fs/hfsplus/wrapper.c

   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/genhd.h>
  16 #include <asm/unaligned.h>
  17
  18 #include "hfsplus_fs.h"
  19 #include "hfsplus_raw.h"
  20
  21 struct hfsplus_wd {
  22         u32 ablk_size;
  23         u16 ablk_start;
  24         u16 embed_start;
  25         u16 embed_count;
  26 };
  27
  28 /**
  29  * hfsplus_submit_bio - Perform block I/O
  30  * @sb: super block of volume for I/O
  31  * @sector: block to read or write, for blocks of HFSPLUS_SECTOR_SIZE bytes
  32  * @buf: buffer for I/O
  33  * @data: output pointer for location of requested data
  34  * @op: direction of I/O
  35  * @op_flags: request op flags
  36  *
  37  * The unit of I/O is hfsplus_min_io_size(sb), which may be bigger than
  38  * HFSPLUS_SECTOR_SIZE, and @buf must be sized accordingly. On reads
  39  * @data will return a pointer to the start of the requested sector,
  40  * which may not be the same location as @buf.
  41  *
  42  * If @sector is not aligned to the bdev logical block size it will
  43  * be rounded down. For writes this means that @buf should contain data
  44  * that starts at the rounded-down address. As long as the data was
  45  * read using hfsplus_submit_bio() and the same buffer is used things
  46  * will work correctly.
  47  */
  48 int hfsplus_submit_bio(struct super_block *sb, sector_t sector,
  49                        void *buf, void **data, int op, int op_flags)
  50 {
  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(GFP_NOIO, 1);
  68         bio->bi_iter.bi_sector = sector;
  69         bio_set_dev(bio, sb->s_bdev);
  70         bio_set_op_attrs(bio, op, op_flags);
  71
  72         if (op != WRITE && data)
  73                 *data = (u8 *)buf + offset;
  74
  75         while (io_size > 0) {
  76                 unsigned int page_offset = offset_in_page(buf);
  77                 unsigned int len = min_t(unsigned int, PAGE_SIZE - page_offset,
  78                                          io_size);
  79
  80                 ret = bio_add_page(bio, virt_to_page(buf), len, page_offset);
  81                 if (ret != len) {
  82                         ret = -EIO;
  83                         goto out;
  84                 }
  85                 io_size -= len;
  86                 buf = (u8 *)buf + len;
  87         }
  88
  89         ret = submit_bio_wait(bio);
  90 out:
  91         bio_put(bio);
  92         return ret < 0 ? ret : 0;
  93 }
  94
  95 static int hfsplus_read_mdb(void *bufptr, struct hfsplus_wd *wd)
  96 {
  97         u32 extent;
  98         u16 attrib;
  99         __be16 sig;
 100
 101         sig = *(__be16 *)(bufptr + HFSP_WRAPOFF_EMBEDSIG);
 102         if (sig != cpu_to_be16(HFSPLUS_VOLHEAD_SIG) &&
 103             sig != cpu_to_be16(HFSPLUS_VOLHEAD_SIGX))
 104                 return 0;
 105
 106         attrib = be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ATTRIB));
 107         if (!(attrib & HFSP_WRAP_ATTRIB_SLOCK) ||
 108            !(attrib & HFSP_WRAP_ATTRIB_SPARED))
 109                 return 0;
 110
 111         wd->ablk_size =
 112                 be32_to_cpu(*(__be32 *)(bufptr + HFSP_WRAPOFF_ABLKSIZE));
 113         if (wd->ablk_size < HFSPLUS_SECTOR_SIZE)
 114                 return 0;
 115         if (wd->ablk_size % HFSPLUS_SECTOR_SIZE)
 116                 return 0;
 117         wd->ablk_start =
 118                 be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ABLKSTART));
 119
 120         extent = get_unaligned_be32(bufptr + HFSP_WRAPOFF_EMBEDEXT);
 121         wd->embed_start = (extent >> 16) & 0xFFFF;
 122         wd->embed_count = extent & 0xFFFF;
 123
 124         return 1;
 125 }
 126
