From patchwork Fri Dec 9 16:06:01 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 13069944 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A9C7CC4332F for ; Fri, 9 Dec 2022 16:08:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229735AbiLIQIN (ORCPT ); Fri, 9 Dec 2022 11:08:13 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50856 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229988AbiLIQHk (ORCPT ); Fri, 9 Dec 2022 11:07:40 -0500 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [IPv6:2607:fcd0:100:8a00::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 158736315; Fri, 9 Dec 2022 08:07:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1670602057; bh=6GYeQtfa7umPGZCcxdOn/S9pKIsVxQ7tzahtek66SYQ=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References:From; b=rKqgyBXbNfTpOhxslE0dtg71a4iPTaWkfqej5oeKlTsy8SwEN86dP32Z28ki8Irnx UbyEj36BqeJla/QBYtqAHm0NG1hVB91WD48Rj1hjLGlec83oAk0I6xedbgWvxcJWM2 Kd2o3CDR0XVHXX+KOT3HxNTSeeLEvQILQutXdBHg= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id B88551286318; Fri, 9 Dec 2022 11:07:37 -0500 (EST) Received: from bedivere.hansenpartnership.com ([127.0.0.1]) by localhost (bedivere.hansenpartnership.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id DvoGA5jhRqRQ; Fri, 9 Dec 2022 11:07:37 -0500 (EST) Received: from lingrow.int.hansenpartnership.com (unknown [153.66.160.227]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 1EF581286316; Fri, 9 Dec 2022 11:07:37 -0500 (EST) From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Ard Biesheuvel , Jarkko Sakkinen , keyrings@vger.kernel.org Subject: [PATCH 01/11] tpm: move buffer handling from static inlines to real functions Date: Fri, 9 Dec 2022 11:06:01 -0500 Message-Id: <20221209160611.30207-2-James.Bottomley@HansenPartnership.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20221209160611.30207-1-James.Bottomley@HansenPartnership.com> References: <20221209160611.30207-1-James.Bottomley@HansenPartnership.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: keyrings@vger.kernel.org This separates out the old tpm_buf_... handling functions from static inlines in tpm.h and makes them their own tpm-buf.c file. This is a precursor so we can add new functions for other TPM type handling Signed-off-by: James Bottomley --- drivers/char/tpm/Makefile | 1 + drivers/char/tpm/tpm-buf.c | 96 ++++++++++++++++++++++++++++++++++++++ include/linux/tpm.h | 86 ++++------------------------------ 3 files changed, 106 insertions(+), 77 deletions(-) create mode 100644 drivers/char/tpm/tpm-buf.c diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile index 0222b1ddb310..ad3594e383e1 100644 --- a/drivers/char/tpm/Makefile +++ b/drivers/char/tpm/Makefile @@ -15,6 +15,7 @@ tpm-y += tpm-sysfs.o tpm-y += eventlog/common.o tpm-y += eventlog/tpm1.o tpm-y += eventlog/tpm2.o +tpm-y += tpm-buf.o tpm-$(CONFIG_ACPI) += tpm_ppi.o eventlog/acpi.o tpm-$(CONFIG_EFI) += eventlog/efi.o diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c new file mode 100644 index 000000000000..4e6e8b281f6a --- /dev/null +++ b/drivers/char/tpm/tpm-buf.c @@ -0,0 +1,96 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Handing for tpm_buf structures to facilitate the building of commands + */ + +#include +#include + +int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal) +{ + buf->data = (u8 *)__get_free_page(GFP_KERNEL); + if (!buf->data) + return -ENOMEM; + + buf->flags = 0; + tpm_buf_reset(buf, tag, ordinal); + return 0; +} +EXPORT_SYMBOL_GPL(tpm_buf_init); + +void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal) +{ + struct tpm_header *head = (struct tpm_header *) buf->data; + + head->tag = cpu_to_be16(tag); + head->length = cpu_to_be32(sizeof(*head)); + head->ordinal = cpu_to_be32(ordinal); +} +EXPORT_SYMBOL_GPL(tpm_buf_reset); + +void tpm_buf_destroy(struct tpm_buf *buf) +{ + free_page((unsigned long)buf->data); +} +EXPORT_SYMBOL_GPL(tpm_buf_destroy); + +u32 tpm_buf_length(struct tpm_buf *buf) +{ + struct tpm_header *head = (struct tpm_header *)buf->data; + + return be32_to_cpu(head->length); +} +EXPORT_SYMBOL_GPL(tpm_buf_length); + +u16 tpm_buf_tag(struct tpm_buf *buf) +{ + struct tpm_header *head = (struct tpm_header *)buf->data; + + return be16_to_cpu(head->tag); +} +EXPORT_SYMBOL_GPL(tpm_buf_tag); + +void tpm_buf_append(struct tpm_buf *buf, + const unsigned char *new_data, + unsigned int new_len) +{ + struct tpm_header *head = (struct tpm_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; + } + + memcpy(&buf->data[len], new_data, new_len); + head->length = cpu_to_be32(len + new_len); +} +EXPORT_SYMBOL_GPL(tpm_buf_append); + +void tpm_buf_append_u8(struct tpm_buf *buf, const u8 value) +{ + tpm_buf_append(buf, &value, 1); +} +EXPORT_SYMBOL_GPL(tpm_buf_append_u8); + +void tpm_buf_append_u16(struct tpm_buf *buf, const u16 value) +{ + __be16 value2 = cpu_to_be16(value); + + tpm_buf_append(buf, (u8 *) &value2, 2); +} +EXPORT_SYMBOL_GPL(tpm_buf_append_u16); + +void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value) +{ + __be32 value2 = cpu_to_be32(value); + + tpm_buf_append(buf, (u8 *) &value2, 4); +} +EXPORT_SYMBOL_GPL(tpm_buf_append_u32); diff --git a/include/linux/tpm.h b/include/linux/tpm.h index dfeb25a0362d..150b39b6190e 100644 --- a/include/linux/tpm.h +++ b/include/linux/tpm.h @@ -322,84 +322,16 @@ struct tpm2_hash { unsigned int tpm_id; }; -static inline void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal) -{ - struct tpm_header *head = (struct tpm_header *)buf->data; - - head->tag = cpu_to_be16(tag); - head->length = cpu_to_be32(sizeof(*head)); - head->ordinal = cpu_to_be32(ordinal); -} - -static inline int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal) -{ - buf->data = (u8 *)__get_free_page(GFP_KERNEL); - if (!buf->data) - return -ENOMEM; - - buf->flags = 0; - tpm_buf_reset(buf, tag, ordinal); - return 0; -} - -static inline void tpm_buf_destroy(struct tpm_buf *buf) -{ - free_page((unsigned long)buf->data); -} - -static inline u32 tpm_buf_length(struct tpm_buf *buf) -{ - struct tpm_header *head = (struct tpm_header *)buf->data; - - return be32_to_cpu(head->length); -} - -static inline u16 tpm_buf_tag(struct tpm_buf *buf) -{ - struct tpm_header *head = (struct tpm_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_header *head = (struct tpm_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; - } - memcpy(&buf->data[len], new_data, new_len); - head->length = cpu_to_be32(len + new_len); -} - -static inline void tpm_buf_append_u8(struct tpm_buf *buf, const u8 value) -{ - tpm_buf_append(buf, &value, 1); -} - -static inline void tpm_buf_append_u16(struct tpm_buf *buf, const u16 value) -{ - __be16 value2 = cpu_to_be16(value); - - tpm_buf_append(buf, (u8 *) &value2, 2); -} - -static inline void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value) -{ - __be32 value2 = cpu_to_be32(value); - - tpm_buf_append(buf, (u8 *) &value2, 4); -} +int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal); +void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal); +void tpm_buf_destroy(struct tpm_buf *buf); +u32 tpm_buf_length(struct tpm_buf *buf); +void tpm_buf_append(struct tpm_buf *buf, const unsigned char *new_data, + unsigned int new_len); +void tpm_buf_append_u8(struct tpm_buf *buf, const u8 value); +void tpm_buf_append_u16(struct tpm_buf *buf, const u16 value); +void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value); /* * Check if TPM device is in the firmware upgrade mode. From patchwork Fri Dec 9 16:06:02 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 13069945 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F3BAFC10F1E for ; Fri, 9 Dec 2022 16:08:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229555AbiLIQIT (ORCPT ); Fri, 9 Dec 2022 11:08:19 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50382 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229731AbiLIQIM (ORCPT ); Fri, 9 Dec 2022 11:08:12 -0500 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [IPv6:2607:fcd0:100:8a00::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C280D2AD3; Fri, 9 Dec 2022 08:08:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1670602091; bh=fRU/5tkj5hSyjein7ZOe18eXz7wQbqGj+RoDgHzE7K8=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References:From; b=sJuH7HEyUn7zkrZBUa6gDq+XSB6Ahk42MTE16qhWGWIR4S+EHt+5Wvt4gJsCsf+Cv 60+lNZn4ZoT4UqUrJ23VC+gYdgPc+wMq0hi5VoklBjLOlUn92vm7kBfEW+Wg+1dkXB Q1uOSqLj4NKOWREkuOTfRYMEXMePqocjph44BeyI= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 522A11286318; Fri, 9 Dec 2022 11:08:11 -0500 (EST) Received: from bedivere.hansenpartnership.com ([127.0.0.1]) by localhost (bedivere.hansenpartnership.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id dPlwnz8dVlRH; Fri, 9 Dec 2022 11:08:11 -0500 (EST) Received: from lingrow.int.hansenpartnership.com (unknown [153.66.160.227]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id B4D5E1286316; Fri, 9 Dec 2022 11:08:10 -0500 (EST) From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Ard Biesheuvel , Jarkko Sakkinen , keyrings@vger.kernel.org Subject: [PATCH 02/11] tpm: add buffer handling for TPM2B types Date: Fri, 9 Dec 2022 11:06:02 -0500 Message-Id: <20221209160611.30207-3-James.Bottomley@HansenPartnership.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20221209160611.30207-1-James.Bottomley@HansenPartnership.com> References: <20221209160611.30207-1-James.Bottomley@HansenPartnership.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: keyrings@vger.kernel.org Most complex TPM commands require appending TPM2B buffers to the command body. Since TPM2B types are essentially variable size arrays, it makes it impossible to represent these complex command arguments as structures and we simply have to build them up using append primitives like these. Signed-off-by: James Bottomley --- drivers/char/tpm/tpm-buf.c | 71 +++++++++++++++++++++++++++++++++++--- include/linux/tpm.h | 3 ++ 2 files changed, 69 insertions(+), 5 deletions(-) diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c index 4e6e8b281f6a..f1d48f22d4b4 100644 --- a/drivers/char/tpm/tpm-buf.c +++ b/drivers/char/tpm/tpm-buf.c @@ -7,17 +7,16 @@ #include #include -int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal) +static int __tpm_buf_init(struct tpm_buf *buf) { buf->data = (u8 *)__get_free_page(GFP_KERNEL); if (!buf->data) return -ENOMEM; buf->flags = 0; - tpm_buf_reset(buf, tag, ordinal); + return 0; } -EXPORT_SYMBOL_GPL(tpm_buf_init); void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal) { @@ -29,17 +28,60 @@ void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal) } EXPORT_SYMBOL_GPL(tpm_buf_reset); +int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal) +{ + int rc; + + rc = __tpm_buf_init(buf); + if (rc) + return rc; + + tpm_buf_reset(buf, tag, ordinal); + + return 0; +} +EXPORT_SYMBOL_GPL(tpm_buf_init); + +int tpm_buf_init_2b(struct tpm_buf *buf) +{ + struct tpm_header *head; + int rc; + + rc = __tpm_buf_init(buf); + if (rc) + return rc; + + head = (struct tpm_header *) buf->data; + + head->length = cpu_to_be32(sizeof(*head)); + + buf->flags = TPM_BUF_2B; + return 0; +} +EXPORT_SYMBOL_GPL(tpm_buf_init_2b); + void tpm_buf_destroy(struct tpm_buf *buf) { free_page((unsigned long)buf->data); } EXPORT_SYMBOL_GPL(tpm_buf_destroy); +static void *tpm_buf_data(struct tpm_buf *buf) +{ + if (buf->flags & TPM_BUF_2B) + return buf->data + TPM_HEADER_SIZE; + return buf->data; +} + u32 tpm_buf_length(struct tpm_buf *buf) { struct tpm_header *head = (struct tpm_header *)buf->data; + u32 len; - return be32_to_cpu(head->length); + len = be32_to_cpu(head->length); + if (buf->flags & TPM_BUF_2B) + len -= sizeof(*head); + return len; } EXPORT_SYMBOL_GPL(tpm_buf_length); @@ -56,7 +98,7 @@ void tpm_buf_append(struct tpm_buf *buf, unsigned int new_len) { struct tpm_header *head = (struct tpm_header *) buf->data; - u32 len = tpm_buf_length(buf); + u32 len = be32_to_cpu(head->length); /* Return silently if overflow has already happened. */ if (buf->flags & TPM_BUF_OVERFLOW) @@ -94,3 +136,22 @@ void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value) tpm_buf_append(buf, (u8 *) &value2, 4); } EXPORT_SYMBOL_GPL(tpm_buf_append_u32); + +static void tpm_buf_reset_int(struct tpm_buf *buf) +{ + struct tpm_header *head; + + head = (struct tpm_header *)buf->data; + head->length = cpu_to_be32(sizeof(*head)); +} + +void tpm_buf_append_2b(struct tpm_buf *buf, struct tpm_buf *tpm2b) +{ + u16 len = tpm_buf_length(tpm2b); + + tpm_buf_append_u16(buf, len); + tpm_buf_append(buf, tpm_buf_data(tpm2b), len); + /* clear the buf for reuse */ + tpm_buf_reset_int(tpm2b); +} +EXPORT_SYMBOL_GPL(tpm_buf_append_2b); diff --git a/include/linux/tpm.h b/include/linux/tpm.h index 150b39b6190e..f2d4dab6d832 100644 --- a/include/linux/tpm.h +++ b/include/linux/tpm.h @@ -300,6 +300,7 @@ struct tpm_header { enum tpm_buf_flags { TPM_BUF_OVERFLOW = BIT(0), + TPM_BUF_2B = BIT(1), }; struct tpm_buf { @@ -324,6 +325,7 @@ struct tpm2_hash { int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal); +int tpm_buf_init_2b(struct tpm_buf *buf); void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal); void tpm_buf_destroy(struct tpm_buf *buf); u32 tpm_buf_length(struct tpm_buf *buf); @@ -332,6 +334,7 @@ void tpm_buf_append(struct tpm_buf *buf, const unsigned char *new_data, void tpm_buf_append_u8(struct tpm_buf *buf, const u8 value); void tpm_buf_append_u16(struct tpm_buf *buf, const u16 value); void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value); +void tpm_buf_append_2b(struct tpm_buf *buf, struct tpm_buf *tpm2b); /* * Check if TPM device is in the firmware upgrade mode. From patchwork Fri Dec 9 16:06:03 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 13069946 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 72AF3C4332F for ; Fri, 9 Dec 2022 16:08:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229649AbiLIQIi (ORCPT ); Fri, 9 Dec 2022 11:08:38 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53732 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229634AbiLIQIh (ORCPT ); Fri, 9 Dec 2022 11:08:37 -0500 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [IPv6:2607:fcd0:100:8a00::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BB08E2AD3; Fri, 9 Dec 2022 08:08:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1670602116; bh=9alCt9sYrJcIcOuKqquVluEHMVh9XpoaIC4jh4q33MQ=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References:From; b=cngxIJvfAQcFEacNQjdVavqUdQq88Z32nSFCEogasmkD7kWZjN1YIbVMEmUj56+yt c87dXINuKmu4XB9IM+TqcHSxNQKicgRLSCtTyVl0vsmaOKf00bl0ZPlhrOGbepNabc SUvx8Oda4E+RCChPlQ2lRZCnHQ/wpDdyqUiXXdF0= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 421CB1286318; Fri, 9 Dec 2022 11:08:36 -0500 (EST) Received: from bedivere.hansenpartnership.com ([127.0.0.1]) by localhost (bedivere.hansenpartnership.