/*
* storage_file_probe.c: file utility functions for FS storage backend
*
* Copyright (C) 2007-2017 Red Hat, Inc.
* Copyright (C) 2007-2008 Daniel P. Berrange
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see
* .
*/
#include
#include
#include
#include
#include "internal.h"
#include "storage_file_probe.h"
#include "storage_source_conf.h"
#include "viralloc.h"
#include "virbitmap.h"
#include "virendian.h"
#include "virfile.h"
#include "virlog.h"
#define VIR_FROM_THIS VIR_FROM_STORAGE
VIR_LOG_INIT("storage_file.storagefileprobe");
enum lv_endian {
LV_LITTLE_ENDIAN = 1, /* 1234 */
LV_BIG_ENDIAN /* 4321 */
};
enum {
BACKING_STORE_OK,
BACKING_STORE_INVALID,
BACKING_STORE_ERROR,
};
#define FILE_TYPE_VERSIONS_LAST 3
struct FileEncryptionInfo {
int format; /* Encryption format to assign */
int magicOffset; /* Byte offset of the magic */
const char *magic; /* Optional string of magic */
enum lv_endian endian; /* Endianness of file format */
int versionOffset; /* Byte offset from start of file
* where we find version number,
* -1 to always fail the version test,
* -2 to always pass the version test */
int versionSize; /* Size in bytes of version data (0, 2, or 4) */
int versionNumbers[FILE_TYPE_VERSIONS_LAST];
/* Version numbers to validate. Zeroes are ignored. */
int modeOffset; /* Byte offset of the format native encryption mode */
char modeValue; /* Value expected at offset */
int payloadOffset; /* start offset of the volume data (in 512 byte sectors) */
};
struct FileTypeInfo {
int magicOffset; /* Byte offset of the magic */
const char *magic; /* Optional string of file magic
* to check at head of file */
enum lv_endian endian; /* Endianness of file format */
int versionOffset; /* Byte offset from start of file
* where we find version number,
* -1 to always fail the version test,
* -2 to always pass the version test */
int versionSize; /* Size in bytes of version data (0, 2, or 4) */
int versionNumbers[FILE_TYPE_VERSIONS_LAST];
/* Version numbers to validate. Zeroes are ignored. */
int sizeOffset; /* Byte offset from start of file
* where we find capacity info,
* -1 to use st_size as capacity */
int sizeBytes; /* Number of bytes for size field */
int sizeMultiplier; /* A scaling factor if size is not in bytes */
/* Store a COW base image path (possibly relative),
* or NULL if there is no COW base image, to RES;
* return BACKING_STORE_* */
const struct FileEncryptionInfo *cryptInfo; /* Encryption info */
int (*getBackingStore)(char **res, int *format,
const char *buf, size_t buf_size);
