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libvirt/src/util/storage_file.c
Eric Blake 54456cc0fd storage: avoid mishandling backing store > 2GB 
Detected by Coverity.  The code was doing math on shifted unsigned
char (which promotes to int), then promoting that to unsigned long
during assignment to size.  On 64-bit platforms, this risks sign
extending values of size > 2GiB.  Bug present since commit
489fd3 (v0.6.0).

I'm not sure if a specially-crafted bogus qcow2 image could
exploit this, although it's probably not possible, since we
were already checking for the computed results being within
range of our fixed-size buffer.

* src/util/storage_file.c (qcowXGetBackingStore): Avoid sign
extension.
2011-06-08 05:18:46 -06:00

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/*
* storage_file.c: file utility functions for FS storage backend
*
* Copyright (C) 2007-2011 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, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Author: Daniel P. Berrange <berrange@redhat.com>
*/
#include <config.h>
#include "storage_file.h"
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#ifdef __linux__
# if HAVE_LINUX_MAGIC_H
# include <linux/magic.h>
# endif
# include <sys/statfs.h>
#endif
#include "dirname.h"
#include "memory.h"
#include "virterror_internal.h"
#include "logging.h"
#include "files.h"
#define VIR_FROM_THIS VIR_FROM_STORAGE
VIR_ENUM_IMPL(virStorageFileFormat,
VIR_STORAGE_FILE_LAST,
"raw", "dir", "bochs",
"cloop", "cow", "dmg", "iso",
"qcow", "qcow2", "qed", "vmdk", "vpc")
enum lv_endian {
LV_LITTLE_ENDIAN = 1, /* 1234 */
LV_BIG_ENDIAN /* 4321 */
};
enum {
BACKING_STORE_OK,
BACKING_STORE_INVALID,
BACKING_STORE_ERROR,
};
/* Either 'magic' or 'extension' *must* be provided */
struct FileTypeInfo {
const char *magic; /* Optional string of file magic
* to check at head of file */
const char *extension; /* Optional file extension to check */
enum lv_endian endian; /* Endianness of file format */
int versionOffset; /* Byte offset from start of file
* where we find version number,
* -1 to skip version test */
int versionNumber; /* Version number to validate */
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_* */
int qcowCryptOffset; /* Byte offset from start of file
* where to find encryption mode,
* -1 if encryption is not used */
int (*getBackingStore)(char **res, int *format,
const unsigned char *buf, size_t buf_size);
};
static int cowGetBackingStore(char **, int *,
const unsigned char *, size_t);
static int qcow1GetBackingStore(char **, int *,
const unsigned char *, size_t);
static int qcow2GetBackingStore(char **, int *,
const unsigned char *, size_t);
static int vmdk4GetBackingStore(char **, int *,
const unsigned char *, size_t);
static int
qedGetBackingStore(char **, int *, const unsigned 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)
#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 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
/* VMDK needs at least this to find backing store,
* other formats need less */
#define STORAGE_MAX_HEAD (20*512)
static struct FileTypeInfo const fileTypeInfo[] = {
[VIR_STORAGE_FILE_RAW] = { NULL, NULL, LV_LITTLE_ENDIAN, -1, 0, 0, 0, 0, 0, NULL },
