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aha/fs/partitions/efi.c
Karel Zak 87038c2d5b partitions: read whole sector with EFI GPT header 
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>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2009-11-23 09:29:58 +01:00

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/************************************************************
* EFI GUID Partition Table handling
*
* 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.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*
* TODO:
*
* Changelog:
* Mon Nov 09 2004 Matt Domsch <Matt_Domsch@dell.com>
* - test for valid PMBR and valid PGPT before ever reading
* AGPT, allow override with 'gpt' kernel command line option.
* - check for first/last_usable_lba outside of size of disk
*
* Tue Mar 26 2002 Matt Domsch <Matt_Domsch@dell.com>
* - Ported to 2.5.7-pre1 and 2.5.7-dj2
* - Applied patch to avoid fault in alternate header handling
* - cleaned up find_valid_gpt
* - On-disk structure and copy in memory is *always* LE now -
* swab fields as needed
* - remove print_gpt_header()
* - only use first max_p partition entries, to keep the kernel minor number
* and partition numbers tied.
*
* Mon Feb 04 2002 Matt Domsch <Matt_Domsch@dell.com>
* - Removed __PRIPTR_PREFIX - not being used
*
* Mon Jan 14 2002 Matt Domsch <Matt_Domsch@dell.com>
* - Ported to 2.5.2-pre11 + library crc32 patch Linus applied
*
* Thu Dec 6 2001 Matt Domsch <Matt_Domsch@dell.com>
* - Added compare_gpts().
* - moved le_efi_guid_to_cpus() back into this file. GPT is the only
* thing that keeps EFI GUIDs on disk.
* - Changed gpt structure names and members to be simpler and more Linux-like.
*
* Wed Oct 17 2001 Matt Domsch <Matt_Domsch@dell.com>
* - Removed CONFIG_DEVFS_VOLUMES_UUID code entirely per Martin Wilck
*
* Wed Oct 10 2001 Matt Domsch <Matt_Domsch@dell.com>
* - Changed function comments to DocBook style per Andreas Dilger suggestion.
*
* Mon Oct 08 2001 Matt Domsch <Matt_Domsch@dell.com>
* - Change read_lba() to use the page cache per Al Viro's work.
* - print u64s properly on all architectures
* - fixed debug_printk(), now Dprintk()
*
* Mon Oct 01 2001 Matt Domsch <Matt_Domsch@dell.com>
* - Style cleanups
* - made most functions static
* - Endianness addition
* - remove test for second alternate header, as it's not per spec,
* and is unnecessary. There's now a method to read/write the last
* sector of an odd-sized disk from user space. No tools have ever
* been released which used this code, so it's effectively dead.
* - Per Asit Mallick of Intel, added a test for a valid PMBR.
* - Added kernel command line option 'gpt' to override valid PMBR test.
*
* Wed Jun 6 2001 Martin Wilck <Martin.Wilck@Fujitsu-Siemens.com>
* - added devfs volume UUID support (/dev/volumes/uuids) for
* mounting file systems by the partition GUID.
*
* Tue Dec 5 2000 Matt Domsch <Matt_Domsch@dell.com>
* - Moved crc32() to linux/lib, added efi_crc32().
*
* Thu Nov 30 2000 Matt Domsch <Matt_Domsch@dell.com>
* - Replaced Intel's CRC32 function with an equivalent
* non-license-restricted version.
*
* Wed Oct 25 2000 Matt Domsch <Matt_Domsch@dell.com>
* - Fixed the last_lba() call to return the proper last block
*
* Thu Oct 12 2000 Matt Domsch <Matt_Domsch@dell.com>
* - Thanks to Andries Brouwer for his debugging assistance.
* - Code works, detects all the partitions.
*
************************************************************/
#include <linux/crc32.h>
#include <linux/math64.h>
#include "check.h"
#include "efi.h"
/* This allows a kernel command line option 'gpt' to override
* the test for invalid PMBR. Not __initdata because reloading
* the partition tables happens after init too.