int (*getFeatures)(virBitmapPtr *features, int format,
char *buf, ssize_t len);
};
static int cowGetBackingStore(char **, int *,
const char *, size_t);
static int qcowXGetBackingStore(char **, int *,
const char *, size_t);
static int qcow2GetFeatures(virBitmapPtr *features, int format,
char *buf, ssize_t len);
static int vmdk4GetBackingStore(char **, int *,
const char *, size_t);
static int
qedGetBackingStore(char **, int *, const char *, size_t);
#define QCOWX_HDR_VERSION (4)
#define QCOWX_HDR_BACKING_FILE_OFFSET (QCOWX_HDR_VERSION+4)
#define QCOWX_HDR_BACKING_FILE_SIZE (QCOWX_HDR_BACKING_FILE_OFFSET+8)
#define QCOWX_HDR_IMAGE_SIZE (QCOWX_HDR_BACKING_FILE_SIZE+4+4)
#define QCOW1_HDR_CRYPT (QCOWX_HDR_IMAGE_SIZE+8+1+1+2)
#define QCOW2_HDR_CRYPT (QCOWX_HDR_IMAGE_SIZE+8)
#define QCOW1_HDR_TOTAL_SIZE (QCOW1_HDR_CRYPT+4+8)
#define QCOW2_HDR_TOTAL_SIZE (QCOW2_HDR_CRYPT+4+4+8+8+4+4+8)
#define QCOW2_HDR_EXTENSION_END 0
#define QCOW2_HDR_EXTENSION_BACKING_FORMAT 0xE2792ACA
#define QCOW2v3_HDR_FEATURES_INCOMPATIBLE (QCOW2_HDR_TOTAL_SIZE)
#define QCOW2v3_HDR_FEATURES_COMPATIBLE (QCOW2v3_HDR_FEATURES_INCOMPATIBLE+8)
#define QCOW2v3_HDR_FEATURES_AUTOCLEAR (QCOW2v3_HDR_FEATURES_COMPATIBLE+8)
/* The location of the header size [4 bytes] */
#define QCOW2v3_HDR_SIZE (QCOW2_HDR_TOTAL_SIZE+8+8+8+4)
#define QED_HDR_FEATURES_OFFSET (4+4+4+4)
#define QED_HDR_IMAGE_SIZE (QED_HDR_FEATURES_OFFSET+8+8+8+8)
#define QED_HDR_BACKING_FILE_OFFSET (QED_HDR_IMAGE_SIZE+8)
#define QED_HDR_BACKING_FILE_SIZE (QED_HDR_BACKING_FILE_OFFSET+4)
#define QED_F_BACKING_FILE 0x01
#define QED_F_BACKING_FORMAT_NO_PROBE 0x04
#define PLOOP_IMAGE_SIZE_OFFSET 36
#define PLOOP_SIZE_MULTIPLIER 512
#define LUKS_HDR_MAGIC_LEN 6
#define LUKS_HDR_VERSION_LEN 2
#define LUKS_HDR_CIPHER_NAME_LEN 32
#define LUKS_HDR_CIPHER_MODE_LEN 32
#define LUKS_HDR_HASH_SPEC_LEN 32
#define LUKS_HDR_PAYLOAD_LEN 4
/* Format described by qemu commit id '3e308f20e' */
#define LUKS_HDR_VERSION_OFFSET LUKS_HDR_MAGIC_LEN
#define LUKS_HDR_PAYLOAD_OFFSET (LUKS_HDR_MAGIC_LEN+\
LUKS_HDR_VERSION_LEN+\
LUKS_HDR_CIPHER_NAME_LEN+\
LUKS_HDR_CIPHER_MODE_LEN+\
LUKS_HDR_HASH_SPEC_LEN)
static struct FileEncryptionInfo const luksEncryptionInfo[] = {
{
.format = VIR_STORAGE_ENCRYPTION_FORMAT_LUKS,
/* Magic is 'L','U','K','S', 0xBA, 0xBE */
.magicOffset = 0,
.magic = "\x4c\x55\x4b\x53\xba\xbe",
.endian = LV_BIG_ENDIAN,
.versionOffset = LUKS_HDR_VERSION_OFFSET,
.versionSize = LUKS_HDR_VERSION_LEN,
.versionNumbers = {1},
.modeOffset = -1,
.modeValue = -1,
.payloadOffset = LUKS_HDR_PAYLOAD_OFFSET,
},
{ 0 }
};
