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 <sys/queue.h> 19 #include <sys/types.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 xfree(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 key_to_blob(keys[i], &blob, &blen); 124 buffer_put_string(&msg, blob, blen); 125 buffer_put_cstring(&msg, name); 126 xfree(blob); 127 add_key(keys[i], name); 128 } 129 xfree(keys); 130 } else { 131 buffer_put_char(&msg, SSH_AGENT_FAILURE); 132 } 133 xfree(pin); 134 xfree(name); 135 send_msg(&msg); 136 buffer_free(&msg); 137 } 138 139 static void 140 process_del(void) 141 { 142 char *name, *pin; 143 Buffer msg; 144 145 buffer_init(&msg); 146 name = get_string(NULL); 147 pin = get_string(NULL); 148 del_keys_by_name(name); 149 if (pkcs11_del_provider(name) == 0) 150 buffer_put_char(&msg, SSH_AGENT_SUCCESS); 151 else 152 buffer_put_char(&msg, SSH_AGENT_FAILURE); 153 xfree(pin); 154 xfree(name); 155 send_msg(&msg); 156 buffer_free(&msg); 157 } 158 159 static void 160 process_sign(void) 161 { 162 u_char *blob, *data, *signature = NULL; 163 u_int blen, dlen, slen = 0; 164 int ok = -1, flags, ret; 165 Key *key, *found; 166 Buffer msg; 167 168 blob = get_string(&blen); 169 data = get_string(&dlen); 170 flags = get_int(); /* XXX ignore */ 171 172 if ((key = key_from_blob(blob, blen)) != NULL) { 173 if ((found = lookup_key(key)) != NULL) { 174 slen = RSA_size(key->rsa); 175 signature = xmalloc(slen); 176 if ((ret = RSA_private_encrypt(dlen, data, signature, 177 found->rsa, RSA_PKCS1_PADDING)) != -1) { 178 slen = ret; 179 ok = 0; 180 } 181 } 182 key_free(key); 183 } 184 buffer_init(&msg); 185 if (ok == 0) { 186 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE); 187 buffer_put_string(&msg, signature, slen); 188 } else { 189 buffer_put_char(&msg, SSH_AGENT_FAILURE); 190 } 191 xfree(data); 192 xfree(blob); 193 if (signature != NULL) 194 xfree(signature); 195 send_msg(&msg); 196 buffer_free(&msg); 197 } 198 199 static void 200 process(void) 201 { 202 u_int msg_len; 203 u_int buf_len; 204 u_int consumed; 205 u_int type; 206 u_char *cp; 207 208 buf_len = buffer_len(&iqueue); 209 if (buf_len < 5) 210 return; /* Incomplete message. */ 211 cp = buffer_ptr(&iqueue); 212 msg_len = get_u32(cp); 213 if (msg_len > MAX_MSG_LENGTH) { 214 error("bad message len %d", msg_len); 215 cleanup_exit(11); 216 } 217 if (buf_len < msg_len + 4) 218 return; 219 buffer_consume(&iqueue, 4); 220 buf_len -= 4; 221 type = buffer_get_char(&iqueue); 222 switch (type) { 223 case SSH_AGENTC_ADD_SMARTCARD_KEY: 224 debug("process_add"); 225 process_add(); 226 break; 227 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 228 debug("process_del"); 229 process_del(); 230 break; 231 case SSH2_AGENTC_SIGN_REQUEST: 232 debug("process_sign"); 233 process_sign(); 234 break; 235 default: 236 error("Unknown message %d", type); 237 break; 238 } 239 /* discard the remaining bytes from the current packet */ 240 if (buf_len < buffer_len(&iqueue)) { 241 error("iqueue grew unexpectedly"); 242 cleanup_exit(255); 243 } 244 consumed = buf_len - buffer_len(&iqueue); 245 if (msg_len < consumed) { 246 error("msg_len %d < consumed %d", msg_len, consumed); 247 cleanup_exit(255); 248 } 249 if (msg_len > consumed) 250 buffer_consume(&iqueue, msg_len - consumed); 251 } 252 253 void 254 cleanup_exit(int i) 255 { 256 /* XXX */ 257 _exit(i); 258 } 259 260 int 261 main(int argc, char **argv) 262 { 263 fd_set *rset, *wset; 264 int in, out, max, log_stderr = 0; 265 ssize_t len, olen, set_size; 266 SyslogFacility log_facility = SYSLOG_FACILITY_AUTH; 267 LogLevel log_level = SYSLOG_LEVEL_ERROR; 268 char buf[4*4096]; 269 extern char *optarg; 270 extern char *__progname; 271 272 TAILQ_INIT(&pkcs11_keylist); 273 pkcs11_init(0); 274 275 log_init(__progname, log_level, log_facility, log_stderr); 276 277 in = STDIN_FILENO; 278 out = STDOUT_FILENO; 279 280 max = 0; 281 if (in > max) 282 max = in; 283 if (out > max) 284 max = out; 285 286 buffer_init(&iqueue); 287 buffer_init(&oqueue); 288 289 set_size = howmany(max + 1, NFDBITS) * sizeof(fd_mask); 290 rset = (fd_set *)xmalloc(set_size); 291 wset = (fd_set *)xmalloc(set_size); 292 293 for (;;) { 294 memset(rset, 0, set_size); 295 memset(wset, 0, set_size); 296 297 /* 298 * Ensure that we can read a full buffer and handle 299 * the worst-case length packet it can generate, 300 * otherwise apply backpressure by stopping reads. 301 */ 302 if (buffer_check_alloc(&iqueue, sizeof(buf)) && 303 buffer_check_alloc(&oqueue, MAX_MSG_LENGTH)) 304 FD_SET(in, rset); 305 306 olen = buffer_len(&oqueue); 307 if (olen > 0) 308 FD_SET(out, wset); 309 310 if (select(max+1, rset, wset, NULL, NULL) < 0) { 311 if (errno == EINTR) 312 continue; 313 error("select: %s", strerror(errno)); 314 cleanup_exit(2); 315 } 316 317 /* copy stdin to iqueue */ 318 if (FD_ISSET(in, rset)) { 319 len = read(in, buf, sizeof buf); 320 if (len == 0) { 321 debug("read eof"); 322 cleanup_exit(0); 323 } else if (len < 0) { 324 error("read: %s", strerror(errno)); 325 cleanup_exit(1); 326 } else { 327 buffer_append(&iqueue, buf, len); 328 } 329 } 330 /* send oqueue to stdout */ 331 if (FD_ISSET(out, wset)) { 332 len = write(out, buffer_ptr(&oqueue), olen); 333 if (len < 0) { 334 error("write: %s", strerror(errno)); 335 cleanup_exit(1); 336 } else { 337 buffer_consume(&oqueue, len); 338 } 339 } 340 341 /* 342 * Process requests from client if we can fit the results 343 * into the output buffer, otherwise stop processing input 344 * and let the output queue drain. 345 */ 346 if (buffer_check_alloc(&oqueue, MAX_MSG_LENGTH)) 347 process(); 348 } 349 } 350