From 48784d452a85ee282823d1d8c8d3d4eec56de3a2 Mon Sep 17 00:00:00 2001
From: Martin Kepplinger <martink@posteo.de>
Date: Wed, 15 May 2019 11:55:24 +0200
Subject: [PATCH] Add Heads TPM measured boot support

Change-Id: I3a64998de2fbb7f2059cb8c68cfbf949b0665665
Signed-off-by: Martin Kepplinger <martink@posteo.de>
---
 src/Kconfig                        |  15 +++
 src/include/program_loading.h      |   2 +
 src/lib/cbfs.c                     |  19 ++-
 src/lib/hardwaremain.c             |   8 ++
 src/lib/rmodule.c                  |   3 +-
 src/security/tpm/Makefile.inc      |   5 +
 src/security/tpm/sha1.c            | 180 +++++++++++++++++++++++++++++
 src/security/tpm/sha1.h            |  47 ++++++++
 src/security/tpm/tspi/tspi.c       |   2 +-
 src/security/tpm/tss.h             |   5 +
 src/security/tpm/tss/tcg-1.2/tss.c |  19 +++
 11 files changed, 299 insertions(+), 6 deletions(-)
 create mode 100644 src/security/tpm/sha1.c
 create mode 100644 src/security/tpm/sha1.h

diff --git a/src/Kconfig b/src/Kconfig
index c0315239fc..48e53dc239 100644
--- a/src/Kconfig
+++ b/src/Kconfig
@@ -332,6 +332,21 @@ config BOOTSPLASH_FILE
 config HAVE_RAMPAYLOAD
 	bool
 
+config MEASURED_BOOT
+	bool "Enable TPM measured boot"
+	default n
+	select TPM1
+	depends on MAINBOARD_HAS_LPC_TPM
+	depends on !VBOOT
+	help
+	  Enable this option to measure the bootblock, romstage and
+	  CBFS files into TPM PCRs.  This does not verify these values
+	  (that is the job of something like vboot), but makes it possible
+	  for the payload to validate the boot path and allow something
+	  like Heads to attest to the user that the system is likely safe.
+
+	  You probably want to say N.
+
 config RAMPAYLOAD
 	bool "Enable coreboot flow without executing ramstage"
 	default y if ARCH_X86
diff --git a/src/include/program_loading.h b/src/include/program_loading.h
index 1b71fadb1b..afd8ba0c54 100644
--- a/src/include/program_loading.h
+++ b/src/include/program_loading.h
@@ -26,6 +26,8 @@ enum {
 	/* Last segment of program. Can be used to take different actions for
 	 * cache maintenance of a program load. */
 	SEG_FINAL = 1 << 0,
+	/* Indicate that the program segment should not be measured */
+	SEG_NO_MEASURE = 1 << 1,
 };
 
 enum prog_type {
diff --git a/src/lib/cbfs.c b/src/lib/cbfs.c
index fbe6e43496..b0a4f8843a 100644
--- a/src/lib/cbfs.c
+++ b/src/lib/cbfs.c
@@ -97,7 +97,13 @@ void *cbfs_boot_map_with_leak(const char *name, uint32_t type, size_t *size)
 	if (size != NULL)
 		*size = fsize;
 
-	return rdev_mmap(&fh.data, 0, fsize);
+	void *buffer = rdev_mmap(&fh.data, 0, fsize);
+
+#ifndef __SMM__
+	prog_segment_loaded((uintptr_t)buffer, fsize, 0);
+#endif
+
+	return buffer;
 }
 
 int cbfs_locate_file_in_region(struct cbfsf *fh, const char *region_name,
@@ -125,7 +131,8 @@ size_t cbfs_load_and_decompress(const struct region_device *rdev, size_t offset,
 			return 0;
 		if (rdev_readat(rdev, buffer, offset, in_size) != in_size)
 			return 0;
-		return in_size;
+		out_size = in_size;
+		break;
 
 	case CBFS_COMPRESS_LZ4:
 		if ((ENV_BOOTBLOCK || ENV_VERSTAGE) &&
@@ -143,7 +150,7 @@ size_t cbfs_load_and_decompress(const struct region_device *rdev, size_t offset,
 		timestamp_add_now(TS_START_ULZ4F);
 		out_size = ulz4fn(compr_start, in_size, buffer, buffer_size);
 		timestamp_add_now(TS_END_ULZ4F);
-		return out_size;
+		break;
 
 	case CBFS_COMPRESS_LZMA:
 		/* We assume here romstage and postcar are never compressed. */
@@ -165,11 +172,15 @@ size_t cbfs_load_and_decompress(const struct region_device *rdev, size_t offset,
 
 		rdev_munmap(rdev, map);
 