static struct FileEncryptionInfo const qcow1EncryptionInfo[] = {
{
.format = VIR_STORAGE_ENCRYPTION_FORMAT_QCOW,
.magicOffset = 0,
.magic = NULL,
.endian = LV_BIG_ENDIAN,
.versionOffset = -1,
.versionSize = 0,
.versionNumbers = {},
.modeOffset = QCOW1_HDR_CRYPT,
.modeValue = 1,
.payloadOffset = -1,
},
{ 0 }
};
static struct FileEncryptionInfo const qcow2EncryptionInfo[] = {
{
.format = VIR_STORAGE_ENCRYPTION_FORMAT_QCOW,
.magicOffset = 0,
.magic = NULL,
.endian = LV_BIG_ENDIAN,
.versionOffset = -1,
.versionSize = 0,
.versionNumbers = {},
.modeOffset = QCOW2_HDR_CRYPT,
.modeValue = 1,
.payloadOffset = -1,
},
{
.format = VIR_STORAGE_ENCRYPTION_FORMAT_LUKS,
.magicOffset = 0,
.magic = NULL,
.endian = LV_BIG_ENDIAN,
.versionOffset = -1,
.versionSize = 0,
.versionNumbers = {},
.modeOffset = QCOW2_HDR_CRYPT,
.modeValue = 2,
.payloadOffset = -1,
},
{ 0 }
};
static struct FileTypeInfo const fileTypeInfo[] = {
[VIR_STORAGE_FILE_NONE] = { 0, NULL, LV_LITTLE_ENDIAN,
-1, 0, {0}, 0, 0, 0, NULL, NULL, NULL },
[VIR_STORAGE_FILE_RAW] = { 0, NULL, LV_LITTLE_ENDIAN,
-1, 0, {0}, 0, 0, 0,
luksEncryptionInfo,
NULL, NULL },
[VIR_STORAGE_FILE_DIR] = { 0, NULL, LV_LITTLE_ENDIAN,
-1, 0, {0}, 0, 0, 0, NULL, NULL, NULL },
[VIR_STORAGE_FILE_BOCHS] = {
/*"Bochs Virtual HD Image", */ /* Untested */
0, NULL,
LV_LITTLE_ENDIAN, 64, 4, {0x20000},
32+16+16+4+4+4+4+4, 8, 1, NULL, NULL, NULL
},
[VIR_STORAGE_FILE_CLOOP] = {
/* #!/bin/sh
#V2.0 Format
modprobe cloop file=$0 && mount -r -t iso9660 /dev/cloop $1
*/ /* Untested */
0, NULL,
LV_LITTLE_ENDIAN, -1, 0, {0},
-1, 0, 0, NULL, NULL, NULL
},
[VIR_STORAGE_FILE_DMG] = {
/* XXX QEMU says there's no magic for dmg,
* /usr/share/misc/magic lists double magic (both offsets
* would have to match) but then disables that check. */
0, NULL,
0, -1, 0, {0},
-1, 0, 0, NULL, NULL, NULL
},
[VIR_STORAGE_FILE_ISO] = {
32769, "CD001",
LV_LITTLE_ENDIAN, -2, 0, {0},
-1, 0, 0, NULL, NULL, NULL
},
[VIR_STORAGE_FILE_VPC] = {
0, "conectix",
LV_BIG_ENDIAN, 12, 4, {0x10000},
8 + 4 + 4 + 8 + 4 + 4 + 2 + 2 + 4, 8, 1, NULL, NULL, NULL
},
/* TODO: add getBackingStore function */
[VIR_STORAGE_FILE_VDI] = {
64, "\x7f\x10\xda\xbe",
LV_LITTLE_ENDIAN, 68, 4, {0x00010001},
64 + 5 * 4 + 256 + 7 * 4, 8, 1, NULL, NULL, NULL},
/* Not direct file formats, but used for various drivers */
[VIR_STORAGE_FILE_FAT] = { 0, NULL, LV_LITTLE_ENDIAN,
-1, 0, {0}, 0, 0, 0, NULL, NULL, NULL },
[VIR_STORAGE_FILE_VHD] = { 0, NULL, LV_LITTLE_ENDIAN,
-1, 0, {0}, 0, 0, 0, NULL, NULL, NULL },
[VIR_STORAGE_FILE_PLOOP] = { 0, "WithouFreSpacExt", LV_LITTLE_ENDIAN,
-2, 0, {0}, PLOOP_IMAGE_SIZE_OFFSET, 0,
