detect unknown ciphers when parsing TLS session

2 files changed, 33 insertions, 4 deletions

diff --git a/src/lib/tls/tls_session.cpp b/src/lib/tls/tls_session.cpp
index 28ee8e9ab..8eb03712b 100644
--- a/src/lib/tls/tls_session.cpp
+++ b/src/lib/tls/tls_session.cpp
@@ -69,6 +69,7 @@ Session::Session(const uint8_t ber[], size_t ber_len)
    size_t srtp_profile = 0;
    size_t fragment_size = 0;
    size_t compression_method = 0;
+   uint16_t ciphersuite_code = 0;
 
    BER_Decoder(ber, ber_len)
       .start_sequence()
@@ -79,7 +80,7 @@ Session::Session(const uint8_t ber[], size_t ber_len)
         .decode_integer_type(minor_version)
         .decode(m_identifier, ASN1_Type::OctetString)
         .decode(m_session_ticket, ASN1_Type::OctetString)
-        .decode_integer_type(m_ciphersuite)
+        .decode_integer_type(ciphersuite_code)
         .decode_integer_type(compression_method)
         .decode_integer_type(side_code)
         .decode_integer_type(fragment_size)
@@ -113,6 +114,13 @@ Session::Session(const uint8_t ber[], size_t ber_len)
                            " no longer supported");
       }
 
+   if(!Ciphersuite::by_id(ciphersuite_code))
+      {
+      throw Decoding_Error("Serialized TLS session contains unknown cipher suite "
+                           "(" + std::to_string(ciphersuite_code) + ")");
+      }
+
+   m_ciphersuite = ciphersuite_code;
    m_version = Protocol_Version(major_version, minor_version);
    m_start_time = std::chrono::system_clock::from_time_t(start_time);
    m_connection_side = static_cast<Connection_Side>(side_code);
diff --git a/src/tests/test_tls.cpp b/src/tests/test_tls.cpp
index 83caca7ba..c6be40325 100644
--- a/src/tests/test_tls.cpp
+++ b/src/tests/test_tls.cpp
@@ -37,13 +37,13 @@ class TLS_Session_Tests final : public Test
          Botan::secure_vector<uint8_t> default_der = default_session.DER_encode();
 
          result.test_gte("Encoded default session has size", default_der.size(), 0);
-
-         Botan::TLS::Session decoded_default(default_der.data(), default_der.size());
+         result.test_throws("Encoded default session cannot be read",
+                            [&] { Botan::TLS::Session{default_der.data(), default_der.size()}; });
 
          Botan::TLS::Session session(std::vector<uint8_t>{0xAA, 0xBB},
                                      Botan::secure_vector<uint8_t>{0xCC, 0xDD},
                                      Botan::TLS::Protocol_Version::TLS_V12,
-                                     0xFE0F,
+                                     0xC02F,
                                      Botan::TLS::CLIENT,
                                      true,
                                      false,
@@ -56,6 +56,10 @@ class TLS_Session_Tests final : public Test
          Botan::TLS::Session session_from_pem(pem);
          result.test_eq("Roundtrip from pem", session.DER_encode(), session_from_pem.DER_encode());
 
+         const auto der = session.DER_encode();
+         Botan::TLS::Session session_from_der(der.data(), der.size());
+         result.test_eq("Roundtrip from der", session.DER_encode(), session_from_der.DER_encode());
+
          const Botan::SymmetricKey key("ABCDEF");
          const std::vector<uint8_t> ctext1 = session.encrypt(key, Test::rng());
          const std::vector<uint8_t> ctext2 = session.encrypt(key, Test::rng());
@@ -80,6 +84,23 @@ class TLS_Session_Tests final : public Test
 
          result.test_eq("Only randomness comes from RNG", ctextf1, ctextf2);
 
+         Botan::TLS::Session session2(std::vector<uint8_t>{0xAA, 0xCC},
+                                     Botan::secure_vector<uint8_t>{0xCC, 0xEE},
+                                     Botan::TLS::Protocol_Version::TLS_V12,
+                                     0xBAAD, // cipher suite does not exist
+                                     Botan::TLS::CLIENT,
+                                     true,
+                                     false,
+                                     std::vector<Botan::X509_Certificate>(),
+                                     std::vector<uint8_t>(),
+                                     Botan::TLS::Server_Information("server"),
+                                     0x0000);
+         const std::string pem_with_unknown_ciphersuite = session2.PEM_encode();
+
+         result.test_throws("unknown ciphersuite during session parsing",
+                            "Serialized TLS session contains unknown cipher suite (47789)",
+                            [&] { Botan::TLS::Session{pem_with_unknown_ciphersuite}; });
+
          return {result};
          }
    };