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 1725909ccaaSLinus Torvalds /* 1735909ccaaSLinus Torvalds * This does basic POSIX ACL permission checking 1745909ccaaSLinus Torvalds */ 1755909ccaaSLinus Torvalds static int acl_permission_check(struct inode *inode, int mask, 1765909ccaaSLinus Torvalds int (*check_acl)(struct inode *inode, int mask)) 1775909ccaaSLinus Torvalds { 1785909ccaaSLinus Torvalds umode_t mode = inode->i_mode; 1795909ccaaSLinus Torvalds 1805909ccaaSLinus Torvalds mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 1815909ccaaSLinus Torvalds 1825909ccaaSLinus Torvalds if (current_fsuid() == inode->i_uid) 1835909ccaaSLinus Torvalds mode >>= 6; 1845909ccaaSLinus Torvalds else { 1855909ccaaSLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) { 1865909ccaaSLinus Torvalds int error = check_acl(inode, mask); 1875909ccaaSLinus Torvalds if (error != -EAGAIN) 1885909ccaaSLinus Torvalds return error; 1895909ccaaSLinus Torvalds } 1905909ccaaSLinus Torvalds 1915909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 1925909ccaaSLinus Torvalds mode >>= 3; 1935909ccaaSLinus Torvalds } 1945909ccaaSLinus Torvalds 1955909ccaaSLinus Torvalds /* 1965909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 1975909ccaaSLinus Torvalds */ 1985909ccaaSLinus Torvalds if ((mask & ~mode) == 0) 1995909ccaaSLinus Torvalds return 0; 2005909ccaaSLinus Torvalds return -EACCES; 2015909ccaaSLinus Torvalds } 2021da177e4SLinus Torvalds 2031da177e4SLinus Torvalds /** 2041da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 2051da177e4SLinus Torvalds * @inode: inode to check access rights for 2061da177e4SLinus Torvalds * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 2071da177e4SLinus Torvalds * @check_acl: optional callback to check for Posix ACLs 2081da177e4SLinus Torvalds * 2091da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 2101da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 2111da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 2121da177e4SLinus Torvalds * are used for other things.. 2131da177e4SLinus Torvalds */ 2141da177e4SLinus Torvalds int generic_permission(struct inode *inode, int mask, 2151da177e4SLinus Torvalds int (*check_acl)(struct inode *inode, int mask)) 2161da177e4SLinus Torvalds { 2175909ccaaSLinus Torvalds int ret; 2181da177e4SLinus Torvalds 2191da177e4SLinus Torvalds /* 2205909ccaaSLinus Torvalds * Do the basic POSIX ACL permission checks. 2211da177e4SLinus Torvalds */ 2225909ccaaSLinus Torvalds ret = acl_permission_check(inode, mask, check_acl); 2235909ccaaSLinus Torvalds if (ret != -EACCES) 2245909ccaaSLinus Torvalds return ret; 2251da177e4SLinus Torvalds 2261da177e4SLinus Torvalds /* 2271da177e4SLinus Torvalds * Read/write DACs are always overridable. 2281da177e4SLinus Torvalds * Executable DACs are overridable if at least one exec bit is set. 2291da177e4SLinus Torvalds */ 230f696a365SMiklos Szeredi if (!(mask & MAY_EXEC) || execute_ok(inode)) 2311da177e4SLinus Torvalds if (capable(CAP_DAC_OVERRIDE)) 2321da177e4SLinus Torvalds return 0; 2331da177e4SLinus Torvalds 2341da177e4SLinus Torvalds /* 2351da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 2361da177e4SLinus Torvalds */ 2371da177e4SLinus Torvalds if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))) 2381da177e4SLinus Torvalds if (capable(CAP_DAC_READ_SEARCH)) 2391da177e4SLinus Torvalds return 0; 2401da177e4SLinus Torvalds 2411da177e4SLinus Torvalds return -EACCES; 2421da177e4SLinus Torvalds } 2431da177e4SLinus Torvalds 244cb23beb5SChristoph Hellwig /** 245cb23beb5SChristoph Hellwig * inode_permission - check for access rights to a given inode 246cb23beb5SChristoph Hellwig * @inode: inode to check permission on 247cb23beb5SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 248cb23beb5SChristoph Hellwig * 249cb23beb5SChristoph Hellwig * Used to check for read/write/execute permissions on an inode. 250cb23beb5SChristoph Hellwig * We use "fsuid" for this, letting us set arbitrary permissions 251cb23beb5SChristoph Hellwig * for filesystem access without changing the "normal" uids which 252cb23beb5SChristoph Hellwig * are used for other things. 253cb23beb5SChristoph Hellwig */ 254f419a2e3SAl Viro int inode_permission(struct inode *inode, int mask) 2551da177e4SLinus Torvalds { 256e6305c43SAl Viro int retval; 2571da177e4SLinus Torvalds 2581da177e4SLinus Torvalds if (mask & MAY_WRITE) { 25922590e41SMiklos Szeredi umode_t mode = inode->i_mode; 2601da177e4SLinus Torvalds 2611da177e4SLinus Torvalds /* 2621da177e4SLinus Torvalds * Nobody gets write access to a read-only fs. 2631da177e4SLinus Torvalds */ 2641da177e4SLinus Torvalds if (IS_RDONLY(inode) && 2651da177e4SLinus Torvalds (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 2661da177e4SLinus Torvalds return -EROFS; 2671da177e4SLinus Torvalds 2681da177e4SLinus Torvalds /* 2691da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 2701da177e4SLinus Torvalds */ 2711da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 2721da177e4SLinus Torvalds return -EACCES; 2731da177e4SLinus Torvalds } 2741da177e4SLinus Torvalds 275acfa4380SAl Viro if (inode->i_op->permission) 276b77b0646SAl Viro retval = inode->i_op->permission(inode, mask); 277f696a365SMiklos Szeredi else 2785909ccaaSLinus Torvalds retval = generic_permission(inode, mask, inode->i_op->check_acl); 279f696a365SMiklos Szeredi 2801da177e4SLinus Torvalds if (retval) 2811da177e4SLinus Torvalds return retval; 2821da177e4SLinus Torvalds 28308ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 28408ce5f16SSerge E. Hallyn if (retval) 28508ce5f16SSerge E. Hallyn return retval; 28608ce5f16SSerge E. Hallyn 287e6305c43SAl Viro return security_inode_permission(inode, 288f418b006SStephen Smalley mask & (MAY_READ|MAY_WRITE|MAY_EXEC|MAY_APPEND)); 2891da177e4SLinus Torvalds } 2901da177e4SLinus Torvalds 291e4543eddSChristoph Hellwig /** 2928c744fb8SChristoph Hellwig * file_permission - check for additional access rights to a given file 2938c744fb8SChristoph Hellwig * @file: file to check access rights for 2948c744fb8SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 2958c744fb8SChristoph Hellwig * 2968c744fb8SChristoph Hellwig * Used to check for read/write/execute permissions on an already opened 2978c744fb8SChristoph Hellwig * file. 2988c744fb8SChristoph Hellwig * 2998c744fb8SChristoph Hellwig * Note: 3008c744fb8SChristoph Hellwig * Do not use this function in new code. All access checks should 301cb23beb5SChristoph Hellwig * be done using inode_permission(). 3028c744fb8SChristoph Hellwig */ 3038c744fb8SChristoph Hellwig int file_permission(struct file *file, int mask) 3048c744fb8SChristoph Hellwig { 305f419a2e3SAl Viro return inode_permission(file->f_path.dentry->d_inode, mask); 3068c744fb8SChristoph Hellwig } 3078c744fb8SChristoph Hellwig 3081da177e4SLinus Torvalds /* 3091da177e4SLinus Torvalds * get_write_access() gets write permission for a file. 3101da177e4SLinus Torvalds * put_write_access() releases this write permission. 3111da177e4SLinus Torvalds * This is used for regular files. 3121da177e4SLinus Torvalds * We cannot support write (and maybe mmap read-write shared) accesses and 3131da177e4SLinus Torvalds * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode 3141da177e4SLinus Torvalds * can have the following values: 3151da177e4SLinus Torvalds * 0: no writers, no VM_DENYWRITE mappings 3161da177e4SLinus Torvalds * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist 3171da177e4SLinus Torvalds * > 0: (i_writecount) users are writing to the file. 3181da177e4SLinus Torvalds * 3191da177e4SLinus Torvalds * Normally we operate on that counter with atomic_{inc,dec} and it's safe 3201da177e4SLinus Torvalds * except for the cases where we don't hold i_writecount yet. Then we need to 3211da177e4SLinus Torvalds * use {get,deny}_write_access() - these functions check the sign and refuse 3221da177e4SLinus Torvalds * to do the change if sign is wrong. Exclusion between them is provided by 3231da177e4SLinus Torvalds * the inode->i_lock spinlock. 3241da177e4SLinus Torvalds */ 3251da177e4SLinus Torvalds 3261da177e4SLinus Torvalds int get_write_access(struct inode * inode) 3271da177e4SLinus Torvalds { 3281da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3291da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) < 0) { 3301da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3311da177e4SLinus Torvalds return -ETXTBSY; 3321da177e4SLinus Torvalds } 3331da177e4SLinus Torvalds atomic_inc(&inode->i_writecount); 3341da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3351da177e4SLinus Torvalds 3361da177e4SLinus Torvalds return 0; 3371da177e4SLinus Torvalds } 3381da177e4SLinus Torvalds 3391da177e4SLinus Torvalds int deny_write_access(struct file * file) 3401da177e4SLinus Torvalds { 3410f7fc9e4SJosef "Jeff" Sipek struct inode *inode = file->f_path.dentry->d_inode; 3421da177e4SLinus Torvalds 3431da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3441da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) > 0) { 3451da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3461da177e4SLinus Torvalds return -ETXTBSY; 3471da177e4SLinus Torvalds } 3481da177e4SLinus Torvalds atomic_dec(&inode->i_writecount); 3491da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3501da177e4SLinus Torvalds 3511da177e4SLinus Torvalds return 0; 3521da177e4SLinus Torvalds } 3531da177e4SLinus Torvalds 3541d957f9bSJan Blunck /** 3555dd784d0SJan Blunck * path_get - get a reference to a path 3565dd784d0SJan Blunck * @path: path to get the reference to 3575dd784d0SJan Blunck * 3585dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 3595dd784d0SJan Blunck */ 3605dd784d0SJan Blunck void path_get(struct path *path) 3615dd784d0SJan Blunck { 3625dd784d0SJan Blunck mntget(path->mnt); 3635dd784d0SJan Blunck dget(path->dentry); 3645dd784d0SJan Blunck } 3655dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 3665dd784d0SJan Blunck 3675dd784d0SJan Blunck /** 3681d957f9bSJan Blunck * path_put - put a reference to a path 3691d957f9bSJan Blunck * @path: path to put the reference to 3701d957f9bSJan Blunck * 3711d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 3721d957f9bSJan Blunck */ 3731d957f9bSJan Blunck void path_put(struct path *path) 3741da177e4SLinus Torvalds { 3751d957f9bSJan Blunck dput(path->dentry); 3761d957f9bSJan Blunck mntput(path->mnt); 3771da177e4SLinus Torvalds } 3781d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 3791da177e4SLinus Torvalds 380834f2a4aSTrond Myklebust /** 381834f2a4aSTrond Myklebust * release_open_intent - free up open intent resources 382834f2a4aSTrond Myklebust * @nd: pointer to nameidata 383834f2a4aSTrond Myklebust */ 384834f2a4aSTrond Myklebust void release_open_intent(struct nameidata *nd) 385834f2a4aSTrond Myklebust { 3860f7fc9e4SJosef "Jeff" Sipek if (nd->intent.open.file->f_path.dentry == NULL) 387834f2a4aSTrond Myklebust put_filp(nd->intent.open.file); 388834f2a4aSTrond Myklebust else 389834f2a4aSTrond Myklebust fput(nd->intent.open.file); 390834f2a4aSTrond Myklebust } 391834f2a4aSTrond Myklebust 392bcdc5e01SIan Kent static inline struct dentry * 393bcdc5e01SIan Kent do_revalidate(struct dentry *dentry, struct nameidata *nd) 394bcdc5e01SIan Kent { 395bcdc5e01SIan Kent int status = dentry->d_op->d_revalidate(dentry, nd); 396bcdc5e01SIan Kent if (unlikely(status <= 0)) { 397bcdc5e01SIan Kent /* 398bcdc5e01SIan Kent * The dentry failed validation. 399bcdc5e01SIan Kent * If d_revalidate returned 0 attempt to invalidate 400bcdc5e01SIan Kent * the dentry otherwise d_revalidate is asking us 401bcdc5e01SIan Kent * to return a fail status. 402bcdc5e01SIan Kent */ 403bcdc5e01SIan Kent if (!status) { 404bcdc5e01SIan Kent if (!d_invalidate(dentry)) { 405bcdc5e01SIan Kent dput(dentry); 406bcdc5e01SIan Kent dentry = NULL; 407bcdc5e01SIan Kent } 408bcdc5e01SIan Kent } else { 409bcdc5e01SIan Kent dput(dentry); 410bcdc5e01SIan Kent dentry = ERR_PTR(status); 411bcdc5e01SIan Kent } 412bcdc5e01SIan Kent } 413bcdc5e01SIan Kent return dentry; 414bcdc5e01SIan Kent } 415bcdc5e01SIan Kent 4161da177e4SLinus Torvalds /* 4171da177e4SLinus Torvalds * Internal lookup() using the new generic dcache. 