Messages in this thread | | | Date | Mon, 22 Dec 2008 23:58:25 +0100 | From | Oleg Nesterov <> | Subject | Re: [RFC][PATCH 6/6][v3] Protect cinit from blocked fatal signals |
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On 12/20, Sukadev Bhattiprolu wrote: > > +static int sig_unkillable(struct signal_struct *signal, int sig) > +{ > + if (signal->flags & SIGNAL_UNKILLABLE_FROM_NS) > + return !sig_kernel_only(sig); > + > + /* > + * We must have dropped SIGKILL/SIGSTOP in sig_ignored() > + * TODO: Remove BUG_ON(). > + */ > + BUG_ON(signal->flags & SIGNAL_UNKILLABLE && sig_kernel_only(sig)); > + > + return (signal->flags & SIGNAL_UNKILLABLE); > +} > + > int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka, > struct pt_regs *regs, void *cookie) > { > @@ -1907,9 +1943,10 @@ relock: > > /* > * Global init gets no signals it doesn't want. > + * Container-init gets no signals it doesn't want from same > + * container. > */ > - if (unlikely(signal->flags & SIGNAL_UNKILLABLE) && > - !signal_group_exit(signal)) > + if (sig_unkillable(signal, signr) && !signal_group_exit(signal)) > continue;
Again, I do not understand why do we need SIGNAL_UNKILLABLE_FROM_NS.
I thought about the change in get_signal_to_deliver() during the previous discussion, and I think what we need is:
if (unlikely(signal->flags & SIGNAL_UNKILLABLE) && !sig_kernel_only(sig)) continue;
and this was yet another reason for "protect init from unwanted signals more".
Because, if we see SIGKILL/SIGSTOP here, this means that the signal was sent from the parent ns, or it was generated "internally", for example by sys_exit_group().
Oleg.
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