native/interop: use oracle request signers for oracle response witness

Oracle responses must use the same set of signers as oracle requests even
though the transaction itself is signed by oracle nodes/contract.

We can probably improve interop.Context by removing Tx field completely and
adding more functionality to Container, but it's not very convenient for
VerifyWitness and will require adding more stub-like methods for Block, so Tx
is used for now (and we do have it in every relevant case).

pkg/core/helper_test.go

@@ -540,7 +540,7 @@ func addSigners(sender util.Uint160, txs ...*transaction.Transaction) {
 	for _, tx := range txs {
 		tx.Signers = []transaction.Signer{{
 			Account:          sender,
-			Scopes:           transaction.CalledByEntry,
+			Scopes:           transaction.Global,
 			AllowedContracts: nil,
 			AllowedGroups:    nil,
 		}}

pkg/core/interop/context.go

@@ -51,6 +51,7 @@ type Context struct {
 	cancelFuncs   []context.CancelFunc
 	getContract   func(dao.DAO, util.Uint160) (*state.Contract, error)
 	baseExecFee   int64
+	signers       []transaction.Signer
 }
 
 // NewContext returns new interop context.
@@ -89,6 +90,22 @@ func (ic *Context) InitNonceData() {
 	}
 }
 
+// UseSigners allows overriding signers used in this context.
+func (ic *Context) UseSigners(s []transaction.Signer) {
+	ic.signers = s
+}
+
+// Signers returns signers witnessing current execution context.
+func (ic *Context) Signers() []transaction.Signer {
+	if ic.signers != nil {
+		return ic.signers
+	}
+	if ic.Tx != nil {
+		return ic.Tx.Signers
+	}
+	return nil
+}
+
 // Function binds function name, id with the function itself and price,
 // it's supposed to be inited once for all interopContexts, so it doesn't use
 // vm.InteropFuncPrice directly.

pkg/core/interop/runtime/witness.go

@@ -22,11 +22,7 @@ func CheckHashedWitness(ic *interop.Context, hash util.Uint160) (bool, error) {
 	if !callingSH.Equals(util.Uint160{}) && hash.Equals(callingSH) {
 		return true, nil
 	}
-	if tx, ok := ic.Container.(*transaction.Transaction); ok {
+	return checkScope(ic, hash)
-		return checkScope(ic, tx, ic.VM, hash)
-	}
-
-	return false, errors.New("script container is not a transaction")
 }
 
 type scopeContext struct {
@@ -61,21 +57,26 @@ func (sc scopeContext) CurrentScriptHasGroup(k *keys.PublicKey) (bool, error) {
 	return sc.checkScriptGroups(sc.GetCurrentScriptHash(), k)
 }
 
-func checkScope(ic *interop.Context, tx *transaction.Transaction, v *vm.VM, hash util.Uint160) (bool, error) {
+func checkScope(ic *interop.Context, hash util.Uint160) (bool, error) {
-	for _, c := range tx.Signers {
+	signers := ic.Signers()
+	if len(signers) == 0 {
+		return false, errors.New("no valid signers")
+	}
+	for i := range signers {
+		c := &signers[i]
 		if c.Account == hash {
 			if c.Scopes == transaction.Global {
 				return true, nil
 			}
 			if c.Scopes&transaction.CalledByEntry != 0 {
-				callingScriptHash := v.GetCallingScriptHash()
+				callingScriptHash := ic.VM.GetCallingScriptHash()
-				entryScriptHash := v.GetEntryScriptHash()
+				entryScriptHash := ic.VM.GetEntryScriptHash()
 				if callingScriptHash.Equals(util.Uint160{}) || callingScriptHash == entryScriptHash {
 					return true, nil
 				}
 			}
 			if c.Scopes&transaction.CustomContracts != 0 {
-				currentScriptHash := v.GetCurrentScriptHash()
+				currentScriptHash := ic.VM.GetCurrentScriptHash()
 				for _, allowedContract := range c.AllowedContracts {
 					if allowedContract == currentScriptHash {
 						return true, nil
@@ -83,7 +84,7 @@ func checkScope(ic *interop.Context, tx *transaction.Transaction, v *vm.VM, hash
 				}
 			}
 			if c.Scopes&transaction.CustomGroups != 0 {
-				groups, err := getContractGroups(v, ic, v.GetCurrentScriptHash())
+				groups, err := getContractGroups(ic.VM, ic, ic.VM.GetCurrentScriptHash())
 				if err != nil {
 					return false, err
 				}
@@ -95,7 +96,7 @@ func checkScope(ic *interop.Context, tx *transaction.Transaction, v *vm.VM, hash
 				}
 			}
 			if c.Scopes&transaction.Rules != 0 {
-				ctx := scopeContext{v, ic}
+				ctx := scopeContext{ic.VM, ic}
 				for _, r := range c.Rules {
 					res, err := r.Condition.Match(ctx)
 					if err != nil {

