upstream: forgot to cvs add this file in previous series of commits;

grrr

OpenBSD-Commit-ID: bcff316c3e7da8fd15333e05d244442c3aaa66b0

1 files changed, 322 insertions, 0 deletions

diff --git a/kexgen.c b/kexgen.c
new file mode 100644
index 00000000..3983c9f6
--- /dev/null
+++ b/kexgen.c
@@ -0,0 +1,322 @@
+/* $OpenBSD: kexgen.c,v 1.1 2019/01/21 11:22:00 djm Exp $ */
+/*
+ * Copyright (c) 2019 Markus Friedl.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/types.h>
+
+#include <stdio.h>
+#include <string.h>
+#include <signal.h>
+
+#include "sshkey.h"
+#include "kex.h"
+#include "log.h"
+#include "packet.h"
+#include "ssh2.h"
+#include "sshbuf.h"
+#include "digest.h"
+#include "ssherr.h"
+
+static int input_kex_gen_init(int, u_int32_t, struct ssh *);
+static int input_kex_gen_reply(int type, u_int32_t seq, struct ssh *ssh);
+
+static int
+kex_gen_hash(
+    int hash_alg,
+    const struct sshbuf *client_version,
+    const struct sshbuf *server_version,
+    const u_char *ckexinit, size_t ckexinitlen,
+    const u_char *skexinit, size_t skexinitlen,
+    const u_char *serverhostkeyblob, size_t sbloblen,
+    const struct sshbuf *client_pub,
+    const struct sshbuf *server_pub,
+    const struct sshbuf *shared_secret,
+    u_char *hash, size_t *hashlen)
+{
+	struct sshbuf *b;
+	int r;
+
+	if (*hashlen < ssh_digest_bytes(hash_alg))
+		return SSH_ERR_INVALID_ARGUMENT;
+	if ((b = sshbuf_new()) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+	if ((r = sshbuf_put_stringb(b, client_version)) != 0 ||
+	    (r = sshbuf_put_stringb(b, server_version)) != 0 ||
+	    /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
+	    (r = sshbuf_put_u32(b, ckexinitlen+1)) != 0 ||
+	    (r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) != 0 ||
+	    (r = sshbuf_put(b, ckexinit, ckexinitlen)) != 0 ||
+	    (r = sshbuf_put_u32(b, skexinitlen+1)) != 0 ||
+	    (r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) != 0 ||
+	    (r = sshbuf_put(b, skexinit, skexinitlen)) != 0 ||
+	    (r = sshbuf_put_string(b, serverhostkeyblob, sbloblen)) != 0 ||
+	    (r = sshbuf_put_stringb(b, client_pub)) != 0 ||
+	    (r = sshbuf_put_stringb(b, server_pub)) != 0 ||
+	    (r = sshbuf_putb(b, shared_secret)) != 0) {
+		sshbuf_free(b);
+		return r;
+	}
+#ifdef DEBUG_KEX
+	sshbuf_dump(b, stderr);
+#endif
+	if (ssh_digest_buffer(hash_alg, b, hash, *hashlen) != 0) {
+		sshbuf_free(b);
+		return SSH_ERR_LIBCRYPTO_ERROR;
+	}
+	sshbuf_free(b);
+	*hashlen = ssh_digest_bytes(hash_alg);
+#ifdef DEBUG_KEX
+	dump_digest("hash", hash, *hashlen);
+#endif
+	return 0;
+}
+
+int
+kex_gen_client(struct ssh *ssh)
+{
+	struct kex *kex = ssh->kex;
+	int r;
+
+	switch (kex->kex_type) {
+	case KEX_DH_GRP1_SHA1:
+	case KEX_DH_GRP14_SHA1:
+	case KEX_DH_GRP14_SHA256:
+	case KEX_DH_GRP16_SHA512:
+	case KEX_DH_GRP18_SHA512:
+		r = kex_dh_keypair(kex);
+		break;
+	case KEX_ECDH_SHA2:
+		r = kex_ecdh_keypair(kex);
+		break;
+	case KEX_C25519_SHA256:
+		r = kex_c25519_keypair(kex);
+		break;
