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    SubjectRe: [PATCH] user namespace: make signal.c respect user namespaces
    Sorry, I missed this email...

    On 10/04, Serge E. Hallyn wrote:
    >
    > Quoting Oleg Nesterov (oleg@redhat.com):
    > > --- 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:
    >
    > If I'm reading this right, this will catch do_notify_parent, which is
    > sending signals not from current.

    Argh, indeed. So we need to modify the callers.

    OTOH, this is only possible if the debugger notifies tracee->real_parent,
    or we reparent to /sbin/init.

    Anyways, yes, I forgot about this. Thanks.

    Oleg.

    Not sure of the best way to avoid
    > this. For pids that case is being ignored by not using the __SI_MASK,
    > so CLD_EXITED etc will cause from_ancestor_ns to be false. Could we
    > do that here too, and then translate the pids in do_notify_parent?
    >
    > > + 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) {
    > > /*
    > >



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