[GIT PULL] Add trusted_for(2) (was O_MAYEXEC)

[Mickaël Salaün]

On 08/02/2023 20:32, Kees Cook wrote:
> *thread necromancy*
> 
> On Tue, Apr 05, 2022 at 06:09:03PM +0200, Mickaël Salaün wrote:
>>
>> On 05/04/2022 01:26, Linus Torvalds wrote:
>>> On Mon, Apr 4, 2022 at 3:25 PM Kees Cook <keescook at chromium.org> wrote:
>>
>> [...]
>>
>>>
>>>> I think this already exists as AT_EACCESS? It was added with
>>>> faccessat2() itself, if I'm reading the history correctly.
>>>
>>> Yeah, I noticed myself, I just hadn't looked (and I don't do enough
>>> user-space programming to be aware of if that way).
>>
>> I think AT_EACCESS should be usable with the new EXECVE_OK too.
>>
>>
>>>
>>>>>       (a) "what about suid bits that user space cannot react to"
>>>>
>>>> What do you mean here? Do you mean setid bits on the file itself?
>>>
>>> Right.
>>>
>>> Maybe we don't care.
>>
>> I think we don't. I think the only corner case that could be different is
>> for files that are executable, SUID and non-readable. In this case it
>> wouldn't matter because userspace could not read the file, which is required
>> for interpretation/execution. Anyway, S[GU]ID bits in scripts are just
>> ignored by execve and we want to follow the same semantic.
> 
> Hi Mickaël,
> 
> Is there a new version of this being worked on? It would be really nice
> to have the O_MAYEXEC/faccessat2() visibility for script execution control
> in userspace. It seems like it would be mainly a respin of an earlier
> version of this series before trusted_for() was proposed.

Yes, I plan to send a new version in a few weeks.

> 
> -Kees
>