[openssh.git] / gss-serv.c

/*	$OpenBSD: gss-serv.c,v 1.1 2003/08/22 10:56:09 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 "bufaux.h"
#include "compat.h"
#include "auth.h"
#include "log.h"
#include "channels.h"
#include "session.h"
#include "servconf.h"
#include "monitor_wrap.h"
#include "xmalloc.h"
#include "getput.h"

#include "ssh-gss.h"

extern ServerOptions options;

static ssh_gssapi_client gssapi_client =
    { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER,
    GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}};

ssh_gssapi_mech gssapi_null_mech =
    { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL};

#ifdef KRB5
extern ssh_gssapi_mech gssapi_kerberos_mech;
#endif

ssh_gssapi_mech* supported_mechs[]= {
#ifdef KRB5
	&gssapi_kerberos_mech,
#endif
	&gssapi_null_mech,
};

/* Unpriviledged */
void
ssh_gssapi_supported_oids(gss_OID_set *oidset)
{
	int i = 0;
	OM_uint32 min_status;
	int present;
	gss_OID_set supported;

	gss_create_empty_oid_set(&min_status, oidset);
	gss_indicate_mechs(&min_status, &supported);

	while (supported_mechs[i]->name != NULL) {
		if (GSS_ERROR(gss_test_oid_set_member(&min_status,
		    &supported_mechs[i]->oid, supported, &present)))
			present = 0;
		if (present)
			gss_add_oid_set_member(&min_status,
			    &supported_mechs[i]->oid, oidset);
		i++;
	}
}


/* Wrapper around accept_sec_context
 * Requires that the context contains:
 *    oid
 *    credentials	(from ssh_gssapi_acquire_cred)
 */
/* Priviledged */
OM_uint32
ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok,
    gss_buffer_desc *send_tok, OM_uint32 *flags)
{
	OM_uint32 status;
	gss_OID mech;

	ctx->major = gss_accept_sec_context(&ctx->minor,
	    &ctx->context, ctx->creds, recv_tok,
	    GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech,
	    send_tok, flags, NULL, &ctx->client_creds);

	if (GSS_ERROR(ctx->major))
		ssh_gssapi_error(ctx);

	if (ctx->client_creds)
		debug("Received some client credentials");
	else
		debug("Got no client credentials");

	status = ctx->major;

	/* Now, if we're complete and we have the right flags, then
	 * we flag the user as also having been authenticated
	 */

	if (((flags == NULL) || ((*flags & GSS_C_MUTUAL_FLAG) &&
	    (*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) {
		if (ssh_gssapi_getclient(ctx, &gssapi_client))
			fatal("Couldn't convert client name");
	}

	return (status);
}

/*
 * This parses an exported name, extracting the mechanism specific portion
 * to use for ACL checking. It verifies that the name belongs the mechanism
 * originally selected.
 */
static OM_uint32
ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name)
{
	char *tok;
	OM_uint32 offset;
	OM_uint32 oidl;
	
	tok=ename->value;
	
	/* 
	 * Check that ename is long enough for all of the fixed length 
	 * header, and that the initial ID bytes are correct
	 */

	if (ename->length<6 || memcmp(tok,"\x04\x01", 2)!=0) 
		return GSS_S_FAILURE;

	/*
	 * Extract the OID, and check it. Here GSSAPI breaks with tradition
	 * and does use the OID type and length bytes. To confuse things
	 * there are two lengths - the first including these, and the
	 * second without.
	 */

	oidl = GET_16BIT(tok+2); /* length including next two bytes */
	oidl = oidl-2; /* turn it into the _real_ length of the variable OID */

	/*
	 * Check the BER encoding for correct type and length, that the
	 * string is long enough and that the OID matches that in our context
	 */
	if (tok[4] != 0x06 || tok[5] != oidl ||
	    ename->length < oidl+6 ||        
	   !ssh_gssapi_check_oid(ctx,tok+6,oidl))
		return GSS_S_FAILURE;

	offset = oidl+6;
	
	if (ename->length < offset+4)
		return GSS_S_FAILURE;
		
	name->length = GET_32BIT(tok+offset);
	offset += 4;
	
	if (ename->length < offset+name->length)
        	return GSS_S_FAILURE;
	
	name->value = xmalloc(name->length);
	memcpy(name->value,tok+offset,name->length);
	
	return GSS_S_COMPLETE;
} 

/* Extract the client details from a given context. This can only reliably
 * be called once for a context */

