; 8661da177e4SLinus Torvalds c = *(const unsigned char *)name; 8671da177e4SLinus Torvalds 8681da177e4SLinus Torvalds hash = init_name_hash(); 8691da177e4SLinus Torvalds do { 8701da177e4SLinus Torvalds name++; 8711da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 8721da177e4SLinus Torvalds c = *(const unsigned char *)name; 8731da177e4SLinus Torvalds } while (c && (c != '/')); 8741da177e4SLinus Torvalds this.len = name - (const char *) this.name; 8751da177e4SLinus Torvalds this.hash = end_name_hash(hash); 8761da177e4SLinus Torvalds 8771da177e4SLinus Torvalds /* remove trailing slashes? */ 8781da177e4SLinus Torvalds if (!c) 8791da177e4SLinus Torvalds goto last_component; 8801da177e4SLinus Torvalds while (*++name == '/'); 8811da177e4SLinus Torvalds if (!*name) 8821da177e4SLinus Torvalds goto last_with_slashes; 8831da177e4SLinus Torvalds 8841da177e4SLinus Torvalds /* 8851da177e4SLinus Torvalds * "." and ".." are special - ".." especially so because it has 8861da177e4SLinus Torvalds * to be able to know about the current root directory and 8871da177e4SLinus Torvalds * parent relationships. 8881da177e4SLinus Torvalds */ 8891da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 8901da177e4SLinus Torvalds default: 8911da177e4SLinus Torvalds break; 8921da177e4SLinus Torvalds case 2: 8931da177e4SLinus Torvalds if (this.name[1] != '.') 8941da177e4SLinus Torvalds break; 89558c465ebSAl Viro follow_dotdot(nd); 8964ac91378SJan Blunck inode = nd->path.dentry->d_inode; 8971da177e4SLinus Torvalds /* fallthrough */ 8981da177e4SLinus Torvalds case 1: 8991da177e4SLinus Torvalds continue; 9001da177e4SLinus Torvalds } 9011da177e4SLinus Torvalds /* 9021da177e4SLinus Torvalds * See if the low-level filesystem might want 9031da177e4SLinus Torvalds * to use its own hash.. 9041da177e4SLinus Torvalds */ 9054ac91378SJan Blunck if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { 9064ac91378SJan Blunck err = nd->path.dentry->d_op->d_hash(nd->path.dentry, 9074ac91378SJan Blunck &this); 9081da177e4SLinus Torvalds if (err < 0) 9091da177e4SLinus Torvalds break; 9101da177e4SLinus Torvalds } 9111da177e4SLinus Torvalds /* This does the actual lookups.. */ 9121da177e4SLinus Torvalds err = do_lookup(nd, &this, &next); 9131da177e4SLinus Torvalds if (err) 9141da177e4SLinus Torvalds break; 9151da177e4SLinus Torvalds 9161da177e4SLinus Torvalds err = -ENOENT; 9171da177e4SLinus Torvalds inode = next.dentry->d_inode; 9181da177e4SLinus Torvalds if (!inode) 9191da177e4SLinus Torvalds goto out_dput; 9201da177e4SLinus Torvalds 9211da177e4SLinus Torvalds if (inode->i_op->follow_link) { 92290ebe565SAl Viro err = do_follow_link(&next, nd); 9231da177e4SLinus Torvalds if (err) 9241da177e4SLinus Torvalds goto return_err; 9251da177e4SLinus Torvalds err = -ENOENT; 9264ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9271da177e4SLinus Torvalds if (!inode) 9281da177e4SLinus Torvalds break; 92909dd17d3SMiklos Szeredi } else 93009dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 9311da177e4SLinus Torvalds err = -ENOTDIR; 9321da177e4SLinus Torvalds if (!inode->i_op->lookup) 9331da177e4SLinus Torvalds break; 9341da177e4SLinus Torvalds continue; 9351da177e4SLinus Torvalds /* here ends the main loop */ 9361da177e4SLinus Torvalds 9371da177e4SLinus Torvalds last_with_slashes: 9381da177e4SLinus Torvalds lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 9391da177e4SLinus Torvalds last_component: 940f55eab82STrond Myklebust /* Clear LOOKUP_CONTINUE iff it was previously unset */ 941f55eab82STrond Myklebust nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; 9421da177e4SLinus Torvalds if (lookup_flags & LOOKUP_PARENT) 9431da177e4SLinus Torvalds goto lookup_parent; 9441da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 9451da177e4SLinus Torvalds default: 9461da177e4SLinus Torvalds break; 9471da177e4SLinus Torvalds case 2: 9481da177e4SLinus Torvalds if (this.name[1] != '.') 9491da177e4SLinus Torvalds break; 95058c465ebSAl Viro follow_dotdot(nd); 9514ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9521da177e4SLinus Torvalds /* fallthrough */ 9531da177e4SLinus Torvalds case 1: 9541da177e4SLinus Torvalds goto return_reval; 9551da177e4SLinus Torvalds } 9564ac91378SJan Blunck if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { 9574ac91378SJan Blunck err = nd->path.dentry->d_op->d_hash(nd->path.dentry, 9584ac91378SJan Blunck &this); 9591da177e4SLinus Torvalds if (err < 0) 9601da177e4SLinus Torvalds break; 9611da177e4SLinus Torvalds } 9621da177e4SLinus Torvalds err = do_lookup(nd, &this, &next); 9631da177e4SLinus Torvalds if (err) 9641da177e4SLinus Torvalds break; 9651da177e4SLinus Torvalds inode = next.dentry->d_inode; 9661da177e4SLinus Torvalds if ((lookup_flags & LOOKUP_FOLLOW) 967acfa4380SAl Viro && inode && inode->i_op->follow_link) { 96890ebe565SAl Viro err = do_follow_link(&next, nd); 9691da177e4SLinus Torvalds if (err) 9701da177e4SLinus Torvalds goto return_err; 9714ac91378SJan Blunck inode = nd->path.dentry->d_inode; 97209dd17d3SMiklos Szeredi } else 97309dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 9741da177e4SLinus Torvalds err = -ENOENT; 9751da177e4SLinus Torvalds if (!inode) 9761da177e4SLinus Torvalds break; 9771da177e4SLinus Torvalds if (lookup_flags & LOOKUP_DIRECTORY) { 9781da177e4SLinus Torvalds err = -ENOTDIR; 979acfa4380SAl Viro if (!inode->i_op->lookup) 9801da177e4SLinus Torvalds break; 9811da177e4SLinus Torvalds } 9821da177e4SLinus Torvalds goto return_base; 9831da177e4SLinus Torvalds lookup_parent: 9841da177e4SLinus Torvalds nd->last = this; 9851da177e4SLinus Torvalds nd->last_type = LAST_NORM; 9861da177e4SLinus Torvalds if (this.name[0] != '.') 9871da177e4SLinus Torvalds goto return_base; 9881da177e4SLinus Torvalds if (this.len == 1) 9891da177e4SLinus Torvalds nd->last_type = LAST_DOT; 9901da177e4SLinus Torvalds else if (this.len == 2 && this.name[1] == '.') 9911da177e4SLinus Torvalds nd->last_type = LAST_DOTDOT; 9921da177e4SLinus Torvalds else 9931da177e4SLinus Torvalds goto return_base; 9941da177e4SLinus Torvalds return_reval: 9951da177e4SLinus Torvalds /* 9961da177e4SLinus Torvalds * We bypassed the ordinary revalidation routines. 9971da177e4SLinus Torvalds * We may need to check the cached dentry for staleness. 9981da177e4SLinus Torvalds */ 9994ac91378SJan Blunck if (nd->path.dentry && nd->path.dentry->d_sb && 10004ac91378SJan Blunck (nd->path.dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) { 10011da177e4SLinus Torvalds err = -ESTALE; 10021da177e4SLinus Torvalds /* Note: we do not d_invalidate() */ 10034ac91378SJan Blunck if (!nd->path.dentry->d_op->d_revalidate( 10044ac91378SJan Blunck nd->path.dentry, nd)) 10051da177e4SLinus Torvalds break; 10061da177e4SLinus Torvalds } 10071da177e4SLinus Torvalds return_base: 10081da177e4SLinus Torvalds return 0; 10091da177e4SLinus Torvalds out_dput: 10101d957f9bSJan Blunck path_put_conditional(&next, nd); 10111da177e4SLinus Torvalds break; 10121da177e4SLinus Torvalds } 10131d957f9bSJan Blunck path_put(&nd->path); 10141da177e4SLinus Torvalds return_err: 10151da177e4SLinus Torvalds return err; 10161da177e4SLinus Torvalds } 10171da177e4SLinus Torvalds 1018fc9b52cdSHarvey Harrison static int path_walk(const char *name, struct nameidata *nd) 10191da177e4SLinus Torvalds { 10201da177e4SLinus Torvalds current->total_link_count = 0; 10211da177e4SLinus Torvalds return link_path_walk(name, nd); 10221da177e4SLinus Torvalds } 10231da177e4SLinus Torvalds 10249b4a9b14SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, struct nameidata *nd) 10251da177e4SLinus Torvalds { 1026ea3834d9SPrasanna Meda int retval = 0; 1027170aa3d0SUlrich Drepper int fput_needed; 1028170aa3d0SUlrich Drepper struct file *file; 10291da177e4SLinus Torvalds 10301da177e4SLinus Torvalds nd->last_type = LAST_ROOT; /* if there are only slashes... */ 10311da177e4SLinus Torvalds nd->flags = flags; 10321da177e4SLinus Torvalds nd->depth = 0; 10332a737871SAl Viro nd->root.mnt = NULL; 10341da177e4SLinus Torvalds 10351da177e4SLinus Torvalds if (*name=='/') { 10362a737871SAl Viro set_root(nd); 10372a737871SAl Viro nd->path = nd->root; 10382a737871SAl Viro path_get(&nd->root); 10395590ff0dSUlrich Drepper } else if (dfd == AT_FDCWD) { 10402a737871SAl Viro struct fs_struct *fs = current->fs; 1041e518ddb7SAndreas Mohr read_lock(&fs->lock); 10426ac08c39SJan Blunck nd->path = fs->pwd; 10436ac08c39SJan Blunck path_get(&fs->pwd); 1044e518ddb7SAndreas Mohr read_unlock(&fs->lock); 10455590ff0dSUlrich Drepper } else { 10465590ff0dSUlrich Drepper struct dentry *dentry; 10475590ff0dSUlrich Drepper 10485590ff0dSUlrich Drepper file = fget_light(dfd, &fput_needed); 10495590ff0dSUlrich Drepper retval = -EBADF; 1050170aa3d0SUlrich Drepper if (!file) 10516d09bb62STrond Myklebust goto out_fail; 10525590ff0dSUlrich Drepper 10530f7fc9e4SJosef "Jeff" Sipek dentry = file->f_path.dentry; 10545590ff0dSUlrich Drepper 10555590ff0dSUlrich Drepper retval = -ENOTDIR; 1056170aa3d0SUlrich Drepper if (!S_ISDIR(dentry->d_inode->i_mode)) 10576d09bb62STrond Myklebust goto fput_fail; 10585590ff0dSUlrich Drepper 10595590ff0dSUlrich Drepper retval = file_permission(file, MAY_EXEC); 1060170aa3d0SUlrich Drepper if (retval) 10616d09bb62STrond Myklebust goto fput_fail; 10625590ff0dSUlrich Drepper 10635dd784d0SJan Blunck nd->path = file->f_path; 10645dd784d0SJan Blunck path_get(&file->f_path); 10655590ff0dSUlrich Drepper 10665590ff0dSUlrich Drepper fput_light(file, fput_needed); 10671da177e4SLinus Torvalds } 10689b4a9b14SAl Viro return 0; 10692dfdd266SJosef 'Jeff' Sipek 10709b4a9b14SAl Viro fput_fail: 10719b4a9b14SAl Viro fput_light(file, fput_needed); 10729b4a9b14SAl Viro out_fail: 10739b4a9b14SAl Viro return retval; 10749b4a9b14SAl Viro } 10759b4a9b14SAl Viro 10769b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 10779b4a9b14SAl Viro static int do_path_lookup(int dfd, const char *name, 10789b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 10799b4a9b14SAl Viro { 10809b4a9b14SAl Viro int retval = path_init(dfd, name, flags, nd); 10819b4a9b14SAl Viro if (!retval) 10822dfdd266SJosef 'Jeff' Sipek retval = path_walk(name, nd); 10834ac91378SJan Blunck if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && 10844ac91378SJan Blunck nd->path.dentry->d_inode)) 10854ac91378SJan Blunck audit_inode(name, nd->path.dentry); 10862a737871SAl Viro if (nd->root.mnt) { 10872a737871SAl Viro path_put(&nd->root); 10882a737871SAl Viro nd->root.mnt = NULL; 10892a737871SAl Viro } 1090170aa3d0SUlrich Drepper return retval; 10911da177e4SLinus Torvalds } 10921da177e4SLinus Torvalds 1093fc9b52cdSHarvey Harrison int path_lookup(const char *name, unsigned int flags, 10945590ff0dSUlrich Drepper struct nameidata *nd) 10955590ff0dSUlrich Drepper { 10965590ff0dSUlrich Drepper return do_path_lookup(AT_FDCWD, name, flags, nd); 10975590ff0dSUlrich Drepper } 10985590ff0dSUlrich Drepper 1099d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 1100d1811465SAl Viro { 1101d1811465SAl Viro struct nameidata nd; 1102d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 1103d1811465SAl Viro if (!res) 1104d1811465SAl Viro *path = nd.path; 1105d1811465SAl Viro return res; 1106d1811465SAl Viro } 1107d1811465SAl Viro 110816f18200SJosef 'Jeff' Sipek /** 110916f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 111016f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 111116f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 111216f18200SJosef 'Jeff' Sipek * @name: pointer to file name 111316f18200SJosef 'Jeff' Sipek * @flags: lookup flags 111416f18200SJosef 'Jeff' Sipek * @nd: pointer to nameidata 111516f18200SJosef 'Jeff' Sipek */ 111616f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 111716f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 111816f18200SJosef 'Jeff' Sipek struct nameidata *nd) 111916f18200SJosef 'Jeff' Sipek { 112016f18200SJosef 'Jeff' Sipek int retval; 112116f18200SJosef 'Jeff' Sipek 112216f18200SJosef 'Jeff' Sipek /* same as do_path_lookup */ 112316f18200SJosef 'Jeff' Sipek nd->last_type = LAST_ROOT; 112416f18200SJosef 'Jeff' Sipek nd->flags = flags; 112516f18200SJosef 'Jeff' Sipek nd->depth = 0; 112616f18200SJosef 'Jeff' Sipek 1127c8e7f449SJan Blunck nd->path.dentry = dentry; 1128c8e7f449SJan Blunck nd->path.mnt = mnt; 1129c8e7f449SJan Blunck path_get(&nd->path); 11305b857119SAl Viro nd->root = nd->path; 11315b857119SAl Viro path_get(&nd->root); 113216f18200SJosef 'Jeff' Sipek 113316f18200SJosef 'Jeff' Sipek retval = path_walk(name, nd); 11344ac91378SJan Blunck if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && 11354ac91378SJan Blunck nd->path.dentry->d_inode)) 11364ac91378SJan Blunck audit_inode(name, nd->path.dentry); 113716f18200SJosef 'Jeff' Sipek 11382a737871SAl Viro path_put(&nd->root); 11392a737871SAl Viro nd->root.mnt = NULL; 114016f18200SJosef 'Jeff' Sipek 11412a737871SAl Viro return retval; 114216f18200SJosef 'Jeff' Sipek } 114316f18200SJosef 'Jeff' Sipek 1144834f2a4aSTrond Myklebust /** 1145834f2a4aSTrond Myklebust * path_lookup_open - lookup a file path with open intent 11467045f37bSMartin Waitz * @dfd: the directory to use as base, or AT_FDCWD 1147834f2a4aSTrond Myklebust * @name: pointer to file name 1148834f2a4aSTrond Myklebust * @lookup_flags: lookup intent flags 1149834f2a4aSTrond Myklebust * @nd: pointer to nameidata 1150834f2a4aSTrond Myklebust * @open_flags: open intent flags 1151834f2a4aSTrond Myklebust */ 11526e8341a1SAl Viro static int path_lookup_open(int dfd, const char *name, 11536e8341a1SAl Viro unsigned int lookup_flags, struct nameidata *nd, int open_flags) 1154834f2a4aSTrond Myklebust { 11558737f3a1SAl Viro struct file *filp = get_empty_filp(); 11568737f3a1SAl Viro int err; 1157834f2a4aSTrond Myklebust 11588737f3a1SAl Viro if (filp == NULL) 11598737f3a1SAl Viro return -ENFILE; 11608737f3a1SAl Viro nd->intent.open.file = filp; 11618737f3a1SAl Viro nd->intent.open.flags = open_flags; 11628737f3a1SAl Viro nd->intent.open.create_mode = 0; 11638737f3a1SAl Viro err = do_path_lookup(dfd, name, lookup_flags|LOOKUP_OPEN, nd); 11648737f3a1SAl Viro if (IS_ERR(nd->intent.open.file)) { 11658737f3a1SAl Viro if (err == 0) { 11668737f3a1SAl Viro err = PTR_ERR(nd->intent.open.file); 11678737f3a1SAl Viro path_put(&nd->path); 11688737f3a1SAl Viro } 11698737f3a1SAl Viro } else if (err != 0) 11708737f3a1SAl Viro release_open_intent(nd); 11718737f3a1SAl Viro return err; 1172834f2a4aSTrond Myklebust } 1173834f2a4aSTrond Myklebust 1174eead1911SChristoph Hellwig static struct dentry *__lookup_hash(struct qstr *name, 1175eead1911SChristoph Hellwig struct dentry *base, struct nameidata *nd) 11761da177e4SLinus Torvalds { 11771da177e4SLinus Torvalds struct dentry *dentry; 11781da177e4SLinus Torvalds struct inode *inode; 11791da177e4SLinus Torvalds int err; 11801da177e4SLinus Torvalds 11811da177e4SLinus Torvalds inode = base->d_inode; 11821da177e4SLinus Torvalds 11831da177e4SLinus Torvalds /* 11841da177e4SLinus Torvalds * See if the low-level filesystem might want 11851da177e4SLinus Torvalds * to use its own hash.. 11861da177e4SLinus Torvalds */ 11871da177e4SLinus Torvalds if (base->d_op && base->d_op->d_hash) { 11881da177e4SLinus Torvalds err = base->d_op->d_hash(base, name); 11891da177e4SLinus Torvalds dentry = ERR_PTR(err); 11901da177e4SLinus Torvalds if (err < 0) 11911da177e4SLinus Torvalds goto out; 11921da177e4SLinus Torvalds } 11931da177e4SLinus Torvalds 11941da177e4SLinus Torvalds dentry = cached_lookup(base, name, nd); 11951da177e4SLinus Torvalds if (!dentry) { 1196d70b67c8SMiklos Szeredi struct dentry *new; 1197d70b67c8SMiklos Szeredi 1198d70b67c8SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 1199d70b67c8SMiklos Szeredi dentry = ERR_PTR(-ENOENT); 1200d70b67c8SMiklos Szeredi if (IS_DEADDIR(inode)) 1201d70b67c8SMiklos Szeredi goto out; 1202d70b67c8SMiklos Szeredi 1203d70b67c8SMiklos Szeredi new = d_alloc(base, name); 12041da177e4SLinus Torvalds dentry = ERR_PTR(-ENOMEM); 12051da177e4SLinus Torvalds if (!new) 12061da177e4SLinus Torvalds goto out; 12071da177e4SLinus Torvalds dentry = inode->i_op->lookup(inode, new, nd); 12081da177e4SLinus Torvalds if (!dentry) 12091da177e4SLinus Torvalds dentry = new; 12101da177e4SLinus Torvalds else 12111da177e4SLinus Torvalds dput(new); 12121da177e4SLinus Torvalds } 12131da177e4SLinus Torvalds out: 12141da177e4SLinus Torvalds return dentry; 12151da177e4SLinus Torvalds } 12161da177e4SLinus Torvalds 1217057f6c01SJames Morris /* 1218057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1219057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1220057f6c01SJames Morris * SMP-safe. 1221057f6c01SJames Morris */ 1222a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 12231da177e4SLinus Torvalds { 1224eead1911SChristoph Hellwig int err; 1225eead1911SChristoph Hellwig 1226f419a2e3SAl Viro err = inode_permission(nd->path.dentry->d_inode, MAY_EXEC); 1227eead1911SChristoph Hellwig if (err) 1228eead1911SChristoph Hellwig return ERR_PTR(err); 12294ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 12301da177e4SLinus Torvalds } 12311da177e4SLinus Torvalds 1232eead1911SChristoph Hellwig static int __lookup_one_len(const char *name, struct qstr *this, 1233eead1911SChristoph Hellwig struct dentry *base, int len) 12341da177e4SLinus Torvalds { 12351da177e4SLinus Torvalds unsigned long hash; 12361da177e4SLinus Torvalds unsigned int c; 12371da177e4SLinus Torvalds 1238057f6c01SJames Morris this->name = name; 1239057f6c01SJames Morris this->len = len; 12401da177e4SLinus Torvalds if (!len) 1241057f6c01SJames Morris return -EACCES; 12421da177e4SLinus Torvalds 12431da177e4SLinus Torvalds hash = init_name_hash(); 12441da177e4SLinus Torvalds while (len--) { 12451da177e4SLinus Torvalds c = *(const unsigned char *)name++; 12461da177e4SLinus Torvalds if (c == '/' || c == '\0') 1247057f6c01SJames Morris return -EACCES; 12481da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 12491da177e4SLinus Torvalds } 1250057f6c01SJames Morris this->hash = end_name_hash(hash); 1251057f6c01SJames Morris return 0; 1252057f6c01SJames Morris } 12531da177e4SLinus Torvalds 1254eead1911SChristoph Hellwig /** 1255a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1256eead1911SChristoph Hellwig * @name: pathname component to lookup 1257eead1911SChristoph Hellwig * @base: base directory to lookup from 1258eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1259eead1911SChristoph Hellwig * 1260a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1261a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1262eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1263eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1264eead1911SChristoph Hellwig */ 1265057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1266057f6c01SJames Morris { 1267057f6c01SJames Morris int err; 1268057f6c01SJames Morris struct qstr this; 1269057f6c01SJames Morris 12702f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 12712f9092e1SDavid Woodhouse 1272057f6c01SJames Morris err = __lookup_one_len(name, &this, base, len); 1273057f6c01SJames Morris if (err) 1274057f6c01SJames Morris return ERR_PTR(err); 1275eead1911SChristoph Hellwig 1276f419a2e3SAl Viro err = inode_permission(base->d_inode, MAY_EXEC); 1277eead1911SChristoph Hellwig if (err) 1278eead1911SChristoph Hellwig return ERR_PTR(err); 127949705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1280057f6c01SJames Morris } 1281057f6c01SJames Morris 1282eead1911SChristoph Hellwig /** 1283eead1911SChristoph Hellwig * lookup_one_noperm - bad hack for sysfs 1284eead1911SChristoph Hellwig * @name: pathname component to lookup 1285eead1911SChristoph Hellwig * @base: base directory to lookup from 1286eead1911SChristoph Hellwig * 1287eead1911SChristoph Hellwig * This is a variant of lookup_one_len that doesn't perform any permission 1288eead1911SChristoph Hellwig * checks. It's a horrible hack to work around the braindead sysfs 1289eead1911SChristoph Hellwig * architecture and should not be used anywhere else. 1290eead1911SChristoph Hellwig * 1291eead1911SChristoph Hellwig * DON'T USE THIS FUNCTION EVER, thanks. 1292eead1911SChristoph Hellwig */ 1293eead1911SChristoph Hellwig struct dentry *lookup_one_noperm(const char *name, struct dentry *base) 1294057f6c01SJames Morris { 1295057f6c01SJames Morris int err; 1296057f6c01SJames Morris struct qstr this; 1297057f6c01SJames Morris 1298eead1911SChristoph Hellwig err = __lookup_one_len(name, &this, base, strlen(name)); 1299057f6c01SJames Morris if (err) 1300057f6c01SJames Morris return ERR_PTR(err); 1301eead1911SChristoph Hellwig return __lookup_hash(&this, base, NULL); 13021da177e4SLinus Torvalds } 13031da177e4SLinus Torvalds 13042d8f3038SAl Viro int user_path_at(int dfd, const char __user *name, unsigned flags, 13052d8f3038SAl Viro struct path *path) 13061da177e4SLinus Torvalds { 13072d8f3038SAl Viro struct nameidata nd; 13081da177e4SLinus Torvalds char *tmp = getname(name); 13091da177e4SLinus Torvalds int err = PTR_ERR(tmp); 13101da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 13112d8f3038SAl Viro 13122d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 13132d8f3038SAl Viro 13142d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 13151da177e4SLinus Torvalds putname(tmp); 13162d8f3038SAl Viro if (!err) 13172d8f3038SAl Viro *path = nd.path; 13181da177e4SLinus Torvalds } 13191da177e4SLinus Torvalds return err; 13201da177e4SLinus Torvalds } 13211da177e4SLinus Torvalds 13222ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 13232ad94ae6SAl Viro struct nameidata *nd, char **name) 13242ad94ae6SAl Viro { 13252ad94ae6SAl Viro char *s = getname(path); 13262ad94ae6SAl Viro int error; 13272ad94ae6SAl Viro 13282ad94ae6SAl Viro if (IS_ERR(s)) 13292ad94ae6SAl Viro return PTR_ERR(s); 13302ad94ae6SAl Viro 13312ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 13322ad94ae6SAl Viro if (error) 13332ad94ae6SAl Viro putname(s); 13342ad94ae6SAl Viro else 13352ad94ae6SAl Viro *name = s; 13362ad94ae6SAl Viro 13372ad94ae6SAl Viro return error; 13382ad94ae6SAl Viro } 13392ad94ae6SAl Viro 13401da177e4SLinus Torvalds /* 13411da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 13421da177e4SLinus Torvalds * minimal. 13431da177e4SLinus Torvalds */ 13441da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 13451da177e4SLinus Torvalds { 1346da9592edSDavid Howells uid_t fsuid = current_fsuid(); 1347da9592edSDavid Howells 13481da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 13491da177e4SLinus Torvalds return 0; 1350da9592edSDavid Howells if (inode->i_uid == fsuid) 13511da177e4SLinus Torvalds return 0; 1352da9592edSDavid Howells if (dir->i_uid == fsuid) 13531da177e4SLinus Torvalds return 0; 13541da177e4SLinus Torvalds return !capable(CAP_FOWNER); 13551da177e4SLinus Torvalds } 13561da177e4SLinus Torvalds 13571da177e4SLinus Torvalds /* 13581da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 13591da177e4SLinus Torvalds * whether the type of victim is right. 13601da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 13611da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 13621da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 13631da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 13641da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 13651da177e4SLinus Torvalds * a. be owner of dir, or 13661da177e4SLinus Torvalds * b. be owner of victim, or 13671da177e4SLinus Torvalds * c. have CAP_FOWNER capability 13681da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 13691da177e4SLinus Torvalds * links pointing to it. 13701da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 13711da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 13721da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 13731da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 13741da177e4SLinus Torvalds * nfs_async_unlink(). 