fuel_vm/predicate.rs
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//! Predicate representations with required data to be executed during VM runtime
use fuel_tx::field;
use crate::interpreter::MemoryRange;
/// Runtime representation of a predicate
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub struct RuntimePredicate {
range: MemoryRange,
idx: usize,
}
impl RuntimePredicate {
/// Empty predicate for testing
#[cfg(test)]
pub const fn empty() -> Self {
Self {
range: MemoryRange::new(0, 0),
idx: 0,
}
}
/// Memory slice with the program representation of the predicate
pub const fn program(&self) -> &MemoryRange {
&self.range
}
/// Index of the transaction input that maps to this predicate
pub const fn idx(&self) -> usize {
self.idx
}
/// Create a new runtime predicate from a transaction, given the input index
///
/// Return `None` if the tx input doesn't map to an input with a predicate
pub fn from_tx<T>(tx: &T, tx_offset: usize, idx: usize) -> Option<Self>
where
T: field::Inputs,
{
let (ofs, len) = tx.inputs_predicate_offset_at(idx)?;
let addr = ofs.saturating_add(tx_offset);
Some(Self {
range: MemoryRange::new(addr, len),
idx,
})
}
}
#[allow(clippy::cast_possible_truncation)]
#[cfg(test)]
mod tests {
use alloc::{
vec,
vec::Vec,
};
use core::iter;
use fuel_asm::op;
use fuel_tx::{
field::ScriptGasLimit,
TransactionBuilder,
};
use fuel_types::bytes;
use rand::{
rngs::StdRng,
Rng,
SeedableRng,
};
use crate::{
checked_transaction::{
CheckPredicateParams,
EstimatePredicates,
},
constraints::reg_key::{
HP,
IS,
ONE,
SSP,
ZERO,
},
error::PredicateVerificationFailed,
interpreter::InterpreterParams,
prelude::{
predicates::check_predicates,
*,
},
storage::{
predicate::empty_predicate_storage,
BlobData,
},
};
#[test]
fn from_tx_works() {
let rng = &mut StdRng::seed_from_u64(2322u64);
let height = 1.into();
#[rustfmt::skip]
let predicate: Vec<u8> = vec![
op::addi(0x10, 0x00, 0x01),
op::addi(0x10, 0x10, 0x01),
op::ret(0x01),
].into_iter().collect();
let predicate_data = b"If people do not believe that mathematics is simple, it is only because they do not realize how complicated life is.".to_vec();
let owner = (*Contract::root_from_code(&predicate)).into();
let a = Input::coin_predicate(
rng.gen(),
owner,
rng.gen(),
rng.gen(),
rng.gen(),
0,
predicate.clone(),
predicate_data.clone(),
);
let b = Input::message_coin_predicate(
rng.gen(),
rng.gen(),
rng.gen(),
rng.gen(),
0,
predicate.clone(),
predicate_data.clone(),
);
let c = Input::message_data_predicate(
rng.gen(),
rng.gen(),
rng.gen(),
rng.gen(),
0,
vec![0xff; 10],
predicate.clone(),
predicate_data,
);
let inputs = vec![a, b, c];
for i in inputs {
let tx = TransactionBuilder::script(vec![], vec![])
.add_input(i)
.add_fee_input()
.finalize_checked_basic(height);
// assert invalid idx wont panic
let idx = 1;
let tx_offset = TxParameters::DEFAULT.tx_offset();
let runtime = RuntimePredicate::from_tx(tx.as_ref(), tx_offset, idx);
assert!(runtime.is_none());
// fetch the input predicate
let idx = 0;
let runtime = RuntimePredicate::from_tx(tx.as_ref(), tx_offset, idx)
.expect("failed to generate predicate from valid tx");
assert_eq!(idx, runtime.idx());
let mut interpreter = Interpreter::<_, _, _>::with_storage(
MemoryInstance::new(),
empty_predicate_storage(),
InterpreterParams::default(),
);
assert!(interpreter
.init_predicate(
Context::PredicateVerification {
program: RuntimePredicate::empty(),
},
tx.transaction().clone(),
*tx.transaction().script_gas_limit(),
)
.is_ok());
let pad = bytes::padded_len(&predicate).unwrap() - predicate.len();
// assert we are testing an edge case
assert_ne!(0, pad);
let padded_predicate: Vec<u8> = predicate
.iter()
.copied()
.chain(iter::repeat(0u8).take(pad))
.collect();
let program = runtime.program();
let program = &interpreter.memory()[program.usizes()];
// assert the program in the vm memory is the same of the input
assert_eq!(program, &padded_predicate);
}
}
fn assert_inputs_are_validated_for_predicates(
inputs: Vec<(
Vec<Instruction>,
bool,
Result<(), PredicateVerificationFailed>,
)>,
blob: Vec<Instruction>,
) {
let rng = &mut StdRng::seed_from_u64(2322u64);
let height = 1.into();
let predicate_data =
b"If you think it's simple, then you have misunderstood the problem."
