[PATCH 1/2] partitions: use sector size for EFI GPT

[PATCH 1/2] partitions: use sector size for EFI GPT

[Karel Zak]

Currently, kernel uses strictly 512-byte sectors for EFI GPT parsing.
That's wrong.

UEFI standard (version 2.3, May 2009, 5.3.1 GUID Format overview, page
95) defines that LBA is always based on the logical block size. It
means bdev_logical_block_size() (aka BLKSSZGET) for Linux.

This patch removes static sector size from EFI GPT parser.

The problem is reproducible with the latest GNU Parted:

 # modprobe scsi_debug dev_size_mb=50 sector_size=4096

  # ./parted /dev/sdb print
  Model: Linux scsi_debug (scsi)
  Disk /dev/sdb: 52.4MB
  Sector size (logical/physical): 4096B/4096B
  Partition Table: gpt

  Number  Start   End     Size    File system  Name     Flags
   1      24.6kB  3002kB  2978kB               primary
   2      3002kB  6001kB  2998kB               primary
   3      6001kB  9003kB  3002kB               primary

  # blockdev --rereadpt /dev/sdb
  # dmesg | tail -1
   sdb: unknown partition table      <---- !!!

with this patch:

  # blockdev --rereadpt /dev/sdb
  # dmesg | tail -1
   sdb: sdb1 sdb2 sdb3

Signed-off-by: Karel Zak <kzak@redhat.com>
---
 fs/partitions/efi.c |   21 +++++++++++++--------
 1 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/fs/partitions/efi.c b/fs/partitions/efi.c
index 038a602..da3f576 100644
--- a/fs/partitions/efi.c
+++ b/fs/partitions/efi.c
@@ -1,7 +1,9 @@
 /************************************************************
  * EFI GUID Partition Table handling
- * Per Intel EFI Specification v1.02
- * http://developer.intel.com/technology/efi/efi.htm
+ *
+ * http://www.uefi.org/specs/
+ * http://www.intel.com/technology/efi/
+ *
  * efi.[ch] by Matt Domsch <Matt_Domsch@dell.com>
  *   Copyright 2000,2001,2002,2004 Dell Inc.
  *
@@ -141,7 +143,7 @@ last_lba(struct block_device *bdev)
 {
 	if (!bdev || !bdev->bd_inode)
 		return 0;
-	return (bdev->bd_inode->i_size >> 9) - 1ULL;
+	return (bdev->bd_inode->i_size / bdev_logical_block_size(bdev)) - 1ULL;
 }
 
 static inline int
@@ -188,6 +190,7 @@ static size_t
 read_lba(struct block_device *bdev, u64 lba, u8 * buffer, size_t count)
 {
 	size_t totalreadcount = 0;
+	sector_t n = lba * (bdev_logical_block_size(bdev) / 512);
 
 	if (!bdev || !buffer || lba > last_lba(bdev))
                 return 0;
@@ -195,7 +198,7 @@ read_lba(struct block_device *bdev, u64 lba, u8 * buffer, size_t count)
 	while (count) {
 		int copied = 512;
 		Sector sect;
-		unsigned char *data = read_dev_sector(bdev, lba++, &sect);
+		unsigned char *data = read_dev_sector(bdev, n++, &sect);
 		if (!data)
 			break;
 		if (copied > count)
@@ -601,6 +604,7 @@ efi_partition(struct parsed_partitions *state, struct block_device *bdev)
 	gpt_header *gpt = NULL;
 	gpt_entry *ptes = NULL;
 	u32 i;
+	unsigned ssz = bdev_logical_block_size(bdev) / 512;
 
 	if (!find_valid_gpt(bdev, &gpt, &ptes) || !gpt || !ptes) {
 		kfree(gpt);
@@ -611,13 +615,14 @@ efi_partition(struct parsed_partitions *state, struct block_device *bdev)
 	pr_debug("GUID Partition Table is valid!  Yea!\n");
 
 	for (i = 0; i < le32_to_cpu(gpt->num_partition_entries) && i < state->limit-1; i++) {
+		u64 start = le64_to_cpu(ptes[i].starting_lba);
+		u64 size = le64_to_cpu(ptes[i].ending_lba) -
+			   le64_to_cpu(ptes[i].starting_lba) + 1ULL;
+
 		if (!is_pte_valid(&ptes[i], last_lba(bdev)))
 			continue;
 
