/src/util-linux/libblkid/src/superblocks/bitlocker.c

Source
/*
 * Copyright (C) 2018 Karel Zak <kzak@redhat.com>
 *
 * This file may be redistributed under the terms of the
 * GNU Lesser General Public License.
 */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <ctype.h>
#include <stdint.h>

#include "superblocks.h"

#define BDE_HDR_SIZE  512
#define BDE_HDR_OFFSET  0

struct bde_header_win7 {
/*   0 */ unsigned char boot_entry_point[3];
/*   3 */ unsigned char fs_signature[8];
/*  11 */ unsigned char __dummy1[67 - 11];
/*  67 */ uint32_t      volume_serial;    /* NTFS uses 64bit serial number */
/*  71 */ unsigned char volume_label[11]; /* "NO NAME\x20\x20\x20\x20" only */
/*  82 */ unsigned char __dummy2[160 - 82];
/* 160 */ unsigned char guid[16];   /* BitLocker specific GUID */
/* 176 */ uint64_t      fve_metadata_offset;
} __attribute__((packed));


struct bde_header_togo {
/*   0 */ unsigned char boot_entry_point[3];
/*   3 */ unsigned char fs_signature[8];
/*  11 */ unsigned char __dummy[424 - 11];
/* 424 */ unsigned char guid[16];
/* 440 */ uint64_t      fve_metadata_offset;
} __attribute__((packed));


struct bde_fve_metadata_block_header {
/*   0 */ unsigned char  signature[8];
/*   8 */ unsigned char  __dummy1[10 - 8];
/*  10 */ uint16_t       version;
/*  12 */ unsigned char  __dummy2[64 - 12];
} __attribute__((packed));

struct bde_fve_metadata_header {
/*   0 */ uint32_t      size;
/*   4 */ uint32_t      version;
/*   8 */ uint32_t      header_size;
/*  12 */ uint32_t      size_copy;
/*  16 */ unsigned char volume_identifier[16];
/*  32 */ unsigned char __dummy[48 - 32];
} __attribute__((packed));

struct bde_fve_metadata_entry {
/*   0 */ uint16_t      size;
/*   2 */ uint16_t      entry_type;
/*   4 */ uint16_t      value_type;
/*   6 */ uint16_t      version;
/*   8 */ unsigned char data[];
} __attribute__((packed));

struct bde_fve_metadata {
  struct bde_fve_metadata_block_header block_header;
  struct bde_fve_metadata_header header;
} __attribute__((packed));

enum {
  BDE_VERSION_VISTA = 0,
  BDE_VERSION_WIN7,
  BDE_VERSION_TOGO
};

#define BDE_MAGIC_VISTA   "\xeb\x52\x90-FVE-FS-"
#define BDE_MAGIC_WIN7    "\xeb\x58\x90-FVE-FS-"
#define BDE_MAGIC_TOGO    "\xeb\x58\x90MSWIN4.1"

#define BDE_MAGIC_FVE   "-FVE-FS-"

#define BDE_METADATA_ENTRY_TYPE_DESCRIPTION 0x0007
#define BDE_METADATA_VALUE_TYPE_STRING      0x0002

static int get_bitlocker_type(const unsigned char *buf)
{
  size_t i;
  static const char *const map[] = {
    [BDE_VERSION_VISTA] = BDE_MAGIC_VISTA,
    [BDE_VERSION_WIN7]  = BDE_MAGIC_WIN7,
    [BDE_VERSION_TOGO]  = BDE_MAGIC_TOGO
  };

  for (i = 0; i < ARRAY_SIZE(map); i++) {
    if (memcmp(buf, map[i], 11) == 0)
      return (int) i;
  }

  return -1;
}

/* Returns: < 0 error, 1 nothing, 0 success
 */
static int get_bitlocker_headers(blkid_probe pr,
        int *type,
        const unsigned char **buf_hdr,
        const unsigned char **buf_fve)
{

  const unsigned char *buf;
  const struct bde_fve_metadata *fve;
  uint64_t off = 0;
  int kind;

  if (buf_hdr)
    *buf_hdr = NULL;
  if (buf_fve)
    *buf_fve = NULL;
  if (type)
    *type = -1;

  buf = blkid_probe_get_buffer(pr, BDE_HDR_OFFSET, BDE_HDR_SIZE);
  if (!buf)
    return errno ? -errno : 1;

  kind = get_bitlocker_type(buf);

