Messages in this thread | | | Date | Tue, 27 Sep 2011 10:27:11 -0500 | From | Serge Hallyn <> | Subject | Re: [PATCH] user namespace: make signal.c respect user namespaces |
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Quoting Oleg Nesterov (oleg@redhat.com): > 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().
Oh, well not always, but it does in the case where sigismember(¤t->blocked, signr); But I suppose that's not a common path :)
> 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.
Ok.
> > > +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().
True.
> Or we can simply leave this code as is. I do not think this si_uid > (in this case) is really important.
Ok, that sounds good to me.
thanks, -serge
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