boot/common/gpt.c

	gpt.c revision 199767f8919635c4928607450d9e0abb932109ce
/*-
 * Copyright (c) 2010 Pawel Jakub Dawidek <pjd@FreeBSD.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include <sys/param.h>
#include <sys/gpt.h>

#ifndef LITTLE_ENDIAN
#error gpt.c works only for little endian architectures
#endif

#include "crc32.h"
#include "drv.h"
#include "util.h"
#include "gpt.h"

#define MAXTBLENTS  128

static struct gpt_hdr hdr_primary, hdr_backup, *gpthdr;
static uint64_t hdr_primary_lba, hdr_backup_lba;
static struct gpt_ent table_primary[MAXTBLENTS], table_backup[MAXTBLENTS];
static struct gpt_ent *gpttable;
static int curent, bootonce;

/*
 * Buffer below 64kB passed on gptread(), which can hold at least
 * one sector of data (512 bytes).
 */
static char *secbuf;

static void
gptupdate(const char *which, struct dsk *dskp, struct gpt_hdr *hdr,
    struct gpt_ent *table)
{
    int entries_per_sec, firstent;
    daddr_t slba;

    /*
     * We need to update the following for both primary and backup GPT:
     * 1. Sector on disk that contains current partition.
     * 2. Partition table checksum.
     * 3. Header checksum.
     * 4. Header on disk.
     */

    entries_per_sec = DEV_BSIZE / hdr->hdr_entsz;
    slba = curent / entries_per_sec;
    firstent = slba * entries_per_sec;
    bcopy(&table[firstent], secbuf, DEV_BSIZE);
    slba += hdr->hdr_lba_table;
    if (drvwrite(dskp, secbuf, slba, 1)) {
        printf("%s: unable to update %s GPT partition table\n",
            BOOTPROG, which);
        return;
    }
    hdr->hdr_crc_table = crc32(table, hdr->hdr_entries * hdr->hdr_entsz);
    hdr->hdr_crc_self = 0;
    hdr->hdr_crc_self = crc32(hdr, hdr->hdr_size);
    bzero(secbuf, DEV_BSIZE);
    bcopy(hdr, secbuf, hdr->hdr_size);
    if (drvwrite(dskp, secbuf, hdr->hdr_lba_self, 1)) {
        printf("%s: unable to update %s GPT header\n", BOOTPROG, which);
        return;
    }
}

int
gptfind(const uuid_t *uuid, struct dsk *dskp, int part)
{
    struct gpt_ent *ent;
    int firsttry;

    if (part >= 0) {
        if (part == 0 || part > gpthdr->hdr_entries) {
            printf("%s: invalid partition index\n", BOOTPROG);
            return (-1);
        }
        ent = &gpttable[part - 1];
        if (bcmp(&ent->ent_type, uuid, sizeof(uuid_t)) != 0) {
            printf("%s: specified partition is not UFS\n",
                BOOTPROG);
            return (-1);
        }
        curent = part - 1;
        goto found;
    }

    firsttry = (curent == -1);
    curent++;
    if (curent >= gpthdr->hdr_entries) {
        curent = gpthdr->hdr_entries;
        return (-1);
    }
    if (bootonce) {
        /*
         * First look for partition with both GPT_ENT_ATTR_BOOTME and
         * GPT_ENT_ATTR_BOOTONCE flags.
         */
        for (; curent < gpthdr->hdr_entries; curent++) {
            ent = &gpttable[curent];
            if (bcmp(&ent->ent_type, uuid, sizeof(uuid_t)) != 0)
                continue;
            if (!(ent->ent_attr & GPT_ENT_ATTR_BOOTME))
                continue;
            if (!(ent->ent_attr & GPT_ENT_ATTR_BOOTONCE))
                continue;
            /* Ok, found one. */
            goto found;
        }
        bootonce = 0;
        curent = 0;
    }
    for (; curent < gpthdr->hdr_entries; curent++) {
        ent = &gpttable[curent];
        if (bcmp(&ent->ent_type, uuid, sizeof(uuid_t)) != 0)
            continue;
        if (!(ent->ent_attr & GPT_ENT_ATTR_BOOTME))
            continue;
        if (ent->ent_attr & GPT_ENT_ATTR_BOOTONCE)
            continue;
        /* Ok, found one. */
        goto found;
    }
    if (firsttry) {
        /*
         * No partition with BOOTME flag was found, try to boot from
         * first UFS partition.
         */
        for (curent = 0; curent < gpthdr->hdr_entries; curent++) {
            ent = &gpttable[curent];
            if (bcmp(&ent->ent_type, uuid, sizeof(uuid_t)) != 0)
                continue;
            /* Ok, found one. */
            goto found;
        }
    }
    return (-1);
found:
    dskp->part = curent + 1;
    ent = &gpttable[curent];
    dskp->start = ent->ent_lba_start;
    if (ent->ent_attr & GPT_ENT_ATTR_BOOTONCE) {
        /*
         * Clear BOOTME, but leave BOOTONCE set before trying to
         * boot from this partition.
         */
        if (hdr_primary_lba > 0) {
            table_primary[curent].ent_attr &= ~GPT_ENT_ATTR_BOOTME;
            gptupdate("primary", dskp, &hdr_primary, table_primary);
        }
        if (hdr_backup_lba > 0) {
            table_backup[curent].ent_attr &= ~GPT_ENT_ATTR_BOOTME;
            gptupdate("backup", dskp, &hdr_backup, table_backup);
        }
    }
    return (0);
}

