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 /** 3665dd784d0SJan Blunck * path_get - get a reference to a path 3675dd784d0SJan Blunck * @path: path to get the reference to 3685dd784d0SJan Blunck * 3695dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 3705dd784d0SJan Blunck */ 3715dd784d0SJan Blunck void path_get(struct path *path) 3725dd784d0SJan Blunck { 3735dd784d0SJan Blunck mntget(path->mnt); 3745dd784d0SJan Blunck dget(path->dentry); 3755dd784d0SJan Blunck } 3765dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 3775dd784d0SJan Blunck 3785dd784d0SJan Blunck /** 3791d957f9bSJan Blunck * path_put - put a reference to a path 3801d957f9bSJan Blunck * @path: path to put the reference to 3811d957f9bSJan Blunck * 3821d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 3831d957f9bSJan Blunck */ 3841d957f9bSJan Blunck void path_put(struct path *path) 3851da177e4SLinus Torvalds { 3861d957f9bSJan Blunck dput(path->dentry); 3871d957f9bSJan Blunck mntput(path->mnt); 3881da177e4SLinus Torvalds } 3891d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 3901da177e4SLinus Torvalds 391834f2a4aSTrond Myklebust /** 392834f2a4aSTrond Myklebust * release_open_intent - free up open intent resources 393834f2a4aSTrond Myklebust * @nd: pointer to nameidata 394834f2a4aSTrond Myklebust */ 395834f2a4aSTrond Myklebust void release_open_intent(struct nameidata *nd) 396834f2a4aSTrond Myklebust { 3970f7fc9e4SJosef "Jeff" Sipek if (nd->intent.open.file->f_path.dentry == NULL) 398834f2a4aSTrond Myklebust put_filp(nd->intent.open.file); 399834f2a4aSTrond Myklebust else 400834f2a4aSTrond Myklebust fput(nd->intent.open.file); 401834f2a4aSTrond Myklebust } 402834f2a4aSTrond Myklebust 403bcdc5e01SIan Kent static inline struct dentry * 404bcdc5e01SIan Kent do_revalidate(struct dentry *dentry, struct nameidata *nd) 405bcdc5e01SIan Kent { 406bcdc5e01SIan Kent int status = dentry->d_op->d_revalidate(dentry, nd); 407bcdc5e01SIan Kent if (unlikely(status <= 0)) { 408bcdc5e01SIan Kent /* 409bcdc5e01SIan Kent * The dentry failed validation. 410bcdc5e01SIan Kent * If d_revalidate returned 0 attempt to invalidate 411bcdc5e01SIan Kent * the dentry otherwise d_revalidate is asking us 412bcdc5e01SIan Kent * to return a fail status. 413bcdc5e01SIan Kent */ 414bcdc5e01SIan Kent if (!status) { 415bcdc5e01SIan Kent if (!d_invalidate(dentry)) { 416bcdc5e01SIan Kent dput(dentry); 417bcdc5e01SIan Kent dentry = NULL; 418bcdc5e01SIan Kent } 419bcdc5e01SIan Kent } else { 420bcdc5e01SIan Kent dput(dentry); 421bcdc5e01SIan Kent dentry = ERR_PTR(status); 422bcdc5e01SIan Kent } 423bcdc5e01SIan Kent } 424bcdc5e01SIan Kent return dentry; 425bcdc5e01SIan Kent } 426bcdc5e01SIan Kent 4271da177e4SLinus Torvalds /* 4281da177e4SLinus Torvalds * Internal lookup() using the new generic dcache. 4291da177e4SLinus Torvalds * SMP-safe 4301da177e4SLinus Torvalds */ 4311da177e4SLinus Torvalds static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) 4321da177e4SLinus Torvalds { 4331da177e4SLinus Torvalds struct dentry * dentry = __d_lookup(parent, name); 4341da177e4SLinus Torvalds 4351da177e4SLinus Torvalds /* lockess __d_lookup may fail due to concurrent d_move() 4361da177e4SLinus Torvalds * in some unrelated directory, so try with d_lookup 4371da177e4SLinus Torvalds */ 4381da177e4SLinus Torvalds if (!dentry) 4391da177e4SLinus Torvalds dentry = d_lookup(parent, name); 4401da177e4SLinus Torvalds 441bcdc5e01SIan Kent if (dentry && dentry->d_op && dentry->d_op->d_revalidate) 442bcdc5e01SIan Kent dentry = do_revalidate(dentry, nd); 443bcdc5e01SIan Kent 4441da177e4SLinus Torvalds return dentry; 4451da177e4SLinus Torvalds } 4461da177e4SLinus Torvalds 4471da177e4SLinus Torvalds /* 4481da177e4SLinus Torvalds * Short-cut version of permission(), for calling by 4491da177e4SLinus Torvalds * path_walk(), when dcache lock is held. Combines parts 4501da177e4SLinus Torvalds * of permission() and generic_permission(), and tests ONLY for 4511da177e4SLinus Torvalds * MAY_EXEC permission. 4521da177e4SLinus Torvalds * 4531da177e4SLinus Torvalds * If appropriate, check DAC only. If not appropriate, or 4541da177e4SLinus Torvalds * short-cut DAC fails, then call permission() to do more 4551da177e4SLinus Torvalds * complete permission check. 4561da177e4SLinus Torvalds */ 457858119e1SArjan van de Ven static int exec_permission_lite(struct inode *inode, 4581da177e4SLinus Torvalds struct nameidata *nd) 4591da177e4SLinus Torvalds { 4601da177e4SLinus Torvalds umode_t mode = inode->i_mode; 4611da177e4SLinus Torvalds 4621da177e4SLinus Torvalds if (inode->i_op && inode->i_op->permission) 4631da177e4SLinus Torvalds return -EAGAIN; 4641da177e4SLinus Torvalds 4651da177e4SLinus Torvalds if (current->fsuid == inode->i_uid) 4661da177e4SLinus Torvalds mode >>= 6; 4671da177e4SLinus Torvalds else if (in_group_p(inode->i_gid)) 4681da177e4SLinus Torvalds mode >>= 3; 4691da177e4SLinus Torvalds 4701da177e4SLinus Torvalds if (mode & MAY_EXEC) 4711da177e4SLinus Torvalds goto ok; 4721da177e4SLinus Torvalds 4731da177e4SLinus Torvalds if ((inode->i_mode & S_IXUGO) && capable(CAP_DAC_OVERRIDE)) 4741da177e4SLinus Torvalds goto ok; 4751da177e4SLinus Torvalds 4761da177e4SLinus Torvalds if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_OVERRIDE)) 4771da177e4SLinus Torvalds goto ok; 4781da177e4SLinus Torvalds 4791da177e4SLinus Torvalds if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_READ_SEARCH)) 4801da177e4SLinus Torvalds goto ok; 4811da177e4SLinus Torvalds 4821da177e4SLinus Torvalds return -EACCES; 4831da177e4SLinus Torvalds ok: 4841da177e4SLinus Torvalds return security_inode_permission(inode, MAY_EXEC, nd); 4851da177e4SLinus Torvalds } 4861da177e4SLinus Torvalds 4871da177e4SLinus Torvalds /* 4881da177e4SLinus Torvalds * This is called when everything else fails, and we actually have 4891da177e4SLinus Torvalds * to go to the low-level filesystem to find out what we should do.. 4901da177e4SLinus Torvalds * 4911da177e4SLinus Torvalds * We get the directory semaphore, and after getting that we also 4921da177e4SLinus Torvalds * make sure that nobody added the entry to the dcache in the meantime.. 4931da177e4SLinus Torvalds * SMP-safe 4941da177e4SLinus Torvalds */ 4951da177e4SLinus Torvalds static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) 4961da177e4SLinus Torvalds { 4971da177e4SLinus Torvalds struct dentry * result; 4981da177e4SLinus Torvalds struct inode *dir = parent->d_inode; 4991da177e4SLinus Torvalds 5001b1dcc1bSJes Sorensen mutex_lock(&dir->i_mutex); 5011da177e4SLinus Torvalds /* 5021da177e4SLinus Torvalds * First re-do the cached lookup just in case it was created 5031da177e4SLinus Torvalds * while we waited for the directory semaphore.. 5041da177e4SLinus Torvalds * 5051da177e4SLinus Torvalds * FIXME! This could use version numbering or similar to 5061da177e4SLinus Torvalds * avoid unnecessary cache lookups. 5071da177e4SLinus Torvalds * 5081da177e4SLinus Torvalds * The "dcache_lock" is purely to protect the RCU list walker 5091da177e4SLinus Torvalds * from concurrent renames at this point (we mustn't get false 5101da177e4SLinus Torvalds * negatives from the RCU list walk here, unlike the optimistic 5111da177e4SLinus Torvalds * fast walk). 5121da177e4SLinus Torvalds * 5131da177e4SLinus Torvalds * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup 5141da177e4SLinus Torvalds */ 5151da177e4SLinus Torvalds result = d_lookup(parent, name); 5161da177e4SLinus Torvalds if (!result) { 5171da177e4SLinus Torvalds struct dentry * dentry = d_alloc(parent, name); 5181da177e4SLinus Torvalds result = ERR_PTR(-ENOMEM); 5191da177e4SLinus Torvalds if (dentry) { 5201da177e4SLinus Torvalds result = dir->i_op->lookup(dir, dentry, nd); 5211da177e4SLinus Torvalds if (result) 5221da177e4SLinus Torvalds dput(dentry); 5231da177e4SLinus Torvalds else 5241da177e4SLinus Torvalds result = dentry; 5251da177e4SLinus Torvalds } 5261b1dcc1bSJes Sorensen mutex_unlock(&dir->i_mutex); 5271da177e4SLinus Torvalds return result; 5281da177e4SLinus Torvalds } 5291da177e4SLinus Torvalds 5301da177e4SLinus Torvalds /* 5311da177e4SLinus Torvalds * Uhhuh! Nasty case: the cache was re-populated while 5321da177e4SLinus Torvalds * we waited on the semaphore. Need to revalidate. 5331da177e4SLinus Torvalds */ 5341b1dcc1bSJes Sorensen mutex_unlock(&dir->i_mutex); 5351da177e4SLinus Torvalds if (result->d_op && result->d_op->d_revalidate) { 536bcdc5e01SIan Kent result = do_revalidate(result, nd); 537bcdc5e01SIan Kent if (!result) 5381da177e4SLinus Torvalds result = ERR_PTR(-ENOENT); 5391da177e4SLinus Torvalds } 5401da177e4SLinus Torvalds return result; 5411da177e4SLinus Torvalds } 5421da177e4SLinus Torvalds 5431da177e4SLinus Torvalds static int __emul_lookup_dentry(const char *, struct nameidata *); 5441da177e4SLinus Torvalds 5451da177e4SLinus Torvalds /* SMP-safe */ 546f1662356SArjan van de Ven static __always_inline int 5471da177e4SLinus Torvalds walk_init_root(const char *name, struct nameidata *nd) 5481da177e4SLinus Torvalds { 549e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 550e518ddb7SAndreas Mohr 551e518ddb7SAndreas Mohr read_lock(&fs->lock); 5526ac08c39SJan Blunck if (fs->altroot.dentry && !(nd->flags & LOOKUP_NOALT)) { 5536ac08c39SJan Blunck nd->path = fs->altroot; 5546ac08c39SJan Blunck path_get(&fs->altroot); 555e518ddb7SAndreas Mohr read_unlock(&fs->lock); 5561da177e4SLinus Torvalds if (__emul_lookup_dentry(name,nd)) 5571da177e4SLinus Torvalds return 0; 558e518ddb7SAndreas Mohr read_lock(&fs->lock); 5591da177e4SLinus Torvalds } 5606ac08c39SJan Blunck nd->path = fs->root; 5616ac08c39SJan Blunck path_get(&fs->root); 562e518ddb7SAndreas Mohr read_unlock(&fs->lock); 5631da177e4SLinus Torvalds return 1; 5641da177e4SLinus Torvalds } 5651da177e4SLinus Torvalds 566f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 5671da177e4SLinus Torvalds { 5681da177e4SLinus Torvalds int res = 0; 5691da177e4SLinus Torvalds char *name; 5701da177e4SLinus Torvalds if (IS_ERR(link)) 5711da177e4SLinus Torvalds goto fail; 5721da177e4SLinus Torvalds 5731da177e4SLinus Torvalds if (*link == '/') { 5741d957f9bSJan Blunck path_put(&nd->path); 5751da177e4SLinus Torvalds if (!walk_init_root(link, nd)) 5761da177e4SLinus Torvalds /* weird __emul_prefix() stuff did it */ 5771da177e4SLinus Torvalds goto out; 5781da177e4SLinus Torvalds } 5791da177e4SLinus Torvalds res = link_path_walk(link, nd); 5801da177e4SLinus Torvalds out: 5811da177e4SLinus Torvalds if (nd->depth || res || nd->last_type!=LAST_NORM) 5821da177e4SLinus Torvalds return res; 5831da177e4SLinus Torvalds /* 5841da177e4SLinus Torvalds * If it is an iterative symlinks resolution in open_namei() we 5851da177e4SLinus Torvalds * have to copy the last component. And all that crap because of 5861da177e4SLinus Torvalds * bloody create() on broken symlinks. Furrfu... 5871da177e4SLinus Torvalds */ 5881da177e4SLinus Torvalds name = __getname(); 5891da177e4SLinus Torvalds if (unlikely(!name)) { 5901d957f9bSJan Blunck path_put(&nd->path); 5911da177e4SLinus Torvalds return -ENOMEM; 5921da177e4SLinus Torvalds } 5931da177e4SLinus Torvalds strcpy(name, nd->last.name); 5941da177e4SLinus Torvalds nd->last.name = name; 5951da177e4SLinus Torvalds return 0; 5961da177e4SLinus Torvalds fail: 5971d957f9bSJan Blunck path_put(&nd->path); 5981da177e4SLinus Torvalds return PTR_ERR(link); 5991da177e4SLinus Torvalds } 6001da177e4SLinus Torvalds 6011d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 602051d3812SIan Kent { 603051d3812SIan Kent dput(path->dentry); 6044ac91378SJan Blunck if (path->mnt != nd->path.mnt) 605051d3812SIan Kent mntput(path->mnt); 606051d3812SIan Kent } 607051d3812SIan Kent 608051d3812SIan Kent static inline void path_to_nameidata(struct path *path, struct nameidata *nd) 609051d3812SIan Kent { 6104ac91378SJan Blunck dput(nd->path.dentry); 6114ac91378SJan Blunck if (nd->path.mnt != path->mnt) 6124ac91378SJan Blunck mntput(nd->path.mnt); 6134ac91378SJan Blunck nd->path.mnt = path->mnt; 6144ac91378SJan Blunck nd->path.dentry = path->dentry; 615051d3812SIan Kent } 616051d3812SIan Kent 617f1662356SArjan van de Ven static __always_inline int __do_follow_link(struct path *path, struct nameidata *nd) 6181da177e4SLinus Torvalds { 6191da177e4SLinus Torvalds int error; 620cc314eefSLinus Torvalds void *cookie; 621cd4e91d3SAl Viro struct dentry *dentry = path->dentry; 6221da177e4SLinus Torvalds 623d671a1cbSAl Viro touch_atime(path->mnt, dentry); 6241da177e4SLinus Torvalds nd_set_link(nd, NULL); 625cd4e91d3SAl Viro 6264ac91378SJan Blunck if (path->mnt != nd->path.mnt) { 627051d3812SIan Kent path_to_nameidata(path, nd); 628051d3812SIan Kent dget(dentry); 629051d3812SIan Kent } 630cd4e91d3SAl Viro mntget(path->mnt); 631cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, nd); 632cc314eefSLinus Torvalds error = PTR_ERR(cookie); 633cc314eefSLinus Torvalds if (!IS_ERR(cookie)) { 6341da177e4SLinus Torvalds char *s = nd_get_link(nd); 635cc314eefSLinus Torvalds error = 0; 6361da177e4SLinus Torvalds if (s) 6371da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 6381da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 639cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, nd, cookie); 6401da177e4SLinus Torvalds } 64109da5916SJan Blunck path_put(path); 6421da177e4SLinus Torvalds 6431da177e4SLinus Torvalds return error; 6441da177e4SLinus Torvalds } 6451da177e4SLinus Torvalds 6461da177e4SLinus Torvalds /* 6471da177e4SLinus Torvalds * This limits recursive symlink follows to 8, while 6481da177e4SLinus Torvalds * limiting consecutive symlinks to 40. 6491da177e4SLinus Torvalds * 6501da177e4SLinus Torvalds * Without that kind of total limit, nasty chains of consecutive 6511da177e4SLinus Torvalds * symlinks can cause almost arbitrarily long lookups. 