1/* $OpenBSD: gss-serv.c,v 1.13 2005/10/13 22:24:31 stevesk 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 "auth.h"
33#include "log.h"
34#include "channels.h"
35#include "session.h"
36#include "servconf.h"
37#include "xmalloc.h"
38#include "getput.h"
39
40#include "ssh-gss.h"
41
42static ssh_gssapi_client gssapi_client =
43 { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER,
44 GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}};
45
46ssh_gssapi_mech gssapi_null_mech =
47 { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL};
48
49#ifdef KRB5
50extern ssh_gssapi_mech gssapi_kerberos_mech;
51#endif
52
53ssh_gssapi_mech* supported_mechs[]= {
54#ifdef KRB5
55 &gssapi_kerberos_mech,
56#endif
57 &gssapi_null_mech,
58};
59
60/* Unprivileged */
61void
62ssh_gssapi_supported_oids(gss_OID_set *oidset)
63{
64 int i = 0;
65 OM_uint32 min_status;
66 int present;
67 gss_OID_set supported;
68
69 gss_create_empty_oid_set(&min_status, oidset);
70 gss_indicate_mechs(&min_status, &supported);
71
72 while (supported_mechs[i]->name != NULL) {
73 if (GSS_ERROR(gss_test_oid_set_member(&min_status,
74 &supported_mechs[i]->oid, supported, &present)))
75 present = 0;
76 if (present)
77 gss_add_oid_set_member(&min_status,
78 &supported_mechs[i]->oid, oidset);
79 i++;
80 }
81}
82
83
84/* Wrapper around accept_sec_context
85 * Requires that the context contains:
86 * oid
87 * credentials (from ssh_gssapi_acquire_cred)
88 */
89/* Privileged */
90OM_uint32
91ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok,
92 gss_buffer_desc *send_tok, OM_uint32 *flags)
93{
94 OM_uint32 status;
95 gss_OID mech;
96
97 ctx->major = gss_accept_sec_context(&ctx->minor,
98 &ctx->context, ctx->creds, recv_tok,
99 GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech,
100 send_tok, flags, NULL, &ctx->client_creds);
101
102 if (GSS_ERROR(ctx->major))
103 ssh_gssapi_error(ctx);
104
105 if (ctx->client_creds)
106 debug("Received some client credentials");
107 else
108 debug("Got no client credentials");
109
110 status = ctx->major;
111
112 /* Now, if we're complete and we have the right flags, then
113 * we flag the user as also having been authenticated
114 */
115
116 if (((flags == NULL) || ((*flags & GSS_C_MUTUAL_FLAG) &&
117 (*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) {
118 if (ssh_gssapi_getclient(ctx, &gssapi_client))
119 fatal("Couldn't convert client name");
120 }
121
122 return (status);
123}
124
125/*
126 * This parses an exported name, extracting the mechanism specific portion
127 * to use for ACL checking. It verifies that the name belongs the mechanism
128 * originally selected.
129 */
130static OM_uint32
131ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name)
132{
133 u_char *tok;
134 OM_uint32 offset;
135 OM_uint32 oidl;
136
137 tok = ename->value;
138
139 /*
140 * Check that ename is long enough for all of the fixed length
141 * header, and that the initial ID bytes are correct
142 */
143
144 if (ename->length < 6 || memcmp(tok, "\x04\x01", 2) != 0)
145 return GSS_S_FAILURE;
146
147 /*
148 * Extract the OID, and check it. Here GSSAPI breaks with tradition
149 * and does use the OID type and length bytes. To confuse things
150 * there are two lengths - the first including these, and the
151 * second without.
