block: VHDX endian fixes

This patch contains several changes for endian conversion fixes for
VHDX, particularly for big-endian machines (multibyte values in VHDX are
all on disk in LE format).

Tests were done with existing qemu-iotests on an IBM POWER7 (8406-71Y).
This includes sample images created by Hyper-V, both with dirty logs and
without.

In addition, VHDX image files created (and written to) on a BE machine
were tested on a LE machine, and vice-versa.

Reported-by: Markus Armburster <armbru@redhat.com>
Reported-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Jeff Cody <jcody@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

4 files changed, 88 insertions, 56 deletions

diff --git a/block/vhdx-endian.c b/block/vhdx-endian.c
index fe879ed995..0640d3f4a9 100644
--- a/block/vhdx-endian.c
+++ b/block/vhdx-endian.c
@@ -82,8 +82,6 @@ void vhdx_log_desc_le_import(VHDXLogDescriptor *d)
     assert(d != NULL);
 
     le32_to_cpus(&d->signature);
-    le32_to_cpus(&d->trailing_bytes);
-    le64_to_cpus(&d->leading_bytes);
     le64_to_cpus(&d->file_offset);
     le64_to_cpus(&d->sequence_number);
 }
@@ -99,6 +97,15 @@ void vhdx_log_desc_le_export(VHDXLogDescriptor *d)
     cpu_to_le64s(&d->sequence_number);
 }
 
+void vhdx_log_data_le_import(VHDXLogDataSector *d)
+{
+    assert(d != NULL);
+
+    le32_to_cpus(&d->data_signature);
+    le32_to_cpus(&d->sequence_high);
+    le32_to_cpus(&d->sequence_low);
+}
+
 void vhdx_log_data_le_export(VHDXLogDataSector *d)
 {
     assert(d != NULL);
diff --git a/block/vhdx-log.c b/block/vhdx-log.c
index 7c2630d659..0088be8747 100644
--- a/block/vhdx-log.c
+++ b/block/vhdx-log.c
@@ -84,6 +84,7 @@ static int vhdx_log_peek_hdr(BlockDriverState *bs, VHDXLogEntries *log,
     if (ret < 0) {
         goto exit;
     }
+    vhdx_log_entry_hdr_le_import(hdr);
 
 exit:
     return ret;
@@ -211,7 +212,7 @@ static bool vhdx_log_hdr_is_valid(VHDXLogEntries *log, VHDXLogEntryHeader *hdr,
 {
     int valid = false;
 
-    if (memcmp(&hdr->signature, "loge", 4)) {
+    if (hdr->signature != VHDX_LOG_SIGNATURE) {
         goto exit;
     }
 
@@ -275,12 +276,12 @@ static bool vhdx_log_desc_is_valid(VHDXLogDescriptor *desc,
         goto exit;
     }
 
-    if (!memcmp(&desc->signature, "zero", 4)) {
+    if (desc->signature == VHDX_LOG_ZERO_SIGNATURE) {
         if (desc->zero_length % VHDX_LOG_SECTOR_SIZE == 0) {
             /* valid */
             ret = true;
         }
-    } else if (!memcmp(&desc->signature, "desc", 4)) {
+    } else if (desc->signature == VHDX_LOG_DESC_SIGNATURE) {
             /* valid */
             ret = true;
     }
@@ -327,13 +328,15 @@ static int vhdx_compute_desc_sectors(uint32_t desc_cnt)
  * passed into this function. Each descriptor will also be validated,
  * and error returned if any are invalid. */
 static int vhdx_log_read_desc(BlockDriverState *bs, BDRVVHDXState *s,
-                              VHDXLogEntries *log, VHDXLogDescEntries **buffer)
+                              VHDXLogEntries *log, VHDXLogDescEntries **buffer,
+                              bool convert_endian)
 {
     int ret = 0;
     uint32_t desc_sectors;
     uint32_t sectors_read;
     VHDXLogEntryHeader hdr;
     VHDXLogDescEntries *desc_entries = NULL;
+    VHDXLogDescriptor desc;
     int i;
 
     assert(*buffer == NULL);
@@ -342,7 +345,7 @@ static int vhdx_log_read_desc(BlockDriverState *bs, BDRVVHDXState *s,
     if (ret < 0) {
         goto exit;
     }
-    vhdx_log_entry_hdr_le_import(&hdr);
+
     if (vhdx_log_hdr_is_valid(log, &hdr, s) == false) {
         ret = -EINVAL;
         goto exit;
@@ -363,12 +366,19 @@ static int vhdx_log_read_desc(BlockDriverState *bs, BDRVVHDXState *s,
 
