Preferred subj= with multiple LSMs

[Casey Schaufler]

On 7/16/2019 9:14 AM, Steve Grubb wrote:
> On Tuesday, July 16, 2019 12:00:05 PM EDT Casey Schaufler wrote:
>>
>> Unless there's an objection I will use this format with
>> a slight modification. Smack allows commas in labels, so
>> using a bare comma can lead to ambiguity.
>>
>> lsms=smack,apparmor subj="TS/Alpha,Beta","a"

Oops! '/' isn't allowed in a Smack label. How embarrassing is that?

>>
>> It's more code change than some of the other options,
>> but if it has the best chance of working with user space
>> I'm game.
> Quoting has a specific meaning in audit fields. So, we really shouldn't do 
> that. We can simply pick another field delimiter. I really don't care which it 
> is as long as its illegal for use in a label. For example, we use 
>
> #define AUDIT_KEY_SEPARATOR 0x01
>
> to separate key fields. We can pick almost anything. (exclamation mark, semi-
> colon, hash, plus symbol, tilde, 0x02, whatever) But it will need to be 
> documented and put into the API so that everyone is aware of the convention.

Unless there's objection I'll document and use '/',

lsms=selinux,apparmor subj=a:b:c:d/a

If there is objection without alternative presented I'll use 0x02,
because no one (I hope) is going to allow that in their label, and
keys have set precedence for unprintable characters.

>
> -Steve
>
>