"Serge E. Hallyn" <serge@xxxxxxxxxx> writes:
> ipc/mqueue.c: for __SI_MESQ, convert the uid being sent to recipient's
> user namespace. (new, thanks Oleg)
>
> __send_signal: convert current's uid to the recipient's user namespace
> for any siginfo which is not SI_FROMKERNEL (patch from Oleg, thanks
> again :)
>
> do_notify_parent and do_notify_parent_cldstop: map task's uid to parent's
> user namespace
>
> ptrace_signal maps parent's uid into current's user namespace before
> including in signal to current. IIUC Oleg has argued that this shouldn't
> matter as the debugger will play with it, but it seems like not converting
> the value currently being set is misleading.
>
> Changelog:
> Sep 20: Inspired by Oleg's suggestion, define map_cred_ns() helper to
> simplify callers and help make clear what we are translating
> (which uid into which namespace). Passing the target task would
> make callers even easier to read, but we pass in user_ns because
> current_user_ns() != task_cred_xxx(current, user_ns).
> Sep 20: As recommended by Oleg, also put task_pid_vnr() under rcu_read_lock
> in ptrace_signal().
> Sep 23: In send_signal(), detect when (user) signal is coming from an
> ancestor or unrelated user namespace. Pass that on to __send_signal,
> which sets si_uid to 0 or overflowuid if needed.
> Oct 12: Base on Oleg's fixup_uid() patch. On top of that, handle all
> SI_FROMKERNEL cases at callers, because we can't assume sender is
> current in those cases.
> Nov 10: (mhelsley) rename fixup_uid to more meaningful usern_fixup_signal_uid
> Nov 10: (akpm) make the !CONFIG_USER_NS case clearer
>
> @@ -1088,6 +1117,9 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
> q->info.si_pid = 0;
> break;
> }
> +
> + userns_fixup_signal_uid(info, t);
There is a small bug here. You want to fixup q->info, not info.
Otherwise you might try dereferencing one of the special signals and get
a NULL pointer dereference.
Eric
> +
> } else if (!is_si_special(info)) {
> if (sig >= SIGRTMIN && info->si_code != SI_USER) {
> /*
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