Messages in this thread | | | Date | Sat, 8 Oct 2011 20:02:11 +0000 | From | "Serge E. Hallyn" <> | Subject | Re: [PATCH] user namespace: make signal.c respect user namespaces |
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Quoting Oleg Nesterov (oleg@redhat.com): > On 09/25, Serge E. Hallyn wrote: > > > > Quoting Oleg Nesterov (oleg@redhat.com): > > > On 09/23, Serge E. Hallyn wrote: > > > > > > > > Quoting Oleg Nesterov (oleg@redhat.com): > > > > > On 09/23, Serge E. Hallyn wrote: > > > > > > > > > > > > It looks like I can fix all the > > > > > > cases > > > > > > > > > > except ptrace_signal(). Although we can simply ignore this case, imho. > > > > > > > > ptrace_signal() calls send_signal() though. > > > > > > Confused... I meant the "if (signr != info->si_signo)" case. This is > > > simple, and I only meant that this case is not that important. > > > > Yes, that's the case I was talking about. That then proceeds through > > send_signal(). > > It doesn't? I am even more confuused. Anyway, your patch adds map_cred_ns() > into ptrace_signal(). > > > The whole new patch (so far only compile-tested) is below. > > Perhaps I missed something, but it looks overcomplicated. I was thinking > about the (uncompiled/untested) simple patch below (it ignores ptrace_signal > for clarity). > > And note that this way we do not need to modify do_notify_parent*() > or ipc/mqueue.c:__do_notify() (your patch doesn't cover the latter). > Unless I missed something of course. > > And we do not need to handle the SEND_SIG_NOINFO case separately. > > > However, we still have the problems with sigqueueinfo, > > > > > > > by checking whether si_fromuser(info) > > > > > > > > > > I am not sure... sys_rt_queueinfo() is nasty. Plus we have to handle > > > > > the "fromkernel" case too. May be we can ignore this too. > > > > > > > > sys_rt_tgsigqueueinfo() still seems to go through send_signal(). > > > > > > Yes. But how can you fix si_uid? We do not even know if it exists. > > > Please look at siginfo/_uid, there is a union. We can't know what > > > the caller of sys_rt_sigqueueinfo() puts in this location. > > > > But it's a union alongside the pid. > > Again, I do not understand... Yes, we have the same problem with > > if (from_ancestor_ns) > q->info.si_pid = 0; > > This was discussed, we do not know what we can do. My point was, this > change is not sigqueueinfo-friendly too. > > Oleg. > > --- x/kernel/signal.c > +++ x/kernel/signal.c > @@ -1019,6 +1019,27 @@ static inline int legacy_queue(struct si > return (sig < SIGRTMIN) && sigismember(&signals->signal, sig); > } > > +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:
After looking a bit more, I really think the __SI_CHLD case just needs to always be converted at the callers (i.e. do_notify_parent).
> + case __SI_MESGQ:
This can be done like this, but if this is going to be the only case of a SI_FROMKERNEL not being converted at the caller, and there is aiui only one caller (__do_notivy in ipc/mmqueue.c), it seems better to just have fixup_uid() always return for SI_FROMKERNEL(info).
Does that sound ok?
If so, I'll whip up the patch and send it out after some testing. (If not, I'll try to better understand :)
> + 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) { > /* >
thanks, -serge
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