[PATCH v3] KEYS: trusted: Fix trusted key backends when building as module

[PATCH v3] KEYS: trusted: Fix trusted key backends when building as module

[Andreas Rammhold]

Before this commit the kernel could end up with no trusted key sources
even though both of the currently supported backends (TPM and TEE) were
compiled as modules. This manifested in the trusted key type not being
registered at all.

When checking if a CONFIG_… preprocessor variable is defined we only
test for the builtin (=y) case and not the module (=m) case. By using
the IS_REACHABLE() macro we do test for both cases.

Fixes: 5d0682be3189 ("KEYS: trusted: Add generic trusted keys framework")
Signed-off-by: Andreas Rammhold <andreas@rammhold.de>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>

---

v3:
* Fixed patch formatting

v2:
* Fixed commit message
* Switched from IS_DEFINED() to IS_REACHABLE()

 security/keys/trusted-keys/trusted_core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/security/keys/trusted-keys/trusted_core.c b/security/keys/trusted-keys/trusted_core.c
index d5c891d8d353..5b35f1b87644 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 IS_REACHABLE(CONFIG_TCG_TPM)
 	{ "tpm", &trusted_key_tpm_ops },
 #endif
-#if defined(CONFIG_TEE)
+#if IS_REACHABLE(CONFIG_TEE)
 	{ "tee", &trusted_key_tee_ops },
 #endif
 };
-- 
2.32.0

Re: [PATCH v3] KEYS: trusted: Fix trusted key backends when building as module

[Sumit Garg]

On Fri, 30 Jul 2021 at 06:58, Andreas Rammhold <andreas@rammhold.de> wrote:
>
> Before this commit the kernel could end up with no trusted key sources
> even though both of the currently supported backends (TPM and TEE) were
> compiled as modules. This manifested in the trusted key type not being
> registered at all.
>
> When checking if a CONFIG_… preprocessor variable is defined we only
> test for the builtin (=y) case and not the module (=m) case. By using
> the IS_REACHABLE() macro we do test for both cases.
>
> Fixes: 5d0682be3189 ("KEYS: trusted: Add generic trusted keys framework")
> Signed-off-by: Andreas Rammhold <andreas@rammhold.de>
> Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
>
> ---
>
> v3:
> * Fixed patch formatting
>
> v2:
> * Fixed commit message
> * Switched from IS_DEFINED() to IS_REACHABLE()
>
>  security/keys/trusted-keys/trusted_core.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>

LGTM.

Reviewed-by: Sumit Garg <sumit.garg@linaro.org>

-Sumit

> diff --git a/security/keys/trusted-keys/trusted_core.c b/security/keys/trusted-keys/trusted_core.c
> index d5c891d8d353..5b35f1b87644 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 IS_REACHABLE(CONFIG_TCG_TPM)
>         { "tpm", &trusted_key_tpm_ops },
>  #endif
> -#if defined(CONFIG_TEE)
> +#if IS_REACHABLE(CONFIG_TEE)
>         { "tee", &trusted_key_tee_ops },
>  #endif
>  };
> --
> 2.32.0
>

Re: [PATCH v3] KEYS: trusted: Fix trusted key backends when building as module

[Ahmad Fatoum]

On 30.07.21 03:28, Andreas Rammhold wrote:
> Before this commit the kernel could end up with no trusted key sources
> even though both of the currently supported backends (TPM and TEE) were
> compiled as modules. This manifested in the trusted key type not being
> registered at all.
> 
> When checking if a CONFIG_… preprocessor variable is defined we only
> test for the builtin (=y) case and not the module (=m) case. By using
> the IS_REACHABLE() macro we do test for both cases.
> 
> Fixes: 5d0682be3189 ("KEYS: trusted: Add generic trusted keys framework")
> Signed-off-by: Andreas Rammhold <andreas@rammhold.de>
> Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>

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

> 
> ---
> 
> v3:
> * Fixed patch formatting
> 
> v2:
> * Fixed commit message
> * Switched from IS_DEFINED() to IS_REACHABLE()
> 
>  security/keys/trusted-keys/trusted_core.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/security/keys/trusted-keys/trusted_core.c b/security/keys/trusted-keys/trusted_core.c
> index d5c891d8d353..5b35f1b87644 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 IS_REACHABLE(CONFIG_TCG_TPM)
>  	{ "tpm", &trusted_key_tpm_ops },
>  #endif
> -#if defined(CONFIG_TEE)
> +#if IS_REACHABLE(CONFIG_TEE)
>  	{ "tee", &trusted_key_tee_ops },
>  #endif
>  };
> 