-		return out_size;
+		break;
 
 	default:
 		return 0;
 	}
+
+	prog_segment_loaded((uintptr_t)buffer, out_size, 0);
+
+	return out_size;
 }
 
 static inline int tohex4(unsigned int c)
diff --git a/src/lib/hardwaremain.c b/src/lib/hardwaremain.c
index 51ff330d84..358d3e40b3 100644
--- a/src/lib/hardwaremain.c
+++ b/src/lib/hardwaremain.c
@@ -32,6 +32,7 @@
 #include <stdlib.h>
 #include <boot/tables.h>
 #include <program_loading.h>
+#include <security/tpm/tss.h>
 #if CONFIG(HAVE_ACPI_RESUME)
 #include <arch/acpi.h>
 #endif
@@ -540,3 +541,10 @@ void boot_state_current_unblock(void)
 {
 	boot_state_unblock(current_phase.state_id, current_phase.seq);
 }
+
+// ramstage measurements go into PCR3 if we are doing measured boot
+void platform_segment_loaded(uintptr_t start, size_t size, int flags)
+{
+	if (CONFIG(MEASURED_BOOT) && !(flags & SEG_NO_MEASURE))
+		tlcl_measure(2, (const void *) start, size);
+}
diff --git a/src/lib/rmodule.c b/src/lib/rmodule.c
index 56529d2fb2..2702b9d36e 100644
--- a/src/lib/rmodule.c
+++ b/src/lib/rmodule.c
@@ -197,7 +197,8 @@ int rmodule_load(void *base, struct rmodule *module)
 	rmodule_clear_bss(module);
 
 	prog_segment_loaded((uintptr_t)module->location,
-				rmodule_memory_size(module), SEG_FINAL);
+			    rmodule_memory_size(module),
+			    SEG_FINAL | SEG_NO_MEASURE);
 
 	return 0;
 }
diff --git a/src/security/tpm/Makefile.inc b/src/security/tpm/Makefile.inc
index a2d32cff89..e9a785b797 100644
--- a/src/security/tpm/Makefile.inc
+++ b/src/security/tpm/Makefile.inc
@@ -18,6 +18,11 @@ romstage-y += tspi/tspi.c
 verstage-$(CONFIG_VBOOT) += tspi/tspi.c
 postcar-$(CONFIG_VBOOT) += tspi/tspi.c
 
