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;