+	case KEX_KEM_SNTRUP4591761X25519_SHA512:
+		r = kex_kem_sntrup4591761x25519_keypair(kex);
+		break;
+	default:
+		r = SSH_ERR_INVALID_ARGUMENT;
+		break;
+	}
+	if (r != 0)
+		return r;
+	if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_ECDH_INIT)) != 0 ||
+	    (r = sshpkt_put_stringb(ssh, kex->client_pub)) != 0 ||
+	    (r = sshpkt_send(ssh)) != 0)
+		return r;
+	debug("expecting SSH2_MSG_KEX_ECDH_REPLY");
+	ssh_dispatch_set(ssh, SSH2_MSG_KEX_ECDH_REPLY, &input_kex_gen_reply);
+	return 0;
+}
+
+static int
+input_kex_gen_reply(int type, u_int32_t seq, struct ssh *ssh)
+{
+	struct kex *kex = ssh->kex;
+	struct sshkey *server_host_key = NULL;
+	struct sshbuf *shared_secret = NULL;
+	struct sshbuf *server_blob = NULL;
+	u_char *server_host_key_blob = NULL, *signature = NULL;
+	u_char hash[SSH_DIGEST_MAX_LENGTH];
+	size_t slen, sbloblen, hashlen;
+	int r;
+
+	/* hostkey */
+	if ((r = sshpkt_get_string(ssh, &server_host_key_blob,
+	    &sbloblen)) != 0 ||
+	    (r = sshkey_from_blob(server_host_key_blob, sbloblen,
+	    &server_host_key)) != 0)
+		goto out;
+	if ((r = kex_verify_host_key(ssh, server_host_key)) != 0)
+		goto out;
+
+	/* Q_S, server public key */
+	/* signed H */
+	if ((r = sshpkt_getb_froms(ssh, &server_blob)) != 0 ||
+	    (r = sshpkt_get_string(ssh, &signature, &slen)) != 0 ||
+	    (r = sshpkt_get_end(ssh)) != 0)
+		goto out;
+
+	/* compute shared secret */
+	switch (kex->kex_type) {
+	case KEX_DH_GRP1_SHA1:
+	case KEX_DH_GRP14_SHA1:
+	case KEX_DH_GRP14_SHA256:
+	case KEX_DH_GRP16_SHA512:
+	case KEX_DH_GRP18_SHA512:
+		r = kex_dh_dec(kex, server_blob, &shared_secret);
+		break;
+	case KEX_ECDH_SHA2:
+		r = kex_ecdh_dec(kex, server_blob, &shared_secret);
+		break;
+	case KEX_C25519_SHA256:
+		r = kex_c25519_dec(kex, server_blob, &shared_secret);
+		break;
+	case KEX_KEM_SNTRUP4591761X25519_SHA512:
+		r = kex_kem_sntrup4591761x25519_dec(kex, server_blob,
+		    &shared_secret);
+		break;
+	default:
+		r = SSH_ERR_INVALID_ARGUMENT;
+		break;
+	}
+	if (r !=0 )
+		goto out;
+
+	/* calc and verify H */
+	hashlen = sizeof(hash);
+	if ((r = kex_gen_hash(
+	    kex->hash_alg,
+	    kex->client_version,
+	    kex->server_version,
+	    sshbuf_ptr(kex->my), sshbuf_len(kex->my),
+	    sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
+	    server_host_key_blob, sbloblen,
+	    kex->client_pub,
+	    server_blob,
+	    shared_secret,
+	    hash, &hashlen)) != 0)
+		goto out;
+
+	if ((r = sshkey_verify(server_host_key, signature, slen, hash, hashlen,
+	    kex->hostkey_alg, ssh->compat)) != 0)
+		goto out;
+
+	if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0)
+		r = kex_send_newkeys(ssh);
+out:
+	explicit_bzero(hash, sizeof(hash));
+	explicit_bzero(kex->c25519_client_key, sizeof(kex->c25519_client_key));
+	explicit_bzero(kex->sntrup4591761_client_key,
+	    sizeof(kex->sntrup4591761_client_key));
+	free(server_host_key_blob);
+	free(signature);
+	sshkey_free(server_host_key);
+	sshbuf_free(server_blob);
