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 818754C7D; Thu, 7 Nov 2024 00:52:01 +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=1730940721; cv=none; b=Y1IGyo/qu11Mjn/wA71EJMCDitpYGj/ck/C61MPEsbhq3chP27qxDsucwanCWxh93bKj34lXpO++9xayKhxHGmma6NMBXoBnzL7Cr6l9VteoGMI3kzfsoaXhJLWgxBQwZ3JlH3EmZD6aiZfylAYmJC7YbKUBA1VBl7No3rYAECg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730940721; c=relaxed/simple; bh=hU987Sf5eZ+0DmQup+RdtNrqG3SHoFUU0Kwu4CfzrVo=; h=Mime-Version:Content-Type:Date:Message-Id:To:Cc:Subject:From: References:In-Reply-To; b=hrng2J4V8XQn4/RIXk+VelHK5W9r0zLSn1tnvc3Jsb9RK9wmmfdNXtqchJdWF+3Fa7Oq9JWovZb0YfgcXvWjJiWcGWzZ7O9qp20B9M9dgnxtz3zHcOspqjTqzKmFq/7gnojoZtjyOk02TykPUGZePyvhBTr/20dMHDyNIXtpDEU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Lun9GOBT; 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="Lun9GOBT" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 35FC6C4CEC6; Thu, 7 Nov 2024 00:51:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730940721; bh=hU987Sf5eZ+0DmQup+RdtNrqG3SHoFUU0Kwu4CfzrVo=; h=Date:To:Cc:Subject:From:References:In-Reply-To:From; b=Lun9GOBTa/ft2NFRUCWvMaPzmYe7VKRKGHWQOnMifNMSMtgcE3hNteEojno25yChH 9CBLzZ57PjukimQsFzzhW8wpnrHIrn+j888pcKdu1O70vuopLXVRAPNvwWx+yqk5Yc HLn3X+j8xkvsAaDbQ+7nQee9yg9vU6ZsbDWTV1DTpGYrTw3Xim9hrHOep6kM8uBgOA cMLH6hrYUJ2V5A6JOgMv/qvOeauEOrEF7hGIiWswv2sABz1YC/OBDybi0EAMjK5a4i dLfMfdEqc7ZPyk1XnasQxLp/qFFJn4iXUaT9abKS1AAherdYvvI/3r+OTF/PtrfwSm M5qYJzRNu4ONA== 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 02:51:56 +0200 Message-Id: To: "Jarkko Sakkinen" , , "Jonathan Corbet" , "Peter Huewe" , "Jason Gunthorpe" , "James Bottomley" Cc: "Mimi Zohar" , "Roberto Sassu" , , Subject: Re: [PATCH] tpm: Opt-in in disable PCR encryption on TPM2 chips From: "Jarkko Sakkinen" X-Mailer: aerc 0.18.2 References: <20241107004708.108667-1-jarkko@kernel.org> In-Reply-To: <20241107004708.108667-1-jarkko@kernel.org> On Thu Nov 7, 2024 at 2:47 AM EET, Jarkko Sakkinen wrote: > From: Mimi Zohar > > 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. > > In order to address this performance issue, introduce disable_encrypt_pcr= s > kernel command-line parameter to the TPM driver. > > Cc: James Bottomley > Link: https://lore.kernel.org/linux-integrity/20241015193916.59964-1-zoha= r@linux.ibm.com/ > Fixes: 6519fea6fd37 ("tpm: add hmac checks to tpm2_pcr_extend()") > Co-developed-by: Roberto Sassu > Signed-off-by: Roberto Sassu > Signed-off-by: Mimi Zohar > Co-developed-by: Jarkko Sakkinen > Signed-off-by: Jarkko Sakkinen > --- > v1: > - Derived from the earlier RFC patch with a different parameter scope, > cleaner commit message and some other tweaks. I decided to create > something because I did not noticed any progress. Note only compile > tested as I wanted to get something quickly out. > --- Noticed a couple of things I missed after sending this (see below). > .../admin-guide/kernel-parameters.txt | 10 ++++ > drivers/char/tpm/tpm2-cmd.c | 33 ++++++++--- > drivers/char/tpm/tpm2-sessions.c | 59 +++++++++++-------- > include/linux/tpm.h | 4 ++ > 4 files changed, 74 insertions(+), 32 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentat= ion/admin-guide/kernel-parameters.txt > index 1518343bbe22..e27517e1a26f 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -6727,6 +6727,16 @@ > torture.verbose_sleep_duration=3D [KNL] > Duration of