126 lines
4.0 KiB
C++
126 lines
4.0 KiB
C++
//===--- ProperlySeededRandomGeneratorCheck.cpp - clang-tidy---------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "ProperlySeededRandomGeneratorCheck.h"
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#include "clang/AST/ASTContext.h"
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#include "clang/ASTMatchers/ASTMatchFinder.h"
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#include "llvm/ADT/STLExtras.h"
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using namespace clang::ast_matchers;
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namespace clang {
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namespace tidy {
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namespace cert {
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ProperlySeededRandomGeneratorCheck::ProperlySeededRandomGeneratorCheck(
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StringRef Name, ClangTidyContext *Context)
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: ClangTidyCheck(Name, Context),
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RawDisallowedSeedTypes(
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Options.get("DisallowedSeedTypes", "time_t,std::time_t")) {
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StringRef(RawDisallowedSeedTypes).split(DisallowedSeedTypes, ',');
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}
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void ProperlySeededRandomGeneratorCheck::storeOptions(
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ClangTidyOptions::OptionMap &Opts) {
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Options.store(Opts, "DisallowedSeedTypes", RawDisallowedSeedTypes);
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}
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void ProperlySeededRandomGeneratorCheck::registerMatchers(MatchFinder *Finder) {
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auto RandomGeneratorEngineDecl = cxxRecordDecl(hasAnyName(
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"::std::linear_congruential_engine", "::std::mersenne_twister_engine",
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"::std::subtract_with_carry_engine", "::std::discard_block_engine",
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"::std::independent_bits_engine", "::std::shuffle_order_engine"));
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auto RandomGeneratorEngineTypeMatcher = hasType(hasUnqualifiedDesugaredType(
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recordType(hasDeclaration(RandomGeneratorEngineDecl))));
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// std::mt19937 engine;
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// engine.seed();
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// ^
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// engine.seed(1);
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// ^
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// const int x = 1;
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// engine.seed(x);
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// ^
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Finder->addMatcher(
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cxxMemberCallExpr(
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has(memberExpr(has(declRefExpr(RandomGeneratorEngineTypeMatcher)),
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member(hasName("seed")),
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unless(hasDescendant(cxxThisExpr())))))
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.bind("seed"),
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this);
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// std::mt19937 engine;
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// ^
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// std::mt19937 engine(1);
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// ^
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// const int x = 1;
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// std::mt19937 engine(x);
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// ^
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Finder->addMatcher(
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traverse(TK_AsIs,
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cxxConstructExpr(RandomGeneratorEngineTypeMatcher).bind("ctor")),
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this);
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// srand();
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// ^
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// const int x = 1;
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// srand(x);
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// ^
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Finder->addMatcher(
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callExpr(callee(functionDecl(hasAnyName("::srand", "::std::srand"))))
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.bind("srand"),
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this);
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}
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void ProperlySeededRandomGeneratorCheck::check(
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const MatchFinder::MatchResult &Result) {
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const auto *Ctor = Result.Nodes.getNodeAs<CXXConstructExpr>("ctor");
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if (Ctor)
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checkSeed(Result, Ctor);
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const auto *Func = Result.Nodes.getNodeAs<CXXMemberCallExpr>("seed");
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if (Func)
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checkSeed(Result, Func);
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const auto *Srand = Result.Nodes.getNodeAs<CallExpr>("srand");
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if (Srand)
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checkSeed(Result, Srand);
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}
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template <class T>
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void ProperlySeededRandomGeneratorCheck::checkSeed(
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const MatchFinder::MatchResult &Result, const T *Func) {
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if (Func->getNumArgs() == 0 || Func->getArg(0)->isDefaultArgument()) {
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diag(Func->getExprLoc(),
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"random number generator seeded with a default argument will generate "
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"a predictable sequence of values");
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return;
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}
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Expr::EvalResult EVResult;
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if (Func->getArg(0)->EvaluateAsInt(EVResult, *Result.Context)) {
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diag(Func->getExprLoc(),
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"random number generator seeded with a constant value will generate a "
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"predictable sequence of values");
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return;
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}
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const std::string SeedType(
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Func->getArg(0)->IgnoreCasts()->getType().getAsString());
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if (llvm::find(DisallowedSeedTypes, SeedType) != DisallowedSeedTypes.end()) {
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diag(Func->getExprLoc(),
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"random number generator seeded with a disallowed source of seed "
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"value will generate a predictable sequence of values");
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return;
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}
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}
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} // namespace cert
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} // namespace tidy
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} // namespace clang
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