4181da177e4SLinus Torvalds * SMP-safe 4191da177e4SLinus Torvalds */ 4201da177e4SLinus Torvalds static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) 4211da177e4SLinus Torvalds { 4221da177e4SLinus Torvalds struct dentry * dentry = __d_lookup(parent, name); 4231da177e4SLinus Torvalds 4241da177e4SLinus Torvalds /* lockess __d_lookup may fail due to concurrent d_move() 4251da177e4SLinus Torvalds * in some unrelated directory, so try with d_lookup 4261da177e4SLinus Torvalds */ 4271da177e4SLinus Torvalds if (!dentry) 4281da177e4SLinus Torvalds dentry = d_lookup(parent, name); 4291da177e4SLinus Torvalds 430bcdc5e01SIan Kent if (dentry && dentry->d_op && dentry->d_op->d_revalidate) 431bcdc5e01SIan Kent dentry = do_revalidate(dentry, nd); 432bcdc5e01SIan Kent 4331da177e4SLinus Torvalds return dentry; 4341da177e4SLinus Torvalds } 4351da177e4SLinus Torvalds 4361da177e4SLinus Torvalds /* 4371da177e4SLinus Torvalds * Short-cut version of permission(), for calling by 4381da177e4SLinus Torvalds * path_walk(), when dcache lock is held. Combines parts 4391da177e4SLinus Torvalds * of permission() and generic_permission(), and tests ONLY for 4401da177e4SLinus Torvalds * MAY_EXEC permission. 4411da177e4SLinus Torvalds * 4421da177e4SLinus Torvalds * If appropriate, check DAC only. If not appropriate, or 4431da177e4SLinus Torvalds * short-cut DAC fails, then call permission() to do more 4441da177e4SLinus Torvalds * complete permission check. 4451da177e4SLinus Torvalds */ 446672b16b2SAl Viro static int exec_permission_lite(struct inode *inode) 4471da177e4SLinus Torvalds { 4485909ccaaSLinus Torvalds int ret; 4491da177e4SLinus Torvalds 450cb9179eaSLinus Torvalds if (inode->i_op->permission) { 4515909ccaaSLinus Torvalds ret = inode->i_op->permission(inode, MAY_EXEC); 452cb9179eaSLinus Torvalds if (!ret) 453cb9179eaSLinus Torvalds goto ok; 454cb9179eaSLinus Torvalds return ret; 455cb9179eaSLinus Torvalds } 4565909ccaaSLinus Torvalds ret = acl_permission_check(inode, MAY_EXEC, inode->i_op->check_acl); 4575909ccaaSLinus Torvalds if (!ret) 4581da177e4SLinus Torvalds goto ok; 4591da177e4SLinus Torvalds 460f1ac9f6bSLinus Torvalds if (capable(CAP_DAC_OVERRIDE) || capable(CAP_DAC_READ_SEARCH)) 4611da177e4SLinus Torvalds goto ok; 4621da177e4SLinus Torvalds 4635909ccaaSLinus Torvalds return ret; 4641da177e4SLinus Torvalds ok: 465b77b0646SAl Viro return security_inode_permission(inode, MAY_EXEC); 4661da177e4SLinus Torvalds } 4671da177e4SLinus Torvalds 4681da177e4SLinus Torvalds /* 4691da177e4SLinus Torvalds * This is called when everything else fails, and we actually have 4701da177e4SLinus Torvalds * to go to the low-level filesystem to find out what we should do.. 4711da177e4SLinus Torvalds * 4721da177e4SLinus Torvalds * We get the directory semaphore, and after getting that we also 4731da177e4SLinus Torvalds * make sure that nobody added the entry to the dcache in the meantime.. 4741da177e4SLinus Torvalds * SMP-safe 4751da177e4SLinus Torvalds */ 4761da177e4SLinus Torvalds static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) 4771da177e4SLinus Torvalds { 4781da177e4SLinus Torvalds struct dentry * result; 4791da177e4SLinus Torvalds struct inode *dir = parent->d_inode; 4801da177e4SLinus Torvalds 4811b1dcc1bSJes Sorensen mutex_lock(&dir->i_mutex); 4821da177e4SLinus Torvalds /* 4831da177e4SLinus Torvalds * First re-do the cached lookup just in case it was created 4841da177e4SLinus Torvalds * while we waited for the directory semaphore.. 4851da177e4SLinus Torvalds * 4861da177e4SLinus Torvalds * FIXME! This could use version numbering or similar to 4871da177e4SLinus Torvalds * avoid unnecessary cache lookups. 4881da177e4SLinus Torvalds * 4891da177e4SLinus Torvalds * The "dcache_lock" is purely to protect the RCU list walker 4901da177e4SLinus Torvalds * from concurrent renames at this point (we mustn't get false 4911da177e4SLinus Torvalds * negatives from the RCU list walk here, unlike the optimistic 4921da177e4SLinus Torvalds * fast walk). 4931da177e4SLinus Torvalds * 4941da177e4SLinus Torvalds * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup 4951da177e4SLinus Torvalds */ 4961da177e4SLinus Torvalds result = d_lookup(parent, name); 4971da177e4SLinus Torvalds if (!result) { 498d70b67c8SMiklos Szeredi struct dentry *dentry; 499d70b67c8SMiklos Szeredi 500d70b67c8SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 501d70b67c8SMiklos Szeredi result = ERR_PTR(-ENOENT); 502d70b67c8SMiklos Szeredi if (IS_DEADDIR(dir)) 503d70b67c8SMiklos Szeredi goto out_unlock; 504d70b67c8SMiklos Szeredi 505d70b67c8SMiklos Szeredi dentry = d_alloc(parent, name); 5061da177e4SLinus Torvalds result = ERR_PTR(-ENOMEM); 5071da177e4SLinus Torvalds if (dentry) { 5081da177e4SLinus Torvalds result = dir->i_op->lookup(dir, dentry, nd); 5091da177e4SLinus Torvalds if (result) 5101da177e4SLinus Torvalds dput(dentry); 5111da177e4SLinus Torvalds else 5121da177e4SLinus Torvalds result = dentry; 5131da177e4SLinus Torvalds } 514d70b67c8SMiklos Szeredi out_unlock: 5151b1dcc1bSJes Sorensen mutex_unlock(&dir->i_mutex); 5161da177e4SLinus Torvalds return result; 5171da177e4SLinus Torvalds } 5181da177e4SLinus Torvalds 5191da177e4SLinus Torvalds /* 5201da177e4SLinus Torvalds * Uhhuh! Nasty case: the cache was re-populated while 5211da177e4SLinus Torvalds * we waited on the semaphore. Need to revalidate. 5221da177e4SLinus Torvalds */ 5231b1dcc1bSJes Sorensen mutex_unlock(&dir->i_mutex); 5241da177e4SLinus Torvalds if (result->d_op && result->d_op->d_revalidate) { 525bcdc5e01SIan Kent result = do_revalidate(result, nd); 526bcdc5e01SIan Kent if (!result) 5271da177e4SLinus Torvalds result = ERR_PTR(-ENOENT); 5281da177e4SLinus Torvalds } 5291da177e4SLinus Torvalds return result; 5301da177e4SLinus Torvalds } 5311da177e4SLinus Torvalds 532a02f76c3SAl Viro /* 533a02f76c3SAl Viro * Wrapper to retry pathname resolution whenever the underlying 534a02f76c3SAl Viro * file system returns an ESTALE. 535a02f76c3SAl Viro * 536a02f76c3SAl Viro * Retry the whole path once, forcing real lookup requests 537a02f76c3SAl Viro * instead of relying on the dcache. 538a02f76c3SAl Viro */ 539a02f76c3SAl Viro static __always_inline int link_path_walk(const char *name, struct nameidata *nd) 540a02f76c3SAl Viro { 541a02f76c3SAl Viro struct path save = nd->path; 542a02f76c3SAl Viro int result; 543a02f76c3SAl Viro 544a02f76c3SAl Viro /* make sure the stuff we saved doesn't go away */ 545c8e7f449SJan Blunck path_get(&save); 546a02f76c3SAl Viro 547a02f76c3SAl Viro result = __link_path_walk(name, nd); 548a02f76c3SAl Viro if (result == -ESTALE) { 549a02f76c3SAl Viro /* nd->path had been dropped */ 550a02f76c3SAl Viro nd->path = save; 551c8e7f449SJan Blunck path_get(&nd->path); 552a02f76c3SAl Viro nd->flags |= LOOKUP_REVAL; 553a02f76c3SAl Viro result = __link_path_walk(name, nd); 554a02f76c3SAl Viro } 555a02f76c3SAl Viro 556a02f76c3SAl Viro path_put(&save); 557a02f76c3SAl Viro 558a02f76c3SAl Viro return result; 559a02f76c3SAl Viro } 560a02f76c3SAl Viro 5612a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 5622a737871SAl Viro { 5632a737871SAl Viro if (!nd->root.mnt) { 5642a737871SAl Viro struct fs_struct *fs = current->fs; 5652a737871SAl Viro read_lock(&fs->lock); 5662a737871SAl Viro nd->root = fs->root; 5672a737871SAl Viro path_get(&nd->root); 5682a737871SAl Viro read_unlock(&fs->lock); 5692a737871SAl Viro } 5702a737871SAl Viro } 5712a737871SAl Viro 572f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 5731da177e4SLinus Torvalds { 5741da177e4SLinus Torvalds int res = 0; 5751da177e4SLinus Torvalds char *name; 5761da177e4SLinus Torvalds if (IS_ERR(link)) 5771da177e4SLinus Torvalds goto fail; 5781da177e4SLinus Torvalds 5791da177e4SLinus Torvalds if (*link == '/') { 5802a737871SAl Viro set_root(nd); 5811d957f9bSJan Blunck path_put(&nd->path); 5822a737871SAl Viro nd->path = nd->root; 5832a737871SAl Viro path_get(&nd->root); 5841da177e4SLinus Torvalds } 585b4091d5fSChristoph Hellwig 5861da177e4SLinus Torvalds res = link_path_walk(link, nd); 5871da177e4SLinus Torvalds if (nd->depth || res || nd->last_type!=LAST_NORM) 5881da177e4SLinus Torvalds return res; 5891da177e4SLinus Torvalds /* 5901da177e4SLinus Torvalds * If it is an iterative symlinks resolution in open_namei() we 5911da177e4SLinus Torvalds * have to copy the last component. And all that crap because of 5921da177e4SLinus Torvalds * bloody create() on broken symlinks. Furrfu... 5931da177e4SLinus Torvalds */ 5941da177e4SLinus Torvalds name = __getname(); 5951da177e4SLinus Torvalds if (unlikely(!name)) { 5961d957f9bSJan Blunck path_put(&nd->path); 5971da177e4SLinus Torvalds return -ENOMEM; 5981da177e4SLinus Torvalds } 5991da177e4SLinus Torvalds strcpy(name, nd->last.name); 6001da177e4SLinus Torvalds nd->last.name = name; 6011da177e4SLinus Torvalds return 0; 6021da177e4SLinus Torvalds fail: 6031d957f9bSJan Blunck path_put(&nd->path); 6041da177e4SLinus Torvalds return PTR_ERR(link); 6051da177e4SLinus Torvalds } 6061da177e4SLinus Torvalds 6071d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 608051d3812SIan Kent { 609051d3812SIan Kent dput(path->dentry); 6104ac91378SJan Blunck if (path->mnt != nd->path.mnt) 611051d3812SIan Kent mntput(path->mnt); 612051d3812SIan Kent } 613051d3812SIan Kent 614051d3812SIan Kent static inline void path_to_nameidata(struct path *path, struct nameidata *nd) 615051d3812SIan Kent { 6164ac91378SJan Blunck dput(nd->path.dentry); 6174ac91378SJan Blunck if (nd->path.mnt != path->mnt) 6184ac91378SJan Blunck mntput(nd->path.mnt); 6194ac91378SJan Blunck nd->path.mnt = path->mnt; 6204ac91378SJan Blunck nd->path.dentry = path->dentry; 621051d3812SIan Kent } 622051d3812SIan Kent 623f1662356SArjan van de Ven static __always_inline int __do_follow_link(struct path *path, struct nameidata *nd) 6241da177e4SLinus Torvalds { 6251da177e4SLinus Torvalds int error; 626cc314eefSLinus Torvalds void *cookie; 627cd4e91d3SAl Viro struct dentry *dentry = path->dentry; 6281da177e4SLinus Torvalds 629d671a1cbSAl Viro touch_atime(path->mnt, dentry); 6301da177e4SLinus Torvalds nd_set_link(nd, NULL); 631cd4e91d3SAl Viro 6324ac91378SJan Blunck if (path->mnt != nd->path.mnt) { 633051d3812SIan Kent path_to_nameidata(path, nd); 634051d3812SIan Kent dget(dentry); 635051d3812SIan Kent } 636cd4e91d3SAl Viro mntget(path->mnt); 637cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, nd); 638cc314eefSLinus Torvalds error = PTR_ERR(cookie); 639cc314eefSLinus Torvalds if (!IS_ERR(cookie)) { 6401da177e4SLinus Torvalds char *s = nd_get_link(nd); 641cc314eefSLinus Torvalds error = 0; 6421da177e4SLinus Torvalds if (s) 6431da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 6441da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 645cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, nd, cookie); 6461da177e4SLinus Torvalds } 64709da5916SJan Blunck path_put(path); 6481da177e4SLinus Torvalds 6491da177e4SLinus Torvalds return error; 6501da177e4SLinus Torvalds } 6511da177e4SLinus Torvalds 6521da177e4SLinus Torvalds /* 6531da177e4SLinus Torvalds * This limits recursive symlink follows to 8, while 6541da177e4SLinus Torvalds * limiting consecutive symlinks to 40. 6551da177e4SLinus Torvalds * 6561da177e4SLinus Torvalds * Without that kind of total limit, nasty chains of consecutive 6571da177e4SLinus Torvalds * symlinks can cause almost arbitrarily long lookups. 