// SPDX-License-Identifier: GPL-2.0
/*
 *  fs/partitions/msdos.c
 *
 *  Code extracted from drivers/block/genhd.c
 *  Copyright (C) 1991-1998  Linus Torvalds
 *
 *  Thanks to Branko Lankester, lankeste@fwi.uva.nl, who found a bug
 *  in the early extended-partition checks and added DM partitions
 *
 *  Support for DiskManager v6.0x added by Mark Lord,
 *  with information provided by OnTrack.  This now works for linux fdisk
 *  and LILO, as well as loadlin and bootln.  Note that disks other than
 *  /dev/hda *must* have a "DOS" type 0x51 partition in the first slot (hda1).
 *
 *  More flexible handling of extended partitions - aeb, 950831
 *
 *  Check partition table on IDE disks for common CHS translations
 *
 *  Re-organised Feb 1998 Russell King
 */
#include <linux/msdos_fs.h>

#include "check.h"
#include "msdos.h"
#include "efi.h"
#include "aix.h"

/*
 * Many architectures don't like unaligned accesses, while
 * the nr_sects and start_sect partition table entries are
 * at a 2 (mod 4) address.
 */
#include <asm/unaligned.h>

#define SYS_IND(p)      get_unaligned(&p->sys_ind)

static inline sector_t nr_sects(struct partition *p)
{
        return (sector_t)get_unaligned_le32(&p->nr_sects);
}

static inline sector_t start_sect(struct partition *p)
{
        return (sector_t)get_unaligned_le32(&p->start_sect);
}

static inline int is_extended_partition(struct partition *p)
{
        return (SYS_IND(p) == DOS_EXTENDED_PARTITION ||
                SYS_IND(p) == WIN98_EXTENDED_PARTITION ||
                SYS_IND(p) == LINUX_EXTENDED_PARTITION);
}

#define MSDOS_LABEL_MAGIC1      0x55
#define MSDOS_LABEL_MAGIC2      0xAA

static inline int
msdos_magic_present(unsigned char *p)
{
        return (p[0] == MSDOS_LABEL_MAGIC1 && p[1] == MSDOS_LABEL_MAGIC2);
}

/* Value is EBCDIC 'IBMA' */
#define AIX_LABEL_MAGIC1        0xC9
#define AIX_LABEL_MAGIC2        0xC2
#define AIX_LABEL_MAGIC3        0xD4
#define AIX_LABEL_MAGIC4        0xC1
static int aix_magic_present(struct parsed_partitions *state, unsigned char *p)
{
        struct partition *pt = (struct partition *) (p + 0x1be);
        Sector sect;
        unsigned char *d;
        int slot, ret = 0;

        if (!(p[0] == AIX_LABEL_MAGIC1 &&
                p[1] == AIX_LABEL_MAGIC2 &&
                p[2] == AIX_LABEL_MAGIC3 &&
                p[3] == AIX_LABEL_MAGIC4))
                return 0;
        /* Assume the partition table is valid if Linux partitions exists */
        for (slot = 1; slot <= 4; slot++, pt++) {
                if (pt->sys_ind == LINUX_SWAP_PARTITION ||
                        pt->sys_ind == LINUX_RAID_PARTITION ||
                        pt->sys_ind == LINUX_DATA_PARTITION ||
                        pt->sys_ind == LINUX_LVM_PARTITION ||
                        is_extended_partition(pt))
                        return 0;
        }
        d = read_part_sector(state, 7, &sect);
        if (d) {
                if (d[0] == '_' && d[1] == 'L' && d[2] == 'V' && d[3] == 'M')
                        ret = 1;
                put_dev_sector(sect);
        }
        return ret;
}

static void set_info(struct parsed_partitions *state, int slot,
                     u32 disksig)
{
        struct partition_meta_info *info = &state->parts[slot].info;

        snprintf(info->uuid, sizeof(info->uuid), "%08x-%02x", disksig,
                 slot);
        info->volname[0] = 0;
        state->parts[slot].has_info = true;
}

