Linux sandbox: restrict *kill to the current process.

sandbox/linux/seccomp-bpf-helpers/baseline_policy.h

 // Copyright (c) 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 SANDBOX_LINUX_SECCOMP_BPF_HELPERS_BASELINE_POLICY_H_
 #define SANDBOX_LINUX_SECCOMP_BPF_HELPERS_BASELINE_POLICY_H_
 
 #include "sandbox/linux/sandbox_export.h"
 #include "sandbox/linux/seccomp-bpf/errorcode.h"
 #include "sandbox/linux/seccomp-bpf/sandbox_bpf_policy.h"
 
 namespace sandbox {
 
 class SandboxBPF;
 class SandboxBPFPolicy;
 
 // This is a helper to build seccomp-bpf policies, i.e. policies for a sandbox
 // that reduces the Linux kernel's attack surface. Given its nature, it doesn't
 // have a clear semantics and is mostly "implementation-defined".
 //
-// This returns an object that implements the SandboxBPFPolicy interface with
-// a "baseline" policy within Chromium.
+// This class implements the SandboxBPFPolicy interface with a "baseline"
+// policy for us within Chromium.
 // The "baseline" policy is somewhat arbitrary. All Chromium policies are an
 // alteration of it, and it represents a reasonable common ground to run most
 // code in a sandboxed environment.
+// A baseline policy is only valid for the process for which this object was
+// instanciated (so do not fork() and use it in a child).

[Jorge Lucangeli Obes, 2014/04/29 18:23:43]

You might have missed "instantiated" here.

[jln (very slow on Chromium), 2014/04/29 18:26:03]

I had done it, I swear! .. but then I did git stash because I had already a
bunch of files I was editing.

 class SANDBOX_EXPORT BaselinePolicy : public SandboxBPFPolicy {
  public:
   BaselinePolicy();
   // |fs_denied_errno| is the errno returned when a filesystem access system
   // call is denied.
   explicit BaselinePolicy(int fs_denied_errno);
   virtual ~BaselinePolicy();
 
   virtual ErrorCode EvaluateSyscall(SandboxBPF* sandbox_compiler,
                                     int system_call_number) const OVERRIDE;
 
  private:
   int fs_denied_errno_;
+  pid_t current_pid_;
   DISALLOW_COPY_AND_ASSIGN(BaselinePolicy);
 };
 
 }  // namespace sandbox.
 
 #endif  // SANDBOX_LINUX_SECCOMP_BPF_HELPERS_BASELINE_POLICY_H_