-- 
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Re: [PATCH v3] KEYS: trusted: Fix trusted key backends when building as module

[Ahmad Fatoum]

Dear trusted key maintainers,

On 30.07.21 03:28, Andreas Rammhold wrote:
> Before this commit the kernel could end up with no trusted key sources
> even though both of the currently supported backends (TPM and TEE) were
> compiled as modules. This manifested in the trusted key type not being
> registered at all.
> 
> When checking if a CONFIG_… preprocessor variable is defined we only
> test for the builtin (=y) case and not the module (=m) case. By using
> the IS_REACHABLE() macro we do test for both cases.
> 
> Fixes: 5d0682be3189 ("KEYS: trusted: Add generic trusted keys framework")
> Signed-off-by: Andreas Rammhold <andreas@rammhold.de>
> Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Does anyone intend to pick this up?

Cheers,
Ahmad



> 
> ---
> 
> v3:
> * Fixed patch formatting
> 
> v2:
> * Fixed commit message
> * Switched from IS_DEFINED() to IS_REACHABLE()
> 
>  security/keys/trusted-keys/trusted_core.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/security/keys/trusted-keys/trusted_core.c b/security/keys/trusted-keys/trusted_core.c
> index d5c891d8d353..5b35f1b87644 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 IS_REACHABLE(CONFIG_TCG_TPM)
>  	{ "tpm", &trusted_key_tpm_ops },
>  #endif
> -#if defined(CONFIG_TEE)
> +#if IS_REACHABLE(CONFIG_TEE)
>  	{ "tee", &trusted_key_tee_ops },
>  #endif
>  };
> 


-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

Re: [PATCH v3] KEYS: trusted: Fix trusted key backends when building as module

[Andreas Rammhold]

On 09:47 13.09.21, Ahmad Fatoum wrote:
> Dear trusted key maintainers,
> 
> On 30.07.21 03:28, Andreas Rammhold wrote:
> > Before this commit the kernel could end up with no trusted key sources
> > even though both of the currently supported backends (TPM and TEE) were
> > compiled as modules. This manifested in the trusted key type not being
> > registered at all.
> > 
> > When checking if a CONFIG_… preprocessor variable is defined we only
> > test for the builtin (=y) case and not the module (=m) case. By using
> > the IS_REACHABLE() macro we do test for both cases.
> > 
> > Fixes: 5d0682be3189 ("KEYS: trusted: Add generic trusted keys framework")
> > Signed-off-by: Andreas Rammhold <andreas@rammhold.de>
> > Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
> Does anyone intend to pick this up?

Did this end up in any tree by now? I am wondering if I should resend
the patch instead. Perhaps it was just overlooked?


Andi

Re: [PATCH v3] KEYS: trusted: Fix trusted key backends when building as module

[Mimi Zohar]

On Mon, 2021-09-27 at 10:51 +0200, Andreas Rammhold wrote:
> On 09:47 13.09.21, Ahmad Fatoum wrote:
> > Dear trusted key maintainers,
> > 
> > On 30.07.21 03:28, Andreas Rammhold wrote:
> > > Before this commit the kernel could end up with no trusted key sources
> > > even though both of the currently supported backends (TPM and TEE) were
> > > compiled as modules. This manifested in the trusted key type not being
> > > registered at all.
> > > 
> > > When checking if a CONFIG_… preprocessor variable is defined we only
> > > test for the builtin (=y) case and not the module (=m) case. By using
> > > the IS_REACHABLE() macro we do test for both cases.
> > > 
> > > Fixes: 5d0682be3189 ("KEYS: trusted: Add generic trusted keys framework")
> > > Signed-off-by: Andreas Rammhold <andreas@rammhold.de>
> > > Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
> > Does anyone intend to pick this up?
> 
> Did this end up in any tree by now? I am wondering if I should resend
> the patch instead. Perhaps it was just overlooked?

