From patchwork Mon May 24 02:15:38 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: 12275331 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,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 88B99C47080 for ; Mon, 24 May 2021 02:16:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 64D4D61104 for ; Mon, 24 May 2021 02:16:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232192AbhEXCSB (ORCPT ); Sun, 23 May 2021 22:18:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37820 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232220AbhEXCSA (ORCPT ); Sun, 23 May 2021 22:18:00 -0400 Received: from mail-pj1-x102d.google.com (mail-pj1-x102d.google.com [IPv6:2607:f8b0:4864:20::102d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CC54DC061756; Sun, 23 May 2021 19:16:32 -0700 (PDT) Received: by mail-pj1-x102d.google.com with SMTP id g24so13935343pji.4; Sun, 23 May 2021 19:16:32 -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=UBiJbYx+TFhdZnz2kDV8TR+XeoXFYzdw3Kf+pNYHilA=; b=ORpuQi74kKWQVsjKuppO+52pIPLmNRkVpTzWysfLVp808qRwoXbetuhr4ijdKC4GCS asKHqyQrgNIEzrk8Xb4OkUGcC41mvwrKNqrkKc50OpLLvcgLJCFxUmib5gOAcuSb9nRF 8dP0BRDQqdUyJEPhCGo6gE2kXJeu5JNwpKoGI0+5o9RYv/LZuje5ZCbXbzdjXyYh7idB UM+ILrNPOP+VgtabH9JykjFIdL0TUfIdMTpACIt2vl5XjfAjXVjANNXYFyGrI0itOOAA sTW38lFE7CJkSd2AgRjit//fLkCvVqwDxodsDI/2/fZGv5SgqyfI8E+KxSsB2p+CHxDj FAUw== 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=UBiJbYx+TFhdZnz2kDV8TR+XeoXFYzdw3Kf+pNYHilA=; b=qMm3V8KQIUZAjbCE2yZK6LnSufg61WbsM/YKZdvy40wD/fgJhJI5PI1Iw8N7TLiG6l 1CxV+K55eNAXirOHZsHWQ9GNzFpsxs0E89ioW21UcpUXCwmmHNzKG2wzGHgZ/pmSOWxn krm+RQTCnbWvh6EpGmJYN5l2BAz18bSaM4hGZnvOhY3/bGfUkmsp84kN5r73+SOqh99k 84DI8Vh71UKxl21y4BfM4AN+fmK6r3iWG1kaCJcubEz5AeVXXhhP52AGCdPoXLU+MoDU KeQZa+akVI9/ToYGkSJHEm5Sf9egJuptTMVvluNCKQHecL/Q9jBY7J9U2sUcb+xHrXjB n7eQ== X-Gm-Message-State: AOAM531GUV1/J5ZZzgiANeVmEHNEhvo+8Z4K1SFoVES62LB7vmd2YWyq Q/j61sS6PE73zNqQd1JpjWQ= X-Google-Smtp-Source: ABdhPJzVOjdCl10j6SzLc3r0yZyxZgupBqpIMoz1ijfzxk/v2gIU5y9PZrbOB+Rlj1jiNccLSI04wg== X-Received: by 2002:a17:902:8346:b029:ef:5162:721e with SMTP id z6-20020a1709028346b02900ef5162721emr23099420pln.50.1621822592218; Sun, 23 May 2021 19:16:32 -0700 (PDT) Received: from linux-l9pv.suse ([124.11.22.254]) by smtp.gmail.com with ESMTPSA id h1sm9474960pfh.72.2021.05.23.19.16.26 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Sun, 23 May 2021 19:16:31 -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 v8,2/4] PKCS#7: Check codeSigning EKU for kernel module and kexec pe verification Date: Mon, 24 May 2021 10:15:38 +0800 Message-Id: <20210524021540.18736-3-jlee@suse.com> X-Mailer: git-send-email 2.12.3 In-Reply-To: <20210524021540.18736-1-jlee@suse.com> References: <20210524021540.18736-1-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 when verifying signature of kernel module or kexec PE binary in PKCS#7. Signed-off-by: "Lee, Chun-Yi" --- certs/blacklist.c | 6 +++-- certs/system_keyring.c | 4 ++-- crypto/asymmetric_keys/Kconfig | 9 ++++++++ crypto/asymmetric_keys/pkcs7_trust.c | 43 +++++++++++++++++++++++++++++++++--- include/crypto/pkcs7.h | 4 +++- include/keys/system_keyring.h | 7 ++++-- 6 files changed, 63 insertions(+), 10 deletions(-) diff --git a/certs/blacklist.c b/certs/blacklist.c index c9a435b15af4..a4ef26286584 100644 --- a/certs/blacklist.c +++ b/certs/blacklist.c @@ -16,6 +16,7 @@ #include #include #include +#include #include "blacklist.h" #include "common.h" @@ -181,11 +182,12 @@ int add_key_to_revocation_list(const char *data, size_t size) * is_key_on_revocation_list - Determine if the key for a PKCS#7 message is revoked * @pkcs7: The PKCS#7 message to check */ -int is_key_on_revocation_list(struct pkcs7_message *pkcs7) +int