ldm.c

linux 内核源代码

/**
 * ldm - Support for Windows Logical Disk Manager (Dynamic Disks)
 *
 * Copyright (C) 2001,2002 Richard Russon <[e-mail]>
 * Copyright (c) 2001-2007 Anton Altaparmakov
 * Copyright (C) 2001,2002 Jakob Kemi <[e-mail]>
 *
 * Documentation is available at http://www.linux-ntfs.org/content/view/19/37/
 *
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation; either version 2 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program (in the main directory of the source in the file COPYING); if
 * not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA  02111-1307  USA
 */

#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/stringify.h>
#include "ldm.h"
#include "check.h"
#include "msdos.h"

/**
 * ldm_debug/info/error/crit - Output an error message
 * @f:    A printf format string containing the message
 * @...:  Variables to substitute into @f
 *
 * ldm_debug() writes a DEBUG level message to the syslog but only if the
 * driver was compiled with debug enabled. Otherwise, the call turns into a NOP.
 */
#ifndef CONFIG_LDM_DEBUG
#define ldm_debug(...)	do {} while (0)
#else
#define ldm_debug(f, a...) _ldm_printk (KERN_DEBUG, __FUNCTION__, f, ##a)
#endif

#define ldm_crit(f, a...)  _ldm_printk (KERN_CRIT,  __FUNCTION__, f, ##a)
#define ldm_error(f, a...) _ldm_printk (KERN_ERR,   __FUNCTION__, f, ##a)
#define ldm_info(f, a...)  _ldm_printk (KERN_INFO,  __FUNCTION__, f, ##a)

__attribute__ ((format (printf, 3, 4)))
static void _ldm_printk (const char *level, const char *function,
			 const char *fmt, ...)
{
	static char buf[128];
	va_list args;

	va_start (args, fmt);
	vsnprintf (buf, sizeof (buf), fmt, args);
	va_end (args);

	printk ("%s%s(): %s\n", level, function, buf);
}

/**
 * ldm_parse_hexbyte - Convert a ASCII hex number to a byte
 * @src:  Pointer to at least 2 characters to convert.
 *
 * Convert a two character ASCII hex string to a number.
 *
 * Return:  0-255  Success, the byte was parsed correctly
 *          -1     Error, an invalid character was supplied
 */
static int ldm_parse_hexbyte (const u8 *src)
{
	unsigned int x;		/* For correct wrapping */
	int h;

	/* high part */
	if      ((x = src[0] - '0') <= '9'-'0') h = x;
	else if ((x = src[0] - 'a') <= 'f'-'a') h = x+10;
	else if ((x = src[0] - 'A') <= 'F'-'A') h = x+10;
	else return -1;
	h <<= 4;

	/* low part */
	if ((x = src[1] - '0') <= '9'-'0') return h | x;
	if ((x = src[1] - 'a') <= 'f'-'a') return h | (x+10);
	if ((x = src[1] - 'A') <= 'F'-'A') return h | (x+10);
	return -1;
}

/**
 * ldm_parse_guid - Convert GUID from ASCII to binary
 * @src:   36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
 * @dest:  Memory block to hold binary GUID (16 bytes)
 *
 * N.B. The GUID need not be NULL terminated.
 *
 * Return:  'true'   @dest contains binary GUID
 *          'false'  @dest contents are undefined
 */
static bool ldm_parse_guid (const u8 *src, u8 *dest)
{
	static const int size[] = { 4, 2, 2, 2, 6 };
	int i, j, v;

	if (src[8]  != '-' || src[13] != '-' ||
	    src[18] != '-' || src[23] != '-')
		return false;

	for (j = 0; j < 5; j++, src++)
		for (i = 0; i < size[j]; i++, src+=2, *dest++ = v)
			if ((v = ldm_parse_hexbyte (src)) < 0)
				return false;

	return true;
}

/**
 * ldm_parse_privhead - Read the LDM Database PRIVHEAD structure
 * @data:  Raw database PRIVHEAD structure loaded from the device
 * @ph:    In-memory privhead structure in which to return parsed information
 *
 * This parses the LDM database PRIVHEAD structure supplied in @data and
 * sets up the in-memory privhead structure @ph with the obtained information.
 *
 * Return:  'true'   @ph contains the PRIVHEAD data
 *          'false'  @ph contents are undefined
 */
static bool ldm_parse_privhead(const u8 *data, struct privhead *ph)
{
	bool is_vista = false;

