conf, pasta: With --config-net, copy all routes by default

Use the newly-introduced NL_DUP mode for nl_route() to copy all the
routes associated to the template interface in the outer namespace,
unless --no-copy-routes (also implied by -g) is given.

This option is introduced as deprecated right away: it's not expected
to be of any use, but it's helpful to keep it around for a while to
debug any suspected issue with this change.

Otherwise, we can't use default gateways which are not, address-wise,
on the same subnet as the container, as reported by Callum.

Reported-by: Callum Parsey <callum@neoninteger.au>
Link: https://github.com/containers/podman/issues/18539
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 4 insertions, 2 deletions

diff --git a/pasta.c b/pasta.c
index c9bf1d3..c2fb1f4 100644
--- a/pasta.c
+++ b/pasta.c
@@ -273,12 +273,14 @@ void pasta_ns_conf(struct ctx *c)
 	nl_link(1, 1 /* lo */, MAC_ZERO, 1, 0);
 
 	if (c->pasta_conf_ns) {
+		enum nl_op op_routes = c->no_copy_routes ? NL_SET : NL_DUP;
+
 		nl_link(1, c->pasta_ifi, c->mac_guest, 1, c->mtu);
 
 		if (c->ifi4) {
 			nl_addr(1, c->pasta_ifi, AF_INET, &c->ip4.addr,
 				&c->ip4.prefix_len, NULL);
-			nl_route(NL_SET, c->ifi4, c->pasta_ifi, AF_INET,
+			nl_route(op_routes, c->ifi4, c->pasta_ifi, AF_INET,
 				 &c->ip4.gw);
 		}
 
@@ -286,7 +288,7 @@ void pasta_ns_conf(struct ctx *c)
 			int prefix_len = 64;
 			nl_addr(1, c->pasta_ifi, AF_INET6, &c->ip6.addr,
 				&prefix_len, NULL);
-			nl_route(NL_SET, c->ifi6, c->pasta_ifi, AF_INET6,
+			nl_route(op_routes, c->ifi6, c->pasta_ifi, AF_INET6,
 				 &c->ip6.gw);
 		}
 	} else {