Acquire `per_peer_state` `write` lock earlier in `ChannelManager::write` #2998

tnull · 2024-04-17T10:03:00Z

Previously, we would hold the per_peer_state read lock during the serialization of channel objects. While this might have reduced lock congestion minimally, we also calculated the number of serializable peers in this phase, only to use it later after dropping and reacquiring the per_peer_state write lock.

This could potentially result in inconsistiencies if the serializable_peer_count would change after we dropped the read lock but before we acquired the write lock.

To mitigate the issue we just acquire the write lock ealier and hold it for the remainder of ChannelManager::write.

Previously, we would hold the `per_peer_state` `read` lock during the serialization of channel objects. While this might have reduced lock congestion minimally, we also calculated the number of serializable peers in this phase, only to use it later after dropping and reacquiring the `per_peer_state` `write` lock. This could potentially result in inconsistiencies if the `serializable_peer_count` would change after we dropped the `read` lock but before we acquired the `write` lock. To mitigate the issue we just acquire the `write` lock ealier and hold it for the remainder of `ChannelManager::write`.

G8XSU · 2024-04-18T18:35:21Z

lightning/src/ln/channelmanager.rs

@@ -11035,9 +11035,10 @@ where
 			best_block.block_hash.write(writer)?;
 		}

+		let per_peer_state = self.per_peer_state.write().unwrap();
+
 		let mut serializable_peer_count: u64 = 0;
 		{


nit: looks like scope braces were in place for the read lock, is there any pending reason for them?

Yeah, I first had them removed and unindented the block, but found it still reads better if we keep the grouping, IMO.

Yes makes sense!

