From patchwork Wed Nov 11 21:34:38 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= X-Patchwork-Id: 11898585 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id AED9A16C0 for ; Wed, 11 Nov 2020 21:35:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 97D072151B for ; Wed, 11 Nov 2020 21:35:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727121AbgKKVfU (ORCPT ); Wed, 11 Nov 2020 16:35:20 -0500 Received: from smtp-42ae.mail.infomaniak.ch ([84.16.66.174]:50391 "EHLO smtp-42ae.mail.infomaniak.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727153AbgKKVew (ORCPT ); Wed, 11 Nov 2020 16:34:52 -0500 Received: from smtp-2-0000.mail.infomaniak.ch (unknown [10.5.36.107]) by smtp-3-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 4CWdL304KkzlhKmV; Wed, 11 Nov 2020 22:34:51 +0100 (CET) Received: from localhost (unknown [94.23.54.103]) by smtp-2-0000.mail.infomaniak.ch (Postfix) with ESMTPA id 4CWdL25R2dzlh8T9; Wed, 11 Nov 2020 22:34:50 +0100 (CET) From: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= To: James Morris , Jann Horn , "Serge E . Hallyn" Cc: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= , Shuah Khan , Vincent Dagonneau , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-security-module@vger.kernel.org Subject: [PATCH v1 5/9] landlock: Add extra checks when inserting a rule Date: Wed, 11 Nov 2020 22:34:38 +0100 Message-Id: <20201111213442.434639-6-mic@digikod.net> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201111213442.434639-1-mic@digikod.net> References: <20201111213442.434639-1-mic@digikod.net> MIME-Version: 1.0 Precedence: bulk List-ID: Make sure that there is always an (allocated) object in each used rules. This could have prevented the bug fixed with a previous commit. When the rules from a ruleset are merged in a domain with landlock_enforce_ruleset_current(2), these new rules should be assigned to the last layer. However, when a rule is just extending a ruleset with landlock_add_rule(2), the number of layers of this updated ruleset should always be 0. Checking such use of landlock_insert_rule() could enable to detect bugs in future developments. Replace the hardcoded 1 with SINGLE_DEPTH_NESTING. Cc: James Morris Cc: Jann Horn Cc: Serge E. Hallyn Signed-off-by: Mickaël Salaün --- security/landlock/ruleset.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c index 7654a66cea43..1fb85daeb750 100644 --- a/security/landlock/ruleset.c +++ b/security/landlock/ruleset.c @@ -102,6 +102,10 @@ int landlock_insert_rule(struct landlock_ruleset *const ruleset, might_sleep(); lockdep_assert_held(&ruleset->lock); + if (WARN_ON_ONCE(!rule->object)) + return -ENOENT; + if (!is_merge && WARN_ON_ONCE(ruleset->nb_layers != 0)) + return -EINVAL; walker_node = &(ruleset->root.rb_node); while (*walker_node) { struct landlock_rule *const this = rb_entry(*walker_node, @@ -223,12 +227,7 @@ static struct landlock_ruleset *inherit_ruleset( return new_ruleset; mutex_lock(&new_ruleset->lock); - mutex_lock_nested(&parent->lock, 1); - new_ruleset->nb_layers = parent->nb_layers; - new_ruleset->fs_access_mask = parent->fs_access_mask; - WARN_ON_ONCE(!parent->hierarchy); - get_hierarchy(parent->hierarchy); - new_ruleset->hierarchy->parent = parent->hierarchy; + mutex_lock_nested(&parent->lock, SINGLE_DEPTH_NESTING); /* Copies the @parent tree. */ rbtree_postorder_for_each_entry_safe(walker_rule, next_rule, @@ -237,6 +236,12 @@ static struct landlock_ruleset *inherit_ruleset( if (err) goto out_unlock; } + new_ruleset->nb_layers = parent->nb_layers; + new_ruleset->fs_access_mask = parent->fs_access_mask; + WARN_ON_ONCE(!parent->hierarchy); + get_hierarchy(parent->hierarchy); + new_ruleset->hierarchy->parent = parent->hierarchy; + mutex_unlock(&parent->lock); mutex_unlock(&new_ruleset->lock); return new_ruleset;