diff options
Diffstat (limited to 'fs/namei.c')
-rw-r--r-- | fs/namei.c | 171 |
1 files changed, 139 insertions, 32 deletions
diff --git a/fs/namei.c b/fs/namei.c index 043d587216b..6dbbd42d8b9 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -28,6 +28,7 @@ #include <linux/syscalls.h> #include <linux/mount.h> #include <linux/audit.h> +#include <linux/file.h> #include <asm/namei.h> #include <asm/uaccess.h> @@ -255,6 +256,38 @@ int permission(struct inode *inode, int mask, struct nameidata *nd) return security_inode_permission(inode, mask, nd); } +/** + * vfs_permission - check for access rights to a given path + * @nd: lookup result that describes the path + * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) + * + * Used to check for read/write/execute permissions on a path. + * We use "fsuid" for this, letting us set arbitrary permissions + * for filesystem access without changing the "normal" uids which + * are used for other things. + */ +int vfs_permission(struct nameidata *nd, int mask) +{ + return permission(nd->dentry->d_inode, mask, nd); +} + +/** + * file_permission - check for additional access rights to a given file + * @file: file to check access rights for + * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) + * + * Used to check for read/write/execute permissions on an already opened + * file. + * + * Note: + * Do not use this function in new code. All access checks should + * be done using vfs_permission(). + */ +int file_permission(struct file *file, int mask) +{ + return permission(file->f_dentry->d_inode, mask, NULL); +} + /* * get_write_access() gets write permission for a file. * put_write_access() releases this write permission. @@ -317,6 +350,18 @@ void path_release_on_umount(struct nameidata *nd) mntput_no_expire(nd->mnt); } +/** + * release_open_intent - free up open intent resources + * @nd: pointer to nameidata + */ +void release_open_intent(struct nameidata *nd) +{ + if (nd->intent.open.file->f_dentry == NULL) + put_filp(nd->intent.open.file); + else + fput(nd->intent.open.file); +} + /* * Internal lookup() using the new generic dcache. * SMP-safe @@ -750,10 +795,10 @@ static fastcall int __link_path_walk(const char * name, struct nameidata *nd) struct qstr this; unsigned int c; + nd->flags |= LOOKUP_CONTINUE; err = exec_permission_lite(inode, nd); - if (err == -EAGAIN) { - err = permission(inode, MAY_EXEC, nd); - } + if (err == -EAGAIN) + err = vfs_permission(nd, MAY_EXEC); if (err) break; @@ -802,7 +847,6 @@ static fastcall int __link_path_walk(const char * name, struct nameidata *nd) if (err < 0) break; } - nd->flags |= LOOKUP_CONTINUE; /* This does the actual lookups.. */ err = do_lookup(nd, &this, &next); if (err) @@ -1052,6 +1096,71 @@ out: return retval; } +static int __path_lookup_intent_open(const char *name, unsigned int lookup_flags, + struct nameidata *nd, int open_flags, int create_mode) +{ + struct file *filp = get_empty_filp(); + int err; + + if (filp == NULL) + return -ENFILE; + nd->intent.open.file = filp; + nd->intent.open.flags = open_flags; + nd->intent.open.create_mode = create_mode; + err = path_lookup(name, lookup_flags|LOOKUP_OPEN, nd); + if (IS_ERR(nd->intent.open.file)) { + if (err == 0) { + err = PTR_ERR(nd->intent.open.file); + path_release(nd); + } + } else if (err != 0) + release_open_intent(nd); + return err; +} + +/** + * path_lookup_open - lookup a file path with open intent + * @name: pointer to file name + * @lookup_flags: lookup intent flags + * @nd: pointer to nameidata + * @open_flags: open intent flags + */ +int path_lookup_open(const char *name, unsigned int lookup_flags, + struct nameidata *nd, int open_flags) +{ + return __path_lookup_intent_open(name, lookup_flags, nd, + open_flags, 0); +} + +/** + * path_lookup_create - lookup a file path with open + create intent + * @name: pointer to file name + * @lookup_flags: lookup intent flags + * @nd: pointer to nameidata + * @open_flags: open intent flags + * @create_mode: create intent flags + */ +static int path_lookup_create(const char *name, unsigned int lookup_flags, + struct nameidata *nd, int open_flags, + int create_mode) +{ + return __path_lookup_intent_open(name, lookup_flags|LOOKUP_CREATE, nd, + open_flags, create_mode); +} + +int __user_path_lookup_open(const char __user *name, unsigned int lookup_flags, + struct nameidata *nd, int open_flags) +{ + char *tmp = getname(name); + int err = PTR_ERR(tmp); + + if (!IS_ERR(tmp)) { + err = __path_lookup_intent_open(tmp, lookup_flags, nd, open_flags, 0); + putname(tmp); + } + return err; +} + /* * Restricted form of lookup. Doesn't follow links, single-component only, * needs parent already locked. Doesn't follow mounts. @@ -1096,9 +1205,9 @@ out: return dentry; } -struct dentry * lookup_hash(struct qstr *name, struct dentry * base) +struct dentry * lookup_hash(struct nameidata *nd) { - return __lookup_hash(name, base, NULL); + return __lookup_hash(&nd->last, nd->dentry, nd); } /* SMP-safe */ @@ -1122,7 +1231,7 @@ struct dentry * lookup_one_len(const char * name, struct dentry * base, int len) } this.hash = end_name_hash(hash); - return lookup_hash(&this, base); + return __lookup_hash(&this, base, NULL); access: return ERR_PTR(-EACCES); } @@ -1234,9 +1343,6 @@ static inline int may_create(struct inode *dir, struct dentry *child, } /* - * Special case: O_CREAT|O_EXCL implies O_NOFOLLOW for security - * reasons. - * * O_DIRECTORY translates into forcing a directory lookup. */ static inline int lookup_flags(unsigned int f) @@ -1246,9 +1352,6 @@ static inline int lookup_flags(unsigned int f) if (f & O_NOFOLLOW) retval &= ~LOOKUP_FOLLOW; - if ((f & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL)) - retval &= ~LOOKUP_FOLLOW; - if (f & O_DIRECTORY) retval |= LOOKUP_DIRECTORY; @@ -1336,7 +1439,7 @@ int may_open(struct nameidata *nd, int acc_mode, int flag) if (S_ISDIR(inode->i_mode) && (flag & FMODE_WRITE)) return -EISDIR; - error = permission(inode, acc_mode, nd); + error = vfs_permission(nd, acc_mode); if (error) return error; @@ -1388,7 +1491,7 @@ int may_open(struct nameidata *nd, int acc_mode, int flag) if (!error) { DQUOT_INIT(inode); - error = do_truncate(dentry, 0); + error = do_truncate(dentry, 0, NULL); } put_write_access(inode); if (error) @@ -1416,27 +1519,27 @@ int may_open(struct nameidata *nd, int acc_mode, int flag) */ int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd) { - int acc_mode, error = 0; + int acc_mode, error; struct path path; struct dentry *dir; int count = 0; acc_mode = ACC_MODE(flag); + /* O_TRUNC implies we need access checks for write permissions */ + if (flag & O_TRUNC) + acc_mode |= MAY_WRITE; + /* Allow the LSM permission hook to distinguish append access from general write access. */ if (flag & O_APPEND) acc_mode |= MAY_APPEND; - /* Fill in the open() intent data */ - nd->intent.open.flags = flag; - nd->intent.open.create_mode = mode; - /* * The simplest case - just a plain lookup. */ if (!