	BUG_ON(!data || !ph);
	if (MAGIC_PRIVHEAD != BE64(data)) {
		ldm_error("Cannot find PRIVHEAD structure. LDM database is"
			" corrupt. Aborting.");
		return false;
	}
	ph->ver_major = BE16(data + 0x000C);
	ph->ver_minor = BE16(data + 0x000E);
	ph->logical_disk_start = BE64(data + 0x011B);
	ph->logical_disk_size = BE64(data + 0x0123);
	ph->config_start = BE64(data + 0x012B);
	ph->config_size = BE64(data + 0x0133);
	/* Version 2.11 is Win2k/XP and version 2.12 is Vista. */
	if (ph->ver_major == 2 && ph->ver_minor == 12)
		is_vista = true;
	if (!is_vista && (ph->ver_major != 2 || ph->ver_minor != 11)) {
		ldm_error("Expected PRIVHEAD version 2.11 or 2.12, got %d.%d."
			" Aborting.", ph->ver_major, ph->ver_minor);
		return false;
	}
	ldm_debug("PRIVHEAD version %d.%d (Windows %s).", ph->ver_major,
			ph->ver_minor, is_vista ? "Vista" : "2000/XP");
	if (ph->config_size != LDM_DB_SIZE) {	/* 1 MiB in sectors. */
		/* Warn the user and continue, carefully. */
		ldm_info("Database is normally %u bytes, it claims to "
			"be %llu bytes.", LDM_DB_SIZE,
			(unsigned long long)ph->config_size);
	}
	if ((ph->logical_disk_size == 0) || (ph->logical_disk_start +
			ph->logical_disk_size > ph->config_start)) {
		ldm_error("PRIVHEAD disk size doesn't match real disk size");
		return false;
	}
	if (!ldm_parse_guid(data + 0x0030, ph->disk_id)) {
		ldm_error("PRIVHEAD contains an invalid GUID.");
		return false;
	}
	ldm_debug("Parsed PRIVHEAD successfully.");
	return true;
}

/**
 * ldm_parse_tocblock - Read the LDM Database TOCBLOCK structure
 * @data:  Raw database TOCBLOCK structure loaded from the device
 * @toc:   In-memory toc structure in which to return parsed information
 *
 * This parses the LDM Database TOCBLOCK (table of contents) structure supplied
 * in @data and sets up the in-memory tocblock structure @toc with the obtained
 * information.
 *
 * N.B.  The *_start and *_size values returned in @toc are not range-checked.
 *
 * Return:  'true'   @toc contains the TOCBLOCK data
 *          'false'  @toc contents are undefined
 */
static bool ldm_parse_tocblock (const u8 *data, struct tocblock *toc)
{
	BUG_ON (!data || !toc);

	if (MAGIC_TOCBLOCK != BE64 (data)) {
		ldm_crit ("Cannot find TOCBLOCK, database may be corrupt.");
		return false;
	}
	strncpy (toc->bitmap1_name, data + 0x24, sizeof (toc->bitmap1_name));
	toc->bitmap1_name[sizeof (toc->bitmap1_name) - 1] = 0;
	toc->bitmap1_start = BE64 (data + 0x2E);
	toc->bitmap1_size  = BE64 (data + 0x36);