6581da177e4SLinus Torvalds */ 65990ebe565SAl Viro static inline int do_follow_link(struct path *path, struct nameidata *nd) 6601da177e4SLinus Torvalds { 6611da177e4SLinus Torvalds int err = -ELOOP; 6621da177e4SLinus Torvalds if (current->link_count >= MAX_NESTED_LINKS) 6631da177e4SLinus Torvalds goto loop; 6641da177e4SLinus Torvalds if (current->total_link_count >= 40) 6651da177e4SLinus Torvalds goto loop; 6661da177e4SLinus Torvalds BUG_ON(nd->depth >= MAX_NESTED_LINKS); 6671da177e4SLinus Torvalds cond_resched(); 66890ebe565SAl Viro err = security_inode_follow_link(path->dentry, nd); 6691da177e4SLinus Torvalds if (err) 6701da177e4SLinus Torvalds goto loop; 6711da177e4SLinus Torvalds current->link_count++; 6721da177e4SLinus Torvalds current->total_link_count++; 6731da177e4SLinus Torvalds nd->depth++; 674cd4e91d3SAl Viro err = __do_follow_link(path, nd); 6751da177e4SLinus Torvalds current->link_count--; 6761da177e4SLinus Torvalds nd->depth--; 6771da177e4SLinus Torvalds return err; 6781da177e4SLinus Torvalds loop: 6791d957f9bSJan Blunck path_put_conditional(path, nd); 6801d957f9bSJan Blunck path_put(&nd->path); 6811da177e4SLinus Torvalds return err; 6821da177e4SLinus Torvalds } 6831da177e4SLinus Torvalds 684bab77ebfSAl Viro int follow_up(struct path *path) 6851da177e4SLinus Torvalds { 6861da177e4SLinus Torvalds struct vfsmount *parent; 6871da177e4SLinus Torvalds struct dentry *mountpoint; 6881da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 689bab77ebfSAl Viro parent = path->mnt->mnt_parent; 690bab77ebfSAl Viro if (parent == path->mnt) { 6911da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 6921da177e4SLinus Torvalds return 0; 6931da177e4SLinus Torvalds } 6941da177e4SLinus Torvalds mntget(parent); 695bab77ebfSAl Viro mountpoint = dget(path->mnt->mnt_mountpoint); 6961da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 697bab77ebfSAl Viro dput(path->dentry); 698bab77ebfSAl Viro path->dentry = mountpoint; 699bab77ebfSAl Viro mntput(path->mnt); 700bab77ebfSAl Viro path->mnt = parent; 7011da177e4SLinus Torvalds return 1; 7021da177e4SLinus Torvalds } 7031da177e4SLinus Torvalds 7041da177e4SLinus Torvalds /* no need for dcache_lock, as serialization is taken care in 7051da177e4SLinus Torvalds * namespace.c 7061da177e4SLinus Torvalds */ 707463ffb2eSAl Viro static int __follow_mount(struct path *path) 708463ffb2eSAl Viro { 709463ffb2eSAl Viro int res = 0; 710463ffb2eSAl Viro while (d_mountpoint(path->dentry)) { 7111c755af4SAl Viro struct vfsmount *mounted = lookup_mnt(path); 712463ffb2eSAl Viro if (!mounted) 713463ffb2eSAl Viro break; 714463ffb2eSAl Viro dput(path->dentry); 715463ffb2eSAl Viro if (res) 716463ffb2eSAl Viro mntput(path->mnt); 717463ffb2eSAl Viro path->mnt = mounted; 718463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 719463ffb2eSAl Viro res = 1; 720463ffb2eSAl Viro } 721463ffb2eSAl Viro return res; 722463ffb2eSAl Viro } 723463ffb2eSAl Viro 72479ed0226SAl Viro static void follow_mount(struct path *path) 7251da177e4SLinus Torvalds { 72679ed0226SAl Viro while (d_mountpoint(path->dentry)) { 7271c755af4SAl Viro struct vfsmount *mounted = lookup_mnt(path); 7281da177e4SLinus Torvalds if (!mounted) 7291da177e4SLinus Torvalds break; 73079ed0226SAl Viro dput(path->dentry); 73179ed0226SAl Viro mntput(path->mnt); 73279ed0226SAl Viro path->mnt = mounted; 73379ed0226SAl Viro path->dentry = dget(mounted->mnt_root); 7341da177e4SLinus Torvalds } 7351da177e4SLinus Torvalds } 7361da177e4SLinus Torvalds 7371da177e4SLinus Torvalds /* no need for dcache_lock, as serialization is taken care in 7381da177e4SLinus Torvalds * namespace.c 7391da177e4SLinus Torvalds */ 7409393bd07SAl Viro int follow_down(struct path *path) 7411da177e4SLinus Torvalds { 7421da177e4SLinus Torvalds struct vfsmount *mounted; 7431da177e4SLinus Torvalds 7441c755af4SAl Viro mounted = lookup_mnt(path); 7451da177e4SLinus Torvalds if (mounted) { 7469393bd07SAl Viro dput(path->dentry); 7479393bd07SAl Viro mntput(path->mnt); 7489393bd07SAl Viro path->mnt = mounted; 7499393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 7501da177e4SLinus Torvalds return 1; 7511da177e4SLinus Torvalds } 7521da177e4SLinus Torvalds return 0; 7531da177e4SLinus Torvalds } 7541da177e4SLinus Torvalds 755f1662356SArjan van de Ven static __always_inline void follow_dotdot(struct nameidata *nd) 7561da177e4SLinus Torvalds { 7572a737871SAl Viro set_root(nd); 758e518ddb7SAndreas Mohr 7591da177e4SLinus Torvalds while(1) { 7601da177e4SLinus Torvalds struct vfsmount *parent; 7614ac91378SJan Blunck struct dentry *old = nd->path.dentry; 7621da177e4SLinus Torvalds 7632a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 7642a737871SAl Viro nd->path.mnt == nd->root.mnt) { 7651da177e4SLinus Torvalds break; 7661da177e4SLinus Torvalds } 7671da177e4SLinus Torvalds spin_lock(&dcache_lock); 7684ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 7694ac91378SJan Blunck nd->path.dentry = dget(nd->path.dentry->d_parent); 7701da177e4SLinus Torvalds spin_unlock(&dcache_lock); 7711da177e4SLinus Torvalds dput(old); 7721da177e4SLinus Torvalds break; 7731da177e4SLinus Torvalds } 7741da177e4SLinus Torvalds spin_unlock(&dcache_lock); 7751da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 7764ac91378SJan Blunck parent = nd->path.mnt->mnt_parent; 7774ac91378SJan Blunck if (parent == nd->path.mnt) { 7781da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7791da177e4SLinus Torvalds break; 7801da177e4SLinus Torvalds } 7811da177e4SLinus Torvalds mntget(parent); 7824ac91378SJan Blunck nd->path.dentry = dget(nd->path.mnt->mnt_mountpoint); 7831da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7841da177e4SLinus Torvalds dput(old); 7854ac91378SJan Blunck mntput(nd->path.mnt); 7864ac91378SJan Blunck nd->path.mnt = parent; 7871da177e4SLinus Torvalds } 78879ed0226SAl Viro follow_mount(&nd->path); 7891da177e4SLinus Torvalds } 7901da177e4SLinus Torvalds 7911da177e4SLinus Torvalds /* 7921da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 7931da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 7941da177e4SLinus Torvalds * It _is_ time-critical. 7951da177e4SLinus Torvalds */ 7961da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 7971da177e4SLinus Torvalds struct path *path) 7981da177e4SLinus Torvalds { 7994ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 8004ac91378SJan Blunck struct dentry *dentry = __d_lookup(nd->path.dentry, name); 8011da177e4SLinus Torvalds 8021da177e4SLinus Torvalds if (!dentry) 8031da177e4SLinus Torvalds goto need_lookup; 8041da177e4SLinus Torvalds if (dentry->d_op && dentry->d_op->d_revalidate) 8051da177e4SLinus Torvalds goto need_revalidate; 8061da177e4SLinus Torvalds done: 8071da177e4SLinus Torvalds path->mnt = mnt; 8081da177e4SLinus Torvalds path->dentry = dentry; 809634ee701SAl Viro __follow_mount(path); 8101da177e4SLinus Torvalds return 0; 8111da177e4SLinus Torvalds 8121da177e4SLinus Torvalds need_lookup: 8134ac91378SJan Blunck dentry = real_lookup(nd->path.dentry, name, nd); 8141da177e4SLinus Torvalds if (IS_ERR(dentry)) 8151da177e4SLinus Torvalds goto fail; 8161da177e4SLinus Torvalds goto done; 8171da177e4SLinus Torvalds 8181da177e4SLinus Torvalds need_revalidate: 819bcdc5e01SIan Kent dentry = do_revalidate(dentry, nd); 820bcdc5e01SIan Kent if (!dentry) 8211da177e4SLinus Torvalds goto need_lookup; 822bcdc5e01SIan Kent if (IS_ERR(dentry)) 823bcdc5e01SIan Kent goto fail; 824bcdc5e01SIan Kent goto done; 8251da177e4SLinus Torvalds 8261da177e4SLinus Torvalds fail: 8271da177e4SLinus Torvalds return PTR_ERR(dentry); 8281da177e4SLinus Torvalds } 8291da177e4SLinus Torvalds 8301da177e4SLinus Torvalds /* 8311da177e4SLinus Torvalds * Name resolution. 832ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 833ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 8341da177e4SLinus Torvalds * 835ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 836ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 8371da177e4SLinus Torvalds */ 838fc9b52cdSHarvey Harrison static int __link_path_walk(const char *name, struct nameidata *nd) 8391da177e4SLinus Torvalds { 8401da177e4SLinus Torvalds struct path next; 8411da177e4SLinus Torvalds struct inode *inode; 8421da177e4SLinus Torvalds int err; 8431da177e4SLinus Torvalds unsigned int lookup_flags = nd->flags; 8441da177e4SLinus Torvalds 8451da177e4SLinus Torvalds while (*name=='/') 8461da177e4SLinus Torvalds name++; 8471da177e4SLinus Torvalds if (!*name) 8481da177e4SLinus Torvalds goto return_reval; 8491da177e4SLinus Torvalds 8504ac91378SJan Blunck inode = nd->path.dentry->d_inode; 8511da177e4SLinus Torvalds if (nd->depth) 852f55eab82STrond Myklebust lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE); 8531da177e4SLinus Torvalds 8541da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 8551da177e4SLinus Torvalds for(;;) { 8561da177e4SLinus Torvalds unsigned long hash; 8571da177e4SLinus Torvalds struct qstr this; 8581da177e4SLinus Torvalds unsigned int c; 8591da177e4SLinus Torvalds 860cdce5d6bSTrond Myklebust nd->flags |= LOOKUP_CONTINUE; 861672b16b2SAl Viro err = exec_permission_lite(inode); 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)) { 1545acd0c935SMimi Zohar error = -EPERM; 15461da177e4SLinus Torvalds if ((flag & FMODE_WRITE) && !(flag & O_APPEND)) 1547acd0c935SMimi Zohar goto err_out; 15481da177e4SLinus Torvalds if (flag & O_TRUNC) 1549acd0c935SMimi Zohar goto err_out; 15501da177e4SLinus Torvalds } 15511da177e4SLinus Torvalds 15521da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 15531da177e4SLinus Torvalds if (flag & O_NOATIME) 1554acd0c935SMimi Zohar if (!is_owner_or_cap(inode)) { 1555acd0c935SMimi Zohar error = -EPERM; 1556acd0c935SMimi Zohar goto err_out; 1557acd0c935SMimi Zohar } 15581da177e4SLinus Torvalds 15591da177e4SLinus Torvalds /* 15601da177e4SLinus Torvalds * Ensure there are no outstanding leases on the file. 15611da177e4SLinus Torvalds */ 15621da177e4SLinus Torvalds error = break_lease(inode, flag); 15631da177e4SLinus Torvalds if (error) 1564acd0c935SMimi Zohar goto err_out; 15651da177e4SLinus Torvalds 15661da177e4SLinus Torvalds if (flag & O_TRUNC) { 15671da177e4SLinus Torvalds error = get_write_access(inode); 15681da177e4SLinus Torvalds if (error) 1569acd0c935SMimi Zohar goto err_out; 15701da177e4SLinus Torvalds 15711da177e4SLinus Torvalds /* 15721da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 15731da177e4SLinus Torvalds */ 15741da177e4SLinus Torvalds error = locks_verify_locked(inode); 1575be6d3e56SKentaro Takeda if (!error) 15763fb64190SChristoph Hellwig error = security_path_truncate(path, 0, 1577be6d3e56SKentaro Takeda ATTR_MTIME|ATTR_CTIME|ATTR_OPEN); 15781da177e4SLinus Torvalds if (!error) { 15799e3509e2SJan Kara vfs_dq_init(inode); 15801da177e4SLinus Torvalds 1581d139d7ffSMiklos Szeredi error = do_truncate(dentry, 0, 1582d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 1583d139d7ffSMiklos Szeredi NULL); 15841da177e4SLinus Torvalds } 15851da177e4SLinus Torvalds put_write_access(inode); 15861da177e4SLinus Torvalds if (error) 1587acd0c935SMimi Zohar goto err_out; 15881da177e4SLinus Torvalds } else 15891da177e4SLinus Torvalds if (flag & FMODE_WRITE) 15909e3509e2SJan Kara vfs_dq_init(inode); 15911da177e4SLinus Torvalds 15921da177e4SLinus Torvalds return 0; 1593acd0c935SMimi Zohar err_out: 1594acd0c935SMimi Zohar ima_counts_put(path, acc_mode ? 1595acd0c935SMimi Zohar acc_mode & (MAY_READ | MAY_WRITE | MAY_EXEC) : 1596acd0c935SMimi Zohar ACC_MODE(flag) & (MAY_READ | MAY_WRITE)); 1597acd0c935SMimi Zohar return error; 15981da177e4SLinus Torvalds } 15991da177e4SLinus Torvalds 1600d57999e1SDave Hansen /* 1601d57999e1SDave Hansen * Be careful about ever adding any more callers of this 1602d57999e1SDave Hansen * function. Its flags must be in the namei format, not 1603d57999e1SDave Hansen * what get passed to sys_open(). 1604d57999e1SDave Hansen */ 1605d57999e1SDave Hansen static int __open_namei_create(struct nameidata *nd, struct path *path, 1606aab520e2SDave Hansen int flag, int mode) 1607aab520e2SDave Hansen { 1608aab520e2SDave Hansen int error; 16094ac91378SJan Blunck struct dentry *dir = nd->path.dentry; 1610aab520e2SDave Hansen 1611aab520e2SDave Hansen if (!IS_POSIXACL(dir->d_inode)) 1612ce3b0f8dSAl Viro mode &= ~current_umask(); 1613be6d3e56SKentaro Takeda error = security_path_mknod(&nd->path, path->dentry, mode, 0); 1614be6d3e56SKentaro Takeda if (error) 1615be6d3e56SKentaro Takeda goto out_unlock; 1616aab520e2SDave Hansen error = vfs_create(dir->d_inode, path->dentry, mode, nd); 1617be6d3e56SKentaro Takeda out_unlock: 1618aab520e2SDave Hansen mutex_unlock(&dir->d_inode->i_mutex); 16194ac91378SJan Blunck dput(nd->path.dentry); 16204ac91378SJan Blunck nd->path.dentry = path->dentry; 1621aab520e2SDave Hansen if (error) 1622aab520e2SDave Hansen return error; 1623aab520e2SDave Hansen /* Don't check for write permission, don't truncate */ 16243fb64190SChristoph Hellwig return may_open(&nd->path, 0, flag & ~O_TRUNC); 1625aab520e2SDave Hansen } 1626aab520e2SDave Hansen 16271da177e4SLinus Torvalds /* 1628d57999e1SDave Hansen * Note that while the flag value (low two bits) for sys_open means: 1629d57999e1SDave Hansen * 00 - read-only 1630d57999e1SDave Hansen * 01 - write-only 1631d57999e1SDave Hansen * 10 - read-write 1632d57999e1SDave Hansen * 11 - special 1633d57999e1SDave Hansen * it is changed into 1634d57999e1SDave Hansen * 00 - no permissions needed 1635d57999e1SDave Hansen * 01 - read-permission 1636d57999e1SDave Hansen * 10 - write-permission 1637d57999e1SDave Hansen * 11 - read-write 1638d57999e1SDave Hansen * for the internal routines (ie open_namei()/follow_link() etc) 1639d57999e1SDave Hansen * This is more logical, and also allows the 00 "no perm needed" 1640d57999e1SDave Hansen * to be used for symlinks (where the permissions are checked 1641d57999e1SDave Hansen * later). 