764 lines
26 KiB
C++
764 lines
26 KiB
C++
//==- CheckSecuritySyntaxOnly.cpp - Basic security checks --------*- C++ -*-==//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines a set of flow-insensitive security checks.
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//
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//===----------------------------------------------------------------------===//
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#include "ClangSACheckers.h"
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#include "clang/AST/StmtVisitor.h"
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#include "clang/Analysis/AnalysisContext.h"
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#include "clang/Basic/TargetInfo.h"
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#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
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#include "clang/StaticAnalyzer/Core/Checker.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h"
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#include "llvm/ADT/SmallString.h"
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#include "llvm/ADT/StringSwitch.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace clang;
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using namespace ento;
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static bool isArc4RandomAvailable(const ASTContext &Ctx) {
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const llvm::Triple &T = Ctx.getTargetInfo().getTriple();
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return T.getVendor() == llvm::Triple::Apple ||
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T.getOS() == llvm::Triple::FreeBSD ||
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T.getOS() == llvm::Triple::NetBSD ||
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T.getOS() == llvm::Triple::OpenBSD ||
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T.getOS() == llvm::Triple::Bitrig ||
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T.getOS() == llvm::Triple::DragonFly;
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}
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namespace {
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struct ChecksFilter {
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DefaultBool check_gets;
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DefaultBool check_getpw;
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DefaultBool check_mktemp;
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DefaultBool check_mkstemp;
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DefaultBool check_strcpy;
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DefaultBool check_rand;
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DefaultBool check_vfork;
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DefaultBool check_FloatLoopCounter;
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DefaultBool check_UncheckedReturn;
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};
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class WalkAST : public StmtVisitor<WalkAST> {
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BugReporter &BR;
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AnalysisDeclContext* AC;
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enum { num_setids = 6 };
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IdentifierInfo *II_setid[num_setids];
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const bool CheckRand;
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const ChecksFilter &filter;
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public:
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WalkAST(BugReporter &br, AnalysisDeclContext* ac,
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const ChecksFilter &f)
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: BR(br), AC(ac), II_setid(),
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CheckRand(isArc4RandomAvailable(BR.getContext())),
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filter(f) {}
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// Statement visitor methods.
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void VisitCallExpr(CallExpr *CE);
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void VisitForStmt(ForStmt *S);
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void VisitCompoundStmt (CompoundStmt *S);
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void VisitStmt(Stmt *S) { VisitChildren(S); }
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void VisitChildren(Stmt *S);
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// Helpers.
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bool checkCall_strCommon(const CallExpr *CE, const FunctionDecl *FD);
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typedef void (WalkAST::*FnCheck)(const CallExpr *,
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const FunctionDecl *);
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// Checker-specific methods.
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void checkLoopConditionForFloat(const ForStmt *FS);
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void checkCall_gets(const CallExpr *CE, const FunctionDecl *FD);
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void checkCall_getpw(const CallExpr *CE, const FunctionDecl *FD);
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void checkCall_mktemp(const CallExpr *CE, const FunctionDecl *FD);
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void checkCall_mkstemp(const CallExpr *CE, const FunctionDecl *FD);
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void checkCall_strcpy(const CallExpr *CE, const FunctionDecl *FD);
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void checkCall_strcat(const CallExpr *CE, const FunctionDecl *FD);
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void checkCall_rand(const CallExpr *CE, const FunctionDecl *FD);
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void checkCall_random(const CallExpr *CE, const FunctionDecl *FD);
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void checkCall_vfork(const CallExpr *CE, const FunctionDecl *FD);
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void checkUncheckedReturnValue(CallExpr *CE);
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};
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} // end anonymous namespace
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//===----------------------------------------------------------------------===//
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// AST walking.
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//===----------------------------------------------------------------------===//
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void WalkAST::VisitChildren(Stmt *S) {
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for (Stmt::child_iterator I = S->child_begin(), E = S->child_end(); I!=E; ++I)
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if (Stmt *child = *I)
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Visit(child);
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}
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void WalkAST::VisitCallExpr(CallExpr *CE) {
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// Get the callee.
