1/* $OpenBSD: gss-genr.c,v 1.22 2013/11/08 00:39:15 djm Exp $ */
2
3/*
4 * Copyright (c) 2001-2007 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 <sys/types.h>
32#include <sys/param.h>
33
34#include <stdarg.h>
35#include <string.h>
36#include <unistd.h>
37
38#include "xmalloc.h"
39#include "buffer.h"
40#include "log.h"
41#include "ssh2.h"
42
43#include "ssh-gss.h"
44
45extern u_char *session_id2;
46extern u_int session_id2_len;
47
48/* Check that the OID in a data stream matches that in the context */
49int
50ssh_gssapi_check_oid(Gssctxt *ctx, void *data, size_t len)
51{
52	return (ctx != NULL && ctx->oid != GSS_C_NO_OID &&
53	    ctx->oid->length == len &&
54	    memcmp(ctx->oid->elements, data, len) == 0);
55}
56
57/* Set the contexts OID from a data stream */
58void
59ssh_gssapi_set_oid_data(Gssctxt *ctx, void *data, size_t len)
60{
61	if (ctx->oid != GSS_C_NO_OID) {
62		free(ctx->oid->elements);
63		free(ctx->oid);
64	}
65	ctx->oid = xcalloc(1, sizeof(gss_OID_desc));
66	ctx->oid->length = len;
67	ctx->oid->elements = xmalloc(len);
68	memcpy(ctx->oid->elements, data, len);
69}
70
71/* Set the contexts OID */
72void
73ssh_gssapi_set_oid(Gssctxt *ctx, gss_OID oid)
74{
75	ssh_gssapi_set_oid_data(ctx, oid->elements, oid->length);
76}
77
78/* All this effort to report an error ... */
79void
80ssh_gssapi_error(Gssctxt *ctxt)
81{
82	char *s;
83
84	s = ssh_gssapi_last_error(ctxt, NULL, NULL);
85	debug("%s", s);
86	free(s);
87}
88
89char *
90ssh_gssapi_last_error(Gssctxt *ctxt, OM_uint32 *major_status,
91    OM_uint32 *minor_status)
92{
93	OM_uint32 lmin;
94	gss_buffer_desc msg = GSS_C_EMPTY_BUFFER;
95	OM_uint32 ctx;
96	Buffer b;
97	char *ret;
98
99	buffer_init(&b);
100
101	if (major_status != NULL)
102		*major_status = ctxt->major;
103	if (minor_status != NULL)
104		*minor_status = ctxt->minor;
105
106	ctx = 0;
107	/* The GSSAPI error */
108	do {
109		gss_display_status(&lmin, ctxt->major,
110		    GSS_C_GSS_CODE, ctxt->oid, &ctx, &msg);
111
112		buffer_append(&b, msg.value, msg.length);
113		buffer_put_char(&b, '\n');
114
115		gss_release_buffer(&lmin, &msg);
116	} while (ctx != 0);
117
118	/* The mechanism specific error */
119	do {
120		gss_display_status(&lmin, ctxt->minor,
121		    GSS_C_MECH_CODE, ctxt->oid, &ctx, &msg);
122
123		buffer_append(&b, msg.value, msg.length);
124		buffer_put_char(&b, '\n');
125
126		gss_release_buffer(&lmin, &msg);
127	} while (ctx != 0);
128
129	buffer_put_char(&b, '\0');
130	ret = xmalloc(buffer_len(&b));
131	buffer_get(&b, ret, buffer_len(&b));
132	buffer_free(&b);
133	return (ret);
134}
135
136/*
137 * Initialise our GSSAPI context. We use this opaque structure to contain all
138 * of the data which both the client and server need to persist across
139 * {accept,init}_sec_context calls, so that when we do it from the userauth
140 * stuff life is a little easier
141 */
142void
143ssh_gssapi_build_ctx(Gssctxt **ctx)
144{
145	*ctx = xcalloc(1, sizeof (Gssctxt));
146	(*ctx)->context = GSS_C_NO_CONTEXT;
147	(*ctx)->name = GSS_C_NO_NAME;
148	(*ctx)->oid = GSS_C_NO_OID;
149	(*ctx)->creds = GSS_C_NO_CREDENTIAL;
150	(*ctx)->client = GSS_C_NO_NAME;
151	(*ctx)->client_creds = GSS_C_NO_CREDENTIAL;
152}
153
154/* Delete our context, providing it has been built correctly */
155void
156ssh_gssapi_delete_ctx(Gssctxt **ctx)
157{
158	OM_uint32 ms;
159
160	if ((*ctx) == NULL)
161		return;
162	if ((*ctx)->context != GSS_C_NO_CONTEXT)
