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-//==- CheckSecuritySyntaxOnly.cpp - Basic security checks --------*- C++ -*-==//
-//
-// 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
-//
-//===----------------------------------------------------------------------===//
-//
-// This file defines a set of flow-insensitive security checks.
-//
-//===----------------------------------------------------------------------===//
-
-#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
-#include "clang/AST/StmtVisitor.h"
-#include "clang/Analysis/AnalysisDeclContext.h"
-#include "clang/Basic/TargetInfo.h"
-#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
-#include "clang/StaticAnalyzer/Core/Checker.h"
-#include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h"
-#include "llvm/ADT/SmallString.h"
-#include "llvm/ADT/StringSwitch.h"
-#include "llvm/Support/raw_ostream.h"
-
-using namespace clang;
-using namespace ento;
-
-static bool isArc4RandomAvailable(const ASTContext &Ctx) {
- const llvm::Triple &T = Ctx.getTargetInfo().getTriple();
- return T.getVendor() == llvm::Triple::Apple ||
- T.getOS() == llvm::Triple::CloudABI ||
- T.isOSFreeBSD() ||
- T.isOSNetBSD() ||
- T.isOSOpenBSD() ||
- T.isOSDragonFly();
-}
-
-namespace {
-struct ChecksFilter {
- DefaultBool check_bcmp;
- DefaultBool check_bcopy;
- DefaultBool check_bzero;
- DefaultBool check_gets;
- DefaultBool check_getpw;
- DefaultBool check_mktemp;
- DefaultBool check_mkstemp;
- DefaultBool check_strcpy;
- DefaultBool check_DeprecatedOrUnsafeBufferHandling;
- DefaultBool check_rand;
- DefaultBool check_vfork;
- DefaultBool check_FloatLoopCounter;
- DefaultBool check_UncheckedReturn;
-
- CheckName checkName_bcmp;
- CheckName checkName_bcopy;
- CheckName checkName_bzero;
- CheckName checkName_gets;
- CheckName checkName_getpw;
- CheckName checkName_mktemp;
- CheckName checkName_mkstemp;
- CheckName checkName_strcpy;
- CheckName checkName_DeprecatedOrUnsafeBufferHandling;
- CheckName checkName_rand;
- CheckName checkName_vfork;
- CheckName checkName_FloatLoopCounter;
- CheckName checkName_UncheckedReturn;
-};
-
-class WalkAST : public StmtVisitor<WalkAST> {
- BugReporter &BR;
- AnalysisDeclContext* AC;
- enum { num_setids = 6 };
- IdentifierInfo *II_setid[num_setids];
-
- const bool CheckRand;
- const ChecksFilter &filter;
-
-public:
- WalkAST(BugReporter &br, AnalysisDeclContext* ac,
- const ChecksFilter &f)
- : BR(br), AC(ac), II_setid(),
- CheckRand(isArc4RandomAvailable(BR.getContext())),
- filter(f) {}
-
- // Statement visitor methods.
- void VisitCallExpr(CallExpr *CE);
- void VisitForStmt(ForStmt *S);
- void VisitCompoundStmt (CompoundStmt *S);
- void VisitStmt(Stmt *S) { VisitChildren(S); }
-
- void VisitChildren(Stmt *S);
-
- // Helpers.
- bool checkCall_strCommon(const CallExpr *CE, const FunctionDecl *FD);
-
- typedef void (WalkAST::*FnCheck)(const CallExpr *, const FunctionDecl *);
-
- // Checker-specific methods.
- void checkLoopConditionForFloat(const ForStmt *FS);
- void checkCall_bcmp(const CallExpr *CE, const FunctionDecl *FD);
- void checkCall_bcopy(const CallExpr *CE, const FunctionDecl *FD);
- void checkCall_bzero(const CallExpr *CE, const FunctionDecl *FD);
- void checkCall_gets(const CallExpr *CE, const FunctionDecl *FD);
- void checkCall_getpw(const CallExpr *CE, const FunctionDecl *FD);
- void checkCall_mktemp(const CallExpr *CE, const FunctionDecl *FD);
- void checkCall_mkstemp(const CallExpr *CE, const FunctionDecl *FD);
- void checkCall_strcpy(const CallExpr *CE, const FunctionDecl *FD);
- void checkCall_strcat(const CallExpr *CE, const FunctionDecl *FD);
- void checkDeprecatedOrUnsafeBufferHandling(const CallExpr *CE,
- const FunctionDecl *FD);
- void checkCall_rand(const CallExpr *CE, const FunctionDecl *FD);
- void checkCall_random(const CallExpr *CE, const FunctionDecl *FD);
- void checkCall_vfork(const CallExpr *CE, const FunctionDecl *FD);
- void checkUncheckedReturnValue(CallExpr *CE);
-};
-} // end anonymous namespace
-
-//===----------------------------------------------------------------------===//
-// AST walking.