-		put_partition(state, i+1, le64_to_cpu(ptes[i].starting_lba),
-				 (le64_to_cpu(ptes[i].ending_lba) -
-                                  le64_to_cpu(ptes[i].starting_lba) +
-				  1ULL));
+		put_partition(state, i+1, start * ssz, size * ssz);
 
 		/* If this is a RAID volume, tell md */
 		if (!efi_guidcmp(ptes[i].partition_type_guid,
-- 
1.6.2.5

[PATCH 2/2] partitions: read whole sector with EFI GPT header

[Karel Zak]

The size of EFI GPT header is not static, but whole sector is
allocated for the header. The HeaderSize field must be greater
than 92 (= sizeof(struct gpt_header) and must be less than or
equal to the logical block size.

It means we have to read whole sector with the header, because the
header crc32 checksum is calculated according to HeaderSize.

For more details see UEFI standard (version 2.3, May 2009):
  - 5.3.1 GUID Format overview, page 93
  - Table 13. GUID Partition Table Header, page 96

Signed-off-by: Karel Zak <kzak@redhat.com>
---
 fs/partitions/efi.c |    7 ++++---
 fs/partitions/efi.h |    8 ++++++--
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/fs/partitions/efi.c b/fs/partitions/efi.c
index da3f576..58eca76 100644
--- a/fs/partitions/efi.c
+++ b/fs/partitions/efi.c
@@ -260,15 +260,16 @@ static gpt_header *
 alloc_read_gpt_header(struct block_device *bdev, u64 lba)
 {
 	gpt_header *gpt;
+	unsigned ssz = bdev_logical_block_size(bdev);
+
 	if (!bdev)
 		return NULL;
 
-	gpt = kzalloc(sizeof (gpt_header), GFP_KERNEL);
+	gpt = kzalloc(ssz, GFP_KERNEL);
 	if (!gpt)
 		return NULL;
 
-	if (read_lba(bdev, lba, (u8 *) gpt,
-		     sizeof (gpt_header)) < sizeof (gpt_header)) {
+	if (read_lba(bdev, lba, (u8 *) gpt, ssz) < ssz) {
 		kfree(gpt);
                 gpt=NULL;
 		return NULL;
diff --git a/fs/partitions/efi.h b/fs/partitions/efi.h
index 2cc89d0..6998b58 100644
--- a/fs/partitions/efi.h
+++ b/fs/partitions/efi.h
@@ -37,7 +37,6 @@
 #define EFI_PMBR_OSTYPE_EFI 0xEF
 #define EFI_PMBR_OSTYPE_EFI_GPT 0xEE
 
-#define GPT_BLOCK_SIZE 512
 #define GPT_HEADER_SIGNATURE 0x5452415020494645ULL
 #define GPT_HEADER_REVISION_V1 0x00010000
 #define GPT_PRIMARY_PARTITION_TABLE_LBA 1
@@ -79,7 +78,12 @@ typedef struct _gpt_header {
 	__le32 num_partition_entries;
 	__le32 sizeof_partition_entry;
 	__le32 partition_entry_array_crc32;
-	u8 reserved2[GPT_BLOCK_SIZE - 92];
+
+	/* The rest of the logical block is reserved by UEFI and must be zero.
+	 * EFI standard handles this by:
+	 *
+	 * uint8_t		reserved2[ BlockSize - 92 ];
+	 */
 } __attribute__ ((packed)) gpt_header;
 
 typedef struct _gpt_entry_attributes {
-- 
1.6.2.5

Re: [PATCH 1/2] partitions: use sector size for EFI GPT

[Jens Axboe]