/*
 * Create devices for each logical partition in an extended partition.
 * The logical partitions form a linked list, with each entry being
 * a partition table with two entries.  The first entry
 * is the real data partition (with a start relative to the partition
 * table start).  The second is a pointer to the next logical partition
 * (with a start relative to the entire extended partition).
 * We do not create a Linux partition for the partition tables, but
 * only for the actual data partitions.
 */

static void parse_extended(struct parsed_partitions *state,
                           sector_t first_sector, sector_t first_size,
                           u32 disksig)
{
        struct partition *p;
        Sector sect;
        unsigned char *data;
        sector_t this_sector, this_size;
        sector_t sector_size = bdev_logical_block_size(state->bdev) / 512;
        int loopct = 0;         /* number of links followed
                                   without finding a data partition */
        int i;

        this_sector = first_sector;
        this_size = first_size;

        while (1) {
                if (++loopct > 100)
                        return;
                if (state->next == state->limit)
                        return;
                data = read_part_sector(state, this_sector, &sect);
                if (!data)
                        return;

                if (!msdos_magic_present(data + 510))
                        goto done;

                p = (struct partition *) (data + 0x1be);

                /*
                 * Usually, the first entry is the real data partition,
                 * the 2nd entry is the next extended partition, or empty,
                 * and the 3rd and 4th entries are unused.
                 * However, DRDOS sometimes has the extended partition as
                 * the first entry (when the data partition is empty),
                 * and OS/2 seems to use all four entries.
                 */

                /*
                 * First process the data partition(s)
                 */
                for (i = 0; i < 4; i++, p++) {
                        sector_t offs, size, next;

                        if (!nr_sects(p) || is_extended_partition(p))
                                continue;

                        /* Check the 3rd and 4th entries -
                           these sometimes contain random garbage */
                        offs = start_sect(p)*sector_size;
                        size = nr_sects(p)*sector_size;
                        next = this_sector + offs;
                        if (i >= 2) {
                                if (offs + size > this_size)
                                        continue;
                                if (next < first_sector)
                                        continue;
                                if (next + size > first_sector + first_size)
                                        continue;
                        }

                        put_partition(state, state->next, next, size);
                        set_info(state, state->next, disksig);
                        if (SYS_IND(p) == LINUX_RAID_PARTITION)
                                state->parts[state->next].flags = ADDPART_FLAG_RAID;
                        loopct = 0;
                        if (++state->next == state->limit)
                                goto done;
                }
                /*
                 * Next, process the (first) extended partition, if present.
                 * (So far, there seems to be no reason to make
                 *  parse_extended()  recursive and allow a tree
                 *  of extended partitions.)
                 * It should be a link to the next logical partition.
                 */
                p -= 4;
                for (i = 0; i < 4; i++, p++)
                        if (nr_sects(p) && is_extended_partition(p))
                                break;
                if (i == 4)
                        goto done;       /* nothing left to do */

                this_sector = first_sector + start_sect(p) * sector_size;
                this_size = nr_sects(p) * sector_size;
                put_dev_sector(sect);
        }
done:
        put_dev_sector(sect);
}

/* james@bpgc.com: Solaris has a nasty indicator: 0x82 which also
   indicates linux swap.  Be careful before believing this is Solaris. */

static void parse_solaris_x86(struct parsed_partitions *state,
                              sector_t offset, sector_t size, int origin)
{
#ifdef CONFIG_SOLARIS_X86_PARTITION
        Sector sect;
        struct solaris_x86_vtoc *v;
        int i;
        short max_nparts;

        v = read_part_sector(state, offset + 1, &sect);
        if (!v)
                return;
        if (le32_to_cpu(v->v_sanity) != SOLARIS_X86_VTOC_SANE) {
                put_dev_sector(sect);
                return;
        }
        {
                char tmp[1 + BDEVNAME_SIZE + 10 + 11 + 1];

                snprintf(tmp, sizeof(tmp), " %s%d: <solaris:", state->name, origin);
                strlcat(state->pp_buf, tmp, PAGE_SIZE);
        }
        if (le32_to_cpu(v->v_version) != 1) {
                char tmp[64];