6521da177e4SLinus Torvalds */ 65390ebe565SAl Viro static inline int do_follow_link(struct path *path, struct nameidata *nd) 6541da177e4SLinus Torvalds { 6551da177e4SLinus Torvalds int err = -ELOOP; 6561da177e4SLinus Torvalds if (current->link_count >= MAX_NESTED_LINKS) 6571da177e4SLinus Torvalds goto loop; 6581da177e4SLinus Torvalds if (current->total_link_count >= 40) 6591da177e4SLinus Torvalds goto loop; 6601da177e4SLinus Torvalds BUG_ON(nd->depth >= MAX_NESTED_LINKS); 6611da177e4SLinus Torvalds cond_resched(); 66290ebe565SAl Viro err = security_inode_follow_link(path->dentry, nd); 6631da177e4SLinus Torvalds if (err) 6641da177e4SLinus Torvalds goto loop; 6651da177e4SLinus Torvalds current->link_count++; 6661da177e4SLinus Torvalds current->total_link_count++; 6671da177e4SLinus Torvalds nd->depth++; 668cd4e91d3SAl Viro err = __do_follow_link(path, nd); 6691da177e4SLinus Torvalds current->link_count--; 6701da177e4SLinus Torvalds nd->depth--; 6711da177e4SLinus Torvalds return err; 6721da177e4SLinus Torvalds loop: 6731d957f9bSJan Blunck path_put_conditional(path, nd); 6741d957f9bSJan Blunck path_put(&nd->path); 6751da177e4SLinus Torvalds return err; 6761da177e4SLinus Torvalds } 6771da177e4SLinus Torvalds 6781da177e4SLinus Torvalds int follow_up(struct vfsmount **mnt, struct dentry **dentry) 6791da177e4SLinus Torvalds { 6801da177e4SLinus Torvalds struct vfsmount *parent; 6811da177e4SLinus Torvalds struct dentry *mountpoint; 6821da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 6831da177e4SLinus Torvalds parent=(*mnt)->mnt_parent; 6841da177e4SLinus Torvalds if (parent == *mnt) { 6851da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 6861da177e4SLinus Torvalds return 0; 6871da177e4SLinus Torvalds } 6881da177e4SLinus Torvalds mntget(parent); 6891da177e4SLinus Torvalds mountpoint=dget((*mnt)->mnt_mountpoint); 6901da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 6911da177e4SLinus Torvalds dput(*dentry); 6921da177e4SLinus Torvalds *dentry = mountpoint; 6931da177e4SLinus Torvalds mntput(*mnt); 6941da177e4SLinus Torvalds *mnt = parent; 6951da177e4SLinus Torvalds return 1; 6961da177e4SLinus Torvalds } 6971da177e4SLinus Torvalds 6981da177e4SLinus Torvalds /* no need for dcache_lock, as serialization is taken care in 6991da177e4SLinus Torvalds * namespace.c 7001da177e4SLinus Torvalds */ 701463ffb2eSAl Viro static int __follow_mount(struct path *path) 702463ffb2eSAl Viro { 703463ffb2eSAl Viro int res = 0; 704463ffb2eSAl Viro while (d_mountpoint(path->dentry)) { 705463ffb2eSAl Viro struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry); 706463ffb2eSAl Viro if (!mounted) 707463ffb2eSAl Viro break; 708463ffb2eSAl Viro dput(path->dentry); 709463ffb2eSAl Viro if (res) 710463ffb2eSAl Viro mntput(path->mnt); 711463ffb2eSAl Viro path->mnt = mounted; 712463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 713463ffb2eSAl Viro res = 1; 714463ffb2eSAl Viro } 715463ffb2eSAl Viro return res; 716463ffb2eSAl Viro } 717463ffb2eSAl Viro 71858c465ebSAl Viro static void follow_mount(struct vfsmount **mnt, struct dentry **dentry) 7191da177e4SLinus Torvalds { 7201da177e4SLinus Torvalds while (d_mountpoint(*dentry)) { 7211da177e4SLinus Torvalds struct vfsmount *mounted = lookup_mnt(*mnt, *dentry); 7221da177e4SLinus Torvalds if (!mounted) 7231da177e4SLinus Torvalds break; 72458c465ebSAl Viro dput(*dentry); 7251da177e4SLinus Torvalds mntput(*mnt); 7261da177e4SLinus Torvalds *mnt = mounted; 7271da177e4SLinus Torvalds *dentry = dget(mounted->mnt_root); 7281da177e4SLinus Torvalds } 7291da177e4SLinus Torvalds } 7301da177e4SLinus Torvalds 7311da177e4SLinus Torvalds /* no need for dcache_lock, as serialization is taken care in 7321da177e4SLinus Torvalds * namespace.c 7331da177e4SLinus Torvalds */ 734e13b210fSAl Viro int follow_down(struct vfsmount **mnt, struct dentry **dentry) 7351da177e4SLinus Torvalds { 7361da177e4SLinus Torvalds struct vfsmount *mounted; 7371da177e4SLinus Torvalds 7381da177e4SLinus Torvalds mounted = lookup_mnt(*mnt, *dentry); 7391da177e4SLinus Torvalds if (mounted) { 740e13b210fSAl Viro dput(*dentry); 7411da177e4SLinus Torvalds mntput(*mnt); 7421da177e4SLinus Torvalds *mnt = mounted; 7431da177e4SLinus Torvalds *dentry = dget(mounted->mnt_root); 7441da177e4SLinus Torvalds return 1; 7451da177e4SLinus Torvalds } 7461da177e4SLinus Torvalds return 0; 7471da177e4SLinus Torvalds } 7481da177e4SLinus Torvalds 749f1662356SArjan van de Ven static __always_inline void follow_dotdot(struct nameidata *nd) 7501da177e4SLinus Torvalds { 751e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 752e518ddb7SAndreas Mohr 7531da177e4SLinus Torvalds while(1) { 7541da177e4SLinus Torvalds struct vfsmount *parent; 7554ac91378SJan Blunck struct dentry *old = nd->path.dentry; 7561da177e4SLinus Torvalds 757e518ddb7SAndreas Mohr read_lock(&fs->lock); 7586ac08c39SJan Blunck if (nd->path.dentry == fs->root.dentry && 7596ac08c39SJan Blunck nd->path.mnt == fs->root.mnt) { 760e518ddb7SAndreas Mohr read_unlock(&fs->lock); 7611da177e4SLinus Torvalds break; 7621da177e4SLinus Torvalds } 763e518ddb7SAndreas Mohr read_unlock(&fs->lock); 7641da177e4SLinus Torvalds spin_lock(&dcache_lock); 7654ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 7664ac91378SJan Blunck nd->path.dentry = dget(nd->path.dentry->d_parent); 7671da177e4SLinus Torvalds spin_unlock(&dcache_lock); 7681da177e4SLinus Torvalds dput(old); 7691da177e4SLinus Torvalds break; 7701da177e4SLinus Torvalds } 7711da177e4SLinus Torvalds spin_unlock(&dcache_lock); 7721da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 7734ac91378SJan Blunck parent = nd->path.mnt->mnt_parent; 7744ac91378SJan Blunck if (parent == nd->path.mnt) { 7751da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7761da177e4SLinus Torvalds break; 7771da177e4SLinus Torvalds } 7781da177e4SLinus Torvalds mntget(parent); 7794ac91378SJan Blunck nd->path.dentry = dget(nd->path.mnt->mnt_mountpoint); 7801da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7811da177e4SLinus Torvalds dput(old); 7824ac91378SJan Blunck mntput(nd->path.mnt); 7834ac91378SJan Blunck nd->path.mnt = parent; 7841da177e4SLinus Torvalds } 7854ac91378SJan Blunck follow_mount(&nd->path.mnt, &nd->path.dentry); 7861da177e4SLinus Torvalds } 7871da177e4SLinus Torvalds 7881da177e4SLinus Torvalds /* 7891da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 7901da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 7911da177e4SLinus Torvalds * It _is_ time-critical. 7921da177e4SLinus Torvalds */ 7931da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 7941da177e4SLinus Torvalds struct path *path) 7951da177e4SLinus Torvalds { 7964ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 7974ac91378SJan Blunck struct dentry *dentry = __d_lookup(nd->path.dentry, name); 7981da177e4SLinus Torvalds 7991da177e4SLinus Torvalds if (!dentry) 8001da177e4SLinus Torvalds goto need_lookup; 8011da177e4SLinus Torvalds if (dentry->d_op && dentry->d_op->d_revalidate) 8021da177e4SLinus Torvalds goto need_revalidate; 8031da177e4SLinus Torvalds done: 8041da177e4SLinus Torvalds path->mnt = mnt; 8051da177e4SLinus Torvalds path->dentry = dentry; 806634ee701SAl Viro __follow_mount(path); 8071da177e4SLinus Torvalds return 0; 8081da177e4SLinus Torvalds 8091da177e4SLinus Torvalds need_lookup: 8104ac91378SJan Blunck dentry = real_lookup(nd->path.dentry, name, nd); 8111da177e4SLinus Torvalds if (IS_ERR(dentry)) 8121da177e4SLinus Torvalds goto fail; 8131da177e4SLinus Torvalds goto done; 8141da177e4SLinus Torvalds 8151da177e4SLinus Torvalds need_revalidate: 816bcdc5e01SIan Kent dentry = do_revalidate(dentry, nd); 817bcdc5e01SIan Kent if (!dentry) 8181da177e4SLinus Torvalds goto need_lookup; 819bcdc5e01SIan Kent if (IS_ERR(dentry)) 820bcdc5e01SIan Kent goto fail; 821bcdc5e01SIan Kent goto done; 8221da177e4SLinus Torvalds 8231da177e4SLinus Torvalds fail: 8241da177e4SLinus Torvalds return PTR_ERR(dentry); 8251da177e4SLinus Torvalds } 8261da177e4SLinus Torvalds 8271da177e4SLinus Torvalds /* 8281da177e4SLinus Torvalds * Name resolution. 829ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 830ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 8311da177e4SLinus Torvalds * 832ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 833ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 8341da177e4SLinus Torvalds */ 835fc9b52cdSHarvey Harrison static int __link_path_walk(const char *name, struct nameidata *nd) 8361da177e4SLinus Torvalds { 8371da177e4SLinus Torvalds struct path next; 8381da177e4SLinus Torvalds struct inode *inode; 8391da177e4SLinus Torvalds int err; 8401da177e4SLinus Torvalds unsigned int lookup_flags = nd->flags; 8411da177e4SLinus Torvalds 8421da177e4SLinus Torvalds while (*name=='/') 8431da177e4SLinus Torvalds name++; 8441da177e4SLinus Torvalds if (!*name) 8451da177e4SLinus Torvalds goto return_reval; 8461da177e4SLinus Torvalds 8474ac91378SJan Blunck inode = nd->path.dentry->d_inode; 8481da177e4SLinus Torvalds if (nd->depth) 849f55eab82STrond Myklebust lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE); 8501da177e4SLinus Torvalds 8511da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 8521da177e4SLinus Torvalds for(;;) { 8531da177e4SLinus Torvalds unsigned long hash; 8541da177e4SLinus Torvalds struct qstr this; 8551da177e4SLinus Torvalds unsigned int c; 8561da177e4SLinus Torvalds 857cdce5d6bSTrond Myklebust nd->flags |= LOOKUP_CONTINUE; 8581da177e4SLinus Torvalds err = exec_permission_lite(inode, nd); 859e4543eddSChristoph Hellwig if (err == -EAGAIN) 860e4543eddSChristoph Hellwig err = vfs_permission(nd, MAY_EXEC); 8611da177e4SLinus Torvalds if (err) 8621da177e4SLinus Torvalds break; 8631da177e4SLinus Torvalds 8641da177e4SLinus Torvalds this.name = name; 8651da177e4SLinus Torvalds c = *(const unsigned char *)name; 8661da177e4SLinus Torvalds 8671da177e4SLinus Torvalds hash = init_name_hash(); 8681da177e4SLinus Torvalds do { 8691da177e4SLinus Torvalds name++; 8701da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 8711da177e4SLinus Torvalds c = *(const unsigned char *)name; 8721da177e4SLinus Torvalds } while (c && (c != '/')); 8731da177e4SLinus Torvalds this.len = name - (const char *) this.name; 8741da177e4SLinus Torvalds this.hash = end_name_hash(hash); 8751da177e4SLinus Torvalds 8761da177e4SLinus Torvalds /* remove trailing slashes? */ 8771da177e4SLinus Torvalds if (!c) 8781da177e4SLinus Torvalds goto last_component; 8791da177e4SLinus Torvalds while (*++name == '/'); 8801da177e4SLinus Torvalds if (!*name) 8811da177e4SLinus Torvalds goto last_with_slashes; 8821da177e4SLinus Torvalds 8831da177e4SLinus Torvalds /* 8841da177e4SLinus Torvalds * "." and ".." are special - ".." especially so because it has 8851da177e4SLinus Torvalds * to be able to know about the current root directory and 8861da177e4SLinus Torvalds * parent relationships. 8871da177e4SLinus Torvalds */ 8881da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 8891da177e4SLinus Torvalds default: 8901da177e4SLinus Torvalds break; 8911da177e4SLinus Torvalds case 2: 8921da177e4SLinus Torvalds if (this.name[1] != '.') 8931da177e4SLinus Torvalds break; 89458c465ebSAl Viro follow_dotdot(nd); 8954ac91378SJan Blunck inode = nd->path.dentry->d_inode; 8961da177e4SLinus Torvalds /* fallthrough */ 8971da177e4SLinus Torvalds case 1: 8981da177e4SLinus Torvalds continue; 8991da177e4SLinus Torvalds } 9001da177e4SLinus Torvalds /* 9011da177e4SLinus Torvalds * See if the low-level filesystem might want 9021da177e4SLinus Torvalds * to use its own hash.. 9031da177e4SLinus Torvalds */ 9044ac91378SJan Blunck if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { 9054ac91378SJan Blunck err = nd->path.dentry->d_op->d_hash(nd->path.dentry, 9064ac91378SJan Blunck &this); 9071da177e4SLinus Torvalds if (err < 0) 9081da177e4SLinus Torvalds break; 9091da177e4SLinus Torvalds } 9101da177e4SLinus Torvalds /* This does the actual lookups.. */ 9111da177e4SLinus Torvalds err = do_lookup(nd, &this, &next); 9121da177e4SLinus Torvalds if (err) 9131da177e4SLinus Torvalds break; 9141da177e4SLinus Torvalds 9151da177e4SLinus Torvalds err = -ENOENT; 9161da177e4SLinus Torvalds inode = next.dentry->d_inode; 9171da177e4SLinus Torvalds if (!inode) 9181da177e4SLinus Torvalds goto out_dput; 9191da177e4SLinus Torvalds err = -ENOTDIR; 9201da177e4SLinus Torvalds if (!inode->i_op) 9211da177e4SLinus Torvalds goto out_dput; 9221da177e4SLinus Torvalds 9231da177e4SLinus Torvalds if (inode->i_op->follow_link) { 92490ebe565SAl Viro err = do_follow_link(&next, nd); 9251da177e4SLinus Torvalds if (err) 9261da177e4SLinus Torvalds goto return_err; 9271da177e4SLinus Torvalds err = -ENOENT; 9284ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9291da177e4SLinus Torvalds if (!inode) 9301da177e4SLinus Torvalds break; 9311da177e4SLinus Torvalds err = -ENOTDIR; 9321da177e4SLinus Torvalds if (!inode->i_op) 9331da177e4SLinus Torvalds break; 93409dd17d3SMiklos Szeredi } else 93509dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 9361da177e4SLinus Torvalds err = -ENOTDIR; 9371da177e4SLinus Torvalds if (!inode->i_op->lookup) 9381da177e4SLinus Torvalds break; 9391da177e4SLinus Torvalds continue; 9401da177e4SLinus Torvalds /* here ends the main loop */ 9411da177e4SLinus Torvalds 9421da177e4SLinus Torvalds last_with_slashes: 9431da177e4SLinus Torvalds lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 9441da177e4SLinus Torvalds last_component: 945f55eab82STrond Myklebust /* Clear LOOKUP_CONTINUE iff it was previously unset */ 946f55eab82STrond Myklebust nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; 9471da177e4SLinus Torvalds if (lookup_flags & LOOKUP_PARENT) 9481da177e4SLinus Torvalds goto lookup_parent; 9491da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 9501da177e4SLinus Torvalds default: 9511da177e4SLinus Torvalds break; 9521da177e4SLinus Torvalds case 2: 9531da177e4SLinus Torvalds if (this.name[1] != '.') 9541da177e4SLinus Torvalds break; 95558c465ebSAl Viro follow_dotdot(nd); 9564ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9571da177e4SLinus Torvalds /* fallthrough */ 9581da177e4SLinus Torvalds case 1: 9591da177e4SLinus Torvalds goto return_reval; 9601da177e4SLinus Torvalds } 9614ac91378SJan Blunck if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { 9624ac91378SJan Blunck err = nd->path.dentry->d_op->d_hash(nd->path.dentry, 9634ac91378SJan Blunck &this); 9641da177e4SLinus Torvalds if (err < 0) 9651da177e4SLinus Torvalds break; 9661da177e4SLinus Torvalds } 9671da177e4SLinus Torvalds err = do_lookup(nd, &this, &next); 9681da177e4SLinus Torvalds if (err) 9691da177e4SLinus Torvalds break; 9701da177e4SLinus Torvalds inode = next.dentry->d_inode; 9711da177e4SLinus Torvalds if ((lookup_flags & LOOKUP_FOLLOW) 9721da177e4SLinus Torvalds && inode && inode->i_op && inode->i_op->follow_link) { 97390ebe565SAl Viro err = do_follow_link(&next, nd); 9741da177e4SLinus Torvalds if (err) 9751da177e4SLinus Torvalds goto return_err; 9764ac91378SJan Blunck inode = nd->path.dentry->d_inode; 97709dd17d3SMiklos Szeredi } else 97809dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 9791da177e4SLinus Torvalds err = -ENOENT; 9801da177e4SLinus Torvalds if (!inode) 9811da177e4SLinus Torvalds break; 9821da177e4SLinus Torvalds if (lookup_flags & LOOKUP_DIRECTORY) { 9831da177e4SLinus Torvalds err = -ENOTDIR; 9841da177e4SLinus Torvalds if (!inode->i_op || !inode->i_op->lookup) 9851da177e4SLinus Torvalds break; 9861da177e4SLinus Torvalds } 9871da177e4SLinus Torvalds goto return_base; 9881da177e4SLinus Torvalds lookup_parent: 9891da177e4SLinus Torvalds nd->last = this; 9901da177e4SLinus Torvalds nd->last_type = LAST_NORM; 9911da177e4SLinus Torvalds if (this.name[0] != '.') 9921da177e4SLinus Torvalds goto return_base; 9931da177e4SLinus Torvalds if (this.len == 1) 9941da177e4SLinus Torvalds nd->last_type = LAST_DOT; 9951da177e4SLinus Torvalds else if (this.len == 2 && this.name[1] == '.') 