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author | Daniel Borkmann <daniel@iogearbox.net> | 2015-11-11 23:25:43 +0100 |
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committer | David S. Miller <davem@davemloft.net> | 2015-11-15 18:00:35 -0500 |
commit | c72219b75fde768efccf7666342282fab7f9e4e7 (patch) | |
tree | 5d58d422d2fb6349c8f68eedc578042cfc0efd9a /net/packet | |
parent | 3c70c132488794e2489ab045559b0ce0afcf17de (diff) | |
download | linux-c72219b75fde768efccf7666342282fab7f9e4e7.tar.gz linux-c72219b75fde768efccf7666342282fab7f9e4e7.tar.bz2 linux-c72219b75fde768efccf7666342282fab7f9e4e7.zip |
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/packet')
-rw-r--r-- | net/packet/af_packet.c | 11 |
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; |