src/third_party/WebKit/Source/core/fetch/CrossOriginAccessControl.cpp

   1 /*
   2  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
  14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
  17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  *
  25  */
  26
  27 #include "config.h"
  28 #include "core/fetch/CrossOriginAccessControl.h"
  29
  30 #include "core/fetch/Resource.h"
  31 #include "core/fetch/ResourceLoaderOptions.h"
  32 #include "platform/network/HTTPParsers.h"
  33 #include "platform/network/ResourceRequest.h"
  34 #include "platform/network/ResourceResponse.h"
  35 #include "platform/weborigin/SchemeRegistry.h"
  36 #include "platform/weborigin/SecurityOrigin.h"
  37 #include "wtf/Threading.h"
  38 #include "wtf/text/AtomicString.h"
  39 #include "wtf/text/StringBuilder.h"
  40
  41 namespace blink {
  42
  43 static PassOwnPtr<HTTPHeaderSet> createAllowedCrossOriginResponseHeadersSet()
  44 {
  45     OwnPtr<HTTPHeaderSet> headerSet = adoptPtr(new HashSet<String, CaseFoldingHash>);
  46
  47     headerSet->add("cache-control");
  48     headerSet->add("content-language");
  49     headerSet->add("content-type");
  50     headerSet->add("expires");
  51     headerSet->add("last-modified");
  52     headerSet->add("pragma");
  53
  54     return headerSet.release();
  55 }
  56
  57 bool isOnAccessControlResponseHeaderWhitelist(const String& name)
  58 {
  59     AtomicallyInitializedStatic(HTTPHeaderSet*, allowedCrossOriginResponseHeaders = createAllowedCrossOriginResponseHeadersSet().leakPtr());
  60
  61     return allowedCrossOriginResponseHeaders->contains(name);
  62 }
  63
  64 void updateRequestForAccessControl(ResourceRequest& request, SecurityOrigin* securityOrigin, StoredCredentials allowCredentials)
  65 {
  66     request.removeCredentials();
  67     request.setAllowStoredCredentials(allowCredentials == AllowStoredCredentials);
  68
  69     if (securityOrigin)
  70         request.setHTTPOrigin(securityOrigin->toAtomicString());
  71 }
  72
  73 ResourceRequest createAccessControlPreflightRequest(const ResourceRequest& request, SecurityOrigin* securityOrigin)
  74 {
  75     ResourceRequest preflightRequest(request.url());
  76     updateRequestForAccessControl(preflightRequest, securityOrigin, DoNotAllowStoredCredentials);
  77     preflightRequest.setHTTPMethod("OPTIONS");
  78     preflightRequest.setHTTPHeaderField("Access-Control-Request-Method", request.httpMethod());
  79     preflightRequest.setPriority(request.priority());
  80     preflightRequest.setRequestContext(request.requestContext());
  81
  82     const HTTPHeaderMap& requestHeaderFields = request.httpHeaderFields();
  83
  84     if (requestHeaderFields.size() > 0) {
  85         StringBuilder headerBuffer;
  86         HTTPHeaderMap::const_iterator it = requestHeaderFields.begin();
  87         headerBuffer.append(it->key);
  88         ++it;
  89
  90         HTTPHeaderMap::const_iterator end = requestHeaderFields.end();
  91         for (; it != end; ++it) {
  92             headerBuffer.appendLiteral(", ");
  93             headerBuffer.append(it->key);
  94         }
  95
  96         preflightRequest.setHTTPHeaderField("Access-Control-Request-Headers", AtomicString(headerBuffer.toString().lower()));
  97     }
  98
  99     return preflightRequest;
 100 }
 101
 102 static bool isOriginSeparator(UChar ch)
 103 {
 104     return isASCIISpace(ch) || ch == ',';
 105 }
 106
 107 static bool isInterestingStatusCode(int statusCode)
 108 {
 109     // Predicate that gates what status codes should be included in
 110     // console error messages for responses containing no access
 111     // control headers.