+ifeq ($(CONFIG_MEASURED_BOOT),y)
+romstage-y += sha1.c
+ramstage-y += sha1.c
+endif # CONFIG_MEASURED_BOOT
+
 ramstage-$(CONFIG_VBOOT_MEASURED_BOOT) += tspi/log.c
 romstage-$(CONFIG_VBOOT_MEASURED_BOOT) += tspi/log.c
 verstage-$(CONFIG_VBOOT_MEASURED_BOOT) += tspi/log.c
diff --git a/src/security/tpm/sha1.c b/src/security/tpm/sha1.c
new file mode 100644
index 0000000000..9879f729b1
--- /dev/null
+++ b/src/security/tpm/sha1.c
@@ -0,0 +1,180 @@
+/* Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * SHA-1 implementation largely based on libmincrypt in the the Android
+ * Open Source Project (platorm/system/core.git/libmincrypt/sha.c
+ */
+
+#include <security/tpm/sha1.h>
+#include <string.h>
+
+static uint32_t ror27(uint32_t val)
+{
+	return (val >> 27) | (val << 5);
+}
+static uint32_t ror2(uint32_t val)
+{
+	return (val >> 2) | (val << 30);
+}
+static uint32_t ror31(uint32_t val)
+{
+	return (val >> 31) | (val << 1);
+}
+
+static void sha1_transform(struct sha1_ctx *ctx)
+{
+	uint32_t W[80];
+	register uint32_t A, B, C, D, E;
+	int t;
+
+	A = ctx->state[0];
+	B = ctx->state[1];
+	C = ctx->state[2];
+	D = ctx->state[3];
+	E = ctx->state[4];
+
+#define SHA_F1(A, B, C, D, E, t) do {					\
+	E += ror27(A) +							\
+			(W[t] = __builtin_bswap32(ctx->buf.w[t])) +	\
+			(D^(B&(C^D))) + 0x5A827999;			\
+	B = ror2(B);							\
+	} while (0)
+
+	for (t = 0; t < 15; t += 5) {
+		SHA_F1(A, B, C, D, E, t + 0);
+		SHA_F1(E, A, B, C, D, t + 1);
+		SHA_F1(D, E, A, B, C, t + 2);
+		SHA_F1(C, D, E, A, B, t + 3);
+		SHA_F1(B, C, D, E, A, t + 4);
+	}
+	SHA_F1(A, B, C, D, E, t + 0);  /* 16th one, t == 15 */
+
+#undef SHA_F1
+
+#define SHA_F1(A, B, C, D, E, t) do {					      \
+	E += ror27(A) +							      \
+			(W[t] = ror31(W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16])) + \
+			(D^(B&(C^D))) + 0x5A827999;			      \
+	B = ror2(B);							      \
+	} while (0)
+
+	SHA_F1(E, A, B, C, D, t + 1);
+	SHA_F1(D, E, A, B, C, t + 2);
+	SHA_F1(C, D, E, A, B, t + 3);
+	SHA_F1(B, C, D, E, A, t + 4);
+
+#undef SHA_F1
+
+#define SHA_F2(A, B, C, D, E, t) do {					      \
+	E += ror27(A) +							      \
+			(W[t] = ror31(W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16])) + \
+			(B^C^D) + 0x6ED9EBA1;				      \
+	B = ror2(B);							      \
+	} while (0)
+
+	for (t = 20; t < 40; t += 5) {
+		SHA_F2(A, B, C, D, E, t + 0);
+		SHA_F2(E, A, B, C, D, t + 1);
+		SHA_F2(D, E, A, B, C, t + 2);
+		SHA_F2(C, D, E, A, B, t + 3);
+		SHA_F2(B, C, D, E, A, t + 4);
+	}
+
+#undef SHA_F2
+
+#define SHA_F3(A, B, C, D, E, t) do {					      \
+	E += ror27(A) +							      \
+			(W[t] = ror31(W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16])) + \
+			((B&C)|(D&(B|C))) + 0x8F1BBCDC;			      \
+	B = ror2(B);							      \
+	} while (0)
+
+	for (; t < 60; t += 5) {
+		SHA_F3(A, B, C, D, E, t + 0);
+		SHA_F3(E, A, B, C, D, t + 1);
+		SHA_F3(D, E, A, B, C, t + 2);
+		SHA_F3(C, D, E, A, B, t + 3);
+		SHA_F3(B, C, D, E, A, t + 4);
+	}
+
+#undef SHA_F3
+
+#define SHA_F4(A, B, C, D, E, t) do {					      \
+	E += ror27(A) +							      \
+			(W[t] = ror31(W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16])) + \
+			(B^C^D) + 0xCA62C1D6;				      \
+	B = ror2(B);							      \
+	} while (0)
+
+	for (; t < 80; t += 5) {
+		SHA_F4(A, B, C, D, E, t + 0);
+		SHA_F4(E, A, B, C, D, t + 1);
+		SHA_F4(D, E, A, B, C, t + 2);
+		SHA_F4(C, D, E, A, B, t + 3);
+		SHA_F4(B, C, D, E, A, t + 4);
+	}
+
+#undef SHA_F4
+
+	ctx->state[0] += A;
+	ctx->state[1] += B;
+	ctx->state[2] += C;
+	ctx->state[3] += D;
+	ctx->state[4] += E;
+}
+
+void sha1_update(struct sha1_ctx *ctx, const uint8_t *data, uint32_t len)
+{
+	int i = ctx->count % sizeof(ctx->buf);
+	const uint8_t *p = (const uint8_t *)data;
+
+	ctx->count += len;
+
+	while (len > sizeof(ctx->buf) - i) {
+		memcpy(&ctx->buf.b[i], p, sizeof(ctx->buf) - i);
+		len -= sizeof(ctx->buf) - i;
+		p += sizeof(ctx->buf) - i;
+		sha1_transform(ctx);
+		i = 0;
+	}
+
+	while (len--) {
+		ctx->buf.b[i++] = *p++;
+		if (i == sizeof(ctx->buf)) {
+			sha1_transform(ctx);
+			i = 0;
+		}
+	}
+}
+
+
+uint8_t *sha1_final(struct sha1_ctx *ctx)
+{
+	uint32_t cnt = ctx->count * 8;
+	int i;
+
+	sha1_update(ctx, (uint8_t *)"\x80", 1);
+	while ((ctx->count % sizeof(ctx->buf)) != (sizeof(ctx->buf) - 8))
+		sha1_update(ctx, (uint8_t *)"\0", 1);
+
+	for (i = 0; i < 8; ++i) {
+		uint8_t tmp = cnt >> ((7 - i) * 8);
+		sha1_update(ctx, &tmp, 1);
+	}
+
+	for (i = 0; i < 5; i++)
+		ctx->buf.w[i] = __builtin_bswap32(ctx->state[i]);
+
+	return ctx->buf.b;
+}
+
+void sha1_init(struct sha1_ctx *ctx)
+{
+	ctx->state[0] = 0x67452301;
+	ctx->state[1] = 0xEFCDAB89;
+	ctx->state[2] = 0x98BADCFE;
+	ctx->state[3] = 0x10325476;
+	ctx->state[4] = 0xC3D2E1F0;
+	ctx->count = 0;
+}
diff --git a/src/security/tpm/sha1.h b/src/security/tpm/sha1.h
new file mode 100644
index 0000000000..bc3faa58ea
--- /dev/null
+++ b/src/security/tpm/sha1.h
@@ -0,0 +1,47 @@
+/* Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/* SHA-1 functions */
+
+#ifndef _sha1_h_
+#define _sha1_h_
+
+#include <stdint.h>
+#include <commonlib/helpers.h>
+
+#define SHA1_DIGEST_SIZE 20
+#define SHA1_BLOCK_SIZE 64
+
+/*
+ * FIXME the DIV_ROUND_UP statement expression blows up here:
+	In file included from src/security/tpm/sha1.h:12,
+			 from src/security/tpm/sha1.c:9:
+	src/commonlib/include/commonlib/helpers.h:81:28: error: braced-group
+		within expression allowed only inside a function
+	 #define DIV_ROUND_UP(x, y) ({ \
+				    ^
+	src/security/tpm/sha1.h:23:14: note: in expansion of macro'DIV_ROUND_UP'
+	   uint32_t w[DIV_ROUND_UP(SHA1_BLOCK_SIZE, sizeof(uint32_t))];
+		      ^~~~~~~~~~~~
+	make[1]: *** [Makefile:356: x230/romstage/security/tpm/sha1.o] Error 1
+ */
+#undef DIV_ROUND_UP
+#define DIV_ROUND_UP(x, y) (((x) + (y) - 1) / (y))
+
+/* SHA-1 context */
+struct sha1_ctx {
+	uint32_t count;
+	uint32_t state[5];
+	union {
+		uint8_t b[SHA1_BLOCK_SIZE];
+		uint32_t w[DIV_ROUND_UP(SHA1_BLOCK_SIZE, sizeof(uint32_t))];
+	} buf;
+};
+
+void sha1_init(struct sha1_ctx *ctx);
+void sha1_update(struct sha1_ctx *ctx, const uint8_t *data, uint32_t len);
+uint8_t *sha1_final(struct sha1_ctx *ctx);
+
+#endif  /* _sha1_h_ */
diff --git a/src/security/tpm/tspi/tspi.c b/src/security/tpm/tspi/tspi.c
index 966b8b7c77..9076ced37a 100644
--- a/src/security/tpm/tspi/tspi.c
+++ b/src/security/tpm/tspi/tspi.c
@@ -20,8 +20,8 @@
 #include <security/tpm/tspi.h>
 #include <security/tpm/tss.h>
 #include <stdlib.h>
-#if CONFIG(VBOOT)
 #include <vb2_api.h>
+#if CONFIG(VBOOT)
 #include <vb2_sha.h>
 #include <assert.h>
 #endif
diff --git a/src/security/tpm/tss.h b/src/security/tpm/tss.h
index 336935d911..90a96621ed 100644
--- a/src/security/tpm/tss.h
+++ b/src/security/tpm/tss.h
@@ -52,6 +52,11 @@ uint32_t tlcl_get_flags(uint8_t *disable, uint8_t *deactivated,
  */
 uint32_t tlcl_get_permanent_flags(TPM_PERMANENT_FLAGS *pflags);
 