13751da177e4SLinus Torvalds */ 1376858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 13771da177e4SLinus Torvalds { 13781da177e4SLinus Torvalds int error; 13791da177e4SLinus Torvalds 13801da177e4SLinus Torvalds if (!victim->d_inode) 13811da177e4SLinus Torvalds return -ENOENT; 13821da177e4SLinus Torvalds 13831da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 13845a190ae6SAl Viro audit_inode_child(victim->d_name.name, victim, dir); 13851da177e4SLinus Torvalds 1386f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 13871da177e4SLinus Torvalds if (error) 13881da177e4SLinus Torvalds return error; 13891da177e4SLinus Torvalds if (IS_APPEND(dir)) 13901da177e4SLinus Torvalds return -EPERM; 13911da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 1392f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 13931da177e4SLinus Torvalds return -EPERM; 13941da177e4SLinus Torvalds if (isdir) { 13951da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 13961da177e4SLinus Torvalds return -ENOTDIR; 13971da177e4SLinus Torvalds if (IS_ROOT(victim)) 13981da177e4SLinus Torvalds return -EBUSY; 13991da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 14001da177e4SLinus Torvalds return -EISDIR; 14011da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 14021da177e4SLinus Torvalds return -ENOENT; 14031da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 14041da177e4SLinus Torvalds return -EBUSY; 14051da177e4SLinus Torvalds return 0; 14061da177e4SLinus Torvalds } 14071da177e4SLinus Torvalds 14081da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 14091da177e4SLinus Torvalds * dir. 14101da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 14111da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 14121da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 14131da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 14141da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 14151da177e4SLinus Torvalds */ 1416a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 14171da177e4SLinus Torvalds { 14181da177e4SLinus Torvalds if (child->d_inode) 14191da177e4SLinus Torvalds return -EEXIST; 14201da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 14211da177e4SLinus Torvalds return -ENOENT; 1422f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 14231da177e4SLinus Torvalds } 14241da177e4SLinus Torvalds 14251da177e4SLinus Torvalds /* 14261da177e4SLinus Torvalds * O_DIRECTORY translates into forcing a directory lookup. 14271da177e4SLinus Torvalds */ 14281da177e4SLinus Torvalds static inline int lookup_flags(unsigned int f) 14291da177e4SLinus Torvalds { 14301da177e4SLinus Torvalds unsigned long retval = LOOKUP_FOLLOW; 14311da177e4SLinus Torvalds 14321da177e4SLinus Torvalds if (f & O_NOFOLLOW) 14331da177e4SLinus Torvalds retval &= ~LOOKUP_FOLLOW; 14341da177e4SLinus Torvalds 14351da177e4SLinus Torvalds if (f & O_DIRECTORY) 14361da177e4SLinus Torvalds retval |= LOOKUP_DIRECTORY; 14371da177e4SLinus Torvalds 14381da177e4SLinus Torvalds return retval; 14391da177e4SLinus Torvalds } 14401da177e4SLinus Torvalds 14411da177e4SLinus Torvalds /* 14421da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 14431da177e4SLinus Torvalds */ 14441da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 14451da177e4SLinus Torvalds { 14461da177e4SLinus Torvalds struct dentry *p; 14471da177e4SLinus Torvalds 14481da177e4SLinus Torvalds if (p1 == p2) { 1449f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 14501da177e4SLinus Torvalds return NULL; 14511da177e4SLinus Torvalds } 14521da177e4SLinus Torvalds 1453a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 14541da177e4SLinus Torvalds 1455e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 1456e2761a11SOGAWA Hirofumi if (p) { 1457f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 1458f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 14591da177e4SLinus Torvalds return p; 14601da177e4SLinus Torvalds } 14611da177e4SLinus Torvalds 1462e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 1463e2761a11SOGAWA Hirofumi if (p) { 1464f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1465f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 14661da177e4SLinus Torvalds return p; 14671da177e4SLinus Torvalds } 14681da177e4SLinus Torvalds 1469f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1470f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 14711da177e4SLinus Torvalds return NULL; 14721da177e4SLinus Torvalds } 14731da177e4SLinus Torvalds 14741da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 14751da177e4SLinus Torvalds { 14761b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 14771da177e4SLinus Torvalds if (p1 != p2) { 14781b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 1479a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 14801da177e4SLinus Torvalds } 14811da177e4SLinus Torvalds } 14821da177e4SLinus Torvalds 14831da177e4SLinus Torvalds int vfs_create(struct inode *dir, struct dentry *dentry, int mode, 14841da177e4SLinus Torvalds struct nameidata *nd) 14851da177e4SLinus Torvalds { 1486a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 14871da177e4SLinus Torvalds 14881da177e4SLinus Torvalds if (error) 14891da177e4SLinus Torvalds return error; 14901da177e4SLinus Torvalds 1491acfa4380SAl Viro if (!dir->i_op->create) 14921da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 14931da177e4SLinus Torvalds mode &= S_IALLUGO; 14941da177e4SLinus Torvalds mode |= S_IFREG; 14951da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 14961da177e4SLinus Torvalds if (error) 14971da177e4SLinus Torvalds return error; 14989e3509e2SJan Kara vfs_dq_init(dir); 14991da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 1500a74574aaSStephen Smalley if (!error) 1501f38aa942SAmy Griffis fsnotify_create(dir, dentry); 15021da177e4SLinus Torvalds return error; 15031da177e4SLinus Torvalds } 15041da177e4SLinus Torvalds 15053fb64190SChristoph Hellwig int may_open(struct path *path, int acc_mode, int flag) 15061da177e4SLinus Torvalds { 15073fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 15081da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 15091da177e4SLinus Torvalds int error; 15101da177e4SLinus Torvalds 15111da177e4SLinus Torvalds if (!inode) 15121da177e4SLinus Torvalds return -ENOENT; 15131da177e4SLinus Torvalds 1514c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 1515c8fe8f30SChristoph Hellwig case S_IFLNK: 15161da177e4SLinus Torvalds return -ELOOP; 1517c8fe8f30SChristoph Hellwig case S_IFDIR: 1518c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 15191da177e4SLinus Torvalds return -EISDIR; 1520c8fe8f30SChristoph Hellwig break; 1521c8fe8f30SChristoph Hellwig case S_IFBLK: 1522c8fe8f30SChristoph Hellwig case S_IFCHR: 15233fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 15241da177e4SLinus Torvalds return -EACCES; 1525c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 1526c8fe8f30SChristoph Hellwig case S_IFIFO: 1527c8fe8f30SChristoph Hellwig case S_IFSOCK: 15281da177e4SLinus Torvalds flag &= ~O_TRUNC; 1529c8fe8f30SChristoph Hellwig break; 15304a3fd211SDave Hansen } 1531b41572e9SDave Hansen 15323fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 1533b41572e9SDave Hansen if (error) 1534b41572e9SDave Hansen return error; 15356146f0d5SMimi Zohar 1536cb5629b1SJames Morris error = ima_path_check(path, 1537b9fc745dSMimi Zohar acc_mode & (MAY_READ | MAY_WRITE | MAY_EXEC), 1538b9fc745dSMimi Zohar IMA_COUNT_UPDATE); 15396146f0d5SMimi Zohar if (error) 15406146f0d5SMimi Zohar return error; 15411da177e4SLinus Torvalds /* 15421da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 15431da177e4SLinus Torvalds */ 15441da177e4SLinus Torvalds if (IS_APPEND(inode)) { 15451da177e4SLinus Torvalds if ((flag & FMODE_WRITE) && !(flag & O_APPEND)) 15461da177e4SLinus Torvalds return -EPERM; 15471da177e4SLinus Torvalds if (flag & O_TRUNC) 15481da177e4SLinus Torvalds return -EPERM; 15491da177e4SLinus Torvalds } 15501da177e4SLinus Torvalds 15511da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 15521da177e4SLinus Torvalds if (flag & O_NOATIME) 15533bd858abSSatyam Sharma if (!is_owner_or_cap(inode)) 15541da177e4SLinus Torvalds return -EPERM; 15551da177e4SLinus Torvalds 15561da177e4SLinus Torvalds /* 15571da177e4SLinus Torvalds * Ensure there are no outstanding leases on the file. 15581da177e4SLinus Torvalds */ 15591da177e4SLinus Torvalds error = break_lease(inode, flag); 15601da177e4SLinus Torvalds if (error) 15611da177e4SLinus Torvalds return error; 15621da177e4SLinus Torvalds 15631da177e4SLinus Torvalds if (flag & O_TRUNC) { 15641da177e4SLinus Torvalds error = get_write_access(inode); 15651da177e4SLinus Torvalds if (error) 15661da177e4SLinus Torvalds return error; 15671da177e4SLinus Torvalds 15681da177e4SLinus Torvalds /* 15691da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 15701da177e4SLinus Torvalds */ 15711da177e4SLinus Torvalds error = locks_verify_locked(inode); 1572be6d3e56SKentaro Takeda if (!error) 15733fb64190SChristoph Hellwig error = security_path_truncate(path, 0, 1574be6d3e56SKentaro Takeda ATTR_MTIME|ATTR_CTIME|ATTR_OPEN); 15751da177e4SLinus Torvalds if (!error) { 15769e3509e2SJan Kara vfs_dq_init(inode); 15771da177e4SLinus Torvalds 1578d139d7ffSMiklos Szeredi error = do_truncate(dentry, 0, 1579d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 1580d139d7ffSMiklos Szeredi NULL); 15811da177e4SLinus Torvalds } 15821da177e4SLinus Torvalds put_write_access(inode); 15831da177e4SLinus Torvalds if (error) 15841da177e4SLinus Torvalds return error; 15851da177e4SLinus Torvalds } else 15861da177e4SLinus Torvalds if (flag & FMODE_WRITE) 15879e3509e2SJan Kara vfs_dq_init(inode); 15881da177e4SLinus Torvalds 15891da177e4SLinus Torvalds return 0; 15901da177e4SLinus Torvalds } 15911da177e4SLinus Torvalds 1592d57999e1SDave Hansen /* 1593d57999e1SDave Hansen * Be careful about ever adding any more callers of this 1594d57999e1SDave Hansen * function. Its flags must be in the namei format, not 1595d57999e1SDave Hansen * what get passed to sys_open(). 1596d57999e1SDave Hansen */ 1597d57999e1SDave Hansen static int __open_namei_create(struct nameidata *nd, struct path *path, 1598aab520e2SDave Hansen int flag, int mode) 1599aab520e2SDave Hansen { 1600aab520e2SDave Hansen int error; 16014ac91378SJan Blunck struct dentry *dir = nd->path.dentry; 1602aab520e2SDave Hansen 1603aab520e2SDave Hansen if (!IS_POSIXACL(dir->d_inode)) 1604ce3b0f8dSAl Viro mode &= ~current_umask(); 1605be6d3e56SKentaro Takeda error = security_path_mknod(&nd->path, path->dentry, mode, 0); 1606be6d3e56SKentaro Takeda if (error) 1607be6d3e56SKentaro Takeda goto out_unlock; 1608aab520e2SDave Hansen error = vfs_create(dir->d_inode, path->dentry, mode, nd); 1609be6d3e56SKentaro Takeda out_unlock: 1610aab520e2SDave Hansen mutex_unlock(&dir->d_inode->i_mutex); 16114ac91378SJan Blunck dput(nd->path.dentry); 16124ac91378SJan Blunck nd->path.dentry = path->dentry; 1613aab520e2SDave Hansen if (error) 1614aab520e2SDave Hansen return error; 1615aab520e2SDave Hansen /* Don't check for write permission, don't truncate */ 16163fb64190SChristoph Hellwig return may_open(&nd->path, 0, flag & ~O_TRUNC); 1617aab520e2SDave Hansen } 1618aab520e2SDave Hansen 16191da177e4SLinus Torvalds /* 1620d57999e1SDave Hansen * Note that while the flag value (low two bits) for sys_open means: 1621d57999e1SDave Hansen * 00 - read-only 1622d57999e1SDave Hansen * 01 - write-only 1623d57999e1SDave Hansen * 10 - read-write 1624d57999e1SDave Hansen * 11 - special 1625d57999e1SDave Hansen * it is changed into 1626d57999e1SDave Hansen * 00 - no permissions needed 1627d57999e1SDave Hansen * 01 - read-permission 1628d57999e1SDave Hansen * 10 - write-permission 1629d57999e1SDave Hansen * 11 - read-write 1630d57999e1SDave Hansen * for the internal routines (ie open_namei()/follow_link() etc) 1631d57999e1SDave Hansen * This is more logical, and also allows the 00 "no perm needed" 1632d57999e1SDave Hansen * to be used for symlinks (where the permissions are checked 1633d57999e1SDave Hansen * later). 