1642d57999e1SDave Hansen * 1643d57999e1SDave Hansen */ 1644d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 1645d57999e1SDave Hansen { 1646d57999e1SDave Hansen if ((flag+1) & O_ACCMODE) 1647d57999e1SDave Hansen flag++; 1648d57999e1SDave Hansen return flag; 1649d57999e1SDave Hansen } 1650d57999e1SDave Hansen 16514a3fd211SDave Hansen static int open_will_write_to_fs(int flag, struct inode *inode) 16524a3fd211SDave Hansen { 1653d57999e1SDave Hansen /* 16544a3fd211SDave Hansen * We'll never write to the fs underlying 16554a3fd211SDave Hansen * a device file. 16564a3fd211SDave Hansen */ 16574a3fd211SDave Hansen if (special_file(inode->i_mode)) 16584a3fd211SDave Hansen return 0; 16594a3fd211SDave Hansen return (flag & O_TRUNC); 16604a3fd211SDave Hansen } 16614a3fd211SDave Hansen 16624a3fd211SDave Hansen /* 16634a3fd211SDave Hansen * Note that the low bits of the passed in "open_flag" 16644a3fd211SDave Hansen * are not the same as in the local variable "flag". See 16654a3fd211SDave Hansen * open_to_namei_flags() for more details. 16661da177e4SLinus Torvalds */ 1667a70e65dfSChristoph Hellwig struct file *do_filp_open(int dfd, const char *pathname, 16686e8341a1SAl Viro int open_flag, int mode, int acc_mode) 16691da177e4SLinus Torvalds { 16704a3fd211SDave Hansen struct file *filp; 1671a70e65dfSChristoph Hellwig struct nameidata nd; 16726e8341a1SAl Viro int error; 16734e7506e4SAl Viro struct path path; 16741da177e4SLinus Torvalds struct dentry *dir; 16751da177e4SLinus Torvalds int count = 0; 16764a3fd211SDave Hansen int will_write; 1677d57999e1SDave Hansen int flag = open_to_namei_flags(open_flag); 16781da177e4SLinus Torvalds 16796e8341a1SAl Viro if (!acc_mode) 1680b77b0646SAl Viro acc_mode = MAY_OPEN | ACC_MODE(flag); 16811da177e4SLinus Torvalds 1682834f2a4aSTrond Myklebust /* O_TRUNC implies we need access checks for write permissions */ 1683834f2a4aSTrond Myklebust if (flag & O_TRUNC) 1684834f2a4aSTrond Myklebust acc_mode |= MAY_WRITE; 1685834f2a4aSTrond Myklebust 16861da177e4SLinus Torvalds /* Allow the LSM permission hook to distinguish append 16871da177e4SLinus Torvalds access from general write access. */ 16881da177e4SLinus Torvalds if (flag & O_APPEND) 16891da177e4SLinus Torvalds acc_mode |= MAY_APPEND; 16901da177e4SLinus Torvalds 16911da177e4SLinus Torvalds /* 16921da177e4SLinus Torvalds * The simplest case - just a plain lookup. 16931da177e4SLinus Torvalds */ 16941da177e4SLinus Torvalds if (!(flag & O_CREAT)) { 16955590ff0dSUlrich Drepper error = path_lookup_open(dfd, pathname, lookup_flags(flag), 1696a70e65dfSChristoph Hellwig &nd, flag); 16971da177e4SLinus Torvalds if (error) 1698a70e65dfSChristoph Hellwig return ERR_PTR(error); 16991da177e4SLinus Torvalds goto ok; 17001da177e4SLinus Torvalds } 17011da177e4SLinus Torvalds 17021da177e4SLinus Torvalds /* 17031da177e4SLinus Torvalds * Create - we need to know the parent. 17041da177e4SLinus Torvalds */ 17059b4a9b14SAl Viro error = path_init(dfd, pathname, LOOKUP_PARENT, &nd); 17061da177e4SLinus Torvalds if (error) 1707a70e65dfSChristoph Hellwig return ERR_PTR(error); 17089b4a9b14SAl Viro error = path_walk(pathname, &nd); 1709654f562cSJ. R. Okajima if (error) { 1710654f562cSJ. R. Okajima if (nd.root.mnt) 1711654f562cSJ. R. Okajima path_put(&nd.root); 17129b4a9b14SAl Viro return ERR_PTR(error); 1713654f562cSJ. R. Okajima } 17149b4a9b14SAl Viro if (unlikely(!audit_dummy_context())) 17159b4a9b14SAl Viro audit_inode(pathname, nd.path.dentry); 17161da177e4SLinus Torvalds 17171da177e4SLinus Torvalds /* 17181da177e4SLinus Torvalds * We have the parent and last component. First of all, check 17191da177e4SLinus Torvalds * that we are not asked to creat(2) an obvious directory - that 17201da177e4SLinus Torvalds * will not do. 17211da177e4SLinus Torvalds */ 17221da177e4SLinus Torvalds error = -EISDIR; 1723a70e65dfSChristoph Hellwig if (nd.last_type != LAST_NORM || nd.last.name[nd.last.len]) 17248737f3a1SAl Viro goto exit_parent; 17251da177e4SLinus Torvalds 17268737f3a1SAl Viro error = -ENFILE; 17278737f3a1SAl Viro filp = get_empty_filp(); 17288737f3a1SAl Viro if (filp == NULL) 17298737f3a1SAl Viro goto exit_parent; 17308737f3a1SAl Viro nd.intent.open.file = filp; 17318737f3a1SAl Viro nd.intent.open.flags = flag; 17328737f3a1SAl Viro nd.intent.open.create_mode = mode; 1733a70e65dfSChristoph Hellwig dir = nd.path.dentry; 1734a70e65dfSChristoph Hellwig nd.flags &= ~LOOKUP_PARENT; 17358737f3a1SAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_OPEN; 17363516586aSAl Viro if (flag & O_EXCL) 17373516586aSAl Viro nd.flags |= LOOKUP_EXCL; 17381b1dcc1bSJes Sorensen mutex_lock(&dir->d_inode->i_mutex); 1739a70e65dfSChristoph Hellwig path.dentry = lookup_hash(&nd); 1740a70e65dfSChristoph Hellwig path.mnt = nd.path.mnt; 17411da177e4SLinus Torvalds 17421da177e4SLinus Torvalds do_last: 17434e7506e4SAl Viro error = PTR_ERR(path.dentry); 17444e7506e4SAl Viro if (IS_ERR(path.dentry)) { 17451b1dcc1bSJes Sorensen mutex_unlock(&dir->d_inode->i_mutex); 17461da177e4SLinus Torvalds goto exit; 17471da177e4SLinus Torvalds } 17481da177e4SLinus Torvalds 1749a70e65dfSChristoph Hellwig if (IS_ERR(nd.intent.open.file)) { 1750a70e65dfSChristoph Hellwig error = PTR_ERR(nd.intent.open.file); 17514a3fd211SDave Hansen goto exit_mutex_unlock; 17524af4c52fSOleg Drokin } 17534af4c52fSOleg Drokin 17541da177e4SLinus Torvalds /* Negative dentry, just create the file */ 17554e7506e4SAl Viro if (!path.dentry->d_inode) { 17564a3fd211SDave Hansen /* 17574a3fd211SDave Hansen * This write is needed to ensure that a 17584a3fd211SDave Hansen * ro->rw transition does not occur between 17594a3fd211SDave Hansen * the time when the file is created and when 17604a3fd211SDave Hansen * a permanent write count is taken through 17614a3fd211SDave Hansen * the 'struct file' in nameidata_to_filp(). 17624a3fd211SDave Hansen */ 17634a3fd211SDave Hansen error = mnt_want_write(nd.path.mnt); 17641da177e4SLinus Torvalds if (error) 17654a3fd211SDave Hansen goto exit_mutex_unlock; 17664a3fd211SDave Hansen error = __open_namei_create(&nd, &path, flag, mode); 17674a3fd211SDave Hansen if (error) { 17684a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 17691da177e4SLinus Torvalds goto exit; 17704a3fd211SDave Hansen } 17714a3fd211SDave Hansen filp = nameidata_to_filp(&nd, open_flag); 177294e5d714SMimi Zohar if (IS_ERR(filp)) 177394e5d714SMimi Zohar ima_counts_put(&nd.path, 177494e5d714SMimi Zohar acc_mode & (MAY_READ | MAY_WRITE | 177594e5d714SMimi Zohar MAY_EXEC)); 17764a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 1777654f562cSJ. R. Okajima if (nd.root.mnt) 1778654f562cSJ. R. Okajima path_put(&nd.root); 17794a3fd211SDave Hansen return filp; 17801da177e4SLinus Torvalds } 17811da177e4SLinus Torvalds 17821da177e4SLinus Torvalds /* 17831da177e4SLinus Torvalds * It already exists. 17841da177e4SLinus Torvalds */ 17851b1dcc1bSJes Sorensen mutex_unlock(&dir->d_inode->i_mutex); 17865a190ae6SAl Viro audit_inode(pathname, path.dentry); 17871da177e4SLinus Torvalds 17881da177e4SLinus Torvalds error = -EEXIST; 17891da177e4SLinus Torvalds if (flag & O_EXCL) 17901da177e4SLinus Torvalds goto exit_dput; 17911da177e4SLinus Torvalds 1792e13b210fSAl Viro if (__follow_mount(&path)) { 17931da177e4SLinus Torvalds error = -ELOOP; 1794ba7a4c1aSAl Viro if (flag & O_NOFOLLOW) 1795ba7a4c1aSAl Viro goto exit_dput; 17961da177e4SLinus Torvalds } 17973e2efce0SAmy Griffis 17981da177e4SLinus Torvalds error = -ENOENT; 17994e7506e4SAl Viro if (!path.dentry->d_inode) 18001da177e4SLinus Torvalds goto exit_dput; 1801acfa4380SAl Viro if (path.dentry->d_inode->i_op->follow_link) 18021da177e4SLinus Torvalds goto do_link; 18031da177e4SLinus Torvalds 1804a70e65dfSChristoph Hellwig path_to_nameidata(&path, &nd); 18051da177e4SLinus Torvalds error = -EISDIR; 18064e7506e4SAl Viro if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode)) 18071da177e4SLinus Torvalds goto exit; 18081da177e4SLinus Torvalds ok: 18094a3fd211SDave Hansen /* 18104a3fd211SDave Hansen * Consider: 18114a3fd211SDave Hansen * 1. may_open() truncates a file 18124a3fd211SDave Hansen * 2. a rw->ro mount transition occurs 18134a3fd211SDave Hansen * 3. nameidata_to_filp() fails due to 18144a3fd211SDave Hansen * the ro mount. 18154a3fd211SDave Hansen * That would be inconsistent, and should 18164a3fd211SDave Hansen * be avoided. Taking this mnt write here 18174a3fd211SDave Hansen * ensures that (2) can not occur. 18184a3fd211SDave Hansen */ 18194a3fd211SDave Hansen will_write = open_will_write_to_fs(flag, nd.path.dentry->d_inode); 18204a3fd211SDave Hansen if (will_write) { 18214a3fd211SDave Hansen error = mnt_want_write(nd.path.mnt); 18221da177e4SLinus Torvalds if (error) 18231da177e4SLinus Torvalds goto exit; 18244a3fd211SDave Hansen } 18253fb64190SChristoph Hellwig error = may_open(&nd.path, acc_mode, flag); 18264a3fd211SDave Hansen if (error) { 18274a3fd211SDave Hansen if (will_write) 18284a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 18294a3fd211SDave Hansen goto exit; 18304a3fd211SDave Hansen } 18314a3fd211SDave Hansen filp = nameidata_to_filp(&nd, open_flag); 183294e5d714SMimi Zohar if (IS_ERR(filp)) 183394e5d714SMimi Zohar ima_counts_put(&nd.path, 183494e5d714SMimi Zohar acc_mode & (MAY_READ | MAY_WRITE | MAY_EXEC)); 18354a3fd211SDave Hansen /* 18364a3fd211SDave Hansen * It is now safe to drop the mnt write 18374a3fd211SDave Hansen * because the filp has had a write taken 18384a3fd211SDave Hansen * on its behalf. 18394a3fd211SDave Hansen */ 18404a3fd211SDave Hansen if (will_write) 18414a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 1842654f562cSJ. R. Okajima if (nd.root.mnt) 1843654f562cSJ. R. Okajima path_put(&nd.root); 18444a3fd211SDave Hansen return filp; 18451da177e4SLinus Torvalds 18464a3fd211SDave Hansen exit_mutex_unlock: 18474a3fd211SDave Hansen mutex_unlock(&dir->d_inode->i_mutex); 18481da177e4SLinus Torvalds exit_dput: 1849a70e65dfSChristoph Hellwig path_put_conditional(&path, &nd); 18501da177e4SLinus Torvalds exit: 1851a70e65dfSChristoph Hellwig if (!IS_ERR(nd.intent.open.file)) 1852a70e65dfSChristoph Hellwig release_open_intent(&nd); 18538737f3a1SAl Viro exit_parent: 18542a737871SAl Viro if (nd.root.mnt) 18552a737871SAl Viro path_put(&nd.root); 1856a70e65dfSChristoph Hellwig path_put(&nd.path); 1857a70e65dfSChristoph Hellwig return ERR_PTR(error); 18581da177e4SLinus Torvalds 18591da177e4SLinus Torvalds do_link: 18601da177e4SLinus Torvalds error = -ELOOP; 18611da177e4SLinus Torvalds if (flag & O_NOFOLLOW) 18621da177e4SLinus Torvalds goto exit_dput; 18631da177e4SLinus Torvalds /* 18641da177e4SLinus Torvalds * This is subtle. Instead of calling do_follow_link() we do the 18651da177e4SLinus Torvalds * thing by hands. The reason is that this way we have zero link_count 18661da177e4SLinus Torvalds * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT. 18671da177e4SLinus Torvalds * After that we have the parent and last component, i.e. 18681da177e4SLinus Torvalds * we are in the same situation as after the first path_walk(). 18691da177e4SLinus Torvalds * Well, almost - if the last component is normal we get its copy 18701da177e4SLinus Torvalds * stored in nd->last.name and we will have to putname() it when we 18711da177e4SLinus Torvalds * are done. Procfs-like symlinks just set LAST_BIND. 18721da177e4SLinus Torvalds */ 1873a70e65dfSChristoph Hellwig nd.flags |= LOOKUP_PARENT; 1874a70e65dfSChristoph Hellwig error = security_inode_follow_link(path.dentry, &nd); 18751da177e4SLinus Torvalds if (error) 18761da177e4SLinus Torvalds goto exit_dput; 1877a70e65dfSChristoph Hellwig error = __do_follow_link(&path, &nd); 1878de459215SKirill Korotaev if (error) { 1879de459215SKirill Korotaev /* Does someone understand code flow here? Or it is only 1880de459215SKirill Korotaev * me so stupid? Anathema to whoever designed this non-sense 1881de459215SKirill Korotaev * with "intent.open". 