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From: "Mickaël Salaün" <mic@digikod.net>
To: James Morris <jmorris@namei.org>, Jann Horn <jannh@google.com>,
	"Serge E . Hallyn" <serge@hallyn.com>
Cc: "Mickaël Salaün" <mic@digikod.net>,
	"Shuah Khan" <shuah@kernel.org>,
	"Vincent Dagonneau" <vincent.dagonneau@ssi.gouv.fr>,
	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	[thread overview]
Message-ID: <20201111213442.434639-6-mic@digikod.net> (raw)
In-Reply-To: <20201111213442.434639-1-mic@digikod.net>

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 <jmorris@namei.org>
Cc: Jann Horn <jannh@google.com>
Cc: Serge E. Hallyn <serge@hallyn.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---
 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;
-- 
2.29.2


  parent reply	other threads:[~2020-11-11 21:35 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-11 21:34 [PATCH v1 0/9] Landlock fixes Mickaël Salaün
2020-11-11 21:34 ` [PATCH v1 1/9] landlock: Fix memory allocation error handling Mickaël Salaün
2020-11-11 21:34 ` [PATCH v1 2/9] landlock: Cosmetic fixes for filesystem management Mickaël Salaün
2020-11-20  1:37   ` James Morris
2020-11-11 21:34 ` [PATCH v1 3/9] landlock: Enforce deterministic interleaved path rules Mickaël Salaün
2020-11-11 21:34 ` [PATCH v1 4/9] landlock: Always intersect access rights Mickaël Salaün
2020-11-11 21:34 ` Mickaël Salaün [this message]
2020-11-11 21:34 ` [PATCH v1 6/9] selftests/landlock: Extend layout1.inherit_superset Mickaël Salaün
2020-11-11 21:34 ` [PATCH v1 7/9] landlock: Clean up get_ruleset_from_fd() Mickaël Salaün
2020-11-11 21:34 ` [PATCH v1 8/9] landlock: Add help to enable Landlock as a stacked LSM Mickaël Salaün
2020-11-11 21:34 ` [PATCH v1 9/9] landlock: Extend documentation about limitations Mickaël Salaün
2020-11-12  4:59 ` [PATCH v1 0/9] Landlock fixes James Morris

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