From mboxrd@z Thu Jan 1 00:00:00 1970 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 C9C53C433FE for ; Tue, 5 Apr 2022 07:43:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231475AbiDEHpI (ORCPT ); Tue, 5 Apr 2022 03:45:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55418 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232089AbiDEHoV (ORCPT ); Tue, 5 Apr 2022 03:44:21 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EE8C196807; Tue, 5 Apr 2022 00:40:50 -0700 (PDT) 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 5C75EB81B18; Tue, 5 Apr 2022 07:40:49 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B9D09C340EE; Tue, 5 Apr 2022 07:40:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649144448; bh=S5JSbPs7QsysBWhnR3G8MjqokpkFfZdd3XOVDP5puGs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=m9leIdhCdY7KahLyWfcFyeYPv9Yp8mLtW/73CsvaP7VlVo68WQ0c0O03D+W7hRl1n zcViEQL5YG3TIyMgoDv0ygSBXeTb9fdpi5zURm8xbDZI9LhFsApheb69MJkGK+p3JC FYzxh0jCtLUqoivrgvTR293/LxEufzv33LGtJhe4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Stefan Berger , Tianjia Zhang , Eric Biggers , Vitaly Chikunov , Jarkko Sakkinen Subject: [PATCH 5.17 0047/1126] KEYS: asymmetric: enforce that sig algo matches key algo Date: Tue, 5 Apr 2022 09:13:14 +0200 Message-Id: <20220405070408.944532144@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220405070407.513532867@linuxfoundation.org> References: <20220405070407.513532867@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Eric Biggers commit 2abc9c246e0548e52985b10440c9ea3e9f65f793 upstream. 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 Reviewed-by: Jarkko Sakkinen Signed-off-by: Jarkko Sakkinen Signed-off-by: Greg Kroah-Hartman --- 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(-) --- 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_m 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; } --- a/crypto/asymmetric_keys/public_key.c +++ b/crypto/asymmetric_keys/public_key.c @@ -325,6 +325,21 @@ int public_key_verify_signature(const st 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); --- 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 x5 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) {