xref: /openbmc/linux/block/partitions/amiga.c (revision 7eb1e476)
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, &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 }
207