1 /* $OpenBSD: ssh-pkcs11-helper.c,v 1.24 2020/10/18 11:32:02 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 <sys/types.h> 19 #include <sys/queue.h> 20 #include <sys/time.h> 21 22 #include <stdlib.h> 23 #include <errno.h> 24 #include <poll.h> 25 #include <stdarg.h> 26 #include <string.h> 27 #include <unistd.h> 28 29 #include "xmalloc.h" 30 #include "sshbuf.h" 31 #include "log.h" 32 #include "misc.h" 33 #include "sshkey.h" 34 #include "authfd.h" 35 #include "ssh-pkcs11.h" 36 #include "ssherr.h" 37 38 #ifdef WITH_OPENSSL 39 40 /* borrows code from sftp-server and ssh-agent */ 41 42 struct pkcs11_keyinfo { 43 struct sshkey *key; 44 char *providername, *label; 45 TAILQ_ENTRY(pkcs11_keyinfo) next; 46 }; 47 48 TAILQ_HEAD(, pkcs11_keyinfo) pkcs11_keylist; 49 50 #define MAX_MSG_LENGTH 10240 /*XXX*/ 51 52 /* input and output queue */ 53 struct sshbuf *iqueue; 54 struct sshbuf *oqueue; 55 56 static void 57 add_key(struct sshkey *k, char *name, char *label) 58 { 59 struct pkcs11_keyinfo *ki; 60 61 ki = xcalloc(1, sizeof(*ki)); 62 ki->providername = xstrdup(name); 63 ki->key = k; 64 ki->label = xstrdup(label); 65 TAILQ_INSERT_TAIL(&pkcs11_keylist, ki, next); 66 } 67 68 static void 69 del_keys_by_name(char *name) 70 { 71 struct pkcs11_keyinfo *ki, *nxt; 72 73 for (ki = TAILQ_FIRST(&pkcs11_keylist); ki; ki = nxt) { 74 nxt = TAILQ_NEXT(ki, next); 75 if (!strcmp(ki->providername, name)) { 76 TAILQ_REMOVE(&pkcs11_keylist, ki, next); 77 free(ki->providername); 78 free(ki->label); 79 sshkey_free(ki->key); 80 free(ki); 81 } 82 } 83 } 84 85 /* lookup matching 'private' key */ 86 static struct sshkey * 87 lookup_key(struct sshkey *k) 88 { 89 struct pkcs11_keyinfo *ki; 90 91 TAILQ_FOREACH(ki, &pkcs11_keylist, next) { 92 debug("check %p %s %s", ki, ki->providername, ki->label); 93 if (sshkey_equal(k, ki->key)) 94 return (ki->key); 95 } 96 return (NULL); 97 } 98 99 static void 100 send_msg(struct sshbuf *m) 101 { 102 int r; 103 104 if ((r = sshbuf_put_stringb(oqueue, m)) != 0) 105 fatal_fr(r, "enqueue"); 106 } 107 108 static void 109 process_add(void) 110 { 111 char *name, *pin; 112 struct sshkey **keys = NULL; 113 int r, i, nkeys; 114 u_char *blob; 115 size_t blen; 116 struct sshbuf *msg; 117 char **labels = NULL; 118 119 if ((msg = sshbuf_new()) == NULL) 120 fatal_f("sshbuf_new failed"); 121 if ((r = sshbuf_get_cstring(iqueue, &name, NULL)) != 0 || 122 (r = sshbuf_get_cstring(iqueue, &pin, NULL)) != 0) 123 fatal_fr(r, "parse"); 124 if ((nkeys = pkcs11_add_provider(name, pin, &keys, &labels)) > 0) { 125 if ((r = sshbuf_put_u8(msg, 126 SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 127 (r = sshbuf_put_u32(msg, nkeys)) != 0) 128 fatal_fr(r, "compose"); 129 for (i = 0; i < nkeys; i++) { 130 if ((r = sshkey_to_blob(keys[i], &blob, &blen)) != 0) { 131 debug_fr(r, "encode key"); 132 continue; 133 } 134 if ((r = sshbuf_put_string(msg, blob, blen)) != 0 || 135 (r = sshbuf_put_cstring(msg, labels[i])) != 0) 136 fatal_fr(r, "compose key"); 137 free(blob); 138 add_key(keys[i], name, labels[i]); 139 free(labels[i]); 140 } 141 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0 || 142 (r = sshbuf_put_u32(msg, -nkeys)) != 0) 143 fatal_fr(r, "compose"); 144 free(labels); 145 free(keys); /* keys themselves are transferred to pkcs11_keylist */ 146 free(pin); 147 free(name); 148 send_msg(msg); 149 sshbuf_free(msg); 150 } 151 152 static void 153 process_del(void) 154 { 155 char *name, *pin; 156 struct sshbuf *msg; 157 int r; 158 159 if ((msg = sshbuf_new()) == NULL) 160 fatal_f("sshbuf_new failed"); 161 if ((r = sshbuf_get_cstring(iqueue, &name, NULL)) != 0 || 162 (r = sshbuf_get_cstring(iqueue, &pin, NULL)) != 0) 163 fatal_fr(r, "parse"); 164 del_keys_by_name(name); 165 if ((r = sshbuf_put_u8(msg, pkcs11_del_provider(name) == 0 ? 