                snprintf(tmp, sizeof(tmp), "  cannot handle version %d vtoc>\n",
                         le32_to_cpu(v->v_version));
                strlcat(state->pp_buf, tmp, PAGE_SIZE);
                put_dev_sector(sect);
                return;
        }
        /* Ensure we can handle previous case of VTOC with 8 entries gracefully */
        max_nparts = le16_to_cpu(v->v_nparts) > 8 ? SOLARIS_X86_NUMSLICE : 8;
        for (i = 0; i < max_nparts && state->next < state->limit; i++) {
                struct solaris_x86_slice *s = &v->v_slice[i];
                char tmp[3 + 10 + 1 + 1];

                if (s->s_size == 0)
                        continue;
                snprintf(tmp, sizeof(tmp), " [s%d]", i);
                strlcat(state->pp_buf, tmp, PAGE_SIZE);
                /* solaris partitions are relative to current MS-DOS
                 * one; must add the offset of the current partition */
                put_partition(state, state->next++,
                                 le32_to_cpu(s->s_start)+offset,
                                 le32_to_cpu(s->s_size));
        }
        put_dev_sector(sect);
        strlcat(state->pp_buf, " >\n", PAGE_SIZE);
#endif
}

#if defined(CONFIG_BSD_DISKLABEL)
/*
 * Create devices for BSD partitions listed in a disklabel, under a
 * dos-like partition. See parse_extended() for more information.
 */
static void parse_bsd(struct parsed_partitions *state,
                      sector_t offset, sector_t size, int origin, char *flavour,
                      int max_partitions)
{
        Sector sect;
        struct bsd_disklabel *l;
        struct bsd_partition *p;
        char tmp[64];

        l = read_part_sector(state, offset + 1, &sect);
        if (!l)
                return;
        if (le32_to_cpu(l->d_magic) != BSD_DISKMAGIC) {
                put_dev_sector(sect);
                return;
        }

        snprintf(tmp, sizeof(tmp), " %s%d: <%s:", state->name, origin, flavour);
        strlcat(state->pp_buf, tmp, PAGE_SIZE);

        if (le16_to_cpu(l->d_npartitions) < max_partitions)
                max_partitions = le16_to_cpu(l->d_npartitions);
        for (p = l->d_partitions; p - l->d_partitions < max_partitions; p++) {
                sector_t bsd_start, bsd_size;

                if (state->next == state->limit)
                        break;
                if (p->p_fstype == BSD_FS_UNUSED)
                        continue;
                bsd_start = le32_to_cpu(p->p_offset);
                bsd_size = le32_to_cpu(p->p_size);
                /* FreeBSD has relative offset if C partition offset is zero */
                if (memcmp(flavour, "bsd\0", 4) == 0 &&
                    le32_to_cpu(l->d_partitions[2].p_offset) == 0)
                        bsd_start += offset;
                if (offset == bsd_start && size == bsd_size)
                        /* full parent partition, we have it already */
                        continue;
                if (offset > bsd_start || offset+size < bsd_start+bsd_size) {
                        strlcat(state->pp_buf, "bad subpartition - ignored\n", PAGE_SIZE);
                        continue;
                }
                put_partition(state, state->next++, bsd_start, bsd_size);
        }
        put_dev_sector(sect);
        if (le16_to_cpu(l->d_npartitions) > max_partitions) {
                snprintf(tmp, sizeof(tmp), " (ignored %d more)",
                         le16_to_cpu(l->d_npartitions) - max_partitions);
                strlcat(state->pp_buf, tmp, PAGE_SIZE);
        }
        strlcat(state->pp_buf, " >\n", PAGE_SIZE);
}
#endif

static void parse_freebsd(struct parsed_partitions *state,
                          sector_t offset, sector_t size, int origin)
{
#ifdef CONFIG_BSD_DISKLABEL
        parse_bsd(state, offset, size, origin, "bsd", BSD_MAXPARTITIONS);
#endif
}

static void parse_netbsd(struct parsed_partitions *state,
                         sector_t offset, sector_t size, int origin)
{
#ifdef CONFIG_BSD_DISKLABEL
        parse_bsd(state, offset, size, origin, "netbsd", BSD_MAXPARTITIONS);
#endif
}

static void parse_openbsd(struct parsed_partitions *state,
                          sector_t offset, sector_t size, int origin)
{
#ifdef CONFIG_BSD_DISKLABEL
        parse_bsd(state, offset, size, origin, "openbsd",
                  OPENBSD_MAXPARTITIONS);
#endif
}

