]> asedeno.scripts.mit.edu Git - PuTTY.git/blobdiff - ssh.c
Add FUZZING support to ssh.c.
[PuTTY.git] / ssh.c
diff --git a/ssh.c b/ssh.c
index f56e10a9f11c1f1d441595e07599bf8195c787d1..288616fd901c6756bac358f98e5618220ed9f283 100644 (file)
--- 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;
@@ -3549,35 +3563,20 @@ static void ssh_sent(Plug plug, int bufsize)
        ssh_throttle_all(ssh, 0, bufsize);
 }
 
-/*
- * Connect to specified host and port.
- * Returns an error message, or NULL on success.
- * Also places the canonical host name into `realhost'. It must be
- * freed by the caller.
- */
-static const char *connect_to_host(Ssh ssh, const char *host, int port,
-                                  char **realhost, int nodelay, int keepalive)
+static void ssh_hostport_setup(const char *host, int port, Conf *conf,
+                               char **savedhost, int *savedport,
+                               char **loghost_ret)
 {
-    static const struct plug_function_table fn_table = {
-       ssh_socket_log,
-       ssh_closing,
-       ssh_receive,
-       ssh_sent,
-       NULL
-    };
+    char *loghost = conf_get_str(conf, CONF_loghost);
+    if (loghost_ret)
+        *loghost_ret = loghost;
 
-    SockAddr addr;
-    const char *err;
-    char *loghost;
-    int addressfamily, sshprot;
-    
-    loghost = conf_get_str(ssh->conf, CONF_loghost);
     if (*loghost) {
        char *tmphost;
         char *colon;
 
         tmphost = dupstr(loghost);
-       ssh->savedport = 22;           /* default ssh port */
+       *savedport = 22;               /* default ssh port */
 
        /*
         * A colon suffix on the hostname string also lets us affect
@@ -3588,17 +3587,58 @@ static const char *connect_to_host(Ssh ssh, const char *host, int port,
        if (colon && colon == host_strchr(tmphost, ':')) {
            *colon++ = '\0';
            if (*colon)
-               ssh->savedport = atoi(colon);
+               *savedport = atoi(colon);
        }
 
-        ssh->savedhost = host_strduptrim(tmphost);
+        *savedhost = host_strduptrim(tmphost);
         sfree(tmphost);
     } else {
-       ssh->savedhost = host_strduptrim(host);
+       *savedhost = host_strduptrim(host);
        if (port < 0)
            port = 22;                 /* default ssh port */
-       ssh->savedport = port;
+       *savedport = port;
     }
+}
+
+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.
+ * Also places the canonical host name into `realhost'. It must be
+ * freed by the caller.
+ */
+static const char *connect_to_host(Ssh ssh, const char *host, int port,
+                                  char **realhost, int nodelay, int keepalive)
+{
+    static const struct plug_function_table fn_table = {
+       ssh_socket_log,
+       ssh_closing,
+       ssh_receive,
+       ssh_sent,
+       NULL
+    };
+
+    SockAddr addr;
+    const char *err;
+    char *loghost;
+    int addressfamily, sshprot;
+
+    ssh_hostport_setup(host, port, ssh->conf,
+                       &ssh->savedhost, &ssh->savedport, &loghost);
 
     ssh->fn = &fn_table;               /* make 'ssh' usable as a Plug */
 
@@ -4014,6 +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);
@@ -6451,6 +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;
@@ -6464,6 +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];
@@ -6568,6 +6621,24 @@ static void do_ssh2_transport(Ssh ssh, const void *vin, int inlen,
                bombout(("KEXINIT packet was incomplete"));
                crStopV;
            }
+
+            /* If we've already selected a cipher which requires a
+             * particular MAC, then just select that, and don't even
+             * bother looking through the server's KEXINIT string for
+             * MACs. */
+            if (i == KEXLIST_CSMAC && s->cscipher_tobe &&
+                s->cscipher_tobe->required_mac) {
+                s->csmac_tobe = s->cscipher_tobe->required_mac;
+                s->csmac_etm_tobe = !!(s->csmac_tobe->etm_name);
+                goto matched;
+            }
+            if (i == KEXLIST_SCMAC && s->sccipher_tobe &&
+                s->sccipher_tobe->required_mac) {
+                s->scmac_tobe = s->sccipher_tobe->required_mac;
+                s->scmac_etm_tobe = !!(s->scmac_tobe->etm_name);
+                goto matched;
+            }
+
            for (j = 0; j < MAXKEXLIST; j++) {
                struct kexinit_algorithm *alg = &s->kexlists[i][j];
                if (alg->name == NULL) break;
@@ -6613,16 +6684,6 @@ static void do_ssh2_transport(Ssh ssh, const void *vin, int inlen,
          matched:;
        }
 
-        /* If the cipher over-rides the mac, then pick it */
-        if (s->cscipher_tobe && s->cscipher_tobe->required_mac) {
-            s->csmac_tobe = s->cscipher_tobe->required_mac;
-           s->csmac_etm_tobe = !!(s->csmac_tobe->etm_name);
-        }
-        if (s->sccipher_tobe && s->sccipher_tobe->required_mac) {
-            s->scmac_tobe = s->sccipher_tobe->required_mac;
-           s->scmac_etm_tobe = !!(s->scmac_tobe->etm_name);
-        }
-
        if (s->pending_compression) {
            logevent("Server supports delayed compression; "
                     "will try this later");
@@ -6728,8 +6789,8 @@ static void do_ssh2_transport(Ssh ssh, const void *vin, int inlen,
         {
             int csbits, scbits;
 
-            csbits = s->cscipher_tobe->keylen;
-            scbits = s->sccipher_tobe->keylen;
+            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
@@ -7069,8 +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);
@@ -7095,6 +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;
@@ -7127,8 +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);
     }
@@ -7162,13 +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);
@@ -7179,13 +7248,13 @@ 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',
-                         (ssh->cscipher->keylen+7) / 8);
+                         ssh->cscipher->padded_keybytes);
        ssh->cscipher->setkey(ssh->cs_cipher_ctx, key);
-        smemclr(key, (ssh->cscipher->keylen+7) / 8);
+        smemclr(key, ssh->cscipher->padded_keybytes);
         sfree(key);
 
        key = ssh2_mkkey(ssh, s->K, s->exchange_hash, 'A',
@@ -7193,6 +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);
@@ -7201,12 +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);
@@ -7234,14 +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);
@@ -7252,13 +7330,13 @@ 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',
-                         (ssh->sccipher->keylen + 7) / 8);
+                         ssh->sccipher->padded_keybytes);
        ssh->sccipher->setkey(ssh->sc_cipher_ctx, key);
-        smemclr(key, (ssh->sccipher->keylen + 7) / 8);
+        smemclr(key, ssh->sccipher->padded_keybytes);
         sfree(key);
 
        key = ssh2_mkkey(ssh, s->K, s->exchange_hash, 'B',
@@ -7266,6 +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);
@@ -7273,12 +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);
@@ -11626,6 +11709,7 @@ Backend ssh_backend = {
     ssh_provide_logctx,
     ssh_unthrottle,
     ssh_cfg_info,
+    ssh_test_for_upstream,
     "ssh",
     PROT_SSH,
     22