 112     return statusCode >= 400;
 113 }
 114
 115 bool passesAccessControlCheck(const ResourceResponse& response, StoredCredentials includeCredentials, SecurityOrigin* securityOrigin, String& errorDescription)
 116 {
 117     AtomicallyInitializedStatic(AtomicString&, accessControlAllowOrigin = *new AtomicString("access-control-allow-origin", AtomicString::ConstructFromLiteral));
 118     AtomicallyInitializedStatic(AtomicString&, accessControlAllowCredentials = *new AtomicString("access-control-allow-credentials", AtomicString::ConstructFromLiteral));
 119
 120     if (!response.httpStatusCode()) {
 121         errorDescription = "Received an invalid response. Origin '" + securityOrigin->toString() + "' is therefore not allowed access.";
 122         return false;
 123     }
 124
 125     const AtomicString& accessControlOriginString = response.httpHeaderField(accessControlAllowOrigin);
 126     if (accessControlOriginString == starAtom) {
 127         // A wildcard Access-Control-Allow-Origin can not be used if credentials are to be sent,
 128         // even with Access-Control-Allow-Credentials set to true.
 129         if (includeCredentials == DoNotAllowStoredCredentials)
 130             return true;
 131         if (response.isHTTP()) {
 132             errorDescription = "A wildcard '*' cannot be used in the 'Access-Control-Allow-Origin' header when the credentials flag is true. Origin '" + securityOrigin->toString() + "' is therefore not allowed access.";
 133             return false;
 134         }
 135     } else if (accessControlOriginString != securityOrigin->toAtomicString()) {
 136         if (accessControlOriginString.isEmpty()) {
 137             errorDescription = "No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin '" + securityOrigin->toString() + "' is therefore not allowed access.";
 138
 139             if (isInterestingStatusCode(response.httpStatusCode()))
 140                 errorDescription.append(" The response had HTTP status code " + String::number(response.httpStatusCode()) + ".");
 141         } else if (accessControlOriginString.string().find(isOriginSeparator, 0) != kNotFound) {
 142             errorDescription = "The 'Access-Control-Allow-Origin' header contains multiple values '" + accessControlOriginString + "', but only one is allowed. Origin '" + securityOrigin->toString() + "' is therefore not allowed access.";
 143         } else {
 144             KURL headerOrigin(KURL(), accessControlOriginString);
 145             if (!headerOrigin.isValid())
 146                 errorDescription = "The 'Access-Control-Allow-Origin' header contains the invalid value '" + accessControlOriginString + "'. Origin '" + securityOrigin->toString() + "' is therefore not allowed access.";
 147             else
 148                 errorDescription = "The 'Access-Control-Allow-Origin' header has a value '" + accessControlOriginString + "' that is not equal to the supplied origin. Origin '" + securityOrigin->toString() + "' is therefore not allowed access.";
 149         }
 150         return false;
 151     }
 152
 153     if (includeCredentials == AllowStoredCredentials) {
 154         const AtomicString& accessControlCredentialsString = response.httpHeaderField(accessControlAllowCredentials);
 155         if (accessControlCredentialsString != "true") {
 156             errorDescription = "Credentials flag is 'true', but the 'Access-Control-Allow-Credentials' header is '" + accessControlCredentialsString + "'. It must be 'true' to allow credentials.";
 157             return false;
 158         }
 159     }
 160
 161     return true;
 162 }
 163
 164 bool passesPreflightStatusCheck(const ResourceResponse& response, String& errorDescription)
 165 {
 166     if (response.httpStatusCode() < 200 || response.httpStatusCode() >= 400) {
 167         errorDescription = "Invalid HTTP status code " + String::number(response.httpStatusCode());
 168         return false;
 169     }
 170
 171     return true;
 172 }
 173
 174 void parseAccessControlExposeHeadersAllowList(const String& headerValue, HTTPHeaderSet& headerSet)
 175 {
 176     Vector<String> headers;
 177     headerValue.split(',', false, headers);
 178     for (unsigned headerCount = 0; headerCount < headers.size(); headerCount++) {
 179         String strippedHeader = headers[headerCount].stripWhiteSpace();
 180         if (!strippedHeader.isEmpty())
 181             headerSet.add(strippedHeader);
 182     }
 183 }
 184
 185 bool CrossOriginAccessControl::isLegalRedirectLocation(const KURL& requestURL, String& errorDescription)
 186 {
 187     // CORS restrictions imposed on Location: URL -- http://www.w3.org/TR/cors/#redirect-steps (steps 2 + 3.)
