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disabling: persist disabled state within one era #1966

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ordian opened this issue Oct 20, 2023 · 2 comments · Fixed by #2226
Closed

disabling: persist disabled state within one era #1966

ordian opened this issue Oct 20, 2023 · 2 comments · Fixed by #2226
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@tdimitrov

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@ordian
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ordian commented Oct 20, 2023

Currently, we clear out disabled validators in the session pallet on session boundaries. This makes attack on session boundaries easier while avoiding being disabled. We can even consider persisting disabled state to one next era if the validator is chosen again. Note: this might require tracking key rotations properly.
@ordian ordian moved this to Backlog in parachains team board Oct 20, 2023
@eskimor eskimor moved this from Backlog to In Progress in parachains team board Nov 8, 2023
@tdimitrov tdimitrov mentioned this issue Nov 8, 2023
Merged
@tdimitrov tdimitrov moved this from In Progress to Review in progress in parachains team board Nov 17, 2023
@Overkillus
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I agree that we want disabling to last 1 era but this is in fact already the case!

Technically from the perspective of a session pallet disabled validators are cleared when it ends. But the staking pallet that hosts the session pallet actually repopulates the disabled list on a new session start here. This should persist the disabled list for the whole era if I'm reading everything correctly.

This intention is also reflected in the original PR for an old issue staking: only disable slashed validators and keep them disabled for whole era. Explicitly the behaviour we wanted supposedly already implemented 😃

#2226 is not needed to enable this behaviour and we can close the issue.

@github-project-automation github-project-automation bot moved this from Review in progress to Completed in parachains team board Apr 10, 2024
github-merge-queue bot pushed a commit that referenced this issue Apr 26, 2024
@tdimitrov @ordian
@Overkillus @gpestana @kianenigma @Ank4n
Implementation of the new validator disabling strategy (#2226)
988e30f 
Closes #1966,
#1963 and
#1962.

Disabling strategy specification
[here](#2955). (Updated
13/02/2024)

Implements:
* validator disabling for a whole era instead of just a session
* no more than 1/3 of the validators in the active set are disabled
Removes:
* `DisableStrategy` enum - now each validator committing an offence is
disabled.
* New era is not forced if too many validators are disabled.

Before this PR not all offenders were disabled. A decision was made
based on [`enum
DisableStrategy`](https://github.com/paritytech/polkadot-sdk/blob/bbb6631641f9adba30c0ee6f4d11023a424dd362/substrate/primitives/staking/src/offence.rs#L54).
Some offenders were disabled for a whole era, some just for a session,
some were not disabled at all.

This PR changes the disabling behaviour. Now a validator committing an
offense is disabled immediately till the end of the current era.

Some implementation notes:
* `OffendingValidators` in pallet session keeps all offenders (this is
not changed). However its type is changed from `Vec<(u32, bool)>` to
`Vec<u32>`. The reason is simple - each offender is getting disabled so
the bool doesn't make sense anymore.
* When a validator is disabled it is first added to
`OffendingValidators` and then to `DisabledValidators`. This is done in
[`add_offending_validator`](https://github.com/paritytech/polkadot-sdk/blob/bbb6631641f9adba30c0ee6f4d11023a424dd362/substrate/frame/staking/src/slashing.rs#L325)
from staking pallet.
* In
[`rotate_session`](https://github.com/paritytech/polkadot-sdk/blob/bdbe98297032e21a553bf191c530690b1d591405/substrate/frame/session/src/lib.rs#L623)
the `end_session` also calls
[`end_era`](https://github.com/paritytech/polkadot-sdk/blob/bbb6631641f9adba30c0ee6f4d11023a424dd362/substrate/frame/staking/src/pallet/impls.rs#L490)
when an era ends. In this case `OffendingValidators` are cleared
**(1)**.
* Then in
[`rotate_session`](https://github.com/paritytech/polkadot-sdk/blob/bdbe98297032e21a553bf191c530690b1d591405/substrate/frame/session/src/lib.rs#L623)
`DisabledValidators` are cleared **(2)**
* And finally (still in `rotate_session`) a call to
[`start_session`](https://github.com/paritytech/polkadot-sdk/blob/bbb6631641f9adba30c0ee6f4d11023a424dd362/substrate/frame/staking/src/pallet/impls.rs#L430)
repopulates the disabled validators **(3)**.
* The reason for this complication is that session pallet knows nothing
abut eras. To overcome this on each new session the disabled list is
repopulated (points 2 and 3). Staking pallet knows when a new era starts
so with point 1 it ensures that the offenders list is cleared.

