11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namei.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Some corrections by tytso. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 121da177e4SLinus Torvalds * lookup logic. 131da177e4SLinus Torvalds */ 141da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 151da177e4SLinus Torvalds */ 161da177e4SLinus Torvalds 171da177e4SLinus Torvalds #include <linux/init.h> 181da177e4SLinus Torvalds #include <linux/module.h> 191da177e4SLinus Torvalds #include <linux/slab.h> 201da177e4SLinus Torvalds #include <linux/fs.h> 211da177e4SLinus Torvalds #include <linux/namei.h> 221da177e4SLinus Torvalds #include <linux/quotaops.h> 231da177e4SLinus Torvalds #include <linux/pagemap.h> 240eeca283SRobert Love #include <linux/fsnotify.h> 251da177e4SLinus Torvalds #include <linux/personality.h> 261da177e4SLinus Torvalds #include <linux/security.h> 271da177e4SLinus Torvalds #include <linux/syscalls.h> 281da177e4SLinus Torvalds #include <linux/mount.h> 291da177e4SLinus Torvalds #include <linux/audit.h> 3016f7e0feSRandy Dunlap #include <linux/capability.h> 31834f2a4aSTrond Myklebust #include <linux/file.h> 325590ff0dSUlrich Drepper #include <linux/fcntl.h> 331da177e4SLinus Torvalds #include <asm/namei.h> 341da177e4SLinus Torvalds #include <asm/uaccess.h> 351da177e4SLinus Torvalds 361da177e4SLinus Torvalds #define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE]) 371da177e4SLinus Torvalds 381da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 391da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 401da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 411da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 421da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 431da177e4SLinus Torvalds * 441da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 451da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 461da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 471da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 481da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 491da177e4SLinus Torvalds * the special cases of the former code. 501da177e4SLinus Torvalds * 511da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 521da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 531da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 541da177e4SLinus Torvalds * 551da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 561da177e4SLinus Torvalds * resolution to correspond with current state of the code. 571da177e4SLinus Torvalds * 581da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 591da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 601da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 611da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 621da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 631da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 641da177e4SLinus Torvalds */ 651da177e4SLinus Torvalds 661da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 671da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 681da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 691da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 701da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 711da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 721da177e4SLinus Torvalds * the name is a symlink pointing to a non-existant name. 731da177e4SLinus Torvalds * 741da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 751da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 761da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 771da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 781da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 791da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 801da177e4SLinus Torvalds * and in the old Linux semantics. 811da177e4SLinus Torvalds */ 821da177e4SLinus Torvalds 831da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 841da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 851da177e4SLinus Torvalds * 861da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 871da177e4SLinus Torvalds */ 881da177e4SLinus Torvalds 891da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 901da177e4SLinus Torvalds * inside the path - always follow. 911da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 921da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 931da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 941da177e4SLinus Torvalds * otherwise - don't follow. 951da177e4SLinus Torvalds * (applied in that order). 961da177e4SLinus Torvalds * 971da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 981da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 991da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1001da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1011da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1021da177e4SLinus Torvalds */ 1031da177e4SLinus Torvalds /* 1041da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 105a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1061da177e4SLinus Torvalds * any extra contention... 1071da177e4SLinus Torvalds */ 1081da177e4SLinus Torvalds 109fc9b52cdSHarvey Harrison static int link_path_walk(const char *name, struct nameidata *nd); 110c4a7808fSJosef 'Jeff' Sipek 1111da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1121da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1131da177e4SLinus Torvalds * kernel data space before using them.. 1141da177e4SLinus Torvalds * 1151da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1161da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1171da177e4SLinus Torvalds */ 118858119e1SArjan van de Ven static int do_getname(const char __user *filename, char *page) 1191da177e4SLinus Torvalds { 1201da177e4SLinus Torvalds int retval; 1211da177e4SLinus Torvalds unsigned long len = PATH_MAX; 1221da177e4SLinus Torvalds 1231da177e4SLinus Torvalds if (!segment_eq(get_fs(), KERNEL_DS)) { 1241da177e4SLinus Torvalds if ((unsigned long) filename >= TASK_SIZE) 1251da177e4SLinus Torvalds return -EFAULT; 1261da177e4SLinus Torvalds if (TASK_SIZE - (unsigned long) filename < PATH_MAX) 1271da177e4SLinus Torvalds len = TASK_SIZE - (unsigned long) filename; 1281da177e4SLinus Torvalds } 1291da177e4SLinus Torvalds 1301da177e4SLinus Torvalds retval = strncpy_from_user(page, filename, len); 1311da177e4SLinus Torvalds if (retval > 0) { 1321da177e4SLinus Torvalds if (retval < len) 1331da177e4SLinus Torvalds return 0; 1341da177e4SLinus Torvalds return -ENAMETOOLONG; 1351da177e4SLinus Torvalds } else if (!retval) 1361da177e4SLinus Torvalds retval = -ENOENT; 1371da177e4SLinus Torvalds return retval; 1381da177e4SLinus Torvalds } 1391da177e4SLinus Torvalds 1401da177e4SLinus Torvalds char * getname(const char __user * filename) 1411da177e4SLinus Torvalds { 1421da177e4SLinus Torvalds char *tmp, *result; 1431da177e4SLinus Torvalds 1441da177e4SLinus Torvalds result = ERR_PTR(-ENOMEM); 1451da177e4SLinus Torvalds tmp = __getname(); 1461da177e4SLinus Torvalds if (tmp) { 1471da177e4SLinus Torvalds int retval = do_getname(filename, tmp); 1481da177e4SLinus Torvalds 1491da177e4SLinus Torvalds result = tmp; 1501da177e4SLinus Torvalds if (retval < 0) { 1511da177e4SLinus Torvalds __putname(tmp); 1521da177e4SLinus Torvalds result = ERR_PTR(retval); 1531da177e4SLinus Torvalds } 1541da177e4SLinus Torvalds } 1551da177e4SLinus Torvalds audit_getname(result); 1561da177e4SLinus Torvalds return result; 1571da177e4SLinus Torvalds } 1581da177e4SLinus Torvalds 1591da177e4SLinus Torvalds #ifdef CONFIG_AUDITSYSCALL 1601da177e4SLinus Torvalds void putname(const char *name) 1611da177e4SLinus Torvalds { 1625ac3a9c2SAl Viro if (unlikely(!audit_dummy_context())) 1631da177e4SLinus Torvalds audit_putname(name); 1641da177e4SLinus Torvalds else 1651da177e4SLinus Torvalds __putname(name); 1661da177e4SLinus Torvalds } 1671da177e4SLinus Torvalds EXPORT_SYMBOL(putname); 1681da177e4SLinus Torvalds #endif 1691da177e4SLinus Torvalds 1701da177e4SLinus Torvalds 1711da177e4SLinus Torvalds /** 1721da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 1731da177e4SLinus Torvalds * @inode: inode to check access rights for 1741da177e4SLinus Torvalds * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 1751da177e4SLinus Torvalds * @check_acl: optional callback to check for Posix ACLs 1761da177e4SLinus Torvalds * 1771da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 1781da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 1791da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 1801da177e4SLinus Torvalds * are used for other things.. 1811da177e4SLinus Torvalds */ 1821da177e4SLinus Torvalds int generic_permission(struct inode *inode, int mask, 1831da177e4SLinus Torvalds int (*check_acl)(struct inode *inode, int mask)) 1841da177e4SLinus Torvalds { 1851da177e4SLinus Torvalds umode_t mode = inode->i_mode; 1861da177e4SLinus Torvalds 1871da177e4SLinus Torvalds if (current->fsuid == inode->i_uid) 1881da177e4SLinus Torvalds mode >>= 6; 1891da177e4SLinus Torvalds else { 1901da177e4SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) { 1911da177e4SLinus Torvalds int error = check_acl(inode, mask); 1921da177e4SLinus Torvalds if (error == -EACCES) 1931da177e4SLinus Torvalds goto check_capabilities; 1941da177e4SLinus Torvalds else if (error != -EAGAIN) 1951da177e4SLinus Torvalds return error; 1961da177e4SLinus Torvalds } 1971da177e4SLinus Torvalds 1981da177e4SLinus Torvalds if (in_group_p(inode->i_gid)) 1991da177e4SLinus Torvalds mode >>= 3; 2001da177e4SLinus Torvalds } 2011da177e4SLinus Torvalds 2021da177e4SLinus Torvalds /* 2031da177e4SLinus Torvalds * If the DACs are ok we don't need any capability check. 2041da177e4SLinus Torvalds */ 2051da177e4SLinus Torvalds if (((mode & mask & (MAY_READ|MAY_WRITE|MAY_EXEC)) == mask)) 2061da177e4SLinus Torvalds return 0; 2071da177e4SLinus Torvalds 2081da177e4SLinus Torvalds check_capabilities: 2091da177e4SLinus Torvalds /* 2101da177e4SLinus Torvalds * Read/write DACs are always overridable. 2111da177e4SLinus Torvalds * Executable DACs are overridable if at least one exec bit is set. 2121da177e4SLinus Torvalds */ 2131da177e4SLinus Torvalds if (!(mask & MAY_EXEC) || 2141da177e4SLinus Torvalds (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode)) 2151da177e4SLinus Torvalds if (capable(CAP_DAC_OVERRIDE)) 2161da177e4SLinus Torvalds return 0; 2171da177e4SLinus Torvalds 2181da177e4SLinus Torvalds /* 2191da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 2201da177e4SLinus Torvalds */ 2211da177e4SLinus Torvalds if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))) 2221da177e4SLinus Torvalds if (capable(CAP_DAC_READ_SEARCH)) 2231da177e4SLinus Torvalds return 0; 2241da177e4SLinus Torvalds 2251da177e4SLinus Torvalds return -EACCES; 2261da177e4SLinus Torvalds } 2271da177e4SLinus Torvalds 2281da177e4SLinus Torvalds int permission(struct inode *inode, int mask, struct nameidata *nd) 2291da177e4SLinus Torvalds { 2301da177e4SLinus Torvalds int retval, submask; 231c7eb2667SDave Hansen struct vfsmount *mnt = NULL; 232c7eb2667SDave Hansen 233c7eb2667SDave Hansen if (nd) 2344ac91378SJan Blunck mnt = nd->path.mnt; 2351da177e4SLinus Torvalds 2361da177e4SLinus Torvalds if (mask & MAY_WRITE) { 23722590e41SMiklos Szeredi umode_t mode = inode->i_mode; 2381da177e4SLinus Torvalds 2391da177e4SLinus Torvalds /* 2401da177e4SLinus Torvalds * Nobody gets write access to a read-only fs. 2411da177e4SLinus Torvalds */ 2421da177e4SLinus Torvalds if (IS_RDONLY(inode) && 2431da177e4SLinus Torvalds (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 2441da177e4SLinus Torvalds return -EROFS; 2451da177e4SLinus Torvalds 2461da177e4SLinus Torvalds /* 2471da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 2481da177e4SLinus Torvalds */ 2491da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 2501da177e4SLinus Torvalds return -EACCES; 2511da177e4SLinus Torvalds } 2521da177e4SLinus Torvalds 25322590e41SMiklos Szeredi if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode)) { 254a343bb77STrond Myklebust /* 25522590e41SMiklos Szeredi * MAY_EXEC on regular files is denied if the fs is mounted 25622590e41SMiklos Szeredi * with the "noexec" flag. 257a343bb77STrond Myklebust */ 258c7eb2667SDave Hansen if (mnt && (mnt->mnt_flags & MNT_NOEXEC)) 259a343bb77STrond Myklebust return -EACCES; 26022590e41SMiklos Szeredi } 261a343bb77STrond Myklebust 2621da177e4SLinus Torvalds /* Ordinary permission routines do not understand MAY_APPEND. */ 2631da177e4SLinus Torvalds submask = mask & ~MAY_APPEND; 26422590e41SMiklos Szeredi if (inode->i_op && inode->i_op->permission) { 2651da177e4SLinus Torvalds retval = inode->i_op->permission(inode, submask, nd); 26622590e41SMiklos Szeredi if (!retval) { 26722590e41SMiklos Szeredi /* 26822590e41SMiklos Szeredi * Exec permission on a regular file is denied if none 26922590e41SMiklos Szeredi * of the execute bits are set. 27022590e41SMiklos Szeredi * 27122590e41SMiklos Szeredi * This check should be done by the ->permission() 27222590e41SMiklos Szeredi * method. 27322590e41SMiklos Szeredi */ 27422590e41SMiklos Szeredi if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode) && 27522590e41SMiklos Szeredi !(inode->i_mode & S_IXUGO)) 27622590e41SMiklos Szeredi return -EACCES; 27722590e41SMiklos Szeredi } 27822590e41SMiklos Szeredi } else { 2791da177e4SLinus Torvalds retval = generic_permission(inode, submask, NULL); 28022590e41SMiklos Szeredi } 2811da177e4SLinus Torvalds if (retval) 2821da177e4SLinus Torvalds return retval; 2831da177e4SLinus Torvalds 2841da177e4SLinus Torvalds return security_inode_permission(inode, mask, nd); 2851da177e4SLinus Torvalds } 2861da177e4SLinus Torvalds 287e4543eddSChristoph Hellwig /** 288e4543eddSChristoph Hellwig * vfs_permission - check for access rights to a given path 289e4543eddSChristoph Hellwig * @nd: lookup result that describes the path 290e4543eddSChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 291e4543eddSChristoph Hellwig * 292e4543eddSChristoph Hellwig * Used to check for read/write/execute permissions on a path. 293e4543eddSChristoph Hellwig * We use "fsuid" for this, letting us set arbitrary permissions 294e4543eddSChristoph Hellwig * for filesystem access without changing the "normal" uids which 295e4543eddSChristoph Hellwig * are used for other things. 296e4543eddSChristoph Hellwig */ 297e4543eddSChristoph Hellwig int vfs_permission(struct nameidata *nd, int mask) 298e4543eddSChristoph Hellwig { 2994ac91378SJan Blunck return permission(nd->path.dentry->d_inode, mask, nd); 300e4543eddSChristoph Hellwig } 301e4543eddSChristoph Hellwig 3028c744fb8SChristoph Hellwig /** 3038c744fb8SChristoph Hellwig * file_permission - check for additional access rights to a given file 3048c744fb8SChristoph Hellwig * @file: file to check access rights for 3058c744fb8SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 3068c744fb8SChristoph Hellwig * 3078c744fb8SChristoph Hellwig * Used to check for read/write/execute permissions on an already opened 3088c744fb8SChristoph Hellwig * file. 3098c744fb8SChristoph Hellwig * 3108c744fb8SChristoph Hellwig * Note: 3118c744fb8SChristoph Hellwig * Do not use this function in new code. All access checks should 3128c744fb8SChristoph Hellwig * be done using vfs_permission(). 3138c744fb8SChristoph Hellwig */ 3148c744fb8SChristoph Hellwig int file_permission(struct file *file, int mask) 3158c744fb8SChristoph Hellwig { 3160f7fc9e4SJosef "Jeff" Sipek return permission(file->f_path.dentry->d_inode, mask, NULL); 3178c744fb8SChristoph Hellwig } 3188c744fb8SChristoph Hellwig 3191da177e4SLinus Torvalds /* 3201da177e4SLinus Torvalds * get_write_access() gets write permission for a file. 3211da177e4SLinus Torvalds * put_write_access() releases this write permission. 3221da177e4SLinus Torvalds * This is used for regular files. 3231da177e4SLinus Torvalds * We cannot support write (and maybe mmap read-write shared) accesses and 3241da177e4SLinus Torvalds * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode 3251da177e4SLinus Torvalds * can have the following values: 3261da177e4SLinus Torvalds * 0: no writers, no VM_DENYWRITE mappings 3271da177e4SLinus Torvalds * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist 3281da177e4SLinus Torvalds * > 0: (i_writecount) users are writing to the file. 3291da177e4SLinus Torvalds * 3301da177e4SLinus Torvalds * Normally we operate on that counter with atomic_{inc,dec} and it's safe 3311da177e4SLinus Torvalds * except for the cases where we don't hold i_writecount yet. Then we need to 3321da177e4SLinus Torvalds * use {get,deny}_write_access() - these functions check the sign and refuse 3331da177e4SLinus Torvalds * to do the change if sign is wrong. Exclusion between them is provided by 3341da177e4SLinus Torvalds * the inode->i_lock spinlock. 