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
 20struct 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 */
 48int 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
 66static 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
 98static 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 */
134int 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
160reread:
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
234out_free_backup_vhdr:
235	kfree(sbi->s_backup_vhdr_buf);
236out_free_vhdr:
237	kfree(sbi->s_vhdr_buf);
238out:
239	return error;
240}