1150 lines
35 KiB
Nim
1150 lines
35 KiB
Nim
# beacon_chain
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# Copyright (c) 2018-2020 Status Research & Development GmbH
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# Licensed and distributed under either of
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# * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT).
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# * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
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# at your option. This file may not be copied, modified, or distributed except according to those terms.
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import
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# Standard library
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std/tables,
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# Status
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eth/db/kvstore,
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chronicles,
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nimcrypto/[hash, utils],
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serialization,
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json_serialization,
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# Internal
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./spec/[datatypes, digest, crypto],
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./ssz
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# Requirements
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# --------------------------------------------
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#
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# Overview of slashing and how it ties in with the rest of Eth2.0
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#
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# Phase 0 for humans - Validator responsibilities:
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# - https://notes.ethereum.org/@djrtwo/Bkn3zpwxB#Validator-responsibilities
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#
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# Phase 0 spec - Honest Validator - how to avoid slashing
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# - https://github.com/ethereum/eth2.0-specs/blob/v0.12.3/specs/phase0/validator.md#how-to-avoid-slashing
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#
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# In-depth reading on slashing conditions
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#
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# - Detecting slashing conditions https://hackmd.io/@n0ble/By897a5sH
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# - Open issue on writing a slashing detector https://github.com/ethereum/eth2.0-pm/issues/63
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# - Casper the Friendly Finality Gadget, Vitalik Buterin and Virgil Griffith
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# https://arxiv.org/pdf/1710.09437.pdf
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# Figure 2
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# An individual validator ν MUST NOT publish two distinct votes,
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# 〈ν,s1,t1,h(s1),h(t1) AND〈ν,s2,t2,h(s2),h(t2)〉,
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# such that either:
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# I. h(t1) = h(t2).
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# Equivalently, a validator MUST NOT publish two distinct votes for the same target height.
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# OR
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# II. h(s1) < h(s2) < h(t2) < h(t1).
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# Equivalently, a validator MUST NOT vote within the span of its other votes.
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# - Vitalik's annotated spec: https://github.com/ethereum/annotated-spec/blob/d8c51af84f9f309d91c37379c1fcb0810bc5f10a/phase0/beacon-chain.md#proposerslashing
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# 1. A proposer can get slashed for signing two distinct headers at the same slot.
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# 2. An attester can get slashed for signing
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# two attestations that together violate
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# the Casper FFG slashing conditions.
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# - https://github.com/ethereum/eth2.0-specs/blob/v0.12.3/specs/phase0/validator.md#ffg-vote
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# The "source" is the current_justified_epoch
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# The "target" is the current_epoch
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#
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# Reading on weak subjectivity
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# - https://notes.ethereum.org/@adiasg/weak-subjectvity-eth2
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# - https://www.symphonious.net/2019/11/27/exploring-ethereum-2-weak-subjectivity-period/
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# - https://ethresear.ch/t/weak-subjectivity-under-the-exit-queue-model/5187
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#
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# Reading of interop serialization format
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# - Import/export format: https://hackmd.io/@sproul/Bk0Y0qdGD
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# - Tests: https://github.com/eth2-clients/slashing-protection-interchange-tests
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#
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# Relaxation for Nimbus
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#
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# We are not building a slashing detector but only protecting
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# attached validator from slashing, hence we make the following assumptions
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#
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# 1. We only need to store specific validators signed blocks and attestations
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# 2. We assume that our node is synced past
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# the last finalized epoch
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# hence we only need to keep track of blocks and attestations
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# since the last finalized epoch and we don't need to care
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# about the weak subjectivity period.
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# i.e. if `Node.isSynced()` returns false
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# a node skips its validator duties and doesn't invoke slashing protection.
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# and `isSynced` syncs at least up to the blockchain last finalized epoch.
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#
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# Hence the database or key-value store should support
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#
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# Queries
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# 1. db.signedBlockExistsFor(validator, slot) -> bool
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# 2. db.attestationExistsFor(validator, target_epoch) -> bool
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# 3. db.attestationSurrounds(validator, source_epoch, target_epoch)
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#
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# Update
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# 1. db.registerBlock(validator, slot, block_root)
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# 2. db.registerAttestation(validator, source_epoch, target_epoch, attestation_root)
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#
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# Maintenance
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# 1. db.prune(finalized_epoch)
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#
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# Interop
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# 1. db.import(json)
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# 2. db.export(json)
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# 3. db.export(json, validator)
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# 4. db.export(json, seq[validator])
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# Technical Discussion
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# --------------------------------------------
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#
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# TODO: Merge with BeaconChainDB?
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# - https://stackoverflow.com/questions/21844479/multiple-databases-vs-single-database-with-logically-partitioned-data
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#
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# Reasons for merging
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# - Single database
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#
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# Reasons for not merging
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# - BeaconChainDB is about the beacon node itself
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# while slashing protection is about validators
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# - BeaconChainDB is append-only
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# while slashing protection will be pruned
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# at each finalization.
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# Hence we might want different backend in the future
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# - In a VC/BN split configuration the slashing protection
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# may be better attached to the VC. (VC: Validator Client, BN: Beacon Node)
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# - The slashing protection DB only held cryptographic hashes
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# and epoch/slot integers which are uncompressible
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# while BeaconChainDB is snappy-compressed.
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#
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# TODO: if we enshrine the split we likely want to use
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# a relational DB instead of KV-Store,
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# for efficient pruning and range queries support
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# DB primitives
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# --------------------------------------------
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# Implementation
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#
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# As mentioned in the technical discussion
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# we currently use a simple KV-store abstraction
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# with no range queries or iterators.
