UMA data collector for cross-site documents(XSD)

content/child/site_isolation_policy.cc

+// 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.
+
+#include "content/child/site_isolation_policy.h"
+
+#include "base/basictypes.h"
+#include "base/logging.h"
+#include "base/metrics/histogram.h"
+#include "base/strings/string_util.h"
+#include "net/base/registry_controlled_domains/registry_controlled_domain.h"
+#include "net/http/http_response_headers.h"
+#include "third_party/WebKit/public/platform/WebHTTPHeaderVisitor.h"
+#include "third_party/WebKit/public/platform/WebString.h"
+#include "third_party/WebKit/public/platform/WebURL.h"
+#include "third_party/WebKit/public/platform/WebURLRequest.h"
+#include "third_party/WebKit/public/platform/WebURLResponse.h"
+#include "third_party/WebKit/public/web/WebDocument.h"
+#include "third_party/WebKit/public/web/WebFrame.h"
+#include "third_party/WebKit/public/web/WebFrameClient.h"
+#include "third_party/WebKit/public/web/WebSecurityOrigin.h"
+#include "third_party/WebKit/public/web/WebView.h"
+
+using WebKit::WebDocument;
+using WebKit::WebString;
+using WebKit::WebURL;
+using WebKit::WebURLResponse;
+using WebKit::WebURLRequest;
+
+namespace content {
+
+namespace {
+
+// MIME types
+const char kTextHtml[] = "text/html";
+const char kTextXml[] = "text/xml";
+const char xAppRssXml[] = "application/rss+xml";
+const char kAppXml[] = "application/xml";
+const char kAppJson[] = "application/json";
+const char kTextJson[] = "text/json";
+const char kTextXjson[] = "text/x-json";
+const char kTextPlain[] = "text/plain";
+
+}  // anonymous namespace
+
+SiteIsolationPolicy::SiteIsolationPolicy(
+    webkit_glue::ResourceLoaderBridge::Peer* original_peer,
+    bool policy_enforced,
+    GURL& frame_origin,
+    GURL& request_url,
+    int request_id,
+    ResourceType::Type resource_type)
+    : original_peer_(original_peer),
+      policy_enforced_(policy_enforced),
+      frame_origin_(frame_origin),
+      request_url_(request_url),
+      request_id_(request_id),
+      resource_type_(resource_type),
+      state_(INIT),
+      cross_site_document_header_(false),
+      confirmed_safe_(false) {
+  // TODO(dsjang): when SiteIsoloation is fully deployed in the browser process,
+  // |frame_origin| will be given from a trusted module.
+}
+
+void SiteIsolationPolicy::OnUploadProgress(uint64 position, uint64 size) {
+  original_peer_->OnUploadProgress(position, size);
+}
+
+void SiteIsolationPolicy::OnDownloadedData(int len) {
+  return original_peer_->OnDownloadedData(len);
+}
+
+void SiteIsolationPolicy::OnReceivedCachedMetadata(const char* data, int len) {
+  return original_peer_->OnReceivedCachedMetadata(data, len);
+}
+
+void SiteIsolationPolicy::OnCompletedRequest(
+    int error_code,
+    bool was_ignored_by_handler,
+    const std::string& security_info,
+    const base::TimeTicks& completion_time) {
+  state_ = COMPLETED;
+  original_peer_->OnCompletedRequest(
+      error_code, was_ignored_by_handler, security_info, completion_time);
+}
+
+bool SiteIsolationPolicy::OnReceivedRedirect(
+    const GURL& new_url,
+    const webkit_glue::ResourceResponseInfo& info,
+    bool* has_new_first_party_for_cookies,
+    GURL* new_first_party_for_cookies) {
+  DCHECK_EQ(state_, INIT);
+  request_url_ = new_url;
+  return original_peer_->OnReceivedRedirect(new_url,
+                                            info,
+                                            has_new_first_party_for_cookies,
+                                            new_first_party_for_cookies);
+}
+
+void SiteIsolationPolicy::OnReceivedResponse(
+    const webkit_glue::ResourceResponseInfo& info) {
+  DCHECK_EQ(state_, INIT);
+  state_ = RESPONSE_RECEIVED;
+
+  UMA_HISTOGRAM_COUNTS("SiteIsolation.AllResponses", 1);
+  original_peer_->OnReceivedResponse(info);
+
+  if (!policy_enforced_)
+    return;
+
+  // See if this is for navigation. If it is, don't block it, under the
+  // assumption that we will put it in an appropriate process.
