Only allow insecure object-src directives for whitelisted mime types

extensions/common/csp_validator.cc

 // Copyright 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 "extensions/common/csp_validator.h"
 
 #include <vector>
 
 #include "base/strings/string_split.h"
 #include "base/strings/string_tokenizer.h"
 #include "base/strings/string_util.h"
 #include "content/public/common/url_constants.h"
 #include "extensions/common/constants.h"
 #include "net/base/registry_controlled_domains/registry_controlled_domain.h"
 
 namespace extensions {
 
 namespace csp_validator {
 
 namespace {
 
 const char kDefaultSrc[] = "default-src";
 const char kScriptSrc[] = "script-src";
 const char kObjectSrc[] = "object-src";
+const char kPluginTypes[] = "plugin-types";
 
 const char kSandboxDirectiveName[] = "sandbox";
 const char kAllowSameOriginToken[] = "allow-same-origin";
 const char kAllowTopNavigation[] = "allow-top-navigation";
 
+// This is the list of plugin types which are fully sandboxed and are safe to
+// load up in an extension, regardless of the URL they are navigated to.
+const char* const kSandboxedPluginTypes[] = {
+  "application/pdf",
+  "application/x-pnacl"
+};
+
 struct DirectiveStatus {
   explicit DirectiveStatus(const char* name)
     : directive_name(name)
     , seen_in_policy(false)
     , is_secure(false) {
   }
 
   const char* directive_name;
   bool seen_in_policy;
   bool is_secure;
@@ skipping 60 matching lines @@
 
   // Wildcards on subdomains of a TLD are not allowed.
   size_t registry_length = net::registry_controlled_domains::GetRegistryLength(
       host,
       net::registry_controlled_domains::INCLUDE_UNKNOWN_REGISTRIES,
       net::registry_controlled_domains::INCLUDE_PRIVATE_REGISTRIES);
   return registry_length != 0;
 }
 
 bool HasOnlySecureTokens(base::StringTokenizer& tokenizer,
-                         Manifest::Type type) {
+                         int options) {
   while (tokenizer.GetNext()) {
     std::string source = tokenizer.token();
     base::StringToLowerASCII(&source);
 
     // We might need to relax this whitelist over time.
     if (source == "'self'" ||
         source == "'none'" ||
         source == "http://127.0.0.1" ||
         LowerCaseEqualsASCII(source, "blob:") ||
         LowerCaseEqualsASCII(source, "filesystem:") ||
         LowerCaseEqualsASCII(source, "http://localhost") ||
         StartsWithASCII(source, "http://127.0.0.1:", true) ||
         StartsWithASCII(source, "http://localhost:", true) ||
         isNonWildcardTLD(source, "https://", true) ||
         isNonWildcardTLD(source, "chrome://", false) ||
         isNonWildcardTLD(source,
                          std::string(extensions::kExtensionScheme) +
                          url::kStandardSchemeSeparator,
                          false) ||
         StartsWithASCII(source, "chrome-extension-resource:", true)) {
       continue;
     }
 
-    // crbug.com/146487
-    if (type == Manifest::TYPE_EXTENSION ||
-        type == Manifest::TYPE_LEGACY_PACKAGED_APP) {
+    if (options & OPTIONS_ALLOW_UNSAFE_EVAL) {
       if (source == "'unsafe-eval'")
         continue;
     }
 
     return false;
   }
 
   return true;  // Empty values default to 'none', which is secure.
 }
 
 // Returns true if |directive_name| matches |status.directive_name|.
 bool UpdateStatus(const std::string& directive_name,
                   base::StringTokenizer& tokenizer,
                   DirectiveStatus* status,
-                  Manifest::Type type) {
+                  int options) {
   if (status->seen_in_policy)
     return false;
   if (directive_name != status->directive_name)
     return false;
   status->seen_in_policy = true;
-  status->is_secure = HasOnlySecureTokens(tokenizer, type);
+  status->is_secure = HasOnlySecureTokens(tokenizer, options);
   return true;
 }
 