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#
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# To support our requirements
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# we store block proposals and attestations
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# as per-validator linked lists
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type
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SlashingProtectionDB* = ref object
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## Database storing the blocks attested
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## by validators attached to a beacon node
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## or validator client.
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backend: KvStoreRef
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BadVoteKind* = enum
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## Attestation bad vote kind
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# h: height (i.e. epoch for attestation, slot for blocks)
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# t: target
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# s: source
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# 1: existing attestations
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# 2: candidate attestation
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# Spec slashing condition
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DoubleVote # h(t1) = h(t2)
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SurroundedVote # h(s1) < h(s2) < h(t2) < h(t1)
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SurroundingVote # h(s2) < h(s1) < h(t1) < h(t2)
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# Non-spec, should never happen in a well functioning client
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TargetPrecedesSource # h(t1) < h(s1) - current epoch precedes last justified epoch
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BadVote* = object
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case kind*: BadVoteKind
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of DoubleVote:
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existingAttestation*: Eth2Digest
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of SurroundedVote, SurroundingVote:
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existingAttestationRoot*: Eth2Digest # Many roots might be in conflict
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sourceExisting*, targetExisting*: Epoch
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sourceSlashable*, targetSlashable*: Epoch
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of TargetPrecedesSource:
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discard
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SlotDesc = object
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# Using tuple instead of objects, crashes the Nim compiler
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# with SSZ serialization
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# Making this generic as well
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start, stop: Slot
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isInit: bool
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EpochDesc = object
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start, stop: Epoch
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isInit: bool
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KeysEpochs = object
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## Per-validator linked lists start/stop
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blockSlots: SlotDesc
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sourceEpochs: EpochDesc
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targetEpochs: EpochDesc
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SlashingKeyKind = enum
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# Note: source epochs are not unique
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# and so cannot be used to build a key
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kBlock
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kTargetEpoch
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kLinkedListMeta
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# Interchange format
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kGenesisValidatorRoot
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kNumValidators
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kValidator
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BlockNode = object
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prev, next: Slot
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# TODO distinct type for block root vs all other ETH2Digest
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block_root: Eth2Digest
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TargetEpochNode = object
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prev, next: Epoch
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# TODO distinct type for attestation root vs all other ETH2Digest
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attestation_root: Eth2Digest
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source: Epoch
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ValID = array[RawPubKeySize, byte]
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## This is the serialized byte representation
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## of a Validator Public Key.
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## Portable between Miracl/BLST
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## and limits serialization/deserialization call
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{.push raises: [Defect].}
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logScope:
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topics = "antislash"
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const UseSlashingProtection* {.booldefine.} = true
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when UseSlashingProtection:
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static: echo " Built with slashing protection"
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else:
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static: echo " Built without slashing protection"
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func subkey(
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kind: static SlashingKeyKind,
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validator: ValID,
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slot: Slot
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): array[RawPubKeySize+8, byte] =
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static: doAssert kind == kBlock
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# Big endian to get a naturally ascending order on slots in sorted indices
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result[0..<8] = toBytesBE(slot.uint64)
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# .. but 7 bytes should be enough for slots - in return, we get a nicely
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# rounded key length
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result[0] = byte ord(kBlock)
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result[8..<56] = validator
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func subkey(
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kind: static SlashingKeyKind,
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validator: ValID,
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epoch: Epoch
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): array[RawPubKeySize+8, byte] =
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static: doAssert kind == kTargetEpoch, "Got invalid kind " & $kind
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# Big endian to get a naturally ascending order on slots in sorted indices
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result[0..<8] = toBytesBE(epoch.uint64)
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# .. but 7 bytes should be enough for slots - in return, we get a nicely
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# rounded key length
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result[0] = byte ord(kind)
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result[8..<56] = validator
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func subkey(
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kind: static SlashingKeyKind,
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validator: ValID
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): array[RawPubKeySize+1, byte] =
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static: doAssert kind == kLinkedListMeta
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result[0] = byte ord(kLinkedListMeta)
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result[1 .. ^1] = validator
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func subkey(kind: static SlashingKeyKind): array[1, byte] =
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static: doAssert kind in {kNumValidators, kGenesisValidatorRoot}
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result[0] = byte ord(kind)
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func subkey(kind: static SlashingKeyKind, valIndex: uint32): array[5, byte] =
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static: doAssert kind == kValidator
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# Big endian to get a naturally ascending order on slots in sorted indices
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result[1..<5] = toBytesBE(valIndex)
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result[0] = byte ord(kind)
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proc put(db: SlashingProtectionDB, key: openarray[byte], v: auto) =
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db.backend.put(
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key,
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SSZ.encode(v)
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).expect("working database")
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proc get(db: SlashingProtectionDB,
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key: openarray[byte],
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T: typedesc): Opt[T] =
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const ExpectedNodeSszSize = block:
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when T is BlockNode:
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2*sizeof(Epoch) + sizeof(Eth2Digest)
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elif T is TargetEpochNode:
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2*sizeof(Epoch) + sizeof(Eth2Digest) + sizeof(Epoch)
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elif T is KeysEpochs:
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2*sizeof(Slot) + 4*sizeof(Epoch) + 3*sizeof(bool)
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elif T is Eth2Digest:
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sizeof(Eth2Digest)
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elif T is uint32:
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sizeof(uint32)
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elif T is ValidatorPubKey:
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RawPubKeySize
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else:
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{.error: "Invalid database node type: " & $T.}
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## SSZ serialization is packed
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## However in-memory, BlockNode, TargetEpochNode
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## might be bigger due to alignment/compiler padding
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var res: Opt[T]
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proc decode(data: openArray[byte]) =
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# We are capturing "result" and "T" from outer scope
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# And allocating on the heap which are not ideal
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# from a safety and performance point of view.