	if (strncmp (toc->bitmap1_name, TOC_BITMAP1,
			sizeof (toc->bitmap1_name)) != 0) {
		ldm_crit ("TOCBLOCK's first bitmap is '%s', should be '%s'.",
				TOC_BITMAP1, toc->bitmap1_name);
		return false;
	}
	strncpy (toc->bitmap2_name, data + 0x46, sizeof (toc->bitmap2_name));
	toc->bitmap2_name[sizeof (toc->bitmap2_name) - 1] = 0;
	toc->bitmap2_start = BE64 (data + 0x50);
	toc->bitmap2_size  = BE64 (data + 0x58);
	if (strncmp (toc->bitmap2_name, TOC_BITMAP2,
			sizeof (toc->bitmap2_name)) != 0) {
		ldm_crit ("TOCBLOCK's second bitmap is '%s', should be '%s'.",
				TOC_BITMAP2, toc->bitmap2_name);
		return false;
	}
	ldm_debug ("Parsed TOCBLOCK successfully.");
	return true;
}

/**
 * ldm_parse_vmdb - Read the LDM Database VMDB structure
 * @data:  Raw database VMDB structure loaded from the device
 * @vm:    In-memory vmdb structure in which to return parsed information
 *
 * This parses the LDM Database VMDB structure supplied in @data and sets up
 * the in-memory vmdb structure @vm with the obtained information.
 *
 * N.B.  The *_start, *_size and *_seq values will be range-checked later.
 *
 * Return:  'true'   @vm contains VMDB info
 *          'false'  @vm contents are undefined
 */
static bool ldm_parse_vmdb (const u8 *data, struct vmdb *vm)
{
	BUG_ON (!data || !vm);

	if (MAGIC_VMDB != BE32 (data)) {
		ldm_crit ("Cannot find the VMDB, database may be corrupt.");
		return false;
	}

	vm->ver_major = BE16 (data + 0x12);
	vm->ver_minor = BE16 (data + 0x14);
	if ((vm->ver_major != 4) || (vm->ver_minor != 10)) {
		ldm_error ("Expected VMDB version %d.%d, got %d.%d. "
			"Aborting.", 4, 10, vm->ver_major, vm->ver_minor);
		return false;
	}

	vm->vblk_size     = BE32 (data + 0x08);
	vm->vblk_offset   = BE32 (data + 0x0C);
	vm->last_vblk_seq = BE32 (data + 0x04);

	ldm_debug ("Parsed VMDB successfully.");
	return true;
}

/**
 * ldm_compare_privheads - Compare two privhead objects
 * @ph1:  First privhead
 * @ph2:  Second privhead
 *
 * This compares the two privhead structures @ph1 and @ph2.
 *
 * Return:  'true'   Identical
 *          'false'  Different
 */
static bool ldm_compare_privheads (const struct privhead *ph1,
				   const struct privhead *ph2)
{
	BUG_ON (!ph1 || !ph2);

	return ((ph1->ver_major          == ph2->ver_major)		&&
		(ph1->ver_minor          == ph2->ver_minor)		&&
		(ph1->logical_disk_start == ph2->logical_disk_start)	&&
		(ph1->logical_disk_size  == ph2->logical_disk_size)	&&
		(ph1->config_start       == ph2->config_start)		&&
		(ph1->config_size        == ph2->config_size)		&&
		!memcmp (ph1->disk_id, ph2->disk_id, GUID_SIZE));
}

/**
 * ldm_compare_tocblocks - Compare two tocblock objects
 * @toc1:  First toc
 * @toc2:  Second toc
 *
 * This compares the two tocblock structures @toc1 and @toc2.
 *
 * Return:  'true'   Identical
 *          'false'  Different
 */
static bool ldm_compare_tocblocks (const struct tocblock *toc1,
				   const struct tocblock *toc2)
{
	BUG_ON (!toc1 || !toc2);

	return ((toc1->bitmap1_start == toc2->bitmap1_start)	&&
		(toc1->bitmap1_size  == toc2->bitmap1_size)	&&
		(toc1->bitmap2_start == toc2->bitmap2_start)	&&
		(toc1->bitmap2_size  == toc2->bitmap2_size)	&&
		!strncmp (toc1->bitmap1_name, toc2->bitmap1_name,
			sizeof (toc1->bitmap1_name))		&&
		!strncmp (toc1->bitmap2_name, toc2->bitmap2_name,
			sizeof (toc1->bitmap2_name)));
}

