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author | Daniel Borkmann <daniel@iogearbox.net> | 2015-11-11 23:25:43 +0100 |
---|---|---|
committer | Luis Henriques <luis.henriques@canonical.com> | 2015-12-18 16:06:18 +0000 |
commit | d9850f8ef951bca36f1962c1570c3d6f01162316 (patch) | |
tree | 9cb7f27a86b8f288b33236d12030d2a9013df6b9 /net/packet | |
parent | 66a74d9654121cd7c2ea432f19bd682a12d96835 (diff) | |
download | linux-stable-d9850f8ef951bca36f1962c1570c3d6f01162316.tar.gz linux-stable-d9850f8ef951bca36f1962c1570c3d6f01162316.tar.bz2 linux-stable-d9850f8ef951bca36f1962c1570c3d6f01162316.zip |
packet: infer protocol from ethernet header if unset
commit c72219b75fde768efccf7666342282fab7f9e4e7 upstream.
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>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
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 e9ea7ff99bc0..b5c38ab3a93f 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2097,6 +2097,15 @@ static void tpacket_destruct_skb(struct sk_buff *skb) sock_wfree(skb); } +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) @@ -2182,6 +2191,8 @@ 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; |