9961da177e4SLinus Torvalds nd->last_type = LAST_DOTDOT; 9971da177e4SLinus Torvalds else 9981da177e4SLinus Torvalds goto return_base; 9991da177e4SLinus Torvalds return_reval: 10001da177e4SLinus Torvalds /* 10011da177e4SLinus Torvalds * We bypassed the ordinary revalidation routines. 10021da177e4SLinus Torvalds * We may need to check the cached dentry for staleness. 10031da177e4SLinus Torvalds */ 10044ac91378SJan Blunck if (nd->path.dentry && nd->path.dentry->d_sb && 10054ac91378SJan Blunck (nd->path.dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) { 10061da177e4SLinus Torvalds err = -ESTALE; 10071da177e4SLinus Torvalds /* Note: we do not d_invalidate() */ 10084ac91378SJan Blunck if (!nd->path.dentry->d_op->d_revalidate( 10094ac91378SJan Blunck nd->path.dentry, nd)) 10101da177e4SLinus Torvalds break; 10111da177e4SLinus Torvalds } 10121da177e4SLinus Torvalds return_base: 10131da177e4SLinus Torvalds return 0; 10141da177e4SLinus Torvalds out_dput: 10151d957f9bSJan Blunck path_put_conditional(&next, nd); 10161da177e4SLinus Torvalds break; 10171da177e4SLinus Torvalds } 10181d957f9bSJan Blunck path_put(&nd->path); 10191da177e4SLinus Torvalds return_err: 10201da177e4SLinus Torvalds return err; 10211da177e4SLinus Torvalds } 10221da177e4SLinus Torvalds 10231da177e4SLinus Torvalds /* 10241da177e4SLinus Torvalds * Wrapper to retry pathname resolution whenever the underlying 10251da177e4SLinus Torvalds * file system returns an ESTALE. 10261da177e4SLinus Torvalds * 10271da177e4SLinus Torvalds * Retry the whole path once, forcing real lookup requests 10281da177e4SLinus Torvalds * instead of relying on the dcache. 10291da177e4SLinus Torvalds */ 1030fc9b52cdSHarvey Harrison static int link_path_walk(const char *name, struct nameidata *nd) 10311da177e4SLinus Torvalds { 10321da177e4SLinus Torvalds struct nameidata save = *nd; 10331da177e4SLinus Torvalds int result; 10341da177e4SLinus Torvalds 10351da177e4SLinus Torvalds /* make sure the stuff we saved doesn't go away */ 10364ac91378SJan Blunck dget(save.path.dentry); 10374ac91378SJan Blunck mntget(save.path.mnt); 10381da177e4SLinus Torvalds 10391da177e4SLinus Torvalds result = __link_path_walk(name, nd); 10401da177e4SLinus Torvalds if (result == -ESTALE) { 10411da177e4SLinus Torvalds *nd = save; 10424ac91378SJan Blunck dget(nd->path.dentry); 10434ac91378SJan Blunck mntget(nd->path.mnt); 10441da177e4SLinus Torvalds nd->flags |= LOOKUP_REVAL; 10451da177e4SLinus Torvalds result = __link_path_walk(name, nd); 10461da177e4SLinus Torvalds } 10471da177e4SLinus Torvalds 104809da5916SJan Blunck path_put(&save.path); 10491da177e4SLinus Torvalds 10501da177e4SLinus Torvalds return result; 10511da177e4SLinus Torvalds } 10521da177e4SLinus Torvalds 1053fc9b52cdSHarvey Harrison static int path_walk(const char *name, struct nameidata *nd) 10541da177e4SLinus Torvalds { 10551da177e4SLinus Torvalds current->total_link_count = 0; 10561da177e4SLinus Torvalds return link_path_walk(name, nd); 10571da177e4SLinus Torvalds } 10581da177e4SLinus Torvalds 1059ea3834d9SPrasanna Meda /* 1060ea3834d9SPrasanna Meda * SMP-safe: Returns 1 and nd will have valid dentry and mnt, if 1061ea3834d9SPrasanna Meda * everything is done. Returns 0 and drops input nd, if lookup failed; 1062ea3834d9SPrasanna Meda */ 10631da177e4SLinus Torvalds static int __emul_lookup_dentry(const char *name, struct nameidata *nd) 10641da177e4SLinus Torvalds { 10651da177e4SLinus Torvalds if (path_walk(name, nd)) 10661da177e4SLinus Torvalds return 0; /* something went wrong... */ 10671da177e4SLinus Torvalds 10684ac91378SJan Blunck if (!nd->path.dentry->d_inode || 10694ac91378SJan Blunck S_ISDIR(nd->path.dentry->d_inode->i_mode)) { 107009da5916SJan Blunck struct path old_path = nd->path; 10711da177e4SLinus Torvalds struct qstr last = nd->last; 10721da177e4SLinus Torvalds int last_type = nd->last_type; 1073e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 1074e518ddb7SAndreas Mohr 10751da177e4SLinus Torvalds /* 1076e518ddb7SAndreas Mohr * NAME was not found in alternate root or it's a directory. 1077e518ddb7SAndreas Mohr * Try to find it in the normal root: 10781da177e4SLinus Torvalds */ 10791da177e4SLinus Torvalds nd->last_type = LAST_ROOT; 1080e518ddb7SAndreas Mohr read_lock(&fs->lock); 10816ac08c39SJan Blunck nd->path = fs->root; 10826ac08c39SJan Blunck path_get(&fs->root); 1083e518ddb7SAndreas Mohr read_unlock(&fs->lock); 10841da177e4SLinus Torvalds if (path_walk(name, nd) == 0) { 10854ac91378SJan Blunck if (nd->path.dentry->d_inode) { 108609da5916SJan Blunck path_put(&old_path); 10871da177e4SLinus Torvalds return 1; 10881da177e4SLinus Torvalds } 10891d957f9bSJan Blunck path_put(&nd->path); 10901da177e4SLinus Torvalds } 109109da5916SJan Blunck nd->path = old_path; 10921da177e4SLinus Torvalds nd->last = last; 10931da177e4SLinus Torvalds nd->last_type = last_type; 10941da177e4SLinus Torvalds } 10951da177e4SLinus Torvalds return 1; 10961da177e4SLinus Torvalds } 10971da177e4SLinus Torvalds 10981da177e4SLinus Torvalds void set_fs_altroot(void) 10991da177e4SLinus Torvalds { 11001da177e4SLinus Torvalds char *emul = __emul_prefix(); 11011da177e4SLinus Torvalds struct nameidata nd; 11026ac08c39SJan Blunck struct path path = {}, old_path; 11031da177e4SLinus Torvalds int err; 1104e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 11051da177e4SLinus Torvalds 11061da177e4SLinus Torvalds if (!emul) 11071da177e4SLinus Torvalds goto set_it; 11081da177e4SLinus Torvalds err = path_lookup(emul, LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_NOALT, &nd); 11096ac08c39SJan Blunck if (!err) 11106ac08c39SJan Blunck path = nd.path; 11111da177e4SLinus Torvalds set_it: 1112e518ddb7SAndreas Mohr write_lock(&fs->lock); 11136ac08c39SJan Blunck old_path = fs->altroot; 11146ac08c39SJan Blunck fs->altroot = path; 1115e518ddb7SAndreas Mohr write_unlock(&fs->lock); 11166ac08c39SJan Blunck if (old_path.dentry) 11176ac08c39SJan Blunck path_put(&old_path); 11181da177e4SLinus Torvalds } 11191da177e4SLinus Torvalds 1120ea3834d9SPrasanna Meda /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1121fc9b52cdSHarvey Harrison static int do_path_lookup(int dfd, const char *name, 11225590ff0dSUlrich Drepper unsigned int flags, struct nameidata *nd) 11231da177e4SLinus Torvalds { 1124ea3834d9SPrasanna Meda int retval = 0; 1125170aa3d0SUlrich Drepper int fput_needed; 1126170aa3d0SUlrich Drepper struct file *file; 1127e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 11281da177e4SLinus Torvalds 11291da177e4SLinus Torvalds nd->last_type = LAST_ROOT; /* if there are only slashes... */ 11301da177e4SLinus Torvalds nd->flags = flags; 11311da177e4SLinus Torvalds nd->depth = 0; 11321da177e4SLinus Torvalds 11331da177e4SLinus Torvalds if (*name=='/') { 1134e518ddb7SAndreas Mohr read_lock(&fs->lock); 11356ac08c39SJan Blunck if (fs->altroot.dentry && !(nd->flags & LOOKUP_NOALT)) { 11366ac08c39SJan Blunck nd->path = fs->altroot; 11376ac08c39SJan Blunck path_get(&fs->altroot); 1138e518ddb7SAndreas Mohr read_unlock(&fs->lock); 11391da177e4SLinus Torvalds if (__emul_lookup_dentry(name,nd)) 1140ea3834d9SPrasanna Meda goto out; /* found in altroot */ 1141e518ddb7SAndreas Mohr read_lock(&fs->lock); 11421da177e4SLinus Torvalds } 11436ac08c39SJan Blunck nd->path = fs->root; 11446ac08c39SJan Blunck path_get(&fs->root); 1145e518ddb7SAndreas Mohr read_unlock(&fs->lock); 11465590ff0dSUlrich Drepper } else if (dfd == AT_FDCWD) { 1147e518ddb7SAndreas Mohr read_lock(&fs->lock); 11486ac08c39SJan Blunck nd->path = fs->pwd; 11496ac08c39SJan Blunck path_get(&fs->pwd); 1150e518ddb7SAndreas Mohr read_unlock(&fs->lock); 11515590ff0dSUlrich Drepper } else { 11525590ff0dSUlrich Drepper struct dentry *dentry; 11535590ff0dSUlrich Drepper 11545590ff0dSUlrich Drepper file = fget_light(dfd, &fput_needed); 11555590ff0dSUlrich Drepper retval = -EBADF; 1156170aa3d0SUlrich Drepper if (!file) 11576d09bb62STrond Myklebust goto out_fail; 11585590ff0dSUlrich Drepper 11590f7fc9e4SJosef "Jeff" Sipek dentry = file->f_path.dentry; 11605590ff0dSUlrich Drepper 11615590ff0dSUlrich Drepper retval = -ENOTDIR; 1162170aa3d0SUlrich Drepper if (!S_ISDIR(dentry->d_inode->i_mode)) 11636d09bb62STrond Myklebust goto fput_fail; 11645590ff0dSUlrich Drepper 11655590ff0dSUlrich Drepper retval = file_permission(file, MAY_EXEC); 1166170aa3d0SUlrich Drepper if (retval) 11676d09bb62STrond Myklebust goto fput_fail; 11685590ff0dSUlrich Drepper 11695dd784d0SJan Blunck nd->path = file->f_path; 11705dd784d0SJan Blunck path_get(&file->f_path); 11715590ff0dSUlrich Drepper 11725590ff0dSUlrich Drepper fput_light(file, fput_needed); 11731da177e4SLinus Torvalds } 11742dfdd266SJosef 'Jeff' Sipek 11752dfdd266SJosef 'Jeff' Sipek retval = path_walk(name, nd); 1176ea3834d9SPrasanna Meda out: 11774ac91378SJan Blunck if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && 11784ac91378SJan Blunck nd->path.dentry->d_inode)) 11794ac91378SJan Blunck audit_inode(name, nd->path.dentry); 11806d09bb62STrond Myklebust out_fail: 1181170aa3d0SUlrich Drepper return retval; 1182170aa3d0SUlrich Drepper 11836d09bb62STrond Myklebust fput_fail: 1184170aa3d0SUlrich Drepper fput_light(file, fput_needed); 11856d09bb62STrond Myklebust goto out_fail; 11861da177e4SLinus Torvalds } 11871da177e4SLinus Torvalds 1188fc9b52cdSHarvey Harrison int path_lookup(const char *name, unsigned int flags, 11895590ff0dSUlrich Drepper struct nameidata *nd) 11905590ff0dSUlrich Drepper { 11915590ff0dSUlrich Drepper return do_path_lookup(AT_FDCWD, name, flags, nd); 11925590ff0dSUlrich Drepper } 11935590ff0dSUlrich Drepper 119416f18200SJosef 'Jeff' Sipek /** 119516f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 119616f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 119716f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 119816f18200SJosef 'Jeff' Sipek * @name: pointer to file name 119916f18200SJosef 'Jeff' Sipek * @flags: lookup flags 120016f18200SJosef 'Jeff' Sipek * @nd: pointer to nameidata 120116f18200SJosef 'Jeff' Sipek */ 120216f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 120316f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 120416f18200SJosef 'Jeff' Sipek struct nameidata *nd) 120516f18200SJosef 'Jeff' Sipek { 120616f18200SJosef 'Jeff' Sipek int retval; 120716f18200SJosef 'Jeff' Sipek 120816f18200SJosef 'Jeff' Sipek /* same as do_path_lookup */ 120916f18200SJosef 'Jeff' Sipek nd->last_type = LAST_ROOT; 121016f18200SJosef 'Jeff' Sipek nd->flags = flags; 121116f18200SJosef 'Jeff' Sipek nd->depth = 0; 121216f18200SJosef 'Jeff' Sipek 12134ac91378SJan Blunck nd->path.mnt = mntget(mnt); 12144ac91378SJan Blunck nd->path.dentry = dget(dentry); 121516f18200SJosef 'Jeff' Sipek 121616f18200SJosef 'Jeff' Sipek retval = path_walk(name, nd); 12174ac91378SJan Blunck if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && 12184ac91378SJan Blunck nd->path.dentry->d_inode)) 12194ac91378SJan Blunck audit_inode(name, nd->path.dentry); 122016f18200SJosef 'Jeff' Sipek 122116f18200SJosef 'Jeff' Sipek return retval; 122216f18200SJosef 'Jeff' Sipek 122316f18200SJosef 'Jeff' Sipek } 122416f18200SJosef 'Jeff' Sipek 12255590ff0dSUlrich Drepper static int __path_lookup_intent_open(int dfd, const char *name, 12265590ff0dSUlrich Drepper unsigned int lookup_flags, struct nameidata *nd, 12275590ff0dSUlrich Drepper int open_flags, int create_mode) 1228834f2a4aSTrond Myklebust { 1229834f2a4aSTrond Myklebust struct file *filp = get_empty_filp(); 1230834f2a4aSTrond Myklebust int err; 1231834f2a4aSTrond Myklebust 1232834f2a4aSTrond Myklebust if (filp == NULL) 1233834f2a4aSTrond Myklebust return -ENFILE; 1234834f2a4aSTrond Myklebust nd->intent.open.file = filp; 1235834f2a4aSTrond Myklebust nd->intent.open.flags = open_flags; 1236834f2a4aSTrond Myklebust nd->intent.open.create_mode = create_mode; 12375590ff0dSUlrich Drepper err = do_path_lookup(dfd, name, lookup_flags|LOOKUP_OPEN, nd); 1238834f2a4aSTrond Myklebust if (IS_ERR(nd->intent.open.file)) { 1239834f2a4aSTrond Myklebust if (err == 0) { 1240834f2a4aSTrond Myklebust err = PTR_ERR(nd->intent.open.file); 12411d957f9bSJan Blunck path_put(&nd->path); 1242834f2a4aSTrond Myklebust } 1243834f2a4aSTrond Myklebust } else if (err != 0) 1244834f2a4aSTrond Myklebust release_open_intent(nd); 1245834f2a4aSTrond Myklebust return err; 1246834f2a4aSTrond Myklebust } 1247834f2a4aSTrond Myklebust 1248834f2a4aSTrond Myklebust /** 1249834f2a4aSTrond Myklebust * path_lookup_open - lookup a file path with open intent 12507045f37bSMartin Waitz * @dfd: the directory to use as base, or AT_FDCWD 1251834f2a4aSTrond Myklebust * @name: pointer to file name 1252834f2a4aSTrond Myklebust * @lookup_flags: lookup intent flags 1253834f2a4aSTrond Myklebust * @nd: pointer to nameidata 1254834f2a4aSTrond Myklebust * @open_flags: open intent flags 1255834f2a4aSTrond Myklebust */ 12565590ff0dSUlrich Drepper int path_lookup_open(int dfd, const char *name, unsigned int lookup_flags, 1257834f2a4aSTrond Myklebust struct nameidata *nd, int open_flags) 1258834f2a4aSTrond Myklebust { 12595590ff0dSUlrich Drepper return __path_lookup_intent_open(dfd, name, lookup_flags, nd, 1260834f2a4aSTrond Myklebust open_flags, 0); 1261834f2a4aSTrond Myklebust } 1262834f2a4aSTrond Myklebust 1263834f2a4aSTrond Myklebust /** 1264834f2a4aSTrond Myklebust * path_lookup_create - lookup a file path with open + create intent 12657045f37bSMartin Waitz * @dfd: the directory to use as base, or AT_FDCWD 1266834f2a4aSTrond Myklebust * @name: pointer to file name 1267834f2a4aSTrond Myklebust * @lookup_flags: lookup intent flags 1268834f2a4aSTrond Myklebust * @nd: pointer to nameidata 1269834f2a4aSTrond Myklebust * @open_flags: open intent flags 1270834f2a4aSTrond Myklebust * @create_mode: create intent flags 1271834f2a4aSTrond Myklebust */ 12725590ff0dSUlrich Drepper static int path_lookup_create(int dfd, const char *name, 12735590ff0dSUlrich Drepper unsigned int lookup_flags, struct nameidata *nd, 12745590ff0dSUlrich Drepper int open_flags, int create_mode) 1275834f2a4aSTrond Myklebust { 12765590ff0dSUlrich Drepper return __path_lookup_intent_open(dfd, name, lookup_flags|LOOKUP_CREATE, 12775590ff0dSUlrich Drepper nd, open_flags, create_mode); 1278834f2a4aSTrond Myklebust } 1279834f2a4aSTrond Myklebust 1280834f2a4aSTrond Myklebust int __user_path_lookup_open(const char __user *name, unsigned int lookup_flags, 1281834f2a4aSTrond Myklebust struct nameidata *nd, int open_flags) 1282834f2a4aSTrond Myklebust { 1283834f2a4aSTrond Myklebust char *tmp = getname(name); 1284834f2a4aSTrond Myklebust int err = PTR_ERR(tmp); 1285834f2a4aSTrond Myklebust 1286834f2a4aSTrond Myklebust if (!IS_ERR(tmp)) { 12875590ff0dSUlrich Drepper err = __path_lookup_intent_open(AT_FDCWD, tmp, lookup_flags, nd, open_flags, 0); 1288834f2a4aSTrond Myklebust putname(tmp); 1289834f2a4aSTrond Myklebust } 1290834f2a4aSTrond Myklebust return err; 1291834f2a4aSTrond Myklebust } 1292834f2a4aSTrond Myklebust 1293eead1911SChristoph