+	sshbuf_free(shared_secret);
+	sshbuf_free(kex->client_pub);
+	kex->client_pub = NULL;
+	return r;
+}
+
+int
+kex_gen_server(struct ssh *ssh)
+{
+	debug("expecting SSH2_MSG_KEX_ECDH_INIT");
+	ssh_dispatch_set(ssh, SSH2_MSG_KEX_ECDH_INIT, &input_kex_gen_init);
+	return 0;
+}
+
+static int
+input_kex_gen_init(int type, u_int32_t seq, struct ssh *ssh)
+{
+	struct kex *kex = ssh->kex;
+	struct sshkey *server_host_private, *server_host_public;
+	struct sshbuf *shared_secret = NULL;
+	struct sshbuf *server_pubkey = NULL;
+	struct sshbuf *client_pubkey = NULL;
+	u_char *server_host_key_blob = NULL, *signature = NULL;
+	u_char hash[SSH_DIGEST_MAX_LENGTH];
+	size_t slen, sbloblen, hashlen;
+	int r;
+
+	if ((r = kex_load_hostkey(ssh, &server_host_private,
+	    &server_host_public)) != 0)
+		goto out;
+
+	if ((r = sshpkt_getb_froms(ssh, &client_pubkey)) != 0 ||
+	    (r = sshpkt_get_end(ssh)) != 0)
+		goto out;
+
+	/* compute shared secret */
+	switch (kex->kex_type) {
+	case KEX_DH_GRP1_SHA1:
+	case KEX_DH_GRP14_SHA1:
+	case KEX_DH_GRP14_SHA256:
+	case KEX_DH_GRP16_SHA512:
+	case KEX_DH_GRP18_SHA512:
+		r = kex_dh_enc(kex, client_pubkey, &server_pubkey,
+		    &shared_secret);
+		break;
+	case KEX_ECDH_SHA2:
+		r = kex_ecdh_enc(kex, client_pubkey, &server_pubkey,
+		    &shared_secret);
+		break;
+	case KEX_C25519_SHA256:
+		r = kex_c25519_enc(kex, client_pubkey, &server_pubkey,
+		    &shared_secret);
+		break;
+	case KEX_KEM_SNTRUP4591761X25519_SHA512:
+		r = kex_kem_sntrup4591761x25519_enc(kex, client_pubkey,
+		    &server_pubkey, &shared_secret);
+		break;
+	default:
+		r = SSH_ERR_INVALID_ARGUMENT;
+		break;
+	}
+	if (r !=0 )
+		goto out;
+
+	/* calc H */
+	if ((r = sshkey_to_blob(server_host_public, &server_host_key_blob,
+	    &sbloblen)) != 0)
+		goto out;
+	hashlen = sizeof(hash);
+	if ((r = kex_gen_hash(
+	    kex->hash_alg,
+	    kex->client_version,
+	    kex->server_version,
+	    sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
+	    sshbuf_ptr(kex->my), sshbuf_len(kex->my),
+	    server_host_key_blob, sbloblen,
+	    client_pubkey,
+	    server_pubkey,
+	    shared_secret,
+	    hash, &hashlen)) != 0)
+		goto out;
+
+	/* sign H */
+	if ((r = kex->sign(ssh, server_host_private, server_host_public,
+	     &signature, &slen, hash, hashlen, kex->hostkey_alg)) != 0)
+		goto out;
+
+	/* send server hostkey, ECDH pubkey 'Q_S' and signed H */
+	if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_ECDH_REPLY)) != 0 ||
+	    (r = sshpkt_put_string(ssh, server_host_key_blob, sbloblen)) != 0 ||
+	    (r = sshpkt_put_stringb(ssh, server_pubkey)) != 0 ||
+	    (r = sshpkt_put_string(ssh, signature, slen)) != 0 ||
+	    (r = sshpkt_send(ssh)) != 0)
+		goto out;
+
+	if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0)
+		r = kex_send_newkeys(ssh);
+out:
+	explicit_bzero(hash, sizeof(hash));
+	free(server_host_key_blob);
+	free(signature);
+	sshbuf_free(shared_secret);
+	sshbuf_free(client_pubkey);
+	sshbuf_free(server_pubkey);
+	return r;
+}