From: Mimi Zohar <zohar@linux.vnet.ibm.com>
To: Matthew Garrett <mjg59@google.com>
Cc: linux-integrity@vger.kernel.org,
Mikhail Kurinnoi <viewizard@viewizard.com>
Subject: Re: RFC: Make it practical to ship EVM signatures
Date: Mon, 02 Oct 2017 15:54:28 -0400 [thread overview]
Message-ID: <1506974068.5691.300.camel@linux.vnet.ibm.com> (raw)
In-Reply-To: <CACdnJuv11cjDHac6M+iofB7yA=on2N5ZiqXz8onZZPtGFgo7yA@mail.gmail.com>
On Mon, 2017-10-02 at 10:09 -0700, Matthew Garrett wrote:
> On Sat, Sep 30, 2017 at 7:36 PM, Mimi Zohar <zohar@linux.vnet.ibm.com> wrote:
> > On Fri, 2017-09-29 at 13:09 -0700, Matthew Garrett wrote:
> >> If the security metadata is different then copying another
> >> security.evm will fail, surely?
> >
> > A copy of the file could exist with a valid hmac on the system with
> > different security xattrs. Without the inode/uuid, the xattrs could
> > be cut & pasted.
>
> So we have /usr/bin/a and /usr/bin/b, which are identical but have
> different security contexts. Outside some unusual cases, if I have the
> ability to modify /usr/bin/b's security.evm, I can delete /usr/bin/b.
> I can then also just do:
>
> ln -f /usr/bin/a /usr/bin/b
>
> and /usr/bin/b now has the same security context as /usr/bin/a,
> including security.evm.
All true, but instead of /usr/bin/a and /usr/bin/b, which most likely
have the same LSM labels, think of it in terms of /home/bin/b. An
offline attack wouldn't require access to the EVM HMAC key or any
privileges.
Mimi
next prev parent reply other threads:[~2017-10-02 19:54 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-27 22:16 RFC: Make it practical to ship EVM signatures Matthew Garrett
2017-09-27 22:16 ` [PATCH 1/6] IMA: Allow EVM validation on appraisal even without a symmetric key Matthew Garrett
2017-10-01 2:08 ` Mimi Zohar
2017-10-02 17:02 ` Matthew Garrett
2017-10-02 19:41 ` Mimi Zohar
2017-09-27 22:16 ` [PATCH 2/6] EVM: Add infrastructure for making EVM fields optional Matthew Garrett
2017-09-27 22:16 ` [PATCH 3/6] EVM: Allow userland to override the default EVM attributes Matthew Garrett
2017-09-27 22:16 ` [PATCH 4/6] EVM: Add an hmac_ng xattr format Matthew Garrett
2017-09-27 22:16 ` [PATCH 5/6] EVM: Write out HMAC xattrs in the new format Matthew Garrett
2017-09-27 22:16 ` [PATCH 6/6] EVM: Add a new digital signature format Matthew Garrett
2017-09-28 20:12 ` RFC: Make it practical to ship EVM signatures Mimi Zohar
2017-09-28 21:13 ` Matthew Garrett
2017-09-29 0:53 ` Mimi Zohar
2017-09-29 18:09 ` Matthew Garrett
2017-09-29 19:02 ` Mimi Zohar
2017-09-29 19:17 ` Matthew Garrett
2017-09-29 20:01 ` Mimi Zohar
2017-09-29 20:09 ` Matthew Garrett
2017-10-01 2:36 ` Mimi Zohar
2017-10-02 17:09 ` Matthew Garrett
2017-10-02 19:54 ` Mimi Zohar [this message]
[not found] ` <CACdnJutYw7Pgh-EwWuwp9Wz+5KzoreZVr+c6UV30zC__8FZSVA@mail.gmail.com>
[not found] ` <1506974574.5691.304.camel@linux.vnet.ibm.com>
2017-10-02 20:07 ` Matthew Garrett
2017-10-09 17:51 ` Mimi Zohar
2017-10-09 17:59 ` Matthew Garrett
2017-10-09 18:15 ` Mimi Zohar
2017-10-09 18:18 ` Matthew Garrett
2017-10-09 18:40 ` Mimi Zohar
[not found] ` <20171009232314.545de76a@totoro>
[not found] ` <1507583449.3748.46.camel@linux.vnet.ibm.com>
[not found] ` <20171010003326.6409ae23@totoro>
2017-10-09 21:40 ` Mimi Zohar
2017-10-09 23:10 ` Mikhail Kurinnoi
2017-10-10 19:07 ` Mimi Zohar
2017-10-12 23:09 ` Dmitry Kasatkin
2017-10-18 19:48 ` Dmitry Kasatkin
2017-10-18 20:30 ` Mimi Zohar
2017-10-18 20:37 ` Dmitry Kasatkin
2017-10-18 21:02 ` Mikhail Kurinnoi
2017-10-18 21:07 ` Mimi Zohar
2017-10-19 10:14 ` Dmitry Kasatkin
2017-10-19 11:43 ` Mimi Zohar
2017-10-19 17:08 ` Matthew Garrett
2017-10-19 18:38 ` Dmitry Kasatkin
2017-10-19 10:36 ` Dmitry Kasatkin
2017-10-19 11:45 ` Mimi Zohar
2017-10-02 14:53 ` Roberto Sassu
2017-10-02 8:55 ` Roberto Sassu
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