net/sched: flower: fix parsing of ethertype following VLAN header

[ Upstream commit 2105f700b53c24aa48b65c15652acc386044d26a ]

A tc flower filter matching TCA_FLOWER_KEY_VLAN_ETH_TYPE is expected to
match the L2 ethertype following the first VLAN header, as confirmed by
linked discussion with the maintainer. However, such rule also matches
packets that have additional second VLAN header, even though filter has
both eth_type and vlan_ethtype set to "ipv4". Looking at the code this
seems to be mostly an artifact of the way flower uses flow dissector.
First, even though looking at the uAPI eth_type and vlan_ethtype appear
like a distinct fields, in flower they are all mapped to the same
key->basic.n_proto. Second, flow dissector skips following VLAN header as
no keys for FLOW_DISSECTOR_KEY_CVLAN are set and eventually assigns the
value of n_proto to last parsed header. With these, such filters ignore any
headers present between first VLAN header and first "non magic"
header (ipv4 in this case) that doesn't result
FLOW_DISSECT_RET_PROTO_AGAIN.

Fix the issue by extending flow dissector VLAN key structure with new
'vlan_eth_type' field that matches first ethertype following previously
parsed VLAN header. Modify flower classifier to set the new
flow_dissector_key_vlan->vlan_eth_type with value obtained from
TCA_FLOWER_KEY_VLAN_ETH_TYPE/TCA_FLOWER_KEY_CVLAN_ETH_TYPE uAPIs.

Link: https://lore.kernel.org/all/Yjhgi48BpTGh6dig@nanopsycho/
Fixes: 9399ae9a6cb2 ("net_sched: flower: Add vlan support")
Fixes: d64efd0926ba ("net/sched: flower: Add supprt for matching on QinQ vlan headers")
Signed-off-by: Vlad Buslov <vladbu@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h
index 78f6437cbc3a8b43b0484d5cadf562f13a3f7aba..02171416c68eb7c7e9a1bf3940f9ec374a3c02d0 100644 (file)
--- a/include/net/flow_dissector.h
+++ b/include/net/flow_dissector.h
@@ -51,6 +51,8 @@ struct flow_dissector_key_vlan {
                vlan_dei:1,
                vlan_priority:3;
        __be16  vlan_tpid;
+       __be16  vlan_eth_type;
+       u16     padding;
 };
 
 struct flow_dissector_key_mpls {

diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index b740a74f06f223bb1124e8d90ca6a97cfca0b8a7..4dac27c98623141d72c8bd97e8c7c1bb283745fd 100644 (file)
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -1149,6 +1149,7 @@ proto_again:
                                         VLAN_PRIO_MASK) >> VLAN_PRIO_SHIFT;
                        }
                        key_vlan->vlan_tpid = saved_vlan_tpid;
+                       key_vlan->vlan_eth_type = proto;
                }
 
                fdret = FLOW_DISSECT_RET_PROTO_AGAIN;

diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index 26979b4853bdba408ccf8cc964078f90dfdac64f..007fbc1993522301ebbb70d669a3071d31b57268 100644 (file)
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -784,6 +784,7 @@ static int fl_set_key_mpls(struct nlattr **tb,
 static void fl_set_key_vlan(struct nlattr **tb,
                            __be16 ethertype,
                            int vlan_id_key, int vlan_prio_key,
+                           int vlan_next_eth_type_key,
                            struct flow_dissector_key_vlan *key_val,
                            struct flow_dissector_key_vlan *key_mask)
 {
@@ -802,6 +803,11 @@ static void fl_set_key_vlan(struct nlattr **tb,
        }
        key_val->vlan_tpid = ethertype;
        key_mask->vlan_tpid = cpu_to_be16(~0);
+       if (tb[vlan_next_eth_type_key]) {
+               key_val->vlan_eth_type =
+                       nla_get_be16(tb[vlan_next_eth_type_key]);
+               key_mask->vlan_eth_type = cpu_to_be16(~0);
+       }
 }
 
 static void fl_set_key_flag(u32 flower_key, u32 flower_mask,
@@ -1076,8 +1082,9 @@ static int fl_set_key(struct net *net, struct nlattr **tb,
 
                if (eth_type_vlan(ethertype)) {
                        fl_set_key_vlan(tb, ethertype, TCA_FLOWER_KEY_VLAN_ID,
-                                       TCA_FLOWER_KEY_VLAN_PRIO, &key->vlan,
-                                       &mask->vlan);
+                                       TCA_FLOWER_KEY_VLAN_PRIO,
+                                       TCA_FLOWER_KEY_VLAN_ETH_TYPE,
+                                       &key->vlan, &mask->vlan);
 
                        if (tb[TCA_FLOWER_KEY_VLAN_ETH_TYPE]) {
                                ethertype = nla_get_be16(tb[TCA_FLOWER_KEY_VLAN_ETH_TYPE]);
@@ -1085,6 +1092,7 @@ static int fl_set_key(struct net *net, struct nlattr **tb,
                                        fl_set_key_vlan(tb, ethertype,
                                                        TCA_FLOWER_KEY_CVLAN_ID,
                                                        TCA_FLOWER_KEY_CVLAN_PRIO,
+                                                       TCA_FLOWER_KEY_CVLAN_ETH_TYPE,
                                                        &key->cvlan, &mask->cvlan);
                                        fl_set_key_val(tb, &key->basic.n_proto,
                                                       TCA_FLOWER_KEY_CVLAN_ETH_TYPE,
@@ -2272,13 +2280,13 @@ static int fl_dump_key(struct sk_buff *skb, struct net *net,
                goto nla_put_failure;
 
        if (mask->basic.n_proto) {
-               if (mask->cvlan.vlan_tpid) {
+               if (mask->cvlan.vlan_eth_type) {
                        if (nla_put_be16(skb, TCA_FLOWER_KEY_CVLAN_ETH_TYPE,
                                         key->basic.n_proto))
                                goto nla_put_failure;
-               } else if (mask->vlan.vlan_tpid) {
+               } else if (mask->vlan.vlan_eth_type) {
                        if (nla_put_be16(skb, TCA_FLOWER_KEY_VLAN_ETH_TYPE,
-                                        key->basic.n_proto))
+                                        key->vlan.vlan_eth_type))
                                goto nla_put_failure;
                }
        }