1 /* $OpenBSD: ssh-pkcs11-helper.c,v 1.3 2010/02/24 06:12:53 djm Exp $ */
2 /*
3 * Copyright (c) 2010 Markus Friedl. All rights reserved.
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18 #include "includes.h"
19
20 #include <sys/types.h>
21 #ifdef HAVE_SYS_TIME_H
22 # include <sys/time.h>
23 #endif
24
25 #include "openbsd-compat/sys-queue.h"
26
27 #include <stdarg.h>
28 #include <string.h>
29 #include <unistd.h>
30 #include <errno.h>
31
32 #include "xmalloc.h"
33 #include "buffer.h"
34 #include "log.h"
35 #include "misc.h"
36 #include "key.h"
37 #include "authfd.h"
38 #include "ssh-pkcs11.h"
39
40 #ifdef ENABLE_PKCS11
41
42 /* borrows code from sftp-server and ssh-agent */
43
44 struct pkcs11_keyinfo {
45 Key *key;
46 char *providername;
47 TAILQ_ENTRY(pkcs11_keyinfo) next;
48 };
49
50 TAILQ_HEAD(, pkcs11_keyinfo) pkcs11_keylist;
51
52 #define MAX_MSG_LENGTH 10240 /*XXX*/
53
54 /* helper */
55 #define get_int() buffer_get_int(&iqueue);
56 #define get_string(lenp) buffer_get_string(&iqueue, lenp);
57
58 /* input and output queue */
59 Buffer iqueue;
60 Buffer oqueue;
61
62 static void
add_key(Key * k,char * name)63 add_key(Key *k, char *name)
64 {
65 struct pkcs11_keyinfo *ki;
66
67 ki = xcalloc(1, sizeof(*ki));
68 ki->providername = xstrdup(name);
69 ki->key = k;
70 TAILQ_INSERT_TAIL(&pkcs11_keylist, ki, next);
71 }
72
73 static void
del_keys_by_name(char * name)74 del_keys_by_name(char *name)
75 {
76 struct pkcs11_keyinfo *ki, *nxt;
77
78 for (ki = TAILQ_FIRST(&pkcs11_keylist); ki; ki = nxt) {
79 nxt = TAILQ_NEXT(ki, next);
80 if (!strcmp(ki->providername, name)) {
81 TAILQ_REMOVE(&pkcs11_keylist, ki, next);
82 xfree(ki->providername);
83 key_free(ki->key);
84 free(ki);
85 }
86 }
87 }
88
89 /* lookup matching 'private' key */
90 static Key *
lookup_key(Key * k)91 lookup_key(Key *k)
92 {
93 struct pkcs11_keyinfo *ki;
94
95 TAILQ_FOREACH(ki, &pkcs11_keylist, next) {
96 debug("check %p %s", ki, ki->providername);
97 if (key_equal(k, ki->key))
98 return (ki->key);
99 }
100 return (NULL);
101 }
102
103 static void
send_msg(Buffer * m)104 send_msg(Buffer *m)
105 {
106 int mlen = buffer_len(m);
107
108 buffer_put_int(&oqueue, mlen);
109 buffer_append(&oqueue, buffer_ptr(m), mlen);
110 buffer_consume(m, mlen);
111 }
112
113 static void
process_add(void)114 process_add(void)
115 {
116 char *name, *pin;
117 Key **keys;
118 int i, nkeys;
119 u_char *blob;
120 u_int blen;
121 Buffer msg;
122
123 buffer_init(&msg);
124 name = get_string(NULL);
125 pin = get_string(NULL);
126 if ((nkeys = pkcs11_add_provider(name, pin, &keys)) > 0) {
127 buffer_put_char(&msg, SSH2_AGENT_IDENTITIES_ANSWER);
128 buffer_put_int(&msg, nkeys);
129 for (i = 0; i < nkeys; i++) {
130 key_to_blob(keys[i], &blob, &blen);
131 buffer_put_string(&msg, blob, blen);
132 buffer_put_cstring(&msg, name);
133 xfree(blob);
134 add_key(keys[i], name);
135 }
136 xfree(keys);
137 } else {
138 buffer_put_char(&msg, SSH_AGENT_FAILURE);
139 }
140 xfree(pin);
141 xfree(name);
142 send_msg(&msg);
143 buffer_free(&msg);
144 }
145
146 static void
process_del(void)147 process_del(void)
148 {
149 char *name, *pin;
150 Buffer msg;
151
152 buffer_init(&msg);
153 name = get_string(NULL);
154 pin = get_string(NULL);
155 del_keys_by_name(name);
156 if (pkcs11_del_provider(name) == 0)
157 buffer_put_char(&msg, SSH_AGENT_SUCCESS);
158 else
159 buffer_put_char(&msg, SSH_AGENT_FAILURE);
160 xfree(pin);
161 xfree(name);
162 send_msg(&msg);
163 buffer_free(&msg);
164 }
165
166 static void
process_sign(void)167 process_sign(void)
168 {
169 u_char *blob, *data, *signature = NULL;
170 u_int blen, dlen, slen = 0;
171 int ok = -1, flags, ret;
172 Key *key, *found;
173 Buffer msg;
174
175 blob = get_string(&blen);
176 data = get_string(&dlen);
177 flags = get_int(); /* XXX ignore */
178
179 if ((key = key_from_blob(blob, blen)) != NULL) {
180 if ((found = lookup_key(key)) != NULL) {
181 slen = RSA_size(key->rsa);
182 signature = xmalloc(slen);
183 if ((ret = RSA_private_encrypt(dlen, data, signature,
184 found->rsa, RSA_PKCS1_PADDING)) != -1) {
185 slen = ret;
186 ok = 0;
187 }
188 }
189 key_free(key);
190 }
191 buffer_init(&msg);
192 if (ok == 0) {
193 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
194 buffer_put_string(&msg, signature, slen);
195 } else {
