upstream: factor out kex_verify_hostkey() - again, duplicated

almost exactly across client and server for several KEX methods.

from markus@ ok djm@

OpenBSD-Commit-ID: 4e4a16d949dadde002a0aacf6d280a684e20829c

6 files changed, 27 insertions, 59 deletions

diff --git a/kex.c b/kex.c
index a0d13a880..d8c71bb3e 100644
--- a/kex.c
+++ b/kex.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kex.c,v 1.145 2019/01/21 10:05:09 djm Exp $ */
+/* $OpenBSD: kex.c,v 1.146 2019/01/21 10:07:22 djm Exp $ */
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  *
@@ -1071,6 +1071,22 @@ kex_load_hostkey(struct ssh *ssh, struct sshkey **pubp, struct sshkey **prvp)
         return 0;
 }
 
+int
+kex_verify_host_key(struct ssh *ssh, struct sshkey *server_host_key)
+{
+        struct kex *kex = ssh->kex;
+
+        if (kex->verify_host_key == NULL)
+                return SSH_ERR_INVALID_ARGUMENT;
+        if (server_host_key->type != kex->hostkey_type ||
+            (kex->hostkey_type == KEY_ECDSA &&
+            server_host_key->ecdsa_nid != kex->hostkey_nid))
+                return SSH_ERR_KEY_TYPE_MISMATCH;
+        if (kex->verify_host_key(server_host_key, ssh) == -1)
+                return  SSH_ERR_SIGNATURE_INVALID;
+        return 0;
+}
+
 #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH)
 void
 dump_digest(char *msg, u_char *digest, int len)
diff --git a/kex.h b/kex.h
index fa65b8657..e404d0365 100644
--- a/kex.h
+++ b/kex.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: kex.h,v 1.97 2019/01/21 10:05:09 djm Exp $ */
+/* $OpenBSD: kex.h,v 1.98 2019/01/21 10:07:22 djm Exp $ */
 
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
@@ -185,6 +185,7 @@ int	 kex_buf2prop(struct sshbuf *, int *, char ***);
 int      kex_prop2buf(struct sshbuf *, char *proposal[PROPOSAL_MAX]);
 void     kex_prop_free(char **);
 int      kex_load_hostkey(struct ssh *, struct sshkey **, struct sshkey **);
+int      kex_verify_host_key(struct ssh *, struct sshkey *);
 
 int      kex_send_kexinit(struct ssh *);
 int      kex_input_kexinit(int, u_int32_t, struct ssh *);
diff --git a/kexc25519c.c b/kexc25519c.c
index 59b4e4cc0..1c7f79000 100644
--- a/kexc25519c.c
+++ b/kexc25519c.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kexc25519c.c,v 1.11 2019/01/21 09:55:52 djm Exp $ */
+/* $OpenBSD: kexc25519c.c,v 1.12 2019/01/21 10:07:22 djm Exp $ */
 /*
  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
  * Copyright (c) 2010 Damien Miller.  All rights reserved.
@@ -80,27 +80,14 @@ input_kex_c25519_reply(int type, u_int32_t seq, struct ssh *ssh)
         size_t slen, pklen, sbloblen, hashlen;
         int r;
 
-        if (kex->verify_host_key == NULL) {
-                r = SSH_ERR_INVALID_ARGUMENT;
-                goto out;
-        }
-
         /* 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 (server_host_key->type != kex->hostkey_type ||
-            (kex->hostkey_type == KEY_ECDSA &&
-            server_host_key->ecdsa_nid != kex->hostkey_nid)) {
-                r = SSH_ERR_KEY_TYPE_MISMATCH;
+        if ((r = kex_verify_host_key(ssh, server_host_key)) != 0)
                 goto out;
-        }
-        if (kex->verify_host_key(server_host_key, ssh) == -1) {
-                r = SSH_ERR_SIGNATURE_INVALID;
-                goto out;
-        }
 
         /* Q_S, server public key */
         /* signed H */
diff --git a/kexdhc.c b/kexdhc.c
index 2e26f22ea..a2af8cb08 100644
--- a/kexdhc.c
+++ b/kexdhc.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kexdhc.c,v 1.28 2019/01/21 10:03:37 djm Exp $ */
+/* $OpenBSD: kexdhc.c,v 1.29 2019/01/21 10:07:22 djm Exp $ */
 /*
  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
  *
@@ -95,26 +95,14 @@ input_kex_dh(int type, u_int32_t seq, struct ssh *ssh)
         size_t slen, sbloblen, hashlen;
         int r;
 
