From 39fcc9a984e2820e4ea0fa2ac4abd17d9f3a31df Mon Sep 17 00:00:00 2001
From: dim <dim@FreeBSD.org>
Date: Sun, 20 Feb 2011 13:06:31 +0000
Subject: Vendor import of clang trunk r126079:
http://llvm.org/svn/llvm-project/cfe/trunk@126079
---
.../Checkers/CheckSecuritySyntaxOnly.cpp | 517 +++++++++++++++++++++
1 file changed, 517 insertions(+)
create mode 100644 lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp
(limited to 'lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp')
diff --git a/lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp b/lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp
new file mode 100644
index 0000000..185520c
--- /dev/null
+++ b/lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp
@@ -0,0 +1,517 @@
+//==- 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/StaticAnalyzer/Core/CheckerV2.h"
+#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
+#include "clang/Basic/TargetInfo.h"
+#include "clang/AST/StmtVisitor.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace clang;
+using namespace ento;
+
+static bool isArc4RandomAvailable(const ASTContext &Ctx) {
+ const llvm::Triple &T = Ctx.Target.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 {
+class WalkAST : public StmtVisitor<WalkAST> {
+ BugReporter &BR;
+ IdentifierInfo *II_gets;
+ IdentifierInfo *II_getpw;
+ IdentifierInfo *II_mktemp;
+ enum { num_rands = 9 };
+ IdentifierInfo *II_rand[num_rands];
+ IdentifierInfo *II_random;
+ enum { num_setids = 6 };
+ IdentifierInfo *II_setid[num_setids];
+
+ const bool CheckRand;
+
+public:
+ WalkAST(BugReporter &br) : BR(br),
+ II_gets(0), II_getpw(0), II_mktemp(0),
+ II_rand(), II_random(0), II_setid(),
+ CheckRand(isArc4RandomAvailable(BR.getContext())) {}
+
+ // 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.
+ IdentifierInfo *GetIdentifier(IdentifierInfo *& II, const char *str);
+
+ // 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_rand(const CallExpr *CE, const FunctionDecl *FD);
+ void CheckCall_random(const CallExpr *CE, const FunctionDecl *FD);
+ void CheckUncheckedReturnValue(CallExpr *CE);
+};
+} // end anonymous namespace
+
+//===----------------------------------------------------------------------===//
+// Helper methods.
+//===----------------------------------------------------------------------===//
+
+IdentifierInfo *WalkAST::GetIdentifier(IdentifierInfo *& II, const char *str) {
+ if (!II)
+ II = &BR.getContext().Idents.get(str);
+
+ return II;
+}
+
+//===----------------------------------------------------------------------===//
+// 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) {
+ if (const FunctionDecl *FD = CE->getDirectCallee()) {
+ CheckCall_gets(CE, FD);
+ CheckCall_getpw(CE, FD);
+ CheckCall_mktemp(CE, FD);
+ if (CheckRand) {
+ CheckCall_rand(CE, FD);
+ CheckCall_random(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) {
+ // 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;
+
+ llvm::SmallVector<SourceRange, 2> ranges;
+ llvm::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";
+ BR.EmitBasicReport(bugType, "Security", os.str(),
+ FS->getLocStart(), 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 (FD->getIdentifier() != GetIdentifier(II_gets, "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();
+ 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",
+ CE->getLocStart(), &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 (FD->getIdentifier() != GetIdentifier(II_getpw, "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();
+ 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().",
+ CE->getLocStart(), &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 (FD->getIdentifier() != GetIdentifier(II_mktemp, "mktemp"))
+ return;
+
+ const FunctionProtoType *FPT
+ = dyn_cast<FunctionProtoType>(FD->getType().IgnoreParens());
+ if(!FPT)
+ return;
+
+ // Verify that the funcion 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();
+ 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",
+ CE->getLocStart(), &R, 1);
+}
+
+//===----------------------------------------------------------------------===//
+// 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 (II_rand[0] == NULL) {
+ // This check applies to these functions
+ static const char * const identifiers[num_rands] = {
+ "drand48", "erand48", "jrand48", "lrand48", "mrand48", "nrand48",
+ "lcong48",
+ "rand", "rand_r"
+ };
+
+ for (size_t i = 0; i < num_rands; i++)
+ II_rand[i] = &BR.getContext().Idents.get(identifiers[i]);
+ }
+
+ const IdentifierInfo *id = FD->getIdentifier();
+ size_t identifierid;
+
+ for (identifierid = 0; identifierid < num_rands; identifierid++)
+ if (id == II_rand[identifierid])
+ break;
+
+ if (identifierid >= num_rands)
+ 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.
+ llvm::SmallString<256> buf1;
+ llvm::raw_svector_ostream os1(buf1);
+ os1 << '\'' << FD << "' is a poor random number generator";
+
+ llvm::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();
+ BR.EmitBasicReport(os1.str(), "Security", os2.str(),CE->getLocStart(), &R, 1);
+}
+
+//===----------------------------------------------------------------------===//
+// Check: 'random' should not be used
+// Originally: <rdar://problem/63371000>
+//===----------------------------------------------------------------------===//
+
+void WalkAST::CheckCall_random(const CallExpr *CE, const FunctionDecl *FD) {
+ if (FD->getIdentifier() != GetIdentifier(II_random, "random"))
+ 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();
+ 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", CE->getLocStart(), &R, 1);
+}
+
+//===----------------------------------------------------------------------===//
+// Check: Should check whether privileges are dropped successfully.
+// Originally: <rdar://problem/6337132>
+//===----------------------------------------------------------------------===//
+
+void WalkAST::CheckUncheckedReturnValue(CallExpr *CE) {
+ 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.
+ llvm::SmallString<256> buf1;
+ llvm::raw_svector_ostream os1(buf1);
+ os1 << "Return value is not checked in call to '" << FD << '\'';
+
+ llvm::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();
+ BR.EmitBasicReport(os1.str(), "Security", os2.str(),CE->getLocStart(), &R, 1);
+}
+
+//===----------------------------------------------------------------------===//
+// SecuritySyntaxChecker
+//===----------------------------------------------------------------------===//
+
+namespace {
+class SecuritySyntaxChecker : public CheckerV2<check::ASTCodeBody> {
+public:
+ void checkASTCodeBody(const Decl *D, AnalysisManager& mgr,
+ BugReporter &BR) const {
+ WalkAST walker(BR);
+ walker.Visit(D->getBody());
+ }
+};
+}
+
+void ento::registerSecuritySyntaxChecker(CheckerManager &mgr) {
+ mgr.registerChecker<SecuritySyntaxChecker>();
+}
--
cgit v1.1