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
checksum_block(__be32 * m,int size)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
amiga_partition(struct parsed_partitions * state)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