[PATCH 1/4] listmount: rip out flags

[Miklos Szeredi <mszeredi@xxxxxxxxxx>]

LISTMOUNT_UNREACHABLE will be achieved differently in a following patch.

LISTMOUNT_RECURSIVE becomes the default.  If non-recursive listing turns
out to be needed, it can be added later.

Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
---
 fs/namespace.c             | 49 +++++++++++++-------------------------
 include/uapi/linux/mount.h |  4 ----
 2 files changed, 16 insertions(+), 37 deletions(-)

diff --git a/fs/namespace.c b/fs/namespace.c
index cb338ab18db9..9b4cb25c25ed 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -5004,18 +5004,13 @@ static struct mount *listmnt_first(struct mount *root)
 	return list_first_entry_or_null(&root->mnt_mounts, struct mount, mnt_child);
 }
 
-static struct mount *listmnt_next(struct mount *curr, struct mount *root, bool recurse)
+static struct mount *listmnt_next(struct mount *curr, struct mount *root)
 {
-	if (recurse)
-		return next_mnt(curr, root);
-	if (!list_is_head(curr->mnt_child.next, &root->mnt_mounts))
-		return list_next_entry(curr, mnt_child);
-	return NULL;
+	return next_mnt(curr, root);
 }
 
 static ssize_t do_listmount(struct vfsmount *mnt, u64 __user *buf,
-			    size_t bufsize, const struct path *root,
-			    unsigned int flags)
+			    size_t bufsize, const struct path *root)
 {
 	struct mount *r, *m = real_mount(mnt);
 	struct path rootmnt = {
@@ -5023,26 +5018,17 @@ static ssize_t do_listmount(struct vfsmount *mnt, u64 __user *buf,
 		.dentry = root->mnt->mnt_root
 	};
 	ssize_t ctr;
-	bool reachable_only = true;
-	bool recurse = flags & LISTMOUNT_RECURSIVE;
 	int err;
 
-	if (flags & LISTMOUNT_UNREACHABLE) {
-		if (!capable(CAP_SYS_ADMIN))
-			return -EPERM;
-		reachable_only = false;
-	}
-
-	if (reachable_only && !is_path_reachable(m, mnt->mnt_root, &rootmnt))
+	if (!is_path_reachable(m, mnt->mnt_root, &rootmnt))
 		return capable(CAP_SYS_ADMIN) ? 0 : -EPERM;
 
 	err = security_sb_statfs(mnt->mnt_root);
 	if (err)
 		return err;
 
-	for (ctr = 0, r = listmnt_first(m); r; r = listmnt_next(r, m, recurse)) {
-		if (reachable_only &&
-		    !is_path_reachable(r, r->mnt.mnt_root, root))
+	for (ctr = 0, r = listmnt_first(m); r; r = listmnt_next(r, m)) {
+		if (!is_path_reachable(r, r->mnt.mnt_root, root))
 			continue;
 
 		if (ctr >= bufsize)
@@ -5065,7 +5051,7 @@ SYSCALL_DEFINE4(listmount, const struct mnt_id_req __user *, req,
 	u64 mnt_id;
 	ssize_t ret;
 
-	if (flags & ~(LISTMOUNT_UNREACHABLE | LISTMOUNT_RECURSIVE))
+	if (flags)
 		return -EINVAL;
 
 	if (copy_from_user(&kreq, req, sizeof(kreq)))
@@ -5075,20 +5061,17 @@ SYSCALL_DEFINE4(listmount, const struct mnt_id_req __user *, req,
 	mnt_id = kreq.mnt_id;
 
 	down_read(&namespace_sem);
-	if (mnt_id == LSMT_ROOT)
-		mnt = &current->nsproxy->mnt_ns->root->mnt;
-	else
-		mnt = lookup_mnt_in_ns(mnt_id, current->nsproxy->mnt_ns);
-	if (!mnt) {
-		up_read(&namespace_sem);
-		return -ENOENT;
-	}
-
 	get_fs_root(current->fs, &root);
-	/* Skip unreachable for LSMT_ROOT */
-	if (mnt_id == LSMT_ROOT && !(flags & LISTMOUNT_UNREACHABLE))
+	if (mnt_id == LSMT_ROOT) {
 		mnt = root.mnt;
-	ret = do_listmount(mnt, buf, bufsize, &root, flags);
+	} else {
+		ret = -ENOENT;
+		mnt = lookup_mnt_in_ns(mnt_id, current->nsproxy->mnt_ns);
+		if (!mnt)
+			goto err;
+	}
+	ret = do_listmount(mnt, buf, bufsize, &root);
+err:
 	path_put(&root);
 	up_read(&namespace_sem);
 	return ret;
diff --git a/include/uapi/linux/mount.h b/include/uapi/linux/mount.h
index 7a5bd0b24a62..f6b35a15b7dd 100644
--- a/include/uapi/linux/mount.h
+++ b/include/uapi/linux/mount.h
@@ -191,10 +191,6 @@ struct mnt_id_req {
 #define STATMOUNT_MNT_POINT		0x00000010U	/* Want/got mnt_point */
 #define STATMOUNT_FS_TYPE		0x00000020U	/* Want/got fs_type */
 
-/* listmount(2) flags */
-#define LISTMOUNT_UNREACHABLE	0x01U	/* List unreachable mounts too */
-#define LISTMOUNT_RECURSIVE	0x02U	/* List a mount tree */
-
 /*
  * Special @mnt_id values that can be passed to listmount
  */
-- 
2.41.0