Fix TLS signature algorithm intolerance

GH #1708

4 files changed, 33 insertions, 17 deletions

diff --git a/src/lib/tls/tls_algos.cpp b/src/lib/tls/tls_algos.cpp
index 9c3c2d9f8..9501cfdfb 100644
--- a/src/lib/tls/tls_algos.cpp
+++ b/src/lib/tls/tls_algos.cpp
@@ -223,7 +223,7 @@ std::string hash_function_of_scheme(Signature_Scheme scheme)
          return "";
       }
 
-   throw Invalid_State("Unknown signature algorithm enum");
+   throw Invalid_State("hash_function_of_scheme: Unknown signature algorithm enum");
    }
 
 const std::vector<Signature_Scheme>& all_signature_schemes()
@@ -323,7 +323,7 @@ std::string signature_algorithm_of_scheme(Signature_Scheme scheme)
          return "";
       }
 
-   throw Invalid_State("Unknown signature algorithm enum");
+   throw Invalid_State("signature_algorithm_of_scheme: Unknown signature algorithm enum");
    }
 
 std::string sig_scheme_to_string(Signature_Scheme scheme)
@@ -373,7 +373,7 @@ std::string sig_scheme_to_string(Signature_Scheme scheme)
          return "";
       }
 
-   throw Invalid_State("Unknown signature algorithm enum");
+   throw Invalid_State("sig_scheme_to_string: Unknown signature algorithm enum");
    }
 
 std::string padding_string_for_scheme(Signature_Scheme scheme)
@@ -418,7 +418,7 @@ std::string padding_string_for_scheme(Signature_Scheme scheme)
          return "";
       }
 
-   throw Invalid_State("Unknown signature algorithm enum");
+   throw Invalid_State("padding_string_for_scheme: Unknown signature algorithm enum");
    }
 
 }
diff --git a/src/lib/tls/tls_extensions.h b/src/lib/tls/tls_extensions.h
index ce7e2e94b..98856b951 100644
--- a/src/lib/tls/tls_extensions.h
+++ b/src/lib/tls/tls_extensions.h
@@ -71,7 +71,7 @@ class BOTAN_UNSTABLE_API Extension
 /**
 * Server Name Indicator extension (RFC 3546)
 */
-class Server_Name_Indicator final : public Extension
+class BOTAN_UNSTABLE_API Server_Name_Indicator final : public Extension
    {
    public:
       static Handshake_Extension_Type static_type()
@@ -98,7 +98,7 @@ class Server_Name_Indicator final : public Extension
 /**
 * SRP identifier extension (RFC 5054)
 */
-class SRP_Identifier final : public Extension
+class BOTAN_UNSTABLE_API SRP_Identifier final : public Extension
    {
    public:
       static Handshake_Extension_Type static_type()
@@ -125,7 +125,7 @@ class SRP_Identifier final : public Extension
 /**
 * Renegotiation Indication Extension (RFC 5746)
 */
-class Renegotiation_Extension final : public Extension
+class BOTAN_UNSTABLE_API Renegotiation_Extension final : public Extension
    {
    public:
       static Handshake_Extension_Type static_type()
@@ -154,7 +154,7 @@ class Renegotiation_Extension final : public Extension
 /**
 * ALPN (RFC 7301)
 */
-class Application_Layer_Protocol_Notification final : public Extension
+class BOTAN_UNSTABLE_API Application_Layer_Protocol_Notification final : public Extension
    {
    public:
       static Handshake_Extension_Type static_type() { return TLSEXT_ALPN; }
@@ -190,7 +190,7 @@ class Application_Layer_Protocol_Notification final : public Extension
 /**
 * Session Ticket Extension (RFC 5077)
 */
-class Session_Ticket final : public Extension
+class BOTAN_UNSTABLE_API Session_Ticket final : public Extension
    {
    public:
       static Handshake_Extension_Type static_type()
@@ -230,7 +230,7 @@ class Session_Ticket final : public Extension
 /**
 * Supported Groups Extension (RFC 7919)
 */
-class Supported_Groups final : public Extension
+class BOTAN_UNSTABLE_API Supported_Groups final : public Extension
    {
    public:
       static Handshake_Extension_Type static_type()
@@ -259,7 +259,7 @@ class Supported_Groups final : public Extension
 /**
 * Supported Point Formats Extension (RFC 4492)
 */
-class Supported_Point_Formats final : public Extension
+class BOTAN_UNSTABLE_API Supported_Point_Formats final : public Extension
    {
    public:
       enum ECPointFormat : uint8_t {
@@ -292,7 +292,7 @@ class Supported_Point_Formats final : public Extension
 /**
 * Signature Algorithms Extension for TLS 1.2 (RFC 5246)
 */
-class Signature_Algorithms final : public Extension
+class BOTAN_UNSTABLE_API Signature_Algorithms final : public Extension
    {
    public:
       static Handshake_Extension_Type static_type()
@@ -318,7 +318,7 @@ class Signature_Algorithms final : public Extension
 /**
 * Used to indicate SRTP algorithms for DTLS (RFC 5764)
 */
-class SRTP_Protection_Profiles final : public Extension
+class BOTAN_UNSTABLE_API SRTP_Protection_Profiles final : public Extension
    {
    public:
       static Handshake_Extension_Type static_type()
@@ -344,7 +344,7 @@ class SRTP_Protection_Profiles final : public Extension
 /**
 * Extended Master Secret Extension (RFC 7627)
 */
-class Extended_Master_Secret final : public Extension
+class BOTAN_UNSTABLE_API Extended_Master_Secret final : public Extension
    {
    public:
       static Handshake_Extension_Type static_type()
@@ -364,7 +364,7 @@ class Extended_Master_Secret final : public Extension
 /**
 * Encrypt-then-MAC Extension (RFC 7366)
 */
-class Encrypt_then_MAC final : public Extension
+class BOTAN_UNSTABLE_API Encrypt_then_MAC final : public Extension
    {
    public:
       static Handshake_Extension_Type static_type()
@@ -384,7 +384,7 @@ class Encrypt_then_MAC final : public Extension
 /**
 * Certificate Status Request (RFC 6066)
 */
-class Certificate_Status_Request final : public Extension
+class BOTAN_UNSTABLE_API Certificate_Status_Request final : public Extension
    {
    public:
       static Handshake_Extension_Type static_type()
diff --git a/src/lib/tls/tls_handshake_state.cpp b/src/lib/tls/tls_handshake_state.cpp
index d113276b3..a9c7514c1 100644
--- a/src/lib/tls/tls_handshake_state.cpp
+++ b/src/lib/tls/tls_handshake_state.cpp
@@ -398,6 +398,11 @@ Handshake_State::choose_sig_format(const Private_Key& key,
 
