From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Borislav Petkov <bp@alien8.de>,
x86@kernel.org, linux-sgx@vger.kernel.org,
linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org,
Jethro Beekman <jethro@fortanix.com>,
Haitao Huang <haitao.huang@linux.intel.com>,
Chunyang Hui <sanqian.hcy@antfin.com>,
Jordan Hand <jorhand@linux.microsoft.com>,
Nathaniel McCallum <npmccallum@redhat.com>,
Seth Moore <sethmo@google.com>,
Suresh Siddha <suresh.b.siddha@intel.com>,
akpm@linux-foundation.org, andriy.shevchenko@linux.intel.com,
asapek@google.com, cedric.xing@intel.com,
chenalexchen@google.com, conradparker@google.com,
cyhanish@google.com, dave.hansen@intel.com,
haitao.huang@intel.com, josh@joshtriplett.org,
kai.huang@intel.com, kai.svahn@intel.com, kmoy@google.com,
ludloff@google.com, luto@kernel.org, nhorman@redhat.com,
puiterwijk@redhat.com, rientjes@google.com, tglx@linutronix.de,
yaozhangx@google.com
Subject: Re: [PATCH v33 11/21] x86/sgx: Linux Enclave Driver
Date: Tue, 7 Jul 2020 06:29:45 +0300 [thread overview]
Message-ID: <20200707032945.GA127977@linux.intel.com> (raw)
In-Reply-To: <20200707013847.GA5208@linux.intel.com>
On Mon, Jul 06, 2020 at 06:38:47PM -0700, Sean Christopherson wrote:
> On Sat, Jul 04, 2020 at 04:43:49AM +0300, Jarkko Sakkinen wrote:
> > On Mon, Jun 29, 2020 at 08:27:19AM -0700, Sean Christopherson wrote:
> > > On Sat, Jun 27, 2020 at 07:43:35PM +0200, Borislav Petkov wrote:
> > > > And you could do similar sanity checks in the other ioctl functions.
> > >
> > > Ya, as above, SGX_ENCL_INITIALIZED can be checked here.
> > >
> > > SGX_ENCL_DEAD is actually already checked in in the top level sgx_ioctl(),
> > > i.e. the check in sgx_encl_add_page() can technically be flat out dropped.
> > >
> > > I say "technically" because I'm a bit torn over SGX_ENCL_DEAD; encl->lock
> > > must be held to SGX_ENCL_DEAD (the page fault and reclaim flows rely on
> > > this), but as it stands today only ioctl() paths (guarded by SGX_ENCL_IOCTL)
> > > and sgx_release() (makes the ioctls() unreachable) set SGX_ENCL_DEAD.
> > >
> > > So it's safe to check SGX_ENCL_DEAD from ioctl() context without holding
> > > encl->lock, at least in the current code base, but it feels weird/sketchy.
> > >
> > > In the end I don't think I have a strong opinion. Removing the technically
> > > unnecessary DEAD check in sgx_encl_add_page() is the simplest change, so it
> > > may make sense to do that and nothing more for initial upstreaming. Long
> > > term, I fully expect we'll add paths that set SGX_ENCL_DEAD outside of
> > > ioctl() context, e.g. to handle EPC OOM, but it wouldn't be a bad thing to
> > > have a standalone commit in a future series to add DEAD checks (under
> > > encl->lock) in the ADD and INIT flows.
> >
> > AFAIK nonne of th ioctl's should not need SGX_ENCL_DEAD check.
>
> I can't tell if the double negative was intended, but I took a peek at your
> current master and see that you removed the SGX_ENCL_DEAD check in
> sgx_ioctl(). That check needs to stay, e.g. if EEXTEND fails we absolutely
> need to prevent any further operations on the enclave.
>
> The above was calling out that additional checks on SGX_ENCL_DEAD after
> acquiring encl->lock are not necessary because SGX_ENCL_DEAD can only be
> set when the ioctls() are no longer reachable or from within an ioctl(),
> which provides exclusivity via SGX_ENCL_IOCTL.
Got it.
