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Diffstat (limited to 'lib/Checker/CheckSecuritySyntaxOnly.cpp')
| -rw-r--r-- | lib/Checker/CheckSecuritySyntaxOnly.cpp | 494 |
1 files changed, 0 insertions, 494 deletions
diff --git a/lib/Checker/CheckSecuritySyntaxOnly.cpp b/lib/Checker/CheckSecuritySyntaxOnly.cpp deleted file mode 100644 index 9a2ac45fa2e1..000000000000 --- a/lib/Checker/CheckSecuritySyntaxOnly.cpp +++ /dev/null @@ -1,494 +0,0 @@ -//==- 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 "clang/Basic/TargetInfo.h" -#include "clang/Checker/BugReporter/BugReporter.h" -#include "clang/Checker/Checkers/LocalCheckers.h" -#include "clang/AST/StmtVisitor.h" -#include "llvm/Support/raw_ostream.h" - -using namespace clang; - -static bool isArc4RandomAvailable(const ASTContext &Ctx) { - const llvm::Triple &T = Ctx.Target.getTriple(); - return T.getVendor() == llvm::Triple::Apple || - T.getOS() == llvm::Triple::FreeBSD; -} - -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()->IgnoreParens()); - const DeclRefExpr *drRHS = dyn_cast<DeclRefExpr>(B->getRHS()->IgnoreParens()); - - // 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()); - 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()); - 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()); - 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()); - 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()); - 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()); - 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); -} - -//===----------------------------------------------------------------------===// -// Entry point for check. -//===----------------------------------------------------------------------===// - -void clang::CheckSecuritySyntaxOnly(const Decl *D, BugReporter &BR) { - WalkAST walker(BR); - walker.Visit(D->getBody()); -} |