3351da177e4SLinus Torvalds */ 3361da177e4SLinus Torvalds 3371da177e4SLinus Torvalds int get_write_access(struct inode * inode) 3381da177e4SLinus Torvalds { 3391da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3401da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) < 0) { 3411da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3421da177e4SLinus Torvalds return -ETXTBSY; 3431da177e4SLinus Torvalds } 3441da177e4SLinus Torvalds atomic_inc(&inode->i_writecount); 3451da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3461da177e4SLinus Torvalds 3471da177e4SLinus Torvalds return 0; 3481da177e4SLinus Torvalds } 3491da177e4SLinus Torvalds 3501da177e4SLinus Torvalds int deny_write_access(struct file * file) 3511da177e4SLinus Torvalds { 3520f7fc9e4SJosef "Jeff" Sipek struct inode *inode = file->f_path.dentry->d_inode; 3531da177e4SLinus Torvalds 3541da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3551da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) > 0) { 3561da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3571da177e4SLinus Torvalds return -ETXTBSY; 3581da177e4SLinus Torvalds } 3591da177e4SLinus Torvalds atomic_dec(&inode->i_writecount); 3601da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3611da177e4SLinus Torvalds 3621da177e4SLinus Torvalds return 0; 3631da177e4SLinus Torvalds } 3641da177e4SLinus Torvalds 3651d957f9bSJan Blunck /** 3661d957f9bSJan Blunck * path_put - put a reference to a path 3671d957f9bSJan Blunck * @path: path to put the reference to 3681d957f9bSJan Blunck * 3691d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 3701d957f9bSJan Blunck */ 3711d957f9bSJan Blunck void path_put(struct path *path) 3721da177e4SLinus Torvalds { 3731d957f9bSJan Blunck dput(path->dentry); 3741d957f9bSJan Blunck mntput(path->mnt); 3751da177e4SLinus Torvalds } 3761d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 3771da177e4SLinus Torvalds 378834f2a4aSTrond Myklebust /** 379834f2a4aSTrond Myklebust * release_open_intent - free up open intent resources 380834f2a4aSTrond Myklebust * @nd: pointer to nameidata 381834f2a4aSTrond Myklebust */ 382834f2a4aSTrond Myklebust void release_open_intent(struct nameidata *nd) 383834f2a4aSTrond Myklebust { 3840f7fc9e4SJosef "Jeff" Sipek if (nd->intent.open.file->f_path.dentry == NULL) 385834f2a4aSTrond Myklebust put_filp(nd->intent.open.file); 386834f2a4aSTrond Myklebust else 387834f2a4aSTrond Myklebust fput(nd->intent.open.file); 388834f2a4aSTrond Myklebust } 389834f2a4aSTrond Myklebust 390bcdc5e01SIan Kent static inline struct dentry * 391bcdc5e01SIan Kent do_revalidate(struct dentry *dentry, struct nameidata *nd) 392bcdc5e01SIan Kent { 393bcdc5e01SIan Kent int status = dentry->d_op->d_revalidate(dentry, nd); 394bcdc5e01SIan Kent if (unlikely(status <= 0)) { 395bcdc5e01SIan Kent /* 396bcdc5e01SIan Kent * The dentry failed validation. 397bcdc5e01SIan Kent * If d_revalidate returned 0 attempt to invalidate 398bcdc5e01SIan Kent * the dentry otherwise d_revalidate is asking us 399bcdc5e01SIan Kent * to return a fail status. 400bcdc5e01SIan Kent */ 401bcdc5e01SIan Kent if (!status) { 402bcdc5e01SIan Kent if (!d_invalidate(dentry)) { 403bcdc5e01SIan Kent dput(dentry); 404bcdc5e01SIan Kent dentry = NULL; 405bcdc5e01SIan Kent } 406bcdc5e01SIan Kent } else { 407bcdc5e01SIan Kent dput(dentry); 408bcdc5e01SIan Kent dentry = ERR_PTR(status); 409bcdc5e01SIan Kent } 410bcdc5e01SIan Kent } 411bcdc5e01SIan Kent return dentry; 412bcdc5e01SIan Kent } 413bcdc5e01SIan Kent 4141da177e4SLinus Torvalds /* 4151da177e4SLinus Torvalds * Internal lookup() using the new generic dcache. 4161da177e4SLinus Torvalds * SMP-safe 4171da177e4SLinus Torvalds */ 4181da177e4SLinus Torvalds static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) 4191da177e4SLinus Torvalds { 4201da177e4SLinus Torvalds struct dentry * dentry = __d_lookup(parent, name); 4211da177e4SLinus Torvalds 4221da177e4SLinus Torvalds /* lockess __d_lookup may fail due to concurrent d_move() 4231da177e4SLinus Torvalds * in some unrelated directory, so try with d_lookup 4241da177e4SLinus Torvalds */ 4251da177e4SLinus Torvalds if (!dentry) 4261da177e4SLinus Torvalds dentry = d_lookup(parent, name); 4271da177e4SLinus Torvalds 428bcdc5e01SIan Kent if (dentry && dentry->d_op && dentry->d_op->d_revalidate) 429bcdc5e01SIan Kent dentry = do_revalidate(dentry, nd); 430bcdc5e01SIan Kent 4311da177e4SLinus Torvalds return dentry; 4321da177e4SLinus Torvalds } 4331da177e4SLinus Torvalds 4341da177e4SLinus Torvalds /* 4351da177e4SLinus Torvalds * Short-cut version of permission(), for calling by 4361da177e4SLinus Torvalds * path_walk(), when dcache lock is held. Combines parts 4371da177e4SLinus Torvalds * of permission() and generic_permission(), and tests ONLY for 4381da177e4SLinus Torvalds * MAY_EXEC permission. 4391da177e4SLinus Torvalds * 4401da177e4SLinus Torvalds * If appropriate, check DAC only. If not appropriate, or 4411da177e4SLinus Torvalds * short-cut DAC fails, then call permission() to do more 4421da177e4SLinus Torvalds * complete permission check. 4431da177e4SLinus Torvalds */ 444858119e1SArjan van de Ven static int exec_permission_lite(struct inode *inode, 4451da177e4SLinus Torvalds struct nameidata *nd) 4461da177e4SLinus Torvalds { 4471da177e4SLinus Torvalds umode_t mode = inode->i_mode; 4481da177e4SLinus Torvalds 4491da177e4SLinus Torvalds if (inode->i_op && inode->i_op->permission) 4501da177e4SLinus Torvalds return -EAGAIN; 4511da177e4SLinus Torvalds 4521da177e4SLinus Torvalds if (current->fsuid == inode->i_uid) 4531da177e4SLinus Torvalds mode >>= 6; 4541da177e4SLinus Torvalds else if (in_group_p(inode->i_gid)) 4551da177e4SLinus Torvalds mode >>= 3; 4561da177e4SLinus Torvalds 4571da177e4SLinus Torvalds if (mode & MAY_EXEC) 4581da177e4SLinus Torvalds goto ok; 4591da177e4SLinus Torvalds 4601da177e4SLinus Torvalds if ((inode->i_mode & S_IXUGO) && capable(CAP_DAC_OVERRIDE)) 4611da177e4SLinus Torvalds goto ok; 4621da177e4SLinus Torvalds 4631da177e4SLinus Torvalds if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_OVERRIDE)) 4641da177e4SLinus Torvalds goto ok; 4651da177e4SLinus Torvalds 4661da177e4SLinus Torvalds if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_READ_SEARCH)) 4671da177e4SLinus Torvalds goto ok; 4681da177e4SLinus Torvalds 4691da177e4SLinus Torvalds return -EACCES; 4701da177e4SLinus Torvalds ok: 4711da177e4SLinus Torvalds return security_inode_permission(inode, MAY_EXEC, nd); 4721da177e4SLinus Torvalds } 4731da177e4SLinus Torvalds 4741da177e4SLinus Torvalds /* 4751da177e4SLinus Torvalds * This is called when everything else fails, and we actually have 4761da177e4SLinus Torvalds * to go to the low-level filesystem to find out what we should do.. 4771da177e4SLinus Torvalds * 4781da177e4SLinus Torvalds * We get the directory semaphore, and after getting that we also 4791da177e4SLinus Torvalds * make sure that nobody added the entry to the dcache in the meantime.. 4801da177e4SLinus Torvalds * SMP-safe 4811da177e4SLinus Torvalds */ 4821da177e4SLinus Torvalds static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) 4831da177e4SLinus Torvalds { 4841da177e4SLinus Torvalds struct dentry * result; 4851da177e4SLinus Torvalds struct inode *dir = parent->d_inode; 4861da177e4SLinus Torvalds 4871b1dcc1bSJes Sorensen mutex_lock(&dir->i_mutex); 4881da177e4SLinus Torvalds /* 4891da177e4SLinus Torvalds * First re-do the cached lookup just in case it was created 4901da177e4SLinus Torvalds * while we waited for the directory semaphore.. 4911da177e4SLinus Torvalds * 4921da177e4SLinus Torvalds * FIXME! This could use version numbering or similar to 4931da177e4SLinus Torvalds * avoid unnecessary cache lookups. 4941da177e4SLinus Torvalds * 4951da177e4SLinus Torvalds * The "dcache_lock" is purely to protect the RCU list walker 4961da177e4SLinus Torvalds * from concurrent renames at this point (we mustn't get false 4971da177e4SLinus Torvalds * negatives from the RCU list walk here, unlike the optimistic 4981da177e4SLinus Torvalds * fast walk). 4991da177e4SLinus Torvalds * 5001da177e4SLinus Torvalds * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup 5011da177e4SLinus Torvalds */ 5021da177e4SLinus Torvalds result = d_lookup(parent, name); 5031da177e4SLinus Torvalds if (!result) { 5041da177e4SLinus Torvalds struct dentry * dentry = d_alloc(parent, name); 5051da177e4SLinus Torvalds result = ERR_PTR(-ENOMEM); 5061da177e4SLinus Torvalds if (dentry) { 5071da177e4SLinus Torvalds result = dir->i_op->lookup(dir, dentry, nd); 5081da177e4SLinus Torvalds if (result) 5091da177e4SLinus Torvalds dput(dentry); 5101da177e4SLinus Torvalds else 5111da177e4SLinus Torvalds result = dentry; 5121da177e4SLinus Torvalds } 5131b1dcc1bSJes Sorensen mutex_unlock(&dir->i_mutex); 5141da177e4SLinus Torvalds return result; 5151da177e4SLinus Torvalds } 5161da177e4SLinus Torvalds 5171da177e4SLinus Torvalds /* 5181da177e4SLinus Torvalds * Uhhuh! Nasty case: the cache was re-populated while 5191da177e4SLinus Torvalds * we waited on the semaphore. Need to revalidate. 5201da177e4SLinus Torvalds */ 5211b1dcc1bSJes Sorensen mutex_unlock(&dir->i_mutex); 5221da177e4SLinus Torvalds if (result->d_op && result->d_op->d_revalidate) { 523bcdc5e01SIan Kent result = do_revalidate(result, nd); 524bcdc5e01SIan Kent if (!result) 5251da177e4SLinus Torvalds result = ERR_PTR(-ENOENT); 5261da177e4SLinus Torvalds } 5271da177e4SLinus Torvalds return result; 5281da177e4SLinus Torvalds } 5291da177e4SLinus Torvalds 5301da177e4SLinus Torvalds static int __emul_lookup_dentry(const char *, struct nameidata *); 5311da177e4SLinus Torvalds 5321da177e4SLinus Torvalds /* SMP-safe */ 533f1662356SArjan van de Ven static __always_inline int 5341da177e4SLinus Torvalds walk_init_root(const char *name, struct nameidata *nd) 5351da177e4SLinus Torvalds { 536e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 537e518ddb7SAndreas Mohr 538e518ddb7SAndreas Mohr read_lock(&fs->lock); 539e518ddb7SAndreas Mohr if (fs->altroot && !(nd->flags & LOOKUP_NOALT)) { 5404ac91378SJan Blunck nd->path.mnt = mntget(fs->altrootmnt); 5414ac91378SJan Blunck nd->path.dentry = dget(fs->altroot); 542e518ddb7SAndreas Mohr read_unlock(&fs->lock); 5431da177e4SLinus Torvalds if (__emul_lookup_dentry(name,nd)) 5441da177e4SLinus Torvalds return 0; 545e518ddb7SAndreas Mohr read_lock(&fs->lock); 5461da177e4SLinus Torvalds } 5474ac91378SJan Blunck nd->path.mnt = mntget(fs->rootmnt); 5484ac91378SJan Blunck nd->path.dentry = dget(fs->root); 549e518ddb7SAndreas Mohr read_unlock(&fs->lock); 5501da177e4SLinus Torvalds return 1; 5511da177e4SLinus Torvalds } 5521da177e4SLinus Torvalds 553f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 5541da177e4SLinus Torvalds { 5551da177e4SLinus Torvalds int res = 0; 5561da177e4SLinus Torvalds char *name; 5571da177e4SLinus Torvalds if (IS_ERR(link)) 5581da177e4SLinus Torvalds goto fail; 5591da177e4SLinus Torvalds 5601da177e4SLinus Torvalds if (*link == '/') { 5611d957f9bSJan Blunck path_put(&nd->path); 5621da177e4SLinus Torvalds if (!walk_init_root(link, nd)) 5631da177e4SLinus Torvalds /* weird __emul_prefix() stuff did it */ 5641da177e4SLinus Torvalds goto out; 5651da177e4SLinus Torvalds } 5661da177e4SLinus Torvalds res = link_path_walk(link, nd); 5671da177e4SLinus Torvalds out: 5681da177e4SLinus Torvalds if (nd->depth || res || nd->last_type!=LAST_NORM) 5691da177e4SLinus Torvalds return res; 5701da177e4SLinus Torvalds /* 5711da177e4SLinus Torvalds * If it is an iterative symlinks resolution in open_namei() we 5721da177e4SLinus Torvalds * have to copy the last component. And all that crap because of 5731da177e4SLinus Torvalds * bloody create() on broken symlinks. Furrfu... 5741da177e4SLinus Torvalds */ 5751da177e4SLinus Torvalds name = __getname(); 5761da177e4SLinus Torvalds if (unlikely(!name)) { 5771d957f9bSJan Blunck path_put(&nd->path); 5781da177e4SLinus Torvalds return -ENOMEM; 5791da177e4SLinus Torvalds } 5801da177e4SLinus Torvalds strcpy(name, nd->last.name); 5811da177e4SLinus Torvalds nd->last.name = name; 5821da177e4SLinus Torvalds return 0; 5831da177e4SLinus Torvalds fail: 5841d957f9bSJan Blunck path_put(&nd->path); 5851da177e4SLinus Torvalds return PTR_ERR(link); 5861da177e4SLinus Torvalds } 5871da177e4SLinus Torvalds 5881d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 589051d3812SIan Kent { 590051d3812SIan Kent dput(path->dentry); 5914ac91378SJan Blunck if (path->mnt != nd->path.mnt) 592051d3812SIan Kent mntput(path->mnt); 593051d3812SIan Kent } 594051d3812SIan Kent 595051d3812SIan Kent static inline void path_to_nameidata(struct path *path, struct nameidata *nd) 596051d3812SIan Kent { 5974ac91378SJan Blunck dput(nd->path.dentry); 5984ac91378SJan Blunck if (nd->path.mnt != path->mnt) 5994ac91378SJan Blunck mntput(nd->path.mnt); 6004ac91378SJan Blunck nd->path.mnt = path->mnt; 6014ac91378SJan Blunck nd->path.dentry = path->dentry; 602051d3812SIan Kent } 603051d3812SIan Kent 604f1662356SArjan van de Ven static __always_inline int __do_follow_link(struct path *path, struct nameidata *nd) 6051da177e4SLinus Torvalds { 6061da177e4SLinus Torvalds int error; 607cc314eefSLinus Torvalds void *cookie; 608cd4e91d3SAl Viro struct dentry *dentry = path->dentry; 6091da177e4SLinus Torvalds 610d671a1cbSAl Viro touch_atime(path->mnt, dentry); 6111da177e4SLinus Torvalds nd_set_link(nd, NULL); 612cd4e91d3SAl Viro 6134ac91378SJan Blunck if (path->mnt != nd->path.mnt) { 614051d3812SIan Kent path_to_nameidata(path, nd); 615051d3812SIan Kent dget(dentry); 616051d3812SIan Kent } 617cd4e91d3SAl Viro mntget(path->mnt); 618cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, nd); 619cc314eefSLinus Torvalds error = PTR_ERR(cookie); 620cc314eefSLinus Torvalds if (!IS_ERR(cookie)) { 6211da177e4SLinus Torvalds char *s = nd_get_link(nd); 622cc314eefSLinus Torvalds error = 0; 6231da177e4SLinus Torvalds if (s) 6241da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 6251da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 626cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, nd, cookie); 6271da177e4SLinus Torvalds } 628cd4e91d3SAl Viro dput(dentry); 629cd4e91d3SAl Viro mntput(path->mnt); 6301da177e4SLinus Torvalds 6311da177e4SLinus Torvalds return error; 6321da177e4SLinus Torvalds } 6331da177e4SLinus Torvalds 6341da177e4SLinus Torvalds /* 6351da177e4SLinus Torvalds * This limits recursive symlink follows to 8, while 6361da177e4SLinus Torvalds * limiting consecutive symlinks to 40. 6371da177e4SLinus Torvalds * 6381da177e4SLinus Torvalds * Without that kind of total limit, nasty chains of consecutive 6391da177e4SLinus Torvalds * symlinks can cause almost arbitrarily long lookups. 6401da177e4SLinus Torvalds */ 64190ebe565SAl Viro static inline int do_follow_link(struct path *path, struct nameidata *nd) 6421da177e4SLinus Torvalds { 6431da177e4SLinus Torvalds int err = -ELOOP; 6441da177e4SLinus Torvalds if (current->link_count >= MAX_NESTED_LINKS) 6451da177e4SLinus Torvalds goto loop; 6461da177e4SLinus Torvalds if (current->total_link_count >= 40) 6471da177e4SLinus Torvalds goto loop; 6481da177e4SLinus Torvalds BUG_ON(nd->depth >= MAX_NESTED_LINKS); 6491da177e4SLinus Torvalds cond_resched(); 65090ebe565SAl Viro err = security_inode_follow_link(path->dentry, nd); 6511da177e4SLinus Torvalds if (err) 6521da177e4SLinus Torvalds goto loop; 6531da177e4SLinus Torvalds current->link_count++; 6541da177e4SLinus Torvalds current->total_link_count++; 6551da177e4SLinus Torvalds nd->depth++; 656cd4e91d3SAl Viro err = __do_follow_link(path, nd); 6571da177e4SLinus Torvalds current->link_count--; 6581da177e4SLinus Torvalds nd->depth--; 6591da177e4SLinus Torvalds return err; 6601da177e4SLinus Torvalds loop: 6611d957f9bSJan Blunck path_put_conditional(path, nd); 6621d957f9bSJan Blunck path_put(&nd->path); 6631da177e4SLinus Torvalds return err; 6641da177e4SLinus Torvalds } 6651da177e4SLinus Torvalds 6661da177e4SLinus Torvalds int follow_up(struct vfsmount **mnt, struct dentry **dentry) 6671da177e4SLinus Torvalds { 6681da177e4SLinus Torvalds struct vfsmount *parent; 6691da177e4SLinus Torvalds struct dentry *mountpoint; 6701da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 6711da177e4SLinus Torvalds parent=(*mnt)->mnt_parent; 6721da177e4SLinus Torvalds if (parent == *mnt) { 6731da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 6741da177e4SLinus Torvalds return 0; 6751da177e4SLinus Torvalds } 6761da177e4SLinus Torvalds mntget(parent); 6771da177e4SLinus Torvalds mountpoint=dget((*mnt)->mnt_mountpoint); 6781da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 6791da177e4SLinus Torvalds dput(*dentry); 6801da177e4SLinus Torvalds *dentry = mountpoint; 6811da177e4SLinus Torvalds mntput(*mnt); 6821da177e4SLinus Torvalds *mnt = parent; 6831da177e4SLinus Torvalds return 1; 6841da177e4SLinus Torvalds } 6851da177e4SLinus Torvalds 6861da177e4SLinus Torvalds /* no need for dcache_lock, as serialization is taken care in 6871da177e4SLinus Torvalds * namespace.c 6881da177e4SLinus Torvalds */ 689463ffb2eSAl Viro static int __follow_mount(struct path *path) 690463ffb2eSAl Viro { 691463ffb2eSAl Viro int res = 0; 692463ffb2eSAl Viro while (d_mountpoint(path->dentry)) { 693463ffb2eSAl Viro struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry); 694463ffb2eSAl Viro if (!mounted) 695463ffb2eSAl Viro break; 696463ffb2eSAl Viro dput(path->dentry); 697463ffb2eSAl Viro if (res) 698463ffb2eSAl Viro mntput(path->mnt); 699463ffb2eSAl Viro path->mnt = mounted; 700463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 