/Jarkko
next prev parent reply other threads:[~2020-07-07 3:30 UTC|newest]
Thread overview: 93+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-17 22:08 [PATCH v33 00/21] Intel SGX foundations Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 01/21] x86/cpufeatures: x86/msr: Add Intel SGX hardware bits Jarkko Sakkinen
2020-06-22 17:37 ` Borislav Petkov
2020-06-25 1:25 ` Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 02/21] x86/cpufeatures: x86/msr: Add Intel SGX Launch Control " Jarkko Sakkinen
2020-06-24 13:04 ` Borislav Petkov
2020-06-24 14:34 ` Sean Christopherson
2020-06-25 1:28 ` Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 03/21] x86/mm: x86/sgx: Signal SIGSEGV with PF_SGX Jarkko Sakkinen
2020-06-25 8:59 ` Borislav Petkov
2020-06-25 15:34 ` Sean Christopherson
2020-06-25 16:49 ` Borislav Petkov
2020-06-25 20:52 ` Jarkko Sakkinen
2020-06-25 21:11 ` Borislav Petkov
2020-06-26 13:34 ` Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 04/21] x86/sgx: Add SGX microarchitectural data structures Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 05/21] x86/sgx: Add wrappers for ENCLS leaf functions Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 06/21] x86/cpu/intel: Detect SGX support Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 07/21] x86/cpu/intel: Add nosgx kernel parameter Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 08/21] x86/sgx: Initialize metadata for Enclave Page Cache (EPC) sections Jarkko Sakkinen
2020-06-25 10:14 ` Borislav Petkov
2020-06-25 20:11 ` Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 09/21] x86/sgx: Add __sgx_alloc_epc_page() and sgx_free_epc_page() Jarkko Sakkinen
2020-06-25 17:06 ` Borislav Petkov
2020-06-25 20:55 ` Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 10/21] mm: Introduce vm_ops->may_mprotect() Jarkko Sakkinen
2020-06-25 17:14 ` Borislav Petkov
2020-06-25 17:30 ` Matthew Wilcox
2020-06-25 18:06 ` Sean Christopherson
2020-06-25 22:40 ` Jarkko Sakkinen
2020-06-25 22:26 ` Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 11/21] x86/sgx: Linux Enclave Driver Jarkko Sakkinen
2020-06-25 17:23 ` Borislav Petkov
2020-06-25 18:34 ` Sean Christopherson
2020-06-25 18:45 ` Borislav Petkov
2020-06-26 14:19 ` Jarkko Sakkinen
2020-06-25 20:21 ` Jarkko Sakkinen
2020-06-25 20:25 ` Borislav Petkov
2020-06-26 13:40 ` Jarkko Sakkinen
2020-06-25 18:53 ` Borislav Petkov
2020-06-26 14:17 ` Jarkko Sakkinen
2020-06-26 9:14 ` Borislav Petkov
2020-06-26 14:16 ` Sean Christopherson
2020-06-26 14:20 ` Borislav Petkov
2020-07-03 23:04 ` Jarkko Sakkinen
2020-07-03 3:09 ` Jarkko Sakkinen
2020-06-26 15:34 ` Borislav Petkov
2020-07-04 0:13 ` Jarkko Sakkinen
2020-10-26 21:26 ` Dave Hansen
2020-10-27 1:52 ` Jarkko Sakkinen
2020-10-27 10:05 ` Borislav Petkov
2020-10-27 15:20 ` Dave Hansen
2020-10-27 15:37 ` Borislav Petkov
2020-06-27 17:43 ` Borislav Petkov
2020-06-29 15:27 ` Sean Christopherson
2020-06-29 15:37 ` Borislav Petkov
2020-07-04 1:43 ` Jarkko Sakkinen
2020-07-07 1:38 ` Sean Christopherson
2020-07-07 3:29 ` Jarkko Sakkinen [this message]
2020-07-04 1:42 ` Jarkko Sakkinen
2020-07-02 3:59 ` Sean Christopherson
2020-07-04 3:31 ` Jarkko Sakkinen
2020-09-02 3:06 ` Haitao Huang
2020-09-02 16:10 ` Sean Christopherson
2020-09-02 18:40 ` Haitao Huang
2020-09-04 12:01 ` Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 12/21] x86/sgx: Allow a limited use of ATTRIBUTE.PROVISIONKEY for attestation Jarkko Sakkinen
2020-06-29 16:02 ` Borislav Petkov
2020-06-29 22:04 ` Sean Christopherson
2020-06-30 8:49 ` Borislav Petkov
2020-06-30 14:20 ` Sean Christopherson
2020-06-30 17:13 ` Andy Lutomirski
2020-07-02 20:47 ` Dr. Greg
2020-07-03 2:43 ` Jarkko Sakkinen
2020-07-03 2:38 ` Jarkko Sakkinen
2020-07-03 2:32 ` Jarkko Sakkinen
2020-07-03 2:55 ` Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 13/21] x86/sgx: Add a page reclaimer Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 14/21] x86/sgx: ptrace() support for the SGX driver Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 15/21] x86/vdso: Add support for exception fixup in vDSO functions Jarkko Sakkinen
2020-06-29 17:10 ` Borislav Petkov
2020-06-30 6:00 ` Sean Christopherson
2020-06-30 8:41 ` Borislav Petkov
2020-06-30 14:55 ` Sean Christopherson
2020-06-30 16:48 ` Andy Lutomirski
2020-06-30 17:23 ` Sean Christopherson
2020-07-02 12:52 ` Thomas Gleixner
2020-06-17 22:08 ` [PATCH v33 16/21] x86/fault: Add helper function to sanitize error code Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 17/21] x86/traps: Attempt to fixup exceptions in vDSO before signaling Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 18/21] x86/vdso: Implement a vDSO for Intel SGX enclave call Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 19/21] selftests/x86: Add a selftest for SGX Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 20/21] docs: x86/sgx: Document SGX micro architecture and kernel internals Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 21/21] x86/sgx: Update MAINTAINERS Jarkko Sakkinen
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