ssh: Make host and user key pre-checking better

This will prevent crashes in ssh_file for public key types which have no passphrase option although being supported.
Also centralize host key checking to avoid code duplication. This was already done for user keys.

3 files changed, 38 insertions, 33 deletions

diff --git a/lib/ssh/src/ssh_connection_handler.erl b/lib/ssh/src/ssh_connection_handler.erl
index e23df6ceca..7c87591cf2 100644
--- a/lib/ssh/src/ssh_connection_handler.erl
+++ b/lib/ssh/src/ssh_connection_handler.erl
@@ -1685,18 +1685,19 @@ peer_role(client) -> server;
 peer_role(server) -> client.
 
 %%--------------------------------------------------------------------
-available_hkey_algorithms(Role, Options) ->
-    KeyCb = ?GET_OPT(key_cb, Options),
-    case [A || A <- available_hkey_algos(Options),
-               (Role==client) orelse available_host_key(KeyCb, A, Options)
-         ] of
-        
-        [] when Role==client ->
-	    error({shutdown, "No public key algs"});
-
-        [] when Role==server ->
-	    error({shutdown, "No host key available"});
+available_hkey_algorithms(client, Options) ->
+    case available_hkey_algos(Options) of
+        [] ->
+            error({shutdown, "No public key algs"});
+        Algs ->
+	    [atom_to_list(A) || A<-Algs]
+    end;
 
+available_hkey_algorithms(server, Options) ->
+    case [A || A <- available_hkey_algos(Options),
+               is_usable_host_key(A, Options)] of
+        [] ->
+            error({shutdown, "No host key available"});
 	Algs ->
 	    [atom_to_list(A) || A<-Algs]
     end.
@@ -1712,18 +1713,6 @@ available_hkey_algos(Options) ->
     AvailableAndSupported.
 
 
-%% Alg :: atom()
-available_host_key({KeyCb,KeyCbOpts}, Alg, Opts) ->
-    UserOpts = ?GET_OPT(user_options, Opts),
-    case KeyCb:host_key(Alg, [{key_cb_private,KeyCbOpts}|UserOpts]) of
-        {ok,Key} ->
-            %% Check the key - the KeyCb may be a buggy plugin
-            ssh_transport:valid_key_sha_alg(Key, Alg);
-        _ ->
-            false
-    end.
-
-
 send_msg(Msg, State=#data{ssh_params=Ssh0}) when is_tuple(Msg) ->
     {Bytes, Ssh} = ssh_transport:ssh_packet(Msg, Ssh0),
     send_bytes(Bytes, State),
@@ -1843,10 +1832,21 @@ ext_info(_, D0) ->
     D0.
 
 %%%----------------------------------------------------------------
-is_usable_user_pubkey(A, Ssh) ->
-    case ssh_auth:get_public_key(A, Ssh) of
+is_usable_user_pubkey(Alg, Ssh) ->
+    try ssh_auth:get_public_key(Alg, Ssh) of
         {ok,_} -> true;
         _ -> false
+    catch
+        _:_ -> false
+    end.
+
+%%%----------------------------------------------------------------
+is_usable_host_key(Alg, Opts) ->
+    try ssh_transport:get_host_key(Alg, Opts)
+    of
+        _PrivHostKey -> true
+    catch
+        _:_ -> false
     end.
 
 %%%----------------------------------------------------------------
diff --git a/lib/ssh/src/ssh_file.erl b/lib/ssh/src/ssh_file.erl
index 669b0f9be2..c5824b2519 100644
--- a/lib/ssh/src/ssh_file.erl
+++ b/lib/ssh/src/ssh_file.erl
@@ -268,7 +268,8 @@ identity_pass_phrase("rsa-sha2-384"  ) -> rsa_pass_phrase;
 identity_pass_phrase("rsa-sha2-512"  ) -> rsa_pass_phrase;
 identity_pass_phrase("ecdsa-sha2-"++_) -> ecdsa_pass_phrase;
 identity_pass_phrase(P) when is_atom(P) -> 
-    identity_pass_phrase(atom_to_list(P)).
+    identity_pass_phrase(atom_to_list(P));
+identity_pass_phrase(_) -> undefined.
     
 lookup_host_key_fd(Fd, KeyToMatch, Host, KeyType) ->
     case io:get_line(Fd, '') of
diff --git a/lib/ssh/src/ssh_transport.erl b/lib/ssh/src/ssh_transport.erl
index f49b49b2df..cc3ef46fc2 100644
--- a/lib/ssh/src/ssh_transport.erl
+++ b/lib/ssh/src/ssh_transport.erl
@@ -52,6 +52,7 @@
 	 ssh_packet/2, pack/2,
          valid_key_sha_alg/2,
 	 sha/1, sign/3, verify/5,
+         get_host_key/2,
          call_KeyCb/3]).
 
