- markus@cvs.openbsd.org 2003/08/22 10:56:09
[auth2.c auth2-gss.c auth.h compat.c compat.h gss-genr.c gss-serv-krb5.c
gss-serv.c monitor.c monitor.h monitor_wrap.c monitor_wrap.h readconf.c
readconf.h servconf.c servconf.h session.c session.h ssh-gss.h
ssh_config.5 sshconnect2.c sshd_config sshd_config.5]
support GSS API user authentication; patches from Simon Wilkinson,
stripped down and tested by Jakob and myself.
diff --git a/auth2-gss.c b/auth2-gss.c
new file mode 100644
index 0000000..c765111
--- /dev/null
+++ b/auth2-gss.c
@@ -0,0 +1,243 @@
+/* $OpenBSD: auth2-gss.c,v 1.1 2003/08/22 10:56:08 markus Exp $ */
+
+/*
+ * Copyright (c) 2001-2003 Simon Wilkinson. 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.
+ *
+ * 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"
+
+#ifdef GSSAPI
+
+#include "auth.h"
+#include "ssh2.h"
+#include "xmalloc.h"
+#include "log.h"
+#include "dispatch.h"
+#include "servconf.h"
+#include "compat.h"
+#include "packet.h"
+#include "monitor_wrap.h"
+
+#include "ssh-gss.h"
+
+extern ServerOptions options;
+
+static void input_gssapi_token(int type, u_int32_t plen, void *ctxt);
+static void input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt);
+static void input_gssapi_errtok(int, u_int32_t, void *);
+
+/*
+ * We only support those mechanisms that we know about (ie ones that we know
+ * how to check local user kuserok and the like
+ */
+static int
+userauth_gssapi(Authctxt *authctxt)
+{
+ gss_OID_desc oid = {0, NULL};
+ Gssctxt *ctxt = NULL;
+ int mechs;
+ gss_OID_set supported;
+ int present;
+ OM_uint32 ms;
+ u_int len;
+ char *doid = NULL;
+
+ if (!authctxt->valid || authctxt->user == NULL)
+ return (0);
+
+ mechs = packet_get_int();
+ if (mechs == 0) {
+ debug("Mechanism negotiation is not supported");
+ return (0);
+ }
+
+ ssh_gssapi_supported_oids(&supported);
+ do {
+ mechs--;
+
+ if (doid)
+ xfree(doid);
+
+ doid = packet_get_string(&len);
+
+ if (doid[0] != SSH_GSS_OIDTYPE || doid[1] != len-2) {
+ logit("Mechanism OID received using the old encoding form");
+ oid.elements = doid;
+ oid.length = len;
+ } else {
+ oid.elements = doid + 2;
+ oid.length = len - 2;
+ }
+ gss_test_oid_set_member(&ms, &oid, supported, &present);
+ } while (mechs > 0 && !present);
+
+ gss_release_oid_set(&ms, &supported);
+
+ if (!present) {
+ xfree(doid);
+ return (0);
+ }
+
+ if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &oid))))
+ return (0);
+
+ authctxt->methoddata=(void *)ctxt;
+
+ packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE);
+
+ /* Return OID in same format as we received it*/
+ packet_put_string(doid, len);
+
+ packet_send();
+ xfree(doid);
+
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
+ authctxt->postponed = 1;
+
+ return (0);
+}
+
+static void
+input_gssapi_token(int type, u_int32_t plen, void *ctxt)
+{
+ Authctxt *authctxt = ctxt;
+ Gssctxt *gssctxt;
+ gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
+ gss_buffer_desc recv_tok;
+ OM_uint32 maj_status, min_status;
+ u_int len;
+
+ if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
+ fatal("No authentication or GSSAPI context");
+
+ gssctxt = authctxt->methoddata;
+ recv_tok.value = packet_get_string(&len);
+ recv_tok.length = len; /* u_int vs. size_t */
+
+ packet_check_eom();
+
+ maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
+ &send_tok, NULL));
+
+ xfree(recv_tok.value);
+
+ if (GSS_ERROR(maj_status)) {
+ if (send_tok.length != 0) {
+ packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
+ packet_put_string(send_tok.value, send_tok.length);
+ packet_send();
+ }
+ authctxt->postponed = 0;
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
+ userauth_finish(authctxt, 0, "gssapi");
+ } else {
+ if (send_tok.length != 0) {
+ packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
+ packet_put_string(send_tok.value, send_tok.length);
+ packet_send();
+ }
+ if (maj_status == GSS_S_COMPLETE) {
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE,
+ &input_gssapi_exchange_complete);
+ }
+ }
+
+ gss_release_buffer(&min_status, &send_tok);
+}
+
+static void
+input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
+{
+ Authctxt *authctxt = ctxt;
+ Gssctxt *gssctxt;
+ gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
+ gss_buffer_desc recv_tok;
+ OM_uint32 maj_status;
+
+ if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
+ fatal("No authentication or GSSAPI context");
+
+ gssctxt = authctxt->methoddata;
+ recv_tok.value = packet_get_string(&recv_tok.length);
+
+ packet_check_eom();
+
+ /* Push the error token into GSSAPI to see what it says */
+ maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
+ &send_tok, NULL));
+
+ xfree(recv_tok.value);
+
+ /* We can't return anything to the client, even if we wanted to */
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
+
+ /* The client will have already moved on to the next auth */
+
+ gss_release_buffer(&maj_status, &send_tok);
+}
+
+/*
+ * This is called when the client thinks we've completed authentication.
+ * It should only be enabled in the dispatch handler by the function above,
+ * which only enables it once the GSSAPI exchange is complete.
+ */
+
+static void
+input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt)
+{
+ Authctxt *authctxt = ctxt;
+ Gssctxt *gssctxt;
+ int authenticated;
+
+ if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
+ fatal("No authentication or GSSAPI context");
+
+ gssctxt = authctxt->methoddata;
+
+ /*
+ * We don't need to check the status, because the stored credentials
+ * which userok uses are only populated once the context init step
+ * has returned complete.
+ */
+
+ packet_check_eom();
+
+ authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
+
+ authctxt->postponed = 0;
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
+ userauth_finish(authctxt, authenticated, "gssapi");
+}
+
+Authmethod method_gssapi = {
+ "gssapi",
+ userauth_gssapi,
+ &options.gss_authentication
+};
+
+#endif /* GSSAPI */