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 8wpl4B6vd4Zt; Fri, 9 Dec 2022 11:08:36 -0500 (EST) Received: from lingrow.int.hansenpartnership.com (unknown [153.66.160.227]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id AFAAA1286316; Fri, 9 Dec 2022 11:08:35 -0500 (EST) From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Ard Biesheuvel , Jarkko Sakkinen , keyrings@vger.kernel.org Subject: [PATCH 03/11] tpm: add cursor based buffer functions for response parsing Date: Fri, 9 Dec 2022 11:06:03 -0500 Message-Id: <20221209160611.30207-4-James.Bottomley@HansenPartnership.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20221209160611.30207-1-James.Bottomley@HansenPartnership.com> References: <20221209160611.30207-1-James.Bottomley@HansenPartnership.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: keyrings@vger.kernel.org It's very convenient when parsing responses to have a cursor you simply move over the response extracting the data. Add such cursor functions for the TPM unsigned integer types. Signed-off-by: James Bottomley --- drivers/char/tpm/tpm-buf.c | 29 +++++++++++++++++++++++++++++ include/linux/tpm.h | 3 +++ 2 files changed, 32 insertions(+) diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c index f1d48f22d4b4..046b00bf7a81 100644 --- a/drivers/char/tpm/tpm-buf.c +++ b/drivers/char/tpm/tpm-buf.c @@ -7,6 +7,8 @@ #include #include +#include + static int __tpm_buf_init(struct tpm_buf *buf) { buf->data = (u8 *)__get_free_page(GFP_KERNEL); @@ -155,3 +157,30 @@ void tpm_buf_append_2b(struct tpm_buf *buf, struct tpm_buf *tpm2b) tpm_buf_reset_int(tpm2b); } EXPORT_SYMBOL_GPL(tpm_buf_append_2b); + +/* functions for unmarshalling data and moving the cursor */ +u8 tpm_get_inc_u8(const u8 **ptr) +{ + return *((*ptr)++); +} +EXPORT_SYMBOL_GPL(tpm_get_inc_u8); + +u16 tpm_get_inc_u16(const u8 **ptr) +{ + u16 val; + + val = get_unaligned_be16(*ptr); + *ptr += sizeof(val); + return val; +} +EXPORT_SYMBOL_GPL(tpm_get_inc_u16); + +u32 tpm_get_inc_u32(const u8 **ptr) +{ + u32 val; + + val = get_unaligned_be32(*ptr); + *ptr += sizeof(val); + return val; +} +EXPORT_SYMBOL_GPL(tpm_get_inc_u32); diff --git a/include/linux/tpm.h b/include/linux/tpm.h index f2d4dab6d832..f7cff1d114b0 100644 --- a/include/linux/tpm.h +++ b/include/linux/tpm.h @@ -335,6 +335,9 @@ void tpm_buf_append_u8(struct tpm_buf *buf, const u8 value); void tpm_buf_append_u16(struct tpm_buf *buf, const u16 value); void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value); void tpm_buf_append_2b(struct tpm_buf *buf, struct tpm_buf *tpm2b); +u8 tpm_get_inc_u8(const u8 **ptr); +u16 tpm_get_inc_u16(const u8 **ptr); +u32 tpm_get_inc_u32(const u8 **ptr); /* * Check if TPM device is in the firmware upgrade mode. From patchwork Fri Dec 9 16:06:04 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 13069947 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5D093C4332F for ; Fri, 9 Dec 2022 16:08:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229626AbiLIQI4 (ORCPT ); Fri, 9 Dec 2022 11:08:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53766 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229478AbiLIQIz (ORCPT ); Fri, 9 Dec 2022 11:08:55 -0500 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [IPv6:2607:fcd0:100:8a00::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 485995FBD; Fri, 9 Dec 2022 08:08:54 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1670602133; bh=qofRxaNJD3RRJqDlfi5G8exduyfqEZhmC9bEyj3GaRw=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References:From; b=hWhQDhHbaWRr76RzGFDbdQPPNx3/HiQMTRTgf1gaN34GjgCG/wxz0rCCHn4IKHlJI 3Vt22Jzp7bBqL61kZa/MfQfVUs9fIMjOwsoZPCBsFz5S75urhxnSJWHjmib7l6MXin lUnGTLTlsN8gvVMknKAA35DM/n1cY9Kzqt0YwI/g= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id BD94C128631F; Fri, 9 Dec 2022 11:08:53 -0500 (EST) Received: from bedivere.hansenpartnership.com ([127.0.0.1]) by localhost (bedivere.hansenpartnership.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id m_2GeTIuwY8p; Fri, 9 Dec 2022 11:08:53 -0500 (EST) Received: from lingrow.int.hansenpartnership.com (unknown [153.66.160.227]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 2E9B1128631C; Fri, 9 Dec 2022 11:08:53 -0500 (EST) From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Ard Biesheuvel , Jarkko Sakkinen , keyrings@vger.kernel.org Subject: [PATCH 04/11] tpm: add buffer function to point to returned parameters Date: Fri, 9 Dec 2022 11:06:04 -0500 Message-Id: <20221209160611.30207-5-James.Bottomley@HansenPartnership.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20221209160611.30207-1-James.Bottomley@HansenPartnership.com> References: <20221209160611.30207-1-James.Bottomley@HansenPartnership.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: keyrings@vger.kernel.org Introducing encryption sessions changes where the return parameters are located in the buffer because if a return session is present they're 4 bytes beyond the header with those 4 bytes showing the parameter length. If there is no return session, then they're in the usual place immediately after the header. The tpm_buf_parameters() encapsulates this calculation and should be used everywhere &buf.data[TPM_HEADER_SIZE] is used now Signed-off-by: James Bottomley --- drivers/char/tpm/tpm-buf.c | 10 ++++++++++ include/linux/tpm.h | 2 ++ 2 files changed, 12 insertions(+) diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c index 046b00bf7a81..b054aa2fc84b 100644 --- a/drivers/char/tpm/tpm-buf.c +++ b/drivers/char/tpm/tpm-buf.c @@ -184,3 +184,13 @@ u32 tpm_get_inc_u32(const u8 **ptr) return val; } EXPORT_SYMBOL_GPL(tpm_get_inc_u32); + +u8 *tpm_buf_parameters(struct tpm_buf *buf) +{ + int offset = TPM_HEADER_SIZE; + + if (tpm_buf_tag(buf) == TPM2_ST_SESSIONS) + offset += 4; + + return &buf->data[offset]; +} diff --git a/include/linux/tpm.h b/include/linux/tpm.h index f7cff1d114b0..fa8d1f932c0f 100644 --- a/include/linux/tpm.h +++ b/include/linux/tpm.h @@ -339,6 +339,8 @@ u8 tpm_get_inc_u8(const u8 **ptr); u16 tpm_get_inc_u16(const u8 **ptr); u32 tpm_get_inc_u32(const u8 **ptr); +u8 *tpm_buf_parameters(struct tpm_buf *buf); + /* * Check if TPM device is in the firmware upgrade mode. */ From patchwork Fri Dec 9 16:06:05 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 13069956 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 28254C4332F for ; Fri, 9 Dec 2022 16:09:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229703AbiLIQJX (ORCPT ); Fri, 9 Dec 2022 11:09:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53858 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229468AbiLIQJV (ORCPT ); Fri, 9 Dec 2022 11:09:21 -0500 X-Greylist: delayed 67 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Fri, 09 Dec 2022 08:09:18 PST Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [96.44.175.130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4155D6277; Fri, 9 Dec 2022 08:09:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1670602157; bh=SACuZ9qQZKFkIBEj5nHX9mpXGYN9nESZN0qGMbrT3zI=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References:From; b=WAI0Q4XJqH6gwOseZhyBSYync/4JuGdOsZ4hZ3bsx8Jm+3MTeuIhOfz2kpzeMbtZm MtuV3Dn4sQpmxnMhgBuSVNBSoU/FQ68VAFAcx1sBmdgKIqID9lSbRuuCKR70rbRc7r QQwiPm89d3Ra6aPsDQDbyT7ClUFSsMs9b5Is4+og= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id F0B691281045; Fri, 9 Dec 2022 11:09:17 -0500 (EST) Received: from bedivere.hansenpartnership.com ([127.0.0.1]) by localhost (bedivere.hansenpartnership.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id AGWXrmwOh_sM; Fri, 9 Dec 2022 11:09:17 -0500 (EST) Received: from lingrow.int.hansenpartnership.com (unknown [153.66.160.227]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 6555112803C0; Fri, 9 Dec 2022 11:09:17 -0500 (EST) From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Ard Biesheuvel , Jarkko Sakkinen , keyrings@vger.kernel.org Subject: [PATCH 05/11] tpm: export the context save and load commands Date: Fri, 9 Dec 2022 11:06:05 -0500 Message-Id: <20221209160611.30207-6-James.Bottomley@HansenPartnership.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20221209160611.30207-1-James.Bottomley@HansenPartnership.com> References: <20221209160611.30207-1-James.Bottomley@HansenPartnership.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: keyrings@vger.kernel.org The TPM2 session HMAC and encryption handling code needs to save and restore a single volatile context for the elliptic curve version of the NULL seed, so export the APIs which do this for internal use. Signed-off-by: James Bottomley --- drivers/char/tpm/tpm.h | 4 ++++ drivers/char/tpm/tpm2-space.c | 8 ++++---- 2 files changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h index 24ee4e1cc452..a5fe37977103 100644 --- a/drivers/char/tpm/tpm.h +++ b/drivers/char/tpm/tpm.h @@ -237,6 +237,10 @@ int tpm2_commit_space(struct tpm_chip *chip, struct tpm_space *space, void *buf, size_t *bufsiz); int tpm_devs_add(struct tpm_chip *chip); void tpm_devs_remove(struct tpm_chip *chip); +int tpm2_save_context(struct tpm_chip *chip, u32 handle, u8 *buf, + unsigned int buf_size, unsigned int *offset); +int tpm2_load_context(struct tpm_chip *chip, u8 *buf, + unsigned int *offset, u32 *handle); void tpm_bios_log_setup(struct tpm_chip *chip); void tpm_bios_log_teardown(struct tpm_chip *chip); diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c index ffb35f0154c1..d77ee4af9d65 100644 --- a/drivers/char/tpm/tpm2-space.c +++ b/drivers/char/tpm/tpm2-space.c @@ -68,8 +68,8 @@ void tpm2_del_space(struct tpm_chip *chip, struct tpm_space *space) kfree(space->session_buf); } -static int tpm2_load_context(struct tpm_chip *chip, u8 *buf, - unsigned int *offset, u32 *handle) +int tpm2_load_context(struct tpm_chip *chip, u8 *buf, + unsigned int *offset, u32 *handle) { struct tpm_buf tbuf; struct tpm2_context *ctx; @@ -119,8 +119,8 @@ static int tpm2_load_context(struct tpm_chip *chip, u8 *buf, return 0; } -static int tpm2_save_context(struct tpm_chip *chip, u32 handle, u8 *buf, - unsigned int buf_size, unsigned int *offset) +int tpm2_save_context(struct tpm_chip *chip, u32 handle, u8 *buf, + unsigned int buf_size, unsigned int *offset) { struct tpm_buf tbuf; unsigned int body_size; From patchwork Fri Dec 9 16:06:06 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 13069957 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5F60BC4332F for ; Fri, 9 Dec 2022 16:09:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229478AbiLIQJp (ORCPT ); Fri, 9 Dec 2022 11:09:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53960 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229468AbiLIQJo (ORCPT ); Fri, 9 Dec 2022 11:09:44 -0500 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [IPv6:2607:fcd0:100:8a00::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F38FF616E; Fri, 9 Dec 2022 08:09:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1670602180; bh=BLkRNRZXbW+wXebslX8Lr2ZFAcq5aoPgfs6PVOnYQFs=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References:From; b=dXTilDe3GpupZVTSDFASRS9pVq7AdKshl9Hemeszjokagp0kdA5hFKrjNIlItnM24 +hdbNttWgdp8mxo+xl1bE9PjAnE8MIhQboYFG682ilT3zyONF6kULgC3XKRGfLHXvF hVlStRWtm+IxXwXcQi8VjNHCtH70ZCsuiO+Mt+go= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id B45E41281045; Fri, 9 Dec 2022 11:09:40 -0500 (EST) Received: from bedivere.hansenpartnership.com ([127.0.0.1]) by localhost (bedivere.hansenpartnership.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id T3l5cIkMFnjF; Fri, 9 Dec 2022 11:09:40 -0500 (EST) Received: from lingrow.int.hansenpartnership.com (unknown [153.66.160.227]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 036DE12803C0; Fri, 9 Dec 2022 11:09:39 -0500 (EST) From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Ard Biesheuvel , Jarkko Sakkinen , keyrings@vger.kernel.org Subject: [PATCH 06/11] tpm: Add full HMAC and encrypt/decrypt session handling code Date: Fri, 9 Dec 2022 11:06:06 -0500 Message-Id: <20221209160611.30207-7-James.Bottomley@HansenPartnership.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20221209160611.30207-1-James.Bottomley@HansenPartnership.com> References: <20221209160611.30207-1-James.Bottomley@HansenPartnership.