163		gss_delete_sec_context(&ms, &(*ctx)->context, GSS_C_NO_BUFFER);
164	if ((*ctx)->name != GSS_C_NO_NAME)
165		gss_release_name(&ms, &(*ctx)->name);
166	if ((*ctx)->oid != GSS_C_NO_OID) {
167		free((*ctx)->oid->elements);
168		free((*ctx)->oid);
169		(*ctx)->oid = GSS_C_NO_OID;
170	}
171	if ((*ctx)->creds != GSS_C_NO_CREDENTIAL)
172		gss_release_cred(&ms, &(*ctx)->creds);
173	if ((*ctx)->client != GSS_C_NO_NAME)
174		gss_release_name(&ms, &(*ctx)->client);
175	if ((*ctx)->client_creds != GSS_C_NO_CREDENTIAL)
176		gss_release_cred(&ms, &(*ctx)->client_creds);
177
178	free(*ctx);
179	*ctx = NULL;
180}
181
182/*
183 * Wrapper to init_sec_context
184 * Requires that the context contains:
185 *	oid
186 *	server name (from ssh_gssapi_import_name)
187 */
188OM_uint32
189ssh_gssapi_init_ctx(Gssctxt *ctx, int deleg_creds, gss_buffer_desc *recv_tok,
190    gss_buffer_desc* send_tok, OM_uint32 *flags)
191{
192	int deleg_flag = 0;
193
194	if (deleg_creds) {
195		deleg_flag = GSS_C_DELEG_FLAG;
196		debug("Delegating credentials");
197	}
198
199	ctx->major = gss_init_sec_context(&ctx->minor,
200	    GSS_C_NO_CREDENTIAL, &ctx->context, ctx->name, ctx->oid,
201	    GSS_C_MUTUAL_FLAG | GSS_C_INTEG_FLAG | deleg_flag,
202	    0, NULL, recv_tok, NULL, send_tok, flags, NULL);
203
204	if (GSS_ERROR(ctx->major))
205		ssh_gssapi_error(ctx);
206
207	return (ctx->major);
208}
209
210/* Create a service name for the given host */
211OM_uint32
212ssh_gssapi_import_name(Gssctxt *ctx, const char *host)
213{
214	gss_buffer_desc gssbuf;
215	char *val;
216
217	xasprintf(&val, "host@%s", host);
218	gssbuf.value = val;
219	gssbuf.length = strlen(gssbuf.value);
220
221	if ((ctx->major = gss_import_name(&ctx->minor,
222	    &gssbuf, GSS_C_NT_HOSTBASED_SERVICE, &ctx->name)))
223		ssh_gssapi_error(ctx);
224
225	free(gssbuf.value);
226	return (ctx->major);
227}
228
229OM_uint32
230ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_t buffer, gss_buffer_t hash)
231{
232	if ((ctx->major = gss_get_mic(&ctx->minor, ctx->context,
233	    GSS_C_QOP_DEFAULT, buffer, hash)))
234		ssh_gssapi_error(ctx);
235
236	return (ctx->major);
237}
238
239void
240ssh_gssapi_buildmic(Buffer *b, const char *user, const char *service,
241    const char *context)
242{
243	buffer_init(b);
244	buffer_put_string(b, session_id2, session_id2_len);
245	buffer_put_char(b, SSH2_MSG_USERAUTH_REQUEST);
246	buffer_put_cstring(b, user);
247	buffer_put_cstring(b, service);
248	buffer_put_cstring(b, context);
249}
250
251int
252ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host)
253{
254	gss_buffer_desc token = GSS_C_EMPTY_BUFFER;
255	OM_uint32 major, minor;
256	gss_OID_desc spnego_oid = {6, (void *)"\x2B\x06\x01\x05\x05\x02"};
257
258	/* RFC 4462 says we MUST NOT do SPNEGO */
259	if (oid->length == spnego_oid.length &&
260	    (memcmp(oid->elements, spnego_oid.elements, oid->length) == 0))
261		return 0; /* false */
262
263	ssh_gssapi_build_ctx(ctx);
264	ssh_gssapi_set_oid(*ctx, oid);
265	major = ssh_gssapi_import_name(*ctx, host);
266	if (!GSS_ERROR(major)) {
267		major = ssh_gssapi_init_ctx(*ctx, 0, GSS_C_NO_BUFFER, &token,
268		    NULL);
269		gss_release_buffer(&minor, &token);
270		if ((*ctx)->context != GSS_C_NO_CONTEXT)
271			gss_delete_sec_context(&minor, &(*ctx)->context,
272			    GSS_C_NO_BUFFER);
273	}
274
275	if (GSS_ERROR(major))
276		ssh_gssapi_delete_ctx(ctx);
277
278	return (!GSS_ERROR(major));
279}
280
281#endif /* GSSAPI */
282