---------

Co-authored-by: ordian <[email protected]>
Co-authored-by: ordian <[email protected]>
Co-authored-by: Maciej <[email protected]>
Co-authored-by: Gonçalo Pestana <[email protected]>
Co-authored-by: Kian Paimani <[email protected]>
Co-authored-by: command-bot <>
Co-authored-by: Ankan <[email protected]>
Morganamilo pushed a commit that referenced this issue May 2, 2024
@tdimitrov @ordian
@Overkillus @gpestana @kianenigma @Ank4n @Morganamilo
Implementation of the new validator disabling strategy (#2226)
b7de450 
Closes #1966,
#1963 and
#1962.

Disabling strategy specification
[here](#2955). (Updated
13/02/2024)

Implements:
* validator disabling for a whole era instead of just a session
* no more than 1/3 of the validators in the active set are disabled
Removes:
* `DisableStrategy` enum - now each validator committing an offence is
disabled.
* New era is not forced if too many validators are disabled.

Before this PR not all offenders were disabled. A decision was made
based on [`enum
DisableStrategy`](https://github.com/paritytech/polkadot-sdk/blob/bbb6631641f9adba30c0ee6f4d11023a424dd362/substrate/primitives/staking/src/offence.rs#L54).
Some offenders were disabled for a whole era, some just for a session,
some were not disabled at all.

This PR changes the disabling behaviour. Now a validator committing an
offense is disabled immediately till the end of the current era.

Some implementation notes:
* `OffendingValidators` in pallet session keeps all offenders (this is
not changed). However its type is changed from `Vec<(u32, bool)>` to
`Vec<u32>`. The reason is simple - each offender is getting disabled so
the bool doesn't make sense anymore.
* When a validator is disabled it is first added to
`OffendingValidators` and then to `DisabledValidators`. This is done in
[`add_offending_validator`](https://github.com/paritytech/polkadot-sdk/blob/bbb6631641f9adba30c0ee6f4d11023a424dd362/substrate/frame/staking/src/slashing.rs#L325)
from staking pallet.
* In
[`rotate_session`](https://github.com/paritytech/polkadot-sdk/blob/bdbe98297032e21a553bf191c530690b1d591405/substrate/frame/session/src/lib.rs#L623)
the `end_session` also calls
[`end_era`](https://github.com/paritytech/polkadot-sdk/blob/bbb6631641f9adba30c0ee6f4d11023a424dd362/substrate/frame/staking/src/pallet/impls.rs#L490)
when an era ends. In this case `OffendingValidators` are cleared
**(1)**.
* Then in
[`rotate_session`](https://github.com/paritytech/polkadot-sdk/blob/bdbe98297032e21a553bf191c530690b1d591405/substrate/frame/session/src/lib.rs#L623)
`DisabledValidators` are cleared **(2)**
* And finally (still in `rotate_session`) a call to
[`start_session`](https://github.com/paritytech/polkadot-sdk/blob/bbb6631641f9adba30c0ee6f4d11023a424dd362/substrate/frame/staking/src/pallet/impls.rs#L430)
repopulates the disabled validators **(3)**.
* The reason for this complication is that session pallet knows nothing
abut eras. To overcome this on each new session the disabled list is
repopulated (points 2 and 3). Staking pallet knows when a new era starts
so with point 1 it ensures that the offenders list is cleared.

