BFT Block Puller: verifier

Signed-off-by: Yoav Tock <[email protected]>
Change-Id: I71aa3fd6f0ea0e4ea529614830ea95dfedb3cd36

common/deliver/deliver.go

@@ -4,6 +4,8 @@ Copyright IBM Corp. All Rights Reserved.
 SPDX-License-Identifier: Apache-2.0
 */
 
+// Package deliver contains an implementation of the server-side handlers of the gRPC delivery service.
+// The delivery service runs in the orderer and is used to deliver blocks to peers, as well as to other orderers.
 package deliver
 
 import (

common/deliverclient/block_verification.go

@@ -0,0 +1,350 @@
+/*
+Copyright IBM Corp. All Rights Reserved.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package deliverclient
+
+import (
+	"bytes"
+
+	"github.com/hyperledger/fabric-protos-go/common"
+	"github.com/hyperledger/fabric/bccsp"
+	"github.com/hyperledger/fabric/common/configtx"
+	"github.com/hyperledger/fabric/common/flogging"
+	"github.com/hyperledger/fabric/protoutil"
+	"github.com/pkg/errors"
+)
+
+type CloneableUpdatableBlockVerifier interface {
+	// VerifyBlock checks block integrity and its relation to the chain, and verifies the signatures.
+	VerifyBlock(block *common.Block) error
+
+	// VerifyBlockAttestation does the same as VerifyBlock, except it assumes block.Data = nil. It therefore does not
+	// compute the block.Data.Hash() and compare it to the block.Header.DataHash. This is used when the orderer
+	// delivers a block with header & metadata only, as an attestation of block existence.
+	VerifyBlockAttestation(block *common.Block) error
+
+	// UpdateConfig sets the config by which blocks are verified. It is assumed that this config block had already been
+	// verified using the VerifyBlock method immediately prior to calling this method.
+	UpdateConfig(configBlock *common.Block) error
+
+	// UpdateBlockHeader saves the last block header that was verified and handled successfully.
+	// This must be called after VerifyBlock and VerifyBlockAttestation and successfully handling the block.
+	UpdateBlockHeader(block *common.Block)
+
+	// Clone makes a copy from the current verifier, a copy that can keep being updated independently.
+	Clone() CloneableUpdatableBlockVerifier
+}
+
+// BlockVerificationAssistant verifies the integrity and signatures of a block stream, while keeping a copy of the
+// latest configuration.
+//
+// Every time a config block arrives, it must first be verified using VerifyBlock and then
+// used as an argument to the UpdateConfig method.
+// The block stream could be composed of either:
+// - full blocks, which are verified using the VerifyBlock method, or
+// - block attestations (a header+metadata, with nil data) which are verified using the VerifyBlockAttestation method.
+// In both cases, config blocks must arrive in full.
+type BlockVerificationAssistant struct {
+	channelID string
+
+	// Creates the sigVerifierFunc whenever the configuration is set or updated.
+	verifierAssembler *BlockVerifierAssembler
+	// Verifies block signature(s). Recreated whenever the configuration is set or updated.
+	sigVerifierFunc protoutil.BlockVerifierFunc
+	// The current config block header.
+	// It may be nil if the BlockVerificationAssistant is created from common.Config and not a config block.
+	// After 'UpdateConfig(*common.Block) error' this field is always set.
+	configBlockHeader *common.BlockHeader
+	// The last block header may include the number only, in case we start from common.Config.
+	lastBlockHeader *common.BlockHeader
+	// The last block header hash is given when we start from common.Config, and is computed otherwise.
+	lastBlockHeaderHash []byte
+
+	logger *flogging.FabricLogger