-//===----------------------------------------------------------------------===//
-
-void WalkAST::VisitChildren(Stmt *S) {
- for (Stmt *Child : S->children())
- if (Child)
- Visit(Child);
-}
-
-void WalkAST::VisitCallExpr(CallExpr *CE) {
- // Get the callee.
- const FunctionDecl *FD = CE->getDirectCallee();
-
- if (!FD)
- return;
-
- // Get the name of the callee. If it's a builtin, strip off the prefix.
- IdentifierInfo *II = FD->getIdentifier();
- if (!II) // if no identifier, not a simple C function
- return;
- StringRef Name = II->getName();
- if (Name.startswith("__builtin_"))
- Name = Name.substr(10);
-
- // Set the evaluation function by switching on the callee name.
- FnCheck evalFunction = llvm::StringSwitch<FnCheck>(Name)
- .Case("bcmp", &WalkAST::checkCall_bcmp)
- .Case("bcopy", &WalkAST::checkCall_bcopy)
- .Case("bzero", &WalkAST::checkCall_bzero)
- .Case("gets", &WalkAST::checkCall_gets)
- .Case("getpw", &WalkAST::checkCall_getpw)
- .Case("mktemp", &WalkAST::checkCall_mktemp)
- .Case("mkstemp", &WalkAST::checkCall_mkstemp)
- .Case("mkdtemp", &WalkAST::checkCall_mkstemp)
- .Case("mkstemps", &WalkAST::checkCall_mkstemp)
- .Cases("strcpy", "__strcpy_chk", &WalkAST::checkCall_strcpy)
- .Cases("strcat", "__strcat_chk", &WalkAST::checkCall_strcat)
- .Cases("sprintf", "vsprintf", "scanf", "wscanf", "fscanf", "fwscanf",
- "vscanf", "vwscanf", "vfscanf", "vfwscanf",
- &WalkAST::checkDeprecatedOrUnsafeBufferHandling)
- .Cases("sscanf", "swscanf", "vsscanf", "vswscanf", "swprintf",
- "snprintf", "vswprintf", "vsnprintf", "memcpy", "memmove",
- &WalkAST::checkDeprecatedOrUnsafeBufferHandling)
- .Cases("strncpy", "strncat", "memset",
- &WalkAST::checkDeprecatedOrUnsafeBufferHandling)
- .Case("drand48", &WalkAST::checkCall_rand)
- .Case("erand48", &WalkAST::checkCall_rand)
- .Case("jrand48", &WalkAST::checkCall_rand)
- .Case("lrand48", &WalkAST::checkCall_rand)
- .Case("mrand48", &WalkAST::checkCall_rand)
- .Case("nrand48", &WalkAST::checkCall_rand)
- .Case("lcong48", &WalkAST::checkCall_rand)
- .Case("rand", &WalkAST::checkCall_rand)
- .Case("rand_r", &WalkAST::checkCall_rand)
- .Case("random", &WalkAST::checkCall_random)
- .Case("vfork", &WalkAST::checkCall_vfork)
- .Default(nullptr);
-
- // If the callee isn't defined, it is not of security concern.
- // Check and evaluate the call.
- if (evalFunction)
- (this->*evalFunction)(CE, FD);
-
- // Recurse and check children.
- VisitChildren(CE);
-}
-
-void WalkAST::VisitCompoundStmt(CompoundStmt *S) {
- for (Stmt *Child : S->children())
- if (Child) {
- if (CallExpr *CE = dyn_cast<CallExpr>(Child))
- checkUncheckedReturnValue(CE);
- Visit(Child);
- }
-}
-
-void WalkAST::VisitForStmt(ForStmt *FS) {
- checkLoopConditionForFloat(FS);
-
- // Recurse and check children.
- VisitChildren(FS);
-}
-
-//===----------------------------------------------------------------------===//
-// Check: floating point variable used as loop counter.
-// Originally: <rdar://problem/6336718>
-// Implements: CERT security coding advisory FLP-30.
-//===----------------------------------------------------------------------===//
-
-static const DeclRefExpr*
-getIncrementedVar(const Expr *expr, const VarDecl *x, const VarDecl *y) {
- expr = expr->IgnoreParenCasts();
-
- if (const BinaryOperator *B = dyn_cast<BinaryOperator>(expr)) {
- if (!(B->isAssignmentOp() || B->isCompoundAssignmentOp() ||
- B->getOpcode() == BO_Comma))
- return nullptr;
-
- if (const DeclRefExpr *lhs = getIncrementedVar(B->getLHS(), x, y))
- return lhs;
-
- if (const DeclRefExpr *rhs = getIncrementedVar(B->getRHS(), x, y))
- return rhs;
-
- return nullptr;
- }
-
- if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(expr)) {
- const NamedDecl *ND = DR->getDecl();
- return ND == x || ND == y ? DR : nullptr;
- }
-
- if (const UnaryOperator *U = dyn_cast<UnaryOperator>(expr))
- return U->isIncrementDecrementOp()
- ? getIncrementedVar(U->getSubExpr(), x, y) : nullptr;
-
- return nullptr;
-}
-
-/// CheckLoopConditionForFloat - This check looks for 'for' statements that
-/// use a floating point variable as a loop counter.
