From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A620DC41513 for ; Mon, 16 Oct 2023 08:43:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231795AbjJPInl (ORCPT ); Mon, 16 Oct 2023 04:43:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47912 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232568AbjJPInk (ORCPT ); Mon, 16 Oct 2023 04:43:40 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 85CC3F5 for ; Mon, 16 Oct 2023 01:43:37 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9B227C433C7; Mon, 16 Oct 2023 08:43:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1697445817; bh=v/Nh62iBmrd8zh2kgvASVMT8Y9s1ToqGjDnCLIxDd/Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RvH053z4cjAEdOXeEYEdvNSJuYjy+DSwvyMcMT5galm5IyrNafItoXQjybvbCQx5o EBNr3VJseQN5Ff1BQoTEUzjzzmfgX295ywnq5LatqkVq843H4XNoaKVdEwnGYdtjrE UNZz3Ze3GsT6Yh/JYWrkjd3fvAOu/ufwn1VX8QrE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jarkko Sakkinen , Sumit Garg , Pankaj Gupta , David Gstir , Ahmad Fatoum , Sasha Levin , Michael Walle , John Ernberg Subject: [PATCH 5.15 016/102] KEYS: trusted: allow use of kernel RNG for key material Date: Mon, 16 Oct 2023 10:40:15 +0200 Message-ID: <20231016083954.121156438@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231016083953.689300946@linuxfoundation.org> References: <20231016083953.689300946@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ahmad Fatoum [ Upstream commit fcd7c26901c83681532c6daac599e53d4df11738 ] The two existing trusted key sources don't make use of the kernel RNG, but instead let the hardware doing the sealing/unsealing also generate the random key material. However, both users and future backends may want to place less trust into the quality of the trust source's random number generator and instead reuse the kernel entropy pool, which can be seeded from multiple entropy sources. Make this possible by adding a new trusted.rng parameter, that will force use of the kernel RNG. In its absence, it's up to the trust source to decide, which random numbers to use, maintaining the existing behavior. Suggested-by: Jarkko Sakkinen Acked-by: Sumit Garg Acked-by: Pankaj Gupta Reviewed-by: David Gstir Reviewed-by: Pankaj Gupta Reviewed-by: Jarkko Sakkinen Tested-by: Pankaj Gupta Tested-by: Michael Walle # on ls1028a (non-E and E) Tested-by: John Ernberg # iMX8QXP Signed-off-by: Ahmad Fatoum Signed-off-by: Jarkko Sakkinen Stable-dep-of: 01bbafc63b65 ("KEYS: trusted: Remove redundant static calls usage") Signed-off-by: Sasha Levin --- .../admin-guide/kernel-parameters.txt | 10 ++++++ .../security/keys/trusted-encrypted.rst | 20 ++++++----- include/keys/trusted-type.h | 2 +- security/keys/trusted-keys/trusted_core.c | 35 ++++++++++++++++++- 4 files changed, 57 insertions(+), 10 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 2cd4d66ab64c2..34b093e7f8910 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -5920,6 +5920,16 @@ first trust source as a backend which is initialized successfully during iteration. + trusted.rng= [KEYS] + Format: + The RNG used to generate key material for trusted keys. + Can be one of: + - "kernel" + - the same value as trusted.source: "tpm" or "tee" + - "default" + If not specified, "default" is used. In this case, + the RNG's choice is left to each individual trust source. + tsc= Disable clocksource stability checks for TSC. Format: [x86] reliable: mark tsc clocksource as reliable, this diff --git a/Documentation/security/keys/trusted-encrypted.rst b/Documentation/security/keys/trusted-encrypted.rst index 80d5a5af62a1d..99cf34d7c025b 100644 --- a/Documentation/security/keys/trusted-encrypted.rst +++ b/Documentation/security/keys/trusted-encrypted.rst @@ -87,22 +87,26 @@ Key Generation Trusted Keys ------------ -New keys are created from random numbers generated in the trust source. They -are encrypted/decrypted using a child key in the storage key hierarchy. -Encryption and decryption of the child key must be protected by a strong -access control policy within the trust source. +New keys are created from random numbers. They are encrypted/decrypted using +a child key in the storage key hierarchy. Encryption and decryption of the +child key must be protected by a strong access control policy within the +trust source. The random number generator in use differs according to the +selected trust source: - * TPM (hardware device) based RNG + * TPM: hardware device based RNG - Strength of random numbers may vary from one device manufacturer to - another. + Keys are generated within the TPM. Strength of random numbers may vary + from one device manufacturer to another. - * TEE (OP-TEE based on Arm TrustZone) based RNG + * TEE: OP-TEE based on Arm TrustZone based RNG RNG is customizable as per platform needs. It can either be direct output from platform specific hardware RNG or a software based Fortuna CSPRNG which can be seeded via multiple entropy sources. +Users may override this by specifying ``trusted.rng=kernel`` on the kernel +command-line to override the used RNG with the kernel's random number pool. + Encrypted Keys -------------- diff --git a/include/keys/trusted-type.h b/include/keys/trusted-type.h index d89fa2579ac05..4eb64548a74f1 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 9b9d3ef79cbe3..79806594384e3 100644 --- a/security/keys/trusted-keys/trusted_core.c +++ b/security/keys/trusted-keys/trusted_core.c @@ -16,12 +16,17 @@ #include #include #include +#include #include #include #include #include #include +static char *trusted_rng = "default"; +module_param_named(rng, trusted_rng, charp, 0); +MODULE_PARM_DESC(rng, "Select trusted key RNG"); + static char *trusted_key_source; module_param_named(source, trusted_key_source, charp, 0); MODULE_PARM_DESC(source, "Select trusted keys source (tpm or tee)"); @@ -312,8 +317,14 @@ struct key_type key_type_trusted = { }; EXPORT_SYMBOL_GPL(key_type_trusted); +static int kernel_get_random(unsigned char *key, size_t key_len) +{ + return get_random_bytes_wait(key, key_len) ?: key_len; +} + static int __init init_trusted(void) { + int (*get_random)(unsigned char *key, size_t key_len); int i, ret = 0; for (i = 0; i < ARRAY_SIZE(trusted_key_sources); i++) { @@ -322,6 +333,28 @@ static int __init init_trusted(void) strlen(trusted_key_sources[i].name))) continue; + /* + * We always support trusted.rng="kernel" and "default" as + * well as trusted.rng=$trusted.source if the trust source + * defines its own get_random callback. + */ + get_random = trusted_key_sources[i].ops->get_random; + if (trusted_rng && strcmp(trusted_rng, "default")) { + if (!strcmp(trusted_rng, "kernel")) { + get_random = kernel_get_random; + } else if (strcmp(trusted_rng, trusted_key_sources[i].name) || + !get_random) { + pr_warn("Unsupported RNG. Supported: kernel"); + if (get_random) + pr_cont(", %s", trusted_key_sources[i].name); + pr_cont(", default\n"); + return -EINVAL; + } + } + + if (!get_random) + get_random = kernel_get_random; + static_call_update(trusted_key_init, trusted_key_sources[i].ops->init); static_call_update(trusted_key_seal, @@ -329,7 +362,7 @@ static int __init init_trusted(void) static_call_update(trusted_key_unseal, trusted_key_sources[i].ops->unseal); static_call_update(trusted_key_get_random, - trusted_key_sources[i].ops->get_random); + get_random); static_call_update(trusted_key_exit, trusted_key_sources[i].ops->exit); migratable = trusted_key_sources[i].ops->migratable; -- 2.40.1