check block signatures during sync

chain/gen/mining.go

@@ -137,9 +137,9 @@ func MinerCreateBlock(ctx context.Context, sm *stmgr.StateManager, w *wallet.Wal
 
 	// TODO: set timestamp
 
-	nosigbytes, err := next.Serialize()
+	nosigbytes, err := next.SigningBytes()
 	if err != nil {
-		return nil, xerrors.Errorf("failed to serialize block header with no signature: %w", err)
+		return nil, xerrors.Errorf("failed to get signing bytes for block: %w", err)
 	}
 
 	waddr, err := vm.ResolveToKeyAddr(vmi.StateTree(), cst, worker)

chain/sync.go

@@ -373,6 +373,15 @@ func (syncer *Syncer) validateTickets(ctx context.Context, mworker address.Addre
 	return nil
 }
 
+func checkBlockSignature(blk *types.BlockHeader, worker address.Address) error {
+	sigb, err := blk.SigningBytes()
+	if err != nil {
+		return xerrors.Errorf("failed to get block signing bytes: %w", err)
+	}
+
+	return blk.BlockSig.Verify(worker, sigb)
+}
+
 // Should match up with 'Semantical Validation' in validation.md in the spec
 func (syncer *Syncer) ValidateBlock(ctx context.Context, b *types.FullBlock) error {
 	h := b.Header
@@ -404,6 +413,10 @@ func (syncer *Syncer) ValidateBlock(ctx context.Context, b *types.FullBlock) err
 		return xerrors.Errorf("GetMinerWorker failed: %w", err)
 	}
 
+	if err := checkBlockSignature(h, waddr); err != nil {
+		return xerrors.Errorf("check block signature failed: %w", err)
+	}
+
 	if err := syncer.validateTickets(ctx, waddr, h.Tickets, baseTs); err != nil {
 		return xerrors.Errorf("validating block tickets failed: %w", err)
 	}

chain/types/blockheader.go

@@ -93,6 +93,13 @@ func (blk *BlockHeader) LastTicket() *Ticket {
 	return blk.Tickets[len(blk.Tickets)-1]
 }
 
+func (blk *BlockHeader) SigningBytes() ([]byte, error) {
+	blkcopy := *blk
+	blkcopy.BlockSig = Signature{}
+
+	return blkcopy.Serialize()
+}
+
 type MsgMeta struct {
 	BlsMessages   cid.Cid
 	SecpkMessages cid.Cid