As soon as we the kernel notifier for IPv6 address configuration
(addrconf_notify()) sees that we bring the target interface up
(NETDEV_UP), it will schedule duplicate address detection, so, by
itself, setting the nodad flag later is useless, because that won't
stop a detection that's already in progress.
However, if we disable neighbour solicitations with IFF_NOARP (which
is a misnomer for IPv6 interfaces, but there's no possibility of
mixing things up), the notifier will not trigger DAD, because it can't
be done, of course, without neighbour solicitations.
Set IFF_NOARP as we bring up the device, and drop it after we had a
chance to set the nodad attribute on the link.
Signed-off-by: Stefano Brivio <sbrivio(a)redhat.com>
Reviewed-by: David Gibson <david(a)gibson.dropbear.id.au>
---
netlink.c | 22 ++++++++++++----------
pasta.c | 11 ++++++++++-
2 files changed, 22 insertions(+), 11 deletions(-)
diff --git a/netlink.c b/netlink.c
index 06a3816..9592b1b 100644
--- a/netlink.c
+++ b/netlink.c
@@ -689,11 +689,10 @@ int nl_addr_set_ll_nodad(int s, unsigned int ifi)
.ifa.ifa_family = AF_INET6,
.ifa.ifa_index = ifi,
};
- unsigned ll_addrs = 0;
+ uint32_t seq, last_seq = 0;
+ ssize_t status, ret = 0;
struct nlmsghdr *nh;
char buf[NLBUFSIZ];
- ssize_t status;
- uint32_t seq;
seq = nl_send(s, &req, RTM_GETADDR, NLM_F_DUMP, sizeof(req));
nl_foreach_oftype(nh, status, s, buf, seq, RTM_NEWADDR) {
@@ -713,19 +712,22 @@ int nl_addr_set_ll_nodad(int s, unsigned int ifi)
*(uint32_t *)RTA_DATA(rta) |= IFA_F_NODAD;
}
- nl_send(s, nh, RTM_NEWADDR, NLM_F_REPLACE, nh->nlmsg_len);
- ll_addrs++;
+ last_seq = nl_send(s, nh, RTM_NEWADDR, NLM_F_REPLACE,
+ nh->nlmsg_len);
}
if (status < 0)
- return status;
+ ret = status;
- seq += ll_addrs;
+ for (seq = seq + 1; seq <= last_seq; seq++) {
+ nl_foreach(nh, status, s, buf, seq)
+ warn("netlink: Unexpected response message");
- nl_foreach(nh, status, s, buf, seq)
- warn("netlink: Unexpected response message");
+ if (!ret && status < 0)
+ ret = status;
+ }
- return status;
+ return ret;
}
/**
diff --git a/pasta.c b/pasta.c
index e8883bd..1142f03 100644
--- a/pasta.c
+++ b/pasta.c
@@ -303,10 +303,15 @@ void pasta_ns_conf(struct ctx *c)
strerror(-rc));
if (c->pasta_conf_ns) {
+ unsigned int flags = IFF_UP;
+
if (c->mtu != -1)
nl_link_set_mtu(nl_sock_ns, c->pasta_ifi, c->mtu);
- nl_link_set_flags(nl_sock_ns, c->pasta_ifi, IFF_UP, IFF_UP);
+ if (c->ifi6) /* Avoid duplicate address detection on link up */
+ flags |= IFF_NOARP;
+
+ nl_link_set_flags(nl_sock_ns, c->pasta_ifi, flags, flags);
if (c->ifi4) {
if (c->ip4.no_copy_addrs) {
@@ -353,6 +358,10 @@ void pasta_ns_conf(struct ctx *c)
strerror(-rc));
}
+ /* We dodged DAD: re-enable neighbour solicitations */
+ nl_link_set_flags(nl_sock_ns, c->pasta_ifi,
+ 0, IFF_NOARP);
+
if (c->ip6.no_copy_addrs) {
rc = nl_addr_set(nl_sock_ns, c->pasta_ifi,
AF_INET6, &c->ip6.addr, 64);
--
2.43.0