linux-kernel - Re: linux-next: Tree for Aug 22 (evm)

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Date:	Mon, 22 Aug 2011 22:32:39 -0400
From:	Arnaud Lacombe <lacombar@...il.com>
To:	Mimi Zohar <zohar@...ux.vnet.ibm.com>
Cc:	Randy Dunlap <rdunlap@...otime.net>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	Mimi Zohar <zohar@...ibm.com>, linux-next@...r.kernel.org,
	LKML <linux-kernel@...r.kernel.org>, linux-kbuild@...r.kernel.org
Subject: Re: linux-next: Tree for Aug 22 (evm)

Hi,

On Mon, Aug 22, 2011 at 10:09 PM, Mimi Zohar <zohar@...ux.vnet.ibm.com> wrote:
> On Mon, 2011-08-22 at 17:49 -0700, Randy Dunlap wrote:
>> On Mon, 22 Aug 2011 20:47:00 -0400 Arnaud Lacombe wrote:
>>
>> > Hi,
>> >
>> > On Mon, Aug 22, 2011 at 3:53 PM, Randy Dunlap <rdunlap@...otime.net> wrote:
>> > > On Mon, 22 Aug 2011 14:53:04 +1000 Stephen Rothwell wrote:
>> > >
>> > >> Hi all,
>> > >>
>> > >> [The kernel.org mirroring is a bit low today]
>> > >
>> > > (on x86_64:)
>> > >
>> > > When CONFIG_EVM=y, CONFIG_CRYPTO_HASH2=m, CONFIG_TRUSTED_KEYS=m,
>> > > CONFIG_ENCRYPTED_KEYS=m, the build fails with:
>> > >
>> > You did not provide the value of CONFIG_TCG_TPM, I'll assume it was
>> > 'm'. That said, correct me if I'm wrong, but we currently have:
>>
>> Yes, it was 'm'.
>>
>> > menuconfig TCG_TPM
>> >         tristate "TPM Hardware Support"
>> >
>> > [...]
>> >
>> > config EVM
>> >         boolean "EVM support"
>> >         depends on SECURITY && KEYS && TCG_TPM
>> >
>> > which seems terribly broken to me... How can you have a built-in
>> > feature, which depends on another potentially-not-built-in feature ?
>>
>> Yup.
>
> Easy, different use cases. The TPM has been around and used for a while,
> not requiring it to be built-in.  EVM, a new use case, requires it to be
> built-in.
>
sorry, I think I misunderstood that last sentence. I assumed the 'it'
was referring to EVM, while taken in context with the previous
sentence, it might as well refers to TPM, in which case you want EVM
to 'depends on TCG_TPM = y'.

 - Arnaud

>> > If you change EVM to 'tristate', you will see that you are not allowed
>> > to make it built-in if TCG_TPM is not built-in.
>>
>> Right.
>
> The TPM, crypto, trusted and encrypted keys are tristate.  Like the
> LSMs, EVM is boolean, which when selected using 'make xconfig', converts
> the tristates to built-in.  The tristate/boolean mismatches aren't
> corrected, when .config is edited directly.
>
> Mimi
>
>> >  - Arnaud
>> >
>> > > (.text+0x378aa): undefined reference to `key_type_encrypted'
>> > > evm_crypto.c:(.text+0x37992): undefined reference to `crypto_alloc_shash'
>> > > evm_crypto.c:(.text+0x37a24): undefined reference to `crypto_shash_setkey'
>> > > evm_crypto.c:(.text+0x37ad9): undefined reference to `crypto_shash_update'
>> > > evm_crypto.c:(.text+0x37aeb): undefined reference to `crypto_shash_final'
>> > > (.text+0x37b4b): undefined reference to `crypto_shash_update'
>> > > (.text+0x37c61): undefined reference to `crypto_shash_update'
>> > > (.text+0x37cb9): undefined reference to `crypto_shash_update'
>> > >
>> > > even though EVM (Kconfig) selects ENCRYPTED_KEYS and TRUSTED_KEYS..
>> > > and even after I add "select CRYPTO_HASH2".
>> > >
>> > > Is this because EVM is bool and kconfig is confused about 'select's
>> > > when a bool is selecting tristates?  Shouldn't the tristates become
>> > > 'y' instead of 'm' if they are selected by a bool that is 'y'?
>> > >
>> > >
>> > > xconfig shows these symbol values:
>> > >
>> > > Symbol: EVM [=y]
>> > > Type : boolean
>> > > Prompt: EVM support
>> > > Defined at security/integrity/evm/Kconfig:1
>> > > Depends on: SECURITY [=y] && KEYS [=y] && TCG_TPM [=m]
>> > > Location:
>> > > -> Security options
>> > > Selects: CRYPTO_HMAC [=m] && CRYPTO_MD5 [=m] && CRYPTO_SHA1 [=m] && CRYPTO_HASH2 [=m] && ENCRYPTED_KEYS [=m] && TRUSTED_KEYS [=m]
>> > >
>> > >
>> > > Hm, changing TCG_TPM to =y also changes TRUSTED_KEYS and ENCRYPTED_KEYS and
>> > > lots of CRYPTO_ symbols from =m to =y.  There must be some kind of min/max
>> > > symbol checking that is confused?
>> > >
>> > there is definitively an underlying min/max, but I would not point
>> > finger too fast.
>>
>>
>> Thanks for your help.
>>
>> ---
>> ~Randy
>> *** Remember to use Documentation/SubmitChecklist when testing your code ***
>
>
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