-/// CERT: FLP30-C, FLP30-CPP.
-///
-void WalkAST::checkLoopConditionForFloat(const ForStmt *FS) {
- if (!filter.check_FloatLoopCounter)
- return;
-
- // Does the loop have a condition?
- const Expr *condition = FS->getCond();
-
- if (!condition)
- return;
-
- // Does the loop have an increment?
- const Expr *increment = FS->getInc();
-
- if (!increment)
- return;
-
- // Strip away '()' and casts.
- condition = condition->IgnoreParenCasts();
- increment = increment->IgnoreParenCasts();
-
- // Is the loop condition a comparison?
- const BinaryOperator *B = dyn_cast<BinaryOperator>(condition);
-
- if (!B)
- return;
-
- // Is this a comparison?
- if (!(B->isRelationalOp() || B->isEqualityOp()))
- return;
-
- // Are we comparing variables?
- const DeclRefExpr *drLHS =
- dyn_cast<DeclRefExpr>(B->getLHS()->IgnoreParenLValueCasts());
- const DeclRefExpr *drRHS =
- dyn_cast<DeclRefExpr>(B->getRHS()->IgnoreParenLValueCasts());
-
- // Does at least one of the variables have a floating point type?
- drLHS = drLHS && drLHS->getType()->isRealFloatingType() ? drLHS : nullptr;
- drRHS = drRHS && drRHS->getType()->isRealFloatingType() ? drRHS : nullptr;
-
- if (!drLHS && !drRHS)
- return;
-
- const VarDecl *vdLHS = drLHS ? dyn_cast<VarDecl>(drLHS->getDecl()) : nullptr;
- const VarDecl *vdRHS = drRHS ? dyn_cast<VarDecl>(drRHS->getDecl()) : nullptr;
-
- if (!vdLHS && !vdRHS)
- return;
-
- // Does either variable appear in increment?
- const DeclRefExpr *drInc = getIncrementedVar(increment, vdLHS, vdRHS);
-
- if (!drInc)
- return;
-
- // Emit the error. First figure out which DeclRefExpr in the condition
- // referenced the compared variable.
- assert(drInc->getDecl());
- const DeclRefExpr *drCond = vdLHS == drInc->getDecl() ? drLHS : drRHS;
-
- SmallVector<SourceRange, 2> ranges;
- SmallString<256> sbuf;
- llvm::raw_svector_ostream os(sbuf);
-
- os << "Variable '" << drCond->getDecl()->getName()
- << "' with floating point type '" << drCond->getType().getAsString()
- << "' should not be used as a loop counter";
-
- ranges.push_back(drCond->getSourceRange());
- ranges.push_back(drInc->getSourceRange());
-
- const char *bugType = "Floating point variable used as loop counter";
-
- PathDiagnosticLocation FSLoc =
- PathDiagnosticLocation::createBegin(FS, BR.getSourceManager(), AC);
- BR.EmitBasicReport(AC->getDecl(), filter.checkName_FloatLoopCounter,
- bugType, "Security", os.str(),
- FSLoc, ranges);
-}
-
-//===----------------------------------------------------------------------===//
-// Check: Any use of bcmp.
-// CWE-477: Use of Obsolete Functions
-// bcmp was deprecated in POSIX.1-2008
-//===----------------------------------------------------------------------===//
-
-void WalkAST::checkCall_bcmp(const CallExpr *CE, const FunctionDecl *FD) {
- if (!filter.check_bcmp)
- return;
-
- const FunctionProtoType *FPT = FD->getType()->getAs<FunctionProtoType>();
- if (!FPT)
- return;
-
- // Verify that the function takes three arguments.
- if (FPT->getNumParams() != 3)
- return;
-
- for (int i = 0; i < 2; i++) {
- // Verify the first and second argument type is void*.
- const PointerType *PT = FPT->getParamType(i)->getAs<PointerType>();
- if (!PT)
- return;
-
- if (PT->getPointeeType().getUnqualifiedType() != BR.getContext().VoidTy)
- return;
- }
-
- // Verify the third argument type is integer.
- if (!FPT->getParamType(2)->isIntegralOrUnscopedEnumerationType())
- return;
-
- // Issue a warning.
- PathDiagnosticLocation CELoc =
- PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
- BR.EmitBasicReport(AC->getDecl(), filter.checkName_bcmp,
- "Use of deprecated function in call to 'bcmp()'",
- "Security",
- "The bcmp() function is obsoleted by memcmp().",
- CELoc, CE->getCallee()->getSourceRange());
-}
-
-//===----------------------------------------------------------------------===//
-// Check: Any use of bcopy.
-// CWE-477: Use of Obsolete Functions
-// bcopy was deprecated in POSIX.1-2008
-//===----------------------------------------------------------------------===//
-
-void WalkAST::checkCall_bcopy(const CallExpr *CE, const FunctionDecl *FD) {
- if (!filter.check_bcopy)
- return;
-
- const FunctionProtoType *FPT = FD->getType()->getAs<FunctionProtoType>();
- if (!FPT)
- return;
-
- // Verify that the function takes three arguments.
