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Diffstat (limited to 'kexgsss.c')
-rw-r--r-- | kexgsss.c | 271 |
1 files changed, 271 insertions, 0 deletions
diff --git a/kexgsss.c b/kexgsss.c new file mode 100644 index 000000000..3ca23bbb2 --- /dev/null +++ b/kexgsss.c | |||
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1 | /* | ||
2 | * Copyright (c) 2001-2006 Simon Wilkinson. All rights reserved. | ||
3 | * | ||
4 | * Redistribution and use in source and binary forms, with or without | ||
5 | * modification, are permitted provided that the following conditions | ||
6 | * are met: | ||
7 | * 1. Redistributions of source code must retain the above copyright | ||
8 | * notice, this list of conditions and the following disclaimer. | ||
9 | * 2. Redistributions in binary form must reproduce the above copyright | ||
10 | * notice, this list of conditions and the following disclaimer in the | ||
11 | * documentation and/or other materials provided with the distribution. | ||
12 | * | ||
13 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR | ||
14 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | ||
15 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | ||
16 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | ||
17 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | ||
18 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | ||
19 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | ||
20 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | ||
21 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | ||
22 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | ||
23 | */ | ||
24 | |||
25 | #include "includes.h" | ||
26 | |||
27 | #ifdef GSSAPI | ||
28 | |||
29 | #include <string.h> | ||
30 | |||
31 | #include <openssl/crypto.h> | ||
32 | #include <openssl/bn.h> | ||
33 | |||
34 | #include "xmalloc.h" | ||
35 | #include "buffer.h" | ||
36 | #include "ssh2.h" | ||
37 | #include "key.h" | ||
38 | #include "cipher.h" | ||
39 | #include "kex.h" | ||
40 | #include "log.h" | ||
41 | #include "packet.h" | ||
42 | #include "dh.h" | ||
43 | #include "ssh-gss.h" | ||
44 | #include "monitor_wrap.h" | ||
45 | |||
46 | void | ||
47 | kexgss_server(Kex *kex) | ||
48 | { | ||
49 | OM_uint32 maj_status, min_status; | ||
50 | |||
51 | /* | ||
52 | * Some GSSAPI implementations use the input value of ret_flags (an | ||
53 | * output variable) as a means of triggering mechanism specific | ||
54 | * features. Initializing it to zero avoids inadvertently | ||
55 | * activating this non-standard behaviour. | ||
56 | */ | ||
57 | |||
58 | OM_uint32 ret_flags = 0; | ||
59 | gss_buffer_desc gssbuf, recv_tok, msg_tok; | ||
60 | gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; | ||
61 | Gssctxt *ctxt = NULL; | ||
62 | u_int slen, klen, kout, hashlen; | ||
63 | u_char *kbuf, *hash; | ||
64 | DH *dh; | ||
65 | int min = -1, max = -1, nbits = -1; | ||
66 | BIGNUM *shared_secret = NULL; | ||
67 | BIGNUM *dh_client_pub = NULL; | ||
68 | int type = 0; | ||
69 | gss_OID oid; | ||
70 | |||
71 | /* Initialise GSSAPI */ | ||
72 | |||
73 | /* If we're rekeying, privsep means that some of the private structures | ||
74 | * in the GSSAPI code are no longer available. This kludges them back | ||
75 | * into life | ||
76 | */ | ||
77 | if (!ssh_gssapi_oid_table_ok()) | ||
78 | ssh_gssapi_server_mechanisms(); | ||
