1 /* $NetBSD: ssh-pkcs11-helper.c,v 1.13 2017/10/07 19:39:19 christos Exp $ */ 2 /* $OpenBSD: ssh-pkcs11-helper.c,v 1.13 2017/05/30 08:52:19 markus Exp $ */ 3 /* 4 * Copyright (c) 2010 Markus Friedl. All rights reserved. 5 * 6 * Permission to use, copy, modify, and distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 */ 18 #include "includes.h" 19 __RCSID("$NetBSD: ssh-pkcs11-helper.c,v 1.13 2017/10/07 19:39:19 christos Exp $"); 20 21 #include <sys/types.h> 22 #include <sys/queue.h> 23 #include <sys/time.h> 24 #include <sys/param.h> 25 26 #include <stdarg.h> 27 #include <string.h> 28 #include <unistd.h> 29 #include <errno.h> 30 31 #include "xmalloc.h" 32 #include "buffer.h" 33 #include "log.h" 34 #include "misc.h" 35 #include "key.h" 36 #include "authfd.h" 37 #include "ssh-pkcs11.h" 38 39 /* borrows code from sftp-server and ssh-agent */ 40 41 struct pkcs11_keyinfo { 42 struct sshkey *key; 43 char *providername; 44 TAILQ_ENTRY(pkcs11_keyinfo) next; 45 }; 46 47 TAILQ_HEAD(, pkcs11_keyinfo) pkcs11_keylist; 48 49 #define MAX_MSG_LENGTH 10240 /*XXX*/ 50 51 /* helper */ 52 #define get_int() buffer_get_int(&iqueue); 53 #define get_string(lenp) buffer_get_string(&iqueue, lenp); 54 55 /* input and output queue */ 56 Buffer iqueue; 57 Buffer oqueue; 58 59 static void 60 add_key(struct sshkey *k, char *name) 61 { 62 struct pkcs11_keyinfo *ki; 63 64 ki = xcalloc(1, sizeof(*ki)); 65 ki->providername = xstrdup(name); 66 ki->key = k; 67 TAILQ_INSERT_TAIL(&pkcs11_keylist, ki, next); 68 } 69 70 static void 71 del_keys_by_name(char *name) 72 { 73 struct pkcs11_keyinfo *ki, *nxt; 74 75 for (ki = TAILQ_FIRST(&pkcs11_keylist); ki; ki = nxt) { 76 nxt = TAILQ_NEXT(ki, next); 77 if (!strcmp(ki->providername, name)) { 78 TAILQ_REMOVE(&pkcs11_keylist, ki, next); 79 free(ki->providername); 80 key_free(ki->key); 81 free(ki); 82 } 83 } 84 } 85 86 /* lookup matching 'private' key */ 87 static struct sshkey * 88 lookup_key(struct sshkey *k) 89 { 90 struct pkcs11_keyinfo *ki; 91 92 TAILQ_FOREACH(ki, &pkcs11_keylist, next) { 93 debug("check %p %s", ki, ki->providername); 94 if (key_equal(k, ki->key)) 95 return (ki->key); 96 } 97 return (NULL); 98 } 99 100 static void 101 send_msg(Buffer *m) 102 { 103 int mlen = buffer_len(m); 104 105 buffer_put_int(&oqueue, mlen); 106 buffer_append(&oqueue, buffer_ptr(m), mlen); 107 buffer_consume(m, mlen); 108 } 109 110 static void 111 process_add(void) 112 { 113 char *name, *pin; 114 struct sshkey **keys; 115 int i, nkeys; 116 u_char *blob; 117 u_int blen; 118 Buffer msg; 119 120 buffer_init(&msg); 121 name = get_string(NULL); 122 pin = get_string(NULL); 123 if ((nkeys = pkcs11_add_provider(name, pin, &keys)) > 0) { 124 buffer_put_char(&msg, SSH2_AGENT_IDENTITIES_ANSWER); 125 buffer_put_int(&msg, nkeys); 126 for (i = 0; i < nkeys; i++) { 127 if (key_to_blob(keys[i], &blob, &blen) == 0) 128 continue; 129 buffer_put_string(&msg, blob, blen); 130 buffer_put_cstring(&msg, name); 131 free(blob); 132 add_key(keys[i], name); 133 } 134 free(keys); 135 } else { 136 buffer_put_char(&msg, SSH_AGENT_FAILURE); 137 } 138 free(pin); 139 free(name); 140 send_msg(&msg); 141 buffer_free(&msg); 142 } 143 144 static void 145 process_del(void) 146 { 147 char *name, *pin; 148 Buffer msg; 149 150 buffer_init(&msg); 151 name = get_string(NULL); 152 pin = get_string(NULL); 153 del_keys_by_name(name); 154 if (pkcs11_del_provider(name) == 0) 155 buffer_put_char(&msg, SSH_AGENT_SUCCESS); 156 else 157 buffer_put_char(&msg, SSH_AGENT_FAILURE); 158 free(pin); 159 free(name); 160 send_msg(&msg); 161 buffer_free(&msg); 162 } 163 164 static void 165 process_sign(void) 166 { 167 u_char *blob, *data, *signature = NULL; 168 u_int blen, dlen, slen = 0; 169 int ok = -1; 170 struct sshkey *key, *found; 171 Buffer msg; 172 173 blob = get_string(&blen); 174 data = get_string(&dlen); 175 (void)get_int(); /* XXX ignore flags */ 176 177 if ((key = key_from_blob(blob, blen)) != NULL) { 178 if ((found = lookup_key(key)) != NULL) { 179 #ifdef WITH_OPENSSL 180 int ret; 181 182 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 #endif /* WITH_OPENSSL */ 190 } 191 key_free(key); 192 } 193 buffer_init(&msg); 194 if (ok == 0) { 195 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE); 196 buffer_put_string(&msg, signature, slen); 197 } else { 198 buffer_put_char(&msg, SSH_AGENT_FAILURE); 199 } 200 free(data); 201 free(blob); 202 free(signature); 203 send_msg(&msg); 204 buffer_free(&msg); 205 } 206 207 static void 208 process(void) 209 { 210 u_int msg_len; 211 u_int buf_len; 212 u_int consumed; 213 u_int type; 214 u_char *cp; 215 216 buf_len = buffer_len(&iqueue); 217 if (buf_len < 5) 218 return; /* Incomplete message. */ 219 cp = buffer_ptr(&iqueue); 220 msg_len = get_u32(cp); 221 if (msg_len > MAX_MSG_LENGTH) { 222 error("bad message len %d", msg_len); 223 cleanup_exit(11); 224 } 225 if (buf_len < msg_len + 4) 226 return; 227 buffer_consume(&iqueue, 4); 228 buf_len -= 4; 229 type = buffer_get_char(&iqueue); 230 switch (type) { 231 case SSH_AGENTC_ADD_SMARTCARD_KEY: 232 debug("process_add"); 233 process_add(); 234 break; 235 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 236 debug("process_del"); 237 process_del(); 238 break; 239 case SSH2_AGENTC_SIGN_REQUEST: 240 debug("process_sign"); 241 process_sign(); 242 break; 243 default: 244 error("Unknown message %d", type); 245 break; 246 } 247 /* discard the remaining bytes from the current packet */ 248 if (buf_len < buffer_len(&iqueue)) { 249 error("iqueue grew unexpectedly"); 250 cleanup_exit(255); 251 } 252 consumed = buf_len - buffer_len(&iqueue); 253 if (msg_len < consumed) { 254 error("msg_len %d < consumed %d", msg_len, consumed); 255 cleanup_exit(255); 256 } 257 if (msg_len > consumed) 258 buffer_consume(&iqueue, msg_len - consumed); 259 } 260 261 void 262 cleanup_exit(int i) 263 { 264 /* XXX */ 265 _exit(i); 266 } 267 268 int 269 main(int argc, char **argv) 270 { 271 fd_set *rset, *wset; 272 int in, out, max, log_stderr = 0; 273 ssize_t len, olen, set_size; 274 SyslogFacility log_facility = SYSLOG_FACILITY_AUTH; 275 LogLevel log_level = SYSLOG_LEVEL_ERROR; 276 char buf[4*4096]; 277 extern char *__progname; 278 279 ssh_malloc_init(); /* must be called before any mallocs */ 280 TAILQ_INIT(&pkcs11_keylist); 281 pkcs11_init(0); 282 283 log_init(__progname, log_level, log_facility, log_stderr); 284 285 in = STDIN_FILENO; 286 out = STDOUT_FILENO; 287 288 max = 0; 289 if (in > max) 290 max = in; 291 if (out > max) 292 max = out; 293 294 buffer_init(&iqueue); 295 buffer_init(&oqueue); 296 297 set_size = howmany(max + 1, NFDBITS) * sizeof(fd_mask); 298 rset = xmalloc(set_size); 299 wset = xmalloc(set_size); 300 301 for (;;) { 302 memset(rset, 0, set_size); 303 memset(wset, 0, set_size); 304 305 /* 306 * Ensure that we can read a full buffer and handle 307 * the worst-case length packet it can generate, 308 * otherwise apply backpressure by stopping reads. 309 */ 310 if (buffer_check_alloc(&iqueue, sizeof(buf)) && 311 buffer_check_alloc(&oqueue, MAX_MSG_LENGTH)) 312 FD_SET(in, rset); 313 314 olen = buffer_len(&oqueue); 315 if (olen > 0) 316 FD_SET(out, wset); 317 318 if (select(max+1, rset, wset, NULL, NULL) < 0) { 319 if (errno == EINTR) 320 continue; 321 error("select: %s", strerror(errno)); 322 cleanup_exit(2); 323 } 324 325 /* copy stdin to iqueue */ 326 if (FD_ISSET(in, rset)) { 327 len = read(in, buf, sizeof buf); 328 if (len == 0) { 329 debug("read eof"); 330 cleanup_exit(0); 331 } else if (len < 0) { 332 error("read: %s", strerror(errno)); 333 cleanup_exit(1); 334 } else { 335 buffer_append(&iqueue, buf, len); 336 } 337 } 338 /* send oqueue to stdout */ 339 if (FD_ISSET(out, wset)) { 340 len = write(out, buffer_ptr(&oqueue), olen); 341 if (len < 0) { 342 error("write: %s", strerror(errno)); 343 cleanup_exit(1); 344 } else { 345 buffer_consume(&oqueue, len); 346 } 347 } 348 349 /* 350 * Process requests from client if we can fit the results 351 * into the output buffer, otherwise stop processing input 352 * and let the output queue drain. 353 */ 354 if (buffer_check_alloc(&oqueue, MAX_MSG_LENGTH)) 355 process(); 356 } 357 } 358