[VIR_STORAGE_FILE_DIR] = { NULL, NULL, LV_LITTLE_ENDIAN, -1, 0, 0, 0, 0, 0, NULL },
[VIR_STORAGE_FILE_BOCHS] = {
/*"Bochs Virtual HD Image", */ /* Untested */ NULL,
NULL,
LV_LITTLE_ENDIAN, 64, 0x20000,
32+16+16+4+4+4+4+4, 8, 1, -1, NULL
},
[VIR_STORAGE_FILE_CLOOP] = {
/*"#!/bin/sh\n#V2.0 Format\nmodprobe cloop file=$0 && mount -r -t iso9660 /dev/cloop $1\n", */ /* Untested */ NULL,
NULL,
LV_LITTLE_ENDIAN, -1, 0,
-1, 0, 0, -1, NULL
},
[VIR_STORAGE_FILE_COW] = {
"OOOM", NULL,
LV_BIG_ENDIAN, 4, 2,
4+4+1024+4, 8, 1, -1, cowGetBackingStore
},
[VIR_STORAGE_FILE_DMG] = {
NULL, /* XXX QEMU says there's no magic for dmg, but we should check... */
".dmg",
0, -1, 0,
-1, 0, 0, -1, NULL
},
[VIR_STORAGE_FILE_ISO] = {
NULL, /* XXX there's probably some magic for iso we can validate too... */
".iso",
0, -1, 0,
-1, 0, 0, -1, NULL
},
[VIR_STORAGE_FILE_QCOW] = {
"QFI", NULL,
LV_BIG_ENDIAN, 4, 1,
QCOWX_HDR_IMAGE_SIZE, 8, 1, QCOW1_HDR_CRYPT, qcow1GetBackingStore,
},
[VIR_STORAGE_FILE_QCOW2] = {
"QFI", NULL,
LV_BIG_ENDIAN, 4, 2,
QCOWX_HDR_IMAGE_SIZE, 8, 1, QCOW2_HDR_CRYPT, qcow2GetBackingStore,
},
[VIR_STORAGE_FILE_QED] = {
/* http://wiki.qemu.org/Features/QED */
"QED\0", NULL,
LV_LITTLE_ENDIAN, -1, -1,
QED_HDR_IMAGE_SIZE, 8, 1, -1, qedGetBackingStore,
},
[VIR_STORAGE_FILE_VMDK] = {
"KDMV", NULL,
LV_LITTLE_ENDIAN, 4, 1,
4+4+4, 8, 512, -1, vmdk4GetBackingStore
},
[VIR_STORAGE_FILE_VPC] = {
"conectix", NULL,
LV_BIG_ENDIAN, 12, 0x10000,
8 + 4 + 4 + 8 + 4 + 4 + 2 + 2 + 4, 8, 1, -1, NULL
},
};
verify(ARRAY_CARDINALITY(fileTypeInfo) == VIR_STORAGE_FILE_LAST);
static int
cowGetBackingStore(char **res,
int *format,
const unsigned 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] */
return BACKING_STORE_OK;
*res = strndup ((const char*)buf + 4+4, COW_FILENAME_MAXLEN);
if (*res == NULL) {
virReportOOMError();
return BACKING_STORE_ERROR;
}
return BACKING_STORE_OK;
}
static int
qcow2GetBackingStoreFormat(int *format,
const unsigned char *buf,
size_t buf_size,
size_t extension_start,
size_t extension_end)
{
size_t offset = extension_start;
/*
* 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.
*/
while (offset < (buf_size-8) &&
offset < (extension_end-8)) {
unsigned int magic =
(buf[offset] << 24) +
(buf[offset+1] << 16) +
(buf[offset+2] << 8) +
(buf[offset+3]);
unsigned int len =
(buf[offset+4] << 24) +
(buf[offset+5] << 16) +
(buf[offset+6] << 8) +
(buf[offset+7]);
offset += 8;
if ((offset + len) < offset)
break;
if ((offset + len) > buf_size)
break;
switch (magic) {
case QCOW2_HDR_EXTENSION_END:
goto done;
case QCOW2_HDR_EXTENSION_BACKING_FORMAT:
if (buf[offset+len] != '\0')
break;
*format = virStorageFileFormatTypeFromString(
((const char *)buf)+offset);
break;
}
offset += len;
}
done:
return 0;
}
static int
qcowXGetBackingStore(char **res,
int *format,
const unsigned char *buf,
size_t buf_size,
bool isQCow2)
{
unsigned long long offset;
unsigned int size;
*res = NULL;
if (format)
*format = VIR_STORAGE_FILE_AUTO;
if (buf_size < QCOWX_HDR_BACKING_FILE_OFFSET+8+4)
return BACKING_STORE_INVALID;
offset = (((unsigned long long)buf[QCOWX_HDR_BACKING_FILE_OFFSET] << 56)
| ((unsigned long long)buf[QCOWX_HDR_BACKING_FILE_OFFSET+1] << 48)
| ((unsigned long long)buf[QCOWX_HDR_BACKING_FILE_OFFSET+2] << 40)
