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From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Kees Cook <keescook@chromium.org>,
	Eric Biggers <ebiggers@google.com>,
	Gilad Ben-Yossef <gilad@benyossef.com>,
	Alexander Stein <alexander.stein@systec-electronic.com>,
	Antoine Tenart <antoine.tenart@bootlin.com>,
	Boris Brezillon <boris.brezillon@bootlin.com>,
	Arnaud Ebalard <arno@natisbad.org>,
	Corentin Labbe <clabbe.montjoie@gmail.com>,
	Maxime Ripard <maxime.ripard@bootlin.com>,
	Chen-Yu Tsai <wens@csie.org>,
	Christian Lamparter <chunkeey@gmail.com>,
	Philippe Ombredanne <pombredanne@nexb.com>,
	Jonathan Cameron <Jonathan.Cameron@huawei.com>,
	"open list:HARDWARE RANDOM NUMBER GENERATOR CORE"
	<linux-crypto@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v2 2/4] crypto: skcipher - Enforce non-ASYNC for on-stack requests
Date: Fri, 7 Sep 2018 08:56:23 +0200	[thread overview]
Message-ID: <CAKv+Gu9kHpBTKjQKA3W4Q424FeY+Zq4srq2-r0MxjfCNKHT_5A@mail.gmail.com> (raw)
In-Reply-To: <20180907034242.zhm4dglzkldhvh3x@gondor.apana.org.au>

On 7 September 2018 at 05:42, Herbert Xu <herbert@gondor.apana.org.au> wrote:
> On Thu, Sep 06, 2018 at 03:58:52PM -0700, Kees Cook wrote:
>>
>> @@ -437,6 +442,12 @@ static inline struct crypto_skcipher *crypto_skcipher_reqtfm_check(
>>  {
>>       struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
>>
>> +     if (req->__onstack) {
>> +             if (WARN_ON(crypto_skcipher_alg(tfm)->base.cra_flags &
>> +                             CRYPTO_ALG_ASYNC))
>> +                     return ERR_PTR(-EINVAL);
>> +     }
>
> Sorry but I don't like imposing a run-time check on everybody when
> stack-based requests are the odd ones out.  If we're going to make
> this a run-time check (I'd much prefer a compile-time check, but I
> understand that this may involve too much churn), then please do it
> for stack-based request users only.
>

OK, so given that all SKCIPHER_REQUEST_ON_STACK occurrences are
updated in this series anyway, perhaps we should add
skcipher_[en|de]crypt_onstack() flavors that encapsulate the
additional check? Only question is how to enforce at compile time that
those are used instead of the ordinary ones when using a stack
allocated request. Would you mind using some macro foo here involving
__builtin_types_compatible_p() ?

WARNING: multiple messages have this Message-ID (diff)
From: ard.biesheuvel@linaro.org (Ard Biesheuvel)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 2/4] crypto: skcipher - Enforce non-ASYNC for on-stack requests
Date: Fri, 7 Sep 2018 08:56:23 +0200	[thread overview]
Message-ID: <CAKv+Gu9kHpBTKjQKA3W4Q424FeY+Zq4srq2-r0MxjfCNKHT_5A@mail.gmail.com> (raw)
In-Reply-To: <20180907034242.zhm4dglzkldhvh3x@gondor.apana.org.au>

On 7 September 2018 at 05:42, Herbert Xu <herbert@gondor.apana.org.au> wrote:
> On Thu, Sep 06, 2018 at 03:58:52PM -0700, Kees Cook wrote:
>>
>> @@ -437,6 +442,12 @@ static inline struct crypto_skcipher *crypto_skcipher_reqtfm_check(
>>  {
>>       struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
>>
>> +     if (req->__onstack) {
>> +             if (WARN_ON(crypto_skcipher_alg(tfm)->base.cra_flags &
>> +                             CRYPTO_ALG_ASYNC))
>> +                     return ERR_PTR(-EINVAL);
>> +     }
>
> Sorry but I don't like imposing a run-time check on everybody when
> stack-based requests are the odd ones out.  If we're going to make
> this a run-time check (I'd much prefer a compile-time check, but I
> understand that this may involve too much churn), then please do it
> for stack-based request users only.
>

OK, so given that all SKCIPHER_REQUEST_ON_STACK occurrences are
updated in this series anyway, perhaps we should add
skcipher_[en|de]crypt_onstack() flavors that encapsulate the
additional check? Only question is how to enforce at compile time that
those are used instead of the ordinary ones when using a stack
allocated request. Would you mind using some macro foo here involving
__builtin_types_compatible_p() ?

  reply	other threads:[~2018-09-07  6:56 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-06 22:58 [PATCH v2 0/4] crypto: skcipher - Remove VLA usage Kees Cook
2018-09-06 22:58 ` Kees Cook
2018-09-06 22:58 ` [PATCH v2 1/4] crypto: skcipher - Consolidate encrypt/decrypt sanity check Kees Cook
2018-09-06 22:58   ` Kees Cook
2018-09-06 22:58 ` [PATCH v2 2/4] crypto: skcipher - Enforce non-ASYNC for on-stack requests Kees Cook
2018-09-06 22:58   ` Kees Cook
2018-09-07  3:42   ` Herbert Xu
2018-09-07  3:42     ` Herbert Xu
2018-09-07  6:56     ` Ard Biesheuvel [this message]
2018-09-07  6:56       ` Ard Biesheuvel
2018-09-07  6:56       ` Ard Biesheuvel
2018-09-11  5:52       ` Herbert Xu
2018-09-11  5:52         ` Herbert Xu
2018-09-11  5:52         ` Herbert Xu
2018-09-13 16:46         ` Kees Cook
2018-09-13 16:46           ` Kees Cook
2018-09-13 16:46           ` Kees Cook
2018-09-13 17:40           ` Kees Cook
2018-09-13 17:40             ` Kees Cook
2018-09-13 17:40             ` Kees Cook
2018-09-07 16:02     ` Kees Cook
2018-09-07 16:02       ` Kees Cook
2018-09-11  5:53       ` Herbert Xu
2018-09-11  5:53         ` Herbert Xu
2018-09-06 22:58 ` [PATCH v2 3/4] crypto: skcipher - Remove VLA usage for SKCIPHER_REQUEST_ON_STACK Kees Cook
2018-09-06 22:58   ` Kees Cook
2018-09-06 22:58 ` [PATCH 4/4] crypto: skcipher - Remove unused argument to SKCIPHER_REQUEST_ON_STACK() Kees Cook
2018-09-06 22:58   ` Kees Cook

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