701463ffb2eSAl Viro res = 1; 702463ffb2eSAl Viro } 703463ffb2eSAl Viro return res; 704463ffb2eSAl Viro } 705463ffb2eSAl Viro 70658c465ebSAl Viro static void follow_mount(struct vfsmount **mnt, struct dentry **dentry) 7071da177e4SLinus Torvalds { 7081da177e4SLinus Torvalds while (d_mountpoint(*dentry)) { 7091da177e4SLinus Torvalds struct vfsmount *mounted = lookup_mnt(*mnt, *dentry); 7101da177e4SLinus Torvalds if (!mounted) 7111da177e4SLinus Torvalds break; 71258c465ebSAl Viro dput(*dentry); 7131da177e4SLinus Torvalds mntput(*mnt); 7141da177e4SLinus Torvalds *mnt = mounted; 7151da177e4SLinus Torvalds *dentry = dget(mounted->mnt_root); 7161da177e4SLinus Torvalds } 7171da177e4SLinus Torvalds } 7181da177e4SLinus Torvalds 7191da177e4SLinus Torvalds /* no need for dcache_lock, as serialization is taken care in 7201da177e4SLinus Torvalds * namespace.c 7211da177e4SLinus Torvalds */ 722e13b210fSAl Viro int follow_down(struct vfsmount **mnt, struct dentry **dentry) 7231da177e4SLinus Torvalds { 7241da177e4SLinus Torvalds struct vfsmount *mounted; 7251da177e4SLinus Torvalds 7261da177e4SLinus Torvalds mounted = lookup_mnt(*mnt, *dentry); 7271da177e4SLinus Torvalds if (mounted) { 728e13b210fSAl Viro dput(*dentry); 7291da177e4SLinus Torvalds mntput(*mnt); 7301da177e4SLinus Torvalds *mnt = mounted; 7311da177e4SLinus Torvalds *dentry = dget(mounted->mnt_root); 7321da177e4SLinus Torvalds return 1; 7331da177e4SLinus Torvalds } 7341da177e4SLinus Torvalds return 0; 7351da177e4SLinus Torvalds } 7361da177e4SLinus Torvalds 737f1662356SArjan van de Ven static __always_inline void follow_dotdot(struct nameidata *nd) 7381da177e4SLinus Torvalds { 739e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 740e518ddb7SAndreas Mohr 7411da177e4SLinus Torvalds while(1) { 7421da177e4SLinus Torvalds struct vfsmount *parent; 7434ac91378SJan Blunck struct dentry *old = nd->path.dentry; 7441da177e4SLinus Torvalds 745e518ddb7SAndreas Mohr read_lock(&fs->lock); 7464ac91378SJan Blunck if (nd->path.dentry == fs->root && 7474ac91378SJan Blunck nd->path.mnt == fs->rootmnt) { 748e518ddb7SAndreas Mohr read_unlock(&fs->lock); 7491da177e4SLinus Torvalds break; 7501da177e4SLinus Torvalds } 751e518ddb7SAndreas Mohr read_unlock(&fs->lock); 7521da177e4SLinus Torvalds spin_lock(&dcache_lock); 7534ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 7544ac91378SJan Blunck nd->path.dentry = dget(nd->path.dentry->d_parent); 7551da177e4SLinus Torvalds spin_unlock(&dcache_lock); 7561da177e4SLinus Torvalds dput(old); 7571da177e4SLinus Torvalds break; 7581da177e4SLinus Torvalds } 7591da177e4SLinus Torvalds spin_unlock(&dcache_lock); 7601da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 7614ac91378SJan Blunck parent = nd->path.mnt->mnt_parent; 7624ac91378SJan Blunck if (parent == nd->path.mnt) { 7631da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7641da177e4SLinus Torvalds break; 7651da177e4SLinus Torvalds } 7661da177e4SLinus Torvalds mntget(parent); 7674ac91378SJan Blunck nd->path.dentry = dget(nd->path.mnt->mnt_mountpoint); 7681da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7691da177e4SLinus Torvalds dput(old); 7704ac91378SJan Blunck mntput(nd->path.mnt); 7714ac91378SJan Blunck nd->path.mnt = parent; 7721da177e4SLinus Torvalds } 7734ac91378SJan Blunck follow_mount(&nd->path.mnt, &nd->path.dentry); 7741da177e4SLinus Torvalds } 7751da177e4SLinus Torvalds 7761da177e4SLinus Torvalds /* 7771da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 7781da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 7791da177e4SLinus Torvalds * It _is_ time-critical. 7801da177e4SLinus Torvalds */ 7811da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 7821da177e4SLinus Torvalds struct path *path) 7831da177e4SLinus Torvalds { 7844ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 7854ac91378SJan Blunck struct dentry *dentry = __d_lookup(nd->path.dentry, name); 7861da177e4SLinus Torvalds 7871da177e4SLinus Torvalds if (!dentry) 7881da177e4SLinus Torvalds goto need_lookup; 7891da177e4SLinus Torvalds if (dentry->d_op && dentry->d_op->d_revalidate) 7901da177e4SLinus Torvalds goto need_revalidate; 7911da177e4SLinus Torvalds done: 7921da177e4SLinus Torvalds path->mnt = mnt; 7931da177e4SLinus Torvalds path->dentry = dentry; 794634ee701SAl Viro __follow_mount(path); 7951da177e4SLinus Torvalds return 0; 7961da177e4SLinus Torvalds 7971da177e4SLinus Torvalds need_lookup: 7984ac91378SJan Blunck dentry = real_lookup(nd->path.dentry, name, nd); 7991da177e4SLinus Torvalds if (IS_ERR(dentry)) 8001da177e4SLinus Torvalds goto fail; 8011da177e4SLinus Torvalds goto done; 8021da177e4SLinus Torvalds 8031da177e4SLinus Torvalds need_revalidate: 804bcdc5e01SIan Kent dentry = do_revalidate(dentry, nd); 805bcdc5e01SIan Kent if (!dentry) 8061da177e4SLinus Torvalds goto need_lookup; 807bcdc5e01SIan Kent if (IS_ERR(dentry)) 808bcdc5e01SIan Kent goto fail; 809bcdc5e01SIan Kent goto done; 8101da177e4SLinus Torvalds 8111da177e4SLinus Torvalds fail: 8121da177e4SLinus Torvalds return PTR_ERR(dentry); 8131da177e4SLinus Torvalds } 8141da177e4SLinus Torvalds 8151da177e4SLinus Torvalds /* 8161da177e4SLinus Torvalds * Name resolution. 817ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 818ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 8191da177e4SLinus Torvalds * 820ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 821ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 8221da177e4SLinus Torvalds */ 823fc9b52cdSHarvey Harrison static int __link_path_walk(const char *name, struct nameidata *nd) 8241da177e4SLinus Torvalds { 8251da177e4SLinus Torvalds struct path next; 8261da177e4SLinus Torvalds struct inode *inode; 8271da177e4SLinus Torvalds int err; 8281da177e4SLinus Torvalds unsigned int lookup_flags = nd->flags; 8291da177e4SLinus Torvalds 8301da177e4SLinus Torvalds while (*name=='/') 8311da177e4SLinus Torvalds name++; 8321da177e4SLinus Torvalds if (!*name) 8331da177e4SLinus Torvalds goto return_reval; 8341da177e4SLinus Torvalds 8354ac91378SJan Blunck inode = nd->path.dentry->d_inode; 8361da177e4SLinus Torvalds if (nd->depth) 837f55eab82STrond Myklebust lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE); 8381da177e4SLinus Torvalds 8391da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 8401da177e4SLinus Torvalds for(;;) { 8411da177e4SLinus Torvalds unsigned long hash; 8421da177e4SLinus Torvalds struct qstr this; 8431da177e4SLinus Torvalds unsigned int c; 8441da177e4SLinus Torvalds 845cdce5d6bSTrond Myklebust nd->flags |= LOOKUP_CONTINUE; 8461da177e4SLinus Torvalds err = exec_permission_lite(inode, nd); 847e4543eddSChristoph Hellwig if (err == -EAGAIN) 848e4543eddSChristoph Hellwig err = vfs_permission(nd, MAY_EXEC); 8491da177e4SLinus Torvalds if (err) 8501da177e4SLinus Torvalds break; 8511da177e4SLinus Torvalds 8521da177e4SLinus Torvalds this.name = name; 8531da177e4SLinus Torvalds c = *(const unsigned char *)name; 8541da177e4SLinus Torvalds 8551da177e4SLinus Torvalds hash = init_name_hash(); 8561da177e4SLinus Torvalds do { 8571da177e4SLinus Torvalds name++; 8581da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 8591da177e4SLinus Torvalds c = *(const unsigned char *)name; 8601da177e4SLinus Torvalds } while (c && (c != '/')); 8611da177e4SLinus Torvalds this.len = name - (const char *) this.name; 8621da177e4SLinus Torvalds this.hash = end_name_hash(hash); 8631da177e4SLinus Torvalds 8641da177e4SLinus Torvalds /* remove trailing slashes? */ 8651da177e4SLinus Torvalds if (!c) 8661da177e4SLinus Torvalds goto last_component; 8671da177e4SLinus Torvalds while (*++name == '/'); 8681da177e4SLinus Torvalds if (!*name) 8691da177e4SLinus Torvalds goto last_with_slashes; 8701da177e4SLinus Torvalds 8711da177e4SLinus Torvalds /* 8721da177e4SLinus Torvalds * "." and ".." are special - ".." especially so because it has 8731da177e4SLinus Torvalds * to be able to know about the current root directory and 8741da177e4SLinus Torvalds * parent relationships. 8751da177e4SLinus Torvalds */ 8761da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 8771da177e4SLinus Torvalds default: 8781da177e4SLinus Torvalds break; 8791da177e4SLinus Torvalds case 2: 8801da177e4SLinus Torvalds if (this.name[1] != '.') 8811da177e4SLinus Torvalds break; 88258c465ebSAl Viro follow_dotdot(nd); 8834ac91378SJan Blunck inode = nd->path.dentry->d_inode; 8841da177e4SLinus Torvalds /* fallthrough */ 8851da177e4SLinus Torvalds case 1: 8861da177e4SLinus Torvalds continue; 8871da177e4SLinus Torvalds } 8881da177e4SLinus Torvalds /* 8891da177e4SLinus Torvalds * See if the low-level filesystem might want 8901da177e4SLinus Torvalds * to use its own hash.. 8911da177e4SLinus Torvalds */ 8924ac91378SJan Blunck if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { 8934ac91378SJan Blunck err = nd->path.dentry->d_op->d_hash(nd->path.dentry, 8944ac91378SJan Blunck &this); 8951da177e4SLinus Torvalds if (err < 0) 8961da177e4SLinus Torvalds break; 8971da177e4SLinus Torvalds } 8981da177e4SLinus Torvalds /* This does the actual lookups.. */ 8991da177e4SLinus Torvalds err = do_lookup(nd, &this, &next); 9001da177e4SLinus Torvalds if (err) 9011da177e4SLinus Torvalds break; 9021da177e4SLinus Torvalds 9031da177e4SLinus Torvalds err = -ENOENT; 9041da177e4SLinus Torvalds inode = next.dentry->d_inode; 9051da177e4SLinus Torvalds if (!inode) 9061da177e4SLinus Torvalds goto out_dput; 9071da177e4SLinus Torvalds err = -ENOTDIR; 9081da177e4SLinus Torvalds if (!inode->i_op) 9091da177e4SLinus Torvalds goto out_dput; 9101da177e4SLinus Torvalds 9111da177e4SLinus Torvalds if (inode->i_op->follow_link) { 91290ebe565SAl Viro err = do_follow_link(&next, nd); 9131da177e4SLinus Torvalds if (err) 9141da177e4SLinus Torvalds goto return_err; 9151da177e4SLinus Torvalds err = -ENOENT; 9164ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9171da177e4SLinus Torvalds if (!inode) 9181da177e4SLinus Torvalds break; 9191da177e4SLinus Torvalds err = -ENOTDIR; 9201da177e4SLinus Torvalds if (!inode->i_op) 9211da177e4SLinus Torvalds break; 92209dd17d3SMiklos Szeredi } else 92309dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 9241da177e4SLinus Torvalds err = -ENOTDIR; 9251da177e4SLinus Torvalds if (!inode->i_op->lookup) 9261da177e4SLinus Torvalds break; 9271da177e4SLinus Torvalds continue; 9281da177e4SLinus Torvalds /* here ends the main loop */ 9291da177e4SLinus Torvalds 9301da177e4SLinus Torvalds last_with_slashes: 9311da177e4SLinus Torvalds lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 9321da177e4SLinus Torvalds last_component: 933f55eab82STrond Myklebust /* Clear LOOKUP_CONTINUE iff it was previously unset */ 934f55eab82STrond Myklebust nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; 9351da177e4SLinus Torvalds if (lookup_flags & LOOKUP_PARENT) 9361da177e4SLinus Torvalds goto lookup_parent; 9371da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 9381da177e4SLinus Torvalds default: 9391da177e4SLinus Torvalds break; 9401da177e4SLinus Torvalds case 2: 9411da177e4SLinus Torvalds if (this.name[1] != '.') 9421da177e4SLinus Torvalds break; 94358c465ebSAl Viro follow_dotdot(nd); 9444ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9451da177e4SLinus Torvalds /* fallthrough */ 9461da177e4SLinus Torvalds case 1: 9471da177e4SLinus Torvalds goto return_reval; 9481da177e4SLinus Torvalds } 9494ac91378SJan Blunck if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { 9504ac91378SJan Blunck err = nd->path.dentry->d_op->d_hash(nd->path.dentry, 9514ac91378SJan Blunck &this); 9521da177e4SLinus Torvalds if (err < 0) 9531da177e4SLinus Torvalds break; 9541da177e4SLinus Torvalds } 9551da177e4SLinus Torvalds err = do_lookup(nd, &this, &next); 9561da177e4SLinus Torvalds if (err) 9571da177e4SLinus Torvalds break; 9581da177e4SLinus Torvalds inode = next.dentry->d_inode; 9591da177e4SLinus Torvalds if ((lookup_flags & LOOKUP_FOLLOW) 9601da177e4SLinus Torvalds && inode && inode->i_op && inode->i_op->follow_link) { 96190ebe565SAl Viro err = do_follow_link(&next, nd); 9621da177e4SLinus Torvalds if (err) 9631da177e4SLinus Torvalds goto return_err; 9644ac91378SJan Blunck inode = nd->path.dentry->d_inode; 96509dd17d3SMiklos Szeredi } else 96609dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 9671da177e4SLinus Torvalds err = -ENOENT; 9681da177e4SLinus Torvalds if (!inode) 9691da177e4SLinus Torvalds break; 9701da177e4SLinus Torvalds if (lookup_flags & LOOKUP_DIRECTORY) { 9711da177e4SLinus Torvalds err = -ENOTDIR; 9721da177e4SLinus Torvalds if (!inode->i_op || !inode->i_op->lookup) 9731da177e4SLinus Torvalds break; 9741da177e4SLinus Torvalds } 9751da177e4SLinus Torvalds goto return_base; 9761da177e4SLinus Torvalds lookup_parent: 9771da177e4SLinus Torvalds nd->last = this; 9781da177e4SLinus Torvalds nd->last_type = LAST_NORM; 9791da177e4SLinus Torvalds if (this.name[0] != '.') 9801da177e4SLinus Torvalds goto return_base; 9811da177e4SLinus Torvalds if (this.len == 1) 9821da177e4SLinus Torvalds nd->last_type = LAST_DOT; 9831da177e4SLinus Torvalds else if (this.len == 2 && this.name[1] == '.') 9841da177e4SLinus Torvalds nd->last_type = LAST_DOTDOT; 9851da177e4SLinus Torvalds else 9861da177e4SLinus Torvalds goto return_base; 9871da177e4SLinus Torvalds return_reval: 9881da177e4SLinus Torvalds /* 9891da177e4SLinus Torvalds * We bypassed the ordinary revalidation routines. 9901da177e4SLinus Torvalds * We may need to check the cached dentry for staleness. 9911da177e4SLinus Torvalds */ 9924ac91378SJan Blunck if (nd->path.dentry && nd->path.dentry->d_sb && 9934ac91378SJan Blunck (nd->path.dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) { 9941da177e4SLinus Torvalds err = -ESTALE; 9951da177e4SLinus Torvalds /* Note: we do not d_invalidate() */ 9964ac91378SJan Blunck if (!nd->path.dentry->d_op->d_revalidate( 9974ac91378SJan Blunck nd->path.dentry, nd)) 9981da177e4SLinus Torvalds break; 9991da177e4SLinus Torvalds } 10001da177e4SLinus Torvalds return_base: 10011da177e4SLinus Torvalds return 0; 10021da177e4SLinus Torvalds out_dput: 10031d957f9bSJan Blunck path_put_conditional(&next, nd); 10041da177e4SLinus Torvalds break; 10051da177e4SLinus Torvalds } 10061d957f9bSJan Blunck path_put(&nd->path); 10071da177e4SLinus Torvalds return_err: 10081da177e4SLinus Torvalds return err; 10091da177e4SLinus Torvalds } 10101da177e4SLinus Torvalds 10111da177e4SLinus Torvalds /* 10121da177e4SLinus Torvalds * Wrapper to retry pathname resolution whenever the underlying 10131da177e4SLinus Torvalds * file system returns an ESTALE. 10141da177e4SLinus Torvalds * 10151da177e4SLinus Torvalds * Retry the whole path once, forcing real lookup requests 10161da177e4SLinus Torvalds * instead of relying on the dcache. 10171da177e4SLinus Torvalds */ 1018fc9b52cdSHarvey Harrison static int link_path_walk(const char *name, struct nameidata *nd) 10191da177e4SLinus Torvalds { 10201da177e4SLinus Torvalds struct nameidata save = *nd; 10211da177e4SLinus Torvalds int result; 10221da177e4SLinus Torvalds 10231da177e4SLinus Torvalds /* make sure the stuff we saved doesn't go away */ 10244ac91378SJan Blunck dget(save.path.dentry); 10254ac91378SJan Blunck mntget(save.path.mnt); 10261da177e4SLinus Torvalds 10271da177e4SLinus Torvalds result = __link_path_walk(name, nd); 10281da177e4SLinus Torvalds if (result == -ESTALE) { 10291da177e4SLinus Torvalds *nd = save; 10304ac91378SJan Blunck dget(nd->path.dentry); 10314ac91378SJan Blunck mntget(nd->path.mnt); 10321da177e4SLinus Torvalds nd->flags |= LOOKUP_REVAL; 10331da177e4SLinus Torvalds result = __link_path_walk(name, nd); 10341da177e4SLinus Torvalds } 10351da177e4SLinus Torvalds 10364ac91378SJan Blunck dput(save.path.dentry); 10374ac91378SJan Blunck mntput(save.path.mnt); 10381da177e4SLinus Torvalds 10391da177e4SLinus Torvalds return result; 10401da177e4SLinus Torvalds } 10411da177e4SLinus Torvalds 1042fc9b52cdSHarvey Harrison static int path_walk(const char *name, struct nameidata *nd) 10431da177e4SLinus Torvalds { 10441da177e4SLinus Torvalds current->total_link_count = 0; 10451da177e4SLinus Torvalds return link_path_walk(name, nd); 10461da177e4SLinus Torvalds } 10471da177e4SLinus Torvalds 1048ea3834d9SPrasanna Meda /* 1049ea3834d9SPrasanna Meda * SMP-safe: Returns 1 and nd will have valid dentry and mnt, if 1050ea3834d9SPrasanna Meda * everything is done. Returns 0 and drops input nd, if lookup failed; 1051ea3834d9SPrasanna Meda */ 10521da177e4SLinus Torvalds static int __emul_lookup_dentry(const char *name, struct nameidata *nd) 10531da177e4SLinus Torvalds { 10541da177e4SLinus Torvalds if (path_walk(name, nd)) 10551da177e4SLinus Torvalds return 0; /* something went wrong... */ 10561da177e4SLinus Torvalds 10574ac91378SJan Blunck if (!nd->path.dentry->d_inode || 10584ac91378SJan Blunck S_ISDIR(nd->path.dentry->d_inode->i_mode)) { 10594ac91378SJan Blunck struct dentry *old_dentry = nd->path.dentry; 10604ac91378SJan Blunck struct vfsmount *old_mnt = nd->path.mnt; 10611da177e4SLinus Torvalds struct qstr last = nd->last; 10621da177e4SLinus Torvalds int last_type = nd->last_type; 1063e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 1064e518ddb7SAndreas Mohr 10651da177e4SLinus Torvalds /* 1066e518ddb7SAndreas Mohr * NAME was not found in alternate root or it's a directory. 