For EVM environments only using trusted and encrypted keys, not file
signatures, the trusted key is needed to decrypt the "master" key in
order to verify kernel modules.

Mimi

Re: [PATCH v3] KEYS: trusted: Fix trusted key backends when building as module

[Andreas Rammhold]

On 07:27 27.09.21, Mimi Zohar wrote:
> On Mon, 2021-09-27 at 10:51 +0200, Andreas Rammhold wrote:
> > On 09:47 13.09.21, Ahmad Fatoum wrote:
> > > Dear trusted key maintainers,
> > > 
> > > On 30.07.21 03:28, Andreas Rammhold wrote:
> > > > Before this commit the kernel could end up with no trusted key sources
> > > > even though both of the currently supported backends (TPM and TEE) were
> > > > compiled as modules. This manifested in the trusted key type not being
> > > > registered at all.
> > > > 
> > > > When checking if a CONFIG_… preprocessor variable is defined we only
> > > > test for the builtin (=y) case and not the module (=m) case. By using
> > > > the IS_REACHABLE() macro we do test for both cases.
> > > > 
> > > > Fixes: 5d0682be3189 ("KEYS: trusted: Add generic trusted keys framework")
> > > > Signed-off-by: Andreas Rammhold <andreas@rammhold.de>
> > > > Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
> > > Does anyone intend to pick this up?
> > 
> > Did this end up in any tree by now? I am wondering if I should resend
> > the patch instead. Perhaps it was just overlooked?
> 
> For EVM environments only using trusted and encrypted keys, not file
> signatures, the trusted key is needed to decrypt the "master" key in
> order to verify kernel modules.

So what you are saying is that right now (before this patch & after this
patch) you could compile a kernel that wouldn't be able to load any
modules when the trusted keychain part is built as module?


Andi

Re: [PATCH v3] KEYS: trusted: Fix trusted key backends when building as module

[Mimi Zohar]

On Mon, 2021-09-27 at 22:08 +0200, Andreas Rammhold wrote:
> On 07:27 27.09.21, Mimi Zohar wrote:
> > On Mon, 2021-09-27 at 10:51 +0200, Andreas Rammhold wrote:
> > > On 09:47 13.09.21, Ahmad Fatoum wrote:
> > > > Dear trusted key maintainers,
> > > > 
> > > > On 30.07.21 03:28, Andreas Rammhold wrote:
> > > > > Before this commit the kernel could end up with no trusted key sources
> > > > > even though both of the currently supported backends (TPM and TEE) were
> > > > > compiled as modules. This manifested in the trusted key type not being
> > > > > registered at all.
> > > > > 
> > > > > When checking if a CONFIG_… preprocessor variable is defined we only
> > > > > test for the builtin (=y) case and not the module (=m) case. By using
> > > > > the IS_REACHABLE() macro we do test for both cases.
> > > > > 
> > > > > Fixes: 5d0682be3189 ("KEYS: trusted: Add generic trusted keys framework")
> > > > > Signed-off-by: Andreas Rammhold <andreas@rammhold.de>
> > > > > Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
> > > > Does anyone intend to pick this up?
> > > 
> > > Did this end up in any tree by now? I am wondering if I should resend
> > > the patch instead. Perhaps it was just overlooked?
> > 
> > For EVM environments only using trusted and encrypted keys, not file
> > signatures, the trusted key is needed to decrypt the "master" key in
> > order to verify kernel modules.
> 
> So what you are saying is that right now (before this patch & after this
> patch) you could compile a kernel that wouldn't be able to load any
> modules when the trusted keychain part is built as module?

Before this patch, trusted and encrypted keys are builtin, so verifying
kernel modules with security.evm containing an EVM hmac would succeed. 
Afterwards it would fail, as there's a dependency on the trusted key to
verify the integrity of the trusted key module.

