upstream commit

adapt kex to sshbuf and struct ssh; ok djm@

1 files changed, 161 insertions, 96 deletions

diff --git a/kexgexs.c b/kexgexs.c
index 1021e0bf6..6e2b009b5 100644
--- a/kexgexs.c
+++ b/kexgexs.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kexgexs.c,v 1.20 2015/01/19 19:52:16 markus Exp $ */
+/* $OpenBSD: kexgexs.c,v 1.21 2015/01/19 20:16:15 markus Exp $ */
 /*
  * Copyright (c) 2000 Niels Provos.  All rights reserved.
  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
@@ -37,10 +37,9 @@
 
 #include <openssl/dh.h>
 
-#include "xmalloc.h"
-#include "buffer.h"
-#include "key.h"
+#include "sshkey.h"
 #include "cipher.h"
+#include "digest.h"
 #include "kex.h"
 #include "log.h"
 #include "packet.h"
@@ -51,33 +50,43 @@
 #include "ssh-gss.h"
 #endif
 #include "monitor_wrap.h"
+#include "dispatch.h"
+#include "ssherr.h"
+#include "sshbuf.h"
 
-void
-kexgex_server(Kex *kex)
+static int input_kex_dh_gex_request(int, u_int32_t, void *);
+static int input_kex_dh_gex_init(int, u_int32_t, void *);
+
+int
+kexgex_server(struct ssh *ssh)
 {
-        BIGNUM *shared_secret = NULL, *dh_client_pub = NULL;
-        Key *server_host_public, *server_host_private;
-        DH *dh;
-        u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL;
-        u_int sbloblen, klen, slen, hashlen;
-        int omin = -1, min = -1, omax = -1, max = -1, onbits = -1, nbits = -1;
-        int type, kout;
+        ssh_dispatch_set(ssh, SSH2_MSG_KEX_DH_GEX_REQUEST_OLD,
+            &input_kex_dh_gex_request);
+        ssh_dispatch_set(ssh, SSH2_MSG_KEX_DH_GEX_REQUEST,
+            &input_kex_dh_gex_request);
+        debug("expecting SSH2_MSG_KEX_DH_GEX_REQUEST");
+        return 0;
+}
+
+static int
+input_kex_dh_gex_request(int type, u_int32_t seq, void *ctxt)
+{
+        struct ssh *ssh = ctxt;
+        struct kex *kex = ssh->kex;
+        int r;
+        u_int min = 0, max = 0, nbits = 0;
 
-        if (kex->load_host_public_key == NULL ||
-            kex->load_host_private_key == NULL)
-                fatal("Cannot load hostkey");
-        server_host_public = kex->load_host_public_key(kex->hostkey_type);
-        if (server_host_public == NULL)
-                fatal("Unsupported hostkey type %d", kex->hostkey_type);
-        server_host_private = kex->load_host_private_key(kex->hostkey_type);
-
-        type = packet_read();
         switch (type) {
         case SSH2_MSG_KEX_DH_GEX_REQUEST:
                 debug("SSH2_MSG_KEX_DH_GEX_REQUEST received");
-                omin = min = packet_get_int();
-                onbits = nbits = packet_get_int();
-                omax = max = packet_get_int();
+                if ((r = sshpkt_get_u32(ssh, &min)) != 0 ||
+                    (r = sshpkt_get_u32(ssh, &nbits)) != 0 ||
+                    (r = sshpkt_get_u32(ssh, &max)) != 0 ||
+                    (r = sshpkt_get_end(ssh)) != 0)
+                        goto out;
+                kex->nbits = nbits;
+                kex->min = min;
+                kex->max = max;
                 min = MAX(DH_GRP_MIN, min);
                 max = MIN(DH_GRP_MAX, max);
                 nbits = MAX(DH_GRP_MIN, nbits);
@@ -85,45 +94,88 @@ kexgex_server(Kex *kex)
                 break;
         case SSH2_MSG_KEX_DH_GEX_REQUEST_OLD:
                 debug("SSH2_MSG_KEX_DH_GEX_REQUEST_OLD received");
-                onbits = nbits = packet_get_int();
+                if ((r = sshpkt_get_u32(ssh, &nbits)) != 0 ||
+                    (r = sshpkt_get_end(ssh)) != 0)
+                        goto out;
+                kex->nbits = nbits;
                 /* unused for old GEX */
-                omin = min = DH_GRP_MIN;
-                omax = max = DH_GRP_MAX;
+                kex->min = min = DH_GRP_MIN;
+                kex->max = max = DH_GRP_MAX;
                 break;
         default:
-                fatal("protocol error during kex, no DH_GEX_REQUEST: %d", type);
+                r = SSH_ERR_INVALID_ARGUMENT;
+                goto out;
         }
-        packet_check_eom();
 
