From a7359f09489803e501c85c7158b9462c6b3df465 Mon Sep 17 00:00:00 2001 From: Stefano Brivio Date: Sun, 14 May 2023 16:24:11 +0200 Subject: [PATCH] conf: Don't exit if sourced default route has no gateway If we use a template interface without a gateway on the default route, we can still offer almost complete functionality, except that, of course, we can't map the gateway address to the outer namespace or host, and that we have no obvious server address or identifier for use in DHCP's siaddr and option 54 (Server identifier, mandatory). Continue, if we have a default route but no default gateway, and imply --no-map-gw and --no-dhcp in that case. NDP responder and DHCPv6 should be able to work as usual because we require a link-local address to be present, and we'll fall back to that. Together with the previous commits implementing an actual copy of routes from the outer namespace, this should finally fix the operation of 'pasta --config-net' for cases where we have a default route on the host, but no default gateway, as it's the case for tap-style routes, including typical Wireguard endpoints. Reported-by: me@yawnt.com Link: https://bugs.passt.top/show_bug.cgi?id=49 Signed-off-by: Stefano Brivio Reviewed-by: David Gibson --- conf.c | 10 +++++++--- passt.1 | 6 ++++-- 2 files changed, 11 insertions(+), 5 deletions(-) diff --git a/conf.c b/conf.c index d3d58a7..404c7bc 100644 --- a/conf.c +++ b/conf.c @@ -665,8 +665,7 @@ static unsigned int conf_ip4(unsigned int ifi, if (MAC_IS_ZERO(mac)) nl_link(0, ifi, mac, 0, 0); - if (IN4_IS_ADDR_UNSPECIFIED(&ip4->gw) || - IN4_IS_ADDR_UNSPECIFIED(&ip4->addr) || + if (IN4_IS_ADDR_UNSPECIFIED(&ip4->addr) || MAC_IS_ZERO(mac)) return 0; @@ -708,7 +707,6 @@ static unsigned int conf_ip6(unsigned int ifi, nl_link(0, ifi, mac, 0, 0); if (IN6_IS_ADDR_UNSPECIFIED(&ip6->gw) || - IN6_IS_ADDR_UNSPECIFIED(&ip6->addr) || IN6_IS_ADDR_UNSPECIFIED(&ip6->addr_ll) || MAC_IS_ZERO(mac)) return 0; @@ -1660,6 +1658,12 @@ void conf(struct ctx *c, int argc, char **argv) (*c->ip6.ifname_out && !c->ifi6)) die("External interface not usable"); + if (c->ifi4 && IN4_IS_ADDR_UNSPECIFIED(&c->ip4.gw)) + c->no_map_gw = c->no_dhcp = 1; + + if (c->ifi6 && IN6_IS_ADDR_UNSPECIFIED(&c->ip6.gw)) + c->no_map_gw = 1; + /* Inbound port options can be parsed now (after IPv4/IPv6 settings) */ optind = 1; do { diff --git a/passt.1 b/passt.1 index ee2803a..96ce96e 100644 --- a/passt.1 +++ b/passt.1 @@ -281,7 +281,8 @@ guest or target namespace will be silently dropped. .TP .BR \-\-no-dhcp Disable the DHCP server. DHCP client requests coming from guest or target -namespace will be silently dropped. +namespace will be silently dropped. Implied if there is no gateway on the +selected IPv4 default route. .TP .BR \-\-no-ndp @@ -301,7 +302,8 @@ namespace will be ignored. .TP .BR \-\-no-map-gw Don't remap TCP connections and untracked UDP traffic, with the gateway address -as destination, to the host. +as destination, to the host. Implied if there is no gateway on the selected +default route for any of the enabled address families. .TP .BR \-4 ", " \-\-ipv4-only