+  if (ResourceType::IsFrame(resource_type_))
+    return;
+
+  if (!IsBlockableScheme(request_url_))
+    return;
+
+  if (IsSameSite(frame_origin_, request_url_))
+    return;
+
+  SiteIsolationPolicy::CanonicalMimeType canonical_mime_type =
+      GetCanonicalMimeType(info.mime_type);
+
+  if (canonical_mime_type == SiteIsolationPolicy::Others)
+    return;
+
+  // Every CORS request should have the Access-Control-Allow-Origin header even
+  // if it is preceded by a pre-flight request. Therefore, if this is a CORS
+  // request, it has this header.  response.httpHeaderField() internally uses
+  // case-insensitive matching for the header name.
+  std::string access_control_origin;
+
+  // We can use a case-insensitive header name for EnumerateHeader().
+  info.headers->EnumerateHeader(
+      NULL, "access-control-allow-origin", &access_control_origin);
+  if (IsValidCorsHeaderSet(frame_origin_, request_url_, access_control_origin))
+    return;
+
+  // Real XSD data collection starts from here.
+  std::string no_sniff;
+  info.headers->EnumerateHeader(NULL, "x-content-type-options", &no_sniff);
+
+  canonical_mime_type_ = canonical_mime_type;
+  http_status_code_ = info.headers->response_code();
+  no_sniff_ = LowerCaseEqualsASCII(no_sniff, "nosniff");
+
+  cross_site_document_header_ = true;
+}
+
+// These macros are defined here so that we prevent code size bloat-up due to
+// the UMA_HISTOGRAM_* macros. Similar logic is used for recording UMA stats for
+// different MIME types, but we cannot create a helper function for this since
+// UMA_HISTOGRAM_* macros do not accept variables as their bucket names. As a
+// solution, macros are used instead to capture the repeated pattern for
+// recording UMA stats.  TODO(dsjang): this is only needed for collecting UMA
+// stat. Will be deleted when this class is used for actual blocking.
+
+#define SITE_ISOLATION_POLICY_COUNT_BLOCK(BUCKET_PREFIX) \
+    UMA_HISTOGRAM_COUNTS( BUCKET_PREFIX ".Blocked", 1); \
+    if (renderable_status_code) { \
+      UMA_HISTOGRAM_ENUMERATION( \
+          BUCKET_PREFIX ".Blocked.RenderableStatusCode", \
+          resource_type_, \
+          ResourceType::LAST_TYPE + 1); \
+    } else { \
+      UMA_HISTOGRAM_COUNTS(BUCKET_PREFIX ".Blocked.NonRenderableStatusCode",1);\
+    }
+
+#define SITE_ISOLATION_POLICY_COUNT_NO_SNIFF_BLOCK(BUCKET_PREFIX) \
+    UMA_HISTOGRAM_COUNTS( BUCKET_PREFIX ".NoSniffBlocked", 1); \
+    if (renderable_status_code) { \
+      UMA_HISTOGRAM_ENUMERATION( \
+          BUCKET_PREFIX ".NoSniffBlocked.RenderableStatusCode", \
+        resource_type_, \
+        ResourceType::LAST_TYPE + 1); \
+    } else { \
+      UMA_HISTOGRAM_ENUMERATION( \
+          BUCKET_PREFIX ".NoSniffBlocked.NonRenderableStatusCode", \
+        resource_type_, \
+        ResourceType::LAST_TYPE + 1); \
+    }
+
+#define SITE_ISOLATION_POLICY_COUNT_NOTBLOCK(BUCKET_PREFIX) \
+    UMA_HISTOGRAM_COUNTS(BUCKET_PREFIX ".NotBlocked", 1); \