- if (FPT->getNumParams() != 3)
- return;
-
- for (int i = 0; i < 2; i++) {
- // Verify the first and second argument type is void*.
- const PointerType *PT = FPT->getParamType(i)->getAs<PointerType>();
- if (!PT)
- return;
-
- if (PT->getPointeeType().getUnqualifiedType() != BR.getContext().VoidTy)
- return;
- }
-
- // Verify the third argument type is integer.
- if (!FPT->getParamType(2)->isIntegralOrUnscopedEnumerationType())
- return;
-
- // Issue a warning.
- PathDiagnosticLocation CELoc =
- PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
- BR.EmitBasicReport(AC->getDecl(), filter.checkName_bcopy,
- "Use of deprecated function in call to 'bcopy()'",
- "Security",
- "The bcopy() function is obsoleted by memcpy() "
- "or memmove().",
- CELoc, CE->getCallee()->getSourceRange());
-}
-
-//===----------------------------------------------------------------------===//
-// Check: Any use of bzero.
-// CWE-477: Use of Obsolete Functions
-// bzero was deprecated in POSIX.1-2008
-//===----------------------------------------------------------------------===//
-
-void WalkAST::checkCall_bzero(const CallExpr *CE, const FunctionDecl *FD) {
- if (!filter.check_bzero)
- return;
-
- const FunctionProtoType *FPT = FD->getType()->getAs<FunctionProtoType>();
- if (!FPT)
- return;
-
- // Verify that the function takes two arguments.
- if (FPT->getNumParams() != 2)
- return;
-
- // Verify the first argument type is void*.
- const PointerType *PT = FPT->getParamType(0)->getAs<PointerType>();
- if (!PT)
- return;
-
- if (PT->getPointeeType().getUnqualifiedType() != BR.getContext().VoidTy)
- return;
-
- // Verify the second argument type is integer.
- if (!FPT->getParamType(1)->isIntegralOrUnscopedEnumerationType())
- return;
-
- // Issue a warning.
- PathDiagnosticLocation CELoc =
- PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
- BR.EmitBasicReport(AC->getDecl(), filter.checkName_bzero,
- "Use of deprecated function in call to 'bzero()'",
- "Security",
- "The bzero() function is obsoleted by memset().",
- CELoc, CE->getCallee()->getSourceRange());
-}
-
-
-//===----------------------------------------------------------------------===//
-// Check: Any use of 'gets' is insecure.
-// Originally: <rdar://problem/6335715>
-// Implements (part of): 300-BSI (buildsecurityin.us-cert.gov)
-// CWE-242: Use of Inherently Dangerous Function
-//===----------------------------------------------------------------------===//
-
-void WalkAST::checkCall_gets(const CallExpr *CE, const FunctionDecl *FD) {
- if (!filter.check_gets)
- return;
-
- const FunctionProtoType *FPT = FD->getType()->getAs<FunctionProtoType>();
- if (!FPT)
- return;
-
- // Verify that the function takes a single argument.
- if (FPT->getNumParams() != 1)
- return;
-
- // Is the argument a 'char*'?
- const PointerType *PT = FPT->getParamType(0)->getAs<PointerType>();
- if (!PT)
- return;
-
- if (PT->getPointeeType().getUnqualifiedType() != BR.getContext().CharTy)
- return;
-
- // Issue a warning.
- PathDiagnosticLocation CELoc =
- PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
- BR.EmitBasicReport(AC->getDecl(), filter.checkName_gets,
- "Potential buffer overflow in call to 'gets'",
- "Security",
- "Call to function 'gets' is extremely insecure as it can "
- "always result in a buffer overflow",
- CELoc, CE->getCallee()->getSourceRange());
-}
-
-//===----------------------------------------------------------------------===//
-// Check: Any use of 'getpwd' is insecure.
-// CWE-477: Use of Obsolete Functions
-//===----------------------------------------------------------------------===//
-
-void WalkAST::checkCall_getpw(const CallExpr *CE, const FunctionDecl *FD) {
- if (!filter.check_getpw)
- return;
-
- const FunctionProtoType *FPT = FD->getType()->getAs<FunctionProtoType>();
- if (!FPT)
- return;
-
- // Verify that the function takes two arguments.
- if (FPT->getNumParams() != 2)
- return;
-
- // Verify the first argument type is integer.
- if (!FPT->getParamType(0)->isIntegralOrUnscopedEnumerationType())
- return;
-
- // Verify the second argument type is char*.
- const PointerType *PT = FPT->getParamType(1)->getAs<PointerType>();
- if (!PT)
- return;
-
- if (PT->getPointeeType().getUnqualifiedType() != BR.getContext().CharTy)
- return;
-
- // Issue a warning.
