From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CACE416419; Thu, 7 Nov 2024 06:24:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730960651; cv=none; b=XmQLIxuAAbL4/PcwS43sYWbhaq3UO7xMmyanCntkAlpjGd0cOOswQRNS6G2cxAyaL8X/Gt/8LGt4z+i408Lt7sCZZUB4K4VLL+bJ7N/hxd1DfvBO6h4qnEL6jrQFrYolcoWyKR0InDGKtxXsxAK4ldrEhNLcjgom02XGypB2pvk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730960651; c=relaxed/simple; bh=JCiisxEYbTzX9rH/fwN6Tp3/oMIqUY575iDAgbG1l9s=; h=Mime-Version:Content-Type:Date:Message-Id:From:To:Cc:Subject: References:In-Reply-To; b=mitcqSI+rmT3T9vDnqUvoHFf4CNLhyCANOMzUrcwPIgajASCpHqJKvew7HQgv2JA3RlRrfl/A9LQ6M291SRB3eYd/NF0o4f1Tqb1fZqkPhjQtM5qFguQULmqfr5Je3IIBRvStYXbuopfS4CS7bBTFD/s5s6N1EQmrNO6IpVdvYE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Al8KTCxo; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Al8KTCxo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B0EF6C4CECC; Thu, 7 Nov 2024 06:24:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730960651; bh=JCiisxEYbTzX9rH/fwN6Tp3/oMIqUY575iDAgbG1l9s=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Al8KTCxoukmyEOId2O0zRcaGFjAWbBs9K4ms9/7QEwL0DLO5fs7U8chUCD9KKVrLO CcDQPgeKX3f//Yh1wxv8qRJzpeRVqayCyGrULaK0JV4oeRpyooHRyzMDZlvAO+K6t1 24y5KJfk2xMfQfVETpBPAHK7ajpt4W66gsWuNEDZzO72wYGFwvVkUlU6qDFQHXjspS TYE4lPAQiOpAej5eu7eU1imuLWW5u5Wy8z3XOMo8y2MKkQ2/OBqH+e65k8xQMqzIZM TzfvY5OEgz6ZUJ5skYMxuURfvHIb9PgDcBWD7D/mdKEXH+wcWOOJ58ILMciPBseiti EHpKzEEDOcnfA== Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Thu, 07 Nov 2024 08:24:06 +0200 Message-Id: From: "Jarkko Sakkinen" To: "Mimi Zohar" , , "Jonathan Corbet" , "Peter Huewe" , "Jason Gunthorpe" , "James Bottomley" Cc: "Roberto Sassu" , , Subject: Re: [PATCH] tpm: Opt-in in disable PCR encryption on TPM2 chips X-Mailer: aerc 0.18.2 References: <20241107004708.108667-1-jarkko@kernel.org> In-Reply-To: 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 > > >=20 > > > The initial encrypted HMAC session feature added TPM bus encryption t= o > > > various in-kernel TPM operations. This can cause performance bottlene= cks > > > with IMA, as it heavily utilizes PCR extend operations. > > The patch Subject line and problem description aren't quite right. In th= e case > of TPM pcr_extend, the session isn't being encrypted, only HMAC'ed. Acco= rding > to James, it's the HMAC itself that is causing the performance degradatio= n. 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