From patchwork Thu Nov 5 04:24:06 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Lee, Chun-Yi" X-Patchwork-Id: 319456 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4E16DC388F9 for ; Thu, 5 Nov 2020 04:25:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E9B2120795 for ; Thu, 5 Nov 2020 04:25:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="i71nKCxm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730131AbgKEEZA (ORCPT ); Wed, 4 Nov 2020 23:25:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34976 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730078AbgKEEY7 (ORCPT ); Wed, 4 Nov 2020 23:24:59 -0500 Received: from mail-pg1-x542.google.com (mail-pg1-x542.google.com [IPv6:2607:f8b0:4864:20::542]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 202EEC0613CF; Wed, 4 Nov 2020 20:24:59 -0800 (PST) Received: by mail-pg1-x542.google.com with SMTP id x13so399577pgp.7; Wed, 04 Nov 2020 20:24:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=rEVQORojpxPILZoW25n2HNyuoMNfuJyQRA19mYILOf8=; b=i71nKCxm/Rk7Qe0vfqXmlNOIbt9fIuievRqcCn5TJ1yWIdb59otcj93oz7j+gpZZWo Bp6lTHoFkgmmVJDji7oItHa5kc9VjRnHjZzsPiy/LrWinbv+5uRpmvxIuhDnTMid3S3x x9JmlkWfqwTYLVEqsdgw1Shol9H+Mp4WsGw0er643fBik2QBf/oBlbKOXNg8BVHq1P7d eweO2JBa6jgeNWz99UIYx/pKdjGP0px9q+CsV9n/AZpXUCCjEIpKBze+wCLNFthZ8LuJ CySDEmIbmdVIhQxI03oDD+oIR2gX3i68ERDpDX2/L3OAVGtHDcT3nx+1ihH9vgWSyMue A8Iw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=rEVQORojpxPILZoW25n2HNyuoMNfuJyQRA19mYILOf8=; b=EFHxwh/aKzxhOhj40dQzqrXRW8Vl58l0Zs4S2FTh6O7awn9Ycn8z+tpwMznDWwDOfY ZyrJMOZ1k2ZzKzMH2OeB+OtiStfrR0n6uo0k9nGAvmoLu2vpEFBZxpMH5LbSQSW74SjX BOxBZsb6COLjNcRuxBi77N/iARbm7MKYWz/hq78QAYfX5NgCDcfRIFJECYAxQP9TOQPd hhnBKuQfCz2aipwmZHrs9yUFGDeC6bQSGuflmrk79xlAC6bVYfxxVbsjOEw+kJFLc6TY 3YHbJnGEBPOhw2pt6xQ/4TwoKYV7YSdrkb2DknqXOq+s2q4keDeEmeVUDO/rrVuJF/Qv F7pw== X-Gm-Message-State: AOAM5336vik3CNGFz6NYeb6Db1yYXQ1pt7G7FNm3qhYhGMthxT3+9jRg uDypJdr84Ztv73KtKZA9L/k= X-Google-Smtp-Source: ABdhPJxxSyyliKXbv7VU2uhEsbi4aEkX5Awvipq0CP4TmL0j/U/T8uSPpKMflgkHnq9+9ELOvhfBgQ== X-Received: by 2002:aa7:8b50:0:b029:18a:adb4:8411 with SMTP id i16-20020aa78b500000b029018aadb48411mr775573pfd.66.1604550298712; Wed, 04 Nov 2020 20:24:58 -0800 (PST) Received: from linux-l9pv.suse ([124.11.22.254]) by smtp.gmail.com with ESMTPSA id z22sm472782pfa.220.2020.11.04.20.24.55 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 04 Nov 2020 20:24:58 -0800 (PST) From: "Lee, Chun-Yi" X-Google-Original-From: "Lee, Chun-Yi" To: David Howells Cc: Herbert Xu , "David S . Miller" , Ben Boeckel , Randy Dunlap , keyrings@vger.kernel.org, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, "Lee, Chun-Yi" Subject: [PATCH v2 2/2] PKCS#7: Check codeSigning EKU for kernel module and kexec pe verification Date: Thu, 5 Nov 2020 12:24:06 +0800 Message-Id: <20201105042406.5783-3-jlee@suse.com> X-Mailer: git-send-email 2.12.3 In-Reply-To: <20201105042406.5783-1-jlee@suse.com> References: <20201105042406.5783-1-jlee@suse.com> Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org This patch adds the logic for checking the CodeSigning extended key usage when verifying signature of kernel module or kexec PE binary in PKCS#7. Signed-off-by: "Lee, Chun-Yi" --- certs/system_keyring.c | 2 +- crypto/asymmetric_keys/Kconfig | 9 +++++++++ crypto/asymmetric_keys/pkcs7_trust.c | 37 +++++++++++++++++++++++++++++++++--- include/crypto/pkcs7.h | 3 ++- 4 files changed, 46 insertions(+), 5 deletions(-) diff --git a/certs/system_keyring.c b/certs/system_keyring.c index 798291177186..4104f5465d8a 100644 --- a/certs/system_keyring.c +++ b/certs/system_keyring.c @@ -242,7 +242,7 @@ int verify_pkcs7_message_sig(const void *data, size_t len, goto error; } } - ret = pkcs7_validate_trust(pkcs7, trusted_keys); + ret = pkcs7_validate_trust(pkcs7, trusted_keys, usage); if (ret < 0) { if (ret == -ENOKEY) pr_devel("PKCS#7 signature not signed with a trusted key\n"); diff --git a/crypto/asymmetric_keys/Kconfig b/crypto/asymmetric_keys/Kconfig index 1f1f004dc757..1754812df989 100644 --- a/crypto/asymmetric_keys/Kconfig +++ b/crypto/asymmetric_keys/Kconfig @@ -96,4 +96,13 @@ config SIGNED_PE_FILE_VERIFICATION This option provides support for verifying the signature(s) on a signed PE binary. +config CHECK_CODESIGN_EKU + bool "Check codeSigning extended key usage" + depends on PKCS7_MESSAGE_PARSER=y + depends on SYSTEM_DATA_VERIFICATION + help + This option provides support for checking the codeSigning extended + key usage when verifying the signature in PKCS#7. It affects kernel + module verification and kexec PE binary verification. + endif # ASYMMETRIC_KEY_TYPE diff --git a/crypto/asymmetric_keys/pkcs7_trust.c b/crypto/asymmetric_keys/pkcs7_trust.c index 61af3c4d82cc..1d2318ff63db 100644 --- a/crypto/asymmetric_keys/pkcs7_trust.c +++ b/crypto/asymmetric_keys/pkcs7_trust.c @@ -16,12 +16,36 @@ #include #include "pkcs7_parser.h" +#ifdef CONFIG_CHECK_CODESIGN_EKU +static bool check_codesign_eku(struct key *key, + enum key_being_used_for usage) +{ + struct public_key *public_key = key->payload.data[asym_crypto]; + + switch (usage) { + case VERIFYING_MODULE_SIGNATURE: + case VERIFYING_KEXEC_PE_SIGNATURE: + return !!(public_key->eku & EKU_codeSigning); + default: + break; + } + return true; +} +#else +static bool check_codesign_eku(struct key *key, + enum key_being_used_for usage) +{ + return true; +} +#endif + /** * Check the trust on one PKCS#7 SignedInfo block. */ static int pkcs7_validate_trust_one(struct pkcs7_message *pkcs7, struct pkcs7_signed_info *sinfo, - struct key *trust_keyring) + struct key *trust_keyring, + enum key_being_used_for usage) { struct public_key_signature *sig = sinfo->sig; struct x509_certificate *x509, *last = NULL, *p; @@ -112,6 +136,12 @@ static int pkcs7_validate_trust_one(struct pkcs7_message *pkcs7, return -ENOKEY; matched: + if (!check_codesign_eku(key, usage)) { + pr_warn("sinfo %u: The signer %x key is not CodeSigning\n", + sinfo->index, key_serial(key)); + key_put(key); + return -ENOKEY; + } ret = verify_signature(key, sig); key_put(key); if (ret < 0) { @@ -156,7 +186,8 @@ static int pkcs7_validate_trust_one(struct pkcs7_message *pkcs7, * May also return -ENOMEM. */ int pkcs7_validate_trust(struct pkcs7_message *pkcs7, - struct key *trust_keyring) + struct key *trust_keyring, + enum key_being_used_for usage) { struct pkcs7_signed_info *sinfo; struct x509_certificate *p; @@ -167,7 +198,7 @@ int pkcs7_validate_trust(struct pkcs7_message *pkcs7, p->seen = false; for (sinfo = pkcs7->signed_infos; sinfo; sinfo = sinfo->next) { - ret = pkcs7_validate_trust_one(pkcs7, sinfo, trust_keyring); + ret = pkcs7_validate_trust_one(pkcs7, sinfo, trust_keyring, usage); switch (ret) { case -ENOKEY: continue; diff --git a/include/crypto/pkcs7.h b/include/crypto/pkcs7.h index 38ec7f5f9041..b3b48240ba73 100644 --- a/include/crypto/pkcs7.h +++ b/include/crypto/pkcs7.h @@ -30,7 +30,8 @@ extern int pkcs7_get_content_data(const struct pkcs7_message *pkcs7, * pkcs7_trust.c */ extern int pkcs7_validate_trust(struct pkcs7_message *pkcs7, - struct key *trust_keyring); + struct key *trust_keyring, + enum key_being_used_for usage); /* * pkcs7_verify.c