  /* Check BitLocker header */
  switch (kind) {
  case BDE_VERSION_WIN7:
    off = le64_to_cpu(((const struct bde_header_win7 *) buf)->fve_metadata_offset);
    break;
  case BDE_VERSION_TOGO:
    off = le64_to_cpu(((const struct bde_header_togo *) buf)->fve_metadata_offset);
    break;
  case BDE_VERSION_VISTA:
    goto done;
  default:
    goto nothing;
  }

  if (!off || off % 64)
    goto nothing;
  if (buf_hdr)
    *buf_hdr = buf;

  /* Check Bitlocker FVE metadata header */
  buf = blkid_probe_get_buffer(pr, off, sizeof(struct bde_fve_metadata));
  if (!buf)
    return errno ? -errno : 1;

  fve = (const struct bde_fve_metadata *) buf;
  if (memcmp(fve->block_header.signature, BDE_MAGIC_FVE, sizeof(fve->block_header.signature)) != 0)
    goto nothing;

  if (buf_fve) {
    buf = blkid_probe_get_buffer(pr, off,
      (uint64_t) sizeof(struct bde_fve_metadata_block_header) + le32_to_cpu(fve->header.size));
    if (!buf)
      return errno ? -errno : 1;

    *buf_fve = buf;
  }
done:
  if (type)
    *type = kind;
  return 0;
nothing:
  return 1;
}

/*
 * This is used by vFAT and NTFS prober to avoid collisions with bitlocker.
 */
int blkid_probe_is_bitlocker(blkid_probe pr)
{
  return get_bitlocker_headers(pr, NULL, NULL, NULL) == 0;
}

static int probe_bitlocker(blkid_probe pr,
    const struct blkid_idmag *mag __attribute__((__unused__)))
{
  const unsigned char *buf_fve = NULL;
  const unsigned char *buf_hdr = NULL;
  const struct bde_fve_metadata_entry *entry;
  int rc, kind;
  uint64_t off;

  rc = get_bitlocker_headers(pr, &kind, &buf_hdr, &buf_fve);
  if (rc)
    return rc;

  if (buf_fve) {
    const struct bde_fve_metadata *fve = (const struct bde_fve_metadata *) buf_fve;

    blkid_probe_sprintf_version(pr, "%d", le16_to_cpu(fve->block_header.version));

    for (off = sizeof(struct bde_fve_metadata_header);
         off + sizeof(struct bde_fve_metadata_entry) < le32_to_cpu(fve->header.size);
         off += le16_to_cpu(entry->size)) {
      entry = (const struct bde_fve_metadata_entry *) ((const char *) &fve->header + off);
      if (off % 2 ||
          le16_to_cpu(entry->size) < sizeof(struct bde_fve_metadata_entry) ||
          off + le16_to_cpu(entry->size) > le32_to_cpu(fve->header.size))
        return -1;

      if (le16_to_cpu(entry->entry_type) == BDE_METADATA_ENTRY_TYPE_DESCRIPTION &&
          le16_to_cpu(entry->value_type) == BDE_METADATA_VALUE_TYPE_STRING) {
        blkid_probe_set_utf8label(pr,
          entry->data, le16_to_cpu(entry->size) - sizeof(struct bde_fve_metadata_entry),
          UL_ENCODE_UTF16LE);
        break;
      }
    }

    /* Microsoft GUID format, interpreted as explained by Raymond Chen:
     * https://devblogs.microsoft.com/oldnewthing/20220928-00/?p=107221
     */
    blkid_probe_sprintf_uuid(pr, fve->header.volume_identifier, 16,
      "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
      fve->header.volume_identifier[3], fve->header.volume_identifier[2], /* uint32_t Data1 */
      fve->header.volume_identifier[1], fve->header.volume_identifier[0],
      fve->header.volume_identifier[5], fve->header.volume_identifier[4], /* uint16_t Data2 */
      fve->header.volume_identifier[7], fve->header.volume_identifier[6], /* uint16_t Data3 */
      fve->header.volume_identifier[8], fve->header.volume_identifier[9], /* uint8_t Data4[8] */
      fve->header.volume_identifier[10], fve->header.volume_identifier[11],
      fve->header.volume_identifier[12], fve->header.volume_identifier[13],
      fve->header.volume_identifier[14], fve->header.volume_identifier[15]);
  }
  return 0;
}