Hellwig static struct dentry *__lookup_hash(struct qstr *name, 1294eead1911SChristoph Hellwig struct dentry *base, struct nameidata *nd) 12951da177e4SLinus Torvalds { 12961da177e4SLinus Torvalds struct dentry *dentry; 12971da177e4SLinus Torvalds struct inode *inode; 12981da177e4SLinus Torvalds int err; 12991da177e4SLinus Torvalds 13001da177e4SLinus Torvalds inode = base->d_inode; 13011da177e4SLinus Torvalds 13021da177e4SLinus Torvalds /* 13031da177e4SLinus Torvalds * See if the low-level filesystem might want 13041da177e4SLinus Torvalds * to use its own hash.. 13051da177e4SLinus Torvalds */ 13061da177e4SLinus Torvalds if (base->d_op && base->d_op->d_hash) { 13071da177e4SLinus Torvalds err = base->d_op->d_hash(base, name); 13081da177e4SLinus Torvalds dentry = ERR_PTR(err); 13091da177e4SLinus Torvalds if (err < 0) 13101da177e4SLinus Torvalds goto out; 13111da177e4SLinus Torvalds } 13121da177e4SLinus Torvalds 13131da177e4SLinus Torvalds dentry = cached_lookup(base, name, nd); 13141da177e4SLinus Torvalds if (!dentry) { 13151da177e4SLinus Torvalds struct dentry *new = d_alloc(base, name); 13161da177e4SLinus Torvalds dentry = ERR_PTR(-ENOMEM); 13171da177e4SLinus Torvalds if (!new) 13181da177e4SLinus Torvalds goto out; 13191da177e4SLinus Torvalds dentry = inode->i_op->lookup(inode, new, nd); 13201da177e4SLinus Torvalds if (!dentry) 13211da177e4SLinus Torvalds dentry = new; 13221da177e4SLinus Torvalds else 13231da177e4SLinus Torvalds dput(new); 13241da177e4SLinus Torvalds } 13251da177e4SLinus Torvalds out: 13261da177e4SLinus Torvalds return dentry; 13271da177e4SLinus Torvalds } 13281da177e4SLinus Torvalds 1329057f6c01SJames Morris /* 1330057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1331057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1332057f6c01SJames Morris * SMP-safe. 1333057f6c01SJames Morris */ 1334a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 13351da177e4SLinus Torvalds { 1336eead1911SChristoph Hellwig int err; 1337eead1911SChristoph Hellwig 13384ac91378SJan Blunck err = permission(nd->path.dentry->d_inode, MAY_EXEC, nd); 1339eead1911SChristoph Hellwig if (err) 1340eead1911SChristoph Hellwig return ERR_PTR(err); 13414ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 13421da177e4SLinus Torvalds } 13431da177e4SLinus Torvalds 1344eead1911SChristoph Hellwig static int __lookup_one_len(const char *name, struct qstr *this, 1345eead1911SChristoph Hellwig struct dentry *base, int len) 13461da177e4SLinus Torvalds { 13471da177e4SLinus Torvalds unsigned long hash; 13481da177e4SLinus Torvalds unsigned int c; 13491da177e4SLinus Torvalds 1350057f6c01SJames Morris this->name = name; 1351057f6c01SJames Morris this->len = len; 13521da177e4SLinus Torvalds if (!len) 1353057f6c01SJames Morris return -EACCES; 13541da177e4SLinus Torvalds 13551da177e4SLinus Torvalds hash = init_name_hash(); 13561da177e4SLinus Torvalds while (len--) { 13571da177e4SLinus Torvalds c = *(const unsigned char *)name++; 13581da177e4SLinus Torvalds if (c == '/' || c == '\0') 1359057f6c01SJames Morris return -EACCES; 13601da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 13611da177e4SLinus Torvalds } 1362057f6c01SJames Morris this->hash = end_name_hash(hash); 1363057f6c01SJames Morris return 0; 1364057f6c01SJames Morris } 13651da177e4SLinus Torvalds 1366eead1911SChristoph Hellwig /** 1367a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1368eead1911SChristoph Hellwig * @name: pathname component to lookup 1369eead1911SChristoph Hellwig * @base: base directory to lookup from 1370eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1371eead1911SChristoph Hellwig * 1372a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1373a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1374eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1375eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1376eead1911SChristoph Hellwig */ 1377057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1378057f6c01SJames Morris { 1379057f6c01SJames Morris int err; 1380057f6c01SJames Morris struct qstr this; 1381057f6c01SJames Morris 1382057f6c01SJames Morris err = __lookup_one_len(name, &this, base, len); 1383057f6c01SJames Morris if (err) 1384057f6c01SJames Morris return ERR_PTR(err); 1385eead1911SChristoph Hellwig 1386eead1911SChristoph Hellwig err = permission(base->d_inode, MAY_EXEC, NULL); 1387eead1911SChristoph Hellwig if (err) 1388eead1911SChristoph Hellwig return ERR_PTR(err); 138949705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1390057f6c01SJames Morris } 1391057f6c01SJames Morris 1392eead1911SChristoph Hellwig /** 1393eead1911SChristoph Hellwig * lookup_one_noperm - bad hack for sysfs 1394eead1911SChristoph Hellwig * @name: pathname component to lookup 1395eead1911SChristoph Hellwig * @base: base directory to lookup from 1396eead1911SChristoph Hellwig * 1397eead1911SChristoph Hellwig * This is a variant of lookup_one_len that doesn't perform any permission 1398eead1911SChristoph Hellwig * checks. It's a horrible hack to work around the braindead sysfs 1399eead1911SChristoph Hellwig * architecture and should not be used anywhere else. 1400eead1911SChristoph Hellwig * 1401eead1911SChristoph Hellwig * DON'T USE THIS FUNCTION EVER, thanks. 1402eead1911SChristoph Hellwig */ 1403eead1911SChristoph Hellwig struct dentry *lookup_one_noperm(const char *name, struct dentry *base) 1404057f6c01SJames Morris { 1405057f6c01SJames Morris int err; 1406057f6c01SJames Morris struct qstr this; 1407057f6c01SJames Morris 1408eead1911SChristoph Hellwig err = __lookup_one_len(name, &this, base, strlen(name)); 1409057f6c01SJames Morris if (err) 1410057f6c01SJames Morris return ERR_PTR(err); 1411eead1911SChristoph Hellwig return __lookup_hash(&this, base, NULL); 14121da177e4SLinus Torvalds } 14131da177e4SLinus Torvalds 1414fc9b52cdSHarvey Harrison int __user_walk_fd(int dfd, const char __user *name, unsigned flags, 14155590ff0dSUlrich Drepper struct nameidata *nd) 14161da177e4SLinus Torvalds { 14171da177e4SLinus Torvalds char *tmp = getname(name); 14181da177e4SLinus Torvalds int err = PTR_ERR(tmp); 14191da177e4SLinus Torvalds 14201da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 14215590ff0dSUlrich Drepper err = do_path_lookup(dfd, tmp, flags, nd); 14221da177e4SLinus Torvalds putname(tmp); 14231da177e4SLinus Torvalds } 14241da177e4SLinus Torvalds return err; 14251da177e4SLinus Torvalds } 14261da177e4SLinus Torvalds 1427fc9b52cdSHarvey Harrison int __user_walk(const char __user *name, unsigned flags, struct nameidata *nd) 14285590ff0dSUlrich Drepper { 14295590ff0dSUlrich Drepper return __user_walk_fd(AT_FDCWD, name, flags, nd); 14305590ff0dSUlrich Drepper } 14315590ff0dSUlrich Drepper 14321da177e4SLinus Torvalds /* 14331da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 14341da177e4SLinus Torvalds * minimal. 14351da177e4SLinus Torvalds */ 14361da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 14371da177e4SLinus Torvalds { 14381da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 14391da177e4SLinus Torvalds return 0; 14401da177e4SLinus Torvalds if (inode->i_uid == current->fsuid) 14411da177e4SLinus Torvalds return 0; 14421da177e4SLinus Torvalds if (dir->i_uid == current->fsuid) 14431da177e4SLinus Torvalds return 0; 14441da177e4SLinus Torvalds return !capable(CAP_FOWNER); 14451da177e4SLinus Torvalds } 14461da177e4SLinus Torvalds 14471da177e4SLinus Torvalds /* 14481da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 14491da177e4SLinus Torvalds * whether the type of victim is right. 14501da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 14511da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 14521da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 14531da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 14541da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 14551da177e4SLinus Torvalds * a. be owner of dir, or 14561da177e4SLinus Torvalds * b. be owner of victim, or 14571da177e4SLinus Torvalds * c. have CAP_FOWNER capability 14581da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 14591da177e4SLinus Torvalds * links pointing to it. 14601da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 14611da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 14621da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 14631da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 14641da177e4SLinus Torvalds * nfs_async_unlink(). 14651da177e4SLinus Torvalds */ 1466858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 14671da177e4SLinus Torvalds { 14681da177e4SLinus Torvalds int error; 14691da177e4SLinus Torvalds 14701da177e4SLinus Torvalds if (!victim->d_inode) 14711da177e4SLinus Torvalds return -ENOENT; 14721da177e4SLinus Torvalds 14731da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 14745a190ae6SAl Viro audit_inode_child(victim->d_name.name, victim, dir); 14751da177e4SLinus Torvalds 14761da177e4SLinus Torvalds error = permission(dir,MAY_WRITE | MAY_EXEC, NULL); 14771da177e4SLinus Torvalds if (error) 14781da177e4SLinus Torvalds return error; 14791da177e4SLinus Torvalds if (IS_APPEND(dir)) 14801da177e4SLinus Torvalds return -EPERM; 14811da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 14821da177e4SLinus Torvalds IS_IMMUTABLE(victim->d_inode)) 14831da177e4SLinus Torvalds return -EPERM; 14841da177e4SLinus Torvalds if (isdir) { 14851da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 14861da177e4SLinus Torvalds return -ENOTDIR; 14871da177e4SLinus Torvalds if (IS_ROOT(victim)) 14881da177e4SLinus Torvalds return -EBUSY; 14891da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 14901da177e4SLinus Torvalds return -EISDIR; 14911da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 14921da177e4SLinus Torvalds return -ENOENT; 14931da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 14941da177e4SLinus Torvalds return -EBUSY; 14951da177e4SLinus Torvalds return 0; 14961da177e4SLinus Torvalds } 14971da177e4SLinus Torvalds 14981da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 14991da177e4SLinus Torvalds * dir. 15001da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 15011da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 15021da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 15031da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 15041da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 15051da177e4SLinus Torvalds */ 15061da177e4SLinus Torvalds static inline int may_create(struct inode *dir, struct dentry *child, 15071da177e4SLinus Torvalds struct nameidata *nd) 15081da177e4SLinus Torvalds { 15091da177e4SLinus Torvalds if (child->d_inode) 15101da177e4SLinus Torvalds return -EEXIST; 15111da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 15121da177e4SLinus Torvalds return -ENOENT; 15131da177e4SLinus Torvalds return permission(dir,MAY_WRITE | MAY_EXEC, nd); 15141da177e4SLinus Torvalds } 15151da177e4SLinus Torvalds 15161da177e4SLinus Torvalds /* 15171da177e4SLinus Torvalds * O_DIRECTORY translates into forcing a directory lookup. 15181da177e4SLinus Torvalds */ 15191da177e4SLinus Torvalds static inline int lookup_flags(unsigned int f) 15201da177e4SLinus Torvalds { 15211da177e4SLinus Torvalds unsigned long retval = LOOKUP_FOLLOW; 15221da177e4SLinus Torvalds 15231da177e4SLinus Torvalds if (f & O_NOFOLLOW) 15241da177e4SLinus Torvalds retval &= ~LOOKUP_FOLLOW; 15251da177e4SLinus Torvalds 15261da177e4SLinus Torvalds if (f & O_DIRECTORY) 15271da177e4SLinus Torvalds retval |= LOOKUP_DIRECTORY; 15281da177e4SLinus Torvalds 15291da177e4SLinus Torvalds return retval; 15301da177e4SLinus Torvalds } 15311da177e4SLinus Torvalds 15321da177e4SLinus Torvalds /* 15331da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 15341da177e4SLinus Torvalds */ 15351da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 15361da177e4SLinus Torvalds { 15371da177e4SLinus Torvalds struct dentry *p; 15381da177e4SLinus Torvalds 15391da177e4SLinus Torvalds if (p1 == p2) { 1540f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 15411da177e4SLinus Torvalds return NULL; 15421da177e4SLinus Torvalds } 15431da177e4SLinus Torvalds 1544a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 15451da177e4SLinus Torvalds 15461da177e4SLinus Torvalds for (p = p1; p->d_parent != p; p = p->d_parent) { 15471da177e4SLinus Torvalds if (p->d_parent == p2) { 1548f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 1549f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 15501da177e4SLinus Torvalds return p; 15511da177e4SLinus Torvalds } 15521da177e4SLinus Torvalds } 15531da177e4SLinus Torvalds 15541da177e4SLinus Torvalds for (p = p2; p->d_parent != p; p = p->d_parent) { 15551da177e4SLinus Torvalds if (p->d_parent == p1) { 1556f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1557f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 15581da177e4SLinus Torvalds return p; 15591da177e4SLinus Torvalds } 15601da177e4SLinus Torvalds } 15611da177e4SLinus Torvalds 1562f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1563f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 15641da177e4SLinus Torvalds return NULL; 15651da177e4SLinus Torvalds } 15661da177e4SLinus Torvalds 15671da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 15681da177e4SLinus Torvalds { 15691b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 15701da177e4SLinus Torvalds if (p1 != p2) { 15711b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 1572a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 15731da177e4SLinus Torvalds } 15741da177e4SLinus Torvalds } 15751da177e4SLinus Torvalds 15761da177e4SLinus Torvalds int vfs_create(struct inode *dir, struct dentry *dentry, int mode, 15771da177e4SLinus Torvalds struct nameidata *nd) 15781da177e4SLinus Torvalds { 15791da177e4SLinus Torvalds int error = may_create(dir, dentry, nd); 15801da177e4SLinus Torvalds 15811da177e4SLinus Torvalds if (error) 15821da177e4SLinus Torvalds return error; 15831da177e4SLinus Torvalds 15841da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->create) 15851da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 15861da177e4SLinus Torvalds mode &= S_IALLUGO; 15871da177e4SLinus Torvalds mode |= S_IFREG; 15881da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 15891da177e4SLinus Torvalds if (error) 15901da177e4SLinus Torvalds return error; 15911da177e4SLinus Torvalds DQUOT_INIT(dir); 15921da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 1593a74574aaSStephen Smalley if (!error) 1594f38aa942SAmy Griffis fsnotify_create(dir, dentry); 15951da177e4SLinus Torvalds return error; 15961da177e4SLinus Torvalds } 15971da177e4SLinus Torvalds 15981da177e4SLinus Torvalds int may_open(struct nameidata *nd, int acc_mode, int flag) 15991da177e4SLinus Torvalds { 16004ac91378SJan Blunck struct dentry *dentry = nd->path.dentry; 16011da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 16021da177e4SLinus Torvalds int error; 16031da177e4SLinus Torvalds 16041da177e4SLinus Torvalds if (!inode) 16051da177e4SLinus Torvalds return -ENOENT; 16061da177e4SLinus Torvalds 16071da177e4SLinus Torvalds if (S_ISLNK(inode->i_mode)) 16081da177e4SLinus Torvalds return -ELOOP; 16091da177e4SLinus Torvalds 1610974a9f0bSLinus Torvalds if (S_ISDIR(inode->i_mode) && (acc_mode & MAY_WRITE)) 16111da177e4SLinus Torvalds return -EISDIR; 16121da177e4SLinus Torvalds 16131da177e4SLinus Torvalds /* 16141da177e4SLinus Torvalds * FIFO's, sockets and device files are special: they don't 16151da177e4SLinus Torvalds * actually live on the filesystem itself, and as such you 16161da177e4SLinus Torvalds * can write to them even if the filesystem is read-only. 16171da177e4SLinus Torvalds */ 16181da177e4SLinus Torvalds if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) { 16191da177e4SLinus Torvalds flag &= ~O_TRUNC; 16201da177e4SLinus Torvalds } else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) { 16214ac91378SJan Blunck if (nd->path.mnt->mnt_flags & MNT_NODEV) 16221da177e4SLinus Torvalds return -EACCES; 16231da177e4SLinus Torvalds 16241da177e4SLinus Torvalds flag &= ~O_TRUNC; 1625974a9f0bSLinus Torvalds } else if (IS_RDONLY(inode) && (acc_mode & MAY_WRITE)) 16261da177e4SLinus Torvalds return -EROFS; 1627b41572e9SDave Hansen 1628b41572e9SDave Hansen error = vfs_permission(nd, acc_mode); 1629b41572e9SDave Hansen if (error) 1630b41572e9SDave Hansen return error; 16311da177e4SLinus Torvalds /* 16321da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 16331da177e4SLinus Torvalds */ 16341da177e4SLinus Torvalds if (IS_APPEND(inode)) { 16351da177e4SLinus Torvalds if ((flag & FMODE_WRITE) && !