[PATCH] l2_packet: Enable receiving priority tagged (VID 0) frames

[R. Christian McDonald]

Certain internet service providers transmit vlan 0 priority tagged
EAPOL frames from the ONT towards the residential gateway. VID 0
should be ignored, and the frame processed according to the priority
set in the 802.1P bits and the encapsulated EtherType (i.e. EAPOL).

The pcap filter utilized by l2_packet is inadquate for this use case.

Here we modify the pcap filter to accept both unencapsulated and
encapsulated (with VLAN 0) EAPOL EtherTypes. This preserves the
original filter behavior while also matching on encapsulated EAPOL.

Signed-off-by: R. Christian McDonald <rcm at rcm.sh>
Sponsored by: Rubicon Communications, LLC ("Netgate")
---
 src/l2_packet/l2_packet_freebsd.c | 4 ++--
 src/l2_packet/l2_packet_pcap.c    | 4 ++--
 src/l2_packet/l2_packet_winpcap.c | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/l2_packet/l2_packet_freebsd.c b/src/l2_packet/l2_packet_freebsd.c
index 60de9fe6b..cefcc0545 100644
--- a/src/l2_packet/l2_packet_freebsd.c
+++ b/src/l2_packet/l2_packet_freebsd.c
@@ -122,10 +122,10 @@ static int l2_packet_init_libpcap(struct l2_packet_data *l2,
 	os_snprintf(pcap_filter, sizeof(pcap_filter),
 		    "not ether src " MACSTR " and "
 		    "( ether dst " MACSTR " or ether dst " MACSTR " ) and "
-		    "ether proto 0x%x",
+		    "( ether proto 0x%x or ( vlan 0 and ether proto 0x%x ) )",
 		    MAC2STR(l2->own_addr), /* do not receive own packets */
 		    MAC2STR(l2->own_addr), MAC2STR(pae_group_addr),
-		    protocol);
+		    protocol, protocol);
 	if (pcap_compile(l2->pcap, &pcap_fp, pcap_filter, 1, pcap_netp) < 0) {
 		fprintf(stderr, "pcap_compile: %s\n", pcap_geterr(l2->pcap));
 		return -1;
diff --git a/src/l2_packet/l2_packet_pcap.c b/src/l2_packet/l2_packet_pcap.c
index c2b17fcf8..e05be9902 100644
--- a/src/l2_packet/l2_packet_pcap.c
+++ b/src/l2_packet/l2_packet_pcap.c
@@ -232,10 +232,10 @@ static int l2_packet_init_libpcap(struct l2_packet_data *l2,
 	os_snprintf(pcap_filter, sizeof(pcap_filter),
 		    "not ether src " MACSTR " and "
 		    "( ether dst " MACSTR " or ether dst " MACSTR " ) and "
-		    "ether proto 0x%x",
+		    "( ether proto 0x%x or ( vlan 0 and ether proto 0x%x) )",
 		    MAC2STR(l2->own_addr), /* do not receive own packets */
 		    MAC2STR(l2->own_addr), MAC2STR(pae_group_addr),
-		    protocol);
+		    protocol, protocol);
 	if (pcap_compile(l2->pcap, &pcap_fp, pcap_filter, 1, pcap_netp) < 0) {
 		fprintf(stderr, "pcap_compile: %s\n", pcap_geterr(l2->pcap));
 		return -1;
diff --git a/src/l2_packet/l2_packet_winpcap.c b/src/l2_packet/l2_packet_winpcap.c
index 3452051f5..14ef85655 100644
--- a/src/l2_packet/l2_packet_winpcap.c
+++ b/src/l2_packet/l2_packet_winpcap.c
@@ -175,10 +175,10 @@ static int l2_packet_init_libpcap(struct l2_packet_data *l2,
 	os_snprintf(pcap_filter, sizeof(pcap_filter),
 		    "not ether src " MACSTR " and "
 		    "( ether dst " MACSTR " or ether dst " MACSTR " ) and "
-		    "ether proto 0x%x",
+		    "( ether proto 0x%x or ( vlan 0 and ether proto 0x%x ) )",
 		    MAC2STR(l2->own_addr), /* do not receive own packets */
 		    MAC2STR(l2->own_addr), MAC2STR(pae_group_addr),
-		    protocol);
+		    protocol, protocol);
 	if (pcap_compile(l2->pcap, &pcap_fp, pcap_filter, 1, pcap_netp) < 0) {
 		fprintf(stderr, "pcap_compile: %s\n", pcap_geterr(l2->pcap));
 		return -1;
-- 
2.41.0