-        if (omax < omin || onbits < omin || omax < onbits)
-                fatal("DH_GEX_REQUEST, bad parameters: %d !< %d !< %d",
-                    omin, onbits, omax);
+        if (kex->max < kex->min || kex->nbits < kex->min ||
+            kex->max < kex->nbits) {
+                r = SSH_ERR_DH_GEX_OUT_OF_RANGE;
+                goto out;
+        }
 
         /* Contact privileged parent */
-        dh = PRIVSEP(choose_dh(min, nbits, max));
-        if (dh == NULL)
-                packet_disconnect("Protocol error: no matching DH grp found");
-
+        kex->dh = PRIVSEP(choose_dh(min, nbits, max));
+        if (kex->dh == NULL) {
+                sshpkt_disconnect(ssh, "no matching DH grp found");
+                r = SSH_ERR_ALLOC_FAIL;
+                goto out;
+        }
         debug("SSH2_MSG_KEX_DH_GEX_GROUP sent");
-        packet_start(SSH2_MSG_KEX_DH_GEX_GROUP);
-        packet_put_bignum2(dh->p);
-        packet_put_bignum2(dh->g);
-        packet_send();
-
-        /* flush */
-        packet_write_wait();
+        if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_DH_GEX_GROUP)) != 0 ||
+            (r = sshpkt_put_bignum2(ssh, kex->dh->p)) != 0 ||
+            (r = sshpkt_put_bignum2(ssh, kex->dh->g)) != 0 ||
+            (r = sshpkt_send(ssh)) != 0)
+                goto out;
 
         /* Compute our exchange value in parallel with the client */
-        dh_gen_key(dh, kex->we_need * 8);
+        if ((r = dh_gen_key(kex->dh, kex->we_need * 8)) != 0)
+                goto out;
+
+        /* old KEX does not use min/max in kexgex_hash() */
+        if (type == SSH2_MSG_KEX_DH_GEX_REQUEST_OLD)
+                kex->min = kex->max = -1;
 
         debug("expecting SSH2_MSG_KEX_DH_GEX_INIT");
-        packet_read_expect(SSH2_MSG_KEX_DH_GEX_INIT);
+        ssh_dispatch_set(ssh, SSH2_MSG_KEX_DH_GEX_INIT, &input_kex_dh_gex_init);
+        r = 0;
+ out:
+        return r;
+}
+
+static int
+input_kex_dh_gex_init(int type, u_int32_t seq, void *ctxt)
+{
+        struct ssh *ssh = ctxt;
+        struct kex *kex = ssh->kex;
+        BIGNUM *shared_secret = NULL, *dh_client_pub = NULL;
+        struct sshkey *server_host_public, *server_host_private;
+        u_char *kbuf = NULL, *signature = NULL, *server_host_key_blob = NULL;
+        u_char hash[SSH_DIGEST_MAX_LENGTH];
+        size_t sbloblen, slen;
+        size_t klen = 0, hashlen;
+        int kout, r;
+
+        if (kex->load_host_public_key == NULL ||
+            kex->load_host_private_key == NULL) {
+                r = SSH_ERR_INVALID_ARGUMENT;
+                goto out;
+        }
+        if ((server_host_public = kex->load_host_public_key(kex->hostkey_type,
+            ssh)) == NULL ||
+            (server_host_private = kex->load_host_private_key(kex->hostkey_type,
+            ssh)) == NULL) {
+                r = SSH_ERR_NO_HOSTKEY_LOADED;
+                goto out;
+        }
 
         /* key, cert */
-        if ((dh_client_pub = BN_new()) == NULL)
-                fatal("dh_client_pub == NULL");
-        packet_get_bignum2(dh_client_pub);
-        packet_check_eom();
+        if ((dh_client_pub = BN_new()) == NULL) {
+                r = SSH_ERR_ALLOC_FAIL;
+                goto out;
+        }
+        if ((r = sshpkt_get_bignum2(ssh, dh_client_pub)) != 0 ||
+            (r = sshpkt_get_end(ssh)) != 0)
+                goto out;
 
 #ifdef DEBUG_KEXDH
         fprintf(stderr, "dh_client_pub= ");
@@ -133,79 +185,92 @@ kexgex_server(Kex *kex)
 #endif
 
 #ifdef DEBUG_KEXDH
-        DHparams_print_fp(stderr, dh);
+        DHparams_print_fp(stderr, kex->dh);
         fprintf(stderr, "pub= ");
-        BN_print_fp(stderr, dh->pub_key);
+        BN_print_fp(stderr, kex->dh->pub_key);
         fprintf(stderr, "\n");
 #endif
-        if (!dh_pub_is_valid(dh, dh_client_pub))
-                packet_disconnect("bad client public DH value");
+        if (!dh_pub_is_valid(kex->dh, dh_client_pub)) {
+                sshpkt_disconnect(ssh, "bad client public DH value");
+                r = SSH_ERR_MESSAGE_INCOMPLETE;
+                goto out;
+        }
 