PLOOP_SIZE_MULTIPLIER, NULL, NULL, NULL },
/* All formats with a backing store probe below here */
[VIR_STORAGE_FILE_COW] = {
0, "OOOM",
LV_BIG_ENDIAN, 4, 4, {2},
4+4+1024+4, 8, 1, NULL, cowGetBackingStore, NULL
},
[VIR_STORAGE_FILE_QCOW] = {
0, "QFI",
LV_BIG_ENDIAN, 4, 4, {1},
QCOWX_HDR_IMAGE_SIZE, 8, 1,
qcow1EncryptionInfo,
qcowXGetBackingStore, NULL
},
[VIR_STORAGE_FILE_QCOW2] = {
0, "QFI",
LV_BIG_ENDIAN, 4, 4, {2, 3},
QCOWX_HDR_IMAGE_SIZE, 8, 1,
qcow2EncryptionInfo,
qcowXGetBackingStore,
qcow2GetFeatures
},
[VIR_STORAGE_FILE_QED] = {
/* https://wiki.qemu.org/Features/QED */
0, "QED",
LV_LITTLE_ENDIAN, -2, 0, {0},
QED_HDR_IMAGE_SIZE, 8, 1, NULL, qedGetBackingStore, NULL
},
[VIR_STORAGE_FILE_VMDK] = {
0, "KDMV",
LV_LITTLE_ENDIAN, 4, 4, {1, 2, 3},
4+4+4, 8, 512, NULL, vmdk4GetBackingStore, NULL
},
};
G_STATIC_ASSERT(G_N_ELEMENTS(fileTypeInfo) == VIR_STORAGE_FILE_LAST);
/* qcow2 compatible features in the order they appear on-disk */
enum qcow2CompatibleFeature {
QCOW2_COMPATIBLE_FEATURE_LAZY_REFCOUNTS = 0,
QCOW2_COMPATIBLE_FEATURE_LAST
};
/* conversion to virStorageFileFeature */
static const int qcow2CompatibleFeatureArray[] = {
VIR_STORAGE_FILE_FEATURE_LAZY_REFCOUNTS,
};
G_STATIC_ASSERT(G_N_ELEMENTS(qcow2CompatibleFeatureArray) ==
QCOW2_COMPATIBLE_FEATURE_LAST);
static int
cowGetBackingStore(char **res,
int *format,
const char *buf,
size_t buf_size)
{
#define COW_FILENAME_MAXLEN 1024
*res = NULL;
*format = VIR_STORAGE_FILE_AUTO;
if (buf_size < 4+4+ COW_FILENAME_MAXLEN)
return BACKING_STORE_INVALID;
if (buf[4+4] == '\0') { /* cow_header_v2.backing_file[0] */
*format = VIR_STORAGE_FILE_NONE;
return BACKING_STORE_OK;
}
*res = g_strndup((const char *)buf + 4 + 4, COW_FILENAME_MAXLEN);
return BACKING_STORE_OK;
}
static int
qcow2GetExtensions(const char *buf,
size_t buf_size,
int *backingFormat)
{
size_t offset;
size_t extension_start;
size_t extension_end;
int version = virReadBufInt32BE(buf + QCOWX_HDR_VERSION);
if (version < 2) {
/* QCow1 doesn't have the extensions capability
* used to store backing format */
return 0;
}
if (version == 2)
extension_start = QCOW2_HDR_TOTAL_SIZE;
else
extension_start = virReadBufInt32BE(buf + QCOW2v3_HDR_SIZE);
/*
* Traditionally QCow2 files had a layout of
*
* [header]
* [backingStoreName]
*
* Although the backingStoreName typically followed
* the header immediately, this was not required by
* the format. By specifying a higher byte offset for
* the backing file offset in the header, it was
* possible to leave space between the header and
* start of backingStore.
