Allowlists & Sentinels¶

ComposablePolicy ships with two hard-coded program allowlists and a pair of sentinel conventions that let a policy disable either hook without special-cased branches throughout the codebase. This page documents both and the create-time / execute-time checks that enforce them.

Allowlists¶

Defined in programs/tributary/src/constants.rs:

pub const ALLOWED_FORWARD_PROGRAMS: &[Pubkey] =
    &[pubkey!("LBUZKhRxPF3XUpBCjp4YzTKgLccjZhTSDM9YuVaPwxo")]; // Meteora DLMM

pub const ALLOWED_VALIDATION_PROGRAMS: &[Pubkey] =
    &[pubkey!("L2TExMFKdjpN9kozasaurPirfHy9P8sbXoAN1qA3S95")]; // Lighthouse

Constant	Currently contains	Used by
`ALLOWED_FORWARD_PROGRAMS`	Meteora DLMM (1 entry)	`validate_forward_config`, execute handler
`ALLOWED_VALIDATION_PROGRAMS`	Lighthouse (1 entry)	`create_composable_policy`

Allowlisting exists because both hooks receive invoke_signed-style authority over the ComposablePolicy PDA's intermediate ATAs. An arbitrary program in either slot could move transient balances to attacker accounts. Hard-allowlisting caps the blast radius to two well-audited programs whose instruction semantics Tributary understands (and, in the forward case, pins via ByteRangeCheck discriminator checks — see forward-hook.md).

Sentinel conventions¶

Hook	Disabled when…	Sentinel
Forward	`instruction_constraint.program_id == Pubkey::default()`	`Pubkey::default()`
Validation	`ValidationSpec::Disabled`	enum variant

The two hooks use different sentinel conventions. Forward uses a pubkey sentinel (Pubkey::default() on instruction_constraint.program_id) since program ID is the single gate. Validation uses an enum variant (ValidationSpec::Disabled) because the spec carries no pubkey — when disabled no assertion data is stored, no ValidationPda is allocated, and the caller passes SystemProgram as the program account.

Forward-disabled invariants¶

When instruction_constraint.program_id == Pubkey::default():

ic.num_data_checks == 0 (no forward instruction selector to pin).
output_mint == input_mint (no conversion step — the "same-mint topup" pattern. The intermediate is funded by the pull and swept directly).
Execute handler skips both the byte-range check and run_forward_cpi.

Validation-disabled invariants¶

When the spec is ValidationSpec::Disabled:

validation_data.is_empty() (no assertion to store — enforced by validate_init at create time).
No ValidationPda account is allocated (neither pre nor post).
Execute handler skips Phase 2 (pre-validation) and Phase 4 (post-validation) entirely; it consumes zero remaining_accounts for validation, and the caller passes SystemProgram as the program account.

Create-time checks¶

Forward config (`validate_forward_config`)¶

The forward-leg rules are extracted into a unit-testable helper. The current function reads num_data_checks and program_id through the nested instruction_constraint:

pub fn validate_forward_config(forward_config: &ForwardConfig) -> Result<()> {
    let ic = &forward_config.instruction_constraint;
    let forward_disabled = ic.is_disabled();

    require!(
        forward_disabled || ALLOWED_FORWARD_PROGRAMS.contains(&ic.program_id),
        TributaryError::InvalidForwardProgram
    );

    if forward_disabled {
        require!(ic.num_data_checks == 0,
                 TributaryError::InsufficientByteRangeChecks);
        require!(forward_config.output_mint == forward_config.input_mint,
                 TributaryError::ForwardDisabledRequiresSameMint);
    } else {
        require!(ic.num_data_checks >= 1
                 && ic.num_data_checks <= MAX_BYTE_RANGE_CHECKS as u8,
                 TributaryError::InsufficientByteRangeChecks);
        require!(ic.has_effective_pins(),
                 TributaryError::DegenerateForwardPins);
        require!(!ic.has_duplicate_indices(),
                 TributaryError::DuplicatePinIndex);
    }

    if forward_config.is_native_output() {
        require!(forward_config.output_mint == NATIVE_MINT,
                 TributaryError::NativeOutputRequiresWsol);
    }
    Ok(())
}

The per-ByteRangeCheck sanity loop (including the discriminator-pin requirement for offset 0) lives in the handler body itself, iterating forward_config.instruction_constraint.data_checks[i] — see create_composable_policy.rs.

Validation specs (`validate_spec_and_program` + `validate_init`)¶

Validation is now handled per-slot (pre and post) through the ValidationSpec enum. At create time the handler calls:

// Resolve each spec against the caller-supplied program account.
validate_spec_and_program(pre_validation,
    ctx.accounts.pre_validation_program.key(),
    ctx.accounts.system_program.key())?;
validate_spec_and_program(post_validation,
    ctx.accounts.post_validation_program.key(),
    ctx.accounts.system_program.key())?;

// Then validate the init data for each (assertion bytes, pin set).
validate_init(&pre_validation, &pre_init)?;
validate_init(&post_validation, &post_init)?;

Where validate_spec_and_program dispatches on the enum:

ValidationSpec::Disabled → the passed program account must be SystemProgram (no CPI target needed). No ValidationPda is allocated.
ValidationSpec::ProgramCall { program_id } → the passed program must match program_id, which must be in ALLOWED_VALIDATION_PROGRAMS.
ValidationSpec::Inline { .. } → returns InlineValidationNotImplemented.

And validate_init ensures:

When Disabled: validation_data must be empty (no assertion to store).
When ProgramCall: validation_data must be non-empty and ≤ 1024 bytes, pins must be non-default, indices unique, within bounds.

The handler also re-pins the named input_mint / output_mint accounts against the caller-supplied forward_config Pubkeys and runs the full Token-2022 extension allowlist on both (validate_mint_compatible). Without this, a policy could be created against a TransferHook / PermanentDelegate / ConfidentialTransferMint mint that breaks transfer_checked at execute time, or drains the PDA-owned intermediate ATA in the PermanentDelegate case (see reports/L-02-mint-validation-call-sites-incomplete.md).

Execute-time re-validation¶

The execute handler re-checks several invariants that were already enforced at create time. The pattern is defense-in-depth: these values are sourced from on-chain state, so a directly-serialized malformed account (or a regression in create-time validation) must not be able to trigger a panic or privilege escalation.

Re-check	Source report
`validate_mint_compatible(input_mint)` AND `(output_mint)` (Token-2022 extensions mutate)	L-02
`n <= checks.len()` before indexing `data_checks[i]`	H-04
`ByteRangeCheck::validate` rejects `length > 8` rather than panicking	H-06
`pre_validation.program_id() == pre_program_info.key()` (+ same for post)	C-1
`forward_config.target_program` allowlist (transitively, via stored state)	—

Emergency pause¶

ProgramConfig.emergency_pause is a global kill switch. The execute handler's config account carries:

#[account(
    seeds = [CONFIG_SEED],
    bump = config.bump,
    constraint = !config.emergency_pause,
)]
pub config: Box<Account<'info, ProgramConfig>>,

When the pause flag is true, every execute_composable (and execute_payment) call fails the constraint at the top of the handler, before any state is read or any CPI is attempted. Create is also blocked via the same flag on CreateComposablePolicy::config.

The flag is intended for incident response — e.g. an unresolved vulability in an allowlisted forward program. It does not freeze existing policy state; recipients and users retain full custody, and the flag can be cleared to resume execution.