From: Jethro Beekman <jethro@fortanix.com>
To: "Xing, Cedric" <cedric.xing@intel.com>,
Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"x86@kernel.org" <x86@kernel.org>,
"linux-sgx@vger.kernel.org" <linux-sgx@vger.kernel.org>
Cc: "akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"Hansen, Dave" <dave.hansen@intel.com>,
"Christopherson, Sean J" <sean.j.christopherson@intel.com>,
"nhorman@redhat.com" <nhorman@redhat.com>,
"npmccallum@redhat.com" <npmccallum@redhat.com>,
"Ayoun, Serge" <serge.ayoun@intel.com>,
"Katz-zamir, Shay" <shay.katz-zamir@intel.com>,
"Huang, Haitao" <haitao.huang@intel.com>,
"andriy.shevchenko@linux.intel.com"
<andriy.shevchenko@linux.intel.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"Svahn, Kai" <kai.svahn@intel.com>, "bp@alien8.de" <bp@alien8.de>,
"josh@joshtriplett.org" <josh@joshtriplett.org>,
"luto@kernel.org" <luto@kernel.org>,
"Huang, Kai" <kai.huang@intel.com>,
"rientjes@google.com" <rientjes@google.com>,
Andy Lutomirski <luto@amacapital.net>,
Dave Hansen <dave.hansen@linux.intel.com>,
Haitao Huang <haitao.huang@linux.intel.com>,
"Dr . Greg Wettstein" <greg@enjellic.com>
Subject: Re: [PATCH v19,RESEND 24/27] x86/vdso: Add __vdso_sgx_enter_enclave() to wrap SGX enclave transitions
Date: Wed, 20 Mar 2019 19:02:06 +0000 [thread overview]
Message-ID: <c7da5f00-f266-48a7-2149-49d7c8ba44a5@fortanix.com> (raw)
In-Reply-To: <960B34DE67B9E140824F1DCDEC400C0F4E85C484@ORSMSX116.amr.corp.intel.com>
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On 2019-03-20 11:30, Xing, Cedric wrote:
>> +/**
>> + * __vdso_sgx_enter_enclave() - Enter an SGX enclave
>> + *
>> + * %eax: ENCLU leaf, must be EENTER or ERESUME
>> + * %rbx: TCS, must be non-NULL
>> + * %rcx: Optional pointer to 'struct sgx_enclave_exception'
>> + *
>> + * Return:
>> + * 0 on a clean entry/exit to/from the enclave
>> + * -EINVAL if ENCLU leaf is not allowed or if TCS is NULL
>> + * -EFAULT if ENCLU or the enclave faults
>> + *
>> + * Note that __vdso_sgx_enter_enclave() is not compliant with the x86-
>> 64 ABI.
>> + * All registers except RSP must be treated as volatile from the
>> +caller's
>> + * perspective, including but not limited to GPRs, EFLAGS.DF, MXCSR,
>> FCW, etc...
>> + * Conversely, the enclave being run must preserve the untrusted RSP
>> and stack.
>
> By requiring preservation of RSP at both AEX and EEXIT, this precludes the possibility of using the untrusted stack as temporary storage by enclaves. While that looks reasonable at first glance, I'm afraid it isn't the case in reality. The untrusted stack is inarguably the most convenient way for data exchange between an enclave and its enclosing process, and is in fact being used for that purpose by almost all existing enclaves to date. Given the expectation that this API will be used by all future SGX application, it looks unwise to ban the most convenient and commonly used approach for data exchange.
For reference, here's the code in the Intel toolchain responsible for
this:
https://github.com/intel/linux-sgx/blob/6a0b5ac71f8d16f04e0376f3b2168e80c773dd23/sdk/trts/trts.cpp#L125-L140
Regarding "almost all existing enclaves to date", enclaves built with
the Fortanix toolchain don't touch the untrusted stack.