v0.0.123 - May 08, 2024 - "BOLT12 Dust Sweeping" API Updates =========== * To reduce risk of force-closures and improve HTLC reliability the default dust exposure limit has been increased to `MaxDustHTLCExposure::FeeRateMultiplier(10_000)`. Users with existing channels might want to consider using `ChannelManager::update_channel_config` to apply the new default (lightningdevkit#3045). * `ChainMonitor::archive_fully_resolved_channel_monitors` is now provided to remove from memory `ChannelMonitor`s that have been fully resolved on-chain and are now not needed. It uses the new `Persist::archive_persisted_channel` to inform the storage layer that such a monitor should be archived (lightningdevkit#2964). * An `OutputSweeper` is now provided which will automatically sweep `SpendableOutputDescriptor`s, retrying until the sweep confirms (lightningdevkit#2825). * After initiating an outbound channel, a peer disconnection no longer results in immediate channel closure. Rather, if the peer is reconnected before the channel times out LDK will automatically retry opening it (lightningdevkit#2725). * `PaymentPurpose` now has separate variants for BOLT12 payments, which include fields from the `invoice_request` as well as the `OfferId` (lightningdevkit#2970). * `ChannelDetails` now includes a list of in-flight HTLCs (lightningdevkit#2442). * `Event::PaymentForwarded` now includes `skimmed_fee_msat` (lightningdevkit#2858). * The `hashbrown` dependency has been upgraded and the use of `ahash` as the no-std hash table hash function has been removed. As a consequence, LDK's `Hash{Map,Set}`s no longer feature several constructors when LDK is built with no-std; see the `util::hash_tables` module instead. On platforms that `getrandom` supports, setting the `possiblyrandom/getrandom` feature flag will ensure hash tables are resistant to HashDoS attacks, though the `possiblyrandom` crate should detect most common platforms (lightningdevkit#2810, lightningdevkit#2891). * `ChannelMonitor`-originated requests to the `ChannelSigner` can now fail and be retried using `ChannelMonitor::signer_unblocked` (lightningdevkit#2816). * `SpendableOutputDescriptor::to_psbt_input` now includes the `witness_script` where available as well as new proprietary data which can be used to re-derive some spending keys from the base key (lightningdevkit#2761, lightningdevkit#3004). * `OutPoint::to_channel_id` has been removed in favor of `ChannelId::v1_from_funding_outpoint` in preparation for v2 channels with a different `ChannelId` derivation scheme (lightningdevkit#2797). * `PeerManager::get_peer_node_ids` has been replaced with `list_peers` and `peer_by_node_id`, which provide more details (lightningdevkit#2905). * `Bolt11Invoice::get_payee_pub_key` is now provided (lightningdevkit#2909). * `Default[Message]Router` now take an `entropy_source` argument (lightningdevkit#2847). * `ClosureReason::HTLCsTimedOut` has been separated out from `ClosureReason::HolderForceClosed` as it is the most common case (lightningdevkit#2887). * `ClosureReason::CooperativeClosure` is now split into `{Counterparty,Locally}Initiated` variants (lightningdevkit#2863). * `Event::ChannelPending::channel_type` is now provided (lightningdevkit#2872). * `PaymentForwarded::{prev,next}_user_channel_id` are now provided (lightningdevkit#2924). * Channel init messages have been refactored towards V2 channels (lightningdevkit#2871). * `BumpTransactionEvent` now contains the channel and counterparty (lightningdevkit#2873). * `util::scid_utils` is now public, with some trivial utilities to examine short channel ids (lightningdevkit#2694). * `DirectedChannelInfo::{source,target}` are now public (lightningdevkit#2870). * Bounds in `lightning-background-processor` were simplified by using `AChannelManager` (lightningdevkit#2963). * The `Persist` impl for `KVStore` no longer requires `Sized`, allowing for the use of `dyn KVStore` as `Persist` (lightningdevkit#2883, lightningdevkit#2976). * `From<PaymentPreimage>` is now implemented for `PaymentHash` (lightningdevkit#2918). * `NodeId::from_slice` is now provided (lightningdevkit#2942). * `ChannelManager` deserialization may now fail with `DangerousValue` when LDK's persistence API was violated (lightningdevkit#2974). Bug Fixes ========= * Excess fees on counterparty commitment transactions are now included in the dust exposure calculation. This lines behavior up with some cases where transaction fees can be burnt, making them effectively dust exposure (lightningdevkit#3045). * `Future`s used as an `std::...::Future` could grow in size unbounded if it was never woken. For those not using async persistence and using the async `lightning-background-processor`, this could cause a memory leak in the `ChainMonitor` (lightningdevkit#2894). * Inbound channel requests that fail in `ChannelManager::accept_inbound_channel` would previously have stalled from the peer's perspective as no `error` message was sent (lightningdevkit#2953). * Blinded path construction has been tuned to select paths more likely to succeed, improving BOLT12 payment reliability (lightningdevkit#2911, lightningdevkit#2912). * After a reorg, `lightning-transaction-sync` could have failed to follow a transaction that LDK needed information about (lightningdevkit#2946). * `RecipientOnionFields`' `custom_tlvs` are now propagated to recipients when paying with blinded paths (lightningdevkit#2975). * `Event::ChannelClosed` is now properly generated and peers are properly notified for all channels that as a part of a batch channel open fail to be funded (lightningdevkit#3029). * In cases where user event processing is substantially delayed such that we complete multiple round-trips with our peers before a `PaymentSent` event is handled and then restart without persisting the `ChannelManager` after having persisted a `ChannelMonitor[Update]`, on startup we may have `Err`d trying to deserialize the `ChannelManager` (lightningdevkit#3021). * If a peer has relatively high latency, `PeerManager` may have failed to establish a connection (lightningdevkit#2993). * `ChannelUpdate` messages broadcasted for our own channel closures are now slightly more robust (lightningdevkit#2731). * Deserializing malformed BOLT11 invoices may have resulted in an integer overflow panic in debug builds (lightningdevkit#3032). * In exceedingly rare cases (no cases of this are known), LDK may have created an invalid serialization for a `ChannelManager` (lightningdevkit#2998). * Message processing latency handling BOLT12 payments has been reduced (lightningdevkit#2881). * Latency in processing `Event::SpendableOutputs` may be reduced (lightningdevkit#3033). Node Compatibility ================== * LDK's blinded paths were inconsistent with other implementations in several ways, which have been addressed (lightningdevkit#2856, lightningdevkit#2936, lightningdevkit#2945). * LDK's messaging blinded paths now support the latest features which some nodes may begin relying on soon (lightningdevkit#2961). * LDK's BOLT12 structs have been updated to support some last-minute changes to the spec (lightningdevkit#3017, lightningdevkit#3018). * CLN v24.02 requires the `gossip_queries` feature for all peers, however LDK by default does not set it for those not using a `P2PGossipSync` (e.g. those using RGS). This change was reverted in CLN v24.02.2 however for now LDK always sets the `gossip_queries` feature. This change is expected to be reverted in a future LDK release (lightningdevkit#2959). Security ======== 0.0.123 fixes a denial-of-service vulnerability which we believe to be reachable from untrusted input when parsing invalid BOLT11 invoices containing non-ASCII characters. * BOLT11 invoices with non-ASCII characters in the human-readable-part may cause an out-of-bounds read attempt leading to a panic (lightningdevkit#3054). Note that all BOLT11 invoices containing non-ASCII characters are invalid. In total, this release features 150 files changed, 19307 insertions, 6306 deletions in 360 commits since 0.0.121 from 17 authors, in alphabetical order: * Arik Sosman * Duncan Dean * Elias Rohrer * Evan Feenstra * Jeffrey Czyz * Keyue Bao * Matt Corallo * Orbital * Sergi Delgado Segura * Valentine Wallace * Willem Van Lint * Wilmer Paulino * benthecarman * jbesraa * olegkubrakov * optout * shaavan

tnull mentioned this pull request Apr 17, 2024

Hold PeerState in an RwLock rather than a Mutex #2968

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TheBlueMatt approved these changes Apr 18, 2024

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TheBlueMatt added this to the 0.0.123 milestone Apr 18, 2024

G8XSU reviewed Apr 18, 2024

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G8XSU approved these changes Apr 18, 2024

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G8XSU merged commit ae4c35c into lightningdevkit:main Apr 18, 2024
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Acquire `per_peer_state` `write` lock earlier in `ChannelManager::write` #2998

Acquire `per_peer_state` `write` lock earlier in `ChannelManager::write` #2998

tnull commented Apr 17, 2024

G8XSU Apr 18, 2024

tnull Apr 18, 2024

G8XSU Apr 18, 2024

Acquire per_peer_state write lock earlier in ChannelManager::write #2998

Acquire per_peer_state write lock earlier in ChannelManager::write #2998

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tnull commented Apr 17, 2024

G8XSU Apr 18, 2024

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tnull Apr 18, 2024

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G8XSU Apr 18, 2024

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Acquire `per_peer_state` `write` lock earlier in `ChannelManager::write` #2998

Acquire `per_peer_state` `write` lock earlier in `ChannelManager::write` #2998