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