Re: [PATCH iproute2 6/9] actions: add skbmod action

On Sat,  1 Oct 2016 16:48:34 -0400
Jamal Hadi Salim [off-list ref] wrote:

From: Jamal Hadi Salim <jhs@mojatatu.com>

This action is intended to be an upgrade from a usability perspective
from pedit (as well as operational debugability).
Compare this:

sudo tc filter add dev $ETH parent 1: protocol ip prio 10 \
u32 match ip protocol 1 0xff flowid 1:2 \
action pedit munge offset -14 u8 set 0x02 \
    munge offset -13 u8 set 0x15 \
    munge offset -12 u8 set 0x15 \
    munge offset -11 u8 set 0x15 \
    munge offset -10 u16 set 0x1515 \
    pipe

to:

sudo tc filter add dev $ETH parent 1: protocol ip prio 10 \
u32 match ip protocol 1 0xff flowid 1:2 \
action skbmod dmac 02:15:15:15:15:15

Or worse, try to debug a policy with destination mac, source mac and
etherype. Then make that a hundred rules and you'll get my point.

The most important ethernet use case at the moment is when redirecting or
mirroring packets to a remote machine. The dst mac address needs a re-write
so that it doesnt get dropped or confuse an interconnecting (learning) switch
or dropped by a target machine (which looks at the dst mac).

In the future common use cases on pedit can be migrated to this action
(as an example different fields in ip v4/6, transports like tcp/udp/sctp
etc). For this first cut, this allows modifying basic ethernet header.

Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>

Lots of checkpatch errors on this. Please fix and resubmit series.
For example:

ERROR: spaces required around that '+=' (ctx:WxV)
#442: FILE: tc/m_skbmod.c:79:
+			ok +=1;


ERROR: code indent should use tabs where possible
#567: FILE: tc/m_skbmod.c:204:
+        SPRINT_BUF(b1);$

WARNING: please, no spaces at the start of a line
#567: FILE: tc/m_skbmod.c:204:
+        SPRINT_BUF(b1);$

ERROR: code indent should use tabs where possible
#568: FILE: tc/m_skbmod.c:205:
+        SPRINT_BUF(b2);$

WARNING: please, no spaces at the start of a line
#568: FILE: tc/m_skbmod.c:205:
+        SPRINT_BUF(b2);$

WARNING: braces {} are not necessary for single statement blocks
#610: FILE: tc/m_skbmod.c:247:
+	if (p->flags & SKBMOD_F_SWAPMAC) {
+		fprintf(f, "swap mac ");
+	}


ERROR: trailing whitespace
#816: FILE: man/man8/tc-skbmod.8:28:
+.IR CONTROL " := {"                                                             $