[CRIU] [PATCH] security: check_ids - return true if [se]?[ug]id is the same as task id

[Ruslan Kuprieiev]

After a bit more thinking I don't like the idea of checking owner and 
perms at all.
And I think we should create images with owner == current user.
Let me explain why.
Lets imagine, I'm a developer of, for example, a game, who wants to save by
dumping and load by restoring( well, why not?=) ). I want to be able to 
delete some old saves, but currently i'm not able, because images are 
owned by root and
perms == 0644.
Playing the game as root isn't cool =).

Still, there is a bug, when one can't dump/restore process which 
r/e/sgid doesn't
match user crgid. crgid is primary group of the user and if it doesn't 
match sgid
it doesn't mean that user isn't in additional group sgid.
So, it looks like we should divide uid and gid checking. For gid 
checking we should
compare crgid with additional groups of the user.

On 17.06.2014 17:25, Pavel Emelyanov wrote:
> On 06/17/2014 06:18 PM, Ruslan Kuprieiev wrote:
>> ~snip~
>> So, just to be sure that I get it right. Here is the plan:
>> -- make criu create images with rw-r--r-- perms owned by root
>> -- on restore, make sure that images are rw-r--r-- and owned by root, and if
>>       smth wrong, don't allow non-root to restore
> No, don't allow restoration of "extended prio" like changed xids and
> non zero caps.
>
>> -- use that check from kill_ok_by_creds to determine whether or not
>> non-root user
>>       is allowed to dump/restore
> No, regular user cannot change to another user or raise its caps by
> changing images. This has nothing to do with kill_ok_by_creds.
>
> Thanks,
> Pavel