K 10
svn:author
V 5
andre
K 8
svn:date
V 27
2012-11-19T18:04:17.794741Z
K 7
svn:log
V 1224
Convert IP, IPv6, UDP, TCP and SCTP to the new checksum offloading
semantics on the inbound and outbound path.

In short for inbound there are two levels the offloading NIC can
set:

 CSUM_L3_CALC	for an IP layer 3 checksum calculated by the NIC;
 CSUM_L3_VALID	set when the calculated checksum matches the one
		in the packet;
 CSUM_L4_CALC	for an UDP/TCP/SCTP layer 4 checksum calculated by
		the NIC;
 CSUM_L4_VALID	set when the calculated checksum matche the one
		in the packet.

From this follows that a packet failed checksum verification when
only *_CALC is set but not *_VALID.  The NIC is expected to deliver
a failed packet up the stack anyways for capture by BPF and to
record protocol specific checksum mismatch statistics.

The old approach with CSUM_DATA_VALID and CSUM_PSEUDO_HDR could not
signal a failed packet.  A failed packet was delivered into the stack
and the protocol had to recalculate the checksum for verification
every time to detect that as the absence of CSUM_DATA_VALID didn't
signal that the packet was broken.  It was only saying that the
checksum wasn't calculated by the NIC, which actually  wasn't the case.

Drag the other stack infrastructure, including packet filters, along
as well.

END