From: Leonard Crestez <cdleonard@gmail.com>
To: Eric Dumazet <edumazet@google.com>,
Herbert Xu <herbert@gondor.apana.org.au>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
Dmitry Safonov <0x7f454c46@gmail.com>,
David Ahern <dsahern@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
Kuniyuki Iwashima <kuniyu@amazon.co.jp>,
Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
Jakub Kicinski <kuba@kernel.org>,
Yuchung Cheng <ycheng@google.com>,
Francesco Ruggeri <fruggeri@arista.com>,
Mat Martineau <mathew.j.martineau@linux.intel.com>,
Christoph Paasch <cpaasch@apple.com>,
Ivan Delalande <colona@arista.com>,
Priyaranjan Jha <priyarjha@google.com>,
Menglong Dong <dong.menglong@zte.com.cn>,
netdev <netdev@vger.kernel.org>,
"open list:HARDWARE RANDOM NUMBER GENERATOR CORE"
<linux-crypto@vger.kernel.org>,
"open list:KERNEL SELFTEST FRAMEWORK"
<linux-kselftest@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Shuah Khan <shuah@kernel.org>
Subject: Re: [RFCv3 05/15] tcp: authopt: Add crypto initialization
Date: Wed, 25 Aug 2021 21:56:17 +0300 [thread overview]
Message-ID: <9ee51fc2-0b7e-4dc5-881b-9f6d671347ea@gmail.com> (raw)
In-Reply-To: <CANn89iJPyQpJTxrDMGszEOrgKwaEdYz1xaRK7vKbS4qj9tV23g@mail.gmail.com>
On 8/25/21 8:55 PM, Eric Dumazet wrote:
> On Wed, Aug 25, 2021 at 9:35 AM Leonard Crestez <cdleonard@gmail.com> wrote:
>>
>> On 25.08.2021 02:34, Eric Dumazet wrote:
>>> On 8/24/21 2:34 PM, Leonard Crestez wrote:
>>>> The crypto_shash API is used in order to compute packet signatures. The
>>>> API comes with several unfortunate limitations:
>>>>
>>>> 1) Allocating a crypto_shash can sleep and must be done in user context.
>>>> 2) Packet signatures must be computed in softirq context
>>>> 3) Packet signatures use dynamic "traffic keys" which require exclusive
>>>> access to crypto_shash for crypto_setkey.
>>>>
>>>> The solution is to allocate one crypto_shash for each possible cpu for
>>>> each algorithm at setsockopt time. The per-cpu tfm is then borrowed from
>>>> softirq context, signatures are computed and the tfm is returned.
>>>>
>>>
>>> I could not see the per-cpu stuff that you mention in the changelog.
>>
>> That's a little embarrasing, I forgot to implement the actual per-cpu
>> stuff. tcp_authopt_alg_imp.tfm is meant to be an array up to NR_CPUS and
>> tcp_authopt_alg_get_tfm needs no locking other than preempt_disable
>> (which should already be the case).
>
> Well, do not use arrays of NR_CPUS and instead use normal per_cpu
> accessors (as in __tcp_alloc_md5sig_pool)
>
>>
>> The reference counting would still only happen from very few places:
>> setsockopt, close and openreq. This would only impact request/response
>> traffic and relatively little.
>
> What I meant is that __tcp_alloc_md5sig_pool() allocates stuff one time,
> we do not care about tcp_md5sig_pool_populated going back to false.
>
> Otherwise, a single user application constantly allocating a socket,
> enabling MD5 (or authopt), then closing the socket would incur
> a big cost on hosts with a lot of cpus.
Allocating only once would definitely simply things.
I don't know if this might end up tying hardware resources forever if
some accelerators are in play but for this feature software-only crypto
is perfectly fine.
--
Regards,
Leonard
next prev parent reply other threads:[~2021-08-25 18:56 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-24 21:34 [RFCv3 00/15] tcp: Initial support for RFC5925 auth option Leonard Crestez
2021-08-24 21:34 ` [RFCv3 01/15] tcp: authopt: Initial support and key management Leonard Crestez
2021-08-31 19:04 ` Dmitry Safonov
2021-09-03 14:26 ` Leonard Crestez
2021-08-24 21:34 ` [RFCv3 02/15] docs: Add user documentation for tcp_authopt Leonard Crestez
2021-08-24 21:34 ` [RFCv3 03/15] selftests: Initial tcp_authopt test module Leonard Crestez
2021-08-24 21:34 ` [RFCv3 04/15] selftests: tcp_authopt: Initial sockopt manipulation Leonard Crestez
2021-08-24 21:34 ` [RFCv3 05/15] tcp: authopt: Add crypto initialization Leonard Crestez
2021-08-24 23:02 ` Eric Dumazet
2021-08-24 23:34 ` Eric Dumazet
2021-08-25 8:08 ` Herbert Xu
2021-08-25 14:55 ` Eric Dumazet
2021-08-25 16:04 ` Ard Biesheuvel
2021-08-25 16:31 ` Leonard Crestez
2021-08-25 16:35 ` Leonard Crestez
2021-08-25 17:55 ` Eric Dumazet
2021-08-25 18:56 ` Leonard Crestez [this message]
2021-08-24 21:34 ` [RFCv3 06/15] tcp: authopt: Compute packet signatures Leonard Crestez
2021-08-24 21:34 ` [RFCv3 07/15] tcp: authopt: Hook into tcp core Leonard Crestez
2021-08-24 22:59 ` Eric Dumazet
2021-08-25 16:32 ` Leonard Crestez
2021-08-24 21:34 ` [RFCv3 08/15] tcp: authopt: Add snmp counters Leonard Crestez
2021-08-24 21:34 ` [RFCv3 09/15] selftests: tcp_authopt: Test key address binding Leonard Crestez
2021-08-25 5:18 ` David Ahern
2021-08-25 16:37 ` Leonard Crestez
2021-08-24 21:34 ` [RFCv3 10/15] selftests: tcp_authopt: Capture and verify packets Leonard Crestez
2021-08-24 21:34 ` [RFCv3 11/15] selftests: Initial tcp_authopt support for nettest Leonard Crestez
2021-08-24 21:34 ` [RFCv3 12/15] selftests: Initial tcp_authopt support for fcnal-test Leonard Crestez
2021-08-24 21:34 ` [RFCv3 13/15] selftests: Add -t tcp_authopt option for fcnal-test.sh Leonard Crestez
2021-08-24 21:34 ` [RFCv3 14/15] tcp: authopt: Add key selection controls Leonard Crestez
2021-08-24 21:34 ` [RFCv3 15/15] selftests: tcp_authopt: Add tests for rollover Leonard Crestez
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=9ee51fc2-0b7e-4dc5-881b-9f6d671347ea@gmail.com \
--to=cdleonard@gmail.com \
--cc=0x7f454c46@gmail.com \
--cc=colona@arista.com \
--cc=cpaasch@apple.com \
--cc=davem@davemloft.net \
--cc=dong.menglong@zte.com.cn \
--cc=dsahern@kernel.org \
--cc=edumazet@google.com \
--cc=eric.dumazet@gmail.com \
--cc=fruggeri@arista.com \
--cc=herbert@gondor.apana.org.au \
--cc=kuba@kernel.org \
--cc=kuniyu@amazon.co.jp \
--cc=linux-crypto@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-kselftest@vger.kernel.org \
--cc=mathew.j.martineau@linux.intel.com \
--cc=netdev@vger.kernel.org \
--cc=priyarjha@google.com \
--cc=shuah@kernel.org \
--cc=ycheng@google.com \
--cc=yoshfuji@linux-ipv6.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).