*
* This hack is now used to store extensions to the
* qcow2 format:
*
* [header]
* [extensions]
* [backingStoreName]
*
* Thus the file region to search for extensions is
* between the end of the header (QCOW2_HDR_TOTAL_SIZE)
* and the start of the backingStoreName (offset)
*
* for qcow2 v3 images, the length of the header
* is stored at QCOW2v3_HDR_SIZE
*/
extension_end = virReadBufInt64BE(buf + QCOWX_HDR_BACKING_FILE_OFFSET);
if (extension_end > buf_size)
return -1;
/*
* The extensions take format of
*
* int32: magic
* int32: length
* byte[length]: payload
*
* Unknown extensions can be ignored by skipping
* over "length" bytes in the data stream.
*/
offset = extension_start;
while (offset < (buf_size-8) &&
offset < (extension_end-8)) {
unsigned int magic = virReadBufInt32BE(buf + offset);
unsigned int len = virReadBufInt32BE(buf + offset + 4);
offset += 8;
if ((offset + len) < offset)
break;
if ((offset + len) > buf_size)
break;
switch (magic) {
case QCOW2_HDR_EXTENSION_BACKING_FORMAT: {
g_autofree char *tmp = NULL;
if (!backingFormat)
break;
tmp = g_new0(char, len + 1);
memcpy(tmp, buf + offset, len);
tmp[len] = '\0';
*backingFormat = virStorageFileFormatTypeFromString(tmp);
if (*backingFormat <= VIR_STORAGE_FILE_NONE)
return -1;
break;
}
case QCOW2_HDR_EXTENSION_END:
return 0;
}
offset += len;
}
return 0;
}
static int
qcowXGetBackingStore(char **res,
int *format,
const char *buf,
size_t buf_size)
{
unsigned long long offset;
unsigned int size;
*res = NULL;
*format = VIR_STORAGE_FILE_AUTO;
if (buf_size < QCOWX_HDR_BACKING_FILE_OFFSET+8+4)
return BACKING_STORE_INVALID;
offset = virReadBufInt64BE(buf + QCOWX_HDR_BACKING_FILE_OFFSET);
if (offset > buf_size)
return BACKING_STORE_INVALID;
if (offset == 0) {
*format = VIR_STORAGE_FILE_NONE;
return BACKING_STORE_OK;
}
size = virReadBufInt32BE(buf + QCOWX_HDR_BACKING_FILE_SIZE);
if (size == 0) {
*format = VIR_STORAGE_FILE_NONE;
return BACKING_STORE_OK;
}
if (size > 1023)
return BACKING_STORE_INVALID;
if (offset + size > buf_size || offset + size < offset)
return BACKING_STORE_INVALID;
*res = g_new0(char, size + 1);
memcpy(*res, buf + offset, size);
(*res)[size] = '\0';
if (qcow2GetExtensions(buf, buf_size, format) < 0)
return BACKING_STORE_INVALID;
return BACKING_STORE_OK;
}
static int
vmdk4GetBackingStore(char **res,
int *format,
const char *buf,
size_t buf_size)
{
static const char prefix[] = "parentFileNameHint=\"";
char *start, *end;
size_t len;
g_autofree char *desc = NULL;
desc = g_new0(char, VIR_STORAGE_MAX_HEADER);
*res = NULL;
/*
* Technically this should have been VMDK, since
* VMDK spec / VMware impl only support VMDK backed
* by VMDK. QEMU isn't following this though and
* does probing on VMDK backing files, hence we set
* AUTO
*/
*format = VIR_STORAGE_FILE_AUTO;
if (buf_size <= 0x200)
return BACKING_STORE_INVALID;
len = buf_size - 0x200;
if (len > VIR_STORAGE_MAX_HEADER)
len = VIR_STORAGE_MAX_HEADER;
memcpy(desc, buf + 0x200, len);
desc[len] = '\0';
