We forward the incoming MAC address through the tap interface when
receiving incoming packets from network local hosts.
This is a part of the solution to bug
https://bugs.passt.top/show_bug.cgi?id=120
Signed-off-by: Jon Maloy
Reviewed-by: David Gibson
---
v3: - Adapted to the move of external MAC address from struct flowside
to struct flow_common
v4: - Changed signature of udp_tap_prepare() to take a MAC address
instead of a flow.
- Eliminated initialization of MAC source address in all frames,
since those now are set per send occasion anyway.
v5: - Added lookup in ARP/NDP table on incoming messages in
case flow->tap_omac wasn't initialized at flow creation,
i.e., the flow was initiated from the guest.
v6: - Using MAC_ZERO
---
passt.c | 2 +-
udp.c | 45 +++++++++++++++++++++++++--------------------
udp.h | 2 +-
3 files changed, 27 insertions(+), 22 deletions(-)
diff --git a/passt.c b/passt.c
index e20bbad..fdd275a 100644
--- a/passt.c
+++ b/passt.c
@@ -164,7 +164,7 @@ static void timer_init(struct ctx *c, const struct timespec *now)
void proto_update_l2_buf(const unsigned char *eth_d, const unsigned char *eth_s)
{
tcp_update_l2_buf(eth_d, eth_s);
- udp_update_l2_buf(eth_d, eth_s);
+ udp_update_l2_buf(eth_d);
}
/**
diff --git a/udp.c b/udp.c
index 86585b7..eb57f05 100644
--- a/udp.c
+++ b/udp.c
@@ -133,11 +133,8 @@ static int udp_splice_init[IP_VERSIONS][NUM_PORTS];
/* UDP header and data for inbound messages */
static struct udp_payload_t udp_payload[UDP_MAX_FRAMES];
-/* Ethernet header for IPv4 frames */
-static struct ethhdr udp4_eth_hdr;
-
-/* Ethernet header for IPv6 frames */
-static struct ethhdr udp6_eth_hdr;
+/* Ethernet headers for IPv4 and IPv6 frames */
+static struct ethhdr udp_eth_hdr[UDP_MAX_FRAMES];
/**
* struct udp_meta_t - Pre-cooked headers for UDP packets
@@ -210,12 +207,13 @@ void udp_portmap_clear(void)
/**
* udp_update_l2_buf() - Update L2 buffers with Ethernet and IPv4 addresses
* @eth_d: Ethernet destination address, NULL if unchanged
- * @eth_s: Ethernet source address, NULL if unchanged
*/
-void udp_update_l2_buf(const unsigned char *eth_d, const unsigned char *eth_s)
+void udp_update_l2_buf(const unsigned char *eth_d)
{
- eth_update_mac(&udp4_eth_hdr, eth_d, eth_s);
- eth_update_mac(&udp6_eth_hdr, eth_d, eth_s);
+ int i;
+
+ for (i = 0; i < UDP_MAX_FRAMES; i++)
+ eth_update_mac(&udp_eth_hdr[i], eth_d, NULL);
}
/**
@@ -238,6 +236,7 @@ static void udp_iov_init_one(const struct ctx *c, size_t i)
*siov = IOV_OF_LVALUE(payload->data);
+ tiov[UDP_IOV_ETH] = IOV_OF_LVALUE(udp_eth_hdr[i]);
tiov[UDP_IOV_TAP] = tap_hdr_iov(c, &meta->taph);
tiov[UDP_IOV_PAYLOAD].iov_base = payload;
@@ -253,9 +252,6 @@ static void udp_iov_init(const struct ctx *c)
{
size_t i;
- udp4_eth_hdr.h_proto = htons_constant(ETH_P_IP);
- udp6_eth_hdr.h_proto = htons_constant(ETH_P_IPV6);
-
for (i = 0; i < UDP_MAX_FRAMES; i++)
udp_iov_init_one(c, i);
