Add SeccompSupportDetector for Android.

chrome/browser/android/seccomp_support_detector.cc

Index: chrome/browser/android/seccomp_support_detector.cc
diff --git a/chrome/browser/android/seccomp_support_detector.cc b/chrome/browser/android/seccomp_support_detector.cc
new file mode 100644
index 0000000000000000000000000000000000000000..4488aee11afb63b5c9badec05149704050916f9c
--- /dev/null
+++ b/chrome/browser/android/seccomp_support_detector.cc
@@ -0,0 +1,127 @@
+// Copyright 2015 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 "chrome/browser/android/seccomp_support_detector.h"
+
+#include <stdio.h>
+#include <sys/utsname.h>
+
+#include "base/message_loop/message_loop_proxy.h"
+#include "base/metrics/histogram_macros.h"
+#include "base/metrics/sparse_histogram.h"
+#include "chrome/common/chrome_utility_messages.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/utility_process_host.h"
+
+using content::BrowserThread;
+
+enum AndroidSeccompStatus {
+  DETECTION_FAILED,  // The process crashed during detection.
+  NOT_SUPPORTED,     // Kernel has no seccomp support.
+  SUPPORTED,         // Kernel has seccomp support.
+  LAST_STATUS
+};
+
+// static
+void SeccompSupportDetector::StartDetection() {
+  // This is instantiated here, and then ownership is maintained by the
+  // Closure objects when the object is being passed between threads. A
+  // reference is also taken by the UtilityProcessHost, which will release
+  // it when the process exits.
+  scoped_refptr<SeccompSupportDetector> detector(new SeccompSupportDetector());
+  BrowserThread::PostBlockingPoolTask(FROM_HERE,
+      base::Bind(&SeccompSupportDetector::DetectKernelVersion, detector));
+}
+
+SeccompSupportDetector::SeccompSupportDetector() : prctl_detected_(false) {
+}
+
+SeccompSupportDetector::~SeccompSupportDetector() {
+}
+
+void SeccompSupportDetector::DetectKernelVersion() {
+  DCHECK(BrowserThread::GetBlockingPool()->RunsTasksOnCurrentThread());
+
+  // This method will report the kernel major and minor versions by
+  // taking the lower 16 bits of each version number and combining
+  // the two into a 32-bit number.
+
+  utsname uts;
+  if (uname(&uts) == 0) {
+    int major, minor;
+    if (sscanf(uts.release, "%d.%d", &major, &minor) == 2) {
+      int version = ((major & 0xFFFF) << 16) | (minor & 0xFFFF);
+      UMA_HISTOGRAM_SPARSE_SLOWLY("Android.KernelVersion", version);
+    }
+  }
+
+#if defined(USE_SECCOMP_BPF)
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+      base::Bind(&SeccompSupportDetector::DetectSeccomp, this));
+#else
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+      base::Bind(&SeccompSupportDetector::OnDetectPrctl, this, false));
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+      base::Bind(&SeccompSupportDetector::OnDetectSyscall, this, false));
+#endif
+}
+
+void SeccompSupportDetector::DetectSeccomp() {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  content::UtilityProcessHost* utility_process_host =
+      content::UtilityProcessHost::Create(
+          this, base::MessageLoopProxy::current());
+  utility_process_host->Send(new ChromeUtilityMsg_DetectSeccompSupport());
+}
+
+void SeccompSupportDetector::OnProcessCrashed(int exit_code) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  // The process crashed. Since prctl detection happens first, report which
+  // probe failed.
+  if (prctl_detected_) {
+    UMA_HISTOGRAM_ENUMERATION("Android.SeccompStatus.Syscall",
+                              DETECTION_FAILED,
+                              LAST_STATUS);
+  } else {
+    UMA_HISTOGRAM_ENUMERATION("Android.SeccompStatus.Prctl",
+                              DETECTION_FAILED,
+                              LAST_STATUS);
+  }
+}
+
+bool SeccompSupportDetector::OnMessageReceived(const IPC::Message& message) {
+  bool handled = false;
+  IPC_BEGIN_MESSAGE_MAP(SeccompSupportDetector, message)
+    IPC_MESSAGE_HANDLER(ChromeUtilityHostMsg_DetectSeccompSupport_ResultPrctl,
+                        OnDetectPrctl)
+    IPC_MESSAGE_HANDLER(ChromeUtilityHostMsg_DetectSeccompSupport_ResultSyscall,
+                        OnDetectSyscall)
+    IPC_MESSAGE_UNHANDLED(handled = false)
+  IPC_END_MESSAGE_MAP()
+  return handled;
+}
+
+void SeccompSupportDetector::OnDetectPrctl(bool prctl_supported) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  DCHECK(!prctl_detected_);
+
+  prctl_detected_ = true;
+
+  UMA_HISTOGRAM_ENUMERATION("Android.SeccompStatus.Prctl",
+                            prctl_supported ? SUPPORTED : NOT_SUPPORTED,
+                            LAST_STATUS);
+}
+
+void SeccompSupportDetector::OnDetectSyscall(bool syscall_supported) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  DCHECK(prctl_detected_);
+
+  UMA_HISTOGRAM_ENUMERATION("Android.SeccompStatus.Syscall",
+                            syscall_supported ? SUPPORTED : NOT_SUPPORTED,
+                            LAST_STATUS);
+
+  // The utility process will shutdown after this, and this object will
+  // be deleted when the UtilityProcessHost releases its reference.
+}