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
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  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     request.setFetchCredentialsMode(allowCredentials == AllowStoredCredentials ? WebURLRequest::FetchCredentialsModeInclude : WebURLRequest::FetchCredentialsModeOmit);
  69
  70     if (securityOrigin)
  71         request.setHTTPOrigin(securityOrigin->toAtomicString());
  72 }
  73
  74 ResourceRequest createAccessControlPreflightRequest(const ResourceRequest& request, SecurityOrigin* securityOrigin)
  75 {
  76     ResourceRequest preflightRequest(request.url());
  77     updateRequestForAccessControl(preflightRequest, securityOrigin, DoNotAllowStoredCredentials);
  78     preflightRequest.setHTTPMethod("OPTIONS");
  79     preflightRequest.setHTTPHeaderField("Access-Control-Request-Method", request.httpMethod());
  80     preflightRequest.setPriority(request.priority());
  81     preflightRequest.setRequestContext(request.requestContext());
  82
  83     const HTTPHeaderMap& requestHeaderFields = request.httpHeaderFields();
  84
  85     if (requestHeaderFields.size() > 0) {
  86         StringBuilder headerBuffer;
  87         HTTPHeaderMap::const_iterator it = requestHeaderFields.begin();
  88         headerBuffer.append(it->key);
  89         ++it;
  90
  91         HTTPHeaderMap::const_iterator end = requestHeaderFields.end();
  92         for (; it != end; ++it) {
  93             headerBuffer.appendLiteral(", ");
  94             headerBuffer.append(it->key);
  95         }
  96
  97         preflightRequest.setHTTPHeaderField("Access-Control-Request-Headers", AtomicString(headerBuffer.toString().lower()));
  98     }
  99
 100     return preflightRequest;
 101 }
 102
 103 static bool isOriginSeparator(UChar ch)
 104 {
 105     return isASCIISpace(ch) || ch == ',';
 106 }
 107
 108 static bool isInterestingStatusCode(int statusCode)
 109 {
 110     // Predicate that gates what status codes should be included in
 111     // console error messages for responses containing no access
 112     // control headers.
 113     return statusCode >= 400;
 114 }
 115
 116 bool passesAccessControlCheck(const ResourceResponse& response, StoredCredentials includeCredentials, SecurityOrigin* securityOrigin, String& errorDescription)
 117 {
 118     AtomicallyInitializedStatic(AtomicString&, accessControlAllowOrigin = *new AtomicString("access-control-allow-origin", AtomicString::ConstructFromLiteral));
 119     AtomicallyInitializedStatic(AtomicString&, accessControlAllowCredentials = *new AtomicString("access-control-allow-credentials", AtomicString::ConstructFromLiteral));
 120
 121     if (!response.httpStatusCode()) {
 122         errorDescription = "Received an invalid response. Origin '" + securityOrigin->toString() + "' is therefore not allowed access.";
 123         return false;
 124     }
 125
 126     const AtomicString& accessControlOriginString = response.httpHeaderField(accessControlAllowOrigin);
 127     if (accessControlOriginString == starAtom) {
 128         // A wildcard Access-Control-Allow-Origin can not be used if credentials are to be sent,
 129         // even with Access-Control-Allow-Credentials set to true.
 130         if (includeCredentials == DoNotAllowStoredCredentials)
 131             return true;
 132         if (response.isHTTP()) {
 133             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.";
 134             return false;
 135         }
 136     } else if (accessControlOriginString != securityOrigin->toAtomicString()) {
 137         if (accessControlOriginString.isNull()) {
 138             errorDescription = "No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin '" + securityOrigin->toString() + "' is therefore not allowed access.";
 139
 140             if (isInterestingStatusCode(response.httpStatusCode()))
 141                 errorDescription.append(" The response had HTTP status code " + String::number(response.httpStatusCode()) + ".");
 142         } else if (accessControlOriginString.string().find(isOriginSeparator, 0) != kNotFound) {
 143             errorDescription = "The 'Access-Control-Allow-Origin' header contains multiple values '" + accessControlOriginString + "', but only one is allowed. Origin '" + securityOrigin->toString() + "' is therefore not allowed access.";
 144         } else {
 145             KURL headerOrigin(KURL(), accessControlOriginString);
 146             if (!headerOrigin.isValid())
 147                 errorDescription = "The 'Access-Control-Allow-Origin' header contains the invalid value '" + accessControlOriginString + "'. Origin '" + securityOrigin->toString() + "' is therefore not allowed access.";
 148             else
 149                 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.";
 150         }
 151         return false;
 152     }
 153
 154     if (includeCredentials == AllowStoredCredentials) {