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const FunctionDecl *FD = CE->getDirectCallee();
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if (!FD)
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return;
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// Get the name of the callee. If it's a builtin, strip off the prefix.
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IdentifierInfo *II = FD->getIdentifier();
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if (!II) // if no identifier, not a simple C function
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return;
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StringRef Name = II->getName();
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if (Name.startswith("__builtin_"))
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Name = Name.substr(10);
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// Set the evaluation function by switching on the callee name.
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FnCheck evalFunction = llvm::StringSwitch<FnCheck>(Name)
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.Case("gets", &WalkAST::checkCall_gets)
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.Case("getpw", &WalkAST::checkCall_getpw)
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.Case("mktemp", &WalkAST::checkCall_mktemp)
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.Case("mkstemp", &WalkAST::checkCall_mkstemp)
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.Case("mkdtemp", &WalkAST::checkCall_mkstemp)
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.Case("mkstemps", &WalkAST::checkCall_mkstemp)
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.Cases("strcpy", "__strcpy_chk", &WalkAST::checkCall_strcpy)
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.Cases("strcat", "__strcat_chk", &WalkAST::checkCall_strcat)
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.Case("drand48", &WalkAST::checkCall_rand)
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.Case("erand48", &WalkAST::checkCall_rand)
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.Case("jrand48", &WalkAST::checkCall_rand)
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.Case("lrand48", &WalkAST::checkCall_rand)
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.Case("mrand48", &WalkAST::checkCall_rand)
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.Case("nrand48", &WalkAST::checkCall_rand)
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.Case("lcong48", &WalkAST::checkCall_rand)
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.Case("rand", &WalkAST::checkCall_rand)
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.Case("rand_r", &WalkAST::checkCall_rand)
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.Case("random", &WalkAST::checkCall_random)
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.Case("vfork", &WalkAST::checkCall_vfork)
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.Default(NULL);
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// If the callee isn't defined, it is not of security concern.
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// Check and evaluate the call.
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if (evalFunction)
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(this->*evalFunction)(CE, FD);
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// Recurse and check children.
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VisitChildren(CE);
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}
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void WalkAST::VisitCompoundStmt(CompoundStmt *S) {
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for (Stmt::child_iterator I = S->child_begin(), E = S->child_end(); I!=E; ++I)
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if (Stmt *child = *I) {
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if (CallExpr *CE = dyn_cast<CallExpr>(child))
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checkUncheckedReturnValue(CE);
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Visit(child);
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}
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}
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void WalkAST::VisitForStmt(ForStmt *FS) {
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checkLoopConditionForFloat(FS);
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// Recurse and check children.
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VisitChildren(FS);
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}
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//===----------------------------------------------------------------------===//
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// Check: floating poing variable used as loop counter.
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// Originally: <rdar://problem/6336718>
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// Implements: CERT security coding advisory FLP-30.
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//===----------------------------------------------------------------------===//
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static const DeclRefExpr*
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getIncrementedVar(const Expr *expr, const VarDecl *x, const VarDecl *y) {
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expr = expr->IgnoreParenCasts();
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if (const BinaryOperator *B = dyn_cast<BinaryOperator>(expr)) {
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if (!(B->isAssignmentOp() || B->isCompoundAssignmentOp() ||
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B->getOpcode() == BO_Comma))
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return NULL;
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if (const DeclRefExpr *lhs = getIncrementedVar(B->getLHS(), x, y))
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return lhs;
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if (const DeclRefExpr *rhs = getIncrementedVar(B->getRHS(), x, y))
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return rhs;
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return NULL;
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}
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if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(expr)) {
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const NamedDecl *ND = DR->getDecl();
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return ND == x || ND == y ? DR : NULL;
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}
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if (const UnaryOperator *U = dyn_cast<UnaryOperator>(expr))
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return U->isIncrementDecrementOp()
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? getIncrementedVar(U->getSubExpr(), x, y) : NULL;
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return NULL;
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}
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/// CheckLoopConditionForFloat - This check looks for 'for' statements that
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/// use a floating point variable as a loop counter.