1067e518ddb7SAndreas Mohr * Try to find it in the normal root: 10681da177e4SLinus Torvalds */ 10691da177e4SLinus Torvalds nd->last_type = LAST_ROOT; 1070e518ddb7SAndreas Mohr read_lock(&fs->lock); 10714ac91378SJan Blunck nd->path.mnt = mntget(fs->rootmnt); 10724ac91378SJan Blunck nd->path.dentry = dget(fs->root); 1073e518ddb7SAndreas Mohr read_unlock(&fs->lock); 10741da177e4SLinus Torvalds if (path_walk(name, nd) == 0) { 10754ac91378SJan Blunck if (nd->path.dentry->d_inode) { 10761da177e4SLinus Torvalds dput(old_dentry); 10771da177e4SLinus Torvalds mntput(old_mnt); 10781da177e4SLinus Torvalds return 1; 10791da177e4SLinus Torvalds } 10801d957f9bSJan Blunck path_put(&nd->path); 10811da177e4SLinus Torvalds } 10824ac91378SJan Blunck nd->path.dentry = old_dentry; 10834ac91378SJan Blunck nd->path.mnt = old_mnt; 10841da177e4SLinus Torvalds nd->last = last; 10851da177e4SLinus Torvalds nd->last_type = last_type; 10861da177e4SLinus Torvalds } 10871da177e4SLinus Torvalds return 1; 10881da177e4SLinus Torvalds } 10891da177e4SLinus Torvalds 10901da177e4SLinus Torvalds void set_fs_altroot(void) 10911da177e4SLinus Torvalds { 10921da177e4SLinus Torvalds char *emul = __emul_prefix(); 10931da177e4SLinus Torvalds struct nameidata nd; 10941da177e4SLinus Torvalds struct vfsmount *mnt = NULL, *oldmnt; 10951da177e4SLinus Torvalds struct dentry *dentry = NULL, *olddentry; 10961da177e4SLinus Torvalds int err; 1097e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 10981da177e4SLinus Torvalds 10991da177e4SLinus Torvalds if (!emul) 11001da177e4SLinus Torvalds goto set_it; 11011da177e4SLinus Torvalds err = path_lookup(emul, LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_NOALT, &nd); 11021da177e4SLinus Torvalds if (!err) { 11034ac91378SJan Blunck mnt = nd.path.mnt; 11044ac91378SJan Blunck dentry = nd.path.dentry; 11051da177e4SLinus Torvalds } 11061da177e4SLinus Torvalds set_it: 1107e518ddb7SAndreas Mohr write_lock(&fs->lock); 1108e518ddb7SAndreas Mohr oldmnt = fs->altrootmnt; 1109e518ddb7SAndreas Mohr olddentry = fs->altroot; 1110e518ddb7SAndreas Mohr fs->altrootmnt = mnt; 1111e518ddb7SAndreas Mohr fs->altroot = dentry; 1112e518ddb7SAndreas Mohr write_unlock(&fs->lock); 11131da177e4SLinus Torvalds if (olddentry) { 11141da177e4SLinus Torvalds dput(olddentry); 11151da177e4SLinus Torvalds mntput(oldmnt); 11161da177e4SLinus Torvalds } 11171da177e4SLinus Torvalds } 11181da177e4SLinus Torvalds 1119ea3834d9SPrasanna Meda /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1120fc9b52cdSHarvey Harrison static int do_path_lookup(int dfd, const char *name, 11215590ff0dSUlrich Drepper unsigned int flags, struct nameidata *nd) 11221da177e4SLinus Torvalds { 1123ea3834d9SPrasanna Meda int retval = 0; 1124170aa3d0SUlrich Drepper int fput_needed; 1125170aa3d0SUlrich Drepper struct file *file; 1126e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 11271da177e4SLinus Torvalds 11281da177e4SLinus Torvalds nd->last_type = LAST_ROOT; /* if there are only slashes... */ 11291da177e4SLinus Torvalds nd->flags = flags; 11301da177e4SLinus Torvalds nd->depth = 0; 11311da177e4SLinus Torvalds 11321da177e4SLinus Torvalds if (*name=='/') { 1133e518ddb7SAndreas Mohr read_lock(&fs->lock); 1134e518ddb7SAndreas Mohr if (fs->altroot && !(nd->flags & LOOKUP_NOALT)) { 11354ac91378SJan Blunck nd->path.mnt = mntget(fs->altrootmnt); 11364ac91378SJan Blunck nd->path.dentry = dget(fs->altroot); 1137e518ddb7SAndreas Mohr read_unlock(&fs->lock); 11381da177e4SLinus Torvalds if (__emul_lookup_dentry(name,nd)) 1139ea3834d9SPrasanna Meda goto out; /* found in altroot */ 1140e518ddb7SAndreas Mohr read_lock(&fs->lock); 11411da177e4SLinus Torvalds } 11424ac91378SJan Blunck nd->path.mnt = mntget(fs->rootmnt); 11434ac91378SJan Blunck nd->path.dentry = dget(fs->root); 1144e518ddb7SAndreas Mohr read_unlock(&fs->lock); 11455590ff0dSUlrich Drepper } else if (dfd == AT_FDCWD) { 1146e518ddb7SAndreas Mohr read_lock(&fs->lock); 11474ac91378SJan Blunck nd->path.mnt = mntget(fs->pwdmnt); 11484ac91378SJan Blunck nd->path.dentry = dget(fs->pwd); 1149e518ddb7SAndreas Mohr read_unlock(&fs->lock); 11505590ff0dSUlrich Drepper } else { 11515590ff0dSUlrich Drepper struct dentry *dentry; 11525590ff0dSUlrich Drepper 11535590ff0dSUlrich Drepper file = fget_light(dfd, &fput_needed); 11545590ff0dSUlrich Drepper retval = -EBADF; 1155170aa3d0SUlrich Drepper if (!file) 11566d09bb62STrond Myklebust goto out_fail; 11575590ff0dSUlrich Drepper 11580f7fc9e4SJosef "Jeff" Sipek dentry = file->f_path.dentry; 11595590ff0dSUlrich Drepper 11605590ff0dSUlrich Drepper retval = -ENOTDIR; 1161170aa3d0SUlrich Drepper if (!S_ISDIR(dentry->d_inode->i_mode)) 11626d09bb62STrond Myklebust goto fput_fail; 11635590ff0dSUlrich Drepper 11645590ff0dSUlrich Drepper retval = file_permission(file, MAY_EXEC); 1165170aa3d0SUlrich Drepper if (retval) 11666d09bb62STrond Myklebust goto fput_fail; 11675590ff0dSUlrich Drepper 11684ac91378SJan Blunck nd->path.mnt = mntget(file->f_path.mnt); 11694ac91378SJan Blunck nd->path.dentry = dget(dentry); 11705590ff0dSUlrich Drepper 11715590ff0dSUlrich Drepper fput_light(file, fput_needed); 11721da177e4SLinus Torvalds } 11732dfdd266SJosef 'Jeff' Sipek 11742dfdd266SJosef 'Jeff' Sipek retval = path_walk(name, nd); 1175ea3834d9SPrasanna Meda out: 11764ac91378SJan Blunck if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && 11774ac91378SJan Blunck nd->path.dentry->d_inode)) 11784ac91378SJan Blunck audit_inode(name, nd->path.dentry); 11796d09bb62STrond Myklebust out_fail: 1180170aa3d0SUlrich Drepper return retval; 1181170aa3d0SUlrich Drepper 11826d09bb62STrond Myklebust fput_fail: 1183170aa3d0SUlrich Drepper fput_light(file, fput_needed); 11846d09bb62STrond Myklebust goto out_fail; 11851da177e4SLinus Torvalds } 11861da177e4SLinus Torvalds 1187fc9b52cdSHarvey Harrison int path_lookup(const char *name, unsigned int flags, 11885590ff0dSUlrich Drepper struct nameidata *nd) 11895590ff0dSUlrich Drepper { 11905590ff0dSUlrich Drepper return do_path_lookup(AT_FDCWD, name, flags, nd); 11915590ff0dSUlrich Drepper } 11925590ff0dSUlrich Drepper 119316f18200SJosef 'Jeff' Sipek /** 119416f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 119516f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 119616f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 119716f18200SJosef 'Jeff' Sipek * @name: pointer to file name 119816f18200SJosef 'Jeff' Sipek * @flags: lookup flags 119916f18200SJosef 'Jeff' Sipek * @nd: pointer to nameidata 120016f18200SJosef 'Jeff' Sipek */ 120116f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 120216f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 120316f18200SJosef 'Jeff' Sipek struct nameidata *nd) 120416f18200SJosef 'Jeff' Sipek { 120516f18200SJosef 'Jeff' Sipek int retval; 120616f18200SJosef 'Jeff' Sipek 120716f18200SJosef 'Jeff' Sipek /* same as do_path_lookup */ 120816f18200SJosef 'Jeff' Sipek nd->last_type = LAST_ROOT; 120916f18200SJosef 'Jeff' Sipek nd->flags = flags; 121016f18200SJosef 'Jeff' Sipek nd->depth = 0; 121116f18200SJosef 'Jeff' Sipek 12124ac91378SJan Blunck nd->path.mnt = mntget(mnt); 12134ac91378SJan Blunck nd->path.dentry = dget(dentry); 121416f18200SJosef 'Jeff' Sipek 121516f18200SJosef 'Jeff' Sipek retval = path_walk(name, nd); 12164ac91378SJan Blunck if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && 12174ac91378SJan Blunck nd->path.dentry->d_inode)) 12184ac91378SJan Blunck audit_inode(name, nd->path.dentry); 121916f18200SJosef 'Jeff' Sipek 122016f18200SJosef 'Jeff' Sipek return retval; 122116f18200SJosef 'Jeff' Sipek 122216f18200SJosef 'Jeff' Sipek } 122316f18200SJosef 'Jeff' Sipek 12245590ff0dSUlrich Drepper static int __path_lookup_intent_open(int dfd, const char *name, 12255590ff0dSUlrich Drepper unsigned int lookup_flags, struct nameidata *nd, 12265590ff0dSUlrich Drepper int open_flags, int create_mode) 1227834f2a4aSTrond Myklebust { 1228834f2a4aSTrond Myklebust struct file *filp = get_empty_filp(); 1229834f2a4aSTrond Myklebust int err; 1230834f2a4aSTrond Myklebust 1231834f2a4aSTrond Myklebust if (filp == NULL) 1232834f2a4aSTrond Myklebust return -ENFILE; 1233834f2a4aSTrond Myklebust nd->intent.open.file = filp; 1234834f2a4aSTrond Myklebust nd->intent.open.flags = open_flags; 1235834f2a4aSTrond Myklebust nd->intent.open.create_mode = create_mode; 12365590ff0dSUlrich Drepper err = do_path_lookup(dfd, name, lookup_flags|LOOKUP_OPEN, nd); 1237834f2a4aSTrond Myklebust if (IS_ERR(nd->intent.open.file)) { 1238834f2a4aSTrond Myklebust if (err == 0) { 1239834f2a4aSTrond Myklebust err = PTR_ERR(nd->intent.open.file); 12401d957f9bSJan Blunck path_put(&nd->path); 1241834f2a4aSTrond Myklebust } 1242834f2a4aSTrond Myklebust } else if (err != 0) 1243834f2a4aSTrond Myklebust release_open_intent(nd); 1244834f2a4aSTrond Myklebust return err; 1245834f2a4aSTrond Myklebust } 1246834f2a4aSTrond Myklebust 1247834f2a4aSTrond Myklebust /** 1248834f2a4aSTrond Myklebust * path_lookup_open - lookup a file path with open intent 12497045f37bSMartin Waitz * @dfd: the directory to use as base, or AT_FDCWD 1250834f2a4aSTrond Myklebust * @name: pointer to file name 1251834f2a4aSTrond Myklebust * @lookup_flags: lookup intent flags 1252834f2a4aSTrond Myklebust * @nd: pointer to nameidata 1253834f2a4aSTrond Myklebust * @open_flags: open intent flags 1254834f2a4aSTrond Myklebust */ 12555590ff0dSUlrich Drepper int path_lookup_open(int dfd, const char *name, unsigned int lookup_flags, 1256834f2a4aSTrond Myklebust struct nameidata *nd, int open_flags) 1257834f2a4aSTrond Myklebust { 12585590ff0dSUlrich Drepper return __path_lookup_intent_open(dfd, name, lookup_flags, nd, 1259834f2a4aSTrond Myklebust open_flags, 0); 1260834f2a4aSTrond Myklebust } 1261834f2a4aSTrond Myklebust 1262834f2a4aSTrond Myklebust /** 1263834f2a4aSTrond Myklebust * path_lookup_create - lookup a file path with open + create intent 12647045f37bSMartin Waitz * @dfd: the directory to use as base, or AT_FDCWD 1265834f2a4aSTrond Myklebust * @name: pointer to file name 1266834f2a4aSTrond Myklebust * @lookup_flags: lookup intent flags 1267834f2a4aSTrond Myklebust * @nd: pointer to nameidata 1268834f2a4aSTrond Myklebust * @open_flags: open intent flags 1269834f2a4aSTrond Myklebust * @create_mode: create intent flags 1270834f2a4aSTrond Myklebust */ 12715590ff0dSUlrich Drepper static int path_lookup_create(int dfd, const char *name, 12725590ff0dSUlrich Drepper unsigned int lookup_flags, struct nameidata *nd, 12735590ff0dSUlrich Drepper int open_flags, int create_mode) 1274834f2a4aSTrond Myklebust { 12755590ff0dSUlrich Drepper return __path_lookup_intent_open(dfd, name, lookup_flags|LOOKUP_CREATE, 12765590ff0dSUlrich Drepper nd, open_flags, create_mode); 1277834f2a4aSTrond Myklebust } 1278834f2a4aSTrond Myklebust 1279834f2a4aSTrond Myklebust int __user_path_lookup_open(const char __user *name, unsigned int lookup_flags, 1280834f2a4aSTrond Myklebust struct nameidata *nd, int open_flags) 1281834f2a4aSTrond Myklebust { 1282834f2a4aSTrond Myklebust char *tmp = getname(name); 1283834f2a4aSTrond Myklebust int err = PTR_ERR(tmp); 1284834f2a4aSTrond Myklebust 1285834f2a4aSTrond Myklebust if (!IS_ERR(tmp)) { 12865590ff0dSUlrich Drepper err = __path_lookup_intent_open(AT_FDCWD, tmp, lookup_flags, nd, open_flags, 0); 1287834f2a4aSTrond Myklebust putname(tmp); 1288834f2a4aSTrond Myklebust } 1289834f2a4aSTrond Myklebust return err; 1290834f2a4aSTrond Myklebust } 1291834f2a4aSTrond Myklebust 1292eead1911SChristoph Hellwig static struct dentry *__lookup_hash(struct qstr *name, 1293eead1911SChristoph Hellwig struct dentry *base, struct nameidata *nd) 12941da177e4SLinus Torvalds { 12951da177e4SLinus Torvalds struct dentry *dentry; 12961da177e4SLinus Torvalds struct inode *inode; 12971da177e4SLinus Torvalds int err; 12981da177e4SLinus Torvalds 12991da177e4SLinus Torvalds inode = base->d_inode; 13001da177e4SLinus Torvalds 13011da177e4SLinus Torvalds /* 13021da177e4SLinus Torvalds * See if the low-level filesystem might want 13031da177e4SLinus Torvalds * to use its own hash.. 13041da177e4SLinus Torvalds */ 13051da177e4SLinus Torvalds if (base->d_op && base->d_op->d_hash) { 13061da177e4SLinus Torvalds err = base->d_op->d_hash(base, name); 13071da177e4SLinus Torvalds dentry = ERR_PTR(err); 13081da177e4SLinus Torvalds if (err < 0) 13091da177e4SLinus Torvalds goto out; 13101da177e4SLinus Torvalds } 13111da177e4SLinus Torvalds 13121da177e4SLinus Torvalds dentry = cached_lookup(base, name, nd); 13131da177e4SLinus Torvalds if (!dentry) { 13141da177e4SLinus Torvalds struct dentry *new = d_alloc(base, name); 13151da177e4SLinus Torvalds dentry = ERR_PTR(-ENOMEM); 13161da177e4SLinus Torvalds if (!new) 13171da177e4SLinus Torvalds goto out; 13181da177e4SLinus Torvalds dentry = inode->i_op->lookup(inode, new, nd); 13191da177e4SLinus Torvalds if (!dentry) 13201da177e4SLinus Torvalds dentry = new; 13211da177e4SLinus Torvalds else 13221da177e4SLinus Torvalds dput(new); 13231da177e4SLinus Torvalds } 13241da177e4SLinus Torvalds out: 13251da177e4SLinus Torvalds return dentry; 13261da177e4SLinus Torvalds } 13271da177e4SLinus Torvalds 1328057f6c01SJames Morris /* 1329057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1330057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1331057f6c01SJames Morris * SMP-safe. 1332057f6c01SJames Morris */ 1333a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 13341da177e4SLinus Torvalds { 1335eead1911SChristoph Hellwig int err; 1336eead1911SChristoph Hellwig 13374ac91378SJan Blunck err = permission(nd->path.dentry->d_inode, MAY_EXEC, nd); 1338eead1911SChristoph Hellwig if (err) 1339eead1911SChristoph Hellwig return ERR_PTR(err); 13404ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 13411da177e4SLinus Torvalds } 13421da177e4SLinus Torvalds 1343eead1911SChristoph Hellwig static int __lookup_one_len(const char *name, struct qstr *this, 1344eead1911SChristoph Hellwig struct dentry *base, int len) 13451da177e4SLinus Torvalds { 13461da177e4SLinus Torvalds unsigned long hash; 13471da177e4SLinus Torvalds unsigned int c; 13481da177e4SLinus Torvalds 1349057f6c01SJames Morris this->name = name; 1350057f6c01SJames Morris this->len = len; 13511da177e4SLinus Torvalds if (!len) 1352057f6c01SJames Morris return -EACCES; 13531da177e4SLinus Torvalds 13541da177e4SLinus Torvalds hash = init_name_hash(); 13551da177e4SLinus Torvalds while (len--) { 13561da177e4SLinus Torvalds c = *(const unsigned char *)name++; 13571da177e4SLinus Torvalds if (c == '/' || c == '\0') 1358057f6c01SJames Morris return -EACCES; 13591da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 13601da177e4SLinus Torvalds } 1361057f6c01SJames Morris this->hash = end_name_hash(hash); 1362057f6c01SJames Morris return 0; 1363057f6c01SJames Morris } 13641da177e4SLinus Torvalds 1365eead1911SChristoph Hellwig /** 1366eead1911SChristoph Hellwig * lookup_one_len: filesystem helper to lookup single pathname component 1367eead1911SChristoph Hellwig * @name: pathname component to lookup 1368eead1911SChristoph Hellwig * @base: base directory to lookup from 1369eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1370eead1911SChristoph Hellwig * 1371eead1911SChristoph Hellwig * Note that this routine is purely a helper for filesystem useage and should 1372eead1911SChristoph Hellwig * not be called by generic code. Also note that by using this function to 1373eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1374eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1375eead1911SChristoph Hellwig */ 1376057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1377057f6c01SJames Morris { 1378057f6c01SJames Morris int err; 1379057f6c01SJames Morris struct qstr this; 1380057f6c01SJames Morris 1381057f6c01SJames Morris err = __lookup_one_len(name, &this, base, len); 1382057f6c01SJames Morris if (err) 1383057f6c01SJames Morris return ERR_PTR(err); 1384eead1911SChristoph Hellwig 1385eead1911SChristoph Hellwig err = permission(base->d_inode, MAY_EXEC, NULL); 1386eead1911SChristoph Hellwig if (err) 1387eead1911SChristoph Hellwig return ERR_PTR(err); 138849705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1389057f6c01SJames Morris } 1390057f6c01SJames Morris 1391eead1911SChristoph Hellwig /** 1392eead1911SChristoph Hellwig * lookup_one_noperm - bad hack for sysfs 1393eead1911SChristoph Hellwig * @name: pathname component to lookup 1394eead1911SChristoph Hellwig * @base: base directory to lookup from 1395eead1911SChristoph Hellwig * 1396eead1911SChristoph Hellwig * This is a variant of lookup_one_len that doesn't perform any permission 1397eead1911SChristoph Hellwig * checks. It's a horrible hack to work around the braindead sysfs 1398eead1911SChristoph Hellwig * architecture and should not be used anywhere else. 1399eead1911SChristoph Hellwig * 1400eead1911SChristoph Hellwig * DON'T USE THIS FUNCTION EVER, thanks. 