As soon as we bring up the interface, the Linux kernel will set up a
link-local address for it, so we can fetch it and start using right
away, if we need a link-local address to communicate to the container
before we see any traffic coming from it.
Signed-off-by: Stefano Brivio <sbrivio(a)redhat.com>
---
netlink.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
netlink.h | 1 +
pasta.c | 7 +++++++
3 files changed, 55 insertions(+)
diff --git a/netlink.c b/netlink.c
index 59f2fd9..06a3816 100644
--- a/netlink.c
+++ b/netlink.c
@@ -794,6 +794,53 @@ int nl_addr_get(int s, unsigned int ifi, sa_family_t af,
return status;
}
+/**
+ * nl_addr_get_ll() - Get first IPv6 link-local address for a given interface
+ * @s: Netlink socket
+ * @ifi: Interface index in outer network namespace
+ * @addr: Link-local address to fill
+ *
+ * Return: 0 on success, negative error code on failure
+ */
+int nl_addr_get_ll(int s, unsigned int ifi, struct in6_addr *addr)
+{
+ struct req_t {
+ struct nlmsghdr nlh;
+ struct ifaddrmsg ifa;
+ } req = {
+ .ifa.ifa_family = AF_INET6,
+ .ifa.ifa_index = ifi,
+ };
+ struct nlmsghdr *nh;
+ bool found = false;
+ 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) {
+ struct ifaddrmsg *ifa = (struct ifaddrmsg *)NLMSG_DATA(nh);
+ struct rtattr *rta;
+ size_t na;
+
+ if (ifa->ifa_index != ifi || ifa->ifa_scope != RT_SCOPE_LINK ||
+ found)
+ continue;
+
+ for (rta = IFA_RTA(ifa), na = IFA_PAYLOAD(nh); RTA_OK(rta, na);
+ rta = RTA_NEXT(rta, na)) {
+ if (rta->rta_type != IFA_ADDRESS)
+ continue;
+
+ if (!found) {
+ memcpy(addr, RTA_DATA(rta), RTA_PAYLOAD(rta));
+ found = true;
+ }
+ }
+ }
+ return status;
+}
+
/**
* nl_add_set() - Set IP addresses for given interface and address family
* @s: Netlink socket
diff --git a/netlink.h b/netlink.h
index 66a44ad..b51e99c 100644
--- a/netlink.h
+++ b/netlink.h
@@ -19,6 +19,7 @@ int nl_addr_get(int s, unsigned int ifi, sa_family_t af,
void *addr, int *prefix_len, void *addr_l);
int nl_addr_set(int s, unsigned int ifi, sa_family_t af,
const void *addr, int prefix_len);
+int nl_addr_get_ll(int s, unsigned int ifi, struct in6_addr *addr);
int nl_addr_set_ll_nodad(int s, unsigned int ifi);
int nl_addr_dup(int s_src, unsigned int ifi_src,
int s_dst, unsigned int ifi_dst, sa_family_t af);
diff --git a/pasta.c b/pasta.c
index 17eed15..e8883bd 100644
--- a/pasta.c
+++ b/pasta.c
@@ -340,6 +340,13 @@ void pasta_ns_conf(struct ctx *c)
}
if (c->ifi6) {
+ rc = nl_addr_get_ll(nl_sock_ns, c->pasta_ifi,
+ &c->ip6.addr_ll_seen);
+ if (rc < 0) {
+ warn("Can't get LL address from namespace: %s",
+ strerror(-rc));
+ }
+
rc = nl_addr_set_ll_nodad(nl_sock_ns, c->pasta_ifi);
if (rc < 0) {
warn("Can't set nodad for LL in namespace: %s",
--
2.43.0