# Re: \[PATCH\] capabilities: Ambient capability set V2

- From: Christoph Lameter \<hidden\>
- Date: 2015-03-05 18:41:42 
- List: linux-api
- Page: https://ratatoskr.run/linux-api/2015/03/4444266
- Thread: https://ratatoskr.run/linux-api/2015/02/4438585/t.md

```text
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.
```