1 /*
2 * This file and its contents are supplied under the terms of the
3 * Common Development and Distribution License ("CDDL"), version 1.0.
4 * You may only use this file in accordance with the terms of version
5 * 1.0 of the CDDL.
6 *
7 * A full copy of the text of the CDDL should have accompanied this
8 * source. A copy of the CDDL is also available via the Internet at
9 * http://www.illumos.org/license/CDDL.
10 */
11
12 /*
13 * Copyright 2015 Nexenta Systems, Inc. All rights reserved.
14 */
15
16 /*
17 * SPNEGO back-end for Kerberos. See [MS-KILE]
18 */
19
20 #include <sys/types.h>
21 #include <gssapi/gssapi_ext.h>
22 #include <gssapi/gssapi_krb5.h>
23 #include <krb5.h>
24 #include "smbd.h"
25 #include "smbd_authsvc.h"
26
27 /* From krb5/krb/pac.c (should have been exported) */
28 #define PAC_LOGON_INFO 1
29
30 typedef struct krb5ssp_backend {
31 gss_ctx_id_t be_gssctx;
32 char *be_username;
33 gss_buffer_desc be_authz_pac;
34 krb5_context be_kctx;
35 krb5_pac be_kpac;
36 krb5_data be_pac;
37 } krb5ssp_backend_t;
38
39 static uint32_t
40 get_authz_data_pac(
41 gss_ctx_id_t context_handle,
42 gss_buffer_t ad_data);
43
44 static uint32_t
45 get_ssnkey(authsvc_context_t *ctx);
46
47
48 /*
49 * Initialize this context for Kerberos, if possible.
50 *
51 * Should not get here unless libsmb smb_config_get_negtok
52 * includes the Kerberos5 Mech OIDs in our spnego hint.
53 *
54 * Todo: allocate ctx->ctx_backend
55 * See: krb5_gss_accept_sec_context()
56 */
57 int
58 smbd_krb5ssp_init(authsvc_context_t *ctx)
59 {
60 krb5ssp_backend_t *be;
61
62 be = malloc(sizeof (*be));
63 if (be == 0)
64 return (NT_STATUS_NO_MEMORY);
65 bzero(be, sizeof (*be));
66 be->be_gssctx = GSS_C_NO_CONTEXT;
67 ctx->ctx_backend = be;
68
69 return (0);
70 }
71
72 /*
73 * Todo: free ctx->ctx_backend
74 */
75 void
76 smbd_krb5ssp_fini(authsvc_context_t *ctx)
77 {
78 krb5ssp_backend_t *be = ctx->ctx_backend;
79 uint32_t minor;
80
81 if (be == NULL)
82 return;
83
84 if (be->be_kctx != NULL) {
85 krb5_free_data_contents(be->be_kctx, &be->be_pac);
86
87 if (be->be_kpac != NULL)
88 krb5_pac_free(be->be_kctx, be->be_kpac);
89
90 krb5_free_context(be->be_kctx);
91 }
92
93 (void) gss_release_buffer(NULL, &be->be_authz_pac);
94
95 free(be->be_username);
96
97 if (be->be_gssctx != GSS_C_NO_CONTEXT) {
98 (void) gss_delete_sec_context(&minor, &be->be_gssctx,
99 GSS_C_NO_BUFFER);
100 }
101
102 free(be);
103 }
104
105 /*
106 * Handle a Kerberos auth message.
