fs/hfsplus/wrapper.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  *  linux/fs/hfsplus/wrapper.c
0004  *
0005  * Copyright (C) 2001
0006  * Brad Boyer (flar@allandria.com)
0007  * (C) 2003 Ardis Technologies <roman@ardistech.com>
0008  *
0009  * Handling of HFS wrappers around HFS+ volumes
0010  */
0011
0012 #include <linux/fs.h>
0013 #include <linux/blkdev.h>
0014 #include <linux/cdrom.h>
0015 #include <asm/unaligned.h>
0016
0017 #include "hfsplus_fs.h"
0018 #include "hfsplus_raw.h"
0019
0020 struct hfsplus_wd {
0021     u32 ablk_size;
0022     u16 ablk_start;
0023     u16 embed_start;
0024     u16 embed_count;
0025 };
0026
0027 /**
0028  * hfsplus_submit_bio - Perform block I/O
0029  * @sb: super block of volume for I/O
0030  * @sector: block to read or write, for blocks of HFSPLUS_SECTOR_SIZE bytes
0031  * @buf: buffer for I/O
0032  * @data: output pointer for location of requested data
0033  * @op: direction of I/O
0034  * @op_flags: request op flags
0035  *
0036  * The unit of I/O is hfsplus_min_io_size(sb), which may be bigger than
0037  * HFSPLUS_SECTOR_SIZE, and @buf must be sized accordingly. On reads
0038  * @data will return a pointer to the start of the requested sector,
0039  * which may not be the same location as @buf.
0040  *
0041  * If @sector is not aligned to the bdev logical block size it will
0042  * be rounded down. For writes this means that @buf should contain data
0043  * that starts at the rounded-down address. As long as the data was
0044  * read using hfsplus_submit_bio() and the same buffer is used things
0045  * will work correctly.
0046  */
0047 int hfsplus_submit_bio(struct super_block *sb, sector_t sector,
0048                void *buf, void **data, blk_opf_t opf)
0049 {
0050     const enum req_op op = opf & REQ_OP_MASK;
0051     struct bio *bio;
0052     int ret = 0;
0053     u64 io_size;
0054     loff_t start;
0055     int offset;
0056
0057     /*
0058      * Align sector to hardware sector size and find offset. We
0059      * assume that io_size is a power of two, which _should_
0060      * be true.
0061      */
0062     io_size = hfsplus_min_io_size(sb);
0063     start = (loff_t)sector << HFSPLUS_SECTOR_SHIFT;
0064     offset = start & (io_size - 1);
0065     sector &= ~((io_size >> HFSPLUS_SECTOR_SHIFT) - 1);
0066
0067     bio = bio_alloc(sb->s_bdev, 1, opf, GFP_NOIO);
0068     bio->bi_iter.bi_sector = sector;
0069
0070     if (op != REQ_OP_WRITE && data)
0071         *data = (u8 *)buf + offset;
0072
0073     while (io_size > 0) {
0074         unsigned int page_offset = offset_in_page(buf);
0075         unsigned int len = min_t(unsigned int, PAGE_SIZE - page_offset,
0076                      io_size);
0077
0078         ret = bio_add_page(bio, virt_to_page(buf), len, page_offset);
0079         if (ret != len) {
0080             ret = -EIO;
0081             goto out;
0082         }
0083         io_size -= len;
0084         buf = (u8 *)buf + len;
0085     }
0086
0087     ret = submit_bio_wait(bio);
0088 out:
0089     bio_put(bio);
0090     return ret < 0 ? ret : 0;
0091 }
0092
0093 static int hfsplus_read_mdb(void *bufptr, struct hfsplus_wd *wd)
0094 {
0095     u32 extent;
0096     u16 attrib;
0097     __be16 sig;
0098
0099     sig = *(__be16 *)(bufptr + HFSP_WRAPOFF_EMBEDSIG);
0100     if (sig != cpu_to_be16(HFSPLUS_VOLHEAD_SIG) &&
0101         sig != cpu_to_be16(HFSPLUS_VOLHEAD_SIGX))
0102         return 0;
0103
0104     attrib = be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ATTRIB));
0105     if (!(attrib & HFSP_WRAP_ATTRIB_SLOCK) ||
0106        !(attrib & HFSP_WRAP_ATTRIB_SPARED))
0107         return 0;
0108
0109     wd->ablk_size =
0110         be32_to_cpu(*(__be32 *)(bufptr + HFSP_WRAPOFF_ABLKSIZE));
0111     if (wd->ablk_size < HFSPLUS_SECTOR_SIZE)
0112         return 0;
0113     if (wd->ablk_size % HFSPLUS_SECTOR_SIZE)
0114         return 0;
0115     wd->ablk_start =
0116         be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ABLKSTART));
0117
0118     extent = get_unaligned_be32(bufptr + HFSP_WRAPOFF_EMBEDEXT);
0119     wd->embed_start = (extent >> 16) & 0xFFFF;
0120     wd->embed_count = extent & 0xFFFF;
0121
0122     return 1;
0123 }
0124
0125 static int hfsplus_get_last_session(struct super_block *sb,
0126                     sector_t *start, sector_t *size)
0127 {
0128     struct cdrom_device_info *cdi = disk_to_cdi(sb->s_bdev->bd_disk);
0129
0130     /* default values */
0131     *start = 0;
0132     *size = bdev_nr_sectors(sb->s_bdev);
0133
0134     if (HFSPLUS_SB(sb)->session >= 0) {
0135         struct cdrom_tocentry te;
0136
0137         if (!cdi)
