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Date:   Mon, 7 Feb 2022 08:30:50 -0800
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To:     Adrian Reber <adrian@lisas.de>, Mike Rapoport <rppt@kernel.org>
Cc:     Rick Edgecombe <rick.p.edgecombe@intel.com>, x86@kernel.org,
        "H . Peter Anvin" <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>,
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        linux-arch@vger.kernel.org, linux-api@vger.kernel.org,
        Arnd Bergmann <arnd@arndb.de>,
        Andy Lutomirski <luto@kernel.org>,
        Balbir Singh <bsingharora@gmail.com>,
        Borislav Petkov <bp@alien8.de>,
        Cyrill Gorcunov <gorcunov@gmail.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Eugene Syromiatnikov <esyr@redhat.com>,
        Florian Weimer <fweimer@redhat.com>,
        "H . J . Lu" <hjl.tools@gmail.com>, Jann Horn <jannh@google.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Kees Cook <keescook@chromium.org>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Nadav Amit <nadav.amit@gmail.com>,
        Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>,
        Peter Zijlstra <peterz@infradead.org>,
        Randy Dunlap <rdunlap@infradead.org>,
        "Ravi V . Shankar" <ravi.v.shankar@intel.com>,
        Dave Martin <Dave.Martin@arm.com>,
        Weijiang Yang <weijiang.yang@intel.com>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        joao.moreira@intel.com, John Allen <john.allen@amd.com>,
        kcc@google.com, eranian@google.com,
        Andrei Vagin <avagin@gmail.com>,
        Dmitry Safonov <0x7f454c46@gmail.com>
References: <20220130211838.8382-1-rick.p.edgecombe@intel.com>
 <YgAWVSGQg8FPCeba@kernel.org> <YgDIIpCm3UITk896@lisas.de>
From:   Dave Hansen <dave.hansen@intel.com>
Subject: Re: [PATCH 00/35] Shadow stacks for userspace
In-Reply-To: <YgDIIpCm3UITk896@lisas.de>
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On 2/6/22 23:20, Adrian Reber wrote:
>>> 	CRIU Support
>>> 	------------
>>> 	In the past there was some speculation on the mailing list about 
>>> 	whether CRIU would need to be taught about CET. It turns out, it does. 
>>> 	The first issue hit is that CRIU calls sigreturn directly from its 
>>> 	“parasite code” that it injects into the dumper process. This violates
>>> 	this shadow stack implementation’s protection that intends to prevent
>>> 	attackers from doing this.
...
>>From the CRIU side I can say that I would definitely like to see this
> resolved. CRIU just went through a similar exercise with rseq() being
> enabled in glibc and CI broke all around for us and other projects
> relying on CRIU. Although rseq() was around for a long time we were not
> aware of it but luckily 5.13 introduced a way to handle it for CRIU with
> ptrace. An environment variable existed but did not really help when
> CRIU is called somewhere in the middle of the container software stack.
> 
>>From my point of view a solution not involving an environment variable
> would definitely be preferred.

Have there been things like this for CRIU in the past?  Something where
CRIU needs control but that's also security-sensitive?

Any thoughts on how you would _like_ to see this resolved?