Introduce a flag to cap `referer` length to something reasonable.
This patch measures the length of `referer` header values in the
status quo, and introduces a flag which will strip the header down
to its origin if a configurable limit is exceeded.
We'll run some experiments once we're gathering data to determine
what a reasonable limit might look like.
Bug: 959757
Change-Id: I56e10af369399e19dfc92e0245f896804b696210
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1595872
Reviewed-by: Matt Menke <[email protected]>
Reviewed-by: Robert Kaplow <[email protected]>
Commit-Queue: Mike West <[email protected]>
Cr-Commit-Position: refs/heads/master@{#657784}
diff --git a/net/url_request/url_request_http_job.cc b/net/url_request/url_request_http_job.cc
index 0abab13..1412493 100644
--- a/net/url_request/url_request_http_job.cc
+++ b/net/url_request/url_request_http_job.cc
@@ -17,6 +17,7 @@
#include "base/metrics/field_trial.h"
#include "base/metrics/histogram_functions.h"
#include "base/metrics/histogram_macros.h"
+#include "base/numerics/safe_conversions.h"
#include "base/rand_util.h"
#include "base/single_thread_task_runner.h"
#include "base/strings/string_util.h"
@@ -25,6 +26,7 @@
#include "base/time/time.h"
#include "base/trace_event/trace_event.h"
#include "base/values.h"
+#include "net/base/features.h"
#include "net/base/host_port_pair.h"
#include "net/base/http_user_agent_settings.h"
#include "net/base/load_flags.h"
@@ -340,8 +342,17 @@
// Our consumer should have made sure that this is a safe referrer. See for
// instance WebCore::FrameLoader::HideReferrer.
if (referrer.is_valid()) {
+ std::string referer_value = referrer.spec();
+ UMA_HISTOGRAM_COUNTS_10000("Referrer.HeaderLength", referer_value.length());
+ if (base::FeatureList::IsEnabled(features::kCapRefererHeaderLength) &&
+ base::saturated_cast<int>(referer_value.length()) >
+ features::kMaxRefererHeaderLength.Get()) {
+ // Strip the referrer down to its origin, but ensure that it's serialized
+ // as a URL (e.g. retaining a trailing `/` character).
+ referer_value = url::Origin::Create(referrer).GetURL().spec();
+ }
request_info_.extra_headers.SetHeader(HttpRequestHeaders::kReferer,
- referrer.spec());
+ referer_value);
}
request_info_.extra_headers.SetHeaderIfMissing(
