From patchwork Thu Apr 29 07:28:49 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Lee, Chun-Yi" X-Patchwork-Id: 429961 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=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 5DC63C43461 for ; Thu, 29 Apr 2021 07:29:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 27DC56143D for ; Thu, 29 Apr 2021 07:29:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239409AbhD2Had (ORCPT ); Thu, 29 Apr 2021 03:30:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60272 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239616AbhD2Hac (ORCPT ); Thu, 29 Apr 2021 03:30:32 -0400 Received: from mail-pj1-x1033.google.com (mail-pj1-x1033.google.com [IPv6:2607:f8b0:4864:20::1033]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 32DEBC06138D; Thu, 29 Apr 2021 00:29:14 -0700 (PDT) Received: by mail-pj1-x1033.google.com with SMTP id j6-20020a17090adc86b02900cbfe6f2c96so10495337pjv.1; Thu, 29 Apr 2021 00:29:14 -0700 (PDT) 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=2VAL6t0JhjYuENdb0/a6OoZ5pXUaFlWqPPwScBUiDow=; b=UdXmwskiwOU0DVaLuOM4b6FewZNzWff444sb7ueg0mJxjO/Ipzdw+hP4EiFhvU9om2 Qb+AM7wdWRbj6X0VtyrwSCUYuEJhKXxLmi/ALNYrdl3xlJWPIFry/88e96rcI+Rktn09 hXgMp57Utpq1gzSvP735oigoLVtQO4ZUG19bvrh4/KmW+emSUvDxaOGbssLbMCnKlBFG ZGkPHaSXKe2S+X/+iBXyUx+HhmWT5aW7o9YNA+RtUYoiO7kv7F3RkSK8XqeaHyHSmmmf rV5xIi1TsRVtCJLG1q01yT7pdnHtCeh86eo9DcJLRKnOEZaVVdayeC2KCxyBrXdhpi7l oapQ== 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=2VAL6t0JhjYuENdb0/a6OoZ5pXUaFlWqPPwScBUiDow=; b=dukEtA39e9ZZzCli3HfKfhmPaGOKtX//b3IIykJk2MhPIVVuwtXoL02ByudWR+h22h 6zeHtKeWbwQv6nIGncZMRNGnnSbO2EIV/MaYyXp2zgjwQ6A8OgNoWKSzNEQ62V+iquRi k3LAv7pY7CD7gJ5O4A83aidRDImM9++NqV9Gpke9BYSBhMYn4jphvtShnStasYv0rXPr YL58uNMJPfYZciZmLyP7xbBAtoZOvl0lu7AuuCwR+GT3IZxKb6D4gY1iNciWlmlBlFgp NYF5jd1GBeUJHXuMtMroAs0MkeZ9fLs8GZHLbeaFdEnfqEF3LmxyaKoGsJXISyXS1DQC mMkQ== X-Gm-Message-State: AOAM532zrEdR6sGCj5uXnXr8sflh6NTrWgQmVozt4VEAO+OVIwCxMlil VGQJ6R2ogx7cuZ/goQQEbng= X-Google-Smtp-Source: ABdhPJxoV/SG4BZSPLMQ97AcSJ4dQH3ewEH2DtmFl04AiqKFr2PnayjdrCVnyRbDp7/wo8NMzcpevg== X-Received: by 2002:a17:902:8f8d:b029:ea:e059:84a6 with SMTP id z13-20020a1709028f8db02900eae05984a6mr34788392plo.35.1619681353802; Thu, 29 Apr 2021 00:29:13 -0700 (PDT) Received: from linux-l9pv.suse ([124.11.22.254]) by smtp.gmail.com with ESMTPSA id z29sm1632085pga.52.2021.04.29.00.29.11 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 29 Apr 2021 00:29:13 -0700 (PDT) From: "Lee, Chun-Yi" X-Google-Original-From: "Lee, Chun-Yi" To: David Howells Cc: Herbert Xu , "David S . Miller" , Ben Boeckel , Randy Dunlap , Malte Gell , Varad Gautam , keyrings@vger.kernel.org, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, "Lee, Chun-Yi" Subject: [PATCH v6, 2/4] PKCS#7: Check codeSigning EKU for kernel module and kexec pe verification Date: Thu, 29 Apr 2021 15:28:49 +0800 Message-Id: <20210429072851.24057-3-jlee@suse.com> X-Mailer: git-send-email 2.12.3 In-Reply-To: <20210429072851.24057-1-jlee@suse.com> References: <20210429072851.24057-1-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 | 38 +++++++++++++++++++++++++++++++++--- include/crypto/pkcs7.h | 3 ++- 4 files changed, 47 insertions(+), 5 deletions(-) diff --git a/certs/system_keyring.c b/certs/system_keyring.c index 0c9a4795e847..302ca0555e75 100644 --- a/certs/system_keyring.c +++ b/certs/system_keyring.c @@ -206,7 +206,7 @@ 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 b531df2013c4..7c27bf81aca9 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) { @@ -135,6 +165,7 @@ static int pkcs7_validate_trust_one(struct pkcs7_message *pkcs7, * pkcs7_validate_trust - Validate PKCS#7 trust chain * @pkcs7: The PKCS#7 certificate to validate * @trust_keyring: Signing certificates to use as starting points + * @usage: The use to which the key is being put. * * Validate that the certificate chain inside the PKCS#7 message intersects * keys we already know and trust. @@ -156,7 +187,8 @@ 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 +199,7 @@ 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