+    if (is_sniffed_for_js) \
+      UMA_HISTOGRAM_COUNTS(BUCKET_PREFIX ".NotBlocked.MaybeJS", 1); \
+
+#define SITE_ISOLATION_POLICY_SNIFF_AND_COUNT(SNIFF_EXPR,BUCKET_PREFIX) \
+  if (SNIFF_EXPR) { \
+    SITE_ISOLATION_POLICY_COUNT_BLOCK(BUCKET_PREFIX) \
+  } else { \
+    if (no_sniff_) { \
+      SITE_ISOLATION_POLICY_COUNT_NO_SNIFF_BLOCK(BUCKET_PREFIX) \
+    } else { \
+      SITE_ISOLATION_POLICY_COUNT_NOTBLOCK(BUCKET_PREFIX) \
+    } \
+  }
+
+void SiteIsolationPolicy::OnReceivedData(const char* data,
+                                         int length,
+                                         int encoded_data_length) {
+  DCHECK(state_ == RESPONSE_RECEIVED || state_ == DATA_RECEIVED);
+  if (!policy_enforced_) {
+    original_peer_->OnReceivedData(data, length, encoded_data_length);
+    return;
+  }
+
+  // The first packet has already been examined.
+  if (state_ == DATA_RECEIVED) {
+    if (!cross_site_document_header_ || confirmed_safe_)
+      original_peer_->OnReceivedData(data, length, encoded_data_length);
+    return;
+  }
+
+  state_ = DATA_RECEIVED;
+
+  // TODO(dsjang): we do not block any response data now. If this is set to
+  // false by any sniffing logic below, it will block all the following response
+  // data to this request.
+  confirmed_safe_ = true;
+
+  if (cross_site_document_header_) {
+    // Record the length of the first received network packet to see if it's
+    // enough for sniffing.
+    UMA_HISTOGRAM_COUNTS("SiteIsolation.XSD.DataLength", length);
+
+    // Record the number of cross-site document responses with a specific mime
+    // type (text/html, text/xml, etc).
+    UMA_HISTOGRAM_ENUMERATION(
+        "SiteIsolation.XSD.MimeType",
+        canonical_mime_type_,
+        MaxCanonicalMimeType);
+
+    // The content is blocked if it is sniffed for HTML/JSON/XML. When the
+    // blocked response is with an error status code, it is not disruptive by
+    // the following reasons : 1) the blocked content is not a binary object
+    // (such as an image) since it is sniffed for text; 2) then, this blocking
+    // only breaks the renderer behavior only if it is either JavaScript or
+    // CSS. However, the renderer doesn't use the contents of JS/CSS with
+    // unaffected status code (e.g, 404). 3) the renderer is expected not to use
+    // the cross-site document content for purposes other than JS/CSS (e.g,
+    // XHR).
+    bool renderable_status_code =
+        IsRenderableStatusCodeForDocument(http_status_code_);
+
+    // This is only used for false-negative analysis for non-blocked resources.
+    bool is_sniffed_for_js = SniffForJS(data, length);
+
+    // Record the number of responses whose content is sniffed for what its mime
+    // type claims it to be. For example, we apply a HTML sniffer for a document
+    // tagged with text/html here. Whenever this check becomes true, we'll block
+    // the response.
