Messages in this thread | | | Subject | Re: [PATCH] prctl: add PR_[GS]ET_KILLABLE | From | Jürg Billeter <> | Date | Wed, 01 Aug 2018 09:43:57 +0200 |
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On Tue, 2018-07-31 at 18:26 +0200, Jann Horn wrote: > On Mon, Jul 30, 2018 at 10:01 AM Jürg Billeter <j@bitron.ch> wrote: > > [...] > > diff --git a/kernel/sys.c b/kernel/sys.c > > index 38509dc1f77b..264de630d548 100644 > > --- a/kernel/sys.c > > +++ b/kernel/sys.c > > [...] > > + case PR_SET_KILLABLE: > > + if (arg2 != 1 || arg3 || arg4 || arg5) > > + return -EINVAL; > > + me->signal->flags &= ~SIGNAL_UNKILLABLE; > > + break; > > I don't have an opinion on this patchset otherwise, but should this > prctl maybe block PR_SET_KILLABLE if you're actually the real init > process? This seems like it could potentially lead to weird things.
While I don't expect global init to use this, I can't think of a good reason to disallow it in the kernel. Do you have specific concerns or is the code in kernel/fork.c the only reason? I prefer avoiding special cases unless really required.
> This code in kernel/fork.c seems to rely on the fact that global init > is SIGNAL_UNKILLABLE, and probably also leads to weirdness if > container init is non-SIGNAL_UNKILLABLE:
Yes, Oleg has mentioned this as well. I have to change copy_process() to directly check for the PID namespace root process instead of checking for SIGNAL_UNKILLABLE.
Jürg
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