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/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         sbi->min_io_size = blocksize;
 176
 177         if (hfsplus_get_last_session(sb, &part_start, &part_size))
 178                 goto out;
 179
 180         error = -ENOMEM;
 181         sbi->s_vhdr_buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL);
 182         if (!sbi->s_vhdr_buf)
 183                 goto out;
 184         sbi->s_backup_vhdr_buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL);
 185         if (!sbi->s_backup_vhdr_buf)
 186                 goto out_free_vhdr;
 187
 188 reread:
 189         error = hfsplus_submit_bio(sb, part_start + HFSPLUS_VOLHEAD_SECTOR,
 190                                    sbi->s_vhdr_buf, (void **)&sbi->s_vhdr,
 191                                    REQ_OP_READ);
 192         if (error)
 193                 goto out_free_backup_vhdr;
 194
 195         error = -EINVAL;
 196         switch (sbi->s_vhdr->signature) {
 197         case cpu_to_be16(HFSPLUS_VOLHEAD_SIGX):
 198                 set_bit(HFSPLUS_SB_HFSX, &sbi->flags);
 199                 fallthrough;
 200         case cpu_to_be16(HFSPLUS_VOLHEAD_SIG):
 201                 break;
 202         case cpu_to_be16(HFSP_WRAP_MAGIC):
 203                 if (!hfsplus_read_mdb(sbi->s_vhdr, &wd))
 204                         goto out_free_backup_vhdr;
 205                 wd.ablk_size >>= HFSPLUS_SECTOR_SHIFT;
 206                 part_start += (sector_t)wd.ablk_start +
 207                                (sector_t)wd.embed_start * wd.ablk_size;
 208                 part_size = (sector_t)wd.embed_count * wd.ablk_size;
 209                 goto reread;
 210         default:
 211                 /*
 212                  * Check for a partition block.
 213                  *
 214                  * (should do this only for cdrom/loop though)
 215                  */
 216                 if (hfs_part_find(sb, &part_start, &part_size))
 217                         goto out_free_backup_vhdr;
 218                 goto reread;
 219         }
 220
 221         error = hfsplus_submit_bio(sb, part_start + part_size - 2,
 222                                    sbi->s_backup_vhdr_buf,
 223                                    (void **)&sbi->s_backup_vhdr, REQ_OP_READ);
 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 }