| ((unsigned long long)buf[QCOWX_HDR_BACKING_FILE_OFFSET+3] << 32)
| ((unsigned long long)buf[QCOWX_HDR_BACKING_FILE_OFFSET+4] << 24)
| ((unsigned long long)buf[QCOWX_HDR_BACKING_FILE_OFFSET+5] << 16)
| ((unsigned long long)buf[QCOWX_HDR_BACKING_FILE_OFFSET+6] << 8)
| buf[QCOWX_HDR_BACKING_FILE_OFFSET+7]); /* QCowHeader.backing_file_offset */
if (offset > buf_size)
return BACKING_STORE_INVALID;
size = ((buf[QCOWX_HDR_BACKING_FILE_SIZE] << 24)
| (buf[QCOWX_HDR_BACKING_FILE_SIZE+1] << 16)
| (buf[QCOWX_HDR_BACKING_FILE_SIZE+2] << 8)
| buf[QCOWX_HDR_BACKING_FILE_SIZE+3]); /* QCowHeader.backing_file_size */
if (size == 0)
return BACKING_STORE_OK;
if (offset + size > buf_size || offset + size < offset)
return BACKING_STORE_INVALID;
if (size + 1 == 0)
return BACKING_STORE_INVALID;
if (VIR_ALLOC_N(*res, size + 1) < 0) {
virReportOOMError();
return BACKING_STORE_ERROR;
}
memcpy(*res, buf + offset, size);
(*res)[size] = '\0';
/*
* 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)
*/
if (isQCow2)
qcow2GetBackingStoreFormat(format, buf, buf_size, QCOW2_HDR_TOTAL_SIZE, offset);
return BACKING_STORE_OK;
}
static int
qcow1GetBackingStore(char **res,
int *format,
const unsigned char *buf,
size_t buf_size)
{
/* QCow1 doesn't have the extensions capability
* used to store backing format */
*format = VIR_STORAGE_FILE_AUTO;
return qcowXGetBackingStore(res, NULL, buf, buf_size, false);
}
static int
qcow2GetBackingStore(char **res,
int *format,
const unsigned char *buf,
size_t buf_size)
{
return qcowXGetBackingStore(res, format, buf, buf_size, true);
}
static int
vmdk4GetBackingStore(char **res,
int *format,
const unsigned char *buf,
size_t buf_size)
{
static const char prefix[] = "parentFileNameHint=\"";
char *desc, *start, *end;
size_t len;
int ret = BACKING_STORE_ERROR;
if (VIR_ALLOC_N(desc, STORAGE_MAX_HEAD + 1) < 0) {
virReportOOMError();
goto cleanup;
}
*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) {
ret = BACKING_STORE_INVALID;
goto cleanup;
}
len = buf_size - 0x200;
if (len > STORAGE_MAX_HEAD)
len = STORAGE_MAX_HEAD;
memcpy(desc, buf + 0x200, len);
desc[len] = '\0';
start = strstr(desc, prefix);
if (start == NULL) {
ret = BACKING_STORE_OK;
goto cleanup;
}
start += strlen(prefix);
end = strchr(start, '"');
if (end == NULL) {
ret = BACKING_STORE_INVALID;
goto cleanup;
}
if (end == start) {
ret = BACKING_STORE_OK;
goto cleanup;
}
*end = '\0';
*res = strdup(start);
if (*res == NULL) {
virReportOOMError();
goto cleanup;
}
ret = BACKING_STORE_OK;
cleanup:
VIR_FREE(desc);
return ret;
}
static unsigned long
qedGetHeaderUL(const unsigned char *loc)
{
return ( ((unsigned long)loc[3] << 24)
| ((unsigned long)loc[2] << 16)
| ((unsigned long)loc[1] << 8)
| ((unsigned long)loc[0] << 0));
}
static unsigned long long
qedGetHeaderULL(const unsigned char *loc)
{
return ( ((unsigned long long)loc[7] << 56)
| ((unsigned long long)loc[6] << 48)
| ((unsigned long long)loc[5] << 40)
| ((unsigned long long)loc[4] << 32)
| ((unsigned long long)loc[3] << 24)
| ((unsigned long long)loc[2] << 16)
| ((unsigned long long)loc[1] << 8)
| ((unsigned long long)loc[0] << 0));
}
static int
qedGetBackingStore(char **res,
int *format,
const unsigned 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 = qedGetHeaderULL(buf + QED_HDR_FEATURES_OFFSET);
