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 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 xfree(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 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 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 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 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 261 cleanup_exit(int i) 262 { 263 /* XXX */ 264 _exit(i); 265 } 266 267 int 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 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