solidity/libsolidity/formal/SymbolicState.cpp
2021-12-16 17:35:58 +01:00

338 lines
11 KiB
C++

/*
This file is part of solidity.
solidity is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
solidity is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with solidity. If not, see <http://www.gnu.org/licenses/>.
*/
// SPDX-License-Identifier: GPL-3.0
#include <libsolidity/formal/SymbolicState.h>
#include <libsolidity/formal/SymbolicTypes.h>
#include <libsolidity/formal/EncodingContext.h>
#include <libsolidity/formal/SMTEncoder.h>
using namespace std;
using namespace solidity;
using namespace solidity::smtutil;
using namespace solidity::frontend::smt;
BlockchainVariable::BlockchainVariable(
string _name,
map<string, smtutil::SortPointer> _members,
EncodingContext& _context
):
m_name(move(_name)),
m_members(move(_members)),
m_context(_context)
{
vector<string> members;
vector<SortPointer> sorts;
for (auto const& [component, sort]: m_members)
{
members.emplace_back(component);
sorts.emplace_back(sort);
m_componentIndices[component] = static_cast<unsigned>(members.size() - 1);
}
m_tuple = make_unique<SymbolicTupleVariable>(
make_shared<smtutil::TupleSort>(m_name + "_type", members, sorts),
m_name,
m_context
);
}
smtutil::Expression BlockchainVariable::member(string const& _member) const
{
return m_tuple->component(m_componentIndices.at(_member));
}
smtutil::Expression BlockchainVariable::assignMember(string const& _member, smtutil::Expression const& _value)
{
vector<smtutil::Expression> args;
for (auto const& m: m_members)
if (m.first == _member)
args.emplace_back(_value);
else
args.emplace_back(member(m.first));
m_tuple->increaseIndex();
auto tuple = m_tuple->currentValue();
auto sortExpr = smtutil::Expression(make_shared<smtutil::SortSort>(tuple.sort), tuple.name);
m_context.addAssertion(tuple == smtutil::Expression::tuple_constructor(sortExpr, args));
return m_tuple->currentValue();
}
void SymbolicState::reset()
{
m_error.resetIndex();
m_thisAddress.resetIndex();
m_state.reset();
m_tx.reset();
m_crypto.reset();
if (m_abi)
m_abi->reset();
}
smtutil::Expression SymbolicState::balances() const
{
return m_state.member("balances");
}
smtutil::Expression SymbolicState::balance() const
{
return balance(thisAddress());
}
smtutil::Expression SymbolicState::balance(smtutil::Expression _address) const
{
return smtutil::Expression::select(balances(), move(_address));
}
smtutil::Expression SymbolicState::blockhash(smtutil::Expression _blockNumber) const
{
return smtutil::Expression::select(m_tx.member("blockhash"), move(_blockNumber));
}
void SymbolicState::newBalances()
{
auto tupleSort = dynamic_pointer_cast<TupleSort>(stateSort());
auto balanceSort = tupleSort->components.at(tupleSort->memberToIndex.at("balances"));
SymbolicVariable newBalances(balanceSort, "fresh_balances_" + to_string(m_context.newUniqueId()), m_context);
m_state.assignMember("balances", newBalances.currentValue());
}
void SymbolicState::transfer(smtutil::Expression _from, smtutil::Expression _to, smtutil::Expression _value)
{
unsigned indexBefore = m_state.index();
addBalance(_from, 0 - _value);
addBalance(_to, move(_value));
unsigned indexAfter = m_state.index();
solAssert(indexAfter > indexBefore, "");
m_state.newVar();
/// Do not apply the transfer operation if _from == _to.