152 */
153
154 oidl = GET_16BIT(tok+2); /* length including next two bytes */
155 oidl = oidl-2; /* turn it into the _real_ length of the variable OID */
156
157 /*
158 * Check the BER encoding for correct type and length, that the
159 * string is long enough and that the OID matches that in our context
160 */
161 if (tok[4] != 0x06 || tok[5] != oidl ||
162 ename->length < oidl+6 ||
163 !ssh_gssapi_check_oid(ctx, tok+6, oidl))
164 return GSS_S_FAILURE;
165
166 offset = oidl+6;
167
168 if (ename->length < offset+4)
169 return GSS_S_FAILURE;
170
171 name->length = GET_32BIT(tok+offset);
172 offset += 4;
173
174 if (ename->length < offset+name->length)
175 return GSS_S_FAILURE;
176
177 name->value = xmalloc(name->length+1);
178 memcpy(name->value, tok+offset,name->length);
179 ((char *)name->value)[name->length] = 0;
180
181 return GSS_S_COMPLETE;
182}
183
184/* Extract the client details from a given context. This can only reliably
185 * be called once for a context */
186
187/* Privileged (called from accept_secure_ctx) */
188OM_uint32
189ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client)
190{
191 int i = 0;
192
193 gss_buffer_desc ename;
194
195 client->mech = NULL;
196
197 while (supported_mechs[i]->name != NULL) {
198 if (supported_mechs[i]->oid.length == ctx->oid->length &&
199 (memcmp(supported_mechs[i]->oid.elements,
200 ctx->oid->elements, ctx->oid->length) == 0))
201 client->mech = supported_mechs[i];
202 i++;
203 }
204
205 if (client->mech == NULL)
206 return GSS_S_FAILURE;
207
208 if ((ctx->major = gss_display_name(&ctx->minor, ctx->client,
209 &client->displayname, NULL))) {
210 ssh_gssapi_error(ctx);
211 return (ctx->major);
212 }
213
214 if ((ctx->major = gss_export_name(&ctx->minor, ctx->client,
215 &ename))) {
216 ssh_gssapi_error(ctx);
217 return (ctx->major);
218 }
219
220 if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename,
221 &client->exportedname))) {
222 return (ctx->major);
223 }
224
225 /* We can't copy this structure, so we just move the pointer to it */
226 client->creds = ctx->client_creds;
227 ctx->client_creds = GSS_C_NO_CREDENTIAL;
228 return (ctx->major);
229}
230
231/* As user - called on fatal/exit */
232void
233ssh_gssapi_cleanup_creds(void)
234{
235 if (gssapi_client.store.filename != NULL) {
236 /* Unlink probably isn't sufficient */
237 debug("removing gssapi cred file\"%s\"", gssapi_client.store.filename);
238 unlink(gssapi_client.store.filename);
239 }
240}
241
242/* As user */
243void
244ssh_gssapi_storecreds(void)
245{
246 if (gssapi_client.mech && gssapi_client.mech->storecreds) {
247 (*gssapi_client.mech->storecreds)(&gssapi_client);
248 } else
249 debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism");
250}
251
252/* This allows GSSAPI methods to do things to the childs environment based
253 * on the passed authentication process and credentials.
254 */
255/* As user */
256void
257ssh_gssapi_do_child(char ***envp, u_int *envsizep)
258{
259
260 if (gssapi_client.store.envvar != NULL &&
261 gssapi_client.store.envval != NULL) {
262 debug("Setting %s to %s", gssapi_client.store.envvar,
263 gssapi_client.store.envval);
264 child_set_env(envp, envsizep, gssapi_client.store.envvar,
265 gssapi_client.store.envval);
266 }
267}
268
269/* Privileged */
270int
271ssh_gssapi_userok(char *user)
272{
273 OM_uint32 lmin;
274
275 if (gssapi_client.exportedname.length == 0 ||
276 gssapi_client.exportedname.value == NULL) {
277 debug("No suitable client data");
278 return 0;
279 }
280 if (gssapi_client.mech && gssapi_client.mech->userok)
281 if ((*gssapi_client.mech->userok)(&gssapi_client, user))
282 return 1;
283 else {
284 /* Destroy delegated credentials if userok fails */
285 gss_release_buffer(&lmin, &gssapi_client.displayname);