+    switch (canonical_mime_type_) {
+      case SiteIsolationPolicy::HTML:
+        SITE_ISOLATION_POLICY_SNIFF_AND_COUNT(SniffForHTML(data, length),
+                                              "SiteIsolation.XSD.HTML");
+        break;
+      case SiteIsolationPolicy::XML:
+        SITE_ISOLATION_POLICY_SNIFF_AND_COUNT(SniffForXML(data, length),
+                                              "SiteIsolation.XSD.XML");
+        break;
+      case SiteIsolationPolicy::JSON:
+        SITE_ISOLATION_POLICY_SNIFF_AND_COUNT(SniffForJSON(data, length),
+                                              "SiteIsolation.XSD.JSON");
+        break;
+      case SiteIsolationPolicy::Plain:
+        if (SniffForHTML(data, length)) {
+          SITE_ISOLATION_POLICY_COUNT_BLOCK("SiteIsolation.XSD.Plain.HTML");
+        } else if (SniffForXML(data, length)) {
+          SITE_ISOLATION_POLICY_COUNT_BLOCK("SiteIsolation.XSD.Plain.XML");
+        } else if (SniffForJSON(data, length)) {
+          SITE_ISOLATION_POLICY_COUNT_BLOCK("SiteIsolation.XSD.Plain.JSON");
+        } else if (is_sniffed_for_js) {
+          if (no_sniff_) {
+            SITE_ISOLATION_POLICY_COUNT_NO_SNIFF_BLOCK(
+                "SiteIsolation.XSD.Plain");
+          } else {
+            SITE_ISOLATION_POLICY_COUNT_NOTBLOCK("SiteIsolation.XSD.Plain");
+          }
+        }
+        break;
+      default:
+        NOTREACHED() << "Not a blockable mime type. This mime type shouldn't "
+                        "reach here.";
+        break;
+    }
+    original_peer_->OnReceivedData(data, length, encoded_data_length);

[darin (slow to review), 2013/08/20 23:47:05]

nit: having the same code in both branches indicates that the code should be
moved to after the branch.  there is no need for "else" here.

it looks like you have made this code capable of not only performing
measurements but also being close to what would be needed for enforcement. 
maybe it would be better to just focus initially on what is needed to perform
measurements.

[dsjang, 2013/08/21 18:49:57]

I'm switching back to the older version of SiteIsolationPolicy with only static
members, and the enforcement part is moved from SiteIsolationPolicy to 
ResourceDispatcher::OnReceivedData(), which calls
SiteIsolationPolicy::OnReceivedData().

On 2013/08/20 23:47:05, darin wrote:

+  } else
+    original_peer_->OnReceivedData(data, length, encoded_data_length);
+}
+
+#undef SITE_ISOLATION_POLICY_COUNT_NOTBLOCK
+#undef SITE_ISOLATION_POLICY_SNIFF_AND_COUNT
+#undef SITE_ISOLATION_POLICY_COUNT_BLOCK
+
+SiteIsolationPolicy::CanonicalMimeType
+SiteIsolationPolicy::GetCanonicalMimeType(const std::string& mime_type) {
+  if (LowerCaseEqualsASCII(mime_type, kTextHtml)) {
+    return SiteIsolationPolicy::HTML;
+  }
+
+  if (LowerCaseEqualsASCII(mime_type, kTextPlain)) {
+    return SiteIsolationPolicy::Plain;
+  }
+
+  if (LowerCaseEqualsASCII(mime_type, kAppJson) ||
+      LowerCaseEqualsASCII(mime_type, kTextJson) ||
+      LowerCaseEqualsASCII(mime_type, kTextXjson)) {
+    return SiteIsolationPolicy::JSON;
+  }
+
+  if (LowerCaseEqualsASCII(mime_type, kTextXml) ||
+      LowerCaseEqualsASCII(mime_type, xAppRssXml) ||
+      LowerCaseEqualsASCII(mime_type, kAppXml)) {
+    return SiteIsolationPolicy::XML;
+  }
+
+ return SiteIsolationPolicy::Others;
+
+}
+
+bool SiteIsolationPolicy::IsBlockableScheme(const GURL& url) {
+  // We exclude ftp:// from here. FTP doesn't provide a Content-Type
+  // header which our policy depends on, so we cannot protect any
+  // document from FTP servers.
+  return url.SchemeIs("http") || url.SchemeIs("https");
+}
+
+bool SiteIsolationPolicy::IsSameSite(const GURL& frame_origin,
+                                     const GURL& response_url) {
+  if (!frame_origin.is_valid() || !response_url.is_valid())
+    return false;
+
+  if (frame_origin.scheme() != response_url.scheme())
+    return false;
+
+  // SameDomainOrHost() extracts the effective domains (public suffix plus one)
+  // from the two URLs and compare them.
