diff mbox series

[v2,1/6] KEYS: trusted: allow use of TEE as backend without TCG_TPM support

Message ID f8285eb0135ba30c9d846cf9dd395d1f5f8b1efc.1624364386.git-series.a.fatoum@pengutronix.de
State Superseded
Headers show
Series KEYS: trusted: Introduce support for NXP CAAM-based trusted keys | expand

Commit Message

Ahmad Fatoum June 22, 2021, 12:37 p.m. UTC
With recent rework, trusted keys are no longer limited to TPM as trust
source. The Kconfig symbol is unchanged however leading to a few issues:

 - TCG_TPM is required, even if only TEE is to be used
 - Enabling TCG_TPM, but excluding it from available trusted sources
   is not possible
 - TEE=m && TRUSTED_KEYS=y will lead to TEE support being silently
   dropped, which is not the best user experience

Remedy these issues by introducing two new Kconfig symbols:
TRUSTED_KEYS_TPM and TRUSTED_KEYS_TEE with the appropriate
dependencies.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
To: James Bottomley <jejb@linux.ibm.com>
To: Jarkko Sakkinen <jarkko@kernel.org>
To: Mimi Zohar <zohar@linux.ibm.com>
To: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: "Horia Geantă" <horia.geanta@nxp.com>
Cc: Aymen Sghaier <aymen.sghaier@nxp.com>
Cc: Udit Agarwal <udit.agarwal@nxp.com>
Cc: Jan Luebbe <j.luebbe@pengutronix.de>
Cc: David Gstir <david@sigma-star.at>
Cc: Richard Weinberger <richard@nod.at>
Cc: Franck LENORMAND <franck.lenormand@nxp.com>
Cc: Sumit Garg <sumit.garg@linaro.org>
Cc: keyrings@vger.kernel.org
Cc: linux-crypto@vger.kernel.org
Cc: linux-integrity@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
---
 security/keys/Kconfig                     | 14 ++++++-------
 security/keys/trusted-keys/Kconfig        | 25 ++++++++++++++++++++++++-
 security/keys/trusted-keys/Makefile       |  8 +++++---
 security/keys/trusted-keys/trusted_core.c |  4 ++--
 4 files changed, 39 insertions(+), 12 deletions(-)
 create mode 100644 security/keys/trusted-keys/Kconfig

Comments

Sumit Garg July 19, 2021, 8:04 a.m. UTC | #1
Hi Ahmad,

On Tue, 22 Jun 2021 at 18:08, Ahmad Fatoum <a.fatoum@pengutronix.de> wrote:
>

> With recent rework, trusted keys are no longer limited to TPM as trust

> source. The Kconfig symbol is unchanged however leading to a few issues:

>

>  - TCG_TPM is required, even if only TEE is to be used

>  - Enabling TCG_TPM, but excluding it from available trusted sources

>    is not possible

>  - TEE=m && TRUSTED_KEYS=y will lead to TEE support being silently

>    dropped, which is not the best user experience

>

> Remedy these issues by introducing two new Kconfig symbols:

> TRUSTED_KEYS_TPM and TRUSTED_KEYS_TEE with the appropriate

> dependencies.

>


This should include a fixes tag to the rework commit.

> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>

> ---

> To: James Bottomley <jejb@linux.ibm.com>

> To: Jarkko Sakkinen <jarkko@kernel.org>

> To: Mimi Zohar <zohar@linux.ibm.com>

> To: David Howells <dhowells@redhat.com>

> Cc: James Morris <jmorris@namei.org>

> Cc: Eric Biggers <ebiggers@kernel.org>

> Cc: "Serge E. Hallyn" <serge@hallyn.com>

> Cc: "Horia Geantă" <horia.geanta@nxp.com>

> Cc: Aymen Sghaier <aymen.sghaier@nxp.com>

> Cc: Udit Agarwal <udit.agarwal@nxp.com>

> Cc: Jan Luebbe <j.luebbe@pengutronix.de>

> Cc: David Gstir <david@sigma-star.at>

> Cc: Richard Weinberger <richard@nod.at>

> Cc: Franck LENORMAND <franck.lenormand@nxp.com>

> Cc: Sumit Garg <sumit.garg@linaro.org>

> Cc: keyrings@vger.kernel.org

> Cc: linux-crypto@vger.kernel.org

> Cc: linux-integrity@vger.kernel.org

> Cc: linux-kernel@vger.kernel.org

> Cc: linux-security-module@vger.kernel.org

> ---

>  security/keys/Kconfig                     | 14 ++++++-------

>  security/keys/trusted-keys/Kconfig        | 25 ++++++++++++++++++++++++-

>  security/keys/trusted-keys/Makefile       |  8 +++++---

>  security/keys/trusted-keys/trusted_core.c |  4 ++--

>  4 files changed, 39 insertions(+), 12 deletions(-)