/* See header details:
 * https://github.com/libyal/libbde/blob/master/documentation/BitLocker%20Drive%20Encryption%20(BDE)%20format.asciidoc
 */
const struct blkid_idinfo bitlocker_idinfo =
{
  .name   = "BitLocker",
  .usage    = BLKID_USAGE_CRYPTO,
  .probefunc  = probe_bitlocker,
  .magics   =
  {
    { .magic = BDE_MAGIC_VISTA, .len = 11 },
    { .magic = BDE_MAGIC_WIN7,  .len = 11 },
    { .magic = BDE_MAGIC_TOGO,  .len = 11 },
    { NULL }
  }
};

Coverage Report

Created: 2026-07-24 06:26

Line	Count	Source
1		/*
2		* Copyright (C) 2018 Karel Zak <kzak@redhat.com>
3		*
4		* This file may be redistributed under the terms of the
5		* GNU Lesser General Public License.
6		*/
7		#include <stdio.h>
8		#include <stdlib.h>
9		#include <unistd.h>
10		#include <string.h>
11		#include <errno.h>
12		#include <ctype.h>
13		#include <stdint.h>
14
15		#include "superblocks.h"
16
17	1.05k	#define BDE_HDR_SIZE 512
18	1.05k	#define BDE_HDR_OFFSET 0
19
20		struct bde_header_win7 {
21		/* 0 */ unsigned char boot_entry_point[3];
22		/* 3 */ unsigned char fs_signature[8];
23		/* 11 */ unsigned char __dummy1[67 - 11];
24		/* 67 / uint32_t volume_serial; / NTFS uses 64bit serial number */
25		/* 71 / unsigned char volume_label[11]; / "NO NAME\x20\x20\x20\x20" only */
26		/* 82 */ unsigned char __dummy2[160 - 82];
27		/* 160 / unsigned char guid[16]; / BitLocker specific GUID */
28		/* 176 */ uint64_t fve_metadata_offset;
29		} __attribute__((packed));
30
31
32		struct bde_header_togo {
33		/* 0 */ unsigned char boot_entry_point[3];
34		/* 3 */ unsigned char fs_signature[8];
35		/* 11 */ unsigned char __dummy[424 - 11];
36		/* 424 */ unsigned char guid[16];
37		/* 440 */ uint64_t fve_metadata_offset;
38		} __attribute__((packed));
39
40
41		struct bde_fve_metadata_block_header {
42		/* 0 */ unsigned char signature[8];
43		/* 8 */ unsigned char __dummy1[10 - 8];
44		/* 10 */ uint16_t version;
45		/* 12 */ unsigned char __dummy2[64 - 12];
46		} __attribute__((packed));
47
48		struct bde_fve_metadata_header {
49		/* 0 */ uint32_t size;
50		/* 4 */ uint32_t version;
51		/* 8 */ uint32_t header_size;
52		/* 12 */ uint32_t size_copy;
53		/* 16 */ unsigned char volume_identifier[16];
54		/* 32 */ unsigned char __dummy[48 - 32];
55		} __attribute__((packed));
56
57		struct bde_fve_metadata_entry {
58		/* 0 */ uint16_t size;
59		/* 2 */ uint16_t entry_type;
60		/* 4 */ uint16_t value_type;
61		/* 6 */ uint16_t version;
62		/* 8 */ unsigned char data[];
63		} __attribute__((packed));
64
65		struct bde_fve_metadata {
66		struct bde_fve_metadata_block_header block_header;
67		struct bde_fve_metadata_header header;
68		} __attribute__((packed));
69
70		enum {
71		BDE_VERSION_VISTA = 0,
72		BDE_VERSION_WIN7,
73		BDE_VERSION_TOGO
74		};
75
76	1.05k	#define BDE_MAGIC_VISTA "\xeb\x52\x90-FVE-FS-"
77	1.05k	#define BDE_MAGIC_WIN7 "\xeb\x58\x90-FVE-FS-"
