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From: Mimi Zohar <zohar@linux.ibm.com>
To: Matthew Garrett <mjg59@google.com>
Cc: linux-integrity <linux-integrity@vger.kernel.org>,
	David Howells <dhowells@redhat.com>,
	Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
Subject: Re: [RFC] kexec: Allow kexec_file() with appropriate IMA policy when locked down
Date: Thu, 14 Mar 2019 18:31:31 -0400	[thread overview]
Message-ID: <1552602691.8658.49.camel@linux.ibm.com> (raw)
In-Reply-To: <CACdnJuv=-Gr9Psd1ABZ=fW43-2FHcgEkG_iu0bY20Jx4Vro=mA@mail.gmail.com>

On Thu, 2019-03-14 at 14:08 -0700, Matthew Garrett wrote:
> On Wed, Mar 13, 2019 at 6:08 PM Mimi Zohar <zohar@linux.ibm.com> wrote:
> > The IMA hash and EVM hmac combination is fine for offline protection.
> > It's used for mutable files.  For immutable files, there must be
> > either an IMA or EVM signature.
> 
> Ok. Is the correct way to handle this to check that the file has a
> signature, or to extend IMA policy to allow it to provide a
> requirement that EVM verify a signature rather than an HMAC and have
> the arch policy set that?

I'm not sure what you mean by "check that the file has a signature".

EVM and IMA are separate subsystems with a defined interface for
interaction between them. evm_verifyxattr() isn't, but could be called
by LSMs.  So evm_verifyxattr() would need to be extended to return the
EVM xattr type.  The IMA policy could then require a specific evmxattr
type.  Possible.

Perhaps for now require IMA signatures and defer supporting EVM
signatures?

Mimi





  reply	other threads:[~2019-03-14 22:31 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-12 19:57 [RFC] kexec: Allow kexec_file() with appropriate IMA policy when locked down Matthew Garrett
2019-03-13 11:58 ` Mimi Zohar
2019-03-13 20:36   ` Matthew Garrett
2019-03-13 21:29     ` Mimi Zohar
2019-03-13 21:59       ` Matthew Garrett
2019-03-14  1:08         ` Mimi Zohar
2019-03-14 21:08           ` Matthew Garrett
2019-03-14 22:31             ` Mimi Zohar [this message]
2019-03-14 22:54               ` Matthew Garrett
2019-03-14 23:58                 ` Mimi Zohar
2019-03-15 22:03                   ` Matthew Garrett
2019-03-17 11:39                     ` Mimi Zohar
2019-03-17 11:39                       ` Mimi Zohar
2019-03-18 19:51                       ` Matthew Garrett
2019-03-18 19:51                         ` Matthew Garrett

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