From: "H.J. Lu" <hjl.tools@gmail.com>
To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>,
Andrew Cooper <andrew.cooper3@citrix.com>,
"the arch/x86 maintainers" <x86@kernel.org>,
linux-sgx@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Jethro Beekman <jethro@fortanix.com>,
Cedric Xing <cedric.xing@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
asapek@google.com, Borislav Petkov <bp@alien8.de>,
chenalexchen@google.com, Conrad Parker <conradparker@google.com>,
cyhanish@google.com, Dave Hansen <dave.hansen@intel.com>,
"Huang, Haitao" <haitao.huang@intel.com>,
Josh Triplett <josh@joshtriplett.org>,
"Huang, Kai" <kai.huang@intel.com>,
"Svahn, Kai" <kai.svahn@intel.com>, Keith Moyer <kmoy@google.com>,
Christian Ludloff <ludloff@google.com>,
Neil Horman <nhorman@redhat.com>,
Nathaniel McCallum <npmccallum@redhat.com>,
Patrick Uiterwijk <puiterwijk@redhat.com>,
David Rientjes <rientjes@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
yaozhangx@google.com, Yu-cheng Yu <yu-cheng.yu@intel.com>
Subject: Re: [PATCH v38 21/24] x86/vdso: Implement a vDSO for Intel SGX enclave call
Date: Mon, 28 Sep 2020 15:06:35 -0700 [thread overview]
Message-ID: <CAMe9rOoyxtf_kUCdb-TN+NmZsQNmFY8NLMObSdCB5bBVq1x+cQ@mail.gmail.com> (raw)
In-Reply-To: <20200928215635.GF2705@linux.intel.com>
On Mon, Sep 28, 2020 at 2:56 PM Jarkko Sakkinen
<jarkko.sakkinen@linux.intel.com> wrote:
>
> On Mon, Sep 28, 2020 at 11:12:08AM -0700, Andy Lutomirski wrote:
> > On Mon, Sep 28, 2020 at 11:08 AM H.J. Lu <hjl.tools@gmail.com> wrote:
> > >
> > > On Mon, Sep 28, 2020 at 9:44 AM Andrew Cooper <andrew.cooper3@citrix.com> wrote:
> > > >
> > > > On 28/09/2020 01:58, Jarkko Sakkinen wrote:
> > > > > On Fri, Sep 25, 2020 at 07:23:59PM +0100, Andrew Cooper wrote:
> > > > >> On 15/09/2020 12:28, Jarkko Sakkinen wrote:
> > > > >>> diff --git a/arch/x86/entry/vdso/vsgx_enter_enclave.S b/arch/x86/entry/vdso/vsgx_enter_enclave.S
> > > > >>> new file mode 100644
> > > > >>> index 000000000000..adbd59d41517
> > > > >>> --- /dev/null
> > > > >>> +++ b/arch/x86/entry/vdso/vsgx_enter_enclave.S
> > > > >>> @@ -0,0 +1,157 @@
> > > > >>> +SYM_FUNC_START(__vdso_sgx_enter_enclave)
> > > > >>> <snip>
> > > > >>> +.Lretpoline:
> > > > >>> + call 2f
> > > > >>> +1: pause
> > > > >>> + lfence
> > > > >>> + jmp 1b
> > > > >>> +2: mov %rax, (%rsp)
> > > > >>> + ret
> > > > >> I hate to throw further spanners in the work, but this is not compatible
> > > > >> with CET, and the user shadow stack work in progress.
> > > > > CET goes beyond my expertise. Can you describe, at least rudimentary,
> > > > > how this code is not compatible?
> > > >
> > > > CET Shadow Stacks detect attacks which modify the return address on the
> > > > stack.
> > > >
> > > > Retpoline *is* a ROP gadget. It really does modify the return address
> > > > on the stack, even if its purpose is defensive (vs Spectre v2) rather
> > > > than malicious.
> > > >
> > > > >> Whichever of these two large series lands first is going to inflict
> > > > >> fixing this problem on the other.
> > > > >>
> > > > >> As the vdso text is global (to a first approximation), it must not be a
> > > > >> retpoline if any other process is liable to want to use CET-SS.
> > > > > Why is that?
> > > >
> > > > Because when CET-SS is enabled, the ret will suffer a #CP exception
> > > > (return address on the stack not matching the one recorded in the shadow
> > > > stack), which I presume/hope is wired into SIGSEGV.
