1 /* $OpenBSD: gss-genr.c,v 1.20 2009/06/22 05:39:28 dtucker 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
45 extern u_char *session_id2;
46 extern u_int session_id2_len;
47
48 /* Check that the OID in a data stream matches that in the context */
49 int
ssh_gssapi_check_oid(Gssctxt * ctx,void * data,size_t len)50 ssh_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 */
58 void
ssh_gssapi_set_oid_data(Gssctxt * ctx,void * data,size_t len)59 ssh_gssapi_set_oid_data(Gssctxt *ctx, void *data, size_t len)
60 {
61 if (ctx->oid != GSS_C_NO_OID) {
62 xfree(ctx->oid->elements);
63 xfree(ctx->oid);
64 }
65 ctx->oid = xmalloc(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 */
72 void
ssh_gssapi_set_oid(Gssctxt * ctx,gss_OID oid)73 ssh_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 ... */
79 void
ssh_gssapi_error(Gssctxt * ctxt)80 ssh_gssapi_error(Gssctxt *ctxt)
81 {
82 char *s;
83
84 s = ssh_gssapi_last_error(ctxt, NULL, NULL);
85 debug("%s", s);
86 xfree(s);
87 }
88
89 char *
ssh_gssapi_last_error(Gssctxt * ctxt,OM_uint32 * major_status,OM_uint32 * minor_status)90 ssh_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 */
142 void
ssh_gssapi_build_ctx(Gssctxt ** ctx)143 ssh_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 */
155 void
ssh_gssapi_delete_ctx(Gssctxt ** ctx)156 ssh_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 xfree((*ctx)->oid->elements);
168 xfree((*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 xfree(*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 */
188 OM_uint32
ssh_gssapi_init_ctx(Gssctxt * ctx,int deleg_creds,gss_buffer_desc * recv_tok,gss_buffer_desc * send_tok,OM_uint32 * flags)189 ssh_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 */
211 OM_uint32
ssh_gssapi_import_name(Gssctxt * ctx,const char * host)212 ssh_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 xfree(gssbuf.value);
226 return (ctx->major);
227 }
228
229 OM_uint32
ssh_gssapi_sign(Gssctxt * ctx,gss_buffer_t buffer,gss_buffer_t hash)230 ssh_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
239 void
ssh_gssapi_buildmic(Buffer * b,const char * user,const char * service,const char * context)240 ssh_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
251 int
ssh_gssapi_check_mechanism(Gssctxt ** ctx,gss_OID oid,const char * host)252 ssh_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