upstream: 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@ OpenBSD-Commit-ID: e0116d0183dcafc7a9c40ba5fe9127805c5dfdd2
openssh · Jan 23, 2020 · c4b3a12 · c4b3a12
1 parent 56cffcc
commit c4b3a12
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diff --git a/clientloop.c b/clientloop.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: clientloop.c,v 1.330 2019/12/21 02:19:13 djm Exp $ */
+/* $OpenBSD: clientloop.c,v 1.331 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
@@ -2046,8 +2046,7 @@ static int
 key_accepted_by_hostkeyalgs(const struct sshkey *key)
 {
 	const char *ktype = sshkey_ssh_name(key);
-	const char *hostkeyalgs = options.hostkeyalgorithms != NULL ?
-	    options.hostkeyalgorithms : KEX_DEFAULT_PK_ALG;
+	const char *hostkeyalgs = options.hostkeyalgorithms;
 
 	if (key == NULL || key->type == KEY_UNSPEC)
 		return 0;

diff --git a/myproposal.h b/myproposal.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: myproposal.h,v 1.65 2020/01/22 04:58:23 tedu Exp $ */
+/* $OpenBSD: myproposal.h,v 1.66 2020/01/23 02:46:49 dtucker Exp $ */
 
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
@@ -24,110 +24,47 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#ifdef WITH_OPENSSL
-#include <openssl/opensslv.h>
-#endif
-
-/* conditional algorithm support */
-
-#ifdef OPENSSL_HAS_ECC
-# ifdef OPENSSL_HAS_NISTP521
-#  define KEX_ECDH_METHODS \
+#define KEX_SERVER_KEX	\
+	"curve25519-sha256," \
+	"curve25519-sha256@libssh.org," \
 	"ecdh-sha2-nistp256," \
 	"ecdh-sha2-nistp384," \
-	"ecdh-sha2-nistp521,"
-#  define HOSTKEY_ECDSA_CERT_METHODS \
-	"ecdsa-sha2-nistp256-cert-v01@openssh.com," \
-	"ecdsa-sha2-nistp384-cert-v01@openssh.com," \
-	"ecdsa-sha2-nistp521-cert-v01@openssh.com," \
-	"sk-ecdsa-sha2-nistp256-cert-v01@openssh.com,"
-#  define HOSTKEY_ECDSA_METHODS \
-	"ecdsa-sha2-nistp256," \
-	"ecdsa-sha2-nistp384," \
-	"ecdsa-sha2-nistp521," \
-	"sk-ecdsa-sha2-nistp256@openssh.com,"
-# else /* OPENSSL_HAS_NISTP521 */
-#  define KEX_ECDH_METHODS \
-	"ecdh-sha2-nistp256," \
-	"ecdh-sha2-nistp384,"
-#  define HOSTKEY_ECDSA_CERT_METHODS \
-	"ecdsa-sha2-nistp256-cert-v01@openssh.com," \
-	"ecdsa-sha2-nistp384-cert-v01@openssh.com," \
-	"sk-ecdsa-sha2-nistp256-cert-v01@openssh.com,"
-#  define HOSTKEY_ECDSA_METHODS \
-	"ecdsa-sha2-nistp256," \
-	"ecdsa-sha2-nistp384," \
-	"sk-ecdsa-sha2-nistp256@openssh.com,"
-# endif /* OPENSSL_HAS_NISTP521 */
-#else /* OPENSSL_HAS_ECC */
-# define KEX_ECDH_METHODS
-# define HOSTKEY_ECDSA_CERT_METHODS
-# define HOSTKEY_ECDSA_METHODS
-#endif /* OPENSSL_HAS_ECC */
-
-#ifdef OPENSSL_HAVE_EVPGCM
-# define AESGCM_CIPHER_MODES \
-	",aes128-gcm@openssh.com,aes256-gcm@openssh.com"
-#else
-# define AESGCM_CIPHER_MODES
-#endif
-
-#ifdef HAVE_EVP_SHA256
-# define KEX_SHA2_METHODS \
+	"ecdh-sha2-nistp521," \
 	"diffie-hellman-group-exchange-sha256," \
 	"diffie-hellman-group16-sha512," \
-	"diffie-hellman-group18-sha512,"
-# define KEX_SHA2_GROUP14 \
-	"diffie-hellman-group14-sha256,"
-#define	SHA2_HMAC_MODES \
-	"hmac-sha2-256," \
-	"hmac-sha2-512,"
-#else
-# define KEX_SHA2_METHODS
-# define KEX_SHA2_GROUP14
-# define SHA2_HMAC_MODES
-#endif
-
-#ifdef WITH_OPENSSL
-# ifdef HAVE_EVP_SHA256
-#  define KEX_CURVE25519_METHODS \
-	"curve25519-sha256," \
-	"curve25519-sha256@libssh.org,"
-# else
-#  define KEX_CURVE25519_METHODS ""
-# endif
-#define KEX_SERVER_KEX \
-	KEX_CURVE25519_METHODS \
-	KEX_ECDH_METHODS \
-	KEX_SHA2_METHODS \
-	KEX_SHA2_GROUP14
+	"diffie-hellman-group18-sha512," \
+	"diffie-hellman-group14-sha256"
 