166 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 167 fatal_fr(r, "compose"); 168 free(pin); 169 free(name); 170 send_msg(msg); 171 sshbuf_free(msg); 172 } 173 174 static void 175 process_sign(void) 176 { 177 u_char *blob, *data, *signature = NULL; 178 size_t blen, dlen, slen = 0; 179 int r, ok = -1; 180 struct sshkey *key, *found; 181 struct sshbuf *msg; 182 183 /* XXX support SHA2 signature flags */ 184 if ((r = sshbuf_get_string(iqueue, &blob, &blen)) != 0 || 185 (r = sshbuf_get_string(iqueue, &data, &dlen)) != 0 || 186 (r = sshbuf_get_u32(iqueue, NULL)) != 0) 187 fatal_fr(r, "parse"); 188 189 if ((r = sshkey_from_blob(blob, blen, &key)) != 0) 190 fatal_fr(r, "decode key"); 191 else { 192 if ((found = lookup_key(key)) != NULL) { 193 #ifdef WITH_OPENSSL 194 int ret; 195 196 if (key->type == KEY_RSA) { 197 slen = RSA_size(key->rsa); 198 signature = xmalloc(slen); 199 ret = RSA_private_encrypt(dlen, data, signature, 200 found->rsa, RSA_PKCS1_PADDING); 201 if (ret != -1) { 202 slen = ret; 203 ok = 0; 204 } 205 } else if (key->type == KEY_ECDSA) { 206 u_int xslen = ECDSA_size(key->ecdsa); 207 208 signature = xmalloc(xslen); 209 /* "The parameter type is ignored." */ 210 ret = ECDSA_sign(-1, data, dlen, signature, 211 &xslen, found->ecdsa); 212 if (ret != 0) 213 ok = 0; 214 else 215 error_f("ECDSA_sign returned %d", ret); 216 slen = xslen; 217 } else 218 error_f("don't know how to sign with key " 219 "type %d", (int)key->type); 220 #endif /* WITH_OPENSSL */ 221 } 222 sshkey_free(key); 223 } 224 if ((msg = sshbuf_new()) == NULL) 225 fatal_f("sshbuf_new failed"); 226 if (ok == 0) { 227 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 228 (r = sshbuf_put_string(msg, signature, slen)) != 0) 229 fatal_fr(r, "compose response"); 230 } else { 231 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_FAILURE)) != 0) 232 fatal_fr(r, "compose failure response"); 233 } 234 free(data); 235 free(blob); 236 free(signature); 237 send_msg(msg); 238 sshbuf_free(msg); 239 } 240 241 static void 242 process(void) 243 { 244 u_int msg_len; 245 u_int buf_len; 246 u_int consumed; 247 u_char type; 248 const u_char *cp; 249 int r; 250 251 buf_len = sshbuf_len(iqueue); 252 if (buf_len < 5) 253 return; /* Incomplete message. */ 254 cp = sshbuf_ptr(iqueue); 255 msg_len = get_u32(cp); 256 if (msg_len > MAX_MSG_LENGTH) { 257 error("bad message len %d", msg_len); 258 cleanup_exit(11); 259 } 260 if (buf_len < msg_len + 4) 261 return; 262 if ((r = sshbuf_consume(iqueue, 4)) != 0 || 263 (r = sshbuf_get_u8(iqueue, &type)) != 0) 264 fatal_fr(r, "parse type/len"); 265 buf_len -= 4; 266 switch (type) { 267 case SSH_AGENTC_ADD_SMARTCARD_KEY: 268 debug("process_add"); 269 process_add(); 270 break; 271 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 272 debug("process_del"); 273 process_del(); 274 break; 275 case SSH2_AGENTC_SIGN_REQUEST: 276 debug("process_sign"); 277 process_sign(); 278 break; 279 default: 280 error("Unknown message %d", type); 281 break; 282 } 283 /* discard the remaining bytes from the current packet */ 284 if (buf_len < sshbuf_len(iqueue)) { 285 error("iqueue grew