From 3f190726407109fdb74ed7b5f8ddd7e68a56d7aa Mon Sep 17 00:00:00 2001 From: David Gibson Date: Fri, 22 Jul 2022 15:31:14 +1000 Subject: [PATCH] Initialize host side MAC when in IPv6 only mode When sending packets to the guest we need a source MAC address, which we currently take from the host side interface we're using (though it's basically arbitrary). However if not given on the command line this MAC is initialized in an IPv4 specific path, and will end up as 00:00:00:00:00:00 when running "passt 6". The MAC address is also used for IPv6 packets, though. Interestingly, we largely seem to get away with using an all-zero MAC, but it's probably not a good idea. Make the IPv6 path pick the MAC address from its interface if the IPv4 path hasn't already done so. While we're there, use the existing MAC_IS_ZERO macro to make the code a little clearer. Signed-off-by: David Gibson --- conf.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/conf.c b/conf.c index cc08de3..bc8851f 100644 --- a/conf.c +++ b/conf.c @@ -672,7 +672,7 @@ static void conf_ip(struct ctx *c) memcpy(&c->addr4_seen, &c->addr4, sizeof(c->addr4_seen)); - if (!memcmp(c->mac, MAC_ZERO, ETH_ALEN)) + if (MAC_IS_ZERO(c->mac)) nl_link(0, c->ifi4, c->mac, 0, 0); } @@ -691,17 +691,20 @@ static void conf_ip(struct ctx *c) memcpy(&c->addr6_seen, &c->addr6, sizeof(c->addr6)); memcpy(&c->addr6_ll_seen, &c->addr6_ll, sizeof(c->addr6_ll)); + + if (MAC_IS_ZERO(c->mac)) + nl_link(0, c->ifi6, c->mac, 0, 0); } - if (!c->gw4 || !c->addr4 || - !memcmp(c->mac, ((uint8_t [ETH_ALEN]){ 0 }), ETH_ALEN)) + if (!c->gw4 || !c->addr4 || MAC_IS_ZERO(c->mac)) v4 = IP_VERSION_DISABLED; else v4 = IP_VERSION_ENABLED; if (IN6_IS_ADDR_UNSPECIFIED(&c->gw6) || IN6_IS_ADDR_UNSPECIFIED(&c->addr6) || - IN6_IS_ADDR_UNSPECIFIED(&c->addr6_ll)) + IN6_IS_ADDR_UNSPECIFIED(&c->addr6_ll) || + MAC_IS_ZERO(c->mac)) v6 = IP_VERSION_DISABLED; else v6 = IP_VERSION_ENABLED; @@ -905,12 +908,12 @@ static void conf_print(const struct ctx *c) if (c->mode == MODE_PASTA) info("Namespace interface: %s", c->pasta_ifn); - if (c->v4) { - info("ARP:"); - info(" address: %02x:%02x:%02x:%02x:%02x:%02x", - c->mac[0], c->mac[1], c->mac[2], - c->mac[3], c->mac[4], c->mac[5]); + info("MAC:"); + info(" host: %02x:%02x:%02x:%02x:%02x:%02x", + c->mac[0], c->mac[1], c->mac[2], + c->mac[3], c->mac[4], c->mac[5]); + if (c->v4) { if (!c->no_dhcp) { info("DHCP:"); info(" assign: %s",