1882de459215SKirill Korotaev */ 1883a70e65dfSChristoph Hellwig release_open_intent(&nd); 1884654f562cSJ. R. Okajima if (nd.root.mnt) 1885654f562cSJ. R. Okajima path_put(&nd.root); 1886a70e65dfSChristoph Hellwig return ERR_PTR(error); 1887de459215SKirill Korotaev } 1888a70e65dfSChristoph Hellwig nd.flags &= ~LOOKUP_PARENT; 1889a70e65dfSChristoph Hellwig if (nd.last_type == LAST_BIND) 18901da177e4SLinus Torvalds goto ok; 18911da177e4SLinus Torvalds error = -EISDIR; 1892a70e65dfSChristoph Hellwig if (nd.last_type != LAST_NORM) 18931da177e4SLinus Torvalds goto exit; 1894a70e65dfSChristoph Hellwig if (nd.last.name[nd.last.len]) { 1895a70e65dfSChristoph Hellwig __putname(nd.last.name); 18961da177e4SLinus Torvalds goto exit; 18971da177e4SLinus Torvalds } 18981da177e4SLinus Torvalds error = -ELOOP; 18991da177e4SLinus Torvalds if (count++==32) { 1900a70e65dfSChristoph Hellwig __putname(nd.last.name); 19011da177e4SLinus Torvalds goto exit; 19021da177e4SLinus Torvalds } 1903a70e65dfSChristoph Hellwig dir = nd.path.dentry; 19041b1dcc1bSJes Sorensen mutex_lock(&dir->d_inode->i_mutex); 1905a70e65dfSChristoph Hellwig path.dentry = lookup_hash(&nd); 1906a70e65dfSChristoph Hellwig path.mnt = nd.path.mnt; 1907a70e65dfSChristoph Hellwig __putname(nd.last.name); 19081da177e4SLinus Torvalds goto do_last; 19091da177e4SLinus Torvalds } 19101da177e4SLinus Torvalds 19111da177e4SLinus Torvalds /** 1912a70e65dfSChristoph Hellwig * filp_open - open file and return file pointer 1913a70e65dfSChristoph Hellwig * 1914a70e65dfSChristoph Hellwig * @filename: path to open 1915a70e65dfSChristoph Hellwig * @flags: open flags as per the open(2) second argument 1916a70e65dfSChristoph Hellwig * @mode: mode for the new file if O_CREAT is set, else ignored 1917a70e65dfSChristoph Hellwig * 1918a70e65dfSChristoph Hellwig * This is the helper to open a file from kernelspace if you really 1919a70e65dfSChristoph Hellwig * have to. But in generally you should not do this, so please move 1920a70e65dfSChristoph Hellwig * along, nothing to see here.. 1921a70e65dfSChristoph Hellwig */ 1922a70e65dfSChristoph Hellwig struct file *filp_open(const char *filename, int flags, int mode) 1923a70e65dfSChristoph Hellwig { 19246e8341a1SAl Viro return do_filp_open(AT_FDCWD, filename, flags, mode, 0); 1925a70e65dfSChristoph Hellwig } 1926a70e65dfSChristoph Hellwig EXPORT_SYMBOL(filp_open); 1927a70e65dfSChristoph Hellwig 1928a70e65dfSChristoph Hellwig /** 19291da177e4SLinus Torvalds * lookup_create - lookup a dentry, creating it if it doesn't exist 19301da177e4SLinus Torvalds * @nd: nameidata info 19311da177e4SLinus Torvalds * @is_dir: directory flag 19321da177e4SLinus Torvalds * 19331da177e4SLinus Torvalds * Simple function to lookup and return a dentry and create it 19341da177e4SLinus Torvalds * if it doesn't exist. Is SMP-safe. 1935c663e5d8SChristoph Hellwig * 19364ac91378SJan Blunck * Returns with nd->path.dentry->d_inode->i_mutex locked. 19371da177e4SLinus Torvalds */ 19381da177e4SLinus Torvalds struct dentry *lookup_create(struct nameidata *nd, int is_dir) 19391da177e4SLinus Torvalds { 1940c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 19411da177e4SLinus Torvalds 19424ac91378SJan Blunck mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 1943c663e5d8SChristoph Hellwig /* 1944c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 1945c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 1946c663e5d8SChristoph Hellwig */ 19471da177e4SLinus Torvalds if (nd->last_type != LAST_NORM) 19481da177e4SLinus Torvalds goto fail; 19491da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 19503516586aSAl Viro nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL; 1951a634904aSASANO Masahiro nd->intent.open.flags = O_EXCL; 1952c663e5d8SChristoph Hellwig 1953c663e5d8SChristoph Hellwig /* 1954c663e5d8SChristoph Hellwig * Do the final lookup. 1955c663e5d8SChristoph Hellwig */ 195649705b77SChristoph Hellwig dentry = lookup_hash(nd); 19571da177e4SLinus Torvalds if (IS_ERR(dentry)) 19581da177e4SLinus Torvalds goto fail; 1959c663e5d8SChristoph Hellwig 1960e9baf6e5SAl Viro if (dentry->d_inode) 1961e9baf6e5SAl Viro goto eexist; 1962c663e5d8SChristoph Hellwig /* 1963c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 1964c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 1965c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 1966c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 1967c663e5d8SChristoph Hellwig */ 1968e9baf6e5SAl Viro if (unlikely(!is_dir && nd->last.name[nd->last.len])) { 19691da177e4SLinus Torvalds dput(dentry); 19701da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 1971e9baf6e5SAl Viro } 1972e9baf6e5SAl Viro return dentry; 1973e9baf6e5SAl Viro eexist: 1974e9baf6e5SAl Viro dput(dentry); 1975e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 19761da177e4SLinus Torvalds fail: 19771da177e4SLinus Torvalds return dentry; 19781da177e4SLinus Torvalds } 1979f81a0bffSChristoph Hellwig EXPORT_SYMBOL_GPL(lookup_create); 19801da177e4SLinus Torvalds 19811da177e4SLinus Torvalds int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 19821da177e4SLinus Torvalds { 1983a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 19841da177e4SLinus Torvalds 19851da177e4SLinus Torvalds if (error) 19861da177e4SLinus Torvalds return error; 19871da177e4SLinus Torvalds 19881da177e4SLinus Torvalds if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 19891da177e4SLinus Torvalds return -EPERM; 19901da177e4SLinus Torvalds 1991acfa4380SAl Viro if (!dir->i_op->mknod) 19921da177e4SLinus Torvalds return -EPERM; 19931da177e4SLinus Torvalds 199408ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 199508ce5f16SSerge E. Hallyn if (error) 199608ce5f16SSerge E. Hallyn return error; 199708ce5f16SSerge E. Hallyn 19981da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 19991da177e4SLinus Torvalds if (error) 20001da177e4SLinus Torvalds return error; 20011da177e4SLinus Torvalds 20029e3509e2SJan Kara vfs_dq_init(dir); 20031da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 2004a74574aaSStephen Smalley if (!error) 2005f38aa942SAmy Griffis fsnotify_create(dir, dentry); 20061da177e4SLinus Torvalds return error; 20071da177e4SLinus Torvalds } 20081da177e4SLinus Torvalds 2009463c3197SDave Hansen static int may_mknod(mode_t mode) 2010463c3197SDave Hansen { 2011463c3197SDave Hansen switch (mode & S_IFMT) { 2012463c3197SDave Hansen case S_IFREG: 2013463c3197SDave Hansen case S_IFCHR: 2014463c3197SDave Hansen case S_IFBLK: 2015463c3197SDave Hansen case S_IFIFO: 2016463c3197SDave Hansen case S_IFSOCK: 2017463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 2018463c3197SDave Hansen return 0; 2019463c3197SDave Hansen case S_IFDIR: 2020463c3197SDave Hansen return -EPERM; 2021463c3197SDave Hansen default: 2022463c3197SDave Hansen return -EINVAL; 2023463c3197SDave Hansen } 2024463c3197SDave Hansen } 2025463c3197SDave Hansen 20262e4d0924SHeiko Carstens SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode, 20272e4d0924SHeiko Carstens unsigned, dev) 20281da177e4SLinus Torvalds { 20292ad94ae6SAl Viro int error; 20301da177e4SLinus Torvalds char *tmp; 20311da177e4SLinus Torvalds struct dentry *dentry; 20321da177e4SLinus Torvalds struct nameidata nd; 20331da177e4SLinus Torvalds 20341da177e4SLinus Torvalds if (S_ISDIR(mode)) 20351da177e4SLinus Torvalds return -EPERM; 20361da177e4SLinus Torvalds 20372ad94ae6SAl Viro error = user_path_parent(dfd, filename, &nd, &tmp); 20381da177e4SLinus Torvalds if (error) 20392ad94ae6SAl Viro return error; 20402ad94ae6SAl Viro 20411da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 2042463c3197SDave Hansen if (IS_ERR(dentry)) { 20431da177e4SLinus Torvalds error = PTR_ERR(dentry); 2044463c3197SDave Hansen goto out_unlock; 2045463c3197SDave Hansen } 20464ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2047ce3b0f8dSAl Viro mode &= ~current_umask(); 2048463c3197SDave Hansen error = may_mknod(mode); 2049463c3197SDave Hansen if (error) 2050463c3197SDave Hansen goto out_dput; 2051463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2052463c3197SDave Hansen if (error) 2053463c3197SDave Hansen goto out_dput; 2054be6d3e56SKentaro Takeda error = security_path_mknod(&nd.path, dentry, mode, dev); 2055be6d3e56SKentaro Takeda if (error) 2056be6d3e56SKentaro Takeda goto out_drop_write; 20571da177e4SLinus Torvalds switch (mode & S_IFMT) { 20581da177e4SLinus Torvalds case 0: case S_IFREG: 20594ac91378SJan Blunck error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); 20601da177e4SLinus Torvalds break; 20611da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 20624ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, 20631da177e4SLinus Torvalds new_decode_dev(dev)); 20641da177e4SLinus Torvalds break; 20651da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 20664ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); 20671da177e4SLinus Torvalds break; 20681da177e4SLinus Torvalds } 2069be6d3e56SKentaro Takeda out_drop_write: 2070463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2071463c3197SDave Hansen out_dput: 20721da177e4SLinus Torvalds dput(dentry); 2073463c3197SDave Hansen out_unlock: 20744ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 20751d957f9bSJan Blunck path_put(&nd.path); 20761da177e4SLinus Torvalds putname(tmp); 20771da177e4SLinus Torvalds 20781da177e4SLinus Torvalds return error; 20791da177e4SLinus Torvalds } 20801da177e4SLinus Torvalds 20813480b257SHeiko Carstens SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev) 20825590ff0dSUlrich Drepper { 20835590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 20845590ff0dSUlrich Drepper } 20855590ff0dSUlrich Drepper 20861da177e4SLinus Torvalds int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 20871da177e4SLinus Torvalds { 2088a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 20891da177e4SLinus Torvalds 20901da177e4SLinus Torvalds if (error) 20911da177e4SLinus Torvalds return error; 20921da177e4SLinus Torvalds 2093acfa4380SAl Viro if (!dir->i_op->mkdir) 20941da177e4SLinus Torvalds return -EPERM; 20951da177e4SLinus Torvalds 20961da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 20971da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 20981da177e4SLinus Torvalds if (error) 20991da177e4SLinus Torvalds return error; 21001da177e4SLinus Torvalds 21019e3509e2SJan Kara vfs_dq_init(dir); 21021da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2103a74574aaSStephen Smalley if (!error) 2104f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 21051da177e4SLinus Torvalds return error; 21061da177e4SLinus Torvalds } 21071da177e4SLinus Torvalds 21082e4d0924SHeiko Carstens SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode) 21091da177e4SLinus Torvalds { 21101da177e4SLinus Torvalds int error = 0; 21111da177e4SLinus Torvalds char * tmp; 21126902d925SDave Hansen struct dentry *dentry; 21136902d925SDave Hansen struct nameidata nd; 21141da177e4SLinus Torvalds 21152ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &tmp); 21162ad94ae6SAl Viro if (error) 21176902d925SDave Hansen goto out_err; 21181da177e4SLinus Torvalds 21191da177e4SLinus Torvalds dentry = lookup_create(&nd, 1); 21201da177e4SLinus Torvalds error = PTR_ERR(dentry); 21216902d925SDave Hansen if (IS_ERR(dentry)) 21226902d925SDave Hansen goto out_unlock; 21236902d925SDave Hansen 21244ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2125ce3b0f8dSAl Viro mode &= ~current_umask(); 2126463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2127463c3197SDave Hansen if (error) 2128463c3197SDave Hansen goto out_dput; 2129be6d3e56SKentaro Takeda error = security_path_mkdir(&nd.path, dentry, mode); 2130be6d3e56SKentaro Takeda if (error) 2131be6d3e56SKentaro Takeda goto out_drop_write; 21324ac91378SJan Blunck error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); 2133be6d3e56SKentaro Takeda out_drop_write: 2134463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2135463c3197SDave Hansen out_dput: 21361da177e4SLinus Torvalds dput(dentry); 21376902d925SDave Hansen out_unlock: 21384ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 21391d957f9bSJan Blunck path_put(&nd.path); 21401da177e4SLinus Torvalds putname(tmp); 21416902d925SDave Hansen out_err: 21421da177e4SLinus Torvalds return error; 21431da177e4SLinus Torvalds } 21441da177e4SLinus Torvalds 21453cdad428SHeiko Carstens SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode) 21465590ff0dSUlrich Drepper { 21475590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 21485590ff0dSUlrich Drepper } 21495590ff0dSUlrich Drepper 21501da177e4SLinus Torvalds /* 21511da177e4SLinus Torvalds * We try to drop the