1 files changed, 213 insertions, 0 deletions
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 58c32b548e5..edebf741fd2 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1,7 +1,12 @@
 // SPDX-License-Identifier: GPL-2.0+
 #include <common.h>
 #include <fs_internal.h>
+#include <uuid.h>
+#include <memalign.h>
+#include "kernel-shared/btrfs_tree.h"
 #include "disk-io.h"
+#include "ctree.h"
+#include "btrfs.h"
 #include "crypto/hash.h"
 
 int btrfs_csum_data(u16 csum_type, const u8 *data, u8 *out, size_t len)
@@ -20,3 +25,211 @@ int btrfs_csum_data(u16 csum_type, const u8 *data, u8 *out, size_t len)
 		return -EINVAL;
 	}
 }
+
+/*
+ * Check if the super is valid:
+ * - nodesize/sectorsize - minimum, maximum, alignment
+ * - tree block starts   - alignment
+ * - number of devices   - something sane
+ * - sys array size      - maximum
+ */
+static int btrfs_check_super(struct btrfs_super_block *sb)
+{
+	u8 result[BTRFS_CSUM_SIZE];
+	u16 csum_type;
+	int csum_size;
+	u8 *metadata_uuid;
+
+	if (btrfs_super_magic(sb) != BTRFS_MAGIC)
+		return -EIO;
+
+	csum_type = btrfs_super_csum_type(sb);
+	if (csum_type >= btrfs_super_num_csums()) {
+		error("unsupported checksum algorithm %u", csum_type);
+		return -EIO;
+	}
+	csum_size = btrfs_super_csum_size(sb);
+
+	btrfs_csum_data(csum_type, (u8 *)sb + BTRFS_CSUM_SIZE,
+			result, BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE);
+
+	if (memcmp(result, sb->csum, csum_size)) {
+		error("superblock checksum mismatch");
+		return -EIO;
+	}
+	if (btrfs_super_root_level(sb) >= BTRFS_MAX_LEVEL) {
+		error("tree_root level too big: %d >= %d",
+			btrfs_super_root_level(sb), BTRFS_MAX_LEVEL);
+		goto error_out;
+	}
+	if (btrfs_super_chunk_root_level(sb) >= BTRFS_MAX_LEVEL) {
+		error("chunk_root level too big: %d >= %d",
+			btrfs_super_chunk_root_level(sb), BTRFS_MAX_LEVEL);
+		goto error_out;
+	}
+	if (btrfs_super_log_root_level(sb) >= BTRFS_MAX_LEVEL) {
+		error("log_root level too big: %d >= %d",
+			btrfs_super_log_root_level(sb), BTRFS_MAX_LEVEL);
+		goto error_out;
+	}
+
+	if (!IS_ALIGNED(btrfs_super_root(sb), 4096)) {
+		error("tree_root block unaligned: %llu", btrfs_super_root(sb));
+		goto error_out;
+	}
+	if (!IS_ALIGNED(btrfs_super_chunk_root(sb), 4096)) {
+		error("chunk_root block unaligned: %llu",
+			btrfs_super_chunk_root(sb));
+		goto error_out;
+	}
+	if (!IS_ALIGNED(btrfs_super_log_root(sb), 4096)) {
+		error("log_root block unaligned: %llu",
+			btrfs_super_log_root(sb));
+		goto error_out;
+	}
+	if (btrfs_super_nodesize(sb) < 4096) {
+		error("nodesize too small: %u < 4096",
+			btrfs_super_nodesize(sb));
+		goto error_out;
+	}
+	if (!IS_ALIGNED(btrfs_super_nodesize(sb), 4096)) {
+		error("nodesize unaligned: %u", btrfs_super_nodesize(sb));
+		goto error_out;
+	}
+	if (btrfs_super_sectorsize(sb) < 4096) {
+		error("sectorsize too small: %u < 4096",
+			btrfs_super_sectorsize(sb));
+		goto error_out;
+	}
+	if (!IS_ALIGNED(btrfs_super_sectorsize(sb), 4096)) {
+		error("sectorsize unaligned: %u", btrfs_super_sectorsize(sb));
+		goto error_out;
+	}
+	if (btrfs_super_total_bytes(sb) == 0) {
+		error("invalid total_bytes 0");
+		goto error_out;
+	}
+	if (btrfs_super_bytes_used(sb) < 6 * btrfs_super_nodesize(sb)) {
+		error("invalid bytes_used %llu", btrfs_super_bytes_used(sb));
+		goto error_out;
+	}
+	if ((btrfs_super_stripesize(sb) != 4096)