196 buffer_put_char(&msg, SSH_AGENT_FAILURE);
197 }
198 xfree(data);
199 xfree(blob);
200 if (signature != NULL)
201 xfree(signature);
202 send_msg(&msg);
203 buffer_free(&msg);
204 }
205
206 static void
process(void)207 process(void)
208 {
209 u_int msg_len;
210 u_int buf_len;
211 u_int consumed;
212 u_int type;
213 u_char *cp;
214
215 buf_len = buffer_len(&iqueue);
216 if (buf_len < 5)
217 return; /* Incomplete message. */
218 cp = buffer_ptr(&iqueue);
219 msg_len = get_u32(cp);
220 if (msg_len > MAX_MSG_LENGTH) {
221 error("bad message len %d", msg_len);
222 cleanup_exit(11);
223 }
224 if (buf_len < msg_len + 4)
225 return;
226 buffer_consume(&iqueue, 4);
227 buf_len -= 4;
228 type = buffer_get_char(&iqueue);
229 switch (type) {
230 case SSH_AGENTC_ADD_SMARTCARD_KEY:
231 debug("process_add");
232 process_add();
233 break;
234 case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
235 debug("process_del");
236 process_del();
237 break;
238 case SSH2_AGENTC_SIGN_REQUEST:
239 debug("process_sign");
240 process_sign();
241 break;
242 default:
243 error("Unknown message %d", type);
244 break;
245 }
246 /* discard the remaining bytes from the current packet */
247 if (buf_len < buffer_len(&iqueue)) {
248 error("iqueue grew unexpectedly");
249 cleanup_exit(255);
250 }
251 consumed = buf_len - buffer_len(&iqueue);
252 if (msg_len < consumed) {
253 error("msg_len %d < consumed %d", msg_len, consumed);
254 cleanup_exit(255);
255 }
256 if (msg_len > consumed)
257 buffer_consume(&iqueue, msg_len - consumed);
258 }
259
260 void
cleanup_exit(int i)261 cleanup_exit(int i)
262 {
263 /* XXX */
264 _exit(i);
265 }
266
267 int
main(int argc,char ** argv)268 main(int argc, char **argv)
269 {
270 fd_set *rset, *wset;
271 int in, out, max, log_stderr = 0;
272 ssize_t len, olen, set_size;
273 SyslogFacility log_facility = SYSLOG_FACILITY_AUTH;
274 LogLevel log_level = SYSLOG_LEVEL_ERROR;
275 char buf[4*4096];
276
277 extern char *optarg;
278 extern char *__progname;
279
280 TAILQ_INIT(&pkcs11_keylist);
281 pkcs11_init(0);
282
283 seed_rng();
284 __progname = ssh_get_progname(argv[0]);
285
286 log_init(__progname, log_level, log_facility, log_stderr);
287
288 in = STDIN_FILENO;
289 out = STDOUT_FILENO;
290
291 max = 0;
292 if (in > max)
293 max = in;
294 if (out > max)
295 max = out;
296
297 buffer_init(&iqueue);
298 buffer_init(&oqueue);
299
300 set_size = howmany(max + 1, NFDBITS) * sizeof(fd_mask);
301 rset = (fd_set *)xmalloc(set_size);
302 wset = (fd_set *)xmalloc(set_size);
303
304 for (;;) {
305 memset(rset, 0, set_size);
306 memset(wset, 0, set_size);
307
308 /*
309 * Ensure that we can read a full buffer and handle
310 * the worst-case length packet it can generate,
311 * otherwise apply backpressure by stopping reads.
312 */
313 if (buffer_check_alloc(&iqueue, sizeof(buf)) &&
314 buffer_check_alloc(&oqueue, MAX_MSG_LENGTH))
315 FD_SET(in, rset);
316
317 olen = buffer_len(&oqueue);
318 if (olen > 0)
319 FD_SET(out, wset);
320
321 if (select(max+1, rset, wset, NULL, NULL) < 0) {
322 if (errno == EINTR)
323 continue;
324 error("select: %s", strerror(errno));
325 cleanup_exit(2);
326 }
327
328 /* copy stdin to iqueue */
329 if (FD_ISSET(in, rset)) {
330 len = read(in, buf, sizeof buf);
331 if (len == 0) {
332 debug("read eof");
333 cleanup_exit(0);
334 } else if (len < 0) {
335 error("read: %s", strerror(errno));
336 cleanup_exit(1);
337 } else {
338 buffer_append(&iqueue, buf, len);
339 }
340 }
341 /* send oqueue to stdout */
342 if (FD_ISSET(out, wset)) {
343 len = write(out, buffer_ptr(&oqueue), olen);
344 if (len < 0) {
345 error("write: %s", strerror(errno));
346 cleanup_exit(1);
347 } else {
348 buffer_consume(&oqueue, len);
349 }
350 }
351
352 /*
353 * Process requests from client if we can fit the results
354 * into the output buffer, otherwise stop processing input
355 * and let the output queue drain.
356 */
357 if (buffer_check_alloc(&oqueue, MAX_MSG_LENGTH))
358 process();
359 }
360 }
361 #else /* ENABLE_PKCS11 */
362 int
main(int argc,char ** argv)363 main(int argc, char **argv)
364 {
365 extern char *__progname;
366
367 __progname = ssh_get_progname(argv[0]);
368 log_init(__progname, SYSLOG_LEVEL_ERROR, SYSLOG_FACILITY_AUTH, 0);
369 fatal("PKCS#11 support disabled at compile time");
370 }
371 #endif /* ENABLE_PKCS11 */
372