1 /* $OpenBSD: ssh-pkcs11-helper.c,v 1.11 2015/08/20 22:32:42 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 <sys/types.h> 19 #include <sys/queue.h> 20 #include <sys/time.h> 21 22 #include <stdarg.h> 23 #include <string.h> 24 #include <unistd.h> 25 #include <errno.h> 26 27 #include "xmalloc.h" 28 #include "buffer.h" 29 #include "log.h" 30 #include "misc.h" 31 #include "key.h" 32 #include "authfd.h" 33 #include "ssh-pkcs11.h" 34 35 /* borrows code from sftp-server and ssh-agent */ 36 37 struct pkcs11_keyinfo { 38 Key *key; 39 char *providername; 40 TAILQ_ENTRY(pkcs11_keyinfo) next; 41 }; 42 43 TAILQ_HEAD(, pkcs11_keyinfo) pkcs11_keylist; 44 45 #define MAX_MSG_LENGTH 10240 /*XXX*/ 46 47 /* helper */ 48 #define get_int() buffer_get_int(&iqueue); 49 #define get_string(lenp) buffer_get_string(&iqueue, lenp); 50 51 /* input and output queue */ 52 Buffer iqueue; 53 Buffer oqueue; 54 55 static void 56 add_key(Key *k, char *name) 57 { 58 struct pkcs11_keyinfo *ki; 59 60 ki = xcalloc(1, sizeof(*ki)); 61 ki->providername = xstrdup(name); 62 ki->key = k; 63 TAILQ_INSERT_TAIL(&pkcs11_keylist, ki, next); 64 } 65 66 static void 67 del_keys_by_name(char *name) 68 { 69 struct pkcs11_keyinfo *ki, *nxt; 70 71 for (ki = TAILQ_FIRST(&pkcs11_keylist); ki; ki = nxt) { 72 nxt = TAILQ_NEXT(ki, next); 73 if (!strcmp(ki->providername, name)) { 74 TAILQ_REMOVE(&pkcs11_keylist, ki, next); 75 free(ki->providername); 76 key_free(ki->key); 77 free(ki); 78 } 79 } 80 } 81 82 /* lookup matching 'private' key */ 83 static Key * 84 lookup_key(Key *k) 85 { 86 struct pkcs11_keyinfo *ki; 87 88 TAILQ_FOREACH(ki, &pkcs11_keylist, next) { 89 debug("check %p %s", ki, ki->providername); 90 if (key_equal(k, ki->key)) 91 return (ki->key); 92 } 93 return (NULL); 94 } 95 96 static void 97 send_msg(Buffer *m) 98 { 99 int mlen = buffer_len(m); 100 101 buffer_put_int(&oqueue, mlen); 102 buffer_append(&oqueue, buffer_ptr(m), mlen); 103 buffer_consume(m, mlen); 104 } 105 106 static void 107 process_add(void) 108 { 109 char *name, *pin; 110 Key **keys; 111 int i, nkeys; 112 u_char *blob; 113 u_int blen; 114 Buffer msg; 115 116 buffer_init(&msg); 117 name = get_string(NULL); 118 pin = get_string(NULL); 119 if ((nkeys = pkcs11_add_provider(name, pin, &keys)) > 0) { 120 buffer_put_char(&msg, SSH2_AGENT_IDENTITIES_ANSWER); 121 buffer_put_int(&msg, nkeys); 122 for (i = 0; i < nkeys; i++) { 123 if (key_to_blob(keys[i], &blob, &blen) == 0) 124 continue; 125 buffer_put_string(&msg, blob, blen); 126 buffer_put_cstring(&msg, name); 127 free(blob); 128 add_key(keys[i], name); 129 } 130 free(keys); 131 } else { 132 buffer_put_char(&msg, SSH_AGENT_FAILURE); 133 } 134 free(pin); 135 free(name); 136 send_msg(&msg); 137 buffer_free(&msg); 138 } 139 140 static void 141 process_del(void) 142 { 143 char *name, *pin; 144 Buffer msg; 145 146 buffer_init(&msg); 147 name = get_string(NULL); 148 pin = get_string(NULL); 149 del_keys_by_name(name); 150 if (pkcs11_del_provider(name) == 0) 151 buffer_put_char(&msg, SSH_AGENT_SUCCESS); 152 else 153 buffer_put_char(&msg, SSH_AGENT_FAILURE); 154 free(pin); 155 free(name); 156 send_msg(&msg); 157 buffer_free(&msg); 158 } 159 160 static void 161 process_sign(void) 162 { 163 u_char *blob, *data, *signature = NULL; 164 u_int blen, dlen, slen = 0; 165 int ok = -1; 166 Key *key, *found; 167 Buffer msg; 168 169 blob = get_string(&blen); 170 data = get_string(&dlen); 171 (void)get_int(); /* XXX ignore flags */ 172 173 if ((key = key_from_blob(blob, blen)) != NULL) { 174 if ((found = lookup_key(key)) != NULL) { 175 #ifdef WITH_OPENSSL 176 int ret; 177 178 slen = RSA_size(key->rsa); 179 signature = xmalloc(slen); 180 if ((ret = RSA_private_encrypt(dlen, data, signature, 181 found->rsa, RSA_PKCS1_PADDING)) != -1) { 182 slen = ret; 183 ok = 0; 184 } 185 #endif /* WITH_OPENSSL */ 186 } 187 key_free(key); 188 } 189 buffer_init(&msg); 190 if (ok == 