Remove unsupported algorithms from list of defaults at run time and

remove ifdef and distinct settings for OPENSSL=no case.

This will make things much simpler for -portable where the exact set
of algos depends on the configuration of both OpenSSH and the libcrypto
it's linked against (if any).  ok djm@

1 files changed, 34 insertions, 19 deletions

diff --git a/usr.bin/ssh/readconf.c b/usr.bin/ssh/readconf.c
index 1ed98ec1025..ed550277fec 100644
--- a/usr.bin/ssh/readconf.c
+++ b/usr.bin/ssh/readconf.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: readconf.c,v 1.319 2019/12/21 02:19:13 djm Exp $ */
+/* $OpenBSD: readconf.c,v 1.320 2020/01/23 02:46:49 dtucker Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -300,6 +300,16 @@ static struct {
 	{ NULL, oBadOption }
 };
 
+static char *kex_default_pk_alg_filtered;
+
+const char *
+kex_default_pk_alg(void)
+{
+	if (kex_default_pk_alg_filtered == NULL)
+		fatal("kex_default_pk_alg not initialized.");
+	return kex_default_pk_alg_filtered;
+}
+
 /*
  * Adds a local TCP/IP port forward to options.  Never returns if there is an
  * error.
@@ -1989,6 +1999,7 @@ void
 fill_default_options(Options * options)
 {
 	char *all_cipher, *all_mac, *all_kex, *all_key, *all_sig;
+	char *def_cipher, *def_mac, *def_kex, *def_key, *def_sig;
 	int r;
 
 	if (options->forward_agent == -1)
@@ -2146,24 +2157,35 @@ fill_default_options(Options * options)
 	all_kex = kex_alg_list(',');
 	all_key = sshkey_alg_list(0, 0, 1, ',');
 	all_sig = sshkey_alg_list(0, 1, 1, ',');
+	/* remove unsupported algos from default lists */
+	def_cipher = match_filter_whitelist(KEX_CLIENT_ENCRYPT, all_cipher);
+	def_mac = match_filter_whitelist(KEX_CLIENT_MAC, all_mac);
+	def_kex = match_filter_whitelist(KEX_CLIENT_KEX, all_kex);
+	def_key = match_filter_whitelist(KEX_DEFAULT_PK_ALG, all_key);
+	def_sig = match_filter_whitelist(SSH_ALLOWED_CA_SIGALGS, all_sig);
 #define ASSEMBLE(what, defaults, all) \
 	do { \
 		if ((r = kex_assemble_names(&options->what, \
 		    defaults, all)) != 0) \
 			fatal("%s: %s: %s", __func__, #what, ssh_err(r)); \
 	} while (0)
-	ASSEMBLE(ciphers, KEX_CLIENT_ENCRYPT, all_cipher);
-	ASSEMBLE(macs, KEX_CLIENT_MAC, all_mac);
-	ASSEMBLE(kex_algorithms, KEX_CLIENT_KEX, all_kex);
-	ASSEMBLE(hostbased_key_types, KEX_DEFAULT_PK_ALG, all_key);
-	ASSEMBLE(pubkey_key_types, KEX_DEFAULT_PK_ALG, all_key);
-	ASSEMBLE(ca_sign_algorithms, SSH_ALLOWED_CA_SIGALGS, all_sig);
+	ASSEMBLE(ciphers, def_cipher, all_cipher);
+	ASSEMBLE(macs, def_mac, all_mac);
+	ASSEMBLE(kex_algorithms, def_kex, all_kex);
+	ASSEMBLE(hostbased_key_types, def_key, all_key);
+	ASSEMBLE(pubkey_key_types, def_key, all_key);
+	ASSEMBLE(ca_sign_algorithms, def_sig, all_sig);
 #undef ASSEMBLE
 	free(all_cipher);
 	free(all_mac);
 	free(all_kex);
 	free(all_key);
 	free(all_sig);
+	free(def_cipher);
+	free(def_mac);
+	free(def_kex);
+	kex_default_pk_alg_filtered = def_key; /* save for later use */
+	free(def_sig);
 
 #define CLEAR_ON_NONE(v) \
 	do { \
@@ -2613,14 +2635,7 @@ void
 dump_client_config(Options *o, const char *host)
 {
 	int i;
-	char buf[8], *all_key;
-
-	/* This is normally prepared in ssh_kex2 */
-	all_key = sshkey_alg_list(0, 0, 1, ',');
-	if (kex_assemble_names( &o->hostkeyalgorithms,
-	    KEX_DEFAULT_PK_ALG, all_key) != 0)
-		fatal("%s: kex_assemble_names failed", __func__);
-	free(all_key);
+	char buf[8];
 
 	/* Most interesting options first: user, host, port */
 	dump_cfg_string(oUser, o->user);
@@ -2677,7 +2692,7 @@ dump_client_config(Options *o, const char *host)
 	/* String options */
 	dump_cfg_string(oBindAddress, o->bind_address);
 	dump_cfg_string(oBindInterface, o->bind_interface);
-	dump_cfg_string(oCiphers, o->ciphers ? o->ciphers : KEX_CLIENT_ENCRYPT);
+	dump_cfg_string(oCiphers, o->ciphers);
 	dump_cfg_string(oControlPath, o->control_path);
 	dump_cfg_string(oHostKeyAlgorithms, o->hostkeyalgorithms);
 	dump_cfg_string(oHostKeyAlias, o->host_key_alias);
@@ -2685,12 +2700,12 @@ dump_client_config(Options *o, const char *host)
 	dump_cfg_string(oIdentityAgent, o->identity_agent);
 	dump_cfg_string(oIgnoreUnknown, o->ignored_unknown);
 	dump_cfg_string(oKbdInteractiveDevices, o->kbd_interactive_devices);
-	dump_cfg_string(oKexAlgorithms, o->kex_algorithms ? o->kex_algorithms : KEX_CLIENT_KEX);
-	dump_cfg_string(oCASignatureAlgorithms, o->ca_sign_algorithms ? o->ca_sign_algorithms : SSH_ALLOWED_CA_SIGALGS);
+	dump_cfg_string(oKexAlgorithms, o->kex_algorithms);
+	dump_cfg_string(oCASignatureAlgorithms, o->ca_sign_algorithms);
 	dump_cfg_string(oLocalCommand, o->local_command);
 	dump_cfg_string(oRemoteCommand, o->remote_command);
 	dump_cfg_string(oLogLevel, log_level_name(o->log_level));
-	dump_cfg_string(oMacs, o->macs ? o->macs : KEX_CLIENT_MAC);
+	dump_cfg_string(oMacs, o->macs);
 #ifdef ENABLE_PKCS11
 	dump_cfg_string(oPKCS11Provider, o->pkcs11_provider);
 #endif