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Date: Fri, 9 Sep 2022 17:53:48 +0300
From: "Konstantin Meskhidze (A)" <konstantin.meskhidze@...wei.com>
To: Mickaël Salaün <mic@...ikod.net>
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
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.
>
>
>> + 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.
>
>> + 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
>>
> .
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