1 /* $OpenBSD: ssh-pkcs11-helper.c,v 1.26 2021/11/18 03:31:44 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 %s %s %s", sshkey_type(ki->key), 93 ki->providername, ki->label); 94 if (sshkey_equal(k, ki->key)) 95 return (ki->key); 96 } 97 return (NULL); 98 } 99 100 static void 101 send_msg(struct sshbuf *m) 102 { 103 int r; 104 105 if ((r = sshbuf_put_stringb(oqueue, m)) != 0) 106 fatal_fr(r, "enqueue"); 107 } 108 109 static void 110 process_add(void) 111 { 112 char *name, *pin; 113 struct sshkey **keys = NULL; 114 int r, i, nkeys; 115 u_char *blob; 116 size_t blen; 117 struct sshbuf *msg; 118 char **labels = NULL; 119 120 if ((msg = sshbuf_new()) == NULL) 121 fatal_f("sshbuf_new failed"); 122 if ((r = sshbuf_get_cstring(iqueue, &name, NULL)) != 0 || 123 (r = sshbuf_get_cstring(iqueue, &pin, NULL)) != 0) 124 fatal_fr(r, "parse"); 125 if ((nkeys = pkcs11_add_provider(name, pin, &keys, &labels)) > 0) { 126 if ((r = sshbuf_put_u8(msg, 127 SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 128 (r = sshbuf_put_u32(msg, nkeys)) != 0) 129 fatal_fr(r, "compose"); 130 for (i = 0; i < nkeys; i++) { 131 if ((r = sshkey_to_blob(keys[i], &blob, &blen)) != 0) { 132 debug_fr(r, "encode key"); 133 continue; 134 } 135 if ((r = sshbuf_put_string(msg, blob, blen)) != 0 || 136 (r = sshbuf_put_cstring(msg, labels[i])) != 0) 137 fatal_fr(r, "compose key"); 138 free(blob); 139 add_key(keys[i], name, labels[i]); 140 free(labels[i]); 141 } 142 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0 || 143 (r = sshbuf_put_u32(msg, -nkeys)) != 0) 144 fatal_fr(r, "compose"); 145 free(labels); 146 free(keys); /* keys themselves are transferred to pkcs11_keylist */ 147 free(pin); 148 free(name); 149 send_msg(msg); 150 sshbuf_free(msg); 151 } 152 153 static void 154 process_del(void) 155 { 156 char *name, *pin; 157 struct sshbuf *msg; 158 int r; 159 160 if ((msg = sshbuf_new()) == NULL) 161 fatal_f("sshbuf_new failed"); 162 if ((r = sshbuf_get_cstring(iqueue, &name, NULL)) != 0 || 163 (r = sshbuf_get_cstring(iqueue, &pin, NULL)) != 0) 164 fatal_fr(r, "parse"); 165 del_keys_by_name(name); 166 if ((r = sshbuf_put_u8(msg, pkcs11_del_provider(name) == 0 ? 167 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 168 fatal_fr(r, "compose"); 169 free(pin); 170 free(name); 171 send_msg(msg); 172 sshbuf_free(msg); 173 } 174 175 static void 176 process_sign(void) 177 { 178 u_char *blob, *data, *signature = NULL; 179 size_t blen, dlen, slen = 0; 180 int r, ok = -1; 181 struct sshkey *key, *found; 182 struct sshbuf *msg; 183 184 /* XXX support SHA2 signature flags */ 185 if ((r = sshbuf_get_string(iqueue, &blob, &blen)) != 0 || 186 (r = sshbuf_get_string(iqueue, &data, &dlen)) != 0 || 187 (r = sshbuf_get_u32(iqueue, NULL)) != 0) 188 fatal_fr(r, "parse"); 189 190 if ((r = sshkey_from_blob(blob, blen, &key)) != 0) 191 fatal_fr(r, "decode key"); 192 else { 193 if ((found = lookup_key(key)) != NULL) { 