- markus@cvs.openbsd.org 2003/11/17 11:06:07

[auth2-gss.c gss-genr.c gss-serv.c monitor.c monitor.h monitor_wrap.c] [monitor_wrap.h sshconnect2.c ssh-gss.h] replace "gssapi" with "gssapi-with-mic"; from Simon Wilkinson; test + ok jakob.
2025-01-12 04:39:28 +00:00 · 2003-11-17 22:18:21 +11:00 · 2003-11-17 22:18:21 +11:00 · 0425d40194
commit 0425d40194
parent c756e9b56e
10 changed files with 191 additions and 29 deletions
--- a/7
+++ b/7
@ -43,6 +43,11 @@
   - djm@cvs.openbsd.org 2003/11/17 09:45:39
     [msg.c msg.h sshconnect2.c ssh-keysign.c]
     return error on msg send/receive failure (rather than fatal); ok markus@
+   - markus@cvs.openbsd.org 2003/11/17 11:06:07
+     [auth2-gss.c gss-genr.c gss-serv.c monitor.c monitor.h monitor_wrap.c]
+     [monitor_wrap.h sshconnect2.c ssh-gss.h]
+     replace "gssapi" with "gssapi-with-mic"; from Simon Wilkinson; 
+     test + ok jakob.
 - (djm) Bug #632: Don't call pam_end indirectly from within kbd-int
   conversation function
 - (djm) Export environment variables from authentication subprocess to 
@ -1467,4 +1472,4 @@
 - Fix sshd BindAddress and -b options for systems using fake-getaddrinfo.
   Report from murple@murple.net, diagnosis from dtucker@zip.com.au

-$Id: ChangeLog,v 1.3111 2003/11/17 10:41:42 djm Exp $
+$Id: ChangeLog,v 1.3112 2003/11/17 11:18:21 djm Exp $
--- a/auth2-gss.c
+++ b/auth2-gss.c
@ -1,4 +1,4 @@
-/*	$OpenBSD: auth2-gss.c,v 1.5 2003/11/02 11:01:03 markus Exp $	*/
+/*	$OpenBSD: auth2-gss.c,v 1.6 2003/11/17 11:06:07 markus Exp $	*/

 /*
 * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
@ -43,6 +43,7 @@
 extern ServerOptions options;

 static void input_gssapi_token(int type, u_int32_t plen, void *ctxt);
+static void input_gssapi_mic(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 *);

@ -129,7 +130,7 @@ input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 	Gssctxt *gssctxt;
 	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 	gss_buffer_desc recv_tok;
-	OM_uint32 maj_status, min_status;
+	OM_uint32 maj_status, min_status, flags;
 	u_int len;

 	if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
@ -142,7 +143,7 @@ input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 	packet_check_eom();

 	maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
-	    &send_tok, NULL));
+	    &send_tok, &flags));

 	xfree(recv_tok.value);

@ -154,7 +155,7 @@ input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 		}
 		authctxt->postponed = 0;
 		dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
-		userauth_finish(authctxt, 0, "gssapi");
+		userauth_finish(authctxt, 0, "gssapi-with-mic");
 	} else {
 		if (send_tok.length != 0) {
 			packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
@ -163,8 +164,13 @@ input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 		}
 		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);
+			if (flags & GSS_C_INTEG_FLAG)
+				dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC,
+				    &input_gssapi_mic);
+			else
+				dispatch_set(
+				    SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE,
+				    &input_gssapi_exchange_complete);
 		}
 	}

@ -224,9 +230,8 @@ input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt)
 	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.
+	 * We don't need to check the status, because we're only enabled in
+	 * the dispatcher once the exchange is complete
 	 */

 	packet_check_eom();
@ -236,12 +241,53 @@ input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt)
 	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_MIC, NULL);
 	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
-	userauth_finish(authctxt, authenticated, "gssapi");
+	userauth_finish(authctxt, authenticated, "gssapi-with-mic");
+}
+
+static void
+input_gssapi_mic(int type, u_int32_t plen, void *ctxt)
+{
+	Authctxt *authctxt = ctxt;
+	Gssctxt *gssctxt;
+	int authenticated = 0;
+	Buffer b;
+	gss_buffer_desc mic, gssbuf;
+	u_int len;
+	
+	if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
+		fatal("No authentication or GSSAPI context");
+	
+	gssctxt = authctxt->methoddata;
+	
+	mic.value = packet_get_string(&len);
+	mic.length = len;
+	
+	ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service,
+	    "gssapi-with-mic");
+	
+	gssbuf.value = buffer_ptr(&b);
+	gssbuf.length = buffer_len(&b);
+	
+	if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic))))
+		authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
+	else
+		logit("GSSAPI MIC check failed");
+
+	buffer_free(&b);
+	xfree(mic.value);
+	
+	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_MIC, NULL);
+	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
+	userauth_finish(authctxt, authenticated, "gssapi-with-mic");
 }

