X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=blobdiff_plain;f=ssh.c;h=288616fd901c6756bac358f98e5618220ed9f283;hb=af1460d6e5044a3344aaacd15c91cfdcb58578e7;hp=c93942361e9224658dc355b35ba70d6dcd27abdf;hpb=e0252a4a609a67db82515e674067d346606c7397;p=PuTTY.git

diff --git a/ssh.c b/ssh.c
index c9394236..288616fd 100644
--- a/ssh.c
+++ b/ssh.c
@@ -364,6 +364,7 @@ static void do_ssh2_authconn(Ssh ssh, const unsigned char *in, int inlen,
 			     struct Packet *pktin);
 static void ssh2_channel_check_close(struct ssh_channel *c);
 static void ssh_channel_destroy(struct ssh_channel *c);
+static void ssh2_msg_something_unimplemented(Ssh ssh, struct Packet *pktin);
 
 /*
  * Buffer management constants. There are several of these for
@@ -1834,6 +1835,15 @@ static struct Packet *ssh2_rdpkt(Ssh ssh, const unsigned char **data,
 	}
     }
 
+    /*
+     * RFC 4253 doesn't explicitly say that completely empty packets
+     * with no type byte are forbidden, so treat them as deserving
+     * an SSH_MSG_UNIMPLEMENTED.
+     */
+    if (st->pktin->length <= 5) { /* == 5 we hope, but robustness */
+        ssh2_msg_something_unimplemented(ssh, st->pktin);
+        crStop(NULL);
+    }
     /*
      * pktin->body and pktin->length should identify the semantic
      * content of the packet, excluding the initial type byte.
@@ -3007,6 +3017,10 @@ static void ssh_send_verstring(Ssh ssh, const char *protoname, char *svers)
     }
 
     ssh_fix_verstring(verstring + strlen(protoname));
+#ifdef FUZZING
+    /* FUZZING make PuTTY insecure, so make live use difficult. */
+    verstring[0] = 'I';
+#endif
 
     if (ssh->version == 2) {
 	size_t len;
@@ -3586,6 +3600,21 @@ static void ssh_hostport_setup(const char *host, int port, Conf *conf,
     }
 }
 
+static int ssh_test_for_upstream(const char *host, int port, Conf *conf)
+{
+    char *savedhost;
+    int savedport;
+    int ret;
+
+    random_ref(); /* platform may need this to determine share socket name */
+    ssh_hostport_setup(host, port, conf, &savedhost, &savedport, NULL);
+    ret = ssh_share_test_for_upstream(savedhost, savedport, conf);
+    sfree(savedhost);
+    random_unref();
+
+    return ret;
+}
+
 /*
  * Connect to specified host and port.
  * Returns an error message, or NULL on success.
@@ -4025,6 +4054,9 @@ static int do_ssh1_login(Ssh ssh, const unsigned char *in, int inlen,
                                             "rsa", keystr, fingerprint,
                                             ssh_dialog_callback, ssh);
             sfree(keystr);
+#ifdef FUZZING
+	    s->dlgret = 1;
+#endif
             if (s->dlgret < 0) {
                 do {
                     crReturn(0);
@@ -6462,6 +6494,11 @@ static void do_ssh2_transport(Ssh ssh, const void *vin, int inlen,
 	/* List encryption algorithms (client->server then server->client). */
 	for (k = KEXLIST_CSCIPHER; k <= KEXLIST_SCCIPHER; k++) {
 	    warn = FALSE;
+#ifdef FUZZING
+	    alg = ssh2_kexinit_addalg(s->kexlists[k], "none");
+	    alg->u.cipher.cipher = NULL;
+	    alg->u.cipher.warn = warn;
+#endif /* FUZZING */
 	    for (i = 0; i < s->n_preferred_ciphers; i++) {
 		const struct ssh2_ciphers *c = s->preferred_ciphers[i];
 		if (!c) warn = TRUE;
@@ -6475,6 +6512,11 @@ static void do_ssh2_transport(Ssh ssh, const void *vin, int inlen,
 	}
 	/* List MAC algorithms (client->server then server->client). */
 	for (j = KEXLIST_CSMAC; j <= KEXLIST_SCMAC; j++) {
+#ifdef FUZZING
+	    alg = ssh2_kexinit_addalg(s->kexlists[j], "none");
+	    alg->u.mac.mac = NULL;
+	    alg->u.mac.etm = FALSE;
+#endif /* FUZZING */
 	    for (i = 0; i < s->nmacs; i++) {
 		alg = ssh2_kexinit_addalg(s->kexlists[j], s->maclist[i]->name);
 		alg->u.mac.mac = s->maclist[i];
@@ -6747,8 +6789,8 @@ static void do_ssh2_transport(Ssh ssh, const void *vin, int inlen,
         {
             int csbits, scbits;
 