is_key_on_revocation_list(struct pkcs7_message *pkcs7, + enum key_being_used_for usage) { int ret; - ret = pkcs7_validate_trust(pkcs7, blacklist_keyring); + ret = pkcs7_validate_trust(pkcs7, blacklist_keyring, usage, false); if (ret == 0) return -EKEYREJECTED; diff --git a/certs/system_keyring.c b/certs/system_keyring.c index 692365dee2bd..394cf4e0feed 100644 --- a/certs/system_keyring.c +++ b/certs/system_keyring.c @@ -221,13 +221,13 @@ int verify_pkcs7_message_sig(const void *data, size_t len, goto error; } - ret = is_key_on_revocation_list(pkcs7); + ret = is_key_on_revocation_list(pkcs7, usage); if (ret != -ENOKEY) { pr_devel("PKCS#7 platform key is on revocation list\n"); goto error; } } - ret = pkcs7_validate_trust(pkcs7, trusted_keys); + ret = pkcs7_validate_trust(pkcs7, trusted_keys, usage, true); 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..c6ebf3e6adfd 100644 --- a/crypto/asymmetric_keys/pkcs7_trust.c +++ b/crypto/asymmetric_keys/pkcs7_trust.c @@ -16,12 +16,40 @@ #include #include "pkcs7_parser.h" +#ifdef CONFIG_CHECK_CODESIGN_EKU +static bool check_eku_by_usage(struct key *key, enum key_being_used_for usage) +{ + struct public_key *public_key = key->payload.data[asym_crypto]; + bool ret = true; + + switch (usage) { + case VERIFYING_MODULE_SIGNATURE: + case VERIFYING_KEXEC_PE_SIGNATURE: + ret = !!(public_key->eku & EKU_codeSigning); + if (!ret) + pr_warn("The signer '%s' key is not CodeSigning\n", + key->description); + break; + default: + break; + } + return ret; +} +#else +static bool check_eku_by_usage(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, + bool check_eku) { struct public_key_signature *sig = sinfo->sig; struct x509_certificate *x509, *last = NULL, *p; @@ -112,6 +140,10 @@ static int pkcs7_validate_trust_one(struct pkcs7_message *pkcs7, return -ENOKEY; matched: + if (check_eku && !check_eku_by_usage(key, usage)) { + key_put(key); + return -ENOKEY; + } ret = verify_signature(key, sig); key_put(key); if (ret < 0) { @@ -135,6 +167,8 @@ 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. + * @check_eku: Check EKU (Extended Key Usage) * * Validate that the certificate chain inside the PKCS#7 message intersects * keys we already know and trust. @@ -156,7 +190,9 @@ 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, + bool check_eku) { struct pkcs7_signed_info *sinfo; struct x509_certificate *p; @@ -167,7 +203,8 @@ 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, check_eku); switch (ret) { case -ENOKEY: continue; diff --git a/include/crypto/pkcs7.h b/include/crypto/pkcs7.h index 38ec7f5f9041..5d87b8a02f79 100644 --- a/include/crypto/pkcs7.h +++ b/include/crypto/pkcs7.h @@ -30,7 +30,9 @@ 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, + bool check_eku); /* * pkcs7_verify.c diff --git a/include/keys/system_keyring.h b/include/keys/system_keyring.h index 6acd3cf13a18..434a9b41d3a5 100644 --- a/include/keys/system_keyring.h +++ b/include/keys/system_keyring.h @@ -9,6 +9,7 @@ #define _KEYS_SYSTEM_KEYRING_H #include +#include #ifdef CONFIG_SYSTEM_TRUSTED_KEYRING @@ -59,13 +60,15 @@ static inline int is_binary_blacklisted(const u8 *hash, size_t hash_len) #ifdef CONFIG_SYSTEM_REVOCATION_LIST extern int add_key_to_revocation_list(const char *data, size_t size); -extern int is_key_on_revocation_list(struct pkcs7_message *pkcs7); +extern int is_key_on_revocation_list(struct pkcs7_message *pkcs7, + enum key_being_used_for usage); #else static inline int add_key_to_revocation_list(const char *data, size_t size) { return 0; } -static inline int is_key_on_revocation_list(struct pkcs7_message *pkcs7) +static inline int is_key_on_revocation_list(struct pkcs7_message *pkcs7, + enum key_being_used_for usage) { return -ENOKEY; }