 Authmethod method_gssapi = {
-	"gssapi",
+	"gssapi-with-mic",
 	userauth_gssapi,
 	&options.gss_authentication
 };
--- a/gss-genr.c
+++ b/gss-genr.c
@ -1,4 +1,4 @@
-/*	$OpenBSD: gss-genr.c,v 1.1 2003/08/22 10:56:09 markus Exp $	*/
+/*	$OpenBSD: gss-genr.c,v 1.2 2003/11/17 11:06:07 markus Exp $	*/

 /*
 * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
@ -33,9 +33,12 @@
 #include "compat.h"
 #include "log.h"
 #include "monitor_wrap.h"
+#include "ssh2.h"

 #include "ssh-gss.h"

+extern u_char *session_id2;
+extern u_int session_id2_len;

 /* Check that the OID in a data stream matches that in the context */
 int
@ -244,6 +247,28 @@ ssh_gssapi_acquire_cred(Gssctxt *ctx)
 	return (ctx->major);
 }

+OM_uint32
+ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_t buffer, gss_buffer_t hash)
+{
+	if ((ctx->major = gss_get_mic(&ctx->minor, ctx->context,
+	    GSS_C_QOP_DEFAULT, buffer, hash)))
+		ssh_gssapi_error(ctx);
+	
+	return (ctx->major);
+}
+
+void
+ssh_gssapi_buildmic(Buffer *b, const char *user, const char *service, 
+    const char *context) 
+{	
+	buffer_init(b);
+	buffer_put_string(b, session_id2, session_id2_len);
+	buffer_put_char(b, SSH2_MSG_USERAUTH_REQUEST);
+	buffer_put_cstring(b, user);
+	buffer_put_cstring(b, service);
+	buffer_put_cstring(b, context);
+}
+
 OM_uint32
 ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid) {
 	if (*ctx)
--- a/gss-serv.c
+++ b/gss-serv.c
@ -1,4 +1,4 @@
-/*	$OpenBSD: gss-serv.c,v 1.4 2003/09/23 20:17:11 markus Exp $	*/
+/*	$OpenBSD: gss-serv.c,v 1.5 2003/11/17 11:06:07 markus Exp $	*/

 /*
 * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
@ -287,4 +287,14 @@ ssh_gssapi_userok(char *user)
 	return (0);
 }

+/* Priviledged */
+OM_uint32
+ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
+{
+	ctx->major = gss_verify_mic(&ctx->minor, ctx->context,
+	    gssbuf, gssmic, NULL);
+
+	return (ctx->major);
+}
+
 #endif
--- a/monitor.c
+++ b/monitor.c
@ -25,7 +25,7 @@
 */

 #include "includes.h"
-RCSID("$OpenBSD: monitor.c,v 1.51 2003/11/04 08:54:09 djm Exp $");
+RCSID("$OpenBSD: monitor.c,v 1.52 2003/11/17 11:06:07 markus Exp $");

 #include <openssl/dh.h>

@ -134,6 +134,7 @@ int mm_answer_pam_free_ctx(int, Buffer *);
 int mm_answer_gss_setup_ctx(int, Buffer *);
 int mm_answer_gss_accept_ctx(int, Buffer *);
 int mm_answer_gss_userok(int, Buffer *);
+int mm_answer_gss_checkmic(int, Buffer *);
 #endif

 static Authctxt *authctxt;
@ -193,6 +194,7 @@ struct mon_table mon_dispatch_proto20[] = {
    {MONITOR_REQ_GSSSETUP, MON_ISAUTH, mm_answer_gss_setup_ctx},
    {MONITOR_REQ_GSSSTEP, MON_ISAUTH, mm_answer_gss_accept_ctx},
    {MONITOR_REQ_GSSUSEROK, MON_AUTH, mm_answer_gss_userok},
+    {MONITOR_REQ_GSSCHECKMIC, MON_ISAUTH, mm_answer_gss_checkmic},
 #endif
    {0, 0, NULL}
 };
@ -1781,14 +1783,42 @@ mm_answer_gss_accept_ctx(int socket, Buffer *m)

 	gss_release_buffer(&minor, &out);