+// Parses the plugin-types directive and returns the list of mime types
+// specified in |plugin_types|.
+bool ParsePluginTypes(const std::string& directive_name,
+                      base::StringTokenizer& tokenizer,
+                      std::vector<std::string>* plugin_types) {
+  DCHECK(plugin_types);
+
+  if (directive_name != kPluginTypes || !plugin_types->empty())
+    return false;
+
+  while (tokenizer.GetNext()) {
+    std::string mime_type = tokenizer.token();
+    base::StringToLowerASCII(&mime_type);
+    // Since we're comparing the mime types to a whitelist, we don't check them
+    // for strict validity right now.
+    plugin_types->push_back(mime_type);
+  }
+
+  return true;
+}
+
+// Returns true if the |plugin_type| is one of the fully sandboxed plugin types.
+bool PluginTypeAllowed(const std::string& plugin_type) {
+  for (size_t i = 0; i < arraysize(kSandboxedPluginTypes); ++i) {
+    if (plugin_type == kSandboxedPluginTypes[i])
+      return true;
+  }
+  return false;
+}
+
+// Returns true if the policy is allowed to contain an insecure object-src
+// directive. This requires OPTIONS_ALLOW_INSECURE_OBJECT_SRC to be specified
+// as an option and the plugin-types that can be loaded must be restricted to
+// the set specified in kSandboxedPluginTypes.
+bool AllowedToHaveInsecureObjectSrc(
+    int options,
+    const std::vector<std::string>& plugin_types) {
+  if (!(options & OPTIONS_ALLOW_INSECURE_OBJECT_SRC))
+    return false;
+
+  // plugin-types must be specified.
+  if (plugin_types.empty())
+    return false;
+
+  bool only_sandboxed_plugins_specified = true;
+  for (size_t i = 0; i < plugin_types.size(); ++i) {
+    if (!PluginTypeAllowed(plugin_types[i])) {
+      only_sandboxed_plugins_specified = false;

[Mike West, 2014/11/25 13:42:36]

This is probably equally clear if you just return false here and true at the
bottom of the function, rather than creating the local variable.

[raymes, 2014/11/25 13:51:05]

Done.

+      break;
+    }
+  }
+
+  return only_sandboxed_plugins_specified;
+}
+
 }  //  namespace
 
 bool ContentSecurityPolicyIsLegal(const std::string& policy) {
   // We block these characters to prevent HTTP header injection when
   // representing the content security policy as an HTTP header.
   const char kBadChars[] = {',', '\r', '\n', '\0'};
 
   return policy.find_first_of(kBadChars, 0, arraysize(kBadChars)) ==
       std::string::npos;
 }
 
 bool ContentSecurityPolicyIsSecure(const std::string& policy,
-                                   Manifest::Type type) {
+                                   int options) {
   // See http://www.w3.org/TR/CSP/#parse-a-csp-policy for parsing algorithm.
   std::vector<std::string> directives;
   base::SplitString(policy, ';', &directives);
 
   DirectiveStatus default_src_status(kDefaultSrc);
   DirectiveStatus script_src_status(kScriptSrc);
   DirectiveStatus object_src_status(kObjectSrc);
 
+  std::vector<std::string> plugin_types;
+
   for (size_t i = 0; i < directives.size(); ++i) {
     std::string& input = directives[i];
     base::StringTokenizer tokenizer(input, " \t\r\n");
     if (!tokenizer.GetNext())
       continue;
 
     std::string directive_name = tokenizer.token();
     base::StringToLowerASCII(&directive_name);
 
-    if (UpdateStatus(directive_name, tokenizer, &default_src_status, type))
+    if (UpdateStatus(directive_name, tokenizer, &default_src_status, options))
       continue;
-    if (UpdateStatus(directive_name, tokenizer, &script_src_status, type))
+    if (UpdateStatus(directive_name, tokenizer, &script_src_status, options))
       continue;
-    if (UpdateStatus(directive_name, tokenizer, &object_src_status, type))
+    if (UpdateStatus(directive_name, tokenizer, &object_src_status, options))
+      continue;
+    if (ParsePluginTypes(directive_name, tokenizer, &plugin_types))
       continue;
   }
 
   if (script_src_status.seen_in_policy && !script_src_status.is_secure)
     return false;
 
-  if (object_src_status.seen_in_policy && !object_src_status.is_secure)
-    return false;
+  if (object_src_status.seen_in_policy && !object_src_status.is_secure) {
+    // Note that this does not fully check the object-src source list for
+    // validity but Blink will do this anyway.
+    if (!AllowedToHaveInsecureObjectSrc(options, plugin_types))
+      return false;
+  }
 
   if (default_src_status.seen_in_policy && !default_src_status.is_secure) {
     return script_src_status.seen_in_policy &&
            object_src_status.seen_in_policy;
   }
 
   return default_src_status.seen_in_policy ||
       (script_src_status.seen_in_policy && object_src_status.seen_in_policy);
 }
 
@@ skipping 34 matching lines @@
       }
     }
   }
 
   return seen_sandbox;
 }
 
 }  // namespace csp_validator
 
 }  // namespace extensions