Messages in this thread | | | From | Andy Lutomirski <> | Date | Wed, 4 Feb 2015 08:34:31 -0800 | Subject | Re: [capabilities] Allow normal inheritance for a configurable set of capabilities |
| |
On Wed, Feb 4, 2015 at 8:12 AM, Andrew G. Morgan <morgan@kernel.org> wrote: > I was thinking more like this: > > int override = secure(SECURE_AMBIENT_PRIVS) && > cap_isclear(caps->inheritable.cap); > > CAP_FOR_EACH_U32(i) { > __u32 permitted = caps->permitted.cap[i]; > __u32 inheritable = override ? new->cap_bset.cap[i] : > caps->inheritable.cap[i]; > [...]
To elaborate on my objection:
For better or for worse, as a practical matter, if you drop a cap from pP but keep it in pI, there's no way to get that cap back on the average system to get that cap back using execve because nothing will have that bit set in fI. I am not at all confident that changing this is safe at this point, since there's lots of legacy code out there.
So, how about:
__u32 inheritable = override ? (new->cap_bset.cap[i] & permitted) : caps->inheritable.cap[i];
instead?
This still doesn't address the effective set adequately, I think. I suspect that we'll want to always start with pE' == pP' in the new mode, or perhaps pE' = (pP' & pE). This latter part is also a bit dangerous and furthers my desire to restrict this to no_new_privs.
--Andy
| |