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authorAhmad Fatoum <a.fatoum@pengutronix.de>2022-05-13 16:56:59 +0200
committerJarkko Sakkinen <jarkko@kernel.org>2022-05-23 18:47:50 +0300
commitbe07858fbf8115fc74528292c2ee8775fe49116f (patch)
treee0ca3b5afa5dc944c6115cd3f4a04f208c37e766 /security
parentaf402ee3c045b0cbd10b7e66d2431304ac9e69bb (diff)
downloadlinux-be07858fbf8115fc74528292c2ee8775fe49116f.tar.bz2
KEYS: trusted: allow use of TEE as backend without TCG_TPM support
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 boolean Kconfig symbols: TRUSTED_KEYS_TPM and TRUSTED_KEYS_TEE with the appropriate dependencies. Any new code depending on the TPM trusted key backend in particular or symbols exported by it will now need to explicitly state that it depends on TRUSTED_KEYS && TRUSTED_KEYS_TPM The latter to ensure the dependency is built and the former to ensure it's reachable for module builds. There are no such users yet. Reviewed-by: Sumit Garg <sumit.garg@linaro.org> Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org> Reviewed-by: Pankaj Gupta <pankaj.gupta@nxp.com> Tested-by: Pankaj Gupta <pankaj.gupta@nxp.com> Tested-by: Andreas Rammhold <andreas@rammhold.de> Tested-by: Tim Harvey <tharvey@gateworks.com> Tested-by: Michael Walle <michael@walle.cc> # on ls1028a (non-E and E) Tested-by: John Ernberg <john.ernberg@actia.se> # iMX8QXP Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de> Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Diffstat (limited to 'security')
-rw-r--r--security/keys/Kconfig18
-rw-r--r--security/keys/trusted-keys/Kconfig29
-rw-r--r--security/keys/trusted-keys/Makefile8
-rw-r--r--security/keys/trusted-keys/trusted_core.c4
4 files changed, 42 insertions, 17 deletions
diff --git a/security/keys/Kconfig b/security/keys/Kconfig
index 0e30b361e1c1..abb03a1b2a5c 100644
--- a/security/keys/Kconfig
+++ b/security/keys/Kconfig
@@ -70,23 +70,19 @@ config BIG_KEYS
config TRUSTED_KEYS
tristate "TRUSTED KEYS"
- depends on KEYS && TCG_TPM
- select CRYPTO
- select CRYPTO_HMAC
- select CRYPTO_SHA1
- select CRYPTO_HASH_INFO
- select ASN1_ENCODER
- select OID_REGISTRY
- select ASN1
+ depends on KEYS
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..fc4abd581abb
--- /dev/null
+++ b/security/keys/trusted-keys/Kconfig
@@ -0,0 +1,29 @@
+config TRUSTED_KEYS_TPM
+ bool "TPM-based trusted keys"
+ depends on TCG_TPM >= TRUSTED_KEYS
+ default y
+ select CRYPTO
+ select CRYPTO_HMAC
+ select CRYPTO_SHA1
+ select CRYPTO_HASH_INFO
+ select ASN1_ENCODER
+ select OID_REGISTRY
+ select ASN1
+ help
+ Enable use of the Trusted Platform Module (TPM) as trusted key
+ backend. Trusted keys 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..2e2371eae4d5 100644
--- a/security/keys/trusted-keys/Makefile
+++ b/security/keys/trusted-keys/Makefile
@@ -5,10 +5,10 @@
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_TEE) += trusted_tee.o
+trusted-$(CONFIG_TRUSTED_KEYS_TEE) += trusted_tee.o
diff --git a/security/keys/trusted-keys/trusted_core.c b/security/keys/trusted-keys/trusted_core.c
index 9b9d3ef79cbe..7cdbd16aed30 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 IS_REACHABLE(CONFIG_TCG_TPM)
+#if defined(CONFIG_TRUSTED_KEYS_TPM)
{ "tpm", &trusted_key_tpm_ops },
#endif
-#if IS_REACHABLE(CONFIG_TEE)
+#if defined(CONFIG_TRUSTED_KEYS_TEE)
{ "tee", &trusted_key_tee_ops },
#endif
};