(flag & O_APPEND)) 16361da177e4SLinus Torvalds return -EPERM; 16371da177e4SLinus Torvalds if (flag & O_TRUNC) 16381da177e4SLinus Torvalds return -EPERM; 16391da177e4SLinus Torvalds } 16401da177e4SLinus Torvalds 16411da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 16421da177e4SLinus Torvalds if (flag & O_NOATIME) 16433bd858abSSatyam Sharma if (!is_owner_or_cap(inode)) 16441da177e4SLinus Torvalds return -EPERM; 16451da177e4SLinus Torvalds 16461da177e4SLinus Torvalds /* 16471da177e4SLinus Torvalds * Ensure there are no outstanding leases on the file. 16481da177e4SLinus Torvalds */ 16491da177e4SLinus Torvalds error = break_lease(inode, flag); 16501da177e4SLinus Torvalds if (error) 16511da177e4SLinus Torvalds return error; 16521da177e4SLinus Torvalds 16531da177e4SLinus Torvalds if (flag & O_TRUNC) { 16541da177e4SLinus Torvalds error = get_write_access(inode); 16551da177e4SLinus Torvalds if (error) 16561da177e4SLinus Torvalds return error; 16571da177e4SLinus Torvalds 16581da177e4SLinus Torvalds /* 16591da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 16601da177e4SLinus Torvalds */ 16611da177e4SLinus Torvalds error = locks_verify_locked(inode); 16621da177e4SLinus Torvalds if (!error) { 16631da177e4SLinus Torvalds DQUOT_INIT(inode); 16641da177e4SLinus Torvalds 1665d139d7ffSMiklos Szeredi error = do_truncate(dentry, 0, 1666d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 1667d139d7ffSMiklos Szeredi NULL); 16681da177e4SLinus Torvalds } 16691da177e4SLinus Torvalds put_write_access(inode); 16701da177e4SLinus Torvalds if (error) 16711da177e4SLinus Torvalds return error; 16721da177e4SLinus Torvalds } else 16731da177e4SLinus Torvalds if (flag & FMODE_WRITE) 16741da177e4SLinus Torvalds DQUOT_INIT(inode); 16751da177e4SLinus Torvalds 16761da177e4SLinus Torvalds return 0; 16771da177e4SLinus Torvalds } 16781da177e4SLinus Torvalds 1679aab520e2SDave Hansen static int open_namei_create(struct nameidata *nd, struct path *path, 1680aab520e2SDave Hansen int flag, int mode) 1681aab520e2SDave Hansen { 1682aab520e2SDave Hansen int error; 16834ac91378SJan Blunck struct dentry *dir = nd->path.dentry; 1684aab520e2SDave Hansen 1685aab520e2SDave Hansen if (!IS_POSIXACL(dir->d_inode)) 1686aab520e2SDave Hansen mode &= ~current->fs->umask; 1687aab520e2SDave Hansen error = vfs_create(dir->d_inode, path->dentry, mode, nd); 1688aab520e2SDave Hansen mutex_unlock(&dir->d_inode->i_mutex); 16894ac91378SJan Blunck dput(nd->path.dentry); 16904ac91378SJan Blunck nd->path.dentry = path->dentry; 1691aab520e2SDave Hansen if (error) 1692aab520e2SDave Hansen return error; 1693aab520e2SDave Hansen /* Don't check for write permission, don't truncate */ 1694aab520e2SDave Hansen return may_open(nd, 0, flag & ~O_TRUNC); 1695aab520e2SDave Hansen } 1696aab520e2SDave Hansen 16971da177e4SLinus Torvalds /* 16981da177e4SLinus Torvalds * open_namei() 16991da177e4SLinus Torvalds * 17001da177e4SLinus Torvalds * namei for open - this is in fact almost the whole open-routine. 17011da177e4SLinus Torvalds * 17021da177e4SLinus Torvalds * Note that the low bits of "flag" aren't the same as in the open 17031da177e4SLinus Torvalds * system call - they are 00 - no permissions needed 17041da177e4SLinus Torvalds * 01 - read permission needed 17051da177e4SLinus Torvalds * 10 - write permission needed 17061da177e4SLinus Torvalds * 11 - read/write permissions needed 17071da177e4SLinus Torvalds * which is a lot more logical, and also allows the "no perm" needed 17081da177e4SLinus Torvalds * for symlinks (where the permissions are checked later). 17091da177e4SLinus Torvalds * SMP-safe 17101da177e4SLinus Torvalds */ 17115590ff0dSUlrich Drepper int open_namei(int dfd, const char *pathname, int flag, 17125590ff0dSUlrich Drepper int mode, struct nameidata *nd) 17131da177e4SLinus Torvalds { 1714834f2a4aSTrond Myklebust int acc_mode, error; 17154e7506e4SAl Viro struct path path; 17161da177e4SLinus Torvalds struct dentry *dir; 17171da177e4SLinus Torvalds int count = 0; 17181da177e4SLinus Torvalds 17191da177e4SLinus Torvalds acc_mode = ACC_MODE(flag); 17201da177e4SLinus Torvalds 1721834f2a4aSTrond Myklebust /* O_TRUNC implies we need access checks for write permissions */ 1722834f2a4aSTrond Myklebust if (flag & O_TRUNC) 1723834f2a4aSTrond Myklebust acc_mode |= MAY_WRITE; 1724834f2a4aSTrond Myklebust 17251da177e4SLinus Torvalds /* Allow the LSM permission hook to distinguish append 17261da177e4SLinus Torvalds access from general write access. */ 17271da177e4SLinus Torvalds if (flag & O_APPEND) 17281da177e4SLinus Torvalds acc_mode |= MAY_APPEND; 17291da177e4SLinus Torvalds 17301da177e4SLinus Torvalds /* 17311da177e4SLinus Torvalds * The simplest case - just a plain lookup. 17321da177e4SLinus Torvalds */ 17331da177e4SLinus Torvalds if (!(flag & O_CREAT)) { 17345590ff0dSUlrich Drepper error = path_lookup_open(dfd, pathname, lookup_flags(flag), 17355590ff0dSUlrich Drepper nd, flag); 17361da177e4SLinus Torvalds if (error) 17371da177e4SLinus Torvalds return error; 17381da177e4SLinus Torvalds goto ok; 17391da177e4SLinus Torvalds } 17401da177e4SLinus Torvalds 17411da177e4SLinus Torvalds /* 17421da177e4SLinus Torvalds * Create - we need to know the parent. 17431da177e4SLinus Torvalds */ 17445590ff0dSUlrich Drepper error = path_lookup_create(dfd,pathname,LOOKUP_PARENT,nd,flag,mode); 17451da177e4SLinus Torvalds if (error) 17461da177e4SLinus Torvalds return error; 17471da177e4SLinus Torvalds 17481da177e4SLinus Torvalds /* 17491da177e4SLinus Torvalds * We have the parent and last component. First of all, check 17501da177e4SLinus Torvalds * that we are not asked to creat(2) an obvious directory - that 17511da177e4SLinus Torvalds * will not do. 17521da177e4SLinus Torvalds */ 17531da177e4SLinus Torvalds error = -EISDIR; 17541da177e4SLinus Torvalds if (nd->last_type != LAST_NORM || nd->last.name[nd->last.len]) 17551da177e4SLinus Torvalds goto exit; 17561da177e4SLinus Torvalds 17574ac91378SJan Blunck dir = nd->path.dentry; 17581da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 17591b1dcc1bSJes Sorensen mutex_lock(&dir->d_inode->i_mutex); 176049705b77SChristoph Hellwig path.dentry = lookup_hash(nd); 17614ac91378SJan Blunck path.mnt = nd->path.mnt; 17621da177e4SLinus Torvalds 17631da177e4SLinus Torvalds do_last: 17644e7506e4SAl Viro error = PTR_ERR(path.dentry); 17654e7506e4SAl Viro if (IS_ERR(path.dentry)) { 17661b1dcc1bSJes Sorensen mutex_unlock(&dir->d_inode->i_mutex); 17671da177e4SLinus Torvalds goto exit; 17681da177e4SLinus Torvalds } 17691da177e4SLinus Torvalds 17704af4c52fSOleg Drokin if (IS_ERR(nd->intent.open.file)) { 17714af4c52fSOleg Drokin mutex_unlock(&dir->d_inode->i_mutex); 17724af4c52fSOleg Drokin error = PTR_ERR(nd->intent.open.file); 17734af4c52fSOleg Drokin goto exit_dput; 17744af4c52fSOleg Drokin } 17754af4c52fSOleg Drokin 17761da177e4SLinus Torvalds /* Negative dentry, just create the file */ 17774e7506e4SAl Viro if (!path.dentry->d_inode) { 1778aab520e2SDave Hansen error = open_namei_create(nd, &path, flag, mode); 17791da177e4SLinus Torvalds if (error) 17801da177e4SLinus Torvalds goto exit; 1781aab520e2SDave Hansen return 0; 17821da177e4SLinus Torvalds } 17831da177e4SLinus Torvalds 17841da177e4SLinus Torvalds /* 17851da177e4SLinus Torvalds * It already exists. 17861da177e4SLinus Torvalds */ 17871b1dcc1bSJes Sorensen mutex_unlock(&dir->d_inode->i_mutex); 17885a190ae6SAl Viro audit_inode(pathname, path.dentry); 17891da177e4SLinus Torvalds 17901da177e4SLinus Torvalds error = -EEXIST; 17911da177e4SLinus Torvalds if (flag & O_EXCL) 17921da177e4SLinus Torvalds goto exit_dput; 17931da177e4SLinus Torvalds 1794e13b210fSAl Viro if (__follow_mount(&path)) { 17951da177e4SLinus Torvalds error = -ELOOP; 1796ba7a4c1aSAl Viro if (flag & O_NOFOLLOW) 1797ba7a4c1aSAl Viro goto exit_dput; 17981da177e4SLinus Torvalds } 17993e2efce0SAmy Griffis 18001da177e4SLinus Torvalds error = -ENOENT; 18014e7506e4SAl Viro if (!path.dentry->d_inode) 18021da177e4SLinus Torvalds goto exit_dput; 18034e7506e4SAl Viro if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link) 18041da177e4SLinus Torvalds goto do_link; 18051da177e4SLinus Torvalds 180609dd17d3SMiklos Szeredi path_to_nameidata(&path, nd); 18071da177e4SLinus Torvalds error = -EISDIR; 18084e7506e4SAl Viro if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode)) 18091da177e4SLinus Torvalds goto exit; 18101da177e4SLinus Torvalds ok: 18111da177e4SLinus Torvalds error = may_open(nd, acc_mode, flag); 18121da177e4SLinus Torvalds if (error) 18131da177e4SLinus Torvalds goto exit; 18141da177e4SLinus Torvalds return 0; 18151da177e4SLinus Torvalds 18161da177e4SLinus Torvalds exit_dput: 18171d957f9bSJan Blunck path_put_conditional(&path, nd); 18181da177e4SLinus Torvalds exit: 1819834f2a4aSTrond Myklebust if (!IS_ERR(nd->intent.open.file)) 1820834f2a4aSTrond Myklebust release_open_intent(nd); 18211d957f9bSJan Blunck path_put(&nd->path); 18221da177e4SLinus Torvalds return error; 18231da177e4SLinus Torvalds 18241da177e4SLinus Torvalds do_link: 18251da177e4SLinus Torvalds error = -ELOOP; 18261da177e4SLinus Torvalds if (flag & O_NOFOLLOW) 18271da177e4SLinus Torvalds goto exit_dput; 18281da177e4SLinus Torvalds /* 18291da177e4SLinus Torvalds * This is subtle. Instead of calling do_follow_link() we do the 18301da177e4SLinus Torvalds * thing by hands. The reason is that this way we have zero link_count 18311da177e4SLinus Torvalds * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT. 18321da177e4SLinus Torvalds * After that we have the parent and last component, i.e. 18331da177e4SLinus Torvalds * we are in the same situation as after the first path_walk(). 18341da177e4SLinus Torvalds * Well, almost - if the last component is normal we get its copy 18351da177e4SLinus Torvalds * stored in nd->last.name and we will have to putname() it when we 18361da177e4SLinus Torvalds * are done. Procfs-like symlinks just set LAST_BIND. 18371da177e4SLinus Torvalds */ 18381da177e4SLinus Torvalds nd->flags |= LOOKUP_PARENT; 18394e7506e4SAl Viro error = security_inode_follow_link(path.dentry, nd); 18401da177e4SLinus Torvalds if (error) 18411da177e4SLinus Torvalds goto exit_dput; 1842cd4e91d3SAl Viro error = __do_follow_link(&path, nd); 1843de459215SKirill Korotaev if (error) { 1844de459215SKirill Korotaev /* Does someone understand code flow here? Or it is only 1845de459215SKirill Korotaev * me so stupid? Anathema to whoever designed this non-sense 1846de459215SKirill Korotaev * with "intent.open". 1847de459215SKirill Korotaev */ 1848de459215SKirill Korotaev release_open_intent(nd); 18491da177e4SLinus Torvalds return error; 1850de459215SKirill Korotaev } 18511da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 1852d671d5e5SAl Viro if (nd->last_type == LAST_BIND) 18531da177e4SLinus Torvalds goto ok; 18541da177e4SLinus Torvalds error = -EISDIR; 18551da177e4SLinus Torvalds if (nd->last_type != LAST_NORM) 18561da177e4SLinus Torvalds goto exit; 18571da177e4SLinus Torvalds if (nd->last.name[nd->last.len]) { 185882984114SLinus Torvalds __putname(nd->last.name); 18591da177e4SLinus Torvalds goto exit; 18601da177e4SLinus Torvalds } 18611da177e4SLinus Torvalds error = -ELOOP; 18621da177e4SLinus Torvalds if (count++==32) { 186382984114SLinus Torvalds __putname(nd->last.name); 18641da177e4SLinus Torvalds goto exit; 18651da177e4SLinus Torvalds } 18664ac91378SJan Blunck dir = nd->path.dentry; 18671b1dcc1bSJes Sorensen mutex_lock(&dir->d_inode->i_mutex); 186849705b77SChristoph Hellwig path.dentry = lookup_hash(nd); 18694ac91378SJan Blunck path.mnt = nd->path.mnt; 187082984114SLinus Torvalds __putname(nd->last.name); 18711da177e4SLinus Torvalds goto do_last; 18721da177e4SLinus Torvalds } 18731da177e4SLinus Torvalds 18741da177e4SLinus Torvalds /** 18751da177e4SLinus Torvalds * lookup_create - lookup a dentry, creating it if it doesn't exist 18761da177e4SLinus Torvalds * @nd: nameidata info 18771da177e4SLinus Torvalds * @is_dir: directory flag 18781da177e4SLinus Torvalds * 18791da177e4SLinus Torvalds * Simple function to lookup and return a dentry and create it 18801da177e4SLinus Torvalds * if it doesn't exist. Is SMP-safe. 1881c663e5d8SChristoph Hellwig * 18824ac91378SJan Blunck * Returns with nd->path.dentry->d_inode->i_mutex locked. 18831da177e4SLinus Torvalds */ 18841da177e4SLinus Torvalds struct dentry *lookup_create(struct nameidata *nd, int is_dir) 18851da177e4SLinus Torvalds { 1886c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 18871da177e4SLinus Torvalds 18884ac91378SJan Blunck mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 1889c663e5d8SChristoph Hellwig /* 1890c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 1891c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 1892c663e5d8SChristoph Hellwig */ 18931da177e4SLinus Torvalds if (nd->last_type != LAST_NORM) 18941da177e4SLinus Torvalds goto fail; 18951da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 1896a634904aSASANO Masahiro nd->flags |= LOOKUP_CREATE; 1897a634904aSASANO Masahiro nd->intent.open.flags = O_EXCL; 1898c663e5d8SChristoph Hellwig 1899c663e5d8SChristoph Hellwig /* 1900c663e5d8SChristoph Hellwig * Do the final lookup. 