bootstd: cros: Bring in some ChromiumOS structures

Add a header file with structures for booting ChromiumOS, taken from the
vboot tree. Using these makes it easier to understand the code.

Note that the code style has not been updated for U-Boot, with use of
uint64_t,  __attribute__((packed)) and one comment-style nit. This should
make it easier to keep the code in sync. It was taken from commit:

   5b8596ce ("2sha256_arm: Fix data abort issue")

Update the CHROMEOS string to use the defined values.

Signed-off-by: Simon Glass <sjg@chromium.org>

diff --git a/boot/bootmeth_cros.c b/boot/bootmeth_cros.c
index f6fb521f206585599970d1d33ca20006cb69b098..385eca37381c504e05cbb537f1cc35c5c0515ba1 100644 (file)
--- a/boot/bootmeth_cros.c
+++ b/boot/bootmeth_cros.c
@@ -21,6 +21,7 @@
 #include <asm/zimage.h>
 #endif
 #include <linux/sizes.h>
+#include "bootmeth_cros.h"
 
 enum {
        PROBE_SIZE      = SZ_4K,        /* initial bytes read from partition */
@@ -82,7 +83,8 @@ static int copy_cmdline(const char *from, const char *uuid, char **bufp)
 /**
  * scan_part() - Scan a kernel partition to see if has a ChromeOS header
  *
- * This reads the first PROBE_SIZE of a partition, loookng for CHROMEOS
+ * This reads the first PROBE_SIZE of a partition, loookng for
+ * VB2_KEYBLOCK_MAGIC
  *
  * @blk: Block device to scan
  * @partnum: Partition number to scan
@@ -114,7 +116,7 @@ static int scan_part(struct udevice *blk, int partnum,
                return log_msg_ret("inf", -EIO);
        }
 
-       if (memcmp("CHROMEOS", hdr, 8)) {
+       if (memcmp(VB2_KEYBLOCK_MAGIC, hdr->magic, VB2_KEYBLOCK_MAGIC_SIZE)) {
                free(hdr);
                return -ENOENT;
        }