     /* put in proper endianness, and validate each desc */
     for (i = 0; i < hdr.descriptor_count; i++) {
-        vhdx_log_desc_le_import(&desc_entries->desc[i]);
-        if (vhdx_log_desc_is_valid(&desc_entries->desc[i], &hdr) == false) {
+        desc = desc_entries->desc[i];
+        vhdx_log_desc_le_import(&desc);
+        if (convert_endian) {
+            desc_entries->desc[i] = desc;
+        }
+        if (vhdx_log_desc_is_valid(&desc, &hdr) == false) {
             ret = -EINVAL;
             goto free_and_exit;
         }
     }
+    if (convert_endian) {
+        desc_entries->hdr = hdr;
+    }
 
     *buffer = desc_entries;
     goto exit;
@@ -403,7 +413,7 @@ static int vhdx_log_flush_desc(BlockDriverState *bs, VHDXLogDescriptor *desc,
 
     buffer = qemu_blockalign(bs, VHDX_LOG_SECTOR_SIZE);
 
-    if (!memcmp(&desc->signature, "desc", 4)) {
+    if (desc->signature == VHDX_LOG_DESC_SIGNATURE) {
         /* data sector */
         if (data == NULL) {
             ret = -EFAULT;
@@ -431,7 +441,7 @@ static int vhdx_log_flush_desc(BlockDriverState *bs, VHDXLogDescriptor *desc,
 
         memcpy(buffer+offset, &desc->trailing_bytes, 4);
 
-    } else if (!memcmp(&desc->signature, "zero", 4)) {
+    } else if (desc->signature == VHDX_LOG_ZERO_SIGNATURE) {
         /* write 'count' sectors of sector */
         memset(buffer, 0, VHDX_LOG_SECTOR_SIZE);
         count = desc->zero_length / VHDX_LOG_SECTOR_SIZE;
@@ -498,13 +508,13 @@ static int vhdx_log_flush(BlockDriverState *bs, BDRVVHDXState *s,
             goto exit;
         }
 
-        ret = vhdx_log_read_desc(bs, s, &logs->log, &desc_entries);
+        ret = vhdx_log_read_desc(bs, s, &logs->log, &desc_entries, true);
         if (ret < 0) {
             goto exit;
         }
 
         for (i = 0; i < desc_entries->hdr.descriptor_count; i++) {
-            if (!memcmp(&desc_entries->desc[i].signature, "desc", 4)) {
+            if (desc_entries->desc[i].signature == VHDX_LOG_DESC_SIGNATURE) {
                 /* data sector, so read a sector to flush */
                 ret = vhdx_log_read_sectors(bs, &logs->log, &sectors_read,
                                             data, 1, false);
@@ -515,6 +525,7 @@ static int vhdx_log_flush(BlockDriverState *bs, BDRVVHDXState *s,
                     ret = -EINVAL;
                     goto exit;
                 }
+                vhdx_log_data_le_import(data);
             }
 
             ret = vhdx_log_flush_desc(bs, &desc_entries->desc[i], data);
@@ -563,9 +574,6 @@ static int vhdx_validate_log_entry(BlockDriverState *bs, BDRVVHDXState *s,
         goto inc_and_exit;
     }
 
-    vhdx_log_entry_hdr_le_import(&hdr);
-
-
     if (vhdx_log_hdr_is_valid(log, &hdr, s) == false) {
         goto inc_and_exit;
     }
@@ -578,13 +586,13 @@ static int vhdx_validate_log_entry(BlockDriverState *bs, BDRVVHDXState *s,
 
     desc_sectors = vhdx_compute_desc_sectors(hdr.descriptor_count);
 
-    /* Read desc sectors, and calculate log checksum */
+    /* Read all log sectors, and calculate log checksum */
 
     total_sectors = hdr.entry_length / VHDX_LOG_SECTOR_SIZE;
 
