- OpenBSD CVS update:

   - [packet.h packet.c]
     ssh2 packet format
   - [packet.h packet.c nchan2.ms nchan.h compat.h compat.c]
     [channels.h channels.c]
     channel layer support for ssh2
   - [kex.h kex.c hmac.h hmac.c dsa.c dsa.h]
     DSA, keyexchange, algorithm agreement for ssh2

1 files changed, 407 insertions, 0 deletions

diff --git a/kex.c b/kex.c
new file mode 100644
index 000000000..e730536ac
--- /dev/null
+++ b/kex.c
@@ -0,0 +1,407 @@
+/*
+ * Copyright (c) 2000 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.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *      This product includes software developed by Markus Friedl.
+ * 4. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * 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 "includes.h"
+RCSID("$Id: kex.c,v 1.1 2000/04/04 04:39:02 damien Exp $");
+
+#include "ssh.h"
+#include "ssh2.h"
+#include "xmalloc.h"
+#include "buffer.h"
+#include "bufaux.h"
+#include "cipher.h"
+#include "compat.h"
+
+#if HAVE_OPENSSL
+# include <openssl/bn.h>
+# include <openssl/dh.h>
+# include <openssl/crypto.h>
+# include <openssl/bio.h>
+# include <openssl/bn.h>
+# include <openssl/dh.h>
+# include <openssl/pem.h>
+#endif /* HAVE_OPENSSL */
+#if HAVE_SSL
+# include <ssl/bn.h>
+# include <ssl/dh.h>
+# include <ssl/crypto.h>
+# include <ssl/bio.h>
+# include <ssl/bn.h>
+# include <ssl/dh.h>
+# include <ssl/pem.h>
+#endif /* HAVE_SSL */
+
+#include "entropy.h"
+#include "kex.h"
+
+Buffer *
+kex_init(char *myproposal[PROPOSAL_MAX])
+{
+        char c = 0;
+        unsigned char cookie[16];
+        u_int32_t rand = 0;
+        int i;
+        Buffer *ki = xmalloc(sizeof(*ki));
+        for (i = 0; i < 16; i++) {
+                if (i % 4 == 0)
+                        rand = arc4random();
+                cookie[i] = rand & 0xff;
+                rand >>= 8;
+        }
+        buffer_init(ki);
+        buffer_append(ki, (char *)cookie, sizeof cookie);
+        for (i = 0; i < PROPOSAL_MAX; i++)
+                buffer_put_cstring(ki, myproposal[i]);
+        buffer_append(ki, &c, 1); /* boolean   first_kex_packet_follows */
+        buffer_put_int(ki, 0);    /* uint32    0 (reserved for future extension) */
+        return ki;
+}
+
+/* diffie-hellman-group1-sha1 */
+
+DH *
+new_dh_group1()
+{
+        static char *group1 =
+            "FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1"
+            "29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD"
+            "EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245"
+            "E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED"
+            "EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE65381"
+            "FFFFFFFF" "FFFFFFFF";
+        DH *dh;
+        int ret;
+        dh = DH_new();
+        if(dh == NULL)
+                fatal("DH_new");
+        ret = BN_hex2bn(&dh->p,group1);
+        if(ret<0)
+                fatal("BN_hex2bn");
+        dh->g = BN_new();
+        if(dh->g == NULL)
+                fatal("DH_new g");
+        BN_set_word(dh->g,2);
+
+        seed_rng();
+        if (DH_generate_key(dh) == 0)
+                fatal("DH_generate_key");
+        seed_rng();
+
+        return dh;
+}
+
+void
+bignum_print(BIGNUM *b)
+{
+        BN_print_fp(stderr,b);
+}
+
+void
+dump_digest(unsigned char *digest, int len)
+{
+        int i;
+        for (i = 0; i< len; i++){
+                fprintf(stderr, "%02x", digest[i]);
+                if(i%2!=0)
+                        fprintf(stderr, " ");
+        }
+        fprintf(stderr, "\n");
+}
+
+unsigned char *
+kex_hash(
+    char *client_version_string,
+    char *server_version_string,
+    char *ckexinit, int ckexinitlen,
+    char *skexinit, int skexinitlen,
+    char *serverhostkeyblob, int sbloblen,
+    BIGNUM *client_dh_pub,
+    BIGNUM *server_dh_pub,
+    BIGNUM *shared_secret)
+{
+        Buffer b;
+        static unsigned char digest[EVP_MAX_MD_SIZE];
+        EVP_MD *evp_md = EVP_sha1();
+        EVP_MD_CTX md;
+
+        buffer_init(&b);
+        buffer_put_string(&b, client_version_string, strlen(client_version_string));
+        buffer_put_string(&b, server_version_string, strlen(server_version_string));
+
+        /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