 155         const AtomicString& accessControlCredentialsString = response.httpHeaderField(accessControlAllowCredentials);
 156         if (accessControlCredentialsString != "true") {
 157             errorDescription = "Credentials flag is 'true', but the 'Access-Control-Allow-Credentials' header is '" + accessControlCredentialsString + "'. It must be 'true' to allow credentials.";
 158             return false;
 159         }
 160     }
 161
 162     return true;
 163 }
 164
 165 bool passesPreflightStatusCheck(const ResourceResponse& response, String& errorDescription)
 166 {
 167     if (response.httpStatusCode() < 200 || response.httpStatusCode() >= 400) {
 168         errorDescription = "Invalid HTTP status code " + String::number(response.httpStatusCode());
 169         return false;
 170     }
 171
 172     return true;
 173 }
 174
 175 void parseAccessControlExposeHeadersAllowList(const String& headerValue, HTTPHeaderSet& headerSet)
 176 {
 177     Vector<String> headers;
 178     headerValue.split(',', false, headers);
 179     for (unsigned headerCount = 0; headerCount < headers.size(); headerCount++) {
 180         String strippedHeader = headers[headerCount].stripWhiteSpace();
 181         if (!strippedHeader.isEmpty())
 182             headerSet.add(strippedHeader);
 183     }
 184 }
 185
 186 bool CrossOriginAccessControl::isLegalRedirectLocation(const KURL& requestURL, String& errorDescription)
 187 {
 188     // CORS restrictions imposed on Location: URL -- http://www.w3.org/TR/cors/#redirect-steps (steps 2 + 3.)
 189     if (!SchemeRegistry::shouldTreatURLSchemeAsCORSEnabled(requestURL.protocol())) {
 190         errorDescription = "The request was redirected to a URL ('" + requestURL.string() + "') which has a disallowed scheme for cross-origin requests.";
 191         return false;
 192     }
 193
 194     if (!(requestURL.user().isEmpty() && requestURL.pass().isEmpty())) {
 195         errorDescription = "The request was redirected to a URL ('" + requestURL.string() + "') containing userinfo, which is disallowed for cross-origin requests.";
 196         return false;
 197     }
 198
 199     return true;
 200 }
 201
 202 bool CrossOriginAccessControl::handleRedirect(Resource* resource, SecurityOrigin* securityOrigin, ResourceRequest& request, const ResourceResponse& redirectResponse, ResourceLoaderOptions& options, String& errorMessage)
 203 {
 204     // http://www.w3.org/TR/cors/#redirect-steps terminology:
 205     const KURL& originalURL = redirectResponse.url();
 206     const KURL& requestURL = request.url();
 207
 208     bool redirectCrossOrigin = !securityOrigin->canRequest(requestURL);
 209
 210     // Same-origin request URLs that redirect are allowed without checking access.
 211     if (!securityOrigin->canRequest(originalURL)) {
 212         // Follow http://www.w3.org/TR/cors/#redirect-steps
 213         String errorDescription;
 214
 215         // Steps 3 & 4 - check if scheme and other URL restrictions hold.
 216         bool allowRedirect = isLegalRedirectLocation(requestURL, errorDescription);
 217         if (allowRedirect) {
 218             // Step 5: perform resource sharing access check.
 219             StoredCredentials withCredentials = resource->lastResourceRequest().allowStoredCredentials() ? AllowStoredCredentials : DoNotAllowStoredCredentials;
 220             allowRedirect = passesAccessControlCheck(redirectResponse, withCredentials, securityOrigin, errorDescription);
 221             if (allowRedirect) {
 222                 RefPtr<SecurityOrigin> originalOrigin = SecurityOrigin::create(originalURL);
 223                 // Step 6: if the request URL origin is not same origin as the original URL's,
 224                 // set the source origin to a globally unique identifier.
 225                 if (!originalOrigin->canRequest(requestURL)) {
 226                     options.securityOrigin = SecurityOrigin::createUnique();
 227                     securityOrigin = options.securityOrigin.get();
 228                 }
 229             }
 230         }
 231         if (!allowRedirect) {
 232             const String& originalOrigin = SecurityOrigin::create(originalURL)->toString();
 233             errorMessage = "Redirect at origin '" + originalOrigin + "' has been blocked from loading by Cross-Origin Resource Sharing policy: " + errorDescription;
 234             return false;
 235         }
 236     }
 237     if (redirectCrossOrigin) {
 238         // If now to a different origin, update/set Origin:.
 239         request.clearHTTPOrigin();
 240         request.setHTTPOrigin(securityOrigin->toAtomicString());
 241         // If the user didn't request credentials in the first place, update our
 242         // state so we neither request them nor expect they must be allowed.
 243         if (options.credentialsRequested == ClientDidNotRequestCredentials)
 244             options.allowCredentials = DoNotAllowStoredCredentials;
 245     }
 246     return true;
 247 }
 248
 249 } // namespace blink