[PATCH 3.4 119/125] ipv6: fix handling of blackhole and prohibit routes

From: lizf
Date: Wed Oct 12 2016 - 08:45:41 EST


From: Nicolas Dichtel <nicolas.dichtel@xxxxxxxxx>

3.4.113-rc1 review patch. If anyone has any objections, please let me know.

------------------


commit ef2c7d7b59708d54213c7556a82d14de9a7e4475 upstream.

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

v2: wrong patch
v3: add a field fc_type in struct fib6_config to store RTN_* type

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Zefan Li <lizefan@xxxxxxxxxx>
---
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 49c4cfe..acaab5e 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 28957ba..794cd2a 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1399,8 +1399,18 @@ 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 RTN_BLACKHOLE:
+ rt->dst.error = -EINVAL;
+ break;
+ case RTN_PROHIBIT:
+ rt->dst.error = -EACCES;
+ break;
+ default:
+ rt->dst.error = -ENETUNREACH;
+ break;
+ }
goto install_route;
}

@@ -2343,8 +2353,11 @@ 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->fc_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)
@@ -2474,8 +2487,19 @@ static int rt6_fill_node(struct net *net,
table = RT6_TABLE_UNSPEC;
rtm->rtm_table = table;
NLA_PUT_U32(skb, RTA_TABLE, table);
- 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))
--
1.9.1