upstream commit

adapt kex to sshbuf and struct ssh; ok djm@

1 files changed, 175 insertions, 112 deletions

diff --git a/kexgexc.c b/kexgexc.c
index 18d09cfb0..0898824f3 100644
--- a/kexgexc.c
+++ b/kexgexc.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kexgexc.c,v 1.18 2015/01/19 19:52:16 markus Exp $ */
+/* $OpenBSD: kexgexc.c,v 1.19 2015/01/19 20:16:15 markus Exp $ */
 /*
  * Copyright (c) 2000 Niels Provos.  All rights reserved.
  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
@@ -37,174 +37,237 @@
 #include <string.h>
 #include <signal.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"
 #include "dh.h"
 #include "ssh2.h"
 #include "compat.h"
+#include "dispatch.h"
+#include "ssherr.h"
+#include "sshbuf.h"
 
-void
-kexgex_client(Kex *kex)
+static int input_kex_dh_gex_group(int, u_int32_t, void *);
+static int input_kex_dh_gex_reply(int, u_int32_t, void *);
+
+int
+kexgex_client(struct ssh *ssh)
 {
-        BIGNUM *dh_server_pub = NULL, *shared_secret = NULL;
-        BIGNUM *p = NULL, *g = NULL;
-        Key *server_host_key;
-        u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL;
-        u_int klen, slen, sbloblen, hashlen;
-        int kout;
-        int min, max, nbits;
-        DH *dh;
+        struct kex *kex = ssh->kex;
+        int r;
+        u_int nbits;
 
         nbits = dh_estimate(kex->dh_need * 8);
 
-        if (datafellows & SSH_OLD_DHGEX) {
+        kex->min = DH_GRP_MIN;
+        kex->max = DH_GRP_MAX;
+        kex->nbits = nbits;
+        if (ssh->compat & SSH_OLD_DHGEX) {
                 /* Old GEX request */
-                packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST_OLD);
-                packet_put_int(nbits);
-                min = DH_GRP_MIN;
-                max = DH_GRP_MAX;
-
-                debug("SSH2_MSG_KEX_DH_GEX_REQUEST_OLD(%u) sent", nbits);
+                if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_DH_GEX_REQUEST_OLD))
+                    != 0 ||
+                    (r = sshpkt_put_u32(ssh, kex->nbits)) != 0 ||
+                    (r = sshpkt_send(ssh)) != 0)
+                        goto out;
+                debug("SSH2_MSG_KEX_DH_GEX_REQUEST_OLD(%u) sent", kex->nbits);
         } else {
                 /* New GEX request */
-                min = DH_GRP_MIN;
-                max = DH_GRP_MAX;
-                packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST);
-                packet_put_int(min);
-                packet_put_int(nbits);
-                packet_put_int(max);
-
+                if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_DH_GEX_REQUEST)) != 0 ||
+                    (r = sshpkt_put_u32(ssh, kex->min)) != 0 ||
+                    (r = sshpkt_put_u32(ssh, kex->nbits)) != 0 ||
+                    (r = sshpkt_put_u32(ssh, kex->max)) != 0 ||
+                    (r = sshpkt_send(ssh)) != 0)
+                        goto out;
                 debug("SSH2_MSG_KEX_DH_GEX_REQUEST(%u<%u<%u) sent",
-                    min, nbits, max);
+                    kex->min, kex->nbits, kex->max);
         }
 #ifdef DEBUG_KEXDH
         fprintf(stderr, "\nmin = %d, nbits = %d, max = %d\n",
-            min, nbits, max);
+            kex->min, kex->nbits, kex->max);
 #endif
-        packet_send();
-
-        debug("expecting SSH2_MSG_KEX_DH_GEX_GROUP");
-        packet_read_expect(SSH2_MSG_KEX_DH_GEX_GROUP);
+        ssh_dispatch_set(ssh, SSH2_MSG_KEX_DH_GEX_GROUP,
+            &input_kex_dh_gex_group);
+        r = 0;
+ out:
+        return r;
+}
 
-        if ((p = BN_new()) == NULL)
-                fatal("BN_new");
-        packet_get_bignum2(p);
-        if ((g = BN_new()) == NULL)
-                fatal("BN_new");
-        packet_get_bignum2(g);
-        packet_check_eom();
+static int
+input_kex_dh_gex_group(int type, u_int32_t seq, void *ctxt)
+{
+        struct ssh *ssh = ctxt;
+        struct kex *kex = ssh->kex;
+        BIGNUM *p = NULL, *g = NULL;
+        int r, bits;
 
