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From: Borislav Petkov <bp@alien8.de>
To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
	linux-sgx@vger.kernel.org, akpm@linux-foundation.org,
	dave.hansen@intel.com, sean.j.christopherson@intel.com,
	nhorman@redhat.com, npmccallum@redhat.com, serge.ayoun@intel.com,
	shay.katz-zamir@intel.com, haitao.huang@intel.com,
	andriy.shevchenko@linux.intel.com, tglx@linutronix.de,
	kai.svahn@intel.com, josh@joshtriplett.org, luto@kernel.org,
	kai.huang@intel.com, rientjes@google.com, cedric.xing@intel.com
Subject: Re: [PATCH v22 10/24] x86/sgx: Add sgx_einit() for wrapping ENCLS[EINIT]
Date: Tue, 8 Oct 2019 19:30:35 +0200
Message-ID: <20191008173035.GK14765@zn.tnic> (raw)
In-Reply-To: <20190903142655.21943-11-jarkko.sakkinen@linux.intel.com>

On Tue, Sep 03, 2019 at 05:26:41PM +0300, Jarkko Sakkinen wrote:
> From: Sean Christopherson <sean.j.christopherson@intel.com>
> 
> Enclaves are SGX hosted measured and signed software entities. ENCLS[EINIT]

		SGX-hosted, measured, and ...

> leaf function checks that the enclave has a legit signed measurement and
> transforms the enclave to the state ready for execution. The signed
> measurement is provided by the caller in the form of SIGSTRUCT data
> structure [1].
> 
> Wrap ENCLS[EINIT] into sgx_einit(). Set MSR_IA32_SGXLEPUBKEYHASH* MSRs to
> match the public key contained in the SIGSTRUCT [2]. This sets Linux to
> enforce a policy where the provided public key is as long as the signed
> measurement matches the enclave contents in memory.

That subclause needs to be separated, maybe:

  ... the provided public key is - as long as the signed measurement
  matches the the enclave contents - in memory.

Provided you mean that, of course.

> Add a per-cpu cache to avoid unnecessary reads and write to the MSRs

reads and writes?

> as they are expensive operations.
> 
> [1] Intel SDM: 37.1.3 ENCLAVE SIGNATURE STRUCTURE (SIGSTRUCT)
> [2] Intel SDM: 38.1.4 Intel SGX Launch Control Configuration
> 
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Co-developed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> ---
>  arch/x86/kernel/cpu/sgx/main.c | 51 ++++++++++++++++++++++++++++++++++
>  arch/x86/kernel/cpu/sgx/sgx.h  |  2 ++
>  2 files changed, 53 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
> index 6b4727df72ca..d3ed742e90fe 100644
> --- a/arch/x86/kernel/cpu/sgx/main.c
> +++ b/arch/x86/kernel/cpu/sgx/main.c
> @@ -17,6 +17,9 @@ EXPORT_SYMBOL_GPL(sgx_epc_sections);
>  
>  int sgx_nr_epc_sections;
>  
> +/* A per-cpu cache for the last known values of IA32_SGXLEPUBKEYHASHx MSRs. */
> +static DEFINE_PER_CPU(u64 [4], sgx_lepubkeyhash_cache);
> +
>  static struct sgx_epc_page *sgx_section_get_page(
>  	struct sgx_epc_section *section)
>  {
> @@ -106,6 +109,54 @@ void sgx_free_page(struct sgx_epc_page *page)
>  }
>  EXPORT_SYMBOL_GPL(sgx_free_page);
>  
> +static void sgx_update_lepubkeyhash_msrs(u64 *lepubkeyhash, bool enforce)
> +{
> +	u64 *cache;
> +	int i;
> +
> +	cache = per_cpu(sgx_lepubkeyhash_cache, smp_processor_id());
> +	for (i = 0; i < 4; i++) {
> +		if (enforce || (lepubkeyhash[i] != cache[i])) {
> +			wrmsrl(MSR_IA32_SGXLEPUBKEYHASH0 + i, lepubkeyhash[i]);
> +			cache[i] = lepubkeyhash[i];
> +		}
> +	}
> +}
> +
> +/**
> + * sgx_einit - initialize an enclave
> + * @sigstruct:		a pointer a SIGSTRUCT
> + * @token:		a pointer an EINITTOKEN (optional)
> + * @secs:		a pointer a SECS

That's a strange formulation "a pointer a/an" ? "to" missing?