/* Priviledged (called from accept_secure_ctx) */
OM_uint32
ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client)
{
	int i = 0;

	gss_buffer_desc ename;
	
	client->mech = NULL;

	while (supported_mechs[i]->name != NULL) {
		if (supported_mechs[i]->oid.length == ctx->oid->length &&
		    (memcmp(supported_mechs[i]->oid.elements,
		    ctx->oid->elements, ctx->oid->length) == 0))
			client->mech = supported_mechs[i];
		i++;
	}

	if (client->mech == NULL) 
		return GSS_S_FAILURE;
	
	if ((ctx->major = gss_display_name(&ctx->minor, ctx->client, 
	    &client->displayname, NULL))) {
	        ssh_gssapi_error(ctx);
	        return (ctx->major);
	}
	
	if ((ctx->major = gss_export_name(&ctx->minor, ctx->client, 
	    &ename))) {
		ssh_gssapi_error(ctx);
		return (ctx->major);
	}
	
	if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename,
	    &client->exportedname))) {
		return (ctx->major);
	}

	/* We can't copy this structure, so we just move the pointer to it */
	client->creds = ctx->client_creds;
	ctx->client_creds = GSS_C_NO_CREDENTIAL;
	return (ctx->major);
}

/* As user - called through fatal cleanup hook */
void
ssh_gssapi_cleanup_creds(void *ignored)
{
	if (gssapi_client.store.filename != NULL) {
		/* Unlink probably isn't sufficient */
		debug("removing gssapi cred file\"%s\"", gssapi_client.store.filename);
		unlink(gssapi_client.store.filename);
	}
}

/* As user */
void
ssh_gssapi_storecreds(void)
{
	if (gssapi_client.mech && gssapi_client.mech->storecreds) {
		(*gssapi_client.mech->storecreds)(&gssapi_client);
		if (options.gss_cleanup_creds)
			fatal_add_cleanup(ssh_gssapi_cleanup_creds, NULL);
	} else
		debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism");
}

/* This allows GSSAPI methods to do things to the childs environment based
 * on the passed authentication process and credentials.
 */
/* As user */
void
ssh_gssapi_do_child(char ***envp, u_int *envsizep)
{

	if (gssapi_client.store.envvar != NULL &&
	    gssapi_client.store.envval != NULL) {

		debug("Setting %s to %s", gssapi_client.store.envvar,
		gssapi_client.store.envval);
		child_set_env(envp, envsizep, gssapi_client.store.envvar,
		     gssapi_client.store.envval);
	}
}

/* Priviledged */
int
ssh_gssapi_userok(char *user)
{
	if (gssapi_client.exportedname.length == 0 ||
	    gssapi_client.exportedname.value == NULL) {
		debug("No suitable client data");
		return 0;
	}
	if (gssapi_client.mech && gssapi_client.mech->userok)
		return ((*gssapi_client.mech->userok)(&gssapi_client, user));
	else
		debug("ssh_gssapi_userok: Unknown GSSAPI mechanism");
	return (0);
}

