ANDROID: dm: Add android verity target
This device-mapper target is virtually a VERITY target. This
target is setup by reading the metadata contents piggybacked
to the actual data blocks in the block device. The signature
of the metadata contents are verified against the key included
in the system keyring. Upon success, the underlying verity
target is setup.
BUG: 27175947
Change-Id: I7e99644a0960ac8279f02c0158ed20999510ea97
Signed-off-by: Badhri Jagan Sridharan <Badhri@google.com>
diff --git a/drivers/md/dm-android-verity.h b/drivers/md/dm-android-verity.h
new file mode 100644
index 0000000..11477ff
--- /dev/null
+++ b/drivers/md/dm-android-verity.h
@@ -0,0 +1,92 @@
+/*
+ * Copyright (C) 2015 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef DM_ANDROID_VERITY_H
+#define DM_ANDROID_VERITY_H
+
+#include <crypto/sha.h>
+
+#define RSANUMBYTES 256
+#define VERITY_METADATA_MAGIC_NUMBER 0xb001b001
+#define VERITY_METADATA_MAGIC_DISABLE 0x46464f56
+#define VERITY_METADATA_VERSION 0
+#define VERITY_STATE_DISABLE 1
+#define DATA_BLOCK_SIZE (4 * 1024)
+#define VERITY_METADATA_SIZE (8 * DATA_BLOCK_SIZE)
+#define VERITY_TABLE_ARGS 10
+#define VERITY_COMMANDLINE_PARAM_LENGTH 20
+
+#define FEC_MAGIC 0xFECFECFE
+#define FEC_BLOCK_SIZE (4 * 1024)
+#define FEC_VERSION 0
+#define FEC_RSM 255
+#define FEC_ARG_LENGTH 300
+
+#define VERITY_TABLE_OPT_RESTART "restart_on_corruption"
+#define VERITY_TABLE_OPT_LOGGING "ignore_corruption"
+#define VERITY_TABLE_OPT_IGNZERO "ignore_zero_blocks"
+
+#define VERITY_TABLE_OPT_FEC_FORMAT \
+ "use_fec_from_device %s fec_start %llu fec_blocks %llu fec_roots %u ignore_zero_blocks"
+#define VERITY_TABLE_OPT_FEC_ARGS 9
+
+#define VERITY_DEBUG 0
+
+#define DM_MSG_PREFIX "android-verity"
+/*
+ * There can be two formats.
+ * if fec is present
+ * <data_blocks> <verity_tree> <verity_metdata_32K><fec_data><fec_data_4K>
+ * if fec is not present
+ * <data_blocks> <verity_tree> <verity_metdata_32K>
+ */
+/* TODO: rearrange structure to reduce memory holes
+ * depends on userspace change.
+ */
+struct fec_header {
+ __le32 magic;
+ __le32 version;
+ __le32 size;
+ __le32 roots;
+ __le32 fec_size;
+ __le64 inp_size;
+ u8 hash[SHA256_DIGEST_SIZE];
+};
+
+struct android_metadata_header {
+ __le32 magic_number;
+ __le32 protocol_version;
+ char signature[RSANUMBYTES];
+ __le32 table_length;
+};
+
+struct android_metadata {
+ struct android_metadata_header *header;
+ char *verity_table;
+};
+
+struct fec_ecc_metadata {
+ bool valid;
+ u32 roots;
+ u64 blocks;
+ u64 rounds;
+ u64 start;
+};
+
+struct bio_read {
+ struct page **page_io;
+ int number_of_pages;
+};
+
+#endif /* DM_ANDROID_VERITY_H */