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authorMartin Blumenstingl <martin.blumenstingl@googlemail.com>2015-11-22 17:46:09 +0100
committerDavid S. Miller <davem@davemloft.net>2015-11-29 22:17:17 -0500
commit880621c2605b82eb5af91a2c94223df6f5a3fb64 (patch)
treeb1a1799ef943f2aa04d35530e47dae15282cb2ab
parentc9da161c6517ba12154059d3b965c2cbaf16f90f (diff)
packet: Allow packets with only a header (but no payload)
Commit 9c7077622dd91 ("packet: make packet_snd fail on len smaller than l2 header") added validation for the packet size in packet_snd. This change enforces that every packet needs a header (with at least hard_header_len bytes) plus a payload with at least one byte. Before this change the payload was optional. This fixes PPPoE connections which do not have a "Service" or "Host-Uniq" configured (which is violating the spec, but is still widely used in real-world setups). Those are currently failing with the following message: "pppd: packet size is too short (24 <= 24)" Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/linux/netdevice.h3
-rw-r--r--net/packet/af_packet.c4
2 files changed, 4 insertions, 3 deletions
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 67bfac1abfc1..3b5d134e945a 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1398,7 +1398,8 @@ enum netdev_priv_flags {
* @dma: DMA channel
* @mtu: Interface MTU value
* @type: Interface hardware type
- * @hard_header_len: Hardware header length
+ * @hard_header_len: Hardware header length, which means that this is the
+ * minimum size of a packet.
*
* @needed_headroom: Extra headroom the hardware may need, but not in all
* cases can this be guaranteed
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 1cf928fb573e..992396aa635c 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2329,8 +2329,8 @@ static void tpacket_destruct_skb(struct sk_buff *skb)
static bool ll_header_truncated(const struct net_device *dev, int len)
{
/* net device doesn't like empty head */
- if (unlikely(len <= dev->hard_header_len)) {
- net_warn_ratelimited("%s: packet size is too short (%d <= %d)\n",
+ if (unlikely(len < dev->hard_header_len)) {
+ net_warn_ratelimited("%s: packet size is too short (%d < %d)\n",
current->comm, len, dev->hard_header_len);
return true;
}