- PathDiagnosticLocation CELoc =
- PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
- BR.EmitBasicReport(AC->getDecl(), filter.checkName_getpw,
- "Potential buffer overflow in call to 'getpw'",
- "Security",
- "The getpw() function is dangerous as it may overflow the "
- "provided buffer. It is obsoleted by getpwuid().",
- CELoc, CE->getCallee()->getSourceRange());
-}
-
-//===----------------------------------------------------------------------===//
-// Check: Any use of 'mktemp' is insecure. It is obsoleted by mkstemp().
-// CWE-377: Insecure Temporary File
-//===----------------------------------------------------------------------===//
-
-void WalkAST::checkCall_mktemp(const CallExpr *CE, const FunctionDecl *FD) {
- if (!filter.check_mktemp) {
- // Fall back to the security check of looking for enough 'X's in the
- // format string, since that is a less severe warning.
- checkCall_mkstemp(CE, FD);
- return;
- }
-
- const FunctionProtoType *FPT = FD->getType()->getAs<FunctionProtoType>();
- if(!FPT)
- return;
-
- // Verify that the function takes a single argument.
- if (FPT->getNumParams() != 1)
- return;
-
- // Verify that the argument is Pointer Type.
- const PointerType *PT = FPT->getParamType(0)->getAs<PointerType>();
- if (!PT)
- return;
-
- // Verify that the argument is a 'char*'.
- if (PT->getPointeeType().getUnqualifiedType() != BR.getContext().CharTy)
- return;
-
- // Issue a warning.
- PathDiagnosticLocation CELoc =
- PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
- BR.EmitBasicReport(AC->getDecl(), filter.checkName_mktemp,
- "Potential insecure temporary file in call 'mktemp'",
- "Security",
- "Call to function 'mktemp' is insecure as it always "
- "creates or uses insecure temporary file. Use 'mkstemp' "
- "instead",
- CELoc, CE->getCallee()->getSourceRange());
-}
-
-//===----------------------------------------------------------------------===//
-// Check: Use of 'mkstemp', 'mktemp', 'mkdtemp' should contain at least 6 X's.
-//===----------------------------------------------------------------------===//
-
-void WalkAST::checkCall_mkstemp(const CallExpr *CE, const FunctionDecl *FD) {
- if (!filter.check_mkstemp)
- return;
-
- StringRef Name = FD->getIdentifier()->getName();
- std::pair<signed, signed> ArgSuffix =
- llvm::StringSwitch<std::pair<signed, signed> >(Name)
- .Case("mktemp", std::make_pair(0,-1))
- .Case("mkstemp", std::make_pair(0,-1))
- .Case("mkdtemp", std::make_pair(0,-1))
- .Case("mkstemps", std::make_pair(0,1))
- .Default(std::make_pair(-1, -1));
-
- assert(ArgSuffix.first >= 0 && "Unsupported function");
-
- // Check if the number of arguments is consistent with out expectations.
- unsigned numArgs = CE->getNumArgs();
- if ((signed) numArgs <= ArgSuffix.first)
- return;
-
- const StringLiteral *strArg =
- dyn_cast<StringLiteral>(CE->getArg((unsigned)ArgSuffix.first)
- ->IgnoreParenImpCasts());
-
- // Currently we only handle string literals. It is possible to do better,
- // either by looking at references to const variables, or by doing real
- // flow analysis.
- if (!strArg || strArg->getCharByteWidth() != 1)
- return;
-
- // Count the number of X's, taking into account a possible cutoff suffix.
- StringRef str = strArg->getString();
- unsigned numX = 0;
- unsigned n = str.size();
-
- // Take into account the suffix.
- unsigned suffix = 0;
- if (ArgSuffix.second >= 0) {
- const Expr *suffixEx = CE->getArg((unsigned)ArgSuffix.second);
- Expr::EvalResult EVResult;
- if (!suffixEx->EvaluateAsInt(EVResult, BR.getContext()))
- return;
- llvm::APSInt Result = EVResult.Val.getInt();
- // FIXME: Issue a warning.
- if (Result.isNegative())
- return;
- suffix = (unsigned) Result.getZExtValue();
- n = (n > suffix) ? n - suffix : 0;
- }
-
- for (unsigned i = 0; i < n; ++i)
- if (str[i] == 'X') ++numX;
-
- if (numX >= 6)
- return;
-
- // Issue a warning.
- PathDiagnosticLocation CELoc =
- PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
- SmallString<512> buf;
- llvm::raw_svector_ostream out(buf);
- out << "Call to '" << Name << "' should have at least 6 'X's in the"
- " format string to be secure (" << numX << " 'X'";
- if (numX != 1)
- out << 's';
- out << " seen";
- if (suffix) {
- out << ", " << suffix << " character";
- if (suffix > 1)
- out << 's';
- out << " used as a suffix";
- }
- out << ')';
- BR.EmitBasicReport(AC->getDecl(), filter.checkName_mkstemp,
- "Insecure temporary file creation", "Security",
- out.str(), CELoc, strArg->getSourceRange());
-}
-
-//===----------------------------------------------------------------------===//
-// Check: Any use of 'strcpy' is insecure.