>  create mode 100644 security/keys/trusted-keys/Kconfig

>

> diff --git a/security/keys/Kconfig b/security/keys/Kconfig

> index 64b81abd087e..6fdb953b319f 100644

> --- a/security/keys/Kconfig

> +++ b/security/keys/Kconfig

> @@ -70,23 +70,23 @@ config BIG_KEYS

>

>  config TRUSTED_KEYS

>         tristate "TRUSTED KEYS"

> -       depends on KEYS && TCG_TPM

> +       depends on KEYS


>         select CRYPTO

>         select CRYPTO_HMAC

>         select CRYPTO_SHA1

>         select CRYPTO_HASH_INFO


Should move these as well to TRUSTED_KEYS_TPM as the core code doesn't
mandate their need.

> -       select ASN1_ENCODER

> -       select OID_REGISTRY

> -       select ASN1

>         help

>           This option provides support for creating, sealing, and unsealing

>           keys in the kernel. Trusted keys are random number symmetric keys,

> -         generated and RSA-sealed by the TPM. The TPM only unseals the keys,

> -         if the boot PCRs and other criteria match.  Userspace will only ever

> -         see encrypted blobs.

> +         generated and sealed by a trust source selected at kernel boot-time.

> +         Userspace will only ever see encrypted blobs.

>

>           If you are unsure as to whether this is required, answer N.

>

> +if TRUSTED_KEYS

> +source "security/keys/trusted-keys/Kconfig"

> +endif

> +

>  config ENCRYPTED_KEYS

>         tristate "ENCRYPTED KEYS"

>         depends on KEYS

> diff --git a/security/keys/trusted-keys/Kconfig b/security/keys/trusted-keys/Kconfig

> new file mode 100644

> index 000000000000..24af4aaceebf

> --- /dev/null

> +++ b/security/keys/trusted-keys/Kconfig

> @@ -0,0 +1,25 @@

> +config TRUSTED_KEYS_TPM

> +       bool "TPM-based trusted keys"

> +       depends on TCG_TPM >= TRUSTED_KEYS

> +       default y

> +       select ASN1_ENCODER

> +       select OID_REGISTRY

> +       select ASN1

> +       help

> +         Enable use of the Trusted Platform Module (TPM) as trusted key

> +         backend. Trusted keys are are random number symmetric keys,

> +         which will be generated and RSA-sealed by the TPM.

> +         The TPM only unseals the keys, if the boot PCRs and other

> +         criteria match.

> +

> +config TRUSTED_KEYS_TEE

> +       bool "TEE-based trusted keys"

> +       depends on TEE >= TRUSTED_KEYS

> +       default y

> +       help

> +         Enable use of the Trusted Execution Environment (TEE) as trusted

> +         key backend.

> +

> +if !TRUSTED_KEYS_TPM && !TRUSTED_KEYS_TEE

> +comment "No trust source selected!"

> +endif

> diff --git a/security/keys/trusted-keys/Makefile b/security/keys/trusted-keys/Makefile

> index feb8b6c3cc79..96fc6c377398 100644

> --- a/security/keys/trusted-keys/Makefile

> +++ b/security/keys/trusted-keys/Makefile

> @@ -5,10 +5,12 @@

>

>  obj-$(CONFIG_TRUSTED_KEYS) += trusted.o

>  trusted-y += trusted_core.o

> -trusted-y += trusted_tpm1.o

> +trusted-$(CONFIG_TRUSTED_KEYS_TPM) += trusted_tpm1.o

>

>  $(obj)/trusted_tpm2.o: $(obj)/tpm2key.asn1.h

> -trusted-y += trusted_tpm2.o

> -trusted-y += tpm2key.asn1.o

> +trusted-$(CONFIG_TRUSTED_KEYS_TPM) += trusted_tpm2.o

> +trusted-$(CONFIG_TRUSTED_KEYS_TPM) += tpm2key.asn1.o

> +

> +trusted-$(CONFIG_TRUSTED_KEYS_TEE) += trusted_tee.o

>

>  trusted-$(CONFIG_TEE) += trusted_tee.o


This should be dropped.