-        klen = DH_size(dh);
-        kbuf = xmalloc(klen);
-        if ((kout = DH_compute_key(kbuf, dh_client_pub, dh)) < 0)
-                fatal("DH_compute_key: failed");
+        klen = DH_size(kex->dh);
+        if ((kbuf = malloc(klen)) == NULL ||
+            (shared_secret = BN_new()) == NULL) {
+                r = SSH_ERR_ALLOC_FAIL;
+                goto out;
+        }
+        if ((kout = DH_compute_key(kbuf, dh_client_pub, kex->dh)) < 0 ||
+            BN_bin2bn(kbuf, kout, shared_secret) == NULL) {
+                r = SSH_ERR_LIBCRYPTO_ERROR;
+                goto out;
+        }
 #ifdef DEBUG_KEXDH
         dump_digest("shared secret", kbuf, kout);
 #endif
-        if ((shared_secret = BN_new()) == NULL)
-                fatal("kexgex_server: BN_new failed");
-        if (BN_bin2bn(kbuf, kout, shared_secret) == NULL)
-                fatal("kexgex_server: BN_bin2bn failed");
-        explicit_bzero(kbuf, klen);
-        free(kbuf);
-
-        key_to_blob(server_host_public, &server_host_key_blob, &sbloblen);
-
-        if (type == SSH2_MSG_KEX_DH_GEX_REQUEST_OLD)
-                omin = min = omax = max = -1;
-
+        if ((r = sshkey_to_blob(server_host_public, &server_host_key_blob,
+            &sbloblen)) != 0)
+                goto out;
         /* calc H */
-        kexgex_hash(
+        hashlen = sizeof(hash);
+        if ((r = kexgex_hash(
             kex->hash_alg,
             kex->client_version_string,
             kex->server_version_string,
-            buffer_ptr(kex->peer), buffer_len(kex->peer),
-            buffer_ptr(kex->my), buffer_len(kex->my),
+            sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
+            sshbuf_ptr(kex->my), sshbuf_len(kex->my),
             server_host_key_blob, sbloblen,
-            omin, onbits, omax,
-            dh->p, dh->g,
+            kex->min, kex->nbits, kex->max,
+            kex->dh->p, kex->dh->g,
             dh_client_pub,
-            dh->pub_key,
+            kex->dh->pub_key,
             shared_secret,
-            &hash, &hashlen
-        );
-        BN_clear_free(dh_client_pub);
+            hash, &hashlen)) != 0)
+                goto out;
 
         /* save session id := H */
         if (kex->session_id == NULL) {
                 kex->session_id_len = hashlen;
-                kex->session_id = xmalloc(kex->session_id_len);
+                kex->session_id = malloc(kex->session_id_len);
+                if (kex->session_id == NULL) {
+                        r = SSH_ERR_ALLOC_FAIL;
+                        goto out;
+                }
                 memcpy(kex->session_id, hash, kex->session_id_len);
         }
 
         /* sign H */
-        kex->sign(server_host_private, server_host_public, &signature, &slen,
-            hash, hashlen);
+        if ((r = kex->sign(server_host_private, server_host_public,
+            &signature, &slen, hash, hashlen, ssh->compat)) < 0)
+                goto out;
 
         /* destroy_sensitive_data(); */
 
         /* send server hostkey, DH pubkey 'f' and singed H */
-        debug("SSH2_MSG_KEX_DH_GEX_REPLY sent");
-        packet_start(SSH2_MSG_KEX_DH_GEX_REPLY);
-        packet_put_string(server_host_key_blob, sbloblen);
-        packet_put_bignum2(dh->pub_key);        /* f */
-        packet_put_string(signature, slen);
-        packet_send();
+        if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_DH_GEX_REPLY)) != 0 ||
+            (r = sshpkt_put_string(ssh, server_host_key_blob, sbloblen)) != 0 ||
+            (r = sshpkt_put_bignum2(ssh, kex->dh->pub_key)) != 0 ||     /* f */
+            (r = sshpkt_put_string(ssh, signature, slen)) != 0 ||
+            (r = sshpkt_send(ssh)) != 0)
+                goto out;
 
-        free(signature);
+        if ((r = kex_derive_keys_bn(ssh, hash, hashlen, shared_secret)) == 0)
+                r = kex_send_newkeys(ssh);
+ out:
+        DH_free(kex->dh);
+        kex->dh = NULL;
+        if (dh_client_pub)
+                BN_clear_free(dh_client_pub);
+        if (kbuf) {
+                explicit_bzero(kbuf, klen);
+                free(kbuf);
+        }
+        if (shared_secret)
+                BN_clear_free(shared_secret);
         free(server_host_key_blob);
-        /* have keys, free DH */
-        DH_free(dh);
-
-        kex_derive_keys_bn(kex, hash, hashlen, shared_secret);
-        BN_clear_free(shared_secret);
-
-        kex_finish(kex);
+        free(signature);
+        return r;
 }
 #endif /* WITH_OPENSSL */