Re: [PATCH] lsm: drop LSM_ID_IMA

[Roberto Sassu <roberto.sassu@huaweicloud.com>]

On 10/23/2023 5:48 PM, Casey Schaufler wrote:
> On 10/23/2023 8:20 AM, Roberto Sassu wrote:
>> On 10/20/2023 11:56 PM, Casey Schaufler wrote:
>>> On 10/19/2023 1:08 AM, Roberto Sassu wrote:
>>>> On Wed, 2023-10-18 at 17:50 -0400, Paul Moore wrote:
>>>>> When IMA becomes a proper LSM we will reintroduce an appropriate
>>>>> LSM ID, but drop it from the userspace API for now in an effort
>>>>> to put an end to debates around the naming of the LSM ID macro.
>>>>>
>>>>> Signed-off-by: Paul Moore <paul@paul-moore.com>
>>>> Reviewed-by: Roberto Sassu <roberto.sassu@huawei.com>
>>>>
>>>> This makes sense according to the new goal of making 'ima' and 'evm' as
>>>> standalone LSMs.
>>>>
>>>> Otherwise, if we took existing LSMs, we should have defined
>>>> LSM_ID_INTEGRITY, associated to DEFINE_LSM(integrity).
>>>>
>>>> If we proceed with the new direction, I will add the new LSM IDs as
>>>> soon as IMA and EVM become LSMs.
>>>
>>> This seems right to me. Thank You.
>>
>> Perfect! Is it fine to assign an LSM ID to 'ima' and 'evm' and keep
>> the 'integrity' LSM to reserve space in the security blob without LSM
>> ID (as long as it does not register any hook)?
> 
> That will work, although it makes me wonder if all the data in the 'integrity' blob
> is used by both IMA and EVM. If these are going to be separate LSMs they should probably
> have their own security blobs. If there is data in common then an 'integrity' blob can
> still makes sense.

Yes, at the moment there is data in common, and we would need to check 
case-by-case. Would be good to do after moving IMA and EVM to the LSM 
infrastructure.

Roberto

>> Thanks
>>
>> Roberto
>>
>>>> Roberto
>>>>
>>>>> ---
>>>>>    include/uapi/linux/lsm.h | 15 +++++++--------
>>>>>    1 file changed, 7 insertions(+), 8 deletions(-)
>>>>>
>>>>> diff --git a/include/uapi/linux/lsm.h b/include/uapi/linux/lsm.h
>>>>> index eeda59a77c02..f0386880a78e 100644
>>>>> --- a/include/uapi/linux/lsm.h
>>>>> +++ b/include/uapi/linux/lsm.h
>>>>> @@ -54,14 +54,13 @@ struct lsm_ctx {
>>>>>    #define LSM_ID_SELINUX        101
>>>>>    #define LSM_ID_SMACK        102
>>>>>    #define LSM_ID_TOMOYO        103
>>>>> -#define LSM_ID_IMA        104
>>>>> -#define LSM_ID_APPARMOR        105
>>>>> -#define LSM_ID_YAMA        106
>>>>> -#define LSM_ID_LOADPIN        107
>>>>> -#define LSM_ID_SAFESETID    108
>>>>> -#define LSM_ID_LOCKDOWN        109
>>>>> -#define LSM_ID_BPF        110
>>>>> -#define LSM_ID_LANDLOCK        111
>>>>> +#define LSM_ID_APPARMOR        104
>>>>> +#define LSM_ID_YAMA        105
>>>>> +#define LSM_ID_LOADPIN        106
>>>>> +#define LSM_ID_SAFESETID    107
>>>>> +#define LSM_ID_LOCKDOWN        108
>>>>> +#define LSM_ID_BPF        109
>>>>> +#define LSM_ID_LANDLOCK        110
>>>>>      /*
>>>>>     * LSM_ATTR_XXX definitions identify different LSM attributes
>>