Messages in this thread | | | Date | Thu, 10 Sep 2015 09:01:20 -0500 | From | "Serge E. Hallyn" <> | Subject | Re: RFC: fsyscall |
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On Thu, Sep 10, 2015 at 02:51:28PM +0100, David Drysdale wrote: > On Thu, Sep 10, 2015 at 2:43 PM, Serge E. Hallyn <serge@hallyn.com> wrote: > > 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 > > execveat(fd, "", argv, envp, AT_EMPTY_PATH) ?
??? I looked for it but I don't have a manpage for it. I see it at man7.org though. Thanks :)
> > 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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