-//
-// CWE-119: Improper Restriction of Operations within
-// the Bounds of a Memory Buffer
-//===----------------------------------------------------------------------===//
-
-void WalkAST::checkCall_strcpy(const CallExpr *CE, const FunctionDecl *FD) {
- if (!filter.check_strcpy)
- return;
-
- if (!checkCall_strCommon(CE, FD))
- return;
-
- const auto *Target = CE->getArg(0)->IgnoreImpCasts(),
- *Source = CE->getArg(1)->IgnoreImpCasts();
-
- if (const auto *Array = dyn_cast<ConstantArrayType>(Target->getType())) {
- uint64_t ArraySize = BR.getContext().getTypeSize(Array) / 8;
- if (const auto *String = dyn_cast<StringLiteral>(Source)) {
- if (ArraySize >= String->getLength() + 1)
- return;
- }
- }
-
- // Issue a warning.
- PathDiagnosticLocation CELoc =
- PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
- BR.EmitBasicReport(AC->getDecl(), filter.checkName_strcpy,
- "Potential insecure memory buffer bounds restriction in "
- "call 'strcpy'",
- "Security",
- "Call to function 'strcpy' is insecure as it does not "
- "provide bounding of the memory buffer. Replace "
- "unbounded copy functions with analogous functions that "
- "support length arguments such as 'strlcpy'. CWE-119.",
- CELoc, CE->getCallee()->getSourceRange());
-}
-
-//===----------------------------------------------------------------------===//
-// Check: Any use of 'strcat' is insecure.
-//
-// CWE-119: Improper Restriction of Operations within
-// the Bounds of a Memory Buffer
-//===----------------------------------------------------------------------===//
-
-void WalkAST::checkCall_strcat(const CallExpr *CE, const FunctionDecl *FD) {
- if (!filter.check_strcpy)
- return;
-
- if (!checkCall_strCommon(CE, FD))
- return;
-
- // Issue a warning.
- PathDiagnosticLocation CELoc =
- PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
- BR.EmitBasicReport(AC->getDecl(), filter.checkName_strcpy,
- "Potential insecure memory buffer bounds restriction in "
- "call 'strcat'",
- "Security",
- "Call to function 'strcat' is insecure as it does not "
- "provide bounding of the memory buffer. Replace "
- "unbounded copy functions with analogous functions that "
- "support length arguments such as 'strlcat'. CWE-119.",
- CELoc, CE->getCallee()->getSourceRange());
-}
-
-//===----------------------------------------------------------------------===//
-// Check: Any use of 'sprintf', 'vsprintf', 'scanf', 'wscanf', 'fscanf',
-// 'fwscanf', 'vscanf', 'vwscanf', 'vfscanf', 'vfwscanf', 'sscanf',
-// 'swscanf', 'vsscanf', 'vswscanf', 'swprintf', 'snprintf', 'vswprintf',
-// 'vsnprintf', 'memcpy', 'memmove', 'strncpy', 'strncat', 'memset'
-// is deprecated since C11.
-//
-// Use of 'sprintf', 'vsprintf', 'scanf', 'wscanf','fscanf',
-// 'fwscanf', 'vscanf', 'vwscanf', 'vfscanf', 'vfwscanf', 'sscanf',
-// 'swscanf', 'vsscanf', 'vswscanf' without buffer limitations
-// is insecure.
-//
-// CWE-119: Improper Restriction of Operations within
-// the Bounds of a Memory Buffer
-//===----------------------------------------------------------------------===//
-
-void WalkAST::checkDeprecatedOrUnsafeBufferHandling(const CallExpr *CE,
- const FunctionDecl *FD) {
- if (!filter.check_DeprecatedOrUnsafeBufferHandling)
- return;
-
- if (!BR.getContext().getLangOpts().C11)
- return;
-
- // Issue a warning. ArgIndex == -1: Deprecated but not unsafe (has size
- // restrictions).
- enum { DEPR_ONLY = -1, UNKNOWN_CALL = -2 };
-
- StringRef Name = FD->getIdentifier()->getName();
- if (Name.startswith("__builtin_"))
- Name = Name.substr(10);
-
- int ArgIndex =
- llvm::StringSwitch<int>(Name)
- .Cases("scanf", "wscanf", "vscanf", "vwscanf", 0)
- .Cases("sprintf", "vsprintf", "fscanf", "fwscanf", "vfscanf",
- "vfwscanf", "sscanf", "swscanf", "vsscanf", "vswscanf", 1)
- .Cases("swprintf", "snprintf", "vswprintf", "vsnprintf", "memcpy",
- "memmove", "memset", "strncpy", "strncat", DEPR_ONLY)
- .Default(UNKNOWN_CALL);
-
- assert(ArgIndex != UNKNOWN_CALL && "Unsupported function");
- bool BoundsProvided = ArgIndex == DEPR_ONLY;
-
- if (!BoundsProvided) {
- // Currently we only handle (not wide) string literals. It is possible to do
- // better, either by looking at references to const variables, or by doing
- // real flow analysis.