unexpectedly"); 286 cleanup_exit(255); 287 } 288 consumed = buf_len - sshbuf_len(iqueue); 289 if (msg_len < consumed) { 290 error("msg_len %d < consumed %d", msg_len, consumed); 291 cleanup_exit(255); 292 } 293 if (msg_len > consumed) { 294 if ((r = sshbuf_consume(iqueue, msg_len - consumed)) != 0) 295 fatal_fr(r, "consume"); 296 } 297 } 298 299 void 300 cleanup_exit(int i) 301 { 302 /* XXX */ 303 _exit(i); 304 } 305 306 307 int 308 main(int argc, char **argv) 309 { 310 int r, ch, in, out, log_stderr = 0; 311 ssize_t len; 312 SyslogFacility log_facility = SYSLOG_FACILITY_AUTH; 313 LogLevel log_level = SYSLOG_LEVEL_ERROR; 314 char buf[4*4096]; 315 extern char *__progname; 316 struct pollfd pfd[2]; 317 318 TAILQ_INIT(&pkcs11_keylist); 319 320 log_init(__progname, log_level, log_facility, log_stderr); 321 322 while ((ch = getopt(argc, argv, "v")) != -1) { 323 switch (ch) { 324 case 'v': 325 log_stderr = 1; 326 if (log_level == SYSLOG_LEVEL_ERROR) 327 log_level = SYSLOG_LEVEL_DEBUG1; 328 else if (log_level < SYSLOG_LEVEL_DEBUG3) 329 log_level++; 330 break; 331 default: 332 fprintf(stderr, "usage: %s [-v]\n", __progname); 333 exit(1); 334 } 335 } 336 337 log_init(__progname, log_level, log_facility, log_stderr); 338 339 pkcs11_init(0); 340 in = STDIN_FILENO; 341 out = STDOUT_FILENO; 342 343 if ((iqueue = sshbuf_new()) == NULL) 344 fatal_f("sshbuf_new failed"); 345 if ((oqueue = sshbuf_new()) == NULL) 346 fatal_f("sshbuf_new failed"); 347 348 while (1) { 349 memset(pfd, 0, sizeof(pfd)); 350 pfd[0].fd = in; 351 pfd[1].fd = out; 352 353 /* 354 * Ensure that we can read a full buffer and handle 355 * the worst-case length packet it can generate, 356 * otherwise apply backpressure by stopping reads. 357 */ 358 if ((r = sshbuf_check_reserve(iqueue, sizeof(buf))) == 0 && 359 (r = sshbuf_check_reserve(oqueue, MAX_MSG_LENGTH)) == 0) 360 pfd[0].events = POLLIN; 361 else if (r != SSH_ERR_NO_BUFFER_SPACE) 362 fatal_fr(r, "reserve"); 363 364 if (sshbuf_len(oqueue) > 0) 365 pfd[1].events = POLLOUT; 366 367 if ((r = poll(pfd, 2, -1 /* INFTIM */)) <= 0) { 368 if (r == 0 || errno == EINTR) 369 continue; 370 fatal("poll: %s", strerror(errno)); 371 } 372 373 /* copy stdin to iqueue */ 374 if ((pfd[0].revents & (POLLIN|POLLERR)) != 0) { 375 len = read(in, buf, sizeof buf); 376 if (len == 0) { 377 debug("read eof"); 378 cleanup_exit(0); 379 } else if (len < 0) { 380 error("read: %s", strerror(errno)); 381 cleanup_exit(1); 382 } else if ((r = sshbuf_put(iqueue, buf, len)) != 0) 383 fatal_fr(r, "sshbuf_put"); 384 } 385 /* send oqueue to stdout */ 386 if ((pfd[1].revents & (POLLOUT|POLLHUP)) != 0) { 387 len = write(out, sshbuf_ptr(oqueue), 388 sshbuf_len(oqueue)); 389 if (len < 0) { 390 error("write: %s", strerror(errno)); 391 cleanup_exit(1); 392 } else if ((r = sshbuf_consume(oqueue, len)) != 0) 393 fatal_fr(r, "consume"); 394 } 395 396 /* 397 * Process requests from client if we can fit the results 398 * into the output buffer, otherwise stop processing input 399 * and let the output queue drain. 400 */ 401 if ((r = sshbuf_check_reserve(oqueue, MAX_MSG_LENGTH)) == 0) 402 process(); 403 else if (r != SSH_ERR_NO_BUFFER_SPACE) 404 fatal_fr(r, "reserve"); 405 } 406 } 407 408 #else /* WITH_OPENSSL */ 409 void 410 cleanup_exit(int i) 411 { 412 _exit(i); 413 } 414 415 int 416 main(int argc, char **argv) 417 { 418 fprintf(stderr, "PKCS#11 code is not enabled\n"); 419 return 1; 420 } 421 #endif /* WITH_OPENSSL */ 422