if (!(flags & QED_F_BACKING_FILE))
return BACKING_STORE_OK;
/* Parse the backing file */
if (buf_size < QED_HDR_BACKING_FILE_OFFSET+8)
return BACKING_STORE_INVALID;
offset = qedGetHeaderUL(buf + QED_HDR_BACKING_FILE_OFFSET);
if (offset > buf_size)
return BACKING_STORE_INVALID;
size = qedGetHeaderUL(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;
if (VIR_ALLOC_N(*res, size + 1) < 0) {
virReportOOMError();
return BACKING_STORE_ERROR;
}
memcpy(*res, buf + offset, size);
(*res)[size] = '\0';
if (format) {
if (flags & QED_F_BACKING_FORMAT_NO_PROBE)
*format = virStorageFileFormatTypeFromString("raw");
else
*format = VIR_STORAGE_FILE_AUTO_SAFE;
}
return BACKING_STORE_OK;
}
/**
* Return an absolute path corresponding to PATH, which is absolute or relative
* to the directory containing BASE_FILE, or NULL on error
*/
static char *
absolutePathFromBaseFile(const char *base_file, const char *path)
{
char *res;
size_t d_len = dir_len (base_file);
/* If path is already absolute, or if dirname(base_file) is ".",
just return a copy of path. */
if (*path == '/' || d_len == 0)
return strdup(path);
/* Ensure that the following cast-to-int is valid. */
if (d_len > INT_MAX)
return NULL;
virAsprintf(&res, "%.*s/%s", (int) d_len, base_file, path);
return res;
}
static bool
virStorageFileMatchesMagic(int format,
unsigned char *buf,
size_t buflen)
{
int mlen;
if (fileTypeInfo[format].magic == NULL)
return false;
/* Validate magic data */
mlen = strlen(fileTypeInfo[format].magic);
if (mlen > buflen)
return false;
if (memcmp(buf, fileTypeInfo[format].magic, mlen) != 0)
return false;
return true;
}
static bool
virStorageFileMatchesExtension(int format,
const char *path)
{
if (fileTypeInfo[format].extension == NULL)
return false;
if (virFileHasSuffix(path, fileTypeInfo[format].extension))
return true;
return false;
}
static bool
virStorageFileMatchesVersion(int format,
unsigned char *buf,
size_t buflen)
{
int version;
/* Validate version number info */
if (fileTypeInfo[format].versionOffset == -1)
return true;
if ((fileTypeInfo[format].versionOffset + 4) > buflen)
return false;
if (fileTypeInfo[format].endian == LV_LITTLE_ENDIAN) {
version =
(buf[fileTypeInfo[format].versionOffset+3] << 24) |
(buf[fileTypeInfo[format].versionOffset+2] << 16) |
(buf[fileTypeInfo[format].versionOffset+1] << 8) |
(buf[fileTypeInfo[format].versionOffset]);
} else {
version =
(buf[fileTypeInfo[format].versionOffset] << 24) |
(buf[fileTypeInfo[format].versionOffset+1] << 16) |
(buf[fileTypeInfo[format].versionOffset+2] << 8) |
(buf[fileTypeInfo[format].versionOffset+3]);
}
if (version != fileTypeInfo[format].versionNumber)
return false;
return true;
}
static bool
virBackingStoreIsFile(const char *backing)
{
/* Backing store is a network block device */
if (STRPREFIX(backing, "nbd:"))
return false;
return true;
}
static int
virStorageFileGetMetadataFromBuf(int format,
const char *path,
unsigned char *buf,
size_t buflen,
virStorageFileMetadata *meta)
{
/* XXX we should consider moving virStorageBackendUpdateVolInfo
* code into this method, for non-magic files
*/
if (!fileTypeInfo[format].magic) {
return 0;
}
/* Optionally extract capacity from file */
if (fileTypeInfo[format].sizeOffset != -1) {
