1 files changed, 104 insertions, 0 deletions
diff --git a/libblkid/src/superblocks/cs_fvault2.c b/libblkid/src/superblocks/cs_fvault2.c
new file mode 100644
index 0000000..ef2b567
--- /dev/null
+++ b/libblkid/src/superblocks/cs_fvault2.c
@@ -0,0 +1,104 @@
+/*
+ * Copyright (C) 2022 Milan Broz <gmazyland@gmail.com>
+ *
+ * This file may be redistributed under the terms of the
+ * GNU Lesser General Public License.
+ */
+
+#include "superblocks.h"
+#include "crc32c.h"
+
+/*
+ * For header details, see:
+ * https://github.com/libyal/libfvde/blob/main/documentation/FileVault%20Drive%20Encryption%20(FVDE).asciidoc
+ * https://is.muni.cz/auth/th/p0aok/thesis.pdf
+ */
+
+/* Apple Core Storage magic bytes */
+#define CS_MAGIC	"CS"
+
+struct crc32_checksum {
+	uint32_t value;
+	uint32_t seed;
+} __attribute__((packed));
+
+/*
+ * The superblock structure describes "physical volume"; Core Storage
+ * then uses another abstractions above, similar to LVM.
+ * After activation through dm-crypt, filesystem (usually HFS+) is on top.
+ * The filesystem block size and used data size cannot be directly derived from
+ * this superblock structure without parsing other metadata blocks.
+ */
+
+struct cs_fvault2_sb {
+	struct crc32_checksum checksum;
+	uint16_t version;
+	uint16_t block_type;
+	uint8_t unknown1[52];
+	uint64_t ph_vol_size;
+	uint8_t unknown2[16];
+	uint16_t magic;
+	uint32_t checksum_algo;
+	uint8_t unknown3[2];
+	uint32_t block_size;
+	uint32_t metadata_size;
+	uint64_t disklbl_blkoff;
+	uint64_t other_md_blkoffs[3];
+	uint8_t unknown4[32];
+	uint32_t key_data_size;
+	uint32_t cipher;
+	uint8_t key_data[16];
+	uint8_t unknown5[112];
+	uint8_t ph_vol_uuid[16];
+	uint8_t unknown6[192];
+} __attribute__((packed));
+
+static int cs_fvault2_verify_csum(blkid_probe pr, const struct cs_fvault2_sb *sb)
+{
+	uint32_t seed = le32_to_cpu(sb->checksum.seed);
+	uint32_t crc = le32_to_cpu(sb->checksum.value);
+	unsigned char *buf = (unsigned char *)sb + sizeof(sb->checksum);
+	size_t buf_size = sizeof(*sb) - sizeof(sb->checksum);
+
+	return blkid_probe_verify_csum(pr, crc32c(seed, buf, buf_size), crc);
+}
+
+static int probe_cs_fvault2(blkid_probe pr, const struct blkid_idmag *mag)
+{
+	struct cs_fvault2_sb *sb;
+
+	sb = blkid_probe_get_sb(pr, mag, struct cs_fvault2_sb);
+	if (!sb)
+		return errno ? -errno : BLKID_PROBE_NONE;
+
+	/* Apple Core storage Physical Volume Header; only type 1 checksum is supported  */
+	if (le16_to_cpu(sb->version) != 1 ||
+	    le32_to_cpu(sb->checksum_algo) != 1)
+		return BLKID_PROBE_NONE;
+
+	if (!cs_fvault2_verify_csum(pr, sb))
+		return BLKID_PROBE_NONE;
+
+	/* We support only block type 0x10 as it should be used for FileVault2 */
+	if (le16_to_cpu(sb->block_type) != 0x10 ||
+	    le32_to_cpu(sb->key_data_size) != 16 ||
+	    le32_to_cpu(sb->cipher) != 2 /* AES-XTS */)
+		return BLKID_PROBE_NONE;
+
+	blkid_probe_sprintf_version(pr, "%u", le16_to_cpu(sb->version));
+	blkid_probe_set_uuid(pr, sb->ph_vol_uuid);
+
+	return BLKID_PROBE_OK;
+}
+
+const struct blkid_idinfo cs_fvault2_idinfo =
+{
+	.name		= "cs_fvault2",
+	.usage		= BLKID_USAGE_CRYPTO,
+	.probefunc	= probe_cs_fvault2,
+	.magics		=
+	{
+		{ .magic = CS_MAGIC, .len = 2, .sboff = 88 },
+		{ NULL }
+	}
+};