From patchwork Tue Feb 8 05:24:47 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 12738199 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 57CB3C4167E for ; Tue, 8 Feb 2022 05:33:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231794AbiBHFdN (ORCPT ); Tue, 8 Feb 2022 00:33:13 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36694 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233025AbiBHF1d (ORCPT ); Tue, 8 Feb 2022 00:27:33 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5959AC0401ED; Mon, 7 Feb 2022 21:27:32 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 1C2DBB8184D; Tue, 8 Feb 2022 05:27:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 94B2EC340EE; Tue, 8 Feb 2022 05:27:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1644298049; bh=nySwKR/PHIBHwyTLPaSdVAxC7gXi5UWq5MF9bzSt6xY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pPjXv23JFaSD8bLVgcMfzH+kQ30b6Jj5vVgrSi1yurD1Xq8KidYa7sPMMiuIBwkU4 t5Ers/gUj5ODos4GDROBJbc3qExRMewqsgwh4OBdL6Ug7BN/JusjojmeqMy/5w9GGW SH+RT0ShbZCzD1RXbEM7lmKuS4ilB2SO3JUpm5dXWxhDjEWebWiQvIfr2YPYk9stIb 4m44ZT852SXDx7lK5fxjGnBMOnsiY0ONZbHD8pZ1Ngle75WBkgINCVPx0TEAZEfJic hWuO8vzM0pWEqZ9vRgkxwGNFUKJ/kyt98LaRovgDjXx5+8Fw08E5rPCc4Lvr1iNkIM dAE5I+Kh9MLLg== From: Eric Biggers To: keyrings@vger.kernel.org, Jarkko Sakkinen , David Howells Cc: linux-crypto@vger.kernel.org, linux-integrity@vger.kernel.org, Stefan Berger , Gilad Ben-Yossef , Tianjia Zhang , Vitaly Chikunov , Mimi Zohar , stable@vger.kernel.org Subject: [PATCH v2 1/2] KEYS: asymmetric: enforce that sig algo matches key algo Date: Mon, 7 Feb 2022 21:24:47 -0800 Message-Id: <20220208052448.409152-2-ebiggers@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220208052448.409152-1-ebiggers@kernel.org> References: <20220208052448.409152-1-ebiggers@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: keyrings@vger.kernel.org From: Eric Biggers Most callers of public_key_verify_signature(), including most indirect callers via verify_signature() as well as pkcs7_verify_sig_chain(), don't check that public_key_signature::pkey_algo matches public_key::pkey_algo. These should always match. However, a malicious signature could intentionally declare an unintended algorithm. It is essential that such signatures be rejected outright, or that the algorithm of the *key* be used -- not the algorithm of the signature as that would allow attackers to choose the algorithm used. Currently, public_key_verify_signature() correctly uses the key's algorithm when deciding which akcipher to allocate. That's good. However, it uses the signature's algorithm when deciding whether to do the first step of SM2, which is incorrect. Also, v4.19 and older kernels used the signature's algorithm for the entire process. Prevent such errors by making public_key_verify_signature() enforce that the signature's algorithm (if given) matches the key's algorithm. Also remove two checks of this done by callers, which are now redundant. Cc: stable@vger.kernel.org Tested-by: Stefan Berger Tested-by: Tianjia Zhang Signed-off-by: Eric Biggers Reviewed-by: Vitaly Chikunov --- crypto/asymmetric_keys/pkcs7_verify.c | 6 ------ crypto/asymmetric_keys/public_key.c | 15 +++++++++++++++ crypto/asymmetric_keys/x509_public_key.c | 6 ------ 3 files changed, 15 insertions(+), 12 deletions(-) diff --git a/crypto/asymmetric_keys/pkcs7_verify.c b/crypto/asymmetric_keys/pkcs7_verify.c index 0b4d07aa8811..f94a1d1ad3a6 100644 --- a/crypto/asymmetric_keys/pkcs7_verify.c +++ b/crypto/asymmetric_keys/pkcs7_verify.c @@ -174,12 +174,6 @@ static int pkcs7_find_key(struct pkcs7_message *pkcs7, pr_devel("Sig %u: Found cert serial match X.509[%u]\n", sinfo->index, certix); - if (strcmp(x509->pub->pkey_algo, sinfo->sig->pkey_algo) != 0) { - pr_warn("Sig %u: X.509 algo and PKCS#7 sig algo don't match\n", - sinfo->index); - continue; - } - sinfo->signer = x509; return 0; } diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c index 4fefb219bfdc..e36213945686 100644 --- a/crypto/asymmetric_keys/public_key.c +++ b/crypto/asymmetric_keys/public_key.c @@ -325,6 +325,21 @@ int public_key_verify_signature(const struct public_key *pkey, BUG_ON(!sig); BUG_ON(!sig->s); + /* + * If the signature specifies a public key algorithm, it *must* match + * the key's actual public key algorithm. + * + * Small exception: ECDSA