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Date: Tue, 6 Sep 2022 10:07:20 +0200
From: Mickaël Salaün <mic@...ikod.net>
To: Konstantin Meskhidze <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, yusongping@...wei.com,
hukeping@...wei.com, anton.sirazetdinov@...wei.com
Subject: Re: [PATCH v7 03/18] landlock: refactor merge/inherit_ruleset
functions
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);
> + 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);
> + 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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