From patchwork Thu Feb 16 20:13:59 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 13143709 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 3C103C636CC for ; Thu, 16 Feb 2023 20:15:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229784AbjBPUPQ (ORCPT ); Thu, 16 Feb 2023 15:15:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36998 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229561AbjBPUPP (ORCPT ); Thu, 16 Feb 2023 15:15:15 -0500 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [96.44.175.130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0BAB04C6D7; Thu, 16 Feb 2023 12:15:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1676578514; bh=A+1Y4qtwYNGm0gXQjLE/ci9ci8qKKuU2t07hz37bvEk=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References:From; b=TsoqPSRX59yRWrKUfotEmtPnIyWLcG+C4h4Er+Kj9BfBTx3StGAzJruUaQXHT9AFr VXm8ZLm7sT2/PsDwXcp8M2Z1O2QHy9TiJqfoT5Otsm5zEeM6DBYyNPIhp4PLBoa+ej POB6GSJVS57CELZE4jV+57CAsCRQHZG5+USRcbIE= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id B2F8C1286E47; Thu, 16 Feb 2023 15:15:14 -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 oi71gDhzLgIT; Thu, 16 Feb 2023 15:15:14 -0500 (EST) Received: from lingrow.int.hansenpartnership.com (unknown [153.66.160.227]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 2ADF41286F45; Thu, 16 Feb 2023 15:15:14 -0500 (EST) From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Jarkko Sakkinen , keyrings@vger.kernel.org, Ard Biesheuvel Subject: [PATCH 01/12] crypto: lib - implement library version of AES in CFB mode Date: Thu, 16 Feb 2023 15:13:59 -0500 Message-Id: <20230216201410.15010-2-James.Bottomley@HansenPartnership.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20230216201410.15010-1-James.Bottomley@HansenPartnership.com> References: <20230216201410.15010-1-James.Bottomley@HansenPartnership.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: keyrings@vger.kernel.org From: Ard Biesheuvel Implement AES in CFB mode using the existing, mostly constant-time generic AES library implementation. Signed-off-by: Ard Biesheuvel Signed-off-by: James Bottomley Reviewed-by: Jarkko Sakkinen --- include/crypto/aes.h | 5 +++ lib/crypto/Kconfig | 5 +++ lib/crypto/Makefile | 3 ++ lib/crypto/aescfb.c | 75 ++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 88 insertions(+) create mode 100644 lib/crypto/aescfb.c diff --git a/include/crypto/aes.h b/include/crypto/aes.h index 2090729701ab..7b9e1df1ccb0 100644 --- a/include/crypto/aes.h +++ b/include/crypto/aes.h @@ -87,4 +87,9 @@ void aes_decrypt(const struct crypto_aes_ctx *ctx, u8 *out, const u8 *in); extern const u8 crypto_aes_sbox[]; extern const u8 crypto_aes_inv_sbox[]; +void aescfb_encrypt(const struct crypto_aes_ctx *ctx, u8 *dst, const u8 *src, + int len, const u8 *iv); +void aescfb_decrypt(const struct crypto_aes_ctx *ctx, u8 *dst, const u8 *src, + int len, const u8 *iv); + #endif diff --git a/lib/crypto/Kconfig b/lib/crypto/Kconfig index 45436bfc6dff..b01253cac70a 100644 --- a/lib/crypto/Kconfig +++ b/lib/crypto/Kconfig @@ -8,6 +8,11 @@ config CRYPTO_LIB_UTILS config CRYPTO_LIB_AES tristate +config CRYPTO_LIB_AESCFB + tristate + select CRYPTO_LIB_AES + select CRYPTO_LIB_UTILS + config CRYPTO_LIB_AESGCM tristate select CRYPTO_LIB_AES diff --git a/lib/crypto/Makefile b/lib/crypto/Makefile index 6ec2d4543d9c..33213a01aab1 100644 --- a/lib/crypto/Makefile +++ b/lib/crypto/Makefile @@ -10,6 +10,9 @@ obj-$(CONFIG_CRYPTO_LIB_CHACHA_GENERIC) += libchacha.o obj-$(CONFIG_CRYPTO_LIB_AES) += libaes.o libaes-y := aes.o +obj-$(CONFIG_CRYPTO_LIB_AESCFB) += libaescfb.o +libaescfb-y := aescfb.o + obj-$(CONFIG_CRYPTO_LIB_AESGCM) += libaesgcm.o libaesgcm-y := aesgcm.o diff --git a/lib/crypto/aescfb.c b/lib/crypto/aescfb.c new file mode 100644 index 000000000000..e9de1c6d874a --- /dev/null +++ b/lib/crypto/aescfb.c @@ -0,0 +1,75 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Minimal library implementation of AES in CFB mode + * + * Copyright 2023 Google LLC + */ + +#include + +#include +#include + +#include + +static void aescfb_encrypt_block(const struct crypto_aes_ctx *ctx, void *dst, + const void *src) +{ + unsigned long flags; + + /* + * In AES-CFB, the AES encryption operates on known 'plaintext' (the IV + * and ciphertext), making it susceptible to timing attacks on the + * encryption key. The AES library already mitigates this risk to some + * extent by pulling the entire S-box into the caches before doing any + * substitutions, but this strategy is more effective when running with + * interrupts disabled. + */ + local_irq_save(flags); + aes_encrypt(ctx, dst, src); + local_irq_restore(flags); +} + +void aescfb_encrypt(const struct crypto_aes_ctx *ctx, u8 *dst, const u8 *src, + int len, const u8 *iv) +{ + while (len > 0) { + u8 ks[AES_BLOCK_SIZE]; + + aescfb_encrypt_block(ctx, ks, iv); + crypto_xor_cpy(dst, src, ks, min(len, AES_BLOCK_SIZE)); + iv = dst; + + dst += AES_BLOCK_SIZE; + src += AES_BLOCK_SIZE; + len -= AES_BLOCK_SIZE; + } +} + +void aescfb_decrypt(const struct crypto_aes_ctx *ctx, u8 *dst, const u8 *src, + int len, const u8 *iv) +{ + u8 ks[2][AES_BLOCK_SIZE]; + + aescfb_encrypt_block(ctx, ks[0], iv); + + for (int i = 0; len > 0; i ^= 1) { + if (len > AES_BLOCK_SIZE) + /* + * Generate the keystream for the next block before + * performing the XOR, as that may update in place and + * overwrite the ciphertext. + */ + aescfb_encrypt_block(ctx, ks[!i], src); + + crypto_xor_cpy(dst, src, ks[i], min(len, AES_BLOCK_SIZE)); + + dst += AES_BLOCK_SIZE; + src += AES_BLOCK_SIZE; + len -= AES_BLOCK_SIZE; + } +} + +MODULE_DESCRIPTION("Generic AES-CFB library"); +MODULE_AUTHOR("Ard Biesheuvel "); +MODULE_LICENSE("GPL"); From patchwork Thu Feb 16 20:14:00 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 13143710 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 EEAF0C636CC for ; Thu, 16 Feb 2023 20:15:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229863AbjBPUPo (ORCPT ); Thu, 16 Feb 2023 15:15:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37034 