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: keyrings@vger.kernel.org Add true session based HMAC authentication plus parameter decryption and response encryption using AES. The basic design is to segregate all the nasty crypto, hash and hmac code into tpm2-sessions.c and export a usable API. The API first of all starts off by gaining a session with tpm2_start_auth_session() Which initiates a session with the TPM and allocates an opaque tpm2_auth structure to handle the session parameters. Then the use is simply: * tpm_buf_append_name() in place of the tpm_buf_append_u32 for the handles * tpm_buf_append_hmac_session() where tpm2_append_auth() would go * tpm_buf_fill_hmac_session() called after the entire command buffer is finished but before tpm_transmit_cmd() is called which computes the correct HMAC and places it in the command at the correct location. Finally, after tpm_transmit_cmd() is called, tpm_buf_check_hmac_response() is called to check that the returned HMAC matched and collect the new state for the next use of the session, if any. The features of the session is controlled by the session attributes set in tpm_buf_append_hmac_session(). If TPM2_SA_CONTINUE_SESSION is not specified, the session will be flushed and the tpm2_auth structure freed in tpm_buf_check_hmac_response(); otherwise the session may be used again. Parameter encryption is specified by or'ing the flag TPM2_SA_DECRYPT and response encryption by or'ing the flag TPM2_SA_ENCRYPT. the various encryptions will be taken care of by tpm_buf_fill_hmac_session() and tpm_buf_check_hmac_response() respectively. To get all of this to work securely, the Kernel needs a primary key to encrypt the session salt to, so an EC key from the NULL seed is derived and its context saved in the tpm_chip structure. The context is loaded on demand into an available volatile handle when tpm_start_auth_session() is called, but is flushed before that function exits to conserve handles. Signed-off-by: James Bottomley Reviewed-by: Ard Biesheuvel # crypto API parts --- drivers/char/tpm/Kconfig | 13 + drivers/char/tpm/Makefile | 1 + drivers/char/tpm/tpm-buf.c | 1 + drivers/char/tpm/tpm.h | 10 + drivers/char/tpm/tpm2-cmd.c | 5 + drivers/char/tpm/tpm2-sessions.c | 1199 ++++++++++++++++++++++++++++++ include/linux/tpm.h | 160 ++++ 7 files changed, 1389 insertions(+) create mode 100644 drivers/char/tpm/tpm2-sessions.c diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig index 927088b2c3d3..74bd174f1a7b 100644 --- a/drivers/char/tpm/Kconfig +++ b/drivers/char/tpm/Kconfig @@ -9,6 +9,9 @@ menuconfig TCG_TPM imply SECURITYFS select CRYPTO select CRYPTO_HASH_INFO + select CRYPTO_ECDH + select CRYPTO_AES + select CRYPTO_CFB help If you have a TPM security chip in your system, which implements the Trusted Computing Group's specification, @@ -27,6 +30,16 @@ menuconfig TCG_TPM if TCG_TPM +config TPM_BUS_SECURITY + bool "Use secure transactions on the TPM bus" + default y + help + Setting this causes us to deploy a tamper resistent scheme + for communicating with the TPM to prevent or detect bus + snooping and iterposer attacks like TPM Genie. Saying Y here + adds some encryption overhead to all kernel to TPM + transactions. + config HW_RANDOM_TPM bool "TPM HW Random Number Generator support" depends on TCG_TPM && HW_RANDOM && !(TCG_TPM=y && HW_RANDOM=m) diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile index ad3594e383e1..10dc214aa093 100644 --- a/drivers/char/tpm/Makefile +++ b/drivers/char/tpm/Makefile @@ -17,6 +17,7 @@ tpm-y += eventlog/tpm1.o tpm-y += eventlog/tpm2.o tpm-y += tpm-buf.o +tpm-$(CONFIG_TPM_BUS_SECURITY) += tpm2-sessions.o tpm-$(CONFIG_ACPI) += tpm_ppi.o eventlog/acpi.o tpm-$(CONFIG_EFI) += eventlog/efi.o tpm-$(CONFIG_OF) += eventlog/of.o diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c index b054aa2fc84b..fe3320731217 100644 --- a/drivers/char/tpm/tpm-buf.c +++ b/drivers/char/tpm/tpm-buf.c @@ -27,6 +27,7 @@ void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal) head->tag = cpu_to_be16(tag); head->length = cpu_to_be32(sizeof(*head)); head->ordinal = cpu_to_be32(ordinal); + buf->handles = 0; } EXPORT_SYMBOL_GPL(tpm_buf_reset); diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h index a5fe37977103..b3eb0f31bfd9 100644 --- a/drivers/char/tpm/tpm.h +++ b/drivers/char/tpm/tpm.h @@ -246,4 +246,14 @@ void tpm_bios_log_setup(struct tpm_chip *chip); void tpm_bios_log_teardown(struct tpm_chip *chip); int tpm_dev_common_init(void); void tpm_dev_common_exit(void); + +#ifdef CONFIG_TPM_BUS_SECURITY +int tpm2_sessions_init(struct tpm_chip *chip); +#else +static inline int tpm2_sessions_init(struct tpm_chip *chip) +{ + return 0; +} +#endif + #endif diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c index 65d03867e114..056dad3dd5c9 100644 --- a/drivers/char/tpm/tpm2-cmd.c +++ b/drivers/char/tpm/tpm2-cmd.c @@ -759,6 +759,11 @@ int tpm2_auto_startup(struct tpm_chip *chip) rc = 0; } + if (rc) + goto out; + + rc = tpm2_sessions_init(chip); + out: /* * Infineon TPM in field upgrade mode will return no data for the number diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c new file mode 100644 index 000000000000..89dd9494bf9a --- /dev/null +++ b/drivers/char/tpm/tpm2-sessions.c @@ -0,0 +1,1199 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Copyright (C) 2018 James.Bottomley@HansenPartnership.com + * + * Cryptographic helper routines for handling TPM2 sessions for + * authorization HMAC and request response encryption. + * + * The idea is to ensure that every TPM command is HMAC protected by a + * session, meaning in-flight tampering would be detected and in + * addition all sensitive inputs and responses should be encrypted. + * + * The basic way this works is to use a TPM feature called salted + * sessions where a random secret used in session construction is + * encrypted to the public part of a known TPM key. The problem is we + * have no known keys, so initially a primary Elliptic Curve key is + * derived from the NULL seed (we use EC because most TPMs generate + * these keys much faster than RSA ones). The curve used is NIST_P256 + * because that's now mandated to be present in 'TCG TPM v2.0 + * Provisioning Guidance' + * + * Threat problems: the initial TPM2_CreatePrimary is not (and cannot + * be) session protected, so a clever Man in the Middle could return a + * public key they control to this command and from there intercept + * and decode all subsequent session based transactions. The kernel + * cannot mitigate this threat but, after boot, userspace can get + * proof this has not happened by asking the TPM to certify the NULL + * key. This certification would chain back to the TPM Endorsement + * Certificate and prove the NULL seed primary had not been tampered + * with and thus all sessions must have been cryptographically secure. + * To assist with this, the initial NULL seed public key name is made + * available in a sysfs file. + * + * Use of these functions: + * + * The design is all the crypto, hash and hmac gunk is confined in this + * file and never needs to be seen even by the kernel internal user. To + * the user there's an init function tpm2_sessions_init() that needs to + * be called once per TPM which generates the NULL seed primary key. + * + * Then there are six usage functions: + * + * tpm2_start_auth_session() which allocates the opaque auth structure + * and gets a session from the TPM. This must be called before + * any of the following functions. The session is protected by a + * session_key which is derived from a random salt value + * encrypted to the NULL seed. + * tpm2_end_auth_session() kills the session and frees the resources. + * Under normal operation this function is done by + * tpm_buf_check_hmac_response(), so this is only to be used on + * error legs where the latter is not executed. + * tpm_buf_append_name() to add a handle to the buffer. This must be + * used in place of the usual tpm_buf_append_u32() for adding + * handles because handles have to be processed specially when + * calculating the HMAC. In particular, for NV, volatile and + * permanent objects you now need to provide the name. + * tpm_buf_append_hmac_session() which appends the hmac session to the + * buf in the same way tpm_buf_append_auth does(). + * tpm_buf_fill_hmac_session() This calculates the correct hash and + * places it in the buffer. It must be called after the complete + * command buffer is finalized so it can fill in the correct HMAC + * based on the parameters. + * tpm_buf_check_hmac_response() which checks the session response in + * the buffer and calculates what it should be. If there's a + * mismatch it will log a warning and return an error. If + * tpm_buf_append_hmac_session() did not specify + * TPM_SA_CONTINUE_SESSION then the session will be closed (if it + * hasn't been consumed) and the auth structure freed. + */ + +#include "tpm.h" + +#include +#include + +#include + +#include +#include +#include +#include +#include +#include + +/* if you change to AES256, you only need change this */ +#define AES_KEYBYTES AES_KEYSIZE_128 + +#define AES_KEYBITS (AES_KEYBYTES*8) +#define AUTH_MAX_NAMES 3 + +/* + * This is the structure that carries all the auth information (like + * session handle, nonces, session key and auth) from use to use it is + * designed to be opaque to anything outside. + */ +struct tpm2_auth { + u32 handle; + /* + * This has two meanings: before tpm_buf_fill_hmac_session() + * it marks the offset in the buffer of the start of the + * sessions (i.e. after all the handles). Once the buffer has + * been filled it markes the session number of our auth + * session so we can find it again in the response buffer. + * + * The two cases are distinguished because the first offset + * must always be greater than TPM_HEADER_SIZE and the second + * must be less than or equal to 5. + */ + u32 session; + /* + * the size here is variable and set by the size of our_nonce + * which must be between 16 and the name hash length. we set + * the maximum sha256 size for the greatest protection + */ + u8 our_nonce[SHA256_DIGEST_SIZE]; + u8 tpm_nonce[SHA256_DIGEST_SIZE]; + /* + * the salt is only used across the session command/response + * after that it can be used as a scratch area + */ + union { + u8 salt[EC_PT_SZ]; + /* scratch for key + IV */ + u8 scratch[AES_KEYBYTES + AES_BLOCK_SIZE]; + }; + /* + * the session key and passphrase are the same size as the + * name digest (sha256 again). The session key is constant + * for the use of the session and the passphrase can change + * with every invocation. + * + * Note: these fields must be adjacent and in this order + * because several HMAC/KDF schemes use the combination of the + * session_key and passphrase. + */ + u8 session_key[SHA256_DIGEST_SIZE]; + u8 passphrase[SHA256_DIGEST_SIZE]; + int passphraselen; + /* saved session attributes */ + u8 attrs; + __be32 ordinal; + struct crypto_sync_skcipher *aes; + struct tpm_chip *chip; + /* 3 names of handles: name_h is handle, name is name of handle */ + u32 name_h[AUTH_MAX_NAMES]; + u8 name[AUTH_MAX_NAMES][2 + SHA256_DIGEST_SIZE]; +}; + +/* + * this is our static crypto shash. This is possible because the hash + * is multi-threaded and all the state stored in the desc + */ +static struct crypto_shash *sha256_hash; + +/* + * It turns out the crypto hmac(sha256) is hard for us to consume + * because it assumes a fixed key and the TPM seems to change the key + * on every operation, so we weld the hmac init and final functions in + * here to give it the same usage characteristics as a regular hash + */ +static void hmac_init(struct shash_desc *desc, u8 *key, int keylen) +{ + u8 pad[SHA256_BLOCK_SIZE]; + int i; + + desc->tfm = sha256_hash; + crypto_shash_init(desc); + for (i = 0; i < sizeof(pad); i++) { + if (i < keylen) + pad[i] = key[i]; + else + pad[i] = 0; + pad[i] ^= HMAC_IPAD_VALUE; + } + crypto_shash_update(desc, pad, sizeof(pad)); +} + +static void hmac_final(struct shash_desc *desc, u8 *key, int keylen, u8 *out) +{ + u8 pad[SHA256_BLOCK_SIZE]; + int i; + + for (i = 0; i < sizeof(pad); i++) { + if (i < keylen) + pad[i] = key[i]; + else + pad[i] = 0; + pad[i] ^= HMAC_OPAD_VALUE; + } + + /* collect the final hash; use out as temporary storage */ + crypto_shash_final(desc, out); + + /* reuse the desc */ + crypto_shash_init(desc); + crypto_shash_update(desc, pad, sizeof(pad)); + crypto_shash_update(desc, out, SHA256_DIGEST_SIZE); + crypto_shash_final(desc, out); +} + +/* + * assume hash sha256 and nonces u, v of size SHA256_DIGEST_SIZE but + * otherwise standard KDFa. Note output is in bytes not bits. + */ +static void KDFa(u8 *key, int keylen, const char *label, u8 *u, + u8 *v, int bytes, u8 *out) +{ + u32 counter; + const __be32 bits = cpu_to_be32(bytes * 8); + + for (counter = 1; bytes > 0; bytes -= SHA256_DIGEST_SIZE, counter++, + out += SHA256_DIGEST_SIZE) { + SHASH_DESC_ON_STACK(desc, sha256_hash); + __be32 c = cpu_to_be32(counter); + + hmac_init(desc, key, keylen); + crypto_shash_update(desc, (u8 *)&c, sizeof(c)); + crypto_shash_update(desc, label, strlen(label)+1); + crypto_shash_update(desc, u, SHA256_DIGEST_SIZE); + crypto_shash_update(desc, v, SHA256_DIGEST_SIZE); + crypto_shash_update(desc, (u8 *)&bits, sizeof(bits)); + hmac_final(desc, key, keylen, out); + } +} + +/* + * Somewhat of a bastardization of the real KDFe. We're assuming + * we're working with known point sizes for the input parameters and + * the hash algorithm is fixed at sha256. Because we know that the + * point size is 32 bytes like the hash size, there's no need to loop + * in this KDF. + */ +static void KDFe(u8 z[EC_PT_SZ], const char *str, u8 *pt_u, u8 *pt_v, + u8 *keyout) +{ + SHASH_DESC_ON_STACK(desc, sha256_hash); + /* + * this should be an iterative counter, but because we know + * we're only taking 32 bytes for the point using a sha256 + * hash which is also 32 bytes, there's only one loop + */ + __be32 c = cpu_to_be32(1); + + desc->tfm = sha256_hash; + + crypto_shash_init(desc); + /* counter (BE) */ + crypto_shash_update(desc, (u8 *)&c, sizeof(c)); + /* secret value */ + crypto_shash_update(desc, z, EC_PT_SZ); + /* string including trailing zero */ + crypto_shash_update(desc, str, strlen(str)+1); + crypto_shash_update(desc, pt_u, EC_PT_SZ); + crypto_shash_update(desc, pt_v, EC_PT_SZ); + crypto_shash_final(desc, keyout); +} + +static void tpm_buf_append_salt(struct tpm_buf *buf, struct tpm_chip *chip, + struct tpm2_auth *auth) +{ + struct crypto_kpp *kpp; + struct kpp_request *req; + struct scatterlist s[2], d[1]; + struct ecdh p = {0}; + u8 encoded_key[EC_PT_SZ], *x, *y; + unsigned int buf_len; + u8 *secret; + + secret = kmalloc(EC_PT_SZ, GFP_KERNEL); + if (!secret) + return; + + /* secret is two sized points */ + tpm_buf_append_u16(buf, (EC_PT_SZ + 2)*2); + /* + * we cheat here and append uninitialized data to form + * the points. All we care about is getting the two + * co-ordinate pointers, which will be used to overwrite + * the uninitialized data + */ + tpm_buf_append_u16(buf, EC_PT_SZ); + x = &buf->data[tpm_buf_length(buf)]; + tpm_buf_append(buf, encoded_key, EC_PT_SZ); + tpm_buf_append_u16(buf, EC_PT_SZ); + y = &buf->data[tpm_buf_length(buf)]; + tpm_buf_append(buf, encoded_key, EC_PT_SZ); + sg_init_table(s, 2); + sg_set_buf(&s[0], x, EC_PT_SZ); + sg_set_buf(&s[1], y, EC_PT_SZ); + + kpp = crypto_alloc_kpp("ecdh-nist-p256", CRYPTO_ALG_INTERNAL, 0); + if (IS_ERR(kpp)) { + dev_err(&chip->dev, "crypto ecdh allocation failed\n"); + return; + } + + buf_len = crypto_ecdh_key_len(&p); + if (sizeof(encoded_key) < buf_len) { + dev_err(&chip->dev, "salt buffer too small needs %d\n", + buf_len); + goto out; + } + crypto_ecdh_encode_key(encoded_key, buf_len, &p); + /* this generates a random private key */ + crypto_kpp_set_secret(kpp, encoded_key, buf_len); + + /* salt is now the public point of this private key */ + req = kpp_request_alloc(kpp, GFP_KERNEL); + if (!req) + goto out; + kpp_request_set_input(req, NULL, 0); + kpp_request_set_output(req, s, EC_PT_SZ*2); + crypto_kpp_generate_public_key(req); + /* + * we're not done: now we have to compute the shared secret + * which is our private key multiplied by the tpm_key public + * point, we actually only take the x point and discard the y + * point and feed it through KDFe to get the final secret salt + */ + sg_set_buf(&s[0], chip->ec_point_x, EC_PT_SZ); + sg_set_buf(&s[1], chip->ec_point_y, EC_PT_SZ); + kpp_request_set_input(req, s, EC_PT_SZ*2); + sg_init_one(d, secret, EC_PT_SZ); + kpp_request_set_output(req, d, EC_PT_SZ); + crypto_kpp_compute_shared_secret(req); + kpp_request_free(req); + + /* pass the shared secret through KDFe for salt */ + KDFe(secret, "SECRET", x, chip->ec_point_x, auth->salt); + out: + crypto_free_kpp(kpp); +} + +/** + * tpm_buf_append_hmac_session() append a TPM session element + * @buf: The buffer to be appended + * @auth: the auth structure allocated by tpm2_start_auth_session() + * @attributes: The session attributes + * @passphrase: The session authority (NULL if none) + * @passphraselen: The length of the session authority (0 if none) + * + * This fills in a session structure in the TPM command buffer, except + * for the HMAC which cannot be computed until the command buffer is + * complete. The type of session is controlled by the @attributes, + * the main ones of which are TPM2_SA_CONTINUE_SESSION which means the + * session won't terminate after tpm_buf_check_hmac_response(), + * TPM2_SA_DECRYPT which means this buffers first parameter should be + * encrypted with a session key and TPM2_SA_ENCRYPT, which means the + * response buffer's first parameter needs to be decrypted (confusing, + * but the defines are written from the point of view of the TPM). + * + * Any session appended by this command must be finalized by calling + * tpm_buf_fill_hmac_session() otherwise the HMAC will be incorrect + * and the TPM will reject the command. + * + * As with most tpm_buf operations, success is assumed because failure + * will be caused by an incorrect programming model and indicated by a + * kernel message. + */ +void tpm_buf_append_hmac_session(struct tpm_buf *buf, struct tpm2_auth *auth, + u8 attributes, u8 *passphrase, + int passphraselen) +{ + u8 nonce[SHA256_DIGEST_SIZE]; + u32 len; + + /* + * The Architecture Guide requires us to strip trailing zeros + * before computing the HMAC + */ + while (passphrase && passphraselen > 0 + && passphrase[passphraselen - 1] == '\0') + passphraselen--; + + auth->attrs = attributes; + auth->passphraselen = passphraselen; + if (passphraselen) + memcpy(auth->passphrase, passphrase, passphraselen); + + if (auth->session != tpm_buf_length(buf)) { + /* we're not the first session */ + len = get_unaligned_be32(&buf->data[auth->session]); + if (4 + len + auth->session != tpm_buf_length(buf)) { + WARN(1, "session length mismatch, cannot append"); + return; + } + + /* add our new session */ + len += 9 + 2 * SHA256_DIGEST_SIZE; + put_unaligned_be32(len, &buf->data[auth->session]); + } else { + tpm_buf_append_u32(buf, 9 + 2 * SHA256_DIGEST_SIZE); + } + + /* random number for our nonce */ + get_random_bytes(nonce, sizeof(nonce)); + memcpy(auth->our_nonce, nonce, sizeof(nonce)); + tpm_buf_append_u32(buf, auth->handle); + /* our new nonce */ + tpm_buf_append_u16(buf, SHA256_DIGEST_SIZE); + tpm_buf_append(buf, nonce, SHA256_DIGEST_SIZE); + tpm_buf_append_u8(buf, auth->attrs); + /* and put a placeholder for the hmac */ + tpm_buf_append_u16(buf, SHA256_DIGEST_SIZE); + tpm_buf_append(buf, nonce, SHA256_DIGEST_SIZE); +} +EXPORT_SYMBOL(tpm_buf_append_hmac_session); + +/** + * tpm_buf_fill_hmac_session() - finalize the session HMAC + * @buf: The buffer to be appended + * @auth: the auth structure allocated by tpm2_start_auth_session() + * + * This command must not be called until all of the parameters have + * been appended to @buf otherwise the computed HMAC will be + * incorrect. + * + * This function computes and fills in the session HMAC using the + * session key and, if TPM2_SA_DECRYPT was specified, computes the + * encryption key and encrypts the first parameter of the command + * buffer with it. + * + * As with most tpm_buf operations, success is assumed because failure + * will be caused by an incorrect programming model and indicated by a + * kernel message. + */ +void tpm_buf_fill_hmac_session(struct tpm_buf *buf, struct tpm2_auth *auth) +{ + u32 cc, handles, val; + struct tpm_chip *chip = auth->chip; + int i; + struct tpm_header *head = (struct tpm_header *)buf->data; + const u8 *s, *p; + u8 *hmac = NULL; + u32 attrs; + u8 cphash[SHA256_DIGEST_SIZE]; + SHASH_DESC_ON_STACK(desc, sha256_hash); + + /* save the command code in BE format */ + auth->ordinal = head->ordinal; + + desc->tfm = sha256_hash; + + cc = be32_to_cpu(head->ordinal); + + i = tpm2_find_cc(chip, cc); + if (i < 0) { + dev_err(&chip->dev, "Command 0x%x not found in TPM\n", cc); + return; + } + attrs = chip->cc_attrs_tbl[i]; + + handles = (attrs >> TPM2_CC_ATTR_CHANDLES) & GENMASK(2, 0); + + s = &buf->data[TPM_HEADER_SIZE]; + /* + * just check the names, it's easy to make mistakes. This + * would happen if someone added a handle via + * tpm_buf_append_u32() instead of tpm_buf_append_name() + */ + for (i = 0; i < handles; i++) { + u32 handle = tpm_get_inc_u32(&s); + + if (auth->name_h[i] != handle) { + dev_err(&chip->dev, "TPM: handle %d wrong for name\n", + i); + return; + } + } + /* point s to the start of the sessions */ + val = tpm_get_inc_u32(&s); + /* point p to the start of the parameters */ + p = s + val; + for (i = 1; s < p; i++) { + u32 handle = tpm_get_inc_u32(&s); + u16 len; + u8 a; + + /* nonce (already in auth) */ + len = tpm_get_inc_u16(&s); + s += len; + + a = *s++; + + len = tpm_get_inc_u16(&s); + if (handle == auth->handle && auth->attrs == a) { + hmac = (u8 *)s; + /* + * save our session number so we know which + * session in the response belongs to us + */ + auth->session = i; + } + + s += len; + } + if (s != p) { + dev_err(&chip->dev, "TPM session length is incorrect\n"); + return; + } + if (!hmac) { + dev_err(&chip->dev, "TPM could not find HMAC session\n"); + return; + } + + /* encrypt before HMAC */ + if (auth->attrs & TPM2_SA_DECRYPT) { + struct scatterlist sg[1]; + u16 len; + SYNC_SKCIPHER_REQUEST_ON_STACK(req, auth->aes); + DECLARE_CRYPTO_WAIT(wait); + + skcipher_request_set_sync_tfm(req, auth->aes); + skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, + crypto_req_done, &wait); + + /* need key and IV */ + KDFa(auth->session_key, SHA256_DIGEST_SIZE + + auth->passphraselen, "CFB", auth->our_nonce, + auth->tpm_nonce, AES_KEYBYTES + AES_BLOCK_SIZE, + auth->scratch); + crypto_sync_skcipher_setkey(auth->aes, auth->scratch, AES_KEYBYTES); + len = tpm_get_inc_u16(&p); + sg_init_one(sg, p, len); + skcipher_request_set_crypt(req, sg, sg, len, + auth->scratch + AES_KEYBYTES); + crypto_wait_req(crypto_skcipher_encrypt(req), &wait); + /* reset p to beginning of parameters for HMAC */ + p -= 2; + } + + crypto_shash_init(desc); + /* ordinal is already BE */ + crypto_shash_update(desc, (u8 *)&head->ordinal, sizeof(head->ordinal)); + /* add the handle names */ + for (i = 0; i < handles; i++) { + u8 mso = auth->name_h[i] >> 24; + + if (mso == 0x81 || mso == 0x80 || mso == 0x01) { + crypto_shash_update(desc, auth->name[i], + SHA256_DIGEST_SIZE + 2); + } else { + __be32 h = cpu_to_be32(auth->name_h[i]); + + crypto_shash_update(desc, (u8 *)&h, 4); + } + } + if (buf->data - s != tpm_buf_length(buf)) + crypto_shash_update(desc, s, buf->data + + tpm_buf_length(buf) - s); + crypto_shash_final(desc, cphash); + + /* now calculate the hmac */ + hmac_init(desc, auth->session_key, sizeof(auth->session_key) + + auth->passphraselen); + crypto_shash_update(desc, cphash, sizeof(cphash)); + crypto_shash_update(desc, auth->our_nonce, sizeof(auth->our_nonce)); + crypto_shash_update(desc, auth->tpm_nonce, sizeof(auth->tpm_nonce)); + crypto_shash_update(desc, &auth->attrs, 1); + hmac_final(desc, auth->session_key, sizeof(auth->session_key) + + auth->passphraselen, hmac); +} +EXPORT_SYMBOL(tpm_buf_fill_hmac_session); + +static int parse_read_public(char *name, const u8 *data) +{ + struct tpm_header *head = (struct tpm_header *)data; + u32 tot_len = be32_to_cpu(head->length); + u32 val; + + data += TPM_HEADER_SIZE; + /* we're starting after the header so adjust the length */ + tot_len -= TPM_HEADER_SIZE; + + /* skip public */ + val = tpm_get_inc_u16(&data); + if (val > tot_len) + return -EINVAL; + data += val; + /* name */ + val = tpm_get_inc_u16(&data); + if (val != SHA256_DIGEST_SIZE + 2) + return -EINVAL; + memcpy(name, data, SHA256_DIGEST_SIZE + 2); + /* forget the rest */ + return 0; +} + +static int tpm2_readpublic(struct tpm_chip *chip, u32 handle, char *name) +{ + struct tpm_buf buf; + int rc; + + rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_READ_PUBLIC); + if (rc) + return rc; + + tpm_buf_append_u32(&buf, handle); + rc = tpm_transmit_cmd(chip, &buf, 0, "read public"); + if (rc == TPM2_RC_SUCCESS) + rc = parse_read_public(name, buf.data); + + tpm_buf_destroy(&buf); + + return rc; +} + +/** + * tpm_buf_append_name() - add a handle area to the buffer + * @buf: The buffer to be appended + * @auth: the auth structure allocated by tpm2_start_auth_session() + * @handle: The handle to be appended + * @name: The name of the handle (may be NULL) + * + * In order to compute session HMACs, we need to know the names of the + * objects pointed to by the handles. For most objects, this is simly + * the actual 4 byte handle or an empty buf (in these cases @name + * should be NULL) but for volatile objects, permanent objects and NV + * areas, the name is defined as the hash (according to the name + * algorithm which should be set to sha256) of the public area to + * which the two byte algorithm id has been appended. For these + * objects, the @name pointer should point to this. If a name is + * required but @name is NULL, then TPM2_ReadPublic() will be called + * on the handle to obtain the name. + * + * As with most tpm_buf operations, success is assumed because failure + * will be caused by an incorrect programming model and indicated by a + * kernel message. + */ +void tpm_buf_append_name(struct tpm_buf *buf, struct tpm2_auth *auth, + u32 handle, u8 *name) +{ + int slot; + u8 mso = handle >> 24; + + slot = (tpm_buf_length(buf) - TPM_HEADER_SIZE)/4; + if (slot >= AUTH_MAX_NAMES) { + dev_err(&auth->chip->dev, "TPM: too many handles\n"); + return; + } + WARN(auth->session != tpm_buf_length(buf), + "name added in wrong place\n"); + tpm_buf_append_u32(buf, handle); + auth->session += 4; + + if (mso == 0x81 || mso == 0x80 || mso == 0x01) { + if (!name) + tpm2_readpublic(auth->chip, handle, auth->name[slot]); + } else { + if (name) + dev_err(&auth->chip->dev, "TPM: Handle does not require name but one is specified\n"); + } + + auth->name_h[slot] = handle; + if (name) + memcpy(auth->name[slot], name, SHA256_DIGEST_SIZE + 2); +} +EXPORT_SYMBOL(tpm_buf_append_name); + +/** + * tpm_buf_check_hmac_response() - check the TPM return HMAC for correctness + * @buf: the original command buffer (which now contains the response) + * @auth: the auth structure allocated by tpm2_start_auth_session() + * @rc: the return code from tpm_transmit_cmd + * + * If @rc is non zero, @buf may not contain an actual return, so @rc + * is passed through as the return and the session cleaned up and + * de-allocated if required (this is required if + * TPM2_SA_CONTINUE_SESSION was not specified as a session flag). + * + * If @rc is zero, the response HMAC is computed against the returned + * @buf and matched to the TPM one in the session area. If there is a + * mismatch, an error is logged and -EINVAL returned. + * + * The reason for this is that the