*/
static int force_gpt;
static int __init
force_gpt_fn(char *str)
{
force_gpt = 1;
return 1;
}
__setup("gpt", force_gpt_fn);
/**
* efi_crc32() - EFI version of crc32 function
* @buf: buffer to calculate crc32 of
* @len - length of buf
*
* Description: Returns EFI-style CRC32 value for @buf
*
* This function uses the little endian Ethernet polynomial
* but seeds the function with ~0, and xor's with ~0 at the end.
* Note, the EFI Specification, v1.02, has a reference to
* Dr. Dobbs Journal, May 1994 (actually it's in May 1992).
*/
static inline u32
efi_crc32(const void *buf, unsigned long len)
{
return (crc32(~0L, buf, len) ^ ~0L);
}
/**
* last_lba(): return number of last logical block of device
* @bdev: block device
*
* Description: Returns last LBA value on success, 0 on error.
* This is stored (by sd and ide-geometry) in
* the part[0] entry for this disk, and is the number of
* physical sectors available on the disk.
*/
static u64
last_lba(struct block_device *bdev)
{
if (!bdev || !bdev->bd_inode)
return 0;
return div_u64(bdev->bd_inode->i_size,
bdev_logical_block_size(bdev)) - 1ULL;
}
static inline int
pmbr_part_valid(struct partition *part)
{
if (part->sys_ind == EFI_PMBR_OSTYPE_EFI_GPT &&
le32_to_cpu(part->start_sect) == 1UL)
return 1;
return 0;
}
/**
* is_pmbr_valid(): test Protective MBR for validity
* @mbr: pointer to a legacy mbr structure
*
* Description: Returns 1 if PMBR is valid, 0 otherwise.
* Validity depends on two things:
* 1) MSDOS signature is in the last two bytes of the MBR
* 2) One partition of type 0xEE is found
*/
static int
is_pmbr_valid(legacy_mbr *mbr)
{
int i;
if (!mbr || le16_to_cpu(mbr->signature) != MSDOS_MBR_SIGNATURE)
return 0;
for (i = 0; i < 4; i++)
if (pmbr_part_valid(&mbr->partition_record[i]))
return 1;
return 0;
}
/**
* read_lba(): Read bytes from disk, starting at given LBA
* @bdev
* @lba
* @buffer
* @size_t
*
* Description: Reads @count bytes from @bdev into @buffer.
* Returns number of bytes read on success, 0 on error.
*/
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;
while (count) {
int copied = 512;
Sector sect;
unsigned char *data = read_dev_sector(bdev, n++, &sect);
if (!data)
break;
if (copied > count)
copied = count;
memcpy(buffer, data, copied);
put_dev_sector(sect);
buffer += copied;
totalreadcount +=copied;
count -= copied;
}
return totalreadcount;
}
/**
* alloc_read_gpt_entries(): reads partition entries from disk
* @bdev
* @gpt - GPT header
*
* Description: Returns ptes on success, NULL on error.
* Allocates space for PTEs based on information found in @gpt.
* Notes: remember to free pte when you're done!
*/
static gpt_entry *
alloc_read_gpt_entries(struct block_device *bdev, gpt_header *gpt)
{
size_t count;
gpt_entry *pte;
if (!bdev || !gpt)
return NULL;
count = le32_to_cpu(gpt->num_partition_entries) *
le32_to_cpu(gpt->sizeof_partition_entry);
if (!count)
return NULL;
pte = kzalloc(count, GFP_KERNEL);
if (!pte)
return NULL;
if (read_lba(bdev, le64_to_cpu(gpt->partition_entry_lba),
(u8 *) pte,
count) < count) {
kfree(pte);
pte=NULL;
return NULL;
}
return pte;
}
/**
* alloc_read_gpt_header(): Allocates GPT header, reads into it from disk
* @bdev
* @lba is the Logical Block Address of the partition table
*
* Description: returns GPT header on success, NULL on error. Allocates
* and fills a GPT header starting at @ from @bdev.
* Note: remember to free gpt when finished with it.
*/
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(ssz, GFP_KERNEL);
if (!gpt)
return NULL;
if (read_lba(bdev, lba, (u8 *) gpt, ssz) < ssz) {
kfree(gpt);
gpt=NULL;
return NULL;
}
return gpt;
}
/**
* is_gpt_valid() - tests one GPT header and PTEs for validity
* @bdev
* @lba is the logical block address of the GPT header to test
* @gpt is a GPT header ptr, filled on return.