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/// CERT: FLP30-C, FLP30-CPP.
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///
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void WalkAST::checkLoopConditionForFloat(const ForStmt *FS) {
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if (!filter.check_FloatLoopCounter)
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return;
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// Does the loop have a condition?
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const Expr *condition = FS->getCond();
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if (!condition)
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return;
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// Does the loop have an increment?
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const Expr *increment = FS->getInc();
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if (!increment)
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return;
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// Strip away '()' and casts.
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condition = condition->IgnoreParenCasts();
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increment = increment->IgnoreParenCasts();
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// Is the loop condition a comparison?
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const BinaryOperator *B = dyn_cast<BinaryOperator>(condition);
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if (!B)
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return;
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// Is this a comparison?
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if (!(B->isRelationalOp() || B->isEqualityOp()))
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return;
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// Are we comparing variables?
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const DeclRefExpr *drLHS =
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dyn_cast<DeclRefExpr>(B->getLHS()->IgnoreParenLValueCasts());
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const DeclRefExpr *drRHS =
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dyn_cast<DeclRefExpr>(B->getRHS()->IgnoreParenLValueCasts());
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// Does at least one of the variables have a floating point type?
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drLHS = drLHS && drLHS->getType()->isRealFloatingType() ? drLHS : NULL;
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drRHS = drRHS && drRHS->getType()->isRealFloatingType() ? drRHS : NULL;
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if (!drLHS && !drRHS)
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return;
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const VarDecl *vdLHS = drLHS ? dyn_cast<VarDecl>(drLHS->getDecl()) : NULL;
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const VarDecl *vdRHS = drRHS ? dyn_cast<VarDecl>(drRHS->getDecl()) : NULL;
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if (!vdLHS && !vdRHS)
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return;
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// Does either variable appear in increment?
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const DeclRefExpr *drInc = getIncrementedVar(increment, vdLHS, vdRHS);
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if (!drInc)
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return;
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// Emit the error. First figure out which DeclRefExpr in the condition
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// referenced the compared variable.
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assert(drInc->getDecl());
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const DeclRefExpr *drCond = vdLHS == drInc->getDecl() ? drLHS : drRHS;
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SmallVector<SourceRange, 2> ranges;
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SmallString<256> sbuf;
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llvm::raw_svector_ostream os(sbuf);
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os << "Variable '" << drCond->getDecl()->getName()
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<< "' with floating point type '" << drCond->getType().getAsString()
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<< "' should not be used as a loop counter";
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ranges.push_back(drCond->getSourceRange());
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ranges.push_back(drInc->getSourceRange());
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const char *bugType = "Floating point variable used as loop counter";
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PathDiagnosticLocation FSLoc =
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PathDiagnosticLocation::createBegin(FS, BR.getSourceManager(), AC);
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BR.EmitBasicReport(AC->getDecl(),
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bugType, "Security", os.str(),
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FSLoc, ranges);
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}
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//===----------------------------------------------------------------------===//
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// Check: Any use of 'gets' is insecure.
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// Originally: <rdar://problem/6335715>
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// Implements (part of): 300-BSI (buildsecurityin.us-cert.gov)
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// CWE-242: Use of Inherently Dangerous Function
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//===----------------------------------------------------------------------===//
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void WalkAST::checkCall_gets(const CallExpr *CE, const FunctionDecl *FD) {
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if (!filter.check_gets)
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return;
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const FunctionProtoType *FPT = FD->getType()->getAs<FunctionProtoType>();
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if (!FPT)
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return;
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// Verify that the function takes a single argument.
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if (FPT->getNumArgs() != 1)
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return;
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// Is the argument a 'char*'?
