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>
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 67bfac1..3b5d134 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1398,7 +1398,8 @@
* @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