Messages in this thread | | | Date | Tue, 27 Sep 2011 16:38:35 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH] user namespace: make signal.c respect user namespaces |
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On 09/27, Serge Hallyn wrote: > > Quoting Oleg Nesterov (oleg@redhat.com): > > On 09/25, Serge E. Hallyn wrote: > > > > > > Yes, that's the case I was talking about. That then proceeds through > > > send_signal(). > > > > It doesn't? > > No, I was saying it *does*.
But it doesn't ;)
Serge, there is some misunderstanding. And I do not know who is confused, me or your.
ptrace_signal() simply fills *info with some "random" data before processing the signal. It doesn't pass this info to send_signal().
If the debuggure wants something meaningfull in *info, it should fill it itself via PTRACE_SETSIGINFO. This handles the case when the debugger doesn't really care and only changes signr.
> > +static inline fixup_uid(struct siginfo *info, struct task_struct *t) > > +{ > > +#ifdef CONFIG_USER_NS > > + if (current_user_ns() == task_cred_xxx(t, user_ns))) > > +#endif > > + return; > > + > > + if (SI_FROMKERNEL(info)) > > + switch (info->si_code & __SI_MASK) { > > + default: > > + return; > > + > > + case __SI_CHLD: > > + case __SI_MESGQ: > > + break; > > + } > > + > > + info->si_uid = user_ns_map_uid(task_cred_xxx(t, user_ns), > > + current_cred(), info->si_uid); > > +} > > + > > static int __send_signal(int sig, struct siginfo *info, struct task_struct *t, > > int group, int from_ancestor_ns) > > { > > @@ -1088,6 +1109,9 @@ static int __send_signal(int sig, struct > > q->info.si_pid = 0; > > break; > > } > > + > > + fixup_uid(info, t); > > + > > } else if (!is_si_special(info)) { > > if (sig >= SIGRTMIN && info->si_code != SI_USER) { > > /* > > It certainly is much simpler. I'll take some time to walk through all > of send_signal again and make sure I understand what it does in all > the cases.
Thanks.
As for ptrace_signal(), it can use the same helper too. Once again, debugger can use PTRACE_SETSIGINFO, if we really want to fixup si_uid we should do this even if signr == info->si_signo. OTOH, we do not know what debugger puts in this chunk of memory. This is like sigqueueinfo().
Or we can simply leave this code as is. I do not think this si_uid (in this case) is really important.
Oleg.
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