1634d57999e1SDave Hansen * 1635d57999e1SDave Hansen */ 1636d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 1637d57999e1SDave Hansen { 1638d57999e1SDave Hansen if ((flag+1) & O_ACCMODE) 1639d57999e1SDave Hansen flag++; 1640d57999e1SDave Hansen return flag; 1641d57999e1SDave Hansen } 1642d57999e1SDave Hansen 16434a3fd211SDave Hansen static int open_will_write_to_fs(int flag, struct inode *inode) 16444a3fd211SDave Hansen { 1645d57999e1SDave Hansen /* 16464a3fd211SDave Hansen * We'll never write to the fs underlying 16474a3fd211SDave Hansen * a device file. 16484a3fd211SDave Hansen */ 16494a3fd211SDave Hansen if (special_file(inode->i_mode)) 16504a3fd211SDave Hansen return 0; 16514a3fd211SDave Hansen return (flag & O_TRUNC); 16524a3fd211SDave Hansen } 16534a3fd211SDave Hansen 16544a3fd211SDave Hansen /* 16554a3fd211SDave Hansen * Note that the low bits of the passed in "open_flag" 16564a3fd211SDave Hansen * are not the same as in the local variable "flag". See 16574a3fd211SDave Hansen * open_to_namei_flags() for more details. 16581da177e4SLinus Torvalds */ 1659a70e65dfSChristoph Hellwig struct file *do_filp_open(int dfd, const char *pathname, 16606e8341a1SAl Viro int open_flag, int mode, int acc_mode) 16611da177e4SLinus Torvalds { 16624a3fd211SDave Hansen struct file *filp; 1663a70e65dfSChristoph Hellwig struct nameidata nd; 16646e8341a1SAl Viro int error; 16654e7506e4SAl Viro struct path path; 16661da177e4SLinus Torvalds struct dentry *dir; 16671da177e4SLinus Torvalds int count = 0; 16684a3fd211SDave Hansen int will_write; 1669d57999e1SDave Hansen int flag = open_to_namei_flags(open_flag); 16701da177e4SLinus Torvalds 16716e8341a1SAl Viro if (!acc_mode) 1672b77b0646SAl Viro acc_mode = MAY_OPEN | ACC_MODE(flag); 16731da177e4SLinus Torvalds 1674834f2a4aSTrond Myklebust /* O_TRUNC implies we need access checks for write permissions */ 1675834f2a4aSTrond Myklebust if (flag & O_TRUNC) 1676834f2a4aSTrond Myklebust acc_mode |= MAY_WRITE; 1677834f2a4aSTrond Myklebust 16781da177e4SLinus Torvalds /* Allow the LSM permission hook to distinguish append 16791da177e4SLinus Torvalds access from general write access. */ 16801da177e4SLinus Torvalds if (flag & O_APPEND) 16811da177e4SLinus Torvalds acc_mode |= MAY_APPEND; 16821da177e4SLinus Torvalds 16831da177e4SLinus Torvalds /* 16841da177e4SLinus Torvalds * The simplest case - just a plain lookup. 16851da177e4SLinus Torvalds */ 16861da177e4SLinus Torvalds if (!(flag & O_CREAT)) { 16875590ff0dSUlrich Drepper error = path_lookup_open(dfd, pathname, lookup_flags(flag), 1688a70e65dfSChristoph Hellwig &nd, flag); 16891da177e4SLinus Torvalds if (error) 1690a70e65dfSChristoph Hellwig return ERR_PTR(error); 16911da177e4SLinus Torvalds goto ok; 16921da177e4SLinus Torvalds } 16931da177e4SLinus Torvalds 16941da177e4SLinus Torvalds /* 16951da177e4SLinus Torvalds * Create - we need to know the parent. 16961da177e4SLinus Torvalds */ 16979b4a9b14SAl Viro error = path_init(dfd, pathname, LOOKUP_PARENT, &nd); 16981da177e4SLinus Torvalds if (error) 1699a70e65dfSChristoph Hellwig return ERR_PTR(error); 17009b4a9b14SAl Viro error = path_walk(pathname, &nd); 17019b4a9b14SAl Viro if (error) 17029b4a9b14SAl Viro return ERR_PTR(error); 17039b4a9b14SAl Viro if (unlikely(!audit_dummy_context())) 17049b4a9b14SAl Viro audit_inode(pathname, nd.path.dentry); 17051da177e4SLinus Torvalds 17061da177e4SLinus Torvalds /* 17071da177e4SLinus Torvalds * We have the parent and last component. First of all, check 17081da177e4SLinus Torvalds * that we are not asked to creat(2) an obvious directory - that 17091da177e4SLinus Torvalds * will not do. 17101da177e4SLinus Torvalds */ 17111da177e4SLinus Torvalds error = -EISDIR; 1712a70e65dfSChristoph Hellwig if (nd.last_type != LAST_NORM || nd.last.name[nd.last.len]) 17138737f3a1SAl Viro goto exit_parent; 17141da177e4SLinus Torvalds 17158737f3a1SAl Viro error = -ENFILE; 17168737f3a1SAl Viro filp = get_empty_filp(); 17178737f3a1SAl Viro if (filp == NULL) 17188737f3a1SAl Viro goto exit_parent; 17198737f3a1SAl Viro nd.intent.open.file = filp; 17208737f3a1SAl Viro nd.intent.open.flags = flag; 17218737f3a1SAl Viro nd.intent.open.create_mode = mode; 1722a70e65dfSChristoph Hellwig dir = nd.path.dentry; 1723a70e65dfSChristoph Hellwig nd.flags &= ~LOOKUP_PARENT; 17248737f3a1SAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_OPEN; 17253516586aSAl Viro if (flag & O_EXCL) 17263516586aSAl Viro nd.flags |= LOOKUP_EXCL; 17271b1dcc1bSJes Sorensen mutex_lock(&dir->d_inode->i_mutex); 1728a70e65dfSChristoph Hellwig path.dentry = lookup_hash(&nd); 1729a70e65dfSChristoph Hellwig path.mnt = nd.path.mnt; 17301da177e4SLinus Torvalds 17311da177e4SLinus Torvalds do_last: 17324e7506e4SAl Viro error = PTR_ERR(path.dentry); 17334e7506e4SAl Viro if (IS_ERR(path.dentry)) { 17341b1dcc1bSJes Sorensen mutex_unlock(&dir->d_inode->i_mutex); 17351da177e4SLinus Torvalds goto exit; 17361da177e4SLinus Torvalds } 17371da177e4SLinus Torvalds 1738a70e65dfSChristoph Hellwig if (IS_ERR(nd.intent.open.file)) { 1739a70e65dfSChristoph Hellwig error = PTR_ERR(nd.intent.open.file); 17404a3fd211SDave Hansen goto exit_mutex_unlock; 17414af4c52fSOleg Drokin } 17424af4c52fSOleg Drokin 17431da177e4SLinus Torvalds /* Negative dentry, just create the file */ 17444e7506e4SAl Viro if (!path.dentry->d_inode) { 17454a3fd211SDave Hansen /* 17464a3fd211SDave Hansen * This write is needed to ensure that a 17474a3fd211SDave Hansen * ro->rw transition does not occur between 17484a3fd211SDave Hansen * the time when the file is created and when 17494a3fd211SDave Hansen * a permanent write count is taken through 17504a3fd211SDave Hansen * the 'struct file' in nameidata_to_filp(). 17514a3fd211SDave Hansen */ 17524a3fd211SDave Hansen error = mnt_want_write(nd.path.mnt); 17531da177e4SLinus Torvalds if (error) 17544a3fd211SDave Hansen goto exit_mutex_unlock; 17554a3fd211SDave Hansen error = __open_namei_create(&nd, &path, flag, mode); 17564a3fd211SDave Hansen if (error) { 17574a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 17581da177e4SLinus Torvalds goto exit; 17594a3fd211SDave Hansen } 17604a3fd211SDave Hansen filp = nameidata_to_filp(&nd, open_flag); 17614a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 17624a3fd211SDave Hansen return filp; 17631da177e4SLinus Torvalds } 17641da177e4SLinus Torvalds 17651da177e4SLinus Torvalds /* 17661da177e4SLinus Torvalds * It already exists. 17671da177e4SLinus Torvalds */ 17681b1dcc1bSJes Sorensen mutex_unlock(&dir->d_inode->i_mutex); 17695a190ae6SAl Viro audit_inode(pathname, path.dentry); 17701da177e4SLinus Torvalds 17711da177e4SLinus Torvalds error = -EEXIST; 17721da177e4SLinus Torvalds if (flag & O_EXCL) 17731da177e4SLinus Torvalds goto exit_dput; 17741da177e4SLinus Torvalds 1775e13b210fSAl Viro if (__follow_mount(&path)) { 17761da177e4SLinus Torvalds error = -ELOOP; 1777ba7a4c1aSAl Viro if (flag & O_NOFOLLOW) 1778ba7a4c1aSAl Viro goto exit_dput; 17791da177e4SLinus Torvalds } 17803e2efce0SAmy Griffis 17811da177e4SLinus Torvalds error = -ENOENT; 17824e7506e4SAl Viro if (!path.dentry->d_inode) 17831da177e4SLinus Torvalds goto exit_dput; 1784acfa4380SAl Viro if (path.dentry->d_inode->i_op->follow_link) 17851da177e4SLinus Torvalds goto do_link; 17861da177e4SLinus Torvalds 1787a70e65dfSChristoph Hellwig path_to_nameidata(&path, &nd); 17881da177e4SLinus Torvalds error = -EISDIR; 17894e7506e4SAl Viro if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode)) 17901da177e4SLinus Torvalds goto exit; 17911da177e4SLinus Torvalds ok: 17924a3fd211SDave Hansen /* 17934a3fd211SDave Hansen * Consider: 17944a3fd211SDave Hansen * 1. may_open() truncates a file 17954a3fd211SDave Hansen * 2. a rw->ro mount transition occurs 17964a3fd211SDave Hansen * 3. nameidata_to_filp() fails due to 17974a3fd211SDave Hansen * the ro mount. 17984a3fd211SDave Hansen * That would be inconsistent, and should 17994a3fd211SDave Hansen * be avoided. Taking this mnt write here 18004a3fd211SDave Hansen * ensures that (2) can not occur. 18014a3fd211SDave Hansen */ 18024a3fd211SDave Hansen will_write = open_will_write_to_fs(flag, nd.path.dentry->d_inode); 18034a3fd211SDave Hansen if (will_write) { 18044a3fd211SDave Hansen error = mnt_want_write(nd.path.mnt); 18051da177e4SLinus Torvalds if (error) 18061da177e4SLinus Torvalds goto exit; 18074a3fd211SDave Hansen } 18083fb64190SChristoph Hellwig error = may_open(&nd.path, acc_mode, flag); 18094a3fd211SDave Hansen if (error) { 18104a3fd211SDave Hansen if (will_write) 18114a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 18124a3fd211SDave Hansen goto exit; 18134a3fd211SDave Hansen } 18144a3fd211SDave Hansen filp = nameidata_to_filp(&nd, open_flag); 18154a3fd211SDave Hansen /* 18164a3fd211SDave Hansen * It is now safe to drop the mnt write 18174a3fd211SDave Hansen * because the filp has had a write taken 18184a3fd211SDave Hansen * on its behalf. 18194a3fd211SDave Hansen */ 18204a3fd211SDave Hansen if (will_write) 18214a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 18224a3fd211SDave Hansen return filp; 18231da177e4SLinus Torvalds 18244a3fd211SDave Hansen exit_mutex_unlock: 18254a3fd211SDave Hansen mutex_unlock(&dir->d_inode->i_mutex); 18261da177e4SLinus Torvalds exit_dput: 1827a70e65dfSChristoph Hellwig path_put_conditional(&path, &nd); 18281da177e4SLinus Torvalds exit: 1829a70e65dfSChristoph Hellwig if (!IS_ERR(nd.intent.open.file)) 1830a70e65dfSChristoph Hellwig release_open_intent(&nd); 18318737f3a1SAl Viro exit_parent: 18322a737871SAl Viro if (nd.root.mnt) 18332a737871SAl Viro path_put(&nd.root); 1834a70e65dfSChristoph Hellwig path_put(&nd.path); 1835a70e65dfSChristoph Hellwig return ERR_PTR(error); 18361da177e4SLinus Torvalds 18371da177e4SLinus Torvalds do_link: 18381da177e4SLinus Torvalds error = -ELOOP; 18391da177e4SLinus Torvalds if (flag & O_NOFOLLOW) 18401da177e4SLinus Torvalds goto exit_dput; 18411da177e4SLinus Torvalds /* 18421da177e4SLinus Torvalds * This is subtle. Instead of calling do_follow_link() we do the 18431da177e4SLinus Torvalds * thing by hands. The reason is that this way we have zero link_count 18441da177e4SLinus Torvalds * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT. 18451da177e4SLinus Torvalds * After that we have the parent and last component, i.e. 18461da177e4SLinus Torvalds * we are in the same situation as after the first path_walk(). 18471da177e4SLinus Torvalds * Well, almost - if the last component is normal we get its copy 18481da177e4SLinus Torvalds * stored in nd->last.name and we will have to putname() it when we 18491da177e4SLinus Torvalds * are done. Procfs-like symlinks just set LAST_BIND. 18501da177e4SLinus Torvalds */ 1851a70e65dfSChristoph Hellwig nd.flags |= LOOKUP_PARENT; 1852a70e65dfSChristoph Hellwig error = security_inode_follow_link(path.dentry, &nd); 18531da177e4SLinus Torvalds if (error) 18541da177e4SLinus Torvalds goto exit_dput; 1855a70e65dfSChristoph Hellwig error = __do_follow_link(&path, &nd); 1856de459215SKirill Korotaev if (error) { 1857de459215SKirill Korotaev /* Does someone understand code flow here? Or it is only 1858de459215SKirill Korotaev * me so stupid? Anathema to whoever designed this non-sense 1859de459215SKirill Korotaev * with "intent.open". 