> > > >
> > >
> > > Here is the CET compatible retpoline:
> > >
> > > endbr64
> > > /* Check if shadow stack is in use. NB: R11 is the only usable
> > > scratch register for function calls. */
> > > xorl %r11d, %r11d
> > > rdsspq %r11
> > > testq %r11, %r11
> > > jnz 3f
> > > call 2f
> > > 1:
> > > pause
> > > lfence
> > > jmp 1b
> > > 2:
> > > mov %rax, (%rsp)
> > > ret
> > > 3:
> > > /* Shadow stack is in use. Make the indirect call. */
> > > call *%rax
> > > ret
> >
> > What do we expect user programs to do on CET systems? It would be
> > nice if we could instead ALTERNATIVE this out if X86_FEATURE_SHSTK.
> >
> > --Andy
>
> I'm open to do either solution. My thinking was to initially do things
> vsgx.S local (i.e. consider ALTERNATIVE post upstreaming) and use the
> above solution but I'm also fine doing ALTERNATIVE. Dave kindly briefed
> on details how that thing works and it should be perfectly usable for
> our use case.
>
Since SHSTK and IBT are enabled per process, not the whole machine,
are you going to patch vDSO on a per-process basis?
--
H.J.
next prev parent reply other threads:[~2020-09-28 23:23 UTC|newest]
Thread overview: 183+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-15 11:28 [PATCH v38 00/24] Intel SGX foundations Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 01/24] x86/cpufeatures: x86/msr: Add Intel SGX hardware bits Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 02/24] x86/cpufeatures: x86/msr: Add Intel SGX Launch Control " Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 03/24] x86/mm: x86/sgx: Signal SIGSEGV with PF_SGX Jarkko Sakkinen
2020-09-16 11:44 ` Borislav Petkov
2020-09-16 20:30 ` Jarkko Sakkinen
2020-09-16 20:32 ` Borislav Petkov
2020-09-15 11:28 ` [PATCH v38 04/24] x86/sgx: Add SGX microarchitectural data structures Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 05/24] x86/sgx: Add wrappers for ENCLS leaf functions Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 06/24] x86/cpu/intel: Detect SGX support Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 07/24] x86/cpu/intel: Add nosgx kernel parameter Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 08/24] x86/sgx: Initialize metadata for Enclave Page Cache (EPC) sections Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 09/24] x86/sgx: Add __sgx_alloc_epc_page() and sgx_free_epc_page() Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 10/24] mm: Add vm_ops->mprotect() Jarkko Sakkinen
2020-09-18 12:44 ` Borislav Petkov
2020-09-18 15:09 ` Andy Lutomirski
2020-09-18 23:24 ` [PATCH v38 10/24] mm: Add vm_ops->mprotect()' Jarkko Sakkinen
2020-09-18 23:53 ` [PATCH v38 10/24] mm: Add vm_ops->mprotect() Sean Christopherson
2020-09-19 0:15 ` Andy Lutomirski
[not found] ` <20200922125801.GA133710@linux.intel.com>
2020-09-22 15:11 ` Dave Hansen
2020-09-23 13:30 ` Jarkko Sakkinen
2020-09-23 13:43 ` Jarkko Sakkinen
2020-09-23 14:33 ` Jarkko Sakkinen
2020-09-24 14:50 ` Dave Hansen
2020-09-24 16:27 ` Sean Christopherson
[not found] ` <20200921124946.GF6038@linux.intel.com>
2020-09-21 12:51 ` Jarkko Sakkinen
2020-09-21 13:14 ` Jarkko Sakkinen
[not found] ` <20200921165758.GA24156@linux.intel.com>
2020-09-21 21:07 ` Jarkko Sakkinen
2020-09-21 21:18 ` Sean Christopherson
2020-09-22 5:29 ` Jarkko Sakkinen
2020-09-22 5:35 ` Jarkko Sakkinen
