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From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Andy Lutomirski <luto@kernel.org>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>,
	Cedric Xing <cedric.xing@intel.com>,
	Stephen Smalley <sds@tycho.nsa.gov>,
	James Morris <jmorris@namei.org>,
	"Serge E . Hallyn" <serge@hallyn.com>,
	LSM List <linux-security-module@vger.kernel.org>,
	Paul Moore <paul@paul-moore.com>,
	Eric Paris <eparis@parisplace.org>,
	selinux@vger.kernel.org, Jethro Beekman <jethro@fortanix.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	LKML <linux-kernel@vger.kernel.org>, X86 ML <x86@kernel.org>,
	linux-sgx@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	nhorman@redhat.com, npmccallum@redhat.com,
	Serge Ayoun <serge.ayoun@intel.com>,
	Shay Katz-zamir <shay.katz-zamir@intel.com>,
	Haitao Huang <haitao.huang@intel.com>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Kai Svahn <kai.svahn@intel.com>, Borislav Petkov <bp@alien8.de>,
	Josh Triplett <josh@joshtriplett.org>,
	Kai Huang <kai.huang@intel.com>,
	David Rientjes <rientjes@google.com>,
	William Roberts <william.c.roberts@intel.com>,
	Philip Tricca <philip.b.tricca@intel.com>
Subject: Re: [RFC PATCH 2/9] x86/sgx: Do not naturally align MAP_FIXED address
Date: Wed, 5 Jun 2019 18:15:24 +0300	[thread overview]
Message-ID: <20190605151524.GJ11331@linux.intel.com> (raw)
In-Reply-To: <CALCETrVe0jhAWAFmx+NFEjJcijSJv2LDVC7cUXi0w99kNKjh_g@mail.gmail.com>

On Tue, Jun 04, 2019 at 01:16:04PM -0700, Andy Lutomirski wrote:
> On Tue, Jun 4, 2019 at 4:50 AM Jarkko Sakkinen
> <jarkko.sakkinen@linux.intel.com> wrote:
> >
> > On Fri, May 31, 2019 at 04:31:52PM -0700, Sean Christopherson wrote:
> > > SGX enclaves have an associated Enclave Linear Range (ELRANGE) that is
> > > tracked and enforced by the CPU using a base+mask approach, similar to
> > > how hardware range registers such as the variable MTRRs.  As a result,
> > > the ELRANGE must be naturally sized and aligned.
> > >
> > > To reduce boilerplate code that would be needed in every userspace
> > > enclave loader, the SGX driver naturally aligns the mmap() address and
> > > also requires the range to be naturally sized.  Unfortunately, SGX fails
> > > to grant a waiver to the MAP_FIXED case, e.g. incorrectly rejects mmap()
> > > if userspace is attempting to map a small slice of an existing enclave.
> > >
> > > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> >
> > Why you want to allow mmap() to be called multiple times? mmap() could
> > be allowed only once with PROT_NONE and denied afterwards. Is this for
> > sending fd to another process that would map already existing enclave?
> >
> > I don't see any checks for whether the is enclave underneath. Also, I
> > think that in all cases mmap() callback should allow only PROT_NONE
> > as permissions for clarity even if it could called multiple times.
> >
> 
> What's the advantage to only allowing PROT_NONE?  The idea here is to
> allow a PROT_NONE map followed by some replacemets that overlay it for
> the individual segments.  Admittedly, mprotect() can do the same
> thing, but disallowing mmap() seems at least a bit surprising.

I was merely wondering if it is specifically for the application where a
client process would mmap(MAP_FIXED) an enclave created by a server
process.

/Jarkko

  parent reply	other threads:[~2019-06-05 15:15 UTC|newest]