1860de459215SKirill Korotaev */ 1861a70e65dfSChristoph Hellwig release_open_intent(&nd); 1862a70e65dfSChristoph Hellwig return ERR_PTR(error); 1863de459215SKirill Korotaev } 1864a70e65dfSChristoph Hellwig nd.flags &= ~LOOKUP_PARENT; 1865a70e65dfSChristoph Hellwig if (nd.last_type == LAST_BIND) 18661da177e4SLinus Torvalds goto ok; 18671da177e4SLinus Torvalds error = -EISDIR; 1868a70e65dfSChristoph Hellwig if (nd.last_type != LAST_NORM) 18691da177e4SLinus Torvalds goto exit; 1870a70e65dfSChristoph Hellwig if (nd.last.name[nd.last.len]) { 1871a70e65dfSChristoph Hellwig __putname(nd.last.name); 18721da177e4SLinus Torvalds goto exit; 18731da177e4SLinus Torvalds } 18741da177e4SLinus Torvalds error = -ELOOP; 18751da177e4SLinus Torvalds if (count++==32) { 1876a70e65dfSChristoph Hellwig __putname(nd.last.name); 18771da177e4SLinus Torvalds goto exit; 18781da177e4SLinus Torvalds } 1879a70e65dfSChristoph Hellwig dir = nd.path.dentry; 18801b1dcc1bSJes Sorensen mutex_lock(&dir->d_inode->i_mutex); 1881a70e65dfSChristoph Hellwig path.dentry = lookup_hash(&nd); 1882a70e65dfSChristoph Hellwig path.mnt = nd.path.mnt; 1883a70e65dfSChristoph Hellwig __putname(nd.last.name); 18841da177e4SLinus Torvalds goto do_last; 18851da177e4SLinus Torvalds } 18861da177e4SLinus Torvalds 18871da177e4SLinus Torvalds /** 1888a70e65dfSChristoph Hellwig * filp_open - open file and return file pointer 1889a70e65dfSChristoph Hellwig * 1890a70e65dfSChristoph Hellwig * @filename: path to open 1891a70e65dfSChristoph Hellwig * @flags: open flags as per the open(2) second argument 1892a70e65dfSChristoph Hellwig * @mode: mode for the new file if O_CREAT is set, else ignored 1893a70e65dfSChristoph Hellwig * 1894a70e65dfSChristoph Hellwig * This is the helper to open a file from kernelspace if you really 1895a70e65dfSChristoph Hellwig * have to. But in generally you should not do this, so please move 1896a70e65dfSChristoph Hellwig * along, nothing to see here.. 1897a70e65dfSChristoph Hellwig */ 1898a70e65dfSChristoph Hellwig struct file *filp_open(const char *filename, int flags, int mode) 1899a70e65dfSChristoph Hellwig { 19006e8341a1SAl Viro return do_filp_open(AT_FDCWD, filename, flags, mode, 0); 1901a70e65dfSChristoph Hellwig } 1902a70e65dfSChristoph Hellwig EXPORT_SYMBOL(filp_open); 1903a70e65dfSChristoph Hellwig 1904a70e65dfSChristoph Hellwig /** 19051da177e4SLinus Torvalds * lookup_create - lookup a dentry, creating it if it doesn't exist 19061da177e4SLinus Torvalds * @nd: nameidata info 19071da177e4SLinus Torvalds * @is_dir: directory flag 19081da177e4SLinus Torvalds * 19091da177e4SLinus Torvalds * Simple function to lookup and return a dentry and create it 19101da177e4SLinus Torvalds * if it doesn't exist. Is SMP-safe. 1911c663e5d8SChristoph Hellwig * 19124ac91378SJan Blunck * Returns with nd->path.dentry->d_inode->i_mutex locked. 19131da177e4SLinus Torvalds */ 19141da177e4SLinus Torvalds struct dentry *lookup_create(struct nameidata *nd, int is_dir) 19151da177e4SLinus Torvalds { 1916c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 19171da177e4SLinus Torvalds 19184ac91378SJan Blunck mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 1919c663e5d8SChristoph Hellwig /* 1920c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 1921c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 1922c663e5d8SChristoph Hellwig */ 19231da177e4SLinus Torvalds if (nd->last_type != LAST_NORM) 19241da177e4SLinus Torvalds goto fail; 19251da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 19263516586aSAl Viro nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL; 1927a634904aSASANO Masahiro nd->intent.open.flags = O_EXCL; 1928c663e5d8SChristoph Hellwig 1929c663e5d8SChristoph Hellwig /* 1930c663e5d8SChristoph Hellwig * Do the final lookup. 1931c663e5d8SChristoph Hellwig */ 193249705b77SChristoph Hellwig dentry = lookup_hash(nd); 19331da177e4SLinus Torvalds if (IS_ERR(dentry)) 19341da177e4SLinus Torvalds goto fail; 1935c663e5d8SChristoph Hellwig 1936e9baf6e5SAl Viro if (dentry->d_inode) 1937e9baf6e5SAl Viro goto eexist; 1938c663e5d8SChristoph Hellwig /* 1939c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 1940c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 1941c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 1942c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 1943c663e5d8SChristoph Hellwig */ 1944e9baf6e5SAl Viro if (unlikely(!is_dir && nd->last.name[nd->last.len])) { 19451da177e4SLinus Torvalds dput(dentry); 19461da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 1947e9baf6e5SAl Viro } 1948e9baf6e5SAl Viro return dentry; 1949e9baf6e5SAl Viro eexist: 1950e9baf6e5SAl Viro dput(dentry); 1951e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 19521da177e4SLinus Torvalds fail: 19531da177e4SLinus Torvalds return dentry; 19541da177e4SLinus Torvalds } 1955f81a0bffSChristoph Hellwig EXPORT_SYMBOL_GPL(lookup_create); 19561da177e4SLinus Torvalds 19571da177e4SLinus Torvalds int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 19581da177e4SLinus Torvalds { 1959a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 19601da177e4SLinus Torvalds 19611da177e4SLinus Torvalds if (error) 19621da177e4SLinus Torvalds return error; 19631da177e4SLinus Torvalds 19641da177e4SLinus Torvalds if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 19651da177e4SLinus Torvalds return -EPERM; 19661da177e4SLinus Torvalds 1967acfa4380SAl Viro if (!dir->i_op->mknod) 19681da177e4SLinus Torvalds return -EPERM; 19691da177e4SLinus Torvalds 197008ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 197108ce5f16SSerge E. Hallyn if (error) 197208ce5f16SSerge E. Hallyn return error; 197308ce5f16SSerge E. Hallyn 19741da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 19751da177e4SLinus Torvalds if (error) 19761da177e4SLinus Torvalds return error; 19771da177e4SLinus Torvalds 19789e3509e2SJan Kara vfs_dq_init(dir); 19791da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 1980a74574aaSStephen Smalley if (!error) 1981f38aa942SAmy Griffis fsnotify_create(dir, dentry); 19821da177e4SLinus Torvalds return error; 19831da177e4SLinus Torvalds } 19841da177e4SLinus Torvalds 1985463c3197SDave Hansen static int may_mknod(mode_t mode) 1986463c3197SDave Hansen { 1987463c3197SDave Hansen switch (mode & S_IFMT) { 1988463c3197SDave Hansen case S_IFREG: 1989463c3197SDave Hansen case S_IFCHR: 1990463c3197SDave Hansen case S_IFBLK: 1991463c3197SDave Hansen case S_IFIFO: 1992463c3197SDave Hansen case S_IFSOCK: 1993463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 1994463c3197SDave Hansen return 0; 1995463c3197SDave Hansen case S_IFDIR: 1996463c3197SDave Hansen return -EPERM; 1997463c3197SDave Hansen default: 1998463c3197SDave Hansen return -EINVAL; 1999463c3197SDave Hansen } 2000463c3197SDave Hansen } 2001463c3197SDave Hansen 20022e4d0924SHeiko Carstens SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode, 20032e4d0924SHeiko Carstens unsigned, dev) 20041da177e4SLinus Torvalds { 20052ad94ae6SAl Viro int error; 20061da177e4SLinus Torvalds char *tmp; 20071da177e4SLinus Torvalds struct dentry *dentry; 20081da177e4SLinus Torvalds struct nameidata nd; 20091da177e4SLinus Torvalds 20101da177e4SLinus Torvalds if (S_ISDIR(mode)) 20111da177e4SLinus Torvalds return -EPERM; 20121da177e4SLinus Torvalds 20132ad94ae6SAl Viro error = user_path_parent(dfd, filename, &nd, &tmp); 20141da177e4SLinus Torvalds if (error) 20152ad94ae6SAl Viro return error; 20162ad94ae6SAl Viro 20171da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 2018463c3197SDave Hansen if (IS_ERR(dentry)) { 20191da177e4SLinus Torvalds error = PTR_ERR(dentry); 2020463c3197SDave Hansen goto out_unlock; 2021463c3197SDave Hansen } 20224ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2023ce3b0f8dSAl Viro mode &= ~current_umask(); 2024463c3197SDave Hansen error = may_mknod(mode); 2025463c3197SDave Hansen if (error) 2026463c3197SDave Hansen goto out_dput; 2027463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2028463c3197SDave Hansen if (error) 2029463c3197SDave Hansen goto out_dput; 2030be6d3e56SKentaro Takeda error = security_path_mknod(&nd.path, dentry, mode, dev); 2031be6d3e56SKentaro Takeda if (error) 2032be6d3e56SKentaro Takeda goto out_drop_write; 20331da177e4SLinus Torvalds switch (mode & S_IFMT) { 20341da177e4SLinus Torvalds case 0: case S_IFREG: 20354ac91378SJan Blunck error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); 20361da177e4SLinus Torvalds break; 20371da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 20384ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, 20391da177e4SLinus Torvalds new_decode_dev(dev)); 20401da177e4SLinus Torvalds break; 20411da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 20424ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); 20431da177e4SLinus Torvalds break; 20441da177e4SLinus Torvalds } 2045be6d3e56SKentaro Takeda out_drop_write: 2046463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2047463c3197SDave Hansen out_dput: 20481da177e4SLinus Torvalds dput(dentry); 2049463c3197SDave Hansen out_unlock: 20504ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 20511d957f9bSJan Blunck path_put(&nd.path); 20521da177e4SLinus Torvalds putname(tmp); 20531da177e4SLinus Torvalds 20541da177e4SLinus Torvalds return error; 20551da177e4SLinus Torvalds } 20561da177e4SLinus Torvalds 20573480b257SHeiko Carstens SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev) 20585590ff0dSUlrich Drepper { 20595590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 20605590ff0dSUlrich Drepper } 20615590ff0dSUlrich Drepper 20621da177e4SLinus Torvalds int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 20631da177e4SLinus Torvalds { 2064a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 20651da177e4SLinus Torvalds 20661da177e4SLinus Torvalds if (error) 20671da177e4SLinus Torvalds return error; 20681da177e4SLinus Torvalds 2069acfa4380SAl Viro if (!dir->i_op->mkdir) 20701da177e4SLinus Torvalds return -EPERM; 20711da177e4SLinus Torvalds 20721da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 20731da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 20741da177e4SLinus Torvalds if (error) 20751da177e4SLinus Torvalds return error; 20761da177e4SLinus Torvalds 20779e3509e2SJan Kara vfs_dq_init(dir); 20781da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2079a74574aaSStephen Smalley if (!error) 2080f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 20811da177e4SLinus Torvalds return error; 20821da177e4SLinus Torvalds } 20831da177e4SLinus Torvalds 20842e4d0924SHeiko Carstens SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode) 20851da177e4SLinus Torvalds { 20861da177e4SLinus Torvalds int error = 0; 20871da177e4SLinus Torvalds char * tmp; 20886902d925SDave Hansen struct dentry *dentry; 20896902d925SDave Hansen struct nameidata nd; 20901da177e4SLinus Torvalds 20912ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &tmp); 20922ad94ae6SAl Viro if (error) 20936902d925SDave Hansen goto out_err; 20941da177e4SLinus Torvalds 20951da177e4SLinus Torvalds dentry = lookup_create(&nd, 1); 20961da177e4SLinus Torvalds error = PTR_ERR(dentry); 20976902d925SDave Hansen if (IS_ERR(dentry)) 20986902d925SDave Hansen goto out_unlock; 20996902d925SDave Hansen 21004ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2101ce3b0f8dSAl Viro mode &= ~current_umask(); 2102463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2103463c3197SDave Hansen if (error) 2104463c3197SDave Hansen goto out_dput; 2105be6d3e56SKentaro Takeda error = security_path_mkdir(&nd.path, dentry, mode); 2106be6d3e56SKentaro Takeda if (error) 2107be6d3e56SKentaro Takeda goto out_drop_write; 21084ac91378SJan Blunck error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); 2109be6d3e56SKentaro Takeda out_drop_write: 2110463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2111463c3197SDave Hansen out_dput: 21121da177e4SLinus Torvalds dput(dentry); 21136902d925SDave Hansen out_unlock: 21144ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 21151d957f9bSJan Blunck path_put(&nd.path); 21161da177e4SLinus Torvalds putname(tmp); 21176902d925SDave Hansen out_err: 21181da177e4SLinus Torvalds return error; 21191da177e4SLinus Torvalds } 21201da177e4SLinus Torvalds 21213cdad428SHeiko Carstens SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode) 21225590ff0dSUlrich Drepper { 21235590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 21245590ff0dSUlrich Drepper } 21255590ff0dSUlrich Drepper 21261da177e4SLinus Torvalds /* 21271da177e4SLinus Torvalds * We try to drop the dentry early: we should have 21281da177e4SLinus Torvalds * a usage count of 2 if we're the only user of this 21291da177e4SLinus Torvalds * dentry, and if that is true (possibly after pruning 21301da177e4SLinus Torvalds * the dcache), then we drop the dentry now. 21311da177e4SLinus Torvalds * 21321da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 21331da177e4SLinus Torvalds * do a 21341da177e4SLinus Torvalds * 21351da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 21361da177e4SLinus Torvalds * return -EBUSY; 21371da177e4SLinus Torvalds * 21381da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 21391da177e4SLinus Torvalds * that is still in use by something else.. 21401da177e4SLinus Torvalds */ 21411da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 21421da177e4SLinus Torvalds { 21431da177e4SLinus Torvalds dget(dentry); 21441da177e4SLinus Torvalds shrink_dcache_parent(dentry); 