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try:
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if data.len == ExpectedNodeSszSize:
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when T is ValidatorPubKey:
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# symbol resolution bug
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# SSZ.decode doesn't see "fromSSZBytes"
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res.ok ValidatorPubKey.fromSszBytes(data)
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else:
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res.ok SSZ.decode(data, T) # captures from `get` scope
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else:
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# If the data can't be deserialized, it could be because it's from a
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# version of the software that uses a different SSZ encoding
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warn "Unable to deserialize data, old database?",
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typ = $T,
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dataLen = data.len,
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expectedSize = ExpectedNodeSszSize
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discard
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except SerializationError as e:
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# If the data can't be deserialized, it could be because it's from a
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# version of the software that uses a different SSZ encoding
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warn "Unable to deserialize data, old database?",
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typ = $T,
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dataLen = data.len,
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expectedSize = ExpectedNodeSszSize
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discard
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discard db.backend.get(key, decode).expect("working database")
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res
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proc setGenesis(db: SlashingProtectionDB, genesis_validator_root: Eth2Digest) =
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# Workaround SSZ / nim-serialization visibility issue
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# "template WriterType(T: type SSZ): type"
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# by having a non-generic proc
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db.put(
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subkey(kGenesisValidatorRoot),
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genesis_validator_root
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)
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proc init*(
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T: type SlashingProtectionDB,
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genesis_validator_root: Eth2Digest,
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backend: KVStoreRef): SlashingProtectionDB =
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when UseSlashingProtection:
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result = T(backend: backend)
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result.setGenesis(genesis_validator_root)
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proc close*(db: SlashingProtectionDB) =
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when UseSlashingProtection:
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discard db.backend.close()
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# DB Queries
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# --------------------------------------------
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proc checkSlashableBlockProposalImpl(
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db: SlashingProtectionDB,
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validator: ValidatorPubKey,
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slot: Slot
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): Result[void, Eth2Digest] =
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## Returns an error if the specified validator
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## already proposed a block for the specified slot.
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## This would lead to slashing.
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## The error contains the blockroot that was already proposed
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##
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## Returns success otherwise
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# TODO distinct type for the result block root
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let valID = validator.toRaw()
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let foundBlock = db.get(
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subkey(kBlock, valID, slot),
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BlockNode
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)
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if foundBlock.isNone():
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return ok()
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return err(foundBlock.unsafeGet().block_root)
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proc checkSlashableBlockProposal*(
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db: SlashingProtectionDB,
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validator: ValidatorPubKey,
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slot: Slot
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): Result[void, Eth2Digest] =
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## Returns an error if the specified validator
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## already proposed a block for the specified slot.
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## This would lead to slashing.
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## The error contains the blockroot that was already proposed
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##
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## Returns success otherwise
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# TODO distinct type for the result block root
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when UseSlashingProtection:
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checkSlashableBlockProposalImpl(
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db, validator, slot
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)
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else:
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ok()
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proc checkSlashableAttestationImpl(
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db: SlashingProtectionDB,
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validator: ValidatorPubKey,
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source: Epoch,
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target: Epoch
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): Result[void, BadVote] =
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## Returns an error if the specified validator
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## already proposed a block for the specified slot.
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## This would lead to slashing.
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## The error contains the blockroot that was already proposed
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##
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## Returns success otherwise
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# TODO distinct type for the result attestation root
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let valID = validator.toRaw()
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# Sanity
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# ---------------------------------
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if source > target:
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return err(BadVote(kind: TargetPrecedesSource))
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# Casper FFG 1st slashing condition
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# Detect h(t1) = h(t2)
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# ---------------------------------
