Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame^] | 1 | /* |
| 2 | |
| 3 | authfd.c |
| 4 | |
| 5 | Author: Tatu Ylonen <ylo@cs.hut.fi> |
| 6 | |
| 7 | Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
| 8 | All rights reserved |
| 9 | |
| 10 | Created: Wed Mar 29 01:30:28 1995 ylo |
| 11 | |
| 12 | Functions for connecting the local authentication agent. |
| 13 | |
| 14 | */ |
| 15 | |
| 16 | #include "includes.h" |
| 17 | RCSID("$Id: authfd.c,v 1.1 1999/10/27 03:42:43 damien Exp $"); |
| 18 | |
| 19 | #include "ssh.h" |
| 20 | #include "rsa.h" |
| 21 | #include "authfd.h" |
| 22 | #include "buffer.h" |
| 23 | #include "bufaux.h" |
| 24 | #include "xmalloc.h" |
| 25 | #include "getput.h" |
| 26 | |
| 27 | #include <openssl/rsa.h> |
| 28 | |
| 29 | /* Returns the number of the authentication fd, or -1 if there is none. */ |
| 30 | |
| 31 | int |
| 32 | ssh_get_authentication_socket() |
| 33 | { |
| 34 | const char *authsocket; |
| 35 | int sock; |
| 36 | struct sockaddr_un sunaddr; |
| 37 | |
| 38 | authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME); |
| 39 | if (!authsocket) |
| 40 | return -1; |
| 41 | |
| 42 | sunaddr.sun_family = AF_UNIX; |
| 43 | strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path)); |
| 44 | |
| 45 | sock = socket(AF_UNIX, SOCK_STREAM, 0); |
| 46 | if (sock < 0) |
| 47 | return -1; |
| 48 | |
| 49 | if (connect(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0) |
| 50 | { |
| 51 | close(sock); |
| 52 | return -1; |
| 53 | } |
| 54 | |
| 55 | return sock; |
| 56 | } |
| 57 | |
| 58 | /* Closes the agent socket if it should be closed (depends on how it was |
| 59 | obtained). The argument must have been returned by |
| 60 | ssh_get_authentication_socket(). */ |
| 61 | |
| 62 | void ssh_close_authentication_socket(int sock) |
| 63 | { |
| 64 | if (getenv(SSH_AUTHSOCKET_ENV_NAME)) |
| 65 | close(sock); |
| 66 | } |
| 67 | |
| 68 | /* Opens and connects a private socket for communication with the |
| 69 | authentication agent. Returns the file descriptor (which must be |
| 70 | shut down and closed by the caller when no longer needed). |
| 71 | Returns NULL if an error occurred and the connection could not be |
| 72 | opened. */ |
| 73 | |
| 74 | AuthenticationConnection *ssh_get_authentication_connection() |
| 75 | { |
| 76 | AuthenticationConnection *auth; |
| 77 | int sock; |
| 78 | |
| 79 | sock = ssh_get_authentication_socket(); |
| 80 | |
| 81 | /* Fail if we couldn't obtain a connection. This happens if we exited |
| 82 | due to a timeout. */ |
| 83 | if (sock < 0) |
| 84 | return NULL; |
| 85 | |
| 86 | /* Applocate the connection structure and initialize it. */ |
| 87 | auth = xmalloc(sizeof(*auth)); |
| 88 | auth->fd = sock; |
| 89 | buffer_init(&auth->packet); |
| 90 | buffer_init(&auth->identities); |
| 91 | auth->howmany = 0; |
| 92 | |
| 93 | return auth; |
| 94 | } |
| 95 | |
| 96 | /* Closes the connection to the authentication agent and frees any associated |
| 97 | memory. */ |
| 98 | |
| 99 | void ssh_close_authentication_connection(AuthenticationConnection *ac) |
| 100 | { |
| 101 | buffer_free(&ac->packet); |
| 102 | buffer_free(&ac->identities); |
| 103 | close(ac->fd); |
