new helpers: kern_path_create/user_path_create

combination of kern_path_parent() and lookup_create().  Does *not*
expose struct nameidata to caller.  Syscalls converted to that...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

4 files changed, 106 insertions, 137 deletions

diff --git a/fs/namei.c b/fs/namei.c
index f49d6ab..b292eb0 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2311,6 +2311,35 @@ fail:
 }
 EXPORT_SYMBOL_GPL(lookup_create);
 
+struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, int is_dir)
+{
+	struct nameidata nd;
+	struct dentry *res;
+	int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd);
+	if (error)
+		return ERR_PTR(error);
+	res = lookup_create(&nd, is_dir);
+	if (IS_ERR(res)) {
+		mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
+		path_put(&nd.path);
+	}
+	*path = nd.path;
+	return res;
+}
+EXPORT_SYMBOL(kern_path_create);
+
+struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, int is_dir)
+{
+	char *tmp = getname(pathname);
+	struct dentry *res;
+	if (IS_ERR(tmp))
+		return ERR_CAST(tmp);
+	res = kern_path_create(dfd, tmp, path, is_dir);
+	putname(tmp);
+	return res;
+}
+EXPORT_SYMBOL(user_path_create);
+
 int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
 {
 	int error = may_create(dir, dentry);
@@ -2359,54 +2388,46 @@ static int may_mknod(mode_t mode)
 SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode,
 		unsigned, dev)
 {
-	int error;
-	char *tmp;
 	struct dentry *dentry;
-	struct nameidata nd;
+	struct path path;
+	int error;
 
 	if (S_ISDIR(mode))
 		return -EPERM;
 
-	error = user_path_parent(dfd, filename, &nd, &tmp);
-	if (error)
-		return error;
+	dentry = user_path_create(dfd, filename, &path, 0);
+	if (IS_ERR(dentry))
+		return PTR_ERR(dentry);
 
-	dentry = lookup_create(&nd, 0);
-	if (IS_ERR(dentry)) {
-		error = PTR_ERR(dentry);
-		goto out_unlock;
-	}
-	if (!IS_POSIXACL(nd.path.dentry->d_inode))
+	if (!IS_POSIXACL(path.dentry->d_inode))
 		mode &= ~current_umask();
 	error = may_mknod(mode);
 	if (error)
 		goto out_dput;
-	error = mnt_want_write(nd.path.mnt);
+	error = mnt_want_write(path.mnt);
 	if (error)
 		goto out_dput;
-	error = security_path_mknod(&nd.path, dentry, mode, dev);
+	error = security_path_mknod(&path, dentry, mode, dev);
 	if (error)
 		goto out_drop_write;
 	switch (mode & S_IFMT) {
 		case 0: case S_IFREG:
-			error = vfs_create(nd.path.dentry->d_inode,dentry,mode,NULL);
+			error = vfs_create(path.dentry->d_inode,dentry,mode,NULL);
 			break;
 		case S_IFCHR: case S_IFBLK:
-			error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,
+			error = vfs_mknod(path.dentry->d_inode,dentry,mode,
 					new_decode_dev(dev));
 			break;
 		case S_IFIFO: case S_IFSOCK:
-			error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0);
+			error = vfs_mknod(path.dentry->d_inode,dentry,mode,0);
 			break;
 	}
 out_drop_write:
-	mnt_drop_write(nd.path.mnt);
+	mnt_drop_write(path.mnt);
 out_dput:
 	dput(dentry);
-out_unlock:
-	mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
-	path_put(&nd.path);
-	putname(tmp);
+	mutex_unlock(&path.dentry->d_inode->i_mutex);
+	path_put(&path);
 
 	return error;
 }
@@ -2439,38 +2460,29 @@ int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 
 SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode)
 {
-	int error = 0;
-	char * tmp;
 	struct dentry *dentry;
-	struct nameidata nd;
-
-	error = user_path_parent(dfd, pathname, &nd, &tmp);
-	if (error)
-		goto out_err;
+	struct path path;
+	int error;
 