107 *
108 * State across messages is in ctx->ctx_backend
109 */
110 int
111 smbd_krb5ssp_work(authsvc_context_t *ctx)
112 {
113 gss_buffer_desc intok, outtok;
114 gss_buffer_desc namebuf;
115 krb5ssp_backend_t *be = ctx->ctx_backend;
116 gss_name_t gname = NULL;
117 OM_uint32 major, minor, ret_flags;
118 gss_OID name_type = GSS_C_NULL_OID;
119 gss_OID mech_type = GSS_C_NULL_OID;
120 krb5_error_code kerr;
121 uint32_t status;
122
123 intok.length = ctx->ctx_ibodylen;
124 intok.value = ctx->ctx_ibodybuf;
125 bzero(&outtok, sizeof (gss_buffer_desc));
126 bzero(&namebuf, sizeof (gss_buffer_desc));
127
128 /* Do this early, for error message support. */
129 kerr = krb5_init_context(&be->be_kctx);
130 if (kerr != 0) {
131 smbd_report("krb5ssp, krb5_init_ctx: %s",
132 krb5_get_error_message(be->be_kctx, kerr));
133 return (NT_STATUS_INTERNAL_ERROR);
134 }
135
136 major = gss_accept_sec_context(&minor, &be->be_gssctx,
137 GSS_C_NO_CREDENTIAL, &intok,
138 GSS_C_NO_CHANNEL_BINDINGS, &gname, &mech_type, &outtok,
139 &ret_flags, NULL, NULL);
140
141 if (outtok.length == 0)
142 ctx->ctx_obodylen = 0;
143 else if (outtok.length <= ctx->ctx_obodylen) {
144 ctx->ctx_obodylen = outtok.length;
145 (void) memcpy(ctx->ctx_obodybuf, outtok.value, outtok.length);
146 free(outtok.value);
147 outtok.value = NULL;
148 } else {
149 free(ctx->ctx_obodybuf);
150 ctx->ctx_obodybuf = outtok.value;
151 ctx->ctx_obodylen = outtok.length;
152 outtok.value = NULL;
153 }
154
155 if (GSS_ERROR(major)) {
156 smbd_report("krb5ssp: gss_accept_sec_context, "
157 "mech=0x%x, major=0x%x, minor=0x%x",
158 (int)mech_type, major, minor);
159 smbd_report(" krb5: %s",
160 krb5_get_error_message(be->be_kctx, minor));
161 return (NT_STATUS_WRONG_PASSWORD);
162 }
163
164 switch (major) {
165 case GSS_S_COMPLETE:
166 break;
167 case GSS_S_CONTINUE_NEEDED:
168 if (outtok.length > 0) {
169 ctx->ctx_orawtype = LSA_MTYPE_ES_CONT;
170 /* becomes NT_STATUS_MORE_PROCESSING_REQUIRED */
171 return (0);
172 }
173 return (NT_STATUS_WRONG_PASSWORD);
174 default:
175 return (NT_STATUS_WRONG_PASSWORD);
176 }
177
178 /*
179 * OK, we got GSS_S_COMPLETE. Get the name so we can use it
180 * in log messages if we get failures decoding the PAC etc.
181 * Then get the PAC, decode it, build the logon token.
182 */
183
184 if (gname != NULL && GSS_S_COMPLETE ==
185 gss_display_name(&minor, gname, &namebuf, &name_type)) {
186 /* Save the user name. */
187 be->be_username = strdup(namebuf.value);
188 (void) gss_release_buffer(&minor, &namebuf);
189 (void) gss_release_name(&minor, &gname);
190 if (be->be_username == NULL) {
191 return (NT_STATUS_NO_MEMORY);
192 }
193 }
194
195 /*
196 * Extract the KRB5_AUTHDATA_WIN2K_PAC data.
197 */
198 status = get_authz_data_pac(be->be_gssctx,
199 &be->be_authz_pac);
200 if (status)
201 return (status);
202
203 kerr = krb5_pac_parse(be->be_kctx, be->be_authz_pac.value,
204 be->be_authz_pac.length, &be->be_kpac);
205 if (kerr) {
206 smbd_report("krb5ssp, krb5_pac_parse: %s",
207 krb5_get_error_message(be->be_kctx, kerr));
208 return (NT_STATUS_UNSUCCESSFUL);
209 }
210
211 kerr = krb5_pac_get_buffer(be->be_kctx, be->be_kpac,
212 PAC_LOGON_INFO, &be->be_pac);
213 if (kerr) {
214 smbd_report("krb5ssp, krb5_pac_get_buffer: %s",
215 krb5_get_error_message(be->be_kctx, kerr));
216 return (NT_STATUS_UNSUCCESSFUL);
217 }
218
219 ctx->ctx_token = calloc(1, sizeof (smb_token_t));
220 if (ctx->ctx_token == NULL)
221 return (NT_STATUS_NO_MEMORY);
