Re: [PATCH] prctl: require checkpoint_restore_ns_capable for PR_SET_MM_MAP

[David Hildenbrand (Arm)]

On 4/2/26 15:13, Oleg Nesterov wrote:
> Note also the comment above validate_prctl_map_addr() called by
> prctl_set_mm_map(), "we don't require any capability here ...".
> 
> Oleg.
> 
> On 04/02, Oleg Nesterov wrote:
>>
>> On 04/02, Qi Tang wrote:
>>>
>>> The original commit f606b77f1a9e ("prctl: PR_SET_MM -- introduce
>>> PR_SET_MM_MAP operation") states "we require the caller to be at least
>>> user-namespace root user", but this was never enforced in the code.
>>>
>>> Add a checkpoint_restore_ns_capable() check at the top of
>>> prctl_set_mm_map(), after the PR_SET_MM_MAP_SIZE early return.  This
>>> requires CAP_CHECKPOINT_RESTORE or CAP_SYS_ADMIN in the caller's
>>> user namespace, matching the stated design intent and the existing
>>> check for exe_fd changes.
>>
>> Can't really comment... but if you add this check at the start, then you
>> should also remove the same checkpoint_restore_ns_capable() check below?
>> In the "if (prctl_map.exe_fd != (u32)-1)" block.
>>
>

I'll note that the man page is wrong as well.

PR_SET_MM lists PR_SET_MM_MAP, but states "The calling process must have
the CAP_SYS_RESOURCE capability."

-- 
Cheers,

David