0138             return -EINVAL;
0139
0140         te.cdte_track = HFSPLUS_SB(sb)->session;
0141         te.cdte_format = CDROM_LBA;
0142         if (cdrom_read_tocentry(cdi, &te) ||
0143             (te.cdte_ctrl & CDROM_DATA_TRACK) != 4) {
0144             pr_err("invalid session number or type of track\n");
0145             return -EINVAL;
0146         }
0147         *start = (sector_t)te.cdte_addr.lba << 2;
0148     } else if (cdi) {
0149         struct cdrom_multisession ms_info;
0150
0151         ms_info.addr_format = CDROM_LBA;
0152         if (cdrom_multisession(cdi, &ms_info) == 0 && ms_info.xa_flag)
0153             *start = (sector_t)ms_info.addr.lba << 2;
0154     }
0155
0156     return 0;
0157 }
0158
0159 /* Find the volume header and fill in some minimum bits in superblock */
0160 /* Takes in super block, returns true if good data read */
0161 int hfsplus_read_wrapper(struct super_block *sb)
0162 {
0163     struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
0164     struct hfsplus_wd wd;
0165     sector_t part_start, part_size;
0166     u32 blocksize;
0167     int error = 0;
0168
0169     error = -EINVAL;
0170     blocksize = sb_min_blocksize(sb, HFSPLUS_SECTOR_SIZE);
0171     if (!blocksize)
0172         goto out;
0173
0174     if (hfsplus_get_last_session(sb, &part_start, &part_size))
0175         goto out;
0176
0177     error = -ENOMEM;
0178     sbi->s_vhdr_buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL);
0179     if (!sbi->s_vhdr_buf)
0180         goto out;
0181     sbi->s_backup_vhdr_buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL);
0182     if (!sbi->s_backup_vhdr_buf)
0183         goto out_free_vhdr;
0184
0185 reread:
0186     error = hfsplus_submit_bio(sb, part_start + HFSPLUS_VOLHEAD_SECTOR,
0187                    sbi->s_vhdr_buf, (void **)&sbi->s_vhdr,
0188                    REQ_OP_READ);
0189     if (error)
0190         goto out_free_backup_vhdr;
0191
0192     error = -EINVAL;
0193     switch (sbi->s_vhdr->signature) {
0194     case cpu_to_be16(HFSPLUS_VOLHEAD_SIGX):
0195         set_bit(HFSPLUS_SB_HFSX, &sbi->flags);
0196         fallthrough;
0197     case cpu_to_be16(HFSPLUS_VOLHEAD_SIG):
0198         break;
0199     case cpu_to_be16(HFSP_WRAP_MAGIC):
0200         if (!hfsplus_read_mdb(sbi->s_vhdr, &wd))
0201             goto out_free_backup_vhdr;
0202         wd.ablk_size >>= HFSPLUS_SECTOR_SHIFT;
0203         part_start += (sector_t)wd.ablk_start +
0204                    (sector_t)wd.embed_start * wd.ablk_size;
0205         part_size = (sector_t)wd.embed_count * wd.ablk_size;
0206         goto reread;
0207     default:
0208         /*
0209          * Check for a partition block.
0210          *
0211          * (should do this only for cdrom/loop though)
0212          */
0213         if (hfs_part_find(sb, &part_start, &part_size))
0214             goto out_free_backup_vhdr;
0215         goto reread;
0216     }
0217
0218     error = hfsplus_submit_bio(sb, part_start + part_size - 2,
0219                    sbi->s_backup_vhdr_buf,
0220                    (void **)&sbi->s_backup_vhdr, REQ_OP_READ);
0221     if (error)
0222         goto out_free_backup_vhdr;
0223
0224     error = -EINVAL;
0225     if (sbi->s_backup_vhdr->signature != sbi->s_vhdr->signature) {
0226         pr_warn("invalid secondary volume header\n");
0227         goto out_free_backup_vhdr;
0228     }
0229
0230     blocksize = be32_to_cpu(sbi->s_vhdr->blocksize);
0231
0232     /*
0233      * Block size must be at least as large as a sector and a multiple of 2.
0234      */
0235     if (blocksize < HFSPLUS_SECTOR_SIZE || ((blocksize - 1) & blocksize))
0236         goto out_free_backup_vhdr;
0237     sbi->alloc_blksz = blocksize;
0238     sbi->alloc_blksz_shift = ilog2(blocksize);
0239     blocksize = min_t(u32, sbi->alloc_blksz, PAGE_SIZE);
0240
0241     /*
0242      * Align block size to block offset.
0243      */
0244     while (part_start & ((blocksize >> HFSPLUS_SECTOR_SHIFT) - 1))
0245         blocksize >>= 1;
0246
0247     if (sb_set_blocksize(sb, blocksize) != blocksize) {
0248         pr_err("unable to set blocksize to %u!\n", blocksize);
0249         goto out_free_backup_vhdr;
0250     }
0251
0252     sbi->blockoffset =
0253         part_start >> (sb->s_blocksize_bits - HFSPLUS_SECTOR_SHIFT);
0254     sbi->part_start = part_start;
0255     sbi->sect_count = part_size;
0256     sbi->fs_shift = sbi->alloc_blksz_shift - sb->s_blocksize_bits;
0257     return 0;
0258
0259 out_free_backup_vhdr:
0260     kfree(sbi->s_backup_vhdr_buf);
0261 out_free_vhdr:
0262     kfree(sbi->s_vhdr_buf);
0263 out:
0264     return error;
0265 }