-Sumit

> diff --git a/security/keys/trusted-keys/trusted_core.c b/security/keys/trusted-keys/trusted_core.c

> index d5c891d8d353..8cab69e5d0da 100644

> --- a/security/keys/trusted-keys/trusted_core.c

> +++ b/security/keys/trusted-keys/trusted_core.c

> @@ -27,10 +27,10 @@ module_param_named(source, trusted_key_source, charp, 0);

>  MODULE_PARM_DESC(source, "Select trusted keys source (tpm or tee)");

>

>  static const struct trusted_key_source trusted_key_sources[] = {

> -#if defined(CONFIG_TCG_TPM)

> +#if defined(CONFIG_TRUSTED_KEYS_TPM)

>         { "tpm", &trusted_key_tpm_ops },

>  #endif

> -#if defined(CONFIG_TEE)

> +#if defined(CONFIG_TRUSTED_KEYS_TEE)

>         { "tee", &trusted_key_tee_ops },

>  #endif

>  };

> --

> git-series 0.9.1
Ahmad Fatoum July 19, 2021, 9:09 a.m. UTC | #2
Hello Sumit,

On 19.07.21 10:04, Sumit Garg wrote:
> Hi Ahmad,

> 

> On Tue, 22 Jun 2021 at 18:08, Ahmad Fatoum <a.fatoum@pengutronix.de> wrote:

>>

>> With recent rework, trusted keys are no longer limited to TPM as trust

>> source. The Kconfig symbol is unchanged however leading to a few issues:

>>

>>  - TCG_TPM is required, even if only TEE is to be used

>>  - Enabling TCG_TPM, but excluding it from available trusted sources

>>    is not possible

>>  - TEE=m && TRUSTED_KEYS=y will lead to TEE support being silently

>>    dropped, which is not the best user experience

>>

>> Remedy these issues by introducing two new Kconfig symbols:

>> TRUSTED_KEYS_TPM and TRUSTED_KEYS_TEE with the appropriate

>> dependencies.

>>

> 

> This should include a fixes tag to the rework commit.


Yes. I wasn't aware of the regression that Andreas (CC'd) recently
reported. Knowing, it now indeed warrants a backport. Will add in v2.

>> diff --git a/security/keys/Kconfig b/security/keys/Kconfig

>> index 64b81abd087e..6fdb953b319f 100644

>> --- a/security/keys/Kconfig

>> +++ b/security/keys/Kconfig

>> @@ -70,23 +70,23 @@ config BIG_KEYS

>>

>>  config TRUSTED_KEYS

>>         tristate "TRUSTED KEYS"

>> -       depends on KEYS && TCG_TPM

>> +       depends on KEYS

> 

>>         select CRYPTO

>>         select CRYPTO_HMAC

>>         select CRYPTO_SHA1

>>         select CRYPTO_HASH_INFO

> 

> Should move these as well to TRUSTED_KEYS_TPM as the core code doesn't

> mandate their need.


Ok, will test and change appropriately.

> 

>> -       select ASN1_ENCODER

>> -       select OID_REGISTRY

>> -       select ASN1


>>  $(obj)/trusted_tpm2.o: $(obj)/tpm2key.asn1.h

>> -trusted-y += trusted_tpm2.o

>> -trusted-y += tpm2key.asn1.o

>> +trusted-$(CONFIG_TRUSTED_KEYS_TPM) += trusted_tpm2.o

>> +trusted-$(CONFIG_TRUSTED_KEYS_TPM) += tpm2key.asn1.o

>> +

>> +trusted-$(CONFIG_TRUSTED_KEYS_TEE) += trusted_tee.o

>>

>>  trusted-$(CONFIG_TEE) += trusted_tee.o

> 

> This should be dropped.


Right..

Thanks for the review. I'll isolate this patch for v2.

