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From: Matthew Garrett <mjg59@google.com>
To: Mimi Zohar <zohar@linux.ibm.com>
Cc: linux-integrity <linux-integrity@vger.kernel.org>,
	Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
	linux-fsdevel@vger.kernel.org, miklos@szeredi.hu
Subject: Re: [PATCH V2 3/4] IMA: Optionally make use of filesystem-provided hashes
Date: Mon, 4 Mar 2019 14:10:12 -0800	[thread overview]
Message-ID: <CACdnJutWRB1up6wO3aWJJah3p8k+FY6xEfjw8ETHT69Vvsz8GQ@mail.gmail.com> (raw)
In-Reply-To: <1551731553.10911.510.camel@linux.ibm.com>

On Mon, Mar 4, 2019 at 12:32 PM Mimi Zohar <zohar@linux.ibm.com> wrote:
> On Mon, 2019-03-04 at 11:52 -0800, Matthew Garrett wrote:
> > To be clear, I'm entirely happy to make this change - I'd just like to
> > ensure that I do it the right way!
>
> Falling back to reading the file is fine.  So we're assuming that the
> person signing a policy containing "get_hash" understands the
> ramifications.  And yes, only signed policies containing "get_hash"
> should be loaded.

I'm not clear on why requiring signed policies is helpful here. If you
allow FUSE mounts at all then you need to trust the FUSE filesystem to
return good results, in which case you can trust it to return valid
hashes. If you don't trust the FUSE filesystem then generating the
hash via read doesn't win you anything - the filesystem can return one
set of data on the initial IMA hashing, and then return a second set
later. Requiring signed policy doesn't change that.

  reply	other threads:[~2019-03-04 22:10 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-26 21:50 Allow trusted filesystems to provide IMA hashes directly Matthew Garrett
2019-02-26 21:50 ` [PATCH V2 1/4] VFS: Add a call to obtain a file's hash Matthew Garrett
2019-02-26 21:50 ` [PATCH V2 2/4] IMA: Allow rule matching on filesystem subtype Matthew Garrett
2019-02-26 21:50 ` [PATCH V2 3/4] IMA: Optionally make use of filesystem-provided hashes Matthew Garrett
2019-02-28 16:03   ` Mimi Zohar
2019-02-28 18:05     ` Mimi Zohar
2019-02-28 21:41       ` Matthew Garrett
2019-02-28 21:59         ` Mimi Zohar
2019-02-28 22:38           ` Matthew Garrett
2019-03-04 19:52             ` Matthew Garrett
2019-03-04 20:32               ` Mimi Zohar
2019-03-04 22:10                 ` Matthew Garrett [this message]
2019-03-05 13:18                   ` Mimi Zohar
2019-03-05 18:39                     ` Matthew Garrett
2019-03-05 19:51                       ` Mimi Zohar
2019-03-05 20:27                         ` Matthew Garrett
2019-03-06 12:30                           ` Mimi Zohar
2019-03-06 18:31                             ` Matthew Garrett
2019-03-06 22:38                               ` Mimi Zohar
2019-03-06 23:36                                 ` Matthew Garrett
2019-03-07  1:54                                   ` Mimi Zohar
2019-03-07  4:19                                     ` Matthew Garrett
2019-03-07 20:48                                       ` Mimi Zohar
2019-03-07 22:41                                         ` Matthew Garrett
2019-04-04 21:46                                           ` Matthew Garrett
2019-04-04 22:18                                             ` James Bottomley
2019-04-04 22:26                                               ` Matthew Garrett
2019-04-04 22:35                                                 ` James Bottomley
2019-04-05  1:50                                                   ` Matthew Garrett
2019-04-05  2:26                                                     ` James Bottomley
2019-04-05 20:55                                                       ` Matthew Garrett
2019-04-29 22:51                                                         ` Matthew Garrett
2019-05-02 20:25                                                           ` Mimi Zohar
2019-05-02 22:37                                                             ` Matthew Garrett
2019-05-02 23:02                                                               ` Mimi Zohar
2019-05-03  6:51                                                                 ` Roberto Sassu
2019-05-03  8:17                                                                   ` Roberto Sassu
2019-05-03 12:47                                                                     ` Mimi Zohar
2019-05-03 13:20                                                                       ` Roberto Sassu
2019-02-26 21:50 ` [PATCH V2 4/4] FUSE: Allow filesystems to provide gethash methods Matthew Garrett
2019-02-27 14:26   ` Jann Horn

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