+  // TODO(dsjang): use INCLUDE_PRIVATE_REGISTRIES when http://crbug.com/7988 is
+  // fixed.
+  return net::registry_controlled_domains::SameDomainOrHost(
+      frame_origin,
+      response_url,
+      net::registry_controlled_domains::EXCLUDE_PRIVATE_REGISTRIES);
+}
+
+// We don't use Webkit's existing CORS policy implementation since
+// their policy works in terms of origins, not sites. For example,
+// when frame is sub.a.com and it is not allowed to access a document
+// with sub1.a.com. But under Site Isolation, it's allowed.
+bool SiteIsolationPolicy::IsValidCorsHeaderSet(
+    GURL& frame_origin,
+    GURL& website_origin,
+    std::string access_control_origin) {
+  // Many websites are sending back "\"*\"" instead of "*". This is
+  // non-standard practice, and not supported by Chrome. Refer to
+  // CrossOriginAccessControl::passesAccessControlCheck().
+
+  // TODO(dsjang): * is not allowed for the response from a request
+  // with cookies. This allows for more than what the renderer will
+  // eventually be able to receive, so we won't see illegal cross-site
+  // documents allowed by this. We have to find a way to see if this
+  // response is from a cookie-tagged request or not in the future.
+  if (access_control_origin == "*")
+    return true;
+
+  // TODO(dsjang): The CORS spec only treats a fully specified URL, except for
+  // "*", but many websites are using just a domain for access_control_origin,
+  // and this is blocked by Webkit's CORS logic here :
+  // CrossOriginAccessControl::passesAccessControlCheck(). GURL is set
+  // is_valid() to false when it is created from a URL containing * in the
+  // domain part.
+
+  GURL cors_origin(access_control_origin);
+  return IsSameSite(frame_origin, cors_origin);
+}
+
+// This function is a slight modification of |net::SniffForHTML|.
+bool SiteIsolationPolicy::SniffForHTML(const char* data, size_t length) {
+  // The content sniffer used by Chrome and Firefox are using "<!--"
+  // as one of the HTML signatures, but it also appears in valid
+  // JavaScript, considered as well-formed JS by the browser.  Since
+  // we do not want to block any JS, we exclude it from our HTML
+  // signatures. This can weaken our document block policy, but we can
+  // break less websites.
+  // TODO(dsjang): parameterize |net::SniffForHTML| with an option
+  // that decides whether to include <!-- or not, so that we can
+  // remove this function.
+  const char* html_signatures[] = {"<!DOCTYPE html",  // HTML5 spec
+                                   "<script",         // HTML5 spec, Mozilla
+                                   "<html",           // HTML5 spec, Mozilla
+                                   "<head",           // HTML5 spec, Mozilla
+                                   "<iframe",         // Mozilla
+                                   "<h1",             // Mozilla
+                                   "<div",            // Mozilla
+                                   "<font",           // Mozilla
+                                   "<table",          // Mozilla
+                                   "<a",              // Mozilla
+                                   "<style",          // Mozilla
+                                   "<title",          // Mozilla
+                                   "<b",              // Mozilla
+                                   "<body",           // Mozilla
+                                   "<br", "<p"        // Mozilla
+  };
+
+  if (MatchesSignature(
+          data, length, html_signatures, arraysize(html_signatures)))
+    return true;
+
+  // "<!--" is specially treated since web JS can use "<!--" "-->" pair for
+  // comments.
+  const char* comment_begins[] = {"<!--" };
+
+  if (MatchesSignature(
+          data, length, comment_begins, arraysize(comment_begins))) {
+    // Search for --> and do SniffForHTML after that. If we can find the
+    // comment's end, we start HTML sniffing from there again.
