packet: fix tpacket_snd max frame len
Since it's introduction in commit 69e3c75f4d54 ("net: TX_RING and
packet mmap"), TX_RING could be used from SOCK_DGRAM and SOCK_RAW
side. When used with SOCK_DGRAM only, the size_max > dev->mtu +
reserve check should have reserve as 0, but currently, this is
unconditionally set (in it's original form as dev->hard_header_len).
I think this is not correct since tpacket_fill_skb() would then
take dev->mtu and dev->hard_header_len into account for SOCK_DGRAM,
the extra VLAN_HLEN could be possible in both cases. Presumably, the
reserve code was copied from packet_snd(), but later on missed the
check. Make it similar as we have it in packet_snd().
Fixes: 69e3c75f4d54 ("net: TX_RING and packet mmap")
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>
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 0066da2..242bce1 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2510,12 +2510,13 @@
if (unlikely(!(dev->flags & IFF_UP)))
goto out_put;
- reserve = dev->hard_header_len + VLAN_HLEN;
+ if (po->sk.sk_socket->type == SOCK_RAW)
+ reserve = dev->hard_header_len;
size_max = po->tx_ring.frame_size
- (po->tp_hdrlen - sizeof(struct sockaddr_ll));
- if (size_max > dev->mtu + reserve)
- size_max = dev->mtu + reserve;
+ if (size_max > dev->mtu + reserve + VLAN_HLEN)
+ size_max = dev->mtu + reserve + VLAN_HLEN;
do {
ph = packet_current_frame(po, &po->tx_ring,
@@ -2542,7 +2543,7 @@
tp_len = tpacket_fill_skb(po, skb, ph, dev, size_max, proto,
addr, hlen);
if (likely(tp_len >= 0) &&
- tp_len > dev->mtu + dev->hard_header_len &&
+ tp_len > dev->mtu + reserve &&
!packet_extra_vlan_len_allowed(dev, skb))
tp_len = -EMSGSIZE;