.to_vec();
let mut storage = MemoryStorage::new(Default::default(), Default::default());
let blob_id = BlobId::zeroed();
let blob: Vec<u8> = blob.into_iter().collect();
storage
.storage_as_mut::<BlobData>()
.insert(&blob_id, &blob)
.unwrap();
macro_rules! predicate_input {
($predicate:expr) => {{
let predicate: Vec<u8> = $predicate.into_iter().collect();
let owner = Input::predicate_owner(&predicate);
[
Input::coin_predicate(
rng.gen(),
owner,
rng.gen(),
rng.gen(),
rng.gen(),
0,
predicate.clone(),
predicate_data.clone(),
),
Input::message_coin_predicate(
rng.gen(),
owner,
rng.gen(),
rng.gen(),
0,
predicate.clone(),
predicate_data.clone(),
),
Input::message_data_predicate(
rng.gen(),
owner,
rng.gen(),
rng.gen(),
0,
vec![rng.gen(); rng.gen_range(1..100)],
predicate.clone(),
predicate_data.clone(),
),
]
}};
}
for (i, (input_predicate, correct_gas, expected)) in
inputs.into_iter().enumerate()
{
let input_group = predicate_input!(input_predicate);
for mut input in input_group {
if !correct_gas {
input.set_predicate_gas_used(1234);
}
let mut script = TransactionBuilder::script(
[op::ret(0x01)].into_iter().collect(),
vec![],
)
.add_input(input)
.add_fee_input()
.finalize();
if correct_gas {
script
.estimate_predicates(
&CheckPredicateParams::default(),
MemoryInstance::new(),
&storage,
)
.unwrap();
}
let tx = script
.into_checked_basic(height, &Default::default())
.unwrap();
let result = check_predicates(
&tx,
&CheckPredicateParams::default(),
MemoryInstance::new(),
&storage,
);
assert_eq!(result.map(|_| ()), expected, "failed at input {}", i);
}
}
}
/// Verifies the runtime predicate validation rules outlined in the spec are actually
/// validated https://github.com/FuelLabs/fuel-specs/blob/master/src/fuel-vm/index.md#predicate-verification
#[test]
fn inputs_are_validated_for_good_predicate_inputs() {
const CORRECT_GAS: bool = true;
let good_blob = vec![op::noop(), op::ret(0x01)];
let inputs = vec![
(
// A valid predicate
vec![
op::addi(0x10, 0x00, 0x01),
op::addi(0x10, 0x10, 0x01),
op::ret(0x01),
],
CORRECT_GAS,
Ok(()),
),
(
// Use `LDC` with mode `1` to load the blob into the predicate.
vec![
// Allocate 32 byte on the heap.
op::movi(0x10, 32),
op::aloc(0x10),
// This will be our zeroed blob id
op::move_(0x10, HP),
// Store the size of the blob
op::bsiz(0x11, 0x10),
// Store start of the blob code
op::move_(0x12, SSP),
// Subtract the start of the code from the end of the code
op::sub(0x12, 0x12, IS),
// Divide the code by the instruction size to get the number of
// instructions
op::divi(0x12, 0x12, Instruction::SIZE as u16),
// Load the blob by `0x10` ID with the `0x11` size
op::ldc(0x10, ZERO, 0x11, 1),
// Jump to a new code location
op::jmp(0x12),
],
CORRECT_GAS,
Ok(()),
),
(
// Use `LDC` with mode `2` to load the part of the predicate from the
// transaction.
vec![
// Skip the return opcodes. One of two opcodes is a good opcode that
// returns `0x1`. This opcode is our source for the `LDC`
// opcode. We will copy return good opcode to the end
// of the `ssp` via `LDC`. And jump there to
// return `true` from the predicate.
op::jmpf(ZERO, 2),
// Bad return opcode that we want to skip.
op::ret(0x0),
// Good return opcode that we want to use for the `LDC`.
op::ret(0x1),
// Take the start of the code and move it for 2 opcodes to get the
// desired opcode to copy.
op::move_(0x10, IS),
// We don't need to copy `jmpf` and bad `ret` opcodes via `LDC`.
