Host routes can include a preferred source address (RTA_PREFSRC), which
must be one of the host's addresses. However when using pasta with -a the
namespace might be given a different address, not on the host. This seems
to occur pretty routinely depending on the network configuration systems
in place on the host.
With --config-net we will try to copy host routes to the namespace. If
one of those includes an RTA_PREFSRC, but the namespace doesn't have the
host address, this will fail with -EINVAL, causing pasta to fail.
Fix this by stripping off RTA_PREFSRC attributes from routes as we copy
them to the namespace. This is by no means infallible, bit it should at
least handle common cases for the time being.
Link: https://bugs.passt.top/show_bug.cgi?id=71
Link: https://github.com/containers/podman/pull/19699#issuecomment-1688769287
Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au>
---
netlink.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
diff --git a/netlink.c b/netlink.c
index f55f2c3..98f08e7 100644
--- a/netlink.c
+++ b/netlink.c
@@ -462,8 +462,21 @@ int nl_route_dup(int s_src, unsigned int ifi_src,
for (rta = RTM_RTA(rtm), na = RTM_PAYLOAD(nh); RTA_OK(rta, na);
rta = RTA_NEXT(rta, na)) {
- if (rta->rta_type == RTA_OIF)
+ if (rta->rta_type == RTA_OIF) {
+ /* The host obviously list's the host interface
+ * id here, we need to change it to the
+ * namespace's interface id
+ */
*(unsigned int *)RTA_DATA(rta) = ifi_dst;
+ } else if (rta->rta_type == RTA_PREFSRC) {
+ /* Host routes might include a preferred source
+ * address, which must be one of the host's
+ * addresses. However, with -a pasta will use a
+ * different namespace address, making such a
+ * route invalid in the namespace. Strip off
+ * RTA_PREFSRC attributes to avoid that. */
+ rta->rta_type = RTA_UNSPEC;
+ }
}
}
--
2.41.0