2020-09-22 16:43 ` Sean Christopherson
2020-09-23 13:50 ` Jarkko Sakkinen
2020-09-24 19:11 ` Haitao Huang
2020-09-24 19:28 ` Sean Christopherson
2020-09-24 19:39 ` Dave Hansen
2020-09-24 20:01 ` Sean Christopherson
2020-09-24 20:10 ` Dave Hansen
2020-09-24 20:25 ` Sean Christopherson
2020-09-24 20:54 ` Dave Hansen
2020-09-24 23:05 ` Sean Christopherson
2020-09-24 23:09 ` Dave Hansen
2020-09-25 0:00 ` Sean Christopherson
2020-09-25 17:18 ` Dave Hansen
2020-09-25 19:43 ` Sean Christopherson
2020-09-25 19:53 ` Dave Hansen
2020-09-26 4:15 ` Andy Lutomirski
2020-09-28 0:53 ` Jarkko Sakkinen
2020-09-28 14:04 ` Dave Hansen
2020-09-28 16:19 ` Jarkko Sakkinen
2020-09-28 16:48 ` Dave Hansen
2020-09-28 19:32 ` Jarkko Sakkinen
2020-09-28 19:45 ` Dave Hansen
2020-09-28 20:19 ` Jarkko Sakkinen
2020-09-29 1:37 ` Andy Lutomirski
2020-09-29 4:05 ` Jarkko Sakkinen
2020-09-29 14:24 ` Dave Hansen
2020-09-30 0:20 ` Jarkko Sakkinen
2020-09-30 14:35 ` Dave Hansen
2020-09-28 20:18 ` Jarkko Sakkinen
2020-10-18 8:49 ` Dr. Greg
2020-10-19 21:31 ` Sean Christopherson
2020-10-20 10:01 ` Dr. Greg
2020-10-20 16:40 ` Sean Christopherson
2020-10-24 14:37 ` Dr. Greg
2020-10-24 15:33 ` Andy Lutomirski
2020-10-26 10:51 ` Dr. Greg
2020-10-26 22:59 ` Andy Lutomirski
2020-10-27 0:40 ` Sean Christopherson
2020-09-24 22:07 ` Jarkko Sakkinen
2020-09-24 21:58 ` Jarkko Sakkinen
2020-09-24 21:55 ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 11/24] x86/sgx: Add SGX enclave driver Jarkko Sakkinen
2020-09-21 9:30 ` Borislav Petkov
2020-09-21 12:09 ` Jarkko Sakkinen
2020-10-01 17:36 ` Sean Christopherson
2020-10-01 18:49 ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 12/24] x86/sgx: Add SGX_IOC_ENCLAVE_CREATE Jarkko Sakkinen
2020-09-21 10:03 ` Borislav Petkov
2020-09-21 12:28 ` Jarkko Sakkinen
2020-09-21 13:51 ` Borislav Petkov
2020-09-21 19:29 ` Jarkko Sakkinen
2020-10-03 0:23 ` Haitao Huang
2020-10-03 3:24 ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 13/24] x86/sgx: Add SGX_IOC_ENCLAVE_ADD_PAGES Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 14/24] x86/sgx: Add SGX_IOC_ENCLAVE_INIT Jarkko Sakkinen
2020-09-21 17:35 ` Borislav Petkov
2020-09-21 18:10 ` Sean Christopherson
2020-09-21 18:27 ` Borislav Petkov
[not found] ` <20200921191658.GA24823@linux.intel.com>
2020-09-22 8:29 ` Borislav Petkov
2020-09-22 11:50 ` Jarkko Sakkinen
2020-09-22 12:56 ` Jethro Beekman
2020-09-22 14:29 ` Borislav Petkov
2020-09-23 14:47 ` Jarkko Sakkinen
2020-09-23 15:55 ` Borislav Petkov
2020-09-24 12:23 ` Jarkko Sakkinen
2020-09-22 16:29 ` Sean Christopherson
2020-09-21 19:22 ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 15/24] x86/sgx: Enable provisioning for remote attestation Jarkko Sakkinen
2020-09-21 18:07 ` Borislav Petkov
2020-09-21 19:27 ` Jarkko Sakkinen
2020-09-21 19:41 ` Borislav Petkov
2020-09-21 21:26 ` Jarkko Sakkinen
2020-09-22 8:30 ` Borislav Petkov
2020-09-15 11:28 ` [PATCH v38 16/24] x86/sgx: Add a page reclaimer Jarkko Sakkinen
2020-09-22 10:45 ` Borislav Petkov
2020-09-22 14:03 ` Jarkko Sakkinen
2020-09-22 14:24 ` Borislav Petkov
2020-09-23 14:52 ` Jarkko Sakkinen
2020-09-29 1:14 ` Sean Christopherson
2020-09-29 3:50 ` Jarkko Sakkinen
2020-09-29 8:35 ` Sean Christopherson
2020-09-22 16:24 ` Sean Christopherson
2020-09-22 18:02 ` Borislav Petkov