each verbose-printk() sleep in jiffies. > =20 > + tpm.disable_encrypt_pcrs=3D [HW,TPM] > + Do not protect PCR registers from unintended physical > + access, or interposers in the bus by the means of > + having an encrypted and integrity protected session > + wrapped around TPM2_PCR_Extend command. Consider this > + in a situation where TPM is heavily utilized by > + IMA, thus protection causing a major performance hit, > + and the space where machines are deployed is by other > + means guarded. > + > tpm_suspend_pcr=3D[HW,TPM] > Format: integer pcr id > Specify that at suspend time, the tpm driver > diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c > index 1e856259219e..6ec307b1cb99 100644 > --- a/drivers/char/tpm/tpm2-cmd.c > +++ b/drivers/char/tpm/tpm2-cmd.c > @@ -14,6 +14,10 @@ > #include "tpm.h" > #include > =20 > +static bool disable_encrypt_pcrs; > +module_param(disable_encrypt_pcrs, bool, 0444); > +MODULE_PARM_DESC(disable_encrypt_pcrs, "Disable TPM2_PCR_Extend encrypti= on"); > + > static struct tpm2_hash tpm2_hash_map[] =3D { > {HASH_ALGO_SHA1, TPM_ALG_SHA1}, > {HASH_ALGO_SHA256, TPM_ALG_SHA256}, > @@ -232,18 +236,26 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_= idx, > int rc; > int i; > =20 > - rc =3D tpm2_start_auth_session(chip); > - if (rc) > - return rc; > + if (!disable_encrypt_pcrs) { > + rc =3D tpm2_start_auth_session(chip); > + if (rc) > + return rc; > + } > =20 > rc =3D tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND); > if (rc) { > - tpm2_end_auth_session(chip); > + if (!disable_encrypt_pcrs) > + tpm2_end_auth_session(chip); > return rc; > } > =20 > - tpm_buf_append_name(chip, &buf, pcr_idx, NULL); > - tpm_buf_append_hmac_session(chip, &buf, 0, NULL, 0); > + if (!disable_encrypt_pcrs) { > + tpm_buf_append_name(chip, &buf, pcr_idx, NULL); > + tpm_buf_append_hmac_session(chip, &buf, 0, NULL, 0); > + } else { > + tpm_buf_append_handle(chip, &buf, pcr_idx, NULL); > + tpm_buf_append_auth(chip, &buf, 0, NULL, 0); > + } > =20 > tpm_buf_append_u32(&buf, chip->nr_allocated_banks); > =20 > @@ -253,9 +265,12 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_i= dx, > chip->allocated_banks[i].digest_size); > } > =20 > - tpm_buf_fill_hmac_session(chip, &buf); > - rc =3D tpm_transmit_cmd(chip, &buf, 0, "attempting extend a PCR value")= ; > - rc =3D tpm_buf_check_hmac_response(chip, &buf, rc); > + if (!disable_encrypt_pcrs) > + tpm_buf_fill_hmac_session(chip, &buf); > + rc =3D tpm_transmit_cmd(chip, &buf, 0, > + "attempting extend a PCR value"); Should be in a single line in order to minimize the diff. > + if (!disable_encrypt_pcrs) > + rc =3D tpm_buf_check_hmac_response(chip, &buf, rc); > =20 > tpm_buf_destroy(&buf); > =20 > diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-ses= sions.c > index 42df980168b6..02897debc3fa 100644 > --- a/drivers/char/tpm/tpm2-sessions.c > +++ b/drivers/char/tpm/tpm2-sessions.c > @@ -205,6 +205,14 @@ static int tpm2_read_public(struct tpm_chip *chip, u= 32 handle, char *name) > } > #endif /* CONFIG_TCG_TPM2_HMAC */ > =20 > +void tpm_buf_append_handle(struct tpm_chip *chip, struct tpm_buf *buf, > + u32 handle, u8 *name) > +{ > + tpm_buf_append_u32(buf, handle); > + /* count the number of handles in the upper bits of flags */ > + buf->handles++; > +} > + > /** > * tpm_buf_append_name() - add a handle area to the buffer > * @chip: the TPM chip