From: Stefan Metzmacher <[email protected]>
To: Jens Axboe <[email protected]>
Cc: io-uring <[email protected]>,
Linux API Mailing List <[email protected]>
Subject: Re: IORING_REGISTER_CREDS[_UPDATE]() and credfd_create()?
Date: Tue, 28 Jan 2020 17:17:13 +0100 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
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Am 28.01.20 um 17:10 schrieb Jens Axboe:
> On 1/28/20 3:18 AM, Stefan Metzmacher wrote:
>> Hi Jens,
>>
>> now that we have IORING_FEAT_CUR_PERSONALITY...
>>
>> How can we optimize the fileserver case now, in order to avoid the
>> overhead of always calling 5 syscalls before io_uring_enter()?:
>>
>> /* gain root again */
>> setresuid(-1,0,-1); setresgid(-1,0,-1)
>> /* impersonate the user with groups */
>> setgroups(num, grps); setresgid(-1,gid,-1); setresuid(-1,uid,-1);
>> /* trigger the operation */
>> io_uring_enter();
>>
>> I guess some kind of IORING_REGISTER_CREDS[_UPDATE] would be
>> good, together with a IOSQE_FIXED_CREDS in order to specify
>> credentials per operation.
>>
>> Or we make it much more generic and introduce a credsfd_create()
>> syscall in order to get an fd for a credential handle, maybe
>> together with another syscall to activate the credentials of
>> the current thread (or let a write to the fd trigger the activation
>> in order to avoid an additional syscall number).
>>
>> Having just an fd would allow IORING_REGISTER_CREDS[_UPDATE]
>> to be just an array of int values instead of a more complex
>> structure to define the credentials.
>
> I'd rather avoid having to add more infrastructure for this, even if
> credsfd_create() would be nifty.
>
> With that in mind, something like:
>
> - Application does IORING_REGISTER_CREDS, which returns some index
>
> - Add a IORING_OP_USE_CREDS opcode, which sets the creds associated
> with dependent commands
> - Actual request is linked to the IORING_OP_USE_CREDS command, any
> link off IORING_OP_USE_CREDS will use those credentials
Using links for this sounds ok.
> - IORING_UNREGISTER_CREDS removes the registered creds
>
> Just throwing that out there, definitely willing to entertain other
> methods that make sense for this. Trying to avoid needing to put this
> information in the SQE itself, hence the idea to use a chain of links
> for it.
>
> The downside is that we'll need to maintain an array of key -> creds,
> but that's probably not a big deal.
>
> What do you think?
So IORING_REGISTER_CREDS would be a simple operation that just takes a
snapshot of the current_cred() and returns an id that can be passed to
IORING_OP_USE_CREDS or IORING_UNREGISTER_CREDS?
> Ideally I'd like to get this done for 5.6 even if we
> are a bit late, so you'll have everything you need with that release.
That would be great!
Thanks!
metze
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next prev parent reply other threads:[~2020-01-28 16:17 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-28 10:18 IORING_REGISTER_CREDS[_UPDATE]() and credfd_create()? Stefan Metzmacher
2020-01-28 16:10 ` Jens Axboe
2020-01-28 16:17 ` Stefan Metzmacher [this message]
2020-01-28 16:19 ` Jens Axboe
2020-01-28 17:19 ` Jens Axboe
2020-01-28 18:04 ` Jens Axboe
2020-01-28 19:42 ` Jens Axboe
2020-01-28 20:16 ` Pavel Begunkov
2020-01-28 20:19 ` Jens Axboe
2020-01-28 20:50 ` Pavel Begunkov
2020-01-28 20:56 ` Jens Axboe
2020-01-28 21:25 ` Christian Brauner
2020-01-28 22:38 ` Pavel Begunkov
2020-01-28 23:36 ` Pavel Begunkov
2020-01-28 23:40 ` Jens Axboe
2020-01-28 23:51 ` Jens Axboe
2020-01-29 0:10 ` Pavel Begunkov
2020-01-29 0:15 ` Jens Axboe
2020-01-29 0:18 ` Jens Axboe
2020-01-29 0:20 ` Jens Axboe
2020-01-29 0:21 ` Pavel Begunkov
2020-01-29 0:24 ` Jens Axboe
2020-01-29 0:54 ` Jens Axboe
2020-01-29 10:17 ` Pavel Begunkov
2020-01-29 13:11 ` Stefan Metzmacher
2020-01-29 13:41 ` Pavel Begunkov
2020-01-29 13:56 ` Stefan Metzmacher
2020-01-29 14:23 ` Pavel Begunkov
2020-01-29 14:27 ` Stefan Metzmacher
2020-01-29 14:34 ` Pavel Begunkov
2020-01-29 17:34 ` Jens Axboe
2020-01-29 17:42 ` Jens Axboe
2020-01-29 20:09 ` Stefan Metzmacher
2020-01-29 20:48 ` Jens Axboe
2020-01-29 17:46 ` Pavel Begunkov
2020-01-29 14:59 ` Jann Horn
2020-01-29 17:34 ` Jens Axboe
2020-01-30 1:08 ` Jens Axboe
2020-01-30 2:20 ` Jens Axboe
2020-01-30 3:18 ` Jens Axboe
2020-01-30 6:53 ` Stefan Metzmacher
2020-01-30 10:11 ` Jann Horn
2020-01-30 10:26 ` Christian Brauner
2020-01-30 14:11 ` Jens Axboe
2020-01-30 14:47 ` Stefan Metzmacher
2020-01-30 15:34 ` Jens Axboe
2020-01-30 15:13 ` Christian Brauner
2020-01-30 15:29 ` Jens Axboe
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