/**
 * ldm_validate_privheads - Compare the primary privhead with its backups
 * @bdev:  Device holding the LDM Database
 * @ph1:   Memory struct to fill with ph contents
 *
 * Read and compare all three privheads from disk.
 *
 * The privheads on disk show the size and location of the main disk area and
 * the configuration area (the database).  The values are range-checked against
 * @hd, which contains the real size of the disk.
 *
 * Return:  'true'   Success
 *          'false'  Error
 */
static bool ldm_validate_privheads (struct block_device *bdev,
				    struct privhead *ph1)
{
	static const int off[3] = { OFF_PRIV1, OFF_PRIV2, OFF_PRIV3 };
	struct privhead *ph[3] = { ph1 };
	Sector sect;
	u8 *data;
	bool result = false;
	long num_sects;
	int i;

	BUG_ON (!bdev || !ph1);

	ph[1] = kmalloc (sizeof (*ph[1]), GFP_KERNEL);
	ph[2] = kmalloc (sizeof (*ph[2]), GFP_KERNEL);
	if (!ph[1] || !ph[2]) {
		ldm_crit ("Out of memory.");
		goto out;
	}

	/* off[1 & 2] are relative to ph[0]->config_start */
	ph[0]->config_start = 0;

	/* Read and parse privheads */
	for (i = 0; i < 3; i++) {
		data = read_dev_sector (bdev,
			ph[0]->config_start + off[i], &sect);
		if (!data) {
			ldm_crit ("Disk read failed.");
			goto out;
		}
		result = ldm_parse_privhead (data, ph[i]);
		put_dev_sector (sect);
		if (!result) {
			ldm_error ("Cannot find PRIVHEAD %d.", i+1); /* Log again */
			if (i < 2)
				goto out;	/* Already logged */
			else
				break;	/* FIXME ignore for now, 3rd PH can fail on odd-sized disks */
		}
	}

	num_sects = bdev->bd_inode->i_size >> 9;

	if ((ph[0]->config_start > num_sects) ||
	   ((ph[0]->config_start + ph[0]->config_size) > num_sects)) {
		ldm_crit ("Database extends beyond the end of the disk.");
		goto out;
	}

	if ((ph[0]->logical_disk_start > ph[0]->config_start) ||
	   ((ph[0]->logical_disk_start + ph[0]->logical_disk_size)
		    > ph[0]->config_start)) {
		ldm_crit ("Disk and database overlap.");
		goto out;
	}

	if (!ldm_compare_privheads (ph[0], ph[1])) {
		ldm_crit ("Primary and backup PRIVHEADs don't match.");
		goto out;
	}
	/* FIXME ignore this for now
	if (!ldm_compare_privheads (ph[0], ph[2])) {
		ldm_crit ("Primary and backup PRIVHEADs don't match.");
		goto out;
	}*/
	ldm_debug ("Validated PRIVHEADs successfully.");
	result = true;
out:
	kfree (ph[1]);
	kfree (ph[2]);
	return result;
}

/**
 * ldm_validate_tocblocks - Validate the table of contents and its backups
 * @bdev:  Device holding the LDM Database
 * @base:  Offset, into @bdev, of the database
 * @ldb:   Cache of the database structures
 *
 * Find and compare the four tables of contents of the LDM Database stored on
 * @bdev and return the parsed information into @toc1.
 *
 * The offsets and sizes of the configs are range-checked against a privhead.
 *
 * Return:  'true'   @toc1 contains validated TOCBLOCK info
 *          'false'  @toc1 contents are undefined
 */
static bool ldm_validate_tocblocks(struct block_device *bdev,
	unsigned long base, struct ldmdb *ldb)
{
	static const int off[4] = { OFF_TOCB1, OFF_TOCB2, OFF_TOCB3, OFF_TOCB4};
	struct tocblock *tb[4];
	struct privhead *ph;
	Sector sect;
	u8 *data;
	int i, nr_tbs;
	bool result = false;