op::addi(0x10, 0x10, 2 * Instruction::SIZE as u16),
// Store end of the code
op::move_(0x12, SSP),
// Subtract the start of the code from the end of the code
op::sub(0x12, 0x12, IS),
// Divide the code by the instruction size to get the number of
// instructions
op::divi(0x12, 0x12, Instruction::SIZE as u16),
// We want to load only on good `ret` opcode.
op::movi(0x11, Instruction::SIZE as u32),
// Load the code from the memory address `0x10` with the `0x11` size
op::ldc(0x10, ZERO, 0x11, 2),
// Jump to a new code location
op::jmp(0x12),
],
CORRECT_GAS,
Ok(()),
),
];
assert_inputs_are_validated_for_predicates(inputs, good_blob)
}
#[test]
fn inputs_are_validated_for_bad_predicate_inputs() {
const CORRECT_GAS: bool = true;
const INCORRECT_GAS: bool = false;
let bad_blob = vec![op::noop(), op::ret(0x00)];
let inputs = vec![
(
// A valid predicate, but gas amount mismatches
vec![
op::addi(0x10, 0x00, 0x01),
op::addi(0x10, 0x10, 0x01),
op::ret(0x01),
],
INCORRECT_GAS,
Err(PredicateVerificationFailed::GasMismatch),
),
(
// Returning an invalid value
vec![op::ret(0x0)],
CORRECT_GAS,
Err(PredicateVerificationFailed::Panic(
PanicReason::PredicateReturnedNonOne,
)),
),
(
// Using a contract instruction
vec![op::time(0x20, 0x1), op::ret(0x1)],
CORRECT_GAS,
Err(PredicateVerificationFailed::PanicInstruction(
PanicInstruction::error(
PanicReason::ContractInstructionNotAllowed,
op::time(0x20, 0x1).into(),
),
)),
),
(
// Using a contract instruction
vec![op::ldc(ONE, ONE, ONE, 0)],
CORRECT_GAS,
Err(PredicateVerificationFailed::PanicInstruction(
PanicInstruction::error(
PanicReason::ContractInstructionNotAllowed,
op::ldc(ONE, ONE, ONE, 0).into(),
),
)),
),
(
// Use `LDC` with mode `1` to load the blob into the predicate.
vec![
// Allocate 32 byte on the heap.
op::movi(0x10, 32),
op::aloc(0x10),
// This will be our zeroed blob id
op::move_(0x10, HP),
// Store the size of the blob
op::bsiz(0x11, 0x10),
// Store start of the blob code
op::move_(0x12, SSP),
// Subtract the start of the code from the end of the code
op::sub(0x12, 0x12, IS),
// Divide the code by the instruction size to get the number of
// instructions
op::divi(0x12, 0x12, Instruction::SIZE as u16),
// Load the blob by `0x10` ID with the `0x11` size
op::ldc(0x10, ZERO, 0x11, 1),
// Jump to a new code location
op::jmp(0x12),
],
CORRECT_GAS,
Err(PredicateVerificationFailed::Panic(
PanicReason::PredicateReturnedNonOne,
)),
),
(
// Use `LDC` with mode `2` to load the part of the predicate from the
// transaction.
vec![
// Skip the return opcodes. One of two opcodes is a bad opcode that
// returns `0x0`. This opcode is our source for the `LDC`
// opcode. We will copy return bad opcode to the end
// of the `ssp` via `LDC`. And jump there to
// return `false` from the predicate adn fail.
op::jmpf(ZERO, 2),
// Good return opcode that we want to skip.
op::ret(0x1),
// Bad return opcode that we want to use for the `LDC`.
op::ret(0x0),
// Take the start of the code and move it for 2 opcodes to get the
// desired opcode to copy.
op::move_(0x10, IS),
// We don't need to copy `jmpf` and bad `ret` opcodes via `LDC`.
op::addi(0x10, 0x10, 2 * Instruction::SIZE as u16),
// Store end of the code
op::move_(0x12, SSP),
// Subtract the start of the code from the end of the code
op::sub(0x12, 0x12, IS),
// Divide the code by the instruction size to get the number of
// instructions
op::divi(0x12, 0x12, Instruction::SIZE as u16),
// We want to load only on bad `ret` opcode.
op::movi(0x11, Instruction::SIZE as u32),
// Load the code from the memory address `0x10` with the `0x11` size
op::ldc(0x10, ZERO, 0x11, 2),
// Jump to a new code location
op::jmp(0x12),
],
CORRECT_GAS,
Err(PredicateVerificationFailed::Panic(
PanicReason::PredicateReturnedNonOne,
)),
),
];
assert_inputs_are_validated_for_predicates(inputs, bad_blob)
}
}