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 26static __inline__ u32 27checksum_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 36int 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, §); 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, §); 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 205rdb_done: 206 return res; 207} 208