	BUG_ON(!bdev || !ldb);
	ph = &ldb->ph;
	tb[0] = &ldb->toc;
	tb[1] = kmalloc(sizeof(*tb[1]) * 3, GFP_KERNEL);
	if (!tb[1]) {
		ldm_crit("Out of memory.");
		goto err;
	}
	tb[2] = (struct tocblock*)((u8*)tb[1] + sizeof(*tb[1]));
	tb[3] = (struct tocblock*)((u8*)tb[2] + sizeof(*tb[2]));
	/*
	 * Try to read and parse all four TOCBLOCKs.
	 *
	 * Windows Vista LDM v2.12 does not always have all four TOCBLOCKs so
	 * skip any that fail as long as we get at least one valid TOCBLOCK.
	 */
	for (nr_tbs = i = 0; i < 4; i++) {
		data = read_dev_sector(bdev, base + off[i], &sect);
		if (!data) {
			ldm_error("Disk read failed for TOCBLOCK %d.", i);
			continue;
		}
		if (ldm_parse_tocblock(data, tb[nr_tbs]))
			nr_tbs++;
		put_dev_sector(sect);
	}
	if (!nr_tbs) {
		ldm_crit("Failed to find a valid TOCBLOCK.");
		goto err;
	}
	/* Range check the TOCBLOCK against a privhead. */
	if (((tb[0]->bitmap1_start + tb[0]->bitmap1_size) > ph->config_size) ||
			((tb[0]->bitmap2_start + tb[0]->bitmap2_size) >
			ph->config_size)) {
		ldm_crit("The bitmaps are out of range.  Giving up.");
		goto err;
	}
	/* Compare all loaded TOCBLOCKs. */
	for (i = 1; i < nr_tbs; i++) {
		if (!ldm_compare_tocblocks(tb[0], tb[i])) {
			ldm_crit("TOCBLOCKs 0 and %d do not match.", i);
			goto err;
		}
	}
	ldm_debug("Validated %d TOCBLOCKs successfully.", nr_tbs);
	result = true;
err:
	kfree(tb[1]);
	return result;
}

/**
 * ldm_validate_vmdb - Read the VMDB and validate it
 * @bdev:  Device holding the LDM Database
 * @base:  Offset, into @bdev, of the database
 * @ldb:   Cache of the database structures
 *
 * Find the vmdb of the LDM Database stored on @bdev and return the parsed
 * information in @ldb.
 *
 * Return:  'true'   @ldb contains validated VBDB info
 *          'false'  @ldb contents are undefined
 */
static bool ldm_validate_vmdb (struct block_device *bdev, unsigned long base,
			       struct ldmdb *ldb)
{
	Sector sect;
	u8 *data;
	bool result = false;
	struct vmdb *vm;
	struct tocblock *toc;

	BUG_ON (!bdev || !ldb);

	vm  = &ldb->vm;
	toc = &ldb->toc;

	data = read_dev_sector (bdev, base + OFF_VMDB, &sect);
	if (!data) {
		ldm_crit ("Disk read failed.");
		return false;
	}

	if (!ldm_parse_vmdb (data, vm))
		goto out;				/* Already logged */

	/* Are there uncommitted transactions? */
	if (BE16(data + 0x10) != 0x01) {
		ldm_crit ("Database is not in a consistent state.  Aborting.");
		goto out;
	}

	if (vm->vblk_offset != 512)
		ldm_info ("VBLKs start at offset 0x%04x.", vm->vblk_offset);

	/*