Re: [PATCH v10 05/13] landlock: Refactor merge/inherit_ruleset functions

["Konstantin Meskhidze (A)" <konstantin.meskhidze@huawei.com>]

4/16/2023 7:09 PM, Mickaël Salaün пишет:
> 
> On 23/03/2023 09:52, Konstantin Meskhidze wrote:
>> Refactor merge_ruleset() and inherit_ruleset() functions to support
>> new rule types. This patch adds merge_tree() and inherit_tree()
>> helpers. They use a specific ruleset's red-black tree according to
>> a key type argument.
>> 
>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
>> ---
>> 
>> Changes since v9:
>> * None
>> 
>> Changes since v8:
>> * Refactors commit message.
>> * Minor fixes.
>> 
>> Changes since v7:
>> * Adds missed lockdep_assert_held it inherit_tree() and merge_tree().
>> * Fixes comment.
>> 
>> Changes since v6:
>> * Refactors merge_ruleset() and inherit_ruleset() functions to support
>>    new rule types.
>> * Renames tree_merge() to merge_tree() (and reorder arguments), and
>>    tree_copy() to inherit_tree().
>> 
>> Changes since v5:
>> * Refactors some logic errors.
>> * Formats code with clang-format-14.
>> 
>> Changes since v4:
>> * None
>> 
>> ---
>>   security/landlock/ruleset.c | 110 ++++++++++++++++++++++++------------
>>   1 file changed, 73 insertions(+), 37 deletions(-)
>> 
>> diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
>> index d3859d5e7306..2579c9bbedbc 100644
>> --- a/security/landlock/ruleset.c
>> +++ b/security/landlock/ruleset.c
>> @@ -302,36 +302,22 @@ static void put_hierarchy(struct landlock_hierarchy *hierarchy)
>>   	}
>>   }
>> 
>> -static int merge_ruleset(struct landlock_ruleset *const dst,
>> -			 struct landlock_ruleset *const src)
>> +static int merge_tree(struct landlock_ruleset *const dst,
>> +		      struct landlock_ruleset *const src,
>> +		      const enum landlock_key_type key_type)
>>   {
>>   	struct landlock_rule *walker_rule, *next_rule;
>>   	struct rb_root *src_root;
>>   	int err = 0;
>> 
>>   	might_sleep();
>> -	/* Should already be checked by landlock_merge_ruleset() */
>> -	if (WARN_ON_ONCE(!src))
>> -		return 0;
>> -	/* Only merge into a domain. */
>> -	if (WARN_ON_ONCE(!dst || !dst->hierarchy))
>> -		return -EINVAL;
>> +	lockdep_assert_held(&dst->lock);
>> +	lockdep_assert_held(&src->lock);
>> 
>> -	src_root = get_root(src, LANDLOCK_KEY_INODE);
>> +	src_root = get_root(src, key_type);
>>   	if (IS_ERR(src_root))
>>   		return PTR_ERR(src_root);
>> 
>> -	/* Locks @dst first because we are its only owner. */
>> -	mutex_lock(&dst->lock);
>> -	mutex_lock_nested(&src->lock, SINGLE_DEPTH_NESTING);
>> -
>> -	/* Stacks the new layer. */
>> -	if (WARN_ON_ONCE(src->num_layers != 1 || dst->num_layers < 1)) {
>> -		err = -EINVAL;
>> -		goto out_unlock;
>> -	}
>> -	dst->access_masks[dst->num_layers - 1] = src->access_masks[0];
>> -
>>   	/* Merges the @src tree. */
>>   	rbtree_postorder_for_each_entry_safe(walker_rule, next_rule, src_root,
>>   					     node) {
>> @@ -340,23 +326,52 @@ static int merge_ruleset(struct landlock_ruleset *const dst,
>>   		} };
>>   		const struct landlock_id id = {
>>   			.key = walker_rule->key,
>> -			.type = LANDLOCK_KEY_INODE,
>> +			.type = key_type,
>>   		};
>> 
>>   		if (WARN_ON_ONCE(walker_rule->num_layers != 1)) {
>>   			err = -EINVAL;
>> -			goto out_unlock;
> 
> This should be replaced with `return -EINVAL;` and the `{` `}` after the
> if condition are not needed anymore.
> 
   Ok. Will be changed.
> 
>>   		}
>>   		if (WARN_ON_ONCE(walker_rule->layers[0].level != 0)) {
>>   			err = -EINVAL;
>> -			goto out_unlock;
> 
> ditto