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229520AbjBPUPn (ORCPT ); Thu, 16 Feb 2023 15:15:43 -0500 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [IPv6:2607:fcd0:100:8a00::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8B8AC4C6D7; Thu, 16 Feb 2023 12:15:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1676578542; bh=jFyQt7cPvUlMBJu/IPwilokw4IssDw03IOIw5pH9nsA=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References:From; b=suJMw1ZlpxtrIOwWX8oJi1TVqDfXj9ic8/ntcsDC2Hz4nQ9OZLDR9cxky+SEbVQS6 ZTUtW0xMc29lAN1X2p/fiTXiRgyou8BZkqXNYY7y515gnQH4oc6G5wQQkf9XXza1Mi PPgohryvbYy+F5JJKtsKxDtnJrGM8Ts3dUQgwrgo= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 5E0281286F45; Thu, 16 Feb 2023 15:15:42 -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 ip_IubZ78uSf; Thu, 16 Feb 2023 15:15:42 -0500 (EST) Received: from lingrow.int.hansenpartnership.com (unknown [153.66.160.227]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id C1FD31286E47; Thu, 16 Feb 2023 15:15:41 -0500 (EST) From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Jarkko Sakkinen , keyrings@vger.kernel.org, Ard Biesheuvel Subject: [PATCH 02/12] tpm: move buffer handling from static inlines to real functions Date: Thu, 16 Feb 2023 15:14:00 -0500 Message-Id: <20230216201410.15010-3-James.Bottomley@HansenPartnership.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20230216201410.15010-1-James.Bottomley@HansenPartnership.com> References: <20230216201410.15010-1-James.Bottomley@HansenPartnership.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: keyrings@vger.kernel.org separate out the tpm_buf_... handling functions from static inlines in tpm.h and move them to their own tpm-buf.c file. This is a precursor to adding new functions for other TPM type handling because the amount of code will grow from the current 70 lines in tpm.h to about 200 lines when the additions are done. 200 lines of inline functions is a bit too much to keep in a header file. Signed-off-by: James Bottomley --- v3: make tpm_buf_tag static --- drivers/char/tpm/Makefile | 1 + drivers/char/tpm/tpm-buf.c | 95 ++++++++++++++++++++++++++++++++++++++ include/linux/tpm.h | 86 ++++------------------------------ 3 files changed, 105 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..ca59b92e0f95 --- /dev/null +++ b/drivers/char/tpm/tpm-buf.c @@ -0,0 +1,95 @@ +// 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); + +static u16 tpm_buf_tag(struct tpm_buf *buf) +{ + struct tpm_header *head = (struct tpm_header *)buf->data; + + return be16_to_cpu(head->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 Thu Feb 16 20:14:01 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 13143711 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 0361FC636CC for ; Thu, 16 Feb 2023 20:16:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229886AbjBPUQB (ORCPT ); Thu, 16 Feb 2023 15:16:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37080 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229520AbjBPUQA (ORCPT ); Thu, 16 Feb 2023 15:16:00 -0500 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [96.44.175.130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B5FFB4CC82; Thu, 16 Feb 2023 12:15:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1676578559; bh=0PK11a71qj0IYpX4859Rl/vlnRDszC8pil/vfS6X6ek=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References:From; b=G5+yeQcJ2PdjzgKbkwjPSz0iuOBJbIJ0qtpoSMQyi1Tb3kn6D+YpRBMxj+btTgRLf XDyzgNOCnduPB81BshhC2+HoMUAOCa1998bB4umz9qLBYnWA99Yupa74Poc+rvzTQs Lfu2dgHB0yQl1FOx4wuzFlwAl+vMyZVhz59owuYk= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 684C31286F45; Thu, 16 Feb 2023 15:15:59 -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 oMt3q6EzFsau; Thu, 16 Feb 2023 15:15:59 -0500 (EST) Received: from lingrow.int.hansenpartnership.com (unknown [153.66.160.227]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id D92421286E47; Thu, 16 Feb 2023 15:15:58 -0500 (EST) From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Jarkko Sakkinen , keyrings@vger.kernel.org, Ard Biesheuvel Subject: [PATCH 03/12] tpm: add buffer handling for TPM2B types Date: Thu, 16 Feb 2023 15:14:01 -0500 Message-Id: <20230216201410.15010-4-James.Bottomley@HansenPartnership.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20230216201410.15010-1-James.Bottomley@HansenPartnership.com> References: <20230216201410.15010-1-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 ca59b92e0f95..292c6f14f72c 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); @@ -55,7 +97,7 @@ 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) @@ -93,3 +135,22 @@ 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 Thu Feb 16 20:14:02 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 13143712 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 EF2F2C61DA4 for ; Thu, 16 Feb 2023 20:16:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229888AbjBPUQR (ORCPT ); Thu, 16 Feb 2023 15:16:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37146 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229520AbjBPUQQ (ORCPT ); Thu, 16 Feb 2023 15:16:16 -0500 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [IPv6:2607:fcd0:100:8a00::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 959CE4C6D7; Thu, 16 Feb 2023 12:16:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1676578575; bh=SYvWaFlWqScJVSJQhSfehs2czXvOZYIZhECUkS1mEAI=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References:From; b=YxtAGVIoNu1YUiish7DZd3Gge+JHJFZl5qfUEAgHiAcXHqdsqGltdLzvbfe0/rxSF Fz1ls+sQnhS+NPRt4YAvATCnwvhVQEL74aC1RUnqZU6oj6bhQqZM5F8k/NrTr6GDom PvhQSDG1coJhln9SUEs0lTxZlGhZd6jCxUnrHC7U= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 62AB11286F45; Thu, 16 Feb 2023 15:16:15 -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 jZRZ_n6Wrqoq; Thu, 16 Feb 2023 15:16:15 -0500 (EST) Received: from lingrow.int.hansenpartnership.com (unknown [153.66.160.227]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id AF8B21286E47; Thu, 16 Feb 2023 15:16:14 -0500 (EST) From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Jarkko Sakkinen , keyrings@vger.kernel.org, Ard Biesheuvel Subject: [PATCH 04/12] tpm: add cursor based buffer functions for response parsing Date: Thu, 16 Feb 2023 15:14:02 -0500 Message-Id: <20230216201410.15010-5-James.Bottomley@HansenPartnership.