* @ptes is a PTEs ptr, filled on return.
*
* Description: returns 1 if valid, 0 on error.
* If valid, returns pointers to newly allocated GPT header and PTEs.
*/
static int
is_gpt_valid(struct block_device *bdev, u64 lba,
gpt_header **gpt, gpt_entry **ptes)
{
u32 crc, origcrc;
u64 lastlba;
if (!bdev || !gpt || !ptes)
return 0;
if (!(*gpt = alloc_read_gpt_header(bdev, lba)))
return 0;
/* Check the GUID Partition Table signature */
if (le64_to_cpu((*gpt)->signature) != GPT_HEADER_SIGNATURE) {
pr_debug("GUID Partition Table Header signature is wrong:"
"%lld != %lld\n",
(unsigned long long)le64_to_cpu((*gpt)->signature),
(unsigned long long)GPT_HEADER_SIGNATURE);
goto fail;
}
/* Check the GUID Partition Table CRC */
origcrc = le32_to_cpu((*gpt)->header_crc32);
(*gpt)->header_crc32 = 0;
crc = efi_crc32((const unsigned char *) (*gpt), le32_to_cpu((*gpt)->header_size));
if (crc != origcrc) {
pr_debug("GUID Partition Table Header CRC is wrong: %x != %x\n",
crc, origcrc);
goto fail;
}
(*gpt)->header_crc32 = cpu_to_le32(origcrc);
/* Check that the my_lba entry points to the LBA that contains
* the GUID Partition Table */
if (le64_to_cpu((*gpt)->my_lba) != lba) {
pr_debug("GPT my_lba incorrect: %lld != %lld\n",
(unsigned long long)le64_to_cpu((*gpt)->my_lba),
(unsigned long long)lba);
goto fail;
}
/* Check the first_usable_lba and last_usable_lba are
* within the disk.
*/
lastlba = last_lba(bdev);
if (le64_to_cpu((*gpt)->first_usable_lba) > lastlba) {
pr_debug("GPT: first_usable_lba incorrect: %lld > %lld\n",
(unsigned long long)le64_to_cpu((*gpt)->first_usable_lba),
(unsigned long long)lastlba);
goto fail;
}
if (le64_to_cpu((*gpt)->last_usable_lba) > lastlba) {
pr_debug("GPT: last_usable_lba incorrect: %lld > %lld\n",
(unsigned long long)le64_to_cpu((*gpt)->last_usable_lba),
(unsigned long long)lastlba);
goto fail;
}
if (!(*ptes = alloc_read_gpt_entries(bdev, *gpt)))
goto fail;
/* Check the GUID Partition Entry Array CRC */
crc = efi_crc32((const unsigned char *) (*ptes),
le32_to_cpu((*gpt)->num_partition_entries) *
le32_to_cpu((*gpt)->sizeof_partition_entry));
if (crc != le32_to_cpu((*gpt)->partition_entry_array_crc32)) {
pr_debug("GUID Partitition Entry Array CRC check failed.\n");
goto fail_ptes;
}
/* We're done, all's well */
return 1;
fail_ptes:
kfree(*ptes);
*ptes = NULL;
fail:
kfree(*gpt);
*gpt = NULL;
return 0;
}
/**
* is_pte_valid() - tests one PTE for validity
* @pte is the pte to check
* @lastlba is last lba of the disk
*
* Description: returns 1 if valid, 0 on error.
*/
static inline int
is_pte_valid(const gpt_entry *pte, const u64 lastlba)
{
if ((!efi_guidcmp(pte->partition_type_guid, NULL_GUID)) ||
le64_to_cpu(pte->starting_lba) > lastlba ||
le64_to_cpu(pte->ending_lba) > lastlba)
return 0;
return 1;
}
/**
* compare_gpts() - Search disk for valid GPT headers and PTEs
* @pgpt is the primary GPT header
* @agpt is the alternate GPT header
* @lastlba is the last LBA number
* Description: Returns nothing. Sanity checks pgpt and agpt fields
* and prints warnings on discrepancies.
