linux-kernel - Re: [PATCH v6 1/5] random: Blocking API for accessing nonblocking

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Message-ID: <6511355.kQJsTdtLzf@tachyon.chronox.de>
Date:	Tue, 19 May 2015 07:58:25 +0200
From:	Stephan Mueller <smueller@...onox.de>
To:	Theodore Ts'o <tytso@....edu>,
	Herbert Xu <herbert@...dor.apana.org.au>
Cc:	pebolle@...cali.nl, andreas.steffen@...ongswan.org,
	sandyinchina@...il.com, linux-kernel@...r.kernel.org,
	linux-crypto@...r.kernel.org
Subject: Re: [PATCH v6 1/5] random: Blocking API for accessing nonblocking_pool

Am Montag, 18. Mai 2015, 11:02:34 schrieb Theodore Ts'o:

Hi Theodore, Herbert,
> 
> The simplest thing to do is to put a refcount on inside the DRBG
> handle structure.  The caller instantiates the DRBG handle, and
> invokes the the DRBG.  The DRBG, since it is kicking off an
> asynchronous operation, increments the refcount.

That is a good idea. After experimenting with the refcount, I see that kernel 
crypto API release function of crypto_destroy_tfm unconditionally destroys the 
crypto handle by freeing it.

So, if a caller releases the DRBG handle, the DRBG code cannot prevent the 
destruction of its context with a refcount.

Herbert, do you have any ideas?

-- 
Ciao
Stephan
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