 
     /* read_desc() will increment the read idx */
-    ret = vhdx_log_read_desc(bs, s, log, &desc_buffer);
+    ret = vhdx_log_read_desc(bs, s, log, &desc_buffer, false);
     if (ret < 0) {
         goto free_and_exit;
     }
@@ -607,7 +615,7 @@ static int vhdx_validate_log_entry(BlockDriverState *bs, BDRVVHDXState *s,
         }
     }
     crc ^= 0xffffffff;
-    if (crc != desc_buffer->hdr.checksum) {
+    if (crc != hdr.checksum) {
         goto free_and_exit;
     }
 
@@ -967,7 +975,6 @@ static int vhdx_log_write(BlockDriverState *bs, BDRVVHDXState *s,
      * last data sector */
     vhdx_update_checksum(buffer, total_length,
                          offsetof(VHDXLogEntryHeader, checksum));
-    cpu_to_le32s((uint32_t *)(buffer + 4));
 
     /* now write to the log */
     ret = vhdx_log_write_sectors(bs, &s->log, &sectors_written, buffer,
diff --git a/block/vhdx.c b/block/vhdx.c
index fedcf9f9ca..febce21f82 100644
--- a/block/vhdx.c
+++ b/block/vhdx.c
@@ -135,10 +135,8 @@ typedef struct VHDXSectorInfo {
  * buf: buffer pointer
  * size: size of buffer (must be > crc_offset+4)
  *
- * Note: The resulting checksum is in the CPU endianness, not necessarily
- *       in the file format endianness (LE).  Any header export to disk should
- *       make sure that vhdx_header_le_export() is used to convert to the
- *       correct endianness
+ * Note: The buffer should have all multi-byte data in little-endian format,
+ *       and the resulting checksum is in little endian format.
  */
 uint32_t vhdx_update_checksum(uint8_t *buf, size_t size, int crc_offset)
 {
@@ -149,6 +147,7 @@ uint32_t vhdx_update_checksum(uint8_t *buf, size_t size, int crc_offset)
 
     memset(buf + crc_offset, 0, sizeof(crc));
     crc =  crc32c(0xffffffff, buf, size);
+    cpu_to_le32s(&crc);
     memcpy(buf + crc_offset, &crc, sizeof(crc));
 
     return crc;
@@ -300,7 +299,7 @@ static int vhdx_write_header(BlockDriverState *bs_file, VHDXHeader *hdr,
 {
     uint8_t *buffer = NULL;
     int ret;
-    VHDXHeader header_le;
+    VHDXHeader *header_le;
 
     assert(bs_file != NULL);
     assert(hdr != NULL);
@@ -321,11 +320,12 @@ static int vhdx_write_header(BlockDriverState *bs_file, VHDXHeader *hdr,
     }
 
     /* overwrite the actual VHDXHeader portion */
-    memcpy(buffer, hdr, sizeof(VHDXHeader));
-    hdr->checksum = vhdx_update_checksum(buffer, VHDX_HEADER_SIZE,
-                                         offsetof(VHDXHeader, checksum));
-    vhdx_header_le_export(hdr, &header_le);
-    ret = bdrv_pwrite_sync(bs_file, offset, &header_le, sizeof(VHDXHeader));
+    header_le = (VHDXHeader *)buffer;
+    memcpy(header_le, hdr, sizeof(VHDXHeader));
+    vhdx_header_le_export(hdr, header_le);
+    vhdx_update_checksum(buffer, VHDX_HEADER_SIZE,
+                         offsetof(VHDXHeader, checksum));
+    ret = bdrv_pwrite_sync(bs_file, offset, header_le, sizeof(VHDXHeader));
 
 exit:
     qemu_vfree(buffer);
@@ -432,13 +432,14 @@ static void vhdx_parse_header(BlockDriverState *bs, BDRVVHDXState *s,
     }
     /* copy over just the relevant portion that we need */
     memcpy(header1, buffer, sizeof(VHDXHeader));
-    vhdx_header_le_import(header1);
 
