diff mbox series

[12/14] nbd/client: Accept 64-bit block status chunks

Message ID 20211203231539.3900865-13-eblake@redhat.com
State New
Headers show
Series qemu patches for NBD_OPT_EXTENDED_HEADERS | expand

Commit Message

Eric Blake Dec. 3, 2021, 11:15 p.m. UTC
Because we use NBD_CMD_FLAG_REQ_ONE with NBD_CMD_BLOCK_STATUS, a
client in narrow mode should not be able to provoke a server into
sending a block status result larger than the client's 32-bit request.
But in extended mode, a 64-bit status request must be able to handle a
64-bit status result, once a future patch enables the client
requesting extended mode.  We can also tolerate a non-compliant server
sending the new chunk even when it should not.

Signed-off-by: Eric Blake <eblake@redhat.com>
---
 block/nbd.c | 38 +++++++++++++++++++++++++++-----------
 1 file changed, 27 insertions(+), 11 deletions(-)
diff mbox series

Patch

diff --git a/block/nbd.c b/block/nbd.c
index c5dea864ebb6..bd4a9c407bde 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -563,13 +563,15 @@  static int nbd_parse_offset_hole_payload(BDRVNBDState *s,
  */
 static int nbd_parse_blockstatus_payload(BDRVNBDState *s,
                                          NBDStructuredReplyChunk *chunk,
-                                         uint8_t *payload, uint64_t orig_length,
-                                         NBDExtent *extent, Error **errp)
+                                         uint8_t *payload, bool wide,
+                                         uint64_t orig_length,
+                                         NBDExtentExt *extent, Error **errp)
 {
     uint32_t context_id;
+    size_t len = wide ? sizeof(*extent) : sizeof(NBDExtent);

     /* The server succeeded, so it must have sent [at least] one extent */
-    if (chunk->length < sizeof(context_id) + sizeof(*extent)) {
+    if (chunk->length < sizeof(context_id) + len) {
         error_setg(errp, "Protocol error: invalid payload for "
                          "NBD_REPLY_TYPE_BLOCK_STATUS");
         return -EINVAL;
@@ -584,8 +586,16 @@  static int nbd_parse_blockstatus_payload(BDRVNBDState *s,
         return -EINVAL;
     }

-    extent->length = payload_advance32(&payload);
-    extent->flags = payload_advance32(&payload);
+    if (wide) {
+        extent->length = payload_advance64(&payload);
+        extent->flags = payload_advance32(&payload);
+        if (payload_advance32(&payload) != 0) {
+            trace_nbd_parse_blockstatus_compliance("non-zero extent padding");
+        }
+    } else {
+        extent->length = payload_advance32(&payload);
+        extent->flags = payload_advance32(&payload);
+    }

     if (extent->length == 0) {
         error_setg(errp, "Protocol error: server sent status chunk with "
@@ -625,7 +635,7 @@  static int nbd_parse_blockstatus_payload(BDRVNBDState *s,
      * connection; just ignore trailing extents, and clamp things to
      * the length of our request.
      */
-    if (chunk->length > sizeof(context_id) + sizeof(*extent)) {
+    if (chunk->length > sizeof(context_id) + len) {
         trace_nbd_parse_blockstatus_compliance("more than one extent");
     }
     if (extent->length > orig_length) {
@@ -1081,7 +1091,7 @@  static int nbd_co_receive_cmdread_reply(BDRVNBDState *s, uint64_t handle,

 static int nbd_co_receive_blockstatus_reply(BDRVNBDState *s,
                                             uint64_t handle, uint64_t length,
-                                            NBDExtent *extent,
+                                            NBDExtentExt *extent,
                                             int *request_ret, Error **errp)
 {
     NBDReplyChunkIter iter;
@@ -1098,6 +1108,11 @@  static int nbd_co_receive_blockstatus_reply(BDRVNBDState *s,
         assert(nbd_reply_is_structured(&reply));

         switch (chunk->type) {
+        case NBD_REPLY_TYPE_BLOCK_STATUS_EXT:
+            if (!s->info.extended_headers) {
+                trace_nbd_extended_headers_compliance("block_status_ext");
+            }
+            /* fallthrough */
         case NBD_REPLY_TYPE_BLOCK_STATUS:
             if (received) {
                 nbd_channel_error(s, -EINVAL);
@@ -1106,9 +1121,10 @@  static int nbd_co_receive_blockstatus_reply(BDRVNBDState *s,
             }
             received = true;

-            ret = nbd_parse_blockstatus_payload(s, &reply.structured,
-                                                payload, length, extent,
-                                                &local_err);
+            ret = nbd_parse_blockstatus_payload(
+                s, &reply.structured, payload,
+                chunk->type == NBD_REPLY_TYPE_BLOCK_STATUS_EXT,
+                length, extent, &local_err);
             if (ret < 0) {
                 nbd_channel_error(s, ret);
                 nbd_iter_channel_error(&iter, ret, &local_err);
@@ -1337,7 +1353,7 @@  static int coroutine_fn nbd_client_co_block_status(
         int64_t *pnum, int64_t *map, BlockDriverState **file)
 {
     int ret, request_ret;
-    NBDExtent extent = { 0 };
+    NBDExtentExt extent = { 0 };
     BDRVNBDState *s = (BDRVNBDState *)bs->opaque;
     Error *local_err = NULL;