+/**
+ * Perform a SHA1 hash on a region and extend a PCR with the hash.
+ */
+uint32_t tlcl_measure(int pcr_num, const void *start, size_t len);
+
 #endif
 
 #if CONFIG(TPM2)
diff --git a/src/security/tpm/tss/tcg-1.2/tss.c b/src/security/tpm/tss/tcg-1.2/tss.c
index b11d6a3d16..ef4f4d8b86 100644
--- a/src/security/tpm/tss/tcg-1.2/tss.c
+++ b/src/security/tpm/tss/tcg-1.2/tss.c
@@ -17,6 +17,7 @@
 #include <arch/early_variables.h>
 #include <assert.h>
 #include <string.h>
+#include <security/tpm/sha1.h>
 #include <security/tpm/tis.h>
 #include <vb2_api.h>
 #include <security/tpm/tss.h>
@@ -361,3 +362,21 @@ uint32_t tlcl_extend(int pcr_num, const uint8_t *in_digest,
 		       kPcrDigestLength);
 	return result;
 }
+
+uint32_t tlcl_measure(int pcr_num, const void *start, size_t len)
+{
+	VBDEBUG("TPM: pcr %d measure %p @ %zu: ", pcr_num, start, len);
+
+	struct sha1_ctx sha;
+	sha1_init(&sha);
+	sha1_update(&sha, start, len);
+
+	const uint8_t *hash = sha1_final(&sha);
+	for (unsigned int i = 0; i < SHA1_DIGEST_SIZE; i++)
+		VBDEBUG("%02x", hash[i]);
+	VBDEBUG("\n");
+
+	//hexdump(start, 128);
+
+	return tlcl_extend(pcr_num, hash, NULL);
+}
-- 
2.20.1