diff --git a/boot/bootmeth_cros.h b/boot/bootmeth_cros.h
new file mode 100644 (file)
index 0000000..8e30385
--- /dev/null
+++ b/boot/bootmeth_cros.h
@@ -0,0 +1,197 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Structures used by the ChromiumOS bootmeth
+ *
+ * See docs at:
+ * https://www.chromium.org/chromium-os/chromiumos-design-docs/verified-boot-data-structures/
+ *
+ * Original code at:
+ * https://chromium.googlesource.com/chromiumos/platform/vboot_reference/+/refs/heads/main/firmware/2lib/include/2struct.h
+ *
+ * Code taken from vboot_reference commit 5b8596ce file 2struct.h
+ *
+ * Copyright 2023 Google LLC
+ * Written by Simon Glass <sjg@chromium.org>
+ */
+
+#ifndef __BOOTMETH_CROS_H
+#define __BOOTMETH_CROS_H
+
+/* Signature data (a secure hash, possibly signed) */
+struct vb2_signature {
+       /* Offset of signature data from start of this struct */
+       uint32_t sig_offset;
+       uint32_t reserved0;
+
+       /* Size of signature data in bytes */
+       uint32_t sig_size;
+       uint32_t reserved1;
+
+       /* Size of the data block which was signed in bytes */
+       uint32_t data_size;
+       uint32_t reserved2;
+} __attribute__((packed));
+
+#define EXPECTED_VB2_SIGNATURE_SIZE 24
+
+/* Packed public key data */
+struct vb2_packed_key {
+       /* Offset of key data from start of this struct */
+       uint32_t key_offset;
+       uint32_t reserved0;
+
+       /* Size of key data in bytes (NOT strength of key in bits) */
+       uint32_t key_size;
+       uint32_t reserved1;
+
+       /* Signature algorithm used by the key (enum vb2_crypto_algorithm) */
+       uint32_t algorithm;
+       uint32_t reserved2;
+
+       /* Key version */
+       uint32_t key_version;
+       uint32_t reserved3;
+
+       /* TODO: when redoing this struct, add a text description of the key */
+} __attribute__((packed));
+
+#define EXPECTED_VB2_PACKED_KEY_SIZE 32
+
+#define VB2_KEYBLOCK_MAGIC "CHROMEOS"
+#define VB2_KEYBLOCK_MAGIC_SIZE 8
+
+/*
+ * Keyblock, containing the public key used to sign some other chunk of data.
+ *
+ * This should be followed by:
+ *   1) The data_key key data, pointed to by data_key.key_offset.
+ *   2) The checksum data for (vb2_keyblock + data_key data), pointed to
+ *      by keyblock_checksum.sig_offset.
+ *   3) The signature data for (vb2_keyblock + data_key data), pointed to
+ *      by keyblock_signature.sig_offset.
+ */
+struct vb2_keyblock {
+       /* Magic number */
+       uint8_t magic[VB2_KEYBLOCK_MAGIC_SIZE];
+
+       /* Version of this header format */
+       uint32_t header_version_major;
+       uint32_t header_version_minor;
+
+       /*
+        * Length of this entire keyblock, including keys, signatures, and
+        * padding, in bytes
+        */
+       uint32_t keyblock_size;
+       uint32_t reserved0;
+
+       /*
+        * Signature for this keyblock (header + data pointed to by data_key)
+        * For use with signed data keys
+        */
+       struct vb2_signature keyblock_signature;
+
+       /*
+        * SHA-512 hash for this keyblock (header + data pointed to by
+        * data_key) For use with unsigned data keys.
+        *
+        * Only supported for kernel keyblocks, not firmware keyblocks.
+        */
+       struct vb2_signature keyblock_hash;
+
+       /* Flags for key (VB2_KEYBLOCK_FLAG_*) */
+       uint32_t keyblock_flags;
+       uint32_t reserved1;
+
+       /* Key to verify the chunk of data */
+       struct vb2_packed_key data_key;
+} __attribute__((packed));
+
+#define EXPECTED_VB2_KEYBLOCK_SIZE 112
+
+/*
+ * Preamble block for kernel, version 2.2
+ *
+ * This should be followed by:
+ *   1) The signature data for the kernel body, pointed to by
+ *      body_signature.sig_offset.
+ *   2) The signature data for (vb2_kernel_preamble + body signature data),
+ *       pointed to by preamble_signature.sig_offset.
+ *   3) The 16-bit vmlinuz header, which is used for reconstruction of
+ *      vmlinuz image.
+ */
+struct vb2_kernel_preamble {
+       /*
+        * Size of this preamble, including keys, signatures, vmlinuz header,
+        * and padding, in bytes
+        */
+       uint32_t preamble_size;
+       uint32_t reserved0;
+
+       /* Signature for this preamble (header + body signature) */
+       struct vb2_signature preamble_signature;
+
+       /* Version of this header format */
+       uint32_t header_version_major;
+       uint32_t header_version_minor;
+
+       /* Kernel version */
+       uint32_t kernel_version;
+       uint32_t reserved1;
+
+       /* Load address for kernel body */
+       uint64_t body_load_address;
+       /* TODO (vboot 2.1): we never used that */
+
+       /* Address of bootloader, after body is loaded at body_load_address */
+       uint64_t bootloader_address;
+       /* TODO (vboot 2.1): should be a 32-bit offset */
+
+       /* Size of bootloader in bytes */
+       uint32_t bootloader_size;
+       uint32_t reserved2;
+
+       /* Signature for the kernel body */
+       struct vb2_signature body_signature;
+
+       /*
+        * TODO (vboot 2.1): fields for kernel offset and size.  Right now the
+        * size is implicitly the same as the size of data signed by the body
+        * signature, and the offset is implicitly at the end of the preamble.
+        * But that forces us to pad the preamble to 64KB rather than just
+        * having a tiny preamble and an offset field.
+        */
+
+       /*
+        * Fields added in header version 2.1.  You must verify the header
+        * version before reading these fields!
+        */
+
+       /*
+        * Address of 16-bit header for vmlinuz reassembly.  Readers should
+        * return 0 for header version < 2.1.
+        */
+       uint64_t vmlinuz_header_address;
+
+       /* Size of 16-bit header for vmlinuz in bytes.  Readers should return 0
+          for header version < 2.1 */
+       uint32_t vmlinuz_header_size;
+       uint32_t reserved3;
+
+       /*
+        * Fields added in header version 2.2.  You must verify the header
+        * version before reading these fields!
+        */
+
+       /*
+        * Flags; see VB2_KERNEL_PREAMBLE_*.  Readers should return 0 for
+        * header version < 2.2.  Flags field is currently defined as:
+        * [31:2] - Reserved (for future use)
+        * [1:0]  - Kernel image type (0b00 - CrOS,
+        *                             0b01 - bootimg,
+        *                             0b10 - multiboot)
+        */
+       uint32_t flags;
+} __attribute__((packed));
+
+#endif /* __BOOTMETH_CROS_H */