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| author | Nicolas Dichtel <nicolas.dichtel@6wind.com> | 2019-06-24 16:01:09 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2019-06-26 13:26:08 -0700 |
| commit | 2c6b55f45d53420d8310d41310e0e2cd41fe073f (patch) | |
| tree | 5a3157b02ac8196710f12cd0d7964c7e2a8913cc /net/ipv6/route.c | |
| parent | 9b1c1ef13b35fa35051b635ca9fbda39fe6bbc70 (diff) | |
| download | lwn-2c6b55f45d53420d8310d41310e0e2cd41fe073f.tar.gz lwn-2c6b55f45d53420d8310d41310e0e2cd41fe073f.zip | |
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/ipv6/route.c')
| -rw-r--r-- | net/ipv6/route.c | 3 |
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) |