From: Jon Maloy <jmaloy@redhat.com>
To: sbrivio@redhat.com, dgibson@redhat.com, jmaloy@redhat.com,
passt-dev@passt.top
Subject: [PATCH v2 4/8] udp: forward external source mac address through tap interface
Date: Thu, 12 Jun 2025 00:21:48 -0400 [thread overview]
Message-ID: <20250612042152.695879-5-jmaloy@redhat.com> (raw)
In-Reply-To: <20250612042152.695879-1-jmaloy@redhat.com>
We forward the incoming mac address through the tap interface when
receiving incoming packets from network local hosts. Packets from
the local host are excepted from this rule, and are still forwarded
with the default passt/pasta mac address as source.
This is a part of the solution to bug #120
Signed-off-by: Jon Maloy <jmaloy@redhat.com>
---
udp.c | 29 +++++++++++++----------------
1 file changed, 13 insertions(+), 16 deletions(-)
diff --git a/udp.c b/udp.c
index 65a52e0..ae8fbaf 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
@@ -214,8 +211,10 @@ void udp_portmap_clear(void)
*/
void udp_update_l2_buf(const unsigned char *eth_d, const unsigned char *eth_s)
{
- 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, eth_s);
}
/**
@@ -238,6 +237,7 @@ 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 +253,6 @@ 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);
}
@@ -362,21 +359,21 @@ static void udp_tap_prepare(const struct mmsghdr *mmh,
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, 0, toside->mac);
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;
--
@@ -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
@@ -214,8 +211,10 @@ void udp_portmap_clear(void)
*/
void udp_update_l2_buf(const unsigned char *eth_d, const unsigned char *eth_s)
{
- 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, eth_s);
}
/**
@@ -238,6 +237,7 @@ 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 +253,6 @@ 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);
}
@@ -362,21 +359,21 @@ static void udp_tap_prepare(const struct mmsghdr *mmh,
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, 0, toside->mac);
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;
--
2.48.1
next prev parent reply other threads:[~2025-06-12 4:22 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-12 4:21 [PATCH v2 0/8] use true mac address of LAN local remote hosts Jon Maloy
2025-06-12 4:21 ` [PATCH v2 1/8] netlink: Add function to extract mac addresses from arp table Jon Maloy
2025-06-12 15:17 ` Stefano Brivio
2025-06-13 6:11 ` David Gibson
2025-06-12 4:21 ` [PATCH v2 2/8] arp: respond with true mac address of LAN local remote hosts Jon Maloy
2025-06-12 15:17 ` Stefano Brivio
2025-06-12 4:21 ` [PATCH v2 3/8] flow: add mac address of LAN local remote hosts to flow Jon Maloy
2025-06-12 15:17 ` Stefano Brivio
2025-06-14 13:22 ` David Gibson
2025-06-12 4:21 ` Jon Maloy [this message]
2025-06-12 15:17 ` [PATCH v2 4/8] udp: forward external source mac address through tap interface Stefano Brivio
2025-06-12 4:21 ` [PATCH v2 5/8] tcp: " Jon Maloy
2025-06-12 15:17 ` Stefano Brivio
2025-06-12 4:21 ` [PATCH v2 6/8] tap: change signature of function tap_push_l2h() Jon Maloy
2025-06-12 15:17 ` Stefano Brivio
2025-06-12 4:21 ` [PATCH v2 7/8] tcp: make tcp_rst_no_conn() respond with correct mac address Jon Maloy
2025-06-12 15:17 ` Stefano Brivio
2025-06-12 4:21 ` [PATCH v2 8/8] icmp: let icmp use mac address from flowside structure Jon Maloy
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