1901c663e5d8SChristoph Hellwig */ 190249705b77SChristoph Hellwig dentry = lookup_hash(nd); 19031da177e4SLinus Torvalds if (IS_ERR(dentry)) 19041da177e4SLinus Torvalds goto fail; 1905c663e5d8SChristoph Hellwig 1906c663e5d8SChristoph Hellwig /* 1907c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 1908c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 1909c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 1910c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 1911c663e5d8SChristoph Hellwig */ 19121da177e4SLinus Torvalds if (!is_dir && nd->last.name[nd->last.len] && !dentry->d_inode) 19131da177e4SLinus Torvalds goto enoent; 19141da177e4SLinus Torvalds return dentry; 19151da177e4SLinus Torvalds enoent: 19161da177e4SLinus Torvalds dput(dentry); 19171da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 19181da177e4SLinus Torvalds fail: 19191da177e4SLinus Torvalds return dentry; 19201da177e4SLinus Torvalds } 1921f81a0bffSChristoph Hellwig EXPORT_SYMBOL_GPL(lookup_create); 19221da177e4SLinus Torvalds 19231da177e4SLinus Torvalds int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 19241da177e4SLinus Torvalds { 19251da177e4SLinus Torvalds int error = may_create(dir, dentry, NULL); 19261da177e4SLinus Torvalds 19271da177e4SLinus Torvalds if (error) 19281da177e4SLinus Torvalds return error; 19291da177e4SLinus Torvalds 19301da177e4SLinus Torvalds if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 19311da177e4SLinus Torvalds return -EPERM; 19321da177e4SLinus Torvalds 19331da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->mknod) 19341da177e4SLinus Torvalds return -EPERM; 19351da177e4SLinus Torvalds 19361da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 19371da177e4SLinus Torvalds if (error) 19381da177e4SLinus Torvalds return error; 19391da177e4SLinus Torvalds 19401da177e4SLinus Torvalds DQUOT_INIT(dir); 19411da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 1942a74574aaSStephen Smalley if (!error) 1943f38aa942SAmy Griffis fsnotify_create(dir, dentry); 19441da177e4SLinus Torvalds return error; 19451da177e4SLinus Torvalds } 19461da177e4SLinus Torvalds 19475590ff0dSUlrich Drepper asmlinkage long sys_mknodat(int dfd, const char __user *filename, int mode, 19485590ff0dSUlrich Drepper unsigned dev) 19491da177e4SLinus Torvalds { 19501da177e4SLinus Torvalds int error = 0; 19511da177e4SLinus Torvalds char * tmp; 19521da177e4SLinus Torvalds struct dentry * dentry; 19531da177e4SLinus Torvalds struct nameidata nd; 19541da177e4SLinus Torvalds 19551da177e4SLinus Torvalds if (S_ISDIR(mode)) 19561da177e4SLinus Torvalds return -EPERM; 19571da177e4SLinus Torvalds tmp = getname(filename); 19581da177e4SLinus Torvalds if (IS_ERR(tmp)) 19591da177e4SLinus Torvalds return PTR_ERR(tmp); 19601da177e4SLinus Torvalds 19615590ff0dSUlrich Drepper error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd); 19621da177e4SLinus Torvalds if (error) 19631da177e4SLinus Torvalds goto out; 19641da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 19651da177e4SLinus Torvalds error = PTR_ERR(dentry); 19661da177e4SLinus Torvalds 19674ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 19681da177e4SLinus Torvalds mode &= ~current->fs->umask; 19691da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 19701da177e4SLinus Torvalds switch (mode & S_IFMT) { 19711da177e4SLinus Torvalds case 0: case S_IFREG: 19724ac91378SJan Blunck error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); 19731da177e4SLinus Torvalds break; 19741da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 19754ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, 19761da177e4SLinus Torvalds new_decode_dev(dev)); 19771da177e4SLinus Torvalds break; 19781da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 19794ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); 19801da177e4SLinus Torvalds break; 19811da177e4SLinus Torvalds case S_IFDIR: 19821da177e4SLinus Torvalds error = -EPERM; 19831da177e4SLinus Torvalds break; 19841da177e4SLinus Torvalds default: 19851da177e4SLinus Torvalds error = -EINVAL; 19861da177e4SLinus Torvalds } 19871da177e4SLinus Torvalds dput(dentry); 19881da177e4SLinus Torvalds } 19894ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 19901d957f9bSJan Blunck path_put(&nd.path); 19911da177e4SLinus Torvalds out: 19921da177e4SLinus Torvalds putname(tmp); 19931da177e4SLinus Torvalds 19941da177e4SLinus Torvalds return error; 19951da177e4SLinus Torvalds } 19961da177e4SLinus Torvalds 19975590ff0dSUlrich Drepper asmlinkage long sys_mknod(const char __user *filename, int mode, unsigned dev) 19985590ff0dSUlrich Drepper { 19995590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 20005590ff0dSUlrich Drepper } 20015590ff0dSUlrich Drepper 20021da177e4SLinus Torvalds int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 20031da177e4SLinus Torvalds { 20041da177e4SLinus Torvalds int error = may_create(dir, dentry, NULL); 20051da177e4SLinus Torvalds 20061da177e4SLinus Torvalds if (error) 20071da177e4SLinus Torvalds return error; 20081da177e4SLinus Torvalds 20091da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->mkdir) 20101da177e4SLinus Torvalds return -EPERM; 20111da177e4SLinus Torvalds 20121da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 20131da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 20141da177e4SLinus Torvalds if (error) 20151da177e4SLinus Torvalds return error; 20161da177e4SLinus Torvalds 20171da177e4SLinus Torvalds DQUOT_INIT(dir); 20181da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2019a74574aaSStephen Smalley if (!error) 2020f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 20211da177e4SLinus Torvalds return error; 20221da177e4SLinus Torvalds } 20231da177e4SLinus Torvalds 20245590ff0dSUlrich Drepper asmlinkage long sys_mkdirat(int dfd, const char __user *pathname, int mode) 20251da177e4SLinus Torvalds { 20261da177e4SLinus Torvalds int error = 0; 20271da177e4SLinus Torvalds char * tmp; 20286902d925SDave Hansen struct dentry *dentry; 20296902d925SDave Hansen struct nameidata nd; 20301da177e4SLinus Torvalds 20311da177e4SLinus Torvalds tmp = getname(pathname); 20321da177e4SLinus Torvalds error = PTR_ERR(tmp); 20336902d925SDave Hansen if (IS_ERR(tmp)) 20346902d925SDave Hansen goto out_err; 20351da177e4SLinus Torvalds 20365590ff0dSUlrich Drepper error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd); 20371da177e4SLinus Torvalds if (error) 20381da177e4SLinus Torvalds goto out; 20391da177e4SLinus Torvalds dentry = lookup_create(&nd, 1); 20401da177e4SLinus Torvalds error = PTR_ERR(dentry); 20416902d925SDave Hansen if (IS_ERR(dentry)) 20426902d925SDave Hansen goto out_unlock; 20436902d925SDave Hansen 20444ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 20451da177e4SLinus Torvalds mode &= ~current->fs->umask; 20464ac91378SJan Blunck error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); 20471da177e4SLinus Torvalds dput(dentry); 20486902d925SDave Hansen out_unlock: 20494ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 20501d957f9bSJan Blunck path_put(&nd.path); 20511da177e4SLinus Torvalds out: 20521da177e4SLinus Torvalds putname(tmp); 20536902d925SDave Hansen out_err: 20541da177e4SLinus Torvalds return error; 20551da177e4SLinus Torvalds } 20561da177e4SLinus Torvalds 20575590ff0dSUlrich Drepper asmlinkage long sys_mkdir(const char __user *pathname, int mode) 20585590ff0dSUlrich Drepper { 20595590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 20605590ff0dSUlrich Drepper } 20615590ff0dSUlrich Drepper 20621da177e4SLinus Torvalds /* 20631da177e4SLinus Torvalds * We try to drop the dentry early: we should have 20641da177e4SLinus Torvalds * a usage count of 2 if we're the only user of this 20651da177e4SLinus Torvalds * dentry, and if that is true (possibly after pruning 20661da177e4SLinus Torvalds * the dcache), then we drop the dentry now. 20671da177e4SLinus Torvalds * 20681da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 20691da177e4SLinus Torvalds * do a 20701da177e4SLinus Torvalds * 20711da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 20721da177e4SLinus Torvalds * return -EBUSY; 20731da177e4SLinus Torvalds * 20741da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 20751da177e4SLinus Torvalds * that is still in use by something else.. 20761da177e4SLinus Torvalds */ 20771da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 20781da177e4SLinus Torvalds { 20791da177e4SLinus Torvalds dget(dentry); 20801da177e4SLinus Torvalds shrink_dcache_parent(dentry); 20811da177e4SLinus Torvalds spin_lock(&dcache_lock); 20821da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 20831da177e4SLinus Torvalds if (atomic_read(&dentry->d_count) == 2) 20841da177e4SLinus Torvalds __d_drop(dentry); 20851da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 20861da177e4SLinus Torvalds spin_unlock(&dcache_lock); 20871da177e4SLinus Torvalds } 20881da177e4SLinus Torvalds 20891da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 20901da177e4SLinus Torvalds { 20911da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 20921da177e4SLinus Torvalds 20931da177e4SLinus Torvalds if (error) 20941da177e4SLinus Torvalds return error; 20951da177e4SLinus Torvalds 20961da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->rmdir) 20971da177e4SLinus Torvalds return -EPERM; 20981da177e4SLinus Torvalds 20991da177e4SLinus Torvalds DQUOT_INIT(dir); 21001da177e4SLinus Torvalds 21011b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 21021da177e4SLinus Torvalds dentry_unhash(dentry); 21031da177e4SLinus Torvalds if (d_mountpoint(dentry)) 21041da177e4SLinus Torvalds error = -EBUSY; 21051da177e4SLinus Torvalds else { 21061da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 21071da177e4SLinus Torvalds if (!error) { 21081da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 21091da177e4SLinus Torvalds if (!error) 21101da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 21111da177e4SLinus Torvalds } 21121da177e4SLinus Torvalds } 21131b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 21141da177e4SLinus Torvalds if (!error) { 21151da177e4SLinus Torvalds d_delete(dentry); 21161da177e4SLinus Torvalds } 21171da177e4SLinus Torvalds dput(dentry); 21181da177e4SLinus Torvalds 21191da177e4SLinus Torvalds return error; 21201da177e4SLinus Torvalds } 21211da177e4SLinus Torvalds 21225590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 21231da177e4SLinus Torvalds { 21241da177e4SLinus Torvalds int error = 0; 21251da177e4SLinus Torvalds char * name; 21261da177e4SLinus Torvalds struct dentry *dentry; 21271da177e4SLinus Torvalds struct nameidata nd; 21281da177e4SLinus Torvalds 21291da177e4SLinus Torvalds name = getname(pathname); 21301da177e4SLinus Torvalds if(IS_ERR(name)) 21311da177e4SLinus Torvalds return PTR_ERR(name); 21321da177e4SLinus Torvalds 21335590ff0dSUlrich Drepper error = do_path_lookup(dfd, name, LOOKUP_PARENT, &nd); 21341da177e4SLinus Torvalds if (error) 21351da177e4SLinus Torvalds goto exit; 21361da177e4SLinus Torvalds 21371da177e4SLinus Torvalds switch(nd.last_type) { 21381da177e4SLinus Torvalds case LAST_DOTDOT: 21391da177e4SLinus Torvalds error = -ENOTEMPTY; 21401da177e4SLinus Torvalds goto exit1; 21411da177e4SLinus Torvalds case LAST_DOT: 21421da177e4SLinus Torvalds error = -EINVAL; 21431da177e4SLinus Torvalds goto exit1; 21441da177e4SLinus Torvalds case LAST_ROOT: 21451da177e4SLinus Torvalds error = -EBUSY; 21461da177e4SLinus Torvalds goto exit1; 21471da177e4SLinus Torvalds } 21484ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 214949705b77SChristoph Hellwig dentry = lookup_hash(&nd); 21501da177e4SLinus Torvalds error = PTR_ERR(dentry); 21516902d925SDave Hansen if (IS_ERR(dentry)) 21526902d925SDave Hansen goto exit2; 21534ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 21541da177e4SLinus Torvalds dput(dentry); 21556902d925SDave Hansen exit2: 21564ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 21571da177e4SLinus Torvalds exit1: 21581d957f9bSJan Blunck path_put(&nd.path); 21591da177e4SLinus Torvalds exit: 21601da177e4SLinus Torvalds putname(name); 21611da177e4SLinus Torvalds return error; 21621da177e4SLinus Torvalds } 21631da177e4SLinus Torvalds 21645590ff0dSUlrich Drepper asmlinkage long sys_rmdir(const char __user *pathname) 21655590ff0dSUlrich Drepper { 21665590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 21675590ff0dSUlrich Drepper } 21685590ff0dSUlrich Drepper 21691da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 21701da177e4SLinus Torvalds { 21711da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 21721da177e4SLinus Torvalds 21731da177e4SLinus Torvalds if (error) 21741da177e4SLinus Torvalds return error; 21751da177e4SLinus Torvalds 21761da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->unlink) 21771da177e4SLinus Torvalds return -EPERM; 21781da177e4SLinus Torvalds 21791da177e4SLinus Torvalds DQUOT_INIT(dir); 21801da177e4SLinus Torvalds 21811b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 21821da177e4SLinus Torvalds if (d_mountpoint(dentry)) 21831da177e4SLinus Torvalds error = -EBUSY; 21841da177e4SLinus Torvalds else { 21851da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 21861da177e4SLinus Torvalds if (!error) 21871da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 21881da177e4SLinus Torvalds } 21891b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 21901da177e4SLinus Torvalds 21911da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 21921da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2193ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 21941da177e4SLinus Torvalds d_delete(dentry); 21951da177e4SLinus Torvalds } 21960eeca283SRobert Love 21971da177e4SLinus Torvalds return error; 21981da177e4SLinus Torvalds } 21991da177e4SLinus Torvalds 22001da177e4SLinus Torvalds /* 22011da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 22021b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 22031da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 22041da177e4SLinus Torvalds * while waiting on the I/O. 22051da177e4SLinus Torvalds */ 22065590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 22071da177e4SLinus Torvalds { 22081da177e4SLinus Torvalds int error = 0; 22091da177e4SLinus Torvalds char * name; 22101da177e4SLinus Torvalds struct dentry *dentry; 22111da177e4SLinus Torvalds struct nameidata nd; 22121da177e4SLinus Torvalds struct inode *inode = NULL; 22131da177e4SLinus Torvalds 22141da177e4SLinus Torvalds name = getname(pathname); 22151da177e4SLinus Torvalds if(IS_ERR(name)) 22161da177e4SLinus Torvalds return PTR_ERR(name); 22171da177e4SLinus Torvalds 22185590ff0dSUlrich Drepper error = do_path_lookup(dfd, name, LOOKUP_PARENT, &nd); 22191da177e4SLinus Torvalds if (error) 22201da177e4SLinus Torvalds goto exit; 22211da177e4SLinus Torvalds error = -EISDIR; 22221da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 