1401eead1911SChristoph Hellwig */ 1402eead1911SChristoph Hellwig struct dentry *lookup_one_noperm(const char *name, struct dentry *base) 1403057f6c01SJames Morris { 1404057f6c01SJames Morris int err; 1405057f6c01SJames Morris struct qstr this; 1406057f6c01SJames Morris 1407eead1911SChristoph Hellwig err = __lookup_one_len(name, &this, base, strlen(name)); 1408057f6c01SJames Morris if (err) 1409057f6c01SJames Morris return ERR_PTR(err); 1410eead1911SChristoph Hellwig return __lookup_hash(&this, base, NULL); 14111da177e4SLinus Torvalds } 14121da177e4SLinus Torvalds 1413fc9b52cdSHarvey Harrison int __user_walk_fd(int dfd, const char __user *name, unsigned flags, 14145590ff0dSUlrich Drepper struct nameidata *nd) 14151da177e4SLinus Torvalds { 14161da177e4SLinus Torvalds char *tmp = getname(name); 14171da177e4SLinus Torvalds int err = PTR_ERR(tmp); 14181da177e4SLinus Torvalds 14191da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 14205590ff0dSUlrich Drepper err = do_path_lookup(dfd, tmp, flags, nd); 14211da177e4SLinus Torvalds putname(tmp); 14221da177e4SLinus Torvalds } 14231da177e4SLinus Torvalds return err; 14241da177e4SLinus Torvalds } 14251da177e4SLinus Torvalds 1426fc9b52cdSHarvey Harrison int __user_walk(const char __user *name, unsigned flags, struct nameidata *nd) 14275590ff0dSUlrich Drepper { 14285590ff0dSUlrich Drepper return __user_walk_fd(AT_FDCWD, name, flags, nd); 14295590ff0dSUlrich Drepper } 14305590ff0dSUlrich Drepper 14311da177e4SLinus Torvalds /* 14321da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 14331da177e4SLinus Torvalds * minimal. 14341da177e4SLinus Torvalds */ 14351da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 14361da177e4SLinus Torvalds { 14371da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 14381da177e4SLinus Torvalds return 0; 14391da177e4SLinus Torvalds if (inode->i_uid == current->fsuid) 14401da177e4SLinus Torvalds return 0; 14411da177e4SLinus Torvalds if (dir->i_uid == current->fsuid) 14421da177e4SLinus Torvalds return 0; 14431da177e4SLinus Torvalds return !capable(CAP_FOWNER); 14441da177e4SLinus Torvalds } 14451da177e4SLinus Torvalds 14461da177e4SLinus Torvalds /* 14471da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 14481da177e4SLinus Torvalds * whether the type of victim is right. 14491da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 14501da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 14511da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 14521da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 14531da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 14541da177e4SLinus Torvalds * a. be owner of dir, or 14551da177e4SLinus Torvalds * b. be owner of victim, or 14561da177e4SLinus Torvalds * c. have CAP_FOWNER capability 14571da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 14581da177e4SLinus Torvalds * links pointing to it. 14591da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 14601da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 14611da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 14621da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 14631da177e4SLinus Torvalds * nfs_async_unlink(). 14641da177e4SLinus Torvalds */ 1465858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 14661da177e4SLinus Torvalds { 14671da177e4SLinus Torvalds int error; 14681da177e4SLinus Torvalds 14691da177e4SLinus Torvalds if (!victim->d_inode) 14701da177e4SLinus Torvalds return -ENOENT; 14711da177e4SLinus Torvalds 14721da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 14735a190ae6SAl Viro audit_inode_child(victim->d_name.name, victim, dir); 14741da177e4SLinus Torvalds 14751da177e4SLinus Torvalds error = permission(dir,MAY_WRITE | MAY_EXEC, NULL); 14761da177e4SLinus Torvalds if (error) 14771da177e4SLinus Torvalds return error; 14781da177e4SLinus Torvalds if (IS_APPEND(dir)) 14791da177e4SLinus Torvalds return -EPERM; 14801da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 14811da177e4SLinus Torvalds IS_IMMUTABLE(victim->d_inode)) 14821da177e4SLinus Torvalds return -EPERM; 14831da177e4SLinus Torvalds if (isdir) { 14841da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 14851da177e4SLinus Torvalds return -ENOTDIR; 14861da177e4SLinus Torvalds if (IS_ROOT(victim)) 14871da177e4SLinus Torvalds return -EBUSY; 14881da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 14891da177e4SLinus Torvalds return -EISDIR; 14901da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 14911da177e4SLinus Torvalds return -ENOENT; 14921da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 14931da177e4SLinus Torvalds return -EBUSY; 14941da177e4SLinus Torvalds return 0; 14951da177e4SLinus Torvalds } 14961da177e4SLinus Torvalds 14971da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 14981da177e4SLinus Torvalds * dir. 14991da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 15001da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 15011da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 15021da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 15031da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 15041da177e4SLinus Torvalds */ 15051da177e4SLinus Torvalds static inline int may_create(struct inode *dir, struct dentry *child, 15061da177e4SLinus Torvalds struct nameidata *nd) 15071da177e4SLinus Torvalds { 15081da177e4SLinus Torvalds if (child->d_inode) 15091da177e4SLinus Torvalds return -EEXIST; 15101da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 15111da177e4SLinus Torvalds return -ENOENT; 15121da177e4SLinus Torvalds return permission(dir,MAY_WRITE | MAY_EXEC, nd); 15131da177e4SLinus Torvalds } 15141da177e4SLinus Torvalds 15151da177e4SLinus Torvalds /* 15161da177e4SLinus Torvalds * O_DIRECTORY translates into forcing a directory lookup. 15171da177e4SLinus Torvalds */ 15181da177e4SLinus Torvalds static inline int lookup_flags(unsigned int f) 15191da177e4SLinus Torvalds { 15201da177e4SLinus Torvalds unsigned long retval = LOOKUP_FOLLOW; 15211da177e4SLinus Torvalds 15221da177e4SLinus Torvalds if (f & O_NOFOLLOW) 15231da177e4SLinus Torvalds retval &= ~LOOKUP_FOLLOW; 15241da177e4SLinus Torvalds 15251da177e4SLinus Torvalds if (f & O_DIRECTORY) 15261da177e4SLinus Torvalds retval |= LOOKUP_DIRECTORY; 15271da177e4SLinus Torvalds 15281da177e4SLinus Torvalds return retval; 15291da177e4SLinus Torvalds } 15301da177e4SLinus Torvalds 15311da177e4SLinus Torvalds /* 15321da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 15331da177e4SLinus Torvalds */ 15341da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 15351da177e4SLinus Torvalds { 15361da177e4SLinus Torvalds struct dentry *p; 15371da177e4SLinus Torvalds 15381da177e4SLinus Torvalds if (p1 == p2) { 1539f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 15401da177e4SLinus Torvalds return NULL; 15411da177e4SLinus Torvalds } 15421da177e4SLinus Torvalds 1543a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 15441da177e4SLinus Torvalds 15451da177e4SLinus Torvalds for (p = p1; p->d_parent != p; p = p->d_parent) { 15461da177e4SLinus Torvalds if (p->d_parent == p2) { 1547f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 1548f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 15491da177e4SLinus Torvalds return p; 15501da177e4SLinus Torvalds } 15511da177e4SLinus Torvalds } 15521da177e4SLinus Torvalds 15531da177e4SLinus Torvalds for (p = p2; p->d_parent != p; p = p->d_parent) { 15541da177e4SLinus Torvalds if (p->d_parent == p1) { 1555f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1556f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 15571da177e4SLinus Torvalds return p; 15581da177e4SLinus Torvalds } 15591da177e4SLinus Torvalds } 15601da177e4SLinus Torvalds 1561f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1562f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 15631da177e4SLinus Torvalds return NULL; 15641da177e4SLinus Torvalds } 15651da177e4SLinus Torvalds 15661da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 15671da177e4SLinus Torvalds { 15681b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 15691da177e4SLinus Torvalds if (p1 != p2) { 15701b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 1571a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 15721da177e4SLinus Torvalds } 15731da177e4SLinus Torvalds } 15741da177e4SLinus Torvalds 15751da177e4SLinus Torvalds int vfs_create(struct inode *dir, struct dentry *dentry, int mode, 15761da177e4SLinus Torvalds struct nameidata *nd) 15771da177e4SLinus Torvalds { 15781da177e4SLinus Torvalds int error = may_create(dir, dentry, nd); 15791da177e4SLinus Torvalds 15801da177e4SLinus Torvalds if (error) 15811da177e4SLinus Torvalds return error; 15821da177e4SLinus Torvalds 15831da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->create) 15841da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 15851da177e4SLinus Torvalds mode &= S_IALLUGO; 15861da177e4SLinus Torvalds mode |= S_IFREG; 15871da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 15881da177e4SLinus Torvalds if (error) 15891da177e4SLinus Torvalds return error; 15901da177e4SLinus Torvalds DQUOT_INIT(dir); 15911da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 1592a74574aaSStephen Smalley if (!error) 1593f38aa942SAmy Griffis fsnotify_create(dir, dentry); 15941da177e4SLinus Torvalds return error; 15951da177e4SLinus Torvalds } 15961da177e4SLinus Torvalds 15971da177e4SLinus Torvalds int may_open(struct nameidata *nd, int acc_mode, int flag) 15981da177e4SLinus Torvalds { 15994ac91378SJan Blunck struct dentry *dentry = nd->path.dentry; 16001da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 16011da177e4SLinus Torvalds int error; 16021da177e4SLinus Torvalds 16031da177e4SLinus Torvalds if (!inode) 16041da177e4SLinus Torvalds return -ENOENT; 16051da177e4SLinus Torvalds 16061da177e4SLinus Torvalds if (S_ISLNK(inode->i_mode)) 16071da177e4SLinus Torvalds return -ELOOP; 16081da177e4SLinus Torvalds 1609974a9f0bSLinus Torvalds if (S_ISDIR(inode->i_mode) && (acc_mode & MAY_WRITE)) 16101da177e4SLinus Torvalds return -EISDIR; 16111da177e4SLinus Torvalds 16121da177e4SLinus Torvalds /* 16131da177e4SLinus Torvalds * FIFO's, sockets and device files are special: they don't 16141da177e4SLinus Torvalds * actually live on the filesystem itself, and as such you 16151da177e4SLinus Torvalds * can write to them even if the filesystem is read-only. 16161da177e4SLinus Torvalds */ 16171da177e4SLinus Torvalds if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) { 16181da177e4SLinus Torvalds flag &= ~O_TRUNC; 16191da177e4SLinus Torvalds } else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) { 16204ac91378SJan Blunck if (nd->path.mnt->mnt_flags & MNT_NODEV) 16211da177e4SLinus Torvalds return -EACCES; 16221da177e4SLinus Torvalds 16231da177e4SLinus Torvalds flag &= ~O_TRUNC; 1624974a9f0bSLinus Torvalds } else if (IS_RDONLY(inode) && (acc_mode & MAY_WRITE)) 16251da177e4SLinus Torvalds return -EROFS; 1626b41572e9SDave Hansen 1627b41572e9SDave Hansen error = vfs_permission(nd, acc_mode); 1628b41572e9SDave Hansen if (error) 1629b41572e9SDave Hansen return error; 16301da177e4SLinus Torvalds /* 16311da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 16321da177e4SLinus Torvalds */ 16331da177e4SLinus Torvalds if (IS_APPEND(inode)) { 16341da177e4SLinus Torvalds if ((flag & FMODE_WRITE) && !(flag & O_APPEND)) 16351da177e4SLinus Torvalds return -EPERM; 16361da177e4SLinus Torvalds if (flag & O_TRUNC) 16371da177e4SLinus Torvalds return -EPERM; 16381da177e4SLinus Torvalds } 16391da177e4SLinus Torvalds 16401da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 16411da177e4SLinus Torvalds if (flag & O_NOATIME) 16423bd858abSSatyam Sharma if (!is_owner_or_cap(inode)) 16431da177e4SLinus Torvalds return -EPERM; 16441da177e4SLinus Torvalds 16451da177e4SLinus Torvalds /* 16461da177e4SLinus Torvalds * Ensure there are no outstanding leases on the file. 16471da177e4SLinus Torvalds */ 16481da177e4SLinus Torvalds error = break_lease(inode, flag); 16491da177e4SLinus Torvalds if (error) 16501da177e4SLinus Torvalds return error; 16511da177e4SLinus Torvalds 16521da177e4SLinus Torvalds if (flag & O_TRUNC) { 16531da177e4SLinus Torvalds error = get_write_access(inode); 16541da177e4SLinus Torvalds if (error) 16551da177e4SLinus Torvalds return error; 16561da177e4SLinus Torvalds 16571da177e4SLinus Torvalds /* 16581da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 16591da177e4SLinus Torvalds */ 16601da177e4SLinus Torvalds error = locks_verify_locked(inode); 16611da177e4SLinus Torvalds if (!error) { 16621da177e4SLinus Torvalds DQUOT_INIT(inode); 16631da177e4SLinus Torvalds 1664d139d7ffSMiklos Szeredi error = do_truncate(dentry, 0, 1665d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 1666d139d7ffSMiklos Szeredi NULL); 16671da177e4SLinus Torvalds } 16681da177e4SLinus Torvalds put_write_access(inode); 16691da177e4SLinus Torvalds if (error) 16701da177e4SLinus Torvalds return error; 16711da177e4SLinus Torvalds } else 16721da177e4SLinus Torvalds if (flag & FMODE_WRITE) 16731da177e4SLinus Torvalds DQUOT_INIT(inode); 16741da177e4SLinus Torvalds 16751da177e4SLinus Torvalds return 0; 16761da177e4SLinus Torvalds } 16771da177e4SLinus Torvalds 1678aab520e2SDave Hansen static int open_namei_create(struct nameidata *nd, struct path *path, 1679aab520e2SDave Hansen int flag, int mode) 1680aab520e2SDave Hansen { 1681aab520e2SDave Hansen int error; 16824ac91378SJan Blunck struct dentry *dir = nd->path.dentry; 1683aab520e2SDave Hansen 1684aab520e2SDave Hansen if (!IS_POSIXACL(dir->d_inode)) 1685aab520e2SDave Hansen mode &= ~current->fs->umask; 1686aab520e2SDave Hansen error = vfs_create(dir->d_inode, path->dentry, mode, nd); 1687aab520e2SDave Hansen mutex_unlock(&dir->d_inode->i_mutex); 16884ac91378SJan Blunck dput(nd->path.dentry); 16894ac91378SJan Blunck nd->path.dentry = path->dentry; 1690aab520e2SDave Hansen if (error) 1691aab520e2SDave Hansen return error; 1692aab520e2SDave Hansen /* Don't check for write permission, don't truncate */ 1693aab520e2SDave Hansen return may_open(nd, 0, flag & ~O_TRUNC); 1694aab520e2SDave Hansen } 1695aab520e2SDave Hansen 16961da177e4SLinus Torvalds /* 16971da177e4SLinus Torvalds * open_namei() 16981da177e4SLinus Torvalds * 16991da177e4SLinus Torvalds * namei for open - this is in fact almost the whole open-routine. 17001da177e4SLinus Torvalds * 17011da177e4SLinus Torvalds * Note that the low bits of "flag" aren't the same as in the open 17021da177e4SLinus Torvalds * system call - they are 00 - no permissions needed 17031da177e4SLinus Torvalds * 01 - read permission needed 17041da177e4SLinus Torvalds * 10 - write permission needed 17051da177e4SLinus Torvalds * 11 - read/write permissions needed 17061da177e4SLinus Torvalds * which is a lot more logical, and also allows the "no perm" needed 17071da177e4SLinus Torvalds * for symlinks (where the permissions are checked later). 17081da177e4SLinus Torvalds * SMP-safe 17091da177e4SLinus Torvalds */ 17105590ff0dSUlrich Drepper int open_namei(int dfd, const char *pathname, int flag, 17115590ff0dSUlrich Drepper int mode, struct nameidata *nd) 17121da177e4SLinus Torvalds { 1713834f2a4aSTrond Myklebust int acc_mode, error; 17144e7506e4SAl Viro struct path path; 17151da177e4SLinus Torvalds struct dentry *dir; 17161da177e4SLinus Torvalds int count = 0; 17171da177e4SLinus Torvalds 17181da177e4SLinus Torvalds acc_mode = ACC_MODE(flag); 17191da177e4SLinus Torvalds 1720834f2a4aSTrond Myklebust /* O_TRUNC implies we need access checks for write permissions */ 1721834f2a4aSTrond Myklebust if (flag & O_TRUNC) 1722834f2a4aSTrond Myklebust acc_mode |= MAY_WRITE; 1723834f2a4aSTrond Myklebust 17241da177e4SLinus Torvalds /* Allow the LSM permission hook to distinguish append 17251da177e4SLinus Torvalds access from general write access. */ 17261da177e4SLinus Torvalds if (flag & O_APPEND) 17271da177e4SLinus Torvalds acc_mode |= MAY_APPEND; 17281da177e4SLinus Torvalds 17291da177e4SLinus Torvalds /* 17301da177e4SLinus Torvalds * The simplest case - just a plain lookup. 17311da177e4SLinus Torvalds */ 17321da177e4SLinus Torvalds if (!(flag & O_CREAT)) { 17335590ff0dSUlrich Drepper error = path_lookup_open(dfd, pathname, lookup_flags(flag), 17345590ff0dSUlrich Drepper nd, flag); 17351da177e4SLinus Torvalds if (error) 17361da177e4SLinus Torvalds return error; 17371da177e4SLinus Torvalds goto ok; 17381da177e4SLinus Torvalds } 17391da177e4SLinus Torvalds 17401da177e4SLinus Torvalds /* 17411da177e4SLinus Torvalds * Create - we need to know the parent. 