Re: capabilities carried over execve()

From: Pavel Machek (
Date: Thu Apr 26 2001 - 15:10:49 EST


> I am attempting to write an init replacement that is capability-smart.
> Though I'm pleased that prctl() lets me keep capabilities across a
> setreuid(), maintaining caps over execve() seems impossible to do right.
> I currently see a few options:
> - use the CLOEXEC-pipe hack that execcap uses (parent notices
> when pipe closes then rushes to set caps on child before
> child notices they're gone). This looks like a race to me.
> - tweak linux/fs/exec.c (prepare_binprm) to pretend that all
> files have cap_inheritable and cap_effective fully set.
> This seems a more elegant solution, but requires a kernel
> patch.
> - exec the child in a stopped state, mess with caps, then
> send it SIGCONT. AFAIK, there is no way to do
> execve_and_stop.

What about ptrace? It should be able to do this kind of stuff... but
it is going to be messy.

I'm "In my country we have almost anarchy and I don't care."
Panos Katsaloulis describing me w.r.t. patents at
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This archive was generated by hypermail 2b29 : Mon Apr 30 2001 - 21:00:17 EST