static int
gptread_hdr(const char *which, struct dsk *dskp, struct gpt_hdr *hdr,
    uint64_t hdrlba)
{
    uint32_t crc;

    if (drvread(dskp, secbuf, hdrlba, 1)) {
        printf("%s: unable to read %s GPT header\n", BOOTPROG, which);
        return (-1);
    }
    bcopy(secbuf, hdr, sizeof(*hdr));
    if (bcmp(hdr->hdr_sig, GPT_HDR_SIG, sizeof(hdr->hdr_sig)) != 0 ||
        hdr->hdr_lba_self != hdrlba || hdr->hdr_revision < 0x00010000 ||
        hdr->hdr_entsz < sizeof(struct gpt_ent) ||
        hdr->hdr_entries > MAXTBLENTS || DEV_BSIZE % hdr->hdr_entsz != 0) {
        printf("%s: invalid %s GPT header\n", BOOTPROG, which);
        return (-1);
    }
    crc = hdr->hdr_crc_self;
    hdr->hdr_crc_self = 0;
    if (crc32(hdr, hdr->hdr_size) != crc) {
        printf("%s: %s GPT header checksum mismatch\n", BOOTPROG,
            which);
        return (-1);
    }
    hdr->hdr_crc_self = crc;
    return (0);
}

void
gptbootfailed(struct dsk *dskp)
{

    if (!(gpttable[curent].ent_attr & GPT_ENT_ATTR_BOOTONCE))
        return;

    if (hdr_primary_lba > 0) {
        table_primary[curent].ent_attr &= ~GPT_ENT_ATTR_BOOTONCE;
        table_primary[curent].ent_attr |= GPT_ENT_ATTR_BOOTFAILED;
        gptupdate("primary", dskp, &hdr_primary, table_primary);
    }
    if (hdr_backup_lba > 0) {
        table_backup[curent].ent_attr &= ~GPT_ENT_ATTR_BOOTONCE;
        table_backup[curent].ent_attr |= GPT_ENT_ATTR_BOOTFAILED;
        gptupdate("backup", dskp, &hdr_backup, table_backup);
    }
}

static void
gptbootconv(const char *which, struct dsk *dskp, struct gpt_hdr *hdr,
    struct gpt_ent *table)
{
    struct gpt_ent *ent;
    daddr_t slba;
    int table_updated, sector_updated;
    int entries_per_sec, nent, part;

    table_updated = 0;
    entries_per_sec = DEV_BSIZE / hdr->hdr_entsz;
    for (nent = 0, slba = hdr->hdr_lba_table;
         slba < hdr->hdr_lba_table + hdr->hdr_entries / entries_per_sec;
         slba++, nent += entries_per_sec) {
        sector_updated = 0;
        for (part = 0; part < entries_per_sec; part++) {
            ent = &table[nent + part];
            if ((ent->ent_attr & (GPT_ENT_ATTR_BOOTME |
                GPT_ENT_ATTR_BOOTONCE |
                GPT_ENT_ATTR_BOOTFAILED)) !=
                GPT_ENT_ATTR_BOOTONCE) {
                continue;
            }
            ent->ent_attr &= ~GPT_ENT_ATTR_BOOTONCE;
            ent->ent_attr |= GPT_ENT_ATTR_BOOTFAILED;
            table_updated = 1;
            sector_updated = 1;
        }
        if (!sector_updated)
            continue;
        bcopy(&table[nent], secbuf, DEV_BSIZE);
        if (drvwrite(dskp, secbuf, slba, 1)) {
            printf("%s: unable to update %s GPT partition table\n",
                BOOTPROG, which);
        }
    }
    if (!table_updated)
        return;
    hdr->hdr_crc_table = crc32(table, hdr->hdr_entries * hdr->hdr_entsz);
    hdr->hdr_crc_self = 0;
    hdr->hdr_crc_self = crc32(hdr, hdr->hdr_size);
    bzero(secbuf, DEV_BSIZE);
    bcopy(hdr, secbuf, hdr->hdr_size);
    if (drvwrite(dskp, secbuf, hdr->hdr_lba_self, 1))
        printf("%s: unable to update %s GPT header\n", BOOTPROG, which);
}