 188     if (!SchemeRegistry::shouldTreatURLSchemeAsCORSEnabled(requestURL.protocol())) {
 189         errorDescription = "The request was redirected to a URL ('" + requestURL.string() + "') which has a disallowed scheme for cross-origin requests.";
 190         return false;
 191     }
 192
 193     if (!(requestURL.user().isEmpty() && requestURL.pass().isEmpty())) {
 194         errorDescription = "The request was redirected to a URL ('" + requestURL.string() + "') containing userinfo, which is disallowed for cross-origin requests.";
 195         return false;
 196     }
 197
 198     return true;
 199 }
 200
 201 bool CrossOriginAccessControl::handleRedirect(Resource* resource, SecurityOrigin* securityOrigin, ResourceRequest& request, const ResourceResponse& redirectResponse, ResourceLoaderOptions& options, String& errorMessage)
 202 {
 203     // http://www.w3.org/TR/cors/#redirect-steps terminology:
 204     const KURL& originalURL = redirectResponse.url();
 205     const KURL& requestURL = request.url();
 206
 207     bool redirectCrossOrigin = !securityOrigin->canRequest(requestURL);
 208
 209     // Same-origin request URLs that redirect are allowed without checking access.
 210     if (!securityOrigin->canRequest(originalURL)) {
 211         // Follow http://www.w3.org/TR/cors/#redirect-steps
 212         String errorDescription;
 213
 214         // Steps 3 & 4 - check if scheme and other URL restrictions hold.
 215         bool allowRedirect = isLegalRedirectLocation(requestURL, errorDescription);
 216         if (allowRedirect) {
 217             // Step 5: perform resource sharing access check.
 218             StoredCredentials withCredentials = resource->lastResourceRequest().allowStoredCredentials() ? AllowStoredCredentials : DoNotAllowStoredCredentials;
 219             allowRedirect = passesAccessControlCheck(redirectResponse, withCredentials, securityOrigin, errorDescription);
 220             if (allowRedirect) {
 221                 RefPtr<SecurityOrigin> originalOrigin = SecurityOrigin::create(originalURL);
 222                 // Step 6: if the request URL origin is not same origin as the original URL's,
 223                 // set the source origin to a globally unique identifier.
 224                 if (!originalOrigin->canRequest(requestURL)) {
 225                     options.securityOrigin = SecurityOrigin::createUnique();
 226                     securityOrigin = options.securityOrigin.get();
 227                 }
 228             }
 229         }
 230         if (!allowRedirect) {
 231             const String& originalOrigin = SecurityOrigin::create(originalURL)->toString();
 232             errorMessage = "Redirect at origin '" + originalOrigin + "' has been blocked from loading by Cross-Origin Resource Sharing policy: " + errorDescription;
 233             return false;
 234         }
 235     }
 236     if (redirectCrossOrigin) {
 237         // If now to a different origin, update/set Origin:.
 238         request.clearHTTPOrigin();
 239         request.setHTTPOrigin(securityOrigin->toAtomicString());
 240         // If the user didn't request credentials in the first place, update our
 241         // state so we neither request them nor expect they must be allowed.
 242         if (options.credentialsRequested == ClientDidNotRequestCredentials)
 243             options.allowCredentials = DoNotAllowStoredCredentials;
 244     }
 245     return true;
 246 }
 247
 248 } // namespace blink