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 <[email protected]>
---
To: James Bottomley <[email protected]>
To: Jarkko Sakkinen <[email protected]>
To: Mimi Zohar <[email protected]>
To: David Howells <[email protected]>
Cc: James Morris <[email protected]>
Cc: Eric Biggers <[email protected]>
Cc: "Serge E. Hallyn" <[email protected]>
Cc: "Horia Geantă" <[email protected]>
Cc: Aymen Sghaier <[email protected]>
Cc: Udit Agarwal <[email protected]>
Cc: Jan Luebbe <[email protected]>
Cc: David Gstir <[email protected]>
Cc: Richard Weinberger <[email protected]>
Cc: Franck LENORMAND <[email protected]>
Cc: Sumit Garg <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
---
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
- 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
};
--
git-series 0.9.1
Hi Ahmad,
On Tue, 22 Jun 2021 at 18:08, Ahmad Fatoum <[email protected]> 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 <[email protected]>
> ---
> To: James Bottomley <[email protected]>
> To: Jarkko Sakkinen <[email protected]>
> To: Mimi Zohar <[email protected]>
> To: David Howells <[email protected]>
> Cc: James Morris <[email protected]>
> Cc: Eric Biggers <[email protected]>
> Cc: "Serge E. Hallyn" <[email protected]>
> Cc: "Horia Geantă" <[email protected]>
> Cc: Aymen Sghaier <[email protected]>
> Cc: Udit Agarwal <[email protected]>
> Cc: Jan Luebbe <[email protected]>
> Cc: David Gstir <[email protected]>
> Cc: Richard Weinberger <[email protected]>
> Cc: Franck LENORMAND <[email protected]>
> Cc: Sumit Garg <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> ---
> 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
Hello Sumit,
On 19.07.21 10:04, Sumit Garg wrote:
> Hi Ahmad,
>
> On Tue, 22 Jun 2021 at 18:08, Ahmad Fatoum <[email protected]> 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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