Re: [PATCH v7 03/18] landlock: refactor merge/inherit_ruleset functions

["Mickaël Salaün" <mic@digikod.net>]

On 09/09/2022 16:53, Konstantin Meskhidze (A) wrote:
> 
> 
> 9/6/2022 11:07 AM, Mickaël Salaün пишет:
>>
>> On 29/08/2022 19:03, Konstantin Meskhidze wrote:
>>> Refactors merge_ruleset() and inherit_ruleset() functions to support
>>> new rule types. This patch adds merge_tree() and inherit_tree()
>>> helpers. Each has key_type argument to choose a particular rb_tree
>>> structure in a ruleset.
>>>
>>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
>>> ---
>>>
>>> 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 | 108 +++++++++++++++++++++++-------------
>>>    1 file changed, 69 insertions(+), 39 deletions(-)
>>>
>>> diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
>>> index 41de17d1869e..3a5ef356aaa3 100644
>>> --- a/security/landlock/ruleset.c
>>> +++ b/security/landlock/ruleset.c
>>> @@ -302,36 +302,18 @@ 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;
>>> -
>>> -	src_root = get_root(src, LANDLOCK_KEY_INODE);
>>
>> This hunk is a bit misleading, but please add a might_sleep() call here
>> because of the insert_rule() call, and some lock asserts:
>>
>> might_sleep();
>> lockdep_assert_held(&dst->lock);
>> lockdep_assert_held(&src->lock);
> 
>     it was moved into merge_ruleset() function,
>     please check below.

I know but you still need to add these asserts.


> 
>>
>>
>>> +	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) {
>>> @@ -340,7 +322,7 @@ 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))
>>> @@ -351,8 +333,39 @@ static int merge_ruleset(struct landlock_ruleset *const dst,
>>>
>>>    		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);
>>> @@ -360,43 +373,60 @@ 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;
>>> -
>>> -	parent_root = get_root(parent, LANDLOCK_KEY_INODE);
>>
>> This hunk is a bit misleading, but please add a might_sleep() call here
>> because of the insert_rule() call, and some lock asserts:
>>
>> might_sleep();
>> lockdep_assert_held(&parent->lock);
>> lockdep_assert_held(&child->lock);
>>
>     it was moved into inherit_ruleset() function,
>     please check below.

same