-	/* Complete - now we can do signing */
 	if (major==GSS_S_COMPLETE) {
 		monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 0);
 		monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1);
+		monitor_permit(mon_dispatch, MONITOR_REQ_GSSCHECKMIC, 1);
 	}
 	return (0);
 }

+int
+mm_answer_gss_checkmic(int socket, Buffer *m)
+{
+	gss_buffer_desc gssbuf, mic;
+	OM_uint32 ret;
+	u_int len;
+	
+	gssbuf.value = buffer_get_string(m, &len);
+	gssbuf.length = len;
+	mic.value = buffer_get_string(m, &len);
+	mic.length = len;
+	
+	ret = ssh_gssapi_checkmic(gsscontext, &gssbuf, &mic);
+	
+	xfree(gssbuf.value);
+	xfree(mic.value);
+	
+	buffer_clear(m);
+	buffer_put_int(m, ret);
+	
+	mm_request_send(socket, MONITOR_ANS_GSSCHECKMIC, m);
+	
+	if (!GSS_ERROR(ret))
+		monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1);
+	
+	return (0);
+}
+
 int
 mm_answer_gss_userok(int socket, Buffer *m)
 {
@ -1802,7 +1832,7 @@ mm_answer_gss_userok(int socket, Buffer *m)
 	debug3("%s: sending result %d", __func__, authenticated);
 	mm_request_send(socket, MONITOR_ANS_GSSUSEROK, m);

-	auth_method="gssapi";
+	auth_method="gssapi-with-mic";

 	/* Monitor loop will terminate if authenticated */
 	return (authenticated);
--- a/monitor.h
+++ b/monitor.h
@ -1,4 +1,4 @@
-/*	$OpenBSD: monitor.h,v 1.12 2003/09/23 20:17:11 markus Exp $	*/
+/*	$OpenBSD: monitor.h,v 1.13 2003/11/17 11:06:07 markus Exp $	*/

 /*
 * Copyright 2002 Niels Provos <provos@citi.umich.edu>
@ -52,6 +52,7 @@ enum monitor_reqtype {
 	MONITOR_REQ_GSSSETUP, MONITOR_ANS_GSSSETUP,
 	MONITOR_REQ_GSSSTEP, MONITOR_ANS_GSSSTEP,
 	MONITOR_REQ_GSSUSEROK, MONITOR_ANS_GSSUSEROK,
+	MONITOR_REQ_GSSCHECKMIC, MONITOR_ANS_GSSCHECKMIC,
 	MONITOR_REQ_PAM_START,
 	MONITOR_REQ_PAM_ACCOUNT, MONITOR_ANS_PAM_ACCOUNT,
 	MONITOR_REQ_PAM_INIT_CTX, MONITOR_ANS_PAM_INIT_CTX,
--- a/monitor_wrap.c
+++ b/monitor_wrap.c
@ -25,7 +25,7 @@
 */

 #include "includes.h"
-RCSID("$OpenBSD: monitor_wrap.c,v 1.34 2003/10/15 09:48:45 markus Exp $");
+RCSID("$OpenBSD: monitor_wrap.c,v 1.35 2003/11/17 11:06:07 markus Exp $");

 #include <openssl/bn.h>
 #include <openssl/dh.h>
@ -1134,6 +1134,25 @@ mm_ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *in,
 	return (major);
 }

+OM_uint32
+mm_ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
+{
+	Buffer m;
+	OM_uint32 major;
+
+	buffer_init(&m);
+	buffer_put_string(&m, gssbuf->value, gssbuf->length);
+	buffer_put_string(&m, gssmic->value, gssmic->length);
+
+	mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSCHECKMIC, &m);
+	mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_GSSCHECKMIC,
+	    &m);
+
+	major = buffer_get_int(&m);
+	buffer_free(&m);
+	return(major);
+}
+
 int
 mm_ssh_gssapi_userok(char *user)
 {
--- a/monitor_wrap.h
+++ b/monitor_wrap.h
@ -1,4 +1,4 @@
-/*	$OpenBSD: monitor_wrap.h,v 1.12 2003/09/23 20:17:11 markus Exp $	*/
+/*	$OpenBSD: monitor_wrap.h,v 1.13 2003/11/17 11:06:07 markus Exp $	*/