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let foundAttestation = db.get(
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subkey(kTargetEpoch, valID, target),
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TargetEpochNode
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)
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if foundAttestation.isSome():
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# Logged by caller
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return err(BadVote(
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kind: DoubleVote,
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existingAttestation: foundAttestation.unsafeGet().attestation_root
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))
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# TODO: we hack KV-store range queries
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# ---------------------------------
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let maybeLL = db.get(
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subkey(kLinkedListMeta, valID),
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KeysEpochs
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)
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if maybeLL.isNone:
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info "No slashing protection data - first attestation?",
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validator = validator,
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attSource = source,
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attTarget = target
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return ok()
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let ll = maybeLL.unsafeGet()
|
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if not ll.targetEpochs.isInit:
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info "No attestation slashing protection data - first attestation?",
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validator = validator,
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attSource = source,
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attTarget = target
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return ok()
|
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|
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# Chain reorg
|
||
# Detect h(s2) < h(s1)
|
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# If the candidate attestation source precedes
|
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# source(s) we have in the SlashingProtectionDB
|
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# we have a chain reorg
|
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# ---------------------------------
|
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if source < ll.sourceEpochs.stop:
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warn "Detected a chain reorg",
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earliestJustifiedEpoch = ll.sourceEpochs.start,
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oldestJustifiedEpoch = ll.sourceEpochs.stop,
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reorgJustifiedEpoch = source,
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monitoredValidator = validator
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|
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# Casper FFG 2nd slashing condition
|
||
# -> Surrounded vote
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# Detect h(s1) < h(s2) < h(t2) < h(t1)
|
||
# ---------------------------------
|
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# Casper FFG 2nd slashing condition
|
||
# -> Surrounding vote
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# Detect h(s2) < h(s1) < h(t1) < h(t2)
|
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# ---------------------------------
|
||
|
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template s2: untyped = source
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template t2: untyped = target
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|
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# We start from the final target epoch
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var t1: Epoch
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var t1Node: TargetEpochNode
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|
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t1 = ll.targetEpochs.stop
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t1Node = db.get(
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subkey(kTargetEpoch, valID, t1),
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TargetEpochNode
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# bug in Nim results, ".e" field inaccessible
|
||
# ).expect("Consistent linked-list in DB")
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||
).unsafeGet()
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template s1: untyped = t1Node.source
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template ar1: untyped = t1Node.attestation_root
|
||
|
||
# TODO: optimize so we don't scan the whole linked list
|
||
while true:
|
||
if s2 < s1 and s1 < t1 and t1 < t2:
|
||
# s2 < s1 < t1 < t2
|
||
# Logged by caller
|
||
return err(BadVote(
|
||
kind: SurroundingVote,
|
||
existingAttestationRoot: ar1,
|
||
sourceExisting: s1,
|
||
targetExisting: t1,
|
||
sourceSlashable: s2,
|
||
targetSlashable: t2
|
||
))
|
||
elif s1 < s2 and s2 < t2 and t2 < t1:
|
||
# s1 < s2 < t2 < t1
|
||
# Logged by caller
|
||
return err(BadVote(
|
||
kind: SurroundedVote,
|
||
existingAttestationRoot: ar1,
|
||
sourceExisting: s1,
|
||
targetExisting: t1,
|
||
sourceSlashable: s2,
|
||
targetSlashable: t2
|
||
))
|
||
|
||
# Next iteration
|
||
if t1Node.prev == default(Epoch) or
|
||
t1Node.prev == ll.targetEpochs.stop:
|
||
return ok()
|
||
else:
|
||
t1 = t1Node.prev
|
||
t1Node = db.get(
|
||
subkey(kTargetEpoch, valID, t1Node.prev),
|
||
TargetEpochNode
|
||
# bug in Nim results, ".e" field inaccessible
|
||
# ).expect("Consistent linked-list in DB")
|
||
).unsafeGet()
|
||
|
||
doAssert false, "Unreachable"
|
||
|
||
proc checkSlashableAttestation*(
|
||
db: SlashingProtectionDB,
|
||
validator: ValidatorPubKey,
|
||
source: Epoch,
|
||
target: Epoch
|
||
): Result[void, BadVote] =
|
||
## Returns an error if the specified validator
|
||
## already proposed a block for the specified slot.
|
||
## This would lead to slashing.
|
||
## The error contains the blockroot that was already proposed
|
||
##
|
||
## Returns success otherwise
|
||
# TODO distinct type for the result attestation root
|
||
when UseSlashingProtection:
|
||
checkSlashableAttestationImpl(
|
||
db, validator, source, target
|
||
)
|
||
else:
|
||
ok()
|
||
|
||
# DB update
|
||
# --------------------------------------------
|
||
|
||
proc registerValidator(db: SlashingProtectionDB, validator: ValidatorPubKey) =
|
||
## Add a new validator to the database
|
||
## Assumes the validator does not exist
|
||
let maybeNumVals = db.get(
|
||
subkey(kNumValidators),
|
||
uint32
|
||
)
|
||
var valIndex = 0'u32
|
||
if maybeNumVals.isNone():
|
||
db.put(subkey(kNumValidators), 1'u32)
|
||
else:
|
||
valIndex = maybeNumVals.unsafeGet()
|
||
db.put(subkey(kNumValidators), valIndex + 1)
|
||
|
||
db.put(subkey(kValidator, valIndex), validator)
|
||
|
||
proc registerBlockImpl(
|
||
db: SlashingProtectionDB,
|
||
validator: ValidatorPubKey,
|
||
slot: Slot, block_root: Eth2Digest) =
|
||
## Add a block to the slashing protection DB
|
||
## `checkSlashableBlockProposal` MUST be run
|
||
## before to ensure no overwrite.
|
||
|
||
let valID = validator.toRaw()
|
||
|
||
# We want to keep the linked-list ordered
|
||
# to ease pruning.
|
||
# TODO: DB instead of KV-store,
|
||
# at the very least we should isolate that logic
|
||
let maybeLL = db.get(
|
||
subkey(kLinkedListMeta, valID),
|
||
KeysEpochs
|
||
)
|
||
|
||
if maybeLL.isNone:
|
||
info "No slashing protection data - initiating block tracking for validator",
|
||
validator = validator
|
||
|
||
db.registerValidator(validator)
|
||
|
||
let node = BlockNode(
|
||
block_root: block_root
|
||
)
|
||
db.put(subkey(kBlock, valID, slot), node)
|
||
db.put(
|
||
subkey(kLinkedListMeta, valID),
|
||
KeysEpochs(
|
||
blockSlots: SlotDesc(start: slot, stop: slot, isInit: true),
|
||
# targetEpochs.isInit will be false
|
||
)
|
||
)
|
||
return
|
||
|
||
var ll = maybeLL.unsafeGet()
|
||
var cur = ll.blockSlots.stop
|
||
if not ll.blockSlots.isInit:
|
||
let node = BlockNode(
|
||
block_root: block_root
|
||
)
|
||
ll.blockSlots = SlotDesc(start: slot, stop: slot, isInit: true)
|
||
db.put(subkey(kBlock, valID, slot), node)
