From: Fernando Fernandez Mancera <ffmancera@riseup.net>
To: Phil Sutter <phil@nwl.cc>, Pablo Neira Ayuso <pablo@netfilter.org>
Cc: netfilter-devel@vger.kernel.org
Subject: Re: [PATCH nft v2 1/6] osf: add version fingerprint support
Date: Thu, 14 Mar 2019 19:24:23 +0100 [thread overview]
Message-ID: <27D82259-F921-48E0-A718-A08E2BCCAACD@riseup.net> (raw)
In-Reply-To: <20190314173454.GA19244@orbyte.nwl.cc>
El 14 de marzo de 2019 18:34:54 CET, Phil Sutter <phil@nwl.cc> escribió:
>Hi,
>
>On Thu, Mar 14, 2019 at 02:58:40PM +0100, Pablo Neira Ayuso wrote:
>> Hi,
>>
>> On Thu, Mar 14, 2019 at 12:14:23PM +0100, Fernando Fernandez Mancera
>wrote:
>> > Hi,
>> >
>> > I have been thinking more about this today. I don't know how access
>to
>> > the right-hand-side string from the kernel if it is possible. Sorry
>if
>> > the question is very dumb, but I may lack experience with the nft
>> > registers and RHS data of an expression.
>>
>> I think you can hide flags from json, which is what Phil suggests, I
>> mean, just infer version flags from the syntax, ie. if
>> "genre::version" is used, then set of the version flag.
>>
>> I think Phil is not suggesting kernel changes.
That makes sense to me.
>
>Actually I'm still in the process of understanding how all this works.
>What I got so far is (correct me if I'm wrong): osf expr does the
>fingerprinting and returns a string which relational expr compares to
>right-hand side. This new version flag defines whether osf expr adds
>the
>version to returned string or not.
>
Yes that is correct.
>Assuming the above is correct, my suggestion of making the flag option
>implicit does not quite hold, at least not without painful
>postprocessing of relational statement in userspace.
>
>Right now this all seems to me like enabling multiple comparisons
>within
>a single relational, i.e. one for genre and the other for version.
>Nftables doesn't quite do such things. E.g. matching on two TCP header
>fields requires two relationals, e.g. 'tcp dport 22 tcp sport > 1024'.
>Internally then, these two statements may be combined into a single
>payload match if suitable.
I think in this case we can't do that. In my opinion it doesn't make sense to evaluate only the version without the OS genre. Do you agree? Thanks!
>
>Applying the same logic to osf expression, we would implement 'osf name
>foo osf version 3.141' and add 'osf_try_merge()' routine to
>'rule_postprocess()' which tries to combine the two statements.
>Obviously, this is quite a bit of extra work, not sure if feasible.
>
>Cheers, Phil
next prev parent reply other threads:[~2019-03-14 18:24 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-11 15:14 [PATCH nft v2 1/6] osf: add version fingerprint support Fernando Fernandez Mancera
2019-03-11 15:14 ` [PATCH nft v2 2/6] json: osf: add version json support Fernando Fernandez Mancera
2019-03-11 15:14 ` [PATCH nft v2 3/6] tests: py: add osf tests with versions Fernando Fernandez Mancera
2019-03-11 15:14 ` [PATCH nft v2 4/6] doc: add osf version option to man page Fernando Fernandez Mancera
2019-03-11 15:14 ` [PATCH nft v2 5/6] files: osf: update pf.os with newer OS fingerprints Fernando Fernandez Mancera
2019-03-11 15:14 ` [PATCH nft v2 6/6] files: pf.os: merge the signatures spllited by version Fernando Fernandez Mancera
2019-03-13 9:44 ` [PATCH nft v2 1/6] osf: add version fingerprint support Phil Sutter
2019-03-13 10:14 ` Fernando Fernandez Mancera
2019-03-13 11:27 ` Phil Sutter
2019-03-13 14:15 ` Fernando Fernandez Mancera
2019-03-13 15:06 ` Phil Sutter
2019-03-13 15:22 ` Fernando Fernandez Mancera
2019-03-13 15:34 ` Phil Sutter
2019-03-13 16:46 ` Fernando Fernandez Mancera
2019-03-14 11:14 ` Fernando Fernandez Mancera
2019-03-14 13:58 ` Pablo Neira Ayuso
2019-03-14 17:34 ` Phil Sutter
2019-03-14 18:24 ` Fernando Fernandez Mancera [this message]
2019-03-15 10:03 ` Phil Sutter
2019-03-15 17:13 ` Pablo Neira Ayuso
2019-03-15 20:21 ` Fernando Fernandez Mancera
2019-03-16 9:05 ` Pablo Neira Ayuso
2019-03-17 17:10 ` Fernando Fernandez Mancera
2019-03-18 17:42 ` Phil Sutter
2019-03-19 11:06 ` Pablo Neira Ayuso
2019-03-20 13:46 ` Phil Sutter
2019-03-21 8:32 ` Pablo Neira Ayuso
2019-03-21 11:15 ` Phil Sutter
2019-03-21 11:18 ` Pablo Neira Ayuso
2019-03-21 14:06 ` Phil Sutter
2019-03-21 16:57 ` Pablo Neira Ayuso
2019-03-21 18:14 ` Phil Sutter
2019-03-14 20:07 ` Pablo Neira Ayuso
2019-03-14 20:13 ` [PATCH nft v2 1/6] osf: add version fingerprint supportg Pablo Neira Ayuso
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