netdev - Re: bpf pointer alignment validation

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Message-Id: <20170508.110412.1728647139242329068.davem@davemloft.net>
Date:   Mon, 08 May 2017 11:04:12 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     daniel@...earbox.net
Cc:     ast@...com, netdev@...r.kernel.org
Subject: Re: bpf pointer alignment validation

From: Daniel Borkmann <daniel@...earbox.net>
Date: Mon, 08 May 2017 12:49:25 +0200

> On 05/06/2017 04:47 AM, David Miller wrote:
>> From: David Miller <davem@...emloft.net>
>> Date: Fri, 05 May 2017 16:20:44 -0400 (EDT)
>>
>>> Anyways, I'll play with this design and see what happens...
>>> Feedback is of course welcome.
>>
>> Here is a prototype that works for me with test_pkt_access.c,
>> which otherwise won't load on sparc.
> 
> Code looks good to me as far as I can tell, thanks for working
> on this.
> 
> Could you also add test cases specifically to this for test_verifier
> in bpf selftests? I'm thinking of the cases when we have no pkt id
> and offset originated from reg->off (accumulated through const imm
> ops on reg) and insn->off, where we had i) no pkt id and ii) a
> specific pkt id (so we can probe for aux_off_align rejection as well).
> I believe we do have coverage to some extend in some of the tests
> (more on the map_value_adj though), but it would be good to keep
> tracking this specifically as well.

Yes, I am working on also on special tests that parse the verifier
trace to make sure the alignment values were calculated properly.