+        buffer_put_int(&b, ckexinitlen+1);
+        buffer_put_char(&b, SSH2_MSG_KEXINIT);
+        buffer_append(&b, ckexinit, ckexinitlen);
+        buffer_put_int(&b, skexinitlen+1);
+        buffer_put_char(&b, SSH2_MSG_KEXINIT);
+        buffer_append(&b, skexinit, skexinitlen);
+
+        buffer_put_string(&b, serverhostkeyblob, sbloblen);
+        buffer_put_bignum2(&b, client_dh_pub);
+        buffer_put_bignum2(&b, server_dh_pub);
+        buffer_put_bignum2(&b, shared_secret);
+        
+#ifdef DEBUG_KEX
+        buffer_dump(&b);
+#endif
+
+        EVP_DigestInit(&md, evp_md);
+        EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
+        EVP_DigestFinal(&md, digest, NULL);
+
+        buffer_free(&b);
+
+#ifdef DEBUG_KEX
+        dump_digest(digest, evp_md->md_size);
+#endif
+        return digest;
+}
+
+unsigned char *
+derive_key(int id, int need, char unsigned *hash, BIGNUM *shared_secret)
+{
+        Buffer b;
+        EVP_MD *evp_md = EVP_sha1();
+        EVP_MD_CTX md;
+        char c = id;
+        int have;
+        int mdsz = evp_md->md_size;
+        unsigned char *digest = xmalloc(((need+mdsz-1)/mdsz)*mdsz);
+
+        buffer_init(&b);
+        buffer_put_bignum2(&b, shared_secret);
+
+        EVP_DigestInit(&md, evp_md);
+        EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));  /* shared_secret K */
+        EVP_DigestUpdate(&md, hash, mdsz);              /* transport-06 */
+        EVP_DigestUpdate(&md, &c, 1);                   /* key id */
+        EVP_DigestUpdate(&md, hash, mdsz);              /* session id */
+        EVP_DigestFinal(&md, digest, NULL);
+
+        /* expand */
+        for (have = mdsz; need > have; have += mdsz) {
+                EVP_DigestInit(&md, evp_md);
+                EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
+                EVP_DigestUpdate(&md, hash, mdsz);
+                EVP_DigestUpdate(&md, digest, have);
+                EVP_DigestFinal(&md, digest + have, NULL);
+        }
+        buffer_free(&b);
+#ifdef DEBUG_KEX
+        fprintf(stderr, "Digest '%c'== ", c);
+        dump_digest(digest, need);
+#endif
+        return digest;
+}
+
+#define NKEYS   6
+
+#define MAX_PROP        20
+#define SEP     ","
+
+char *
+get_match(char *client, char *server)
+{
+        char *sproposals[MAX_PROP];
+        char *p;
+        int i, j, nproposals;
+
+        for ((p = strtok(server, SEP)), i=0; p; (p = strtok(NULL, SEP)), i++) {
+                if (i < MAX_PROP)
+                        sproposals[i] = p;
+                else
+                        break;
+        }
+        nproposals = i;
+
+        for ((p = strtok(client, SEP)), i=0; p; (p = strtok(NULL, SEP)), i++) {
+                for (j = 0; j < nproposals; j++)
+                        if (strcmp(p, sproposals[j]) == 0)
+                                return xstrdup(p);
+        }
+        return NULL;
+}
+void
+choose_enc(Enc *enc, char *client, char *server)
+{
+        char *name = get_match(client, server);
+        if (name == NULL)
+                fatal("no matching cipher found: client %s server %s", client, server);
+        enc->type = cipher_number(name);
+
+        switch (enc->type) {
+        case SSH_CIPHER_3DES_CBC:
+                enc->key_len = 24;
+                enc->iv_len = 8;
+                enc->block_size = 8;
+                break;
+        case SSH_CIPHER_BLOWFISH_CBC:
+        case SSH_CIPHER_CAST128_CBC:
+                enc->key_len = 16;
+                enc->iv_len = 8;
+                enc->block_size = 8;
+                break;
+        case SSH_CIPHER_ARCFOUR:
+                enc->key_len = 16;
+                enc->iv_len = 0;
+                enc->block_size = 8;
+                break;
+        default:
+                fatal("unsupported cipher %s", name);
+        }
+        enc->name = name;
+        enc->enabled = 0;
+        enc->iv = NULL;
+        enc->key = NULL;
+}
+void
+choose_mac(Mac *mac, char *client, char *server)
+{
+        char *name = get_match(client, server);
+        if (name == NULL)
+                fatal("no matching mac found: client %s server %s", client, server);
+        if (strcmp(name, "hmac-md5") == 0) {
+                mac->md = EVP_md5();