| 104 | /* Free the connection data structure. */ |
| 105 | xfree(ac); |
| 106 | } |
| 107 | |
| 108 | /* Returns the first authentication identity held by the agent. |
| 109 | Returns true if an identity is available, 0 otherwise. |
| 110 | The caller must initialize the integers before the call, and free the |
| 111 | comment after a successful call (before calling ssh_get_next_identity). */ |
| 112 | |
| 113 | int |
| 114 | ssh_get_first_identity(AuthenticationConnection *auth, |
| 115 | int *bitsp, BIGNUM *e, BIGNUM *n, char **comment) |
| 116 | { |
| 117 | unsigned char msg[8192]; |
| 118 | int len, l; |
| 119 | |
| 120 | /* Send a message to the agent requesting for a list of the identities |
| 121 | it can represent. */ |
| 122 | msg[0] = 0; |
| 123 | msg[1] = 0; |
| 124 | msg[2] = 0; |
| 125 | msg[3] = 1; |
| 126 | msg[4] = SSH_AGENTC_REQUEST_RSA_IDENTITIES; |
| 127 | if (write(auth->fd, msg, 5) != 5) |
| 128 | { |
| 129 | error("write auth->fd: %.100s", strerror(errno)); |
| 130 | return 0; |
| 131 | } |
| 132 | |
| 133 | /* Read the length of the response. XXX implement timeouts here. */ |
| 134 | len = 4; |
| 135 | while (len > 0) |
| 136 | { |
| 137 | l = read(auth->fd, msg + 4 - len, len); |
| 138 | if (l <= 0) |
| 139 | { |
| 140 | error("read auth->fd: %.100s", strerror(errno)); |
| 141 | return 0; |
| 142 | } |
| 143 | len -= l; |
| 144 | } |
| 145 | |
| 146 | /* Extract the length, and check it for sanity. (We cannot trust |
| 147 | authentication agents). */ |
| 148 | len = GET_32BIT(msg); |
| 149 | if (len < 1 || len > 256*1024) |
| 150 | fatal("Authentication reply message too long: %d\n", len); |
| 151 | |
| 152 | /* Read the packet itself. */ |
| 153 | buffer_clear(&auth->identities); |
| 154 | while (len > 0) |
| 155 | { |
| 156 | l = len; |
| 157 | if (l > sizeof(msg)) |
| 158 | l = sizeof(msg); |
| 159 | l = read(auth->fd, msg, l); |
| 160 | if (l <= 0) |
| 161 | fatal("Incomplete authentication reply."); |
| 162 | buffer_append(&auth->identities, (char *)msg, l); |
| 163 | len -= l; |
| 164 | } |
| 165 | |
| 166 | /* Get message type, and verify that we got a proper answer. */ |
| 167 | buffer_get(&auth->identities, (char *)msg, 1); |
| 168 | if (msg[0] != SSH_AGENT_RSA_IDENTITIES_ANSWER) |
| 169 | fatal("Bad authentication reply message type: %d", msg[0]); |
| 170 | |
| 171 | /* Get the number of entries in the response and check it for sanity. */ |
| 172 | auth->howmany = buffer_get_int(&auth->identities); |
| 173 | if (auth->howmany > 1024) |
| 174 | fatal("Too many identities in authentication reply: %d\n", auth->howmany); |
| 175 | |
| 176 | /* Return the first entry (if any). */ |
| 177 | return ssh_get_next_identity(auth, bitsp, e, n, comment); |
| 178 | } |
| 179 | |
| 180 | /* Returns the next authentication identity for the agent. Other functions |
| 181 | can be called between this and ssh_get_first_identity or two calls of this |
| 182 | function. This returns 0 if there are no more identities. The caller |
| 183 | must free comment after a successful return. */ |
| 184 | |
| 185 | int |
| 186 | ssh_get_next_identity(AuthenticationConnection *auth, |
| 187 | int *bitsp, BIGNUM *e, BIGNUM *n, char **comment) |
| 188 | { |
