1 files changed, 136 insertions, 10 deletions

diff --git a/sshconnect2.c b/sshconnect2.c
index dd971a9f9..63e9369b1 100644
--- a/sshconnect2.c
+++ b/sshconnect2.c
@@ -98,9 +98,34 @@ ssh_kex2(char *host, struct sockaddr *hostaddr)
 {
         Kex *kex;
 
+#ifdef GSSAPI
+        char *orig = NULL, *gss = NULL;
+        char *gss_host = NULL;
+#endif
+
         xxx_host = host;
         xxx_hostaddr = hostaddr;
 
+#ifdef GSSAPI
+        if (options.gss_keyex) {
+                /* Add the GSSAPI mechanisms currently supported on this 
+                 * client to the key exchange algorithm proposal */
+                orig = myproposal[PROPOSAL_KEX_ALGS];
+
+                if (options.gss_trust_dns)
+                        gss_host = (char *)get_canonical_hostname(1);
+                else
+                        gss_host = host;
+
+                gss = ssh_gssapi_client_mechanisms(gss_host);
+                if (gss) {
+                        debug("Offering GSSAPI proposal: %s", gss);
+                        xasprintf(&myproposal[PROPOSAL_KEX_ALGS],
+                            "%s,%s", gss, orig);
+                }
+        }
+#endif
+
         if (options.ciphers == (char *)-1) {
                 logit("No valid ciphers for protocol version 2 given, using defaults.");
                 options.ciphers = NULL;
@@ -128,6 +153,16 @@ ssh_kex2(char *host, struct sockaddr *hostaddr)
                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
                     options.hostkeyalgorithms;
 
+#ifdef GSSAPI
+        /* If we've got GSSAPI algorithms, then we also support the
+         * 'null' hostkey, as a last resort */
+        if (options.gss_keyex && gss) {
+                orig = myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS];
+                xasprintf(&myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS], 
+                    "%s,null", orig);
+        }
+#endif
+
         if (options.rekey_limit)
                 packet_set_rekey_limit(options.rekey_limit);
 
@@ -137,10 +172,23 @@ ssh_kex2(char *host, struct sockaddr *hostaddr)
         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
         kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
         kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
+#ifdef GSSAPI
+        if (options.gss_keyex) {
+                kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_client;
+                kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_client;
+                kex->kex[KEX_GSS_GEX_SHA1] = kexgss_client;
+        }
+#endif
         kex->client_version_string=client_version_string;
         kex->server_version_string=server_version_string;
         kex->verify_host_key=&verify_host_key_callback;
 
+#ifdef GSSAPI
+        kex->gss_deleg_creds = options.gss_deleg_creds;
+        kex->gss_trust_dns = options.gss_trust_dns;
+        kex->gss_host = gss_host;
+#endif
+
         xxx_kex = kex;
 
         dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
@@ -223,6 +271,7 @@ void	input_gssapi_token(int type, u_int32_t, void *);
 void    input_gssapi_hash(int type, u_int32_t, void *);
 void    input_gssapi_error(int, u_int32_t, void *);
 void    input_gssapi_errtok(int, u_int32_t, void *);
+int     userauth_gsskeyex(Authctxt *authctxt);
 #endif
 
 void    userauth(Authctxt *, char *);
@@ -238,10 +287,18 @@ static char *authmethods_get(void);
 
 Authmethod authmethods[] = {
 #ifdef GSSAPI
+        {"gssapi-keyex",
+                userauth_gsskeyex,
+                &options.gss_authentication,
+                NULL},
         {"gssapi-with-mic",
                 userauth_gssapi,
                 &options.gss_authentication,
                 NULL},
+        {"gssapi",
+                userauth_gssapi,
+                &options.gss_authentication,
+                NULL},
 #endif
         {"hostbased",
                 userauth_hostbased,
@@ -500,6 +557,13 @@ userauth_gssapi(Authctxt *authctxt)
         static u_int mech = 0;
         OM_uint32 min;
         int ok = 0;
+        char *gss_host = NULL;
+        int old_gssapi_method;
+
+        if (options.gss_trust_dns)
+                gss_host = (char *)get_canonical_hostname(1);
+        else
+                gss_host = (char *)authctxt->host;
 
         /* Try one GSSAPI method at a time, rather than sending them all at
          * once. */
@@ -512,7 +576,7 @@ userauth_gssapi(Authctxt *authctxt)
                 /* My DER encoding requires length<128 */
                 if (gss_supported->elements[mech].length < 128 &&
                     ssh_gssapi_check_mechanism(&gssctxt, 
-                    &gss_supported->elements[mech], authctxt->host)) {
+                    &gss_supported->elements[mech], gss_host)) {
                         ok = 1; /* Mechanism works */
                 } else {
                         mech++;
@@ -529,13 +593,25 @@ userauth_gssapi(Authctxt *authctxt)
         packet_put_cstring(authctxt->service);
         packet_put_cstring(authctxt->method->name);
 
