linux-kernel - Re: [PATCH v1 4/8] LSM: Maintain a table of LSM attribute data

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Date:   Thu, 27 Oct 2022 10:08:23 -0700
From:   Casey Schaufler <casey@...aufler-ca.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     casey.schaufler@...el.com, paul@...l-moore.com,
        linux-security-module@...r.kernel.org, jmorris@...ei.org,
        keescook@...omium.org, john.johansen@...onical.com,
        penguin-kernel@...ove.sakura.ne.jp, stephen.smalley.work@...il.com,
        linux-kernel@...r.kernel.org, linux-api@...r.kernel.org,
        mic@...ikod.net, casey@...aufler-ca.com
Subject: Re: [PATCH v1 4/8] LSM: Maintain a table of LSM attribute data

On 10/26/2022 11:29 PM, Greg KH wrote:
> On Wed, Oct 26, 2022 at 05:38:21PM -0700, Casey Schaufler wrote:
>> On 10/25/2022 11:00 PM, Greg KH wrote:
>>> On Tue, Oct 25, 2022 at 11:45:15AM -0700, Casey Schaufler wrote:
>>>> As LSMs are registered add their lsm_id pointers to a table.
>>>> This will be used later for attribute reporting.
>>>>
>>>> Signed-off-by: Casey Schaufler <casey@...aufler-ca.com>
>>>> ---
>>>>  include/linux/security.h | 17 +++++++++++++++++
>>>>  security/security.c      | 18 ++++++++++++++++++
>>>>  2 files changed, 35 insertions(+)
>>>>
>>>> diff --git a/include/linux/security.h b/include/linux/security.h
>>>> index ca1b7109c0db..e1678594d983 100644
>>>> --- a/include/linux/security.h
>>>> +++ b/include/linux/security.h
>>>> @@ -138,6 +138,23 @@ enum lockdown_reason {
>>>>  
>>>>  extern const char *const lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1];
>>>>  
>>>> +#define LSMID_ENTRIES ( \
>>>> +	1 + /* capabilities */ \
>>> No #define for capabilities?
>> Nope. There isn't one. CONFIG_SECURITY takes care of it.
>>
>>>> +	(IS_ENABLED(CONFIG_SECURITY_SELINUX) ? 1 : 0) + \
>>>> +	(IS_ENABLED(CONFIG_SECURITY_SMACK) ? 1 : 0) + \
>>>> +	(IS_ENABLED(CONFIG_SECURITY_TOMOYO) ? 1 : 0) + \
>>>> +	(IS_ENABLED(CONFIG_SECURITY_IMA) ? 1 : 0) + \
>>>> +	(IS_ENABLED(CONFIG_SECURITY_APPARMOR) ? 1 : 0) + \
>>>> +	(IS_ENABLED(CONFIG_SECURITY_YAMA) ? 1 : 0) + \
>>>> +	(IS_ENABLED(CONFIG_SECURITY_LOADPIN) ? 1 : 0) + \
>>>> +	(IS_ENABLED(CONFIG_SECURITY_SAFESETID) ? 1 : 0) + \
>>>> +	(IS_ENABLED(CONFIG_SECURITY_LOCKDOWN) ? 1 : 0) + \
>>>> +	(IS_ENABLED(CONFIG_BPF_LSM) ? 1 : 0) + \
>>>> +	(IS_ENABLED(CONFIG_SECURITY_LANDLOCK) ? 1 : 0))
>>>> +
>>>> +extern int lsm_id;
>>> u64?
>> u32. I doubt we'll get more than 32K security modules.
> These should be bits, not values, right?

lsm_id is the count of security modules that are registered.
It seemed like a good name for the value at the time, but as
it's causing confusion I should probably change it.

> Wait, this magic entry value is going to change depeneding on what is,
> or is not, enabled.  How is that a stable user/kernel api at all?
>
> confused.

I'll clarify.

This patch isn't implementing an API, but is required by subsequent
patches that do. Does linux-api want to see patches that are in support
of APIs, or just those with actual API implementation?

Thank you.

> greg k-h