 /*
 * Copyright 2002 Niels Provos <provos@citi.umich.edu>
@ -62,6 +62,7 @@ OM_uint32 mm_ssh_gssapi_server_ctx(Gssctxt **ctxt, gss_OID oid);
 OM_uint32 mm_ssh_gssapi_accept_ctx(Gssctxt *ctxt,
   gss_buffer_desc *recv, gss_buffer_desc *send, OM_uint32 *flags);
 int mm_ssh_gssapi_userok(char *user);
+OM_uint32 mm_ssh_gssapi_checkmic(Gssctxt *, gss_buffer_t, gss_buffer_t);
 #endif

 #ifdef USE_PAM
--- a/ssh-gss.h
+++ b/ssh-gss.h
@ -1,4 +1,4 @@
-/*	$OpenBSD: ssh-gss.h,v 1.3 2003/10/02 08:26:53 markus Exp $	*/
+/*	$OpenBSD: ssh-gss.h,v 1.4 2003/11/17 11:06:07 markus Exp $	*/
 /*
 * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
 *
@ -50,6 +50,7 @@
 #define SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE	63
 #define SSH2_MSG_USERAUTH_GSSAPI_ERROR			64
 #define SSH2_MSG_USERAUTH_GSSAPI_ERRTOK			65
+#define SSH2_MSG_USERAUTH_GSSAPI_MIC			66

 #define SSH_GSS_OIDTYPE 0x06

@ -108,11 +109,13 @@ void ssh_gssapi_error(Gssctxt *ctx);
 char *ssh_gssapi_last_error(Gssctxt *ctxt, OM_uint32 *maj, OM_uint32 *min);
 void ssh_gssapi_build_ctx(Gssctxt **ctx);
 void ssh_gssapi_delete_ctx(Gssctxt **ctx);
+OM_uint32 ssh_gssapi_sign(Gssctxt *, gss_buffer_t, gss_buffer_t);
 OM_uint32 ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid);
+void ssh_gssapi_buildmic(Buffer *, const char *, const char *, const char *);

 /* In the server */
 int ssh_gssapi_userok(char *name);
-
+OM_uint32 ssh_gssapi_checkmic(Gssctxt *, gss_buffer_t, gss_buffer_t);
 void ssh_gssapi_do_child(char ***envp, u_int *envsizep);
 void ssh_gssapi_cleanup_creds(void);
 void ssh_gssapi_storecreds(void);
--- a/sshconnect2.c
+++ b/sshconnect2.c
@ -23,7 +23,7 @@
 */

 #include "includes.h"
-RCSID("$OpenBSD: sshconnect2.c,v 1.131 2003/11/17 09:45:39 djm Exp $");
+RCSID("$OpenBSD: sshconnect2.c,v 1.132 2003/11/17 11:06:07 markus Exp $");

 #include "openbsd-compat/sys-queue.h"

@ -222,7 +222,7 @@ static char *authmethods_get(void);

 Authmethod authmethods[] = {
 #ifdef GSSAPI
-	{"gssapi",
+	{"gssapi-with-mic",
 		userauth_gssapi,
 		&options.gss_authentication,
 		NULL},
@ -543,10 +543,12 @@ process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 	Authctxt *authctxt = ctxt;
 	Gssctxt *gssctxt = authctxt->methoddata;
 	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
-	OM_uint32 status, ms;
+	gss_buffer_desc gssbuf, mic;
+	OM_uint32 status, ms, flags;
+	Buffer b;
 	
 	status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
-	    recv_tok, &send_tok, NULL);
+	    recv_tok, &send_tok, &flags);

 	if (send_tok.length > 0) {
 		if (GSS_ERROR(status))
@ -560,9 +562,29 @@ process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 	}
 	
 	if (status == GSS_S_COMPLETE) {
-		/* If that succeeded, send a exchange complete message */
-		packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
-		packet_send();
+		/* send either complete or MIC, depending on mechanism */
+		if (!(flags & GSS_C_INTEG_FLAG)) {
+			packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
+			packet_send();
+		} else {
+			ssh_gssapi_buildmic(&b, authctxt->server_user,
+			    authctxt->service, "gssapi-with-mic");
+
+			gssbuf.value = buffer_ptr(&b);
+			gssbuf.length = buffer_len(&b);
+			
+			status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
+			
+			if (!GSS_ERROR(status)) {
+				packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
+				packet_put_string(mic.value, mic.length);
+				
+				packet_send();
+			}
+				
+			buffer_free(&b);
+			gss_release_buffer(&ms, &mic);
+		}	   
 	}
 	
 	return status;