1 files changed, 412 insertions, 0 deletions

diff --git a/libblkid/gpt.c b/libblkid/gpt.c
new file mode 100644
index 000000000..7288d683e
--- /dev/null
+++ b/libblkid/gpt.c
@@ -0,0 +1,412 @@
+/*
+ * EFI GPT partition parsing code
+ *
+ * Copyright (C) 2009 Karel Zak <kzak@redhat.com>
+ *
+ * This file may be redistributed under the terms of the
+ * GNU Lesser General Public License.
+ *
+ * This code is not copy & past from any other implementation.
+ *
+ * For more information about GPT start your study at:
+ * http://en.wikipedia.org/wiki/GUID_Partition_Table
+ * http://technet.microsoft.com/en-us/library/cc739412(WS.10).aspx
+ */
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <stddef.h>
+
+#include "partitions.h"
+#include "crc32.h"
+#include "dos.h"
+
+#define GPT_PRIMARY_LBA	1
+
+/* Signature - “EFI PART” */
+#define GPT_HEADER_SIGNATURE 0x5452415020494645ULL
+#define GPT_HEADER_SIGNATURE_STR "EFI PART"
+
+/* basic types */
+typedef uint16_t efi_char16_t;
+
+/* UUID */
+typedef struct {
+	uint32_t time_low;
+	uint16_t time_mid;
+	uint16_t time_hi_and_version;
+	uint8_t clock_seq_hi;
+	uint8_t clock_seq_low;
+	uint8_t node[6];
+} efi_guid_t;
+
+
+#define GPT_UNUSED_ENTRY_GUID \
+	    ((efi_guid_t) { 0x00000000, 0x0000, 0x0000, 0x00, 0x00, \
+	                    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }})
+struct gpt_header {
+	uint64_t	signature;		/* "EFI PART" */
+	uint32_t	revision;
+	uint32_t	header_size;		/* usually 92 bytes */
+	uint32_t	header_crc32;		/* checksum of header with this
+						 * field zeroed during calculation */
+	uint32_t	reserved1;
+
+	uint64_t	my_lba;			/* location of this header copy */
+	uint64_t	alternate_lba;		/* location of the other header copy */
+	uint64_t	first_usable_lba;	/* lirst usable LBA for partitions */
+	uint64_t	last_usable_lba;	/* last usable LBA for partitions */
+
+	efi_guid_t	disk_guid;		/* disk UUID */
+
+	uint64_t	partition_entries_lba;	/* always 2 in primary header copy */
+	uint32_t	num_partition_entries;
+	uint32_t	sizeof_partition_entry;
+	uint32_t	partition_entry_array_crc32;
+
+	/*
+	 * The rest of the block is reserved by UEFI and must be zero. EFI
+	 * standard handles this by:
+	 *
+	 * uint8_t		reserved2[ BLKSSZGET - 92 ];
+	 *
+	 * This definition is useless in practice. It is necessary to read
+	 * whole block from the device rather than sizeof(struct gpt_header)
+	 * only.
+	 */
+} __attribute__ ((packed));
+
+/*** not used
+struct gpt_entry_attributes {
+	uint64_t	required_to_function:1;
+	uint64_t	reserved:47;
+        uint64_t	type_guid_specific:16;
+} __attribute__ ((packed));
+***/
+
+struct gpt_entry {
+	efi_guid_t	partition_type_guid;	/* type UUID */
+	efi_guid_t	unique_partition_guid;	/* partition UUID */
+	uint64_t	starting_lba;
+	uint64_t	ending_lba;
+
+	/*struct gpt_entry_attributes	attributes;*/
+
+	uint64_t	attributes;
+
+	efi_char16_t	partition_name[72 / sizeof(efi_char16_t)]; /* UTF-16LE string*/
+} __attribute__ ((packed));
+
+
+/*
+ * EFI uses crc32 with ~0 seed and xor's with ~0 at the end.
+ */
+static inline uint32_t count_crc32(const unsigned char *buf, size_t len)
+{
+	return (crc32(~0L, buf, len) ^ ~0L);
+}
+
+static inline unsigned char *get_lba_buffer(blkid_probe pr,
+					uint64_t lba, size_t bytes)
+{
+	return blkid_probe_get_buffer(pr,
+			blkid_probe_get_sectorsize(pr) * lba, bytes);
+}
+
+static inline int guidcmp(efi_guid_t left, efi_guid_t right)
+{
+	return memcmp(&left, &right, sizeof (efi_guid_t));
+}
+
+/*
+ * UUID is traditionally 16 byte big-endian array, except Intel EFI
+ * specification where the UUID is a structure of little-endian fields.
+ */
+static void swap_efi_guid(efi_guid_t *uid)
+{
+	uid->time_low = swab32(uid->time_low);
+	uid->time_mid = swab16(uid->time_mid);
+	uid->time_hi_and_version = swab16(uid->time_hi_and_version);
+}
+
+static int last_lba(blkid_probe pr, uint64_t *lba)
+{
+	blkid_loff_t sz = blkid_probe_get_size(pr);
+	unsigned int ssz = blkid_probe_get_sectorsize(pr);
+
+	if (sz < ssz)
+		return -1;
+
+	*lba = (sz / ssz) - 1ULL;
+	return 0;
+}
+
+/*
+ * Protective (legacy) MBR.