-            csbits = s->cscipher_tobe->real_keybits;
-            scbits = s->sccipher_tobe->real_keybits;
+            csbits = s->cscipher_tobe ? s->cscipher_tobe->real_keybits : 0;
+            scbits = s->sccipher_tobe ? s->sccipher_tobe->real_keybits : 0;
             s->nbits = (csbits > scbits ? csbits : scbits);
         }
         /* The keys only have hlen-bit entropy, since they're based on
@@ -7088,8 +7130,10 @@ static void do_ssh2_transport(Ssh ssh, const void *vin, int inlen,
 	!ssh->hostkey->verifysig(s->hkey, s->sigdata, s->siglen,
 				 (char *)s->exchange_hash,
 				 ssh->kex->hash->hlen)) {
+#ifndef FUZZING
 	bombout(("Server's host key did not match the signature supplied"));
 	crStopV;
+#endif
     }
 
     s->keystr = ssh->hostkey->fmtkey(s->hkey);
@@ -7114,6 +7158,9 @@ static void do_ssh2_transport(Ssh ssh, const void *vin, int inlen,
                                             ssh->hostkey->keytype, s->keystr,
                                             s->fingerprint,
                                             ssh_dialog_callback, ssh);
+#ifdef FUZZING
+	    s->dlgret = 1;
+#endif
             if (s->dlgret < 0) {
                 do {
                     crReturnV;
@@ -7146,8 +7193,10 @@ static void do_ssh2_transport(Ssh ssh, const void *vin, int inlen,
          * the one we saw before.
          */
         if (strcmp(ssh->hostkey_str, s->keystr)) {
+#ifndef FUZZING
             bombout(("Host key was different in repeat key exchange"));
             crStopV;
+#endif
         }
         sfree(s->keystr);
     }
@@ -7181,13 +7230,14 @@ static void do_ssh2_transport(Ssh ssh, const void *vin, int inlen,
     if (ssh->cs_cipher_ctx)
 	ssh->cscipher->free_context(ssh->cs_cipher_ctx);
     ssh->cscipher = s->cscipher_tobe;
-    ssh->cs_cipher_ctx = ssh->cscipher->make_context();
+    if (ssh->cscipher) ssh->cs_cipher_ctx = ssh->cscipher->make_context();
 
     if (ssh->cs_mac_ctx)
 	ssh->csmac->free_context(ssh->cs_mac_ctx);
     ssh->csmac = s->csmac_tobe;
     ssh->csmac_etm = s->csmac_etm_tobe;
-    ssh->cs_mac_ctx = ssh->csmac->make_context(ssh->cs_cipher_ctx);
+    if (ssh->csmac)
+        ssh->cs_mac_ctx = ssh->csmac->make_context(ssh->cs_cipher_ctx);
 
     if (ssh->cs_comp_ctx)
 	ssh->cscomp->compress_cleanup(ssh->cs_comp_ctx);
@@ -7198,7 +7248,7 @@ static void do_ssh2_transport(Ssh ssh, const void *vin, int inlen,
      * Set IVs on client-to-server keys. Here we use the exchange
      * hash from the _first_ key exchange.
      */
-    {
+    if (ssh->cscipher) {
 	unsigned char *key;
 
 	key = ssh2_mkkey(ssh, s->K, s->exchange_hash, 'C',
@@ -7212,6 +7262,9 @@ static void do_ssh2_transport(Ssh ssh, const void *vin, int inlen,
 	ssh->cscipher->setiv(ssh->cs_cipher_ctx, key);
         smemclr(key, ssh->cscipher->blksize);
         sfree(key);
+    }
+    if (ssh->csmac) {
+	unsigned char *key;
 
 	key = ssh2_mkkey(ssh, s->K, s->exchange_hash, 'E',
                          ssh->csmac->keylen);
@@ -7220,12 +7273,14 @@ static void do_ssh2_transport(Ssh ssh, const void *vin, int inlen,
         sfree(key);
     }
 