286 gss_release_buffer(&lmin, &gssapi_client.exportedname);
287 gss_release_cred(&lmin, &gssapi_client.creds);
288 memset(&gssapi_client, 0, sizeof(ssh_gssapi_client));
289 return 0;
290 }
291 else
292 debug("ssh_gssapi_userok: Unknown GSSAPI mechanism");
293 return (0);
294}
295
296/* Privileged */
297OM_uint32
298ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
299{
300 ctx->major = gss_verify_mic(&ctx->minor, ctx->context,
301 gssbuf, gssmic, NULL);
302
303 return (ctx->major);
304}
305
306#endif
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 "auth.h"
33#include "log.h"
34#include "channels.h"
35#include "session.h"
36#include "servconf.h"
37#include "xmalloc.h"
38#include "getput.h"
39
40#include "ssh-gss.h"
41
42static ssh_gssapi_client gssapi_client =
43 { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER,
44 GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}};
45
46ssh_gssapi_mech gssapi_null_mech =
47 { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL};
48
49#ifdef KRB5
50extern ssh_gssapi_mech gssapi_kerberos_mech;
51#endif
52
53ssh_gssapi_mech* supported_mechs[]= {
54#ifdef KRB5
55 &gssapi_kerberos_mech,
56#endif
57 &gssapi_null_mech,
58};
59
60/* Unprivileged */
61void
62ssh_gssapi_supported_oids(gss_OID_set *oidset)
63{
64 int i = 0;
65 OM_uint32 min_status;
66 int present;
67 gss_OID_set supported;
68
69 gss_create_empty_oid_set(&min_status, oidset);
70 gss_indicate_mechs(&min_status, &supported);
71
72 while (supported_mechs[i]->name != NULL) {
73 if (GSS_ERROR(gss_test_oid_set_member(&min_status,
74 &supported_mechs[i]->oid, supported, &present)))
75 present = 0;
76 if (present)
77 gss_add_oid_set_member(&min_status,
78 &supported_mechs[i]->oid, oidset);
79 i++;
80 }
81}
82
83
84/* Wrapper around accept_sec_context
85 * Requires that the context contains:
86 * oid
87 * credentials (from ssh_gssapi_acquire_cred)
88 */
89/* Privileged */
90OM_uint32
91ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok,
92 gss_buffer_desc *send_tok, OM_uint32 *flags)
93{
94 OM_uint32 status;
95 gss_OID mech;
96
97 ctx->major = gss_accept_sec_context(&ctx->minor,
98 &ctx->context, ctx->creds, recv_tok,
99 GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech,
100 send_tok, flags, NULL, &ctx->client_creds);
101
102 if (GSS_ERROR(ctx->major))
103 ssh_gssapi_error(ctx);
104
105 if (ctx->client_creds)
106 debug("Received some client credentials");
107 else
108 debug("Got no client credentials");
109
110 status = ctx->major;
111
112 /* Now, if we're complete and we have the right flags, then
113 * we flag the user as also having been authenticated
114 */
115
116 if (((flags == NULL) || ((*flags & GSS_C_MUTUAL_FLAG) &&
117 (*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) {
118 if (ssh_gssapi_getclient(ctx, &gssapi_client))
119 fatal("Couldn't convert client name");
120 }
121
122 return (status);
123}
124
125/*
126 * This parses an exported name, extracting the mechanism specific portion
127 * to use for ACL checking. It verifies that the name belongs the mechanism
128 * originally selected.
129 */
130static OM_uint32
131ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name)
132{
133 u_char *tok;
134 OM_uint32 offset;
135 OM_uint32 oidl;
136
137 tok = ename->value;
138
139 /*
140 * Check that ename is long enough for all of the fixed length
141 * header, and that the initial ID bytes are correct
142 */
143
144 if (ename->length < 6 || memcmp(tok, "\x04\x01", 2) != 0)
145 return GSS_S_FAILURE;
146
147 /*
148 * Extract the OID, and check it. Here GSSAPI breaks with tradition
149 * and does use the OID type and length bytes. To confuse things
150 * there are two lengths - the first including these, and the
151 * second without.
