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From: Daniel Borkmann <daniel@iogearbox.net>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>,
	Netdev <netdev@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
	"Jason A. Donenfeld" <Jason@zx2c4.com>,
	Hannes Frederic Sowa <hannes@stressinduktion.org>,
	Alexei Starovoitov <alexei.starovoitov@gmail.com>,
	Eric Dumazet <edumazet@google.com>,
	Eric Biggers <ebiggers3@gmail.com>,
	Tom Herbert <tom@herbertland.com>,
	"David S. Miller" <davem@davemloft.net>,
	Alexei Starovoitov <ast@kernel.org>
Subject: Re: [PATCH v2 7/8] net: Rename TCA*BPF_DIGEST to ..._SHA256
Date: Sat, 14 Jan 2017 00:08:30 +0100	[thread overview]
Message-ID: <58795DEE.3090403@iogearbox.net> (raw)
In-Reply-To: <CALCETrVhuszdsfayLrBBkSzJ+A3m+hJjdZQWDj9FOg+2UB_ZBw@mail.gmail.com>

On 01/11/2017 07:19 PM, Andy Lutomirski wrote:
> On Wed, Jan 11, 2017 at 1:09 AM, Daniel Borkmann <daniel@iogearbox.net> wrote:
[...]
>> Ok. Sleeping over this a bit, how about a general rename into
>> "prog_tag" for fdinfo and TCA_BPF_TAG resp. TCA_ACT_BPF_TAG for
>> the netlink attributes, fwiw, it might reduce any assumptions on
>> this being made? If this would be preferable, I could cook that
>> patch against -net for renaming it?
>
> That would be fine with me.
>
> I think there are two reasonable approaches to computing the actual tag.
>
> 1. Use a standard, modern cryptographic hash.  SHA-256, SHA-512,
> Blake2b, whatever.  SHA-1 is a bad choice in part because it's partly
> broken and in part because the implementation in lib/ is a real mess
> to use (as you noticed while writing the code).
>
> 2. Use whatever algorithm you like but make the tag so short that it's
> obviously not collision-free.  48 or 64 bits is probably reasonable.
>
> The intermediate versions are just asking for trouble.

Yeah agree, I've just sent a patch to rework this a bit and it got
also reasonably small for net. Cleanups, if needed, can be done in
net-next once that's pulled into it.

Thanks,
Daniel

  reply	other threads:[~2017-01-13 23:08 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-01-10 23:24 [PATCH v2 0/8] Switch BPF's digest to SHA256 Andy Lutomirski
2017-01-10 23:24 ` [PATCH v2 1/8] crypto/sha256: Factor out the parts of base API that don't use shash_desc Andy Lutomirski
2017-01-10 23:24 ` [PATCH v2 2/8] crypto/sha256: Export a sha256_{init,update,final}_direct() API Andy Lutomirski
2017-01-10 23:24 ` [PATCH v2 3/8] crypto/sha256: Build the SHA256 core separately from the crypto module Andy Lutomirski
2017-01-10 23:24 ` [PATCH v2 4/8] bpf: Use SHA256 instead of SHA1 for bpf digests Andy Lutomirski
2017-01-10 23:24 ` [PATCH v2 5/8] bpf: Avoid copying the entire BPF program when hashing it Andy Lutomirski
2017-01-10 23:24 ` [PATCH v2 6/8] bpf: Rename fdinfo's prog_digest to prog_sha256 Andy Lutomirski
2017-01-10 23:24 ` [PATCH v2 7/8] net: Rename TCA*BPF_DIGEST to ..._SHA256 Andy Lutomirski
2017-01-11  0:50   ` Daniel Borkmann
2017-01-11  3:11     ` Andy Lutomirski
2017-01-11  9:09       ` Daniel Borkmann
2017-01-11 18:19         ` Andy Lutomirski
2017-01-13 23:08           ` Daniel Borkmann [this message]
2017-01-10 23:24 ` [PATCH v2 8/8] crypto/testmgr: Allocate only the required output size for hash tests Andy Lutomirski
2017-01-11 15:13   ` David Laight
2017-01-11 18:10     ` Andy Lutomirski
2017-01-12  7:47   ` Herbert Xu
2017-01-12  7:52     ` Andy Lutomirski
2017-01-12 16:44   ` Herbert Xu
2017-01-11  1:09 ` [PATCH v2 0/8] Switch BPF's digest to SHA256 Alexei Starovoitov

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