0) { 191 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE); 192 buffer_put_string(&msg, signature, slen); 193 } else { 194 buffer_put_char(&msg, SSH_AGENT_FAILURE); 195 } 196 free(data); 197 free(blob); 198 free(signature); 199 send_msg(&msg); 200 buffer_free(&msg); 201 } 202 203 static void 204 process(void) 205 { 206 u_int msg_len; 207 u_int buf_len; 208 u_int consumed; 209 u_int type; 210 u_char *cp; 211 212 buf_len = buffer_len(&iqueue); 213 if (buf_len < 5) 214 return; /* Incomplete message. */ 215 cp = buffer_ptr(&iqueue); 216 msg_len = get_u32(cp); 217 if (msg_len > MAX_MSG_LENGTH) { 218 error("bad message len %d", msg_len); 219 cleanup_exit(11); 220 } 221 if (buf_len < msg_len + 4) 222 return; 223 buffer_consume(&iqueue, 4); 224 buf_len -= 4; 225 type = buffer_get_char(&iqueue); 226 switch (type) { 227 case SSH_AGENTC_ADD_SMARTCARD_KEY: 228 debug("process_add"); 229 process_add(); 230 break; 231 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 232 debug("process_del"); 233 process_del(); 234 break; 235 case SSH2_AGENTC_SIGN_REQUEST: 236 debug("process_sign"); 237 process_sign(); 238 break; 239 default: 240 error("Unknown message %d", type); 241 break; 242 } 243 /* discard the remaining bytes from the current packet */ 244 if (buf_len < buffer_len(&iqueue)) { 245 error("iqueue grew unexpectedly"); 246 cleanup_exit(255); 247 } 248 consumed = buf_len - buffer_len(&iqueue); 249 if (msg_len < consumed) { 250 error("msg_len %d < consumed %d", msg_len, consumed); 251 cleanup_exit(255); 252 } 253 if (msg_len > consumed) 254 buffer_consume(&iqueue, msg_len - consumed); 255 } 256 257 void 258 cleanup_exit(int i) 259 { 260 /* XXX */ 261 _exit(i); 262 } 263 264 int 265 main(int argc, char **argv) 266 { 267 fd_set *rset, *wset; 268 int in, out, max, log_stderr = 0; 269 ssize_t len, olen, set_size; 270 SyslogFacility log_facility = SYSLOG_FACILITY_AUTH; 271 LogLevel log_level = SYSLOG_LEVEL_ERROR; 272 char buf[4*4096]; 273 extern char *__progname; 274 275 TAILQ_INIT(&pkcs11_keylist); 276 pkcs11_init(0); 277 278 log_init(__progname, log_level, log_facility, log_stderr); 279 280 in = STDIN_FILENO; 281 out = STDOUT_FILENO; 282 283 max = 0; 284 if (in > max) 285 max = in; 286 if (out > max) 287 max = out; 288 289 buffer_init(&iqueue); 290 buffer_init(&oqueue); 291 292 set_size = howmany(max + 1, NFDBITS) * sizeof(fd_mask); 293 rset = xmalloc(set_size); 294 wset = xmalloc(set_size); 295 296 for (;;) { 297 memset(rset, 0, set_size); 298 memset(wset, 0, set_size); 299 300 /* 301 * Ensure that we can read a full buffer and handle 302 * the worst-case length packet it can generate, 303 * otherwise apply backpressure by stopping reads. 304 */ 305 if (buffer_check_alloc(&iqueue, sizeof(buf)) && 306 buffer_check_alloc(&oqueue, MAX_MSG_LENGTH)) 307 FD_SET(in, rset); 308 309 olen = buffer_len(&oqueue); 310 if (olen > 0) 311 FD_SET(out, wset); 312 313 if (select(max+1, rset, wset, NULL, NULL) < 0) { 314 if (errno == EINTR) 315 continue; 316 error("select: %s", strerror(errno)); 317 cleanup_exit(2); 318 } 319 320 /* copy stdin to iqueue */ 321 if (FD_ISSET(in, rset)) { 322 len = read(in, buf, sizeof buf); 323 if (len == 0) { 324 debug("read eof"); 325 cleanup_exit(0); 326 } else if (len < 0) { 327 error("read: %s", strerror(errno)); 328 cleanup_exit(1); 329 } else { 330 buffer_append(&iqueue, buf, len); 331 } 332 } 333 /* send oqueue to stdout */ 334 if (FD_ISSET(out, wset)) { 335 len = write(out, buffer_ptr(&oqueue), olen); 336 if (len < 0) { 337 error("write: %s", strerror(errno)); 338 cleanup_exit(1); 339 } else { 340 buffer_consume(&oqueue, len); 341 } 342 } 343 344 /* 345 * Process requests from client if we can fit the results 346 * into the output buffer, otherwise stop processing input 347 * and let the output queue drain. 348 */ 349 if (buffer_check_alloc(&oqueue, MAX_MSG_LENGTH)) 350 process(); 351 } 352 } 353