[Swan-dev] WIP: supporting xfrm SA expire

[Andrew Cagney]

>
>
>>
>> One thing decide as group is how to represent big number (2^64) bytes and
>> packets, especially the default 2^64  will appear in "ipsec status:
>> output.
>>  18446744073709551615 look ugly:)
>
>
> There's readable_humber() but that would need work.
> Conversely is there something to convert things like 100gb back to bytes.
>

and of course long after the code was written, the suffixes were
standardised by IEC et.al. ('99) and we're now meant to use GiB et.al.
https://en.wikipedia.org/wiki/Binary_prefix :-)


>
>>
>>
>> tests that log "ipsec status" output will get a diff:
>>
>> -000 "west":   ike_life: 28800s; ipsec_life: 28800s; replay_window: 128;
>> rekey_margin: 540s; rekey_fuzz: 100%; keyingtries: 0;
>> +000 "west":   ike_life: 28800s; ipsec_life: 28800s; replay_window: 128;
>> rekey_margin: 540s; rekey_fuzz: 100%; ipsec_life_bytes
>> 18446744073709551615;
>> ipsec_life_packets 18446744073709551615; keyingtries: 0;
>>
>> I see three choices to represent 18446744073709551615.
>>
>> 1.  ipsec_life_bytes: 2^64;
>>
>> 2. ipsec_life_bytes: 18E( it is 18.4467441 Exabytes)  18E would be an
>> approximation.
>>
>> 3. ipsec_life_bytes: INF
>> "ip xfrm state" output use INF to represet 2^64.
>> e.g "limit: soft (INF)(packets), hard (INF)(packets)"
>>
>> any preferences?
>>
>> regards,
>> -antony
>>
>> On Tue, Apr 06, 2021 at 02:38:08PM -0400, Paul Wouters wrote:
>> > On Tue, 6 Apr 2021, Antony Antony wrote:
>> >
>> > > > I noticed you used salifebytes= and salifepackets=. I think it
>> would be
>> > > > more intuitive to call these maxbytes= and maxpackets. Or
>> limit-bytes=
>> > > > or bytelimit= and packet-limit= ?
>> > >
>> > > given that we have "salifetime" for IPsec and "lifetime" from IKE
>> > > I feel life* would be better choce, so I choose salifebytes
>> salifepackets.
>> >
>> > Yes, it makes sense as a consistent choice. I'm just trying to think of
>> > the meaning of things for mortal end users :)
>> >
>> > > My next proposals are "rekey-bytes" and "rekey-packets". Those would
>> align
>> >
>> > But rekey might not be the action. But it does show better than "maxFOO"
>> > to explain what will happen. So I also understand why those terms were
>> > used by them.
>> >
>> > > > those maximums could just be hardcoded to a much lower count and
>> might
>> > > > never need to be user configurable? Like wouldn't 1Gbyte of IKE
>> > > > traffic be a good time to re-auth or rekey-with-pfs ? In which case
>> it
>> > >
>> > > well with Post Quantuam and PCPU I can imagine conerns abou IKE rekey
>> on the
>> > > horizon.
>> >
>> > We already have this formally with FIPS requirements. Sure, I don't
>> > think it is realistic to ever reach 2^16 IKE bytes, but we have to
>> > rekey before that happens :)
>> >
>> > I know I added code a long time ago to check the number of IKE bytes
>> > that have happened, but I don't think we act on it. We expect you would
>> > see issues with 2^16 IKE bytes in 1h (or since recently, 8h)
>> >
>> > > > might make sense to omit the "sa" prefix for the regular admin?
>> > >
>> > > again, what about "salifetime" are you going change that.
>> >
>> > the word "lifetime" is an english word. It suggests a start and end of
>> > life. It suggests a unit of time. But lifepackets or lifebytes does not
>> > exist as english word. As for the "sa" prefix, no other IPsec SA
>> > options have this prefix. It is usually clear from the context if it
>> > relates to IKE or IPsec. The lifetime/salifetime/ikelifeime was so
>> > far the only one that applied to both.
>> >
>> > Anyway, if we can't come up with better names, salifebytes/salifepackets
>> > will do.
>> >
>> > > > I'm glad to see you decided on configuring soft timeouts at a fixed
>> (80%)
>> > > > rate of hard limits. I was also hoping to not have an option for
>> this.
>> > >
>> > > I did it because I am lazy to code! I am not proud of it. I hope that
>> one
>> > > day we will support soft and hard limits. I clearly see benfits of the
>> > > flexibilty. Especially if we want to be more of reference
>> implementation.
>> >
>> > I'm still trying to not give users more options then needed. Yes, it is
>> > cheap to add soft/hard variant keywords and to set it for the kernel.
>> > But hard limits are things that a properly configured system should
>> > never reach, and an admin should never need to think about what soft
>> > limit they need to set with enough safety margin to avoid hitting the
>> > specified hard limit.
>> >
>> > > At the moment I am only looking for test case PR. That is my work
>> flow at
>> > > the moment! I just noticed you send a PR with tests I will see what I
>> can
>> > > pickup. Thanks.
>> >
>> > Feel free to close the PR if it does not work for you.
>> >
>> > I'll continue working on my branch on code and testing. Feel free to
>> > pick up only testing commits. They will always be seperate from code
>> > commits.
>> >
>> > Paul
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>>
>
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