|
||
# TODO: what if crash here?
|
||
db.put(subkey(kLinkedListMeta, valID), ll)
|
||
return
|
||
|
||
if cur < slot:
|
||
# Adding a block later than all known blocks
|
||
let node = BlockNode(
|
||
prev: cur,
|
||
block_root: block_root
|
||
)
|
||
var prevNode = db.get(
|
||
subkey(kBlock, valID, cur),
|
||
BlockNode
|
||
# bug in Nim results, ".e" field inaccessible
|
||
# ).expect("Consistent linked-list in DB")
|
||
).unsafeGet()
|
||
prevNode.next = slot
|
||
ll.blockSlots.stop = slot
|
||
db.put(subkey(kBlock, valID, slot), node)
|
||
db.put(subkey(kBlock, valID, cur), prevNode)
|
||
# TODO: what if crash here?
|
||
db.put(subkey(kLinkedListMeta, valID), ll)
|
||
return
|
||
|
||
# TODO: we likely want a proper DB or better KV-store high-level API
|
||
# in the future.
|
||
while true:
|
||
var curNode = db.get(
|
||
subkey(kBlock, valID, cur),
|
||
BlockNode
|
||
# bug in Nim results, ".e" field inaccessible
|
||
# ).expect("Consistent linked-list in DB")
|
||
).unsafeGet()
|
||
|
||
if curNode.prev == ll.blockSlots.start:
|
||
# Reached the beginning
|
||
# Change: Metadata.start <-> cur
|
||
# to: Metadata.start <-> new <-> cur
|
||
# This should happen only if registerBlock
|
||
# is called out-of-order
|
||
warn "Validator proposal in the past - out-of-order antislash registration?",
|
||
validator = validator,
|
||
slot = slot,
|
||
blockroot = blockroot,
|
||
earliestBlockProposalSlotInDB = ll.blockSlots.start,
|
||
latestBlockProposalSlotInDB = ll.blockSlots.stop
|
||
var node = BlockNode(
|
||
prev: ll.blockSlots.start,
|
||
next: cur,
|
||
block_root: block_root
|
||
)
|
||
ll.blockSlots.start = slot
|
||
curNode.prev = slot
|
||
db.put(subkey(kBlock, valID, slot), node)
|
||
# TODO: what if crash here?
|
||
db.put(subkey(kBlock, valID, cur), curNode)
|
||
db.put(subkey(kLinkedListMeta, valID), ll)
|
||
return
|
||
elif slot > curNode.prev:
|
||
# Reached: prev < slot < cur
|
||
# Change: prev <-> cur
|
||
# to: prev <-> new <-> cur
|
||
let prev = curNode.prev
|
||
var node = BlockNode(
|
||
prev: prev, next: cur,
|
||
block_root: block_root
|
||
)
|
||
var prevNode = db.get(
|
||
subkey(kBlock, valID, prev),
|
||
BlockNode
|
||
# bug in Nim results, ".e" field inaccessible
|
||
# ).expect("Consistent linked-list in DB")
|
||
).unsafeGet()
|
||
prevNode.next = slot
|
||
curNode.prev = slot
|
||
db.put(subkey(kBlock, valID, slot), node)
|
||
# TODO: what if crash here?
|
||
db.put(subkey(kBlock, valID, cur), curNode)
|
||
db.put(subkey(kBlock, valID, prev), prevNode)
|
||
return
|
||
|
||
# Previous
|
||
cur = curNode.prev
|
||
curNode = db.get(
|
||
subkey(kBlock, valID, cur),
|
||
BlockNode
|
||
# bug in Nim results, ".e" field inaccessible
|
||
# ).expect("Consistent linked-list in DB")
|
||
).unsafeGet()
|
||
|
||
proc registerBlock*(
|
||
db: SlashingProtectionDB,
|
||
validator: ValidatorPubKey,
|
||
slot: Slot, block_root: Eth2Digest) =
|
||
## Add a block to the slashing protection DB
|
||
## `checkSlashableBlockProposal` MUST be run
|
||
## before to ensure no overwrite.
|
||
when UseSlashingProtection:
|
||
registerBlockImpl(
|
||
db, validator, slot, block_root
|
||
)
|
||
else:
|
||
discard
|
||
|
||
proc registerAttestationImpl(
|
||
db: SlashingProtectionDB,
|
||
validator: ValidatorPubKey,
|
||
source, target: Epoch,
|
||
attestation_root: Eth2Digest) =
|
||
## Add an attestation to the slashing protection DB
|
||
## `checkSlashableAttestation` MUST be run
|
||
## before to ensure no overwrite.
|
||
|
||
let valID = validator.toRaw()