Mimi

Re: [PATCH v3] KEYS: trusted: Fix trusted key backends when building as module

[Andreas Rammhold]

On 16:33 27.09.21, Mimi Zohar wrote:
> On Mon, 2021-09-27 at 22:08 +0200, Andreas Rammhold wrote:
> > On 07:27 27.09.21, Mimi Zohar wrote:
> > > On Mon, 2021-09-27 at 10:51 +0200, Andreas Rammhold wrote:
> > > > On 09:47 13.09.21, Ahmad Fatoum wrote:
> > > > > Dear trusted key maintainers,
> > > > > 
> > > > > On 30.07.21 03:28, Andreas Rammhold wrote:
> > > > > > Before this commit the kernel could end up with no trusted key sources
> > > > > > even though both of the currently supported backends (TPM and TEE) were
> > > > > > compiled as modules. This manifested in the trusted key type not being
> > > > > > registered at all.
> > > > > > 
> > > > > > When checking if a CONFIG_… preprocessor variable is defined we only
> > > > > > test for the builtin (=y) case and not the module (=m) case. By using
> > > > > > the IS_REACHABLE() macro we do test for both cases.
> > > > > > 
> > > > > > Fixes: 5d0682be3189 ("KEYS: trusted: Add generic trusted keys framework")
> > > > > > Signed-off-by: Andreas Rammhold <andreas@rammhold.de>
> > > > > > Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
> > > > > Does anyone intend to pick this up?
> > > > 
> > > > Did this end up in any tree by now? I am wondering if I should resend
> > > > the patch instead. Perhaps it was just overlooked?
> > > 
> > > For EVM environments only using trusted and encrypted keys, not file
> > > signatures, the trusted key is needed to decrypt the "master" key in
> > > order to verify kernel modules.
> > 
> > So what you are saying is that right now (before this patch & after this
> > patch) you could compile a kernel that wouldn't be able to load any
> > modules when the trusted keychain part is built as module?
> 
> Before this patch, trusted and encrypted keys are builtin, so verifying
> kernel modules with security.evm containing an EVM hmac would succeed. 
> Afterwards it would fail, as there's a dependency on the trusted key to
> verify the integrity of the trusted key module.

But building with =m was a valid configuration which is the original
reason for me submitting the patch. So perhaps this should not be
allowed to be a module then?

Re: [PATCH v3] KEYS: trusted: Fix trusted key backends when building as module

[Mimi Zohar]

On Mon, 2021-09-27 at 22:55 +0200, Andreas Rammhold wrote:
> On 16:33 27.09.21, Mimi Zohar wrote:
> > On Mon, 2021-09-27 at 22:08 +0200, Andreas Rammhold wrote:
> > > On 07:27 27.09.21, Mimi Zohar wrote:
> > > > On Mon, 2021-09-27 at 10:51 +0200, Andreas Rammhold wrote:
> > > > > On 09:47 13.09.21, Ahmad Fatoum wrote:
> > > > > > Dear trusted key maintainers,
> > > > > > 
> > > > > > On 30.07.21 03:28, Andreas Rammhold wrote:
> > > > > > > Before this commit the kernel could end up with no trusted key sources
> > > > > > > even though both of the currently supported backends (TPM and TEE) were
> > > > > > > compiled as modules. This manifested in the trusted key type not being
> > > > > > > registered at all.
> > > > > > > 
> > > > > > > When checking if a CONFIG_… preprocessor variable is defined we only
> > > > > > > test for the builtin (=y) case and not the module (=m) case. By using
> > > > > > > the IS_REACHABLE() macro we do test for both cases.
> > > > > > > 
> > > > > > > Fixes: 5d0682be3189 ("KEYS: trusted: Add generic trusted keys framework")
> > > > > > > Signed-off-by: Andreas Rammhold <andreas@rammhold.de>
> > > > > > > Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
> > > > > > Does anyone intend to pick this up?
> > > > > 
> > > > > Did this end up in any tree by now? I am wondering if I should resend
> > > > > the patch instead. Perhaps it was just overlooked?
> > > > 
> > > > For EVM environments only using trusted and encrypted keys, not file
> > > > signatures, the trusted key is needed to decrypt the "master" key in
> > > > order to verify kernel modules.
> > > 
> > > So what you are saying is that right now (before this patch & after this
> > > patch) you could compile a kernel that wouldn't be able to load any
> > > modules when the trusted keychain part is built as module?
> > 
> > Before this patch, trusted and encrypted keys are builtin, so verifying
> > kernel modules with security.evm containing an EVM hmac would succeed. 
> > Afterwards it would fail, as there's a dependency on the trusted key to
> > verify the integrity of the trusted key module.
> 
> But building with =m was a valid configuration which is the original
> reason for me submitting the patch. So perhaps this should not be
> allowed to be a module then?

