Re: [PATCH] capabilities: Ambient capability set V2

From: Christoph Lameter
Date: Thu Mar 05 2015 - 13:41:45 EST

On Thu, 5 Mar 2015, Serge E. Hallyn wrote:

> > >
> > > So I'd say drop this change ^
> >
> > Then the ambient caps get ignored for a executables that have capabilities
> > seton the file?
> Yes. Those are assumed to already know what they're doing.

Do they? What if there is a LD_PRELOAD library that redirects socket calls
and that needs raw device access (there are actually a number of software
packages like that to reduce the latency of network I/O. See for example
Solarflare's software products and the current rsocket libary in OFED.
There are cap issues if the rsocket library should be made useful for
Ethernet instead of infiniband).

> Why? Do you foresee cases where a file that has fP set needs capabilities
> that aren't in its fP?

Yes due to the library issues.

> It seems more likely that they'll risk misbehaving due to an unexpected set
> of caps.

The userspace driver code in the library wont work since it does not have
the caps to access the raw device registers.
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