Lock down the registration of blob:chrome-extension:// URLs

content/browser/child_process_security_policy_impl.cc

Index: content/browser/child_process_security_policy_impl.cc
diff --git a/content/browser/child_process_security_policy_impl.cc b/content/browser/child_process_security_policy_impl.cc
index db3fb1b3a7d08a2bb529a5db43c0569830973605..4a50e01253201e5778fa2775624e905336786919 100644
--- a/content/browser/child_process_security_policy_impl.cc
+++ b/content/browser/child_process_security_policy_impl.cc
@@ -202,6 +202,8 @@ class ChildProcessSecurityPolicyImpl::SecurityState {
 
   // Determine whether permission has been granted to commit |url|.
   bool CanCommitURL(const GURL& url) {
+    DCHECK(!url.SchemeIsBlob() && !url.SchemeIsFileSystem())
+        << "inner_url extraction should be done already.";
     // Having permission to a scheme implies permission to all of its URLs.
     SchemeMap::const_iterator scheme_judgment(
         scheme_policy_.find(url.scheme()));
@@ -326,6 +328,10 @@ ChildProcessSecurityPolicyImpl::ChildProcessSecurityPolicyImpl() {
   RegisterWebSafeScheme(url::kFtpScheme);
   RegisterWebSafeScheme(url::kDataScheme);
   RegisterWebSafeScheme("feed");
+
+  // TODO(nick): blob: and filesystem: schemes embed other origins,
+  // so we should not treat them as web safe. Remove callers of
+  // IsWebSafeScheme(), and then eliminate the next two lines.

[Charlie Reis, 2016/09/29 21:39:37]

Let's list https://crbug.com/651534 here, too.

[ncarter (slow), 2016/09/29 22:04:02]

Done.

   RegisterWebSafeScheme(url::kBlobScheme);
   RegisterWebSafeScheme(url::kFileSystemScheme);
 
@@ -338,9 +344,6 @@ ChildProcessSecurityPolicyImpl::ChildProcessSecurityPolicyImpl() {
 }
 
 ChildProcessSecurityPolicyImpl::~ChildProcessSecurityPolicyImpl() {
-  web_safe_schemes_.clear();
-  pseudo_schemes_.clear();
-  security_state_.clear();
 }
 
 // static
@@ -373,25 +376,43 @@ void ChildProcessSecurityPolicyImpl::Remove(int child_id) {
 void ChildProcessSecurityPolicyImpl::RegisterWebSafeScheme(
     const std::string& scheme) {
   base::AutoLock lock(lock_);
-  DCHECK_EQ(0U, web_safe_schemes_.count(scheme)) << "Add schemes at most once.";
+  DCHECK_EQ(0U, schemes_okay_to_request_in_any_process_.count(scheme))
+      << "Add schemes at most once.";
+  DCHECK_EQ(0U, pseudo_schemes_.count(scheme))
+      << "Web-safe implies not pseudo.";
+
+  schemes_okay_to_request_in_any_process_.insert(scheme);
+  schemes_okay_to_commit_in_any_process_.insert(scheme);
+}
+
+void ChildProcessSecurityPolicyImpl::RegisterWebSafeIsolatedScheme(
+    const std::string& scheme,
+    bool always_allow_in_origin_headers) {
+  base::AutoLock lock(lock_);
+  DCHECK_EQ(0U, schemes_okay_to_request_in_any_process_.count(scheme))
+      << "Add schemes at most once.";
   DCHECK_EQ(0U, pseudo_schemes_.count(scheme))
       << "Web-safe implies not pseudo.";
 
-  web_safe_schemes_.insert(scheme);
+  schemes_okay_to_request_in_any_process_.insert(scheme);
+  if (always_allow_in_origin_headers)
+    schemes_okay_to_appear_as_origin_headers_.insert(scheme);
 }
 
 bool ChildProcessSecurityPolicyImpl::IsWebSafeScheme(
     const std::string& scheme) {
   base::AutoLock lock(lock_);
 
-  return base::ContainsKey(web_safe_schemes_, scheme);
+  return base::ContainsKey(schemes_okay_to_request_in_any_process_, scheme);
 }
 
 void ChildProcessSecurityPolicyImpl::RegisterPseudoScheme(
     const std::string& scheme) {
   base::AutoLock lock(lock_);
   DCHECK_EQ(0U, pseudo_schemes_.count(scheme)) << "Add schemes at most once.";
-  DCHECK_EQ(0U, web_safe_schemes_.count(scheme))
+  DCHECK_EQ(0U, schemes_okay_to_request_in_any_process_.count(scheme))
+      << "Pseudo implies not web-safe.";
+  DCHECK_EQ(0U, schemes_okay_to_commit_in_any_process_.count(scheme))
       << "Pseudo implies not web-safe.";
 
   pseudo_schemes_.insert(scheme);
@@ -417,6 +438,10 @@ void ChildProcessSecurityPolicyImpl::GrantRequestURL(
     return;  // Can't grant the capability to request pseudo schemes.
   }
 
