[PATCH nf-next] netfilter: xt_owner: bail out with EINVAL in case of unsupported flags

[PATCH nf-next] netfilter: xt_owner: bail out with EINVAL in case of unsupported flags

[Pablo Neira Ayuso]

Reject flags that are not supported with EINVAL.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
A bit late for ea6cc2fd8a2b ("netfilter: xt_owner: Add supplementary
groups option"). Old kernel will ignore this new flag, so better bail
out for future flags. We can also request a backport to be send to
-stable kernels to deal with this new supplementary group support.
Otherwise, we have to go for a new revision.

 include/uapi/linux/netfilter/xt_owner.h | 5 +++++
 net/netfilter/xt_owner.c                | 3 +++
 2 files changed, 8 insertions(+)

diff --git a/include/uapi/linux/netfilter/xt_owner.h b/include/uapi/linux/netfilter/xt_owner.h
index 9e98c09eda32..5108df4d0313 100644
--- a/include/uapi/linux/netfilter/xt_owner.h
+++ b/include/uapi/linux/netfilter/xt_owner.h
@@ -11,6 +11,11 @@ enum {
 	XT_OWNER_SUPPL_GROUPS = 1 << 3,
 };
 
+#define XT_OWNER_MASK	(XT_OWNER_UID | 	\
+			 XT_OWNER_GID | 	\
+			 XT_OWNER_SOCKET |	\
+			 XT_OWNER_SUPPL_GROUPS)
+
 struct xt_owner_match_info {
 	__u32 uid_min, uid_max;
 	__u32 gid_min, gid_max;
diff --git a/net/netfilter/xt_owner.c b/net/netfilter/xt_owner.c
index a8784502aca6..ee597fdc5db7 100644
--- a/net/netfilter/xt_owner.c
+++ b/net/netfilter/xt_owner.c
@@ -25,6 +25,9 @@ static int owner_check(const struct xt_mtchk_param *par)
 	struct xt_owner_match_info *info = par->matchinfo;
 	struct net *net = par->net;
 
+	if (info->match & ~XT_OWNER_MASK)
+		return -EINVAL;
+
 	/* Only allow the common case where the userns of the writer
 	 * matches the userns of the network namespace.
 	 */
-- 
2.11.0