Update from chromium 62675d9fb31fb8cedc40f68e78e8445a74f362e7

sandbox/linux/bpf_dsl/bpf_dsl.cc

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "sandbox/linux/bpf_dsl/bpf_dsl.h"
+
+#include <errno.h>
+
+#include <limits>
+
+#include "base/logging.h"
+#include "base/memory/ref_counted.h"
+#include "sandbox/linux/bpf_dsl/bpf_dsl_impl.h"
+#include "sandbox/linux/bpf_dsl/policy_compiler.h"
+#include "sandbox/linux/seccomp-bpf/errorcode.h"
+
+namespace sandbox {
+namespace bpf_dsl {
+namespace {
+
+class AllowResultExprImpl : public internal::ResultExprImpl {
+ public:
+  AllowResultExprImpl() {}
+
+  virtual ErrorCode Compile(PolicyCompiler* pc) const override {
+    return ErrorCode(ErrorCode::ERR_ALLOWED);
+  }
+
+ private:
+  virtual ~AllowResultExprImpl() {}
+
+  DISALLOW_COPY_AND_ASSIGN(AllowResultExprImpl);
+};
+
+class ErrorResultExprImpl : public internal::ResultExprImpl {
+ public:
+  explicit ErrorResultExprImpl(int err) : err_(err) {
+    CHECK(err_ >= ErrorCode::ERR_MIN_ERRNO && err_ <= ErrorCode::ERR_MAX_ERRNO);
+  }
+
+  virtual ErrorCode Compile(PolicyCompiler* pc) const override {
+    return pc->Error(err_);
+  }
+
+ private:
+  virtual ~ErrorResultExprImpl() {}
+
+  int err_;
+
+  DISALLOW_COPY_AND_ASSIGN(ErrorResultExprImpl);
+};
+
+class KillResultExprImpl : public internal::ResultExprImpl {
+ public:
+  explicit KillResultExprImpl(const char* msg) : msg_(msg) { DCHECK(msg_); }
+
+  virtual ErrorCode Compile(PolicyCompiler* pc) const override {
+    return pc->Kill(msg_);
+  }
+
+ private:
+  virtual ~KillResultExprImpl() {}
+
+  const char* msg_;
+
+  DISALLOW_COPY_AND_ASSIGN(KillResultExprImpl);
+};
+
+class TraceResultExprImpl : public internal::ResultExprImpl {
+ public:
+  TraceResultExprImpl(uint16_t aux) : aux_(aux) {}
+
+  virtual ErrorCode Compile(PolicyCompiler* pc) const override {
+    return ErrorCode(ErrorCode::ERR_TRACE + aux_);
+  }
+
+ private:
+  virtual ~TraceResultExprImpl() {}
+
+  uint16_t aux_;
+
+  DISALLOW_COPY_AND_ASSIGN(TraceResultExprImpl);
+};
+
+class TrapResultExprImpl : public internal::ResultExprImpl {
+ public:
+  TrapResultExprImpl(TrapRegistry::TrapFnc func, const void* arg)
+      : func_(func), arg_(arg) {
+    DCHECK(func_);
+  }
+
+  virtual ErrorCode Compile(PolicyCompiler* pc) const override {
+    return pc->Trap(func_, arg_);
+  }
+
+ private:
+  virtual ~TrapResultExprImpl() {}
+
+  TrapRegistry::TrapFnc func_;
+  const void* arg_;
+
+  DISALLOW_COPY_AND_ASSIGN(TrapResultExprImpl);
+};
+
+class UnsafeTrapResultExprImpl : public internal::ResultExprImpl {
+ public:
+  UnsafeTrapResultExprImpl(TrapRegistry::TrapFnc func, const void* arg)
+      : func_(func), arg_(arg) {
+    DCHECK(func_);
+  }
+
+  virtual ErrorCode Compile(PolicyCompiler* pc) const override {
+    return pc->UnsafeTrap(func_, arg_);
+  }
+
+  virtual bool HasUnsafeTraps() const override { return true; }
+
+ private:
+  virtual ~UnsafeTrapResultExprImpl() {}
+
+  TrapRegistry::TrapFnc func_;
+  const void* arg_;
+
+  DISALLOW_COPY_AND_ASSIGN(UnsafeTrapResultExprImpl);
+};
+
+class IfThenResultExprImpl : public internal::ResultExprImpl {
+ public:
+  IfThenResultExprImpl(const BoolExpr& cond,
+                       const ResultExpr& then_result,
+                       const ResultExpr& else_result)
+      : cond_(cond), then_result_(then_result), else_result_(else_result) {}
+
+  virtual ErrorCode Compile(PolicyCompiler* pc) const override {
+    return cond_->Compile(
+        pc, then_result_->Compile(pc), else_result_->Compile(pc));
+  }
+
+  virtual bool HasUnsafeTraps() const override {
