When adding a blackhole or a prohibit route, they were handling like classic
routes. Moreover, it was only possible to add this kind of routes by specifying
an interface.

Bug already reported here:
   http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=498498

Before the patch:
   $ ip route add blackhole 2001::1/128
   RTNETLINK answers: No such device
   $ ip route add blackhole 2001::1/128 dev eth0
   $ ip -6 route | grep 2001
   2001::1 dev eth0  metric 1024

After:
   $ ip route add blackhole 2001::1/128
   $ ip -6 route | grep 2001
   blackhole 2001::1 dev lo  metric 1024  error -22

Signed-off-by: Nicolas Dichtel <redacted>
---
  include/net/ip6_fib.h |  1 +
  net/ipv6/route.c      | 32 ++++++++++++++++++++++++++++----
  2 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index 0fedbd8..cd64cf3 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h

@@ -37,6 +37,7 @@ struct fib6_config {
  	int		fc_ifindex;
  	u32		fc_flags;
  	u32		fc_protocol;
+	u32		fc_type;	/* only 8 bits are used */

  	struct in6_addr	fc_dst;
  	struct in6_addr	fc_src;

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 8e80fd2..5642fb5 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c

@@ -1463,8 +1463,18 @@ int ip6_route_add(struct fib6_config *cfg)
  		}
  		rt->dst.output = ip6_pkt_discard_out;
  		rt->dst.input = ip6_pkt_discard;
-		rt->dst.error = -ENETUNREACH;
  		rt->rt6i_flags = RTF_REJECT|RTF_NONEXTHOP;
+		switch (cfg->fc_type) {
+		case RTM_BLACKHOLE:
+			rt->dst.error = -EINVAL;
+			break;
+		case RTM_PROHIBIT:
+			rt->dst.error = -EACCES;
+			break;
+		default:
+			rt->dst.error = -ENETUNREACH;
+			break;
+		}
  		goto install_route;
  	}

@@ -2261,8 +2271,11 @@ static int rtm_to_fib6_config(struct sk_buff *skb, struct nlmsghdr *nlh,
  	cfg->fc_src_len = rtm->rtm_src_len;
  	cfg->fc_flags = RTF_UP;
  	cfg->fc_protocol = rtm->rtm_protocol;
+	cfg->type = rtm->rtm_type;

-	if (rtm->rtm_type == RTN_UNREACHABLE)
+	if (rtm->rtm_type == RTN_UNREACHABLE ||
+	    rtm->rtm_type == RTN_BLACKHOLE ||
+	    rtm->rtm_type == RTN_PROHIBIT)
  		cfg->fc_flags |= RTF_REJECT;

  	if (rtm->rtm_type == RTN_LOCAL)

@@ -2391,8 +2404,19 @@ static int rt6_fill_node(struct net *net,
  	rtm->rtm_table = table;
  	if (nla_put_u32(skb, RTA_TABLE, table))
  		goto nla_put_failure;
-	if (rt->rt6i_flags & RTF_REJECT)
-		rtm->rtm_type = RTN_UNREACHABLE;
+	if (rt->rt6i_flags & RTF_REJECT) {
+		switch (rt->dst.error) {
+		case -EINVAL:
+			rtm->rtm_type = RTN_BLACKHOLE;
+			break;
+		case -EACCES:
+			rtm->rtm_type = RTN_PROHIBIT;
+			break;
+		default:
+			rtm->rtm_type = RTN_UNREACHABLE;
+			break;
+		}
+	}
  	else if (rt->rt6i_flags & RTF_LOCAL)
  		rtm->rtm_type = RTN_LOCAL;
  	else if (rt->dst.dev && (rt->dst.dev->flags & IFF_LOOPBACK))