| 189 | /* Return failure if no more entries. */ |
| 190 | if (auth->howmany <= 0) |
| 191 | return 0; |
| 192 | |
| 193 | /* Get the next entry from the packet. These will abort with a fatal |
| 194 | error if the packet is too short or contains corrupt data. */ |
| 195 | *bitsp = buffer_get_int(&auth->identities); |
| 196 | buffer_get_bignum(&auth->identities, e); |
| 197 | buffer_get_bignum(&auth->identities, n); |
| 198 | *comment = buffer_get_string(&auth->identities, NULL); |
| 199 | |
| 200 | /* Decrement the number of remaining entries. */ |
| 201 | auth->howmany--; |
| 202 | |
| 203 | return 1; |
| 204 | } |
| 205 | |
| 206 | /* Generates a random challenge, sends it to the agent, and waits for response |
| 207 | from the agent. Returns true (non-zero) if the agent gave the correct |
| 208 | answer, zero otherwise. Response type selects the style of response |
| 209 | desired, with 0 corresponding to protocol version 1.0 (no longer supported) |
| 210 | and 1 corresponding to protocol version 1.1. */ |
| 211 | |
| 212 | int |
| 213 | ssh_decrypt_challenge(AuthenticationConnection *auth, |
| 214 | int bits, BIGNUM *e, BIGNUM *n, BIGNUM *challenge, |
| 215 | unsigned char session_id[16], |
| 216 | unsigned int response_type, |
| 217 | unsigned char response[16]) |
| 218 | { |
| 219 | Buffer buffer; |
| 220 | unsigned char buf[8192]; |
| 221 | int len, l, i; |
| 222 | |
| 223 | /* Response type 0 is no longer supported. */ |
| 224 | if (response_type == 0) |
| 225 | fatal("Compatibility with ssh protocol version 1.0 no longer supported."); |
| 226 | |
| 227 | /* Format a message to the agent. */ |
| 228 | buf[0] = SSH_AGENTC_RSA_CHALLENGE; |
| 229 | buffer_init(&buffer); |
| 230 | buffer_append(&buffer, (char *)buf, 1); |
| 231 | buffer_put_int(&buffer, bits); |
| 232 | buffer_put_bignum(&buffer, e); |
| 233 | buffer_put_bignum(&buffer, n); |
| 234 | buffer_put_bignum(&buffer, challenge); |
| 235 | buffer_append(&buffer, (char *)session_id, 16); |
| 236 | buffer_put_int(&buffer, response_type); |
| 237 | |
| 238 | /* Get the length of the message, and format it in the buffer. */ |
| 239 | len = buffer_len(&buffer); |
| 240 | PUT_32BIT(buf, len); |
| 241 | |
| 242 | /* Send the length and then the packet to the agent. */ |
| 243 | if (write(auth->fd, buf, 4) != 4 || |
| 244 | write(auth->fd, buffer_ptr(&buffer), buffer_len(&buffer)) != |
| 245 | buffer_len(&buffer)) |
| 246 | { |
| 247 | error("Error writing to authentication socket."); |
| 248 | error_cleanup: |
| 249 | buffer_free(&buffer); |
| 250 | return 0; |
| 251 | } |
| 252 | |
| 253 | /* Wait for response from the agent. First read the length of the |
| 254 | response packet. */ |
| 255 | len = 4; |
| 256 | while (len > 0) |
| 257 | { |
| 258 | l = read(auth->fd, buf + 4 - len, len); |
| 259 | if (l <= 0) |
| 260 | { |
| 261 | error("Error reading response length from authentication socket."); |
| 262 | goto error_cleanup; |
| 263 | } |
| 264 | len -= l; |
| 265 | } |
| 266 | |
| 267 | /* Extract the length, and check it for sanity. */ |
| 268 | len = GET_32BIT(buf); |
| 269 | if (len > 256*1024) |
| 270 | fatal("Authentication response too long: %d", len); |
| 271 | |
