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 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
205 rdb_done:
206 return res;
207 }
208