Cheers,
Ahmad


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diff mbox series

Patch

diff --git a/security/keys/Kconfig b/security/keys/Kconfig
index 64b81abd087e..6fdb953b319f 100644
--- a/security/keys/Kconfig
+++ b/security/keys/Kconfig
@@ -70,23 +70,23 @@  config BIG_KEYS
 
 config TRUSTED_KEYS
 	tristate "TRUSTED KEYS"
-	depends on KEYS && TCG_TPM
+	depends on KEYS
 	select CRYPTO
 	select CRYPTO_HMAC
 	select CRYPTO_SHA1
 	select CRYPTO_HASH_INFO
-	select ASN1_ENCODER
-	select OID_REGISTRY
-	select ASN1
 	help
 	  This option provides support for creating, sealing, and unsealing
 	  keys in the kernel. Trusted keys are random number symmetric keys,
-	  generated and RSA-sealed by the TPM. The TPM only unseals the keys,
-	  if the boot PCRs and other criteria match.  Userspace will only ever
-	  see encrypted blobs.
+	  generated and sealed by a trust source selected at kernel boot-time.
+	  Userspace will only ever see encrypted blobs.
 
 	  If you are unsure as to whether this is required, answer N.
 
+if TRUSTED_KEYS
+source "security/keys/trusted-keys/Kconfig"
+endif
+
 config ENCRYPTED_KEYS
 	tristate "ENCRYPTED KEYS"
 	depends on KEYS
diff --git a/security/keys/trusted-keys/Kconfig b/security/keys/trusted-keys/Kconfig
new file mode 100644
index 000000000000..24af4aaceebf
--- /dev/null
+++ b/security/keys/trusted-keys/Kconfig
@@ -0,0 +1,25 @@ 
+config TRUSTED_KEYS_TPM
+	bool "TPM-based trusted keys"
+	depends on TCG_TPM >= TRUSTED_KEYS
+	default y
+ 	select ASN1_ENCODER
+	select OID_REGISTRY
+	select ASN1
+	help
+	  Enable use of the Trusted Platform Module (TPM) as trusted key
+	  backend. Trusted keys are are random number symmetric keys,
+	  which will be generated and RSA-sealed by the TPM.
+	  The TPM only unseals the keys, if the boot PCRs and other
+	  criteria match.
+
+config TRUSTED_KEYS_TEE
+	bool "TEE-based trusted keys"
+	depends on TEE >= TRUSTED_KEYS
+	default y
+	help
+	  Enable use of the Trusted Execution Environment (TEE) as trusted
+	  key backend.
+
+if !TRUSTED_KEYS_TPM && !TRUSTED_KEYS_TEE
+comment "No trust source selected!"
+endif
diff --git a/security/keys/trusted-keys/Makefile b/security/keys/trusted-keys/Makefile
index feb8b6c3cc79..96fc6c377398 100644
--- a/security/keys/trusted-keys/Makefile
+++ b/security/keys/trusted-keys/Makefile
@@ -5,10 +5,12 @@ 
 
 obj-$(CONFIG_TRUSTED_KEYS) += trusted.o
 trusted-y += trusted_core.o
-trusted-y += trusted_tpm1.o
+trusted-$(CONFIG_TRUSTED_KEYS_TPM) += trusted_tpm1.o
 
 $(obj)/trusted_tpm2.o: $(obj)/tpm2key.asn1.h
-trusted-y += trusted_tpm2.o
-trusted-y += tpm2key.asn1.o
+trusted-$(CONFIG_TRUSTED_KEYS_TPM) += trusted_tpm2.o
+trusted-$(CONFIG_TRUSTED_KEYS_TPM) += tpm2key.asn1.o
+
+trusted-$(CONFIG_TRUSTED_KEYS_TEE) += trusted_tee.o
 
 trusted-$(CONFIG_TEE) += trusted_tee.o
diff --git a/security/keys/trusted-keys/trusted_core.c b/security/keys/trusted-keys/trusted_core.c
index d5c891d8d353..8cab69e5d0da 100644
--- a/security/keys/trusted-keys/trusted_core.c
+++ b/security/keys/trusted-keys/trusted_core.c
@@ -27,10 +27,10 @@  module_param_named(source, trusted_key_source, charp, 0);
 MODULE_PARM_DESC(source, "Select trusted keys source (tpm or tee)");
 
 static const struct trusted_key_source trusted_key_sources[] = {
-#if defined(CONFIG_TCG_TPM)
+#if defined(CONFIG_TRUSTED_KEYS_TPM)
 	{ "tpm", &trusted_key_tpm_ops },
 #endif
-#if defined(CONFIG_TEE)
+#if defined(CONFIG_TRUSTED_KEYS_TEE)
 	{ "tee", &trusted_key_tee_ops },
 #endif
 };