Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
References: <20190128084959.13060-1-vincent.whitchurch@axis.com>
 <20190128100545.b62193aa8f49e1de8d6ea8b7@linux-foundation.org> <20190130144851.GK11489@garbanzo.do-not-panic.com>
In-Reply-To: <20190130144851.GK11489@garbanzo.do-not-panic.com>
From:   Richard Weinberger <richard.weinberger@gmail.com>
Date:   Wed, 30 Jan 2019 16:02:36 +0100
Message-ID: <CAFLxGvyUpWRE3SWD2eX+M-TGKv7+6At0zsYYTTWw0y6gs3M4iw@mail.gmail.com>
Subject: Re: [PATCH v2] sysctl: Add panic-fatal-signals
To:     Luis Chamberlain <mcgrof@kernel.org>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Vincent Whitchurch <vincent.whitchurch@axis.com>,
        Kees Cook <keescook@chromium.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Vincent Whitchurch <rabinv@axis.com>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wed, Jan 30, 2019 at 3:49 PM Luis Chamberlain <mcgrof@kernel.org> wrote:
>
> On Mon, Jan 28, 2019 at 10:05:45AM -0800, Andrew Morton wrote:
> > On Mon, 28 Jan 2019 09:49:59 +0100 Vincent Whitchurch <vincent.whitchurch@axis.com> wrote:
> > > --- a/init/Kconfig
> > > +++ b/init/Kconfig
> > > @@ -1242,6 +1242,20 @@ config SYSCTL_SYSCALL
> > >
> > >       If unsure say N here.
> > >
> > > +config SYSCTL_PANIC_FATAL_SIGNALS
> > > +   bool "panic-fatal-signals sysctl" if EXPERT
> > > +   depends on PROC_SYSCTL
> > > +   help
> > > +     If you say Y here, a kernel.panic-fatal-signals sysctl will be
> > > +     offered.  If this sysctl is turned on, the kernel will panic if any
> > > +     userspace process receives a fatal signal which would trigger a core
> > > +     dump.
> > > +
> > > +     When used together with kernel core dumps, this can be useful for
> > > +     debugging some system-wide problems, primarily on embedded systems.
> > > +
> > > +     If unsure, say N.
> >
> > I suggest that the Kconfig help and the forthcoming documentation
> > should clearly explain the dangers of enabling this!
>
> And so, should default to n.
>
>   Luis

Hmm, why can't this be a core dump helper?
Such as:

#!/bin/sh
# Usage:
# echo "|/root/crash.sh %p %e %s" > /proc/sys/kernel/core_pattern

PID="$1"
COMM="$2"
SIGNAL="$3"

echo "$COMM ($PID) died by signal $SIGNAL, killing kernel" > /dev/kmsg
echo c > /proc/sysrq-trigger

-- 
Thanks,
//richard