|
||
|
||
# We want to keep the linked-list ordered
|
||
# to ease pruning.
|
||
# TODO: DB instead of KV-store,
|
||
# at the very least we should isolate that logic
|
||
let maybeLL = db.get(
|
||
subkey(kLinkedListMeta, valID),
|
||
KeysEpochs
|
||
)
|
||
|
||
if maybeLL.isNone:
|
||
info "No slashing protection data - initiating attestation tracking for validator",
|
||
validator = validator
|
||
|
||
db.registerValidator(validator)
|
||
|
||
let node = TargetEpochNode(
|
||
source: source,
|
||
attestation_root: attestation_root
|
||
)
|
||
db.put(subkey(kTargetEpoch, valID, target), node)
|
||
db.put(
|
||
subkey(kLinkedListMeta, valID),
|
||
KeysEpochs(
|
||
# blockSlots.isInit will be false
|
||
sourceEpochs: EpochDesc(start: source, stop: source, isInit: true),
|
||
targetEpochs: EpochDesc(start: target, stop: target, isInit: true)
|
||
)
|
||
)
|
||
return
|
||
|
||
var ll = maybeLL.unsafeGet()
|
||
var cur = ll.targetEpochs.stop
|
||
if not ll.targetEpochs.isInit:
|
||
let node = TargetEpochNode(
|
||
attestation_root: attestation_root,
|
||
source: source
|
||
)
|
||
ll.targetEpochs = EpochDesc(start: target, stop: target, isInit: true)
|
||
ll.sourceEpochs = EpochDesc(start: source, stop: source, isInit: true)
|
||
db.put(subkey(kTargetEpoch, valID, target), node)
|
||
# TODO: what if crash here?
|
||
db.put(subkey(kLinkedListMeta, valID), ll)
|
||
return
|
||
|
||
block: # Update source epoch
|
||
if ll.sourceEpochs.stop < source:
|
||
ll.sourceEpochs.stop = source
|
||
if source < ll.sourceEpochs.start:
|
||
ll.sourceEpochs.start = source
|
||
|
||
if cur < target:
|
||
# Adding an attestation later than all known blocks
|
||
let node = TargetEpochNode(
|
||
prev: cur,
|
||
source: source,
|
||
attestation_root: attestation_root
|
||
)
|
||
var prevNode = db.get(
|
||
subkey(kTargetEpoch, valID, cur),
|
||
TargetEpochNode
|
||
# bug in Nim results, ".e" field inaccessible
|
||
# ).expect("Consistent linked-list in DB")
|
||
).unsafeGet()
|
||
prevNode.next = target
|
||
ll.targetEpochs.stop = target
|
||
db.put(subkey(kTargetEpoch, valID, target), node)
|
||
db.put(subkey(kTargetEpoch, valID, cur), prevNode)
|
||
# TODO: what if crash here?
|
||
db.put(subkey(kLinkedListMeta, valID), ll)
|
||
return
|
||
|
||
# TODO: we likely want a proper DB or better KV-store high-level API
|
||
# in the future.
|
||
while true:
|
||
var curNode = db.get(
|
||
subkey(kTargetEpoch, valID, cur),
|
||
TargetEpochNode
|
||
# bug in Nim results, ".e" field inaccessible
|
||
# ).expect("Consistent linked-list in DB")
|
||
).unsafeGet()
|
||
if curNode.prev == ll.targetEpochs.start:
|
||
# Reached the beginning
|
||
# Change: Metadata.start <-> cur
|
||
# to: Metadata.start <-> new <-> cur
|
||
# This should happen only if registerAttestation
|
||
# is called out-of-order or if the validator
|
||
# changes its vote for an earlier fork than its latest vote
|
||
warn "Validator vote targeting the past - out-of-order antislash registration or chain reorg?",
|
||
validator = validator,
|
||
source_epoch = source,
|
||
target_epoch = target,
|
||
attestation_root = attestation_root
|
||
var node = TargetEpochNode(
|
||
prev: ll.targetEpochs.start,
|
||
next: cur,
|
||
source: source,
|
||
attestation_root: attestation_root
|
||
)
|
||
ll.targetEpochs.start = target
|
||
curNode.prev = target
|
||
db.put(subkey(kTargetEpoch, valID, target), node)
|
||
# TODO: what if crash here?
|
||
db.put(subkey(kTargetEpoch, valID, cur), curNode)
|
||
db.put(subkey(kLinkedListMeta, valID), ll)
|
||
return
|
||
elif target > curNode.prev:
|
||
# Reached: prev < target < cur
|
||
# Change: prev <-> cur
|
||
# to: prev <-> new <-> cur
|
||
let prev = curNode.prev
|
||
var node = TargetEpochNode(
|
||
prev: prev, next: cur,
|
||
source: source,
|
||
attestation_root: attestation_root
|
||
)
|
||
var prevNode = db.get(
|
||
subkey(kTargetEpoch, valID, prev),
|
||
TargetEpochNode
|
||
# bug in Nim results, ".e" field inaccessible
|
||
# ).expect("Consistent linked-list in DB")
|
||
).unsafeGet()
|
||
prevNode.next = target
|
||
curNode.prev = target
|
||
db.put(subkey(kTargetEpoch, valID, target), node)
|
||
# TODO: what if crash here?
|
||
db.put(subkey(kTargetEpoch, valID, cur), curNode)
|
||
db.put(subkey(kTargetEpoch, valID, prev), prevNode)
|
||
return
|
||
|
||
# Previous
|
||
cur = curNode.prev
|
||
curNode = db.get(
|
||
subkey(kTargetEpoch, valID, cur),
|
||
TargetEpochNode
|
||
# bug in Nim results, ".e" field inaccessible
|
||
# ).expect("Consistent linked-list in DB")
|
||
).unsafeGet()