My mistake.  Trusted and encrypted key types have always been defined
as tristate.  Only when EVM selects encrypted keys, and by extension
trusted keys, are they builtin.

Mimi

Re: [PATCH v3] KEYS: trusted: Fix trusted key backends when building as module

[Andreas Rammhold]

On 17:31 27.09.21, Mimi Zohar wrote:
> On Mon, 2021-09-27 at 22:55 +0200, Andreas Rammhold wrote:
> > On 16:33 27.09.21, Mimi Zohar wrote:
> > > On Mon, 2021-09-27 at 22:08 +0200, Andreas Rammhold wrote:
> > > > On 07:27 27.09.21, Mimi Zohar wrote:
> > > > > On Mon, 2021-09-27 at 10:51 +0200, Andreas Rammhold wrote:
> > > > > > On 09:47 13.09.21, Ahmad Fatoum wrote:
> > > > > > > Dear trusted key maintainers,
> > > > > > > 
> > > > > > > On 30.07.21 03:28, Andreas Rammhold wrote:
> > > > > > > > Before this commit the kernel could end up with no trusted key sources
> > > > > > > > even though both of the currently supported backends (TPM and TEE) were
> > > > > > > > compiled as modules. This manifested in the trusted key type not being
> > > > > > > > registered at all.
> > > > > > > > 
> > > > > > > > When checking if a CONFIG_… preprocessor variable is defined we only
> > > > > > > > test for the builtin (=y) case and not the module (=m) case. By using
> > > > > > > > the IS_REACHABLE() macro we do test for both cases.
> > > > > > > > 
> > > > > > > > Fixes: 5d0682be3189 ("KEYS: trusted: Add generic trusted keys framework")
> > > > > > > > Signed-off-by: Andreas Rammhold <andreas@rammhold.de>
> > > > > > > > Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
> > > > > > > Does anyone intend to pick this up?
> > > > > > 
> > > > > > Did this end up in any tree by now? I am wondering if I should resend
> > > > > > the patch instead. Perhaps it was just overlooked?
> > > > > 
> > > > > For EVM environments only using trusted and encrypted keys, not file
> > > > > signatures, the trusted key is needed to decrypt the "master" key in
> > > > > order to verify kernel modules.
> > > > 
> > > > So what you are saying is that right now (before this patch & after this
> > > > patch) you could compile a kernel that wouldn't be able to load any
> > > > modules when the trusted keychain part is built as module?
> > > 
> > > Before this patch, trusted and encrypted keys are builtin, so verifying
> > > kernel modules with security.evm containing an EVM hmac would succeed. 
> > > Afterwards it would fail, as there's a dependency on the trusted key to
> > > verify the integrity of the trusted key module.
> > 
> > But building with =m was a valid configuration which is the original
> > reason for me submitting the patch. So perhaps this should not be
> > allowed to be a module then?
> 
> My mistake.  Trusted and encrypted key types have always been defined
> as tristate.  Only when EVM selects encrypted keys, and by extension
> trusted keys, are they builtin.

So how do we go about this patch? Building the TPM support as module has
broken actually using the trusted backend. This patch fixes that while
still allowing it to be a builtin. If there is some configuration there
a module isn't acceptable I am sure that is handled within Kconfig?


Andi

Re: [PATCH v3] KEYS: trusted: Fix trusted key backends when building as module

[Ahmad Fatoum]

Hello Mimi, David, Jarkko and James,

On 02.10.21 23:47, Andreas Rammhold wrote:
>> My mistake.  Trusted and encrypted key types have always been defined
>> as tristate.  Only when EVM selects encrypted keys, and by extension
>> trusted keys, are they builtin.
> 
> So how do we go about this patch? Building the TPM support as module has
> broken actually using the trusted backend. This patch fixes that while
> still allowing it to be a builtin. If there is some configuration there
> a module isn't acceptable I am sure that is handled within Kconfig?
Can anyone of you four pick this up? Andreas' regression fix has
had Jarkko's Reviewed-by for close to two months and a half now.

Thanks,
Ahmad

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |