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Message-ID: <21bc4d6b-6c06-3bbb-f2f4-7d10d289c3a4@digikod.net>
Date: Mon, 12 Sep 2022 19:17:27 +0200
From: Mickaël Salaün <mic@...ikod.net>
To: "Konstantin Meskhidze (A)" <konstantin.meskhidze@...wei.com>
Cc: willemdebruijn.kernel@...il.com, gnoack3000@...il.com,
linux-security-module@...r.kernel.org, netdev@...r.kernel.org,
netfilter-devel@...r.kernel.org, anton.sirazetdinov@...wei.com
Subject: Re: [PATCH v7 03/18] landlock: refactor merge/inherit_ruleset
functions
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@...wei.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
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