--
Jethro Beekman | Fortanix
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next prev parent reply other threads:[~2019-03-20 19:02 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-20 16:20 [PATCH v19,RESEND 00/27] Intel SGX1 support Jarkko Sakkinen
2019-03-20 16:20 ` [PATCH v19,RESEND 01/27] x86/cpufeatures: Add Intel-defined SGX feature bit Jarkko Sakkinen
2019-03-20 19:41 ` Neil Horman
2019-03-21 14:16 ` Jarkko Sakkinen
2019-03-20 16:20 ` [PATCH v19,RESEND 02/27] x86/cpufeatures: Add SGX sub-features (as Linux-defined bits) Jarkko Sakkinen
2019-03-20 16:20 ` [PATCH v19,RESEND 03/27] x86/msr: Add IA32_FEATURE_CONTROL.SGX_ENABLE definition Jarkko Sakkinen
2019-03-20 16:20 ` [PATCH v19,RESEND 04/27] x86/cpufeatures: Add Intel-defined SGX_LC feature bit Jarkko Sakkinen
2019-03-20 16:20 ` [PATCH v19,RESEND 05/27] x86/msr: Add SGX Launch Control MSR definitions Jarkko Sakkinen
2019-03-20 16:20 ` [PATCH v19,RESEND 06/27] x86/mm: x86/sgx: Add new 'PF_SGX' page fault error code bit Jarkko Sakkinen
2019-03-20 16:20 ` [PATCH v19,RESEND 07/27] x86/mm: x86/sgx: Signal SIGSEGV for userspace #PFs w/ PF_SGX Jarkko Sakkinen
2019-03-20 16:21 ` [PATCH v19,RESEND 08/27] x86/cpu/intel: Detect SGX support and update caps appropriately Jarkko Sakkinen
2019-03-26 12:17 ` Huang, Kai
2019-03-26 14:27 ` Sean Christopherson
2019-03-26 21:25 ` Huang, Kai
2019-03-26 21:57 ` Sean Christopherson
2019-03-26 23:19 ` Huang, Kai
2019-03-20 16:21 ` [PATCH v19,RESEND 09/27] x86/sgx: Add ENCLS architectural error codes Jarkko Sakkinen
2019-03-20 16:21 ` [PATCH v19,RESEND 10/27] x86/sgx: Add SGX1 and SGX2 architectural data structures Jarkko Sakkinen
2019-03-20 16:21 ` [PATCH v19,RESEND 11/27] x86/sgx: Add definitions for SGX's CPUID leaf and variable sub-leafs Jarkko Sakkinen
2019-03-20 16:21 ` [PATCH v19,RESEND 12/27] x86/sgx: Enumerate and track EPC sections Jarkko Sakkinen
2019-03-20 16:21 ` [PATCH v19,RESEND 13/27] x86/sgx: Add wrappers for ENCLS leaf functions Jarkko Sakkinen
2019-03-20 16:21 ` [PATCH v19,RESEND 14/27] x86/sgx: Add functions to allocate and free EPC pages Jarkko Sakkinen
2019-03-20 16:21 ` [PATCH v19,RESEND 15/27] x86/sgx: Add sgx_einit() for initializing enclaves Jarkko Sakkinen
2019-03-20 16:21 ` [PATCH v19,RESEND 16/27] x86/sgx: Add the Linux SGX Enclave Driver Jarkko Sakkinen
2019-03-26 12:01 ` Huang, Kai
2019-03-26 12:40 ` Thomas Gleixner
2019-03-26 14:54 ` Sean Christopherson
2019-03-26 21:11 ` Huang, Kai
2019-03-27 5:02 ` Jarkko Sakkinen
2019-03-20 16:21 ` [PATCH v19,RESEND 17/27] x86/sgx: Add provisioning Jarkko Sakkinen
2019-03-20 16:21 ` [PATCH v19,RESEND 18/27] x86/sgx: Add swapping code to the core and SGX driver Jarkko Sakkinen
2019-03-20 16:21 ` [PATCH v19,RESEND 19/27] x86/sgx: ptrace() support for the " Jarkko Sakkinen
2019-03-20 16:21 ` [PATCH v19,RESEND 20/27] x86/vdso: Add support for exception fixup in vDSO functions Jarkko Sakkinen
2019-03-20 16:21 ` [PATCH v19,RESEND 21/27] x86/fault: Add helper function to sanitize error code Jarkko Sakkinen
2019-03-20 16:21 ` [PATCH v19,RESEND 22/27] x86/fault: Attempt to fixup unhandled #PF in vDSO before signaling Jarkko Sakkinen
2019-03-20 16:21 ` [PATCH v19,RESEND 23/27] x86/traps: Attempt to fixup exceptions " Jarkko Sakkinen
2019-03-20 16:21 ` [PATCH v19,RESEND 24/27] x86/vdso: Add __vdso_sgx_enter_enclave() to wrap SGX enclave transitions Jarkko Sakkinen
2019-03-20 18:30 ` Xing, Cedric
2019-03-20 18:52 ` Andy Lutomirski
2019-03-20 19:57 ` Xing, Cedric
2019-03-20 21:03 ` Sean Christopherson
2019-03-21 0:17 ` Xing, Cedric
2019-03-22 21:20 ` Sean Christopherson
2019-03-21 17:17 ` Andy Lutomirski
2019-03-22 20:31 ` Xing, Cedric
2019-03-20 19:02 ` Jethro Beekman [this message]
2019-03-20 20:10 ` Xing, Cedric
2019-03-20 19:13 ` Sean Christopherson
2019-03-20 20:38 ` Xing, Cedric
2019-03-22 21:59 ` Sean Christopherson
2019-03-23 17:36 ` Xing, Cedric
2019-03-23 21:38 ` Andy Lutomirski
2019-03-24 8:59 ` Xing, Cedric
2019-03-25 18:03 ` Sean Christopherson
2019-03-25 23:59 ` Andy Lutomirski
2019-03-26 4:53 ` Xing, Cedric
2019-03-26 17:08 ` Andy Lutomirski
2019-03-28 4:23 ` Xing, Cedric
2019-03-28 19:18 ` Andy Lutomirski
2019-03-28 23:19 ` Xing, Cedric
2019-03-29 9:48 ` Jarkko Sakkinen
2019-03-31 8:43 ` Dr. Greg
2019-04-03 23:03 ` Sean Christopherson
2019-03-25 23:54 ` Andy Lutomirski
2019-03-26 4:16 ` Xing, Cedric
2019-03-20 16:21 ` [PATCH v19,RESEND 25/27] x86/sgx: SGX documentation Jarkko Sakkinen
2019-03-20 16:21 ` [PATCH v19,RESEND 26/27] selftests/x86: Add a selftest for SGX Jarkko Sakkinen
2019-03-20 16:21 ` [PATCH v19,RESEND 27/27] x86/sgx: Update MAINTAINERS Jarkko Sakkinen
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