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, §); 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, §); 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 } 207