1 /* $OpenBSD: ssh-pkcs11-helper.c,v 1.10 2015/01/20 23:14:00 deraadt 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 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 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 free(ki->providername); 83 key_free(ki->key); 84 free(ki); 85 } 86 } 87 } 88 89 /* lookup matching 'private' key */ 90 static Key * 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 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 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 if (key_to_blob(keys[i], &blob, &blen) == 0) 131 continue; 132 buffer_put_string(&msg, blob, blen); 133 buffer_put_cstring(&msg, name); 134 free(blob); 135 add_key(keys[i], name); 136 } 137 free(keys); 138 } else { 139 buffer_put_char(&msg, SSH_AGENT_FAILURE); 140 } 141 free(pin); 142 free(name); 143 send_msg(&msg); 144 buffer_free(&msg); 145 } 146 147 static void 148 process_del(void) 149 { 150 char *name, *pin; 151 Buffer msg; 152 153 buffer_init(&msg); 154 name = get_string(NULL); 155 pin = get_string(NULL); 156 del_keys_by_name(name); 157 if (pkcs11_del_provider(name) == 0) 158 buffer_put_char(&msg, SSH_AGENT_SUCCESS); 159 else 160 buffer_put_char(&msg, SSH_AGENT_FAILURE); 161 free(pin); 162 free(name); 163 send_msg(&msg); 164 buffer_free(&msg); 165 } 166 167 static void 168 process_sign(void) 169 { 170 u_char *blob, *data, *signature = NULL; 171 u_int blen, dlen, slen = 0; 172 int ok = -1; 173 Key *key, *found; 174 Buffer msg; 175 176 blob = get_string(&blen); 177 data = get_string(&dlen); 178 (void)get_int(); /* XXX ignore flags */ 179 180 if ((key = key_from_blob(blob, blen)) != NULL) { 181 if ((found = lookup_key(key)) != NULL) { 182 #ifdef WITH_OPENSSL 183 int ret; 184 185 slen = RSA_size(key->rsa); 186 signature = xmalloc(slen); 187 if ((ret = RSA_private_encrypt(dlen, data, signature, 188 found->rsa, RSA_PKCS1_PADDING)) != -1) { 189 slen = ret; 190 ok = 0; 191 } 192 #endif /* WITH_OPENSSL */ 193 } 194 key_free(key); 195 } 196 buffer_init(&msg); 197 if (ok == 0) { 198 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE); 199 buffer_put_string(&msg, signature, slen); 200 } else { 201 buffer_put_char(&msg, SSH_AGENT_FAILURE); 202 } 203 free(data); 204 free(blob); 205 free(signature); 206 send_msg(&msg); 207 buffer_free(&msg); 208 } 209 210 static void 211 process(void) 212 { 213 u_int msg_len; 214 u_int buf_len; 215 u_int consumed; 216 u_int type; 217 u_char *cp; 218 219 buf_len = buffer_len(&iqueue); 220 if (buf_len < 5) 221 return; /* Incomplete message. */ 222 cp = buffer_ptr(&iqueue); 223 msg_len = get_u32(cp); 224 if (msg_len > MAX_MSG_LENGTH) { 225 error("bad message len %d", msg_len); 226 cleanup_exit(11); 227 } 228 if (buf_len < msg_len + 4) 229 return; 230 buffer_consume(&iqueue, 4); 231 buf_len -= 4; 232 type = buffer_get_char(&iqueue); 233 switch (type) { 234 case SSH_AGENTC_ADD_SMARTCARD_KEY: 235 debug("process_add"); 236 process_add(); 237 break; 238 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 239 debug("process_del"); 240 process_del(); 241 break; 242 case SSH2_AGENTC_SIGN_REQUEST: 243 debug("process_sign"); 244 process_sign(); 245 break; 246 