79 | |||
80 | debug2("%s: Identifying %s", __func__, kex->name); | ||
81 | oid = ssh_gssapi_id_kex(NULL, kex->name, kex->kex_type); | ||
82 | if (oid == GSS_C_NO_OID) | ||
83 | fatal("Unknown gssapi mechanism"); | ||
84 | |||
85 | debug2("%s: Acquiring credentials", __func__); | ||
86 | |||
87 | if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, oid)))) | ||
88 | fatal("Unable to acquire credentials for the server"); | ||
89 | |||
90 | switch (kex->kex_type) { | ||
91 | case KEX_GSS_GRP1_SHA1: | ||
92 | dh = dh_new_group1(); | ||
93 | break; | ||
94 | case KEX_GSS_GRP14_SHA1: | ||
95 | dh = dh_new_group14(); | ||
96 | break; | ||
97 | case KEX_GSS_GEX_SHA1: | ||
98 | debug("Doing group exchange"); | ||
99 | packet_read_expect(SSH2_MSG_KEXGSS_GROUPREQ); | ||
100 | min = packet_get_int(); | ||
101 | nbits = packet_get_int(); | ||
102 | max = packet_get_int(); | ||
103 | min = MAX(DH_GRP_MIN, min); | ||
104 | max = MIN(DH_GRP_MAX, max); | ||
105 | packet_check_eom(); | ||
106 | if (max < min || nbits < min || max < nbits) | ||
107 | fatal("GSS_GEX, bad parameters: %d !< %d !< %d", | ||
108 | min, nbits, max); | ||
109 | dh = PRIVSEP(choose_dh(min, nbits, max)); | ||
110 | if (dh == NULL) | ||
111 | packet_disconnect("Protocol error: no matching group found"); | ||
112 | |||
113 | packet_start(SSH2_MSG_KEXGSS_GROUP); | ||
114 | packet_put_bignum2(dh->p); | ||
115 | packet_put_bignum2(dh->g); | ||
116 | packet_send(); | ||
117 | |||
118 | packet_write_wait(); | ||
119 | break; | ||
120 | default: | ||
121 | fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type); | ||
122 | } | ||
123 | |||
124 | dh_gen_key(dh, kex->we_need * 8); | ||
125 | |||
126 | do { | ||
127 | debug("Wait SSH2_MSG_GSSAPI_INIT"); | ||
128 | type = packet_read(); | ||
129 | switch(type) { | ||
130 | case SSH2_MSG_KEXGSS_INIT: | ||
131 | if (dh_client_pub != NULL) | ||
132 | fatal("Received KEXGSS_INIT after initialising"); | ||
133 | recv_tok.value = packet_get_string(&slen); | ||
134 | recv_tok.length = slen; | ||
135 | |||
136 | if ((dh_client_pub = BN_new()) == NULL) | ||
137 | fatal("dh_client_pub == NULL"); | ||
138 | |||
139 | packet_get_bignum2(dh_client_pub); | ||
140 | |||
141 | /* Send SSH_MSG_KEXGSS_HOSTKEY here, if we want */ | ||
142 | break; | ||
143 | case SSH2_MSG_KEXGSS_CONTINUE: | ||
144 | recv_tok.value = packet_get_string(&slen); | ||
145 | recv_tok.length = slen; | ||
146 | break; | ||
147 | default: | ||
148 | packet_disconnect( | ||
149 | "Protocol error: didn't expect packet type %d", | ||
150 | type); | ||
151 | } | ||
152 | |||
153 | maj_status = PRIVSEP(ssh_gssapi_accept_ctx(ctxt, &recv_tok, | ||
154 | &send_tok, &ret_flags)); | ||
155 | |||
156 | xfree(recv_tok.value); | ||
157 | |||
158 | if (maj_status != GSS_S_COMPLETE && send_tok.length == 0) | ||
159 | fatal("Zero length token output when incomplete"); | ||
160 | |||
161 | if (dh_client_pub == NULL) | ||
162 | fatal("No client public key"); | ||
163 | |||
164 | if (maj_status & GSS_S_CONTINUE_NEEDED) { | ||
165 | debug("Sending GSSAPI_CONTINUE"); | ||
166 | packet_start(SSH2_MSG_KEXGSS_CONTINUE); | ||
167 | packet_put_string(send_tok.value, send_tok.length); | ||
168 | packet_send(); | ||
169 | gss_release_buffer(&min_status, &send_tok); | ||
170 | } | ||
171 | } while (maj_status & GSS_S_CONTINUE_NEEDED); | ||
172 | |||
