allow build_open_flags() to return an error

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

fs/exec.c

@@ -110,13 +110,14 @@ SYSCALL_DEFINE1(uselib, const char __user *, library)
 	static const struct open_flags uselib_flags = {
 		.open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
 		.acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN,
-		.intent = LOOKUP_OPEN
+		.intent = LOOKUP_OPEN,
+		.lookup_flags = LOOKUP_FOLLOW,
 	};
 
 	if (IS_ERR(tmp))
 		goto out;
 
-	file = do_filp_open(AT_FDCWD, tmp, &uselib_flags, LOOKUP_FOLLOW);
+	file = do_filp_open(AT_FDCWD, tmp, &uselib_flags);
 	putname(tmp);
 	error = PTR_ERR(file);
 	if (IS_ERR(file))
@@ -756,10 +757,11 @@ struct file *open_exec(const char *name)
 	static const struct open_flags open_exec_flags = {
 		.open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
 		.acc_mode = MAY_EXEC | MAY_OPEN,
-		.intent = LOOKUP_OPEN
+		.intent = LOOKUP_OPEN,
+		.lookup_flags = LOOKUP_FOLLOW,
 	};
 
-	file = do_filp_open(AT_FDCWD, &tmp, &open_exec_flags, LOOKUP_FOLLOW);
+	file = do_filp_open(AT_FDCWD, &tmp, &open_exec_flags);
 	if (IS_ERR(file))
 		goto out;
 

fs/internal.h

@@ -96,11 +96,12 @@ struct open_flags {
 	umode_t mode;
 	int acc_mode;
 	int intent;
+	int lookup_flags;
 };
 extern struct file *do_filp_open(int dfd, struct filename *pathname,
-		const struct open_flags *op, int flags);
+		const struct open_flags *op);
 extern struct file *do_file_open_root(struct dentry *, struct vfsmount *,
-		const char *, const struct open_flags *, int lookup_flags);
+		const char *, const struct open_flags *);
 
 extern long do_handle_open(int mountdirfd,
 			   struct file_handle __user *ufh, int open_flag);

fs/namei.c

@@ -2969,9 +2969,10 @@ static struct file *path_openat(int dfd, struct filename *pathname,
 }
 
 struct file *do_filp_open(int dfd, struct filename *pathname,
-		const struct open_flags *op, int flags)
+		const struct open_flags *op)
 {
 	struct nameidata nd;
+	int flags = op->lookup_flags;
 	struct file *filp;
 
 	filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU);
@@ -2983,17 +2984,16 @@ struct file *do_filp_open(int dfd, struct filename *pathname,
 }
 
 struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt,
-		const char *name, const struct open_flags *op, int flags)
+		const char *name, const struct open_flags *op)
 {
 	struct nameidata nd;
 	struct file *file;
 	struct filename filename = { .name = name };
+	int flags = op->lookup_flags | LOOKUP_ROOT;
 
 	nd.root.mnt = mnt;
 	nd.root.dentry = dentry;
 
-	flags |= LOOKUP_ROOT;
-
 	if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN)
 		return ERR_PTR(-ELOOP);
 

fs/open.c

@@ -876,7 +876,8 @@ static inline int build_open_flags(int flags, umode_t mode, struct open_flags *o
 		lookup_flags |= LOOKUP_DIRECTORY;
 	if (!(flags & O_NOFOLLOW))
 		lookup_flags |= LOOKUP_FOLLOW;
-	return lookup_flags;
+	op->lookup_flags = lookup_flags;
+	return 0;
 }
 
 /**
@@ -893,8 +894,8 @@ static inline int build_open_flags(int flags, umode_t mode, struct open_flags *o
 struct file *file_open_name(struct filename *name, int flags, umode_t mode)
 {
 	struct open_flags op;
-	int lookup = build_open_flags(flags, mode, &op);
-	return do_filp_open(AT_FDCWD, name, &op, lookup);
+	int err = build_open_flags(flags, mode, &op);
+	return err ? ERR_PTR(err) : do_filp_open(AT_FDCWD, name, &op);
 }
 
 /**
@@ -919,37 +920,43 @@ struct file *file_open_root(struct dentry *dentry, struct vfsmount *mnt,
 			    const char *filename, int flags)
 {
 	struct open_flags op;
-	int lookup = build_open_flags(flags, 0, &op);
+	int err = build_open_flags(flags, 0, &op);
+	if (err)
+		return ERR_PTR(err);
 	if (flags & O_CREAT)
 		return ERR_PTR(-EINVAL);
 	if (!filename && (flags & O_DIRECTORY))
 		if (!dentry->d_inode->i_op->lookup)
 			return ERR_PTR(-ENOTDIR);
-	return do_file_open_root(dentry, mnt, filename, &op, lookup);
+	return do_file_open_root(dentry, mnt, filename, &op);
 }
 EXPORT_SYMBOL(file_open_root);
 
 long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
 {
 	struct open_flags op;
-	int lookup = build_open_flags(flags, mode, &op);
-	struct filename *tmp = getname(filename);
-	int fd = PTR_ERR(tmp);
-
-	if (!IS_ERR(tmp)) {
-		fd = get_unused_fd_flags(flags);
-		if (fd >= 0) {
-			struct file *f = do_filp_open(dfd, tmp, &op, lookup);
-			if (IS_ERR(f)) {
-				put_unused_fd(fd);
-				fd = PTR_ERR(f);
-			} else {
-				fsnotify_open(f);
-				fd_install(fd, f);
-			}
+	int fd = build_open_flags(flags, mode, &op);
+	struct filename *tmp;
+
+	if (fd)
+		return fd;
+
+	tmp = getname(filename);
+	if (IS_ERR(tmp))
+		return PTR_ERR(tmp);
+
+	fd = get_unused_fd_flags(flags);
+	if (fd >= 0) {
+		struct file *f = do_filp_open(dfd, tmp, &op);
+		if (IS_ERR(f)) {
+			put_unused_fd(fd);
+			fd = PTR_ERR(f);
+		} else {
+			fsnotify_open(f);
+			fd_install(fd, f);
 		}
-		putname(tmp);
 	}
+	putname(tmp);
 	return fd;
 }