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diff --git a/clang/lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp b/clang/lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp
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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;
+
+ CheckerNameRef checkName_bcmp;
+ CheckerNameRef checkName_bcopy;
+ CheckerNameRef checkName_bzero;
+ CheckerNameRef checkName_gets;
+ CheckerNameRef checkName_getpw;
+ CheckerNameRef checkName_mktemp;
+ CheckerNameRef checkName_mkstemp;
+ CheckerNameRef checkName_strcpy;
+ CheckerNameRef checkName_DeprecatedOrUnsafeBufferHandling;
+ CheckerNameRef checkName_rand;
+ CheckerNameRef checkName_vfork;
+ CheckerNameRef checkName_FloatLoopCounter;
+ CheckerNameRef 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.
+//===----------------------------------------------------------------------===//
+
+// Returns either 'x' or 'y', depending on which one of them is incremented
+// in 'expr', or nullptr if none of them is incremented.
+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;
+
+ const VarDecl *vdInc = cast<VarDecl>(drInc->getDecl());
+ assert(vdInc && (vdInc == vdLHS || vdInc == vdRHS));
+
+ // Emit the error. First figure out which DeclRefExpr in the condition
+ // referenced the compared variable.
+ const DeclRefExpr *drCond = vdLHS == vdInc ? 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.getCurrentCheckerName(); \
+ } \
+ \
+ 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 2025-11-04 12:49:00 +0000