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 u64 io_size = hfsplus_min_io_size(sb); 52 loff_t start = (loff_t)sector << HFSPLUS_SECTOR_SHIFT; 53 int offset = start & (io_size - 1); 54 55 if ((opf & REQ_OP_MASK) != REQ_OP_WRITE && data) 56 *data = (u8 *)buf + offset; 57 58 /* 59 * Align sector to hardware sector size and find offset. We assume that 60 * io_size is a power of two, which _should_ be true. 61 */ 62 sector &= ~((io_size >> HFSPLUS_SECTOR_SHIFT) - 1); 63 return bdev_rw_virt(sb->s_bdev, sector, buf, io_size, opf); 64 } 65 66 static int hfsplus_read_mdb(void *bufptr, struct hfsplus_wd *wd) 67 { 68 u32 extent; 69 u16 attrib; 70 __be16 sig; 71 72 sig = *(__be16 *)(bufptr + HFSP_WRAPOFF_EMBEDSIG); 73 if (sig != cpu_to_be16(HFSPLUS_VOLHEAD_SIG) && 74 sig != cpu_to_be16(HFSPLUS_VOLHEAD_SIGX)) 75 return 0; 76 77 attrib = be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ATTRIB)); 78 if (!(attrib & HFSP_WRAP_ATTRIB_SLOCK) || 79 !(attrib & HFSP_WRAP_ATTRIB_SPARED)) 80 return 0; 81 82 wd->ablk_size = 83 be32_to_cpu(*(__be32 *)(bufptr + HFSP_WRAPOFF_ABLKSIZE)); 84 if (wd->ablk_size < HFSPLUS_SECTOR_SIZE) 85 return 0; 86 if (wd->ablk_size % HFSPLUS_SECTOR_SIZE) 87 return 0; 88 wd->ablk_start = 89 be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ABLKSTART)); 90 91 extent = get_unaligned_be32(bufptr + HFSP_WRAPOFF_EMBEDEXT); 92 wd->embed_start = (extent >> 16) & 0xFFFF; 93 wd->embed_count = extent & 0xFFFF; 94 95 return 1; 96 } 97 98 static int hfsplus_get_last_session(struct super_block *sb, 99 sector_t *start, sector_t *size) 100 { 101 struct cdrom_device_info *cdi = disk_to_cdi(sb->s_bdev->bd_disk); 102 103 /* default values */ 104 *start = 0; 105 *size = bdev_nr_sectors(sb->s_bdev); 106 107 if (HFSPLUS_SB(sb)->session >= 0) { 108 struct cdrom_tocentry te; 109 110 if (!cdi) 111 return -EINVAL; 112 113 te.cdte_track = HFSPLUS_SB(sb)->session; 114 te.cdte_format = CDROM_LBA; 115 if (cdrom_read_tocentry(cdi, &te) || 116 (te.cdte_ctrl & CDROM_DATA_TRACK) != 4) { 117 pr_err("invalid session number or type of track\n"); 118 return -EINVAL; 119 } 120 *start = (sector_t)te.cdte_addr.lba << 2; 121 } else if (cdi) { 122 struct cdrom_multisession ms_info; 123 124 ms_info.addr_format = CDROM_LBA; 125 if (cdrom_multisession(cdi, &ms_info) == 0 && ms_info.xa_flag) 126 *start = (sector_t)ms_info.addr.lba << 2; 127 } 128 129 return 0; 130 } 131 132 /* Find the volume header and fill in some minimum bits in superblock */ 133 /* Takes in super block, returns true if good data read */ 134 int hfsplus_read_wrapper(struct super_block *sb) 135 { 136 struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb); 137 struct hfsplus_wd wd; 138 sector_t part_start, part_size; 139 u32 blocksize; 140 int error = 0; 141 142 error = -EINVAL; 143 blocksize = sb_min_blocksize(sb, HFSPLUS_SECTOR_SIZE); 144 