2020-09-23 15:25 ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 17/24] x86/sgx: ptrace() support for the SGX driver Jarkko Sakkinen
2020-09-22 15:44 ` Borislav Petkov
2020-09-23 13:20 ` Jarkko Sakkinen
2020-09-23 16:17 ` Borislav Petkov
2020-09-24 11:51 ` Jarkko Sakkinen
2020-09-24 15:57 ` Borislav Petkov
2020-09-24 20:38 ` [PATCH v38 17/24] x86/sgx: ptrace() support for the SGX driver' Jarkko Sakkinen
2020-09-24 20:40 ` Jarkko Sakkinen
2020-09-25 7:53 ` Borislav Petkov
2020-09-25 11:00 ` Jarkko Sakkinen
2020-09-25 7:51 ` Borislav Petkov
2020-09-25 11:21 ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 18/24] x86/vdso: Add support for exception fixup in vDSO functions Jarkko Sakkinen
2020-09-23 22:07 ` Borislav Petkov
2020-09-24 12:09 ` Jarkko Sakkinen
2020-09-24 16:00 ` Borislav Petkov
2020-09-24 21:07 ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 19/24] x86/fault: Add helper function to sanitize error code Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 20/24] x86/traps: Attempt to fixup exceptions in vDSO before signaling Jarkko Sakkinen
2020-09-24 16:31 ` Borislav Petkov
2020-09-24 23:11 ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 21/24] x86/vdso: Implement a vDSO for Intel SGX enclave call Jarkko Sakkinen
2020-09-24 18:04 ` Borislav Petkov
2020-09-25 1:00 ` Jarkko Sakkinen
2020-09-25 8:28 ` Borislav Petkov
2020-09-27 23:37 ` Jarkko Sakkinen
2020-09-28 8:30 ` Borislav Petkov
2020-09-28 15:02 ` Jarkko Sakkinen
2020-09-25 8:39 ` Jethro Beekman
2020-09-25 11:17 ` Jarkko Sakkinen
2020-09-25 11:43 ` Jethro Beekman
[not found] ` <20200925003808.GB20333@linux.intel.com>
2020-09-25 1:04 ` Jarkko Sakkinen
2020-09-25 8:14 ` Borislav Petkov
2020-09-25 10:59 ` Jarkko Sakkinen
2020-09-28 14:36 ` Jarkko Sakkinen
2020-09-25 18:23 ` Andrew Cooper
2020-09-28 0:58 ` Jarkko Sakkinen
2020-09-28 16:44 ` Andrew Cooper
2020-09-28 18:07 ` H.J. Lu
2020-09-28 18:12 ` Andy Lutomirski
2020-09-28 18:17 ` Dave Hansen
2020-09-28 22:07 ` Jarkko Sakkinen
2020-09-28 21:56 ` Jarkko Sakkinen
2020-09-28 22:06 ` H.J. Lu [this message]
2020-09-28 22:18 ` Dave Hansen
2020-09-28 22:41 ` Andy Lutomirski
2020-09-28 23:38 ` Andrew Cooper
2020-09-29 14:10 ` Dave Hansen
2020-09-29 15:01 ` Andrew Cooper
2020-09-28 21:41 ` Jarkko Sakkinen
2020-09-28 20:42 ` Jarkko Sakkinen
2020-09-28 23:52 ` Andrew Cooper
2020-09-30 0:52 ` Jarkko Sakkinen
2020-09-28 15:43 ` Yu, Yu-cheng
2020-09-28 15:54 ` H.J. Lu
2020-09-28 16:40 ` Yu, Yu-cheng
2020-09-28 21:36 ` Jarkko Sakkinen
2020-09-28 20:56 ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 22/24] selftests/x86: Add a selftest for SGX Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 23/24] docs: x86/sgx: Document SGX micro architecture and kernel internals Jarkko Sakkinen
2020-09-23 13:50 ` Borislav Petkov
2020-09-24 11:28 ` Jarkko Sakkinen
2020-09-24 15:54 ` Borislav Petkov
2020-09-15 11:28 ` [PATCH v38 24/24] x86/sgx: Update MAINTAINERS Jarkko Sakkinen
2020-09-25 22:37 ` Sean Christopherson
2020-09-28 0:44 ` Jarkko Sakkinen
-- strict thread matches above, loose matches on Subject: below --
2020-09-15 11:04 [PATCH v38 00/24] Intel SGX foundations Jarkko Sakkinen
2020-09-15 11:05 ` [PATCH v38 21/24] x86/vdso: Implement a vDSO for Intel SGX enclave call Jarkko Sakkinen
2020-09-28 1:32 ` Jarkko Sakkinen
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