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20230216201410.15010-1-James.Bottomley@HansenPartnership.com> References: <20230216201410.15010-1-James.Bottomley@HansenPartnership.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: keyrings@vger.kernel.org Once we have encryption and authentication, marshalling and unmarshalling sessions becomes hugely complex. Add cursor based functions which update the current pointer to make response parsing easier. 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 292c6f14f72c..b76158f9bcd0 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); @@ -154,3 +156,30 @@ 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 Thu Feb 16 20:14:03 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 13143713 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 CBF66C636CC for ; Thu, 16 Feb 2023 20:16:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229895AbjBPUQy (ORCPT ); Thu, 16 Feb 2023 15:16:54 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37236 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229520AbjBPUQx (ORCPT ); Thu, 16 Feb 2023 15:16:53 -0500 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [IPv6:2607:fcd0:100:8a00::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DBE554C6D7; Thu, 16 Feb 2023 12:16:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1676578612; bh=C0MGC7VsBgPg+6qRsvVHZVK5AN1MRr55IgymOILL5+Q=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References:From; b=s0+rxjSe0at5zBxQevZPRXNeImNm0rUv+KFLA/KHRx2B8b6/LtJJqxAKcQmywQrUb Liix325QLbPU+MerVFkdeHTc8+lq5g9f1w3ECwQu4KwmCQxmMCpOqo+SPWIe2AC5WJ 5IzwEHUovwwalBdRon0dwDkoJ10XUwqhXdN/vjBI= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id A8EA91286F45; Thu, 16 Feb 2023 15:16:52 -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 fDXLGMWlVVjB; Thu, 16 Feb 2023 15:16:52 -0500 (EST) Received: from lingrow.int.hansenpartnership.com (unknown [153.66.160.227]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 2F0311286E47; Thu, 16 Feb 2023 15:16:52 -0500 (EST) From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Jarkko Sakkinen , keyrings@vger.kernel.org, Ard Biesheuvel Subject: [PATCH 05/12] tpm: add buffer function to point to returned parameters Date: Thu, 16 Feb 2023 15:14:03 -0500 Message-Id: <20230216201410.15010-6-James.Bottomley@HansenPartnership.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20230216201410.15010-1-James.Bottomley@HansenPartnership.com> References: <20230216201410.15010-1-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 b76158f9bcd0..2518b675e866 100644 --- a/drivers/char/tpm/tpm-buf.c +++ b/drivers/char/tpm/tpm-buf.c @@ -183,3 +183,13 @@ 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 Thu Feb 16 20:14:04 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 13143714 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 2C4F0C636CC for ; Thu, 16 Feb 2023 20:17:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229525AbjBPURa (ORCPT ); Thu, 16 Feb 2023 15:17:30 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37292 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229475AbjBPUR3 (ORCPT ); Thu, 16 Feb 2023 15:17:29 -0500 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [96.44.175.130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 028D84C6D7; Thu, 16 Feb 2023 12:17:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1676578648; bh=SACuZ9qQZKFkIBEj5nHX9mpXGYN9nESZN0qGMbrT3zI=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References:From; b=Oxbbgt7sM/1OUrdo7WhJZuQuXlZ8Q02A091At3s4khEpPIgvL2w4qs4Gb6J5yk46D dczW7QbhkcETjnmPm5JS/AebUnw7CKnO1grpPk5LmplaV4BjMNqvMxyGPNRbWes/nY qfh8HkPRm+Ysv9v/rqmrrawU6o2YXgsmSNzYgMSc= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id B55661286F45; Thu, 16 Feb 2023 15:17:28 -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 s0bZ0y5hLMXm; Thu, 16 Feb 2023 15:17:28 -0500 (EST) Received: from lingrow.int.hansenpartnership.com (unknown [153.66.160.227]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 31ABD1286E47; Thu, 16 Feb 2023 15:17:28 -0500 (EST) From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Jarkko Sakkinen , keyrings@vger.kernel.org, Ard Biesheuvel Subject: [PATCH 06/12] tpm: export the context save and load commands Date: Thu, 16 Feb 2023 15:14:04 -0500 Message-Id: <20230216201410.15010-7-James.Bottomley@HansenPartnership.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20230216201410.15010-1-James.Bottomley@HansenPartnership.com> References: <20230216201410.15010-1-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 Thu Feb 16 20:14:05 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 13143715 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 70E41C61DA4 for ; Thu, 16 Feb 2023 20:18:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229650AbjBPUSO (ORCPT ); Thu, 16 Feb 2023 15:18:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38286 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229561AbjBPUSN (ORCPT ); Thu, 16 Feb 2023 15:18:13 -0500 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [96.44.175.130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7FAD23773C; Thu, 16 Feb 2023 12:18:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1676578688; bh=kWZA1ibWICKoRSUvAotPWzcUBVHkFvUBtaEpLONugck=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References:From; b=MnYlClUJYhzh1Arz4YIKwakonUf03Z65bx3v3Xxf/HEjo/b8BCEVa22JeoEq89CsP J7xZnmECxUey9we7JQUK+285SanPmEetRBg3vFO+wrrIW7G1vew5yLxkeR+rYXh0bw 8W1MggbJwIoOUaQcHNqNYIsUrSmuEQvrmM/afTZI= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 474201286F45; Thu, 16 Feb 2023 15:18:08 -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 MsHDhYryZgRk; Thu, 16 Feb 2023 15:18:08 -0500 (EST) Received: from lingrow.int.hansenpartnership.com (unknown [153.66.160.227]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 8ADAD1286E47; Thu, 16 Feb 2023 15:18:07 -0500 (EST) From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Jarkko Sakkinen , keyrings@vger.kernel.org, Ard Biesheuvel Subject: [PATCH 07/12] tpm: Add full HMAC and encrypt/decrypt session handling code Date: Thu, 16 Feb 2023 15:14:05 -0500 Message-Id: <20230216201410.15010-8-James.Bottomley@HansenPartnership.