Kurt Kanzenbach <k...@linutronix.de> writes:
> @@ -329,30 +327,14 @@ static int mlxsw_sp_ptp_parse(struct sk_buff *skb,
> return -ERANGE;
> }
>
> - if (ptp_class & PTP_CLASS_VLAN)
> - offset += VLAN_HLEN;
> -
> - switch (ptp_class & PTP_CLASS_PMASK) {
> - case PTP_CLASS_IPV4:
> - offset += ETH_HLEN + IPV4_HLEN(data + offset) + UDP_HLEN;
> - break;
> - case PTP_CLASS_IPV6:
> - offset += ETH_HLEN + IP6_HLEN + UDP_HLEN;
> - break;
> - case PTP_CLASS_L2:
> - offset += ETH_HLEN;
> - break;
> - default:
> - return -ERANGE;
> - }
> -
> - /* PTP header is 34 bytes. */
> - if (skb->len < offset + 34)
> + hdr = ptp_parse_header(skb, ptp_class);
> + if (!hdr)
> return -EINVAL;
So this looks good, and works, but I'm wondering about one thing.
Your code (and evidently most drivers as well) use a different check
than mlxsw, namely skb->len + ETH_HLEN < X. When I print_hex_dump()
skb_mac_header(skb), skb->len in mlxsw with some test packet, I get e.g.
this:
00000000259a4db7: 01 00 5e 00 01 81 00 02 c9 a4 e4 e1 08 00 45 00
..^...........E.
000000005f29f0eb: 00 48 0d c9 40 00 01 11 c8 59 c0 00 02 01 e0 00
.H..@....Y......
00000000f3663e9e: 01 81 01 3f 01 3f 00 34 9f d3 00 02 00 2c 00 00
...?.?.4.....,..
^sp^^ ^dp^^ ^len^ ^cks^ ^len^
00000000b3914606: 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 02
................
000000002e7828ea: c9 ff fe a4 e4 e1 00 01 09 fa 00 00 00 00 00 00
................
000000000b98156e: 00 00 00 00 00 00 ......
Both UDP and PTP length fields indicate that the payload ends exactly at
the end of the dump. So apparently skb->len contains all the payload
bytes, including the Ethernet header.
Is that the case for other drivers as well? Maybe mlxsw is just missing
some SKB magic in the driver.