pkg/core/interop_system_test.go

@@ -1183,7 +1183,7 @@ func TestRuntimeCheckWitness(t *testing.T) {
 						},
 					},
 				}
-				ic.Container = tx
+				ic.Tx = tx
 				callingScriptHash := scriptHash
 				loadScriptWithHashAndFlags(ic, script, callingScriptHash, callflag.All)
 				ic.VM.LoadScriptWithHash([]byte{0x1}, random.Uint160(), callflag.AllowCall)
@@ -1205,7 +1205,7 @@ func TestRuntimeCheckWitness(t *testing.T) {
 						},
 					},
 				}
-				ic.Container = tx
+				ic.Tx = tx
 				callingScriptHash := scriptHash
 				loadScriptWithHashAndFlags(ic, script, callingScriptHash, callflag.All)
 				ic.VM.LoadScriptWithHash([]byte{0x1}, random.Uint160(), callflag.AllowCall)
@@ -1242,7 +1242,7 @@ func TestRuntimeCheckWitness(t *testing.T) {
 					},
 				}
 				loadScriptWithHashAndFlags(ic, script, scriptHash, callflag.ReadStates)
-				ic.Container = tx
+				ic.Tx = tx
 				check(t, ic, hash.BytesBE(), false, true)
 			})
 			t.Run("CalledByEntry", func(t *testing.T) {
@@ -1256,7 +1256,7 @@ func TestRuntimeCheckWitness(t *testing.T) {
 					},
 				}
 				loadScriptWithHashAndFlags(ic, script, scriptHash, callflag.ReadStates)
-				ic.Container = tx
+				ic.Tx = tx
 				check(t, ic, hash.BytesBE(), false, true)
 			})
 			t.Run("CustomContracts", func(t *testing.T) {
@@ -1271,7 +1271,7 @@ func TestRuntimeCheckWitness(t *testing.T) {
 					},
 				}
 				loadScriptWithHashAndFlags(ic, script, scriptHash, callflag.ReadStates)
-				ic.Container = tx
+				ic.Tx = tx
 				check(t, ic, hash.BytesBE(), false, true)
 			})
 			t.Run("CustomGroups", func(t *testing.T) {
@@ -1287,7 +1287,7 @@ func TestRuntimeCheckWitness(t *testing.T) {
 						},
 					}
 					loadScriptWithHashAndFlags(ic, script, scriptHash, callflag.ReadStates)
-					ic.Container = tx
+					ic.Tx = tx
 					check(t, ic, hash.BytesBE(), false, false)
 				})
 				t.Run("positive", func(t *testing.T) {
@@ -1319,7 +1319,7 @@ func TestRuntimeCheckWitness(t *testing.T) {
 					}
 					require.NoError(t, bc.contracts.Management.PutContractState(ic.DAO, contractState))
 					loadScriptWithHashAndFlags(ic, contractScript, contractScriptHash, callflag.All)
-					ic.Container = tx
+					ic.Tx = tx
 					check(t, ic, targetHash.BytesBE(), false, true)
 				})
 			})
@@ -1339,7 +1339,7 @@ func TestRuntimeCheckWitness(t *testing.T) {
 						},
 					}
 					loadScriptWithHashAndFlags(ic, script, scriptHash, callflag.ReadStates)
-					ic.Container = tx
+					ic.Tx = tx
 					check(t, ic, hash.BytesBE(), false, false)
 				})
 				t.Run("allow", func(t *testing.T) {
@@ -1358,7 +1358,7 @@ func TestRuntimeCheckWitness(t *testing.T) {
 						},
 					}
 					loadScriptWithHashAndFlags(ic, script, scriptHash, callflag.ReadStates)
-					ic.Container = tx
+					ic.Tx = tx
 					check(t, ic, hash.BytesBE(), false, true)
 				})
 				t.Run("deny", func(t *testing.T) {
@@ -1377,7 +1377,7 @@ func TestRuntimeCheckWitness(t *testing.T) {
 						},
 					}
 					loadScriptWithHashAndFlags(ic, script, scriptHash, callflag.ReadStates)
-					ic.Container = tx
+					ic.Tx = tx
 					check(t, ic, hash.BytesBE(), false, false)
 				})
 			})
@@ -1392,7 +1392,7 @@ func TestRuntimeCheckWitness(t *testing.T) {
 					},
 				}
 				loadScriptWithHashAndFlags(ic, script, scriptHash, callflag.ReadStates)
-				ic.Container = tx
+				ic.Tx = tx
 				check(t, ic, hash.BytesBE(), false, false)
 			})
 		})

pkg/core/native/oracle.go

@@ -275,6 +275,12 @@ func (o *Oracle) FinishInternal(ic *interop.Context) error {
 			stackitem.Make(req.OriginalTxID.BytesBE()),
 		}),
 	})
+	origTx, _, err := ic.DAO.GetTransaction(req.OriginalTxID)
+	if err != nil {
+		return ErrRequestNotFound
+	}
+	ic.UseSigners(origTx.Signers)
+	defer ic.UseSigners(nil)
 
 	userData, err := stackitem.Deserialize(req.UserData)
 	if err != nil {

pkg/core/native_oracle_test.go

@@ -43,6 +43,11 @@ func getOracleContractState(h util.Uint160, stdHash util.Uint160) *state.Contrac
 
 	// `handle` method aborts if len(userData) == 2
 	offset := w.Len()
+	emit.Bytes(w.BinWriter, neoOwner.BytesBE())
+	emit.Syscall(w.BinWriter, interopnames.SystemRuntimeCheckWitness)
+	emit.Instruction(w.BinWriter, opcode.JMPIF, []byte{3})
+	emit.Opcodes(w.BinWriter, opcode.ABORT)
+
 	emit.Opcodes(w.BinWriter, opcode.OVER)
 	emit.Opcodes(w.BinWriter, opcode.SIZE)
 	emit.Int(w.BinWriter, 2)