78	1.05k	#define BDE_MAGIC_TOGO "\xeb\x58\x90MSWIN4.1"
79
80	155	#define BDE_MAGIC_FVE "-FVE-FS-"
81
82	1.46k	#define BDE_METADATA_ENTRY_TYPE_DESCRIPTION 0x0007
83	6	#define BDE_METADATA_VALUE_TYPE_STRING 0x0002
84
85		static int get_bitlocker_type(const unsigned char *buf)
86	1.05k	{
87	1.05k	size_t i;
88	1.05k	static const char *const map[] = {
89	1.05k	[BDE_VERSION_VISTA] = BDE_MAGIC_VISTA,
90	1.05k	[BDE_VERSION_WIN7] = BDE_MAGIC_WIN7,
91	1.05k	[BDE_VERSION_TOGO] = BDE_MAGIC_TOGO
92	1.05k	};
93
94	3.48k	for (i = 0; i < ARRAY_SIZE(map); i++) {
95	2.96k	if (memcmp(buf, map[i], 11) == 0)
96	542	return (int) i;
97	2.96k	}
98
99	515	return -1;
100	1.05k	}
101
102		/* Returns: < 0 error, 1 nothing, 0 success
103		*/
104		static int get_bitlocker_headers(blkid_probe pr,
105		int *type,
106		const unsigned char **buf_hdr,
107		const unsigned char **buf_fve)
108	1.05k	{
109
110	1.05k	const unsigned char *buf;
111	1.05k	const struct bde_fve_metadata *fve;
112	1.05k	uint64_t off = 0;
113	1.05k	int kind;
114
115	1.05k	if (buf_hdr)
116	303	*buf_hdr = NULL;
117	1.05k	if (buf_fve)
118	303	*buf_fve = NULL;
119	1.05k	if (type)
120	303	*type = -1;
121
122	1.05k	buf = blkid_probe_get_buffer(pr, BDE_HDR_OFFSET, BDE_HDR_SIZE);
123	1.05k	if (!buf)
124	0	return errno ? -errno : 1;
125
126	1.05k	kind = get_bitlocker_type(buf);
127
128		/* Check BitLocker header */
129	1.05k	switch (kind) {
130	193	case BDE_VERSION_WIN7:
131	193	off = le64_to_cpu(((const struct bde_header_win7 *) buf)->fve_metadata_offset);
132	193	break;
133	344	case BDE_VERSION_TOGO:
134	344	off = le64_to_cpu(((const struct bde_header_togo *) buf)->fve_metadata_offset);
135	344	break;
136	5	case BDE_VERSION_VISTA:
137	5	goto done;
138	515	default:
139	515	goto nothing;
140	1.05k	}
141
142	537	if (!off \|\| off % 64)
143	141	goto nothing;
144	396	if (buf_hdr)
145	215	*buf_hdr = buf;
146
147		/* Check Bitlocker FVE metadata header */
148	396	buf = blkid_probe_get_buffer(pr, off, sizeof(struct bde_fve_metadata));
149	396	if (!buf)
150	241	return errno ? -errno : 1;
151
152	155	fve = (const struct bde_fve_metadata *) buf;
153	155	if (memcmp(fve->block_header.signature, BDE_MAGIC_FVE, sizeof(fve->block_header.signature)) != 0)
154	99	goto nothing;
155
156	56	if (buf_fve) {
157	46	buf = blkid_probe_get_buffer(pr, off,
158	46	(uint64_t) sizeof(struct bde_fve_metadata_block_header) + le32_to_cpu(fve->header.size));
159	46	if (!buf)
160	10	return errno ? -errno : 1;
161
162	36	*buf_fve = buf;
163	36	}
164	51	done:
165	51	if (type)
166	39	*type = kind;
167	51	return 0;
168	755	nothing:
169	755	return 1;
170	56	}
171
172		/*
173		* This is used by vFAT and NTFS prober to avoid collisions with bitlocker.
174		*/
175		int blkid_probe_is_bitlocker(blkid_probe pr)
176	754	{
177	754	return get_bitlocker_headers(pr, NULL, NULL, NULL) == 0;
178	754	}
179
180		static int probe_bitlocker(blkid_probe pr,