21451da177e4SLinus Torvalds spin_lock(&dcache_lock); 21461da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 21471da177e4SLinus Torvalds if (atomic_read(&dentry->d_count) == 2) 21481da177e4SLinus Torvalds __d_drop(dentry); 21491da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 21501da177e4SLinus Torvalds spin_unlock(&dcache_lock); 21511da177e4SLinus Torvalds } 21521da177e4SLinus Torvalds 21531da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 21541da177e4SLinus Torvalds { 21551da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 21561da177e4SLinus Torvalds 21571da177e4SLinus Torvalds if (error) 21581da177e4SLinus Torvalds return error; 21591da177e4SLinus Torvalds 2160acfa4380SAl Viro if (!dir->i_op->rmdir) 21611da177e4SLinus Torvalds return -EPERM; 21621da177e4SLinus Torvalds 21639e3509e2SJan Kara vfs_dq_init(dir); 21641da177e4SLinus Torvalds 21651b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 21661da177e4SLinus Torvalds dentry_unhash(dentry); 21671da177e4SLinus Torvalds if (d_mountpoint(dentry)) 21681da177e4SLinus Torvalds error = -EBUSY; 21691da177e4SLinus Torvalds else { 21701da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 21711da177e4SLinus Torvalds if (!error) { 21721da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 21731da177e4SLinus Torvalds if (!error) 21741da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 21751da177e4SLinus Torvalds } 21761da177e4SLinus Torvalds } 21771b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 21781da177e4SLinus Torvalds if (!error) { 21791da177e4SLinus Torvalds d_delete(dentry); 21801da177e4SLinus Torvalds } 21811da177e4SLinus Torvalds dput(dentry); 21821da177e4SLinus Torvalds 21831da177e4SLinus Torvalds return error; 21841da177e4SLinus Torvalds } 21851da177e4SLinus Torvalds 21865590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 21871da177e4SLinus Torvalds { 21881da177e4SLinus Torvalds int error = 0; 21891da177e4SLinus Torvalds char * name; 21901da177e4SLinus Torvalds struct dentry *dentry; 21911da177e4SLinus Torvalds struct nameidata nd; 21921da177e4SLinus Torvalds 21932ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 21941da177e4SLinus Torvalds if (error) 21952ad94ae6SAl Viro return error; 21961da177e4SLinus Torvalds 21971da177e4SLinus Torvalds switch(nd.last_type) { 21981da177e4SLinus Torvalds case LAST_DOTDOT: 21991da177e4SLinus Torvalds error = -ENOTEMPTY; 22001da177e4SLinus Torvalds goto exit1; 22011da177e4SLinus Torvalds case LAST_DOT: 22021da177e4SLinus Torvalds error = -EINVAL; 22031da177e4SLinus Torvalds goto exit1; 22041da177e4SLinus Torvalds case LAST_ROOT: 22051da177e4SLinus Torvalds error = -EBUSY; 22061da177e4SLinus Torvalds goto exit1; 22071da177e4SLinus Torvalds } 22080612d9fbSOGAWA Hirofumi 22090612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 22100612d9fbSOGAWA Hirofumi 22114ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 221249705b77SChristoph Hellwig dentry = lookup_hash(&nd); 22131da177e4SLinus Torvalds error = PTR_ERR(dentry); 22146902d925SDave Hansen if (IS_ERR(dentry)) 22156902d925SDave Hansen goto exit2; 22160622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 22170622753bSDave Hansen if (error) 22180622753bSDave Hansen goto exit3; 2219be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 2220be6d3e56SKentaro Takeda if (error) 2221be6d3e56SKentaro Takeda goto exit4; 22224ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 2223be6d3e56SKentaro Takeda exit4: 22240622753bSDave Hansen mnt_drop_write(nd.path.mnt); 22250622753bSDave Hansen exit3: 22261da177e4SLinus Torvalds dput(dentry); 22276902d925SDave Hansen exit2: 22284ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 22291da177e4SLinus Torvalds exit1: 22301d957f9bSJan Blunck path_put(&nd.path); 22311da177e4SLinus Torvalds putname(name); 22321da177e4SLinus Torvalds return error; 22331da177e4SLinus Torvalds } 22341da177e4SLinus Torvalds 22353cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 22365590ff0dSUlrich Drepper { 22375590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 22385590ff0dSUlrich Drepper } 22395590ff0dSUlrich Drepper 22401da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 22411da177e4SLinus Torvalds { 22421da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 22431da177e4SLinus Torvalds 22441da177e4SLinus Torvalds if (error) 22451da177e4SLinus Torvalds return error; 22461da177e4SLinus Torvalds 2247acfa4380SAl Viro if (!dir->i_op->unlink) 22481da177e4SLinus Torvalds return -EPERM; 22491da177e4SLinus Torvalds 22509e3509e2SJan Kara vfs_dq_init(dir); 22511da177e4SLinus Torvalds 22521b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 22531da177e4SLinus Torvalds if (d_mountpoint(dentry)) 22541da177e4SLinus Torvalds error = -EBUSY; 22551da177e4SLinus Torvalds else { 22561da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 22571da177e4SLinus Torvalds if (!error) 22581da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 22591da177e4SLinus Torvalds } 22601b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 22611da177e4SLinus Torvalds 22621da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 22631da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2264ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 22651da177e4SLinus Torvalds d_delete(dentry); 22661da177e4SLinus Torvalds } 22670eeca283SRobert Love 22681da177e4SLinus Torvalds return error; 22691da177e4SLinus Torvalds } 22701da177e4SLinus Torvalds 22711da177e4SLinus Torvalds /* 22721da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 22731b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 22741da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 22751da177e4SLinus Torvalds * while waiting on the I/O. 22761da177e4SLinus Torvalds */ 22775590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 22781da177e4SLinus Torvalds { 22792ad94ae6SAl Viro int error; 22801da177e4SLinus Torvalds char *name; 22811da177e4SLinus Torvalds struct dentry *dentry; 22821da177e4SLinus Torvalds struct nameidata nd; 22831da177e4SLinus Torvalds struct inode *inode = NULL; 22841da177e4SLinus Torvalds 22852ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 22861da177e4SLinus Torvalds if (error) 22872ad94ae6SAl Viro return error; 22882ad94ae6SAl Viro 22891da177e4SLinus Torvalds error = -EISDIR; 22901da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 22911da177e4SLinus Torvalds goto exit1; 22920612d9fbSOGAWA Hirofumi 22930612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 22940612d9fbSOGAWA Hirofumi 22954ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 229649705b77SChristoph Hellwig dentry = lookup_hash(&nd); 22971da177e4SLinus Torvalds error = PTR_ERR(dentry); 22981da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 22991da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 23001da177e4SLinus Torvalds if (nd.last.name[nd.last.len]) 23011da177e4SLinus Torvalds goto slashes; 23021da177e4SLinus Torvalds inode = dentry->d_inode; 23031da177e4SLinus Torvalds if (inode) 23041da177e4SLinus Torvalds atomic_inc(&inode->i_count); 23050622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 23060622753bSDave Hansen if (error) 23070622753bSDave Hansen goto exit2; 2308be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 2309be6d3e56SKentaro Takeda if (error) 2310be6d3e56SKentaro Takeda goto exit3; 23114ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 2312be6d3e56SKentaro Takeda exit3: 23130622753bSDave Hansen mnt_drop_write(nd.path.mnt); 23141da177e4SLinus Torvalds exit2: 23151da177e4SLinus Torvalds dput(dentry); 23161da177e4SLinus Torvalds } 23174ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 23181da177e4SLinus Torvalds if (inode) 23191da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 23201da177e4SLinus Torvalds exit1: 23211d957f9bSJan Blunck path_put(&nd.path); 23221da177e4SLinus Torvalds putname(name); 23231da177e4SLinus Torvalds return error; 23241da177e4SLinus Torvalds 23251da177e4SLinus Torvalds slashes: 23261da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 23271da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 23281da177e4SLinus Torvalds goto exit2; 23291da177e4SLinus Torvalds } 23301da177e4SLinus Torvalds 23312e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 23325590ff0dSUlrich Drepper { 23335590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 23345590ff0dSUlrich Drepper return -EINVAL; 23355590ff0dSUlrich Drepper 23365590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 23375590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 23385590ff0dSUlrich Drepper 23395590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 23405590ff0dSUlrich Drepper } 23415590ff0dSUlrich Drepper 23423480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 23435590ff0dSUlrich Drepper { 23445590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 23455590ff0dSUlrich Drepper } 23465590ff0dSUlrich Drepper 2347db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 23481da177e4SLinus Torvalds { 2349a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 23501da177e4SLinus Torvalds 23511da177e4SLinus Torvalds if (error) 23521da177e4SLinus Torvalds return error; 23531da177e4SLinus Torvalds 2354acfa4380SAl Viro if (!dir->i_op->symlink) 23551da177e4SLinus Torvalds return -EPERM; 23561da177e4SLinus Torvalds 23571da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 23581da177e4SLinus Torvalds if (error) 23591da177e4SLinus Torvalds return error; 23601da177e4SLinus Torvalds 23619e3509e2SJan Kara vfs_dq_init(dir); 23621da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2363a74574aaSStephen Smalley if (!error) 2364f38aa942SAmy Griffis fsnotify_create(dir, dentry); 23651da177e4SLinus Torvalds return error; 23661da177e4SLinus Torvalds } 23671da177e4SLinus Torvalds 23682e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 23692e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 23701da177e4SLinus Torvalds { 23712ad94ae6SAl Viro int error; 23721da177e4SLinus Torvalds char *from; 23731da177e4SLinus Torvalds char *to; 23746902d925SDave Hansen struct dentry *dentry; 23756902d925SDave Hansen struct nameidata nd; 23761da177e4SLinus Torvalds 23771da177e4SLinus Torvalds from = getname(oldname); 23781da177e4SLinus Torvalds if (IS_ERR(from)) 23791da177e4SLinus Torvalds return PTR_ERR(from); 23802ad94ae6SAl Viro 23812ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 23822ad94ae6SAl Viro if (error) 23836902d925SDave Hansen goto out_putname; 23841da177e4SLinus Torvalds 23851da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 23861da177e4SLinus Torvalds error = PTR_ERR(dentry); 23876902d925SDave Hansen if (IS_ERR(dentry)) 23886902d925SDave Hansen goto out_unlock; 23896902d925SDave Hansen 239075c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 239175c3f29dSDave Hansen if (error) 239275c3f29dSDave Hansen goto out_dput; 2393be6d3e56SKentaro Takeda error = security_path_symlink(&nd.path, dentry, from); 2394be6d3e56SKentaro Takeda if (error) 2395be6d3e56SKentaro Takeda goto out_drop_write; 2396db2e747bSMiklos Szeredi error = vfs_symlink(nd.path.dentry->d_inode, dentry, from); 2397be6d3e56SKentaro Takeda out_drop_write: 239875c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 239975c3f29dSDave Hansen out_dput: 24001da177e4SLinus Torvalds dput(dentry); 24016902d925SDave Hansen out_unlock: 24024ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 24031d957f9bSJan Blunck path_put(&nd.path); 24041da177e4SLinus Torvalds putname(to); 24056902d925SDave Hansen out_putname: 24061da177e4SLinus Torvalds putname(from); 24071da177e4SLinus Torvalds return error; 24081da177e4SLinus Torvalds } 24091da177e4SLinus Torvalds 24103480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 24115590ff0dSUlrich Drepper { 24125590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 24135590ff0dSUlrich Drepper } 24145590ff0dSUlrich Drepper 24151da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 24161da177e4SLinus Torvalds { 24171da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 24181da177e4SLinus Torvalds int error; 24191da177e4SLinus Torvalds 