if ((fileTypeInfo[format].sizeOffset + 8) > buflen)
return 1;
if (fileTypeInfo[format].endian == LV_LITTLE_ENDIAN) {
meta->capacity =
((unsigned long long)buf[fileTypeInfo[format].sizeOffset+7] << 56) |
((unsigned long long)buf[fileTypeInfo[format].sizeOffset+6] << 48) |
((unsigned long long)buf[fileTypeInfo[format].sizeOffset+5] << 40) |
((unsigned long long)buf[fileTypeInfo[format].sizeOffset+4] << 32) |
((unsigned long long)buf[fileTypeInfo[format].sizeOffset+3] << 24) |
((unsigned long long)buf[fileTypeInfo[format].sizeOffset+2] << 16) |
((unsigned long long)buf[fileTypeInfo[format].sizeOffset+1] << 8) |
((unsigned long long)buf[fileTypeInfo[format].sizeOffset]);
} else {
meta->capacity =
((unsigned long long)buf[fileTypeInfo[format].sizeOffset] << 56) |
((unsigned long long)buf[fileTypeInfo[format].sizeOffset+1] << 48) |
((unsigned long long)buf[fileTypeInfo[format].sizeOffset+2] << 40) |
((unsigned long long)buf[fileTypeInfo[format].sizeOffset+3] << 32) |
((unsigned long long)buf[fileTypeInfo[format].sizeOffset+4] << 24) |
((unsigned long long)buf[fileTypeInfo[format].sizeOffset+5] << 16) |
((unsigned long long)buf[fileTypeInfo[format].sizeOffset+6] << 8) |
((unsigned long long)buf[fileTypeInfo[format].sizeOffset+7]);
}
/* Avoid unlikely, but theoretically possible overflow */
if (meta->capacity > (ULLONG_MAX / fileTypeInfo[format].sizeMultiplier))
return 1;
meta->capacity *= fileTypeInfo[format].sizeMultiplier;
}
if (fileTypeInfo[format].qcowCryptOffset != -1) {
int crypt_format;
crypt_format =
(buf[fileTypeInfo[format].qcowCryptOffset] << 24) |
(buf[fileTypeInfo[format].qcowCryptOffset+1] << 16) |
(buf[fileTypeInfo[format].qcowCryptOffset+2] << 8) |
(buf[fileTypeInfo[format].qcowCryptOffset+3]);
meta->encrypted = crypt_format != 0;
}
if (fileTypeInfo[format].getBackingStore != NULL) {
char *backing;
int backingFormat;
int ret = fileTypeInfo[format].getBackingStore(&backing,
&backingFormat,
buf, buflen);
if (ret == BACKING_STORE_INVALID)
return 1;
if (ret == BACKING_STORE_ERROR)
return -1;
meta->backingStoreIsFile = false;
if (backing != NULL) {
if (virBackingStoreIsFile(backing)) {
meta->backingStoreIsFile = true;
meta->backingStore = absolutePathFromBaseFile(path, backing);
} else {
meta->backingStore = strdup(backing);
}
VIR_FREE(backing);
if (meta->backingStore == NULL) {
virReportOOMError();
return -1;
}
meta->backingStoreFormat = backingFormat;
} else {
meta->backingStore = NULL;
meta->backingStoreFormat = VIR_STORAGE_FILE_AUTO;
}
}
return 0;
}
static int
virStorageFileProbeFormatFromBuf(const char *path,
unsigned char *buf,
size_t buflen)
{
int format = VIR_STORAGE_FILE_RAW;
int i;
/* First check file magic */
for (i = 0 ; i < VIR_STORAGE_FILE_LAST ; i++) {
if (virStorageFileMatchesMagic(i, buf, buflen) &&
virStorageFileMatchesVersion(i, buf, buflen)) {
format = i;
goto cleanup;
}
}
/* No magic, so check file extension */
for (i = 0 ; i < VIR_STORAGE_FILE_LAST ; i++) {
if (virStorageFileMatchesExtension(i, path)) {
format = i;
goto cleanup;
}
}
cleanup:
return format;
}
/**
* virStorageFileProbeFormatFromFD:
*
* Probe for the format of 'fd' (which is an open file descriptor
* pointing to '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 file into any other non-raw
* format at will.