| 272 | /* Read the rest of the response in tothe buffer. */ |
| 273 | buffer_clear(&buffer); |
| 274 | while (len > 0) |
| 275 | { |
| 276 | l = len; |
| 277 | if (l > sizeof(buf)) |
| 278 | l = sizeof(buf); |
| 279 | l = read(auth->fd, buf, l); |
| 280 | if (l <= 0) |
| 281 | { |
| 282 | error("Error reading response from authentication socket."); |
| 283 | goto error_cleanup; |
| 284 | } |
| 285 | buffer_append(&buffer, (char *)buf, l); |
| 286 | len -= l; |
| 287 | } |
| 288 | |
| 289 | /* Get the type of the packet. */ |
| 290 | buffer_get(&buffer, (char *)buf, 1); |
| 291 | |
| 292 | /* Check for agent failure message. */ |
| 293 | if (buf[0] == SSH_AGENT_FAILURE) |
| 294 | { |
| 295 | log("Agent admitted failure to authenticate using the key."); |
| 296 | goto error_cleanup; |
| 297 | } |
| 298 | |
| 299 | /* Now it must be an authentication response packet. */ |
| 300 | if (buf[0] != SSH_AGENT_RSA_RESPONSE) |
| 301 | fatal("Bad authentication response: %d", buf[0]); |
| 302 | |
| 303 | /* Get the response from the packet. This will abort with a fatal error |
| 304 | if the packet is corrupt. */ |
| 305 | for (i = 0; i < 16; i++) |
| 306 | response[i] = buffer_get_char(&buffer); |
| 307 | |
| 308 | /* The buffer containing the packet is no longer needed. */ |
| 309 | buffer_free(&buffer); |
| 310 | |
| 311 | /* Correct answer. */ |
| 312 | return 1; |
| 313 | } |
| 314 | |
| 315 | /* Adds an identity to the authentication server. This call is not meant to |
| 316 | be used by normal applications. */ |
| 317 | |
| 318 | int ssh_add_identity(AuthenticationConnection *auth, |
| 319 | RSA *key, const char *comment) |
| 320 | { |
| 321 | Buffer buffer; |
| 322 | unsigned char buf[8192]; |
| 323 | int len, l, type; |
| 324 | |
| 325 | /* Format a message to the agent. */ |
| 326 | buffer_init(&buffer); |
| 327 | buffer_put_char(&buffer, SSH_AGENTC_ADD_RSA_IDENTITY); |
| 328 | buffer_put_int(&buffer, BN_num_bits(key->n)); |
| 329 | buffer_put_bignum(&buffer, key->n); |
| 330 | buffer_put_bignum(&buffer, key->e); |
| 331 | buffer_put_bignum(&buffer, key->d); |
| 332 | /* To keep within the protocol: p < q for ssh. in SSL p > q */ |
| 333 | buffer_put_bignum(&buffer, key->iqmp); /* ssh key->u */ |
| 334 | buffer_put_bignum(&buffer, key->q); /* ssh key->p, SSL key->q */ |
| 335 | buffer_put_bignum(&buffer, key->p); /* ssh key->q, SSL key->p */ |
| 336 | buffer_put_string(&buffer, comment, strlen(comment)); |
| 337 | |
| 338 | /* Get the length of the message, and format it in the buffer. */ |
| 339 | len = buffer_len(&buffer); |
| 340 | PUT_32BIT(buf, len); |
| 341 | |
| 342 | /* Send the length and then the packet to the agent. */ |
| 343 | if (write(auth->fd, buf, 4) != 4 || |
| 344 | write(auth->fd, buffer_ptr(&buffer), buffer_len(&buffer)) != |
| 345 | buffer_len(&buffer)) |
| 346 | { |
| 347 | error("Error writing to authentication socket."); |
| 348 | error_cleanup: |
| 349 | buffer_free(&buffer); |
| 350 | return 0; |
| 351 | } |
| 352 | |
| 353 | /* Wait for response from the agent. First read the length of the |
| 354 | response packet. */ |
| 355 | len = 4; |
| 356 | while (len > 0) |
| 357 | { |
| 358 | l = read(auth->fd, buf + 4 - len, len); |
| 359 | if (l <= 0) |
