1 /* $OpenBSD: ssh-pkcs11-helper.c,v 1.7 2013/12/02 02:56:17 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 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, ret; 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 slen = RSA_size(key->rsa); 183 signature = xmalloc(slen); 184 if ((ret = RSA_private_encrypt(dlen, data, signature, 185 found->rsa, RSA_PKCS1_PADDING)) != -1) { 186 slen = ret; 187 ok = 0; 188 } 189 } 190 key_free(key); 191 } 192 buffer_init(&msg); 193 if (ok == 0) { 194 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE); 195 buffer_put_string(&msg, signature, slen); 196 } else { 197 buffer_put_char(&msg, SSH_AGENT_FAILURE); 198 } 199 free(data); 200 free(blob); 201 free(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 *__progname; 278 279 TAILQ_INIT(&pkcs11_keylist); 280 pkcs11_init(0); 281 282 seed_rng(); 283 __progname = ssh_get_progname(argv[0]); 284 285 log_init(__progname, log_level, log_facility, log_stderr); 286 287 in = STDIN_FILENO; 288 out = STDOUT_FILENO; 289 290 max = 0; 291 if (in > max) 292 max = in; 293 if (out > max) 294 max = out; 295 296 buffer_init(&iqueue); 297 buffer_init(&oqueue); 298 299 set_size = howmany(max + 1, NFDBITS) * sizeof(fd_mask); 300 rset = (fd_set *)xmalloc(set_size); 301 wset = (fd_set *)xmalloc(set_size); 302 303 for (;;) { 304 memset(rset, 0, set_size); 305 memset(wset, 0, set_size); 306 307 /* 308 * Ensure that we can read a full buffer and handle 309 * the worst-case length packet it can generate, 310 * otherwise apply backpressure by stopping reads. 311 */ 312 if (buffer_check_alloc(&iqueue, sizeof(buf)) && 313 buffer_check_alloc(&oqueue, MAX_MSG_LENGTH)) 314 FD_SET(in, rset); 315 316 olen = buffer_len(&oqueue); 317 if (olen > 0) 318 FD_SET(out, wset); 319 320 if (select(max+1, rset, wset, NULL, NULL) < 0) { 321 if (errno == EINTR) 322 continue; 323 error("select: %s", strerror(errno)); 324 cleanup_exit(2); 325 } 326 327 /* copy stdin to iqueue */ 328 if (FD_ISSET(in, rset)) { 329 len = read(in, buf, sizeof buf); 330 if (len == 0) { 331 debug("read eof"); 332 cleanup_exit(0); 333 } else if (len < 0) { 334 error("read: %s", strerror(errno)); 335 cleanup_exit(1); 336 } else { 337 buffer_append(&iqueue, buf, len); 338 } 339 } 340 /* send oqueue to stdout */ 341 if (FD_ISSET(out, wset)) { 342 len = write(out, buffer_ptr(&oqueue), olen); 343 if (len < 0) { 344 error("write: %s", strerror(errno)); 345 cleanup_exit(1); 346 } else { 347 buffer_consume(&oqueue, len); 348 } 349 } 350 351 /* 352 * Process requests from client if we can fit the results 353 * into the output buffer, otherwise stop processing input 354 * and let the output queue drain. 355 */ 356 if (buffer_check_alloc(&oqueue, MAX_MSG_LENGTH)) 357 process(); 358 } 359 } 360 #else /* ENABLE_PKCS11 */ 361 int 362 main(int argc, char **argv) 363 { 364 extern char *__progname; 365 366 __progname = ssh_get_progname(argv[0]); 367 log_init(__progname, SYSLOG_LEVEL_ERROR, SYSLOG_FACILITY_AUTH, 0); 368 fatal("PKCS#11 support disabled at compile time"); 369 } 370 #endif /* ENABLE_PKCS11 */ 371