linux-kernel - Re: [PATCH v3 04/13] task_isolation: userspace hard isolation from kernel

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Date:   Sun, 19 Apr 2020 05:07:41 +0000
From:   Alex Belits <abelits@...vell.com>
To:     "luto@...capital.net" <luto@...capital.net>
CC:     "mingo@...nel.org" <mingo@...nel.org>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "linux-api@...r.kernel.org" <linux-api@...r.kernel.org>,
        "rostedt@...dmis.org" <rostedt@...dmis.org>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
        Prasun Kapoor <pkapoor@...vell.com>,
        "catalin.marinas@....com" <catalin.marinas@....com>,
        "frederic@...nel.org" <frederic@...nel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "will@...nel.org" <will@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v3 04/13] task_isolation: userspace hard isolation from
 kernel


On Thu, 2020-04-09 at 11:00 -0700, Andy Lutomirski wrote:
> 
> > 
> > Once the task has returned to userspace after issuing the prctl(),
> > if it enters the kernel again via system call, page fault, or any
> > other exception or irq, the kernel will kill it with SIGKILL.
> 
> I could easily imagine myself using task isolation, but not with the
> SIGKILL semantics. SIGKILL causes data loss. Please at least let
> users choose what signal to send.

This is already done, even though the documentation is not updated.
There is even a userspace library that deals with this while
compensating for possible race conditions on isolation entry and
automatic re-entry after isolation is broken: 
https://github.com/abelits/libtmc

-- 
Alex