+    const char end_comment[] = "-->";
+    const size_t end_comment_size = strlen(end_comment);
+
+    for (size_t i = 0; i <= length - end_comment_size; ++i) {
+      if (!strncmp(data + i, end_comment, end_comment_size)) {
+        size_t skipped = i + end_comment_size;
+        return SniffForHTML(data + skipped, length - skipped);
+      }
+    }
+  }
+
+  return false;
+}
+
+bool SiteIsolationPolicy::SniffForXML(const char* data, size_t length) {
+  // TODO(dsjang): Chrome's mime_sniffer is using strncasecmp() for
+  // this signature. However, XML is case-sensitive. Don't we have to
+  // be more lenient only to block documents starting with the exact
+  // string <?xml rather than <?XML ?
+  const char* xml_signatures[] = {"<?xml"  // Mozilla
+  };
+  return MatchesSignature(
+      data, length, xml_signatures, arraysize(xml_signatures));
+}
+
+bool SiteIsolationPolicy::SniffForJSON(const char* data, size_t length) {
+  // TODO(dsjang): We have to come up with a better way to sniff
+  // JSON. However, even RE cannot help us that much due to the fact
+  // that we don't do full parsing.  This DFA starts with state 0, and
+  // finds {, "/' and : in that order. We're avoiding adding a
+  // dependency on a regular expression library.
+  const int kInitState = 0;
+  const int kLeftBraceState = 1;
+  const int kLeftQuoteState = 2;
+  const int kColonState = 3;
+  const int kDeadState = 4;
+
+  int state = kInitState;
+  for (size_t i = 0; i < length && state < kColonState; ++i) {
+    const char c = data[i];
+    if (c == ' ' || c == '\t' || c == '\r' || c == '\n')
+      continue;
+
+    switch (state) {
+      case kInitState:
+        if (c == '{')
+          state = kLeftBraceState;
+        else
+          state = kDeadState;
+        break;
+      case kLeftBraceState:
+        if (c == '\"' || c == '\'')
+          state = kLeftQuoteState;
+        else
+          state = kDeadState;
+        break;
+      case kLeftQuoteState:
+        if (c == ':')
+          state = kColonState;
+        break;
+      default:
+        NOTREACHED();
+        break;
+    }
+  }
+  return state == kColonState;
+}
+
+bool SiteIsolationPolicy::MatchesSignature(const char* raw_data,
+                                           size_t raw_length,
+                                           const char* signatures[],
+                                           size_t arr_size) {
+  size_t start = 0;
+  // Skip white characters at the beginning of the document.
+  for (start = 0; start < raw_length; ++start) {
+    char c = raw_data[start];
+    if (!(c == ' ' || c == '\t' || c == '\r' || c == '\n'))
+      break;
+  }
+
+  // There is no not-whitespace character in this document.
+  if (!(start < raw_length))
+    return false;
+
+  const char* data = raw_data + start;
+  size_t length = raw_length - start;
+
+  for (size_t sig_index = 0; sig_index < arr_size; ++sig_index) {
+    const char* signature = signatures[sig_index];
+    size_t signature_length = strlen(signature);
+
+    if (length < signature_length)
+      continue;
+
+    if (!base::strncasecmp(signature, data, signature_length))
+      return true;
+  }
+  return false;
+}
+
+bool SiteIsolationPolicy::IsRenderableStatusCodeForDocument(int status_code) {
+  // Chrome only uses the content of a response with one of these status codes
+  // for CSS/JavaScript. For images, Chrome just ignores status code.
+  const int renderable_status_code[] = {200, 201, 202, 203, 206, 300, 301, 302,
+                                        303, 305, 306, 307};
+  for (size_t i = 0; i < arraysize(renderable_status_code); ++i) {
+    if (renderable_status_code[i] == status_code)
+      return true;
+  }
+  return false;
+}
+
+bool SiteIsolationPolicy::SniffForJS(const char* data, size_t length) {
+  // TODO(dsjang): This is a real hack. The only purpose of this function is to
+  // try to see if there's any possibility that this data can be JavaScript
+  // (superset of JS). This function will be removed once UMA stats are
+  // gathered.
+
+  // Search for "var " for JS detection.
+  for (size_t i = 0; i < length - 3; ++i) {
+    if (strncmp(data + i, "var ", 4) == 0)
+      return true;
+  }
+  return false;
+}
+
+}  // namespace content