start = strstr(desc, prefix);
if (start == NULL) {
*format = VIR_STORAGE_FILE_NONE;
return BACKING_STORE_OK;
}
start += strlen(prefix);
end = strchr(start, '"');
if (end == NULL)
return BACKING_STORE_INVALID;
if (end == start) {
*format = VIR_STORAGE_FILE_NONE;
return BACKING_STORE_OK;
}
*end = '\0';
*res = g_strdup(start);
return BACKING_STORE_OK;
}
static int
qedGetBackingStore(char **res,
int *format,
const char *buf,
size_t buf_size)
{
unsigned long long flags;
unsigned long offset, size;
*res = NULL;
/* Check if this image has a backing file */
if (buf_size < QED_HDR_FEATURES_OFFSET+8)
return BACKING_STORE_INVALID;
flags = virReadBufInt64LE(buf + QED_HDR_FEATURES_OFFSET);
if (!(flags & QED_F_BACKING_FILE)) {
*format = VIR_STORAGE_FILE_NONE;
return BACKING_STORE_OK;
}
/* Parse the backing file */
if (buf_size < QED_HDR_BACKING_FILE_OFFSET+8)
return BACKING_STORE_INVALID;
offset = virReadBufInt32LE(buf + QED_HDR_BACKING_FILE_OFFSET);
if (offset > buf_size)
return BACKING_STORE_INVALID;
size = virReadBufInt32LE(buf + QED_HDR_BACKING_FILE_SIZE);
if (size == 0)
return BACKING_STORE_OK;
if (offset + size > buf_size || offset + size < offset)
return BACKING_STORE_INVALID;
*res = g_new0(char, size + 1);
memcpy(*res, buf + offset, size);
(*res)[size] = '\0';
if (flags & QED_F_BACKING_FORMAT_NO_PROBE)
*format = VIR_STORAGE_FILE_RAW;
else
*format = VIR_STORAGE_FILE_AUTO_SAFE;
return BACKING_STORE_OK;
}
static bool
virStorageFileMatchesMagic(int magicOffset,
const char *magic,
char *buf,
size_t buflen)
{
int mlen;
if (magic == NULL)
return false;
/* Validate magic data */
mlen = strlen(magic);
if (magicOffset + mlen > buflen)
return false;
if (memcmp(buf + magicOffset, magic, mlen) != 0)
return false;
return true;
}
static bool
virStorageFileMatchesVersion(int versionOffset,
int versionSize,
const int *versionNumbers,
int endian,
char *buf,
size_t buflen)
{
int version;
size_t i;
/* Validate version number info */
if (versionOffset == -1)
return false;
/* -2 == non-versioned file format, so trivially match */
if (versionOffset == -2)
return true;
/* A positive versionOffset, requires using a valid versionSize */
if (versionSize != 2 && versionSize != 4)
return false;
if ((versionOffset + versionSize) > buflen)
return false;
if (endian == LV_LITTLE_ENDIAN) {
if (versionSize == 4)
version = virReadBufInt32LE(buf +
versionOffset);
else
version = virReadBufInt16LE(buf +
versionOffset);
} else {
if (versionSize == 4)
version = virReadBufInt32BE(buf +
versionOffset);
else
version = virReadBufInt16BE(buf +
versionOffset);
}
for (i = 0;
i < FILE_TYPE_VERSIONS_LAST && versionNumbers[i];
i++) {
VIR_DEBUG("Compare detected version %d vs one of the expected versions %d",
version, versionNumbers[i]);
if (version == versionNumbers[i])
return true;
}
return false;
}
static int
virStorageFileProbeFormatFromBuf(const char *path,
char *buf,
size_t buflen)
{
int format = VIR_STORAGE_FILE_RAW;
size_t i;
int possibleFormat = VIR_STORAGE_FILE_RAW;