   Got it.
> 
>>   		}
>>   		layers[0].access = walker_rule->layers[0].access;
>> 
>>   		err = insert_rule(dst, id, &layers, ARRAY_SIZE(layers));
>>   		if (err)
>> -			goto out_unlock;
>> +			return err;
>> +	}
>> +	return err;
>> +}
>> +
>> +static int merge_ruleset(struct landlock_ruleset *const dst,
>> +			 struct landlock_ruleset *const src)
>> +{
>> +	int err = 0;
>> +
>> +	might_sleep();
>> +	/* Should already be checked by landlock_merge_ruleset() */
>> +	if (WARN_ON_ONCE(!src))
>> +		return 0;
>> +	/* Only merge into a domain. */
>> +	if (WARN_ON_ONCE(!dst || !dst->hierarchy))
>> +		return -EINVAL;
>> +
>> +	/* Locks @dst first because we are its only owner. */
>> +	mutex_lock(&dst->lock);
>> +	mutex_lock_nested(&src->lock, SINGLE_DEPTH_NESTING);
>> +
>> +	/* Stacks the new layer. */
>> +	if (WARN_ON_ONCE(src->num_layers != 1 || dst->num_layers < 1)) {
>> +		err = -EINVAL;
>> +		goto out_unlock;
>>   	}
>> +	dst->access_masks[dst->num_layers - 1] = src->access_masks[0];
>> +
>> +	/* Merges the @src inode tree. */
>> +	err = merge_tree(dst, src, LANDLOCK_KEY_INODE);
>> +	if (err)
>> +		goto out_unlock;
>> 
>>   out_unlock:
>>   	mutex_unlock(&src->lock);
>> @@ -364,43 +379,64 @@ static int merge_ruleset(struct landlock_ruleset *const dst,
>>   	return err;
>>   }
>> 
>> -static int inherit_ruleset(struct landlock_ruleset *const parent,
>> -			   struct landlock_ruleset *const child)
>> +static int inherit_tree(struct landlock_ruleset *const parent,
>> +			struct landlock_ruleset *const child,
>> +			const enum landlock_key_type key_type)
>>   {
>>   	struct landlock_rule *walker_rule, *next_rule;
>>   	struct rb_root *parent_root;
>>   	int err = 0;
>> 
>>   	might_sleep();
>> -	if (!parent)
>> -		return 0;
>> +	lockdep_assert_held(&parent->lock);
>> +	lockdep_assert_held(&child->lock);
>> 
>> -	parent_root = get_root(parent, LANDLOCK_KEY_INODE);
>> +	parent_root = get_root(parent, key_type);
>>   	if (IS_ERR(parent_root))
>>   		return PTR_ERR(parent_root);
>> 
>> -	/* Locks @child first because we are its only owner. */
>> -	mutex_lock(&child->lock);
>> -	mutex_lock_nested(&parent->lock, SINGLE_DEPTH_NESTING);
>> -
>> -	/* Copies the @parent tree. */
>> +	/* Copies the @parent inode or network tree. */
>>   	rbtree_postorder_for_each_entry_safe(walker_rule, next_rule,
>>   					     parent_root, node) {
>>   		const struct landlock_id id = {
>>   			.key = walker_rule->key,
>> -			.type = LANDLOCK_KEY_INODE,
>> +			.type = key_type,
>>   		};
>> +
>>   		err = insert_rule(child, id, &walker_rule->layers,
>>   				  walker_rule->num_layers);
>>   		if (err)
>> -			goto out_unlock;
>> +			return err;
>>   	}
>> +	return err;
>> +}
>> +
>> +static int inherit_ruleset(struct landlock_ruleset *const parent,
>> +			   struct landlock_ruleset *const child)
>> +{
>> +	int err = 0;
>> +
>> +	might_sleep();
>> +	if (!parent)
>> +		return 0;
>> +
>> +	/* Locks @child first because we are its only owner. */
>> +	mutex_lock(&child->lock);
>> +	mutex_lock_nested(&parent->lock, SINGLE_DEPTH_NESTING);
>> +
>> +	/* Copies the @parent inode tree. */
>> +	err = inherit_tree(parent, child, LANDLOCK_KEY_INODE);
>> +	if (err)
>> +		goto out_unlock;
>> 
>>   	if (WARN_ON_ONCE(child->num_layers <= parent->num_layers)) {
>>   		err = -EINVAL;
>>   		goto out_unlock;
>>   	}
>> -	/* Copies the parent layer stack and leaves a space for the new layer. */
>> +	/*
>> +	 * Copies the parent layer stack and leaves a space
>> +	 * for the new layer.
>> +	 */
>>   	memcpy(child->access_masks, parent->access_masks,
>>   	       flex_array_size(parent, access_masks, parent->num_layers));
>> 
>> --
>> 2.25.1
>> 
> .