dentry early: we should have 21521da177e4SLinus Torvalds * a usage count of 2 if we're the only user of this 21531da177e4SLinus Torvalds * dentry, and if that is true (possibly after pruning 21541da177e4SLinus Torvalds * the dcache), then we drop the dentry now. 21551da177e4SLinus Torvalds * 21561da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 21571da177e4SLinus Torvalds * do a 21581da177e4SLinus Torvalds * 21591da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 21601da177e4SLinus Torvalds * return -EBUSY; 21611da177e4SLinus Torvalds * 21621da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 21631da177e4SLinus Torvalds * that is still in use by something else.. 21641da177e4SLinus Torvalds */ 21651da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 21661da177e4SLinus Torvalds { 21671da177e4SLinus Torvalds dget(dentry); 21681da177e4SLinus Torvalds shrink_dcache_parent(dentry); 21691da177e4SLinus Torvalds spin_lock(&dcache_lock); 21701da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 21711da177e4SLinus Torvalds if (atomic_read(&dentry->d_count) == 2) 21721da177e4SLinus Torvalds __d_drop(dentry); 21731da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 21741da177e4SLinus Torvalds spin_unlock(&dcache_lock); 21751da177e4SLinus Torvalds } 21761da177e4SLinus Torvalds 21771da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 21781da177e4SLinus Torvalds { 21791da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 21801da177e4SLinus Torvalds 21811da177e4SLinus Torvalds if (error) 21821da177e4SLinus Torvalds return error; 21831da177e4SLinus Torvalds 2184acfa4380SAl Viro if (!dir->i_op->rmdir) 21851da177e4SLinus Torvalds return -EPERM; 21861da177e4SLinus Torvalds 21879e3509e2SJan Kara vfs_dq_init(dir); 21881da177e4SLinus Torvalds 21891b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 21901da177e4SLinus Torvalds dentry_unhash(dentry); 21911da177e4SLinus Torvalds if (d_mountpoint(dentry)) 21921da177e4SLinus Torvalds error = -EBUSY; 21931da177e4SLinus Torvalds else { 21941da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 21951da177e4SLinus Torvalds if (!error) { 21961da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 21971da177e4SLinus Torvalds if (!error) 21981da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 21991da177e4SLinus Torvalds } 22001da177e4SLinus Torvalds } 22011b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 22021da177e4SLinus Torvalds if (!error) { 22031da177e4SLinus Torvalds d_delete(dentry); 22041da177e4SLinus Torvalds } 22051da177e4SLinus Torvalds dput(dentry); 22061da177e4SLinus Torvalds 22071da177e4SLinus Torvalds return error; 22081da177e4SLinus Torvalds } 22091da177e4SLinus Torvalds 22105590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 22111da177e4SLinus Torvalds { 22121da177e4SLinus Torvalds int error = 0; 22131da177e4SLinus Torvalds char * name; 22141da177e4SLinus Torvalds struct dentry *dentry; 22151da177e4SLinus Torvalds struct nameidata nd; 22161da177e4SLinus Torvalds 22172ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 22181da177e4SLinus Torvalds if (error) 22192ad94ae6SAl Viro return error; 22201da177e4SLinus Torvalds 22211da177e4SLinus Torvalds switch(nd.last_type) { 22221da177e4SLinus Torvalds case LAST_DOTDOT: 22231da177e4SLinus Torvalds error = -ENOTEMPTY; 22241da177e4SLinus Torvalds goto exit1; 22251da177e4SLinus Torvalds case LAST_DOT: 22261da177e4SLinus Torvalds error = -EINVAL; 22271da177e4SLinus Torvalds goto exit1; 22281da177e4SLinus Torvalds case LAST_ROOT: 22291da177e4SLinus Torvalds error = -EBUSY; 22301da177e4SLinus Torvalds goto exit1; 22311da177e4SLinus Torvalds } 22320612d9fbSOGAWA Hirofumi 22330612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 22340612d9fbSOGAWA Hirofumi 22354ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 223649705b77SChristoph Hellwig dentry = lookup_hash(&nd); 22371da177e4SLinus Torvalds error = PTR_ERR(dentry); 22386902d925SDave Hansen if (IS_ERR(dentry)) 22396902d925SDave Hansen goto exit2; 22400622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 22410622753bSDave Hansen if (error) 22420622753bSDave Hansen goto exit3; 2243be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 2244be6d3e56SKentaro Takeda if (error) 2245be6d3e56SKentaro Takeda goto exit4; 22464ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 2247be6d3e56SKentaro Takeda exit4: 22480622753bSDave Hansen mnt_drop_write(nd.path.mnt); 22490622753bSDave Hansen exit3: 22501da177e4SLinus Torvalds dput(dentry); 22516902d925SDave Hansen exit2: 22524ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 22531da177e4SLinus Torvalds exit1: 22541d957f9bSJan Blunck path_put(&nd.path); 22551da177e4SLinus Torvalds putname(name); 22561da177e4SLinus Torvalds return error; 22571da177e4SLinus Torvalds } 22581da177e4SLinus Torvalds 22593cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 22605590ff0dSUlrich Drepper { 22615590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 22625590ff0dSUlrich Drepper } 22635590ff0dSUlrich Drepper 22641da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 22651da177e4SLinus Torvalds { 22661da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 22671da177e4SLinus Torvalds 22681da177e4SLinus Torvalds if (error) 22691da177e4SLinus Torvalds return error; 22701da177e4SLinus Torvalds 2271acfa4380SAl Viro if (!dir->i_op->unlink) 22721da177e4SLinus Torvalds return -EPERM; 22731da177e4SLinus Torvalds 22749e3509e2SJan Kara vfs_dq_init(dir); 22751da177e4SLinus Torvalds 22761b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 22771da177e4SLinus Torvalds if (d_mountpoint(dentry)) 22781da177e4SLinus Torvalds error = -EBUSY; 22791da177e4SLinus Torvalds else { 22801da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 22811da177e4SLinus Torvalds if (!error) 22821da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 22831da177e4SLinus Torvalds } 22841b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 22851da177e4SLinus Torvalds 22861da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 22871da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2288ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 22891da177e4SLinus Torvalds d_delete(dentry); 22901da177e4SLinus Torvalds } 22910eeca283SRobert Love 22921da177e4SLinus Torvalds return error; 22931da177e4SLinus Torvalds } 22941da177e4SLinus Torvalds 22951da177e4SLinus Torvalds /* 22961da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 22971b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 22981da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 22991da177e4SLinus Torvalds * while waiting on the I/O. 23001da177e4SLinus Torvalds */ 23015590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 23021da177e4SLinus Torvalds { 23032ad94ae6SAl Viro int error; 23041da177e4SLinus Torvalds char *name; 23051da177e4SLinus Torvalds struct dentry *dentry; 23061da177e4SLinus Torvalds struct nameidata nd; 23071da177e4SLinus Torvalds struct inode *inode = NULL; 23081da177e4SLinus Torvalds 23092ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 23101da177e4SLinus Torvalds if (error) 23112ad94ae6SAl Viro return error; 23122ad94ae6SAl Viro 23131da177e4SLinus Torvalds error = -EISDIR; 23141da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 23151da177e4SLinus Torvalds goto exit1; 23160612d9fbSOGAWA Hirofumi 23170612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 23180612d9fbSOGAWA Hirofumi 23194ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 232049705b77SChristoph Hellwig dentry = lookup_hash(&nd); 23211da177e4SLinus Torvalds error = PTR_ERR(dentry); 23221da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 23231da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 23241da177e4SLinus Torvalds if (nd.last.name[nd.last.len]) 23251da177e4SLinus Torvalds goto slashes; 23261da177e4SLinus Torvalds inode = dentry->d_inode; 23271da177e4SLinus Torvalds if (inode) 23281da177e4SLinus Torvalds atomic_inc(&inode->i_count); 23290622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 23300622753bSDave Hansen if (error) 23310622753bSDave Hansen goto exit2; 2332be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 2333be6d3e56SKentaro Takeda if (error) 2334be6d3e56SKentaro Takeda goto exit3; 23354ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 2336be6d3e56SKentaro Takeda exit3: 23370622753bSDave Hansen mnt_drop_write(nd.path.mnt); 23381da177e4SLinus Torvalds exit2: 23391da177e4SLinus Torvalds dput(dentry); 23401da177e4SLinus Torvalds } 23414ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 23421da177e4SLinus Torvalds if (inode) 23431da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 23441da177e4SLinus Torvalds exit1: 23451d957f9bSJan Blunck path_put(&nd.path); 23461da177e4SLinus Torvalds putname(name); 23471da177e4SLinus Torvalds return error; 23481da177e4SLinus Torvalds 23491da177e4SLinus Torvalds slashes: 23501da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 23511da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 23521da177e4SLinus Torvalds goto exit2; 23531da177e4SLinus Torvalds } 23541da177e4SLinus Torvalds 23552e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 23565590ff0dSUlrich Drepper { 23575590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 23585590ff0dSUlrich Drepper return -EINVAL; 23595590ff0dSUlrich Drepper 23605590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 23615590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 23625590ff0dSUlrich Drepper 23635590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 23645590ff0dSUlrich Drepper } 23655590ff0dSUlrich Drepper 23663480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 23675590ff0dSUlrich Drepper { 23685590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 23695590ff0dSUlrich Drepper } 23705590ff0dSUlrich Drepper 2371db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 23721da177e4SLinus Torvalds { 2373a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 23741da177e4SLinus Torvalds 23751da177e4SLinus Torvalds if (error) 23761da177e4SLinus Torvalds return error; 23771da177e4SLinus Torvalds 2378acfa4380SAl Viro if (!dir->i_op->symlink) 23791da177e4SLinus Torvalds return -EPERM; 23801da177e4SLinus Torvalds 23811da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 23821da177e4SLinus Torvalds if (error) 23831da177e4SLinus Torvalds return error; 23841da177e4SLinus Torvalds 23859e3509e2SJan Kara vfs_dq_init(dir); 23861da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2387a74574aaSStephen Smalley if (!error) 2388f38aa942SAmy Griffis fsnotify_create(dir, dentry); 23891da177e4SLinus Torvalds return error; 23901da177e4SLinus Torvalds } 23911da177e4SLinus Torvalds 23922e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 23932e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 23941da177e4SLinus Torvalds { 23952ad94ae6SAl Viro int error; 23961da177e4SLinus Torvalds char *from; 23971da177e4SLinus Torvalds char *to; 23986902d925SDave Hansen struct dentry *dentry; 23996902d925SDave Hansen struct nameidata nd; 24001da177e4SLinus Torvalds 24011da177e4SLinus Torvalds from = getname(oldname); 24021da177e4SLinus Torvalds if (IS_ERR(from)) 24031da177e4SLinus Torvalds return PTR_ERR(from); 24042ad94ae6SAl Viro 24052ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 24062ad94ae6SAl Viro if (error) 24076902d925SDave Hansen goto out_putname; 24081da177e4SLinus Torvalds 24091da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 24101da177e4SLinus Torvalds error = PTR_ERR(dentry); 24116902d925SDave Hansen if (IS_ERR(dentry)) 24126902d925SDave Hansen goto out_unlock; 24136902d925SDave Hansen 241475c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 241575c3f29dSDave Hansen if (error) 241675c3f29dSDave Hansen goto out_dput; 2417be6d3e56SKentaro Takeda error = security_path_symlink(&nd.path, dentry, from); 2418be6d3e56SKentaro Takeda if (error) 2419be6d3e56SKentaro Takeda goto out_drop_write; 2420db2e747bSMiklos Szeredi error = vfs_symlink(nd.path.dentry->d_inode, dentry, from); 2421be6d3e56SKentaro Takeda out_drop_write: 242275c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 242375c3f29dSDave Hansen out_dput: 24241da177e4SLinus Torvalds dput(dentry); 24256902d925SDave Hansen out_unlock: 24264ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 24271d957f9bSJan Blunck path_put(&nd.path); 