-        if (BN_num_bits(p) < min || BN_num_bits(p) > max)
-                fatal("DH_GEX group out of range: %d !< %d !< %d",
-                    min, BN_num_bits(p), max);
+        debug("got SSH2_MSG_KEX_DH_GEX_GROUP");
 
-        dh = dh_new_group(g, p);
-        dh_gen_key(dh, kex->we_need * 8);
+        if ((p = BN_new()) == NULL ||
+            (g = BN_new()) == NULL) {
+                r = SSH_ERR_ALLOC_FAIL;
+                goto out;
+        }
+        if ((r = sshpkt_get_bignum2(ssh, p)) != 0 ||
+            (r = sshpkt_get_bignum2(ssh, g)) != 0 ||
+            (r = sshpkt_get_end(ssh)) != 0)
+                goto out;
+        if ((bits = BN_num_bits(p)) < 0 ||
+            (u_int)bits < kex->min || (u_int)bits > kex->max) {
+                r = SSH_ERR_DH_GEX_OUT_OF_RANGE;
+                goto out;
+        }
+        if ((kex->dh = dh_new_group(g, p)) == NULL) {
+                r = SSH_ERR_ALLOC_FAIL;
+                goto out;
+        }
+        p = g = NULL; /* belong to kex->dh now */
 
+        /* generate and send 'e', client DH public key */
+        if ((r = dh_gen_key(kex->dh, kex->we_need * 8)) != 0 ||
+            (r = sshpkt_start(ssh, SSH2_MSG_KEX_DH_GEX_INIT)) != 0 ||
+            (r = sshpkt_put_bignum2(ssh, kex->dh->pub_key)) != 0 ||
+            (r = sshpkt_send(ssh)) != 0)
+                goto out;
+        debug("SSH2_MSG_KEX_DH_GEX_INIT sent");
 #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
+        ssh_dispatch_set(ssh, SSH2_MSG_KEX_DH_GEX_GROUP, NULL);
+        ssh_dispatch_set(ssh, SSH2_MSG_KEX_DH_GEX_REPLY, &input_kex_dh_gex_reply);
+        r = 0;
+out:
+        if (p)
+                BN_clear_free(p);
+        if (g)
+                BN_clear_free(g);
+        return r;
+}
 
-        debug("SSH2_MSG_KEX_DH_GEX_INIT sent");
-        /* generate and send 'e', client DH public key */
-        packet_start(SSH2_MSG_KEX_DH_GEX_INIT);
-        packet_put_bignum2(dh->pub_key);
-        packet_send();
-
-        debug("expecting SSH2_MSG_KEX_DH_GEX_REPLY");
-        packet_read_expect(SSH2_MSG_KEX_DH_GEX_REPLY);
+static int
+input_kex_dh_gex_reply(int type, u_int32_t seq, void *ctxt)
+{
+        struct ssh *ssh = ctxt;
+        struct kex *kex = ssh->kex;
+        BIGNUM *dh_server_pub = NULL, *shared_secret = NULL;
+        struct sshkey *server_host_key = NULL;
+        u_char *kbuf = NULL, *signature = NULL, *server_host_key_blob = NULL;
+        u_char hash[SSH_DIGEST_MAX_LENGTH];
+        size_t klen = 0, slen, sbloblen, hashlen;
+        int kout, r;
 