22231da177e4SLinus Torvalds goto exit1; 22244ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 222549705b77SChristoph Hellwig dentry = lookup_hash(&nd); 22261da177e4SLinus Torvalds error = PTR_ERR(dentry); 22271da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 22281da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 22291da177e4SLinus Torvalds if (nd.last.name[nd.last.len]) 22301da177e4SLinus Torvalds goto slashes; 22311da177e4SLinus Torvalds inode = dentry->d_inode; 22321da177e4SLinus Torvalds if (inode) 22331da177e4SLinus Torvalds atomic_inc(&inode->i_count); 22344ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 22351da177e4SLinus Torvalds exit2: 22361da177e4SLinus Torvalds dput(dentry); 22371da177e4SLinus Torvalds } 22384ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 22391da177e4SLinus Torvalds if (inode) 22401da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 22411da177e4SLinus Torvalds exit1: 22421d957f9bSJan Blunck path_put(&nd.path); 22431da177e4SLinus Torvalds exit: 22441da177e4SLinus Torvalds putname(name); 22451da177e4SLinus Torvalds return error; 22461da177e4SLinus Torvalds 22471da177e4SLinus Torvalds slashes: 22481da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 22491da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 22501da177e4SLinus Torvalds goto exit2; 22511da177e4SLinus Torvalds } 22521da177e4SLinus Torvalds 22535590ff0dSUlrich Drepper asmlinkage long sys_unlinkat(int dfd, const char __user *pathname, int flag) 22545590ff0dSUlrich Drepper { 22555590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 22565590ff0dSUlrich Drepper return -EINVAL; 22575590ff0dSUlrich Drepper 22585590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 22595590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 22605590ff0dSUlrich Drepper 22615590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 22625590ff0dSUlrich Drepper } 22635590ff0dSUlrich Drepper 22645590ff0dSUlrich Drepper asmlinkage long sys_unlink(const char __user *pathname) 22655590ff0dSUlrich Drepper { 22665590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 22675590ff0dSUlrich Drepper } 22685590ff0dSUlrich Drepper 22691da177e4SLinus Torvalds int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname, int mode) 22701da177e4SLinus Torvalds { 22711da177e4SLinus Torvalds int error = may_create(dir, dentry, NULL); 22721da177e4SLinus Torvalds 22731da177e4SLinus Torvalds if (error) 22741da177e4SLinus Torvalds return error; 22751da177e4SLinus Torvalds 22761da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->symlink) 22771da177e4SLinus Torvalds return -EPERM; 22781da177e4SLinus Torvalds 22791da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 22801da177e4SLinus Torvalds if (error) 22811da177e4SLinus Torvalds return error; 22821da177e4SLinus Torvalds 22831da177e4SLinus Torvalds DQUOT_INIT(dir); 22841da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2285a74574aaSStephen Smalley if (!error) 2286f38aa942SAmy Griffis fsnotify_create(dir, dentry); 22871da177e4SLinus Torvalds return error; 22881da177e4SLinus Torvalds } 22891da177e4SLinus Torvalds 22905590ff0dSUlrich Drepper asmlinkage long sys_symlinkat(const char __user *oldname, 22915590ff0dSUlrich Drepper int newdfd, const char __user *newname) 22921da177e4SLinus Torvalds { 22931da177e4SLinus Torvalds int error = 0; 22941da177e4SLinus Torvalds char * from; 22951da177e4SLinus Torvalds char * to; 22966902d925SDave Hansen struct dentry *dentry; 22976902d925SDave Hansen struct nameidata nd; 22981da177e4SLinus Torvalds 22991da177e4SLinus Torvalds from = getname(oldname); 23001da177e4SLinus Torvalds if(IS_ERR(from)) 23011da177e4SLinus Torvalds return PTR_ERR(from); 23021da177e4SLinus Torvalds to = getname(newname); 23031da177e4SLinus Torvalds error = PTR_ERR(to); 23046902d925SDave Hansen if (IS_ERR(to)) 23056902d925SDave Hansen goto out_putname; 23061da177e4SLinus Torvalds 23075590ff0dSUlrich Drepper error = do_path_lookup(newdfd, to, LOOKUP_PARENT, &nd); 23081da177e4SLinus Torvalds if (error) 23091da177e4SLinus Torvalds goto out; 23101da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 23111da177e4SLinus Torvalds error = PTR_ERR(dentry); 23126902d925SDave Hansen if (IS_ERR(dentry)) 23136902d925SDave Hansen goto out_unlock; 23146902d925SDave Hansen 23154ac91378SJan Blunck error = vfs_symlink(nd.path.dentry->d_inode, dentry, from, S_IALLUGO); 23161da177e4SLinus Torvalds dput(dentry); 23176902d925SDave Hansen out_unlock: 23184ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 23191d957f9bSJan Blunck path_put(&nd.path); 23201da177e4SLinus Torvalds out: 23211da177e4SLinus Torvalds putname(to); 23226902d925SDave Hansen out_putname: 23231da177e4SLinus Torvalds putname(from); 23241da177e4SLinus Torvalds return error; 23251da177e4SLinus Torvalds } 23261da177e4SLinus Torvalds 23275590ff0dSUlrich Drepper asmlinkage long sys_symlink(const char __user *oldname, const char __user *newname) 23285590ff0dSUlrich Drepper { 23295590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 23305590ff0dSUlrich Drepper } 23315590ff0dSUlrich Drepper 23321da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 23331da177e4SLinus Torvalds { 23341da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 23351da177e4SLinus Torvalds int error; 23361da177e4SLinus Torvalds 23371da177e4SLinus Torvalds if (!inode) 23381da177e4SLinus Torvalds return -ENOENT; 23391da177e4SLinus Torvalds 23401da177e4SLinus Torvalds error = may_create(dir, new_dentry, NULL); 23411da177e4SLinus Torvalds if (error) 23421da177e4SLinus Torvalds return error; 23431da177e4SLinus Torvalds 23441da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 23451da177e4SLinus Torvalds return -EXDEV; 23461da177e4SLinus Torvalds 23471da177e4SLinus Torvalds /* 23481da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 23491da177e4SLinus Torvalds */ 23501da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 23511da177e4SLinus Torvalds return -EPERM; 23521da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->link) 23531da177e4SLinus Torvalds return -EPERM; 23541da177e4SLinus Torvalds if (S_ISDIR(old_dentry->d_inode->i_mode)) 23551da177e4SLinus Torvalds return -EPERM; 23561da177e4SLinus Torvalds 23571da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 23581da177e4SLinus Torvalds if (error) 23591da177e4SLinus Torvalds return error; 23601da177e4SLinus Torvalds 23611b1dcc1bSJes Sorensen mutex_lock(&old_dentry->d_inode->i_mutex); 23621da177e4SLinus Torvalds DQUOT_INIT(dir); 23631da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 23641b1dcc1bSJes Sorensen mutex_unlock(&old_dentry->d_inode->i_mutex); 2365e31e14ecSStephen Smalley if (!error) 2366ece95912SJan Kara fsnotify_link(dir, old_dentry->d_inode, new_dentry); 23671da177e4SLinus Torvalds return error; 23681da177e4SLinus Torvalds } 23691da177e4SLinus Torvalds 23701da177e4SLinus Torvalds /* 23711da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 23721da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 23731da177e4SLinus Torvalds * newname. --KAB 23741da177e4SLinus Torvalds * 23751da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 23761da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 23771da177e4SLinus Torvalds * and other special files. --ADM 23781da177e4SLinus Torvalds */ 23795590ff0dSUlrich Drepper asmlinkage long sys_linkat(int olddfd, const char __user *oldname, 2380c04030e1SUlrich Drepper int newdfd, const char __user *newname, 2381c04030e1SUlrich Drepper int flags) 23821da177e4SLinus Torvalds { 23831da177e4SLinus Torvalds struct dentry *new_dentry; 23841da177e4SLinus Torvalds struct nameidata nd, old_nd; 23851da177e4SLinus Torvalds int error; 23861da177e4SLinus Torvalds char * to; 23871da177e4SLinus Torvalds 238845c9b11aSUlrich Drepper if ((flags & ~AT_SYMLINK_FOLLOW) != 0) 2389c04030e1SUlrich Drepper return -EINVAL; 2390c04030e1SUlrich Drepper 23911da177e4SLinus Torvalds to = getname(newname); 23921da177e4SLinus Torvalds if (IS_ERR(to)) 23931da177e4SLinus Torvalds return PTR_ERR(to); 23941da177e4SLinus Torvalds 239545c9b11aSUlrich Drepper error = __user_walk_fd(olddfd, oldname, 239645c9b11aSUlrich Drepper flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0, 239745c9b11aSUlrich Drepper &old_nd); 23981da177e4SLinus Torvalds if (error) 23991da177e4SLinus Torvalds goto exit; 24005590ff0dSUlrich Drepper error = do_path_lookup(newdfd, to, LOOKUP_PARENT, &nd); 24011da177e4SLinus Torvalds if (error) 24021da177e4SLinus Torvalds goto out; 24031da177e4SLinus Torvalds error = -EXDEV; 24044ac91378SJan Blunck if (old_nd.path.mnt != nd.path.mnt) 24051da177e4SLinus Torvalds goto out_release; 24061da177e4SLinus Torvalds new_dentry = lookup_create(&nd, 0); 24071da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 24086902d925SDave Hansen if (IS_ERR(new_dentry)) 24096902d925SDave Hansen goto out_unlock; 24104ac91378SJan Blunck error = vfs_link(old_nd.path.dentry, nd.path.dentry->d_inode, new_dentry); 24111da177e4SLinus Torvalds dput(new_dentry); 24126902d925SDave Hansen out_unlock: 24134ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 24141da177e4SLinus Torvalds out_release: 24151d957f9bSJan Blunck path_put(&nd.path); 24161da177e4SLinus Torvalds out: 24171d957f9bSJan Blunck path_put(&old_nd.path); 24181da177e4SLinus Torvalds exit: 24191da177e4SLinus Torvalds putname(to); 24201da177e4SLinus Torvalds 24211da177e4SLinus Torvalds return error; 24221da177e4SLinus Torvalds } 24231da177e4SLinus Torvalds 24245590ff0dSUlrich Drepper asmlinkage long sys_link(const char __user *oldname, const char __user *newname) 24255590ff0dSUlrich Drepper { 2426c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 24275590ff0dSUlrich Drepper } 24285590ff0dSUlrich Drepper 24291da177e4SLinus Torvalds /* 24301da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 24311da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 24321da177e4SLinus Torvalds * Problems: 24331da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 24341da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 24351da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 2436a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 24371da177e4SLinus Torvalds * story. 24381da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 24391b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 24401da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 24411da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 2442a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 24431da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 24441da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 24451da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 2446a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 24471da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 24481da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 24491da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 24501da177e4SLinus Torvalds * d) some filesystems don't support opened-but-unlinked directories, 24511da177e4SLinus Torvalds * either because of layout or because they are not ready to deal with 24521da177e4SLinus Torvalds * all cases correctly. The latter will be fixed (taking this sort of 24531da177e4SLinus Torvalds * stuff into VFS), but the former is not going away. Solution: the same 24541da177e4SLinus Torvalds * trick as in rmdir(). 24551da177e4SLinus Torvalds * e) conversion from fhandle to dentry may come in the wrong moment - when 24561b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 24571da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 24581b1dcc1bSJes Sorensen * ->i_mutex on parents, which works but leads to some truely excessive 24591da177e4SLinus Torvalds * locking]. 24601da177e4SLinus Torvalds */ 246175c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 24621da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 24631da177e4SLinus Torvalds { 24641da177e4SLinus Torvalds int error = 0; 24651da177e4SLinus Torvalds struct inode *target; 24661da177e4SLinus Torvalds 24671da177e4SLinus Torvalds /* 24681da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 24691da177e4SLinus Torvalds * we'll need to flip '..'. 24701da177e4SLinus Torvalds */ 24711da177e4SLinus Torvalds if (new_dir != old_dir) { 24721da177e4SLinus Torvalds error = permission(old_dentry->d_inode, MAY_WRITE, NULL); 24731da177e4SLinus Torvalds if (error) 24741da177e4SLinus Torvalds return error; 24751da177e4SLinus Torvalds } 24761da177e4SLinus Torvalds 24771da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 24781da177e4SLinus Torvalds if (error) 24791da177e4SLinus Torvalds return error; 24801da177e4SLinus Torvalds 24811da177e4SLinus Torvalds target = new_dentry->d_inode; 24821da177e4SLinus Torvalds if (target) { 24831b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 24841da177e4SLinus Torvalds dentry_unhash(new_dentry); 24851da177e4SLinus Torvalds } 24861da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 24871da177e4SLinus Torvalds error = -EBUSY; 24881da177e4SLinus Torvalds else 24891da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 24901da177e4SLinus Torvalds if (target) { 24911da177e4SLinus Torvalds if (!error) 24921da177e4SLinus Torvalds target->i_flags |= S_DEAD; 24931b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 24941da177e4SLinus Torvalds if (d_unhashed(new_dentry)) 24951da177e4SLinus Torvalds d_rehash(new_dentry); 24961da177e4SLinus Torvalds dput(new_dentry); 24971da177e4SLinus Torvalds } 2498e31e14ecSStephen Smalley if (!error) 2499349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 25001da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 25011da177e4SLinus Torvalds return error; 25021da177e4SLinus Torvalds } 25031da177e4SLinus Torvalds 250475c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 25051da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 25061da177e4SLinus Torvalds { 25071da177e4SLinus Torvalds struct inode *target; 25081da177e4SLinus Torvalds int error; 25091da177e4SLinus Torvalds 25101da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 25111da177e4SLinus Torvalds if (error) 25121da177e4SLinus Torvalds return error; 25131da177e4SLinus Torvalds 25141da177e4SLinus Torvalds dget(new_dentry); 25151da177e4SLinus Torvalds target = new_dentry->d_inode; 25161da177e4SLinus Torvalds if (target) 25171b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 25181da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 25191da177e4SLinus Torvalds error = -EBUSY; 25201da177e4SLinus Torvalds else 25211da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 25221da177e4SLinus Torvalds if (!error) { 2523349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 25241da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 25251da177e4SLinus Torvalds } 25261da177e4SLinus Torvalds if (target) 