17421da177e4SLinus Torvalds */ 17435590ff0dSUlrich Drepper error = path_lookup_create(dfd,pathname,LOOKUP_PARENT,nd,flag,mode); 17441da177e4SLinus Torvalds if (error) 17451da177e4SLinus Torvalds return error; 17461da177e4SLinus Torvalds 17471da177e4SLinus Torvalds /* 17481da177e4SLinus Torvalds * We have the parent and last component. First of all, check 17491da177e4SLinus Torvalds * that we are not asked to creat(2) an obvious directory - that 17501da177e4SLinus Torvalds * will not do. 17511da177e4SLinus Torvalds */ 17521da177e4SLinus Torvalds error = -EISDIR; 17531da177e4SLinus Torvalds if (nd->last_type != LAST_NORM || nd->last.name[nd->last.len]) 17541da177e4SLinus Torvalds goto exit; 17551da177e4SLinus Torvalds 17564ac91378SJan Blunck dir = nd->path.dentry; 17571da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 17581b1dcc1bSJes Sorensen mutex_lock(&dir->d_inode->i_mutex); 175949705b77SChristoph Hellwig path.dentry = lookup_hash(nd); 17604ac91378SJan Blunck path.mnt = nd->path.mnt; 17611da177e4SLinus Torvalds 17621da177e4SLinus Torvalds do_last: 17634e7506e4SAl Viro error = PTR_ERR(path.dentry); 17644e7506e4SAl Viro if (IS_ERR(path.dentry)) { 17651b1dcc1bSJes Sorensen mutex_unlock(&dir->d_inode->i_mutex); 17661da177e4SLinus Torvalds goto exit; 17671da177e4SLinus Torvalds } 17681da177e4SLinus Torvalds 17694af4c52fSOleg Drokin if (IS_ERR(nd->intent.open.file)) { 17704af4c52fSOleg Drokin mutex_unlock(&dir->d_inode->i_mutex); 17714af4c52fSOleg Drokin error = PTR_ERR(nd->intent.open.file); 17724af4c52fSOleg Drokin goto exit_dput; 17734af4c52fSOleg Drokin } 17744af4c52fSOleg Drokin 17751da177e4SLinus Torvalds /* Negative dentry, just create the file */ 17764e7506e4SAl Viro if (!path.dentry->d_inode) { 1777aab520e2SDave Hansen error = open_namei_create(nd, &path, flag, mode); 17781da177e4SLinus Torvalds if (error) 17791da177e4SLinus Torvalds goto exit; 1780aab520e2SDave Hansen return 0; 17811da177e4SLinus Torvalds } 17821da177e4SLinus Torvalds 17831da177e4SLinus Torvalds /* 17841da177e4SLinus Torvalds * It already exists. 17851da177e4SLinus Torvalds */ 17861b1dcc1bSJes Sorensen mutex_unlock(&dir->d_inode->i_mutex); 17875a190ae6SAl Viro audit_inode(pathname, path.dentry); 17881da177e4SLinus Torvalds 17891da177e4SLinus Torvalds error = -EEXIST; 17901da177e4SLinus Torvalds if (flag & O_EXCL) 17911da177e4SLinus Torvalds goto exit_dput; 17921da177e4SLinus Torvalds 1793e13b210fSAl Viro if (__follow_mount(&path)) { 17941da177e4SLinus Torvalds error = -ELOOP; 1795ba7a4c1aSAl Viro if (flag & O_NOFOLLOW) 1796ba7a4c1aSAl Viro goto exit_dput; 17971da177e4SLinus Torvalds } 17983e2efce0SAmy Griffis 17991da177e4SLinus Torvalds error = -ENOENT; 18004e7506e4SAl Viro if (!path.dentry->d_inode) 18011da177e4SLinus Torvalds goto exit_dput; 18024e7506e4SAl Viro if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link) 18031da177e4SLinus Torvalds goto do_link; 18041da177e4SLinus Torvalds 180509dd17d3SMiklos Szeredi path_to_nameidata(&path, nd); 18061da177e4SLinus Torvalds error = -EISDIR; 18074e7506e4SAl Viro if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode)) 18081da177e4SLinus Torvalds goto exit; 18091da177e4SLinus Torvalds ok: 18101da177e4SLinus Torvalds error = may_open(nd, acc_mode, flag); 18111da177e4SLinus Torvalds if (error) 18121da177e4SLinus Torvalds goto exit; 18131da177e4SLinus Torvalds return 0; 18141da177e4SLinus Torvalds 18151da177e4SLinus Torvalds exit_dput: 18161d957f9bSJan Blunck path_put_conditional(&path, nd); 18171da177e4SLinus Torvalds exit: 1818834f2a4aSTrond Myklebust if (!IS_ERR(nd->intent.open.file)) 1819834f2a4aSTrond Myklebust release_open_intent(nd); 18201d957f9bSJan Blunck path_put(&nd->path); 18211da177e4SLinus Torvalds return error; 18221da177e4SLinus Torvalds 18231da177e4SLinus Torvalds do_link: 18241da177e4SLinus Torvalds error = -ELOOP; 18251da177e4SLinus Torvalds if (flag & O_NOFOLLOW) 18261da177e4SLinus Torvalds goto exit_dput; 18271da177e4SLinus Torvalds /* 18281da177e4SLinus Torvalds * This is subtle. Instead of calling do_follow_link() we do the 18291da177e4SLinus Torvalds * thing by hands. The reason is that this way we have zero link_count 18301da177e4SLinus Torvalds * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT. 18311da177e4SLinus Torvalds * After that we have the parent and last component, i.e. 18321da177e4SLinus Torvalds * we are in the same situation as after the first path_walk(). 18331da177e4SLinus Torvalds * Well, almost - if the last component is normal we get its copy 18341da177e4SLinus Torvalds * stored in nd->last.name and we will have to putname() it when we 18351da177e4SLinus Torvalds * are done. Procfs-like symlinks just set LAST_BIND. 18361da177e4SLinus Torvalds */ 18371da177e4SLinus Torvalds nd->flags |= LOOKUP_PARENT; 18384e7506e4SAl Viro error = security_inode_follow_link(path.dentry, nd); 18391da177e4SLinus Torvalds if (error) 18401da177e4SLinus Torvalds goto exit_dput; 1841cd4e91d3SAl Viro error = __do_follow_link(&path, nd); 1842de459215SKirill Korotaev if (error) { 1843de459215SKirill Korotaev /* Does someone understand code flow here? Or it is only 1844de459215SKirill Korotaev * me so stupid? Anathema to whoever designed this non-sense 1845de459215SKirill Korotaev * with "intent.open". 1846de459215SKirill Korotaev */ 1847de459215SKirill Korotaev release_open_intent(nd); 18481da177e4SLinus Torvalds return error; 1849de459215SKirill Korotaev } 18501da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 1851d671d5e5SAl Viro if (nd->last_type == LAST_BIND) 18521da177e4SLinus Torvalds goto ok; 18531da177e4SLinus Torvalds error = -EISDIR; 18541da177e4SLinus Torvalds if (nd->last_type != LAST_NORM) 18551da177e4SLinus Torvalds goto exit; 18561da177e4SLinus Torvalds if (nd->last.name[nd->last.len]) { 185782984114SLinus Torvalds __putname(nd->last.name); 18581da177e4SLinus Torvalds goto exit; 18591da177e4SLinus Torvalds } 18601da177e4SLinus Torvalds error = -ELOOP; 18611da177e4SLinus Torvalds if (count++==32) { 186282984114SLinus Torvalds __putname(nd->last.name); 18631da177e4SLinus Torvalds goto exit; 18641da177e4SLinus Torvalds } 18654ac91378SJan Blunck dir = nd->path.dentry; 18661b1dcc1bSJes Sorensen mutex_lock(&dir->d_inode->i_mutex); 186749705b77SChristoph Hellwig path.dentry = lookup_hash(nd); 18684ac91378SJan Blunck path.mnt = nd->path.mnt; 186982984114SLinus Torvalds __putname(nd->last.name); 18701da177e4SLinus Torvalds goto do_last; 18711da177e4SLinus Torvalds } 18721da177e4SLinus Torvalds 18731da177e4SLinus Torvalds /** 18741da177e4SLinus Torvalds * lookup_create - lookup a dentry, creating it if it doesn't exist 18751da177e4SLinus Torvalds * @nd: nameidata info 18761da177e4SLinus Torvalds * @is_dir: directory flag 18771da177e4SLinus Torvalds * 18781da177e4SLinus Torvalds * Simple function to lookup and return a dentry and create it 18791da177e4SLinus Torvalds * if it doesn't exist. Is SMP-safe. 1880c663e5d8SChristoph Hellwig * 18814ac91378SJan Blunck * Returns with nd->path.dentry->d_inode->i_mutex locked. 18821da177e4SLinus Torvalds */ 18831da177e4SLinus Torvalds struct dentry *lookup_create(struct nameidata *nd, int is_dir) 18841da177e4SLinus Torvalds { 1885c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 18861da177e4SLinus Torvalds 18874ac91378SJan Blunck mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 1888c663e5d8SChristoph Hellwig /* 1889c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 1890c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 1891c663e5d8SChristoph Hellwig */ 18921da177e4SLinus Torvalds if (nd->last_type != LAST_NORM) 18931da177e4SLinus Torvalds goto fail; 18941da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 1895a634904aSASANO Masahiro nd->flags |= LOOKUP_CREATE; 1896a634904aSASANO Masahiro nd->intent.open.flags = O_EXCL; 1897c663e5d8SChristoph Hellwig 1898c663e5d8SChristoph Hellwig /* 1899c663e5d8SChristoph Hellwig * Do the final lookup. 1900c663e5d8SChristoph Hellwig */ 190149705b77SChristoph Hellwig dentry = lookup_hash(nd); 19021da177e4SLinus Torvalds if (IS_ERR(dentry)) 19031da177e4SLinus Torvalds goto fail; 1904c663e5d8SChristoph Hellwig 1905c663e5d8SChristoph Hellwig /* 1906c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 1907c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 1908c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 1909c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 1910c663e5d8SChristoph Hellwig */ 19111da177e4SLinus Torvalds if (!is_dir && nd->last.name[nd->last.len] && !dentry->d_inode) 19121da177e4SLinus Torvalds goto enoent; 19131da177e4SLinus Torvalds return dentry; 19141da177e4SLinus Torvalds enoent: 19151da177e4SLinus Torvalds dput(dentry); 19161da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 19171da177e4SLinus Torvalds fail: 19181da177e4SLinus Torvalds return dentry; 19191da177e4SLinus Torvalds } 1920f81a0bffSChristoph Hellwig EXPORT_SYMBOL_GPL(lookup_create); 19211da177e4SLinus Torvalds 19221da177e4SLinus Torvalds int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 19231da177e4SLinus Torvalds { 19241da177e4SLinus Torvalds int error = may_create(dir, dentry, NULL); 19251da177e4SLinus Torvalds 19261da177e4SLinus Torvalds if (error) 19271da177e4SLinus Torvalds return error; 19281da177e4SLinus Torvalds 19291da177e4SLinus Torvalds if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 19301da177e4SLinus Torvalds return -EPERM; 19311da177e4SLinus Torvalds 19321da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->mknod) 19331da177e4SLinus Torvalds return -EPERM; 19341da177e4SLinus Torvalds 19351da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 19361da177e4SLinus Torvalds if (error) 19371da177e4SLinus Torvalds return error; 19381da177e4SLinus Torvalds 19391da177e4SLinus Torvalds DQUOT_INIT(dir); 19401da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 1941a74574aaSStephen Smalley if (!error) 1942f38aa942SAmy Griffis fsnotify_create(dir, dentry); 19431da177e4SLinus Torvalds return error; 19441da177e4SLinus Torvalds } 19451da177e4SLinus Torvalds 19465590ff0dSUlrich Drepper asmlinkage long sys_mknodat(int dfd, const char __user *filename, int mode, 19475590ff0dSUlrich Drepper unsigned dev) 19481da177e4SLinus Torvalds { 19491da177e4SLinus Torvalds int error = 0; 19501da177e4SLinus Torvalds char * tmp; 19511da177e4SLinus Torvalds struct dentry * dentry; 19521da177e4SLinus Torvalds struct nameidata nd; 19531da177e4SLinus Torvalds 19541da177e4SLinus Torvalds if (S_ISDIR(mode)) 19551da177e4SLinus Torvalds return -EPERM; 19561da177e4SLinus Torvalds tmp = getname(filename); 19571da177e4SLinus Torvalds if (IS_ERR(tmp)) 19581da177e4SLinus Torvalds return PTR_ERR(tmp); 19591da177e4SLinus Torvalds 19605590ff0dSUlrich Drepper error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd); 19611da177e4SLinus Torvalds if (error) 19621da177e4SLinus Torvalds goto out; 19631da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 19641da177e4SLinus Torvalds error = PTR_ERR(dentry); 19651da177e4SLinus Torvalds 19664ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 19671da177e4SLinus Torvalds mode &= ~current->fs->umask; 19681da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 19691da177e4SLinus Torvalds switch (mode & S_IFMT) { 19701da177e4SLinus Torvalds case 0: case S_IFREG: 19714ac91378SJan Blunck error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); 19721da177e4SLinus Torvalds break; 19731da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 19744ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, 19751da177e4SLinus Torvalds new_decode_dev(dev)); 19761da177e4SLinus Torvalds break; 19771da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 19784ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); 19791da177e4SLinus Torvalds break; 19801da177e4SLinus Torvalds case S_IFDIR: 19811da177e4SLinus Torvalds error = -EPERM; 19821da177e4SLinus Torvalds break; 19831da177e4SLinus Torvalds default: 19841da177e4SLinus Torvalds error = -EINVAL; 19851da177e4SLinus Torvalds } 19861da177e4SLinus Torvalds dput(dentry); 19871da177e4SLinus Torvalds } 19884ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 19891d957f9bSJan Blunck path_put(&nd.path); 19901da177e4SLinus Torvalds out: 19911da177e4SLinus Torvalds putname(tmp); 19921da177e4SLinus Torvalds 19931da177e4SLinus Torvalds return error; 19941da177e4SLinus Torvalds } 19951da177e4SLinus Torvalds 19965590ff0dSUlrich Drepper asmlinkage long sys_mknod(const char __user *filename, int mode, unsigned dev) 19975590ff0dSUlrich Drepper { 19985590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 19995590ff0dSUlrich Drepper } 20005590ff0dSUlrich Drepper 20011da177e4SLinus Torvalds int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 20021da177e4SLinus Torvalds { 20031da177e4SLinus Torvalds int error = may_create(dir, dentry, NULL); 20041da177e4SLinus Torvalds 20051da177e4SLinus Torvalds if (error) 20061da177e4SLinus Torvalds return error; 20071da177e4SLinus Torvalds 20081da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->mkdir) 20091da177e4SLinus Torvalds return -EPERM; 20101da177e4SLinus Torvalds 20111da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 20121da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 20131da177e4SLinus Torvalds if (error) 20141da177e4SLinus Torvalds return error; 20151da177e4SLinus Torvalds 20161da177e4SLinus Torvalds DQUOT_INIT(dir); 20171da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2018a74574aaSStephen Smalley if (!error) 2019f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 20201da177e4SLinus Torvalds return error; 20211da177e4SLinus Torvalds } 20221da177e4SLinus Torvalds 20235590ff0dSUlrich Drepper asmlinkage long sys_mkdirat(int dfd, const char __user *pathname, int mode) 20241da177e4SLinus Torvalds { 20251da177e4SLinus Torvalds int error = 0; 20261da177e4SLinus Torvalds char * tmp; 20276902d925SDave Hansen struct dentry *dentry; 20286902d925SDave Hansen struct nameidata nd; 20291da177e4SLinus Torvalds 20301da177e4SLinus Torvalds tmp = getname(pathname); 20311da177e4SLinus Torvalds error = PTR_ERR(tmp); 20326902d925SDave Hansen if (IS_ERR(tmp)) 20336902d925SDave Hansen goto out_err; 20341da177e4SLinus Torvalds 20355590ff0dSUlrich Drepper error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd); 20361da177e4SLinus Torvalds if (error) 20371da177e4SLinus Torvalds goto out; 20381da177e4SLinus Torvalds dentry = lookup_create(&nd, 1); 20391da177e4SLinus Torvalds error = PTR_ERR(dentry); 20406902d925SDave Hansen if (IS_ERR(dentry)) 20416902d925SDave Hansen goto out_unlock; 20426902d925SDave Hansen 20434ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 20441da177e4SLinus Torvalds mode &= ~current->fs->umask; 20454ac91378SJan Blunck error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); 20461da177e4SLinus Torvalds dput(dentry); 20476902d925SDave Hansen out_unlock: 20484ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 20491d957f9bSJan Blunck path_put(&nd.path); 20501da177e4SLinus Torvalds out: 20511da177e4SLinus Torvalds putname(tmp); 20526902d925SDave Hansen out_err: 20531da177e4SLinus Torvalds return error; 20541da177e4SLinus Torvalds } 20551da177e4SLinus Torvalds 20565590ff0dSUlrich Drepper asmlinkage long sys_mkdir(const char __user *pathname, int mode) 20575590ff0dSUlrich Drepper { 20585590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 20595590ff0dSUlrich Drepper } 20605590ff0dSUlrich Drepper 20611da177e4SLinus Torvalds /* 20621da177e4SLinus Torvalds * We try to drop the dentry early: we should have 20631da177e4SLinus Torvalds * a usage count of 2 if we're the only user of this 20641da177e4SLinus Torvalds * dentry, and if that is true (possibly after pruning 20651da177e4SLinus Torvalds * the dcache), then we drop the dentry now. 20661da177e4SLinus Torvalds * 20671da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 20681da177e4SLinus Torvalds * do a 20691da177e4SLinus Torvalds * 20701da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 20711da177e4SLinus Torvalds * return -EBUSY; 20721da177e4SLinus Torvalds * 20731da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 20741da177e4SLinus Torvalds * that is still in use by something else.. 20751da177e4SLinus Torvalds */ 20761da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 20771da177e4SLinus Torvalds { 20781da177e4SLinus Torvalds dget(dentry); 20791da177e4SLinus Torvalds shrink_dcache_parent(dentry); 20801da177e4SLinus Torvalds spin_lock(&dcache_lock); 20811da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 20821da177e4SLinus Torvalds if (atomic_read(&dentry->d_count) == 2) 20831da177e4SLinus Torvalds __d_drop(dentry); 20841da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 20851da177e4SLinus Torvalds spin_unlock(&dcache_lock); 20861da177e4SLinus Torvalds } 20871da177e4SLinus Torvalds 20881da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 20891da177e4SLinus Torvalds { 20901da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 20911da177e4SLinus Torvalds 20921da177e4SLinus Torvalds if (error) 20931da177e4SLinus Torvalds return error; 20941da177e4SLinus Torvalds 20951da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->rmdir) 20961da177e4SLinus Torvalds return -EPERM; 20971da177e4SLinus Torvalds 20981da177e4SLinus Torvalds DQUOT_INIT(dir); 20991da177e4SLinus Torvalds 21001b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 21011da177e4SLinus Torvalds dentry_unhash(dentry); 21021da177e4SLinus Torvalds if (d_mountpoint(dentry)) 21031da177e4SLinus Torvalds error = -EBUSY; 21041da177e4SLinus Torvalds else { 21051da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 21061da177e4SLinus Torvalds if (!error) { 21071da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 21081da177e4SLinus Torvalds if (!error) 21091da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 21101da177e4SLinus Torvalds } 21111da177e4SLinus Torvalds } 21121b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 21131da177e4SLinus Torvalds if (!error) { 21141da177e4SLinus Torvalds d_delete(dentry); 21151da177e4SLinus Torvalds } 21161da177e4SLinus Torvalds dput(dentry); 21171da177e4SLinus