> + * @lepubkeyhash:	the desired value for IA32_SGXLEPUBKEYHASHx MSRs
> + *
> + * Execute ENCLS[EINIT], writing the IA32_SGXLEPUBKEYHASHx MSRs according
> + * to @lepubkeyhash (if possible and necessary).
> + *
> + * Return:
> + *   0 on success,
> + *   -errno or SGX error on failure
> + */
> +int sgx_einit(struct sgx_sigstruct *sigstruct, struct sgx_einittoken *token,
> +	      struct sgx_epc_page *secs, u64 *lepubkeyhash)
> +{
> +	int ret;
> +
> +	if (!boot_cpu_has(X86_FEATURE_SGX_LC))
> +		return __einit(sigstruct, token, sgx_epc_addr(secs));
> +
> +	preempt_disable();
> +	sgx_update_lepubkeyhash_msrs(lepubkeyhash, false);
> +	ret = __einit(sigstruct, token, sgx_epc_addr(secs));
> +	if (ret == SGX_INVALID_EINITTOKEN) {
> +		sgx_update_lepubkeyhash_msrs(lepubkeyhash, true);
> +		ret = __einit(sigstruct, token, sgx_epc_addr(secs));
> +	}
> +	preempt_enable();
> +	return ret;
> +}
> +EXPORT_SYMBOL(sgx_einit);

I was about to ask why isn't this export _GPL() but it goes away in a
later patch.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