#endif
Commit	Line	Data
7364bd04	1	/* $OpenBSD: gss-serv.c,v 1.1 2003/08/22 10:56:09 markus Exp $ */
	2
	3	/*
	4	* Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
	5	*
	6	* Redistribution and use in source and binary forms, with or without
	7	* modification, are permitted provided that the following conditions
	8	* are met:
	9	* 1. Redistributions of source code must retain the above copyright
	10	* notice, this list of conditions and the following disclaimer.
	11	* 2. Redistributions in binary form must reproduce the above copyright
	12	* notice, this list of conditions and the following disclaimer in the
	13	* documentation and/or other materials provided with the distribution.
	14	*
	15	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR
	16	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	17	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	18	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	19	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	20	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	21	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	22	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	23	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	24	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	25	*/
	26
	27	#include "includes.h"
	28
	29	#ifdef GSSAPI
	30
	31	#include "bufaux.h"
	32	#include "compat.h"
	33	#include "auth.h"
	34	#include "log.h"
	35	#include "channels.h"
	36	#include "session.h"
	37	#include "servconf.h"
	38	#include "monitor_wrap.h"
	39	#include "xmalloc.h"
	40	#include "getput.h"
	41
	42	#include "ssh-gss.h"
	43
	44	extern ServerOptions options;
	45
	46	static ssh_gssapi_client gssapi_client =
	47	{ GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER,
	48	GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}};
	49
	50	ssh_gssapi_mech gssapi_null_mech =
	51	{ NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL};
	52
	53	#ifdef KRB5
	54	extern ssh_gssapi_mech gssapi_kerberos_mech;
	55	#endif
	56
	57	ssh_gssapi_mech* supported_mechs[]= {
	58	#ifdef KRB5
	59	&gssapi_kerberos_mech,
	60	#endif
	61	&gssapi_null_mech,
	62	};
	63
	64	/* Unpriviledged */
65	void
66	ssh_gssapi_supported_oids(gss_OID_set *oidset)
67	{
68	int i = 0;
69	OM_uint32 min_status;
70	int present;
71	gss_OID_set supported;
72
73	gss_create_empty_oid_set(&min_status, oidset);
74	gss_indicate_mechs(&min_status, &supported);
75
76	while (supported_mechs[i]->name != NULL) {
77	if (GSS_ERROR(gss_test_oid_set_member(&min_status,
78	&supported_mechs[i]->oid, supported, &present)))
79	present = 0;
80	if (present)
81	gss_add_oid_set_member(&min_status,
82	&supported_mechs[i]->oid, oidset);
83	i++;
84	}
85	}
86
87
88	/* Wrapper around accept_sec_context
89	* Requires that the context contains:
90	* oid
91	* credentials (from ssh_gssapi_acquire_cred)
92	*/
93	/* Priviledged */
94	OM_uint32
95	ssh_gssapi_accept_ctx(Gssctxt ctx, gss_buffer_desc recv_tok,
96	gss_buffer_desc send_tok, OM_uint32 flags)
97	{
98	OM_uint32 status;
99	gss_OID mech;
100
101	ctx->major = gss_accept_sec_context(&ctx->minor,
102	&ctx->context, ctx->creds, recv_tok,
103	GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech,
104	send_tok, flags, NULL, &ctx->client_creds);
105
106	if (GSS_ERROR(ctx->major))
107	ssh_gssapi_error(ctx);
108
109	if (ctx->client_creds)
110	debug("Received some client credentials");
111	else
112	debug("Got no client credentials");
113
114	status = ctx->major;
115
116	/* Now, if we're complete and we have the right flags, then
117	* we flag the user as also having been authenticated
118	*/
119
120	if (((flags == NULL) \|\| ((*flags & GSS_C_MUTUAL_FLAG) &&
121	(*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) {
122	if (ssh_gssapi_getclient(ctx, &gssapi_client))
123	fatal("Couldn't convert client name");
124	}
125
126	return (status);
127	}
128
129	/*
130	* This parses an exported name, extracting the mechanism specific portion
131	* to use for ACL checking. It verifies that the name belongs the mechanism
132	* originally selected.
133	*/
134	static OM_uint32
135	ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name)
136	{
137	char *tok;
138	OM_uint32 offset;
139	OM_uint32 oidl;
140
141	tok=ename->value;
142
143	/*