+    return then_result_->HasUnsafeTraps() || else_result_->HasUnsafeTraps();
+  }
+
+ private:
+  virtual ~IfThenResultExprImpl() {}
+
+  BoolExpr cond_;
+  ResultExpr then_result_;
+  ResultExpr else_result_;
+
+  DISALLOW_COPY_AND_ASSIGN(IfThenResultExprImpl);
+};
+
+class ConstBoolExprImpl : public internal::BoolExprImpl {
+ public:
+  ConstBoolExprImpl(bool value) : value_(value) {}
+
+  virtual ErrorCode Compile(PolicyCompiler* pc,
+                            ErrorCode true_ec,
+                            ErrorCode false_ec) const override {
+    return value_ ? true_ec : false_ec;
+  }
+
+ private:
+  virtual ~ConstBoolExprImpl() {}
+
+  bool value_;
+
+  DISALLOW_COPY_AND_ASSIGN(ConstBoolExprImpl);
+};
+
+class PrimitiveBoolExprImpl : public internal::BoolExprImpl {
+ public:
+  PrimitiveBoolExprImpl(int argno,
+                        ErrorCode::ArgType is_32bit,
+                        uint64_t mask,
+                        uint64_t value)
+      : argno_(argno), is_32bit_(is_32bit), mask_(mask), value_(value) {}
+
+  virtual ErrorCode Compile(PolicyCompiler* pc,
+                            ErrorCode true_ec,
+                            ErrorCode false_ec) const override {
+    return pc->CondMaskedEqual(
+        argno_, is_32bit_, mask_, value_, true_ec, false_ec);
+  }
+
+ private:
+  virtual ~PrimitiveBoolExprImpl() {}
+
+  int argno_;
+  ErrorCode::ArgType is_32bit_;
+  uint64_t mask_;
+  uint64_t value_;
+
+  DISALLOW_COPY_AND_ASSIGN(PrimitiveBoolExprImpl);
+};
+
+class NegateBoolExprImpl : public internal::BoolExprImpl {
+ public:
+  explicit NegateBoolExprImpl(const BoolExpr& cond) : cond_(cond) {}
+
+  virtual ErrorCode Compile(PolicyCompiler* pc,
+                            ErrorCode true_ec,
+                            ErrorCode false_ec) const override {
+    return cond_->Compile(pc, false_ec, true_ec);
+  }
+
+ private:
+  virtual ~NegateBoolExprImpl() {}
+
+  BoolExpr cond_;
+
+  DISALLOW_COPY_AND_ASSIGN(NegateBoolExprImpl);
+};
+
+class AndBoolExprImpl : public internal::BoolExprImpl {
+ public:
+  AndBoolExprImpl(const BoolExpr& lhs, const BoolExpr& rhs)
+      : lhs_(lhs), rhs_(rhs) {}
+
+  virtual ErrorCode Compile(PolicyCompiler* pc,
+                            ErrorCode true_ec,
+                            ErrorCode false_ec) const override {
+    return lhs_->Compile(pc, rhs_->Compile(pc, true_ec, false_ec), false_ec);
+  }
+
+ private:
+  virtual ~AndBoolExprImpl() {}
+
+  BoolExpr lhs_;
+  BoolExpr rhs_;
+
+  DISALLOW_COPY_AND_ASSIGN(AndBoolExprImpl);
+};
+
+class OrBoolExprImpl : public internal::BoolExprImpl {
+ public:
+  OrBoolExprImpl(const BoolExpr& lhs, const BoolExpr& rhs)
+      : lhs_(lhs), rhs_(rhs) {}
+
+  virtual ErrorCode Compile(PolicyCompiler* pc,
+                            ErrorCode true_ec,
+                            ErrorCode false_ec) const override {
+    return lhs_->Compile(pc, true_ec, rhs_->Compile(pc, true_ec, false_ec));
+  }
+
+ private:
+  virtual ~OrBoolExprImpl() {}
+
+  BoolExpr lhs_;
+  BoolExpr rhs_;
+
+  DISALLOW_COPY_AND_ASSIGN(OrBoolExprImpl);
+};
+
+}  // namespace
+
+namespace internal {
+
+bool ResultExprImpl::HasUnsafeTraps() const {
+  return false;
+}
+
+uint64_t DefaultMask(size_t size) {
+  switch (size) {
+    case 4:
+      return std::numeric_limits<uint32_t>::max();
+    case 8:
+      return std::numeric_limits<uint64_t>::max();
+    default:
+      CHECK(false) << "Unimplemented DefaultMask case";
+      return 0;
+  }
+}
+
+BoolExpr ArgEq(int num, size_t size, uint64_t mask, uint64_t val) {
+  CHECK(size == 4 || size == 8);
+
+  // TODO(mdempsky): Should we just always use TP_64BIT?