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const PointerType *PT = FPT->getArgType(0)->getAs<PointerType>();
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if (!PT)
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return;
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if (PT->getPointeeType().getUnqualifiedType() != BR.getContext().CharTy)
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return;
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// Issue a warning.
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PathDiagnosticLocation CELoc =
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PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
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BR.EmitBasicReport(AC->getDecl(),
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"Potential buffer overflow in call to 'gets'",
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"Security",
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"Call to function 'gets' is extremely insecure as it can "
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"always result in a buffer overflow",
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CELoc, CE->getCallee()->getSourceRange());
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}
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//===----------------------------------------------------------------------===//
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// Check: Any use of 'getpwd' is insecure.
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// CWE-477: Use of Obsolete Functions
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//===----------------------------------------------------------------------===//
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void WalkAST::checkCall_getpw(const CallExpr *CE, const FunctionDecl *FD) {
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if (!filter.check_getpw)
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return;
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const FunctionProtoType *FPT = FD->getType()->getAs<FunctionProtoType>();
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if (!FPT)
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return;
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// Verify that the function takes two arguments.
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if (FPT->getNumArgs() != 2)
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return;
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// Verify the first argument type is integer.
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if (!FPT->getArgType(0)->isIntegralOrUnscopedEnumerationType())
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return;
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// Verify the second argument type is char*.
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const PointerType *PT = FPT->getArgType(1)->getAs<PointerType>();
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if (!PT)
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return;
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if (PT->getPointeeType().getUnqualifiedType() != BR.getContext().CharTy)
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return;
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// Issue a warning.
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PathDiagnosticLocation CELoc =
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PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
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BR.EmitBasicReport(AC->getDecl(),
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"Potential buffer overflow in call to 'getpw'",
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"Security",
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"The getpw() function is dangerous as it may overflow the "
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"provided buffer. It is obsoleted by getpwuid().",
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CELoc, CE->getCallee()->getSourceRange());
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}
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//===----------------------------------------------------------------------===//
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// Check: Any use of 'mktemp' is insecure. It is obsoleted by mkstemp().
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// CWE-377: Insecure Temporary File
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//===----------------------------------------------------------------------===//
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void WalkAST::checkCall_mktemp(const CallExpr *CE, const FunctionDecl *FD) {
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if (!filter.check_mktemp) {
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// Fall back to the security check of looking for enough 'X's in the
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// format string, since that is a less severe warning.
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checkCall_mkstemp(CE, FD);
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return;
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}
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const FunctionProtoType *FPT = FD->getType()->getAs<FunctionProtoType>();
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if(!FPT)
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return;
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// Verify that the function takes a single argument.
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if (FPT->getNumArgs() != 1)
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return;
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// Verify that the argument is Pointer Type.
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const PointerType *PT = FPT->getArgType(0)->getAs<PointerType>();
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if (!PT)
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return;
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// Verify that the argument is a 'char*'.
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if (PT->getPointeeType().getUnqualifiedType() != BR.getContext().CharTy)
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return;
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// Issue a waring.
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PathDiagnosticLocation CELoc =
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PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
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BR.EmitBasicReport(AC->getDecl(),
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"Potential insecure temporary file in call 'mktemp'",
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"Security",
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"Call to function 'mktemp' is insecure as it always "
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"creates or uses insecure temporary file. Use 'mkstemp' "
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"instead",
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CELoc, CE->getCallee()->getSourceRange());
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}
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//===----------------------------------------------------------------------===//
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// Check: Use of 'mkstemp', 'mktemp', 'mkdtemp' should contain at least 6 X's.
