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authorNicolas Dichtel <nicolas.dichtel@6wind.com>2019-01-17 11:27:22 +0100
committerDavid S. Miller <davem@davemloft.net>2019-01-17 15:54:45 -0800
commit88a8121dc1d3d0dbddd411b79ed236b6b6ea415c (patch)
treeaa01cb7d867212cfea8cbec31c407b8421dc8ce5 /net/packet
parentf7c46156f4a9d6ba5c6bcc5c48945e87b0f08c65 (diff)
downloadlinux-stericsson-88a8121dc1d3d0dbddd411b79ed236b6b6ea415c.tar.gz
af_packet: fix raw sockets over 6in4 tunnel
Since commit cb9f1b783850, scapy (which uses an AF_PACKET socket in SOCK_RAW mode) is unable to send a basic icmp packet over a sit tunnel: Here is a example of the setup: $ ip link set ntfp2 up $ ip addr add 10.125.0.1/24 dev ntfp2 $ ip tunnel add tun1 mode sit ttl 64 local 10.125.0.1 remote 10.125.0.2 dev ntfp2 $ ip addr add fd00:cafe:cafe::1/128 dev tun1 $ ip link set dev tun1 up $ ip route add fd00:200::/64 dev tun1 $ scapy >>> p = [] >>> p += IPv6(src='fd00:100::1', dst='fd00:200::1')/ICMPv6EchoRequest() >>> send(p, count=1, inter=0.1) >>> quit() $ ip -s link ls dev tun1 | grep -A1 "TX.*errors" TX: bytes packets errors dropped carrier collsns 0 0 1 0 0 0 The problem is that the network offset is set to the hard_header_len of the output device (tun1, ie 14 + 20) and in our case, because the packet is small (48 bytes) the pskb_inet_may_pull() fails (it tries to pull 40 bytes (ipv6 header) starting from the network offset). This problem is more generally related to device with variable hard header length. To avoid a too intrusive patch in the current release, a (ugly) workaround is proposed in this patch. It has to be cleaned up in net-next. Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=993675a3100b1 Link: http://patchwork.ozlabs.org/patch/1024489/ Fixes: cb9f1b783850 ("ip: validate header length on virtual device xmit") CC: Willem de Bruijn <willemb@google.com> CC: Maxim Mikityanskiy <maximmi@mellanox.com> Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Acked-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/packet')
-rw-r--r--net/packet/af_packet.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index d0945253f43b..3b1a78906bc0 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2887,7 +2887,8 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
goto out_free;
} else if (reserve) {
skb_reserve(skb, -reserve);
- if (len < reserve)
+ if (len < reserve + sizeof(struct ipv6hdr) &&
+ dev->min_header_len != dev->hard_header_len)
skb_reset_network_header(skb);
}