1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * linux/fs/hfsplus/wrapper.c
4 *
5 * Copyright (C) 2001
6 * Brad Boyer (flar@allandria.com)
7 * (C) 2003 Ardis Technologies <roman@ardistech.com>
8 *
9 * Handling of HFS wrappers around HFS+ volumes
10 */
11
12 #include <linux/fs.h>
13 #include <linux/blkdev.h>
14 #include <linux/cdrom.h>
15 #include <asm/unaligned.h>
16
17 #include "hfsplus_fs.h"
18 #include "hfsplus_raw.h"
19
20 struct hfsplus_wd {
21 u32 ablk_size;
22 u16 ablk_start;
23 u16 embed_start;
24 u16 embed_count;
25 };
26
27 /**
28 * hfsplus_submit_bio - Perform block I/O
29 * @sb: super block of volume for I/O
30 * @sector: block to read or write, for blocks of HFSPLUS_SECTOR_SIZE bytes
31 * @buf: buffer for I/O
32 * @data: output pointer for location of requested data
33 * @op: direction of I/O
34 * @op_flags: request op flags
35 *
36 * The unit of I/O is hfsplus_min_io_size(sb), which may be bigger than
37 * HFSPLUS_SECTOR_SIZE, and @buf must be sized accordingly. On reads
38 * @data will return a pointer to the start of the requested sector,
39 * which may not be the same location as @buf.
40 *
41 * If @sector is not aligned to the bdev logical block size it will
42 * be rounded down. For writes this means that @buf should contain data
43 * that starts at the rounded-down address. As long as the data was
44 * read using hfsplus_submit_bio() and the same buffer is used things
45 * will work correctly.
46 */
hfsplus_submit_bio(struct super_block * sb,sector_t sector,void * buf,void ** data,blk_opf_t opf)47 int hfsplus_submit_bio(struct super_block *sb, sector_t sector,
48 void *buf, void **data, blk_opf_t opf)
49 {
50 const enum req_op op = opf & REQ_OP_MASK;
51 struct bio *bio;
52 int ret = 0;
53 u64 io_size;
54 loff_t start;
55 int offset;
56
57 /*
58 * Align sector to hardware sector size and find offset. We
59 * assume that io_size is a power of two, which _should_
60 * be true.
61 */
62 io_size = hfsplus_min_io_size(sb);
63 start = (loff_t)sector << HFSPLUS_SECTOR_SHIFT;
64 offset = start & (io_size - 1);
65 sector &= ~((io_size >> HFSPLUS_SECTOR_SHIFT) - 1);
66
67 bio = bio_alloc(sb->s_bdev, 1, opf, GFP_NOIO);
68 bio->bi_iter.bi_sector = sector;
69
70 if (op != REQ_OP_WRITE && data)
71 *data = (u8 *)buf + offset;
72
73 while (io_size > 0) {
74 unsigned int page_offset = offset_in_page(buf);
75 unsigned int len = min_t(unsigned int, PAGE_SIZE - page_offset,
76 io_size);
77
78 ret = bio_add_page(bio, virt_to_page(buf), len, page_offset);
79 if (ret != len) {
80 ret = -EIO;
81 goto out;
82 }
83 io_size -= len;
84 buf = (u8 *)buf + len;
85 }
86
87 ret = submit_bio_wait(bio);
88 out:
89 bio_put(bio);
90 return ret < 0 ? ret : 0;
91 }
92
hfsplus_read_mdb(void * bufptr,struct hfsplus_wd * wd)93 static int hfsplus_read_mdb(void *bufptr, struct hfsplus_wd *wd)
94 {
95 u32 extent;
96 u16 attrib;
97 __be16 sig;
98
99 sig = *(__be16 *)(bufptr + HFSP_WRAPOFF_EMBEDSIG);
100 if (sig != cpu_to_be16(HFSPLUS_VOLHEAD_SIG) &&
101 sig != cpu_to_be16(HFSPLUS_VOLHEAD_SIGX))
102 return 0;
103
104 attrib = be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ATTRIB));
105 if (!(attrib & HFSP_WRAP_ATTRIB_SLOCK) ||
106 !(attrib & HFSP_WRAP_ATTRIB_SPARED))
107 return 0;
108
109 wd->ablk_size =
110 be32_to_cpu(*(__be32 *)(bufptr + HFSP_WRAPOFF_ABLKSIZE));
111 if (wd->ablk_size < HFSPLUS_SECTOR_SIZE)
112 return 0;
113 if (wd->ablk_size % HFSPLUS_SECTOR_SIZE)
114 return 0;
115 wd->ablk_start =
116 be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ABLKSTART));
117
118 extent = get_unaligned_be32(bufptr + HFSP_WRAPOFF_EMBEDEXT);
119 wd->embed_start = (extent >> 16) & 0xFFFF;
120 wd->embed_count = extent & 0xFFFF;
121
122 return 1;
123 }
124
hfsplus_get_last_session(struct super_block * sb,sector_t * start,sector_t * size)125 static int hfsplus_get_last_session(struct super_block *sb,
126 sector_t *start, sector_t *size)
127 {
128 struct cdrom_device_info *cdi = disk_to_cdi(sb->s_bdev->bd_disk);
129
130 /* default values */
131 *start = 0;