  reply index

Thread overview: 102+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-03 14:26 [PATCH v22 00/24] Intel SGX foundations Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 01/24] x86/cpufeatures: x86/msr: Add Intel SGX hardware bits Jarkko Sakkinen
2019-09-24 15:28   ` Borislav Petkov
2019-09-24 16:11     ` Sean Christopherson
2019-09-24 16:25       ` Borislav Petkov
2019-09-03 14:26 ` [PATCH v22 02/24] x86/cpufeatures: x86/msr: Intel SGX Launch Control " Jarkko Sakkinen
2019-09-24 15:52   ` Borislav Petkov
2019-09-24 20:22     ` Sean Christopherson
2019-09-25  8:51       ` Borislav Petkov
2019-09-25 17:18         ` Sean Christopherson
2019-09-25 18:31           ` Borislav Petkov
2019-09-25 19:08             ` Sean Christopherson
2019-09-27 16:11           ` Jarkko Sakkinen
2019-09-25 14:09     ` Jarkko Sakkinen
2019-09-25 14:10       ` Jarkko Sakkinen
2019-09-25 14:38         ` Jarkko Sakkinen
2019-09-25 15:19       ` Borislav Petkov
2019-09-25 16:49         ` Sean Christopherson
2019-09-25 17:28           ` Borislav Petkov
2019-09-25 18:18             ` Sean Christopherson
2019-09-03 14:26 ` [PATCH v22 03/24] x86/mm: x86/sgx: Signal SIGSEGV with PF_SGX Jarkko Sakkinen
2019-09-24 16:04   ` Borislav Petkov
2019-09-25 14:16     ` Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 04/24] x86/cpu/intel: Detect SGX supprt Jarkko Sakkinen
2019-09-24 16:13   ` Borislav Petkov
2019-09-24 17:43     ` Sean Christopherson
2019-09-24 18:21       ` Borislav Petkov
2019-09-25 14:46         ` Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 05/24] x86/sgx: Add ENCLS architectural error codes Jarkko Sakkinen
2019-09-27 10:20   ` Borislav Petkov
2019-09-27 16:08     ` Jarkko Sakkinen
2019-09-27 17:20       ` Sean Christopherson
2019-10-01 20:23         ` Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 06/24] x86/sgx: Add SGX microarchitectural data structures Jarkko Sakkinen
2019-09-27 16:27   ` Borislav Petkov
2019-10-01 19:10     ` Jarkko Sakkinen
2019-10-01 20:39     ` Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 07/24] x86/sgx: Add wrappers for ENCLS leaf functions Jarkko Sakkinen
2019-10-04  9:45   ` Borislav Petkov
2019-10-04 18:56     ` Jarkko Sakkinen
2019-10-08  4:04     ` Sean Christopherson
2019-10-08  7:18       ` Borislav Petkov
2019-10-08 13:35         ` Sean Christopherson
2019-10-08 14:56           ` Borislav Petkov
2019-09-03 14:26 ` [PATCH v22 08/24] x86/sgx: Enumerate and track EPC sections Jarkko Sakkinen
2019-10-05  9:26   ` Borislav Petkov
2019-10-07 11:58     ` Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 09/24] x86/sgx: Add functions to allocate and free EPC pages Jarkko Sakkinen
2019-10-05 16:44   ` Borislav Petkov
2019-10-07 14:50     ` Sean Christopherson
2019-10-08  9:09       ` Borislav Petkov
2019-10-08 13:31         ` Sean Christopherson
2019-10-07 17:55     ` Jarkko Sakkinen
2019-10-07 18:09       ` Borislav Petkov
2019-09-03 14:26 ` [PATCH v22 10/24] x86/sgx: Add sgx_einit() for wrapping ENCLS[EINIT] Jarkko Sakkinen
2019-10-08 17:30   ` Borislav Petkov [this message]
2019-10-08 17:45     ` Sean Christopherson
2019-10-08 17:46       ` Sean Christopherson
2019-10-08 17:53         ` Borislav Petkov
2019-09-03 14:26 ` [PATCH v22 11/24] mm: Introduce vm_ops->may_mprotect() Jarkko Sakkinen
2019-10-08 17:41   ` Borislav Petkov
2019-09-03 14:26 ` [PATCH v22 12/24] x86/sgx: Linux Enclave Driver Jarkko Sakkinen
2019-10-08 17:59   ` Borislav Petkov
2019-10-08 18:17     ` Sean Christopherson
2019-10-08 19:19       ` Borislav Petkov
2019-09-03 14:26 ` [PATCH v22 13/24] x86/sgx: Add provisioning Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 14/24] x86/sgx: Add a page reclaimer Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 15/24] x86/sgx: ptrace() support for the SGX driver Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 16/24] x86/vdso: Add support for exception fixup in vDSO functions Jarkko Sakkinen
2019-10-02 23:18   ` Jarkko Sakkinen
2019-10-02 23:45     ` Jarkko Sakkinen
2019-10-04  0:03     ` Sean Christopherson
2019-10-04 18:49       ` Jarkko Sakkinen
2019-10-04  0:15     ` Sean Christopherson
2019-10-04 18:52       ` Jarkko Sakkinen
2019-10-05 15:54         ` Sean Christopherson
2019-10-07  7:57           ` Jarkko Sakkinen
2019-10-07  8:10             ` Jarkko Sakkinen
2019-10-07 12:04               ` Jarkko Sakkinen
2019-10-08  4:54                 ` Sean Christopherson
2019-10-05 18:39         ` Sean Christopherson
2019-10-07  8:01           ` Jarkko Sakkinen
2019-10-06 23:38         ` Jarkko Sakkinen
2019-10-06 23:40           ` Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 17/24] x86/fault: Add helper function to sanitize error code Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 18/24] x86/traps: Attempt to fixup exceptions in vDSO before signaling Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 19/24] x86/vdso: Add __vdso_sgx_enter_enclave() to wrap SGX enclave transitions Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 20/24] selftests/x86: Add a selftest for SGX Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 21/24] selftests/x86: Recurse into subdirectories Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 22/24] x86/sgx: Update MAINTAINERS Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 23/24] docs: x86/sgx: Document microarchitecture Jarkko Sakkinen
2019-09-27 18:15   ` Randy Dunlap
2019-09-03 14:26 ` [PATCH v22 24/24] docs: x86/sgx: Document kernel internals Jarkko Sakkinen
2019-09-27 17:07   ` Randy Dunlap
2019-10-01 19:34     ` Jarkko Sakkinen
2019-09-13 20:38 ` [PATCH v22 00/24] Intel SGX foundations Dave Hansen
2019-09-14 13:41   ` Jarkko Sakkinen
2019-09-14 15:32     ` Dave Hansen
2019-09-16  5:23       ` Jarkko Sakkinen
2019-09-24 17:20         ` Andy Lutomirski
2019-09-25 14:32           ` Jarkko Sakkinen
2019-10-02 23:42             ` Jarkko Sakkinen

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