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linux/fs/partitions/efi.c

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/************************************************************
* EFI GUID Partition Table handling
* Per Intel EFI Specification v1.02
* http://developer.intel.com/technology/efi/efi.htm
* 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 "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 (bdev->bd_inode->i_size >> 9) - 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;
if (!bdev || !buffer || lba > last_lba(bdev))
return 0;
while (count) {
int copied = 512;
Sector sect;
unsigned char *data = read_dev_sector(bdev, lba++, &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;
if (!bdev)
return NULL;
gpt = kzalloc(sizeof (gpt_header), GFP_KERNEL);
if (!gpt)
return NULL;
if (read_lba(bdev, lba, (u8 *) gpt,
sizeof (gpt_header)) < sizeof (gpt_header)) {
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;
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++) {
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));
/* 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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