static int
gptread_table(const char *which, const uuid_t *uuid, struct dsk *dskp,
    struct gpt_hdr *hdr, struct gpt_ent *table)
{
    struct gpt_ent *ent;
    int entries_per_sec;
    int part, nent;
    daddr_t slba;

    if (hdr->hdr_entries == 0)
        return (0);

    entries_per_sec = DEV_BSIZE / hdr->hdr_entsz;
    slba = hdr->hdr_lba_table;
    nent = 0;
    for (;;) {
        if (drvread(dskp, secbuf, slba, 1)) {
            printf("%s: unable to read %s GPT partition table\n",
                BOOTPROG, which);
            return (-1);
        }
        ent = (struct gpt_ent *)secbuf;
        for (part = 0; part < entries_per_sec; part++, ent++) {
            bcopy(ent, &table[nent], sizeof(table[nent]));
            if (++nent >= hdr->hdr_entries)
                break;
        }
        if (nent >= hdr->hdr_entries)
            break;
        slba++;
    }
    if (crc32(table, nent * hdr->hdr_entsz) != hdr->hdr_crc_table) {
        printf("%s: %s GPT table checksum mismatch\n", BOOTPROG, which);
        return (-1);
    }
    return (0);
}

int
gptread(const uuid_t *uuid, struct dsk *dskp, char *buf)
{
    uint64_t altlba;

    /*
     * Read and verify both GPT headers: primary and backup.
     */

    secbuf = buf;
    hdr_primary_lba = hdr_backup_lba = 0;
    curent = -1;
    bootonce = 1;
    dskp->start = 0;

    if (gptread_hdr("primary", dskp, &hdr_primary, 1) == 0 &&
        gptread_table("primary", uuid, dskp, &hdr_primary,
        table_primary) == 0) {
        hdr_primary_lba = hdr_primary.hdr_lba_self;
        gpthdr = &hdr_primary;
        gpttable = table_primary;
    }

    if (hdr_primary_lba > 0) {
        /*
         * If primary header is valid, we can get backup
         * header location from there.
         */
        altlba = hdr_primary.hdr_lba_alt;
    } else {
        altlba = drvsize(dskp);
        if (altlba > 0)
            altlba--;
    }
    if (altlba == 0)
        printf("%s: unable to locate backup GPT header\n", BOOTPROG);
    else if (gptread_hdr("backup", dskp, &hdr_backup, altlba) == 0 &&
        gptread_table("backup", uuid, dskp, &hdr_backup,
        table_backup) == 0) {
        hdr_backup_lba = hdr_backup.hdr_lba_self;
        if (hdr_primary_lba == 0) {
            gpthdr = &hdr_backup;
            gpttable = table_backup;
            printf("%s: using backup GPT\n", BOOTPROG);
        }
    }

    /*
     * Convert all BOOTONCE without BOOTME flags into BOOTFAILED.
     * BOOTONCE without BOOTME means that we tried to boot from it,
     * but failed after leaving gptboot and machine was rebooted.
     * We don't want to leave partitions marked as BOOTONCE only,
     * because when we boot successfully start-up scripts should
     * find at most one partition with only BOOTONCE flag and this
     * will mean that we booted from that partition.
     */
    if (hdr_primary_lba != 0)
        gptbootconv("primary", dskp, &hdr_primary, table_primary);
    if (hdr_backup_lba != 0)
        gptbootconv("backup", dskp, &hdr_backup, table_backup);

    if (hdr_primary_lba == 0 && hdr_backup_lba == 0)
        return (-1);
    return (0);
}