-	dentry = lookup_create(&nd, 1);
-	error = PTR_ERR(dentry);
+	dentry = user_path_create(dfd, pathname, &path, 1);
 	if (IS_ERR(dentry))
-		goto out_unlock;
+		return PTR_ERR(dentry);
 
-	if (!IS_POSIXACL(nd.path.dentry->d_inode))
+	if (!IS_POSIXACL(path.dentry->d_inode))
 		mode &= ~current_umask();
-	error = mnt_want_write(nd.path.mnt);
+	error = mnt_want_write(path.mnt);
 	if (error)
 		goto out_dput;
-	error = security_path_mkdir(&nd.path, dentry, mode);
+	error = security_path_mkdir(&path, dentry, mode);
 	if (error)
 		goto out_drop_write;
-	error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode);
+	error = vfs_mkdir(path.dentry->d_inode, dentry, mode);
 out_drop_write:
-	mnt_drop_write(nd.path.mnt);
+	mnt_drop_write(path.mnt);
 out_dput:
 	dput(dentry);
-out_unlock:
-	mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
-	path_put(&nd.path);
-	putname(tmp);
-out_err:
+	mutex_unlock(&path.dentry->d_inode->i_mutex);
+	path_put(&path);
 	return error;
 }
 
@@ -2730,38 +2742,31 @@ SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
 {
 	int error;
 	char *from;
-	char *to;
 	struct dentry *dentry;
-	struct nameidata nd;
+	struct path path;
 
 	from = getname(oldname);
 	if (IS_ERR(from))
 		return PTR_ERR(from);
 
-	error = user_path_parent(newdfd, newname, &nd, &to);
-	if (error)
-		goto out_putname;
-
-	dentry = lookup_create(&nd, 0);
+	dentry = user_path_create(newdfd, newname, &path, 0);
 	error = PTR_ERR(dentry);
 	if (IS_ERR(dentry))
-		goto out_unlock;
+		goto out_putname;
 
-	error = mnt_want_write(nd.path.mnt);
+	error = mnt_want_write(path.mnt);
 	if (error)
 		goto out_dput;
-	error = security_path_symlink(&nd.path, dentry, from);
+	error = security_path_symlink(&path, dentry, from);
 	if (error)
 		goto out_drop_write;
-	error = vfs_symlink(nd.path.dentry->d_inode, dentry, from);
+	error = vfs_symlink(path.dentry->d_inode, dentry, from);
 out_drop_write:
-	mnt_drop_write(nd.path.mnt);
+	mnt_drop_write(path.mnt);
 out_dput:
 	dput(dentry);
-out_unlock:
-	mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
-	path_put(&nd.path);
-	putname(to);
+	mutex_unlock(&path.dentry->d_inode->i_mutex);
+	path_put(&path);
 out_putname:
 	putname(from);
 	return error;
@@ -2826,11 +2831,9 @@ SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
 		int, newdfd, const char __user *, newname, int, flags)
 {
 	struct dentry *new_dentry;
-	struct nameidata nd;
-	struct path old_path;
+	struct path old_path, new_path;
 	int how = 0;
 	int error;
-	char *to;
 
 	if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0)
 		return -EINVAL;
@@ -2852,32 +2855,27 @@ SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
 	if (error)
 		return error;
 
