On Fri, Dec 31, 2004 at 12:10:48AM +0100, Bart De Schuymer wrote:

quoted

A while ago there were a number of problems with bridging CIPE ethernet
devices, which turned out to be the bridge code not initialising
skb->protocol for locally originated STP frames.

At the time I was told that initialising skb->protocol for locally
originated packets is required, so that is how I fixed it then.

Hi Lennert,

Hello,

skb->protocol is not set for locally generated packets when the packet
is still in the IP stack. I don't know what happens with it after the IP
stack is finished with the packet.
The comment in skbuff.h says "packet protocol from driver", from which I
tend to conclude that skb->protocol is only set by drivers when a packet
enters the box.
Too bad stuff like this isn't clearly spelled out,

This is what I thought back then too.  Indeed, it's rather misleading.

the FIXME for the dst field has been sitting there for probably more
than a year too.

Yes :(

Just one more thing: AFAIK it is possible to inject a raw IPv4 packet
with an invalid IPv4 header.  So maybe the better 'fix' would be to have
different hooks for PF_INET and PF_INET6, and distinguish v4/v6 packets
that way instead of peeking into the header.  (The hook you're talking
about is a PF_INET* and not a PF_BRIDGE hook, right?)

Then again, that would add yet another function onto the already rather
deep call chains that we have in there.

Too bad I don't see any cleaner way of integrating the whole bridging
thing into the stack.  I wonder if any of the *BSDs found a cleaner way
of doing this.


--L