| 360 | { |
| 361 | error("Error reading response length from authentication socket."); |
| 362 | goto error_cleanup; |
| 363 | } |
| 364 | len -= l; |
| 365 | } |
| 366 | |
| 367 | /* Extract the length, and check it for sanity. */ |
| 368 | len = GET_32BIT(buf); |
| 369 | if (len > 256*1024) |
| 370 | fatal("Add identity response too long: %d", len); |
| 371 | |
| 372 | /* Read the rest of the response in tothe buffer. */ |
| 373 | buffer_clear(&buffer); |
| 374 | while (len > 0) |
| 375 | { |
| 376 | l = len; |
| 377 | if (l > sizeof(buf)) |
| 378 | l = sizeof(buf); |
| 379 | l = read(auth->fd, buf, l); |
| 380 | if (l <= 0) |
| 381 | { |
| 382 | error("Error reading response from authentication socket."); |
| 383 | goto error_cleanup; |
| 384 | } |
| 385 | buffer_append(&buffer, (char *)buf, l); |
| 386 | len -= l; |
| 387 | } |
| 388 | |
| 389 | /* Get the type of the packet. */ |
| 390 | type = buffer_get_char(&buffer); |
| 391 | switch (type) |
| 392 | { |
| 393 | case SSH_AGENT_FAILURE: |
| 394 | buffer_free(&buffer); |
| 395 | return 0; |
| 396 | case SSH_AGENT_SUCCESS: |
| 397 | buffer_free(&buffer); |
| 398 | return 1; |
| 399 | default: |
| 400 | fatal("Bad response to add identity from authentication agent: %d", |
| 401 | type); |
| 402 | } |
| 403 | /*NOTREACHED*/ |
| 404 | return 0; |
| 405 | } |
| 406 | |
| 407 | /* Removes an identity from the authentication server. This call is not meant |
| 408 | to be used by normal applications. */ |
| 409 | |
| 410 | int ssh_remove_identity(AuthenticationConnection *auth, RSA *key) |
| 411 | { |
| 412 | Buffer buffer; |
| 413 | unsigned char buf[8192]; |
| 414 | int len, l, type; |
| 415 | |
| 416 | /* Format a message to the agent. */ |
| 417 | buffer_init(&buffer); |
| 418 | buffer_put_char(&buffer, SSH_AGENTC_REMOVE_RSA_IDENTITY); |
| 419 | buffer_put_int(&buffer, BN_num_bits(key->n)); |
| 420 | buffer_put_bignum(&buffer, key->e); |
| 421 | buffer_put_bignum(&buffer, key->n); |
| 422 | |
| 423 | /* Get the length of the message, and format it in the buffer. */ |
| 424 | len = buffer_len(&buffer); |
| 425 | PUT_32BIT(buf, len); |
| 426 | |
| 427 | /* Send the length and then the packet to the agent. */ |
| 428 | if (write(auth->fd, buf, 4) != 4 || |
| 429 | write(auth->fd, buffer_ptr(&buffer), buffer_len(&buffer)) != |
| 430 | buffer_len(&buffer)) |
| 431 | { |
| 432 | error("Error writing to authentication socket."); |
| 433 | error_cleanup: |
| 434 | buffer_free(&buffer); |
| 435 | return 0; |
| 436 | } |
| 437 | |
| 438 | /* Wait for response from the agent. First read the length of the |
| 439 | response packet. */ |
| 440 | len = 4; |
| 441 | while (len > 0) |
| 442 | { |
| 443 | l = read(auth->fd, buf + 4 - len, len); |
| 444 | if (l <= 0) |
| 445 | { |
| 446 | error("Error reading response length from authentication socket."); |
| 447 | goto error_cleanup; |
| 448 | } |
| 449 | len -= l; |
| 450 | } |
| 451 | |
| 452 | /* Extract the length, and check it for sanity. */ |
| 453 | len = GET_32BIT(buf); |
| 454 | if (len > 256*1024) |
| 455 | fatal("Remove identity response too long: %d", len); |
| 456 | |
| 457 | /* Read the rest of the response in tothe buffer. */ |
| 458 | buffer_clear(&buffer); |
