[PATCH bpf-next v10 5/5] bpf: Only enable BPF LSM hooks when an LSM program is attached

[KP Singh]

> On 9 May 2024, at 16:24, Paul Moore <paul at paul-moore.com> wrote:
> 
> On Wed, May 8, 2024 at 3:00 AM KP Singh <kpsingh at kernel.org> wrote:
>> One idea here is that only LSM hooks with default_state = false can be toggled.
>> 
>> This would also any ROPs that try to abuse this function. Maybe we can call "default_disabled" .toggleable (or dynamic)
>> 
>> and change the corresponding LSM_INIT_TOGGLEABLE. Kees, Paul, this may be a fair middle ground?
> 
> Seems reasonable to me, although I think it's worth respinning to get
> a proper look at it in context.  Some naming bikeshedding below ...
> 
>> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
>> index 4bd1d47bb9dc..5c0918ed6b80 100644
>> --- a/include/linux/lsm_hooks.h
>> +++ b/include/linux/lsm_hooks.h
>> @@ -117,7 +117,7 @@ struct security_hook_list {
>>        struct lsm_static_call  *scalls;
>>        union security_list_options     hook;
>>        const struct lsm_id             *lsmid;
>> -       bool                            default_enabled;
>> +       bool                            toggleable;
>> } __randomize_layout;
> 
> How about inverting the boolean and using something like 'fixed'
> instead of 'toggleable'?
> 

I would prefer not changing the all the other LSM_HOOK_INIT calls as we change the default behaviour then. How about calling it "dynamic" 

LSM_HOOK_INIT_DYNAMIC and call the boolean dynamic

- KP

> -- 
> paul-moore.com