From patchwork Mon Feb 21 12:10:51 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nicolai Stange X-Patchwork-Id: 544495 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 ED417C4332F for ; Mon, 21 Feb 2022 12:14:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1357621AbiBUMOd (ORCPT ); Mon, 21 Feb 2022 07:14:33 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:42146 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1357618AbiBUMOM (ORCPT ); Mon, 21 Feb 2022 07:14:12 -0500 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CA29C21E34; Mon, 21 Feb 2022 04:11:20 -0800 (PST) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 8760C2113B; Mon, 21 Feb 2022 12:11:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1645445479; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=RbWEdeLEnpwK+SZUqqlXr7ZVFlur6T5ifGlGBjkwCrc=; b=Z1Om9vgvR6r0tcLJIoivMN0aEkEDLt7UhDUUTD91y1A7M0roRW7XjUtopJEhldMtr0/m7D zRUCQon2Lb6UN8LWNeyvyvNZZU6jpkOox0DUgEZ6bTyKofvhAw7/v0YoxDfdWIRARMkGcH d9GA+UCw8GAEm2st21XBGa6IovpgmQA= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1645445479; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=RbWEdeLEnpwK+SZUqqlXr7ZVFlur6T5ifGlGBjkwCrc=; b=O+u+xqievn4ayza3E1dH3NH+nM7M90IFjfVgByjGv6zPXyEbiqPyKf0dJ55v99shK/lxw/ OJEEFYvOHrp+Y0Cg== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 70CD513A9C; Mon, 21 Feb 2022 12:11:19 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id sUz1GWeBE2J6WwAAMHmgww (envelope-from ); Mon, 21 Feb 2022 12:11:19 +0000 From: Nicolai Stange To: Herbert Xu , "David S. Miller" Cc: =?utf-8?q?Stephan_M=C3=BCller?= , Hannes Reinecke , Torsten Duwe , David Howells , Jarkko Sakkinen , linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, keyrings@vger.kernel.org, Nicolai Stange Subject: [PATCH v4 05/15] crypto: dh - split out deserialization code from crypto_dh_decode() Date: Mon, 21 Feb 2022 13:10:51 +0100 Message-Id: <20220221121101.1615-6-nstange@suse.de> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20220221121101.1615-1-nstange@suse.de> References: <20220221121101.1615-1-nstange@suse.de> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org A subsequent commit will introduce "dh" wrapping templates of the form "ffdhe2048(dh)", "ffdhe3072(dh)" and so on in order to provide built-in support for the well-known safe-prime ffdhe group parameters specified in RFC 7919. Those templates' ->set_secret() will wrap the inner "dh" implementation's ->set_secret() and set the ->p and ->g group parameters as appropriate on the way inwards. More specifically, - A ffdheXYZ(dh) user would call crypto_dh_encode() on a struct dh instance having ->p == ->g == NULL as well as ->p_size == ->g_size == 0 and pass the resulting buffer to the outer ->set_secret(). - This outer ->set_secret() would then decode the struct dh via crypto_dh_decode_key(), set ->p, ->g, ->p_size as well as ->g_size as appropriate for the group in question and encode the struct dh again before passing it further down to the inner "dh"'s ->set_secret(). The problem is that crypto_dh_decode_key() implements some basic checks which would reject parameter sets with ->p_size == 0 and thus, the ffdheXYZ templates' ->set_secret() cannot use it as-is for decoding the passed buffer. As the inner "dh"'s ->set_secret() will eventually conduct said checks on the final parameter set anyway, the outer ->set_secret() really only needs the decoding functionality. Split out the pure struct dh decoding part from crypto_dh_decode_key() into the new __crypto_dh_decode_key(). __crypto_dh_decode_key() gets defined in crypto/dh_helper.c, but will have to get called from crypto/dh.c and thus, its declaration must be somehow made available to the latter. Strictly speaking, __crypto_dh_decode_key() is internal to the dh_generic module, yet it would be a bit over the top to introduce a new header like e.g. include/crypto/internal/dh.h containing just a single prototype. Add the __crypto_dh_decode_key() declaration to include/crypto/dh.h instead. Provide a proper kernel-doc annotation, even though __crypto_dh_decode_key() is purposedly not on the function list specified in Documentation/crypto/api-kpp.rst. Signed-off-by: Nicolai Stange --- crypto/dh_helper.c | 27 +++++++++++++++++++-------- include/crypto/dh.h | 16 ++++++++++++++++ 2 files changed, 35 insertions(+), 8 deletions(-) diff --git a/crypto/dh_helper.c b/crypto/dh_helper.c index aabc91e4f63f..2d499879328b 100644 --- a/crypto/dh_helper.c +++ b/crypto/dh_helper.c @@ -63,7 +63,7 @@ int crypto_dh_encode_key(char *buf, unsigned int len, const struct dh *params) } EXPORT_SYMBOL_GPL(crypto_dh_encode_key); -int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params) +int __crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params) { const u8 *ptr = buf; struct kpp_secret secret; @@ -81,6 +81,24 @@ int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params) if (secret.len != crypto_dh_key_len(params)) return -EINVAL; + /* Don't allocate memory. Set pointers to data within + * the given buffer + */ + params->key = (void *)ptr; + params->p = (void *)(ptr + params->key_size); + params->g = (void *)(ptr + params->key_size + params->p_size); + + return 0; +} + +int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params) +{ + int err; + + err = __crypto_dh_decode_key(buf, len, params); + if (err) + return err; + /* * Don't permit the buffer for 'key' or 'g' to be larger than 'p', since * some drivers assume otherwise. @@ -89,13 +107,6 @@ int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params) params->g_size > params->p_size) return -EINVAL; - /* Don't allocate memory. Set pointers to data within - * the given buffer - */ - params->key = (void *)ptr; - params->p = (void *)(ptr + params->key_size); - params->g = (void *)(ptr + params->key_size + params->p_size); - /* * Don't permit 'p' to be 0. It's not a prime number, and it's subject * to corner cases such as 'mod 0' being undefined or diff --git a/include/crypto/dh.h b/include/crypto/dh.h index 67f3f6bca527..7b863e911cb4 100644 --- a/include/crypto/dh.h +++ b/include/crypto/dh.h @@ -79,4 +79,20 @@ int crypto_dh_encode_key(char *buf, unsigned int len, const struct dh *params); */ int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params); +/** + * __crypto_dh_decode_key() - decode a private key without parameter checks + * @buf: Buffer holding a packet key that should be decoded + * @len: Length of the packet private key buffer + * @params: Buffer allocated by the caller that is filled with the + * unpacked DH private key. + * + * Internal function providing the same services as the exported + * crypto_dh_decode_key(), but without any of those basic parameter + * checks conducted by the latter. + * + * Return: -EINVAL if buffer has insufficient size, 0 on success + */ +int __crypto_dh_decode_key(const char *buf, unsigned int len, + struct dh *params); + #endif