command issue and HMAC check + * sequence should look like: + * + * rc = tpm_transmit_cmd(...); + * rc = tpm_buf_check_hmac_response(&buf, auth, rc); + * if (rc) + * ... + * + * Which is easily layered into the current contrl flow. + * + * Returns: 0 on success or an error. + */ +int tpm_buf_check_hmac_response(struct tpm_buf *buf, struct tpm2_auth *auth, + int rc) +{ + struct tpm_header *head = (struct tpm_header *)buf->data; + struct tpm_chip *chip = auth->chip; + const u8 *s, *p; + u8 rphash[SHA256_DIGEST_SIZE]; + u32 attrs; + SHASH_DESC_ON_STACK(desc, sha256_hash); + u16 tag = be16_to_cpu(head->tag); + u32 cc = be32_to_cpu(auth->ordinal); + int parm_len, len, i, handles; + + if (auth->session >= TPM_HEADER_SIZE) { + WARN(1, "tpm session not filled correctly\n"); + goto out; + } + + if (rc != 0) + /* pass non success rc through and close the session */ + goto out; + + rc = -EINVAL; + if (tag != TPM2_ST_SESSIONS) { + dev_err(&chip->dev, "TPM: HMAC response check has no sessions tag\n"); + goto out; + } + + i = tpm2_find_cc(chip, cc); + if (i < 0) + goto out; + attrs = chip->cc_attrs_tbl[i]; + handles = (attrs >> TPM2_CC_ATTR_RHANDLE) & 1; + + /* point to area beyond handles */ + s = &buf->data[TPM_HEADER_SIZE + handles * 4]; + parm_len = tpm_get_inc_u32(&s); + p = s; + s += parm_len; + /* skip over any sessions before ours */ + for (i = 0; i < auth->session - 1; i++) { + len = tpm_get_inc_u16(&s); + s += len + 1; + len = tpm_get_inc_u16(&s); + s += len; + } + /* TPM nonce */ + len = tpm_get_inc_u16(&s); + if (s - buf->data + len > tpm_buf_length(buf)) + goto out; + if (len != SHA256_DIGEST_SIZE) + goto out; + memcpy(auth->tpm_nonce, s, len); + s += len; + attrs = *s++; + len = tpm_get_inc_u16(&s); + if (s - buf->data + len != tpm_buf_length(buf)) + goto out; + if (len != SHA256_DIGEST_SIZE) + goto out; + /* + * s points to the HMAC. now calculate comparison, beginning + * with rphash + */ + desc->tfm = sha256_hash; + crypto_shash_init(desc); + /* yes, I know this is now zero, but it's what the standard says */ + crypto_shash_update(desc, (u8 *)&head->return_code, + sizeof(head->return_code)); + /* ordinal is already BE */ + crypto_shash_update(desc, (u8 *)&auth->ordinal, sizeof(auth->ordinal)); + crypto_shash_update(desc, p, parm_len); + crypto_shash_final(desc, rphash); + + /* now calculate the hmac */ + hmac_init(desc, auth->session_key, sizeof(auth->session_key) + + auth->passphraselen); + crypto_shash_update(desc, rphash, sizeof(rphash)); + crypto_shash_update(desc, auth->tpm_nonce, sizeof(auth->tpm_nonce)); + crypto_shash_update(desc, auth->our_nonce, sizeof(auth->our_nonce)); + crypto_shash_update(desc, &auth->attrs, 1); + /* we're done with the rphash, so put our idea of the hmac there */ + hmac_final(desc, auth->session_key, sizeof(auth->session_key) + + auth->passphraselen, rphash); + if (memcmp(rphash, s, SHA256_DIGEST_SIZE) == 0) { + rc = 0; + } else { + dev_err(&auth->chip->dev, "TPM: HMAC check failed\n"); + goto out; + } + + /* now do response decryption */ + if (auth->attrs & TPM2_SA_ENCRYPT) { + struct scatterlist sg[1]; + SYNC_SKCIPHER_REQUEST_ON_STACK(req, auth->aes); + DECLARE_CRYPTO_WAIT(wait); + + skcipher_request_set_sync_tfm(req, auth->aes); + skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, + crypto_req_done, &wait); + + /* need key and IV */ + KDFa(auth->session_key, SHA256_DIGEST_SIZE + + auth->passphraselen, "CFB", auth->tpm_nonce, + auth->our_nonce, AES_KEYBYTES + AES_BLOCK_SIZE, + auth->scratch); + crypto_sync_skcipher_setkey(auth->aes, auth->scratch, AES_KEYBYTES); + len = tpm_get_inc_u16(&p); + sg_init_one(sg, p, len); + skcipher_request_set_crypt(req, sg, sg, len, + auth->scratch + AES_KEYBYTES); + crypto_wait_req(crypto_skcipher_decrypt(req), &wait); + } + + out: + if ((auth->attrs & TPM2_SA_CONTINUE_SESSION) == 0) { + /* manually close the session if it wasn't consumed */ + if (rc) + tpm2_flush_context(chip, auth->handle); + crypto_free_sync_skcipher(auth->aes); + kfree(auth); + } else { + /* reset for next use */ + auth->session = TPM_HEADER_SIZE; + } + + return rc; +} +EXPORT_SYMBOL(tpm_buf_check_hmac_response); + +/** + * tpm2_end_auth_session - kill the allocated auth session + * @auth: the auth structure allocated by tpm2_start_auth_session() + * + * ends the session started by tpm2_start_auth_session and frees all + * the resources. Under normal conditions, + * tpm_buf_check_hmac_response() will correctly end the session if + * required, so this function is only for use in error legs that will + * bypass the normal invocation of tpm_buf_check_hmac_respons(). + */ +void tpm2_end_auth_session(struct tpm2_auth *auth) +{ + tpm2_flush_context(auth->chip, auth->handle); + crypto_free_sync_skcipher(auth->aes); + kfree(auth); +} +EXPORT_SYMBOL(tpm2_end_auth_session); + +static int parse_start_auth_session(struct tpm2_auth *auth, const u8 *data) +{ + struct tpm_header *head = (struct tpm_header *)data; + u32 tot_len = be32_to_cpu(head->length); + u32 val; + + data += TPM_HEADER_SIZE; + /* we're starting after the header so adjust the length */ + tot_len -= TPM_HEADER_SIZE; + + /* should have handle plus nonce */ + if (tot_len != 4 + 2 + sizeof(auth->tpm_nonce)) + return -EINVAL; + + auth->handle = tpm_get_inc_u32(&data); + val = tpm_get_inc_u16(&data); + if (val != sizeof(auth->tpm_nonce)) + return -EINVAL; + memcpy(auth->tpm_nonce, data, sizeof(auth->tpm_nonce)); + /* now compute the session key from the nonces */ + KDFa(auth->salt, sizeof(auth->salt), "ATH", auth->tpm_nonce, + auth->our_nonce, sizeof(auth->session_key), auth->session_key); + + return 0; +} + +/** + * tpm2_start_auth_session - create a HMAC authentication session with the TPM + * @chip: the TPM chip structure to create the session with + * @authp: A pointer to an opaque tpm2_auth structure to be allocated + * + * This function loads the NULL seed from its saved context and starts + * an authentication session on the null seed, allocates a tpm2_auth + * structure to contain all the session details necessary for + * performing the HMAC, encrypt and decrypt operations, fills it in + * and returns. The NULL seed is flushed before this function returns. + * + * Return: zero on success or actual error encountered. If return is + * zero, @authp will be allocated. + */ +int tpm2_start_auth_session(struct tpm_chip *chip, struct tpm2_auth **authp) +{ + struct tpm_buf buf; + struct tpm2_auth *auth; + int rc; + unsigned int offset = 0; /* dummy offset for null seed context */ + u32 nullkey; + + auth = kmalloc(sizeof(**authp), GFP_KERNEL); + if (!auth) + return -ENOMEM; + + rc = tpm2_load_context(chip, chip->tpmkeycontext, &offset, + &nullkey); + if (rc) + return rc; + + auth->chip = chip; + auth->session = TPM_HEADER_SIZE; + + rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_START_AUTH_SESS); + if (rc) + goto out; + + /* salt key handle */ + tpm_buf_append_u32(&buf, nullkey); + /* bind key handle */ + tpm_buf_append_u32(&buf, TPM2_RH_NULL); + /* nonce caller */ + get_random_bytes(auth->our_nonce, sizeof(auth->our_nonce)); + tpm_buf_append_u16(&buf, sizeof(auth->our_nonce)); + tpm_buf_append(&buf, auth->our_nonce, sizeof(auth->our_nonce)); + + /* append encrypted salt and squirrel away unencrypted in auth */ + tpm_buf_append_salt(&buf, chip, auth); + /* session type (HMAC, audit or policy) */ + tpm_buf_append_u8(&buf, TPM2_SE_HMAC); + + /* symmetric encryption parameters */ + /* symmetric algorithm */ + tpm_buf_append_u16(&buf, TPM_ALG_AES); + /* bits for symmetric algorithm */ + tpm_buf_append_u16(&buf, AES_KEYBITS); + /* symmetric algorithm mode (must be CFB) */ + tpm_buf_append_u16(&buf, TPM_ALG_CFB); + /* hash algorithm for session */ + tpm_buf_append_u16(&buf, TPM_ALG_SHA256); + + rc = tpm_transmit_cmd(chip, &buf, 0, "start auth session"); + tpm2_flush_context(chip, nullkey); + + if (rc == TPM2_RC_SUCCESS) + rc = parse_start_auth_session(auth, buf.data); + + tpm_buf_destroy(&buf); + + if (rc) + goto out; + + auth->aes = crypto_alloc_sync_skcipher("cfb(aes)", 0, 0); + if (IS_ERR(auth->aes)) { + rc = PTR_ERR(auth->aes); + dev_err(&chip->dev, "TPM: error getting cfb(aes): %d\n", rc); + } + out: + if (rc) + kfree(auth); + else + *authp = auth; + + return rc; +} +EXPORT_SYMBOL(tpm2_start_auth_session); + +static int parse_create_primary(struct tpm_chip *chip, u8 *data, u32 *nullkey) +{ + struct tpm_header *head = (struct tpm_header *)data; + u16 len; + u32 tot_len = be32_to_cpu(head->length); + u32 val, parm_len; + const u8 *resp, *tmp; + SHASH_DESC_ON_STACK(desc, sha256_hash); + + data += TPM_HEADER_SIZE; + /* we're starting after the header so adjust the length */ + tot_len -= TPM_HEADER_SIZE; + + resp = data; + *nullkey = tpm_get_inc_u32(&resp); + parm_len = tpm_get_inc_u32(&resp); + if (parm_len + 8 > tot_len) + return -EINVAL; + len = tpm_get_inc_u16(&resp); + tmp = resp; + /* now we have the public area, compute the name of the object */ + desc->tfm = sha256_hash; + put_unaligned_be16(TPM_ALG_SHA256, chip->tpmkeyname); + crypto_shash_init(desc); + crypto_shash_update(desc, resp, len); + crypto_shash_final(desc, chip->tpmkeyname + 2); + /* validate the public key */ + val = tpm_get_inc_u16(&tmp); + /* key type (must be what we asked for) */ + if (val != TPM_ALG_ECC) + return -EINVAL; + val = tpm_get_inc_u16(&tmp); + /* name algorithm */ + if (val != TPM_ALG_SHA256) + return -EINVAL; + val = tpm_get_inc_u32(&tmp); + /* object properties */ + if (val != (TPM2_OA_NO_DA | + TPM2_OA_FIXED_TPM | + TPM2_OA_FIXED_PARENT | + TPM2_OA_SENSITIVE_DATA_ORIGIN | + TPM2_OA_USER_WITH_AUTH | + TPM2_OA_DECRYPT | + TPM2_OA_RESTRICTED)) + return -EINVAL; + /* auth policy (empty) */ + val = tpm_get_inc_u16(&tmp); + if (val != 0) + return -EINVAL; + val = tpm_get_inc_u16(&tmp); + /* symmetric key parameters */ + if (val != TPM_ALG_AES) + return -EINVAL; + val = tpm_get_inc_u16(&tmp); + /* symmetric key length */ + if (val != AES_KEYBITS) + return -EINVAL; + val = tpm_get_inc_u16(&tmp); + /* symmetric encryption scheme */ + if (val != TPM_ALG_CFB) + return -EINVAL; + val = tpm_get_inc_u16(&tmp); + /* signing scheme */ + if (val != TPM_ALG_NULL) + return -EINVAL; + val = tpm_get_inc_u16(&tmp); + /* ECC Curve */ + if (val != TPM2_ECC_NIST_P256) + return -EINVAL; + val = tpm_get_inc_u16(&tmp); + /* KDF Scheme */ + if (val != TPM_ALG_NULL) + return -EINVAL; + val = tpm_get_inc_u16(&tmp); + /* x point */ + if (val != 32) + return -EINVAL; + memcpy(chip->ec_point_x, tmp, val); + tmp += val; + val = tpm_get_inc_u16(&tmp); + if (val != 32) + return -EINVAL; + memcpy(chip->ec_point_y, tmp, val); + tmp += val; + resp += len; + /* should have exactly consumed the tpm2b public structure */ + if (tmp != resp) + return -EINVAL; + if (resp - data > parm_len) + return -EINVAL; + /* creation data (skip) */ + len = tpm_get_inc_u16(&resp); + resp += len; + if (resp - data > parm_len) + return -EINVAL; + /* creation digest (must be sha256) */ + len = tpm_get_inc_u16(&resp); + resp += len; + if (len != SHA256_DIGEST_SIZE || resp - data > parm_len) + return -EINVAL; + /* TPMT_TK_CREATION follows */ + /* tag, must be TPM_ST_CREATION (0x8021) */ + val = tpm_get_inc_u16(&resp); + if (val != TPM2_ST_CREATION || resp - data > parm_len) + return -EINVAL; + /* hierarchy (must be NULL) */ + val = tpm_get_inc_u32(&resp); + if (val != TPM2_RH_NULL || resp - data > parm_len) + return -EINVAL; + /* the ticket digest HMAC (might not be sha256) */ + len = tpm_get_inc_u16(&resp); + resp += len; + if (resp - data > parm_len) + return -EINVAL; + /* + * finally we have the name, which is a sha256 digest plus a 2 + * byte algorithm type + */ + len = tpm_get_inc_u16(&resp); + if (resp + len - data != parm_len + 8) + return -EINVAL; + if (len != SHA256_DIGEST_SIZE + 2) + return -EINVAL; + + if (memcmp(chip->tpmkeyname, resp, SHA256_DIGEST_SIZE + 2) != 0) { + printk("TPM NULL Seed name comparison failed\n"); + return -EINVAL; + } + + return 0; +} + +static int tpm2_create_primary(struct tpm_chip *chip, u32 hierarchy, u32 *handle) +{ + int rc; + struct tpm_buf buf; + struct tpm_buf template; + + rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE_PRIMARY); + if (rc) + return rc; + + rc = tpm_buf_init_2b(&template); + if (rc) { + tpm_buf_destroy(&buf); + return rc; + } + + /* + * create the template. Note: in order for userspace to + * verify the security of the system, it will have to create + * and certify this NULL primary, meaning all the template + * parameters will have to be identical, so conform exactly to + * the TCG TPM v2.0 Provisioning Guidance for the SRK ECC + * key + */ + + /* key type */ + tpm_buf_append_u16(&template, TPM_ALG_ECC); + /* name algorithm */ + tpm_buf_append_u16(&template, TPM_ALG_SHA256); + /* object properties */ + tpm_buf_append_u32(&template, TPM2_OA_NO_DA | + TPM2_OA_FIXED_TPM | + TPM2_OA_FIXED_PARENT | + TPM2_OA_SENSITIVE_DATA_ORIGIN | + TPM2_OA_USER_WITH_AUTH | + TPM2_OA_DECRYPT | + TPM2_OA_RESTRICTED); + /* sauth policy (empty) */ + tpm_buf_append_u16(&template, 0); + + /* BEGIN parameters: key specific; for ECC*/ + /* symmetric algorithm */ + tpm_buf_append_u16(&template, TPM_ALG_AES); + /* bits for symmetric algorithm */ + tpm_buf_append_u16(&template, 128); + /* algorithm mode (must be CFB) */ + tpm_buf_append_u16(&template, TPM_ALG_CFB); + /* scheme (NULL means any scheme) */ + tpm_buf_append_u16(&template, TPM_ALG_NULL); + /* ECC Curve ID */ + tpm_buf_append_u16(&template, TPM2_ECC_NIST_P256); + /* KDF Scheme */ + tpm_buf_append_u16(&template, TPM_ALG_NULL); + /* unique: key specific; for ECC it is two points */ + tpm_buf_append_u16(&template, 0); + tpm_buf_append_u16(&template, 0); + /* END parameters */ + + /* primary handle */ + tpm_buf_append_u32(&buf, hierarchy); + tpm_buf_append_empty_auth(&buf, TPM2_RS_PW); + /* sensitive create size is 4 for two empty buffers */ + tpm_buf_append_u16(&buf, 4); + /* sensitive create auth data (empty) */ + tpm_buf_append_u16(&buf, 0); + /* sensitive create sensitive data (empty) */ + tpm_buf_append_u16(&buf, 0); + /* the public template */ + tpm_buf_append_2b(&buf, &template); + tpm_buf_destroy(&template); + /* outside info (empty) */ + tpm_buf_append_u16(&buf, 0); + /* creation PCR (none) */ + tpm_buf_append_u32(&buf, 0); + + rc = tpm_transmit_cmd(chip, &buf, 0, + "attempting to create NULL primary"); + + if (rc == TPM2_RC_SUCCESS) + rc = parse_create_primary(chip, buf.data, handle); + + tpm_buf_destroy(&buf); + + return rc; +} + +int tpm2_create_null_primary(struct tpm_chip *chip) { + u32 nullkey; + int rc; + + rc = tpm2_create_primary(chip, TPM2_RH_NULL, &nullkey); + + if (rc == TPM2_RC_SUCCESS) { + unsigned int offset = 0; /* dummy offset for tpmkeycontext */ + + rc = tpm2_save_context(chip, nullkey, chip->tpmkeycontext, + sizeof(chip->tpmkeycontext), &offset); + tpm2_flush_context(chip, nullkey); + } + + return rc; +} + +int tpm2_sessions_init(struct tpm_chip *chip) +{ + int rc; + + sha256_hash = crypto_alloc_shash("sha256", 0, 0); + if (!sha256_hash) { + dev_err(&chip->dev, "TPM: failed to allocate hash\n"); + return -ENOMEM; + } + + rc = tpm2_create_null_primary(chip); + if (rc) + dev_err(&chip->dev, "TPM: security failed (NULL seed derivation): %d\n", rc); + return rc; +} +EXPORT_SYMBOL(tpm2_sessions_init); diff --git a/include/linux/tpm.h b/include/linux/tpm.h index fa8d1f932c0f..bdf19538b103 100644 --- a/include/linux/tpm.h +++ b/include/linux/tpm.h @@ -30,17 +30,28 @@ struct tpm_chip; struct trusted_key_payload; struct trusted_key_options; +/* opaque structure, holds auth session parameters like the session key */ +struct tpm2_auth; + +enum tpm2_session_types { + TPM2_SE_HMAC = 0x00, + TPM2_SE_POLICY = 0x01, + TPM2_SE_TRIAL = 0x02, +}; /* if you add a new hash to this, increment TPM_MAX_HASHES below */ enum tpm_algorithms { TPM_ALG_ERROR = 0x0000, TPM_ALG_SHA1 = 0x0004, + TPM_ALG_AES = 0x0006, TPM_ALG_KEYEDHASH = 0x0008, TPM_ALG_SHA256 = 0x000B, TPM_ALG_SHA384 = 0x000C, TPM_ALG_SHA512 = 0x000D, TPM_ALG_NULL = 0x0010, TPM_ALG_SM3_256 = 0x0012, + TPM_ALG_ECC = 0x0023, + TPM_ALG_CFB = 0x0043, }; /* @@ -49,6 +60,11 @@ enum tpm_algorithms { */ #define TPM_MAX_HASHES 5 +enum tpm2_curves { + TPM2_ECC_NONE = 0x0000, + TPM2_ECC_NIST_P256 = 0x0003, +}; + struct tpm_digest { u16 alg_id; u8 digest[TPM_MAX_DIGEST_SIZE]; @@ -116,6 +132,20 @@ struct tpm_chip_seqops { const struct seq_operations *seqops; }; +/* fixed define for the curve we use which is NIST_P256 */ +#define EC_PT_SZ 32 + +/* + * fixed define for the size of a name. This is actually HASHALG size + * plus 2, so 32 for SHA256 + */ +#define TPM2_NAME_SIZE 34 + +/* + * The maximum size for an object context + */ +#define TPM2_MAX_CONTEXT_SIZE 4096 + struct tpm_chip { struct device dev; struct device devs; @@ -170,6 +200,12 @@ struct tpm_chip { /* active locality */ int locality; + + /* details for communication security via sessions */ + u8 tpmkeycontext[TPM2_MAX_CONTEXT_SIZE]; /* context for NULL seed */ + u8 tpmkeyname[TPM2_NAME_SIZE]; /* name of NULL seed */ + u8 ec_point_x[EC_PT_SZ]; + u8 ec_point_y[EC_PT_SZ]; }; #define TPM_HEADER_SIZE 10 @@ -194,6 +230,7 @@ enum tpm2_timeouts { enum tpm2_structures { TPM2_ST_NO_SESSIONS = 0x8001, TPM2_ST_SESSIONS = 0x8002, + TPM2_ST_CREATION = 0x8021, }; /* Indicates from what layer of the software stack the error comes from */ @@ -231,6 +268,10 @@ enum tpm2_command_codes { TPM2_CC_CONTEXT_LOAD = 0x0161, TPM2_CC_CONTEXT_SAVE = 0x0162, TPM2_CC_FLUSH_CONTEXT = 0x0165, + TPM2_CC_POLICY_AUTHVALUE = 0x016B, + TPM2_CC_POLICY_COUNTER_TIMER = 0x016D, + TPM2_CC_READ_PUBLIC = 0x0173, + TPM2_CC_START_AUTH_SESS = 0x0176, TPM2_CC_VERIFY_SIGNATURE = 0x0177, TPM2_CC_GET_CAPABILITY = 0x017A, TPM2_CC_GET_RANDOM = 0x017B, @@ -243,6 +284,7 @@ enum tpm2_command_codes { }; enum tpm2_permanent_handles { + TPM2_RH_NULL = 0x40000007, TPM2_RS_PW = 0x40000009, }; @@ -306,16 +348,30 @@ enum tpm_buf_flags { struct tpm_buf { unsigned int flags; u8 *data; + u8 handles; }; enum tpm2_object_attributes { TPM2_OA_FIXED_TPM = BIT(1), + TPM2_OA_ST_CLEAR = BIT(2), TPM2_OA_FIXED_PARENT = BIT(4), + TPM2_OA_SENSITIVE_DATA_ORIGIN = BIT(5), TPM2_OA_USER_WITH_AUTH = BIT(6), + TPM2_OA_ADMIN_WITH_POLICY = BIT(7), + TPM2_OA_NO_DA = BIT(10), + TPM2_OA_ENCRYPTED_DUPLICATION = BIT(11), + TPM2_OA_RESTRICTED = BIT(16), + TPM2_OA_DECRYPT = BIT(17), + TPM2_OA_SIGN = BIT(18), }; enum tpm2_session_attributes { TPM2_SA_CONTINUE_SESSION = BIT(0), + TPM2_SA_AUDIT_EXCLUSIVE = BIT(1), + TPM2_SA_AUDIT_RESET = BIT(3), + TPM2_SA_DECRYPT = BIT(5), + TPM2_SA_ENCRYPT = BIT(6), + TPM2_SA_AUDIT = BIT(7), }; struct tpm2_hash { @@ -369,6 +425,15 @@ extern int tpm_send(struct tpm_chip *chip, void *cmd, size_t buflen); extern int tpm_get_random(struct tpm_chip *chip, u8 *data, size_t max); extern struct tpm_chip *tpm_default_chip(void); void tpm2_flush_context(struct tpm_chip *chip, u32 handle); +static inline void tpm_buf_append_empty_auth(struct tpm_buf *buf, u32 handle) +{ + /* simple authorization for empty auth */ + tpm_buf_append_u32(buf, 9); /* total length of auth */ + tpm_buf_append_u32(buf, handle); + tpm_buf_append_u16(buf, 0); /* nonce len */ + tpm_buf_append_u8(buf, 0); /* attributes */ + tpm_buf_append_u16(buf, 0); /* hmac len */ +} #else static inline int tpm_is_tpm2(struct tpm_chip *chip) { @@ -399,5 +464,100 @@ static inline struct tpm_chip *tpm_default_chip(void) { return NULL; } + +static inline void tpm_buf_append_empty_auth(struct tpm_buf *buf, u32 handle) +{ +} #endif +#ifdef CONFIG_TPM_BUS_SECURITY + +int tpm2_start_auth_session(struct tpm_chip *chip, struct tpm2_auth **authp); +void tpm_buf_append_name(struct tpm_buf *buf, struct tpm2_auth *auth, + u32 handle, u8 *name); +void tpm_buf_append_hmac_session(struct tpm_buf *buf, struct tpm2_auth *auth, + u8 attributes, u8 *passphrase, + int passphraselen); +static inline void tpm_buf_append_hmac_session_opt(struct tpm_buf *buf, + struct tpm2_auth *auth, + u8 attributes, + u8 *passphrase, + int passphraselen) +{ + tpm_buf_append_hmac_session(buf, auth, attributes, passphrase, + passphraselen); +} +void tpm_buf_fill_hmac_session(struct tpm_buf *buf, struct tpm2_auth *auth); +int tpm_buf_check_hmac_response(struct tpm_buf *buf, struct tpm2_auth *auth, + int rc); +void tpm2_end_auth_session(struct tpm2_auth *auth); +#else +#include + +static inline int tpm2_start_auth_session(struct tpm_chip *chip, + struct tpm2_auth **authp) +{ + return 0; +} +static inline void tpm2_end_auth_session(struct tpm2_auth *auth) +{ +} +static inline void tpm_buf_append_name(struct tpm_buf *buf, + struct tpm2_auth *auth, + u32 handle, u8 *name) +{ + tpm_buf_append_u32(buf, handle); + /* count the number of handles in the upper bits of flags */ + buf->handles++; +} +static inline void tpm_buf_append_hmac_session(struct tpm_buf *buf, + struct tpm2_auth *auth, + u8 attributes, u8 *passphrase, + int passphraselen) +{ + /* offset tells us where the sessions area begins */ + int offset = buf->handles * 4 + TPM_HEADER_SIZE; + u32 len = 9 + passphraselen; + if (tpm_buf_length(buf) != offset) { + /* not the first session so update the existing length */ + len += 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, passphraselen); + tpm_buf_append(buf, passphrase, passphraselen); +} +static inline void tpm_buf_append_hmac_session_opt(struct tpm_buf *buf, + struct tpm2_auth *auth, + u8 attributes, + u8 *passphrase, + int passphraselen) +{ + int offset = buf->handles * 4 + TPM_HEADER_SIZE; + struct tpm_header *head = (struct tpm_header *) buf->data; + + /* if the only sessions are optional, the command tag + * must change to TPM2_ST_NO_SESSIONS */ + if (tpm_buf_length(buf) == offset) + head->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS); +} +static inline void tpm_buf_fill_hmac_session(struct tpm_buf *buf, + struct tpm2_auth *auth) +{ +} +static inline int tpm_buf_check_hmac_response(struct tpm_buf *buf, + struct tpm2_auth *auth, + int rc) +{ + return rc; +} +#endif /* CONFIG_TPM_BUS_SECURITY */ + #endif From patchwork Fri Dec 9 16:06:07 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 13069958 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5464BC4332F for ; Fri, 9 Dec 2022 16:10:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229634AbiLIQKE (ORCPT ); Fri, 9 Dec 2022 11:10:04 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54052 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229468AbiLIQKD (ORCPT ); Fri, 9 Dec 2022 11:10:03 -0500 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [IPv6:2607:fcd0:100:8a00::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E8F3D38A1; Fri, 9 Dec 2022 08:10:02 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1670602202; bh=AYt4KHra+GFCWNnVuXL1fFkucm0Cnki8Vo+tlWH9FvQ=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References:From; b=ILTuTcpb6Cstq23HZsP7wWcfP+uAEuZS6JHNIpgpnVxLiRV9gYMGCgKGFBs2wDDg3 KhN+qwh5xvqYl4smdqz73txIWY27vcPKRe8lwVircOVi5t312GlBFomnv3fMLtSiNU WQWzt0tz89fihS4wn0CTf27qOyx8S9qaJmo+Upw8= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id AD4B21281045; Fri, 9 Dec 2022 11:10:02 -0500 (EST) Received: from bedivere.hansenpartnership.com ([127.0.0.1]) by localhost (bedivere.hansenpartnership.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id rdFl-qBSb_CB; Fri, 9 Dec 2022 11:10:02 -0500 (EST) Received: from lingrow.int.hansenpartnership.com (unknown [153.66.160.227]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 0FB3912803C0; Fri, 9 Dec 2022 11:10:01 -0500 (EST) From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Ard Biesheuvel , Jarkko Sakkinen , keyrings@vger.kernel.org Subject: [PATCH 07/11] tpm: add hmac checks to tpm2_pcr_extend() Date: Fri, 9 Dec 2022 11:06:07 -0500 Message-Id: <20221209160611.30207-8-James.Bottomley@HansenPartnership.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20221209160611.30207-1-James.Bottomley@HansenPartnership.com> References: <20221209160611.30207-1-James.Bottomley@HansenPartnership.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: keyrings@vger.kernel.org We use tpm2_pcr_extend() in trusted keys to extend a PCR to prevent a key from being re-loaded until the next reboot. To use this functionality securely, that extend must be protected by a session hmac. Signed-off-by: James Bottomley --- drivers/char/tpm/tpm2-cmd.c | 28 +++++++++++----------------- 1 file changed, 11 insertions(+), 17 deletions(-) diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c index 056dad3dd5c9..001360d5956d 100644 --- a/drivers/char/tpm/tpm2-cmd.c +++ b/drivers/char/tpm/tpm2-cmd.c @@ -216,13 +216,6 @@ int tpm2_pcr_read(struct tpm_chip *chip, u32 pcr_idx, return rc; } -struct tpm2_null_auth_area { - __be32 handle; - __be16 nonce_size; - u8 attributes; - __be16 auth_size; -} __packed; - /** * tpm2_pcr_extend() - extend a PCR value * @@ -236,24 +229,23 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, struct tpm_digest *digests) { struct tpm_buf buf; - struct tpm2_null_auth_area auth_area; + struct tpm2_auth *auth; int rc; int i; - rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND); + rc = tpm2_start_auth_session(chip, &auth); if (rc) return rc; - tpm_buf_append_u32(&buf, pcr_idx); + rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND); + if (rc) { + tpm2_end_auth_session(auth); + return rc; + } - auth_area.handle = cpu_to_be32(TPM2_RS_PW); - auth_area.nonce_size = 0; - auth_area.attributes = 0; - auth_area.auth_size = 0; + tpm_buf_append_name(&buf, auth, pcr_idx, NULL); + tpm_buf_append_hmac_session(&buf, auth, 0, NULL, 0); - tpm_buf_append_u32(&buf, sizeof(struct tpm2_null_auth_area)); - tpm_buf_append(&buf, (const unsigned char *)&auth_area, - sizeof(auth_area)); tpm_buf_append_u32(&buf, chip->nr_allocated_banks); for (i = 0; i < chip->nr_allocated_banks; i++) { @@ -262,7 +254,9 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, chip->allocated_banks[i].digest_size); } + tpm_buf_fill_hmac_session(&buf, auth); rc = tpm_transmit_cmd(chip, &buf, 0, "attempting extend a PCR value"); + rc = tpm_buf_check_hmac_response(&buf, auth, rc); tpm_buf_destroy(&buf); From patchwork Fri Dec 9 16:06:08 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 13069959 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 09FEDC04FDE for ; Fri, 9 Dec 2022 16:10:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229724AbiLIQK2 (ORCPT ); Fri, 9 Dec 2022 11:10:28 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54108 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229683AbiLIQK1 (ORCPT ); Fri, 9 Dec 2022 11:10:27 -0500 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [96.44.175.130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AF9E438A1; Fri, 9 Dec 2022 08:10:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1670602226; bh=jZVB+9oPPrrYNMHjSQd3P3o1B8BU91qtvsviRtwEVFE=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References:From; b=ax9Q8tH0H7YiaiBXb2uh5laVlZQ8AQWfs/6YBHdLHB3alo8vsLQa+nvlrgbbJ3bvk vVMqlr4pMvb7yqli+DOI5HGE53bUoQXN5fBHzprr2yXXO3CelQCaDshuDQUSvBkuX4 T0bG0dCjP6FfmXSOoqiaqLQjZLRS7n9eXVx/8lgU= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 742CC1281045; Fri, 9 Dec 2022 11:10:26 -0500 (EST) Received: from bedivere.hansenpartnership.com ([127.0.0.1]) by localhost (bedivere.hansenpartnership.