From: Stefan Metzmacher <[email protected]>
To: Pavel Begunkov <[email protected]>, 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: Wed, 29 Jan 2020 15:27:11 +0100 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
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Hi Pavel,
>>>>> @@ -3977,7 +3977,8 @@ static int io_req_defer_prep(struct io_kiocb *req,
>>>>> mmgrab(current->mm);
>>>>> req->work.mm = current->mm;
>>>>> }
>>>>> - req->work.creds = get_current_cred();
>>>>> + if (!req->work.creds)
>>>>> + req->work.creds = get_current_cred();
>>>>>
>>>>> switch (req->opcode) {
>>>>> case IORING_OP_NOP:
>>>>
>>>> The override_creds(personality_creds) has changed current->cred
>>>> and get_current_cred() will just pick it up as in the default case.
>>>>
>>>> This would make the patch much simpler and allows put_cred() to be
>>>> in io_put_work() instead of __io_req_aux_free() as explained above.
>>>>
>>>
>>> It's one extra get_current_cred(). I'd prefer to find another way to
>>> clean this up.
>>
>> As far as I can see it avoids a get_cred() in the IOSQE_PERSONALITY case
>> and the if (!req->work.creds) for both cases.
>
> Great, that you turned attention to that! override_creds() is already
> grabbing a ref, so it shouldn't call get_cred() there.
> So, that's a bug.
>
> It could be I'm wrong with the statement above, need to recheck all this
> code to be sure.
>
> BTW, io_req_defer_prep() may be called twice for a req, so you will
> reassign it without putting a ref. It's safer to leave NULL checks. At
> least, until I've done reworking and fixing preparation paths.
Ok, but that would be already a bug in
"io_uring/io-wq: don't use static creds/mm assignments"
instead of logically being part of
"io_uring: support using a registered personality for commands"
metze
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next prev parent reply other threads:[~2020-01-29 14:27 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
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 [this message]
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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