Re: [PATCH 0/2] capabilities
From: Andrew Morton
Date: Wed May 12 2004 - 20:57:03 EST
Andy Lutomirski <luto@xxxxxxxxxxxxx> wrote:
> > What if there are existing applications which are deliberately or
> > inadvertently relying upon the current behaviour? That seems unlikely, but
> > the consequences are gruesome.
> Like something that turns KEEPCAPS on then setuid()s then executes an
> untrusted program?
Or if it simply has caps and then does exec.
> > If I'm right in this concern, the fixed behaviour should be opt-in. That
> > could be via a new prctl() thingy but I think it would be better to do it
> > via a kernel boot parameter. Because long-term we should have the fixed
> > semantics and we should not be making people change userspace for some
> > transient 2.6-only kernel behaviour.
> The prctl would defeat the purpose (imagine if bash forgot the prctl --
> then the whole thing is pointless).
yup, lots of apps would need to be changed to interface with something
which won't be present in 2.8 kernels.
> I'll cook up the boot parameter in
> the next couple days (probably with a config option and some kind of
> warning that the old behavior is deprecated).
I wouldn't bother with a config option.
> Is it a problem if I make
> the changes to init's state unconditional? (I still don't see why
> CAP_SETPCAP is dangerous for root to have...)
I'd be more comfortable (ie: comfort level non-zero) if there was zero
behaviour change if the boot option isn't enabled.
> The only concern is that some new code relies on the new inheritable
> semantics. That shouldn't be so bad, though, since that's just an extra
> precaution (if there are insecure setuid binaries around, you already
> have problems).
Yes, we can live with that. The price of prior sins.
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