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From: David Howells <dhowells@redhat.com>
To: Dave Jiang <dave.jiang@intel.com>
Cc: alison.schofield@intel.com, keescook@chromium.org,
	linux-nvdimm@lists.01.org, dhowells@redhat.com,
	keyrings@vger.kernel.org
Subject: Re: [PATCH v5 06/12] nfit/libnvdimm: add set passphrase support for Intel nvdimms
Date: Fri, 20 Jul 2018 16:40:03 +0100	[thread overview]
Message-ID: <9090.1532101203@warthog.procyon.org.uk> (raw)
In-Reply-To: <4d79bd7b-c992-8259-2408-100756b9983e@intel.com>

Dave Jiang <dave.jiang@intel.com> wrote:

> > Can you show me the whole file?
> https://lists.01.org/pipermail/linux-nvdimm/2018-July/016958.html

Is that exactly what's in your /etc/request-key.conf?

> > As I understand it, you poke an attribute file in sysfs by writing
> > "update" to it and this triggers a request_key() call.  The kernel then
> > links the key it found across to the internal keyring.
> 
> Correct. And when there isn't a key, it needs to fetch from userspace
> and construct the key.

I think I've missed a step.  Am I right in thinking that the "update" command
is just for changing the password, and is not the primary way that passwords
get into the kernel to, say, unlock the device?

> > You could instead require that the key be specified directly, ie. you
> > write "update <keyid>" to the attribute file.  The driver can then call
> > key_lookup() to get the key - or, better still, we should make
> > lookup_user_key() available so that you can call that - which will do a
> > security check.
> 
> I can attach the keyid to the nvdimm when I initially get a success key
> and the update can look it up easily enough. I'm not groking the
> lookup_user_key() comment. What determines a key to be a user key or a
> kernel key?

lookup_user_key() converts a key serial number into a key applies all the
security checks to make sure that userspace is allowed to use that key for
some purpose.

key_lookup(), on the other hand, has no security checks whatsoever.

So if you're using a key ID given to you by userspace, you have to use
lookup_user_key().  Whereas if you want to find a key by description - and
potentially create it - you use request_key().  request_key() also does all
the appropriate security checks.

So I would be tempted to make the update command take an explicit key ID
rather than calling request_key() - particularly as you want to control what
the password gets changed to.  Possibly even make it take *two* explicit key
IDs: the key holding the new password and the key holding the old one.  Then
you can have security checks on both and you can compare the descriptions to
make sure they're the same.

David
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  parent reply	other threads:[~2018-07-20 15:40 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-17 20:54 [PATCH v5 00/12] Adding security support for nvdimm Dave Jiang
2018-07-17 20:54 ` [PATCH v5 01/12] nfit: add support for Intel DSM 1.7 commands Dave Jiang
2018-07-18 17:02   ` Elliott, Robert (Persistent Memory)
2018-07-17 20:54 ` [PATCH v5 02/12] libnvdimm: create keyring to store security keys Dave Jiang
2018-07-17 23:56   ` Eric Biggers
2018-07-17 20:54 ` [PATCH v5 03/12] nfit/libnvdimm: store dimm id as a member to struct nvdimm Dave Jiang
2018-07-18 15:40   ` Elliott, Robert (Persistent Memory)
2018-07-18 15:49     ` Dave Jiang
2018-07-17 20:54 ` [PATCH v5 04/12] nfit/libnvdimm: add unlock of nvdimm support for Intel DIMMs Dave Jiang
2018-07-18  0:00   ` Eric Biggers
2018-07-17 20:54 ` [PATCH v5 05/12] keys: add call key_put_sync() to flush key_gc_work when doing a key_put() Dave Jiang
2018-07-17 23:53   ` Eric Biggers
2018-07-17 23:58     ` Dave Jiang
2018-07-17 20:54 ` [PATCH v5 06/12] nfit/libnvdimm: add set passphrase support for Intel nvdimms Dave Jiang
2018-07-17 20:54 ` [PATCH v5 07/12] nfit/libnvdimm: add disable passphrase support to Intel nvdimm Dave Jiang
2018-07-17 20:54 ` [PATCH v5 08/12] nfit/libnvdimm: add freeze security " Dave Jiang
2018-07-17 20:54 ` [PATCH v5 09/12] nfit/libnvdimm: add support for issue secure erase DSM " Dave Jiang
2018-07-18 17:27   ` Elliott, Robert (Persistent Memory)
2018-07-18 17:41     ` Dave Jiang
2018-07-19  1:43       ` Elliott, Robert (Persistent Memory)
2018-07-19  6:09         ` Li, Juston
2018-07-19 20:06         ` Dave Jiang
2018-07-17 20:55 ` [PATCH v5 10/12] nfit_test: add context to dimm_dev for nfit_test Dave Jiang
2018-07-17 20:55 ` [PATCH v5 11/12] nfit_test: add test support for Intel nvdimm security DSMs Dave Jiang
2018-07-17 20:55 ` [PATCH v5 12/12] libnvdimm: add documentation for nvdimm security support Dave Jiang
2018-07-17 23:26 ` [PATCH v5 00/12] Adding security support for nvdimm Eric Biggers
2018-07-17 23:37   ` Dave Jiang
2018-07-18 10:40 ` [PATCH v5 05/12] keys: add call key_put_sync() to flush key_gc_work when doing a key_put() David Howells
2018-07-18 10:50 ` [PATCH v5 02/12] libnvdimm: create keyring to store security keys David Howells
2018-07-18 19:40   ` Dave Jiang
2018-07-18 20:38   ` David Howells
2018-07-18 11:14 ` [PATCH v5 06/12] nfit/libnvdimm: add set passphrase support for Intel nvdimms David Howells
2018-07-18 16:05   ` Dave Jiang
2018-07-18 19:47     ` Dave Jiang
2018-07-18 20:41     ` David Howells
2018-07-18 20:47       ` Dave Jiang
2018-07-19  0:28   ` Dave Jiang
2018-07-19  8:22   ` David Howells
2018-07-19 21:28     ` Dave Jiang
2018-07-20  0:04       ` Dave Jiang
2018-07-20 15:40     ` David Howells [this message]
2018-07-20 16:40       ` Dave Jiang
2018-08-02 11:07       ` David Howells
2018-07-18 11:17 ` [PATCH v5 05/12] keys: add call key_put_sync() to flush key_gc_work when doing a key_put() David Howells
2018-07-18 11:20 ` [PATCH v5 06/12] nfit/libnvdimm: add set passphrase support for Intel nvdimms David Howells

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