132 *size = bdev_nr_sectors(sb->s_bdev);
133
134 if (HFSPLUS_SB(sb)->session >= 0) {
135 struct cdrom_tocentry te;
136
137 if (!cdi)
138 return -EINVAL;
139
140 te.cdte_track = HFSPLUS_SB(sb)->session;
141 te.cdte_format = CDROM_LBA;
142 if (cdrom_read_tocentry(cdi, &te) ||
143 (te.cdte_ctrl & CDROM_DATA_TRACK) != 4) {
144 pr_err("invalid session number or type of track\n");
145 return -EINVAL;
146 }
147 *start = (sector_t)te.cdte_addr.lba << 2;
148 } else if (cdi) {
149 struct cdrom_multisession ms_info;
150
151 ms_info.addr_format = CDROM_LBA;
152 if (cdrom_multisession(cdi, &ms_info) == 0 && ms_info.xa_flag)
153 *start = (sector_t)ms_info.addr.lba << 2;
154 }
155
156 return 0;
157 }
158
159 /* Find the volume header and fill in some minimum bits in superblock */
160 /* Takes in super block, returns true if good data read */
hfsplus_read_wrapper(struct super_block * sb)161 int hfsplus_read_wrapper(struct super_block *sb)
162 {
163 struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
164 struct hfsplus_wd wd;
165 sector_t part_start, part_size;
166 u32 blocksize;
167 int error = 0;
168
169 error = -EINVAL;
170 blocksize = sb_min_blocksize(sb, HFSPLUS_SECTOR_SIZE);
171 if (!blocksize)
172 goto out;
173
174 sbi->min_io_size = blocksize;
175
176 if (hfsplus_get_last_session(sb, &part_start, &part_size))
177 goto out;
178
179 error = -ENOMEM;
180 sbi->s_vhdr_buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL);
181 if (!sbi->s_vhdr_buf)
182 goto out;
183 sbi->s_backup_vhdr_buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL);
184 if (!sbi->s_backup_vhdr_buf)
185 goto out_free_vhdr;
186
187 reread:
188 error = hfsplus_submit_bio(sb, part_start + HFSPLUS_VOLHEAD_SECTOR,
189 sbi->s_vhdr_buf, (void **)&sbi->s_vhdr,
190 REQ_OP_READ);
191 if (error)
192 goto out_free_backup_vhdr;
193
194 error = -EINVAL;
195 switch (sbi->s_vhdr->signature) {
196 case cpu_to_be16(HFSPLUS_VOLHEAD_SIGX):
197 set_bit(HFSPLUS_SB_HFSX, &sbi->flags);
198 fallthrough;
199 case cpu_to_be16(HFSPLUS_VOLHEAD_SIG):
200 break;
201 case cpu_to_be16(HFSP_WRAP_MAGIC):
202 if (!hfsplus_read_mdb(sbi->s_vhdr, &wd))
203 goto out_free_backup_vhdr;
204 wd.ablk_size >>= HFSPLUS_SECTOR_SHIFT;
205 part_start += (sector_t)wd.ablk_start +
206 (sector_t)wd.embed_start * wd.ablk_size;
207 part_size = (sector_t)wd.embed_count * wd.ablk_size;
208 goto reread;
209 default:
210 /*
211 * Check for a partition block.
212 *
213 * (should do this only for cdrom/loop though)
214 */
215 if (hfs_part_find(sb, &part_start, &part_size))
216 goto out_free_backup_vhdr;
217 goto reread;
218 }
219
220 error = hfsplus_submit_bio(sb, part_start + part_size - 2,
221 sbi->s_backup_vhdr_buf,
222 (void **)&sbi->s_backup_vhdr, REQ_OP_READ);
223 if (error)
224 goto out_free_backup_vhdr;
225
226 error = -EINVAL;
227 if (sbi->s_backup_vhdr->signature != sbi->s_vhdr->signature) {
228 pr_warn("invalid secondary volume header\n");
229 goto out_free_backup_vhdr;
230 }
231
232 blocksize = be32_to_cpu(sbi->s_vhdr->blocksize);
233
234 /*
235 * Block size must be at least as large as a sector and a multiple of 2.
236 */
237 if (blocksize < HFSPLUS_SECTOR_SIZE || ((blocksize - 1) & blocksize))
238 goto out_free_backup_vhdr;
239 sbi->alloc_blksz = blocksize;
240 sbi->alloc_blksz_shift = ilog2(blocksize);
241 blocksize = min_t(u32, sbi->alloc_blksz, PAGE_SIZE);
242
243 /*
244 * Align block size to block offset.
245 */
246 while (part_start & ((blocksize >> HFSPLUS_SECTOR_SHIFT) - 1))
247 blocksize >>= 1;
248
249 if (sb_set_blocksize(sb, blocksize) != blocksize) {
250 pr_err("unable to set blocksize to %u!\n", blocksize);
251 goto out_free_backup_vhdr;
252 }
253
254 sbi->blockoffset =
255 part_start >> (sb->s_blocksize_bits - HFSPLUS_SECTOR_SHIFT);
256 sbi->part_start = part_start;
257 sbi->sect_count = part_size;
258 sbi->fs_shift = sbi->alloc_blksz_shift - sb->s_blocksize_bits;
259 return 0;
260
261 out_free_backup_vhdr:
262 kfree(sbi->s_backup_vhdr_buf);
263 out_free_vhdr:
264 kfree(sbi->s_vhdr_buf);
265 out:
266 return error;
267 }
268