| //===--- UnsafeFunctionsCheck.cpp - clang-tidy ----------------------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "UnsafeFunctionsCheck.h" |
| #include "clang/AST/ASTContext.h" |
| #include "clang/ASTMatchers/ASTMatchFinder.h" |
| #include "clang/Lex/PPCallbacks.h" |
| #include "clang/Lex/Preprocessor.h" |
| #include <cassert> |
| |
| using namespace clang::ast_matchers; |
| using namespace llvm; |
| |
| namespace clang { |
| namespace tidy { |
| namespace bugprone { |
| |
| static constexpr llvm::StringLiteral OptionNameReportMoreUnsafeFunctions = |
| "ReportMoreUnsafeFunctions"; |
| |
| static constexpr llvm::StringLiteral FunctionNamesWithAnnexKReplacementId = |
| "FunctionNamesWithAnnexKReplacement"; |
| static constexpr llvm::StringLiteral FunctionNamesId = "FunctionsNames"; |
| static constexpr llvm::StringLiteral AdditionalFunctionNamesId = |
| "AdditionalFunctionsNames"; |
| static constexpr llvm::StringLiteral DeclRefId = "DRE"; |
| |
| static std::optional<std::string> |
| getAnnexKReplacementFor(StringRef FunctionName) { |
| return StringSwitch<std::string>(FunctionName) |
| .Case("strlen", "strnlen_s") |
| .Case("wcslen", "wcsnlen_s") |
| .Default((Twine{FunctionName} + "_s").str()); |
| } |
| |
| static StringRef getReplacementFor(StringRef FunctionName, |
| bool IsAnnexKAvailable) { |
| if (IsAnnexKAvailable) { |
| // Try to find a better replacement from Annex K first. |
| StringRef AnnexKReplacementFunction = |
| StringSwitch<StringRef>(FunctionName) |
| .Cases("asctime", "asctime_r", "asctime_s") |
| .Case("gets", "gets_s") |
| .Default({}); |
| if (!AnnexKReplacementFunction.empty()) |
| return AnnexKReplacementFunction; |
| } |
| |
| // FIXME: Some of these functions are available in C++ under "std::", and |
| // should be matched and suggested. |
| return StringSwitch<StringRef>(FunctionName) |
| .Cases("asctime", "asctime_r", "strftime") |
| .Case("gets", "fgets") |
| .Case("rewind", "fseek") |
| .Case("setbuf", "setvbuf"); |
| } |
| |
| static StringRef getReplacementForAdditional(StringRef FunctionName, |
| bool IsAnnexKAvailable) { |
| if (IsAnnexKAvailable) { |
| // Try to find a better replacement from Annex K first. |
| StringRef AnnexKReplacementFunction = StringSwitch<StringRef>(FunctionName) |
| .Case("bcopy", "memcpy_s") |
| .Case("bzero", "memset_s") |
| .Default({}); |
| |
| if (!AnnexKReplacementFunction.empty()) |
| return AnnexKReplacementFunction; |
| } |
| |
| return StringSwitch<StringRef>(FunctionName) |
| .Case("bcmp", "memcmp") |
| .Case("bcopy", "memcpy") |
| .Case("bzero", "memset") |
| .Case("getpw", "getpwuid") |
| .Case("vfork", "posix_spawn"); |
| } |
| |
| /// \returns The rationale for replacing the function \p FunctionName with the |
| /// safer alternative. |
| static StringRef getRationaleFor(StringRef FunctionName) { |
| return StringSwitch<StringRef>(FunctionName) |
| .Cases("asctime", "asctime_r", "ctime", |
| "is not bounds-checking and non-reentrant") |
| .Cases("bcmp", "bcopy", "bzero", "is deprecated") |
| .Cases("fopen", "freopen", "has no exclusive access to the opened file") |
| .Case("gets", "is insecure, was deprecated and removed in C11 and C++14") |
| .Case("getpw", "is dangerous as it may overflow the provided buffer") |
| .Cases("rewind", "setbuf", "has no error detection") |
| .Case("vfork", "is insecure as it can lead to denial of service " |
| "situations in the parent process") |
| .Default("is not bounds-checking"); |
| } |
| |
| /// Calculates whether Annex K is available for the current translation unit |
| /// based on the macro definitions and the language options. |
| /// |
| /// The result is cached and saved in \p CacheVar. |
| static bool isAnnexKAvailable(std::optional<bool> &CacheVar, Preprocessor *PP, |
| const LangOptions &LO) { |
| if (CacheVar.has_value()) |
| return *CacheVar; |
| |
| if (!LO.C11) |
| // TODO: How is "Annex K" available in C++ mode? |
| return (CacheVar = false).value(); |
| |
| assert(PP && "No Preprocessor registered."); |
| |
| if (!PP->isMacroDefined("__STDC_LIB_EXT1__") || |
| !PP->isMacroDefined("__STDC_WANT_LIB_EXT1__")) |
| return (CacheVar = false).value(); |
| |
| const auto *MI = |
| PP->getMacroInfo(PP->getIdentifierInfo("__STDC_WANT_LIB_EXT1__")); |
| if (!MI || MI->tokens_empty()) |
| return (CacheVar = false).value(); |
| |
| const Token &T = MI->tokens().back(); |
| if (!T.isLiteral() || !T.getLiteralData()) |