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20230216201410.15010-1-James.Bottomley@HansenPartnership.com> References: <20230216201410.15010-1-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 --- v2: fix memory leaks from smatch; adjust for name hash size v3: make tpm2_make_null_primary static v4: use crypto library functions --- drivers/char/tpm/Kconfig | 13 + drivers/char/tpm/Makefile | 1 + drivers/char/tpm/tpm-buf.c | 1 + drivers/char/tpm/tpm-chip.c | 3 + drivers/char/tpm/tpm.h | 10 + drivers/char/tpm/tpm2-cmd.c | 5 + drivers/char/tpm/tpm2-sessions.c | 1160 ++++++++++++++++++++++++++++++ include/linux/tpm.h | 165 +++++ 8 files changed, 1358 insertions(+) create mode 100644 drivers/char/tpm/tpm2-sessions.c diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig index 927088b2c3d3..8af3afc48511 100644 --- a/drivers/char/tpm/Kconfig +++ b/drivers/char/tpm/Kconfig @@ -27,6 +27,19 @@ menuconfig TCG_TPM if TCG_TPM +config TPM_BUS_SECURITY + bool "Use secure transactions on the TPM bus" + default y + select CRYPTO_ECDH + select CRYPTO_LIB_AESCFB + select CRYPTO_LIB_SHA256 + 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 2518b675e866..dbe4a8e8cef3 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-chip.c b/drivers/char/tpm/tpm-chip.c index 741d8f3e8fb3..5577445cde53 100644 --- a/drivers/char/tpm/tpm-chip.c +++ b/drivers/char/tpm/tpm-chip.c @@ -271,6 +271,9 @@ static void tpm_dev_release(struct device *dev) kfree(chip->work_space.context_buf); kfree(chip->work_space.session_buf); kfree(chip->allocated_banks); +#ifdef CONFIG_TPM_BUS_SECURITY + kfree(chip->auth); +#endif kfree(chip); } 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..920845b9434d --- /dev/null +++ b/drivers/char/tpm/tpm2-sessions.c @@ -0,0 +1,1160 @@ +// 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 + +/* 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; + struct crypto_aes_ctx aes_ctx; + /* saved session attributes */ + u8 attrs; + __be32 ordinal; + /* 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 + SHA512_DIGEST_SIZE]; +}; + +/* + * Name Size based on TPM algorithm (assumes no hash bigger than 255) + */ +static u8 name_size(const u8 *name) +{ + static u8 size_map[] = { + [TPM_ALG_SHA1] = SHA1_DIGEST_SIZE, + [TPM_ALG_SHA256] = SHA256_DIGEST_SIZE, + [TPM_ALG_SHA384] = SHA384_DIGEST_SIZE, + [TPM_ALG_SHA512] = SHA512_DIGEST_SIZE, + }; + u16 alg = get_unaligned_be16(name); + return size_map[alg] + 2; +} + +/* + * 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 sha256_state *sctx, u8 *key, int keylen) +{ + u8 pad[SHA256_BLOCK_SIZE]; + int i; + + sha256_init(sctx); + for (i = 0; i < sizeof(pad); i++) { + if (i < keylen) + pad[i] = key[i]; + else + pad[i] = 0; + pad[i] ^= HMAC_IPAD_VALUE; + } + sha256_update(sctx, pad, sizeof(pad)); +} + +static void hmac_final(struct sha256_state *sctx, 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 */ + sha256_final(sctx, out); + + sha256_init(sctx); + sha256_update(sctx, pad, sizeof(pad)); + sha256_update(sctx, out, SHA256_DIGEST_SIZE); + sha256_final(sctx, 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) { + struct sha256_state sctx; + __be32 c = cpu_to_be32(counter); + + hmac_init(&sctx, key, keylen); + sha256_update(&sctx, (u8 *)&c, sizeof(c)); + sha256_update(&sctx, label, strlen(label)+1); + sha256_update(&sctx, u, SHA256_DIGEST_SIZE); + sha256_update(&sctx, v, SHA256_DIGEST_SIZE); + sha256_update(&sctx, (u8 *)&bits, sizeof(bits)); + hmac_final(&sctx, 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) +{ + struct sha256_state sctx; + /* + * 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); + + sha256_init(&sctx); + /* counter (BE) */ + sha256_update(&sctx, (u8 *)&c, sizeof(c)); + /* secret value */ + sha256_update(&sctx, z, EC_PT_SZ); + /* string including trailing zero */ + sha256_update(&sctx, str, strlen(str)+1); + sha256_update(&sctx, pt_u, EC_PT_SZ); + sha256_update(&sctx, pt_v, EC_PT_SZ); + sha256_final(&sctx, keyout); +} + +static void tpm_buf_append_salt(struct tpm_buf *buf, struct tpm_chip *chip) +{ + 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; + + /* 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, chip->auth->salt, 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. Note salt + * area is used both for input shared secret and output salt. + * This works because KDFe fully consumes the secret before it + * writes the salt + */ + KDFe(chip->auth->salt, "SECRET", x, chip->ec_point_x, chip->auth->salt); + out: + crypto_free_kpp(kpp); +} + +/** + * tpm_buf_append_hmac_session() append a TPM session element + * @chip: the TPM chip structure + * @buf: The buffer to be appended + * @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_chip *chip, struct tpm_buf *buf, + u8 attributes, u8 *passphrase, + int passphraselen) +{ + u8 nonce[SHA256_DIGEST_SIZE]; + u32 len; + struct tpm2_auth *auth = chip->auth; + + /* + * 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 + * @chip: the TPM chip structure + * @buf: The buffer to be appended + * + * 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_chip *chip, struct tpm_buf *buf) +{ + u32 cc, handles, val; + struct tpm2_auth *auth = chip->auth; + 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]; + struct sha256_state sctx; + + /* save the command code in BE format */ + auth->ordinal = head->ordinal; + + 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) { + u16 len; + + /* 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); + + len = tpm_get_inc_u16(&p); + aes_expandkey(&auth->aes_ctx, auth->scratch, AES_KEYBYTES); + aescfb_encrypt(&auth->aes_ctx, (u8 *)p, p, len, + auth->scratch + AES_KEYBYTES); + /* reset p to beginning of parameters for HMAC */ + p -= 2; + } + + sha256_init(&sctx); + /* ordinal is already BE */ + sha256_update(&sctx, (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) { + sha256_update(&sctx, auth->name[i], + name_size(auth->name[i])); + } else { + __be32 h = cpu_to_be32(auth->name_h[i]); + + sha256_update(&sctx, (u8 *)&h, 4); + } + } + if (buf->data - s != tpm_buf_length(buf)) + sha256_update(&sctx, s, buf->data + tpm_buf_length(buf) - s); + sha256_final(&sctx, cphash); + + /* now calculate the hmac */ + hmac_init(&sctx, auth->session_key, sizeof(auth->session_key) + + auth->passphraselen); + sha256_update(&sctx, cphash, sizeof(cphash)); + sha256_update(&sctx, auth->our_nonce, sizeof(auth->our_nonce)); + sha256_update(&sctx, auth->tpm_nonce, sizeof(auth->tpm_nonce)); + sha256_update(&sctx, &auth->attrs, 1); + hmac_final(&sctx, 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 != name_size(data)) + return -EINVAL; + memcpy(name, data, name_size(data)); + /* 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 + * @chip: the TPM chip structure + * @buf: The buffer to be appended + * @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_chip *chip, struct tpm_buf *buf, + u32 handle, u8 *name) +{ + int slot; + u8 mso = handle >> 24; + struct tpm2_auth *auth = chip->auth; + + slot = (tpm_buf_length(buf) - TPM_HEADER_SIZE)/4; + if (slot >= AUTH_MAX_NAMES) { + dev_err(&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(chip, handle, auth->name[slot]); + } else { + if (name) + dev_err(&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, name_size(name)); +} +EXPORT_SYMBOL(tpm_buf_append_name); + +/** + * tpm_buf_check_hmac_response() - check the TPM return HMAC for correctness + * @chip: the TPM chip structure + * @buf: the original command buffer (which now contains the response) + * @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_chip *chip, struct tpm_buf *buf, + int rc) +{ + struct tpm_header *head = (struct tpm_header *)buf->data; + struct tpm2_auth *auth = chip->auth; + const u8 *s, *p; + u8 rphash[SHA256_DIGEST_SIZE]; + u32 attrs; + struct sha256_state sctx; + 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 + */ + sha256_init(&sctx); + /* yes, I know this is now zero, but it's what the standard says */ + sha256_update(&sctx, (u8 *)&head->return_code, + sizeof(head->return_code)); + /* ordinal is already BE */ + sha256_update(&sctx, (u8 *)&auth->ordinal, sizeof(auth->ordinal)); + sha256_update(&sctx, p, parm_len); + sha256_final(&sctx, rphash); + + /* now calculate the hmac */ + hmac_init(&sctx, auth->session_key, sizeof(auth->session_key) + + auth->passphraselen); + sha256_update(&sctx, rphash, sizeof(rphash)); + sha256_update(&sctx, auth->tpm_nonce, sizeof(auth->tpm_nonce)); + sha256_update(&sctx, auth->our_nonce, sizeof(auth->our_nonce)); + sha256_update(&sctx, &auth->attrs, 1); + /* we're done with the rphash, so put our idea of the hmac there */ + hmac_final(&sctx, auth->session_key, sizeof(auth->session_key) + + auth->passphraselen, rphash); + if (memcmp(rphash, s, SHA256_DIGEST_SIZE) == 0) { + rc = 0; + } else { + dev_err(&chip->dev, "TPM: HMAC check failed\n"); + goto out; + } + + /* now do response decryption */ + if (auth->attrs & TPM2_SA_ENCRYPT) { + /* 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); + + len = tpm_get_inc_u16(&p); + aes_expandkey(&auth->aes_ctx, auth->scratch, AES_KEYBYTES); + aescfb_decrypt(&auth->aes_ctx, (u8 *)p, p, len, + auth->scratch + AES_KEYBYTES); + } + + out: + if ((auth->attrs & TPM2_SA_CONTINUE_SESSION) == 0 + && rc) + /* manually close the session if it wasn't consumed */ + tpm2_flush_context(chip, auth->handle); + + /* 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 + * @chip: the TPM chip structure + * + * 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 tpm_chip *chip) +{ + tpm2_flush_context(chip, chip->auth->handle); + chip->auth->session = TPM_HEADER_SIZE; +} +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 tpm_buf buf; + struct tpm2_auth *auth = chip->auth; + int rc; + unsigned int offset = 0; /* dummy offset for null seed context */ + u32 nullkey; + + rc = tpm2_load_context(chip, chip->tpmkeycontext, &offset, + &nullkey); + if (rc) + goto out; + + 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); + /* 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; + + out: + 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; + + 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 */ + put_unaligned_be16(TPM_ALG_SHA256, chip->tpmkeyname); + sha256(resp, len, 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) { + dev_err(&chip->dev, "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; +} + +static 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; + + rc = tpm2_create_null_primary(chip); + if (rc) + dev_err(&chip->dev, "TPM: security failed (NULL seed derivation): %d\n", rc); + + chip->auth = kmalloc(sizeof(*chip->auth), GFP_KERNEL); + if (!chip->auth) + return -ENOMEM; + + return rc; +} +EXPORT_SYMBOL(tpm2_sessions_init); diff --git a/include/linux/tpm.h b/include/linux/tpm.h index fa8d1f932c0f..e9ee276528de 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 +200,15 @@ struct tpm_chip { /* active locality */ int locality; + +#ifdef CONFIG_TPM_BUS_SECURITY + /* 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]; + struct tpm2_auth *auth; +#endif }; #define TPM_HEADER_SIZE 10 @@ -194,6 +233,7 @@ 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 +271,10 @@ 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 +287,7 @@ enum tpm2_command_codes { }; enum tpm2_permanent_handles { + TPM2_RH_NULL = 0x40000007, TPM2_RS_PW = 0x40000009, }; @@ -306,16 +351,30 @@ 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 +428,15 @@ 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 +467,102 @@ 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); +void tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf, + u32 