24281da177e4SLinus Torvalds putname(to); 24296902d925SDave Hansen out_putname: 24301da177e4SLinus Torvalds putname(from); 24311da177e4SLinus Torvalds return error; 24321da177e4SLinus Torvalds } 24331da177e4SLinus Torvalds 24343480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 24355590ff0dSUlrich Drepper { 24365590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 24375590ff0dSUlrich Drepper } 24385590ff0dSUlrich Drepper 24391da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 24401da177e4SLinus Torvalds { 24411da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 24421da177e4SLinus Torvalds int error; 24431da177e4SLinus Torvalds 24441da177e4SLinus Torvalds if (!inode) 24451da177e4SLinus Torvalds return -ENOENT; 24461da177e4SLinus Torvalds 2447a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 24481da177e4SLinus Torvalds if (error) 24491da177e4SLinus Torvalds return error; 24501da177e4SLinus Torvalds 24511da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 24521da177e4SLinus Torvalds return -EXDEV; 24531da177e4SLinus Torvalds 24541da177e4SLinus Torvalds /* 24551da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 24561da177e4SLinus Torvalds */ 24571da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 24581da177e4SLinus Torvalds return -EPERM; 2459acfa4380SAl Viro if (!dir->i_op->link) 24601da177e4SLinus Torvalds return -EPERM; 24617e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 24621da177e4SLinus Torvalds return -EPERM; 24631da177e4SLinus Torvalds 24641da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 24651da177e4SLinus Torvalds if (error) 24661da177e4SLinus Torvalds return error; 24671da177e4SLinus Torvalds 24687e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 24699e3509e2SJan Kara vfs_dq_init(dir); 24701da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 24717e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 2472e31e14ecSStephen Smalley if (!error) 24737e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 24741da177e4SLinus Torvalds return error; 24751da177e4SLinus Torvalds } 24761da177e4SLinus Torvalds 24771da177e4SLinus Torvalds /* 24781da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 24791da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 24801da177e4SLinus Torvalds * newname. --KAB 24811da177e4SLinus Torvalds * 24821da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 24831da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 24841da177e4SLinus Torvalds * and other special files. --ADM 24851da177e4SLinus Torvalds */ 24862e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 24872e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 24881da177e4SLinus Torvalds { 24891da177e4SLinus Torvalds struct dentry *new_dentry; 24902d8f3038SAl Viro struct nameidata nd; 24912d8f3038SAl Viro struct path old_path; 24921da177e4SLinus Torvalds int error; 24931da177e4SLinus Torvalds char *to; 24941da177e4SLinus Torvalds 249545c9b11aSUlrich Drepper if ((flags & ~AT_SYMLINK_FOLLOW) != 0) 2496c04030e1SUlrich Drepper return -EINVAL; 2497c04030e1SUlrich Drepper 24982d8f3038SAl Viro error = user_path_at(olddfd, oldname, 249945c9b11aSUlrich Drepper flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0, 25002d8f3038SAl Viro &old_path); 25011da177e4SLinus Torvalds if (error) 25022ad94ae6SAl Viro return error; 25032ad94ae6SAl Viro 25042ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 25051da177e4SLinus Torvalds if (error) 25061da177e4SLinus Torvalds goto out; 25071da177e4SLinus Torvalds error = -EXDEV; 25082d8f3038SAl Viro if (old_path.mnt != nd.path.mnt) 25091da177e4SLinus Torvalds goto out_release; 25101da177e4SLinus Torvalds new_dentry = lookup_create(&nd, 0); 25111da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 25126902d925SDave Hansen if (IS_ERR(new_dentry)) 25136902d925SDave Hansen goto out_unlock; 251475c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 251575c3f29dSDave Hansen if (error) 251675c3f29dSDave Hansen goto out_dput; 2517be6d3e56SKentaro Takeda error = security_path_link(old_path.dentry, &nd.path, new_dentry); 2518be6d3e56SKentaro Takeda if (error) 2519be6d3e56SKentaro Takeda goto out_drop_write; 25202d8f3038SAl Viro error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry); 2521be6d3e56SKentaro Takeda out_drop_write: 252275c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 252375c3f29dSDave Hansen out_dput: 25241da177e4SLinus Torvalds dput(new_dentry); 25256902d925SDave Hansen out_unlock: 25264ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 25271da177e4SLinus Torvalds out_release: 25281d957f9bSJan Blunck path_put(&nd.path); 25292ad94ae6SAl Viro putname(to); 25301da177e4SLinus Torvalds out: 25312d8f3038SAl Viro path_put(&old_path); 25321da177e4SLinus Torvalds 25331da177e4SLinus Torvalds return error; 25341da177e4SLinus Torvalds } 25351da177e4SLinus Torvalds 25363480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 25375590ff0dSUlrich Drepper { 2538c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 25395590ff0dSUlrich Drepper } 25405590ff0dSUlrich Drepper 25411da177e4SLinus Torvalds /* 25421da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 25431da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 25441da177e4SLinus Torvalds * Problems: 25451da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 25461da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 25471da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 2548a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 25491da177e4SLinus Torvalds * story. 25501da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 25511b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 25521da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 25531da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 2554a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 25551da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 25561da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 25571da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 2558a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 25591da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 25601da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 25611da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 25621da177e4SLinus Torvalds * d) some filesystems don't support opened-but-unlinked directories, 25631da177e4SLinus Torvalds * either because of layout or because they are not ready to deal with 25641da177e4SLinus Torvalds * all cases correctly. The latter will be fixed (taking this sort of 25651da177e4SLinus Torvalds * stuff into VFS), but the former is not going away. Solution: the same 25661da177e4SLinus Torvalds * trick as in rmdir(). 25671da177e4SLinus Torvalds * e) conversion from fhandle to dentry may come in the wrong moment - when 25681b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 25691da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 25701b1dcc1bSJes Sorensen * ->i_mutex on parents, which works but leads to some truely excessive 25711da177e4SLinus Torvalds * locking]. 25721da177e4SLinus Torvalds */ 257375c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 25741da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 25751da177e4SLinus Torvalds { 25761da177e4SLinus Torvalds int error = 0; 25771da177e4SLinus Torvalds struct inode *target; 25781da177e4SLinus Torvalds 25791da177e4SLinus Torvalds /* 25801da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 25811da177e4SLinus Torvalds * we'll need to flip '..'. 25821da177e4SLinus Torvalds */ 25831da177e4SLinus Torvalds if (new_dir != old_dir) { 2584f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 25851da177e4SLinus Torvalds if (error) 25861da177e4SLinus Torvalds return error; 25871da177e4SLinus Torvalds } 25881da177e4SLinus Torvalds 25891da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 25901da177e4SLinus Torvalds if (error) 25911da177e4SLinus Torvalds return error; 25921da177e4SLinus Torvalds 25931da177e4SLinus Torvalds target = new_dentry->d_inode; 25941da177e4SLinus Torvalds if (target) { 25951b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 25961da177e4SLinus Torvalds dentry_unhash(new_dentry); 25971da177e4SLinus Torvalds } 25981da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 25991da177e4SLinus Torvalds error = -EBUSY; 26001da177e4SLinus Torvalds else 26011da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 26021da177e4SLinus Torvalds if (target) { 26031da177e4SLinus Torvalds if (!error) 26041da177e4SLinus Torvalds target->i_flags |= S_DEAD; 26051b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 26061da177e4SLinus Torvalds if (d_unhashed(new_dentry)) 26071da177e4SLinus Torvalds d_rehash(new_dentry); 26081da177e4SLinus Torvalds dput(new_dentry); 26091da177e4SLinus Torvalds } 2610e31e14ecSStephen Smalley 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 return error; 26141da177e4SLinus Torvalds } 26151da177e4SLinus Torvalds 261675c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 26171da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 26181da177e4SLinus Torvalds { 26191da177e4SLinus Torvalds struct inode *target; 26201da177e4SLinus Torvalds int error; 26211da177e4SLinus Torvalds 26221da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 26231da177e4SLinus Torvalds if (error) 26241da177e4SLinus Torvalds return error; 26251da177e4SLinus Torvalds 26261da177e4SLinus Torvalds dget(new_dentry); 26271da177e4SLinus Torvalds target = new_dentry->d_inode; 26281da177e4SLinus Torvalds if (target) 26291b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 26301da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 26311da177e4SLinus Torvalds error = -EBUSY; 26321da177e4SLinus Torvalds else 26331da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 26341da177e4SLinus Torvalds if (!error) { 2635349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 26361da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 26371da177e4SLinus Torvalds } 26381da177e4SLinus Torvalds if (target) 26391b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 26401da177e4SLinus Torvalds dput(new_dentry); 26411da177e4SLinus Torvalds return error; 26421da177e4SLinus Torvalds } 26431da177e4SLinus Torvalds 26441da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 26451da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 26461da177e4SLinus Torvalds { 26471da177e4SLinus Torvalds int error; 26481da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 26490eeca283SRobert Love const char *old_name; 26501da177e4SLinus Torvalds 26511da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 26521da177e4SLinus Torvalds return 0; 26531da177e4SLinus Torvalds 26541da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 26551da177e4SLinus Torvalds if (error) 26561da177e4SLinus Torvalds return error; 26571da177e4SLinus Torvalds 26581da177e4SLinus Torvalds if (!new_dentry->d_inode) 2659a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 26601da177e4SLinus Torvalds else 26611da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 26621da177e4SLinus Torvalds if (error) 26631da177e4SLinus Torvalds return error; 26641da177e4SLinus Torvalds 2665acfa4380SAl Viro if (!old_dir->i_op->rename) 26661da177e4SLinus Torvalds return -EPERM; 26671da177e4SLinus Torvalds 26689e3509e2SJan Kara vfs_dq_init(old_dir); 26699e3509e2SJan Kara vfs_dq_init(new_dir); 26701da177e4SLinus Torvalds 26710eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 26720eeca283SRobert Love 26731da177e4SLinus Torvalds if (is_dir) 26741da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 26751da177e4SLinus Torvalds else 26761da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 26771da177e4SLinus Torvalds if (!error) { 26780eeca283SRobert Love const char *new_name = old_dentry->d_name.name; 267989204c40SJohn McCutchan fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir, 26805a190ae6SAl Viro new_dentry->d_inode, old_dentry); 26811da177e4SLinus Torvalds } 26820eeca283SRobert Love fsnotify_oldname_free(old_name); 26830eeca283SRobert Love 26841da177e4SLinus Torvalds return error; 26851da177e4SLinus Torvalds } 26861da177e4SLinus Torvalds 26872e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 26882e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 26891da177e4SLinus Torvalds { 26901da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 