[PATCH] IMA: use list_splice_tail_init_rcu() instead of its open coded variant

[PATCH] IMA: use list_splice_tail_init_rcu() instead of its open coded variant

[Petko Manolov]

	Hi Mimi,

Please review and consider this patch for mainlining if it looks OK to you.  
I've tested it on v4.17.0-rc6 and seems to be working fine.


		Petko


---
>From e5cb36d4470cf64af2087fba4615ee8539385c98 Mon Sep 17 00:00:00 2001
From: Petko Manolov <petko.manolov@konsulko.com>
Date: Fri, 18 May 2018 14:10:57 +0300
Subject: [PATCH] Replace the open coded version with
 list_splice_tail_init_rcu()

Signed-off-by: Petko Manolov <petko.manolov@konsulko.com>
---
 security/integrity/ima/ima_policy.c | 17 ++---------------
 1 file changed, 2 insertions(+), 15 deletions(-)

diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index d89bebf85421..722466f843ef 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -509,22 +509,9 @@ int ima_check_policy(void)
  */
 void ima_update_policy(void)
 {
-	struct list_head *first, *last, *policy;
+	struct list_head *policy = &ima_policy_rules;
 
-	/* append current policy with the new rules */
-	first = (&ima_temp_rules)->next;
-	last = (&ima_temp_rules)->prev;
-	policy = &ima_policy_rules;
-
-	synchronize_rcu();
-
-	last->next = policy;
-	rcu_assign_pointer(list_next_rcu(policy->prev), first);
-	first->prev = policy->prev;
-	policy->prev = last;
-
-	/* prepare for the next policy rules addition */
-	INIT_LIST_HEAD(&ima_temp_rules);
+	list_splice_tail_init_rcu(&ima_temp_rules, policy, synchronize_rcu);
 
 	if (ima_rules != policy) {
 		ima_policy_flag = 0;
-- 
2.11.0

Re: [PATCH] IMA: use list_splice_tail_init_rcu() instead of its open coded variant

[Mimi Zohar]

Hi Petko,

On Tue, 2018-05-22 at 17:06 +0300, Petko Manolov wrote:

The patch description is missing.  Is the following ok?

Use list_splice_tail_init_rcu() to extend the existing custom IMA
policy with additional IMA policy rules.

Mimi

> 
> Signed-off-by: Petko Manolov <petko.manolov@konsulko.com>
> ---
>  security/integrity/ima/ima_policy.c | 17 ++---------------
>  1 file changed, 2 insertions(+), 15 deletions(-)
> 
> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> index d89bebf85421..722466f843ef 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -509,22 +509,9 @@ int ima_check_policy(void)
>   */
>  void ima_update_policy(void)
>  {
> -	struct list_head *first, *last, *policy;
> +	struct list_head *policy = &ima_policy_rules;
> 
> -	/* append current policy with the new rules */
> -	first = (&ima_temp_rules)->next;
> -	last = (&ima_temp_rules)->prev;
> -	policy = &ima_policy_rules;
> -
> -	synchronize_rcu();
> -
> -	last->next = policy;
> -	rcu_assign_pointer(list_next_rcu(policy->prev), first);
> -	first->prev = policy->prev;
> -	policy->prev = last;
> -
> -	/* prepare for the next policy rules addition */
> -	INIT_LIST_HEAD(&ima_temp_rules);
> +	list_splice_tail_init_rcu(&ima_temp_rules, policy, synchronize_rcu);
> 
>  	if (ima_rules != policy) {
>  		ima_policy_flag = 0;