152 */
153
154 oidl = GET_16BIT(tok+2); /* length including next two bytes */
155 oidl = oidl-2; /* turn it into the _real_ length of the variable OID */
156
157 /*
158 * Check the BER encoding for correct type and length, that the
159 * string is long enough and that the OID matches that in our context
160 */
161 if (tok[4] != 0x06 || tok[5] != oidl ||
162 ename->length < oidl+6 ||
163 !ssh_gssapi_check_oid(ctx, tok+6, oidl))
164 return GSS_S_FAILURE;
165
166 offset = oidl+6;
167
168 if (ename->length < offset+4)
169 return GSS_S_FAILURE;
170
171 name->length = GET_32BIT(tok+offset);
172 offset += 4;
173
174 if (ename->length < offset+name->length)
175 return GSS_S_FAILURE;
176
177 name->value = xmalloc(name->length+1);
178 memcpy(name->value, tok+offset,name->length);
179 ((char *)name->value)[name->length] = 0;
180
181 return GSS_S_COMPLETE;
182}
183
184/* Extract the client details from a given context. This can only reliably
185 * be called once for a context */
186
187/* Privileged (called from accept_secure_ctx) */
188OM_uint32
189ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client)
190{
191 int i = 0;
192
193 gss_buffer_desc ename;
194
195 client->mech = NULL;
196
197 while (supported_mechs[i]->name != NULL) {
198 if (supported_mechs[i]->oid.length == ctx->oid->length &&
199 (memcmp(supported_mechs[i]->oid.elements,
200 ctx->oid->elements, ctx->oid->length) == 0))
201 client->mech = supported_mechs[i];
202 i++;
203 }
204
205 if (client->mech == NULL)
206 return GSS_S_FAILURE;
207
208 if ((ctx->major = gss_display_name(&ctx->minor, ctx->client,
209 &client->displayname, NULL))) {
210 ssh_gssapi_error(ctx);
211 return (ctx->major);
212 }
213
214 if ((ctx->major = gss_export_name(&ctx->minor, ctx->client,
215 &ename))) {
216 ssh_gssapi_error(ctx);
217 return (ctx->major);
218 }
219
220 if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename,
221 &client->exportedname))) {
222 return (ctx->major);
223 }
224
225 /* We can't copy this structure, so we just move the pointer to it */
226 client->creds = ctx->client_creds;
227 ctx->client_creds = GSS_C_NO_CREDENTIAL;
228 return (ctx->major);
229}
230
231/* As user - called on fatal/exit */
232void
233ssh_gssapi_cleanup_creds(void)
234{
235 if (gssapi_client.store.filename != NULL) {
236 /* Unlink probably isn't sufficient */
237 debug("removing gssapi cred file\"%s\"", gssapi_client.store.filename);
238 unlink(gssapi_client.store.filename);
239 }
240}
241
242/* As user */
243void
244ssh_gssapi_storecreds(void)
245{
246 if (gssapi_client.mech && gssapi_client.mech->storecreds) {
247 (*gssapi_client.mech->storecreds)(&gssapi_client);
248 } else
249 debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism");
250}
251
252/* This allows GSSAPI methods to do things to the childs environment based
253 * on the passed authentication process and credentials.
254 */
255/* As user */
256void
257ssh_gssapi_do_child(char ***envp, u_int *envsizep)
258{
259
260 if (gssapi_client.store.envvar != NULL &&
261 gssapi_client.store.envval != NULL) {
262 debug("Setting %s to %s", gssapi_client.store.envvar,
263 gssapi_client.store.envval);
264 child_set_env(envp, envsizep, gssapi_client.store.envvar,
265 gssapi_client.store.envval);
266 }
267}
268
269/* Privileged */
270int
271ssh_gssapi_userok(char *user)
272{
273 OM_uint32 lmin;
274
275 if (gssapi_client.exportedname.length == 0 ||
276 gssapi_client.exportedname.value == NULL) {
277 debug("No suitable client data");
278 return 0;
279 }
280 if (gssapi_client.mech && gssapi_client.mech->userok)
281 if ((*gssapi_client.mech->userok)(&gssapi_client, user))
282 return 1;
283 else {
284 /* Destroy delegated credentials if userok fails */
285 gss_release_buffer(&lmin, &gssapi_client.displayname);
286 gss_release_buffer(&lmin, &gssapi_client.exportedname);
287 gss_release_cred(&lmin, &gssapi_client.creds);
288 memset(&gssapi_client, 0, sizeof(ssh_gssapi_client));
289 return 0;
290 }
291 else
292 debug("ssh_gssapi_userok: Unknown GSSAPI mechanism");
293 return (0);
294}
295
296/* Privileged */
297OM_uint32
298ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
299{
300 ctx->major = gss_verify_mic(&ctx->minor, ctx->context,
301 gssbuf, gssmic, NULL);
302
303 return (ctx->major);
304}
305
306#endif