signatures don't specify the curve, but ECDSA + * keys do. So the strings can mismatch slightly in that case: + * "ecdsa-nist-*" for the key, but "ecdsa" for the signature. + */ + if (sig->pkey_algo) { + if (strcmp(pkey->pkey_algo, sig->pkey_algo) != 0 && + (strncmp(pkey->pkey_algo, "ecdsa-", 6) != 0 || + strcmp(sig->pkey_algo, "ecdsa") != 0)) + return -EKEYREJECTED; + } + ret = software_key_determine_akcipher(sig->encoding, sig->hash_algo, pkey, alg_name); diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c index fe14cae115b5..71cc1738fbfd 100644 --- a/crypto/asymmetric_keys/x509_public_key.c +++ b/crypto/asymmetric_keys/x509_public_key.c @@ -128,12 +128,6 @@ int x509_check_for_self_signed(struct x509_certificate *cert) goto out; } - ret = -EKEYREJECTED; - if (strcmp(cert->pub->pkey_algo, cert->sig->pkey_algo) != 0 && - (strncmp(cert->pub->pkey_algo, "ecdsa-", 6) != 0 || - strcmp(cert->sig->pkey_algo, "ecdsa") != 0)) - goto out; - ret = public_key_verify_signature(cert->pub, cert->sig); if (ret < 0) { if (ret == -ENOPKG) { From patchwork Tue Feb 8 05:24:48 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 12738201 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 E998EC43217 for ; Tue, 8 Feb 2022 05:33:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347429AbiBHFdQ (ORCPT ); Tue, 8 Feb 2022 00:33:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36690 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232896AbiBHF1d (ORCPT ); Tue, 8 Feb 2022 00:27:33 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5FD7FC0401DC; Mon, 7 Feb 2022 21:27:31 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id EFAE861586; Tue, 8 Feb 2022 05:27:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 107C1C340F3; Tue, 8 Feb 2022 05:27:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1644298050; bh=/+K9xJqNUbZi+7N8cFg9gue80UqlTLBuUSdgObEXWFM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Z7rRp2j1ZqpV2TpYaXY7gJ1fGd3/rz8go1vNnL7LLhFajnASfbccwm7ghLhfiuPo8 cspY+XndgYuFiHwUis9KwIApnSJ7WL6WC8o+CYE9fJ7SVTU4OHUKn5sCkGYAU2KFTN qeLv63wFZi5nMV4c8OBifjSJUd4MM4odt4R2FAIWD/80IerMETe2YIi6qK97MGDo4+ JdrJW6rxjVVBAINnsdihCisrPF5e1iKj4oQr/UzP4eKeDtmD4PnGDd47wY4EAVbc2O JkRn+Qt9Q/eAZ8h5x1OdjWhIhXnRTuu4dHQIW2s6YVvnpi4xFRb9vEA0QFvyrHwzSP 0/51eoviLja8A== From: Eric Biggers To: keyrings@vger.kernel.org, Jarkko Sakkinen , David Howells Cc: linux-crypto@vger.kernel.org, linux-integrity@vger.kernel.org, Stefan Berger , Gilad Ben-Yossef , Tianjia Zhang , Vitaly Chikunov , Mimi Zohar , stable@vger.kernel.org Subject: [PATCH v2 2/2] KEYS: asymmetric: properly validate hash_algo and encoding Date: Mon, 7 Feb 2022 21:24:48 -0800 Message-Id: <20220208052448.409152-3-ebiggers@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220208052448.409152-1-ebiggers@kernel.org> References: <20220208052448.409152-1-ebiggers@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: keyrings@vger.kernel.org From: Eric Biggers It is insecure to allow arbitrary hash algorithms and signature encodings to be used with arbitrary signature algorithms. Notably, ECDSA, ECRDSA, and SM2 all sign/verify raw hash values and don't disambiguate between different hash algorithms like RSA PKCS#1 v1.5 padding does. Therefore, they need to be restricted to certain sets of hash algorithms (ideally just one, but in practice small sets are used). Additionally, the encoding is an integral part of modern signature algorithms, and is not supposed to vary. Therefore, tighten the checks of hash_algo and encoding done by software_key_determine_akcipher(). Also rearrange the parameters to software_key_determine_akcipher() to put the public_key first, as this is the most important parameter and it often determines everything else. Fixes: 299f561a6693 ("x509: Add support for parsing x509 certs with ECDSA keys") Fixes: 215525639631 ("X.509: support OSCCA SM2-with-SM3 certificate verification") Fixes: 0d7a78643f69 ("crypto: ecrdsa - add EC-RDSA (GOST 34.10) algorithm") Cc: stable@vger.kernel.org Tested-by: Stefan Berger Tested-by: Tianjia Zhang Signed-off-by: Eric Biggers Reviewed-by: Vitaly Chikunov --- crypto/asymmetric_keys/public_key.c | 111 +++++++++++++++++++--------- 1 file changed, 76 insertions(+), 35 deletions(-) diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c index e36213945686..7c9e6be35c30 100644 --- a/crypto/asymmetric_keys/public_key.c +++ b/crypto/asymmetric_keys/public_key.c @@ -60,39 +60,83 @@ static void public_key_destroy(void *payload0, void *payload3) } /* - * Determine the crypto algorithm name. + * Given a public_key, and an encoding and hash_algo to be used for signing + * and/or verification with that key, determine the name of the corresponding + * akcipher algorithm. Also check that encoding and hash_algo are allowed. */ -static -int software_key_determine_akcipher(const char *encoding, - const char *hash_algo, - const struct public_key *pkey, - char alg_name[CRYPTO_MAX_ALG_NAME]) +static int +software_key_determine_akcipher(const struct public_key *pkey, + const char *encoding, const char *hash_algo, + char alg_name[CRYPTO_MAX_ALG_NAME]) { int n; - if (strcmp(encoding, "pkcs1") == 0) { - /* The data wangled by the RSA algorithm is typically padded - * and encoded in some manner, such as EMSA-PKCS1-1_5 [RFC3447 - * sec 8.2]. + if (!encoding) + return -EINVAL; + + if (strcmp(pkey->pkey_algo, "rsa") == 0) { + /* + * RSA signatures usually use EMSA-PKCS1-1_5 [RFC3447 sec 8.2]. + */ + if (strcmp(encoding, "pkcs1") == 0) { + if (!hash_algo) + n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME, + "pkcs1pad(%s)", + pkey->pkey_algo); + else + n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME, + "pkcs1pad(%s,%s)", + pkey->pkey_algo, hash_algo); + return n >= CRYPTO_MAX_ALG_NAME ? -EINVAL : 0; + } + if (strcmp(encoding, "raw") != 0) + return -EINVAL; + /* + * Raw RSA cannot differentiate between different hash + * algorithms. + */ + if (hash_algo) + return -EINVAL; + } else if (strncmp(pkey->pkey_algo, "ecdsa", 5) == 0) { + if (strcmp(encoding, "x962") != 0) + return -EINVAL; + /* + * ECDSA signatures are taken over a raw hash, so they don't + * differentiate between different hash algorithms. That means + * that the verifier should hard-code a specific hash algorithm. + * Unfortunately, in practice ECDSA is used with multiple SHAs, + * so we have to allow all of them and not just one. */ if (!hash_algo) - n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME, - "pkcs1pad(%s)", - pkey->pkey_algo); - else - n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME, - "pkcs1pad(%s,%s)", - pkey->pkey_algo, hash_algo); - return n >= CRYPTO_MAX_ALG_NAME ? -EINVAL : 0; - } - - if (strcmp(encoding, "raw") == 0 || - strcmp(encoding, "x962") == 0) { - strcpy(alg_name, pkey->pkey_algo); - return 0; + return -EINVAL; + if (strcmp(hash_algo, "sha1") != 0 && + strcmp(hash_algo, "sha224") != 0 && + strcmp(hash_algo, "sha256") != 0 && + strcmp(hash_algo, "sha384") != 0 && + strcmp(hash_algo, "sha512") != 0) + return -EINVAL; + } else if (strcmp(pkey->pkey_algo, "sm2") == 0) { + if (strcmp(encoding, "raw") != 0) + return -EINVAL; + if (!hash_algo) + return -EINVAL; + if (strcmp(hash_algo, "sm3") != 0) + return -EINVAL; + } else if (strcmp(pkey->pkey_algo, "ecrdsa") == 0) { + if (strcmp(encoding, "raw") != 0) + return -EINVAL; + if (!hash_algo) + return -EINVAL; + if (strcmp(hash_algo, "streebog256") != 0 && + strcmp(hash_algo, "streebog512") != 0) + return -EINVAL; + } else { + /* Unknown public key algorithm */ + return -ENOPKG; } - - return -ENOPKG; + if (strscpy(alg_name, pkey->pkey_algo, CRYPTO_MAX_ALG_NAME) < 0) + return -EINVAL; + return 0; } static u8 *pkey_pack_u32(u8 *dst, u32 val) @@ -113,9 +157,8 @@ static int software_key_query(const struct kernel_pkey_params *params, u8 *key, *ptr; int ret, len; - ret = software_key_determine_akcipher(params->encoding, - params->hash_algo, - pkey, alg_name); + ret = software_key_determine_akcipher(pkey, params->encoding, + params->hash_algo, alg_name); if (ret < 0) return ret; @@ -179,9 +222,8 @@ static int software_key_eds_op(struct kernel_pkey_params *params, pr_devel("==>%s()\n", __func__); - ret = software_key_determine_akcipher(params->encoding, - params->hash_algo, - pkey, alg_name); + ret = software_key_determine_akcipher(pkey, params->encoding, + params->hash_algo, alg_name); if (ret < 0) return ret; @@ -340,9 +382,8 @@ int public_key_verify_signature(const struct public_key *pkey, return -EKEYREJECTED; } - ret = software_key_determine_akcipher(sig->encoding, - sig->hash_algo, - pkey, alg_name); + ret = software_key_determine_akcipher(pkey, sig->encoding, + sig->hash_algo, alg_name); if (ret < 0) return ret;