---------

Co-authored-by: ordian <[email protected]>
Co-authored-by: ordian <[email protected]>
Co-authored-by: Maciej <[email protected]>
Co-authored-by: Gonçalo Pestana <[email protected]>
Co-authored-by: Kian Paimani <[email protected]>
Co-authored-by: command-bot <>
Co-authored-by: Ankan <[email protected]>
@Overkillus
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For clarity. This behaviour was already present even before #2226 got merged. Disabling was lasting for a full era with when the staking pallet is present. A false assumption was made that disabling lasted for a session (4h) instead of an era (24h) because the session pallet clears the disabled validators list every session. When the staking pallet is present it repopulates the session's disabled validator list until the era changes effectively making them last for a full era.

TarekkMA pushed a commit to moonbeam-foundation/polkadot-sdk that referenced this issue Aug 2, 2024
@tdimitrov @ordian
@Overkillus @gpestana @kianenigma @Ank4n @TarekkMA
Implementation of the new validator disabling strategy (paritytech#2226)
34660a6 
Closes paritytech#1966,
paritytech#1963 and
paritytech#1962.

Disabling strategy specification
[here](paritytech#2955). (Updated
13/02/2024)

Implements:
* validator disabling for a whole era instead of just a session
* no more than 1/3 of the validators in the active set are disabled
Removes:
* `DisableStrategy` enum - now each validator committing an offence is
disabled.
* New era is not forced if too many validators are disabled.

Before this PR not all offenders were disabled. A decision was made
based on [`enum
DisableStrategy`](https://github.com/paritytech/polkadot-sdk/blob/bbb6631641f9adba30c0ee6f4d11023a424dd362/substrate/primitives/staking/src/offence.rs#L54).
Some offenders were disabled for a whole era, some just for a session,
some were not disabled at all.

This PR changes the disabling behaviour. Now a validator committing an
offense is disabled immediately till the end of the current era.

Some implementation notes:
* `OffendingValidators` in pallet session keeps all offenders (this is
not changed). However its type is changed from `Vec<(u32, bool)>` to
`Vec<u32>`. The reason is simple - each offender is getting disabled so
the bool doesn't make sense anymore.
* When a validator is disabled it is first added to
`OffendingValidators` and then to `DisabledValidators`. This is done in
[`add_offending_validator`](https://github.com/paritytech/polkadot-sdk/blob/bbb6631641f9adba30c0ee6f4d11023a424dd362/substrate/frame/staking/src/slashing.rs#L325)
from staking pallet.
* In
[`rotate_session`](https://github.com/paritytech/polkadot-sdk/blob/bdbe98297032e21a553bf191c530690b1d591405/substrate/frame/session/src/lib.rs#L623)
the `end_session` also calls
[`end_era`](https://github.com/paritytech/polkadot-sdk/blob/bbb6631641f9adba30c0ee6f4d11023a424dd362/substrate/frame/staking/src/pallet/impls.rs#L490)
when an era ends. In this case `OffendingValidators` are cleared
**(1)**.
* Then in
[`rotate_session`](https://github.com/paritytech/polkadot-sdk/blob/bdbe98297032e21a553bf191c530690b1d591405/substrate/frame/session/src/lib.rs#L623)
`DisabledValidators` are cleared **(2)**
* And finally (still in `rotate_session`) a call to
[`start_session`](https://github.com/paritytech/polkadot-sdk/blob/bbb6631641f9adba30c0ee6f4d11023a424dd362/substrate/frame/staking/src/pallet/impls.rs#L430)
repopulates the disabled validators **(3)**.
* The reason for this complication is that session pallet knows nothing
abut eras. To overcome this on each new session the disabled list is
repopulated (points 2 and 3). Staking pallet knows when a new era starts
so with point 1 it ensures that the offenders list is cleared.

---------

Co-authored-by: ordian <[email protected]>
Co-authored-by: ordian <[email protected]>
Co-authored-by: Maciej <[email protected]>
Co-authored-by: Gonçalo Pestana <[email protected]>
Co-authored-by: Kian Paimani <[email protected]>
Co-authored-by: command-bot <>
Co-authored-by: Ankan <[email protected]>
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Implementation of the new validator disabling strategy paritytech/polkadot-sdk
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@tdimitrov @ordian @Overkillus