+        debug("got SSH2_MSG_KEX_DH_GEX_REPLY");
+        if (kex->verify_host_key == NULL) {
+                r = SSH_ERR_INVALID_ARGUMENT;
+                goto out;
+        }
         /* key, cert */
-        server_host_key_blob = packet_get_string(&sbloblen);
-        server_host_key = key_from_blob(server_host_key_blob, sbloblen);
-        if (server_host_key == NULL)
-                fatal("cannot decode server_host_key_blob");
-        if (server_host_key->type != kex->hostkey_type)
-                fatal("type mismatch for decoded server_host_key_blob");
-        if (kex->verify_host_key == NULL)
-                fatal("cannot verify server_host_key");
-        if (kex->verify_host_key(server_host_key) == -1)
-                fatal("server_host_key verification failed");
-
+        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) {
+                r = SSH_ERR_KEY_TYPE_MISMATCH;
+                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 */
-        if ((dh_server_pub = BN_new()) == NULL)
-                fatal("dh_server_pub == NULL");
-        packet_get_bignum2(dh_server_pub);
-
+        if ((dh_server_pub = BN_new()) == NULL) {
+                r = SSH_ERR_ALLOC_FAIL;
+                goto out;
+        }
+        /* signed H */
+        if ((r = sshpkt_get_bignum2(ssh, dh_server_pub)) != 0 ||
+            (r = sshpkt_get_string(ssh, &signature, &slen)) != 0 ||
+            (r = sshpkt_get_end(ssh)) != 0)
+                goto out;
 #ifdef DEBUG_KEXDH
         fprintf(stderr, "dh_server_pub= ");
         BN_print_fp(stderr, dh_server_pub);
         fprintf(stderr, "\n");
         debug("bits %d", BN_num_bits(dh_server_pub));
 #endif
+        if (!dh_pub_is_valid(kex->dh, dh_server_pub)) {
+                sshpkt_disconnect(ssh, "bad server public DH value");
+                r = SSH_ERR_MESSAGE_INCOMPLETE;
+                goto out;
+        }
 
-        /* signed H */
-        signature = packet_get_string(&slen);
-        packet_check_eom();
-
-        if (!dh_pub_is_valid(dh, dh_server_pub))
-                packet_disconnect("bad server public DH value");
-
-        klen = DH_size(dh);
-        kbuf = xmalloc(klen);
-        if ((kout = DH_compute_key(kbuf, dh_server_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_server_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_client: BN_new failed");
-        if (BN_bin2bn(kbuf, kout, shared_secret) == NULL)
-                fatal("kexgex_client: BN_bin2bn failed");
-        explicit_bzero(kbuf, klen);
-        free(kbuf);
-
-        if (datafellows & SSH_OLD_DHGEX)
-                min = max = -1;
+        if (ssh->compat & SSH_OLD_DHGEX)
+                kex->min = kex->max = -1;
 
         /* calc and verify H */
-        kexgex_hash(
+        hashlen = sizeof(hash);
+        if ((r = kexgex_hash(
             kex->hash_alg,
             kex->client_version_string,
             kex->server_version_string,
-            buffer_ptr(kex->my), buffer_len(kex->my),
-            buffer_ptr(kex->peer), buffer_len(kex->peer),
+            sshbuf_ptr(kex->my), sshbuf_len(kex->my),
+            sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
             server_host_key_blob, sbloblen,
-            min, nbits, max,
-            dh->p, dh->g,
-            dh->pub_key,
+            kex->min, kex->nbits, kex->max,
+            kex->dh->p, kex->dh->g,
+            kex->dh->pub_key,
             dh_server_pub,
             shared_secret,
-            &hash, &hashlen
-        );
-
-        /* have keys, free DH */
-        DH_free(dh);
-        free(server_host_key_blob);
-        BN_clear_free(dh_server_pub);
+            hash, &hashlen)) != 0)
+                goto out;
 
-        if (key_verify(server_host_key, signature, slen, hash, hashlen) != 1)
-                fatal("key_verify failed for server_host_key");
-        key_free(server_host_key);
-        free(signature);
+        if ((r = sshkey_verify(server_host_key, signature, slen, hash,
+            hashlen, ssh->compat)) != 0)
+                goto out;
 
         /* save session id */
         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);
         }
-        kex_derive_keys_bn(kex, hash, hashlen, shared_secret);
-        BN_clear_free(shared_secret);
 
-        kex_finish(kex);
+        if ((r = kex_derive_keys_bn(ssh, hash, hashlen, shared_secret)) == 0)
+                r = kex_send_newkeys(ssh);
+ out:
+        explicit_bzero(hash, sizeof(hash));
+        DH_free(kex->dh);
+        kex->dh = NULL;
+        if (dh_server_pub)
+                BN_clear_free(dh_server_pub);
+        if (kbuf) {
+                explicit_bzero(kbuf, klen);
+                free(kbuf);
+        }
+        if (shared_secret)
+                BN_clear_free(shared_secret);
+        sshkey_free(server_host_key);
+        free(server_host_key_blob);
+        free(signature);
+        return r;
 }
 #endif /* WITH_OPENSSL */