Messages in this thread | | | Date | Thu, 10 Sep 2015 08:43:50 -0500 | From | "Serge E. Hallyn" <> | Subject | Re: RFC: fsyscall |
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On Tue, Sep 08, 2015 at 07:25:17PM -0500, Eric W. Biederman wrote: > Andy Lutomirski <luto@amacapital.net> writes: > > > On Tue, Sep 8, 2015 at 4:07 PM, Eric W. Biederman <ebiederm@xmission.com> wrote: > > >> Perhaps I had missed it but I don't recall capsicum being able to wrap > >> things like reboot(2). > >> > > > > Ah, so you want to be able to grant BPF-defined capabilities :) > > Pretty much. > > Where I am focusing is turning Posix capabilities into real > capabilities. I would not mind if the functionality was a bit more > general. Say to be able to handle things like security labels, or > anywhere else you might reasonably be asked can you do X? > > But I would be happy if we just managed to wrap the Posix capabilities > and turned them into real capablilities.
If there were a clever way to exec an open fd, then you could do this by passing an fd to a copy of /bin/reboot which has fP=CAP_SYS_BOOT, or prefereably fI=CAP_SYS_BOOT,fE=1 and leave pI=CAP_SYS_BOOT in the task.
A cleaner way to do this is to have a service which can reboot, which looks at unix socket peercreds to determine whether the granter may reboot, then passes it an fd which the granter may pass to a grantee. Then the grantee passes the fd to the service, which recognizes it and reboots.
-serge
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