From patchwork Mon Jan 10 13:49:58 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: =?utf-8?q?Michal_Such=C3=A1nek?= X-Patchwork-Id: 12708825 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 8B38FC43219 for ; Mon, 10 Jan 2022 13:50:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234574AbiAJNuO (ORCPT ); Mon, 10 Jan 2022 08:50:14 -0500 Received: from smtp-out1.suse.de ([195.135.220.28]:36744 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233954AbiAJNuK (ORCPT ); Mon, 10 Jan 2022 08:50:10 -0500 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id 0DC7D212BB; Mon, 10 Jan 2022 13:50:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1641822608; 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=y8UfsVs9ewQVYRAbN7Ug1IzhKfCrKnLEWfDZ94pDZQ8=; b=mKenB4Clw5CYe+TAg15IUaDmLkwbLOVkUcU8tymww/MniKePlDSYxOY4aDwwfdbHke7Bgw DWtBIuf/zidfvBtVfPMkZOO+XHaRnWdMWYwyoXPNS+FoDyy0aKTz2zKX1F0KVCtAIdXK8K SNJVdWvN0kn9xPKJP/tQDfZsjx8dBS8= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1641822608; 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=y8UfsVs9ewQVYRAbN7Ug1IzhKfCrKnLEWfDZ94pDZQ8=; b=tHBKSy4UOfGBis4IGWS254lpdyHkmiPEhyj48Ig1bycfLuI0amwmH5IgzM1xlooypS3zng LK+y4Yd+6fGmSNDA== Received: from kitsune.suse.cz (kitsune.suse.cz [10.100.12.127]) by relay2.suse.de (Postfix) with ESMTP id BB06EA3B8D; Mon, 10 Jan 2022 13:50:07 +0000 (UTC) From: Michal Suchanek To: keyrings@vger.kernel.org, linux-crypto@vger.kernel.org, linux-integrity@vger.kernel.org Cc: Michal Suchanek , kexec@lists.infradead.org, Philipp Rudo , 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-security-module@vger.kernel.org Subject: [PATCH v4 6/6] module: Move duplicate mod_check_sig users code to mod_parse_sig Date: Mon, 10 Jan 2022 14:49:58 +0100 Message-Id: <59d134a3eae4fa802ed9135385cee6fe4838ec01.1641822505.git.msuchanek@suse.de> X-Mailer: git-send-email 2.31.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: 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. This changes the error from ENOENT to ENODATA for ima_read_modsig in the case the signature marker is missing. This also changes the buffer length in ima_read_modsig from size_t to unsigned long. This reduces the possible value range on 32bit but the length refers to kernel in-memory buffer which cannot be longer than ULONG_MAX. Signed-off-by: Michal Suchanek --- v3: - Philipp Rudo : Update the commit with note about change of raturn value - Preserve the EBADMSG error code while moving code araound v4: - remove unused variable ms in module_signing - note about buffer length --- include/linux/module_signature.h | 1 + kernel/module_signature.c | 56 ++++++++++++++++++++++++++++- kernel/module_signing.c | 27 +++----------- security/integrity/ima/ima_modsig.c | 22 ++---------- 4 files changed, 63 insertions(+), 43 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..b8eb30182183 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) +{ + 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 -EBADMSG; + + 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 20857d2a15ca..1d4cb03cce21 100644 --- a/kernel/module_signing.c +++ b/kernel/module_signing.c @@ -25,35 +25,16 @@ int verify_appended_signature(const void *data, unsigned long *len, struct key *trusted_keys, enum key_being_used_for purpose) { - const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1; - struct module_signature *ms; - unsigned long sig_len, modlen = *len; + unsigned long sig_len; int ret; - pr_devel("==>%s %s(,%lu)\n", __func__, key_being_used_for[purpose], modlen); + pr_devel("==>%s %s(,%lu)\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; - - ms = data + modlen - 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..b40c8fdf6139 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; + unsigned long 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)