[PATCH 5.11 530/601] netfilter: nftables_offload: special ethertype handling for VLAN

Greg Kroah-Hartman
2021-05-12T17:56:43Z

From: Pablo Neira Ayuso <pablo@netfilter.org>

[ Upstream commit 783003f3bb8a565326e89d18bbd948ad8ffc816a ]

The nftables offload parser sets FLOW_DISSECTOR_KEY_BASIC .n_proto to the
ethertype field in the ethertype frame. However:

- FLOW_DISSECTOR_KEY_BASIC .n_proto field always stores either IPv4 or IPv6
ethertypes.
- FLOW_DISSECTOR_KEY_VLAN .vlan_tpid stores either the 802.1q and 802.1ad
ethertypes. Same as for FLOW_DISSECTOR_KEY_CVLAN.

This function adjusts the flow dissector to handle two scenarios:

1) FLOW_DISSECTOR_KEY_VLAN .vlan_tpid is set to 802.1q or 802.1ad.
Then, transfer:
- the .n_proto field to FLOW_DISSECTOR_KEY_VLAN .tpid.
- the original FLOW_DISSECTOR_KEY_VLAN .tpid to the
FLOW_DISSECTOR_KEY_CVLAN .tpid
- the original FLOW_DISSECTOR_KEY_CVLAN .tpid to the .n_proto field.

2) .n_proto is set to 802.1q or 802.1ad. Then, transfer:
- the .n_proto field to FLOW_DISSECTOR_KEY_VLAN .tpid.
- the original FLOW_DISSECTOR_KEY_VLAN .tpid to the .n_proto field.

Fixes: a82055af5959 ("netfilter: nft_payload: add VLAN offload support")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/netfilter/nf_tables_offload.c | 44 +++++++++++++++++++++++++++++++
1 file changed, 44 insertions(+)

diff --git a/net/netfilter/nf_tables_offload.c b/net/netfilter/nf_tables_offload.c
index 9ae14270c543..2b00f7f47693 100644
--- a/net/netfilter/nf_tables_offload.c
+++ b/net/netfilter/nf_tables_offload.c
@@ -45,6 +45,48 @@ void nft_flow_rule_set_addr_type(struct nft_flow_rule *flow,
offsetof(struct nft_flow_key, control);
}

+struct nft_offload_ethertype {
+ __be16 value;
+ __be16 mask;
+};
+
+static void nft_flow_rule_transfer_vlan(struct nft_offload_ctx *ctx,
+ struct nft_flow_rule *flow)
+{
+ struct nft_flow_match *match = &flow->match;
+ struct nft_offload_ethertype ethertype;
+
+ if (match->dissector.used_keys & BIT(FLOW_DISSECTOR_KEY_CONTROL) &&
+ match->key.basic.n_proto != htons(ETH_P_8021Q) &&
+ match->key.basic.n_proto != htons(ETH_P_8021AD))
+ return;
+
+ ethertype.value = match->key.basic.n_proto;
+ ethertype.mask = match->mask.basic.n_proto;
+
+ if (match->dissector.used_keys & BIT(FLOW_DISSECTOR_KEY_VLAN) &&
+ (match->key.vlan.vlan_tpid == htons(ETH_P_8021Q) ||
+ match->key.vlan.vlan_tpid == htons(ETH_P_8021AD))) {
+ match->key.basic.n_proto = match->key.cvlan.vlan_tpid;
+ match->mask.basic.n_proto = match->mask.cvlan.vlan_tpid;
+ match->key.cvlan.vlan_tpid = match->key.vlan.vlan_tpid;
+ match->mask.cvlan.vlan_tpid = match->mask.vlan.vlan_tpid;
+ match->key.vlan.vlan_tpid = ethertype.value;
+ match->mask.vlan.vlan_tpid = ethertype.mask;
+ match->dissector.offset[FLOW_DISSECTOR_KEY_CVLAN] =
+ offsetof(struct nft_flow_key, cvlan);
+ match->dissector.used_keys |= BIT(FLOW_DISSECTOR_KEY_CVLAN);
+ } else {
+ match->key.basic.n_proto = match->key.vlan.vlan_tpid;
+ match->mask.basic.n_proto = match->mask.vlan.vlan_tpid;
+ match->key.vlan.vlan_tpid = ethertype.value;
+ match->mask.vlan.vlan_tpid = ethertype.mask;
+ match->dissector.offset[FLOW_DISSECTOR_KEY_VLAN] =
+ offsetof(struct nft_flow_key, vlan);
+ match->dissector.used_keys |= BIT(FLOW_DISSECTOR_KEY_VLAN);
+ }
+}
+
struct nft_flow_rule *nft_flow_rule_create(struct net *net,
const struct nft_rule *rule)
{
@@ -89,6 +131,8 @@ struct nft_flow_rule *nft_flow_rule_create(struct net *net,

expr = nft_expr_next(expr);
}
+ nft_flow_rule_transfer_vlan(ctx, flow);
+
flow->proto = ctx->dep.l3num;
kfree(ctx);

--
2.30.2