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id SxKq1fu9EOIE; Fri, 9 Dec 2022 11:10:26 -0500 (EST) Received: from lingrow.int.hansenpartnership.com (unknown [153.66.160.227]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id DE62612803C0; Fri, 9 Dec 2022 11:10:25 -0500 (EST) From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Ard Biesheuvel , Jarkko Sakkinen , keyrings@vger.kernel.org Subject: [PATCH 08/11] tpm: add session encryption protection to tpm2_get_random() Date: Fri, 9 Dec 2022 11:06:08 -0500 Message-Id: <20221209160611.30207-9-James.Bottomley@HansenPartnership.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20221209160611.30207-1-James.Bottomley@HansenPartnership.com> References: <20221209160611.30207-1-James.Bottomley@HansenPartnership.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: keyrings@vger.kernel.org If some entity is snooping the TPM bus, they can see the random numbers we're extracting from the TPM and do prediction attacks against their consumers. Foil this attack by using response encryption to prevent the attacker from seeing the random sequence. Signed-off-by: James Bottomley --- drivers/char/tpm/tpm2-cmd.c | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-) diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c index 001360d5956d..3ac438e8ffbb 100644 --- a/drivers/char/tpm/tpm2-cmd.c +++ b/drivers/char/tpm/tpm2-cmd.c @@ -289,29 +289,40 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max) int total = 0; int retries = 5; u8 *dest_ptr = dest; + struct tpm2_auth *auth; if (!num_bytes || max > TPM_MAX_RNG_DATA) return -EINVAL; - err = tpm_buf_init(&buf, 0, 0); + err = tpm2_start_auth_session(chip, &auth); if (err) return err; + err = tpm_buf_init(&buf, 0, 0); + if (err) { + tpm2_end_auth_session(auth); + return err; + } + do { - tpm_buf_reset(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_RANDOM); + tpm_buf_reset(&buf, TPM2_ST_SESSIONS, TPM2_CC_GET_RANDOM); + tpm_buf_append_hmac_session_opt(&buf, auth, TPM2_SA_ENCRYPT + | TPM2_SA_CONTINUE_SESSION, + NULL, 0); tpm_buf_append_u16(&buf, num_bytes); + tpm_buf_fill_hmac_session(&buf, auth); err = tpm_transmit_cmd(chip, &buf, offsetof(struct tpm2_get_random_out, buffer), "attempting get random"); + err = tpm_buf_check_hmac_response(&buf, auth, err); if (err) { if (err > 0) err = -EIO; goto out; } - out = (struct tpm2_get_random_out *) - &buf.data[TPM_HEADER_SIZE]; + out = (struct tpm2_get_random_out *)tpm_buf_parameters(&buf); recd = min_t(u32, be16_to_cpu(out->size), num_bytes); if (tpm_buf_length(&buf) < TPM_HEADER_SIZE + @@ -328,6 +339,8 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max) } while (retries-- && total < max); tpm_buf_destroy(&buf); + tpm2_end_auth_session(auth); + return total ? total : -EIO; out: tpm_buf_destroy(&buf); From patchwork Fri Dec 9 16:06:09 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 13069960 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 10E87C04FDE for ; Fri, 9 Dec 2022 16:11:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229796AbiLIQLX (ORCPT ); Fri, 9 Dec 2022 11:11:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54588 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229785AbiLIQLV (ORCPT ); Fri, 9 Dec 2022 11:11:21 -0500 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [IPv6:2607:fcd0:100:8a00::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D50EC1CB12; Fri, 9 Dec 2022 08:11:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1670602272; bh=aVqWfBICZBdzpKUNMgQ3GTLMstc9hK4sRbvQPG/t5wU=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References:From; b=E4Y6u+zYAdcQTxjyNE4/HD0O6iNUUaYxwUD2kb2Jms7ZEIIy8Ggxno0NSfjVRwQgv +1CxrL+u80ROhHYsLlaz6J5yXkz3X5/bQ37mqZwPedjG/l3hc/jLQ3B2lwuaZrjpiC GTtYXTMfOpBj8v5BQtxvEN7ZyUdbS4yzC0a1sexw= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id A17BD128611C; Fri, 9 Dec 2022 11:11:12 -0500 (EST) Received: from bedivere.hansenpartnership.com ([127.0.0.1]) by localhost (bedivere.hansenpartnership.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id IxkGnishV_MX; Fri, 9 Dec 2022 11:11:12 -0500 (EST) Received: from lingrow.int.hansenpartnership.com (unknown [153.66.160.227]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 1BA431285E6B; Fri, 9 Dec 2022 11:11:12 -0500 (EST) From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Ard Biesheuvel , Jarkko Sakkinen , keyrings@vger.kernel.org Subject: [PATCH 09/11] KEYS: trusted: Add session encryption protection to the seal/unseal path Date: Fri, 9 Dec 2022 11:06:09 -0500 Message-Id: <20221209160611.30207-10-James.Bottomley@HansenPartnership.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20221209160611.30207-1-James.Bottomley@HansenPartnership.com> References: <20221209160611.30207-1-James.Bottomley@HansenPartnership.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: keyrings@vger.kernel.org If some entity is snooping the TPM bus, the can see the data going in to be sealed and the data coming out as it is unsealed. Add parameter and response encryption to these cases to ensure that no secrets are leaked even if the bus is snooped. As part of doing this conversion it was discovered that policy sessions can't work with HMAC protected authority because of missing pieces (the tpm Nonce). I've added code to work the same way as before, which will result in potential authority exposure (while still adding security for the command and the returned blob), and a fixme to redo the API to get rid of this security hole. Signed-off-by: James Bottomley --- security/keys/trusted-keys/trusted_tpm2.c | 81 ++++++++++++++++------- 1 file changed, 57 insertions(+), 24 deletions(-) diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c index 2b2c8eb258d5..006c419b89c6 100644 --- a/security/keys/trusted-keys/trusted_tpm2.c +++ b/security/keys/trusted-keys/trusted_tpm2.c @@ -230,6 +230,7 @@ int tpm2_seal_trusted(struct tpm_chip *chip, { int blob_len = 0; struct tpm_buf buf; + struct tpm2_auth *auth; u32 hash; u32 flags; int i; @@ -252,18 +253,19 @@ int tpm2_seal_trusted(struct tpm_chip *chip, if (rc) return rc; + rc = tpm2_start_auth_session(chip, &auth); + if (rc) + goto out_put; + rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE); if (rc) { - tpm_put_ops(chip); - return rc; + tpm2_end_auth_session(auth); + goto out_put; } - tpm_buf_append_u32(&buf, options->keyhandle); - tpm2_buf_append_auth(&buf, TPM2_RS_PW, - NULL /* nonce */, 0, - 0 /* session_attributes */, - options->keyauth /* hmac */, - TPM_DIGEST_SIZE); + tpm_buf_append_name(&buf, auth, options->keyhandle, NULL); + tpm_buf_append_hmac_session(&buf, auth, TPM2_SA_DECRYPT, + options->keyauth, TPM_DIGEST_SIZE); /* sensitive */ tpm_buf_append_u16(&buf, 4 + options->blobauth_len + payload->key_len); @@ -308,7 +310,11 @@ int tpm2_seal_trusted(struct tpm_chip *chip, goto out; } + tpm_buf_fill_hmac_session(&buf, auth); rc = tpm_transmit_cmd(chip, &buf, 4, "sealing data"); + if (rc) + goto out; + rc = tpm_buf_check_hmac_response(&buf, auth, rc); if (rc) goto out; @@ -340,6 +346,7 @@ int tpm2_seal_trusted(struct tpm_chip *chip, else payload->blob_len = blob_len; +out_put: tpm_put_ops(chip); return rc; } @@ -363,6 +370,7 @@ static int tpm2_load_cmd(struct tpm_chip *chip, u32 *blob_handle) { struct tpm_buf buf; + struct tpm2_auth *auth; unsigned int private_len; unsigned int public_len; unsigned int blob_len; @@ -409,16 +417,19 @@ static int tpm2_load_cmd(struct tpm_chip *chip, if (blob_len > payload->blob_len) return -E2BIG; - rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_LOAD); + rc = tpm2_start_auth_session(chip, &auth); if (rc) return rc; - tpm_buf_append_u32(&buf, options->keyhandle); - tpm2_buf_append_auth(&buf, TPM2_RS_PW, - NULL /* nonce */, 0, - 0 /* session_attributes */, - options->keyauth /* hmac */, - TPM_DIGEST_SIZE); + rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_LOAD); + if (rc) { + tpm2_end_auth_session(auth); + return rc; + } + + tpm_buf_append_name(&buf, auth, options->keyhandle, NULL); + tpm_buf_append_hmac_session(&buf, auth, 0, options->keyauth, + TPM_DIGEST_SIZE); tpm_buf_append(&buf, blob, blob_len); @@ -427,7 +438,9 @@ static int tpm2_load_cmd(struct tpm_chip *chip, goto out; } + tpm_buf_fill_hmac_session(&buf, auth); rc = tpm_transmit_cmd(chip, &buf, 4, "loading blob"); + rc = tpm_buf_check_hmac_response(&buf, auth, rc); if (!rc) *blob_handle = be32_to_cpup( (__be32 *) &buf.data[TPM_HEADER_SIZE]); @@ -461,24 +474,44 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip, u32 blob_handle) { struct tpm_buf buf; + struct tpm2_auth *auth; u16 data_len; u8 *data; int rc; - rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL); + rc = tpm2_start_auth_session(chip, &auth); if (rc) return rc; - tpm_buf_append_u32(&buf, blob_handle); - tpm2_buf_append_auth(&buf, - options->policyhandle ? - options->policyhandle : TPM2_RS_PW, - NULL /* nonce */, 0, - TPM2_SA_CONTINUE_SESSION, - options->blobauth /* hmac */, - options->blobauth_len); + rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL); + if (rc) { + tpm2_end_auth_session(auth); + return rc; + } + + tpm_buf_append_name(&buf, auth, blob_handle, NULL); + + if (!options->policyhandle) { + tpm_buf_append_hmac_session(&buf, auth, TPM2_SA_ENCRYPT, + options->blobauth, TPM_DIGEST_SIZE); + } else { + /* + * FIXME: if we generated the policyhandle, we know the nonce + * and therefore could use it for session encryption, but we + * can't for the external policy handle case, so we treat both + * the same here. + */ + tpm2_buf_append_auth(&buf, options->policyhandle, + NULL /* nonce */, 0, 0, + options->blobauth /* hmac */, + TPM_DIGEST_SIZE); + tpm_buf_append_hmac_session_opt(&buf, auth, TPM2_SA_ENCRYPT, + NULL, 0); + } + tpm_buf_fill_hmac_session(&buf, auth); rc = tpm_transmit_cmd(chip, &buf, 6, "unsealing"); + rc = tpm_buf_check_hmac_response(&buf, auth, rc); if (rc > 0) rc = -EPERM; From patchwork Fri Dec 9 16:06:10 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 13069961 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9CE5EC4167B for ; Fri, 9 Dec 2022 16:11:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229605AbiLIQLu (ORCPT ); Fri, 9 Dec 2022 11:11:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54758 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229733AbiLIQLh (ORCPT ); Fri, 9 Dec 2022 11:11:37 -0500 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [IPv6:2607:fcd0:100:8a00::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4867C8D18F; Fri, 9 Dec 2022 08:11:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1670602297; bh=zxOEdwuaalwNHiGC2e67a2mJ2T7BWRsyBWZcOivzm1I=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References:From; b=mgQud3TvrGte2OcffE2jW+OjJegNvlS76LZL06TAkY2/54RNVg2ZikHp2VuV0oWQf VsN6jbF56dG8D6VBuUZO1Diq7Zi/N2Mikp3gIFkSapDe0P/63dDH5RyZTXDDaw6vCT Hpk85x8PolnGvlyWUI5qlFMde/VgTTxduOd8LeWQ= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 153371285ED4; Fri, 9 Dec 2022 11:11:37 -0500 (EST) Received: from bedivere.hansenpartnership.com ([127.0.0.1]) by localhost (bedivere.hansenpartnership.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Sa9bGXVMIw14; Fri, 9 Dec 2022 11:11:37 -0500 (EST) Received: from lingrow.int.hansenpartnership.com (unknown [153.66.160.227]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 76A5C1285E6B; Fri, 9 Dec 2022 11:11:36 -0500 (EST) From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Ard Biesheuvel , Jarkko Sakkinen , keyrings@vger.kernel.org Subject: [PATCH 10/11] tpm: add the null key name as a sysfs export Date: Fri, 9 Dec 2022 11:06:10 -0500 Message-Id: <20221209160611.30207-11-James.Bottomley@HansenPartnership.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20221209160611.30207-1-James.Bottomley@HansenPartnership.com> References: <20221209160611.30207-1-James.Bottomley@HansenPartnership.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: keyrings@vger.kernel.org This is the last component of encrypted tpm2 session handling that allows us to verify from userspace that the key derived from the NULL seed genuinely belongs to the TPM and has not been spoofed. The procedure for doing this involves creating an attestation identity key (which requires verification of the TPM EK certificate) and then using that AIK to sign a certification of the Elliptic Curve key over the NULL seed. Userspace must create this EC Key using the parameters prescribed in TCG TPM v2.0 Provisioning Guidance for the SRK ECC; if this is done correctly the names will match and the TPM can then run a TPM2_Certify operation on this derived primary key using the newly created AIK. Signed-off-by: James Bottomley --- drivers/char/tpm/tpm-sysfs.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c index 54c71473aa29..27a16addab93 100644 --- a/drivers/char/tpm/tpm-sysfs.c +++ b/drivers/char/tpm/tpm-sysfs.c @@ -309,6 +309,19 @@ static ssize_t tpm_version_major_show(struct device *dev, } static DEVICE_ATTR_RO(tpm_version_major); +static ssize_t null_name_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct tpm_chip *chip = to_tpm_chip(dev); + int size = TPM2_NAME_SIZE; + + bin2hex(buf, chip->tpmkeyname, size); + size *= 2; + buf[size++] = '\n'; + return size; +} +static DEVICE_ATTR_RO(null_name); + static struct attribute *tpm1_dev_attrs[] = { &dev_attr_pubek.attr, &dev_attr_pcrs.attr, @@ -326,6 +339,7 @@ static struct attribute *tpm1_dev_attrs[] = { static struct attribute *tpm2_dev_attrs[] = { &dev_attr_tpm_version_major.attr, + &dev_attr_null_name.attr, NULL }; From patchwork Fri Dec 9 16:06:11 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 13069962 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3C79AC4332F for ; Fri, 9 Dec 2022 16:12:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229478AbiLIQMt (ORCPT ); Fri, 9 Dec 2022 11:12:49 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55134 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229498AbiLIQMU (ORCPT ); Fri, 9 Dec 2022 11:12:20 -0500 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [96.44.175.130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4C63B60F7; Fri, 9 Dec 2022 08:12:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1670602339; bh=Gh5uVY2QA+QJh/nQ/7xnlhYfLYfvDs3iyzaKPASnajg=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References:From; b=dTSXMq8dRDqilVaNcyZvn+Bch/TwN4Wsmee3o+M3HNgr73TjzL61rEqpqPzSbiAr4 MhZTxdIk2zcKuwbowqRSSQug6IJKaFQqtNxWjiP5nTA4UJ5MQCkIVKhZSSV1Bml+Sh XwPdecnmMgF++vhgtTO00Pylm30qSXrDECheLUDs= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 002E51285ED4; Fri, 9 Dec 2022 11:12:19 -0500 (EST) Received: from bedivere.hansenpartnership.com ([127.0.0.1]) by localhost (bedivere.hansenpartnership.