(flag & O_CREAT)) { - error = path_lookup(pathname, lookup_flags(flag)|LOOKUP_OPEN, nd); + error = path_lookup_open(pathname, lookup_flags(flag), nd, flag); if (error) return error; goto ok; @@ -1445,7 +1548,7 @@ int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd) /* * Create - we need to know the parent. */ - error = path_lookup(pathname, LOOKUP_PARENT|LOOKUP_OPEN|LOOKUP_CREATE, nd); + error = path_lookup_create(pathname, LOOKUP_PARENT, nd, flag, mode); if (error) return error; @@ -1461,7 +1564,7 @@ int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd) dir = nd->dentry; nd->flags &= ~LOOKUP_PARENT; down(&dir->d_inode->i_sem); - path.dentry = __lookup_hash(&nd->last, nd->dentry, nd); + path.dentry = lookup_hash(nd); path.mnt = nd->mnt; do_last: @@ -1520,6 +1623,8 @@ ok: exit_dput: dput_path(&path, nd); exit: + if (!IS_ERR(nd->intent.open.file)) + release_open_intent(nd); path_release(nd); return error; @@ -1551,19 +1656,19 @@ do_link: if (nd->last_type != LAST_NORM) goto exit; if (nd->last.name[nd->last.len]) { - putname(nd->last.name); + __putname(nd->last.name); goto exit; } error = -ELOOP; if (count++==32) { - putname(nd->last.name); + __putname(nd->last.name); goto exit; } dir = nd->dentry; down(&dir->d_inode->i_sem); - path.dentry = __lookup_hash(&nd->last, nd->dentry, nd); + path.dentry = lookup_hash(nd); path.mnt = nd->mnt; - putname(nd->last.name); + __putname(nd->last.name); goto do_last; } @@ -1593,7 +1698,7 @@ struct dentry *lookup_create(struct nameidata *nd, int is_dir) /* * Do the final lookup. */ - dentry = lookup_hash(&nd->last, nd->dentry); + dentry = lookup_hash(nd); if (IS_ERR(dentry)) goto fail; @@ -1828,7 +1933,7 @@ asmlinkage long sys_rmdir(const char __user * pathname) goto exit1; } down(&nd.dentry->d_inode->i_sem); - dentry = lookup_hash(&nd.last, nd.dentry); + dentry = lookup_hash(&nd); error = PTR_ERR(dentry); if (!IS_ERR(dentry)) { error = vfs_rmdir(nd.dentry->d_inode, dentry); @@ -1897,7 +2002,7 @@ asmlinkage long sys_unlink(const char __user * pathname) if (nd.last_type != LAST_NORM) goto exit1; down(&nd.dentry->d_inode->i_sem); - dentry = lookup_hash(&nd.last, nd.dentry); + dentry = lookup_hash(&nd); error = PTR_ERR(dentry); if (!IS_ERR(dentry)) { /* Why not before? Because we want correct error value */ @@ -2240,7 +2345,7 @@ static inline int do_rename(const char * oldname, const char * newname) trap = lock_rename(new_dir, old_dir); - old_dentry = lookup_hash(&oldnd.last, old_dir); + old_dentry = lookup_hash(&oldnd); error = PTR_ERR(old_dentry); if (IS_ERR(old_dentry)) goto exit3; @@ -2260,7 +2365,7 @@ static inline int do_rename(const char * oldname, const char * newname) error = -EINVAL; if (old_dentry == trap) goto exit4; - new_dentry = lookup_hash(&newnd.last, new_dir); + new_dentry = lookup_hash(&newnd); error = PTR_ERR(new_dentry); if (IS_ERR(new_dentry)) goto exit4; @@ -2463,6 +2568,8 @@ EXPORT_SYMBOL(path_lookup); EXPORT_SYMBOL(path_release); EXPORT_SYMBOL(path_walk); EXPORT_SYMBOL(permission); +EXPORT_SYMBOL(vfs_permission); +EXPORT_SYMBOL(file_permission); EXPORT_SYMBOL(unlock_rename); EXPORT_SYMBOL(vfs_create); EXPORT_SYMBOL(vfs_follow_link); |