cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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part_tbl.c (4344B)

      1/*
      2 * linux/fs/hfsplus/part_tbl.c
      3 *
      4 * Copyright (C) 1996-1997  Paul H. Hargrove
      5 * This file may be distributed under the terms of
      6 * the GNU General Public License.
      7 *
      8 * Original code to handle the new style Mac partition table based on
      9 * a patch contributed by Holger Schemel (aeglos@valinor.owl.de).
     10 *
     11 * In function preconditions the term "valid" applied to a pointer to
     12 * a structure means that the pointer is non-NULL and the structure it
     13 * points to has all fields initialized to consistent values.
     14 *
     15 */
     16
     17#include <linux/slab.h>
     18#include "hfsplus_fs.h"
     19
     20/* offsets to various blocks */
     21#define HFS_DD_BLK		0 /* Driver Descriptor block */
     22#define HFS_PMAP_BLK		1 /* First block of partition map */
     23#define HFS_MDB_BLK		2 /* Block (w/i partition) of MDB */
     24
     25/* magic numbers for various disk blocks */
     26#define HFS_DRVR_DESC_MAGIC	0x4552 /* "ER": driver descriptor map */
     27#define HFS_OLD_PMAP_MAGIC	0x5453 /* "TS": old-type partition map */
     28#define HFS_NEW_PMAP_MAGIC	0x504D /* "PM": new-type partition map */
     29#define HFS_SUPER_MAGIC		0x4244 /* "BD": HFS MDB (super block) */
     30#define HFS_MFS_SUPER_MAGIC	0xD2D7 /* MFS MDB (super block) */
     31
     32/*
     33 * The new style Mac partition map
     34 *
     35 * For each partition on the media there is a physical block (512-byte
     36 * block) containing one of these structures.  These blocks are
     37 * contiguous starting at block 1.
     38 */
     39struct new_pmap {
     40	__be16	pmSig;		/* signature */
     41	__be16	reSigPad;	/* padding */
     42	__be32	pmMapBlkCnt;	/* partition blocks count */
     43	__be32	pmPyPartStart;	/* physical block start of partition */
     44	__be32	pmPartBlkCnt;	/* physical block count of partition */
     45	u8	pmPartName[32];	/* (null terminated?) string
     46				   giving the name of this
     47				   partition */
     48	u8	pmPartType[32];	/* (null terminated?) string
     49				   giving the type of this
     50				   partition */
     51	/* a bunch more stuff we don't need */
     52} __packed;
     53
     54/*
     55 * The old style Mac partition map
     56 *
     57 * The partition map consists for a 2-byte signature followed by an
     58 * array of these structures.  The map is terminated with an all-zero
     59 * one of these.
     60 */
     61struct old_pmap {
     62	__be16		pdSig;	/* Signature bytes */
     63	struct old_pmap_entry {
     64		__be32	pdStart;
     65		__be32	pdSize;
     66		__be32	pdFSID;
     67	}	pdEntry[42];
     68} __packed;
     69
     70static int hfs_parse_old_pmap(struct super_block *sb, struct old_pmap *pm,
     71		sector_t *part_start, sector_t *part_size)
     72{
     73	struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
     74	int i;
     75
     76	for (i = 0; i < 42; i++) {
     77		struct old_pmap_entry *p = &pm->pdEntry[i];
     78
     79		if (p->pdStart && p->pdSize &&
     80		    p->pdFSID == cpu_to_be32(0x54465331)/*"TFS1"*/ &&
     81		    (sbi->part < 0 || sbi->part == i)) {
     82			*part_start += be32_to_cpu(p->pdStart);
     83			*part_size = be32_to_cpu(p->pdSize);
     84			return 0;
     85		}
     86	}
     87
     88	return -ENOENT;
     89}
     90
     91static int hfs_parse_new_pmap(struct super_block *sb, void *buf,
     92		struct new_pmap *pm, sector_t *part_start, sector_t *part_size)
     93{
     94	struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
     95	int size = be32_to_cpu(pm->pmMapBlkCnt);
     96	int buf_size = hfsplus_min_io_size(sb);
     97	int res;
     98	int i = 0;
     99
    100	do {
    101		if (!memcmp(pm->pmPartType, "Apple_HFS", 9) &&
    102		    (sbi->part < 0 || sbi->part == i)) {
    103			*part_start += be32_to_cpu(pm->pmPyPartStart);
    104			*part_size = be32_to_cpu(pm->pmPartBlkCnt);
    105			return 0;
    106		}
    107
    108		if (++i >= size)
    109			return -ENOENT;
    110
    111		pm = (struct new_pmap *)((u8 *)pm + HFSPLUS_SECTOR_SIZE);
    112		if ((u8 *)pm - (u8 *)buf >= buf_size) {
    113			res = hfsplus_submit_bio(sb,
    114						 *part_start + HFS_PMAP_BLK + i,
    115						 buf, (void **)&pm, REQ_OP_READ,
    116						 0);
    117			if (res)
    118				return res;
    119		}
    120	} while (pm->pmSig == cpu_to_be16(HFS_NEW_PMAP_MAGIC));
    121
    122	return -ENOENT;
    123}
    124
    125/*
    126 * Parse the partition map looking for the start and length of a
    127 * HFS/HFS+ partition.
    128 */
    129int hfs_part_find(struct super_block *sb,
    130		sector_t *part_start, sector_t *part_size)
    131{
    132	void *buf, *data;
    133	int res;
    134
    135	buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL);
    136	if (!buf)
    137		return -ENOMEM;
    138
    139	res = hfsplus_submit_bio(sb, *part_start + HFS_PMAP_BLK,
    140				 buf, &data, REQ_OP_READ, 0);
    141	if (res)
    142		goto out;
    143
    144	switch (be16_to_cpu(*((__be16 *)data))) {
    145	case HFS_OLD_PMAP_MAGIC:
    146		res = hfs_parse_old_pmap(sb, data, part_start, part_size);
    147		break;
    148	case HFS_NEW_PMAP_MAGIC:
    149		res = hfs_parse_new_pmap(sb, buf, data, part_start, part_size);
    150		break;
    151	default:
    152		res = -ENOENT;
    153		break;
    154	}
    155out:
    156	kfree(buf);
    157	return res;
    158}