handle, u8 *name); +void tpm_buf_append_hmac_session(struct tpm_chip *chip, struct tpm_buf *buf, + u8 attributes, u8 *passphrase, + int passphraselen); +static inline void tpm_buf_append_hmac_session_opt(struct tpm_chip *chip, + struct tpm_buf *buf, + u8 attributes, + u8 *passphrase, + int passphraselen) +{ + tpm_buf_append_hmac_session(chip, buf, attributes, passphrase, + passphraselen); +} +void tpm_buf_fill_hmac_session(struct tpm_chip *chip, struct tpm_buf *buf); +int tpm_buf_check_hmac_response(struct tpm_chip *chip, struct tpm_buf *buf, + int rc); +void tpm2_end_auth_session(struct tpm_chip *chip); +#else +#include + +static inline int tpm2_start_auth_session(struct tpm_chip *chip) +{ + return 0; +} +static inline void tpm2_end_auth_session(struct tpm_chip *chip) +{ +} +static inline void tpm_buf_append_name(struct tpm_chip *chip, + struct tpm_buf *buf, + u32 handle, u8 *name) +{ + tpm_buf_append_u32(buf, handle); + /* count the number of handles in the upper bits of flags */ + buf->handles++; +} +static inline void tpm_buf_append_hmac_session(struct tpm_chip *chip, + struct tpm_buf *buf, + 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_chip *chip, + struct tpm_buf *buf, + 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_chip *chip, + struct tpm_buf *buf) +{ +} +static inline int tpm_buf_check_hmac_response(struct tpm_chip *chip, + struct tpm_buf *buf, + int rc) +{ + return rc; +} +#endif /* CONFIG_TPM_BUS_SECURITY */ + #endif From patchwork Thu Feb 16 20:14:06 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 13143716 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 75738C61DA4 for ; Thu, 16 Feb 2023 20:18:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229561AbjBPUSx (ORCPT ); Thu, 16 Feb 2023 15:18:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38348 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229747AbjBPUSw (ORCPT ); Thu, 16 Feb 2023 15:18:52 -0500 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [IPv6:2607:fcd0:100:8a00::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7EA014CCB0; Thu, 16 Feb 2023 12:18:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1676578729; bh=sFMhwvzqwlDOu75+YbpIFRanc0XIbEDOxzORk5liJas=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References:From; b=ShXObklnja7UU1LmbEWwpS+SYxm91QIFSzwNrmRf84n8aUOCIYy+ioGLPtY3YAx3m Y6Ws64miTQLZG2ma/hB5HRHNvkwesWV0n47aFv0WT2udFnLuW8Zj1hJLu3YeqBGsNg tiDbdPGXWa3s7sNGAe7TEugF0LQREH7ukVWcFpDE= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 4E5C51286F6C; Thu, 16 Feb 2023 15:18:49 -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 KgSD9_3pW9_X; Thu, 16 Feb 2023 15:18:49 -0500 (EST) Received: from lingrow.int.hansenpartnership.com (unknown [153.66.160.227]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id B4D2C1286F45; Thu, 16 Feb 2023 15:18:48 -0500 (EST) From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Jarkko Sakkinen , keyrings@vger.kernel.org, Ard Biesheuvel Subject: [PATCH 08/12] tpm: add hmac checks to tpm2_pcr_extend() Date: Thu, 16 Feb 2023 15:14:06 -0500 Message-Id: <20230216201410.15010-9-James.Bottomley@HansenPartnership.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20230216201410.15010-1-James.Bottomley@HansenPartnership.com> References: <20230216201410.15010-1-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 | 27 ++++++++++----------------- 1 file changed, 10 insertions(+), 17 deletions(-) diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c index 056dad3dd5c9..ef038cc71f9c 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 +229,22 @@ 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; int rc; int i; - rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND); + rc = tpm2_start_auth_session(chip); 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(chip); + 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(chip, &buf, pcr_idx, NULL); + tpm_buf_append_hmac_session(chip, &buf, 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 +253,9 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, chip->allocated_banks[i].digest_size); } + tpm_buf_fill_hmac_session(chip, &buf); rc = tpm_transmit_cmd(chip, &buf, 0, "attempting extend a PCR value"); + rc = tpm_buf_check_hmac_response(chip, &buf, rc); tpm_buf_destroy(&buf); From patchwork Thu Feb 16 20:14:07 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 13143724 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 AC58CC61DA4 for ; Thu, 16 Feb 2023 20:19:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229611AbjBPUTb (ORCPT ); Thu, 16 Feb 2023 15:19:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38410 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229558AbjBPUTa (ORCPT ); Thu, 16 Feb 2023 15:19:30 -0500 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [IPv6:2607:fcd0:100:8a00::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 25FD416327; Thu, 16 Feb 2023 12:19:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1676578769; bh=SE6HKh3MzOkV6VQ+sdsgr/jtH0PlyVA2D5a/H+vb7Jc=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References:From; b=djbSDEkHw3jg6DAt2CNdahbb7xFCrvtTp0lNaDPKH+R581HPZSLaL5G9Bjl19D/H6 WLXPAohCLN8singYZdWnAXjXiXk15FuDfh9MGBxHEcfx1AomxcWq75I0hZNfKKRJtX i3905J2xhWgEjKQS+/UE3dSkZVL1LqhT2zEcX5AM= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id EBE4C1286F45; Thu, 16 Feb 2023 15:19:29 -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 jHep8-Cu4kMR; Thu, 16 Feb 2023 15:19:29 -0500 (EST) Received: from lingrow.int.hansenpartnership.com (unknown [153.66.160.227]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 6CB031286629; Thu, 16 Feb 2023 15:19:29 -0500 (EST) From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Jarkko Sakkinen , keyrings@vger.kernel.org, Ard Biesheuvel Subject: [PATCH 09/12] tpm: add session encryption protection to tpm2_get_random() Date: Thu, 16 Feb 2023 15:14:07 -0500 Message-Id: <20230216201410.15010-10-James.Bottomley@HansenPartnership.