auto newState = smtutil::Expression::ite(
move(_from) == move(_to),
m_state.value(indexBefore),
m_state.value(indexAfter)
);
m_context.addAssertion(m_state.value() == newState);
}
void SymbolicState::addBalance(smtutil::Expression _address, smtutil::Expression _value)
{
auto newBalances = smtutil::Expression::store(
balances(),
_address,
balance(_address) + move(_value)
);
m_state.assignMember("balances", newBalances);
}
smtutil::Expression SymbolicState::txMember(string const& _member) const
{
return m_tx.member(_member);
}
smtutil::Expression SymbolicState::txTypeConstraints() const
{
return
smt::symbolicUnknownConstraints(m_tx.member("block.basefee"), TypeProvider::uint256()) &&
smt::symbolicUnknownConstraints(m_tx.member("block.chainid"), TypeProvider::uint256()) &&
smt::symbolicUnknownConstraints(m_tx.member("block.coinbase"), TypeProvider::address()) &&
smt::symbolicUnknownConstraints(m_tx.member("block.difficulty"), TypeProvider::uint256()) &&
smt::symbolicUnknownConstraints(m_tx.member("block.gaslimit"), TypeProvider::uint256()) &&
smt::symbolicUnknownConstraints(m_tx.member("block.number"), TypeProvider::uint256()) &&
smt::symbolicUnknownConstraints(m_tx.member("block.timestamp"), TypeProvider::uint256()) &&
smt::symbolicUnknownConstraints(m_tx.member("msg.sender"), TypeProvider::address()) &&
smt::symbolicUnknownConstraints(m_tx.member("msg.value"), TypeProvider::uint256()) &&
smt::symbolicUnknownConstraints(m_tx.member("tx.origin"), TypeProvider::address()) &&
smt::symbolicUnknownConstraints(m_tx.member("tx.gasprice"), TypeProvider::uint256());
}
smtutil::Expression SymbolicState::txNonPayableConstraint() const
{
return m_tx.member("msg.value") == 0;
}
smtutil::Expression SymbolicState::txFunctionConstraints(FunctionDefinition const& _function) const
{
smtutil::Expression conj = _function.isPayable() ? smtutil::Expression(true) : txNonPayableConstraint();
if (_function.isPartOfExternalInterface())
{
auto sig = TypeProvider::function(_function)->externalIdentifier();
conj = conj && m_tx.member("msg.sig") == sig;
auto b0 = sig >> (3 * 8);
auto b1 = (sig & 0x00ff0000) >> (2 * 8);
auto b2 = (sig & 0x0000ff00) >> (1 * 8);
auto b3 = (sig & 0x000000ff);
auto data = smtutil::Expression::tuple_get(m_tx.member("msg.data"), 0);
conj = conj && smtutil::Expression::select(data, 0) == b0;
conj = conj && smtutil::Expression::select(data, 1) == b1;
conj = conj && smtutil::Expression::select(data, 2) == b2;
conj = conj && smtutil::Expression::select(data, 3) == b3;
auto length = smtutil::Expression::tuple_get(m_tx.member("msg.data"), 1);
// TODO add ABI size of function input parameters here \/
conj = conj && length >= 4;
}
return conj;
}
void SymbolicState::prepareForSourceUnit(SourceUnit const& _source)
{
set<FunctionCall const*> abiCalls = SMTEncoder::collectABICalls(&_source);
for (auto const& source: _source.referencedSourceUnits(true))
abiCalls += SMTEncoder::collectABICalls(source);
buildABIFunctions(abiCalls);
}
/// Private helpers.
void SymbolicState::buildABIFunctions(set<FunctionCall const*> const& _abiFunctions)
{
map<string, SortPointer> functions;
for (auto const* funCall: _abiFunctions)
{
auto t = dynamic_cast<FunctionType const*>(funCall->expression().annotation().type);
auto const& args = funCall->sortedArguments();
auto const& paramTypes = t->parameterTypes();
auto const& returnTypes = t->returnParameterTypes();
auto argTypes = [](auto const& _args) {
return applyMap(_args, [](auto arg) { return arg->annotation().type; });
};
/// Since each abi.* function may have a different number of input/output parameters,
/// we generically compute those types.