default: 247 error("Unknown message %d", type); 248 break; 249 } 250 /* discard the remaining bytes from the current packet */ 251 if (buf_len < buffer_len(&iqueue)) { 252 error("iqueue grew unexpectedly"); 253 cleanup_exit(255); 254 } 255 consumed = buf_len - buffer_len(&iqueue); 256 if (msg_len < consumed) { 257 error("msg_len %d < consumed %d", msg_len, consumed); 258 cleanup_exit(255); 259 } 260 if (msg_len > consumed) 261 buffer_consume(&iqueue, msg_len - consumed); 262 } 263 264 void 265 cleanup_exit(int i) 266 { 267 /* XXX */ 268 _exit(i); 269 } 270 271 int 272 main(int argc, char **argv) 273 { 274 fd_set *rset, *wset; 275 int in, out, max, log_stderr = 0; 276 ssize_t len, olen, set_size; 277 SyslogFacility log_facility = SYSLOG_FACILITY_AUTH; 278 LogLevel log_level = SYSLOG_LEVEL_ERROR; 279 char buf[4*4096]; 280 281 extern char *__progname; 282 283 TAILQ_INIT(&pkcs11_keylist); 284 pkcs11_init(0); 285 286 seed_rng(); 287 __progname = ssh_get_progname(argv[0]); 288 289 log_init(__progname, log_level, log_facility, log_stderr); 290 291 in = STDIN_FILENO; 292 out = STDOUT_FILENO; 293 294 max = 0; 295 if (in > max) 296 max = in; 297 if (out > max) 298 max = out; 299 300 buffer_init(&iqueue); 301 buffer_init(&oqueue); 302 303 set_size = howmany(max + 1, NFDBITS) * sizeof(fd_mask); 304 rset = (fd_set *)xmalloc(set_size); 305 wset = (fd_set *)xmalloc(set_size); 306 307 for (;;) { 308 memset(rset, 0, set_size); 309 memset(wset, 0, set_size); 310 311 /* 312 * Ensure that we can read a full buffer and handle 313 * the worst-case length packet it can generate, 314 * otherwise apply backpressure by stopping reads. 315 */ 316 if (buffer_check_alloc(&iqueue, sizeof(buf)) && 317 buffer_check_alloc(&oqueue, MAX_MSG_LENGTH)) 318 FD_SET(in, rset); 319 320 olen = buffer_len(&oqueue); 321 if (olen > 0) 322 FD_SET(out, wset); 323 324 if (select(max+1, rset, wset, NULL, NULL) < 0) { 325 if (errno == EINTR) 326 continue; 327 error("select: %s", strerror(errno)); 328 cleanup_exit(2); 329 } 330 331 /* copy stdin to iqueue */ 332 if (FD_ISSET(in, rset)) { 333 len = read(in, buf, sizeof buf); 334 if (len == 0) { 335 debug("read eof"); 336 cleanup_exit(0); 337 } else if (len < 0) { 338 error("read: %s", strerror(errno)); 339 cleanup_exit(1); 340 } else { 341 buffer_append(&iqueue, buf, len); 342 } 343 } 344 /* send oqueue to stdout */ 345 if (FD_ISSET(out, wset)) { 346 len = write(out, buffer_ptr(&oqueue), olen); 347 if (len < 0) { 348 error("write: %s", strerror(errno)); 349 cleanup_exit(1); 350 } else { 351 buffer_consume(&oqueue, len); 352 } 353 } 354 355 /* 356 * Process requests from client if we can fit the results 357 * into the output buffer, otherwise stop processing input 358 * and let the output queue drain. 359 */ 360 if (buffer_check_alloc(&oqueue, MAX_MSG_LENGTH)) 361 process(); 362 } 363 } 364 #else /* ENABLE_PKCS11 */ 365 int 366 main(int argc, char **argv) 367 { 368 extern char *__progname; 369 370 __progname = ssh_get_progname(argv[0]); 371 log_init(__progname, SYSLOG_LEVEL_ERROR, SYSLOG_FACILITY_AUTH, 0); 372 fatal("PKCS#11 support disabled at compile time"); 373 } 374 #endif /* ENABLE_PKCS11 */ 375