       for(Signature_Scheme scheme : schemes)
          {
+         if(signature_scheme_is_known(scheme) == false)
+            {
+            continue;
+            }
+
          if(signature_algorithm_of_scheme(scheme) == sig_algo)
             {
             if(std::find(allowed.begin(), allowed.end(), scheme) != allowed.end())
@@ -451,7 +456,8 @@ bool supported_algos_include(
    {
    for(Signature_Scheme scheme : schemes)
       {
-      if(hash_function_of_scheme(scheme) == hash_type &&
+      if(signature_scheme_is_known(scheme) &&
+         hash_function_of_scheme(scheme) == hash_type &&
          signature_algorithm_of_scheme(scheme) == key_type)
          {
          return true;
diff --git a/src/tests/unit_tls.cpp b/src/tests/unit_tls.cpp
index a26c6e9f7..f60e44a14 100644
--- a/src/tests/unit_tls.cpp
+++ b/src/tests/unit_tls.cpp
@@ -391,6 +391,16 @@ class TLS_Handshake_Test final
             void tls_modify_extensions(Botan::TLS::Extensions& extn, Botan::TLS::Connection_Side which_side) override
                {
                extn.add(new Test_Extension(which_side));
+
+               // Insert an unsupported signature scheme as highest prio, to ensure we are tolerant of this
+               if(auto sig_algs = extn.get<Botan::TLS::Signature_Algorithms>())
+                  {
+                  std::vector<Botan::TLS::Signature_Scheme> schemes = sig_algs->supported_schemes();
+                  // 0x0301 is RSA PKCS1/SHA-224, which is not supported anymore
+                  schemes.insert(schemes.begin(), static_cast<Botan::TLS::Signature_Scheme>(0x0301));
+                  // This replaces the previous extension value
+                  extn.add(new Botan::TLS::Signature_Algorithms(schemes));
+                  }
                }
 
             void tls_examine_extensions(const Botan::TLS::Extensions& extn, Botan::TLS::Connection_Side which_side) override