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To: Mimi Zohar <>,
	Janne Karhunen <>,,
	linux-security-module <>
Cc: Ken Goldman <>,, Amir Goldstein <>,
	linux-fsdevel <>
Subject: Re: [PATCH v2] ima: export the measurement list when needed
Date: Wed, 12 Feb 2020 16:08:15 -0500
Message-ID: <> (raw)
In-Reply-To: <>

On Tue, 2020-02-11 at 18:10 -0500, Mimi Zohar wrote:
> On Tue, 2020-02-11 at 11:10 -0500, wrote:

> > <snip>
> > 
> This new feature will require setting up some infrastructure for
> storing the partial measurement list(s) in order to validate a TPM
> quote.  Userspace already can save partial measurement list(s) without
> any kernel changes.  The entire measurement list does not need to be
> read each time.  lseek can read past the last record previously read.
>  The only new aspect is truncating the in kernel measurement list in
> order to free kernel memory.

This is a pretty important new feature.
A lot of people can't use IMA because of the memory issue.
Also, I really think we need to let administrators choose the tradeoffs
of keeping the list in memory, on a local file, or only on the 
attestation server, as best fits their use cases.
> < snip> 
> Until there is proof that the measurement list can be exported to a
> file before kexec, instead of carrying the measurement list across
> kexec, and a TPM quote can be validated after the kexec, there isn't a
> compelling reason for the kernel needing to truncate the measurement
> list.

If this approach doesn't work with all the kexec use cases, then it is 
useless, and the ball is in my court to prove that it does. Fortunately
I have to test that anyway for the coming TLV support.

Working on it...


> Mimi

  reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <>
     [not found] ` <>
2020-02-06 14:13   ` Mimi Zohar
2020-02-10  8:04     ` Janne Karhunen
2020-02-10 15:26       ` Mimi Zohar
2020-02-10 18:18     ` david.safford
2020-02-10 20:24       ` Mimi Zohar
2020-02-11  8:06         ` Janne Karhunen
2020-02-11 16:10         ` david.safford
2020-02-11 23:10           ` Mimi Zohar
2020-02-12 21:08             ` david.safford [this message]
2020-02-13  1:03               ` Mimi Zohar
2020-02-13  6:41                 ` Janne Karhunen
2020-02-18 15:36                   ` Mimi Zohar

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