common: Split rwsig parts from rsa.h header

We're going to add more rwsig-related functions, and adding them
to rsa.h seems increasingly incorrect.

BRANCH=none
BUG=b:35587171
TEST=make buildall -j

Change-Id: I334c1774ce9a6ed8e219140f65ebe94d653e22d2
Reviewed-on: https://chromium-review.googlesource.com/468708
Commit-Ready: Nicolas Boichat <drinkcat@chromium.org>
Tested-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>

1 files changed, 78 insertions, 0 deletions

diff --git a/include/rwsig.h b/include/rwsig.h
new file mode 100644
index 0000000000..138751d3cc
--- /dev/null
+++ b/include/rwsig.h
@@ -0,0 +1,78 @@
+/* Copyright 2017 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.
+ */
+
+#ifndef __CROS_EC_RWSIG_H
+#define __CROS_EC_RWSIG_H
+
+#include "config.h"
+#include "rsa.h"
+
+#ifndef __ASSEMBLER__
+
+/* Checks RW signature. */
+void check_rw_signature(void);
+
+#endif /* !__ASSEMBLER__ */
+
+/*
+ * The signer puts the public key and signature into the RO and RW images
+ * (respectively) at known locations after the complete image is assembled. But
+ * since we compile the RO & RW images separately, the other image's addresses
+ * can't be computed by the linker. So we just hardcode the addresses here.
+ * These can be overridden in board.h files if desired.
+ */
+
+#ifndef CONFIG_RO_PUBKEY_SIZE
+#ifdef CONFIG_RWSIG_TYPE_RWSIG
+/*
+ * rwsig type: 1024 bytes is enough to fit RSA-3072 public key.
+ *
+ * TODO(crosbug.com/p/62321): This still wastes space. We could pack the key at
+ * any arbitrary location, but we need proper signer support to make sure it
+ * can overwrite the key correctly.
+ */
+#define CONFIG_RO_PUBKEY_SIZE 1024
+#else
+#define CONFIG_RO_PUBKEY_SIZE RSA_PUBLIC_KEY_SIZE
+#endif
+#endif /* ! CONFIG_RO_PUBKEY_SIZE */
+#ifndef CONFIG_RO_PUBKEY_ADDR
+#ifdef CONFIG_RWSIG_TYPE_RWSIG
+/* The pubkey goes at the end of the RO region */
+#define CONFIG_RO_PUBKEY_ADDR (CONFIG_PROGRAM_MEMORY_BASE	\
+			       + CONFIG_RO_MEM_OFF		\
+			       + CONFIG_RO_SIZE			\
+			       - CONFIG_RO_PUBKEY_SIZE)
+#else
+/*
+ * usbpd1 type assumes pubkey location at the end of first half of flash,
+ * which might actually be in the PSTATE region.
+ */
+#define CONFIG_RO_PUBKEY_ADDR (CONFIG_PROGRAM_MEMORY_BASE	\
+			       + (CONFIG_FLASH_SIZE / 2)	\
+			       - CONFIG_RO_PUBKEY_SIZE)
+#endif
+#endif /* CONFIG_RO_PUBKEY_ADDR */
+
+#ifndef CONFIG_RW_SIG_SIZE
+#ifdef CONFIG_RWSIG_TYPE_RWSIG
+/*
+ * rwsig type: futility expects signature to be 1024 bytes from the end of
+ * the file.
+ */
+#define CONFIG_RW_SIG_SIZE 1024
+#else
+#define CONFIG_RW_SIG_SIZE RSANUMBYTES
+#endif
+#endif /* ! CONFIG_RW_SIG_SIZE */
+#ifndef CONFIG_RW_SIG_ADDR
+/* The signature goes at the end of the RW region */
+#define CONFIG_RW_SIG_ADDR (CONFIG_PROGRAM_MEMORY_BASE	\
+			    + CONFIG_RW_MEM_OFF		\
+			    + CONFIG_RW_SIZE		\
+			    - CONFIG_RW_SIG_SIZE)
+#endif /* !CONFIG_RW_SIG_ADDR */
+
+#endif /* __CROS_EC_RWSIG_H */