From: Dan Williams <dan.j.williams@intel.com>
To: James Bottomley <James.Bottomley@hansenpartnership.com>,
"Kuppuswamy Sathyanarayanan"
<sathyanarayanan.kuppuswamy@linux.intel.com>,
"Xing, Cedric" <cedric.xing@intel.com>,
Dan Williams <dan.j.williams@intel.com>,
"Dan Middleton" <dan.middleton@linux.intel.com>,
Samuel Ortiz <sameo@rivosinc.com>
Cc: Qinkun Bao <qinkun@google.com>,
"Yao, Jiewen" <jiewen.yao@intel.com>,
Dionna Amalie Glaze <dionnaglaze@google.com>, <biao.lu@intel.com>,
<linux-coco@lists.linux.dev>, <linux-integrity@vger.kernel.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH v2 0/4] tsm: Runtime measurement registers ABI
Date: Fri, 9 Feb 2024 12:58:09 -0800 [thread overview]
Message-ID: <65c691e13a50d_afa42948a@dwillia2-xfh.jf.intel.com.notmuch> (raw)
In-Reply-To: <332775d7218843d6cc168c963d76e6841eab5d5b.camel@HansenPartnership.com>
James Bottomley wrote:
> On Wed, 2024-02-07 at 13:08 -0800, Kuppuswamy Sathyanarayanan wrote:
> >
> > On 2/7/24 12:16 PM, Xing, Cedric wrote:
> > > On 2/6/2024 6:02 PM, Dan Williams wrote:
> > > > James Bottomley wrote:
> > > > > There isn't really anything more complex about an interface
> > > > > that takes a log entry, and does the record an extend, than an
> > > > > interface which takes a PCR extension value. So best practice
> > > > > would say that you should create the ABI that you can't get
> > > > > wrong (log and record) rather than creating one that causes
> > > > > additional problems for userspace.
> > > >
> > > > Agree, there's no need for the kernel to leave deliberately
> > > > pointy edges for userspace to trip over.
> > > >
> > > > Cedric, almost every time we, kernel community, build an
> > > > interface where userspace says "trust us, we know what we are
> > > > doing" it inevitably results later in "whoops, turns out it would
> > > > have helped if the kernel enforced structure here". So the log
> > > > ABI adds that structure for the primary use cases.
> > >
> > > Dan, I agree with your statement generally. But with the precedent
> > > of TPM module not maintaining a log, I just wonder if the addition
> > > of log would cause problems or force more changes to existing
> > > usages than necessary. For example, IMA has its own log and if
> > > changed to use RTMR, how would those 2 logs interoperate? We would
> > > also need to decide on a log format that can accommodate all
> > > applications.
> >
> >
> > IIUC, CC event logging in firmware uses TCG2 format. Since IMA
> > internally uses TPM calls, I assume it also uses the TCG2 format. I
> > think we can follow the same format for RTMR extension.
>
> Just to correct this: IMA uses its own log format, but I think this was
> a mistake long ago and the new log should use TCG2 format so all the
> tools know how to parse it.
Is this a chance to nudge IMA towards a standard log format? In other
words, one of the goals alongside userspace consumers of the RTMR log
would be for IMA to support it as well as an alternate in-kernel backend
next to TPM. IMA-over-TPM continues with its current format,
IMA-over-RTMR internally unifies with the log format that is shared with
RTMR-user-ABI.
...but be warned the above is a comment from someone who knows nothing
about IMA internals, just reacting to the comment.
> > I am wondering where will the event log be stored? Is it in the
> > log_area region of CCEL table?
>
> IMA stores its log in kernel memory and makes it visible in securityfs
> (in the smae place as the measured boot log). Since this interface is
> using configfs, that's where I'd make the log visible.
>
> Just to add a note about how UEFI works: the measured boot log is
> effectively copied into kernel memory because the UEFI memory it once
> occupied is freed after exit boot services, so no UEFI interface will
> suffice for the log location.
>
> I'd make the file exporting it root owned but probably readable by only
> the people who can also extend it (presumably enforced by group?).
I assume EFI copying into kernel memory is ok because that log has a
limited number of entries. If this RTMR log gets large I assume it needs
some way cull entries that have been moved to storage. Maybe this is a
problem IMA has already solved.
next prev parent reply other threads:[~2024-02-09 20:58 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-28 21:25 [RFC PATCH v2 0/4] tsm: Runtime measurement registers ABI Samuel Ortiz
2024-01-28 21:25 ` [RFC PATCH v2 1/4] tsm: Runtime measurement register support Samuel Ortiz
2024-01-29 16:57 ` Dionna Amalie Glaze
2024-02-01 22:03 ` Jarkko Sakkinen
2024-01-28 21:25 ` [RFC PATCH v2 2/4] tsm: Add RTMRs to the configfs-tsm hierarchy Samuel Ortiz
2024-01-28 22:38 ` Kuppuswamy Sathyanarayanan
2024-02-01 22:05 ` Jarkko Sakkinen
2024-02-21 16:16 ` Mikko Ylinen
2024-01-28 21:25 ` [RFC PATCH v2 3/4] tsm: Map RTMRs to TCG TPM PCRs Samuel Ortiz
2024-01-28 22:44 ` Kuppuswamy Sathyanarayanan
2024-02-02 6:18 ` James Bottomley
2024-01-28 21:25 ` [RFC PATCH v2 4/4] tsm: Allow for extending and reading configured RTMRs Samuel Ortiz
2024-02-01 22:02 ` [RFC PATCH v2 0/4] tsm: Runtime measurement registers ABI Jarkko Sakkinen
2024-02-02 6:24 ` James Bottomley
2024-02-02 23:07 ` Dan Middleton
2024-02-03 6:03 ` James Bottomley
2024-02-03 7:13 ` Kuppuswamy Sathyanarayanan
2024-02-03 10:27 ` James Bottomley
2024-02-06 8:34 ` Xing, Cedric
2024-02-06 8:57 ` James Bottomley
2024-02-07 2:02 ` Dan Williams
2024-02-07 20:16 ` Xing, Cedric
2024-02-07 21:08 ` Kuppuswamy Sathyanarayanan
2024-02-07 21:46 ` James Bottomley
2024-02-09 20:58 ` Dan Williams [this message]
2024-02-13 7:36 ` Xing, Cedric
2024-02-13 16:05 ` James Bottomley
2024-02-14 8:54 ` Xing, Cedric
2024-02-15 6:14 ` Dan Williams
2024-02-16 2:05 ` Xing, Cedric
2024-03-05 1:19 ` Xing, Cedric
2024-04-17 20:23 ` Dan Middleton
2024-02-13 16:54 ` Mikko Ylinen
2024-02-15 22:44 ` Dr. Greg
2024-02-22 15:45 ` Lukas Wunner
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=65c691e13a50d_afa42948a@dwillia2-xfh.jf.intel.com.notmuch \
--to=dan.j.williams@intel.com \
--cc=James.Bottomley@hansenpartnership.com \
--cc=biao.lu@intel.com \
--cc=cedric.xing@intel.com \
--cc=dan.middleton@linux.intel.com \
--cc=dionnaglaze@google.com \
--cc=jiewen.yao@intel.com \
--cc=linux-coco@lists.linux.dev \
--cc=linux-integrity@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=qinkun@google.com \
--cc=sameo@rivosinc.com \
--cc=sathyanarayanan.kuppuswamy@linux.intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.