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id izdfG19Q6lEs; Fri, 9 Dec 2022 11:12:18 -0500 (EST) Received: from lingrow.int.hansenpartnership.com (unknown [153.66.160.227]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 6E64C1285E6B; Fri, 9 Dec 2022 11:12:18 -0500 (EST) From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Ard Biesheuvel , Jarkko Sakkinen , keyrings@vger.kernel.org Subject: [PATCH 11/11] Documentation: add tpm-security.rst Date: Fri, 9 Dec 2022 11:06:11 -0500 Message-Id: <20221209160611.30207-12-James.Bottomley@HansenPartnership.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20221209160611.30207-1-James.Bottomley@HansenPartnership.com> References: <20221209160611.30207-1-James.Bottomley@HansenPartnership.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: keyrings@vger.kernel.org Document how the new encrypted secure interface for TPM2 works and how security can be assured after boot by certifying the NULL seed. Signed-off-by: James Bottomley --- Documentation/security/tpm/tpm-security.rst | 214 ++++++++++++++++++++ 1 file changed, 214 insertions(+) create mode 100644 Documentation/security/tpm/tpm-security.rst diff --git a/Documentation/security/tpm/tpm-security.rst b/Documentation/security/tpm/tpm-security.rst new file mode 100644 index 000000000000..922b80db3d48 --- /dev/null +++ b/Documentation/security/tpm/tpm-security.rst @@ -0,0 +1,214 @@ +TPM Security +============ + +The object of this document is to describe how we make the kernel's +use of the TPM reasonably robust in the face of external snooping and +packet alteration attacks (called passive and active interposer attack +in the literature). The current security document is for TPM 2.0. + +Introduction +------------ + +The TPM is usually a discrete chip attached to a PC via some type of +low bandwidth bus. There are exceptions to this such as the Intel +PTT, which is a software TPM running inside a software environment +close to the CPU, which are subject to different attacks, but right at +the moment, most hardened security environments require a discrete +hardware TPM, which is the use case discussed here. + +Snooping and Alteration Attacks against the bus +----------------------------------------------- + +The current state of the art for snooping the `TPM Genie`_ hardware +interposer which is a simple external device that can be installed in +a couple of seconds on any system or laptop. Recently attacks were +successfully demonstrated against the `Windows Bitlocker TPM`_ system. +Most recently the same `attack against TPM based Linux disk +encryption`_ schemes. The next phase of research seems to be hacking +existing devices on the bus to act as interposers, so the fact that +the attacker requires physical access for a few seconds might +evaporate. However, the goal of this document is to protect TPM +secrets and integrity as far as we are able in this environment and to +try to insure that if we can't prevent the attack then at least we can +detect it. + +Unfortunately, most of the TPM functionality, including the hardware +reset capability can be controlled by an attacker who has access to +the bus, so we'll discuss some of the disruption possibilities below. + +Measurement (PCR) Integrity +--------------------------- + +Since the attacker can send their own commands to the TPM, they can +send arbitrary PCR extends and thus disrupt the measurement system, +which would be an annoying denial of service attack. However, there +are two, more serious, classes of attack aimed at entities sealed to +trust measurements. + +1. The attacker could intercept all PCR extends coming from the system + and completely substitute their own values, producing a replay of + an untampered state that would cause PCR measurements to attest to + a trusted state and release secrets + +2. At some point in time the attacker could reset the TPM, clearing + the PCRs and then send down their own measurements which would + effectively overwrite the boot time measurements the TPM has + already done. + +The first can be thwarted by always doing HMAC protection of the PCR +extend and read command meaning measurement values cannot be +substituted without producing a detectable HMAC failure in the +response. However, the second can only really be detected by relying +on some sort of mechanism for protection which would change over TPM +reset. + +Secrets Guarding +---------------- + +Certain information passing in and out of the TPM, such as key sealing +and private key import and random number generation, is vulnerable to +interception which HMAC protection alone cannot protect against, so +for these types of command we must also employ request and response +encryption to prevent the loss of secret information. + +Establishing Initial Trust with the TPM +--------------------------------------- + +In order to provide security from the beginning, an initial shared or +asymmetric secret must be established which must also be unknown to +the attacker. The most obvious avenues for this are the endorsement +and storage seeds, which can be used to derive asymmetric keys. +However, using these keys is difficult because the only way to pass +them into the kernel would be on the command line, which requires +extensive support in the boot system, and there's no guarantee that +either hierarchy would not have some type of authorization. + +The mechanism chosen for the Linux Kernel is to derive the primary +elliptic curve key from the null seed using the standard storage seed +parameters. The null seed has two advantages: firstly the hierarchy +physically cannot have an authorization, so we are always able to use +it and secondly, the null seed changes across TPM resets, meaning if +we establish trust on the null seed at start of day, all sessions +salted with the derived key will fail if the TPM is reset and the seed +changes. + +Obviously using the null seed without any other prior shared secrets, +we have to create and read the initial public key which could, of +course, be intercepted and substituted by the bus interposer. +However, the TPM has a key certification mechanism (using the EK +endorsement certificate, creating an attestation identity key and +certifying the null seed primary with that key) which is too complex +to run within the kernel, so we keep a copy of the null primary key +name, which is what is exported via sysfs so user-space can run the +full certification when it boots. The definitive guarantee here is +that if the null primary key certifies correctly, you know all your +TPM transactions since start of day were secure and if it doesn't, you +know there's an interposer on your system (and that any secret used +during boot may have been leaked). + +Stacking Trust +-------------- + +In the current null primary scenario, the TPM must be completely +cleared before handing it on to the next consumer. However the kernel +hands to user-space the name of the derived null seed key which can +then be verified by certification in user-space. Therefore, this chain +of name handoff can be used between the various boot components as +well (via an unspecified mechanism). For instance, grub could use the +null seed scheme for security and hand the name off to the kernel in +the boot area. The kernel could make its own derivation of the key +and the name and know definitively that if they differ from the handed +off version that tampering has occurred. Thus it becomes possible to +chain arbitrary boot components together (UEFI to grub to kernel) via +the name handoff provided each successive component knows how to +collect the name and verifies it against its derived key. + +Session Properties +------------------ + +All TPM commands the kernel uses allow sessions. HMAC sessions may be +used to check the integrity of requests and responses and decrypt and +encrypt flags may be used to shield parameters and responses. The +HMAC and encryption keys are usually derived from the shared +authorization secret, but for a lot of kernel operations that is well +known (and usually empty). Thus, every HMAC session used by the +kernel must be created using the null primary key as the salt key +which thus provides a cryptographic input into the session key +derivation. Thus, the kernel creates the null primary key once (as a +volatile TPM handle) and keeps it around in a saved context stored in +tpm_chip for every in-kernel use of the TPM. Currently, because of a +lack of de-gapping in the in-kernel resource manager, the session must +be created and destroyed for each operation, but, in future, a single +session may also be reused for the in-kernel HMAC, encryption and +decryption sessions. + +Protection Types +---------------- + +For every in-kernel operation we use null primary salted HMAC to +protect the integrity. Additionally, we use parameter encryption to +protect key sealing and parameter decryption to protect key unsealing +and random number generation. + +Null Primary Key Certification in Userspace +=========================================== + +Every TPM comes shipped with a couple of X.509 certificates for the +primary endorsement key. This document assumes that the Elliptic +Curve version of the certificate exists at 01C00002, but will work +equally well with the RSA certificate (at 01C00001). + +The first step in the certification is primary creation using the +template from the `TCG EK Credential Profile`_ which allows comparison +of the generated primary key against the one in the certificate (the +public key must match). Note that generation of the EK primary +requires the EK hierarchy password, but a pre-generated version of the +EC primary should exist at 81010002 and a TPM2_ReadPublic() may be +performed on this without needing the key authority. Next, the +certificate itself must be verified to chain back to the manufacturer +root (which should be published on the manufacturer website). Once +this is done, an attestation key (AK) is generated within the TPM and +it's name and the EK public key can be used to encrypt a secret using +TPM2_MakeCredential. The TPM then runs TPM2_ActivateCredential which +will only recover the secret if the binding between the TPM, the EK +and the AK is true. the generated AK may now be used to run a +certification of the null primary key whose name the kernel has +exported. Since TPM2_MakeCredential/ActivateCredential are somewhat +complicated, a more simplified process involving an externally +generated private key is described below. + +This process is a simplified abbreviation of the usual privacy CA +based attestation process. The assumption here is that the +attestation is done by the TPM owner who thus has access to only the +owner hierarchy. The owner creates an external public/private key +pair (assume elliptic curve in this case) and wraps the private key +for import using an inner wrapping process and parented to the EC +derived storage primary. The TPM2_Import() is done using a parameter +decryption HMAC session salted to the EK primary (which also does not +require the EK key authority) meaning that the inner wrapping key is +the encrypted parameter and thus the TPM will not be able to perform +the import unless is possesses the certified EK so if the command +succeeds and the HMAC verifies on return we know we have a loadable +copy of the private key only for the certified TPM. This key is now +loaded into the TPM and the Storage primary flushed (to free up space +for the null key generation). + +The null EC primary is now generated using the Storage profile +outlined in the `TCG TPM v2.0 Provisioning Guidance`_; the name of +this key (the hash of the public area) is computed and compared to the +null seed name presented by the kernel in +/sys/class/tpm/tpm0/null_name. If the names do not match, the TPM is +compromised. If the names match, the user performs a TPM2_Certify() +using the null primary as the object handle and the loaded private key +as the sign handle and providing randomized qualifying data. The +signature of the returned certifyInfo is verified against the public +part of the loaded private key and the qualifying data checked to +prevent replay. If all of these tests pass, the user is now assured +that TPM integrity and privacy was preserved across the entire boot +sequence of this kernel. + +.. _TPM Genie: https://www.nccgroup.trust/globalassets/about-us/us/documents/tpm-genie.pdf +.. _Windows Bitlocker TPM: https://dolosgroup.io/blog/2021/7/9/from-stolen-laptop-to-inside-the-company-network +.. _attack against TPM based Linux disk encryption: https://www.secura.com/blog/tpm-sniffing-attacks-against-non-bitlocker-targets +.. _TCG EK Credential Profile: https://trustedcomputinggroup.org/resource/tcg-ek-credential-profile-for-tpm-family-2-0/ +.. _TCG TPM v2.0 Provisioning Guidance: https://trustedcomputinggroup.org/resource/tcg-tpm-v2-0-provisioning-guidance/