181		const struct blkid_idmag *mag __attribute__((__unused__)))
182	303	{
183	303	const unsigned char *buf_fve = NULL;
184	303	const unsigned char *buf_hdr = NULL;
185	303	const struct bde_fve_metadata_entry *entry;
186	303	int rc, kind;
187	303	uint64_t off;
188
189	303	rc = get_bitlocker_headers(pr, &kind, &buf_hdr, &buf_fve);
190	303	if (rc)
191	264	return rc;
192
193	39	if (buf_fve) {
194	36	const struct bde_fve_metadata fve = (const struct bde_fve_metadata ) buf_fve;
195
196	36	blkid_probe_sprintf_version(pr, "%d", le16_to_cpu(fve->block_header.version));
197
198	36	for (off = sizeof(struct bde_fve_metadata_header);
199	763	off + sizeof(struct bde_fve_metadata_entry) < le32_to_cpu(fve->header.size);
200	759	off += le16_to_cpu(entry->size)) {
201	759	entry = (const struct bde_fve_metadata_entry ) ((const char ) &fve->header + off);
202	759	if (off % 2 \|\|
203	755	le16_to_cpu(entry->size) < sizeof(struct bde_fve_metadata_entry) \|\|
204	746	off + le16_to_cpu(entry->size) > le32_to_cpu(fve->header.size))
205	29	return -1;
206
207	730	if (le16_to_cpu(entry->entry_type) == BDE_METADATA_ENTRY_TYPE_DESCRIPTION &&
208	6	le16_to_cpu(entry->value_type) == BDE_METADATA_VALUE_TYPE_STRING) {
209	3	blkid_probe_set_utf8label(pr,
210	3	entry->data, le16_to_cpu(entry->size) - sizeof(struct bde_fve_metadata_entry),
211	3	UL_ENCODE_UTF16LE);
212	3	break;
213	3	}
214	730	}
215
216		/* Microsoft GUID format, interpreted as explained by Raymond Chen:
217		* https://devblogs.microsoft.com/oldnewthing/20220928-00/?p=107221
218		*/
219	7	blkid_probe_sprintf_uuid(pr, fve->header.volume_identifier, 16,
220	7	"%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
221	7	fve->header.volume_identifier[3], fve->header.volume_identifier[2], /* uint32_t Data1 */
222	7	fve->header.volume_identifier[1], fve->header.volume_identifier[0],
223	7	fve->header.volume_identifier[5], fve->header.volume_identifier[4], /* uint16_t Data2 */
224	7	fve->header.volume_identifier[7], fve->header.volume_identifier[6], /* uint16_t Data3 */
225	7	fve->header.volume_identifier[8], fve->header.volume_identifier[9], /* uint8_t Data4[8] */
226	7	fve->header.volume_identifier[10], fve->header.volume_identifier[11],
227	7	fve->header.volume_identifier[12], fve->header.volume_identifier[13],
228	7	fve->header.volume_identifier[14], fve->header.volume_identifier[15]);
229	7	}
230	10	return 0;
231	39	}
232
233		/* See header details:
234		* https://github.com/libyal/libbde/blob/master/documentation/BitLocker%20Drive%20Encryption%20(BDE)%20format.asciidoc
235		*/
236		const struct blkid_idinfo bitlocker_idinfo =
237		{
238		.name = "BitLocker",
239		.usage = BLKID_USAGE_CRYPTO,
240		.probefunc = probe_bitlocker,
241		.magics =
242		{
243		{ .magic = BDE_MAGIC_VISTA, .len = 11 },
244		{ .magic = BDE_MAGIC_WIN7, .len = 11 },
245		{ .magic = BDE_MAGIC_TOGO, .len = 11 },
246		{ NULL }
247		}
248		};