Linux sandbox: migrate policies to new format.

seccomp-bpf policies are now the implementation of the interface that
lives in sandbox/linux/seccomp-bpf/sandbox_bpf_policy.h

Sandbox policies inside content/ will all derive from the SandboxBpfBasePolicy
(sandbox_bpf_base_policy.h) class.

We can now rely on real C++ inheritance to implement our policy hierarchy.

This is a first CL, part of a larger refactor. It should help minmize the risk
of error and facilitate review by keeping the general layout of the code similar.

In upcoming changes, we will:
1. Migrate NaCl and get rid of the compatibility / deprecated interfaces.
2. Extend the interface of SandboxBpfBasePolicy to be compatible with
starting a GPU sandbox and reflect all the steps.
3. Move all the policies to directories such as renderer/ and gpu/ and each
policy class will be able to live in its own file.

BUG=325535
R=creis@chromium.org, jorgelo@chromium.org, mseaborn@chromium.org, rsesek@chromium.org

Review URL: https://codereview.chromium.org/105673005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239550 0039d316-1c4b-4281-b951-d872f2087c98

components/nacl.gyp

@@ -188,6 +188,7 @@
                 'nacl/loader/nacl_helper_linux.h',
                 '../base/posix/unix_domain_socket_linux.cc',
                 '../content/common/child_process_sandbox_support_impl_shm_linux.cc',
+                '../content/common/sandbox_bpf_base_policy_linux.cc',
                 '../content/common/sandbox_init_linux.cc',
                 '../content/common/sandbox_seccomp_bpf_linux.cc',
                 '../content/public/common/content_switches.cc',

content/common/sandbox_bpf_base_policy_linux.cc

@@ -0,0 +1,36 @@
+// Copyright 2013 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 "content/common/sandbox_bpf_base_policy_linux.h"
+
+#include <errno.h>
+
+#include "base/logging.h"
+#include "sandbox/linux/seccomp-bpf-helpers/baseline_policy.h"
+
+namespace content {
+
+namespace {
+
+// The errno used for denied file system access system calls, such as open(2).
+static const int kFSDeniedErrno = EPERM;
+
+}  // namespace.
+
+SandboxBpfBasePolicy::SandboxBpfBasePolicy()
+    : baseline_policy_(new sandbox::BaselinePolicy(kFSDeniedErrno)) {}
+SandboxBpfBasePolicy::~SandboxBpfBasePolicy() {}
+
+ErrorCode SandboxBpfBasePolicy::EvaluateSyscall(Sandbox* sandbox_compiler,
+                                                int system_call_number) const {
+  DCHECK(baseline_policy_);
+  return baseline_policy_->EvaluateSyscall(sandbox_compiler,
+                                           system_call_number);
+}
+
+int SandboxBpfBasePolicy::GetFSDeniedErrno() {
+  return kFSDeniedErrno;
+}
+
+}  // namespace content.

content/common/sandbox_bpf_base_policy_linux.h

@@ -0,0 +1,40 @@
+// Copyright 2013 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.
+
+#ifndef CONTENT_COMMON_SANDBOX_BPF_BASE_POLICY_LINUX_H_
+#define CONTENT_COMMON_SANDBOX_BPF_BASE_POLICY_LINUX_H_
+
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+#include "sandbox/linux/seccomp-bpf-helpers/baseline_policy.h"
+#include "sandbox/linux/seccomp-bpf/sandbox_bpf_policy.h"
+
+using playground2::ErrorCode;
+using playground2::Sandbox;
+
+namespace content {
+
+// The "baseline" BPF policy for content/. Any content/ seccomp-bpf policy
+// should inherit from it.
+// It implements the main SandboxBpfPolicy interface. Due to its nature
+// as a "kernel attack surface reduction" layer, it's implementation-defined.
+class SandboxBpfBasePolicy : public playground2::SandboxBpfPolicy {
+ public:
+  SandboxBpfBasePolicy();
+  virtual ~SandboxBpfBasePolicy();
+
+  virtual ErrorCode EvaluateSyscall(Sandbox* sandbox_compiler,
+                                    int system_call_number) const OVERRIDE;
+  // Get the errno(3) to return for filesystem errors.
+  static int GetFSDeniedErrno();
+
+ private:
+  // Compose the BaselinePolicy from sandbox/.
+  scoped_ptr<sandbox::BaselinePolicy> baseline_policy_;
+  DISALLOW_COPY_AND_ASSIGN(SandboxBpfBasePolicy);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_COMMON_SANDBOX_BPF_BASE_POLICY_LINUX_H_