*
* Best option: Don't use this function
*/
int
virStorageFileProbeFormatFromFD(const char *path, int fd)
{
unsigned char *head;
ssize_t len = STORAGE_MAX_HEAD;
int ret = -1;
struct stat sb;
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 (VIR_ALLOC_N(head, len) < 0) {
virReportOOMError();
return -1;
}
if (lseek(fd, 0, SEEK_SET) == (off_t)-1) {
virReportSystemError(errno, _("cannot set to start of '%s'"), path);
goto cleanup;
}
if ((len = read(fd, head, len)) < 0) {
virReportSystemError(errno, _("cannot read header '%s'"), path);
goto cleanup;
}
ret = virStorageFileProbeFormatFromBuf(path, head, len);
cleanup:
VIR_FREE(head);
return ret;
}
/**
* 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)
{
int fd, ret;
if ((fd = open(path, O_RDONLY)) < 0) {
virReportSystemError(errno, _("cannot open file '%s'"), path);
return -1;
}
ret = virStorageFileProbeFormatFromFD(path, fd);
VIR_FORCE_CLOSE(fd);
return ret;
}
/**
* virStorageFileGetMetadataFromFD:
*
* Extract metadata about the storage volume with the specified
* image format. If image format is VIR_STORAGE_FILE_AUTO, it
* will probe to automatically identify the format.
*
* Callers are advised never to use VIR_STORAGE_FILE_AUTO as a
* format, since a malicious guest can turn a raw file into any
* other non-raw format at will.
*
* If the returned meta.backingStoreFormat is VIR_STORAGE_FILE_AUTO
* it indicates the image didn't specify an explicit format for its
* backing store. Callers are advised against probing for the
* backing store format in this case.
*/
int
virStorageFileGetMetadataFromFD(const char *path,
int fd,
int format,
virStorageFileMetadata *meta)
{
unsigned char *head = NULL;
ssize_t len = STORAGE_MAX_HEAD;
int ret = -1;
struct stat sb;
memset(meta, 0, sizeof (*meta));
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 0;
}
if (lseek(fd, 0, SEEK_SET) == (off_t)-1) {
virReportSystemError(errno, _("cannot seek to start of '%s'"), path);
return -1;
}
if (VIR_ALLOC_N(head, len) < 0) {
virReportOOMError();
return -1;
}
if ((len = read(fd, head, len)) < 0) {
virReportSystemError(errno, _("cannot read header '%s'"), path);
goto cleanup;
}
if (format == VIR_STORAGE_FILE_AUTO)
format = virStorageFileProbeFormatFromBuf(path, head, len);
if (format < 0 ||
format >= VIR_STORAGE_FILE_LAST) {
virReportSystemError(EINVAL, _("unknown storage file format %d"),
format);
goto cleanup;
}
ret = virStorageFileGetMetadataFromBuf(format, path, head, len, meta);
cleanup:
VIR_FREE(head);
return ret;
}
/**
* virStorageFileGetMetadata:
*
* Extract metadata about the storage volume with the specified
* image format. If image format is VIR_STORAGE_FILE_AUTO, it
* will probe to automatically identify the format.