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//===----------------------------------------------------------------------===//
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void WalkAST::checkCall_mkstemp(const CallExpr *CE, const FunctionDecl *FD) {
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if (!filter.check_mkstemp)
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return;
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StringRef Name = FD->getIdentifier()->getName();
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std::pair<signed, signed> ArgSuffix =
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llvm::StringSwitch<std::pair<signed, signed> >(Name)
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.Case("mktemp", std::make_pair(0,-1))
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.Case("mkstemp", std::make_pair(0,-1))
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.Case("mkdtemp", std::make_pair(0,-1))
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.Case("mkstemps", std::make_pair(0,1))
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.Default(std::make_pair(-1, -1));
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assert(ArgSuffix.first >= 0 && "Unsupported function");
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// Check if the number of arguments is consistent with out expectations.
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unsigned numArgs = CE->getNumArgs();
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if ((signed) numArgs <= ArgSuffix.first)
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return;
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const StringLiteral *strArg =
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dyn_cast<StringLiteral>(CE->getArg((unsigned)ArgSuffix.first)
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->IgnoreParenImpCasts());
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// Currently we only handle string literals. It is possible to do better,
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// either by looking at references to const variables, or by doing real
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// flow analysis.
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if (!strArg || strArg->getCharByteWidth() != 1)
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return;
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// Count the number of X's, taking into account a possible cutoff suffix.
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StringRef str = strArg->getString();
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unsigned numX = 0;
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unsigned n = str.size();
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// Take into account the suffix.
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unsigned suffix = 0;
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if (ArgSuffix.second >= 0) {
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const Expr *suffixEx = CE->getArg((unsigned)ArgSuffix.second);
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llvm::APSInt Result;
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if (!suffixEx->EvaluateAsInt(Result, BR.getContext()))
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return;
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// FIXME: Issue a warning.
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if (Result.isNegative())
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return;
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suffix = (unsigned) Result.getZExtValue();
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n = (n > suffix) ? n - suffix : 0;
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}
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for (unsigned i = 0; i < n; ++i)
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if (str[i] == 'X') ++numX;
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if (numX >= 6)
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return;
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// Issue a warning.
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PathDiagnosticLocation CELoc =
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PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
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SmallString<512> buf;
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llvm::raw_svector_ostream out(buf);
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out << "Call to '" << Name << "' should have at least 6 'X's in the"
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" format string to be secure (" << numX << " 'X'";
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if (numX != 1)
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out << 's';
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out << " seen";
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if (suffix) {
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out << ", " << suffix << " character";
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if (suffix > 1)
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out << 's';
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out << " used as a suffix";
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}
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out << ')';
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BR.EmitBasicReport(AC->getDecl(),
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"Insecure temporary file creation", "Security",
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out.str(), CELoc, strArg->getSourceRange());
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}
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//===----------------------------------------------------------------------===//
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// Check: Any use of 'strcpy' is insecure.
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//
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// CWE-119: Improper Restriction of Operations within
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// the Bounds of a Memory Buffer
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//===----------------------------------------------------------------------===//
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void WalkAST::checkCall_strcpy(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(),
|
|
"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(),
|
|
"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());
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// 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->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 = FPT->getArgType(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->getNumArgs() == 1) {
|
|
// Is the argument an 'unsigned short *'?
|
|
// (Actually any integer type is allowed.)
|
|
const PointerType *PT = FTP->getArgType(0)->getAs<PointerType>();
|
|
if (!PT)
|
|
return;
|
|
|
|
if (! PT->getPointeeType()->isIntegralOrUnscopedEnumerationType())
|
|
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";
|
|
|
|
PathDiagnosticLocation CELoc =
|
|
PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
|
|
BR.EmitBasicReport(AC->getDecl(), 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->getNumArgs() != 0)
|
|
return;
|
|
|
|
// Issue a warning.
|
|
PathDiagnosticLocation CELoc =
|
|
PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
|
|
BR.EmitBasicReport(AC->getDecl(),
|
|
"'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(),
|
|
"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] == 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 = FD->getType()->getAs<FunctionProtoType>();
|
|
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)->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(), 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());
|
|
}
|
|
};
|
|
}
|
|
|
|
#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)
|
|
|
|
|