netdev - [PATCH net 1/2] net: sched: only keep the available bits when setting vxlan md->gbp

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Message-Id: <6772f33cc49808af9be5c7109d9eed20d309e863.1599997873.git.lucien.xin@gmail.com>
Date:   Sun, 13 Sep 2020 19:51:50 +0800
From:   Xin Long <lucien.xin@...il.com>
To:     network dev <netdev@...r.kernel.org>
Cc:     davem@...emloft.net, Jamal Hadi Salim <jhs@...atatu.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Jiri Pirko <jiri@...nulli.us>
Subject: [PATCH net 1/2] net: sched: only keep the available bits when setting vxlan md->gbp

As we can see from vxlan_build/parse_gbp_hdr(), when processing metadata
on vxlan rx/tx path, only dont_learn/policy_applied/policy_id fields can
be set to or parse from the packet for vxlan gbp option.

So we'd better do the mask when set it in act_tunnel_key and cls_flower.
Otherwise, when users don't know these bits, they may configure with a
value which can never be matched.

Reported-by: Shuang Li <shuali@...hat.com>
Signed-off-by: Xin Long <lucien.xin@...il.com>
---
 include/net/vxlan.h        | 3 +++
 net/sched/act_tunnel_key.c | 1 +
 net/sched/cls_flower.c     | 4 +++-
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/include/net/vxlan.h b/include/net/vxlan.h
index 3a41627c..08537aa 100644
--- a/include/net/vxlan.h
+++ b/include/net/vxlan.h
@@ -121,6 +121,9 @@ struct vxlanhdr_gbp {
 #define VXLAN_GBP_POLICY_APPLIED	(BIT(3) << 16)
 #define VXLAN_GBP_ID_MASK		(0xFFFF)
 
+#define VXLAN_GBP_MASK (VXLAN_GBP_DONT_LEARN | VXLAN_GBP_POLICY_APPLIED | \
+			VXLAN_GBP_ID_MASK)
+
 /*
  * VXLAN Generic Protocol Extension (VXLAN_F_GPE):
  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
diff --git a/net/sched/act_tunnel_key.c b/net/sched/act_tunnel_key.c
index 536c4bc..37f1e10 100644
--- a/net/sched/act_tunnel_key.c
+++ b/net/sched/act_tunnel_key.c
@@ -156,6 +156,7 @@ tunnel_key_copy_vxlan_opt(const struct nlattr *nla, void *dst, int dst_len,
 		struct vxlan_metadata *md = dst;
 
 		md->gbp = nla_get_u32(tb[TCA_TUNNEL_KEY_ENC_OPT_VXLAN_GBP]);
+		md->gbp &= VXLAN_GBP_MASK;
 	}
 
 	return sizeof(struct vxlan_metadata);
diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index 19a8fa2..fed18fd 100644
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -1175,8 +1175,10 @@ static int fl_set_vxlan_opt(const struct nlattr *nla, struct fl_flow_key *key,
 		return -EINVAL;
 	}
 
-	if (tb[TCA_FLOWER_KEY_ENC_OPT_VXLAN_GBP])
+	if (tb[TCA_FLOWER_KEY_ENC_OPT_VXLAN_GBP]) {
 		md->gbp = nla_get_u32(tb[TCA_FLOWER_KEY_ENC_OPT_VXLAN_GBP]);
+		md->gbp &= VXLAN_GBP_MASK;
+	}
 
 	return sizeof(*md);
 }
-- 
2.1.0