- auto FormatString =
- dyn_cast<StringLiteral>(CE->getArg(ArgIndex)->IgnoreParenImpCasts());
- if (FormatString &&
- FormatString->getString().find("%s") == StringRef::npos &&
- FormatString->getString().find("%[") == StringRef::npos)
- BoundsProvided = true;
- }
-
- SmallString<128> Buf1;
- SmallString<512> Buf2;
- llvm::raw_svector_ostream Out1(Buf1);
- llvm::raw_svector_ostream Out2(Buf2);
-
- Out1 << "Potential insecure memory buffer bounds restriction in call '"
- << Name << "'";
- Out2 << "Call to function '" << Name
- << "' is insecure as it does not provide ";
-
- if (!BoundsProvided) {
- Out2 << "bounding of the memory buffer or ";
- }
-
- Out2 << "security checks introduced "
- "in the C11 standard. Replace with analogous functions that "
- "support length arguments or provides boundary checks such as '"
- << Name << "_s' in case of C11";
-
- PathDiagnosticLocation CELoc =
- PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
- BR.EmitBasicReport(AC->getDecl(),
- filter.checkName_DeprecatedOrUnsafeBufferHandling,
- Out1.str(), "Security", Out2.str(), CELoc,
- CE->getCallee()->getSourceRange());
-}
-
-//===----------------------------------------------------------------------===//
-// Common check for str* functions with no bounds parameters.
-//===----------------------------------------------------------------------===//
-
-bool WalkAST::checkCall_strCommon(const CallExpr *CE, const FunctionDecl *FD) {
- const FunctionProtoType *FPT = FD->getType()->getAs<FunctionProtoType>();
- if (!FPT)
- return false;
-
- // Verify the function takes two arguments, three in the _chk version.
- int numArgs = FPT->getNumParams();
- if (numArgs != 2 && numArgs != 3)
- return false;
-
- // Verify the type for both arguments.
- for (int i = 0; i < 2; i++) {
- // Verify that the arguments are pointers.
- const PointerType *PT = FPT->getParamType(i)->getAs<PointerType>();
- if (!PT)
- return false;
-
- // Verify that the argument is a 'char*'.
- if (PT->getPointeeType().getUnqualifiedType() != BR.getContext().CharTy)
- return false;
- }
-
- return true;
-}
-
-//===----------------------------------------------------------------------===//
-// Check: Linear congruent random number generators should not be used
-// Originally: <rdar://problem/63371000>
-// CWE-338: Use of cryptographically weak prng
-//===----------------------------------------------------------------------===//
-
-void WalkAST::checkCall_rand(const CallExpr *CE, const FunctionDecl *FD) {
- if (!filter.check_rand || !CheckRand)
- return;
-
- const FunctionProtoType *FTP = FD->getType()->getAs<FunctionProtoType>();
- if (!FTP)
- return;
-
- if (FTP->getNumParams() == 1) {
- // Is the argument an 'unsigned short *'?
- // (Actually any integer type is allowed.)
- const PointerType *PT = FTP->getParamType(0)->getAs<PointerType>();
- if (!PT)
- return;
-
- if (! PT->getPointeeType()->isIntegralOrUnscopedEnumerationType())
- return;
- } else if (FTP->getNumParams() != 0)
- return;
-
- // Issue a warning.
- SmallString<256> buf1;
- llvm::raw_svector_ostream os1(buf1);
- os1 << '\'' << *FD << "' is a poor random number generator";
-
- SmallString<256> buf2;
- llvm::raw_svector_ostream os2(buf2);
- os2 << "Function '" << *FD
- << "' is obsolete because it implements a poor random number generator."
- << " Use 'arc4random' instead";
-
- PathDiagnosticLocation CELoc =
- PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
- BR.EmitBasicReport(AC->getDecl(), filter.checkName_rand, os1.str(),
- "Security", os2.str(), CELoc,
- CE->getCallee()->getSourceRange());
-}
-
-//===----------------------------------------------------------------------===//
-// Check: 'random' should not be used
-// Originally: <rdar://problem/63371000>
-//===----------------------------------------------------------------------===//
-
-void WalkAST::checkCall_random(const CallExpr *CE, const FunctionDecl *FD) {
- if (!CheckRand || !filter.check_rand)
- return;
-
- const FunctionProtoType *FTP = FD->getType()->getAs<FunctionProtoType>();
- if (!FTP)
- return;
-
- // Verify that the function takes no argument.
- if (FTP->getNumParams() != 0)
- return;
-
- // Issue a warning.
- PathDiagnosticLocation CELoc =
- PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
- BR.EmitBasicReport(AC->getDecl(), filter.checkName_rand,
- "'random' is not a secure random number generator",
- "Security",
- "The 'random' function produces a sequence of values that "
- "an adversary may be able to predict. Use 'arc4random' "
- "instead", CELoc, CE->getCallee()->getSourceRange());
-}
-
-//===----------------------------------------------------------------------===//
-// Check: 'vfork' should not be used.
-// POS33-C: Do not use vfork().