222
223 status = smb_decode_krb5_pac(ctx->ctx_token, be->be_pac.data,
224 be->be_pac.length);
225 if (status)
226 return (status);
227
228 status = get_ssnkey(ctx);
229 if (status)
230 return (status);
231
232 if (!smb_token_setup_common(ctx->ctx_token))
233 return (NT_STATUS_UNSUCCESSFUL);
234
235 /* Success! */
236 ctx->ctx_orawtype = LSA_MTYPE_ES_DONE;
237
238 return (0);
239 }
240
241 /*
242 * See: GSS_KRB5_EXTRACT_AUTHZ_DATA_FROM_SEC_CONTEXT_OID
243 * and: KRB5_AUTHDATA_WIN2K_PAC
244 */
245 static const gss_OID_desc
246 oid_ex_authz_data_pac = {
247 13, "\x2a\x86\x48\x86\xf7\x12\x01\x02\x02\x05\x0a\x81\x00" };
248
249 /*
250 * See: krb5_gss_inquire_sec_context_by_oid()
251 * and krb5_gss_inquire_sec_context_by_oid_ops[],
252 * gss_krb5int_extract_authz_data_from_sec_context()
253 */
254 static uint32_t
255 get_authz_data_pac(
256 gss_ctx_id_t context_handle,
257 gss_buffer_t ad_data)
258 {
259 gss_buffer_set_t data_set = GSS_C_NO_BUFFER_SET;
260 OM_uint32 major, minor;
261 uint32_t status = NT_STATUS_UNSUCCESSFUL;
262
263 if (ad_data == NULL)
264 goto out;
265
266 major = gss_inquire_sec_context_by_oid(
267 &minor,
268 context_handle,
269 (gss_OID)&oid_ex_authz_data_pac,
270 &data_set);
271 if (GSS_ERROR(major)) {
272 smbd_report("krb5ssp, gss_inquire...PAC, "
273 "major=0x%x, minor=0x%x", major, minor);
274 goto out;
275 }
276
277 if ((data_set == GSS_C_NO_BUFFER_SET) || (data_set->count == 0)) {
278 goto out;
279 }
280
281 /* Only need the first element? */
282 ad_data->length = data_set->elements[0].length;
283 ad_data->value = malloc(ad_data->length);
284 if (ad_data->value == NULL) {
285 status = NT_STATUS_NO_MEMORY;
286 goto out;
287 }
288 bcopy(data_set->elements[0].value, ad_data->value, ad_data->length);
289 status = 0;
290
291 out:
292 (void) gss_release_buffer_set(&minor, &data_set);
293
294 return (status);
295 }
296
297 /*
298 * Get the session key, and save it in the token.
299 *
300 * See: krb5_gss_inquire_sec_context_by_oid(),
301 * krb5_gss_inquire_sec_context_by_oid_ops[], and
302 * gss_krb5int_inq_session_key
303 */
304 static uint32_t
305 get_ssnkey(authsvc_context_t *ctx)
306 {
307 krb5ssp_backend_t *be = ctx->ctx_backend;
308 gss_buffer_set_t data_set = GSS_C_NO_BUFFER_SET;
309 OM_uint32 major, minor;
310 size_t keylen;
311 uint32_t status = NT_STATUS_UNSUCCESSFUL;
312
313 major = gss_inquire_sec_context_by_oid(&minor,
314 be->be_gssctx, GSS_C_INQ_SSPI_SESSION_KEY, &data_set);
315 if (GSS_ERROR(major)) {
316 smbd_report("krb5ssp, failed to get session key, "
317 "major=0x%x, minor=0x%x", major, minor);
318 goto out;
319 }
320
321 /*
322 * The key is in the first element
323 */
324 if (data_set == GSS_C_NO_BUFFER_SET ||
325 data_set->count == 0 ||
326 data_set->elements[0].length == 0 ||
327 data_set->elements[0].value == NULL) {
328 smbd_report("krb5ssp: Session key is missing");
329 goto out;
330 }
331 if ((keylen = data_set->elements[0].length) < SMBAUTH_HASH_SZ) {
332 smbd_report("krb5ssp: Session key too short (%d)",
333 data_set->elements[0].length);
334 goto out;
335 }
336
337 ctx->ctx_token->tkn_ssnkey.val = malloc(keylen);
338 if (ctx->ctx_token->tkn_ssnkey.val == NULL) {
339 status = NT_STATUS_NO_MEMORY;
340 goto out;
341 }
342 ctx->ctx_token->tkn_ssnkey.len = keylen;
343 bcopy(data_set->elements[0].value,
344 ctx->ctx_token->tkn_ssnkey.val, keylen);
345 status = 0;
346
347 out:
348 (void) gss_release_buffer_set(&minor, &data_set);
349 return (status);
350 }