173 | if (GSS_ERROR(maj_status)) { | ||
174 | if (send_tok.length > 0) { | ||
175 | packet_start(SSH2_MSG_KEXGSS_CONTINUE); | ||
176 | packet_put_string(send_tok.value, send_tok.length); | ||
177 | packet_send(); | ||
178 | } | ||
179 | fatal("accept_ctx died"); | ||
180 | } | ||
181 | |||
182 | if (!(ret_flags & GSS_C_MUTUAL_FLAG)) | ||
183 | fatal("Mutual Authentication flag wasn't set"); | ||
184 | |||
185 | if (!(ret_flags & GSS_C_INTEG_FLAG)) | ||
186 | fatal("Integrity flag wasn't set"); | ||
187 | |||
188 | if (!dh_pub_is_valid(dh, dh_client_pub)) | ||
189 | packet_disconnect("bad client public DH value"); | ||
190 | |||
191 | klen = DH_size(dh); | ||
192 | kbuf = xmalloc(klen); | ||
193 | kout = DH_compute_key(kbuf, dh_client_pub, dh); | ||
194 | |||
195 | shared_secret = BN_new(); | ||
196 | BN_bin2bn(kbuf, kout, shared_secret); | ||
197 | memset(kbuf, 0, klen); | ||
198 | xfree(kbuf); | ||
199 | |||
200 | switch (kex->kex_type) { | ||
201 | case KEX_GSS_GRP1_SHA1: | ||
202 | case KEX_GSS_GRP14_SHA1: | ||
203 | kex_dh_hash( | ||
204 | kex->client_version_string, kex->server_version_string, | ||
205 | buffer_ptr(&kex->peer), buffer_len(&kex->peer), | ||
206 | buffer_ptr(&kex->my), buffer_len(&kex->my), | ||
207 | NULL, 0, /* Change this if we start sending host keys */ | ||
208 | dh_client_pub, dh->pub_key, shared_secret, | ||
209 | &hash, &hashlen | ||
210 | ); | ||
211 | break; | ||
212 | case KEX_GSS_GEX_SHA1: | ||
213 | kexgex_hash( | ||
214 | kex->evp_md, | ||
215 | kex->client_version_string, kex->server_version_string, | ||
216 | buffer_ptr(&kex->peer), buffer_len(&kex->peer), | ||
217 | buffer_ptr(&kex->my), buffer_len(&kex->my), | ||
218 | NULL, 0, | ||
219 | min, nbits, max, | ||
220 | dh->p, dh->g, | ||
221 | dh_client_pub, | ||
222 | dh->pub_key, | ||
223 | shared_secret, | ||
224 | &hash, &hashlen | ||
225 | ); | ||
226 | break; | ||
227 | default: | ||
228 | fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type); | ||
229 | } | ||
230 | |||
231 | BN_free(dh_client_pub); | ||
232 | |||
233 | if (kex->session_id == NULL) { | ||
234 | kex->session_id_len = hashlen; | ||
235 | kex->session_id = xmalloc(kex->session_id_len); | ||
236 | memcpy(kex->session_id, hash, kex->session_id_len); | ||
237 | } | ||
238 | |||
239 | gssbuf.value = hash; | ||
240 | gssbuf.length = hashlen; | ||
241 | |||
242 | if (GSS_ERROR(PRIVSEP(ssh_gssapi_sign(ctxt,&gssbuf,&msg_tok)))) | ||
243 | fatal("Couldn't get MIC"); | ||
244 | |||
245 | packet_start(SSH2_MSG_KEXGSS_COMPLETE); | ||
246 | packet_put_bignum2(dh->pub_key); | ||
247 | packet_put_string(msg_tok.value,msg_tok.length); | ||
248 | |||
249 | if (send_tok.length != 0) { | ||
250 | packet_put_char(1); /* true */ | ||
251 | packet_put_string(send_tok.value, send_tok.length); | ||
252 | } else { | ||
253 | packet_put_char(0); /* false */ | ||
254 | } | ||
255 | packet_send(); | ||
256 | |||
257 | gss_release_buffer(&min_status, &send_tok); | ||
258 | gss_release_buffer(&min_status, &msg_tok); | ||
259 | |||
260 | if (gss_kex_context == NULL) | ||
261 | gss_kex_context = ctxt; | ||
262 | else | ||
263 | ssh_gssapi_delete_ctx(&ctxt); | ||
264 | |||
265 | DH_free(dh); | ||
266 | |||
267 | kex_derive_keys(kex, hash, hashlen, shared_secret); | ||
268 | BN_clear_free(shared_secret); | ||
269 | kex_finish(kex); | ||
270 | } | ||
271 | #endif /* GSSAPI */ | ||