From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752660AbbJRLTa (ORCPT ); Sun, 18 Oct 2015 07:19:30 -0400 Received: from mga14.intel.com ([192.55.52.115]:5572 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752217AbbJRLT2 (ORCPT ); Sun, 18 Oct 2015 07:19:28 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.17,697,1437462000"; d="scan'208";a="829339521" Date: Sun, 18 Oct 2015 14:19:24 +0300 From: Jarkko Sakkinen To: Peter =?iso-8859-1?Q?H=FCwe?= Cc: tpmdd-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org, jgunthorpe@obsidianresearch.com, dhowells@redhat.com, artem.bityutskiy@linux.intel.com, Marcel Selhorst Subject: Re: [PATCH 06/10] tpm: introduce tpm_buf Message-ID: <20151018111923.GB7391@intel.com> References: <1445020843-9382-1-git-send-email-jarkko.sakkinen@linux.intel.com> <1445020843-9382-7-git-send-email-jarkko.sakkinen@linux.intel.com> <201510180457.49277.PeterHuewe@gmx.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <201510180457.49277.PeterHuewe@gmx.de> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Oct 18, 2015 at 04:57:49AM +0200, Peter Hüwe wrote: > Am Freitag, 16. Oktober 2015, 20:40:25 schrieb Jarkko Sakkinen: > > This patch introduces struct tpm_buf that provides a string buffer for > > constructing TPM commands. This allows to construct variable sized TPM > > commands. For the buffer a page is allocated and mapped, which limits > > maximum size to PAGE_SIZE. > > > > Variable sized TPM commands are needed in order to add algorithmic > > agility. > > > > Signed-off-by: Jarkko Sakkinen > > --- > > drivers/char/tpm/tpm.h | 97 > > ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 97 > > insertions(+) > > > > diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h > > index 36ceb71..cb46f62 100644 > > --- a/drivers/char/tpm/tpm.h > > +++ b/drivers/char/tpm/tpm.h > > @@ -1,5 +1,6 @@ > > /* > > * Copyright (C) 2004 IBM Corporation > > + * Copyright (C) 2015 Intel Corporation > > * > > * Authors: > > * Leendert van Doorn > > @@ -28,6 +29,7 @@ > > #include > > #include > > #include > > +#include > > > > enum tpm_const { > > TPM_MINOR = 224, /* officially assigned */ > > @@ -390,6 +392,101 @@ struct tpm_cmd_t { > > tpm_cmd_params params; > > } __packed; > > > > +/* A string buffer type for constructing TPM commands. This is based on > > the + * ideas of string buffer code in security/keys/trusted.h but is heap > > based + * in order to keep the stack usage minimal. > > + */ > > + > > +enum tpm_buf_flags { > > + TPM_BUF_OVERFLOW = BIT(0), > > +}; > > + > > +struct tpm_buf { > > + struct page *data_page; > > + unsigned int flags; > > + u8 *data; > > +}; > > + > > +static inline void tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal) > > +{ > > + struct tpm_input_header *head; > > + > > + buf->data_page = alloc_page(GFP_HIGHUSER); > > + if (!buf->data_page) > > + return -ENOMEM; > > + > > + buf->flags = 0; > > + buf->data = kmap(buf->data_page); > > + > > + head = (struct tpm_input_header *) buf->data; > > + > > + head->tag = cpu_to_be16(tag); > > + head->length = cpu_to_be32(sizeof(*head)); > > + head->ordinal = cpu_to_be32(ordinal); > > + > > + return 0; > > +} > > + > > +static inline void tpm_buf_destroy(struct tpm_buf *buf) > > +{ > > + kunmap(buf->data_page); > > + __free_page(buf->data_page); > > +} > > + > > +static inline u32 tpm_buf_length(struct tpm_buf *buf) > > +{ > > + struct tpm_input_header *head = (struct tpm_input_header *) buf->data; > > + > > + return be32_to_cpu(head->length); > > +} > > + > > +static inline u16 tpm_buf_tag(struct tpm_buf *buf) > > +{ > > + struct tpm_input_header *head = (struct tpm_input_header *) buf->data; > > + > > + return be16_to_cpu(head->tag); > > +} > > + > > +static inline void tpm_buf_append(struct tpm_buf *buf, > > + const unsigned char *new_data, > > + unsigned int new_len) > > +{ > > + struct tpm_input_header *head = (struct tpm_input_header *) buf->data; > > + u32 len = tpm_buf_length(buf); > > > > + > > + /* Return silently if overflow has already happened. */ > > + if (buf->flags & TPM_BUF_OVERFLOW) > > + return; > > + > > + if ((len + new_len) > PAGE_SIZE) { > > + WARN(1, "tpm_buf: overflow\n"); > > + buf->flags |= TPM_BUF_OVERFLOW; > > + return; > > + } > Why not use WARN_ONCE? Does it matter? Message is emitted only once since it does not sense to even try to add new data if overflow flag has been set. I.e. even if I had WARN_ONCE there I still would have the check for overflow flag before this. /Jarkko