[WIP][RFC][PATCH 1/3] security: introduce call_int_hook_and() macro

[Casey Schaufler]

On 8/18/2019 4:57 PM, Roberto Sassu wrote:
> The LSM hooks audit_rule_known() and audit_rule_match() define 1 as
> result for successful operation. However, the security_ functions use
> call_int_hook() which stops iterating over LSMs if the result is not
> zero.
>
> Introduce call_int_hook_and(), so that the final result returned by the
> security_ functions is 1 if all LSMs return 1.

I don't think this is what you want. You want an audit record
generated if any of the security modules want one, not only if
all of the security modules want one.

>
> Signed-off-by: Roberto Sassu <roberto.sassu at huawei.com>
> ---
>  security/security.c | 19 +++++++++++++++++--
>  1 file changed, 17 insertions(+), 2 deletions(-)
>
> diff --git a/security/security.c b/security/security.c
> index cbee0b7915d5..ff1736ee3410 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -634,6 +634,20 @@ static void __init lsm_early_task(struct task_struct *task)
>  	RC;							\
>  })
>  
> +#define call_int_hook_and(FUNC, IRC, ...) ({			\
> +	int RC = IRC;						\
> +	do {							\
> +		struct security_hook_list *P;			\
> +								\
> +		hlist_for_each_entry(P, &security_hook_heads.FUNC, list) { \
> +			RC = P->hook.FUNC(__VA_ARGS__);		\
> +			if (!RC)				\
> +				break;				\
> +		}						\
> +	} while (0);						\
> +	RC;							\
> +})
> +
>  /* Security operations */
>  
>  int security_binder_set_context_mgr(struct task_struct *mgr)
> @@ -2339,7 +2353,7 @@ int security_audit_rule_init(u32 field, u32 op, char *rulestr, void **lsmrule)
>  
>  int security_audit_rule_known(struct audit_krule *krule)
>  {
> -	return call_int_hook(audit_rule_known, 0, krule);
> +	return call_int_hook_and(audit_rule_known, 0, krule);
>  }
>  
>  void security_audit_rule_free(void *lsmrule)
> @@ -2349,7 +2363,8 @@ void security_audit_rule_free(void *lsmrule)
>  
>  int security_audit_rule_match(u32 secid, u32 field, u32 op, void *lsmrule)
>  {
> -	return call_int_hook(audit_rule_match, 0, secid, field, op, lsmrule);
> +	return call_int_hook_and(audit_rule_match, 0, secid, field, op,
> +				 lsmrule);
>  }
>  #endif /* CONFIG_AUDIT */
>