Commit 880621c2 authored by Martin Blumenstingl's avatar Martin Blumenstingl Committed by David S. Miller

packet: Allow packets with only a header (but no payload)

Commit 9c707762 ("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: default avatarMartin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c9da161c
...@@ -1398,7 +1398,8 @@ enum netdev_priv_flags { ...@@ -1398,7 +1398,8 @@ enum netdev_priv_flags {
* @dma: DMA channel * @dma: DMA channel
* @mtu: Interface MTU value * @mtu: Interface MTU value
* @type: Interface hardware type * @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 * @needed_headroom: Extra headroom the hardware may need, but not in all
* cases can this be guaranteed * cases can this be guaranteed
......
...@@ -2329,8 +2329,8 @@ static void tpacket_destruct_skb(struct sk_buff *skb) ...@@ -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) static bool ll_header_truncated(const struct net_device *dev, int len)
{ {
/* net device doesn't like empty head */ /* net device doesn't like empty head */
if (unlikely(len <= dev->hard_header_len)) { if (unlikely(len < dev->hard_header_len)) {
net_warn_ratelimited("%s: packet size is too short (%d <= %d)\n", net_warn_ratelimited("%s: packet size is too short (%d < %d)\n",
current->comm, len, dev->hard_header_len); current->comm, len, dev->hard_header_len);
return true; return true;
} }
......
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