1 files changed, 101 insertions, 0 deletions
diff --git a/firmware/bdb/secrets.c b/firmware/bdb/secrets.c
new file mode 100644
index 00000000..08bca5f5
--- /dev/null
+++ b/firmware/bdb/secrets.c
@@ -0,0 +1,101 @@
+/* Copyright 2016 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.
+ */
+
+#include "2sysincludes.h"
+#include "2hmac.h"
+#include "2sha.h"
+#include "bdb_api.h"
+#include "bdb_struct.h"
+#include "bdb.h"
+#include "secrets.h"
+
+static int get_constant(const uint8_t *buf, uint32_t buf_size,
+			const uint8_t *constant, uint8_t *out)
+{
+	int digest_size = vb2_digest_size(VB2_HASH_SHA256);
+	const struct bdb_key *key = (const struct bdb_key *)buf;
+
+	if (!buf)
+		return !BDB_SUCCESS;
+
+	if (bdb_check_key(key, buf_size))
+		return !BDB_SUCCESS;
+
+	if (vb2_digest_buffer(buf, buf_size, VB2_HASH_SHA256, out, digest_size))
+		return !BDB_SUCCESS;
+
+	memcpy(out + digest_size, constant,
+	       BDB_CONSTANT_BLOCK_SIZE - digest_size);
+
+	return BDB_SUCCESS;
+}
+
+int vba_derive_secret(struct vba_context *ctx, enum bdb_secret_type type,
+		      const uint8_t *buf, uint32_t buf_size)
+{
+	uint8_t c[BDB_CONSTANT_BLOCK_SIZE];
+	const uint8_t *b = (const uint8_t *)c;
+	uint8_t *s;
+	uint8_t *o;
+
+	switch (type) {
+	case BDB_SECRET_TYPE_BDB:
+		s = o = ctx->ro_secrets->bdb;
+		if (get_constant(buf, buf_size, secret_constant_q, c))
+			return BDB_ERROR_SECRET_BDB;
+		break;
+	case BDB_SECRET_TYPE_BOOT_PATH:
+		s = o = ctx->ro_secrets->boot_path;
+		if (get_constant(buf, buf_size, secret_constant_l, c))
+			return BDB_ERROR_SECRET_BOOT_PATH;
+		break;
+	case BDB_SECRET_TYPE_BOOT_VERIFIED:
+		s = o = ctx->ro_secrets->boot_verified;
+		if (ctx->flags & VBA_CONTEXT_FLAG_KERNEL_DATA_KEY_VERIFIED)
+			b = secret_constant_kv1;
+		else
+			b = secret_constant_kv0;
+		break;
+	case BDB_SECRET_TYPE_BUC:
+		s = ctx->ro_secrets->boot_verified;
+		b = secret_constant_c;
+		o = ctx->rw_secrets->buc;
+		break;
+	default:
+		return BDB_ERROR_SECRET_TYPE;
+	}
+
+	vb2_sha256_extend(s, b, o);
+
+	return BDB_SUCCESS;
+}
+
+int vba_clear_secret(struct vba_context *ctx, enum bdb_secret_type type)
+{
+	uint8_t *s;
+
+	switch (type) {
+	case BDB_SECRET_TYPE_NVM_RW:
+		s = ctx->ro_secrets->nvm_rw;
+		break;
+	case BDB_SECRET_TYPE_BDB:
+		s = ctx->ro_secrets->bdb;
+		break;
+	case BDB_SECRET_TYPE_BOOT_PATH:
+		s = ctx->ro_secrets->boot_path;
+		break;
+	case BDB_SECRET_TYPE_BOOT_VERIFIED:
+		s = ctx->ro_secrets->boot_verified;
+		break;
+	case BDB_SECRET_TYPE_BUC:
+		s = ctx->rw_secrets->buc;
+		break;
+	default:
+		return BDB_ERROR_SECRET_TYPE;
+	}
+
+	memset(s, 0, BDB_SECRET_SIZE);
+	return BDB_SUCCESS;
+}