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From: Andy Lutomirski <luto@kernel.org>
To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: Topi Miettinen <toiwoton@gmail.com>,
	Jethro Beekman <jethro@fortanix.com>,
	Casey Schaufler <casey@schaufler-ca.com>,
	Andy Lutomirski <luto@kernel.org>,
	"Schaufler, Casey" <casey.schaufler@intel.com>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	linux-sgx@vger.kernel.org, "Svahn, Kai" <kai.svahn@intel.com>,
	"Schlobohm, Bruce" <bruce.schlobohm@intel.com>,
	Stephen Smalley <sds@tycho.nsa.gov>,
	Haitao Huang <haitao.huang@linux.intel.com>,
	Ben Hutchings <ben@decadent.org.uk>
Subject: Re: [PATCH 2/4] x86/sgx: Put enclaves into anonymous files
Date: Mon, 6 Apr 2020 16:18:20 -0700	[thread overview]
Message-ID: <CALCETrWkaUS2RU61_4KoNhn3RkW-J+SWiCQTZ623wu4b7snJ0w@mail.gmail.com> (raw)
In-Reply-To: <20200406212434.GA34134@linux.intel.com>

On Mon, Apr 6, 2020 at 2:24 PM Jarkko Sakkinen
<jarkko.sakkinen@linux.intel.com> wrote:
>
> On Mon, Apr 06, 2020 at 12:53:41PM -0700, Andy Lutomirski wrote:
> > > sgxfs is somewhat trivial to implement and has one stakeholder less to
> > > worry about. It is not really a huge stretch.
> > >
> > > Overally, I think it is something that we could live with. At least it
> > > is something that does not step on others toes.
> > >
> > > Haitao: If we go with sgxfs route, then you can for the moment do what
> > > Andy suggested: bind mount it to /dev/sgx.
> >
> > That also needs userspace support.
> >
> > I’ll start a thread on the udev list.
>
> Haven't written any code yet but just by drafting the idea I already
> pinpointed something.
>
> You would add roughly this to the existing codebase:
>
> * struct file_system_type sgxfs
> * struct fs_context_operations sgxfs_ctx_ops
> * int sgxfs_get_tree()
> * int sgxfs_fill_super()
> * const struct tree_descr sgxfs_files[]
>
> The files would be defined as like this:
>
> static const struct tree_descr sgxfs_files[] {
>         [SGXFS_ENCLAVE] = { "enclave", &sgxfs_encl_ops, /* ? */ },
>         [SGXFS_PROVISION] = { "provision", &sgxfs_encl_ops, /* ? */ },
> };
>
> The permissions would need to be completely static, which feels nasty
> from maintainability viewpoint :-( And I see no gain anywhere.
>
> In my opinion udev defining the whole /dev as noexec has zero technical
> merits. It is same as they would say that "we don't trust our own
> database". There are no real security benefits as long as dev nodes are
> configured correctly.

I tend to agree, but it could be seen as a sort-of-valid hardening measure.

I think the best bet is for you to ignore this and let userspace figure it out.

  reply	other threads:[~2020-04-06 23:18 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-31 11:44 [PATCH 0/4] Migrate enclave mapping to an anonymous inode Jarkko Sakkinen
2020-03-31 11:44 ` [PATCH 1/4] x86/sgx: Remove PROT_NONE branch from sgx_encl_may_map() Jarkko Sakkinen
2020-03-31 11:44 ` [PATCH 2/4] x86/sgx: Put enclaves into anonymous files Jarkko Sakkinen
2020-03-31 17:39   ` Andy Lutomirski
2020-04-01  0:24     ` Sean Christopherson
2020-04-02 21:41       ` Andy Lutomirski
2020-04-03  6:56         ` Jarkko Sakkinen
2020-04-03  6:59           ` Jarkko Sakkinen
2020-04-03 14:35           ` Casey Schaufler
2020-04-03 15:30             ` Jarkko Sakkinen
2020-04-03 15:50               ` Casey Schaufler
2020-04-03 22:08                 ` Jarkko Sakkinen
2020-04-04  3:54                   ` Andy Lutomirski
2020-04-04  5:46                     ` Jethro Beekman
2020-04-04  7:27                       ` Topi Miettinen
2020-04-04  9:20                         ` Jarkko Sakkinen
2020-04-06  6:42                         ` Jethro Beekman
2020-04-06 11:01                           ` Topi Miettinen
2020-04-06 16:44                             ` Andy Lutomirski
2020-04-06 17:17                               ` Jethro Beekman
2020-04-06 18:55                               ` Jarkko Sakkinen
2020-04-06 19:01                                 ` Jarkko Sakkinen
2020-04-06 19:53                                 ` Andy Lutomirski
2020-04-06 21:24                                   ` Jarkko Sakkinen
2020-04-06 23:18                                     ` Andy Lutomirski [this message]
2020-04-06 23:48                                       ` Jarkko Sakkinen
2020-04-07  7:15                                       ` Jethro Beekman
2020-04-07  8:48                                     ` Topi Miettinen
2020-04-07 16:52                                       ` Jarkko Sakkinen
2020-04-07  9:04                                     ` Topi Miettinen
2020-04-07 16:57                                       ` Jarkko Sakkinen
2020-04-07 16:59                                         ` Jarkko Sakkinen
2020-04-07 18:04                                           ` Jarkko Sakkinen
2020-04-07 19:54                                             ` Topi Miettinen
2020-04-08 13:40                                               ` Jarkko Sakkinen
2020-04-08 14:56                                                 ` Sean Christopherson
2020-04-09 18:39                                                   ` Jarkko Sakkinen
2020-04-08 21:15                                                 ` Topi Miettinen
2020-04-08 21:29                                                   ` Sean Christopherson
2020-11-19  7:23                                   ` Jethro Beekman
2020-11-19 16:09                                     ` Andy Lutomirski
2020-04-06 18:47                             ` Jarkko Sakkinen
2020-04-04  9:22                     ` Jarkko Sakkinen
2020-04-01  8:45     ` Jarkko Sakkinen
2020-03-31 11:44 ` [PATCH 3/4] x86/sgx: Move mmap() to the anonymous enclave file Jarkko Sakkinen
2020-03-31 11:44 ` [PATCH 4/4] x86/sgx: Hand over the enclave file to the user space Jarkko Sakkinen

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