path: root/net
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authorNicolas Dichtel <nicolas.dichtel@6wind.com>2019-06-24 16:01:09 +0200
committerDavid S. Miller <davem@davemloft.net>2019-06-26 13:26:08 -0700
commit2c6b55f45d53420d8310d41310e0e2cd41fe073f (patch)
tree5a3157b02ac8196710f12cd0d7964c7e2a8913cc /net
parent9b1c1ef13b35fa35051b635ca9fbda39fe6bbc70 (diff)
ipv6: fix neighbour resolution with raw socket
The scenario is the following: the user uses a raw socket to send an ipv6 packet, destinated to a not-connected network, and specify a connected nh. Here is the corresponding python script to reproduce this scenario: import socket IPPROTO_RAW = 255 send_s = socket.socket(socket.AF_INET6, socket.SOCK_RAW, IPPROTO_RAW) # scapy # p = IPv6(src='fd00:100::1', dst='fd00:200::fa')/ICMPv6EchoRequest() # str(p) req = b'`\x00\x00\x00\x00\x08:@\xfd\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\xfd\x00\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xfa\x80\x00\x81\xc0\x00\x00\x00\x00' send_s.sendto(req, ('fd00:175::2', 0, 0, 0)) fd00:175::/64 is a connected route and fd00:200::fa is not a connected host. With this scenario, the kernel starts by sending a NS to resolve fd00:175::2. When it receives the NA, it flushes its queue and try to send the initial packet. But instead of sending it, it sends another NS to resolve fd00:200::fa, which obvioulsy fails, thus the packet is dropped. If the user sends again the packet, it now uses the right nh (fd00:175::2). The problem is that ip6_dst_lookup_neigh() uses the rt6i_gateway, which is :: because the associated route is a connected route, thus it uses the dst addr of the packet. Let's use rt6_nexthop() to choose the right nh. Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
1 files changed, 2 insertions, 1 deletions
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index aade636c6be6..97a843cf164c 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -218,7 +218,8 @@ static struct neighbour *ip6_dst_neigh_lookup(const struct dst_entry *dst,
const struct rt6_info *rt = container_of(dst, struct rt6_info, dst);
- return ip6_neigh_lookup(&rt->rt6i_gateway, dst->dev, skb, daddr);
+ return ip6_neigh_lookup(rt6_nexthop(rt, &in6addr_any),
+ dst->dev, skb, daddr);
static void ip6_confirm_neigh(const struct dst_entry *dst, const void *daddr)