25271b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 25281da177e4SLinus Torvalds dput(new_dentry); 25291da177e4SLinus Torvalds return error; 25301da177e4SLinus Torvalds } 25311da177e4SLinus Torvalds 25321da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 25331da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 25341da177e4SLinus Torvalds { 25351da177e4SLinus Torvalds int error; 25361da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 25370eeca283SRobert Love const char *old_name; 25381da177e4SLinus Torvalds 25391da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 25401da177e4SLinus Torvalds return 0; 25411da177e4SLinus Torvalds 25421da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 25431da177e4SLinus Torvalds if (error) 25441da177e4SLinus Torvalds return error; 25451da177e4SLinus Torvalds 25461da177e4SLinus Torvalds if (!new_dentry->d_inode) 25471da177e4SLinus Torvalds error = may_create(new_dir, new_dentry, NULL); 25481da177e4SLinus Torvalds else 25491da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 25501da177e4SLinus Torvalds if (error) 25511da177e4SLinus Torvalds return error; 25521da177e4SLinus Torvalds 25531da177e4SLinus Torvalds if (!old_dir->i_op || !old_dir->i_op->rename) 25541da177e4SLinus Torvalds return -EPERM; 25551da177e4SLinus Torvalds 25561da177e4SLinus Torvalds DQUOT_INIT(old_dir); 25571da177e4SLinus Torvalds DQUOT_INIT(new_dir); 25581da177e4SLinus Torvalds 25590eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 25600eeca283SRobert Love 25611da177e4SLinus Torvalds if (is_dir) 25621da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 25631da177e4SLinus Torvalds else 25641da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 25651da177e4SLinus Torvalds if (!error) { 25660eeca283SRobert Love const char *new_name = old_dentry->d_name.name; 256789204c40SJohn McCutchan fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir, 25685a190ae6SAl Viro new_dentry->d_inode, old_dentry); 25691da177e4SLinus Torvalds } 25700eeca283SRobert Love fsnotify_oldname_free(old_name); 25710eeca283SRobert Love 25721da177e4SLinus Torvalds return error; 25731da177e4SLinus Torvalds } 25741da177e4SLinus Torvalds 25755590ff0dSUlrich Drepper static int do_rename(int olddfd, const char *oldname, 25765590ff0dSUlrich Drepper int newdfd, const char *newname) 25771da177e4SLinus Torvalds { 25781da177e4SLinus Torvalds int error = 0; 25791da177e4SLinus Torvalds struct dentry * old_dir, * new_dir; 25801da177e4SLinus Torvalds struct dentry * old_dentry, *new_dentry; 25811da177e4SLinus Torvalds struct dentry * trap; 25821da177e4SLinus Torvalds struct nameidata oldnd, newnd; 25831da177e4SLinus Torvalds 25845590ff0dSUlrich Drepper error = do_path_lookup(olddfd, oldname, LOOKUP_PARENT, &oldnd); 25851da177e4SLinus Torvalds if (error) 25861da177e4SLinus Torvalds goto exit; 25871da177e4SLinus Torvalds 25885590ff0dSUlrich Drepper error = do_path_lookup(newdfd, newname, LOOKUP_PARENT, &newnd); 25891da177e4SLinus Torvalds if (error) 25901da177e4SLinus Torvalds goto exit1; 25911da177e4SLinus Torvalds 25921da177e4SLinus Torvalds error = -EXDEV; 25934ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 25941da177e4SLinus Torvalds goto exit2; 25951da177e4SLinus Torvalds 25964ac91378SJan Blunck old_dir = oldnd.path.dentry; 25971da177e4SLinus Torvalds error = -EBUSY; 25981da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 25991da177e4SLinus Torvalds goto exit2; 26001da177e4SLinus Torvalds 26014ac91378SJan Blunck new_dir = newnd.path.dentry; 26021da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 26031da177e4SLinus Torvalds goto exit2; 26041da177e4SLinus Torvalds 26051da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 26061da177e4SLinus Torvalds 260749705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 26081da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 26091da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 26101da177e4SLinus Torvalds goto exit3; 26111da177e4SLinus Torvalds /* source must exist */ 26121da177e4SLinus Torvalds error = -ENOENT; 26131da177e4SLinus Torvalds if (!old_dentry->d_inode) 26141da177e4SLinus Torvalds goto exit4; 26151da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 26161da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 26171da177e4SLinus Torvalds error = -ENOTDIR; 26181da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 26191da177e4SLinus Torvalds goto exit4; 26201da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 26211da177e4SLinus Torvalds goto exit4; 26221da177e4SLinus Torvalds } 26231da177e4SLinus Torvalds /* source should not be ancestor of target */ 26241da177e4SLinus Torvalds error = -EINVAL; 26251da177e4SLinus Torvalds if (old_dentry == trap) 26261da177e4SLinus Torvalds goto exit4; 262749705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 26281da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 26291da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 26301da177e4SLinus Torvalds goto exit4; 26311da177e4SLinus Torvalds /* target should not be an ancestor of source */ 26321da177e4SLinus Torvalds error = -ENOTEMPTY; 26331da177e4SLinus Torvalds if (new_dentry == trap) 26341da177e4SLinus Torvalds goto exit5; 26351da177e4SLinus Torvalds 26361da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 26371da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 26381da177e4SLinus Torvalds exit5: 26391da177e4SLinus Torvalds dput(new_dentry); 26401da177e4SLinus Torvalds exit4: 26411da177e4SLinus Torvalds dput(old_dentry); 26421da177e4SLinus Torvalds exit3: 26431da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 26441da177e4SLinus Torvalds exit2: 26451d957f9bSJan Blunck path_put(&newnd.path); 26461da177e4SLinus Torvalds exit1: 26471d957f9bSJan Blunck path_put(&oldnd.path); 26481da177e4SLinus Torvalds exit: 26491da177e4SLinus Torvalds return error; 26501da177e4SLinus Torvalds } 26511da177e4SLinus Torvalds 26525590ff0dSUlrich Drepper asmlinkage long sys_renameat(int olddfd, const char __user *oldname, 26535590ff0dSUlrich Drepper int newdfd, const char __user *newname) 26541da177e4SLinus Torvalds { 26551da177e4SLinus Torvalds int error; 26561da177e4SLinus Torvalds char * from; 26571da177e4SLinus Torvalds char * to; 26581da177e4SLinus Torvalds 26591da177e4SLinus Torvalds from = getname(oldname); 26601da177e4SLinus Torvalds if(IS_ERR(from)) 26611da177e4SLinus Torvalds return PTR_ERR(from); 26621da177e4SLinus Torvalds to = getname(newname); 26631da177e4SLinus Torvalds error = PTR_ERR(to); 26641da177e4SLinus Torvalds if (!IS_ERR(to)) { 26655590ff0dSUlrich Drepper error = do_rename(olddfd, from, newdfd, to); 26661da177e4SLinus Torvalds putname(to); 26671da177e4SLinus Torvalds } 26681da177e4SLinus Torvalds putname(from); 26691da177e4SLinus Torvalds return error; 26701da177e4SLinus Torvalds } 26711da177e4SLinus Torvalds 26725590ff0dSUlrich Drepper asmlinkage long sys_rename(const char __user *oldname, const char __user *newname) 26735590ff0dSUlrich Drepper { 26745590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 26755590ff0dSUlrich Drepper } 26765590ff0dSUlrich Drepper 26771da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 26781da177e4SLinus Torvalds { 26791da177e4SLinus Torvalds int len; 26801da177e4SLinus Torvalds 26811da177e4SLinus Torvalds len = PTR_ERR(link); 26821da177e4SLinus Torvalds if (IS_ERR(link)) 26831da177e4SLinus Torvalds goto out; 26841da177e4SLinus Torvalds 26851da177e4SLinus Torvalds len = strlen(link); 26861da177e4SLinus Torvalds if (len > (unsigned) buflen) 26871da177e4SLinus Torvalds len = buflen; 26881da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 26891da177e4SLinus Torvalds len = -EFAULT; 26901da177e4SLinus Torvalds out: 26911da177e4SLinus Torvalds return len; 26921da177e4SLinus Torvalds } 26931da177e4SLinus Torvalds 26941da177e4SLinus Torvalds /* 26951da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 26961da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 26971da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 26981da177e4SLinus Torvalds */ 26991da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 27001da177e4SLinus Torvalds { 27011da177e4SLinus Torvalds struct nameidata nd; 2702cc314eefSLinus Torvalds void *cookie; 2703cc314eefSLinus Torvalds 27041da177e4SLinus Torvalds nd.depth = 0; 2705cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 2706cc314eefSLinus Torvalds if (!IS_ERR(cookie)) { 2707cc314eefSLinus Torvalds int res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 27081da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 2709cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 2710cc314eefSLinus Torvalds cookie = ERR_PTR(res); 27111da177e4SLinus Torvalds } 2712cc314eefSLinus Torvalds return PTR_ERR(cookie); 27131da177e4SLinus Torvalds } 27141da177e4SLinus Torvalds 27151da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 27161da177e4SLinus Torvalds { 27171da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 27181da177e4SLinus Torvalds } 27191da177e4SLinus Torvalds 27201da177e4SLinus Torvalds /* get the link contents into pagecache */ 27211da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 27221da177e4SLinus Torvalds { 27231da177e4SLinus Torvalds struct page * page; 27241da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 2725090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 27261da177e4SLinus Torvalds if (IS_ERR(page)) 27276fe6900eSNick Piggin return (char*)page; 27281da177e4SLinus Torvalds *ppage = page; 27291da177e4SLinus Torvalds return kmap(page); 27301da177e4SLinus Torvalds } 27311da177e4SLinus Torvalds 27321da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 27331da177e4SLinus Torvalds { 27341da177e4SLinus Torvalds struct page *page = NULL; 27351da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 27361da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 27371da177e4SLinus Torvalds if (page) { 27381da177e4SLinus Torvalds kunmap(page); 27391da177e4SLinus Torvalds page_cache_release(page); 27401da177e4SLinus Torvalds } 27411da177e4SLinus Torvalds return res; 27421da177e4SLinus Torvalds } 27431da177e4SLinus Torvalds 2744cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 27451da177e4SLinus Torvalds { 2746cc314eefSLinus Torvalds struct page *page = NULL; 27471da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 2748cc314eefSLinus Torvalds return page; 27491da177e4SLinus Torvalds } 27501da177e4SLinus Torvalds 2751cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 27521da177e4SLinus Torvalds { 2753cc314eefSLinus Torvalds struct page *page = cookie; 2754cc314eefSLinus Torvalds 2755cc314eefSLinus Torvalds if (page) { 27561da177e4SLinus Torvalds kunmap(page); 27571da177e4SLinus Torvalds page_cache_release(page); 27581da177e4SLinus Torvalds } 27591da177e4SLinus Torvalds } 27601da177e4SLinus Torvalds 27610adb25d2SKirill Korotaev int __page_symlink(struct inode *inode, const char *symname, int len, 27620adb25d2SKirill Korotaev gfp_t gfp_mask) 27631da177e4SLinus Torvalds { 27641da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 27650adb25d2SKirill Korotaev struct page *page; 2766afddba49SNick Piggin void *fsdata; 2767beb497abSDmitriy Monakhov int err; 27681da177e4SLinus Torvalds char *kaddr; 27691da177e4SLinus Torvalds 27707e53cac4SNeilBrown retry: 2771afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 2772afddba49SNick Piggin AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata); 27731da177e4SLinus Torvalds if (err) 2774afddba49SNick Piggin goto fail; 2775afddba49SNick Piggin 27761da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 27771da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 27781da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 2779afddba49SNick Piggin 2780afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 2781afddba49SNick Piggin page, fsdata); 27821da177e4SLinus Torvalds if (err < 0) 27831da177e4SLinus Torvalds goto fail; 2784afddba49SNick Piggin if (err < len-1) 2785afddba49SNick Piggin goto retry; 2786afddba49SNick Piggin 27871da177e4SLinus Torvalds mark_inode_dirty(inode); 27881da177e4SLinus Torvalds return 0; 27891da177e4SLinus Torvalds fail: 27901da177e4SLinus Torvalds return err; 27911da177e4SLinus Torvalds } 27921da177e4SLinus Torvalds 27930adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 27940adb25d2SKirill Korotaev { 27950adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 27960adb25d2SKirill Korotaev mapping_gfp_mask(inode->i_mapping)); 27970adb25d2SKirill Korotaev } 27980adb25d2SKirill Korotaev 279992e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 28001da177e4SLinus Torvalds .readlink = generic_readlink, 28011da177e4SLinus Torvalds .follow_link = page_follow_link_light, 28021da177e4SLinus Torvalds .put_link = page_put_link, 28031da177e4SLinus Torvalds }; 28041da177e4SLinus Torvalds 28051da177e4SLinus Torvalds EXPORT_SYMBOL(__user_walk); 28065590ff0dSUlrich Drepper EXPORT_SYMBOL(__user_walk_fd); 28071da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 28081da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 28091da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 28101da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 28111da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 28121da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 28131da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 28141da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 28151da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 28160adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 28171da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 28181da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 28191da177e4SLinus Torvalds EXPORT_SYMBOL(path_lookup); 282016f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 28211da177e4SLinus Torvalds EXPORT_SYMBOL(permission); 2822e4543eddSChristoph Hellwig EXPORT_SYMBOL(vfs_permission); 28238c744fb8SChristoph Hellwig EXPORT_SYMBOL(file_permission); 28241da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 28251da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 28261da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 28271da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 28281da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 28291da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 28301da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 28311da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 28321da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 28331da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 28341da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 28351da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 28361da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 28371da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 2838