-    if (vhdx_checksum_is_valid(buffer, VHDX_HEADER_SIZE, 4) &&
-        !memcmp(&header1->signature, "head", 4)             &&
-        header1->version == 1) {
-        h1_seq = header1->sequence_number;
-        h1_valid = true;
+    if (vhdx_checksum_is_valid(buffer, VHDX_HEADER_SIZE, 4)) {
+        vhdx_header_le_import(header1);
+        if (header1->signature == VHDX_HEADER_SIGNATURE &&
+            header1->version == 1) {
+            h1_seq = header1->sequence_number;
+            h1_valid = true;
+        }
     }
 
     ret = bdrv_pread(bs->file, VHDX_HEADER2_OFFSET, buffer, VHDX_HEADER_SIZE);
@@ -447,13 +448,14 @@ static void vhdx_parse_header(BlockDriverState *bs, BDRVVHDXState *s,
     }
     /* copy over just the relevant portion that we need */
     memcpy(header2, buffer, sizeof(VHDXHeader));
-    vhdx_header_le_import(header2);
 
-    if (vhdx_checksum_is_valid(buffer, VHDX_HEADER_SIZE, 4) &&
-        !memcmp(&header2->signature, "head", 4)             &&
-        header2->version == 1) {
-        h2_seq = header2->sequence_number;
-        h2_valid = true;
+    if (vhdx_checksum_is_valid(buffer, VHDX_HEADER_SIZE, 4)) {
+        vhdx_header_le_import(header2);
+        if (header2->signature == VHDX_HEADER_SIGNATURE &&
+            header2->version == 1) {
+            h2_seq = header2->sequence_number;
+            h2_valid = true;
+        }
     }
 
     /* If there is only 1 valid header (or no valid headers), we
@@ -519,15 +521,21 @@ static int vhdx_open_region_tables(BlockDriverState *bs, BDRVVHDXState *s)
         goto fail;
     }
     memcpy(&s->rt, buffer, sizeof(s->rt));
-    vhdx_region_header_le_import(&s->rt);
     offset += sizeof(s->rt);
 
-    if (!vhdx_checksum_is_valid(buffer, VHDX_HEADER_BLOCK_SIZE, 4) ||
-        memcmp(&s->rt.signature, "regi", 4)) {
+    if (!vhdx_checksum_is_valid(buffer, VHDX_HEADER_BLOCK_SIZE, 4)) {
+        ret = -EINVAL;
+        goto fail;
+    }
+
+    vhdx_region_header_le_import(&s->rt);
+
+    if (s->rt.signature != VHDX_REGION_SIGNATURE) {
         ret = -EINVAL;
         goto fail;
     }
 
+
     /* Per spec, maximum region table entry count is 2047 */
     if (s->rt.entry_count > 2047) {
         ret = -EINVAL;
@@ -630,7 +638,7 @@ static int vhdx_parse_metadata(BlockDriverState *bs, BDRVVHDXState *s)
 
     vhdx_metadata_header_le_import(&s->metadata_hdr);
 
-    if (memcmp(&s->metadata_hdr.signature, "metadata", 8)) {
+    if (s->metadata_hdr.signature != VHDX_METADATA_SIGNATURE) {
         ret = -EINVAL;
         goto exit;
     }
@@ -951,7 +959,6 @@ static int vhdx_open(BlockDriverState *bs, QDict *options, int flags,
 
     /* s->bat is freed in vhdx_close() */
     s->bat = qemu_blockalign(bs, s->bat_rt.length);
-
     ret = bdrv_pread(bs->file, s->bat_offset, s->bat, s->bat_rt.length);
     if (ret < 0) {
         goto fail;
@@ -1540,7 +1547,8 @@ exit:
  */
 static int vhdx_create_bat(BlockDriverState *bs, BDRVVHDXState *s,
                            uint64_t image_size, VHDXImageType type,
-                           bool use_zero_blocks, VHDXRegionTableEntry *rt_bat)
+                           bool use_zero_blocks, uint64_t file_offset,
+                           uint32_t length)
 {
     int ret = 0;
     uint64_t data_file_offset;
@@ -1555,7 +1563,7 @@ static int vhdx_create_bat(BlockDriverState *bs, BDRVVHDXState *s,
     /* this gives a data start after BAT/bitmap entries, and well
      * past any metadata entries (with a 4 MB buffer for future
      * expansion */
-    data_file_offset = rt_bat->file_offset + rt_bat->length + 5 * MiB;
+    data_file_offset = file_offset + length + 5 * MiB;
     total_sectors = image_size >> s->logical_sector_size_bits;
 