-        if (kex->verify_host_key == NULL) {
-                r = SSH_ERR_INVALID_ARGUMENT;
-                goto out;
-        }
         /* key, cert */
         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 (server_host_key->type != kex->hostkey_type ||
-            (kex->hostkey_type == KEY_ECDSA &&
-            server_host_key->ecdsa_nid != kex->hostkey_nid)) {
-                r = SSH_ERR_KEY_TYPE_MISMATCH;
+        if ((r = kex_verify_host_key(ssh, server_host_key)) != 0)
                 goto out;
-        }
-        if (kex->verify_host_key(server_host_key, ssh) == -1) {
-                r = SSH_ERR_SIGNATURE_INVALID;
-                goto out;
-        }
         /* DH parameter f, server public DH key, signed H */
         if ((r = sshpkt_get_bignum2(ssh, &dh_server_pub)) != 0 ||
             (r = sshpkt_get_string(ssh, &signature, &slen)) != 0 ||
diff --git a/kexecdhc.c b/kexecdhc.c
index 2cff34347..bfb9f4707 100644
--- a/kexecdhc.c
+++ b/kexecdhc.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kexecdhc.c,v 1.15 2019/01/21 09:55:52 djm Exp $ */
+/* $OpenBSD: kexecdhc.c,v 1.16 2019/01/21 10:07:22 djm Exp $ */
 /*
  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
  * Copyright (c) 2010 Damien Miller.  All rights reserved.
@@ -109,10 +109,6 @@ input_kex_ecdh_reply(int type, u_int32_t seq, struct ssh *ssh)
         size_t klen = 0, hashlen;
         int r;
 
-        if (kex->verify_host_key == NULL) {
-                r = SSH_ERR_INVALID_ARGUMENT;
-                goto out;
-        }
         group = kex->ec_group;
         client_key = kex->ec_client_key;
 
@@ -122,16 +118,8 @@ input_kex_ecdh_reply(int type, u_int32_t seq, struct ssh *ssh)
             (r = sshkey_from_blob(server_host_key_blob, sbloblen,
             &server_host_key)) != 0)
                 goto out;
-        if (server_host_key->type != kex->hostkey_type ||
-            (kex->hostkey_type == KEY_ECDSA &&
-            server_host_key->ecdsa_nid != kex->hostkey_nid)) {
-                r = SSH_ERR_KEY_TYPE_MISMATCH;
+        if ((r = kex_verify_host_key(ssh, server_host_key)) != 0)
                 goto out;
-        }
-        if (kex->verify_host_key(server_host_key, ssh) == -1) {
-                r = SSH_ERR_SIGNATURE_INVALID;
-                goto out;
-        }
 
         /* Q_S, server public key */
         /* signed H */
diff --git a/kexgexc.c b/kexgexc.c
index 600d91acc..ac42127af 100644
--- a/kexgexc.c
+++ b/kexgexc.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kexgexc.c,v 1.32 2019/01/21 10:03:37 djm Exp $ */
+/* $OpenBSD: kexgexc.c,v 1.33 2019/01/21 10:07:22 djm Exp $ */
 /*
  * Copyright (c) 2000 Niels Provos.  All rights reserved.
  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
@@ -153,26 +153,14 @@ input_kex_dh_gex_reply(int type, u_int32_t seq, struct ssh *ssh)
         int r;
 
         debug("got SSH2_MSG_KEX_DH_GEX_REPLY");
-        if (kex->verify_host_key == NULL) {
-                r = SSH_ERR_INVALID_ARGUMENT;
-                goto out;
-        }
         /* key, cert */
         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 (server_host_key->type != kex->hostkey_type ||
-            (kex->hostkey_type == KEY_ECDSA &&
-            server_host_key->ecdsa_nid != kex->hostkey_nid)) {
-                r = SSH_ERR_KEY_TYPE_MISMATCH;
+        if ((r = kex_verify_host_key(ssh, server_host_key)) != 0)
                 goto out;
-        }
-        if (kex->verify_host_key(server_host_key, ssh) == -1) {
-                r = SSH_ERR_SIGNATURE_INVALID;
-                goto out;
-        }
         /* DH parameter f, server public DH key, signed H */
         if ((r = sshpkt_get_bignum2(ssh, &dh_server_pub)) != 0 ||
             (r = sshpkt_get_string(ssh, &signature, &slen)) != 0 ||