+        } else if (strcmp(name, "hmac-sha1") == 0) {
+                mac->md = EVP_sha1();
+        } else if (strcmp(name, "hmac-ripemd160@openssh.com") == 0) {
+                mac->md = EVP_ripemd160();
+        } else {
+                fatal("unsupported mac %s", name);
+        }
+        mac->name = name;
+        mac->mac_len = mac->md->md_size;
+        mac->key_len = datafellows ? 16 : mac->mac_len;
+        mac->key = NULL;
+        mac->enabled = 0;
+}
+void
+choose_comp(Comp *comp, char *client, char *server)
+{
+        char *name = get_match(client, server);
+        if (name == NULL)
+                fatal("no matching comp found: client %s server %s", client, server);
+        if (strcmp(name, "zlib") == 0) {
+                comp->type = 1;
+        } else if (strcmp(name, "none") == 0) {
+                comp->type = 0;
+        } else {
+                fatal("unsupported comp %s", name);
+        }
+        comp->name = name;
+}
+void
+choose_kex(Kex *k, char *client, char *server)
+{
+        k->name = get_match(client, server);
+        if (k->name == NULL)
+                fatal("no kex alg");
+        if (strcmp(k->name, KEX_DH1) != 0)
+                fatal("bad kex alg %s", k->name);
+}
+void
+choose_hostkeyalg(Kex *k, char *client, char *server)
+{
+        k->hostkeyalg = get_match(client, server);
+        if (k->hostkeyalg == NULL)
+                fatal("no hostkey alg");
+        if (strcmp(k->hostkeyalg, KEX_DSS) != 0)
+                fatal("bad hostkey alg %s", k->hostkeyalg);
+}
+
+Kex *
+kex_choose_conf(char *cprop[PROPOSAL_MAX], char *sprop[PROPOSAL_MAX], int server)
+{
+        int i;
+        int mode;
+        int ctos;                               /* direction: if true client-to-server */
+        int need;
+        Kex *k;
+
+        k = xmalloc(sizeof(*k));
+        memset(k, 0, sizeof(*k));
+        k->server = server;
+
+        for (mode = 0; mode < MODE_MAX; mode++) {
+                int nenc, nmac, ncomp;
+                ctos = (!k->server && mode == MODE_OUT) || (k->server && mode == MODE_IN);
+                nenc  = ctos ? PROPOSAL_ENC_ALGS_CTOS  : PROPOSAL_ENC_ALGS_STOC;
+                nmac  = ctos ? PROPOSAL_MAC_ALGS_CTOS  : PROPOSAL_MAC_ALGS_STOC;
+                ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
+                choose_enc (&k->enc [mode], cprop[nenc],  sprop[nenc]);
+                choose_mac (&k->mac [mode], cprop[nmac],  sprop[nmac]);
+                choose_comp(&k->comp[mode], cprop[ncomp], sprop[ncomp]);
+                log("kex: %s %s %s %s",
+                    ctos ? "client->server" : "server->client",
+                    k->enc[mode].name,
+                    k->mac[mode].name,
+                    k->comp[mode].name);
+        }
+        choose_kex(k, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]);
+        choose_hostkeyalg(k, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
+            sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]);
+        for (i = 0; i < PROPOSAL_MAX; i++) {
+                xfree(cprop[i]);
+                xfree(sprop[i]);
+        }
+        need = 0;
+        for (mode = 0; mode < MODE_MAX; mode++) {
+            if (need < k->enc[mode].key_len)
+                    need = k->enc[mode].key_len;
+            if (need < k->enc[mode].iv_len)
+                    need = k->enc[mode].iv_len;
+            if (need < k->mac[mode].key_len)
+                    need = k->mac[mode].key_len;
+        }
+        /* need runden? */
+#define WE_NEED 32
+        k->we_need = WE_NEED;
+        k->we_need = need;
+        return k;
+}
+
+int
+kex_derive_keys(Kex *k, unsigned char *hash, BIGNUM *shared_secret)
+{
+        int i;
+        int mode;
+        int ctos;
+        unsigned char *keys[NKEYS];
+
+        for (i = 0; i < NKEYS; i++)
+                keys[i] = derive_key('A'+i, k->we_need, hash, shared_secret);
+
+        for (mode = 0; mode < MODE_MAX; mode++) {
+                ctos = (!k->server && mode == MODE_OUT) || (k->server && mode == MODE_IN);
+                k->enc[mode].iv  = keys[ctos ? 0 : 1];
+                k->enc[mode].key = keys[ctos ? 2 : 3];
+                k->mac[mode].key = keys[ctos ? 4 : 5];
+        }
+        return 0;
+}