194 #ifdef WITH_OPENSSL 195 int ret; 196 197 if (key->type == KEY_RSA) { 198 slen = RSA_size(key->rsa); 199 signature = xmalloc(slen); 200 ret = RSA_private_encrypt(dlen, data, signature, 201 found->rsa, RSA_PKCS1_PADDING); 202 if (ret != -1) { 203 slen = ret; 204 ok = 0; 205 } 206 } else if (key->type == KEY_ECDSA) { 207 u_int xslen = ECDSA_size(key->ecdsa); 208 209 signature = xmalloc(xslen); 210 /* "The parameter type is ignored." */ 211 ret = ECDSA_sign(-1, data, dlen, signature, 212 &xslen, found->ecdsa); 213 if (ret != 0) 214 ok = 0; 215 else 216 error_f("ECDSA_sign returned %d", ret); 217 slen = xslen; 218 } else 219 error_f("don't know how to sign with key " 220 "type %d", (int)key->type); 221 #endif /* WITH_OPENSSL */ 222 } 223 sshkey_free(key); 224 } 225 if ((msg = sshbuf_new()) == NULL) 226 fatal_f("sshbuf_new failed"); 227 if (ok == 0) { 228 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 229 (r = sshbuf_put_string(msg, signature, slen)) != 0) 230 fatal_fr(r, "compose response"); 231 } else { 232 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_FAILURE)) != 0) 233 fatal_fr(r, "compose failure response"); 234 } 235 free(data); 236 free(blob); 237 free(signature); 238 send_msg(msg); 239 sshbuf_free(msg); 240 } 241 242 static void 243 process(void) 244 { 245 u_int msg_len; 246 u_int buf_len; 247 u_int consumed; 248 u_char type; 249 const u_char *cp; 250 int r; 251 252 buf_len = sshbuf_len(iqueue); 253 if (buf_len < 5) 254 return; /* Incomplete message. */ 255 cp = sshbuf_ptr(iqueue); 256 msg_len = get_u32(cp); 257 if (msg_len > MAX_MSG_LENGTH) { 258 error("bad message len %d", msg_len); 259 cleanup_exit(11); 260 } 261 if (buf_len < msg_len + 4) 262 return; 263 if ((r = sshbuf_consume(iqueue, 4)) != 0 || 264 (r = sshbuf_get_u8(iqueue, &type)) != 0) 265 fatal_fr(r, "parse type/len"); 266 buf_len -= 4; 267 switch (type) { 268 case SSH_AGENTC_ADD_SMARTCARD_KEY: 269 debug("process_add"); 270 process_add(); 271 break; 272 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 273 debug("process_del"); 274 process_del(); 275 break; 276 case SSH2_AGENTC_SIGN_REQUEST: 277 debug("process_sign"); 278 process_sign(); 279 break; 280 default: 281 error("Unknown message %d", type); 282 break; 283 } 284 /* discard the remaining bytes from the current packet */ 285 if (buf_len < sshbuf_len(iqueue)) { 286 error("iqueue grew unexpectedly"); 287 cleanup_exit(255); 288 } 289 consumed = buf_len - sshbuf_len(iqueue); 290 if (msg_len < consumed) { 291 error("msg_len %d < consumed %d", msg_len, consumed); 292 cleanup_exit(255); 293 } 294 if (msg_len > consumed) { 295 if ((r = sshbuf_consume(iqueue, msg_len - consumed)) != 0) 296 fatal_fr(r, "consume"); 297 } 298 } 299 300 void 301 cleanup_exit(int i) 302 { 303 /* XXX */ 304 _exit(i); 305 } 306 307 308 int 309 main(int argc, char **argv) 310 { 311 int r, ch, in, out, log_stderr = 0; 312 ssize_t len; 313 SyslogFacility