 -export([dbg_trace/3]).
@@ -432,7 +433,8 @@ key_exchange_first_msg(Kex, Ssh0) when Kex == 'ecdh-sha2-nistp256' ;
 %%% 
 handle_kexdh_init(#ssh_msg_kexdh_init{e = E}, 
 		  Ssh0 = #ssh{algorithms = #alg{kex=Kex,
-                                                hkey=SignAlg} = Algs}) ->
+                                                hkey=SignAlg} = Algs,
+                              opts = Opts}) ->
     %% server
     {G, P} = dh_group(Kex),
     if
@@ -440,7 +442,7 @@ handle_kexdh_init(#ssh_msg_kexdh_init{e = E},
             Sz = dh_bits(Algs),
 	    {Public, Private} = generate_key(dh, [P,G,2*Sz]),
 	    K = compute_key(dh, E, Private, [P,G]),
-	    MyPrivHostKey = get_host_key(Ssh0, SignAlg),
+	    MyPrivHostKey = get_host_key(SignAlg, Opts),
 	    MyPubHostKey = extract_public_key(MyPrivHostKey),
             H = kex_hash(Ssh0, MyPubHostKey, sha(Kex), {E,Public,K}),
             H_SIG = sign(H, sha(SignAlg), MyPrivHostKey),
@@ -579,14 +581,15 @@ handle_kex_dh_gex_init(#ssh_msg_kex_dh_gex_init{e = E},
 		       #ssh{keyex_key = {{Private, Public}, {G, P}},
 			    keyex_info = {Min, Max, NBits},
                             algorithms = #alg{kex=Kex,
-                                              hkey=SignAlg}} = Ssh0) ->
+                                              hkey=SignAlg},
+                            opts = Opts} = Ssh0) ->
     %% server
     if
 	1=<E, E=<(P-1) ->
 	    K = compute_key(dh, E, Private, [P,G]),
 	    if
 		1<K, K<(P-1) ->
-		    MyPrivHostKey = get_host_key(Ssh0, SignAlg),
+		    MyPrivHostKey = get_host_key(SignAlg, Opts),
 		    MyPubHostKey = extract_public_key(MyPrivHostKey),
                     H = kex_hash(Ssh0, MyPubHostKey, sha(Kex), {Min,NBits,Max,P,G,E,Public,K}),
                     H_SIG = sign(H, sha(SignAlg), MyPrivHostKey),
@@ -654,7 +657,8 @@ handle_kex_dh_gex_reply(#ssh_msg_kex_dh_gex_reply{public_host_key = PeerPubHostK
 %%% 
 handle_kex_ecdh_init(#ssh_msg_kex_ecdh_init{q_c = PeerPublic},
 		     Ssh0 = #ssh{algorithms = #alg{kex=Kex,
-                                                   hkey=SignAlg}}) ->
+                                                   hkey=SignAlg},
+                                 opts = Opts}) ->
     %% at server
     Curve = ecdh_curve(Kex),
     {MyPublic, MyPrivate} = generate_key(ecdh, Curve),
@@ -662,7 +666,7 @@ handle_kex_ecdh_init(#ssh_msg_kex_ecdh_init{q_c = PeerPublic},
 	compute_key(ecdh, PeerPublic, MyPrivate, Curve)
     of
 	K ->
-	    MyPrivHostKey = get_host_key(Ssh0, SignAlg),
+	    MyPrivHostKey = get_host_key(SignAlg, Opts),
 	    MyPubHostKey = extract_public_key(MyPrivHostKey),
             H = kex_hash(Ssh0, MyPubHostKey, sha(Curve), {PeerPublic, MyPublic, K}),
             H_SIG = sign(H, sha(SignAlg), MyPrivHostKey),
@@ -778,7 +782,7 @@ sid(#ssh{session_id = Id},        _) -> Id.
 %%
 %% The host key should be read from storage
 %%
-get_host_key(#ssh{opts=Opts}, SignAlg) ->
+get_host_key(SignAlg, Opts) ->
     case call_KeyCb(host_key, [SignAlg], Opts) of
 	{ok, PrivHostKey} ->
             %% Check the key - the KeyCb may be a buggy plugin