efi.c

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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 <[email protected]>
 *   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 <[email protected]>
 * - 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 <[email protected]>
 * - 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 <[email protected]>
 * - Removed __PRIPTR_PREFIX - not being used
 *
 * Mon  Jan 14 2002 Matt Domsch <[email protected]>
 * - Ported to 2.5.2-pre11 + library crc32 patch Linus applied
 *
 * Thu Dec 6 2001 Matt Domsch <[email protected]>
 * - 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 <[email protected]>
 * - Removed CONFIG_DEVFS_VOLUMES_UUID code entirely per Martin Wilck
 *
 * Wed Oct 10 2001 Matt Domsch <[email protected]>
 * - Changed function comments to DocBook style per Andreas Dilger suggestion.
 *
 * Mon Oct 08 2001 Matt Domsch <[email protected]>
 * - 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 <[email protected]>
 * - 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 <[email protected]>
 * - added devfs volume UUID support (/dev/volumes/uuids) for
 *   mounting file systems by the partition GUID. 
 *
 * Tue Dec  5 2000 Matt Domsch <[email protected]>
 * - Moved crc32() to linux/lib, added efi_crc32().
 *
 * Thu Nov 30 2000 Matt Domsch <[email protected]>
 * - Replaced Intel's CRC32 function with an equivalent
 *   non-license-restricted version.
 *
 * Wed Oct 25 2000 Matt Domsch <[email protected]>
 * - Fixed the last_lba() call to return the proper last block
 *
 * Thu Oct 12 2000 Matt Domsch <[email protected]>
 * - Thanks to Andries Brouwer for his debugging assistance.
 * - Code works, detects all the partitions.
 *
 ************************************************************/
#include <linux/crc32.h>
#include <linux/ctype.h>
#include <linux/math64.h>
#include <linux/slab.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);


static inline u32
efi_crc32(const void *buf, unsigned long len)
{
    return (crc32(~0L, buf, len) ^ ~0L);
}

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;
}

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;
}

static size_t read_lba(struct parsed_partitions *state,
               u64 lba, u8 *buffer, size_t count)
{
    size_t totalreadcount = 0;
    struct block_device *bdev = state->bdev;
    sector_t n = lba * (bdev_logical_block_size(bdev) / 512);

    if (!buffer || lba > last_lba(bdev))
                return 0;

    while (count) {
        int copied = 512;
        Sector sect;
        unsigned char *data = read_part_sector(state, 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;
}

static gpt_entry *alloc_read_gpt_entries(struct parsed_partitions *state,
                     gpt_header *gpt)
{
    size_t count;
    gpt_entry *pte;

    if (!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(state, le64_to_cpu(gpt->partition_entry_lba),
                     (u8 *) pte,
             count) < count) {
        kfree(pte);
                pte=NULL;
        return NULL;
    }
    return pte;
}

static gpt_header *alloc_read_gpt_header(struct parsed_partitions *state,
                     u64 lba)
{
    gpt_header *gpt;
    unsigned ssz = bdev_logical_block_size(state->bdev);

    gpt = kzalloc(ssz, GFP_KERNEL);
    if (!gpt)
        return NULL;

    if (read_lba(state, lba, (u8 *) gpt, ssz) < ssz) {
        kfree(gpt);
                gpt=NULL;
        return NULL;
    }

    return gpt;
}

static int is_gpt_valid(struct parsed_partitions *state, u64 lba,
            gpt_header **gpt, gpt_entry **ptes)
{
    u32 crc, origcrc;
    u64 lastlba;

    if (!ptes)
        return 0;
    if (!(*gpt = alloc_read_gpt_header(state, 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 header size */
    if (le32_to_cpu((*gpt)->header_size) >
            bdev_logical_block_size(state->bdev)) {
        pr_debug("GUID Partition Table Header size is wrong: %u > %u\n",
            le32_to_cpu((*gpt)->header_size),
            bdev_logical_block_size(state->bdev));
        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(state->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;
    }

    /* Check that sizeof_partition_entry has the correct value */
    if (le32_to_cpu((*gpt)->sizeof_partition_entry) != sizeof(gpt_entry)) {
        pr_debug("GUID Partitition Entry Size check failed.\n");
        goto fail;
    }

    if (!(*ptes = alloc_read_gpt_entries(state, *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;
}

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;
}

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;
}

static int find_valid_gpt(struct parsed_partitions *state, 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 (!ptes)
        return 0;

    lastlba = last_lba(state->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(state, 0, (u8 *) legacymbr,
                 sizeof (*legacymbr));
                        good_pmbr = is_pmbr_valid(legacymbr);
                        kfree(legacymbr);
                }
                if (!good_pmbr)
                        goto fail;
        }

    good_pgpt = is_gpt_valid(state, GPT_PRIMARY_PARTITION_TABLE_LBA,
                 &pgpt, &pptes);
        if (good_pgpt)
        good_agpt = is_gpt_valid(state,
                     le64_to_cpu(pgpt->alternate_lba),
                     &agpt, &aptes);
        if (!good_agpt && force_gpt)
                good_agpt = is_gpt_valid(state, 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;
}

int efi_partition(struct parsed_partitions *state)
{
    gpt_header *gpt = NULL;
    gpt_entry *ptes = NULL;
    u32 i;
    unsigned ssz = bdev_logical_block_size(state->bdev) / 512;
    u8 unparsed_guid[37];

    if (!find_valid_gpt(state, &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++) {
        struct partition_meta_info *info;
        unsigned label_count = 0;
        unsigned label_max;
        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(state->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 = ADDPART_FLAG_RAID;

        info = &state->parts[i + 1].info;
        /* Instead of doing a manual swap to big endian, reuse the
         * common ASCII hex format as the interim.
         */
        efi_guid_unparse(&ptes[i].unique_partition_guid, unparsed_guid);
        part_pack_uuid(unparsed_guid, info->uuid);

        /* Naively convert UTF16-LE to 7 bits. */
        label_max = min(sizeof(info->volname) - 1,
                sizeof(ptes[i].partition_name));
        info->volname[label_max] = 0;
        while (label_count < label_max) {
            u8 c = ptes[i].partition_name[label_count] & 0xff;
            if (c && !isprint(c))
                c = '!';
            info->volname[label_count] = c;
            label_count++;
        }
        state->parts[i + 1].has_info = true;
    }
    kfree(ptes);
    kfree(gpt);
    strlcat(state->pp_buf, "\n", PAGE_SIZE);
    return 1;
}