Thanks for the reply. I've been hanging out for it!
On 19/05/14 23:31, Florian Westphal wrote:
Well, did you test what happens if we try to refrag a packet
containing ip options after the revert?
can happen e.g. when using netfilter conntrack on top of a bridge.
No. I expect it would panic, as was reported prior to the commit.
I tried to persevere with the commit: I recalculated checksum, which
left routes and times improperly updated in options. Then I tried
calling ip_forward_options, which looks like it would correctly update
RR and TS (not to mention checksum)m but that bombed because skb_rtable
returned NULL. I think calling skb_set_dst would answer that, but I
don't know how to get a valid dst. (I asked for help but no answer.)
I see three ways to progress:
1. Possibly call ip_forward_option, but that requires somebody who
understands this code to help;
2. Just recalculate the checksum, leaving crap in the options; or
3. Revert the commit.
Option 1 doesn't look like it's going to happen; option 2 is stupid;
leaving option 3, and I begin to think that's the right way to go if
bridge is supposed to be a bridge and not a router. The idea that
bridge is doing too much seems to have quite a lot of currency, so think
of reversion as chopping off a canker. Or we keep fixing bugs, adding
to bridge, until it replicates all of IP.
How does a packet get fragmented in this case? Does it only happen when
bridging to a device with smaller MTU? That scenario sounds quite
un-bridge-like. It also sounds like something that can be handled by
real routing.
