# Re: \[PATCH\] capabilities: Ambient capability set V1

- From: Christoph Lameter \<hidden\>
- Date: 2015-02-26 18:28:37 
- List: linux-api
- Page: https://ratatoskr.run/linux-api/2015/02/4438449
- Thread: https://ratatoskr.run/linux-api/2015/02/4426512/t.md

```text
On Thu, 26 Feb 2015, Serge E. Hallyn wrote:

> > Well doing that breaks su.
>
> Don't what exactly?  You're saying that doing
>
> pI' = pI
> pA' = pA  (pA is ambient)
> pP' = (X & fP) | (pI & (fI | pA))
> pE' = pP' & (fE | pA)
>
> stopped su from having CAP_SETGID while
>
> pI' = pI
> pA' = pA  (pA is ambient)
> pP' = (X & fP) | (pI & (fI | pA))
> pE' = pP' & fE
>
> worked?  I'll hope you're saying both "fail", in which case

fE does not exist in cpu_vfs_cap_data. We only get fI and fP. Why in the
world does setcap allow setting fE?

V1 does not use fE. In my newer attempt, I seemed to have worked
with zeroed field that I assumed was filled in.

I will just do

pE' = pP'

Ok?
```