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[v2,4/6] KEYS: trusted: allow trust sources to use kernel RNG for key material

Message ID 77c472a8b373f4a9de646c91214db546bbbe1e81.1624364386.git-series.a.fatoum@pengutronix.de (mailing list archive)
State New, archived
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
The two existing trusted key sources don't make use of the kernel RNG,
but instead let the hardware that does the sealing/unsealing also
generate the random key material. While a previous change offers users
the choice to use the kernel RNG instead for both, new trust sources
may want to unconditionally use the kernel RNG for generating key
material, like it's done elsewhere in the kernel.

This is especially prudent for hardware that has proven-in-production
HWRNG drivers implemented, as otherwise code would have to be duplicated
only to arrive at a possibly worse result.

Make this possible by turning struct trusted_key_ops::get_random
into an optional member. If a driver leaves it NULL, kernel RNG
will be used instead.

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: "Serge E. Hallyn" <serge@hallyn.com>
Cc: "Horia Geantă" <horia.geanta@nxp.com>
Cc: Aymen Sghaier <aymen.sghaier@nxp.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Udit Agarwal <udit.agarwal@nxp.com>
Cc: Eric Biggers <ebiggers@kernel.org>
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
 include/keys/trusted-type.h               | 2 +-
 security/keys/trusted-keys/trusted_core.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)
diff mbox series


diff --git a/include/keys/trusted-type.h b/include/keys/trusted-type.h
index d89fa2579ac0..4eb64548a74f 100644
--- a/include/keys/trusted-type.h
+++ b/include/keys/trusted-type.h
@@ -64,7 +64,7 @@  struct trusted_key_ops {
 	/* Unseal a key. */
 	int (*unseal)(struct trusted_key_payload *p, char *datablob);
-	/* Get a randomized key. */
+	/* Optional: Get a randomized key. */
 	int (*get_random)(unsigned char *key, size_t key_len);
 	/* Exit key interface. */
diff --git a/security/keys/trusted-keys/trusted_core.c b/security/keys/trusted-keys/trusted_core.c
index 2eeb7117e86b..8d829e6866ca 100644
--- a/security/keys/trusted-keys/trusted_core.c
+++ b/security/keys/trusted-keys/trusted_core.c
@@ -351,7 +351,7 @@  static int __init init_trusted(void)
 		get_random = trusted_key_sources[i].ops->get_random;
-		if (trusted_kernel_rng)
+		if (trusted_kernel_rng || !get_random)
 			get_random = kernel_get_random;