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20230216201410.15010-1-James.Bottomley@HansenPartnership.com> References: <20230216201410.15010-1-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 | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c index ef038cc71f9c..dc0070922d38 100644 --- a/drivers/char/tpm/tpm2-cmd.c +++ b/drivers/char/tpm/tpm2-cmd.c @@ -292,25 +292,35 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max) if (!num_bytes || max > TPM_MAX_RNG_DATA) return -EINVAL; - err = tpm_buf_init(&buf, 0, 0); + err = tpm2_start_auth_session(chip); if (err) return err; + err = tpm_buf_init(&buf, 0, 0); + if (err) { + tpm2_end_auth_session(chip); + 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(chip, &buf, TPM2_SA_ENCRYPT + | TPM2_SA_CONTINUE_SESSION, + NULL, 0); tpm_buf_append_u16(&buf, num_bytes); + tpm_buf_fill_hmac_session(chip, &buf); err = tpm_transmit_cmd(chip, &buf, offsetof(struct tpm2_get_random_out, buffer), "attempting get random"); + err = tpm_buf_check_hmac_response(chip, &buf, 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 + @@ -327,6 +337,8 @@ 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(chip); + return total ? total : -EIO; out: tpm_buf_destroy(&buf); From patchwork Thu Feb 16 20:14:08 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 13143725 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 1322BC636CC for ; Thu, 16 Feb 2023 20:20:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229588AbjBPUUr (ORCPT ); Thu, 16 Feb 2023 15:20:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40036 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229884AbjBPUUp (ORCPT ); Thu, 16 Feb 2023 15:20:45 -0500 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [IPv6:2607:fcd0:100:8a00::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B2E0653839; Thu, 16 Feb 2023 12:20:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1676578806; bh=JYbCeo+9f0NDSxEkotsgkVBUlwmOInxg30sXrzaD+5Q=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References:From; b=KgVAN7NccyUtSJw5eIZWeYxEHuiaw88dJx+bKzi+kP4JJtHzI6fHbsxCVZPsBCem1 YMdFT5RjVej17PulT4qFOqrMz8zW8kmI8+RpcYVPloemuDVkanNkHXiyikaj/zfqiX FmJOPDlproGnPBdjKL6J9gVidDqWaLEn7gZ57ZqQ= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 47E2A1286F6C; Thu, 16 Feb 2023 15:20:06 -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 ChpDX_3mM9gZ; Thu, 16 Feb 2023 15:20:06 -0500 (EST) Received: from lingrow.int.hansenpartnership.com (unknown [153.66.160.227]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id B254F1286629; Thu, 16 Feb 2023 15:20:05 -0500 (EST) From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Jarkko Sakkinen , keyrings@vger.kernel.org, Ard Biesheuvel Subject: [PATCH 10/12] KEYS: trusted: Add session encryption protection to the seal/unseal path Date: Thu, 16 Feb 2023 15:14:08 -0500 Message-Id: <20230216201410.15010-11-James.Bottomley@HansenPartnership.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20230216201410.15010-1-James.Bottomley@HansenPartnership.com> References: <20230216201410.15010-1-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 --- v2: fix unseal with policy and password v3: fix session memory leak --- security/keys/trusted-keys/trusted_tpm2.c | 82 ++++++++++++++++------- 1 file changed, 58 insertions(+), 24 deletions(-) diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c index 2b2c8eb258d5..4790aa7a1e0f 100644 --- a/security/keys/trusted-keys/trusted_tpm2.c +++ b/security/keys/trusted-keys/trusted_tpm2.c @@ -252,18 +252,19 @@ int tpm2_seal_trusted(struct tpm_chip *chip, if (rc) return rc; + rc = tpm2_start_auth_session(chip); + 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(chip); + 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(chip, &buf, options->keyhandle, NULL); + tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_DECRYPT, + options->keyauth, TPM_DIGEST_SIZE); /* sensitive */ tpm_buf_append_u16(&buf, 4 + options->blobauth_len + payload->key_len); @@ -305,10 +306,13 @@ int tpm2_seal_trusted(struct tpm_chip *chip, if (buf.flags & TPM_BUF_OVERFLOW) { rc = -E2BIG; + tpm2_end_auth_session(chip); goto out; } + tpm_buf_fill_hmac_session(chip, &buf); rc = tpm_transmit_cmd(chip, &buf, 4, "sealing data"); + rc = tpm_buf_check_hmac_response(chip, &buf, rc); if (rc) goto out; @@ -340,6 +344,7 @@ int tpm2_seal_trusted(struct tpm_chip *chip, else payload->blob_len = blob_len; +out_put: tpm_put_ops(chip); return rc; } @@ -409,25 +414,31 @@ 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); 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(chip); + return rc; + } + + tpm_buf_append_name(chip, &buf, options->keyhandle, NULL); + tpm_buf_append_hmac_session(chip, &buf, 0, options->keyauth, + TPM_DIGEST_SIZE); tpm_buf_append(&buf, blob, blob_len); if (buf.flags & TPM_BUF_OVERFLOW) { rc = -E2BIG; + tpm2_end_auth_session(chip); goto out; } + tpm_buf_fill_hmac_session(chip, &buf); rc = tpm_transmit_cmd(chip, &buf, 4, "loading blob"); + rc = tpm_buf_check_hmac_response(chip, &buf, rc); if (!rc) *blob_handle = be32_to_cpup( (__be32 *) &buf.data[TPM_HEADER_SIZE]); @@ -465,20 +476,43 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip, u8 *data; int rc; - rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL); + rc = tpm2_start_auth_session(chip); 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(chip); + return rc; + } + + tpm_buf_append_name(chip, &buf, blob_handle, NULL); + + if (!options->policyhandle) { + tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_ENCRYPT, + options->blobauth, TPM_DIGEST_SIZE); + } else { + /* + * FIXME: The policy session was generated outside the + * kernel so we don't known the nonce and thus can't + * calculate a HMAC on it. Therefore, the user can + * only really use TPM2_PolicyPassword and we must + * send down the plain text password, which could be + * intercepted. We can still encrypt the returned + * key, but that's small comfort since the interposer + * could repeat our actions with the exfiltrated + * password. + */ + tpm2_buf_append_auth(&buf, options->policyhandle, + NULL /* nonce */, 0, 0, + options->blobauth, options->blobauth_len); + tpm_buf_append_hmac_session_opt(chip, &buf, TPM2_SA_ENCRYPT, + NULL, 0); + } + tpm_buf_fill_hmac_session(chip, &buf); rc = tpm_transmit_cmd(chip, &buf, 6, "unsealing"); + rc = tpm_buf_check_hmac_response(chip, &buf, rc); if (rc > 0) rc = -EPERM; From patchwork Thu Feb 16 20:40:15 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 13143808 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 946ADC61DA4 for ; Thu, 16 Feb 2023 20:40:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229513AbjBPUkT (ORCPT ); Thu, 16 Feb 2023 15:40:19 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53524 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229492AbjBPUkS (ORCPT ); Thu, 16 Feb 2023 15:40:18 -0500 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [96.44.175.130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7D1781CF49; Thu, 16 Feb 2023 12:40:17 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1676580017; bh=5EwqDN+hWjx/K2/3gSzoNXkyvfn5rpW6z/3xwTv17Hc=; h=Message-ID:Subject:From:To:Date:In-Reply-To:References:From; b=ELYEppL7YyFVWGPeX3wxiwqAV4TUh3XlQ48Q2/YvHbwS9jyLWSddAgf/8w6pPq5T0 UU90yZff3MgYcr+8B6WZGuTUvCIMVQTgDw1DHUMhL1oynNZR+DPqnDxxfjqD7JDkzJ 0VK/XV01E8NQMgSoQk+mg6aId5BHWbI7coAmH408= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 345A3128142B; Thu, 16 Feb 2023 15:40:17 -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 Rh-qOGgXOl3T; Thu, 16 Feb 2023 15:40:17 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1676580016; bh=5EwqDN+hWjx/K2/3gSzoNXkyvfn5rpW6z/3xwTv17Hc=; h=Message-ID:Subject:From:To:Date:In-Reply-To:References:From; b=xTQ6PsxBG0Ow3nmYxQx7xGmR+8SiGkCMeksua49o3+Qy0lg2JeetJPc5bRQCMA4gD fy2FdR6gvmQ7qCg7mjcJIC8N8tmTNRVmHyhfABTyYdGJ42K9EAvXAwuqAdlVvWKeM6 7qPyxRynyBgEoKgSD5GSBv/wloMyH8Sovrga5D6w= Received: from lingrow.int.hansenpartnership.com (unknown [IPv6:2601:5c4:4302:c21::c14]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (prime256v1) server-signature RSA-PSS (2048 bits) server-digest SHA256) (Client did not present a certificate) by bedivere.hansenpartnership.com (Postfix) with ESMTPSA id 8B0F41280E69; Thu, 16 Feb 2023 15:40:16 -0500 (EST) Message-ID: <93740b6b42e67caa2a1854520b7e68f0966e5024.camel@HansenPartnership.com> Subject: [PATCH 11/12] tpm: add the null key name as a sysfs export From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Jarkko Sakkinen , keyrings@vger.kernel.org, Ard Biesheuvel Date: Thu, 16 Feb 2023 15:40:15 -0500 In-Reply-To: <20230216201410.15010-1-James.Bottomley@HansenPartnership.com> References: <20230216201410.15010-1-James.Bottomley@HansenPartnership.com> User-Agent: Evolution 3.42.4 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 | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c index 54c71473aa29..6044a2765da2 100644 --- a/drivers/char/tpm/tpm-sysfs.c +++ b/drivers/char/tpm/tpm-sysfs.c @@ -309,6 +309,21 @@ static ssize_t tpm_version_major_show(struct device *dev, } static DEVICE_ATTR_RO(tpm_version_major); +#ifdef CONFIG_TPM_BUS_SECURITY +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); +#endif + static struct attribute *tpm1_dev_attrs[] = { &dev_attr_pubek.attr, &dev_attr_pcrs.attr, @@ -326,6 +341,9 @@ static struct attribute *tpm1_dev_attrs[] = { static struct attribute *tpm2_dev_attrs[] = { &dev_attr_tpm_version_major.attr, +#if CONFIG_TPM_BUS_SECURITY + &dev_attr_null_name.attr, +#endif NULL }; From patchwork Thu Feb 16 20:41:04 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 13143809 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 77D45C61DA4 for ; Thu, 16 Feb 2023 20:41:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229556AbjBPUlJ (ORCPT ); Thu, 16 Feb 2023 15:41:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53804 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229508AbjBPUlI (ORCPT ); Thu, 16 Feb 2023 15:41:08 -0500 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [IPv6:2607:fcd0:100:8a00::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AD9021CF49; Thu, 16 Feb 2023 12:41:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1676580066; bh=X0Q0v99eN2KxDgCMEZHqzTucfel3h4EGsfBLUoiMmnw=; h=Message-ID:Subject:From:To:Date:In-Reply-To:References:From; b=RAwkGtvp+ZKSr++pFNmnbfkSWNmOvS7XYpIru5Jc2232sdP/CyagyShy7dhyouSzJ 8TWsDMQ8FdHWUG2rzUCnfJ/JupTqfIlmSyEu8ACHxqjy44HaZmWYxzcsjejOHPqpTY giCK9nCLn0KPS1lVBdjbTVwM+qkaWlYKycXJ2588= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 588A7128142B; Thu, 16 Feb 2023 15:41:06 -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 ILMPdvsN6LZ6; Thu, 16 Feb 2023 15:41:06 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1676580066; bh=X0Q0v99eN2KxDgCMEZHqzTucfel3h4EGsfBLUoiMmnw=; h=Message-ID:Subject:From:To:Date:In-Reply-To:References:From; b=RAwkGtvp+ZKSr++pFNmnbfkSWNmOvS7XYpIru5Jc2232sdP/CyagyShy7dhyouSzJ 8TWsDMQ8FdHWUG2rzUCnfJ/JupTqfIlmSyEu8ACHxqjy44HaZmWYxzcsjejOHPqpTY giCK9nCLn0KPS1lVBdjbTVwM+qkaWlYKycXJ2588= Received: from lingrow.int.hansenpartnership.com (unknown [IPv6:2601:5c4:4302:c21::c14]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (prime256v1) server-signature RSA-PSS (2048 bits)) (Client did not present a certificate) by bedivere.hansenpartnership.com (Postfix) with ESMTPSA id A16171280E69; Thu, 16 Feb 2023 15:41:05 -0500 (EST) Message-ID: Subject: [PATCH 12/12] Documentation: add tpm-security.rst From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Jarkko Sakkinen , keyrings@vger.kernel.org, Ard Biesheuvel Date: Thu, 16 Feb 2023 15:41:04 -0500 In-Reply-To: <20230216201410.15010-1-James.Bottomley@HansenPartnership.com> References: <20230216201410.15010-1-James.Bottomley@HansenPartnership.com> User-Agent: Evolution 3.42.4 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 | 216 ++++++++++++++++++++ 1 file changed, 216 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..4f633f251033 --- /dev/null +++ b/Documentation/security/tpm/tpm-security.rst @@ -0,0 +1,216 @@ +.. SPDX-License-Identifier: GPL-2.0-only + +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/