Re: [PATCH v1 2/8] LSM: Add an LSM identifier for external use

Casey Schaufler
2022-11-10T00:47:02Z

On 11/9/2022 3:33 PM, Paul Moore wrote:
> On Tue, Oct 25, 2022 at 2:45 PM Casey Schaufler <casey@schaufler-ca.com> wrote:
>> Add an integer member "id" to the struct lsm_id. This value is
>> a unique identifier associated with each security module. The
>> values are defined in a new UAPI header file. Each existing LSM
>> has been updated to include it's LSMID in the lsm_id.
>>
>> The LSM ID values are sequential, with the oldest module
>> LSM_ID_CAPABILITY being the lowest value and the existing
>> modules numbered in the order they were included in the
>> main line kernel. The first 32 values (0 - 31) are reserved
>> for some as yet unknown but important use.
>>
>> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
>> ---
>> include/linux/lsm_hooks.h | 1 +
>> include/uapi/linux/lsm.h | 32 ++++++++++++++++++++++++++++++++
>> security/apparmor/lsm.c | 2 ++
>> security/bpf/hooks.c | 2 ++
>> security/commoncap.c | 2 ++
>> security/landlock/setup.c | 2 ++
>> security/loadpin/loadpin.c | 2 ++
>> security/lockdown/lockdown.c | 2 ++
>> security/safesetid/lsm.c | 2 ++
>> security/selinux/hooks.c | 2 ++
>> security/smack/smack_lsm.c | 2 ++
>> security/tomoyo/tomoyo.c | 2 ++
>> security/yama/yama_lsm.c | 2 ++
>> 13 files changed, 55 insertions(+)
>> create mode 100644 include/uapi/linux/lsm.h
> Unless you're getting paid by the patch, I'd rather you combine
> patches 1/8 and 2/8 into a single patch. They are both pretty small,
> very related, and I don't want to see 1/8 merged anywhere without 2/8.

OK by me. One less compile+test cycle. It's nice to know there's some
limit on patch granularity.

>
>> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
>> index e383e468f742..dd4b4d95a172 100644
>> --- a/include/linux/lsm_hooks.h
>> +++ b/include/linux/lsm_hooks.h
>> @@ -1607,6 +1607,7 @@ struct security_hook_heads {
>> */
>> struct lsm_id {
>> const char *lsm; /* Name of the LSM */
>> + int id; /* LSM ID */
>> };
> At the very least let's define lsm_id::id as an 'unsigned int' type,
> but since we are going to see the lsm_id::id token used as part of the
> kernel ABI (likely not in this struct) I agree with Greg's comments
> about making the size more explicit. I would suggest __u32/u32 as
> 32-bits should be plenty for this token.
>
> Given the other upstream discussions we may want to do something
> similar with lsm_id::lsm and __u8/u8. I'm pretty sure I saw a similar
> comment (by Greg?) elsewhere in this patchset when I was quickly
> skimming these on my phone while away ...

Yes. The API friendly typing will be in the next revision.

> --
> paul-moore.com