Merge commit '98bb80a243b58c43453e9be69d19d0350286549c' into int-new

1 files changed, 41 insertions, 13 deletions

diff --git a/sysdep/linux/netlink.c b/sysdep/linux/netlink.c
index 6cea2fa9..279f3c9c 100644
--- a/sysdep/linux/netlink.c
+++ b/sysdep/linux/netlink.c
@@ -83,22 +83,26 @@ struct rtvia {
 /*
  * Structure nl_parse_state keeps state of received route processing. Ideally,
  * we could just independently parse received Netlink messages and immediately
- * propagate received routes to the rest of BIRD, but Linux kernel represents
- * and announces IPv6 ECMP routes not as one route with multiple next hops (like
- * RTA_MULTIPATH in IPv4 ECMP), but as a set of routes with the same prefix.
+ * propagate received routes to the rest of BIRD, but older Linux kernel (before
+ * version 4.11) represents and announces IPv6 ECMP routes not as one route with
+ * multiple next hops (like RTA_MULTIPATH in IPv4 ECMP), but as a sequence of
+ * routes with the same prefix. More recent kernels work as with IPv4.
  *
  * Therefore, BIRD keeps currently processed route in nl_parse_state structure
  * and postpones its propagation until we expect it to be final; i.e., when
  * non-matching route is received or when the scan ends. When another matching
  * route is received, it is merged with the already processed route to form an
  * ECMP route. Note that merging is done only for IPv6 (merge == 1), but the
- * postponing is done in both cases (for simplicity). All IPv4 routes are just
- * considered non-matching.
+ * postponing is done in both cases (for simplicity). All IPv4 routes or IPv6
+ * routes with RTA_MULTIPATH set are just considered non-matching.
  *
  * This is ignored for asynchronous notifications (every notification is handled
  * as a separate route). It is not an issue for our routes, as we ignore such
  * notifications anyways. But importing alien IPv6 ECMP routes does not work
- * properly.
+ * properly with older kernels.
+ *
+ * Whatever the kernel version is, IPv6 ECMP routes are sent as multiple routes
+ * for the same prefix.
  */
 
 struct nl_parse_state
@@ -348,6 +352,12 @@ static struct nl_want_attrs nexthop_attr_want4[BIRD_RTA_MAX] = {
   [RTA_ENCAP]	  = { 1, 0, 0 },
 };
 
+static struct nl_want_attrs nexthop_attr_want6[BIRD_RTA_MAX] = {
+  [RTA_GATEWAY]	  = { 1, 1, sizeof(ip6_addr) },
+  [RTA_ENCAP_TYPE]= { 1, 1, sizeof(u16) },
+  [RTA_ENCAP]	  = { 1, 0, 0 },
+};
+
 static struct nl_want_attrs encap_mpls_want[BIRD_RTA_MAX] = {
   [RTA_DST]       = { 1, 0, 0 },
 };
@@ -374,6 +384,7 @@ static struct nl_want_attrs rtm_attr_want6[BIRD_RTA_MAX] = {
   [RTA_PRIORITY]  = { 1, 1, sizeof(u32) },
   [RTA_PREFSRC]	  = { 1, 1, sizeof(ip6_addr) },
   [RTA_METRICS]	  = { 1, 0, 0 },
+  [RTA_MULTIPATH] = { 1, 0, 0 },
   [RTA_FLOW]	  = { 1, 1, sizeof(u32) },
   [RTA_TABLE]	  = { 1, 1, sizeof(u32) },
   [RTA_ENCAP_TYPE]= { 1, 1, sizeof(u16) },
@@ -631,7 +642,7 @@ nl_add_multipath(struct nlmsghdr *h, uint bufsize, struct nexthop *nh, int af)
 }
 
 static struct nexthop *
-nl_parse_multipath(struct krt_proto *p, struct rtattr *ra)
+nl_parse_multipath(struct krt_proto *p, struct rtattr *ra, int af)
 {
   /* Temporary buffer for multicast nexthops */
   static struct nexthop *nh_buffer;
@@ -670,7 +681,22 @@ nl_parse_multipath(struct krt_proto *p, struct rtattr *ra)
 
       /* Nonexistent RTNH_PAYLOAD ?? */
       nl_attr_len = nh->rtnh_len - RTNH_LENGTH(0);
-      nl_parse_attrs(RTNH_DATA(nh), nexthop_attr_want4, a, sizeof(a));
+      switch (af)
+        {
+	case AF_INET:
+	  if (!nl_parse_attrs(RTNH_DATA(nh), nexthop_attr_want4, a, sizeof(a)))
+	    return NULL;
+	  break;
+
+	case AF_INET6:
+	  if (!nl_parse_attrs(RTNH_DATA(nh), nexthop_attr_want6, a, sizeof(a)))
+	    return NULL;
+	  break;
+
+	default:
+	  return NULL;
+	}
+
       if (a[RTA_GATEWAY])
 	{
 	  rv->gw = rta_get_ipa(a[RTA_GATEWAY]);
@@ -1520,9 +1546,9 @@ nl_parse_route(struct nl_parse_state *s, struct nlmsghdr *h)
     case RTN_UNICAST:
       ra->dest = RTD_UNICAST;
 
-      if (a[RTA_MULTIPATH] && (i->rtm_family == AF_INET))
-	{
-	  struct nexthop *nh = nl_parse_multipath(p, a[RTA_MULTIPATH]);
+      if (a[RTA_MULTIPATH])
+        {
+	  struct nexthop *nh = nl_parse_multipath(p, a[RTA_MULTIPATH], i->rtm_family);
 	  if (!nh)
 	    {
 	      log(L_ERR "KRT: Received strange multipath route %N", net->n.addr);
@@ -1699,8 +1725,10 @@ nl_parse_route(struct nl_parse_state *s, struct nlmsghdr *h)
 
   /*
    * Ideally, now we would send the received route to the rest of kernel code.
-   * But IPv6 ECMP routes are sent as a sequence of routes, so we postpone it
-   * and merge next hops until the end of the sequence.
+   * But IPv6 ECMP routes before 4.11 are sent as a sequence of routes, so we
+   * postpone it and merge next hops until the end of the sequence. Note that
+   * proper multipath updates are rejected by nl_mergable_route(), so it is
+   * always the first case for them.
    */
 
   if (!s->net)