Collect and report kernel warnings.
A flex-based daemon collects kernel warnings by parsing /var/log/messages
as lines are added to it. For every warning the daemon sends a sample
to a sparse UMA histogram using a hash of the warning as the bucket.
Then, if the warning hasn't been seen before, the daemon invokes the
crash collector to upload the warning stack trace.
BUG=chromium:217382
TEST=manually tested (for now), automated test on its way
CQ-DEPEND=Ic8d5773d05d717a275c4a4b5616e0e4c307337b8
CQ-DEPEND=I6a4010acad0ffe20c702bb0fc455e3da7cdf3ac1
Change-Id: I89090e5c2b61ec46b4e740f0895c591728d70e77
Reviewed-on: https://gerrit.chromium.org/gerrit/48277
Commit-Queue: Luigi Semenzato <semenzato@chromium.org>
Reviewed-by: Luigi Semenzato <semenzato@chromium.org>
Tested-by: Luigi Semenzato <semenzato@chromium.org>
diff --git a/crash_reporter/kernel_warning_collector.cc b/crash_reporter/kernel_warning_collector.cc
new file mode 100644
index 0000000..b504f49
--- /dev/null
+++ b/crash_reporter/kernel_warning_collector.cc
@@ -0,0 +1,97 @@
+// Copyright (c) 2012 The Chromium OS 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 "crash-reporter/kernel_warning_collector.h"
+
+#include "base/file_util.h"
+#include "base/logging.h"
+#include "base/string_number_conversions.h"
+#include "base/string_util.h"
+#include "base/stringprintf.h"
+
+namespace {
+const char kExecName[] = "kernel-warning";
+const char kKernelWarningSignatureKey[] = "sig";
+const char kKernelWarningPath[] = "/var/run/kwarn/warning";
+const pid_t kKernelPid = 0;
+const uid_t kRootUid = 0;
+} // namespace
+
+KernelWarningCollector::KernelWarningCollector() {
+}
+
+KernelWarningCollector::~KernelWarningCollector() {
+}
+
+bool KernelWarningCollector::LoadKernelWarning(std::string *content,
+ std::string *hash_string) {
+ FilePath kernel_warning_path(kKernelWarningPath);
+ if (!file_util::ReadFileToString(kernel_warning_path, content)) {
+ LOG(ERROR) << "Could not open " << kKernelWarningPath;
+ return false;
+ }
+ /* Verify that the first line contains an 8-digit hex hash. */
+ *hash_string = content->substr(0, 8);
+ std::vector<uint8> output;
+ if (!base::HexStringToBytes(*hash_string, &output)) {
+ LOG(ERROR) << "Bad hash " << *hash_string << " in " << kKernelWarningPath;
+ return false;
+ }
+ return true;
+}
+
+bool KernelWarningCollector::Collect() {
+ std::string reason = "normal collection";
+ bool feedback = true;
+ if (IsDeveloperImage()) {
+ reason = "always collect from developer builds";
+ feedback = true;
+ } else if (!is_feedback_allowed_function_()) {
+ reason = "no user consent";
+ feedback = false;
+ }
+
+ LOG(INFO) << "Processing kernel warning: " << reason;
+
+ if (!feedback) {
+ return true;
+ }
+
+ std::string kernel_warning;
+ std::string warning_hash;
+ if (!LoadKernelWarning(&kernel_warning, &warning_hash)) {
+ return true;
+ }
+
+ FilePath root_crash_directory;
+ if (!GetCreatedCrashDirectoryByEuid(kRootUid, &root_crash_directory, NULL)) {
+ return true;
+ }
+
+ std::string dump_basename =
+ FormatDumpBasename(kExecName, time(NULL), kKernelPid);
+ FilePath kernel_crash_path = root_crash_directory.Append(
+ StringPrintf("%s.kcrash", dump_basename.c_str()));
+
+ // We must use WriteNewFile instead of file_util::WriteFile as we
+ // do not want to write with root access to a symlink that an attacker
+ // might have created.
+ if (WriteNewFile(kernel_crash_path,
+ kernel_warning.data(),
+ kernel_warning.length()) !=
+ static_cast<int>(kernel_warning.length())) {
+ LOG(INFO) << "Failed to write kernel warning to "
+ << kernel_crash_path.value().c_str();
+ return true;
+ }
+
+ AddCrashMetaData(kKernelWarningSignatureKey, warning_hash);
+ WriteCrashMetaData(
+ root_crash_directory.Append(
+ StringPrintf("%s.meta", dump_basename.c_str())),
+ kExecName, kernel_crash_path.value());
+
+ LOG(INFO) << "Stored kernel warning into " << kernel_crash_path.value();
+ return true;
+}