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 <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 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, ret; 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 slen = RSA_size(key->rsa); 176 signature = xmalloc(slen); 177 if ((ret = RSA_private_encrypt(dlen, data, signature, 178 found->rsa, RSA_PKCS1_PADDING)) != -1) { 179 slen = ret; 180 ok = 0; 181 } 182 } 183 key_free(key); 184 } 185 buffer_init(&msg); 186 if (ok == 0) { 187 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE); 188 buffer_put_string(&msg, signature, slen); 189 } else { 190 buffer_put_char(&msg, SSH_AGENT_FAILURE); 191 } 192 free(data); 193 free(blob); 194 free(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 *__progname; 270 271 TAILQ_INIT(&pkcs11_keylist); 272 pkcs11_init(0); 273 274 log_init(__progname, log_level, log_facility, log_stderr); 275 276 in = STDIN_FILENO; 277 out = STDOUT_FILENO; 278 279 max = 0; 280 if (in > max) 281 max = in; 282 if (out > max) 283 max = out; 284 285 buffer_init(&iqueue); 286 buffer_init(&oqueue); 287 288 set_size = howmany(max + 1, NFDBITS) * sizeof(fd_mask); 289 rset = (fd_set *)xmalloc(set_size); 290 wset = (fd_set *)xmalloc(set_size); 291 292 for (;;) { 293 memset(rset, 0, set_size); 294 memset(wset, 0, set_size); 295 296 /* 297 * Ensure that we can read a full buffer and handle 298 * the worst-case length packet it can generate, 299 * otherwise apply backpressure by stopping reads. 300 */ 301 if (buffer_check_alloc(&iqueue, sizeof(buf)) && 302 buffer_check_alloc(&oqueue, MAX_MSG_LENGTH)) 303 FD_SET(in, rset); 304 305 olen = buffer_len(&oqueue); 306 if (olen > 0) 307 FD_SET(out, wset); 308 309 if (select(max+1, rset, wset, NULL, NULL) < 0) { 310 if (errno == EINTR) 311 continue; 312 error("select: %s", strerror(errno)); 313 cleanup_exit(2); 314 } 315 316 /* copy stdin to iqueue */ 317 if (FD_ISSET(in, rset)) { 318 len = read(in, buf, sizeof buf); 319 if (len == 0) { 320 debug("read eof"); 321 cleanup_exit(0); 322 } else if (len < 0) { 323 error("read: %s", strerror(errno)); 324 cleanup_exit(1); 325 } else { 326 buffer_append(&iqueue, buf, len); 327 } 328 } 329 /* send oqueue to stdout */ 330 if (FD_ISSET(out, wset)) { 331 len = write(out, buffer_ptr(&oqueue), olen); 332 if (len < 0) { 333 error("write: %s", strerror(errno)); 334 cleanup_exit(1); 335 } else { 336 buffer_consume(&oqueue, len); 337 } 338 } 339 340 /* 341 * Process requests from client if we can fit the results 342 * into the output buffer, otherwise stop processing input 343 * and let the output queue drain. 344 */ 345 if (buffer_check_alloc(&oqueue, MAX_MSG_LENGTH)) 346 process(); 347 } 348 } 349