 127 static int hfsplus_get_last_session(struct super_block *sb,
 128                                     sector_t *start, sector_t *size)
 129 {
 130         struct cdrom_device_info *cdi = disk_to_cdi(sb->s_bdev->bd_disk);
 131
 132         /* default values */
 133         *start = 0;
 134         *size = i_size_read(sb->s_bdev->bd_inode) >> 9;
 135
 136         if (HFSPLUS_SB(sb)->session >= 0) {
 137                 struct cdrom_tocentry te;
 138
 139                 if (!cdi)
 140                         return -EINVAL;
 141
 142                 te.cdte_track = HFSPLUS_SB(sb)->session;
 143                 te.cdte_format = CDROM_LBA;
 144                 if (cdrom_read_tocentry(cdi, &te) ||
 145                     (te.cdte_ctrl & CDROM_DATA_TRACK) != 4) {
 146                         pr_err("invalid session number or type of track\n");
 147                         return -EINVAL;
 148                 }
 149                 *start = (sector_t)te.cdte_addr.lba << 2;
 150         } else if (cdi) {
 151                 struct cdrom_multisession ms_info;
 152
 153                 ms_info.addr_format = CDROM_LBA;
 154                 if (cdrom_multisession(cdi, &ms_info) == 0 && ms_info.xa_flag)
 155                         *start = (sector_t)ms_info.addr.lba << 2;
 156         }
 157
 158         return 0;
 159 }
 160
 161 /* Find the volume header and fill in some minimum bits in superblock */
 162 /* Takes in super block, returns true if good data read */
 163 int hfsplus_read_wrapper(struct super_block *sb)
 164 {
 165         struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
 166         struct hfsplus_wd wd;
 167         sector_t part_start, part_size;
 168         u32 blocksize;
 169         int error = 0;
 170
 171         error = -EINVAL;
 172         blocksize = sb_min_blocksize(sb, HFSPLUS_SECTOR_SIZE);
 173         if (!blocksize)
 174                 goto out;
 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, 0);
 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                                    0);
 224         if (error)
 225                 goto out_free_backup_vhdr;
 226
 227         error = -EINVAL;
 228         if (sbi->s_backup_vhdr->signature != sbi->s_vhdr->signature) {
 229                 pr_warn("invalid secondary volume header\n");
 230                 goto out_free_backup_vhdr;
 231         }
 232
 233         blocksize = be32_to_cpu(sbi->s_vhdr->blocksize);
 234
 235         /*
 236          * Block size must be at least as large as a sector and a multiple of 2.
 237          */
 238         if (blocksize < HFSPLUS_SECTOR_SIZE || ((blocksize - 1) & blocksize))
 239                 goto out_free_backup_vhdr;
 240         sbi->alloc_blksz = blocksize;
 241         sbi->alloc_blksz_shift = ilog2(blocksize);
 242         blocksize = min_t(u32, sbi->alloc_blksz, PAGE_SIZE);
 243
 244         /*
 245          * Align block size to block offset.
 246          */
 247         while (part_start & ((blocksize >> HFSPLUS_SECTOR_SHIFT) - 1))
 248                 blocksize >>= 1;
 249
 250         if (sb_set_blocksize(sb, blocksize) != blocksize) {
 251                 pr_err("unable to set blocksize to %u!\n", blocksize);
 252                 goto out_free_backup_vhdr;
 253         }
 254
 255         sbi->blockoffset =
 256                 part_start >> (sb->s_blocksize_bits - HFSPLUS_SECTOR_SHIFT);
 257         sbi->part_start = part_start;
 258         sbi->sect_count = part_size;
 259         sbi->fs_shift = sbi->alloc_blksz_shift - sb->s_blocksize_bits;
 260         return 0;
 261
 262 out_free_backup_vhdr:
 263         kfree(sbi->s_backup_vhdr_buf);
 264 out_free_vhdr:
 265         kfree(sbi->s_vhdr_buf);
 266 out:
 267         return error;
 268 }