-	error = user_path_parent(newdfd, newname, &nd, &to);
-	if (error)
-		goto out;
-	error = -EXDEV;
-	if (old_path.mnt != nd.path.mnt)
-		goto out_release;
-	new_dentry = lookup_create(&nd, 0);
+	new_dentry = user_path_create(newdfd, newname, &new_path, 0);
 	error = PTR_ERR(new_dentry);
 	if (IS_ERR(new_dentry))
-		goto out_unlock;
-	error = mnt_want_write(nd.path.mnt);
+		goto out;
+
+	error = -EXDEV;
+	if (old_path.mnt != new_path.mnt)
+		goto out_dput;
+	error = mnt_want_write(new_path.mnt);
 	if (error)
 		goto out_dput;
-	error = security_path_link(old_path.dentry, &nd.path, new_dentry);
+	error = security_path_link(old_path.dentry, &new_path, new_dentry);
 	if (error)
 		goto out_drop_write;
-	error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry);
+	error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry);
 out_drop_write:
-	mnt_drop_write(nd.path.mnt);
+	mnt_drop_write(new_path.mnt);
 out_dput:
 	dput(new_dentry);
-out_unlock:
-	mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
-out_release:
-	path_put(&nd.path);
-	putname(to);
+	mutex_unlock(&new_path.dentry->d_inode->i_mutex);
+	path_put(&new_path);
 out:
 	path_put(&old_path);
 
diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index ebfd382..cf78233 100644
--- a/fs/ocfs2/refcounttree.c
+++ b/fs/ocfs2/refcounttree.c
@@ -4368,25 +4368,6 @@ static inline int ocfs2_may_create(struct inode *dir, struct dentry *child)
 	return inode_permission(dir, MAY_WRITE | MAY_EXEC);
 }
 
-/* copied from user_path_parent. */
-static int ocfs2_user_path_parent(const char __user *path,
-				  struct nameidata *nd, char **name)
-{
-	char *s = getname(path);
-	int error;
-
-	if (IS_ERR(s))
-		return PTR_ERR(s);
-
-	error = kern_path_parent(s, nd);
-	if (error)
-		putname(s);
-	else
-		*name = s;
-
-	return error;
-}
-
 /**
  * ocfs2_vfs_reflink - Create a reference-counted link
  *
@@ -4460,10 +4441,8 @@ int ocfs2_reflink_ioctl(struct inode *inode,
 			bool preserve)
 {
 	struct dentry *new_dentry;
-	struct nameidata nd;
-	struct path old_path;
+	struct path old_path, new_path;
 	int error;
-	char *to = NULL;
 
 	if (!ocfs2_refcount_tree(OCFS2_SB(inode->i_sb)))
 		return -EOPNOTSUPP;
@@ -4474,39 +4453,33 @@ int ocfs2_reflink_ioctl(struct inode *inode,
 		return error;
 	}
 
-	error = ocfs2_user_path_parent(newname, &nd, &to);
-	if (error) {
+	new_dentry = user_path_create(AT_FDCWD, newname, &new_path, 0);
+	error = PTR_ERR(new_dentry);
+	if (IS_ERR(new_dentry)) {
 		mlog_errno(error);
 		goto out;
 	}
 
 	error = -EXDEV;
-	if (old_path.mnt != nd.path.mnt)
-		goto out_release;
-	new_dentry = lookup_create(&nd, 0);
-	error = PTR_ERR(new_dentry);
-	if (IS_ERR(new_dentry)) {
+	if (old_path.mnt != new_path.mnt) {
 		mlog_errno(error);
-		goto out_unlock;
+		goto out_dput;
 	}
 
-	error = mnt_want_write(nd.path.mnt);
+	error = mnt_want_write(new_path.mnt);
 	if (error) {
 		mlog_errno(error);
 		goto out_dput;
 	}
 
 	error = ocfs2_vfs_reflink(old_path.dentry,
-				  nd.path.dentry->d_inode,
+				  new_path.dentry->d_inode,
 				  new_dentry, preserve);
-	mnt_drop_write(nd.path.mnt);
+	mnt_drop_write(new_path.mnt);
 out_dput:
 	dput(new_dentry);
-out_unlock:
-	mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
-out_release:
-	path_put(&nd.path);
-	putname(to);
+	mutex_unlock(&new_path.dentry->d_inode->i_mutex);
+	path_put(&new_path);
 out:
 	path_put(&old_path);
 
diff --git a/include/linux/namei.h b/include/linux/namei.h
index 3439ab8..b8cea80 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -74,6 +74,8 @@ extern int user_path_at(int, const char __user *, unsigned, struct path *);
 
 extern int kern_path(const char *, unsigned, struct path *);
 