+}
+
+// NewBlockVerificationAssistant creates a new BlockVerificationAssistant from a config block.
+// This is used in the orderer, where we always have access to the last config block.
+func NewBlockVerificationAssistant(configBlock *common.Block, lastBlock *common.Block, cryptoProvider bccsp.BCCSP, lg *flogging.FabricLogger) (*BlockVerificationAssistant, error) {
+	if configBlock == nil {
+		return nil, errors.Errorf("config block is nil")
+	}
+	if configBlock.Header == nil {
+		return nil, errors.Errorf("config block header is nil")
+	}
+	configIndex, err := protoutil.GetLastConfigIndexFromBlock(configBlock)
+	if err != nil {
+		return nil, errors.WithMessage(err, "error getting config index from config block")
+	}
+	if configIndex != configBlock.Header.Number {
+		return nil, errors.Errorf("config block number [%d] is different than its own config index [%d]", configBlock.Header.Number, configIndex)
+	}
+
+	if lastBlock != nil {
+		if lastBlock.Header == nil {
+			return nil, errors.Errorf("last verified block header is nil")
+		}
+		lastBlockConfigIndex, err := protoutil.GetLastConfigIndexFromBlock(lastBlock)
+		if err != nil {
+			return nil, errors.WithMessage(err, "error getting config index from last verified block")
+		}
+		if lastBlockConfigIndex != configBlock.Header.Number {
+			return nil, errors.Errorf("last verified block config index [%d] is different than the config block number [%d]", lastBlockConfigIndex, configBlock.Header.Number)
+		}
+	} else {
+		lastBlock = configBlock
+	}
+
+	configTx, err := protoutil.ExtractEnvelope(configBlock, 0)
+	if err != nil {
+		return nil, errors.WithMessage(err, "error extracting envelope")
+	}
+	payload, err := protoutil.UnmarshalPayload(configTx.Payload)
+	if err != nil {
+		return nil, errors.WithMessage(err, "error umarshaling envelope to payload")
+	}
+
+	if payload.Header == nil {
+		return nil, errors.New("missing channel header")
+	}
+
+	chdr, err := protoutil.UnmarshalChannelHeader(payload.Header.ChannelHeader)
+	if err != nil {
+		return nil, errors.WithMessage(err, "error unmarshalling channel header")
+	}
+
+	configEnvelope, err := configtx.UnmarshalConfigEnvelope(payload.Data)
+	if err != nil {
+		return nil, errors.WithMessage(err, "error umarshaling config envelope from payload data")
+	}
+
+	bva := &BlockVerifierAssembler{
+		Logger: lg,
+		BCCSP:  cryptoProvider,
+	}
+	verifierFunc, err := bva.VerifierFromConfig(configEnvelope, chdr.GetChannelId())
+	if err != nil {
+		return nil, errors.WithMessage(err, "error creating verifier function")
+	}
+
+	a := &BlockVerificationAssistant{
+		channelID:           chdr.GetChannelId(),
+		verifierAssembler:   bva,
+		sigVerifierFunc:     verifierFunc,
+		configBlockHeader:   configBlock.Header,
+		lastBlockHeader:     lastBlock.Header,
+		lastBlockHeaderHash: protoutil.BlockHeaderHash(lastBlock.Header),
+		logger:              lg,
+	}
+
+	return a, nil
+}
+
+// NewBlockVerificationAssistantFromConfig creates a new BlockVerificationAssistant from a common.Config.
+// This is used in the peer, since when the peer starts from a snapshot we may not have access to the last config-block,
+// only to the config object.
+func NewBlockVerificationAssistantFromConfig(config *common.Config, lastBlockNumber uint64, lastBlockHeaderHash []byte, channelID string, cryptoProvider bccsp.BCCSP, lg *flogging.FabricLogger) (*BlockVerificationAssistant, error) {
+	if config == nil {
+		return nil, errors.Errorf("config is nil")
+	}
+
+	if len(lastBlockHeaderHash) == 0 {
+		return nil, errors.Errorf("last block header hash is missing")
+	}
+
+	bva := &BlockVerifierAssembler{