Torvalds 21181da177e4SLinus Torvalds return error; 21191da177e4SLinus Torvalds } 21201da177e4SLinus Torvalds 21215590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 21221da177e4SLinus Torvalds { 21231da177e4SLinus Torvalds int error = 0; 21241da177e4SLinus Torvalds char * name; 21251da177e4SLinus Torvalds struct dentry *dentry; 21261da177e4SLinus Torvalds struct nameidata nd; 21271da177e4SLinus Torvalds 21281da177e4SLinus Torvalds name = getname(pathname); 21291da177e4SLinus Torvalds if(IS_ERR(name)) 21301da177e4SLinus Torvalds return PTR_ERR(name); 21311da177e4SLinus Torvalds 21325590ff0dSUlrich Drepper error = do_path_lookup(dfd, name, LOOKUP_PARENT, &nd); 21331da177e4SLinus Torvalds if (error) 21341da177e4SLinus Torvalds goto exit; 21351da177e4SLinus Torvalds 21361da177e4SLinus Torvalds switch(nd.last_type) { 21371da177e4SLinus Torvalds case LAST_DOTDOT: 21381da177e4SLinus Torvalds error = -ENOTEMPTY; 21391da177e4SLinus Torvalds goto exit1; 21401da177e4SLinus Torvalds case LAST_DOT: 21411da177e4SLinus Torvalds error = -EINVAL; 21421da177e4SLinus Torvalds goto exit1; 21431da177e4SLinus Torvalds case LAST_ROOT: 21441da177e4SLinus Torvalds error = -EBUSY; 21451da177e4SLinus Torvalds goto exit1; 21461da177e4SLinus Torvalds } 21474ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 214849705b77SChristoph Hellwig dentry = lookup_hash(&nd); 21491da177e4SLinus Torvalds error = PTR_ERR(dentry); 21506902d925SDave Hansen if (IS_ERR(dentry)) 21516902d925SDave Hansen goto exit2; 21524ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 21531da177e4SLinus Torvalds dput(dentry); 21546902d925SDave Hansen exit2: 21554ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 21561da177e4SLinus Torvalds exit1: 21571d957f9bSJan Blunck path_put(&nd.path); 21581da177e4SLinus Torvalds exit: 21591da177e4SLinus Torvalds putname(name); 21601da177e4SLinus Torvalds return error; 21611da177e4SLinus Torvalds } 21621da177e4SLinus Torvalds 21635590ff0dSUlrich Drepper asmlinkage long sys_rmdir(const char __user *pathname) 21645590ff0dSUlrich Drepper { 21655590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 21665590ff0dSUlrich Drepper } 21675590ff0dSUlrich Drepper 21681da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 21691da177e4SLinus Torvalds { 21701da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 21711da177e4SLinus Torvalds 21721da177e4SLinus Torvalds if (error) 21731da177e4SLinus Torvalds return error; 21741da177e4SLinus Torvalds 21751da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->unlink) 21761da177e4SLinus Torvalds return -EPERM; 21771da177e4SLinus Torvalds 21781da177e4SLinus Torvalds DQUOT_INIT(dir); 21791da177e4SLinus Torvalds 21801b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 21811da177e4SLinus Torvalds if (d_mountpoint(dentry)) 21821da177e4SLinus Torvalds error = -EBUSY; 21831da177e4SLinus Torvalds else { 21841da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 21851da177e4SLinus Torvalds if (!error) 21861da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 21871da177e4SLinus Torvalds } 21881b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 21891da177e4SLinus Torvalds 21901da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 21911da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2192ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 21931da177e4SLinus Torvalds d_delete(dentry); 21941da177e4SLinus Torvalds } 21950eeca283SRobert Love 21961da177e4SLinus Torvalds return error; 21971da177e4SLinus Torvalds } 21981da177e4SLinus Torvalds 21991da177e4SLinus Torvalds /* 22001da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 22011b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 22021da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 22031da177e4SLinus Torvalds * while waiting on the I/O. 22041da177e4SLinus Torvalds */ 22055590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 22061da177e4SLinus Torvalds { 22071da177e4SLinus Torvalds int error = 0; 22081da177e4SLinus Torvalds char * name; 22091da177e4SLinus Torvalds struct dentry *dentry; 22101da177e4SLinus Torvalds struct nameidata nd; 22111da177e4SLinus Torvalds struct inode *inode = NULL; 22121da177e4SLinus Torvalds 22131da177e4SLinus Torvalds name = getname(pathname); 22141da177e4SLinus Torvalds if(IS_ERR(name)) 22151da177e4SLinus Torvalds return PTR_ERR(name); 22161da177e4SLinus Torvalds 22175590ff0dSUlrich Drepper error = do_path_lookup(dfd, name, LOOKUP_PARENT, &nd); 22181da177e4SLinus Torvalds if (error) 22191da177e4SLinus Torvalds goto exit; 22201da177e4SLinus Torvalds error = -EISDIR; 22211da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 22221da177e4SLinus Torvalds goto exit1; 22234ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 222449705b77SChristoph Hellwig dentry = lookup_hash(&nd); 22251da177e4SLinus Torvalds error = PTR_ERR(dentry); 22261da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 22271da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 22281da177e4SLinus Torvalds if (nd.last.name[nd.last.len]) 22291da177e4SLinus Torvalds goto slashes; 22301da177e4SLinus Torvalds inode = dentry->d_inode; 22311da177e4SLinus Torvalds if (inode) 22321da177e4SLinus Torvalds atomic_inc(&inode->i_count); 22334ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 22341da177e4SLinus Torvalds exit2: 22351da177e4SLinus Torvalds dput(dentry); 22361da177e4SLinus Torvalds } 22374ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 22381da177e4SLinus Torvalds if (inode) 22391da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 22401da177e4SLinus Torvalds exit1: 22411d957f9bSJan Blunck path_put(&nd.path); 22421da177e4SLinus Torvalds exit: 22431da177e4SLinus Torvalds putname(name); 22441da177e4SLinus Torvalds return error; 22451da177e4SLinus Torvalds 22461da177e4SLinus Torvalds slashes: 22471da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 22481da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 22491da177e4SLinus Torvalds goto exit2; 22501da177e4SLinus Torvalds } 22511da177e4SLinus Torvalds 22525590ff0dSUlrich Drepper asmlinkage long sys_unlinkat(int dfd, const char __user *pathname, int flag) 22535590ff0dSUlrich Drepper { 22545590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 22555590ff0dSUlrich Drepper return -EINVAL; 22565590ff0dSUlrich Drepper 22575590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 22585590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 22595590ff0dSUlrich Drepper 22605590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 22615590ff0dSUlrich Drepper } 22625590ff0dSUlrich Drepper 22635590ff0dSUlrich Drepper asmlinkage long sys_unlink(const char __user *pathname) 22645590ff0dSUlrich Drepper { 22655590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 22665590ff0dSUlrich Drepper } 22675590ff0dSUlrich Drepper 22681da177e4SLinus Torvalds int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname, int mode) 22691da177e4SLinus Torvalds { 22701da177e4SLinus Torvalds int error = may_create(dir, dentry, NULL); 22711da177e4SLinus Torvalds 22721da177e4SLinus Torvalds if (error) 22731da177e4SLinus Torvalds return error; 22741da177e4SLinus Torvalds 22751da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->symlink) 22761da177e4SLinus Torvalds return -EPERM; 22771da177e4SLinus Torvalds 22781da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 22791da177e4SLinus Torvalds if (error) 22801da177e4SLinus Torvalds return error; 22811da177e4SLinus Torvalds 22821da177e4SLinus Torvalds DQUOT_INIT(dir); 22831da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2284a74574aaSStephen Smalley if (!error) 2285f38aa942SAmy Griffis fsnotify_create(dir, dentry); 22861da177e4SLinus Torvalds return error; 22871da177e4SLinus Torvalds } 22881da177e4SLinus Torvalds 22895590ff0dSUlrich Drepper asmlinkage long sys_symlinkat(const char __user *oldname, 22905590ff0dSUlrich Drepper int newdfd, const char __user *newname) 22911da177e4SLinus Torvalds { 22921da177e4SLinus Torvalds int error = 0; 22931da177e4SLinus Torvalds char * from; 22941da177e4SLinus Torvalds char * to; 22956902d925SDave Hansen struct dentry *dentry; 22966902d925SDave Hansen struct nameidata nd; 22971da177e4SLinus Torvalds 22981da177e4SLinus Torvalds from = getname(oldname); 22991da177e4SLinus Torvalds if(IS_ERR(from)) 23001da177e4SLinus Torvalds return PTR_ERR(from); 23011da177e4SLinus Torvalds to = getname(newname); 23021da177e4SLinus Torvalds error = PTR_ERR(to); 23036902d925SDave Hansen if (IS_ERR(to)) 23046902d925SDave Hansen goto out_putname; 23051da177e4SLinus Torvalds 23065590ff0dSUlrich Drepper error = do_path_lookup(newdfd, to, LOOKUP_PARENT, &nd); 23071da177e4SLinus Torvalds if (error) 23081da177e4SLinus Torvalds goto out; 23091da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 23101da177e4SLinus Torvalds error = PTR_ERR(dentry); 23116902d925SDave Hansen if (IS_ERR(dentry)) 23126902d925SDave Hansen goto out_unlock; 23136902d925SDave Hansen 23144ac91378SJan Blunck error = vfs_symlink(nd.path.dentry->d_inode, dentry, from, S_IALLUGO); 23151da177e4SLinus Torvalds dput(dentry); 23166902d925SDave Hansen out_unlock: 23174ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 23181d957f9bSJan Blunck path_put(&nd.path); 23191da177e4SLinus Torvalds out: 23201da177e4SLinus Torvalds putname(to); 23216902d925SDave Hansen out_putname: 23221da177e4SLinus Torvalds putname(from); 23231da177e4SLinus Torvalds return error; 23241da177e4SLinus Torvalds } 23251da177e4SLinus Torvalds 23265590ff0dSUlrich Drepper asmlinkage long sys_symlink(const char __user *oldname, const char __user *newname) 23275590ff0dSUlrich Drepper { 23285590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 23295590ff0dSUlrich Drepper } 23305590ff0dSUlrich Drepper 23311da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 23321da177e4SLinus Torvalds { 23331da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 23341da177e4SLinus Torvalds int error; 23351da177e4SLinus Torvalds 23361da177e4SLinus Torvalds if (!inode) 23371da177e4SLinus Torvalds return -ENOENT; 23381da177e4SLinus Torvalds 23391da177e4SLinus Torvalds error = may_create(dir, new_dentry, NULL); 23401da177e4SLinus Torvalds if (error) 23411da177e4SLinus Torvalds return error; 23421da177e4SLinus Torvalds 23431da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 23441da177e4SLinus Torvalds return -EXDEV; 23451da177e4SLinus Torvalds 23461da177e4SLinus Torvalds /* 23471da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 23481da177e4SLinus Torvalds */ 23491da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 23501da177e4SLinus Torvalds return -EPERM; 23511da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->link) 23521da177e4SLinus Torvalds return -EPERM; 23531da177e4SLinus Torvalds if (S_ISDIR(old_dentry->d_inode->i_mode)) 23541da177e4SLinus Torvalds return -EPERM; 23551da177e4SLinus Torvalds 23561da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 23571da177e4SLinus Torvalds if (error) 23581da177e4SLinus Torvalds return error; 23591da177e4SLinus Torvalds 23601b1dcc1bSJes Sorensen mutex_lock(&old_dentry->d_inode->i_mutex); 23611da177e4SLinus Torvalds DQUOT_INIT(dir); 23621da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 23631b1dcc1bSJes Sorensen mutex_unlock(&old_dentry->d_inode->i_mutex); 2364e31e14ecSStephen Smalley if (!error) 2365ece95912SJan Kara fsnotify_link(dir, old_dentry->d_inode, new_dentry); 23661da177e4SLinus Torvalds return error; 23671da177e4SLinus Torvalds } 23681da177e4SLinus Torvalds 23691da177e4SLinus Torvalds /* 23701da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 23711da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 23721da177e4SLinus Torvalds * newname. --KAB 23731da177e4SLinus Torvalds * 23741da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 23751da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 23761da177e4SLinus Torvalds * and other special files. --ADM 23771da177e4SLinus Torvalds */ 23785590ff0dSUlrich Drepper asmlinkage long sys_linkat(int olddfd, const char __user *oldname, 2379c04030e1SUlrich Drepper int newdfd, const char __user *newname, 2380c04030e1SUlrich Drepper int flags) 23811da177e4SLinus Torvalds { 23821da177e4SLinus Torvalds struct dentry *new_dentry; 23831da177e4SLinus Torvalds struct nameidata nd, old_nd; 23841da177e4SLinus Torvalds int error; 23851da177e4SLinus Torvalds char * to; 23861da177e4SLinus Torvalds 238745c9b11aSUlrich Drepper if ((flags & ~AT_SYMLINK_FOLLOW) != 0) 2388c04030e1SUlrich Drepper return -EINVAL; 2389c04030e1SUlrich Drepper 23901da177e4SLinus Torvalds to = getname(newname); 23911da177e4SLinus Torvalds if (IS_ERR(to)) 23921da177e4SLinus Torvalds return PTR_ERR(to); 23931da177e4SLinus Torvalds 239445c9b11aSUlrich Drepper error = __user_walk_fd(olddfd, oldname, 239545c9b11aSUlrich Drepper flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0, 239645c9b11aSUlrich Drepper &old_nd); 23971da177e4SLinus Torvalds if (error) 23981da177e4SLinus Torvalds goto exit; 23995590ff0dSUlrich Drepper error = do_path_lookup(newdfd, to, LOOKUP_PARENT, &nd); 24001da177e4SLinus Torvalds if (error) 24011da177e4SLinus Torvalds goto out; 24021da177e4SLinus Torvalds error = -EXDEV; 24034ac91378SJan Blunck if (old_nd.path.mnt != nd.path.mnt) 24041da177e4SLinus Torvalds goto out_release; 24051da177e4SLinus Torvalds new_dentry = lookup_create(&nd, 0); 24061da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 24076902d925SDave Hansen if (IS_ERR(new_dentry)) 24086902d925SDave Hansen goto out_unlock; 24094ac91378SJan Blunck error = vfs_link(old_nd.path.dentry, nd.path.dentry->d_inode, new_dentry); 24101da177e4SLinus Torvalds dput(new_dentry); 24116902d925SDave Hansen out_unlock: 24124ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 24131da177e4SLinus Torvalds out_release: 24141d957f9bSJan Blunck path_put(&nd.path); 24151da177e4SLinus Torvalds out: 24161d957f9bSJan Blunck path_put(&old_nd.path); 24171da177e4SLinus Torvalds exit: 24181da177e4SLinus Torvalds putname(to); 24191da177e4SLinus Torvalds 24201da177e4SLinus Torvalds return error; 24211da177e4SLinus Torvalds } 24221da177e4SLinus Torvalds 24235590ff0dSUlrich Drepper asmlinkage long sys_link(const char __user *oldname, const char __user *newname) 24245590ff0dSUlrich Drepper { 2425c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 24265590ff0dSUlrich Drepper } 24275590ff0dSUlrich Drepper 24281da177e4SLinus Torvalds /* 24291da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 24301da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 24311da177e4SLinus Torvalds * Problems: 24321da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 24331da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 24341da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 2435a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 24361da177e4SLinus Torvalds * story. 24371da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 24381b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 24391da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 24401da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 2441a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 24421da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 24431da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 24441da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 2445a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 24461da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 24471da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 24481da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 24491da177e4SLinus Torvalds * d) some filesystems don't support opened-but-unlinked directories, 24501da177e4SLinus Torvalds * either because of layout or because they are not ready to deal with 24511da177e4SLinus Torvalds * all cases correctly. The latter will be fixed (taking this sort of 24521da177e4SLinus Torvalds * stuff into VFS), but the former is not going away. Solution: the same 24531da177e4SLinus Torvalds * trick as in rmdir(). 24541da177e4SLinus Torvalds * e) conversion from fhandle to dentry may come in the wrong moment - when 24551b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 24561da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 24571b1dcc1bSJes Sorensen * ->i_mutex on parents, which works but leads to some truely excessive 24581da177e4SLinus Torvalds * locking]. 24591da177e4SLinus Torvalds */ 246075c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 24611da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 24621da177e4SLinus Torvalds { 24631da177e4SLinus Torvalds int error = 0; 24641da177e4SLinus Torvalds struct inode *target; 24651da177e4SLinus Torvalds 24661da177e4SLinus Torvalds /* 24671da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 24681da177e4SLinus Torvalds * we'll need to flip '..'. 