| //==- CheckSecuritySyntaxOnly.cpp - Basic security checks --------*- C++ -*-==// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file defines a set of flow-insensitive security checks. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "ClangSACheckers.h" |
| #include "clang/Analysis/AnalysisContext.h" |
| #include "clang/AST/StmtVisitor.h" |
| #include "clang/Basic/TargetInfo.h" |
| #include "clang/StaticAnalyzer/Core/Checker.h" |
| #include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.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::FreeBSD || |
| T.getOS() == llvm::Triple::NetBSD || |
| T.getOS() == llvm::Triple::OpenBSD || |
| T.getOS() == llvm::Triple::DragonFly; |
| } |
| |
| namespace { |
| struct DefaultBool { |
| bool val; |
| DefaultBool() : val(false) {} |
| operator bool() const { return val; } |
| DefaultBool &operator=(bool b) { val = b; return *this; } |
| }; |
| |
| struct ChecksFilter { |
| DefaultBool check_gets; |
| DefaultBool check_getpw; |
| DefaultBool check_mktemp; |
| DefaultBool check_mkstemp; |
| DefaultBool check_strcpy; |
| DefaultBool check_rand; |
| DefaultBool check_vfork; |
| DefaultBool check_FloatLoopCounter; |
| DefaultBool check_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_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 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_iterator I = S->child_begin(), E = S->child_end(); I!=E; ++I) |
| if (Stmt *child = *I) |
| 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("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) |
| .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(NULL); |
| |
| // 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_iterator I = S->child_begin(), E = S->child_end(); I!=E; ++I) |
| if (Stmt *child = *I) { |
| 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 poing 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 NULL; |
| |
| if (const DeclRefExpr *lhs = getIncrementedVar(B->getLHS(), x, y)) |
| return lhs; |
| |
| if (const DeclRefExpr *rhs = getIncrementedVar(B->getRHS(), x, y)) |
| return rhs; |
| |
| return NULL; |
| } |
| |
| if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(expr)) { |
| const NamedDecl *ND = DR->getDecl(); |
| return ND == x || ND == y ? DR : NULL; |
| } |
| |
| if (const UnaryOperator *U = dyn_cast<UnaryOperator>(expr)) |
| return U->isIncrementDecrementOp() |
| ? getIncrementedVar(U->getSubExpr(), x, y) : NULL; |
| |
| return NULL; |
| } |
| |
| /// 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 : NULL; |
| drRHS = drRHS && drRHS->getType()->isRealFloatingType() ? drRHS : NULL; |
| |
| if (!drLHS && !drRHS) |
| return; |
| |
| const VarDecl *vdLHS = drLHS ? dyn_cast<VarDecl>(drLHS->getDecl()) : NULL; |
| const VarDecl *vdRHS = drRHS ? dyn_cast<VarDecl>(drRHS->getDecl()) : NULL; |
| |
| 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. |
| 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(bugType, "Security", os.str(), |
| FSLoc, ranges.data(), ranges.size()); |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // 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 |
| = dyn_cast<FunctionProtoType>(FD->getType().IgnoreParens()); |
| if (!FPT) |
| return; |
| |
| // Verify that the function takes a single argument. |
| if (FPT->getNumArgs() != 1) |
| return; |
| |
| // Is the argument a 'char*'? |
| const PointerType *PT = dyn_cast<PointerType>(FPT->getArgType(0)); |
| if (!PT) |
| return; |
| |
| if (PT->getPointeeType().getUnqualifiedType() != BR.getContext().CharTy) |
| return; |
| |
| // Issue a warning. |
| SourceRange R = CE->getCallee()->getSourceRange(); |
| PathDiagnosticLocation CELoc = |
| PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC); |
| BR.EmitBasicReport("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, &R, 1); |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // 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 |
| = dyn_cast<FunctionProtoType>(FD->getType().IgnoreParens()); |
| if (!FPT) |
| return; |
| |
| // Verify that the function takes two arguments. |
| if (FPT->getNumArgs() != 2) |
| return; |
| |
| // Verify the first argument type is integer. |
| if (!FPT->getArgType(0)->isIntegerType()) |
| return; |
| |
| // Verify the second argument type is char*. |
| const PointerType *PT = dyn_cast<PointerType>(FPT->getArgType(1)); |
| if (!PT) |
| return; |
| |
| if (PT->getPointeeType().getUnqualifiedType() != BR.getContext().CharTy) |
| return; |
| |
| // Issue a warning. |
| SourceRange R = CE->getCallee()->getSourceRange(); |
| PathDiagnosticLocation CELoc = |
| PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC); |
| BR.EmitBasicReport("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, &R, 1); |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // 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 |
| = dyn_cast<FunctionProtoType>(FD->getType().IgnoreParens()); |
| if(!FPT) |
| return; |
| |
| // Verify that the function takes a single argument. |
| if (FPT->getNumArgs() != 1) |
| return; |
| |
| // Verify that the argument is Pointer Type. |
| const PointerType *PT = dyn_cast<PointerType>(FPT->getArgType(0)); |
| if (!PT) |
| return; |
| |
