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 X-Spam-Level: X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00, 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 B8578C433DB for ; Wed, 20 Jan 2021 12:40:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8076922A84 for ; Wed, 20 Jan 2021 12:40:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732308AbhATMkF (ORCPT ); Wed, 20 Jan 2021 07:40:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39532 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389054AbhATLQC (ORCPT ); Wed, 20 Jan 2021 06:16:02 -0500 Received: from smtp-bc08.mail.infomaniak.ch (smtp-bc08.mail.infomaniak.ch [IPv6:2001:1600:4:17::bc08]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2F9C7C0613ED for ; Wed, 20 Jan 2021 03:15:14 -0800 (PST) Received: from smtp-3-0000.mail.infomaniak.ch (unknown [10.4.36.107]) by smtp-3-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 4DLNGm2v28zMqQD9; Wed, 20 Jan 2021 12:15:12 +0100 (CET) Received: from ns3096276.ip-94-23-54.eu (unknown [23.97.221.149]) by smtp-3-0000.mail.infomaniak.ch (Postfix) with ESMTPA id 4DLNGl3psPzlh8TX; Wed, 20 Jan 2021 12:15:11 +0100 (CET) Subject: Re: [PATCH v3 04/10] certs: Fix blacklist flag type confusion To: Jarkko Sakkinen Cc: David Howells , David Woodhouse , "David S . Miller" , Herbert Xu , James Morris , =?UTF-8?Q?Micka=c3=abl_Sala=c3=bcn?= , Mimi Zohar , "Serge E . Hallyn" , keyrings@vger.kernel.org, linux-crypto@vger.kernel.org, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, Mimi Zohar References: <20210114151909.2344974-1-mic@digikod.net> <20210114151909.2344974-5-mic@digikod.net> From: =?UTF-8?Q?Micka=c3=abl_Sala=c3=bcn?= Message-ID: Date: Wed, 20 Jan 2021 12:15:10 +0100 User-Agent: MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=iso-8859-15 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: keyrings@vger.kernel.org On 20/01/2021 04:55, Jarkko Sakkinen wrote: > On Thu, Jan 14, 2021 at 04:19:03PM +0100, Mickaël Salaün wrote: >> From: David Howells >> >> KEY_FLAG_KEEP is not meant to be passed to keyring_alloc() or key_alloc(), >> as these only take KEY_ALLOC_* flags. KEY_FLAG_KEEP has the same value as >> KEY_ALLOC_BYPASS_RESTRICTION, but fortunately only key_create_or_update() >> uses it. LSMs using the key_alloc hook don't check that flag. >> >> KEY_FLAG_KEEP is then ignored but fortunately (again) the root user cannot >> write to the blacklist keyring, so it is not possible to remove a key/hash >> from it. >> >> Fix this by adding a KEY_ALLOC_SET_KEEP flag that tells key_alloc() to set >> KEY_FLAG_KEEP on the new key. blacklist_init() can then, correctly, pass >> this to keyring_alloc(). > > OK, so thing work by luck now, but given the new patches which allow > to append new keys they would break, right? Without this fix, patch 9/10 would allow to remove and modify keys from the blacklist keyring. > >> We can also use this in ima_mok_init() rather than setting the flag >> manually. > > What does ima_mok_init() do? This was initially an addition from David Howells, I only fixed the argument bit-ORing. ima_mok_init() allocates a blacklist keyring (with different properties) dedicated to IMA. >> Note that this doesn't fix an observable bug with the current >> implementation but it is required to allow addition of new hashes to the >> blacklist in the future without making it possible for them to be removed. >> >> Fixes: 734114f8782f ("KEYS: Add a system blacklist keyring") >> cc: Mimi Zohar > > Nit: Cc OK > >> Cc: David Woodhouse >> Reported-by: Mickaël Salaün >> Signed-off-by: David Howells >> [mic@linux.microsoft.com: fix ima_mok_init()] >> Signed-off-by: Mickaël Salaün >> --- >> >> Changes since v2: >> * Cherry-pick rewritten v1 patch from >> https://lore.kernel.org/lkml/2659836.1607940186@warthog.procyon.org.uk/ >> to rebase on v5.11-rc3 and fix ima_mok_init(). >> --- >> certs/blacklist.c | 2 +- >> include/linux/key.h | 1 + >> security/integrity/ima/ima_mok.c | 4 +--- >> security/keys/key.c | 2 ++ >> 4 files changed, 5 insertions(+), 4 deletions(-) >> >> diff --git a/certs/blacklist.c b/certs/blacklist.c >> index a888b934a1cd..029471947838 100644 >> --- a/certs/blacklist.c >> +++ b/certs/blacklist.c >> @@ -162,7 +162,7 @@ static int __init blacklist_init(void) >> KEY_USR_VIEW | KEY_USR_READ | >> KEY_USR_SEARCH, >> KEY_ALLOC_NOT_IN_QUOTA | >> - KEY_FLAG_KEEP, >> + KEY_ALLOC_SET_KEEP, >> NULL, NULL); >> if (IS_ERR(blacklist_keyring)) >> panic("Can't allocate system blacklist keyring\n"); >> diff --git a/include/linux/key.h b/include/linux/key.h >> index 0f2e24f13c2b..eed3ce139a32 100644 >> --- a/include/linux/key.h >> +++ b/include/linux/key.h >> @@ -289,6 +289,7 @@ extern struct key *key_alloc(struct key_type *type, >> #define KEY_ALLOC_BUILT_IN 0x0004 /* Key is built into kernel */ >> #define KEY_ALLOC_BYPASS_RESTRICTION 0x0008 /* Override the check on restricted keyrings */ >> #define KEY_ALLOC_UID_KEYRING 0x0010 /* allocating a user or user session keyring */ >> +#define KEY_ALLOC_SET_KEEP 0x0020 /* Set the KEEP flag on the key/keyring */ >> >> extern void key_revoke(struct key *key); >> extern void key_invalidate(struct key *key); >> diff --git a/security/integrity/ima/ima_mok.c b/security/integrity/ima/ima_mok.c >> index 36cadadbfba4..5594dd38ab04 100644 >> --- a/security/integrity/ima/ima_mok.c >> +++ b/security/integrity/ima/ima_mok.c >> @@ -38,13 +38,11 @@ __init int ima_mok_init(void) >> (KEY_POS_ALL & ~KEY_POS_SETATTR) | >> KEY_USR_VIEW | KEY_USR_READ | >> KEY_USR_WRITE | KEY_USR_SEARCH, >> - KEY_ALLOC_NOT_IN_QUOTA, >> + KEY_ALLOC_NOT_IN_QUOTA | KEY_ALLOC_SET_KEEP, >> restriction, NULL); >> >> if (IS_ERR(ima_blacklist_keyring)) >> panic("Can't allocate IMA blacklist keyring."); >> - >> - set_bit(KEY_FLAG_KEEP, &ima_blacklist_keyring->flags); >> return 0; >> } >> device_initcall(ima_mok_init); >> diff --git a/security/keys/key.c b/security/keys/key.c >> index ebe752b137aa..c45afdd1dfbb 100644 >> --- a/security/keys/key.c >> +++ b/security/keys/key.c >> @@ -303,6 +303,8 @@ struct key *key_alloc(struct key_type *type, const char *desc, >> key->flags |= 1 << KEY_FLAG_BUILTIN; >> if (flags & KEY_ALLOC_UID_KEYRING) >> key->flags |= 1 << KEY_FLAG_UID_KEYRING; >> + if (flags & KEY_ALLOC_SET_KEEP) >> + key->flags |= 1 << KEY_FLAG_KEEP; >> >> #ifdef KEY_DEBUGGING >> key->magic = KEY_DEBUG_MAGIC; >> -- >> 2.30.0 >> > > Acked-by: Jarkko Sakkinen > > /Jarkko >