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