block/partitions/amiga.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  fs/partitions/amiga.c
   4  *
   5  *  Code extracted from drivers/block/genhd.c
   6  *
   7  *  Copyright (C) 1991-1998  Linus Torvalds
   8  *  Re-organised Feb 1998 Russell King
   9  */
  10
  11 #define pr_fmt(fmt) fmt
  12
  13 #include <linux/types.h>
  14 #include <linux/mm_types.h>
  15 #include <linux/overflow.h>
  16 #include <linux/affs_hardblocks.h>
  17
  18 #include "check.h"
  19
  20 /* magic offsets in partition DosEnvVec */
  21 #define NR_HD   3
  22 #define NR_SECT 5
  23 #define LO_CYL  9
  24 #define HI_CYL  10
  25
  26 static __inline__ u32
  27 checksum_block(__be32 *m, int size)
  28 {
  29         u32 sum = 0;
  30
  31         while (size--)
  32                 sum += be32_to_cpu(*m++);
  33         return sum;
  34 }
  35
  36 int amiga_partition(struct parsed_partitions *state)
  37 {
  38         Sector sect;
  39         unsigned char *data;
  40         struct RigidDiskBlock *rdb;
  41         struct PartitionBlock *pb;
  42         u64 start_sect, nr_sects;
  43         sector_t blk, end_sect;
  44         u32 cylblk;             /* rdb_CylBlocks = nr_heads*sect_per_track */
  45         u32 nr_hd, nr_sect, lo_cyl, hi_cyl;
  46         int part, res = 0;
  47         unsigned int blksize = 1;       /* Multiplier for disk block size */
  48         int slot = 1;
  49         char b[BDEVNAME_SIZE];
  50
  51         for (blk = 0; ; blk++, put_dev_sector(sect)) {
  52                 if (blk == RDB_ALLOCATION_LIMIT)
  53                         goto rdb_done;
  54                 data = read_part_sector(state, blk, &sect);
  55                 if (!data) {
  56                         pr_err("Dev %s: unable to read RDB block %llu\n",
  57                                bdevname(state->bdev, b), blk);
  58                         res = -1;
  59                         goto rdb_done;
  60                 }
  61                 if (*(__be32 *)data != cpu_to_be32(IDNAME_RIGIDDISK))
  62                         continue;
  63
  64                 rdb = (struct RigidDiskBlock *)data;
  65                 if (checksum_block((__be32 *)data, be32_to_cpu(rdb->rdb_SummedLongs) & 0x7F) == 0)
  66                         break;
  67                 /* Try again with 0xdc..0xdf zeroed, Windows might have
  68                  * trashed it.
  69                  */
  70                 *(__be32 *)(data+0xdc) = 0;
  71                 if (checksum_block((__be32 *)data,
  72                                 be32_to_cpu(rdb->rdb_SummedLongs) & 0x7F)==0) {
  73                         pr_err("Trashed word at 0xd0 in block %llu ignored in checksum calculation\n",
  74                                blk);
  75                         break;
  76                 }
  77
  78                 pr_err("Dev %s: RDB in block %llu has bad checksum\n",
  79                        bdevname(state->bdev, b), blk);
  80         }
  81
  82         /* blksize is blocks per 512 byte standard block */
  83         blksize = be32_to_cpu( rdb->rdb_BlockBytes ) / 512;
  84
  85         {
  86                 char tmp[7 + 10 + 1 + 1];
  87
  88                 /* Be more informative */
  89                 snprintf(tmp, sizeof(tmp), " RDSK (%d)", blksize * 512);
  90                 strlcat(state->pp_buf, tmp, PAGE_SIZE);
  91         }
  92         blk = be32_to_cpu(rdb->rdb_PartitionList);
  93         put_dev_sector(sect);
  94         for (part = 1; (s32) blk>0 && part<=16; part++, put_dev_sector(sect)) {
  95                 /* Read in terms partition table understands */
  96                 if (check_mul_overflow(blk, (sector_t) blksize, &blk)) {
  97                         pr_err("Dev %s: overflow calculating partition block %llu! Skipping partitions %u and beyond\n",
  98                                 bdevname(state->bdev, b), blk, part);
  99                         break;
 100                 }
 101                 data = read_part_sector(state, blk, &sect);
 102                 if (!data) {
 103                         pr_err("Dev %s: unable to read partition block %llu\n",
 104                                bdevname(state->bdev, b), blk);
 105                         res = -1;
 106                         goto rdb_done;
 107                 }
 108                 pb  = (struct PartitionBlock *)data;
 109                 blk = be32_to_cpu(pb->pb_Next);
 110                 if (pb->pb_ID != cpu_to_be32(IDNAME_PARTITION))
 111                         continue;
 112                 if (checksum_block((__be32 *)pb, be32_to_cpu(pb->pb_SummedLongs) & 0x7F) != 0 )
 113                         continue;
 114
 115                 /* RDB gives us more than enough rope to hang ourselves with,
 116                  * many times over (2^128 bytes if all fields max out).
