From 222e2a7620e6520ffaf4fc4e69d79c18da31542e Mon Sep 17 00:00:00 2001 From: "Zancanaro; Carlo" Date: Mon, 24 Sep 2012 09:58:17 +1000 Subject: Add the clang library to the repo (with some of my changes, too). --- .../lib/StaticAnalyzer/Checkers/ChrootChecker.cpp | 158 +++++++++++++++++++++ 1 file changed, 158 insertions(+) create mode 100644 clang/lib/StaticAnalyzer/Checkers/ChrootChecker.cpp (limited to 'clang/lib/StaticAnalyzer/Checkers/ChrootChecker.cpp') diff --git a/clang/lib/StaticAnalyzer/Checkers/ChrootChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/ChrootChecker.cpp new file mode 100644 index 0000000..30d0609 --- /dev/null +++ b/clang/lib/StaticAnalyzer/Checkers/ChrootChecker.cpp @@ -0,0 +1,158 @@ +//===- Chrootchecker.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 chroot checker, which checks improper use of chroot. +// +//===----------------------------------------------------------------------===// + +#include "ClangSACheckers.h" +#include "clang/StaticAnalyzer/Core/Checker.h" +#include "clang/StaticAnalyzer/Core/CheckerManager.h" +#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" +#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h" +#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h" +#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h" +#include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h" +#include "llvm/ADT/ImmutableMap.h" +using namespace clang; +using namespace ento; + +namespace { + +// enum value that represent the jail state +enum Kind { NO_CHROOT, ROOT_CHANGED, JAIL_ENTERED }; + +bool isRootChanged(intptr_t k) { return k == ROOT_CHANGED; } +//bool isJailEntered(intptr_t k) { return k == JAIL_ENTERED; } + +// This checker checks improper use of chroot. +// The state transition: +// NO_CHROOT ---chroot(path)--> ROOT_CHANGED ---chdir(/) --> JAIL_ENTERED +// | | +// ROOT_CHANGED<--chdir(..)-- JAIL_ENTERED<--chdir(..)-- +// | | +// bug<--foo()-- JAIL_ENTERED<--foo()-- +class ChrootChecker : public Checker > { + mutable IdentifierInfo *II_chroot, *II_chdir; + // This bug refers to possibly break out of a chroot() jail. + mutable OwningPtr BT_BreakJail; + +public: + ChrootChecker() : II_chroot(0), II_chdir(0) {} + + static void *getTag() { + static int x; + return &x; + } + + bool evalCall(const CallExpr *CE, CheckerContext &C) const; + void checkPreStmt(const CallExpr *CE, CheckerContext &C) const; + +private: + void Chroot(CheckerContext &C, const CallExpr *CE) const; + void Chdir(CheckerContext &C, const CallExpr *CE) const; +}; + +} // end anonymous namespace + +bool ChrootChecker::evalCall(const CallExpr *CE, CheckerContext &C) const { + const FunctionDecl *FD = C.getCalleeDecl(CE); + if (!FD) + return false; + + ASTContext &Ctx = C.getASTContext(); + if (!II_chroot) + II_chroot = &Ctx.Idents.get("chroot"); + if (!II_chdir) + II_chdir = &Ctx.Idents.get("chdir"); + + if (FD->getIdentifier() == II_chroot) { + Chroot(C, CE); + return true; + } + if (FD->getIdentifier() == II_chdir) { + Chdir(C, CE); + return true; + } + + return false; +} + +void ChrootChecker::Chroot(CheckerContext &C, const CallExpr *CE) const { + ProgramStateRef state = C.getState(); + ProgramStateManager &Mgr = state->getStateManager(); + + // Once encouter a chroot(), set the enum value ROOT_CHANGED directly in + // the GDM. + state = Mgr.addGDM(state, ChrootChecker::getTag(), (void*) ROOT_CHANGED); + C.addTransition(state); +} + +void ChrootChecker::Chdir(CheckerContext &C, const CallExpr *CE) const { + ProgramStateRef state = C.getState(); + ProgramStateManager &Mgr = state->getStateManager(); + + // If there are no jail state in the GDM, just return. + const void *k = state->FindGDM(ChrootChecker::getTag()); + if (!k) + return; + + // After chdir("/"), enter the jail, set the enum value JAIL_ENTERED. + const Expr *ArgExpr = CE->getArg(0); + SVal ArgVal = state->getSVal(ArgExpr, C.getLocationContext()); + + if (const MemRegion *R = ArgVal.getAsRegion()) { + R = R->StripCasts(); + if (const StringRegion* StrRegion= dyn_cast(R)) { + const StringLiteral* Str = StrRegion->getStringLiteral(); + if (Str->getString() == "/") + state = Mgr.addGDM(state, ChrootChecker::getTag(), + (void*) JAIL_ENTERED); + } + } + + C.addTransition(state); +} + +// Check the jail state before any function call except chroot and chdir(). +void ChrootChecker::checkPreStmt(const CallExpr *CE, CheckerContext &C) const { + const FunctionDecl *FD = C.getCalleeDecl(CE); + if (!FD) + return; + + ASTContext &Ctx = C.getASTContext(); + if (!II_chroot) + II_chroot = &Ctx.Idents.get("chroot"); + if (!II_chdir) + II_chdir = &Ctx.Idents.get("chdir"); + + // Ingnore chroot and chdir. + if (FD->getIdentifier() == II_chroot || FD->getIdentifier() == II_chdir) + return; + + // If jail state is ROOT_CHANGED, generate BugReport. + void *const* k = C.getState()->FindGDM(ChrootChecker::getTag()); + if (k) + if (isRootChanged((intptr_t) *k)) + if (ExplodedNode *N = C.addTransition()) { + if (!BT_BreakJail) + BT_BreakJail.reset(new BuiltinBug("Break out of jail", + "No call of chdir(\"/\") immediately " + "after chroot")); + BugReport *R = new BugReport(*BT_BreakJail, + BT_BreakJail->getDescription(), N); + C.EmitReport(R); + } + + return; +} + +void ento::registerChrootChecker(CheckerManager &mgr) { + mgr.registerChecker(); +} -- cgit v1.2.3