From patchwork Tue Oct 20 06:50:01 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chun-Yi Lee X-Patchwork-Id: 11845843 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 7835616C0 for ; Tue, 20 Oct 2020 06:50:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4DCE2223BF for ; Tue, 20 Oct 2020 06:50:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="dzRGjCJO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404595AbgJTGun (ORCPT ); Tue, 20 Oct 2020 02:50:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53594 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404594AbgJTGum (ORCPT ); Tue, 20 Oct 2020 02:50:42 -0400 Received: from mail-pf1-x443.google.com (mail-pf1-x443.google.com [IPv6:2607:f8b0:4864:20::443]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 29F1FC061755; Mon, 19 Oct 2020 23:50:41 -0700 (PDT) Received: by mail-pf1-x443.google.com with SMTP id e7so612749pfn.12; Mon, 19 Oct 2020 23:50:41 -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=Mrea4LjAjlkriBDNrlEPZxK+wRxK9ddZNkjAKVpkbEc=; b=dzRGjCJOlyKQf3KF8xPwNR5M6QOjvfsdyIwzGUsWDVJoy19f2fRhYG2AhzZlKRkLmZ Cufzy355gF48EGwziQehtmEN7ic0LkRWsqQuTQ/JTZDLDhprOnY8XATOgULW0Z/tn0mW jhqdUFTraEpn5e2iFyDtt81vrog7K1DlxNDYHo0DUqRrtKxq/420ytSEIoMOWGx6zgLS iSeVvNISiOviIjKETk1gW3SPQgOKzRYok8AnV4peZjMhOlGymc1OPIMydbjMNcl3rHar yOQ+W9bOkWmHpAAHerD1dCdOzbeBXHHBSbfGGP7tflas+Xev0gsZNzPisdnc0Xx6P+ek Pimg== 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=Mrea4LjAjlkriBDNrlEPZxK+wRxK9ddZNkjAKVpkbEc=; b=TEXh6MEVEDKdPy1NmBumiK+VNLYaG6Gn9A0wwcwp26LnmKUdzE8gHLJvsibkgRAz8v VNoeG0heWgfELpaLlt5uwgIwc12rAGVEhT2181WUCatkSckmEBT9blBj9Q3SrwMeM7E3 Nks1pMphDdCJYMh3j3caEGROZ+npvNCMRet779fve38wOTjwuRA18DJnjPVIA1VN/T4F 1wsFdelS3Hlk75xx6PGhcqBNrzVq+l7FxWtklbZ7uZ7cnQ6BpPF9Nleb1HN1ii4Kceum wI0x6xIL6C5c0M/3sf61XJWCxVoQA3POOVKSIclO7jkS/12VreCdXWrj/qDQL2+hXo5N WOnA== X-Gm-Message-State: AOAM533IRJ5hdW0rB/cYfyoShV0W5SD5Pvd4RmpHXIAQphFXqF5CMmXs IzFQ8BZLOYu6xEIyZM72d/43zEMdvHTmzg== X-Google-Smtp-Source: ABdhPJxQXxuMfSlxGpGrzojxEZ82apkCkU7/lUvcU9VuuwWXZmhtrbL73KSO1E8n/PqqjhP1rtQLSA== X-Received: by 2002:a63:f908:: with SMTP id h8mr1488419pgi.203.1603176640723; Mon, 19 Oct 2020 23:50:40 -0700 (PDT) Received: from linux-l9pv.suse ([124.11.22.254]) by smtp.gmail.com with ESMTPSA id c203sm1026346pfb.96.2020.10.19.23.50.38 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 19 Oct 2020 23:50:40 -0700 (PDT) From: "Lee, Chun-Yi" X-Google-Original-From: "Lee, Chun-Yi" To: David Howells Cc: Herbert Xu , "David S . Miller" , keyrings@vger.kernel.org, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, "Lee, Chun-Yi" Subject: [RFC PATCH 2/2] PKCS#7: Check codeSigning EKU for kernel module and kexec pe verification Date: Tue, 20 Oct 2020 14:50:01 +0800 Message-Id: <20201020065001.13836-3-jlee@suse.com> X-Mailer: git-send-email 2.12.3 In-Reply-To: <20201020065001.13836-1-jlee@suse.com> References: <20201020065001.13836-1-jlee@suse.com> Precedence: bulk List-ID: X-Mailing-List: keyrings@vger.kernel.org This patch adds the logic for checking the CodeSigning extended key usage extenstion 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 | 10 ++++++++++ crypto/asymmetric_keys/pkcs7_trust.c | 37 +++++++++++++++++++++++++++++++++--- 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 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..6e3de0c3b5f0 100644 --- a/crypto/asymmetric_keys/Kconfig +++ b/crypto/asymmetric_keys/Kconfig @@ -96,4 +96,14 @@ 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 extension when verifying the signature in PKCS#7. It + affects kernel module verification and kexec PE binary verification + now. + 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