 117                  * Some careful checks are in order, so check for potential
 118                  * overflows.
 119                  * We are multiplying four 32 bit numbers to one sector_t!
 120                  */
 121
 122                 nr_hd   = be32_to_cpu(pb->pb_Environment[NR_HD]);
 123                 nr_sect = be32_to_cpu(pb->pb_Environment[NR_SECT]);
 124
 125                 /* CylBlocks is total number of blocks per cylinder */
 126                 if (check_mul_overflow(nr_hd, nr_sect, &cylblk)) {
 127                         pr_err("Dev %s: heads*sects %u overflows u32, skipping partition!\n",
 128                                 bdevname(state->bdev, b), cylblk);
 129                         continue;
 130                 }
 131
 132                 /* check for consistency with RDB defined CylBlocks */
 133                 if (cylblk > be32_to_cpu(rdb->rdb_CylBlocks)) {
 134                         pr_warn("Dev %s: cylblk %u > rdb_CylBlocks %u!\n",
 135                                 bdevname(state->bdev, b), cylblk,
 136                                 be32_to_cpu(rdb->rdb_CylBlocks));
 137                 }
 138
 139                 /* RDB allows for variable logical block size -
 140                  * normalize to 512 byte blocks and check result.
 141                  */
 142
 143                 if (check_mul_overflow(cylblk, blksize, &cylblk)) {
 144                         pr_err("Dev %s: partition %u bytes per cyl. overflows u32, skipping partition!\n",
 145                                 bdevname(state->bdev, b), part);
 146                         continue;
 147                 }
 148
 149                 /* Calculate partition start and end. Limit of 32 bit on cylblk
 150                  * guarantees no overflow occurs if LBD support is enabled.
 151                  */
 152
 153                 lo_cyl = be32_to_cpu(pb->pb_Environment[LO_CYL]);
 154                 start_sect = ((u64) lo_cyl * cylblk);
 155
 156                 hi_cyl = be32_to_cpu(pb->pb_Environment[HI_CYL]);
 157                 nr_sects = (((u64) hi_cyl - lo_cyl + 1) * cylblk);
 158
 159                 if (!nr_sects)
 160                         continue;
 161
 162                 /* Warn user if partition end overflows u32 (AmigaDOS limit) */
 163
 164                 if ((start_sect + nr_sects) > UINT_MAX) {
 165                         pr_warn("Dev %s: partition %u (%llu-%llu) needs 64 bit device support!\n",
 166                                 bdevname(state->bdev, b), part,
 167                                 start_sect, start_sect + nr_sects);
 168                 }
 169
 170                 if (check_add_overflow(start_sect, nr_sects, &end_sect)) {
 171                         pr_err("Dev %s: partition %u (%llu-%llu) needs LBD device support, skipping partition!\n",
 172                                 bdevname(state->bdev, b), part,
 173                                 start_sect, end_sect);
 174                         continue;
 175                 }
 176
 177                 /* Tell Kernel about it */
 178
 179                 put_partition(state,slot++,start_sect,nr_sects);
 180                 {
 181                         /* Be even more informative to aid mounting */
 182                         char dostype[4];
 183                         char tmp[42];
 184
 185                         __be32 *dt = (__be32 *)dostype;
 186                         *dt = pb->pb_Environment[16];
 187                         if (dostype[3] < ' ')
 188                                 snprintf(tmp, sizeof(tmp), " (%c%c%c^%c)",
 189                                         dostype[0], dostype[1],
 190                                         dostype[2], dostype[3] + '@' );
 191                         else
 192                                 snprintf(tmp, sizeof(tmp), " (%c%c%c%c)",
 193                                         dostype[0], dostype[1],
 194                                         dostype[2], dostype[3]);
 195                         strlcat(state->pp_buf, tmp, PAGE_SIZE);
 196                         snprintf(tmp, sizeof(tmp), "(res %d spb %d)",
 197                                 be32_to_cpu(pb->pb_Environment[6]),
 198                                 be32_to_cpu(pb->pb_Environment[4]));
 199                         strlcat(state->pp_buf, tmp, PAGE_SIZE);
 200                 }
 201                 res = 1;
 202         }
 203         strlcat(state->pp_buf, "\n", PAGE_SIZE);
 204
 205 rdb_done:
 206         return res;
 207 }