structure > @@ -237,9 +245,7 @@ void tpm_buf_append_name(struct tpm_chip *chip, struc= t tpm_buf *buf, > #endif > =20 > if (!tpm2_chip_auth(chip)) { > - tpm_buf_append_u32(buf, handle); > - /* count the number of handles in the upper bits of flags */ > - buf->handles++; > + tpm_buf_append_handle(chip, buf, handle, name); > return; > } > =20 > @@ -272,6 +278,31 @@ void tpm_buf_append_name(struct tpm_chip *chip, stru= ct tpm_buf *buf, > } > EXPORT_SYMBOL_GPL(tpm_buf_append_name); > =20 > +void tpm_buf_append_auth(struct tpm_chip *chip, struct tpm_buf *buf, > + u8 attributes, u8 *passphrase, int passphrase_len) > +{ > + /* offset tells us where the sessions area begins */ > + int offset =3D buf->handles * 4 + TPM_HEADER_SIZE; > + u32 len =3D 9 + passphrase_len; > + > + if (tpm_buf_length(buf) !=3D offset) { > + /* not the first session so update the existing length */ > + len +=3D get_unaligned_be32(&buf->data[offset]); > + put_unaligned_be32(len, &buf->data[offset]); > + } else { > + tpm_buf_append_u32(buf, len); > + } > + /* auth handle */ > + tpm_buf_append_u32(buf, TPM2_RS_PW); > + /* nonce */ > + tpm_buf_append_u16(buf, 0); > + /* attributes */ > + tpm_buf_append_u8(buf, 0); > + /* passphrase */ > + tpm_buf_append_u16(buf, passphrase_len); > + tpm_buf_append(buf, passphrase, passphrase_len); > +} > + > /** > * tpm_buf_append_hmac_session() - Append a TPM session element > * @chip: the TPM chip structure > @@ -309,26 +340,8 @@ void tpm_buf_append_hmac_session(struct tpm_chip *ch= ip, struct tpm_buf *buf, > #endif > =20 > if (!tpm2_chip_auth(chip)) { > - /* offset tells us where the sessions area begins */ > - int offset =3D buf->handles * 4 + TPM_HEADER_SIZE; > - u32 len =3D 9 + passphrase_len; > - > - if (tpm_buf_length(buf) !=3D offset) { > - /* not the first session so update the existing length */ > - len +=3D get_unaligned_be32(&buf->data[offset]); > - put_unaligned_be32(len, &buf->data[offset]); > - } else { > - tpm_buf_append_u32(buf, len); > - } > - /* auth handle */ > - tpm_buf_append_u32(buf, TPM2_RS_PW); > - /* nonce */ > - tpm_buf_append_u16(buf, 0); > - /* attributes */ > - tpm_buf_append_u8(buf, 0); > - /* passphrase */ > - tpm_buf_append_u16(buf, passphrase_len); > - tpm_buf_append(buf, passphrase, passphrase_len); > + tpm_buf_append_auth(chip, buf, attributes, passphrase, > + passphrase_len); > return; > } > =20 > diff --git a/include/linux/tpm.h b/include/linux/tpm.h > index 587b96b4418e..4892cd004530 100644 > --- a/include/linux/tpm.h > +++ b/include/linux/tpm.h > @@ -502,9 +502,13 @@ static inline struct tpm2_auth *tpm2_chip_auth(struc= t tpm_chip *chip) > =20 > void tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf, > u32 handle, u8 *name); > +void tpm_buf_append_handle(struct tpm_chip *chip, struct tpm_buf *buf, > + u32 handle, u8 *name); > void tpm_buf_append_hmac_session(struct tpm_chip *chip, struct tpm_buf *= buf, > u8 attributes, u8 *passphrase, > int passphraselen); > +void tpm_buf_append_auth(struct tpm_chip *chip, struct tpm_buf *buf, > + u8 attributes, u8 *passphrase, int passphraselen); This is declared in wrong place as it has no outside callers. So I will move it to drivers/char/tpm/tpm.h instead. Please correct if I'm overlooking something. > static inline void tpm_buf_append_hmac_session_opt(struct tpm_chip *chip= , > struct tpm_buf *buf, > u8 attributes, BR, Jarkko