Messages in this thread | | | From | David Drysdale <> | Date | Thu, 10 Sep 2015 14:51:28 +0100 | Subject | Re: RFC: fsyscall |
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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) ?
> 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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