From patchwork Wed Jan 13 13:40:13 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 362266 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 441EEC43381 for ; Wed, 13 Jan 2021 13:42:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E3CDB233FB for ; Wed, 13 Jan 2021 13:42:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725747AbhAMNmG (ORCPT ); Wed, 13 Jan 2021 08:42:06 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:52982 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726935AbhAMNmF (ORCPT ); Wed, 13 Jan 2021 08:42:05 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1610545238; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=wREJNFq1amBAl6HRWgMB0MKqw+u/sJVwXhEPRKqsHag=; b=CuTKLPpRhPovHuZ6ea8rfEMwfkGJm0Rg3bFtFphZY0V/S0F9JVnR29WuEB6PJgTjp6dqJG xoMD03yDEIIjo+gqZB1qhfROfmnnRhNaMPjA0X37TfYskBOoFY4ClEcCa48fqM1KJ5LDip VIUhcOa+M76ZNr7eetxuz0VL/EoA7bY= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-568-cfXE2W1nP52Qzxije5XCPQ-1; Wed, 13 Jan 2021 08:40:34 -0500 X-MC-Unique: cfXE2W1nP52Qzxije5XCPQ-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 7484A85EE8C; Wed, 13 Jan 2021 13:40:16 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-112-8.rdu2.redhat.com [10.10.112.8]) by smtp.corp.redhat.com (Postfix) with ESMTP id 878315D6A8; Wed, 13 Jan 2021 13:40:14 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells To: torvalds@linux-foundation.org cc: dhowells@redhat.com, jarkko@kernel.org, eric.snowberg@oracle.com, ard.biesheuvel@linaro.org, keyrings@vger.kernel.org, linux-crypto@vger.kernel.org, linux-security-module@vger.kernel.org, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] certs: Add EFI_CERT_X509_GUID support for dbx entries MIME-Version: 1.0 Content-ID: <2660555.1610545213.1@warthog.procyon.org.uk> Date: Wed, 13 Jan 2021 13:40:13 +0000 Message-ID: <2660556.1610545213@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org Hi Linus, Are you willing to take this between merge windows - or does it need to wait for the next merge window? It's not technically a bug fix to the kernel, but it does have a CVE attached to it. Note that I've also updated Jarkko's address in his Reviewed-by since his Intel address no longer works. David --- commit b5f71d4461d6d09463b2ce8bc4fc150ea1c385c0 Author: Eric Snowberg Date: Tue Sep 15 20:49:27 2020 -0400 certs: Add EFI_CERT_X509_GUID support for dbx entries This fixes CVE-2020-26541. The Secure Boot Forbidden Signature Database, dbx, contains a list of now revoked signatures and keys previously approved to boot with UEFI Secure Boot enabled. The dbx is capable of containing any number of EFI_CERT_X509_SHA256_GUID, EFI_CERT_SHA256_GUID, and EFI_CERT_X509_GUID entries. Currently when EFI_CERT_X509_GUID are contained in the dbx, the entries are skipped. Add support for EFI_CERT_X509_GUID dbx entries. When a EFI_CERT_X509_GUID is found, it is added as an asymmetrical key to the .blacklist keyring. Anytime the .platform keyring is used, the keys in the .blacklist keyring are referenced, if a matching key is found, the key will be rejected. [DH: I've changed the names of the new functions with Eric's approval] Signed-off-by: Eric Snowberg Reviewed-by: Jarkko Sakkinen Signed-off-by: David Howells diff --git a/certs/blacklist.c b/certs/blacklist.c index 6514f9ebc943..a7f021878a4b 100644 --- a/certs/blacklist.c +++ b/certs/blacklist.c @@ -100,6 +100,38 @@ int mark_hash_blacklisted(const char *hash) return 0; } +int add_key_to_revocation_list(const char *data, size_t size) +{ + key_ref_t key; + + key = key_create_or_update(make_key_ref(blacklist_keyring, true), + "asymmetric", + NULL, + data, + size, + ((KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW), + KEY_ALLOC_NOT_IN_QUOTA | KEY_ALLOC_BUILT_IN); + + if (IS_ERR(key)) { + pr_err("Problem with revocation key (%ld)\n", PTR_ERR(key)); + return PTR_ERR(key); + } + + return 0; +} + +int is_key_on_revocation_list(struct pkcs7_message *pkcs7) +{ + int ret; + + ret = validate_trust(pkcs7, blacklist_keyring); + + if (ret == 0) + return -EKEYREJECTED; + + return -ENOKEY; +} + /** * is_hash_blacklisted - Determine if a hash is blacklisted * @hash: The hash to be checked as a binary blob diff --git a/certs/blacklist.h b/certs/blacklist.h index 1efd6fa0dc60..420bb7c86e07 100644 --- a/certs/blacklist.h +++ b/certs/blacklist.h @@ -1,3 +1,15 @@ #include +#include +#include extern const char __initconst *const blacklist_hashes[]; + +#ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING +#define validate_trust pkcs7_validate_trust +#else +static inline int validate_trust(struct pkcs7_message *pkcs7, + struct key *trust_keyring) +{ + return -ENOKEY; +} +#endif diff --git a/certs/system_keyring.c b/certs/system_keyring.c index 798291177186..cc165b359ea3 100644 --- a/certs/system_keyring.c +++ b/certs/system_keyring.c @@ -241,6 +241,12 @@ int verify_pkcs7_message_sig(const void *data, size_t len, pr_devel("PKCS#7 platform keyring is not available\n"); goto error; } + + ret = is_key_on_revocation_list(pkcs7); + if (ret != -ENOKEY) { + pr_devel("PKCS#7 platform key is on revocation list\n"); + goto error; + } } ret = pkcs7_validate_trust(pkcs7, trusted_keys); if (ret < 0) { diff --git a/include/keys/system_keyring.h b/include/keys/system_keyring.h index fb8b07daa9d1..61f98739e8b1 100644 --- a/include/keys/system_keyring.h +++ b/include/keys/system_keyring.h @@ -31,11 +31,14 @@ extern int restrict_link_by_builtin_and_secondary_trusted( #define restrict_link_by_builtin_and_secondary_trusted restrict_link_by_builtin_trusted #endif +extern struct pkcs7_message *pkcs7; #ifdef CONFIG_SYSTEM_BLACKLIST_KEYRING extern int mark_hash_blacklisted(const char *hash); +extern int add_key_to_revocation_list(const char *data, size_t size); extern int is_hash_blacklisted(const u8 *hash, size_t hash_len, const char *type); extern int is_binary_blacklisted(const u8 *hash, size_t hash_len); +extern int is_key_on_revocation_list(struct pkcs7_message *pkcs7); #else static inline int is_hash_blacklisted(const u8 *hash, size_t hash_len, const char *type) @@ -47,6 +50,14 @@ static inline int is_binary_blacklisted(const u8 *hash, size_t hash_len) { return 0; } +static inline int add_key_to_revocation_list(const char *data, size_t size) +{ + return 0; +} +static inline int is_key_on_revocation_list(struct pkcs7_message *pkcs7) +{ + return -ENOKEY; +} #endif #ifdef CONFIG_IMA_BLACKLIST_KEYRING diff --git a/security/integrity/platform_certs/keyring_handler.c b/security/integrity/platform_certs/keyring_handler.c index c5ba695c10e3..5604bd57c990 100644 --- a/security/integrity/platform_certs/keyring_handler.c +++ b/security/integrity/platform_certs/keyring_handler.c @@ -55,6 +55,15 @@ static __init void uefi_blacklist_binary(const char *source, uefi_blacklist_hash(source, data, len, "bin:", 4); } +/* + * Add an X509 cert to the revocation list. + */ +static __init void uefi_revocation_list_x509(const char *source, + const void *data, size_t len) +{ + add_key_to_revocation_list(data, len); +} + /* * Return the appropriate handler for particular signature list types found in * the UEFI db and MokListRT tables. @@ -76,5 +85,7 @@ __init efi_element_handler_t get_handler_for_dbx(const efi_guid_t *sig_type) return uefi_blacklist_x509_tbs; if (efi_guidcmp(*sig_type, efi_cert_sha256_guid) == 0) return uefi_blacklist_binary; + if (efi_guidcmp(*sig_type, efi_cert_x509_guid) == 0) + return uefi_revocation_list_x509; return 0; }