-    logeventf(ssh, "Initialised %.200s client->server encryption",
-	      ssh->cscipher->text_name);
-    logeventf(ssh, "Initialised %.200s client->server MAC algorithm%s%s",
-	      ssh->csmac->text_name,
-              ssh->csmac_etm ? " (in ETM mode)" : "",
-              ssh->cscipher->required_mac ? " (required by cipher)" : "");
+    if (ssh->cscipher)
+	logeventf(ssh, "Initialised %.200s client->server encryption",
+		  ssh->cscipher->text_name);
+    if (ssh->csmac)
+	logeventf(ssh, "Initialised %.200s client->server MAC algorithm%s%s",
+		  ssh->csmac->text_name,
+		  ssh->csmac_etm ? " (in ETM mode)" : "",
+		  ssh->cscipher->required_mac ? " (required by cipher)" : "");
     if (ssh->cscomp->text_name)
 	logeventf(ssh, "Initialised %s compression",
 		  ssh->cscomp->text_name);
@@ -7253,14 +7308,18 @@ static void do_ssh2_transport(Ssh ssh, const void *vin, int inlen,
      */
     if (ssh->sc_cipher_ctx)
 	ssh->sccipher->free_context(ssh->sc_cipher_ctx);
-    ssh->sccipher = s->sccipher_tobe;
-    ssh->sc_cipher_ctx = ssh->sccipher->make_context();
+    if (ssh->sccipher) {
+	ssh->sccipher = s->sccipher_tobe;
+	ssh->sc_cipher_ctx = ssh->sccipher->make_context();
+    }
 
     if (ssh->sc_mac_ctx)
 	ssh->scmac->free_context(ssh->sc_mac_ctx);
-    ssh->scmac = s->scmac_tobe;
-    ssh->scmac_etm = s->scmac_etm_tobe;
-    ssh->sc_mac_ctx = ssh->scmac->make_context(ssh->sc_cipher_ctx);
+    if (ssh->scmac) {
+	ssh->scmac = s->scmac_tobe;
+	ssh->scmac_etm = s->scmac_etm_tobe;
+	ssh->sc_mac_ctx = ssh->scmac->make_context(ssh->sc_cipher_ctx);
+    }
 
     if (ssh->sc_comp_ctx)
 	ssh->sccomp->decompress_cleanup(ssh->sc_comp_ctx);
@@ -7271,7 +7330,7 @@ static void do_ssh2_transport(Ssh ssh, const void *vin, int inlen,
      * Set IVs on server-to-client keys. Here we use the exchange
      * hash from the _first_ key exchange.
      */
-    {
+    if (ssh->sccipher) {
 	unsigned char *key;
 
 	key = ssh2_mkkey(ssh, s->K, s->exchange_hash, 'D',
@@ -7285,6 +7344,9 @@ static void do_ssh2_transport(Ssh ssh, const void *vin, int inlen,
 	ssh->sccipher->setiv(ssh->sc_cipher_ctx, key);
         smemclr(key, ssh->sccipher->blksize);
         sfree(key);
+    }
+    if (ssh->scmac) {
+	unsigned char *key;
 
 	key = ssh2_mkkey(ssh, s->K, s->exchange_hash, 'F',
                          ssh->scmac->keylen);
@@ -7292,12 +7354,14 @@ static void do_ssh2_transport(Ssh ssh, const void *vin, int inlen,
         smemclr(key, ssh->scmac->keylen);
         sfree(key);
     }
-    logeventf(ssh, "Initialised %.200s server->client encryption",
-	      ssh->sccipher->text_name);
-    logeventf(ssh, "Initialised %.200s server->client MAC algorithm%s%s",
-	      ssh->scmac->text_name,
-              ssh->scmac_etm ? " (in ETM mode)" : "",
-              ssh->sccipher->required_mac ? " (required by cipher)" : "");
+    if (ssh->sccipher)
+	logeventf(ssh, "Initialised %.200s server->client encryption",
+		  ssh->sccipher->text_name);
+    if (ssh->scmac)
+	logeventf(ssh, "Initialised %.200s server->client MAC algorithm%s%s",
+		  ssh->scmac->text_name,
+		  ssh->scmac_etm ? " (in ETM mode)" : "",
+		  ssh->sccipher->required_mac ? " (required by cipher)" : "");
     if (ssh->sccomp->text_name)
 	logeventf(ssh, "Initialised %s decompression",
 		  ssh->sccomp->text_name);
@@ -11645,6 +11709,7 @@ Backend ssh_backend = {
     ssh_provide_logctx,
     ssh_unthrottle,
     ssh_cfg_info,
+    ssh_test_for_upstream,
     "ssh",
     PROT_SSH,
     22