| // Verify that the argument is a 'char*'. |
| if (PT->getPointeeType().getUnqualifiedType() != BR.getContext().CharTy) |
| return; |
| |
| // Issue a waring. |
| SourceRange R = CE->getCallee()->getSourceRange(); |
| PathDiagnosticLocation CELoc = |
| PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC); |
| BR.EmitBasicReport("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, &R, 1); |
| } |
| |
| |
| //===----------------------------------------------------------------------===// |
| // 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); |
| llvm::APSInt Result; |
| if (!suffixEx->EvaluateAsInt(Result, BR.getContext())) |
| return; |
| // 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. |
| SourceRange R = strArg->getSourceRange(); |
| 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("Insecure temporary file creation", "Security", |
| out.str(), CELoc, &R, 1); |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // 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; |
| |
| // Issue a warning. |
| SourceRange R = CE->getCallee()->getSourceRange(); |
| PathDiagnosticLocation CELoc = |
| PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC); |
| BR.EmitBasicReport("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, &R, 1); |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // 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. |
| SourceRange R = CE->getCallee()->getSourceRange(); |
| PathDiagnosticLocation CELoc = |
| PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC); |
| BR.EmitBasicReport("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, &R, 1); |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // Common check for str* functions with no bounds parameters. |
| //===----------------------------------------------------------------------===// |
| bool WalkAST::checkCall_strCommon(const CallExpr *CE, const FunctionDecl *FD) { |
| const FunctionProtoType *FPT |
| = dyn_cast<FunctionProtoType>(FD->getType().IgnoreParens()); |
| if (!FPT) |
| return false; |
| |
| // Verify the function takes two arguments, three in the _chk version. |
| int numArgs = FPT->getNumArgs(); |
| 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 = dyn_cast<PointerType>(FPT->getArgType(i)); |
| 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 |
| = dyn_cast<FunctionProtoType>(FD->getType().IgnoreParens()); |
| if (!FTP) |
| return; |
| |
| if (FTP->getNumArgs() == 1) { |
| // Is the argument an 'unsigned short *'? |
| // (Actually any integer type is allowed.) |
| const PointerType *PT = dyn_cast<PointerType>(FTP->getArgType(0)); |
| if (!PT) |
| return; |
| |
| if (! PT->getPointeeType()->isIntegerType()) |
| return; |
| } |
| else if (FTP->getNumArgs() != 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"; |
| |
| SourceRange R = CE->getCallee()->getSourceRange(); |
| PathDiagnosticLocation CELoc = |
| PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC); |
| BR.EmitBasicReport(os1.str(), "Security", os2.str(), CELoc, &R, 1); |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // 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 |
| = dyn_cast<FunctionProtoType>(FD->getType().IgnoreParens()); |
| if (!FTP) |
| return; |
| |
| // Verify that the function takes no argument. |
| if (FTP->getNumArgs() != 0) |
| return; |
| |
| // Issue a warning. |
| SourceRange R = CE->getCallee()->getSourceRange(); |
| PathDiagnosticLocation CELoc = |
| PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC); |
| BR.EmitBasicReport("'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, &R, 1); |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // 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. |
| SourceRange R = CE->getCallee()->getSourceRange(); |
| PathDiagnosticLocation CELoc = |
| PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC); |
| BR.EmitBasicReport("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, &R, 1); |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // 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] == NULL) { |
| 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 |
| = dyn_cast<FunctionProtoType>(FD->getType().IgnoreParens()); |
| if (!FTP) |
| return; |
| |
| // Verify that the function takes one or two arguments (depending on |
| // the function). |
| if (FTP->getNumArgs() != (identifierid < 4 ? 1 : 2)) |
| return; |
| |
| // The arguments must be integers. |
| for (unsigned i = 0; i < FTP->getNumArgs(); i++) |
| if (! FTP->getArgType(i)->isIntegerType()) |
| 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"; |
| |
| SourceRange R = CE->getCallee()->getSourceRange(); |
| PathDiagnosticLocation CELoc = |
| PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC); |
| BR.EmitBasicReport(os1.str(), "Security", os2.str(), CELoc, &R, 1); |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // 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()); |
| } |
| }; |
| } |
| |
| #define REGISTER_CHECKER(name) \ |
| void ento::register##name(CheckerManager &mgr) {\ |
| mgr.registerChecker<SecuritySyntaxChecker>()->filter.check_##name = true;\ |
| } |
| |
| 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) |
| |
| |