From: "Jarkko Sakkinen" <jarkko@kernel.org>
To: "Mimi Zohar" <zohar@linux.ibm.com>,
<linux-integrity@vger.kernel.org>,
"Jonathan Corbet" <corbet@lwn.net>,
"Peter Huewe" <peterhuewe@gmx.de>,
"Jason Gunthorpe" <jgg@ziepe.ca>,
"James Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: "Roberto Sassu" <roberto.sassu@huawei.com>,
<linux-doc@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] tpm: Opt-in in disable PCR encryption on TPM2 chips
Date: Thu, 07 Nov 2024 08:24:06 +0200 [thread overview]
Message-ID: <D5FQC7G8OUAO.1A449Z8ADEA0E@kernel.org> (raw)
In-Reply-To: <b510e556621e3826dd6df043fde817192b9f12ea.camel@linux.ibm.com>
On Thu Nov 7, 2024 at 4:48 AM EET, Mimi Zohar wrote:
> On Thu, 2024-11-07 at 02:51 +0200, Jarkko Sakkinen wrote:
> > On Thu Nov 7, 2024 at 2:47 AM EET, Jarkko Sakkinen wrote:
> > > From: Mimi Zohar <zohar@linux.ibm.com>
> > >
> > > The initial encrypted HMAC session feature added TPM bus encryption to
> > > various in-kernel TPM operations. This can cause performance bottlenecks
> > > with IMA, as it heavily utilizes PCR extend operations.
>
> The patch Subject line and problem description aren't quite right. In the case
> of TPM pcr_extend, the session isn't being encrypted, only HMAC'ed. According
> to James, it's the HMAC itself that is causing the performance degradation. I
> would remove the word "encrypted" throughout.
I have to say I disagree with that. Encryption is the feature we get
with HMAC and is more understandable for most. HMAC is implemnetation
detail.
BR, Jarkko
next prev parent reply other threads:[~2024-11-07 6:24 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-11-07 0:47 [PATCH] tpm: Opt-in in disable PCR encryption on TPM2 chips Jarkko Sakkinen
2024-11-07 0:51 ` Jarkko Sakkinen
2024-11-07 0:54 ` Jarkko Sakkinen
2024-11-07 2:48 ` Mimi Zohar
2024-11-07 6:24 ` Jarkko Sakkinen [this message]
2024-11-07 6:27 ` Jarkko Sakkinen
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=D5FQC7G8OUAO.1A449Z8ADEA0E@kernel.org \
--to=jarkko@kernel.org \
--cc=James.Bottomley@HansenPartnership.com \
--cc=corbet@lwn.net \
--cc=jgg@ziepe.ca \
--cc=linux-doc@vger.kernel.org \
--cc=linux-integrity@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=peterhuewe@gmx.de \
--cc=roberto.sassu@huawei.com \
--cc=zohar@linux.ibm.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).