26911da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 26921da177e4SLinus Torvalds struct dentry *trap; 26931da177e4SLinus Torvalds struct nameidata oldnd, newnd; 26942ad94ae6SAl Viro char *from; 26952ad94ae6SAl Viro char *to; 26962ad94ae6SAl Viro int error; 26971da177e4SLinus Torvalds 26982ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 26991da177e4SLinus Torvalds if (error) 27001da177e4SLinus Torvalds goto exit; 27011da177e4SLinus Torvalds 27022ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 27031da177e4SLinus Torvalds if (error) 27041da177e4SLinus Torvalds goto exit1; 27051da177e4SLinus Torvalds 27061da177e4SLinus Torvalds error = -EXDEV; 27074ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 27081da177e4SLinus Torvalds goto exit2; 27091da177e4SLinus Torvalds 27104ac91378SJan Blunck old_dir = oldnd.path.dentry; 27111da177e4SLinus Torvalds error = -EBUSY; 27121da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 27131da177e4SLinus Torvalds goto exit2; 27141da177e4SLinus Torvalds 27154ac91378SJan Blunck new_dir = newnd.path.dentry; 27161da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 27171da177e4SLinus Torvalds goto exit2; 27181da177e4SLinus Torvalds 27190612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 27200612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 27214e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 27220612d9fbSOGAWA Hirofumi 27231da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 27241da177e4SLinus Torvalds 272549705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 27261da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 27271da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 27281da177e4SLinus Torvalds goto exit3; 27291da177e4SLinus Torvalds /* source must exist */ 27301da177e4SLinus Torvalds error = -ENOENT; 27311da177e4SLinus Torvalds if (!old_dentry->d_inode) 27321da177e4SLinus Torvalds goto exit4; 27331da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 27341da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 27351da177e4SLinus Torvalds error = -ENOTDIR; 27361da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 27371da177e4SLinus Torvalds goto exit4; 27381da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 27391da177e4SLinus Torvalds goto exit4; 27401da177e4SLinus Torvalds } 27411da177e4SLinus Torvalds /* source should not be ancestor of target */ 27421da177e4SLinus Torvalds error = -EINVAL; 27431da177e4SLinus Torvalds if (old_dentry == trap) 27441da177e4SLinus Torvalds goto exit4; 274549705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 27461da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 27471da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 27481da177e4SLinus Torvalds goto exit4; 27491da177e4SLinus Torvalds /* target should not be an ancestor of source */ 27501da177e4SLinus Torvalds error = -ENOTEMPTY; 27511da177e4SLinus Torvalds if (new_dentry == trap) 27521da177e4SLinus Torvalds goto exit5; 27531da177e4SLinus Torvalds 27549079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 27559079b1ebSDave Hansen if (error) 27569079b1ebSDave Hansen goto exit5; 2757be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 2758be6d3e56SKentaro Takeda &newnd.path, new_dentry); 2759be6d3e56SKentaro Takeda if (error) 2760be6d3e56SKentaro Takeda goto exit6; 27611da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 27621da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 2763be6d3e56SKentaro Takeda exit6: 27649079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 27651da177e4SLinus Torvalds exit5: 27661da177e4SLinus Torvalds dput(new_dentry); 27671da177e4SLinus Torvalds exit4: 27681da177e4SLinus Torvalds dput(old_dentry); 27691da177e4SLinus Torvalds exit3: 27701da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 27711da177e4SLinus Torvalds exit2: 27721d957f9bSJan Blunck path_put(&newnd.path); 27732ad94ae6SAl Viro putname(to); 27741da177e4SLinus Torvalds exit1: 27751d957f9bSJan Blunck path_put(&oldnd.path); 27761da177e4SLinus Torvalds putname(from); 27772ad94ae6SAl Viro exit: 27781da177e4SLinus Torvalds return error; 27791da177e4SLinus Torvalds } 27801da177e4SLinus Torvalds 2781a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 27825590ff0dSUlrich Drepper { 27835590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 27845590ff0dSUlrich Drepper } 27855590ff0dSUlrich Drepper 27861da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 27871da177e4SLinus Torvalds { 27881da177e4SLinus Torvalds int len; 27891da177e4SLinus Torvalds 27901da177e4SLinus Torvalds len = PTR_ERR(link); 27911da177e4SLinus Torvalds if (IS_ERR(link)) 27921da177e4SLinus Torvalds goto out; 27931da177e4SLinus Torvalds 27941da177e4SLinus Torvalds len = strlen(link); 27951da177e4SLinus Torvalds if (len > (unsigned) buflen) 27961da177e4SLinus Torvalds len = buflen; 27971da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 27981da177e4SLinus Torvalds len = -EFAULT; 27991da177e4SLinus Torvalds out: 28001da177e4SLinus Torvalds return len; 28011da177e4SLinus Torvalds } 28021da177e4SLinus Torvalds 28031da177e4SLinus Torvalds /* 28041da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 28051da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 28061da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 28071da177e4SLinus Torvalds */ 28081da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 28091da177e4SLinus Torvalds { 28101da177e4SLinus Torvalds struct nameidata nd; 2811cc314eefSLinus Torvalds void *cookie; 2812694a1764SMarcin Slusarz int res; 2813cc314eefSLinus Torvalds 28141da177e4SLinus Torvalds nd.depth = 0; 2815cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 2816694a1764SMarcin Slusarz if (IS_ERR(cookie)) 2817694a1764SMarcin Slusarz return PTR_ERR(cookie); 2818694a1764SMarcin Slusarz 2819694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 28201da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 2821cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 2822694a1764SMarcin Slusarz return res; 28231da177e4SLinus Torvalds } 28241da177e4SLinus Torvalds 28251da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 28261da177e4SLinus Torvalds { 28271da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 28281da177e4SLinus Torvalds } 28291da177e4SLinus Torvalds 28301da177e4SLinus Torvalds /* get the link contents into pagecache */ 28311da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 28321da177e4SLinus Torvalds { 2833ebd09abbSDuane Griffin char *kaddr; 28341da177e4SLinus Torvalds struct page *page; 28351da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 2836090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 28371da177e4SLinus Torvalds if (IS_ERR(page)) 28386fe6900eSNick Piggin return (char*)page; 28391da177e4SLinus Torvalds *ppage = page; 2840ebd09abbSDuane Griffin kaddr = kmap(page); 2841ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 2842ebd09abbSDuane Griffin return kaddr; 28431da177e4SLinus Torvalds } 28441da177e4SLinus Torvalds 28451da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 28461da177e4SLinus Torvalds { 28471da177e4SLinus Torvalds struct page *page = NULL; 28481da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 28491da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 28501da177e4SLinus Torvalds if (page) { 28511da177e4SLinus Torvalds kunmap(page); 28521da177e4SLinus Torvalds page_cache_release(page); 28531da177e4SLinus Torvalds } 28541da177e4SLinus Torvalds return res; 28551da177e4SLinus Torvalds } 28561da177e4SLinus Torvalds 2857cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 28581da177e4SLinus Torvalds { 2859cc314eefSLinus Torvalds struct page *page = NULL; 28601da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 2861cc314eefSLinus Torvalds return page; 28621da177e4SLinus Torvalds } 28631da177e4SLinus Torvalds 2864cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 28651da177e4SLinus Torvalds { 2866cc314eefSLinus Torvalds struct page *page = cookie; 2867cc314eefSLinus Torvalds 2868cc314eefSLinus Torvalds if (page) { 28691da177e4SLinus Torvalds kunmap(page); 28701da177e4SLinus Torvalds page_cache_release(page); 28711da177e4SLinus Torvalds } 28721da177e4SLinus Torvalds } 28731da177e4SLinus Torvalds 287454566b2cSNick Piggin /* 287554566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 287654566b2cSNick Piggin */ 287754566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 28781da177e4SLinus Torvalds { 28791da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 28800adb25d2SKirill Korotaev struct page *page; 2881afddba49SNick Piggin void *fsdata; 2882beb497abSDmitriy Monakhov int err; 28831da177e4SLinus Torvalds char *kaddr; 288454566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 288554566b2cSNick Piggin if (nofs) 288654566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 28871da177e4SLinus Torvalds 28887e53cac4SNeilBrown retry: 2889afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 289054566b2cSNick Piggin flags, &page, &fsdata); 28911da177e4SLinus Torvalds if (err) 2892afddba49SNick Piggin goto fail; 2893afddba49SNick Piggin 28941da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 28951da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 28961da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 2897afddba49SNick Piggin 2898afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 2899afddba49SNick Piggin page, fsdata); 29001da177e4SLinus Torvalds if (err < 0) 29011da177e4SLinus Torvalds goto fail; 2902afddba49SNick Piggin if (err < len-1) 2903afddba49SNick Piggin goto retry; 2904afddba49SNick Piggin 29051da177e4SLinus Torvalds mark_inode_dirty(inode); 29061da177e4SLinus Torvalds return 0; 29071da177e4SLinus Torvalds fail: 29081da177e4SLinus Torvalds return err; 29091da177e4SLinus Torvalds } 29101da177e4SLinus Torvalds 29110adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 29120adb25d2SKirill Korotaev { 29130adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 291454566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 29150adb25d2SKirill Korotaev } 29160adb25d2SKirill Korotaev 291792e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 29181da177e4SLinus Torvalds .readlink = generic_readlink, 29191da177e4SLinus Torvalds .follow_link = page_follow_link_light, 29201da177e4SLinus Torvalds .put_link = page_put_link, 29211da177e4SLinus Torvalds }; 29221da177e4SLinus Torvalds 29232d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 29241da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 29251da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 29261da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 29271da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 29281da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 29291da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 29301da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 29311da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 29321da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 29330adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 29341da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 29351da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 29361da177e4SLinus Torvalds EXPORT_SYMBOL(path_lookup); 2937d1811465SAl Viro EXPORT_SYMBOL(kern_path); 293816f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 2939f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 29408c744fb8SChristoph Hellwig EXPORT_SYMBOL(file_permission); 29411da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 29421da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 29431da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 29441da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 29451da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 29461da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 29471da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 29481da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 29491da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 29501da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 29511da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 29521da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 29531da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 29541da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 2955