     if (type == VHDX_TYPE_DYNAMIC) {
@@ -1579,7 +1587,7 @@ static int vhdx_create_bat(BlockDriverState *bs, BDRVVHDXState *s,
                 use_zero_blocks ||
                 bdrv_has_zero_init(bs) == 0) {
         /* for a fixed file, the default BAT entry is not zero */
-        s->bat = g_malloc0(rt_bat->length);
+        s->bat = g_malloc0(length);
         block_state = type == VHDX_TYPE_FIXED ? PAYLOAD_BLOCK_FULLY_PRESENT :
                                                 PAYLOAD_BLOCK_NOT_PRESENT;
         block_state = use_zero_blocks ? PAYLOAD_BLOCK_ZERO : block_state;
@@ -1594,7 +1602,7 @@ static int vhdx_create_bat(BlockDriverState *bs, BDRVVHDXState *s,
             cpu_to_le64s(&s->bat[sinfo.bat_idx]);
             sector_num += s->sectors_per_block;
         }
-        ret = bdrv_pwrite(bs, rt_bat->file_offset, s->bat, rt_bat->length);
+        ret = bdrv_pwrite(bs, file_offset, s->bat, length);
         if (ret < 0) {
             goto exit;
         }
@@ -1626,6 +1634,8 @@ static int vhdx_create_new_region_table(BlockDriverState *bs,
     int ret = 0;
     uint32_t offset = 0;
     void *buffer = NULL;
+    uint64_t bat_file_offset;
+    uint32_t bat_length;
     BDRVVHDXState *s = NULL;
     VHDXRegionTableHeader *region_table;
     VHDXRegionTableEntry *rt_bat;
@@ -1674,19 +1684,26 @@ static int vhdx_create_new_region_table(BlockDriverState *bs,
     rt_metadata->length      = 1 * MiB; /* min size, and more than enough */
     *metadata_offset = rt_metadata->file_offset;
 
+    bat_file_offset = rt_bat->file_offset;
+    bat_length = rt_bat->length;
+
+    vhdx_region_header_le_export(region_table);
+    vhdx_region_entry_le_export(rt_bat);
+    vhdx_region_entry_le_export(rt_metadata);
+
     vhdx_update_checksum(buffer, VHDX_HEADER_BLOCK_SIZE,
                          offsetof(VHDXRegionTableHeader, checksum));
 
 
     /* The region table gives us the data we need to create the BAT,
      * so do that now */
-    ret = vhdx_create_bat(bs, s, image_size, type, use_zero_blocks, rt_bat);
+    ret = vhdx_create_bat(bs, s, image_size, type, use_zero_blocks,
+                          bat_file_offset, bat_length);
+    if (ret < 0) {
+        goto exit;
+    }
 
     /* Now write out the region headers to disk */
-    vhdx_region_header_le_export(region_table);
-    vhdx_region_entry_le_export(rt_bat);
-    vhdx_region_entry_le_export(rt_metadata);
-
     ret = bdrv_pwrite(bs, VHDX_REGION_TABLE_OFFSET, buffer,
                       VHDX_HEADER_BLOCK_SIZE);
     if (ret < 0) {
diff --git a/block/vhdx.h b/block/vhdx.h
index 5370010c59..b4a12a081e 100644
--- a/block/vhdx.h
+++ b/block/vhdx.h
@@ -435,6 +435,7 @@ void vhdx_header_le_import(VHDXHeader *h);
 void vhdx_header_le_export(VHDXHeader *orig_h, VHDXHeader *new_h);
 void vhdx_log_desc_le_import(VHDXLogDescriptor *d);
 void vhdx_log_desc_le_export(VHDXLogDescriptor *d);
+void vhdx_log_data_le_import(VHDXLogDataSector *d);
 void vhdx_log_data_le_export(VHDXLogDataSector *d);
 void vhdx_log_entry_hdr_le_import(VHDXLogEntryHeader *hdr);
 void vhdx_log_entry_hdr_le_export(VHDXLogEntryHeader *hdr);