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Re: [PATCH v2] crypto: algif_skcipher - Require setkey before accept(2)

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On 01/02/2016 12:52 PM, Milan Broz wrote:
> On 12/25/2015 08:40 AM, Herbert Xu wrote:
>> Dmitry Vyukov <dvyukov@google.com> wrote:
>>>
>>> I am testing with your two patches:
>>> crypto: algif_skcipher - Use new skcipher interface
>>> crypto: algif_skcipher - Require setkey before accept(2)
>>> on top of a88164345b81292b55a8d4829fdd35c8d611cd7d (Dec 23).
>>
>> You sent the email to everyone on the original CC list except me.
>> Please don't do that.
>>
>>> Now the following program causes a bunch of use-after-frees and them
>>> kills kernel:
>>
>> Yes there is an obvious bug in the patch that Julia Lawall has
>> responded to in another thread.  Here is a fixed version.
>>
>> ---8<--
>> Some cipher implementations will crash if you try to use them
>> without calling setkey first.  This patch adds a check so that
>> the accept(2) call will fail with -ENOKEY if setkey hasn't been
>> done on the socket yet.
> 
> 
> Hi Herbert,
> 
> this patch breaks userspace in cryptsetup...
> 
> We use algif_skcipher in cryptsetup (for years, even before
> there was Stephan's library) and with this patch applied
> I see fail in ALG_SET_IV call (patch from your git).

(Obviously this was because of failing accept() call here, not set_iv.)

> 
> I can fix it upstream, but for thousands of installations it will
> be broken (for LUKS there is a fallback, cor TrueCrypt compatible devices
> it will be unusable. Also people who configured kernel crypto API as default
> backend will have non-working cryptsetup).
> 
> Is it really thing for stable branch?

Also how it is supposed to work for cipher_null, where there is no key?
Why it should call set_key if it is noop? (and set key length 0 is not possible).

(We are using cipher_null for testing and for offline re-encryption tool
to create temporary "fake" header for not-yet encrypted device...)

Milan

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Thread

GPF in lrw_crypt Dmitry Vyukov <dvyukov@google.com> - 2015-12-17 14:00 +0100
  Re: GPF in lrw_crypt Stephan Mueller <smueller@chronox.de> - 2015-12-22 00:00 +0100
  Re: GPF in lrw_crypt Herbert Xu <herbert@gondor.apana.org.au> - 2015-12-24 10:40 +0100
    Re: GPF in lrw_crypt Dmitry Vyukov <dvyukov@google.com> - 2015-12-24 12:10 +0100
      [PATCH v2] crypto: algif_skcipher - Require setkey before accept(2) Herbert Xu <herbert@gondor.apana.org.au> - 2015-12-25 08:50 +0100
        Re: [PATCH v2] crypto: algif_skcipher - Require setkey before accept(2) Dmitry Vyukov <dvyukov@google.com> - 2015-12-28 14:50 +0100
          Re: [PATCH v2] crypto: algif_skcipher - Require setkey before  accept(2) Herbert Xu <herbert@gondor.apana.org.au> - 2015-12-29 14:30 +0100
        Re: [PATCH v2] crypto: algif_skcipher - Require setkey before  accept(2) Milan Broz <gmazyland@gmail.com> - 2016-01-02 13:00 +0100
          Re: [PATCH v2] crypto: algif_skcipher - Require setkey before  accept(2) Milan Broz <gmazyland@gmail.com> - 2016-01-02 15:50 +0100
            Re: [PATCH v2] crypto: algif_skcipher - Require setkey before accept(2) Stephan Mueller <smueller@chronox.de> - 2016-01-02 21:10 +0100
              Re: [PATCH v2] crypto: algif_skcipher - Require setkey before  accept(2) Milan Broz <gmazyland@gmail.com> - 2016-01-02 21:20 +0100
                Re: [PATCH v2] crypto: algif_skcipher - Require setkey before  accept(2) Herbert Xu <herbert@gondor.apana.org.au> - 2016-01-03 02:40 +0100
                Re: [PATCH v2] crypto: algif_skcipher - Require setkey before  accept(2) Milan Broz <gmazyland@gmail.com> - 2016-01-03 10:50 +0100
                [PATCH 1/2] crypto: af_alg - Add nokey compatibility path Herbert Xu <herbert@gondor.apana.org.au> - 2016-01-04 05:40 +0100
                [PATCH 2/2] crypto: algif_skcipher - Add nokey compatibility path Herbert Xu <herbert@gondor.apana.org.au> - 2016-01-04 05:40 +0100
                Re: [PATCH 1/2] crypto: af_alg - Add nokey compatibility path Milan Broz <gmazyland@gmail.com> - 2016-01-04 13:40 +0100
                Re: [PATCH 1/2] crypto: af_alg - Add nokey compatibility path Herbert Xu <herbert@gondor.apana.org.au> - 2016-01-08 13:50 +0100
                Re: [PATCH 1/2] crypto: af_alg - Add nokey compatibility path Milan Broz <gmazyland@gmail.com> - 2016-01-08 19:30 +0100
                Re: [PATCH 1/2] crypto: af_alg - Add nokey compatibility path Herbert Xu <herbert@gondor.apana.org.au> - 2016-01-09 06:50 +0100
                Re: [PATCH 1/2] crypto: af_alg - Add nokey compatibility path Milan Broz <gmazyland@gmail.com> - 2016-01-09 11:20 +0100
                [PATCH 1/2] crypto: skcipher - Add crypto_skcipher_has_setkey Herbert Xu <herbert@gondor.apana.org.au> - 2016-01-11 14:30 +0100
                [PATCH 2/2] crypto: algif_skcipher - Add key check exception for  cipher_null Herbert Xu <herbert@gondor.apana.org.au> - 2016-01-11 14:40 +0100
                Re: [PATCH 2/2] crypto: algif_skcipher - Add key check exception for  cipher_null Milan Broz <gmazyland@gmail.com> - 2016-01-11 16:00 +0100
                [PATCH 1/2] crypto: hash - Add crypto_ahash_has_setkey Herbert Xu <herbert@gondor.apana.org.au> - 2016-01-08 14:30 +0100
                [PATCH 2/2] crypto: algif_hash - Require setkey before accept(2) Herbert Xu <herbert@gondor.apana.org.au> - 2016-01-08 14:40 +0100
                Re: [PATCH 2/2] crypto: algif_hash - Require setkey before accept(2) kbuild test robot <lkp@intel.com> - 2016-01-08 15:00 +0100
                Re: [PATCH 2/2] crypto: algif_hash - Require setkey before accept(2) Milan Broz <gmazyland@gmail.com> - 2016-01-09 11:20 +0100

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