SSH: Work around issue with dynamic_cast.

It has been observed that on MacOs, a dynamic_cast from
Botan::Public_Key to Botan::RSA_PublicKey reproducibly fails even though
it should definitely succeed. This happens with both gcc and clang on
different Macs, but on no other platform. The problem could not be
reproduced with an example project.
The workaround is to move the allocation of the respective object from
the client side to the Botan library itself. In addition, the following
actions were taken to guard against similar problems in the future:
    - Also move to Botan the allocations of all other objects that are
potentially dynamically cast.
    - Use shared pointers for these objects, so the deallocation also
happens inside Botan.

Change-Id: Ie595a56a239a41e2629b6ff631de59910b8244dd
Reviewed-by: Eike Ziller <eike.ziller@digia.com>

1 files changed, 9 insertions, 14 deletions

diff --git a/src/libs/ssh/sshkeyexchange.cpp b/src/libs/ssh/sshkeyexchange.cpp
index c11201c47c..0c0fea6215 100644
--- a/src/libs/ssh/sshkeyexchange.cpp
+++ b/src/libs/ssh/sshkeyexchange.cpp
@@ -136,8 +136,7 @@ bool SshKeyExchange::sendDhInitPacket(const SshIncomingPacket &serverKexInit)
         kexInitParams.compressionAlgorithmsServerToClient.names);
 
     AutoSeeded_RNG rng;
-    m_dhKey.reset(new DH_PrivateKey(rng,
-        DL_Group(botanKeyExchangeAlgoName(keyAlgo))));
+    m_dhKey = createDhPrivateKey(rng, DL_Group(botanKeyExchangeAlgoName(keyAlgo)));
 
     m_serverKexInitPayload = serverKexInit.payLoad();
     m_sendFacility.sendKeyDhInitPacket(m_dhKey->get_y());
@@ -184,28 +183,24 @@ void SshKeyExchange::sendNewKeysPacket(const SshIncomingPacket &dhReply,
     printData("H", m_h);
 #endif // CREATOR_SSH_DEBUG
 
-    QScopedPointer<Public_Key> sigKey;
-    QScopedPointer<PK_Verifier> verifier;
+    QSharedPointer<Public_Key> publicKey;
+    QByteArray algorithm;
     if (m_serverHostKeyAlgo == SshCapabilities::PubKeyDss) {
         const DL_Group group(reply.parameters.at(0), reply.parameters.at(1),
             reply.parameters.at(2));
-        DSA_PublicKey * const dsaKey
-            = new DSA_PublicKey(group, reply.parameters.at(3));
-        sigKey.reset(dsaKey);
-        verifier.reset(new PK_Verifier(*dsaKey, botanEmsaAlgoName(SshCapabilities::PubKeyDss)));
+        publicKey = createDsaPublicKey(group, reply.parameters.at(3));
+        algorithm = SshCapabilities::PubKeyDss;
     } else if (m_serverHostKeyAlgo == SshCapabilities::PubKeyRsa) {
-        RSA_PublicKey * const rsaKey
-            = new RSA_PublicKey(reply.parameters.at(1), reply.parameters.at(0));
-        sigKey.reset(rsaKey);
-        verifier.reset(new PK_Verifier(*rsaKey, botanEmsaAlgoName(SshCapabilities::PubKeyRsa)));
+        publicKey = createRsaPublicKey(reply.parameters.at(1), reply.parameters.at(0));
+        algorithm = SshCapabilities::PubKeyRsa;
     } else {
         Q_ASSERT(!"Impossible: Neither DSS nor RSA!");
     }
     const byte * const botanH = convertByteArray(m_h);
     const Botan::byte * const botanSig
         = convertByteArray(reply.signatureBlob);
-    if (!verifier->verify_message(botanH, m_h.size(), botanSig,
-        reply.signatureBlob.size())) {
+    if (!PK_Verifier(*publicKey, botanEmsaAlgoName(algorithm)).verify_message(botanH, m_h.size(),
+            botanSig, reply.signatureBlob.size())) {
         throw SSH_SERVER_EXCEPTION(SSH_DISCONNECT_KEY_EXCHANGE_FAILED,
             "Invalid signature in SSH_MSG_KEXDH_REPLY packet.");
     }