| 459 | while (len > 0) |
| 460 | { |
| 461 | l = len; |
| 462 | if (l > sizeof(buf)) |
| 463 | l = sizeof(buf); |
| 464 | l = read(auth->fd, buf, l); |
| 465 | if (l <= 0) |
| 466 | { |
| 467 | error("Error reading response from authentication socket."); |
| 468 | goto error_cleanup; |
| 469 | } |
| 470 | buffer_append(&buffer, (char *)buf, l); |
| 471 | len -= l; |
| 472 | } |
| 473 | |
| 474 | /* Get the type of the packet. */ |
| 475 | type = buffer_get_char(&buffer); |
| 476 | switch (type) |
| 477 | { |
| 478 | case SSH_AGENT_FAILURE: |
| 479 | buffer_free(&buffer); |
| 480 | return 0; |
| 481 | case SSH_AGENT_SUCCESS: |
| 482 | buffer_free(&buffer); |
| 483 | return 1; |
| 484 | default: |
| 485 | fatal("Bad response to remove identity from authentication agent: %d", |
| 486 | type); |
| 487 | } |
| 488 | /*NOTREACHED*/ |
| 489 | return 0; |
| 490 | } |
| 491 | |
| 492 | /* Removes all identities from the agent. This call is not meant |
| 493 | to be used by normal applications. */ |
| 494 | |
| 495 | int ssh_remove_all_identities(AuthenticationConnection *auth) |
| 496 | { |
| 497 | Buffer buffer; |
| 498 | unsigned char buf[8192]; |
| 499 | int len, l, type; |
| 500 | |
| 501 | /* Get the length of the message, and format it in the buffer. */ |
| 502 | PUT_32BIT(buf, 1); |
| 503 | buf[4] = SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES; |
| 504 | |
| 505 | /* Send the length and then the packet to the agent. */ |
| 506 | if (write(auth->fd, buf, 5) != 5) |
| 507 | { |
| 508 | error("Error writing to authentication socket."); |
| 509 | return 0; |
| 510 | } |
| 511 | |
| 512 | /* Wait for response from the agent. First read the length of the |
| 513 | response packet. */ |
| 514 | len = 4; |
| 515 | while (len > 0) |
| 516 | { |
| 517 | l = read(auth->fd, buf + 4 - len, len); |
| 518 | if (l <= 0) |
| 519 | { |
| 520 | error("Error reading response length from authentication socket."); |
| 521 | return 0; |
| 522 | } |
| 523 | len -= l; |
| 524 | } |
| 525 | |
| 526 | /* Extract the length, and check it for sanity. */ |
| 527 | len = GET_32BIT(buf); |
| 528 | if (len > 256*1024) |
| 529 | fatal("Remove identity response too long: %d", len); |
| 530 | |
| 531 | /* Read the rest of the response into the buffer. */ |
| 532 | buffer_init(&buffer); |
| 533 | while (len > 0) |
| 534 | { |
| 535 | l = len; |
| 536 | if (l > sizeof(buf)) |
| 537 | l = sizeof(buf); |
| 538 | l = read(auth->fd, buf, l); |
| 539 | if (l <= 0) |
| 540 | { |
| 541 | error("Error reading response from authentication socket."); |
| 542 | buffer_free(&buffer); |
| 543 | return 0; |
| 544 | } |
| 545 | buffer_append(&buffer, (char *)buf, l); |
| 546 | len -= l; |
| 547 | } |
| 548 | |
| 549 | /* Get the type of the packet. */ |
| 550 | type = buffer_get_char(&buffer); |
| 551 | switch (type) |
| 552 | { |
| 553 | case SSH_AGENT_FAILURE: |
| 554 | buffer_free(&buffer); |
| 555 | return 0; |
| 556 | case SSH_AGENT_SUCCESS: |
| 557 | buffer_free(&buffer); |
| 558 | return 1; |
| 559 | default: |
| 560 | fatal("Bad response to remove identity from authentication agent: %d", |
| 561 | type); |
| 562 | } |
| 563 | /*NOTREACHED*/ |
| 564 | return 0; |
| 565 | } |