|
||
|
||
proc registerAttestation*(
|
||
db: SlashingProtectionDB,
|
||
validator: ValidatorPubKey,
|
||
source, target: Epoch,
|
||
attestation_root: Eth2Digest) =
|
||
## Add an attestation to the slashing protection DB
|
||
## `checkSlashableAttestation` MUST be run
|
||
## before to ensure no overwrite.
|
||
when UseSlashingProtection:
|
||
registerAttestationImpl(
|
||
db, validator, source, target, attestation_root
|
||
)
|
||
else:
|
||
discard
|
||
|
||
# Debug tools
|
||
# --------------------------------------------
|
||
|
||
proc dumpBlocks*(
|
||
db: SlashingProtectionDB,
|
||
validator: ValidatorPubKey
|
||
): string =
|
||
## Dump the linked list of blocks proposd by a validator in a string
|
||
var blocks: seq[BlockNode]
|
||
|
||
let valID = validator.toRaw
|
||
let maybeLL = db.get(
|
||
subkey(kLinkedListMeta, valID),
|
||
KeysEpochs
|
||
)
|
||
if maybeLL.isNone:
|
||
return "No blocks in slashing protection DB for validator " & $validator
|
||
|
||
let ll = maybeLL.unsafeGet()
|
||
doAssert ll.blockSlots.isInit
|
||
|
||
var cur = ll.blockSlots.stop
|
||
|
||
while cur != ll.blockSlots.start:
|
||
blocks.add db.get(
|
||
subkey(kBlock, valID, cur),
|
||
BlockNode
|
||
).unsafeGet()
|
||
|
||
cur = blocks[^1].prev
|
||
|
||
blocks.add db.get(
|
||
subkey(kBlock, valID, ll.blockSlots.start),
|
||
BlockNode
|
||
).unsafeGet()
|
||
|
||
return $blocks
|
||
|
||
proc dumpAttestations*(
|
||
db: SlashingProtectionDB,
|
||
validator: ValidatorPubKey
|
||
): string =
|
||
## Dump the linked list of blocks proposd by a validator in a string
|
||
var attestations: seq[TargetEpochNode]
|
||
|
||
let valID = validator.toRaw
|
||
let maybeLL = db.get(
|
||
subkey(kLinkedListMeta, valID),
|
||
KeysEpochs
|
||
)
|
||
if maybeLL.isNone:
|
||
return "No blocks in slashing protection DB for validator " & $validator
|
||
|
||
let ll = maybeLL.unsafeGet()
|
||
doAssert ll.targetEpochs.isInit
|
||
|
||
var cur = ll.targetEpochs.stop
|
||
|
||
while cur != ll.targetEpochs.start:
|
||
attestations.add db.get(
|
||
subkey(kTargetEpoch, valID, cur),
|
||
TargetEpochNode
|
||
).unsafeGet()
|
||
|
||
cur = attestations[^1].prev
|
||
|
||
attestations.add db.get(
|
||
subkey(kTargetEpoch, valID, ll.targetEpochs.start),
|
||
TargetEpochNode
|
||
).unsafeGet()
|
||
|
||
return $attestations
|
||
|
||
# DB maintenance
|
||
# --------------------------------------------
|
||
# TODO: pruning
|
||
# Note that the complete interchange format
|
||
# requires all proposals/attestations ever and so prevent pruning.
|
||
|
||
# Interchange
|
||
# --------------------------------------------
|
||
|
||
type
|
||
SPDIF = object
|
||
## Slashing Protection Database Interchange Format
|
||
metadata: SPDIF_Meta
|
||
data: seq[SPDIF_Validator]
|
||
|
||
Eth2Digest0x = distinct Eth2Digest
|
||
## The spec mandates "0x" prefix on serialization
|
||
## So we need to set custom read/write
|
||
PubKey0x = distinct ValidatorPubKey
|
||
## The spec mandates "0x" prefix on serialization
|
||
## So we need to set custom read/write
|
||
|
||
SPDIF_Meta = object
|
||
interchange_format: string
|
||
interchange_format_version: string
|
||
genesis_validator_root: Eth2Digest0x
|
||
|
||
SPDIF_Validator = object
|
||
pubkey: PubKey0x
|
||
signed_blocks: seq[SPDIF_SignedBlock]
|
||
signed_attestations: seq[SPDIF_SignedAttestation]
|
||
|
||
SPDIF_SignedBlock = object
|
||
slot: Slot
|
||
signing_root: Eth2Digest0x # compute_signing_root(block, domain)
|
||
|
||
SPDIF_SignedAttestation = object
|
||
source_epoch: Epoch
|
||
target_epoch: Epoch
|
||
signing_root: Eth2Digest0x # compute_signing_root(attestation, domain)
|
||
|
||
proc writeValue*(writer: var JsonWriter, value: PubKey0x)
|
||
{.inline, raises: [IOError, Defect].} =
|
||
writer.writeValue("0x" & value.ValidatorPubKey.toHex())
|
||
|
||
proc readValue*(reader: var JsonReader, value: var PubKey0x)
|
||
{.raises: [SerializationError, IOError, Defect].} =
|
||
let key = ValidatorPubKey.fromHex(reader.readValue(string))
|
||
if key.isOk:
|
||
value = PubKey0x key.get
|
||
else:
|
||
# TODO: Can we provide better diagnostic?
|
||
raiseUnexpectedValue(reader, "Valid hex-encoded public key expected")
|
||
|
||
proc writeValue*(w: var JsonWriter, a: Eth2Digest0x)
|
||
{.inline, raises: [IOError, Defect].} =
|
||
w.writeValue "0x" & a.Eth2Digest.data.toHex(lowercase = true)
|
||
|
||
proc readValue*(r: var JsonReader, a: var Eth2Digest0x)
|
||
{.raises: [SerializationError, IOError, Defect].} =
|
||
try:
|
||
a = Eth2Digest0x fromHex(Eth2Digest, r.readValue(string))
|
||
except ValueError:
|
||
raiseUnexpectedValue(r, "Hex string expected")
|
||
|
||
proc toSPDIF*(db: SlashingProtectionDB, path: string)
|
||
{.raises: [IOError, Defect].} =
|
||
## Export the full slashing protection database
|
||
## to a json the Slashing Protection Database Interchange (Complete) Format
|
||
var extract: SPDIF
|
||
extract.metadata.interchange_format = "complete"
|
||
extract.metadata.interchange_format_version = "3"
|
||
extract.metadata.genesis_validator_root = Eth2Digest0x db.get(
|
||
subkey(kGenesisValidatorRoot), ETH2Digest
|
||
# Bug in results.nim
|
||
# ).expect("Slashing Protection requires genesis_validator_root at init")
|
||
).unsafeGet()
|
||
|
||
let numValidators = db.get(
|
||
subkey(kNumValidators),
|
||
uint32
|
||
).get(otherwise = 0'u32)
|
||
|
||
for i in 0'u32 ..< numValidators:
|
||
var validator: SPDIF_Validator
|
||
validator.pubkey = PubKey0x db.get(
|
||
subkey(kValidator, i),
|
||
ValidatorPubKey
|
||
).unsafeGet()
|
||
|
||
let valID = validator.pubkey.ValidatorPubKey.toRaw()
|
||
let ll = db.get(
|
||
subkey(kLinkedListMeta, valID),
|
||
KeysEpochs
|
||
).unsafeGet()
|
||
|
||
if ll.blockSlots.isInit:
|
||
var curSlot = ll.blockSlots.start
|
||
while true:
|
||
let node = db.get(
|
||
subkey(kBlock, valID, curSlot),
|
||
BlockNode
|
||
).unsafeGet()
|
||
|
||
validator.signed_blocks.add SPDIF_SignedBlock(
|
||
slot: curSlot,
|
||
signing_root: Eth2Digest0x node.block_root
|
||
)
|
||
|
||
if curSlot == ll.blockSlots.stop:
|
||
break
|
||
else:
|
||
curSlot = node.next
|
||
|
||
if ll.targetEpochs.isInit:
|
||
var curEpoch = ll.targetEpochs.start
|
||
var count = 0
|
||
while true:
|
||
let node = db.get(
|
||
subkey(kTargetEpoch, valID, curEpoch),
|
||
TargetEpochNode
|
||
).unsafeGet()
|
||
|
||
validator.signed_attestations.add SPDIF_SignedAttestation(
|
||
source_epoch: node.source, target_epoch: curEpoch,
|
||
signing_root: Eth2Digest0x node.attestation_root
|
||
)
|
||
|
||
if curEpoch == ll.targetEpochs.stop:
|
||
break
|
||
else:
|
||
curEpoch = node.next
|
||
|
||
inc count
|
||
doAssert count < 5
|
||
|
||
# Update extract without reallocating seqs
|
||
# by manually transferring ownership
|
||
extract.data.setLen(extract.data.len + 1)
|
||
shallowCopy(extract.data[^1], validator)
|
||
|
||
Json.saveFile(path, extract, pretty = true)
|
||
echo "Exported slashing protection DB to '", path, "'"
|
||
|
||
proc fromSPDIF*(db: SlashingProtectionDB, path: string): bool
|
||
{.raises: [SerializationError, IOError, Defect].} =
|
||
## Import a (Complete) Slashing Protection Database Interchange Format
|
||
## file into the specified slahsing protection DB
|
||
##
|
||
## The database must be initialized.
|
||
## The genesis_validator_root must match or
|
||
## the DB must have a zero root
|
||
|
||
let extract = Json.loadFile(path, SPDIF)
|
||
|
||
doAssert not db.isNil, "The Slashing Protection DB must be initialized."
|
||
doAssert not db.backend.isNil, "The Slashing Protection DB must be initialized."
|
||
|
||
let dbGenValRoot = db.get(
|
||
subkey(kGenesisValidatorRoot), ETH2Digest
|
||
).unsafeGet()
|
||
|
||
if dbGenValRoot != default(Eth2Digest) and
|
||
dbGenValRoot != extract.metadata.genesis_validator_root.Eth2Digest:
|
||
echo "The slashing protection database and imported file refer to different blockchains."
|
||
return false
|
||
|
||
if dbGenValRoot == default(Eth2Digest):
|
||
db.put(
|
||
subkey(kGenesisValidatorRoot),
|
||
extract.metadata.genesis_validator_root.Eth2Digest
|
||
)
|
||
|
||
for v in 0 ..< extract.data.len:
|
||
for b in 0 ..< extract.data[v].signed_blocks.len:
|
||
db.registerBlock(
|
||
extract.data[v].pubkey.ValidatorPubKey,
|
||
extract.data[v].signed_blocks[b].slot,
|
||
extract.data[v].signed_blocks[b].signing_root.Eth2Digest
|
||
)
|
||
for a in 0 ..< extract.data[v].signed_attestations.len:
|
||
db.registerAttestation(
|
||
extract.data[v].pubkey.ValidatorPubKey,
|
||
extract.data[v].signed_attestations[a].source_epoch,
|
||
extract.data[v].signed_attestations[a].target_epoch,
|
||
extract.data[v].signed_attestations[a].signing_root.Eth2Digest
|
||
)
|
||
|
||
return true
|