+  const ErrorCode::ArgType arg_type =
+      (size == 4) ? ErrorCode::TP_32BIT : ErrorCode::TP_64BIT;
+
+  return BoolExpr(new const PrimitiveBoolExprImpl(num, arg_type, mask, val));
+}
+
+}  // namespace internal
+
+ResultExpr Allow() {
+  return ResultExpr(new const AllowResultExprImpl());
+}
+
+ResultExpr Error(int err) {
+  return ResultExpr(new const ErrorResultExprImpl(err));
+}
+
+ResultExpr Kill(const char* msg) {
+  return ResultExpr(new const KillResultExprImpl(msg));
+}
+
+ResultExpr Trace(uint16_t aux) {
+  return ResultExpr(new const TraceResultExprImpl(aux));
+}
+
+ResultExpr Trap(TrapRegistry::TrapFnc trap_func, const void* aux) {
+  return ResultExpr(new const TrapResultExprImpl(trap_func, aux));
+}
+
+ResultExpr UnsafeTrap(TrapRegistry::TrapFnc trap_func, const void* aux) {
+  return ResultExpr(new const UnsafeTrapResultExprImpl(trap_func, aux));
+}
+
+BoolExpr BoolConst(bool value) {
+  return BoolExpr(new const ConstBoolExprImpl(value));
+}
+
+BoolExpr operator!(const BoolExpr& cond) {
+  return BoolExpr(new const NegateBoolExprImpl(cond));
+}
+
+BoolExpr operator&&(const BoolExpr& lhs, const BoolExpr& rhs) {
+  return BoolExpr(new const AndBoolExprImpl(lhs, rhs));
+}
+
+BoolExpr operator||(const BoolExpr& lhs, const BoolExpr& rhs) {
+  return BoolExpr(new const OrBoolExprImpl(lhs, rhs));
+}
+
+Elser If(const BoolExpr& cond, const ResultExpr& then_result) {
+  return Elser(nullptr).ElseIf(cond, then_result);
+}
+
+Elser::Elser(cons::List<Clause> clause_list) : clause_list_(clause_list) {
+}
+
+Elser::Elser(const Elser& elser) : clause_list_(elser.clause_list_) {
+}
+
+Elser::~Elser() {
+}
+
+Elser Elser::ElseIf(const BoolExpr& cond, const ResultExpr& then_result) const {
+  return Elser(Cons(std::make_pair(cond, then_result), clause_list_));
+}
+
+ResultExpr Elser::Else(const ResultExpr& else_result) const {
+  // We finally have the default result expression for this
+  // if/then/else sequence.  Also, we've already accumulated all
+  // if/then pairs into a list of reverse order (i.e., lower priority
+  // conditions are listed before higher priority ones).  E.g., an
+  // expression like
+  //
+  //    If(b1, e1).ElseIf(b2, e2).ElseIf(b3, e3).Else(e4)
+  //
+  // will have built up a list like
+  //
+  //    [(b3, e3), (b2, e2), (b1, e1)].
+  //
+  // Now that we have e4, we can walk the list and create a ResultExpr
+  // tree like:
+  //
+  //    expr = e4
+  //    expr = (b3 ? e3 : expr) = (b3 ? e3 : e4)
+  //    expr = (b2 ? e2 : expr) = (b2 ? e2 : (b3 ? e3 : e4))
+  //    expr = (b1 ? e1 : expr) = (b1 ? e1 : (b2 ? e2 : (b3 ? e3 : e4)))
+  //
+  // and end up with an appropriately chained tree.
+
+  ResultExpr expr = else_result;
+  for (const Clause& clause : clause_list_) {
+    expr = ResultExpr(
+        new const IfThenResultExprImpl(clause.first, clause.second, expr));
+  }
+  return expr;
+}
+
+ResultExpr SandboxBPFDSLPolicy::InvalidSyscall() const {
+  return Error(ENOSYS);
+}
+
+ResultExpr SandboxBPFDSLPolicy::Trap(TrapRegistry::TrapFnc trap_func,
+                                     const void* aux) {
+  return bpf_dsl::Trap(trap_func, aux);
+}
+
+}  // namespace bpf_dsl
+}  // namespace sandbox
+
+template class scoped_refptr<const sandbox::bpf_dsl::internal::BoolExprImpl>;
+template class scoped_refptr<const sandbox::bpf_dsl::internal::ResultExprImpl>;