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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 | |
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 | |
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 | |
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 | |
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 * | |
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 | |
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 | |
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 | |
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 | |
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 | |
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 | |
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 | |
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 */ |