/*
 * Create devices for Unixware partitions listed in a disklabel, under a
 * dos-like partition. See parse_extended() for more information.
 */
static void parse_unixware(struct parsed_partitions *state,
                           sector_t offset, sector_t size, int origin)
{
#ifdef CONFIG_UNIXWARE_DISKLABEL
        Sector sect;
        struct unixware_disklabel *l;
        struct unixware_slice *p;

        l = read_part_sector(state, offset + 29, &sect);
        if (!l)
                return;
        if (le32_to_cpu(l->d_magic) != UNIXWARE_DISKMAGIC ||
            le32_to_cpu(l->vtoc.v_magic) != UNIXWARE_DISKMAGIC2) {
                put_dev_sector(sect);
                return;
        }
        {
                char tmp[1 + BDEVNAME_SIZE + 10 + 12 + 1];

                snprintf(tmp, sizeof(tmp), " %s%d: <unixware:", state->name, origin);
                strlcat(state->pp_buf, tmp, PAGE_SIZE);
        }
        p = &l->vtoc.v_slice[1];
        /* I omit the 0th slice as it is the same as whole disk. */
        while (p - &l->vtoc.v_slice[0] < UNIXWARE_NUMSLICE) {
                if (state->next == state->limit)
                        break;

                if (p->s_label != UNIXWARE_FS_UNUSED)
                        put_partition(state, state->next++,
                                      le32_to_cpu(p->start_sect),
                                      le32_to_cpu(p->nr_sects));
                p++;
        }
        put_dev_sector(sect);
        strlcat(state->pp_buf, " >\n", PAGE_SIZE);
#endif
}

/*
 * Minix 2.0.0/2.0.2 subpartition support.
 * Anand Krishnamurthy <anandk@wiproge.med.ge.com>
 * Rajeev V. Pillai    <rajeevvp@yahoo.com>
 */
static void parse_minix(struct parsed_partitions *state,
                        sector_t offset, sector_t size, int origin)
{
#ifdef CONFIG_MINIX_SUBPARTITION
        Sector sect;
        unsigned char *data;
        struct partition *p;
        int i;

        data = read_part_sector(state, offset, &sect);
        if (!data)
                return;

        p = (struct partition *)(data + 0x1be);

        /* The first sector of a Minix partition can have either
         * a secondary MBR describing its subpartitions, or
         * the normal boot sector. */
        if (msdos_magic_present(data + 510) &&
            SYS_IND(p) == MINIX_PARTITION) { /* subpartition table present */
                char tmp[1 + BDEVNAME_SIZE + 10 + 9 + 1];

                snprintf(tmp, sizeof(tmp), " %s%d: <minix:", state->name, origin);
                strlcat(state->pp_buf, tmp, PAGE_SIZE);
                for (i = 0; i < MINIX_NR_SUBPARTITIONS; i++, p++) {
                        if (state->next == state->limit)
                                break;
                        /* add each partition in use */
                        if (SYS_IND(p) == MINIX_PARTITION)
                                put_partition(state, state->next++,
                                              start_sect(p), nr_sects(p));
                }
                strlcat(state->pp_buf, " >\n", PAGE_SIZE);
        }
        put_dev_sector(sect);
#endif /* CONFIG_MINIX_SUBPARTITION */
}

static struct {
        unsigned char id;
        void (*parse)(struct parsed_partitions *, sector_t, sector_t, int);
} subtypes[] = {
        {FREEBSD_PARTITION, parse_freebsd},
        {NETBSD_PARTITION, parse_netbsd},
        {OPENBSD_PARTITION, parse_openbsd},
        {MINIX_PARTITION, parse_minix},
        {UNIXWARE_PARTITION, parse_unixware},
        {SOLARIS_X86_PARTITION, parse_solaris_x86},
        {NEW_SOLARIS_X86_PARTITION, parse_solaris_x86},
        {0, NULL},
};

int msdos_partition(struct parsed_partitions *state)
{
        sector_t sector_size = bdev_logical_block_size(state->bdev) / 512;
        Sector sect;
        unsigned char *data;
        struct partition *p;
        struct fat_boot_sector *fb;
        int slot;
        u32 disksig;

        data = read_part_sector(state, 0, &sect);
        if (!data)
                return -1;

