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 52595C43217 for ; Mon, 13 Dec 2021 18:06:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238160AbhLMSGV (ORCPT ); Mon, 13 Dec 2021 13:06:21 -0500 Received: from smtp-out2.suse.de ([195.135.220.29]:48726 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231917AbhLMSGT (ORCPT ); Mon, 13 Dec 2021 13:06:19 -0500 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 8C8D71F3B9; Mon, 13 Dec 2021 18:06:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1639418776; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=qWxzseejwZyTZ++HZonSBD5ITvu3/IfjEy9A76Uqkn4=; b=kB4bbvIeiQDG4KZp40WnqvXCnCB4Rdybk77ruhyUFtfVewTOhpuI63qYS6wtHGe+nqxkYI JFDQ6oQ5AAy8Li6vYLF9EesA1ABUWHXpYq7rHXFyKAGhtskOjMduB4u+yNt71wlI3U6NkG Zwg6iEuKykO5MGot2faYd2ZWE5HS4s4= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1639418776; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=qWxzseejwZyTZ++HZonSBD5ITvu3/IfjEy9A76Uqkn4=; b=PVFq5fsrpjsQQyZPIhYIBlk2Xjufl+SPQnSyz1lfIN9R31Lqt3c3GkwXpmJEm/Q6n7bWoW SZ5fQfbtmxtxdeBA== Received: from kunlun.suse.cz (unknown [10.100.128.76]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id C4E98A3B84; Mon, 13 Dec 2021 18:06:12 +0000 (UTC) Date: Mon, 13 Dec 2021 19:06:11 +0100 From: Michal =?iso-8859-1?Q?Such=E1nek?= To: Philipp Rudo Cc: keyrings@vger.kernel.org, kexec@lists.infradead.org, Mimi Zohar , Nayna , Rob Herring , linux-s390@vger.kernel.org, Vasily Gorbik , Lakshmi Ramasubramanian , Heiko Carstens , Jessica Yu , linux-kernel@vger.kernel.org, David Howells , Christian Borntraeger , Luis Chamberlain , Paul Mackerras , Hari Bathini , Alexander Gordeev , linuxppc-dev@lists.ozlabs.org, Frank van der Linden , Thiago Jung Bauermann , Daniel Axtens , buendgen@de.ibm.com, Michael Ellerman , Benjamin Herrenschmidt , Christian Borntraeger , Herbert Xu , "David S. Miller" , Dmitry Kasatkin , James Morris , "Serge E. Hallyn" , Sven Schnelle , Baoquan He , linux-crypto@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org Subject: Re: [PATCH v2 6/6] module: Move duplicate mod_check_sig users code to mod_parse_sig Message-ID: <20211213180611.GU117207@kunlun.suse.cz> References: <20211207171034.0b782d82@rhtmp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211207171034.0b782d82@rhtmp> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Tue, Dec 07, 2021 at 05:10:34PM +0100, Philipp Rudo wrote: > Hi Michal, > > On Thu, 25 Nov 2021 19:02:44 +0100 > Michal Suchanek wrote: > > > Multiple users of mod_check_sig check for the marker, then call > > mod_check_sig, extract signature length, and remove the signature. > > > > Put this code in one place together with mod_check_sig. > > > > Signed-off-by: Michal Suchanek > > --- > > include/linux/module_signature.h | 1 + > > kernel/module_signature.c | 56 ++++++++++++++++++++++++++++- > > kernel/module_signing.c | 26 +++----------- > > security/integrity/ima/ima_modsig.c | 22 ++---------- > > 4 files changed, 63 insertions(+), 42 deletions(-) > > > > diff --git a/include/linux/module_signature.h b/include/linux/module_signature.h > > index 7eb4b00381ac..1343879b72b3 100644 > > --- a/include/linux/module_signature.h > > +++ b/include/linux/module_signature.h > > @@ -42,5 +42,6 @@ struct module_signature { > > > > int mod_check_sig(const struct module_signature *ms, size_t file_len, > > const char *name); > > +int mod_parse_sig(const void *data, size_t *len, size_t *sig_len, const char *name); > > > > #endif /* _LINUX_MODULE_SIGNATURE_H */ > > diff --git a/kernel/module_signature.c b/kernel/module_signature.c > > index 00132d12487c..784b40575ee4 100644 > > --- a/kernel/module_signature.c > > +++ b/kernel/module_signature.c > > @@ -8,14 +8,36 @@ > > > > #include > > #include > > +#include > > #include > > #include > > > > +/** > > + * mod_check_sig_marker - check that the given data has signature marker at the end > > + * > > + * @data: Data with appended signature > > + * @len: Length of data. Signature marker length is subtracted on success. > > + */ > > +static inline int mod_check_sig_marker(const void *data, size_t *len) > > I personally don't like it when a function has a "check" in it's name > as it doesn't describe what the function is checking for. For me It is consistent with mod_check_sig > mod_has_sig_marker is much more precise. I would use that instead. It actually would not because it does more than that. Thanks Michal > > Thanks > Philipp > > > +{ > > + const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1; > > + > > + if (markerlen > *len) > > + return -ENODATA; > > + > > + if (memcmp(data + *len - markerlen, MODULE_SIG_STRING, > > + markerlen)) > > + return -ENODATA; > > + > > + *len -= markerlen; > > + return 0; > > +} > > + > > /** > > * mod_check_sig - check that the given signature is sane > > * > > * @ms: Signature to check. > > - * @file_len: Size of the file to which @ms is appended. > > + * @file_len: Size of the file to which @ms is appended (without the marker). > > * @name: What is being checked. Used for error messages. > > */ > > int mod_check_sig(const struct module_signature *ms, size_t file_len, > > @@ -44,3 +66,35 @@ int mod_check_sig(const struct module_signature *ms, size_t file_len, > > > > return 0; > > } > > + > > +/** > > + * mod_parse_sig - check that the given signature is sane and determine signature length > > + * > > + * @data: Data with appended signature. > > + * @len: Length of data. Signature and marker length is subtracted on success. > > + * @sig_len: Length of signature. Filled on success. > > + * @name: What is being checked. Used for error messages. > > + */ > > +int mod_parse_sig(const void *data, size_t *len, size_t *sig_len, const char *name) > > +{ > > + const struct module_signature *sig; > > + int rc; > > + > > + rc = mod_check_sig_marker(data, len); > > + if (rc) > > + return rc; > > + > > + if (*len < sizeof(*sig)) > > + return -ENODATA; > > + > > + sig = (const struct module_signature *)(data + (*len - sizeof(*sig))); > > + > > + rc = mod_check_sig(sig, *len, name); > > + if (rc) > > + return rc; > > + > > + *sig_len = be32_to_cpu(sig->sig_len); > > + *len -= *sig_len + sizeof(*sig); > > + > > + return 0; > > +} > > diff --git a/kernel/module_signing.c b/kernel/module_signing.c > > index cef72a6f6b5d..02bbca90f467 100644 > > --- a/kernel/module_signing.c > > +++ b/kernel/module_signing.c > > @@ -25,35 +25,17 @@ int verify_appended_signature(const void *data, size_t *len, > > struct key *trusted_keys, > > enum key_being_used_for purpose) > > { > > - const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1; > > struct module_signature ms; > > - size_t sig_len, modlen = *len; > > + size_t sig_len; > > int ret; > > > > - pr_devel("==>%s %s(,%zu)\n", __func__, key_being_used_for[purpose], modlen); > > + pr_devel("==>%s %s(,%zu)\n", __func__, key_being_used_for[purpose], *len); > > > > - if (markerlen > modlen) > > - return -ENODATA; > > - > > - if (memcmp(data + modlen - markerlen, MODULE_SIG_STRING, > > - markerlen)) > > - return -ENODATA; > > - modlen -= markerlen; > > - > > - if (modlen <= sizeof(ms)) > > - return -EBADMSG; > > - > > - memcpy(&ms, data + (modlen - sizeof(ms)), sizeof(ms)); > > - > > - ret = mod_check_sig(&ms, modlen, key_being_used_for[purpose]); > > + ret = mod_parse_sig(data, len, &sig_len, key_being_used_for[purpose]); > > if (ret) > > return ret; > > > > - sig_len = be32_to_cpu(ms.sig_len); > > - modlen -= sig_len + sizeof(ms); > > - *len = modlen; > > - > > - return verify_pkcs7_signature(data, modlen, data + modlen, sig_len, > > + return verify_pkcs7_signature(data, *len, data + *len, sig_len, > > trusted_keys, > > purpose, > > NULL, NULL); > > diff --git a/security/integrity/ima/ima_modsig.c b/security/integrity/ima/ima_modsig.c > > index fb25723c65bc..46917eb37fd8 100644 > > --- a/security/integrity/ima/ima_modsig.c > > +++ b/security/integrity/ima/ima_modsig.c > > @@ -37,33 +37,17 @@ struct modsig { > > * > > * Return: 0 on success, error code otherwise. > > */ > > -int ima_read_modsig(enum ima_hooks func, const void *buf, loff_t buf_len, > > +int ima_read_modsig(enum ima_hooks func, const void *buf, loff_t len, > > struct modsig **modsig) > > { > > - const size_t marker_len = strlen(MODULE_SIG_STRING); > > - const struct module_signature *sig; > > struct modsig *hdr; > > - size_t sig_len; > > - const void *p; > > + size_t sig_len, buf_len = len; > > int rc; > > > > - if (buf_len <= marker_len + sizeof(*sig)) > > - return -ENOENT; > > - > > - p = buf + buf_len - marker_len; > > - if (memcmp(p, MODULE_SIG_STRING, marker_len)) > > - return -ENOENT; > > - > > - buf_len -= marker_len; > > - sig = (const struct module_signature *)(p - sizeof(*sig)); > > - > > - rc = mod_check_sig(sig, buf_len, func_tokens[func]); > > + rc = mod_parse_sig(buf, &buf_len, &sig_len, func_tokens[func]); > > if (rc) > > return rc; > > > > - sig_len = be32_to_cpu(sig->sig_len); > > - buf_len -= sig_len + sizeof(*sig); > > - > > /* Allocate sig_len additional bytes to hold the raw PKCS#7 data. */ > > hdr = kzalloc(sizeof(*hdr) + sig_len, GFP_KERNEL); > > if (!hdr) >