144	* Check that ename is long enough for all of the fixed length
145	* header, and that the initial ID bytes are correct
146	*/
147
148	if (ename->length<6 \|\| memcmp(tok,"\x04\x01", 2)!=0)
149	return GSS_S_FAILURE;
150
151	/*
152	* Extract the OID, and check it. Here GSSAPI breaks with tradition
153	* and does use the OID type and length bytes. To confuse things
154	* there are two lengths - the first including these, and the
155	* second without.
156	*/
157
158	oidl = GET_16BIT(tok+2); /* length including next two bytes */
159	oidl = oidl-2; /* turn it into the _real_ length of the variable OID */
160
161	/*
162	* Check the BER encoding for correct type and length, that the
163	* string is long enough and that the OID matches that in our context
164	*/
165	if (tok[4] != 0x06 \|\| tok[5] != oidl \|\|
166	ename->length < oidl+6 \|\|
167	!ssh_gssapi_check_oid(ctx,tok+6,oidl))
168	return GSS_S_FAILURE;
169
170	offset = oidl+6;
171
172	if (ename->length < offset+4)
173	return GSS_S_FAILURE;
174
175	name->length = GET_32BIT(tok+offset);
176	offset += 4;
177
178	if (ename->length < offset+name->length)
179	return GSS_S_FAILURE;
180
181	name->value = xmalloc(name->length);
182	memcpy(name->value,tok+offset,name->length);
183
184	return GSS_S_COMPLETE;
185	}
186
187	/* Extract the client details from a given context. This can only reliably
188	* be called once for a context */
189
190	/* Priviledged (called from accept_secure_ctx) */
191	OM_uint32
192	ssh_gssapi_getclient(Gssctxt ctx, ssh_gssapi_client client)
193	{
194	int i = 0;
195
196	gss_buffer_desc ename;
197
198	client->mech = NULL;
199
200	while (supported_mechs[i]->name != NULL) {
201	if (supported_mechs[i]->oid.length == ctx->oid->length &&
202	(memcmp(supported_mechs[i]->oid.elements,
203	ctx->oid->elements, ctx->oid->length) == 0))
204	client->mech = supported_mechs[i];
205	i++;
206	}
207
208	if (client->mech == NULL)
209	return GSS_S_FAILURE;
210
211	if ((ctx->major = gss_display_name(&ctx->minor, ctx->client,
212	&client->displayname, NULL))) {
213	ssh_gssapi_error(ctx);
214	return (ctx->major);
215	}
216
217	if ((ctx->major = gss_export_name(&ctx->minor, ctx->client,
218	&ename))) {
219	ssh_gssapi_error(ctx);
220	return (ctx->major);
221	}
222
223	if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename,
224	&client->exportedname))) {
225	return (ctx->major);
226	}
227
228	/* We can't copy this structure, so we just move the pointer to it */
229	client->creds = ctx->client_creds;
230	ctx->client_creds = GSS_C_NO_CREDENTIAL;
231	return (ctx->major);
232	}
233
234	/* As user - called through fatal cleanup hook */
235	void
236	ssh_gssapi_cleanup_creds(void *ignored)
237	{
238	if (gssapi_client.store.filename != NULL) {
239	/* Unlink probably isn't sufficient */
240	debug("removing gssapi cred file\"%s\"", gssapi_client.store.filename);
241	unlink(gssapi_client.store.filename);
242	}
243	}
244
245	/* As user */
246	void
247	ssh_gssapi_storecreds(void)
248	{
249	if (gssapi_client.mech && gssapi_client.mech->storecreds) {
250	(*gssapi_client.mech->storecreds)(&gssapi_client);
251	if (options.gss_cleanup_creds)
252	fatal_add_cleanup(ssh_gssapi_cleanup_creds, NULL);
253	} else
254	debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism");
255	}
256
257	/* This allows GSSAPI methods to do things to the childs environment based
258	* on the passed authentication process and credentials.
259	*/
260	/* As user */
261	void
262	ssh_gssapi_do_child(char **envp, u_int envsizep)
263	{
264
265	if (gssapi_client.store.envvar != NULL &&
266	gssapi_client.store.envval != NULL) {
267
268	debug("Setting %s to %s", gssapi_client.store.envvar,
269	gssapi_client.store.envval);
270	child_set_env(envp, envsizep, gssapi_client.store.envvar,
271	gssapi_client.store.envval);
272	}
273	}
274
275	/* Priviledged */
276	int
277	ssh_gssapi_userok(char *user)
278	{
279	if (gssapi_client.exportedname.length == 0 \|\|
280	gssapi_client.exportedname.value == NULL) {
281	debug("No suitable client data");
282	return 0;
283	}
284	if (gssapi_client.mech && gssapi_client.mech->userok)
285	return ((*gssapi_client.mech->userok)(&gssapi_client, user));
286	else
287	debug("ssh_gssapi_userok: Unknown GSSAPI mechanism");
288	return (0);
289	}
290
291	#endif