+extern struct dentry *kern_path_create(int, const char *, struct path *, int);
+extern struct dentry *user_path_create(int, const char __user *, struct path *, int);
 extern int kern_path_parent(const char *, struct nameidata *);
 extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
 			   const char *, unsigned int, struct nameidata *);
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 0722a25..ec68e1c 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -808,8 +808,9 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
 	struct net *net = sock_net(sk);
 	struct unix_sock *u = unix_sk(sk);
 	struct sockaddr_un *sunaddr = (struct sockaddr_un *)uaddr;
+	char *sun_path = sunaddr->sun_path;
 	struct dentry *dentry = NULL;
-	struct nameidata nd;
+	struct path path;
 	int err;
 	unsigned hash;
 	struct unix_address *addr;
@@ -845,48 +846,44 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
 	addr->hash = hash ^ sk->sk_type;
 	atomic_set(&addr->refcnt, 1);
 
-	if (sunaddr->sun_path[0]) {
+	if (sun_path[0]) {
 		unsigned int mode;
 		err = 0;
 		/*
 		 * Get the parent directory, calculate the hash for last
 		 * component.
 		 */
-		err = kern_path_parent(sunaddr->sun_path, &nd);
-		if (err)
-			goto out_mknod_parent;
-
-		dentry = lookup_create(&nd, 0);
+		dentry = kern_path_create(AT_FDCWD, sun_path, &path, 0);
 		err = PTR_ERR(dentry);
 		if (IS_ERR(dentry))
-			goto out_mknod_unlock;
+			goto out_mknod_parent;
 
 		/*
 		 * All right, let's create it.
 		 */
 		mode = S_IFSOCK |
 		       (SOCK_INODE(sock)->i_mode & ~current_umask());
-		err = mnt_want_write(nd.path.mnt);
+		err = mnt_want_write(path.mnt);
 		if (err)
 			goto out_mknod_dput;
-		err = security_path_mknod(&nd.path, dentry, mode, 0);
+		err = security_path_mknod(&path, dentry, mode, 0);
 		if (err)
 			goto out_mknod_drop_write;
-		err = vfs_mknod(nd.path.dentry->d_inode, dentry, mode, 0);
+		err = vfs_mknod(path.dentry->d_inode, dentry, mode, 0);
 out_mknod_drop_write:
-		mnt_drop_write(nd.path.mnt);
+		mnt_drop_write(path.mnt);
 		if (err)
 			goto out_mknod_dput;
-		mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
-		dput(nd.path.dentry);
-		nd.path.dentry = dentry;
+		mutex_unlock(&path.dentry->d_inode->i_mutex);
+		dput(path.dentry);
+		path.dentry = dentry;
 
 		addr->hash = UNIX_HASH_SIZE;
 	}
 
 	spin_lock(&unix_table_lock);
 
-	if (!sunaddr->sun_path[0]) {
+	if (!sun_path[0]) {
 		err = -EADDRINUSE;
 		if (__unix_find_socket_byname(net, sunaddr, addr_len,
 					      sk->sk_type, hash)) {
@@ -897,8 +894,8 @@ out_mknod_drop_write:
 		list = &unix_socket_table[addr->hash];
 	} else {
 		list = &unix_socket_table[dentry->d_inode->i_ino & (UNIX_HASH_SIZE-1)];
-		u->dentry = nd.path.dentry;
-		u->mnt    = nd.path.mnt;
+		u->dentry = path.dentry;
+		u->mnt    = path.mnt;
 	}
 
 	err = 0;
@@ -915,9 +912,8 @@ out:
 
 out_mknod_dput:
 	dput(dentry);
-out_mknod_unlock:
-	mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
-	path_put(&nd.path);
+	mutex_unlock(&path.dentry->d_inode->i_mutex);
+	path_put(&path);
 out_mknod_parent:
 	if (err == -EEXIST)
 		err = -EADDRINUSE;