+ *
+ * This MBR contains standard DOS partition table with a single partition, type
+ * of 0xEE.  The partition usually encompassing the entire GPT drive - or 2TiB
+ * for large disks.
+ *
+ * Note that Apple uses GPT/MBR hybrid disks, where the DOS partition table is
+ * synchronized with GPT. This synchronization has many restriction of course
+ * (due DOS PT limitations).
+ *
+ * Note that the PMBR detection is optional (enabled by default) and could be
+ * disabled by BLKID_PARTS_FOPCE_GPT flag (see also blkid_paertitions_set_flags()).
+ */
+static int is_pmbr_valid(blkid_probe pr)
+{
+	int flags = blkid_partitions_get_flags(pr);
+	unsigned char *data;
+	struct dos_partition *p;
+	int i;
+
+	if (flags & BLKID_PARTS_FORCE_GPT)
+		goto ok;			/* skip PMBR check */
+
+	data = blkid_probe_get_sector(pr, 0);
+	if (!data)
+		goto failed;
+
+	if (!is_valid_mbr_signature(data))
+		goto failed;
+
+	p = (struct dos_partition *) (data + BLKID_MSDOS_PT_OFFSET);
+
+	for (i = 0; i < 4; i++, p++) {
+		if (p->sys_type == BLKID_GPT_PARTITION)
+			goto ok;
+	}
+failed:
+	return 0;
+ok:
+	return 1;
+}
+
+/*
+ * Reads GPT header to @hdr and returns a pointer to @hdr or NULL in case of
+ * error. The function also returns GPT entries in @ents.
+ *
+ * Note, this function does not allocate any memory. The GPT header has fixed
+ * size so we use stack, and @ents returns memory from libblkid buffer (so the
+ * next blkid_probe_get_buffer() will overwrite this buffer).
+ *
+ * This function checks validity of header and entries array. A corrupted
+ * header is not returned.
+ */
+static struct gpt_header *get_gpt_header(
+				blkid_probe pr, struct gpt_header *hdr,
+				struct gpt_entry **ents, uint64_t lba,
+				uint64_t lastlba)
+{
+	struct gpt_header *h;
+	uint32_t crc, orgcrc;
+	uint64_t lu, fu;
+	size_t esz;
+	uint32_t hsz, ssz;
+
+	ssz = blkid_probe_get_sectorsize(pr);
+
+	/* whole sector is allocated for GPT header */
+	h = (struct gpt_header *) get_lba_buffer(pr, lba, ssz);
+	if (!h)
+		return NULL;
+
+	if (le64_to_cpu(h->signature) != GPT_HEADER_SIGNATURE)
+		return NULL;
+
+	hsz = le32_to_cpu(h->header_size);
+
+	/* EFI: The HeaderSize must be greater than 92 and must be less
+	 *      than or equal to the logical block size.
+	 */
+	if (hsz > ssz || hsz < sizeof(*h))
+		return NULL;
+
+	/* Header has to be verified when header_crc32 is zero */
+	orgcrc = h->header_crc32;
+	h->header_crc32 = 0;
+	crc = count_crc32((unsigned char *) h, hsz);
+	h->header_crc32 = orgcrc;
+
+	if (crc != le32_to_cpu(orgcrc)) {
+		DBG(DEBUG_LOWPROBE, printf("GPT header corrupted\n"));
+		return NULL;
+	}
+
+	/* Valid header has to be at MyLBA */
+	if (le64_to_cpu(h->my_lba) != lba) {
+		DBG(DEBUG_LOWPROBE, printf(
+			"GPT->MyLBA mismatch with real position\n"));
+		return NULL;
+	}
+
+	fu = le64_to_cpu(h->first_usable_lba);
+	lu = le64_to_cpu(h->last_usable_lba);
+
+	/* Check if First and Last usable LBA makes sense */
+	if (lu < fu || fu > lastlba || lu > lastlba) {
+		DBG(DEBUG_LOWPROBE, printf(
+			"GPT->{First,Last}UsableLBA out of range\n"));
+		return NULL;
+	}
+
+	/* The header has to be outside usable range */
+	if (fu < lba && lba < lu) {
+		DBG(DEBUG_LOWPROBE, printf("GPT header is inside usable area\n"));
+		return NULL;
+	}
+
+	/* Size of blocks with GPT entries */
+	esz = le32_to_cpu(h->num_partition_entries) *
+			le32_to_cpu(h->sizeof_partition_entry);
+	if (!esz) {
+		DBG(DEBUG_LOWPROBE, printf("GPT entries undefined\n"));
+		return NULL;
+	}
+
+	/* The header seems valid, save it
+	 * (we don't care about zeros in hdr->reserved2 area) */