24691da177e4SLinus Torvalds */ 24701da177e4SLinus Torvalds if (new_dir != old_dir) { 24711da177e4SLinus Torvalds error = permission(old_dentry->d_inode, MAY_WRITE, NULL); 24721da177e4SLinus Torvalds if (error) 24731da177e4SLinus Torvalds return error; 24741da177e4SLinus Torvalds } 24751da177e4SLinus Torvalds 24761da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 24771da177e4SLinus Torvalds if (error) 24781da177e4SLinus Torvalds return error; 24791da177e4SLinus Torvalds 24801da177e4SLinus Torvalds target = new_dentry->d_inode; 24811da177e4SLinus Torvalds if (target) { 24821b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 24831da177e4SLinus Torvalds dentry_unhash(new_dentry); 24841da177e4SLinus Torvalds } 24851da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 24861da177e4SLinus Torvalds error = -EBUSY; 24871da177e4SLinus Torvalds else 24881da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 24891da177e4SLinus Torvalds if (target) { 24901da177e4SLinus Torvalds if (!error) 24911da177e4SLinus Torvalds target->i_flags |= S_DEAD; 24921b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 24931da177e4SLinus Torvalds if (d_unhashed(new_dentry)) 24941da177e4SLinus Torvalds d_rehash(new_dentry); 24951da177e4SLinus Torvalds dput(new_dentry); 24961da177e4SLinus Torvalds } 2497e31e14ecSStephen Smalley if (!error) 2498349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 24991da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 25001da177e4SLinus Torvalds return error; 25011da177e4SLinus Torvalds } 25021da177e4SLinus Torvalds 250375c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 25041da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 25051da177e4SLinus Torvalds { 25061da177e4SLinus Torvalds struct inode *target; 25071da177e4SLinus Torvalds int error; 25081da177e4SLinus Torvalds 25091da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 25101da177e4SLinus Torvalds if (error) 25111da177e4SLinus Torvalds return error; 25121da177e4SLinus Torvalds 25131da177e4SLinus Torvalds dget(new_dentry); 25141da177e4SLinus Torvalds target = new_dentry->d_inode; 25151da177e4SLinus Torvalds if (target) 25161b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 25171da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 25181da177e4SLinus Torvalds error = -EBUSY; 25191da177e4SLinus Torvalds else 25201da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 25211da177e4SLinus Torvalds if (!error) { 2522349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 25231da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 25241da177e4SLinus Torvalds } 25251da177e4SLinus Torvalds if (target) 25261b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 25271da177e4SLinus Torvalds dput(new_dentry); 25281da177e4SLinus Torvalds return error; 25291da177e4SLinus Torvalds } 25301da177e4SLinus Torvalds 25311da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 25321da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 25331da177e4SLinus Torvalds { 25341da177e4SLinus Torvalds int error; 25351da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 25360eeca283SRobert Love const char *old_name; 25371da177e4SLinus Torvalds 25381da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 25391da177e4SLinus Torvalds return 0; 25401da177e4SLinus Torvalds 25411da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 25421da177e4SLinus Torvalds if (error) 25431da177e4SLinus Torvalds return error; 25441da177e4SLinus Torvalds 25451da177e4SLinus Torvalds if (!new_dentry->d_inode) 25461da177e4SLinus Torvalds error = may_create(new_dir, new_dentry, NULL); 25471da177e4SLinus Torvalds else 25481da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 25491da177e4SLinus Torvalds if (error) 25501da177e4SLinus Torvalds return error; 25511da177e4SLinus Torvalds 25521da177e4SLinus Torvalds if (!old_dir->i_op || !old_dir->i_op->rename) 25531da177e4SLinus Torvalds return -EPERM; 25541da177e4SLinus Torvalds 25551da177e4SLinus Torvalds DQUOT_INIT(old_dir); 25561da177e4SLinus Torvalds DQUOT_INIT(new_dir); 25571da177e4SLinus Torvalds 25580eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 25590eeca283SRobert Love 25601da177e4SLinus Torvalds if (is_dir) 25611da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 25621da177e4SLinus Torvalds else 25631da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 25641da177e4SLinus Torvalds if (!error) { 25650eeca283SRobert Love const char *new_name = old_dentry->d_name.name; 256689204c40SJohn McCutchan fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir, 25675a190ae6SAl Viro new_dentry->d_inode, old_dentry); 25681da177e4SLinus Torvalds } 25690eeca283SRobert Love fsnotify_oldname_free(old_name); 25700eeca283SRobert Love 25711da177e4SLinus Torvalds return error; 25721da177e4SLinus Torvalds } 25731da177e4SLinus Torvalds 25745590ff0dSUlrich Drepper static int do_rename(int olddfd, const char *oldname, 25755590ff0dSUlrich Drepper int newdfd, const char *newname) 25761da177e4SLinus Torvalds { 25771da177e4SLinus Torvalds int error = 0; 25781da177e4SLinus Torvalds struct dentry * old_dir, * new_dir; 25791da177e4SLinus Torvalds struct dentry * old_dentry, *new_dentry; 25801da177e4SLinus Torvalds struct dentry * trap; 25811da177e4SLinus Torvalds struct nameidata oldnd, newnd; 25821da177e4SLinus Torvalds 25835590ff0dSUlrich Drepper error = do_path_lookup(olddfd, oldname, LOOKUP_PARENT, &oldnd); 25841da177e4SLinus Torvalds if (error) 25851da177e4SLinus Torvalds goto exit; 25861da177e4SLinus Torvalds 25875590ff0dSUlrich Drepper error = do_path_lookup(newdfd, newname, LOOKUP_PARENT, &newnd); 25881da177e4SLinus Torvalds if (error) 25891da177e4SLinus Torvalds goto exit1; 25901da177e4SLinus Torvalds 25911da177e4SLinus Torvalds error = -EXDEV; 25924ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 25931da177e4SLinus Torvalds goto exit2; 25941da177e4SLinus Torvalds 25954ac91378SJan Blunck old_dir = oldnd.path.dentry; 25961da177e4SLinus Torvalds error = -EBUSY; 25971da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 25981da177e4SLinus Torvalds goto exit2; 25991da177e4SLinus Torvalds 26004ac91378SJan Blunck new_dir = newnd.path.dentry; 26011da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 26021da177e4SLinus Torvalds goto exit2; 26031da177e4SLinus Torvalds 26041da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 26051da177e4SLinus Torvalds 260649705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 26071da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 26081da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 26091da177e4SLinus Torvalds goto exit3; 26101da177e4SLinus Torvalds /* source must exist */ 26111da177e4SLinus Torvalds error = -ENOENT; 26121da177e4SLinus Torvalds if (!old_dentry->d_inode) 26131da177e4SLinus Torvalds goto exit4; 26141da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 26151da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 26161da177e4SLinus Torvalds error = -ENOTDIR; 26171da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 26181da177e4SLinus Torvalds goto exit4; 26191da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 26201da177e4SLinus Torvalds goto exit4; 26211da177e4SLinus Torvalds } 26221da177e4SLinus Torvalds /* source should not be ancestor of target */ 26231da177e4SLinus Torvalds error = -EINVAL; 26241da177e4SLinus Torvalds if (old_dentry == trap) 26251da177e4SLinus Torvalds goto exit4; 262649705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 26271da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 26281da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 26291da177e4SLinus Torvalds goto exit4; 26301da177e4SLinus Torvalds /* target should not be an ancestor of source */ 26311da177e4SLinus Torvalds error = -ENOTEMPTY; 26321da177e4SLinus Torvalds if (new_dentry == trap) 26331da177e4SLinus Torvalds goto exit5; 26341da177e4SLinus Torvalds 26351da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 26361da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 26371da177e4SLinus Torvalds exit5: 26381da177e4SLinus Torvalds dput(new_dentry); 26391da177e4SLinus Torvalds exit4: 26401da177e4SLinus Torvalds dput(old_dentry); 26411da177e4SLinus Torvalds exit3: 26421da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 26431da177e4SLinus Torvalds exit2: 26441d957f9bSJan Blunck path_put(&newnd.path); 26451da177e4SLinus Torvalds exit1: 26461d957f9bSJan Blunck path_put(&oldnd.path); 26471da177e4SLinus Torvalds exit: 26481da177e4SLinus Torvalds return error; 26491da177e4SLinus Torvalds } 26501da177e4SLinus Torvalds 26515590ff0dSUlrich Drepper asmlinkage long sys_renameat(int olddfd, const char __user *oldname, 26525590ff0dSUlrich Drepper int newdfd, const char __user *newname) 26531da177e4SLinus Torvalds { 26541da177e4SLinus Torvalds int error; 26551da177e4SLinus Torvalds char * from; 26561da177e4SLinus Torvalds char * to; 26571da177e4SLinus Torvalds 26581da177e4SLinus Torvalds from = getname(oldname); 26591da177e4SLinus Torvalds if(IS_ERR(from)) 26601da177e4SLinus Torvalds return PTR_ERR(from); 26611da177e4SLinus Torvalds to = getname(newname); 26621da177e4SLinus Torvalds error = PTR_ERR(to); 26631da177e4SLinus Torvalds if (!IS_ERR(to)) { 26645590ff0dSUlrich Drepper error = do_rename(olddfd, from, newdfd, to); 26651da177e4SLinus Torvalds putname(to); 26661da177e4SLinus Torvalds } 26671da177e4SLinus Torvalds putname(from); 26681da177e4SLinus Torvalds return error; 26691da177e4SLinus Torvalds } 26701da177e4SLinus Torvalds 26715590ff0dSUlrich Drepper asmlinkage long sys_rename(const char __user *oldname, const char __user *newname) 26725590ff0dSUlrich Drepper { 26735590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 26745590ff0dSUlrich Drepper } 26755590ff0dSUlrich Drepper 26761da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 26771da177e4SLinus Torvalds { 26781da177e4SLinus Torvalds int len; 26791da177e4SLinus Torvalds 26801da177e4SLinus Torvalds len = PTR_ERR(link); 26811da177e4SLinus Torvalds if (IS_ERR(link)) 26821da177e4SLinus Torvalds goto out; 26831da177e4SLinus Torvalds 26841da177e4SLinus Torvalds len = strlen(link); 26851da177e4SLinus Torvalds if (len > (unsigned) buflen) 26861da177e4SLinus Torvalds len = buflen; 26871da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 26881da177e4SLinus Torvalds len = -EFAULT; 26891da177e4SLinus Torvalds out: 26901da177e4SLinus Torvalds return len; 26911da177e4SLinus Torvalds } 26921da177e4SLinus Torvalds 26931da177e4SLinus Torvalds /* 26941da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 26951da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 26961da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 26971da177e4SLinus Torvalds */ 26981da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 26991da177e4SLinus Torvalds { 27001da177e4SLinus Torvalds struct nameidata nd; 2701cc314eefSLinus Torvalds void *cookie; 2702cc314eefSLinus Torvalds 27031da177e4SLinus Torvalds nd.depth = 0; 2704cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 2705cc314eefSLinus Torvalds if (!IS_ERR(cookie)) { 2706cc314eefSLinus Torvalds int res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 27071da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 2708cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 2709cc314eefSLinus Torvalds cookie = ERR_PTR(res); 27101da177e4SLinus Torvalds } 2711cc314eefSLinus Torvalds return PTR_ERR(cookie); 27121da177e4SLinus Torvalds } 27131da177e4SLinus Torvalds 27141da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 27151da177e4SLinus Torvalds { 27161da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 27171da177e4SLinus Torvalds } 27181da177e4SLinus Torvalds 27191da177e4SLinus Torvalds /* get the link contents into pagecache */ 27201da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 27211da177e4SLinus Torvalds { 27221da177e4SLinus Torvalds struct page * page; 27231da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 2724090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 27251da177e4SLinus Torvalds if (IS_ERR(page)) 27266fe6900eSNick Piggin return (char*)page; 27271da177e4SLinus Torvalds *ppage = page; 27281da177e4SLinus Torvalds return kmap(page); 27291da177e4SLinus Torvalds } 27301da177e4SLinus Torvalds 27311da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 27321da177e4SLinus Torvalds { 27331da177e4SLinus Torvalds struct page *page = NULL; 27341da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 27351da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 27361da177e4SLinus Torvalds if (page) { 27371da177e4SLinus Torvalds kunmap(page); 27381da177e4SLinus Torvalds page_cache_release(page); 27391da177e4SLinus Torvalds } 27401da177e4SLinus Torvalds return res; 27411da177e4SLinus Torvalds } 27421da177e4SLinus Torvalds 2743cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 27441da177e4SLinus Torvalds { 2745cc314eefSLinus Torvalds struct page *page = NULL; 27461da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 2747cc314eefSLinus Torvalds return page; 27481da177e4SLinus Torvalds } 27491da177e4SLinus Torvalds 2750cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 27511da177e4SLinus Torvalds { 2752cc314eefSLinus Torvalds struct page *page = cookie; 2753cc314eefSLinus Torvalds 2754cc314eefSLinus Torvalds if (page) { 27551da177e4SLinus Torvalds kunmap(page); 27561da177e4SLinus Torvalds page_cache_release(page); 27571da177e4SLinus Torvalds } 27581da177e4SLinus Torvalds } 27591da177e4SLinus Torvalds 27600adb25d2SKirill Korotaev int __page_symlink(struct inode *inode, const char *symname, int len, 27610adb25d2SKirill Korotaev gfp_t gfp_mask) 27621da177e4SLinus Torvalds { 27631da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 27640adb25d2SKirill Korotaev struct page *page; 2765afddba49SNick Piggin void *fsdata; 2766beb497abSDmitriy Monakhov int err; 27671da177e4SLinus Torvalds char *kaddr; 27681da177e4SLinus Torvalds 27697e53cac4SNeilBrown retry: 2770afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 2771afddba49SNick Piggin AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata); 27721da177e4SLinus Torvalds if (err) 2773afddba49SNick Piggin goto fail; 2774afddba49SNick Piggin 27751da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 27761da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 27771da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 2778afddba49SNick Piggin 2779afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 2780afddba49SNick Piggin page, fsdata); 27811da177e4SLinus Torvalds if (err < 0) 27821da177e4SLinus Torvalds goto fail; 2783afddba49SNick Piggin if (err < len-1) 2784afddba49SNick Piggin goto retry; 2785afddba49SNick Piggin 27861da177e4SLinus Torvalds mark_inode_dirty(inode); 27871da177e4SLinus Torvalds return 0; 27881da177e4SLinus Torvalds fail: 27891da177e4SLinus Torvalds return err; 27901da177e4SLinus Torvalds } 27911da177e4SLinus Torvalds 27920adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 27930adb25d2SKirill Korotaev { 27940adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 27950adb25d2SKirill Korotaev mapping_gfp_mask(inode->i_mapping)); 27960adb25d2SKirill Korotaev } 27970adb25d2SKirill Korotaev 279892e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 27991da177e4SLinus Torvalds .readlink = generic_readlink, 28001da177e4SLinus Torvalds .follow_link = page_follow_link_light, 28011da177e4SLinus Torvalds .put_link = page_put_link, 28021da177e4SLinus Torvalds }; 28031da177e4SLinus Torvalds 28041da177e4SLinus Torvalds EXPORT_SYMBOL(__user_walk); 28055590ff0dSUlrich Drepper EXPORT_SYMBOL(__user_walk_fd); 28061da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 28071da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 28081da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 28091da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 28101da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 28111da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 28121da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 28131da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 28141da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 28150adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 28161da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 28171da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 28181da177e4SLinus Torvalds EXPORT_SYMBOL(path_lookup); 281916f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 28201da177e4SLinus Torvalds EXPORT_SYMBOL(permission); 2821e4543eddSChristoph Hellwig EXPORT_SYMBOL(vfs_permission); 28228c744fb8SChristoph Hellwig EXPORT_SYMBOL(file_permission); 28231da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 28241da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 28251da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 28261da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 28271da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 28281da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 28291da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 28301da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 28311da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 28321da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 28331da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 28341da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 28351da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 28361da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 2837