 #define KEX_CLIENT_KEX KEX_SERVER_KEX
 
 #define	KEX_DEFAULT_PK_ALG	\
-	HOSTKEY_ECDSA_CERT_METHODS \
+	"ecdsa-sha2-nistp256-cert-v01@openssh.com," \
+	"ecdsa-sha2-nistp384-cert-v01@openssh.com," \
+	"ecdsa-sha2-nistp521-cert-v01@openssh.com," \
+	"sk-ecdsa-sha2-nistp256-cert-v01@openssh.com," \
 	"ssh-ed25519-cert-v01@openssh.com," \
 	"sk-ssh-ed25519-cert-v01@openssh.com," \
 	"rsa-sha2-512-cert-v01@openssh.com," \
 	"rsa-sha2-256-cert-v01@openssh.com," \
 	"ssh-rsa-cert-v01@openssh.com," \
-	HOSTKEY_ECDSA_METHODS \
+	"ecdsa-sha2-nistp256," \
+	"ecdsa-sha2-nistp384," \
+	"ecdsa-sha2-nistp521," \
+	"sk-ecdsa-sha2-nistp256@openssh.com," \
 	"ssh-ed25519," \
 	"sk-ssh-ed25519@openssh.com," \
 	"rsa-sha2-512," \
 	"rsa-sha2-256," \
 	"ssh-rsa"
 
-/* the actual algorithms */
-
-#define KEX_SERVER_ENCRYPT \
+#define	KEX_SERVER_ENCRYPT \
 	"chacha20-poly1305@openssh.com," \
-	"aes128-ctr,aes192-ctr,aes256-ctr" \
-	AESGCM_CIPHER_MODES
+	"aes128-ctr,aes192-ctr,aes256-ctr," \
+	"aes128-gcm@openssh.com,aes256-gcm@openssh.com"
 
 #define KEX_CLIENT_ENCRYPT KEX_SERVER_ENCRYPT
 
-#define KEX_SERVER_MAC \
+#define	KEX_SERVER_MAC \
 	"umac-64-etm@openssh.com," \
 	"umac-128-etm@openssh.com," \
 	"hmac-sha2-256-etm@openssh.com," \
@@ -143,44 +80,16 @@
 
 /* Not a KEX value, but here so all the algorithm defaults are together */
 #define	SSH_ALLOWED_CA_SIGALGS	\
-	HOSTKEY_ECDSA_METHODS \
+	"ecdsa-sha2-nistp256," \
+	"ecdsa-sha2-nistp384," \
+	"ecdsa-sha2-nistp521," \
+	"sk-ecdsa-sha2-nistp256@openssh.com," \
 	"ssh-ed25519," \
 	"sk-ssh-ed25519@openssh.com," \
 	"rsa-sha2-512," \
 	"rsa-sha2-256," \
 	"ssh-rsa"
 
-#else /* WITH_OPENSSL */
-
-#define KEX_SERVER_KEX		\
-	"curve25519-sha256," \
-	"curve25519-sha256@libssh.org"
-#define	KEX_DEFAULT_PK_ALG	\
-	"ssh-ed25519-cert-v01@openssh.com," \
-	"ssh-ed25519"
-#define	KEX_SERVER_ENCRYPT \
-	"chacha20-poly1305@openssh.com," \
-	"aes128-ctr,aes192-ctr,aes256-ctr"
-#define	KEX_SERVER_MAC \
-	"umac-64-etm@openssh.com," \
-	"umac-128-etm@openssh.com," \
-	"hmac-sha2-256-etm@openssh.com," \
-	"hmac-sha2-512-etm@openssh.com," \
-	"hmac-sha1-etm@openssh.com," \
-	"umac-64@openssh.com," \
-	"umac-128@openssh.com," \
-	"hmac-sha2-256," \
-	"hmac-sha2-512," \
-	"hmac-sha1"
-
-#define KEX_CLIENT_KEX KEX_SERVER_KEX
-#define	KEX_CLIENT_ENCRYPT KEX_SERVER_ENCRYPT
-#define KEX_CLIENT_MAC KEX_SERVER_MAC
-
-#define	SSH_ALLOWED_CA_SIGALGS	"ssh-ed25519,sk-ssh-ed25519@openssh.com"
-
-#endif /* WITH_OPENSSL */
-
 #define	KEX_DEFAULT_COMP	"none,zlib@openssh.com"
 #define	KEX_DEFAULT_LANG	""
 
@@ -207,4 +116,3 @@
 	KEX_DEFAULT_COMP, \
 	KEX_DEFAULT_LANG, \
 	KEX_DEFAULT_LANG
-
diff --git a/readconf.c b/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
@@ -314,6 +314,16 @@ 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.
@@ -2003,6 +2013,7 @@ 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)
@@ -2167,24 +2178,35 @@ 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 { \
@@ -2634,14 +2656,7 @@ 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);
@@ -2698,20 +2713,20 @@ 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);
 	dump_cfg_string(oHostbasedKeyTypes, o->hostbased_key_types);
 	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

diff --git a/readconf.h b/readconf.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: readconf.h,v 1.131 2019/12/21 02:19:13 djm Exp $ */
+/* $OpenBSD: readconf.h,v 1.132 2020/01/23 02:46:49 dtucker Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -199,6 +199,7 @@ typedef struct {
 #define SSH_STRICT_HOSTKEY_YES	2
 #define SSH_STRICT_HOSTKEY_ASK	3
 
+const char *kex_default_pk_alg(void);
 void     initialize_options(Options *);
 void     fill_default_options(Options *);
 void	 fill_default_options_for_canonicalization(Options *);