24201da177e4SLinus Torvalds if (!inode) 24211da177e4SLinus Torvalds return -ENOENT; 24221da177e4SLinus Torvalds 2423a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 24241da177e4SLinus Torvalds if (error) 24251da177e4SLinus Torvalds return error; 24261da177e4SLinus Torvalds 24271da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 24281da177e4SLinus Torvalds return -EXDEV; 24291da177e4SLinus Torvalds 24301da177e4SLinus Torvalds /* 24311da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 24321da177e4SLinus Torvalds */ 24331da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 24341da177e4SLinus Torvalds return -EPERM; 2435acfa4380SAl Viro if (!dir->i_op->link) 24361da177e4SLinus Torvalds return -EPERM; 24377e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 24381da177e4SLinus Torvalds return -EPERM; 24391da177e4SLinus Torvalds 24401da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 24411da177e4SLinus Torvalds if (error) 24421da177e4SLinus Torvalds return error; 24431da177e4SLinus Torvalds 24447e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 24459e3509e2SJan Kara vfs_dq_init(dir); 24461da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 24477e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 2448e31e14ecSStephen Smalley if (!error) 24497e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 24501da177e4SLinus Torvalds return error; 24511da177e4SLinus Torvalds } 24521da177e4SLinus Torvalds 24531da177e4SLinus Torvalds /* 24541da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 24551da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 24561da177e4SLinus Torvalds * newname. --KAB 24571da177e4SLinus Torvalds * 24581da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 24591da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 24601da177e4SLinus Torvalds * and other special files. --ADM 24611da177e4SLinus Torvalds */ 24622e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 24632e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 24641da177e4SLinus Torvalds { 24651da177e4SLinus Torvalds struct dentry *new_dentry; 24662d8f3038SAl Viro struct nameidata nd; 24672d8f3038SAl Viro struct path old_path; 24681da177e4SLinus Torvalds int error; 24691da177e4SLinus Torvalds char *to; 24701da177e4SLinus Torvalds 247145c9b11aSUlrich Drepper if ((flags & ~AT_SYMLINK_FOLLOW) != 0) 2472c04030e1SUlrich Drepper return -EINVAL; 2473c04030e1SUlrich Drepper 24742d8f3038SAl Viro error = user_path_at(olddfd, oldname, 247545c9b11aSUlrich Drepper flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0, 24762d8f3038SAl Viro &old_path); 24771da177e4SLinus Torvalds if (error) 24782ad94ae6SAl Viro return error; 24792ad94ae6SAl Viro 24802ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 24811da177e4SLinus Torvalds if (error) 24821da177e4SLinus Torvalds goto out; 24831da177e4SLinus Torvalds error = -EXDEV; 24842d8f3038SAl Viro if (old_path.mnt != nd.path.mnt) 24851da177e4SLinus Torvalds goto out_release; 24861da177e4SLinus Torvalds new_dentry = lookup_create(&nd, 0); 24871da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 24886902d925SDave Hansen if (IS_ERR(new_dentry)) 24896902d925SDave Hansen goto out_unlock; 249075c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 249175c3f29dSDave Hansen if (error) 249275c3f29dSDave Hansen goto out_dput; 2493be6d3e56SKentaro Takeda error = security_path_link(old_path.dentry, &nd.path, new_dentry); 2494be6d3e56SKentaro Takeda if (error) 2495be6d3e56SKentaro Takeda goto out_drop_write; 24962d8f3038SAl Viro error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry); 2497be6d3e56SKentaro Takeda out_drop_write: 249875c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 249975c3f29dSDave Hansen out_dput: 25001da177e4SLinus Torvalds dput(new_dentry); 25016902d925SDave Hansen out_unlock: 25024ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 25031da177e4SLinus Torvalds out_release: 25041d957f9bSJan Blunck path_put(&nd.path); 25052ad94ae6SAl Viro putname(to); 25061da177e4SLinus Torvalds out: 25072d8f3038SAl Viro path_put(&old_path); 25081da177e4SLinus Torvalds 25091da177e4SLinus Torvalds return error; 25101da177e4SLinus Torvalds } 25111da177e4SLinus Torvalds 25123480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 25135590ff0dSUlrich Drepper { 2514c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 25155590ff0dSUlrich Drepper } 25165590ff0dSUlrich Drepper 25171da177e4SLinus Torvalds /* 25181da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 25191da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 25201da177e4SLinus Torvalds * Problems: 25211da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 25221da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 25231da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 2524a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 25251da177e4SLinus Torvalds * story. 25261da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 25271b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 25281da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 25291da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 2530a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 25311da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 25321da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 25331da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 2534a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 25351da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 25361da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 25371da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 25381da177e4SLinus Torvalds * d) some filesystems don't support opened-but-unlinked directories, 25391da177e4SLinus Torvalds * either because of layout or because they are not ready to deal with 25401da177e4SLinus Torvalds * all cases correctly. The latter will be fixed (taking this sort of 25411da177e4SLinus Torvalds * stuff into VFS), but the former is not going away. Solution: the same 25421da177e4SLinus Torvalds * trick as in rmdir(). 25431da177e4SLinus Torvalds * e) conversion from fhandle to dentry may come in the wrong moment - when 25441b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 25451da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 25461b1dcc1bSJes Sorensen * ->i_mutex on parents, which works but leads to some truely excessive 25471da177e4SLinus Torvalds * locking]. 25481da177e4SLinus Torvalds */ 254975c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 25501da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 25511da177e4SLinus Torvalds { 25521da177e4SLinus Torvalds int error = 0; 25531da177e4SLinus Torvalds struct inode *target; 25541da177e4SLinus Torvalds 25551da177e4SLinus Torvalds /* 25561da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 25571da177e4SLinus Torvalds * we'll need to flip '..'. 25581da177e4SLinus Torvalds */ 25591da177e4SLinus Torvalds if (new_dir != old_dir) { 2560f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 25611da177e4SLinus Torvalds if (error) 25621da177e4SLinus Torvalds return error; 25631da177e4SLinus Torvalds } 25641da177e4SLinus Torvalds 25651da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 25661da177e4SLinus Torvalds if (error) 25671da177e4SLinus Torvalds return error; 25681da177e4SLinus Torvalds 25691da177e4SLinus Torvalds target = new_dentry->d_inode; 25701da177e4SLinus Torvalds if (target) { 25711b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 25721da177e4SLinus Torvalds dentry_unhash(new_dentry); 25731da177e4SLinus Torvalds } 25741da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 25751da177e4SLinus Torvalds error = -EBUSY; 25761da177e4SLinus Torvalds else 25771da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 25781da177e4SLinus Torvalds if (target) { 25791da177e4SLinus Torvalds if (!error) 25801da177e4SLinus Torvalds target->i_flags |= S_DEAD; 25811b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 25821da177e4SLinus Torvalds if (d_unhashed(new_dentry)) 25831da177e4SLinus Torvalds d_rehash(new_dentry); 25841da177e4SLinus Torvalds dput(new_dentry); 25851da177e4SLinus Torvalds } 2586e31e14ecSStephen Smalley if (!error) 2587349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 25881da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 25891da177e4SLinus Torvalds return error; 25901da177e4SLinus Torvalds } 25911da177e4SLinus Torvalds 259275c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 25931da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 25941da177e4SLinus Torvalds { 25951da177e4SLinus Torvalds struct inode *target; 25961da177e4SLinus Torvalds int error; 25971da177e4SLinus Torvalds 25981da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 25991da177e4SLinus Torvalds if (error) 26001da177e4SLinus Torvalds return error; 26011da177e4SLinus Torvalds 26021da177e4SLinus Torvalds dget(new_dentry); 26031da177e4SLinus Torvalds target = new_dentry->d_inode; 26041da177e4SLinus Torvalds if (target) 26051b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 26061da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 26071da177e4SLinus Torvalds error = -EBUSY; 26081da177e4SLinus Torvalds else 26091da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 26101da177e4SLinus Torvalds if (!error) { 2611349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 26121da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 26131da177e4SLinus Torvalds } 26141da177e4SLinus Torvalds if (target) 26151b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 26161da177e4SLinus Torvalds dput(new_dentry); 26171da177e4SLinus Torvalds return error; 26181da177e4SLinus Torvalds } 26191da177e4SLinus Torvalds 26201da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 26211da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 26221da177e4SLinus Torvalds { 26231da177e4SLinus Torvalds int error; 26241da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 26250eeca283SRobert Love const char *old_name; 26261da177e4SLinus Torvalds 26271da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 26281da177e4SLinus Torvalds return 0; 26291da177e4SLinus Torvalds 26301da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 26311da177e4SLinus Torvalds if (error) 26321da177e4SLinus Torvalds return error; 26331da177e4SLinus Torvalds 26341da177e4SLinus Torvalds if (!new_dentry->d_inode) 2635a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 26361da177e4SLinus Torvalds else 26371da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 26381da177e4SLinus Torvalds if (error) 26391da177e4SLinus Torvalds return error; 26401da177e4SLinus Torvalds 2641acfa4380SAl Viro if (!old_dir->i_op->rename) 26421da177e4SLinus Torvalds return -EPERM; 26431da177e4SLinus Torvalds 26449e3509e2SJan Kara vfs_dq_init(old_dir); 26459e3509e2SJan Kara vfs_dq_init(new_dir); 26461da177e4SLinus Torvalds 26470eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 26480eeca283SRobert Love 26491da177e4SLinus Torvalds if (is_dir) 26501da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 26511da177e4SLinus Torvalds else 26521da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 26531da177e4SLinus Torvalds if (!error) { 26540eeca283SRobert Love const char *new_name = old_dentry->d_name.name; 265589204c40SJohn McCutchan fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir, 26565a190ae6SAl Viro new_dentry->d_inode, old_dentry); 26571da177e4SLinus Torvalds } 26580eeca283SRobert Love fsnotify_oldname_free(old_name); 26590eeca283SRobert Love 26601da177e4SLinus Torvalds return error; 26611da177e4SLinus Torvalds } 26621da177e4SLinus Torvalds 26632e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 26642e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 26651da177e4SLinus Torvalds { 26661da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 26671da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 26681da177e4SLinus Torvalds struct dentry *trap; 26691da177e4SLinus Torvalds struct nameidata oldnd, newnd; 26702ad94ae6SAl Viro char *from; 26712ad94ae6SAl Viro char *to; 26722ad94ae6SAl Viro