VIR_DEBUG("path=%s, buf=%p, buflen=%zu", path, buf, buflen);
/* First check file magic */
for (i = 0; i < VIR_STORAGE_FILE_LAST; i++) {
if (virStorageFileMatchesMagic(fileTypeInfo[i].magicOffset,
fileTypeInfo[i].magic,
buf, buflen)) {
if (!virStorageFileMatchesVersion(fileTypeInfo[i].versionOffset,
fileTypeInfo[i].versionSize,
fileTypeInfo[i].versionNumbers,
fileTypeInfo[i].endian,
buf, buflen)) {
possibleFormat = i;
continue;
}
format = i;
goto cleanup;
}
}
if (possibleFormat != VIR_STORAGE_FILE_RAW)
VIR_WARN("File %s matches %s magic, but version is wrong. "
"Please report new version to libvir-list@redhat.com",
path, virStorageFileFormatTypeToString(possibleFormat));
cleanup:
VIR_DEBUG("format=%d", format);
return format;
}
static int
qcow2GetFeatures(virBitmapPtr *features,
int format,
char *buf,
ssize_t len)
{
int version = -1;
virBitmapPtr feat = NULL;
uint64_t bits;
size_t i;
version = virReadBufInt32BE(buf + fileTypeInfo[format].versionOffset);
if (version == 2)
return 0;
if (len < QCOW2v3_HDR_SIZE)
return -1;
feat = virBitmapNew(VIR_STORAGE_FILE_FEATURE_LAST);
/* todo: check for incompatible or autoclear features? */
bits = virReadBufInt64BE(buf + QCOW2v3_HDR_FEATURES_COMPATIBLE);
for (i = 0; i < QCOW2_COMPATIBLE_FEATURE_LAST; i++) {
if (bits & ((uint64_t) 1 << i))
ignore_value(virBitmapSetBit(feat, qcow2CompatibleFeatureArray[i]));
}
*features = feat;
return 0;
}
static bool
virStorageFileHasEncryptionFormat(const struct FileEncryptionInfo *info,
char *buf,
size_t len)
{
if (!info->magic && info->modeOffset == -1)
return false; /* Shouldn't happen - expect at least one */
if (info->magic) {
if (!virStorageFileMatchesMagic(info->magicOffset,
info->magic,
buf, len))
return false;
if (info->versionOffset != -1 &&
!virStorageFileMatchesVersion(info->versionOffset,
info->versionSize,
info->versionNumbers,
info->endian,
buf, len))
return false;
return true;
} else if (info->modeOffset != -1) {
int crypt_format;
if (info->modeOffset >= len)
return false;
crypt_format = virReadBufInt32BE(buf + info->modeOffset);
if (crypt_format != info->modeValue)
return false;
return true;
} else {
return false;
}
}
static int
virStorageFileGetEncryptionPayloadOffset(const struct FileEncryptionInfo *info,
char *buf)
{
int payload_offset = -1;
if (info->payloadOffset != -1) {
if (info->endian == LV_LITTLE_ENDIAN)
payload_offset = virReadBufInt32LE(buf + info->payloadOffset);
else
payload_offset = virReadBufInt32BE(buf + info->payloadOffset);
}
return payload_offset;
}
/* Given a header in BUF with length LEN, as parsed from the storage file
* assuming it has the given FORMAT, populate information into META
* with information about the file and its backing store. Return format
* of the backing store as BACKING_FORMAT. PATH and FORMAT have to be
* pre-populated in META.
*
* Note that this function may be called repeatedly on @meta, so it must
* clean up any existing allocated memory which would be overwritten.