-        packet_put_int(1);
+        old_gssapi_method = !strcmp(authctxt->method->name, "gssapi");
+
+        /* Versions of Debian ssh-krb5 prior to 3.8.1p1-1 don't expect
+         * tagged OIDs.  As such we include both tagged and untagged oids
+         * for the old gssapi method.
+         * We only include tagged oids for the new gssapi-with-mic method.
+         */
+        packet_put_int(old_gssapi_method ? 2 : 1);
 
         packet_put_int((gss_supported->elements[mech].length) + 2);
         packet_put_char(SSH_GSS_OIDTYPE);
         packet_put_char(gss_supported->elements[mech].length);
         packet_put_raw(gss_supported->elements[mech].elements,
             gss_supported->elements[mech].length);
+        if (old_gssapi_method) {
+                packet_put_int(gss_supported->elements[mech].length);
+                packet_put_raw(gss_supported->elements[mech].elements,
+                               gss_supported->elements[mech].length);
+        }
 
         packet_send();
 
@@ -575,8 +651,10 @@ process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
         }
 
         if (status == GSS_S_COMPLETE) {
+                int old_gssapi_method = !strcmp(authctxt->method->name,
+                                                "gssapi");
                 /* send either complete or MIC, depending on mechanism */
-                if (!(flags & GSS_C_INTEG_FLAG)) {
+                if (old_gssapi_method || !(flags & GSS_C_INTEG_FLAG)) {
                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
                         packet_send();
                 } else {
@@ -608,8 +686,8 @@ input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 {
         Authctxt *authctxt = ctxt;
         Gssctxt *gssctxt;
-        int oidlen;
-        char *oidv;
+        u_int oidlen;
+        u_char *oidv, *oidv_free;
 
         if (authctxt == NULL)
                 fatal("input_gssapi_response: no authentication context");
@@ -617,22 +695,28 @@ input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 
         /* Setup our OID */
         oidv = packet_get_string(&oidlen);
+        oidv_free = oidv;
 
         if (oidlen <= 2 ||
             oidv[0] != SSH_GSS_OIDTYPE ||
             oidv[1] != oidlen - 2) {
-                xfree(oidv);
                 debug("Badly encoded mechanism OID received");
-                userauth(authctxt, NULL);
-                return;
+                if (oidlen < 2) {
+                        xfree(oidv_free);
+                        userauth(authctxt, NULL);
+                        return;
+                }
+        } else {
+                oidlen -= 2;
+                oidv += 2;
         }
 
-        if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
+        if (!ssh_gssapi_check_oid(gssctxt, oidv, oidlen))
                 fatal("Server returned different OID than expected");
 
         packet_check_eom();
 
-        xfree(oidv);
+        xfree(oidv_free);
 
         if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
                 /* Start again with next method on list */
@@ -716,6 +800,48 @@ input_gssapi_error(int type, u_int32_t plen, void *ctxt)
         xfree(msg);
         xfree(lang);
 }
+
+int
+userauth_gsskeyex(Authctxt *authctxt)
+{
+        Buffer b;
+        gss_buffer_desc gssbuf;
+        gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
+        OM_uint32 ms;
+
+        static int attempt = 0;
+        if (attempt++ >= 1)
+                return (0);
+
+        if (gss_kex_context == NULL) {
+                debug("No valid Key exchange context"); 
+                return (0);
+        }
+
+        ssh_gssapi_buildmic(&b, authctxt->server_user, authctxt->service,
+            "gssapi-keyex");
+
+        gssbuf.value = buffer_ptr(&b);
+        gssbuf.length = buffer_len(&b);
+
+        if (GSS_ERROR(ssh_gssapi_sign(gss_kex_context, &gssbuf, &mic))) {
+                buffer_free(&b);
+                return (0);
+        }
+
+        packet_start(SSH2_MSG_USERAUTH_REQUEST);
+        packet_put_cstring(authctxt->server_user);
+        packet_put_cstring(authctxt->service);
+        packet_put_cstring(authctxt->method->name);
+        packet_put_string(mic.value, mic.length);
+        packet_send();
+
+        buffer_free(&b);
+        gss_release_buffer(&ms, &mic);
+
+        return (1);
+}
+
 #endif /* GSSAPI */
 
 int