vector<frontend::Type const*> inTypes;
vector<frontend::Type const*> outTypes;
if (t->kind() == FunctionType::Kind::ABIDecode)
{
/// abi.decode : (bytes, tuple_of_types(return_types)) -> (return_types)
solAssert(args.size() == 2, "Unexpected number of arguments for abi.decode");
inTypes.emplace_back(TypeProvider::bytesMemory());
auto argType = args.at(1)->annotation().type;
if (auto const* tupleType = dynamic_cast<TupleType const*>(argType))
for (auto componentType: tupleType->components())
{
auto typeType = dynamic_cast<TypeType const*>(componentType);
solAssert(typeType, "");
outTypes.emplace_back(typeType->actualType());
}
else if (auto const* typeType = dynamic_cast<TypeType const*>(argType))
outTypes.emplace_back(typeType->actualType());
else
solAssert(false, "Unexpected argument of abi.decode");
}
else if (t->kind() == FunctionType::Kind::ABIEncodeCall)
{
// abi.encodeCall : (functionPointer, tuple_of_args_or_one_non_tuple_arg(arguments)) -> bytes
solAssert(args.size() == 2, "Unexpected number of arguments for abi.encodeCall");
outTypes.emplace_back(TypeProvider::bytesMemory());
inTypes.emplace_back(args.at(0)->annotation().type);
inTypes.emplace_back(args.at(1)->annotation().type);
}
else
{
outTypes = returnTypes;
if (
t->kind() == FunctionType::Kind::ABIEncodeWithSelector ||
t->kind() == FunctionType::Kind::ABIEncodeWithSignature
)
{
/// abi.encodeWithSelector : (bytes4, one_or_more_types) -> bytes
/// abi.encodeWithSignature : (string, one_or_more_types) -> bytes
inTypes.emplace_back(paramTypes.front());
inTypes += argTypes(vector<ASTPointer<Expression const>>(args.begin() + 1, args.end()));
}
else
{
/// abi.encode/abi.encodePacked : one_or_more_types -> bytes
solAssert(
t->kind() == FunctionType::Kind::ABIEncode ||
t->kind() == FunctionType::Kind::ABIEncodePacked,
""
);
inTypes = argTypes(args);
}
}
/// Rational numbers and string literals add the concrete values to the type name,
/// so we replace them by uint256 and bytes since those are the same as their SMT types.
/// TODO we could also replace all types by their ABI type.
auto replaceTypes = [](auto& _types) {
for (auto& t: _types)
if (t->category() == frontend::Type::Category::RationalNumber)
t = TypeProvider::uint256();
else if (t->category() == frontend::Type::Category::StringLiteral)
t = TypeProvider::bytesMemory();
else if (auto userType = dynamic_cast<UserDefinedValueType const*>(t))
t = &userType->underlyingType();
};
replaceTypes(inTypes);
replaceTypes(outTypes);
auto name = t->richIdentifier();
for (auto paramType: inTypes + outTypes)
name += "_" + paramType->richIdentifier();
m_abiMembers[funCall] = {name, inTypes, outTypes};
if (functions.count(name))
continue;
/// If there is only one input or output parameter, we use that type directly.
/// Otherwise we create a tuple wrapping the necessary input or output types.
auto typesToSort = [](auto const& _types, string const& _name) -> shared_ptr<Sort> {
if (_types.size() == 1)
return smtSortAbstractFunction(*_types.front());
vector<string> inNames;
vector<SortPointer> sorts;
for (unsigned i = 0; i < _types.size(); ++i)
{
inNames.emplace_back(_name + "_input_" + to_string(i));
sorts.emplace_back(smtSortAbstractFunction(*_types.at(i)));
}
return make_shared<smtutil::TupleSort>(
_name + "_input",
inNames,
sorts
);
};
auto functionSort = make_shared<smtutil::ArraySort>(
typesToSort(inTypes, name),
typesToSort(outTypes, name)
);
functions[name] = functionSort;
}
m_abi = make_unique<BlockchainVariable>("abi", move(functions), m_context);
}
smtutil::Expression SymbolicState::abiFunction(frontend::FunctionCall const* _funCall)
{
solAssert(m_abi, "");
return m_abi->member(get<0>(m_abiMembers.at(_funCall)));
}
SymbolicState::SymbolicABIFunction const& SymbolicState::abiFunctionTypes(FunctionCall const* _funCall) const
{
return m_abiMembers.at(_funCall);
}