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authorDaniel Borkmann <daniel@iogearbox.net>2015-11-11 23:25:43 +0100
committerDavid S. Miller <davem@davemloft.net>2015-11-15 18:00:35 -0500
commitc72219b75fde768efccf7666342282fab7f9e4e7 (patch)
tree5d58d422d2fb6349c8f68eedc578042cfc0efd9a /net
parent3c70c132488794e2489ab045559b0ce0afcf17de (diff)
packet: infer protocol from ethernet header if unset
In case no struct sockaddr_ll has been passed to packet socket's sendmsg() when doing a TX_RING flush run, then skb->protocol is set to po->num instead, which is the protocol passed via socket(2)/bind(2). Applications only xmitting can go the path of allocating the socket as socket(PF_PACKET, <mode>, 0) and do a bind(2) on the TX_RING with sll_protocol of 0. That way, register_prot_hook() is neither called on creation nor on bind time, which saves cycles when there's no interest in capturing anyway. That leaves us however with po->num 0 instead and therefore the TX_RING flush run sets skb->protocol to 0 as well. Eric reported that this leads to problems when using tools like trafgen over bonding device. I.e. the bonding's hash function could invoke the kernel's flow dissector, which depends on skb->protocol being properly set. In the current situation, all the traffic is then directed to a single slave. Fix it up by inferring skb->protocol from the Ethernet header when not set and we have ARPHRD_ETHER device type. This is only done in case of SOCK_RAW and where we have a dev->hard_header_len length. In case of ARPHRD_ETHER devices, this is guaranteed to cover ETH_HLEN, and therefore being accessed on the skb after the skb_store_bits(). Reported-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/packet/af_packet.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 8795b0fb1ed1..0066da2b8e44 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2338,6 +2338,15 @@ static bool ll_header_truncated(const struct net_device *dev, int len)
return false;
}
+static void tpacket_set_protocol(const struct net_device *dev,
+ struct sk_buff *skb)
+{
+ if (dev->type == ARPHRD_ETHER) {
+ skb_reset_mac_header(skb);
+ skb->protocol = eth_hdr(skb)->h_proto;
+ }
+}
+
static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb,
void *frame, struct net_device *dev, int size_max,
__be16 proto, unsigned char *addr, int hlen)
@@ -2419,6 +2428,8 @@ static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb,
dev->hard_header_len);
if (unlikely(err))
return err;
+ if (!skb->protocol)
+ tpacket_set_protocol(dev, skb);
data += dev->hard_header_len;
to_write -= dev->hard_header_len;