+  if (url.SchemeIsBlob() || url.SchemeIsFileSystem()) {
+    return;  // Don't grant blanket access to blob: or filesystem: schemes.
+  }
+
   {
     base::AutoLock lock(lock_);
     SecurityStateMap::iterator state = security_state_.find(child_id);
@@ -606,8 +631,19 @@ bool ChildProcessSecurityPolicyImpl::CanRequestURL(
     return false;
   }
 
-  if (IsMalformedBlobUrl(url))
-    return false;
+  // Blob and filesystem URLs require special treatment, since they embed an
+  // inner origin.
+  if (url.SchemeIsBlob() || url.SchemeIsFileSystem()) {
+    if (IsMalformedBlobUrl(url))
+      return false;
+
+    url::Origin origin(url);
+    return origin.unique() || IsWebSafeScheme(origin.scheme()) ||
+           CanCommitURL(child_id, GURL(origin.Serialize()));
+  }
+
+  if (IsWebSafeScheme(url.scheme()))
+    return true;
 
   // If the process can commit the URL, it can request it.
   if (CanCommitURL(child_id, url))
@@ -627,19 +663,33 @@ bool ChildProcessSecurityPolicyImpl::CanCommitURL(int child_id,
   if (IsPseudoScheme(url.scheme()))
     return base::LowerCaseEqualsASCII(url.spec(), url::kAboutBlankURL);
 
-  if (IsMalformedBlobUrl(url))
-    return false;
+  // Blob and filesystem URLs require special treatment; validate the inner
+  // origin they embed.
+  if (url.SchemeIsBlob() || url.SchemeIsFileSystem()) {
+    if (IsMalformedBlobUrl(url))
+      return false;
 
-  // TODO(creis): Tighten this for Site Isolation, so that a URL from a site
-  // that is isolated can only be committed in a process dedicated to that site.
-  // CanRequestURL should still allow all web-safe schemes. See
-  // https://crbug.com/515309.
-  if (IsWebSafeScheme(url.scheme()))
-    return true;  // The scheme has been white-listed for every child process.
+    url::Origin origin(url);
+    return origin.unique() || CanCommitURL(child_id, GURL(origin.Serialize()));
+  }
 
   {
     base::AutoLock lock(lock_);
 
+    // Most schemes can commit in any process. Note that we check
+    // schemes_okay_to_commit_in_any_process_ here, which is stricter than
+    // IsWebSafeScheme().
+    //
+    // TODO(creis, nick): https://crbug.com/515309: in generalized Site
+    // Isolation and/or --site-per-process, there will be no such thing as a
+    // scheme that is okay to commit in any process. Instead, an URL from a site
+    // that is isolated may only be committed in a process dedicated to that
+    // site, so CanCommitURL will need to rely on explicit, per-process grants.
+    // Note how today, even with extension isolation, the line below does not
+    // enforce that http pages cannot commit in an extension process.

[Charlie Reis, 2016/09/29 21:39:37]

Good point.

[ncarter (slow), 2016/09/29 22:04:02]

Done.

+    if (base::ContainsKey(schemes_okay_to_commit_in_any_process_, url.scheme()))
+      return true;
+
     SecurityStateMap::iterator state = security_state_.find(child_id);
     if (state == security_state_.end())
       return false;
@@ -662,7 +712,21 @@ bool ChildProcessSecurityPolicyImpl::CanSetAsOriginHeader(int child_id,
     return true;
   }
 
-  return CanCommitURL(child_id, url);
+  // If this process can commit |url|, it can use |url| as an origin for
+  // outbound requests.
+  if (CanCommitURL(child_id, url))
+    return true;
+
+  // Allow schemes which may come from scripts executing in isolated worlds;
+  // XHRs issued by such scripts reflect the script origin rather than the
+  // document origin.
+  {
+    base::AutoLock lock(lock_);
+    if (base::ContainsKey(schemes_okay_to_appear_as_origin_headers_,

[Charlie Reis, 2016/09/29 21:39:37]

Now I see why Joel's CanSetAsOriginHeader refactor proved useful here.  :)  This
set's name wouldn't have made as much sense if we consulted it from
CanCommitURL.

[ncarter (slow), 2016/09/29 22:04:02]

Yeah, well-timed ... except that it'll complicate the merge.

+                          url.scheme()))
+      return true;
+  }
+  return false;
 }
 
 bool ChildProcessSecurityPolicyImpl::CanReadFile(int child_id,