| // 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 "content/common/cross_site_document_classifier.h" |
| |
| #include "base/command_line.h" |
| #include "base/lazy_instance.h" |
| #include "base/logging.h" |
| #include "base/macros.h" |
| #include "base/metrics/histogram_macros.h" |
| #include "base/strings/string_util.h" |
| #include "content/public/common/content_switches.h" |
| #include "content/public/common/resource_response_info.h" |
| #include "net/base/registry_controlled_domains/registry_controlled_domain.h" |
| #include "net/http/http_response_headers.h" |
| |
| using base::StringPiece; |
| |
| namespace content { |
| |
| namespace { |
| |
| // MIME types |
| const char kTextHtml[] = "text/html"; |
| const char kTextXml[] = "text/xml"; |
| const char kAppRssXml[] = "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"; |
| |
| bool MatchesSignature(StringPiece data, |
| const StringPiece signatures[], |
| size_t arr_size) { |
| size_t offset = data.find_first_not_of(" \t\r\n"); |
| // There is no not-whitespace character in this document. |
| if (offset == base::StringPiece::npos) |
| return false; |
| |
| data.remove_prefix(offset); |
| for (size_t sig_index = 0; sig_index < arr_size; ++sig_index) { |
| if (base::StartsWith(data, signatures[sig_index], |
| base::CompareCase::INSENSITIVE_ASCII)) |
| return true; |
| } |
| return false; |
| } |
| |
| } // namespace |
| |
| CrossSiteDocumentMimeType CrossSiteDocumentClassifier::GetCanonicalMimeType( |
| const std::string& mime_type) { |
| if (base::LowerCaseEqualsASCII(mime_type, kTextHtml)) { |
| return CROSS_SITE_DOCUMENT_MIME_TYPE_HTML; |
| } |
| |
| if (base::LowerCaseEqualsASCII(mime_type, kTextPlain)) { |
| return CROSS_SITE_DOCUMENT_MIME_TYPE_PLAIN; |
| } |
| |
| if (base::LowerCaseEqualsASCII(mime_type, kAppJson) || |
| base::LowerCaseEqualsASCII(mime_type, kTextJson) || |
| base::LowerCaseEqualsASCII(mime_type, kTextXjson)) { |
| return CROSS_SITE_DOCUMENT_MIME_TYPE_JSON; |
| } |
| |
| if (base::LowerCaseEqualsASCII(mime_type, kTextXml) || |
| base::LowerCaseEqualsASCII(mime_type, kAppRssXml) || |
| base::LowerCaseEqualsASCII(mime_type, kAppXml)) { |
| return CROSS_SITE_DOCUMENT_MIME_TYPE_XML; |
| } |
| |
| return CROSS_SITE_DOCUMENT_MIME_TYPE_OTHERS; |
| } |
| |
| bool CrossSiteDocumentClassifier::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(url::kHttpScheme) || url.SchemeIs(url::kHttpsScheme); |
| } |
| |
| bool CrossSiteDocumentClassifier::IsSameSite(const url::Origin& frame_origin, |
| const GURL& response_url) { |
| if (frame_origin.unique() || !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. |
| return net::registry_controlled_domains::SameDomainOrHost( |
| response_url, frame_origin, |
| net::registry_controlled_domains::INCLUDE_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 CrossSiteDocumentClassifier::IsValidCorsHeaderSet( |
| const url::Origin& frame_origin, |
| const GURL& website_origin, |
| const 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 CrossSiteDocumentClassifier::SniffForHTML(StringPiece data) { |
| // 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 |
| #include <stddef.h> |
| |
| // that decides whether to include <!-- or not, so that we can |
| // remove this function. |
| // TODO(dsjang): Once CrossSiteDocumentClassifier is moved into the browser |
| // process, we should do single-thread checking here for the static |
| // initializer. |
| static const StringPiece kHtmlSignatures[] = { |
| StringPiece("<!doctype html"), // HTML5 spec |
| StringPiece("<script"), // HTML5 spec, Mozilla |
| StringPiece("<html"), // HTML5 spec, Mozilla |
| StringPiece("<head"), // HTML5 spec, Mozilla |
| StringPiece("<iframe"), // Mozilla |
| StringPiece("<h1"), // Mozilla |
| StringPiece("<div"), // Mozilla |
| StringPiece("<font"), // Mozilla |
| StringPiece("<table"), // Mozilla |
| StringPiece("<a"), // Mozilla |
| StringPiece("<style"), // Mozilla |
| StringPiece("<title"), // Mozilla |
| StringPiece("<b"), // Mozilla |
| StringPiece("<body"), // Mozilla |
| StringPiece("<br"), // Mozilla |
| StringPiece("<p") // Mozilla |
| }; |
| |
| while (data.length() > 0) { |
| if (MatchesSignature(data, kHtmlSignatures, arraysize(kHtmlSignatures))) |
| return true; |
| |
| // If we cannot find "<!--", we fail sniffing this as HTML. |
| static const StringPiece kCommentBegins[] = {StringPiece("<!--")}; |
| if (!MatchesSignature(data, kCommentBegins, arraysize(kCommentBegins))) |
| break; |
| |
| // Search for --> and do SniffForHTML after that. If we can find the |
| // comment's end, we start HTML sniffing from there again. |
| static const char kEndComment[] = "-->"; |
| size_t offset = data.find(kEndComment); |
| if (offset == base::StringPiece::npos) |
| break; |
| |
| // Proceed to the index next to the ending comment (-->). |
| data.remove_prefix(offset + strlen(kEndComment)); |
| } |
| |
| return false; |
| } |
| |
| bool CrossSiteDocumentClassifier::SniffForXML(base::StringPiece data) { |
| // 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 ? |
| // TODO(dsjang): Once CrossSiteDocumentClassifier is moved into the browser |
| // process, we should do single-thread checking here for the static |
| // initializer. |
| static const StringPiece kXmlSignatures[] = {StringPiece("<?xml")}; |
| return MatchesSignature(data, kXmlSignatures, arraysize(kXmlSignatures)); |
| } |
| |
| bool CrossSiteDocumentClassifier::SniffForJSON(base::StringPiece data) { |
| // 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. |
| enum { |
| kStartState, |
| kLeftBraceState, |
| kLeftQuoteState, |
| kColonState, |
| kTerminalState, |
| } state = kStartState; |
| |
| size_t length = data.length(); |
| 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 kStartState: |
| if (c == '{') |
| state = kLeftBraceState; |
| else |
| state = kTerminalState; |
| break; |
| case kLeftBraceState: |
| if (c == '\"' || c == '\'') |
| state = kLeftQuoteState; |
| else |
| state = kTerminalState; |
| break; |
| case kLeftQuoteState: |
| if (c == ':') |
| state = kColonState; |
| break; |
| case kColonState: |
| case kTerminalState: |
| NOTREACHED(); |
| break; |
| } |
| } |
| return state == kColonState; |
| } |
| |
| } // namespace content |