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authorDaniel Borkmann <dborkman@redhat.com>2014-02-28 02:22:06 +0100
committerDavid S. Miller <davem@davemloft.net>2014-02-28 16:52:02 -0500
commit52f1454f629fafbfb47ad6727e0837250e1f08c0 (patch)
tree2d14ee6d76845c7b32bd8ce64a5928feea66cd06 /net/packet
parent07cb1c175e45b649daff5ec46012934904b8b07e (diff)
packet: allow to transmit +4 byte in TX_RING slot for VLAN case
Commit 57f89bfa2140 ("network: Allow af_packet to transmit +4 bytes for VLAN packets.") added the possibility for non-mmaped frames to send extra 4 byte for VLAN header so the MTU increases from 1500 to 1504 byte, for example. Commit cbd89acb9eb2 ("af_packet: fix for sending VLAN frames via packet_mmap") attempted to fix that for the mmap part but was reverted as it caused regressions while using eth_type_trans() on output path. Lets just act analogous to 57f89bfa2140 and add a similar logic to TX_RING. We presume size_max as overcharged with +4 bytes and later on after skb has been built by tpacket_fill_skb() check for ETH_P_8021Q header on packets larger than normal MTU. Can be easily reproduced with a slightly modified trafgen in mmap(2) mode, test cases: { fill(0xff, 12) const16(0x8100) fill(0xff, <1504|1505>) } { fill(0xff, 12) const16(0x0806) fill(0xff, <1500|1501>) } Note that we need to do the test right after tpacket_fill_skb() as sockets can have PACKET_LOSS set where we would not fail but instead just continue to traverse the ring. Reported-by: Mathias Kretschmer <mathias.kretschmer@fokus.fraunhofer.de> Signed-off-by: Daniel Borkmann <dborkman@redhat.com> Cc: Ben Greear <greearb@candelatech.com> Cc: Phil Sutter <phil@nwl.cc> Tested-by: Mathias Kretschmer <mathias.kretschmer@fokus.fraunhofer.de> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/packet')
-rw-r--r--net/packet/af_packet.c16
1 files changed, 13 insertions, 3 deletions
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 48a6a93db29..292304404fd 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2257,8 +2257,7 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
if (unlikely(!(dev->flags & IFF_UP)))
goto out_put;
- reserve = dev->hard_header_len;
-
+ reserve = dev->hard_header_len + VLAN_HLEN;
size_max = po->tx_ring.frame_size
- (po->tp_hdrlen - sizeof(struct sockaddr_ll));
@@ -2285,8 +2284,19 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
goto out_status;
tp_len = tpacket_fill_skb(po, skb, ph, dev, size_max, proto,
- addr, hlen);
+ addr, hlen);
+ if (tp_len > dev->mtu + dev->hard_header_len) {
+ struct ethhdr *ehdr;
+ /* Earlier code assumed this would be a VLAN pkt,
+ * double-check this now that we have the actual
+ * packet in hand.
+ */
+ skb_reset_mac_header(skb);
+ ehdr = eth_hdr(skb);
+ if (ehdr->h_proto != htons(ETH_P_8021Q))
+ tp_len = -EMSGSIZE;
+ }
if (unlikely(tp_len < 0)) {
if (po->tp_loss) {
__packet_set_status(po, ph,