In case of modifying an IPv6 packet src/dst address the L4 checksum should be
recalculated only for the first frag. Currently it's done for all frags,
leading to incorrect reassembled packet checksum.
Fix it by adding a new flag to recalculate the checksum only for last frag.
Fixes: bc7a5acdff08 ("datapath: add ipv6 'set' action")
Signed-off-by: Salem Sol <sal...@nvidia.com>
---
lib/packets.c | 12 ++++++++----
tests/system-traffic.at | 35 +++++++++++++++++++++++++++++++++++
2 files changed, 43 insertions(+), 4 deletions(-)
Revision history:
- v3 -> v2: Changed the checksum calculation to be on the first frag
- v2 -> v1: Removed redundant line - Acked-by: Mike Pattrick
<m...@redhat.com>.
Link to passing github actions can be found in [1].
[1]: https://github.com/salemsol/ovs/actions/runs/2455292688
diff --git a/lib/packets.c b/lib/packets.c
index d0fba8176..8f5976bbd 100644
--- a/lib/packets.c
+++ b/lib/packets.c
@@ -1153,7 +1153,7 @@ packet_set_ipv4_addr(struct dp_packet *packet,
*
* This function assumes that L3 and L4 offsets are set in the packet. */
static bool
-packet_rh_present(struct dp_packet *packet, uint8_t *nexthdr)
+packet_rh_present(struct dp_packet *packet, uint8_t *nexthdr, bool *first_frag)
{
const struct ovs_16aligned_ip6_hdr *nh;
size_t len;
@@ -1203,6 +1203,8 @@ packet_rh_present(struct dp_packet *packet, uint8_t
*nexthdr)
const struct ovs_16aligned_ip6_frag *frag_hdr
= ALIGNED_CAST(struct ovs_16aligned_ip6_frag *, data);
+ *first_frag = !(frag_hdr->ip6f_offlg & IP6F_OFF_MASK) &&
+ (frag_hdr->ip6f_offlg & IP6F_MORE_FRAG);
*nexthdr = frag_hdr->ip6f_nxt;
len = sizeof *frag_hdr;
} else if (*nexthdr == IPPROTO_ROUTING) {
@@ -1333,18 +1335,20 @@ packet_set_ipv6(struct dp_packet *packet, const struct
in6_addr *src,
uint8_t key_hl)
{
struct ovs_16aligned_ip6_hdr *nh = dp_packet_l3(packet);
+ bool recalc_csum = true;
uint8_t proto = 0;
bool rh_present;
- rh_present = packet_rh_present(packet, &proto);
+ rh_present = packet_rh_present(packet, &proto, &recalc_csum);
if (memcmp(&nh->ip6_src, src, sizeof(ovs_be32[4]))) {
- packet_set_ipv6_addr(packet, proto, nh->ip6_src.be32, src, true);
+ packet_set_ipv6_addr(packet, proto, nh->ip6_src.be32,
+ src, recalc_csum);
}
if (memcmp(&nh->ip6_dst, dst, sizeof(ovs_be32[4]))) {
packet_set_ipv6_addr(packet, proto, nh->ip6_dst.be32, dst,
- !rh_present);
+ !rh_present && recalc_csum);
}
packet_set_ipv6_tc(&nh->ip6_flow, key_tc);
diff --git a/tests/system-traffic.at b/tests/system-traffic.at
index 239105e89..588e1b2e2 100644
--- a/tests/system-traffic.at
+++ b/tests/system-traffic.at
@@ -192,6 +192,41 @@ NS_CHECK_EXEC([at_ns0], [ping6 -s 3200 -q -c 3 -i 0.3 -w 2
fc00:1::2 | FORMAT_PI
OVS_TRAFFIC_VSWITCHD_STOP
AT_CLEANUP
+AT_SETUP([datapath - ping6 between two ports with header modify])
+OVS_TRAFFIC_VSWITCHD_START()
+
+AT_CHECK([ovs-ofctl add-flow br0 "actions=normal"])
+
+ADD_NAMESPACES(at_ns0, at_ns1)
+
+ADD_VETH(p0, at_ns0, br0, "fc00::1/96", e4:11:22:33:44:55)
+ADD_VETH(p1, at_ns1, br0, "fc00::2/96", e4:11:22:33:44:54)
+NS_CHECK_EXEC([at_ns0], [ip -6 neigh add fc00::3 lladdr e4:11:22:33:44:54 dev
p0])
+NS_CHECK_EXEC([at_ns0], [ip -6 neigh add fc00::2 lladdr e4:11:22:33:44:54 dev
p0])
+NS_CHECK_EXEC([at_ns0], [ip -6 neigh add fc00::1 lladdr e4:11:22:33:44:55 dev
p0])
+
+dnl Linux seems to take a little time to get its IPv6 stack in order. Without
+dnl waiting, we get occasional failures due to the following error:
+dnl "connect: Cannot assign requested address"
+OVS_WAIT_UNTIL([ip netns exec at_ns0 ping6 -c 1 fc00::2])
+
+AT_CHECK([ovs-ofctl del-flows -OOpenFlow15 br0])
+AT_CHECK([ovs-ofctl add-flow -OOpenFlow15 br0
in_port=ovs-p0,ipv6,ipv6_dst=fc00::3,ipv6_src=fc00::1,actions=set_field:fc00::2-\>ipv6_dst,ovs-p1])
+AT_CHECK([ovs-ofctl add-flow -OOpenFlow15 br0
in_port=ovs-p1,ipv6,ipv6_dst=fc00::1,ipv6_src=fc00::2,actions=set_field:fc00::3-\>ipv6_src,ovs-p0])
+
+NS_CHECK_EXEC([at_ns0], [ping6 -q -c 3 -i 0.3 -w 2 fc00::3 | FORMAT_PING],
[0], [dnl
+3 packets transmitted, 3 received, 0% packet loss, time 0ms
+])
+NS_CHECK_EXEC([at_ns0], [ping6 -s 1600 -q -c 3 -i 0.3 -w 2 fc00::3 |
FORMAT_PING], [0], [dnl
+3 packets transmitted, 3 received, 0% packet loss, time 0ms
+])
+NS_CHECK_EXEC([at_ns0], [ping6 -s 3200 -q -c 3 -i 0.3 -w 2 fc00::3 |
FORMAT_PING], [0], [dnl
+3 packets transmitted, 3 received, 0% packet loss, time 0ms
+])
+
+OVS_TRAFFIC_VSWITCHD_STOP
+AT_CLEANUP
+
AT_SETUP([datapath - ping over bond])
OVS_TRAFFIC_VSWITCHD_START()
--
2.21.0
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