*
*/
static void
compare_gpts(gpt_header *pgpt, gpt_header *agpt, u64 lastlba)
{
int error_found = 0;
if (!pgpt || !agpt)
return;
if (le64_to_cpu(pgpt->my_lba) != le64_to_cpu(agpt->alternate_lba)) {
printk(KERN_WARNING
"GPT:Primary header LBA != Alt. header alternate_lba\n");
printk(KERN_WARNING "GPT:%lld != %lld\n",
(unsigned long long)le64_to_cpu(pgpt->my_lba),
(unsigned long long)le64_to_cpu(agpt->alternate_lba));
error_found++;
}
if (le64_to_cpu(pgpt->alternate_lba) != le64_to_cpu(agpt->my_lba)) {
printk(KERN_WARNING
"GPT:Primary header alternate_lba != Alt. header my_lba\n");
printk(KERN_WARNING "GPT:%lld != %lld\n",
(unsigned long long)le64_to_cpu(pgpt->alternate_lba),
(unsigned long long)le64_to_cpu(agpt->my_lba));
error_found++;
}
if (le64_to_cpu(pgpt->first_usable_lba) !=
le64_to_cpu(agpt->first_usable_lba)) {
printk(KERN_WARNING "GPT:first_usable_lbas don't match.\n");
printk(KERN_WARNING "GPT:%lld != %lld\n",
(unsigned long long)le64_to_cpu(pgpt->first_usable_lba),
(unsigned long long)le64_to_cpu(agpt->first_usable_lba));
error_found++;
}
if (le64_to_cpu(pgpt->last_usable_lba) !=
le64_to_cpu(agpt->last_usable_lba)) {
printk(KERN_WARNING "GPT:last_usable_lbas don't match.\n");
printk(KERN_WARNING "GPT:%lld != %lld\n",
(unsigned long long)le64_to_cpu(pgpt->last_usable_lba),
(unsigned long long)le64_to_cpu(agpt->last_usable_lba));
error_found++;
}
if (efi_guidcmp(pgpt->disk_guid, agpt->disk_guid)) {
printk(KERN_WARNING "GPT:disk_guids don't match.\n");
error_found++;
}
if (le32_to_cpu(pgpt->num_partition_entries) !=
le32_to_cpu(agpt->num_partition_entries)) {
printk(KERN_WARNING "GPT:num_partition_entries don't match: "
"0x%x != 0x%x\n",
le32_to_cpu(pgpt->num_partition_entries),
le32_to_cpu(agpt->num_partition_entries));
error_found++;
}
if (le32_to_cpu(pgpt->sizeof_partition_entry) !=
le32_to_cpu(agpt->sizeof_partition_entry)) {
printk(KERN_WARNING
"GPT:sizeof_partition_entry values don't match: "
"0x%x != 0x%x\n",
le32_to_cpu(pgpt->sizeof_partition_entry),
le32_to_cpu(agpt->sizeof_partition_entry));
error_found++;
}
if (le32_to_cpu(pgpt->partition_entry_array_crc32) !=
le32_to_cpu(agpt->partition_entry_array_crc32)) {
printk(KERN_WARNING
"GPT:partition_entry_array_crc32 values don't match: "
"0x%x != 0x%x\n",
le32_to_cpu(pgpt->partition_entry_array_crc32),
le32_to_cpu(agpt->partition_entry_array_crc32));
error_found++;
}
if (le64_to_cpu(pgpt->alternate_lba) != lastlba) {
printk(KERN_WARNING
"GPT:Primary header thinks Alt. header is not at the end of the disk.\n");
printk(KERN_WARNING "GPT:%lld != %lld\n",
(unsigned long long)le64_to_cpu(pgpt->alternate_lba),
(unsigned long long)lastlba);
error_found++;
}
if (le64_to_cpu(agpt->my_lba) != lastlba) {
printk(KERN_WARNING
"GPT:Alternate GPT header not at the end of the disk.\n");
printk(KERN_WARNING "GPT:%lld != %lld\n",
(unsigned long long)le64_to_cpu(agpt->my_lba),
(unsigned long long)lastlba);
error_found++;
}
if (error_found)
printk(KERN_WARNING
"GPT: Use GNU Parted to correct GPT errors.\n");
return;
}
/**
* find_valid_gpt() - Search disk for valid GPT headers and PTEs
* @bdev
* @gpt is a GPT header ptr, filled on return.
