linux-kernel - Re: [PATCH v36 21/24] x86/vdso: Implement a vDSO for Intel SGX enclave call

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20200813193842.GV29439@linux.intel.com>
Date:   Thu, 13 Aug 2020 12:38:42 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Andy Lutomirski <luto@...capital.net>
Cc:     Andy Lutomirski <luto@...nel.org>,
        Nathaniel McCallum <npmccallum@...hat.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        X86 ML <x86@...nel.org>, linux-sgx@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>,
        Jethro Beekman <jethro@...tanix.com>,
        Cedric Xing <cedric.xing@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        asapek@...gle.com, Borislav Petkov <bp@...en8.de>,
        chenalexchen@...gle.com, Conrad Parker <conradparker@...gle.com>,
        cyhanish@...gle.com, Dave Hansen <dave.hansen@...el.com>,
        "Huang, Haitao" <haitao.huang@...el.com>,
        Josh Triplett <josh@...htriplett.org>,
        "Huang, Kai" <kai.huang@...el.com>,
        "Svahn, Kai" <kai.svahn@...el.com>, Keith Moyer <kmoy@...gle.com>,
        Christian Ludloff <ludloff@...gle.com>,
        Neil Horman <nhorman@...hat.com>,
        Patrick Uiterwijk <puiterwijk@...hat.com>,
        David Rientjes <rientjes@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>, yaozhangx@...gle.com
Subject: Re: [PATCH v36 21/24] x86/vdso: Implement a vDSO for Intel SGX
 enclave call

On Tue, Aug 11, 2020 at 08:16:54AM -0700, Andy Lutomirski wrote:
> 
> > On Aug 10, 2020, at 5:52 PM, Andy Lutomirski <luto@...capital.net> wrote:
> > 
> > 
> >>> On Aug 10, 2020, at 4:48 PM, Sean Christopherson <sean.j.christopherson@...el.com> wrote:
> >>> 
> >>> On Mon, Aug 10, 2020 at 04:08:46PM -0700, Andy Lutomirski wrote:
> >>> What am I missing?  I still don't really understand why we are
> >>> supporting this mechanism at all.  Just the asm code to invoke the
> >>> callback seems to be about half of the entire function.
> >> 
> >> Because the Intel SDK (and other SDKs?) wants to use the host stack to pass
> >> parameters out of the enclave.
> > 
> > Ugh, right.  I forgot about that particular abomination.
> > 
> > I suppose that passing a context pointer would be reasonable.
> 
> The alternative would be to pass in a parameter that gets put in RSP before
> entering the enclave. The idea is that the untrusted runtime would allocate a
> couple pages with guard pages at either end, and enclaves using the
> regrettable arguments-on-the-stack scheme would end up using the alternative
> stack.
> 
> At the end of the day, none of this really matters too much. Languages that
> can do inline asm but can’t do container_of() can get fixed or use
> workarounds.

So, is your "official" opinion

   Go update the vDSO to allow passing an arbitrary pointer.

or

   Eh, don't bother.