On Mon, Nov 09 2009, Karel Zak wrote:
> Currently, kernel uses strictly 512-byte sectors for EFI GPT parsing.
> That's wrong.
> 
> UEFI standard (version 2.3, May 2009, 5.3.1 GUID Format overview, page
> 95) defines that LBA is always based on the logical block size. It
> means bdev_logical_block_size() (aka BLKSSZGET) for Linux.
> 
> This patch removes static sector size from EFI GPT parser.
> 
> The problem is reproducible with the latest GNU Parted:
> 
>  # modprobe scsi_debug dev_size_mb=50 sector_size=4096
> 
>   # ./parted /dev/sdb print
>   Model: Linux scsi_debug (scsi)
>   Disk /dev/sdb: 52.4MB
>   Sector size (logical/physical): 4096B/4096B
>   Partition Table: gpt
> 
>   Number  Start   End     Size    File system  Name     Flags
>    1      24.6kB  3002kB  2978kB               primary
>    2      3002kB  6001kB  2998kB               primary
>    3      6001kB  9003kB  3002kB               primary
> 
>   # blockdev --rereadpt /dev/sdb
>   # dmesg | tail -1
>    sdb: unknown partition table      <---- !!!
> 
> with this patch:
> 
>   # blockdev --rereadpt /dev/sdb
>   # dmesg | tail -1
>    sdb: sdb1 sdb2 sdb3
> 
> Signed-off-by: Karel Zak <kzak@redhat.com>

I have applied this patch with the division fixup, and 2/2 as well.
Thanks!

-- 
Jens Axboe

[PATCH 2/2] partitions: read whole sector with EFI GPT header

[Karel Zak]

The size of EFI GPT header is not static, but whole sector is
allocated for the header. The HeaderSize field must be greater
than 92 (= sizeof(struct gpt_header) and must be less than or
equal to the logical block size.

It means we have to read whole sector with the header, because the
header crc32 checksum is calculated according to HeaderSize.

For more details see UEFI standard (version 2.3, May 2009):
  - 5.3.1 GUID Format overview, page 93
  - Table 13. GUID Partition Table Header, page 96

Signed-off-by: Karel Zak <kzak@redhat.com>
---
 fs/partitions/efi.c |    7 ++++---
 fs/partitions/efi.h |    8 ++++++--
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/fs/partitions/efi.c b/fs/partitions/efi.c
index da3f576..58eca76 100644
--- a/fs/partitions/efi.c
+++ b/fs/partitions/efi.c
@@ -260,15 +260,16 @@ static gpt_header *
 alloc_read_gpt_header(struct block_device *bdev, u64 lba)
 {
 	gpt_header *gpt;
+	unsigned ssz = bdev_logical_block_size(bdev);
+
 	if (!bdev)
 		return NULL;
 
-	gpt = kzalloc(sizeof (gpt_header), GFP_KERNEL);
+	gpt = kzalloc(ssz, GFP_KERNEL);
 	if (!gpt)
 		return NULL;
 
-	if (read_lba(bdev, lba, (u8 *) gpt,
-		     sizeof (gpt_header)) < sizeof (gpt_header)) {
+	if (read_lba(bdev, lba, (u8 *) gpt, ssz) < ssz) {
 		kfree(gpt);
                 gpt=NULL;
 		return NULL;
diff --git a/fs/partitions/efi.h b/fs/partitions/efi.h
index 2cc89d0..6998b58 100644
--- a/fs/partitions/efi.h
+++ b/fs/partitions/efi.h
@@ -37,7 +37,6 @@
 #define EFI_PMBR_OSTYPE_EFI 0xEF
 #define EFI_PMBR_OSTYPE_EFI_GPT 0xEE
 
-#define GPT_BLOCK_SIZE 512
 #define GPT_HEADER_SIGNATURE 0x5452415020494645ULL
 #define GPT_HEADER_REVISION_V1 0x00010000
 #define GPT_PRIMARY_PARTITION_TABLE_LBA 1
@@ -79,7 +78,12 @@ typedef struct _gpt_header {
 	__le32 num_partition_entries;
 	__le32 sizeof_partition_entry;
 	__le32 partition_entry_array_crc32;
-	u8 reserved2[GPT_BLOCK_SIZE - 92];
+
+	/* The rest of the logical block is reserved by UEFI and must be zero.
+	 * EFI standard handles this by:
+	 *
+	 * uint8_t		reserved2[ BlockSize - 92 ];
+	 */
 } __attribute__ ((packed)) gpt_header;
 
 typedef struct _gpt_entry_attributes {
-- 
1.6.2.5