}
@@ -352,31 +348,34 @@ size_t udp_update_hdr6(struct ipv6hdr *ip6h, struct udp_payload_t *bp,
* udp_tap_prepare() - Convert one datagram into a tap frame
* @mmh: Receiving mmsghdr array
* @idx: Index of the datagram to prepare
+ * @tap_omac: MAC address of remote endpoint as seen from the guest
* @toside: Flowside for destination side
* @no_udp_csum: Do not set UDP checksum
*/
static void udp_tap_prepare(const struct mmsghdr *mmh,
- unsigned idx, const struct flowside *toside,
+ unsigned int idx,
+ const uint8_t *tap_omac,
+ const struct flowside *toside,
bool no_udp_csum)
{
struct iovec (*tap_iov)[UDP_NUM_IOVS] = &udp_l2_iov[idx];
struct udp_payload_t *bp = &udp_payload[idx];
struct udp_meta_t *bm = &udp_meta[idx];
+ struct ethhdr *eh = (*tap_iov)[UDP_IOV_ETH].iov_base;
size_t l4len;
+ eth_update_mac(eh, NULL, tap_omac);
if (!inany_v4(&toside->eaddr) || !inany_v4(&toside->oaddr)) {
l4len = udp_update_hdr6(&bm->ip6h, bp, toside,
mmh[idx].msg_len, no_udp_csum);
- tap_hdr_update(&bm->taph, l4len + sizeof(bm->ip6h) +
- sizeof(udp6_eth_hdr));
- (*tap_iov)[UDP_IOV_ETH] = IOV_OF_LVALUE(udp6_eth_hdr);
+ tap_hdr_update(&bm->taph, l4len + sizeof(bm->ip6h) + ETH_HLEN);
+ eh->h_proto = htons_constant(ETH_P_IPV6);
(*tap_iov)[UDP_IOV_IP] = IOV_OF_LVALUE(bm->ip6h);
} else {
l4len = udp_update_hdr4(&bm->ip4h, bp, toside,
mmh[idx].msg_len, no_udp_csum);
- tap_hdr_update(&bm->taph, l4len + sizeof(bm->ip4h) +
- sizeof(udp4_eth_hdr));
- (*tap_iov)[UDP_IOV_ETH] = IOV_OF_LVALUE(udp4_eth_hdr);
+ tap_hdr_update(&bm->taph, l4len + sizeof(bm->ip4h) + ETH_HLEN);
+ eh->h_proto = htons_constant(ETH_P_IP);
(*tap_iov)[UDP_IOV_IP] = IOV_OF_LVALUE(bm->ip4h);
}
(*tap_iov)[UDP_IOV_PAYLOAD].iov_len = l4len;
@@ -801,13 +800,19 @@ static void udp_buf_sock_to_tap(const struct ctx *c, int s, int n,
flow_sidx_t tosidx)
{
const struct flowside *toside = flowside_at_sidx(tosidx);
+ struct udp_flow *uflow = udp_at_sidx(tosidx);
+ uint8_t *omac = uflow->f.tap_omac;
int i;
if ((n = udp_sock_recv(c, s, udp_mh_recv, n)) <= 0)
return;
+ /* Make one attempt to find true MAC address in ARP/NDP table */
+ if (MAC_IS_ZERO(omac))
+ fwd_neigh_mac_get(c, &toside->oaddr, omac);
+
for (i = 0; i < n; i++)
- udp_tap_prepare(udp_mh_recv, i, toside, false);
+ udp_tap_prepare(udp_mh_recv, i, omac, toside, false);
tap_send_frames(c, &udp_l2_iov[0][0], UDP_NUM_IOVS, n);
}
diff --git a/udp.h b/udp.h
index 8f8531a..dd6e5ad 100644
--- a/udp.h
+++ b/udp.h
@@ -21,7 +21,7 @@ int udp_sock_init(const struct ctx *c, int ns, const union inany_addr *addr,
const char *ifname, in_port_t port);
int udp_init(struct ctx *c);
void udp_timer(struct ctx *c, const struct timespec *now);
-void udp_update_l2_buf(const unsigned char *eth_d, const unsigned char *eth_s);
+void udp_update_l2_buf(const unsigned char *eth_d);
/**
* union udp_listen_epoll_ref - epoll reference for "listening" UDP sockets
--
2.50.1