+	memcpy(hdr, h, sizeof(*h));
+	h = hdr;
+
+	/* Read GPT entries */
+	*ents = (struct gpt_entry *) get_lba_buffer(pr,
+				le64_to_cpu(h->partition_entries_lba), esz);
+	if (!*ents) {
+		DBG(DEBUG_LOWPROBE, printf("GPT entries unreadable\n"));
+		return NULL;
+	}
+
+	/* Validate entries */
+	crc = count_crc32((unsigned char *) *ents, esz);
+	if (crc != le32_to_cpu(h->partition_entry_array_crc32)) {
+		DBG(DEBUG_LOWPROBE, printf("GPT entries corrupted\n"));
+		return NULL;
+	}
+
+	return h;
+}
+
+static int probe_gpt_pt(blkid_probe pr,
+		const struct blkid_idmag *mag __attribute__((__unused__)))
+{
+	uint64_t lastlba = 0, lba;
+	struct gpt_header hdr, *h;
+	struct gpt_entry *e;
+	blkid_parttable tab = NULL;
+	blkid_partlist ls;
+	uint64_t fu, lu;
+	uint32_t ssf, i;
+	efi_guid_t guid;
+
+	if (last_lba(pr, &lastlba))
+		goto nothing;
+
+	if (!is_pmbr_valid(pr))
+		goto nothing;
+
+	h = get_gpt_header(pr, &hdr, &e, (lba = GPT_PRIMARY_LBA), lastlba);
+	if (!h)
+		h = get_gpt_header(pr, &hdr, &e, (lba = lastlba), lastlba);
+
+	if (!h)
+		goto nothing;
+
+	blkid_probe_use_wiper(pr, lba * blkid_probe_get_size(pr), 8);
+
+	if (blkid_probe_set_magic(pr, lba << 9,
+			      sizeof(GPT_HEADER_SIGNATURE_STR) - 1,
+			      (unsigned char *) GPT_HEADER_SIGNATURE_STR))
+		goto err;
+
+	if (blkid_partitions_need_typeonly(pr))
+		/* caller does not ask for details about partitions */
+		return 0;
+
+	ls = blkid_probe_get_partlist(pr);
+	if (!ls)
+		goto err;
+
+	tab = blkid_partlist_new_parttable(ls, "gpt", lba << 9);
+	if (!tab)
+		goto err;
+
+	guid = h->disk_guid;
+	swap_efi_guid(&guid);
+	blkid_parttable_set_id(tab, (const unsigned char *) &guid);
+
+	ssf = blkid_probe_get_sectorsize(pr) / 512;
+
+	fu = le64_to_cpu(h->first_usable_lba);
+	lu = le64_to_cpu(h->last_usable_lba);
+
+	for (i = 0; i < le32_to_cpu(h->num_partition_entries); i++, e++) {
+
+		blkid_partition par;
+		uint64_t start = le64_to_cpu(e->starting_lba);
+		uint64_t size = le64_to_cpu(e->ending_lba) -
+					le64_to_cpu(e->starting_lba) + 1ULL;
+
+		/* 00000000-0000-0000-0000-000000000000 entry */
+		if (!guidcmp(e->partition_type_guid, GPT_UNUSED_ENTRY_GUID)) {
+			blkid_partlist_increment_partno(ls);
+			continue;
+		}
+		/* the partition has to inside usable range */
+		if (start < fu || start + size - 1 > lu) {
+			DBG(DEBUG_LOWPROBE, printf(
+				"GPT entry[%d] overflows usable area - ignore\n",
+				i));
+			blkid_partlist_increment_partno(ls);
+			continue;
+		}
+
+		par = blkid_partlist_add_partition(ls, tab,
+					start * ssf, size * ssf);
+		if (!par)
+			goto err;
+
+		blkid_partition_set_utf8name(par,
+			(unsigned char *) e->partition_name,
+			sizeof(e->partition_name), BLKID_ENC_UTF16LE);
+
+		guid = e->unique_partition_guid;
+		swap_efi_guid(&guid);
+		blkid_partition_set_uuid(par, (const unsigned char *) &guid);
+
+		guid = e->partition_type_guid;
+		swap_efi_guid(&guid);
+		blkid_partition_set_type_uuid(par, (const unsigned char *) &guid);
+
+		blkid_partition_set_flags(par, e->attributes);
+	}
+
+	return 0;
+
+nothing:
+	return 1;
+err:
+	return -1;
+}
+
+
+const struct blkid_idinfo gpt_pt_idinfo =
+{
+	.name		= "gpt",
+	.probefunc	= probe_gpt_pt,
+	.minsz		= 1024 * 1440 + 1,	/* ignore floppies */
+
+	/*
+	 * It would be possible to check for DOS signature (0xAA55), but
+	 * unfortunately almost all EFI GPT implemenations allow to optionaly
+	 * skip the legacy MBR. We follows this behavior and MBR is optional.
+	 * See is_valid_pmbr().
+	 *
+	 * It means we have to always call probe_gpt_pt().
+	 */
+	.magics		= BLKID_NONE_MAGIC
+};
+