        /*
         * Note order! (some AIX disks, e.g. unbootable kind,
         * have no MSDOS 55aa)
         */
        if (aix_magic_present(state, data)) {
                put_dev_sector(sect);
#ifdef CONFIG_AIX_PARTITION
                return aix_partition(state);
#else
                strlcat(state->pp_buf, " [AIX]", PAGE_SIZE);
                return 0;
#endif
        }

        if (!msdos_magic_present(data + 510)) {
                put_dev_sector(sect);
                return 0;
        }

        /*
         * Now that the 55aa signature is present, this is probably
         * either the boot sector of a FAT filesystem or a DOS-type
         * partition table. Reject this in case the boot indicator
         * is not 0 or 0x80.
         */
        p = (struct partition *) (data + 0x1be);
        for (slot = 1; slot <= 4; slot++, p++) {
                if (p->boot_ind != 0 && p->boot_ind != 0x80) {
                        /*
                         * Even without a valid boot inidicator value
                         * its still possible this is valid FAT filesystem
                         * without a partition table.
                         */
                        fb = (struct fat_boot_sector *) data;
                        if (slot == 1 && fb->reserved && fb->fats
                                && fat_valid_media(fb->media)) {
                                strlcat(state->pp_buf, "\n", PAGE_SIZE);
                                put_dev_sector(sect);
                                return 1;
                        } else {
                                put_dev_sector(sect);
                                return 0;
                        }
                }
        }

#ifdef CONFIG_EFI_PARTITION
        p = (struct partition *) (data + 0x1be);
        for (slot = 1 ; slot <= 4 ; slot++, p++) {
                /* If this is an EFI GPT disk, msdos should ignore it. */
                if (SYS_IND(p) == EFI_PMBR_OSTYPE_EFI_GPT) {
                        put_dev_sector(sect);
                        return 0;
                }
        }
#endif
        p = (struct partition *) (data + 0x1be);

        disksig = le32_to_cpup((__le32 *)(data + 0x1b8));

        /*
         * Look for partitions in two passes:
         * First find the primary and DOS-type extended partitions.
         * On the second pass look inside *BSD, Unixware and Solaris partitions.
         */

        state->next = 5;
        for (slot = 1 ; slot <= 4 ; slot++, p++) {
                sector_t start = start_sect(p)*sector_size;
                sector_t size = nr_sects(p)*sector_size;

                if (!size)
                        continue;
                if (is_extended_partition(p)) {
                        /*
                         * prevent someone doing mkfs or mkswap on an
                         * extended partition, but leave room for LILO
                         * FIXME: this uses one logical sector for > 512b
                         * sector, although it may not be enough/proper.
                         */
                        sector_t n = 2;

                        n = min(size, max(sector_size, n));
                        put_partition(state, slot, start, n);

                        strlcat(state->pp_buf, " <", PAGE_SIZE);
                        parse_extended(state, start, size, disksig);
                        strlcat(state->pp_buf, " >", PAGE_SIZE);
                        continue;
                }
                put_partition(state, slot, start, size);
                set_info(state, slot, disksig);
                if (SYS_IND(p) == LINUX_RAID_PARTITION)
                        state->parts[slot].flags = ADDPART_FLAG_RAID;
                if (SYS_IND(p) == DM6_PARTITION)
                        strlcat(state->pp_buf, "[DM]", PAGE_SIZE);
                if (SYS_IND(p) == EZD_PARTITION)
                        strlcat(state->pp_buf, "[EZD]", PAGE_SIZE);
        }

        strlcat(state->pp_buf, "\n", PAGE_SIZE);

        /* second pass - output for each on a separate line */
        p = (struct partition *) (0x1be + data);
        for (slot = 1 ; slot <= 4 ; slot++, p++) {
                unsigned char id = SYS_IND(p);
                int n;

                if (!nr_sects(p))
                        continue;

                for (n = 0; subtypes[n].parse && id != subtypes[n].id; n++)
                        ;

                if (!subtypes[n].parse)
                        continue;
                subtypes[n].parse(state, start_sect(p) * sector_size,
                                  nr_sects(p) * sector_size, slot);
        }
        put_dev_sector(sect);
        return 1;
}