*
* Callers are advised never to use VIR_STORAGE_FILE_AUTO as a
* format, since a malicious guest can turn a raw file into any
* other non-raw format at will.
*
* If the returned meta.backingStoreFormat is VIR_STORAGE_FILE_AUTO
* it indicates the image didn't specify an explicit format for its
* backing store. Callers are advised against probing for the
* backing store format in this case.
*/
int
virStorageFileGetMetadata(const char *path,
int format,
virStorageFileMetadata *meta)
{
int fd, ret;
if ((fd = open(path, O_RDONLY)) < 0) {
virReportSystemError(errno, _("cannot open file '%s'"), path);
return -1;
}
ret = virStorageFileGetMetadataFromFD(path, fd, format, meta);
VIR_FORCE_CLOSE(fd);
return ret;
}
#ifdef __linux__
# ifndef NFS_SUPER_MAGIC
# define NFS_SUPER_MAGIC 0x6969
# endif
# ifndef OCFS2_SUPER_MAGIC
# define OCFS2_SUPER_MAGIC 0x7461636f
# endif
# ifndef GFS2_MAGIC
# define GFS2_MAGIC 0x01161970
# endif
# ifndef AFS_FS_MAGIC
# define AFS_FS_MAGIC 0x6B414653
# endif
int virStorageFileIsSharedFSType(const char *path,
int fstypes)
{
char *dirpath, *p;
struct statfs sb;
int statfs_ret;
if ((dirpath = strdup(path)) == NULL) {
virReportOOMError();
return -1;
}
do {
/* Try less and less of the path until we get to a
* directory we can stat. Even if we don't have 'x'
* permission on any directory in the path on the NFS
* server (assuming it's NFS), we will be able to stat the
* mount point, and that will properly tell us if the
* fstype is NFS.
*/
if ((p = strrchr(dirpath, '/')) == NULL) {
virReportSystemError(EINVAL,
_("Invalid relative path '%s'"), path);
VIR_FREE(dirpath);
return -1;
}
if (p == dirpath)
*(p+1) = '\0';
else
*p = '\0';
statfs_ret = statfs(dirpath, &sb);
} while ((statfs_ret < 0) && (p != dirpath));
VIR_FREE(dirpath);
if (statfs_ret < 0) {
virReportSystemError(errno,
_("cannot determine filesystem for '%s'"),
path);
return -1;
}
VIR_DEBUG("Check if path %s with FS magic %lld is shared",
path, (long long int)sb.f_type);
if ((fstypes & VIR_STORAGE_FILE_SHFS_NFS) &&
(sb.f_type == NFS_SUPER_MAGIC))
return 1;
if ((fstypes & VIR_STORAGE_FILE_SHFS_GFS2) &&
(sb.f_type == GFS2_MAGIC))
return 1;
if ((fstypes & VIR_STORAGE_FILE_SHFS_OCFS) &&
(sb.f_type == OCFS2_SUPER_MAGIC))
return 1;
if ((fstypes & VIR_STORAGE_FILE_SHFS_AFS) &&
(sb.f_type == AFS_FS_MAGIC))
return 1;
return 0;
}
#else
int virStorageFileIsSharedFSType(const char *path ATTRIBUTE_UNUSED,
int fstypes ATTRIBUTE_UNUSED)
{
/* XXX implement me :-) */
return 0;
}
#endif
int virStorageFileIsSharedFS(const char *path)
{
return virStorageFileIsSharedFSType(path,
VIR_STORAGE_FILE_SHFS_NFS |
VIR_STORAGE_FILE_SHFS_GFS2 |
VIR_STORAGE_FILE_SHFS_OCFS |
VIR_STORAGE_FILE_SHFS_AFS);
}
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