Thread overview: 77+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-31 23:31 [RFC PATCH 0/9] security: x86/sgx: SGX vs. LSM Sean Christopherson
2019-05-31 23:31 ` [RFC PATCH 1/9] x86/sgx: Remove unused local variable in sgx_encl_release() Sean Christopherson
2019-06-04 11:41   ` Jarkko Sakkinen
2019-05-31 23:31 ` [RFC PATCH 2/9] x86/sgx: Do not naturally align MAP_FIXED address Sean Christopherson
2019-06-04 11:49   ` Jarkko Sakkinen
2019-06-04 20:16     ` Andy Lutomirski
2019-06-04 22:10       ` Xing, Cedric
2019-06-05 14:08         ` Sean Christopherson
2019-06-05 15:17         ` Jarkko Sakkinen
2019-06-05 20:14           ` Andy Lutomirski
2019-06-06 15:37             ` Jarkko Sakkinen
2019-06-13 13:48               ` Jarkko Sakkinen
2019-06-13 16:47                 ` Xing, Cedric
2019-06-13 17:14                   ` Sean Christopherson
2019-06-14 15:18                     ` Jarkko Sakkinen
2019-06-05 15:15       ` Jarkko Sakkinen [this message]
2019-05-31 23:31 ` [RFC PATCH 3/9] x86/sgx: Allow userspace to add multiple pages in single ioctl() Sean Christopherson
2019-06-03  6:26   ` Xing, Cedric
2019-06-03 20:08     ` Sean Christopherson
2019-06-03 20:39       ` Sean Christopherson
2019-06-03 23:45         ` Xing, Cedric
2019-06-04  0:54           ` Sean Christopherson
2019-06-04 20:18         ` Andy Lutomirski
2019-06-04 22:02           ` Xing, Cedric
2019-06-03 20:14   ` Dave Hansen
2019-06-03 20:37     ` Sean Christopherson
2019-06-03 20:39       ` Dave Hansen
2019-06-03 23:48       ` Xing, Cedric
2019-06-04  0:55         ` Sean Christopherson
2019-06-04 11:55   ` Jarkko Sakkinen
2019-05-31 23:31 ` [RFC PATCH 4/9] mm: Introduce vm_ops->mprotect() Sean Christopherson
2019-06-03  6:27   ` Xing, Cedric
2019-06-04 12:24   ` Jarkko Sakkinen
2019-06-04 14:51   ` Andy Lutomirski
2019-05-31 23:31 ` [RFC PATCH 5/9] x86/sgx: Restrict mapping without an enclave page to PROT_NONE Sean Christopherson
2019-06-03  6:28   ` Xing, Cedric
2019-06-04 15:32   ` Jarkko Sakkinen
2019-05-31 23:31 ` [RFC PATCH 6/9] x86/sgx: Require userspace to provide allowed prots to ADD_PAGES Sean Christopherson
2019-06-03  6:28   ` Xing, Cedric
2019-06-04 16:23   ` Jarkko Sakkinen
2019-06-04 16:45     ` Sean Christopherson
2019-06-05 15:06       ` Jarkko Sakkinen
2019-06-04 20:23   ` Andy Lutomirski
2019-06-05 11:10   ` Ayoun, Serge
2019-06-05 23:58     ` Sean Christopherson
2019-05-31 23:31 ` [RFC PATCH 7/9] x86/sgx: Enforce noexec filesystem restriction for enclaves Sean Christopherson
2019-06-03  6:29   ` Xing, Cedric
2019-06-04 20:26     ` Andy Lutomirski
2019-06-04 16:25   ` Jarkko Sakkinen
2019-06-04 20:25     ` Andy Lutomirski
2019-06-04 20:34       ` Sean Christopherson
2019-06-04 21:54       ` Xing, Cedric
2019-06-05 15:10       ` Jarkko Sakkinen
2019-06-06  1:01         ` Sean Christopherson
2019-05-31 23:31 ` [RFC PATCH 8/9] LSM: x86/sgx: Introduce ->enclave_load() hook for Intel SGX Sean Christopherson
2019-06-03  6:28   ` Xing, Cedric
2019-06-03 14:19   ` Stephen Smalley
2019-06-03 14:42     ` Sean Christopherson
2019-06-03 18:38       ` Stephen Smalley
2019-06-03 18:45         ` Dave Hansen
2019-06-04 20:29   ` Andy Lutomirski
2019-06-04 20:36     ` Sean Christopherson
2019-06-04 21:43       ` Xing, Cedric
2019-06-06  2:04         ` Sean Christopherson
2019-05-31 23:31 ` [RFC PATCH 9/9] security/selinux: Add enclave_load() implementation Sean Christopherson
2019-06-03 15:01   ` Stephen Smalley
2019-06-03 15:50     ` Sean Christopherson
2019-06-02  7:29 ` [RFC PATCH 0/9] security: x86/sgx: SGX vs. LSM Xing, Cedric
2019-06-03 17:15   ` Sean Christopherson
2019-06-03 18:30     ` Xing, Cedric
2019-06-04  1:36       ` Sean Christopherson
2019-06-04 15:33       ` Stephen Smalley
2019-06-04 16:30         ` Sean Christopherson
2019-06-04 21:38         ` Xing, Cedric
2019-06-03 17:47   ` Stephen Smalley
2019-06-03 18:02     ` Xing, Cedric
2019-06-04 11:15 ` Jarkko Sakkinen

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