| return (CacheVar = false).value(); |
| |
| CacheVar = StringRef(T.getLiteralData(), T.getLength()) == "1"; |
| return CacheVar.value(); |
| } |
| |
| UnsafeFunctionsCheck::UnsafeFunctionsCheck(StringRef Name, |
| ClangTidyContext *Context) |
| : ClangTidyCheck(Name, Context), |
| ReportMoreUnsafeFunctions( |
| Options.get(OptionNameReportMoreUnsafeFunctions, true)) {} |
| |
| void UnsafeFunctionsCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) { |
| Options.store(Opts, OptionNameReportMoreUnsafeFunctions, |
| ReportMoreUnsafeFunctions); |
| } |
| |
| void UnsafeFunctionsCheck::registerMatchers(MatchFinder *Finder) { |
| if (getLangOpts().C11) { |
| // Matching functions with safe replacements only in Annex K. |
| auto FunctionNamesWithAnnexKReplacementMatcher = hasAnyName( |
| "::bsearch", "::ctime", "::fopen", "::fprintf", "::freopen", "::fscanf", |
| "::fwprintf", "::fwscanf", "::getenv", "::gmtime", "::localtime", |
| "::mbsrtowcs", "::mbstowcs", "::memcpy", "::memmove", "::memset", |
| "::printf", "::qsort", "::scanf", "::snprintf", "::sprintf", "::sscanf", |
| "::strcat", "::strcpy", "::strerror", "::strlen", "::strncat", |
| "::strncpy", "::strtok", "::swprintf", "::swscanf", "::vfprintf", |
| "::vfscanf", "::vfwprintf", "::vfwscanf", "::vprintf", "::vscanf", |
| "::vsnprintf", "::vsprintf", "::vsscanf", "::vswprintf", "::vswscanf", |
| "::vwprintf", "::vwscanf", "::wcrtomb", "::wcscat", "::wcscpy", |
| "::wcslen", "::wcsncat", "::wcsncpy", "::wcsrtombs", "::wcstok", |
| "::wcstombs", "::wctomb", "::wmemcpy", "::wmemmove", "::wprintf", |
| "::wscanf"); |
| Finder->addMatcher( |
| declRefExpr(to(functionDecl(FunctionNamesWithAnnexKReplacementMatcher) |
| .bind(FunctionNamesWithAnnexKReplacementId))) |
| .bind(DeclRefId), |
| this); |
| } |
| |
| // Matching functions with replacements without Annex K. |
| auto FunctionNamesMatcher = |
| hasAnyName("::asctime", "asctime_r", "::gets", "::rewind", "::setbuf"); |
| Finder->addMatcher( |
| declRefExpr(to(functionDecl(FunctionNamesMatcher).bind(FunctionNamesId))) |
| .bind(DeclRefId), |
| this); |
| |
| if (ReportMoreUnsafeFunctions) { |
| // Matching functions with replacements without Annex K, at user request. |
| auto AdditionalFunctionNamesMatcher = |
| hasAnyName("::bcmp", "::bcopy", "::bzero", "::getpw", "::vfork"); |
| Finder->addMatcher( |
| declRefExpr(to(functionDecl(AdditionalFunctionNamesMatcher) |
| .bind(AdditionalFunctionNamesId))) |
| .bind(DeclRefId), |
| this); |
| } |
| } |
| |
| void UnsafeFunctionsCheck::check(const MatchFinder::MatchResult &Result) { |
| const auto *DeclRef = Result.Nodes.getNodeAs<DeclRefExpr>(DeclRefId); |
| const auto *FuncDecl = cast<FunctionDecl>(DeclRef->getDecl()); |
| assert(DeclRef && FuncDecl && "No valid matched node in check()"); |
| |
| const auto *AnnexK = Result.Nodes.getNodeAs<FunctionDecl>( |
| FunctionNamesWithAnnexKReplacementId); |
| const auto *Normal = Result.Nodes.getNodeAs<FunctionDecl>(FunctionNamesId); |
| const auto *Additional = |
| Result.Nodes.getNodeAs<FunctionDecl>(AdditionalFunctionNamesId); |
| assert((AnnexK || Normal || Additional) && "No valid match category."); |
| |
| bool AnnexKIsAvailable = |
| isAnnexKAvailable(IsAnnexKAvailable, PP, getLangOpts()); |
| StringRef FunctionName = FuncDecl->getName(); |
| const std::optional<std::string> ReplacementFunctionName = |
| [&]() -> std::optional<std::string> { |
| if (AnnexK) { |
| if (AnnexKIsAvailable) |
| return getAnnexKReplacementFor(FunctionName); |
| return std::nullopt; |
| } |
| |
| if (Normal) |
| return getReplacementFor(FunctionName, AnnexKIsAvailable).str(); |
| |
| if (Additional) |
| return getReplacementForAdditional(FunctionName, AnnexKIsAvailable).str(); |
| |
| llvm_unreachable("Unhandled match category"); |
| }(); |
| if (!ReplacementFunctionName) |
| return; |
| |
| diag(DeclRef->getExprLoc(), "function %0 %1; '%2' should be used instead") |
| << FuncDecl << getRationaleFor(FunctionName) |
| << ReplacementFunctionName.value() << DeclRef->getSourceRange(); |
| } |
| |
| void UnsafeFunctionsCheck::registerPPCallbacks( |
| const SourceManager &SM, Preprocessor *PP, |
| Preprocessor * /*ModuleExpanderPP*/) { |
| this->PP = PP; |
| } |
| |
| void UnsafeFunctionsCheck::onEndOfTranslationUnit() { |
| this->PP = nullptr; |
| IsAnnexKAvailable.reset(); |
| } |
| |
| } // namespace bugprone |
| } // namespace tidy |
| } // namespace clang |