+		Logger: lg,
+		BCCSP:  cryptoProvider,
+	}
+	verifierFunc, err := bva.VerifierFromConfig(&common.ConfigEnvelope{Config: config}, channelID)
+	if err != nil {
+		return nil, errors.WithMessage(err, "error creating verifier function")
+	}
+
+	a := &BlockVerificationAssistant{
+		channelID:           channelID,
+		verifierAssembler:   bva,
+		sigVerifierFunc:     verifierFunc,
+		lastBlockHeader:     &common.BlockHeader{Number: lastBlockNumber},
+		lastBlockHeaderHash: lastBlockHeaderHash,
+		logger:              lg,
+	}
+
+	return a, nil
+}
+
+func (a *BlockVerificationAssistant) Clone() CloneableUpdatableBlockVerifier {
+	c := &BlockVerificationAssistant{
+		channelID:           a.channelID,
+		verifierAssembler:   a.verifierAssembler,
+		sigVerifierFunc:     a.sigVerifierFunc,
+		configBlockHeader:   a.configBlockHeader,
+		lastBlockHeader:     a.lastBlockHeader,
+		lastBlockHeaderHash: a.lastBlockHeaderHash,
+		logger:              a.logger,
+	}
+	return c
+}
+
+// UpdateConfig sets the config by which blocks are verified. It is assumed that this config block had already been
+// verified using the VerifyBlock method immediately prior to calling this method.
+func (a *BlockVerificationAssistant) UpdateConfig(configBlock *common.Block) error {
+	configTx, err := protoutil.ExtractEnvelope(configBlock, 0)
+	if err != nil {
+		return errors.WithMessage(err, "error extracting envelope")
+	}
+
+	payload, err := protoutil.UnmarshalPayload(configTx.Payload)
+	if err != nil {
+		return errors.WithMessage(err, "error umarshaling envelope to payload")
+	}
+
+	if payload.Header == nil {
+		return errors.New("missing channel header")
+	}
+
+	chdr, err := protoutil.UnmarshalChannelHeader(payload.Header.ChannelHeader)
+	if err != nil {
+		return errors.WithMessage(err, "error unmarshalling channel header")
+	}
+
+	if chdr.GetChannelId() != a.channelID {
+		return errors.New("config block channel ID '%s' does not match expected: '%s'")
+	}
+
+	configEnvelope, err := configtx.UnmarshalConfigEnvelope(payload.Data)
+	if err != nil {
+		return errors.WithMessage(err, "error umarshaling config envelope from payload data")
+	}
+
+	verifierFunc, err := a.verifierAssembler.VerifierFromConfig(configEnvelope, chdr.GetChannelId())
+	if err != nil {
+		return errors.WithMessage(err, "error creating verifier function")
+	}
+
+	a.configBlockHeader = configBlock.Header
+	a.lastBlockHeader = configBlock.Header
+	a.lastBlockHeaderHash = protoutil.BlockHeaderHash(configBlock.Header)
+	a.sigVerifierFunc = verifierFunc
+
+	return nil
+}
+
+// VerifyBlock checks block integrity and its relation to the chain, and verifies the signatures.
+func (a *BlockVerificationAssistant) VerifyBlock(block *common.Block) error {
+	if err := a.verifyHeader(block); err != nil {
+		return err
+	}
+
+	// Verify channel ID
+	channelID, err := protoutil.GetChannelIDFromBlock(block)
+	if err != nil {
+		return errors.Wrapf(err, "failed getting channel id from block number [%d] on channel [%s]", block.Header.Number, a.channelID)
+	}
+
+	if channelID != a.channelID {
+		return errors.Errorf("invalid block's channel id. Expected [%s]. Given [%s]", a.channelID, channelID)
+	}
+
+	if err = a.verifyMetadata(block); err != nil {
+		return err
+	}
+
+	dataHash, err := protoutil.BlockDataHash(block.Data)
+	if err != nil {
+		return errors.Wrapf(err, "failed to verify transactions are well formed for block with id [%d] on channel [%s]", block.Header.Number, a.channelID)
+	}
+
+	// Verify that Header.DataHash is equal to the hash of block.Data
+	// This is to ensure that the header is consistent with the data carried by this block