int error; 26731da177e4SLinus Torvalds 26742ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 26751da177e4SLinus Torvalds if (error) 26761da177e4SLinus Torvalds goto exit; 26771da177e4SLinus Torvalds 26782ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 26791da177e4SLinus Torvalds if (error) 26801da177e4SLinus Torvalds goto exit1; 26811da177e4SLinus Torvalds 26821da177e4SLinus Torvalds error = -EXDEV; 26834ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 26841da177e4SLinus Torvalds goto exit2; 26851da177e4SLinus Torvalds 26864ac91378SJan Blunck old_dir = oldnd.path.dentry; 26871da177e4SLinus Torvalds error = -EBUSY; 26881da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 26891da177e4SLinus Torvalds goto exit2; 26901da177e4SLinus Torvalds 26914ac91378SJan Blunck new_dir = newnd.path.dentry; 26921da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 26931da177e4SLinus Torvalds goto exit2; 26941da177e4SLinus Torvalds 26950612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 26960612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 26974e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 26980612d9fbSOGAWA Hirofumi 26991da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 27001da177e4SLinus Torvalds 270149705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 27021da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 27031da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 27041da177e4SLinus Torvalds goto exit3; 27051da177e4SLinus Torvalds /* source must exist */ 27061da177e4SLinus Torvalds error = -ENOENT; 27071da177e4SLinus Torvalds if (!old_dentry->d_inode) 27081da177e4SLinus Torvalds goto exit4; 27091da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 27101da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 27111da177e4SLinus Torvalds error = -ENOTDIR; 27121da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 27131da177e4SLinus Torvalds goto exit4; 27141da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 27151da177e4SLinus Torvalds goto exit4; 27161da177e4SLinus Torvalds } 27171da177e4SLinus Torvalds /* source should not be ancestor of target */ 27181da177e4SLinus Torvalds error = -EINVAL; 27191da177e4SLinus Torvalds if (old_dentry == trap) 27201da177e4SLinus Torvalds goto exit4; 272149705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 27221da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 27231da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 27241da177e4SLinus Torvalds goto exit4; 27251da177e4SLinus Torvalds /* target should not be an ancestor of source */ 27261da177e4SLinus Torvalds error = -ENOTEMPTY; 27271da177e4SLinus Torvalds if (new_dentry == trap) 27281da177e4SLinus Torvalds goto exit5; 27291da177e4SLinus Torvalds 27309079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 27319079b1ebSDave Hansen if (error) 27329079b1ebSDave Hansen goto exit5; 2733be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 2734be6d3e56SKentaro Takeda &newnd.path, new_dentry); 2735be6d3e56SKentaro Takeda if (error) 2736be6d3e56SKentaro Takeda goto exit6; 27371da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 27381da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 2739be6d3e56SKentaro Takeda exit6: 27409079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 27411da177e4SLinus Torvalds exit5: 27421da177e4SLinus Torvalds dput(new_dentry); 27431da177e4SLinus Torvalds exit4: 27441da177e4SLinus Torvalds dput(old_dentry); 27451da177e4SLinus Torvalds exit3: 27461da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 27471da177e4SLinus Torvalds exit2: 27481d957f9bSJan Blunck path_put(&newnd.path); 27492ad94ae6SAl Viro putname(to); 27501da177e4SLinus Torvalds exit1: 27511d957f9bSJan Blunck path_put(&oldnd.path); 27521da177e4SLinus Torvalds putname(from); 27532ad94ae6SAl Viro exit: 27541da177e4SLinus Torvalds return error; 27551da177e4SLinus Torvalds } 27561da177e4SLinus Torvalds 2757a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 27585590ff0dSUlrich Drepper { 27595590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 27605590ff0dSUlrich Drepper } 27615590ff0dSUlrich Drepper 27621da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 27631da177e4SLinus Torvalds { 27641da177e4SLinus Torvalds int len; 27651da177e4SLinus Torvalds 27661da177e4SLinus Torvalds len = PTR_ERR(link); 27671da177e4SLinus Torvalds if (IS_ERR(link)) 27681da177e4SLinus Torvalds goto out; 27691da177e4SLinus Torvalds 27701da177e4SLinus Torvalds len = strlen(link); 27711da177e4SLinus Torvalds if (len > (unsigned) buflen) 27721da177e4SLinus Torvalds len = buflen; 27731da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 27741da177e4SLinus Torvalds len = -EFAULT; 27751da177e4SLinus Torvalds out: 27761da177e4SLinus Torvalds return len; 27771da177e4SLinus Torvalds } 27781da177e4SLinus Torvalds 27791da177e4SLinus Torvalds /* 27801da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 27811da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 27821da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 27831da177e4SLinus Torvalds */ 27841da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 27851da177e4SLinus Torvalds { 27861da177e4SLinus Torvalds struct nameidata nd; 2787cc314eefSLinus Torvalds void *cookie; 2788694a1764SMarcin Slusarz int res; 2789cc314eefSLinus Torvalds 27901da177e4SLinus Torvalds nd.depth = 0; 2791cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 2792694a1764SMarcin Slusarz if (IS_ERR(cookie)) 2793694a1764SMarcin Slusarz return PTR_ERR(cookie); 2794694a1764SMarcin Slusarz 2795694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 27961da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 2797cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 2798694a1764SMarcin Slusarz return res; 27991da177e4SLinus Torvalds } 28001da177e4SLinus Torvalds 28011da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 28021da177e4SLinus Torvalds { 28031da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 28041da177e4SLinus Torvalds } 28051da177e4SLinus Torvalds 28061da177e4SLinus Torvalds /* get the link contents into pagecache */ 28071da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 28081da177e4SLinus Torvalds { 2809ebd09abbSDuane Griffin char *kaddr; 28101da177e4SLinus Torvalds struct page *page; 28111da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 2812090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 28131da177e4SLinus Torvalds if (IS_ERR(page)) 28146fe6900eSNick Piggin return (char*)page; 28151da177e4SLinus Torvalds *ppage = page; 2816ebd09abbSDuane Griffin kaddr = kmap(page); 2817ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 2818ebd09abbSDuane Griffin return kaddr; 28191da177e4SLinus Torvalds } 28201da177e4SLinus Torvalds 28211da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 28221da177e4SLinus Torvalds { 28231da177e4SLinus Torvalds struct page *page = NULL; 28241da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 28251da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 28261da177e4SLinus Torvalds if (page) { 28271da177e4SLinus Torvalds kunmap(page); 28281da177e4SLinus Torvalds page_cache_release(page); 28291da177e4SLinus Torvalds } 28301da177e4SLinus Torvalds return res; 28311da177e4SLinus Torvalds } 28321da177e4SLinus Torvalds 2833cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 28341da177e4SLinus Torvalds { 2835cc314eefSLinus Torvalds struct page *page = NULL; 28361da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 2837cc314eefSLinus Torvalds return page; 28381da177e4SLinus Torvalds } 28391da177e4SLinus Torvalds 2840cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 28411da177e4SLinus Torvalds { 2842cc314eefSLinus Torvalds struct page *page = cookie; 2843cc314eefSLinus Torvalds 2844cc314eefSLinus Torvalds if (page) { 28451da177e4SLinus Torvalds kunmap(page); 28461da177e4SLinus Torvalds page_cache_release(page); 28471da177e4SLinus Torvalds } 28481da177e4SLinus Torvalds } 28491da177e4SLinus Torvalds 285054566b2cSNick Piggin /* 285154566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 285254566b2cSNick Piggin */ 285354566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 28541da177e4SLinus Torvalds { 28551da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 28560adb25d2SKirill Korotaev struct page *page; 2857afddba49SNick Piggin void *fsdata; 2858beb497abSDmitriy Monakhov int err; 28591da177e4SLinus Torvalds char *kaddr; 286054566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 286154566b2cSNick Piggin if (nofs) 286254566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 28631da177e4SLinus Torvalds 28647e53cac4SNeilBrown retry: 2865afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 286654566b2cSNick Piggin flags, &page, &fsdata); 28671da177e4SLinus Torvalds if (err) 2868afddba49SNick Piggin goto fail; 2869afddba49SNick Piggin 28701da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 28711da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 28721da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 2873afddba49SNick Piggin 2874afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 2875afddba49SNick Piggin page, fsdata); 28761da177e4SLinus Torvalds if (err < 0) 28771da177e4SLinus Torvalds goto fail; 2878afddba49SNick Piggin if (err < len-1) 2879afddba49SNick Piggin goto retry; 2880afddba49SNick Piggin 28811da177e4SLinus Torvalds mark_inode_dirty(inode); 28821da177e4SLinus Torvalds return 0; 28831da177e4SLinus Torvalds fail: 28841da177e4SLinus Torvalds return err; 28851da177e4SLinus Torvalds } 28861da177e4SLinus Torvalds 28870adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 28880adb25d2SKirill Korotaev { 28890adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 289054566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 28910adb25d2SKirill Korotaev } 28920adb25d2SKirill Korotaev 289392e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 28941da177e4SLinus Torvalds .readlink = generic_readlink, 28951da177e4SLinus Torvalds .follow_link = page_follow_link_light, 28961da177e4SLinus Torvalds .put_link = page_put_link, 28971da177e4SLinus Torvalds }; 28981da177e4SLinus Torvalds 28992d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 29001da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 29011da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 29021da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 29031da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 29041da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 29051da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 29061da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 29071da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 29081da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 29090adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 29101da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 29111da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 29121da177e4SLinus Torvalds EXPORT_SYMBOL(path_lookup); 2913d1811465SAl Viro EXPORT_SYMBOL(kern_path); 291416f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 2915f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 29168c744fb8SChristoph Hellwig EXPORT_SYMBOL(file_permission); 29171da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 29181da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 29191da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 29201da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 29211da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 29221da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 29231da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 29241da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 29251da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 29261da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 29271da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 29281da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 29291da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 29301da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 2931