if (!blocksize) 145 goto out; 146 147 sbi->min_io_size = blocksize; 148 149 if (hfsplus_get_last_session(sb, &part_start, &part_size)) 150 goto out; 151 152 error = -ENOMEM; 153 sbi->s_vhdr_buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL); 154 if (!sbi->s_vhdr_buf) 155 goto out; 156 sbi->s_backup_vhdr_buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL); 157 if (!sbi->s_backup_vhdr_buf) 158 goto out_free_vhdr; 159 160 reread: 161 error = hfsplus_submit_bio(sb, part_start + HFSPLUS_VOLHEAD_SECTOR, 162 sbi->s_vhdr_buf, (void **)&sbi->s_vhdr, 163 REQ_OP_READ); 164 if (error) 165 goto out_free_backup_vhdr; 166 167 error = -EINVAL; 168 switch (sbi->s_vhdr->signature) { 169 case cpu_to_be16(HFSPLUS_VOLHEAD_SIGX): 170 set_bit(HFSPLUS_SB_HFSX, &sbi->flags); 171 fallthrough; 172 case cpu_to_be16(HFSPLUS_VOLHEAD_SIG): 173 break; 174 case cpu_to_be16(HFSP_WRAP_MAGIC): 175 if (!hfsplus_read_mdb(sbi->s_vhdr, &wd)) 176 goto out_free_backup_vhdr; 177 wd.ablk_size >>= HFSPLUS_SECTOR_SHIFT; 178 part_start += (sector_t)wd.ablk_start + 179 (sector_t)wd.embed_start * wd.ablk_size; 180 part_size = (sector_t)wd.embed_count * wd.ablk_size; 181 goto reread; 182 default: 183 /* 184 * Check for a partition block. 185 * 186 * (should do this only for cdrom/loop though) 187 */ 188 if (hfs_part_find(sb, &part_start, &part_size)) 189 goto out_free_backup_vhdr; 190 goto reread; 191 } 192 193 error = hfsplus_submit_bio(sb, part_start + part_size - 2, 194 sbi->s_backup_vhdr_buf, 195 (void **)&sbi->s_backup_vhdr, REQ_OP_READ); 196 if (error) 197 goto out_free_backup_vhdr; 198 199 error = -EINVAL; 200 if (sbi->s_backup_vhdr->signature != sbi->s_vhdr->signature) { 201 pr_warn("invalid secondary volume header\n"); 202 goto out_free_backup_vhdr; 203 } 204 205 blocksize = be32_to_cpu(sbi->s_vhdr->blocksize); 206 207 /* 208 * Block size must be at least as large as a sector and a multiple of 2. 209 */ 210 if (blocksize < HFSPLUS_SECTOR_SIZE || ((blocksize - 1) & blocksize)) 211 goto out_free_backup_vhdr; 212 sbi->alloc_blksz = blocksize; 213 sbi->alloc_blksz_shift = ilog2(blocksize); 214 blocksize = min_t(u32, sbi->alloc_blksz, PAGE_SIZE); 215 216 /* 217 * Align block size to block offset. 218 */ 219 while (part_start & ((blocksize >> HFSPLUS_SECTOR_SHIFT) - 1)) 220 blocksize >>= 1; 221 222 if (sb_set_blocksize(sb, blocksize) != blocksize) { 223 pr_err("unable to set blocksize to %u!\n", blocksize); 224 goto out_free_backup_vhdr; 225 } 226 227 sbi->blockoffset = 228 part_start >> (sb->s_blocksize_bits - HFSPLUS_SECTOR_SHIFT); 229 sbi->part_start = part_start; 230 sbi->sect_count = part_size; 231 sbi->fs_shift = sbi->alloc_blksz_shift - sb->s_blocksize_bits; 232 return 0; 233 234 out_free_backup_vhdr: 235 kfree(sbi->s_backup_vhdr_buf); 236 out_free_vhdr: 237 kfree(sbi->s_vhdr_buf); 238 out: 239 return error; 240 } 241