+	if !bytes.Equal(dataHash, block.Header.DataHash) {
+		return errors.Errorf("Header.DataHash is different from Hash(block.Data) for block with id [%d] on channel [%s]", block.Header.Number, a.channelID)
+	}
+
+	err = a.sigVerifierFunc(block.Header, block.Metadata)
+	if err == nil {
+		a.lastBlockHeader = block.Header
+		a.lastBlockHeaderHash = protoutil.BlockHeaderHash(block.Header)
+	}
+
+	return err
+}
+
+// VerifyBlockAttestation does the same as VerifyBlock, except it assumes block.Data = nil. It therefore does not
+// compute the block.Data.Hash() and compare it to the block.Header.DataHash. This is used when the orderer
+// delivers a block with header & metadata only, as an attestation of block existence.
+func (a *BlockVerificationAssistant) VerifyBlockAttestation(block *common.Block) error {
+	if err := a.verifyHeader(block); err != nil {
+		return err
+	}
+
+	if err := a.verifyMetadata(block); err != nil {
+		return err
+	}
+
+	err := a.sigVerifierFunc(block.Header, block.Metadata)
+	if err == nil {
+		a.lastBlockHeader = block.Header
+		a.lastBlockHeaderHash = protoutil.BlockHeaderHash(block.Header)
+	}
+
+	return err
+}
+
+// UpdateBlockHeader saves the last block header that was verified and handled successfully.
+// This must be called after VerifyBlock and VerifyBlockAttestation and successfully handling the block.
+func (a *BlockVerificationAssistant) UpdateBlockHeader(block *common.Block) {
+	a.lastBlockHeader = block.Header
+	a.lastBlockHeaderHash = protoutil.BlockHeaderHash(block.Header)
+}
+
+func (a *BlockVerificationAssistant) verifyMetadata(block *common.Block) error {
+	if block.Metadata == nil || len(block.Metadata.Metadata) == 0 {
+		return errors.Errorf("block with id [%d] on channel [%s] does not have metadata", block.Header.Number, a.channelID)
+	}
+
+	configIndex, err := protoutil.GetLastConfigIndexFromBlock(block)
+	if err != nil {
+		return errors.Wrapf(err, "failed getting config index from block number [%d] on channel [%s]", block.Header.Number, a.channelID)
+	}
+
+	if protoutil.IsConfigBlock(block) {
+		if configIndex != block.Header.Number {
+			return errors.Errorf("block [%d] is a config block but has config index [%d] that is different than expected (own number), on channel [%s]",
+				block.Header.Number, configIndex, a.channelID)
+		}
+		return nil
+	}
+
+	// For a data block: a.configBlockHeader may be nil when we start from common.Config and not a config block
+	if a.configBlockHeader != nil && configIndex != a.configBlockHeader.Number {
+		return errors.Errorf("block [%d] has config index [%d] that is different than expected: %d (current config), on channel [%s]",
+			block.Header.Number, configIndex, a.configBlockHeader.Number, a.channelID)
+	}
+
+	return nil
+}
+
+func (a *BlockVerificationAssistant) verifyHeader(block *common.Block) error {
+	if block == nil {
+		return errors.Errorf("block must be different from nil, channel=%s", a.channelID)
+	}
+	if block.Header == nil {
+		return errors.Errorf("invalid block, header must be different from nil, channel=%s", a.channelID)
+	}
+
+	expectedBlockNum := a.lastBlockHeader.Number + 1
+	if expectedBlockNum != block.Header.Number {
+		return errors.Errorf("expected block number is [%d] but actual block number inside block is [%d]", expectedBlockNum, block.Header.Number)
+	}
+
+	if len(a.lastBlockHeaderHash) != 0 {
+		if !bytes.Equal(block.Header.PreviousHash, a.lastBlockHeaderHash) {
+			return errors.Errorf("Header.PreviousHash of block [%d] is different from Hash(block.Header) of previous block, on channel [%s]", block.Header.Number, a.channelID)
+		}
+	}
+	return nil
+}