*/
int
virStorageFileProbeGetMetadata(virStorageSourcePtr meta,
char *buf,
size_t len)
{
int format;
size_t i;
VIR_DEBUG("path=%s, buf=%p, len=%zu, meta->format=%d",
meta->path, buf, len, meta->format);
if (meta->format == VIR_STORAGE_FILE_AUTO)
meta->format = virStorageFileProbeFormatFromBuf(meta->path, buf, len);
if (meta->format <= VIR_STORAGE_FILE_NONE ||
meta->format >= VIR_STORAGE_FILE_LAST) {
virReportSystemError(EINVAL, _("unknown storage file meta->format %d"),
meta->format);
return -1;
}
if (fileTypeInfo[meta->format].cryptInfo != NULL) {
for (i = 0; fileTypeInfo[meta->format].cryptInfo[i].format != 0; i++) {
if (virStorageFileHasEncryptionFormat(&fileTypeInfo[meta->format].cryptInfo[i],
buf, len)) {
int expt_fmt = fileTypeInfo[meta->format].cryptInfo[i].format;
if (!meta->encryption) {
meta->encryption = g_new0(virStorageEncryption, 1);
meta->encryption->format = expt_fmt;
} else {
if (meta->encryption->format != expt_fmt) {
virReportError(VIR_ERR_XML_ERROR,
_("encryption format %d doesn't match "
"expected format %d"),
meta->encryption->format, expt_fmt);
return -1;
}
}
meta->encryption->payload_offset =
virStorageFileGetEncryptionPayloadOffset(&fileTypeInfo[meta->format].cryptInfo[i], buf);
}
}
}
/* XXX we should consider moving virStorageBackendUpdateVolInfo
* code into this method, for non-magic files
*/
if (!fileTypeInfo[meta->format].magic)
return 0;
/* Optionally extract capacity from file */
if (fileTypeInfo[meta->format].sizeOffset != -1) {
if ((fileTypeInfo[meta->format].sizeOffset + 8) > len)
return 0;
if (fileTypeInfo[meta->format].endian == LV_LITTLE_ENDIAN)
meta->capacity = virReadBufInt64LE(buf +
fileTypeInfo[meta->format].sizeOffset);
else
meta->capacity = virReadBufInt64BE(buf +
fileTypeInfo[meta->format].sizeOffset);
/* Avoid unlikely, but theoretically possible overflow */
if (meta->capacity > (ULLONG_MAX /
fileTypeInfo[meta->format].sizeMultiplier))
return 0;
meta->capacity *= fileTypeInfo[meta->format].sizeMultiplier;
}
VIR_FREE(meta->backingStoreRaw);
if (fileTypeInfo[meta->format].getBackingStore != NULL) {
int store = fileTypeInfo[meta->format].getBackingStore(&meta->backingStoreRaw,
&format,
buf, len);
meta->backingStoreRawFormat = format;
if (store == BACKING_STORE_INVALID)
return 0;
if (store == BACKING_STORE_ERROR)
return -1;
}
virBitmapFree(meta->features);
meta->features = NULL;
if (fileTypeInfo[meta->format].getFeatures != NULL &&
fileTypeInfo[meta->format].getFeatures(&meta->features, meta->format, buf, len) < 0)
return -1;
VIR_FREE(meta->compat);
if (meta->format == VIR_STORAGE_FILE_QCOW2 && meta->features)
meta->compat = g_strdup("1.1");
return 0;
}
/**
* virStorageFileProbeFormat:
*
* Probe for the format of 'path', returning the detected
* disk format.
*
* Callers are advised never to trust the returned 'format'
* unless it is listed as VIR_STORAGE_FILE_RAW, since a
* malicious guest can turn a raw file into any other non-raw
* format at will.
*
* Best option: Don't use this function
*/
int
virStorageFileProbeFormat(const char *path, uid_t uid, gid_t gid)
{
struct stat sb;
ssize_t len = VIR_STORAGE_MAX_HEADER;
VIR_AUTOCLOSE fd = -1;
g_autofree char *header = NULL;
if ((fd = virFileOpenAs(path, O_RDONLY, 0, uid, gid, 0)) < 0) {
virReportSystemError(-fd, _("Failed to open file '%s'"), path);
return -1;
}
if (fstat(fd, &sb) < 0) {
virReportSystemError(errno, _("cannot stat file '%s'"), path);
return -1;
}
/* No header to probe for directories */
if (S_ISDIR(sb.st_mode))
return VIR_STORAGE_FILE_DIR;
if (lseek(fd, 0, SEEK_SET) == (off_t)-1) {
virReportSystemError(errno, _("cannot set to start of '%s'"), path);
return -1;
}
if ((len = virFileReadHeaderFD(fd, len, &header)) < 0) {
virReportSystemError(errno, _("cannot read header '%s'"), path);
return -1;
}
return virStorageFileProbeFormatFromBuf(path, header, len);
}