log_facility = SYSLOG_FACILITY_AUTH; 314 LogLevel log_level = SYSLOG_LEVEL_ERROR; 315 char buf[4*4096]; 316 extern char *__progname; 317 struct pollfd pfd[2]; 318 319 TAILQ_INIT(&pkcs11_keylist); 320 321 log_init(__progname, log_level, log_facility, log_stderr); 322 323 while ((ch = getopt(argc, argv, "v")) != -1) { 324 switch (ch) { 325 case 'v': 326 log_stderr = 1; 327 if (log_level == SYSLOG_LEVEL_ERROR) 328 log_level = SYSLOG_LEVEL_DEBUG1; 329 else if (log_level < SYSLOG_LEVEL_DEBUG3) 330 log_level++; 331 break; 332 default: 333 fprintf(stderr, "usage: %s [-v]\n", __progname); 334 exit(1); 335 } 336 } 337 338 log_init(__progname, log_level, log_facility, log_stderr); 339 340 pkcs11_init(0); 341 in = STDIN_FILENO; 342 out = STDOUT_FILENO; 343 344 if ((iqueue = sshbuf_new()) == NULL) 345 fatal_f("sshbuf_new failed"); 346 if ((oqueue = sshbuf_new()) == NULL) 347 fatal_f("sshbuf_new failed"); 348 349 while (1) { 350 memset(pfd, 0, sizeof(pfd)); 351 pfd[0].fd = in; 352 pfd[1].fd = out; 353 354 /* 355 * Ensure that we can read a full buffer and handle 356 * the worst-case length packet it can generate, 357 * otherwise apply backpressure by stopping reads. 358 */ 359 if ((r = sshbuf_check_reserve(iqueue, sizeof(buf))) == 0 && 360 (r = sshbuf_check_reserve(oqueue, MAX_MSG_LENGTH)) == 0) 361 pfd[0].events = POLLIN; 362 else if (r != SSH_ERR_NO_BUFFER_SPACE) 363 fatal_fr(r, "reserve"); 364 365 if (sshbuf_len(oqueue) > 0) 366 pfd[1].events = POLLOUT; 367 368 if ((r = poll(pfd, 2, -1 /* INFTIM */)) <= 0) { 369 if (r == 0 || errno == EINTR) 370 continue; 371 fatal("poll: %s", strerror(errno)); 372 } 373 374 /* copy stdin to iqueue */ 375 if ((pfd[0].revents & (POLLIN|POLLHUP|POLLERR)) != 0) { 376 len = read(in, buf, sizeof buf); 377 if (len == 0) { 378 debug("read eof"); 379 cleanup_exit(0); 380 } else if (len < 0) { 381 error("read: %s", strerror(errno)); 382 cleanup_exit(1); 383 } else if ((r = sshbuf_put(iqueue, buf, len)) != 0) 384 fatal_fr(r, "sshbuf_put"); 385 } 386 /* send oqueue to stdout */ 387 if ((pfd[1].revents & (POLLOUT|POLLHUP)) != 0) { 388 len = write(out, sshbuf_ptr(oqueue), 389 sshbuf_len(oqueue)); 390 if (len < 0) { 391 error("write: %s", strerror(errno)); 392 cleanup_exit(1); 393 } else if ((r = sshbuf_consume(oqueue, len)) != 0) 394 fatal_fr(r, "consume"); 395 } 396 397 /* 398 * Process requests from client if we can fit the results 399 * into the output buffer, otherwise stop processing input 400 * and let the output queue drain. 401 */ 402 if ((r = sshbuf_check_reserve(oqueue, MAX_MSG_LENGTH)) == 0) 403 process(); 404 else if (r != SSH_ERR_NO_BUFFER_SPACE) 405 fatal_fr(r, "reserve"); 406 } 407 } 408 409 #else /* WITH_OPENSSL */ 410 void 411 cleanup_exit(int i) 412 { 413 _exit(i); 414 } 415 416 int 417 main(int argc, char **argv) 418 { 419 fprintf(stderr, "PKCS#11 code is not enabled\n"); 420 return 1; 421 } 422 #endif /* WITH_OPENSSL */ 423