LSM: lift extracting and parsing LSM options into the caller of ->sb_remount()

This paves the way for retaining the LSM options from a common filesystem
mount context during a mount parameter parsing phase to be instituted prior
to actual mount/reconfiguration actions.

Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 18 insertions, 1 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index 08cffdad6665..341793fbd390 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2299,6 +2299,7 @@ static int do_remount(struct path *path, int ms_flags, int sb_flags,
 	int err;
 	struct super_block *sb = path->mnt->mnt_sb;
 	struct mount *mnt = real_mount(path->mnt);
+	struct security_mnt_opts opts;
 
 	if (!check_mnt(mnt))
 		return -EINVAL;
@@ -2309,7 +2310,23 @@ static int do_remount(struct path *path, int ms_flags, int sb_flags,
 	if (!can_change_locked_flags(mnt, mnt_flags))
 		return -EPERM;
 
-	err = security_sb_remount(sb, data);
+	security_init_mnt_opts(&opts);
+	if (data && !(sb->s_type->fs_flags & FS_BINARY_MOUNTDATA)) {
+		char *secdata = alloc_secdata();
+		if (!secdata)
+			return -ENOMEM;
+		err = security_sb_copy_data(data, secdata);
+		if (err) {
+			free_secdata(secdata);
+			return err;
+		}
+		err = security_sb_parse_opts_str(secdata, &opts);
+		free_secdata(secdata);
+		if (err)
+			return err;
+	}
+	err = security_sb_remount(sb, &opts);
+	security_free_mnt_opts(&opts);
 	if (err)
 		return err;