+		&& (btrfs_super_stripesize(sb) != btrfs_super_sectorsize(sb))) {
+		error("invalid stripesize %u", btrfs_super_stripesize(sb));
+		goto error_out;
+	}
+
+	if (btrfs_super_incompat_flags(sb) & BTRFS_FEATURE_INCOMPAT_METADATA_UUID)
+		metadata_uuid = sb->metadata_uuid;
+	else
+		metadata_uuid = sb->fsid;
+
+	if (memcmp(metadata_uuid, sb->dev_item.fsid, BTRFS_FSID_SIZE) != 0) {
+		char fsid[BTRFS_UUID_UNPARSED_SIZE];
+		char dev_fsid[BTRFS_UUID_UNPARSED_SIZE];
+
+		uuid_unparse(sb->metadata_uuid, fsid);
+		uuid_unparse(sb->dev_item.fsid, dev_fsid);
+		error("dev_item UUID does not match fsid: %s != %s",
+			dev_fsid, fsid);
+		goto error_out;
+	}
+
+	/*
+	 * Hint to catch really bogus numbers, bitflips or so
+	 */
+	if (btrfs_super_num_devices(sb) > (1UL << 31)) {
+		error("suspicious number of devices: %llu",
+			btrfs_super_num_devices(sb));
+	}
+
+	if (btrfs_super_num_devices(sb) == 0) {
+		error("number of devices is 0");
+		goto error_out;
+	}
+
+	/*
+	 * Obvious sys_chunk_array corruptions, it must hold at least one key
+	 * and one chunk
+	 */
+	if (btrfs_super_sys_array_size(sb) > BTRFS_SYSTEM_CHUNK_ARRAY_SIZE) {
+		error("system chunk array too big %u > %u",
+		      btrfs_super_sys_array_size(sb),
+		      BTRFS_SYSTEM_CHUNK_ARRAY_SIZE);
+		goto error_out;
+	}
+	if (btrfs_super_sys_array_size(sb) < sizeof(struct btrfs_disk_key)
+			+ sizeof(struct btrfs_chunk)) {
+		error("system chunk array too small %u < %zu",
+		      btrfs_super_sys_array_size(sb),
+		      sizeof(struct btrfs_disk_key) +
+		      sizeof(struct btrfs_chunk));
+		goto error_out;
+	}
+
+	return 0;
+
+error_out:
+	error("superblock checksum matches but it has invalid members");
+	return -EIO;
+}
+
+/*
+ * btrfs_read_dev_super - read a valid primary superblock from a block device
+ * @desc,@part:	file descriptor of the device
+ * @sb:		buffer where the superblock is going to be read in
+ *
+ * Unlike the btrfs-progs/kernel version, here we ony care about the first
+ * super block, thus it's much simpler.
+ */
+int btrfs_read_dev_super(struct blk_desc *desc, struct disk_partition *part,
+			 struct btrfs_super_block *sb)
+{
+	char tmp[BTRFS_SUPER_INFO_SIZE];
+	struct btrfs_super_block *buf = (struct btrfs_super_block *)tmp;
+	int ret;
+
+	ret = __btrfs_devread(desc, part, tmp, BTRFS_SUPER_INFO_SIZE,
+			      BTRFS_SUPER_INFO_OFFSET);
+	if (ret < BTRFS_SUPER_INFO_SIZE)
+		return -EIO;
+
+	if (btrfs_super_bytenr(buf) != BTRFS_SUPER_INFO_OFFSET)
+		return -EIO;
+
+	if (btrfs_check_super(buf))
+		return -EIO;
+
+	memcpy(sb, buf, BTRFS_SUPER_INFO_SIZE);
+	return 0;
+}
+
+int btrfs_read_superblock(void)
+{
+	ALLOC_CACHE_ALIGN_BUFFER(char, raw_sb, BTRFS_SUPER_INFO_SIZE);
+	struct btrfs_super_block *sb = (struct btrfs_super_block *) raw_sb;
+	int ret;
+
+
+	btrfs_info.sb.generation = 0;
+
+	ret = btrfs_read_dev_super(btrfs_blk_desc, btrfs_part_info, sb);
+	if (ret < 0) {
+		pr_debug("%s: No valid BTRFS superblock found!\n", __func__);
+		return ret;
+	}
+	btrfs_super_block_to_cpu(sb);
+	memcpy(&btrfs_info.sb, sb, sizeof(*sb));
+
+	if (btrfs_info.sb.num_devices != 1) {
+		printf("%s: Unsupported number of devices (%lli). This driver "
+		       "only supports filesystem on one device.\n", __func__,
+		       btrfs_info.sb.num_devices);
+		return -1;
+	}
+
+	pr_debug("Chosen superblock with generation = %llu\n",
+	      btrfs_info.sb.generation);
+
+	return 0;
+}