* @ptes is a PTEs ptr, filled on return.
* Description: Returns 1 if valid, 0 on error.
* If valid, returns pointers to newly allocated GPT header and PTEs.
* Validity depends on PMBR being valid (or being overridden by the
* 'gpt' kernel command line option) and finding either the Primary
* GPT header and PTEs valid, or the Alternate GPT header and PTEs
* valid. If the Primary GPT header is not valid, the Alternate GPT header
* is not checked unless the 'gpt' kernel command line option is passed.
* This protects against devices which misreport their size, and forces
* the user to decide to use the Alternate GPT.
*/
static int
find_valid_gpt(struct block_device *bdev, gpt_header **gpt, gpt_entry **ptes)
{
int good_pgpt = 0, good_agpt = 0, good_pmbr = 0;
gpt_header *pgpt = NULL, *agpt = NULL;
gpt_entry *pptes = NULL, *aptes = NULL;
legacy_mbr *legacymbr;
u64 lastlba;
if (!bdev || !gpt || !ptes)
return 0;
lastlba = last_lba(bdev);
if (!force_gpt) {
/* This will be added to the EFI Spec. per Intel after v1.02. */
legacymbr = kzalloc(sizeof (*legacymbr), GFP_KERNEL);
if (legacymbr) {
read_lba(bdev, 0, (u8 *) legacymbr,
sizeof (*legacymbr));
good_pmbr = is_pmbr_valid(legacymbr);
kfree(legacymbr);
}
if (!good_pmbr)
goto fail;
}
good_pgpt = is_gpt_valid(bdev, GPT_PRIMARY_PARTITION_TABLE_LBA,
&pgpt, &pptes);
if (good_pgpt)
good_agpt = is_gpt_valid(bdev,
le64_to_cpu(pgpt->alternate_lba),
&agpt, &aptes);
if (!good_agpt && force_gpt)
good_agpt = is_gpt_valid(bdev, lastlba,
&agpt, &aptes);
/* The obviously unsuccessful case */
if (!good_pgpt && !good_agpt)
goto fail;
compare_gpts(pgpt, agpt, lastlba);
/* The good cases */
if (good_pgpt) {
*gpt = pgpt;
*ptes = pptes;
kfree(agpt);
kfree(aptes);
if (!good_agpt) {
printk(KERN_WARNING
"Alternate GPT is invalid, "
"using primary GPT.\n");
}
return 1;
}
else if (good_agpt) {
*gpt = agpt;
*ptes = aptes;
kfree(pgpt);
kfree(pptes);
printk(KERN_WARNING
"Primary GPT is invalid, using alternate GPT.\n");
return 1;
}
fail:
kfree(pgpt);
kfree(agpt);
kfree(pptes);
kfree(aptes);
*gpt = NULL;
*ptes = NULL;
return 0;
}
/**
* efi_partition(struct parsed_partitions *state, struct block_device *bdev)
* @state
* @bdev
*
* Description: called from check.c, if the disk contains GPT
* partitions, sets up partition entries in the kernel.
*
* If the first block on the disk is a legacy MBR,
* it will get handled by msdos_partition().
* If it's a Protective MBR, we'll handle it here.
*
* We do not create a Linux partition for GPT, but
* only for the actual data partitions.
* Returns:
* -1 if unable to read the partition table
* 0 if this isn't our partition table
* 1 if successful
*
*/
int
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);
kfree(ptes);
return 0;
}
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, start * ssz, size * ssz);
/* If this is a RAID volume, tell md */
if (!efi_guidcmp(ptes[i].partition_type_guid,
PARTITION_LINUX_RAID_GUID))
state->parts[i+1].flags = 1;
}
kfree(ptes);
kfree(gpt);
printk("\n");
return 1;
}
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