Do not use HTTP/2 without adequate security.

net/socket/ssl_client_socket_nss.cc

Index: net/socket/ssl_client_socket_nss.cc
diff --git a/net/socket/ssl_client_socket_nss.cc b/net/socket/ssl_client_socket_nss.cc
index 3651e8d62466696169433993af5f4cd92d62b67b..a209dd3e6fb66e3f566a4ddc9bb179b2a31df7a9 100644
--- a/net/socket/ssl_client_socket_nss.cc
+++ b/net/socket/ssl_client_socket_nss.cc
@@ -973,8 +973,26 @@ bool SSLClientSocketNSS::Core::Init(PRFileDesc* socket,
   SECStatus rv = SECSuccess;
 
   if (!ssl_config_.next_protos.empty()) {
-    std::vector<uint8_t> wire_protos =
-        SerializeNextProtos(ssl_config_.next_protos);
+    DCHECK(NSS_IsInitialized());
+    const std::vector<uint16> cipher_suites =
+        GetNSSDefaultEnabledCipherSuites();
+    std::vector<uint16> implemented_enabled_cipher_suites;
+    // TODO(bnc): SSL_CipherPrefGet uses linear search.  Consider rewriting it
+    // using binary search, or merging the for cycle that applies
+    // disabled_cipher_suites in SSLClientSocketNSS::InitializeSSLOptions() with
+    // the cycle below to avoid using it.
+    for (uint16 cipher : cipher_suites) {
+      PRBool enabled = PR_FALSE;
+      if (PK11_TokenExists(cipher) &&

[davidben, 2014/12/12 19:45:36]

We talked about this out-of-band, but to publish this comment: PK11_TokenExists
takes a CK_MECHANISM_TYPE, not a cipher suite. NSS has to do other work to
translate between a cipher suite to the mechanisms it needs. Unfortunately, that
seems to happen pretty late.

Probably simplest to only check PK11_TokenExists for AES-GCM. That's the only
case that varies that we care about.

[Bence, 2014/12/12 20:21:33]

Done.

+          SSL_CipherPrefGet(nss_fd_, cipher, &enabled) == SECSuccess &&
+          enabled) {
+        implemented_enabled_cipher_suites.push_back(cipher);
+      }
+    }
+    std::vector<uint8_t> wire_protos = SerializeNextProtos(
+        ssl_config_.next_protos,
+        IsSecurityAdequateForHTTP2(ssl_config_,
+                                   implemented_enabled_cipher_suites));
     rv = SSL_SetNextProtoNego(
         nss_fd_, wire_protos.empty() ? NULL : &wire_protos[0],
         wire_protos.size());