Disallow wildcards from matching top-level registry controlled domains during cert validation.

net/base/x509_certificate.cc

Index: net/base/x509_certificate.cc
diff --git a/net/base/x509_certificate.cc b/net/base/x509_certificate.cc
index 915838897e80ac7c5517c19357aa59f706969dbd..451583bfb8082e691626b9cbe0da37fef9fab84a 100644
--- a/net/base/x509_certificate.cc
+++ b/net/base/x509_certificate.cc
@@ -27,6 +27,7 @@
 #include "net/base/net_errors.h"
 #include "net/base/net_util.h"
 #include "net/base/pem_tokenizer.h"
+#include "net/base/registry_controlled_domain.h"
 
 namespace net {
 
@@ -507,17 +508,36 @@ bool X509Certificate::VerifyHostname(
   // |reference_domain| is the remainder of |host| after the leading host
   // component is stripped off, but includes the leading dot e.g.
   // "www.f.com" -> ".f.com".
-  // If there is no meaningful domain part to |host| (e.g. it contains no dots)
-  // then |reference_domain| will be empty.
+  // If there is no meaningful domain part to |host| (e.g. it contains no
+  // dots) then |reference_domain| will be empty.
   base::StringPiece reference_host, reference_domain;
   SplitOnChar(reference_name, '.', &reference_host, &reference_domain);
   bool allow_wildcards = false;
   if (!reference_domain.empty()) {
     DCHECK(reference_domain.starts_with("."));
-    // We required at least 3 components (i.e. 2 dots) as a basic protection
-    // against too-broad wild-carding.
-    // Also we don't attempt wildcard matching on a purely numerical hostname.
-    allow_wildcards = reference_domain.rfind('.') != 0 &&
+
+    // Do not allow wildcards for registry controlled domains, so as to
+    // prevent accepting *.com or *.co.uk as valid presented names. Passing
+    // true for |allow_unknown_registries| so that top-level domains which are
+    // unknown (intranet domains, new TLDs/gTLDs not yet recognized) are
+    // treated as registry-controlled domains. Because the |reference_domain|
+    // must contain at least one name component that is not registry
+    // controlled, this ensures that all reference names have at least three
+    // domain components in order to permit wildcards.
+    size_t registry_length =
+        RegistryControlledDomainService::GetRegistryLength(reference_name,
+                                                           true);
+    // As the |reference_name| was already canonicalized, this should never
+    // happen.
+    CHECK_NE(registry_length, std::string::npos);
+
+    // Subtracting 1 to account for the leading dot in |reference_domain|.
+    bool is_registry_controlled = registry_length != 0 &&
+        registry_length == (reference_domain.size() - 1);
+
+    // Additionally, do not attempt wildcard matching for purely numeric
+    // hostnames.
+    allow_wildcards = !is_registry_controlled &&
         reference_name.find_first_not_of("0123456789.") != std::string::npos;
   }