-//===----------------------------------------------------------------------===//
-
-void WalkAST::checkCall_vfork(const CallExpr *CE, const FunctionDecl *FD) {
- if (!filter.check_vfork)
- return;
-
- // All calls to vfork() are insecure, issue a warning.
- PathDiagnosticLocation CELoc =
- PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
- BR.EmitBasicReport(AC->getDecl(), filter.checkName_vfork,
- "Potential insecure implementation-specific behavior in "
- "call 'vfork'",
- "Security",
- "Call to function 'vfork' is insecure as it can lead to "
- "denial of service situations in the parent process. "
- "Replace calls to vfork with calls to the safer "
- "'posix_spawn' function",
- CELoc, CE->getCallee()->getSourceRange());
-}
-
-//===----------------------------------------------------------------------===//
-// Check: Should check whether privileges are dropped successfully.
-// Originally: <rdar://problem/6337132>
-//===----------------------------------------------------------------------===//
-
-void WalkAST::checkUncheckedReturnValue(CallExpr *CE) {
- if (!filter.check_UncheckedReturn)
- return;
-
- const FunctionDecl *FD = CE->getDirectCallee();
- if (!FD)
- return;
-
- if (II_setid[0] == nullptr) {
- static const char * const identifiers[num_setids] = {
- "setuid", "setgid", "seteuid", "setegid",
- "setreuid", "setregid"
- };
-
- for (size_t i = 0; i < num_setids; i++)
- II_setid[i] = &BR.getContext().Idents.get(identifiers[i]);
- }
-
- const IdentifierInfo *id = FD->getIdentifier();
- size_t identifierid;
-
- for (identifierid = 0; identifierid < num_setids; identifierid++)
- if (id == II_setid[identifierid])
- break;
-
- if (identifierid >= num_setids)
- return;
-
- const FunctionProtoType *FTP = FD->getType()->getAs<FunctionProtoType>();
- if (!FTP)
- return;
-
- // Verify that the function takes one or two arguments (depending on
- // the function).
- if (FTP->getNumParams() != (identifierid < 4 ? 1 : 2))
- return;
-
- // The arguments must be integers.
- for (unsigned i = 0; i < FTP->getNumParams(); i++)
- if (!FTP->getParamType(i)->isIntegralOrUnscopedEnumerationType())
- return;
-
- // Issue a warning.
- SmallString<256> buf1;
- llvm::raw_svector_ostream os1(buf1);
- os1 << "Return value is not checked in call to '" << *FD << '\'';
-
- SmallString<256> buf2;
- llvm::raw_svector_ostream os2(buf2);
- os2 << "The return value from the call to '" << *FD
- << "' is not checked. If an error occurs in '" << *FD
- << "', the following code may execute with unexpected privileges";
-
- PathDiagnosticLocation CELoc =
- PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
- BR.EmitBasicReport(AC->getDecl(), filter.checkName_UncheckedReturn, os1.str(),
- "Security", os2.str(), CELoc,
- CE->getCallee()->getSourceRange());
-}
-
-//===----------------------------------------------------------------------===//
-// SecuritySyntaxChecker
-//===----------------------------------------------------------------------===//
-
-namespace {
-class SecuritySyntaxChecker : public Checker<check::ASTCodeBody> {
-public:
- ChecksFilter filter;
-
- void checkASTCodeBody(const Decl *D, AnalysisManager& mgr,
- BugReporter &BR) const {
- WalkAST walker(BR, mgr.getAnalysisDeclContext(D), filter);
- walker.Visit(D->getBody());
- }
-};
-}
-
-void ento::registerSecuritySyntaxChecker(CheckerManager &mgr) {
- mgr.registerChecker<SecuritySyntaxChecker>();
-}
-
-bool ento::shouldRegisterSecuritySyntaxChecker(const LangOptions &LO) {
- return true;
-}
-
-#define REGISTER_CHECKER(name) \
- void ento::register##name(CheckerManager &mgr) { \
- SecuritySyntaxChecker *checker = mgr.getChecker<SecuritySyntaxChecker>(); \
- checker->filter.check_##name = true; \
- checker->filter.checkName_##name = mgr.getCurrentCheckName(); \
- } \
- \
- bool ento::shouldRegister##name(const LangOptions &LO) { \
- return true; \
- }
-
-REGISTER_CHECKER(bcmp)
-REGISTER_CHECKER(bcopy)
-REGISTER_CHECKER(bzero)
-REGISTER_CHECKER(gets)
-REGISTER_CHECKER(getpw)
-REGISTER_CHECKER(mkstemp)
-REGISTER_CHECKER(mktemp)
-REGISTER_CHECKER(strcpy)
-REGISTER_CHECKER(rand)
-REGISTER_CHECKER(vfork)
-REGISTER_CHECKER(FloatLoopCounter)
-REGISTER_CHECKER(UncheckedReturn)
-REGISTER_CHECKER(DeprecatedOrUnsafeBufferHandling)
generated by cgit v1.2.3 (git 2.25.1) at 2025-10-16 07:32:01 +0000